DE202021004149U1 - Glasses with reduced friction properties - Google Patents

Abstract

wobei in der Formel (A) a 1 oder 2 ist, Rf einen Perfluoralkyletherrest, wenn a 1 ist, oder einen Perfluoralkylenetherrest, wenn a 2 ist, bezeichnet, X einen Rest mit mindestens einer Silylgruppe, welche mit einer oder mit mehreren hydrolysierbaren Gruppen substituiert sein kann, bezeichnet und Y einen optionalen Rest, welcher den Perfluoralkyl(en)etherrest Rf und den Rest X miteinander verknüpft, bezeichnet.

Spectacle lens, having a coating applied thereto, wherein the coating applied to the spectacle lens, starting from the surface of the spectacle lens, comprises the following layer sequence:
optionally a primer layer;
optionally a hard layer;
optionally an interference/antireflection layer; and
a functional coating,
wherein the functional coating is formed from a compound (1) comprising a perfluorinated hydrocarbon radical which has one or more ethereal oxygen atoms and further comprising at least one silyl group which can be substituted with one or more hydrolyzable groups, with the proviso that that the compound (1) contains at least two hydrolyzable groups, and wherein the compound (1) is represented by the formula (A) below:

wherein in formula (A) a is 1 or 2, Rf denotes a perfluoroalkyl ether radical when a is 1 or a perfluoroalkylene ether radical when a is 2, X denotes a radical having at least one silyl group substituted with one or more hydrolyzable groups may be, and Y denotes an optional group linking the perfluoroalkyl(ene) ether group Rf and the group X together.

Description

The present invention relates to a spectacle lens having a coating applied thereto.

Spectacle lenses which can be coated with a plurality of different layers are known in the prior art. For example, the lens can be protected from scratches by coating it with a hard coating. Reflection reduction can be achieved by coating with an interference/anti-reflection coating. Finishing with a functional coating, which is sometimes also referred to as a top coat or clean coat, ultimately serves to repel dirt and water droplets. Starting with the surface of the spectacle lens, a typical layer structure has the layer sequence hard layer, interference/anti-reflection layer and functional coating. The latter thus represents the outermost coating layer. Each of the coating layers mentioned above can consist of a single layer or of a layer system with several layers.

In order to be repellent to dirt and water droplets, the functional coating usually has both oleophobic and hydrophobic properties. A measure of this is the respective contact angle that a corresponding liquid forms on the surface of the spectacle lens. It is generally the case here that the oleophobic and hydrophobic properties are all the more pronounced the larger the contact angle of the respective liquid on the surface of the spectacle lens. Spectacle lenses coated with a functional coating can be easily cleaned of dirt and water droplets that would otherwise stick to the surface of the lens. Nevertheless, the spectacle lens has to be cleaned from time to time, for example by cleaning it with a wiping object, such as a microfiber cloth or the like. If the spectacle lens is previously brought into contact with running water, such a wiping object is also required in order to dry the spectacle lens. In the present case, cleaning is also understood to mean such drying.

In principle, sliding the wiping object over the surface of the spectacle lens requires a certain amount of effort, which also increases when the wiping speed increases. If the force applied when wiping is too low, the wiping object will stick to the lens. This can lead to the fingers slipping over the wiping object. This in turn affects the cleaning process. As a result, the surface of the lens does not feel sufficiently smooth when brushed with the wiping object.

Under ideal conditions, an optimal cleaning result can be achieved by wiping the surface of the lens once with a clean microfiber cloth, which is also known as “one wipe clean”. Nevertheless, most spectacle wearers make several alternating cleaning strokes in the width direction of the spectacle lens when cleaning the lens, i.e. alternating from left to right or right to left. In this case, a spectacle lens whose surface does not feel sufficiently smooth is perceived as particularly annoying.

The approaches known in the prior art for coating a spectacle lens with a functional coating are typically aimed at improving the oleophobic and hydrophobic properties in order to make the surface of the spectacle lens even more repellent to adhesions such as dirt and water drops. Accordingly, when it comes to coating spectacle lenses, the focus has so far been on improving the dirt and water-repellent properties of the spectacle lens and not on particularly easy wiping with little effort.

The present invention is therefore based on the object of providing a spectacle lens coated with a functional coating, whereby this should be coated in such a way that, in addition to repelling dirt and water droplets, particularly smooth wiping with little effort is possible.

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

• gegebenenfalls eine Grundierungsschicht;
• gegebenenfalls eine Hartschicht;
• gegebenenfalls eine Interferenz-/Entspiegelungsschicht; und
• eine funktionelle Beschichtung,
• wobei die funktionelle Beschichtung aus einer Verbindung (1), umfassend einen perfluorierten Kohlenwasserstoffrest, welcher ein oder mehrere etherische Sauerstoffatome aufweist, und weiter umfassend mindestens eine Silylgruppe, welche mit einer oder mit mehreren hydrolysierbaren Gruppen substituiert sein kann, gebildet ist, mit der Maßgabe, dass die Verbindung (1) mindestens zwei hydrolysierbare Gruppen enthält, und wobei die Verbindung (1) durch die nachstehende Formel (A) dargestellt ist:

In particular, a spectacle lens is provided according to the invention, having a coating applied thereto, wherein the coating applied to the spectacle lens comprises the following layer sequence, starting from the surface of the spectacle lens:

• optionally a primer layer;
• optionally a hard layer;
• optionally an interference/antireflection layer; and
• a functional coating,
• wherein the functional coating is formed from a compound (1) comprising a perfluorinated hydrocarbon radical which has one or more ethereal oxygen atoms and further comprising at least one silyl group which can be substituted with one or more hydrolyzable groups, with the proviso that that the compound (1) contains at least two hydrolyzable groups, and wherein the compound (1) is represented by the formula (A) below:

In formula (A), a is 1 or 2, Rf denotes a perfluoroalkyl ether radical when a is 1 or a perfluoroalkylene ether radical when a is 2, X denotes a radical having at least one silyl group substituted with one or more hydrolyzable groups and Y denotes an optional radical which links the perfluoroalkyl(ene)ether radical Rf and the radical X together.

