TEMPORARY PROTECTIVE COATING FOR OPTICAL ELEMENTS

Description

[0001] The invention relates to a lacquer composition from which a protective lacquer can be produced by polymerization, and to the use of the lacquer composition as a temporary protective lacquer for optical surfaces of optical elements. The invention further relates to an optical element comprising the protective lacquer.

[0002] Complex optical components, such as those used in data glasses for displaying image information, often contain various functional surfaces in close proximity and within a very small space. For example, the transmissive coupling surface may be located directly next to a reflective surface. During the manufacturing process of such optical elements, non-functional surfaces are typically coated with an absorber coating, such as a highly absorbent black coating, designed to eliminate stray light. The absorber coating is also preferably applied to highly reflective surfaces to protect them from environmental influences.

[0003] State-of-the-art compositions are known from DE 10 2012 210185 A1 and EP 2 065 414 A1.

[0004] The production and finishing of such optical elements is difficult, among other things, because on the one hand, reflective and non-functional surfaces must be coated with the absorber lacquer with sharp edges, and on the other hand, transmissive surfaces, such as an input coupling surface and any existing output coupling surface, must not be contaminated with the absorber lacquer in order to avoid loss of transmission or the creation of image errors.

[0005] The object of the invention is therefore to reliably protect optical surfaces of optical elements during their manufacturing process against chemical and physical influences, whereby the protection can be applied precisely and removed again without leaving residue.

[0006] According to the invention, this object is achieved by a coating composition comprising (A) 20 - 79.9 wt.%, based on the total weight of the composition, of a thiol compound having two or more thiol groups, (B) 20 - 79.9 wt.%, based on the total weight of the composition, of a compound having two or more carbon-carbon double bonds and (C) 0.2 - 10 wt.%, based on the total weight of the composition, of a

[0007] A release agent having at least one alkyl radical having 4-20 carbon atoms, wherein the alkyl radical is unsubstituted or substituted by fluorine and the alkyl radical is bonded to a functional group, wherein the release agent is selected from a group consisting of alkyl mercaptan, alkene, primary alkylamine, secondary alkylamine, tertiary alkylamine, alkyl phosphate, dialkyl phosphate and trialkyl phosphate.

[0008] The object is further achieved by using this coating composition as a protective coating, which can be removed by peeling off, on an optical surface of an optical element during its manufacture. The object is further achieved by an optical element with an optical surface, wherein the protective coating is applied to at least part of the optical surface.

[0009] Surprisingly, the coating composition according to the invention can be used to produce a protective coating that offers an excellent balance between adhesion to the optical surfaces of optical elements for their protection and removability. The optical surface of optical elements is reliably sealed against subsequent processes such as coating or cleaning, which often involve wet processing steps or treatments in a vacuum or using plasma. The protective coating is stable against subsequent process steps such as thermal treatments or chemical reagents and solvents. Furthermore, the protective coating does not chemically attack the optical surfaces of conventional optical elements and can be easily removed (peeled off) after processing by mechanical means.

[0010] The developed polymer system is based on the principle of radical polymerization of thiol-ene systems. According to the invention, a defined amount of a release agent is added to these systems. The release agent is a compound containing one or more alkyl radicals with 4-20 carbon atoms on a functional group. Although not bound to the release agent, it is assumed that the release agent accumulates at the interface during the curing process, allowing the protective coating to be easily removed from the optical surface to be protected.

[0011] "Containing" a compound, for example, a thiol compound, is understood as usual to mean that the composition contains or comprises one or more of these compounds. In this sense, the invention relates to a composition comprising one or more thiol compounds, each containing two or more thiol groups, one or more compounds containing two or more carbon-carbon double bonds, and one or more separating agents, each containing one or more alkyl radicals having 4-20 carbon atoms, wherein the alkyl radical is bonded to a functional group. An alkyl radical or an alkyl group is understood to mean a group of carbon and hydrogen atoms that is not aromatic, whereby an alkyl radical within the meaning of the invention can also contain one or more double bonds, i.e., can be an alkane or alkene radical. The alkyl group or the alkyl radical can be unsubstituted or substituted by fluorine.Among the fluorinated alkyl radicals, partially fluorinated alkyl radicals are preferred, ie only some of the hydrogen atoms are substituted by fluorine.

