Polyamide composition and molded article made of the polyamide composition

Abstract

To provide: a polyamide composition that has high-level flame retardancy in a thin form as well as excellent heat resistance and moldability; and a molded article comprising the polyamide composition.SOLUTION: Provided are: a polyamide composition comprising a polyamide (A) having a melting point of 280°C or higher, a flame retardant (B), and an aromatic vinyl-based copolymer (C), where the aromatic vinyl-based copolymer (C) comprises a structural unit derived from an aromatic vinyl and a structural unit derived from an α,β-unsaturated dicarboxylic acid anhydride, the glass transition temperature of the aromatic vinyl-based copolymer (C) is 140°C or higher, and a content of the aromatic vinyl-based copolymer (C) is 0.3-2.0 mass% relative to the total content of the polyamide (A), the flame retardant (B), and the aromatic vinyl-based copolymer (C); and a molded article comprising the polyamide composition.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a polyamide composition and a molded article made of the polyamide composition.

Background Art

[0002] Since polyamides are excellent in mechanical properties, moldability, etc., they are used in various applications such as electric and electronic parts, automotive parts, mechanical parts, industrial parts, fibers, films, sheets, etc. Especially in the application of electric and electronic parts, since a high degree of flame retardancy based on the UL-94 standard is required, methods for flame-retardantizing polyamide compositions with various flame retardants have been proposed.

[0003] For example, in Patent Document 1, a polyamide composition containing a specific polyamide, a specific glass fiber, and a bromine-based flame retardant is proposed, and it is described that it is excellent in fluidity, etc. Also, in Patent Documents 2 to 3, a flame-retardant polyamide resin composition containing a polyamide in which the ratio of terminal amino groups or terminal carboxyl groups is in a specific range, brominated polystyrene, and a copolymer of an aromatic vinyl compound and an α,β-unsaturated dicarboxylic anhydride is proposed, and it is described that it is excellent in flame retardancy in thin walls, extrusion processability, molding processability, etc. Further, in Patent Document 4, in a polyamide composition containing a polyamide having a melting point in a specific range, a flame retardant, and a dripping inhibitor, as the dripping inhibitor, a fluororesin and at least one polymer selected from the group consisting of an ionomer and a modified aromatic vinyl-based polymer are used in a specific range of mass ratio, and a polyamide composition is proposed, and it is described that it is excellent in flame retardancy, heat resistance, moldability (fluidity), etc., which is suitable as a material for molding electronic parts having a thin wall portion.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] Here, regarding electrical and electronic components, in their mounting, with the miniaturization and weight reduction of the product size, along with the miniaturization and thinning of the components, a higher degree of flame retardancy in the thin film is required. Also, in electrical and electronic components that require reflow solder heat resistance with the progress of recent surface mounting technology (SMT), and in automotive components where the requirement for heat resistance is increasing, further improvement in the heat resistance and moldability of polyamide compositions is required. However, the technologies of Patent Documents 1 to 3 are not sufficiently satisfactory in terms of high flame retardancy, heat resistance, and moldability in thin films. Also, although the technology of Patent Document 4 improves flame retardancy, heat resistance, moldability, etc., further improvement in performance is desired.

[0006] In view of the above circumstances, an object of the present invention is to provide a polyamide composition having a high degree of flame retardancy in a thin film and excellent heat resistance and moldability, and a molded article made of the polyamide composition. [Means for Solving the Problems]

[0007] The present inventors have found that a polyamide composition containing a specific polyamide, a flame retardant, and an aromatic vinyl copolymer, wherein the aromatic vinyl copolymer contains a specific structural unit, the glass transition temperature of the aromatic vinyl copolymer is in a specific range, and the aromatic vinyl copolymer is contained in a specific ratio can solve the above problems, and based on this finding, further studies have been repeated to complete the present invention. That is, the present invention relates to the following [1] to

[13] . [1] A polyamide composition containing a polyamide (A) having a melting point of 280 °C or higher, a flame retardant (B), and an aromatic vinyl copolymer (C). The aromatic vinyl copolymer (C) includes a structural unit derived from an aromatic vinyl and a structural unit derived from an α,β-unsaturated dicarboxylic anhydride, and the glass transition temperature of the aromatic vinyl copolymer (C) is 140 °C or higher. The content of the aromatic vinyl copolymer (C) is 0.3 to 2.0% by mass based on the total content of the polyamide (A), the flame retardant (B), and the aromatic vinyl copolymer (C). [2] The polyamide composition according to [1], wherein the polyamide (A) is a semi-aromatic polyamide. [3] In the semi-aromatic polyamide, more than 50 mol% of the structural units derived from the dicarboxylic acid constituting the semi-aromatic polyamide are structural units derived from an aromatic dicarboxylic acid, and more than 50 mol% of the structural units derived from the diamine constituting the semi-aromatic polyamide are structural units derived from an aliphatic diamine having 4 to 18 carbon atoms. [4] The polyamide composition according to [3], wherein the aliphatic diamine is at least one selected from the group consisting of 1,6-hexanediamine, 1,9-nonanediamine, 2-methyl-1,8-octanediamine, and 1,10-decanediamine. [5] The polyamide composition according to any one of [1] to [4], wherein the flame retardant (B) is a brominated flame retardant. [6] The polyamide composition according to any one of [1] to [5], wherein the structural unit derived from the aromatic vinyl includes a structural unit derived from at least one selected from the group consisting of styrene and α-methylstyrene. [7] The polyamide composition according to any one of [1] to [6], wherein the α,β-unsaturated dicarboxylic anhydride is at least one selected from the group consisting of maleic anhydride and monoalkyl maleic anhydride having an alkyl group with 1 to 3 carbon atoms. [8] The polyamide composition according to any one of [1] to [7], wherein the content of the structural unit derived from the α,β-unsaturated dicarboxylic anhydride in the aromatic vinyl copolymer (C) is 18 to 50% by mass. [9] The polyamide composition according to any one of [1] to [8], wherein the weight average molecular weight (Mw) of the aromatic vinyl copolymer (C) is 10,000 to 500,000.

[10] The polyamide composition according to any one of [1] to [9], further containing a filler (D).

[11] The polyamide composition according to any one of [1] to [9], wherein the polyamide composition is obtained by melt-kneading a polyamide (A), a flame retardant (B), and an aromatic vinyl copolymer (C).

[12] The polyamide composition according to

[10] , wherein the polyamide composition is obtained by melt-kneading a polyamide (A), a flame retardant (B), an aromatic vinyl copolymer (C), and a filler (D).

[13] A molded article made of the polyamide composition according to any one of [1] to

[12] .

Effect of the Invention

[0008] According to the present invention, it is possible to provide a polyamide composition having high flame retardancy in a thin wall and excellent heat resistance and moldability, and a molded article made of the polyamide composition.

Mode for Carrying Out the Invention

[0009] [Polyamide Composition] The polyamide composition of the present invention contains a polyamide (A) having a melting point of 280°C or higher (hereinafter, also simply referred to as "polyamide (A)"), a flame retardant (B), and an aromatic vinyl copolymer (C) (hereinafter, also referred to as "copolymer (C)"). The copolymer (C) includes a structural unit derived from an aromatic vinyl and a structural unit derived from an α,β-unsaturated dicarboxylic anhydride. The glass transition temperature of the copolymer (C) is 140°C or higher, and the content of the copolymer (C) is 0.3 to 2.0% by mass based on the total content of the polyamide (A), the flame retardant (B), and the copolymer (C).

