JP2011149071A - Composite plating solution having diamonds particle dispersed therein, and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a composite plating solution which makes diamonds particles having the average particle size of 1-1,000 nm uniformly dispersed and codeposited in a plated metal film, and can impart a function of abrasion resistance, self-lubricating properties and the like to the plated metal film. <P>SOLUTION: The method for producing the composite plating solution having the diamonds particles stably dispersed therein includes: preparing a dispersion liquid in which diamond particles having the average particle size of 1-1,000 nm, onto which a hydrophilic polymer or an ionic functional group has been introduced, are dispersed together with an ionic or nonionic surface active agent; and adding the dispersion liquid to a metal-plating solution. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a composite plating solution in which diamond fine particles are uniformly dispersed and a method for producing the same. More specifically, the present invention relates to a composite plating solution in which diamond fine particles introduced with a hydrophilic polymer or an ionic functional group are dispersed together with a surfactant in a metal plating solution, and a method for producing the same.

  Nanodiamond, which is a fine diamond particle, is artificially produced by the impact compression method or the static pressure method, and the form obtained by the production method is different. Different types of nanodiamond such as polycrystal, single crystal, and cluster are known. Yes. Polycrystalline nanodiamond has a spherical structure and is therefore considered a material suitable for a sliding surface between solids.

  The polycrystalline nanodiamond is a sintered body having a primary particle size of 5 to 20 nm, but it is difficult to stably exist as a primary particle, and a large aggregate of about 50 to 7,500 nm It exists. Therefore, such nanodiamond has been used by being dispersed in a liquid when used industrially.

  When using fine particles for the plating treatment, a method of using fine particles dispersed in an aqueous solvent is generally used. For example, a composite plating bath in which fine particles such as fluororesin, nylon, polyethylene, graphite, fluorinated graphite, molybdenum disulfide, and boron nitride are dispersed in a metal plating bath is known. By immersing the object to be plated in such a composite plating bath and performing composite plating, a metal film is chemically deposited on the surface of the object to be plated, and fine particles are co-deposited in the metal film, and the fine particles are deposited in the metal matrix. A dispersed composite plating film can be formed. The formed composite plating film will have the properties of dispersed fine particles as well as various physical properties of the plated metal. Depending on the type of fine particles to be dispersed and co-deposited, various excellent properties such as low friction, wear resistance, hardness, etc. Properties can be imparted to the plating film.

  However, as fine particles to be dispersed, carbon-based materials such as nanodiamonds, fine particles such as fluorine-based resins, ceramics, etc. are used for plating treatment, which is strong in water repellency and hydrophobicity and can be dispersed in a metal plating bath as it is. Therefore, it is very difficult to disperse and eutect the fine particles uniformly in the plating film.

  Conventionally, a method of dispersing fine particles in a plating bath using a surfactant as a dispersion aid has been used. As surfactants used as dispersion aids, there are known cationic surfactants, amphoteric surfactants and nonionic surfactants that exhibit a cationic property corresponding to the pH of the plating bath. Patent Document 1 describes that composite plating is performed by adding a nonionic dispersant to a plating solution mixed with diamond powder and dispersing the diamond powder in the plating solution.

  As a method that does not use a surfactant, for example, in Patent Document 2, a plating film in which diamond fine particles are dispersed by immersing a substrate while stirring with a gas containing oxygen in a plating bath in which diamond fine particles are suspended is used. A method of forming is described. Patent Document 3 describes a method of performing composite plating with a dispersion liquid in which a cationic functional group is introduced and dispersed in nanodiamond using a polyethylene glycol unit-containing polymer azo polymerizer (AZOPEG) as an introduction agent. Has been.

JP-A-8-337883 JP 2006-225730 A JP 2008-150250 A

  The polycrystalline nanodiamond obtained by the impact compression method has primary particles as small as 5 to 20 nm, but the surface of the nanodiamond is fused with non-graphitic, graphite film, etc. It is manufactured and sold as a secondary or tertiary aggregate of 7,500 nm.

