JP2020049719A - Black-plated resin component - Google Patents

Abstract

To provide a black-plated resin component comprising a black chromium-plated layer composed of not yellowish trivalent chromium.SOLUTION: The black-plated resin component includes a resin base material, a base plated layer formed on the resin base material and a black chromium-plated layer which is formed on the base plated layer, is composed of trivalent chromium and has a film thickness of 0.15 μm or more. In the black-plated resin component, the chromium in the black chromium-plated layer is present in a state of metallic chromium, chromium oxide and chromium hydroxide, and in a surface region from the surface of the black chromium plated layer to at least a depth of 23 nm, a composition ratio of the metallic chromium, the chromium oxide and the chromium hydroxide satisfies inequalities: b+c>4a and c>0.8b (provided that a>0, b>0 and c>0), where a denotes the metallic chromium, b denotes the chromium oxide and c denotes the chromium hydroxide, and b* in L*a*b* color system of the black chromium plated layer measured from the surface region side is 3.0 or less.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a black-plated resin part used for decorative parts for vehicles, housing parts for electric products, and the like.

  In the fields of decorative parts for vehicles and housing products for electrical products, there is a growing need for a deep jet-black black appearance from the viewpoint of design and the like. Jet black color can be obtained with a black plating layer formed by cobalt chrome plating, chrome plating or the like.

  The jet-black color tone includes a yellowish color, a bluish color, and a color that is neither of them. The market needs a non-yellowish color. The applicant of the present invention first paid attention to the problem that the jet black color of the black plating layer made of trivalent chromium became yellowish when viewed through a chromate film formed thereon as a corrosion-resistant film. It has been shown that yellowing can be suppressed by using a coating made of chromium or molybdenum phosphate (Patent Document 1).

  In Example 1 of Patent Literature 1, the color tone of the black chrome plating layer viewed through the corrosion-resistant coating was 52.46 for L *, 0.67 for a *, and 4 for b * in the L * a * b * color system. .38, with little yellowing. However, there is a demand for a black color without yellowing as a market need.

JP-A-2017-71100

  Therefore, an object of the present invention is to provide a black-plated resin component provided with a black chromium plating layer made of trivalent chromium without yellowing.

  The present inventors have found that the state of chromium in the surface region of the black chromium plating layer made of trivalent chromium affects the yellowish tint, and as a result of intensive studies, the present invention has been reached.

The black chromium-plated resin product of the present invention comprises a resin substrate, a base plating layer formed on the resin base, and trivalent chromium formed on the base plating layer and having a thickness of 0.15 μm or more. In a black chrome-plated resin part including a plating layer,
The chromium in the black chromium plating layer exists in a state of chromium metal, chromium oxide, and chromium hydroxide. In a surface region having a depth of at least 23 nm from the surface of the black chromium plating layer, chromium metal, chromium oxide, and chromium hydroxide are present. When the composition ratio of a is chromium metal a, chromium oxide b, and chromium hydroxide c (where a> 0, b> 0, c> 0), b + c> 4a, and c> 0.8b Wherein the b * in the L * a * b * color system of the black chrome plating layer measured from the surface region side is 3.0 or less.

[Action]
In a black chromium plating layer made of trivalent chromium, a relation of b + c> 4a and c> 0.8b is satisfied in a surface region having a depth of at least 23 nm from the surface, and the black chromium plating layer measured from the surface region side When b * in the L * a * b * color system is 3.0 or less, the black chrome plating layer does not have yellowishness. Although the mechanism has not been clearly elucidated yet, it is presumed that a large amount of b + c (particularly c) is a main factor for reducing yellowness.

  ADVANTAGE OF THE INVENTION According to this invention, the black plating resin component provided with the black chromium plating layer which consists of trivalent chromium without yellowing can be provided.

It is a typical sectional view of the black plating resin parts of samples 1-13. It is a graph which shows the relationship between the film thickness of the surface deteriorated layer in a black chromium plating layer of samples 1-13, and a * or b *.

1. Resin Substrate The resin of the resin substrate may be thermoplastic or thermosetting, and is not particularly limited. However, acrylonitrile-butadiene-styrene copolymer (ABS) resin, polycarbonate (PC) resin, PC / ABS resin, acrylic resin Styrene resin, polyamide resin, polypropylene resin, vinyl chloride resin, polyurethane resin and the like. ABS resin and PC / ABS resin are preferred from the viewpoint of strength, durability and the like.
On the resin base material, a conductive layer necessary for electrolytic plating of the next base plating layer is formed. Although it does not specifically limit as a conductive layer, An electroless nickel plating layer can be illustrated.

2. Base Plating Layer The base plating layer preferably includes a copper plating layer and a nickel plating layer in this order. It is preferable that the uppermost layer of the base plating layer is a nickel plating layer, and a black chromium plating layer is formed on the nickel plating layer. The copper plating layer follows the resin base material well because of its high ductility, and the nickel plating layer keeps the black chrome plating layer beautiful and electrochemically corrosion-proof. The specific configuration of the nickel plating layer is not particularly limited, and may be a single layer or a plurality of layers.

3. Black Chromium Plating Layer The thickness of the black chromium plating layer is set to 0.15 μm or more as described above in order to sufficiently conceal the underlying plating layer to obtain jet black. The upper limit of the thickness of the black chromium plating layer is not particularly limited, but is preferably 1 μm. If it exceeds 1 μm, the internal stress of the film increases, and the film is easily broken.
As the surface region (at least 23 nm deep from the surface), a mode in which the inside of the black chromium plating layer (base material) is altered is a region of a surface altered layer, a mode in which the entire region of the black chromium plating layer is formed, and the like. Can be illustrated. Examples of the surface altered layer include a layer altered by oxygen, hydrogen, or water vapor.

[About the color tone of the black chrome plating layer measured from the surface area side]
The reason why b * in the L * a * b * color system is 3 or less as described above is to eliminate blackish tint. b * is more preferably 1 or less. This is because it has a slightly bluish black color and more closely matches the needs of the market. The lower limit of b * is not particularly limited, but is preferably -10. If b * is less than -10, the bluish color is strong and the use is limited.
a * is not particularly limited, but is preferably -3 to 3. If a * is less than -3, the green color is strong and the application is limited. If a * is more than 3, the red color is strong and the application is limited.
L * is not particularly limited, but is preferably 30 to 54. If L * is less than 30, the blackness is strong and the metallic feeling is reduced, and if it exceeds 54, the blackness is weak and the jet-blackness is reduced.

It is preferable that the black chromium plating layer contains Fe because corrosion resistance is improved. Further, it is preferable that the black chromium plating layer contains Co, Mn, or Mo, because the plating adhesion is improved.
The trivalent chromium compound used in the trivalent chromium plating bath is not particularly limited, but chromium sulfate (Cr ₂ (SO ₄ ) ₃ ), chrome alum (CrK (SO ₄ ) ₂ ), chromium nitrate (Cr (NO _{3) 3} ), chromium chloride (CrCl ₃ ), chromium acetate (Cr (CH ₃ COO) ₃ ) and the like.

4. Corrosion resistant film It is preferable to provide a corrosion resistant film on the black chromium plating layer. Examples of the corrosion-resistant film include a chromate film and a film made of chromium phosphate or molybdenum phosphate described in Patent Document 1. The film made of chromium phosphate or molybdenum phosphate preferably has a thickness of 7 nm or more, more preferably 20 nm or less.

5. Applications of black plated resin parts For decorative parts for vehicles (radiator grills, fenders, garnishes, wheel caps, back panels, air spoilers, emblems, etc.), and for electric products (mobile phones, smartphones, personal digital assistants, game machines, etc.) Case parts and the like can be exemplified. In particular, decorative parts for vehicles that are exposed to the weather are required to have high corrosion resistance, and thus are highly effective when the present invention is applied.

  As the black-plated resin parts shown in FIG. 1, samples 1 to 13 mainly showing the differences in Table 1 were produced, and the black chromium plating layer was analyzed and the color was measured.

[Common Items of Samples 1 to 13]
As shown in FIG. 1, all of the black-plated resin parts of Samples 1 to 13 are made of an ABS resin resin base (with an electroless nickel plating layer as a conductive layer) and copper formed on the resin base. A base plating layer including a plating layer, a semi-bright nickel plating layer, a bright nickel plating layer, and a microporous-nickel plating layer in this order, and a black chromium plating layer made of trivalent chromium formed on the nickel plating layer. It is provided with. It is preferable to form a corrosion-resistant film on the black chromium plating layer, but in samples 1 to 13, no corrosion-resistant film was formed.

