JPH02277779A - Method for coating surface of synthetic resin structure with metal - Google Patents

Abstract

PURPOSE:To form a tightly adhered coating film of a metal on a surface to be plated by sticking a compd. contg. a metal acting as a catalyst for decomposition of peroxide to the surface to be plated, bringing the surface into contact with inorg. peroxide and carrying out electroless plating. CONSTITUTION:A compd. contg. a metal (e.g. copper, iron or zinc) acting as a catalyst for decomposition of peroxide, e.g. copper sulfate or iron nitrate is stuck to a base material and this base material is brought into contact with inorg. peroxide to violently decompose the peroxide by the catalytic action of the stuck compd. Nascent oxygen is generated by the decomposition and superfine ruggedness is imparted to the surface of the base material by oxidative decomposition with the oxygen to activate the surface to electroless plating. Since a catalyst for chemical plating is satisfactorily adsorbed on the activated surface, a coating film of a metal having superior uniformity and adhesion is formed on the surface by electroless plating.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of metal coating the surface of a synthetic resin structure,
More specifically, when forming a metal coating on the surface of a synthetic resin structure by electroless plating, the surface to be plated is treated with an inorganic peroxide prior to electroless plating to ensure uniformity and excellent adhesion. The present invention relates to a method for forming a metal coating.

Generally, in order to perform electroless plating on the surface of a non-conductive structure, it is common to immerse the non-conductive structure, which has undergone pre-treatments such as degreasing, catalysis, and activation, in an electroless plating bath. At that time, mechanical etching, chemical etching, or low-temperature plasma etching is used to improve the wetting of the substrate surface and improve the adsorption and adhesion ability of the catalyst, or to improve the adhesion between the substrate and metal. Surface treatments such as etching are also often used together.

Currently, synthetic resins that are industrially targeted for electroless plating include ABS resins, polypropylene resins, polyamide resins, polycarbonate resins, and the like. This is because these base materials are easily chemically etched and have relatively good adhesion during electroless plating.

On the other hand, examples of resins that are difficult to plate include polyester resins, vinyl chloride resins, vinylidene chloride resins, and the like.

Regarding chemical etching of these resins, for example, Japanese Patent Publication No. 47-19600 describes that prior to plating resins such as polyamide, polyester, polyvinyl chloride, polyvinylidene chloride, and polyolefin, an organic solvent suitable for each resin is used. For example, for vinyl chloride resins, use ethyl acetate, acetone, benzene, trichlene, etc., for polyester resins, use m-cresol, a 10-20% aqueous solution of 0-phenol, and for polypropylene, use Mix 10 to 20% of an organic solvent such as decalin or tetralin to a 5% aqueous solution of caustic soda, and further add 2 to 10 gzQ of a surfactant to form an emulsion. Swelling treatment is performed at 50 to 60°C in a bath or the like, and then,
2-5 gI of potassium dichromate in 50-60% sulfuric acid aqueous solution
A method is disclosed in which etching is performed for 1 to 2 minutes at 50 to 70 DEG C. in a bath containing Q, followed by electroless plating.

However, the chemical etching agent used after swelling the resin with this method, a mixture of sulfuric acid and potassium dichromate, has strong oxidizing power, which can cause problems such as resin defects and a decrease in physical strength. This may occur.

Moreover, wastewater containing dissolved chromic acid is subject to strict pollution regulations, and the wastewater treatment method is complicated, and furthermore, there are many difficulties in the treatment of chromium-containing sludge that has been collected by precipitation.

On the other hand, one way to improve the adhesion of electroless plated metal films is to add fine irregularities to the surface of synthetic resin structures, but sandblasting, which is often used on plastic molded products, etc. The mechanical roughening method causes severe damage to structures such as fibers, making them practically unusable.

