In-line web material processing apparatus and method for producing a coated material

Abstract

An in-line web material processing method and apparatus for vacuum coating of a web material in the form of paper or paperboard is disclosed. The method includes receiving web material through an inlet opening in an auxiliary vacuum chamber from ambient pressure, guiding it from the inlet opening to a transit opening through an inlet guide path, and receiving it in a process vacuum chamber through the transit opening. The method further includes coating the web material in the process vacuum chamber, receiving the coated material in the auxiliary vacuum chamber through the transit opening, guiding the coated material from the transit opening to an outlet opening through an outlet guide path. The inlet guide path and the outlet guide path are separate from each other and are over at least a part of their extensions separated by a separation distance of less than half a width of the web material.

Description

[0001] IN-LINE WEB MATERIAL PROCESSING APPARATUS AND METHOD FOR PRODUCING A COATED MATERIAL

[0002] TECHNICAL FIELD OF THE INVENTION

[0003] The present invention relates to an in-line web material processing apparatus for producing a coated material, wherein the web material is paper or paperboard, as well as to a method for vacuum coating of such a web material.

[0004] BACKGROUND OF THE INVENTION

[0005] Coated web materials, such as coated paper or paperboard, are used for example as packaging materials. The coating may e.g. serve as a barrier against moisture, water, oxygen, and the like. Such coated web materials are e.g. used as packaging materials for food, pharmaceuticals, electronic devices, and other types of products containing liquid or gas, or packed products being sensitive to moisture, water, oxygen or the like. Such a coating is often used in combination with other layers, such as one or more polymer layers.

[0006] For more demanding barrier requirements, the barrier coating layer may e.g. be provided by vacuum coating, such as metallization, in a vacuum coating unit. It is per se known to form such vacuum coatings onto a web material in an in-line process, such as a roll- to-roll process. Such vacuum coating processes are e.g. disclosed in WO 2022 / 090337 and US 2020 / 0165721. In these known systems, a vacuum chamber is provided in which a supply roll of web material is arranged, as well as a vacuum coating unit and a rewinding roll.

[0007] However, known vacuum coating processes are not well suited for applying coatings on thicker web materials, such as paperboard. Thicker web materials often contain more moisture, which makes evacuation of the vacuum chamber to obtain an adequate low pressure tedious. An option would be to use more efficient vacuum pumps, but this would lead to increased costs and may still not address problems such as long run time, e.g. due to long degassing time, and low throughput. Further, supply rolls of thicker web materials generally contain much lower lengths of web material than supply rolls of thinner web materials, which means that the supply roll needs to be replaced much more frequently. Overall, this makes coating of thicker web materials in this way tedious, cumbersome and expensive.

[0008] The solution to this problem has been to provide the vacuum deposited barrier coating or layer on a thin film or web material, such as paper or polymer film, and to laminate this onto the thicker web material. Hereby, the thicker web material need not be provided in vacuum, since the lamination can take place at atmospheric pressure. However, this solution requires separate production lines for producing the coated thin web material and to laminate it to the thicker web material, making also this process tedious, cumbersome and expensive.

[0009] There is therefore still a need for a more cost-efficient and speedy method and apparatus for providing a coating on a web material, such as a barrier coating on paper and / or paperboard, and in particular for relatively thick paperboard.

[0010] SUMMARY OF THE INVENTION

[0011] It is therefore an object of the present invention to at least partly alleviating the abovediscussed problems of the prior art and to address this need.

[0012] This object is obtained with an in-line web material processing apparatus for vacuum coating of the web material, wherein the web material is paper or paperboard, and a method for vacuum coating of such a web material, as defined in the appended claims.

[0013] According to a first aspect of the invention there is provided a method for vacuum coating of a web material of paper or paperboard comprising: receiving the web material through an inlet opening in an auxiliary vacuum chamber from ambient pressure; guiding the web material from the inlet opening to a transit opening through an inlet guide path; receiving the web material in a process vacuum chamber from said auxiliary vacuum chamber through said transit opening in said auxiliary vacuum chamber; coating the web material in the a process vacuum chamber; receiving the coated material in the auxiliary vacuum chamber through said transit opening; guiding the coated material from the transit opening to an outlet opening through an outlet guide path; outputting the coated material from the auxiliary vacuum chamber through said outlet opening; wherein the inlet guide path and the outlet guide path are separate from each other, wherein the inlet guide path and the outlet guide path over at least a part of their extensions are separated from each other by a separation distance of less than half a width of the web material.

[0014] According to another, corresponding, aspect of the invention there is provided an inline web material processing apparatus for producing a coated material, wherein the web material is paper or paperboard, the apparatus comprising: a process vacuum chamber comprising a vacuum coating unit for deposing a coating on the web material, and preferably an inorganic coating; and an auxiliary vacuum chamber comprising separate or combined inlet and outlet openings, at least the inlet opening forming a passage to ambient atmospheric pressure, and a transit opening, the transit opening forming a direct or indirect passageway between the auxiliary vacuum chamber and the process vacuum chamber; wherein an inlet guide path in the auxiliary chamber is arranged to guide a web material to be coated from the inlet opening to the transit opening and an outlet guide path in the auxiliary chamber is arranged to guide a coated web material from the transit opening to the outlet opening, and wherein the inlet guide path and the outlet guide path are separate from each other, wherein the inlet guide path and the outlet guide path over at least a part of their extensions are separated from each other by a separation distance of less than half a width of the web material.

[0015] The coating provided in the vacuum chamber may be referred to as vacuum coating or vacuum deposited coating. The vacuum deposition may be provided as physical vapor deposition, atomic layer deposition, chemical vapor deposition, and sputtering, or combinations thereof. Depending on the deposition method, different deposition sources may be used. The vacuum coatings or vacuum deposited coatings are very thin, and generally have a thickness of less than 500 nm.

[0016] The in-line web processing apparatus / method may comprise a single vacuum coating unit, but may alternatively comprise more than one vacuum coating units, such as two or three vacuum coating units. In case two or more vacuum coating units are provided, these may be arranged in one and the same process vacuum chamber, or, alternatively, be arranged in two or more separate process vacuum chambers.

[0017] The in-line web material processing machine / method provides a coating on a web material, such as paperboard, in a single, in-line process. The process may be performed with an endless web. Preferably, the machine / method operates in a roll-to-roll process, in which the web material to be processed is provided on a supply roll and the processed, coated web material is wound on rewind roll. However, the processed, coated web material may also, alternatively, be cut into sheets, in a roll-to-sheet process, or be taken care of in other ways. The processed, coated web material may also, additionally, or alternatively, continue into further in-line processes, such as in-line lamination, extrusion coating, and / or printing. Preferably, at least one of the supply roll and / or rewind roll, and most preferably both, are in atmospheric conditions or ambient conditions outside the vacuum deposition unit for performing any of the post converting or coating processes.

[0018] Due to the provision of the auxiliary vacuum chamber, the entire operation becomes faster, simpler and more cost-efficient. In the auxiliary vacuum chamber much of the moisture of the incoming web material will be evaporated, thereby drying the incoming web material and preparing it for the subsequent coating process. At the same time, some of the moisture evaporating from the incoming web material will moisture the coated web material, thereby improving the properties of the coated web material, which facilitates the further handling of the coated web material. The transfer of moisture from the incoming web material to the outgoing coated web material is particularly facilitated and made efficient by arrangement of the inlet guide path for the incoming web material and the outlet guide path for the outgoing coated web material to be at least partly parallel to each other. Hereby, several advantageous effects occur simultaneously. The incoming web material is dried and thereby better prepared for the subsequent coating process. The outgoing coated web material is moisturized and thereby also better prepared for subsequent handling and processing, e.g. by making it less fragile and less prone to be damaged during subsequent handling and processing. Further, a significant amount of moisture is hereby removed out from the auxiliary vacuum chamber together with the outgoing coated web material. This means that the amount of moisture which needs to be removed by the vacuum pumping is significantly reduced, thereby increasing the processing speed, lowering power consumption and also lowering the requirements on the vacuum pump. Overall, this makes the in-line web material processing apparatus faster and more cost-efficient.

