JPH10259317A - Highly weatherable metallic pigment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metallic pigment which can form a surface exhibiting a high-grade metallic appearance and excellent in brightness and durability when mixed into a resin coating material, a printing ink, a resin compsn. for plastic moldings, etc. SOLUTION: This pigment comprises a flaky substrate material and a thin metal film which is formed thereon by sputtering, has a thickness of 50-300Å, and comprises a silver alloy layer contg. 10-40 atom % at least one element selected from among Si, Zr, Cr, and Al and a composite oxide layer contg. an added element and Ag. Pearl mica or glass flakes having an average flake size of 10-300 μm and an average thickness of 0.1-20 μm are used as the substrate material. Since the thin metal film is formed by sputtering, a thin silver alloy layer covers the whole surface of the flaky substrate and the oxide layer formed on the surface of the silver alloy layer gives the pigment a higher weatherability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly weather-resistant metallic pigment to be mixed in a metallic paint for coating an automobile body, exterior building materials and the like.

[0002]

2. Description of the Related Art The color tone of automobile bodies and exterior building materials has been improved by various methods in order to enhance harmony with the surroundings, distinguishability, and design. For example, in a top coat for an automobile body, a paint containing a metallic pigment such as pearl mica or aluminum flake is used in order to obtain a brilliant metallic surface. Aluminum flakes are excellent in concealing properties and glitter, but have problems in corrosion resistance and weather resistance. Therefore, pigments having a high-grade metallic feeling are mainly based on pearl mica, glass flakes, etc. is there. As pearl mica, there is known a pearl mica in which the entire surface of mica is coated with titania so as to improve the design property by using an interference color resulting from the high refractive index of titania. However, pearl mica has some problems in weather resistance and poor concealing properties and glitter, so various improvements have been proposed. For example, a metallic pigment in which a metal coating layer is formed on the entire surface of mica by plating (Japanese Patent Laid-Open No. 57-16055), a lower oxide layer of titanium is formed, and then the entire surface of mica is further coated with a titania layer. Metallic pigment, a metallic pigment in which metallic brilliant portions are formed in an island shape on the surface of pearl mica
-108267).

[0003]

SUMMARY OF THE INVENTION Metallic pigments in which the entire surface of mica is coated with a plating metal (JP-A-57-161)
No. 055), the concealing property, the weather resistance and the like are improved by the plated metal layer. However, since a metal thin film is formed by plating, it is inevitable that minute irregularities occur on the surface of the thin film, which causes a reduction in glitter. The decrease in glitter due to minute irregularities on the surface of the thin film is caused by a metallic pigment in which metallic glitter portions are formed in an island shape (JP-A-1-10826).
No. 7). On the other hand, a metallic pigment coated with mica with a titania layer via a titanium lower oxide layer tends to lack concealing properties, glitter, weather resistance, and the like. As a method for improving the weather resistance of pearl mica, a method of treating titania-coated mica with acid chromium oxide (Japanese Patent Application Laid-Open No. 54-96534), a method using hydrated zirconium and a hydrated oxide such as Co, Mn, and Ce. There have been reported a method of adhering (Japanese Patent Application Laid-Open No. 1-292067), a method of coating with a chloride of Se and Sb, and further treating the same with silica or alumina (Japanese Patent Application Laid-Open No. 4-249584). However, any of the post-treatments cannot provide sufficient weather resistance required for applications such as automobile bodies and exterior building materials. In addition, the post-treatment may increase yellowness or reduce the glitter.

[0004] Furthermore, such a post-treatment is usually carried out with an acid
This is a wet method using an alkali reaction. Therefore, in order to obtain a product of stable quality, strict control is required for the solution concentration, the reaction temperature, and the like, and many steps such as washing, filtration, drying, classification, and waste liquid treatment are required. as a result,
This leads to a rise in manufacturing costs. The present invention has been devised to solve such a problem, and by forming a silver alloy layer and a composite oxide layer of an added alloy element and Ag on the surface of a flaky substrate, An object of the present invention is to provide a metallic pigment which is excellent in weather resistance, and has both concealing properties and glitter.