The spectacle lens according to the invention, which is coated with a specific functional coating formed from compound (1), allows particularly easy wiping with little effort. In addition, the effort required increases only slightly as the wiping speed increases. The surface of the spectacle lens according to the invention feels particularly smooth when wiped, which in turn is perceived as very pleasant to the touch. It is therefore rated as very high quality. In addition, due to the oleophobic and hydrophobic properties of the functional coating formed from the compound (1), the spectacle lens according to the invention has excellent dirt and water repellency and thus overall excellent cleanability and handling properties.

• Gemäß der vorliegenden Erfindung unterliegt das Brillenglas als solches keinen besonderen Einschränkungen. In Bezug auf seine geometrische Form etwa kann das Brillenglas grundsätzlich planparallel, bikonkav, plankonkav, konvexkonkav, konkavkonvex, plankonvex oder bikonvex sein. Typischerweise ist die Vorderfläche des Brillenglases konvex geformt, während die zum Auge liegende Rückfläche konkav geformt ist. Hierbei wird die geometrische Form bei Brillengläsern mit positiver Brechkraft als konkavkonvex und bei Brillengläsern mit negativer Brechkraft als konvexkonkav bezeichnet. Was die geometrische Form des Brillenglases anbelangt, sind weiterhin noch Gleitsichtgläser zu nennen. Diese werden im Stand der Technik auch als Progressivgläser bezeichnet.

The spectacle lens according to the invention with the coating applied thereto is explained in more detail below:

• According to the present invention, the spectacle lens itself is not particularly limited. With regard to its geometric shape, for example, the spectacle lens can basically be plane-parallel, biconcave, plano-concave, convex-concave, concave-convex, plano-convex or biconvex. Typically, the front surface of the spectacle lens is convex in shape, while the back surface facing the eye is concave in shape. Here, the geometric shape is referred to as concave-convex for spectacle lenses with a positive refractive power and as convex-concave for spectacle lenses with a negative refractive power. As far as the geometric shape of the spectacle lens is concerned, progressive lenses should also be mentioned. In the prior art, these are also referred to as progressive lenses.

With regard to the base material, the spectacle lens is also not further restricted. The spectacle lens can be made of mineral glass or plastic glass. Plastic glass has the advantage over mineral glass that it is less dense and therefore lighter, which makes it more comfortable to wear. Furthermore, spectacle lenses made of plastic glass are more break-resistant. In the present case, suitable plastic materials are, for example, polythiourethane, polymethyl methacrylate, polycarbonate, polyacrylate or polydiethylene glycol bisallyl carbonate and combinations thereof, although in principle other transparent plastic materials can also be used.

The base material of the spectacle lens is selected in such a way that the spectacle lens typically has a refractive index in a range from 1.45 to 1.90, in particular in a range from 1.45 to 1.55, in a range from 1.59 to 1, 68 or in a range of 1.73 to 1.75. Spectacle lenses made of standard glass with a refractive index of approximately 1.50, of quality glass with a refractive index of approximately 1.60 or 1.67 or of premium glass with a refractive index of approximately 1.74 can thus be used.

As mentioned at the outset, a hard layer can first be applied to the spectacle lens. This makes sense in particular when the spectacle lens is made of plastic glass, since this is a comparatively soft material and thus the susceptibility of a spectacle lens made from it against scratches is higher than with mineral glass. The hard layer can have a single-layer or multi-layer structure. Various materials and methods can be used to produce the hard layer, which a person skilled in the art selects in a suitable manner. Also, a person skilled in the art selects a suitable thickness for the hard layer. If the hard layer is a hard lacquer, this can be applied to the spectacle lens by means of a dipping, spraying or spin-coating method, for example. If, on the other hand, the hard layer is an inorganic material, such as a quartz-based material, this can be applied to the spectacle lens by means of physical or chemical vapor deposition.

In order to promote the adhesion of the hard coating, the lens can be subjected to a priming treatment beforehand. For this purpose, the spectacle lens can also be provided with a base layer, also called a primer layer. In addition to the adhesive strength of the coating, the primer layer can also increase the breakage resistance of the spectacle lens. The spectacle lens can be provided with a primer layer, for example, by means of dipping, spraying or spin-coating processes.

An interference/antireflection coating can be applied to the spectacle lens with the optionally present primer layer and the optionally present hard layer. Like the hard layer, the interference/antireflection coating can also have a single-layer or multi-layer structure. A person skilled in the art is familiar with such single-layer or multi-layer interference/anti-reflection coatings, in the case of a multi-layer interference/anti-reflection coating the number of layers is fundamentally not further restricted. In the case of a multi-layered interference/antireflection layer, the layer sequence is usually selected in such a way that a layer with a low refractive index of a specific thickness is adjoined by a layer with a high refractive index of a specific thickness. In other words, it is preferred for such a structure that layers with a low refractive index and layers with a high refractive index are applied alternately. Appropriate materials and layer thicknesses for realizing such a structure are known to a person skilled in the art. The interference/anti-reflection layer can be made from a sequence of different transparent materials, including, for example, SiO ₂ , SiO, Ta ₂ O ₅ , TiO ₂ , ZrO ₂ , Al ₂ O ₃ , Nd ₂ O ₅ , Pr ₂ O ₃ , PrTiO ₃ , La ₂ O ₃ , Nb ₂ O ₅ , Y ₂ O ₃ , HfO ₂ , InSn oxide (ITO), Si ₃ N ₄ , MgO, MgF ₂ , CeO ₂ and ZnS, exist, but are not limited to these. Among these materials, some, such as SiO ₂ , have a relatively low refractive index, while still others, such as Ta ₂ O ₅ , have a relatively high refractive index. The respective layers of the interference/antireflection layer can also be applied by means of physical or chemical vapor deposition. Exemplary physical vapor deposition methods include, but are not limited to, electron beam crucible evaporation, resistance boat evaporation, and plasma assist during evaporation. The spectacle lens can be heated when the interference/anti-reflection coating is applied.

