JP2023553966A - black plated board - Google Patents

Abstract

The invention relates to a black plated substrate comprising a base substrate and a layer stack deposited thereon, the layer stack comprising a black chrome plating layer on its surface comprising a conversion layer having a depth of 30 nm or more. The present invention relates to a black-plated substrate, characterized in that the conversion layer does not contain metallic chromium or only contains at most 2 at % of metallic chromium, based on the total number of elemental chromium and chromium atoms in the conversion layer.

Description

The invention relates to a black plated substrate comprising a base substrate and a layer stack deposited thereon, the layer stack comprising a black chrome plating layer on its surface comprising a conversion layer having a depth of 30 nm or more. The present invention relates to a black-plated substrate, characterized in that the conversion layer does not contain metallic chromium or only contains at most 2 at % of metallic chromium, based on the total number of elemental chromium and chromium atoms in the conversion layer.

Interest in dark chromium layers has been observed since the earliest days of chromium layers. Starting with the dark hexavalent chromium layer, there is now a major shift in focus to the trivalent chromium layer for higher environmental acceptability.

Typically, each chrome layer, especially a dark chrome layer, is characterized by a color value relative to the L ^* a ^* b ^* color space system. The a ^* and b ^* values define the color of the respective chrome layer, while the L ^* value defines the whiteness (also called lightness). An L ^* value of 100 defines diffuse white, and an L ^* value of 0 is deep black. The values of a ^* and b ^* can be positive and negative, where the a ^* values represent the colors green (negative) and red (positive), and the b ^* values represent the colors blue (negative) and yellow (positive). represents. When the combination of a ^* and b ^* is 0, it represents an achromatic gray, and the lower the L ^* value (for example, 50 or less), the darker the achromatic black becomes.

Depending on the chemical composition of the respective aqueous trivalent chromium electrolytic bath and/or its deposition parameters, a wide variety of L ^* a ^* b ^* values can be generated.

Analysis has shown that such deep achromatic black colors are often accompanied by certain surface modifications, especially on the outer surface of individual electrolytic black chromium plating layers (sometimes referred to as conversion layers or surface modification layers). It is shown.

US Patent Application Publication No. 2020/094526 (A1) refers to black plated resin parts and methods of manufacturing the same. This document discloses a black chromium plating layer containing such a surface modification layer. US '526 teaches that the thickness of the surface-modified layer is correlated with the amount of agent M added (see US '526, [0078]) and the applied current density (see [0079]). Disclosed. Furthermore, US '526 discloses a surface modification layer thickness of up to 37.7 nm (see sample no. 1).

Our study showed that the long-term stability of black color is better preserved with thicker metamorphosed layers. It is thought that the wear resistance of the chemical conversion layer improves as the thickness of the chemical conversion layer increases. This means that if the layer thickness has at least a sufficient minimum thickness, the black color will last longer and be protected from physical contact, for example. Furthermore, it is also assumed that as the thickness of the conversion layer increases, the hardness of this layer increases.

Therefore, there is a continuing need to provide improved black plated substrates.

U.S. Patent Application Publication No. 2020/094526 (A1)

It is therefore an object of the present invention to provide a black plated substrate, which in particular provides a black chrome plated layer comprising a conversion layer with improved color stability and wear resistance, so that the optical impression is maintained for a longer time. It is to provide.

These objects meet the present invention, namely a black plated substrate comprising a base substrate and a layer stack deposited thereon, the layer stack comprising:
(a) one or more intermediate plating layers formed on a base substrate;
(b) a black chromium plating layer formed on one or more intermediate plating layers;
including;
- The black chrome plating layer is
- The L ^* value is 55 or less according to the L ^* a ^* b color system;
- Contains the elements chromium, carbon and oxygen;
- contains on its surface a chemical conversion layer with a depth of 30 nm or more, measured from the surface towards one or more intermediate plating layers;
- The total thickness including the chemical conversion layer is 100 nm or more; in a black plated substrate,
The conversion layer is characterized in that it does not contain metallic chromium or only contains at most 2 at % of metallic chromium, based on the total number of elemental chromium and chromium atoms in the conversion layer,
Solved by black plated substrate.

In the context of the present invention, the emphasis is on decorative applications. Therefore, in the context of the present invention, a black plated substrate and therefore a black chrome plated layer preferably refers to a decorative black plated substrate and a decorative black chrome plated layer, respectively. Therefore, the black chromium plating layer is preferably not a hard black chromium plating layer.

