Method for providing a substrate with a colouring and a functional colouring

Abstract

The invention relates to a method for providing a substrate with a colouring and a functional colouring, comprising the following steps (a) to (c) in this order: (a) supplying a substrate to be provided with a colouring and a functional colouring, wherein the substrate is produced from plastic glass and the substrate has a first main side and a second main side opposite the first main side and having a convex shape; (b) applying a colouring to both main sides of the substrate supplied in step (a); and (c) applying a functional colouring to both main sides of the substrate provided with a colouring on both main sides in step (b) by dip-coating, thus obtaining a substrate which is provided on both main sides with a colouring and a functional colouring.

Description

[0001] METHOD FOR PROVIDING A SUBSTRATE WITH

[0002] ONE COLOURING AND ONE FUNCTIONAL COLOURING

[0003] The present invention relates to a method for providing a substrate with a coloration and a functional coloration.

[0004] Self-tinting lenses, also called photochromic lenses, can react to UV light. Depending on the intensity of the UV light hitting the lens, it becomes dark or light. The darkening or lightening of the lens is made possible by a functional tint with which the lens is coated. The functional tint is caused by a photochromic dye, which reacts to UV light irradiation with a reversible change in its molecular structure and thus also in its absorption behavior. When the UV light irradiation subsides, the photochromic dye returns to its original molecular structure and thus also its original absorption behavior. A photochromic dye thus enables a reversible switching back and forth between a dark and a light tint.

[0005] In addition to functional tinting, the lens can also be tinted. This tinting gives the lens a specific hue, which is particularly desirable for sunglasses. In contrast to functional tinting, tinting uses dyes that—apart from their absorption properties—have no functional properties and are therefore referred to as non-functional dyes.

[0006] In the manufacturing processes established in the state of the art, the functional coloring is either incorporated directly into the glass material or applied to the glass material as an additional layer, for example, by spin coating. However, the coloring of such pretreated glass materials is often not reproducible. Furthermore, the coloring impairs the functional coloring, as the regions of the electromagnetic spectrum required for darkening are absorbed by the non-functional dye used for the coloring and are therefore unavailable to the photochromic dye used for the functional coloring.

[0007] Against this background, the object of the present invention is to provide a method which allows a substrate to be provided with a coloring in addition to a functional coloring, wherein the method to be provided is intended to enable a reproducible coloring of the substrate without impairing its functional coloring.

[0008] The above object is achieved by the embodiments of the present invention characterized in the claims.

[0009] According to the present invention, a method for providing a substrate with a coloration and a functional coloration is provided, the method according to the invention comprising the following steps (a) to (c) in this order:

[0010] (a) Providing a substrate to be provided with a coloring and a functional coloring, wherein the substrate is made of plastic glass and the substrate has a first main side and a second main side opposite the first main side with a convex shape,

[0011] (b) applying a coloring to both main sides of the substrate provided in step (a), and

[0012] (c) applying a functional dye to both main sides of the substrate provided with a dye on both main sides in step (b) by dip coating, thereby obtaining a substrate provided with a dye and a functional dye on both main sides.

[0013] The process according to the invention enables reproducible coloring of the substrate without compromising its functional coloration. This is due to the specific sequence of process steps. Since the application of the functional coloration occurs after the application of the dye, the disadvantages associated with established prior art manufacturing processes can be avoided. Advantageously, the substrate obtained with the process according to the invention is provided with both the coloration and the functional coloration on both sides, which is desirable not least for aesthetic reasons.

[0014] In the following, the method according to the invention for providing a substrate with a coloring and a functional coloring, which is shown schematically in Figure 1, is described in more detail:

[0015] In step (a) of the process according to the invention, a substrate is provided to be provided with a coloring and a functional coloring. According to the present invention, the substrate is made of plastic glass. Plastic glass has the advantage over mineral glass that it has a lower density and is therefore lighter for the same substrate size. Furthermore, plastic glass has increased break resistance compared to mineral glass. Suitable plastic materials for the production of plastic glasses are known to those skilled in the art. For example, the substrate can be made of polythiourethane, polymethyl methacrylate, polycarbonate, polyacrylate, polydiethylene glycol bisallyl carbonate, or a combination thereof, although other transparent plastic materials can also be used in principle.

[0016] The substrate has a first main side and a second main side opposite the first main side. The first main side of the substrate corresponds to the back of the future spectacle lens, which faces the wearer, while the second main side of the substrate corresponds to the front of the future spectacle lens, which faces away from the wearer. According to the present invention, the second main side of the substrate has a convex shape. With regard to the shape of the first main side of the substrate, the method according to the invention is not further restricted. For example, the first main side of the substrate can have a concave or planar shape, as described in more detail below.

[0017] If the substrate provided in step (a) is a finished part, the first main side of the substrate typically has a concave shape. A finished part is understood here to be a finished product that can be used immediately for a predetermined purpose, such as as a lens for a spectacle lens. A finished part is therefore already brought into a final geometric shape with a view to its later use. The concave shape of the first main side of the substrate therefore does not require any surface processing. The same applies to the convex shape of the second main side of the substrate.

