JPS61179802A - Treatment of metallic powder - Google Patents

Abstract

PURPOSE:To obtain metallic powder having conductivity and good affinity to a synthetic resin by treating the metallic powder in an aq. amine soln. and coating the powder with a titanate coupling agent after drying. CONSTITUTION:The metallic powder such as copper powder is immersed into the aq. soln. prepd. by dissolving >=1 kinds of amines such as triethanol amine and the deriv. thereof and is treated under stirring. The metallic powder is then dried and is mixed under stirring with the titanate coupling agent such as isopropyl triisostearoyl titanate by which the metallic powder is coated. The characteristics such as conductivity possessed by the metallic powder are improved and the affinity to the synthetic resin is improved by such surface treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for processing metal powder most suitable for filling a synthetic resin with metal powder to obtain a functional composite material.

To give examples of specific fields of use, synthetic resin molding materials filled with metal powder include high specific gravity materials, radiation shielding materials, bearing materials, pressure-sensitive switch materials, conductive materials, heat conductive materials, and wear-resistant materials1. etc.

Further, examples of synthetic resin paints containing metal powder include those having electrical conductivity, electromagnetic shielding properties, and abrasion resistance.

The metal powder treated according to the present invention has good affinity with synthetic resins and does not cause harmful chemical reactions with synthetic resins, so even when filled with a large amount of metal powder, the physical properties of synthetic resin composite materials are There is little deterioration, and there is no problem of oxidative deterioration of the synthetic resin due to metal powder. Furthermore, since properties unique to metals, such as electrical conductivity, are maintained, it becomes possible to develop composite materials with new functions.

[Conventional technology]

Metals and synthetic resins have poor affinity for each other, and there are problems of corrosion of metal powder and oxidative deterioration of synthetic resins due to metal powder, so various surface treatment methods and additives have been devised.

Conventional techniques include applying rust prevention to metal powder using organic inhibitors such as benzotriazole and tolyltriazole, but these protective coatings impair electrical conductivity and cannot be used in applications where electrical conductivity is desired. . To improve the affinity and dispersibility with synthetic resins, there is a method of adding thiol/S/triazine and its derivatives (for example, JP-A-53-45346), or a method of using a titanate coupling agent (for example, Japanese Unexamined Patent Publication No. 1983
-207651). However, although these methods have an improvement effect, they are insufficient and tend to impede the properties of the metal powder, so they cannot be said to be excellent methods for treating metal powder to be filled into synthetic resins.

[Problem that the invention seeks to solve]

In order to prevent corrosion of metal powder and oxidative deterioration of synthetic resin due to metal powder, some kind of rust prevention treatment is required. However, in conventional technology, protective coatings for rust prevention are often bonded through metal oxide films or are insulating (and cannot be used for conductive purposes. There is a need for a rust-preventing treatment method that does not impair properties.

On the other hand, silane-based, aldium-based, and titanate-based coupling agents are commercially available to improve the affinity between inorganic materials and synthetic resins. It is known that titanate-based compounds are effective, but no effective treatment method has been found for metal powder, and their effectiveness as coupling agents has not been fully utilized.

Therefore, the present inventors have developed a method for processing metal powder that maintains or improves the properties of metals such as conductivity even after surface treatment, does not cause harmful chemical reactions with synthetic resins, and has good affinity with synthetic resins. The present invention was completed as a result of various researches to find a method.

[Means to solve the problem]

That is, the present invention is characterized in that metal powder is treated with an aqueous solution in which at least one of amines and derivatives thereof is dissolved, then the metal powder is dried, and a titanate coupling agent is mixed and coated on the metal powder. This is a method for processing metal powder.

Metal powders include copper, iron, nickel, lead, tin, silver, and alloy powders thereof, but the method of the present invention is particularly applied to metal powders such as copper powder, copper alloy powder, iron powder, and nickel powder. This gives very good results.

The amine used in the method of the present invention is a compound in which the hydrogen atom of ammonia is replaced with a hydrocarbon residue 5R, and examples thereof include ethylamine, amylamine, cyamylamine, triethanolamine, arylylamine, and cyclohexylamine. Derivatives of amines include hydrochloride, sulfate and organic acid salts, but water-soluble a
Any compound can be used.

