Red pearlescent pigment as well as preparation method and application thereof

Abstract

The invention discloses a red pearlescent pigment as well as a preparation method and application thereof, and relates to the technical field of automobile coatings. The red pearlescent pigment comprises a laminated oxide film which is alternately prepared from silicon dioxide and titanium dioxide; a starting film layer and a terminating film layer of the laminated oxide film are silicon dioxide films; the number of layers of the laminated oxide films is 5-13. The prepared red pearlescent pigment has no shielding effect on millimeter wave radar, can meet the requirements of an automatic driving technology, and has the characteristics of high flickering feeling and high covering power. When the red pearlescent pigment is prepared by adopting a physical vapor deposition method, no three wastes are generated in the production process, the process is environment-friendly, the pigment performance of the prepared product is superior to that of a red pearlescent product prepared by a traditional process, and the red pearlescent pigment is expected to be popularized and applied in the field of automobile coatings.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile coatings, and in particular to a red pearlescent pigment and a preparation method and application thereof. Background Art

[0002] With the advancement of autonomous driving technology, the importance of perception systems, as a core component for safe driving, has become increasingly prominent. Perception systems typically consist of multiple sensors, including cameras, millimeter-wave radar, and lidar. Lidar, due to its high-precision environmental modeling capabilities, is typically mounted on the vehicle's roof, while millimeter-wave radar is located inside the vehicle's front and rear bumpers to monitor dynamic information about the surrounding environment in real time. This multi-sensor fusion solution aims to improve the accuracy and reliability of the perception system, thereby providing safer environmental perception capabilities for autonomous driving.

[0003] In automotive exterior design, coatings not only fulfill aesthetic and protective functions but also need to be compatible with the vehicle's technical requirements. Red aluminum-based pigments, due to their vibrant color, excellent hiding power, and striking sparkle, are a key component in enhancing the vehicle's exterior quality and are widely used in automotive coatings. However, when used in bumper paint, red aluminum-based pigments often significantly shield millimeter-wave signals, interfering with the proper functioning of millimeter-wave radar and, in turn, impacting the performance of the sensing system.

[0004] To address this issue, pearlescent pigments have been introduced as a potential alternative in automotive coatings. They offer no shielding effect on millimeter-wave signals and can meet the operational requirements of millimeter-wave radar. However, the hiding power and sparkle of traditional red pearlescent pigments are significantly lower than those of red aluminum-based pigments. Furthermore, pearlescent pigments produced using traditional processes struggle to achieve both high transmittance for millimeter-wave signals and high sparkle and hiding power. Therefore, maintaining the aesthetics and functionality of automotive coatings while meeting the performance requirements of millimeter-wave radar has become a major challenge facing the automotive coatings industry.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The purpose of the present invention is to provide a red pearlescent pigment and a preparation method and application thereof, so as to solve the above technical problems.

[0007] The present invention is achieved in that:

[0008] In a first aspect, an embodiment of the present invention provides a red pearlescent pigment comprising a stacked oxide film prepared alternately with silicon dioxide and titanium dioxide;

[0009] Wherein, the starting film layer and the ending film layer of the stacked oxide film are silicon dioxide films;

[0010] The number of film layers of the stacked oxide film is 5 to 13 layers.

[0011] In a second aspect, an embodiment of the present invention provides a method for preparing the aforementioned red pearlescent pigment, comprising the following preparation steps:

[0012] A silicon dioxide film is deposited on the surface of the substrate as a starting film layer by using a physical vapor deposition method;

[0013] A titanium dioxide film and a silicon dioxide film are alternately plated on the starting film layer, and after the number of plated layers is reached and the silicon dioxide film is used as the termination film layer, the plated film is stopped to obtain a laminated oxide film;

[0014] After the laminated oxide film is demoulded, a red pearlescent pigment is obtained.

[0015] In a third aspect, an embodiment of the present invention provides an automotive coating, which includes the aforementioned red pearlescent pigment or the red pearlescent pigment prepared by the aforementioned preparation method.

