JPH01162868A - Electroless plating of alumina ceramic fiber - Google Patents

Abstract

PURPOSE: To obtain alumina ceramic fibers, with industrially advantage, that can be readily and uniformly plated deeply inward, while they are collected, and are suitably useful in composite materials with resins by setting the bulk density to a specific value after pretreatment and dipping the treated fibers in a plating bath. CONSTITUTION: (A) Alumina ceramic fibers, prepared by melt-extrusion method, preferably having the thickness of from several microns to several tens microns, are etched with, for example, an aqueous hydrofluoric acid solution, then sensitized by an aqueous stannous chloride solution, then activated with a palladium chloride aqueous solution, further catalyzed and accelerated and are subjected to other plating pre-treatments. Finally, the ceramic fibers are made as a fiber block whose bulk density is adjusted to 0.01-1 g/cm<3> , and (B) the resultant ceramic fibers are dipped or soaked in an electroless plating solution of copper, nickel or the like whereby the objective fibers are obtained.

Description

Detailed Description of the Invention (a) Object of the Invention (Field of Industrial Application) The present invention relates to an electroless plating method for alumina ceramic fibers, and more specifically, for electroless plating of alumina ceramic fibers, particularly short fibers thereof, in a collected state. This invention relates to a method for uniform electroless plating that is simple and industrially advantageous.

(Prior Art) Alumina ceramic fibers are produced by various methods, but in the case of short fibers, one is usually "bulk".

Or apply needling to the bulk and fc "planta."

It is supplied in a collected state called ``gold''.

Furthermore, the fibers in the collected state are used as raw materials to process the fibers into aggregates such as dates and felt.

Friend, alumina ceramic fiber is copper.

When plated with nickel, cobalt, silver, etc., the wettability with the metal is improved when the material is composited with metal, and the strength and durability of the resulting composite material is improved.

Or, in order to impart conductivity, a composite material with resin may be
It can be conveniently used as an electromagnetic shielding material, and since it has thermal conductivity, it has excellent heat dissipation effects, etc. fc1
! It can provide excellent performance such as being able to be used as a child material base material substrate. For this reason, it is desired to develop a technique for simply and industrially advantageous plating on alumina ceramic fibers.

However, conventionally, electroless plating for alumina-based ceramics has been performed on complete plate-shaped products of alumina-based ceramics or long fiber-like alumina-based ceramics.

However, a method was known in which this method was applied to fiber bundles.

Electroless plating of collected alumina ceramic fibers has not been considered at all in the past, as it is thought that even the inner fibers cannot be plated uniformly.

(Problems to be Solved by the Invention) The present invention seeks to provide an industrially advantageous method for electroless plating of alumina ceramic fibers.

(b) Bottom of the Invention (Means for Solving the Problems) As a result of repeated research in order to solve the above-mentioned problems, the present inventors have discovered that alumina-based ceramic fibers in a collected state have been developed. However, if a collected state with an appropriate bulk density is selected, the plating solution can sufficiently penetrate (penetrate) into the inside of the collected fibers due to the bubbling effect of hydrogen gas generated in the electroless plating reaction. The present invention has been achieved based on the present invention, which is extremely advantageous industrially since it is possible to uniformly plate even the inner fibers, and this method can directly plate the collected fibers.

In other words, in the electroless plating method for alumina ceramic fibers of the present invention, alumina ceramic fibers that have been subjected to necessary plating pretreatment are placed in a collected state with a bulk density of 0.01 to IN/33 at the liquid level of an electroless plating bath. 'ff: This is a method characterized by plating while being immersed and held under the bubbling effect of hydrogen gas generated in an electroless plating reaction.

The alumina-based ceramic fiber to which the electroless plating method of the present invention is applied can be manufactured by any method. Known methods for producing alumina-based ceramic FFL fibers include, for example, a melt fiberization method and a precursor fiberization method.

It may be manufactured by any manufacturing method.

Well, the alumina-based ceramic fibers may be fR fibers that contain a large amount of alumina (e.g., 45 wt. Alumina-based ceramic fibers are advantageously used.