  When commercially available nanodiamonds are dispersed in the plating solution, even if a surfactant is added, the particles are likely to aggregate, and the aggregated particles are precipitated, so that it is very difficult to obtain a stable dispersion. There was a problem that nanodiamonds aggregated (segregated) on the surface of the plating film that was plated in a state where nanodiamonds were not stably dispersed.

  In order to deal with such problems, it has been proposed to crush nanodiamond aggregates by an ultrasonic dispersion method, a bead mill dispersion method, or the like. By using such a dispersion method, a dispersion liquid having an average particle diameter of nano-diamonds of 10 nm to several hundred nm can be obtained. However, since nano-diamonds are affected by metal ions in the plating solution, nano-diamonds are re-aggregated and precipitated. Will occur.

  Moreover, in the conventional composite plating process using nanodiamonds, nanodiamonds having an average particle size of several nanometers to several hundred nanometers were dispersed in a plating solution to obtain a composite plating film. Since the concentration of dispersed nanodiamond was dilute, the content of nanodiamond co-deposited in the composite plating film was about several percent. Therefore, a composite plating film that sufficiently exhibits the characteristics of nanodiamonds cannot be obtained.

  Therefore, an object of the present invention is to provide a composite plating solution in which diamond fine particles are stably dispersed and a method for producing the same.

  In the method for producing a composite plating solution according to the present invention, a dispersion in which diamond fine particles into which a hydrophilic polymer or an ionic functional group has been introduced is dispersed together with an ionic or nonionic surfactant is added to the metal plating solution. Thus, a composite plating solution in which diamond fine particles are stably dispersed is manufactured. Further, the diamond fine particles have an average particle diameter of 1 nm to 1000 nm. Further, the surfactant is a homopolymer or copolymer surfactant having a molecular weight of 30,000 to 200,000. Furthermore, the metal plating solution contains one or more metal ions selected from the group consisting of nickel ions, cobalt ions, copper ions, gold ions, iron ions, palladium ions, platinum ions, tin ions and rhodium ions. It is characterized by including.

  In the composite plating solution according to the present invention, diamond fine particles having an average particle diameter of 1 nm to 1000 nm and an ionic or nonionic surfactant in which a hydrophilic polymer or an ionic functional group is introduced are uniformly contained in the metal plating solution. It is distributed. Further, the diamond fine particles have a concentration of 0.1 g / liter to 20 g / liter. Further, the surfactant is a homopolymer or copolymer surfactant having a molecular weight of 30,000 to 200,000.

  The composite plating method according to the present invention is characterized by forming a composite plating film in which the diamond fine particles are uniformly dispersed in a metal matrix by performing a plating treatment on the substrate surface using the composite plating solution. And

  The present invention has the above-described configuration, whereby diamond fine particles into which a hydrophilic polymer or an ionic functional group is introduced are dispersed in a metal plating solution together with an ionic or nonionic surfactant, and diamond A composite plating solution in which fine particles are uniformly dispersed in a stable state can be obtained.

It is a graph which shows the measurement result of the zeta potential regarding a composite plating solution. It is a graph which shows the measurement result of the particle size distribution regarding a composite plating solution. 2 is an enlarged SEM photograph of a cross section of the composite plating film of Example 1. FIG. 4 is an enlarged SEM photograph of a cross section of the composite plating film of Example 2. FIG.

  The metal plating solution used in the present invention is not particularly limited, but is selected from the group consisting of nickel ions, cobalt ions, copper ions, gold ions, iron ions, palladium ions, platinum ions, tin ions and rhodium ions. The thing containing a seed | species or 2 or more types of metal ions can be used, The metal plating solution containing a nickel ion is mentioned as an especially preferable thing.

  As the diamond fine particles used in the present invention, those having an average particle diameter of 1 nm to 1000 nm, preferably 10 nm to 1000 nm, particularly preferably 10 nm to 200 nm may be used. As such diamond fine particles, those of a polycrystalline type, a single crystal type, and a cluster type that are usually available can be used. In order to obtain a composite plating film having excellent sliding characteristics, a film having a small particle size may be used.