Our experiments show that in each electrolytic bath utilized in each plating method, not only is the correct plating additive used, but also that if a specific amount (see example below) is used, the thickness It was shown that a chemical stratification layer with an increased value can be obtained. Furthermore, in such a desired black chromium plating layer, the amount of metallic chromium in the conversion layer is likely to be particularly low, ie, not exceeding 2 at%. As a result, a relatively increased (desired) thickness of the conversion layer is obtained, which increases the abrasion resistance and the abrasion resistance, respectively. The result is a black plated substrate with improved lifetime in terms of optical black perception.

The black substrate includes a black chrome plated layer obtained from a plating process, preferably an electrolytic plating process. This process involves a black chrome plating layer being obtained by a wet chemical plating process. In other words, the black-plated substrate and the black chrome-plated layer are not obtained by physical deposition methods, such as vapor deposition, respectively.

The present invention specifically refers to such specially designed black plated substrates having individual black chrome plated layers including conversion layers as defined above and throughout the text.

The black plated substrate of the present invention includes a base substrate.

Preferably, the base substrate comprises a metal or non-metal base substrate, preferably a non-metal base substrate, most preferably a plastic base substrate, preferably a metal or non-metal base substrate, preferably a non-metal base substrate, most preferably This is a black plated substrate of the present invention which is a plastic base substrate.

Preferred is the black plated substrate of the present invention, wherein the metal base substrate is an iron-containing metal base substrate, preferably an iron-based substrate, most preferably a cast iron-based substrate. Preferably, the iron-containing metal base substrate includes a brass base substrate and/or a zinc-based die cast base substrate.

Preferably, the non-metallic base substrate, preferably a plastic base substrate, is made of acrylonitrile-butadiene-styrene (ABS), acrylonitrile-butadiene-styrene-polycarbonate (ABS-PC), polypropylene (PP), polyamide (PA), polyurethane ( PU), polyepoxide (PE), polyacrylate, polyetherimide (PEI), polyetherketone (PEK), mixtures thereof, and/or composites thereof; preferably acrylonitrile-butadiene-styrene (ABS), acrylonitrile - The black plated substrate of the present invention, comprising butadiene styrene-polycarbonate (ABS-PC), polyamide (PA), polyurethane (PU), polyepoxide (PE), polyacrylate, mixtures thereof, and/or composites thereof It is. Such plastic-based substrates are typically used for decorative applications such as automotive parts, especially ABS and ABS-PC.

The black plated substrate of the present invention further includes a layer stack deposited on the base substrate. The layer stack is
(a) includes one or more intermediate plating layers formed on a base substrate.

Preferred is the black plated substrate of the present invention, in which the one or more intermediate plated layers include one or more selected from the group consisting of a nickel layer, a nickel alloy layer, a copper layer, and a copper alloy layer. Preferably they are sequential, forming a series of intermediate plating layers, and are adjacent.

More preferably, the layer stack comprises two or more intermediate plated layers, most preferably at least one intermediate layer comprising copper and/or copper alloys and further comprising at least one intermediate layer comprising nickel and/or nickel alloys. layer.

Preference is therefore given to layer stacks comprising one or more intermediate plating layers following one another in sequence.

In the context of the present invention, the term "plating" refers to deposition with and without the aid of an external electrical source. Therefore, it preferably includes not only electroplating, but also electroless plating, for example with the aid of reducing agents.

Preferably, the one or more intermediate plating layers formed on the base substrate include at least one microporous nickel plating layer (sometimes referred to as MPS nickel plating layer). be. Preferably, such a layer comprises electrically non-conductive microparticles. This condition most preferably applies when the base substrate is a non-metallic base substrate, preferably a plastic base substrate. Preferably, this intermediate plating layer, if present, is adjacent to the black chrome plating layer.

Preferred are black plated substrates of the present invention in which the one or more intermediate plated layers formed on the base substrate include at least one bright nickel plated layer or at least one satin nickel plated layer. This condition most preferably applies when the base substrate is a non-metallic base substrate, preferably a plastic base substrate.

Preferred are black plated substrates of the present invention in which the one or more intermediate plating layers formed on the base substrate include at least one semi-bright nickel plating layer. This condition most preferably applies when the base substrate is a non-metallic base substrate, preferably a plastic base substrate. More preferred is the black plated substrate of the present invention, in which the semi-bright nickel plating layer is present in addition to the bright nickel plating layer or the satin nickel plating layer.

