Surface coating and composition for producing the surface coating

Abstract

Surface coating, wherein the surface coating comprises a sublimable matting component and has elevations detectable by an optical scanner.

Description

The invention relates to a surface coating and to a composition for producing the surface coating.Methods for optically measuring surfaces, such as, for example, using 3D white light scanners or 3D laser scanners, are known per se. The quality of the measurement depends in particular on the reflection properties of the surface to be measured. Diffuse reflection is particularly favourable for the measurement, so that surfaces which appear matt are better to measure than glossy or even transparent surfaces. It is known that surfaces for improving the reflection properties are therefore provided with a surface coating before the optical measurement, which surface coating ensures a corresponding opacity and diffuse reflection of the surface. Surface coatings have proven particularly successful for this purpose, which are only temporary and separate themselves after a certain time. In this way, a non-destructive measurement can be ensured. Such means for reversibly coating surfaces are known per se.Largely independently of this, it is a challenge in the optical measurement of surfaces to detect objects which have larger planar regions, regions with only slight curvature, and / or only a few edges and / or corners. In the case of three-dimensional optical detection of objects, 3D scanners and the associated software have, in addition to the actual depth measurement, in which the scanner measures the distance from the surface to the scanner in the form of individual points in a field of view (scan field), the task also of placing the detected points in the digital model of the object spatially correctly in relation to the already detected points. Since the surface to be detected is usually larger than the scan field, the correct placement of the newly detected points must be organized by the scan software. In order to ensure this, optical adhesives (scan markers), for example, are used in a known manner, on which the software can be oriented.A disadvantage of this procedure is that the application of scan markers can be correspondingly complicated and also, if appropriate, cannot take place without residue.Alternatively, the software can attempt to automatically superimpose the point clouds found in their overlap. A correct alignment of a plurality of scan views is however only possible if it has enough unique curvature changes which can also be detected in the point cloud. The software searches for similar shape sections in the scan views and tries to superimpose the recorded measurement points in the similar regions (overlap of two scan fields) as well as possible. This process is also called feature-based tracking.An advantage of feature-based tracking is that the more complex application of adhesives can be dispensed with. However, a disadvantage is that surfaces with a small curvature and / or which have only a few edges and / or corners often cannot be measured at all.In the field of methods for optically surveying surfaces, there is therefore still potential for improvement. In particular, there may be potential for improvement in the measurement of surfaces with only slight curvature, and / or few edges and / or corners.It is therefore the object of the present invention to provide improved means for optically measuring surfaces, with which means in particular the aforementioned disadvantages are overcome.This object is achieved by the surface coating according to claim 1, the composition according to claim 10 and the device according to claim 22.The invention proposes a surface coating, wherein the surface coating comprises a sublimable matting component and has elevations detectable by an optical scanner.The surface coating according to the invention can achieve that objects provided with the corresponding surface coating can be detected particularly well by a 3D scanner. The surface coating can ensure, on the one hand, a degree of necessary opacity and diffuse reflection of the surface. On the other hand, the sublimable matting component can remove the surface coating independently after a certain time, so that no complicated cleaning of the object to be measured is obtained. In addition, the fact that the surface coating has elevations detectable by the optical scanner can surprisingly be achieved that the measurement of surfaces with only a small curvature, and / or a few edges and / or corners can also be carried out with feature-based tracking, so that the use of tracking markers can be dispensed with. In particular, it can be achieved in this case that the model obtained represents the scanned-in surface in particular with a low level of distortion. In other words, the surface coating has a topography on which the corresponding elevations are included.In the context of the present invention, the term "elevation" is understood to mean in particular a part of the surface of the surface coating which projects beyond the surface of the surface coating in a region surrounding the elevation. An elevation is defined in particular by its height difference in comparison to the aforementioned