JPS6096548A - Electrically conductive material - Google Patents

Abstract

PURPOSE:To provide an electrically conductive material capable of imparting a synthetic resin, paint, adhesive, etc. with excellent electrical conductivity, by applying a metallic film to the surface of a hollow glass particle by electroless plating, thereby forming a uniform and tough film to each particle. CONSTITUTION:Hollow glass particles having an apparent specific gravity of <=1, an average particle diameter of preferably <=100mu (the finer, the better) and a sharp particle size distribution, i.e. so-called glass balloons, are sensitized by contacting with an aqueous solution of a soluble stannous compound e.g. by immersion or spraying, and then brought into contact with an aqueous solution of a soluble Pd salt in the same manner to effect the activation of the particle. The particles are dispersed in an queous medium, and an electroless plating liquid is added to the dispersion at a controlled rate of addition to effect a rapid plating reaction. A unifrom and tough metallic film is formed to the surface of the dispersed particle by this process. The thickness of the metallic film can be controlled by adjusting the amount of the plating liquid. Since the apparent specific gravity of the obtained particle is 0.4-2.0, the product can be used as an additive to impart high electrical conductivity to a synthetic resin, paint, adhesive, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a conductive material formed by applying an electroless plating film to particles.

Recently, the need for magnetic shields has increased, and the use of conductive materials for tX radiation has become very popular.

Conventionally, typical 1j conductive materials include nickel, copper,
Metal powders such as silver or alloys are known, and these are used, for example, by adding them to base materials such as synthetic resins, paints, or adhesives to impart their respective electrical conductivity.

However, since such metal powder has a high specific gravity,
Not only may there be a lack of uniformity with the base material when compounding, molding, or painting synthetic resins and paints, but also
Workability also becomes difficult. In particular, if the amount added is increased in the hope of improving conductivity, the above-mentioned problems will gradually come to the fore, and this will also lead to an increase in the weight of the product.

On the other hand, due to advances in technology and development of applications, electroless plating technology is now applied regardless of the material, organic or inorganic, and regardless of its shape or size. However, in many cases, the base material is plate-shaped or molded,
The development of applications for powdered or granular core materials is recent, and since they are new, there is no established manufacturing method.
At present, it is processed only slightly according to conventional general methods.

That is, in the case of electroless plating, a method is usually used in which the substrate to be plated is immersed in a plating solution prepared in advance, and the reaction is stopped after a predetermined time period is allowed to react.

The same method as above is also used when the plating base material is powder or granular material, but in this case, it is added to the plating solution immediately and plated, and after the reaction, the plating solution is subjected to IP filtration, rapid cooling, dilution, etc. A stop must be made.

When the base material is a powder or granular material, the plating reaction rate is extremely fast because the specific surface area is significantly larger than that of other base materials.

Therefore, the pH of the plating solution and the concentration of each component fluctuate dramatically, so adjust the pH carefully! It is not only extremely difficult to maintain the plating solution stably by replenishing 111 and each component, but also the plating speed changes each time.On the other hand, there is no problem if the powder and granules can be added to the plating solution all at once. If the plating film is added over a long period of time, there will be a difference in the thickness of the plating film at the beginning and end of the plating process, resulting in non-uniformity.

Particularly when plating powder or granules, a problem is that when a plating film is applied to agglomerated secondary particles, it breaks during use, exposing the uncoated surface and causing defects such as pus and pus.

Therefore, when plating powder or granular materials, it is most important to apply a plating film to a material that is sufficiently dispersed with as few secondary particles as possible, but this cannot be expected at all with conventional methods. Ta.

The non-inventors conducted intensive research based on the facts on paper, and found that
The present invention was completed by developing a technique for effectively applying electroless plating to hollow glass particles.

That is, the present invention is a conductive material formed by providing an electroless plating film on the surface of fine medium-sized glass particles.

In the present invention, the base material for electroless plating is hollow glass particles, so-called glass balloons, and the average particle size is io
It is preferable that the particles be as fine as possible and have a uniform particle size distribution, with an apparent specific gravity of 7 or less.

As long as the hollow glass particles as described above are used, the composition of the glass can be applied without particular limitation.

The conductive material according to the present invention is a material in which an electroless plating film is uniformly applied on the surface of the hollow glass fine particles as described above, and the plating film is not particularly limited, but representative examples may be used. is a plating film of nickel, copper, silver, gold, or an alloy containing at least one of them.

The thickness of the plating film is not particularly limited as it changes depending on the particle size of the hollow glass particles of the base material or the type or purpose of the plating film, but from the viewpoint of conductivity, the coverage of the plating film is at least 20%, preferably 3
0% or more is suitable. Although this upper limit is naturally limited solely from an economic standpoint, the apparent weight is at most 2.
．． 0, and can be limited from this point.

In the present invention, the coverage of the plating film refers to the value given by the following formula.