[0018] If the substrate provided in step (a) is a half-part, the first main side of the substrate typically has a planar or concave shape. A half-part, sometimes also referred to as a "blank," is understood here to be a semi-finished product that differs from a finished product in that it cannot yet be immediately used for its intended purpose. A half-part is therefore not yet brought into a final geometric shape with a view to its later use. The planar or concave shape of the first main side of the substrate therefore requires surface processing in order to adapt the substrate to later requirements, for example, with regard to the desired optical effect, for example, with regard to the desired refractive power as resulting from an ophthalmic prescription.For this purpose, a portion of the substrate material is removed from the first main surface, forming or maintaining the concave shape. Not only in the finished part, but also in the half-part, the second main surface of the substrate already corresponds to the final optically effective surface. Thus, even in the half-part, the convex shape of the second main surface of the substrate does not require any surface processing.

[0019] If the planar or concave shape of the first main side of the substrate is subjected to surface processing, as is the case with a half-part, this takes place before step (b). Surface processing is not further restricted according to the present invention. It can be performed, for example, by milling, grinding, polishing, or a combination thereof. In principle, however, any other form of surface processing is conceivable.

[0020] In step (b) of the process according to the invention, a coloring is applied to both main sides of the substrate prepared in step (a). The coloring serves solely to impart a specific color tone to the substrate. As mentioned at the beginning, dyes are used which – apart from their absorption properties – have no functional properties whatsoever and therefore do not allow reversible switching between a dark and a light tint. Accordingly, non-functional dyes, such as those used in the process according to the invention, are non-photochromic. Various classes of non-functional dyes are described in the prior art. These are often azo dyes, cyanine dyes, anthraquinone dyes, or the like, which are frequently used in the conventional coloring of spectacle lenses.The skilled person routinely selects a suitable non-functional dye or a mixture of suitable non-functional dyes.

[0021] With regard to the application of the coloring in step (b), the method according to the invention is not further restricted. In a preferred embodiment, the application of the coloring in step (b) is carried out by immersing the substrate in a dyeing bath containing at least one non-functional dye dissolved or dispersed in a liquid medium. As a result of the immersion in the dyeing bath, the substrate is completely provided with the coloring. In particular, both main sides of the substrate are thus provided with the coloring. The dyeing bath is not subject to any particular restriction as long as it can provide the substrate with a coloring.

[0022] The dyeing bath, which can be part of a conventional dyeing system suitable for a wide variety of applications, is filled with a liquid medium. The at least one non-functional dye is dissolved or dispersed in this liquid medium. The liquid medium can be a water bath, but is not limited to this. To promote the application of the dye to the substrate, the liquid medium is typically heated to a temperature in the range of 60 to 100°C, for example to a temperature in the range of 75 to 95°C. The adjustable heating temperature of the liquid medium depends not least on its boiling point. At elevated temperatures, the absorption of the non-functional dye by the surface of the substrate is promoted. Further details regarding the dyeing process in a dyeing bath are known to those skilled in the art.

[0023] Finally, the extent of dye uptake can be controlled based on the duration of immersion. The extent of dye uptake increases with the duration of immersion. As the extent of dye uptake increases, the transmittance of the substrate, which was dyed on both main sides in step (b), decreases. The desired transmittance of the substrate, also referred to as target transmittance, can therefore be specifically adjusted in step (b), enabling reproducible dyeing of the substrate.

[0024] In step (c) of the process according to the invention, a functional dye is applied to both main sides of the substrate provided with a dye in step (b). The result is a substrate provided with a dye and a functional dye on both main sides. The functional dye serves to impart a specific functional property to the substrate. If the functional property is based on a reversible change in absorption behavior caused by an external stimulus such as UV light, the functional dye can be induced by at least one photochromic dye. Various classes of photochromic dyes are described in the prior art. These are frequently chromenes, viologens, fulgides, and fulgimides, and in particular also spiro compounds such as spirooxazines or spiropyrans, but are not limited to these.The skilled person routinely selects a suitable photochromic dye or a mixture of suitable photochromic dyes.

[0025] According to the present invention, in step (c) the functional coloration is applied by dip coating, which can be carried out in a conventional dip coating system that can be used for a variety of applications. Compared to spin coating, in which initially only one of the two main sides of the substrate is provided with a functional coloration, dip coating requires significantly less equipment. Naturally, in dip coating the substrate is completely provided with the functional coloration. In particular, both main sides of the substrate are provided with the functional coloration. If the functional coloration is caused by at least one photochromic dye, the substrate provided with a coloration on both main sides is expediently immersed in a photoresist containing the at least one photochromic dye.The photoresist forms a polymer layer on the substrate. This layer is unaffected by the underlying coloring. Therefore, the coloring does not impair the functional coloring.

