Radar-transparent and optically reflective semiconductor effect pigments

Abstract

Provided is an effect pigment that can provide a coating formulation and a paint having a wide optical versatility and effect and at the same time sufficient radar permeability to the coating industry. 【Solution means】A flaky effect pigment containing a single platelet as an optically active layer, the single platelet being made of a semiconductor material having a band gap in the range of 0.1 to 2.5 eV, and (a) Si (1-x) Ge x , 0 < x < 1.00, or (b) Si (1-y) Sn y , 0 < y < 0.90, or (c) Ge (1-z) Sn z , 0 < z ≦ 0.60, or (d) Si (1-m-n) Ge m Sn n , 0

Description

[Technical Field]

[0001] The present invention relates to effect pigments based on specific semiconductor platelets as the only optically active layer, to a method for their preparation, and to their use as radar-transparent effect pigments with attractive optical properties. [Background technology]

[0002] Aluminum's high surface reflectivity results from its high electrical conductivity, which results in a high surface plasma frequency. If the frequency of light incident on a surface is lower than the surface plasma frequency, the incident light is efficiently reflected from the surface. In aluminum, the surface plasma frequency can reflect light frequencies ≥ near-UV light, which includes visible light, IR, microwaves, and radio waves. Therefore, aluminum, and many other metals, exhibit high reflectivity over a wide wavelength range. Unfortunately, the same effects that govern visible light reflection also affect the reflection of IR, microwave, and RADAR wavelengths. Therefore, aluminum and other metal platelets have poor RADAR transparency, yet are used worldwide as standard effect pigments for metallic effects in the visible range, particularly in automotive coatings.

[0003] The use of dielectrics such as pearlescent pigments together with fine aluminum flakes to thereby increase the RADAR transparency of the composite is disclosed in WO2020 / 208134A1, US2010 / 0022696A1, or WO2021 / 030197A1.

[0004] In this case, metal flakes, and typically aluminum flakes, are still present in the coating and the radar attenuation needs to be balanced with the expected optical properties of the final coating. In many cases, the radar attenuation is still too high and / or certain colors cannot be achieved.

[0005] US2002 / 0041047A1 focuses on the efficient production of thin metal flakes by PVD processes. It mainly deals with aluminum flakes, but in one example also discloses Si flakes with a thickness of 35 nm.

[0006] Dielectrics are non-electrically conductive and therefore do not suffer from the same high surface plasma frequency reflectivity problem of aluminum. Dielectrics achieve their reflectivity and opacity through Fresnel reflection, and the reflectivity equation for the top single surface is: r top =(n mat -n med1 ) / (n mat +n med1 ) It is defined as The reflectance equation for the bottom surface (referring to the incident light above) is: r bottom =(n med2 -n mat ) / (n med2 +n mat ) It is defined as r top is the reflectance amplitude from the top surface, and r bottom is the reflectance amplitude from the bottom surface, and n mat is the refractive index of the material, and n med1 is the refractive index of the medium above the material, and n med2 is the refractive index of the medium below the material (above the incident light n med1 ).

[0007] The reflection intensity (R) is R=r 2 It is defined as:

[0008] binder Complex So typically, 1.35 <n med1 =n med2 <1.6. Dielectric materials, such as TiO2 and SiO2, typically have n 誘電体 ≦2.7, the upper limit of the total reflectance from both surfaces (considering constructive interference) is <25%. Therefore, dielectric pigments are suitable for particle sizes < <Iレーダー While it exhibits high RADAR transparency when homogenized, its applications are limited due to its low optical reflectivity and low opacity (hiding power).

[0009] Semiconductors typically have high n across the spectral range. mat shows an increased n above the band gap mat For example, silicon has an n of ~3.4 at λ ~ 4000 nm. semi shows a peak n of ~6.7 at λ~370 nm. semi This relationship applies to most elemental and compound semiconductors. The same condition as for the dielectrics (1.35 <n med1 =n med2 <1.6), but with n of ~5.0 in the visible range semi With this, a total reflectance of >50% (considering constructive interference) can be achieved.

[0010] The use of semiconducting films such as silicon, germanium or alloys thereof is known in the literature for the production of random systems for the development of autonomous vehicles, examples of which are disclosed in WO2021 / 018422A1 or US2010 / 0207842A1. Summary of the Invention [Problem to be solved by the invention]

[0011] However, there is also an urgent need to develop effect pigments that will enable the coatings industry to provide coating formulations and paints with a wide range of optical versatility and effects, and at the same time, with sufficient radar transparency.

[0012] In particular, there is a need for new effect pigments that have a metallic appearance but much higher radar transparency than mixtures of metallic effect pigments and dielectric pigments. They need to be readily available and have various color tones. Particularly desired are silver appearance effect pigments, because they have the highest attractiveness, especially in the automotive market.

[0013] The pigments need to have good hiding power, metallic gloss, and high metallic flop.

Means for Solving the Problems

[0014] These objects are solved by providing a flaky effect pigment comprising a single platelet of a semiconductor material having a band gap in the range of 0.1 to 2.5 eV and having the following average atomic composition as an optically active layer: (a) Si (1-x) Ge x , 0 < x < 1.00, or (b) Si (1-y) Sn y , 0 < y < 0.90, or (c) Ge (1-z) Sn z , 0 < z ≤ 0.60, or (d) Si (1-m-n) Ge m Sn n , provided that 0 < m < 1.00, 0 < n < 1.00, provided that x < 1.00; y < 1.00, z < 1.00 and m + n < 1.00.

Embodiments for Carrying Out the Invention

[0015] More preferred embodiments are disclosed in claims 2 to 11.