[0019] This also enables arrangement of supply rolls of web material to be coated and rewinding rolls for taking up coated web material in atmospheric pressure, i.e. in ambient pressure outside the auxiliary vacuum chamber. This greatly facilitates the coating process, and makes it faster and more cost-effective. In an embodiment the in-line web material processing apparatus / method further comprises an unwinder reel holder for holding a supply roll of web material in ambient pressure outside said auxiliary vacuum chamber.

[0020] In a further embodiment, the in-line web material processing apparatus / method further comprises a rewinding reel holder for holding a rewinding reel for rewinding of the coated material in ambient pressure outside said auxiliary vacuum chamber.

[0021] An automatic reel change system may be provided, operable to change a supply roll on the unwinder reel holder and / or to change a rewinding reel on the rewinding roll holder.

[0022] The web material from a fresh supply role is preferably spliced to the web material of an old supply role, thereby allowing the process in the process vacuum chamber to continue without interruption.

[0023] Preferably, in the auxiliary vacuum chamber, the incoming, web material has a higher temperature, at least on a backside thereof, than at least a backside of the outgoing, coated web material. In an embodiment, the entire incoming, web material has a higher temperature than the outgoing, coated web material. However, if there is a temperature gradient in the material, it suffices that the temperature difference is present only at the sides facing each other, and preferably the backsides facing each other.

[0024] The temperature difference promotes the transfer of moisture from the incoming web material to the outgoing web material, since moisture evaporates more easily at a relatively higher temperature and is absorbed more efficiently at a relatively lower temperature.

[0025] The temperature difference may be obtained in various ways, such as heating the incoming web material before entry into the auxiliary vacuum chamber, such as when arranged at the supply roll or on its way from the supply roll to the auxiliary vacuum chamber. Heating of the web material may e.g. be effected by use of heated nip rolls. Such heated nip rolls may preferably be arranged outside the auxiliary vacuum chamber, but may additionally or alternatively be arranged inside the auxiliary vacuum chamber.

[0026] Additionally, or alternatively, the temperature difference may be obtained by cooling of the outgoing web material, after the vacuum coating, and preferably before entry into the auxiliary vacuum chamber, such as when in the process vacuum chamber, or on its way from the process vacuum chamber to the auxiliary vacuum chamber. Cooling of the web material may e.g. be effected by use of cooled nip rolls. Such cooled nip rolls may preferably be arranged outside the auxiliary vacuum chamber, but may additionally or alternatively be arranged inside the auxiliary vacuum chamber. The heated roll(s) provide a transfer of heat to the web material in contact with the roll(s). Similarly, cooled roll(s) provide a transfer of heat from the web material in contact with the roll(s) to the roll(s).

[0027] Additionally, or alternatively, transfer of moisture from the incoming web material to the outgoing web material may be made more efficient by electric field assistance. This can be effected by providing a difference in potential between the incoming and outgoing web materials, or between conducting elements arranged on the side of the outgoing and incoming web materials not facing each other.

[0028] In an embodiment, an electric potential difference is provided between a first conducting element arranged on a side of the web material in the inlet guide path being opposite to the web material of the outlet guide path and a second conducting element arranged on a side of the web material of the outlet guide path being opposite to the web material of the inlet guide path. The first and second conducting elements are preferably arranged close to the incoming and outgoing web material, respectively, and preferably in contact with the web material.

[0029] In such embodiments, one of the incoming and outgoing web materials may be grounded or negatively charged, whereas the other may be positively charged, or vice versa. Alternatively, conducting elements, e.g. in the form of metal plates, metal supports, metal conveyor, metal nips, metal rollers or the like can be arranged on the sides of the outgoing and incoming web materials opposite to each other. The conducting elements may be grounded, or have a potential opposite to the one of the other conducting element. Due to the potential difference, moisture will be more efficiently transferred. The applied potential may e.g. be in the range of 0.1-50 kV, such as in the range of 1-40 kV. The separation distance between the poles, be it between the web materials, between a web material and a separate conducting element or between two conducting elements, is preferably in the range of 1-50 cm, and preferably 5-30 cm.

[0030] The process generally becomes more efficient the longer the inline guide path and the outlet guide path runs in close vicinity of each other. In an embodiment, the inlet guide path and the outlet guide path are separated by a separation distance of less than half a width of the web material over at least 20% of their length extensions, and preferably over at least 50%, and most preferably over at least 70%. In embodiments, the inlet guide path and the outlet guide path may extend parallel to each other over essentially their whole length extensions, such as over at least 90%. Preferably, the inlet guide path and the outlet guide path are essentially parallel to each other, at least over part of their extensions, and preferably at least at parts separated by a separation distance of less than half a width of the web material.

[0031] The inlet and outlet guide paths may also have a curved or bent extension, allowing the guide paths to extend back and forth in a horizontal and / or vertical direction. Hereby, the length of the guide paths could be longer compared to the size of the vacuum chamber.

[0032] In an embodiment the inlet and outlet guide paths both have length extensions exceeding the longest of the length, width and height dimensions of the auxiliary vacuum chamber, and preferably by at least 50%, and more preferably by at least 75%, and more preferably by at least 100%.

[0033] To increase the length of the inlet and outlet guide paths, the auxiliary vacuum chamber may be provided with guide rolls allowing the guide paths to change directions inside the auxiliary vacuum chamber. In an embodiment, at least parts of the inlet and outlet guide paths may extend in a C- or U-shape in the auxiliary vacuum chamber.

[0034] The inlet guide path and the outlet guide path are preferably arranged relatively close to each other, at least at parts of their extensions. In an embodiment, the inlet guide path and the outlet guide path are separated from each other by a separation distance of less than 1 / 2 of the width of the web material, and preferably less than 1 / 4 of the width of the web material, and more preferably less than 1 / 10 of the width of the web material. The width of the web material can typically be in the range of 50-500 cm. A close arrangement of the inlet and outlet guide paths allows for a more efficient transfer of moisture from the incoming web material to be coated to the outgoing, coated web material.

[0035] The inlet guide path and the outlet guide path are preferably arranged so that noncoated backsides of the web material face each other. Hereby, the side to be coated of the incoming web material and the coated side of the outgoing, coated web material face away from each other, at least in the closely arranged parts of the inlet and outlet guide paths. This makes the transfer of moisture between the incoming web material to be coated and the outgoing, coated web material more efficient, e.g. by avoiding that the coating may have a negative impact on the uptake of moisture in the coated web material.

[0036] During production, a supply roll may be loaded onto a supply roll holder outside the auxiliary vacuum chamber, at atmospheric pressure. Web material from the supply roll is input into the auxiliary vacuum chamber through an inlet opening, and guided inside the auxiliary vacuum chamber through the inlet guide path to the transit opening of the auxiliary vacuum chamber. The web material is thereafter guided into the process vacuum chamber, possibly via one or more additional, intermediate vacuum chambers. After having been coated, the coated web material is guided back into the auxiliary vacuum chamber, again possibly via one or more additional, intermediate vacuum chambers, and guided via the outlet guide path to an outlet opening of the auxiliary vacuum chamber. Thereafter, the coated web material being discharged from the auxiliary vacuum chamber may be taken-up on rewind roll, or be guided to other processing stations.

