JPS5835626B2 - Polyamide resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polyamide resin composition with improved moldability.

Specifically, it is a polyamide resin composition that has excellent mold releasability, short plasticization time, and stable moldability, and that also has excellent transparency and can yield molded products with excellent appearance. It is related to.

Polyamide resin is an engineering plastic with excellent performance, and in recent years has been used in a wide range of fields such as electrical parts and mechanical parts.

In these fields, high-speed automatic molding is progressing, and there is an increasing need for products with better mold release properties, shorter plasticization supply times, and less variation.

In addition, although its characteristics are somewhat different from the transparency of non-grade resins such as polystyrene and polycarbonate, the transparency unique to polyamide resin is important in the fields of automobile parts and mechanical parts due to its oil resistance. ing.

Against this background, the mold releasability of polyamide resins is not necessarily satisfactory, and further improvement is desired.

The reason why polyamide resin has poor mold releasability is thought to be that the polyamide resin has strong adhesion to the mold surface, which causes the polyamide resin to adhere to and accumulate on the mold surface.

Further, it is known that the shortening of the plasticization supply time of polyamide resin and its stabilization can be improved by adding fatty acids such as stearic acid and their metal salts such as magnesium stearate.

However, the mold release properties of polyamide resins are hardly improved by the addition of these fatty acids, their metal salts, or waxes such as monoamides and bisamides, and other additives are required to improve the mold release properties. .

The present inventors have recognized that the addition of aliphatic monoamines shown in JP-A No. 47-33139 significantly improves the mold releasability of polyamide resins; It has been found that it not only impairs properties but also causes adverse effects such as destabilizing the plasticization supply time and causing flash marks on the surface of the molded product due to phase separation of the aliphatic monoamine.

In view of this point, the present inventors conducted intensive research and found that by adding aliphatic monoamine and fine particulate anhydrous silica to polyamide resin in combination, they not only improved mold release properties but also shortened the plasticization supply time. Hidden and minimized the variation (
At the same time, the present invention was achieved by successfully obtaining a molded product that does not impair transparency and does not cause flash marks on the surface of the molded product.

That is, the present invention has a polyamide resin of 0.01 to 4
Weight % aliphatic monoamine having 14 to 22 carbon atoms and o, o
This is a polyamide resin composition characterized by containing i~4% by weight of fine particulate anhydrous silica having a specific surface area of 5 mm''/7 or more.

The present invention will be explained in more detail below.

Examples of the polyamide resin used in the present invention include polymers such as ε-caprolactam, aminocaproic acid, enantholactam, η-aminoheptanoic acid, 11-aminoundecanoic acid, 9-aminononanoic acid, a-pyrrolidone, and a-piperidone. , diamines such as hexamethylene diamine, nonamethylene diamine, untecamethylene diamine, dotecamethylene diamine, metaxylylene diamine, and dicarboxylic acids such as terephthalic acid, isophthalic acid, adipic acid, cepatic acid, dodecane dibasic acid, and geltaric acid. Examples include all polyamides such as polymers obtained by polycondensation, copolymers thereof, and mixtures of these polymers or copolymers.

In addition, blends of these polyamides with other polymers such as polyester are also applicable, and depending on the required quality, pigments, dyes, reinforcing agents such as glass fibers and inorganic fillers, and flame retardants are also used. May contain.

The aliphatic monoamine used in the present invention has 14 to 14 carbon atoms.
Limited to 22 saturated and unsaturated aliphatic monoamines.

If an aliphatic monoamine with less than 14 carbon atoms is used, the mold releasability effect will not be sufficient (and aliphatic monoamines with more than 22 carbon atoms are not only difficult to obtain commercially, but also difficult to obtain polyamide molded products that maintain transparency). can't get it.

The amount of aliphatic monoamine used in the present invention is 0.01 to 4% by weight, preferably 0.05 to 4% by weight based on the polyamide resin.
0.5% by weight, most preferably 0.1-0.3% by weight.

If it is less than 0.01% by weight, the desired mold releasability cannot be obtained, and if it is more than 4% by weight, it is not preferable for maintaining transparency.

The fine particulate anhydrous silica used in the present invention is, for example, B
The silicon dioxide has a specific surface area of 50 m'/1 or more as determined by the ET method.

The amount of fine particulate anhydrous silica used in the present invention is 0.01
-4% by weight, preferably 0.05-0.2% by weight.

If it is less than 0.01% by weight, it will have little effect on stabilizing the plasticization supply time or suppressing the occurrence of flash marks, and if it is more than 4% by weight, it will not be possible to maintain transparency, which is undesirable.

Further, if an inorganic substance such as talc or kaolin is added instead of fine particulate anhydrous silica, transparency cannot be maintained.

