EP3339481A1 - Method and kit of parts for the pretreatment of objects to be chromed - Google Patents

Abstract

The invention relates to a method for the production of chrome-plated articles. The method is characterized in that an object to be chromium-plated is contacted before chromium plating with at least one aqueous sink containing at least one surfactant or a mixture of surfactants and an acid or a mixture of acids. The invention further relates to a kit-of-parts for addition to at least one sink in front of a chromium bath, wherein the kit-of-parts comprises as the first constituent an acid or a mixture of acids and as second constituent a surfactant or a mixture of surfactants. Both the process and the application of the kit-of-parts serve to avoid chromium stains.

Description

The invention relates to a method for the production of chrome-plated articles.

The invention further relates to a kit-of-parts for addition to one or more rinses in front of a galvanic chrome bath.

Introduction and state of the art

During the galvanic chrome plating of objects, impairments, the so-called "chrome spots", which are also referred to as "white wash", "cloudy chromium deposits" and the like, can occur. These impairments occur particularly in the chrome-plating of bright nickel-plated objects, in particular in the bright chrome plating of brightly nickel-plated objects. These impairments are identified in a variety of ways, for example as gray to white spots, as gray-black ("burn-like") deposits or as colorful ("rainbow-like") deposits.

For the purposes of the present invention, the term "chrome stains" is understood to mean defects on the chromium surface based on white-wash, stinging-like and rainbow-like deposits.

Basics of electroplating are treated in various textbooks, whereby the books " Galvanic Plating "by Robert Brugger (published in the Eugen G. Leuze publishing house in Saulgau / Württ in 1967 with Prof. Dr.-Ing. Robert Weiner as publisher ) and " Galvanic plating "by GA Lausmann and JNM Unruh (the first edition was published by Eugen G. Leuze Verlag in Saulgau / Württ., In 1998 ) should serve as examples.

One way to avoid the mentioned chromium spots is an activation of the object to be chrome plated immediately before chromium plating by means of a chromic acid activation, which takes place in a chromic acid-containing bath. However, the future viability of this step is at least due to planned tightening of legislation in connection with Cr (VI) compounds questionable within the European Union. Therefore, chromic acid-free alternatives are being researched and a possibility for Cr (VI) -free activation of items to be chromed is highly desirable.

Other ways to avoid this impairment are specific settings, which mainly relate to the specifications of nickel and chrome bath, in particular the sulfate content of the chromium bath and the brightening additive content of the nickel bath.

• So offenbart US 2014/127532 A das Problem von "surface clouding" beim Abscheiden von Chrom auf Nickel und vermeidet das Problem durch das Abscheiden einer weiteren Metallschicht - einer Sn/Ni Legierung - zwischen der Nickel- und der Chromschicht.

However, other avoidance strategies are also disclosed:

• So revealed US 2014/127532 A the problem of "surface clouding" in the deposition of chromium on nickel and avoids the problem by depositing another metal layer - an Sn / Ni alloy - between the nickel and the chromium layer.

US 3,788,957 addresses the problem of chromium stains and avoids it by using cationic surfactants as an additive to the chromium bath.

Also US 4,865,700 discloses the avoidance of "chrome wash"("whitewash" or "cloudy chromium deposits"), which is achieved by specific adjustments in the chrome bath.

Galvanotechnik (1996) No. 10, pp. 3302-3303 deals with various measures to avoid chrome spots that occur during chrome plating of shiny nickel-plated objects. The following measures, in this case pertain to the sink between the nickel and the chrome bath or directly in front of the chrome bath. On the one hand, the use of rinses with clean rinse water is proposed, whereby clean rinse water means water without "entrained" from the nickel bath, organic impurities, such as surfactants and brighteners. Also, a shortening of the residence time between rinsing and chrome bath is considered advantageous. As a further measure, activation in 30% sulfuric acid is recommended.

In two further articles ( Galvanotechnik (2005), No. 1, pp. 136-137 and Galvanotechnik (2011), No. 4, pp. 847-848 ), various measures for the prevention of chrome stains, which occur during the chrome plating of bright nickel objects, called. On the one hand, the use of deionized water as flushing water in front of the chrome bath is considered a source of problems for the formation of Chromium spots and instead recommended the use of normal tap water. On the other hand, impurities in the rinsing water such as surfactants, organic substances and ions as well as the pH of the rinsing water are mentioned as causes of the chromium staining. It is recommended to operate a rinse bath as free as possible of organic contaminants at a maximum of 30 ° C and a pH of about 6.

The previously described measures known from the prior art for reducing or avoiding chrome stains, in particular for bright chrome plating on glossy nickel-plated objects, are unsatisfactory or can be improved from an ecological point of view.

task

The object of the present invention is thus to develop a new method for preventing chromium stains in the galvanic chrome plating of objects, in particular in the chrome plating or bright chrome plating of glossy nickel-plated objects.

1. a) in Kontakt bringen eines zu verchromenden Gegenstandes mit einer oder mehreren Spülen, wobei mindestens eine dieser Spülen eine wässrige Spüle, enthaltend
   1. a. mindestens ein Tensid oder mindestens eine Mischung von Tensiden und
   2. b. mindestens eine Säure oder mindestens eine Mischung von Säuren;
      ist; und
2. b) galvanisches Verchromen des Gegenstandes in einem Chrombad.