[0016] The present invention has the following beneficial effects:

[0017] The red pearlescent pigment produced by the physical vapor deposition method in this embodiment of the present invention generates no waste, waste gas, or other wastes, making the process environmentally friendly. The resulting product performs better than red pearlescent products produced by traditional methods. The red pearlescent pigment has no shielding effect on millimeter-wave radar, meeting the requirements of autonomous driving technology. It also exhibits high scintillation and hiding power, promising widespread application in the automotive coatings industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 Schematic diagram of the cross-sectional structure of the red pearlescent pigment with 5 and 7 layers;

[0020] Figure 2 Schematic diagram of the cross-sectional structure of the red pearlescent pigment with 9 and 11 layers;

[0021] Figure 3 This is a schematic diagram of the cross-sectional structure when the red pearlescent pigment has 13 layers;

[0022] Figure 4 This is a graph showing the reflectivity test results of the red pearlescent pigment prepared in Example 1;

[0023] Figure 5 This is a graph showing the reflectivity test results of the red pearlescent pigment prepared in Example 2;

[0024] Figure 6 This is a graph showing the reflectivity test results of the red pearlescent pigment prepared in Example 3;

[0025] Figure 7 This is a graph showing the reflectivity test results of the red pearlescent pigment prepared in Example 4;

[0026] Figure 8 This is a graph showing the reflectivity test results of the red pearlescent pigment prepared in Example 5;

[0027] Figure 9 This is a graph showing the reflectivity test results of the red pearlescent pigment prepared in Example 6;

[0028] Figure 10 This is a graph showing the reflectivity test results of the red pearlescent pigment prepared in Example 7;

[0029] Figure 11 This is a graph showing the reflectivity test results of the red pearlescent pigment prepared in Example 8;

[0030] Figure 12 This is a graph showing the reflectivity test results of the red pearlescent pigment prepared in Comparative Example 1. DETAILED DESCRIPTION

[0031] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased commercially.

[0032] Pearlescent pigments improve the accuracy and reliability of sensing systems, thereby providing safer environmental perception capabilities for autonomous driving. This invention uses physical vapor deposition to produce a red pearlescent pigment that meets the performance requirements of millimeter-wave radar while maintaining the aesthetics and functionality of automotive coatings. The specific implementation process is as follows:

[0033] In a first aspect, an embodiment of the present invention provides a red pearlescent pigment comprising a stacked oxide film prepared alternately with silicon dioxide and titanium dioxide;

[0034] Wherein, the starting film layer and the ending film layer of the stacked oxide film are silicon dioxide films;

[0035] The number of film layers of the stacked oxide film is 5 to 13 layers.

[0036] It should be noted that the following characteristics of silicon dioxide make it suitable for use as the outer layer of pearlescent pigments, such as softening the gloss and enhancing the color level; blocking photocatalysis and enhancing durability; being compatible with high-tech requirements such as millimeter-wave radar; and meeting safety and environmental regulations. Although titanium dioxide can provide high reflectivity and bright colors, due to its photocatalytic activity, dielectric loss, poor dispersibility and other problems, it usually needs to be coated with silicon dioxide to optimize its performance. If titanium dioxide is used directly as the outer layer, additional treatment (such as surface passivation) is required to suppress photocatalysis, and the preparation cost is higher.

[0037] Silicon dioxide is a low-refractive-index material, while titanium dioxide is a high-refractive-index material. The combination of these two enhances the multilayer interference effect and heightens the layered texture of the pearlescent luster. Furthermore, by controlling the thickness of the TiO2 film, its angle-dependent color change can be precisely controlled. Titanium dioxide provides high reflectivity and color intensity, while silicon dioxide imparts wave transparency, dispersibility, and structural stability. This combination of the two allows red pearlescent pigments to simultaneously meet aesthetic, functional, and environmental requirements.

[0038] The number of film layers of the laminated oxide film can be selected from any one of 5 layers, 7 layers, 9 layers, 11 layers and 13 layers according to actual needs. Since the silicon dioxide layer is used as the starting layer and the ending layer, the number of layers of the prepared laminated oxide film is an odd number.