  In order to produce a black-plated resin component, first, a pretreatment was performed on the surface of the resin substrate to impart conductivity to the surface of the resin substrate. In the pretreatment, the ABS resin base material is immersed in chromic acid to perform an etching treatment, a Pd—Sn metal complex is applied to the surface after the etching treatment and activated, and then an electroless nickel plating layer as a conductive layer is formed. did.

  Subsequently, a base plating treatment was performed on the resin base material provided with conductivity by the pretreatment. In the base plating process, the resin substrate is immersed in various metal plating baths and electroplated so that a copper plating layer, a semi-bright nickel plating layer, a bright nickel plating layer, and a microporous nickel plating layer are laminated in this order. Was processed.

Next, a black chrome plating process was performed on the resin substrate subjected to the base plating process. In the black chromium plating treatment, the resin substrate subjected to the base plating treatment is immersed in a trivalent chromium plating bath, the bath temperature is 40 ° C., the pH value is 3.2, the predetermined cathode current density, the predetermined anode current density, and the film forming speed are 0. Electroplating was performed under the conditions of 0.07 μm / min and a plating time of 5 minutes, whereby a black chromium plating layer having a predetermined thickness was formed on the microporous nickel plating layer. The trivalent chromium plating bath used was an aqueous solution containing the following components (the trivalent chromium compound is a basic chromium sulfate contained in trichrome aditib), and the pH was adjusted using 35% hydrochloric acid. The value was adjusted to 3.2.
Wako Pure Chemical Industries boric acid 63g / L
Atotech Trichrome Azib 400g / L
Atotech Trichrome Stabilizer 100ml / L
Atotech Trichrome Regulator 3ml / L
Atotech Trichrome Collector 2ml / L
Atotech Trichrome Graphite Makeup 100ml / L
Atotech Trichrome Graphite Maintenance Prescribed formula

[Differences of Samples 1 to 13]
(1) In the above black chrome plating treatment, the composition of Atotech Trichrome Graphite Maintenance (hereinafter referred to as "M agent") was set to 20 ml / L for samples 1 to 4 and 30 ml / L for samples 5 to 13. .

(2) The cathode current density and the anode current density were set to 5 A / dm ² (Table 1 “medium”) for Samples 9 and 12, and 2.5 A / dm ² (Table 1 “Low”) for Samples 8 and 11, Samples 1 to 7, 10, and 13 were set to 10 A / dm ² (Table 1 “High”).
Due to this difference in current density, the thickness of the black chromium plating layer was 0.53 μm in Samples 9 and 12, 0.252 μm in Samples 8 and 11, and 1.10 μm in Samples 1 to 7, 10, and 13.

(3) After the above black chromium plating treatment, before the analysis and color measurement of the black chromium plating layer, the state of the sample was set to immediately after plating in samples 8 to 10, and the samples 2 and 5 were stored in vacuum (room temperature). Samples 3 and 6 were left in the atmosphere (left at room temperature for 18 days). Samples 1, 4, 7, and 11 to 13 were subjected to an acceleration test (in a thermostat, at a temperature of 80 ° C. and a humidity of 80 ° C.). Between 20% and 80%, the sample was allowed to stand for 3 hours / cycle in air for a predetermined period of time. The predetermined time of the accelerated test was 90 days for Sample 1 and 18 days for Samples 4, 7, 11 to 13.

  With respect to the black plated resin parts of Samples 1 to 13 prepared as described above, the analysis and color measurement of the black chrome plated layer were performed as follows.

<Analysis of black chrome plating layer>
Hard X-ray photoelectron spectroscopy (HAXPES) analysis of the black chromium plating layer was performed with the following equipment.
-Beam line: Large synchrotron radiation facility SPring-8 BL16XU (Photon energy: 7947.58 eV)
・ Analyzer: R4000 (Take-off angle: 85 °) from VG Scienta

Peak separation is described in M.E. C. Biesinger et al. , Appl. Surf. Sci. 257, 2717 (2011) was referred (the oxide was a broad one). From the results of the peak separation of Cr2p, the following was found in all the samples.
Chromium in the black chromium plating layer is present in a state of metallic chromium (Cr), chromium oxide (Cr ₂ O ₃ ), and chromium hydroxide (Cr (OH) ₃ ).
The composition ratio of chromium metal, chromium oxide, and chromium hydroxide differs between the inside and the surface region of the black chromium plating layer, and the surface region has a depth from the surface of the black chromium plating layer of about 10 to several tens nm. , And considered to be a surface altered layer (even samples 8 to 10 immediately after plating are considered to be surface altered layers).