This object is achieved by a method for producing chrome-plated articles, which is characterized by the following method steps

1. a) bringing into contact a chrome-plated article with one or more rinses, wherein at least one of these rinses an aqueous sink containing
   1. a. at least one surfactant or at least one mixture of surfactants and
   2. b. at least one acid or at least one mixture of acids;
      is; and
2. b) electroplating the article in a chromium bath.

For the purposes of the present invention, objects to be chromium-plated are objects that are suitable for the chrome-plating of those skilled in the art. This includes items made of iron, steel, stainless steel, nickel, copper, plastic (such as ABS), non-ferrous metal, bronze and alloys of the materials mentioned.

Such a method of treating articles prior to chrome plating to avoid staining of chrome has neither been described nor suggested in the current state of the art.

Thus, the already cited prior art, which explicitly deals with the avoidance of chrome stains, does not disclose that the chromium stains can be avoided by rinsing upstream of the chromium bath (see US 2014/127532 A . US 3,788,957 and US 4,865,700 ), or does not disclose that at least one of these rinses to contain both an acid (or a mixture of acids) and a surfactant (or a mixture of surfactants), but leads the skilled artisan away from the invention invention since The presence of surfactants in the sinks in front of the chrome bath is explicitly avoided (see the three quoted "Electroplating" writings: Galvanotechnik (1996) No. 10, pp. 3302-3303 . Galvanotechnik (2005), No. 1, pp. 136-137 and Galvanotechnik (2011), No. 4, pp. 847-848 ).

Further state of the art, which deals with the constitution of rinsing upstream of the chrome bath ( EA 200 501 610 A and EP 1 876 268 A ) does not disclose that the rinses have to contain both an acid (or mixture of acids) and a surfactant (or mixture of surfactants) to avoid chromium stains.

So revealed EA 200 501 610 the use of surfactants in the sink in front of the chrome bath. However, the simultaneous presence of acid is not disclosed or suggested. Furthermore, there is no connection between the teachings of this patent and the avoidance of chrome stains.

In EP1876268 For example, cathodic activation takes place before chromium plating, and this activation can optionally also be carried out in the presence of acids and surfactants. However, there is no indication that this pretreatment prevents chrome stains and even less that this pretreatment could also occur de-energized and prevent chromium stains.

The method according to the invention is particularly suitable for chromium plating, as well as for bright chrome plating of glossy nickel-plated objects.

In a preferred embodiment of the method according to the invention, therefore, a bright nickel layer is electrodeposited on the article to be chromium-plated before process step a).

Bright nickel layers within the meaning of the invention are nickel layers known from the literature. They are obtained, for example, by the methods disclosed in the following documents and the publications cited therein. These writings are: DE 1 005 803 B . DE 848 890 C . DE 1 063 003 B . DE 931 623 C . DE 10 2014 207 778 A ,

The rinses according to the invention in step a) preferably comprise cascade rinsing, stationary rinsing or flow rinsing. Also, other, familiar to the expert, rinsing such as spray rinses, recirculation rinses, Kreislauffließspülen or high pressure rinsing, and combinations of all mentioned rinses are included, wherein the rinsing of the invention may also be different when using multiple rinses.

Rinses according to the invention are preferably aqueous rinses.

In a further preferred embodiment of the process according to the invention, the temperature of the rinses is from 5 to 80.degree. C., preferably from 10 to 60.degree. C., more preferably from 15 to 50.degree. C., particularly preferably from 20 to 40.degree.

In a further preferred embodiment of the process according to the invention, the bringing into contact in step a) takes 5 to 900 seconds, preferably 10 to 600 seconds, more preferably 30 to 300 seconds. However, contact times of several hours are also possible.

The mixture according to the invention of at least one surfactant or at least one mixture of surfactants and at least one acid or at least one mixture of acids, which is used in process step a), is hereinafter abbreviated to "acid-surfactant mixture".

In a further preferred embodiment of the method according to the invention, the aqueous solution in the rinses is stationary or non-stationary in relation to the chrome-plated article and / or the articles to be chrome-plated are stationary or non-stationary in relation to the aqueous solution. In another In the preferred embodiment, at least one aqueous solution in the rinses is not stationary relative to the chrome-plated article and / or the articles to be chrome-plated are not stationary in relation to the aqueous solution of at least one rinse. More preferably, at least one acid-surfactant mixture of at least one sink is not stationary in relation to the chromium-plated article and / or the articles to be chromium-plated are not stationary in relation to at least one acid-surfactant mixture.

The relative movement of the object to the sink is preferably achieved by a movement of the object or a movement of the liquid of the sink, wherein the movement of the liquid can also be effected by blowing in air.

In a preferred embodiment of the process according to the invention, the acid-surfactant mixture according to the invention is in the last rinse in front of the chromium bath. The last sink in front of the chrome bath here means the sink, with which the object to be chromed is contacted before the chrome bath last.

The total concentration of the surfactants of the acid-surfactant mixture in a further preferred embodiment of the process according to the invention in at least one rinse is from 0.5 to 50 g / L, preferably from 0.75 to 8 g / L, more preferably from 1 to 5 g / L, wherein the concentration in the use of more than one sink in these rinses may be different or may be 0 g / L, if in another sink, the surfactant concentration is preferably in one of the aforementioned ranges.

