【発明の詳細な説明】[Detailed description of the invention]
本発明は金または金合金の電解エツチング浴に
関するもので、特に金電鋳品や圧延あがりの金製
品などの金装飾品の電解エツチング浴に関するも
のである。
従来、電解エツチング浴としては主にシアンや
クロム酸等の有害物を使用したものが多く用いら
れていた。そして、これらの有害物を使用しない
浴として硫酸−リン酸−塩化ナトリウム浴−塩酸
浴が知られている。しかし、この浴では焼鈍すれ
ば光沢面がでるものの、加工品は光沢がなく、ま
た形状が複雑になるとくぼんだ部分は光沢が得ら
れず、雲つてくるという欠点があつた。さらに、
硫酸，リン酸，塩化ナトリウム，塩酸という四成
分の系を用いているため浴が複雑でその維持管理
が困難であるという欠点を有していた。
本発明は上記欠点に鑑みなされたもので、シア
ンやクロム酸等の有害物を使用せず、しかも焼鈍
品，加工品，電鋳品の区別なく光沢面がえられる
電解エツチング浴を提供するものである。
本発明における電解エツチング浴は、酢酸と塩
酸と水からなる浴で、それぞれの割合が容量比で
(a) 水：（塩酸＋酢酸）＝１：0.1〜100の関係があ
り、かつ
(b) 塩酸：酢酸＝１：１〜10の関係があることを
特徴とするものである。
本発明において、最も大きな特徴は酢酸であ
る。つまり、塩酸と水の浴では光沢が全く得られ
なかつたものが、系の酢酸濃度を増すに従つて、
浴抵抗が増大するとともに光沢が良くなる。しか
し、系の酢酸濃度が濃くなりすぎると、凹凸が大
きい形状の品物では凹部の抵電流密度部の雲り度
合が激しくなり実用的でない。ここで、塩酸：酢
酸の比率を１：１〜10及び水：（塩酸＋酢酸）の
比率を１：0.1〜100に限定した理由は、上で述べ
たように酢酸の量が塩酸：酢酸＝１：１より少な
くなると光沢が全く得られなくなり、酢酸の量が
塩酸：酢酸＝１：10より多くなると凹凸が大きい
形状の品物では凹部の雲り度合が激しくなるため
である。また水の量が水：（塩酸＋酢酸）＝１：
100より少なくなると、エツチング速度が速すぎ
て表面が荒れてしまい、逆に水の量が水：（塩酸
＋酢酸）＝１：0.1より多くなるとエツチング速度
が遅くなりすぎて効率が悪くなるためである。
以下、実施例と従来例について説明する。
〔実施例 １〕
幅10mm×長さ50mm×厚さ0.5mmの金板を圧延あ
がりの加工品（No.１）と600℃30分間熱処理した
焼鈍品（No.２）及び幅10mm×長さ50mm×厚さ50μ
の電鋳品（No.３）を作成した。これを、酢酸400
ml，水12ml，塩酸80mlの組成の浴に室温で30v2
分間電解エツチングした。その結果No.１〜No.３と
も全て光沢があつた。特にNo.１とNo.２の光沢は著
しかつた（鏡面光沢）。
〔従来例 １〕
実施例１と同様の加工品（No.４）、焼鈍品（No.
５）、電鋳品（No.６）を作成し、これを塩化ナト
リウム200ｇ／，硫酸100ml／，リン酸100
ml／，塩酸50ml／の浴に室温で500A／ｄm2
20秒間電解エツチングした。その結果No.４とNo.６
は光沢があつたが、No.５の焼鈍品は光沢がなかつ
た。また、No.４の加工品はNo.１に比べ光沢が劣つ
ていた。
〔実施例 ２〕
幅10mm×長さ50mm×厚さ５mmの焼鈍品（No.７〜
No.10）を５mmφの円筒状にし、実施例１と同様な
浴で下表左欄の条件で電解エツチングし、光沢度
合，曇り状態エツチング量を調べたところ下表右
欄の結果を得た。
The present invention relates to an electrolytic etching bath for gold or gold alloys, and more particularly to an electrolytic etching bath for gold ornaments such as electroformed gold products and rolled gold products. Conventionally, many electrolytic etching baths have been used that mainly contain harmful substances such as cyanide and chromic acid. A sulfuric acid-phosphoric acid-sodium chloride bath-hydrochloric acid bath is known as a bath that does not use these harmful substances. However, although this bath produces a glossy surface when annealed, the processed product lacks luster, and when the shape becomes complex, the concave areas do not become glossy and become cloudy. moreover,
Because it uses a four-component system of sulfuric acid, phosphoric acid, sodium chloride, and hydrochloric acid, it has the disadvantage that the bath is complex and maintenance is difficult. The present invention has been made in view of the above-mentioned drawbacks, and provides an electrolytic etching bath that does not use harmful substances such as cyanide or chromic acid, and can provide a glossy surface regardless of whether the product is annealed, processed, or electroformed. It is. The electrolytic etching bath in the present invention is a bath consisting of acetic acid, hydrochloric acid, and water, each having a volume ratio of (a) water: (hydrochloric acid + acetic acid) = 1:0.1 to 100, and (b) It is characterized by a relationship of hydrochloric acid:acetic acid=1:1 to 10. In the present invention, the most significant feature is acetic acid. In other words, in a bath of hydrochloric acid and water, no gloss was obtained, but as the acetic acid concentration in the system was increased,