[0039] It should be noted that the thickness of the laminated oxide film will directly affect the optical path difference and interference conditions; when the number of film layers and the thickness of the film layers are within the set range, the red pearlescent pigment produced can meet the performance requirements of millimeter-wave radar; if the number of film layers is too small (such as 5 layers), the reflectivity of the pigment is not high enough, the color concentration is poor, and it cannot fully meet the application requirements; when the number of coating layers gradually increases from 5 layers to 11 layers, the reflectivity of the pigment increases significantly and the color concentration is enhanced; but after the coating reaches 11 layers, continuing to increase the number of film layers (such as 13 layers) can no longer significantly increase the reflectivity of red light, and the film layer is too thick, the diameter thickness of the pigment produced is poor, and it is easy to settle and agglomerate in the coating.

[0040] In an optional embodiment of the present invention, the thickness of the starting film layer and the thickness of the ending film layer are independently 10 nm-80 nm.

[0041] It should be noted that in an optional embodiment of the present invention, the thickness of the starting film layer and the thickness of the ending film layer are the same, and can be selected from any one of 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, and 80nm, or other values within the range of 10nm-80nm. In other embodiments of the present invention, the thickness of the starting film layer and the thickness of the ending film layer can also be set to different values, which can be reasonably adjusted according to actual needs.

[0042] In an optional embodiment of the present invention, in the intermediate film layer, the thickness of each silicon dioxide film layer is independently 110 nm-150 nm.

[0043] It should be noted that in an optional embodiment of the present invention, the thickness of each silicon dioxide film layer in the intermediate film layer is the same, and can be selected from any one of 110 nm, 115 nm, 130 nm, 145 nm, and 150 nm, or other values within the range of 110 nm to 150 nm. In other embodiments of the present invention, the thickness of each silicon dioxide film layer in the intermediate film layer can also be set to different values, which can be reasonably adjusted according to actual needs.

[0044] In an optional embodiment of the present invention, in the intermediate film layer, the thickness of each titanium dioxide film layer is independently 60 nm-100 nm.

[0045] It should be noted that in an optional embodiment of the present invention, the thickness of each titanium dioxide film layer in the intermediate film layer can be selected from any one of 60nm, 65nm, 80nm, 95nm, and 100nm, or other values within the range of 60nm-100nm. In other embodiments of the present invention, the thickness of each titanium dioxide film layer in the intermediate film layer can also be set to different values, which can be reasonably adjusted according to actual needs.

[0046] It should be noted that in the intermediate film layer, if the thickness of each silicon dioxide film layer and the thickness of each titanium dioxide film layer are set to be the same, it is beneficial to enhance the reflection of light of similar wavelengths, making the color of the pigment purer and more vivid; if the thickness of the film layers are different, the reflected light may be disordered, causing mixed colors to be mixed in the pigment.

[0047] In a second aspect, an embodiment of the present invention provides a method for preparing the aforementioned red pearlescent pigment, comprising the following preparation steps:

[0048] A silicon dioxide film is deposited on the surface of the substrate as a starting film layer by using a physical vapor deposition method;

[0049] A titanium dioxide film and a silicon dioxide film are alternately plated on the starting film layer, and after the number of plated layers is reached and the silicon dioxide film is used as the termination film layer, the plated film is stopped to obtain a laminated oxide film;

[0050] After the laminated oxide film is demoulded, a red pearlescent pigment is obtained.

[0051] It should be noted that physical vapor deposition (PVD) is a technique that converts solid materials into a vapor state through physical methods (such as evaporation, sputtering, or ion plating) in a vacuum environment, and then deposits the vapor onto the substrate surface to form a thin film. This evaporation technique has the following characteristics: high film deposition precision; being carried out in a vacuum environment effectively avoids contamination, resulting in high-purity films; and the ability to deposit nanometer-thick films and complex multilayer films.

[0052] The present invention does not impose any particular restrictions on the equipment used for coating, and the equipment may be selected appropriately based on actual needs. In an optional embodiment of the present invention, an electron beam evaporation coating machine is used as the film-forming equipment during the preparation of the pearlescent pigment. In other embodiments of the present invention, the equipment may be appropriately replaced based on actual needs.

