Double-coated colored mica sheet as well as preparation method and application thereof

Abstract

The invention relates to a double-coated colored mica sheet as well as a preparation method and application thereof. The double-coated colored mica sheet comprises a mica sheet substrate, a first metal simple substance coating layer coated on the mica sheet substrate, and a second rare earth metal oxide coating layer coated on the first metal simple substance coating layer. The colored mica sheet provided by the invention adopts a double-coating structure, the first coating layer is used for dyeing, the second coating layer provides a protection effect, and the obtained material has relatively good color stability and an excellent flocking imitation effect, and can be applied to the industries of automobile interior and exterior decorations, consumer electronic exterior parts, household appliance exterior parts and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of processing technologies, and particularly relates to a double-coated colored mica sheet, a preparation method thereof, and an application thereof. Background Art

[0002] The flocked effect can add excellent visual effects and endow unique aesthetic values in scenarios such as automotive interior and exterior trims, consumer electronics, and home appliance products. As a layered silicate mineral, mica flakes have excellent heat resistance and insulation properties. Using sheet mica for the flocked effect can add aesthetic effects while maintaining or even improving the material properties, thereby increasing the product value and recognition.

[0003] Colored mica generally forms a coating layer on the surface of the mica substrate with non-ferrous metal oxides to form a flocked dot material with good color. However, since the oxide layer is exposed on the surface, the material is prone to falling off during injection molding due to the melt index, screw shear, and barrel wall friction. It is challenging to prepare colored mica flocked dots through the oxide layer, and it is highly challenging to maintain non-decolorization during the injection molding process when adding the flocked effect. In addition, the coating of metal oxides also has defects in poor thermal conductivity and mechanical strength. For example, if alumina coating is used, its thermal conductivity is low (about 30 W / m·K), and the heat dissipation ability is weak, which is not suitable for scenarios that require rapid heat conduction and dissipation (injection molding). At the same time, alumina belongs to brittle ceramic materials with weak impact resistance and is prone to cracking in a shear environment (screw environment). Another example is cobalt oxide, which belongs to ceramic materials, and the coating layer is prone to cracking in a shear environment, restricting plastic processing applications and posing a toxicity risk.

[0004] CN103788719A provides a preparation method of a single-coated spinel-type chromium cobalt green-coated mica pearlescent composite pigment, which uses soluble cobalt salts and chromium salts as raw materials to prepare a single-coated chromium cobalt green-coated mica composite pigment. However, in this scheme, chromium cobalt green is coated on the mica surface at the nanoscale and is prone to shear decolorization during injection molding.

[0005] CN106009786A provides a doped high-infrared-reflecting rare earth sesquisulfide γ-Ce2S3-coated mica pearlescent pigment and a preparation method thereof. However, the coating layer uses rare earth sulfide and is not formed for the application in plastic parts.

[0006] Therefore, it is an urgent technical problem in the art to provide an inorganic pigment with excellent color stability and flocked effect and apply it to the field of plastic appearance. Summary of the Invention

[0007] To solve the above technical problems, the present invention provides a double-coated colored mica sheet, its preparation method and application. The colored mica sheet provided by the present invention adopts a double-coated structure. The first coating layer is used for dyeing, and the second coating layer provides a protective effect. The obtained material has good color stability and excellent flocked imitation effect, and can be applied to industries such as automotive interior and exterior trims, consumer electronics exterior parts, and household appliance exterior parts.

[0008] To achieve this purpose, the present invention adopts the following technical solutions:

[0009] In the first aspect, the present invention provides a double-coated colored mica sheet, which includes a mica sheet substrate, a first metal single-element coating layer coated on the mica sheet substrate, and a second rare earth metal oxide coating layer coated on the first metal single-element coating layer.

[0010] In the present invention, the first metal single-element coating layer is used for dyeing, and the second rare earth metal oxide coating layer serves as a protective layer. When the obtained material is processed by injection molding later, the protective layer will first rub against the screw and the barrel wall, thereby protecting the internal dyeing layer from being damaged and preventing decolorization. The double-coated colored mica sheet provided by the present invention has good color stability and excellent flocked imitation effect, and can be applied to industries such as automotive interior and exterior trims, consumer electronics exterior parts, and household appliance exterior parts.

[0011] Preferably, the particle size of the mica sheet substrate is 0.001 - 5.5 mm (for example, it can be 0.005 mm, 0.01 mm, 0.05 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, etc.).

[0012] Preferably, the thickness of the mica sheet substrate is 40 - 75 μm (for example, it can be 45 μm, 50 μm, 55 μm, 60 μm, 70 μm, etc.).

[0013] In the present invention, the particle size is tested by the sieving method. The mica sheet is placed on a vibrating sieve machine, and the sieves are stacked according to the decreasing aperture (such as 200 mesh, 100 mesh). The residual amount of each sieve layer is weighed, and the distribution curve is determined by the percentage of the actual amount passing through the sieve and the amount inside the sieve with different mesh numbers. The thickness is tested by the white light interference method for industrial quality inspection. The mica sheet is placed on the stage, and a flat area is selected for scanning. The mica sheet is picked up in the range of 1×1 cm, 9 times, and the average value is calculated. The software automatically extracts the thickness distribution (such as average thickness ± standard deviation).

[0014] Preferably, the metal single element in the first metal single-element coating layer includes aluminum and / or cobalt.

[0015] In the present invention, the metal element in the first metal element coating layer includes aluminum and / or cobalt, which has better heat dissipation ability compared with metal oxides, such as aluminum oxide or cobalt oxide, is more suitable for scenarios requiring rapid heat conduction and dissipation, has higher mechanical strength, can adapt to the screw environment, and has better stability.

[0016] Preferably, the thickness of the first metal element coating layer is 0.01 - 30 μm (for example, it can be 0.02 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 15 μm, 20 μm, 25 μm, etc.).

[0017] Preferably, the rare earth metal oxide in the second rare earth metal oxide coating layer includes any one or a combination of at least two of cerium trioxide, yttrium trioxide or ytterbium trioxide.

[0018] Preferably, the thickness of the second rare earth metal oxide coating layer is 10 - 30 μm (for example, it can be 12 μm, 15 μm, 18 μm, 20 μm, 22 μm, 25 μm, 28 μm, etc.).

[0019] In the present invention, if the thickness of the second rare earth metal oxide coating layer is too small, the protective layer cannot effectively play its role. When the thickness is within the above - defined range, the color stability of the material is better.

[0020] Secondly, the double - coated colored mica flakes of the present invention can be prepared by any known method in the art, such as the mechanical mixing method, but the adhesion is not strong; the physical vapor deposition method, but the conditions are harsh and large - scale preparation is difficult; the electrostatic adsorption method, but the stability is not high.

[0021] In order to strengthen the bonding force between the metal element coating layer and the rare earth metal oxide layer, and enhance the protective effect of the second rare earth metal oxide, the present invention preferably adopts the following preparation method:

[0022] (1) Mix the mica flake substrate and the metal salt, and obtain an intermediate product after heating and aging.

[0023] (2) Deposit the rare earth metal salt on the surface of the intermediate product, and obtain the double - coated colored mica flakes after calcination.

[0024] Preferably, the metal salt in step (1) includes aluminum nitrate and / or cobalt nitrate.

[0025] Preferably, the mass ratio of the mica flake substrate to the metal salt in step (1) is 1:(0.1 - 1.8) (for example, it can be 1:0.3, 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.4, 1:1.6, etc.).

[0026] Preferably, the metal salt in step (1) is added in the form of an aqueous metal salt solution.

[0027] Preferably, the concentration of the metal salt in the aqueous metal salt solution is 0.01 - 0.60 mol / L (for example, it can be 0.05 mol / L, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, etc.).

[0028] Preferably, the mixing in step (1) is carried out in an alkaline environment.

[0029] Preferably, the alkaline reagent used in the alkaline environment includes any one or a combination of at least two of sodium bicarbonate, sodium carbonate or sodium hydroxide.

[0030] Preferably, the pH of the alkaline environment is 9 - 9.5 (for example, it can be 9.1, 9.2, 9.3, 9.4, etc.).

[0031] Preferably, the temperature of the heating and aging in step (1) is 85 - 95 °C (for example, it can be 86 °C, 88 °C, 90 °C, 92 °C, 94 °C, etc.).

[0032] Preferably, the time of the heating and aging in step (1) is 0.2 - 1 h (for example, it can be 0.3 h, 0.4 h, 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h, etc.).

[0033] Preferably, the rare earth metal salt in step (2) includes any one or a combination of at least two of cerium nitrate, yttrium nitrate or ytterbium nitrate.

[0034] Preferably, the mass ratio of the mica sheet substrate in step (1) to the rare earth metal salt in step (2) is 1:(0.04 - 0.5) (for example, it can be 1:0.08, 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.45, etc.).

[0035] Preferably, the rare earth metal salt in step (2) is added in the form of an aqueous rare earth metal salt solution.

[0036] Preferably, the concentration of the rare earth metal salt in the aqueous rare earth metal salt solution is 0.01 - 0.1 mol / L (for example, it can be 0.02 mol / L, 0.04 mol / L, 0.06 mol / L, 0.08 mol / L, 0.09 mol / L, etc.).

[0037] Preferably, the deposition in step (2) is carried out in an acidic environment.

[0038] Preferably, the acidic reagent used in the acidic environment includes any one or a combination of at least two of citric acid, hydrochloric acid or boric acid.

[0039] Preferably, the pH of the acidic environment is 4.5 - 6.5 (for example, it can be 4.8, 5.0, 5.2, 5.5, 5.8, 6.0, 6.2, etc.).

[0040] Preferably, the deposition in step (2) is carried out by screen printing.

[0041] Preferably, the screen printing includes mixing a rare earth metal salt and a printing paste, and depositing the rare earth metal salt on the surface of the intermediate product by screen printing.

[0042] Preferably, the printing paste includes any one or a combination of at least two of polyphenylene oxide resin, aromatic amine or silica gel.

[0043] Preferably, the aromatic amine is diaminodiphenyl sulfone.

[0044] Preferably, the printing paste is a combination of polyphenylene oxide resin and aromatic amine.

[0045] Preferably, the mass ratio of the polyphenylene oxide resin to the aromatic amine is (8 - 12):1 (for example, it can be 8:1, 9:1, 10:1, 11:1, 12:1, etc.).

[0046] Preferably, the mass ratio of the mica sheet substrate to the printing paste is 1:(0.1 - 2) (for example, it can be 1:0.1, 1:0.5, 1:1, 1:1.5, 1:2, etc.).

[0047] Preferably, the calcination temperature in step (2) is 850 - 950 °C (for example, it can be 860 °C, 880 °C, 900 °C, 920 °C, 940 °C, etc.).

[0048] Preferably, the calcination time in step (2) is 1.5 - 2.5 h (for example, it can be 1.6 h, 1.8 h, 2 h, 2.2 h, 2.4 h, etc.).

[0049] Preferably, the calcination in step (2) is carried out in a reducing gas.

[0050] Preferably, the reducing gas includes carbon monoxide and / or hydrogen.

[0051] In the present invention, under the action of a reducing gas and high temperature, the metal salt of the first layer coating will ultimately be reduced to a metal single substance, and the rare earth metal salt of the second layer will be converted into a rare earth metal oxide. At the interface connection between the two, the metal single substance of the first layer and the rare earth metal oxide of the second layer will undergo a displacement reaction under the action of the reducing gas, generating a metal oxide and a rare earth metal single substance, thereby strengthening the bonding force between the two layers and simultaneously enhancing the protective effect of the second layer of rare earth metal oxide.

[0052] In a third aspect, the present invention provides a resin composition, which comprises the double-coated colored mica flakes as described in the first aspect.

[0053] Preferably, the resin composition comprises the following components in parts by weight:

[0054] Resin: 70 - 90 parts

[0055] The double-coated colored mica flakes as described in the first aspect: 0.1 - 1 part

[0056] Light stabilizer (2-(2H-benzotriazol-2)-4,6-bis(1-methyl-1-phenylethyl)phenol): 0 - 1 part

[0057] Impact modifier (acrylate weather and impact resistant modifier, 58% rubber content): 0 - 20 parts

[0058] Heat resistant agent (random copolymer of styrene, N-phenylmaleimide (N-PMI) and maleic anhydride): 0 - 10 parts

[0059] Primary antioxidant (octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate): 0 - 0.5 part

[0060] Secondary antioxidant (tris(2,4-di-tert-butylphenyl)phosphite): 0 - 0.5 part

[0061] Lubricant (ethylenebisstearamide): 0 - 0.5 part.

[0062] In the present invention, the resin in the resin composition can be, for example, 72 parts, 75 parts, 78 parts, 80 parts, 82 parts, 85 parts, 88 parts, etc.; the double-coated colored mica flakes as described in the first aspect can be, for example, 0.2 part, 0.3 part, 0.4 part, 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part, etc.; the light stabilizer can be, for example, 0.1 part, 0.2 part, 0.3 part, 0.4 part, 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part, etc.; the impact modifier can be, for example, 2 parts, 5 parts, 8 parts, 10 parts, 12 parts, 15 parts, 18 parts, etc.; the heat resistant agent can be, for example, 1 part, 2 parts, 5 parts, 6 parts, 8 parts, etc.; the antioxidant can be, for example, 0.1 part, 0.2 part, 0.3 part, 0.4 part, etc.; the lubricant can be, for example, 0.1 part, 0.2 part, 0.3 part, 0.4 part, etc.

[0063] Preferably, the resin comprises any one or a combination of at least two of PP resin, PVC resin or HIPS resin.

[0064] Fourthly, the present invention provides an application of the double-coated colored mica sheet according to the first aspect and the resin composition according to the third aspect in automotive interior and exterior trims, consumer electronics exterior parts, and household appliance exterior parts.

[0065] Compared with the prior art, the present invention has at least the following beneficial effects:

[0066] The colored mica sheet provided by the present invention adopts a double-coated structure. The first coating layer is used for dyeing, and the second coating layer provides a protective effect. The obtained material has good color stability and excellent flocking-like effect, and can be applied to industries such as automotive interior and exterior trims, consumer electronics exterior parts, and household appliance exterior parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 It is the color effect diagram provided by Application Example 1.

[0068] Figure 2 It is the color effect diagram provided by Application Example 2.

[0069] Figure 3 It is the color effect diagram provided by Comparative Application Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0070] The technical solutions of the present invention will be further described below with reference to the drawings and through specific embodiments. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of the protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0071] Example 1

[0072] This example provides a double-coated colored mica sheet, which includes a mica sheet substrate (particle size 0.01 mm), a first metal single-element coating layer (cobalt, thickness 1 μm) coated on the mica sheet substrate, and a second rare earth metal oxide coating layer (yttrium trioxide, thickness 15 μm) coated on the first metal single-element coating layer.

[0073] The preparation method is as follows:

[0074] (1) 1.5 g of white mica sheets are placed in 200 mL of sodium bicarbonate aqueous solution with a pH of 9, and 20 mL of Co(NO3)2 solution with a concentration of 0.05 mol / L is dropped in (that is, the mass ratio of white mica sheets to cobalt nitrate is 1:0.12). Stir and heat up to 90 °C. After aging for 0.5 h, rinse and dry. After thorough drying, spread it on the surface of the template to obtain an intermediate product;

[0075] (2) 20 mL of yttrium nitrate solution with a concentration of 0.03 mol / L was added to a citric acid aqueous solution with a pH of 6, and the mixture was thoroughly stirred and dried, and then mixed with 1.5 g of screen printing slurry (polyphenol oxide resin: 4,4'-diaminodiphenyl sulfone = 10:1), and deposited on the surface of the treated mica sheet by screen printing (i.e., the mass ratio of white mica sheet to rare earth salt was 1:0.11). After drying, the mixture was calcined at 900°C in a CO reducing atmosphere for 2 h to obtain a double-coated colored mica sheet.

[0076] Example 2

[0077] The present embodiment provides a double-coated colored mica sheet, including a mica sheet base (particle size 0.35 mm), a first metal single substance coating layer (aluminum, thickness 5 μm) coated on the mica sheet base, and a second rare earth metal oxide coating layer (cerium trioxide, thickness 20 μm) coated on the first metal single substance coating layer.

[0078] The preparation method is as follows:

[0079] (1) 1.5 g of white mica flakes were placed in 180 mL of sodium carbonate aqueous solution with a pH of 9.5, and 20 mL of Al(NO3)3 solution with a concentration of 0.30 mol / L (i.e., the mass ratio of white mica flakes to aluminum nitrate was 1:0.85) was dropped into the solution, and the mixture was stirred and heated to 90° C. After aging for 0.5 h, the mixture was rinsed and dried, and after being fully dried, the mixture was spread on the surface of a template to obtain an intermediate product;

[0080] (2) Add 20 mL of 0.05 mol / L cerium nitrate solution to hydrochloric acid at a pH of 4.5, stir thoroughly and dry, then mix with 1 g of screen printing slurry (polyphenol oxide resin: 4,4'-diaminodiphenyl sulfone = 8:1), deposit it on the surface of the treated mica sheet by screen printing (i.e., the mass ratio of white mica sheet to rare earth salt is 1:0.22), dry it, and calcine it at 900°C in a CO reducing atmosphere for 2 h to obtain a double-coated colored mica sheet.

