PRODUCTION OF PIGMENTS WITH DEFINED SIZE AND SHAPE

Description

[0001] The invention relates to a process for producing pigments of defined size and shape, as well as pigments produced thereby.

[0002] Manufacturing processes for producing pigments or particles are known from EP 2 021 401 A2, WO 2007 / 105001 A2, US 9 095 899 B2, and US 9850385 B2. In these processes, predetermined breaking points in a layer from which the pigments or particles are produced are created by providing separate cells enclosed by so-called walls or frames in a matrix to which the layer is applied. EP 2 039 729 A2 and EP 2 062 947 A1 describe similar manufacturing processes in which embossed or etched frames are produced. These manufacturing processes create predetermined breaking points in the layer from which the pigments or particles are produced, which correlate with the frames / walls of the matrix. From WO 2019 / 057322 A1, a process for producing pigments is known, according to which a layer structured with cracks is used, on which a pigment layer is applied and removed to produce pigments.In addition, US 2010 / 0175587 A1 concerns the production of interference pigments based on multi-coated platelet-shaped substrates and their use in, among other things, paints, coatings, printing inks, plastics and cosmetic preparations.

[0003] These manufacturing processes result in a high proportion of the surface area of ​​the matrix being occupied by the walls or frames. This significantly reduces the pigment yield, especially when producing small pigments. Furthermore, this can result in a large number of small fragments that impair the optical appearance of the pigments. Furthermore, parts of the layer from which the pigments are produced, which have been applied to the walls / frames of the matrix, can remain undesirably on the actual pigments. This can lead to undesirable optical effects, particularly on sloped surfaces of the walls / frames.

[0004] The aim is therefore to provide a process for the production of pigments of high quality and high yield.

[0005] The invention is defined in independent claims 1, 14, and 15. The dependent claims relate to preferred developments.

[0006] One embodiment relates to a process for producing pigments of defined size and shape as defined in claim 1.

[0007] The process creates partially delimited surface areas of the surface structure. In other words, adjacent surface areas are only partially separated from each other by the three-dimensional structural elements. Furthermore, the partial delimitation of each surface area is achieved by a plurality of three-dimensional structural elements. In other words, the delimiting three-dimensional structural elements of each surface area are fragmented. Thus, the surface areas are not separated from each other by continuous walls or frames. This minimizes the surface coverage with the three-dimensional structural elements and optimizes the pigment yield.

[0008] Furthermore, the three-dimensional structural elements lead to breakage along the connecting line between the nearest neighbors of the three-dimensional structural elements during detachment of the pigment material layer or during a subsequent process step. The three-dimensional structural elements and their connecting lines between nearest neighbors thus define predetermined breaking points and break lines during detachment of the pigment layer and creation of the pigments in step c). The predetermined breaking points do not completely coincide with the three-dimensional structural elements, but also include the break lines. The break lines predominantly lead to clean break edges that run at an angle, in some examples perpendicular, to the surface of the pigment, while reducing artifacts at the break edges. This prevents the loss of active and valuable pigment material at the break line between the three-dimensional structural elements.At the same time, a high quality of the pigments produced is maintained.

[0009] The process thus enables both a reduction in material loss and optimal pigment quality and surface yield in the production of pigments with a defined shape and size. The latter means that the surface area occupied by the three-dimensional structural elements is minimized and the pigment yield is optimized. The lower the material loss and the higher the pigment yield, the more economically the pigments can be produced.

[0010] The low surface coverage of the three-dimensional structural elements also reduces the amount of small fragments that arise when the pigment layer is removed. Furthermore, the amount of pigment layer particles that were applied to the walls / frames of the surface structure and remain attached to the pigments upon removal is minimized. This optimizes the quality of the resulting pigments. Furthermore, a well-defined, narrow size distribution of the pigments can be achieved, eliminating the need to grind the pigments after the pigment material layer has been removed from the surface structure.

[0011] In the process, the surface areas can each be defined by 1% to 99%, preferably 10% to 90%, more preferably 30% to 70%, of the three-dimensional structural elements. This allows the length of the fracture lines between the nearest neighbors of the three-dimensional structural elements to be varied, providing the aforementioned positive effects of the surface structure formed in the process. Furthermore, the extent of fragmentation of the three-dimensional structural elements, i.e., the extent of the interruptions between the three-dimensional structural elements, can be varied, e.g., depending on the pigment material.

