Method for controlling coating glossy on coating line for rolling products

Abstract

FIELD: organic coating.SUBSTANCE: automated processes for the continuous application of a coating to metal before the manufacture of the final product. Invention concerns a method for controlling the gloss of an organic coating formed on a moving strip on a coil coating line. The coating line comprises a sequentially arranged paint application device, a cooling device containing a cooling module, an ultraviolet curing device and an electron beam curing device. The method includes correcting the deviation of the measured brightness G beyond the specified brightness range Rs. The correction includes a sub-step of calculating a correction CP applied to the power of the cooling module, at least in a section of the width upstream from the ultraviolet curing device, taking into account the value of Gs and the measured gloss G, using a feedback controller, as well as a sub-step of adjusting the setting parameter of the coil coating line taking into account the calculated correction CP.EFFECT: provides a method for efficiently and reproducibly controlling the gloss of an organic coating formed by applying and curing a wet film of radiation-cured paint on a moving strip on a coil coating line.15 cl, 4 dwg

Description

[0001] The present invention relates to a method for controlling the gloss of an organic coating applied to a moving strip in a coil coating line. Specifically, the moving strip is a steel strip with a metallic coating.

[0002] Coil coating is a continuous automated process for applying a coating to metal prior to manufacturing. Steel or aluminum substrates are delivered in coils from rolling mills. The metal coil is positioned at the beginning of the coil coating line. In a single, continuous process, the coil is unwound, pre-cleaned, treated, primed, and painted, then wound at the other end and packaged for shipping.

[0003] The product obtained through this process is pre-painted metal, also known as coil-coated metal, pre-finished metal, or pre-coated metal. It is widely used in construction and electrical equipment.

[0004] Solvent-based paints have traditionally been used to coat coiled products. However, there has been recent interest in radiation curing, which involves curing materials using ultraviolet light (UV-C) or electron beams (EB). These paints, known as radiation-curable (radcure) paints, are solvent-free, and the curing process is initiated either by exposure to high-energy UV light, possibly in combination with suitable photoinitiators, or by exposure to accelerated electrons. Photoinitiators absorb UV light and generate free radicals. These free radicals react with the double bonds of the monomers, causing a chain reaction and polymerization. UV-C and EB curing do not require initiators.High radiation energy ensures the formation of a sufficient number of active particles (radicals) for the spontaneous polymerization process.

[0005] One of the characteristics of radiation-cured paints is the creation of high-gloss organic coatings due to the high surface tension of the coating surface. To reduce this gloss and meet the requirements of the pre-painted surface market (gloss typically ranges from 15 to 30 gloss units (GU) for the construction market), paint suppliers add matting additives, just like in solvent-based paints. However, since radiation-cured paints are quite viscous due to the absence of solvent, only a small amount of matting agent can be added, which prevents low gloss levels from being achieved. Furthermore, the migration of matting additives to the coating surface to achieve the desired gloss level is also very limited due to the curing speed of radiation-cured paints (radcure) compared to solvent-based paints (1-2 seconds versus 12-25 seconds).

[0006] One solution to this problem is known from document WO81 / 00683, which discloses a curing process in which the coating is first irradiated with curing radiation at wavelengths to which it responds but with virtually no distribution below approximately 300 nm (e.g., UV radiation), and then irradiated with curing radiation at wavelengths to which the coating responds, including significant radiation at wavelengths below 300 nm (e.g., EB, EP). This dual curing is known as dual curing. Gloss control is achieved by adjusting parameters in real time, including the spectral distribution, intensity or dose of the initial radiation, and the time interval between the initial and subsequent irradiation stages.

[0007] However, it was noted that these real-time parameters are not sufficient for effective and reproducible gloss control.

[0008] Therefore, the object of the present invention is to eliminate the disadvantages of the prior art process by developing a method for efficiently and reproducibly controlling the gloss of an organic coating formed by applying and curing a wet film of radiation-cured paint on a moving strip on a coil coating line.

[0009] For this purpose, the first object of the present invention is a method for controlling the gloss of an organic coating formed by applying and curing a wet film of radiation-curable paint on a moving strip on a coil coating line, comprising, sequentially arranged along the path P of the moving strip: a paint application device, a cooling device containing a cooling module, an ultraviolet curing device, and an electron beam curing device. The method includes the steps of:

[0010] - setting the specified value Gs of organic coating gloss and the specified range Rs of organic coating gloss;

[0011] - collecting gloss measurement data G of the organic coating at least in a width section downstream of the electron beam curing device.

[0012] - corrections of the deviation of the measured brightness G beyond the specified brightness range Rs, wherein this stage of correction includes the sub-stage of calculating the correction C P , applied to the power of the cooling module, taking into account the value of Gs and the measured gloss G, using a feedback controller, and a sub-stage of adjusting the setting parameter of the rolling mill coating line taking into account the calculated correction C P .

[0013] The method according to the invention may also have the optional features listed below, considered individually or in combination:

[0014] - The feedback controller is a proportional-integral-differential controller,

[0015] - amendment C P is a function of the difference between the value of Gs and the measured brightness G,

[0016] - amendment C P , applied to the power of the cooling module, is calculated using equation 1:

[0017] (1)

[0018] where Kp is the proportional gain, Ki is the integral gain, Kd is the differential gain, and e1 is the difference between Gs and the measured luminosity G.

[0019] - the data collection step further includes collecting the measurement data of the wet film temperature T at least in a section of the width of the moving strip upstream of the ultraviolet curing device,

[0020] - the correction step further includes a sub-step of calculating the corrected temperature Tc that the wet film must reach at least in the width section downstream of the cooling module and upstream of the ultraviolet curing device,

[0021] - the corrected temperature Tc is calculated using equation 2:

[0022] Tc = f1(T, G, Gs) (2)

[0023] where function f1 is a predetermined mathematical relationship between the wet film temperature before UV curing and the gloss of the organic coating after electron beam curing,

[0024] - the corrected temperature Tc is calculated using equation 3:

[0025] Tc = T + K (G - Gs) (3)

[0026] - Amendment C P is a function of the difference between Tc and the measured temperature T,

[0027] - amendment C P , applied to the power of the cooling module, is calculated using equation 4:

[0028] (4)

[0029] where K'p is the proportional gain, K'i is the integral gain, K'd is the differential gain, and e2 is the difference between Tc and the measured temperature T.

[0030] - The method further includes a line initial setup step in which:

[0031] o collect data of several process parameters and / or strip characteristics,

[0032] o at least one initial line condition is set from the initial power PW0 of the cooling module, the initial UV dose D0 of the ultraviolet curing device and the initial distance L0 between the ultraviolet curing device and the electron beam curing device, taking into account the collected process parameters and / or strip characteristics,

[0033] - The sub-step of adjusting the setting parameter of the coil coating line includes adjusting the power of the cooling module using the C correction P ,

[0034] - UV curing device contains UV module,

[0035] - the installation stage additionally includes setting the minimum temperature Tmin for radiation-cured paint,

[0036] - the data collection stage additionally includes the collection of data on the UV dose D of the UV module,

[0037] - the sub-step of adjusting the setting parameter of the coil coating line includes:

[0038] o assess whether the Tc value is less than the Tmin value,

[0039] o If not, adjust the cooling module power using correction C P ,

[0040] o if Tc is less than Tmin:

[0041] ▪ calculate the corrected UV dose Dc to which the wet film must be exposed over at least the width portion in the UV module, according to equation 5:

[0042] C D = f2(G, Gs) (5)

[0043] ▪ adjust the setting parameter of the coil coating line, which is not the power of the cooling module, taking into account the calculated correction C D .

[0044] - the sub-step of adjusting the setting parameter of the coil coating line, which is not the power of the cooling module, includes adjusting the power of the UV module so that the wet film at least in the section of the width of the moving strip is exposed to the adjusted dose Dc = D + C D UV radiation,

[0045] - The UV module is movable along the path P,

[0046] - the installation stage additionally includes setting the minimum dose Dmin of UV radiation to which the wet film in the UV module can be exposed,

[0047] - the data collection step further includes collecting data on the distance L between the UV module and the electron beam curing device,

[0048] - the sub-step of adjusting the setting parameter of the coil coating line, which is not the capacity of the cooling device, includes:

[0049] ▪ assess whether the value is D + C D less than the value of Dmin,

[0050] ▪ if not, the power of the UV module is adjusted so that the wet film, at least over a section of the width of the moving strip, is exposed to the adjusted dose of UV radiation Dc = D + C D ,

[0051] ▪ if the value is D + C D less than the Dmin value:

[0052] • calculate the C correction L , applied to the distance between the UV module and the electron beam curing device, according to equation 6:

[0053] C L = f3(G, G s ) (6)

[0054] • adjust the setting parameter of the coil coating line, which is not the power of the cooling module and the power of the UV module, taking into account the calculated correction C L .

