JPH0796645B2 - Polyamide resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a polyamide resin composition. More specifically, the present invention relates to a polyamide resin which is flame-retardant and has excellent heat resistance stability that does not become colored even when heated and dried.

<Prior Art> Polyamide resins are used in various fields such as automobile parts, electric / electronic parts, and mechanical parts due to their good mechanical properties, molding processability, and chemical resistance. There is a strong demand for flame retardancy in electric / electronic component applications, and it is necessary to impart even higher flame retardancy to polyamide resins that are inherently self-extinguishing. Polyamide resins obtained by blending a polyamide resin with a triazine-based compound flame retardant are well known (JP-A-53-31759 and JP-A-53759).
−125459). This polyamide resin is a very excellent resin composition having sufficient flame retardancy and no bleed-out or blooming.

<Problems to be Solved by the Invention> These flame-retardant polyamide resin compositions may also be reused with molding scraps such as sprue and runner generated during molding for the purpose of improving the productization rate during molding and processing. Usually done. For reuse, sprue and runners are crushed by a crusher. Polyamide resin is hygroscopic and absorbs moisture in the air during the grinding operation. If a hygroscopic polyamide resin is used as it is for molding and processing, it will remarkably deteriorate in molding and processing due to foaming due to moisture. So usually 80
Drying is performed at a temperature of ℃ to 150 ℃. Polyamide resins have the disadvantage that they are markedly colored when the drying is carried out in a stream of air. Therefore, a difference in color tone occurs between a product in which the molding / processing waste is reused and a product in which the waste is not reused, and the commercial value is significantly reduced. Therefore, as a result of intensive investigations by the present inventors to obtain a flame-retardant polyamide resin composition which is excellent in heat resistance and is not colored even under dry conditions in high temperature air, a specific inorganic phosphorus compound is added. As a result, they have found that the above-mentioned object can be easily achieved, and have reached the present invention. Flame-retardant polyamide resin compositions containing a phosphorus compound are known. That is, in JP-A-54-94540, organic and inorganic phosphorus compounds are added, in JP-A-58-183747, organic phosphorous acid compounds are added, and in JP-A-51-59946, alkali hypophosphite is added. The addition of metal salts is shown. However, the invention disclosed in the publication does not use a triazine-based flame retardant and a hypophosphorous oxide at all, and the object is to improve the heat resistance of the flame retardant, tensile elongation and impact resistance. Is added as a flame retardant aid for improving the flame retardancy or improving the flame retardancy, and no improvement in coloring is shown. An object of the present invention is to provide a polyamide resin composition which is flame-retardant and which is not colored even when heated and dried in an air atmosphere and has excellent heat stability.

<Means for Solving the Problems> That is, the present invention relates to 100 parts by weight of a polyamide resin, (a) 1 to 20 parts by weight of a melamine / cyanuric acid flame retardant, and (b) an alkaline earth metal hypophosphite. Provided is a polyamide resin composition containing 0.001 to 5 parts by weight of at least one compound selected from the group consisting of sodium hypophosphite, aluminum hypophosphite, potassium hypophosphite and manganese hypophosphite. It is a thing.

The present invention will be described in detail below.

The polyamide resin used in the present invention is a polyamide containing amino acid, lactam or diamine and dicarboxylic acid as main constituents. Specific examples of the constituents are ε
-Lactams such as caprolactam, enanthlactam, ω-laurolactam, amino acids such as ε-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, tetramethylenediamine, hexamethylenediamine, undecamethylenediamine, dodecamethylenediamine , 2,2,4- / 2,4,4-trimethylhexamethylenediamine, 5-methylnonamethylenediamine, m-xylylenediamine, p-xylylenediamine, 1,3-bisaminomethylcyclohexane, 1,4 -Diamines such as bisaminomethylcyclohexane, bis-p-aminocyclohexylmethane, bis-p-aminocyclohexylpropane and isophoronediamine, adipic acid, suberic acid, azelaic acid, sebacic acid, dodecane diacid, 1,4-cyclohexanedicarboxylic acid Acid, 1,3-cyclohex There are dicarboxylic acids such as sandicarboxylic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid and dimer acid. These constituents are subjected to polymerization in the form of a single kind or a mixture of two or more kinds, and any of the polyamide homopolymers and copolymers thus obtained can be used in the present invention. Polyamides particularly useful in the present invention include polycapramide (nylon 6) and polyhexamethylene adipamide (nylon 6).
6), polytetramethylene adipamide (nylon 46),
Polyhexamethylene sebacamide (nylon 610), polyundecane amide (nylon 11), polydodecane amide (nylon 12), polyhexamethylene adipamide / hexamethylene terephthalamide copolymer (nylon 66/6)
T), polycapramide / polyhexamethylene adipamide copolymer (nylon 6/66) and mixtures of these polyamides.

