JPH09235464A - Polyamide resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyamide resin compsn. which is excellent in mold release characteristics and generates a gas little by compounding a polyamide resin with an fatty acid amide and an aliph. carboxylic acid or its ester. SOLUTION: A hundred (100) pts. polyamide resin, which may be one of various nylons or multicomponent copolymer nylons, is mixed and kneaded with 0.05-1 pt. unsatd. fatty acid amide derived from a 6-22C unsatd. fatty acid [e.g. an ethylenebis-(unsatd. fatty acid) amide or a methylenebis-(unsatd. fatty acid) amide], 0.005-0.5 pt. component selected from among a 22C or higher aliph. carboxylic acid (e. g. behenic or lignoceric acid) or its metal salt, an ester of a carboxylic acid with a dihydric aliph. alcohol, and a partially saponified ester compd., and if necessary further with a colorant, an antioxidant, a flame retardant, a reinforcement, etc., and extruded to give a polyamide resin compsn., which is injection molded to give a molded article.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyamide resin composition having excellent mold releasability at the time of molding and having little mold stain even when continuously molded.

[0002]

Polyamide resin is an engineering plastic having excellent impact resistance, chemical resistance, and self-lubricating properties, and has been widely used for a long time in textiles, electrical parts, machine parts, films, automobile parts, etc. However, molding was performed relatively easily.

However, in recent years, improvement in productivity has been demanded from the economical aspect, and the injection molding cycle has been shortened. Further, since the shape of the molded product has become complicated by increasing the functionality of the product, the releasability has been improved.

As these methods, it is proposed to use a polyamide resin with a lubricant such as an aliphatic hydrocarbon type, a higher fatty acid, an aliphatic alcohol, a fatty acid amide, a fatty acid ester and a metal soap, or a release agent to improve the releasability. (Japanese Patent Publication No. 38-20723 and Japanese Patent Laid-Open No. 58-
157855, etc.).

[0005]

However, these additives have poor thermal stability and act as a mold release agent, but on the other hand, they are easily decomposed as a gas, and the effect of this gas stains the mold surface, If molding is performed for a long period of time in order to increase the mold release force, mold release defects often occur. Therefore, as a result of disassembling and cleaning the mold, there is a problem that productivity is deteriorated.

Therefore, a measure for reducing the amount of gas generated by reducing the amount of the additive compounded is taken, but with this, the releasing force becomes large and releasing defects are likely to occur.

In order to solve such a situation, the present invention provides
It is an object of the present invention to provide a polyamide resin composition which has an excellent releasing property and a small amount of generated gas.

[0008]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that by combining a specific mold release agent with polyamide and blending them at a specific ratio, excellent results are obtained. It has been found that the generated gas is significantly reduced while having the releasing property, and finally the present invention has been completed.

That is, the present invention comprises: (A) polyamide resin: 100 parts (B) unsaturated fatty acid amide compound: 0.005-1 parts and (C) aliphatic carboxylic acid or its ester compound:
A polyamide resin composition containing 005 to 0.5 part.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. In the present invention, the number of parts means the number of parts on the basis of mass.

The polyamide resin used in the present invention is not particularly limited, but various types of nylon or their multi-component copolymerized nylons such as N6, N6, 6, and the like can be used.
H6, N11, N12 and other homopolymers, N6
/ 6.6, N6 / 6/10, N66 / 610, N6 / 1
2, N66 / 12, N6 / 6T (T means a structure derived from terephthalic acid), N66 / 6T and other copolymers, and even more multi-component copolymers, especially N66 and N6 homopolymers. Or N6 / 66
Are preferred. Further, a polymer alloy obtained by blending the above polymer with another polymer such as polyolefin or polyester may be used.

As the unsaturated fatty acid amide compound used in the present invention, those having a structural part derived from unsaturated fatty acid having 6 to 22 carbon atoms are preferably used. Examples of the unsaturated fatty acid include palmitoleic acid and oleic acid. , Gadrenic acid and erucic acid are preferred. Further, those having two amide structures, that is, unsaturated fatty acid bisamides are preferably used, and among them, ethylene bis unsaturated fatty acid amides and methylene bis unsaturated fatty acid amides are preferable. As specific compounds, ethylene bis oleic acid amide and ethylene bis erucic acid amide are preferably used.

The unsaturated fatty acid amide compound used in the present invention is 0.0
05 to 1 part, preferably 0.03 to 0.7 part, and more preferably 0.1 to 0.5 part. If it exceeds 1 part, the amount of generated gas is large and the mold is easily soiled.
Those less than 05 parts tend not to have excellent releasability.

In the aliphatic carboxylic acid or its ester compound used in the present invention, an aliphatic carboxylic acid having a structure of 22 or more carbon atoms is preferably used. Examples of such carboxylic acid include behenic acid, lignoceric acid, cerotic acid, montanic acid, and mericic acid. Also,
Metal salts including these alkali metals such as Na and K and alkaline earth metals such as Ca and Mg can also be used. As the ester compound of carboxylic acid, ester of carboxylic acid and aliphatic dihydric alcohol is preferably used, and partially saponified product can be used. As such an aliphatic dihydric alcohol, ethylene glycol, propylene glycol, butylene glycol or the like is used. Specific examples of these additives include Hoechst Japan Co., which oxidizes montanic acid <Hoechst wax S>, and partially esterifies montanic acid with butylene glycol, and partially saponifies the rest with calcium hydroxide <Hoechst. Wax OP> can be used.

