JP2023060704A - Electroless plating method - Google Patents

Abstract

To provide an electroless plating method capable of showing a high plating precipitation property and forming a coating film having a high adhesion to a resin material.SOLUTION: An electroless plating method for a resin material includes: (1) a step 1 where a surface to be treated of a resin material is brought into contact with a composition for pretreatment; (2) a step 2 where the surface to be treated of the resin material is brought into contact with an activation treatment liquid; and (3) a step 3 where the surface to be treated of the resin material is contacted to an electroless plating liquid. The composition for pretreatment contains manganese ions of 10 mg/L or more and monovalent silver ions of 10 mg/L or more and has a pH of 2 or less.SELECTED DRAWING: None

Description

The present invention relates to an electroless plating method.

BACKGROUND ART In recent years, resin materials (resin moldings) have been used as automotive parts for the purpose of reducing the weight of automobiles. For such purposes, ABS resin, PC/ABS resin, PPE resin, polyamide resin, etc., are used as resin materials, and are plated with copper, nickel, or the like in order to impart a sense of luxury and beauty. ing. Furthermore, as a method of imparting electrical conductivity to a resin substrate to form a conductive circuit, a method of forming a plating film of copper or the like on a resin substrate has been used.

As a general method for forming a plating film on a resin material such as a resin substrate or a resin material, after roughening the surface of the resin material by etching treatment with chromic acid, neutralization and pre-dipping are performed as necessary, Next, an electroless plating catalyst is applied using a colloidal solution containing a tin compound and a palladium compound, followed by activation treatment (accelerator treatment) for removing tin, followed by electroless plating and electroplating in sequence. How to do is done.

However, the above method has the problem that it is harmful to the environment and the human body because it uses chromic acid. In addition, since expensive palladium is used to provide the catalyst, there is a problem of high costs.

As a method for forming a plating film on a resin material, an aqueous solution containing a metal activator molecular species is brought into contact with a part to be plated to etch it, and the metal activator molecular species is brought into contact with a reducing agent solution capable of reducing the metal activator molecular species. , a method of metal plating by contacting the parts with an electroless plating solution has been proposed (see Patent Document 1).

However, in the method described in Patent Document 1, there is room for examination of the component of the activator molecular species, and there is a problem that the plating film is not sufficiently formed. It is difficult to form a plating film on resin materials such as the ABS resin described above, and in particular, it is difficult to form a plating film on PC/ABS resin. is not sufficient.

Therefore, there is a demand for the development of an electroless plating method capable of exhibiting high deposition properties of plating and forming a plating film having high adhesion to a resin material.

Japanese Patent No. 4198799

The present invention has been made in view of the above problems, and provides an electroless plating method capable of exhibiting high plating deposition properties and forming a plating film having high adhesion to a resin material. With the goal.

As a result of intensive research to achieve the above object, the present inventors have found that, in a method for electroless plating of a resin material, (1) a pretreatment composition having a specific composition and pH is added to the surface to be treated of the resin material; (2) contacting the surface to be treated of the resin material with an activation treatment solution (2); and (3) contacting the surface to be treated of the resin material with an electroless plating solution (3). The inventors have found that the above object can be achieved by the electroless plating method for a resin material having the configuration, and have completed the present invention.

That is, the present invention relates to the following electroless plating method.
1. An electroless plating method for a resin material,
(1) Step 1 of contacting the surface of the resin material to be treated with the pretreatment composition;
(2) step 2 of bringing the treated surface of the resin material into contact with an activation treatment liquid; and (3) step 3 of bringing the treated surface of the resin material into contact with an electroless plating solution,
The pretreatment composition contains 10 mg/L or more of manganese ions and 10 mg/L or more of monovalent silver ions, and the pH of the pretreatment composition is 2 or less. Electroplating method.
2. Item 2. The electroless plating method according to item 1, wherein the activation treatment liquid is an aqueous solution containing at least one compound selected from the group consisting of alkaline compounds and inorganic acids.
3. Item 3. The electroless plating method according to item 2, wherein the alkali compound is at least one selected from the group consisting of alkali metal hydroxides, alkaline earth metal hydroxides, and alkali metal carbonates.
4. Item 4. The electroless plating method according to Item 2 or 3, wherein the inorganic acid is a boron-containing compound.
5. Item 5. The electroless plating method according to any one of items 1 to 4, wherein the activation treatment liquid has a pH of 8 to 13.
6. Item 6. The electroless plating method according to any one of Items 1 to 5, wherein the electroless plating solution contains a reducing agent exhibiting catalytic activity for silver.
7. Item 7. The electroless plating method according to any one of Items 1 to 6, wherein the manganese ions have a valence of 3 or more.