[0005]

In order to achieve the object, a highly weatherable metallic pigment of the present invention has a thickness of 50 to 300 mm comprising a silver alloy layer and a composite oxide layer of Ag and an element added as an alloy. The metal thin film is formed on the surface of the scaly substrate by a sputtering method. As the scaly substrate, pearl mica or glass flake having an average particle size of 10 to 300 μm and an average thickness of 0.1 to 20 μm is used. The silver alloy layer and the composite oxide layer may include, for example, one or more of Si, Zr, Cr, and Al
It is formed from a silver alloy containing 40 atomic%.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION For a scaly base material, pearl mica, glass flake, aluminum flake, graphite, molybdenum disulfide, plate-like iron oxide and the like are used. Above all, an average particle size of 10 to 300 μm (preferably 20 to 100 μm),
Average thickness 0.1-20 μm (preferably 1-10 μm)
Pearl mica and glass flakes having the following sizes are suitable. With glass flakes having an average particle size of less than 10 μm, it is difficult to orient in a certain direction in the coating film, and no glitter is exhibited.
Conversely, if the average particle size exceeds 300 μm, a fine metallic feeling cannot be obtained. Further, it is difficult to produce glass flakes having an average thickness of less than 0.1 μm, and if the average thickness exceeds 20 μm, the glass flakes are close to the thickness of the coating film, and the smoothness of the coating film surface is impaired. Glass flakes are not restricted in their material, but include elemental glass, hydrogen bonded glass, oxide glass, fluoride glass, chloride glass,
Sulfide glass, carbonate glass, nitrate glass, sulfate glass and the like are used. Considering price and performance, oxide glass such as silicate glass, alkali silicate glass, soda-lime glass, lead glass, barium glass, and borosilicate glass is preferable.

It is said that the best way to obtain an excellent metallic pigment is to laminate silver having light-reflecting properties on the surface of a scaly substrate. However, silver has a problem in that it is easily oxidized, and when it reacts with a sulfide, the glitter tends to be reduced. Moreover, it is considered that it is technically extremely difficult to improve the corrosion resistance of silver only by post-treatment such as chromium hydroxide treatment. On the other hand, the present inventors, when a silver alloy layer of a specific composition is laminated on the surface of the flaky substrate, while maintaining the original color tone and luster of silver,
It has been found that the outermost layer is covered with several atomic layers of a thin composite oxide layer that is naturally formed by contact with air, and that the composite oxide layer significantly improves weather resistance.

The silver alloy used in the present invention contains, as an alloy component, one or more of Si, Zr, Cr, and Al which form a composite oxide having good corrosion resistance, and is formed by contact with air. These alloy elements are also taken into the outermost composite oxide layer. When Ag ₂ O in the composite oxide layer is eluted by the corrosion reaction, SiO ₂ ,
The content of ZrO ₂ , Cr ₂ O ₃ or Al ₂ O ₃ increases. Since these oxides have excellent corrosion resistance, the corrosion resistance of the composite oxide layer itself improves with the elution of Ag. Further, even under severe use conditions in which the composite oxide layer itself is eluted by the corrosion reaction, the effect of the silver alloy is maintained until the entire silver alloy layer is eluted. Therefore, when compared with a thin post-treatment film formed of ordinary chromium hydroxide, etc.,
The corrosion life is significantly increased. In the present invention, since the composite oxide layer formed on the surface of the silver alloy utilizes the effect of improving the weather resistance, after the conventional chromium hydroxide treatment, zirconia hydroxide treatment, silica treatment, alumina treatment, etc. No processing is required.

As silver alloys, Ag-Si, Ag-Z
r, Ag-Cr, Ag-Al, Ag-Si-Zr, Ag
-Si-Al, Ag-Si-Zr-Al and the like. The content of alloy components such as Si, Zr, Cr, and Al contained in the silver alloy is 10 to 40 atomic% (preferably 20%).
-30 atomic%). If the content is less than 10 atomic%, a composite oxide layer having a sufficient thickness is not formed on the surface of the silver alloy layer, and the improvement in weather resistance becomes insufficient. Conversely, when a large amount of alloy components exceeding 40 atomic% is contained, the color tone of the silver alloy changes, and the beautiful silver white originally exhibited by silver does not appear. The silver alloy used in the present invention is Si, Z
In order to form a dense and strong oxide film on the surface when alloyed in addition to r, Cr, and Al, thereby improving the weather resistance, Zn, Sb, Co, Mn, Ti, Mo, T
a, Nb, W, N, B, P, etc.
It can also be contained at a ratio of atomic%.

