JPS62190256A - Magnetic plastic composition - Google Patents

Abstract

PURPOSE:To obtain a magnetic plastic composition capable of giving a plastic magnet having excellent magnetic characteristics, mechanical properties and mass-productivity, by compounding potassium titanate whisker, magnetic powder and a plastic. CONSTITUTION:Potassium titanate whisker of formula I or formula II (n is 4-12, preferably 6-8; m is preferably 0.1-0.7) having true specific gravity of preferably 3.3-3.5, a melting point of 1,300-1,350 deg.C and Mohs hardness of about 4 and free from lump of fibers or foreign materials is used as a raw material optionally after surface-treatment with a coupling agent. (A) a small amount (preferably 0.5-5pts.wt. per 100pts. of the final composition) of the potassium titanate whisker is simultaneously mixed with (B) a magnetic powder, e.g. powder of hard ferrite, etc., and (C) a plastic. If necessary, the mixture is further added with a coupling agent, plasticizer, lubricant, surface protecting agent, colorant and reinforcing agent.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a plastic magnetic composition with improved mechanical strength.

(Prior Art) A plastic magnet is a magnet manufactured using a plastic molding method. In principle, the composition consists of magnetic powder and plastic, but various additives are usually used to improve magnetic properties, strengthen mechanical properties, or improve heat resistance.

For example, to improve magnetic properties, it is important to select an appropriate lubricant and coupling agent, and to strengthen mechanical properties, it is important to select the type of plastic as well as the combination of coupling agents.

On the other hand, the shape and dimensions of plastic magnets tend to be considerably more complex, thinner, and smaller than conventional rare earth or ferrite sintered magnets. For this reason, there is a particular need for plastic magnets to have stronger mechanical properties, and various studies are being carried out. For example, polycarbonate or ionomer, which inherently have excellent mechanical properties, may be used as a plastic, or a coupling agent may be used as an additive. However, the use of plastics with excellent mechanical properties often results in a decrease in magnetic properties and is poor in mass production.Currently, polyamide (nylon) based plastics are used as base resins. many.

In addition, the use of a coupling agent requires an additional coupling reaction step and usually does not improve the mechanical properties very much, so it is currently used more as a protective coating against oxidation and deterioration of magnetic powder. The meaning is getting stronger.

For simple reinforcement purposes, conventional plastic reinforcements such as glass fibers, carbon fibers, mica, etc. can be used, but these reduce the volume fraction of the magnetic component in the magnetic composition and, as a result, reduce the magnetic strength. It is not normally used because it causes a significant deterioration in properties.

(Problems to be Solved by the Invention) The object of the present invention is to have excellent magnetic properties and mechanical strength,
Another object of the present invention is to provide a plastic magnetic composition that provides a plastic magnet that is excellent in mass production.

(Means for Solving the Problems) The present invention relates to a plastic magnetic composition containing potassium titanate whiskers, magnetic powder, and plastic.

The present inventors have found that the above technical i! ! ! The present invention was achieved by discovering the fact that this problem was solved and that other properties did not deteriorate.

In the present invention, the potassium titanate whisker has the general formula 2O-nTiOz or K20-nTio2
"A+820" is a monoclinic fine needle-shaped crystal.The first value here is not necessarily an integer, but the reason is that the potassium component is extracted during the manufacturing process of the whisker. n can take a value of 4 to 12. In the present invention, n is particularly preferably in the range of 6 to 8. Also, the spear is extracted from the crystal structure of the whisker and emptied. It represents crystal water that is thought to exist as oxonium ions at the potassium ion site, and does not include free water simply adsorbed on the surface.The value is 0.
．． The range of 1 to 0.7 is preferable.

The whiskers used in the present invention can be used in a wide range of sizes, from fine ones to slightly coarse ones, and, for example, fine whiskers have an average diameter of 0.2 to 0.
It is possible to use a whisker having an average fiber length of 5 μm/10 to 20 μm and an aspect ratio of around 40 (hereinafter referred to as whisker A). In addition, the average diameter of slightly coarse ones is 1.
A whisker having an average fiber length of 50 to 150 μmfi and an aspect ratio of about 30 to 50 (hereinafter referred to as whisker B) can also be used. Items with sizes in between these can also be used.

Moreover, those having a slightly smaller or larger size can also be used in the same way.

The true specific gravity of whiskers is 3.3-3.5, and the melting point is 1300.
A relatively soft material with a moss hardness of about 4 to 1350°C is preferable, and a material with a high tensile strength of several GPa and excellent reinforcing properties is preferable.

It is desirable that the potassium titanate whiskers used in the present invention contain as little as possible clumps of fused fibers and clumps of foreign matter. However, it may cause problems such as variations or reduction in component strength.