According to the electroless plating method of the present invention, it is possible to exhibit a high deposition property of plating and form a plating film having high adhesion to a resin material.

The present invention will be described in detail below.

1. Method for Electroless Plating of Resin Material The method for electroless plating of a resin material of the present invention comprises (1) a step 1 of contacting the surface of the resin material to be treated with a pretreatment composition; and (3) step 3 of contacting the treated surface of the resin material with an electroless plating solution. L or more of manganese ions and 10 mg/L or more of monovalent silver ions are contained, and the pretreatment composition has a pH of 2 or less.

In the electroless plating method of the present invention, in step 1, the surface to be treated of the resin material is brought into contact with a pretreatment composition having a specific composition and pH, and in step 2, after going through step 1, to be treated. Since the surface is brought into contact with the activation treatment liquid, it is possible to sufficiently form a plating film even with a resin material such as ABS resin, particularly a resin material such as PC/ABS resin, which is difficult to form a plating film.

According to the electroless plating method of the present invention, in step 1, the surface to be treated of the resin material is brought into contact with the pretreatment composition, thereby etching the surface to be treated and adding silver to the surface to be treated. Since a catalyst can be applied and a catalyst application step and an accelerator treatment step are not required, the treated surface of the resin material can be easily treated, and the number of steps during electroless plating can be reduced. be able to.

For example, in a pretreatment composition containing manganese ions and palladium ions, the inclusion of palladium ions reduces the etching power of manganese ions. In addition, in the pretreatment composition containing chromic acid and silver ions, silver chromate (Ag ₂ CrO ₄ ) precipitates, which are insoluble precipitates in the composition, and silver ions are discharged out of the system. Catalyst is not applied sufficiently.

On the other hand, the pretreatment composition used in step 1 of the electroless plating method of the present invention contains manganese ions and monovalent silver ions, so that after bringing the surface to be treated of the resin material into contact, By bringing the surface to be treated into contact with the electroless plating solution, a plating film with good adhesion can be formed on the surface to be treated.

In addition, since the pretreatment composition used in step 1 of the present invention contains manganese ions and monovalent silver ions, the surface to be treated of the resin substrate is brought into contact with the composition to etch the surface to be treated and provide a catalyst. can be performed at the same time, the catalyst application step can be omitted.

Furthermore, the pretreatment composition used in step 1 of the present invention does not require the use of a palladium-tin colloidal solution as in the conventional catalyst application step, and an activation treatment (accelerator treatment) for removing tin. ) process can also be omitted.

That is, according to the pretreatment composition used in step 1 of the electroless plating method of the present invention, high plating deposition can be obtained in electroless plating in the subsequent step without using harmful chromic acid and expensive palladium. You can show your sexuality. Further, according to the pretreatment composition used in step 1 of the electroless plating method of the present invention, the etching step and the catalyst application step do not need to be performed separately, and the accelerator treatment step does not need to be performed. The process for electroless plating is greatly shortened.

In addition, the electroless plating method of the present invention includes step 2 in which the surface to be treated of the resin material that has undergone step 1 is brought into contact with the activation treatment liquid, so that step 1 and step 2 are included. , the treated surface of the resin material can be further activated, and in the subsequent step 3, by bringing the treated surface of the resin material into contact with the electroless plating solution, high plating deposition properties can be exhibited. It is possible to form a plating film having high adhesion to the resin material.