[0012] Component (A) is a thiol compound with two or more thiol groups (-SH groups). Preferred thiol compounds are mercaptoesters, and in particular mercaptoesters with two or more ester groups and two or more thiol groups. Preferred mercaptoesters are mercaptoacetates, 2- and 3-mercaptopropionates, which exhibit advantageous reactivity in combination with the other components of the coating composition according to the invention. Further preferred are mercaptoesters whose carboxylic acid groups are esterified with polyfunctional alcohols. Preferred polyfunctional alcohols are the polyfunctional alcohols listed below in the form of their mercaptoesters.Preferred are mercapto esters having 3 or more thiol groups and 3 or more ester groups, in particular pentaerythritol tetra-(3-mercaptopropionate) (PTMP), trimethylolpropane tri-(3-mercaptopropionate) (TPMP), ethylene glycol di-(3-mercaptopropionate) (GDMP), pentaerythritol tetra-(mercaptoacetate) (PTMA), trimethylolpropane tri-(mercaptoacetate) (TPMA), ethylene glycol di-(mercaptoacetate) (GDMA), tris-[2-(3-mercaptopropionyloxy)-ethyl]-isocyanurate (TEMPIC) and tris-[2-(2-mercaptopropionyloxy)-ethyl]-isocyanurate (TETLIC). Tris-[2-(3-mercaptopropionyloxy)-ethyl]-isocyanurate and trimethylolpropane-tri-(3-mercaptopropionate) have proven to be particularly advantageous.

[0013] In a further preferred embodiment of the invention, component (A) is a thioether having two or more thiol groups. Such a thioether thus contains the RSR' group and two or more free SH groups. An example of a thioether is 2,3-bis(2-mercaptoethylsulfanyl)propane-1-thiol.

[0014] Component (A) is present in an amount of 20-79.9 wt.%, based on the total weight of the coating composition. 25-74.9 wt.% is preferred, especially 30-69.9 wt.%.

[0015] Component (B) is a compound with two or more carbon-carbon double bonds. Compounds with a terminal carbon-carbon double bond, such as acrylates and methacrylates, vinyl and vinyloxy compounds, and especially allyl derivatives, are particularly preferred with regard to reactivity. Preferred among these are allyl esters of phthalic acid, isophthalic acid, and terephthalic acid, allyl ethers of pentaerythritol and trimethylolpropane, and 2,4,6-triallyloxy-1,3,5-triazine. 1,3,5-triallyl-1,3,5-triazine-2,4,6-trione can be used with particular advantage. 1,3,5-Triallyl-1,3,5-triazine-2,4,6-trione can be used particularly in combination with the above-mentioned mercaptoesters, and here in particular together with tris-[2-(3-mercaptopropionyloxy)-ethyl]-isocyanurate and / or trimethylolpropane tri-(3-mercaptopropionate). Component (B) is present in an amount of 20-79.9 wt.%, based on the total weight of the coating composition.Preferred are 25 - 74.9 wt.%, in particular 30 - 69.9 wt.%.

[0016] It is understood that components (A), (B), and (C) of the coating composition according to the invention, optionally with other components of the composition, together make up 100% by weight. The skilled person will thus select amounts of the 20-79.9% by weight of the thiol compound having two or more thiol groups (A), the 20-79.9% by weight of the compound having two or more carbon-carbon double bonds (B), and the 0.1-10% by weight of release agent (C) such that, together with any other components present, such as additives, fillers, solvents, oligomers, etc., a total of 100% by weight is formed.

[0017] A central role in the coating composition according to the invention is played by component (C), the release agent, which has an alkyl radical with 4-20 carbon atoms, where the alkyl radical is bonded to a functional group. The release agent can contain several alkyl groups, each of which has 4-20 carbon atoms and is bonded to the functional group. This release agent ensures that the protective coating produced from the coating composition can be easily removed, particularly from the optical surfaces of optical elements.

[0018] The alkyl radical of component (C) can be saturated or unsaturated. It can also be unbranched, branched, or cyclic. Examples of saturated alkyl radicals are butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, and eicosyl. 1-Alkyl radicals are preferred. In a preferred embodiment of the invention, the release agent (C) has one or more alkyl radicals, where the one alkyl radical has 7-20 carbon atoms or the multiple alkyl radicals together have 7-20 carbon atoms. Examples of a release agent with 8 carbon atoms would be octylamine, dibutylamine, or dibutyl phosphate. The multiple alkyl radicals can have the same or different lengths.A dialkyl compound as a release agent with a total of 8 carbon atoms could, for example, have one radical with 2 and one with 6 carbon atoms, one radical with 3 and one with 5 carbon atoms, or two radicals with 4 carbon atoms. Particular preference is given to release agents with one or more alkyl radicals, where the one or more alkyl radicals together have 8-16 carbon atoms. The most preferred release agents are dodecylamine and dibutyl phosphate.

