JP3380008B2 - Polyamide resin composition - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyamide resin composition having excellent moldability. More specifically, the present invention relates to a polyamide resin composition capable of giving excellent productivity and at the same time obtaining excellent molded article properties at the time of injection molding. [0002] Polyamide resins are widely used as engineering resins because of their excellent mechanical properties, heat resistance, oil resistance and the like. This polyamide resin is usually easily molded by injection molding or the like, but from the viewpoint of productivity and economy, a polyamide resin capable of shortening the molding cycle and achieving high production is required. I have. In response, a number of technical improvements have been attempted. For example, a polyamide resin composition containing at least one compound selected from the group consisting of barium stearate, barium laurate, aluminum stearate and the like (Japanese Patent Publication No. 41-8954), polysiloxane and periodic Polyamide resin composition obtained by adding a higher fatty acid salt of a metal selected from Tables I, II and III (JP-A-51-34257);
Polyamide resin composition containing a salt of an aliphatic carboxylic acid having 10 to 20 carbon atoms and an aliphatic carboxylic acid having 22 or more carbon atoms or a derivative thereof (JP-A-52-42549).
No.) are known. [0003] However, the polyamide resin composition obtained by these methods apparently shortens the molding cycle time by shortening the plasticization time and improving the releasability, If molding is performed with a reduced molding cycle time, the resulting molded product will have a large amount of warpage deformation, and in order to obtain a molded product for applications with strict dimensional accuracy, it is necessary to extend the molding cycle time to perform molding. Was. In addition, there is an increasing number of cases in which a molded article having a hinge portion is integrally molded by utilizing a feature that toughness is increased by absorbing water from a polyamide resin molded article. However, the thin hinge portion of the polyamide resin molded article is apt to bend and bend easily in a completely dry state where it does not absorb water. . [0004] In view of such circumstances, an object of the present invention is to shorten the plasticization time of a polyamide resin, improve the releasability, and shorten the molding cycle time.
Further, the present invention provides a polyamide resin composition having less warpage even when molding is performed with a shorter molding cycle time, and at the same time, the bending and foldability of a molded product hinge is improved even in a completely dry state. To provide a polyamide resin composition. The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found that a polyamide resin composition containing boron nitride powder and a derivative of an aliphatic carboxylic acid. However, they have found that all of the above problems can be solved, and have completed the present invention. That is, the present invention
(A) 100 parts by weight of a polyamide resin, (B) a powder of boron nitride having a powder particle size of 10 μ
A polyamide resin composition comprising 1 part by weight and (C) 0.005 to 0.5 part by weight of a derivative of an aliphatic carboxylic acid having 15 or more carbon atoms. It is the gist. Hereinafter, the contents of the present invention will be described in detail.
The polyamide resin used in the present invention is not particularly limited as long as it is a known polyamide resin, and includes those called nylon having a molecular weight of 5000 or more. Specifically, various types of polyamide resins such as polycondensates of lactams, polycondensates of diamine compounds and dicarboxylic acid compounds, polycondensates of ω-aminocarboxylic acids, and copolymerized polyamide resins and blends thereof. Things, etc.
For example, nylon 6, 66, 610, 612, 11, 1
Homopolymers such as 2, 46, nylon 66/6, 66 /
610, 66/612, 66 / 6T, 66 / 6I, 66
Copolymers such as / 6T / 6I and the like and blends thereof. Here, 6T is a condensate using hexamethylene diamine and terephthalic acid as raw materials, 6I is a condensate using hexamethylene diamine and isophthalic acid as raw materials, and the other is a polyamide resin using a known raw material. The boron nitride used in the present invention is represented by the chemical formula: BN. Boron is heated at a high temperature in a nitrogen stream, or is heated by heating ammonia and boron oxide, or ammonium chloride and borax. It is preferable to use a powder having a particle size of 10 μm or less, since if the particle size of the powder is large, structural defects occur and the effect of improving hinge characteristics cannot be obtained. The amount of boron nitride added is limited in relation to its function and effect. If the amount is less than 0.0001 part by weight with respect to 100 parts by weight of the polyamide resin, the intended effect is small and 1 part by weight. Exceeds 0.0001, the desired effect cannot be obtained.
