JP2023023770A - Electroless plating method - Google Patents

Abstract

To provide an electroless plating method capable of providing a high precipitation of plating without using a harmful chromic acid and capable of forming a plating film with a high adhesion to a resin body.SOLUTION: An electroless plating method for a resin material includes: (1) a step 1 of contacting a surface to be treated of the resin material with a surface control liquid; (2) a step 2 of contacting the surface to be treated of the resin material with the composition of a pre-treatment after the step 1; (3) a step 3 of contacting the surface to be treated of the resin material with a post treatment liquid containing an inorganic acid after the step 2; (4) a step 4 of contacting the surface to be treated of the resin material with a catalyst-imparting solution after the step 3; and (5) a step 5 of contacting the surface to be treated of the resin material with an electroless plating liquid after the step 4. The surface control liquid contains a solvent having an ether linkage. The composition of the pre-treatment contains a manganese ion of 10 mg/L or more and a monovalent silver ion of 10 mg/L or more.SELECTED DRAWING: None

Description

The present invention relates to an electroless plating method.

BACKGROUND ART In recent years, resin moldings have been used as automobile parts for the purpose of reducing the weight of automobiles. For this purpose, for example, ABS resin, PC/ABS resin, PPE resin, polyamide resin, etc. are used as resin moldings, and in order to impart a sense of quality and beauty, plating such as copper or nickel is applied. It is 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 resin materials such as resin substrates and resin moldings, after roughening the surface of the resin material by etching with chromic acid, neutralization and pre-dipping are performed as necessary. Next, a colloidal solution containing a tin compound and a palladium compound is used to apply an electroless plating catalyst, and then an activation treatment (accelerator treatment) for removing tin is performed to perform electroless plating and electroplating. A sequential method is used.

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, as a method of forming a plating film on a resin material, an aqueous solution containing metal activator molecular species is brought into contact with a part to be plated and etched, and a solution of a reducing agent capable of reducing the metal activator molecular species is used. A method of metal plating by contacting and contacting the part with an electroless plating solution has been proposed (see US Pat.

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. Since it is difficult to form a plated film on the above-mentioned resin molded product, especially PC/ABS resin, there is a problem that the plated film cannot be sufficiently formed and the adhesion of the plated film to the resin molded product is insufficient.

Therefore, there is a demand for the development of an electroless plating method capable of forming a plated film with high adhesion to a resin compact without using harmful chromic acid. .

Japanese Patent No. 4198799

The present invention has been made in view of the above problems, and can exhibit high plating deposition properties without using harmful chromic acid, and forms a plating film with high adhesion to a resin molded body. It is an object of the present invention to provide an electroless plating method capable of

As a result of intensive studies to achieve the above object, the present inventors have found that the surface to be treated of a resin material is treated with a surface conditioning liquid, a pretreatment composition, a post-treatment liquid containing an inorganic acid, a catalyst-imparting liquid, and a step of contacting with an electroless plating solution, the surface conditioning solution containing a solvent having an ether bond, and the pretreatment composition comprising 10 mg/L or more of manganese ions and 10 mg/L or more of monovalent silver. The inventors have found that the above object can be achieved by an electroless plating method containing ions, 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 bringing the treated surface of the resin material into contact with the surface conditioning liquid;
(2) step 2 of contacting the treated surface of the resin material with a pretreatment composition after step 1;
(3) step 3 of contacting the treated surface of the resin material with a post-treatment liquid containing an inorganic acid after step 2;
(4) step 4 of contacting the surface of the resin material to be treated with a catalyst-applying liquid after step 3;
(5) having a step 5 of contacting the treated surface of the resin material with an electroless plating solution after the step 4;
the surface conditioning liquid contains a solvent having an ether bond,
The pretreatment composition contains 10 mg/L or more of manganese ions and 10 mg/L or more of monovalent silver ions.
An electroless plating method characterized by:
2. Item 2. The electroless plating method according to item 1, wherein the manganese ions have a manganese valence of 3 or more.
3. Item 3. The electroless plating method according to Item 1 or 2, wherein the inorganic acid is at least one selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, hydrofluoric acid, and boric acid.
4. Item 4. The electroless plating method according to any one of Items 1 to 3, wherein the catalyst-imparting solution contains 0.1 mg/L or more of a palladium compound and does not contain a tin compound.
5. Item 5. The electroless plating method according to any one of Items 1 to 4, wherein the resin material is an alloyed resin of a styrene resin and a polycarbonate (PC) resin.