[0019] The release agent can be present as an additive in the coating composition, i.e., it is not incorporated into the polymer. According to the invention, the amines and phosphates, i.e., the release agents, are alkylamines such as primary alkylamines (monoalkylamine), secondary alkylamines (dialkylamine), or tertiary alkylamines (trialkylamine), alkyl phosphates, dialkyl phosphates, and trialkyl phosphates. Among these alkylamines present as additives, dodecylamine, tetradecylamine, and hexadecylamine are particularly preferred.

[0020] A release agent present as an additive usually forms a residue film after the polymer in the form of the protective varnish has been removed, which can be wiped off with a cloth, for example, during the manufacturing process.

[0021] The release agent can particularly advantageously have a reactive functionality, i.e. it is polymerized in during the polymerization of the coating composition, thereby enabling particularly low-residue removal of the protective coating. Preferably, the functional group here is a thiol or mercaptan group (-SH) or a carbon-carbon double bond, i.e. the release agent is an alkyl mercaptan or an alkene. In these, the alkyl radical can again be structured as described above. Preference is given to 1-alkyl mercaptans having 7-20 carbon atoms, in particular having 8-18 carbon atoms and most preferably having 10-16 carbon atoms. Particularly preferred release agents are 1-decyl mercaptan, 1-dodecyl mercaptan, 1-tetradecyl mercaptan and 1-hexadecyl mercaptan. Suitable alkenes are particularly those having a terminal double bond, i.e. the functional group is a vinyl group.Thus, the separating agent may preferably be a 1-alkene having 9-22 carbon atoms, especially 10-20 carbon atoms and most preferably 12-18 carbon atoms, especially 1-dodecene, 1-tetradecene, 1-hexadecene and 1-octadecene.

[0022] Another possibility is a chemically crosslinked release agent, e.g., an oligomeric (prepolymeric) polythiol, which is obtained by reacting a 1-mercaptoalkane with a substoichiometric amount of a suitable diisocyanate. It is also possible to use prepolymers of polyfunctional thiols by reacting them with a substoichiometric amount of a 1-alkyl isocyanate, such as octadecyl isocyanate.

[0023] The release agent is present in the coating composition according to the invention in an amount of 0.2-10 wt.%, based on the total weight of the composition. 0.2-5 wt.% is preferred, in particular 0.5-3 wt.%.

[0024] A preferred paint composition includes: (A) 30-69.8% by weight, based on the total weight of the composition, of a thiol compound having two or more thiol groups, (B) 30-69.8% by weight, based on the total weight of the composition, of a compound having two or more carbon-carbon double bonds, and (C) 0.2-5% by weight, based on the total weight of the composition, of a release agent having an alkyl radical having 4-20 carbon atoms, wherein the alkyl radical is unsubstituted or substituted by fluorine and the alkyl radical is bonded to a functional group.

[0025] The lacquer can be designed to be relatively thin in order to be able to fill an optical surface, for example in the form of a depression, as quickly and completely as possible. In other embodiments, it can be advantageous to set a higher viscosity in order to achieve, for example, selective coverage of an optical surface. For higher viscosity, an oligomer can be added to the lacquer composition in an advantageous embodiment. For the purposes of the invention, an oligomer is understood to be an organic compound made up of repeating units of monomers, where the number of monomers (sum of all monomers) is on average 3-100, in particular 5-70. This oligomer is also referred to below as a prepolymer.

[0026] In a preferred embodiment of the invention, component (A) is an oligomer for increased viscosity. Therefore, the coating composition preferably comprises 20-79.9 wt.% of an oligomer or prepolymer, based on the total weight of the coating composition, in particular 30-69.5 wt.%.

[0027] The oligomer is preferably an oligomeric thiourethane, especially with free thiol groups. Thiourethanes are known to those skilled in the art. They can be prepared from a thiol and an isocyanate. Preferred are oligomeric thiourethanes made from a mercaptoester with two or more thiol groups (mercaptoester monomer) and an isocyanate with two or more isocyanate groups (isocyanate monomer). Further preferred are oligomeric thiourethanes made from a thioether with two or more thiol groups and an isocyanate with two or more isocyanate groups. Examples of isocyanates are TDI (toluene-2,4-diisocyanate), HMDI (hexamethylene diisocyanate), and MDI (methylene diphenyl diisocyanate).