The bulk density after the necessary plating pretreatment is 0.01 to 1.
．． When one piece of alumina ceramic fiber in a 9/♂ collected state is immersed and held under the liquid level of an electroless plating bath according to the method of the present invention, hydrogen gas is generated by the electroless plating reaction, and the fiber is Surprisingly, the plating bath solution sufficiently penetrates (penetrates) the collected fibers to expose them to the bubbling effect of generated hydrogen. It can be easily and evenly plated. If the hydrogen bubbling effect generated in this case is severe, some of the fibers will float to the surface of the plating bath. It becomes a hindrance. In such cases, use measures such as installing an excessive mesh jig near the liquid surface of the plated oak to prevent even a portion of the fibers from floating above the liquid surface, and to keep the fibers always under the liquid surface. Plating is carried out while immersed in and held.

The plating method of the present invention is a method in which the fibers in the collected state can be plated in the collected state, so not only can the plating process be performed in the entire collected state, but also the pre-plating treatment can be carried out. The entire plating process, including post-plating treatments such as rinsing and drying, can be carried out in the collected state, which makes plating aluminum-based ceramic fibers extremely advantageous industrially. can be done.

In the plating method of the present invention, as described above.

Bulk density is 0.01-1 g/tyl, preferably 0
．． 01 to 0.59/- fibers in a collected state are used.

This is because if the bulk I # degree is too strong, it will be difficult for the plating bath solution to fully penetrate into the fibers inside the collected cotton, and if the bulk density is too small, it will be uniform. However, it is advantageous for the plating itself.

Plating productivity is decreasing, which is industrially disadvantageous.
It is from.

In general, the supply form of alumina ceramic fibers in the market can be roughly divided into fibers that are simply collected using a blowing method, etc., which is called "bulk" and has a bulk density of 0.01 to 0.19/3. material, and the bulk of such bulk material after needle milling treatment is 0.08 to 0.211/
This is called the "blanket" of cIn3. Furthermore, once these bulk or blanket-like fibers are used as raw materials.

Processed into felt with a density of 0.21/cm, or into a date with a bulk density of 0.15 to 1 g/am5, and as a raw material for composite materials with resins and metals.

Pieces cut into small chip-like pieces are also available.

These fibers are supplied on the market in the form of bulk, blankets, felts, and cords.

Their bulk densities are all 0.01~1! i'/c
Since it is within the range of m3, it is suitable for use as a fiber to which the plating method of the present invention is applied. However, when cutting out small chip-like pieces from these aggregates, it is difficult to immerse and hold the chip-like pieces in the plating bath solution, and it is also troublesome to transfer the fibers after plating to the washing process. Therefore, it is not preferable as a raw material fiber when the plating method of the present invention is carried out industrially. When plated chip-like pieces of alumina-based ceramic fibers are required, the pieces in the form of bulk, blanket, felt, or board are plated using the plating method of the present invention, and then the plated bulk, etc. What is necessary is to cut out small chip-like pieces.

There is no particular restriction on the type of metal to be plated on the fibers according to the plating method of the present invention. plating method can be applied. As the deplating bath (liquid) for various metals used in that case, those conventionally used as electroless plating baths for those metals can be used as they are. Examples of main electroless plating bath compositions for these metals include the following.