The electroless plating method of the present invention can exhibit high deposition properties of plating without using harmful chromic acid, and can form a plating film with high adhesion to a resin molded body.

The present invention will be described in detail below.

1. Electroless Plating Method The electroless plating method of the present invention is a method for electroless plating a resin material, comprising (1) step 1 of bringing the treated surface of the resin material into contact with a surface conditioning liquid; (3) after step 2, contacting the surface of the resin material to be treated with a post-treatment liquid containing an inorganic acid; (4) after step 3, a step 4 of bringing the treated surface of the resin material into contact with the catalyst applying solution; and (5) after step 4, the resin material is covered with the electroless plating solution. A step 5 of contacting the surface to be treated, wherein the surface conditioning liquid contains a solvent having an ether bond, and the pretreatment composition contains 10 mg/L or more of manganese ions and 10 mg/L or more of monovalent silver ions. It is characterized by containing

The electroless plating method of the present invention has the above steps 1 to 5, and the surface conditioning liquid used in step 1 contains a solvent having an ether bond. A sufficient plating film can be formed even on a resin molding on which it is difficult to form a film.

Further, in the electroless plating method of the present invention, the pretreatment composition used in step 2 contains 10 mg/L or more of manganese ions and 10 mg/L or more of monovalent silver ions. A high etching power can be exhibited with respect to the surface, and the application of the silver catalyst becomes sufficient.

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 2 contains manganese ions and monovalent silver ions. can be adsorbed. Then, the manganese residue is removed by immersion in a post-treatment liquid containing an inorganic acid, and then substitution of silver for palladium occurs by immersion in a catalyst liquid containing palladium ions. Then, by bringing the surface to be treated into contact with the electroless plating solution, a plating film can be sufficiently formed on the surface to be treated, and a plating film with good adhesion can be formed.

That is, the electroless plating method of the present invention does not use harmful chromic acid, and exhibits high deposition of plating even on a resin molded body such as PC/ABS resin on which it is difficult to form a plating film. It is possible to form a plating film with high adhesion.

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 done. 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. Alloyed resins of the above styrene-based resins and polycarbonate (PC) resins (for example, alloyed resins containing about 30 to 70% by mass of PC resin) can also be suitably used. In particular, an alloyed resin (PC/ABS resin) of ABS resin and polycarbonate resin, for example, PC/ABS resin, which is an alloyed resin containing about 30 to 70% by mass of PC resin, can be preferably 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. Among these, the electroless plating method of the present invention can exhibit high deposition properties of plating even with PC/ABS resin, which is particularly difficult to form a plating film, and forms a plating film with high adhesion. be able to.

The shape, size, etc. of the resin material are not particularly limited, and according to the electroless plating method of the present invention, a good plating film excellent in decorativeness, physical properties, etc. can be formed even on a large resin material having a large surface area. can be formed. 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 surface conditioning liquid.

The surface conditioning liquid used in step 1 contains a solvent having an ether bond. 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 surface conditioning liquid containing a solvent having an ether bond, thereby plating a resin molded article, particularly a PC/ABS resin or the like. A sufficient plating film can be formed even on a resin molding on which it is difficult to form a film.

The solvent having an ether bond is not particularly limited as long as it has an ether bond in its molecule and can be used as a solvent. Examples of solvents having such an ether bond include glycol ether solvents, cyclic ether solvents, aromatic ring-containing ether solvents, and the like.