Preferably, the one or more intermediate plating layers formed on the base substrate include at least one nickel alloy plating layer, preferably adjacent to (i.e. in direct contact with) the base substrate. It is a board. This condition most preferably applies when the base substrate is a non-metallic base substrate, preferably a plastic base substrate.

Preferably, the one or more intermediate plating layers formed on the base substrate include at least one copper plating layer, preferably adjacent to (i.e. in direct contact with) the aforementioned at least one nickel alloy plating layer. ), which is a black plated substrate of the present invention. This condition most preferably applies when the base substrate is a non-metallic base substrate, preferably a plastic base substrate.

It is highly preferred that
- a non-metallic based substrate, preferably a plastic based substrate, most preferably a plastic based substrate as mentioned above as preferred;
- a layer stack deposited on said non-metallic base substrate (or on said preferred base substrate specified as preferred), starting from said non-metallic base substrate, comprising:
- optionally with a nickel or nickel alloy plating layer, preferably an electroless nickel alloy plating layer;
- a copper plating layer, preferably an electrolytic copper plating layer;
- optionally with a semi-bright nickel plating layer;
- with a bright nickel plating layer or a satin nickel layer;
- optionally with a microporous nickel plating layer;
- a black chrome plating layer as defined throughout the invention;
- a black plated substrate of the invention, comprising a layer stack, optionally sequentially comprising a passivation layer and/or an anti-fingerprint layer.

Preferably, the features and preferred features relating to the individual layers mentioned apply equally to the individual layers in this highly preferred black plated substrate of the invention. Furthermore, additional layers in the layer stack, for example an activation layer containing palladium, are not excluded and may also be one of the one or more intermediate plated layers.

Preferably, the black chrome plating layer (including conversion layer) or the passivation layer (if present and deposited over the black chrome plating layer) is the outermost layer of the layer stack.

Preferably, the optional passivation layer comprises trivalent chromium phosphate and/or (preferably or) manganese species. Most preferably, the optional passivation layer does not significantly affect the optical appearance of the black chrome plated layer, particularly with respect to the L ^* , a ^* , and b ^* values of the black chrome plated layer.

The layer stack further includes a black chrome plating layer formed on the one or more intermediate plating layers. Generally, black plated substrates of the present invention are preferred, where the black chrome plated layer is adjacent to the outermost intermediate plated layer. The black chromium plating layer is preferably an electrolytic black chromium plating layer.

In the context of the present invention, the chrome plating layer is black. This black color is preferably optically perceived as a deep, dark black. Most preferably, the entire black plated substrate is perceived this way.

Most preferred are the black plated substrates of the present invention, in which the black chromium plated layer is obtained from a trivalent chromium electrolytic bath. This means that the source of chromium in the black chromium plating layer is chromium in the trivalent state and not from hexavalent chromium.

Preferably, the black chromium plating layer is 53 or less, preferably 51 or less, more preferably 50 or less, even more preferably 49 or less, even more preferably 47 or less, most preferably 45 or less, and even more preferably The black plated substrate of the present invention has an L ^* value of 43 or less. This condition is most preferably applied equally to the entire black plated substrate.

More preferably, the L ^* value of the black chrome plating layer is 30 to 55, preferably 32 to 53, more preferably 34 to 51, even more preferably 36 to 49, most preferably 38 to 47, even more preferably The black plated substrate of the present invention is in the range of 40 to 45. This condition most preferably applies equally to the entire black plated substrate.

More preferred is an optical perception of deep, dark black with reduced or no optical perception of other colors such as yellowish, brownish, bluish, etc. This means that the optical perception of a deep dark black is most preferably a saturated dark black optical perception.

Therefore, it is preferable that the black chrome plating layer has a b* value of +7 or less, +6 or less, more preferably +5 or less, even more preferably +4 or less, and most preferably +3 or less according ^to the L ^* a ^* b color system. It is a black plated substrate of the present invention having: This condition most preferably applies equally to the entire black plated substrate.

More preferably, the b ^* value of the black chromium plating layer is -6 to +6, preferably -5 to +5, more preferably -4 to +4, even more preferably -3 to +3, and most preferably -2 to +4. +2, more preferably in the range of -1 to +1, the black plated substrate of the present invention. This condition most preferably applies equally to the entire black plated substrate.

