Effect pigments with flash

Abstract

Based on effect pigments of a transparent plate-shaped substrate, the substrate contains a near refractive index layer coating close to the refractive index of the substrate, thereby effectively increasing the thickness of the substrate to produce higher flash.

Description

[0001] Glitter effects have been used as design elements in industrial design for decades. Glitter effects are gaining attention in cosmetic applications, packaging, printing inks and all types of coatings. Technically, glitter effects are produced by incorporating small reflective flakes with a diameter of about 5-1000 μm into a coating on a surface or as a bulk coloration of plastics or cosmetic powders.

[0002] There are some restrictions on particle size and thickness in industrial coatings. The reason for this is that the coatings are significantly thinner than 50 μm after drying. In automotive coatings, for example, modern basecoats are less than 20 μm in thickness. The resulting requirement for the luster pigments is that they should be small enough to allow a smooth basecoat to be obtained with high gloss and at the same time strong luster.

[0003] Effect pigments based on glass flakes show an intense sparkle. In particular, oxide-coated glass flakes with a diameter of 50-250 μm and a thickness of 1-5 μm show the desired effect. However, automotive undercoatings are not feasible with these flakes due to the large particle size. Smaller (less than 20 μm) and thinner (less than 500 nm) glass flakes have been tested as substrates, but the reproducibility has been poor so far with regard to thickness- and shape-variations on a production scale.

[0004] A more successful substrate is Al2O3 flakes synthesized in an expensive crystallization process. Such flakes are very uniform in size (D50=15-20 μm) and very smooth after coating with iron oxide or titanium oxide. They reflect light very well and are widely used in automotive basecoats. However, the high cost and abrasion of Al2O3 flake-based pigments have created a market demand for more cost-effective solutions. In particular, the abrasion of Al2O3 requires more expensive equipment in the paint shop to withstand the harsh abrasion conditions of paints based on it.

[0005] Mica-based effect pigments with similar particle sizes give only a moderate sparkle effect compared to Al2O3 platelet-based effect pigments. The use of synthetic mica as a matrix for effect pigments allows for an increase in the sparkle properties, since synthetic mica has a smoother surface quality compared to natural mica. However, the sparkle properties of synthetic mica-based effect pigments are still not as strong as those of Al2O3 platelets. For this reason, the inventors conducted intensive research with a view to selectively increasing the sparkle of the platelets without sacrificing suitability for use in thin basecoats.

[0006] It has surprisingly been found that the sparkle effect of any oxide coated flake can be adjusted by applying an inorganic coating with a close refractive index directly on top of the given flake and then applying a coating with a high refractive index metal oxide. This discovery has not been disclosed in the prior art to date.

[0007] US10214651B1 relates to effect pigments for use with glass frits, wherein the effect pigments comprise a substrate coated with various layers, including a first layer of a substrate selected from Al2O3, SiO2, zirconium silicate ZrSiO4, mullite 3Al2O3×2SiO2 or 2Al2O3×SiO2 (sintered or fused mullite) or alkaline earth metal silicates (MSiO3, wherein M is Mg 2+ , Ca 2+ , Sr 2+ Or Ba 2+ , or M2Si3O8, where M is Mg 2+ , Ca 2+ , Sr 2+ Or Ba 2+ ) The details of the first low refractive index layer or its purpose are not disclosed.

[0008] US7699927B1 provides a protective layer for effect pigments comprising a SiO2 layer. The thickness of the SiO2 is 2-20 nm or 0.5-10% by weight of the pigment. These effect pigments do not produce a sparkling effect.

[0009] CN108165053A provides a high chroma anatase effect pigment, which is achieved by a high-low-high refractive index stack. There is an additional silica layer on the mica before the optical layer, but its purpose is not completely clear. The amount of silica in this initial layer is 0.01-2% by weight, so no sparkle effect is produced.

[0010] US7485183B1 discloses blends of commercially available pigments, including glass flake-based effect pigments, with various coatings, which may contain a silica layer between the glass flakes and other coatings. The purpose of the silica layer is not disclosed.

[0011] US8883879B1 relates to the preparation of pigment particles in which effect pigments are attached to a support material. Effect pigments known in the art are used, including effect pigments comprising glass flakes as a substrate. Glass flake-based effect pigments may also have a silicon dioxide layer between the glass flake and the coating. The purpose of the silicon dioxide layer is to protect the glass flake from leaching during wet chemical coating.

[0012] US8500901B1 discloses interference pigments based on substrates of aluminum oxide and glass sheets. The purpose of the silicon dioxide layer is to provide a silvery white interference pigment with high gloss (L value) and chromaticity (tinting strength C*) and mechanical stability. The glossiness mentioned therein has the meaning of brightness (L value) and relates to CIELab system and multi-angle color measurement. The principle is to measure the angle-dependent reflectivity and mathematically derive color data such as C*, L*, h, a, b in the visible light range.

[0013] US10597544B1 relates to effect pigments based on a typical substrate, preferably glass flakes, which have 8 coating layers, of which the first layer is silicon dioxide. The stated purpose of the silicon dioxide coating is to protect the glass surface from chemical modifications, such as swelling, leaching or dissolution of glass components in aggressive acidic coating solutions.

[0014] EP2917285 A1 relates to multilayer coated effect pigments having at least 4 oxide layers and optionally a first SiO2 layer. The thickness of the SiO2 layer is 3-150 nm. The main purpose of this layer is to protect the glass sheet substrate from chemical attack and optionally includes carbon black to increase hiding power. The next layer is also a low refractive index layer with a thickness of 1-50 nm. No clear purpose of this layer is stated.

[0015] US8268069B1 relates to glass sheets coated with various layers and optionally a first layer comprising a SiO2 coating. The purpose of the silica coating is to protect the glass surface against chemical modifications such as swelling, leaching or dissolution of glass components in aggressive acidic coating solutions.

[0016] Although the cited patent references mention some type of low refractive index layer on the substrate prior to subsequent optical layers, there is no indication that the purpose of this layer is to increase the effective thickness of the substrate and obtain sparkle-enhancing effect pigments.

[0017] Small particle size substrates, especially thin substrates, do not provide much sparkle when converted into effect pigments by coating with various optical layers. In order to enhance the sparkle of effect pigments based on small particle size substrates, a near refractive index matching layer is applied to the substrate before applying the optical layers, thereby making the substrate essentially thicker and producing more sparkle.

[0018] Citation or identification of any document in this application is not an admission that it represents prior art to the present invention.

[0019] The present invention relates to effect pigments based on a transparent plate-like substrate having a near-refractive index coating matched to the substrate, thereby effectively increasing the substrate thickness, followed by any combination of optical layers. In one embodiment, the substrate is a mineral belonging to the mica group, for example, muscovite is a natural mica and fluorophlogopite is a synthetic mica. Other types of transparent plate-like substrates include glass flakes, SiO2, Al2O3, BiOCl, kaolin, ZnO, BN and perlite. In one embodiment, the near-refractive index coating has a refractive index within 0.3 of the substrate and can contain any material or combination of materials that provides the desired refractive index. Examples of materials for the near-refractive index matching coating include, but are not limited to, SiO2, Al2O3 and MgO. Again, two or more metal oxides can be mixed to produce the desired refractive index matching layer using the following formula:

[0020] n=X A ·n A +X B ·n B

[0021] Where n is the resulting refractive index of the blend, X A is the mole fraction of component A, n A is the refractive index of component A, X B is the molar fraction of component B and n B is the refractive index of component B. Table 1 contains a listing of relevant materials and literature values ​​of refractive index. Table 2 gives some examples of some blends that can be used to match the refractive index of mica.

