JPS6043863B2 - Polyamide resin composition for molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polyamide resin composition for molding.

More specifically, the present invention relates to a polyamide resin composition for molding that provides a molded article with a good appearance and has excellent moldability. It is known that when molding polyamide resins, moldability factors such as plasticization stability, fixing speed, and mold releasability greatly contribute to continuous stable molding and cycle shortening.

However, polyamide resins to which no lubricant, crystal nucleating agent, mold release agent, etc. are added generally have extremely poor moldability and cannot be stably molded.

Therefore, during molding, it is essential to add various additives to improve these factors. Therefore, in general, by adding higher fatty acid derivatives such as higher fatty acid metal salts, higher fatty acid amides, higher fatty acid esters, mold release agents and lubricants such as various waxes, and crystal nucleating agents such as metal oxides and metal hydroxides. Improvements in the moldability of polyamide resins have been made. For example, JP-A-52-4254 proposes to improve the moldability of polyamide resin by adding aliphatic carboxylic acids such as calcium stearate and barium stearate or their derivatives together. In this method, the additive used as a mold release agent tends to cause phase separation from the polyamide resin, and especially when mixed onto the chip surface, silver streaks appear on the surface layer of the molded product, resulting in poor appearance. Since it easily occurs, there is a drawback that the amount of addition is limited.

These poor appearance can be improved by extrusion kneading or adding effective additives during polymerization, which tend to cause phase separation with the polyamide resin, but the production cost is high and it is disadvantageous from an industrial perspective. Moreover, it is not preferable because disadvantages such as denaturation of additives and failure to increase the degree of polymerization occur. Therefore, the present inventors have made intensive studies to improve the above-mentioned problems and obtain a polyamide resin composition that provides molded products with good appearance and has excellent moldability. When a group carboxylic acid or its diol ester is added alone to a polyamide resin, a large amount of silver streaks occurs even if the amount added is extremely small, whereas when an aluminum salt of a fatty acid is added to this, a peculiar The inventors have discovered that it is possible to obtain a polyamide resin composition that suppresses the occurrence of silver streaks and has good moldability, and has thus arrived at the present invention. That is, the present invention provides polyamide resin with an aluminum salt of an aliphatic carboxylate having 12 to 20 carbon atoms as a first additive.
．． 1 to 0.5% by weight and as a second additive an aliphatic carboxylic acid having 1 or more carbon atoms or a diol ester thereof 0
．． The object of the present invention is to provide a molding polyamide resin composition containing 1 to 0.3% by weight.

Examples of polyamide resins applicable to the present invention include polycondensates of lactams, polycondensates of diamines and dibasic acids, ω
- Various types of polyamide resins such as polycondensates of amino acids, copolyamides and blends thereof, such as homopolymers such as nylon 6, 66, 610, 11, 12, nylon 6/6, 6/6, etc. 610, 6/1
Examples include copolymers such as 2, 6/6T, and blends thereof.

The first additive contained in the composition of the present invention has 12 to 12 carbon atoms.
Among the 20 aluminum salts of aliphatic carboxylic acids, for example tri-, di- or mono-aluminum salts of aliphatic carboxylic acids such as lauric acid, palmitic acid, stearic acid, oleic acid or mixtures thereof are applied.

Among these, aluminum salts of stearic acid are particularly preferred from the viewpoint of industrial efficiency and effectiveness. The amount added is preferably 0.1 to 0.5% by weight based on the polyamide resin, and at least 50% by weight of the aliphatic carboxylic acid or its diol ester, which is the second additive described below. It is. The second additive contained in the composition of the present invention is an aliphatic carboxylic acid having 22 or more carbon atoms or its dioxycarboxylic acid. Examples of esters include fatty acid carboxylic acids such as behenic acid, lignoceric acid, cerotic acid, montanic acid, melisic acid, etc., or esters obtained from these and aliphatic diols such as ethylene glycol, propylene glycol, and 1◆4-butanediol. There is no problem even if two or more of these additives are used.

In particular, esters of montanic acid with ethylene glycol or 14-butanediol exhibit desirable effects. The amount of this aliphatic carboxylic acid or its diol ester added is 0.1 to 0. If the amount added is 0.1% by weight or less, there is no effect on moldability, and if the amount added is 0.1% by weight or less, there is no effect on moldability. If the amount is more than %, the effect of improving mold releasability is saturated, and further increasing the amount added is not preferable because it only increases the occurrence of silver streaks, which are poor appearance. The composition of the present invention is produced by mixing the above two additives with polyamide resin chips in a well-known manner.

The well-known method refers to a method of mixing on the chip surface using a blender such as a tumbler Henschel mixer. The composition of the present invention may also contain additives in addition to the above two types.

Examples of other additives include heat-resistant agents, weather-resistant agents, flame retardants, and inorganic fillers. The present invention is a polyamide resin composition composed of the above-mentioned composition, which enables continuous and stable production when molded by injection molding or extrusion molding, and particularly provides a good appearance of molded products in injection molding. , the mold release force is small, and the plasticization time is stable, so the molding cycle can be sufficiently shortened.

The present invention will be explained in more detail below using Examples and Comparative Examples. Examples 1 to 3 and Comparative Examples 1 to 8 Nylon 66 chips (shape 2.5 x 2.5 x 2.5?,
JISK-6180 sulfuric acid relative viscosity 3.01 Toray Amilan CM3OOl) or nylon 6 chip (shape 2.
5φ x 2.5wL, sulfuric acid relative viscosity 2.7, Toray Amilan CMlOlO) and various additives shown in Table 1 were mixed for about 3 minutes using a ■-type blender, and molded using a Toshiba Machine 1S-50AM injection molding machine. Injection molding was performed using a mold with a product shape of 215 x 20 x 3 m.

This molded product? Continuously molded 20 shots, this 2C@
The number of silver streaks occurring on the surface layer of molded products was classified according to their size.

To determine the size, we used a measurement chart for miscellaneous objects produced by the Printing Bureau of the Ministry of Finance. That is, the size classification is as follows. Regarding the occurrence of Silver Streaks, if the size is medium or above, it is considered good (denoted as O), and if it is medium in size but not large, it is considered poor (denoted as Δ). Items that are medium, large, and large are defective (displayed as ×)
It was judged as.

Molding conditions are cylinder temperature 280-270-270-25
0C (250-240-240-23 for nylon 6
00C) The mold temperature was 80°C, the injection time was 1 min., and the cooling time was 158 cm.

As a method for evaluating moldability, a vibrator-shaped molded product (35
φ×83e)<2twun) Using a two-cavity mold, the stress when pulling out the molded product from the core was measured as the mold release force.

Judgment: 30 shots molded, 11 to 30 shots, total 20
An average value of the release stress of the shot of 45k9w or less was considered good, a value of 45 to 50k9w was considered to be somewhat poor, and a value of 50k9w or more was considered poor. Regarding plasticization stability, those with stable screw regression were evaluated as good, and those with unstable screw retraction were evaluated as poor.

The molding conditions for this moldability evaluation are cylinder temperature 290-2
80-280-2700C (However, in the case of nylon 6, 2
50-240-240-230℃), mold temperature 80℃,
Injection time: 4 seconds, cooling time: 8 seconds (1 second for nylon 6)
I did it at

These results are shown in Table 1.

Claims (1)

[Claims] 1 0.1 to 0.5% by weight of aliphatic carboxylic acid aluminum salt having 12 to 20 carbon atoms and 0.1 to 0.3% by weight of aliphatic carboxylic acid having 22 or more carbon atoms or its diol ester based on polyamide resin A polyamide resin composition for molding comprising the following: