Coating system

Abstract

A coating system is disclosed, comprising a first coating layer formed from a first coating composition and a second coating layer formed from a second coating composition, wherein the first coating layer has an FI value of 15 or more, and the second coating composition comprises a pigment comprising a substrate overcoated with a high refractive index film layer having a refractive index greater than 1.65 and a low refractive index film layer having a refractive index less than or equal to 1.65. A coated substrate is also disclosed, comprising a substrate and the above-described coating system applied to at least a portion of the substrate.

Description

Technical Field

[0001] This invention relates to the field of coatings, and more specifically to a coating system, particularly a coating system for automobiles. Background Technology

[0002] The exterior color of a car is one of the most important factors influencing customer purchasing decisions. To attract customers, automakers favor coatings that provide vibrant and stable colors. Therefore, developing automotive coatings that offer excellent and stable appearance while also meeting mechanical performance and environmental requirements is of practical significance and has excellent development prospects. Summary of the Invention

[0003] The inventors have conducted extensive research and developed a coating system that is applicable to automotive substrates and provides excellent and stable appearance.

[0004] The present invention provides a coating system comprising a first coating and a second coating, wherein the first coating is formed by a first coating composition and the second coating is formed by a second coating composition, wherein the first coating has an FI value of 15 or higher, and the second coating composition comprises a pigment comprising a substrate covering a high refractive index film layer and a low refractive index film layer, wherein the refractive index of the high refractive index film layer is greater than 1.65 and the refractive index of the low refractive index film layer is less than or equal to 1.65.

[0005] The present invention also provides a coated substrate, comprising a substrate and the coating system applied to at least a portion of the substrate.

[0006] The features and advantages of the present invention will be specifically presented in the following detailed description of the embodiments. Detailed Implementation

[0007] In this application, unless otherwise expressly stated, the use of the singular includes the plural and the plural includes the singular. For example, although “one” pigment is mentioned herein, one or more of the same substance may be used.

[0008] In this application, the terms "comprising," "including," and "containing" are not intended to limit the invention and exclude any variations or additions. Furthermore, although the invention has used terms such as "comprising" to describe coating compositions, preparation methods, etc., the coating compositions, preparation methods, etc., detailed herein may also be described as "consisting substantially of..." or "consisting of...". In this case, "consisting substantially of..." means that any additional ingredients will not have a substantial impact on the properties of the coating formed by the coating composition.

[0009] In this application, unless otherwise expressly stated, “or” is used to mean “and / or”, even if “and / or” may be explicitly used in certain circumstances. Furthermore, it should be understood that any numerical range listed herein is intended to include all subranges contained therein. For example, the range “1 to 10” is intended to include all subranges between the listed minimum value 1 and the listed maximum value 10 (inclusive), that is, all subranges having a minimum value equal to or greater than 1 and a maximum value equal to or less than 10.

[0010] Except as explicitly stated in the embodiments or otherwise, it should be considered that the numerical values ​​of all representative components, etc., used in the specification and claims are all subject to variation in all cases according to the term "about". Therefore, unless stated to the contrary, the numerical parameters listed in the following specification and claims are approximate values ​​and may vary according to the performance desired by the invention. At least, not to limit the application of the doctrine of equivalence to the scope of the claims, each numerical parameter should be interpreted in significant figures and subject to ordinary rounding.

[0011] Although the numerical ranges and parameters described in this invention are approximate, the numerical values ​​listed in the specific embodiments are recorded as accurately as possible. However, any numerical value inherently possesses a certain degree of error, which is a necessary consequence of the standard deviation derived from the corresponding measurement method.

[0012] This invention relates to a coating system comprising a first coating and a second coating, wherein the first coating is formed from a first coating composition, and the second coating is formed from a second coating composition, wherein the first coating has an FI value of 15 or higher, and the second coating composition comprises a pigment comprising a substrate covering a high-refractive-index film and a low-refractive-index film, wherein the high-refractive-index film has a refractive index greater than 1.65, and the low-refractive-index film has a refractive index less than or equal to 1.65. As used herein, the term "refractive index" can be determined according to the method of ISO 489:2022.