[0022] Table 1. Related materials and refractive index

[0023] Material Refractive Index <![CDATA[SiO2]]> 1.46 MgO 1.736 <![CDATA[Al2O3]]> 1.765 <![CDATA[SnO2]]> 1.997 ZnO 2.008 Mica 1.60

[0024] Table 2. Metal oxide blends matching the refractive index of mica

[0025] A <![CDATA[X A ]]> B <![CDATA[X B ]]> <![CDATA[SiO2]]> 0.54 <![CDATA[Al2O3]]> 0.46 <![CDATA[SiO2]]> 0.74 <![CDATA[SnO2]]> 0.26 <![CDATA[SiO2]]> 0.49 MgO 0.51 <![CDATA[SiO2]]> 0.74 ZnO 0.26

[0026] The expression "near-refractive index coating that matches the substrate" means that the near-refractive index coating has a refractive index within 0.3 of the refractive index of the one or more transparent plate-like substrates.

[0027] The expression "thickness" of a coating refers to the physical thickness of the coating.

[0028] Although the near index matching coating can be applied to substrates of any size, since substrates with larger particle size distributions (PSD) inherently have more sparkle, it is more practical to apply to smaller substrates, such as those with a Dv50 (average particle size) of less than 30 microns. The near index matching coating can be applied by any method including, for example, aqueous precipitation, sol-gel, and CVD. If desired, the applied near index coating can be calcined before applying additional optical layers. Subsequent optical layers can include TiO2, Fe2O3, TiO2 / Fe2O3, TiO2 / SiO2 / TiO2, TiO2 / SiO2 / Fe2O3, Fe2O3 / SiO2 / TiO2, and Fe2O3 / SiO2 / Fe2O3. The enhanced sparkle of these effect pigments can be measured with a BYK-mac spectrophotometer and compared to effect pigments having the same optical layers on the same substrate but without the initial near index matching coating.

[0029] The use of this near index matching coating increases the substrate thickness to enhance the sparkle of the resulting effect pigment and provides a small PSD.One particular end application is automotive coatings where sparkle effects are often desired but large particle size pigments cannot be used.

[0030] The invention is further illustrated by the following set of numbered embodiments and combinations of embodiments resulting from the dependencies and back-references shown. It is particularly noted that in each case where a range of embodiments is mentioned, for example with respect to a term such as "a composition of any one of paragraphs 1-5", it is intended to explicitly disclose to the skilled person each embodiment within the range, i.e. the wording of the term should be understood by the skilled person as being synonymous with "a composition of any one of paragraphs 1, 2, 3, 4 and 5". Furthermore, it is expressly noted that the following set of embodiments is not the set of claims that defines the scope of protection, but rather represents a suitable constituent part of the specification relating to general and preferred aspects of the invention.

[0031] 1. An effect pigment composition comprising one or more transparent plate-like substrates comprising a near-refractive index coating matched to the substrate.

[0032] 2. The composition of paragraph 1, wherein the substrate is selected from mica, glass flakes, SiO2, Al2O3, BiOCl, kaolin, ZnO, BN, perlite and mixtures thereof, preferably mica, glass flakes, perlite and mixtures thereof, more preferably the substrate comprises mica, more preferably mica.

[0033] 3. The composition of paragraph 2, wherein the transparent plate-like substrate is mica selected from muscovite (natural mica) and fluorophlogopite (synthetic mica), preferably the substrate comprises fluorophlogopite, more preferably fluorophlogopite.

[0034] 4. The composition of any preceding paragraph, wherein the refractive index of the transparent plate-like substrate is in the range of 1.0-2.1, preferably 1.2-2.0, more preferably 1.3-1.9, more preferably 1.4-1.8.

[0035] 5. The composition of any preceding paragraph, wherein the near-refractive index coating has a refractive index in the range of 1.0-2.1, preferably 1.2-2.0, more preferably 1.3-1.9, more preferably 1.4-1.8.

[0036] 6. The composition of any preceding paragraph, wherein the near-refractive index coating has a refractive index within 0.3 of the substrate, preferably in the range of 0.0-0.29, more preferably 0.0-0.20, more preferably 0.0-0.15.

[0037] 7. The composition of any preceding paragraph, wherein the near-refractive index coating has a thickness in the range of 30-170 nm, preferably 40-160 nm, more preferably 50-150 nm, as determined by high resolution scanning electron microscopy.

[0038] 8. The composition of any preceding paragraph, wherein 90-100 wt %, preferably 95-100 wt %, more preferably 98-100 wt %, more preferably 99-100 wt % of the near-refractive index coating consists of SiO2, Al2O3, MgO, ZnO and mixtures thereof.

[0039] 9. The composition of any preceding paragraph, wherein the near-refractive index coating comprises a material, wherein the material is selected from SiO2, Al2O3, MgO, ZnO and mixtures thereof, preferably SiO2, Al2O3 and mixtures thereof, more preferably the material for the near-refractive index coating comprises SiO2, more preferably SiO2.

[0040] 10. The composition of any preceding paragraph, wherein the near-refractive index coating is composed of two metal oxides A and B that are mixed to produce the near-refractive index coating, wherein the refractive index of the near-refractive index coating is determined using the formula:

[0041] n=X A ·n A +X B ·n B ,

[0042] Where n is the resulting refractive index of the near-refractive index coating; X A is the molar fraction of metal oxide A; n A is the refractive index of metal oxide A; X B is the molar fraction of metal oxide B and n B is the refractive index of metal oxide B.

[0043] 11. The composition of any preceding paragraph, wherein the substrate has a Dv50 in the range of 5-100 microns, as determined according to Reference Example 1, preferably the substrate has a Dv50 less than 30 microns, more preferably the substrate has a Dv50 in the range of 5-30 microns, more preferably 5-25 microns.

[0044] 12. The composition of any preceding paragraph, further comprising a combination of subsequent optical layers.

[0045] 13. The composition of paragraph 12, wherein the subsequent optical layer is selected from TiO2, Fe2O3, TiO2 / Fe2O3, TiO2 / SiO2 / TiO2, TiO2 / SiO2 / Fe2O3, Fe2O3 / SiO2 / TiO2 and Fe2O3 / SiO2 / Fe2O3, preferably the subsequent optical layer is selected from TiO2 and Fe2O3, more preferably the subsequent optical layer comprises a TiO2 layer, more preferably a TiO2 layer.

[0046] 14. The composition of paragraph 12 or 13, wherein each subsequent optical layer has a thickness in the range of 20-300 nm, preferably 20-180 nm, more preferably 20-130 nm, as determined by high resolution scanning electron microscopy.

[0047] 15. The composition of any preceding paragraph, having a Δ sparkle intensity ΔS_i in the range of 0.5-5.0, preferably 1.0-4.0, more preferably 2.0-3.0, as determined according to Reference Example 2.

[0048] 16. The composition of any preceding paragraph, wherein the near-refractive-index coating further comprises SnO2.

[0049] 17. The composition of any preceding paragraph, wherein the near-refractive index coating is applied by a method selected from the group consisting of aqueous precipitation, sol-gel, and chemical vapor deposition.

[0050] 18. The composition of any preceding paragraph, wherein the applied near-index coating is calcined prior to applying the additional optical layers.

[0051] 19. A printing ink, paint or coating composition comprising the composition of any one or more of paragraphs 1 to 18.

[0052] 20. The printing ink, paint or coating composition of paragraph 19 which is an automotive coating.

[0053] 21. A method of preparing a composition according to any of paragraphs 1 to 18, wherein the near-refractive index coating is applied to the transparent plate-like substrate by a method selected from aqueous precipitation, sol-gel and chemical vapor deposition.

[0054] 22. The method of paragraph 21, wherein the near-refractive index coating is fired prior to applying a combination of subsequent optical layers.

[0055] 23. A method of enhancing the sparkle of effect pigments based on a transparent plate-like substrate, comprising applying a near-refractive index coating matched to the substrate.

[0056] 24. The method of paragraph 23, wherein the substrate is selected from mica, glass flakes, SiO2, Al2O3, BiOCl, kaolin, ZnO, BN, perlite and mixtures thereof, preferably mica, glass flakes, perlite and mixtures thereof, more preferably the substrate comprises mica, more preferably mica.