[0010] The polyamide composition of the present invention contains a polyamide (A) having a specific melting point, a flame retardant (B), and a specific aromatic vinyl copolymer (C), and by containing the aromatic vinyl copolymer in a specific ratio, the polyamide composition has high flame retardancy even in a thin wall, and also has excellent heat resistance and moldability. The reason for this is unclear, but is presumed to be as follows. The polyamide (A) according to the present invention has a melting point of 280°C or higher, and the copolymer (C) has a glass transition temperature of 140°C or higher, resulting in improved heat resistance. Furthermore, the α,β-unsaturated dicarboxylic anhydride units in the copolymer (C) react with the carboxyl or amino terminals of the polyamide (A), thereby increasing the viscosity of the polyamide composition, improving melt tension, and suppressing dripping. Furthermore, the reaction reduces the amount of carboxyl terminals, thereby suppressing decomposition of the polyamide (A) at high temperatures. As a result, it is believed that the flame retardancy of thin-walled structures can be improved. Furthermore, by setting the content of the copolymer (C) in the polyamide composition at a specific ratio, it is believed that the viscosity of the polyamide composition does not become too high, thereby achieving both high flame retardancy and excellent moldability in thin-walled structures.

[0011] <Polyamide (A)> The polyamide composition of the present invention contains a polyamide (A) having a melting point of 280°C or higher. Examples of the polyamide (A) include condensation polymers of dicarboxylic acids and diamines, ring-opening polymers of cyclic lactams, and condensation polymers of aminocarboxylic acids. In this specification, the term "unit" (where "" indicates a monomer) means "a structural unit derived from", for example, a "dicarboxylic acid unit" means "a structural unit derived from a dicarboxylic acid", and a "diamine unit" means "a structural unit derived from a diamine".

[0012] Examples of the dicarboxylic acid include aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, dimethylmalonic acid, 2,2 - diethylsuccinic acid, 2,2 - dimethylglutaric acid, 2 - methyladipic acid, and trimethyladipic acid; alicyclic dicarboxylic acids such as 1,3 - cyclopentanedicarboxylic acid, 1,3 - cyclohexanedicarboxylic acid, 1,4 - cyclohexanedicarboxylic acid, cycloheptanedicarboxylic acid, cyclooctanedicarboxylic acid, and cyclodecanedicarboxylic acid; and aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, 2,6 - naphthalenedicarboxylic acid, 2,7 - naphthalenedicarboxylic acid, 1,4 - naphthalenedicarboxylic acid, 1,4 - phenylenedioxydiacetic acid, 1,3 - phenylenedioxydiacetic acid, diphenic acid, diphenylmethane - 4,4'-dicarboxylic acid, diphenylsulfone - 4,4'-dicarboxylic acid, and 4,4'-biphenyldicarboxylic acid. These dicarboxylic acids can be used alone or in combination of two or more. Within the range that does not impair the effects of the present invention, the polyamide (A) may further contain structural units derived from polyvalent carboxylic acids having three or more valences, such as trimellitic acid, trimesic acid, and pyromellitic acid, within the range where melt molding is possible.

[0013] Examples of the diamine include aliphatic diamines, alicyclic diamines, aromatic diamines, etc. Examples of the aliphatic diamine include linear aliphatic diamines such as ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine; branched-chain aliphatic diamines such as 1-butyl-1,2-ethanediamine, 1,1-dimethyl-1,4-butanediamine, 1-ethyl-1,4-butanediamine, 1,2-dimethyl-1,4-butanediamine, 1,3-dimethyl-1,4-butanediamine, 1,4-dimethyl-1,4-butanediamine, 2,3-dimethyl-1,4-butanediamine, 2-methyl-1,5-pentanediamine, 3-methyl-1,5-pentanediamine, 2,5-dimethyl-1,6-hexanediamine, 2,4-dimethyl-1,6-hexanediamine, 3,3-dimethyl-1,6-hexanediamine, 2,2-dimethyl-1,6-hexanediamine, 2,2,4-trimethyl-1,6-hexanediamine, 2,4,4-trimethyl-1,6-hexanediamine, 2,4-diethyl-1,6-hexanediamine, 2,2-dimethyl-1,7-heptanediamine, 2,3-dimethyl-1,7-heptanediamine, 2,4-dimethyl-1,7-heptanediamine, 2,5-dimethyl-1,7-heptanediamine, 2-methyl-1,8-octanediamine, 3-methyl-1,8-octanediamine, 4-methyl-1,8-octanediamine, 1,3-dimethyl-1,8-octanediamine, 1,4-dimethyl-1,8-octanediamine, 2,4-dimethyl-1,8-octanediamine, 3,4-dimethyl-1,8-octanediamine, 4,5-dimethyl-1,8-octanediamine, 2,2-dimethyl-1,8-octanediamine, 3,3-dimethyl-1,8-octanediamine, 4,4-dimethyl-1,8-octanediamine, 5-methyl-1,9-nonanediamine, etc.

[0014] Examples of the alicyclic diamine include cyclohexanediamine, methylcyclohexanediamine, isophoronediamine, norbornanedimethylamine, tricyclodecanedimethylamine, and the like. Examples of the aromatic diamine include p-phenylenediamine, m-phenylenediamine, p-xylylenediamine, m-xylylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylether, and the like. These diamines can be used alone or in combination of two or more. The polyamide (A) may further contain, within a range not impairing the effects of the present invention, structural units derived from a polyamine having a trivalent or higher valence such as bis(hexamethylene)triamine, as long as melt molding is possible.

[0015] Examples of the cyclic lactam include acetolactam, propiolactam, butyrolactam, valerolactam, caprolactam, enantholactam, caprylolactam, pelargolactam, caprinolactam, laurolactam, and the like. Examples of the aminocarboxylic acid include aminopropionic acid, aminobutyric acid, aminovaleric acid, aminocaproic acid, aminoenanthic acid, aminocaprylic acid, aminopelargonic acid, aminocapric acid, aminolauric acid, and the like.

[0016] The polyamide (A) is preferably used as an aliphatic polyamide, wholly aromatic polyamide or semi-aromatic polyamide by appropriately combining monomers such as the above dicarboxylic acid, diamine, cyclic lactam, aminocarboxylic acid, polycarboxylic acid having a trivalent or higher valence, and polyamine having a trivalent or higher valence so that the melting point becomes 280°C or higher. In the present invention, the "wholly aromatic polyamide" means a polyamide in which more than 50 mol% of the dicarboxylic acid units constituting the polyamide are aromatic dicarboxylic acid units and more than 50 mol% of the diamine units constituting the polyamide are aromatic diamine units. In the present invention, the "semi-aromatic polyamide" refers to a polyamide in which more than 50 mol% of the dicarboxylic acid units constituting the polyamide are aromatic dicarboxylic acid units and more than 50 mol% of the diamine units constituting the polyamide are aliphatic diamine units, or a polyamide in which more than 50 mol% of the dicarboxylic acid units constituting the polyamide are aliphatic dicarboxylic acid units and more than 50 mol% of the diamine units constituting the polyamide are aromatic diamine units. Among these, from the viewpoints of flame retardancy, heat resistance, and moldability in thin walls, at least one selected from the group consisting of aliphatic polyamides and semi-aromatic polyamides is preferable, and semi-aromatic polyamides are more preferable.

[0017] Examples of the aliphatic polyamide include ring-opening polymers of the cyclic lactam, polycondensates of the aminocarboxylic acid, or polycondensates of the aliphatic dicarboxylic acid and the aliphatic diamine. Among them, from the viewpoints of flame retardancy, heat resistance, and moldability in thin walls, the polycondensate of the aliphatic dicarboxylic acid and the aliphatic diamine is preferable, and polyamide 46 is more preferable from the viewpoint of ease of production.

[0018] As the semi-aromatic polyamide, from the viewpoints of flame retardancy, heat resistance, and moldability in thin walls, those in which more than 50 mol% of the dicarboxylic acid units constituting the semi-aromatic polyamide are aromatic dicarboxylic acid units and more than 50 mol% of the diamine units constituting the semi-aromatic polyamide are aliphatic diamine units are preferable.