In a further preferred embodiment of the process according to the invention, the surfactants of the acid-surfactant mixture are selected from the group of anionic surfactants.

In a further preferred embodiment of the process according to the invention, the anionic surfactants of the acid-surfactant mixture are selected from the group consisting of alkyl sulfates, aryl sulfates, alkyl sulfonates, aryl sulfonates, alkyl phosphonates, aryl phosphonates, alkyl phosphates, aryl phosphates, alkyl ether sulfates, aryl ether sulfates, alkyl carboxylates, aryl carboxylates, alkyl ether sulfonates, Aryl ether sulfonates and their fluorinated and perfluorinated analogs and mixtures thereof.

In a particularly preferred embodiment of the process according to the invention, at least one surfactant of the acid-surfactant mixture has at least one sulfur-oxygen bond.

In a further particularly preferred embodiment of the process according to the invention, the surfactants of the acid-surfactant mixture are selected from the group consisting of octyl sulfate, decyl sulfate, lauryl sulfate, perfluoroheptane sulfate, perfluorohexane sulfate, perfluorooctane sulfate, perfluorodecane sulfate, hexylpoly (oxyethylene) sulfate, octylpoly (oxyethylene) sulfate decylpoly (oxyethylene) sulfate, lauryl ether sulfate, polyethylene glycol alkyl (3-sulfopropyl) diether and polyethylene / propylene glycol (beta-naphthyl) (3-sulfopropyl) diether. Lauryl ether sulfate, lauryl sulfate, polyethylene glycol alkyl (3-sulfopropyl) diether, and polyethylene / propylene glycol (beta-naphthyl) (3-sulfopropyl) diether are even more preferred.

The counterions of the anionic surfactants of the acid-surfactant mixture are preferably monovalent or divalent ions. Particularly preferred are monovalent ions. Particular preference is given to monovalent ions selected from the group consisting of ammonium, lithium, sodium and potassium or the triethanolamine salts of the surfactants.

In the context of the present invention, the acids of the acid-surfactant mixture according to the invention are, in particular, chromium-compatible acids. Chromium-compatible acids in the context of the invention are those acids which would be used by the person skilled in the art in galvanic chrome baths or which would be added to galvanic chromium baths. Chromium-compatible acids should not impair the function of the chromium bath. In a preferred embodiment of the process according to the invention, the acids used in the acid-surfactant mixture are selected from the group consisting of boric acid, diatomaceous acid, hydrofluoric acid, sulfuric acid, methanesulfonic acid, methanedisulfonic acid and mixtures of said acids. In one embodiment, chromic acid is excluded.

In a further preferred embodiment of the process according to the invention, the pH in at least one rinse containing the acid-surfactant mixture is less than 2.0, preferably less than 1.7, more preferably less than 1.5, the pH being Value in using more than one sink containing the acid-surfactant mixture may be different in these rinses.

In a preferred embodiment of the process according to the invention, the acids are selected from the group of silicic acid and sulfuric acid and the surfactants are selected from the group of lauryl ether sulfate, lauryl sulfate, polyethylene glycol alkyl (3-sulfopropyl) diether and polyethylene / propylene glycol (beta-naphthyl) (3 sulfopropyl) diether.

Further preferred are combinations of sulfuric acid with lauryl sulfate. Further preferred are combinations of sulfuric acid with lauryl ether sulfate. Further preferred are combinations of sulfuric acid with polyethylene glycol alkyl (3-sulfopropyl) diether. Further preferred are combinations of sulfuric acid with polyethylene / propylene glycol (beta-naphthyl) (3-sulfopropyl) diether. Further preferred are combinations of sulfuric acid with lauryl sulfate and lauryl ether sulfate. Further preferred are combinations of sulfuric acid with lauryl sulfate and polyethylene glycol alkyl (3-sulfopropyl) diether. Further preferred are combinations of sulfuric acid with lauryl sulfate and polyethylene / propylene glycol (beta-naphthyl) (3-sulfopropyl) diether. Further preferred are combinations of sulfuric acid with lauryl sulfate, lauryl ether sulfate and polyethylene glycol alkyl (3-sulfopropyl) diether. Further preferred are combinations of sulfuric acid with lauryl sulfate, polyethylene glycol alkyl (3-sulfopropyl) diether and polyethylene / propylene glycol (beta-naphthyl) (3-sulfopropyl) diether. Further preferred are combinations of sulfuric acid with lauryl sulfate, lauryl ether sulfate and polyethylene / propylene glycol (beta-naphthyl) (3-sulfopropyl) diether. Further preferred are combinations of sulfuric acid with lauryl sulfate, lauryl ether sulfate, polyethylene glycol alkyl (3-sulfopropyl) diether and polyethylene / propylene glycol (beta-naphthyl) (3-sulfopropyl) diether. Further preferred are combinations of sulfuric acid with lauryl ether sulfate and polyethylene glycol alkyl (3-sulfopropyl) diether. Further preferred are combinations of sulfuric acid with lauryl ether sulfate and polyethylene / propylene glycol (beta-naphthyl) (3-sulfopropyl) diether. Further preferred are combinations of sulfuric acid with lauryl ether sulfate, polyethylene glycol alkyl (3-sulfopropyl) diether and polyethylene / propylene glycol (beta-naphthyl) (3-sulfopropyl) diether. Further preferred are combinations of sulfuric acid with polyethylene glycol alkyl (3-sulfopropyl) diether and polyethylene / propylene glycol (beta-naphthyl) (3-sulfopropyl) diether. Further preferred are combinations of Kieselflußsäure with lauryl sulfate. Further preferred are combinations of pebble flow acid with lauryl ether sulfate. Further preferred are combinations of Kieselflußsäure with polyethylene glycol alkyl (3-sulfopropyl) diether. Further preferred are combinations of diatomaceous acid with polyethylene / propylene glycol (beta-naphthyl) (3-sulfopropyl) diether. Further preferred are combinations of pebble flow acid with lauryl sulfate and lauryl ether sulfate. Further preferred are combinations of Kieselflußsäure with lauryl sulfate and polyethylene glycol alkyl (3-sulfopropyl) diether. Further preferred are combinations of diatomaceous acid with lauryl sulfate and polyethylene / propylene glycol (beta-naphthyl) (3-sulfopropyl) diether. Further preferred are combinations of Kieselflußsäure with lauryl sulfate, lauryl ether sulfate and polyethylene glycol alkyl (3-sulfopropyl) diether. Further preferred are combinations of diatomaceous acid with lauryl sulfate, polyethylene glycol alkyl (3-sulfopropyl) diether and polyethylene / propylene glycol (beta-naphthyl) (3-sulfopropyl) diether. Further preferred are combinations of diatomaceous acid with lauryl sulfate, lauryl ether sulfate and polyethylene / propylene glycol (beta-naphthyl) (3-sulfopropyl) diether. Further preferred are combinations of diatomaceous acid with lauryl sulfate, lauryl ether sulfate, polyethylene glycol alkyl (3-sulfopropyl) diether and polyethylene / propylene glycol (beta-naphthyl) (3-sulfopropyl) diether. Further preferred are combinations of Kieselflußsäure with lauryl ether sulfate and polyethylene glycol alkyl (3-sulfopropyl) diether. Further preferred are combinations of diatomaceous acid with lauryl ether sulfate and polyethylene / propylene glycol (beta-naphthyl) (3-sulfopropyl) diether. Further preferred are combinations of diatomaceous acid with lauryl ether sulfate, polyethylene glycol alkyl (3-sulfopropyl) diether and polyethylene / propylene glycol (beta-naphthyl) (3-sulfopropyl) diether. Further preferred are combinations of diatomaceous acid with polyethylene glycol alkyl (3-sulfopropyl) diether and polyethylene / propylene glycol (beta-naphthyl) (3-sulfopropyl) diether. Further preferred are combinations of Kieselflußsäure and sulfuric acid with lauryl sulfate. Further preferred are combinations of Kieselflußsäure and sulfuric acid with lauryl ether. Further preferred are combinations of Kieselflußsäure and sulfuric acid with polyethylene glycol alkyl (3-sulfopropyl) diether. Further preferred are combinations of silica and sulfuric acid with polyethylene / propylene glycol (beta-naphthyl) (3-sulfopropyl) diether. Further preferred are combinations of Kieselflußsäure and sulfuric acid with lauryl sulfate and lauryl ether sulfate. Further preferred are combinations of Kieselflußsäure and sulfuric acid with lauryl sulfate and polyethylene glycol alkyl (3-sulfopropyl) diether. Further preferred are combinations of diatomaceous acid and sulfuric acid with lauryl sulfate and polyethylene / propylene glycol (beta-naphthyl) (3-sulfopropyl) diether. Further preferred are combinations of Kieselflußsäure and sulfuric acid with lauryl sulfate, lauryl ether sulfate and polyethylene glycol alkyl (3-sulfopropyl) diether. Further preferred are combinations of diatomaceous acid and sulfuric acid with lauryl sulfate, polyethylene glycol alkyl (3-sulfopropyl) diether and polyethylene / propylene glycol (beta-naphthyl) (3-sulfopropyl) diether. Further preferred are combinations of diatomaceous acid and sulfuric acid with lauryl sulfate, lauryl ether sulfate and polyethylene / propylene glycol (beta-naphthyl) (3-sulfopropyl) diether. Further preferred are combinations of kieselfluoric acid and sulfuric acid with lauryl sulfate, lauryl ether sulfate, polyethylene glycol alkyl (3-sulfopropyl) diether and polyethylene / propylene glycol (beta-naphthyl) (3-sulfopropyl) diether. Further preferred are combinations of Kieselflußsäure and sulfuric acid with lauryl ether sulfate and polyethylene glycol alkyl (3-sulfopropyl) diether. Further preferred are combinations of diatomaceous acid and sulfuric acid with lauryl ether sulfate and polyethylene / propylene glycol (beta-naphthyl) (3-sulfopropyl) diether. Further preferred are combinations of diatomaceous acid and sulfuric acid with lauryl ether sulfate, polyethylene glycol alkyl (3-sulfopropyl) diether and polyethylene / propylene glycol (beta-naphthyl) (3-sulfopropyl) diether. Further preferred are combinations of silica and sulfuric acid with polyethylene glycol alkyl (3-sulfopropyl) diether and polyethylene / propylene glycol (beta-naphthyl) (3-sulfopropyl) diether.