In addition, JP-A-60-181362 discloses an improved method for chemically plating polyester fibers, in which polyester fibers containing a compound having a sulfonic acid group and/or a metal sulfonate group are immersed and/or passed through an alkaline bath. By doing so, a weight loss treatment of 8 to 30% by weight is performed,
A method is disclosed in which a metal sulfonate group is exposed on the fiber surface, and then a catalyst is applied and an activation treatment is performed to form an electroless plated metal film. However, in this method, in order to perform melt spinning with a compound having a metal sulfonate group coexisting in the polyester spinning raw material, special preparation is required from the spinning raw material stage. However, there are disadvantages such as abrasion of the spinning nozzle or yarn breakage during spinning.

Furthermore, JP-A No. 48-54299 describes a method for electroless plating of polyamide fibers, and this method includes the following steps:
An alcohol solution of N-alkoxymethyl nylon is attached to nylon fibers without physically or chemically etching the polyamide fibers, and then rapidly dried at a temperature higher than the boiling point of the alcohol as a solvent,
In this method, the alcohol quickly vaporizes during drying, forms fine bubbles, and separates from the surface of the N-alkoxymethyl nylon, thereby firmly adhering the N-alkoxymethyl nylon to the nylon fibers. The surface of N-alkoxymethyl nylon becomes finely uneven due to vaporization and dissipation of alcohol, so there is no need for chemical etching with a mixture of dichromic acid and sulfuric acid, and a metal plating layer is formed by direct electroless plating. It becomes possible to do so.

However, this method requires the use of alcohol as a solvent for N-alkoxymethyl nylon, and also requires a step of rapidly heating and vaporizing it above the boiling point of the alcohol, which poses a risk of fire and an environmentally friendly environment due to organic solvents. It has drawbacks such as pollution.

Furthermore, according to Japanese Patent Publication No. 63-35751, at least one surface of a fiber base fabric is treated with low-temperature plasma, and then ion blasting is applied to the treated surface to form a metal film on the surface of the fiber base fabric. A method is disclosed in which the low temperature plasma treatment is carried out at 0.01"l
Under the extremely low pressure of OTorr, using a gas that does not have plasma polymerizability, such as helium, neon, argon, nitrogen, oxygen, etc., these gases are dissociated and ionized by high voltage to create a sputtering effect on the surface of the fiber base fabric. It is described that the fiber surface is modified by the high energy of plasma, and its affinity with metal is improved, and a metal film that adheres tightly is formed by ion blasting. However, the above-mentioned low-temperature plasma processing equipment is expensive, and since the atoms dissociated and ionized by high voltage travel in a straight line, the battering effect is only exerted on the surface, and the back surface or areas shaded by overlapping fibers are hardly affected. No treatment effect was observed. Therefore, in order to perform low-temperature plasma treatment on the front and back sides of a fiber base fabric, it is necessary to treat the front and back sides separately, that is, the same fiber base fabric must be treated through the same process on the front and back sides. There are economic disadvantages. Another disadvantage is that it is extremely difficult to uniformly apply the sputtering effect of dissociated and ionized atoms to a large continuous area such as a fiber base fabric.

The main purpose of the present invention is to activate the surface of a synthetic resin structure to be electrolessly plated under open and mild conditions, in order to eliminate the above-mentioned drawbacks in electroless plating of synthetic resin structures. It is an object of the present invention to provide a method for forming a uniform and firmly adherent metal coating without causing a decrease in physical strength or damage to a synthetic resin structure.

Thus, according to the present invention, in the method of forming a metal film on the surface of a synthetic resin structure by electroless plating,
Prior to electroless plating, a compound containing a metal that catalyzes the decomposition of peroxide is adhered to the surface of the synthetic resin structure on which the metal film is to be formed, and then the surface of the structure is coated with an inorganic filtrate. Provided is a method for coating a surface of a synthetic resin structure with metal, which method comprises bringing the surface of a synthetic resin structure into contact with an oxide.

