Device and method for curing a polymer layer on a cylindrical body

Abstract

The invention relates to a curing device (20) for curing a polymer layer on a cylindrical substrate (1), comprising a UV lighting device (21) for generating UV light and providing the UV light at a light opening (21a); a curing gap (27) which is arranged in front of the light opening (21a); an inert gas supply device (22) for supplying inert gas to the curing gap (27) upstream of the light opening (21a); a flow of inert gas through the curing gap (27); and an oxygen measuring device (37) for measuring the oxygen content in the inert gas downstream of the light opening (21a).

Description

[0001] Apparatus and method for curing a polymer layer on a cylindrical body

[0002] The invention relates to a curing device for curing a polymer layer on a cylindrical substrate.

[0003] Such a substrate can be, for example, a printing form that can be coated with a polymeric coating material. The term "substrate" or "printing form" is used below as a generic term for gravure printing forms, relief printing forms, or structural forms for embossing, but also for coating rollers or inking rollers.

[0004] WO 2021 / 052641 A1 discloses a printing form and a polymeric coating material therefor. The coating material is a polymeric nanocomposite that can be built up as a single layer for printing forms. The polymeric nanocomposite is applied in flowable form to the cylindrical outer surface of the printing form and subsequently cured by irradiation with UV light. The resulting polymer layer can be structured, for example, using infrared lasers to create a surface structure that has, for example, cells or structures for ink absorption or embossing, as also described in WO 2021 / 052641 A1.

[0005] Applying and curing a still-flowing polymer, such as the nanocomposite mentioned above, is complex. Curing is primarily achieved with UV light. To achieve efficient and low-emission (i.e., ozone-free) curing, UV LEDs are increasingly being used. These LEDs rely on surface inerting due to the predominant oxygen inhibition of the surface during radical polymerization.

[0006] Since the polymer coating is to be applied to substrates with different dimensions, in particular different lengths and diameters, UV radiation curing should be provided regardless of format and circumference, with minimal inert gas consumption.

[0007] The invention is therefore based on the object of providing a curing tool that can be used flexibly for different circumferences and format widths of cylindrical substrates. This object is achieved according to the invention by a curing device having the features of claim 1. Advantageous embodiments are specified in the dependent claims.

[0008] A curing device is specified for curing a polymer layer on a cylindrical substrate, comprising a UV light device for generating UV light and providing the UV light at a light opening; a curing gap arranged in front of the light opening; an inert gas supply device for supplying inert gas to the curing gap upstream of the light opening; an inert gas flow through the curing gap; and an oxygen measuring device for measuring the oxygen content in the inert gas downstream of the light opening.

[0009] The coated substrates can be rollers of all kinds, in particular printing forms such as gravure forms or cylinders, structural forms or cylinders, embossing forms or cylinders as well as relief printing forms or cylinders or coating rollers as well as inking rollers, e.g. for flexographic printing.

[0010] The polymer material was applied to the outer surface of the substrate in a suitable manner before the curing process and is still flowable in this state, i.e. before curing.

[0011] The polymeric coating material can be, for example, the material described in WO 2021 / 052641 A1. In particular, the polymer can be used as a coating material for coating a printing form, comprising a liquid starting material that is polymerizable by UV light to form a polymer matrix, a filler that has a sub-microscale size, wherein the coating material contains, in addition to the sub-microscale filler, a further filler, wherein the sub-microscale filler is in particle form and whose size is in a range between 100 nm and 999 nm, wherein the further filler is a nanoscale filler such that the further filler has filler particles with a nanoscale size in a range between 1 nm and 99 nm, wherein the sub-microscale filler consists of at least one metal oxide and / or a semimetal oxide selected from metal oxide-coated mica,TiO2 or (Sn, Sb)O2, wherein the nanoscale filler comprises metal and / or semi-metal oxides selected from Al2O3, SiO2, TiO2, ZrO2, or organometallic particles, wherein the sub-microscale filler is covalently incorporated into a polymer matrix of the starting material, wherein the nanoscale filler is included to increase wear resistance and is covalently incorporated into the polymer matrix of the starting material, and wherein the sub-microscale filler in the starting material can achieve an absorption of IR radiation that is higher than the absorption without filler.

