JPH07278430A - Production of molding of flame-retardant polyamide resin - Google Patents

Abstract

PURPOSE:To provide a production process whereby the foaming and the loss of melt viscosity can be suppressed, the operability in molding is therefore stabilized, and a molding made of a flame retardant polyamide resin and excellent in mechanical properties and flame retardancy can be produced. CONSTITUTION:This production process is to produce a molding of a flame- retardant polyamide resin, wherein 1 pt.wt. polyamide resin composition prepared by melt-mixing 50-90wt.% polyamide of a rerlative viscosity of 3.0 or below with 10-50wt.% melaminecyanurate is mixed with 1-10 pts.wt. polyamide of a relative viscosity of 4.0 or above, and the result and mixture is molded.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a flame-retardant polyamide resin composition. For details, when performing extrusion processing, blow molding, and other molding processes using flame-retardant high-viscosity polyamide, it improves the thermal stability of the resin at high temperatures, and has excellent mechanical properties and flame retardancy. TECHNICAL FIELD The present invention relates to a method for producing a molded polyamide resin product.

[0002]

2. Description of the Related Art As a method of making a polyamide flame-retardant, a method of blending melamine or cyanuric acid as a flame retardant is known (Japanese Patent Publication No. 42-19941 and Japanese Patent Publication No. 47-47).
41745). Although these known flame retardants have a large flame retardant effect, they have drawbacks such as sublimation of the flame retardant during molding to stain the mold and bleed out on the surface of the molded product.

In order to overcome the above drawbacks of melamine and cyanuric acid, it has been proposed to use melamine cyanurate, which is an equimolar mixture of melamine and cyanuric acid (JP-A-53-31759). Melamine cyanurate has some improvement in sublimability, which is a drawback of melamine and cyanuric acid.

Polyamides having a high viscosity, for example a relative viscosity of 4.0 or more, are used in a wide range of fields by molding methods such as extrusion molding and blow molding due to their characteristics of high strength and high toughness.

Attempts have been made for a long time to blend flame retardant polyamide with the above-mentioned melamine cyanurate. However, in this method, when the high-viscosity polyamide is melt-mixed, the resin temperature becomes 270 ° C. or higher due to shearing heat generation, which causes inconveniences such as the generation of gas and a large decrease in the melt viscosity, and the operation failure and molding It had the drawback of causing poor appearance. In addition, the mechanical properties of the molded product were low, and the flame retardant was thermally decomposed, so that the flame retardant performance was insufficient.

[0006]

Therefore, the object of the present invention is to solve the above-mentioned problems of the prior art,
It suppresses the decrease of melt viscosity and stabilizes the operability during molding,
Another object of the present invention is to provide a method for producing a flame-retardant polyamide resin molded product which is excellent in the mechanical performance and flame-retardant performance of the molded product.

[0007]

Means for Solving the Problems The above-mentioned object is, when producing a flame-retardant polyamide resin, 50 to 90% by weight of a polyamide (A) having a relative viscosity of 3.0 or less and 10 to 50% by weight of melamine cyanurate. 1 to 10 parts by weight of a high-viscosity polyamide (B) having a relative viscosity of 4.0 or more is mixed with 1 part by weight of a flame-retardant polyamide composition obtained by melt-mixing the above, and the mixture is subjected to a molding step.

In the present invention, the relative viscosity is 20 ° C.,
Value when 1 g was dissolved in 100 ml of 98% concentrated sulfuric acid (η
r).

The present invention will be described in detail below. As the polyamide used in the present invention, nylon 6 and nylon 1
1, polylactams such as nylon 12, nylon 6
Polyamides obtained by polycondensation of dicarboxylic acids with diamines such as 6, nylon 46, nylon 610, nylon 612, nylon 6/66, nylon 6/12
And the like, and polyamides obtained by kneading two or more of these polyamides.

If the relative viscosity of the polyamide (A) exceeds 3.0, the resin temperature rises due to shearing heat generation during melt kneading with melamine cyanurate, and the reaction between the amide group of polyamide and melamine cyanurate occurs. Foaming occurs and gas is generated. When the relative viscosity exceeds 3.0, it is necessary to set the temperature to 250 ° C. or higher for melt-kneading. This 250 ° C. is the reaction initiation temperature of the amide group of polyamide and melamine cyanurate. Is. By setting the relative viscosity of the polyamide to 3.0 or less, the resin temperature can be set to a temperature not higher than the reaction start temperature or a temperature not significantly exceeding the reaction start temperature during melt kneading with melamine cyanurate.

On the other hand, the relative viscosity of polyamide (B) is 4.
When it is less than 0, the shape stability during molding such as extrusion molding and blow molding is poor, and the mechanical performance is also insufficient.

The melamine cyanurate used in the present invention comprises an aqueous solution of cyanuric acid and an aqueous solution of melamine at about 100.degree.
It is obtained by stirring and reacting at a temperature of 1, the precipitate formed is filtered, and the water content of the filtrate is dried in a drier. Alternatively, a commercially available product can be used as it is or after being crushed.