According to the present invention, a functional coating is applied to the spectacle lens with the optionally present primer layer, the optionally present hard layer and the optionally present interference/antireflection layer. This has both oleophobic and hydrophobic properties, making it possible to repel both dirt and water droplets on the surface of the lens. According to the invention, the functional coating is formed from a compound (1) comprising a perfluorinated hydrocarbon radical which has one or more ethereal oxygen atoms and further comprising at least one silyl group which can be substituted by one or more hydrolyzable groups, with the proviso that that the compound (1) contains at least two hydrolyzable groups.

The presence of at least two hydrolyzable groups can in principle lead to a two- or three-dimensional linkage of the compound (1) to one another and to the surface of the spectacle lens, a primer layer optionally applied thereon, a hard layer optionally applied thereon or an interference/interference layer optionally applied thereon. anti-reflective coating come. A two-dimensional linkage requires a compound (1) having two hydrolyzable groups, while a three-dimensional linkage requires a compound (1) having at least three hydrolyzable groups. The linkage of the compound (1) is carried out by hydrolysis reaction of the hydrolyzable groups in the presence of water, which is present in trace amounts when the functional coating is applied, followed by a condensation reaction, finally forming a siloxane bond. However, the compound (1) can also be present as such in the functional coating, ie without having entered into a hydrolysis reaction. Accordingly, hydrolyzable groups can still be present in the functional coating of the spectacle lens according to the invention. In other In other words, the functional coating of the spectacle lens according to the invention is formed from compound (1) or derived from it.

It is preferred that the compound (1) contains at least three hydrolyzable groups since, as mentioned above, this can in principle lead to a three-dimensional linkage of the compound (1). Basically, a three-dimensional connection increases the mechanical stability of the functional coating and thus also its abrasion resistance and longevity. With regard to an upper limit, the number of hydrolyzable groups according to the present invention is not further restricted.

The hydrolyzable groups may each independently be selected from, for example, an alkoxy group having from 1 to 10 carbon atoms, such as a methoxy group, an ethoxy group, a propoxy group or a butoxy group, an alkoxyalkoxy group having from 2 to 10 carbon atoms, such as a methoxymethoxy group or a methoxyethoxy group, an alkenyloxy group having from 2 to 10 carbon atoms, e.g. isopropenoxy, an acyloxy group having 1 to 10 carbon atoms, e.g. acetyloxy, an amino group or a halogen atom, e.g. chlorine, bromine or iodine. Among these hydrolyzable groups, a methoxy group, an ethoxy group, an isopropenoxy group and a chlorine atom are preferred.

For example, when the hydrolyzable group is a halogen atom, the hydrolysis reaction liberates the respective hydrogen halide. In the case of an alkoxy group, the respective alcohol is released. The hydrolyzable group is thus released in its protonated form.

In the compound (1), all hydrolyzable groups can be identical. For example, each of the hydrolyzable groups can be a methoxy group or an ethoxy group. Also, in the compound (1), the silyl groups may be fully substituted with hydrolyzable groups such that the compound (1) has, for example, but not limited to, trimethoxysilyl groups or triethoxysilyl groups. In the absence or incomplete substitution with hydrolyzable groups, the silyl groups typically still contain alkyl or alkenyl radicals having from 1 to 3 carbon atoms, such as, but not limited to, methyl, ethyl, propyl, or vinyl.

As for the perfluorinated hydrocarbon group, the compound (1) is not particularly limited as long as the perfluorinated hydrocarbon group has one or more ethereal oxygen atoms. In the present case, an ethereal oxygen atom is understood as meaning an oxygen atom which forms an ether functionality within the perfluorinated hydrocarbon radical. With regard to an upper limit, the number of ethereal oxygen atoms according to the present invention is not further restricted.

The number of carbon atoms in the perfluorinated hydrocarbon radical can be from 2 to 100, for example from 2 to 50, from 5 to 50, from 5 to 25 or from 10 to 25, but is not limited thereto. The perfluorinated hydrocarbon radical is typically saturated and thus contains no carbon-carbon multiple bonds. Also, the perfluorinated hydrocarbon radical is typically aliphatic and thus contains no aromatic moieties. The perfluorinated hydrocarbon radical may be branched or unbranched, with an unbranched structure being preferred. It is also preferred that the perfluorinated hydrocarbon residue is non-cyclic.

The perfluorinated hydrocarbon radical, which has one or more ethereal oxygen atoms, can include, for example, the structural unit -(CF ₂ ) _x -O-(CF ₂ ) _y -, where the indices x and y each denote the number of difluoromethylene units and thus also the Denote number of carbon atoms. Attached to either or both of the outer difluoromethylene units thereof may be a silyl group optionally substituted with one or more hydrolyzable groups. If only one of the two outer difluoromethylene units has a silyl group attached, a fluorine atom is attached to the other of the two outer difluoromethylene units. In addition, a fluorine atom of the two outer or inner difluoromethylene units can also be replaced by a silyl group, optionally substituted with one or more hydrolyzable groups. Furthermore, between a difluoromethylene unit and a silyl group there may be another perfluorinated hydrocarbon residue of the above structural unit, which links the difluoromethylene unit and the silyl group together. Further silyl groups, optionally substituted with one or more hydrolyzable groups, can be bonded to such a perfluorinated hydrocarbon radical.

