JP7505411B2 - Flame-retardant polyamide resin composition with excellent impact resistance - Google Patents

Description

The present invention relates to a non-halogen flame-retardant polyamide resin composition. More specifically, the present invention relates to a non-halogen flame-retardant polyamide resin composition that has high flame retardancy and good appearance properties, and is capable of producing molded products with excellent impact resistance.

Traditionally, halogen-based flame retardants such as chlorine and bromine have been used to make polyamide resins flame retardant, but these have the problem of generating toxic halogen gases during combustion and corroding processing machinery such as mixers and molding machines during processing.

On the other hand, triazine compounds such as melamine and melamine cyanurate have been used as non-halogen flame retardants for polyamide resins (Patent Documents 1 and 2). However, these triazine compounds have a low flame retardant effect, and it is necessary to add a large amount of triazine compounds to impart high flame retardancy to polyamide resins. In addition, flame retardants using these triazine compounds are flame retardants that are difficult to suppress dripping. In addition, molded products made of flame-retardant polyamide resin compositions containing triazine compounds have the problem that after a long time, the flame retardants such as melamine bleed onto the surface of the molded product, causing the surface of the molded product to turn white. In addition, there is a drawback in that the inherent toughness of polyamide resins is lost.

As a non-halogen flame retardant, red phosphorus is effective as a flame retardant for polyamide resins, and can make polyamide resins flame retardant with a smaller amount than non-halogen flame retardants such as triazine compounds (Patent Document 3). However, red phosphorus can cause fire accidents due to friction during kneading with polyamide resin compositions. In addition, red phosphorus is difficult to pulverize into fine particles due to its characteristics, and has a relatively large particle size distribution, which greatly reduces its physical properties and impairs the toughness that polyamide resins inherently possess.
In addition, when red phosphorus is used, the color of the molded product turns reddish brown unless a pigment is added, which makes it difficult to color the product.

In recent years, composite flame retardants containing phosphorus have been said to be extremely effective in making polyamide resins and the like flame-retardant (Patent Documents 4, 5, and 6). For example, there is a composite flame retardant that combines a phosphinate salt and a metal phosphite salt. These composite flame retardants can be mixed in relatively small amounts with respect to the polyamide resin, and yet provide a high level of flame retardancy. In addition, because the amount of flame retardant mixed is relatively small, the physical properties are said to be good. However, flame-retardant polyamide resin compositions using these composite flame retardants have the disadvantage of impaired impact resistance compared to non-flame retardant polyamide resin compositions, and further improvements are required.

Japanese Patent Publication No. 54-2666 Japanese Patent Publication No. 58-35541 Japanese Patent Application Laid-Open No. 63-243158 JP 2000-219772 A JP 2001-72978 A Patent No. 3044209

The present invention provides a non-halogen flame-retardant polyamide resin composition that has high flame retardancy, good appearance characteristics, and can produce molded products with excellent impact resistance.

As a result of intensive research by the inventors to solve the above problems, they discovered that it is possible to achieve both improved flame retardancy and improved impact resistance by combining a flame retardant combination (comprising a metal salt of phosphinic acid and a metal salt or double salt containing a phosphorous acid component and a specific metal component) with a polyamide resin, a salt of piperazine and an inorganic phosphorus compound, and/or a salt of melamine and an inorganic phosphorus compound, and further blending in a thermoplastic elastomer, thereby completing the present invention.