Preferably, the black chrome plating layer has an a* value of +5 or less, +4 or less, more preferably +3 or less, even more preferably +2 or less, and most preferably +1 or less according to the L ^* a ^{* b} color system. , a black plated substrate of the present invention. This condition most preferably applies equally to the entire black plated substrate.

More preferably, the a ^* value of the black chrome plating layer is -5 to +5, preferably -4 to +4, more preferably -3 to +3, most preferably -2 to +2, and even more preferably -1 to +3. The black plated substrate of the present invention has a range of +1. This condition most preferably applies equally to the entire black plated substrate.

The black chrome plating layer typically contains chromium and is preferably in a predominantly metallic state.

Therefore, it is preferable that the black chromium plating layer contains 20 at% to 70 at%, preferably 25 at% to 63 at%, more preferably 29 at% to 56 at%, based on the total amount of atoms in the black chromium plating layer including the chemical conversion layer. %, even more preferably from 33 at% to 51 at%, most preferably from 35 at% to 47 at%, even most preferably from 38 at% to 43 at%.

As mentioned above, the source of chromium in the black chromium plating layer is preferably chromium in the trivalent state. This operation typically involves utilizing complexing agents in individual electrolytic baths to complex individual trivalent chromium ions. Typically, in contrast to a hexavalent chromium source, the above operations provide a constant carbon content in the black chromium plating layer compared to a chromium plating layer derived from a hexavalent chromium source.

Therefore, it is preferable that the black chromium plating layer contains 5 at% to 40 at%, preferably 6 at% to 33 at%, more preferably 7 at% to 28 at%, based on the total amount of atoms in the black chromium plating layer including the chemical conversion layer. %, even more preferably from 8 at% to 24 at%, most preferably from 9 at% to 20 at%, even most preferably from 10 at% to 16 at%.

Preferably, the black chromium plating layer is 12 at% to 40 at%, preferably 14 at% to 38 at%, more preferably 16 at% to 36 at%, based on the total amount of atoms in the black chromium plating layer including the chemical conversion layer. Even more preferably the black plated substrate of the present invention comprises a total amount of oxygen in the range of 18 at% to 34 at%, most preferably 20 at% to 31 at%, even most preferably 22 at% to 28 at%.

To obtain a black plated substrate, particularly a black chrome plated layer, preferably a blackening agent is typically utilized in the respective electrolytic bath for depositing the black chrome plated layer. In some cases organic and/or inorganic blackening agents are preferred. Highly preferred inorganic blackening agents are iron-containing compounds, preferably iron ions, most preferably iron(II) ions, cobalt-containing compounds, preferably cobalt ions, most preferably cobalt(II) ions, thiocyanate, and/or or their salts. Preferred organic blackening compounds include methionine and/or its salts. Preferably, an inorganic blackening agent, most preferably said iron-containing compound and cobalt-containing compound, is incorporated into the black chrome plating layer.

Preferably, the black chromium plating layer preferably has a content of 5 at% to 23 at%, preferably 6 at% to 21 at%, more preferably 7 at% to The black plated substrate of the present invention comprises a total amount of iron in the range of 19 at%, even more preferably 8 at% to 17 at%, most preferably 9 at% to 15 at%, even most preferably 10 at% to 13 at%.

Preferably, alternatively or additionally (preferably alternatively) to the iron, the black chromium plating layer preferably comprises, based on the total amount of atoms in the black chromium plating layer including the conversion layer, 5 at% to 23 at%, preferably 6 at% to 21 at%, more preferably 7 at% to 19 at%, even more preferably 8 at% to 17 at%, most preferably 9 at% to 15 at%, even most preferably 10 at% to 13 at%. The black plated substrate of the present invention comprises cobalt in a total amount in the range of %.

Organic blackening agents are typically incorporated into the black chromium plating layer via sulfur atoms. Therefore, it is preferable that the black chromium plating layer is preferably 0.1 at% to 10 at%, preferably 0.3 at% to 9 at%, based on the total amount of atoms in the black chromium plating layer including the chemical conversion layer. More preferably a total amount of sulfur ranging from 0.5 at% to 8 at%, even more preferably from 0.7 at% to 7 at%, most preferably from 1 at% to 6 at%, even most preferably from 1.3 at% to 5 at%. The black plated substrate of the present invention includes:

Preferably, the black chromium plating layer is preferably from 0.1 at% to 10 at%, preferably from 0.5 at% to 9 at%, more preferably from 0.5 at% to 9 at%, based on the total amount of atoms in the black chromium plating layer including the chemical conversion layer. contains a total amount of nitrogen ranging from 1 at% to 8 at%, even more preferably from 1.5 at% to 7 at%, most preferably from 2 at% to 6 at%, even most preferably from 2.5 at% to 5 at%. This is a black plated board.

