Method and apparatus for pretreating the surface of containers, such as plastic, glass or metal containers, before printing.

Abstract

The invention relates to a method for pretreating a surface of containers (2), such as plastic, glass or metal containers, before printing, such as digital printing, wherein the method involves passing containers past at least one radiation source (3, 4, 5), such as an excimer laser emitting vacuum ultraviolet radiation, and irradiating at least a part (8) of the surface of the containers with at least a part of the VUV radiation.The invention further relates to a device for pretreating a surface of containers (2), such as plastic, glass or metal containers, before printing, such as digital printing, wherein the device comprises at least one radiation source (3, 4, 5), such as an excimer laser, for emitting vacuum ultraviolet radiation and a transport device (10) for moving containers past the at least one radiation source for irradiating at least a part (8) of the surface of the containers with at least a part of the VUV radiation.

Description

[0001] The invention relates to a method and device for pretreating a surface of containers, such as plastic, glass or metal containers, before printing according to the independent claims. State of the art

[0002] It is known to pretreat glass bottles for a subsequent printing process by combining a flame treatment with subsequent silanization. This pretreatment can produce a cleaned and active surface on the glass bottle with a modified surface tension and a silicate layer, which can ensure good adhesion of the print.

[0003] During flame silanization, crystalline silicon oxide enters the process air as dust, which may require removal from the exhaust air. For example, a filtered extraction system combined with a water mist / bath can be used to bind the dust particles.

[0004] Pretreatment can involve high energy consumption from gas and electricity. The heat energy that can be absorbed by the glass bottles during flame treatment and silanization must be removed from the glass bottles before further processing. This can be achieved through active cooling, for example, in a cooling tunnel, which can take up approximately one-third of the total length of the pretreatment plant. Task

[0005] The object of the invention is to provide a method and a device for pretreating a surface of containers, such as plastic, glass or metal containers, before printing, which can enable energy and media efficient pretreatment. Solution

[0006] This object is achieved by the method and device for pretreating a surface of containers, such as plastic, glass, or metal containers, prior to printing according to the independent claims. Further embodiments are disclosed in the subclaims.

[0007] The method according to the invention for pretreating a surface of containers, such as plastic, glass or metal containers, prior to printing, such as digital printing, comprises passing containers past at least one radiation source, such as an excimer laser, which emits vacuum ultraviolet radiation, VUV radiation, and irradiating at least a portion of the surface of the containers with at least a portion of the VUV radiation.

[0008] The method can be carried out using the device described below.

[0009] The glass containers can include surface finishes such as hot-end coating (HEC) and cold-end coating (CEC).

[0010] By pretreating at least part of the container's surface, subsequent printing can be more efficient. A higher polar character can lead to a higher surface energy and can affect the contact angle. The higher surface energy can result in better surface wettability.

[0011] Since VUV radiation can be absorbed by the oxygen in the ambient air, it may be useful to carry out pretreatment in an oxygen-reduced atmosphere in order to achieve a greater range of the radiation.

[0012] The radiation source can be tubular and extend parallel to a transport direction of the containers. In a surface projection, a rectangle of length and height can result, which can be viewed as a process window in which the VUV radiation can be emitted. The containers can be transported upright in the transport direction along the radiation source. A longitudinal axis of the containers can be arranged perpendicular to the transport direction. If there are multiple radiation sources, these can be arranged flush one above the other at different heights in such a way that a process window can result which can have the length and a correspondingly at least several times the height. The resulting height with multiple radiation sources, for example three, can, due to the construction of the radiation sources, be several times greater, for example three times, than the aforementioned height of a single radiation source.Depending on the construction, a material thickness of a tube casing or the like may be added.

[0013] A pretreatment of a surface of containers by irradiating at least a part of the surface of the containers with at least a part of the VUV radiation can be carried out along a transport path in front of the process window.

[0014] The at least one radiation source can be arranged on one side of the transport path. The containers can be conveyed past by means of a transport device that can be arranged next to the at least one radiation source in such a way that a pretreatment of a container surface can be carried out as it passes the at least one radiation source by irradiating at least part of the container surface with at least part of the VUV radiation.