It is necessary to contain it in the range of 1 part by weight, preferably in the range of 0.0005 to 0.5 part by weight. Boron nitride may be added at the time of polymerization of the polymer, or may be added by a known method such as being added to a polyamide in an extruder, being added to the pellet surface by blending, or added as a high-concentration masterbatch. The derivatives of aliphatic carboxylic acids having 15 or more carbon atoms used in the present invention include palmitic acid, stearic acid, behenic acid, cerotic acid, montanic acid, melicic acid, celloplastic acid, oleic acid, erucic acid and the like. Metal salts and esters. The amount of the aliphatic carboxylic acid derivative having 15 or more carbon atoms to be added is limited in relation to its function and effect. That is, if the amount is less than 0.005 parts by weight with respect to 100 parts by weight of the polyamide resin, it is intended. The effect is small, and even if it exceeds 0.5 part by weight, no further effect can be expected. Therefore, it is necessary to contain it in the range of 0.005 to 0.5 part by weight. The derivative of the aliphatic carboxylic acid having 15 or more carbon atoms can be compounded by a known method such as compounding with polyamide in an extruder, blending and adding to the pellet surface, or adding as a high-concentration masterbatch. In the polyamide resin composition of the present invention, other additives such as a spreading agent, an antistatic agent, a coloring agent, a filler, a reinforcing agent, and a stabilizer are used as long as the effects of the present invention are not significantly impaired. Can be added at any stage. Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. In Examples and Comparative Examples, the plasticizing time, the molding cycle time at which the mold could be released, the amount of warpage, and the hinge characteristics were measured by the following methods. (1) Plasticization time (molding condition) Injection molding machine: PS4 manufactured by Nissei Plastic Industry Co., Ltd.
0E Mold: 1 box (see Fig. 1) Cylinder temperature: 280 ° C at nozzle, 280 at front
C, middle 280 ° C, rear 280 ° C Mold temperature: 80 ° C Plasticization stroke: 12 mm Screw rotation speed: 250 rpm Back pressure: 10% Injection speed: 40% Injection pressure: 30% Molding cycle time: Injection 2 sec, cooling 13 sec
c, rest 0.3 sec (total 18.3 sec) (Measurement method) The average value of the plasticization time from 31 shots to 40 shots from the start of molding was determined. (2) Molding cycle time capable of releasing (measuring method) Molding is performed under the same conditions as in the measurement of the plasticizing time, and the total amount of the mold release failure when 50 shots are continuously molded while shortening only the cooling time is reduced. The molding cycle time was determined. (3) Warpage Deformation (Measurement Method) Under the same conditions as in the measurement of the plasticization time, only the cooling time is changed, and the total molding cycle time is 1
The warpage of the molded product was measured at 2.3 sec and 20.3 sec. The measurement site is the site shown in FIG. (4) Hinge characteristics (molding conditions) Injection molding machine: PS4 manufactured by Nissei Plastic Industry Co., Ltd.
0E Mold: Molded product with hinge (see Fig. 2) Cylinder temperature: 280 ° C at nozzle, 280 at front
C., middle 280 ° C., rear 280 ° C. Mold temperature: 80 ° C. Plasticizing stroke: 15 mm Screw rotation speed: 200 rpm Back pressure: 10% Injection speed: 40% Injection pressure: 23% Molding cycle time: Injection 7 sec, cooling 7 sec,
Pause 1 sec (Measurement method) The hinged molded article of FIG. 2 molded under the above molding conditions was bent 180 ° in an absolutely dry state, and the number of times of folding when broken was measured. The polyamide resin compositions of Examples and Comparative Examples were obtained as follows. Molecular weight 16,00
The amount of the composition shown in Table 1 was mixed with 100 parts by weight of nylon 66 of No. 0 using a Henschel mixer for 3 minutes. These polyamide resin compositions were molded and measured under the conditions described above, and the physical properties shown in Table 1 were obtained. [Table 1] According to the present invention, the problems encountered in the prior art, namely, shortening of the plasticization time of the polyamide resin, improvement of the releasability, and shortening of the molding cycle time have been achieved. Even when the cycle time is shortened, the warpage is small, so even if the molding cycle time is shortened to improve productivity, it is possible to obtain molded products for applications where dimensional accuracy is severe. It became. Furthermore, with respect to the bending breakage of the thin hinge part in a dry state in a dry state, the improvement of the present invention eliminates the need for a humidity control step, thereby contributing to an improvement in productivity.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view of a one-piece box molded product for measuring the amount of warpage deformation of the molded product according to the present invention, (A) is a plan view, and (B) is a cross-sectional view. (C) is a side view in which warpage deformation has occurred. FIGS. 2A and 2B are diagrams of a molded product used for measuring the number of times the hinge portion is bent in the present invention, wherein FIG. 2A is a plan view, FIG. 2B is a cross-sectional view, and FIG. It is.

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Claims (1)

(57) [Claim 1] (A) 100 parts by weight of a polyamide resin,
(B) 0.0001 to 1 part by weight of a powder of boron nitride having a powder particle size of 10 μ or less, and (C) 0.005 to 0.5 part by weight of a derivative of an aliphatic carboxylic acid having 15 or more carbon atoms. And a polyamide resin composition.