■Copper plating example 1 Sulfuric acid steel 711/1 Potassium sodium tartrate 7511/1 Triethanolamine 101d#! Formalin (37%) 2
5 go/l Sodium hydroxide 201//1 Sodium carbonate lo i/1 Sodium cyanide 0
．． 1251/1 Example 2 Nitric acid steel 15 &/1 Sodium hydrogen carbonate l Oi/1 Potassium sodium tartrate 3
011/1 Sodium hydroxide 201//1 Formalin (37 required) 1007d#! ■Nickel plating example 1 Nickel chloride 241/1 Sodium hypophosphite 201/1 Sodium citrate 6011/1 Oxalic acid
401/1 Example 2 Nickel chloride 301/1 Sodium hypophosphite 101/11 Sodium citrate 101/1 ■Cobalt plated cobalt sulfate 0.07 moVl (20
g/l) Sodium hypophosphite 0.16moV'
1C171/13) Sodium citrate 0.15
molAC451/l) ■ Gold-plated potassium gold cyanide 2 g/l Ammonium chloride 7511/1 Sodium citrate 50
1/1 Sodium hypophosphite 10 t//1 Furthermore, as a plating preliminary treatment in the electroless plating method for this type of alumina ceramic, etc., for example, an etching process (activation process) in which the plate is immersed in a hydrofluoric acid aqueous solution. , a sensitizing step (reducing agent adsorption step for reducing and precipitating the catalyst metal in the next step; for example, an immersion step in a stannous chloride water bath solution), and an actipating step (
A process in which a metal with catalytic ability is reduced and deposited on the surface. For example, a process of immersion in an aqueous solution of palladium chloride), a catalyzing process (a process of adsorbing the catalytic metal), and an accelerating process (a process of activating the catalytic metal; for example, a process of immersing in an appropriate acid or alkaline aqueous solution)
There are various types of electroless plating pretreatments, such as, but the alumina ceramic fibers to which the electroless plating method of the present invention is applied are those that have been subjected to the necessary pretreatments as such plating pretreatments. Of course.

The fibers plated according to the plating method of the present invention are finished into plated fibers through processes such as washing and drying according to conventional methods.

(Example) An example 1) of the present invention will be described below, but the present invention is not limited to this example.

Example 1 0.2 g of collected alumina-based ceramic fibers with a bulk density of 0.05.9/♂, with an alumina content of 80% by weight and a silica content in the remainder, were sequentially treated in the following steps. Electroless plating was performed. Note that a water washing step was interposed between each step.

(2) Etching process The fibers were immersed for 2 minutes in 7-hydrofluoric acid, which was prepared by diluting 46 parts by weight of hydrofluoric acid with 2 times the volume of water.

■Sensitizing process Stannous chloride (SnC12-2H20) t-59/l
, and hydrochloric acid (hydrogen chloride content 35% by weight) at 511/l
The fibers treated in step (1) were immersed in the aqueous solution containing the fibers at room temperature for 2 minutes.

■Actipainting process Chloride! Radium (PdC12/2H20) All 0135
9/l.

and hydrochloric acid (hydrogen chloride content 35% by weight) at 15.9/l
The fibers treated in step (1) were immersed in the aqueous solution containing the fibers at room temperature for 2 minutes.

■Electroless nickel plating process Hypophosphorous acid (Hypophosphorous acid)) The FC fabric was treated in the process of The fibers were immersed at 70° C. for 15 minutes to undergo plating treatment. In this case, the fibers float due to the bubbling effect of the hydrogen gas generated, so a resin mesh jig installed near the liquid surface of the plating bath suppresses this floating and keeps the fibers constantly immersed and kept below the liquid surface. I let it happen. During the treatment period, the fibers were subjected to the bubbling effect of generated hydrogen.

■Finishing treatment After the plating treatment in ■, the fibers were washed with water and dried. When the -S of the obtained fiber was examined by cross-sectional observation of the fiber, it was found that all parts of the fiber were uniformly covered with a nickel plating layer with a thickness of 3 μm.

(c) Effects of the Invention The plating method of the present invention can plate alumina-based ceramic fibers while they are in a collected state, so that the plating method can be industrially advantageous.

Patent applicant: Mitsubishi Chemical Industries, Ltd. Evening 0.1 Attorney Patent Attorney Tsuchichutanimori Omote i・-1・ 1 (J゛・　1

Claims (1)

[Claims] 1) Alumina-based ceramic fibers that have been subjected to the necessary plating pretreatment in advance are immersed and held under the liquid surface of an electroless plating bath in a collected state with a bulk density of 0.01 to 1 g/cm^3, and the electroless plating reaction is performed. An electroless plating method for alumina ceramic fibers, which is characterized by plating while being subjected to the bubbling effect of hydrogen gas generated by.