(resin material)
In the electroless plating method of the present invention, the resin forming the resin material to be processed is not particularly limited, and various resin materials conventionally subjected to etching treatment with a mixed acid of chromic acid and sulfuric acid can be used. can be formed, and a good electroless plating film can be formed on the resin material. Examples of the resin forming the resin material include acrylonitrile-butadiene-styrene copolymer resin (ABS resin), resin in which the butadiene rubber component of ABS resin is replaced with acrylic rubber component (AAS resin), and butadiene rubber component of ABS resin. is replaced with an ethylene-propylene rubber component (AES resin) and other styrene resins. Also, an alloyed resin of the above styrene resin and polycarbonate (PC) resin (PC/ABS resin: for example, an alloyed resin having a PC resin mixing ratio of about 30 to 70% by mass) can be suitably used. Furthermore, polyphenylene ether resins, polyphenylene oxide resins, polybutylene terephthalate (PBT) resins, polyphenylene sulfide (PPS) resins, polyamide resins, etc., which are excellent in heat resistance and physical properties, can also be used. According to the electroless plating method of the present invention, even with a resin material such as PC/ABS resin, which is particularly difficult to form a plating film, high plating deposition properties can be exhibited, and plating with high adhesion to the resin material can be obtained. A film can be formed.

The shape, size, etc. of the resin material are not particularly limited, and according to the electroless plating method of the present invention, high plating deposition properties and adhesion to the resin material are exhibited even for large resin materials having a large surface area. It is possible to form a good plating film excellent in decorativeness, physical properties, and the like. Such large resin materials include automotive parts such as radiator grills, wheel caps, medium- and small-sized emblems, and door handles; exterior parts in the electric and electronic fields; ; gaming machine-related goods such as pachinko parts;

(Step 1)
Step 1 is a step of bringing the treated surface of the resin material into contact with the pretreatment composition. The pretreatment composition used in step 1 contains 10 mg/L or more of manganese ions and 10 mg/L or more of monovalent silver ions, and has a pH of 2 or less.

(manganese ion)
Manganese ions contained in the pretreatment composition are not particularly limited as long as they have oxidizing power. The manganese valence of the manganese ion is preferably 3 or more, more preferably 4 or more, and still more preferably 7. For example, the manganese ions contained in the pretreatment composition may be in the form of manganese ions of simple metal ions such as trivalent manganese ions and tetravalent manganese ions, and manganese ions of heptavalent manganese. It may be in the form of manganese ions such as permanganate ions. Among these, tetravalent manganese ions and permanganate ions are preferred, and permanganate ions are more preferred, in terms of more excellent etching power. In addition, manganese ions of divalent manganese do not have oxidizing power, and etching of the surface of the resin material does not proceed even when used alone, but they are used in combination with manganese ions of manganese with a valence of 3 or more. You may

A manganese ion may be used individually by 1 type, and may use 2 or more types together.

The manganese salt for imparting manganese ions to the pretreatment composition is not particularly limited, and manganese (II) sulfate, manganese (III) phosphate, manganese (IV) oxide, sodium permanganate (VII), permanganate (VII), Potassium manganate (VII) and the like can be mentioned. Among these, manganese phosphate (III), manganese oxide (IV), sodium permanganate (VII), and potassium permanganate (VII) are used in that they can impart manganese ions with superior etching power. Preferred are sodium permanganate (VII) and potassium permanganate (VII).

A manganese salt may be used individually by 1 type, and may use 2 or more types together.

The content of manganese ions in the pretreatment composition is 10 mg/L or more. If the content of manganese ions is less than 10 mg/L, the resin material cannot be sufficiently etched, and the adhesion of the film formed by electroless plating decreases. The manganese ion content is preferably 10 mg/L to 100 g/L, more preferably 100 mg/L to 50 g/L, still more preferably 0.2 g/L to 30 g/L, and 0.5 g/L to 15 g/L. is particularly preferred, and 0.5 g/L to 10 g/L is most preferred. By setting the lower limit of the manganese ion content within the above range, the etching power of the pretreatment composition is further improved. Further, by setting the upper limit of the manganese ion content within the above range, the formation of precipitates of manganese dioxide in the pretreatment composition is further suppressed, and the bath stability is further improved.

(silver ion)
The silver ions contained in the pretreatment composition are monovalent silver ions. As the silver salt for imparting monovalent silver ions, a counter ion capable of imparting stable monovalent silver ions in the bath when dissolved in the pretreatment composition and forming a silver salt is used. is not particularly limited as long as it does not adversely affect manganese ions. Specific examples include silver (I) sulfate, silver (I) nitrate, and silver (I) oxide. Among these, silver nitrate (I) is preferred because of its high solubility and ease of industrial use. In addition, it is even more suitable for resin materials formed from resins that are difficult to deposit plating, such as acrylonitrile-butadiene-styrene copolymer resin (ABS resin), alloyed resin of styrene resin and polycarbonate (PC) resin, etc. Silver (I) sulfate is preferable in that the deposition property of the plating is good and the adhesion of the plating film is less likely to decrease.