Glycol ether solvents include ethylene glycol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether (PGME; also known as 1-methoxy-2-propanol), propylene glycol dimethyl ether, propylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and diethylene glycol monomethyl. Ether, triethylene glycol monoethyl ether, methoxymethylbutanol, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol mono Phenyl ether, diethylene glycol monoethyl ether, diethylene glycol monoethyl ether acetate and the like.

Cyclic ether solvents include tetrahydrofuran, tetrahydropyran, propylene carbonate and the like.

Diphenyl ether, anisole (methylphenyl ether), etc. are mentioned as an aromatic ring containing ether-type solvent.

Among the above solvents having an ether bond, ethylene glycol, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether acetate, and propylene carbonate are preferred, and ethylene glycol mono Butyl ether, diethylene glycol monoethyl ether acetate, and propylene carbonate are more preferred.

The solvents having an ether bond may be used singly or in combination of two or more.

The content of the solvent having an ether bond in the surface conditioning liquid is not particularly limited. The content is preferably 5 g/L or more, more preferably 10 g/L or more, still more preferably 50 g/L or more, and particularly preferably 100 g/L or more. The content is preferably 900 g/L or less, more preferably 850 g/L or less, still more preferably 500 g/L or less, and particularly preferably 300 g/L or less. When the lower limit of the content of the solvent is within the above range, it is possible to sufficiently form a plating film with higher adhesion on the resin molding. In addition, when the upper limit of the content of the solvent is within the above range, it is possible to obtain a film appearance that is even more excellent in decorativeness.

In the surface conditioning liquid, the above solvent is preferably dissolved in a solvent such as water. That is, the surface conditioning liquid is preferably an aqueous solution in which a solvent having an ether bond is dissolved in water.

The surface conditioning liquid may further contain other additives in addition to the solvent having an ether bond. Such other additives include surfactants and the like.

The method of bringing the treated surface of the resin material into contact with the surface conditioning 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 surface conditioning liquid, a method of spraying the surface conditioning liquid 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 surface conditioning liquid is preferable because it is more excellent in contact efficiency.

The temperature of the surface conditioning liquid in step 1 is not particularly limited, and is preferably 20 to 100.degree. C., more preferably 30 to 90.degree. C., and even more preferably 40 to 80.degree. By setting the lower limit of the temperature of the surface conditioning liquid within the above range, it is possible to sufficiently form a plating film with high adhesion on the resin molding. Further, by setting the upper limit of the temperature of the surface conditioning liquid within the above range, it is possible to obtain a film appearance that is even more excellent in decorativeness.

The contact time between the surface conditioning liquid and the treated surface of the resin material in step 1 is preferably 10 seconds to 60 minutes, more preferably 30 seconds to 30 minutes, and even more preferably 1 to 15 minutes. By setting the lower limit of the contact time within the above range, it is possible to sufficiently form a highly adhesive plating film on the resin molding. 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 1 described above, the surface to be treated of the resin material can be brought into contact with the surface conditioning liquid.

In the pretreatment method of the present invention, a degreasing treatment may be performed 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 performed in the field of electroless plating.

(Step 2)
Step 2 is a step of bringing the treated surface of the resin material into contact with the pretreatment composition after step 1 above.

The pretreatment composition used in step 2 contains 10 mg/L or more of manganese ions and 10 mg/L or more of monovalent silver ions.

Since the pretreatment composition used in step 2 contains a specific amount of manganese ions and a specific amount of monovalent silver ions, a high etching power can be exhibited with respect to the treated surface of the resin material, Application of the silver catalyst becomes sufficient.

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, since the pretreatment composition contains manganese ions and monovalent silver ions, it is possible to adsorb silver on the surface of the resin material by bringing the surface to be treated of the resin material into contact with the composition. Then, the manganese residue is removed by immersion in a post-treatment liquid containing an inorganic acid, and then substitution of silver for palladium occurs by immersion in a catalyst liquid containing palladium ions. Then, by bringing the surface to be treated into contact with an electroless plating solution, a plated film with good adhesion can be formed on the surface to be treated.

