JP2001081316A - Flame retardant polyamide resin composition and its molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a flame retardant polyamide resin composition excellent in discoloration resistance and mechanical properties even in environments of a high-temperature atmosphere and ultraviolet exposure. SOLUTION: This flame retardant polyamide resin composition is obtained by further including an inorganic pigment in an amount of 1-30 pts.wt. based on 100 pts.wt. of a polyamide resin and a phosphorus compound in an amount of 0.0005-0.2 pt.wt. based on 100 pts.wt. of the polyamide resin and expressed in terms of phosphorus element in the flame retardant polyamide resin composition prepared by including a flame retardant in an amount of 1-100 pts.wt. based on 100 pts.wt. of the polyamide resin therein.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame-retardant polyamide resin composition suitable for parts such as lighting fixtures exposed to a severe environment of high temperature atmosphere and exposure to ultraviolet rays.

[0002]

2. Description of the Related Art Polyamide resins have excellent mechanical properties,
Since it has heat resistance, chemical resistance, dimensional stability, flame retardancy, moldability, etc., it is used in a wide range of applications as an engineering resin. In particular, a flame-retardant polyamide resin molded article in which a flame retardant is blended with a polyamide resin is widely used for automobile electric parts and electric / electronic equipment parts due to its excellent flame retardancy. However, the polyamide resin has a problem that it is inferior in discoloration resistance as compared with a general-purpose resin such as polypropylene when used in an environment exposed to ultraviolet rays in outdoor parts or the like, and has been difficult to use so far.

Various techniques for improving the light discoloration resistance of polyamide resins have been proposed so far. For example, JP-A-2
Japanese Patent No. 229853 discloses a power supply component material having improved heat resistance and light resistance by a polyamide resin composition comprising a polyamide resin, an inorganic filler, titanium dioxide, a hindered phenol-based antioxidant, and an organic phosphorus-based stabilizer. A polyamide resin composition has been proposed. In addition, various techniques for improving the heat-resistant discoloration of polyamide resins have been proposed. For example, JP-A-6-157902 proposes a polyamide resin composition having improved heat resistance by a polyamide resin composition comprising a polyamide resin, a copper-based stabilizer, titanium oxide, and an inorganic filler. However, in these proposals, mechanical properties and discoloration resistance under conditions of heat treatment alone or light irradiation alone are improved to some extent, but under a more severe combined environment of high heat and ultraviolet irradiation in applications such as lighting equipment. Cannot be sufficiently satisfied.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a flame-retardant polyamide resin composition having excellent discoloration resistance and mechanical properties even in a high-temperature atmosphere and a severe environment exposed to ultraviolet rays. is there.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a specific polyamide resin composition can achieve the above-mentioned problems, and have reached the present invention. That is, the present invention is as follows. (1) 1 to 1 part by weight of a flame retardant per 100 parts by weight of polyamide
A flame-retardant polyamide resin composition containing 00 parts by weight, further comprising 1 to 30 parts by weight of an inorganic pigment and 0.0005 to 0.2 parts by weight of a phosphorus compound as a phosphorus element. Polyamide resin composition. (2) The polyamide resin composition according to (1), wherein the inorganic pigment is titanium dioxide. (3) The phosphorus compound is a combination of an inorganic phosphorus compound and an organic phosphorus compound (1) or (2).
A polyamide resin composition.

(4) The polyamide resin according to (3), wherein the inorganic phosphorus compound is at least one phosphorus compound selected from hypophosphorous acid, phosphorous acid, phosphoric acid and metal salts thereof. Composition. (5) The polyamide resin composition according to (3), wherein the organic phosphorus compound is a phosphite compound. (6) 1 to 1 part by weight of flame retardant per 100 parts by weight of polyamide
A flame-retardant polyamide resin composition containing 0.0000 parts by weight, further comprising 1 to 30 parts by weight of an inorganic pigment and 0.0005 to 0.2 parts by weight of a phosphorus compound as a phosphorus element. 400 at 120 ° C
A polyamide resin molded article characterized in that the degree of discoloration after irradiation with a Watt mercury lamp for 7 days is ΔE <25.