[0055] - the sub-step of adjusting the setting parameter of the coil coating line other than the power of the cooling module and the power of the UV module includes adjusting the distance between the UV module and the electron beam curing device to the adjusted distance Lc = L + C L in such a way that on the organic coating, at least in the section of the width of the moving strip downstream of the electron beam curing device, the gloss value Gs is achieved;

[0056] - The cooling module is selected from a forced air cooler, a water spray cooler, a water and air mist spray cooler, and a cooled roll.

[0057] A second object of the invention is a coil coating line comprising a sequentially arranged: a paint application device, a cooling device comprising a cooling module, an ultraviolet curing device, and an electron beam curing device. The coil coating line also comprises a gloss control tool for controlling the gloss of an organic coating formed by applying and curing a wet film of radiation-curable paint on a moving strip on the coil coating line; the gloss control tool comprises:

[0058] - the setting module that sets the set value Gs of organic coating gloss and the set range Rs of organic coating gloss;

[0059] - a data collection module that collects measurement data of the G gloss value of the organic coating at least in a width section downstream of the electron beam curing device;

[0060] - correction module that corrects the deviation of the measured brightness G beyond the specified brightness range Rs, and the correction includes a sub-stage of calculating the correction C P , applied to the power of the cooling module, taking into account Gs and the measured gloss G, using a feedback controller, as well as a sub-stage of adjusting the setting parameter of the rolled product coating line taking into account the calculated correction amendment Cp.

[0061] Other characteristics and advantages of the invention will be described in more detail in the following description.

[0062] The invention will be better understood after reading the following description, which is given for the purpose of explanation only and is in no way limiting, and is given with reference to:

[0063] - Fig. 1, which schematically shows the coating line of rolled metal;

[0064] - Fig. 2 - a block diagram of the sequence of execution of the first embodiment of the method according to the invention;

[0065] - Fig. 3 - a block diagram of the sequence of execution of the second embodiment of the method according to the invention;

[0066] - Fig. 4 is a flow chart of the sequence of execution of the third embodiment of the method according to the invention.

[0067] It should be noted that spatially relative terms such as "upstream", "downstream", "lower", "upper", "above", "below", "before", "after"..., as used in this application, refer to the position and orientation of the various components of the roll coating line.

[0068] The method according to the invention is intended for strips, such as metal strips. Examples of metal strips are steel (carbon or stainless), aluminum, copper. In particular, the steel strips can be either uncoated or with a metallic coating applied to one or both sides of the strip. Examples of possible steels with a metallic coating are hot-dip galvanized steel, steels coated with a zinc alloy containing 5 wt.% aluminum (Galfan®), steels coated with a zinc alloy containing 55 wt.% aluminum, about 1.5 wt.% silicon, the remainder consisting of zinc and unavoidable impurities due to processing (Aluzinc®, Galvalume®), steels coated with an aluminum alloy containing 8 - 11 wt.% silicon and 2 - 4 wt.% iron, the remainder consists of aluminum and unavoidable impurities resulting from processing (Alusi®), steels coated with a layer of aluminum (Alupur®), steels coated with a zinc alloy containing 0.5 - 20% aluminum, 0.5 - 10% magnesium, the remainder consists of zinc and unavoidable impurities resulting from processing, steels coated with an alloy containing aluminum, magnesium, silicon, possible additional elements, the remainder consists of zinc and unavoidable impurities arising during processing.

[0069] The method according to the invention is also intended for radiation-curable paints. The term "radiation-curable paints" refers to radiation-curable compositions that are "cured" or dried using short-wave ultraviolet (UV) radiation and / or high-energy electrons from electron-beam sources. They typically contain liquid monomers and oligomers in which pigments, fillers, additives, and photoinitiators can be dispersed, typically without the need for solvent or water. Thus, they are essentially solvent-free. Dual-curing radiation-curable paints preferably contain acrylate or methacrylate monomers and photoinitiators.

[0070] As shown in Fig. 1, the coil coating line 1 according to the invention mainly comprises, sequentially arranged along the strip movement path P: a paint application device 2, a cooling device 3 containing a cooling module, an ultraviolet curing device 4 and an electron beam curing device 5.

[0071] Path P is the path along which strip S runs from the entrance to the coil coating line to its exit. It has a width and a length. Equipment for strip handling is located along this path.

[0072] Paint applicator 2 is a device for applying a wet paint layer of a predetermined thickness to one or both sides of a strip. Specifically, its purpose is to apply a wet paint layer with radiation curing. The technology of the paint applicator is not limited in the context of the invention.

[0073] According to an embodiment of the invention, the paint applicator 2 is a roller applicator. This device is an automated machine for coating one or both sides of a strip using rotating rollers. It is designed such that the strip passes through the machine, which applies a layer of paint to one or both sides of the strip. There are many designs of roller applicators, depending on the configuration of the roll coating line, the types of paints used, and the types of strips to be coated. A person skilled in the art will know which design is best suited for each case. Typically, a roller applicator consists of a paint pan, a steel or ceramic gripper roller, and a rubber-coated coating roller. The purpose of the paint pan is to hold, circulate, and, preferably, heat the paint.The pickup roller can be partially immersed in the ink and can rotate either clockwise or counterclockwise to pick up the ink and transfer it to the coating roller, which then transfers the ink to the strip.

[0074] According to another embodiment of the invention, the paint application device 2 is a curtain coating device. In this case, a curtain of paint is applied in a layer onto a horizontal strip, typically perpendicular to the paint curtain. The paint falls from a height under the force of gravity from a die or cascade for delivering the curtain of paint, while the strip is supported by a support roller. This method enables high line speeds and multi-layer coating.

[0075] Examples of other paint applicator devices include knife type, dip or meniscus type, slot type, metering bar type, sliding type paint applicator.

[0076] Paint is typically applied by a paint applicator across the entire stripe width. By default, the wet paint film width, and therefore the organic coating, is equal to the stripe width.

[0077] The paint application device 2 is preferably equipped with at least one heating device for heating the paint and maintaining it at a predetermined temperature. Heating the paint facilitates its application. In the case of a roller coating device, the paint heater may be a tray heater, i.e., a heater located inside or around the tray. This may also be a temperature-controlled roller, in particular a temperature-controlled gripper roller, possibly in combination with a tray heater. In the case of a curtain coating device, the paint heating device may be a heater located upstream of the paint curtain application die. This may also be a temperature-controlled back-up roller, possibly in combination with a heater.

[0078] Paint applicator 2 is preferably equipped with a temperature measuring device for measuring the paint temperature and / or wet film temperature at the paint applicator. The temperature measuring device may be, for example, a temperature sensor, a pyrometer, or a thermal imager.

[0079] The coil coating line 1 further comprises a cooling device 3 comprising a cooling module arranged along the strip path P, downstream of the paint application device 2 and upstream of the ultraviolet (UV) curing device 4. Its purpose is to cool the radiation-cured wet paint film, especially when applying a wet film to a strip that is still warm after a previous step (e.g., curing a primer in an oven or after galvanizing), or at a high ambient temperature, such as in summer. The cooling device further improves the temperature control of the wet paint film before its curing in the UV curing device by compensating for fluctuations in the wet film temperature at the inlet of the UV curing device, which would otherwise result from fluctuations on the line.Indeed, since the strip temperature at the paint application unit's outlet decreases at a rate dependent on a number of parameters (strip type, strip width, strip thickness, line speed, ambient temperature, etc.), the wet film temperature at the UV curing unit's inlet can fluctuate significantly from time to time, negatively impacting gloss. A cooling unit allows for controlled wet film temperature control.

[0080] For cooling devices, forced-air coolers, water spray coolers, water-air mist coolers, and chill rolls are preferred. With water-based coolers, since the wet film of radiation-cured paint is applied to the top side of the strip, the water preferably only comes into contact with the back side of the strip. The cooling device does not act as a water reservoir.

[0081] In one embodiment, the cooling device is constructed as a single cooling module spanning the entire width of the moving strip path P. In this case, the wet film is cooled uniformly across its entire width as it passes through the cooling device.

[0082] According to another embodiment, cooling device 3 comprises multiple cooling modules distributed across the width of path P. In other words, multiple cooling modules form a row substantially parallel to the width of path P, i.e., perpendicular to the direction of strip travel. For clarity, the cooling modules described here are independent of one another and located adjacent to one another, but may be physically inseparable. They may be individually controllable parts of a single cooling device.

[0083] The cooling modules are preferably selected from the following: a forced air cooler, a water spray cooler, a water and air mist spray cooler, and a cooling roll.

[0084] This design corrects and minimizes temperature variations across the stripe width. Preferably, the wet film temperature variation across the stripe width at the cooling device outlet is less than 1°C. This improves the uniformity of coating gloss across the stripe width.