  In order to uniformly disperse the diamond fine particles in the metal plating solution, a hydrophilic polymer or an ionic functional group is introduced on the surface of the diamond particle. For example, in the case of a cationic functional group, protons are easily generated in an acidic region. An amino group, a thiol group, a hydroxyl group, a phosphine group and the like which are bonded to each other to form onium. Among these, an amino group that is most likely to form onium is preferable, and an amidine skeleton having two amino groups is more preferable.

  Therefore, the azo radical initiator to be reacted with the diamond fine particles preferably has an amidine skeleton. Amidine may be hydrochloride or cyclic. Specifically, 2,2′-azobis (2-methyl-N-phenylpropionamidine) dihydrochloride, 2,2′-azobis [N- (4-chlorophenyl) -2-methylpropionamidine] dihydrochloride Salt, 2,2′-azobis [N- (4-hydroxyphenyl) -2-methylpropionamidine] dihydrochloride, 2,2′-azobis [2-methyl-N- (phenylmethyl) propionamidine] dihydrochloride Salt, 2,2′-azobis [2-methyl-N- (2-propenyl) propionamidine] dihydrochloride, 2,2′-azobis (2-methylpropionamidine) dihydrochloride, 2,2′-azobis [N- (2-hydroxyethyl) -2-methylpropionamidine] dihydrochloride, 2,2′-azobis [2- (5-methyl-2-imidazolin-2-yl) propane Dihydrochloride, 2,2'-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis [2- (4,5,6,7-tetrahydro-1H- 1,3-diazepin-2-yl) propane] dihydrochloride, 2,2′-azobis [2- (3,4,5,6-tetrahydropyrimidin-2-yl) propane] dihydrochloride, 2,2 '-Azobis [2- (5-hydroxy-3,4,5,6-tetrahydropyrimidin-2-yl) propane] dihydrochloride, 2,2'-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} dihydrochloride, 2,2′-azobis [2- (2-imidazolin-2-yl) propane] and the like. These are commercially available and can be easily obtained.

  In order to produce an aqueous dispersion in which diamond fine particles having ionic functional groups introduced therein are dispersed, the diamond fine particles are reacted with an azo radical initiator in an aqueous solvent. What is necessary is just to mix a diamond fine particle and an azo radical initiator in an aqueous solvent, and to start radical reaction by heating or light irradiation. In the case of heating, it is sufficient to heat to 50 ° C. or more, preferably 65 to 75 ° C., and the reaction is completed in several tens of hours. The rate of reaction depends on the amount of the azo radical initiator, and it is preferable to use an azo initiator in an amount of 0.1 to 5 times the weight of the diamond fine particles. If the amount of the azo initiator exceeds 5 times, the amount of organic matter introduced into the diamond fine particles will not increase, and if it is less than 0.1 times the amount of organic matter introduced into the diamond fine particles is small and the dispersibility becomes insufficient. .

  The aqueous solvent is water or a mixture of water and a water-soluble solvent, and usually water may be used. When the azo radical initiator to be used does not dissolve in water, a water-soluble solvent can be appropriately mixed and used. Examples of the water-soluble solvent include alcohols such as methanol and ethanol, aliphatic polyols such as ethylene glycol, glycerin and low molecular weight polyethylene glycol, nitriles such as acetonitrile, N, N-dimethylformamide, N, N-dimethylacetamide. Amides such as N-methyl-2-pyrrolidone, sulfur-containing solvents such as dimethyl sulfoxide, dimethyl sulfone and sulfolane, and phosphorus-containing solvents such as hexamethylphosphoric triamide.

  The concentration of the diamond fine particles during the reaction is preferably 1 to 20% by weight, more preferably 5 to 10% by weight. When the concentration is higher than 20% by weight, the diamond fine particles aggregate, and the reaction between the aggregated diamond fine particles and the azo radical initiator becomes insufficient, making it difficult to introduce an ionic functional group. If it is less than 1% by weight, the concentration of diamond fine particles in the composite plating solution is lowered and the amount of diamond fine particles in the composite plating film is reduced.