Even more preferred are combinations of sulfuric acid with lauryl sulfate. Still further preferred are combinations of sulfuric acid with lauryl ether sulfate. Still further preferred are combinations of sulfuric acid and Kieselflußsäure with polyethylene glycol alkyl (3-sulfopropyl) diether. Still more preferred are combinations of sulfuric acid with polyethylene / propylene glycol (beta-naphthyl) (3-sulfopropyl) diether.

In a further preferred embodiment of the process according to the invention, the chromium bath in process step b) is a chromium (III) bath or a chromium (VI) bath, particular preference is given to aqueous chromium baths, particular preference being given to aqueous chromium (VI) baths.

In a further preferred embodiment of the method according to the invention, the chromium plating in step b) is a bright chrome plating, the layer thickness of the chromium being from 0.1 to 2 μm, preferably from 0.1 to 0.8 μm. Particularly preferred is the bright chrome plating of glossy nickel-plated objects.

1. 1) Schwefelsauer: 150 bis 400 g/L CrO₃ mit etwa 0,8 bis 1 Gew.-% Sulfat.
2. 2) Mischsauer: 150 bis 400 g/L CrO₃ mit etwa 0,3 bis 1 g/L NaF und etwa 1 bis 3 g/L H₂SO₄.
3. 3) Mischsauer: 150 bis 400 g/L CrO₃ mit etwa 0,75 bis 2 g/L H₂SiF₆ und etwa 1 bis 3 g/L H₂SO₄.

Chromium baths for bright chrome plating in the context of the invention in particular comprise baths containing chromium (VI) ions, which would normally be used by a person skilled in the art in order to obtain bright chrome layers. Basically, two types of chrome wheels can be distinguished. On the one hand sulfuric acid chromium baths which chromic acid and sulfuric acid and on the other hand Mischaure chrome baths, in addition to chromic acid and fluorides / silicone fluorides and often include sulfuric acid (see, for example Johannes Lodermeyer, Dissertation, University of Regensburg, 2006 ). As non-limiting examples, the following three bath compositions are intended to serve:

1. 1) sulfuric acid: 150 to 400 g / L CrO ₃ with about 0.8 to 1 wt .-% sulfate.
2. 2) mixing time: 150 to 400 g / L CrO ₃ with about 0.3 to 1 g / L NaF and about 1 to 3 g / LH ₂ SO ₄ .
3. 3) mixing time: 150 to 400 g / L CrO ₃ with about 0.75 to 2 g / LH ₂ SiF ₆ and about 1 to 3 g / LH ₂ SO ₄ .

1. i. eine Säure oder eine Mischung von Säuren als ersten Bestandteil,
2. ii. ein Tensid oder eine Mischung von Tensiden als zweiten Bestandteil.

The invention also relates to a kit-of-parts for addition to one or more rinses in front of a galvanic chrome bath, the kit-of-parts comprising:

1. i. an acid or a mixture of acids as the first ingredient,
2. ii. a surfactant or a mixture of surfactants as the second component.

1. a) in Kontakt bringen eines zu verchromenden Gegenstandes mit einer oder mehreren Spülen, wobei mindestens eine dieser Spülen eine wässrige Lösung, enthaltend
   1. a. mindestens ein Tensid oder mindestens eine Mischung von Tensiden; und
   2. b. mindestens eine Säure oder mindestens eine Mischung von Säuren; ist und
2. b) galvanisches Verchromen des Gegenstandes in einem Chrombad.

In particular, the kit-of-parts according to the invention is for use in a process for producing chromed articles, characterized by the following process steps:

1. a) bringing into contact a chrome-plated article with one or more rinses, wherein at least one of these rinses an aqueous solution containing
   1. a. at least one surfactant or at least one mixture of surfactants; and
   2. b. at least one acid or at least one mixture of acids; is and
2. b) electroplating the article in a chromium bath.

The terms mentioned in connection with the kit-of-parts such as objects, chrome plating, rinsing, the galvanic chromium bath, the acids or the mixture of acids and the surfactants or the mixture of surfactants are to be understood analogously to the corresponding terms in the process according to the invention. The embodiments described in the method according to the invention are to be understood analogously for the kit-of-parts.

