DE1127170B - Use of perhalocarboxylic acids as an additive to aqueous solutions for the surface treatment of metal objects - Google Patents

Description

INTERNAT.KL. C 23 g

GERMAN

PATENT OFFICE

K 29534 VIb / 48 d

REGISTRATION DAY:

NOTICE THE REGISTRATION ANDOUTPUTE EXTENSION STEP:

AUGUST 4, 1956

APRIL 5, 1962

The invention relates to the use of perhalocarboxylic acids of the formula

Cl (CF ₂ - CFClVCF ₂ - COOH

wherein ή denotes an integer from 1 to 5, and / or salts of these acids as an additive to aqueous solutions for surface treatment, in particular electroplating, pickling, etching and cleaning of metal objects.

It was already known to use chromium plating baths surface-active sulfonic acids of perfluorinated Hydrocarbons with 4 to 18 carbon atoms or their salts in amounts of at least 0.01 per liter Add bath to avoid spray and mist formation during electrolysis.

The perhalocarboxylic acids according to the invention or their salts are z. B. in electroplating baths used to control the surface tension of the bath. In these baths, the surface-active Means the formation of a foam blanket on the surface of the bath, preventing the escape of mists the treatment liquid is reduced or prevented. These surfactants also act that the metallic surfaces, which are to be provided with a coating layer, evenly moistened and that the bath acts evenly on them. The surface tension is in electroplating baths in connection with the tendency to signs of corrosion, since it is the size of the hydrogen bubbles affects which can be retained on a given surface. In general A reduction in surface tension favors the release of the vesicles and thus delays them the occurrence of corrosion phenomena.

The effective concentration of surfactants can most easily be controlled by a Determination of the surface tension according to the usual methods. With most of the determination methods a direct comparison with pure Water turned on. At a temperature of 20 ° C, the surface tension of pure water is about 73 dynes / cm and at a temperature of 100 ° C about 59 dynes / cm. In general, the Surface tension of water by about 1 dyn / cm per 5 ° C increase in temperature.

The following information relates to the surface tension of 1% strength aqueous solutions of the invention Acids compared with water and clearly show their surface-active properties.

Water 72.0 dynes / cm

CI (CF ₂ CFCI) ₂ CF ₂ Co ₂ H 41.3 dynes / cm

Use of perhalocarboxylic acids as an additive to aqueous solutions

for surface treatment

of metal objects

Applicant:

Minnesota Mining

and Manufacturing Company,

St. Paul, Minn. (V. St. A.)

Representative: ~

Dr. W. Beil and A. Hoeppener, lawyers, Frankfurt / M.-Höchst, Antoniterstr. 36

Claimed priority: V. St v. America of August 4, 1955 (No. 526 537)

William Siddall Barnhart, Cranford, N.J., and Robert Harold Wade, WestPaterson, N.J.

(V. St. Α.),
have been named as inventors

CI (CF ₂ CFCI) ₃ Cf ₂ CO ₂ H 25.4 dynes / cm

CI (CF ₂ CFCI) ₄ Cf ₂ CO ₂ H 25.0 dynes / cm

Mixed acids (C ₈ to C ₁₀ ) ... 25.0 dynes / cm

To prove the stability of these acids, a sample of the C ₈ acid was heated to a temperature of 200 ° C for 20 hours and a second sample was heated to a temperature of 100 ° C for 33 days. There was no apparent change in acidity in either case. At 260 ° C the acid slowly began to burn.

Surfactants in electroplating baths have one or more of the following effects:

1. They facilitate the even deposition of metal,

2. they reduce the appearance of corrosion,

3. they clean insufficiently cleaned surfaces,

4. They minimize losses due to entrainment,

5. they increase the smoothness and brightness of the surfaces,

209 558/415

10

6. they reduce the porosity of the coating metal,

7. they reduce the splashing of the electrolyte,

8. they refine the grain structure and increase the hardness,

9. They expand the working areas in terms of temperature, pH and current density,

10. They control the anode efficiency, and

11. They improve the adhesive strength of the coatings the base metal.

In addition to these effects, those according to the invention have Perhalocarboxylic acids or their salts have the following benefits:

1. No chemical degradation or reaction with

Loss * 5 H ₂ SO ₄ of acids or salts _{due to the electroplating bath, HNO 3}

2. No to degradation or reaction of the surface-active ones Agents attributable to harmful effects on the bathroom or the surface of the Metal coating,

3. Certain desirable electroplating properties, which result from the special nature of the surface-active Funds yield, and

4. high thermal stability, which allows the use of the surfactant even at high Bath temperatures permitted.

the brass and eliminate any tendency of the pickling solution to attack the metal in certain places. These acids also have the advantage that they do not cause the frequently occurring and undesirable color clouding permit.