[0015] If there are at least two radiation sources, one can be arranged on one side of the transport route and the other on the other side of the transport route.

[0016] For example, the radiation source on one side of the transport path can be arranged at a different height than the radiation source on the other side. For example, surface segments can be pretreated at correspondingly different heights, with no overlap between the surface segments, for example.

[0017] For example, the radiation source on one side of the transport path and the radiation source on the other side of the transport path can be arranged at the same height. For example, surface segments can be pretreated at correspondingly equal heights, with no overlap of the surface segments, for example. A pretreated surface of a container can be present after it has been passed along the process window and irradiated. The dimensions of the pretreated surface and the position of the pretreated surface on the container can depend on the length and height of the process window and the relative arrangement of the process window and the container.Also, the dimension of the pretreated surface and the position of the pretreated surface on the container may depend on a transport speed of the container and / or a surface speed (when the container rotates while passing by).

[0018] After pretreating a container by irradiating at least part of the surface of the container with at least part of the VUV radiation and before printing and / or applying a primer layer, contact with at least part of the surface of the container should be avoided in order not to influence the surface properties achieved by the pretreatment.

[0019] The containers can be plastic, glass or metal containers, for example bottles, cans, flasks, ampoules, canisters, cups, drinking glasses, vases

[0020] Excimer lasers can emit coherent radiation in the ultraviolet region of the spectrum. For NeF, the wavelength can be 108 nm, for Ar2 126 nm, for Kr2 146 nm, for F2 157 nm, for Xe2 172 nm, and for ArF 193.3 nm.

[0021] VUV radiation can have a wavelength in the range of 10 nm to 200 nm.

[0022] The method may further comprise rotating the containers about their longitudinal axis while passing the containers past the at least one radiation source.

[0023] By rotating, a surface area partially or completely surrounding a container can be pretreated.

[0024] The rotation can comprise only a 360° rotation for each container as it passes the at least one radiation source. In this case, a surface area completely surrounding a container can be pretreated by irradiation.

[0025] A surface speed of at least one portion of the container surface that is to be irradiated with at least a portion of the VUV radiation or is irradiated during the process and a transport speed of the containers in a transport direction can be coordinated such that a single rotation of 360° can occur during the passage. The single rotation of 360° can occur during the passage along the entire process window of the at least one radiation source. This can be provided, for example, if the at least one radiation source is arranged on one side of the transport path.

[0026] If at least two radiation sources are provided, whereby the radiation source on one side can be arranged at a different height than the radiation source on the other side, a corresponding extensive pretreatment can be carried out at the correspondingly different heights with a single rotation of 360° while passing along the entire process window of the at least two radiation sources.

[0027] If at least two radiation sources are provided, whereby the radiation source on one side and the radiation source on the other side can be arranged at the same height, a comprehensive pretreatment at height can be carried out with a single rotation of 180° while passing along the entire process window of the at least two radiation sources.

[0028] A surface velocity of at least a portion of the container's surface that is irradiated with at least a portion of the VUV radiation may range from 10 millimeters / second to 80 millimeters / second. For example, the surface velocity may apply to a maximum diameter of the container.

[0029] For example, with a surface speed of 50 millimeters / second and a process window length of 1000 millimeters, the transport speed can be 19.36 meters / minute for a maximum container diameter of 50 millimeters, 12.77 meters / minute for a maximum diameter of 76 millimeters, and 8.00 meters / minute for a maximum diameter of 120 millimeters. Other values ​​can be specified.

[0030] The rotation can be performed by means of two belts on which the containers can be arranged, for example, upright, with the first belt moving at a first speed and the second belt moving at a second speed, whereby the first and second speeds can be different. For example, the surface speed can be obtained by the difference between the first and second speeds.

[0031] The two belts can correspond to the transport device for the containers or be included in the transport device. A transport speed for passing the containers by means of the transport device can correspond to the sum of the lower speed of the two belts and the surface speed. The two belts can be arranged next to each other in such a way that a container rests at least partially on both belts.