[0085] According to another embodiment, cooling device 3 comprises a base cooler, spanning the entire width of path P, and several cooling modules described above, arranged sequentially along the strip conveying path. The base cooler may comprise a forced-air cooler, a water spray cooler, a water and air mist cooler, or a cooling roller. With this design, part of the cooling required to achieve the correct wet film temperature at the cooling device outlet is provided by the base cooler. Each of the several cooling modules independently provides the remaining cooling and can regulate it as needed.

[0086] Cooling device 3 is preferably located above path P to directly cool the wet film applied to the upper side of the strip. The cooling device may also be located above and below path P to minimize temperature gradients.

[0087] Roll coating line 1 also includes ultraviolet (UV) curing unit 4. This equipment is designed to cure the surface of the wet paint film using radiation curing. It has been observed that surface curing creates a very fine texture on the film surface, which, combined with matting agents and other additives, contributes to the gloss of the organic coating after the wet film is fully cured using an electron beam.

[0088] According to one embodiment, the ultraviolet (UV) curing device 4 spans the entire width of the moving strip path P. In this case, the wet film surface is cured uniformly across the strip width under the influence of UV radiation.

[0089] According to another embodiment, the ultraviolet (UV) curing device 4 consists of multiple UV modules distributed across the width of the path P. In other words, multiple UV modules form a row substantially parallel to the width of the path P, i.e., perpendicular to the direction of strip travel. For clarity, the UV modules described here are independent of each other and located adjacent to each other, but may be physically inseparable. They may be individually controllable parts of a single ultraviolet (UV) curing device.

[0090] This design allows path / strip sections of different widths to be exposed to different UV doses. This helps correct and minimize gloss variations across the stripe width. Accordingly, the cooling device preferably comprises multiple cooling modules arranged in a row substantially parallel to the path width P, with each cooling module designed to cool a strip section that is then exposed to the UV radiation of a single UV module. In other words, each width section covered by a given UV module corresponds to the width section covered by the corresponding cooling module.

[0091] UVA (ultraviolet A) and UVB (ultraviolet B) are preferred. UVA is long-wave UV radiation with a wavelength of 320 to 400 nm. UVB is short-wave UV radiation with a wavelength of 280 to 320 nm. They can be produced with traditional UV arc lamps.

[0092] The ultraviolet (UV) curing device 4 is preferably movable along the path P of the moving strip. This allows the distance between the UV curing device and the electron beam curing device to be adjusted, i.e., lengthened or shortened. Indeed, it has been observed that wrinkles or surface roughness that arise during UV curing further develop in the period between UV curing and electron beam curing, affecting the gloss of the organic coating.

[0093] In the case of using multiple UV modules, each UV module is preferably configured to move along the path P independently of the others.

[0094] Roll coating line 1 also includes an electron beam curing unit 5. This equipment is designed to cure wet paint films using radiation curing, i.e., throughout their entire thickness. It also records the surface roughness that develops on the wet film surface during UV curing and continues to develop between UV curing and electron beam curing. The electron beam curing unit typically operates under the following conditions: 100-200 kV, 20-50 kGy, and an inert atmosphere containing nitrogen with an O2 concentration below 200 ppm.

[0095] The coil coating line 1 further comprises a wet film temperature measuring device 6, located downstream of the cooling device 3 and upstream of the UV curing device 4. This device measures the wet film temperature before it enters the UV curing device. It can measure the wet film temperature across the entire width of the path P of the moving strip or only within a section thereof. Examples of wet film temperature measuring devices include a pyrometer, a thermal imager, and a thermocouple. The measured temperature can be expressed in °C, °F, or K.

[0096] If the wet film temperature measuring device measures the temperature only in the width section, the measurement in this section can be considered significant enough to control the gloss across the entire width of the strip.

[0097] Alternatively, multiple wet film temperature measuring devices are arranged downstream of the cooling device 3 and upstream of the UV curing device so as to cover the entire width of the path P of the moving strip. They form a row substantially parallel to the width of the path P. Accordingly, the cooling device preferably comprises multiple cooling modules forming a row substantially parallel to the width of the path P, wherein each cooling module is designed to cool a section of the strip width, the temperature of which is then measured by a single wet film temperature measuring device.

[0098] To further enhance the control of the wet film temperature in the ultraviolet (UV) curing device, the wet film temperature measuring device 6 and the ultraviolet (UV) curing device 4 should be separated by no more than 2 meters, preferably no more than 1 meter, or the wet film temperature is measured no more than 4 seconds before the wet film is cured in the UV curing device, preferably no more than 2 seconds. Alternatively or additionally, the section of the path P of the moving strip between the wet film temperature measuring device and the UV curing device can be thermally insulated to maintain the wet film at the measured temperature until it is cured in the ultraviolet (UV) curing device.

[0099] The coil coating line 1 further comprises a gloss measuring device 7 located downstream of the electron beam curing device 5. This gloss measuring device measures the gloss of the organic coating after electron beam curing. It can measure the gloss of the organic coating over the entire width of the path P of the moving strip or only over a section of the width. Examples of gloss measuring devices are glossometers. The measured gloss is preferably expressed in gloss units (GU). Gloss is preferably measured in accordance with ISO 2813:2014 and EN 13523-2:2021. It is preferable to measure gloss using a 20°, 60°, or 85° geometry, that is, the reflection angle is 20°, 60°, or 85°. It is more preferable to measure gloss using a 60° geometry.

[0100] In case the gloss measuring device measures the gloss only in a width section, the measurement in this section can be considered significant enough to control the gloss over the entire width of the strip.

[0101] Alternatively, a plurality of gloss measuring devices are arranged downstream of the electron beam curing device so as to cover the entire path width P of the moving strip. They form a row substantially parallel to the path width P. Accordingly, the cooling device preferably comprises a plurality of cooling modules forming a row substantially parallel to the path width P, wherein each cooling module is intended to cool a portion of the strip width, the gloss of which is then measured by a single gloss measuring device. Accordingly, the UV curing device preferably comprises a plurality of UV modules forming a row substantially parallel to the path width P, wherein each UV module is intended to irradiate with UV radiation a portion of the strip width, the gloss of which is then measured by a single gloss measuring device.

[0102] Roll coating line 1 is preferably equipped with a strip speed measuring device, preferably located at the guide roll level. An example of a strip speed measuring device is a tachometer built into the roll axis.

[0103] The coil coating line 1 may further comprise an inductor 8 located upstream of the paint applicator 2. It can heat the strip before it reaches the paint applicator. Heating the strip in the paint applicator facilitates better paint application. Furthermore, the strip temperature achieved in the inductor can be adjusted to correct for possible gloss variations, as will be described in detail below.

[0104] The coil coating line 1 may further comprise an input section with an unwinding device 9 for unwinding the strip to be coated on the line. The unwinding device may be combined with a welding machine or stitching device, allowing the leading end of the strip to be coated to be attached to the trailing end of the preceding strip.

[0105] Alternatively, the coil coating line can be combined with the galvanizing line, resulting in the strip coated with metal alloys contained in the galvanizing line bath being directly coated with organic coating without the need for pre-coiling and uncoiling.

[0106] The coil coating line 1 may further comprise an input accumulator 10, located in the input section of the line, downstream of the uncoiler, if used. The accumulator is a piece of equipment that "accumulates" a certain amount of strip. It consists of a set of upper and lower groups of rolls through which the metal strip is passed in a serpentine pattern, and accumulates a strip of metal of a certain length by moving two rows of rolls apart. The total length of the stored metal depends on the design speed of the coil coating line, which is typically 60 seconds under steady-state metal processing conditions. After the input section of the coil coating line stops, the groups of rolls move toward each other, and the metal accumulated in the accumulator continues to be fed to the rest of the coil coating line.

[0107] The coil coating line 1 may further comprise a cleaning section 11 located downstream of the input section, in particular downstream of the input accumulator, if used. In this section, the strip undergoes a surface preparation step. This type of preparation includes at least one step selected from the following: washing, degreasing, and conversion treatment. The purpose of washing is to remove loose dirt particles, possible residues of conversion solutions, and soap that may have previously formed, and to obtain a clean and chemically active surface. The purpose of degreasing is to clean the surface by removing all traces of organic contaminants, metal particles, and dust. Preferably, degreasing is carried out in an alkaline environment.Conversion treatment involves applying a conversion solution to the strip, which reacts chemically with the surface, thereby forming a conversion layer. This layer improves paint adhesion and corrosion resistance. Conversion treatment is preferably performed with a chromium-free acid solution. More preferably, the conversion treatment is based on hexafluorotitanic or hexafluorozirconic acid.

[0108] The coil coating line 1 may further comprise a primer section located upstream of the paint applicator 2 and downstream of the cleaning section, if used. In this section, a first coat of paint may be applied to the strip to form a primer coating. The primer section may include a primer applicator and curing equipment. Depending on the type of primer, the curing equipment may be an oven, such as a convection oven, an infrared (or near-infrared) oven, or an induction oven, a UV curing device, and / or an electron beam curing device.