[0013] In the coating system according to the present invention, a first coating with a specific high FI value and a second coating comprising a specific pigment work together to achieve excellent appearance. The high FI value of the first coating provides a bright color background and enhanced shimmer characteristics, while the second coating comprising the specific pigment provides color that changes with angle. The coating system visually exhibits a distinct purple-to-green-to-blue effect, with a specific, three-dimensional color texture and shimmer without appearing rough. Furthermore, the coating system provides color stability, making it easier to control the color across different batches, compared to a coating system containing only the first coating.

[0014] In the coating system according to the invention, the first coating is closer to the substrate than the second coating, and no other coating is present between the first coating and the second coating. Suitably, other coatings (one or more) may also be included between the first coating and the substrate. For example, an electrophoretic coating and / or an intermediate coating may also be included between the first coating and the substrate. Suitably, other coatings (one or more) may also be included outside the second coating (away from the substrate direction). For example, a varnish coating may also be included outside the second coating.

[0015] In the coating system according to the invention, the first coating composition and the second coating composition can be applied wet-on-wet. That is, the first coating composition and the second coating composition can cure into a film simultaneously, i.e., the first coating composition is not cured before the second coating composition is applied. "Cure" refers to the coating composition forming a hardened coating film through polymerization and / or crosslinking of at least a portion of its components, or through drying.

[0016] The first coating and the second coating can be obtained by heating. The first coating composition and the second coating composition can be cured at a temperature of 80-140°C. Therefore, the first coating composition and the second coating composition can be low-temperature curing systems (e.g., less than 120°C, such as 80°C to less than 120°C) or high-temperature curing systems (e.g., 120°C or higher, such as 120-140°C).

[0017] In this article, the FI value refers to the angle-dependent colorimetric index, which is related to the color luminance at various angles. The larger the FI value, the greater the difference between small angles (e.g., 15°, 25°) and large angles (e.g., 75°, 110°), and the closer the color is to a mirror effect. In this article, the luminance values ​​(L) at 15°, 45°, and 110° can be measured using a commercially available BYK colorimeter, and then the FI value can be calculated using the following formula: FI=2.69 (L 15° - L 110° ) 1.11 / ( L 45° ) 0.86 The first coating has an FI value of 15 or higher. In this document, the FI value of the coating refers to the FI value of the coating after complete curing. Suitably, the first coating may have an FI value between 15 and 24. For example, the first coating may have an FI value of 16, 17, 18, 19, 20, 21, 22, or 23. For example, the FI value of the first coating may be 15 or higher, 16 or higher, 17 or higher, 18 or higher, 19 or higher, 20 or higher, 21 or higher, 22 or higher, or 23 or higher. For example, the FI value of the first coating may be 24 or lower, 23 or lower, 22 or lower, 21 or lower, 20 or lower, 19 or lower, 18 or lower, 17 or lower, or 16 or lower. For example, the FI value of the first coating may be 16 to 22, 15 to 20, or within a range of any two of the above values.

[0018] Suitably, the first coating may have a G value of 6 or higher. In this document, the G value of the coating refers to the G value of the coating after complete curing. Suitably, the first coating may have a G value of 6 to 10. For example, the first coating may have a G value of 6.5, 7, 7.5, 8, 8.5, 9, or 9.5. For example, the G value of the first coating may be 6 or higher, 6.5 or higher, 7 or higher, 7.5 or higher, 8 or higher, 8.5 or higher, 9 or higher, or 9.5 or higher. For example, the G value of the first coating may be 10 or lower, 9.5 or lower, 9 or lower, 8.5 or lower, 8 or lower, 7.5 or lower, 7 or lower, or 6.5 or lower. For example, the G value of the first coating may be 6 to 8, 6.5 to 9, or within a range of any two of the above values. The “G value” refers to the shimmer of the coating, which represents the intensity of the color’s shimmer under a light source. The smaller the G value, the lower the shimmer intensity, and the closer the color is to a delicate mirror effect. In this article, the G value can be obtained by testing with a commercially available BYK colorimeter.

[0019] Suitably, the first coating may have a dry film thickness of 8-18 micrometers. The "dry film thickness" refers to the thickness of the coating after complete curing. For example, the first coating may have a dry film thickness of 9, 10, 11, 12, 13, 14, 15, 16, or 17 micrometers. For example, the dry film thickness of the first coating may be 8 micrometers or higher, 9 micrometers or higher, 10 micrometers or higher, 11 micrometers or higher, 12 micrometers or higher, 13 micrometers or higher, 14 micrometers or higher, 15 micrometers or higher, 16 micrometers or higher, or 17 micrometers or higher. For example, the dry film thickness of the first coating may be 18 micrometers or lower, 17 micrometers or lower, 16 micrometers or lower, 15 micrometers or lower, 14 micrometers or lower, 13 micrometers or lower, 12 micrometers or lower, 11 micrometers or lower, 10 micrometers or lower, or 9 micrometers or lower. For example, the dry film thickness of the first coating may be 9 to 16 micrometers, 12 to 15 micrometers, or within the range of any two of the above values.

[0020] The first coating may be formed from an aqueous first coating composition. In this document, "aqueous" means that the solvent of the coating composition contains at least 50 wt% water based on the total weight of the solvent.

[0021] The first coating composition forming the first coating may include coated aluminum powder for water-based systems and / or passivated non-coated aluminum powder for automotive paints. Suitably, the aluminum powder may include silicon-coated aluminum powder. Based on the total weight of the first coating composition, the aluminum powder may be present in the first coating composition in an amount of 2-10 wt%.

[0022] The first coating composition may include a film-forming component. "Film-forming" means that the component, upon hardening and / or curing, is capable of forming a continuous film on a surface. The film-forming component may include, for example, a film-forming resin and optionally a crosslinking agent for use therein. In this document, film-forming resin and film-forming agent are used interchangeably. In this document, crosslinking agent, curing agent, and hardener are used interchangeably. The film-forming resin may react with itself, i.e., undergo a self-crosslinking reaction, or it may react with a crosslinking agent to form a film.

[0023] Suitably, the film-forming resin may include an acrylic resin. The acrylic resin refers to a polymer with (meth)acrylic acid monomers as its basic component. The "basic component" means that the (meth)acrylic acid monomers constitute at least 50 wt% of all polymeric monomers, for example, at least 70 wt%, at least 80 wt%, or even at least 90 wt%. The acrylic resin may contain hydroxyl groups.

[0024] Suitably, the film-forming resin may include a polyester resin. The polyester resin refers to a polymer generated from a polyol and a polyacid via a polyesterification reaction, wherein the polyol is a compound containing two or more hydroxyl groups per molecule, and the polyacid is a compound containing two or more carboxyl groups per molecule. The polyester resin may contain hydroxyl groups.

[0025] Suitably, the crosslinking agent may comprise an amino resin. Suitably, the crosslinking agent may comprise a melamine-formaldehyde resin. The crosslinking agent may react with the film-forming resin during curing / hardening.

[0026] In addition to aluminum powder, the first coating composition may also include another effect pigment. Suitably, the other effect pigment may include mica powder. The other effect pigment may be surface-treated to suit the water-based coating composition.

[0027] The first coating composition may include pigments. The pigments may be any pigment suitable for water-based coating compositions. The pigments may comprise inorganic and / or organic pigments.

[0028] The first coating composition may include a solvent. The solvent may include water, comprising 50 wt% or more of the total solvent weight. The solvent may also include an organic solvent. Suitably, the organic solvent may include ethylene glycol hexyl ether (hexyl cellosolve).

[0029] The first coating composition may also include one or more of the following other additives: wetting additives, pinhole eliminating additives, curing catalysts, defoamers, plasticizers, ultraviolet absorbers, light stabilizers, adhesion promoters, surface leveling agents, pH adjusters, substrate wetting agents, thickeners, fillers, etc.

[0030] The second coating composition includes a special effect pigment comprising a substrate covering a high-refractive-index film and a low-refractive-index film, wherein the high-refractive-index film has a refractive index greater than 1.65, and the low-refractive-index film has a refractive index less than or equal to 1.65. Suitably, the pigment may include at least two high-refractive-index films and at least two low-refractive-index films, wherein the high-refractive-index films and the low-refractive-index films are arranged alternately. For example, the pigment may include 2, 3, 4, 5, 6, 7, 8, or 9 high-refractive-index films and 2, 3, 4, 5, 6, 7, 8, or 9 low-refractive-index films. Suitably, the thickness of each of the high-refractive-index films is 10-400 nm. Suitably, the thickness of each of the low-refractive-index films is 10-700 nm.