Synthetic resin structures to be treated by the present invention include fiber structures such as filaments, fiber yarns, cotton-like materials, tows, woven fabrics, knitted fabrics, and non-woven fabrics, as well as rod-shaped, plate-like, and This includes film forms. The material of such a structure is not particularly limited, and may be made of various synthetic resins such as polyamide, polyolefin, polyester, vinyl chloride, vinylidene chloride, polyacrylic, polycarbonate, and ABS. I can do it.

When applying electroless plating to the surface of such a synthetic resin structure (hereinafter referred to as the base material), the method of the present invention applies a decomposition reaction of harsh substances to the surface to be plated as a base prior to plating. The characteristic point is that the surface of the base material is activated by attaching a compound containing a metal that catalyzes (hereinafter referred to as a catalyst compound for convenience) and then bringing the surface of the base material into contact with an inorganic peroxide. be.

When carrying out such an activation treatment on a base material, prior to said treatment, pretreatments that are usually carried out in electroless plating of synthetic resin base materials, such as degreasing, scouring, etc., can be carried out as appropriate. For example, the base material can be degreased and refined by immersing it in an aqueous solution containing a suitable surfactant under heating.

According to the present invention, a catalyst compound is first applied to the surface of the substrate thus suitably prepared.

As the catalyst compound, one containing a metal that promotes the decomposition reaction of the inorganic peroxide, which will be described later, is used, and examples of such metals include copper, iron, nickel, aluminum, zinc, and tin. , Specific examples of compounds containing these metals include sulfates of the metals (sulfuric acid steel,
ferrous sulfate, ferric sulfate, nickel sulfate, aluminum sulfate, etc.), nitrates (copper nitrate, nickel nitrate, iron nitrate,
aluminum nitrate, etc.), chlorides (ferric chloride, copper chloride, aluminum chloride, nickel chloride, etc.).

These catalyst compounds can be attached to the surface of the substrate by immersing it in a solution containing the catalyst compound and then drying it. Generally, an aqueous solution is used as the solution, but depending on the type of the catalyst compound and/or the base material, an organic solvent solution such as alcohol or ethylene glycol or a water solution may be used.
An organic solvent mixed solution may be used, and an organic solvent having a property of swelling the synthetic resin of the base material may also be used.

The concentration of the catalyst compound in the solution is not particularly limited, but is generally conveniently within the range of 0.05 to 1 OOg/(1, preferably 0.1 to 50 g/Q).

Furthermore, if necessary, the solution may contain a cationic, nonionic, or amphoteric surfactant to improve the wettability of the substrate surface.

The temperature during treatment with the solution containing the catalytic compound is usually
Room temperature is sufficient, but in some cases the treatment may be carried out under heating up to about 100°C, and the geological time is approximately 20°C.
It can be about 180 minutes.

By removing the solvent from the base material to which the solution containing the catalyst compound has been applied by a conventional method, the catalyst compound can be deposited on the surface of the base material.

According to the present invention, the amount and/or adhesion force of the catalytic compound can be improved by subjecting the surface of the substrate to a swelling treatment, if necessary, before or at the same time as performing the above-mentioned catalytic compound adhesion treatment. can.

Such swelling treatment involves treating the surface of the base material to be plated with a liquid containing a solvent (good solvent) for the synthetic resin constituting the base material, such as dipping treatment, spraying treatment, coating treatment, etc. This can be done by Specific examples of such liquids include an aqueous solution of formic acid when the base material is a polyamide resin, a 10 to 20% aqueous solution of m-cresol or 0-cresol when the base material is a polyester resin, and vinyl chloride. or vinylidene chloride-based resin, an aqueous solution of tetrahydrofuran can be exemplified as a suitable example.

The above swelling treatment is usually suitably carried out at a temperature of room temperature to about 60°C.

The substrate, to which the catalyst compound has been deposited as described above, is then contacted with an inorganic peroxide. Examples of inorganic peroxides include hydrogen peroxide, potassium persulfate, sodium percarbonate,
Examples include ammonium persulfate, sodium perborate, and sodium percarbonate.

