JP2000186205A - Polyamide resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyamide resin compsn. which is excellent in moldability (melt retention stability) as well as other properties such as flame retardance and heat resistance, and is suitable as a material for molding electric/electronic products, etc. SOLUTION: This polyamide resin compsn. is formed by incorporating 1-100 pts.wt. of an organohalogen compd. (B) and 0.05-2 pts.wt. of an antioxidant (C) having a 10% thermal wt. loss temp. of 300 deg.C or more in nitrogen, into 100 pts.wt. of a polyamide (A) contg. a dicarboxylic acid unit (a) having 60-100 mol% of terephthalic acid unit, and a diamine unit (b) having 60-100 mol% of 1,9-nonanediamine unit, or 1,9-nonanediamine unit and 2-methyl-1,8- octanediamine unit, at a molar ratio of the 1,9-nonanediamine unit to 2- methyl-1,8-octanediamine unit of 100:0-20:80.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyamide composition which gives excellent moldability (melt retention stability) and is excellent in flame retardancy and heat resistance. The polyamide of the present invention can be suitably used, for example, as a molding material for industrial materials, industrial materials, automobile parts, household goods, and the like.

[0002]

2. Description of the Related Art Aliphatic polyamides such as nylon 6 and nylon 66 have excellent properties such as heat resistance, chemical resistance, rigidity, abrasion resistance, moldability, etc., and are therefore often used as engineering plastics. It has been used for applications. In the electric and electronic fields, high flame retardancy based on the UL-94 standard is required. Therefore, many flame retarding methods using various flame retardants have been proposed and put into practical use. However, these aliphatic polyamides have a large water absorption, and there have been problems such as dimensional changes of molded articles and deterioration of physical properties. In recent years, in the electric and electronic fields where flame retardancy is required, a method called a surface mount method (SMT) has been rapidly penetrating for the purpose of high-density mounting of components and efficiency of a soldering process. Accordingly, conventional resins cannot respond to heat resistance.

On the other hand, recently, semi-aromatic polyamides called 6T-based polyamides, which are mainly composed of polyamides composed of 1,6-hexanediamine and terephthalic acid, have entered the electric and electronic fields where flame retardancy is required. And JP 3
JP-A-239755, JP-A-4-96970 and the like have proposed flame-retarding techniques for semi-aromatic polyamides such as 6T-based polyamides. However, a polyamide composed of terephthalic acid and 1,6-hexanediamine has a melting point near 370 ° C., which is higher than the decomposition temperature of the polymer, so that melt polymerization and melt molding are difficult and are not practical. Therefore, in practice, 30 to 40 mol% of a dicarboxylic acid component such as adipic acid or isophthalic acid or an aliphatic polyamide such as nylon 6 is copolymerized to obtain a practically usable temperature range, that is, 2%.
At present, it is used in a composition whose melting point is lowered to about 80 to 320 ° C. Although copolymerization of such a large amount of the third component (or the fourth component in some cases) is certainly effective in lowering the melting point of the polymer, it is accompanied by a decrease in the crystallization speed and the ultimate crystallinity. As a result, not only physical properties such as rigidity at high temperature, chemical resistance and dimensional stability are reduced, but also productivity is reduced due to extension of the molding cycle. Also, fluctuations in various physical properties such as dimensional stability due to water absorption have been improved to some extent compared to conventional aliphatic polyamides by the introduction of aromatic groups, but have reached the level of substantial problem solving. Not.

[0004]

To solve these problems, Japanese Patent Application Laid-Open No. Hei 7-228775 discloses a flame retardant composition of an aromatic polyamide whose main component is a polyamide comprising 1,9-nonanediamine and terephthalic acid. It is proposed in the gazette. The aromatic polyamide flame retardant composition containing a polyamide composed of 1,9-nonanediamine and terephthalic acid as a main component is excellent in flame retardancy, heat resistance, low water absorption and the like,
There is a problem in the retention stability in applications such as injection molding, which are performed by heating and melting. That is, when the resin stays in the melt during molding, the resin or other additives are deteriorated and the viscosity is lowered, so that drooling (drooling), stringing and the like occur, and there is a disadvantage that a good molded product cannot be obtained.

