Method for processing wrapping paper for smoking articles

Abstract

The invention is related to a method for processing wrapping paper for smoking articles comprising the following steps repeated periodically: a) supplying a portion of wrapping paper designed to make a smoking article to an operative range (23) of a marking device; and b) creating a feature on the portion of wrapping paper (26) by way of the marking device. The method is characterized by a step of holding the portion of wrapping paper on a processing surface in a fixed position in the operative range by way of vacuum suction device (24) while creating the feature; wherein the wrapping paper has a weight of 10 g / m2 to 16 g / m2 and the step of creating the feature is accomplished by a marking device that is a laser marking device (12) operated with a beam energy of 1 Watt to 15 Watt.

Description

[0001] Method for processing wrapping paper for smoking articles

[0002] The invention relates to a method for processing wrapping paper for smoking articles . More speci fically, the invention relates to a method for creating a feature on a portion of wrapping paper that is used to make a smoking article .

[0003] As used herein, the term " smoking article" refers to any number of di f ferent types of articles like a cigarette in which a planar material like a wrapping paper is rolled into a tube having an elongated, hollow shape . The tube is filled or otherwise packed with a smoking substance having beneficial ef fects such as cannabis , tobacco , herbs , or some other suitable material . The tube can be cylindrical or tapered .

[0004] One end of the smoking article is ignited, which initiates a slow combustion of the product and the tube material . A user inhales the smoke generated by the combustion of the product through the other end of the smoking article . A smoking article provides an ef ficient mechanism to deliver pharmaceutical constituents o f the filler material via an aerosol that is breathed in and absorbed through the lungs of the user .

[0005] To meet the wide range of needs of manufacturers of smoking articles , the webs of paper are often processed before being used . To identi fy the source of the wrapping paper of for marketing purposes , the wrapping paper may contain features like a trademark or brand name . Further, the wrapping paper may contain other types of features like information about its use , origin or other features that helps the user to recogni ze the product among others . Features can also be decorative

[0006] A24 037 E P / 04 . 03 . 2025 / features by way of which the user can di f ferentiate smoking articles or counterfeiting is made di f ficult .

[0007] Applying a watermark in the form a subtle image permanently impressed into the wrapping paper before or during the manufacturing process of the smoking material is a known method to achieve needs of manufacturers of smoking articles discussed above . A watermark is made by impressing a roller embossed with a pattern onto the paper during manufacturing . There are two ways in which a watermark can be made . Firstly, in an online process when the paper itsel f is being manufactured . While the result may be much better it is unreasonable for smaller brands to consider this option as the setup costs and quantities required are restrictive because of the initial costs . The other option is an of fline process where the watermark is embossed on the paper after the paper is produced . This option has reasonable costs for smaller batch si ze but there is still an incompressible lead time required to produce a watermark roller that limits the flexibility in case the watermark must be amended, or a di f ferent watermark is required . For example , CN106042692A discloses a method of manufacturing smoking article wrappers with a watermark .

[0008] Alternatively, features can be printed with chemical substances like ink on the wrapping paper . For example , W02006 / 029723A1 discloses a method of printing smoking article wrappers . However, inks suitable for this purpose require careful development and available in a limited variety because of the risk to produce undesirable substances during combustion for the user .

[0009] Lasers can also be used in paper material processing, wherein

[0010] A24 037 E P / 04 . 03 . 2025 the energy of a laser beam interacts with the paper material to trans form . Each trans formation is controlled by regulating the wavelength, power, duty cycle and repetition rate of the laser beam . For example , WO98 / 35096 discloses a method of processing paper where the laser beam burns the paper in a small area, and thus causes dark color discoloration at defined locations . However, certain pigments are provided in the paper or in the coating on the paper to obtain a good mark through controlled color changes , and such controlled colors are often not allowed due to legal requirements for smoking products . Further, such processes are disclosed for paper having a weight of at least 70 g / m2 because lighter paper would burn under the ef fect of the laser beam . Such a method cannot be used for smoking article wrappers .

[0011] WO2023 / 041586A1 discloses a smoking article wrapper comprising at least one layer of cellulosic material having a thickness of at least 35 micrometers and a tensile strength of at least 25 N / 15 mm . Such basis weight is particularly chosen for mouthpiece wrappers which are those most subj ect to bearing design features and indicia . The wrapper material comprises an indicium etched over a determined depth less than its thickness . Further, a method of manufacturing such a smoking article wrapper is disclosed, the method comprising a step of etching an indicium into the wrapper by evaporating wrapper material with a laser beam according to indicium vector lines over a determined depth less than the thickness of the cellulosic material layer . The laser source has a nominal power of about 20 Watt to 100 Watt . In this method, a continuous web of wrapper material is dragged from a feeding station and fed through a laser-etching station by means of two pairs of

[0012] A24 037 E P / 04 . 03 . 2025 rollers arranged respectively ahead and behind an etching area along a feeding direction in the laser-etching station . Both rollers of a pair are in contact respectively with one of the two surfaces of the wrapper material and rotate with an identical angular speed to ensure homogenous friction over the web of wrapper material and constant linear speed thereof through the laser-etching station .

[0013] US 6064032A discloses an apparatus for manipulating a web of tipping paper in a filter cigarette making machine . The web is advanced lengthwise by rollers which cause it to advance over a rotary drum-shaped suction conveyor . The web is subdivided into discrete uniting bands and / or is perforated by resorting to sources of coherent radiation . Each source is associated with a control unit which initiates the emission of shortlasting flashes of coherent radiation . Such radiation is caused to impinge upon a di f fractive focusing lens which focuses coherent radiation upon one or more masks having openings used to sever the web along transversely extending linear zones and / or to provide the web with desired arrays of perforations .

[0014] The aim of this invention is to provide a method for processing a portion of wrapping paper used to make smoking articles that overcomes the above mentioned drawbacks of the prior art . Further, the method should not slow down the burn rate or af fect the evenness of burning of the wrapping paper .

[0015] Description of the invention

[0016] The obj ect of the present invention is to provide a method for processing a portion of wrapping paper used to make smoking

[0017] A24 037 E P / 04 . 03 . 2025 articles that overcomes the above mentioned drawbacks of the prior art . Further, the method should not slow down the burn rate or af fect the evennes s of burning of the wrapping paper .

[0018] The obj ect of the present invention is achieved by the method for processing a portion of wrapping paper for smoking articles disclosed in claim 1 . Preferred embodiments are disclosed in the dependent claims .

[0019] A method for processing wrapping paper for smoking articles is disclosed comprising the following steps repeated periodically : a ) supplying a portion of wrapping paper designed to make a smoking article to an operative range of a marking device ; and b ) creating a feature on the portion of wrapping paper by way of the marking device . In other words , the method for processing wrapping paper is in the form of a method for marking wrapping paper for smoking articles .

[0020] In the meaning of the present invention, a portion of wrapping paper can be in the form of a region of a web or of a roll of wrapping paper, wherein the web or the roll can be cut in the form of single sheets , usually rectangular, of varying si zes , that are used to make a smoking article . The portion of wrapping paper can be in the form of a region of a single sheet that is designed to make a single smoking article . The region can extend to the whole sheet .

[0021] The feature to be engraved can be any kind of marking applied to the wrapping paper like a trademark, a brand name , information about its use , its origin or other features that helps the user to recogni ze the product among others . The features can also be decorative to di f ferentiate smoking articles from others or made to render counterfeiting

[0022] A24 037 E P / 04 . 03 . 2025 di f ficult . Features can generally be in the form of texts or contour lines as well as full-surface areas .

[0023] Wrapping paper for smoking articles can be made from thin and lightweight fibers such as flax, hemp, sisal , rice straw, and esparto . The paper is available in the form of a web or a roll , or it can be cut in the form of sheets , usually rectangular, of varying si zes . For the assembly in the form of a tube , the sheet has a narrow strip of glue along one long edge . The wrapping paper may be transparent , colored and / or flavored .

[0024] According to the invention, the method further comprises a step of holding the portion of wrapping paper on a processing surface in a fixed position in the operative range by way of vacuum suction device while creating the feature , wherein the wrapping paper has a weight of 10 g / m2 to 16 g / m2 and the step of creating the feature is accomplished by a marking device that is a laser marking device operated with a beam energy of 1 Watt to 15 Watt .

[0025] To maintain the wrapping paper in a fixed position by way of vacuum suction during laser processing to engrave the wrapping paper is an important process parameter because the heat generated can cause fibers of the wrapping paper to expand or contract . However, due to the thinness and porosity of the wrapping paper in the range of weight mentioned, it has been found that vacuum can pass at least partially through layers of fibers in the structure of the wrapping paper and immobili ze the fibers in a fixed position during processing . In contrary, for heavier papers or films , only the side facing the vacuum suction device is af fected by vacuum suction . By fixing the fibers during processing, the fibers remain in their original

[0026] A24 037 E P / 04 . 03 . 2025 position upon cooling, ensuring that the wrapping paper retains its shape after cooling .

[0027] Advantageously, holding the portion of wrapping paper in a fixed position avoids deformation of the paper fibers that can cause curling of the wrapping paper under the ef fect of the heat generated by the laser beam . Indeed, curled wrapping paper used to manufacture smoking articles result in rolls that present an irregular profile or weaknesses at the j unction between the glued borders of the wrapping paper . Such deformation can also result in weakness areas when the structure of the paper fibers is modi fied locally and increase the risk of tearing when it is manipulated .