[0012] The UV light device generates UV light, which exits the light aperture and from there can be applied directly to the polymer layer to be cured on the substrate. For this purpose, the curing gap is positioned in front of the light aperture and forms a narrow inerting and irradiation channel. The formation of the curing gap or channel can be ensured by precisely positioning the curing device relative to the polymer surface (and thus the substrate surface), as will be explained later.

[0013] The curing gap is at least partially open to the polymer layer to be cured. In particular, the curing gap is at least partially open on its side facing the substrate. The curing gap can have a gas inlet for admitting the inert gas and a gas outlet for discharging the inert gas. In the curing gap itself, the light opening is arranged opposite the polymer layer to enable curing of the polymer layer by irradiation with UV light.

[0014] The oxygen measuring device is used to measure the oxygen content in the inert gas discharged from the light opening. In particular, the residual oxygen content in the inert gas is measured. To achieve the desired protective effect of the inert gas on the polymer layer, the inert gas must have a specific concentration, which can be determined indirectly by measuring the residual oxygen content in the inert gas stream. For this purpose, the oxygen measuring device can be equipped with a lambda probe (Z-probe). Based on the results of the residual oxygen measurement, the required amount of inert gas can be adjusted and supplied at the upstream end via the inert gas supply device. This ensures a constant supply of inert gas in the curing gap during UV irradiation. At the same time, excessive inert gas consumption can be prevented, allowing the curing process to be carried out economically and in a resource-efficient manner.

[0015] Nitrogen is particularly suitable as an inert gas, providing sufficient inerting power. The curing device allows for the curing of a polymer layer on a cylindrical substrate, regardless of the substrate's shape or format.

[0016] The light opening on the UV light unit can be covered with UV-transparent quartz glass. This quartz glass cover in front of the UV light unit seals the gas flow in the curing gap, preventing inert gas from escaping into the rest of the work area.

[0017] The UV light device can in particular be an LED-based light device in which UV light is generated using LEDs.

[0018] A positioning device can be provided for positioning the UV light device. In this case, positioning means holding and / or moving the curing device or UV light device relative to the polymer layer to be cured or the substrate. The desired curing gap should be maintained as precisely as possible to ensure a reliable supply of inert gas.

[0019] For this purpose, a distance measurement can be provided, using, for example, an inductive, capacitive, or laser-based measuring principle. The distance can be variably controlled or precisely adjusted mechanically. This depends on the specific conditions regarding the positioning of the curing device relative to the substrate.

[0020] The positioning device may comprise a distance control device, wherein the distance control device comprises a distance measuring device for measuring the distance between the UV light device and a surface of the polymer layer and / or a surface of the substrate. The distance control device may comprise a distance setting device for adjusting the distance of the UV light device from the surface of the polymer layer and / or the surface of the substrate such that the distance corresponds to a predetermined value.

[0021] A gas delivery device can be provided to generate the inert gas flow through the curing gap. The gas delivery device can be arranged, in particular, downstream of the curing gap, and the gas delivery device can also be arranged downstream of the oxygen measuring device. The inert gas flow can be guided from the inert gas supply device through the curing gap and the oxygen measuring device by the action of the gas delivery device. The gas delivery device can, in particular, comprise a fan, with which a corresponding flow effect can be generated by sucking in the air and the inert gas.

[0022] The inert gas supply device can be configured to supply inert gas from an inert gas source to a gas inlet of the curing gap. The inert gas supply device can comprise a dispensing nozzle for introducing the inert gas into the curing gap. The inert gas supply device can comprise a calming section upstream of the gas inlet to reduce turbulent flows in the supplied inert gas. The inert gas source can be, for example, a tank or a gas cylinder.

[0023] The inert gas should be introduced across the entire width of the curing gap, if possible, to achieve a uniform, ideally laminar, inert gas flow through the curing gap. This is possible with the help of the inert gas injection nozzle, which spreads the inert gas accordingly. Furthermore, a calming section can be provided as part of the inert gas supply device or injection nozzle directly before the inert gas enters the curing gap, which calms the flow and makes it largely laminar. The injection nozzle can be implemented as a type of slot nozzle.

[0024] The inert gas supply device can include a mass flow controller for regulating the flow of inert gas from the inert gas source. The mass flow controller allows the precise adjustment of the amount of inert gas supplied to the curing gap per unit of time.