In addition, since the pretreatment composition contains manganese ions and monovalent silver ions, etching of the surface to be treated and application of the silver catalyst can be performed simultaneously by bringing the surface to be treated of the resin substrate into contact with the pretreatment composition. .

(manganese ion)
Manganese ions 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 content of manganese ions 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, the deposition property of plating is even better for resin materials formed of resins such as alloyed resins of styrene resin and polycarbonate (PC) resin, on which plating is difficult to deposit, and the plating film is formed. Silver sulfate (I) is preferred because it is more difficult to reduce adhesion.

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 and phosphoric acid are preferred, and sulfuric acid is more preferred, in terms of more excellent 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 is not particularly limited. For example, the total acid concentration is preferably 100-1800 g/L, more preferably 800-1700 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 of the present invention 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.

The pretreatment composition is preferably acidic. Since the pretreatment composition is acidic, the etching treatment of the resin material becomes more satisfactory. The pH of the pretreatment composition is preferably 2 or less, more 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 2 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 2, 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 step 2 of the electroless plating method of the present invention.

Through step 2 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.

(Step 3)
Step 3 is a step of bringing the treated surface of the resin material into contact with a post-treatment liquid containing an inorganic acid after step 2 above. Manganese adhering to the surface of the resin material is removed by having the step 3 after the step 2 in the electroless plating method.

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 is preferably 1 to 1000 g/L, more preferably 5 to 750 g/L, and more preferably 10 to 500 g/L.

The post-treatment method is not particularly limited, and for example, the resin material pretreated in step 2 may be immersed in a post-treatment liquid having a liquid temperature of about 15 to 50° C. for about 1 to 10 minutes. The post-treatment can further improve the depositability and appearance of the formed plating film.

Through Step 3 described above, the treated surface of the resin material is brought into contact with the post-treatment liquid containing the inorganic acid.

(Step 4)
Step 4 is a step of bringing the treated surface of the resin material into contact with the catalyst-imparting liquid after step 3 above. Through step 4, a catalyst can be applied to the surface of the resin material.

As the catalyst-imparting liquid, a known catalyst-imparting liquid generally used for imparting a catalyst for electroless plating can be used. Examples of such a catalyst-imparting liquid include a catalyst-imparting liquid containing a catalytic metal-containing compound.

The catalytic metal-containing compound is not particularly limited as long as it is used for electroless plating, and examples thereof include palladium compounds and platinum compounds. Among these, a palladium compound is preferable because it is easier to form an electroless plating film on a resin material.

The palladium compound is preferably one that can be easily dissociated in water to release palladium ions, such as palladium chloride (PdCl ₂ ) and palladium sulfate (PdSO ₄ ).

Palladium in the catalyst-imparting liquid preferably exists as palladium ions, that is, in an ionic state, and more preferably has a valence of +2.

The lower limit of the content of the palladium compound in the catalyst application liquid is preferably 0.01 mg/L or more, more preferably 0.1 mg/L or more, still more preferably 1 mg/L or more, and particularly preferably 10 mg/L or more. Further, the upper limit of the content of the palladium compound is preferably 2000 mg / L, more preferably 0.05 to 1500 mg / L, preferably 0.1 to 1000 mg / L or less, more preferably 1500 mg / L or less, 1000 mg / L is more preferred, and 750 mg/L or less is particularly preferred.

The catalyst-imparting liquid may contain a tin compound. As the tin compound, stannous compounds are preferred, and examples of such stannous compounds include those that can be easily dissociated in water to release stannous ions. Examples of the stannous compound include stannous chloride and stannous sulfate.