[0028] The total number of thiol and isocyanate monomers contained in the oligomer is 3 - 100 on average. In this sense, for example, the oligomer PTMP - XDI - PTMP - XDI - PTMP would comprise 5 monomers. Preferred oligomers are pentaerythritol tetra-(3-mercaptopropionate) (PTMP) with xylylene diisocyanate (XDI), pentaerythritol tetra-(3-mercaptopropionate) with norbornyl diisocyanate (NBDI), or pentaerythritol tetra-(3-mercaptopropionate) with isophorone diisocyanate (IPDI), as well as oligomers of trimethylolpropane tri-(3-mercaptopropionate) (TPMP) with xylylene diisocyanate, trimethylolpropane tri-(3-mercaptopropionate) with norbornyl diisocyanate (NBDI), or trimethylolpropane tri-(3-mercaptopropionate) with isophorone diisocyanate (IPDI). The ratio of mercaptopropionate to diisocyanate in these oligomers is preferably 20:1 to 5:1 to ensure complete conversion of the isocyanate groups. Example PTMP / XDI:

[0029] PTMP Molecular weight 488 g / mol, 4 SH groups XDI Molecular weight 188 g / mol, 2 NCO groups

[0030] Preparation of the oligomers: The polythiol is reacted completely with the isocyanate in stoichiometric excess under protective gas. Monitoring is carried out by IR spectroscopy (NCO band at approx. 2262 cm -1 , detection limit at 50 µm layer thickness is approx. 0.02 wt% free NCO). Prepolymer PTMP / XDI 100+10: 13.0% of the SH groups are converted. Prepolymer PTMP / XDI 100+15: 19.5% of the SH groups are converted. Prepolymer PTMP / XDI 100+20: 26.0% of the SH groups are converted.

[0031] The ratio of PTMP to XDI is based on the viscosity of the prepolymers / oligomers that result during the reaction, which thus significantly influence the viscosity of the resulting coating composition.

[0032] In a preferred embodiment of the invention, the thiol compound is thus an oligomeric thiourethane obtainable by reacting at least one mercaptoester having two or more ester groups and two or more thiol groups with at least one di- or polyisocyanate, the resulting oligomeric thiourethane having two or more free thiol groups. Alternatively, in addition to a monomeric mercaptoester compound, an oligomeric thiourethane is added to the coating composition, the oligomeric thiourethane in turn being obtainable by reacting at least one mercaptoester having two or more ester groups and two or more thiol groups with at least one di- or polyisocyanate, the oligomeric thiourethane having two or more free thiol groups. The oligomeric thiourethane can also be a mixture of two or more oligomeric thiourethanes. The oligomeric thiourethanes are preferably each obtainable as described above.An added oligomer or prepolymer is preferably added in an amount of 10-30 wt.% based on the total weight of the coating composition.

[0033] In a further advantageous embodiment, a filler is additionally added to the coating composition according to the invention, which can reduce the shrinkage of the protective coating during curing. This prevents, in particular, detachment of the protective coating from a surface during curing, so that, for example, in the case of an optical element, no traces of a subsequently applied absorber coating can get between the optical surface and the applied protective coating. 5-25 wt.% filler, based on the total weight of the coating composition, in particular 10-20 wt.%, have proven advantageous. A preferred filler is quartz powder or fused silica powder, in particular silanized quartz powder or fused silica powder, preferably with an average particle size of 4-6 µm. Alkylsilanes, glycidylsilanes, acrylic / methacrylic silanes, and mercaptosilanes can be used as the silanization coating.Polymers, in particular polyvinyl acetate or ketone resins in pure or hydrogenated form, are also preferred as fillers, as this allows the protective coating to be produced to be kept particularly flexible.

[0034] The coating composition according to the invention may further contain conventional additives, for example stabilizers and photoinitiators. Stabilizers are radical scavengers that ensure that the mixture of the polyfunctional thiol compound and the compound with two or more carbon-carbon double bonds does not polymerize spontaneously. Sterically hindered hydroquinones or phenols are preferably used; particularly preferred stabilizers are tert-butylhydroquinone and 2,6-di-tert-butyl-4-methylphenol (butylhydroxytoluene, BHT). Amounts of 0.2-3 wt. %, based on the total weight of the coating composition, have proven particularly effective as stabilizers.

[0035] Solvents can generally be used to regulate the processing viscosity or to ensure uniform application after application of the protective coating. It is preferred that the coating composition according to the invention contains little organic solvent to avoid damaging optical surfaces. The coating composition according to the invention comprises, in particular, less than 1 wt.%, based on the total weight of the composition, of organic solvent, particularly preferably less than 0.5 wt.%, most preferably less than 0.1 wt.%, and most preferably the coating composition is solvent-free.

[0036] For the purposes of the invention, an organic solvent is, as usual, a carbon-containing compound that can dissolve gases, liquids, or solids without chemical reactions occurring between the solvent and the dissolved substance. Organic solvents are well known to those skilled in the art.