[0025] Downstream of the curing gap, a gas outlet can be provided through which inert gas exits the curing gap, wherein a gas discharge device can be provided downstream of the gas outlet, wherein the gas discharge device can have a measuring chamber feed which is arranged at the gas outlet and via which inert gas exiting the curing gap can be guided to a measuring chamber, and wherein the oxygen measuring device is designed to measure the oxygen content in the measuring device.

[0026] The gas outlet defines the end of the curing gap. Immediately thereafter, a portion of the inert gas can be captured and discharged by the gas discharge device. The remaining inert gas escapes into the atmosphere. The portion of the inert gas captured and discharged by the gas discharge device is fed into the measuring chamber, where the oxygen measuring device can measure the (residual) oxygen content in the inert gas. This allows the inert gas supply control described above to always ensure a sufficient amount of inert gas is fed into the curing gap so that the polymer surface is exposed to a gas with a correspondingly low oxygen content, preventing oxidation processes during UV curing of the polymer.

[0027] A residual oxygen control device may be provided, which includes the oxygen measuring device and is designed to maintain the oxygen content measured by the oxygen measuring device within a predetermined range. In this way, the inert gas content in the gas stream is also indirectly determined.

[0028] In practice, it has been found that a residual oxygen content of 0.1% to 10%, in particular 0.5% to 5%, should be set, depending on the curing behavior of the polymer mixture.

[0029] The residual oxygen control device can be coupled to the mass flow controller to control the supply of inert gas.

[0030] The gas conveying device (e.g. the fan) can be provided at the downstream end of the gas discharge device.

[0031] The curing gap, the gas inlet, and the gas outlet can be at least partially sealed from the environment by a non-contact seal. The non-contact seal can, for example, comprise one or more layered sheet metal or plastic elements. For example, the non-contact seal can also be implemented using a skived doctor blade. The skived doctor blade or the associated sheet metal or plastic elements generate a turbulent flow to prevent the escape of inert gas. This enables an almost laminar inert gas flow between the gas inlet and the gas outlet. The turbulent flow in the area of ​​the non-contact seal represents a flow obstacle, so that only a reduced amount of inert gas can escape to the environment there.

[0032] A curing system for curing a polymer layer on a cylindrical substrate is specified, comprising a curing device according to one of the preceding claims; a substrate holder for supporting the cylindrical substrate; a translation device for moving the curing device in a translation direction; a rotation device for moving the substrate supported by the substrate holder in a rotation direction; and a movement controller configured to coordinate the movement by the translation device with the movement of the rotation device such that the curing device performs a spiral movement relative to the substrate.

[0033] In this way, the curing device can be moved relative to the rotating substrate to cure the polymer. The translation direction can be, in particular, the longitudinal direction of the substrate, e.g., its central axis, while the substrate itself is rotated about its main axis or central axis. The desired relative spiral movement can be achieved through the superimposed movement of the rotation of the substrate and the translation of the curing device. This allows the polymer to be cured evenly on the surface of the substrate. In particular, the polymer can be cured seamlessly and effectively due to the resulting spiral path of the UV radiation.

[0034] A method for curing a polymer layer on a cylindrical substrate is provided, comprising the steps:

[0035] Generating UV light and providing the UV light at a light opening;

[0036] Supplying inert gas to a curing gap arranged in front of the light opening upstream of the light opening;

[0037] Generating an inert gas flow through the curing gap; and

[0038] Measuring the oxygen content in the inert gas downstream of the light opening.

[0039] These and other features and advantages of the invention are explained in more detail below using examples with the aid of the accompanying figures. They show:

[0040] Fig. 1 shows a coating system for applying a polymer layer to a cylindrical substrate;

[0041] Fig. 2 shows a coating device as part of the coating system of Fig. 1, for coating a cylindrical substrate with a polymer;

[0042] Fig. 3 is a sectional side view of the device of Fig. 2;

[0043] Fig. 4 is an enlarged detail "C" of Fig. 2; Fig. 5 is a curing system for curing a polymer layer on a cylindrical substrate;

[0044] Fig. 6 shows a curing device as part of the curing system of Fig. 5;

[0045] Fig. 7 is an enlarged detail of the hardening device of Fig. 6; and

[0046] Fig. 8 is a partial sectional side view of the hardening device of Fig. 6.

[0047] Fig. 1 shows a perspective view of a coating system as part of a layer production system for producing a polymer layer on a cylindrical substrate 1.