[0028] Wrapping paper is a very thin and light paper having a weight in the range of 10 g / m2 to 16 g / m2 that can burn under the ef fect of heat . Wrapping paper having a weight of 10 g / m2 to 16 g / m2 has a thickness of less than 25 micrometer . For this reason, on the one hand, the beam energy of the laser must be set at a low level so that the wrapping will not catch fire . At the same time , the wrapping paper must not be perforated by the laser beam to avoid an increase in the porosity of the wrapping paper that would cause an increase in the combustion speed of the smoking product by allowing the entry of additional air .

[0029] Further, the wrapping paper must not be perforated by the laser beam to prevent the wrapping paper from tearing during the subsequent manufacturing steps . Laser perforation can form weakness areas and must also be avoided to limit the risk of tearing when a consumer manipulates the wrapping paper . On the other hand, the beam energy of the laser must be high enough

[0030] A24 037 E P / 04 . 03 . 2025 to leave a mark on the wrapping paper to create the feature desired . In the range of 1 Watt to 15 Watt , a broad range of marking depths for the weight of wrapping papers considered can be achieved to form various shades in the feature created . A range o f less 10 Watt has still a wide range of application including for example features in the form of texts or contour lines as well as full-surface areas .

[0031] In comparison, paper with 90 g / m2 to 120 g / m2 is typically used for letter or books and even heavier ones for cardboard for which laser marking processes are disclosed in the prior art . At least for these reasons , developing a process ful filling all the precited technical requirements for a paper five to ten times lighter involves a challenging technical setting that goes beyond a simple optimi zation of parameters .

[0032] Wrapping paper having a weight in the range 10 g / m2 to 16 g / m2 can be used to be rolled in the form of a tube for filling with a smoking substance such as tobacco or some other suitable material . Other suitable material can be substance having beneficial ef fects such as cannabis , tobacco , herbs and mixture thereof . The tube has an elongated, hollow shape .

[0033] In a further preferred embodiment , the laser marking device is operated with a beam energy of 5 Watt to approximately 12 Watt . Such ranges are suitable for a wide range of wrapping papers for smoking articles in the range of weight mentioned above . Experiments have shown that these conditions optimi ze the creation of the feature . In a preferred embodiment , the laser marking device is operated with a beam energy of 10 Watt to 15 Watt for thin papers in the range 10 g / m2 to 28 g / m2 . A beam

[0034] A24 037 E P / 04 . 03 . 2025 energy of less than 10 Watt is also preferred for a wide range of features .

[0035] It is also possible to operate the laser marking device is operated with a beam energy of less than 1 Watt for very thin markings .

[0036] The beam energy can be chosen in function of di f ferent parameters , for example the type of feature that must be engraved . For features in the form of text , higher beam energy can be chosen than for engraving full-surface areas that heat up due to the repeated and neighboring passages of the laser beam .

[0037] In a preferred embodiment , the step of creating the feature is performed under a controlled relative humidity ranging from 40% to 70% and a temperature between 15 ° C and 30 ° C, preferably 45% to 60% and a temperature between 18 ° C and 25 ° C . The control of the relative humidity further improves the reproducibility of the engraving of the feature because the properties of the wrapping paper can be kept within a range corresponding to the optimi zed marking conditions .

[0038] In a preferred embodiment , the wrapping paper has a weight of 10 g / m2 to 14 g / m2 to cover a wide range of paper weight used for smoking articles . Wrapping paper having a weight of 10 g / m2 to 14 g / m2 has a thickness of less than 22 micrometer .

[0039] In a preferred embodiment , the laser marking device is a CO2- laser that are available at low costs . The use of laser has the advantage that the process can be easily and nearly instantly adapted to produce a di f ferent feature or amend an existing one . The energy of the CO2-laser beam can be easily

[0040] A24 037 E P / 04 . 03 . 2025 absorbed by the fibers comprised in the wrapping paper. The laser beam heats the material directly in its path, causing it to vaporize at least partially leaving a mark. The CO2-laser produces a beam of infrared light with the principal wavelength bands centering on 9.6 and 10.6 micrometers (pm) . Other types of laser marking device can also be used, as long as laser beam energy and laser beam pulse in the ranges specified herein can be achieved.

[0041] In a preferred embodiment, the laser marking device is operated with a laser beam pulse having a frequency of less than 100 kHz. The range defined result in a beam energy that avoids perforation of the wrapping paper and at the same time avoids that it catches fire. In a more preferred embodiment, the frequency is chosen between 20 kHz to 60 kHz. In a more preferred embodiment, the frequency is chosen between 30 kHz to 60 kHz. Experiments have shown that these conditions optimize the creation of the feature.

[0042] In a preferred embodiment, the larger dimension of the portion of wrapping paper used to make the smoking article is 5 cm to 15 cm, preferably 7 cm to 10 cm, more preferably 8 cm. This allows marking of most typical wrapping paper sheets for smoking articles that come in several sizes and range typically from 2.75 x 1.4 inches to 4 x 2 inches (approximately 6.3 cm x 3.5cm to 10 cm x 5 cm) . Smaller size can also be treated with precision, for example 2.0 cm x 5.0 cm.

[0043] In a preferred embodiment, the vacuum suction device is in the form of a suction pad formed in the processing surface, that is preferably a table, and connected to a vacuum source that is operated in a synchronized manner with a supply rate of the

[0044] A24037EP / 04.03.2025 portion of wrapping paper to the operative range . The embodiment has the advantage that standard components can be used that allow an economical design .

[0045] In a preferred embodiment , the vacuum suction device is in the form of a conveyor belt which belt forms the processing surface , the conveyor belt closing at least approximately hermetically a depression chamber connected to a vacuum source . The conveyor belt being operated in a synchroni zed manner with the supply rate of the portion of wrapping paper, wherein the belt has openings to allow suction of the wrapping paper against the belt . At the end of the belt , as seen in a direction of advance of the wrapping paper, the wrapping paper is released from the vacuum suction to the belt by way of its movement in the direction of advance . The embodiment allows processing of larger quantities of wrapping paper with less interruption .

[0046] In a preferred embodiment , the portion of wrapping paper is part of a web or a roll of wrapping paper that is fed to the operative range of the laser marking device , preferably at a supply rate of 100 cm / s to 300 cm / s , more preferably 200 cm / s . In this embodiment , the web of wrapping paper can be provided by a wrapping paper supply unit arranged upstream in the form of a rol l of unmarked wrapping paper that is unrolled and fed to the operative range of the laser marking device . After the step of creating the feature , the wrapping paper can be stored in a wrapping paper storing unit arranged downstream in which the marked wrapping paper is rolled and stored for future use . Alternatively, after the step of creating the feature , the marked wrapping paper can be further processed in a processing unit arranged downstream of the laser marking device , for

[0047] A24 037 E P / 04 . 03 . 2025 example for cutting sheet of wrapping paper designed to make smoking articles .

[0048] In a preferred embodiment , the portion of wrapping paper is a sheet of wrapping paper that is fed to the operative range of the laser marking device , preferably at a supply rate of 5 sheet / s to 30 sheet / s , more preferably 20 sheet / s . Preferably the sheet is designed to be used for making one smoking article . In this embodiment , sheets of wrapping paper, for example cut to the dimensions required to manufacture a smoking article , can be supplied one by one or in groups to the operative range of the laser marking device by a transport unit arranged upstream . After the step of creating the feature , the marked sheets of wrapping paper can be further processed in a processing unit arranged downstream of the laser marking device , for example by forming the sheets of wrapping paper in the form of tubes designed to make smoking articles .

[0049] In a preferred embodiment , the area covered by the feature extends over more than 50% of the portion of wrapping paper used to make the smoking article .

[0050] In a preferred embodiment , the laser marking device is operated with a marking speed of more than 1200 mm / s . Preferably the marking speed is between 1500 mm / s and 3500 mm / s , more preferably between 2000 mm / s and 3000 mm / s . In combination with parameters of operation of the laser marking device , in particular the beam pulse and beam energy mentioned above , the marking speed of more than 1200 mm / s limits the risks of perforating the wrapping paper . Higher speeds in the range between 1500 mm / s and 3500 mm / s allow for a broad range of

[0051] A24 037 E P / 04 . 03 . 2025 marking depths in the wrapping paper that can be used to form various shades in the feature created .

[0052] The laser marking device can be operated with a marking speed between 1500 mm / s and 3500 mm / s and a beam energy of 5 Watt to less than 20 Watt as well as a laser beam pulse having a frequency between 20 kHz to 60 kHz .

[0053] In a preferred embodiment , the laser marking device is operated with a marking speed between 1500 mm / s and 3500 mm / s and a beam energy of 1 Watt to 15 Watt as well as a laser beam pulse having a frequency between 20 kHz to 60 kHz . The combination of parameter defines a range of parameters that is suitable for the marking of most wrapping paper for smoking articles in the range of weight available on the market .

[0054] In a preferred embodiment , the step of creating a feature is followed by a step of cutting the wrapping paper . Preferably cutting the wrapping paper is done using the same laser marking device . This embodiment has the advantage that the same tool can be used for engraving the features and cutting the wrapping paper in sheets while the wrapping paper is maintained in a fixed position in the operative range . Besides being economical , it improves the quality of the sheets that do not curled under the ef fect of the heat of the laser beam .

[0055] In a preferred embodiment , the laser marking device is operated for cutting the wrapping paper with a marking speed between 1500 mm / s and 3500 mm / s , preferably 2000 mm / s to 3000 mm / s , a beam energy of 40 Watt to 60 Watt and a laser beam pulse having a frequency between 20 kHz to 60 kHz . The combination of parameter defines a range of parameters that is suitable for

[0056] A24 037 E P / 04 . 03 . 2025 the cutting of most wrapping paper for smoking articles in the range of weight available on the market .