[0019] Examples of the aromatic dicarboxylic acid constituting the semi-aromatic polyamide include the aforementioned aromatic dicarboxylic acids. Among them, phthalic acid, isophthalic acid, and terephthalic acid are preferable, isophthalic acid and terephthalic acid are more preferable, and terephthalic acid is even more preferable. The content of the aromatic dicarboxylic acid units in all the dicarboxylic acid units constituting the semi-aromatic polyamide is preferably 60 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, still more preferably 90 mol% or more, and 100 mol% or less from the viewpoint of heat resistance. The semi-aromatic polyamide may contain dicarboxylic acid units other than aromatic dicarboxylic acid units. Examples of such other dicarboxylic acids include the aforementioned aliphatic dicarboxylic acids and alicyclic dicarboxylic acids. The content of other dicarboxylic acid units in all the dicarboxylic acid units constituting the semi-aromatic polyamide is preferably 40 mol% or less, more preferably 30 mol% or less, still more preferably 20 mol% or less, and even more preferably 10 mol% or less.

[0020] Examples of the aliphatic diamine constituting the semi-aromatic polyamide include the aforementioned aliphatic diamines. From the viewpoint of excellent physical properties such as heat resistance and low water absorption, the number of carbon atoms of the aliphatic diamine is preferably 4 or more, more preferably 6 or more, still more preferably 8 or more, and preferably 18 or less, more preferably 12 or less. From the viewpoint of excellent physical properties such as heat resistance and low water absorption, the aliphatic diamine is preferably at least one selected from the group consisting of 1,6-hexanediamine, 1,9-nonanediamine, 2-methyl-1,8-octanediamine, and 1,10-decanediamine, more preferably at least one selected from the group consisting of 1,9-nonanediamine and 2-methyl-1,8-octanediamine, and even more preferably a combination of 1,9-nonanediamine and 2-methyl-1,8-octanediamine. The content of the aliphatic diamine units in all the diamine units constituting the semi-aromatic polyamide is preferably 60 mol% or more, more preferably 70 mol% or more, still more preferably 80 mol% or more, and even more preferably 90 mol% or more, and 100 mol% or less. The semi-aromatic polyamide may contain diamine units other than aliphatic diamine units. Examples of such other diamines include the aforementioned aromatic diamines and alicyclic diamines. The content of other diamine units in all the diamine units constituting the semi-aromatic polyamide is preferably 40 mol% or less, more preferably 30 mol% or less, still more preferably 20 mol% or less, and even more preferably 10 mol% or less.

[0021] When 1,9-nonanediamine and 2-methyl-1,8-octanediamine are used in combination as the aliphatic diamine, from the viewpoint of heat resistance, the molar ratio of 1,9-nonanediamine to 2-methyl-1,8-octanediamine (1,9-nonanediamine / 2-methyl-1,8-octanediamine) is preferably in the range of 95 / 5 to 40 / 60, more preferably in the range of 90 / 10 to 50 / 50, and even more preferably in the range of 90 / 10 to 60 / 40.

[0022] Further, the semi-aromatic polyamide may contain structural units derived from cyclic lactams and / or aminocarboxylic acids. Examples of these structural units include structural units derived from cyclic lactams such as caprolactam and laurolactam; and aminocarboxylic acids such as 11-aminoundecanoic acid and 12-aminododecanoic acid. The total content of the cyclic lactam units and aminocarboxylic acid units in the semi-aromatic polyamide is preferably 40 mol% or less, more preferably 20 mol% or less, based on 100 mol% of the total of the dicarboxylic acid units and diamine units constituting the semi-aromatic polyamide.

[0023] Specific examples of the semi-aromatic polyamide include polytetramethylene terephthalamide (polyamide 4T), polyhexamethylene terephthalamide (polyamide 6T), polynonamethylene terephthalamide (polyamide 9T), polydecamethylene terephthalamide (polyamide 10T), polyhexamethylene isophthalamide (polyamide 6I), a copolymer of polyamide 6I and polyamide 6T (polyamide 6I / 6T), and a copolymer of polyamide 6T and polyundecanamide (polyamide 11) (polyamide 6T / 11). Among them, at least one selected from the group consisting of polyamide 4T, polyamide 6T, polyamide 9T, and polyamide 10T is preferred, at least one selected from the group consisting of polyamide 9T and polyamide 10T is more preferred, and polyamide 9T is even more preferred.

[0024] The polyamide (A) used in the present invention preferably has at least 10% of the terminal groups of its molecular chain blocked by a terminal blocking agent. The ratio of the terminal groups of the molecular chain blocked by the terminal blocking agent (terminal blocking rate) is more preferably 20% or more. As the terminal blocking agent, a monofunctional compound having reactivity with the amino group or carboxyl group at the end of the polyamide can be used. From the viewpoints of reactivity and stability of the blocked terminal, monocarboxylic acid or monoamine is preferred, and monocarboxylic acid is more preferred from the viewpoint of ease of handling. In addition, monoisocyanate, monoacid halide, monoesters, monoalcohols, etc. can also be used as the terminal blocking agent.

[0025] As the monocarboxylic acid used as the terminal blocking agent, those having reactivity with the amino group can be used. For example, aliphatic monocarboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, pivalic acid, isobutyric acid; alicyclic monocarboxylic acids such as cyclohexanecarboxylic acid; aromatic monocarboxylic acids such as benzoic acid, toluic acid, α-naphthalenecarboxylic acid, β-naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid, phenylacetic acid; any mixtures thereof, etc. can be mentioned. Among them, from the viewpoints of reactivity, stability of the blocked terminal, price, etc., acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, benzoic acid are preferred.

[0026] As the monoamine used as the terminal blocking agent, those having reactivity with a carboxyl group can be used. For example, aliphatic monoamines such as methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, decylamine, stearylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine; cycloaliphatic monoamines such as cyclohexylamine, dicyclohexylamine; aromatic monoamines such as aniline, toluidine, diphenylamine, naphthylamine; and any mixtures thereof can be mentioned. Among them, from the viewpoints of reactivity, boiling point, stability of the blocked end, price, etc., butylamine, hexylamine, octylamine, decylamine, stearylamine, cyclohexylamine, aniline are preferable.

[0027] The terminal blocking rate of the polyamide (A) is determined according to the following formula (1) by measuring the number of carboxyl group terminals, amino group terminals, and terminal groups blocked by the terminal blocking agent present in the polyamide (A). The number of each terminal group is preferably determined from the integral value of the characteristic signal corresponding to each terminal group by H-NMR from the viewpoints of accuracy and simplicity. 1 It is preferable to determine it from the integral value of the characteristic signal corresponding to each terminal group by H-NMR. Terminal blocking rate (%) = [(T - S) / T] × 100 (1) [In the formula, T represents the total number of terminal groups in the molecular chain of the polyamide (A) (this is usually equal to twice the number of polyamide molecules), and S represents the total number of unblocked carboxyl group terminals and amino group terminals.]

[0028] The polyamide (A) used in the present invention can be produced by using any method known as a method for producing a crystalline polyamide. For example, it can be produced by a solution polymerization method or an interfacial polymerization method using a dicarboxylic acid and a diamine in the form of acid chloride as raw materials, a melt polymerization method using a dicarboxylic acid and a diamine as raw materials, a solid phase polymerization method, a melt extrusion polymerization method, and the like.

[0029] Polyamide (A) can be produced, for example, by first adding diamine, dicarboxylic acid, and optionally a catalyst and a terminal capping agent all at once to produce a nylon salt, and then subjecting it to heat polymerization at a temperature of 200 to 250 °C to obtain a prepolymer, followed by solid-phase polymerization or polymerization using a melt extruder. When the final stage of polymerization is carried out by solid-phase polymerization, it is preferably carried out under reduced pressure or under an inert gas flow. If the polymerization temperature is within the range of 200 to 280 °C, the polymerization rate is high, the productivity is excellent, and coloring and gelation can be effectively suppressed. When the final stage of polymerization is carried out by a melt extruder, the polymerization temperature is preferably 370 °C or lower. Polymerization under such conditions gives polyamide (A) with little decomposition and little deterioration.