[0037] The present invention also provides a more efficient process in terms of runnability and waste control, since shorter runs generally leads to more waste whereas longer runs reduces the amount of waste generated.

[0038] The inlet opening and outlet opening are preferably separate openings, and preferably arranged in the vicinity of each other. This allows for the inlet guide path and the outlet guide path to run closely, and preferably essentially in parallel, over a longer extension within the auxiliary vacuum chamber.

[0039] As already mentioned, the in-line web material processing apparatus / method may further comprise at least one intermediate vacuum chamber arranged between the auxiliary vacuum chamber and the process vacuum chamber. In an embodiment, one such intermediate vacuum chamber is provided. However, in other embodiments, two or more intermediate vacuum chambers may be provided.

[0040] Both the incoming web material to be coated and the outgoing, coated web material may be guided through one or more intermediate vacuum chamber(s). Alternatively, only the incoming web material or the outgoing, coated web material may be guided through one or more intermediate vacuum chamber(s).

[0041] In case both the incoming web material and the outgoing, coated web material are guided through an intermediate vacuum chamber, both the incoming web material and the outgoing, coated web material may be guided through the same, common intermediate vacuum chamber. In such embodiments, the guide paths in the intermediate vacuum chamber for the incoming, uncoated web material and the outgoing, coated web material be at least partly close to each other, to obtain a transfer of moisture, in the same or similar way as discussed in relation to the auxiliary vacuum chamber.

[0042] Alternatively, the incoming web material and the outgoing, coated web material may be guided through different intermediate vacuum chambers. In an embodiment, the incoming web material, i.e. the web material to be coated, is guided through at least one intermediate vacuum chamber.

[0043] The intermediate vacuum chamber(s) may provide further drying of the incoming web material and also provide a transition between different vacuum pressure levels, such as between a relatively higher vacuum pressure in the auxiliary vacuum chamber and a relatively lower vacuum pressure in the process vacuum chamber. The intermediate vacuum chamber(s) may also be used for one or more type of pre-treatment of the web material to be coated, and / or one or more type of post-treatment of the coated web material. The pre-treatment may e.g. be plasma treatment, corona treatment and / or flame treatment. Such pre-treatment can reduce the moisture content in the web material.

[0044] Thus, in an embodiment the in-line web material processing apparatus / method may further comprise a pre-treatment, such as a pre-treatment station, arranged in the auxiliary vacuum chamber and / or an intermediate vacuum chamber between the auxiliary vacuum chamber and the process vacuum chamber for pretreatment of the web material prior to coating, the pre-treatment preferably being at least one of flame treatment, corona treatment and plasma treatment.

[0045] The vacuum coating unit, also referrable to as vacuum coater, may be of a type as is per se previously known. The vacuum coating unit may e.g. be realized as disclosed in US 2020 / 0165721 and / or WO 2022 / 090337, both said documents hereby being incorporated in their entirety by reference.

[0046] Preferably, the vacuum coating unit is a vapor deposition unit. The vapor deposition unit may be a physical vapor deposition unit using a coating material in a liquid or solid state or a chemical vapor deposition unit using a chemical vapor. Sometimes such vapor deposition units are called metallizers even if the coating material is not necessarily a metal in the strict sense but could also be a partially oxidized metal, such as A1OXor AI2O3, or other vapor deposited inorganic materials, such as SiOxor SiCh. Such vapor deposition units are suitable for providing films or layers of coating material in a precise and efficient manner.

[0047] The coating provided by the vacuum coating unit can e.g. be a metallization, an organic coating and / or a ceramic coating. Hybrid or mixtures of the above-discussed materials may also be used, such as an Si doped Al layer. The vacuum coating unit may be arranged to deposit a coating on the web material of a vapor deposited inorganic material, such as metal or metal oxide, and preferably aluminum or aluminum oxide. However, alternatively the vacuum coating unit may be a physical vapor deposition unit, e.g. arranged to provide EB-PVD. The vacuum coating unit may also be arranged to provide the coating by sputtering, such as magnetron sputtering.

[0048] In a preferred embodiment, the coating comprises, or is entirely made of, aluminum or aluminum oxide. However, other inorganic coating materials may also be used, such as silicon oxide. Organic coating materials may also be used, comprising carbon, e.g. in the form of Diamond Like Carbon, DLC, and the like.

[0049] The coating preferably forms a barrier against liquids, such as water, and / or gases, such as vapor or oxygen. The coating preferably forms a gas impermeable barrier layer.

[0050] The coating is preferably relatively thin, such as in the range from 10 nanometers to 500 nanometers. Such thin coatings may not provide barrier against liquid but is mostly used to provide barrier against water vapor, or gases, such as oxygen or CO2, aroma, and / or radiation, such as light or UV light. Possibly, it could also provide a barrier against greases and oils or aromatics. In order to provide a good barrier, the vacuum coated layers are preferably arranged on relatively smooth and dense surfaces in order to provide a pinhole free surface.

[0051] However, thicker coatings may also provide impermeability to liquids etc. Further, additional plastic or polymer layer(s) may be added, preferably on top of the coating, to provide scratch resistance or durability to the vacuum coated layer, but may additionally or alternatively be used to form a liquid barrier and heat sealability.

[0052] The vapor coating unit may comprise a chamber in which a wire of coating material, e.g. aluminum, is fed onto individual, resistance-heated inter-metallic evaporators such that the wire becomes molten and evaporates.

[0053] The coating preferably has a much lower thickness than the thickness of the web material. The coating may e.g. have a thickness of less than 1% of the thickness of the web material. The coating may e.g. have a thickness in the range of 10-500 nm, and preferably 20- 300 nm.

[0054] According to an embodiment the vacuum coating unit comprises an area for guiding the web material. This could be for example a processing drum for supporting the web material to be processed. Another possibility could be for example to guide the web in a free span manner without the use of a processing drum. In the free span arrangement the web material to be vacuum coated is held in an unsupported / free span arrangement between supporting rollers with the evaporation source and evaporant material applied via evaporation and condensing the evaporant on the web material in an unsupported and uncooled manner. An advantage with the drum embodiment is e.g. the cooling effect provided by the drum. An advantage of the free span arrangement is e.g. the reduced risk of deformation of the web material and the coating.

[0055] The process vacuum chamber may comprise a single vacuum zone, accommodating the vacuum coating unit. However, the process vacuum chamber may alternatively comprise two or more separated vacuum zones, which may have different vacuum pressures, as is per se known in the art. For example, a vacuum zone having lower pressure may be arranged at the vacuum coating unit, where the coating takes place, whereas a slightly higher pressure may be provided before and / or after the vacuum coating unit, thereby forming an intermediate vacuum chamber, as discussed in the foregoing.

[0056] For example, the vacuum pressure in the part of the process vacuum chamber where the coating takes place may be a low vacuum pressure of 1 x 10'5bar or less, and preferably 1 x 10'6bar or less, and preferably 1 x 10'7bar or less. Such a low vacuum pressure is beneficial for the coating process since it makes the coating material easier to evaporate and making it possible to evaporate the coating material at a lower temperature. In addition, the low vacuum pressure lowers the risk of the evaporated atoms to be scattered by residual gas molecules, and to possibly react with such residual gas molecules.

[0057] The vacuum of the auxiliary vacuum chamber, and the possible one or more intermediate vacuum chambers, may have the same low vacuum pressure. However, preferably the vacuum pressure in the process vacuum chamber is lower than the vacuum pressure in the auxiliary vacuum chamber. The vacuum pressure in any intermediate vacuum chamber(s) is preferably somewhere between the vacuum pressure of the auxiliary vacuum chamber and the process vacuum chamber, thereby forming a smooth transition in pressure levels.

