TWI891962B - Flame retardant polyamide resin composition and molded products thereof - Google Patents

Abstract

The present invention is to provide a flame-retardant polyamide resin composition that exhibits UL94V-0 flame retardancy over a wide range of thicknesses, exhibits minimal flame retardant leakage, and exhibits excellent heat discoloration resistance, formability, and snap-fit properties. This flame-retardant polyamide resin composition comprises a polyamide resin (A) and melamine cyanurate (B), wherein the composition comprises, per 100 parts by weight of the combined components (A) and (B), 90-98 parts by weight of the polyamide resin (A) and 2-10 parts by weight of the melamine cyanurate (B). In the polyamide resin (A), the polyamide 66 resin (A1) is present in an amount of 100 parts by weight. The ratio of polyamide 6 resin (A2) is 55-85% by mass; the ratio of polyamide 6 resin (A2) is 15-45% by mass; and the following ratios are contained per 100 parts by mass of the total of components (A) and (B): 0.01-1 part by mass of a phosphorus-based antioxidant (C), 0.01-1 part by mass of a hindered phenol-based antioxidant (D), and 0.1-1 part by mass of a fatty acid metal salt lubricant (E) having 22 or fewer carbon atoms.

Description

Flame retardant polyamide resin composition and molded products thereof

The present invention relates to a non-halogen flame-retardant polyamide resin composition. More specifically, it relates to a non-halogen flame-retardant polyamide resin composition having high flame retardancy, good snap-fit properties, and excellent heat discoloration resistance.

Polyamide resins are used in various fields, including electrical and electronic components, and automotive parts, due to their excellent mechanical, electrical, and chemical resistance properties. In these fields, when flame retardancy is required with a non-reinforced, non-halogen flame retardant, melamine cyanurate is often used (e.g., Patents 1 and 2). However, melamine cyanurate has the following disadvantages: poor dispersibility in polyamide resins, decreased mechanical properties of polyamide resins with increased incorporation, exudation, thermal decomposition into melamine and cyanuric acid, which readily sublimate, the formation of silver streaks on the surface of molded parts during molding due to the sublimated melamine and cyanuric acid, and the tendency to contaminate mold surfaces.

In recent years, with the increasing demands placed on electrical and electronic components, automotive parts, and other products, flame retardancy levels exceeding UL94 V-0 are being required for various thicknesses. Furthermore, there is a desire for even higher levels of flame retardant resistance, heat discoloration resistance, formability, and snap-fit properties. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Publication No. 58-25379 [Patent Document 2] Japanese Patent Publication No. 58-35541

[The problem that the invention aims to solve]

This invention aims to provide a flame-retardant polyamide resin composition that exhibits UL94V-0 flame retardancy over a wide range of thicknesses, minimizes flame retardant leakage, and exhibits excellent heat discoloration resistance, formability, and snap-fit properties. [Solution]

The inventors of this case have conducted intensive research to solve the above-mentioned problems and have completed this invention.

That is, the present invention has the following constitution. [1] A flame retardant polyamide resin composition comprising a polyamide resin (A) and melamine cyanurate (B); relative to 100 parts by weight of the total of the above components (A) and (B), the composition comprises: 90-98 parts by weight of the polyamide resin (A) and 2-10 parts by weight of the melamine cyanurate (B), a phosphorus-based antioxidant (C) 0.01~1 mass part, hindered phenol antioxidant (D) 0.01~1 mass part, and fatty acid metal salt lubricant (E) with a carbon number of 22 or less; the above-mentioned polyamide resin (A) contains polyamide 66 resin (A1) 55~85 mass% and polyamide 6 resin (A2) 15~45 mass%. [2] The flame retardant polyamide resin composition as described in [1], wherein the above-mentioned fatty acid metal salt lubricant (E) is a metal salt of stearic acid. [3] A molded article composed of the flame retardant polyamide resin composition as described in any one of [1] to [2]. [4] The molded product as described in [3], wherein the molded product is any one of a ferrite core cover, an SC gate, a cable tie, and an electric wiring protection member. [Effects of the Invention]

The flame-retardant polyamide resin composition of the present invention not only exhibits excellent heat discoloration resistance and formability, but also maintains UL94V-0 flame retardancy over a wide range of thicknesses without significantly compromising breaking strength and toughness.

