JP2000073191A - Solution for removing oxide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To harmlessly, safely and fast remove an oxide film without dissolving a base material itself by treating the surface of metal or an alloy by using a soln. containing substd. or unsubstd. aliphatic or aromatic phosphines and further containing a surfactant or the like. SOLUTION: This soln. to remove an oxide film is prepared by incorporating one or more kinds of phosphines or lower alkylphosphines expressed by the formula by about 0.1 to 50%. In the formula, X1, X2, X3 are each the same or different and are hydrogen, substd. or unsubstd. 1-10C alkyl groups or substd. or unsubstd. benzene rings, wherein substituents are hydroxy groups, carboxy groups, sulfo groups or amino groups and all X1, X2, X3 are not hydrogen at the same time. If necessary, a surfactant, acid, alkali, conductive salt, a pH controlling agent, a pH buffer, a pH indicator, a preventive agent against color change, a shielding complexing agent or the like are incorporated in the soln. As for the phosphines, tris(hydroxymethyl)phosphine, tris(2-hydroxyethyl) phosphine or the like are used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to surface treatment of metals or alloys, and more particularly to removal of oxide films and discoloration films.

[0002]

2. Description of the Related Art There are many manufacturing processes or storage processes in which it is necessary to remove an oxide film or a discolored film formed on the surface of a metal (including an alloy) to restore the original characteristics of a metal base material. For example, in a metal surface treatment step such as plating,
In order to ensure the close contact between the base metal and the plating film and to obtain a uniform and good film, a process called pickling or activation is required immediately before plating. In addition, for example, electrical circuits require a large number of contacts, such as copper or copper plated with silver or gold, and the oxide film formed on those surfaces has electrical resistance. It is necessary to remove those oxide films from time to time in order to increase the water content. In addition, for example, jewelry made of gold, silver, and their alloys requires not only a step of removing an oxide film in the manufacturing process, but also while being stored in a showcase or the like after the product is made. The so-called "refresh" for removing the oxide film is required because the color of the film becomes discolored and the commercial value decreases.

[0003] The removal of the oxide film referred to in the present application means not only the removal of the oxide film in a narrow sense where the surface of the base metal is bonded to oxygen, but also the bonding of elements such as sulfur and organic substances to the surface of the base material. The term is used to mean that the surface of the base metal that has been discolored due to adhesion or adsorption or the properties of the original metal surface of the base metal has changed is brought into a clean metal state.

[0004] These oxide films or discoloration films are generally dissolved and removed with an inorganic acid such as sulfuric acid, hydrochloric acid or nitric acid, an organic acid such as sulfonic acid or carboxylic acid, or a mixture thereof. For gold (alloy) and silver (alloy), aqua regia or a solution containing cyan or thiourea is often used.

[0005]

The solution for removing an oxide film as described above is dangerous because it contains a toxic or carcinogenic agent or is a strong acid or strong alkali. When a solution having a high acid concentration is used to remove a strong oxide film or to increase the removal rate, there is a problem that not only the oxide film but also the base material itself is dissolved. Inhibitors are sometimes used to suppress dissolution of the base material, but do not essentially solve the problem. It was an object of the present invention to develop a solution for removing an oxide film that is safe, quick, and capable of being treated so that the base material is substantially not dissolved.

[0006]

Means for Solving the Problems The inventors of the present application have made intensive studies to solve the above-mentioned problems in removing such an oxide film or a discolored film, and have found that substituted or unsubstituted aliphatic and / or unsubstituted aliphatic and / or discolored films. By using a solution containing an aromatic phosphine, it has been found that the oxide film can be removed very quickly and easily without substantially attacking the base material, and the above-mentioned problem has been solved. Further, since the solution exhibits an effect in a wide range from strong acidity to strong alkalinity, it has an advantage that the pH can be appropriately changed according to the purpose and used.

[0007]

That is, the present invention provides a solution for removing an oxide film, characterized in that the solution contains one or more of substituted or unsubstituted aliphatic and / or aromatic phosphines. Is what you do.

The phosphine used in the solution for removing an oxide film according to the present invention has the general formula (1)

Embedded image [Where X ₁ , X ₂ , and X ₃ may be the same or different and represent hydrogen, a substituted or unsubstituted C1 to C10 alkyl group, or a substituted or unsubstituted benzene ring; The substituted alkyl group or the substituent on the substituted benzene ring is one or more selected from a hydroxyl group, a carboxyl group, a sulfonic acid group and an amino group. However, X ₁ , X ₂ ,
All X ₃ are not simultaneously hydrogen. The phosphine represented by the general formula (2) is more preferably used.

