Patent Application
20150360247
The invention relates to machines for coating an optical article such as an ophthalmic lens, and in particular spectacle lenses preferably mounted on a spectacle frame, with a predetermined coating composition such as an anti-soiling coating composition or an anti-fogging coating composition or an adhesion coating composition.
The invention further relates to a method for using such a machine.
It is well known that lenses, and in particular spectacle lenses, comprise an ophthalmic substrate having geometrical features adapted to the wearer.
The ophthalmic substrate requires the adding of coatings, for instance an anti-abrasive coating to increase the abrasion resistance of the lens, an anti-reflective coating to decrease the reflection of light and an anti-soiling coating or an anti-fogging coating applied over the anti-reflective coating. The anti-soiling coating provides an outer coating that can be more resistant to contamination for instance by organic impurities and more easily cleaned than the anti-reflective coating whereas the anti-fogging coating provides an outer coating that can prevent any fog formation in very damp environments or during quick temperature changes.
The wearer of the lens can wish to replace such an anti-soiling topcoat or an anti-fogging topcoat because the effects of said respective topcoat can decrease over time or might be misfit to a new environment.
One known method to remove the first anti-soiling coating and replace it by a second anti-soiling coating is described in US patent application US 2005/0008784, in which a low pressure plasma treatment is carried out to remove the first anti-soiling coating initially coated on the lens. Next, the second anti-soiling coating (the new one) is coated on the lens for instance by wiping with a woven or non-woven fabric, spraying, casting, rolling or immersing the lens. Thus, the first anti-soiling coating is removed and replaced by the second anti-soiling coating.
Such a method is also known from the International patent application WO 2004/111691 in which an activation treatment of technical species at about atmospheric pressure is carried out, in particular a corona discharge treatment or a plasma treatment, for removing an initial outermost coating layer of a coated optical lens. Next, a final coating, in particular an anti-soiling coating, is deposited on the lens by vacuum, dip, spin, spray or stamping coating. Thus, the initial outermost coating of the lens is removed and replaced by an anti-soiling coating.
The invention is thus directed to a machine for coating an optical article with a predetermined coating composition, which machine is simple to implement, compact and economic.
The invention accordingly provides a machine for coating an optical article with a predetermined coating composition, comprising:
said control unit being further configured to cause the vacuum pump to suck gases from said vacuum chamber to bring said vacuum chamber to a predetermined required pressure for said vacuum nebulization treatment; and
said control unit and said nebulizer being further configured to nebulize said predetermined coating composition which is liquid into a mist of aerosol droplets and to direct said droplets towards at least a surface of said optical article.
The vacuum nebulization treatment, also called vacuum spraying treatment, of the machine according to the invention ensures a wet-coating deposition of a thin coating in a controlled manner (due to the control unit) and in a clean environment (because the vacuum pump causes to suck gases from the vacuum chamber before the vacuum spraying treatment), therefore no floating particle may be trapped by the liquid droplets.
Thanks to the machine according to the invention, the liquid coating composition may be, prior to the deposition process, at atmospheric pressure or close to atmospheric pressure, before being nebulized in the vacuum chamber.
A vacuum pump is used to obtain the vacuum in the chamber. The vacuum pump which is connected (a flow connection causing the pump to suck) to the vacuum chamber before the carrying out of the vacuum nebulization treatment so that the quality of the vacuum spraying treatment is increased. The vacuum pump can be connected or disconnected during the vacuum nebulization treatment.
We further already known from a patent application of the Applicant, which is not published at the moment, PCT/IB2012/053624, a machine and a method using this machine, the method comprising a step of carrying out a plasma treatment for removing an initial outermost coating layer of a coated optical lens, and a step of depositing a final coating by vacuum evaporation in the same chamber. This solution provides to deposit a final coating on a cleaned surface without taking the lenses out of the cleaning chamber. The liquid composition used to form the final coating must be evaporable.
The vacuum nebulization treatment of the machine according to the invention allows the deposition of compounds that could or could not be evaporated, so that a larger range of liquid coating composition can be used compared to the known evaporation treatment mentioned above.
Furthermore, the machine according to the invention is compact. Thus, the machine according to the invention can be placed at an optician's premises, the optician being easily able to use said machine.
Indeed, the machine of this invention may be operated by an optician without having to remove spectacle lenses and/or send them to the manufacturer. It is particularly intended for depositing an anti-soiling or anti-fogging topcoat on spectacles lenses of known or unknown provenance such as on solar lenses which are usually not coated by an inorganic anti-reflective coating, or replacing an existing anti-soiling topcoat due to either reduced performances or because the owner desire another kind of topcoat, such as an anti-fogging, or vice-versa. Further, other kind of topcoats may be deposited.
It will be noted that the term “nebulization” here corresponds to a conversion of a liquid to a fine spray or an atomization. Next, the expression “mist of aerosol droplets” here means that the nebulizer is configured to transform (nebulize) the liquid coating composition into a plurality of a liquid droplets arranged in suspension under the shape of a mist.
According to preferred features, said control unit is configured to control said nebulizer for coating said optical article with said predetermined coating composition.
According to preferred features, the machine further comprises a plasma generator configured to carry out a vacuum plasma treatment of said optical article in said vacuum chamber, said control unit being configured to control said plasma generator for removing an initial outermost coating, of said optical article, or for activating a surface of the optical article, and to cause said vacuum pump to suck gases from said vacuum chamber during vacuum plasma treatment.
In other words, the machine according to the invention is configured to coat or recoat the optical article first by applying a plasma treatment to the initial base coating and next by nebulizing a predetermined coating on the optical article.
The two distinct treatments are advantageously implemented in the same vacuum chamber of the machine so that the machine is simple and economic.
The vacuum pump is thus connected to the vacuum chamber between the two treatments successively carried out.
It will be noted that the plasma treatment is convenient because neither does it deteriorate the anti-reflective coating which is generally under the initial outermost coating, such as an anti-soiling or anti-fogging coating, nor does it deteriorates any surface polymeric film which could be present under the outermost coating in place of the anti-reflective stack, which could be the case of an universal adhesion coating described below, deposited for instance during a previous use of the invention.