[0030] Examples of the catalyst that can be used in the production of polyamide (A) include phosphoric acid, phosphorous acid, hypophosphorous acid, their salts or esters. Examples of the above salts or esters include salts of phosphoric acid, phosphorous acid or hypophosphorous acid with metals such as potassium, sodium, magnesium, vanadium, calcium, zinc, cobalt, manganese, tin, tungsten, germanium, titanium, antimony, etc.; ammonium salts of phosphoric acid, phosphorous acid or hypophosphorous acid; ethyl esters, isopropyl esters, butyl esters, hexyl esters, isodecyl esters, octadecyl esters, decyl esters, stearyl esters, phenyl esters of phosphoric acid, phosphorous acid or hypophosphorous acid, etc. Among them, sodium hypophosphite monohydrate or phosphorous acid is preferred.

[0031] The inherent viscosity [η] of polyamide (A) measured under the condition of 30 °C using concentrated sulfuric acid as a solvent is preferably 0.60 to 1.2 dl / g, more preferably 0.65 to 1.1 dl / g. If polyamide (A) with an inherent viscosity [η] of 0.60 dl / g or more is used, the mechanical properties of the resulting molded article will be good. Also, if polyamide (A) with an inherent viscosity [η] of 1.2 dl / g or less is used, the moldability will be further improved. The inherent viscosity [η] of polyamide (A) is measured by the method described in the examples.

[0032] From the perspective of heat resistance and other aspects such that the effects of the present invention are more remarkable, the melting point of polyamide (A) is 280 °C or higher, preferably 290 °C or higher, more preferably 300 °C or higher, and from the perspective of suppressing thermal decomposition of polyamide during melt molding, etc., it is preferably 350 °C or lower, more preferably 340 °C or lower, still more preferably 330 °C or lower. The melting point of polyamide (A) is measured by the method described in the examples.

[0033] <Flame retardant (B)> The polyamide composition of the present invention contains a flame retardant (B). Examples of the flame retardant (B) include phosphorus-based flame retardants; halogen-based flame retardants such as bromine-based flame retardants and chlorine-based flame retardants. Examples of the phosphorus-based flame retardants include red phosphorus; aliphatic phosphate esters such as trimethyl phosphate and triethyl phosphate; aromatic phosphate esters such as triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, cresyl di-2,6-xylenyl phosphate, tris(t-butylated phenyl) phosphate, tris(i-propylated phenyl) phosphate, and 2-ethylhexyl diphenyl phosphate; halogen-containing phosphate esters such as tris(dichloropropyl) phosphate, tris(β-chloropropyl) phosphate, tris(chloroethyl) phosphate, and tris(tribromoneopentyl) phosphate; aromatic condensed phosphate esters such as 1,3-phenylene bis(diphenyl phosphate), 1,3-phenylene bis(dixylenyl) phosphate, and bisphenol A bis(diphenyl phosphate); halogen-containing condensed phosphate esters such as 2,2-bis(chloromethyl)trimethylene bis(bis(2-chloroethyl) phosphate) and polyoxyalkylene bisdichloroalkyl phosphate; phosphoric acid amides; phosphates such as ammonium polyphosphate and melamine polyphosphate; phosphazene compounds, etc.

[0034] Examples of chlorine-based flame retardants include chlorinated paraffin, chlorinated polyethylene, dodecachloropentacyclooctadeca-7,15-diene (manufactured by Oxidental Chemical Co., Ltd., trade name "Dechlorane Plus 25"), maleic anhydride, and the like. Examples of bromine-based flame retardants include brominated polystyrene (which may be polybrominated styrene); brominated polyphenylene oxide; brominated bisphenol type epoxy polymer; brominated styrene-maleic anhydride polymer; brominated epoxy resin; brominated phenoxy resin; brominated polybenzyl (meth)acrylate such as polypentabromobenzyl acrylate; bromine-containing polycyclic compounds such as bis(pentabromophenyl)ethane, 1,2-bis(2,4,6-tribromophenoxy)ethane, 2,4,6-tris(2,4,6-tribromophenoxy)-1,3,5-triazine, 2,6-dibromophenol, 2,4-dibromophenol, and polybromophenyl indane; tetrabromobisphenol A and its derivatives such as tetrabromobisphenol A-bis(dibromopropyl ether), tetrabromobisphenol A-bis(aryl ether), tetrabromobisphenol A polycarbonate, and tetrabromobisphenol A epoxy oligomer; tetrabromobisphenol S and its derivatives such as tetrabromobisphenol S-bis(dibromopropyl ether); polybrominated diphenyl ethers such as decabromodiphenyl ether and octabromodiphenyl ether; polybrominated biphenyls such as decabromobiphenyl; brominated polycarbonate; bromine-containing cyclic aliphatic compounds such as hexabromocyclododecane; brominated crosslinked aromatic polymers; bromine-containing phthalic acid compounds such as tetrabromophthalic anhydride and N,N-ethylenebis(tetrabromophthal)imide; bromine-containing isocyanuric acid compounds such as tris(pentabromobenzyl)isocyanurate and tris(dibromopropyl)isocyanurate. These flame retardants can be used alone or in combination of two or more. The bromine atom content in the bromine-based flame retardant is preferably 15 to 87% by mass.

[0035] The flame retardant (B) is preferably at least one selected from the group consisting of a phosphorus-based flame retardant and a bromine-based flame retardant, more preferably a bromine-based flame retardant, from the viewpoints of flame retardancy, heat resistance, and moldability in thin sections. As the bromine-based flame retardant, at least one selected from the group consisting of brominated polystyrene, brominated polyphenylene oxide, brominated epoxy resin, brominated polybenzyl (meth)acrylate, bromine-containing polycyclic compound, tetrabromobisphenol A and its derivatives, tetrabromobisphenol S and its derivatives, polybrominated diphenyl ether, bromine-containing cycloaliphatic compound, bromine-containing phthalic acid compound, and bromine-containing isocyanuric acid compound is preferable, and at least one selected from the group consisting of brominated polystyrene, brominated polyphenylene oxide, brominated epoxy resin, polypentabromobenzyl acrylate, bis(pentabromophenyl)ethane, 2,4,6-tris(2,4,6-tribromophenoxy)-1,3,5-triazine, polybromophenyl indane, tetrabromobisphenol A-bis(dibromopropyl ether), tetrabromobisphenol A polycarbonate, tetrabromobisphenol S-bis(dibromopropyl ether), decabromodiphenyl ether, hexabromocyclododecane, N,N-ethylenebis(tetrabromophthal)imide, and tris(dibromopropyl)isocyanurate is more preferable. Among them, from the viewpoint of being able to withstand molding at high temperatures, at least one selected from the group consisting of brominated polystyrene, brominated epoxy resin, and N,N-ethylenebis(tetrabromophthal)imide is even more preferable, and brominated polystyrene is even more preferably. There is no particular limitation on the method for producing brominated polystyrene. For example, it can be produced by a method of polymerizing styrene to produce polystyrene and then brominating the benzene ring of polystyrene, or a method of polymerizing brominated styrene (bromostyrene, dibromostyrene, tribromostyrene, etc.). The bromine atom content in the brominated polystyrene is preferably 55 to 75% by mass. When the bromine atom content is 55% by mass or more, the content of the brominated polystyrene for satisfying the amount of bromine required for flame retardancy can be reduced, and high-level flame retardancy in thin walls can be imparted without deteriorating mechanical properties and heat resistance. Further, when the bromine atom content is 75% by mass or less, the decrease in the thermal stability of the brominated polystyrene and the thermal decomposition during melt molding can be reduced, gas generation can be suppressed, and discoloration due to heat can be suppressed.