The present invention is described in detail below. [Polyamide Resin (A)] The polyamide resin (A) in the present invention is not particularly limited as long as it is a polymer having an amide bond (-NHCO-) in the main chain. The polyamide resin (A) is preferably crystalline, and examples thereof include polyamide 6 (PA6), polyamide 66 (PA66), polyamide 46 (PA46), polyamide 11 (PA11), polyamide 12 (PA12), polyamide 610 (PA610), polyamide 612 (PA612), poly(m-xylene adipate) (PAMXD6), hexamethylenediamine-terephthalic acid polymer (PA6T), and hexamethylenediamine-terephthalic acid and adipic acid polymer (PA6T/66). , hexamethylenediamine-terephthalic acid and ε-caprolactam copolymer (PA6T/6), trimethylhexamethylenediamine-terephthalic acid polymer (PATMD-T), meta-xylylenediamine, adipic acid and isophthalic acid copolymer (PAMXD6/MXDI), trihexamethylenediamine, terephthalic acid and ε-caprolactam copolymer (PATMDT/6), diaminodicyclohexylmethane, isophthalic acid and lauryl lactam copolymer, and other crystalline polyamide resins, or mixtures thereof, but are not limited thereto.

The blending amount (content) of the polyamide resin (A) is 90-98 parts by mass, based on 100 parts by mass of the total of the polyamide resin (A) and melamine cyanurate (B). By blending the polyamide resin (A) within this range, the leakage of the flame retardant can be suppressed and the high flame retardancy of the composition can be maintained. The blending amount (content) of the polyamide resin (A) is preferably 92-96 parts by mass, more preferably 93-95 parts by mass. In the flame-retardant polyamide resin composition of the present invention, the blending amount of each component is directly used as the content.

Considering the advantages of excellent moldability, melt flowability, and flame retardancy, the ideal polyamide resin (A) in the present invention is a mixture of polyamide 66 resin (A1) and polyamide 6 resin (A2).

The polyamide 66 resin (A1) of the present invention can be obtained, for example, by polycondensation of adipic acid and hexamethylenediamine as raw materials. The relative viscosity of the polyamide 66 resin (A-1), measured in accordance with JIS K6810 at a concentration of 1% in 98% sulfuric acid at 25°C, is preferably 2.2 to 3.5. A relative viscosity below 2.2 can result in reduced mechanical properties, while a viscosity exceeding 3.5 can lead to insufficient melt flowability. The relative viscosity of the polyamide 66 resin (A1) is preferably 2.3 to 3.0. Alternatively, the polyamide 66 resin (A1) may be prepared by mixing polyamide 66 resins having different relative viscosities and adjusting the relative viscosity to an appropriate range.

The terminal amino group concentration of the polyamide 66 resin (A1) is not particularly limited, but is preferably 50-90 eq/ton. Considering heat discoloration resistance, it is more preferably 60-80 eq/ton.

The blending amount of polyamide 66 resin (A1) is preferably 55-85 parts by mass per 100 parts by mass of polyamide resin (A). If the blending amount of polyamide 66 resin (A1) exceeds 85 parts by mass, the hinge properties (snap-fit properties) will decrease, while if it is less than 50 parts by mass, the moldability will tend to decrease. The blending amount of polyamide 66 resin (A1) is preferably 60-80 parts by mass, based on the balance between snap-fit properties and moldability.