[0032] A first transport speed for conveying first containers past the at least one radiation source, wherein the first containers have a first maximum diameter that is smaller than a second maximum diameter of second containers, can be higher than a second transport speed of the second containers. For example, the first transport speed and the second transport speed can be such that the surface speed for the first containers and the second containers can be the same.

[0033] The method may comprise controlling and / or regulating the first speed of the first belt and the second speed of the second belt, for example depending on a maximum diameter of the container.

[0034] Additionally or alternatively, the method may comprise controlling and / or regulating the transport speed for guiding the containers past the at least one radiation source, for example as a function of a maximum diameter of the container and / or for example as a function of the first speed of the first belt and the second speed of the second belt.

[0035] Containers can be transported past the at least one radiation source in a single lane. This single-lane transport ensures that all containers can be pretreated in the same way by irradiating at least part of the container's surface with at least part of the VUV radiation. For example, partial or complete obscuration of at least part of the surface of a container by another container, for example, in multi-lane transport, can be avoided.

[0036] The method may further comprise applying a primer layer, also referred to as a primer, after irradiating at least a portion of the container's surface with at least a portion of the VUV radiation onto the irradiated at least one portion. The primer layer may be colored, white, or colorless, for example, transparent. The primer layer may be applied before printing. The primer layer can improve the adhesion of the printing ink.

[0037] It may be provided that the primer layer is applied only in the area that was previously irradiated with at least a portion of the VUV radiation. In this case, the area corresponds to the at least part of the surface of a container that was irradiated.

[0038] It may be provided to apply the primer layer to a partial area that was previously irradiated with at least a portion of the VUV radiation. In this case, the partial area is smaller than the at least part of the surface of a container that was irradiated.

[0039] It may be provided that the primer layer is applied in the area which was previously irradiated with at least part of the VUV radiation and in an adjacent area which was not irradiated with at least part of the VUV radiation.

[0040] The method may further comprise providing an oxygen-reduced atmosphere in a region of the at least one radiation source. The oxygen-reduced atmosphere may, for example, contain a maximum of 5000 ppm (ppm: parts per million) of residual oxygen. For example, the oxygen-reduced atmosphere may be nitrogen-based.

[0041] In a normal atmosphere, the range of VUV radiation can be in the range of 2 mm to 3 mm.

[0042] In an oxygen-reduced atmosphere, the range of VUV radiation can be up to 5 cm. This range allows for homogeneous pretreatment. For example, indentations on a container contour can also be safely pretreated. An oxygen-reduced atmosphere can be useful because a radiation source emitting VUV radiation is generally not a planar radiation source, but rather a tubular radiation source. For example, to pretreat a circumferential area on the surface of a container, it may be necessary to provide several radiation sources arranged parallel and one above the other.

[0043] Furthermore, a device for pretreating a surface of containers, such as plastic, glass or metal containers, prior to printing, such as digital printing, is provided, wherein the device comprises at least one radiation source, such as an excimer laser, for emitting vacuum ultraviolet radiation, VUV radiation, and a transport device for guiding containers past the at least one radiation source for irradiating at least a portion of the surface of the containers with at least a portion of the VUV radiation.

[0044] This device can be designed to carry out the method described above.

[0045] The glass containers can include surface finishes such as hot-end coating (HEC) and cold-end coating (CEC).

[0046] The radiation source can be tubular and extend parallel to a transport direction of the containers. In a surface projection, a rectangle of length and height can result, which can be viewed as a process window in which the VUV radiation can be emitted. The containers can be transported upright in the transport direction along the radiation source. A longitudinal axis of the containers can be arranged perpendicular to the transport direction. If there are multiple radiation sources, these can be arranged flush one above the other at different heights in such a way that a process window can result which can have the length and a correspondingly at least several times the height. The resulting height with multiple radiation sources, for example three, can, due to the construction of the radiation sources, be several times greater, for example three times, than the aforementioned height of a single radiation source.Depending on the construction, a material thickness of a tube casing or the like may be added.

[0047] The transport device can be linear and drivable in the transport direction, and can run parallel or substantially parallel to the radiation source. For example, the transport direction can run in the x-direction of a Cartesian coordinate system, and the longitudinal axes of the containers can run in the z-direction of the Cartesian coordinate system. A plane of the process window can run parallel to the xz-plane. Multiple radiation sources can be arranged one above the other in the z-direction, with their lengths running in the x-direction.