The following baths are suitable for pickling Brass:

Dipping bath for the removal of oxide layers at 20 to 4O ⁰ C

HCl

Perchlorofluorocarboxylic acid

specific weight

1.84 1.38 1.17

g / l

700

100

544

0.01 to 5, preferably 0.3

Immersion for lightening at 20 to 4O ⁰ C

Metals based on base metals using the surfactants of the present invention Can be plated are cadmium, cobalt, copper, lead, tin, zinc and chromium. Although the invention Perhalocarboxylic acids or their salts in some cases from solutions containing metal ions are precipitated, however, this is not of practical importance since a sufficient amount of the surfactant remains in the solution to give the bath the desired properties.

The perhalocarboxylic acids or their salts can also be used with advantage in cleaning and pickling solutions can be used because the production of an impenetrable, firmly adhering metal coating in depends primarily on having a perfectly clean surface on the metal being plated is present. The metal surfaces are often replaced by oxides, e.g. B. rust and fat or oil or other organic Contaminated substances.

Fats, oils and similar substances are removed either by treatment with hot alkali, e.g. B, caustic soda or caustic potash, or by treatment with suitable organic solvents such as gasoline, benzene, Carbon tetrachloride, among others, removed. The removal of oxides, among others. is often done by pickling with an acid, this depending on the type of metal and the oxide coating to be removed from it is selected. Generally used for iron and Steel uses sulfuric or hydrochloric acid, occasionally hydrofluoric acid, while for brass Sulfuric and nitric acid can be used. Here, the perhalocarboxylic acids have in pickling baths the advantage that the oxide layer is removed more easily, more completely and in a shorter time. The acids will also not destroyed by the oxidizing baths, and that which can be traced back to entrainment Loss can be compensated for in the following washes.

When cleaning brass, the perhalocarboxylic acids favor a uniform attack on

H ₂ SO ₄

ENT ₃

HCl

H ₂ O ......

Perchlorofluorocarboxylic acid

35 Specific weight

1.84 1.38 1.17

g / l

800

100 25

493

0.1 to 5, preferably 0.5

When pickling iron and steel, it is extremely important to check the effect of the pickling on their physical properties Properties and especially the brittleness of the metal, as it is known that Steel, especially tempered spring steel, can become very brittle through pickling. During pickling Hydrogen develops on the surface of the steel and it is probable that the brittleness related to the uptake of hydrogen in some form by the metal. Perchlorofluorocarboxylic acids prove to be advantageous here because they reduce the amount of hydrogen on the metal surface and because the acid solution can also be heated to achieve a high level of effectiveness. A Another advantage resulting from the use of perchlorofluorocarboxylic acids is that the oxide deposit can be removed more quickly and easily, with less iron or steel loss and at the same time the pickling acid is retained. The perchlorofluorocarboxylic acids also reduce the amount of splashed liquid, which is carried away from the bath by the developing hydrogen. A common sulfuric acid pickle contains per liter

So bath liquid 100 g sulfuric acid and 0.01 to 5 g, preferably 0.3 g, perchlorofluorocarboxylic acid. This bath can, if desired, be heated and is normally operated at a temperature of about 5O ⁰ C. The pickling time can be about 10 minutes to about 1 hour or more.

A common hydrochloric acid pickling solution contains 73 g of hydrogen chloride and about 0.01 to 5 g per liter of bath liquid, preferably 0.3 g, perchlorofluorocarboxylic acid. This

Bad can also be applied at a temperature of about 5O ⁰ C.

Hydrofluoric acid is mainly used in iron castings with grains of sand in the surface can be embedded, which must be removed prior to treatment, should be stained. Sand inclusions can also occur in steel that has been treated with a sand blower under too high pressure occurrence. A common hydrofluoric acid pickle contains 40 g of hydrogen fluoride per liter of bath liquid, 2 g sulfuric acid and 0.01 to 5 g, preferably 0.3 g, perchlorofluorocarboxylic acid. The temperature and time of pickling can be very different.

Perchlorofluorocarboxylic acids have also proven useful in the whitening dipping process for cadmium coatings. A suitable bath contains 20 g chromic acid, 0.14 g sulfuric acid (specific Weight 1.84) and 0.1 to 2 g of a perchlorofluorocarboxylic acid. The immersion can take about 20 to 30 seconds last.

