JPS63128072A - Polyamide resin composition - Google Patents

Abstract

PURPOSE:To provide a composition for plastic magnet having excellent heat- resistance and dimensional stability in water-absorption and containing a barium ferrite and a polyamide resin composed of xylylenediamine and an alpha,omega-straight- chain aliphatic dibasic acid. CONSTITUTION:The objective composition can be produced by compounding (A) 100pts.wt. of a polyamide resin having a number-average molecular weight of 10,000-40,000 and produced by the polycondensation reaction of (i) m- xylylenediamine or its mixture with <=40mol% p-xylylenediamine with (ii) an alpha,omega-straight-chain aliphatic dibasic acid (preferably adipic acid) or a blend of said polyamide resin and <=40wt%, preferably <=20wt% other polyamide resin (e.g. nylon 66, nylon 46, etc.) with (B) 350-1,150pts.wt. of a barium ferrite having an average particle diameter of 0.5-3.5mu and extruding and kneading the mixture.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a polyamide resin composition for plastic magnets having excellent heat resistance, dimensional stability upon water absorption, and mechanical properties.

[Conventional technology]

In recent years, various plastic magnets have been used in electronic parts, automobiles, audio equipment, rotating equipment, OA equipment, home appliances, etc.

Although plastic magnets generally have lower magnetic properties than sintered magnets, they have a lower specific gravity and can be lighter, and have less mold shrinkage, so they can be manufactured with high dimensional accuracy without post-processing, making it possible to produce products with complex shapes and thin walls. It has the advantage of being easy to make. Moreover, since it can be manufactured by injection molding, it is also excellent in mass production.

When barium ferrite is used in plastic magnets, the required magnetic properties are generally that the residual magnetic flux density Br is 1
400-1500 (Gauss), holding power BHC is 11
It is about 00 (Oersted).

Types of resins used in plastic magnets include nylon 12, nylon 6, nylon 66, polypropylene, polyphenylene sulfide, epoxy resin, etc., but nylon-based nylon 12 and nylon 6 are mainly used.

However, when these nylons are used as binder resins, it cannot be said that they have sufficiently satisfactory properties. For example, nylon 12 has excellent dimensional stability when absorbing water but does not have sufficient heat resistance, and nylon 6 has excellent heat resistance but has problems with dimensional stability when absorbing water. The reality is that each is used differently depending on its purpose.

[Problem that the invention seeks to solve]

The purpose of the present invention is to improve the problems of the prior art and obtain a polyamide resin molding material for plastic magnets that has excellent heat resistance, excellent dimensional stability when absorbing water, and good magnetization. do.

[Failure to solve the problem]

As a result of intensive research, the present inventors found that xylylenediamine and α
The above object has been achieved by using a polyamide resin obtained from .

The present invention provides a polyamide resin obtained from xylylene diamine and an α,ω-linear aliphatic dibasic acid, or a polyamide resin obtained by partially adding another polyamide resin (for example, nine 66, nylon 46) to the polyamide resin. polyamide resin 100
The present invention relates to a polyamide resin composition for a plastic magnet containing 350 to 1150 parts by weight of barium ferrite having an average particle size of 0.5 to 3.5 μm.

The polyamide resin obtained from xylylene diamine and α, ω-linear aliphatic dibasic acid as used in the present invention generally refers to It refers to a polyamide resin (hereinafter referred to as rMX-nylon) obtained by a polycondensation reaction from an amine and an α,ω-linear aliphatic dibasic acid.

When xylylene diamine used as a raw material contains para-xylylene diamine, the proportion of para-xylylene diamine in the xylylene diamine is preferably 40 mol% or less from the viewpoint of polymer synthesis or molding processing. .

α, ω-linear aliphatic dibasic acid has 6 to 1 carbon atoms.
Two aliphatic dicarboxylic acids such as adipic acid, superric acid, sebacic acid, undecaniic acid, dodecandioic acid, etc. can be used.

However, in a resin composition containing MX-nylon and barium ferrite, MX-nylon obtained by using adipic acid as an α,ω-linear aliphatic dibasic acid used as a raw material for MX-nylon has a high heat resistance. , giving molded products with excellent performance in terms of dimensional stability.

The composition of the present invention containing barium ferrite is characterized by excellent elastic modulus, low water absorption, and little change in dimensions, mechanical properties, and thermal properties due to water absorption.

On the other hand, a resin composition containing barium ferrite in MX nylon has a high glass transition temperature;
Injection molding at a mold temperature near room temperature may result in a molded product with insufficient crystallization. The crystallization rate can be increased by increasing the cooling time, but in this case it is necessary to increase the molding cycle time.

This problem of long molding cycle time can be easily solved by adding another polyamide resin with a melting temperature higher than the melting temperature of MX-nylon (243°C) and setting the mold temperature higher. .