[0057] In a preferred embodiment , the feature is a barcode that is engraved according to any one of the previous embodiments of the method, preferably comprising bars of 50 micrometer to 800 micrometer, more preferably 100 micrometer to 500 micrometer . The width reduction of the bars is limited on the one hand by the laser beam spot si ze as well as the interaction between the laser and the fibers of the paper that lead to blurred edges and barcodes that are not reliably readable . On the other hand, an increase of the width of the bars leads to heating of the wrapping paper during engraving and a risk to burn the wrapping paper . To limit deformation of the barcode on the smoking articles , barcodes can be engraved in the longitudinal direction of the smoking article . The range of 100 micrometer to 500 micrometer provides an optimal trade-of f between these constraints and can be implemented by the method disclosed .

[0058] In a preferred embodiment , the feature is a QR-code that is engraved according to any one of the previous embodiments of the method, preferably having a si ze of 4x4 mm to 10x10 mm, more preferably 5x5 mm to 7x7mm . The si ze reduction of the QR- codes is limited on the one hand by the interaction between the laser and the fibers of the paper that lead to blurred edges and QR-codes that are not reliably readable . On the other hand, an increase of the si ze of the QR-codes leads also to QR-codes that are not reliably readable because they are curved as the paper is deformed to form smoking articles . The range of 5x5 mm to 7x7 mm provides an optimal trade-of f between these constraints and can be implemented by the method disclosed .

[0059] A24 037 E P / 04 . 03 . 2025 Description of the figures

[0060] Further advantages and features of the invention are described by way of illustrative embodiments, which are explained with reference to the following figure.

[0061] In this purely schematic feature,

[0062] - Fig. 1 shows a cross section of an embodiment of a marking module that can be used to implement the method according to the invention in an installation to manufacture smoking articles ,

[0063] - Fig. 2 shows a cross section of a further embodiment of the marking module; and

[0064] - Fig. 3 shows engraved features on a wrapping paper of 14 g / cm2 and 4.5 to 7.0 Watt;

[0065] - Fig. 4 shows engraved features on a wrapping paper of 14 g / cm2 and 20 Watt;

[0066] - Fig. 5 shows engraved features on a wrapping paper of 40 g / cm2 and 4.5 to 7.0 Watt;

[0067] - Fig. 6 shows engraved features on a wrapping paper of 40 g / cm2 and 20 Watt;

[0068] - Fig. 7 shows engraved features on a wrapping paper of 14 g / cm2 without suction vacuum;

[0069] - Fig . 8 shows engraved features on a wrapping paper of 14 g / cm2 with suction vacuum;

[0070] A24037EP / 04.03.2025 - Fig . 9 shows engraved features on a wrapping paper of 14 g / cm2 with suction vacuum;

[0071] - Fig . 10 shows engraved features on a wrapping paper of 14 g / cm2 without suction vacuum;

[0072] - Fig . 11 shows engraved features on a wrapping paper of 14 g / cm2 and a humidity above 65% ;

[0073] - Fig . 12 shows engraved features on a wrapping paper of 14 g / cm2 and a humidity between 50% and 60% ; and

[0074] - Fig . 13 shows a wrapping paper of 14 g / cm2 without suction vacuum .

[0075] To create a feature on a portion of wrapping paper, a marking module 10 is provided that comprises a marking device in the form of a laser marking device 12 , a processing chamber 14 and a vacuum source 16 which is represented schematically only in Fig . 1 .

[0076] The laser marking device 12 comprises a CO2-laser 18 which beam 19 defines a longitudinal direction of the marking module . The CO2-laser comprises a beam exit window 20 that is connected to the processing chamber 14 to allow the proj ection of the beam in the processing chamber . In the present embodiment , the longitudinal axis is vertical which is not limiting . An inclined or in particular a hori zontal longitudinal axis is also possible .

[0077] Further, the processing chamber 14 comprises a processing surface in the form of a table 22 extending in a plane facing the beam exit window 20 , wherein the plane extends substantially perpendicular to the longitudinal direction in

[0078] A24 037 E P / 04 . 03 . 2025 the present embodiment . The processing table can also be facing the beam exit window at an angle di f ferent to 90 ° as long as the arrangement allows laser marking with the required quality .

[0079] The laser marking device defines an operative range 23 on the processing table 22 in which operative range wrapping paper can be processed . The operative range and its si ze are defined by the limits of the processing table that can be scanned by the laser beam 19 when it is in operation .