An object of the present invention is to provide a polyamide resin composition which has excellent moldability (melt retention stability) and excellent flame retardancy and heat resistance.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, a polyamide containing terephthalic acid and 1,9-nonanediamine as main components,
A composition using a specific amount of an organic halogen compound in combination, and finding that a flame-retardant polyamide resin composition excellent in the above performance can be obtained by blending a specific amount of a specific antioxidant, The present invention has been completed.

According to the present invention, the object is to provide a dicarboxylic acid unit (a) containing 60 to 100 mol% of a terephthalic acid unit and a 1,9-nonanediamine unit or 1,1
A 9-nonanediamine unit and a 2-methyl-1,8-octanediamine unit in an amount of 60 to 100 mol%,
And 1,9-nonanediamine unit: 2-methyl-1,8
The molar ratio of octanediamine units is from 100: 0 to 20:
1 to 100 parts by weight of the organic halogen compound (B) and 10% of the weight loss temperature by heating in nitrogen at 330 ° C. or more are based on 100 parts by weight of the polyamide (A) comprising the diamine unit (b) of 80. Antioxidant (C) 0.05
This is achieved by providing a polyamide resin composition containing from 2 to 2 parts by weight. Furthermore, as an antioxidant, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 3,9-bis [2-
{3- (3-tert-butyl-4-hydroxy-5-
Methylphenyl) propionyloxy {-1,1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5.5] andecan, bis (2,4-dicumylphenyl) pentaerythritol diphosphite, Tetrakis [3- (dodecylthio) propionyloxymethyl]
One or more compounds selected from the group consisting of methane are used, and the content of bromine element as an organic halogen compound is 15 to 87% by weight, and 5% heating weight in nitrogen. The use of organic bromine compounds having a reduction temperature of 350 ° C. or higher gives better results. Hereinafter, the present invention will be specifically described.

The polyamide which is a component of the composition of the present invention has a terephthalic acid component of 60 mol% or more, preferably 75 mol%, of the dicarboxylic acid components used.
The content is more preferably 90 mol% or more. If the terephthalic acid component is less than 60 mol%, the heat resistance of the resulting polyamide is undesirably reduced.

Other dicarboxylic acid components other than the terephthalic acid component include malonic acid, dimethylmalonic acid, succinic acid, glutaric acid, adipic acid, 2-methyladipic acid,
Aliphatic dicarboxylic acids such as trimethyladipic acid, pimelic acid, 2,2-dimethylglutaric acid, 3,3-diethylsuccinic acid, azelaic acid, sebacic acid, suberic acid; 1,3-cyclopentanedicarboxylic acid, 1,4 Alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid;
Isophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,
7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,4-phenylenedioxydiacetic acid, 1,3
-Phenylenedioxydiacetic acid, diphenic acid, dibenzoic acid, 4,4-oxydibenzoic acid, diphenylmethane-
4,4-dicarboxylic acid, diphenylsulfone-4,4-
Examples thereof include an aromatic dicarboxylic acid such as dicarboxylic acid and 4,4-biphenyldicarboxylic acid, or an arbitrary mixture thereof. Of these, aromatic dicarboxylic acids are preferably used. Further, polycarboxylic acids such as trimellitic acid, trimesic acid, and pyromellitic acid can be used within a range in which melt molding is possible.

The polyamide which is a constituent component of the composition of the present invention contains 1,9-nonanediamine unit or 1,9-nonanediamine unit and 2-methyl-1,8-octanediamine unit among the diamine components used. Is at least 60 mol%, preferably at least 75 mol%, more preferably at least 90 mol%. When the composition of the diamine component is in this range, the resulting polyamide is excellent in heat resistance, which is preferable.

Further, 1,9-nonanediamine unit: 2
The molar ratio of -methyl-1,8-octanediamine units is 1
00: 0 to 20:80, preferably 100: 0 to
The ratio is 60:40, more preferably 100: 0 to 80:20. 1,9-nonanediamine unit: 2-methyl-1,
When the molar ratio of the 8-octanediamine unit is within this range, the resulting polyamide is excellent in heat resistance, and is therefore preferable.