The polyamide 6 resin (A2) in the present invention is obtained by polycondensation using ε-caprolactam as a raw material. The relative viscosity of the polyamide 6 resin (A2), measured in accordance with JIS K6810 at a concentration of 1% in 98% sulfuric acid at 25°C, is preferably 1.5 to 4.0. A relative viscosity below 1.5 may degrade mechanical properties, while a viscosity exceeding 3.6 may impair flame retardancy and fluidity. The relative viscosity of the polyamide 6 resin (A2) is preferably 1.8 to 3.6. Alternatively, the polyamide 6 resin (A-2) may be prepared by mixing polyamide 6 resins having different relative viscosities and adjusting the relative viscosity to an appropriate range.

The terminal amino group concentration of the polyamide 6 resin (A2) is not particularly limited, but is preferably 50-90 eq/ton. Considering heat discoloration resistance, it is more preferably 60-80 eq/ton.

The blending amount of polyamide 6 resin (A2) is preferably 15-45 parts by mass per 100 parts by mass of polyamide resin (A). If the blending amount of polyamide 6 resin (A2) is less than 15 parts by mass, the hinge properties (snap-fit properties) are likely to be reduced, while if it exceeds 45 parts by mass, the moldability is likely to be reduced. The blending amount of polyamide 6 resin (A2) is preferably 20-40 parts by mass, based on the balance between snap-fit properties and moldability.

To improve the appearance of the molded article, an amorphous polyamide resin (A3) may also be incorporated. Examples of amorphous polyamide resins include polymers, copolymers, or blends obtained by polycondensing diamines such as 4,4'-diamino-3,3'-dimethyldicyclohexylmethane (CA), 4,4'-diaminodicyclohexylmethane (PACM), m-xylylenediamine (MXD), trimethylhexamethylenediamine (TMD), isophoronediamine (IA), 4,4'-diaminodicyclohexylpropane (PACP), and hexamethylenediamine with dicarboxylic acids such as terephthalic acid, isophthalic acid, adipic acid, sebacic acid, and dodecanedicarboxylic acid, and lactamides such as caprolactam and laurolactamide. The blending amount of the amorphous polyamide resin (A3) is preferably 0-15 parts by weight, based on the balance between snap-fit bonding properties and moldability.

[Melamine Cyanurate (B)] The melamine cyanurate (B) in the present invention can suitably be an equimolar reaction product of cyanuric acid and melamine. Furthermore, a portion of the amino or hydroxyl groups in the melamine cyanurate may be substituted with other substituents. Melamine cyanurate can be obtained by, for example, mixing an aqueous solution of cyanuric acid and an aqueous solution of melamine, reacting them under stirring at 90-100°C, and filtering the resulting precipitate. The resulting solid can be used directly, but is preferably pulverized for use as needed. The particle size is not particularly limited; however, from the perspectives of flame retardancy and toughness, the average particle size is preferably 0.5-20 μm, more preferably 1-15 μm.

The blending amount (content) of melamine cyanurate (B) is 2 to 10 parts by mass per 100 parts by mass of the total of the polyamide resin (A) and melamine cyanurate (B). From the perspective of flame retardancy, the blending amount is 2 parts by mass or more, and from the perspective of snap-fit bonding and bleeding, the blending amount is 10 parts by mass or less. The blending amount is preferably 3 to 9 parts by mass, and more preferably 4 to 8 parts by mass.