[0012] In the process, the surface structure and / or surface areas can be covered by the three-dimensional structural elements to a degree of 0.1 to 10%, preferably less than 7%. Such a degree of coverage of the three-dimensional structural elements helps ensure that the three-dimensional structural elements do not impair the optical appearance of the produced pigments.

[0013] In the process, the three-dimensional structural elements can be arranged separately from one another. This allows, as explained above, the formation of fracture lines between the nearest neighbors of the three-dimensional structural elements. Furthermore, the three-dimensional structural elements can be arranged at corners and / or sides of the surface areas in a top view of the surface structure. The aforementioned measures promote minimization of surface coverage with the three-dimensional structural elements and optimal pigment yield.

[0014] In the method, each boundary between adjacent surface regions can be provided with at least two of the three-dimensional structural elements arranged along the boundary. This results in the above-described fracture line being provided at each boundary between adjacent surface regions. Furthermore, at least a portion of adjacent surface regions can be formed with a partially continuous surface. This applies in particular to surface regions formed at the same height level relative to a base level of the surface structure. A partially continuous surface of adjacent surface regions simplifies the manufacturing process.

[0015] In the process, at least some of the three-dimensional structural elements, viewed from above onto the surface structure, can be formed as a regular pattern partially delimiting the surface regions. Furthermore, at least some of the three-dimensional structural elements, viewed from above onto the surface structure, can be formed as a pattern selected from a polygon pattern, a pattern of complementary shapes, and a freeform pattern. With a finely structured pattern of the three-dimensional structural elements, correspondingly complex shapes of the pigments, such as Escher motifs, can also be realized.

[0016] In the process, at least some of the surface regions can be formed parallel to a base level, in particular to a plane of the base level, of the surface structure. Furthermore, at least some of the surface regions can be formed with a slope that runs obliquely to a base level of the surface structure. These measures allow the surface structure to be provided with plane-parallel and / or inclined surfaces, which, depending on the method used to produce the surface structure in step a), can have a positive effect on the quality of the pigments.

[0017] In the process, at least some of the surface regions can be formed at the same height. This promotes the formation of the fracture edges explained above. At least some of the surface regions can be formed at different heights. This can simplify the formation of the fracture edges. Furthermore, in the process, at least some of adjacent surface regions can be formed at different heights. This promotes differentiation between adjacent pigments in step c) during detachment of the pigment layer.

[0018] In the process, at least some of the three-dimensional structural elements can be formed as elevations arranged between the surface regions. Alternatively or additionally, at least some of the three-dimensional structural elements can be formed as depressions arranged between the surface regions. The surface structure, together with the three-dimensional structural elements, can be designed with binary, e.g. plane-parallel, or non-binary, e.g. V-shaped, cross-sectional profiles. The binary profiles represent a very good predetermined breaking point. With non-binary profiles, the pigment layer can be applied relatively thinly but continuously in the wall region. The degree of fragmentation of the three-dimensional structural elements can vary. For example, the surface regions can be separated from one another to a high extent by the three-dimensional structural elements.In other examples, the surface areas may be separated from each other to a small extent by the three-dimensional structural elements and may additionally be separated from each other, for example, in height.

[0019] Furthermore, at least some of the three-dimensional structural elements can be formed as venting structures, e.g., venting slots, arranged between the surface regions. The latter can be provided as the three-dimensional structural elements, in particular, between adjacent surface regions formed at different height levels. As a result, when an embossing process is used in step a), air pockets can escape along the venting structures at the higher height levels, particularly at the highest height level, of the surface structure.

[0020] In the method, at least some of the three-dimensional structural elements can be formed with a width of 0.2 µm to 4 µm, preferably 0.5 µm to 3 µm, and / or a height of 1 µm to 10 µm, preferably 2 µm to 6 µm. In particular, the three-dimensional structural elements can be formed as walls or trenches with a corresponding aspect ratio (height to width). For example, color shift (CS) pigments with a double CS coating and a typical total layer thickness of approximately 1 µm can be formed with a width of the three-dimensional structures that is not less than approximately 2 µm. The dimensions of the surface regions can be 5 µm to 50 µm, preferably 15 µm to 35 µm. Furthermore, at least some of the three-dimensional structural elements can be formed with the same or different dimensions, in particular with the same or different height and / or width.With a delicate pattern of three-dimensional structural elements, even complicated shapes of the pigments can be realized, such as Escher motifs.