The amount of amine added to the metal powder varies depending on the amount of aqueous solution used, the processing method, and the particle size of the metal powder, but generally it is effective from 0.01% by weight to the metal powder being treated, and 10% or less is effective. desirable. As a treatment method, there are a method of spraying an aqueous solution, a method of stirring metal powder in an aqueous solution, a method of making a paste state with a small amount of an aqueous solution and moistening it.

The processing time may be short, and the processing time can be freely selected.

The titanate coupling agents used in the method of the present invention include, for example, isopropyl triisostearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl tris(dioctyl pyrophosphate) titanate, and tetraoctyl bis(ditridecyl phosphite) titanate. , bis(dioctylpyrophosphate)oxyacetate titanate, and the like.

The amount of titanate coupling agent added is metal powder.

It varies depending on the particle size and metal composition, but in general,
It is effective from 0.1% by weight to the metal powder to be treated, and preferably 10% or less.

The industrially preferred method for treating titanate coupling agents is to add them directly to metal powder and stir and mix with a mixer or ball mill. A method in which a titanate coupling agent is diluted in a highly compatible solvent such as toluene or methyl ethyl ketone and mixed with stirring is an effective method that can provide a uniform coating in a short time.

[Effect]

As for the reason why the treatment method of the present invention has excellent properties, it is not fully clear what kind of mechanism, what kind of bonding, or what kind of interaction occurs, but the following may be considered.

Treating metal powder with an aqueous solution of amine has the effect of cleaning the surface of the metal powder, and drying the treated metal powder generates a chemical compound on the surface of the metal powder, which has a certain degree of rust prevention effect. It will be done.

Furthermore, treating the metal powder in an aqueous solution and drying it means that hydroxyl groups are forcibly added to the surface of the metal powder, creating an optimal state for the titanate coupling agent to bond to the surface of the metal powder, resulting in excellent strength. , the effect of the pulling agent occurs. In other words, Ti, which is a transition metal in titanate coupling agents,
After the elements are sufficiently bonded to the metal surface, hydrophobic groups such as isostearic acid residues, octyl alcohol acid groups, and tridecyl alcohol residues of phosphite esters face outward to make the metal powder surface hydrophobic. Since these hydrophobic groups have a part that is compatible with the mechanism, it is thought that the affinity with synthetic resins is also improved.

Although it is thought that the mechanism is the same even if other coupling agents are used, the present inventors have found that silane-based coupling agents have drawbacks such as significantly poor conductivity and aluminum-based coupling agents have poor moisture resistance. This was discovered through research and a titanate-based coupling agent was used.

Although there is a method of adding water to metal powder to improve the coupling effect, there is a problem that the metal powder oxidizes during drying. Furthermore, if a coupling agent is added without drying, or if a coupling agent and water are added at the same time for treatment, there will be a large amount of residual moisture, which will cause various problems. In the treatment method of the present invention, the residual water content of the metal powder treated with an aqueous amine solution and dried was measured and found to be approximately 0.005 parts by weight. Although there are differences in water content depending on the type of metal powder, this amount is probably necessary and essential for the parent wood group of the titanate coupling agent to hydrolyze and bond to the metal. The improved conductivity of synthetic resin composite materials filled with metal powder is thought to be due to the synergistic effect of rust prevention and affinity.

〔Example〕

The present invention will be specifically explained below using Examples.

All parts in the text are parts by weight.

Example 1 100 parts of atomized copper powder having an average particle size of 50 μm was immersed in an aqueous solution prepared by dissolving 0.01 part of triethanolamine in 100 parts of water, and stirred for 1 minute. After that, the copper powder and water were separated using paper and dried by heating at 80° C. for 120 minutes in a hot air dryer. After drying, the mixture was left at room temperature for a while, and then 0.1 part of isopropyl triisostearoyl titanate, which is a titanate coupling agent, was dissolved in 2 parts of toluene and added to the copper powder.

The mixture was mixed using a mixer at 6 rpm for 10 minutes to coat the surface of the copper powder with the titanate coupling agent.

The copper powder treated in this manner had the color of metallic copper and was hydrophobic.

In order to examine the affinity and reactivity with synthetic resins, 75% by weight of the treated copper powder thus obtained was filled into polybutylene terephthalate resin, and a flywheel was molded using an injection molding machine.