[Phosphorus-based antioxidant (C)] The phosphorus-based antioxidant (C) in the present invention may be an inorganic compound or an organic compound, and is not particularly limited. Suitable phosphorus-based compounds include inorganic phosphates such as monosodium phosphate, disodium phosphate, trisodium phosphate, sodium phosphite, calcium phosphite, magnesium phosphite, and manganese phosphite, triphenyl phosphite, trioctadecyl phosphite, tridecyl phosphite, triisodecyl phosphite, trisnonylphenyl phosphite, diphenylisodecyl phosphite, diphenylalkyl phosphite, phenyldialkyl phosphite, tris(nonyl) ... phenyl) phosphite, trilauryl phosphite, di-stearyl pentaerythritol diphosphite, tris(2,4-di-tert-butylphenyl) phosphite, diisodecyl pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, diisodecyl pentaerythritol diphosphite Ester, bis(2,4-di-tert-butyl-6-methylphenyl)pentylathitol diphosphite, bis(2,4,6-tris(tert-butylphenyl))pentylathitol diphosphite, tristearyl sorbitol triphosphite, tetrakis(2,4-di-tert-butylphenyl)-4,4'-biphenyl diphosphonite, 6-isooctyloxy-2,4,8,10-tetra-tert-butyl-12H-dibenzo[d ,g]-1,3,2-dioxaphosphinooctacycle, 6-fluoro-2,4,8,10-tetra-tert-butyl-12-methyl-dibenzo[d,g]-1,3,2-dioxaphosphinooctacycle, bis(2,4-di-tert-butyl-6-methylphenyl)methylphosphite, and bis(2,4-di-tert-butyl-6-methylphenyl)ethylphosphite can be blended to improve heat discoloration resistance.

The phosphorus-based antioxidant (C) is preferably a phosphite compound. Among the phosphite compounds, a compound having a pentaerythritol diphosphite skeleton is preferred. Specifically, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite (ADK STAB PEP-36, molecular weight 633), bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite (ADK STAB PEP-24G, molecular weight 604), distearylpentaerythritol diphosphite (ADK STAB PEP-8, molecular weight 733), and bis(nonylphenyl)pentaerythritol diphosphite (ADK STAB PEP-4C, molecular weight 633), which have a pentaerythritol diphosphite backbone and a molecular weight of approximately 600-800, are particularly desirable because they do not reduce flame retardancy, can further improve mold release properties, and also provide suitable snap-fit bonding properties.

The blending amount (content) of the phosphorus-based antioxidant (C) is 0.01 to 1 part by mass per 100 parts by mass of the combined polyamide resin (A) and melamine cyanurate (B). This range of phosphorus-based antioxidant (C) content can suppress discoloration during extrusion and prevent reoxidative degradation caused by the induction of phosphorus-derived free radicals. The blending amount of the phosphorus-based antioxidant (C) is preferably 0.1 to 0.5 parts by mass.

[Hindered Phenol Antioxidant (D)] Hindered phenol antioxidants (D) in the present invention include N,N'-hexamethylene-bis-3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionamide, bis(3,3-bis-(4'-hydroxy-3'-tert-butylphenyl) butyrate) glycol, 2,1'-thioethyl bis(3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate), 4,4'-butylene-bis(3-methyl-6-tert-butylphenol), triethylene glycol-3-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate (SONGNOX 2450, molecular weight 633), and mixtures of two or more thereof may also be used.

The blending amount (content) of the hindered phenolic antioxidant (D) is 0.01-1 part by mass per 100 parts by mass of the combined polyamide resin (A) and melamine cyanurate (B). By blending the hindered phenolic antioxidant (D) within this range, the appropriate amount of coordination bonds within the polyamide composition can be adjusted to prevent oxidative degradation over time. The blending amount of the hindered phenolic antioxidant (D) is preferably 0.1-0.5 parts by mass.

[Metal Salt-Based Lubricant of Fatty Acids with 22 or Less Carbon Dioxide (E)] Metal salt-based lubricants of fatty acids with 22 or less carbon atoms (E) in the present invention include metal salts of fatty acids such as stearic acid, palmitic acid, and behenic acid. The use of metal salt-based lubricants of fatty acids with 22 or less carbon atoms not only improves release properties but also prevents ignition of flammable gases because the combustion gas generated by the fatty acid during combustion begins at a temperature close to that of non-flammable gases generated by the decomposition of melamine cyanurate. This tends to enhance flame retardancy.