The black chrome plating layer includes a chemical conversion layer on its surface. In the context of the present invention, the conversion layer has a depth (or thickness) of at least 30 nm. This depth (or thickness) is the minimum depth (or thickness) useful to achieve the minimum desired abrasion and abrasion resistance, respectively, to maintain a relatively long optical life of the black plated substrate. or thickness).

Preferably, the chemical conversion layer has a thickness of at least 32 nm, preferably at least 35 nm, more preferably at least 38 nm, even more preferably at least 41 nm, even more preferably at least 44 nm, most preferably at least 48 nm, even more preferably at least 51 nm. 1 is a black plated substrate of the present invention having a depth.

Preferably, the conversion layer has a maximum depth of 90 nm or less, preferably 80 nm or less, more preferably 70 nm or less, even more preferably 66 nm or less, and even more preferably 62 nm or less, most preferably 60 nm or less. This is a black plated substrate of the invention.

More preferably, the chemical layer has a thickness of 30nm to 90nm, preferably 32nm to 85nm, more preferably 35nm to 80nm, even more preferably 38nm to 70nm, and even more preferably 41nm to 66nm, most preferably 44nm to 62nm, More preferably, the black plated substrate of the present invention has a depth in the range of 48 nm to 60 nm.

In the black plated substrate, the black chromium plating layer excluding the chemical conversion layer preferably has a thickness higher than the depth (or thickness) of the chemical conversion layer. Preferably, the black chrome plating layer excluding the conversion layer is at least twice the thickness of the conversion layer, preferably at least 3 times, more preferably at least 4 to 5 times, even more preferably at least 6 to 7 times, most preferably is at least 8-9 times, more preferably at least 10 times.

Preferably, the depth or thickness of the conversion layer is B. R. Strohmeier, Surface and Interface Analysis, Vol. 15, pp. 51-56, (1990).

Preferably, the black chromium plating layer has a thickness of 130 nm or more, preferably 160 nm or more, more preferably 190 nm or more, even more preferably 220 nm or more, even more preferably 250 nm or more, most preferably 275 nm or more, and even more preferably The black plated substrate of the present invention has a total thickness including the chemical conversion layer of 300 nm or more.

More preferably, the black chromium plating layer has a thickness of 100 nm to 1000 nm, preferably 130 nm to 900 nm, more preferably 160 nm to 800 nm, even more preferably 190 nm to 700 nm, and even more preferably 220 nm to 600 nm, most preferably 250 nm to The black plated substrate of the present invention has a total thickness of 500 nm, more preferably in the range of 275 nm to 400 nm. Such total thickness typically lasts well over the typical lifespan of an individual black plated substrate, even if the respective black plated substrate is regularly touched and/or occasionally cleaned by wiping. Achieve color stability.

Furthermore, in the context of the present invention, it is desired to contain no or only small amounts of metallic chromium in the conversion layer. The depth of the conversion layer has been shown to be correlated with the amount of metallic chromium in the conversion layer, and decreasing the amount of metallic chromium appears to increase the depth. Without wishing to be bound by theory, it is believed that this is a result of the combination of specific blackening agents in specific amounts (see Examples).

Preferably, the conversion layer is free of metallic chromium or contains only up to 1.7 at% metallic chromium, based on the total number of elemental chromium and chromium atoms in the conversion layer; or contains at most 1.5 at% chromium metal; more preferably no chromium metal or at most 1.2 at% chromium metal; even more preferably , contains no metallic chromium or contains only up to 1 at % metallic chromium, and even more preferably contains no metallic chromium or contains only up to 0.8 at % metallic chromium, most preferably Preferably, it is free of metallic chromium or contains only up to 0.5 at% metallic chromium, and most preferably it is free of metallic chromium or contains only up to 0.3 at% metallic chromium. This is the black plated substrate of the present invention.

Besides a minimal amount of metallic chromium (or no metallic chromium), the conversion layer also contains chromium hydroxide and chromium oxide. Most preferably, chromium is present only in the form of metallic chromium, chromium hydroxide and chromium oxide up to a maximum of 2 at% (including 0 at%). Therefore, more preferably, the conversion layer is composed of the above-described chromium based on the chromium species in the conversion layer.