Other diamine components other than the 1,9-nonanediamine and 2-methyl-1,8-octanediamine components include ethylenediamine, propylenediamine, and the like.
1,4-butanediamine, 1,6-hexanediamine,
1,8-octanediamine, 1,10-decanediamine, 1,12-dodecanediamine, 3-methyl-1,5
-Pentanediamine, 2,2,4-trimethyl-1,6
-Hexanediamine, 2,4,4-trimethyl-1,6
Aliphatic diamines such as -hexanediamine and 5-methyl-1,9-nonanediamine; cyclohexanediamine;
Alicyclic diamines such as methylcyclohexanediamine and isophoronediamine; aromatic compounds such as p-phenylenediamine, m-phenylenediamine, xylenediamine, 4,4-diaminodiphenylmethane, 4,4-diaminodiphenylsulfone, and 4,4-diaminodiphenylether Group diamines or any mixture thereof.

The polyamide, which is a component of the composition of the present invention, is a monofunctional compound in which the terminal group of the molecular chain is reactive with an amino group or a carboxyl group at the terminal of the polyamide, such as a monocarboxylic acid or a monoamine. It may be sealed with a certain terminal sealing agent. By performing terminal capping, a composition having more excellent properties such as melt stability and hot water resistance can be obtained.

The amount of the terminal blocking agent that can be used in producing the polyamide which is a component of the composition of the present invention depends on the reactivity, boiling point, reaction apparatus, reaction conditions and the like of the terminal blocking agent used. Although it varies, it is usually used in the range of 0.1 to 15 mol% based on the total number of moles of dicarboxylic acid and diamine.

The polyamide which is a component of the composition of the present invention can be produced by using any known method for producing a crystalline polyamide. For example, polymerization can be performed by a solution polymerization method or an interfacial polymerization method using acid chloride and diamine as raw materials, a melt polymerization method using dicarboxylic acid and diamine as raw materials, a solid phase polymerization method, a melt extruder polymerization method, or the like. An example of a polyamide polymerization method will be described below.

According to the study of the present inventors, first, a catalyst and, if necessary, a terminal blocking agent are added to a diamine and a dicarboxylic acid all at once, to produce a nylon salt.
Polymerization by heating at a temperature of 0 to 250 ° C.
Intrinsic viscosity [η] at 0 ° C is 0.10 to 0.60 dl
/ G of a prepolymer and then subjected to solid-phase polymerization or polymerization using a melt extruder, whereby the polyamide of the present invention can be easily obtained. When the intrinsic viscosity [η] of the prepolymer is in the range of 0.10 to 0.60 dl / g, a shift in the molar balance between carboxyl groups and amino groups and a decrease in the polymerization rate in the post-polymerization stage are small, and the molecular weight is further reduced. A polyamide having a small distribution and excellent in various performances and moldability can be obtained. When the final stage of the polymerization is carried out by solid phase polymerization, it is preferable to carry out under reduced pressure or under an inert gas flow. It is preferable because coloring and gelation can be effectively suppressed. When the final stage of the polymerization is carried out by a melt extruder, the polymerization temperature is 37
When the temperature is 0 ° C. or lower, the polyamide is hardly decomposed, and a polyamide without deterioration is obtained.

The intrinsic viscosity [η] of the polyamide used in the present invention measured at 30 ° C. in concentrated sulfuric acid is preferably 0.4.
To 3.0 dl / g, more preferably 0.6 to 2.0 dl / g.
0 dl / g, even more preferably 0.8 to 1.8 dl
/ G. When the intrinsic viscosity is less than 0.4 dl / g, mechanical properties may be impaired, and when the intrinsic viscosity is more than 3.0 dl / g, fluidity during molding may be reduced and moldability may be deteriorated.

