JPH02185540A - High-density plastic composition and preparation thereof - Google Patents

Abstract

PURPOSE:To obtain the title compsn. with excellent moldability and mechanical strength and a high specific gravity not obtained hetherto by filling a plastic material with each specified iron powder and metal (compd.) powder. CONSTITUTION:An iron powder with a particle diameter of 150mum or smaller prepd. by atomizing and a viscous and soft metal (compd.) powder (e.g. ferrite powder) with a specific gravity of 3 or larger and a particle diameter of 10mum or smaller are filled in a plastic material (e.g. nylon) in such a way that loadings of the iron powder and the metal (compd.) Powder are respectively 85-92wt.% and 4-15vol.% based on the compsn. by using pref. a screw-inline type injection molding machine to obtain the title compsn. where metal powders are highly filled.

Description

DETAILED DESCRIPTION OF THE INVENTION +al Industrial Application Field This invention relates to a high specific gravity plastic composition filled with metal powder or the like at a high concentration. Specifically, the present invention relates to a new composition that uses inexpensive atomized iron powder, has a high specific gravity that could not be achieved with conventional techniques, and has excellent moldability and mechanical strength, and a method for producing the same.

(b) Prior Art Conventionally, high specific gravity materials, which are plastic materials mixed with metal powders such as iron powder at high concentrations, have been used for mechanical parts and the like.

Typical applications for these include flywheels for tape recorders. Examples of prior art related to high specific gravity plastic compositions are as follows. Japanese Patent Publication No. 62-2124
No. 59 has a nylon 12 matrix and contains 82.5% iron powder. I got 3.63. Also special public service Sho 61-11261
In this issue, 74% zinc powder is blended with a steel 6 matrix, and the specific gravity is 3.
．． I am getting 0. Furthermore, as a technique for making a material with a higher specific gravity, JP-A No. 61-200165 discloses a composition with a specific gravity of 4°4 by blending 90% zinc powder and reinforcing fibers with a nylon 6 matrix; -169858 has a nylon 6 matrix and contains 85% iron powder to obtain a composition with a specific gravity of 4.34. Further, in JP-A-60-6738, a composite material having a maximum specific gravity of 4.42 is obtained by blending metal powder (mainly iron powder) and an inorganic filler.

That is, in the prior art, there was no method for stably and inexpensively manufacturing molded products with a specific gravity of 4.5 or more and excellent strength.

However, in recent years, high-density plastic materials are being considered for use in place of conventional flywheels because of their good processability. This conventional flywheel is made of iron made by powder metallurgy, cutting, etc.
These products are made of copper, alloys, etc., and by replacing them with injection molded products made of high-density plastic materials, it is possible to significantly improve productivity and reduce costs.

However, as mentioned above, high specific gravity materials made by conventional technology have a specific gravity of approximately 4.4, which is lower than the specific gravity of metal materials, such as 7.0 for iron products made by powder metallurgy and 8.8 for brass products made by cutting. .7, the dimensions must be larger than those of metal products, which runs counter to the demand for miniaturization of electrical products. Therefore, there has been a strong desire to improve the specific gravity of high-density plastic materials while maintaining workability and mechanical performance.

(Problems to be solved by the C1 invention The inventors of the present invention have conducted intensive research to develop a composite composition with a high specific gravity that could not be achieved with conventional technology in response to the market demand as described above. This invention was completed by developing a new method for producing compositions and molded products with a specific gravity of 4.5 or more in high specific gravity compositions containing inexpensive atomized iron powder as a main component.

+d1 Means to solve the problem The configuration of the present invention will be explained in detail below.

The present invention relates to a high specific gravity plastic composition containing a high concentration of metal powder, etc. The basic composition is 85 to 92% by weight of the metal powder mixture and 6 to 15% by weight of thermoplastic 411 fat. The metal powder mixture includes iron powder with a particle size of 150 μm or less made by an atomization method as the first component,
The second component is a mixture of a viscous metal powder or a metal compound having a particle size of 10 μm or less, preferably 5 μm or less and a specific gravity of 3 or more.

Examples of the second component of the flexible metal powder or metal compound powder include zinc powder (zinc dust) with a diameter of 5 μm or less, metal compounds such as zinc chromate, loess, titanium yellow, and cobalt green, barium ferrite, and strontium ferrite. Examples include fired bodies of mixtures of metal oxides such as iron oxide, iron oxide, and metal oxides such as antimony trioxide. However, this invention is not limited to the above example.

The metal powder or metal compound fine particles exemplified here are:
Both have strong stickiness and the powder itself has poor fluidity.
It has the effect of adhering to iron powder and nylon powder and preventing them from separating. Among these, ferrite type is preferable in terms of its function and cost.

In order to increase the specific gravity of the composition to 4.5 or more, which is the limit of the conventional technology, the total content of the first component of iron powder and the second component of metal powder or metal compound powder must be 85 to 92% by weight, and The two components account for 4 to 15% by volume of the composition, preferably 8 to 15% by volume.
It is essential that it be 12% by volume.