Preferably, the conversion layer preferably contains from 40 at% to 75 at%, preferably from 46 at% to 70 at%, more preferably from 50 at% to 66 at%, most preferably from 40 at% to 75 at%, based on the total number of elemental chromium and chromium atoms in the conversion layer. The black plated substrate of the present invention preferably comprises chromium in the form of chromium hydroxide in a total amount ranging from 54 at% to 62 at%.

Preferably, the conversion layer preferably contains from 25 at% to 55 at%, preferably from 29 at% to 51 at%, more preferably from 32 at% to 48 at%, most preferably from 32 at% to 48 at%, based on the total number of elemental chromium and chromium atoms in the conversion layer. The black plated substrate of the present invention preferably comprises chromium in the form of chromium oxide in a total amount in the range of 35 at% to 45 at%.

More preferably, the conversion layer includes chromium oxide and chromium hydroxide, with the total amount of chromium hydroxide being greater than the chromium oxide. This point has also been shown by independent experiments to be a highly desirable feature of the black plated substrate according to the invention (see Examples below).

Preferably, in the chemical conversion layer, the atomic ratio of elemental chromium to elemental oxygen is less than 1, and/or preferably and in the black chromium plating layer, which does not include a chemical conversion layer, the atomic ratio of elemental chromium to elemental oxygen is less than 1. The black plated substrate of the present invention is larger than 1.

In some cases, black plated substrates of the present invention are preferred, in which the black chrome plated layer comprises particles, preferably nanoparticles. Preferred particles contain one or more chemical elements selected from the group consisting of silicon, aluminum and carbon, preferably silicon and aluminum, most preferably aluminum.

Preferably the particles have a particle size of less than 1000 nm, preferably less than 500 nm, more preferably at least 90% of the particles have a particle size of less than 500 nm, most preferably at least 90% of the particles have a particle size of less than 150 nm. with a particle size less than or equal to

Preferably, the particles are 100 nm or less, preferably 80 nm or less, more preferably 60 nm or less, even more preferably 50 nm or less, most preferably 40 nm or less, very most preferably 30 nm or less, even most preferably 25 nm or less on a volume basis. It has an average particle size D ₅₀ of .

Most preferably the particles include aluminum oxide, preferably aluminum oxide particles.

Preferred is the black plated substrate of the present invention in which the black chromium plated layer does not substantially contain zinc, preferably does not contain zinc. More preferably, the entire layer stack is substantially free of zinc, preferably free of zinc.

Preferred is the black plated substrate of the present invention in which the black chromium plated layer does not substantially contain fluorine, preferably does not contain fluorine. More preferably, the entire layer stack is substantially free of fluorine, preferably free of fluorine.

Preferred is the black plated substrate of the present invention in which the black chromium plated layer does not substantially contain, preferably does not contain aluminum. More preferably, the entire layer stack is substantially free, preferably free of aluminum.

The spirit of the invention is further illustrated in the following examples, without limiting the scope of the invention, which is defined in the claims herein.

As a substrate, an ABS plaque was used, which was pretreated as follows before the deposition of the black chrome plating layer:

In the first step, the ABS plaques were washed with Uniclean® 151 (a product of Atotech) for 5 minutes at 50°C.

In the second step, the cleaned substrate was subjected to chromium-sulfuric acid etching at about 70° C. for about 10 minutes. In a subsequent step, the etched substrate was activated with the help of colloidal palladium.

In the third step, the activated substrate was subjected to an electroless nickel plating step (10 minutes, 40° C.), followed by a 10 volume % sulfuric acid immersion step and an electroless copper plating step.

In the fourth step, the copper-plated substrate was further subjected to an electrolytic copper plating step (25° C., 50 minutes, 4 A/dm ² ).

In the fifth step, the electrolytic copper plated substrate is subjected to a semi-bright nickel plating process (55°C, 15 minutes, 4A/dm ² ), followed by a bright nickel plating process (55°C, 25 minutes, 4A/dm ² ). provided.

In the sixth step, the bright nickel-plated substrate was subjected to a microporous nickel layer plating step (55° C., 4 minutes, 3 A/dm ² ).