[0058] The vacuum pressure in the auxiliary vacuum chamber may be somewhat higher than the vacuum pressure in the process vacuum chamber, such as 1 x 10'5bar or more, and preferably 1 x 10'4bar or more, such as about 1 x 10'3bar or more.

[0059] The vacuum zones of the auxiliary vacuum chamber, the process vacuum chamber and the possible one or more intermediate vacuum chamber(s) are preferably not provided with totally air tight separation, and a small gap may exist between the zones, e.g. large enough for the incoming and outgoing web material to be moved between the chambers. The separation may e.g. be provided in the form of narrow slit openings, a gap sluice, or the like, as is per se known in the art. However, other arrangements to provide more efficient sealing between the chambers may be used. Such openings may e.g. be realized by nip rollers and the like.

[0060] In an embodiment, at least one, and preferably all, of the inlet, outlet and a transit openings are provided with one or more nip roller, and preferably a pair of closely arranged nip rollers.

[0061] Further measures may be taken to reduce the amount of air leaking in, especially through the inlet opening of the auxiliary vacuum chamber.

[0062] In an embodiment, a pair of air leading foils may be arranged in the vicinity of the inlet opening and external of the auxiliary vacuum chamber. The air leading foils may be arranged essentially to contact the web material entering through the inlet opening, in a duckbill arrangement. Hereby, due to the venturi effect, the pressure in the vicinity of the inlet opening will be reduced, thereby further limiting the amount of air leaking into the auxiliary vacuum chamber.

[0063] The optional automatic reel change system may be of any type per se known in the art, and used for example for reel changes in printing presses. Such automatic reel change systems are e.g. known from US 3907235, US 4111741, US 4077580, US 4278213, US 4233104, US 4875633, etc, all of said documents hereby being incorporated in their entirety by reference.

[0064] Due to the automatic reel change system, a so-called flying roll change can be performed, to that upon depletion of a roll of material, the coating process need not be stopped. In this process, the old, depleted or almost depleted supply roll is exchanged to a new supply roll. The new web material, of the new supply roll, is preferably spliced or in other ways connected to the old web material, of the old supply roll. Hereby, a continuous, endless web material is formed. The splicing may e.g. be obtained by adhesive tapes, by adhesive, or the like. For this purpose, the new supply roll may be provided with an adhesive tape, gluing spots or the like, on an outer layer, for use in accomplishing a connection with the web material of the roll of material which is running out.

[0065] During on-the-fly roll change, the fresh web material is then accelerated to a circumferential speed corresponding to the web speed of the established roll of material. In the course of the actual web change, the start of the web of the fresh roll of material is connected with the web of material on the roll of material which is running out, and the web of material on the roll of material which is running out is cut at substantially the same time. In this way, the start of the web of the fresh web of material is drawn into the coating process by the old web of material and a stoppage of the process is avoided. The web material to be processed is a paper or paperboard material, i.e. a fiber-based material, and more precisely a cellulose-based material. The web material may be at least one of a paperboard material, a thick paper and a low density, bulky paper, and preferably a paperboard material. The machine and method of the present invention is particularly useful for such materials having a relatively great thickness and / or a relatively great grammage.

[0066] In an embodiment, the web material to be processed is at least one of paperboard material, thick paper, low density, bulky paper and cellulose based substrate.

[0067] The web material to be processed preferably has a grammage of at least 30 g / m2, and preferably much higher, such as at least 150 g / m2, and more preferably at least 200 g / m2, and even more preferably of at least 250 g / m2. The grammage is preferably not more than 650 g / m2. In an embodiment, the web material to be processed may have a grammage in the range of 200-650 g / m2. Grammage may be determined in accordance with the standard ISO 536.

[0068] The density of the web material to be processed in at least one layer is preferably less than 950 kg / m3, and preferably less than 700 kg / m3, and more preferably less than 600 kg / m3, and most preferably less than 550 kg / m3, as determined in accordance with ISO 534. The material may be a single layer material, having the same, uniform, density in all layers. However, the material may also be a multi-layer material, a multiply. In such embodiments, the density may be different in different layers. The low density as discussed above may in such embodiments be provided in at least one of the layers.

[0069] In an embodiment, the web material to be processed has a grammage of 60 g / m2or more and a density of less than 700 kg / m3, and preferably less than 650 kg / m3, and more preferably less than 600 kg / m3, and most preferably less than 550 kg / m3.

[0070] However, in other embodiments, the web material may have a higher density. For example, the web material may be mineral coated or HD paper, for which the density may be significantly higher, such as above 1000 kg / m3, such as in the range of 1000-1400 kg / m3.

[0071] The web material to be processed preferably has a thickness of at least 300 microns, and preferably of at least 350 microns, and more preferably of at least 500 microns. The thickness is preferably not more than 1500 microns. In an embodiment the thickness is in the range of 350-1000 microns. The thickness may be determined in accordance with the standard ISO 534. However, in other embodiments, thinner web materials may be used, e.g. having a thickness of 25-300 microns. Materials, and in particular paperboard or thick paper, having such a thickness and / or grammage is generally difficult to handle in an effective way in currently available coating solutions, but can easily be handled by the apparatus and method of the present invention.

[0072] The web material preferably has a relatively smooth surface, at least on the side to be coated. The smoothness may e.g. be expressed in terms of Parker Print Surf (PPS) roughness. The surface roughness in pm of the surface may be determined by a Parker Print Surf (PPS) device operated at a clamping pressure of 1.0 MPa, such as devices available from Testing Machines Inc., New York, USA. The web material preferably has a PPS 1.0 Smoothness of less than 3.0 microns. The Parker Print Surf (PPS) roughness may be determined in accordance with the standard ISO 8791-4.

[0073] Another characteristic of the web material that may be used is the bulk value. Bulk is used to measure the ratio of paper thickness to its weight in cubic centimeters per gram. Density is the basis weight, grammage, divided by the caliper, i.e. the thickness. Bulk is the inverse of the density, i.e. caliper divided by grammage. Here, the web material preferably has a bulk of more than 1.20, and more preferably more than 1.4. The bulk value may be determined in accordance with the standard ISO 534.

[0074] The coated material leaving the processing apparatus according to the invention may be provided with excellent structural and barrier properties and is very useful for packaging goods, e.g. food, liquids and pharmaceuticals. The invention enables facilitated processing, use of less and less costly materials, and / or improved performance. For example, the invention enables use of a reduced amount of plastic coating, reduced need for additional high barrier structures, and / or a performance not easily achievable with single polymer layers.

[0075] The in-line web material processing machine may further comprise a rewinder reel holder for holding a rewinding reel for rewinding of the coated material. Hereby, the processed, coated material may be assembled on a second roll. In this case, the process may be a roll-to-roll process. Such a process is generally the most efficient. However, alternatively the coated material may also be cut into sheets in a roll-to-sheet process.

[0076] In a roll-to-roll process, the rewinding reel holder is preferably arranged outside the auxiliary vacuum chamber, in atmospheric pressure.

[0077] The in-line web material processing apparatus may further comprise an extrusion or lamination unit for forming a film on the coating of the web material to be processed. Thus, in addition to the coating, preferably forming the barrier layer on the web material, an additional layer may be added. This additional layer is preferably arranged on-top of the vacuum deposited coating, the coating e.g. a barrier layer. This additional layer may e.g. be a polymeric layer, forming a protective layer over the barrier layer. Additionally, or alternatively, the coating and the film of the second coating material may both act as barriers blocking moisture and / or gases from passing through the coated material. Also, or additionally, the film provides a protective layer, alleviating the risk of contamination and / or mechanical damage.