The composition of the present invention is usually produced by incorporating the above two types of additives into polyamide resin chips after the polymerization reaction has been completed.

Adding the monoamine to the polyamide raw material and polymerizing it,
The method of adding the monoamine to the polyamide during polymerization is not preferred because it lowers the degree of polymerization of the polyamide.

The above two types of additives can be incorporated by kneading a tri-blend of polyamide resin chips and the above two types of additives into pellets using an extruder, or by adding them in high concentration using a similar method. A blend of an appropriate amount of kneaded master pellets and polyamide resin chips is most suitable.

The present invention will be specifically explained below with reference to Examples.
The present invention is not limited in any way by the following examples unless the gist of the invention is exceeded.

In the examples, "%" means "% by weight".

Example 1, Comparative Examples 1 to 6 Nylon 6 (Unitika Nylon A) with a relative viscosity of 2.8 measured in an IP7100CC solution in 98% sulfuric acid at 25°C.
1030, Unitika registered trademark) chips, 0.2% of stearylamine (Fermin 80, manufactured by Kao Soap Co., Ltd.) and 0.05% of fine particulate anhydrous silica (Aerosil 380, manufactured by Nippon Aerosil Co., Ltd.) were stirred and mixed with a V-blender. Homogeneous polyamide resin chips were obtained.

This polyamide resin chip is TS-1 made by Mekkushi Resin Kogyo Co., Ltd.
50 type injection molding machine and length 100mm x width 701nr
/l x height 40mm x average wall thickness 2mm box-shaped molded product 1
Using a square mold, the cylinder temperature was 250°C, the mold temperature was 40 to 60°C, the plasticization supply stroke was 48 mm, the injection pressure was 800 kg/crA, the back pressure was 50 kg/crti, the injection time was IO sec, and the cooling time was 20 sec. Molding was carried out continuously under these conditions and the plasticization supply time was measured with a stopwatch.

In addition, regarding the above conditions, molding is performed by changing only the cooling time from 0 to 100 seconds, and the molded product can be taken out without being deformed at all when ejected with ejector pins (611171Lφ x 4 pieces) after the cooling time. The shortest cooling time (hereinafter referred to as shortest cooling time) was investigated.

Naturally, the shorter the minimum time, the better the mold releasability.

Since the box-shaped product mold described above has a side gate in the center of the opening of the box with a length of 1001n7IL, it is easy to observe flash marks around the gate and phase separation marks in the weld area, making it easy to observe the external appearance. It was observed whether the molded product obtained by the method was beautiful or not.

Next, under the same molding conditions as above except that the mold temperature was 20 to 30°C and the plasticization supply stroke was 20 mm, the size was 90 mm long x 50 mm wide x 3 mrn thick for 2 hours.
Molding was carried out using a stepped plate mold of 1 inch, and the light transmittance at a 17n71L thickness portion of the obtained plate was measured using a haze meter (HAZEMETAR, manufactured by Tokyo Juishoku Co., Ltd.).

The larger the value of light transmittance, the more transparent the material is.

These results are shown in Table 1 below. For comparison, the case of the above-mentioned nylon 6 with no additives (Comparative Example-1) and the case of adding only 0.2% of the above-mentioned stearylamine (Comparative Example-2)
), the results when only 0.1% of the above fine particulate anhydrous silica was added (Comparative Example-3), and the above results when 0.21% of stearylamine and kaolin (manufactured by ENGELHARD,
ASP600) 0.1% (Comparative Example-4)
), when 0.2% of laurylamine having 12 carbon atoms (manufactured by Kao Soap Co., Ltd., Firmin 20) was added (Comparative Example 5),
Magnesium stearate (manufactured by Kano Kagaku Co., Ltd., SM) 0.2
% (Comparative Example-6), ethylene bistearylamide (manufactured by Lion Armour Co., Ltd., AROMOWAX-
Table 1 also shows the results when 0.2% (EBS) was added (Comparative Example-7).

As can be seen from the results in Table 1, the polyamide resin composition according to the present invention suffers from deterioration of transparency that occurs when only aliphatic monoamine is added, occurrence of poor appearance of molded products, prolongation of plasticization supply time, and the like. It is clear that this is an excellent polyamide resin composition that has extremely excellent mold release properties and moldability that overcome these drawbacks of increased variation, and also maintains the transparency characteristic of polyamide resins.

Claims (1)

[Claims] 1 0.01 to 4% by weight of aliphatic monoamine having 14 to 22 carbon atoms and 0.01 to 4% by weight of polyamide resin
1. A polyamide resin composition comprising: fine particulate anhydrous silica having a specific surface area of 50 m''/? or more.