That is, the present invention is as follows.
[1] A flame-retardant polyamide resin composition comprising 25 to 60 parts by mass of a crystalline polyamide resin (A), 0 to 10 parts by mass of a non-crystalline polyamide resin (B), 0.1 to 10 parts by mass of a thermoplastic elastomer (C), 0.1 to 5 parts by mass of a salt of an inorganic phosphorus compound (D), 5 to 20 parts by mass of a flame retardant combination (E), and 30 to 65 parts by mass of a reinforcing material (F), the total of (A) to (F) being 100 parts by mass, the salt of an inorganic phosphorus compound (D) being a salt of piperazine and an inorganic phosphorus compound, and/or a salt of melamine and an inorganic phosphorus compound, and the flame retardant combination (E) being composed of a metal salt of phosphinic acid (E1) and a metal salt or double salt (E2) containing a phosphorous acid component and one or more metal components selected from the group consisting of alkaline earth metals, transition metals, and aluminum.
[2] The flame-retardant polyamide resin composition according to [1], wherein the crystalline polyamide resin (A) is at least one of polyamide 6 and polyamide 66.
[3] The flame-retardant polyamide resin composition according to [1] or [2], wherein the amorphous polyamide resin (B) is a hexamethylene terephthalamide/hexamethylene isophthalamide copolymer.
[4] The flame-retardant polyamide resin composition according to any one of [1] to [3], wherein the thermoplastic elastomer (C) is a styrene-based thermoplastic elastomer.
[5] The flame-retardant polyamide resin composition according to any one of [1] to [4], wherein the thermoplastic elastomer (C) is a thermoplastic elastomer having a functional group reactive with a polyamide resin.

According to the present invention, by using a specific combination of non-halogen flame retardants in combination with a thermoplastic elastomer, it is possible to produce a polyamide resin composition that combines impact resistance with high flame retardancy (achieving V-0 in the UL94 flame retardancy standard for 1/32 inch thickness).

The present invention will be specifically described below.
The content (blending amount) of each component in the polyamide resin composition of the present invention is expressed as the amount when the total of the crystalline polyamide resin (A), the non-crystalline polyamide resin (B), the thermoplastic elastomer (C), the salt of an inorganic phosphorus compound (D), the flame retardant combination (E), and the reinforcing material (F) is taken as 100 parts by mass, unless otherwise specified.

In the polyamide resin composition of the present invention, the crystalline polyamide resin (A) is an essential component, and the amorphous polyamide resin (B) is an optional component.
The crystalline polyamide resin (A) in the present invention is a crystalline polyamide resin having an endothermic peak due to the melting of crystals in a differential scanning calorimeter (DSC) measurement among polyamide resins having an amide bond (-CONH-) in the molecule. It is a polyamide resin having a clear melting point peak when measured by DSC at a temperature rise rate of 20°C/min according to JIS K 7121:2012. Specifically, it is possible to exemplify polymers such as polyamide 3, polyamide 4, polyamide 5, polyamide 6, polyamide 7, polyamide 8, polyamide 66, polyamide 46, polyamide 6T, polyamide 6I, polyamide MXD6, or crystalline copolymers containing these as components, or blends thereof, but is not limited thereto. In the present invention, polyamide 6 and polyamide 66 are particularly preferred.

The number average molecular weight of these crystalline polyamide resins (A) is preferably 7,000 to 30,000. A number average molecular weight in this range ensures satisfactory toughness and fluidity as a polyamide resin, which is preferable for the present invention.

The content of crystalline polyamide resin (A) is 25 to 60 parts by mass, preferably 25 to 50 parts by mass, and more preferably 27 to 45 parts by mass. By having the content of crystalline polyamide resin (A) within this range, it is possible to achieve the objective of obtaining a polyamide resin composition that has high flame retardancy, good molding flowability and appearance properties, and is capable of producing molded products with excellent impact resistance.

In order to improve the appearance of a molded article obtained from the polyamide resin composition of the present invention, it is preferable to compound (contain) a non-crystalline polyamide resin (B).
The amorphous polyamide resin (B) in the present invention is a polyamide that does not show a clear melting point or a polyamide that shows an exothermic peak during heating when measured by DSC at a heating rate of 20°C/min in accordance with JIS K 7121:2012. Specific examples include polymers, copolymers, or blends obtained by polycondensation of diamines such as 4,4'-diamino-3,3'-dimethyldicyclohexylmethane (CA), 4,4'-diaminodicyclohexylmethane (PACM), metaxylylenediamine (MXD), trimethylhexamethylenediamine (TMD), isophoronediamine (IA), 4,4'-diaminodicyclohexylpropane (PACP), and hexamethylenediamine, and dicarboxylic acids such as terphthalic acid, isophthalic acid, adipic acid, sebacic acid, and dodecanedicarboxylic acid, and lactams such as caprolactam and lauryllactam, but are not limited to these.