The whiskers can be used as they are or after surface treatment with a suitable coupling agent. The type and amount of coupling agent, and treatment method can be selected depending on the matrix resin of the plastic magnetic composition. Sometimes about 1-2 depending on the use of coupling agents
In some cases, an improvement in the reinforcing properties of the openness can be seen, but usually the effect of contributing to improving the physical properties of the composition is not seen, and rather, it is applied for secondary effects such as improving the processing properties of whiskers. Examples of the magnetic powder used in the present invention include oxide-based ferrite called H-1-ferrite, and 5-11 CO9-based HS m2 (Co HF) called rare earth magnet.
e HCu, M)17. (M=Zr, Ti, l-
Examples include permanent magnets or powders of permanent magnet materials represented by 1F) series, Nd-Fc-B series, and the like.

Examples of the plastics used in the present invention include epoxy resins, unsaturated polyester resins, 7-El-O (fats), thermosetting resins such as melamine resins, polyolefins, polyvinyl chloride, and ABS.

Nylon, polybutylene terephthalate (PBT), polyacetal, modified polyphenylene oxide (pp
o ), polyphenylene sulfate (p p s
) and other thermoplastic resins.

As mentioned above, the potassium titanate whisker has a short fiber length of several tens to several hundred micrometers, and the aspect ratio is rather small compared to ordinary chopped strands of glass wLm. When used in plastic magnetic compositions, it exhibits an unexpectedly significant reinforcing effect even when added in a very small amount. That is, for common potassium titanate whiskers and thermoplastic compositions, the whiskers are
i1. However, in the case of the plastic magnetic composition of the present invention, with the addition of only 2% by weight of potassium titanate whiskers, the bending strength is only about twice that of the case without additives. 93 times as much as the value.

Therefore, the present invention is characterized in that the content of potassium titanate whiskers used in the plastic magnetic composition may be small. That is, from the balance between magnetic properties and mechanical properties, about 0% in 100 parts by weight of the composition.
．． 1 part of 5-5mff is suitable. However, the content is not necessarily limited to the above range.

In order to mix potassium titanate whiskers into a plastic magnetic composition, it is preferable to mix the whiskers at the same time as the plastic and magnetic powder are mixed. As the mixing device, various types of mixers, Brengu, Nigu, single-screw, twin-screw kneading and extrusion can be used.As the molding device, injection molding machines, compression molding machines, etc. can be used.Mixing and molding It is usually carried out in two stages, but in some cases it can also be carried out continuously in one device or simultaneously in a continuous manner using a plurality of devices.

Although the true specific gravity of potassium titanate whiskers is large, f/
The specific gravity is usually as low as about 0.2, which has the disadvantage of poor workability and poor mixing efficiency, but when the present invention is implemented, there is no problem with workability, mainly because the amount of whiskers added is low. . Therefore, various coupling agents are not necessarily required for the purpose of improving processability. When using coupling agents, silane-based, nathanate-based,
A coupling agent such as an aluminum-based coupling agent can be applied by a known method.

Plasticizers may be required depending on the matrix resin used, but are often not necessary. The type and amount of plasticizer to be used depends on the type of resin and the required performance of the molded product, and appropriate amounts of known plasticizers such as phthalate esters can be used. Known lubricants such as stearate metal salts, molybdenum disulfide, and fluorine O (fat powder) may be used if required.Other various additives such as surface protectants, colorants, reinforcing agents, etc. may be used as necessary. Any known material can be used as appropriate.

(Example) Next, the present invention will be explained with reference to an example. Note that parts simply indicate parts by weight.

Example 1 91 parts of 5IT12 (Co, Fe, Cu, Zr) 17-based magnetic powder, 7 parts of 12-nylon, and 2 parts of a total of calcium stearate and potassium titanate whiskers (whisker A) as lubricants. Five types of compositions as shown in Table 1 were prepared by heat kneading.

This composition was injection molded in a magnetic field, and the magnetic field and bending strength of the resulting plastic magnet were measured, and the results are shown in Table 1.

From the results in Table 1 Pt51, it is clear that as the amount of potassium titanate whiskers added increases, the mechanical properties improve.
) or.

Example 2 An amount equivalent to 88 tons of strontillano, 7g-lye Y powder was added to γ-
After coupling treatment with aminopropylmethyldimethoxysilane, the total amount of 6-nylon and potassium titanate whiskers (whisker B) was set to 12 parts, and six types of plastic magnetic compositions as shown in m2F2 were prepared. was prepared by heat kneading. A sample consisting only of 90 parts of ferrite and 10 parts of 6-nylon was also prepared.

This composition was injection molded in a magnetic field, and the magnetic and bending strength measurements of the resulting plastic magnets were performed, and the results are shown in Table 12.

From the results shown in Table 2 ff52, it is clear that the addition of potassium titanate whiskers sufficiently compensates for the decrease in mechanical properties due to the decrease in plastic content.

(Effects of the Invention) As described above, if a plastic magnetic composition containing potassium titanate whiskers is used, plastic magnets with complex shapes or thin walls that require mechanical strength can be produced with large magnetic properties. It can be provided with excellent mass productivity without causing a wide decline.

(that's all)

Claims (2)

[Claims] (1) A plastic magnetic composition containing potassium titanate whiskers, magnetic powder, and plastic. (2) The plastic magnetic composition according to claim 1, further comprising at least one selected from coupling agents, plasticizers, lubricants, surface protectants, colorants, and reinforcing agents.