[0109] The coil coating line 1 may further comprise an output storage device 12 located in the output section of the line, downstream of the electron beam curing device. The output storage device is similar to the input storage device described above.

[0110] The coil coating line 1 may further comprise a coiler 13 for winding the strip coated on the line. The coiler may be combined with a cutting device for separating one strip from the next strip processed on the line.

[0111] The coil coating line 1 may further comprise a heating device located along the strip path P, adjacent to the cooling device. The heating device may be located either upstream or downstream of the cooling device. Its purpose is to replace the cooling device when the wet film of paint is insufficiently heated for curing in the ultraviolet (UV) curing device, even if the cooling device is operating at a minimum level or is turned off. The heating device allows for more precise wet film temperature control than using a cooling device alone.

[0112] The heating device is preferably selected from the following: an infrared heater, an induction heater, a convector, a forced-air heater, a water spray heater, a water-air mist heater, and a heated roller. Preferably, the heating device is an infrared heater. In the case of water-based heaters, since the wet film of radiation-cured paint is applied to the front side of the strip, the water preferably only contacts the back side of the strip.

[0113] In one embodiment, the heating device consists of a single heating module spanning the entire width of the moving strip path P. In this case, the wet film is heated uniformly across its entire width as it passes through the heating device.

[0114] According to another embodiment, the heating device comprises multiple heating modules distributed across the width of the path P. In other words, multiple heating modules form a row substantially parallel to the width of the path P, i.e., perpendicular to the direction of strip movement. For clarity, the heating modules described here are independent of each other and arranged adjacent to each other, but may be physically inseparable. They may be individually controllable parts of a single heating device.

[0115] The heating modules are preferably selected from the following types of heaters: infrared heater, induction heater, convector, forced-air heater, water spray heater, water-air mist heater, and roller heating width section. More preferably, the heating modules are infrared heaters.

[0116] This design corrects and minimizes temperature variations across the stripe width. Preferably, the wet film temperature variation across the stripe width at the heater outlet is less than 1°C. This improves the uniformity of coating gloss across the stripe width.

[0117] According to another embodiment, the heating device comprises a main heating element, spanning the entire width of the strip path P, and several heating modules, as described above, arranged sequentially along the strip conveying path. With this design, part of the energy required to achieve the desired wet film temperature at the outlet of the heating device is provided by the main heater. Each heating module independently provides the remaining energy and can regulate it as needed.

[0118] The heating device is preferably located above the P path to ensure direct heating of the wet film applied to the top side of the strip. The heating device may also be located above and below the P path to minimize temperature gradients.

[0119] The invention also relates to a tool for controlling the gloss of an organic coating formed by applying and curing a wet film of radiation-cured paint on a moving strip of a roll coating line 1 comprising, sequentially arranged along the path P of the moving strip S: a paint application device 2, a cooling device 3 containing a cooling module, an ultraviolet curing device 4 and an electron beam curing device 5.

[0120] The gloss control tool contains a setting module for setting the target value Gs of organic coating gloss and the target range Rs of organic coating gloss.

[0121] The gloss control tool also comprises a data collection module configured to collect gloss measurement data G of the organic coating at least over a width section downstream of the electron beam curing device. Preferably, the data collection module is further configured to collect wet film temperature data T over at least a width section of the moving strip downstream of the cooling module and upstream of the ultraviolet curing device.

[0122] The gloss control tool further comprises a correction module configured to correct the deviation of the measured gloss G from the specified gloss range Rs, wherein the correction includes a sub-step of calculating the correction C Р, applied to the power of the cooling module taking into account Gs and the measured gloss G, using a feedback controller, as well as a sub-stage of adjusting the setting parameter of the rolling coating line taking into account the calculated correction C Р .

[0123] The gloss control instrument may comprise a processing unit, for example, consisting of a memory and a processor connected to the memory. The electronic monitoring device may also comprise a display screen and input / output means, such as a keyboard and a mouse, each connected to the processing unit. Each module, including the setup module, data acquisition module, and correction module, may be implemented as software executed by the processor.

[0124] The coil coating line is preferably equipped with a gloss control tool to facilitate the gloss control on the coil coating line.

[0125] From a process perspective, the gloss control of the organic coating line formed during the application and curing of a wet film of radiation-curable paint on a moving belt in a coil coating line described above is primarily based on the discovery that the wet film temperature before UV curing plays a key role. Specifically, the inventors discovered that, in dual-curing coil coating, there is a relationship between the wet film temperature before UV curing and the gloss of the organic coating after electron beam curing. Therefore, any deviation in gloss after electron beam curing can be effectively and reproducibly corrected by adjusting the power of the cooling module and, consequently, the wet film temperature before UV curing.

[0126] The method is applied to a moving strip. The strip may be a single roll unwound at the entrance to a coil coating line. More commonly, the strip consists of several rolls joined end-to-end. The rolls form a single, substantially continuous strip, the properties and technical characteristics of which, achieved at the exit of the coil coating line, change over time. The strip moves along path P of the coil coating line, where it is coated with a wet film of radiation-cured paint, preferably heated, and undergoes dual curing.Specifically, the strip moves along path P of the coil coating line such that a wet film of radiation-curable paint is first applied to the strip by a paint applicator, then cooled by a cooling module, then exposed to UV radiation in an ultraviolet curing device, and finally cured in an electron beam device. Optionally, the strip can be preheated using an inductor 8 located upstream of the paint applicator 2. Optionally, the radiation-curable paint can be heated in the paint applicator.

[0127] The first embodiment of the method is described with reference to Fig. 2.

[0128] The first step of 100 gloss control method is to set some target values ​​required for correct regulation.

[0129] First, the target gloss value Gs for the organic coating is set. This value corresponds to the gloss requested by the customer or set by the coil coating line operator. For practical purposes, it can be manually entered into the gloss management tool, specifically the setup module. Alternatively, it can be automatically retrieved from the coil coating line order book, specifically from the planning tool.

[0130] Since small gloss deviations along the strip length are generally acceptable from a quality standpoint, a target gloss range Rs for the organic coating is also specified. It can be entered as a range per se—minimum and maximum gloss—or as a standard deviation from the target gloss value Gs. Of course, if for any reason minor deviations must be avoided, the target gloss value Gs can be entered as both minimum and maximum gloss, or the standard deviation can be set to zero. From a practical standpoint, the target gloss range Rs can be entered manually in the gloss management tool, specifically in the setup module. Alternatively, it can be automatically obtained from the coil coating line management tool or from the coil coating line order book, specifically from the planning tool. The target gloss range Rs can also be obtained from standards such as EN10169:2013.

[0131] In the second step 120 of the gloss control method, gloss measurement data G of the organic coating is collected at least in a width section downstream of the electron beam curing device.

[0132] Preferably, wet film temperature T measurement data is also collected over at least a portion of the moving strip width downstream of the cooling module and upstream of the ultraviolet curing device. More preferably, the temperature is measured using a wet film temperature measuring device as described above, and the gloss measurement is performed using a gloss measuring device as described above.

[0133] It is preferable that the measurement be taken at intervals short enough to ensure proper gloss control. Examples of time intervals include: less than 30 s, less than 20 s, less than every 10 s, less than every 5 s, less than every 2 s, and less than every second. It is more preferable that the measurement be substantially continuous or uninterrupted. It is preferable that the measurements be collected at intervals short enough to ensure proper gloss control. Examples of intervals include: less than every 10 s, less than every 5 s, less than every 2 s, and less than every second. It is more preferable that the measurements be collected substantially continuously or uninterrupted. It is preferable that the measurements be collected in the gloss control tool, in particular in the data collection module, and even more preferably automatically using an appropriate interface.

[0134] By "a section of width," it is meant that the moving band is conceptually divided into sections adjacent to each other across the width of the band. This may be a single width section or multiple sections. Consequently, the wet film and organic coating may also be conceptually divided into similar width sections. By "at least a section of width," it is meant that the method is implemented either over a single width section, or over multiple width sections, or over the entire width of the moving band. If the method is not implemented over the entire width, the following can be measured and collected:

[0135] - the gloss G of an organic coating in one single width section, if the measurement in that width section is considered significant enough to control the gloss over the entire width of the strip, or

[0136] - Organic coating gloss in multiple width sections, so that the gloss in each width section can be controlled independently from other sections.

[0137] Similarly, it is not necessary, it is possible to measure and collect:

[0138] - the wet film temperature T over one single width section, if the measurement over that width section is considered sufficiently representative of the average temperature over the entire width of the strip, or

[0139] - wet film temperature in multiple width sections, so that the temperature in each width section can be adjusted independently from other sections.

[0140] In one embodiment, the data collection step is performed after the installation step.