[0036] <Flame retardant aid> From the viewpoint of imparting excellent flame retardancy in thin walls with a small amount of flame retardant, the polyamide composition of the present invention preferably contains a flame retardant aid in addition to the bromine-based flame retardant. Examples of the flame retardant aid include antimony trioxide, antimony pentoxide, sodium antimonate, sodium oxide, tin oxide, zinc stannate, zinc oxide, iron oxide, magnesium hydroxide, calcium hydroxide, zinc borate, kaolin clay, calcium carbonate and the like. These flame retardant aids may be used alone or in combination of two or more. These flame retardant aids may be treated with a silane coupling agent, a titanium coupling agent or the like. Among them, zinc borate and zinc stannate are preferable, and zinc stannate is more preferable.

[0037] <Aromatic vinyl copolymer (C)> The polyamide composition of the present invention contains an aromatic vinyl copolymer (C) (copolymer (C)). Here, the copolymer (C) contains an aromatic vinyl unit and an α,β-unsaturated dicarboxylic anhydride unit, and the glass transition temperature of the copolymer (C) is 140°C or higher. Such an aromatic vinyl is a compound having an aromatic ring and a vinyl group, and examples thereof include styrene, 2-methylstyrene, α-methylstyrene, p-methylstyrene and the like. Among them, styrene and α-methylstyrene are preferable, and styrene is more preferable. Examples of the α,β-unsaturated dicarboxylic acid anhydride include maleic anhydride, monoalkyl maleic anhydride having an alkyl group with 1 to 3 carbon atoms, dialkyl maleic anhydride having an alkyl group with 1 to 3 carbon atoms, and the like. Among them, at least one selected from the group consisting of maleic anhydride and monoalkyl maleic anhydride is preferable, at least one selected from the group consisting of maleic anhydride and citraconic anhydride is more preferable, and maleic anhydride is even more preferable.

[0038] The content of the α,β-unsaturated dicarboxylic acid anhydride unit in the copolymer (C) is preferably 18 to 50% by mass. When the content of the α,β-unsaturated dicarboxylic acid anhydride unit is 18% by mass or more, the α,β-unsaturated dicarboxylic acid anhydride unit in the copolymer (C) reacts with the carboxyl group terminal or amino group terminal of the polyamide (A), so that the viscosity of the polyamide composition increases, the melt tension improves, dripping is suppressed, and furthermore, the amount of carboxyl group terminals is reduced by this reaction, so that the decomposition of the polyamide (A) at high temperatures is also suppressed, and the flame retardancy of thin walls can be improved. When the content of the α,β-unsaturated dicarboxylic acid anhydride unit is 50% by mass or less, the viscosity of the polyamide composition does not become too high, and high flame retardancy and excellent moldability of thin walls can be achieved simultaneously. From this viewpoint, the content of the α,β-unsaturated dicarboxylic acid anhydride unit in the copolymer (C) is more preferably 19% by mass or more, even more preferably 20% by mass or more, also more preferably 40% by mass or less, even more preferably 30% by mass or less, even more preferably 28% by mass or less, and particularly preferably 25% by mass or less. The range of the content of the α,β-unsaturated dicarboxylic acid anhydride unit in the copolymer (C) is more preferably 18 to 40% by mass, even more preferably 19 to 30% by mass, even more preferably 20 to 28% by mass, and particularly preferably 20 to 25% by mass. The copolymer (C) may further have a structural unit other than the aromatic vinyl unit and the α,β-unsaturated dicarboxylic acid anhydride unit, but the total content of the aromatic vinyl unit and the α,β-unsaturated dicarboxylic acid anhydride unit in the copolymer (C) is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 100% by mass.

[0039] The glass transition temperature of copolymer (C) is 140°C or higher, preferably 145°C or higher, and more preferably 150°C or higher, from the viewpoint of flame retardancy and heat resistance in a thin wall, and is preferably 200°C or lower, more preferably 180°C or lower, and even more preferably 160°C or lower, from the viewpoint of suppressing thermal decomposition of the polyamide during melt molding. The glass transition temperature of copolymer (C) is preferably in the range of 140 to 200°C, more preferably 145 to 180°C, and even more preferably 150 to 160°C. The glass transition temperature of copolymer (C) is measured by the method described in the examples. From the viewpoint of flame retardancy and heat resistance in a thin wall, the weight average molecular weight (Mw) of copolymer (C) is preferably 10,000 or more, more preferably 20,000 or more, even more preferably 30,000 or more, still more preferably 40,000 or more, particularly preferably 50,000 or more, and is preferably 500,000 or less, more preferably 400,000 or less, even more preferably 300,000 or less, particularly preferably 200,000 or less. The weight average molecular weight (Mw) of copolymer (C) is more preferably 10,000 to 500,000, even more preferably 20,000 to 400,000, particularly preferably 30,000 to 300,000, and most preferably 50,000 to 200,000. The weight average molecular weight (Mw) is measured by gel permeation chromatography (GPC) in terms of polystyrene. The copolymer (C) may be a commercially available product or may be synthesized by a known method. The bonding form between the aromatic vinyl units and the α,β-unsaturated dicarboxylic anhydride units is not particularly limited and may be any of random polymerization, block polymerization, and graft polymerization. However, the bonding form of random polymerization or block polymerization is preferred because the effects of the present invention are more pronounced. The copolymer (C) is preferably one obtained by reacting an aromatic vinyl with an α,β-unsaturated dicarboxylic anhydride. Commercially available copolymers (C) include the DYLARK series (trade name, manufactured by NOVA Chemicals) and the XIRAN series (trade name, manufactured by Polyscope).

[0040] <Filler (D)> From the viewpoint of improving the flame retardancy, heat resistance, moldability, and mechanical strength of the polyamide composition of the present invention in thin-wall applications, it is further preferably to contain filler (D). As the filler (D), those having various forms such as fibrous, plate-like, needle-like, powdery, and cloth-like can be used. Specifically, fibrous fillers such as glass fiber, carbon fiber, aramid fiber, liquid crystal polymer (LCP) fiber, gypsum fiber, brass fiber, ceramic fiber, and boron whisker fiber; plate-like fillers such as glass flake, mica, and talc; needle-like fillers such as potassium titanate whisker, aluminum borate whisker, calcium carbonate whisker, magnesium sulfate whisker, wollastonite, sepiolite, zonnolite, and zinc oxide whisker; powdery fillers such as silica, alumina, barium carbonate, magnesium carbonate, aluminum nitride, boron nitride, potassium titanate, titanium oxide, aluminum silicate (kaolin, clay, pyrophyllite, bentonite), calcium silicate, magnesium silicate (attapulgite), aluminum borate, calcium sulfate, barium sulfate, magnesium sulfate, asbestos, glass beads, carbon black, graphite, carbon nanotube, silicon carbide, sericite, hydrotalcite, molybdenum disulfide, phenolic resin particles, crosslinked styrene-based resin particles, and crosslinked acrylic-based resin particles; cloth-like fillers such as glass cloth, etc. These may be used alone or in combination of two or more. The surfaces of these fillers (D) may be surface-treated with a silane coupling agent, a titanium coupling agent, a polymer compound such as an acrylic resin, a urethane resin, or an epoxy resin, or other low-molecular compounds for the purpose of enhancing the dispersibility in the polyamide (A) or enhancing the adhesiveness with the polyamide (A).

[0041] Among the fillers (D), at least one selected from the group consisting of fibrous fillers and acicular fillers is preferable because a molded article with low cost and high mechanical strength can be obtained. From the viewpoints of high strength and low cost, glass fiber is preferable as the filler (D), and an acicular filler is preferable from the viewpoint of obtaining a molded article with high surface smoothness. As the filler (D), at least one selected from the group consisting of glass fiber, wollastonite, potassium titanate whisker, calcium carbonate whisker, and aluminum borate whisker is preferable, at least one selected from the group consisting of glass fiber and wollastonite is more preferable, and glass fiber is even more preferable.