These are usually used in the form of an aqueous solution, but it is generally preferable to use them in combination with an acid such as sulfuric acid or an alkali such as caustic soda or caustic potash.

Although the concentration of the inorganic peroxide in the aqueous solution is not strictly limited, it can generally be in the range of 5 to 60 g/Q, preferably 10 to 50 g/Q. In addition, when sulfuric acid is used together, the concentration is usually 5 to 250 g.
/12, especially within the range of 10 to 200 g/(t), and when an alkali is used in combination, the concentration is generally 1 to 200 g/ff, preferably 5 to 150 g/ff.
/Q.

The inorganic peroxide can be brought into contact with the base material loaded with the catalyst compound, for example, by immersing the base material in an aqueous solution containing the inorganic peroxide at the above concentration. The temperature during dipping can generally be from room temperature to about 6.0 DEG C., preferably from room temperature to about 55 DEG C., and the dipping time is suitably about 20 to about 180 minutes depending on the temperature.

As a result, the catalytic compound attached to the substrate surface violently decomposes the inorganic peroxide and generates oxygen, which oxidizes and decomposes the substrate surface, forming extremely fine irregularities on the substrate surface. Chemical etching occurs and the substrate surface is activated for electroless plating. As a result, the substrate activated according to the method of the present invention has improved adsorption of chemical plating catalysts, and can form a metal coating with excellent uniformity and adhesion by electroless (chemical) plating. .

Electroless plating on the surface of the substrate activated as described above is performed by a method known per se, for example, a method described in documents such as "Surface Treatment Technology Overview" (published by Industrial Technology Service Center). I can do it. For example, electroless copper plating can be performed by using a reducing agent such as formaldehyde to deposit copper ions in a solution as metal on the surface of the plated object. The main reaction of electroless copper plating deposition is an autocatalytic reaction expressed by the following formula, when the complex of Cu''+ in the plating solution is expressed as (Cu-chelating agent).

[Cu-chelate] +2HCHO+40H-.

Cu' +2HCOO-+H! ↑+2H20+chelating agent Also, hypophosphite is the most common reducing agent for electroless nickel plating.

The basic reaction formula for electroless nickel plating is as follows (acid bath).

N i' +H*Po, -+2H'' Next, the method of the present invention will be explained in more detail with reference to Examples.

Example 1 Polyvinylidene chloride filament mesh (thread diameter 0.1
mm, 60 mesh/inch) with a nonionic surfactant (
Neugen WS-20; Dai-Kogyo Seiyaku) 5g/(2) Degreased in an aqueous solution at 40°C for 60 minutes, and washed with water after scouring.

Next, it was immersed in a 25% tetrahydrofuran aqueous solution at 25°C for 60 minutes, squeezed out, and washed with water, followed by 15 gI of ferric chloride.
It was immersed in Q aqueous solution at 25° C. for 30 minutes and dried.

Next, 80g of sulfuric acid/(2) and 15g of hydrogen peroxide (35%)
/12 mixture aqueous solution at 45° C. for 180 minutes, washed with water, dried, and then subjected to electroless copper plating under the following conditions.

A mixed solution of palladium chloride and tin chloride (
A mixed solution of Catalys t-0PC80 (Okuno Pharmaceutical) 5QmQ, 160 mff of hydrochloric acid, and 790 m12 of water was prepared.

The treated polyvinylidene chloride filament mesh was immersed in this mixed solution for 2 minutes at 25°C, then washed with water, and then immersed in a mixed solution of 50 mff of sulfuric acid and 950 wrQ of water as an activation bath for 3 minutes at 45°C to remove chloride. Palladium is fixed to the fiber.

After that, it was washed with water and placed in an electroless copper plating bath with the following composition at 28℃.
It was possible to form a uniform copper plating film by dipping for 3 minutes.

Copper plating bath composition Copper nitrate 15g/(2sodium bicarbonate 1O) Tartrate 30 Sodium hydride 207 38% formalin solution 100mff/CpH:
11.5 The copper layer formed is 25% OWf and the surface electrical resistance is 0.5
It was Ω/cm or less and was a good metal film.