[0037] In terms of rapid process control, UV curing of the coating composition according to the invention is particularly advantageous, as it allows sufficient curing to be achieved in a relatively short period of time. In principle, thermal curing is also possible, or a combination of these. For UV curing, customary photoinitiators are added before polymerization, for example α-hydroxyketones, such as Irgacure 1116, Irgacure 1173 and Irgacure 2959, Irgacure 1173 is preferred. Also suitable are α-aminoketones, such as Irgacure 369, Irgacure 379, Irgacure 907 and Irgacure 1300, benzyldimethylketals, such as Irgacure 651, phenylglyoxylates, such as B. Irgacure 754, mono-acylphosphines, such as Irgacure TPO, and bis-acylphosphines, such as Irgacure 819 and Irgacure 2100, as well as benzophenones, can be used. For thermal curing, peroxides such as di-tert-butyl peroxide or dibenzoyl peroxide, as well as azo compounds such as azobisisobutyronitrile, are preferred.

[0038] In addition, other additives, such as plasticizers or synthetic resins, can be added to adjust the viscosity to the desired application. Furthermore, it may be advantageous to add a dye or color pigment to the coating composition according to the invention to make the protective coating more visible, for example, in the manufacturing process of optical elements. Seriplas Red X3B-TP and Sudan Blue have proven particularly suitable. The dyes or pigments should be sufficiently translucent, i.e., transparent, at the respective excitation wavelength, e.g., 365 nm.

[0039] The invention further relates to a process for producing a protective coating, comprising the steps of polymerizing the coating composition according to the invention, for example thermally or with the aid of light. The process according to the invention for producing a protective coating comprises, in particular, the steps of mixing the coating composition according to the invention with a photoinitiator and subsequently irradiating it with light having a wavelength of ≤ 450 nm, whereby the composition polymerizes and cures. Alternatively, the composition according to the invention can be admixed with a conventional free-radical initiator and heated (thermal polymerization).

[0040] The invention further relates to the use of the coating composition according to the invention as a protective coating, in particular as a protective coating on an optical surface of an optical element, in particular during the production of the optical element. The invention also relates to a protective coating producible by polymerizing the coating composition according to the invention.

[0041] The invention also relates to an optical element with an optical surface, wherein at least a portion of the optical surface comprises a protective lacquer, producible by polymerizing the lacquer composition according to the invention. If a portion of a surface comprises a protective lacquer, this is understood within the meaning of the invention to mean that at least a portion of the surface is coated with a protective lacquer. It is preferred that the entire surface is coated or covered with the protective lacquer. In a preferred embodiment of the invention, the optical surface is delimited by a circumferential raised edge, and the protective lacquer is introduced into the resulting recess.

[0042] The optical surface of the optical element can be selectively coated with the protective lacquer, which can be produced from the lacquer composition according to the invention. The surrounding area can be designed in such a way that the application and the protective function of the protective lacquer are favored. For example, the surface can be extended to ensure the protective function beyond the edge of the layer. It can also be advantageous to design the surrounding edge as a circumferential elevation, so that a depression is formed, for example in the form of a trough, which can hold the lacquer. This creates a defined plug that covers both the layer to be protected and the bordering side walls. The liquid lacquer or the liquid reactive resin can then be poured into the depression and cured after the optical layer has been applied.After the component has been completely processed, the plug can be removed along with any lacquers and layers applied to it, leaving the previously applied optical layer intact.

[0043] To ensure the protective function of the peelable coating, it can be advantageous to apply the protective coating beyond the edge of the actual functional layer. To achieve uniform adhesion or demolding, the functional layer can also be made larger, so that the protective coating extends beyond the optically used area of ​​the layer but covers a uniform surface. This can also be achieved in the case of a recess or trough by having the optical layer cover the entire inner surface of the trough.

[0044] The protective coating preferably has a thickness of 0.2–2.5 mm. Thickness refers to the maximum thickness, for example, in the case of a layered protective coating, the greatest height of the layer. A thickness of 0.5–1.5 mm is particularly preferred.

[0045] The protective coating, which can be produced by polymerizing the coating composition according to the invention, can be removed again by peeling it off. To simplify subsequent removal, it can be helpful to polymerize a suitable aid into the protective coating. Advantageously, a loop or pin can be embedded, allowing the protective coating to be peeled off.