Dip solutions for the pretreatment of aluminum prior to copper plating also advantageously contain them Perchlorofluorocarboxylic acids. A common bathroom solution is composed as follows:

Sodium hydroxide 400 g / l

Zinc oxide 80 g / l

Potassium copper (I) cyanide,. 2 g / l

Sodium sulfite 25 g / l

Perchlorofluorocarboxylic acid 0.2 g / l

It is also advantageous to use perchlorofluorocarboxylic acids in etching processes because of the addition a small amount of such acid to the caustic has one or more of the following beneficial effects be achieved:

1. a sharper etching and a smoother surface,

2. Reduction of the adhesion of gas bubbles to the surface to be etched,

3. reducing the tendency of the accumulated gas to lift off protective or reserve layers,

4. Cleaning the surface of substances during the reaction fail, e.g. B. Copper deposits on zinc surfaces from copper salt solutions,

5. Increase in. Reaction speed and thus less impairment of the reserve layer,

6. Reduction of splashing and spraying,

7. Reduction of the excess liquid adhering to the product when it is in the etching bath is removed, thereby preventing unwanted dripping of liquid on the Equipment and its surroundings,

8. uniform effect of the etchant on the too corrosive surface,

9. no loss of perchlorofluorocarboxylic acid through chemical reaction or degradation and

10. No harmful effects on the bath or the etched surface, which can be attributed to the degradation or the _6ö reaction of perchlorofluorocarboxylic acid.

Cadmium metal 19 to 34 g / l,

preferably 25 g / l, ■

Sodium cyanide 86 to 131 g / l,

preferably 110 g / l, salt of

Cl (CF ₂ -CFCl) _n CF ₂ COOH .. 0.01 to 0.5g / l,

. preferably 0.1 g / l η = 2 to 5

ίο The electroplating is carried out at 20 to 35 ° C, using either cadmium or steel anodes with a current density of 0.018 to 0.02 A / cm ² .

example 1

A cadmium electroplating bath has the following composition:

Cadmium oxide 23 to 29 g / l,

preferably 25 g / l,

Example 2

A cobalt plating bath has the following composition on:

, CoiNHJaiSO ^ · 6H ₂ O 175 g / l

Ammonium acetate 26 g / l

Acetic acid 1.0 g / l

Formalin (38% CH ₂ O) 2.6 g / l

Cadmium sulfate 0.18 g / l

Salt from

CI (CF ₂ -CFCI) ₅₁ Cf ₂ COOH 0.01 to 0.5 g / l,

preferably 0.05 g / l η = 2 to 5

The electroplating is carried out at a temperature of up to 35 ° C using cobalt anodes and a current density of 0.02 to 0.15 A / cm ² .

Example 3

A copper electroplating bath has the following composition:

A. Copper (I) cyanide: 19 to 45 g / l,

preferably 26 g / l sodium cyanide 26 to 53 g / l,

preferably 35 g / l sodium carbonate 15 to 60 g / l,

preferably 30 g / l Rochelle salt
(KNaC ₄ H ₄ O ₆ · 4H ₂ O) 30 to 60 g / l,

preferably 45 g / l copper 15 to 30 g / l,

preferably 19 g / l salt of

Cl (CF ₂ -CFC1) «CF ₂ COOH 0.01 to 1.0 g / l,

preferably 0.5 g / l η = 2 to 5

pn 12.2 to 12.8,

preferably 12.6

Sodium hydroxide is added to this solution until the pH is 12.6. The electroplating is carried out at a temperature of 50 to 80 ° C using copper anodes and a current density of 0.018 to 0.075 A / cm ² .

B. Copper fluoroborate 224 to 448 g / l,

preferably 335 g / l

Fluoroboric acid 15 to 30 g / l,

preferably 22 g / l

Boric acid 15 to 30 g / l,

preferably 22 g / l salt of

Cl (CF ₂ -CFC1) "CF ₂ COOH 0.01 to 1 g / l,

preferably 0.1 g / l η == 2 to 5

1

During electroplating, copper anodes are used with a current density of 0.04 to 0.05 A / cm ² at a temperature of 32 to 43 ° C.

Example 4

A lead electroplating bath has the following composition:

Basic lead carbonate 150 g / l

50 ° / _o strength hydrofluoric acid .. 240 g / l

Boric acid '. .. 106 g / l

• Glue ...: 0.2 g / l

Salt from

Cl (CF ₂ -CFC1) "CF ₂ COOH 0.01 to 0.5 g / l, _lg

preferably 0.1 g / l M = 2 to 5

During electroplating lead anodes are used with a current density from 0.005 to 0.075 A / cm ² at _ao a temperature of 25 to 40 ° C. The current density to be used is determined by the thickness of the desired deposit.

Example 5

A tin electroplating bath has the following composition:

Tin (II) sulphate 30 to 90 g / l, see above

preferably 60 g / l

Sulfuric acid 30 to 150 g / l,

preferably 75 g / l

Sodium sulfate

(Na ₂ SO ₄ · 10H ₂ O) .......... 50 to 300 g / l,

"preferably 150 g / l

/ S-naphthol 0.5 to 1.0 g / l,

preferably 0.5 g / l

Salt from

Cl (CF ₂ -CFCl) _n CF ₂ COOH 0.01 to 1.0 g / l, * ° : preferably 0.1 g / l

η = 2 to 5

45

The temperature of the solution is maintained at 20 to 30 ° C. with a current density of 0.01 to 0.04 ^{Å / cm 2} using tin anodes. This bath must contain additives, otherwise the plating will become loose, crystalline and tree-shaped.