In the electroless plating method of the present invention, it is not always necessary to use a palladium-tin colloidal solution in step 4 as in the conventional catalyst application step, and the catalyst application solution preferably does not contain a tin compound. Since the catalyst-imparting liquid does not contain a tin compound, the activation treatment (accelerator treatment) step for removing tin can be omitted, and the steps for electroless plating can be shortened. In addition, since palladium ions are imparted by a substitution reaction with silver, two-color molded products using ABS resin and polycarbonate resin or PC/ In two-color molded products using ABS resin and polycarbonate resin, the adsorption of the catalyst to the polycarbonate resin is suppressed, so it is suitable for selective plating on these two-color molded products. In addition, adsorption of the catalyst to the surface of the jig is suppressed, and deposition of the plating film on the surface of the jig is suppressed. As a result, when the jig is repeatedly used to form an electroless plating film, the plating film deposited on the surface of the jig peels off in granular form and is incorporated into the electroless plating film on the surface of the resin material in each process. The unevenness of the electroless plated film on the surface of the resin material that is caused by the coating is suppressed. From the above viewpoint, the catalyst-imparting liquid preferably contains 0.1 mg/L or more of a palladium compound and does not contain a tin compound.

The method for bringing the treated surface of the resin material into contact with the catalyst-imparting 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 catalyst-imparting liquid, a method of spraying the catalyst-imparting liquid onto the treated surface of the resin material, and the like. Among these methods, the method of immersing the resin material in the catalyst-imparting liquid is preferable because it is more excellent in contact efficiency.

The temperature of the catalyst-imparting liquid in step 4 is not particularly limited, and is preferably 30 to 90°C, more preferably 40 to 80°C, even more preferably 50 to 70°C.

In step 4, the contact time between the catalyst-imparting liquid and the treated surface of the resin material is not particularly limited, and may be about 1 to 10 minutes.

Through step 4 described above, the surface of the resin material to be treated is brought into contact with the catalyst-applying liquid, and the catalyst is applied to the surface of the resin material to be treated.

(Step 5)
Step 5 is a step of bringing the treated surface of the resin material into contact with the electroless plating solution after step 4 above.

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, and electroless gold plating solution.

Examples of the electroless nickel plating solution include plating solutions containing nickel sulfate or its hydrate. Moreover, examples of the electroless copper plating solution include a plating solution containing copper sulfate, a hydrate thereof, or the like.

The electroless plating solution may contain a reducing agent from the viewpoint of improving the depositability of the plating. The reducing agent is not particularly limited and includes dimethylamine borane, formalin, glyoxylic acid, tetrahydroboric acid, hydrazine, hypophosphite, erythorbic acid, ascorbic acid, hydroxylamine sulfate, hydrogen peroxide, glucose and the like. Among these, dimethylamine borane, formalin, glyoxylic acid, tetrahydroboric acid, and hydrazine are preferable in that they exhibit catalytic activity for silver and have better plating deposition properties.

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

The content of the reducing agent in the electroless plating solution is not particularly limited, and is preferably 0.01 to 100 g/L, more preferably 0.1 to 50 g/L, even more preferably 1 to 30 g/L. 20 g/L is particularly preferred. 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.

The electroless plating solution may contain an organic acid complexing agent from the viewpoint of improving the deposition stability of the plating solution. The organic acid complexing agent is not particularly limited and includes 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, and alanine. , aspartic acid, glutamic acid, iminodiacetic acid, nitrilotriacetic acid, fumaric acid, or salts thereof. Among these, formic acid, oxalic acid, glycolic acid, tartaric acid, citric acid, maleic acid, or salts thereof are preferable in terms of better plating deposition properties.

The above organic acid complexing agents may be used singly or in combination of two or more.

The concentration of the organic acid complexing agent in the electroless plating solution is not particularly limited, and is preferably from 0.1 to 500 g/L, more preferably from 1 to 100 g/L, and even more preferably from 2 to 50 g/L.

The electroless plating solution may contain an alkaline compound from the viewpoint of improving the depositability of plating. Alkaline compounds include sodium hydroxide, potassium hydroxide, ammonia and the like.

The above alkaline compounds may be used singly or in combination of two or more.

The concentration of the alkaline compound in the electroless plating solution is not particularly limited, and is preferably about 1 to 50 g/L, more preferably 5 to 15 g/L.

The electroless plating solution may contain a complexing agent from the viewpoint of improving the depositability of the plating.