Hereinafter, the contents of the present invention will be described in detail. The polyamide resin constituting the composition of the present invention may be a known one. For example, various types of polyamides such as a polycondensate of lactam, a polycondensate of a diamine compound and a dicarboxylic acid compound, and a polycondensate of ω-aminocarboxylic acid may be used. For example, nylon 6, nylon 66, nylon 61
0, nylon 6I, nylon 6T, etc., and their copolymerized polyamides such as nylon 66/6, nylon 66/610, nylon 66 / 6I, nylon 66 /
6T, etc., and their mutual blends.

The flame retardant used for the flame-retardant polyamide resin of the present invention includes various types. Representative examples are brominated polystyrene, decabromodiphenyl oxide, halogen-based flame retardants such as perchlorocyclopentadecane, melamine, cyanuric acid, triazine-based flame retardants such as melamine cyanurate, red phosphorus, phosphorus-based materials such as ammonium polyphosphate and the like. Flame retardants, inorganic flame retardants such as antimony oxide, magnesium hydroxide, zinc borate and the like are used. These flame retardants may be used alone or in combination. These flame retardants are usually added in an amount of 1 to 100 parts by weight based on 100 parts by weight of the polyamide resin. Usually, these flame retardants are melt-kneaded with polyamide resin pellets using an extruder to produce flame-retardant polyamide resin pellets.

The inorganic pigments constituting the polyamide resin composition of the present invention include titanium dioxide, carbon black,
Iron oxide, ultramarine and the like can be used. These may be used alone or in combination. Particularly, titanium dioxide is most preferable for use in white resin parts such as lighting equipment. The titanium dioxide used in the present invention is not particularly limited in particle size, and may be either rutile or anatase in crystalline form. Also, Mn,
Compounds such as Al, Zn, and Si may be coated on the titanium oxide surface. These inorganic fillers are added in an amount of 1 to 30 parts by weight based on 100 parts by weight of the polyamide resin. When the amount is less than 1 part by weight, the effect of preventing discoloration in a high-temperature atmosphere and in a more severe environment under ultraviolet irradiation is insufficient, and when the amount is more than 30 parts by weight, there is a concern that mechanical properties are deteriorated.

As the phosphorus compound constituting the composition of the present invention, inorganic and organic phosphorus compounds can be used. As the inorganic phosphorus compound, hypophosphorous acid, phosphorous acid, phosphoric acid, a metal salt thereof, or the like can be used. As the metal species, alkali metals such as sodium and potassium, calcium,
Examples include alkaline earth metals such as magnesium and manganese. These inorganic phosphorus compounds may be used alone,
They may be used together.

Examples of organic phosphorus compounds include bis (2,
6-di-t-butyl-4-methylphenyl) pentaerythritol-di-phosphite (trade name ADK STAB P
EP-36 (hereinafter referred to as PEP-36)), tris (2,4-di-t-butylphenyl) phosphite (trade name IRGAFOS-168), 2-[[2,4,8,
10 Tetrakis (1,1-dimethylethyl) dibenzo [d, f] [1,3,2] dioxaphosphepin-6
-Yl] oxy] -N, N-bis [2-[[2,4,
8,10 tetrakis (1,1-dimethylethyl) dibenzo [d, f] [1,3,2] dioxaphosphepin-
6-yl] oxy] -ethyl] ethanamine (trade name IR
GAFOS-12), distearyl-pentaerythritol-diphosphite (trade name: ADK STAB PEP-
8), bis (2,4-di-t-butylphenyl) pentaerythritol-di-phosphite (trade name: Adekastab PEP-24G), 2,2-methylenebis (4,6-
Phosphite compounds such as di-t-butylphenyl) octyl phosphite (trade name: ADK STAB HP-10), trimethyl phosphite, triethyl phosphite, triphenyl phosphite; tetrakis (2,4-di-t-butylphenyl) ) Phosphonite compounds such as 4,4'-biphenylylene-di-phosphonite (trade name Sandstab P-EPQ), phosphate compounds such as trimethyl phosphate and triethyl phosphate, phenylphosphonic acid, phenylphosphinic acid and the like. Of these, phosphite compounds are preferred. These organic phosphorus compounds may be used alone or in combination.

The amount of the phosphorus compound added is 0.0005 as phosphorus of the phosphorus compound per 100 parts by weight of the polyamide resin.
０．２0.2 parts by weight. When the amount is less than 0.0005 parts by weight, the effect of preventing discoloration in a high temperature atmosphere and under a more severe environment under ultraviolet irradiation is insufficient, and when the amount is more than 0.2 parts by weight, the polyamide compound melts due to the thickening effect of the phosphorus compound. The viscosity may increase, which may hinder molding. More preferably, the inorganic phosphorus compound is 0.0005 as phosphorus.
To 0.05 parts by weight, the organic phosphorus compound is 0.0
It is from 0.1 to 0.1 parts by weight.