[0031] Suitablely, the substrate may include a chromium-containing material. The high-refractive-index film layer (one or more) and / or low-refractive-index film layer (one or more) may be disposed on both sides of the substrate.

[0032] Based on the total weight of the second coating composition, the pigment content may be 0.3 wt% or higher, suitably 0.5 wt% or higher, such as 1 wt% or higher, and / or 5 wt% or lower, suitably 4 wt% or lower, such as 3 wt% or lower. Suitably, the pigment content may be 0.3-5 wt%, suitably 0.5-4 wt%, 1-3 wt%, or any range at either end of the above values. Based on the total weight of the cured second coating, the pigment content may be no more than 25 wt%, suitably 10-25 wt%.

[0033] The second coating composition may include a film-forming component. "Film-forming" means that the component, upon hardening and / or curing, is capable of forming a continuous film on a surface. The film-forming component may include, for example, a film-forming resin and optionally a crosslinking agent for use therein. In this document, film-forming resin and film-forming agent are used interchangeably. In this document, crosslinking agent, curing agent, and hardener are used interchangeably. The film-forming resin may react with itself, i.e., undergo a self-crosslinking reaction, or it may react with a crosslinking agent to form a film.

[0034] The film-forming resin in the second coating composition may include acrylic resin and / or polyester resin. The crosslinking agent may include amino resin. The acrylic resin, polyester resin, and / or amino resin used in the second coating composition may be the same as or different from those described in the first coating composition.

[0035] The second coating composition may further include one or more other pigments. These other pigments are different from the pigments described above that include high-refractive-index and low-refractive-index films. The other pigments may include organic pigments, inorganic pigments, and / or effect pigments. If present, the sum of the contents of these other pigments and the pigments described above that include high-refractive-index and low-refractive-index films shall not exceed 5 wt%, that is, less than or equal to 5 wt% of the total weight of the second coating composition.

[0036] In the second coating composition, the content of pigments (including pigments in high-refractive-index and low-refractive-index films, and one or more other pigments) can also be expressed by the pigment-to-binder ratio. The "pigment-to-binder ratio (P / B)" refers to the solid weight ratio of the pigments in the second coating composition to the binders (i.e., film-forming resins and crosslinking agents) in the second coating composition. Suitably, the second coating composition has a P / B ratio of 0.1-0.4.

[0037] The second coating composition may include a solvent. The solvent may include water, comprising 50 wt% or more of the total solvent weight. The solvent may also include an organic solvent. Suitably, the organic solvent may include ethylene glycol hexyl ether (hexyl cellosolve).

[0038] The second coating composition may also include one or more of the following other additives: wetting additives, pinhole eliminating additives, curing catalysts, defoamers, plasticizers, ultraviolet absorbers, light stabilizers, adhesion promoters, surface leveling agents, pH adjusters, substrate wetting agents, thickeners, fillers, etc.

[0039] Suitably, the second coating formed by the second coating composition can have a dry film thickness of 5-15 micrometers. The "dry film thickness" refers to the thickness of the coating after complete curing. For example, the second coating can have a dry film thickness of 6, 7, 8, 9, 10, 11, 12, 13, or 14 micrometers. For example, the dry film thickness of the second coating can be 5 micrometers or higher, 6 micrometers or higher, 7 micrometers or higher, 8 micrometers or higher, 9 micrometers or higher, 10 micrometers or higher, 11 micrometers or higher, 12 micrometers or higher, 13 micrometers or higher, or 14 micrometers or higher. For example, the dry film thickness of the second coating can be 15 micrometers or less, 14 micrometers or less, 13 micrometers or less, 12 micrometers or less, 11 micrometers or less, 10 micrometers or less, 9 micrometers or less, 8 micrometers or less, 7 micrometers or less, or 6 micrometers or less. For example, the dry film thickness of the second coating can be 6 to 12 micrometers, 6 to 8 micrometers, or within the range of any two of the above values.