The degree of polymerization of the polyamide used here is not particularly limited, and the relative viscosity of a 1% concentrated sulfuric acid solution at 25 ° C is 1.
Any material within the range of 5 to 5.0 can be used.

The melamine-cyanuric acid (MC salt) flame retardant is an equimolar reaction product of melamine and cyanuric acid, for example, an aqueous solution of melamine and an aqueous solution of cyanuric acid are mixed, and the mixture is heated at 90 ° C to 100 ° C.
It is obtained by reacting at 0 ° C. under stirring and passing through the formed precipitate. This is a white solid, and it is preferable to use it after pulverizing it into a fine powder. Further, some of the amino salt and hydroxyl group in the MC salt may be substituted with other substituents.

Furthermore, as the amount of MC salt flame retardant used, polyamide resin 100
It is usually 1 to 20 parts by weight, and particularly preferably 3 to 15 parts by weight, based on parts by weight. When the amount used is less than 1 part by weight, the effect as a flame retardant is not exerted, and even when the amount used exceeds 20 parts by weight, the flame retardancy obtained is not further improved.

Any known technique can be applied to the method of compounding the MC salt flame retardant into the polyamide resin, but in order to obtain a flame retardant resin that makes the best use of the advantages of the flame retardant used in the present invention, it is difficult to atomize with a polyamide resin. It is preferable to mix the flame retardant with a Henschel mixer or the like and then internally mix with an extruder or the like.

Among the (b) metal hypophosphite salts used in the present invention, examples of the alkaline earth metal hypophosphite include calcium hypophosphite, strontium hypophosphite, barium hypophosphite, and hypophosphite. Examples thereof include beryllium and magnesium hypophosphite. Particularly preferably, calcium hypophosphite, barium hypophosphite and magnesium hypophosphite are used. In addition, sodium hypophosphite, potassium hypophosphite, manganese hypophosphite, and aluminum hypophosphite can be used as the metal hypophosphite salt (b). The addition amount of these metal salts is usually 0.001 to 5 parts by weight, and particularly preferably 0.01 to 3 parts by weight, based on 100 parts by weight of the polyamide resin. If the amount added is less than 0.001 part by weight, the heat resistance stability of the polyamide resin will be significantly reduced, and coloring will occur under dry conditions in an air atmosphere.
Even if the addition amount is more than 5 parts by weight, the heat resistance stability of the obtained polyamide resin is not further improved. The addition time of the alkaline earth metal hypophosphite is not particularly limited, and it can be added at any stage before, during, or after the polymerization. The metal hypophosphite may be used alone or in combination of two or more.

The polyamide resin composition of the present invention may be used as a polyamide resin composition master of a polyamide resin and a metal hypophosphite, a polyamide resin, a triazine-based compound flame retardant and a polyamide resin with a metal hypophosphite. Use as a composition master is also possible and is included in the preferred embodiment of the invention. To the polyamide resin composition of the present invention, other additives such as a lubricant, an antistatic agent, a weathering agent, a heat-resistant agent, a reinforcing agent, etc. are added in an appropriate amount at any stage so long as the effects of the present invention are not significantly impaired. be able to.

<Examples> Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

All "parts" in the examples and comparative examples are "parts by weight".
The color tone “YI value” is a value indicating the degree of yellow coloring measured by SM-Color Computer: SM-3 manufactured by Suga Test Instruments Co., Ltd. The larger the value, the more yellow the color is.

Comparative Example 1 Hexamethylenediamine adipate 1900 g, water 630 g
Was placed in a polymerization kettle and purged with nitrogen, and then polymerization was carried out in accordance with a usual polymerization method. Spinning was performed in a strand from the polymerization kettle and cut with a cutter to obtain pelletized polyamide resin. The pellet was vacuum dried at 80-100 ° C. for 16 hours. To 100 parts by weight of the dried pellets, 5 parts by weight of MC salt was added and mixed by a Henschel mixer, and the mixture was melt-kneaded by a twin-screw extruder of PCM30 manufactured by Ikegai Co., Ltd., and the strand was cooled and pelletized by a pelletizer.