Among these amorphous polyamide resins (B), preferred are hexamethylene terephthalamide/hexamethylene isophthalamide copolymer (polyamide 6T/6I), 4,4'-diamino-3,3'-dimethyldicyclohexylmethane (CA)/isophthalic acid (I)/lauryllactam (LL) copolymer (polyamide I/CA/LL), and terephthalic acid (T)/trimethylhexamethylenediamine (TMD) polymer (polyamide T/TMD). Particularly preferred is hexamethylene terephthalamide/hexamethylene isophthalamide copolymer.

The relative viscosity (96% sulfuric acid method) of the amorphous polyamide resin (B) is not particularly limited, but is preferably in the range of 1.8 to 3.5, and particularly preferably in the range of 2.0 to 2.8.
The number average molecular weight of the amorphous polyamide resin (B) is preferably 5,000 to 30,000.

The content of amorphous polyamide resin (B) is 0 to 10 parts by mass, preferably 0 to 8 parts by mass. If it is contained in an amount exceeding 10 parts by mass, no further effect of improving the appearance can be expected. When amorphous polyamide resin (B) is contained, 1 to 10 parts by mass is preferred, 1 to 8 parts by mass is more preferred, and 1 to 6 parts by mass is even more preferred.

The thermoplastic elastomer (C) in the present invention includes styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, polyester-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, etc.

Examples of styrene-based thermoplastic elastomers include, but are not limited to, styrene/butadiene/styrene block copolymer (SBS) and its hydrogenated product, styrene/ethylene-butylene/styrene block copolymer (SEBS), styrene/butadiene copolymer (SBR) and its hydrogenated product, styrene/ethylene/butylene copolymer (HSBR), styrene/isoprene/styrene block copolymer (SIS) and its hydrogenated product, styrene/ethylene-propylene/styrene block copolymer (SEPS).

Examples of olefin-based thermoplastic elastomers include, but are not limited to, rubbers such as ethylene/propylene/diene rubber (EPDM), ethylene/propylene rubber (EPR), butyl rubber (IIR), dynamically crosslinked olefin-based thermoplastic elastomers, and flexible ethylene-based copolymers.

Polyamide-based thermoplastic elastomers include polyetheramides and polyesteramides, which have crystalline polyamides with high melting temperatures as hard segments and polyethers or polyesters with low glass transition temperatures as soft segments.

Polyester-based thermoplastic elastomers are block copolymers of polyether polyester or polyester polyester, with crystalline polyesters with high melting temperatures as hard segments and polyethers or polyesters with low glass transition temperatures as soft segments.

Polyurethane-based thermoplastic elastomers include polyether polyurethane and polyester polyurethane, which have crystalline polyurethane with a high melting temperature as the hard segment and polyether or polyester with a low glass transition temperature as the soft segment.

Among these thermoplastic elastomers, styrene-based thermoplastic elastomers are preferred because their flame retardancy is less likely to decrease, and SEBS is particularly preferred.

In the present invention, the thermoplastic elastomer (C) is preferably a thermoplastic elastomer (C) having a functional group that reacts with a polyamide resin, in that impact resistance is further improved. The functional group that can react with a polyamide resin is a group that can react with any of the amino group, carboxyl group, and amide group of the main chain, which are the terminal groups of the polyamide resin, and specific examples thereof include a carboxylic acid group, an acid anhydride group, an epoxy group, an oxazoline group, an amino group, and an isocyanate group.

The content of these functional groups is preferably 0.05 to 8% by mass, more preferably 0.1 to 5% by mass, relative to the thermoplastic elastomer. There are no particular limitations on the method for producing a thermoplastic elastomer having these functional groups, but examples include a method in which a compound having the above-mentioned functional groups is reacted in the process of producing the thermoplastic elastomer, and a method in which pellets of a thermoplastic elastomer and a compound having a functional group are mixed and kneaded in an extruder or the like to cause the reaction.