[0078] The extrusion or lamination unit is optionally arranged inside one of the vacuum chambers, and positioned after the vacuum coating unit with respect to a processing direction. However, alternatively, the extrusion or lamination unit may be arranged outside the processing auxiliary vacuum chamber. The extrusion or lamination unit may in such an embodiment be arranged in an in-line arrangement, but may alternatively be a separate, offline unit, such as an off-line extrusion coater, for coating of at least one side of the web material. The coating or laminated layer may e.g. comprise polyolefin.

[0079] In an embodiment, a polyolefin layer / coating may be arranged on both sides of the web material, e.g. forming a layered structure comprising the layers: polyolefin; paperboard; metallized layer; and polyolefin. In another embodiment, a primer or barrier coating may be arranged on the paperboard prior to the arrangement of the metallized layer. Such an embodiment may comprise the layers: polyolefin; paperboard; primer or barrier coating; metallized layer; and polyolefin. In yet another embodiment, a polyolefin layer is arranged only on one side of the paperboard. Further, an additional barrier layer may be arranged between the paperboard and the metallized layer. Such an embodiment may comprise the layers: paperboard; barrier layer; metallized layer; and extrusion coated layer(s).

[0080] The in-line web material processing machine may additionally, or alternatively, comprise a printing unit to provide a print on a coated or non-coated side of the web material.

[0081] The vacuum in the processing vacuum chamber, the loading vacuum chamber and / or the output vacuum chamber may be provided by independently operable vacuum systems. If totally separated systems are used, each system uses its own equipment, such as vacuum pumps, and is independently controllable. However, it is also feasible to use one or more common vacuum pumps. In such an embodiment, the pump(s) may be used intermittently to evacuate pressure from the chambers in turns.

[0082] The vacuum pressure in the process vacuum chamber, and preferably also in the other vacuum chambers, is preferably below 1 x 10'1Torr (1.3 x 10'5Mpa) and more preferably below 1 x 10'2Torr (1.3 x 10'6Mpa). The web material may have a width in the range of 0.5-4 m, and preferably in the range of 1-3 m, and more preferably in the range of 1.5-2.5 m, such as about 2 m.

[0083] In an automated process, involving the roll / reel changes at the input side, and optionally at the output side, the web material speed through the coating apparatus / method is preferably over 100 m / min, and preferably over 200 m / min, and most preferably 300 m / min or more. In addition, the web material speed through the coating apparatus / method is preferably less than 1500 m / min.

[0084] The coating may be arranged on one side of the web material, or on two sides. The coating may further be provided as a single coating or as a double coating. If more than one coating layers are to be provided, more than one vacuum coating units may also be used.

[0085] Similar additional features and details as disclosed in relation to the first discussed aspect of the invention are possible also in respect of the second aspect, and vice versa, and the same or similar advantages and benefits are obtained.

[0086] BRIEF DESCRIPTION OF THE DRAWINGS

[0087] The present invention will be described in more detail with reference to the appended drawings, showing currently preferred embodiments of the invention.

[0088] Fig. la is a schematic illustration of an in-line web material processing apparatus for producing a coated material, in accordance with an embodiment.

[0089] Fig. lb is a schematic illustration of an arrangement for providing an electric field in the auxiliary vacuum chamber of Fig. la, in accordance with an embodiment.

[0090] Fig.2 is a schematic illustration of an alternative vapor coating unit useable in embodiments of the in-line web material processing apparatus.

[0091] Figs. 3, 4a-c, 5 and 6 are schematic illustrations of various vacuum chamber configurations useable in combination with the embodiments of Figs. 1 and 2.

[0092] Figs. 7a-c are illustrations of an automatic reel changer system in accordance with an embodiment and illustrating different steps during a reel change.

[0093] Figs. 8a-c are illustrations of an automatic reel changer system in accordance with another embodiment and illustrating different steps during a reel change.

[0094] Fig. 9 is a schematic illustration of coating processes according to various possible embodiments. DETAILED DESCRIPTION OF CURRENTLY PREFERRED EMBODIMENTS

[0095] In the following detailed description, preferred embodiments of the present invention will be described. However, it is to be understood that features of the different embodiments are exchangeable between the embodiments and may be combined in different ways, unless anything else is specifically indicated. Even though in the following description, numerous specific details are set forth to provide a more thorough understanding of the present invention, it will be apparent to one skilled in the art that the present invention may be practiced without these specific details. In other instances, well known constructions or functions are not described in detail, so as not to obscure the present invention.

[0096] With reference to Fig. la, an in-line web material processing apparatus 1 for producing a coated material 2 comprises two or more vacuum chambers 3, including a process vacuum chamber 31, an auxiliary vacuum chamber 32 and, optionally, one or more intermediate vacuum chamber(s) 33. The vacuum chambers may be operated independently of each other. In an embodiment, the vacuum chambers may be operated by independent vacuum systems, each having separate vacuum pumps. However, the same pump may also be used for two or more of the vacuum chambers, and may e.g. be arranged to operate intermittently and in sequence on the different vacuum chambers.

[0097] The two or more vacuum chambers are preferably arranged adjacent each other, and are in communication with each other through one or more openings. An opening may be formed in a common wall separating two of the chambers, or through a tubular element connecting two of the chambers.

[0098] For example, the auxiliary vacuum chamber 32 and the process vacuum chamber 31 may be separated by a common wall 311. Additionally, or alternatively, the auxiliary vacuum chamber 32 and an intermediate vacuum chamber 33 may be separated by the common wall.

[0099] The opening(s) into, out from, and between the chambers can be provided in the form of narrow slit openings, a gap sluice, or the like, as is per se known in the art. However, in the illustrative example, the openings are realized by nip rollers, and preferably a pair of closely arranged nip rollers.

[0100] In the illustrative example, the auxiliary vacuum chamber 32 comprises an inlet opening 321, formed by a pair of nip rollers 322, an outlet opening 323, formed by a pair of nip rollers 324, an ingoing transit opening 325, formed by a pair of nip rollers 326, and an outgoing transit opening 327, formed by a pair of nip rollers 328. Even though separate transit openings are preferred for the ingoing and outgoing web material, a single transit opening may also be used.

[0101] The chamber forming the process chamber 31 may be used solely as a process chamber. However, the chamber may optionally also be divided by separation walls 312 to form a first part, forming an intermediate vacuum chamber 33 and the process vacuum chamber 31. In the illustrative example, the separation walls 312 extend towards a process drum used for the vapor coating, to be discussed in more detail in the following. However, alternatively, the intermediate vacuum chamber may be arranged entirely separated from the process vacuum chamber, and in such embodiments the opening(s) between the intermediate vacuum chamber and the process chamber may also be realized e.g. with nip rollers.

[0102] To further reduce the amount of air leaking in through the inlet opening 321 of the auxiliary vacuum chamber a pair of air leading foils 322’ may be arranged in the vicinity of the inlet opening and external of the auxiliary vacuum chamber. The air leading foils 322’ may be arranged essentially to contact the web material entering through the inlet opening, in a duckbill arrangement. Hereby, due to the venturi effect, the pressure in the vicinity of the inlet opening will be reduced, thereby further limiting the amount of air leaking into the auxiliary vacuum chamber.

[0103] A vacuum coating unit 5 is provided in the process vacuum chamber for deposing a coating on the web material 2.