[0021] In the process, at least some of the surface regions can be formed with the same size and / or shape. This promotes the creation of a well-defined, narrow size distribution of the pigments. The provision of surface regions of the same shape leads to a high yield of essentially uniform pigments.

[0022] The surface regions can also be arranged in parallel, adjacent columns. This allows a regular pattern of surface regions to be created. At the same time, the number of surface regions per unit area of ​​the surface structure is optimized. By implementing measures to create a regular arrangement and / or pattern of surface regions, the yield of essentially uniform pigments can be increased. Furthermore, a well-defined, narrow size distribution of the pigments can be achieved, eliminating the need for grinding the pigments after the pigment material layer has been removed from the surface structure.

[0023] In the process, at least some of the surface regions, viewed from above, can be formed with a contour selected from a polygonal contour, a complementary contour, and a freeform contour. For example, the surface regions each have a surface with a polygonal contour or a contour of an Escher motif. This promotes the diversity of shapes of the pigments that can be produced. The aforementioned measures support the formation of regular, quasi-periodic, or random pigment shapes.

[0024] Furthermore, at least some of the surface areas can be provided with one or more markings, e.g., by embossing. Due to their profile height and / or shape, these markings do not lead to predetermined breaking points in the pigment material layer. For example, markings of the surface areas in the form of Escher motifs can be used as a basis for corresponding marking of the pigments, e.g., on the surfaces of the surface areas. The surface areas can also be provided with markings to create, for example, holograms, nanostructures, and / or micromirrors for optical effects.

[0025] In the method of embodiments, in step a), the production of the three-dimensional surface structure on the substrate can be carried out at least partially by an embossing process. For example, an embossing layer can be applied to the substrate and then embossed. Alternatively, the surface of the substrate can be embossed or the substrate can be cast with the three-dimensional surface structure. The embossing process can be carried out, for example, in a roll-to-roll process. The substrate can be, for example, a carrier film, e.g. made of PET (polyethylene terephthalate), PE (polyethylene), PC (polycarbonate), PVC (polyvinyl chloride), PMMA (polymethyl methacrylate), or a combination thereof. The substrate can alternatively be formed from a rigid material, such as quartz or glass.

[0026] In step a) of the method, the three-dimensional surface structure can be created by a method selected from: a1) an embossing method comprising the steps of: applying a soluble, in particular water-soluble, embossing layer as a release layer to the substrate and performing a lithographic, in particular photolithographic, process, hot embossing, or UV embossing; and / or a2) an embossing method comprising the steps of: providing a substrate deformable by hot embossing or applying an insoluble embossing layer to the substrate, performing hot embossing or UV embossing; and applying a soluble, in particular water-soluble, release layer. The aforementioned methods allow the advantages of the method of embodiments to be realized particularly extensively.In steps a1) and / or a2), markings can also be embossed, for example to produce flat holograms, nanostructures and / or micromirrors on the pigments for optical effects.

[0027] In step a1), lithographic processes involving exposure and development can be used, in which a release resist applied as a release layer is simultaneously used as a photolithographic resist. Furthermore, UV embossing can be performed by irradiating the release layer with UV light, whereby the release layer contains or is formed from a soluble embossing resist curable in the UV frequency range.

[0028] In step a2), the release layer can be applied with a layer thickness of 50 to 7000 nm, preferably 100 to 5000 nm. Furthermore, the release layer can be applied as a layer that is substantially conformal or non-conformal to the three-dimensional surface structure, e.g., with a substantially constant layer thickness. The embossed layer can contain or be formed from an insoluble hot-stamping or UV varnish. When applying step a2), the substrate provided with the embossed layer can be reused.