The pellets obtained here were dried under vacuum at 80 ° C to 100 ° C for 16 hours. Put these dried pellets in a petri dish and put them in a gear oven (Tabay MFG Co., Ltd.) that is controlled at 140 ° C assuming the drying conditions for recycling 3
The YI value was taken out at 0 minutes and 60 minutes and measured. The results are shown in Table 1.

Examples 1 to 3 Hexamethylenediamine adipate 1900 g, water 630
The heat resistance stability was evaluated in the same manner as in Comparative Example 1 except that g and manganese hypophosphite were added to the polymerization vessel according to the addition amount shown in Table 1 and polymerized, and the results shown in Table 1 were obtained. Compared to Comparative Example 1, the YI value was remarkably reduced and the heat stability was improved.

Examples 4 to 9 Similar to Comparative Example 1 except that sodium hypophosphite was added according to the addition amount shown in Table 1 in place of manganese hypophosphite of Examples 1 to 3 and placed in a polymerization kettle for polymerization. The heat resistance stability was evaluated by operation, and the results shown in Table 1 were obtained. In each case, the YI value was remarkably reduced and the heat resistance stability was improved.

Examples 10 to 13 Comparative Examples except that the manganese hypophosphite of Examples 1 to 3 was replaced by the metal hypophosphite of Table 2 according to the addition amount described in Table 2 and placed in a polymerization kettle and polymerized. The heat resistance stability was evaluated in the same manner as in 1, and the results shown in Table 2 were obtained. Both are YI
The value was significantly reduced, and the heat resistance stability was improved.

Comparative Examples 2 to 10 Heat stability was performed in the same manner as in Comparative Example 1 except that the inorganic phosphorus compounds and organic phosphorus compounds shown in Table 3 were added instead of the manganese hypophosphite of Examples 1 to 3 and polymerized. Was evaluated and the results shown in Table 3 were obtained. None of them had a heat resistance stability higher than that of the metal hypophosphite.

Comparative Examples 11 to 12 The heat resistance stability was evaluated in the same manner as in Comparative Example 1 except that the type of polyamide resin was changed to 6/66 and 610, and the results in Table 4 were obtained.

Examples 14 to 17 The same heat treatment was performed as in Comparative Example 1 except that the polyamide resin and the types were changed to 6/66 and 610, and the metal hypophosphite shown in Table 4 was added and polymerized. It evaluated and obtained the result shown in Table 4. It can be seen that each of them has a smaller YI value than the comparative example and is excellent in heat resistance stability.

Examples 18 to 20 Using the polyamide resin composition of the examples shown in the column of master polymer in Table 5 and the polyamide resin composition of the metal hypophosphite as the master polymer, the polyamide resin shown in the column of type of polyamide resin ( (Diluting polymer) and MC salt were mixed in a ratio of Table 5 by a Henschel mixer, and this mixture was melt-kneaded by a PCM30 twin-screw extruder manufactured by Ikegai Co., Ltd., and the strand was cooled and pelletized by a pelletizer. The pellets obtained here were subsequently evaluated in the same manner as in Comparative Example 1, and the results shown in Table 5 were obtained. In all cases, a polyamide resin composition having a small YI value and good heat stability was obtained.

<Effects of the Invention> A polyamide resin composition comprising a polyamide resin, a triazine-based compound flame retardant, and a metal hypophosphite as in the present invention has excellent heat resistance stability and is particularly recycled in high-temperature drying in an air atmosphere. It is now possible to obtain a polyamide resin composition having a remarkable effect of suppressing the coloring of the polyamide resin composition.

Claims (1)

[Claims] 1. A polyamide resin containing 100 parts by weight of (a) 1 to 20 parts by weight of a melamine / cyanuric acid flame retardant, and (b) an alkaline earth metal hypophosphite, sodium hypophosphite or hypophosphite. A polyamide resin composition comprising 0.001 to 5 parts by weight of at least one compound selected from aluminum phosphate, potassium hypophosphite and manganese hypophosphite.