[0104] Arranged externally from the vacuum chambers are processing equipment for handling the web material before and after the coating process. In the illustrative example, an unwinder reel holder 41 is arranged for holding a first supply roll 61 of web material 2 to be processed.

[0105] The in-line web material processing apparatus may further comprise a rewinder reel holder 41 for holding a rewinding reel for rewinding of the coated web material. Hereby, the processed, coated material may be assembled on a rewinding roll 62. In this case, the process may be a roll-to-roll process. Such a process is generally the most efficient. However, alternatively the coated material may also be cut into sheets, e.g. already in the processing vacuum chamber, or outside this chamber, in a roll-to-sheet process. The process may also comprise edge trimming of the processed web material.

[0106] During production, a supply roll may be loaded onto the supply roll holder 41 outside the auxiliary vacuum chamber 32, at atmospheric pressure. Web material 2 from the supply roll is input into the auxiliary vacuum chamber 32 through the inlet opening 321, and guided inside the auxiliary vacuum chamber through an inlet guide path to the transit opening 325 of the auxiliary vacuum chamber. The web material is thereafter guided into the process vacuum chamber 31, possibly via one or more additional, intermediate vacuum chambers 33. After having been coated, the coated web material is guided back into the auxiliary vacuum chamber 32, again possibly via one or more additional, intermediate vacuum chambers 33, and guided via an outlet guide path to the outlet opening 323 of the auxiliary vacuum chamber 32. Thereafter, the coated web material being discharged from the auxiliary vacuum chamber may be taken-up on the rewind roll 62, or be guided to other processing stations.

[0107] The inlet guide path in the auxiliary chamber is arranged to guide a web material to be coated from the inlet opening 321 to the transit opening 325 and an outlet guide path in the auxiliary chamber is arranged to guide a coated web material from the transit opening 327 to the outlet opening 323. The inlet guide path and the outlet guide path are separate from each other and at least partly closely arranged to each other. Preferably, the inlet guide path and the outlet guide path are close to each other, i.e. having a separation distance of less than 1 / 2 the width of the web material, over at least 20% of their length extensions, and preferably over at least 50%, and most preferably over at least 70%. In embodiments, the inlet guide path and the outlet guide path may extend parallel to each other over essentially their whole length extensions, such as over at least 90%.

[0108] The inlet and outlet guide paths may also have a curved or bent extension, allowing the guide paths to extend back and forth in a horizontal and / or vertical direction. Hereby, the length of the guide paths could be longer compared to the size of the vacuum chamber. To increase the length of the inlet and outlet guide paths, the auxiliary vacuum chamber may be provided with guide rolls 329 allowing the guide paths to change directions inside the auxiliary vacuum chamber. In the illustrative example, at least parts of the inlet and outlet guide paths extend in two differently directed C- or U-shapes in the auxiliary vacuum chamber.

[0109] The inlet guide path and the outlet guide path are arranged relatively close to each other, at least at parts of their extensions, and preferably the paths are essentially parallel to each other at these parts. In an embodiment, the inlet guide path and the outlet guide path, at least at said parts, are preferably separated from each other by a separation distance of less than a 1 / 2 a width of the web material, and preferably less than 1 / 4 of the width of the web material, and more preferably less than 1 / 10 of the width of the web material.

[0110] In the illustrative example, the inlet guide path and the outlet guide path are arranged so that non-coated backsides of the web material face each other. Hereby, the side to be coated of the incoming web material and the coated side of the outgoing, coated web material face away from each other, at least in the closely arranged parts of the inlet and outlet guide paths.

[0111] The in-line web material processing apparatus may further comprise a pre-treatment station 7 arranged in the auxiliary vacuum chamber and / or an intermediate vacuum chamber between the auxiliary vacuum chamber and the process vacuum chamber for pretreatment of the web material prior to coating. The pre-treatment is preferably at least one of flame treatment and plasma treatment.

[0112] The in-line web material processing apparatus may further comprise a post-treatment station 8, such as an extrusion or lamination unit for forming a film on the coating of the web material to be processed and / or a printing unit to provide a print on a coated or non-coated side of the web material.

[0113] The in-line web material processing apparatus may also include a post-treatment station 8’ arranged to provide additional moisture to the coated web material. Such a remoisturizing unit 8’ may e.g. be arranged close to the outlet 323, and may e.g. be arranged to expose the web material to steam. The remoisturizing unit 8’ is preferably arranged on the non-coated side, i.e. the backside, of the coated web material.

[0114] One or more pre-treatment stations or units 9 may also be arranged outside the auxiliary vacuum chamber 32. Such stations / units may e.g. be used to apply a precoat onto the web-material to be coated, for drying of the web material, etc.

[0115] The web material to be processed, and supplied on the supply rolls, is preferably a fiber-based material, and preferably a paperboard material. The web material is preferably relatively thick, with a grammage of at least 150 g / m2, and a thickness of at least 300 microns. However, materials with lower grammage, such as of 60 g / m2or more, may also be used, in particular for materials having one or more layers of low density, such as less than 600 kg / m3.

[0116] The supply roll may e.g. have a width in the range of 0.5-4 m, and in particular 1.5-3 m, such as 2 m, and may have a diameter in the range of 1-3 m, such as 1.5 or 2 m. A supply roll of relatively thick paperboard may e.g. contain a length of web material of 5-25 km, such as 10 km.

[0117] The vacuum coating unit, also referrable to as vacuum coater, may be of a type as is per se previously known. The vacuum coating unit may e.g. be realized as disclosed in US 2020 / 0165721 and / or WO 2022 / 090337, both said documents hereby being incorporated in their entirety by reference. Preferably, the vacuum coating unit is a vapor deposition unit. The vapor deposition unit may be a physical vapor deposition unit using a coating material in a liquid or solid state, an atomic layer deposition unit, or a chemical vapor deposition unit using a chemical vapor. This may also be referred to as metallization. The coating may e.g. comprise or consist of aluminum or aluminum oxide. The coating preferably forms a barrier against liquids, such as water, and / or gases, such as vapor or oxygen. The coating preferably forms a gas and / or liquid impermeable barrier layer.

[0118] To promote transfer of moisture from the incoming web material to the outgoing web material, a temperature difference may be provided between the incoming and outgoing web material. This may e.g. be realized by heating and / or cooling of one or more of the rollers 329.

[0119] Additionally, or alternatively, transfer of moisture from the incoming web material to the outgoing web material may be made more efficient by electric field assistance. This can be effected by providing a difference in potential between the incoming and outgoing web materials, or between conducting elements arranged on the side of the outgoing and incoming web materials not facing each other.

[0120] In the exemplary embodiment illustrated in Fig. lb, incoming web material from supply roll 61 when guided along the inlet guide path in the auxiliary vacuum chamber is guided past a first conducting element, here in the form of a conducting roll 329a, and the outgoing web material, to be forwarded to the rewind roll 62, when guided along the outlet guide path in the auxiliary vacuum chamber is guided past a second conducting element, here in the form of a conducting roll 329b. The rolls 329a, 329b, are arranged on the sides of the incoming and outgoing web materials facing away from each other, and are in contact with the web material. A potential difference is provided between the first and second conducting element. In the illustrative example the roll 329a is connected to an electric potential V, whereas the other roll 329b is connected to the ground.

[0121] According to an embodiment the vacuum coating unit 5 comprises an area for guiding the web material. This could be for example a processing drum 51 for supporting the web material to be processed.