The silver alloy layer and the composite oxide layer have a thickness of 50-30.
It is formed on the surface of the scaly substrate with a thickness of 0 ° (preferably 100 to 200 °). If the thickness is less than 50 °, the surface of the flaky base material cannot be uniformly coated with the silver alloy layer and the composite oxide layer. Conversely, if the film thickness exceeds 300 °, the effect of increasing the film thickness will be saturated, and expensive silver will be consumed in large quantities, causing an increase in manufacturing cost. As a method of coating the scaly substrate with a silver alloy, ion plating, vacuum evaporation, or the like can be considered. However, in order to form a stable coating layer without adversely affecting the properties of the flaky substrate and the coating layer, the powder sputtering method developed by the present inventors is most suitable.
Incidentally, in the vacuum deposition method, the melting point and the vapor pressure of Si, Zr, Cr or Al and Ag are different, and therefore, it is difficult to control the composition. Further, when the temperature at the time of coating exceeds 600 ° C. as in the CVD method, the glass flakes used as the scaly base material are softened, and the smoothness of the surface which affects the glitter decreases.

In this type of powder sputtering method, a method of charging powder into a rotating drum and sputtering powder particles fluidized by rotation of the rotating drum is disclosed in
153068), a method of sputtering metal onto a repeated falling flow of powder (Japanese Patent Application Laid-Open No. 62-2501).
No. 72 gazette). In the powder sputtering, for example, an apparatus whose configuration is shown in FIG. 1 is used. In this powder sputtering apparatus, a rotating drum 1 is supported by two rolls 2, and one of the rolls 2 is rotated by a motor 3. Inside the rotating drum 1, two sputtering sources 4 are arranged, and the loaded flaky base material 5 is sputtered.

Above the rotating drum 1, a decompression processing chamber 7 having a heating coil 6 on its outer periphery is arranged. The bottom of the decompression processing chamber 7 is connected to a rotating drum 1 via a supply pipe 9 having a valve 8. It is connected to the. The supply pipe 9 has a double pipe structure in which an Ar gas introduction pipe 10 is inserted inside a portion below the valve 8, and is inserted into the inside of the rotary drum 1 from a side surface, and a tip of the rotary drum 1 is provided. Extends to the bottom. A branch pipe 11 is attached to the supply pipe 9 below the valve 8, and the tip of the branch pipe 11 is connected to the fluid jet mill 1.
2 are connected. The outlet side of the fluid jet mill 12 is
It is connected to the upper part of the decompression processing chamber 7 via the circulation pipe 13. Valves 14 and 15 are inserted into the branch pipe 11 and the circulation pipe 13, and a solid-gas separation device 16 is connected to the circulation pipe 13. The scaly substrate 5 metal-coated by sputtering in the rotating drum 1 is sent from the branch pipe 11 and the circulation pipe 13 to the decompression processing chamber 7 and repeatedly subjected to the sputtering process until a film having a predetermined thickness is formed. The scaly substrate 5 on which a film having a predetermined thickness is formed is applied to the solid-gas separator 1
Collected at 6.

When the silver alloy layer is formed by the powder sputtering method, a target prepared by a sintering method, a melting method, or the like is used. In the case of a target composed of a plurality of crystal phases, the target is adjusted so as to have a target average composition of the silver alloy layer. Further, a target in which a metal to be alloyed is embedded in a silver plate which is a main component of a target silver alloy layer, a target in which a plurality of single metals are incorporated, or the like can be used. Generally, it is said that the thicker the coating layer applied to the substrate, the larger the irregularities on the surface of the coating layer and the lower the glitter. For example, in the case of electroless plating,
It is said that the entire surface of the powder cannot be uniformly coated unless the thickness is increased to 0 ° or more.
Even the following thin films can sufficiently coat the entire surface uniformly. Therefore, more excellent glitter is imparted to the flaky substrate. In addition, since the consumption of expensive silver alloy can be reduced, the manufacturing cost can also be reduced.