The method of adding the inorganic pigment and the phosphorus compound constituting the present invention may be added at any stage of the production of the polyamide, and the method of addition is not limited. For example, a method of adding to a raw material salt aqueous solution of a polyamide, a method of injecting and adding into a molten polyamide in the course of melt polymerization, after blending a polyamide pellet and a powder or a master batch of the additive after finishing polymerization and granulating. Any method such as melt kneading using an extruder or a molding machine may be used.

The flame retardant, inorganic pigment and phosphorus compound of the present invention may be mixed and added simultaneously in desired steps, or may be added in separate steps.
Further, the polyamide composition of the present invention, a glass fiber usually used in polyamide in a range that can achieve the object of the present invention, talc, inorganic fillers such as wollastonite,
Known substances such as a hindered amine-based or hindered phenol-based antioxidant, a heat stabilizer, a sulfur-based antioxidant, a coloring agent, a lubricant and the like can be further contained.

Further, the present invention is a molded article comprising the polyamide resin composition described in detail above. That is,
The molded article of the present invention is based on 100 parts by weight of polyamide.
It comprises a polyamide resin composition containing 1 to 100 parts by weight of a flame retardant, 1 to 30 parts by weight of an inorganic pigment, and 0.0005 to 0.2 parts by weight of a phosphorus compound as a phosphorus element. Examples of molded articles include sockets, switches, cases, covers, etc.
Examples include an injection molded article, an extruded molded article such as a round bar and a pipe, and a blow molded article such as a bottle which are used as electric / electronic parts, automobile interior / exterior parts, automobile electric parts and the like. By molding the molded body using the polyamide resin composition of the present invention, the degree of discoloration in a 7-day exposure test under a 400-watt mercury lamp atmosphere at 120 ° C. can be set to ΔE <25. When ΔE ≧ 25, yellowing coloring is conspicuous, and thus the appearance of the molded article is impaired, and there is a concern that the product value is reduced.

[0016]

EXAMPLES Examples and comparative examples are given below.
The present invention will be described more specifically, but the present invention is not limited by these examples. In addition, the evaluation method is as follows. (1) Method for preparing an evaluation test piece Using a PS40E injection molding machine manufactured by Nissei Plastic Industry Co., Ltd.,
Cylinder temperature 280 ° C, mold temperature 80 ° C, injection pressure 3
A molded article of ASTM-D638 Type 1 was prepared under a molding condition of 0 kg / cm ² gauge pressure and an injection speed of 40%, and this was used as a test piece. (2) Mercury lamp exposure test The test piece was left for 7 days in a mercury lamp exposure tester in which the temperature in the bath was adjusted to 120 ° C. The mercury lamp irradiation tester is provided with a 400 W mercury lamp and a rotating sample table in a tank of a gear oven GPH-200 manufactured by Tabai Espec Co., Ltd.

(3) Discoloration degree A color difference meter ND-300A manufactured by Nippon Denshoku Industries Co., Ltd. was used.
L of each test piece before and after the exposure test
A color difference ΔE as a criterion for judging discoloration resistance by an exposure test was determined from the values, a values, and b values. When the value of ΔE is small, discoloration is small, indicating that the discoloration resistance is more excellent. (4) Tensile strength Using the test piece after the exposure test, ASTM-D638
The tensile strength at break was determined in accordance with. (5) Flame retardant UL94 (Under Writers Labo, USA)
ratifications Inc.). The test piece was prepared using a PS40E molding machine.
One having a thickness of / 16 inch was prepared.