[0053] It should be noted that after the release treatment, the laminated oxide film is crushed, graded, and screened to produce red pearlescent pigments with similar colors but different particle sizes. The crushed, graded, and screened red pearlescent pigments have a particle size range of 200-1000 mesh. Depending on the application area of the red pearlescent pigment, its color and particle size will vary accordingly, and the specific particle size needs to be adjusted appropriately based on the actual situation. For example, automotive paints are commonly used with a particle size range of 400-800 mesh.

[0054] In an optional embodiment of the present invention, during the coating process, the coating rate of each film layer is independently selected from 0.5 nm / s to 4 nm / s. It can be selected from any one of 0.5 nm / s, 1 nm / s, 2 nm / s, 3 nm / s, and 2 nm / s according to actual needs, or can be selected from other values within the range of 0.5 nm / s to 4 nm / s.

[0055] It's important to note that the coating rate determines the amount of material deposited on the substrate surface per unit time. The higher the rate, the thicker the film deposited in the same amount of time; conversely, the lower the rate, the thinner the film deposited. Therefore, by controlling the coating rate, the film thickness can be precisely controlled. Excessively fast deposition rates can increase internal stress in the coating layer, reducing adhesion between the coating and the substrate. Properly controlling the deposition rate can reduce internal stress and improve the bond strength between the coating and the substrate. Furthermore, excessively fast deposition rates can prevent atoms from fully diffusing and aligning on the surface, resulting in a porous, rough coating layer and reduced coating quality and uniformity. Properly reducing the deposition rate allows atoms sufficient time to migrate to their lowest energy positions, forming a uniform, dense coating layer.

[0056] In an optional embodiment of the present invention, an oxidizing gas is introduced during the titanium dioxide coating process; the oxidizing gas is selected from at least one of oxygen and ozone.

[0057] It should be noted that when TiO2 is heated and evaporated in a vacuum, it decomposes and loses oxygen, forming a highly absorbent titanium suboxide film. To obtain a pure TiO2 film, an oxidizing gas must be introduced during the coating process. Before coating the titanium dioxide film, the vacuum chamber must be evacuated. Once the vacuum reaches a predetermined value, the oxidizing gas is introduced. Ensure that no residual gas or liquid remains in the vacuum chamber to avoid affecting the coating effect. During the coating process, the oxidizing gas is continuously and steadily introduced. The oxidizing gas flow rate and pressure are adjusted according to the coating requirements and actual conditions. At the same time, the reaction within the vacuum chamber is closely monitored to ensure the production of a pure TiO2 film.

[0058] The type and amount of the oxidizing gas used can be adjusted according to actual needs. For example, when the gas is oxygen, the gas flow rate is 1.0×10 -2 Pa·m 3 ·s -1 to 8.0×10 -2 Pa·m 3 ·s -1 After oxygen is passed through, the vacuum chamber pressure is 1.0×10 -3 Pa to 3.0×10 -3 Pa.

[0059] In an optional embodiment of the present invention, the material of the substrate is selected from any one of stainless steel, glass, plastic, and resin.

[0060] It should be noted that the material of the substrate does not affect the preparation of the laminated oxide film; it only needs to facilitate the removal of the laminated oxide film. A hard, bendable, or foldable material can be selected according to actual needs. For example, when using a stainless steel substrate, after the coating is completed, the substrate and the laminated oxide film can be bent together to achieve demolding. When using a glass substrate, the glass substrate and the laminated oxide film can be heated to 200°C and then quickly immersed in cold water to achieve demolding.

[0061] In an optional embodiment of the present invention, the substrate is further cleaned with anhydrous ethanol, acetone, and water before coating.

[0062] It should be noted that thorough cleaning of the substrate is crucial. If there are contaminants on the surface of the substrate, it will seriously affect the uniformity, adhesion and corrosion resistance of the film layer. In addition, the presence of contaminants will cause problems such as blistering and falling off of the film layer, thereby affecting the appearance and function of the product.

[0063] In summary, the method for preparing the red pearlescent pigment in the embodiment of the present invention specifically comprises the following steps:

[0064] An electron beam evaporation coating machine is used as the film forming equipment, and a layer of silicon dioxide film is coated on the surface of the substrate as the starting film layer by physical vapor deposition. The coating rate is 0.5nm / s-4nm / s, and the thickness of the film layer is 10nm-80nm.

[0065] Titanium dioxide film and silicon dioxide film are alternately plated on the starting film layer in sequence. When the number of plated layers is reached and the silicon dioxide film is used as the termination film layer, the plated film is stopped to obtain a laminated oxide film.

[0066] It should be noted that the coating rate of the intermediate film layer is 0.5nm / s-4nm / s, the thickness of each titanium dioxide film in the intermediate film layer is the same, which is 60nm-100nm, and oxygen is introduced into the equipment during the preparation of the titanium dioxide film; the thickness of each silicon dioxide film is the same, which is 110nm-150nm; when the silicon dioxide film is the termination film layer, the coating rate is 0.5nm / s-4nm / s, and the thickness of the film layer is the same as the thickness of the starting film layer, which is 10nm-80nm.

[0067] After demoulding, the laminated oxide film is crushed, classified and sieved to obtain a red pearlescent pigment with a mesh size of 200 to 1000.

[0068] In a third aspect, an embodiment of the present invention provides an automotive coating, which includes the aforementioned red pearlescent pigment or the red pearlescent pigment prepared by the aforementioned preparation method.

[0069] The features and performance of the present invention are further described in detail below with reference to the embodiments.

[0070] Example 1

[0071] This embodiment provides a red pearlescent pigment, the preparation method of which includes the following steps:

[0072] S1. Clean the stainless steel substrate with anhydrous ethanol, acetone, and water in sequence. Set aside after cleaning.

[0073] A silicon dioxide film is deposited on the surface of the stainless steel substrate as a starting film layer at a deposition rate of 0.5 nm / s and a film thickness of 45 nm. This film layer is recorded as S1 film.

[0074] S2. A titanium dioxide film was deposited on the S1 film obtained in step S1. Oxygen was introduced during the deposition process. The amount of oxygen introduced was 4.0×10 -2 Pa·m 3 ·s -1 The coating rate is 0.5nm / s, the film thickness is 75nm, and the film layer is recorded as T1 film.

[0075] S3. A layer of silicon dioxide film is deposited on the T1 film obtained in step S2 at a deposition rate of 0.5 nm / s and a film thickness of 115 nm. This film layer is recorded as S2 film.

[0076] S4. A titanium dioxide film is deposited on the S2 film obtained in step S3. Oxygen is introduced during the deposition process. The deposition rate is 0.5 nm / s and the film thickness is 75 nm. This film layer is recorded as T2 film.

[0077] S5. A layer of silicon dioxide film is deposited on the T2 film obtained in step S4 at a deposition rate of 0.5 nm / s and a film thickness of 115 nm. This film layer is recorded as S3 film.

[0078] S6. A titanium dioxide film is deposited on the S3 film obtained in step S5. Oxygen is introduced during the deposition process. The deposition rate is 0.5 nm / s and the film thickness is 75 nm. This film layer is recorded as T3 film.

[0079] S7. A layer of silicon dioxide film is deposited on the T3 film obtained in step S6 at a deposition rate of 0.5 nm / s and a film thickness of 115 nm. This film layer is recorded as S4 film.

[0080] S8. A titanium dioxide film is deposited on the S4 film obtained in step S7. Oxygen is introduced during the deposition process. The deposition rate is 0.5 nm / s and the film thickness is 75 nm. This film layer is recorded as T4 film.

[0081] S9. A layer of silicon dioxide film is deposited on the T4 film obtained in step S8 at a deposition rate of 0.5 nm / s and a film thickness of 115 nm. This film layer is recorded as S5 film.

[0082] S10. A titanium dioxide film is deposited on the S5 film obtained in step S9. Oxygen is introduced during the deposition process. The deposition rate is 0.5 nm / s and the film thickness is 75 nm. This film layer is recorded as T5 film.

[0083] S11. A layer of silicon dioxide film is deposited on the T5 film obtained in step S10 at a deposition rate of 0.5 nm / s and a film thickness of 115 nm. This film layer is recorded as S6 film.

[0084] S12. A titanium dioxide film is deposited on the S6 film obtained in step S11. Oxygen is introduced during the deposition process. The deposition rate is 0.5 nm / s and the film thickness is 75 nm. This film layer is recorded as a T6 film.