If the amount of the second component is smaller than this, the mixture of metal filler and resin powder will separate, resulting in large fluctuations in the specific gravity of the product, and in extreme cases, the composition may be damaged in the cylinder of an extruder or injection molding machine. No melt flow, screw rotation,
Progress comes to a halt.

Moreover, if the amount is more than this, the volume ratio of the metal filler system in the composition becomes large (and the moldability is significantly inhibited).

In particular, when molded products are produced by directly molding this composition using an injection molding machine, the appearance of each molded product such as weight, size, strength, surface gloss, etc. varies, making it impossible to produce stable products.

The second component powder needs to have a specific gravity of 3 or more, preferably 5 or more.

If the specific gravity is lower than this (k), the specific gravity of the composition cannot be raised above 4 or 5, which is the limit of the prior art. or,
Even if the powder is in a free-flowing form, the mixture will separate and stable molding will not be possible.

Due to these restrictions, barium sulfate, mica, talc, calcium carbonate, kaolin, titanium oxide, etc. are not included in the scope of this invention.

In the composition of the present invention, it is preferable that at least the atomized iron powder, preferably both the atomized iron powder and the metal compound, be subjected to a coupling treatment in advance, or that a coupling agent is added at the same time as blending with the resin raw material.

For this purpose, organosilane compounds such as γ-aminopropyltriethoxysilane, N-β(aminoethyl)γ-aminopropyltrimethoxysilane, N-phenyl-T-aminopropyltrimethoxysilane, γ-glycyltrimethoxysilane, A silane coupling agent such as sidoxypropyltrimethoxysilane or a zircoaluminate coupling agent having an organic ligand such as carboxy, aliphatic, or methacryloxy as an organic functional group can be used.

The optimal coupling agent differs depending on the resin to be blended.

T-aminopropyltriethoxysilane is preferred for nylon, and aliphatic zircoaluminate coupling agent is preferred for polybutylene terephthalate.

The compression agent is 0.001 to 2.0% for metal powder, etc.
It is particularly effective to add 0% by weight, preferably 0.01 to 1.0% by weight.

If the amount is less than this, the effect will be poor, and if more than this is added, the cost will only increase and no improvement in the effect will be seen.

The strength and rigidity of the highly concentrated metal powder mixture composition of the present invention can be further improved by incorporating various reinforcing materials. The reinforcing material added for this purpose is preferably a fibrous reinforcing material, particularly glass fiber.

The blending amount of glass fiber is 1% to 30%, preferably 10%.
% to 20%. Other fibrous reinforcements include calcium silicate (wollastonite), xonotlite, potassium titanate, gypsum fiber (Franklin fiber), MO
Examples include S (MgSO4.5 M g 0.8 HO) and asbestos.

The blending amount of these reinforcing materials is 1% to 40%, preferably 10% to 30% of the composition.

Many thermoplastic plastics can be used as the plastic compounded in the composition of the present invention. General high-density applications include vinyl chloride resin, low-density polyethylene, high-density polyethylene, polypropylene, high-impact polystyrene, AB
S resin etc. are suitable. Polyolefin resins include ethylene/propylene rubber,
It is also preferable to blend polybuclene rubber or the like.

For high strength and high specific gravity applications, higher performance engineering plastics such as nylon, polybutylene terephthalate, polyethylene terephthalate, polyacetal, polyphenylene sulfide, or other crystalline resins, or polycarbonate, polyphenylene ether-polystyrene blend resins, Amorphous resins such as polysulfone and polyarylate can be used.

These engineering plastics are known for their impact resistance,
It is often made into a polymer alloy for the purpose of improving stress cracking resistance, moldability, etc., and these are also included in the resin for this composition.

Modifiers that are added to give particularly high impact properties include ethylene-propylene rubber, styrene-butadiene brox copolymer and its hydrogenated products, and butyl acrylate elastomer.For nylon, these include unsaturated carboxylic acids or their anhydrides. It is well known that elastomers to which acrylic acid or maleic anhydride is added are effective.

However, the present invention is not limited by the above-mentioned resin.

Additionally, a stabilizer such as a phenol stabilizer or a phosphite stabilizer may be added to the mixture of the metal powder mixture and the resin to prevent coloring during molding, or methylene bisstearamide, stearic acid, or the like may be added to the mixture. It is also possible to use a common technique of adding a lubricant such as a metal salt or a moncitic acid ester to improve the mold releasability and surface smoothness of the molded article.

By melt-mixing (melt compounding) these mixtures by a conventional method, a high specific gravity plastic material can be easily produced.

It is also possible to form this mixture directly into a molded article using a screw injection molding machine.

As an injection molding machine used in this process, an injection molding machine equipped with a kneading mechanism described in Japanese Patent No. 1104727 is particularly suitable for carrying out the present invention because it has a great effect of uniformly dispersing the metal powder mixture. It has a great effect.

In the injection molding of the composition according to the present invention, a material supply device that operates in conjunction with the screw of the injection molding machine is attached, and the material is adjusted to be supplied into the cylinder of the molding machine in a starvation state. First, it is preferable to mold it.