[0141] In another embodiment, particularly during continuous operation of the coil coating line, the data collection step can be performed in parallel with the setup step. In the case of continuous operation, since the strip consists of various coils attached end-to-end, changes in the strip properties and its technical characteristics frequently occur. While the data collection step is in progress, any of the specified parameters may need to be changed for any reason, in particular any parameter within the specified gloss value Gs and / or specified gloss range Rs, for example, due to a change in the specified gloss or a change in the radiation-cured paint. The setup step then proceeds.

[0142] Preferably, in this second step 120 of the gloss control method, the PW power data of the cooling module is also collected.

[0143] In the third step 130 of the gloss control method, a possible deviation of the measured gloss G beyond the specified range Rs is corrected. First, the possible gloss deviation is estimated by comparing the measured gloss G with the specified gloss value Gs and / or the specified gloss range Rs. If the measured gloss G is still within the specified gloss range Rs, the adjustment is saved. If the measured gloss G is outside the specified gloss range Rs, the correction C Р , applied to the cooling module power, is calculated taking into account the Gs values ​​and the measured glare G using a feedback controller.

[0144] Gloss deviation assessment can be performed at any time. It is preferable to conduct the assessment at sufficiently short time intervals to ensure proper gloss control. Examples of time intervals: less than 30 s, less than 20 s, less than 10 s, less than 5 s, less than 2 s, less than every second. It is more preferable for the assessment to be performed almost continuously or continuously.

[0145] Calculating the C correction Р, applied to the power of the cooling module, is performed using a feedback controller. Preferably, this controller is a proportional-integral-derivative controller. Since in some cases only one or two elements of the controller can provide adequate control, some parameters of the controller can be set to zero to deactivate some elements. In particular, at least one element of the integral element and the differential element of the proportional-integral-derivative controller is active. By "active" is meant that the element is not set to zero / is used for calculation. In other words, the proportional-integral-derivative controller is preferably a PI controller, a PD controller, an I controller, a D controller, or a PID controller.

[0146] Accordingly, it can calculate the C correction to a large extent Рaccording to the equation with the general formula:

[0147]

[0148] or

[0149]

[0150] where e is the error, i.e., the difference between the desired setpoint and the measured process variable, t is time or an instantaneous point in time, and τ is the integration variable. Other control functions are well known to those skilled in the art and can be used to control the gloss of organic coatings.

[0151] In the first version of calculating the C correction Р The feedback controller is based directly on the gloss of the organic coating. In other words, the measured process variable is the measured gloss, and the setpoint is Gs. In this case, the correction C Р is a function of the difference between the Gs value and the measured brightness G.

[0152] In particular, Amendment C Р, applied to the power of the cooling module, can be calculated using equation 1:

[0153] (1)

[0154] where Kp is the proportional gain, Ki is the integral gain, Kd is the differential gain, and e1 is the difference between Gs and the measured luminosity G.

[0155] In particular, Ki > 0 and / or Kd > 0.

[0156] Good practice rules for the initial selection of Kp, Ki, and Kd and their adjustment are well known to those skilled in the art. Therefore, Kp, Ki, and Kd can be easily selected and adjusted as needed. The initial gain factors Kp, Ki, and Kd can be manually entered into the gloss management tool, particularly in the setup module. They can be set during the setup phase.

[0157] Alternatively, Amendment C Р , applied to the power of the heating module, can be calculated using the following formula:

[0158]

[0159] where Kp is the proportional gain, Ti is the integral time, Td is the differential time, and e1 is the difference between Gs and the measured brightness G.

[0160] In particular, 1 / Ti > 0 and / or Td > 0.

[0161] Good practice rules for the initial selection and adjustment of Kp, Ti, and Td are well known to those skilled in the art. Therefore, Kp, Ti, and Td can be easily selected and adjusted as needed. The initial parameters Kp, Ti, and Td can be manually entered into the gloss management tool, particularly in the setup module. They can be set during the setup phase.

[0162] In the second embodiment, where the data collection step also includes collecting data on the temperature T of the wet film at least in a section of the width of the moving strip downstream of the cooling module and upstream of the UV curing device, since it has been noticed that there is a relationship between the temperature of the wet film before UV curing and the gloss of the organic coating after electron beam curing, the feedback control of the power of the cooling module is based on the temperature of the wet film at least in a section of the width downstream of the cooling module and upstream of the UV curing device.In other words, the measured process variable is the measured temperature, and the desired setpoint is the adjusted temperature Tc that the wet film must reach in at least the width portion downstream of the cooling module and upstream of the UV curing device in order to achieve the set gloss value Gs.

[0163] Accordingly, in the first sub-step of the correction step, a corrected temperature Tc is calculated that the wet film must reach at least in the width section downstream of the cooling module and upstream of the UV curing device.

[0164] In general, the corrected temperature Tc is calculated according to equation 2:

[0165] Tc = f1(T, G, Gs) (2)

[0166] where function f1 is a predetermined mathematical relationship between the wet-film temperature before UV curing and the gloss of the organic coating after electron beam curing. "Predetermined" means that a calibration step, preferably as described below, was performed on the coil coating line before the method was implemented.

[0167] The function f1 can be obtained in a calibration step performed before the installation step. In this calibration step, wet radiation-curable paint films to be used on the coil coating line are heated at different temperatures, cured using a dual-curing process under standard conditions, and then the gloss of the organic coatings is measured. In this way, the function f1 can be derived. This calibration step can be performed once and for all and does not need to be repeated each time the method according to the invention is implemented. The function f1 can be manually entered into the gloss management tool, in particular, into the installation module. Alternatively, it can be obtained automatically by comparing predefined mathematical relationships entered into the gloss management tool, possibly in the form of a table, with the paint standard from the coil coating line order book, in particular from the planning tool.The f1 function can be set during installation.

[0168] In particular, it was observed that for some commercially available radiation curing paints for steel coil coating line, there is a linear mathematical relationship between the wet film temperature before ultraviolet curing and the gloss of the organic coating after electron beam curing, which is expressed by the following equation:

[0169] T = T0- KG

[0170] where K is the proportionality coefficient.

[0171] In this case, the corrected temperature Tc is calculated according to equation 3:

[0172] Tc = T + K (G - Gs) (3)

[0173] The proportionality factor K can be obtained during a calibration step performed before the installation step. During this calibration step, wet radiation-curable paint films to be used on the coil coating line are heated to various temperatures, cured using a dual-curing process under standard curing conditions, and then the gloss of the organic coatings is measured. This allows the proportionality factor K to be derived. It is preferably expressed in °C / GU, °F / GU, or K / GU, depending on the temperature unit. This calibration step can be performed once and for all and does not need to be repeated each time the method according to the invention is implemented.

[0174] In practical terms, during the correction step, the proportionality coefficient K is determined from a predetermined linear mathematical relationship between the wet-film temperature before UV curing and the gloss of the organic coating after electron beam curing. This predetermined linear mathematical relationship is accessible to the coil coating line operator. By "predetermined" is meant that a calibration step, preferably as described above, has been performed prior to implementing the method on the coil coating line. The proportionality coefficient K can be manually entered into the gloss control tool, particularly in the installation module.Alternatively, it can be obtained automatically by matching pre-defined linear mathematical relationships entered into the gloss management tool, perhaps in the form of a table, with a paint reference from the coil coating line order book, in particular from a planning tool.

[0175] For example, it has been observed that for some commercially available radiation curing paints for coating steel, K is usually in the range of 0.3 to 1.2. More generally, K > 0.

[0176] After calculating the corrected temperature Tc, the correction correction C P , applied to the power of the cooling module, is calculated as a function of the difference between Tc and the measured temperature T.

[0177] In particular, in the case of a proportional-integral-differential controller in parallel form, the correction correction C P can be calculated using equation 4:

[0178] (4)

[0179] where K'p is the proportional gain, K'i is the integral gain, K'd is the differential gain, and e2 is the difference between Tc and the measured temperature T.

[0180] In particular, K'i > 0 and / or K'd > 0.

[0181] Good practice rules for the initial selection and adjustment of the Kp, Ki, and Kd gain coefficients are well known to those skilled in the art. Therefore, Kp, Ki, and Kd can be easily selected and adjusted as needed. The initial gain coefficients Kp, Ki, and Kd can be manually entered into the gloss management tool, particularly in the setup module. They can be set during the setup phase.

[0182] Alternatively, in the case of a standard form proportional-integral-derivative controller, Amendment C P , applied to the power of the cooling module, can be calculated using the following formula:

[0183]

[0184] where K'p is the proportional gain, T'i is the integral time, T'd is the differential time, and e2 is the difference between Tc and the measured temperature T.

[0185] In particular, 1 / T'i > 0 and / or T'd > 0.

[0186] Good practice rules for the initial selection and adjustment of the coefficients K'p, T'i, and T'd are well known to those skilled in the art. Therefore, K'p, T'i, and T'd can be easily selected and adjusted as needed. The initial parameters K'p, T'i, and T'd can be manually entered into the gloss management tool, particularly in the setup module. They can be set during the setup phase.