[0018]

Example 1 A 50% by weight aqueous solution of an equimolar salt of adipic acid and hexamethylenediamine (hereinafter referred to as AH salt) 5k
g in a 5 liter autoclave, and sodium hypophosphite monohydrate as an inorganic phosphorus compound becomes 0.01 part by weight (0.003 part by weight of phosphorus element) based on 100 parts by weight of the polymer. The amount was added. After the inside of the autoclave was replaced with nitrogen, the autoclave was heated to 280 ° C., and reacted for 85 minutes while controlling the internal pressure of the autoclave to 18 kg / cm ² to remove water from the reaction system.
The internal pressure was reduced to atmospheric pressure over 60 minutes, allowed to stand for 60 minutes, and then cooled to obtain a nylon 66 resin. The obtained nylon 66 resin is pulverized, and nylon 66
For 100 parts by weight of resin, 7 parts by weight of melamine cyanurate as a flame retardant and 5 parts of titanium dioxide as an inorganic pigment
Parts by weight, blended with 0.31 part by weight (0.03 part by weight of phosphorus element) of PEP-36 as an organic phosphorus compound, and mixed with a twin screw extruder TEM35 manufactured by Toshiba Machine Co., Ltd.
Melt kneading was performed at 90 ° C. to obtain pellets. The obtained pellets were molded using the PS40E, and an exposure test was performed on the obtained test pieces to determine the degree of discoloration and the tensile strength. The obtained pellets were also evaluated for flame retardancy. Table 1 shows the evaluation results.

[0019]

Examples 2 to 4 and Comparative Examples 1 and 2 In the same manner as in Example 1, the types and amounts of the flame retardant, the inorganic pigment, the phosphorus compound and other compounding agents were changed as shown in Table 1. Thus, a polyamide resin composition pellet was obtained. The obtained pellets were evaluated in the same manner as in Example 1. Table 1 shows the evaluation results.

[0020]

[Table 1]

The abbreviations in Table 1 are as follows. PA66: nylon 66 MC: melamine cyanurate Br-PS: brominated polystyrene Sb ₂ O _3: Antimony trioxide TiO _2: Titanium dioxide P1: sodium hypophosphite monohydrate P2: phosphite disodium pentahydrate PEP-36: ADK STAB PEP-36 Irgafos 168 manufactured by Asahi Denka Kogyo KK: IRGAFOS168 GF manufactured by Ciba Geigy Japan KK: Glass fiber (about 10 μm in diameter and about 3 mm in length)

[0022]

The flame-retardant polyamide resin composition of the present invention and the molded article made therefrom have the following remarkable effects because they are constituted as described above in detail. 1. Since the flame-retardant polyamide resin composition according to the present invention has a specific inorganic pigment and a phosphorus compound added thereto, a molded article obtained therefrom can be used over time, even in a severe environment such as a high-temperature atmosphere and under ultraviolet irradiation. The deterioration of mechanical properties and the progress of discoloration with time are extremely small. That is, the heat resistance and light resistance over time are remarkably excellent. 2. Further, since it is a polyamide resin composition to which a specific amount of a phosphorus compound is added, it exhibits a melt viscosity suitable for injection molding and the like, and is excellent in moldability. 3. Accordingly, when the molded article made of the flame-retardant polyamide resin composition of the present invention is used as a part for a lighting fixture or the like which is exposed to high-temperature atmosphere and strong ultraviolet rays for a long period of time, its appearance is remarkable with time. There is no risk that it will be damaged or its value will drop sharply.

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Claims (6)

[Claims] 1. A flame-retardant polyamide resin composition comprising 1 to 100 parts by weight of a flame retardant per 100 parts by weight of a polyamide, further comprising 1 to 30 parts by weight of an inorganic pigment,
A polyamide resin composition comprising 0.0005 to 0.2 parts by weight of a phosphorus compound as a phosphorus element. 2. The polyamide resin composition according to claim 1, wherein the inorganic pigment is titanium dioxide. 3. The polyamide resin composition according to claim 1, wherein the phosphorus compound comprises a combination of an inorganic phosphorus compound and an organic phosphorus compound. 4. An inorganic phosphorus compound comprising: hypophosphorous acid, phosphorous acid,
The polyamide resin composition according to claim 3, wherein the composition is one or more phosphorus compounds selected from phosphoric acid and metal salts thereof. 5. The polyamide resin composition according to claim 3, wherein the organic phosphorus compound is a phosphite compound. 6. A flame-retardant polyamide resin composition containing 1 to 100 parts by weight of a flame retardant per 100 parts by weight of a polyamide, further comprising 1 to 30 parts by weight of an inorganic pigment and a phosphorus compound as a phosphorus element. The polyamide resin composition contained 0.0005 to 0.2 parts by weight and had a discoloration degree of ΔE <2 in a 120-w C atmosphere under irradiation of a 400-watt mercury lamp for 7 days.
5. A polyamide resin molded product, wherein the molded product is composed of: