EP1611269A1

EP1611269A1 - Method for the production of sanitary fittings with a stainless steel finish

Info

Publication number: EP1611269A1
Application number: EP04721193A
Authority: EP
Inventors: Kurt MÜLLMAIER
Original assignee: Blanco GmbH and Co KG
Current assignee: Blanco GmbH and Co KG
Priority date: 2003-03-19
Filing date: 2004-03-17
Publication date: 2006-01-04
Also published as: WO2004083491A1; CA2526077A1; US7854831B2; CA2526077C; WO2004083491A8; US20060060473A1; DE10312308A1

Abstract

The aim of the invention is to provide sanitary fittings, especially water supply fittings which, in terms of aesthetics and haptics, are very similar to the stainless steel surface of stainless steel sinks or are scarcely distinguishable therefrom (stainless steel finish), using starting materials that can be machined at lower cost. According to the invention, a fitting or fitting parts are produced from brass; the fittings or fitting parts are ground and polished; the visible surfaces of the fittings or fitting parts are nickel-plated; the nickel- plated surface of the fittings and fitting parts are ground and/or brushed; and the ground or brushed nickel-plated surfaces of the fittings or fitting parts are chrome-plated.

Description

Process for the production of sanitary fittings with a stainless steel finish

The invention relates to a method for producing a sanitary fitting with a stainless steel finish.

Sanitary fittings, in particular water inlet fittings or sanitary shut-off devices in general, are often used directly together with stainless steel sinks and have the disadvantage that they differ significantly from the material of the stainless steel sink, in particular from the look and feel.

The manufacture of such fittings made of stainless steel is very cost-intensive due to the more complex machining processes involved with stainless steel.

The object of the present invention is to propose sanitary fittings, in particular water inlet fittings and sanitary shut-off devices in general, which come very close in their appearance and feel to the stainless steel surface of stainless steel sinks until they can hardly be distinguished (stainless steel finish) and a process for their production, which is more economical raw materials to be processed are used. The method according to the invention for producing sanitary fittings with a stainless steel finish can be applied to fittings or their parts which are made from brass, zinc die-casting alloys and plastics. Depending on the starting material, there are minor modifications in the preparation of the fittings or their parts for the subsequent common steps of nickel plating and subsequent chrome plating.

In a first variant of the invention, the fittings or their parts are made of brass, and these are first surface-polished. Subsequent (or alternatively) pre-brushing is recommended.

Pre-brushing is particularly recommended for parts with recesses, whereby the recesses in particular should be pre-brushed.

In a second variant of the invention, plastic materials are used.

Plastic materials generally do not need such pretreatment, although they can be coated with a copper layer in the following nickel plating process for better processing.

In a third variant of the invention, the fittings or their parts are made from die-cast zinc alloys.

When using fittings or fittings made of zinc die-casting alloys, copper plating of the surface is first necessary in order to close the surface pores present in zinc die-casting alloy parts (in particular zamak alloy parts) and to obtain a sufficiently smooth surface. After the pretreatment of the parts described above, the further procedure is as follows:

Nickel plating of at least the visible surface of the fitting or the

Valve parts;

Grinding and / or brushing the nickel-plated surfaces of the fitting parts;

Chrome plating of the polished and / or brushed nickel-plated surfaces of the fitting parts.

Surprisingly, applying a typical brush pattern after nickel-plating the surfaces, as is known from stainless steel surfaces, achieves an effect with the subsequent chrome plating that still shines through as a brush pattern. The combination of the metal layers of nickel and chrome can be designed by choosing the appropriate layer thicknesses so that a silver-gray, matt shine is achieved, which essentially corresponds to the silver-gray tint of stainless steel. In particular, a yellow tinge, as is known from nickel-plated surfaces, is avoided and, on the other hand, the blue tint of a conventional chrome-plated surface is also avoided.

When brushing the nickel surface, care is preferably taken to ensure that a surface structure is produced, as is the case with 3M disks of the type SBI-A, diameter 250 mm and a working speed of 600 revolutions per minute is achieved.

The fitting parts are preferably degreased in one or preferably several separate steps prior to nickel plating, further preferably followed by chemical degreasing, ultrasound degreasing and an electrolytic degreasing step.

The nickel bath preferably comprises 60 to 80 grams of nickel metal per liter, which is preferably introduced in the form of nickel chloride and nickel sulfate.

A preferred additive in the electrolytic nickel bath is boric acid, which is preferably added at 30 to 50 grams per liter, particularly preferably 40 grams per liter.

The nickel plating is preferably carried out with a current density of 4 to 5 amperes per square decimeter, lower current densities being used for the nickel plating of brass parts and higher current densities for previously copper-plated zamak or plastic (in particular ABS) parts.

The aforementioned degreasing steps usually take fractions of a minute or just a few minutes. In contrast, the nickel plating step preferably lasts 15 to 25 minutes, depending on the average layer thickness of nickel to be achieved on the component. With the aforementioned specifications, an average nickel layer thickness in the range of 18 to 24 μm is achieved. It has been found that such layer thicknesses are sufficient to withstand a subsequent brushing process, as already described above, and to image a sufficient brush structure. Of course, larger layer thicknesses are possible for the present invention, but this is not brings greater benefits more in the appearance of the parts. In any case, the layer thickness of the nickel layer must be chosen so large that a closed nickel surface remains after the brushing process.

After the nickel plating, the parts are rinsed, finally preferably with demineralized water. The parts are then dried in an oven at a temperature of 60 to 75 ° C.

The nickel plating is followed by chrome plating, which can be carried out in the same way for all parts.

The parts differ from each other in the previously applied IMickle layer, i.e. compared to the electrolytic bath, no longer, so that the following recommendations apply to the processing of brass, zinc die-cast alloys and plastic parts.

Depending on the starting material, it is advisable to carry out a series of degreasing steps, starting with chemical degreasing, ultrasonic degreasing and electrolytic degreasing, before the parts are nickel-plated. This is explained in more detail below.

Even before the chrome plating, degreasing steps must be provided after brushing the nickel-plated surfaces. Here too, a series of degreasing steps, including chemical, ultrasound and electrochemical degreasing, is recommended. The electrolysis bath for the chrome plating preferably contains chromium trioxide in an amount of 300 to 350 grams per liter, smaller amounts of sulfuric acid and a conventional catalyst. The chrome plating process usually takes 3 to 4 minutes and is carried out at a current of preferably 6.5 to 8 amperes per square decimeter at a voltage of 3.2 to 5.6 volts. Under these conditions, an average layer thickness in the range of 0.1 to 0.3 μm is achieved.

This chrome layer thickness is sufficient for many applications. In the case of very heavily used surfaces, especially those that are frequently subjected to cleaning with abrasive cleaning agents or cleaning equipment, significantly thicker chrome layers are recommended, although the brush structure must show through to a sufficient extent.

In the following, the individual nickel-plating and chrome-plating processes will be discussed before the nickel-plating and chrome-plating of brass, zamak and ABS parts are explained in detail using concrete examples.

Nickel plating of brass parts

In a first step, the polished and optionally pre-brushed brass parts are subjected to ultrasonic degreasing at a temperature of 60 to 85 ° C., preferably approx. 75 ° C., in an aqueous medium. The aqueous medium contains a degreasing agent, selected from surfactants, amine saponified fatty acids, weak organic acids and / or glycol ethers, in each case in effective amounts. In a further step, chemical degreasing is carried out one or more times, preferably at temperatures in the range from 40 to 60 ° C. and using an aqueous degreasing medium which contains alkali metal hydroxide as the main constituent and, in addition, further constituents selected from alkali metal silicate, sodium carbonate and phosphates and surfactants. Solubilizers, in particular weak complexing agents, may also be present.

Alkylbenzenesulfonates, ethoxylated fatty alcohols, are used as dispersants or surfactants.

In the case of multiple chemical degreasing processes, the amount of degreasing agent in the medium is preferably reduced, for example halved, with each further degreasing step.

Subsequent to this, cathodic degreasing is preferably carried out, using an aqueous medium in which alkali metal hydroxide is contained as the main constituent of the degreasing agents. In addition, the medium can contain one or more alkali silicates, sodium carbonate, phosphates and surfactants.

In a further degreasing step, which is carried out as anodic degreasing, a medium is used as described above for cathodic degreasing, but preferably with a smaller amount of degreasing agent in the medium. Here, for example, half of the degreasing agent in the medium can be sufficient.

The anodic and cathodic degreasing can also be carried out in the reverse order, with the second electrolytic see degreasing step applies that here is preferably worked with the smaller amount of degreasing agent in the medium.

Finally, rinsing, neutralizing and rinsing are carried out before the nickel plating, the neutralization preferably taking place with sulfuric acid. The rinsing processes are carried out one or more times.

This is followed by the actual nickel plating process with a nickel content in the electrolyte of preferably 60 to 80 grams of nickel content per liter, the nickel content being produced from nickel salts, which are preferably nickel chloride hexahydrate and nickel sulfate hexahydrate. These two salts are particularly preferably used next to one another, particularly preferably in a ratio of approximately 1: 4. As a further component of the electrolyte in nickel plating, boric acid is provided with a content of 30 to 40 grams per liter.

The duration of the nickel-plating process depends, of course, on the desired layer thickness. Usually 15 to 25 minutes are sufficient for nickel plating at a voltage of 6.2 to 8.3 volts and a current density of approx. 4 amperes per square decimeter. The nickel layer formed in this way has an average layer thickness in the range from 18 to 24 μm. This layer thickness is thick enough that a brush structure can be introduced into the surface, the brush structure in terms of its look and feel should correspond to a brush structure which is obtained with grinding wheels of type SBI-A from 3M, diameter 250 mm, if this Grinding wheels are driven at a working speed of 600 revolutions per minute. Vernickelunα of copper-plated zamak and plastic parts

The zamak parts (generally die-cast zinc alloy parts) are first provided with a copper layer in order to smooth the surface, i.e. in order to close pores from the die casting process on the surface and to ensure a smooth surface. Then the copper-plated zamak parts can be treated like the ABS parts, whether they are copper-plated or not.

First of all, chemical degreasing is carried out in an aqueous medium with a degreasing agent, which is predominantly formed by alkali hydroxide, but also comprises larger proportions of sodium carbonate, alkali metal silicates and alkylphenol ethoxylates. In addition, surfactants can also be present in smaller quantities.

Ultrasonic degreasing is then carried out, a degreasing agent being added to the aqueous degreasing medium, which is formed predominantly by sodium borate and sodium carbonate. A mixture of different surfactants is also used.

A cathodic and then anodic degreasing is then carried out as a further degreasing step, in which context the medium essentially contains sodium carbonate as well as sodium metasilicates and smaller amounts of sodium hydroxide as degreasing agent.

Before the actual nickel plating is neutralized again, sulfuric acid is preferably used here and rinsed again with water. The nickel plating process is then carried out, as already described above, although the zamak and ABS parts are preferably operated with a somewhat higher current density. Here, too, nickel layer thicknesses in the range from 18 to 24 μm are achieved in the period from 15 to 25 minutes.

The layer thicknesses achieved in this way are treated as described above, the brushing process then commencing after the oven drying, likewise already described above.

Chrome-plating of the nickel-plated and brushed fitting parts)

This is followed by the actual chrome plating process, which is the same for all sanitary fitting parts, regardless of whether they are based on brass parts, zamak or ABS parts.

First, chemical degreasing is carried out using an aqueous degreasing medium containing degreasing agents, most of which are formed by sodium hydroxide. It also contains significant amounts of sodium carbonate, small amounts of sodium metasilicate, and alkylphenol ethoxylates and surfactants.

An ultrasonic degreasing is then carried out in an aqueous degreasing medium with a degreasing agent which is predominantly formed from sodium borate and smaller amounts of sodium carbonate and various surfactants.

This is followed by rinsing and neutralization with sulfuric acid, followed by rinsing again and then the actual chrome plating. Chromium plating is carried out with a chromium content of 300 to 350 grams per liter of chromium trioxide, small amounts of sulfuric acid and a catalyst consisting of fluorosilicate and sodium chromate.

The period in which the chrome plating is carried out is 3 to 4 minutes and is carried out at a current of 6.5 to 8 amperes per square decimeter at a voltage of 3.2 to 5.6 volts.

During this period and under these conditions, average chromium starch layers are obtained, which are 0.1 to 0.3 μm.

Then it is rinsed with water, finally ultrapure water and then dried in the oven.

The fittings obtained in this way have a surface appearance and haptic that can hardly be distinguished from the stainless steel finish compared to original brushed stainless steel surfaces.