Examples Experimental group 1

• 260 g/L NiSO₄*6H₂O, 50 g/L NiCl₂ * 6 H₂O, 45 g/L H₃BO₃, 20 mL/L "Glanzträger Ultraglanz 81" (kommerziell erhältlich von Dr. M. Kampschulte GmbH & Co. KG, Düsseldorf), 3 mL/L "Netzmittel Ultraglanz M" (kommerziell erhältlich von Dr. M. Kampschulte GmbH & Co. KG, Düsseldorf), 3 mL/L "Glanzzusatz Premium" (kommerziell erhältlich von Dr. M. Kampschulte GmbH & Co. KG, Düsseldorf), T= 55°C, pH= 4,2 wurden Hullzellbleche 15 Minuten lang bei einer Stromdichte von 4 A/dm² vernickelt. Die Bleche wurden nach dem Vernickeln für kürzeste Zeit (jeweils ca. 1 Sekunde) in zwei aufeinanderfolgende Spülen mit VE-Wasser getaucht und anschließend 30 Sekunden in einer dritten Spüle mit VE-Wasser gespült. Anschließend wurden die Bleche für 30 Sekunden durch vollständige Tauchung in einer erfindungsgemäßen wässrigen Lösung, die mindestens eine Säure oder eine Mischung von Säuren und mindestens ein Tensid oder eine Mischung von Tensiden enthält, Kontaktiert (diese Lösungen werden im folgenden "Fleckenschutzlösungen" oder "FS" bezeichnet). Die verwendeten FS enthielten entweder:
  • Behandlungsmethode 1: 10 g/L Polyethylenglykol alkyl (3-sulfopropyl) diether, Kaliumsalz ( CAS Nummer 119481-71-9 , bezogen von der Firma Raschig GmbH, welche es unter dem Namen "Ralufon F 11-13" vertreibt), 20 mL/L Kieselflußsäure (50%), 0,7 g/L Schwefelsäure (98%), wobei der pH- Wert der Lösung 1,1 betrug;
    oder
  • Behandlungsmethode 2: 7,5 g/L Polyethylen/propylenglycol (beta-naphtyl) (3-sulfopropyl) diether, Kaliumsalz ( CAS Nummer 120478-49-1 , bezogen von der Firma Raschig GmbH, welche es unter dem Namen "Ralufon NAPE 14-90" vertreibt), 3 g/L Schwefelsäure, wobei der pH-Wert der Lösung 1,5 betrug.

In a bright nickel bath of the following composition:

• 260 g / L NiSO ₄ * 6H ₂ O, 50 g / L NiCl ₂ * 6 H ₂ O, 45 g / LH ₃ BO _3, 20 mL / L "gloss carrier Ultra Gloss 81" (commercially available from Dr. M. Kamp Schulte GmbH & Co. KG, Dusseldorf), 3 mL / L "Wetting Agent Ultraglanz M" (commercially available from Dr. M. Kampschulte GmbH & Co. KG, Dusseldorf), 3 mL / L "Glanzzusatz Premium" (commercially available from Dr. M Kampschulte GmbH & Co. KG, Dusseldorf), T = 55 ° C, pH = 4.2, Hullzell plates were nickel-plated for 15 minutes at a current density of 4 A / dm ² . The plates were dipped after nickeling for the shortest time (each about 1 second) in two consecutive rinses with deionized water and then rinsed for 30 seconds in a third rinse with demineralised water. Subsequently, the sheets were contacted for 30 seconds by complete immersion in an aqueous solution according to the invention containing at least one acid or a mixture of acids and at least one surfactant or a mixture of surfactants (these solutions are hereinafter referred to as "stain protection solutions" or "FS"). designated). The FS used contained either:
  • Treatment method 1 : 10 g / L polyethylene glycol alkyl (3-sulfopropyl) diether, potassium salt ( CAS number 119481-71-9 , obtained from the company Raschig GmbH, which sells it under the name "Ralufon F 11-13"), 20 mL / L Kieselflußsäure (50%), 0.7 g / L sulfuric acid (98%), wherein the pH the solution was 1.1;
    or
  • Treatment Method 2: 7.5 g / L polyethylene / propylene glycol (beta-naphthyl) (3-sulfopropyl) diether, potassium salt ( CAS number 120478-49-1 , obtained from the company Raschig GmbH, which sells it under the name "Ralufon NAPE 14-90"), 3 g / L sulfuric acid, wherein the pH of the solution was 1.5.

In a comparative experiment (treatment method 3 ) no contact was made with a FS according to the invention.

In the next step, the nickel-plated, washed with demineralized water and treated with the above-listed invention FS (treatment methods 1 or 2) treated Hullzell sheets or not treated sheet (treatment method 3) were immersed in the 1 liter chromium Hull cell and left there for 30 seconds without power without movement. Then, the current was turned on and the chrome Hullzellbleche for 2 minutes at 7 amps and 40 ° C, wherein the aqueous chromium bath had the following bath composition: 160 g / L CrO _3, 0.4 g / L KF and 0.7 g / L Na ₂ SO ₄ .

The appearance of the sheets after chromium plating is listed in the following table, with the optics evaluated with a scale from 0 to 6. At zero points ("0"), there was no "optically meaningful" chrome plating over the entire metal sheet; at six points ("6"), there was a perfect chrome plating over the entire metal sheet. Table 1: Test Group 1: Overview of the appearance of the sheets after chrome plating treatment optics 1 5 2 5 3 (not according to the invention) 1

As the table shows was under these experimental conditions and if no contact with FS then no meaningful chrome plating of the sheet possible (treatment method 3).

Experimental Group 2:

• 260 g/L NiSO₄*6H₂O, 50 g/L NiCl₂ * 6 H₂O, 45 g/L H₃BO₃, 20 mL/L "Glanzträger Ultraglanz 81" (kommerziell erhältlich von Dr. M. Kampschulte GmbH & Co. KG, Düsseldorf), 3 mL/L "Netzmittel Ultraglanz M" (kommerziell erhältlich von Dr. M. Kampschulte GmbH & Co. KG, Düsseldorf), 3 mL/L "Glanzzusatz Premium" (kommerziell erhältlich von Dr. M. Kampschulte GmbH & Co. KG, Düsseldorf), T= 55°C, pH= 4,2 wurden Hullzellbleche 15 Minuten lang bei einer Stromdichte von 4 A/dm² vernickelt. Die Bleche wurden nach dem Vernickeln für kürzeste Zeit (jeweils ca. 1 Sekunde) in zwei aufeinanderfolgende Spülen mit VE-Wasser getaucht und anschließend 30 Sekunden in einer dritten Spüle mit VE-Wasser gespült. Anschließend wurden die Bleche für eine bestimmte Zeit vollständig (Versuche 2, 4, 5) oder teilweise (Versuche 1 und 3) mit einer FS durch Tauchung kontaktiert.