The compound (1) can also comprise further structural units, provided that the compound (1) comprises a perfluorinated hydrocarbon radical which has one or more ethereal oxygen atoms and further comprises at least one silyl group which can be substituted with one or more hydrolyzable groups, with the proviso that the compound (1) contains at least two hydrolyzable groups.

The proviso that compound (1) contains at least two hydrolyzable groups applies to formula (A) in that when the radical X in formula (A) contains only one silyl group substituted with a single hydrolyzable group, a must then necessarily be 2.

For the perfluoroalkyl(ene) ether radical Rf in the formula (A), the statements made in general for the compound (1) with regard to the perfluorinated hydrocarbon radical apply, correspondingly with the restriction that the perfluoroalkyl(ene) ether radical Rf is not a carbon -Contains multiple carbon bonds and no aromatic units. Otherwise, the perfluoroalkyl(ene) ether radical Rf is not subject to any further restrictions.

The radical X in formula (A) contains at least one silyl group, where each silyl group can be substituted with one or more hydrolyzable groups. The radical X contains, for example, 2 to 18, preferably 2 to 9, hydrolyzable groups. When more than three hydrolyzable groups are present, there is necessarily more than one silyl group in the X moiety. Otherwise, with regard to the silyl groups and the hydrolyzable groups, the above general statements in connection with the compound (1) apply accordingly.

The optional group Y is a divalent group and links the perfluoroalkyl(ene) ether group Rf and the group X together. The optional radical Y, if present, generally has no hydrolyzable groups. The optional group Y can be an unsubstituted or substituted hydrocarbyl group. The optional radical Y can contain one or more structures selected from the group consisting of -NR(CO)-, -O(CO)-, -O- and -SiR ₂ -, where R contains an alkyl or alkenyl radical R1 represents 1 to 3 carbon atoms such as, but not limited to, methyl, ethyl, propyl or vinyl. For example, the optional group Y can be a hydrocarbyl group having a total of from 2 to 12 carbon atoms, which hydrocarbyl group can contain one or more of the structures mentioned above.

Examples of the compound (1) which are in accordance with the formula (A) include trimethoxysilane, dimethoxysilane, triethoxysilane, triisopropenoxysilane, trichlorosilane and triaminosilane, each of these silanes comprising a perfluoroalkyl ether group. In particular, the silane can be trimethoxysilane comprising a perfluoroalkyl ether radical.

The functional coating is not necessarily formed from only a single compound (1). It can also be formed from different compounds (1). A compound (2) which differs from compound (1) only in that compound (2) contains only a single hydrolyzable group can also be involved in the formation of the functional coating. This makes it possible to saturate the end points of the two- or three-dimensional linkage, since the compound (2) cannot form a two- or three-dimensional linkage due to the presence of only one hydrolyzable group.

The functional coating can be applied to the spectacle lens with the optionally present primer layer, the optionally present hard layer and the optionally present interference/antireflection layer by means of suitable vapor deposition techniques, as described in more detail below in connection with the production method.

In terms of thickness, the functional coating is not further restricted. The thickness of the functional coating can be in a range from 1 nm to 1000 nm. The thickness of the functional coating is preferably in a range from 1 nm to 100 nm and even more preferably in a range from 1 nm to 20 nm. A value of about 10 nm for the thickness of the functional coating is mentioned here as an example. The thickness of the functional coating can be adjusted, for example, by the duration of the vaporization and the vapor deposition rate.

In principle, the above layers can be applied to one side or both sides of the spectacle lens, with preference being given to applying at least the functional coating to the front and rear surfaces of the spectacle lens on both sides.

• Im Rahmen der vorliegenden Erfindung beschreibt die Bewegung zur messtechnischen Bestimmung des dynamischen Reibungskoeffizienten einen Kreis um die Mitte des Brillenglases. Die Geschwindigkeit, auf die sich der dynamische Reibungskoeffizient bezieht, ist tangential zum beschriebenen Kreis sowie tangential zur Oberfläche des Brillenglases. Sie wird daher gelegentlich auch als tangentiale Geschwindigkeit bezeichnet. Als praxisrelevant für die Geschwindigkeit ist hierbei ein Bereich von 0,005 m/s bis 0,4 m/s anzusehen, da das Putzen eines Brillenglases typischerweise mit einer Geschwindigkeit in eben diesem Geschwindigkeitsbereich erfolgt. Wie durch Messungen festgestellt werden konnte, liegt die maximale Geschwindigkeit der Wischbewegung typischerweise bei einem Wert von 0,2 m/s.

Due to the specific functional coating, which is formed from compound (1), as described above, the surface of the spectacle lens according to the invention has a particularly low dynamic coefficient of friction. This can be understood as a measure of the perceived smoothness with which the surface of the spectacle lens is perceived. The dynamic coefficient of friction refers here to the frictional force which has to be overcome in order to carry out a movement of the wiping object on the surface of the spectacle lens, such as when cleaning the spectacle lens with a microfiber cloth or the like. In principle, the dynamic coefficient of friction depends on the speed of the wiping movement. It is therefore sometimes also referred to as the speed-dependent dynamic coefficient of friction. Basically, this means that the dynamic coefficient of friction would have to be determined continuously up to the maximum speed of the wiping movement in order to accurately depict the perceived smoothness metrologically. However, as the inventors found out, the metrological representation of the perceived smoothness can be greatly simplified, as explained below in connection with the determination of the dynamic coefficient of friction:

• Within the scope of the present invention, the movement for the metrological determination of the dynamic coefficient of friction describes a circle around the center of the spectacle lens. The speed to which the dynamic coefficient of friction refers is tangential to the described circle and tangential to the surface of the lens. It is therefore sometimes also referred to as tangential speed. A range of 0.005 m/s to 0.4 m/s is to be regarded as relevant for the speed in practice, since the cleaning of a spectacle lens typically takes place at a speed in precisely this speed range. As could be determined by measurements, the maximum speed of the wiping movement is typically at a value of 0.2 m/s.