The content of thermoplastic elastomer (C) in the present invention is 0.1 to 10 parts by mass, preferably 0.1 to 5 parts by mass, and more preferably 0.3 to 4 parts by mass. If the content is more than 10 parts by mass, the flame retardancy of the polyamide resin composition decreases, and it becomes necessary to increase the amount of the flame retardant combination, which is not preferable. Furthermore, if the content is less than 0.1 parts by mass, the impact resistance of the polyamide resin composition does not improve, which is also not preferable.

The thermoplastic elastomer (C) in the present invention may be a flame-retardant thermoplastic elastomer that already contains a salt of an inorganic phosphorus compound (D) as a flame retardant, which is a salt of piperazine and an inorganic phosphorus compound and/or a salt of melamine and an inorganic phosphorus compound as described below.

One of the flame retardants in the present invention is a salt of an inorganic phosphorus compound (D), which is a salt of piperazine and an inorganic phosphorus compound, and/or a salt of melamine and an inorganic phosphorus compound. The salt of piperazine and an inorganic phosphorus compound is selected from piperazine phosphate, piperazine pyrophosphate, and piperazine polyphosphate, which may be used alone or in a mixture. Specific examples of the salt of piperazine and an inorganic phosphorus compound used in the present invention include piperazine orthophosphate, piperazine pyrophosphate, and piperazine polyphosphate. However, in the case of piperazine polyphosphate, the phosphoric acid may be a salt obtained from polyphosphoric acid consisting of a mixture of orthophosphoric acid, pyrophosphoric acid, tripolyphosphoric acid, and other polyphosphoric acids, and piperazine, and the composition of the raw material polyphosphoric acid is not particularly limited.

The composition ratio of the above piperazine and inorganic phosphorus compound is not particularly limited as long as it is within the range in which the flame retardant effect is exhibited, and preferably, the molar ratio of the nitrogen atoms of the piperazine to the phosphorus atoms of the inorganic phosphorus compound is 1:5 to 5:1, and particularly preferably 1:2 to 2:1.

The above-mentioned salts of piperazine and inorganic phosphorus compounds, for example piperazine pyrophosphate salt, can be easily obtained as poorly water-soluble precipitates by reacting piperazine with pyrophosphoric acid in water or an aqueous methanol solution.

The salt of melamine and an inorganic phosphorus compound is selected from melamine phosphate, melamine pyrophosphate, and melamine polyphosphate, which may be used alone or in a mixture. Specific examples of melamine phosphate compounds preferably used in the present invention include, for example, melamine orthophosphate, melamine pyrophosphate, and melamine polyphosphate.

The composition ratio of the above melamine and inorganic phosphorus compound is not particularly limited as long as it is within the range in which the flame retardant effect is exhibited, and preferably, the molar ratio of the nitrogen atoms of the melamine to the phosphorus atoms of the inorganic phosphorus compound is 1:5 to 5:1, and particularly preferably 1:3 to 3:1.

For example, in the case of melamine pyrophosphate, a salt of phosphoric acid and melamine is obtained by reacting sodium pyrophosphate and melamine in any reaction ratio with hydrochloric acid, and then neutralizing with sodium hydroxide to obtain melamine pyrophosphate.

The content of the salt of the inorganic phosphorus compound (D) is 0.1 to 5 parts by mass, preferably 0.1 to 3 parts by mass, and more preferably 0.2 to 3 parts by mass. If the content is less than 0.1 parts by mass, a sufficient flame retardant effect cannot be obtained, and if it is contained in excess of 5 parts by mass, a large amount of gas is generated during extrusion when the resin composition is produced, which may result in unstable operability.

Although the details of the effect of adding the salt of an inorganic phosphorus compound (D) are unknown, it is believed that the compound suppresses the decrease in strength of the polyamide resin caused by the flame retardant combination (E) below, and also suppresses the flammability of the thermoplastic elastomer (C).

