JPS6246504A - Thermosetting resin magnet composition - Google Patents

Abstract

PURPOSE:To contrive improvement both in productivity and durability of the titled composition by a method wherein the composition, in which phenol resin is used as a hardening agent, is formed into an bonding agent for a plastic magnet in a state wherein a very small quantity of a cocatalyst is contained in various kinds of epoxy resin. CONSTITUTION:The bonding agent of weight ratio of 5-30%, consisting of epoxy resin, phenol resin and a cocatalyst, is mixed into various kinds of magnetic powder. The phenol resin is the reactive substance consisting of phenol or alkyl phenol and the like and formaldehyde, and also the phenol resin is the novolac type resin reacted by acid catalyst or the resol type resin reacted by alkaline catalyst. The adding quantity of each catalyst is to be 3% or less for resin composition, and a fibrous reinforcing material of 1-30% is added for the purpose of improvement of the heat-resisting property, strength and the like of the molded article. As this composition has the conservative stability of 1-6 months or thereabout at room temperature, no defective molded article is generated in the industrial production, and the deterioration in physical property due to the amine of magnetic powder can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plastic magnet composition, and more particularly to a heat-resistant, fast-curing plastic magnet formulation using a special epoxy resin as a binder.

Plastic magnets are compared to sintered permanent magnets.

Because it can be easily molded into complex shapes.

In recent years, the demand has increased significantly. However, most plastic magnets use various polyamide resins, ethylene plastics such as polyethylene and polypropylene, and heat-resistant plastics such as polycarbonate as binders for magnet powder because of their ease of molding. These binders are usually mixed in a weight ratio of 5-30%, and the physical, chemical, or mechanical properties of the resulting magnet molded products are largely due to the basic properties of the thermoplastic resin that is the binder. 9 For example, plastic magnets that use polyamide as a binder absorb water during practical use, causing two-dimensional changes, drying out and becoming brittle under high-temperature usage conditions, and even becoming deformed. If too much water is absorbed, the magnetic particles will deteriorate.

Even the characteristics as a magnet may change. Even if other thermoplastic resins are used, similar problems arise due to the inherent characteristics of the resins.

A recent patent application publication No. 60-98603 discloses a method of using an epoxy resin, which is a thermosetting plastic, as a binder to improve the properties of such plastic magnets. Thermosetting resin has high heat resistance, low water absorption, and is a material with little deformation or dimensional change during practical use, so it is a molded magnet that is far superior to plastic magnets using the thermoplastic resin binder. It can be easily assumed that this is the case.

In this patent application, the epoxy resins include linear aliphatic type, glycidyl ester type, glycidylamine type, alicyclic type,
For well-known epoxy resins such as bisphenol A type and Rivolac type 9, curing agents include menthene diamine metaphenylene diamine, diaminodiphenyl methane, diaminodiphenylsulfone, and amine-based curing agents.
Dicyandiamide and BF3-monoethylamine are used, and as acid anhydride curing agents, trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic anhydride, methylnasic anhydride-dispersed chlorendic anhydride, etc. are used.

It is said that an epoxy resin composition in which the heat deformation temperature of the cured product obtained by appropriately combining these epoxy resins and curing agents is 150° C. or higher is preferable as a binder for plastic magnets. However, the plastic magnet composition disclosed in this patent application has the following problems.

Compositions using amine-based curing agents have short storage stability, and in industrial production, their moldability deteriorates in a short period of time, making them impossible to mold. The amine compound used in large amounts reacts particularly with the highly active rare earth magnetic powder, degrading the magnetic properties. This characteristic is particularly noticeable when the molded product is used at high temperatures, which is a drawback. On the other hand, all acid anhydride-based curing agents have the disadvantage that they require a long curing time, for example, 0.5 to 18 hours, making them almost impractical for molding with molds. No matter how good the properties of the cured product are, the productivity is too low and there is a problem from the cost perspective of the molded product. It can be said that epoxy resin compositions used as binders have many problems to be solved from the viewpoints of practicality, industrial productivity, cost, and durability. We thought that the above-mentioned problems could be solved by epoxy resin compositions using curing agents other than physical ones, and as a result of various studies, we found that phenolic resin was used as a curing agent in various epoxy resins in the presence of an ylj amount of cocatalyst. We investigated the use of this composition as a binder for plastic magnets.

As a result, epoxy resin binders made of various epoxy resins mixed with trace amounts of co-catalysts such as tertiary amines and imidazole, and a curing agent such as phenol novolac, have gelation times of 9 seconds, for example. It has been found that gelation occurs within 60 seconds at the earliest, and a binder can be produced that can be removed from the mold within, for example, 120 seconds.