Other polyamide resins to be added include nylon 66,
Examples include nylon 46.

The number average molecular weight of the MX-nylon used in the composition of the present invention is in the range of 10,000 to 40,000, but from the viewpoint of fluidity during molding, when barium ferrite is highly filled, it is preferable that the molecular weight is small.

Regarding the other polyamide resins to be added, it is preferable that they have a small molecular weight and good fluidity for the same reason.

In addition, the amount of other polyamide resin added to MX-nylon should be 40% by weight or less, preferably 20% by weight or less, particularly preferably 10% by weight or less, based on the total amount of polyamide resin, in order to improve the mechanical properties of the molded product. This is desirable in order to maintain performance such as dimensional stability during water absorption.

The barium ferrite used in the present invention has an average grain size of 0.
It has a diameter of 5 to 3.5μ. Also, for particles in this particle size range,
It is also possible to use a material that has been surface treated with a surface treatment agent such as a silane coupling agent.

The molded article obtained using the composition of the present invention can be magnetized by placing the molded article in a static magnetic field of about 10,000 oersteds.

Magnetic properties include residual magnetic flux density Br (Gauss), coercive force
BHC (Oersted) and (BHC) max =
It is determined from the value of B r-BHC/4.

That is, it is said that the higher the values of Br and BHC, the better the magnetizability.

When flame retardancy is required, various flame retardants can be added to the composition of the present invention.

In this case, known flame retardants can be used, but phthalocyanine green, decabromo biphenyl ether, hexachlorocyclopentadiene derivatives, brominated polystyrene and the like are preferred.

In addition, a rubber component for improving impact resistance, an antistatic agent, a lubricant, etc. may be added to the composition of the present invention, if necessary.

Methods for blending and kneading the composition of the present invention include a combination of a pressure kneader and a general extruder, a kneading method that applies shearing force such as a twin-screw presser or a disc type extruder, and barium ferrite is It can be blended up to 65Vo1%.

When a molded article is obtained by injection molding using a pelletized molding material obtained by kneading and extruding the composition of the present invention, the mold temperature is preferably in the range of 75 to 140°C.

If the mold temperature is 75°C or lower, crystallization is insufficient, resulting in a molded product with low heat resistance (particularly low heat distortion temperature).

On the other hand, at a mold temperature of 140° C. or higher, the molded product tends to become flexible, resulting in insufficient dimensional accuracy.

From the point of view of shortening the molding cycle, the mold temperature is particularly important.
The temperature range is preferably from 10 to 130°C.

[Action and effect of invention]

The composition of the present invention has excellent properties in both heat resistance and dimensional stability upon water absorption, as well as mechanical properties such as tensile strength, bending strength, and Izot impact strength, and magnetization properties. Furthermore, the present resin composition using barium ferrite has sufficiently satisfactory magnetic properties and is extremely useful as a material for plastic magnets.

〔Example〕

Next, the present invention will be specifically explained using examples.

In the examples, "parts" indicate parts by weight, and rp h rJ indicates the amount (parts by weight) of the surface treatment agent added to 100 parts by weight of barium ferrite.

In addition, physical property tests were conducted in the following manner.

(1) Specific gravity: ASTM D792 (2
) Tensile strength? ASTM D638 (3) Bending strength: ASTM D790 (4) Izot impact strength: ASTM D256 (5) Heat distortion temperature: ASTM D648 Examples 1 to 4 Polymethaxylylene adipamide with an average molecular weight of 14,500 (hereinafter abbreviated as nylon MXD6J) ) powder (10
0 mesh bath, manufactured by Mitsubishi Gas Chemical Co., Ltd.) T-aminopropyl triethoxysilane (trade name: A-1100, manufactured by Nippon Unicar Co., Ltd.) 0 in advance to 100 parts
．． A mixture containing 350, 500, 800, and 1150 parts of barium ferrite (trade name: DNP-8, average particle size: 1.2 to 1.4 μ, manufactured by Nippon Bengara Kogyo Co., Ltd.) surface-treated with 5 phr, Knead with a Henschel mixer and use a disc type extruder (KCK80-35VEX).
(6) (manufactured by KCK Co., Ltd.) after extrusion kneading, injection molding was performed at a mold temperature of 130°C.

Next, the magnetization characteristics (residual magnetic flux density (Gauss) and coercive force (Oersted)) of the molded product were measured using a BH curve tracer.

In addition, in order to measure the fluidity of the composition after kneading, a Koka type flow tester was used to determine the flow rate Q at 1 Tsuru φ x 11 layer L nozzle, 270°C, 10 kg/c++l.
Measurements were made.

The measurement results are shown in Table 1.