A silver salt may be used individually by 1 type, and may use 2 or more types together.

The content of monovalent silver ions in the pretreatment composition is 10 mg/L or more. If the content of monovalent silver ions is less than 10 mg/L, electroless plating cannot be sufficiently deposited. The content of monovalent silver ions is preferably 10 mg/L to 20 g/L, more preferably 50 mg/L to 15 g/L, even more preferably 100 mg/L to 10 g/L. By setting the lower limit of the content of monovalent silver ions within the above range, a sufficient amount of the silver catalyst is adsorbed on the surface of the resin material, and the electroless plated film is more sufficiently deposited. In addition, even if the upper limit of the content of monovalent silver ions is equal to or higher than the above upper limit, there is no adverse effect. be able to.

As silver ions, monovalent silver obtained by adding metallic silver to an acidic manganese bath and dissolving it may also be used. The acid for forming the acidic manganese bath is not particularly limited, and inorganic acids and organic sulfonic acids can be used.

Inorganic acids include sulfuric acid, phosphoric acid, nitric acid, hydrochloric acid, hydrofluoric acid, boric acid and the like. Among these, sulfuric acid is preferable because it is more excellent in wastewater treatment properties.

Examples of organic sulfonic acids include aliphatic sulfonic acids having 1 to 5 carbon atoms such as methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid and pentanesulfonic acid; aromatic sulfonic acids such as toluenesulfonic acid, pyridinesulfonic acid and phenolsulfonic acid. etc. Among these, aliphatic sulfonic acids having 1 to 5 carbon atoms are preferable in terms of good bath stability of the pretreatment composition.

The acid may be used singly or in combination of two or more.

The acid concentration in the pretreatment composition of the present invention is not particularly limited. For example, the total acid concentration is preferably 100 to 1800 g/L, more preferably 800 to 1700 g/L.

(other ingredients)
The pretreatment composition may contain a polymer compound in addition to the manganese ions and the silver ions. The type of polymer compound is not particularly limited, and a cationic polymer can be preferably used in that it can promote plating deposition. The content of the polymer compound is preferably 0.01 to 100 g/L, more preferably 0.1 to 10 g/L.

(solvent)
The pretreatment composition preferably contains the manganese ions, the silver ions, and optionally other components in a solvent. The solvent is not particularly limited, and includes water, alcohol, mixed solvent of water and alcohol, and the like.

The solvent is preferably water from the viewpoint of excellent safety, that is, the pretreatment composition is preferably an aqueous solution.

The alcohol is not particularly limited, and conventionally known alcohols such as ethanol can be used.

When a mixed solvent of water and alcohol is used, the alcohol concentration is preferably low, and specifically, the alcohol concentration is preferably about 1 to 30% by mass.

In step 1, the pH of the pretreatment composition is 2 or less. If the pH of the pretreatment composition exceeds 2, the etching treatment of the resin material is not sufficient. The pH of the pretreatment composition is preferably 1 or less.

The method for contacting the surface of the resin material to be treated with the pretreatment composition is not particularly limited, and a conventionally known method may be used. Examples of the method include a method of immersing the resin material in the pretreatment composition, a method of spraying the pretreatment composition onto the surface of the resin material to be treated, and the like. Among these methods, the method of immersing the resin material in the pretreatment composition is preferable because it is more excellent in contact efficiency.

The temperature of the pretreatment composition in step 1 is not particularly limited, and is preferably 30 to 100°C, more preferably 40 to 90°C, even more preferably 50 to 80°C. By setting the lower limit of the temperature of the pretreatment composition within the above range, etching of the surface of the resin material and application of the catalyst become more sufficient. Further, by setting the upper limit of the temperature of the pretreatment composition within the above range, it is possible to obtain a film appearance that is even more excellent in decorativeness.