The thickness of the surface-altered layer is set to B. R. Stormmeier, Surf. Interface Anal. 15, 51 (1990) (as Cr ₂ O ₃ / Cr).
Table 1 shows the thickness of the surface altered layer and the composition ratio of chromium metal, chromium oxide, and chromium hydroxide determined as described above. Table 1 shows (b + c) / a and c / b, where a is chromium metal, b is chromium oxide, and c is chromium hydroxide.

<Color measurement>
The color tone (L * a * b * color system) of the black chrome plating layer was measured from the surface region side using a spectrophotometer (CM-700d, manufactured by Konica Minolta). The measurement conditions were: measurement mode SCI, observation conditions: 10 ° field of view, observation light source D65, measurement diameter / illumination diameter = φ3 / φ6. Table 1 shows the measured values in the L * a * b * color system.

From the measurement results shown in Table 1, the following can be understood.
(1) The larger the amount of the M agent added, the larger the thickness of the surface altered layer.
(2) The higher the current density, the larger the thickness of the surface altered layer.
(3) As the state after the black chromium plating treatment becomes vacuum storage → left in the air → accelerated test, the thickness of the surface altered layer increases, metal chromium a decreases, and the sum of chromium oxide and chromium hydroxide ( b + c) increases.
(4) The film thicknesses of the surface altered layers of Samples 1 to 13 and a * and b * were plotted in FIG. 4. From FIG. 4, a strong correlation between the thickness of the surface altered layer and b * is seen, and b * suddenly decreases when the thickness of the surface altered layer is in the range of 20 to 25 nm.

  Samples 1, 4, 7, and 13 within the scope of the present invention have no yellowish tint on the black chromium plating layer, and samples 2, 3, 5, 6, 8 to 12 outside the scope of the present invention have black chromium plating layers. The layer was yellowish.

  It should be noted that the present invention is not limited to the above-described embodiment, and can be embodied with appropriate modifications without departing from the spirit of the invention.

In the field of decorative parts for vehicles and housing parts for electric products, there is a growing need for a deep jet black appearance in terms of design and the like. Jet black color can be obtained with a black plating layer formed by cobalt chrome plating, chrome plating or the like.

The black-plated resin part according to the present invention is a black chromium plating having a thickness of 0.15 μm or more comprising a resin base, a base plating layer formed on the resin base, and trivalent chromium formed on the base plating layer. A black plated resin part including
The chromium in the black chromium plating layer exists in a state of chromium metal, chromium oxide, and chromium hydroxide. In a surface region having a depth of at least 23 nm from the surface of the black chromium plating layer, chromium metal, chromium oxide, and chromium hydroxide are present. When the composition ratio of a is chromium metal a, chromium oxide b, and chromium hydroxide c (where a> 0, b> 0, c> 0), b + c> 4a, and c> 0.8b Wherein the b * in the L * a * b * color system of the black chrome plating layer measured from the surface region side is 3.0 or less.

From the measurement results shown in Table 1, the following can be understood.
(1) The larger the amount of the M agent added, the larger the thickness of the surface altered layer.
(2) The higher the current density, the larger the thickness of the surface altered layer.
(3) As the state after the black chromium plating treatment becomes vacuum storage → left in the air → accelerated test, the thickness of the surface altered layer increases, metal chromium a decreases, and the sum of chromium oxide and chromium hydroxide ( b + c) increases.
(4) The film thicknesses and a * and b * of the surface altered layers of Samples 1 to 13 were plotted in FIG . FIG. 2 shows a strong correlation between the thickness of the surface-altered layer and b *, and b * suddenly decreases when the thickness of the surface-altered layer is in the range of 20 to 25 nm.

Claims (1)

A black chromium-plated resin component including a resin base, a base plating layer formed on the resin base, and a black chromium plating layer having a thickness of 0.15 μm or more and made of trivalent chromium formed on the base plating layer At
The chromium in the black chromium plating layer exists in a state of chromium metal, chromium oxide, and chromium hydroxide. In a surface region having a depth of at least 23 nm from the surface of the black chromium plating layer, chromium metal, chromium oxide, and chromium hydroxide are present. When the composition ratio of a is chromium metal a, chromium oxide b, and chromium hydroxide c (where a> 0, b> 0, c> 0), b + c> 4a, and c> 0.8b Wherein the b * in the L * a * b * color system of the black chromium plating layer measured from the surface region side is 3.0 or less.

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