[0040] In the coating system according to the invention, the first coating and the second coating work together to produce excellent color effects. The coating system according to the invention has a visually distinct purple-to-green-blue effect, and the color texture has a three-dimensional, layered, and shimmering quality without appearing rough. In this document, the coating system is characterized by CIE Lab color difference parameters, thereby partially reflecting the excellent appearance of the coating system. For example, the coating system according to the invention can have an L(15) greater than 100, an L(75) of 15-25, and / or an L(110) of 15-25. The L(15), L(75), and L(110) represent L values ​​(luminance values) at 15°, 75°, and 110°, respectively, and these L values ​​are chromaticity values ​​based on CIE Lab color difference theory, which can be measured using a colorimeter. Suitably, the a(-15) and a(45) of the coating system differ by at least 2 units. The values ​​a(-15) and a(45) represent the a values ​​at -15° and 45°, respectively, where the a values ​​are chromaticity values ​​based on the CIE Lab color difference theory and can be measured using a colorimeter. Suitably, the b(-15) and b(45) of the coating system differ by at least 15 units. The values ​​b(-15) and b(45) represent the b values ​​at -15° and 45°, respectively, where the b values ​​are chromaticity values ​​based on the CIE Lab color difference theory and can be measured using a colorimeter.

[0041] The coating system according to the invention can provide an FI value of 12 or higher.

[0042] The present invention also provides a coated substrate, comprising a substrate and the aforementioned coating system applied to at least a portion of the substrate. The application may refer to coating the substrate with a coating composition, or to applying a film / sheet formed from the coating composition of the coating system onto the substrate by adhesion or other methods. Suitably, the coated substrate according to the present invention comprises a substrate and the aforementioned coating system coated on at least a portion of the substrate. In this document, the application can be achieved by methods known in the art, including but not limited to spraying, dipping, roller coating, brush coating, robotic precision coating, etc. The substrate may include metal and / or plastic substrates. For example, the substrate may include steel, aluminum, PP, carbon fiber, and / or nylon substrates. Suitably, the substrate is part of a vehicle.

[0043] Example

[0044] The following examples are intended to illustrate the present invention and should not be construed as limiting the invention in any way.

[0045] Example 1

[0046] An electrophoretic coating, an intermediate coating, an aluminum undercoat (i.e., the first coating), and a clear coat are sequentially applied to the surface of a steel substrate. The dry film thickness of the electrophoretic coating is 25-32 μm, the intermediate coating is 22-30 μm, the aluminum undercoat is 12-15 μm, and the clear coat is 40-50 μm. According to the method for determining the FI value described above, the FI value of the aluminum undercoat is 15.

[0047] The aluminum undercoat is formed from a coating composition as shown in Table 1.

[0048] Table 1.

[0049] Example 2

[0050] An electrophoretic coating, a mid-coat, a flash coating (i.e., the second coating), and a clear coat are sequentially applied to the surface of a steel substrate. The dry film thickness of the electrophoretic coating is 25-32 μm, the mid-coat is 22-30 μm, the flash coating is 6-8 μm, and the clear coat is 40-50 μm. The electrophoretic coating, mid-coat, and clear coat in Example 2 are the same as those used in Example 1.

[0051] The glitter coating is formed from a coating composition as shown in Table 2.

[0052] Table 2

[0053] The pigment described above has a substrate with both high-refractive-index and low-refractive-index film layers.

[0054] Example 3

[0055] An electrophoretic coating, a mid-coat, a flash coating (a control coating corresponding to the second coating), and a clear coat were sequentially applied to the surface of a steel substrate. The dry film thickness of the electrophoretic coating was 25-32 μm, the mid-coat coating was 22-30 μm, the flash coating was 6-8 μm, and the clear coat was 40-50 μm. The electrophoretic coating, mid-coat, and clear coat in Example 3 were the same as those used in Examples 1-2.

[0056] The glitter coating is formed from a coating composition as shown in Table 3.

[0057] Table 3

[0058] Example 4

[0059] An electrophoretic coating, a mid-coat, the aluminum undercoat of Example 1, a flash coating of Example 3, and a clear coat were sequentially applied to the surface of a steel substrate. The dry film thicknesses of the electrophoretic coating, mid-coat, aluminum undercoat, flash coating, and clear coat were 25-32 μm, 22-30 μm, 12-15 μm, 6-8 μm, and 40-50 μm, respectively. The electrophoretic coating, mid-coat, and clear coat in Example 4 were the same as those used in Examples 1-3.