[0042] The average fiber length of the glass fiber is preferably 1 to 10 mm, more preferably 1 to 7 mm, and even more preferably 2 to 4 mm. Also, from the viewpoint of obtaining mechanical strength, the average fiber diameter of the glass fiber is preferably 6 to 20 μm, more preferably 6 to 15 μm. The average fiber length and average fiber diameter of the glass fiber can be determined by measuring the fiber lengths and fiber diameters of 400 arbitrarily selected glass fibers using image analysis by an electron microscope method and taking the respective weight average values. Also, in the polyamide composition or in a molded article made of the polyamide composition, the average fiber length and average fiber diameter of the glass fiber can be determined, for example, by dissolving the polyamide composition or the molded article in an organic solvent, extracting the glass fiber, and performing image analysis using an electron microscope method in the same manner as above.

[0043] <Other components> The polyamide composition of the present invention can further contain other components other than those described above, such as an anti-dripping agent such as polytetrafluoroethylene powder; an antioxidant such as a phenolic antioxidant or a phosphorus-based antioxidant; a mold release agent such as a polyolefin-based wax; a light stabilizer; a coloring agent; an antistatic agent; a crystal nucleating agent; a plasticizer; a lubricant, etc., if necessary.

[0044] <Content of each component in the polyamide composition> The content of polyamide (A) in the polyamide composition of the present invention is preferably 20 to 80% by mass. When the content of polyamide (A) is 20% by mass or more, molding is easy, and the heat resistance and mechanical properties of the obtained molded product are good. When it is 80% by mass or less, the flame retardancy is good. From this viewpoint, the content of the above polyamide (A) is more preferably 30 to 70% by mass, and even more preferably 35 to 60% by mass.

[0045] The content of the flame retardant (B) in the polyamide composition of the present invention is preferably 1 to 100 parts by mass with respect to 100 parts by mass of polyamide (A). When the content of the flame retardant (B) is 1 part by mass or more, the flame retardancy is improved. When the content of the flame retardant (B) is 100 parts by mass or less, it is possible to suppress the deterioration of the mechanical properties of the obtained polyamide composition. From this viewpoint, the content of the flame retardant (B) is more preferably 5 to 90 parts by mass, even more preferably 10 to 70 parts by mass, still more preferably 20 to 60 parts by mass, and particularly preferably 30 to 55 parts by mass with respect to 100 parts by mass of polyamide (A). When using a flame retardant aid, the content of the flame retardant aid is preferably 0.1 to 50 parts by mass, and more preferably 1 to 30 parts by mass with respect to 100 parts by mass of polyamide (A).

[0046] The content of the copolymer (C) in the polyamide composition of the present invention is 0.3 to 2.0% by mass based on the total content of the polyamide (A), the flame retardant (B) and the copolymer (C). Here, the constituent parts of the copolymer (C) that have reacted with the polyamide are also included in the calculation as the content of the copolymer (C) in the polyamide composition. When the content of the copolymer (C) is 0.3% by mass or more, the α,β-unsaturated dicarboxylic anhydride units in the copolymer (C) react with the carboxyl group terminals or amino group terminals of the polyamide (A), causing the polyamide composition to have an increased viscosity, improved melt tension, suppression of dripping, and further reduction of the amount of carboxyl group terminals due to the reaction, thereby suppressing the decomposition of the polyamide (A) at high temperatures and improving the flame retardancy of thin walls. Also, when the content of the copolymer (C) is 2.0% by mass or less, the viscosity of the polyamide composition does not become too high, and high flame retardancy of thin walls and excellent moldability can be achieved simultaneously. From this perspective, the content of the copolymer (C) is preferably 0.4% by mass or more, more preferably 0.5% by mass or more, still more preferably 0.6% by mass or more, even more preferably 0.7% by mass or more, particularly preferably 1.0% by mass or more, and most preferably 1.3% by mass or more, based on the total content of the polyamide (A), the flame retardant (B) and the copolymer (C). Also, it is more preferably 1.8% by mass or less, still more preferably 1.7% by mass or less, and even more preferably 1.6% by mass or less. As the range of the copolymer (C), 0.4 to 2.0% by mass is preferable, 0.5 to 1.8% by mass is more preferable, 0.6 to 1.8% by mass is still more preferable, 0.7 to 1.7% by mass is even more preferable, 1.0 to 1.7% by mass is particularly preferable, and 1.3 to 1.6% by mass is most preferable. The total content of the polyamide (A), the flame retardant (B) and the copolymer (C) in the polyamide composition of the present invention is not particularly limited, but from the viewpoints of flame retardancy, heat resistance and moldability of thin walls, it is preferably 40% by mass or more, more preferably 50% by mass or more, still more preferably 60% by mass or more.

[0047] When the polyamide composition of the present invention contains a filler (D), its content is preferably 1 to 100 parts by mass, more preferably 5 to 90 parts by mass, still more preferably 10 to 80 parts by mass, per 100 parts by mass of the polyamide (A), from the viewpoint of obtaining a molded article with high mechanical strength. When using the other components described above, the content of the other components in the polyamide composition of the present invention is preferably 30% by mass or less, more preferably 20% by mass or less, still more preferably 10% by mass or less.

[0048] The polyamide composition of the present invention can be prepared by mixing the above-described components according to a known method. More specific preparation methods include, for example, a method of adding each component during the polycondensation reaction of the polyamide (A), a method of dry blending the polyamide (A) and each component, and a method of melt-kneading each component using an extruder. Among these, the method of melt-kneading each component using an extruder is preferred because of the ease of operation and the ability to obtain a uniform composition. The extruder used at this time is preferably of a twin-screw type, and the melt-kneading temperature is preferably in the range from 5°C higher than the melting point of the polyamide (A) to 370°C or lower, more preferably in the temperature range from 10°C to 20°C higher than the melting point, from the viewpoint of achieving both good dispersibility and prevention of resin deterioration. There is no particular limitation on the form of the polyamide composition, and it can be made into pellets, for example.

[0049] The polyamide composition of the present invention has good moldability and can be molded into a molded article by a molding method generally employed for thermoplastic resin compositions, such as injection molding, extrusion molding, press molding, blow molding, calender molding, and casting molding. It is also possible to employ a molding method that combines the above-described molding methods. In particular, injection molding is preferred in terms of ease of molding, mass productivity, cost, etc. Further, it is also possible to perform composite molding of the polyamide composition of the present invention and another polymer. Furthermore, it is also possible to composite the polyamide composition of the present invention with a molded body made of metal, a fabric, or the like.

[0050] In the polyamide composition of the present invention, when the melt of the polyamide composition is injection-molded using a mold with a thickness of 0.5 mm and a width of 40 mm under the conditions of a cylinder temperature 20°C higher than the melting point of the polyamide (A), an injection pressure of 74 MPa, and a mold temperature of 140°C, the flow length is preferably 40 mm or more. Thereby, it is possible to achieve both high flame retardancy in thin-walled products and excellent moldability. From this perspective, the flow length is more preferably 45 mm or more, even more preferably 48 mm or more, still more preferably 50 mm or more, particularly preferably 53 mm or more, and preferably 70 mm or less, more preferably 65 mm or less, even more preferably 60 mm or less, still more preferably 56 mm or less, and may be 54 mm or less, or even 52 mm or less. The flow length is the average value of the flow lengths Ln of five test pieces obtained when five test pieces are produced using a mold with a thickness of 0.5 mm and a width of 40 mm under the above conditions, and is specifically measured by the method described in the examples.

[0051] The melt flow rate (MFR) of the polyamide composition of the present invention at a temperature of 320°C and a load of 2.16 kg is preferably 15 g / 10 min or less. Thereby, it is possible to achieve both high flame retardancy in thin-walled products and excellent moldability. From this perspective, the above melt flow rate is more preferably 1 to 13 g / 10 min, even more preferably 2 to 10 g / 10 min, and still more preferably 3 to 7 g / 10 min. The MFR can be determined by measuring the amount of molten resin (g / 10 min) flowing out from a standard die (diameter 2.095 mm, length 8.000 mm) at a temperature of 320°C and a load of 2.16 kg in accordance with JIS K 7210-1:2014.