[0048] In the example shown, the substrate 1 is a printing form, namely a gravure cylinder for use in gravure printing. The gravure cylinder is to be coated with a flowable polymer. This can be, for example, the nanocomposite known from WO 2021 / 052641 A1. The polymer coating of the gravure cylinder is suitable for laser treatment, in particular with a near-field infrared (NIR) laser, to create small depressions, so-called cells, which can absorb the printing ink and transfer it to the object to be printed. For this purpose, the polymer layer must have a relatively small thickness (layer thickness), e.g. 10 / zm to 500 / zm, in particular 10 / zm to 250 / zm.

[0049] The substrate 1 or the gravure cylinder is held rotatably in a direction of rotation R in a holder not shown.

[0050] A coating device 2 is provided on the outside of the substrate 1, which can be moved in a translation direction X along the outside of the substrate 1. The coating device 2 serves to apply the still-flowable polymer material to the cylindrical surface of the substrate 1.

[0051] When the translational movement of the coating device 2 in the translation direction X and the rotation of the substrate 1 in the rotation direction R are superimposed, the coating device 2 performs a spiral movement relative to the outside of the substrate 1, as shown in Fig. 1 by an arrow S. As a result, flowable polymer material with a width of, for example, a few millimeters, for example 5 mm to 30 mm, can be applied to the outside of the substrate 1 using the coating device 2. Due to the spiral relative movement, one polymer layer can be applied next to the other in a spiral or helical manner, so that ultimately the entire outer surface of the substrate or part of it is uniformly covered with a polymer layer.With the help of smoothing elements, which will be explained later, a gap that arises between the adjacent polymer layers can be closed uniformly, so that a uniform, homogeneous polymer layer is created.

[0052] To apply the polymer material, the coating device 2 must maintain a uniform, very close distance from the substrate surface. For this purpose, the coating device 2 can be moved in the radial direction Z of the substrate 1 by a coating positioning device (not shown). For this purpose, the coating positioning device can comprise a distance control device with a distance measuring device 3. Depending on the embodiment, the distance measuring device 3 can operate as an inductive, capacitive, or laser-based distance sensor and support the distance control.

[0053] Figs. 2 to 4 show the coating device 2 in detail, wherein Fig. 2 represents a main section, Fig. 3 a sectional side view of Fig. 2 and Fig. 4 an enlarged detail C of Fig. 2.

[0054] The coating device 2 comprises a carrier body 5. A feed nozzle 6 is held in the carrier body 5, to which coating material 7 in the form of a flowable polymer material is fed. The coating material 7 can be fed by a continuous, pulsation-free, and precise material feed, e.g., using syringe pumps or eccentric screw pumps (dispensers).

[0055] The feed nozzle 6 has a cylindrical material feed 8 that tapers conically toward an outlet opening 9. The outlet opening 9 can have a depth T of, for example, 1 to 3 mm and a width B of 5 to 30 mm, although other dimensions are also possible.

[0056] In addition, the feed nozzle 6 can taper toward the outlet opening 9 (material outlet) at a taper angle. A taper angle a of, for example, 1° to 7° ensures laminar flow and an increasing fluid velocity of the coating material 7 shortly before the material exits.

[0057] It has been found that at distances between the feed nozzle 6, or in particular the outlet opening 9 of the feed nozzle 6, and the substrate 1 in the range of 1xS to 4xS, where S is the desired layer thickness on the substrate 1, a sufficiently large meniscus or heel is created at the nozzle outlet, ensuring complete wetting across the entire nozzle width. A constant distance thus also results in a constant layer thickness.

[0058] Downstream of the feed nozzle 6, as seen in the direction of rotation, a smoothing blade 10 is attached to the carrier body 5 to smooth the surface of the polymer material applied to the substrate 1. The smoothing blade 10 can be, for example, a plastic sheet. The plastic surface of the smoothing blade 10 is well suited to achieving the desired surface quality on the smoothed polymer.

[0059] A support squeegee 11 is arranged on the back of the smoothing squeegee 10, extending over the entire back surface of the smoothing squeegee 10. The support squeegee 11 can be made of spring steel. The support squeegee 11 thus supports the shape of the smoothing squeegee 10 and ensures a sufficiently large pressure force of the smoothing squeegee 10 on the polymer to be smoothed or spread.

[0060] Fig. 4 shows the smoothing squeegee 10 and the supporting squeegee 11 in an enlarged view.