In producing the above polyamide, as a catalyst, for example, phosphoric acid, phosphorous acid, hypophosphorous acid or a salt thereof or an ester thereof, specifically, potassium, sodium, magnesium, vanadium, calcium, zinc, cobalt Use metal salts such as manganese, tin, tungsten, germanium, titanium, antimony and ammonium salts, ethyl ester, isopropyl ester, butyl ester, hexyl ester, isodecyl ester, octadecyl ester, decyl ester, stearyl ester, phenyl ester, etc. can do.

The composition of the present invention contains an organic halogen compound as a component other than the above polyamide. As the organic halogen compound, specifically, brominated polystyrene, polybrominated styrene, brominated polyphenylene ether, brominated bisphenol type epoxy polymer, brominated styrene maleic anhydride polymer, brominated epoxy resin, brominated Phenoxy resin, decabromodiphenyl ether, decabromobiphenyl, brominated polycarbonate, perchlorocyclopentadecane, brominated cross-linked aromatic polymer, and these organic halogen compounds are one kind,
Alternatively, two or more kinds may be used as a mixture, and brominated polystyrene is particularly preferred. The organic halogen compound preferably has a halogen element content of 15 to 87.
% By weight, more preferably 50 to 70% by weight, and the 5% heating weight loss temperature in nitrogen is preferably 350 ° C. or more. The compounding amount of the organic halogen compound is 1 to 100 parts by weight, preferably 10 to 60 parts by weight, based on 100 parts by weight of the polyamide.

The composition of the present invention contains, as a component other than the polyamide and the organic halogen compound, an antioxidant having a 10% heating weight loss temperature in nitrogen of 330 ° C. or more. Any antioxidant can be used as long as it satisfies the above performance. For example, hindered phenol-based, phosphorus-based, thio-based and various derivatives thereof may be mentioned. These antioxidants may be used alone or in combination of two or more. Pentaerythrityl-tetrakis [3- (3,5-ditalbutyl-4-hydroxyphenyl) propionate], 3,
9-bis [2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy}-
1,1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5.5] andecan and 1,3,5-
Trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, phosphorus-based bis (2,4-dicumylphenyl) pentaerythritol diphosphite, thio-based tetrakis [3 -(Dodecylthio) propionyloxymethyl] methane and the like are preferred. The amount of the antioxidant is 0.05 to 2 parts by weight, preferably 0.1 to 1 part by weight, based on 100 parts by weight of the polyamide. The amount of the antioxidant is 0.
If it is less than 05 parts by weight, the melt retention stability is poor, and a good molded product cannot be obtained. If it exceeds 2 parts by weight, mechanical properties may be impaired, which is not preferable.

[0021] The composition of the present invention may contain a flame retardant aid. Specific examples of the flame retardant aid include antimony trioxide, antimony pentoxide, sodium antimonate, sodium oxide, tin oxide, zinc oxide, iron oxide, magnesium hydroxide, calcium hydroxide, zinc borate, kaolin, and clay. , Calcium carbonate and the like. These flame retardant aids may be treated with a silane coupler, a titanium coupler, or the like, and may be used alone or in combination of two or more. As the flame retardant aid, a mixture of antimony pentoxide and sodium oxide is particularly preferred. Also,
The flame retardant aid is used in an amount of 0 to 100 parts by weight of the polyamide.
50 parts by weight, preferably 1 to 30 parts by weight.

Further, the composition of the present invention may contain a phosphorus compound as a flame retardant in addition to the organic halogen compound. Specific examples of the phosphorus compound include a phosphate, a halogen-containing phosphate, a condensed phosphate, a polyphosphate, and red phosphorus.
These phosphorus compounds may be used alone or in combination of two or more. The amount of the phosphorus compound to be used is preferably 0.1 to 30 parts by weight, more preferably 0.5 to 20 parts by weight, based on 100 parts by weight of the polyamide. By adding the phosphorus compound, effects such as further improvement of the flame retardancy of the composition of the present invention and prevention of thermal coloring can be obtained.