In the powder sputtering method, a phenomenon in which metal atoms excited to a plasma state collide with the surface of the scaly substrate at high speed is repeated. TiO ₂ , SiO ₂ , Al ₂ O constituting the flaky base material by the collision energy
Oxide such as ₃ reacts with the silver alloy, and Ag-Si-
Compounds such as O and Ag-Al-O are formed. As a result, a film having better adhesion than electroless plating is formed. The compound layer formed at the interface serves as a nucleation starting point for film formation during coating. In the powder sputtering method, many nucleation starting points are formed extremely finely and densely. Therefore, the surface of the scaly substrate can be uniformly coated with a small amount of silver alloy, and the formed coating layer also has a dense structure. Therefore, the obtained metallic pigment has excellent glitter.

On the other hand, in the electroless plating, a pretreatment for activating the surface of the scaly substrate with Pd or the like is performed in advance.
It is said that the portion to which Pd adheres becomes a nucleation point for film formation during electroless plating. Pd, a physical adsorption phenomenon
Is significantly weaker than the sputtering method,
Also, the adhesion density of Pd is considerably smaller than the collision density of metal atoms excited in a plasma state. Therefore, it is presumed that the film formed by the electroless plating is likely to be rough, and there is a limit in improving the glitter. After uniformly coating the surface of the scaly base material with a silver alloy by the sputtering method, in order to improve the dispersibility to the paint and the adhesion to the resin, a coating treatment using an organic substance such as a fatty acid and various coupling agents are performed. The used surface treatment may be performed. Examples of the coupling agent include γ-aminopropyltriethoxysilane, N-β-aminoethyl-γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, a titanium-based coupling agent, and a zirconia-based coupling agent. Agents, aluminum-based coupling agents and the like are used.

The amount of the metallic pigment coated on the scaly substrate with the silver alloy is preferably adjusted to 0.1 to 30 parts by weight based on 100 parts by weight of the vehicle component (solid content). . If the amount of the metallic pigment is too small, a high-quality metallic feeling with depth cannot be obtained. The upper limit of the compounding amount is not particularly limited, and depends on the type of resin, required physical properties of the molded product, and the like.
Usually, it is appropriately determined within the range of up to 20 parts by weight, particularly preferably up to 5% by weight. The vehicle component is preferably a curable resin composition containing a base resin and a crosslinking agent as main components. Examples of the substrate resin include an acrylic resin, a polyester resin, and an alkyd resin having a crosslinkable functional group, and a resin having as high a transparency as possible is used. As the cross-linking agent, a methylolated or alkyletherified melamine resin, a urea resin, a polyisocyanate compound, or the like is used. Also,
A self-curing resin, a thermosetting resin, or the like can be used, and a resin colored with a dye, a pigment, or the like can also be used. Solvents include
Organic solvents and water for paints are used.

[0017]

【Example】

Example 1: Using the powder sputtering apparatus of FIG.
90 atomic% Ag-10 atomic% S on the surface of silver pearl mica pigment (manufactured by Marl Co., Ltd., average particle size: 10 μm, average thickness: 0.1 μm) so that the film thickness becomes 200 °.
The i alloy was coated. Two silver alloy sputtering sources 4 were arranged on a rotating drum 1 having an inner diameter of 200 mm and an axial length of 200 mm. As the sputtering source 4,
A magnetron type having a frequency of 13.56 MHz and an output of 1.5 KW was used. After 100 g of the pearl mica pigment 5 was charged, the pressure in the vacuum processing chamber 7 was reduced to 3.0 × 10 ⁻³ Pa,
Ar gas was introduced at a flow rate of 15 cm ³ / min from the Ar gas introduction pipe 10, and the pearl mica pigment 5 was suctioned and transferred to the decompression processing chamber 7 via the branch pipe 11, the fluid jet mill 12 and the circulation pipe 13. Then, it was dried and degassed by heating it to 200 ° C. for 30 minutes by the heating coil 6 in the decompression processing chamber 7.