According to features preferred as being very simple, convenient and economical for embodying the machine according to the invention:
According to preferred features, said nebulizer comprises a nozzle system and said machine further comprises a container which contains a determined volume of said predetermined coating composition and at least one conduit configured to connect said container to said vacuum chamber in order to allow a fluidic communication between said container and said nebulizer.
The machine according to the invention does not need to store the liquid coating composition into a container enabling to support high pressure, compared to usual spraying-cans.
Further there is no need for a propellant with boiling point lower than ambient temperature. This means that the container might be less sturdy than actual spraying cans and that an accidental breach of such container will not lead to a pulverization of the liquid composition into the atmosphere. Indeed, most of the energy needed to propel and nebulize the liquid into an aerosol is provided by the chamber being at vacuum pressure, while the container is never at a pressure much higher than atmospheric pressure.
According to features preferred as being very simple, convenient and economical for embodying the machine according to the invention:
It will be noted that the term “vacuum chamber” means that the pressure of the interior space of the chamber is for instance comprised between 100 mbar and 0.01 mbar or less at least at the start of the vacuum nebulization treatment.
The invention also provides a method for using such a machine as described above, comprising the steps of:
Like the machine according to the invention, the method using the machine is particularly simple, convenient and fast to implement.
According to features preferred as being very simple, convenient and economical for embodying the method according to the invention:
The description of the invention now continues with a detailed description of a preferred embodiment given hereinafter by way of non-limiting example and with reference to the appended drawings. In these drawings:
In this description, the expression “comprised between” used in connection with a range of values should be understood as including the specific upper and lower values of this range.
The spectacle lenses 28 are shown on
The machine 1 comprises:
The vacuum chamber 8 comprises an interior space 31 configured to receive the spectacle lenses 28 mounted on a spectacle frame.
In a variant, only one lens is mounted in the interior space 31, or two lenses, without the spectacle frame.
The vacuum chamber 8 further comprises a door 9 which is removable (see description of
The plasma generator 11 is directly connected to the vacuum chamber 8.
The plasma generator 11 generally comprises a high-frequency generator.
The evaporation device 10 and the nebulizer 40 are both placed in the vacuum chamber 8 (i.e. mounted on the door 9 of the vacuum chamber 8) (see below).
The polymerisation device 37 is directly connected to the vacuum chamber 8.
The polymerisation device 37 generally comprises light sources, such as ultraviolet (UV) light or infrared (IR) light.
The vacuum chamber 8 further comprises a first inlet port 14 and a second inlet port 34 both connected to the inlet circuit 12.
The vacuum chamber 8 further comprises a third inlet port 42 connected to the propelling circuit 47.
The machine further comprises a gas inlet valve 13 mounted on the inlet circuit 12 and an inlet valve 33 which is also mounted on the inlet circuit 12, parallel to the gas inlet valve 13.
The machine further comprises a spraying valve 41 mounted on the propelling circuit 47.
The vacuum chamber 8 further comprises an outlet port 16 connected to the outlet circuit 15.
The vacuum pump 20 is connected to the outlet circuit 15 by the intermediary of an admission port 21 of the vacuum pump 20 and by the intermediary of an exit port 22 of the vacuum pump 20 so that the outlet circuit 15 passes through the vacuum pump 20.
The machine 1 further comprises a pressure sensor 17 which is connected to the outlet circuit 15 by the intermediary of a branching point 18.
The machine 1 further comprises a vacuum valve 19 which is mounted on the outlet circuit 15, between the branching point 18 and the admission port 21 of the vacuum pump 20.
The machine 1 further comprises a filtering device 23 here formed by a gas filter.
The filtering device 23 is connected to the outlet circuit 15 by the intermediary of an entrance port 24 and an exhaust port 25 of said filtering device 23.
The exhaust port 25 is linked to the atmosphere.
The filtering device 23 is thus mounted at the end of the outlet circuit 15, after the vacuum pump 20.
The container 50 comprises a rigid casing 52 delimiting an internal space 51 which is configured to contain a determined volume of a predetermined liquid coating composition, such as an anti-soiling coating composition or an anti-fogging coating composition or an adhesion coating composition.
The container 50 comprises a propeller 53 (here a gas, such as air, at atmospheric pressure) for propelling the determined volume of the predetermined liquid coating composition from the internal space 51 in the propelling circuit 47 until the spraying valve 41 and the third inlet port 42.
The propelling circuit is here formed by a conduit 47 having a first portion connected both to the internal space 51 of the container 50 and to the spraying valve and a second portion connected both to the spraying valve and to the vacuum chamber 8 by the intermediary of the third inlet port 42.
The conduit 47 is configured to allow a fluidic communication between the container 50 and the nebulizer 40.
The control unit 2 comprises a data processing system comprising a microprocessor 3 having a memory 4, in particular non volatile, allowing a software application, in other words a computer program, to be loaded and stored therein, and which allows the method for recoating the spectacle lenses 28 to be carried out when it is executed in the microprocessor 3.
The non-volatile memory is for instance a read only memory.
The data processing system further comprises a memory 5, for instance volatile, allowing storage of data during the execution of the software and the implementation of the method.
The volatile memory 5 is for instance a random access memory or an electrically erasable programmable read only memory.
The control unit 2 further comprises a communication interface configured to communicate with the data processing system.
The communication interface is here formed by a graphic interface 6 and a keyboard 7.
The control unit 2 is configured to control and exchange data with the gas inlet valve 13, the nebulizer 40, the evaporation device 10, the plasma generator 11, the pressure sensor 17, the spraying valve 42, the vacuum valve 19 and the vacuum pump 20.
The vacuum chamber 8 comprises a displacement member 26 configured to slide the door 9 between its open and closed states.
The machine 1 comprises a first support 27 also mounted on the interior face of the door 9.
The first support 27 is configured to receive the spectacle lenses 28 mounted on the spectacle frame.