When determining the dynamic coefficient of friction, a “Savina MX” type microfiber cloth, manufactured by “kbSeiren”, Osaka, Japan, with the following properties is used here: • Fiber type: ultra-fine microfibre "BelimaX" • Composition: 70% polyester, 30% nylon • Thickness: 0.32mm • area based size: 165 ^gsm • Length-related number of longitudinal threads: 78/2.54 cm • Length-related number of warp threads: 81/2.54 cm

The microfiber cloth is wiped in a rotating motion around the center of the lens with the functional coating applied to it. When wiping with the microfiber cloth, it must be ensured that no rubbing action has been carried out on the surface of the spectacle lens beforehand, which could change its properties. The microfiber cloth is pressed onto the surface of the lens to be measured by an elastic stamp with a ring-shaped contact surface and is approximately 8380 N/m ² . With an inner radius of 17.5 mm and an outer radius of 20.5 mm for the ring-shaped contact surface, this corresponds to a pressing force of 3 N. Viewed in cross section, the elastic stamp has a rectangular shape with a height of 3 mm. The elastic stamp is made of silicone and has a Shore A hardness of 40.

In the area of the ring-shaped contact surface of the elastic stamp, the microfiber cloth moves relative to the surface of the spectacle lens. In order to take account of the speed dependency of the dynamic coefficient of friction, the dynamic coefficient of friction is expediently determined in the aforementioned speed range of 0.005 m/s to 0.4 m/s, the speed, as mentioned above, meaning the tangential speed. Starting from an initial value, the speed is gradually increased.

During the rotating movement of the microfiber cloth, the torque is determined using a rheometer. This is about the effective radius of the elastic's annular bearing surface linked to the frictional force that the microfiber cloth has to overcome for a uniform movement relative to the surface of the lens as follows: $$\text{torque}=\text{friction force}\times \text{effective radius}$$

The effective radius can be approximated using the mean radius. This corresponds to the mean radius of the annular contact surface of the elastic stamp and can be calculated as follows: $$\text{medium radius}=\frac{\text{outer radius}+\text{inner radius}}{2}$$

The dynamic coefficient of friction, abbreviated as µ _d , is in turn related to the torque via the effective radius and the contact force as follows: $${\mathrm{\mu }}_{\text{i.e}}=\frac{\text{torque}}{\text{effective radius}\times \text{pressure force}}=\frac{\text{friction force}}{\text{pressure force}}$$

For each speed v there is an individual torque(v), caused by an individual frictional force(v), and thus also an individual dynamic friction coefficient(v), abbreviated as µ _d (v): $${\mathrm{\mu }}_{\text{i.e}}\left(\text{v}\right)=\frac{\text{torque}\left(\text{v}\right)}{\text{effective radius}\times \text{pressure force}}=\frac{\text{friction force}\left(\text{v}\right)}{\text{pressure force}}$$

In order to depict the perceived smoothness metrologically, it is crucial how the speed v is distributed over the path s over the surface of the lens during the time t during a cleaning stroke. Studies using a camera with a high frame rate show that during a cleaning stroke, the speed distribution along the path covered by the wiping object can be very well approximated with a harmonic oscillation, with the wiping object coming to a standstill at the reversal points. Due to the symmetry of the wiping movement as a harmonic oscillation, it is sufficient that the speed distribution is only considered for a 1/4 cleaning stroke, ie from the center of the lens with position s = 0 at time t = 0, where the wiping movement reaches its maximum speed v _max reached, to the reversal point with the position s = s _max at time t = T/4, where the wiping movement comes to a standstill. T denotes the duration of an entire cleaning stroke, corresponding to a complete oscillation period. The following relationship results for the path of a 1/4 cleaning stroke as a function of time: $$\text{s}\left(\text{t}\right)={\text{s}}_{\text{Max}}\times \text{sin}\left(2\mathrm{\pi /}\text{T}\times \text{t}\right)={\text{s}}_{\text{Max}}=\text{sin}\left(\mathrm{\omega }\times \text{t}\right)\text{with t}\in \left[0;\text{T/4}\right]$$

Solved for time, the result is the following expression: $$\text{t}\left(\text{s}\right)1/\mathrm{\omega }\times \text{arcsin}\left(\text{s}/{\text{s}}_{\text{Max}}\right)\text{with s}\in \left[0;{\text{s}}_{\text{Max}}\right]$$

If you derive the distance according to time, you get the speed as a function of time: $$\text{v}\left(\text{t}\right)=\text{ds}\left(\text{t}\right)/\text{German}={\text{s}}_{\text{Max}}\times \text{cos}\left(\mathrm{\omega }\times \text{t}\right)\times \mathrm{\omega }={\text{v}}_{\text{Max}}\times \text{cos}\left(\mathrm{\omega }\times \text{t}\right)$$

Finally, replacing time with the above expression, we get velocity as a function of displacement: $$\text{v}\left(\text{s}\right)={\text{v}}_{\text{Max}}\times \text{cos}\left(\text{arcsin}\left(\text{s}/{\text{s}}_{\text{Max}}\right)\right)={\text{v}}_{\text{Max}}\times \sqrt{1-{\left(\text{s}/{\text{s}}_{\text{Max}}\right)}^2}$$