Compared to molding using copper powder not treated according to the present invention, the moldability was very good, and the surface appearance was copper-colored without turning red. The physical properties and electrical properties of the molded product are shown in Table 1 as Comparative Example 1, which is filled with untreated copper powder.

Table 1 Example 2 100 parts of electrolytic copper powder having an average particle size of 2 μm was immersed in an aqueous solution prepared by dissolving 2 parts of triethanolamine in 100 parts of water, and mixed and stirred for 60 minutes. After that, the copper powder and water were separated using paper and dried by heating at 80° C. for 120 minutes in a hot air dryer.

After drying and leaving it for a while at room temperature, 5 parts of bis(dioctylpyrophosphate) oxyacetate titanate, which is a titanate coupling agent, was added to the copper powder and mixed with a mixer at 6 rpm for 60 minutes to coat the surface of the copper powder with the titanate coupling agent. coated.

The copper powder treated in this manner had the color of metallic copper and was hydrophobic, and did not change color even when immersed in water for 30 days, although the untreated copper powder turned blackish.

In order to examine the affinity, reactivity, and electrical conductivity with the synthetic resin, the treated copper powder thus obtained was 80% by weight based on the solid content of the acrylic resin. A conductive paint was prepared by diluting with toluene.

The coating film obtained with this conductive paint has a less rough appearance than that produced using untreated copper powder, and
No copper powder fell off from the paint film, and gelation did not occur even if the paint was left for a long time.

The electrical performance of the coating film filled with untreated copper powder is shown in Table 2 as Comparative Example 2. The coating film thickness was 50 microns.

Table 2 Example 3 Add 1 part of cyclohexylamine carboxylate to 100 parts of water.
The dissolved aqueous solution was sprayed onto crushed iron powder having an average particle size of 5 μm, and the iron powder was immediately separated from water and dried in a vacuum dryer for 180 minutes. Then, 10 parts of tetraoctyl bis(ditridecyl phosphite) titanate, which is a titanate-based coupling agent, was added, and 3 parts were added using a ball mill.
Orpm Mixed for 30 minutes.

The iron powder treated in this way has hydrophobicity, and was able to prevent rusting even in salt water where untreated iron powder would oxidize.

4 by weight on ABS resin to check its affinity with synthetic resins.
As a result of measuring the Izotsu impact strength (in inches) of the injection molded plate filled with 0%, the one filled with untreated iron powder was 2.
．． The weight was 3 kg, cm/cm, but the one filled with the treated iron powder of Example 3 of the present invention had a weight of 5 kg, cm/cm, more than double the value, and was sufficiently usable.

Example 4 An aqueous solution prepared by dissolving 0.5 parts of amylamine in 10 parts of water was added to 100 parts of nickel powder having an average particle size of 5 μm, and the mixture was mixed and stirred using a mixer at 6 Orpm for 30 minutes. Thereafter, it was dried by heating at 120° C. for 180 minutes in a hot air dryer. After drying and leaving it at room temperature for a while, 3 parts of isopropyl tridodecylbenzenesulfonyl titanate, which is a titanate coupling agent, was added to the Nisogal and mixed at 5 Qrpm with a mixer.
The mixture was mixed for 60 minutes to coat the surface of the nickel powder with the titanate coupling agent.

In order to examine the affinity and electrical conductivity of the nickel powder thus treated, it was filled in an epoxy resin at 80% by weight.

As a result, it is easy to disperse uniformly, and the electrical conductivity when charging untreated nickel powder is 10-1Ω.
·cm, but when filled with the treated nickel powder of Example 4 of the present invention, a volume resistivity of 10-''Ω·cm was obtained.

〔Effect of the invention〕

As explained in detail above, the treatment method of the present invention improves the properties of metal powder such as conductivity even after surface treatment, does not cause harmful chemical reactions with synthetic resins, and has good compatibility with synthetic resins. This has the effect of greatly improving the

Therefore, it has become possible to obtain a new metal powder-containing synthetic resin composite material that takes advantage of the characteristics of metal.

Claims (1)

[Claims] A method for treating metal powder, which comprises treating metal powder with an aqueous solution containing at least one of amines and derivatives thereof, then drying the metal powder, and coating the metal powder with a titanate coupling agent. .