The open state of the door 9 enables the loading of the spectacle lenses 28 together with the spectacle frame on the first support 27.
The nebulizer 40 comprises a nozzle system 43 which is here mounted on the interior face of the door 9.
The third inlet port 42 is formed on the exterior face of the door 9 whereas the machine 1 further comprises a third outlet port 45 formed on the interior face of the door 9 and communicating with the third inlet port 42.
The conduit 47 passes through the nebulizer 40 and is connected to the third inlet port 42.
The nozzle system 43 here comprises two nozzle heads 44 directed towards the optical article 28.
Each nozzle head 44 here faces the second surface 36 of the respective lenses 28.
When the conduit 47 is connected and the spectacle lenses 28 are received on the first support 27, the door 9 can be moved from its open state to its closed state as shown on
In this closed state of the door 9, the spectacle lenses 28 together with the spectacle frame and the nozzle heads 44 are in the vacuum chamber 8.
The nebulizer 40 is configured to nebulize the predetermined coating liquid composition into a mist of aerosol droplets and the nozzle heads 43 are configured to direct said droplets towards at least one of the surfaces 35, 36 of the optical article 28, according to a conical or pseudo-conical direction.
The machine 1 further comprises a second support 29 mounted on the interior face of the door 9.
The second support 29 is configured to receive a crucible 30 which is configured to be imbibed with a second predetermined liquid coating composition, such as an anti-soiling coating composition or an anti-fogging coating composition.
The second support 29 forms a part of the evaporation device 10.
The evaporation device 10 is here formed by a heating module 32 mounted on the interior face of the door 9, connected both to the second support 29 and to a power supply source (not shown) in order to heat the second predetermined liquid coating composition via the crucible 30 and via the second support 29.
The open state of the door 9 enables the loading of the crucible 30 imbibed with the second predetermined liquid coating composition on the second support 29.
When the crucible 30 and the spectacle lenses 28 are received on their respective support 29, 27, the door 9 can be moved from its open state to its closed state as shown on
In this closed state, the door 9, the spectacle lenses 28 together with the spectacle frame and the crucible 30 imbibed with the second predetermined liquid coating composition are in the vacuum chamber 8.
In a convenient way, the machine 1 is thus configured to be provided to an optician who can use said machine 1 when the wearer of the spectacle lenses 28 comes into his shop.
The spectacle lenses 28 here comprises an ophthalmic lens substrate on which are coated firstly an anti-reflective coating layer and secondly an initial anti-soiling coating layer (which form a topcoat).
If the effects of the initial anti-soiling layer are decreased, which might happen after some months of wearing, the optician can recoat a new anti-soiling layer on the spectacle lenses 28.
In a variant, the initial coating layer is not an anti-soiling coating but an anti-fogging coating. After winter, the wearer may wish to replace the anti-fogging coating by an anti-soiling coating.
We will now describe in details the method for using the machine 1 in order to recoat the spectacle lenses 28 with an anti-soiling coating composition, in reference to
For that purpose, the optician takes the spectacle lenses 28 (step of selecting the optical article) and selects the adapted anti-soiling composition to recoat.
Here, the anti-soiling composition is a 1% liquid solution of chemical compound in HFE7100 solvent, which solvent is distributed by the 3M™ Company. More precisely, the chemical compound is OPTOOL® DSX from the DAIKIN Company.
The optician fills the container 50 with a determined volume, here 2 mL, of this composition. The container has a volume greater than 2 mL and the remaining volume is filled with air at atmospheric pressure. The determined volume is here injected with a syringe through a rubber cork (not represented) of the container 50.
In a variant, the container is a disposable container already pre-filled with the determined volume of the composition. In such case, the machine may comprise a connector member configured to perforate a membrane of the container to reach the liquid or to connect the conduit 47 to an internal conduit of the container, in order to put in fluidic communication the conduit 47 and the inside of the container where the liquid composition is present.
The optician opens the door 9 of the vacuum chamber 8 and at step 100 loads the spectacle lenses 28 on the first support 27. The lenses are here finished lenses of 65 mm diameter.
The optician closes the door 9 of the vacuum chamber 8.
Next, the optician starts the treatment program for recoating the spectacle lenses 28 via the keyboard 7 and the graphic interface 6.
The control unit 2 then takes over the recoat treatment.
The vacuum pump 20 is started at step 101 and the vacuum valve 19 is opened at step 102 in order to connect (a flow connection) the vacuum pump 20 to the vacuum chamber 8 for evacuating air from the interior space 31 of the vacuum chamber 8 via the outlet circuit 15. The vacuum pump 20 is thus able to suck the gases from the vacuum chamber 8.
The control unit 2 waits and takes pressure measurements via the pressure sensor 17 until the vacuum chamber pressure reaches about 0.4 mbar.
Optionally the gas inlet valve 13 is then opened at step 103 in order to allow gas to enter in the vacuum chamber 8 via the inlet circuit 12 to have a stable pressure in the vacuum chamber 8.
The gas is here atmospheric air.
The evacuation time of the vacuum chamber 8 is approximately 120 s.
The plasma generator 11 is then set at step 104 with a predetermined power and for a predetermined time in order to carry out the vacuum plasma treatment for removing the initial outermost anti-soiling coating on the spectacle lenses 28, which one wants to replace.
Here, the plasma generator power is about 50-200 W (5-20 W/L according to the volume of the vacuum chamber 8 which is here 10 L) and the time of the plasma treatment is approximately equal to 120 s.
The vacuum plasma treatment allows removal of all the initial outermost coating of the spectacle lenses 28 without damaging the anti-reflective coating.
Further, the plasma treatment allows activation of the surfaces 35 and 36 of the spectacle lenses 28, in particular the anti-reflective coating in order to increase the adherence properties.
The vacuum valve 19 is then closed at step 105 in order to disconnect (a flow interruption) the vacuum pump 20 from the vacuum chamber 8. The vacuum pump 20 is thus able not to suck the gases from the vacuum chamber 8.
During the plasma treatment, the gases sucked by the vacuum pump 20 are filtered by the filtering device 23 before exhausting to the atmosphere.