  The aqueous dispersion of diamond fine particles obtained by the above method can be added to the metal plating solution as it is, but a treatment such as separation and washing is performed to remove unreacted azo radical initiators and excess salts. Preferably it is done. As the separation method, methods such as filtration and centrifugation are used. As the filter medium, a membrane filter of about 0.1 μm is preferable because of little separation loss. In the case of washing, demineralized water is usually used, but a water-soluble organic solvent may be appropriately mixed so that the remaining organic substances such as the azo radical initiator can be easily removed. Moreover, in order to adjust pH, various salts can also be dissolved and used.

  In order to suppress reaggregation of diamond fine particles in the aqueous dispersion, it is preferable to adjust the aqueous dispersion to a pH in the range of 3 to 8. In the case of a strong acid or base liquid, the charge on the surface of the diamond fine particles is neutralized by a counter ion, and dispersion stability due to charge repulsion is inhibited. Examples of the pH adjuster include monohydrogen phosphate, dihydrogen phosphate, hydrogen carbonate, carbonate, hydroxide, and the like, and alkali metal salts, alkaline earth metal salts, ammonium salts, and the like are used. You can also.

  In addition, by using a hydrophilic polymer as a functional group to be introduced on the surface of the diamond fine particles, the steric repulsion force due to the polymer chain on the surface of the fine particles can be increased, and the diamond fine particles can be stably dispersed.

In this case, both ends of the azo radical initiator can be converted from a hydroxyl group to a Cl (chlorine) end, and then a polymer chain can be imparted to the resulting compound. For example, a polyethylene glycol (PEG) residue, a polydimethylsiloxane (PDMS) residue, etc. are mentioned. The conversion from a hydroxyl group to a Cl terminal can be widely applied to known reaction conditions for acid chloride reaction. The subsequent reaction with the polymer is a general dehydrochlorination reaction, and it is usually advantageous to carry out the reaction in the presence of a basic compound. Here, as the PEG residue, specifically,
_{- (CH 2 CH 2 O)} n - (n is about 4 or more, preferably about 10 or more integer)
Is mentioned. PDMS residues include
_{- [Si (CH 3) 2} -O] m - (m is about 3 or more, preferably 40 or more integer)
(See JP 2006-219591 A).

  In addition, diamond fine particles are surface treated under dry conditions with an amino group-containing silane coupling agent or amino group-containing silicone oil to introduce amino groups on the surface, and Michael addition of methyl acrylate is added to the introduced amino groups. It is also possible to form a polyamine dendrimer on the surface of the diamond fine particles by repeating the reaction and terminal amination with diamine by repeating under dry conditions (see JP 2001-106940 A).

  Even if the diamond fine particles introduced with the hydrophilic polymer or ionic functional group described above are added to the metal plating solution as they are, they are affected by the strong ionic strength of electrolyte ions such as nickel ions in the metal plating solution. The electrostatic repulsive force acting between the fine particles is canceled out, causing aggregation and precipitation.

  Therefore, it is preferable to add a surfactant as a dispersant in order to suppress such aggregation and precipitation of the diamond fine particles and stably disperse the diamond fine particles in the metal plating solution. Examples of the surfactant to be added include anionic surfactants such as anionic and cationic surfactants, and nonionic surfactants. For example, in the case of an ionic surfactant, there are alkylbenzene sulfonate, dialkyldimethylammonium salt, etc., and these may be appropriately selected depending on the ionic functional group introduced on the surface of the diamond fine particles. As an alkyl group used here, it is a C1-C6 integer, such as methyl, ethyl, propyl, butyl, pentyl, hexyl.

  In the case of diamond fine particles into which a hydrophilic polymer has been introduced, it is preferable to use a nonionic surfactant. For example, in the case of PEG, polyethylene glycol mono-4-octylphenyl ether and alkylphenol surfactants can be used.

  The surfactant used as the dispersant is preferably a homopolymer or copolymer surfactant having a molecular weight of 30,000 to 200,000. When the molecular weight is larger than 200,000, it causes cross-linking between diamond fine particles, and acts as an aggregating agent rather than a dispersing agent. On the other hand, if the molecular weight is smaller than 30,000, desorption from the diamond fine particles is likely to occur even if the adsorption rate is high, and the effect as a dispersing agent becomes small.