[0057] 25. The method of paragraph 24, wherein the transparent plate-like substrate is a mica selected from muscovite (natural mica) and fluorophlogopite (synthetic mica), preferably the substrate comprises fluorophlogopite, more preferably fluorophlogopite.

[0058] 26. The method of paragraph 23, wherein the refractive index of the transparent plate-like substrate is in the range of 1.0-2.1, preferably 1.2-2.0, more preferably 1.3-1.9, more preferably 1.4-1.8.

[0059] 27. The method of paragraph 23, wherein the refractive index of the near-refractive index coating is in the range of 1.0-2.1, preferably 1.2-2.0, more preferably 1.3-1.9, more preferably 1.4-1.8.

[0060] 28. The method of paragraph 23, wherein the near-refractive index coating has a refractive index within 0.3 of the substrate, preferably in the range of 0.0-0.29, more preferably 0.0-0.20, more preferably 0.0-0.15.

[0061] 29. The method of paragraph 23, wherein the near-refractive index coating has a thickness in the range of 30-170 nm, preferably 40-160 nm, more preferably 50-150 nm, as determined by high resolution scanning electron microscopy.

[0062] 30. The method of paragraph 23, wherein 90-100 wt %, preferably 95-100 wt %, more preferably 98-100 wt %, more preferably 99-100 wt % of the near-refractive index coating is composed of SiO2, Al2O3, MgO, ZnO and mixtures thereof.

[0063] 31. The method of paragraph 23, wherein the near-refractive index coating comprises a material, wherein the material is selected from SiO2, Al2O3, MgO and mixtures thereof, preferably SiO2, Al2O3 and mixtures thereof, more preferably the material for the near-refractive index coating comprises SiO2, more preferably SiO2.

[0064] 32. The method of paragraph 23, wherein the near-refractive index coating is composed of two metal oxides A and B that are mixed to produce the near-refractive index coating, wherein the refractive index of the near-refractive index coating is determined using the following formula:

[0065] n=X A ·n A +X B ·n B ,

[0066] Where n is the resulting refractive index of the near-refractive index coating; X A is the molar fraction of metal oxide A; n A is the refractive index of metal oxide A; X B is the molar fraction of metal oxide B and n B is the refractive index of metal oxide B.

[0067] 33. The method of paragraph 23, wherein the substrate has a Dv50 in the range of 5-100 microns as determined according to Reference Example 1, preferably the substrate has a Dv50 of less than 30 microns, more preferably the substrate has a Dv50 in the range of 5-30 microns, more preferably 5-25 microns.

[0068] 34. The method of paragraph 23, further comprising the combination of subsequent optical layers.

[0069] 35. The method of paragraph 23, wherein the subsequent optical layer is selected from TiO2, Fe2O3, TiO2 / Fe2O3, TiO2 / SiO2 / TiO2, TiO2 / SiO2 / Fe2O3, Fe2O3 / SiO2 / TiO2 and Fe2O3 / SiO2 / Fe2O3, preferably the subsequent optical layer is selected from TiO2 and Fe2O3, more preferably the subsequent optical layer comprises a TiO2 layer, more preferably a TiO2 layer.

[0070] 36. The method of paragraph 23, wherein each subsequent optical layer has a thickness in the range of 20-300 nm, preferably 20-180 nm, more preferably 20-130 nm, as determined by high resolution scanning electron microscopy.

[0071] 37. The method of paragraph 23, having a Δ sparkle intensity ΔS_i in the range of 0.5-5.0, preferably 1.0-4.0, more preferably 2.0-3.0, determined according to Reference Example 2.

[0072] 38. The method of paragraph 23, wherein the near-refractive-index coating further comprises SnO2.

[0073] 39. The method of paragraph 23, wherein the near-refractive index coating is applied by a process selected from the group consisting of aqueous precipitation, sol-gel, and chemical vapor deposition.

[0074] 40. The method of paragraph 23, wherein the applied near-index coating is fired prior to applying the additional optical layers.

[0075] Furthermore, the present invention relates to an effect pigment comprising:

[0076] (i) a transparent plate-like substrate having a refractive index in the range of 1.0-2.1;

[0077] (ii) a first coating on the transparent plate-like substrate according to (i), the first coating comprising at least one

[0078] A first metal oxide selected from SiO2, Al2O3, MgO, ZnO and mixtures thereof;

[0079] The refractive index of the first coating according to (ii) is at most 0.3 of the refractive index of the transparent plate-like substrate according to (i).

[0080] It is preferred that the refractive index of the transparent plate-like substrate according to (i) is in the range of 1.2 to 2.0, preferably 1.3 to 1.9, more preferably 1.4 to 1.8.

[0081] It is preferred that the transparent plate-like substrate according to (i) is selected from mica, glass flakes, SiO2, Al2O3, BiOCl, kaolin, ZnO, BN, perlite and mixtures thereof, preferably mica, glass flakes, perlite and mixtures thereof, wherein more preferably the transparent plate-like substrate according to (i) comprises mica, more preferably mica.

[0082] In the case where the transparent plate-like substrate according to (i) is mica, the mica is muscovite, fluorophlogopite or a mixture thereof, preferably fluorophlogopite.

[0083] Muscovite is a natural mica and fluorophlogopite is a synthetic mica.

[0084] It is preferred that the transparent plate-like substrate according to (i) has a Dv50 measured according to Reference Example 1 in the range of 5-100 μm, more preferably 5-50 μm, more preferably 5-30 μm, more preferably 5-25 μm.

[0085] It is preferred that the refractive index of the first coating according to (ii) is in the range of 1-2.1, more preferably 1.2-2.0, more preferably 1.3-1.9, more preferably 1.4-1.8.

[0086] It is preferred that the refractive index of the first coating according to (ii) is in the range of 0-0.29, more preferably 0.0-0.20, more preferably 0.0-0.15 of the refractive index of the transparent plate-like substrate according to (i).

[0087] Preferably, 90-100 wt. %, preferably 95-100 wt. %, more preferably 98-100 wt. %, more preferably 99-100 wt. % of the first coating according to (ii) consists of the at least one first metal oxide selected from SiO2, Al2O3, MgO, ZnO and mixtures thereof.

[0088] It is preferred that the at least one first metal oxide is selected from SiO2, Al2O3, MgO and mixtures thereof, more preferably SiO2, Al2O3 and mixtures thereof, more preferably the first metal oxide comprises SiO2, more preferably SiO2.

[0089] It is preferred that the first coating according to (ii) has a thickness in the range of 30-170 nm, more preferably 40-160 nm, more preferably 50-150 nm, as determined by high resolution scanning electron microscopy.

[0090] The expression "thickness" of a coating refers to the physical thickness of the coating.

[0091] It is preferred that the first coating according to (ii) consists of k metal oxides A(i), i=1..k, k>1, wherein the refractive index n of the first coating is defined as:

[0092]

[0093] in

[0094] X A (i) is the mole fraction of the metal oxide A(i) contained in the first coating;

[0095] n A (i) is the refractive index of the metal oxide A(i) as a single compound.

[0096] It is preferred that the first coating according to (ii) further comprises SnO2.

[0097] It is preferred that the effect pigments according to any of the specific and preferred embodiments of the present invention further comprise:

[0098] (iii) a second coating on the first coating according to (ii), having a refractive index in the range of 2.2-4 and comprising at least one second metal oxide selected from TiO2, Fe2O3, Fe3O4 and mixtures thereof, preferably TiO2, Fe2O3 and mixtures thereof, more preferably the second metal oxide comprises TiO2.

[0099] In case where the effect pigment of any of the specific and preferred embodiments of the present invention comprises a second coating according to (iii), the refractive index of the second coating according to (iii) is in the range of 2.5 to 3.5.

[0100] Preferably, 90-100 wt. %, preferably 95-100 wt. %, more preferably 98-100 wt. %, more preferably 99-100 wt. % of the second coating according to (iii) consists of the at least one second metal oxide selected from TiO2, Fe2O3, Fe3O4 and mixtures thereof.