[0061] At the front of the smoothing blade 10, a return blade 12, also made of steel or spring steel, is provided, which extends over a partial surface of the smoothing blade 10 (Fig. 4). For example, the return blade 12 can extend over half or one-third of the surface of the smoothing blade 10.

[0062] The doctor blades 10, 11, 12 are jointly attached laterally to a doctor blade attachment 13 on the carrier body 5.

[0063] Located at the rear of the smoothing squeegee 10 is a pressure piston 14, which is actuated and moved by a pneumatic cylinder 15, which in turn is controlled by compressed air via a pneumatic supply 16. The compressed air in the pneumatic cylinder 15 can press the pressure piston 14 downward against the support squeegee 11 and thus against the smoothing squeegee 10, thus pressing the support squeegee 11 with the smoothing squeegee 10 against the return squeegee 12. The return squeegee 12 exerts a counterforce against the action of the pressure piston 14, so that a force equilibrium is established depending on the applied air pressure. This allows the contact force of the smoothing squeegee 10 against the polymer material to be smoothed to be precisely adjusted.

[0064] The contact pressure of the smoothing blade 10 on the applied polymer layer can be adjusted using a control system. Excessive contact pressure leads to a significant change in the layer distribution, while insufficient contact pressure prevents the transition gap between the individual spiral coatings from closing. It has been shown that, due to different viscosities, surface tensions, and other material variables, a range of surface pressures of the smoothing blade 10 on the polymer material must be feasible.

[0065] The width of the smoothing blade 10 can be two to three times, up to five times, or up to ten times the width of a spiral layer in order to ensure a large contact surface and uniform layer homogenization.

[0066] Fig. 5 shows a curing system as a further part of the layer production system for producing a polymer layer on a cylindrical substrate. The components shown in Fig. 5 can, in particular, represent a supplement to the components shown in Fig. 1, so that the entire layer production system combines the components of Figs. 1 and 5, i.e., first applying a layer of a flowable polymer to the substrate 1 and then curing the polymer layer on the substrate 1.

[0067] Accordingly, in the curing system of Fig. 5, it is assumed that the substrate 1 is already covered with a flowable polymer layer, which now has to be cured in order to become dimensionally stable and to be able to serve its actual purpose, e.g. as a gravure printing roller.

[0068] The substrate 1, e.g. the gravure roller, is - as in the system of Fig. 1 - still held in the holder not shown and rotated in the direction of rotation R.

[0069] A curing device 20 is arranged on the circumference of the substrate 1, which cures the polymer layer using UV light.

[0070] The entire layer generation system formed with components of Figs. 1 and 5 can thus comprise the coating device 2 shown in Fig. 1 and the curing device 20. This allows a polymer layer to be first applied to the outer surface of the substrate 1 by the coating device 2 and subsequently cured by the curing device 20 using UV light irradiation. In both process steps, the substrate 1 can be rotated about its main or longitudinal axis, while the coating device 2 and the curing device 2 are moved along the outer surface.

[0071] When UV curing polymers using LEDs, there is a risk that the free radicals of the photoinitiator released by the UVA radiation from the LED will be bound by atmospheric oxygen, thus preventing complete surface curing. Therefore, UV irradiation must be carried out in an inert gas atmosphere. To achieve this, the curing device 20 comprises not only a UV light device 21 but also an inert gas supply device 22.

[0072] Analogous to the coating device 2 in Fig. 1, the curing device 20 also has a curing translation device (not shown) with which the curing device 20 can be moved in a translation direction X along the longitudinal axis of the substrate 1. Parallel to this, the substrate rotates in the rotation direction R, resulting in the spiral movement S. In this way, the curing device 20 can cover the entire surface of the polymer layer applied to the outer surface of the substrate 1 with the UV light device 21 and thus cure the polymer.

[0073] Similar to the coating device 2 described above, the curing device 20 also has a curing positioning device (not shown) with a distance control device for adjusting the distance of the curing device 20 in the Z direction, i.e., in the direction of the surface of the substrate 1 (radial direction of the substrate 1). A distance measuring device 23 is provided for this purpose. Precise maintenance of the distance is important for achieving a satisfactory curing result.