[0081] Example 3

[0082] The present embodiment provides a double-coated colored mica sheet, including a mica sheet substrate (particle size 0.7 mm), a first metal single substance coating layer (aluminum, thickness 10 μm) coated on the mica sheet substrate, and a second rare earth metal oxide coating layer (ytterbium trioxide, thickness 28 μm) coated on the first metal single substance coating layer.

[0083] The preparation method is as follows:

[0084] (1) 1.5 g of white mica flakes were placed in 220 mL of an aqueous sodium hydroxide solution with a pH of 9.5, and 20 mL of an Al(NO3)3 solution with a concentration of 0.60 mol / L was added dropwise (i.e., the mass ratio of white mica flakes to aluminum nitrate was 1:1.70). After stirring and heating to 90 °C, aging for 0.5 h, followed by rinsing and drying. After thorough drying, it was spread on the surface of the template to obtain an intermediate product;

[0085] (2) 20 mL of a ytterbium nitrate solution with a concentration of 0.1 mol / L was added to hydrochloric acid with a pH of 4.5. After thorough stirring and drying, it was mixed with 2 g of screen printing paste (poly(phenylene oxide): 4,4'-diaminodiphenyl sulfone = 12:1). It was deposited on the surface of the treated mica flakes by screen printing (i.e., the mass ratio of white mica flakes to rare earth salt was 1:0.48). After drying, it was calcined at 900 °C for 2 h in a CO reducing atmosphere to obtain double-coated colored mica flakes.

[0086] Example 4

[0087] This example provides a double-coated colored mica flake, which is only different from Example 2 in that the thickness of the second rare earth metal oxide coating layer is 12 μm.

[0088] Example 5

[0089] This example provides a double-coated colored mica flake, which is only different from Example 2 in that the thickness of the second rare earth metal oxide coating layer is 28 μm.

[0090] Example 6

[0091] This example provides a double-coated colored mica flake, which is only different from Example 2 in that the preparation method is different:

[0092] (1) 1.5 g of white mica flakes were placed in 180 mL of an aqueous sodium carbonate solution with a pH of 9.5, and 20 mL of an Al(NO3)3 solution with a concentration of 0.30 mol / L was added dropwise (i.e., the mass ratio of white mica flakes to aluminum nitrate was 1:0.85). After stirring and heating to 90 °C, aging for 0.5 h, followed by rinsing and drying. After thorough drying, it was spread on the surface of the template to obtain an intermediate product;

[0093] (2) 20 mL of a cerium nitrate solution with a concentration of 0.05 mol / L was added to citric acid with a pH of 4.5, and water was added and stirred to form a transparent sol. The intermediate product was pretreated with a silane coupling agent (KH-550) to enhance the surface binding force. The pretreated intermediate product was immersed in the sol, and then dried at 80 °C and calcined at 500 °C for 1.5 h to form double-coated colored mica flakes.

[0094] Comparative Example 1

[0095] This comparative example provides a single-coated colored mica sheet, which is different from Example 2 in that it only includes a mica sheet substrate (particle size 0.35 mm) and an aluminum coating layer (thickness 5 μm) coated on the mica sheet substrate.

[0096] Only step (1) is carried out in the preparation method.

[0097] Comparative Example 2

[0098] This comparative example provides a double-coated colored mica sheet, which is different from Example 2 only in that the second metal oxide coating layer coated on the first metal single-element coating layer is titanium dioxide with a thickness of 20 μm.

[0099] In the preparation method, step (1) is the same as that in Example 2, and step (2) is as follows:

[0100] Disperse the intermediate product in a 0.5 mol / L tetrabutyl titanate solution, heat the mixed solution to 65 °C, and keep stirring for more than 1 h to carry out hydrolysis and polycondensation to form a sol, so that the sol can uniformly adhere to the surface of the substrate, and obtain a double-coated mica sheet with a 20-μm titanium dioxide coating on the surface after drying and calcination.

[0101] In the above examples and comparative examples, the thicknesses of the first coating layer and the second coating layer are tested on the double-coated colored mica sheet using a TEM transmission electron microscope.