[0085] S13. A layer of silicon dioxide film is deposited on the T6 film obtained in step S12 at a deposition rate of 0.5 nm / s and a film thickness of 45 nm. This film layer is recorded as S7 film.

[0086] S14. Remove the stainless steel test piece and bend it to remove the film.

[0087] S15. Grind and crush the obtained film layer fragments, classify, and sieve to obtain a red pearlescent pigment with 13 film layers.

[0088] Example 2

[0089] This embodiment provides a red pearlescent pigment, and its preparation method differs from that of Example 1 only in that:

[0090] Step S11 and step S12 are omitted, and the number of film layers of the final red pearlescent pigment is 11.

[0091] Example 3

[0092] This embodiment provides a red pearlescent pigment, and its preparation method differs from that of Example 1 only in that:

[0093] Steps S9, S10, S11 and S12 are omitted, and the number of film layers of the final red pearlescent pigment is 9.

[0094] Example 4

[0095] This embodiment provides a red pearlescent pigment, and its preparation method differs from that of Example 1 only in that:

[0096] Steps S7, S8, S9, S10, S11 and S12 are omitted, and the number of film layers of the final red pearlescent pigment is 7.

[0097] Example 5

[0098] This embodiment provides a red pearlescent pigment, and its preparation method differs from that of Example 1 only in that:

[0099] Steps S5, S6, S7, S8, S9, S10, S11 and S12 are omitted, and the number of film layers of the final red pearlescent pigment is 5.

[0100] Example 6

[0101] This embodiment provides a red pearlescent pigment, the preparation method of which includes the following steps:

[0102] S1. Clean the glass substrate with anhydrous ethanol, acetone, and water in sequence, and set aside after cleaning;

[0103] A silicon dioxide film is deposited on the surface of a glass substrate as a starting film layer at a deposition rate of 1 nm / s and a film thickness of 20 nm. This film layer is recorded as S1 film.

[0104] S2. A titanium dioxide film is deposited on the S1 film obtained in step S1. Oxygen is introduced during the deposition process. The deposition rate is 0.5 nm / s and the film thickness is 75 nm. This film layer is recorded as T1 film.

[0105] S3. A layer of silicon dioxide film is deposited on the T1 film obtained in step S2 at a deposition rate of 1 nm / s and a film thickness of 115 nm. This film layer is recorded as S2 film.

[0106] S4. A titanium dioxide film is deposited on the S2 film obtained in step S3. Oxygen is introduced during the deposition process. The deposition rate is 0.5 nm / s and the film thickness is 75 nm. This film layer is recorded as T2 film.

[0107] S5. A layer of silicon dioxide film is deposited on the T2 film obtained in step S4 at a deposition rate of 1 nm / s and a film thickness of 115 nm. This film layer is recorded as S3 film.

[0108] S6. A titanium dioxide film is deposited on the S3 film obtained in step S5. Oxygen is introduced during the deposition process. The deposition rate is 0.5 nm / s and the film thickness is 75 nm. This film layer is recorded as T3 film.

[0109] S7. A layer of silicon dioxide film is deposited on the T3 film obtained in step S6 at a deposition rate of 0.5 nm / s and a film thickness of 70 nm. This film layer is recorded as S4 film.

[0110] S8. Remove the glass test piece, heat it to 200°C, and then quickly immerse it in cold water to remove the film.

[0111] S9. Grind and crush the obtained film layer fragments, classify, and sieve to obtain a red pearlescent pigment with 7 film layers.

[0112] Example 7

[0113] This embodiment provides a red pearlescent pigment, the preparation method of which includes the following steps:

[0114] S1. Clean the glass substrate with anhydrous ethanol, acetone, and water in sequence, and set aside after cleaning;

[0115] A silicon dioxide film is deposited on the surface of a glass substrate as a starting film layer at a deposition rate of 1 nm / s and a film thickness of 45 nm. This film layer is recorded as S1 film.

[0116] S2. A titanium dioxide film is deposited on the S1 film obtained in step S1. Oxygen is introduced during the deposition process. The deposition rate is 0.5 nm / s and the film thickness is 60 nm. This film layer is recorded as T1 film.