[0187] This is the second option for calculating the correction amendment C Pis very convenient because it avoids the overlap of interdependent feedback control and controls that the wet film temperature does not fall below the minimum temperature Tmin, which will prevent the radiation-cured paint from reacting when exposed to UV light, as will be described in detail later.

[0188] After calculating the C correction P , applied to the power of the cooling module, the line installation is adjusted taking into account the correction C P , in order to thus correct the deviation of the measured gloss.

[0189] Specifically, after calculating the Cp correction, the cooling module power is adjusted using the Cp correction correction. Adjusting the cooling module power includes setting the cooling module on and off. By adjusting the cooling module, the wet film temperature in the width section downstream of the cooling module and upstream of the UV curing unit is corrected, and the Gs gloss value on the organic coating in the width section downstream of the electron beam curing unit is achieved. Cooling module power adjustment can be performed either manually by the operator or automatically using the gloss control tool, specifically the correction module.

[0190] Alternatively, if the coil coating line is equipped with a heating device comprising a heating module and located adjacent to a cooling device, after calculating the correction correction Cp, the heating module is turned on and its power is adjusted so that the gloss on the organic coating reaches the Gs value at least in the section of the width of the moving strip downstream of the electron beam curing device. If the corrected temperature Tc is obtained before calculating the correction correction Cp, the power of the heating module is adjusted so that the wet film reaches the corrected temperature Tc at least in the section of the width of the moving strip downstream of the cooling / heating module and upstream of the ultraviolet curing device.This alternative gloss adjustment method is particularly useful when the cooling module is already running at minimum power or is turned off, and the wet film temperature upstream of the UV curing unit needs to be further increased.

[0191] Alternatively, if the coil coating line is equipped with an inductor upstream of the paint applicator, after calculating the correction correction Cp, the power of the inductor is adjusted such that the strip temperature at the level of the paint applicator is adjusted such that the gloss on the organic coating reaches the Gs value at least over a section of the moving strip width downstream of the electron beam curing device. If the corrected temperature Tc was calculated before calculating the correction correction Cp, the power of the inductor is adjusted such that the wet film reaches the corrected temperature Tc at least over a section of the moving strip width downstream of the cooling / heating module and upstream of the ultraviolet curing device.This alternative gloss adjustment method is particularly useful when the cooling module is already running at minimum power or is turned off, and the wet film temperature upstream of the UV curing unit needs to be further increased.

[0192] In one embodiment, the adjusting step 130 is performed after the data collection step 120.

[0193] In another embodiment, particularly in continuous operation of a coil coating line, the correction step can be performed in parallel with the data collection step. In such continuous operation, since the strip consists of various coils joined end-to-end, changes in the strip properties and its technical characteristics frequently occur. This can lead to deviations in gloss characteristics. During the data collection step, a correction step is performed to correct the measured gloss.

[0194] Optionally, the method further comprises step 110, in which the initial conditions of the line are set. This step is called the initial line setup step. As explained above, the method consists in that any deviation of the measured gloss outside the specified gloss range Rs is corrected. However, at the beginning of a production campaign on a coil coating line or after a significant change, for example, in the strip format, paint layer thickness, paint color, or line speed, the line conditions may be changed relative to the conditions necessary to achieve the specified gloss value Gs. In this case, the cooling module may not provide the necessary cooling and / or it may take some time to reach the power corresponding to the correction correction Cp and / or it may not be powerful enough to achieve the corrected wet film temperature Tc.Consequently, part of the coated strip may be rejected because the gloss does not meet specifications. Furthermore, the UV dose to which the wet film must be exposed to form a surface roughness sufficient to achieve the specified gloss value may be inappropriate. In this case, the cooling module must compensate for the shift in UV dose, possibly through intensive cooling, which takes time. In this case, again, part of the coated strip may be rejected because the gloss does not meet specifications. To minimize the length of the coated strip that does not meet specifications, it is advisable to set initial conditions for the line.

[0195] For this purpose, several process parameters and / or characteristics of the coated strip are collected in the first sub-step. An example of a process parameter is the initial line speed LS0. It preferably corresponds to the recommended speed for the next coil to be coated on the coil coating line. Another example is the initial film thickness FTh0 of the wet film applied to the strip by the paint applicator. The initial film thickness preferably corresponds to the organic coating thickness specified for the next coil to be coated on the coil coating line. Another example is the temperature of the moving strip upstream of the paint applicator, preferably upstream of the inductor. Examples of characteristics are the initial strip thickness STh0, the initial strip width SWd0, and the paint color.Preferably, data on the initial line speed LS, initial film thickness FT, initial strip thickness ST, initial strip width SWd, and paint color are collected. From a practical standpoint, the process parameters and / or characteristics can be manually entered in the gloss management tool, in particular, in the setup module. Alternatively, they can be automatically retrieved from the coil coating line order book, in particular, from the planning tool, and / or can be derived from the order book. For example, the initial film thickness FT can be derived from the organic coating thickness specified in the order book.

[0196] After collecting the process parameters and / or characteristics, the second sub-step involves setting the initial line conditions based on the collected process parameters and / or characteristics. Specifically, these initial line conditions are calculated based on the collected process parameters and / or characteristics. The following initial line conditions can be set:

[0197] - initial power PW0 of the cooling module;

[0198] - initial dose D0UV of the UV curing device or UV module, if used;

[0199] - the initial distance L0 between the UV curing device or UV module, if used, and the electron beam curing device.

[0200] The initial power PW0 can be set based on the mass flow of the moving strip, the strip's specific heat capacity, and the cooling efficiency. The initial UV dose D0 can be set based on the data obtained during the calibration step performed before the initial line setup. The initial distance L0 can be set based on the data obtained during the calibration step performed before the initial line setup.

[0201] From a practical standpoint, the initial line conditions can be manually entered into the coil coating line management tool. Alternatively, they can be automatically entered by the gloss control tool in the coil coating line management tool.

[0202] In one embodiment, the initial line setup step 110 is performed before the setup step 100. This allows production to begin with line conditions already optimized for the first roll of the production campaign, as well as with a specified combination of gloss Gs values ​​and gloss Rs range. During production, a data collection step and an adjustment step can be performed to control the gloss. If for any reason it is necessary to change any of the specified parameters, in particular any value from the specified gloss Gs value and / or the specified gloss Rs range, for example, when changing the specified gloss value or when changing the radiation-cured paint, then it is necessary to rely on the effectiveness of the data collection step 120 and the adjustment step 130 to maintain the measured gloss within the specified gloss Rs range.

[0203] In another embodiment, the initial line setup step 110 is performed after the setup step 100, as illustrated in Fig. 2. In this way, the initial line conditions can be set taking into account the specified gloss value Gs. As a result, the line conditions are better optimized for the first roll of a production campaign. In addition, during the production process, if for any reason it is necessary to change any of the specified parameters, in particular the specified gloss value Gs and / or the specified gloss range Rs, the initial line settings can be reset, which helps minimize the transition period.

[0204] In another embodiment, the initial line setup step 110 is performed before and after the setup step 100 in order to utilize the advantages of both embodiments described above.

[0205] In another embodiment, particularly during continuous operation of a coil coating line, the initial setup phase can be performed in parallel with the data collection phase. In continuous operation, since the strip consists of various coils joined end-to-end, changes in strip properties and technical characteristics frequently occur. Re-initializing the line conditions when one of these changes occurs helps achieve the specified gloss value as quickly as possible.

[0206] The second embodiment of the method is described below with reference to FIG. 3.

[0207] This embodiment differs from the first one mainly in that the adjusting step includes additional sub-steps for:

[0208] - ensuring that the temperature of the wet film upstream of the UV curing device does not fall below the minimum temperature Tmin, which would lead to diffusion blockage and / or mobility phenomena, and

[0209] - the corresponding correction of the deviation of the measured gloss G.

[0210] This configuration better ensures that the wet film will react correctly to UV radiation.

[0211] The details given in the description of the first embodiment of the invention also apply to the second embodiment. Additional steps and corresponding features are described in detail below.

[0212] Step 100 of the setup process additionally includes setting the minimum temperature Tmin for the radiation-curable paint. This temperature may be recommended by the paint supplier. Alternatively, it can be determined during the calibration step performed before the setup process. During this calibration step, wet films of radiation-curable paint intended for use on a coil coating line are cooled at various temperatures, cured using a dual-cure process under standard conditions, and then the gloss of the organic coatings is measured. The temperature at which the wet film does not react to UV radiation can be set as Tmin. For practical purposes, the minimum temperature Tmin can be manually entered in the gloss management tool, specifically in the setup module.Alternatively, it can be obtained automatically by comparing the various minimum temperatures entered in the gloss management tool with the paint reference value from the coil coating line order book, in particular from the planning tool.