At this stage of the recoat treatment, the control unit 2 optionally implements a venting step 106, depending on the required pressure for nebulization.
At step 106, the inlet valve 33 is opened for a predetermined time, for instance 10-20 s, in order to vent the vacuum chamber 8 and raise the pressure in the chamber 8.
The inlet valve 33 is then closed to end the venting step 106.
Next, the vacuum valve 19 is opened at step 107 in order to reconnect (a flow connection) the vacuum pump 20 to the vacuum chamber 8 for evacuating said vacuum chamber 8. The vacuum pump 20 is thus able to suck the gases from the vacuum chamber 8.
When the ventilating step 106 is not carried out, the steps 105 and 107 of closing and opening the vacuum valve 19 are not compulsory and thus could be skipped.
The vacuum valve 19 is opened for a predetermined time, for instance about 20 s, until the vacuum chamber pressure reaches a required pressure for nebulization, for instance about 0.4 mbar.
The required pressure for nebulization depends on the material to nebulize. More generally, the pressure of the interior space of the vacuum chamber 8 is for instance comprised between 100 mbar and 0.01 mbar or less, preferably comprised between 10 mbar and 0.05 mbar, and more preferably comprised between 1 mbar and 0.1 mbar.
The control unit 2 is configured to control the pressure in the vacuum chamber 8 by taking measurements with the pressure sensor 17.
The container 50 containing the 2 mL of the 1% liquid solution of DSX in HFE7100 solvent is next connected to the conduit 47 at step 108.
The container 50, through use of gravity and/or of a connector member, is configured to be connected with the conduit 47 so that the latter is directly in contact with the liquid composition (in other words so that the conduit is immersed into the liquid in the container 50), without connecting it to the gas. This means that one has to pass at least part of the liquid into the conduit 47 before some gas may pass into the conduit 47.
At this stage of the recoat treatment, the control unit 2 optionally closes the vacuum valve 19 at step 109.
At step 110, the spraying valve 41 is opened in order to allow a fluidic communication between the container 50 and the nebulizer 40.
At step 111, the nebulizer 40 is set for a predetermined time of spraying valve opening in order to carry out the vacuum nebulization treatment (or vacuum spraying treatment) for recoating the spectacle lenses 28.
The liquid composition is thus expulsed from the container 50 into the vacuum chamber 8 through the nozzle heads 44 of the nebulizer 40.
The vacuum pump 20 is thus able to suck or not to suck the gases from the vacuum chamber 8 during the nebulization treatment.
It is the difference in pressure, between the container 50, which initially has an internal pressure close to atmospheric pressure, and the vacuum chamber 8, which drives the liquid composition to be expulsed by the expanding propeller gas at a speed which allows an atomization of the liquid composition to create a mist of aerosol droplets directed towards the lenses 28 according to a predetermined conical or pseudo-conical direction.
This means that steps 110 and 111 which are here illustrated as two distinct steps form in reality a unique step relating to the nebulization treatment. Indeed, it is the opening of the spraying valve 110 that starts said nebulization treatment.
It will be noted that the pressure in the container is preferably smaller or close to atmospheric pressure. By smaller or close to atmospheric pressure, one means the pressure is comprised between 1 bar and 500 mbar included, preferably between 1 bar and 800 mbar, preferably between 1 bar and 950 mbar. As the container 50 may have been made at a time and place with an atmospheric pressure slightly different than the atmospheric pressure of the time and place the machine 1 is used, one considers that the pressure inside the container 50 can be as high as 1.1 bar. It might even be much higher that atmospheric pressure in case the local atmospheric pressure is low, such as 0.9 bar, eg in altitude or during low pressure weather.
Indeed, when the spraying valve 41 between the vacuum chamber 8 and the container 50 is opened, the propeller, here a gas, has to adjust to a difference of pressure with a ratio of 2500 (1 bar divided by 0.4 mbar). This means that, roughly, notwithstanding any drop in temperature, the gas wants to expand by a factor of 2500.
Thus, in order to expand into the vacuum chamber 8, the gas has to expel first the liquid composition into the conduit 47 and then into the vacuum chamber 8.
As the change in pressure is steep, the speed of the expulsion of the liquid composition is great, and the liquid composition reaches inside the conduit 47 a speed sufficient to nebulize it at the time it quits the conduit 47 through the nozzle heads 44.
The nozzle heads 44 are here distributed by Spraying system Co. under reference “veejet H-U ¼ inch 50/10”.
Each nozzle head 44 is positioned at a predetermined distance from the spectacle lenses 28, here about 4.5 cm.
The spraying valve 41 is then closed at step 112 in order to disconnect (a flow interruption) the container 50 from the vacuum chamber 8 (or the nebulizer 40).
During the nebulization treatment, the anti-soiling coating composition is thus nebulized in the vacuum chamber 8 and the mist of aerosol droplets is deposited on the surfaces of the spectacle lenses 28 present in front of the nozzle heads 44 in the form of a wet coating comprising the anti-soiling compound in solvent.
It will be noted that, during the vacuum nebulization treatment, the gas inlet valve 13 can stay closed and the vacuum valve 19 can be closed to have a pressure in the vacuum chamber 8 untroubled by sucking from the vacuum pump 20. In variant, during the vacuum nebulization treatment, the gas inlet valve 13 and/or the vacuum valve 19 might stay open to have a pressure in the vacuum chamber 8 regulated by the combined working of the sucking from the vacuum pump and the gas inlet valve 13. As mentioned above, the machine 1 might be configured so that the vacuum pump does not suck gas from the chamber during the vacuum nebulization treatment.
Next, a drying and venting step 113 is carried out equilibrating the chamber pressure with atmospheric pressure and evaporating the solvent that contains the liquid composition deposited on the lenses 28.
The gas inlet valve 33 and the vacuum valve 19 are opened for a predetermined time, for instance 60 s, in order to dry the lenses 28 and vent the vacuum chamber 8 and the gas inlet valve 13 and the vacuum valve 19 are then closed.