[0060] Example 5

[0061] An electrophoretic coating, a mid-coat, the aluminum undercoat of Example 1, a flash coating of Example 2, and a clear coat were sequentially applied to the surface of a steel substrate. The dry film thicknesses of the electrophoretic coating, mid-coat, aluminum undercoat, flash coating, and clear coat were 25-32 μm, 22-30 μm, 12-15 μm, 6-8 μm, and 40-50 μm, respectively. The electrophoretic coating, mid-coat, and clear coat in Example 5 were the same as those used in Examples 1-4.

[0062] As shown above, Example 1 includes an aluminum base coating with a high FI value according to the present invention but does not include a glitter coating; Example 2 does not include an aluminum base coating but includes a glitter coating using a specific pigment according to the present invention; Example 3 does not include an aluminum base coating but includes a control glitter coating (without using a specific pigment); Example 4 includes an aluminum base coating with a high FI value according to the present invention and a control glitter coating; and Example 5 includes an aluminum base coating with a high FI value according to the present invention and a glitter coating using a specific pigment according to the present invention.

[0063] The coatings formed in Examples 1-5 were visually observed. The coating of Example 5 had a significantly better appearance than that of Examples 1-4. Example 5 produced a color with a very obvious shimmering effect, and also had a special angle-dependent color effect. The front was bright and shimmering like the Milky Way in summer, while the sides were very dark. Furthermore, the obvious shimmering blue-purple on the front transitioned smoothly to the dark blue-green on the sides, like a deep starry sky effect. In addition, the coating of Example 5 was characterized by CIE Lab color difference parameters, which met the following conditions: L(15) was greater than 100, L(75) was 15-25, and / or L(110) was 15-25; a(-15) and a(45) differed by at least 2 units; and b(-15) and b(45) differed by at least 15 units.

[0064] Although specific aspects of the invention have been explained and described, it will be apparent to those skilled in the art that many other changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, the appended claims are intended to cover all such changes and modifications that fall within the scope of the invention.

Claims

1. A coating system comprising a first coating and a second coating, the first coating being formed from a first coating composition, the second coating being formed from a second coating composition, wherein the first coating has an FI value of 15 or higher, the second coating composition comprising a pigment, the pigment comprising a substrate covering a high refractive index film and a low refractive index film, the high refractive index film having a refractive index greater than 1.65, and the low refractive index film having a refractive index less than or equal to 1.

65.

2. The coating system of claim 1, wherein the first coating has a FI value of 15-24.

3. The coating system of claim 1 or 2, wherein the pigment comprises at least two high refractive index film layers and at least two low refractive index film layers.

4. The coating system of claim 3, wherein the high refractive index film layer and the low refractive index film layer are arranged alternately.

5. The coating system according to any one of claims 1-4, wherein the thickness of each layer in the high refractive index film is 10-400 nm, and the thickness of each layer in the low refractive index film is 10-700 nm.

6. The coating system of any one of claims 1-5, wherein the first coating has a G value of 6 or higher.

7. The coating system according to any one of claims 1-6, comprising 10-25 wt% pigment based on the total weight of the cured second coating.

8. The coating system according to any one of claims 1-7, wherein the first coating has a dry film thickness of 8-18 micrometers and the second coating has a dry film thickness of 5-15 micrometers.

9. The coating system according to any one of claims 1-8, wherein the coating system provides a coating gloss of L (15) greater than 100, L (75) of 15-25, and / or L (110) of 15-25.

10. The coating system of any one of claims 1-9, wherein the coating system provides an FI value of 12 or higher.

11. The coating system according to any one of claims 1-10, wherein the coating system provides a difference of at least 2 units between a(-15) and a(45), and / or a difference of at least 15 units between b(-15) and b(45).

12. The coating system according to any one of claims 1-11, wherein both the first coating composition and the second coating composition are water-based.

13. The coating system according to any one of claims 1-12, wherein the first coating composition and the second coating composition are applied wet-on-wet.

14. The coating system according to any one of claims 1-13, wherein the second coating composition comprises 0.3-5 wt% pigment based on the total weight of the coating composition.

15. A coated substrate, comprising a substrate and a coating system as described in any one of claims 1-14 applied to at least a portion of the substrate.

16. The coated substrate of claim 15, wherein the substrate comprises a metal and / or plastic substrate.

17. The coated substrate as claimed in claim 15 or 16, wherein the substrate is part of a vehicle.

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