[0016] The object is further solved by providing a method for producing an effect pigment comprising the following steps: (a) Providing a flexible substrate coated with a release agent, (b) Under ultra-high vacuum conditions, depositing a semiconductor material having a bandgap in the range of 0.1 to 2.5 eV onto a flexible substrate (a), (c) Separating the semiconductor film from the flexible substrate in a suitable solvent and particle-milling in a dispersion to obtain semiconductor flakes, (d) Separating the semiconductor flakes from the solvent, (e) Optionally, performing further steps, such as further size-classifying the semiconductor flakes or dispersing the semiconductor flakes in a different solvent, and further surface treatment steps.

[0017] Further preferred embodiments are disclosed in claims 13 to 14.

[0018] Finally, the object of the present invention is solved by providing a coating Complex comprising a binder and flaky effect pigments.

[0019] In this invention, a single platelet semiconductor has the following average atomic composition: (a) Si (1-x) Ge x , 0 < x < 1.00, or (b) Si (1-y) Sn y , 0 < y < 0.90, or (c) Ge (1-z) Sn z , 0 < z ≦ 0.60, or (d) Si (1-m-n) Ge m Sn n , 0 < m < 1.00, 0 < n < 1.00, where x < 1.00; y < 1.00, z < 1.00 and m + n < 1.00.

[0020] x, y, n, and m are mole fractions. In a further preferred embodiment, the single platelet semiconductor according to (a) has a composition of 0.01 < x < 0.9, more preferably 0.02 ≦ x ≦ 0.8, and most preferably 0.05 ≦ x ≦ 0.65. These materials are alloys of silicon and germanium. Germanium brings about an interesting color effect because this material is absorptive in the visible wavelength region. This also increases the opacity compared to pure silicon flakes. Due to the high cost of this material, the germanium content is preferably as low as possible.

[0021] In a further preferred embodiment, the single platelet semiconductor according to (b) has a composition of 0.02 ≦ y ≦ 0.75, more preferably 0.05 ≦ y ≦ 0.55. These materials are alloys of silicon and tin.

[0022] In a further preferred embodiment, the single platelet semiconductor according to (c) has a composition of 0.02 ≦ z ≦ 0.5, more preferably 0.05 ≦ z ≦ 0.4. These materials are alloys of germanium and tin.

[0023] In a further preferred embodiment, the single platelet semiconductor according to (d) has a composition characterized by 0.02 ≦ m ≦ 0.8 and 0.02 ≦ n ≦ 0.75, more preferably a composition characterized by 0.05 ≦ m ≦ 0.65 and 0.05 ≦ n ≦ 0.55.

[0024] The platelet semiconductor particles may further contain normal impurities generated during the manufacture of the material, for example, they may contain carbon, nitrogen, or oxygen. These materials are not included in the above formula.

[0025] Impurities of other metals or other semiconductor materials not contained in the above formula are typically less than 0.1% by weight of the platelet semiconductor material, preferably less than 0.05% by weight, more preferably less than 0.005% by weight, and these are also not included in the above formula.

[0026] Platelet semiconductor particles may further contain a certain amount of oxygen due to surface oxidation. For example, platelet alloy semiconductor flakes may be oxidized on their surface. This type of oxygen is not included in the formula for clarity. Preferably, platelet semiconductor particles do not have detectable amounts of oxygen inside.

[0027] In a preferred embodiment, the band gap of the flake effect pigment is in the range of 0.2 to 1.4 eV, more preferably in the range of 0.4 to 1.2 eV, such band gaps being typical for semiconductor materials.

[0028] The semiconductor platelets have a solid structure and have low or no porosity within their internal structure. The porosity determined by mercury porosity measurement is essentially zero or cannot be determined at all due to the absence of voids. The effect pigments are preferably produced by PVD methods. Their major surfaces (top and bottom) are relatively flat and smooth, as is typical for PVD effect pigments. Such a smooth structure and the absence of detectable internal voids allow the platelets to function at optimum reflectivity.

[0029] Due to the high refractive index of these materials in the visible wavelength range, platelet semiconductor particles exhibit relatively high reflectance. Depending on the thickness of the semiconductor platelets, different colors can occur.

[0030] Therefore, the average thickness of a single semiconductor platelet, t a teeth 、5 ~160nm range 、good Preferably it is in the range of 10 nm to less than 140 nm, most preferably in the range of 15 to 130 nm.By "average thickness" is meant the arithmetic mean of the thickness of the pigment sample.

[0031] Average thickness t of 160 nm aAbove 5 nm, the semiconductor platelets may not be well oriented in the final coating system, significantly reducing hiding power. a In this case, the platelets can be mechanically unstable and difficult to reproduce with sufficient quality.

[0032] t a The values ​​are determined by counting the thickness distribution of the platelets using SEM as described in WO2004 / 087816A2, except that the arithmetic mean is determined instead of the median value.

[0033] In a preferred embodiment, the flake-shaped effect pigments have an average thickness t of a single semiconductor platelet in the range of 12 to 40 nm, preferably in the range of 18 to 35 nm. a and has a silver appearance. Particularly preferred for such type of flake effect pigments are the above-mentioned Si-Ge or Si-Sn alloys.

[0034] What is meant by "silver appearance" or "neutral hue" in the present invention is a color-neutral saturation across all measurement angles (-15°, 15°, 25°, 45°, 75° and 110°) in the application of these effect pigments, which corresponds to a * value and b * This is achieved when the absolute values ​​of the values ​​are independently less than 6.5 units, more preferably less than 4.0 units, and most preferably less than 2.0 units. Preferably, the application as described in the experimental section for drawdown is used in this case.