Velocity as a function of distance is in 1 illustrated for a 1/4 stroke of brushing. The curve that describes the speed can be divided into three sections. These can in turn be represented as bars whose area corresponds to the area under the associated curve section. As can be seen from the illustration, 50% of the distance is covered at an average speed of 95% of the maximum speed. Another 35% of the way is covered at an average speed of 72% of the maximum speed. The remaining 15% of the way is covered at an average speed of 35% of the maximum speed. Based on the weighting of the three velocities along the path (50% of the path with 95% v _max , 35% of the path with 72% v _max and 15% of the path with 35% v _max ) an appropriately weighted average dynamic friction coefficient can be specified . The weighted mean dynamic coefficient of friction, abbreviated as µ̅ _d , which is a measure of the perceived smoothness, is calculated as follows: $${\overline{\mu }}_{\text{i.e}}=0.50\times {\mathrm{\mu }}_{\text{i.e}}\left(95\%{\text{v}}_{\text{Max}}\right)+0.35\times {\mathrm{\mu }}_{\text{i.e}}\left(72\%{\text{v}}_{\text{Max}}\right)+0.15\times {\mathrm{\mu }}_{\text{i.e}}\left(35\%{\text{v}}_{\text{Max}}\right)$$

If a value of 0.2 m/s is used for v _max , which is typical for the maximum speed of the wiping movement, the weighted mean dynamic coefficient of friction is obtained as follows: $${\overline{\mu }}_{\text{i.e}}=0.50\times {\mathrm{\mu }}_{\text{i.e}}\left(0.20\text{m}/\text{s}\right)+0.35\times {\mathrm{\mu }}_{\text{i.e}}\left(0.15\text{m}/\text{s}\right)+0.15\times {\mathrm{\mu }}_{\text{i.e}}\left(0.07\text{m}/\text{s}\right)$$

The weighted mean dynamic coefficient of friction is also referred to as the haptic smoothness coefficient HGK because it is a measure of the perceived smoothness. The following applies accordingly: $$\text{HGK}=0.50\times {\mathrm{\mu }}_{\text{i.e}}\left(0.20\text{m}/\text{s}\right)+0.35\times {\mathrm{\mu }}_{\text{i.e}}\left(0.15\text{m}/\text{s}\right)+0.15\times {\mathrm{\mu }}_{\text{i.e}}\left(0.07\text{m}/\text{s}\right)$$

The smaller the haptic smoothness coefficient HGK, the greater the perceived smoothness of the surface of the lens. In terms of measurement technology, the haptic smoothness coefficient therefore corresponds to the weighted average dynamic coefficient of friction, which is determined under special parameters, for example in relation to the microfiber cloth used and the measurement geometry, as explained above. Surprisingly, the determination of the dynamic coefficient of friction at three speeds, namely at 0.20 m/s, 0.15 m/s and 0.07 m/s, is already sufficient to metrologically depict the perceived smoothness.

The spectacle lens according to the invention, which is coated with a specific functional coating formed from compound (1), has a haptic smoothness coefficient HGK of at most 0.28, preferably at most 0.25.

With the haptic smoothness coefficient HGK, the perceived smoothness can be measured. The smoothness, which can be sensed with a finger, can be measured even better if the acceleration phase near the reversal point is included. For this purpose, a dynamic coefficient of friction, which is determined at a comparatively low speed, is also taken into account. A very good comparability between empirical tests on smoothness and the description of smoothness by means of friction curves is achieved by determining the dynamic coefficient of friction at a speed of 0.01 m/s, which is close to standstill, and multiplying it by a weighting factor of 3 added to the haptic smoothness coefficient HGK. The haptic smoothness coefficient R_HGK obtained in this way is then as follows: $$\text{R\_HGK}=\text{HGK}+\text{3}\times {\mathrm{\mu }}_{\text{i.e}}\left(0.01\text{m}/\text{s}\right)$$

The spectacle lens according to the invention, which is coated with a specific functional coating formed from compound (1), has a haptic smoothness coefficient R_HGK of at most 0.85, preferably at most 0.80.

The measurement method described above for determining the two haptic smoothness coefficients HGK and R_HGK is not limited to the functional coating. In principle, it can be applied to any type of coated or uncoated (spectacle lens) surface. With the help of the two haptic smoothness coefficients HGK and R_HGK, for example, different surface coatings can be distinguished and their quality can be objectively evaluated. In this way, limit values for different quality levels can be defined.

• Bereitstellen eines Brillenglases; und
• Aufbringen einer Beschichtung auf das Brillenglas, wobei die auf das Brillenglas aufgebrachte Beschichtung ausgehend von der Oberfläche des Brillenglases die nachstehende Schichtfolge umfasst:
  • gegebenenfalls eine Grundierungsschicht;
  • gegebenenfalls eine Hartschicht;
  • gegebenenfalls eine Interferenz-/Entspiegelungsschicht; und
  • eine funktionelle Beschichtung,
  • wobei die funktionelle Beschichtung aus der vorstehend beschriebenen Verbindung (1) gebildet wird.

A method for producing the spectacle lens according to the invention is also provided within the scope of the present invention. The manufacturing process includes the following steps:

• providing a spectacle lens; and
• Application of a coating to the spectacle lens, the coating applied to the spectacle lens comprising the following layer sequence starting from the surface of the spectacle lens:
  • optionally a primer layer;
  • optionally a hard layer;
  • optionally an interference/antireflection layer; and
  • a functional coating,
  • wherein the functional coating is formed from compound (1) described above.

• Im ersten Schritt wird zunächst ein Brillenglas bereitgestellt. Wie bereits vorstehend näher ausgeführt, unterliegt das Brillenglas als solches keinen besonderen Einschränkungen. Die vorstehenden Ausführungen, wie sie diesbezüglich im Zusammenhang mit dem erfindungsgemäßen Brillenglas getroffen worden sind, gelten für das Herstellungsverfahren entsprechend.