The other flame retardant in the present invention, the flame retardant combination (E), comprises a metal salt of phosphinic acid (E1) and a metal salt or double salt (E2) containing a phosphorous acid component and one or more metal components selected from the group consisting of alkaline earth metals (Mg, Ca, Sr, Ba), transition metals (Ti, Mn, Fe, Ni, Cu, Zr, Zn, Mo, Pb, W, etc.), and aluminum.

The metal salt of phosphinic acid (E1) is blended to impart flame retardancy to a molded article formed from the polyamide resin composition of the present invention, and examples thereof include phosphinic acid salts and/or diphosphinic acid salts and/or polymers thereof. Specific examples include aluminum salts, calcium salts, and zinc salts of methylethylphosphinic acid, aluminum salts, calcium salts, and zinc salts of diethylphosphinic acid, and aluminum salts, calcium salts, and zinc salts of methylpropylphosphinic acid. Aluminum salts are particularly preferred from the viewpoint of stability.

The term "phosphinates" encompasses phosphinates and diphosphinates and their polymers. The phosphinates are prepared in aqueous media and are essentially monomeric compounds. Depending on the reaction conditions, polymeric phosphinates may also form under certain circumstances.
Phosphinic acids suitable as a component of the phosphinic acid salt are, for example, dimethylphosphinic acid, ethylmethylphosphinic acid, diethylphosphinic acid, methyl-n-propylenephosphinic acid, methane-1,2-di(methylphosphinic acid), benzene-1,4-(dimethylphosphinic acid) methylphenylphosphinic acid and diphenylphosphinic acid.

The phosphinate salts of the present invention can be prepared by known methods. For example, phosphinic acid is reacted with a metal carbonate, metal hydroxide, or metal oxide in an aqueous solution.

Metal salts or double salts (E2) containing a phosphorous acid component and one or more metal components selected from the group consisting of alkaline earth metals, transition metals, and aluminum are blended in combination with the above (E-1) to achieve high flame retardancy. Metal salts mainly composed of aluminum phosphite are particularly preferred in terms of stability and the effects of the present invention. The aluminum phosphite may be foamable. The metal phosphite salts or double salts listed here are examples and are not limited to these.

The blending ratio of the above-mentioned (E1) and (E2) in the flame retardant combination (E) of the present invention can be varied within a wide range, but it is preferable that the blending ratio of the above-mentioned (E1) component is 50 to 90 mass% and the blending ratio of the above-mentioned (E2) component is 10 to 50 mass% relative to the entire flame retardant combination, and more preferably, (E1) is 60 to 85 mass% and (E2) is 15 to 40 mass%.

The content of the flame retardant combination (E) in the present invention varies greatly depending on the composition of the flame-retardant polyamide resin composition and the targeted flame retardant properties, but is generally 5 to 20 parts by mass. It is preferably 10 to 20 parts by mass, and more preferably 10 to 18 parts by mass. If it is less than 5 parts by mass, the targeted high level of flame retardancy cannot be obtained. If it is more than 20 parts by mass, the physical properties decrease, which is problematic, and it is also economically undesirable.

The reinforcing material (F) in the present invention may be glass fiber, carbon fiber, metal fiber, aramid fiber, asbestos, potassium titanate whisker, wollastonite, glass flakes, glass beads, talc, mica, clay, calcium carbonate, barium sulfate, titanium oxide, and aluminum oxide, among which chopped strand type glass fiber is preferably used.

The amount (content) of the reinforcing material (F) is 30 to 65 parts by mass, preferably 30 to 60 parts by mass, and more preferably 40 to 60 parts by mass, relative to the total polyamide resin composition.

In addition to the above-mentioned components (A), (B), (C), (D), (E), and (F), the impact-resistant flame-retardant polyamide composition of the present invention may contain, as weather resistance improvers used in ordinary polyamide resin compositions, carbon black, copper oxides, and/or alkali metal halides, as light or heat stabilizers, phenolic antioxidants, phosphorus-based antioxidants, release agents, crystal nucleating agents, lubricants, antistatic agents, pigments, dyes, coupling agents, etc. The flame-retardant polyamide composition of the present invention preferably contains the above-mentioned components (A), (B), (C), (D), (E), and (F) in total at 90% by mass or more, and more preferably 95% by mass or more.