  In the case of producing a composite plating solution by adding the dispersion prepared as described above to the metal plating solution, the amount of diamond fine particles added may be 0.5 to 10 g / liter in the composition of the composite plating solution. preferable. If a plating treatment is performed using a composite plating solution in which the amount of added diamond fine particles is adjusted within this range, the diamond fine particles can be uniformly dispersed in the plating film, and the content of the diamond fine particles is 0.1 to 30 volumes. % Can also be adjusted.

  Examples of the reducing agent used in the composite plating solution include hypophosphites such as sodium hypophosphite, dimethylamine borane, and hydrazine, amine boranes, and hydrazine salts. The concentration of the reducing agent in the composite plating solution varies depending on the type of reducing agent used and the metal to be deposited, but is preferably 20 to 50 g / liter in the composition in the composite plating solution.

  In preparing the composite plating solution, it is preferable to add a complexing agent within a range that does not interfere with the dispersion state of the diamond fine particles. Examples of complexing agents that can be used in the composite plating solution include organic acids such as citric acid, lactic acid, succinic acid, malonic acid, propionic acid, adipic acid, malic acid, glycolic acid, and water-soluble salts thereof. Of these, one or a combination of two or more can be used. The concentration of the complexing agent to be added is preferably 10 to 40 g / liter in the composition in the composite plating solution.

  When a known electroless plating process is performed using the composite plating solution manufactured as described above, the substrate to be plated is immersed in the composite plating solution in which diamond fine particles are stably dispersed. Thus, a composite plating film in which diamond fine particles are uniformly dispersed in the nano order in the metal matrix can be formed on the surface of the object to be plated.

  Moreover, when implementing a plating process, in order to promote the reduction reaction of a metal ion and to keep the precipitation rate of a composite plating film constant, it is preferable that the acidity of a composite plating solution shall be pH 3-5. In order to adjust the pH of the composite plating solution, an acidic solution such as hydrochloric acid, sulfuric acid or sulfamic acid, or an alkaline solution such as sodium hydroxide or ammonium hydroxide can be appropriately added as a regulator.

  Furthermore, in order to maintain the deposition rate, it is preferable to adjust the bath temperature during the plating process to 85 to 90 ° C. In addition, if necessary, the plating efficiency can be improved by stirring the composite plating solution during the plating process or by shaking the object to be plated, and the appearance and thickness of the composite plating film can be kept constant. it can.

One preferred embodiment of the method for producing the composite plating solution described above and the composite plating method using the same is, for example, diamond fine particles (average grain size) in which a hydrophilic polymer or an ionic functional group as described above is introduced. Diameter; 1 nm to 1000 nm) and a Ni-P electroless composite plating solution (see the composition below) in which a surfactant is uniformly dispersed in the composite plating solution, and a composite plating method using the same.
<Composition of electroless composite plating solution>
-Nickel sulfate hexahydrate 25-30 g / liter-Surfactant 0.5-10 g / liter-Diamond fine particles 0.5-10 g / liter-Malic acid (complexing agent) 10-50 g / liter-Succinic acid ( Complexing agent) 10-50 g / liter. Sodium hypophosphite (reducing agent) 20-50 g / liter.

  In this composite plating method, the object to be plated is immersed in the above electroless composite plating bath adjusted to a liquid temperature of 85 to 90 ° C. and pH 4 to 5 for about 30 to 60 minutes to perform electroless composite plating. A composite plating film in which diamond fine particles are uniformly dispersed in the Ni-P matrix is formed on the surface of the substrate.

  According to this composite plating method, a composite plating film of 5 to 15 μm can be formed on the surface of the object to be plated, and diamond fine particles whose average particle diameter is adjusted to 1 nm to 1000 nm can be uniformly dispersed inside the film. It becomes. And the precipitation amount of a diamond fine particle can be 0.1-30 volume%, and it becomes possible to precipitate the quantity sufficient to exhibit the characteristic of a diamond fine particle.

  When performing the electroless composite plating process using the above electroless composite plating solution, the metal ions are reduced to the metal by the reducing agent by the progress of the plating process, and the diamond fine particles are co-deposited. The metal ion concentration, the reducing agent concentration and the diamond fine particle concentration in the liquid are lowered, and the pH is also lowered.