[0080] The processing table 22 comprises a vacuum suction device in the form of a vacuum suction pad 24 arranged in the operative range 23 and designed to hold wrapping paper in a fixed position during the creation of a feature to avoid deformation like curling of the wrapping paper under the ef fect of the heat generated by the CO2-laser beam . For this purpose , the vacuum suction pad is connected to the vacuum source 16 . In Fig . 1 , the portion of wrapping paper is a sheet 26 of wrapping paper is held over the suction pad 24 . A temperature and humidity controller 28 , represented schematically only in Fig . 1 , is connected to the processing chamber 14 to monitor and maintain the relative humidity in the appropriate range for an optimi zed marking of the sheet of wrapping paper .

[0081] In addition, the processing chamber comprises an inlet 30 through which unmarked sheets are supplied to the processing table 22 and an outlet 32 through which marked sheets exit the processing chamber for a further processing in a downstream processing unit . The corresponding directions are indicated by arrows .

[0082] In the embodiments considered in the present invention, the wrapping paper has a weight of 10 g / m2 to 16 g / m2 .

[0083] A24 037 E P / 04 . 03 . 2025 The process is performed under a controlled relative humidity ranging from 40% to 70% and a temperature between 15 ° C and 30 ° C .

[0084] In operation, for processing wrapping paper for smoking articles , a portion of wrapping paper like the sheet 26 designed to make a smoking article is supplied to the operative range 23 of a marking device , here the CO2-laser 18 . Then, a feature is created on the sheet 26 by way of the CO2-laser . Further, the step of creating the feature is accomplished by the CO2-laser that is operated with a beam energy between 1 Watt to 15 Watt , typically 10 Watt for most wrapping papers . It is also possible to reduce the beam energy to intensities lower than 1 Watt for very thin markings . The laser beam pulse has a frequency of less than 100 kHz , usually 20 kHz to 60 kHz for most wrapping papers available on the market .

[0085] Further, the laser marking device can be operated with a marking speed of more than 1200 mm / s . Preferably, the marking speed is between 1500 mm / s and 3500 mm / s .

[0086] The laser marking device can be operated for the creation of a feature with a preferred combination of parameters such as a marking speed between 1500 mm / s and 3500 mm / s and a beam energy of between 1 Watt to 15 Watt as well as a laser beam pulse having a frequency between 20 kHz to 60 kHz . The combination defines a range of parameters that is suitable for the marking of most wrapping paper for smoking articles in the range of weight available on the market .

[0087] At the same time , the sheet 26 of wrapping paper is held in a fixed position in the operative range 23 by way of a vacuum

[0088] A24 037 E P / 04 . 03 . 2025 suction device in the form of a suction pad 24 while creating the feature .

[0089] The embodiment of Fig . 2 is assembled in a similar manner as the embodiment of Fig . 1 . Same features having the same functions bear the same reference numbers and are not described again for Fig . 2 .

[0090] The main di f ferentiating feature in the embodiment of Fig . 2 is the vacuum suction device that is the form of a conveyor belt 40 which belt 41 forms the processing surface , wherein the conveyor belt closes at least approximately hermetically a depression chamber 42 connected to a vacuum source . In addition, a seal 44 is provided to keep the vacuum below a required suction threshold . The conveyor belt i s operated by a driving unit 45 in a synchroni zed manner with the supply rate of the portion of wrapping paper . For the suction of the wrapping paper, the belt 41 has openings 43 to allow suction of the wrapping paper against the belt . At the end of the belt , as seen in a direction of advance of the wrapping paper, the wrapping paper is released from the vacuum suction to the belt by way of its movement in the direction of advance .

[0091] The laser marking device can be also operated for cutting the wrapping paper after the step of creation of the feature , wherein the marking speed is between 1500 mm / s and 3500 mm / s , preferably 2000 mm / s to 3000 mm / s , the beam energy is between 40 Watt to 60 Watt and the laser beam pulse has a frequency between 20 kHz to 60 kHz . Concretely, the combination of a marking speed of 2000 mm / s and a beam energy of 60 Watt as well as a laser beam pulse having a frequency of 50 kHz covers

[0092] A24 037 E P / 04 . 03 . 2025 a broad range of wrapping papers in the range 10 g / m2 to 40 g / m2 .

[0093] Experiments

[0094] Parameters comprising laser beam energy for engraving lines and contours or full-surfaces , presence of vacuum to hold the wrapping paper and humidity range have been tested to define the optimal conditions for engraving wrapping paper .

[0095] All tests listed in the table below have been performed with CO2-laser having a laser beam spot si ze of 50 micrometer, a beam pulse having a frequency of 50 kHz and a marking speed of 1500 mm / s .

[0096] Laser beam energy :

[0097] Figures 3 , 4 , 5 and 6 illustrate the di f ferences between engraving wrapping paper in the range of 10 g / m2 to 16 g / m2 as in the present invention and paper used for a mouthpiece element of typically at least 34 g / cm2 as processed in WO2023 / 041586A1 . The di f ference between engraving features in the form of lines and contours like in the word "Accelerant" used or full-surfaces like in a QR-code is also illustrated .