[0101] It is preferred that the second coating according to (iii) has a thickness in the range of 20-300 nm, preferably 20-180 nm, more preferably 20-130 nm, as determined by high resolution scanning electron microscopy.

[0102] It is preferred that the second coating according to (iii) further comprises SnO2.

[0103] It is preferred that the effect pigments according to any of the specific and preferred embodiments of the present invention comprise two coatings, wherein

[0104] the first coating according to (ii) comprises SiO2 and the second coating according to (iii) comprises TiO2; or

[0105] The first coating according to (ii) comprises SiO 2 and the second coating according to (iii) comprises Fe 2 O 3 .

[0106] It is preferred that the effect pigments according to any of the specific and preferred embodiments of the present invention further comprise:

[0107] (iv) a third coating on the second coating according to (iii), which has a refractive index in the range of 1-4 and comprises at least one selected from SiO2, TiO2, Fe2O3, Fe3O4 and mixtures thereof, preferably

[0108] A third metal oxide of SiO2, TiO2, Fe2O3 and mixtures thereof.

[0109] In case where the effect pigment according to any of the specific and preferred embodiments of the present invention comprises a third coating according to (iv), the refractive index of the third coating according to (iv) is in the range of 2.5-3.5.

[0110] Preferably, 90-100 wt. %, preferably 95-100 wt. %, more preferably 98-100 wt. %, more preferably 99-100 wt. % of the third coating according to (iv) consists of the at least one second metal oxide selected from SiO2, TiO2, Fe2O3, Fe3O4 and mixtures thereof.

[0111] It is preferred that the third coating according to (iv) has a thickness in the range of 20-300 nm, preferably 20-180 nm, more preferably 20-130 nm, as determined by high resolution scanning electron microscopy.

[0112] It is preferred that the third coating according to (iv) further comprises SnO2.

[0113] It is preferred that the effect pigments according to any of the specific and preferred embodiments of the invention comprise three coatings, wherein the first coating according to (ii) comprises SiO2, the second coating according to (iii) comprises TiO2 and the third coating according to (iv) comprises Fe2O3.

[0114] It is preferred that the effect pigments according to any of the specific and preferred embodiments of the present invention further comprise:

[0115] (v) a fourth coating on the third coating according to (iv), having a refractive index in the range of 2.2-4 and comprising at least one fourth metal oxide selected from TiO2, Fe2O3, Fe3O4 and mixtures thereof, preferably TiO2, Fe2O3 and mixtures thereof, more preferably the second metal oxide comprises TiO2, more preferably comprises TiO2, more preferably is TiO2.

[0116] In case where the effect pigment according to any of the specific and preferred embodiments of the present invention comprises a fourth coating according to (v), the refractive index of the fourth coating according to (v) is in the range of 2.5 to 3.5.

[0117] It is preferred that 90-100 wt. %, preferably 95-100 wt. %, more preferably 98-100 wt. %, more preferably 99-100 wt. % of the fourth coating according to (v) consists of the at least one second metal oxide selected from TiO2, Fe2O3, Fe3O4 and mixtures thereof.

[0118] It is preferred that the fourth coating according to (v) has a thickness in the range of 20-300 nm, preferably 20-180 nm, more preferably 20-130 nm, as determined by high resolution scanning electron microscopy.

[0119] It is preferred that the fourth coating according to (v) further comprises SnO2.

[0120] It is preferred that the effect pigment according to any of the specific and preferred embodiments of the invention comprises four coating layers, wherein the first coating layer according to (ii) comprises SiO2, the second coating layer according to (iii) comprises TiO2, the third coating layer according to (iv) comprises SiO2 and the fourth coating layer according to (v) comprises TiO2; or

[0121] The first coating according to (ii) comprises SiO2, the second coating according to (iii) comprises TiO2; the third coating according to (iv) comprises SiO2 and the fourth coating according to (v) comprises Fe2O3; or

[0122] The first coating according to (ii) comprises SiO2, the second coating according to (iii) comprises Fe2O3; the third coating according to (iv) comprises SiO2 and the fourth coating according to (v) comprises TiO2; or

[0123] The first coating according to (ii) comprises SiO2, the second coating according to (iii) comprises Fe2O3; the third coating according to (iv) comprises SiO2 and the fourth coating according to (v) comprises Fe2O3.

[0124] It is preferred that the effect pigments according to any of the specific and preferred embodiments of the present invention have a Δ sparkle intensity ΔS_i determined according to Reference Example 2 in the range of 0.5-5.0, preferably 1.0-4.0, more preferably 2.0-3.0.

[0125] The present invention further relates to a process for preparing an effect pigment, preferably an effect pigment according to any of the specific and preferred embodiments of the present invention, comprising:

[0126] (a) providing a transparent plate-like substrate having a refractive index in the range of 1.0-2.1;

[0127] (b) comprising at least one first metal oxide selected from Si, Al, Mg, Zn and a mixture thereof

[0128] The first composition of the precursor is applied on the transparent plate-like substrate to obtain a first uncalcined coating;

[0129] (c) calcining the transparent plate-like substrate and the first uncalcined coating in air at a temperature in the range of 650-950° C. and normal pressure for a duration of 5-60 minutes;

[0130] (d) obtaining an effect pigment comprising, on the transparent plate-like substrate, a first coating comprising at least one first metal oxide selected from the group consisting of SiO2, Al2O3, MgO, ZnO and mixtures thereof, the first coating having a refractive index of at most 0.30 of the transparent plate-like substrate;

[0131] The coating according to (b) is performed by one or more of aqueous precipitation, sol-gel coating and chemical vapor deposition.

[0132] Preferably, before (c), the method further comprises:

[0133] (bi) adding a second metal oxide precursor comprising at least one selected from Ti, Fe and a mixture thereof

[0134] The composition is applied over the first coating to provide a second uncalcined coating.

[0135] It is preferred that the transparent plate-like substrate and the first uncalcined coating obtained according to (b) are calcined in air at a temperature of 650 to 950° C. and normal pressure for a duration of 5 to 60 minutes prior to (bi).

[0136] Preferably, the method according to any one of the specific and preferred embodiments of the present invention further comprises: (b.ii) applying at least one other composition to the second coating obtained according to (b.1), wherein if the coating

[0137] If at least two further compositions are applied, they are preferably applied one after the other, thereby obtaining at least a third coating on the second coating and a fourth coating on the third coating, wherein more preferably said coating is calcined before applying the further compositions on a given coating.

[0138] The present invention furthermore relates to an effect pigment obtainable or obtained by a process according to any of the specific and preferred embodiments of the present invention.

[0139] The present invention also relates to the use of the effect pigments according to any of the specific and preferred embodiments of the present invention as a component of and / or for the preparation of one or more of printing inks, paints and coating compositions.

[0140] Preferably the coating composition is an automotive coating composition.

[0141] The present invention also relates to a process for preparing one or more of a printing ink, a paint and a coating composition, comprising using as a component the effect pigments according to any of the specific and preferred embodiments of the present invention.

[0142] Preferably the coating composition is an automotive coating composition.

[0143] The present invention furthermore relates to a printing ink, paint and / or coating composition comprising or consisting of the effect pigments according to any of the specific and preferred embodiments of the present invention.

[0144] The present invention furthermore relates to the use of the effect pigments according to any of the specific and preferred embodiments of the present invention in printing inks, paints and coating compositions as a component for enhancing the sparkle effect.

[0145] The present invention also relates to a method for enhancing the sparkle effect of one or more of printing inks, paints and coating compositions, comprising using as a component the effect pigments according to any of the specific and preferred embodiments of the present invention.

[0146] The invention is further illustrated by the following set of embodiments and combinations of embodiments resulting from the indicated dependencies and back-references. It should be noted in particular that in each case where a range of embodiments is mentioned, e.g. with respect to a term such as "the effect pigment of any of embodiments 1-4", each embodiment within this range is intended to be explicitly disclosed to the skilled person, i.e. the wording of this term should be understood by the skilled person as being synonymous with "the effect pigment of any of embodiments 1, 2, 3 and 4". Furthermore, it should be explicitly noted that the following set of embodiments represents a proper constituent part of the general description of preferred aspects of the invention in the specification and therefore properly supports but does not represent the claims of the invention.