environment. In this case, the height difference can be determined in particular on the basis of the maximum height of the elevation in comparison with the average or minimum height of the region surrounding the elevation. As surrounding region, for example, a circle around the highest point of the elevation can be selected. However, it is also possible to define or determine an area of the elevation and to compare the average height of this area with the height of the region surrounding the elevation.The term "sublimable" is to be understood in the sense of the present invention as meaning that the substance concerned can be transferred directly from the solid state of aggregation into the gaseous state of aggregation accordingly. It should be noted here that a sublimable substance in the sense of the present invention does not necessarily have to have a sublimation point or a corresponding pressure or a corresponding temperature has to be set for sublimation. Sublimable substances are therefore also to be understood in particular within the meaning of the present invention as having such a high vapor pressure that they transition over time from the solid to the gaseous state, even at room temperature, for example.Preferably, a sublimable matting component may comprise a matting component having a vapor pressure at 20° C. of ≥2 Pa, preferably ≥5 Pa, more preferably ≥6 Pa, more preferably ≥7 Pa, more preferably ≥8 Pa, particularly preferably ≥9 Pa.For the purposes of the present invention, temperature data are given, unless otherwise stated, for example to boiling points and the like for a pressure of 1 atm.In the following, particular configurations of the protrusions will be described. It has surprisingly been shown that such elevations can each be detected particularly well by the optical scanner, so that particularly good, accurate and low-error feature-based tracking can be carried out.It can preferably be provided that the elevations ≥50 μm protrude beyond a surface of the surface coating in a region surrounding the elevation, preferably ≥60 μm to ≤500 μm, more preferably ≥70 μm to ≤400 μm, more preferably ≥80 μm to ≤300 μm, more preferably ≥90 μm to ≤250 μm, particularly preferably ≥100 μm to ≤200 μm.It can preferably be provided that the elevations are ≥50 μm thick than the surface coating in a region surrounding the elevation, preferably ≥60 μm to ≤500 μm, more preferably ≥70 μm to ≤400 μm, more preferably ≥80 μm to ≤300 μm, more preferably ≥90 μm to ≤250 μm, particularly preferably ≥100 μm to ≤200 μm.It can preferably be provided that the elevations have an average diameter in a range from ≥5 μm to ≤300 μm, more preferably ≥10 μm to ≤250 μm, more preferably ≥20 μm to ≤200 μm, more preferably ≥30 μm to ≤ 175 μm, more preferably ≥40 μm to ≤150 μm, particularly preferably ≥50 μm to ≤125 μm.It can preferably be provided that the surface coating has ≥0.1 elevations / mm2to ≤100 elevations / mm2, preferably ≥1 elevation / mm2to ≤100 elevations / mm2, more preferably ≥2 elevations / mm2to ≤80 elevations / mm2, more preferably ≥3 elevations / mm2to ≤70 elevations / mm2, more preferably ≥4 elevations / mm2to ≤60 elevations / mm2, particularly preferably ≥5 elevations / mm2to ≤100 elevations / mm2, based on the surface of the surface coating.It can preferably be provided that the surface coating has a layer thickness in a range from ≥0.5 μm to ≤30 μm, preferably from ≥1 μm to ≤25 μm, more preferably from ≥2 μm to ≤20 μm, and particularly preferably from ≥3 μm to ≤30 μm.This can ensure that the surface coating does not overlap the scanned surface to such an extent that the measurement result is significantly falsified, on the one hand, and that sufficient coverage of the surface is achieved, on the other hand, in order to achieve the most uniform possible reflection properties.It may preferably be provided that the surface coating consists of the sublimable matting component.This can ensure that the surface coating is removed automatically again essentially without residue after application.It can preferably be provided that the sublimable matting component is a cyclic hydrocarbon which is solid at 20° C.It can preferably be provided that the sublimable matting component is selected from the group consisting of cyclododecane, adamantane and mixtures thereof, wherein the sublimable matting component is preferably cyclododecane.It has surprisingly been possible to show that with such matting components the above-described surfaces with elevations can be produced particularly well and at the same time particularly good matting properties can be achieved. Although it is not possible to achieve surfaces with the claimed elevations with known means for producing reversible surface coatings based on such matting components, it has surprisingly been shown that it is possible to provide other compositions based on the same matting components from which a corresponding surface coating can be produced in accordance with the present invention.The invention thus further proposes a composition for producing the surface coating of the invention, comprising a sublimable matting component and a solvent, wherein the solvent comprises a first solvent and a second solvent, wherein the first solvent is a hydrocarbon having a boiling point of ≥25 °C, a mixture of hydrocarbons having a lowest boiling point of ≥25 °C, or a ketone having a boiling point of ≥70 °C, and the second solvent is a ketone having a boiling point of ≥40 °C.It has surprisingly been shown that the surfaces according to the invention can be produced with such compositions. Without being bound to a theory, it is assumed that the combination of the first and second solvents influences the solubility of the matting component in such a way that it can be applied on the one hand in a sufficient amount to obtain a sufficiently thick surface coating. On the other hand, it is considered that the composition of the solvent mixture continuously changes after application of the composition to the surface by beginning evaporation. This has an influence in particular on the solubility of the matting component and its crystallization behavior. Without being bound by theory, it is assumed that the solvent initially evaporates rapidly and the matting component initially crystallizes rapidly and uniformly thin. As soon as the solvent has already substantially completely evaporated and the ratio of the first to the second solvent has changed accordingly, the remaining solvent evaporates more slowly and larger crystals are formed in places, which overall form the desired elevations.Particular configurations of the matting component and of the solvent are described below. It has surprisingly been shown that such compositions can each produce the desired elevations particularly well, so that particularly good, accurate and low-error feature-based tracking can be carried out.It can preferably be provided that the sublimable matting component is a cyclic hydrocarbon which is solid at 20° C.It can preferably be provided that the sublimable matting component is selected from the group consisting of cyclododecane, adamantane and mixtures thereof, wherein the sublimable matting component is preferably cyclododecane.It can preferably be provided that the first solvent is different from the second solvent.It can preferably be provided that the first solvent is selected from the group consisting of n-pentane, isopentane, cyclopentane, hexane, cyclohexane, heptane, cycloheptane, octane, petroleum ether 30-40, petroleum ether 40-60, petroleum ether 40-65, petroleum ether 40-80, petroleum ether 40-100, butanone (methyl ethyl ketone) or mixtures thereof, wherein the first solvent is preferably selected from n-pentane, cyclopentane, butanone (methyl ethyl ketone) and mixtures thereof, particularly preferably wherein the second solvent is n-pentane.It can preferably be provided that the second solvent is selected from the group consisting of acetone, butanone (methyl ethyl ketone), cyclohexanone, methyl isobutyl ketone, and mixtures thereof, wherein the second solvent is preferably selected from acetone, butanone and mixtures thereof, particularly preferably wherein the second solvent is acetone.It can preferably be provided that the first solvent is selected from n-pentane and the second solvent is selected from acetone.It can preferably be provided that the solvent comprises the first solvent and the second solvent in a weight ratio of the first solvent to the second solvent in a range from ≥1:10 to ≤2:1, preferably ≥1:9 to ≤1:1, more preferably ≥1:8 to ≤1:2, more preferably ≥1:7 to ≤1:3, more preferably ≥1:6 to ≤1:4, and particularly preferably from ≥1:5 to ≤1:4.It may preferably be provided that the composition comprises the matting component and the solvent in a weight ratio of the matting component to the solvent in a range from ≥1:4 to ≤4:5, preferably from ≥1:3 to ≤3:4, particularly preferably from ≥1:2 to ≤2:3.It may preferably be provided that the composition additionally comprises a blowing agent, wherein the blowing agent comprises at least one hydrocarbon selected from the group of the C 1 to C 4 hydrocarbons which is gaseous at 23° C.It may preferably be provided that the propellant comprises propane and butane, preferably in a range of:≥30% by weight to ≤60% by weight, preferably ≥40% by weight to ≤50% by weight, particularly preferably ≥42% by weight to ≤47% by weight, of propane;≥40% by weight to ≤70% by weight, preferably ≥50% by weight to ≤60% by weight, and particularly preferably ≥52% by weight to ≤57% by weight of butane, where butane is an n-butane, an isobutane, a tert-butane or a mixture of at least n-butane, isobutane and / or tert-butane, and preferably a mixture of n-butane and isobutane.It has surprisingly been shown that the composition can be applied to the surface particularly easily and uniformly with the aid of the abovementioned blowing agent and at the same time a sufficient amount of matting agent can be applied.Specific embodiments of the invention will be described below. It has surprisingly been shown that such compositions can each produce the desired elevations particularly well, so that particularly good, accurate and low-error feature-based tracking can be carried out.It may preferably be provided that the composition comprises the blowing agent, based on the composition, in a range of ≥35% by weight to ≤85% by weight, preferably ≥45% by weight to ≤75% by weight, more preferably ≥55% by weight to ≤65% by weight.It may preferably be provided that the sprayable composition is under a pressure