Next, after completely replacing the atmosphere of the rotating drum 1 with Ar gas, the pearl mica pigment 5 in the decompression processing chamber 7 is dropped from the supply pipe 9 onto the rotating drum 1, and the rotating drum 1 is rotated at a speed of 5 rpm. 3.0 × 10 ^-1 P
The sputtering was performed from the sputtering source 4 under the reduced pressure atmosphere of a. After 10 minutes, the sputtering was stopped, the pressure in the vacuum processing chamber 7 was reduced, and the Ar gas was introduced from the Ar gas introduction pipe 10.
A gas was introduced, and the pearl mica pigment 5 was sucked and returned to the decompression treatment chamber 7 via the fluid jet mill 12, and the pearl mica pigment 5 agglomerated during sputtering was loosened as much as possible into individual particles. The pearl mica pigment 5 returned to the decompression processing chamber 7 was covered with a silver alloy having a thickness of 10 °. By repeating this sputtering 20 times,
After growing the silver alloy film up to 200 °, it was recovered from the solid-gas separator 16.

Examples 2 to 7: In the same manner as in Example 1, the surface of the pearl mica pigment was coated with Ag-Si, 70Ag-Si,
Each alloy layer of Ag-Si, Ag-Zr, Ag-Cr and Ag-Al was formed. Average particle size of pearl mica used,
Table 1 shows the average thickness and the composition and thickness of the formed silver alloy layer. Comparative Example 1 A silver layer having a thickness of 200 ° was formed on the surface of a pearl mica pigment in the same manner as in Example 1.

Using a total of eight types of pigments obtained in Examples 1 to 7 and Comparative Example 1, coated steel sheets were produced as follows. To 10 parts by weight of each pigment, 8 parts by weight of toluene was added and stirred, and the pigment was uniformly dispersed in toluene. Next, a thermosetting acrylic resin varnish (Amaltex 44) is added to the dispersion.
8-O 60 parts by weight of Mitsui Toatsu Chemical Co., Ltd., 12 parts by weight of melamine resin varnish [Uban 20N-60 made by Mitsui Toatsu Chemicals Co., Ltd.] and a solvent (65% by weight of toluene and 35% by weight of n-butanol) (Solvent) was added, and a metallic paint was prepared by stirring with a disper for 30 minutes. 0.8m thick for the original coating
A polished steel plate of m, width 300 mm and length 500 mm was used. After the polished steel sheet is treated with zinc phosphate according to a conventional method, a cationic electrodeposition paint (Powertop U-30 manufactured by Nippon Paint Co., Ltd.) is electrodeposited and heated at 160 ° C. for 30 minutes to give a dry film thickness of 20 μm. An undercoat was formed. Then, an intermediate coating (Olga P-2 Gray, manufactured by Nippon Paint Co., Ltd.) was applied and heated at 140 ° C. for 30 minutes to form an intermediate coating having a dry film thickness of 35 μm.

The original coating plate on which the undercoat film and the intermediate coat film were formed was coated with the metallic paint prepared as described above. Prior to painting, paint thinner (Nippe 298 Nippon Paint Co., Ltd.) so that the viscosity at 15 ° C. becomes 15 seconds in a No. 4 Ford Cup test.
Diluted the metallic paint. The metallic paint whose viscosity was adjusted was electrostatically spray-coated on the intermediate coat with a spray gun to form a metallic coat having a dry film thickness of 15 μm.
Next, a wet-on-wet clear paint (Super Rack 128M-1 manufactured by Nippon Paint Co., Ltd.)
, And heated at 140 ° C. for 30 minutes to obtain a total dried film thickness of 1
It was 40 μm.