[0035] In another preferred embodiment, the flake-shaped effect pigment has a median thickness h of a single semiconductor platelet in the range from more than 40 to 160 nm. 50 In this case, a * Value range and b * The absolute value of the value range is independently 6.5 units or greater in the CIELab color space.

[0036] Regarding the size and size distribution of the flake effect pigments, a size range typical for coatings in the automotive industry or industrial coatings is selected. Preferably, the flake effect pigments have a particle size distribution d 50 and is in the range of 2 to 100 μm, more preferably in the range of 5 to 40 μm, even more preferably in the range of 6 to 35 μm, and most preferably in the range of 7 to 30 μm.

[0037] Pigment size is typically expressed in terms of a quantile (d value) from the volume average particle size distribution, where the number indicates the proportion of particles smaller than a particular size contained in the volume average particle size distribution. For example, d 50 The value indicates the size below which 50% of the particles are smaller. These measurements are carried out by laser particle size distribution analysis using, for example, a particle size analyzer manufactured by Horiba (Horiba LA950 instrument). The measurements are carried out using the Fraunhofer approximation for an equivalent sphere and appropriate parameters according to information from the manufacturer.

[0038] d 10 The value characterizes the amount of fine particles and is typically in the range of 2 to 20 μm, preferably 4 to 15 μm.

[0039] d 90 The value characterizes the amount of coarse particles and typically ranges from 15 μm to 140 μm, preferably from 20 μm to 50 μm.

[0040] The width of the particle size distribution is (d 90 -d 10 ) / d 50 Preferably, this distance is 1.50 to 2.2, and more preferably 1.6 to 2.0.

[0041] Without intending to be limited by theory, the inventors believe that due to the particle size of effect pigments being much smaller than radar microwaves, the attenuation of radar waves is relatively lower than in a macroscopic film of a corresponding semiconductor material.

[0042] The flake effect pigments according to the invention preferably have a 50 / h 50 This is in the range of 30 to 2000, more preferably in the range of 40 to 1500, and most preferably in the range of 50 to 1000.

[0043] In the scope of the present invention, the only optically active layer of the flake-shaped effect pigments consists of the above-mentioned semiconductor platelets.Another advantage of these effect pigments compared to metal flakes, especially compared to the widely used aluminum flakes, is their excellent gassing stability.Usually, these platelets do not need to be coated with an additional corrosion protection layer.

[0044] However, in some cases such a coating may be necessary, and in many more cases a specific coating with an optically inactive material may be useful.

[0045] Thus, in a further embodiment, the single semiconductor platelet is further surrounded by a transparent, non-optically active metal oxide with a refractive index of n<1.8, preferably <1.6.

[0046] In the scope of the present invention, an optically inactive layer is meant to refer to a layer that reflects less than 20%, or preferably less than 10%, of incident light in the visible wavelength range. Additionally, this does not change the chroma response. In particular, the outer optically inactive layer, when used in nitrocellulose lacquers as described in the experimental section, shows a change in the chroma response of such coated effect pigments compared to the same layer stack effect pigments without the outer optically inactive layer, which is ΔC* 15° is ≦2.0 and / or ΔH * 15° is ≦10°, preferably ≦5° and / or ΔL * 15° is ≦10.

[0047] Typically, such inert layers have an average refractive index in the visible wavelength range of less than 1.7, more preferably less than 1.6. Typically, such inert layers have an optical density in the visible wavelength range of less than 34 nm, more preferably less than 32 nm. In this case, the refractive index refers to the literature bulk value of the respective material, rather than the effective refractive index of the layer.

[0048] In a preferred embodiment, the optically inactive layer surrounds essentially the entire semiconductor platelet and is comprised of a layer of Mo oxide, SiO2, Al2O3, BO3, or mixtures thereof. If not used to further enhance gassing stability, typical optically inactive layers are surface modifiers such as organofunctional silanes, titanates, aluminates, or zirconates, phosphate esters, phosphonate esters, phosphite esters, alcohol, or amine-based additives, and combinations thereof.

[0049] Such surface modifiers are used as top coatings to adjust the chemical compatibility of the effect pigments with the final application binder medium, as described, for example, in EP 1 084 198 A1. They can be coated directly onto the single semiconductor platelet pigment or directly onto the optically inactive layer.

[0050] The most preferred surface modifier is an organofunctional silane. In another preferred embodiment, the semiconductor platelet is first coated with a thin layer of SiO2, and then coated with a suitable surface modifier, most preferably an organofunctional silane. In this case, the SiO2 layer is mainly used to improve the adhesion of the organofunctional silane to the surface of the semiconductor platelet.

[0051] Suitable organofunctional silanes are commercially available, for example, manufactured by Evonik, Rheinfelden, Germany, and sold under the trade name "Dynasylan™". Further products can be purchased from OSi Specialties (Silquest™ silanes) or Wacker (Genosil™ silanes).

[0052] Examples of suitable organofunctional silanes are 3-methacryloxypropyltrimethoxysilane (Dynasylan MEMO), vinyltri(meth)ethoxysilane (Dynasylan VTMO or VTEO), 3-mercaptopropyltri(meth)ethoxysilane (Dynasylan MTMO or 3201), 3-glycidyloxypropyltrimethoxysilane (Dynasylan GLYMO), tris(3-trimethoxysilylpropyl)isocyanurate (Siquest Y-11597), gamma-mercaptopropyltrimethoxysilane (Silquest A-189), bis(3-triethoxysilylpropyl)polysulfide (Silquest A-1289), bis(3-triethoxysilyl)disulfide (Silquest A-1589), beta(3,4-epoxycyclohexyl)ethyltri-methoxysilane (Silquest A-186), gamma-isocyanatopropyl-trimethoxysilane (Silquest A-Link 35, Genosil GF40), (methacryloyloxymethyl)trimethoxysilane (Genosil XL 33), and (isocyanatomethyl)trimethoxysilane (Genosil XL43).

