JPS61284407A - Manufacture of polyamide resin composite - Google Patents

Abstract

PURPOSE:To make the mixing of a stabilizing agent with polyamide uniform, by a method wherein water is removed through a vent port of a specific melting and extruding machine by adding the specific stabilizing agent into the polyamide to be melted and kneaded in a form of a water solution. CONSTITUTION:A molten state polyamide resin composite obtained by loading 100wt part polyamide resin and a 0.1-1.0wt part water solution, containing 5-150wt part potassium halide and 0-50wt part copper balide in 100wt part water, into a hopper 3 of a meting and extruding machine 1 provided with a vent hole and mixing up and melting within a cylinder 2 is transferred to a discharge port 6 by a screw 4; as a vent 5 is provided in the midst of the cylinder 2, there surplus water is eliminated out of the molten state polyamide. Therefore, it is desirable to make the inside of the cylinder 2, to which the vent 5 is fitted, into a depressurized atmosphere. Such a degree of subatmospheric pressure as to become the water in the polyamide composite obtainable from the discharge port 6 of an extruding machine into less than 0.2wt% and a passing period of time of its atmosphere are adopted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a polyamide resin composition.

[Conventional technology]

It is already known that copper compounds such as copper halides and potassium halides are effective as stabilizers for conventional polyamides (Japanese Patent Publication No. 57-23962).
.

When adding these stabilizers to polyamide, a method is usually used in which the stabilizers are dispersed in the polyamide using a melt mixer or the like.

[Problem that the invention seeks to solve]

However, in the above method, it is difficult to uniformly disperse these stabilizers, especially potassium halides, in the polyamide.
It is very difficult to do so, and the stabilizer that is not sufficiently dispersed not only causes a decline in physical properties, but also appears as spots on the surface of the product after injection molding, significantly reducing the value of the product.

Therefore, as a method to further improve the dispersibility of the stabilizer,
There is a method described in Kaida No. 59-27949. This method involves mixing polyamide powder with an aqueous solution of potassium iodide and copper iodide, drying the mixture, and then adding the mixture to the polyamide resin, which has been shown to be quite effective.

However, this method requires drying of the polyamide powder, which is actually very difficult and has the problem of poor workability.

An object of the present invention is to provide a method for producing a polyamide resin composition in which a stabilizer is uniformly dispersed.

[Means for solving problems]

That is, the above object of the present invention is to obtain polyamide resin 100
parts by weight and 5 to 1 part by weight of potassium halide in 100 parts by weight of water.
50 parts by weight and 0.1 to 10 parts by weight of an aqueous solution containing 0 to 50 parts by weight of copper halide are supplied to a vented melt extruder and melt-kneaded, and then the water content of the melt-kneaded resin composition is determined. This is achieved by employing a method for producing a polyamide resin composition characterized in that water is removed through a vent hole until the amount of water becomes 0.2% by weight or less.

Hereinafter, the structure of the present invention and the detailed description of the invention will be explained.

The polyamide resin used in the present invention is a known polyamide, such as polycaprolactam, ? Examples include lihexamethyleneazibamide.

As the potassium halide, it is preferable to use potassium iodide;
50, preferably 50 to 120 parts by weight. If it exceeds 150 parts by weight, potassium iodide will precipitate, so it is not good. As the copper halide, it is desirable to use copper iodide, and it is dissolved at a ratio of O to 50, preferably 10 to 40 parts by weight, per 100 parts by weight of an aqueous potassium iodide solution. If it exceeds 50 parts by weight, copper iodide will not be uniformly dispersed in potassium iodide, which is not preferable.

A specific method for adding the above stabilizer to polyamide is as follows:
This is a method of supplying a blend of the aqueous solution and polyamide resin into a vented melt extruder (1) (cylinder mouth) shown in the accompanying drawings.

The blend may be obtained by mixing the polyamide and the aqueous solution in advance, or
(For example) the polyamide resin and the aqueous solution may be continuously metered and supplied into the potper (3), but the latter method is preferred. The molten polyamide resin composition obtained by mixing and dissolving in the cylinder (2) is transferred to the discharge port (6) by the screw (4).
Since a vent (5) is provided in the middle of the cylinder (2), excess water is removed from the molten polyamide there. Therefore, it is desirable to create a reduced pressure atmosphere inside the cylinder to which the vent (5) is attached. The reduced pressure atmosphere is generally created by a known means, for example, a reduced pressure means such as a nutsch pump, and in the present invention, the degree of reduced pressure is preferably -650 txHg/d or less, more preferably -700 mHg/d or less.

Moreover, the water content in the polyamide composition obtained from the discharge port (6) of the extruder is 0.2% by weight or less, preferably 0.2% by weight or less.
The degree of pressure reduction and the passage time of the atmosphere are adopted so that the pressure becomes 1% by weight or less. If the moisture content is more than 0.2% by weight, the polyamide composition will foam, making it difficult to pelletize the strands melt-extruded from the discharge port.

In addition to the above-mentioned stabilizers, the resin composition of the present invention may contain known reinforcing materials such as glass fiber, mica, carbon fiber, pigments,
Dyes, talc, wollastenate, etc. can be added. Hereinafter, the present invention will be explained in detail with reference to Examples.

〔Example〕

Contents common to the Examples and Comparative Examples of the present invention will be explained and explained.

For the preparation of potassium iodide and copper iodide aqueous solutions, see 8.
100 parts by weight of potassium iodide per 100 parts by weight of warm water at 0°C
Part by weight was dissolved, and further 25 parts by weight of copper iodide was dissolved.

Processing after pelletizing is performed using dehumidified air at a temperature of 70°C (dew point -2).
Dry the pellet by exposing it to 0° C. for 5 hours.

The evaluation method is to mold the obtained pellets with a 3-ounce injection molding machine, cut the surface of the molded product, and remove 10 d of the surface.
The evaluation was based on the number of white spots inside. The size of the spots was determined based on the ``Method for Judging Miscellaneous Items'' published by the Ministry of Finance.

Examples 1-3. Comparative Examples 1 and 2 Experiments were conducted under the conditions shown in Table 1, and the results shown in Table 2 were obtained.

Table 2 [Effects of the Invention] In the present invention, a specific stabilizer is added in the form of an aqueous solution to polyamide that is melt-kneaded, and water is removed from the vent of a specific melt extruder. It has the effect of making the mixture evenly mixed inside. Moreover, since the operation is extremely simple, it is an industrially advantageous method.

[Brief explanation of drawings]

The drawing shows a schematic diagram of a vented melt extruder used in the present invention. 1: Melt extruder with vent 2 Niji cylinder 3: Hopper 4: Screw 5: Vent port 6: Discharge port

Claims (1)

[Claims] 100 parts by weight of polyamide resin, 5 to 150 parts by weight of potassium halide and 0 parts by weight of copper halide in 100 parts by weight of water.
0.1 to 1.0 parts by weight of an aqueous solution containing ~50 parts by weight is supplied to a vented melt extruder and melt-kneaded, and then the water content of the melt-kneaded resin composition is 0.2% by weight. A method for producing a polyamide resin composition, characterized in that water is removed through a vent hole until the amount of water is reduced to below.