In step 1, the contact time between the pretreatment composition and the surface of the resin material to be treated is preferably 3 to 60 minutes, more preferably 5 to 50 minutes, and even more preferably 10 to 40 minutes. By setting the lower limit of the contact time within the above range, etching of the surface of the resin material and application of the catalyst become more sufficient. Further, by setting the upper limit of the contact time within the above range, it is possible to obtain a film appearance that is even more excellent in decorativeness.

When the conventional chromic acid-sulfuric acid mixed solution is used, silver chromate (Ag ₂ CrO ₄ ) precipitates immediately after the addition of monovalent silver ions to the bath. It cannot exist stably as ions in matter. Therefore, when the conventional chromic acid-sulfuric acid mixed solution is used, it is difficult to use a pretreatment composition containing silver ions as in the present invention.

Through step 1 described above, the surface to be treated of the resin material is brought into contact with the pretreatment composition, and the surface to be treated is treated.

(Degreasing process)
The electroless plating method of the present invention may have a degreasing treatment step for degreasing before step 1 in order to remove stains on the treated surface of the resin material. The degreasing treatment is not particularly limited, and the degreasing treatment may be performed by a conventionally known method.

(Post-treatment process)
In the electroless plating method of the present invention, between step 1 and step 2 described later, a post-treatment liquid containing an inorganic acid is used to remove manganese adhering to the surface of the resin material. It may have a post-processing step for processing.

The inorganic acid is not particularly limited, and examples thereof include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, hydrofluoric acid, boric acid and the like. Among these, hydrochloric acid is preferable because it is excellent in removing manganese.

The above inorganic acids may be used singly or in combination of two or more.

The content of the inorganic acid in the post-treatment liquid is not particularly limited, and may be about 1 to 1000 g/L.

The post-treatment method is not particularly limited, and for example, the resin material pretreated in step 1 may be immersed in a post-treatment liquid having a liquid temperature of about 15 to 70° C. for about 1 to 10 minutes. The post-treatment can further improve the depositability, adhesion and appearance of the formed plating film.

(Step 2)
Step 2 is a step of bringing the treated surface of the resin material into contact with the activation treatment liquid.

The activation treatment liquid used in step 2 is not particularly limited as long as it can activate the treated surface of the resin material that has undergone step 1, but the activation treatment liquid is selected from the group consisting of alkaline compounds and inorganic acids. An aqueous solution containing at least one selected compound is preferred.

(alkali compound)
The alkali compound contained in the activation treatment liquid is not particularly limited as long as it can activate the treated surface of the resin material that has undergone step 1 above. Examples of such alkali compounds include alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal carbonates, and the like. Among these, alkali metal hydroxides and alkali metal carbonates are preferred from the viewpoint of further improving the depositability of plating and adhesion to resin materials.

Alkali metal hydroxides include sodium hydroxide, potassium hydroxide, lithium hydroxide and the like. Among these, sodium hydroxide and potassium hydroxide are preferable from the viewpoint of further improving the depositability of the plating and the adhesion to the resin material.

Alkaline earth metal hydroxides include calcium hydroxide, strontium hydroxide, barium hydroxide and the like. Among these, strontium hydroxide and barium hydroxide are preferable from the viewpoint of further improving the depositability of the plating and the adhesion to the resin material.

Alkali metal carbonates include sodium carbonate, potassium carbonate, lithium carbonate and the like. Among these, sodium carbonate and potassium carbonate are preferable from the viewpoint of further improving the depositability of the plating and the adhesion to the resin material.

(inorganic acid)
The inorganic acid contained in the activation treatment liquid is not particularly limited as long as it can activate the treated surface of the resin material that has undergone step 1 above. Examples of such inorganic acids include boron-containing compounds. By using a boron-containing compound or the like as the inorganic acid, the depositability of the plating and the adhesion to the resin material are further improved. Further, a boron-containing compound that does not exhibit reducing properties is more preferable in that it does not affect electroless plating in step 3 described later.

Boric acid and its salts can be used as the boron-containing compound. Specific examples of borates include sodium tetraborate, potassium tetraborate, and lithium tetraborate. Among these, boric acid and sodium tetraborate are preferable from the viewpoint of further improving the depositability of the plating and the adhesion to the resin material. In addition, boric acid, sodium tetraborate, potassium tetraborate, and lithium tetraborate can be used as the boron-containing compound that does not exhibit the reducing property.