[0053] In one preferred embodiment, the organofunctional silane mixture modifying the SiO layer contains at least one aminofunctional silane. The aminofunctional group is a functional group capable of chemically interacting with most groups present in the binder. This interaction may involve covalent bonding, for example with isocyanate or carboxylate groups of the binder, or hydrogen bonding, for example with OH or COOR groups, or even ionic interactions. This is therefore very well suited for the chemical attachment of effect pigments to various binders.

[0054] The following compounds are preferably used for this purpose: Aminopropyltrimethoxysilane (Dynasylan AMMO), Aminopropyltriethoxysilane (Dynasylan AMEO), N-(2-aminoethyl) -3-Aminopropyltrimethoxysilane (Dynasylan DAMO), N-(2-aminoethyl)-3-aminopropyltriethoxysilane, triaminofunctional trimethoxysilane (Silquest A-1130), bis(gamma-trimethoxysilylpropyl)amine (Silquest A-1170), N-ethyl-gamma-aminoisobutyltrimethoxysilane (Silquest A-Link 15), N-phenyl-gamma-diaminopropyltrimethoxysilane (Silquest Y-9669), 4-amino-3,3-dimethylbutyltrimethoxysilane (Silquest Y-11637), (N-cyclohexylaminomethyl)triethoxysilane (Genosil XL 926), (N-phenylaminomethyl)trimethoxysilane (Genosil XL 973), and mixtures thereof.

[0055] Alternatively, pre-hydrolyzed and pre-condensed organofunctional silanes can be used, as described, for example, in EP 3080209 B1.

[0056] Method for producing flake effect pigments The method for manufacturing flaky effect pigments includes the following steps: (a) Providing a flexible substrate coated with a release agent; (b) Depositing, under ultra-high vacuum conditions, a semiconductor material having a bandgap in the range of 0.1 eV to 2.5 eV and having the following average atomic composition, onto the flexible substrate (a): (a) Si (1-x) Ge x , where 0 < x < 1.00, or (b) Si (1-y) Sn y , where 0 < y < 0.90, or (c) Ge (1-z) Sn z , where 0 < z ≤ 0.60, or (d) Si (1-m-n) Ge m Sn n , where 0 < m < 1.00, 0 < n < 1.00, provided that x < 1.00; y < 1.00, z < 1.00 and m + n < 1.00; (c) Removing the semiconductor film from the flexible substrate, and particle-milling in a dispersion medium to obtain semiconductor flakes; (d) Separating the semiconductor flakes from the solvent, and (e) Optionally performing further steps, such as subjecting the semiconductor flakes to further size classification, or dispersing the semiconductor flakes in a different solvent, and further surface treatment steps. <

[0057] Step (a): This step is carried out in essentially the same manner as known for the production of PVD metal pigments, especially aluminum effect pigments. The flexible substrate is usually a web made of a polymer, most preferably a PET polymer. Conventional release agents may be used. Typically, the release agent is a polymer, such as an acrylic, methacrylic, or polystyrene. Other organic materials may also be used, as described in US 2004 / 0131776 A1 or US 20100062244 A1.

[0058] In a preferred embodiment, step (b) is performed by a roll-to-roll process. In step (b), in one embodiment, a semiconductor alloy of a predetermined composition is used as a bulk material, which is evaporated by an appropriate means to generate respective gas molecules, which are then transferred to the delaminating flexible substrate under ultra-high vacuum conditions. In another embodiment, two or three suitable bulk semiconductor materials of predetermined purity are used, allowing their vapor clouds to overlap before reaching the substrate.

[0059] Step (b) may be carried out as an electron beam process, magnetron sputtering, resistive evaporation, or induction heating. Most preferred is the evaporation of the semiconductor bulk material by an electron beam process.

[0060] Steps (c), (d), and (e) are similarly well known.

[0061] Another embodiment of the present invention is a coating comprising a binder and the flake effect pigments of the present invention. Complex Regarding Binder Complex The coating may be acrylic, polyester, polyurethane, polyepoxide, and copolymers thereof. Complex is the basic coating for automobiles.

[0062] Such coatings ComplexAdditionally, it may further contain other pigments, such as color pigments, pearlescent pigments, or metallic effect pigments.

[0063] Furthermore, the coating Complex contains a solvent or a solvent mixture. Preferably, they are aqueous coatings Complex Additionaly, they may contain fillers or additives as is customary in the prior art.

[0064] The volume concentration of the effect pigment in such coatings is preferably 0.1 to 100%, more preferably 1 to 20%, and most preferably 1.5 to 15%.