The manufacturing process with which the spectacle lens according to the invention can be obtained is explained in more detail below:

• In the first step, a spectacle lens is provided. As already explained in more detail above, the spectacle lens as such is not subject to any particular restrictions. The above statements, as they have been made in this regard in connection with the spectacle lens according to the invention, apply accordingly to the manufacturing process.

In the subsequent step, a coating is applied to the spectacle lens, the coating optionally comprising a hard layer, optionally an interference/antireflection coating and a functional coating. As mentioned above, the hard layer and the interference/antireflection layer, if provided, can be applied by means of immersion, spraying or spin coating processes or by means of physical or chemical vapor deposition.

In addition, the lens may be subjected to a primer treatment in advance or provided with a primer layer. Here, too, the above statements, as they have been made in this regard for the spectacle lens according to the invention, apply accordingly.

In the next step, the functional coating is applied to the spectacle lens with the optionally present primer layer, the optionally present hard layer and the optionally present interference/antireflection layer. The functional coating can be applied using suitable vapor deposition techniques, in which case the surface to be coated can be subjected to a plasma treatment beforehand if required. Without being limited to this, the functional coating can be applied by evaporation in a vacuum chamber using a source containing compound (1). Here, the compound (1) serving as the starting material is vaporized, optionally together with another compound, for example the compound (2). The resulting vapor moves in the direction of the lens and is deposited on the surface of the lens by condensing to form the functional coating. Analogously, one speaks of a vapor deposition of the compound (1). For the sake of simplicity, only compound (1) is referred to here, but this is not intended to exclude the presence of another compound, such as compound (2).

Vapor deposition is a high-vacuum-based coating technique and is one of the physical vapor deposition processes. Typical process pressures range from 10 ^-7 to 10 ^-4 mbar. The starting material to be evaporated is heated to temperatures close to the boiling point. The presence of water in the vacuum chamber, which is present in small amounts during coating or afterwards, can lead to a hydrolysis reaction of the hydrolyzable groups, followed by a condensation reaction, which in principle leads to the formation of a two- or three-dimensional linkage of the vapor-deposited Connection (1) can come.

The source containing compound (1) may be a tablet or pill containing compound (1) in bound form. Tablets that can be used here can be formed, for example, from a ceramic body which has a high surface-to-volume ratio. Pills that can be used here can be formed, for example, from copper crucibles filled with steel wool. The ceramic body or the steel wool is impregnated with the starting material to be evaporated. Corresponding tablets or pills are commercially available.

The temperature during the vaporization is chosen so that, on the one hand, there is sufficient release of the starting material to be vaporized, but, on the other hand, it does not decompose. The evaporation typically takes place at an evaporation rate in a range from 0.05 nm/s to 3 nm/s, with a range from 0.1 nm/s to 1 nm/s being preferred for the maximum evaporation rate and a range from 0. 25 nm/s to 0.45 nm/s is even more preferred. The evaporation rate depends, among other things, on the evaporation temperature. Together with the duration of the evaporation, this allows the thickness of the functional coating to be applied to the spectacle lens to be adjusted.

The evaporation can take place, for example, by means of electron beams, arcs or lasers. In a preferred embodiment, the evaporation takes place with the aid of a thermal evaporator, for example with the aid of a resistance evaporator. The necessary input of energy occurs here by heating a material container. This can contain the tablet or pill containing compound (1) in bound form. The material container can be a boat made of molybdenum, tungsten or tantalum, but also a boat made of ceramic materials. Typically, the boat current is in a range of 0.1 amps to 10 amps, with a range of 1.0 amps to 7.0 amps being preferred, and a range of 3.0 amps to 6.0 amps being more preferred. The thermal evaporator is operated with an AC voltage of 230 V. The theoretical power consumption of the thermal evaporator can be calculated as follows: $$\text{theoretical power consumption}=\sqrt{2}\times 230\text{V}\times \text{boat current}$$

The functional coating obtained by evaporation does not require any special post-processing. The spectacle lens obtained with the described production method with the coating applied thereto can thus be used directly.

The present invention makes it possible to provide a spectacle lens with reduced friction properties. This is achieved by a specific functional coating formed from compound (1) as described above. Due to the oleophobic and hydrophobic properties of the functional coating, the spectacle lens according to the invention, which can be obtained using the production method described, also has excellent dirt and water repellency and therefore overall excellent cleanability and handling.

character list

• 1 shows a graphic representation of the relationship between speed and distance in the wiping movement over a spectacle lens for a 1/4 cleaning stroke. Compared to the curve on the left side, the curve on the right side has three additional bars whose area corresponds to the area under the associated curve section.
• 2 shows the dynamic coefficient of friction as a function of the wiping speed for the coated plastic spectacle lenses from Examples 1 and 2 and from the comparative example. The curves are obtained by determining the dynamic coefficients of friction at speeds of 0.0002 m/s, 0.002 m/s, 0.01 m/s, 0.03 m/s, 0.07 m/s, 0.15 m/s , 0.20 m/s and 0.40 m/s and subsequent interpolation using the dynamic coefficients of friction determined at these speeds. The points relevant for the calculation (0.01 m/s, 0.07 m/s, 0.15 m/s and 0.20 m/s) are marked.

examples

The examples below serve to further illustrate the present invention, but are not limited thereto.

example 1

A circular plastic spectacle lens with the following properties served as the substrate for the coating: • Diameter: 60mm • Refractive index: 1.60 • Refractive power (spherical power): -2.25 dpt

A hard coating was first applied to the lens using a dipping process. An interference/anti-reflection coating was applied to this in turn using an ion-assisted physical vapor deposition process. After the last layer of the interference/anti-reflection coating was applied, the surface was subjected to a plasma treatment before the functional coating was vapor-deposited on it. For this purpose, a "Surfclear 100M" type pill containing compound (1) was heated in a vacuum chamber by a resistance evaporator with a boat current of 5.4 A. In this case, a functional coating formed from the compound (1) was used a thickness of 9 nm on the interference/antireflection layer. The maximum evaporation rate was 0.45 nm/s with a coating time of 52 seconds. After applying the functional coating, the coating process was terminated and the vacuum chamber was vented.