Polyamide (A) and melamine cyanurate are made into pellet resin by a known kneading method, for example, a twin-screw extrusion kneader. At this time, the cylinder temperature,
The kneading conditions such as the screw rotation speed must be set so that the resin melting temperature does not exceed 250 ° C. or does not significantly exceed 250 ° C. By blending the pellets thus obtained and the polyamide (B) and subjecting them to the molding step, foaming and generation of gas are suppressed, melt viscosity is suppressed, and flame retardancy and mechanical properties are excellent. It is possible to produce a flame-retardant polyamide resin molded product.

In the production of the resin molded product of the present invention, a heat stabilizer used in general engineering plastics,
Well-known additives such as nucleating agents, pigments, dyes, ultraviolet absorbers, antistatic agents, alumina, silica, glass beads, graphite, modifiers such as glass fibers and carbon fibers may be used in combination.

[0015]

EFFECTS OF THE INVENTION According to the method for producing a flame-retardant polyamide resin molded product of the present invention, foaming and gas generation are significantly suppressed in a molding process such as extrusion molding and blow molding of high-viscosity polyamide, and the surface appearance is good. Thus, molded articles having excellent mechanical properties and flame retardancy, for example, various electric, electronic parts, automobile parts and industrial parts can be manufactured.

[0016]

EXAMPLES The present invention will be specifically described below with reference to examples. The part in each example shows a weight part. The tests of foaming, melt viscosity, tensile properties, and flame retardancy were conducted according to the following methods.

1. Foaming test 10mm using an extruder with a screw diameter of 30mmφ
The φ round bar extrusion molding was performed. At that time, the resin temperature is 250
The cylinder temperature was set to be ° C. Further, the residence time was set to 10 minutes, and the average bubble diameter of the obtained round bar cross section was measured.

2. Melt viscosity The melt viscosity was measured by using a melt viscosity measuring device (flow tester, Toyo Seiki), and extruding from a 1 mmφ nozzle after staying at 250 ° C. under a load of 50 kg for 6 minutes.

3. Tensile Properties Tensile strength was measured according to ASTM D638.

4. Flame-retardant The flame-retardant was subjected to a combustion test according to UL94 standard.

Example 1 Nylon 6 having a relative viscosity η r = 2.1 [Kanebo Co., Ltd., Kanebo Nylon MC100] and melamine cyanurate [Chemie Linz Co., trade name melamine cyanurate] are biaxial according to the addition amount shown in Table 1. Extruder [Japan Steel Works, TEX3
0] to obtain master pellets.

[0022]

[Table 1]

The pellets thus obtained were dried under reduced pressure at 80 to 120 ° C. and then dry blended with Nylon 6 (Kanebo Nylon MC160, Kanebo Co., Ltd.) having η r = 6.8 at a ratio shown in Table 1, a foaming test and melting. The viscosity was measured. The dry blended chips were subjected to injection molding to prepare samples for a tensile test and a combustion test, and evaluated for tensile properties and flame retardancy. The results are shown in Table 2.

[0024]

[Table 2]

Examples 2 to 6 As shown in Table 1, nylon 6 (ηr = 2.1 to 2.8)
And melamine cyanurate are mixed using a twin-screw extrusion kneader to obtain master pellets, and then 80 ° C to 120 ° C.
After being dried at 1, the mixture was dry blended with high-viscosity nylon 6 in the ratio shown in Table 1 and subjected to various tests in the same manner as in Example 1.
The results are shown in Table 2.

Comparative Examples 1 to 3 As shown in Table 1, high viscosity nylon 6 and melamine cyanurate were mixed using a twin-screw extrusion kneader to obtain master pellets, which were then dried at 80 to 120 ° C. It was dry-blended with high-viscosity nylon 6 at a ratio shown in Table 1 and subjected to various tests in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 4 Nylon 6 with ηr = 6.8 [Kanebo Co., Ltd., Kanebo Nylon MC160] and melamine cyanurate [Chemie Linz Co., trade name melamine cyanurate] at a weight ratio of 85/15 by twin screw extrusion kneading. Mix using a machine to get pellets,
Then, after drying at 80 to 120 ° C., various tests were performed in the same manner as in Example 1. The results are shown in Table 2.

As can be seen from Table 2, the polyamide resins of Examples 1 to 6 did not generate gas during melt mixing, showed no decrease in melt viscosity, and had good flame retardancy and tensile strength. there were. On the other hand, in Comparative Examples 1, 2, and 4,
The flame retardant was decomposed by heat and was inferior in flame retardancy. Further, in Comparative Examples 1 to 4, gas was generated during melt mixing.

Claims (1)

[Claims] 1. A polyamide (A) 50-9 having a relative viscosity of 3.0 or less in the production of a flame-retardant polyamide resin.
0% by weight and melamine cyanurate 10 to 50% by weight
1 to 10 parts by weight of polyamide (B) having a relative viscosity of 4.0 or more with respect to 1 part by weight of a polyamide resin composition obtained by melt mixing
A method for producing a flame-retardant polyamide resin molded article, which comprises mixing parts by weight and subjecting the mixture to a molding step.