Thus, Examples 1 to 7 and Comparative Example 1
, Coated steel sheets were prepared for a total of eight samples. The metallic feeling and weather resistance of the obtained coated steel sheet were investigated. The metallic feeling was evaluated by a 60-degree specular reflectance using a digital variable-angle gloss meter (UGV-5K, manufactured by Suga Test Instruments Co., Ltd.). Weather resistance was investigated in a 1,000 hour QUV test. In the QUV test, after turning on the ultraviolet lamp at about 60 ° C. for 4 hours, non-lighting for about 4 hours with moisture or moisture condensation at about 50 ° C. was defined as one cycle, and this cycle was repeated three times in 24 hours. . In this test, the test panel will be exposed to simulated hot tropical daytime conditions followed by warm, humid nighttime conditions during which moisture or moisture condenses on the panel surface. While the panel is wet with condensed moisture, the panel is exposed to intense ultraviolet light according to the repetition of the ultraviolet lighting process. The coated steel sheet exposed to the QUV test was periodically removed from the tester, and the change in appearance was measured using a color difference meter and a digital variable-angle gloss meter. Then, for each test piece, the amount of change from before the test was determined as the color difference ΔE and the gloss retention%. As can be seen from Table 1 showing the above test results, the coated steel sheet produced using the metallic pigment according to the present invention has suppressed changes in color tone and glossiness, and has sufficient weather resistance for practical use. It can be seen that it has an extremely excellent metallic feeling. On the other hand, the coating film using the pigment of Comparative Example 1 was inferior in both metallic feeling and weather resistance.

[0023]

Examples 8 to 14: In the same manner as in Example 1,
Transparent glass flakes (average particle size: 3 manufactured by Barotini)
(00 μm, average thickness: 20 μm) was coated with various silver alloys by a sputtering method. Comparative Example 2: In the same manner as in Example 1, a surface of the same transparent glass flake as in Examples 8 to 14 was coated with silver at a thickness of 200 °. Using a total of eight types of pigments obtained in Examples 8 to 14 and Comparative Example 2, a coated steel plate was produced in the same manner as described above, and the performance of the coating film was investigated. Table 2
As can be seen from the survey results, in this case also, by providing the silver alloy layer on the surface of the transparent glass flake, the glass flake covered with the silver layer was used as a metallic pigment in comparison with the coating film of Comparative Example 1, A coating film excellent in glitter and weather resistance was obtained.

[0025]

[0026]

As described above, the highly brilliant metallic pigment of the present invention is provided with a silver alloy layer having excellent corrosion resistance on the surface of a scaly substrate by a sputtering method, and an additive element on the surface of the silver alloy layer. To form a composite oxide layer of Ag and Ag. Since the coating is performed by the sputtering method, the scale-like substrate surface can be uniformly covered with a thin film thickness as compared with the conventional method, and a high-quality metallic pigment can be obtained in which an increase in consumption of expensive silver alloy is suppressed. When this metallic pigment is mixed with a paint and applied to a steel sheet, a coated steel sheet having excellent weather resistance and brilliancy can be obtained.
Used as a body for two-wheel drive vehicles, exterior building materials, etc. Further, it can be applied to reflective tapes, display materials, signboards and the like by being mixed with printing ink, and can be kneaded into various plastic molded products and used as an agent for preventing the generation of weld lines.

[Brief description of the drawings]

FIG. 1 A powder sputtering apparatus for coating a silver alloy on a scaly substrate surface

[Explanation of symbols]

1: rotating drum 2: roll 3: motor 4:
Sputtering source 5: Scaly substrate 6: Heating coil 7: Decompression processing chamber 8: Valve 9: Supply pipe 10: Ar gas introduction pipe 11: Branch pipe 12: Fluid jet mill 13: Circulation pipe 1
4, 15: valve 16: solid-gas separation device

Claims (2)

[Claims] 1. A metal thin film comprising a silver alloy layer containing 10 to 40 at% of one or more of Si, Zr, Cr and Al and a composite oxide layer of an additive element thereof and Ag having a thickness of 50 to 300 ° are provided. A highly weather-resistant metallic pigment formed on the surface of a flaky substrate by a sputtering method. 2. The highly weather-resistant metallic pigment according to claim 1, wherein the flake-like base material is pearl mica or glass flake having an average particle size of 10 to 300 μm and an average thickness of 0.1 to 20 μm.