[0026] Apart from steps (a) to (c), the process according to the invention can further comprise a step of applying one or more coating layers to at least one of the two main sides of the substrate obtained in step (c), which is provided with a coloring and a functional coloring on both main sides, hereinafter also referred to as step (d). If provided, step (d) is therefore carried out following steps (a) to (c), with both main sides of the substrate usually being coated. Typical coating layers include hard coatings, which serve to protect against scratches, interference-Z anti-reflective coatings, which serve to reduce reflections, and easy-care coatings, sometimes also referred to as a "topcoat." 1or "cleancoat," which serve to repel water and dirt, but are not limited thereto. Appropriate measures for applying such coatings are known to those skilled in the art. The application of a hard coating can be achieved, for example, by dip coating, using the same dip coating system as in step (c). For this purpose, the substrate, which has been provided with a coloring and a functional coloring on both main sides, is immersed in a hard coating. If a photoresist is used when applying the functional coloring in step (c), it may be necessary to remove excess photoresist residues from the edges of the substrate before coating in step (d).

[0027] According to the present invention, the substrate is provided with a coloring and a functional coloring on both main sides. The substrate, which is provided with a coloring and a functional coloring on both sides and is obtainable using the inventive method, is versatile and can be used, for example, as a lens for an eyeglass lens. The substrate is then edge-machined for fitting into an eyeglass frame. Description of the figure:

[0028] Figure 1 shows a schematic representation of the process according to the invention. Step (d), also shown in Figure 1, is optional.

[0029] List of reference symbols:

[0030] 1 substrate

[0031] 11 first main page of the substrate

[0032] 12 second main page of the substrate

[0033] 2 Coloring

[0034] 3 Functional staining

[0035] Example

[0036] The following embodiment serves to further explain the present invention, but is not limited thereto.

[0037] In accordance with the process of the invention, substrates were dyed on both sides with a coloring and a functional dyeing. Different non-functional dyes, such as anthraquinone dyes or azo dyes, were used for the coloring. However, the same photochromic dye was always used for the functional dyeing.

[0038] The substrates were half-sections made of plastic glass with a first main side, which had a planar shape, and a second main side, which had a convex shape. The first main side of the half-sections was subjected to surface processing. This was carried out by grinding, whereby a portion of the substrate material was removed from the first main side, forming a concave shape to achieve the desired optical effect. The surface-processed substrates were then immersed in a dyeing bath. This contained the respective non-functional dye for coloring in an aqueous solution. By immersing the substrates in the dyeing bath, both sides were colored. The duration of the immersion was selected so that the target transmittance was achieved. The dyeing process took place at a temperature in the range of 60 to 100°C.

[0039] The substrates, which had been colored on both sides, were then immersed in a photoresist containing the photochromic dye for the functional coloring, whereby the substrates were also colored on both sides.

[0040] A hard coating was then applied to both main surfaces of the substrates, which had been coated with the coloring and functional coloring on both sides. This was done by dipping the substrates in a hard lacquer. An interference-Z anti-reflective coating was then applied to this coating. The resulting substrates possessed all the required properties and thus represented raw, round ophthalmic lenses that could be edge-machined for fitting into an ophthalmic frame.

[0041] As can be seen from the above embodiment, the method according to the invention allows a reproducible coloring of the substrate without impairing its functional coloring.

Claims

Claims: Method for providing a substrate with a coloring and a functional coloring, comprising the following steps (a) to (c) in this order: (a) Providing a substrate to be provided with a coloring and a functional coloring, wherein the substrate is made of plastic glass and the substrate has a first main surface and a second main surface opposite the first main surface having a convex shape, (b) Applying a colorant to both main sides of the substrate provided in step (a), and (c) Applying a functional color to both main surfaces of the substrate, which was colored on both main surfaces in step (b), by dip coating, thereby obtaining a substrate colored and functionally colored on both main surfaces. A method according to claim 1, wherein the substrate provided in step (a) is made of polythiourethane, polymethyl methacrylate, polycarbonate, polyacrylate, polydiethylene glycol bisallyl carbonate, or a combination thereof. A method according to claim 1 or 2, wherein the substrate provided in step (a) is a finished part with a concave shape on the first main surface, which does not require surface treatment. A method according to claim 1 or 2, wherein the substrate provided in step (a) is a half-part with a planar or concave shape on the first main surface, which is subjected to surface treatment before step (b).Method according to claim 4, wherein the surface processing is carried out by milling, grinding, polishing or a combination thereof. A method according to any one of claims 1 to 5, wherein the application of the coloring in step (b) is carried out by immersing the substrate in a dye bath containing at least one non-functional dye dissolved or dispersed in a liquid medium. A method according to any one of claims 1 to 6, wherein the functional coloring is caused by at least one photochromic dye. A method according to claim 7, wherein in step (c) the substrate, which is provided with a coloring on both main sides, is immersed in a photoresist containing the at least one photochromic dye. A method according to any one of claims 1 to 8, further comprising the following step (d): Applying one or more coating layers to at least one of the two main sides of the substrate obtained in step (c), which is provided on both main sides with a coloring and a functional coloring. The method according to claim 9, wherein the substrate, which is provided on both main sides with a coloring and a functional coloring, is immersed in a hard lacquer to apply a hard coating.

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