[0117] S3. A layer of silicon dioxide film is deposited on the T1 film obtained in step S2 at a deposition rate of 1 nm / s and a film thickness of 115 nm. This film layer is recorded as S2 film.

[0118] S4. A titanium dioxide film is deposited on the S2 film obtained in step S3. Oxygen is introduced during the deposition process. The deposition rate is 0.5 nm / s and the film thickness is 70 nm. This film layer is designated as T2 film.

[0119] S5. A layer of silicon dioxide film is deposited on the T2 film obtained in step S4 at a deposition rate of 1 nm / s and a film thickness of 115 nm. This film layer is recorded as S3 film.

[0120] S6. A titanium dioxide film is deposited on the S3 film obtained in step S5. Oxygen is introduced during the deposition process. The deposition rate is 0.5 nm / s and the film thickness is 80 nm. This film layer is recorded as T3 film.

[0121] S7. A layer of silicon dioxide film is deposited on the T3 film obtained in step S6 at a deposition rate of 0.5 nm / s and a film thickness of 45 nm. This film layer is recorded as S4 film.

[0122] S8. Remove the glass test piece, heat it to 200°C, and then quickly immerse it in cold water to remove the film.

[0123] S9. Grind and crush the obtained film layer fragments, classify, and sieve to obtain a red pearlescent pigment with 7 film layers.

[0124] Example 8

[0125] This embodiment provides a red pearlescent pigment, the preparation method of which includes the following steps:

[0126] S1. Clean the glass substrate with anhydrous ethanol, acetone, and water in sequence, and set aside after cleaning;

[0127] A silicon dioxide film is deposited on the surface of a glass substrate as a starting film layer at a deposition rate of 1 nm / s and a film thickness of 45 nm. This film layer is recorded as S1 film.

[0128] S2. A titanium dioxide film is deposited on the S1 film obtained in step S1. Oxygen is introduced during the deposition process. The deposition rate is 0.5 nm / s and the film thickness is 75 nm. This film layer is recorded as T1 film.

[0129] S3. A layer of silicon dioxide film is deposited on the T1 film obtained in step S2 at a deposition rate of 1 nm / s and a film thickness of 100 nm. This film layer is recorded as S2 film.

[0130] S4. A titanium dioxide film is deposited on the S2 film obtained in step S3. Oxygen is introduced during the deposition process. The deposition rate is 0.5 nm / s and the film thickness is 75 nm. This film layer is recorded as T2 film.

[0131] S5. A layer of silicon dioxide film is deposited on the T2 film obtained in step S4 at a deposition rate of 1 nm / s and a film thickness of 130 nm. This film layer is recorded as S3 film.

[0132] S6. A titanium dioxide film is deposited on the S3 film obtained in step S5. Oxygen is introduced during the deposition process. The deposition rate is 0.5 nm / s and the film thickness is 75 nm. This film layer is recorded as T3 film.

[0133] S7. A layer of silicon dioxide film is deposited on the T3 film obtained in step S6 at a deposition rate of 0.5 nm / s and a film thickness of 45 nm. This film layer is recorded as S4 film.

[0134] S8. Remove the glass test piece, heat it to 200°C, and then quickly immerse it in cold water to remove the film.

[0135] S9. Grind and crush the obtained film layer fragments, classify, and sieve to obtain a red pearlescent pigment with 7 film layers.

[0136] Comparative Example 1

[0137] This comparative example provides a common red pearlescent pigment, the preparation method of which comprises the following steps:

[0138] Titanium dioxide is coated on the surface of synthetic mica by liquid phase hydrolysis, and the thickness of the titanium dioxide layer is controlled to be about 100nm.

[0139] Test Example 1

[0140] This test example tests the reflectivity performance of the red pearlescent pigments prepared in Examples 1 to 8 and the ordinary red pearlescent pigment prepared in Comparative Example 1. The specific test method is as follows: add the pigment to the PU resin at a ratio of 10%, mix thoroughly, and use a wet film preparation device to prepare a 150 μm wet film on a glass plate. After complete drying, the test sample is obtained. The optical reflectivity test is performed using a visible light spectrophotometer, with the coating side facing the direction of the test light source. It should be noted that the test data listed in the present invention is only for comparing the effects of different embodiments, and is not used to limit the technical protection scope of the present invention. The relevant test results of the reflectivity performance tests of Examples 1 to 8 are shown in FIG. Figure 4-11 , the relevant test results of comparative example 1 are shown in Figure 12 .