[0213] The data collection step 120 includes collecting data on the wet film temperature T at least in a section of the width of the moving strip downstream of the cooling module and upstream of the ultraviolet curing device.

[0214] Step 120 of data collection further includes collecting data on the UV dose D of the UV module. The UV module power is typically known to the operator, possibly from the control instrument of the roll coating line, but for a given power, the actual UV dose applied to the wet film varies with the line speed LS. Accordingly, the UV dose is calculated based on the UV module power and the line speed, and data collection is performed. The line speed itself is typically known to the operator, possibly from the control instrument of the roll coating line.

[0215] It is preferable for the UV dose to be recalculated and collected each time the UV module power and / or line speed are adjusted. It is even more preferable for UV dose data collection to be nearly continuous. It is preferable for the UV dose to be collected in the gloss management tool, specifically in the data collection module, and preferably automatically via an appropriate interface.

[0216] In the correction step 130, if the corrected temperature Tc is calculated before the correction correction Cp is calculated, it is compared with the minimum temperature Tmin. Otherwise, the correction step may include a sub-step of calculating the corrected temperature Tc that the wet film must reach at least in the width section downstream of the cooling module and upstream of the UV curing device. This sub-step may be performed after the correction correction Cp is calculated or at any other suitable time. After performing this sub-step, the temperature Tc may be compared with the minimum temperature Tmin. Alternatively, the temperature T may be compared with the minimum temperature Tmin.

[0217] If Tc (or T) exceeds Tmin, the power of the cooling module is adjusted as described in detail in the first embodiment.

[0218] If Tc (or T) is less than Tmin, then the gloss must be adjusted without further increasing the cooling module power. One method is adjustment, specifically reducing the UV module power. Indeed, it has been observed that this affects the gloss of the organic coating. The more the UV dose applied to the wet film is reduced, the more the gloss increases. Therefore, adjustment step 130 additionally includes calculating the correction factor C. D , applied to the UV dose to which the wet film is to be exposed over at least a portion of the width of the moving strip in the UV module, according to equation 5:

[0219] C D = f2(G, Gs) (5)

[0220] Equation (5) can be obtained in a calibration step performed before the adjustment step, preferably before the setup step. In this calibration step, wet films of radiation-curable paint to be used on a coil coating line are exposed to various doses of UV radiation and also cured using electron beam irradiation under standard conditions, and then the gloss of the organic coating is measured. Thus, the function f2 can be derived for each radiation-curable paint. This calibration step can be performed once and for all and does not require re-execution with each implementation of the method according to the invention. Alternatively, the function f2 can be a PID function of the difference between the gloss value Gs and the measured gloss G.

[0221] Preferably, function f2 of the predetermined mathematical relationship between the UV dose to which the wet film of the radiation-cured paint is exposed and the gloss of the organic coating after electron beam curing is defined at the setup stage. By "predetermined" is meant that a calibration step, preferably as described above, was performed before implementing the method on the coil coating line. Function f2 can be manually entered into the gloss management tool, in particular, in the setup module. Alternatively, it can be obtained automatically by comparing the predetermined mathematical relationships entered into the gloss management tool with the paint master from the coil coating line order book, in particular, from the scheduling tool.

[0222] For example, it has been observed that for commercially available radiation curable paints for steel coil coating lines, the f2 function typically follows a gloss curve that decreases to an asymptote as the UV dose increases.

[0223] After calculating the C correction D , applied to the UV radiation dose, the line setting parameter is adjusted, which is not the power of the cooling module, which is not the power of the heating module, if used, and which is not the power of the inductor, if used, taking into account the calculated correction C D to correct for the deviation in measured gloss.

[0224] In the embodiment illustrated in Fig. 3, after calculating the correction C D , applied to the UV dose, the power of the UV module is adjusted, in particular, it is reduced in such a way that the wet film at least in the section of the width of the moving strip is exposed to the dose Dc = D + C DUV radiation in the UV module. By adjusting the UV module, the UV dose to which the wet film is exposed is adjusted within the UV module's width, achieving the Gs gloss value on the organic coating within the width downstream of the electron beam curing unit. UV module power can be adjusted either manually by the operator or automatically using the gloss control tool.

[0225] The third embodiment of the method is further described with reference to Fig. 4.

[0226] This embodiment differs from the second one in that the correction step includes additional sub-steps for:

[0227] - ensuring that the UV dose is not lower than the minimum UV dose Dmin to which the wet film may be exposed,

[0228] - the corresponding correction of the deviation of the measured gloss G.

[0229] With this configuration, the method further prevents insufficient curing of the wet film in the UV curing device, which may adversely affect the gloss.

[0230] The details given in the description of the first and second embodiments also apply to the third embodiment. Additional steps and corresponding features are described in detail below.

[0231] In this embodiment, the UV module of the ultraviolet curing device of the coil coating line is movable along the path P. Accordingly, the distance L between the UV module and the electron beam curing device can be adjusted.

[0232] Setup step 100 further includes setting the minimum UV dose Dmin to which the wet film may be exposed in the UV module. This UV dose may be recommended by the paint supplier. Alternatively, it may be determined by the coil coating line operator, particularly during the calibration stage. In practical terms, the minimum UV dose Dmin can be manually entered into the gloss management tool, particularly in the setup module. Alternatively, it can be obtained automatically by comparing various minimum UV doses entered in the gloss management tool with a paint reference value from the coil coating line order book, particularly from the scheduling tool.

[0233] Step 120 of data collection further includes collecting data on the distance L between the UV module and the electron beam curing device. This distance is typically known to the operator, possibly from the coil coating line control tool. The data can be collected manually. Preferably, the data should be collected in the gloss control tool, or even more preferably, automatically, using an appropriate interface. Preferably, the data should only be collected when the distance L changes.

[0234] When performing step 130 of correction, after calculating the correction C D applied to a dose of UV radiation, the sum D + C D(hereinafter defined as Dc) is compared with the minimum UV dose Dmin. If Dc exceeds Dmin, the power / setting of the UV module is adjusted such that the wet film is exposed to the UV dose Dc in the UV module at least over a section of the moving strip width. By adjusting the UV module, the UV dose applied to the wet film over a section of the UV module width is adjusted, and a gloss of the same value Gs as in the second embodiment is achieved on the organic coating over a section of the width downstream of the electron beam curing device.

[0235] If Dc is less than Dmin, then the gloss must be adjusted without further reducing the UV dose of the UV module. One method is adjustment, specifically reducing the distance between the UV module and the electron beam curing device. Indeed, this has been observed to affect the gloss of the organic coating. The shorter the time between UV curing and electron beam curing, the higher the gloss. Therefore, correction step 130 additionally includes calculating the correction factor C. L , applied to the distance L between the UV module and the electron beam curing device, according to equation 6:

[0236] C L = f3(G, Gs) (6)

[0237] Equation (6) can be obtained in a calibration step performed before the adjustment step, preferably before the setting step. During this calibration step, wet films of radiation-curable paint intended for use on a coil coating line are sequentially exposed to UV irradiation and electron beam curing under standard curing conditions with different times between the two curing processes, after which the gloss of the organic coating is measured. In this way, the function f3 can be derived for each radiation-curable paint sample. This calibration step can be performed once and for all and does not require re-execution with each implementation of the method according to the invention. Alternatively, the function f3 can be a PID function of the difference between Gs and the measured gloss G.

[0238] It is preferable that function f3 of the preset mathematical relationship between the distance between the UV module and the electron beam curing device and the gloss of the organic coating after electron beam curing be set at the setup stage. By "preset" is meant that a calibration step, preferably as described above, was performed before implementing the method on the coil coating line. Function f3 can be manually entered into the gloss management tool, particularly in the setup module. Alternatively, it can be obtained automatically by comparing the preset mathematical relationships entered into the gloss management tool with the paint master from the coil coating line order book, particularly from the planning tool.

[0239] For example, it has been observed that for commercially available radiation-curable paints for coating rolled steel, the f3 function typically follows a light curve that decreases to an asymptote as L increases.

[0240] After calculating the C correction L , applied to the distance between the UV module and the electron beam curing device, the line setting parameter is adjusted, which is not the power of the cooling module, which is not the power of the heating module, if used, which is not the power of the inductor, if used, and which is not the power of the UV module, taking into account the calculated correction C L to correct for the deviation in measured gloss.

[0241] In the embodiment illustrated in Fig. 4, after calculating the correction C L , the distance between the UV module and the electron beam curing device is adjusted, in particular, it is reduced to the adjusted distance Lc = L + C LTo achieve a gloss Gs on the organic coating over at least a portion of the moving strip width downstream of the electron beam curing device. Distance adjustment can be performed manually by the operator or automatically using a gloss control tool.

[0242] Alternatively, especially if the distance between the UV module and the electron beam curing unit cannot be further increased or decreased, the line speed can be adjusted. In this case, the initial line setup can be repeated to adjust the new line speed, the initial power PW0 of the heating module, the initial UV dose D0 of the UV curing unit, and the initial distance L0 between the UV curing unit and the electron beam curing unit.