  Accordingly, it is preferable to replenish the metal plating solution, reducing agent, diamond fine particles and pH adjuster into the composite plating solution continuously or at regular intervals, and maintain their concentrations in the bathing condition. In this case, it is considered that the amount of decrease in the concentration of metal ions, the reducing agent and the fine diamond particles, the amount of change in pH, and the amount of precipitation of the composite plating film are proportional to each other. In addition, since the deposition rate of the composite plating film is considered to be substantially constant under the same plating conditions if the concentration of the composite plating solution is the same as the initial concentration, a certain amount of metal salt, reducing agent, By supplying appropriate amounts of the diamond fine particles and the pH adjusting agent, the concentration in the composite plating solution can be maintained at an almost initial concentration.

  By replenishing the metal salt consumed in the plating process, the electroless composite plating solution can continue the composite plating process satisfactorily for at least 2 turns, generally 3-4 turns. Even if the plating process is continuously performed, a composite plating film having a smooth surface and excellent uniformity can be stably formed, and the precipitation rate and the amount of eutectoid of the diamond fine particles are hardly decreased. Here, one turn represents the state of the composite plating solution when an amount of metal corresponding to the initial metal ion concentration in the electroless composite plating solution is deposited, and indicates the degree of wear of the composite plating solution.

  The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples.

Example 1
<Preparation of anionic functional group-introduced diamond fine particles>
SCM fine diamond (average particle diameter; 20 nm) manufactured by Sumiishi Materials Co., Ltd. was used as the diamond fine particles. In addition, as a macroazo initiator for introducing an anionic functional group on the surface of diamond fine particles, “V-501 (4,4′-azobis (4-cyanoantanoic acid))” (hereinafter “V”) manufactured by Wako Pure Chemical Industries, Ltd. -501 ").

  Diamond fine particles (1.0 g) and V-501 (1.0 g) were added to a 100 ml round bottom flask equipped with a stirrer, a cooling tube, and a thermocouple, and then 100 ml of methanol solvent was added and stirred. The reaction was carried out for 24 hours by heating to 50 ° C. in an atmosphere. After reacting for 24 hours, in order to increase the amount of anionic functional group introduced to the surface of the diamond fine particles, V-501 (1 g) was dissolved in 10 ml of methanol, added to the solution reacted for 24 hours, and then nitrogen. The reaction was carried out for 24 hours by heating to 50 ° C. in an atmosphere.

  After completion of the reaction, the reaction solvent was removed to remove unreacted monomers. In order to completely remove the monomer physically adsorbed on the surface of the diamond fine particles, 100 ml of methanol is added again, and the diamond fine particles are dispersed by ultrasonic treatment, and centrifuged at 1.5 × 104 rpm for about 60 minutes. went. After centrifugation, the diamond fine particles obtained by removing methanol were dried by suction drying.

  To the dried diamond fine particles (1.0 g), 100 ml of 0.1 M NaOH aqueous solution was added and dispersed by ultrasonic treatment, and the mixture was heated to 60 ° C. while being stirred with a magnetic stirrer and washed for 6 hours or more. . After washing, in order to separate the reaction product and the solvent, centrifugation was performed at 1.5 × 104 rpm for about 60 minutes. After centrifugation, the supernatant NaOH aqueous solution was removed, 30 ml of pure water was added, and neutralization treatment was performed to disperse the diamond fine particles by ultrasonic treatment. This neutralization treatment was repeated several times until the solution containing diamond fine particles became neutral.

  The anionic functional group-introduced diamond particles thus prepared were dispersed in 100 ml of pure water to obtain a 1% by weight diamond particle dispersion. The pH of the obtained dispersion was 6.8, the average particle size was about 12 nm, and the maximum particle size was about 30 nm. As a result of observing the dispersion with a microscope, aggregates of diamond fine particles were not observed.

