JP7624306B2 - Eutectoid plating solution - Google Patents

Description

The present invention relates to a eutectoid plating solution.

In the manufacture of products in various fields, plating techniques such as electrolytic plating and electroless plating are widely used as techniques for forming films on the surfaces of components. Examples of conventional plating techniques are disclosed in Patent Documents 1 and 2.

In recent years, eutectoid plating has become known, in which a plating reaction is carried out in a plating solution containing wear-resistant particles such as silicon carbide particles. In this type of eutectoid plating, it is possible to impart new functions such as wear resistance, lubricity, and corrosion resistance to the plated film depending on the properties of the particles contained, so it is often used for substrates that require wear resistance and hardness, such as engine parts for automobiles and aircraft, and connectors that slide frequently, and various means for such eutectoid plating have been proposed.

Patent Documents 3 and 4 disclose eutectoid plating solutions that contain at least water, a Group 4 element-based coupling agent having an amino group, silicon carbide particles or silicon oxide particles, and a metal source.

JP 2003-027202 A Special Publication No. 2008-516039 JP 2020-180326 A JP 2020-117797 A

If sufficient dispersibility of silicon carbide particles or silicon oxide particles is not obtained, the silicon carbide particles may be unevenly distributed in the obtained plating layer, or the plating layer may not be formed well. According to the means disclosed in Patent Documents 3 and 4, sufficient dispersibility of silicon carbide particles or silicon oxide particles is obtained.

On the other hand, depending on the desired plating properties, it may be desirable to use a plating solution with a high pH. When such a plating solution is used, even the measures described in Patent Documents 3 and 4 may still leave room for improvement in eutectoid properties.

Therefore, there is a need to provide a new eutectoid plating solution that can produce a plating layer with good eutectoid properties even when a plating solution with a high pH is used.

As a result of intensive research, the present inventors have found that the above problems can be solved by the following means, and have completed the present invention. That is, the present invention is as follows:
<Aspect 1> A method for preparing a catalyst for preparing a catalyst containing at least water, a Group 4 element-based coupling agent having a lactate group or a salt thereof, silicon-based particles, and a metal source, and having a pH of 5.5 to 8.0;
Eutectoid plating solution.
<Aspect 2> The eutectoid plating solution according to aspect 1, wherein the Group 4 element-based coupling agent is a titanium coupling agent or a zirconium coupling agent.
<Aspect 3> The eutectoid plating solution according to aspect 1 or 2, wherein the Group 4 element-based coupling agent has a hydroxyl group and a lactate group or a salt thereof.
<Embodiment 4> An aqueous dispersion containing at least water, a Group 4 element-based coupling agent having a lactate group or a salt thereof, and silicon-based particles.

The present invention provides a novel eutectoid plating solution that can produce a plating layer with good eutectoid properties even when a plating solution with a high pH is used.

<Eutectoid plating solution>
The eutectoid plating solution of the present invention is
The composition contains at least water, a Group 4 element-based coupling agent having a lactate group or a salt thereof, at least one of silicon-based particles, and a metal source, and has a pH of 5.5 to 8.0.
It is a eutectoid plating solution.

The eutectoid plating solution of the present invention may be an electrolytic plating solution or an electroless plating solution.

The content of silicon-based particles in the eutectoid plating solution may be 0.001% by mass or more, 0.003% by mass or more, 0.005% by mass or more, 0.01% by mass or more, 0.03% by mass or more, 0.05% by mass or more, or 0.07% by mass or more, based on the total mass of the eutectoid plating solution, and may be 5% by mass or less, 3% by mass or less, 1% by mass or less, 0.5% by mass or less, 0.3% by mass or less, or 0.2% by mass or less.

The content of the Group 4 element-based coupling agent in the eutectoid plating solution may be 0.001% by mass or more, 0.003% by mass or more, 0.005% by mass or more, 0.01% by mass or more, 0.03% by mass or more, 0.05% by mass or more, or 0.07% by mass or more, based on the total mass of the eutectoid plating solution, and may be 5% by mass or less, 3% by mass or less, 1% by mass or less, 0.5% by mass or less, 0.3% by mass or less, or 0.2% by mass or less.