Comparative Example 1 The same polyvinylidene chloride filament (thread diameter 0.1 mm, 60 mesh/inch) used in Example 1 was mixed with a nonionic surfactant (Neugen WS-20 manufactured by Kogyo Seiyaku Co., Ltd.).
Degreasing in 5g/ff aqueous solution at 40°C for 60 minutes,
After scouring, wash with water and dry.

Next, it was immersed in a 25% aqueous tetrahydrofuran solution at 25°C for 60 minutes, squeezed, washed with water, and dried.

After that, 80g/Q of sulfuric acid and 15g of hydrogen peroxide (35%)
/+2 mixture aqueous solution for 180 minutes at 45°C,
After washing with water and drying, it was immersed in an electroless plating bath at 28° C. for 3 minutes under the same conditions as in Example 1 to form a steel plating film.

The formed copper layer has a 23% OWf and a surface electrical resistance of 0.5
0/cm or less, and the metal film was good.
The adhesion strength of the metal film obtained in Example 1 was much greater than that of the metal film obtained in Comparative Example 1, as shown in Table 1 below.

Measuring method> Academic friction test: JIS L 0849 load 200g
Rub it 50 times.

Cellophane tape method: Use commercially available cellophane tape with a length of 5 to 7 cm.
Cut it and firmly press it to the test surface.

After 10 minutes, the cellophane cheap plastic Peel it off and transfer it to cellophane tape. The degree was evaluated.

Table 1 Example 2 Polyvinyl chloride filament mesh (thread diameter 0°12m
m, 50 mesh/inch) in an aqueous solution of 5 g/Q of a nonionic surfactant (Tyseri concave layer; Meisei Chemical Co., Ltd.).
After degreasing and scouring at ℃ for 60 minutes, it was washed with water and dried.

Next, it was immersed in a 20% acetone aqueous solution at 25°C for 180 minutes, squeezed and washed with water, then immersed in an aqueous solution of 20g/Q nitric acid steel at 30°C for 120 minutes, dried, and then mixed with sulfuric acid 100g/I2 and sodium perborate. 1 at 25°C to a 20g/Q mixture aqueous solution.
After being immersed for 80 minutes, washed with water, and dried, electroless copper plating was performed.

The electroless plating conditions were the same as in Example 1, and as a result,
A uniform plating film was obtained.

The amount of plated copper film is 30% OWf, and the surface electrical resistance is 0.
3Ω/cm, indicating a good electrically conductive metallized fiber.

Comparative Example 2 In the same manner as in Example 2, a polyvinyl chloride filament mesh (thread diameter 0.12 mm, 150 meshes/inch) that had been scoured and degreased was immersed in a 20% acetone aqueous solution at 25°C for 3 hours, squeezed, and washed with water. .

Next, it was immersed in a mixed aqueous solution of 100 g/<2 sulfuric acid and 20 g/a of sodium perphosphate at 25° C. for 180 minutes, washed with water, dried, and electroless copper plating was performed.

The electroless copper plating conditions were the same as in Example 1, and as a result, a uniform plating film was obtained.

The amount of plated copper film is 28% OWf, and the surface electrical resistance is 0.
3 Ω/cm, indicating that the metalized fibers had good conductivity. However, the results of comparing the adhesion strength of the metal coatings of Example 2 and Comparative Example 2 using the academic friction test and the cellophane tape method were as follows. , as shown in Table 2 below, and the adhesive strength of Example 2 was greater.

Table 2 Example 3 Polyester filament mesh (thread diameter 00045 m
m, 135 mesh/inch) with a nonionic surfactant (
5 in an aqueous solution of 3g/Q
After degreasing and scouring at 0°C for 60 minutes, it was washed with water and dried. Next, it was immersed in a 25 g/Q aqueous solution of nickel nitrate at 30° C. for 180 minutes and dried.