[0029] In step b) of the method of embodiments, a pigment material layer containing one or more inorganic materials and / or one or more organic materials can be applied to the surface structure. For example, in step b), a pigment material layer can be applied by vapor deposition (physical vapor deposition PVD, chemical vapor deposition CVD) or other coating methods. The pigment material layer can also be applied in a roll-to-roll process. The pigment material layer can be formed as a monolayer or as a multilayer of the same or different materials. The pigment material layer can be a metallization or can contain a metallization.The following materials can be used for the pigment material layer, for example, individually or in any combination in one or more layers: a color-shift effect material (color shift (CS) material, thin-film interference coating), a phase-change material (phase change material); a magnetic material; and one or more identical or different materials selected from a metal, an alloy, a dielectric, an oxide, a sulfide, and a fluoride. For example, a color-shift effect material can be used in the form of or with a phase-change material, or a magnetic color-shift effect material can be used. Furthermore, the pigment material layer can also comprise one or more organic layers, which are applied, for example, by means of PVD, CVD, printing, or spraying.

[0030] In step c) of the process, detachment can be achieved by: mechanical detachment, e.g. using a scraper, applying an embossed or metal transfer, applying a release layer and / or a template layer and dissolving the same. Detachment can be achieved, for example, in a roll-to-roll process. During detachment, the pigment material layer can be broken down into fragments. This allows the pigments to be produced directly in the desired size and shape, and costly grinding of the pigments can be avoided. Alternatively or additionally, the detached pigment material layer or its fragments and / or the pigments themselves can be ground. The grinding parameters are selected so that the pigment material layer breaks along the intended breaking points. The pigments can be surface treated and / or dried.For example, the pigment material layer can be removed from the surface structure by dissolving a release layer applied beneath the pigment material layer during the process with a solvent, particularly water. This can, in particular, be the release layers produced by the aforementioned steps a1) and a2). If a carrier film is used as the substrate and a surface structure with depressions is formed on it as the three-dimensional structural elements, a dry stripping process can also be used in step c) to remove the pigment material layer.

[0031] A further embodiment provides pigments as defined in claim 14, obtained by the process according to any one of the preceding claims.

[0032] Another embodiment relates to a use of pigments of the aforementioned embodiment in a printing ink.

[0033] The invention is explained in more detail below using exemplary embodiments with reference to the accompanying drawings, which also disclose features essential to the invention. These exemplary embodiments are for illustrative purposes only and are not to be interpreted as restrictive. For example, a description of an exemplary embodiment with a large number of elements or components should not be interpreted as meaning that all of these elements or components are necessary for implementation. Rather, other exemplary embodiments may also contain alternative elements and components, fewer elements or components, or additional elements or components. Elements or components of different exemplary embodiments may be combined with one another unless otherwise stated. Modifications and variations described for one of the exemplary embodiments may also be applicable to other exemplary embodiments.To avoid repetition, identical or corresponding elements in different figures are designated by the same reference numerals and are not explained more than once. The figures show: . Fig. 1a to 1c show a layer sequence of steps of a first exemplary embodiment of the method with schematic cross-sectional views; Fig. 2a and 2b show a schematic plan view of a surface structure produced using the method of the first exemplary embodiment; Fig. 3 show a schematic plan view of a surface structure that is also obtainable using the method of the first exemplary embodiment; Fig. 4a to 4d show schematic cross sections of three-dimensional structural elements that can be formed in exemplary embodiments of the method; Fig. 5a show a schematic plan view of a surface structure with hexagonal surface regions; Fig. 5b and 5c show schematic plan views of exemplary surface structures with hexagonal surface regions; Fig. 6a to 6c show schematic plan views of exemplary surface structures with hexagonal surface regions; Fig. 7a to 7c show schematic plan views of exemplary surface structures with hexagonal surface regions, and Fig.8a to 8c show schematic top views of exemplary surface structures with hexagonal surface areas and fragmentations of three-dimensional structural elements.

[0034] In the following, the description of value ranges is that specifying a broad range with narrower alternative or preferred ranges also discloses ranges that can be formed by any combination of specified lower range limits with specified upper range limits. The term "slope running obliquely to a base level of the surface structure" and variations thereof can mean, in the present case, that the slope relative to a plane of the base level is 0.01 to 1, preferably 0.02 to 0.75, particularly preferably 0.05 to 0.5.

[0035] Fig. 1a bis 1c show a layered sequence of steps of a first embodiment of the method with schematic cross-sectional views. In the first embodiment, in step a) of the method, a three-dimensional surface structure is created by an embossing process.