[0147] 1. An effect pigment comprising:

[0148] (i) a transparent plate-like substrate having a refractive index in the range of 1.0-2.1;

[0149] (ii) a first coating on the transparent plate-like substrate according to (i), the first coating comprising at least one

[0150] A first metal oxide selected from SiO2, Al2O3, MgO, ZnO and mixtures thereof;

[0151] The refractive index of the first coating according to (ii) is at most 0.3 of the refractive index of the transparent plate-like substrate according to (i).

[0152] 2. The effect pigment of embodiment 1, wherein the refractive index of the transparent plate-shaped substrate according to (i) is in the range of 1.2 to 2.0, preferably 1.3 to 1.9, more preferably 1.4 to 1.8.

[0153] 3. The effect pigment of embodiment 1 or 2, wherein the transparent plate-shaped substrate according to (i) is selected from mica, glass flakes, SiO2, Al2O3, BiOCl, kaolin, ZnO, BN, perlite and mixtures thereof, selected from mica, glass flakes, perlite and mixtures thereof, wherein more preferably the transparent plate-shaped substrate according to (i) comprises mica, more preferably mica.

[0154] 4. The effect pigment of embodiment 3, wherein the mica is muscovite, fluorophlogopite or a mixture thereof, preferably fluorophlogopite.

[0155] 5. The effect pigment according to any of embodiments 1 to 4, wherein the transparent plate-shaped substrate according to (i) has a Dv50 determined according to Reference Example 1 in the range of 5-100 μm, preferably 5-50 μm, more preferably 5-30 μm, more preferably 5-25 μm.

[0156] 6. The effect pigment according to any of embodiments 1 to 5, wherein the refractive index of the first coating according to (ii) is in the range of 1 to 2.1, preferably 1.2 to 2.0, more preferably 1.3 to 1.9, more preferably 1.4 to 1.8.

[0157] 7. The effect pigment according to any of embodiments 1 to 6, wherein the refractive index of the first coating according to (ii) is in the range of 0-0.29, preferably 0.0-0.20, more preferably 0.0-0.15 of the refractive index of the transparent plate-shaped substrate according to (i).

[0158] 8. The effect pigment according to any of embodiments 1 to 7, wherein 90 to 100% by weight, preferably 95 to 100% by weight, more preferably 98 to 100% by weight, more preferably 99 to 100% by weight of the first coating according to (ii) consists of the at least one first metal oxide selected from SiO2, Al2O3, MgO, ZnO and mixtures thereof.

[0159] 9. The effect pigment according to any one of embodiments 1 to 8, wherein the at least one first metal oxide is selected from SiO2, Al2O3, MgO and mixtures thereof, preferably SiO2, Al2O3 and mixtures thereof, more preferably the first metal oxide comprises SiO2, more preferably SiO2.

[0160] 10. The effect pigment according to any of embodiments 1 to 9, wherein the first coating according to (ii) has a thickness in the range of 30 to 170 nm, preferably 40 to 160 nm, more preferably 50 to 150 nm, as determined by high-resolution scanning electron microscopy.

[0161] 11. The effect pigment according to any of embodiments 1 to 10, wherein the first coating according to (ii) consists of k metal oxides A(i), i=1..k, k>1, wherein the refractive index n of the first coating is defined as:

[0162]

[0163] in

[0164] X A (i) is the mole fraction of the metal oxide A(i) contained in the first coating;

[0165] n A (i) is the refractive index of the metal oxide A(i) as a single compound.

[0166] 12. The effect pigment according to any of embodiments 1 to 11, wherein the first coating according to (ii) further comprises SnO2.

[0167] 13. The effect pigment according to any one of embodiments 1 to 12, further comprising:

[0168] (iii) a second coating on the first coating according to (ii) having a refractive index in the range of 2.2-4

[0169] And it contains at least one second metal oxide selected from TiO2, Fe2O3, Fe3O4 and mixtures thereof, preferably TiO2, Fe2O3 and mixtures thereof, and more preferably the second metal oxide contains TiO2.

[0170] 14. The effect pigment of embodiment 13, wherein the refractive index of the second coating according to (iii) is in the range of 2.5 to 3.5.

[0171] 15. The effect pigment of embodiment 13 or 14, wherein 90 to 100% by weight, preferably 95 to 100% by weight, more preferably 98 to 100% by weight, more preferably 99 to 100% by weight of the second coating according to (iii) consists of the at least one second metal oxide selected from TiO2, Fe2O3, Fe3O4 and mixtures thereof.

[0172] 16. The effect pigment according to any of embodiments 13 to 15, wherein the second coating according to (iii) has a thickness in the range of 20 to 300 nm, preferably 20 to 180 nm, more preferably 20 to 130 nm, determined according to high-resolution scanning electron microscopy.

[0173] 17. The effect pigment according to any of embodiments 13 to 16, wherein the second coating according to (iii) further comprises SnO2.

[0174] 18. The effect pigment according to any of embodiments 13 to 17, wherein the effect pigment comprises two coating layers, wherein

[0175] the first coating according to (ii) comprises SiO2 and the second coating according to (iii) comprises TiO2; or

[0176] The first coating according to (ii) comprises SiO 2 and the second coating according to (iii) comprises Fe 2 O 3 .

[0177] 19. The effect pigment according to any one of embodiments 13 to 18, further comprising:

[0178] (iv) a third coating on the second coating according to (iii), having a refractive index in the range of 1-4 and comprising at least one third metal oxide selected from SiO2, TiO2, Fe2O3, Fe3O4 and mixtures thereof, preferably SiO2, TiO2, Fe2O3 and mixtures thereof.

[0179] 20. The effect pigment of embodiment 18, wherein the refractive index of the third coating according to (iv) is in the range of 2.5 to 3.5.

[0180] 21. The effect pigment of embodiment 18 or 19, wherein 90-100% by weight, preferably 95-100% by weight, more preferably 98-100% by weight, more preferably 99-100% by weight of the third coating according to (iv) consists of the at least one second metal oxide selected from SiO2, TiO2, Fe2O3, Fe3O4 and mixtures thereof.

[0181] 22. The effect pigment according to any of embodiments 18 to 20, wherein the third coating according to (iv) has a thickness in the range of 20 to 300 nm, preferably 20 to 180 nm, more preferably 20 to 130 nm, as determined according to high-resolution scanning electron microscopy.

[0182] 23. The effect pigment according to any of embodiments 18 to 22, wherein the third coating according to (iv) further comprises SnO 2 .

[0183] 24. The effect pigment according to any of embodiments 18 to 23, wherein the effect pigment comprises three coating layers, wherein the first coating layer according to (ii) comprises SiO 2 , the second coating layer according to (iii) comprises TiO 2 and the third coating layer according to (iv) comprises Fe 2 O 3 .

[0184] 25. The effect pigment according to any one of embodiments 18 to 24, further comprising:

[0185] (v) a fourth coating on the third coating according to (iv), having a refractive index in the range of 2.2-4 and comprising at least one fourth metal oxide selected from TiO2, Fe2O3, Fe3O4 and mixtures thereof, preferably TiO2, Fe2O3 and mixtures thereof, more preferably the second metal oxide comprises TiO2, more preferably comprises TiO2, more preferably is TiO2.

[0186] 26. The effect pigment of embodiment 24, wherein the refractive index of the fourth coating according to (v) is in the range of 2.5 to 3.5.

[0187] 27. The effect pigment of embodiment 25 or 26, wherein 90-100% by weight, preferably 95-100% by weight, more preferably 98-100% by weight, more preferably 99-100% by weight of the fourth coating according to (v) consists of the at least one second metal oxide selected from TiO2, Fe2O3, Fe3O4 and mixtures thereof.