of ≥100 kPa to ≤1000 kPa, preferably of ≥200 kPa to ≤800 kPa, more preferably of ≥300 kPa to ≤600 kPa, and particularly preferably of ≥400 kPa to ≤500 kPa.The invention further proposes a device comprising the composition according to the invention.Preferably, it can be provided that the device is a spray device, preferably a spray can. It has surprisingly been shown that the composition can be processed and stored in such a particularly good manner.The composition according to the invention can preferably be used to form the surface coating according to the invention.The use can preferably be effected for optical surface measurement, preferably for 3D scanning of objects, in particular of objects with planar surfaces.The invention is explained in more detail below with reference to preferred examples and figures.They show FIG. 1 schematically shows the result of surface measurement of a coating obtained according to Comparative Example 1, FIG. 2 schematically shows the result of surface measurement of a coating obtained according to Comparative Example 2, FIG. 3 schematically shows the result of a surface measurement of a coating obtained according to Example 1, FIG. 4 schematically shows the result of a surface measurement of a coating obtained according to Example 2; and FIG. 5 schematically shows the result of a surface measurement of a coating obtained according to Example 3.Comparative Example 124 g of cyclododecane and 56 g of isopropanol were mixed and introduced into a pressurized spray can. The can was then filled under pressure with 200 g of a mixture of 42% by weight of propane and 55% by weight of n-butane (remainder isobutane and / or isopentane). The spray can was shaken vigorously and the composition was sprayed onto a surface at a distance of 20-30 cm.The topography of the surface was measured with a digital microscope (Keyence VHX 6000). The results are shown in FIG. 1, in which the topography of the measured surface has been schematically represented in gray levels as a perspective view, the scale or dimensions in the three spatial directions being indicated in the image.It can be seen that a very uniform surface is obtained with the composition according to Comparative Example 1, the surface not having any elevations which would be detectable by an optical scanner.Comparative Example 240 g of cyclododecane and 78 g of acetone were mixed and placed in a pressurized spray can. The can was then charged under pressure with 191 g of the mixture of propane and butane. The spray can was shaken vigorously and the composition was sprayed onto a surface at a distance of 20-30 cm.The topography of the surface was measured as in Comparative Example 1. The results are shown in Fig. 2.It can be seen that with the composition according to Comparative Example 2 an nonuniform surface is obtained, the surface having very few elevations, which, however, cannot be detected by an optical scanner. Without being bound to a theory, it is assumed that the basically very inhomogeneous surface does not allow the elevations to be detected in detail by the scanner.Example 140 g of cyclododecane, 17 g of cyclopentane and 60 g of acetone were mixed and placed in a pressurized spray can. The can was then charged under pressure with 191 g of the mixture of propane and butane. The spray can was shaken vigorously and the composition was sprayed onto a surface at a distance of 20-30 cm.The topography of the surface was measured as in Comparative Example 1. The results are shown in Fig. 3.It can be seen that a more uniform surface was obtained with the composition according to Example 1 than in Comparative Example 2, the surface having elevations which can be detected at least partially by an optical scanner.Example 240 g of cyclododecane, 14 g of n-pentane and 60 g of acetone were mixed and placed in a pressurized spray can. The can was then charged under pressure with 191 g of the mixture of propane and butane. The spray can was shaken vigorously and the composition was sprayed onto a surface at a distance of 20-30 cm.The topography of the surface was measured as in Comparative Example 1. The results are shown in Fig. 4.It can be seen that with the composition according to Example 2, as well as with Example 1, a more uniform surface was obtained than in Comparative Example 2, the surface having elevations which are more numerous and in particular higher than those obtained with Example 1. These can be detected particularly well with an optical scanner.Example 340 g of cyclododecane, 18 g of butanone (methyl ethyl ketone) and 60 g of acetone were mixed and placed in a pressurized spray can. The can was then charged under pressure with 191 g of the mixture of propane and butane. The spray can was shaken vigorously and the composition was sprayed onto a surface at a distance of 20-30 cm.The topography of the surface was measured as in Comparative Example 1. The results are shown in Fig. 5.It can be seen that a more uniform surface was obtained with the composition according to Example 3 as well as with Example 1 than in Comparative Example 2, wherein the surface has elevations which, although less frequent than in Example 2, have in particular a comparable height as in Example 2. These can likewise be detected well with an optical scanner.