[0036] For this purpose, as in Fig. 1a As shown, a carrier film made of PET (polyethylene terephthalate) is provided as a substrate 11, onto which an embossing layer made of a soluble embossing lacquer 13 is applied, which also functions as a release layer. A water-soluble embossing layer made of, for example, polyynylpyrrolidone (PVP), modified starch, polyacrylic acid, polyethylene glycol, hydroxypropyl cellulose, hydroxyethyl cellulose, casein, gum arabic, carboxymethyl cellulose, polyvinyl alcohol (PVOH), dextrin, or a mixture of two or more of the aforementioned substances is produced as a thermoplastic hot stamping lacquer using a roll-to-roll process on the carrier film. In the present example, PVOH is used. The water-soluble embossing layer can be printed with a layer thickness of 500 nm to 20 µm. The release layer can be applied, for example, by means of gravure printing, flexographic printing, slot die, or spray nozzle.Alternative thermoplastic hot stamping lacquers can be selected from, for example, PMMA, PVA, PS, which are soluble in solvents other than water.

[0037] Then, as in Fig. 1b As shown, in a roll-to-roll process, a surface structure 10 with essentially uniform surface regions 12 at the same height level is produced by hot embossing the embossing lacquer 13. The embossing lacquer can be only partially embossed. Alternatively, a thermoplastically deformable carrier foil can also be hot embossed. The surface regions 12 are each partially delimited by a plurality of grooves 20 as three-dimensional structural elements. The grooves 20 have a rectangular contour in cross-section with essentially vertical side walls with a height of, for example, 2 µm and a base area with a width of, for example, 2 µm. The aspect ratio of the grooves is therefore 1:1. The surface regions 12 form a pattern with square units in plan view, as, for example, in Fig. 2a and are arranged in columns 14 and 15.

[0038] How Fig. 1c shows, in step b) of the method, a pigment material layer 19 consisting of copper is applied to the surface structure 10, i.e., to the embossed layer 13 with the surface regions 12 and the trenches 20, using a roll-to-roll process. In alternative examples, a pigment material layer 19 consisting of a multi-layer interference coating, optionally a double interference coating, can be applied. The pigment material layer 19 is provided on the surface regions 12 and in the trenches 20. The trenches 20 form a binary cross-sectional profile that is plane-parallel to the surface regions 12. The binary profiles represent a very good predetermined breaking point, since the applied pigment layer is interrupted by the height difference. In this way, predetermined breaking points for the production of the pigments are provided in the pigment material layer 19 applied to the surface structure.

[0039] Fig. 2a shows a schematic plan view of the surface structure 10 produced using the method of the first embodiment. The square surface regions 12 are arranged in mutually parallel columns 14 and 15. The trenches 20 have a cross shape at the corners of the surface regions 12 and a longitudinal shape at the sides of the surface regions 12. Thus, the trenches 20 form a pattern delimiting the surface regions. Due to the distances between the trenches 20, the surfaces of adjacent surface regions 12 are connected to one another.

[0040] In step c) of the method (not shown), the pigment material layer 19 consisting of copper is detached from the surface structure 10 by dissolving the PVOH embossing varnish of the release layer with water. If the embossing varnish of the release layer consists of a water-insoluble thermoplastic, other solvents are used. The trenches 20 define the predetermined breaking points, and the connecting lines between the nearest trenches 20 define fracture lines during the detachment of the pigment layer 19 and the production of the pigments in step c). In the present example, the fracture lines between the trenches 20 are approximately 15 µm long, with a diameter of the produced pigments of approximately 25 µm. During the detachment of the pigment material layer 19, a plurality of copper pigments with essentially the same square shape and a narrow size distribution are produced by breaking at the trenches 20 and at the fracture lines between the trenches 20 of the pigment material layer 19.When using a multilayer interference coating as the pigment material layer 19, interference pigments are produced.

[0041] When the pigment material layer 19 is removed, the predetermined breaking points do not completely coincide with the grooves 20, but also include the fracture lines between them. The fracture lines predominantly result in clean fracture edges, which in the present example run perpendicular to the surface of the pigment. This prevents the loss of active and valuable pigment material at the fracture line between the three-dimensional structural elements. At the same time, a high yield and high quality of the produced pigments are maintained.