The ratio of the mass of the Group 4 element-based coupling agent in the eutectoid plating solution to the total mass of the silicon-based particles may be 1% or more, 3% or more, 5% or more, 10% or more, 20% or more, 30% or more, 50% or more, 70% or more, 100% or more, 130% or more, 150% or more, 200% or more, 250% or more, or 280% or more, and may be 1000% or less, 900% or less, 800% or less, 700% or less, 600% or less, 500% or less, 400% or less, 350% or less, or 330% or less.

The eutectoid plating solution may also contain other particles.

The pH of the eutectoid plating solution may be 5.5 or more, 5.7 or more, 5.9 or more, or 6.0 or more, and may be 8.0 or less, 7.5 or less, 7.0 or less, 6.8 or less, 6.6 or less, 6.4 or less, or 6.2 or less.

Each component of the present invention is described below.

<water>
The water may be ion-exchanged water, distilled water, or the like.

<Group 4 Element Coupling Agent>
The Group 4 element coupling agent is a Group 4 element coupling agent having a lactate group or a salt thereof. Here, in the present invention, the "Group 4 element coupling agent" refers to a compound having a hydroxyl group or a hydrolyzable group and a hydrophilic organic functional group bonded to a Group 4 atom, whereby the hydroxyl group that is originally present or obtained by hydrolysis of the hydrolyzable group chemically bonds with an inorganic material, and the hydrophilic organic functional group provides hydrophilicity.

The Group 4 elements are titanium, zirconium, hafnium, and rutherfordium. From the viewpoint of dispersibility, it is preferable to use titanium or zirconium as the Group 4 element, and especially titanium.

The hydrolyzable group may be, for example, an alkoxy group, for example, a linear or branched alkoxy group having 1 to 10 carbon atoms, such as an n-methoxy group, an n-ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, a tert-butoxy group, an n-pentoxy group, an isopentoxy group, a neopentoxy group, a tert-pentoxy group, a hexoxy group, an isohexoxy group, and the like.

A lactate group has the structure: [-OCH(CH ₃ )COOH]. A salt of a lactate group may be, for example, an ammonium lactate group: [-OCH(CH ₃ )COO(NH ₄ )].

The inventors have discovered that the Group 4 element-based coupling agent described above adsorbs to the surfaces of silicon-based particles and acts as a dispersant, allowing these particles to disperse in the plating solution, forming a plating layer in which the silicon-based particles are well dispersed.

By dispersing the above-mentioned Group 4 element-based coupling agent in the plating solution, silicon-based particles of any average particle size, particularly silicon-based particles with an average particle size of 150 nm or less, can be dispersed well, and as a result, when the plating layer is formed, a sufficient amount of silicon-based particles can be evenly distributed in the plating layer.

The Group 4 element coupling agent may have a hydroxyl group and a lactate group or a salt thereof as a hydrophilic organic functional group in the Group 4 element. In this case, the Group 4 element coupling agent may have one hydroxyl group and three lactate groups or a salt thereof, two hydroxyl groups and two lactate groups or a salt thereof, or three hydroxyl groups and one lactate group or a salt thereof, but having two or more hydroxyl groups is preferable from the viewpoint of improving the dispersibility of the silicon-based particles.

As a Group 4 element-based coupling agent having a hydroxyl group and a lactate group or a salt thereof, commercially available ones can be used, such as Orgatix TC-300, TC-310, ZC-300, etc., available from Matsumoto Fine Chemical Co., Ltd.

<Silicon-based particles>
Silicon-based particles are generally particles composed of silicon compounds, and may be, for example, silicon carbide particles or silicon oxide particles.

The average particle size of the silicon-based particles may be 10 nm or more, 20 nm or more, 30 nm or more, 40 nm or more, 50 nm or more, 60 nm or more, 70 nm or more, 80 nm or more, 90 nm or more, or 100 nm or more, and may be 100 μm or less, 50 μm or less, 30 μm or less, 20 μm or less, 10 μm or less, 7 μm or less, 5 μm or less, 3 μm or less, 1 μm or less, 700 nm or less, 500 nm or less, 400 nm or less, 370 nm or less, 350 nm or less, 330 nm or less, 300 nm or less, 270 nm or less, 250 nm or less, 230 nm or less, 200 nm or less, or 150 nm or less. The average particle size here is appropriately selected depending on the size of the silicon oxide particles to be treated. For particles less than 1 μm, it is the histogram average particle size (D50) based on the scattering intensity distribution measured by dynamic light scattering, and for particles of 1 μm or more, it is the D50 value calculated on a volume basis by laser diffraction. In particular, when the average particle size is 150 nm or less, the eutectoid property is improved, and as a result, the wear resistance of the plating layer obtained using the eutectoid plating solution of the present invention is improved.