Claims

A surface coating, wherein the surface coating comprises a sublimable matting component and has elevations detectable by an optical scanner.The surface coating according to claim 1, wherein the elevations ≥ 50 μm protrude beyond a surface of the surface coating in a region surrounding the elevation, preferably ≥ 60 μm to ≤ 500 μm, more preferably ≥ 70 μm to ≤ 400 μm, more preferably ≥ 80 μm to ≤ 300 μm, more preferably ≥ 90 μm to ≤ 250 μm, particularly preferably ≥ 100 μm to ≤ 200 μm.The surface coating according to any one of claims 1 or 2, wherein the elevations are ≥ 50 μm thick than the surface coating in a region surrounding the elevation, preferably ≥ 60 μm to ≤ 500 μm, more preferably ≥ 70 μm to ≤ 400 μm, more preferably ≥ 80 μm to ≤ 300 μm, more preferably ≥ 90 μm to ≤ 250 μm, particularly preferably ≥ 100 μm to ≤ 200 μm.The surface coating according to any one of claims 1 to 3, wherein the protrusions have an average diameter in a range from ≥ 5 μm to ≤ 300 μm, more preferably ≥ 10 μm to ≤ 250 μm, more preferably ≥ 20 μm to ≤ 200 μm, more preferably ≥ 30 μm to ≤ 175 μm, more preferably ≥ 40 μm to ≤ 150 μm, particularly preferably ≥ 50 μm to ≤ 125 μm.The surface coating according to any one of claims 1 to 4, wherein the surface coating has ≥ 0.1 elevations / mm 2 to ≤ 100 elevations / mm 2 based on the surface of the surface coating, preferably ≥ 1 elevation / mm 2 to ≤ 100 elevations / mm 2, more preferably ≥ 2 elevations / mm 2 to ≤ 80 elevations / mm 2, more preferably ≥ 3 elevations / mm 2 to ≤ 70 elevations / mm 2, more preferably ≥ 4 elevations / mm 2 to ≤ 60 elevations / mm 2, particularly preferably ≥5 elevations / mm 2 to ≤100 elevations / mm 2.The surface coating according to any one of claims 1 to 5, wherein the surface coating has a layer thickness in a range from ≥ 0.5 μm to ≤ 30 μm, preferably from ≥ 1 μm to ≤ 25 μm, more preferably from ≥ 2 μm to ≤ 20 μm, and particularly preferably from ≥ 3 μm to ≤ 30 μm.The surface coating of any one of claims 1 to 6, wherein the surface coating consists of the sublimable matting component.The surface coating of any one of claims 1 to 7, wherein the sublimable matting component is a cyclic hydrocarbon solid at 20°C.The surface coating of any one of claims 1 to 8, wherein the sublimable matting component is selected from the group consisting of cyclododecane, adamantane and mixtures thereof, preferably wherein the sublimable matting component is cyclododecane.A composition for producing a surface coating according to any one of claims 1 to 9, comprising a sublimable matting component and a solvent, wherein the solvent comprises a first solvent and a second solvent, wherein the first solvent is a hydrocarbon having a boiling point of ≥ 25°C, a mixture of hydrocarbons having a lowest boiling point of ≥ 25°C, or a ketone having a boiling point of ≥ 70°C, and the second solvent is a ketone having a boiling point of ≥ 40°C.The composition of claim 10, wherein the matting component is a cyclic hydrocarbon solid at 20°C.The composition according to any one of claims 10 or 11, wherein the sublimable matting component is selected from the group consisting of cyclododecane, adamantane and mixtures thereof, preferably wherein the sublimable matting component is cyclododecane.The composition according to any one of claims 10 to 12, wherein the first solvent is selected from the group consisting of