The compounds contained in the activation treatment liquid may be used singly or in combination of two or more.

In the activation treatment liquid, the content of the above compound is preferably 0.5 g/L or more, more preferably 1 g/L or more, still more preferably 2 g/L or more, and particularly preferably 5 g/L or more. The content of the above compound is preferably 200 g/L or less, more preferably 100 g/L or less, still more preferably 50 g/L or less, and particularly preferably 20 g/L or less. By setting the upper limit and the lower limit of the content of the compound in the above range, the depositability of the plating and the adhesion to the resin material are further improved.

(other ingredients)
The activation treatment liquid may contain other components in addition to the above alkaline compound and inorganic acid. Other components include pH adjusters, surfactants, and the like.

Hydrochloric acid, sulfuric acid, etc. are mentioned as a pH adjuster at the time of adjusting pH low. Examples of the pH adjusting agent for adjusting the pH to a high level include aqueous sodium hydroxide solution and aqueous ammonia solution.

(solvent)
The activation treatment liquid preferably contains the above-mentioned compound and other components added as necessary in a solvent. The solvent is not particularly limited, and includes water, alcohol, mixed solvent of water and alcohol, and the like.

The solvent is preferably water from the viewpoint of excellent safety, that is, the activation treatment liquid is preferably an aqueous solution.

The alcohol is not particularly limited, and conventionally known alcohols such as ethanol can be used.

When a mixed solvent of water and alcohol is used, the alcohol concentration is preferably low, and specifically, the alcohol concentration is preferably about 1 to 30% by mass.

In step 2, the pH of the activation treatment solution is preferably 7-13, more preferably 8-13, even more preferably 9-12. When the pH of the activation treatment liquid is within the above range, the depositability of the plating and the adhesion to the resin material are further improved.

The method of bringing the treated surface of the resin material into contact with the activation treatment liquid is not particularly limited, and a conventionally known method may be used. Examples of the method include a method of immersing the resin material in the activation treatment liquid, a method of spraying the activation treatment liquid onto the treated surface of the resin material, and the like. Among these methods, the method of immersing the resin material in the activation treatment liquid is preferable because it is more excellent in contact efficiency.

The temperature of the activation treatment liquid in step 2 is not particularly limited, and is preferably 5 to 60°C, more preferably 15 to 50°C, and even more preferably 25 to 40°C. By setting the lower limit of the temperature of the activation treatment liquid within the above range, the surface of the resin material can be more sufficiently activated. Further, by setting the upper limit of the temperature of the activation treatment liquid within the above range, it is possible to obtain a film appearance that is even more excellent in decorativeness.

In step 2, the contact time between the activation treatment liquid and the treated surface of the resin material is preferably 1 second to 10 minutes, more preferably 10 seconds to 5 minutes, and even more preferably 30 seconds to 3 minutes. By setting the lower limit of the contact time within the above range, the activation of the surface of the resin material becomes more sufficient. Further, by setting the upper limit of the contact time within the above range, it is possible to obtain a film appearance that is even more excellent in decorativeness.

Through step 2 described above, the surface to be treated of the resin material is brought into contact with the activation treatment liquid, and the surface to be treated is activated.

(Step 3)
Step 3 is a step of bringing the treated surface of the resin material into contact with an electroless plating solution.

The method of bringing the treated surface of the resin material into contact with the electroless plating solution is not particularly limited, and a conventionally known method may be used. As the method, a method of immersing the surface of the resin material to be treated in the electroless plating solution is preferable in that the contact efficiency is further excellent.

The electroless plating solution is not particularly limited, and conventionally known autocatalytic electroless plating solutions can be used. Examples of the electroless plating solution include electroless nickel plating solution, electroless copper plating solution, electroless cobalt plating solution, electroless nickel-cobalt alloy plating solution, electroless gold plating solution, electroless silver plating solution, and the like. .

The electroless plating solution preferably contains, as a reducing agent, a reducing agent that exhibits catalytic activity with respect to silver. Examples of the reducing agent include dimethylamine borane, formalin, glyoxylic acid, tetrahydroboric acid, hydrazine and the like.

The conditions for contacting the surface of the resin material to be treated with the electroless plating solution are not particularly limited. and the immersion time is about 3 to 30 minutes.