(Silicon carbide particles)
The silicon carbide particles may be commercially available silicon carbide particles.

(Silicon oxide particles)
The silicon oxide particles may be commercially available silicon oxide particles. Here, in the present invention, "silicon oxide particles" means particles containing silicon oxide on at least a part of the surface. Examples of such silicon oxide particles include pure silicon oxide particles, particles having silicon oxide on the whole or part of the surface, etc.

Silicon oxide particles having silicon oxide present on the entire or partial surface can be obtained, for example, by oxidizing silicon carbide particles. The silicon oxide content in such silicon oxide particles may be 0.01% by mass or more, 0.1% by mass or more, 1% by mass or more, 3% by mass or more, 5% by mass or more, 7% by mass or more, 10% by mass or more, 15% by mass or more, 20% by mass or more, 25% by mass or more, or 30% by mass or more, or 99% by mass or less, 95% by mass or less, 90% by mass or less, 80% by mass or less, 70% by mass or less, 60% by mass or less, 50% by mass or less, 45% by mass or less, 40% by mass or less, or 35% by mass or less. This content can be measured, for example, by measuring the change in mass before and after the oxidation of silicon carbide.

Metal Source
The metal source may be in various forms depending on the metal to be plated, the mode of plating, etc. The metal source is not particularly limited, but may be, for example, a metal salt of the metal to be plated, such as an inorganic acid salt such as sulfate, hydrochloride, pyrophosphate, or sulfamic acid, or an organic acid salt such as cyanide.

Metals to be plated may be, for example, copper, nickel, chromium, zinc, tin, silver, gold, etc.

Other Ingredients
As other components, for example, a pH adjuster, a pH buffer, a gloss agent, etc. may be used.

In addition, particularly in the case of electrolytic plating solutions, the eutectoid plating solution may contain an electrolyte.

In particular, in the case of electroless plating solutions, the eutectoid plating solution may contain a reducing agent. Examples of the reducing agent that can be used include inorganic acid salts such as sulfates, hydrochlorides, pyrophosphates, phosphinates, sulfamates, and tetrahydroborates of alkali metals or alkaline earth metals, and organic acid salts such as cyanides. Examples of the reducing agent that can be used include dimethylamine borane, hydrazine, and titanium trichloride.

In particular, in the case of electroless plating solutions, the eutectoid plating solution may contain a complexing agent. Examples of the complexing agent that can be used include carboxylic acids such as acetic acid, lactic acid, oxalic acid, malonic acid, malic acid, and tartaric acid, and amino acids such as glycine, alanine, and asparagine.

<Aqueous dispersion>
The aqueous dispersion contains at least water, a Group 4 element-based coupling agent having a lactate group or a salt thereof, and silicon-based particles. This aqueous dispersion may be an aqueous dispersion for preparing a eutectoid plating solution.

The aqueous dispersion can be produced, for example, by mixing and stirring water, a Group 4 element-based coupling agent having a lactate group or a salt thereof, and silicon-based particles, and then dispersing the mixture using a bead mill or the like.

The content of silicon-based particles in the aqueous dispersion may be 0.1% by mass or more, 0.3% by mass or more, 0.5% by mass or more, 1% by mass or more, 2% by mass or more, 3% by mass or more, 5% by mass or more, or 7% by mass or more, based on the total mass of the aqueous dispersion, and may be 50% by mass or less, 40% by mass or less, 30% by mass or less, 25% by mass or less, 20% by mass or less, 15% by mass or less, or 13% by mass or less.

The content of the Group 4 element-based coupling agent in the aqueous dispersion may be 0.1% by mass or more, 0.3% by mass or more, 0.5% by mass or more, 0.7% by mass or more, 1% by mass or more, 2% by mass or more, 3% by mass or more, 5% by mass or more, or 7% by mass or more, based on the total mass of the aqueous dispersion, and may be 50% by mass or less, 40% by mass or less, 30% by mass or less, 25% by mass or less, 20% by mass or less, 15% by mass or less, or 13% by mass or less.