Metal salts of aliphatic carboxylic acids with 18 or fewer carbon atoms are preferred. Alkaline metal or alkaline earth metal salts of stearic acid, palmitic acid, and the like are particularly preferred due to their combined release and flame retardancy. Examples of such alkaline metals include lithium, sodium, magnesium, and calcium salts. Alkaline metal or alkaline earth metal salts of stearic acid are particularly preferred because, when burned, the flammable gas derived from the fatty acid decomposition of the metal salt and the non-flammable gas generated from the decomposition of melamine cyanurate begin to be generated at the same temperature. This improves release properties without compromising flame retardancy, making them the most preferred choice.

The blending amount (content) of the fatty acid metal salt lubricant (E) should be 0.1-1 part by mass per 100 parts by mass of the polyamide resin (A) and melamine cyanurate (B). Exceeding 1 part by mass may reduce flame retardancy. The blending amount of the fatty acid metal salt lubricant (E) is preferably 0.2-0.8 parts by mass.

[Other Ingredients] In addition to the aforementioned (A), (B), (C), (D), and (E), the flame-retardant polyamide resin composition of the present invention may also contain other ingredients, such as colorants such as pigments and dyes, thermal stabilizers, weathering agents, nucleating agents, plasticizers, debonding agents, antistatic agents, and other additives, as well as other resin polymers, within the scope of not impairing the purpose of the present invention. The flame-retardant polyamide resin composition of the present invention preferably comprises at least 80% by mass of the aforementioned components (A), (B), (C), (D), and (E), preferably at least 90% by mass, and even more preferably at least 95% by mass.

Suitable molded parts obtained using the flame-retardant polyamide resin composition of the present invention include, specifically, connectors, conduit, circuit breakers, electromagnetic switches, brackets, plugs, sockets, switches, cassettes, and covers used in the electrical, electronic, and automotive fields. More specifically, these molded parts include ferrite core covers, SC locks, cable ties, and wiring protection components that require heat discoloration resistance and snap-fit properties.

The method for producing the flame-retardant polyamide resin composition of the present invention is not particularly limited. Conventional single-screw extruders, double-screw extruders, pressure kneaders, and the like can be used as the kneading apparatus. However, a double-screw extruder is particularly preferred in the present invention. In one embodiment, the above-mentioned (A), (B), (C), (D), and (E), along with a pigment depending on the intended use, are mixed and fed into a double-screw extruder. By uniformly kneading the mixture in a double-screw extruder, a polyamide resin composition with high toughness and excellent flame retardancy can be produced. The kneading temperature in the double-screw extruder is preferably 220-300°C, and the kneading time is approximately 2-15 minutes. [Examples]

The present invention is described in more detail below with reference to embodiments, but the present invention is not limited to these embodiments.

The following components were used. Polyamide resin (A); A1-1: Polyamide 66 (RV = 2.8) Vydyne 21Z (Ascend), melting point 265°C A1-2: Polyamide 66 (RV = 2.4) EPR24 (Shanghai Shenma Plastics Technology Co., Ltd.), melting point 265°C A2-1: Polyamide 6 (RV = 2.0) M2000 (MEIDA), melting point 225°C A2-2: Polyamide 6 (RV = 3.6) ZISAMIDE TP6603 (Jisheng), melting point 225°C

Melamine cyanurate (B); B: MC6000 (manufactured by Nissan Chemical Co., Ltd.)

Phosphorus-based antioxidant (C); C: ADK STABPEP-36 (manufactured by ADEKA Co., Ltd.)

Hindered phenol antioxidant (D); D: SONGNOX 2450 (manufactured by Songwon International Japan)

Fatty acid metal salt lubricant (E); E1: Magnesium stearate N.P.-1500S (manufactured by Tamnan Chemical Industry Co., Ltd.) Other stripping agents; E2: Calcium octadecanoate CS-8-CP (manufactured by Nitto Kasei Industry Co., Ltd.) E3: Fatty acid ester LICOLUB WE-40 (manufactured by Clariant Japan Co., Ltd.)