[0102] Application Example 1

[0103] This application example provides a PP resin composition, which includes the following components in parts by weight:

[0104] 80 parts of PP resin (Borealis Polyolefins, grade PP EP548R)

[0105] 0.4 part of the double-coated colored mica sheet provided in Example 1

[0106] 0.5 part of a light stabilizer (Suqian Liansheng Technology Co., Ltd., grade UV-234, 2-(2H-benzotriazol-2)-4,6-bis(1-methyl-1-phenylethyl)phenol)

[0107] 5 parts of an impact modifier (Anqiu Donghai Plastics Co., Ltd., grade Q500, an acrylate weather-resistant impact modifier with a rubber content of 58%, which is a graft copolymer with polyacrylate rubber as the core and methyl methacrylate-acrylonitrile-styrene (MMA-AN-St) as the shell)

[0108] 2 parts of a heat-resistant agent (Jiaxing Huawei Chemical Co., Ltd., grade HW-320, a random copolymer of styrene, N-phenylmaleimide (N-PMI) and maleic anhydride)

[0109] 0.2 parts of the primary antioxidant (Tianjin LiAnLong New Materials Co., Ltd., product number RIANOX 1076, octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate)

[0110] 0.2 parts of the secondary antioxidant (Tianjin LiAnLong New Materials Co., Ltd., product number RIANOX 168, tris(2,4-di-tert-butylphenyl) phosphite)

[0111] 0.1 part of the lubricant (Guangzhou RunFeng Technology Co., Ltd., product number EBS B50, ethylene bisstearamide).

[0112] The preparation method of the PP resin composition includes: mixing the components of the PP resin composition except the double-coated colored mica flakes, feeding the mixture as the main feed, and feeding the double-coated colored mica flakes laterally, and extruding and molding with a twin-screw extruder to obtain finished pellets, and the extrusion temperature is 200 °C.

[0113] Application Examples 2-6, Comparative Application Examples 1-2

[0114] The difference between the above application examples, comparative application examples and Application Example 1 is only that the double-coated colored mica flakes provided in Example 1 are respectively replaced with the colored mica flakes provided in Examples 2-6 and Comparative Examples 1-2, and the preparation method refers to Application Example 1.

[0115] Test the color value and color stability of the PP resin composition provided in the above application examples. The test method is as follows:

[0116] (1) Color value: According to the test standard ASTM D2244-2015, use a spectrophotometer to test the L, a, b values of the sample.

[0117] (2) Stability: Keep the PP resin composition at 210 °C for 5 min in a plastic injection molding machine, and take the previous mold before the 210 °C heat retention for 5 min and the next mold after the 210 °C heat retention for 5 min respectively for color thermal stability comparison, and calculate the color difference through the following formula

[0118]

[0119] Where represents the value of the sample before the aging treatment, represents the value of the sample after the aging treatment.

[0120] For the present invention, the vividness mainly depends on the a, b values, that is, the green phase and the blue phase. Generally speaking, the smaller the a value and the smaller the b value, the greener and bluer the color, and the more vivid.

[0121] The test results are shown in Table 1. Exemplarily, the color effect diagrams of the PP resin compositions provided by Application Example 1, Application Example 2, and Comparative Application Example 1 are as Figure 1 , Figure 2 , Figure 3 shown.

[0122] Table 1

[0123]

[0124]

[0125] It can be seen from the test results that when the double-coated colored mica flakes provided by Embodiments 1-6 of the present invention are applied to the PP resin material, the obtained material has excellent flocking-like effect, bright color, and good stability. Specifically, the L value is greater than 60, the a value is less than -1, the b value is less than 6, less than 2.

[0126] It can be seen from the comparison between Application Example 2 and Application Example 4 that when the thickness of the rare earth element coating layer is too small, the thermal stability of the material is poor, greater than 1.5.

[0127] It can be seen from the comparison between Application Example 2 and Application Example 5 that when the thickness of the rare earth element coating layer is too large, the change in the thermal stability of the material is not significant, but the brightness of the material itself will decrease.

[0128] It can be seen from the comparison between Application Example 2 and Comparative Application Example 1 that when there is no rare earth element coating layer, the brightness of the material color will be damaged, and it will be significantly darker, redder and yellower, and the color stability becomes worse.

[0129] It can be seen from the comparison between Application Example 2 and Comparative Application Example 2 that when a titanium dioxide coating layer is used, its heat resistance becomes poor, increases.