The complexing agent is not particularly limited, and known complexing agents used in electroless plating solutions can be used. Examples of such complexing agents include ethylenediaminediacetic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, their ammonium salts, potassium salts, sodium salts and the like, and amino acids such as ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid. Examples include polycarboxylic acids and their sodium salts, potassium salts, ammonium salts and the like.

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

The concentration of the complexing agent in the electroless plating solution is not particularly limited, and is preferably about 1 to 50 g/L, more preferably 5 to 40 g/L, even more preferably 10 to 30 g/L.

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.

In the electroless plating method of the present invention, step 5 may be repeated two or more times, if necessary. By repeating step 5 twice or more, two or more layers of electroless plated films are formed.

Through step 5 described above, the treated surface of the resin material is brought into contact with the electroless plating solution, and electroless plating is formed on the treated surface of the resin material.

The electroless plating method of the present invention may further include an electroplating step after step 5.

In the electroplating step, after the above step 5, if necessary, the substrate may be subjected to an activation treatment with an aqueous solution of acid, 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 dm 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 ( A flat plate (10 cm×5 cm×0.3 cm, surface area: about 1 dm ² ) of TC25M (trade name, manufactured by Co., Ltd.) was prepared, and an electroless plating film was formed by the following method.

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

Next, according to the formulations shown in Table 1, the surface conditioning liquid, the pretreatment composition, the post-treatment liquid, the catalyst-imparting liquid, and the electroless plating liquid 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.

Using each liquid prepared as described above, electroless plating was applied to a test piece under the following conditions in order from process 1 to process 5 under the following conditions. In Comparative Example 1, Step 1 was not performed, and in Comparative Example 5, Step 3 was not performed.

(Step 1)
Immersion in surface conditioning liquid: immersion temperature 55°C, immersion time 3 minutes

(Step 2)
Immersion in pretreatment composition: immersion temperature 75°C, immersion time 20 minutes

(Step 3)
Immersion in post-treatment liquid: immersion temperature 40°C, immersion time 1 minute

(Step 4)
Immersion in catalyst-imparting liquid: immersion temperature 60°C, immersion time 3 minutes

(Step 5)
Immersion in electroless plating solution: immersion temperature 35°C, immersion time 5 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 is made in the plating film, and a tensile tester (manufactured by Shimadzu Corporation, Autograph AGS-J 1kN) is used to pull the plating film in a direction perpendicular to the surface of the resin material, peeling it off. Strength was measured.

Table 1 shows the results.

In Table 1, in Comparative Example 4, a pretreatment composition was prepared by the following method in order to dissolve Ag(II) when preparing the pretreatment composition. That is, after dissolving additives other than the Mn salt in pure water, anodic electrolysis was performed using a Pt electrode under the condition of 1 Ah/L to generate Ag(II). Mn salt was then added at a given concentration.

Claims (5)

An electroless plating method for a resin material,
(1) Step 1 of bringing the treated surface of the resin material into contact with the surface conditioning liquid;
(2) step 2 of contacting the treated surface of the resin material with a pretreatment composition after step 1;
(3) step 3 of contacting the treated surface of the resin material with a post-treatment liquid containing an inorganic acid after step 2;
(4) step 4 of contacting the surface of the resin material to be treated with a catalyst-applying liquid after step 3;
(5) having a step 5 of contacting the treated surface of the resin material with an electroless plating solution after the step 4;
The surface conditioning liquid contains a solvent having an ether bond,
The pretreatment composition contains 10 mg/L or more of manganese ions and 10 mg/L or more of monovalent silver ions.
An electroless plating method characterized by: 2. The electroless plating method according to claim 1, wherein the manganese ions have a manganese valence of 3 or more. 3. The electroless plating method according to claim 1, wherein said inorganic acid is at least one selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, hydrofluoric acid and boric acid. 4. The electroless plating method according to claim 1, wherein said catalyst-imparting liquid contains 0.1 mg/L or more of a palladium compound and does not contain a tin compound. 5. The electroless plating method according to claim 1, wherein said resin material is an alloyed resin of styrene resin and polycarbonate (PC) resin.