The gloss improves as the bath resistance increases. However, if the acetic acid concentration of the system becomes too high, the degree of cloudiness in the resistive current density portion of the recessed portion becomes severe in the case of an article with a large uneven shape, which is not practical. Here, the reason why the ratio of hydrochloric acid: acetic acid was limited to 1:1 to 10 and the ratio of water: (hydrochloric acid + acetic acid) to 1:0.1 to 100 was because, as stated above, the amount of acetic acid was This is because if the amount of acetic acid is less than 1:1, no gloss will be obtained at all, and if the amount of acetic acid is more than 1:10 (hydrochloric acid:acetic acid), the degree of cloudiness in the recesses will become severe in the case of articles with large irregularities. Also, the amount of water is water: (hydrochloric acid + acetic acid) = 1:
If it is less than 100, the etching rate will be too fast and the surface will become rough, and conversely, if the amount of water is more than water: (hydrochloric acid + acetic acid) = 1:0.1, the etching rate will be too slow and the efficiency will deteriorate. be. Examples and conventional examples will be described below. [Example 1] Rolled metal plate (No. 1) of 10 mm width x 50 mm length x 0.5 mm thickness, annealed product heat treated at 600°C for 30 minutes (No. 2), and 10 mm width x length 50mm x thickness 50μ
An electroformed product (No. 3) was created. Add this to 400% acetic acid
ml, water 12ml, hydrochloric acid 80ml bath at room temperature 30v2
Electrolytically etched for 1 minute. As a result, all of No. 1 to No. 3 were shiny. In particular, the gloss of No. 1 and No. 2 was remarkable (mirror gloss). [Conventional Example 1] Processed product (No. 4) similar to Example 1, annealed product (No.
5) Create an electroformed product (No. 6) and add it to 200 g of sodium chloride, 100 ml of sulfuric acid, and 100 g of phosphoric acid.
ml/, 500A/dm 2 at room temperature in a bath of hydrochloric acid 50ml/
Electrolytically etched for 20 seconds. Results No.4 and No.6
was shiny, but the annealed product No. 5 was not shiny. In addition, the processed product No. 4 was inferior in gloss compared to No. 1. [Example 2] Annealed products of width 10 mm x length 50 mm x thickness 5 mm (No. 7~
No. 10) was made into a cylindrical shape with a diameter of 5 mm and electrolytically etched in the same bath as in Example 1 under the conditions shown in the left column of the table below.The degree of gloss and the amount of etching in the cloudy state were examined, and the results shown in the right column of the table below were obtained. .
【表】
ここで◎は鏡面光沢を示す。
〔実施例 ３〕
次に、実施例２と同様の純鈍品（No.11〜No.16）
を実施例１と同様な浴で、5A，30Vでエツチン
グ時間を変化させたところ下表の結果を得た。[Table] Here, ◎ indicates specular gloss.
[Example 3] Next, pure blunt products similar to Example 2 (No. 11 to No. 16)
When the etching time was varied at 5 A and 30 V using the same bath as in Example 1, the results shown in the table below were obtained.
〔実施例 ４〕[Example 4]
次に実施例２と同様の加工品（No.17〜No.19）を
実施例１と同様な浴で、下表右欄の条件で行つた
ところ下表左欄の結果を得た。
〔従来例 ２〕
実施例２と同一形状の加工品（No.20）を従来例
１と同様な浴で、下表右欄の条件で行つたところ
下表左欄の結果を得た。
Next, the same processed products (No. 17 to No. 19) as in Example 2 were treated in the same bath as in Example 1 under the conditions shown in the right column of the table below, and the results shown in the left column of the table below were obtained. [Conventional Example 2] A processed product (No. 20) having the same shape as in Example 2 was treated in the same bath as in Conventional Example 1 under the conditions shown in the right column of the table below, and the results shown in the left column of the table below were obtained.
〔実施例 ５〕[Example 5]
次に実施例２と同様の加工品（No.21〜No.23）を
酢酸200ml，塩酸100ml，水200mlの浴に浸漬し、
下表右欄の条件で行つたところ下表左欄の結果を
得た。
Next, processed products similar to those in Example 2 (No. 21 to No. 23) were immersed in a bath of 200 ml of acetic acid, 100 ml of hydrochloric acid, and 200 ml of water.