−W0 0 =+ −X /θO [In the formula, 0: coverage rate, W: weight of plated product, Wo: weight of hollow glass particle base material] The conductive material according to the present invention has the above-mentioned electroless plating film. Any manufacturing method may be used as long as it can be applied, but the preferred manufacturing method is as follows.First, in order to perform electroless plating coating treatment, it is necessary to perform pretreatment, which can be done using a known method. However, there is no particular difference in the present invention. That is, this pretreatment involves sensitization treatment and activation treatment, but it is preferable to carry out the process after performing alkaline cleaning or etching treatment if necessary. The usual method is to bring the material into contact with the material by immersion or spraying, and then to carry out the activation treatment by bringing the material into contact with a soluble palladium salt aqueous solution in the same manner.

Next, an aqueous suspension is prepared for electroless plating on the surface of the pretreated fine hollow glass particles.

The aqueous suspension herein refers not only to cases where the medium is water, but also to cases where a thin electroless plating solution that does not substantially cause electroless plating or an aging plating solution is used. . The aqueous suspension should be dispersed as uniformly as possible.
It is important to prepare the particles in such a state that substantially no agglomerates are present. Of course, these hollow glass particles have good dispersibility, and the desired stirring operation is sufficient;
Ultrasonic dispersion or other dispersion means can be used as long as the hollow particles are not destroyed. When dispersing the core material, a dispersant such as a caustic alkali, an alkali such as sodium silicate, an alkali polyphosphate, or a surfactant may be used as necessary. There is no particular reason to limit the concentration of the aqueous suspension, but if the slurry concentration is low, the plating solution concentration will decrease and each processing step will be required, which is not economical.
On the other hand, if the concentration becomes high, the dispersibility of the core material deteriorates, so the slurry concentration may be appropriately set to a desired value depending on the physical properties of the core material. In addition, when plating the core material in this suspension, it is desirable to adjust the temperature of the suspension to a plating temperature in advance so that plating can be carried out effectively. Electroless plating solution is added to the suspension in a controlled manner. It is desirable that the suspension be subjected to stirring, ultrasonic dispersion treatment, etc. as necessary to maintain the dispersed state, and it is also desirable that the temperature be set so as to be controllable. The t%-free plating solution is added to an aqueous suspension and diluted depending on the volume, unlike plating operations in which the substrate to be plated is immersed in a bath of the plating solution. , it is better that the concentration of the plating solution be higher than that of the energized plating solution.

The reason why the electroless plating solution is added in a controlled manner is that the addition speed as well as the plating solution concentration directly affect the plating reaction, and these factors are also significantly related to the physical properties, particularly the surface properties, of the core material. This means that the rate of addition of the plating solution should be determined in order to form a uniform and strong plating film without causing uneven plating, taking into full consideration these factors, and in many cases it is better to add the plating solution gradually. Good. On the other hand, along with this addition of the plating solution, it is often desirable to separately and simultaneously add an alkaline agent, if necessary to adjust the pH of the aqueous suspension. The reason for this is that as the plating reaction progresses with the addition of the plating solution and the reducing agent such as sodium hypophosphite in the solution is oxidized, the hydrogen ion concentration increases and the pH of the aqueous suspension gradually decreases. Therefore, in order to maintain the initially set pH constant,
Metsu? It is preferable to add the liquid and the pH adjuster ♂ simultaneously as described above. As for the addition method, it may be added while controlling the pH meter, but it may also be added at a predetermined concentration of firefly alkaline waves that are suitable for the oxidation-reduction reaction of the reducing agent.

In this way, by controlling and adding the electroless plating solution to the aqueous suspension, a rapid plating reaction occurs in the suspension, forming a uniform and hard plating film on the surface of the dispersed particles. Therefore, the thickness of the plating film can be adjusted depending on the amount added, and the amount added is set depending on the application. That is, by following the method of the present invention, the coverage rate of the plating film can be freely set and achieved with high precision.

The plating film applied to the hollow glass particles is as described above, but the liquid composition of these electroless plating solutions is not particularly limited, and in most cases, known ones are sufficient.

The plated product obtained in this way has a uniform and strong film applied to each particle, and has an apparent specific gravity of O, D to D.
Since it is within the range of C and θ, it can be added as a conductive material to synthetic resins, paints, adhesives, etc. to impart excellent conductivity.

Therefore, if we compare the concentrated acidic material according to the present invention with conventional metal powders, we will find that, for example, 1) the amount of substances used can be significantly reduced; When added, it has significant advantages such as eliminating uneven distribution due to differences in specific gravity, and when added to synthetic resins, it is easy to process the resin and a homogeneous product can be obtained, and its uses are promising. The present invention will be explained below based on Examples.