FT-IR spectrum measurement was performed on the produced anionic functional group-introduced diamond fine particles. As a result of the measurement, new absorption not found in the raw diamond fine particles was observed in the vicinity of 1750 cm ⁻¹ , 1630 cm ⁻¹ and 1390 cm ⁻¹ , and the introduction of COOH groups to the surface of the diamond fine particles was confirmed.

  The produced anionic functional group-introduced diamond fine particles are dispersed in pure water at a concentration of 1 g / liter and sufficiently dispersed by ultrasonic treatment, and then a cationic surfactant (poly (diallyldimethylammonium chloride) 1 It was added to a concentration of 0.0 g / liter, and further sufficiently dispersed by ultrasonic treatment.

The resulting dispersion in which the diamond fine particles and the surfactant were uniformly dispersed was added to the metal plating solution to prepare a composite plating solution having the following composition.
<Composition of composite plating solution>
-Nickel sulfate hexahydrate 25 g / liter-Sodium hypophosphite monohydrate 30 g / liter-Malic acid 25 g / liter-Lactic acid 20 g / liter-Succinic acid 5 g / liter-Borax 5 g / liter-Diamond fine particle dispersion Liquid 2g / liter

  The prepared composite plating solution was adjusted to pH 5.0 by appropriately adding sulfuric acid or ammonium hydroxide solution. Next, the temperature of the composite plating solution was raised to 90 ° C. (use temperature of the composite plating solution). At this time, the fine diamond particles in the composite plating solution maintained a good dispersion state, and it was confirmed that the manufactured composite plating solution maintained a stable dispersion state even when the temperature was raised to the use temperature. . The dispersion state was confirmed to be a good dispersion state by visually checking the presence or absence of precipitation and the color of the composite plating solution.

  Such evaluation of the dispersion state can also be quantitatively evaluated by measuring the zeta potential and the particle size distribution. In addition, the stability of the dispersed state can be quantitatively evaluated by measuring the zeta potential and the particle size distribution in a state where the composite plating solution is heated to room temperature and then analyzing the change in the dispersed state. In that case, quantitative evaluation becomes possible by measuring the prepared composite plating solution with a zeta potential particle size distribution measuring device (for example, manufactured by Beckman Coulter, Inc .; product name Delsa Nano). 1 and 2 are graphs showing examples of measurement results of zeta potential and particle size distribution of the composite plating solution, respectively. No significant change is observed between the measurement results before the treatment (measured in a heated state) and after the treatment (measured in a cooled state at room temperature), indicating that a stable dispersion state is realized.

  A composite plating treatment was performed on a test piece (material; stainless steel (SUS304)) using the composite plating solution. The test pieces subjected to the composite plating treatment were evaluated for the appearance of the composite plating film and the amount of eutectoid of the diamond fine particles. The appearance of the test piece showed a uniform nickel gloss color, and the amount of eutectoid of diamond fine particles was about 10% by weight.

  FIG. 3 is an enlarged photograph of an SEM obtained by photographing a cross section of the formed composite plating film. As a result of observing the enlarged photograph shown in FIG. 3, it was confirmed that the diamond fine particles in the composite plating film were uniformly dispersed and eutectoid with an average particle size of about 20 nm.

(Example 2)
<Preparation of PEG-introduced diamond fine particles>
0.05 g of the same diamond fine particles as in Example 1 and 2.0 g of “VPE-0201” manufactured by Wako Pure Chemical Industries, Ltd. as a PEG macroazo initiator were added to the test tube. Further, 15 ml of o-dichlorobenzene was added as a reaction catalyst, and the reaction was carried out by heating to 70 ° C. in a nitrogen atmosphere while stirring with a magnetic stirrer.

  After the reaction, methanol was added to the test tube to stop the reaction, and the product was washed using methanol as a washing solvent. In order to remove the non-grafted PEG, the product is dispersed in methanol, subjected to ultrasonic washing for about 5 minutes, and then centrifuged at 1.5 × 104 rpm for about 30 minutes to dissolve the non-grafted PEG. The supernatant was removed. This operation was repeated 3 times to remove non-grafted PEG. Thereafter, the precipitate was sufficiently dried by heating to 50 ° C. under reduced pressure.