[0074] Fig. 6 shows the curing device 20 in an enlarged sectional view. The curing device 20 is shown in relation to two substrates 1a, 1b of different sizes to illustrate that the curing device 20 can be used for substrates 1 with significantly different diameters.

[0075] Approximately in the middle, the curing device 20 has the UV light device 21, which is arranged vertically in the example shown and at the bottom of which the UV light can emerge via a light opening 21a (Fig. 7), as will be explained later.

[0076] The inert gas supply device 22, located to the right of the UV light device 21 in Fig. 6, has a gas supply line 24 through which inert gas is supplied from a storage device, e.g., a gas cylinder or a gas tank. Nitrogen is particularly suitable as an inert gas. The flow of the inert gas to the light opening 21a of the UV light device 21 is controlled by a mass flow controller 25. This will be explained in more detail later.

[0077] Fig. 7 shows the area below the UV light device 21 in an enlarged view compared to Fig. 6. The light opening 21a, which serves as the exit opening of the UV light device 21 and through which the UV light exits to irradiate the polymer material, is covered by a UV-transparent quartz glass cover 26.

[0078] A curing gap 27 is formed between the UV light device 21 or the quartz glass cover 26 on the one hand, and the surface of the substrate 1 covered with the polymer layer, spaced therefrom, on the other hand. Upstream of the quartz glass cover 26 and the curing gap 27, the inert gas supply device 22 has a dispensing nozzle 28, through which the inert gas can be introduced into the curing gap 27 via a gas inlet 29. The dispensing nozzle 28 is arranged at the end of a dispensing funnel 30, which is followed by a dispensing channel 31, as shown in Fig. 8.

[0079] Fig. 8 shows a section through the induction channel 31 of Fig. 7. It can be clearly seen that the inert gas supplied via a gas line 32 from the mass flow controller 25 is fanned out in the induction funnel 30 and subsequently calmed in the narrow induction channel 31. In the induction channel 31, which also serves as a calming section, a substantially laminar flow of the inert gas can be achieved, so that the inert gas can be discharged over the entire width of the induction nozzle 28 and can cover polymer material on the substrates 1a, 1b before this region of the polymer material, then protected by inert gas, reaches the light opening 21a on the quartz glass cover 26 in the curing gap 27, where the UV irradiation takes place.

[0080] After leaving the injection nozzle 28, it is to be expected that the inert gas will partially mix with atmospheric oxygen, since the area of ​​the gas inlet 29 into the curing gap 27 cannot be completely sealed from the environment. Thus, the curing gap 27 is not flowed through by pure inert gas, but rather by a gas mixture that, in addition to inert gas, will also contain residual oxygen components. The sealing measures provided to reduce the ingress of ambient air, as well as the measures to achieve a specified proportion of inert gas in the gas mixture, will be explained later.

[0081] Downstream of the quartz glass cover 26 or the curing gap 27, i.e., after UV irradiation, the curing gap 27 ends at a gas outlet 33. A gas discharge device 34 with a downstream measuring chamber 35 is provided there. The gas discharge device 34 can, in particular, be designed as a gap and create a connecting channel from the end of the curing gap 27 (gas outlet 33) to the measuring chamber 35. A portion of the inert gas is thus discharged via the gas discharge device 34 or to the measuring chamber 35, while another portion of the inert gas, not captured by the gas discharge device 34, can escape to the environment.

[0082] To reduce inert gas leaks or losses into the environment, the curing gap 27 is sealed on all sides, i.e., on all four sides, by non-contact seals, which are designed, in particular, as doctor blade seals 36. The doctor blade seals 36 comprise one or more sheet metal elements arranged in staggered rows and representing flow obstructions, so that the inert gas cannot flow out unhindered. This, and in conjunction with a gas conveying device (described later), ensures that only a relatively small portion of the inert gas escapes into the environment, while the remaining portion is extracted via the measuring chamber.