It will be noted that the drying step corresponds to an evaporation step (insomuch as drying is understood for all solvents and not only water). The opening of the gas inlet valve 33 creates a target pressure. The target pressure and the pumping rate of the vacuum pump 20 will be chosen depending on the solvent that needs to be evaporated and especially depending on the vapour pressure of the solvent at the temperature of the vacuum chamber 8 after the vacuum nebulization treatment. The pumping rate and target pressure might be determined so that the evaporation of the solvent is not so quick that it would carry compounds deposited on the lenses 28 or that it would create turbulences or strains on the liquid composition deposited.
The recoat treatment is thus finished.
The anti-soiling coating composition has been consumed and at step 114, the container 50 is disconnected from the conduit 47.
The optician opens the door 9 of the vacuum chamber 8.
There are no environmental or health risks because all the toxic gases have been filtered and the air during the treatment has been exhausted.
Here, 2 mL of 1% liquid solution of DSX in HFE7100 solvent is enough to recoat at least one surface of each of the two spectacle lenses by vacuum nebulization treatment. In a variant, such volume might be enough to recoat up to four surfaces. In the case of DSX, the topcoat mostly needs a monolayer of compounds to produce its effects. Thus 2 ml of this solution are enough to cover at least four surfaces of lenses, such as recoating simultaneously both surfaces of two lenses mounted on one pair of spectacles.
At step 115 the optician unloads the spectacle lenses 28 which are recoated with a new anti-soiling coating.
The optician may have to wipe the spectacle lenses 28 with a cloth to remove excess anti-soiling material or to wash them with a cleaning solution, such as IPA (“isopropyl alcohol or isopropanol”).
It will be noted that the performances of the recoating are here measured with a contact angle obtained after the nebulization treatment.
The contact angle measured is here equal to about 112° which is the contact angle expected for DSX coated lenses.
The contact angle may be measured using for instance a goniometer from Kruss after applying 3 to 5 drops of water with a unit volume of 4 μl onto the lenses previously washed.
It may be that the wearer wishes to add an anti-soiling coating or an anti-fogging coating on the lenses of his spectacle lenses, or that he wishes to replace the initial anti-fogging coating by an anti-soiling coating, and that the optician doesn't know either the composition of the anti-reflective coating or if there is even an anti-reflective coating on the lenses.
There is a risk relative to the adhesion of the new topcoat on the anti-reflective coating or on the lens without anti-reflective coating.
We will now describe in details the method for using the machine 1 in order to first deposit an universal adhesion layer on the spectacle lenses 28 and next recoat the spectacle lenses 28 with a new anti-soiling coating composition, in reference to
The method of
The optician takes the spectacle lenses 28 (step of selecting the optical article) and selects an adapted adhesion liquid composition to coat and the adapted anti-soiling composition to recoat. Alternatively, the control unit may select the adapted adhesion liquid composition depending on input given by the optician.
The adhesion liquid composition comprises monomers that may polymerize into a polymeric coating.
Here, the adhesion liquid composition, which consists of an adhesion promoter in a solvent, is a 1% solution of 3-aminopropyl-tris(methoxy-ethoxyethoxy)silane present in water, and the anti-soiling composition is the same as mentioned above, a 1% liquid solution of DSX in HFE7100 solvent.
In variant, the adhesion liquid composition might be a 1% solution of γ-glycidoxypropyl trimethoxy-silane (GLYMO) in methanol. In such case, the adhesion liquid composition deposited may need an activation using a plasma treatment in order to activate the polymerization of the adhesion liquid composition deposited.
The optician fills a first container 50 with a determined volume, here 2 mL, of the adhesion composition.
The optician opens the door 9 of the vacuum chamber 8 and at step 100 loads the spectacle lenses 28 and next closes the door 9 of the vacuum chamber 8.
The optician starts the treatment program for recoating the spectacle lenses 28 via the keyboard 7 and the graphic interface 6. The control unit 2 then takes over the recoat treatment.
The vacuum pump 20 is started at step 101 and the vacuum valve 19 is opened at step 102.
Optionally the gas inlet valve 13 is then opened at step 103.
The plasma generator 11 is then set at step 104.
The plasma treatment is not sufficient to activate the surfaces 35 and 36 of the spectacle lenses 28.
The vacuum valve 19 is then closed at step 105.
At this stage of the recoat treatment, the control unit 2 optionally implements a venting step 106 where the inlet valve 33 is opened for a predetermined time. The inlet valve 33 is then closed to end the venting step 106.
Next, the vacuum valve 19 is opened at step 107 for a predetermined time in order to evacuate said vacuum chamber 8 and until the vacuum chamber pressure reaches a required pressure for first nebulization, for instance about 0.4 mbar.
The predetermined required pressure might be adapted in order to reduce the speed of the nebulized droplets in the aerosol mist so as to enable the deposition of a thicker liquid layer, if needed. Such parameter might be adapted depending on the viscosity of the adhesion liquid composition, so as to increase the quantity of adhesion promoter material to be deposited on the spectacle lenses 28.
The control unit 2 is configured to control the pressure in the vacuum chamber 8 by taking measurements with the pressure sensor 17.
The first container 50 filled with the adhesion composition is next connected to the conduit 47 at step 116.
At this stage of the recoat treatment, the control unit 2 optionally closes the vacuum valve 19 at step 117.
At step 118, the spraying valve 41 is opened in order to allow a fluidic communication between the first container 50 and the nebulizer 40.
At step 119, the nebulizer 40 is set for a predetermined time of spraying valve opening in order to carry out the first vacuum nebulization treatment (or spraying treatment) for coating the spectacle lenses 28.
The adhesion liquid composition is thus expulsed from the container 50 into the vacuum chamber 8 through the nozzle heads 44 of the nebulizer 40.
The vacuum pump 20 is able to suck or not to suck the gases from the vacuum chamber 8 during the first nebulization treatment.