Other particles
Examples of other particles that can be used include _Al2O3 , _Cr2O3 , _{Fe2O3 , TiO2 , ZrO2} , _ThO2 , _CeO2 , _BeO2 , MgO, _CdO , diamond, SiC, TiC, _WC , VC, ZrC, TaC, _Cr3C2 , _B4C , BN, _ZrB2 , _TiN , Si3N4, _WSi2 , MoS, _WS2 , _CaF2 , _BaSO4 , _SrSO4 , ZnS, CdS, _TiH2 , _NbC , _Cr3B2 , _UO2 , _CeO2 , graphite fluoride, graphite, glass, kaolin, corundum, pigments _, etc. Also usable are PTFE, polystyrene, polypropylene, polycarbonate, polyamide, polyacrylonitrile, polypyrrole, polyaniline, acetyl cellulose, polyvinyl acetate, polyvinyl butyral, or copolymers (polymers of methyl methacrylate and methacrylic acid). These other particles can be used alone or in combination.

<Production method of eutectoid plating solution>
The eutectoid plating solution can be produced by a method including mixing the above-mentioned aqueous dispersion with a metal plating solution. In this case, the content of the aqueous dispersion may be 0.1 mass% or more, 0.3 mass% or more, 0.5 mass% or more, or 0.7 mass% or more based on the mass of the entire eutectoid plating solution, and may be 10 mass% or less, 7 mass% or less, 5 mass% or less, 3 mass% or less, or 2 mass% or less.

<Metal plating solution>
The metal plating solution contains at least a metal source. The metal plating solution may also contain other components as listed for the eutectoid plating solution. As such a metal plating solution, a commercially available metal plating solution may be used by diluting it, for example with a predetermined amount of distilled water, according to the instructions of the supplier, depending on the intended use of plating. In the following, the term "metal plating solution" refers to the metal plating solution immediately before being mixed with the above-mentioned aqueous dispersion, i.e., the diluted metal plating solution, if any, is used.

The pH of the metal plating solution may be 5.5 or more, 5.7 or more, 5.9 or more, or 6.0 or more, and may be 8.0 or less, 7.5 or less, 7.0 or less, 6.8 or less, 6.6 or less, 6.4 or less, or 6.2 or less.

When the metal plating solution contains phosphorus in an amount such that the phosphorus content of the resulting plating layer is 7% by mass or less, 6% by mass or less, 5% by mass or less, 4% by mass or less, or 3% by mass or less, the pH of the metal plating solution tends to be in the above range, and the configuration of the present invention is beneficial. In addition, this content can increase the hardness and wear resistance of the resulting plating layer. This content may be more than 0% by mass, 0.1% by mass or more, 0.5% by mass or more, 1% by mass or more, or 2% by mass or more.

The present invention will be specifically explained using examples and comparative examples, but the present invention is not limited to these.

<Preparation of eutectoid plating solution>
Example 1
10 parts by mass of silicon oxide particles having an average particle size of 100 nm obtained by oxidizing silicon carbide particles, 1.0 part by mass of titanium lactate ammonium salt (Orgatix TC-300, Matsumoto Fine Chemical Co., Ltd., active ingredient 44%) referred to in Table 1 as lactate group-containing titanium coupling agent (TiCP)-A, and 89.0 parts by mass of ion-exchanged water were stirred and mixed to a uniform state, and then this was dispersed using a paint shaker (zirconia beads having a diameter of 0.3 mm) for a dispersion time of 2 hours to prepare the aqueous dispersion of Example 1. The silicon oxide content in the silicon oxide particles obtained by oxidizing silicon carbide particles was 40% by mass.

Examples 2 to 11, Comparative Examples 1 to 7, and Reference Examples
Using the constitution shown in Table 1, aqueous dispersions of Examples 2 to 11, Comparative Examples 1 to 7 and Reference Example were prepared in the same manner as in Example 1.