[0048] The at least one radiation source can be designed to emit VUV radiation with a wavelength in a range of 10 nm to 200 nm.

[0049] The transport device can comprise a rotating device for rotating the containers about their longitudinal axis as the containers are guided past the at least one radiation source. For example, the rotating device can be controlled to rotate each container only by 360° as they are guided past the at least one radiation source. For example, the rotating device can be controlled to control a surface speed of at least a portion of the surface of the containers that can be irradiated by the at least one radiation source within a range of 10 millimeters / second to 80 millimeters / second. For example, the surface speed can apply to a maximum diameter of the container.

[0050] The rotating device can comprise two belts on which the containers can be arranged, for example, upright, wherein the first belt can be driven at a first speed and the second belt at a second speed, wherein the first and second speeds can be different. For example, the surface speed can be determined by the difference between the first and second speeds.

[0051] A transport speed for passing the containers by means of the transport device can correspond to the sum of the smaller speed of the two belts and the surface speed.

[0052] By guiding the containers past the at least one radiation source by means of the transport device and the resulting rotation of the containers by means of the first belt and the second belt as well as by the relative spatial arrangement of the containers and the at least one radiation source, at least one part of the surface of the containers can be irradiated with at least part of the VUV radiation of the at least one radiation source and thus pretreated.

[0053] The device can further comprise guide rails, which can be arranged laterally of the transport device, for example, at least in a region of the at least one radiation source. The guide rails can be provided for guiding containers past the at least one radiation source in a single lane and / or as a support device for containers during rotation. For example, the guide rails can be arranged at a height such that they do not impede pretreatment of at least one part of the surface of the containers with at least part of the VUV radiation during irradiation.

[0054] The transport device can be driven such that a first transport speed for conveying first containers past the at least one radiation source, wherein the first containers have a first diameter that is smaller than a second diameter of second containers, can be higher than a second transport speed of the second containers. For example, the first transport speed and the second transport speed can be such that the surface speed for the first containers and the second containers can be the same.

[0055] The device may further comprise a control and / or regulating device which may be designed to control and / or regulate the first speed of the first belt and the second speed of the second belt, for example as a function of a maximum diameter of the container.

[0056] Additionally or alternatively, the control and / or regulating device can be designed to control and / or regulate the transport speed for guiding the containers past the at least one radiation source, for example as a function of a maximum diameter of the container and / or for example as a function of the first speed of the first belt and the second speed of the second belt.

[0057] The transport device can be designed such that containers can be guided past the at least one radiation source in a single lane.

[0058] The device may further comprise an application device for applying a primer layer after irradiating the at least one part of the surface of the containers with the VUV radiation to the irradiated at least one part before printing.

[0059] The device may further comprise a device for providing an oxygen-reduced atmosphere in a region of the at least one radiation source. For example, the oxygen-reduced atmosphere may contain a maximum of 5000 ppm of residual oxygen. For example, the oxygen-reduced atmosphere may be nitrogen-based. For example, an enclosure may be provided around the region of the at least one radiation source. Short character description

[0060] The attached figures represent aspects and / or embodiments of the invention by way of example for better understanding and illustration. It shows: Fig. 1 is an oblique view of a device for pretreating a surface of containers before printing and Fig. 2 a plan view of the device for pretreating a surface of containers before printing. Detailed character description

[0061] The Fig. Figure 1 shows an oblique view of a device 1 for pretreating the surface of containers 2 prior to printing. An exemplary container 2 is shown, embodied as a bottle. The containers 2 can be plastic, glass, or metal containers, for example, bottles, cans, flasks, ampoules, canisters, cups, drinking glasses, or vases. The glass containers can include surface finishes such as hot-end coating (HEC) and cold-end coating (CEC).

[0062] The device 1 here comprises, for example, three radiation sources 3, 4, 5, such as excimer lasers, for emitting vacuum ultraviolet radiation, VUV radiation for pretreating the surfaces of containers 2.