[Examples 1-12, Comparative Examples 1-7] Evaluation samples were prepared by measuring the raw materials according to the blending ratios of the polyamide resin composition shown in Table 1, mixing them using a rotary drum, and then feeding them into a biaxial extruder. The biaxial extruder temperature was set at 250°C to 300°C, and the mixing time was set at 5 to 10 minutes. The resulting pellets were then formed into various evaluation samples using an injection molding machine. The cylinder temperature of the injection molding machine was set at 250°C to 280°C, and the mold temperature was set at 80°C.

The various evaluation methods are as follows. The evaluation results are shown in Table 1. 1. Relative Viscosity [RV] of Polyamide Resin (98% Sulfuric Acid Solution Method) Using an Oobleck viscometer, measurements were performed at 25°C using a 98% by mass sulfuric acid solution at a polyamide resin concentration of 1 g/dL. 2. Melting Point of Polyamide Resin Using a Seiko Instruments EXSTAR 6000 differential scanning calorimeter (DSC) at a heating rate of 20°C/min, the melting point was determined as the peak temperature of the endothermic peak. 3. Snap-fit Properties (Tensile Strength, Tensile Elongation): Measured in accordance with ISO 527, tensile strength (ultimate strength) and tensile elongation (tensile strain at break) were determined. 4. Flammability: Measured according to the UL94 vertical flame test. V-0 indicates the highest flame retardancy. 5. Exudation: 2mm thick, 100mm x 100mm molded articles were placed in a constant temperature and humidity chamber set at 80°C and 95% RH for 96 hours, repeated at least twice. The articles were then returned to room temperature and the surface was visually inspected using a stereo microscope for the presence of precipitates. 6. Thermochromicity: The color difference (ΔE) between pellets after 8 hours in an oven at 120°C and before treatment was calculated. 7. Formability: Using a mold equipped with a demolding force measuring device, mold the part at the above molding temperature conditions. Measure the demolding force from the 31st to the 35th injection and calculate the demolding resistance value.

[Table 1] Differentiation Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Example 11 Example 12 Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Comparative example 5 Comparative example 6 Comparative example 7 Composition (mass) A1-1: Polyamide 66 54 55 53 36 18 54 54 54 54 56 44 54 60 50 30 54 54 53 54 A1-2: Polyamide 66 18 19 17 36 54 18 18 18 18 twenty three 15 18 20 16 10 18 18 17 18 A2-1: Polyamide 6 twenty two twenty two twenty two twenty two twenty two twenty two twenty two twenty two twenty two 15 35 19 twenty two 54 twenty two twenty two 20 twenty two A2-2: Polyamide 6 twenty two B: MC6000 6 4 8 6 6 6 6 6 6 6 6 6 1 12 6 6 6 10 6 C: Phosphorus antioxidant 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 D: Hindered phenol antioxidant 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 E1: Magnesium stearate 0.6 0.6 0.6 0.6 0.6 0.1 0.2 0.4 0.8 0.6 0.6 0.6 0.6 0.6 0.6 E2: Calcium octacosanate 0.6 0.2 0.6 E3: Fatty esters 0.6 Snap-fit Tensile strength (MPa) 78 80 76 78 76 80 81 83 83 75 75 81 82 85 76 80 81 84 79 Tensile elongation (%) 8 11 8 9 8 11 10 9 7 10 5 25 12 3 3 10 11 3 11 Flammability UL94 / 0.3mmt V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-2 V-0 V-2 V-0 V-0 V-0 V-0 UL94 / 0.8mmt V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-2 V-0 V-2 V-2 V-2 V-2 V-2 UL94 / 1.6mmt V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-2 V-0 V-2 V-2 V-2 V-2 V-2 UL94 / 3.0mmt V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-2 V-0 V-2 V-2 V-2 V-2 V-2 Exudative Is there any surface precipitation after repeated water absorption? without without without without without without without without without without without without without have without without without without without Thermochromic Color difference after heat treatment at 120℃ for 8 hours (⊿E) 10 11 9 10 10 12 12 11 10 13 13 12 12 9 13 11 13 10 18 Formability Demolding resistance value (MPa) 0.5 0.7 0.3 0.5 0.5 0.9 0.8 0.6 0.3 0.7 0.7 0.4 0.8 0.8 1.2 0.4 0.6 0.3 1.1