[0052] [Molded article] The molded article of the present invention is made of the polyamide composition of the present invention, and through the molding process as described above, it can be used as various molded articles for electrical and electronic parts, automotive parts, industrial parts, fibers, films, sheets, household goods, and other arbitrary shapes and uses.

[0053] Examples of electrical and electronic components include connectors such as FPC connectors, BtoB connectors, card connectors, SMT connectors (coaxial connectors, etc.), memory card connectors, etc.; SMT relays; SMT bobbins; sockets such as memory sockets and CPU sockets; switches such as command switches and SMT switches; optical components such as optical fiber components and optical sensors; LED application components such as LED reflectors; and electronic substrates such as solar cell substrates, LED mounting substrates, flexible printed wiring boards, and resin molded circuit boards.

[0054] Examples of automotive parts include cooling parts such as thermostat housings, radiator tanks, radiator hoses, water outlets, water pump housings, and rear joints; intake and exhaust system parts such as intercooler tanks, intercooler cases, turbo duct pipes, EGR cooler cases, resonators, throttle bodies, intake manifolds, and tail pipes; fuel system parts such as fuel delivery pipes, gasoline tanks, quick connectors, canisters, pump modules, fuel pipes, oil strainers, lock nuts, and sealing materials; structural parts such as mount brackets, torque rods, and cylinder head covers; drive system parts such as bearing retainers, gear tensioners, headlamp actuator gears, slide door rollers, and clutch peripheral parts; brake system parts such as air brake tubes; in-vehicle electrical parts such as wire harness connectors, motor parts, sensors, ABS bobbins, combination switches, and in-vehicle switches in the engine room; and interior and exterior parts such as slide door dampers, door mirror stays, door mirror brackets, inner mirror stays, roof rails, engine mount brackets, air cleaner inlet pipes, door checkers, plastic chains, emblems, clips, breaker covers, cup holders, airbags, fenders, spoilers, radiator supports, radiator grilles, louvers, air scoops, hood bulges, back doors, and fuel sender modules.

[0055] Industrial parts include, for example, gas pipes, oil field exploration pipes, hoses, anti - termite cables (communication cables, patch cables, etc.), paint parts of powder - coated products (inner coating of water pipes, etc.), subsea oil field pipes, pressure - resistant hoses, hydraulic tubes, paint tubes, fuel pumps, separators, supercharger ducts, butterfly valves, conveyor roller bearings, railway sleeper spring supports, outboard engine covers, generator engine covers, irrigation valves, large switches, monofilaments (extruded filaments) such as fishing nets, etc.

[0056] Fibers include, for example, airbag base fabrics, heat - resistant filters, reinforcing fibers, bristles for brushes, fishing lines, tire cords, artificial turf, carpets, fibers for seat covers, etc.

[0057] Films and sheets include, for example, heat - resistant adhesive tapes such as heat - resistant masking tapes and industrial tapes; magnetic tape materials for magnetic tapes such as cassette tapes, data storage magnetic tapes for digital data storage, video tapes, etc.; food packaging materials such as pouches for retort foods, individual packages for confectionery, packages for processed meat products, etc.; electronic component packaging materials such as packaging for semiconductor packages, etc.

[0058] Among them, the polyamide composition of the present invention is particularly excellent in flame retardancy, heat resistance and moldability in thin - walled parts, and thus can be suitably used for electric and electronic parts. It can be suitably used for electric and electronic parts including the SMT process, more specifically, SMT - compatible connectors, SMT relays, SMT bobbins, sockets, command switches, SMT switches, etc.

Examples

[0059] Hereinafter, the present invention will be described in more detail using examples and comparative examples, but the present invention is not limited to the following examples. In addition, each evaluation in the examples and comparative examples was carried out according to the methods shown below.

[0060] (Melting point) The melting point of polyamide (A) was determined as the peak temperature of the melting peak that appeared when the temperature was raised from 30°C to 360°C at a rate of 10°C / min under a nitrogen atmosphere using a differential scanning calorimeter "DSC822" manufactured by Mettler Toledo Co., Ltd. When there were multiple melting peaks, the peak temperature of the melting peak on the highest temperature side was taken as the melting point.

[0061] (Limiting viscosity [η]) Using concentrated sulfuric acid (concentration: 98% by mass) as a solvent, polyamide (A) concentrated sulfuric acid solutions (sample solutions) were prepared so that the solution concentrations c were 0.05, 0.1, 0.2, and 0.4 g / dl, respectively. In a constant temperature bath at 30°C, the flow-down time t0 of the solvent and the flow-down time t1 of each concentration of the sample solution were measured using an Ubbelohde viscometer. The inherent viscosity (η inh ) was calculated by the following formula, and the value obtained by extrapolating the inherent viscosity (η inh ) to a concentration of 0 was taken as the limiting viscosity [η] of polyamide (A). η inh (dl / g) = [ln(t1 / t0)] / c [In the formula, t0 represents the flow-down time (seconds) of the solvent, t1 represents the flow-down time (seconds) of the sample solution, and c represents the solution concentration (g / dl).]

[0062] (Glass transition temperature) The glass transition temperature of copolymer (C) was measured by a method in accordance with JIS K 7121:1987.

[0063] (Flame retardancy) The flame retardancy was evaluated in accordance with the provisions of the UL-94 standard. Using the polyamide compositions obtained in each of the examples and comparative examples, injection molding was performed at a cylinder temperature approximately 20 °C higher than the melting point of the polyamide (mold temperature: 140 °C) to obtain test pieces with a thickness of 0.3 mm, a width of 13 mm, and a length of 125 mm. Next, the upper end of the test piece was clamped to fix the test piece vertically, and a predetermined flame was applied to the lower end for 10 seconds and then removed, and the combustion time (first time) of the test piece was measured. Immediately after extinguishing the fire, the flame was applied to the lower end again and then removed, and the combustion time (second time) of the test piece was measured. The same measurement was repeated for 5 test pieces, and a total of 10 data were obtained, including 5 data for the first combustion time and 5 data for the second combustion time. The sum of the 10 data was designated as T, the maximum value among the 10 data was designated as M, and the evaluation was carried out according to the following evaluation criteria. Also, the presence or absence of drips during flame contact was visually confirmed. 〔Evaluation Criteria〕 V-0: T is 50 seconds or less, M is 10 seconds or less, it does not burn up to the clamp, and even if the molten material with a flame drops, it does not ignite the cotton 12 inches below. V-1: T is 250 seconds or less, M is 30 seconds or less, it does not burn up to the clamp, and even if the molten material with a flame drops, it does not ignite the cotton 12 inches below. V-2: T is 250 seconds or less, M is 30 seconds or less, it does not burn up to the clamp, and the molten material with a flame drops and ignites the cotton 12 inches below.

[0064] (Amount of deformation) The amount of deformation of the length of the test piece on which the flame retardancy evaluation was carried out was evaluated by the following method. Excluding the test pieces in which drips occurred during the flame retardancy evaluation, the lengths of n test pieces in which no drips occurred before and after the flame retardancy evaluation were measured, and the amount of deformation was calculated according to the following formula. Also, when drips occurred in all the test pieces, the amount of deformation was designated as ×. The smaller the numerical value of the amount of deformation, the better the flame retardancy. Amount of deformation = 〔(Sum of the lengths of n test pieces after the flame retardancy evaluation) - (Sum of the lengths of n test pieces before the flame retardancy evaluation)〕 / n

[0065] (Moldability (flow length)) Using the injection molding machine UH-1000 (clamping force 80 t) manufactured by Nissei Plastic Industrial Co., Ltd., under the conditions of a cylinder temperature 20 °C higher than the melting point of polyamide (A), an injection pressure of 74 MPa, and a mold temperature of 140 °C, five test pieces with a thickness of 0.5 mm and a width of 40 mm were produced one by one using a mold. The average value of the flow lengths Ln of the five produced test pieces was calculated and used as the flow length of the polyamide composition. This was used as an index for evaluating the moldability. The higher the numerical value of the flow length, the better the moldability, and if the flow length is 40 mm or more, it can be put into practical use.