In the seventh step, the following aqueous (i.e., the only solvent was water) trivalent chromium electrolytic bath was used to immerse the black chromium plating layer:
approximately 20 g/L to 25 g/L Cr ³⁺ ions (provided as basic chromium sulfate);
Formic acid of about 30g/L to 45g/L,
Approximately 60g/L boric acid,
Tbl1 potassium thiocyanate,
methionine of Tbl1,
about 10 g/L ammonium bromide,
about 100 g/L ammonium chloride,
About 100 g/L potassium chloride and about 0.5 g/L FeSO _4.7 H ₂ O.

The electrolytic bath further contained small amounts (up to 4 g/L) of saccharin and 5 g/L to 50 g/L of S-containing diol.

The pH value was adjusted to 3.2.

In subsequent steps, electroplating was performed for about 3 minutes to obtain a current density of about 10 A/dm ² . The temperature of each electrolytic bath was approximately 35°C. Stirring was performed by air stirring. As a result, a uniformly distributed black chromium plating layer was deposited.

Additionally, the substrate plated with the black chrome plating layer was subjected to a passivating composition containing permanganate.

In the eighth step, the substrate was immersed in hot water (80° C.) for 10 minutes in a rinsing step. This applied to Examples E and CE1; in Example CE2 no such immersion was performed.

Thereafter, the L ^* a ^* b ^* value according to the L ^* a ^* b ^* color space system was determined (Konica Minolta CM-700 D spectrophotometer; CIE standard illuminator D65 and 10° standard observer). Calibration of the spectrophotometer was performed using black and white standards.

Furthermore, HAXPES measurements were carried out at the BESSY synchrotron (Berlin) (photon energy: 6000 eV; analyzer: EW4000 manufactured by ScientaOmicron; peak resolution was determined by U.S. Patent Application Publication No. 2020/094526 (A1), [0070] (as outlined in ). The results are summarized in Table 1 below.

In Table 1, "E" indicates an example according to the present invention, and "CE" indicates a comparative example.

Table 1 shows that as the total content of methionine and potassium thiocyanate decreases (from 435 mmol/L for E to 251 mmol/L for CE2), the layer thickness of the conversion layer correspondingly decreases (from 55 nm for E to 251 mmol/L for CE2). CE2 to 25 nm).

In contrast, as the relative amount of chromium metal increases, the layer thickness of the conversion layer decreases.

Comparative Example CE2 did not undergo immersion in 80° C. hot water, which was done in Comparative Example CE1. As can be seen from Table 1, the total amount of methionine and potassium thiocyanate seems to have a large effect on the thickness of the conversion layer.

Furthermore, only Example E according to the invention shows a higher relative total amount of chromium hydroxide than chromium oxide.

As a result, the above examples show that a particularly high conversion layer thickness correlates with a significantly lower chromium metal content in the conversion layer.

In further tests, the black chrome plating layer of Example E that was subjected to intensive cleaning was protected longer against unwanted abrasion and therefore had a darker color than in the case of the black chrome plating layers of Comparative Examples CE1 and CE2. The stability was good. It has been observed that when the conversion layer is at least substantially removed from the black chrome plating layer, a brighter black appears below the conversion layer.

Claims (15)