[0188] 28. The effect pigment according to any of embodiments 25 to 27, wherein the fourth coating according to (v) has a thickness in the range of 20 to 300 nm, preferably 20 to 180 nm, more preferably 20 to 130 nm, as determined according to high-resolution scanning electron microscopy.

[0189] 29. The effect pigment according to any of embodiments 25 to 28, wherein the fourth coating according to (v) further comprises SnO2.

[0190] 30. The effect pigment according to any of embodiments 25 to 29, wherein the effect pigment comprises four coating layers, wherein the first coating layer according to (ii) comprises SiO 2 , the second coating layer according to (iii) comprises TiO 2 , the third coating layer according to (iv) comprises SiO 2 and the fourth coating layer according to (v) comprises TiO 2 ; or

[0191] The first coating according to (ii) comprises SiO2, the second coating according to (iii) comprises TiO2; the third coating according to (iv) comprises SiO2 and the fourth coating according to (v) comprises Fe2O3; or

[0192] The first coating according to (ii) comprises SiO2, the second coating according to (iii) comprises Fe2O3; the third coating according to (iv) comprises SiO2 and the fourth coating according to (v) comprises TiO2; or

[0193] The first coating according to (ii) comprises SiO2, the second coating according to (iii) comprises Fe2O3; the third coating according to (iv) comprises SiO2 and the fourth coating according to (v) comprises Fe2O3.

[0194] 31. The effect pigment according to any of embodiments 1 to 30, having a Δ sparkle intensity ΔS_i determined according to Reference Example 2 in the range of 0.5 to 5.0, preferably 1.0 to 4.0, more preferably 2.0 to 3.0.

[0195] 32. A method for preparing an effect pigment, preferably an effect pigment according to any one of embodiments 1 to 31, the method comprising:

[0196] (a) providing a transparent plate-like substrate having a refractive index in the range of 1.0-2.1;

[0197] (b) applying a first composition comprising at least one first metal oxide precursor selected from Si, Al, Mg, Zn and mixtures thereof on the transparent plate-like substrate to obtain a first uncalcined coating;

[0198] (c) calcining the transparent plate-like substrate and the first uncalcined coating in air at a temperature in the range of 650-950° C. and normal pressure for a duration of 5-60 minutes;

[0199] (d) obtaining an effect pigment comprising, on the transparent plate-like substrate, a first coating comprising at least one first metal oxide selected from the group consisting of SiO2, Al2O3, MgO, ZnO and mixtures thereof, the first coating having a refractive index of at most 0.30 of the transparent plate-like substrate;

[0200] The coating according to (b) is performed by one or more of aqueous precipitation, sol-gel coating and chemical vapor deposition.

[0201] 33. The method of embodiment 32, wherein before (c), the method further comprises:

[0202] (bi) applying a second composition comprising at least one second metal oxide precursor selected from Ti, Fe and a mixture thereof on the first coating to obtain a second uncalcined coating.

[0203] 34. The method of embodiment 32 or 33, wherein before (bi), the transparent plate-like substrate and the first uncalcined coating obtained according to (b) are calcined in air at a temperature of 650-950° C. and normal pressure for a duration of 5-60 minutes.

[0204] 35. The method according to any one of embodiments 32-34, further comprising:

[0205] (b.ii) applying at least one further composition onto the second coating obtained according to (b.1), wherein if at least two further compositions are applied, they are preferably applied one after the other, thereby obtaining at least a third coating on the second coating and a fourth coating on the third coating, wherein more preferably before applying the further composition onto a given coating, the coating is calcined.

[0206] 37. An effect pigment obtainable or obtained by the method according to any one of embodiments 32 to 36.

[0207] 38. Use of the effect pigment according to any of embodiments 1 to 31 and 37 as a component of and / or for the preparation of one or more of printing inks, paints and coating compositions.

[0208] 39. The use according to embodiment 38, wherein the coating composition is an automotive coating composition.

[0209] 40. A method of preparing one or more of a printing ink, a paint and a coating composition, comprising using the effect pigment according to any one of embodiments 1 to 31 and 37 as a component.

[0210] 41. The method of embodiment 40, wherein the coating composition is an automotive coating composition.

[0211] 42. A printing ink, paint and / or coating composition comprising or consisting of an effect pigment according to any of embodiments 1 to 31 and 37.

[0212] 43. Use of the effect pigment according to any of embodiments 1 to 31 and 37 as a component for enhancing sparkle effects in printing inks, paints and coating compositions.

[0213] 44. A method of enhancing the sparkle effect of one or more of printing inks, paints and coating compositions, comprising using the effect pigment according to any one of embodiments 1 to 31 and 37 as a component.

[0214] The invention has been described in detail, including preferred embodiments thereof. However, it will be appreciated that those skilled in the art, upon consideration of this disclosure, may make modifications and / or improvements to the invention that fall within the scope and spirit of the invention.

[0215] The present invention is further described by the following non-limiting examples, which further illustrate the present invention and are not intended, nor should they be construed, to limit the scope of the present invention.

[0216] Reference Examples

[0217] Reference Example 1 (Determination of Dv50)

[0218] Dv50 values ​​were determined using a Malvern Mastersizer equipment.

[0219] Reference Example 2 (Determination of Sparkle Value and CIELab Value)

[0220] The sparkle grade S_G represents the total sparkle of the pigment and is a mathematical combination of the S_i and S_a values. S_i represents the sparkle intensity and relates to the intensity of the detected light. S_a represents the sparkle area and relates to the number of light reflections per surface unit.

[0221] The sparkle rating S_G as well as the S_i and S_a and the h, C*, L*, ΔH*, ΔC*, ΔL* and ΔE* values ​​of the pigments of the invention were determined using a BYK-mac device (from BYK Gardner) at an angle of 15° and -15°. To determine the sparkle and CIELab data of the pigments, a dried and cured coating film obtained with a 90:10 black reduction was applied and measured as follows: The pigment (as a 50:50 slurry of the pigment in a solvent that is part of the clearcoat) was incorporated into a conventional solventborne medium solids cellulose acetate butyrate (CAB) / polyester clearcoat (pigment / binder 20 / 100) at a total color level of 5% by weight (based on the total weight of the wet clearcoat) by stirring until the pigment was finally dispersed. The finished clearcoat was applied to an aluminum panel by pneumatic spraying at a wet film thickness of about 150-160 μm and then dried at room temperature. After drying, the basecoat was topcoated with a 1K clearcoat (clearcoat containing blocked isocyanate, acrylic polymer with OH functional groups, melamine crosslinker and other additives such as UV absorber, antioxidant and leveling agent), dried and cured at 135° C. After curing, the basecoat was about 20 μm thick and the clearcoat was about 40 μm thick.

[0222] Reference Example 3 (Determination of the latter)

[0223] The thickness was determined using a cross-cut of pigment in the resin. The cross-cut was obtained by using wet diamond cutting and mechanical polishing. The thickness of the obtained cross-cut was determined using high-resolution scanning electron microscopy and EDS observation. Equipment SEM (JSM7800F, JOEL) and EDS (X-MAX80mm2, Oxford) were used.