[0046] The optical element can be made of conventional optical materials. These include mineral glass and ceramic materials, but also, above all, polymers. Examples include thermoplastics such as PMMA (polymethyl methacrylate), PET (polyethylene terephthalate), PC (polycarbonate), COP / COC (cycloolefin polymers / cycloolefin copolymers), PS (polystyrene), PA (polyamides), as well as thermosets such as ADC (allyl diglycol carbonate), PUR (polyurethanes), PU (polyureas), PTU (polythiourethanes), and elastomers such as LSR (liquid silicone rubber).

[0047] The optical element can, for example, be a lens, prism, an optical element of imaging optics, projection or recording optics, part of a microscope, etc. In an advantageous embodiment of the invention, the optical element is designed as a spectacle lens for a display device that can be placed on the head of a user and generates an image, wherein the optical element has a front side and a back side, the optical surface is a coupling surface and the optical element has an output coupling section spaced from the coupling surface and a light guide channel that is suitable for guiding light bundles from pixels of the generated image, which are coupled into the optical element via the coupling surface of the optical element, in the optical element to the output coupling section, from which they are coupled out of the optical element.The coupling surface has a protective coating on at least part of its surface, which can be produced by polymerizing the coating composition according to the invention. The protective coating is a temporary coating, meaning it is used during the manufacturing process to protect optical surfaces, such as coupling surfaces, and is subsequently removed.

[0048] Furthermore, a display device is provided with a holding device that can be placed on the head of a user, an image generation module that is fastened to the holding device and generates an image, and an imaging optic that is fastened to the holding device and has an optical element according to the invention and that images the generated image when the holding device is placed on the user's head in such a way that the user can perceive it as a virtual image.

[0049] The imaging optics can comprise the optical element as the sole optical element. However, it is also possible for the imaging optics to comprise at least one additional optical element in addition to the optical element. The at least one additional optical element can be spaced apart from the optical element or directly connected to it (e.g., glued or cemented).

[0050] The display device can have a control unit that controls the image generation module. The image generation module can, in particular, have a planar image generator, such as an LCD module, an LCoS module, an OLED module, or a tilting mirror matrix. The image generator can have a plurality of pixels, which can, for example, be arranged in rows and columns. The image generator can be self-luminous or non-self-luminous. The image generation module can, in particular, be designed to generate a monochromatic or a multicolor image. The display device can have further elements known to those skilled in the art that are necessary for its operation.

[0051] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations indicated, but also in other combinations or in isolation, without departing from the scope of the present invention.

[0052] The invention is explained in more detail below by way of example with reference to the accompanying drawings, which also disclose essential features of the invention. For clarity, the figures are at least partially drawn to scale and proportion, and hatching is omitted. They show: Fig. 1 shows an embodiment of the display device according to the invention; Fig. 2 shows an enlarged partial sectional view of the optical element 1 according to the invention, including a schematic representation of the image generation module.

[0053] At the Fig. 1In the embodiment shown, the display device 1 according to the invention comprises a holding device 2 that can be placed on the head of a user and can be designed, for example, in the manner of a conventional spectacle frame, as well as a first and a second spectacle lens 3, 4 that are fastened to the holding device 2. The holding device 2 with the spectacle lenses 3, 4 can be designed, for example, as sports glasses, sunglasses and / or spectacles for correcting ametropia, wherein a virtual image can be projected into the user's field of vision via the first spectacle lens 3, as described below.

[0054] For this purpose, the display device 1 comprises an image generation module 5, which can be arranged in the area of ​​the right temple of the holding device 2, as shown in Fig. 1 is shown schematically. The image generation module 5 can be a planar image generation element 6 ( Fig. 2), such as an OLED, an LCD or an LCoS chip or a tilting mirror matrix, with a large number of pixels arranged, for example, in columns and rows.

[0055] The spectacle lenses 3 and 4, and in particular the first spectacle lens 3, are described only by way of example together with the display device 1 according to the invention. The spectacle lenses 3, 4, or at least the first spectacle lens 3, are each designed individually as a spectacle lens 3, 4 according to the invention or as an optical element according to the invention. The optical element according to the invention can also be used in a context other than with the display device 1 described here. Therefore, if the optical element is designed as a spectacle lens, it can of course also be designed as a second spectacle lens 4.

[0056] As best seen from the enlarged, schematic partial sectional view in Fig. 2As can be seen, the display device 1 has an imaging optics 7, which contains an optical element 8 arranged between the image generating element 6 or the image generator 6 and the first spectacle lens 3. Furthermore, the first spectacle lens 3 itself also serves as part of the imaging optics 7.

[0057] A light beam 9 can emanate from each pixel of the imager 6. By appropriately controlling the pixels of the imager 6 by means of a control unit 10, which can be part of the image generation module 5, the desired image can be generated. Fig. 2 The beam path of a light beam is shown as a representative of the light bundles 9, so that the light beam 9 is also referred to below.