It is the difference in pressure, between the container 50, which initially has an internal pressure close to atmospheric pressure, and the vacuum chamber 8, which drives the adhesion liquid composition to be expulsed by the expanding propeller gas at a speed which allows an atomization of the adhesion liquid composition to create a mist of aerosol droplets directed towards the lenses 28 according to a predetermined conical or pseudo-conical direction.
This means that steps 118 and 118 which are here illustrated as two distinct steps form in reality a unique step relating to the nebulization treatment. Indeed, it is the opening of the spraying valve 119 that starts said nebulization treatment.
It will be noted that the pressure in the container 50 is preferably smaller or close to atmospheric-pressure.
The nozzle heads 44 are similar to the nozzle heads mentioned above.
Each nozzle head 44 is positioned at a predetermined distance from the spectacle lenses 28, here about 4.5 cm.
The spraying valve 41 is then closed at step 120 in order to disconnect (a flow interruption) the first container 50 from the vacuum chamber 8 (or the nebulizer 40).
During the first nebulization treatment, the adhesion composition is nebulized in the vacuum chamber 8 and the mist of aerosol droplets is deposited on the surfaces of the spectacle lenses 28 present in front of the nozzle heads 44 in the form of a wet coating comprising the adhesion compound, to form a thick liquid layer at this stage.
Next, a drying step 121 can be carried out for evaporating the solvent that contains the liquid composition deposited on the lenses 28.
The gas inlet valve 33 and the vacuum valve 19 are opened for a predetermined time in order to dry the lenses 28 and the gas inlet valve 13 and the vacuum valve 19 are then closed.
Next, a polymerization treatment can be carried out at step 122, depending on the adhesion composition used.
The polymerization might not need any external source and naturally happens, due to the thinness of the deposited coating and the high surface energies involved.
In variant, the polymerization might need activation and the control unit 2 thus activates the polymerization device 37 and set with a predetermined power and for a predetermined time in order to polymerize the universal adhesion coating. Such polymerization device might be a UV lamp in case the deposited liquid comprises photo activators mixed with photo activated monomers or photopolymers, or the polymerization device might be a IR lamp or might even be the plasma generator in some cases.
It will be noted that the drying step 121 and the polymerization step 122 can be carried out in the same time, or successively.
The first nebulization treatment is thus finished.
The adhesion liquid composition has been consumed and, at step 123, the first container 50 is disconnected from the conduit 47.
Next, the vacuum valve 19 is opened at step 124 for a predetermined time in order to evacuate said vacuum chamber 8 and until the vacuum chamber pressure reaches a required pressure for second nebulization, for instance about 0.4 mbar.
The control unit 2 is configured to control the pressure in the vacuum chamber 8 by taking measurements with the pressure sensor 17.
A second container 50 is filled with the 2 mL of the 1% DSX in HFE7100 solvent and connected to the conduit 47.
The method of
The second container 50 is connected to the conduit 47 at step 108.
At this stage of the recoat treatment, the control unit 2 optionally closes the vacuum valve 19 in step 109.
At step 110, the spraying valve 41 is opened in order to allow a fluidic communication between the second container 50 and the nebulizer 40.
At step 111, the nebulizer 40 is set for a predetermined time of valve opening in order to carry out the second vacuum nebulization treatment for recoating the spectacle lenses 28.
The liquid composition is thus expulsed from the container 50 into the vacuum chamber 8 through the nozzle heads 44 of the nebulizer 40.
Each nozzle head 44 is positioned at a predetermined distance from the spectacle lenses 28, here about 4.5 cm.
It is the opening of the spraying valve 110 that starts said nebulization treatment. Thus, the steps 110 and 111 form in reality a unique step relating to the nebulization treatment.
The spraying valve 41 is then closed at step 112.
During the second nebulization treatment, the anti-soiling coating composition is nebulized in the vacuum chamber 8 and the mist of aerosol droplets is deposited on the surfaces of the spectacle lenses 28 present in front of the nozzle heads 44 in the form of a wet coating comprising the anti-soiling compound in solvent.
Next, a drying and venting step 113 is carried out equilibrating the chamber pressure with atmospheric pressure and evaporating the solvent that contains the liquid composition deposited on the lenses 28.
The gas inlet valve 33 and the vacuum valve 19 are opened for a predetermined time, for instance 60 s, in order to dry the lenses 28 and vent the vacuum chamber 8 and the gas inlet valve 13 and the vacuum valve 19 are then closed.
The recoat treatment is thus finished.
The anti-soiling coating composition has been consumed and at step 114, the second container 50 is disconnected from the conduit 47.
The optician opens the door 9 of the vacuum chamber 8.
At step 115 the optician unloads the spectacle lenses 28 which are now recoated with a new anti-soiling coating. The optician may have to wipe the spectacle lenses 28 with a cloth to remove the excess of anti-soiling material, or wash it using IPA as noted above.
We will now describe in details the method for using the machine 1 according to a variant.
The method illustrated in
The method of
The optician opens the door 9 of the vacuum chamber 8 and, respectively at step 130 and 100, loads the crucible 30 and the spectacle lenses 28 on the second support 29 and on the first support 27, respectively.
The crucible 30 has previously been imbibed with a predetermined volume of the new anti-soiling liquid coating composition (which is similar to the composition mentioned above and which forms here the second predetermined liquid coating composition).
The optician fills the container 50 with a determined volume, here 2 mL, of the adhesion composition.
The optician closes the door 9 of the vacuum chamber 8 and starts the treatment program for recoating the spectacle lenses 28 via the keyboard 7 and the graphic interface 6. The control unit 2 then takes over the recoat treatment.
The vacuum pump 20 is started at step 101 and the vacuum valve 19 is opened at step 102.
Optionally the gas inlet valve 13 is then opened at step 103.
The plasma generator 11 is then set at step 104.
The plasma treatment is not sufficient to activate the surfaces 35 and 36 of the spectacle lenses 28.
The vacuum valve 19 is then closed at step 105.
At this stage of the recoat treatment, the control unit 2 optionally implements a venting step 106 where the inlet valve 33 is opened for a predetermined time. The inlet valve 33 is then closed to end the venting step 106.