[0066] Production Example 1 (Production of Polyamide PA1) 7882.0 g of terephthalic acid, 7742.9 g of a diamine mixture of 1,9-nonanediamine:2-methyl-1,8-octanediamine = 85:15 (molar ratio), 280.8 g of benzoic acid as a terminal blocking agent, 16.0 g of sodium hypophosphite monohydrate, and 4 L of distilled water were placed in an autoclave with an internal volume of 40 L and purged with nitrogen. The internal temperature was raised to 200 °C over 2 hours. At this time, the autoclave was pressurized up to 2 MPa. Then, the internal temperature was maintained at 215 °C, and water vapor was gradually removed while maintaining the pressure at 2 MPa, and the reaction was carried out for 2 hours. Next, the pressure was reduced to 1.2 MPa over 30 minutes to obtain a prepolymer. This prepolymer was pulverized to a size of 6 mm or less and dried at 120 °C under reduced pressure for 12 hours. This was subjected to solid-phase polymerization at a temperature of 230 °C and a pressure of 13.3 Pa for 10 hours to obtain polyamide PA1 with a melting point of 306 °C and an intrinsic viscosity [η] = 0.93 dl / g.

[0067] Examples 1 to 9, Comparative Examples 1 to 2 The components other than the filler (D), namely the polyamide (A), flame retardant (B), copolymer (C), flame retardant aid, and other components, were supplied from the hopper at the uppermost stream part of a twin-screw extruder (screw diameter: 26 mmφ, L / D = 46, rotation speed: 150 rpm, discharge rate: 10 kg / h) manufactured by Toshiba Machine Co., Ltd., and the filler (D) was supplied from a side feeder and melt-kneaded at 320°C. The melt-kneaded polyamide composition was extruded in a strand shape, cooled, and then cut to obtain pellets of the polyamide composition. Using the obtained pellets, test pieces of a predetermined shape were produced according to the method described above, and various physical properties were evaluated. The results are shown in Table 1.

[0068] In addition, each component shown in Table 1 is as follows. 〔Polyamide (A)〕 · Polyamide PA1 obtained in Production Example 1 〔Flame retardant (B)〕 · Brominated flame retardant B1: manufactured by Chemtura Corporation, trade name "Firemaster CP-44HF" (glycidyl methacrylate-modified polybrominated styrene) · Phosphorus-based flame retardant B2: manufactured by Clariant Corporation, trade name "Exolit OP1230" 〔Copolymer (C)〕 · Copolymer C1: manufactured by Polyscope, trade name "XIRAN SZ 23110" (styrene-maleic anhydride copolymer, maleic anhydride content: 23% by mass, glass transition temperature: 150°C, weight average molecular weight (Mw): 110,000) · Copolymer C2: manufactured by Polyscope, trade name "XIRAN SZ 28065" (styrene-maleic anhydride copolymer, maleic anhydride content: 28% by mass, glass transition temperature: 165°C, weight average molecular weight (Mw): 65,000) · Copolymer C3: manufactured by Polyscope, trade name "XIRAN SZ 26180" (styrene-maleic anhydride copolymer, maleic anhydride content: 26% by mass, glass transition temperature: 160°C, weight average molecular weight (Mw): 180,000) 〔Filler (D)〕 · Filler D1: Manufactured by Nitto Boseki Co., Ltd., trade name "CS-3G-225S" (glass fiber, cross-sectional shape: round, average fiber diameter: 9.5 μm, average fiber length: 3 mm) 〔Flame Retardant Aid〕 · Flame Retardant Aid 1: Manufactured by Nippon Light Metal Co., Ltd., trade name "Flamtard S" (zinc stannate)

[0069] 〔Other Components〕 · Anti-Dripping Agent: Manufactured by Mitsui DuPont Fluorochemicals Co., Ltd., trade name "640-J" (polytetrafluoroethylene powder) · Antioxidant: Manufactured by Sumitomo Chemical Co., Ltd., trade name "Sumilizer GA-80" (3,9-bis{1,1-dimethyl-2-[β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl}-2,4,8,10-tetraoxaspiro[5.5]undecane) · Release Agent: Manufactured by Mitsui Chemicals, Inc., trade name "Hiwax 200P" (polyolefin wax) · Crystal Nucleating Agent: Manufactured by Fuji Talc Industry Co., Ltd., trade name "ML112" (talc)

[0070]

Table 1

[0071] As shown in Table 1, according to the polyamide composition of the present invention, it can be seen that molded articles excellent in flame retardancy for thin walls can be obtained, and they are also excellent in heat resistance and moldability.

Claims

1. A polyamide composition containing a polyamide (A) having a melting point of 280°C or higher, a flame retardant (B), and an aromatic vinyl copolymer (C), wherein the flame retardant (B) is a halogen-based flame retardant, the aromatic vinyl copolymer (C) contains a structural unit derived from an aromatic vinyl and a structural unit derived from an α,β-unsaturated dicarboxylic anhydride, and the glass transition temperature of the aromatic vinyl copolymer (C) is 140°C or higher and 165°C or lower, the content of the structural unit derived from the α,β-unsaturated dicarboxylic anhydride in the aromatic vinyl copolymer (C) is 18 to 28% by mass, and the content of the aromatic vinyl copolymer (C) is 0.3 to 2.0% by mass based on the total content of the polyamide (A), the flame retardant (B), and the aromatic vinyl copolymer (C).

2. The polyamide composition according to claim 1, wherein the polyamide (A) is a semi-aromatic polyamide.

3. In the semi-aromatic polyamide, more than 50 mol% of the structural units derived from the dicarboxylic acid constituting the semi-aromatic polyamide are structural units derived from an aromatic dicarboxylic acid, and more than 50 mol% of the structural units derived from the diamine constituting the semi-aromatic polyamide are structural units derived from an aliphatic diamine having 4 to 18 carbon atoms. The polyamide composition according to claim 2.

4. The polyamide composition according to claim 3, wherein the aliphatic diamine is at least one selected from the group consisting of 1,6-hexanediamine, 1,9-nonanediamine, 2-methyl-1,8-octanediamine, and 1,10-decanediamine.

5. The polyamide composition according to any one of claims 1 to 4, wherein the flame retardant (B) is a bromine-based flame retardant.

6. The polyamide composition according to any one of claims 1 to 5, wherein the structural unit derived from the aromatic vinyl contains a structural unit derived from at least one selected from the group consisting of styrene and α-methylstyrene.

7. The polyamide composition according to any one of claims 1 to 6, wherein the α,β-unsaturated dicarboxylic anhydride is at least one selected from the group consisting of maleic anhydride and monoalkyl maleic anhydride having an alkyl group with 1 to 3 carbon atoms.

8. The polyamide composition according to any one of claims 1 to 7, wherein the weight average molecular weight (Mw) of the aromatic vinyl copolymer (C) is from 10,000 to 500,000.

9. The polyamide composition according to any one of claims 1 to 8, further containing a filler (D).

10. The polyamide composition according to any one of claims 1 to 9, wherein the polyamide composition is obtained by melt-kneading polyamide (A), a flame retardant (B), and an aromatic vinyl copolymer (C).

11. The polyamide composition according to claim 9, wherein the polyamide composition is obtained by melt-kneading polyamide (A), a flame retardant (B), an aromatic vinyl copolymer (C), and the filler (D).

12. A molded article comprising the polyamide composition according to any one of claims 1 to 11.

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