[0063] The radiation sources 3, 4, 5 can be tubular and extend parallel to a transport direction 6 of the containers 2. In the Fig. 1, the transport direction 6 runs in the x-direction of the specified Cartesian coordinate system. A surface projection onto a plane parallel to the xz-plane or onto the xz-plane results in a rectangle of length l and height h, which can be considered a process window 7 in which the VUV radiation can be emitted. The three radiation sources 3, 4, 5 are arranged in alignment one above the other at different heights along the z-direction of the specified Cartesian coordinate system.

[0064] The containers 2 can be transported upright and in a single lane in the transport direction 6 past the radiation sources 3, 4, 6. To transport them past the radiation sources 3, 4, 5, the containers 4 are arranged upright on a transport device 10. A longitudinal axis 9 of the containers is arranged perpendicular to the transport direction 6 and extends in the z-direction of the specified Cartesian coordinate system. The transport device 10 comprises a first belt 11 and a second belt 12, which are arranged next to one another in such a way that a container comes to rest at least partially on both belts 11, 12, and which can be driven at different speeds. The transport device 10 is linear.

[0065] The first belt 11 can be driven at a first speed and the second belt 12 at a second speed, wherein a surface speed of the containers results from the difference between the first speed and the second speed.

[0066] A transport speed for moving the containers 2 past the radiation sources 3, 4, 5 by means of the transport device 10 can correspond to the sum of the smaller speed of the two belts 1, 12 and the surface speed.

[0067] The radiation sources 3, 4, 5 are arranged on one side of the transport device 10.

[0068] By guiding the containers 2 past the radiation sources 3, 4, 5 by means of the transport device 10 and the resulting rotation of the containers 2 by means of the first belt 11 and the second belt 12 as well as by the relative spatial arrangement of the containers 2 and the radiation sources 3, 4, 5, at least a part 8 of the surface of the containers can be irradiated with at least a part of the VUV radiation of the radiation sources 3, 4, 5 and thus pretreated.

[0069] The device 1 further comprises guide rails 13, 14 arranged laterally of the transport device 10. The guide rails 13, 14 can be arranged at least in one area of ​​the radiation sources 13, 14. For example, the guide rails 13, 14 can be provided for guiding the containers 2 past the radiation sources 3, 4, 5 in a single lane and / or as a support device for the containers 2 during rotation. The guide rails 13, 14 can be arranged at a height such that they do not impede pretreatment of at least one part 8 of the surface of the containers 2 with at least a portion of the VUV radiation during irradiation.

[0070] The Fig. Figure 2 shows a top view of the device 1 for pretreating a surface of containers 2 prior to printing. The exemplary container 2 can be seen, which is arranged on the first belt 11 and the second belt 12 of the transport device.

[0071] The guide rails 13, 14 are arranged at least in the area of ​​the radiation sources 13, 14, so that the containers 2 can be guided past the radiation sources 3, 4, 5 in one lane and / or the containers 2 can be supported by the guide rails 13, 14 during rotation.

[0072] In order to provide an oxygen-reduced atmosphere in the area of ​​the radiation sources 3, 4, 5, for example, with a maximum of 5000 ppm residual oxygen, an enclosure 15 is provided around the area of ​​the radiation sources 3, 4, 5. For example, the oxygen-reduced atmosphere can be nitrogen-based.