After the coating, the spectacle lens was not subjected to any further treatment, in particular it was not subjected to any rubbing action that goes beyond the usual cleaning by wiping.

To measure the dynamic coefficient of friction, the spectacle lens coated in this way was first fixed in the center of the lower support of the measuring device using a holder in a "Haake Mars iQ Air" rheometer, so that the functional coating, which was applied to the convex side of the spectacle lens, was in direction of the rotor of the measuring device. The center of the lens came to lie exactly under the center of the rotor. A microfiber cloth of the type "Savina MX" manufactured by "kbSeiren", Osaka, Japan, with dimensions of 45 mm × 45 mm was then placed on the surface of the lens. The rotor of the measuring device was designed in such a way that at its lower end there was a circular plate on which a silicone ring with an inner radius of 17.5 mm, an outer radius of 20.5 mm and a height of 3 mm was attached in the middle. The silicone ring had a Shore A hardness of 40.

To measure the dynamic coefficient of friction, the rotor was lowered onto the convex side of the lens. With the help of the silicone ring of the rotor, the microfiber cloth was pressed vertically onto the surface of the spectacle lens with a pressure force of 3 N. By rotating the rotor, the microfiber cloth was moved uniformly relative to the surface of the lens for a specified period of time, which corresponded to four revolutions of the microfiber cloth on the surface of the lens, with a speed of 0.01 m/s tangential to the outer radius of the silicone ring . At the same time, the torque required to move the microfiber cloth relative to the surface of the spectacle lens was determined by the measuring device. From this, the dynamic coefficient of friction for a speed of 0.01 m/s could finally be determined. The dynamic coefficient of friction for speeds of 0.07 m/s, 0.15 m/s and 0.20 m/s was determined in the same way. The number of revolutions was adjusted to the respective speed, taking into account an acceleration phase to achieve a uniform speed, and was between four and eight revolutions.

The dynamic coefficients of friction determined in this way resulted in an HGK of 0.249 and an R_HGK of 0.568.

example 2

A plastic spectacle lens of the same construction was coated in a manner similar to example 1, the coating parameters being selected as follows: • Boat current: 5.7A • Thickness: 9nm • maximum evaporation rate: 0.31nm/s • Coating time: 60 seconds

After coating, the dynamic coefficients of friction were measured at speeds of 0.01 m/s, 0.07 m/s, 0.15 m/s and 0.20 m/s, as described in connection with example 1.

The dynamic coefficients of friction determined in this way resulted in an HGK of 0.276 and an R_HGK of 0.678.

comparative example

In the comparative example, a commercially available spectacle lens, which was structurally identical to the plastic spectacle lenses from example 1 and example 2 in terms of its substrate, was used.

Here too, the dynamic coefficients of friction were measured at speeds of 0.01 m/s, 0.07 m/s, 0.15 m/s and 0.20 m/s, as described in connection with Example 1.

The dynamic coefficients of friction determined in this way resulted in an HGK of 0.473 and an R_HGK of 1.77.

summary

How himself 2 can be seen, the speed-dependent dynamic coefficient of friction in the case of the coated plastic lenses from Examples 1 and 2 is comparatively low. Only a slight increase in the dynamic coefficient of friction can be observed with increasing tangential speed. The spectacle lens according to the invention thus allows particularly easy wiping with little effort. In contrast, in the comparative example, where a spectacle lens not according to the invention was used, the dynamic coefficient of friction is significantly increased.

Claims (7)

Spectacle lens, having a coating applied thereto, wherein the coating applied to the spectacle lens comprises the following layer sequence starting from the surface of the spectacle lens: optionally a primer layer; optionally a hard layer; optionally an interference/antireflection layer; and a functional coating, wherein the functional coating is formed from a compound (1) comprising a perfluorinated hydrocarbon residue having one or more ethereal oxygen atoms and further comprising at least one silyl group which may be substituted with one or more hydrolyzable groups , provided that the compound (1) contains at least two hydrolyzable groups, and wherein the compound (1) is represented by the formula (A) below:

wherein in formula (A) a is 1 or 2, Rf denotes a perfluoroalkyl ether radical when a is 1 or a perfluoroalkylene ether radical when a is 2, X denotes a radical having at least one silyl group substituted with one or more hydrolyzable groups may be, and Y denotes an optional group linking the perfluoroalkyl(ene) ether group Rf and the group X together. glasses after claim 1 , wherein the hydrolyzable groups are each independently selected from the group consisting of an alkoxy group having 1 to 10 carbon atoms, an alkoxyalkoxy group having 2 to 10 carbon atoms, an alkenyloxy group having 2 to 10 carbon atoms, an acyloxy group having 1 to 10 carbon atoms, an amino group and a halogen atom, are selected. glasses after claim 2 wherein the hydrolyzable groups are each independently selected from the group consisting of a methoxy group, an ethoxy group, an isopropenoxy group and a chlorine atom. Spectacle lens according to one of the Claims 1 until 3 wherein the compound (1) represented by the formula (A) is trimethoxysilane comprising a perfluoroalkyl ether group. Spectacle lens according to one of the Claims 1 until 4 , wherein the thickness of the functional coating is in a range from 1 nm to 100 nm. Spectacle lens according to one of the Claims 1 until 5 , wherein the haptic smoothness coefficient HGK in relation to a microfiber cloth is at most 0.28, preferably at most 0.25. Spectacle lens according to one of the Claims 1 until 6 , wherein the haptic smoothness coefficient R_HGK in relation to a microfiber cloth is at most 0.85, preferably at most 0.80.

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