Next, the vacuum valve 19 is opened at step 107 for a predetermined time in order to evacuate said vacuum chamber 8 and until the vacuum chamber pressure reaches a required pressure for nebulization, for instance about 0.4 mbar.
The control unit 2 is configured to control the pressure in the vacuum chamber 8 by taking measurements with the pressure sensor 17.
The container 50 filled with the adhesion composition is next connected to the conduit 47 at step 116.
At step 117, the spraying valve 41 is opened in order to allow a fluidic communication between the container 50 and the nebulizer 40.
At this stage of the recoat treatment, the control unit 2 optionally closes the vacuum valve 19 in step 118.
At step 119, the nebulizer 40 is set for a predetermined time on the valve opening in order to carry out the vacuum nebulization treatment for coating the spectacle lenses 28.
The adhesion liquid composition is thus expulsed from the container 50 into the vacuum chamber 8 through the nozzle heads 44 of the nebulizer 40.
The nozzle heads 44 are similar to the nozzle heads mentioned above and are each positioned at a predetermined distance from the spectacle lenses 28, here about 4.5 cm.
The spraying valve 41 is then closed at step 120.
During the nebulization treatment, the adhesion composition is nebulized in the vacuum chamber 8 and the mist of aerosol droplets is deposited on the surfaces of the spectacle lenses 28 present in front of the nozzle heads 44 in the form of a wet coating comprising the adhesion compound.
Next, a drying step 121 can be carried out for evaporating the solvent that contains the adhesion liquid composition deposited on the lenses 28.
The gas inlet valve 33 and the vacuum valve 19 are opened for a predetermined time in order to dry the lenses 28 and the gas inlet valve 13 and the vacuum valve 19 are then closed.
Next, a polymerization treatment can be carried out at step 122, depending on the adhesion composition used.
The polymerization treatment is natural and thus does not need any light source; or is forced and the control unit 2 sets the polymerization device 37 with a predetermined power and for a predetermined time in order to polymerize the layer of universal adhesion coating.
The drying step 121 and the polymerization step 122 can be carried out in the same time, or successively.
The nebulization treatment is thus finished.
The adhesion liquid composition has been consumed.
Next, the vacuum valve 19 is opened at step 124 for a predetermined time in order to evacuate said vacuum chamber 8 and until the vacuum chamber pressure reaches a required pressure for nebulization, for instance about 0.4 mbar.
The control unit 2 is configured to control the pressure in the vacuum chamber 8 by taking measurements with the pressure sensor 17.
The vacuum valve 19 is then closed at step 125 in order to disconnect (a flow interruption) the vacuum pump 20 from the vacuum chamber 8. The vacuum pump 20 is thus able not to suck the gases from the vacuum chamber 8.
The heating module 32 of the evaporation device 11 is then set at step 126 for a predetermined time at a predetermined current in order to reach a predetermined temperature of the heating module 32.
The predetermined time is about 30-50 s and the predetermined heating temperature is about 350° C. Heat load time and temperature depend on evaporation pressure and precursor used.
The heat of the heating module 32 is at least partially transferred to the crucible 30 and thus to the anti-soiling coating liquid composition which is imbibed.
Then, the heating step is stopped and the evaporation treatment continues (step 126) for a predetermined time which is for instance equal to 60-180 s.
During the evaporation treatment, the anti-soiling coating composition is evaporated in the vacuum chamber 8 and the vapour is deposited on the spectacle lenses 28.
Next, the vacuum valve 19 is opened at step 127 in order to reconnect (a flow connection) the vacuum pump 20 to the vacuum chamber 8 for evacuating said vacuum chamber 8, and in particular for evacuating the gases emitted during the vacuum evaporation treatment because such gases might be toxic. The vacuum pump 20 is thus able to suck the gases from the vacuum chamber 8.
The gases are sent from the vacuum pump 20 to the filtering device 23 where the gases are filtered at step 128.
The filtering step 128 is carried out for a predetermined time, for instance about 120 s.
The vacuum valve 19 is then closed at step 129 so that the vacuum pump 20 is disconnected (a flow interruption) from the vacuum chamber 8. The vacuum pump 20 is thus able not to suck the gases from the vacuum chamber 8.
As in step 106, a venting step 113 is carried out equilibrating the chamber pressure with atmospheric pressure. The venting step 113 is identical to the venting steps 106 and 121 (there is no drying here).
The gas inlet valve 33 is opened for a predetermined time, for instance 60 s, in order to vent the vacuum chamber 8 and the gas inlet valve 13 is then closed.
The recoat treatment is thus finished.
The optician opens the door 9 of the vacuum chamber 8.
There is no risk because all the toxic gases have been filtered and the air during the treatment has been exhausted.
The anti-soiling coating composition has been consumed.
At steps 114, 131 and 115 the optician respectively disconnects the container 50, unloads the crucible 30 and unloads the spectacle lenses 28 which are recoated with a new anti-soiling coating.
The crucible 30 may in fact be a disposable product.
It will be noted that the term “nebulization” in this application corresponds to a conversion of a liquid to a fine spray or an atomization. Next, the expression “mist of aerosol droplets” here means that the nebulizer is configured to transform (nebulize) the liquid coating composition into a plurality of a liquid droplets arranged in suspension under the shape of a mist.
It will further be noted that the term “vacuum chamber” means that the pressure of the interior space of the chamber is for instance comprised between 100 mbar and 0.01 mbar included or less at least at the start of the vacuum nebulization treatment, preferably between 10 mbar and 0.05 mbar included, and more preferably between 1 mbar and 0.1 mbar included.
It will further be noted that the term smaller or close to atmospheric pressure” means the pressure is comprised between 1 bar and 500 mbar included, preferably between 1 bar and 800 mbar, and more preferably between 1 bar and 950 mbar. As the container may have been made at a time and place with an atmospheric pressure slightly different than the atmospheric pressure of the time and place the machine is used, one considers that the pressure inside the container be as high as 1.1 bar. It might even be much higher that atmospheric pressure in case the local atmospheric pressure is low, such as 0.9 bar, eg in altitude or during low pressure weather.