Claims

[1] A method for pretreating a surface of containers (2), such as plastic, glass or metal containers, prior to printing, such as digital printing, the method comprising: - passing containers (2) past at least one radiation source (3, 4, 5), such as an excimer laser, which emits vacuum ultraviolet radiation, VUV radiation, - irradiating at least a part (8) of the surface of the containers (2) with at least a part of the VUV radiation. [2] The method of claim 1, wherein the VUV radiation has a wavelength in a range of 10 nm to 200 nm. [3] The method according to claim 1 or 2, further comprising rotating the containers (2) about their longitudinal axis (9) while the containers (2) are guided past the at least one radiation source (3, 4, 5). [4] The method according to claim 3, wherein the rotating for each container (2) comprises only a rotation of 360° while passing the at least one radiation source (3, 4, 5). [5] The method according to claim 3 or 4, wherein a surface speed of the at least one part (8) of the surface of the container (2) which is irradiated with at least a part of the VUV radiation is in a range of 10 millimeters / second to 80 millimeters / second, for example the surface speed being valid for a maximum diameter of the container (2). [6] The method according to any one of claims 3 to 5, wherein the rotating is carried out by means of two belts (11, 12) on which the containers (2) are arranged, for example upright, the first belt (11) moving at a first speed and the second belt (12) moving at a second speed, the first and second speeds being different, for example the surface speed being obtained by the difference between the first speed and the second speed. [7] The method according to any one of claims 1 to 6, wherein a first transport speed for guiding first containers past the at least one radiation source (3, 4, 5), the first containers having a first diameter which is smaller than a second diameter of second containers, is higher than a second transport speed of the second containers, for example the first transport speed and the second transport speed are such that the surface speed for the first containers and the second containers is the same. [8] The method according to one of claims 1 to 7, wherein the containers (2) are guided past the at least one radiation source (3, 4, 5) in a single lane. [9] The method according to any one of claims 1 to 8, further comprising applying a primer layer after irradiating the at least one part (8) of the surface of the containers (2) with at least one part of the VUV radiation to the irradiated at least one part (8). [10] The method according to any one of claims 1 to 9, further comprising providing an oxygen-reduced atmosphere in a region of the at least one radiation source (3, 4, 5), wherein, for example, the oxygen-reduced atmosphere comprises a maximum of 5000 ppm residual oxygen, wherein, for example, the oxygen-reduced atmosphere is nitrogen-based. [11] Device for pretreating a surface of containers (2), such as plastic, glass or metal containers, before printing, such as digital printing, the device comprising: - at least one radiation source (3, 4, 5), such as an excimer laser, for emitting vacuum ultraviolet radiation, VUV radiation, - Transport device (10) for guiding containers (2) past the at least one radiation source (3, 4, 5) for irradiating at least a part (8) of the surface of the containers (2) with at least a part of the VUV radiation. [12] The device according to claim 11, wherein the at least one radiation source (3, 4, 5) is designed to emit VUV radiation having a wavelength in a range of 10 nm to 200 nm. [13] The device according to claim 11 or 12, wherein the transport device (10) comprises a rotating device for rotating the containers (2) about their longitudinal axis (9) while the containers (2) are guided past the at least one radiation source (3, 4, 5), wherein, for example, the rotating device is controllable to rotate each container (2) only by 360° while it is guided past the at least one radiation source (3, 4, 5), wherein, for example, the rotating device is controllable to control a surface speed of the at least one part (8) of the surface of the containers (2) that can be irradiated by means of the at least one radiation source (3, 4, 5) in a range from 10 millimeters / second to 80 millimeters / second, wherein, for example, the surface speed applies to a maximum diameter of the container (2). [14] The device according to claim 13, wherein the rotating device comprises two belts (11, 12) on which the containers (2) can be arranged, for example upright, the first belt (11) being drivable at a first speed and the second belt (12) at a second speed, the first and second speeds being different, for example the surface speed being obtained by the difference between the first speed and the second speed. [15] The device according to one of claims 11 to 14, wherein the transport device (10) is drivable such that a first transport speed for guiding first containers past the at least one radiation source (3, 4, 5), the first containers having a first diameter which is smaller than a second diameter of second containers, is higher than a second transport speed of the second containers, for example the first transport speed and the second transport speed are such that the surface speed for the first containers and the second containers is the same. [16] The device according to one of claims 11 to 15, wherein the transport device (10) is designed such that the containers (2) are guided past the at least one radiation source (3, 4, 5) in a single lane. [17] The device according to any one of claims 11 to 16, further comprising an application device for applying a primer layer / primer after irradiating the at least one part (8) of the surface of the containers (2) with the VUV radiation onto the irradiated at least one part (8). [18] The device according to any one of claims 11 to 17, further comprising means for providing an oxygen-reduced atmosphere in a region of the at least one radiation source (3, 4, 5), for example with 5000 ppm residual oxygen, for example by adding nitrogen.

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