Example 1 Hollow glass particles with an average particle size of 32 μm (trade name Phyllite-〇〇= Nippon Phyllite■
iooi (manufactured by Co., Ltd.) was added to an aqueous solution of stannous fluoride/Il and stirred at room temperature for 30 minutes. Then, the mixture was filtered and washed for sensitization treatment. Then chloride/<9 silaA o,t
Ill s The above-mentioned treated product was added to an aqueous solution it containing hydrochloric acid o -t WLt/L, stirred at room temperature for 70 minutes to perform activation treatment, and then filtered and washed to perform pretreatment. 0 Pretreatment completed. The sample was added to demineralized water heated to 6S°C/1, stirred thoroughly, and then mixed with an electroless nickel plating solution (nickel sulfate: / g 01/l s, sodium hypophosphite: 2/g 11/Ls). Ethylenediamine: ,y
o 9/l% pH: t, 0) eighty t and caustic soda 96. & l/L water solution gzogo respectively som
1 minute and 2! I; O was added to the above aqueous suspension at a rate of tnl/min, and stirring was continued while keeping the temperature at 65°C until the generation of hydrogen stopped after the addition. Thus, the coverage rate was 2 qO%.
, an electrically conductive material consisting of hollow glass particles with an apparent specific gravity of 7 and a uniform and strong film of IO was obtained. Glass particles (trade name: Sankirai, manufactured by YO Koni Sanki Kogyo ■) 1001 were pretreated in the same manner as in Example 1, and the pretreated sample was added to demineralized water/l heated to 7S°C. After thorough stirring, an electroless nickel plating solution and a caustic soda solution having the same composition as in Example 1 were added to the above aqueous suspension at a rate of 5 oyd/min, td/min, respectively, After the addition was completed, stirring was continued while keeping the temperature at 7J°C until the generation of hydrogen stopped.Thus, a uniform and strong film was formed with a coverage ratio of 5oNs and an apparent specific gravity of 1.97. Example 3 Hollow glass particles with apparent specific gravity O, col, and average particle size of 63 μm (product name Q, -0BL: manufactured by Asahi Glass Company) ioo g
was pretreated in the same manner as in Example/.

After adding the pretreated sample to demineralized water/l heated to 60°C and stirring thoroughly, electroless copper plating solution (ft acid copper:
! ;011/ls formalin (37 ftN)
: / o oynl/1%I! IDTA: Cool/
l, dipyridyl: /1rVt1 carini cyanide 0.
2 Add i/Ls caustic soda to adjust pH/co, O)
A', A A and an aqueous solution LJ t of caustic soda & iJ Ill respectively to o ml 1 min and kOr
It was added to the above aqueous suspension at a rate of d1 min, and stirring was continued while keeping the temperature at θ°C until hydrogen generation stopped after the addition was completed.

Kaj < shi, coverage rate: S2%, apparent specific gravity 20, Qλ7
A conductive material made of hollow glass particles was obtained, which formed a uniform and strong film.

Example 1: Specific gravity: 0.70, average particle size: S μm
The same hollow glass particles/3011 were treated in the same manner as in Example/611, and further electroless steel plating was performed in the same manner as in Example 3. However, the amounts of electroless steel plating solution and caustic soda aqueous solution used were as follows: ,OL, /,,tA. Next, the copper-coated particles were filtered and washed, and then electroless silver plating solution (silver cyanide soda: 9.1 Ills cyanide soda: Il, ?I/As hydrogenation base 1): s
, u Ill s caustic soda: 1611/1) 4'
The zero plating solution introduced into L was heated to 70° C. while stirring, and this condition was maintained until hydrogen generation stopped.

The appearance is hollow glass with a specific gravity of 4I. The lower layer has a coating rate of 5% copper, and the upper layer has a coating rate of 39% silver with a uniform and strong coating. A conductive material consisting of particles was obtained. In Example 5, the same hollow glass particles as in Example 1 with an apparent specific gravity of 0.70 and an average particle diameter of S μm were pretreated and treated with electroless copper in the same manner as in Example D. After plating, electroless gold plating solution (gold cyanide 9.tIllL) was applied.

Carini cyanide 4. ! r 9/Lz potassium hydride: s, tty/l, caustic carinyl/, cog7t)
Put q inside. The plating solution was heated to 80° C. while stirring, and this condition was maintained until hydrogen generation stopped.

Thus, the apparent specific gravity: 1. The lower layer of Da 3 has a coating rate of copper with a coating rate of Hiroyu and S9, and the coating rate on the lower layer of 3 is a coating of hollow glass particles formed with a uniform and strong coating of gold with a coating rate of 0.0, g%. I got it.

Patent acquisition Nippon Kago Kogyo Co., Ltd.

Claims (1)

[Claims] 1. A conductive material formed by providing an electroless plating film on the surface of fine hollow glass particles. The first claim whose apparent specific gravity is less than or equal to
Conductive materials as described in section. 3. The conductive material according to claim 1, wherein the electroless plating film is selected from nickel, copper, silver, or gold/JJI or one or more plating films.