[0122] Another possibility for coating the web material, and as shown in Fig. 2, is to guide the web material in a free span manner without the use of a processing drum. In the free span arrangement the web material to be vacuum coated is held in an unsupported / free span arrangement between supporting rollers 52 with the evaporation source and evaporant material applied via evaporation and condensing the evaporant on the web material in an unsupported and uncooled manner. In such an embodiment, a back support 53 may be provided for aiding in e.g. cooling of the coating and / or stabilization of the web. The back support may provide a fixed surface, and may e.g. be arranged as a plate of metal or the like. Alternatively, the back support may be moveable, and preferably moveable in conjunction with the web material. The back support may in such embodiments be realized as a conveyor, and preferably with a metal conveyor belt.

[0123] Moreover, one or more additional rollers or drums may be provided to facilitate the flow of the web material 2 through the vacuum chambers, from the unwinding position and the supply roll, and the rewinding position, and an optional rewinding roll.

[0124] As already mentioned, the in-line web material processing apparatus may comprise only the auxiliary vacuum chamber 32 and the process vacuum chamber, as illustrated schematically in Fig. 3.

[0125] Alternatively, a common intermediate vacuum chamber 33 may be provided, as illustrated schematically in Fig. 4a. More than one intermediate vacuum chamber may also be provided, such as schematically illustrated in Figs. 4b and 4c. In the embodiment of Fig. 4b, a second intermediate vacuum chamber 33’ is provided in addition to the first intermediate vacuum chamber 33. In the embodiment of Fig. 4c, a third intermediate vacuum chamber 33” is provided, in addition to the first and second intermediate vacuum chambers.

[0126] In other alternative embodiments, separate intermediate vacuum chambers 33 may be provided for the incoming and outgoing web material 2, as illustrated schematically in Fig. 5, or an intermediate vacuum chamber may be provided only for the ingoing web material, as illustrated schematically in Fig. 6.

[0127] Further alternatives are also feasible, such as use of more than one intermediate vacuum chamber instead of any of the intermediate vacuum chambers discussed in relation to the embodiments discussed in the foregoing.

[0128] The vacuum of the auxiliary vacuum chamber, and the possible one or more intermediate vacuum chambers, may have the same low vacuum pressure. However, preferably the vacuum pressure in the process vacuum chamber is lower than the vacuum pressure in the auxiliary vacuum chamber. The vacuum pressure in any intermediate vacuum chamber(s) is preferably somewhere between the vacuum pressure of the auxiliary vacuum chamber and the process vacuum chamber, thereby forming a smooth transition in pressure levels. Preferably, the apparatus operates in a roll-to-roll process, in which the web material to be processed is provided on a supply roll and the processed, coated web material is wound on rewind roll. However, the processed, coated web material may also be cut into sheets, in a roll-to-sheet process, or be taken care of in other ways.

[0129] An automatic reel change system may be used for either or both of the unwinding side and the rewinding side. The automatic reel change system may be of any type per se known in the art, and used for example for reel changes in printing presses. Such automatic reel change systems are e.g. known from US 3907235, US 4111741, US 4077580, US 4278213, US 4233104, US 4875633, etc, all of said documents hereby being incorporated in their entirety by reference.

[0130] Due to the automatic reel change system, a so-called flying roll change can be performed, so that upon depletion of a roll of material, the coating process need not be stopped. In this process, the old, depleted or almost depleted supply roll is exchanged to a new supply roll. The new web material, of the new supply roll, is preferably spliced or in other ways connected to the old web material, of the old supply roll. Hereby, a continuous, endless web material is formed. The splicing may e.g. be obtained by adhesive tapes, by adhesive, or the like. For this purpose, the new supply roll may be provided with an adhesive tape, gluing spots or the like, on an outer layer, for use in accomplishing a connection with the web material of the roll of material which is running out.

[0131] During on-the-fly roll change, the fresh web material is then accelerated to a circumferential speed corresponding to the web speed of the established roll of material. In the course of the actual web change, the start of the web of the fresh roll of material is connected with the web of material on the roll of material which is running out, and the web of material on the roll of material which is running out is cut at substantially the same time. In this way, the start of the web of the fresh web of material is drawn into the coating process by the old web of material and a stoppage of the process is avoided.

[0132] Two embodiments of automatic reel change systems are shown in Figs. 7a-c and Figs. 8a-c.

[0133] In the embodiment of Figs. 7a-c, the automatic reel change system 4 comprises a reel holder 41 in the form of a rotatable reel arm, having two separate reel holding positions arranged at the opposed ends. A drive belt 42 is arranged to rotate the supply roll 51. Fig. 7a shows a state in which a relatively full supply roll 61 is provided in the reel holder 41 and unwinding of the reel is made continuously. The rotatable reel arm can be rotated while the roll is unwound. In Fig. 7b, the supply roll is almost empty, and need to be changed. A new supply roll 61 is then moved towards the reel holder 41, e.g. by pivotable arms 43. In the state illustrated in Fig. 7c, the new supply roll 61 is accelerated up to production speed, and a splicer 44 splices the new web to the old web at operational speed. The used reel 61 ’ is at the same time cut off and removed from the reel holder 41.

[0134] In the embodiment of Figs. 8a-c, the automatic reel change system 4 comprises a reel holder 41’ in the form of a rotatable reel star with three arms, having three separate reel holding positions arranged at the ends of the arms. A drive belt 42 is arranged to rotate the supply roll 61. Fig. 8a shows a state in which a supply roll 61 is being unwound and held in the upwardly directed reel holding arm. In Fig. 8b, the supply roll is almost empty, and need to be changed. A new supply roll 61 is then moved towards the uppermost position, by rotation of the reel holder 41’. In the state illustrated in Fig. 8c, the new supply roll 61 is accelerated up to production speed, and a splicer 44 splices the new web to the old web at operational speed. The used reel 61’ is at the same time cut off from the reel holder 41’.

[0135] In the so far discussed embodiments, the processing involves only a single vacuum coating step, performed by the vacuum coating unit. However, additional process steps could also be used, such as one or more additional coating steps, performed by one or more additional vacuum coating units. Provision of a film layer over the coating, such as by an extrusion or lamination unit, could also be contemplated. Additionally, or alternatively, a printing unit may be provided to print text or pictures on the web material.

[0136] Such embodiments, which may be used in combination with any of the abovediscussed embodiments, are schematically illustrated in Fig. 9. In this embodiment, a number of processing units are illustrated, as dashed boxes, in addition to the vacuum coating unit. In embodiments, all of these additional processing units 54a-c may be used, or alternatively only one or two of them, in any combination.

[0137] In an embodiment, the in-line web material processing machine may further comprise a second coating unit 54a. The second coating unit may be of the same type as the vacuum coating unit discussed in the foregoing, but may also be of a different type.

[0138] Additionally, or alternatively, the in-line web material processing machine may further comprise an extrusion or lamination unit 54b, for forming a film on the coating of the web material to be processed. Thus, in addition to the coating, preferably forming the barrier layer on the web material, an additional layer may be added. This additional layer is preferably arranged on-top of the barrier layer. This additional layer may e.g. be a polymeric layer, forming a protective layer over the barrier layer. Additionally, or alternatively, the coating and the film of the second coating material may both act as barriers blocking moisture and / or gases from passing through the coated material. Alternatively, or additionally, the film may provide a protective layer, alleviating the risk of contamination and / or mechanical damage.

[0139] The optional additional coating unit, and optional extrusion or lamination unit, may be arranged inside the process vacuum chamber 31, and preferably positioned after the vacuum coating unit 5 with respect to a processing direction. However, alternatively, optional additional coating unit and extrusion or lamination unit may be arranged outside the processing vacuum chamber 31.

[0140] A printing unit 54c may also be used, to print text or other forms of visual information on the coated web material. The printing unit may also be arranged inside the processing vacuum chamber 31, or alternatively outside this chamber.