Example 6

The following composition is given for a zinc electroplating bath;

Zinc sulphate (Zn SO ₄ · 7 H ₂ O) ... 240 g / l

Ammonium chloride 15 g / l

Ammonium sulfate

[Al ₂ (SO ₄ ) S · 8H ₂ O] 30g / l

Salt from

Cl (CF ₂ -CFCl) _n CF ₂ COOH 0.01 to 0.5g / l,

preferably 0.1 g / l η - 2 to 5

Anodes made of lead alloy or silicon iron are used, and electroplating is carried out at a temperature of 24 to 30 ° C at a current density of 0.01 to 0.03 A / cm ² .

55

60

170

-Example 7

The following etching solutions are given as examples, the salts of perehlorofluorocarboxylic acids contain:

I. zinc

1. 20% copper sulfate solution

(CuSO ₄ .- 5H ₂ O) 75 to 150 ml,

preferably 95 ml

35 ^a / _o ige sodium bisulphate solution 0.5 to 10 ml,

preferably 5 ml of salt of

Cl (CF ₂ -CFCl) _n CF ₂ COOH 0.001 to 0.5 g,

preferably 0.02 g η = 2 to 5

2. 42 ° / ₀ sodium iron (III) chloride

solution .. 45 to 75 ml,

preferably 60 ml

28% acetic acid 10 to 45 ml,

preferably 15 ml

9% ig ^e nitric acid 10 to 45 ml,

preferably 15 ml

Chromic acid solution with 0.02 to 0.05 g,

. 'CrOs content

preferably 0.03 g salt of

Cl (CF ₂ -CFCl) _n CF ₂ COOH 0.001 to 0.5g,

preferably 0.02 g η = 2 to 5

II. Iron and steel

Smoking nitric acid .... 5 to 15 ml,

preferably 10 ml

30% acetic acid 25 to 75 ml,

preferably 50 ml

Water 0 to 1000ml,

preferably 40 ml

Salt from

Cl (CF ₂ - CFCl) ₁₁ CF ₂ COOH 0.001 to 0.5 g,

preferably 0.02 g

η = 2 to 5

III. Copper and brass

30% hydrogen peroxide ^it ig .. 5 to 15 ml, preferably 10 ml

Conc. Ammonium hydroxide .. 30 to 60 ml, preferably 50 ml

Salt of CI (CF ₂ -CFCI) ₅₁ Cf ₂ COOH 0.001 to 0.5 g,

preferably 0.01 g

η = 2 to 5

IV. Aluminum and aluminum alloys

Conc. Hydrochloric acid 40 to 60 ml,

preferably 45ml conc. nitric acid 10 to 20 ml,

preferably 15 ml of 50% hydrofluoric acid 10 to 20 ml,

preferably 15 ml water 10 to 50 ml,

preferably 25 ml of salt of

Cl (CF ₂ - CFCl) ₅₁ CF ₂ COOH 0.001 to 0.5 g,

preferably 0.02 g B = 2 to 5

Claims (1)

9 10 V. Nickel and nickel alloys 70 ° / ₀ nitric acid; 40 to 60ml, PATENT CLAIMS: preferably 50ml 1. Use of perhalocarboxylic acids 50% strength acetic acid ^e 40 to 80 ml, formula preferably 50 ml 5 Salt of Cl (CF ₂ - CFQ). · CF ₂ · COOH
Cl (CF ₂ - CFCl) _re CF ₂ COOH 0.001 to 0.5 g, preferably 0.02 g in which η is an integer from 1 to 5, η = 2 to 5 and / or salts of these acids as an additive τγτ ^ υ o-it. r.1 * λ α Τ2Λ ι ν. Ii ¹⁰ aqueous solutions for surface treatment, VI. Gold, silver, platinum and other precious metals in particular electroplating, pickling, etching and Conc. Nitric acid 8 to 15 ml, cleaning of metal objects. preferably 10 ml 2. Use of the perhalogenic acids according to Conc. Hydrochloric acid 40 to 75 ml, Spruch 1, in an amount of 0.001 to 5 g, before- preferably 50 ml, preferably 0.01 to 0.1 g, per liter of treatment water 50 to 75 ml, liquid. preferably 60 ml Salt from CI (Cf ₂ -CFCI) ₅₁ CF ₂ COOH 0.001 to 0.5g, publications considered: preferably 0.02 g 20 A. Chwalla: “TextühUfsmittel 1939, p. 107 to 117; η = 2 to 5 "Seifen, Öle, Fette, Wachse", 1951, p. 182. © 209 558/415 3.62