JPS6137357B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a highly corrosion-resistant band plated with noble metal, which has excellent corrosion resistance and adhesion, and greatly expands the degree of freedom in design.

Conventional precious metal plating bands are made of nickel silver, monel,
Some were manufactured from copper alloy materials such as brass and then wet-plated, or in rare cases, they were manufactured from stainless steel and then wet-plated. In addition, there is also a gold band called gold bari, which is made of gold and stainless steel clad material (base material is SUS385, etc.), and only the minimum necessary part of the exterior is decorated with gold. There are also solid pieces made of precious metals.

Wet-plated products on copper-based alloys such as nickel silver, Monel, and brass are easy to manufacture and wet-plated.
Although it is still the mainstream of plating bands today, it is unavoidable that the surface plating layer peels off, wears, and scrapes during carrying, resulting in corrosion elution and discoloration of exposed parts of the base material, and the surface layer between component parts falls off due to friction. This always occurs when using a mobile phone. Furthermore, it is known that the plating coverage of the joints and contact areas between the band components is poor, and that corrosion and elution of the base material easily occurs in these areas in corrosive environments such as sweat and seawater. Furthermore, as shown above, these joints and contact areas are the parts that experience the most friction while being carried, and the plating liquid and plating pretreatment liquid remain in these parts even after plating, promoting corrosion. , and corrosive liquids such as sweat and seawater while carrying the device remain in this area most of the time, which is a major problem. Furthermore, the higher-quality products have a more dense assembly structure, which has a greater possibility of amplifying the above problems, and the recent market has been trending toward luxury, and the future shape of metsuki bands is beginning to be questioned. .

In order to solve these problems, we believe that even after the surface layer falls off, corrosion and dissolution of the base material can be avoided.
Some attempts have been made to use stainless steel, which has a proven track record of corrosion resistance, as the substrate, but the pretreatment for plating stainless steel with precious metals damages the corrosion-resistant oxide layer on the surface layer, which is characteristic of stainless steel. In addition, the adhesion of wet plating to stainless steel is not sufficient, and the gaps formed on the surface of the mesh band left in the plating pre-treatment are left with an unfinished corrosion-resistant oxide film, and the plating process is difficult. Coupled with the fact that the precious metal is exposed to the corrosive environment of the market without being completely coated, and that this gap has the same drawbacks as the precious metal plated band on the copper-based alloy mentioned above, the above-mentioned copper alloy products and The quality situation in the market is not good because it shows the same or inferior corrosion resistance.

The object of the present invention is to eliminate all of these essential drawbacks of precious metal plated bands and to provide a product of truly excellent quality.

In order to achieve the above object, the gist of the present invention is that the weight ratio is 9 to 18% Cr, 0.03% or less C, 4
A mesh band for a watch is made of an alloy consisting of % or less Ag, the balance Ni and unavoidable impurities, and has gaps formed on its surface. First, the entire band is coated with a resist, and then the band surface is coated with a resist. Then, the resist is removed only from the band surface so that the resist remains in the gap, and then wet base plating and precious metal plating are applied to the band surface. A method for manufacturing a corrosion-resistant metal band for a wristwatch, which is characterized by removing residual resist and then heat-treating the entire band at 200 to 900°C,
By making improvements to the base material, surface treatment method, etc., we have created a precious metal layer that significantly improves adhesion strength by heat diffusion only on the necessary parts of the band surface appearance, without damaging the inherent high corrosion resistance of the base material during the intermediate process. This is what we do.

First, the material used is an alloy consisting of 9 to 18% Cr, 4% or less Ag, and the balance Ni, with a carbon content of 0.03% or less so as not to reduce corrosion resistance during the heat treatment process for noble metal diffusion. A photoresist solution is infiltrated and coated over the entire band made of this material. After that, only the necessary areas are exposed, and after resist etching, precious metal plating is applied to only those areas using a wet method after the necessary under-plating. If you want to plate the entire band with precious metal, you can select a specific angle to expose and etch the entire band after resist coating, and the resist will remain only in the above-mentioned gap, and this area will be covered with pre-treatment liquid. It will not be damaged or coated with precious metal plating with unstable adhesion. From the outside, it looks as if the whole thing is coated with precious metal. Also, in the case of partial exposure, the protection of the gap is the same. After precious metal plating, the above-mentioned remaining resist is peeled off, and a surface layer diffusion treatment is performed at 200 to 900°C. At temperatures below 200℃, the diffusion time becomes longer and unsatisfactory adhesion is obtained;
In the above cases, the material softens and it becomes difficult to maintain the strength as a band.

If Cr is less than 9%, corrosion resistance will be poor, and 18%
If it is more than that, the workability will deteriorate and it will be difficult to finish it into a band. The amount of Ag improves processability, but 4
If it exceeds %, the corrosion resistance will decrease. Carbon improves forgeability, but if it exceeds 0.03%, it becomes a compound with Cr in the diffusion process in the post-process, reducing the corrosion resistance of the base material. Precious metal plated low carbon Cr-Ni steel bands manufactured using this process have corrosion resistance in the gap areas that is better than ordinary stainless steel bands, and the precious metal coating is more durable than conventional wet plated steel alloys. It exhibits superior adhesion, equivalent to or better than precious metal flat products, and exhibits extremely excellent properties in both corrosion resistance and adhesion, and can be strongly coated with precious metals on any model in terms of design and structure. can. The present invention will be explained below with reference to Examples.

Example 1 Weight ratio: 12.4% Cr, 0.02% C, 1.3% Ag,
A mesh band is manufactured from an alloy with the remainder being Ni, and after final surface finishing, it is coated with a photoresist solution in an ultrasonic container, and the entire front and back surfaces are exposed to light at a 60° angle to the surface. After resist etching, 0.5μ Ni plating was performed as an under plating, and then 5μ 22K gold plating was applied. Next, after peeling off the resist remaining in the gaps on the band surface, surface diffusion treatment was performed at 400°C for 1 hour in an ammonia decomposition gas atmosphere. When we conducted an actual mobile phone test on the 2,000 bands obtained in this way using a monitor, we found that out of 2,000 bands, the conventional 22K gold-plated product on nickel silver was removed over two years.
While 1,324 products were defective, only 3 products were found to be defective.
Only 18 defective products were produced during the year.

Example 2 Weight ratio: 10.8% Cr, 0.015% C, 0.5% Ag, balance
A band was manufactured from an alloy made of Ni using the same process as in Example 1, and after the same bottom plating as in Example 1 was applied, a 4.3 μm layer of 63% palladium nickel was applied, and then rhodium plating was applied as a final plating.
0.7μ was applied, the resist remaining in the gaps on the band surface was removed, and a surface diffusion heat treatment was performed at 450°C for 1 hour in a hydrogen gas atmosphere to produce a finished product. When we conducted a monitor test similar to Example 1, we found that 21
There were only defective books.

Claims (1)

[Claims] 1 9 to 18% Cr by weight, 0.03% or less C, 4
A mesh band for a watch is made of an alloy consisting of % or less Ag, the balance Ni and unavoidable impurities, and has gaps formed on its surface. First, the entire band is coated with a resist, and then the band surface is coated with a resist. Then, the resist is removed only from the band surface so that the resist remains in the gap, and then wet base plating and precious metal plating are applied to the band surface. A method for manufacturing a corrosion-resistant metal band for a wristwatch, which comprises removing residual resist and then heat-treating the entire band at 200 to 900°C.