In a bright nickel bath of the following composition:

• 260 g / L NiSO ₄ * 6H ₂ O, 50 g / L NiCl ₂ * 6 H ₂ O, 45 g / LH ₃ BO _3, 20 mL / L "gloss carrier Ultra Gloss 81" (commercially available from Dr. M. Kamp Schulte GmbH & Co. KG, Dusseldorf), 3 mL / L "Wetting Agent Ultraglanz M" (commercially available from Dr. M. Kampschulte GmbH & Co. KG, Dusseldorf), 3 mL / L "Glanzzusatz Premium" (commercially available from Dr. M Kampschulte GmbH & Co. KG, Dusseldorf), T = 55 ° C, pH = 4.2 Hullzell plates were nickel plated for 15 minutes at a current density of 4 A / dm ² . The plates were dipped after nickeling for the shortest time (each about 1 second) in two consecutive rinses with deionized water and then rinsed for 30 seconds in a third rinse with demineralised water. Subsequently, the sheets were contacted for a certain time completely (tests 2, 4, 5) or partially (tests 1 and 3) with a FS by dipping.

The aqueous stain protection solution used in Experimental Group 2 had the following composition: 3 g / L sulfuric acid and 1.5 g / L "ether sulfate 28% (70%)" (commercially available from Julius Hoesch GmbH & Co. KG, Düren).

One of the sheets was then rinsed once more with deionized water for 30 seconds (experiment 5). In a comparative experiment not according to the invention, no rinsing with FS took place (experiment 6). Thereafter, the panels were immersed in an aqueous chrome bath and left without power for 30 seconds without agitation. The power was then turned on and the panels were chrome plated for 2 minutes at 7 amps and 40 ° C.

Due to the partial immersion of the sheets in experiments 1 and 3, these tests are divided into two parts: on the one hand in an experiment according to the invention (the part of the sheet which was in contact with the FS), on the other hand a test not according to the invention (the part of the sheet which is not was in contact with the FS).

The evaluation of the optics was done with the already mentioned rating scale. Table 2: Test Group 2: Optics of the (part) sheet after treatment with stain protection solution (FS) and subsequent chrome plating. attempt Rinse, duration optics 1a Part of the sheet: 30 seconds with FS 6 1 b (not according to the invention) Part of the sheet: no rinse 1 2 Complete sheet metal: 30 seconds with FS 6 3a Part of the sheet: 10 seconds with FS 5 3b (not according to the invention) Part of the sheet: no rinse 1 4 Complete sheet metal: 10 seconds with FS 5 5 Complete plate: 30 seconds with FS, then 30 seconds with demineralised water 2 6 (not according to the invention) No flushing 1

Experiments 1 and 3 showed that when rinsing a part of the sheet with FS (test 1a and 3a) before chrome plating (the remaining part of the sheets, or experiments 1b and 3b, are here in each case in contact with the air) the part of the sheet which has been treated according to the invention is chrome plated significantly better than the part which is not purged with stain-proofing solution.

Experiments 1 to 4 showed that a rinsing time of 10 seconds with FS (tests 3a and 4) is sufficient to achieve very good results. Experiments 1a and 2 showed, however, that a slightly longer rinsing time of 30 seconds with FS is to be preferred.

When treated with stain protection solution for a further 30 seconds with demineralized water rinse (Run 5), the result was compromised compared to the other attempts of the present invention. This experiment suggests that the contacting of the article with a surfactant and acidic sink according to the invention should preferably take place directly in front of the chromium bath.

The experiments according to the invention all gave better results than those not according to the invention.

Experimental group 3

In a bright nickel bath of the following composition:
260 g / L NiSO ₄ * 6H ₂ O, 50 g / L NiCl ₂ * 6 H ₂ O, 45 g / LH ₃ BO _3, 20 mL / L "gloss carrier Ultra Gloss 81" (commercially available from Dr. M. Kamp Schulte GmbH & Co. KG, Dusseldorf), 3 mL / L "Wetting Agent Ultraglanz M" (commercially available from Dr. M. Kampschulte GmbH & Co. KG, Dusseldorf), 3 mL / L "Glanzzusatz Premium" (commercially available from Dr. M Kampschulte GmbH & Co. KG, Dusseldorf), T = 55 ° C, pH = 4.2, Hullzell plates were nickel-plated for 15 minutes at a current density of 4 A / dm ² . The plates were dipped after nickeling for shortest time (each about 1 second) in two consecutive rinses with deionized water. Subsequently, they were rinsed for 60 seconds in a third aqueous rinse consisting of demineralized water and optionally additives, the additives of this rinse being listed in the following table. Thereafter, the panels were immersed in an aqueous chrome bath and left without power for 30 seconds without agitation. The power was then turned on and the panels were chrome plated for 3 minutes at 7 amps and 40 ° C. The Evaluation of the optics was carried out with the evaluation scale introduced in Experimental Group 1. Table 3: Optics of the sheets after treatment and subsequent chrome plating. attempt Sink, additive optics 1 (not according to the invention) No addition 1 2 (not according to the invention) 1 g / LH ₂ SO ₄ 4 3 (not according to the invention) 3 g / L surfactant Ralufon F 11-13 0 4 3 g / L Surfactant Ralufon F 11-13 + 1 g / LH ₂ SO ₄ " 6

The "surfactant Ralufon F 11-13" mentioned in Table 3 is the already mentioned surfactant marketed by Raschig GmbH.