[0098] A24 037 E P / 04 . 03 . 2025

[0099]

[0100] A24037EP / 04.03.2025 In Fig . 6 , paper used for a mouthpiece having a density of about 40 g / m2 and a thickness of about 55 micrometer is engraved with a laser beam energy of 20 Watt as disclosed in WO2023 / 041586A1 where it ranges from a minimum of about 20 Watt to 100 Watt . The QR-code engraved in the paper having a density of 40 g / m2 is engraved in a manner that can be read by a QR-code reader .

[0101] Starting from the engraving conditions of Fig . 6 with 20 Watt , a reduction of the laser beam energy quickly leads to engraving conditions that are not usable for a paper having a density of 40 g / m2 as can be seen in Fig . 5 where the barcode is barely visible in the upper right quarter of the figure after engraving at 7 . 0 Watt .

[0102] For the wrapping paper having a density of 14 g / cm2 within the range of the present invention and a thickness of about 20 micrometer, a laser beam intensity of 20 Watt burns holes in the wrapping paper, rendering it unusable as can be seen in Fig . 4 in which at least 3 corner squares as well as most of the central portion of the QR-code are through holes . On the same figure , it is also clear that the text engraved at 20 Watt presents defects in the form of burnt places and holes visible as black spots that result in a poor quality of engraving . Only after a reduction to 4 . 5 Watt for the engraving of full-surfaces of the barcode can a readable barcode be achieved as illustrated in Fig . 3 in which the contours , line and full-surface zone present a uni form light grey color . Still referring to the same figure , it is shown that text can be engraved at 7 . 0 Watt with the quality required for marketing purposes .

[0103] A24 037 E P / 04 . 03 . 2025 A higher energy is acceptable for text because the engraving positions are farther from each other than in the case of fullsurface engraving in which contiguous sectors must be processed, causing an increased heating of the wrapping paper .

[0104] The set of experiments shows that a fine tuning of laser beam energy in a range of 4 . 5 Watt to 7 . 0 Watt is necessary to obtain appropriate results for text and full-surface features , respectively . Small variations of the laser beam energy up to 15 Watt still allow an acceptable engraving quality for most of the features . It also shows the strong di f ference in the engraving quality for laser beam energy and wrapping paper weight for ranges used in the present invention and those disclosed in WO2023 / 041586A1 .

[0105] In the previous four experiments , the wrapping paper was held in a fixed position in the operative range of the laser source by way of a vacuum suction device in the form of a suction pad while creating the features . The activation of the vacuum suction pad during processing plays also an important role as shown in Fig . 7 , 8 , 9 and 10 below .

[0106] Vacuum and suction device :

[0107] The wrapping paper is maintained in a fixed position by way of the vacuum suction during laser processing in Fig . 8 and fig . 9 in which the contours , line and full-surface zone present a mostly uni form light grey color . Heat generated by the laser beam cause fibers of the wrapping paper to expand . However, in the range of paper weight mentioned for the present invention, vacuum can pass at least partially through layers of fibers of the wrapping paper and immobili ze the fibers in a fixed position during processing . At the same time , there is at least

[0108] A24 037 E P / 04 . 03 . 2025 a partial evacuation of the heat caused by the engraving . Both the paper weight and the presence of the suction device have a synergistic ef fect .

[0109] For the same processing conditions but without vacuum, poor engraving quality is obtained as shown in Fig . 7 and Fig . 10 in which defects in the form of burnt places and holes are visible as black spots . Arrows have been added to point to some of the defects visible .

[0110] A further aspect of the poor engraving quality in the absence of vacuum is visible in Fig . 7 in which the central portion of the QR-code is not sharp enough to be read . During the engraving process deformation of the paper fibers caused local curling of the wrapping paper under the ef fect of the heat generated by the laser beam . As a result , the wrapping paper does not lie flat anymore while it is exposed to the action of laser beam and straight lines of the feature are engraved as deformed, curved lines . The deformation of a strip of wrapping paper is best illustrated in Fig . 13 in which vertical lines of dots extending in the direction o f the arrows at the bottom of the picture have been drawn . In the absence of vacuum suction, the deformation of the wrapper paper in a free state under the ef fect of the tension of the fibers of the wrapping paper is visible : the left hal f of the vertical lines were drawn in a valley region and about the right halves of the vertical lines were drawn in a ridge region formed by the strip . The engraving of features with precise contours consequently not possible in the absence of vacuum for the type of wrapping paper cons idered .

[0111] A24 037 E P / 04 . 03 . 2025 In contrary, for heavier papers , typically 40 g / m2 of the present experiment , the fibers remain in their original position upon cooling and the wrapping paper retains mostly its shape even in the absence of vacuum suction during heating while engraving at least up to laser beam energy of 20 Watt and during cooling .