[0243] The invention also relates to a method for forming an organic coating on a moving strip on a coil coating line comprising, sequentially arranged along the path P of the moving strip: a device for applying paint, a cooling device containing a cooling module, an ultraviolet curing device and an electron beam curing device; the method includes the following steps:

[0244] - applying a wet film of radiation-cured paint to a moving strip using a paint application device,

[0245] - cooling of wet paint film with radiation curing in the cooling module,

[0246] - the effect of UV radiation on wet film of radiation-cured paint in an ultraviolet curing device,

[0247] - Wet paint film curing with radiation curing in an electron beam device to form an organic coating,

[0248] The gloss of the organic coating is controlled as follows:

[0249] - set the specified value Gs of organic coating gloss and the specified range Rs of organic coating gloss;

[0250] - collecting gloss measurement data G of the organic coating at least in a width section downstream of the electron beam curing device,

[0251] - corrects the deviation of the measured brightness G from the specified brightness range Rs, and this correction stage includes the sub-stage of calculating the correction C P , applied to the power of the cooling module, taking into account the value of Gs and the measured gloss G, using a feedback controller, as well as a sub-stage of adjusting the setting parameter of the rolling coating line taking into account the calculated correction C P .

[0252] All the details provided regarding the gloss control method and the details provided regarding the coil coating line also apply to the organic coating formation method.

[0253] The invention also relates to a method for producing pre-painted metal containing a metal strip and an organic coating on a coil coating line comprising, sequentially arranged along the path P of a moving metal strip: a paint application device, a cooling device containing a cooling module, an ultraviolet curing device and an electron beam curing device; the method includes the following steps:

[0254] - applying a wet film of radiation-cured paint to a moving metal strip using a paint application device,

[0255] - cooling of wet paint film with radiation curing in the cooling module,

[0256] - the effect of UV radiation on wet film of radiation-cured paint in an ultraviolet curing device,

[0257] - Wet paint film curing with radiation curing in an electron beam device to form an organic coating,

[0258] The gloss of the organic coating is controlled as follows:

[0259] - set the specified value Gs of organic coating gloss and the specified range Rs of organic coating gloss,

[0260] - collecting gloss measurement data G of the organic coating at least in a width section downstream of the electron beam curing device,

[0261] - correct the deviation of the measured brightness G beyond the specified brightness range Rs, while this correction step includes the sub-step of calculating the correction C P, applied to the power of the cooling module, taking into account the value of the gloss Gs and the measured gloss G, using a feedback controller, as well as a sub-stage of adjusting the setting parameter of the coating line of the rolled product taking into account the calculated correction C P .

[0262] Optional, the metal strip can be heated before applying the radiation cured wet film paint.

[0263] All the details provided regarding the gloss control method and all the details provided regarding the coil coating line refer to the production method of pre-painted metal.

Claims

1. A method for controlling the gloss of an organic coating formed by applying and curing a wet film of radiation-curable paint on a moving strip on a coil coating line comprising, sequentially arranged along a path P of the moving strip: a paint application device, a cooling device containing a cooling module, an ultraviolet curing device and an electron beam curing device, comprising the steps of: - set the specified value Gs of the gloss of the organic coating and the specified range Rs of the gloss of the organic coating, - collecting gloss measurement data G of the organic coating at least over a width section downstream of the electron beam curing device; - the deviation of the measured brightness G beyond the specified brightness range Rs is corrected; moreover, at this stage of the correction, a sub-stage is performed in which the correction C is calculated P, applied to the power of the cooling module, taking into account the value of the gloss Gs and the measured gloss G, using a feedback controller, and a sub-stage in which the setting parameter of the coating line of the rolled product is adjusted taking into account the calculated correction C P .

2. The method according to claim 1, wherein the feedback controller is a proportional-integral-differential controller.

3. The method according to paragraph 1 or 2, in which amendment C P is a function of the difference between Gs and the measured brightness G.

4. The method according to any one of paragraphs 1-3, in which amendment C P , applied to the power of the cooling module, is calculated in accordance with equation 1: (1) where Kp is the proportional gain, Ki is the integral gain, Kd is the differential gain, and e1 is the difference between Gs and the measured brightness G.

5. The method according to claim 1 or 2, in which, at the data collection step, data on the temperature T of the wet film is also collected at least over a section of the width of the moving strip downstream of the cooling module and upstream of the ultraviolet curing device, and at the correction step, a sub-step is also performed in which a corrected temperature Tc is calculated, which the wet film must reach at least over a section of the width downstream of the cooling module and upstream of the ultraviolet curing device.

6. The method according to claim 5, wherein the corrected temperature Tc is calculated in accordance with equation 2: Tc = f1(T, G, Gs) (2) where f1 is a function of a predetermined mathematical relationship between the wet film temperature before UV curing and the gloss of the organic coating after electron beam curing.

7. The method according to claim 5, wherein the corrected temperature Tc is calculated in accordance with equation 3: Tc = T + K (G – Gs) (3) 8. The method according to any one of paragraphs 5-7, in which amendment C P is a function of the difference between Tc and the measured temperature T.

9. The method according to any one of paragraphs 5-7, in which amendment C P , applied to the power of the cooling module, is calculated in accordance with equation 4: (4) where K'p is the proportional gain, K'i is the integral gain, K'd is the differential gain, and e2 is the difference between Tc and the measured temperature T.

10. The method according to any one of paragraphs 1-9, in which at the sub-stage of adjusting the setting parameter of the rolled metal coating line, the power of the cooling module is adjusted using the correction amendment C P .

11. The method according to any one of paragraphs 5-9, in which: - the ultraviolet curing device contains a UV module, - at the installation stage, the minimum temperature Tmin is additionally set for radiation-cured paint, - at the data collection stage, additional data on the UV radiation dose D of the UV module is collected, - at the sub-stage of adjusting the setting parameter of the rolled metal coating line: evaluate whether the value of Tc is less than the value of Tmin, If not, adjust the cooling module power using correction C P , if Tc is less than Tmin: calculate the correction C D , applied to the UV dose to which the wet film must be exposed over at least the width portion in the UV module, according to equation 5: C D = f2(G, Gs) (5) adjust the installation parameter of the rolled metal coating line, which is not the power of the cooling module, taking into account the calculated correction C D .

12. The method according to claim 11, in which, at the sub-step of adjusting the setting parameter of the coil coating line, which is not the power of the cooling module, the power of the UV module is adjusted in such a way that the wet film at least in a section of the width of the moving strip is exposed to the adjusted dose Dc = D + C D UV radiation.

13. The method according to paragraph 11, in which - The UV module is movable along the path P, - at the installation stage, the minimum dose Dmin of UV radiation to which the wet film in the UV module can be exposed is additionally set, - at the data collection stage, additional data is collected on the distance L between the UV module and the electron beam curing device, - at the sub-stage of adjusting the setting parameter of the rolled metal coating line, which is not the capacity of the cooling module: evaluate whether the value of D + C D less than the value of Dmin, if not, adjust the power of the UV module so that the wet film, at least over a section of the width of the moving strip, is exposed to an adjusted dose of UV radiation Dc = D + C D , if the value is D + C D less than the Dmin value: calculate the correction C L , applied to the distance between the UV module and the electron beam curing device, according to equation 6: C L = f3(G, G s ) (6) adjust the installation parameter of the rolled metal coating line, which is not the power of the cooling module and the power of the UV module, taking into account the calculated correction C L .

14. The method according to claim 13, in which, at the sub-step of adjusting the setting parameter of the rolled metal coating line, which is not the power of the cooling module and the power of the UV module, the distance between the UV module and the electron beam curing device is adjusted to the adjusted distance Lc = L + C L in such a way that the gloss value Gs is achieved on the organic coating, at least in a section of the width of the moving strip downstream of the electron beam curing device.

15. A coil coating line comprising a sequentially arranged device for applying paint, a cooling device comprising a cooling module, an ultraviolet curing device and an electron beam curing device, wherein the coil coating line also comprises a gloss control tool for controlling the gloss of an organic coating formed by applying and curing a wet film of radiation-curable paint on a moving strip on the coil coating line, wherein the gloss control tool comprises: - a setting module configured to set a given value Gs of the gloss of the organic coating and a given range Rs of the gloss of the organic coating; - a data collection module configured to collect data on the measurement of the gloss G of the organic coating at least in a width section downstream of the electron beam curing device; - a correction module configured to correct the deviation of the measured brightness G beyond the specified brightness range Rs, wherein the correction includes a sub-step of calculating the correction correction C P , applied to the power of the cooling module, taking into account the value of Gs and the measured gloss G, using a feedback controller, as well as a sub-stage of adjusting the installation parameter of the roll coating line taking into account the calculated correction amendment Cp.

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