FI-IR spectrum measurement was performed on the product. As a result, 1110 cm ^-1, absorption showing the characteristics of the ether bond derived from PEG chains was observed around 1700 cm ^-1 and 2950 cm ^-1, confirming that the surface of the diamond particles PEG chains introduced by graft polymerization It was. Absorption derived from ester bonds was also observed. From these measurement results, the condensation reaction between the COOH group introduced on the surface of the diamond fine particle and the hydroxyl group at the end of PEG proceeds, and PEG is introduced by graft polymerization onto the surface of the diamond fine particle via an ester bond. It suggests that.

  The produced PEG-introduced diamond fine particles are dispersed at a concentration of 1 g / liter in pure water and sufficiently dispersed by ultrasonic treatment, and then a nonionic surfactant (polyethylene glycol mono-4-octylphenyl ether) is added to 1 It was added to a concentration of 0.0 g / liter, and further sufficiently dispersed by ultrasonic treatment.

The resulting dispersion in which the diamond fine particles and the surfactant were uniformly dispersed was added to the metal plating solution to prepare a composite plating solution having the following composition.
<Composition of composite plating solution>
-Nickel sulfate hexahydrate 25 g / liter-Sodium hypophosphite monohydrate 30 g / liter-Malic acid 25 g / liter-Lactic acid 20 g / liter-Succinic acid 5 g / liter-Borax 5 g / liter-Diamond fine particle dispersion Liquid 0.1g / liter

  The prepared composite plating solution was adjusted to pH 5.0 by appropriately adding sulfuric acid or ammonium hydroxide solution. Next, the temperature of the composite plating solution was raised to 90 ° C. (use temperature of the composite plating solution). At this time, the fine diamond particles in the composite plating solution maintained a good dispersion state, and it was confirmed that the manufactured composite plating solution maintained a stable dispersion state even when the temperature was raised to the use temperature. . The dispersion state was confirmed by visual observation as in Example 1.

  A composite plating treatment was performed on a test piece (material; stainless steel (SUS304)) using the composite plating solution. The test pieces subjected to the composite plating treatment were evaluated for the appearance of the composite plating film and the amount of eutectoid of the diamond fine particles. The appearance of the test piece showed a uniform nickel luster color, and the amount of eutectoid of the diamond fine particles was about 1% by weight.

  FIG. 4 is an enlarged photograph of an SEM obtained by photographing a cross section of the formed composite plating film. As a result of observing the enlarged photograph shown in FIG. 4, it was confirmed that the diamond fine particles in the composite plating film were uniformly dispersed and eutectoid with an average particle diameter of about 100 nm.

Claims (9)

  A composite in which diamond fine particles with a hydrophilic polymer or ionic functional group introduced are dispersed together with an ionic or nonionic surfactant and added to the metal plating solution to stably disperse the diamond fine particles. A method for producing a composite plating solution, comprising producing a plating solution.   The manufacturing method according to claim 1, wherein an average particle diameter of the diamond fine particles is 1 nm to 1000 nm.   The method according to claim 1 or 2, wherein the surfactant is a homopolymer or copolymer surfactant having a molecular weight of 30,000 to 200,000.   The metal plating solution contains one or more metal ions selected from the group consisting of nickel ions, cobalt ions, copper ions, gold ions, iron ions, palladium ions, platinum ions, tin ions and rhodium ions. The manufacturing method according to any one of claims 1 to 3.   In the metal plating solution, diamond fine particles having an average particle diameter of 1 nm to 1000 nm and a ionic or nonionic surfactant having a hydrophilic polymer or ionic functional group introduced therein are uniformly dispersed. Composite plating solution.   6. The composite plating solution according to claim 5, wherein the concentration of the diamond fine particles is 0.1 g / liter to 20 g / liter.   The composite plating solution according to claim 5 or 6, wherein the surfactant is a homopolymer or copolymer surfactant having a molecular weight of 30,000 to 200,000.   A composite plating film in which the diamond fine particles are uniformly dispersed in a metal matrix is formed by performing a plating treatment on a substrate surface using the composite plating solution according to claim 5. A composite plating method.   A composite plating film formed by the composite plating method according to claim 8.