[0224] Examples and Comparative Examples

[0225] Example 1

[0226] A 10% aqueous slurry containing 200 g of synthetic mica flakes (fluorphlogopite, average particle size (Dv50) ~ 20 microns) was stirred at room temperature. The pH of the slurry was adjusted to 1.4 with 28% HCl, and then 22.4 g of 20% SnCl4.5H2O (an aqueous solution containing 20 wt% SnCl4.5H2O and 80 wt% water) was added at a rate of 1.0 g / min, while maintaining the pH at 1.40 by adding 10% NaOH. The slurry was stirred for 30 minutes and then heated to 74°C. At this temperature, the pH of the slurry was slowly raised to 7.8 with 35% NaOH. Then 900 g of 20% Na2SiO3.5H2O (an aqueous solution containing 20 wt% Na2SiO3.5H2O and 80 wt% water) was added at 2.0 g / min, while maintaining the pH at 7.80 by adding 28% HCl. After the addition was complete, the pH of the slurry was slowly adjusted to 1.4 with 28% HCl, and then after stirring for 1 hour, 22.4 g of 20% SnCl4.5H2O (an aqueous solution containing 20 wt% SnCl4.5H2O and 80 wt% water) was added at a rate of 1.0 g / min, while maintaining the pH at 1.4 by adding 10% NaOH. The slurry was stirred for 30 minutes, and then 475 g of 40% TiCl4 (an aqueous solution containing 40 wt% TiCl4 and 60 wt% water) was added at a rate of 1.25 g / min, while maintaining the pH at 1.4 by adding 35% NaOH. At the desired pearlescent color, 50 mL of the slurry was filtered, the filter cake was washed with water and dried at 120° C. for 30 minutes, and calcined at 850° C. for 20 minutes. The sample was scraped to measure the color. The first coating comprising SiO2 had a thickness of 50 nm and the second coating comprising TiO2 had a thickness of 30-50 nm. The resulting pigments have a pearlescent hue with improved sparkle.

[0227] Example 2

[0228] Example 2 The same procedure as in Example 1 was followed, except that 1100 g of the 20% Na2SiO3.5H2O (an aqueous solution containing 20 wt% SnCl4.5H2O and 80 wt% water) and 455 g of 40% TiCl4 (an aqueous solution containing 40 wt% TiCl4 and 60 wt% water) were added. The first coating layer containing SiO2 had a thickness of 50 nm and the second coating layer containing TiO2 had a thickness of 30-50 nm. The resulting pigment had a pearlescent hue with improved sparkle.

[0229] Example 3

[0230] Example 3 The same procedure as in Example 1 was followed, except that 1300 g of the 20% Na2SiO3.5H2O (an aqueous solution containing 20 wt% SnCl4.5H2O and 80 wt% water) and 480 g of 40% TiCl4 (an aqueous solution containing 40 wt% TiCl4 and 60 wt% water) were added. The first coating layer containing SiO2 had a thickness of 50-100 nm and the second coating layer containing TiO2 had a thickness of 30-50 nm. The resulting pigment had a pearlescent hue with improved sparkle.

[0231] Example 4

[0232] Example 4 The same procedure as in Example 1 was followed, except that 2000 g of the 20% Na2SiO3.5H2O (an aqueous solution containing 20 wt% Na2SiO3.5H2O and 80 wt% water) and 425 g of 40% TiCl4 (an aqueous solution containing 40 wt% TiCl4 and 60 wt% water) were added. The first coating layer comprising SiO2 had a thickness of 100 nm and the second coating layer comprising TiO2 had a thickness of 30-50 nm. The resulting pigment had a golden hue with improved sparkle.

[0233] Comparative Example 1

[0234] Comparative Example 1 The same procedure as in Example 1 was followed, except that neither 20% Na2SiO3.5H2O nor the second 20% SnCl4.5H2O was added. Only the first 11.2 g of 20% SnCl4.5H2O and 555 g of 40% TiCl4 (an aqueous solution containing 40% by weight of TiCl4 and 60% by weight of water) were used as in conventional pearlescent effect pigments. 100 mL of the slurry was filtered, the filter cake was washed with water and calcined at 850° C. for 20 minutes. The sample was drawn down to measure the color. The resulting pigment had a pearlescent color with poor sparkle.

[0235] Example 5

[0236] Example 5 The same procedure as in Example 4 was followed, except that 20% Na2SiO3.5H2O (an aqueous solution containing 20% ​​by weight of Na2SiO3.5H2O and 80% by weight of water) was added at 3.0 g / min and 890 g of 40% TiCl4 (an aqueous solution containing 40% by weight of TiCl4 and 60% by weight of water) was added until the desired gold hue was achieved. The calcination temperature was 825° C. The first coating layer comprising SiO2 had a thickness of 100 nm. The resulting pigment had a blue hue with improved sparkle.

[0237] Comparative Example 2

[0238] Comparative Example 2 The same procedure as Comparative Example 1 was followed, except that 970 g of 40% TiCl4 (an aqueous solution containing 40% by weight of TiCl4 and 60% by weight of water) was used as in conventional gold-tone effect pigments. The calcination temperature was 825° C. The resulting pigment had a poorly sparkling gold hue.

[0239] Example 6

[0240] Example 6 The same procedure as in Example 4 was followed, except that 20% Na2SiO3.5H2O (an aqueous solution containing 20% ​​by weight of Na2SiO3.5H2O and 80% by weight of water) was added at 3.0 g / min and 1465 g of 40% TiCl4 (an aqueous solution containing 40% by weight of TiCl4 and 60% by weight of water) was added until the desired blue hue was achieved. The calcination temperature was 825° C. The first coating layer containing SiO2 had a thickness of 100 nm. The resulting blue interference pigment showed a stronger sparkle than Comparative Example 3.

[0241] Comparative Example 3

[0242] Comparative Example 3 The same procedure as Comparative Example 1 was followed, except that 1480 g of 40% TiCl4 (an aqueous solution containing 40 wt. % TiCl4 and 60 wt. % water) was used as in conventional blue-tone effect pigments. The calcination temperature was 825° C. The resulting pigment had a blue hue with poor sparkle.

[0243] To determine the sparkle and CIELab values ​​of the pigments prepared in the above examples, the dried and cured coating films diluted with 90:10 black were applied and measured as follows: the pigment (as a 50:50 slurry of the pigment in a solvent that is part of the clearcoat) was incorporated into a conventional solventborne medium solids cellulose acetate butyrate (CAB) / polyester clearcoat (pigment / binder 20 / 100) at a total color level of 5 wt% (based on the total weight of the wet clearcoat) by stirring until the pigment was finally dispersed. The finished clearcoat was applied to an aluminum plate by pneumatic spraying at a wet film thickness of about 150-160 μm and then dried at room temperature. After drying, the basecoat was topcoated with a 1K clearcoat (a clearcoat containing blocked isocyanate, an acrylic polymer with OH functional groups, a melamine crosslinker and other additives such as UV absorbers, antioxidants and leveling agents), dried and cured at 135° C. After curing, the basecoat was about 20 μm thick and the clearcoat was about 40 μm thick. The sparkle effect of these plates was measured using a BYK-mac device (from BYK Gardner). The sparkle values ​​(S_a, S_i and S_G) reported in Table 3 are at an angle of 15° and clearly show the enhanced sparkle of the examples compared to the comparative examples.

[0244] Table 3. Sparkle values ​​measured at 15°

[0245]

[0246] Table 4. Measured CIELab values

[0247]

[0248]

[0249] References:

[0250] -US10214651B1

[0251] -US7699927B1

[0252] -CN108165053A

[0253] -WO2008120846A1

[0254] -US7485183B1

[0255] -US8883879B1

[0256] -US8500901B1

[0257] -US10597544B1

[0258] -US20130164356B1

[0259] -US11180659B1

[0260] -US10647861B1

[0261] -EP2917285A1

[0262] -US8529876B1

[0263] -US20080279796B1

[0264] -US8268069B1

[0265] -US20200369891B1

[0266] -IN-240942

[0267] -US20170105915A1

[0268] -US20210115260A1

[0269] -CN211416537U

[0270] -US20070298149B1

[0271] -EP3596170A1

[0272] -US20210087403A1

[0273] -CN109181364A

[0274] -US20200339820A1

Claims

1. An effect pigment composition comprising one or more transparent plate-like substrates, said substrates comprising a near-refractive index coating matched to said substrates.

2. The composition of claim 1, wherein the substrate is selected from the group consisting of mica, glass flakes, SiO2, Al2O3, BiOCl, kaolin, ZnO, BN, perlite and mixtures thereof, preferably mica, glass flakes, perlite and mixtures thereof, more preferably the substrate comprises mica, more preferably mica.

3. The composition of claim 2, wherein the transparent plate-like substrate is mica selected from muscovite (natural mica) and fluorophlogopite (synthetic mica), preferably the substrate comprises fluorophlogopite, more preferably fluorophlogopite.