[0065] Further aspect: The electromagnetic attenuation (att n ) at a specific wavelength directly attributable to the pigment or coating (pigment and binder) is calculated by subtracting the measured electromagnetic attenuation of the substrate or the substrate and binder from that of the complete coating containing the substrate, binder, and pigment. For simplicity, att Complex is here expressed in units of decibels (dB). The luminance-to-attenuation ratio is defined as L n 15 / att * where att n is the attenuation in dB at a specific electromagnetic frequency or frequency range, such as IR, microwave, and radio frequency. Further aspects of the effect pigments of the present invention are as follows: n Aspect 1: A coating having flaky pigments where the flaky pigment comprises a single platelet made of a semiconductor material having a band gap in the range of 0.1 to 2.5 eV and the following average atomic composition as an optically active layer: <关于“ Complex ”,这里似乎没有完整内容,无法准确翻译,保留原文 Complex where the flaky pigment comprises a single platelet made of a semiconductor material having a band gap in the range of 0.1 to 2.5 eV and the following average atomic composition as an optically active layer: <00关于“ ”,这里似乎没有完整内容,无法准确翻译,保留原文 (a) Si (1-x) Ge x , 0 < x < 1.00, or (b) Si (1-y) Sn <00000​​​​​z , 0 < z ≤ 0.60, or (d) Si (1-m-n) Ge m Sn n , 0 < m < 1.00, 0 < n < 1.00, provided that x < 1.00; y < 1.00, z < 1.00 and m + n < 1.00, Here, An attenuation of less than 5 dB, preferably less than 4 dB, most preferably less than 3 dB in the frequency range of 0.3 THz to 300 THz (IR) is attributed to the flaky pigment or the coating containing the flaky pigment. Coating Complex . Embodiment 2: Coating having a flaky pigment Complex wherein the flaky pigment or the coating containing the flaky pigment exhibits a luminance of more than 85 and a luminance-to-attenuation ratio of more than 15, preferably more than 25, most preferably more than 50 in the frequency range of 0.3 THz to 300 THz (IR). Coating Complex . Embodiment 3: Coating having a flaky pigment <​​​​​​​​​​​​​A coating to which attenuation in the frequency range of 23 to 79 GHz (RADAR, part of microwave), less than 3 dB, preferably less than 2 dB, most preferably less than 1 dB, is attributed to flaky pigments or a coating containing flaky pigments Complex . Aspect 6: A coating having flaky pigments Complex A coating in which flaky pigments or a coating containing flaky pigments exhibit a luminance of more than 85 and a luminance-to-attenuation ratio of more than 25, preferably more than 50, most preferably more than 100, in the frequency range of 23 to 79 GHz (RADAR, part of microwave) Complex . Aspect 7: A coating having flaky pigments Complex A coating to which attenuation in the frequency range of 0.3 MHz to 3 GHz (RF), less than 3 dB, preferably less than 2 dB, most preferably less than 1 dB, is attributed to flaky pigments or a coating containing flaky pigments Complex . Aspect 8: A coating having flaky pigments Complex A coating in which flaky pigments or a coating containing flaky pigments exhibit a luminance of more than 85 and a luminance-to-attenuation ratio of more than 25, preferably more than 50, most preferably more than 100, in the frequency range of 0.3 MHz to 3 GHz (RF) Complex . Aspect 9: A coating having flaky pigments Complex A coating in which the single small plate semiconductor has the following average atomic composition Complex :[[]] (a) Si (1-x) Ge x , 0.01 < x < 0.9, preferably 0.02 ≤ x ≤ 0.8, or (b) Si (1-y) Sn y , 0.02 ≤ y ≤ 0.75, or (c) Ge (1-z) Sn z, 0.02≦z≦0.5, or (d)Si (1-m-n) Ge m Sn n , 0.02≦m≦0.8, 0.02≦n≦0.75. Aspect 10: Coating with flaky pigment Complex wherein the single platelet semiconductor has an average atomic composition of: Complex : (a)Si (1-x) Ge x , 0.05≦x≦0.65, or (b)Si (1-y) Sn y , 0.05≦y≦0.55, or (c) Ge (1-z) Sn z , 0.05≦z≦0.4, or (d)Si (1-m-n) Ge m Sn n , 0.05≦m≦0.65, 0.05≦n≦0.55. [Example]

[0066] Comparative Example 1: Commercially available Metalure Liquid Black (Eckart GmbH) is a black PVD metallic effect pigment with high flop properties.

[0067] Comparative Example 2: Commercially available Metalure L-55700 (Eckart GmbH), which is a standard PVD aluminum effect pigment.

[0068] Example 1: Silicon-germanium composite The silicon and germanium blend was deposited onto a 30 cm wide clear polyester film coated with a release agent using e-beam PVD deposition. The e-beam source was positioned 36 cm below the web during the process, and conditions were adjusted to achieve a silver color for the final pigment. The e-beam source accelerating voltage was held at a constant 10 kV throughout operation.

[0069] The material obtained in Example 1 was completely removed from the polyester film and homogenized to obtain a particle size (D 50 The pigment was prepared at 10 wt.% non-volatile content (NVM) in propyl glycol methyl ether acetate. The average particle thickness, t a is 23 + / - 3 nm. The elemental silicon:germanium atomic ratio determined from energy dispersive spectroscopy is 45:55.

[0070] Pigment samples were adjusted to 5% NVM with propyl glycol methyl ether acetate for spraying in a Deltron DBC500 Color Blender. Spray ink formulations were used to achieve a target pigment volume concentration of approximately 1.8-2.4%. Samples were applied in duplicate to achieve full coverage within 1-2 coats across polyester film and ABS plastic substrates. Panels were allowed to dry at ambient temperature for approximately 30 minutes between coats.

[0071] Gloss data was obtained using a BYK Micro Tri-gloss instrument. Additional optical data was obtained using a BYK Mac instrument. Optical data was obtained on polyester film on both the front (coated) and back sides of the film. Flop was calculated according to the following conventional formula: Flop Index = 2.69x(L* 15° -L* 110° ) 1.11 / L* 45° 0.86

[0072] The results of these measurements are summarized in Tables 1a-d below.