[0141] The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. For example, more than two vacuum chambers may be used, such as three or four. Further, different types of vacuum coating units and automatic reel change systems may be employed. Further, even though a preferred application is coating of paperboard, other web materials may also be used, such as thinner paper. Other types of coatings may also be used, such as ceramic coatings, carbon containing coatings, etc.

Claims

CLAIMS1. A method for vacuum coating of a web material (2) of paper or paperboard comprising: receiving the web material through an inlet opening (321) in an auxiliary vacuum chamber (32) from ambient pressure; guiding the web material from the inlet opening (321) to a transit opening (325, 327) through an inlet guide path; receiving the web material in a process vacuum chamber (31) from said auxiliary vacuum chamber (32) through said transit opening (325, 327) in said auxiliary vacuum chamber; coating the web material in the process vacuum chamber (31); receiving the coated material in the auxiliary vacuum chamber (32) through said transit opening (325, 327); guiding the coated material from the transit opening (325, 327) to an outlet opening (323) through an outlet guide path; outputting the coated material from the auxiliary vacuum chamber (32) through said outlet opening (323); wherein the inlet guide path and the outlet guide path are separate from each other, wherein the inlet guide path and the outlet guide path over at least a part of their extensions are separated from each other by a separation distance of less than half a width of the web material.

2. The method of claim 1, wherein the inlet opening (321) and outlet opening (323) are separate openings, and preferably arranged in the vicinity of each other.

3. The method of any one of the preceding claims, further comprising guiding the web material trough at least one intermediate vacuum chamber (33) arranged between the auxiliary vacuum chamber (32) and the process vacuum chamber (31).

4. The method of any one of the preceding claims, wherein the web material to be processed is at least one of paperboard material, thick paper and low density, bulky paper.

5. The method of any one of the preceding claims, wherein the vacuum coating is arranged to deposit a coating on the web material of a vapor deposited inorganic material, such as metal or metal oxide.

6. The method of any one of the preceding claims, further comprising forming a film on the coating of the web material to be processed by extrusion or lamination.

7. The method of any one of the preceding claims, wherein a vacuum pressure in the process vacuum chamber (31) is lower than a vacuum pressure in the auxiliary vacuum chamber (32).

8. The method of any one of the preceding claims, wherein the inlet guide path and the outlet guide path at least in parts of their extensions are separated from each other by a separation distance of less than 1 / 4 of the width of the web material, and preferably less than 1 / 10 of the width of the web material.

9. The method of any one of the preceding claims, wherein the inlet guide path and the outlet guide path are arranged so that non-coated backsides of the web material face each other.

10. The method of any one of the preceding claims, further comprising a pretreatment in the auxiliary vacuum chamber (32) and / or an intermediate vacuum chamber (33) between the auxiliary vacuum chamber (32) and the process vacuum chamber (31) for pretreatment of the web material prior to coating, said pre-treatment preferably being at least one of flame treatment, corona treatment and plasma treatment.

11. The method of any one of the preceding claims, wherein the part of the inlet guide path and the outlet guide path extensions that are separated from each other with a separation distance of less than half a width of the web material extends over at least 20% of their length extensions, and preferably over at least 50%, and most preferably over at least 70%.

12. The method of any one of the preceding claims, wherein an electric potential difference is provided between a first conducting element (329a) arranged on a side of the web material in the inlet guide path opposite to the web material of the outlet guide path and a second conducting element (329b) arranged on a side of the web material of the outlet guide path being opposite to the web material of the inlet guide path.

13. An in-line web material processing apparatus for producing a coated material (2), wherein the web material is paper or paperboard, the apparatus comprising: a process vacuum chamber (31) comprising a vacuum coating unit (5) for deposing a coating on the web material, and preferably an inorganic coating; and an auxiliary vacuum chamber (32) comprising separate or combined inlet and outlet openings (321, 323), at least the inlet opening (321) forming a passage to ambient atmospheric pressure, and a transit opening (325, 327), the transit opening (325, 327) forming a direct or indirect passageway between the auxiliary vacuum (32) chamber and the process vacuum chamber (31); wherein an inlet guide path in the auxiliary chamber (32) is arranged to guide a web material to be coated from the inlet opening (321) to the transit opening (325, 327) and an outlet guide path in the auxiliary chamber (32) is arranged to guide a coated web material from the transit opening (325, 327) to the outlet opening (323), and wherein the inlet guide path and the outlet guide path are separate from each other, wherein the inlet guide path and the outlet guide path over at least a part of their extensions are separated from each other by a separation distance of less than half a width of the web material.

14. The in-line web material processing apparatus of claim 13, wherein the inlet opening (321) and outlet opening (323) are separate openings, and preferably arranged in the vicinity of each other.

15. The in-line web material processing apparatus of claim 13 or 14, further comprising an unwinder reel holder (41) for holding a supply roll (61) of web material in ambient pressure outside said auxiliary vacuum chamber (32).

16. The in-line web material processing apparatus of any one of the claims 13-15, further comprising a rewinding reel holder (41) for holding a rewinding reel (62) forrewinding of the coated material in ambient pressure outside said auxiliary vacuum chamber (32).

17. The in-line web material processing apparatus of any one of the claims 13-16, further comprising at least one intermediate vacuum chamber (33) arranged between the auxiliary vacuum chamber (32) and the process vacuum chamber (31).

18. The in-line web material processing apparatus of any one of the claims 13-17, wherein the web material to be processed is at least one of paperboard material, thick paper and low density, bulky paper.

19. The in-line web material processing apparatus of any one of the claims 13-18, wherein the vacuum coating unit (5) is arranged to deposit a coating on the web material of a vapor deposited inorganic material, such as metal or metal oxide.

20. The in-line web material processing apparatus of any one of the claims 13-19, further comprising an extrusion or lamination unit (8) for forming a film on the coating of the web material to be processed.

21. The in-line web material processing apparatus of any one of the claims 13-20, wherein a vacuum pressure in the process vacuum chamber (31) is lower than a vacuum pressure in the auxiliary vacuum chamber (32).

22. The in-line web material processing apparatus of any one of the claims 13-21, wherein the inlet guide path and the outlet guide path at least in parts of their extensions are separated from each other by a separation distance of less than 1 / 4 of the width of the web material, and preferably less than 1 / 10 of the width of the web material.

23. The in-line web material processing apparatus of any one of the claims 13-22, wherein the inlet guide path and the outlet guide path are arranged so that non-coated backsides of the web material face each other.

24. The in-line web material processing apparatus of any one of the claims 13-23, wherein at least one, and preferably all, of the inlet, outlet and a transit openings are provided with one or more nip roller (322; 324; 326; 328), and preferably a pair of closely arranged nip rollers.

25. The in-line web material processing apparatus of any one of the claims 13-24, wherein a pair of air leading foil (322’) is arranged in the vicinity of the inlet opening (321) and external of the auxiliary vacuum chamber (32).

26. The in-line web material processing apparatus of any one of the claims 13-25, further comprising a pre-treatment station (7) arranged in the auxiliary vacuum chamber (32) and / or an intermediate vacuum chamber (33) between the auxiliary vacuum chamber (32) and the process vacuum chamber (31) for pretreatment of the web material prior to coating, said pre-treatment preferably being at least one of flame treatment, corona treatment and plasma treatment.

27. The in-line web material processing apparatus of any one of the claims 13-26, wherein the part of the inlet guide path and the outlet guide path extensions that are separated from each other with a separation distance of less than half a width of the web material extends over at least 20% of their length extensions, and preferably over at least 50%, and most preferably over at least 70%.

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