This effect is due to the material being sufficiently degassed and the high viscosity material during the melting process preventing the screw from moving forward during injection. This is because it is extremely effective in manufacturing precision molded products by smoothly advancing according to the combination of position and injection speed.

However, the composition itself according to the present invention is of course not limited by these manufacturing methods.

(e) Function This invention consists of a mixture of 85 to 92% by weight of iron powder produced by an atomization method as a first component, a viscous metal compound with a particle size of 10 pm or less as a second component, and 85% to 92% by weight of a thermoplastic resin.
By blending the second component in an amount of 15% by weight and 4% to 15% by volume, preferably 8% to 12% by volume of the total composition, high concentration filling that could not be achieved with conventional techniques can be achieved. We have succeeded in developing a high specific gravity plastic composition with a specific gravity of 4.5 or more, which makes it possible to achieve this goal, has excellent moldability, and has excellent mechanical strength of molded products.

Furthermore, the present invention has also developed a method for efficiently manufacturing molded articles from the composition.

Tfl Examples The structure of the present invention will be specifically explained below with reference to Examples.

Processing of ill filler (1-1) 25,000 g of iron powder made by the atomization method (K I P2O3, manufactured by Kawasaki Steel Corporation, specific gravity 7.85) was mixed at low speed in a high-speed mixer (@Super mixer manufactured by Kawata). , 125 g of silane coupling agent (125 g of KBE903 manufactured by Shin-Etsu Chemical Co., Ltd. diluted 5 times with denatured alcohol/water = 9/1 melt) was added, and then 7
Mixing was continued for 30 minutes at 5017 m to volatilize the alcohol content and produce treated iron powder.

(1-2> Ferrite powder (DB850 manufactured by Toda Kogyo Co., Ltd.,
While mixing 25,000 g of silane coupling agent (KBE, manufactured by Shin-Etsu Chemical Co., Ltd.) at low speed in a high-speed mixer (@ Super mixer manufactured by Kawata),
903125g in denatured alcohol/water = 9/l solution
(diluted twice) was added, and mixing was continued for 30 minutes at 75,017 m to volatilize the alcohol content to produce treated ferrite.

(2) Composition The above-mentioned treated iron powder, treated Ferrai 1-16-nylon powder (1011F manufactured by Ube Industries, Ltd.), and methylene bisstearamide (Panloop N18P manufactured by Lunar Kasei Co., Ltd.) were weighed as shown in Table 1. and mixed for 5 minutes in a drum blender.

This mixture was molded by injection molding using a melt kneading mechanism described in Japanese Patent No. 1104727 (mold clamping force 100).
In step T), the mixture was supplied from a screw feeder interlocking with the screw so that the supply section in the cylinder of the molding machine was starved, and molding was performed.

The molded product is an ASTM D6384 type tensile test piece (thickness 3
．． Table 1 shows the molding results, tensile strength, and specific gravity (measured with the disks) using a set of disks with a diameter of 2 m*, a diameter of 59 mm, and a wall thickness of 3.2 fins.

In this way, the composition of the present invention makes it possible to use inexpensive atomized iron powder and to stably produce molded products with high specific gravity and excellent physical properties that could not be achieved with conventional technology. became.

(Notes to the table) (11) The blend separated and iron powder clogged the screw, causing it to stop rotating.

(2) Molding was possible, but there were large fluctuations in screw rotation. The surface smoothness of the molded product is poor.

(3) Due to insufficient screw rotation torque, the mixture was not plasticized and molding was impossible.

T41ASTM D648 Type 4 Cannot be measured because the tensile test piece is not completely filled.

Furthermore, this invention has also developed a method for efficiently molding molded articles such as flywheels from such high specific gravity compounds, and this invention has extremely large industrial effects.

(g1 Effects of the invention) This invention provides a high specific gravity plastic composition containing a high concentration of metal powder, in which inexpensive iron powder produced by the atomization method and flexible metal compound fine powder are blended in an appropriate ratio. This prevents separation of metal and resin powder mixtures, establishes complete uniform mixing and moldability of highly concentrated compositions that could not be achieved with conventional technology, and enables molded products with high specific gravity and excellent physical properties to be produced at low cost. We have succeeded in producing this product in a stable manner.

Claims (4)

[Claims] (1) The first component is iron powder with a particle size of 150 mμ or less made by the atomization method, and the second component is iron powder with a specific gravity of 3.
In the plastic composition filled with 85 to 92% by weight of a viscous metal powder or metal compound powder with a particle size of 10 mμ or less, the metal powder is highly concentrated filled with a second component of 4 to 15% by volume based on the total composition. plastic composition. (2) A method for producing the composition according to claim 1, which comprises molding the powder mixture using a screw in-line injection molding machine. (3) The method for producing a composition according to claim 2, wherein the injection molding machine is a molding machine equipped with a kneading mechanism described in Japanese Patent No. 1104727. (4) The composition according to claim 2, wherein the mixed material is supplied from a material supply device that operates in conjunction with the screw of the injection molding machine so that the feed section of the molding machine cylinder is starved. Production method.