[0141] Combine Figure 4-Figure 8 From the reflectivity test result graphs of (Example 1-Example 5), it can be concluded that when the number of coating layers gradually increases from 5 to 9 layers, the reflectivity of the pigment in the red light band (610nm-760nm) increases significantly, and the color concentration is enhanced; but after the coating layer reaches 9 layers, continuing to increase the number of film layers to 11 or 13 layers can no longer significantly increase the reflectivity of red light.

[0142] By comparison Figure 7 (Example 4), and Figures 9-11From the reflectivity test result graphs of (Example 6-Example 8), it can be concluded that when the film thickness of the starting layer and the ending layer are different and the thickness of the intermediate layers are the same; or when the thickness of the starting layer and the ending layer are the same and the thickness of the intermediate layers are different, the reflectivity of the pigment in the non-red light band (400nm-610nm) increases significantly, causing the pigment to be mixed with other colors.

[0143] By comparison Figure 7 (Example 4) and Figure 12 From the reflectivity test results of (Comparative Example 1), it can be seen that the reflectivity of Comparative Example 1 in the red light band (610nm-760nm) is relatively low, and the reflectivity in the non-red light band (400nm-610nm) is relatively high, resulting in the pigment color not being pure enough and the red light color not being bright enough.

[0144] In summary, the present invention utilizes physical vapor deposition to produce red pearlescent pigments, resulting in an environmentally friendly process that produces no waste, no waste products, and superior performance to red pearlescent products produced using conventional methods. The red pearlescent pigments exhibit no shielding effect on millimeter-wave radar, meeting the requirements of autonomous driving technology. Furthermore, they exhibit both high scintillation and high hiding power, promising promising applications in automotive coatings.

[0145] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A red pearlescent pigment, characterized in that: The red pearlescent pigment comprises a laminated oxide film prepared alternately with silicon dioxide and titanium dioxide; The starting film layer and the ending film layer of the stacked oxide film are silicon dioxide films; The number of film layers of the stacked oxide film is 5 to 13.

2. The red pearlescent pigment according to claim 1, characterized in that The thickness of the starting film layer and the thickness of the ending film layer are independently 10 nm to 80 nm.

3. The red pearlescent pigment according to claim 1, characterized in that In the intermediate film layer, the thickness of each silicon dioxide film layer is independently 110 nm to 150 nm.

4. The red pearlescent pigment according to claim 1, characterized in that In the intermediate film layer, the thickness of each titanium dioxide film layer is independently 60nm-100nm.

5. A method for preparing the red pearlescent pigment according to any one of claims 1 to 4, characterized in that: The method comprises the following preparation steps: A silicon dioxide film is deposited on the surface of the substrate as a starting film layer by using a physical vapor deposition method; A titanium dioxide film and a silicon dioxide film are alternately plated on the starting film layer, and after the number of plated layers is reached and the silicon dioxide film is used as the termination film layer, the plated film is stopped to obtain a laminated oxide film; After the laminated oxide film is demoulded, a red pearlescent pigment is obtained.

6. The preparation method according to claim 5, characterized in that During the coating process, the coating rate of each film layer is independently selected from 0.5 nm / s to 4 nm / s.

7. The preparation method according to claim 5, characterized in that During the titanium dioxide coating process, an oxidizing gas is introduced; The oxidizing gas is selected from at least one of oxygen and ozone.

8. The preparation method according to claim 5, characterized in that The material of the substrate is selected from any one of stainless steel, glass, plastic and resin.

9. The preparation method according to claim 8, characterized in that The substrate is cleaned with anhydrous ethanol, acetone and water before coating.

10. An automobile coating comprising the red pearlescent pigment according to any one of claims 1 to 4 or the red pearlescent pigment prepared by the preparation method according to any one of claims 5 to 9.

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