The content of the reducing agent in the electroless plating solution is not particularly limited, and is preferably about 0.01 to 100 g/L, more preferably about 0.1 to 10 g/L. By setting the lower limit of the content of the reducing agent in the above range, the deposition property of the plating is further improved, and by setting the upper limit of the content of the reducing agent in the above range, the stability of the electroless plating bath is further improved. improves.

In the electroless plating method of the present invention, step 3 may be repeated two or more times, if necessary. By repeating step 3 two or more times, two or more layers of electroless plating films are formed.

Through step 3 described above, the surface of the resin material to be treated is brought into contact with the electroless plating solution to form an electroless plating film.

(Reduction treatment step)
In the electroless plating method of the present invention, in order to improve the depositability of electroless plating, a reduction treatment is performed with a reducing treatment liquid containing a reducing agent and/or an organic acid between steps 2 and 3. good too.

The reducing agent used in the reduction treatment is not particularly limited, and includes dimethylamine borane, formalin, glyoxylic acid, hydrazine, hypophosphite, erythorbic acid, ascorbic acid, hydroxylamine sulfate, hydrogen peroxide, glucose and the like. Among these, dimethylamine borane, formalin, glyoxylic acid, and hydrazine are preferable in terms of better plating deposition properties.

The above reducing agents may be used singly or in combination of two or more.

The concentration of the reducing agent in the reducing treatment liquid is not particularly limited, and is preferably 0.1 to 500 g/L, more preferably about 1 to 50 g/L, and even more preferably 2 to 25 g/L.

The organic acid used for the reduction treatment is not particularly limited, and formic acid, oxalic acid, glycolic acid, tartaric acid, citric acid, maleic acid, acetic acid, propionic acid, malonic acid, succinic acid, lactic acid, malic acid, gluconic acid, glycine, Alanine, aspartic acid, glutamic acid, iminodiacetic acid, nitrilotriacetic acid, fumaric acid and the like. Among these, formic acid, oxalic acid, glycolic acid, tartaric acid, citric acid, and maleic acid are preferable in terms of better plating deposition properties.

The above organic acids may be used singly or in combination of two or more.

The concentration of the organic acid in the reduction treatment liquid is not particularly limited, and is preferably 0.1 to 500 g/L, more preferably about 1 to 50 g/L, and even more preferably 2 to 25 g/L.

The method of reduction treatment is not particularly limited, and for example, the resin material activated in step 2 may be immersed in a reduction treatment liquid having a liquid temperature of about 15 to 50° C. for about several seconds to 10 minutes.

(Electroplating process)
The electroless plating method for the resin material of the present invention may further include an electroplating step after step 3.

In the electroplating step, after step 3 above, if necessary, the substrate may be treated with an aqueous solution of an acid, an alkali, or the like, immersed in an electroplating solution, and electroplated.

The electroplating solution is not particularly limited, and may be appropriately selected from conventionally known electroplating solutions according to the purpose.

The electroplating method is not particularly limited. It may be immersed for several seconds to 10 minutes under conditions of about ² .

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples. However, the present invention is not limited to the examples.

(Preparation of electroless plating film)
As a resin material to be plated, a flat plate (10 cm × 5 cm × 0.3 cm, surface area: about 1 dm ² ) of ABS resin (manufactured by Techno UMG Co., Ltd., trade name: ABS3001M) and PC/ABS resin (Techno UMG ( Co., Ltd.
A flat plate (trade name: TC25M) (10 cm x 5 cm x 0.3 cm, surface area of about 1 dm ² ) was prepared, and an electroless plating film was formed by the following method.

First, the resin material was immersed at 40° C. for 5 minutes in an alkaline degreasing solution (manufactured by Okuno Chemical Industry Co., Ltd., A-SCREEN A-220 bath) and washed with water.

Then, according to the formulations shown in Table 1, the pretreatment composition, the activation treatment solution, and the electroless plating solution used in each example and comparative example were prepared. These liquids were prepared by adding additives according to the formulations shown in Table 1 to water as a solvent and stirring the mixture. The activation treatment liquid used in Example 6 was prepared by adding only a pH adjuster to water as a solvent to adjust the pH.

Using each solution prepared as described above, the test pieces were sequentially subjected to steps 1 to 3 under the following conditions to form an electroless plated film. In Comparative Example 1, Step 2 was not performed.