[0073] Tables 1a-d: Optical data obtained from the silicon germanium alloy effect pigment of Example 1 at different binder:pigment ratios and different substrates.

[0074] [Table 1a]

[0075] [Table 1b]

[0076] [Table 1c]

[0077] [Table 1d]

[0078] Example 2: Silicon-germanium pigment to binder ratio change The silicon and germanium formulation was deposited onto a 30 cm wide clear polyester film coated with a release agent using e-beam PVD deposition. The e-beam source was positioned 36 cm below the web during the process, and conditions were adjusted to obtain a silver color for the final pigment. The e-beam source accelerating voltage was held constant at 10 kV throughout operation.

[0079] All of the materials obtained in Example 2 were peeled from the polyester film and homogenized to obtain particles with a particle size of ∼14 μm (d 50 The pigment was prepared at 10 wt% non-volatile content (NVM) in propyl glycol methyl ether acetate. The average particle thickness t obtained via SEM analysis a is 29 + / - 3 nm. The elemental silicon:germanium atomic ratio determined from energy dispersive spectroscopy is 47:53.

[0080] A spray application ladder was designed and implemented. Multiple spray inks were blended to achieve calculated pigment volume concentrations ranging from 3 to 61% using a Deltron DBC500 Color Blender. Metal content was held constant throughout all ink formulations. Samples were applied in duplicate across ABS panel substrates. The entirety of each ink was applied in a single coat, thereby maintaining uniform metal distribution across all panels. Selected panels from each set were clearcoated with Deltron DC4000 and subjected to an additional 60-minute forced dry at 60°C. Between coats, the panels were allowed to dry at ambient temperature for approximately 30 minutes.

[0081] Gloss data was obtained using a BYK Micro Tri-gloss instrument. Additional optical data was obtained using a BYK Mac colorimeter. The results of these measurements are shown in Table 2 below.

[0082] Table 2a, b and c: Gloss, Flop, L for Example 3 at different binder:pigment ratios * , a * , and b * value

[0083] [Table 2a]

[0084] [Table 2b]

[0085] [Table 2c]

[0086] The effect pigment of this example exhibits a relatively neutral color tone, has a high flop value and is observed as an attractive effect pigment with a metallic appearance.

[0087] Increasing the binder / pigment ratio tends to reduce flop and gloss values ​​because, in this case, at reduced binder concentration, the system dries and there is less space between the flakes, which ensures that the pigment is better oriented to the substrate in a flat / parallel position, resulting in high reflectivity.

[0088] Example Group 3: SiSn Additional samples of silicon alloy flakes were produced according to Example 2, except that tin was used instead of germanium as the alloy material. Three experiments were performed under different conditions, resulting in different alloy flake compositions and thicknesses. The Si:Sn composition and flake thickness were varied and confirmed by SEM analysis, which is shown in Table 4. Oxygen content was excluded from this analysis.

[0089] [Table 3]

[0090] Spray inks were formulated using a Deltron DBC500 Color Blender with the binder:pigment ratios shown in Table 4. Metal content was held constant throughout all ink formulations. Samples were applied in duplicate across ABS panel substrates. The entirety of each ink was applied in a single coat to maintain uniform metal distribution across all panels. Selected panels from each set were clearcoated with Deltron DC4000 and subjected to an additional 60 minutes of forced drying at 60°C. Between coats, panels were allowed to dry at ambient temperature for approximately 30 minutes.

[0091] Gloss data was obtained using a BYK Micro Tri-gloss instrument. Additional optical data was obtained using a BYK Mac colorimeter. The results of these measurements are summarized in Table 4 below. Data for Comparative Examples 1 (commercially available Metalure Liquid Black) and 2 (commercially available Metalure L-55700) are shown for comparison.

[0092] Table 4a-c: Optical data from silicon tin alloy effect pigment of Example 3

[0093] [Table 4a]

[0094] [Table 4b]

[0095] [Table 4c]

[0096] From Table 4a, it can be seen that the example has a flop between Comparative Example 1 (Metalure Liquid Black) and Comparative Example 2 (standard PVD aluminum pigment). * value and b * The values ​​are small, indicating an essentially neutral shade. Visually, the effect pigment has a silvery appearance with a strong value flop.

[0097] Example 4a, b: SiGe and SiSn Expansion Tests Silicon germanium and silicon tin alloy flake samples were prepared according to the parameters described in Examples 1-3, but with slightly different compositions. The materials from Example 4 were stripped from their polyester films and homogenized to produce particles with a particle size of 12-15 μm (d 50The pigment dispersion was prepared in propyl glycol methyl ether at 10 wt% non-volatile content (NVM). SEM / EDX analysis was performed on Si 46 Ge 54 and Si 66 Sn 34 The alloy composition of SiGe and SiSn alloys was clarified. a ) were found to be 28 + / - 3 nm and 29 + / - 3 nm, respectively. In this analysis, oxygen content was excluded.

[0098] The binder formulation was prepared by mixing and stirring 43.5 parts of NC E1160 (Hagederon AG, Germany) binder in 30% isopropyl alcohol with 26.5 parts butyl acetate, 26.5 parts xylitol, 0.6 parts butyl diglycol, 1.6 parts butyl glycol in 85% butyl acetate at a binder content of 9% by weight, to which 0.3 parts Byk358N and 1.0 part Byk120 were added as additives.

[0099] Spray inks were formulated with the binder:pigment ratios shown in Table 5. Viscosity was adjusted using a 1:1 solvent mixture of butyl acetate and xylitol. The spray inks were applied to ABS panels using a spray coating machine APL3.3 from Oerter, Germany. Each formulation was sprayed four times to obtain full coverage of each effect pigment.