The details of the other dispersants mentioned in Table 1 are as follows:
Lactate group-containing TiCP-B: Titanium lactate (Orgatix TC-310, Matsumoto Fine Chemical Co., Ltd., active ingredient 41%)
Lactate group-containing zirconium coupling agent (ZrCP): zirconium lactate ammonium (Orgatics ZC-300, Matsumoto Fine Chemical Co., Ltd., active ingredient 12%)
Silicone-based surfactant: Water-based silicone-based surfactant (BYK-349, BYK, 100% active ingredient)
Anionic surfactant: Wetting and dispersing agent for aqueous systems (DISPERBYK-2015, BYK, non-volatile content 40%)
Amino group-containing TiCP: Titanium diethanol aminate (Orgatix TC-500, Matsumoto Fine Chemical Co., Ltd., active ingredient 70%)

Furthermore, with regard to the morphology of the silicon-based particles listed in Table 1, silicon oxide particles obtained by oxidizing silicon carbide particles are referred to as "surface oxidized," pure silicon oxide particles are referred to as "oxidized," and silicon carbide particles are referred to as "carbonized."

<<Measurement of the average particle size of silicon-based particles in an aqueous dispersion>>
The average particle size of the silicon-based particles in each of the resulting aqueous dispersions was measured by dynamic light scattering.

<<Preparation of plating solution and plating layer>>
One part by mass of each of the prepared dispersions was mixed with 99 parts by mass of a plating solution to prepare a eutectoid plating solution. The pH of each of the prepared plating solutions was then measured.

Here, in Table 1, what is referred to as "high pH plating solution" refers to Enplate NI-426 (Meltex, phosphorus content of the resulting plating layer is 1-3% by mass) diluted with a specified amount of distilled water, and what is referred to as "low pH plating solution" refers to SC-93-0 (Nippon Kanigen, phosphorus content of the resulting plating layer is 9-10% by mass) diluted with a specified amount of distilled water. The pH of the high pH plating solution and the low pH plating solution were 6.2 and 4.5, respectively.

Using each of the prepared eutectoid plating solutions, an iron substrate was coated with a plating layer having a thickness of 500 μm by electroless plating.

Evaluation of the eutectoid state
The cross section of the coated plating layer was observed by an electron microscope to evaluate the eutectoid state. The evaluation criteria were as follows:
A: A sufficient amount of silicon-based particles are evenly present.
B: A sufficient amount of silicon-based particles is present, but they are somewhat unevenly distributed.
C: Silicon-based particles are not observed, or are present but are unevenly distributed or the amount thereof is insufficient.

The configurations and evaluation results of the examples and comparative examples are shown in Table 1. In Table 1, the ratio of the mass of the Group 4 element-based coupling agent to the mass of the silicon-based particles in the eutectoid plating solution is referred to as "D/P."

From Table 1, it can be seen that when a plating solution with a high pH is used, in the aqueous dispersions of Examples 1 to 11 using a Group 4 element-based coupling agent containing a lactate group or its salt, the silicon-based particles are well dispersed in the aqueous dispersion, whether the silicon-based particles have an average particle size of 100 μm or 1000 μm, and when this aqueous dispersion is mixed with a commercially available plating solution to form a eutectoid plating solution, it shows good eutectoid properties.

In contrast, in the aqueous dispersions of Comparative Examples 1 to 6, which used a silicon-based surfactant, an anionic surfactant, and a Group 4 element-based coupling agent that did not contain a lactate group or a salt thereof, the silicon-based particles were not well dispersed in the aqueous dispersion, regardless of whether the silicon-based particles had an average particle size of 100 nm or 1000 nm, and when this aqueous dispersion was mixed with a low-phosphorus plating solution to form a eutectoid plating solution, the eutectoid property was not good.

In addition, looking at the results of Comparative Example 7 and Reference Example, when a plating solution with a low pH was used, the eutectoid property was not good when a titanium coupling agent containing a lactate group or its salt was used, whereas the eutectoid property was good when a titanium coupling agent containing an amino group was used.

Claims (4)

The composition contains at least water, a Group 4 element-based coupling agent having a lactate group or a salt thereof, silicon carbide particles and/or silicon oxide particles , and a metal source, and has a pH of 5.5 to 8.0 .
Eutectoid plating solution. The eutectoid plating solution according to claim 1, wherein the Group 4 element coupling agent is a titanium coupling agent or a zirconium coupling agent. The eutectoid plating solution according to claim 1 or 2, wherein the Group 4 element-based coupling agent has a hydroxyl group and a lactate group or a salt thereof. an aqueous dispersion containing at least water, a Group 4 element-based coupling agent having a lactate group or a salt thereof, and silicon carbide particles and/or silicon oxide particles;
A eutectoid plating solution containing at least a metal source;
The method for producing the eutectoid plating solution according to claim 1, comprising mixing the above.