The composition of the present invention may further contain, if necessary, glass fiber, carbon fiber, boron fiber, aramid fiber,
A fibrous reinforcing agent such as a liquid crystal polyester fiber, and a powdery reinforcing agent such as silica, silica alumina, alumina, talc, graphite, titanium dioxide, molybdenum disulfide, and polytetrafluoroethylene can be blended. Among them, glass fiber is preferable from the balance between the reinforcing effect and the moldability. The reinforcing agent is usually added in an amount of 0 to 300 parts by weight with respect to 100 parts by weight of the composition of the present invention.

Further, the composition of the present invention may contain, if necessary, a coloring agent, an ultraviolet absorber, a light stabilizer, an antistatic agent,
Plasticizers, release agents, lubricants, nucleating agents or other polymers can also be added.

Examples of the method of compounding the above-mentioned components include a method of adding at the time of the polycondensation reaction, a method of dry-blending, and a method of melt-kneading and mixing using an extruder. The latter method is advantageous.

The polyamide resin composition of the present invention not only has excellent moldability (melt retention stability), but also has flame retardancy,
It has excellent heat resistance and other properties, and can be suitably used for a wide range of conditions in electrical and electronic parts.

[0027]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto. The intrinsic viscosity, weight loss under heating, flammability and molding stability in the examples were measured by the following methods.

Intrinsic viscosity [η]: in concentrated sulfuric acid at 30 ° C.
Intrinsic viscosities (ηinh) of the samples having concentrations of 0.05, 0.1, 0.2, and 0.4 g / dl were measured, and the extrapolated value to 0 was defined as the intrinsic viscosity [η]. ηinh = [ln (t1 / t0)] / c [wherein, ηinh represents the intrinsic viscosity (dl / g), t0 represents the flow time of the solvent (second), and t1 is the flow time of the sample solution (second). And c is the concentration of the sample in the solution (g / dl)
Represents ]

Heating weight loss: METTLER TA-4000
It was measured by TG / DTA using a thermal analysis system.
Temperature rise rate 10 ° C /
The temperature at which the weight was reduced by 10% when heated in minutes was measured.

Flammability: Performed in accordance with the UL standard shown below. The upper end of the test piece is clamped to fix the test piece vertically, a predetermined flame is applied to the lower end for 10 seconds and then separated, and the burning time (first time) of the test piece is measured. Immediately after the fire was extinguished, the flame was immediately applied to the lower end again and released, and the burning time of the test piece (2
Measurement). Repeat the same measurement for 5 pieces,
A total of ten data, five data of the first burning time and five data of the second burning time, are obtained. The total of the ten data is T, and the maximum value of the ten data is M. T
V is less than 50 seconds, M is less than 10 seconds, it does not burn up to the clamp, and if the melted flame does not fall and ignite the cotton 12 inches below, it is equivalent to V-0, T is 250
It is equivalent to V-1 if the same conditions as those of V-0 are satisfied, and M is not more than 30 seconds and M is 30 seconds or less.

Molding stability (melt retention stability): mold clamping force 4
0 ton injection molding machine (PS40 manufactured by Nissei Plastic Industry Co., Ltd.)
E5ASE, cylinder diameter φ26 mm), 30 shots of an evaluation sample that can be molded at a cylinder temperature of 330 ° C. and a weighing value of 16 mm were formed. It was measured. Good if the amount of drooling is less than 4 g;
○: 4 g or more was bad; The amount of the resin remaining in the cylinder of the molding machine is 14.7 g when calculated from the cylinder diameter (φ26 mm), the measured value (16 mm), and the specific gravity (1.6) of the resin composition.