[0042] Fig. 2b shows schematically a surface structure 30 with a size of 20 µm x 20 µm, which is also obtainable using the method of the first exemplary embodiment. The surface regions 12 form a pattern with square units in plan view and are arranged in columns 14, 15. Trenches 32 are formed only at the corners of the surface regions 12 and have a cross shape. In this way, the trenches 32 form a pattern delimiting the surface regions 12. The trenches 32 have essentially vertical side walls with a height of, for example, 2 µm and a base area with a width of, for example, 2 µm. The trenches 32 define the predetermined breaking points and the connecting lines between the nearest trenches 32 define the breaking lines 33 when the pigment layer 19 is detached and the pigments are produced in step c). The breaking lines 33 between the trenches are 15 µm long in the present example.When the pigment material layer 19 is detached, a plurality of copper pigments with essentially the same square shape and with a narrow size distribution are produced by breaking at the trenches 32 and at the fracture lines 33 between the trenches 32 of the pigment material layer 19.

[0043] Fig. 3 shows a schematic view of a surface structure 40 which is also obtainable using the method of the first exemplary embodiment. In plan view, the surface regions 120 form a pattern with hexagonal units and are arranged in columns 140, 150. Walls 300 are formed as three-dimensional structural elements delimiting the surface regions 120. The walls 300 are formed only at the corners of the surface regions 120. The walls 300 have, for example, essentially vertical side walls with a height of, for example, 2.5 µm and a width of, for example, 2 µm. The walls 300 define the predetermined breaking points, and the connecting lines between the nearest walls 300 define the breaking lines when the pigment layer 19 is detached and the pigments are produced in step c).

[0044] Fig. 4a bis 4d schematically illustrate variants of cross-sections of three-dimensional structural elements that can be formed in embodiments of the method. Fig. 4a shows the surface structure 10 covered with the pigment material layer 19, which is produced with the first embodiment of the method and in Fig. 1c Alternatively, in the embossing step a) of the method, walls 22 can be formed as three-dimensional structural elements in the embossing layer 13 instead of trenches, such as Fig. 4b The formation of the walls 22 also leads to a binary cross-sectional profile of the surface structure, wherein the walls 22 are formed plane-parallel with the surface areas 12. This binary profile also represents a very good predetermined breaking point, since the applied pigment layer 19 is interrupted by the height difference. Instead of the trenches 20 with a rectangular cross-sectional contour and essentially vertical side walls, trenches 24 with a width of, for example, 2 µm with inclined side walls with a height of, for example, 2 µm can be produced, as in Fig. 4c Alternatively, walls 26 with a width of e.g. 2.5 µm and inclined side walls with a height of e.g. 3 µm can be formed as three-dimensional structural elements, such as Fig. 4d illustrated.

[0045] A second embodiment of the method also comprises three steps. In step a), a three-dimensional surface structure is created by an embossing process. For this purpose, a carrier film made of PET (polyethylene terephthalate) is provided as the substrate. An insoluble embossing layer 13 made of water-insoluble hot stamping lacquer PMMA (polymethyl methacrylate) is applied to the surface of the carrier film in a roll-to-roll process. Alternative water-insoluble thermoplastic hot stamping lacquers are PVA (polyvinyl acetate) or PS (polystyrene). In the embossing layer 13, a surface structure 10 with uniform surface regions 12 is created by hot stamping in a roll-to-roll process, analogous to the first example, each of which has a square, flat surface 16 and is arranged in columns 14 and 15.

[0046] A release layer (not shown) made of water-soluble PVOH is printed in a roll-to-roll process onto the surface structure 10 produced in step a) of the second exemplary embodiment. The layer thickness of the release layer is selected in relation to the height difference of the surface regions 12 such that it covers these and replicates the elevations and depressions of the surface structure 10. This means that the release layer is formed as a layer conforming to the surface structure 10. The release layer can preferably be applied with a layer thickness of 50 nm to 2 µm. The release layer can be applied, for example, by gravure printing, flexographic printing, slot die, or spray nozzle. In the present example, a 500 nm PVOH layer is printed by gravure printing.

[0047] In step b) of the process, a pigment material layer made of aluminum (not shown) is applied to the release layer using a PVD process. Predetermined breaking points and break lines for the subsequent production of the pigments are provided in the pigment material layer applied to the release layer, as explained above for the first embodiment.

[0048] In step c) of the process, the aluminum pigment material layer is detached from the surface structure 10 by dissolving the release layer with water. In this process, a plurality of aluminum pigments with essentially the same hexagonal contour and a narrow size distribution are produced by breaking the pigment material layer at the predetermined breaking points.