The method for producing the flame-retardant polyamide resin composition of the present invention is not particularly limited, and a general single-screw extruder, twin-screw extruder, pressure kneader, etc. can be used as a kneading device, but in the present invention, a twin-screw extruder is particularly preferred.
In one embodiment, the components (A), (B), (C), (D), (E), and (F) are mixed with antioxidants, release agents, pigments, etc. depending on the application, and then fed into a twin-screw extruder. By uniformly kneading the mixture using the twin-screw extruder, a polyamide resin composition with excellent toughness and flame retardancy can be produced. The kneading temperature of the twin-screw extruder is preferably 220 to 300°C, and the kneading time is preferably about 2 to 15 minutes.

The polyamide resin composition of the present invention can be molded into molded products that combine high flame retardancy with high impact resistance, and can therefore be used in a wide variety of applications, including electrical and electronic parts, automobile parts, and building materials. Specific applications include circuit breaker and switchgear housings, electrical equipment such as personal computers, electronic device housings, and automotive electrical parts, making it suitable and useful.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples in any way.
The characteristics and physical properties shown in the following examples and comparative examples were measured by the following test methods.

(1) Charpy impact strength: measured in accordance with ISO-179-1.
(2) Flammability: Measured according to UL94 vertical flame test. Test pieces with a thickness of 1/32 inch were used. V-0 indicates the highest flame retardancy.

(3) Appearance evaluation method of molded products;
A flat plate (length and width: 100 x 100 mm) having a thickness of 2 mm was produced using an injection molding machine (Toshiba Machine Co., Ltd., IS80) under the molding conditions described below, and the gloss value of the appearance was measured using a micro-TRI-gloss manufactured by Gardner Co., Ltd. The higher the gloss value, the better the appearance.

(4) Number average molecular weight of polyamide resin 2 mg of each sample was weighed and dissolved in 4 ml of HFIP/sodium trifluoroacetate 10 mM. The solution was filtered through a 0.2 μm membrane filter, and the obtained sample solution was subjected to gel permeation chromatography (GPC) analysis under the following conditions.
Apparatus: TOSOH HLC-8220GPC
Column: TSKgel Super HM-H x 2, TSKgel Super H2000
Flow rate: 0.25 ml/min, concentration: 0.05% by mass, temperature: 40° C., detector: RI
Molecular weight calculations were based on standard polymethyl methacrylate.
Molecular weights were calculated excluding those with molecular weights of 1,000 or less as oligomers.

The raw materials used in the examples and comparative examples are as follows.
Crystalline polyamide resin (A):
Polyamide 66 (Shenmah, EPR24, number average molecular weight 18200, melting point: 265°C)
Polyamide 6 (manufactured by Shuseisha, TP4208, number average molecular weight 19400, melting point: 225° C.)
Amorphous polyamide resin (B):
Polyamide 6T/6I (manufactured by EMS, Grivory G21, number average molecular weight 15100, relative viscosity 2.4, glass transition temperature 120° C.),
Thermoplastic elastomer (C):
Maleic acid modified styrene-ethylene-butylene-styrene block copolymer (modified SEBS) (Asahi Kasei Corporation, Tuftec M-1943)
Styrene-ethylene-butylene-styrene block copolymer (SEBS) (Tuftec H1221, manufactured by Asahi Kasei Corporation)
Salt of inorganic phosphorus compound (D):
Piperazine phosphate (ADEKA Corporation, Adekastab FP-2200S)
Melamine phosphate (ADEKA Corporation, Adeka STAB FP-2200)
Piperazine phosphate-containing elastomer (C)+(D):
The SEBS and the piperazine phosphate were mixed in a mass ratio of 6:4 and kneaded in a twin-screw extruder to produce a composite.
Flame retardant combination (E):
(E-1) metal phosphinate;
Aluminum dimethylphosphinate (EXOLIT OP1230, manufactured by Clariant Japan)
(E-2) metal phosphite;
Aluminum phosphite (TAIHEI CHEMICAL INDUSTRIES CO., LTD. APA-100)
Reinforcement material (F):
Glass fiber (T-275H, manufactured by Nippon Electric Glass Co., Ltd.)