Examples 1-12 have tensile strengths comparable to those of typical polyamide 6 and 66 resins, and tensile elongation exceeding 5%. Even beyond the tensile yield point, there is no cracking or significant embrittlement, resulting in the expected excellent snap-fit connection. Examples 1-12 achieve a UL94 V-0 rating for flame retardancy at thicknesses of 0.4, 0.8, 1.6, and 3.0 mm, demonstrating high flame retardancy over a wide range of thicknesses. Regarding thermal discoloration, Examples 1-12 exhibit a ΔE of less than 20 after 8 hours at 120°C, indicating that discoloration in hot environments is suppressed. Regarding moldability, the molded product exhibits a resistance value of less than 1 MPa during demolding, making it a composition that is highly unlikely to deform or stick during demolding, even during continuous molding.

On the other hand, while Comparative Examples 1-7 meet some of the requirements, Example 1's flame retardancy at thicknesses of 0.4, 0.8, 1.6, and 3.0 mm is rated UL94 V-2, significantly reducing its flame retardancy and making it unsatisfactory. Comparative Example 2 has a tensile elongation of 3%, failing to suppress embrittlement and making it unsatisfactory. Comparative Example 3 has a flame retardancy rating of V-2 at thicknesses of 0.4, 0.8, 1.6, and 3.0 mm, and a tensile elongation of 3%, making it difficult to say that it combines sufficient flame retardancy with snap-fit properties and is unsatisfactory. Comparative Examples 4, 5, and 7 have a flame retardancy rating of UL94 V-2 at thicknesses of 0.8, 1.6, and 3.0 mm, making it difficult to say that they have high flame retardancy across a wide range of thicknesses and therefore unsatisfactory. Furthermore, the mold release resistance value of Comparative Example 7, an indicator of moldability, exceeds 1 MPa, which cannot be considered good moldability (good mold release properties), and is therefore not ideal. Finally, the flame retardancy of Comparative Example 6 at thicknesses of 0.8, 1.6, and 3.0 mm is rated UL94 V-2. Furthermore, the tensile elongation is only 3%, making it difficult to say that it has sufficient flame retardancy and snap-fit properties, and is not ideal. [Industrial Applicability]

The flame-retardant polyamide resin composition of the present invention is suitable for molded products with a wide range of thicknesses and having a hub. Because the resulting molded products exhibit high flame retardancy across a wide range of thicknesses and excellent snap-fit properties, they are suitable for use in electrical and electronic components, automotive parts, and other applications requiring both high flame retardancy and snap-fit properties.

Claims (4)

A flame-retardant polyamide resin composition comprises a polyamide resin (A) and melamine cyanurate (B). The composition comprises, relative to 100 parts by weight of the combined components (A) and (B), 92-96 parts by weight of the polyamide resin (A), 4-8 parts by weight of the melamine cyanurate (B), 0.01-1 parts by weight of a phosphorus-based antioxidant (C), 0.01-1 parts by weight of a hindered phenol-based antioxidant (D), and 0.1-1 parts by weight of a metal salt-based lubricant containing a fatty acid having 22 or fewer carbon atoms (E). The polyamide resin (A) comprises 55-85 parts by weight of a polyamide 66 resin (A1) and 15-45 parts by weight of a polyamide 6 resin (A2). The flame-retardant polyamide resin composition of claim 1, wherein the fatty acid metal salt lubricant (E) is a metal salt of stearic acid. A molded article is composed of the flame-retardant polyamide resin composition according to any one of claims 1 to 2. The molded article of claim 3, wherein the molded article is any one of a ferrite core cover, an SC gate, a cable tie, and an electrical wiring protection component.