[0049] The Fig. 5a bis 5c schematically illustrate surface structures with hexagonal surface areas in plan view. The exemplary surface structures of the Fig. 5b und 5c can be produced using the first or second embodiment of the method. In step a), the surface areas are formed at three different height levels. Fig. 5a bis 5c The surface areas of different heights are shown with different brightness levels. The surface areas 502 (low brightness) are located at the highest height level, the surface areas 500 (high brightness) are located at the lowest height level, and the surface areas 501 (medium brightness) are located at a height level between the height levels of the surface areas 500 and 502. The height variation is, for example, 2 to 5 µm. The surface areas 500 and 501 of the example of the Fig. 5b are each bordered on three of six sides of the hexagonal contour by trenches 504 (shown in black) as three-dimensional structural elements. The trenches 504 are as deep as the height difference between the surface areas 500 and 502 as a whole and are fragmented (not in Fig. 5b shown). The fragmentation is analogous to that in Fig. 8a bis 8c illustrated. In the surface areas 501 to 503 of the example of the Fig. 5c Only the adjacent surface areas 500 and 501 on one side of the hexagonal contour are provided with grooves as three-dimensional structural elements, i.e. partially separated. The grooves of the surface structure of the Fig. 5c exhibit fragmentation (not in Fig. 5c shown) analogous to Fig. 8a bis 8c The trenches of the surface structures of the Fig. 5b und 5c are as deep as the overall height difference between surface areas 500 and 502. The trenches 504 serve as vent slots during embossing, allowing air pockets along the trenches to escape during embossing at the highest level.

[0050] The Fig. 6a bis 6c schematically illustrate, in plan view, exemplary surface structures with hexagonal surface regions 600, which are produced with the first or second embodiment of the method. The surface regions 600 are formed in step a) at a height level and are delimited by trenches 601 as three-dimensional structural elements that are fragmented (not in Fig. 6 a bis 6c shown). The fragmentation is analogous to that in Fig. 8a bis 8c illustrated. The width of the trenches 601 decreases from Fig. 6a bis Fig. 6b to.

[0051] The Fig.7a bis 7c and Fig. 8a bis 8c 10 schematically illustrate, in plan view, exemplary surface structures with hexagonal surface regions 700. These can be produced using the first or second embodiment of the method. In step a), the surface regions 700 are formed at a height level and are delimited by walls 701 as three-dimensional structural elements that are fragmented. The fragmentation is not Fig. 7a bis 7c shown, but in Fig. 8a bis 8c The width of the walls 701 decreases from Fig. 7a bis Fig. 7b or from Fig. 8a bis fig. 8c to.

[0052] All embodiments and examples allow for a reduction in the area of ​​the surface structure occupied by the three-dimensional structural elements that define the surface areas. This results in a higher yield with a narrower size distribution of the pigments while avoiding artifacts at the fracture edges of the pigments. Bezugszeichenliste

[0053] 10Surface structure 11Substrate 12Surface area 13Embossing layer 14Gap 15Gap 19Pigment material layer 20Trench 22Wall 24Trench 26Wall 30Surface structure 32Trench 33Fracture line 40Surface structure 120Surface area 140Gap 150Gap 300Wall 500Surface area 501Surface area 502Surface area 504Trench 600Surface area 601Trench 700Surface area 701Wall

Claims

1. A method for producing pigments of defined size and shape, comprising the steps of: a) producing a three-dimensional surface structure (10; 30; 40) on a substrate (11), surface regions (12; 120; 500, 501, 502; 600; 700) being formed which are arranged in columns (14, 15; 140, 150) and are each bordered by a defined by a plurality of three-dimensional structural elements (20; 22; 24; 26; 32; 300; 504; 601; 701); b) applying a pigment material layer (19) to the surface structure (10; 30; 40); c) detaching the pigment material layer (19) from the surface structure (10; 30; 40) and producing pigments, characterized in that in step a) adjacent surface regions are only partially separated from each other by the three-dimensional structural elements and otherwise remain connected to each other.