[0083] A lambda probe (X-probe) 37 is provided in the measuring chamber 35 as part of an oxygen measuring device. With the help of the oxygen measuring device, the (residual) oxygen content in the inert gas downstream of the location of the UV irradiation at the light opening 21a can be measured. This allows the inflow of inert gas or the ratio of inert gas to oxygen to be regulated using the mass flow controller 25 in order to, on the one hand, keep the residual oxygen content within a predetermined range and, on the other hand, also keep the inert gas content within a predetermined range in order to ensure effective protection of the polymer surface from oxidation during UV irradiation. A residual oxygen content of 0.1% to 10%, in particular of 0.5% to 5%, depending on the curing behavior of the polymer mixture, has proven suitable. The inert gas flow is effected by means of a gas conveying device 38, which has an exhaust fan 39.The exhaust fan 39 creates a negative pressure with which the gas mixture is extracted from the inert gas supply device 22 via the curing gap 27. The gas flow thus occurs via the gas supply line 24, the mass flow regulator 25, the gas line 32, the induction funnel 30, the induction nozzle 28, the curing gap 27, the gas discharge device 34, the measuring chamber 35, and the exhaust fan 39.

Claims

Patent claims 1. A curing device (20) for curing a polymer layer on a cylindrical substrate (1), comprising a UV light device (21) for generating UV light and providing the UV light at a light opening (21a); ​​a curing gap (27) arranged in front of the light opening (21a); ​​an inert gas supply device (22) for supplying inert gas to the curing gap (27) upstream of the light opening (21a); ​​an inert gas flow through the curing gap (27); and an oxygen measuring device (37) for measuring the oxygen content in the inert gas downstream of the light opening (21a).

2. Curing device (20) according to claim 1, wherein the light opening (21a) is covered with a UV-transparent quartz glass (26).

3. Curing device (20) according to one of the preceding claims, wherein a positioning device is provided for positioning the UV light device (21 a).

4. Curing device (20) according to one of the preceding claims, wherein the positioning device comprises a distance control device; the distance control device comprises a distance measuring device (23) for measuring the distance between the UV light device (21) and a surface of the polymer layer and / or a surface of the substrate (1); and wherein the distance control device comprises a distance setting device for adjusting the distance of the UV light device (21) to the surface of the polymer layer and / or the surface of the substrate (1) such that the distance corresponds to a predetermined value.

5. Curing device (20) according to one of the preceding claims, wherein a gas conveying device (38) is provided for generating the inert gas flow through the curing gap (27).

6. Curing device (20) according to one of the preceding claims, wherein the inert gas supply device (22) is designed to supply inert gas from an inert gas source to a gas inlet (29) of the curing gap (27); the inert gas supply device (22) has a flushing nozzle (28) for introducing the inert gas into the curing gap (27); and wherein the inert gas supply device (22) has a calming section (31) upstream of the gas inlet (29) for reducing turbulent flows in the supplied inert gas. Curing device (20) according to one of the preceding claims, wherein the inert gas supply device (22) has a mass flow controller (25) for regulating the inflow of inert gas from the inert gas source.Curing device (20) according to one of the preceding claims, wherein a gas outlet (33) is provided downstream of the curing gap (27), through which inert gas exits the curing gap (27); a gas discharge device (34) is provided downstream of the gas outlet (33); the gas discharge device (34) has a measuring chamber feed, which is arranged at the gas outlet (34) and via which inert gas exiting the curing gap (27) can be guided to a measuring chamber (35); and wherein the oxygen measuring device (37) is designed to measure the oxygen content in the measuring chamber. Curing device (20) according to one of the preceding claims, wherein a residual oxygen control device is provided, which has the oxygen measuring device (37) and is designed to keep the oxygen content measured by the oxygen measuring device (37) within a predetermined range.Curing device (20) according to one of the preceding claims, wherein the gas conveying device (38) is provided at the downstream end of the gas discharge device (34).

1. Curing device (20) according to one of the preceding claims, wherein the curing gap (27), the gas inlet (29), and the gas outlet (33) are at least partially sealed from the environment by a non-contact seal (36). . Curing system for curing a polymer layer on a cylindrical substrate (1), comprising a curing device (20) according to one of the preceding claims. a substrate holder for holding the cylindrical substrate; a translation device for moving the curing device in a translation direction (X); a rotation device for moving the substrate carried by the substrate holder in a rotation direction (R); and a movement control configured to coordinate the movement by the translation device with the movement of the rotation device such that the curing device performs a spiral movement (S) relative to the substrate. A method for curing a polymer layer on a cylindrical substrate (1), comprising the steps Generating UV light and providing the UV light at a light opening (21a); Supplying inert gas to a curing gap (27) arranged in front of the light opening (21a) upstream of the light opening (21a); Generating an inert gas flow through the curing gap (27); and Measuring the oxygen content in the inert gas downstream of the light opening (21a).

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