Example 5 γ-aminopropyl triethoxysilane (trade name: A-1100,
Barium ferrite (trade name: DNP-3, average particle size: 1.2-1.4μ, manufactured by Nippon Bengara Kogyo Co., Ltd.) 810 surface-treated with 0.5 phr (manufactured by Nippon Unicar Co., Ltd.)
The mixture was kneaded using a Henschel mixer, and then extrusion kneaded using a disk type extruder, followed by injection molding at a mold temperature of 130°C.

Table 2 shows the results of measuring the physical properties and magnetization characteristics of the obtained molded product.

Example 6 95 parts of nylon M, XD6 powder (100 mesh pass, manufactured by Mitsubishi Gas Chemical Co., Ltd.) and nylon 66 powder (
100 mesh pass, product name: Ami 970M3001N
, manufactured by Toshi Co., Ltd.), and barium ferrite (trade name: DNP-3) which had been surface-treated in advance with 0.5 phr of T-aminopropyl triethoxysilane (trade name: A-1100, manufactured by Nippon Unicar Co., Ltd.). , average particle size; 1
．． 2 to 1.4 μm, manufactured by Nippon Bengara Kogyo Co., Ltd.), and then kneaded and injection molded in the same manner as in Example 5, and the physical properties and magnetization properties of the resulting molded product were measured. went. The measurement results are shown in Table 2.

Example 7 95 parts of nylon MXD6 powder (100 mesh pass, manufactured by Mitsubishi Gas Chemical Co., Ltd.) and nylon 66 powder (1
00 mesh pass, product name: Ami 970M3001N,
5 parts (manufactured by Toshi Co., Ltd.) and barium ferrite (product name: DNP-3, surface-treated in advance with 0.5 phr of γ-aminopropyl triethoxysilane (product name: A-1100, manufactured by Nippon Unicar Co., Ltd.)). Average particle size; 1.
2 to 1.4μ, manufactured by Nippon Bengara Kogyo Co., Ltd.), and 10 parts of Phthalocyanine Green (trade name: YL Susu, manufactured by Toyo Ink Manufacturing Co., Ltd.) as a flame retardant were mixed, and the same process as in Example 5 was carried out. UL94V at 1/16 inch thickness
A molded article with flammability of -0 was obtained.

Table 2 shows the results of measuring the physical properties and magnetization characteristics of the obtained molded product.

Example 8 95 parts of nylon MXD6 powder (100 mesh pass, manufactured by Mitsubishi Gas Chemical Co., Ltd.) and nylon 66 powder (1
00 Me Noche Pass, Product Name: Ami 970M3001N
, manufactured by Toshi Co., Ltd.), and barium ferrite (trade name: DNP-3), which had been surface-treated in advance with 0.5 phr of γ-aminopropyl triethoxysilane (trade name: A-1100, manufactured by Nippon Unicar Co., Ltd.). , average particle size: 1.
2 to 1.4μ, manufactured by Nihon Bengara Kogyo Co., Ltd.), and 10 parts of hexachlorocyclopentadiene derivative (trade name: Dechlorane Plus 515, manufactured by Hooker Chemical Co., Ltd.) as a flame retardant were blended. 1/ in the same way as
A molded product having a thickness of 16 inches and a flammability rating of UL94V-O was obtained.

Table 2 shows the results of measuring the physical properties and magnetization characteristics of the obtained molded product.

Comparative Example 1 0.5 phr of γ-aminopropyl triethoxysilane (trade name: A-1100, manufactured by Nippon Unicar Co., Ltd.) was added in advance to 100 parts of nylon 6 powder (trade name: 1011F, manufactured by Ube Industries, Ltd.). Surface-treated barium ferrite (trade name: DNP-3, average particle size: 1.2~
1.4μ, manufactured by Nippon Bengara Kogyo Co., Ltd.) were blended, and a molded product was obtained in the same manner as in Example 5.

Table 2 shows the results of measuring the physical properties and magnetization characteristics of the obtained molded product.

Comparative Example 2 T-aminopropyl and
Barium ferrite (trade name: DNP-S, average particle size: 1.2) surface-treated with 0.5 phr of triethoxysilane (trade name: A-1100, manufactured by Nihon Unicar Co., Ltd.)
~1.4μ, manufactured by Nippon Bengara Kogyo Co., Ltd.) was blended with 810 parts, and a molded product was obtained in the same manner as in Example 5.

Table 2 shows the results of measuring the physical properties and magnetization characteristics of the obtained molded product.

Chapter 1 Table Table 2 Procedural amendment cap button July 8, 1986

Claims (1)

[Claims] (1) Polyamide resin obtained from xylylene diamine and α,ω-linear aliphatic dibasic acid, or polyamide resin 10 consisting of this polyamide resin and another polyamide resin
A polyamide resin composition in which 350 to 1150 parts by weight of barium ferrite with an average particle size of 0.5 to 3.5 μm is blended to 0 parts by weight.