When chromium plating after washing with water (Experiment 1), a poorly chromed sheet is obtained analogously to the experiments of the prior experimental groups 1 and 2 not according to the invention.

Upon addition of 1 g / L of an acid to the sink (Run 2), compared to Run 1, a significantly better, but still faulty, chrome plating of the sheet is achieved. This improvement in chrome plating by rinsing the article to be chrome plated in an acidic solution has already been addressed in the prior art.

Upon addition of 3 g / L of a surfactant to the sink (Run 3), degradation of the chrome plating is achieved as compared to Run 1. This observation also coincides with the state of the art, in which the presence of surfactants in the rinses in front of the chrome bath is to be avoided.

In Experiment 4 according to the invention, the inventive addition of a surfactant and an acid to the sink was carried out, the concentrations of the two additives being selected analogously to the concentrations of the previous experiments of this experimental group (Experiments 2 and 3 in this experimental group). The chrome plating of the sheet is compared to the experiment in which only acid was added to the sink (Experiment 2), once again improved. Compared to the other two experiments (experiments 1 and 3), the improvement is even more significant.

Claims (15)

Method for producing chromed articles, characterized by the following method steps: a) bringing into contact a chrome-plated article with one or more rinses, wherein at least one of these rinses an aqueous solution containing a. at least one surfactant or at least one mixture of surfactants; and b. at least one acid or at least one mixture of acids; is and b) electroplating the article in a chromium bath. A method according to claim 1, characterized in that on the object to be chromium-plated before the process step a) a bright nickel layer is electrodeposited. Method according to one of claims 1 or 2, characterized in that the total concentration of the surfactants in at least one of the rinses is 0.5 to 50 g / L. A method according to claim 3, characterized in that the pH in at least one of the rinses containing at least the surfactant or at least the mixture of surfactants and at least the acid or at least the mixture of acids is less than 2.0. Method according to one of claims 1 to 4, characterized in that the acids are compatible with the chromium bath. Method according to one of claims 1 to 5, characterized in that the acids are selected from the group consisting of Borflußsäure, Kieselflußsäure, hydrofluoric acid, sulfuric acid, methanesulfonic acid, methanedisulfonic acid and mixtures of said acids. Method according to one of claims 1 to 6, characterized in that the surfactants are anionic surfactants. A method according to claim 7, characterized in that the anionic surfactants are selected from the group consisting of alkyl sulfates, aryl sulfates alkyl sulfonates, aryl sulfonates, alkyl phosphonates, aryl phosphonates, alkyl phosphates, aryl phosphates, alkyl ether sulfates, aryl ether sulfates, alkyl carboxylates, aryl carboxylates, alkyl ether sulfonates, aryl ether sulfonates, their fluorinated and perfluorinated analogs and mixtures thereof. A method according to claim 8, characterized in that the surfactants are selected from the group consisting of octyl sulfate, decyl sulfate, lauryl sulfate, perfluoroheptane sulfate, perfluorohexane sulfate, perfluorooctane sulfate, perfluorodecane sulfate, hexylpoly (oxyethylene) sulfate, octylpoly (oxyethylene) sulfate decylpoly (oxyethylene) sulfate, Polyethylene glycol alkyl (3-sulfopropyl) diether, lauryl ether sulfate and polyethylene / propylene glycol (beta-naphthyl) (3-sulfopropyl) diether. Method according to one of claims 1 to 9, characterized in that the chromium plating in step b) is a bright chrome plating, wherein the layer thickness of the chromium to be deposited is from 0.1 to 2 microns. Method according to one of claims 1 to 10, characterized in that the temperature is at least one of the rinses from 5 to 80 ° C. Method according to one of claims 1 to 11, characterized in that the bringing into contact in step a) is 5 to 900 seconds. Method according to one of claims 1 to 12, characterized in that the aqueous solution in the rinses in relation to the chromium-plated article is stationary or non-stationary and / or that the objects to be chromium-plated are stationary or non-stationary in relation to the aqueous solution. A kit-of-parts for addition to one or more rinses in front of a galvanic chrome bath, the kit-of-parts comprising: iii. an acid or a mixture of acids as the first ingredient, iv. a surfactant or a mixture of surfactants as the second component. Kit of parts according to claim 14 for use in a method of manufacturing chromed articles, characterized by the following method steps: c) bringing into contact an object to be chromed with one or more rinses, wherein at least one of these rinses an aqueous solution containing a. at least one surfactant or at least one mixture of surfactants; and b. at least one acid or at least one mixture of acids; is and d) electroplating the article in a chromium bath.