(Examples 1 to 15 (Example 13 is a reference example) , Comparative Examples 1 to 9)
Each pre-dried raw material was weighed in the ratio shown in Tables 1 and 2, and charged into the hopper of a twin-screw extruder. The kneading temperature of the twin-screw extruder was 210-270°C when polyamide 6 was used, and 250-290°C when polyamide 66 was used. The strand extruded from the extruder was quenched and pelletized. The pellets of the flame-retardant polyamide resin composition obtained by drying were molded into samples for evaluating physical properties using an injection molding machine. In the case of polyamide 6, the cylinder temperature of the molding machine was 230-280°C and the mold temperature was 80°C, and in the case of polyamide 66, the cylinder temperature of the molding machine was 270-300°C and the mold temperature was 80°C.
The evaluation results are shown in Tables 1 and 2.

In all of Examples 1 to 15, the Charpy impact strength was 13 KJ/ ^m2 or more and the flame retardancy was V-0, indicating that a non-halogen-based flame-retardant polyamide resin composition having both impact resistance and flame retardancy was obtained.
In Comparative Example 1, since the only flame retardant is the flame retardant combination (E), the flame retardancy is only V-1, and the Charpy impact strength is only 10 KJ/ ^m2 . In Comparative Example 2, the Charpy impact strength is improved to 13 KJ/ ^m2 due to the effect of the modified thermoplastic elastomer (C), but the flame retardancy is V-2. In Comparative Example 4, even if the flame retardant combination (E) is increased, the flame retardancy is only V-2. In Comparative Example 5, the Charpy impact strength is only slightly improved by simply using piperazine phosphate in addition to the flame retardant combination (E). In Comparative Examples 6 and 7, the glass fiber filling amount is 40 mass%, but the impact strength does not improve unless an elastomer is added, and if an elastomer is added, flame retardancy cannot be achieved. This is the same even in Comparative Examples 8 and 9, where the glass fiber filling amount is 60 mass%.

The polyamide resin composition of the present invention is a non-halogen flame-retardant molding material that combines excellent impact resistance with high flame retardancy. It can exhibit high flame retardancy of UL94 V-0 class even at a thickness of 1/32 inch, and is applicable to products in all fields that require flame retardancy, from thin electronic components to thick electrical components. It is an engineering plastic that can be used in a wide range of fields and is expected to make a great contribution to the industrial world.

Claims (5)

A flame-retardant polyamide resin composition comprising 25 to 60 parts by mass of a crystalline polyamide resin (A), 0 to 10 parts by mass of a non-crystalline polyamide resin (B), 0.1 to 10 parts by mass of a thermoplastic elastomer (C), 0.1 to 5 parts by mass of a salt of an inorganic phosphorus compound (D), 5 to 20 parts by mass of a flame retardant combination (E), and 30 to 65 parts by mass of a reinforcing material (F), the total of (A) to (F) being 100 parts by mass, the salt of the inorganic phosphorus compound (D) being a salt of piperazine and an inorganic phosphorus compound, and the flame retardant combination (E) being composed of a metal salt of phosphinic acid (E1) and a metal salt or double salt (E2) containing a phosphorous acid component and one or more metal components selected from the group consisting of alkaline earth metals, transition metals, and aluminum. The flame-retardant polyamide resin composition according to claim 1, wherein the crystalline polyamide resin (A) is at least one of polyamide 6 and polyamide 66. The flame-retardant polyamide resin composition according to claim 1 or 2, wherein the amorphous polyamide resin (B) is a hexamethylene terephthalamide/hexamethylene isophthalamide copolymer. The flame-retardant polyamide resin composition according to any one of claims 1 to 3, wherein the thermoplastic elastomer (C) is a styrene-based thermoplastic elastomer. The flame-retardant polyamide resin composition according to any one of claims 1 to 4, wherein the thermoplastic elastomer (C) is a thermoplastic elastomer having a functional group that reacts with a polyamide resin.