The individual process steps are described in tabular form below as an example. It goes without saying that the degreasing steps in particular can be designed in many different ways and only serve to create the conditions for well-adhering nickel or chrome layers. The nickel-plating and chrome-plating processes themselves also allow for a wide variety of variations, the results of the layer thicknesses described above having to be achieved primarily. Nickel plating of brass parts:

Nickel-plating of copper-plated zamak and ABS parts:

Chrome plating of brass, zamak and ABS parts

Explanations of the abbreviations used in the tables:

(A) Mixture of surfactants, aminically saponified fatty acids, weak organic acids, glycol ethers

(B) Mixture containing sodium hydroxide as the main constituent and also sodium metasilicate, sodium carbonate, solubilizers in the form of weak complexing agents, phosphates, alkylbenzenesulfonates and fatty alcohols

(C) Mixture containing as main components sodium hydroxide, sodium metasilicate and sodium carbonate and in addition complexing agents, phosphates and surfactants

(D) Mixtures containing sodium hydroxide as the main constituent, in addition sodium carbonate, sodium silicate, alkylphenol ethoxylate, surfactants

(E) Mixtures contain sodium borate as the main constituent and, in addition, sodium carbonate, surfactants

(F) Mixtures of the main components sodium carbonate, sodium metasilicate, sodium hydroxide

Fluorosilicate catalyst in combination with sodium chromate

Claims

Patent claims

1. Process for the production of sanitary fittings with stainless steel finish, characterized by the steps

Manufacture of a fitting or fitting parts made of brass; Grinding and polishing the fittings or fitting parts; Nickel plating of the visible surfaces of the fittings or fitting parts;

Grinding and / or brushing the nickel-plated surface of the fittings and fitting parts;

Chrome-plating the polished or brushed nickel-plated surfaces of the fittings or fitting parts.

2. Process for the production of sanitary fittings with a stainless steel finish, characterized by the steps

Manufacture of a valve or parts thereof from a plastic, in particular ABS;

Nickel plating of the visible surfaces of the fittings or fitting parts;

Grinding and / or brushing the nickel-plated surfaces of the fittings or fitting parts;

Chrome-plating the polished and / or brushed nickel-plated surface of the fittings or fitting parts.

3. Process for producing a sanitary fitting with a stainless steel finish, characterized by the steps

Manufacture of a fitting or parts thereof from a die-cast zinc alloy, in particular zamak;

Copper-plating the visible surface of the fittings or fitting parts;

Nickel plating of the visible surfaces of the fittings or fitting parts;

Grinding and / or brushing the nickel-plated surface of the fittings or fitting parts;

Chrome-plating the polished and / or brushed nickel-plated surface of the fitting parts.

4. The method according to any one of claims 1 to 3, characterized in that the fitting parts are subjected to degreasing one or more times before nickel plating, chemical, electrochemical and / or ultrasonic degreasing being used.

5. The method according to claim 4, characterized in that the degreasing takes place at elevated temperatures in an aqueous medium.

6. The method according to claim 4 or 5, characterized in that the fitting parts are degreased both anodically and cathodically.

7. The method according to any one of the preceding claims, characterized in that the electrolytic bath in the nickel plating contains metallic nickel in an amount of 60 to 80 grams per liter, preferably about 70 grams per liter.

8. The method according to claim 7, characterized in that the metallic nickel is formed in the electrolytic nickel solution of nickel chloride and / or nickel sulfate.

9. The method according to claim 8, characterized in that the metallic nickel of nickel chloride and nickel sulfate, in particular in the ratio of nickel chloride to nickel sulfate of about 1: 4 is formed.

10. The method according to any one of the preceding claims, characterized in that the nickel bath comprises boric acid, in particular in an amount of 30 to 50 grams per liter.

11. The method according to any one of the preceding claims, characterized in that the nickel layer is applied to the fittings or fitting parts with a thickness of on average 18 to 24 microns.

12. The method according to any one of the preceding claims, characterized in that a chemical degreasing, an ultrasonic degreasing and / or an electrolytic degreasing is carried out before the chrome plating, wherein individual degreasing steps can be repeated several times.

13. The method according to claim 12, characterized in that the electrolytic degreasing is a cathodic degreasing.

14. The method according to any one of the preceding claims, characterized in that the chrome plating is carried out in a chrome bath which contains 300 to 350 grams of chromium trioxide.

15. The method according to any one of the preceding claims, characterized in that the brushing is carried out before the chrome plating in such a way that a brushing pattern is obtained which is that of grinding wheels of the type SBI-A from 3M with a diameter of 250 mm and a Working speed of 600 revolutions per minute corresponds.

16. Sanitary fitting or parts thereof, produced by a method according to one of claims 1 to 15.