2. The method according to claim 1, wherein the surface regions are bordered in each case by 1% to 99%, preferably 10% to 90%, more preferably 30% to 70%, of the three-dimensional structural elements (20; 22; 24; 26; 32; 300; 504; 601; 701); and / or wherein the surface structure (10; 30; 40) and / or the surface areas are occupied by the three-dimensional structural elements (20; 22; 24; 26; 32; 300; 504; 601; 701) from 0.1 to 10%, preferably less than 7%.

3. The method according to one of the preceding claims, wherein the three-dimensional structural elements (20; 22; 24; 26; 32; 300; 504; 601; 701) are arranged separately from one another; and / or wherein the three-dimensional structural elements (20; 22; 24; 26; 32; 300; 504; 601; 701) are arranged at corners and / or sides of the surface regions (12; 120; 500, 5 01, 502; 600; 700).

4. The method according to any of the preceding claims, wherein each border between adjacent surface regions (12; 120; 500, 501, 502; 600; 700) is provided with at least two of the three-dimensional structural elements (20; 22; 24; 26; 32; 300; 504; 601; 701) arranged along the border; and / or wherein at least a portion of adjacent surface regions are formed with a partially continuous surface.

5. The method according to any preceding claim, wherein, as seen in a plan view of the surface structure (10; 30; 40), at least some of the three-dimensional structural elements (20; 22; 24; 26; 32; 300; 504; 601; 701) are configured as a regular pattern, which partially borders the surface regions (12; 120; 500, 501, 502; 600; 700); and / or wherein at least some of the three-dimensional structural elements (20; 22; 24; 26; 32; 300; 504; 601; 701) are formed as a pattern selected from a polygon pattern, a pattern of mutually complementary shapes and a free-form pattern.

6. The method according to any of the preceding claims, wherein at least a part of the surface regions (12; 120; 500, 501, 502; 600; 700) is formed parallel to a base level of the surface structure; and / or wherein at least a part of the surface regions is formed with a slope oblique to a base level of the surface structure.

7. The method according to one of the preceding claims, wherein at least some of the surface regions are formed at the same height level; and / or wherein at least some of the surface regions are formed at different height levels; and / or wherein at least some neighboring surface regions are formed at different height levels.

8. The method according to any one of the preceding claims, wherein at least some of the three-dimensional structural elements are formed as elevations arranged between the surface regions; and / or wherein at least some of the three-dimensional structural elements are formed as depressions arranged between the surface regions; and / or wherein at least some of the three-dimensional structural elements are formed as venting structures arranged between the surface regions.

9. The method according to any one of the preceding claims, wherein at least some of the three-dimensional structural elements (20; 2; 24; 26; 32; 300; 504; 601; 701) are formed with a width from 0.2 µm to 4 µm, preferably 0.5 µm to 3 µm, and / or a height from 1 µm to 10 µm, preferably 2 µm to 6 µm, and / or wherein at least some of the three-dimensional structural elements (20; 22; 24; 26; 32; 300; 504; 601; 701) are formed with the same or different dimensions.

10. The method according to one of the preceding claims, wherein at least some of the surface regions (12; 120; 500, 501, 502; 600; 700) are formed with the same size and / or the same shape.

11. The method according to one of the preceding claims, wherein at least some of the surface regions (12; 120; 500, 501, 502; 600; 700), as seen in a plan view of the surface structure (10; 30; 40), are formed with a contour selected from a polygon contour, a contour complementary to one another and a free-form contour; and / or wherein at least some of the surface regions are provided with one or more markings.

12. The method according to one of the preceding claims, wherein in step a) the three-dimensional surface structure (10; 30; 40) is produced at least partially by an embossing process; and / or wherein in step a) the three-dimensional surface structure (10; 30; 40) is produced by a process selected from: a1) an embossing process comprising the steps of: applying a soluble embossing layer (13) as a release layer to the substrate and carrying out a lithographic, in particular photolithographic, process, a hot embossing or an UV embossing; and a2) an embossing process comprising the steps of: providing a substrate that is deformable by hot embossing or applying an insoluble embossing layer (130) to the substrate, carrying out hot embossing or UV embossing; and applying a soluble, in particular water-soluble, release layer.

13. The method according to any of the preceding claims, wherein in step b) a pigment material layer (19) comprising one or more inorganic materials and / or one or more organic materials is applied to the surface structure (10; 30; 40).

14. Pigments obtained by the method according to one of the preceding claims.

15. Use of the pigments according to claim 14 in a printing ink.