4. A composition according to any preceding claim, wherein the refractive index of the transparent plate-like substrate is in the range of 1.0 to 2.1, preferably 1.2 to 2.0, more preferably 1.3 to 1.9, more preferably 1.4 to 1.

8.

5. The composition of any preceding claim, wherein the near-refractive index coating has a refractive index in the range of 1.0-2.1, preferably 1.2-2.0, more preferably 1.3-1.9, more preferably 1.4-1.

8.

6. The composition of any preceding claim, wherein the near-refractive index coating has a refractive index within 0.3 of the substrate, preferably in the range of 0.0-0.29, more preferably 0.0-0.20, more preferably 0.0-0.

15.

7. The composition of any preceding claim, wherein the near-refractive index coating has a thickness in the range of 30-170 nm, preferably 40-160 nm, more preferably 50-150 nm.

8. The composition of any preceding claim, wherein 90-100 wt. %, preferably 95-100 wt. %, more preferably 98-100 wt. %, more preferably 99-100 wt. % of the near-refractive index coating consists of SiO2, Al2O3, MgO, ZnO and mixtures thereof.

9. The composition of any preceding claim, wherein the near-refractive index coating comprises a material, wherein the material is selected from SiO2, Al2O3, MgO, ZnO and mixtures thereof, preferably SiO2, Al2O3 and mixtures thereof, more preferably the material for the near-refractive index coating comprises SiO2, more preferably SiO2.

10. The composition of any preceding claim, wherein the near-refractive index coating is comprised of two metal oxides, A and B, that are mixed to produce the near-refractive index coating, wherein the refractive index of the near-refractive index coating is determined using the formula: n=X A ·n A +X B ·n B , Where n is the resulting refractive index of the near-refractive index coating; X A is the molar fraction of metal oxide A; n A is the refractive index of metal oxide A; X B is the molar fraction of metal oxide B and n B is the refractive index of metal oxide B.

11. The composition of any preceding claim, wherein the substrate has a Dv50 in the range of 5-100 microns, preferably the substrate has a Dv50 less than 30 microns, more preferably the substrate has a Dv50 in the range of 5-30 microns, more preferably 5-25 microns.

12. The composition of any preceding claim, further comprising a combination of subsequent optical layers.

13. The composition of claim 12, wherein the subsequent optical layer is selected from the group consisting of TiO2, Fe2O3, TiO2 / Fe2O3, TiO2 / SiO2 / TiO2, TiO2 / SiO2 / Fe2O3, Fe2O3 / SiO2 / TiO2 and Fe2O3 / SiO2 / Fe2O3, preferably the subsequent optical layer is selected from the group consisting of TiO2 and Fe2O3, more preferably the subsequent optical layer comprises a TiO2 layer, more preferably a TiO2 layer.

14. The composition of claim 12 or 13, wherein each subsequent optical layer has a thickness in the range of 20-300 nm, preferably 20-180 nm, more preferably 20-130 nm.

15. A composition according to any preceding claim, having a delta sparkle intensity ΔS_i in the range of 0.5-5.0, preferably 1.0-4.0, more preferably 2.0-3.

0.

16. The composition of any preceding claim, wherein the near-refractive-index coating further comprises SnO2.

17. The composition of any preceding claim, wherein the near-refractive index coating is applied by a process selected from the group consisting of aqueous precipitation, sol-gel, and chemical vapor deposition.

18. The composition of any preceding claim, wherein the applied near-index coating is calcined prior to applying additional optical layers.

19. A printing ink, paint or coating composition comprising the composition of any one or more of claims 1 to 18.

20. The printing ink, paint or coating composition of claim 19 which is an automotive coating.

21. A method of preparing a composition according to any one of claims 1 to 18, wherein the near-refractive index coating is applied to the transparent plate-like substrate by a method selected from aqueous precipitation, sol-gel and chemical vapor deposition.

22. The method of claim 21, wherein the near-refractive index coating is fired prior to applying a combination of subsequent optical layers.

23. A method of enhancing the sparkle of effect pigments based on a transparent plate-like substrate, comprising applying a near-refractive index coating matched to the substrate.

24. The method of claim 23, wherein the substrate is selected from the group consisting of mica, glass flakes, SiO2, Al2O3, BiOCl, kaolin, ZnO, BN, perlite and mixtures thereof, preferably mica, glass flakes, perlite and mixtures thereof, more preferably the substrate comprises mica, more preferably mica.

25. The method of claim 24, wherein the transparent plate-like substrate is a mica selected from muscovite (natural mica) and fluorophlogopite (synthetic mica), preferably the substrate comprises fluorophlogopite, more preferably fluorophlogopite.

26. The method of claim 23, wherein the refractive index of the transparent plate-like substrate is in the range of 1.0-2.1, preferably 1.2-2.0, more preferably 1.3-1.9, more preferably 1.4-1.

8.

27. The method of claim 23, wherein the refractive index of the near-refractive index coating is in the range of 1.0-2.1, preferably 1.2-2.0, more preferably 1.3-1.9, more preferably 1.4-1.

8.

28. The method of claim 23, wherein the near-refractive index coating has a refractive index within 0.3 of the substrate, preferably in the range of 0.0-0.29, more preferably 0.0-0.20, more preferably 0.0-0.

15.

29. The method of claim 23, wherein the near-refractive index coating has a thickness in the range of 30-170 nm, preferably 40-160 nm, more preferably 50-150 nm.

30. The method of claim 23, wherein 90-100 wt. %, preferably 95-100 wt. %, more preferably 98-100 wt. %, and more preferably 99-100 wt. % of the near-refractive-index coating consists of SiO2, Al2O3, MgO, ZnO, and mixtures thereof.

31. The method of claim 23, wherein the near-refractive index coating comprises a material, wherein the material is selected from SiO2, Al2O3, MgO and mixtures thereof, preferably SiO2, Al2O3 and mixtures thereof, more preferably the material for the near-refractive index coating comprises SiO2, more preferably SiO2.

32. The method of claim 23, wherein the near-refractive index coating is comprised of two metal oxides, A and B, that are mixed to produce the near-refractive index coating, wherein the refractive index of the near-refractive index coating is determined using the formula: n=X A ·n A +X B ·n B , Where n is the resulting refractive index of the near-refractive index coating; X A is the molar fraction of metal oxide A; n A is the refractive index of metal oxide A; X B is the molar fraction of metal oxide B and n B is the refractive index of metal oxide B.

33. The method of claim 23, wherein the substrate has a Dv50 in the range of 5-100 microns, preferably the substrate has a Dv50 less than 30 microns, more preferably the substrate has a Dv50 in the range of 5-30 microns, more preferably 5-25 microns.

34. The method of claim 23, further comprising a combination of subsequent optical layers.

35. The method of claim 23, wherein the subsequent optical layer is selected from the group consisting of TiO2, Fe2O3, TiO2 / Fe2O3, TiO2 / SiO2 / TiO2, TiO2 / SiO2 / Fe2O3, Fe2O3 / SiO2 / TiO2 and Fe2O3 / SiO2 / Fe2O3, preferably the subsequent optical layer is selected from the group consisting of TiO2 and Fe2O3, more preferably the subsequent optical layer comprises a TiO2 layer, more preferably a TiO2 layer.

36. The method of claim 23, wherein each subsequent optical layer has a thickness in the range of 20-300 nm, preferably 20-180 nm, more preferably 20-130 nm.

37. The method of claim 23, having a Δ flash intensity ΔS_i in the range of 0.5-5.0, preferably 1.0-4.0, more preferably 2.0-3.

0.

38. The method of claim 23, wherein the near-refractive-index coating further comprises SnO2.

39. The method of claim 23, wherein the near-refractive index coating is applied by a method selected from the group consisting of aqueous precipitation, sol-gel, and chemical vapor deposition.

40. The method of claim 23, wherein the applied near-index coating is fired prior to applying additional optical layers.

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