Next, it was immersed in a mixed aqueous solution of caustic soda loOg/(1 and ammonium persulfate 50 g/Q) at 40° C. for 120 minutes, washed with water, dried, and electroless steel nickel plated.

The electroless nickel plating conditions are as follows.

Nickel plating bath composition Nickel hypophosphite 28 g/Q boric acid
12/l ammonium sulfate
3 Sodium acetate 5
//pH: 6.0 As a result of immersion in a nickel plating bath at 33° C. for 6 minutes, a uniform nickel film was formed. The amount of nickel plating deposited was 28% OWf, the surface electrical resistance was 1.50/cm, and the metallized fiber had good conductivity.

Comparative Example 3 A polyester filament mesh similar to Example 3 (
After scouring 5135 meshes/inch with a thread diameter of 0.045 mm, it was squeezed, washed with water, and dried. Then, 10 ml of caustic soda
After soaking in a mixed aqueous solution of 0 g/Q and ammonium persulfate 50 g/(! at 40°C for 120 minutes, washing with water, and drying,
Electroless nickel plating was performed under the same conditions as in Example 3.

As a result, a uniform nickel plating film was formed, and the nickel plating film had a 25% OWf and an electrical resistance of 2.2Ω.
/ cm, and it was a good conductive mesh, but
Comparing the adhesion strength of nickel plating films, Table 3 below shows
As shown in Figure 3, Example 3 was superior to Comparative Example 3.

Table 3 Example 4 Polyamide magic fastener A side and B side (Yoshida Kogyo) were treated with nonionic surfactant (WS-20i Dai-Kogyo Seiyaku)
After degreasing and scouring in a 3 g/Q aqueous solution at 50°C for 6 minutes, it was washed with water and dried. Then, 25° in 50% formic acid aqueous solution.
After washing with water, it was immersed in a 20 g/Q aqueous solution of tin sulfate at 25°0 for 120 minutes and dried.

Next, it was immersed in a mixed aqueous solution of 50 g/Q of sulfuric acid and 20 g/Q of sodium percarbonate at 45°C for 180 minutes, washed with water, and dried.
Electroless copper plating was performed under the same conditions as in Example 1. As a result, a uniform plating film was obtained. The amount of plated copper film is 2
At 5% OWf, the surface electrical resistance was 0.50/cm, indicating good conductivity.

Comparative Example 4 The same polyamide Magic 7 Asner (manufactured by Shoide Kogyo) as in Example 4 was degreased in an aqueous solution of 3 g/I2 of a nonionic surfactant (WS-20: Daiichi Kogyo Seiyaku) at 50°C for 60 minutes. After scouring, it was washed with water and dried.

Next, it was immersed in a 50% formic acid aqueous solution at 25°C for 30 minutes, and after washing with water, 50 g/Q of sulfuric acid and 20 g/Q of sodium percarbonate were added.
The sample was immersed in a mixed aqueous solution of 1.1 at 45° C. for 180 minutes, washed with water, and dried, followed by copper plating under the same conditions as in Example 1. As a result, a uniform plating film was obtained, and the amount of the plating film was 2
At 8% OWf, the surface electrical resistance was 0.5 Ω/cm and the conductivity was good. However, after repeatedly removing the plated A side and B side 50 times, the results were as follows: 4
As shown in Figure 4, the product of Example 4 is far superior.

Table-4

Claims (1)

[Claims] 1. In a method for forming a metal coating on the surface of a synthetic resin structure by electroless plating, prior to electroless plating,
A compound containing a metal that catalyzes the decomposition of peroxide is attached to the surface of the synthetic resin structure on which the metal coating is to be formed, and then the surface of the structure is brought into contact with an inorganic peroxide. A method for metal coating the surface of a synthetic resin structure, characterized by: 2. The surface of the synthetic resin structure on which the metal coating is to be formed,
2. The method according to claim 1, wherein the synthetic resin is treated with a liquid containing a solvent before or at the same time as the adhesion treatment.