A black plated substrate comprising a base substrate and a layer stack deposited thereon, the layer stack comprising:
(a) one or more intermediate plating layers formed on a base substrate;
(b) a black chrome plating layer formed on one or more intermediate plating layers;
including;
The black chrome plating layer is
According to the L ^* a ^* b color system, the L ^* value is 55 or less;
Contains the elements chromium, carbon, and oxygen;
The surface includes a chemical conversion layer with a depth of 30 nm or more measured from the surface toward one or more intermediate plating layers;
The total thickness including the chemical conversion layer is 100 nm or more;
On black plated substrate,
The conversion layer is characterized in that it does not contain metallic chromium or only contains at most 2 at % of metallic chromium, based on the total number of elemental chromium and chromium atoms in the conversion layer,
Black plated board. A black plated substrate according to claim 1, wherein the base substrate is a metal or non-metal base substrate, preferably a non-metal base substrate, most preferably a plastic base substrate. The black plated substrate according to claim 1 or 2, wherein the one or more intermediate plated layers include one or more selected from the group consisting of a nickel layer, a nickel alloy layer, a copper layer, and a copper alloy layer. The black chromium plating layer has an L of 53 or less, preferably 51 or less, more preferably 50 or less, even more preferably 49 or less, even more preferably 47 or less, most preferably 45 or less, and even more preferably 43 or less. The black plated substrate according to any one of claims 1 to 3, which has a value of ^* . Claim 1, wherein the black chrome plating layer has a b* value ^of +7 or less, +6 or less, more preferably +5 or less, even more preferably +4 or less, and most preferably +3 or less according to the L ^* a ^* b color system. 4. The black plated substrate according to any one of 4 to 4. The black chromium plating layer is 20 at% to 70 at%, preferably 25 at% to 63 at%, more preferably 29 at% to 56 at%, even more preferably, based on the total amount of atoms in the black chromium plating layer including the chemical conversion layer. A black plated substrate according to any one of claims 1 to 5, comprising a total amount of chromium in the range 33 at% to 51 at%, most preferably 35 at% to 47 at%, even most preferably 38 at% to 43 at%. The black chromium plating layer is 5 at% to 40 at%, preferably 6 at% to 33 at%, more preferably 7 at% to 28 at%, even more preferably, based on the total amount of atoms in the black chromium plating layer including the chemical conversion layer. A black plated substrate according to any one of claims 1 to 6, comprising a total amount of carbon in the range 8 at% to 24 at%, most preferably 9 at% to 20 at%, even most preferably 10 at% to 16 at%. The black chromium plating layer is 12 at% to 40 at%, preferably 14 at% to 38 at%, more preferably 16 at% to 36 at%, even more preferably, based on the total amount of atoms in the black chromium plating layer including the chemical conversion layer. A black plated substrate according to any one of claims 1 to 7, comprising a total amount of oxygen in the range 18 at% to 34 at%, most preferably 20 at% to 31 at%, even most preferably 22 at% to 28 at%. The black chromium plating layer preferably contains 5 at% to 23 at%, preferably 6 at% to 21 at%, more preferably 7 at% to 19 at%, based on the total amount of atoms in the black chromium plating layer including the chemical conversion layer. The black color according to any one of claims 1 to 8, comprising a total amount of iron more preferably in the range 8 at% to 17 at%, most preferably 9 at% to 15 at%, even most preferably 10 at% to 13 at%. Plating substrate. The chemical conversion layer has a depth of 32 nm or more, preferably 35 nm or more, more preferably 38 nm or more, even more preferably 41 nm or more, and even more preferably 44 nm or more, most preferably 48 nm or more, and even most preferably 51 nm or more. The black plated substrate according to any one of claims 1 to 9. Claims 1 to 10, wherein the conversion layer has a maximum depth of 90 nm or less, preferably 80 nm or less, more preferably 70 nm or less, even more preferably 66 nm or less, and even more preferably 62 nm or less, most preferably 60 nm or less. The black plated substrate according to any one of . The black chromium plating layer has a thickness of 130 nm or more, preferably 160 nm or more, more preferably 190 nm or more, even more preferably 220 nm or more, even more preferably 250 nm or more, most preferably 275 nm or more, and still most preferably 300 nm or more. The black plated substrate according to any one of claims 1 to 11, having a total thickness including a chemical conversion layer. the conversion layer is free of metallic chromium or contains only up to 1.7 at% metallic chromium; preferably free of metallic chromium, based on the total number of elemental chromium and chromium atoms in the conversion layer; , or at most 1.5 at% chromium metal; more preferably no chromium metal, or at most 1.2 at% chromium metal, and even more preferably no chromium metal; Contains no or at most 1 at% chromium metal, and even more preferably no chromium metal or at most 0.8 at% chromium metal, and most preferably no chromium metal, or at most 0.8 at% chromium metal. Claims free of chromium or containing only up to 0.5 at% metallic chromium, and most preferably free of metallic chromium or containing only up to 0.3 at% metallic chromium. 13. The black plated substrate according to any one of 1 to 12. The conversion layer preferably comprises 40 at% to 75 at%, preferably 46 at% to 70 at%, more preferably 50 at% to 66 at%, most preferably 54 at%, based on the total number of elemental chromium and chromium atoms in the conversion layer. A black plated substrate according to any one of claims 1 to 13, comprising chromium in the form of chromium hydroxide in a total amount in the range ˜62 at%. 15. Claims 1 to 14, wherein in the chemical conversion layer, the atomic ratio of elemental chromium to elemental oxygen is less than 1, and/or in the black chromium plating layer without a chemical conversion layer, the atomic ratio of elemental chromium to elemental oxygen is greater than 1. The black plated substrate according to any one of .