Further, the mixing ratio of the aliphatic carboxylic acid or its ester compound used in the present invention is 0.005 to 0.5 part per 100 parts of the polyamide resin, in the sum.
Preferably, 0.01 to 0.4 part, and 0.01 to 0.
2 parts, more preferably 0.05 to 0.3 part. If the amount exceeds 0.5 parts, the generated gas is large and the mold is easily soiled. If the amount is less than 0.005 parts,
They tend not to have excellent release properties.

The polyamide resin composition of the present invention can be manufactured by a known method. That is, the polyamide resin is mixed with the release agent, and the mixture is kneaded and extruded.
Alternatively, it can be easily produced by adding these compositions during the polymerization of the polyamide resin. Or,
It is also possible to externally add the above-mentioned release agent to the polyamide resin. As a method of external addition, dry blending is generally used, but there is also a method of blending the release agent into master pellets.

The resin composition of the present invention contains the above-mentioned components as essential components, but if necessary contains other colorants, antioxidants, flame retardants, inorganic fine particles, inorganic reinforcing agents, and release agents. Good.

The polyamide resin composition of the present invention is
Injection molded into a molded product.

[0019]

EXAMPLES The present invention will be described below with reference to examples.

(Examples 1 to 13, Comparative Examples 1 to 14) N6
100 parts of 6 chips (1 g / 100 ml at 25 ° C.-relative viscosity of 2.9 measured with 98% sulfuric acid solution) were mixed with 100 parts of the additives and amounts shown in Table 1 and pelletized with an extruder to obtain a composition. It was

[0021]

[Table 1] EBO: Ethylenebisoleic acid amide (unsaturated fatty acid amide) EBA: Ethylenebisstearic acid amide (saturated fatty acid amide) HW-OP: Hoechst wax OP (manufactured by Hoechst Japan)

[0022]

[Table 2] EBO: Ethylenebisoleic acid amide (unsaturated fatty acid amide) EBA: Ethylenebisstearic acid amide (saturated fatty acid amide) HW-OP: Hoechst wax OP (manufactured by Hoechst Japan)

The pellets thus obtained were put into a PS-60 type injection molding machine manufactured by Nissei Plastic Industry Co., Ltd., with a wall thickness of 2 mm,
Injection molding was carried out using a mold that provided a box-shaped molded product having an outer dimension of 40 × 40 × 60 mm (vertical × horizontal × high) without a bottom lid. It should be noted that this molded product is dug into the movable side of the mold, and has a mechanism for releasing the mold by ejecting the top plate of the box with an ejector.

The molding conditions were a resin temperature of 285 ° C., a mold temperature of 80 ° C., an injection time of 10 seconds and a cooling time of 10 seconds.

The releasing force is expressed by the force applied to the ejector when the molded product is ejected, and it is 10 times continuous from the 11th shot.
The average value of shots was defined as the initial release force.

Further, continuous molding was carried out, and the number of shots until the ejector broke through the molded product to make it impossible to mold-release, was defined as long-term mold releasability.

The amount of generated gas is expressed by the amount of mass reduction after putting 20 g of pellets in an aluminum cup and heating in air at 280 ° C. for 2 hours, and the amount of generated gas per hour is 0.5%. Exceeding (x), 0.2 to 0.5%
Those having a value of (Δ) were evaluated as those having a content of less than 0.2% (A). The smaller the generated gas amount, the less the mold stains.

From Table 1, it can be seen that the polyamide resin composition of the present invention has a small initial mold releasing force as compared with the resin composition of the comparative example and has a stable mold releasing property for a long period of time, and in particular, it is generated. It can be seen that the amount of gas is also small.

[0029]

EFFECTS OF THE INVENTION The polyamide resin composition of the present invention has excellent mold releasability, generates a small amount of gas, and has little mold fouling even during continuous molding. .

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiko Konami 1-9-9 Oe-cho, Minato-ku, Nagoya-shi, Aichi Toray Co., Ltd.

Claims (7)

[Claims] 1. (A) Polyamide resin: 100 parts (B) Unsaturated fatty acid amide compound: 0.005 to 1 part (C) Aliphatic carboxylic acid or its ester compound: 0.
A polyamide resin composition containing 005 to 0.5 part. 2. The polyamide resin composition according to claim 1, wherein the unsaturated fatty acid amide compound is an unsaturated fatty acid bisamide. 3. The polyamide resin composition according to claim 1, wherein the aliphatic carboxylic acid has 22 or more carbon atoms. 4. The polyamide resin composition according to claim 1, wherein the aliphatic carboxylic acid or its ester compound is an aliphatic carboxylic acid having 22 or more carbon atoms or its diol ester. 5. The unsaturated fatty acid bisamide is ethylenebisoleic acid amide.
4. The polyamide resin composition according to any one of 4 above. 6. The polyamide resin composition according to claim 1, which is for injection molding. 7. A molded product obtained by injection molding the resin composition according to claim 6.