[0058] The light beam 9 emanating from the imager 6 passes through the optical element 8 and enters the first spectacle lens 3 via a coupling section 11 or coupling surface 11 (here, the front side of the first spectacle lens 3) and is guided therein along a light guide channel 12 to a coupling-out section 13. The coupling-out section 13 has a plurality of reflective deflection surfaces 14 (which can also be referred to as reflective facets) arranged next to one another, at which the light rays 9 are reflected toward a rear side 15 of the first spectacle lens 3, so that the light rays 9 exit the first spectacle lens 3 via the rear side 15. The coupling section 11 or the coupling surface 11 can also be connected directly to the spectacle lens 3. During the manufacturing process, the coupling surface 11 or the coupling section 11 is temporarily provided with the protective varnish according to the invention.

[0059] Thus, when a user wears the display device 1 according to the invention on his head as intended, he can perceive the image generated by the image generator 6 as a virtual image when looking at the output section 13. In the embodiment described here, the user must look approximately 40° to the right relative to the viewing direction G of a straight-ahead view. Fig. 2 For clarity, the pivot point 16 of the user's eye and the eyebox 17 or exit pupil 17 of the imaging optics 7 are shown. The eyebox 17 is the area provided by the display device 1 and in which the user's eye can move while still being able to see the generated image as a virtual image.

[0060] Although in the described embodiment the coupling is carried out via the front side of the first spectacle lens 3 and thus the coupling section 11 is formed on the front side of the first spectacle lens 3, it is also possible to carry out a coupling via the back side 15 of the first spectacle lens.

[0061] As shown in the schematic diagram in Fig. 2 As shown, both the back 15 and the front 18 of the first spectacle lens 3 are curved.

[0062] The optical element can be manufactured as follows: In a first step, a first semi-finished product is injection-molded from a thermoplastic polymer. The first semi-finished product can then be coated with an optically active layer in the area of ​​a microstructure. Known coating processes can be used for this purpose, such as chemical vapor deposition (CVD) or physical vapor deposition (PVD). The depressions resulting from the microstructuring, which extend from the second side into the semi-finished product, can be filled in a subsequent step to create a smooth, continuous second side. The same material used to produce the semi-finished product, or an optical putty or optical adhesive, can be used to fill the depressions. In particular, the composition according to the invention can be used.

[0063] In the manufacturing process described above, an optical surface, for example the coupling surface 11 or coupling section 11, can be provided with the protective lacquer according to the invention and the protective lacquer can be removed again during or after the process.

[0064] In the display device 1 according to the invention, the virtual image is projected into the user's field of vision via the first spectacle lens 3. Of course, it is also possible to project it via the second spectacle lens 4. Furthermore, the display device 1 can be designed such that information or virtual images are projected via both spectacle lenses 3, 4. The projecting can be done in such a way that a three-dimensional image impression is created. However, this is not absolutely necessary.

[0065] The holding device 2 does not have to be designed as a glasses-like holding device. Any other type of holding device is also possible, allowing the display device to be placed or worn on the user's head.

[0066] The spectacle lens can be constructed with two shells. However, it is also possible to manufacture the spectacle lens with a single shell or with more than two shells, e.g., at least three shells. In particular, the spectacle lens can be manufactured from one or two parts (which do not necessarily have to be shells) or from more than two parts.

[0067] The following examples illustrate the invention.

[0068] The following compositions are prepared by mixing the components of the respective examples at room temperature. The resulting compositions are then irradiated with UV-A light with a wavelength of approximately 365–400 nm, generated using a high-pressure mercury lamp, e.g., a Hönle Bluepoint 3, for approximately 60 s at 30–50 mW / cm² or 30 s at 100–150 mW / cm² (milliwatts per square centimeter). UV LEDs with wavelengths of 365 nm, 375 nm, 385 nm, 395 nm, or 405 nm can also be used as an alternative light source. UV LEDs with wavelengths of 365 nm, 385 nm, or 405 nm, e.g., a Hönle Bluepoint LED, are preferred. Example 1

[0069] 100 ME TEMPIC 47 ME TTT 5 ME Irgacure 1173 3 ME BHT 3 ME 1-dodecylamine 0.02 ME Seriplas Red X3B-TP Example 2

[0070] 100 ME PTMP 68 ME TTT 5 ME Irgacure 1700 3 ME 1-dodecylamine 2 ME BHT Example 3