(Step 1)
Immersion in pretreatment composition: immersion temperature 68°C, immersion time 10 minutes

(Step 2)
Immersion in activation treatment liquid: immersion temperature 35° C., immersion time 2 minutes In step 2, the pH of the activation treatment liquid was adjusted using the following pH adjuster.
・10g/L _NaOH aqueous solution ・10g/L _H2SO4 aqueous solution

(Step 3)
Immersion in electroless plating solution: immersion temperature 40°C, immersion time 10 minutes

Using the resin materials of Examples and Comparative Examples to which the electroless plating solution was applied by the above method, the coverage and adhesion of the plated films formed were evaluated by the following methods.

(1) Coverage ratio The ratio of the area of the surface of the resin material on which the electroless plated film was formed was evaluated as the coverage ratio. The coverage rate was 100% when the entire surface of the resin material was covered.

(2) Peel strength measurement The resin material on which the electroless plating film is formed is immersed in a copper sulfate plating bath, and electroplating is performed for 120 minutes at a current density of 3 A/dm ² and a temperature of 25°C to remove the copper plating film. formed and samples were made. The samples were dried at 80° C. for 120 minutes and allowed to reach room temperature. Next, a 10 mm wide cut was made in the plating film, and a tensile tester (manufactured by Shimadzu Corporation, Autograph AGS-J) was used.
1 kN), the plating film was pulled in the direction perpendicular to the surface of the resin material, and the peel strength was measured.

Table 1 shows the results.

From the results in Table 1, it is clear that the pretreatment composition has steps 1 to 3, contains 10 mg/L or more of manganese ions and 10 mg/L or more of monovalent silver ions, and has a pretreatment composition. pH is 2
It was found that the plating films formed in Examples 1 to 6 below had a high coating ratio and excellent adhesion.

In addition, the plating film formed by immersing in the electroless plating solution after being immersed in the pretreatment composition and the activation treatment solution of Examples 1 to 6 had a coverage of the resin material formed by the ABS resin. is 100%, the coverage of the resin material formed by PC/ABS is 100% or 50%, and the immersion time in the pretreatment composition is 10 minutes. It was found that there is no need to increase the coverage by adding a catalyst in a separate catalyst application step in order to indicate the coverage.

In Comparative Example 1, in which the step 2 of contacting the surface of the resin material to be treated with the activation treatment liquid was not performed, when the step 1 was performed under the severe condition of immersing the surface of the resin material in the pretreatment composition for 10 minutes, It was found that the coverage of the plating film was low and the adhesion was also low.

Comparative Example 2 using a pretreatment composition containing no manganese ions, and Comparative Example 3 using a pretreatment composition having a manganese ion concentration of less than 10 mg / L, the plating film coverage is low, It was found that the adhesiveness was also low.

Furthermore, in Comparative Examples 4 and 5 using the pretreatment composition having a monovalent silver ion concentration of less than 10 mg/L, it was found that the coating rate of the plating film was low and the adhesion was also low.

Claims (7)

An electroless plating method for a resin material,
(1) Step 1 of contacting the surface of the resin material to be treated with the pretreatment composition;
(2) step 2 of bringing the treated surface of the resin material into contact with an activation treatment liquid; and (3) step 3 of bringing the treated surface of the resin material into contact with an electroless plating solution,
The pretreatment composition contains 10 mg/L or more of manganese ions and 10 mg/L or more of monovalent silver ions, and the pH of the pretreatment composition is 2 or less. Electroplating method. 2. The electroless plating method according to claim 1, wherein said activation treatment liquid is an aqueous solution containing at least one compound selected from the group consisting of alkaline compounds and inorganic acids. 3. The electroless plating method according to claim 2, wherein said alkali compound is at least one selected from the group consisting of alkali metal hydroxides, alkaline earth metal hydroxides and alkali metal carbonates. 4. The electroless plating method according to claim 2, wherein said inorganic acid is a boron-containing compound. 5. The electroless plating method according to claim 1, wherein the activation treatment liquid has a pH of 8-13. 6. The electroless plating method according to claim 1, wherein said electroless plating solution contains a reducing agent exhibiting catalytic activity for silver. 7. The electroless plating method according to claim 1, wherein the manganese ions have a manganese valence of 3 or more.