Examples 1 to 4 Terephthalic acid, 1,9-nonanediamine and 2-methyl-1,8-octanediamine [1,9-nonanediamine: 2-methyl-1,8-octanediamine (molar ratio)
= 85: 15], [η] 1.00 dl / g, melting point 308 ° C polyamide (hereinafter PA9T)
After drying at 20 ° C for 24 hours, glass fiber (Nitto Boseki Co., Ltd.)
CS3J-256S), and brominated polystyrene (Pyrocheck 68PB, manufactured by Ferro Japan Co., Ltd.), and the following antioxidants A to D, and a mixture of sodium oxide and antimony pentoxide (Nissan Chemical Industries, Ltd. ) Was dry-blended in the amount (parts by weight) shown in Table 1. This was fed to a twin-screw extruder (screw diameter 30 mm, L / D = 28, cylinder temperature = 3
The mixture was melt-kneaded at a temperature of 10 to 330 ° C. and the number of rotations = 150 rpm, and pelletized. Various physical property values of the obtained composition were measured. Table 2 shows the obtained results. Antioxidant A: 3,9-bis [2- {3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl] -2,4,8 ,
10-Tetraoxaspiro [5.5] andecan Sumitomo Chemical Co., Ltd. Sumilizer GA-80 Antioxidant B: pentaerythrityl-tetrakis [3-
(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] Irganox 1010 antioxidant C: Teibakis [3- (dodecylthio) propionyloxymethyl] methane manufactured by Ciba Geigy ADK STAB AO-412S manufactured by Asahi Denka Kogyo KK Antioxidant D: bis (2,4-dicumylphenyl) pentaerythritol diphosphite Adekastab PEP-45 manufactured by Asahi Denka Kogyo KK

Comparative Example 1 Example 1 was repeated except that the antioxidant was omitted.
The same formulation as in Example 1 was dry-blended in the amount (parts by weight) shown in Table 1, melt-kneaded and pelletized in the same manner as in Example 1. The results obtained are shown in Table 2 below.

Comparative Examples 2 to 4 In Example 1, the following antioxidants E to
Except for changing to G, the same blend as in Example 1 was dry-blended in the amount (parts by weight) shown in Table 1, melt-kneaded and pelletized in the same manner as in Example 1. The results obtained are shown in Table 2 below. Antioxidant E: bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite Adekastab PEP-36 manufactured by Asahi Denka Kogyo KK Antioxidant F: tetrakis (2,4-di-t) -Butylphenyl) -4,4-biphenylylene diphosphite Sand stub P-EP manufactured by Clariant Japan K.K.
Q Antioxidant G: N, N'-hexamethylenebis (3,5
-Di-t-butyl-4-hydroxyphenyl) propionate Ciba-Geigy Irganox 1098

[0035]

[Table 1]

[0036]

[Table 2]

[0037]

Industrial Applicability The polyamide resin composition of the present invention is excellent in moldability (melt retention stability), flame retardancy, heat resistance, etc., and is suitable for electric / electronic parts and other molding materials. It can be suitably used.

Continuation of the front page (72) Inventor Hideaki Oka 2045, Sazu, Kurashiki-shi, Okayama Prefecture Kuraray Co., Ltd. F-term (reference) 4J002 BC112 CD122 CG032 CH072 CH082 CL031 EB136 ED076 EJ017 EL127 EV077 EW087 FD010 FD077 FD130 FD132 FD136

Claims (3)

[Claims] 1. A terephthalic acid unit having a content of 60 to 100 mol%
The contained dicarboxylic acid unit (a) and 1,9-nonanediamine unit, or 1,9-nonanediamine unit and 2-methyl-1,8-octanediamine unit are 60 to 1
A diamine unit (b) containing 00 mol% units and having a molar ratio of 1,9-nonanediamine unit: 2-methyl-1,8-octanediamine unit of 100: 0 to 20:80.
1 to 100 parts by weight of an organic halogen compound (B) per 100 parts by weight of a polyamide (A) consisting of A polyamide resin composition containing 0.5 to 2 parts by weight. 2. An antioxidant (C) comprising pentaerythrityl-tetrakis [3- (3,5-dital butyl-
4-hydroxyphenyl) propionate], 3,9-
Bis [2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,
1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5.5] andecan, bis (2,4-dicumylphenyl) pentaerythritol diphosphite,
The polyamide resin composition according to claim 1, which is one or more compounds selected from the group consisting of tetrakis [3- (dodecylthio) propionyloxymethyl] methane. 3. An organic bromine compound wherein the organic halogen compound (B) has a bromine element content of 15 to 87% by weight and a 5% heating weight reduction temperature in nitrogen of 350 ° C. or more. Or the polyamide resin composition according to 2 above.