[0071] 100 ME TEMPIC 100 ME Silbond 600 RST 47 ME TTT 4 ME Irgacure 1173 3 ME Zelec UN 2 ME BHT Example 4

[0072] 100 ME Prepolymer PTMP / XDI (100+12) 51 ME TTT 5 ME Zelec UN 4 ME Irgacure 1173 2 ME BHT Example 5

[0073] 90 ME Prepolymer / XDI (100+12) 46 ME TTT 20 ME Synthetic resin SK 2.5 ME Zelec UN 3 ME Irgacure 1173 2 ME BHT

[0074] Explanations: ME unit of mass BHT butylhydroxytoluene; 2,6-Di-tert-butyl-4-methylphenol Prepolymer PTMP / XDI (100+12) Prepolymer of pentaerythritol tetra(3-mercaptopropionate) and xylylene diisocyanate in the ratio 100+12 TEMPIC Tris[2-(3-mercaptopropionyloxy)ethyl]isocyanurate TPMP Trimethylolpropane tri(3-mercaptopropionate) TTT 1,3,5-Triallyl-1,3,5-triazine-2,4,6-trione Zelec UN Di-(n-dodecyl) hydrogen phosphate Synthetic resin SK Hydrogenated acetophenone-formaldehyde resin Irgacure 1173, Irgacure 1700 Photoinitiators Silbond 600 RST silanized quartz flour

[0075] Using the above-described coating compositions of Examples 1 to 5, rapidly curing protective coatings could be produced that provide good protection for optical surfaces and are easily removable.

Claims

1. A lacquer composition comprising (A) 20-79.9% by weight, based on the total weight of the composition, of a thiol compound having two or more thiol groups, (B) 20-79.9% by weight, based on the total weight of the composition, of a compound having two or more carbon-carbon double bonds and (C) 0.2-10% by weight, based on the total weight of the composition, of a separating agent having an alkyl radical having 4-20 carbon atoms, where the alkyl radical is unsubstituted or fluorine-substituted and the alkyl radical is bonded to a functional group, characterized in that the separating agent is selected from the group consisting of alkyl mercaptan, alkene, primary alkylamine, secondary alkylamine, tertiary alkylamine, alkyl phosphate, dialkyl phosphate and trialkyl phosphate.

2. The lacquer composition as claimed in claim, characterized in that the thiol compound (A) is a mercapto ester having two or more ester groups and two or more thiol groups or a thioether having two or more thiol groups.

3. The lacquer composition as claimed in claim 1 or 2, characterized in that component (A) is tris[2-(3-mercaptopropionyloxy)ethyl] isocyanurate or trimethylolpropane tri(3-mercaptopropionate) and / or component (B) is 1,3,5-triallyl-1,3,5-triazine-2,4,6-trione.

4. The lacquer composition as claimed in any of claims 1-3, characterized in that the thiol compound is an oligomeric thiourethane obtainable by reacting at least one mercapto ester having two or more ester groups and two or more thiol groups and / or a thioether having two or more thiol groups with at least one di- or polyisocyanate, where the oligomeric thiourethane has two or more free thiol groups.

5. The lacquer composition as claimed in any of claims 1-4, characterized in that the lacquer composition additionally contains 5-25% by weight, based on the total weight of the composition, of a filler.

6. The lacquer composition as claimed in any of claims 1-5, characterized in that the separating agent has an alkyl radical or multiple alkyl radicals, where the one or more alkyl radical(s) together have 7-20 carbon atoms.

7. A process for producing a protective lacquer, comprising the steps of mixing the lacquer composition as claimed in any of claims 1-6 with a photoinitiator and then irradiating it with light at a wavelength of ≤ 450 nm to cure the composition.

8. The use of a lacquer composition as claimed any of claims 1-6 as protective lacquer on an optical surface of an optics element in the production of the optics element.

9. An optics element having an optical surface, wherein at least part of the optical surface has a protective lacquer producible by polymerizing a lacquer composition as claimed in any of claims 1-6.

10. The optics element as claimed in claim 9, characterized in that the optical surface is bounded by a peripheral elevated edge and the protective lacquer is disposed in the depression that results therefrom.

11. The optics element as claimed in claim 9 or claim 10, characterized in that it is an optics element for a display device (1) that can be placed onto a user's head and produces an image, wherein the optics element has a front side (18) and a rear side (15), the optical surface is an input surface (11) and the optics element has an output section (13) spaced apart from the input surface (11) and a light-guiding channel (12) suitable for guiding beams of light (9) of pixels of the generated image that are input into the optics element (3) via the input surface (11) of the optics element (3) within the optics element (3) to the output section (13), from which they are output from the optics element (3).