n-pentane, isopentane, cyclopentane, hexane, cyclohexane, heptane, cycloheptane, octane, petroleum ether 30-40, petroleum ether 40-60, petroleum ether 40-65, petroleum ether 40-80, petroleum ether 40-100, butanone or mixtures thereof, wherein the first solvent is preferably selected from n-pentane, cyclopentane, butanone and mixtures thereof, particularly preferably wherein the second solvent is n-pentane.The composition according to any one of claims 10 to 13, wherein the second solvent is selected from the group consisting of acetone, butanone, cyclohexanone, methyl isobutyl ketone, and mixtures thereof, wherein the second solvent is preferably selected from acetone, butanone and mixtures thereof, particularly preferably wherein the second solvent is acetone.The composition of any one of claims 10 to 14, wherein the first solvent is selected from n-pentane and the second solvent is selected from acetone.The composition according to any one of claims 10 to 15, wherein the solvent comprises the first solvent and the second solvent in a weight ratio of the first solvent to the second solvent in a range of ≥ 1:10 to ≤ 2:1, preferably ≥ 1:9 to ≤ 1:1, more preferably ≥ 1:8 to ≤ 1:2, more preferably ≥ 1:7 to ≤ 1:3, more preferably ≥ 1:6 to ≤ 1:4, and particularly preferably ≥ 1:5 to ≤ 1:4.The composition according to any of claims 10 to 16, wherein the composition comprises the matting component and the solvent in a weight ratio of the matting component to the solvent in a range from ≥ 1:4 to ≤ 4:5, preferably from ≥ 1:3 to ≤ 3:4, particularly preferably from ≥ 1:2 to ≤ 2:3.The composition of any one of claims 10 to 17, wherein the composition additionally comprises a blowing agent, wherein the blowing agent comprises at least one hydrocarbon selected from the group of C 1 to C 4 hydrocarbons that is gaseous at 23°C.Composition according to claim 18, wherein the propellant comprises propane and butane, preferably based on the propellant in a range of: - ≥ 30 wt.% to ≤ 60 wt.%, preferably ≥ 40 wt.% to ≤ 50 wt.%, particularly preferably ≥ 42 wt.% to ≤ 47 wt.% propane; - ≥ 40 wt.% to ≤ 70 wt.%, preferably ≥ 50 wt.% to ≤ 60 wt.%, and particularly preferably ≥ 52 wt.% to ≤ 57 wt.% butane, wherein butane is an n-butane, an isobutane, a tert-butane or a mixture of at least n-butane, isobutane and / or tert-butane, and preferably a mixture of n-butane and isobutane.Composition according to any one of claims 18 or 19, wherein the composition comprises the propellant, based on the composition, in a range ≥ 35 wt.% to ≤ 85 wt.%, preferably ≥ 45 wt.% to ≤ 75 wt.%, more preferably ≥ 55 wt.% to ≤ 65 wt.%.The composition according to any one of claims 18 to 20, wherein the sprayable composition is under a pressure of ≥ 100 kPa to ≤ 1000 kPa, preferably of ≥ 200 kPa to ≤ 800 kPa, more preferably of ≥ 300 kPa to ≤ 600 kPa, and most preferably of ≥ 400 kPa to ≤ 500 kPa.Device comprising a composition according to any one of claims 10 to 21.The device according to claim 22, wherein the device is a spray device, preferably a spray can.Use of the composition according to any one of claims 10 to 21 for forming a surface coating according to any one of claims 1 to 9.Use of the composition according to any of claims 10 to 21 or of the surface coating according to any of claims 1 to 9 for optical surface measurement, preferably for 3D scanning of objects, in particular objects with planar surfaces.

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