[0100] Radar penetration measurements were performed using microwave radiation at a frequency of 76.5 GHz using an RMS-D-77 / 79G instrument from Perisens, Germany, as the measurement system. Additional optical data was obtained using a BYK Mac colorimeter.

[0101] The radar attenuation and optical results for the spray panel are shown in Table 5. The radar data was background corrected to account for losses caused by the uncoated substrate.

[0102] Table 5a, b, c: Radar and optical characterization of Example 3 versus comparative examples

[0103] [Table 5a]

[0104] [Table 5b]

[0105] [Table 5c]

[0106] It can be seen that the silicon germanium and silicon tin alloy effect pigments provided essentially zero radar attenuation, while both metallic effect pigments showed significant losses. All applications were achieved with the full hiding power of the effect pigments.

[0107] In comparison across all shades of coverage, the optical flop exhibited by the effect pigment alloy of Example 4 is on the same level as that of the effect pigments of Comparative Examples 1 and 2. * A value of 15 is typically considered a brightness index and is between Comparative Examples 1 and 2.

[0108] Example 5: SiGe and SiSn, and Comparative Example 3: Si Further samples of silicon germanium and silicon tin alloy flakes were produced according to Examples 1-3. Additional comparative Si-only samples were produced with various silicon thicknesses. The Si:Ge, Si:Sn, and Si compositions and average particle thickness (t a ) was confirmed by SEM analysis, which is shown in Table 6. Oxygen content was excluded in this analysis.

[0109] All the deposited material was peeled off from the polyester film and homogenized to a particle size of 12-15 μm (d50 The ink was mixed with Eckart's in-house binder. Complex A 40 μm wet film was prepared, consisting of Hagedorn H7 nitrocellulose binder (obtained from Hagedorn AG, Osnabrück, Germany) in a solvent blend of ethyl acetate and propylene glycol methoxy ether. The formulation was based on a binder-to-metal content weight ratio of 1.85:1 and had a total metal content of 1.5%. Samples were drawn down onto flat polyester film using a wire-wound rod to a wet film thickness of 40 μm.

[0110] Gloss and color data were obtained from the backside of each polyester film using a BYK Micro Tri-gloss meter and a BYK Mac colorimeter, respectively. Opacity data were obtained using an X-rite 341C transmission densitometer by averaging six acquisition points along the coated polyester film. The results of these measurements are summarized in Table 6. Data for Comparative Examples 1 (commercially available Metalure Liquid Black) and 2 (commercially available Metalure L-55700) are shown for comparison.

[0111] Table 6a, b: Optical, thickness and composition data from effect pigments of Example 5 and Comparative Examples

[0112] [Table 6a]

[0113] [Table 6b]

[0114] From Table 6, it can be clearly seen that the Examples exhibit a much more neutral color tone compared to a silicon-only sample (Comparative Example 3) of comparable thickness. Furthermore, SiSn Example 5b is nearly as color neutral as the Comparative Example 2 aluminum sample. The gloss values ​​of the Examples are also superior to both the silicon-only sample and Comparative Example 1. The opacity values ​​of the Examples are also superior to both the silicon-only sample and Comparative Example 1. Therefore, the color neutrality, gloss, and coverage of the silicon-germanium and silicon-tin alloys of the present invention are shown to be superior to the silicon-only sample. This disclosure includes the following aspects of the invention. <Aspect 1> A flaky effect pigment including a single platelet as an optically active layer, wherein the single platelet is made of a semiconductor material having a band gap in the range of 0.1 to 2.5 eV, and: (a) Si (1-x) Ge x , 0 < x < 1.00, or (b) Si (1-y) Sn y , 0 < y < 0.90, or (c) Ge (1-z) Sn z [[ID=四十二]]、0 < z ≦ 0.60、又は (d) Si (1-m-n) Ge m Sn n , 0 < m < 1.00, 0 < n < 1.00, However, x < 1.00; y < 1.00, z < 1.00 and m + n < 1.00, Having an average atomic composition of, Flaky effect pigment. <Aspect 2> The flaky effect pigment according to Aspect 1, wherein the band gap is in the range of 0.2 to 1.4 eV. <Aspect 3> The single platelet semiconductor is: (a) Si (1-x) Ge x , 0.01 < x < 0.9, preferably 0.02 ≦ x ≦ 0.8, or (b) Si (1-y) / Sn y , 0.02 ≦ y ≦ 0.75, or (c) Ge (1-z) Sn z , 0.02 ≦ z ≦ 0.5, or (d) Si (1-m-n) Ge m Sn n , 0.02 ≦ m ≦ 0.8, 0.02 ≦ n < 0.75 Having an average atomic composition of, the flaky effect pigment according to Aspect 1 or 2. <Aspect 4> The single platelet semiconductor is: (a) Si (1-x) Ge x , <0.05 ≦ x ≦ 0.65, or (b) Si (1-y) Sn y , 0.05 ≦ y ≦ 0.55, or (c) Ge (1-z) Sn z , 0.05 ≦ z ≦ 0.4, or (d) Si (1-m-n) Ge m Sn n , 0.05 ≦ m ≦ 0.65, 0.05 ≦ n < 0.55 Having an average atomic composition of, the flaky effect pigment according to any one of Aspects 1 to 3. <Aspect 5> The average thickness t of the single semiconductor platelet a Is in the range of 5 to 160 nm, the flaky effect pigment according to any one of Aspects 1 to 4. <Aspect 6> The effect pigment has an average thickness t of the single semiconductor platelet in the range of 15 to 40 nm a And has a silver appearance, the flaky effect pigment according to any one of Aspects 1 to 5. <Aspect 7> The effect pigment has an average thickness t of the single semiconductor platelet in the range of greater than 40 to 160 nm a And has a colored appearance, the flaky effect pigment according to any one of Aspects 1 to 6. <Aspect 8> The d of the particle size distribution 50 8. The flake effect pigment according to any one of the preceding embodiments, wherein is 2 to 100 μm. <Aspect 9> Aspect ratio d 50 / t a 9. The flake effect pigment according to any one of the preceding embodiments, wherein is in the range of 30 to 2000. <Aspect 10> The single semiconductor platelet is made of a transparent, non-optically active metal oxide having a refractive index of n<1.8, preferably SiO 2 10. The flake effect pigment according to any one of the preceding embodiments, wherein the flake effect pigment is coated or surrounded by a <Aspect 11> 11. The flake effect pigment according to any one of the preceding aspects, wherein the effect pigment is further coated with a surface modifier, such as an organofunctional silane, a titanate, an aluminate or a zirconate, a phosphate ester, a phosphonate ester, a phosphite ester, and combinations thereof. <Aspect 12> 12. A method for producing a flake effect pigment according to any one of aspects 1 to 11, comprising: (a) providing a flexible substrate coated with a release agent; (b) depositing a semiconductor material having a band gap in the range of 0.1 to 2.5 eV onto the flexible substrate (a) under ultra-high vacuum conditions; (c) peeling the semiconductor film from the flexible substrate in a suitable solvent and milling in a dispersion to obtain semiconductor flakes; (d) separating the semiconductor flakes from the solvent; and (e) optionally, performing further steps, such as further size classification of the semiconductor flakes or dispersing the semiconductor flakes in different solvents, and further surface treatment steps; A method comprising the steps of: <Aspect 13> 13. A method for producing a flake effect pigment according to embodiment 12, wherein step (b) is carried out by a roll-to-roll process. <Aspect 14> 14. Method for producing flake effect pigments according to embodiment 12 or 13, wherein step (b) is carried out by an electron beam process. <Aspect 15> A coating system comprising a binder and the flake effect pigment according to any one of embodiments 1 to 11.