Embedded image [Here, Y ₁ , Y ₂ , and Y ₃ may be the same or different, and may be one or two selected from an unsubstituted C1 to C3 alkyl group, a hydroxyl group, a carboxyl group, a sulfonic acid group, or an amino group. Represents a C1-C3 alkyl group substituted with at least one kind. A lower alkylphosphine represented by the formula:

Specific examples of phosphines which are preferably used include, for example, unsubstituted alkyl phosphines wherein the alkyl group is a methyl group, an ethyl group or a propyl group, and the hydrogen of the alkyl group is a hydroxyl group, a carboxyl group or a sulfonic acid group. Or substituted with an amino group, hydroxymethyl group, hydroxyethyl group, hydroxypropyl group, carboxymethyl group, carboxyethyl group, carboxypropyl group, sulfomethyl group, sulfoethyl group or sulfopropyl group, aminomethyl group, aminoethyl group or Examples thereof include a hydroxy lower alkyl phosphine having an aminopropyl group, a carboxy lower alkyl phosphine, a sulfo lower alkyl phosphine, and an amino lower alkyl phosphine.

[0010] Among them, trishydroxy lower alkyl phosphine composed only of a hydroxymethyl group, a hydroxyethyl group or a hydroxypropyl group in which one hydrogen of an alkyl group is substituted by a hydroxyl group is more preferred in view of cost and stability. Preferably, tris (3-hydroxypropyl) phosphine is most preferably used.

The solution for removing an oxide film of the present invention is most commonly used in the form of an aqueous solution, and in this case, hydroxyalkylphosphine, carboxyalkylphosphine, aminoalkylphosphine, sulfoalkylphosphine, and sulfonated arylphosphine are preferred. Used for The solution for removing an oxide film of the present invention may be used in the form of a solution of an organic solvent such as alcohols, ketones, and toluene. At this time, unsubstituted alkyl phosphine is preferably used. Of course, it may be in the form of, for example, a mixed solution of alcohol, ketone or the like and water.

The amount of the phosphine used in the solution for removing an oxide film according to the present invention is not particularly limited, and the amount of the phosphine is not limited.
1% to 50% is preferably used, but the processing speed decreases as the concentration decreases, and the stability of the solution decreases when the concentration is particularly high. Therefore, the concentration is more preferably 2% to 30%.
% Is commonly used. However, if the treatment may take a long time, for example, if the treatment is carried out by immersing overnight, it is not a problem that the treatment speed is slow, so the concentration is limited to the above concentration. Alternatively, a more dilute solution may be used.

The solution for removing an oxide film according to the present invention has a good effect of removing an oxide film or a discolored film against a wide variety of metals and alloys, but it has been difficult to treat with a safe solution. It is noteworthy that it has a very effective effect on relatively noble metals and their alloys, such as gold, rhodium, palladium, ruthenium, platinum, silver, copper and their alloys.

Further, the solution for removing an oxide film of the present invention has a good effect in all regions from strong acidity to strong alkalinity. Therefore, the acidity and alkalinity of the solution can be appropriately adjusted according to the type and situation of the base material and the purpose of use. It can be changed and used.

That is, for example, in the case of a product in which an iron material and a copper material are joined together, if the main purpose is to remove rust on the iron material, it is reasonable to use it in an acidic region. When the main purpose is to remove discoloration of the copper material, it is reasonable to use it in a neutral region.

When it is desired to remove discoloration or fogging of a jewelry or other jewelry in which a jewel or the like is embedded, it is reasonable to use the solution in a neutral region having little influence on the jewel.

When the pH is adjusted in this way, naturally, an acid or an alkali is added. For this purpose, for example, an inorganic acid such as sulfuric acid, hydrochloric acid or nitric acid, a sulfonic acid, a carboxylic acid or the like is used. Known acids and alkalis, such as organic acids, sodium hydroxide, potassium hydroxide, ammonia, and organic amines can be used.

In order to keep the set pH constant,
For example, in the case of sodium, potassium, ammonium or polybasic acids such as phosphoric acid, boric acid, hydrochloric acid, acetic acid, citric acid, and tartaric acid, known pH buffers such as acid salts thereof containing hydrogen ions are used. May be used alone or as a suitable mixture. Further, a pH indicator may be added in order to monitor a change in pH of the solution. A publicly known pH indicator may be used according to a usual usage according to a desired pH range.