[0130] The applicant declares that the above description is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A double-coated colored mica sheet, characterized in that: The double-coated colored mica sheet comprises a mica sheet substrate, a first metal single substance coating layer coated on the mica sheet substrate, and a second rare earth metal oxide coating layer coated on the first metal single substance coating layer.

2. The double-coated colored mica sheet according to claim 1, characterized in that: The particle size of the mica sheet substrate is 0.001-5.5 mm.

3. The double-coated colored mica sheet according to claim 1, characterized in that: The metal element in the first metal element coating layer includes aluminum and / or cobalt; Preferably, the thickness of the first metal single substance coating layer is 0.01-30 μm.

4. The double-coated colored mica sheet according to claim 1, characterized in that: The rare earth metal oxide in the second rare earth metal oxide coating layer includes any one of cerium trioxide, yttrium trioxide or ytterbium trioxide, or a combination of at least two thereof; Preferably, the second rare earth metal oxide coating layer has a thickness of 10-30 μm.

5. A method for preparing the double-coated colored mica sheet according to any one of claims 1 to 4, characterized in that: The preparation method comprises the following steps: (1) mixing a mica flake substrate and a metal salt, heating and aging the mixture to obtain an intermediate product; (2) depositing rare earth metal salt on the surface of the intermediate product, and obtaining the double-coated colored mica sheet after calcination.

6. The preparation method according to claim 5, characterized in that: The metal salt in step (1) comprises aluminum nitrate and / or cobalt nitrate; Preferably, the mass ratio of the mica flake substrate to the metal salt in step (1) is 1:(0.1-1.8); Preferably, the metal salt in step (1) is added in the form of a metal salt aqueous solution; Preferably, the concentration of the metal salt in the metal salt aqueous solution is 0.01-0.60 mol / L; Preferably, the mixing in step (1) is performed under an alkaline environment; Preferably, the alkaline agent used in the alkaline environment includes any one of sodium bicarbonate, sodium carbonate or sodium hydroxide, or a combination of at least two thereof; Preferably, the pH of the alkaline environment is 9-9.5; Preferably, the heating and aging temperature in step (1) is 85-95°C; Preferably, the heating and aging time in step (1) is 0.2-1h.

7. The preparation method according to claim 5, characterized in that: The rare earth metal salt in step (2) includes any one of cerium nitrate, yttrium nitrate or ytterbium nitrate, or a combination of at least two thereof; Preferably, the mass ratio of the mica sheet substrate in step (1) to the rare earth metal salt in step (2) is 1:(0.04-0.5); Preferably, the rare earth metal salt in step (2) is added in the form of a rare earth metal salt aqueous solution; Preferably, the concentration of the rare earth metal salt in the rare earth metal salt aqueous solution is 0.01-0.1 mol / L; Preferably, the deposition in step (2) is performed in an acidic environment; Preferably, the acidic agent used in the acidic environment includes any one of citric acid, hydrochloric acid or boric acid, or a combination of at least two thereof; Preferably, the pH of the acidic environment is 4.5-6.5; Preferably, the deposition in step (2) is performed by screen printing; Preferably, the screen printing comprises mixing a rare earth metal salt and a printing paste, and depositing the rare earth metal salt on the surface of the intermediate product by screen printing; Preferably, the printing paste comprises any one or a combination of at least two of polyphenol oxide resin, aromatic amine or silica gel; Preferably, the aromatic amine is diaminodiphenyl sulfone; Preferably, the calcination temperature in step (2) is 850-950°C; Preferably, the calcination time in step (2) is 1.5-2.5h; Preferably, the calcination in step (2) is carried out in a reducing gas; Preferably, the reducing gas comprises carbon monoxide and / or hydrogen.

8. A resin composition, characterized in that The resin composition comprises the double-coated colored mica sheet as described in any one of claims 1 to 4.

9. The resin composition according to claim 8, characterized in that The resin composition comprises the following components in parts by weight: Resin 70-90 parts 0.1-1 part of the double-coated colored mica sheet according to any one of claims 1-4 Light stabilizer 0-1 part Anti-impact agent 0-20 parts Heat resistant agent 0-10 parts Antioxidant 0-0.5 parts Lubricant 0-0.5 parts.

10. Use of the double-coated colored mica sheet according to any one of claims 1 to 4 and the resin composition according to claim 8 or 9 in automobile interior and exterior decoration, consumer electronic appearance parts, and household appliance appearance parts.

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