[0112] Humidity :

[0113] In the previous experiments , the wrapping paper was held under a humidity range between 55% + / -5% in the operative range of the laser source by a humidity controller connected to the processing chamber at a temperature of about 21 ° C + / -3 ° C .

[0114] The ef fect of an increase of the humidity from a value in the range between 50% and 60% to a value above 65% is visible by comparison of the engraving results in Fig . 12 and Fig . 11 , respectively . The increased humidity present during the engraving of Fig . 11 results in a less uni form and bleached light grey color of the feature .

[0115] List of reference signs marking module 10 laser marking device 12 processing chamber 14 vacuum source 16

[0116] CO2-laser 18 laser beam 19 beam exit window 20

[0117] A24 037 E P / 04 . 03 . 2025 processing table 22 operative range 23 vacuum suction pad 24 sheet of wrapping paper 26 temperature and humidity controller 28 inlet 30 outlet 32 conveyor belt 40 belt 41 depression chamber 42 openings 43 seal 44 driving unit 45

[0118] A24 037 E P / 04 . 03 . 2025

Claims

Claims1. Method for processing wrapping paper for smoking articles comprising the following steps repeated periodically: a) supplying a portion of wrapping paper designed to make a smoking article to an operative range (23) of a marking device ; b) creating a feature on the portion of wrapping paper (26) by way of the marking device; characterized by a step of holding the portion of wrapping paper on a processing surface in a fixed position in the operative range by way of vacuum suction device while creating the feature; wherein the wrapping paper has a weight of 10 g / m2 to 16 g / m2 and the step of creating the feature is accomplished by a marking device that is a laser marking device (12) operated with a beam energy of 1 Watt to 15 Watt.

2. Method according to claim 1, characterized in that the step of creating the feature is performed under a controlled relative humidity ranging from 40% to 70% and a temperature between 15°C and 30°C, preferably 45% to 60% and a temperature between 18°C and 25°C.

3. Method according to claim 1 or 2, characterized in that the wrapping paper has a weight of 10 g / m2 to 14 g / m2.

4. Method according to any of the preceding claims, characterized in that the wrapping paper has a thickness of less than 25 micrometer.

5. Method according to any of the preceding claims, characterized in that the laser marking device is operatedA24037EP / 04.03.2025with a laser beam pulse having a frequency of less than 100 kHz, preferably between 20 kHz to 60 kHz.

6. Method according to any of the preceding claims, characterized in that the larger dimension of the portion of wrapping paper used to make the smoking article is 5 cm to 15 cm, preferably 7 cm to 10 cm, more preferably 8 cm.

7. Method according to any of the preceding claims 1 to 6, characterized in that the vacuum suction device is in the form of a suction pad (24) formed in the processing surface, that is preferably a table (22) , and connected to a vacuum source (16) that is operated in a synchronized manner with a supply rate of the portion of wrapping paper to the operative range.

8. Method according to any of the preceding claims 1 to 7, characterized in that the portion of wrapping paper is part of a web or a roll of wrapping paper that is fed to the operative range of the laser marking device, preferably at a supply rate of 100 cm / s to 300 cm / s, more preferably 200 cm / s.

9. Method according to any of the preceding claims 1 to 7, characterized in that the portion of wrapping paper is a sheet of wrapping paper that is fed to the operative range of the laser marking device, preferably at a supply rate of 5 sheet / s to 30 sheet / s, more preferably 20 sheet / s.

10. Method according to any of the preceding claims 1 to 6, characterized in that the vacuum suction device is in the form of a conveyor belt (24) which belt forms theA24037EP / 04.03.2025processing surface, the conveyor belt closing at least approximately hermetically a depression chamber connected to a vacuum source (16) , the conveyor belt being operated in a synchronized manner with the supply rate of the portion of wrapping paper, wherein the belt has openings to allow suction of the wrapping paper against the belt.

11. Method according to claim 10, characterized in that the portion of wrapping paper is part of a web or a roll of wrapping paper that is fed to the operative range of the laser marking device, preferably at a supply rate of 100 cm / s to 300 cm / s, more preferably 200 cm / s .

12. Method according to any of the preceding claims, characterized in that the laser marking device (12) is operated with a beam energy of 5 Watt to approximately 12 Watt, preferably less than 10 Watt .

13. Method according to any of the preceding claims, characterized in that the laser marking device (12) is operated with a marking speed of more than 1200 mm / s, preferably between 1500 mm / s and 3500 mm / s.

14. Method according to any one of claims 1 to 13, characterized in that the feature is a barcode, preferably comprising bars of 50 micrometer to 600 micrometer, more preferably 100 micrometer to 300 micrometer.

15. Method according to any one of claims 1 to 13, characterized in that the feature is a QR-code, preferably having a size of 4x4 mm to 10x10 mm, more preferably 5x5 mm to 7x7mm.A24037EP / 04.03.2025

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