Claims

1. 1. A flake effect pigment comprising single platelets as the only optically active layer, the single platelets consisting of a semiconductor material having a band gap in the range of 0.1 to 2.5 eV, the average thickness t ａ is in the range of 5 to 160 nm, and: (a) Si （１－ｘ） Ge ｘ , 0<x<1.00, or (b)Si （１－ｙ） Sn ｙ 、0<y<0.90 However, x<1.00; y<1.00, having an average atomic composition of Flake effect pigment.

2. 2. The flake effect pigment of claim 1, wherein the band gap is in the range of 0.2 to 1.4 eV.

3. The single platelet semiconductor comprises: (a) Si （１－ｘ） Ge ｘ , 0.01<x<0.9, preferably 0.02≦x≦0.8, or (b)Si （１－ｙ） Sn ｙ 、0.02≦y≦0.75、 3. The flake effect pigment according to claim 1, having an average atomic composition of

4. The single platelet semiconductor comprises: (a) Si （１－ｘ） Ge ｘ , 0.05≦x≦0.65, or (b)Si （１－ｙ） Sn ｙ 、0.05≦y≦0.55、 3. The flake effect pigment according to claim 1, having an average atomic composition of

5. The effect pigment has an average thickness t of the single semiconductor platelets in the range of 15 to 40 nm. ａ 3. The flake effect pigment according to claim 1, having a silvery appearance.

6. The effect pigment has an average thickness t of the single semiconductor platelets in the range of from more than 40 to 160 nm. ａ 3. The flake effect pigment according to claim 1, wherein the pigment has a colored appearance.

7. Particle size distribution d ５０ 3. The flake effect pigment according to claim 1, wherein the particle size is from 2 to 100 μm.

8. Aspect ratio d ５０ / t ａ 3. The flake effect pigment according to claim 1, wherein the .times. ...

9. The single semiconductor platelet is made of a transparent, non-optically active metal oxide having a refractive index of n<1.8, preferably SiO ２ 3. The flake effect pigment according to claim 1, wherein the pigment is coated or surrounded by a

10. 3. The flake effect pigment according to claim 1, wherein the effect pigment is further coated with a surface modifier, such as an organofunctional silane, a titanate, an aluminate or a zirconate, a phosphate ester, a phosphonate ester, a phosphite ester, and combinations thereof.

11. 3. A method for producing the flake effect pigments according to claim 1 or 2, comprising the steps of: (a) providing a flexible substrate coated with a release agent; (b) depositing a semiconductor material having a band gap in the range of 0.1 to 2.5 eV onto said flexible substrate (a) under ultra-high vacuum conditions; (c) peeling the semiconductor material from the flexible substrate in a suitable solvent and milling in a dispersion to obtain semiconductor flakes; (d) separating the semiconductor flakes from the solvent; and (e) optionally, performing further steps, such as further size classification of the semiconductor flakes or dispersing the semiconductor flakes in different solvents, and further surface treatment steps; A method comprising the steps of:

12. 12. The method for producing flake effect pigments according to claim 11, wherein step (b) is carried out by a roll-to-roll process.

13. 12. The method for producing flake effect pigments according to claim 11, wherein step (b) is carried out by an electron beam process.

14. 3. A coating formulation comprising a binder and the flake effect pigments according to claim 1 or 2.

Images