The solution for removing an oxide film according to the present invention can be further used by adding a surfactant or a solvent. The addition of a surfactant or a solvent removes the surface of the object to be treated when the surface is contaminated with oils and fats, and helps the phosphine to uniformly contact the surface of the object to be treated, thereby improving the uniformity of the treatment. Increase and reduce processing time. In addition, it can help the solution penetrate into small gaps and the like, and can prevent processing unevenness.

As the surfactant used in the solution for removing an oxide film of the present invention, any of known surfactants can be used. The amount of the surfactant used depends on the general amount of the surfactant used. No problem.

The solution for removing an oxide film according to the present invention comprises:
Generally, the object to be treated is immersed in the solution to be used, but a method of applying the solution to the surface of the object to be treated by, for example, a brush or a spray may be employed, or a cloth or sponge may be used. A method of wiping the surface of the object to be treated by being included in a substance having an equal water absorption may be employed.

The solution for removing an oxide film according to the present invention comprises:
It is also used as an electrolytic degreasing or immersion degreasing solution in combination with a surfactant, an acid or an alkali or a conductive salt, and can remove oil and dirt and remove an oxide film at the same time.

Further, the solution for removing an oxide film according to the present invention may further contain a known discoloration inhibitor so that the clear surface obtained by removing the oxide film or the discolored film is less susceptible to re-oxidation or discoloration. For example, benzotriazoles, benzothiazoles and the like can be added and used.

In order to prevent the metal component from the removed oxide film from accumulating and reducing the removal rate, a known complexing agent such as EDTA or DTPA is further added as a masking complexing agent. Can be used.

As described above, the solution for removing an oxide film according to the present invention is, for example, a process called pickling or activation in a metal surface treatment process such as plating, for example, for repairing the function of a contact of an electric circuit, For example, it can be used in a wide range of applications from industrial use such as manufacturing process and functional property restoration process such as discoloration removal of jewelry, to commercial use such as restoration of jewelry, and further to general household use such as rust removal. .

[0025]

The present invention will be described in more detail with reference to the following Examples, which by no means limit the scope of the present invention. The concentration, composition, method of use, and the like can be arbitrarily changed as appropriate.

Example 1 An aqueous solution containing 7% of tris (3-hydroxypropyl) phosphine became cloudy when left for a long period of time.
K gold jewelry was dipped. The immersion for about 10 seconds completely removed the haze and restored the original brightness of the gold product. No evidence of base metal attack was found.

Example 2 An 18K gold jewelry that had been discolored by brazing was immersed in an aqueous solution containing 7% tris (3-hydroxypropyl) phosphine and adjusted to pH 7 with sulfuric acid. About 30
A second immersion removed the discoloration of the brazed part. No evidence of base metal attack was found.

Example 3 A solution containing 7% of tris (3-hydroxypropyl) phosphine and 0.2% of a nonionic surfactant (polyoxyethylene alkyl ether) and having a pH adjusted to 1 with sulfuric acid was added to an aqueous solution. An 18K gold jewelry that was discolored by the attachment was soaked. Discoloration was removed by immersion for about 20 seconds. No evidence of base metal attack was found.

Example 4 5% tris (hydroxymethyl) phosphine and 0.1%
% Nonionic surfactant (polyoxyethylene nonyl phenyl ether), and p with potassium dihydrogen phosphate
A silver jewelry whose color changed due to standing for a long time was immersed in an aqueous solution in which H was adjusted to 7. The immersion for about 10 seconds completely removed the fogging and restored the original brightness of the silver product.
No evidence of base metal attack was found.

Example 5 A solution containing 5% of tris (2-hydroxyethyl) phosphine and 0.1% of a nonionic surfactant (polyoxyethylene nonylphenyl ether) was brought to pH 7 with potassium dihydrogen phosphate. Rhodium-plated silver jewelry that had undergone discoloration over a long period of time was immersed in the adjusted aqueous solution. Clouding is completely removed by immersion for about 10 seconds,
The original shine of silverware has been restored. No evidence of base metal attack was found.

EXAMPLE 6 The pH was adjusted to 9 with sodium dihydrogen phosphate containing 10% of tris (3-hydroxypropyl) phosphine and 0.2% of an anionic surfactant (alkylsulfonate). The aqueous solution thus obtained was applied with a brush to a bus bar for heavy electricity which had been discolored due to long-term use. In about 30 seconds, the discoloration was completely removed, the original color tone of copper was restored, and the contact resistance was significantly improved. No evidence of base metal attack was found.