As a result, the plastic magnet composition using the binder according to the present invention can significantly shorten the molding cycle.Therefore, the cost of molded products can be significantly reduced.1 The storage stability of the composition is 1-1 at room temperature. Since it can last for up to 6 months, molding defects will not occur in industrial production, and the physical properties will not deteriorate due to amines in the magnetic powder. Therefore, the quality of the molded magnet will improve even under high-temperature usage conditions. The epoxy resins used in the present invention, which have been shown to have no deterioration, include bisphenol type,
Any type of epoxy resin can be used, such as phenol novolac type or glycysyl ester type, and the phenol reactant as a hardening agent is selected depending on the physical properties required as a binder.It is an addition condensation reaction product of phenol and formaldehyde and is solid. The novolak type, which has undergone a certain degree of reaction, has good workability. The phenol may be a reaction product of an alkylphenol such as cresol or meta-xylene with formaldehyde.

Curing accelerators include tertiary amines, various imidazoles, and BF.
3-piperidine, triazoles, imidazole complex salts, complex salts of aWi and imidazole, etc. can be used.

The magnetic powder used is hard ferrite, soft ferrite, rare earth transition metal type, alnico magnetic powder, manganese bismuth magnetic powder, but is not limited to magnetic powder. Rare earth magnetic powder with particularly high activity is titanium-based or silicon-based. Deterioration in the quality of magnetic powder can be improved by treating it with a surface treatment agent such as .

In order to further improve the quality of the magnet molded product according to the present invention, it may be necessary to perform post-curing.

The post-cure conditions are determined by the required quality of the magnet molded product or by the combination of the epoxy resin and the curing agent. The compositions according to the invention are significantly strengthened by the addition of 1-30% fibrous reinforcement.

Modulus of elasticity, heat resistance, dimensional stability, etc. can be improved.

Glass fibers, organic synthetic fibers, whiskers, mineral fibers, carbon fibers, etc. can be used as the wc fibrous reinforcing material.

Shiyu Hong-L- Barium ferrite 100g and 10g of cresol novolac type epoxy resin, novolac type phenol resin 5
A mixture of 1 g of 2-methylimidazole and 0.5 g of calcium stearate was mixed on a mixing roll at 90° C., cooled and pulverized to obtain a molding composition. This molding material was filled into a mold at 150° C. and heated and pressed for 120 seconds. The cured product could be easily taken out from the mold.

Even in this state, it maintained sufficient strength for practical use.
In order to further improve the strength, post-curing was performed at 150°C for 5 hours, resulting in a 10% increase in bending strength.

LΔ9-1 Barium ferrite 100g and cresol type epoxy 1
0 g, trimellitic anhydride 3.3 g, hensyl methylamine 0.1 g, and calcium stearate 0.5 g were mixed using a mixing roll at 90°C, cooled, and pulverized.
It was used as a molding material. Even after heating and pressurizing the mold at a temperature of 150° C. for 10 minutes, the molded product could not be taken out from the mold.

100 g of tΔ1-tbarium ferrite, 10 g of bisphenol-type epoxy, 3 g of diaminodiphenylmethane, and 0.5 g of calcium stearate were mixed with a mixing roll at 80° C., cooled, and crushed to obtain a molding material. This composition is 1
It took 15 minutes to mold with a mold at 50℃, but the molding material was 40℃.
When kept at ℃ for 2 days, the moldability significantly decreased and molding became impossible.
,Zr)? ) 100g of silane coupling agent (KB
A molding material was prepared using the same composition 9 method instead of the one treated with M603). This composition could be taken out of the mold in 120 seconds using a mold at 150°C.

The magnetic flux densities of the samples immediately after molding and the samples post-cured at 150°C for 8 hours were measured at room temperature and after the heat resistance test at 200°C.

萱・　　　　　　　　　...　.

Comparative example 1 4.5 Comparative example 2 6,0 Example 2 non-stuck'=]? None 2. 1 post'r
7-A 1, 5 As is clear from these results, it is clear that the composition of the present invention causes less deterioration in the performance of magnetic powder than other compositions.

Support 1 - 1

Claims (1)

[Scope of Claims] 1. A thermosetting resin magnet molding composition in which 5 to 30% by weight of a binder consisting of an epoxy resin-phenol resin-promoter using a phenol resin as a hardening agent is mixed into various magnetic powders. 2. A patent claim characterized in that the phenol resin described in claim 1 is a reaction product of phenol or alkylphenols and formaldehyde, and is a novolac type resin reacted with an acid catalyst or a resol type resin reacted with an alkali catalyst. Composition of Range 1. 3. The composition according to claim 1, wherein the various promoters are added in an amount of 3% or less based on the resin composition. 4. The composition according to claim 1, in which 1 to 30% of a fibrous reinforcing agent is added to improve the heat resistance, strength, etc. of the molded product.