When the test was carried out under the conditions shown in the right column of the table below, the results shown in the left column of the table below were obtained.
〔実施例 ６〕[Example 6]
酢酸を300ml，塩酸100ml，水を100mlとした他
は実施例５のNo.21と同様な条件で加工品（No.24）
及び電鋳品（No.25）を行つたところ、外側光沢が
◎，内側曇りが無く、エツチング量が7.7μ
（0g074）という結果を得た。
〔実施例 ７〕
実施例６と同一組成条件の浴でK18の金−銀−
銅合金指輪を電解エツチングしたところ（２cm2，
400A／ｄm2，60秒）外側光沢が鏡面光沢であり
内側曇りは無かつた。
以上の実施例から明らかなように、本発明によ
れば従来浴に比し、以下のような利点を有する。
本発明浴では従来浴では得られない圧延加工
等の金又は金合金の加工品についても鏡面光沢
を出すことができるので、指輪，ブレスレツ
ト，ペンダント，ブローチ，腕時計の側や枠，
めがねつる等の装飾品に最適な電解エツチング
浴である。
本発明浴は従来浴に比し、電流が流れにくい
電解条件の悪い部分についても曇りが少ないの
で、ロストワツクス法による鋳造品や金の厚め
つきによる電鋳品などの複雑な形状の品物にも
均一に電解エツチングすることができる。
本発明浴は従来浴に比し、浴抵抗が低いの
で、消費電力も少なくまた、浴温度の上昇も少
ない。したがつて、多量生産しても温度上昇に
よる水分の蒸発浴組織の変化が少なく、安定し
たエツチング浴となる。
さらに、本発明浴は次の特徴を有する。
本発明浴では、電流密度が大きい程光沢が良
くなるが、逆に大きくなりすぎると電流密度分
布のばらつきが激しくなり、いわゆる陰の部分
（低電流密度部分）で曇りやすくなる。そのた
め複雑な形状の装飾品を電解エツチングすると
きはあまり高くなる電流密度で行う。
本発明浴では、エツチング時間が長い程、光
沢は良くなるが、長くなればと同じように陰
の部分で曇りやすくなる。したがつて、エツチ
ング形状によつてエツチング時間を考慮する必
要がある。
本発明浴では、酢酸濃度が薄くなり浴抵抗が
下がると陰の部分の曇り度合は減少し、酢酸濃
度が濃くなり浴抵抗が上がると光沢が良くなる
傾向にある。
Processed product (No. 24) under the same conditions as No. 21 in Example 5, except that 300 ml of acetic acid, 100 ml of hydrochloric acid, and 100 ml of water were used.
and electroformed product (No. 25), the outer gloss was ◎, there was no clouding on the inner side, and the etching amount was 7.7μ
I got the result (0g074). [Example 7] K18 gold-silver in a bath with the same composition conditions as Example 6
Electrolytically etched copper alloy ring (2cm 2 ,
(400 A/dm 2 , 60 seconds) The outer gloss was specular and there was no inner haze. As is clear from the above examples, the present invention has the following advantages over conventional baths. With the bath of the present invention, it is possible to produce a specular luster on gold or gold alloy processed products such as rolled ones, which cannot be obtained with conventional baths, so it can be used on rings, bracelets, pendants, brooches, the sides and frames of watches, etc.
This electrolytic etching bath is ideal for decorative items such as eyeglasses. Compared to conventional baths, the bath of the present invention has less clouding even in areas with poor electrolytic conditions where it is difficult for current to flow, so it can be used evenly on products with complex shapes, such as products cast by the lost wax method or electroformed products with thick gold plating. It can be electrolytically etched. Since the bath of the present invention has lower bath resistance than conventional baths, it consumes less power and causes less rise in bath temperature. Therefore, even if the etching bath is produced in large quantities, there is little change in the structure of the water evaporation bath due to temperature rise, resulting in a stable etching bath. Furthermore, the bath of the present invention has the following characteristics. In the bath of the present invention, the higher the current density, the better the gloss, but conversely, if the current density is too high, the current density distribution becomes more uneven, and the so-called shadow areas (low current density areas) tend to become cloudy. Therefore, when electrolytically etching ornaments with complex shapes, the current density is too high. In the bath of the present invention, the longer the etching time, the better the gloss, but the longer the etching time, the more likely it will become cloudy in the shadow areas. Therefore, it is necessary to consider the etching time depending on the etching shape. In the bath of the present invention, as the acetic acid concentration decreases and the bath resistance decreases, the degree of haze in the shaded area decreases, and as the acetic acid concentration increases and the bath resistance increases, the gloss tends to improve.