Example 7 A copper plate discolored when left for a long time in an aqueous solution containing 10% of tris (3-hydroxypropyl) phosphine and 10 g / l of ammonium chloride and adjusted to pH 11 with sodium hydroxide. Was immersed. In about 30 seconds, the discoloration was completely removed, and the original color tone of the copper was restored. No evidence of base metal attack was found.

Example 8 A solution containing 7% of tris (3-hydroxypropyl) phosphine and 0.2% of a nonionic surfactant (polyoxyethylene alkyl ester type), and adjusted to pH 7 with sodium dihydrogen phosphate. In the prepared aqueous solution, the iron material and the copper material were soldered and left in an atmosphere of a sulfide gas to immerse the sample in which discoloration occurred on the copper material. Discoloration on copper material is removed within 40 seconds,
No dissolution of the iron material was observed.

Example 9 An isopropyl alcohol solution containing 5% of tris (3-hydroxypropyl) phosphine and 5% of triethylphosphine was spray-coated on a gold-plated terminal portion of a printed circuit board used for a long time. After leaving for 1 minute, it was wiped off with a cloth. The contact resistance was significantly improved. No evidence of base metal attack was found.

Example 10 5% of tris (3-hydroxypropyl) phosphine and 0.1% of a nonionic surfactant (polyoxyethylene nonylphenyl ether) and 0,0
A brass plate that had been discolored by a sulfide gas was immersed in an aqueous solution containing 0.05% of 2-mercaptobenzothiazole and adjusted to pH 7 with potassium dihydrogen phosphate. About 2
Discoloration was completely removed by immersion for 0 seconds, and the original brightness of brass was restored. No evidence of base metal attack was found.

Example 11 After discoloration was caused by sulfide gas, using a silver spoon coated with salad oil as a cathode, 5% tris (3-hydroxypropyl) phosphine, 0.2% nonionic surfactant Electrolysis was performed at 2 A / dm ² in an aqueous solution (pH 7) containing an agent (polyoxyethylene nonylphenyl ether) and 30 g / l potassium dihydrogen phosphate. The discoloration was completely removed by electrolysis for about 20 seconds, and the original brightness of the silver product was restored. In addition, the oil component was completely removed and water was not repelled.

[0037]

The solution for removing an oxide film of the present invention does not require dangerous or toxic chemicals such as strong acid and cyanide.
The oxide film and the discolored film can be removed very quickly and easily without substantially attacking the base material. Further, the solution has the advantage that it can be used by appropriately changing the pH according to the purpose, since the solution exhibits the effect in a wide pH range.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Keigo Obata 8 stocks at Minami Futami 21 Futami-cho, Akashi-shi, Hyogo F-term (reference) 4K053 PA01 PA06 QA01 QA04 RA14 RA15 RA16 RA18 RA19 RA21 RA22 RA23 RA40 RA42 RA45 RA46 RA52 RA55 RA57 RA64 SA06 TA15 4K057 WA01 WB01 WB04 WE01 WE02 WE03 WE04 WE08 WE11 WE12 WE13 WE15 WE17 WJ05 WN01 WN02 WN09

Claims (4)

[Claims] 1. A compound of the general formula (1) [Where X ₁ , X ₂ , and X ₃ may be the same or different and represent hydrogen, a substituted or unsubstituted C1-C10 alkyl group, or a substituted or unsubstituted benzene ring; The group or the substituent of the substituted benzene ring is one or more selected from a hydroxyl group, a carboxyl group, a sulfonic acid group and an amino group. However, X ₁ , X ₂ ,
All X ₃ are not simultaneously hydrogen. ] A solution for removing an oxide film, comprising one or more of the phosphines represented by the formula: 2. The phosphine used is represented by the general formula (2): [Here, Y ₁ , Y ₂ , and Y ₃ may be the same or different, and may be one or two selected from an unsubstituted C1 to C3 alkyl group, a hydroxyl group, a carboxyl group, a sulfonic acid group, or an amino group. Represents a C1-C3 alkyl group substituted with at least one kind. The solution for removing an oxide film according to claim 1, wherein the solution is a lower alkylphosphine represented by the following formula: 3. The method according to claim 1, wherein the phosphine used is tris (hydroxymethyl) phosphine, tris (2-hydroxyethyl) phosphine or tris (3-hydroxypropyl) phosphine.
The solution for removing an oxide film according to the above. 4. The composition according to claim 1, further comprising one or more of a surfactant, an acid or alkali, a conductive salt, a pH adjuster, a pH buffer, a pH indicator, a discoloration inhibitor, and a masking complexing agent. The solution for removing an oxide film according to claim 1.