It will be noted that the deposited coating might be a predetermined liquid coating composition that can be evaporated and used according to any of the embodiments illustrated in
The deposited coating might be a polymeric layer that can be deposited in order to improve the deposition performances of a further topcoat layer. In particular when one desires to deposit such topcoat on top of a lens surface of unknown origin, one may need the deposition of an universal adhesion layer comprising an adhesion promoter.
It will be noted that the adhesion promoter present in the adhesion liquid composition can be one of 3-amino-propyltrimethoxysilane (APTMS), 3-aminopropyltriethoxysilane (APTES), 3-aminopropyl-tris(methoxyethoxy-ethoxy) silane, acetamido propyltrimethoxysilane, γ-glycidoxypropyl trimethoxy-silane (GLYMO), γ-glycidoxypropyltriethoxysilane, and mixtures thereof, or other compounds of same properties
The deposited coating may be a complex hybrid compound, comprising for instance metallic or mineral particles or nanoparticles. It might comprise a mix of chemical compounds with some having different boiling points than others or even having either no boiling point, such as materials that only degrades with heat, or very high boiling points, typically higher than 500° C. or 1000° C. It might comprise monomers or mix of monomers in order to form polymeric materials. It might even comprise active compounds such as dyes, photochromic dyes, electrochromic materials, liquid crystals, photo-activators, ionic salts, etc.
The predetermined liquid coating compositions to be deposited may be any sprayable liquid solution. It is useful to provide the needed compound in a solvent to render the compound sprayable. The solvent is for instance water, or ethanol, or methanol, or HFE7100, or IPA, or acetone or other solvents.
The predetermined liquid coating composition has a concentration of compound into the solvent which might vary from 0.01% up till 100%. Preferably the total concentration of compounds in the solvent might be comprised between 0.1% and 10%, and more preferably between 0.5% and 5% included.
The predetermined liquid coating composition has a concentration of compound vs. solvent which depend on the viscosity of solvent and chemical compounds.
The viscosity of the predetermined liquid coating composition to be sprayed might depend on the solvent used if any. One objective of the use of solvent is to enable the solution to have a viscosity low enough so that it may attain a speed at which it is nebulized when propelled out of the nozzle due to the difference in pressure between the initial pressure inside the container and the pressure inside the vacuum chamber right before the opening of the spraying valve.
The necessary determined volume of predetermined liquid coating composition may vary depending on the final thickness of material needed, the concentration of compounds in the solution and the amount of the nebulized liquid which is sprayed outside of the surface to be treated.
The nebulizer can comprise multiple inlets for driving nebulized aerosol droplets into the chamber, providing multiple outputs into the chamber.
The container may be connected to a conduit that separates in two or four tubes in order to provide two or four outputs able to provide projection cones. The separation may be before the nozzle system device and in such case, there are multiple inlets and outlets penetrating the chamber. In a variant, the separation may be placed inside the chamber and, in that case, there may be only one inlet in the nebulizer. The multiple outlets may be organized to be able to each face one surface of the optical article. In case of spectacle glasses, comprising two lenses, there can be four outlets in order to have a projection of the aerosol droplets directed to each of the two surfaces of the two lenses.
In all the cases it is interesting that the conduit connecting the container and the vacuum chamber has an opening immersed in the liquid composition into the container, so that the expansion of the air push the liquid first into the tubing toward the inlet, and not the air, or other gas or propeller first. The container and conduit might be arranged so that gravity pulls the liquid to the opening of the conduit. In a variant, the machine might comprise a moveable extension inked to the conduit or inherent to the container, the extension being configured to plunge toward a position where the liquid is pulled by gravity.
The nozzles system might be able to move into position and/or the chamber might comprise means to move the holder of the optical article to position it in front of the different nozzle heads.
The distance between the nozzle heads and the surfaces of the optical article might be comprised between about 1 cm and about 10 cm, preferably between about 2 cm and about 8 cm, and more preferably between about 4 cm and about 6 cm.
The nozzle system may reduce the solid angle of the sprayed aerosol cone, but it may also shape it into a pseudo-cone with a non-circular cross-section.
Further, the nozzle may control or adapt the diameter of the projection, impacting the outgoing speed and dispersion of the nebulized coating.
The nozzle system can be used to deposit films on the surface of multiple optical articles, the amount of solution, the concentration of compound, the width of the pseudo-cone and the distance to the nozzle head(s) may be adapted with different values.
The nozzle system can be used to deposit as little material out of the surface of the optical article to be covered as possible.
One may be able to adapt the shape of the nozzle, the distance of projection, the exact vacuum pressure, the relative position and orientation of the projection pseudo-cone with the surface to be covered depending on the liquid layer deposited (compound and solvent), the material of the surface to be covered, the geometry, both shape and curvature, of the surface to be covered and the formulation, the surface tension and the viscosity of the sprayable liquid, and the initial pressure inside the container.
By adjusting the exact vacuum pressure and the initial pressure inside the container, one may manipulate the force imposed on the liquid to expel it from the container.
By adjusting the shape of the nozzle, the distance and orientation of the pseudo-cone, one may manipulated the shape and the local density of the cone or pseudo-cone at the moment the droplets impacts the surface to be covered.
Both aspects may enable to manipulate the speed of the nebulized droplets.
All those parameters may be manipulated in order either to adapt the liquid to the available machine or conversely adapt the machine to the solution available.
The solution might be placed in a rigid container or a deformable container, such as a rubber or plastics.
In a variant, the vacuum valve is not used to cause the vacuum pump to suck or not to suck gases from the vacuum chamber, but rather the control unit is configured to directly put on and put off the vacuum pump (flow connection and flow interruption).
In variants that are not illustrated, the machine does not comprise the plasma generator but comprises the nebulizer and optionally the evaporation device and/or the polymerization device and:
In further variants that are not illustrated:
It should be noted more generally that the invention is not limited to the examples described and represented.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2013/000548 | 1/22/2013 | WO | 00 |
