Method and apparatus for pretreating the surface of containers before printing

Abstract

The invention relates to a method for pretreating a surface of containers (2) before printing, comprising: emitting plasma by means of at least one plasma unit (7, 8) arranged next to a transport path for containers, with at least one plasma source (9-14) for emitting plasma and introducing at least one gaseous additive into the plasma; moving the containers along the transport path and rotating them about their longitudinal axis (5); irradiating at least a part of the container surface with at least a part of a mixture of the plasma and the additive, thereby applying a print-based adhesion coating. The invention further relates to a device (1) for pretreating a surface of containers (2) before printing with: a transport and rotation device (3) for moving the containers along a transport path and for rotating them about their longitudinal axis (5); an injection device (28-33) for introducing at least one gaseous additive into plasma from at least one plasma unit (7, 8) with at least one plasma source (9-14) for emitting plasma and for irradiating at least a part of the container surface with a mixture of the plasma and the additive, thereby applying a print-based adhesion coating.

Description

[0001] The invention relates to a method and a device for pretreating a surface of containers before printing, such as digital 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 about one-third of the total length of the pretreatment plant. Generally, only empty glass bottles can be treated.

[0005] The application of a primer layer after the above-mentioned pretreatment is required before printing. Task

[0006] The object of the invention is to provide a method and a device for pretreating a surface of containers before printing, which can enable energy and media efficient pretreatment. Solution

[0007] This object is achieved by the method and device for pretreating a container surface prior to printing according to the independent claims. Further embodiments are disclosed in the subclaims.

[0008] The invention relates to a method for pretreating a surface of containers, such as plastic, glass or metal containers, before printing, such as digital printing, the method comprising: - Emitting plasma by means of at least one plasma unit comprising at least one plasma source for emitting plasma and arranged next to a transport path for containers and introducing at least one gaseous additive into the plasma, - Moving the containers along the transport path and rotating the containers around their longitudinal axis, - Irradiating at least part of the surface of the containers with at least part of a mixture of the plasma and the at least one gaseous additive and thereby applying a pressure-based adhesive coating to at least part of the surface.

[0009] In the case of glass containers, HEC and / or CEC-coated containers can be provided. The glass containers can include surface finishes such as hot-end coating (HEC) and / or cold-end coating (CEC). The HEC and / or CEC coating can at least partially cover the surface of the glass containers. The HEC and / or CEC coating can be provided or applied before printing and before the inventive pretreatment of the surface.

[0010] For plastic and metal containers, a coating can be applied or provided before printing and before the surface pretreatment according to the invention. This coating can include roughening the surface and, for example, simultaneously applying a silane layer.

[0011] The at least one plasma unit, which comprises at least one plasma source, can offer good energy efficiency with very low output power. By using at least one plasma unit, which comprises at least one plasma source, no additional chemicals are required for cleaning, activation, and modification, for example, compared to flame treatment combined with subsequent silanization. For example, the energy consumption of using plasma can be approximately 20% that of a flame treatment with subsequent required cooling. Using the at least one plasma unit for pretreatment eliminates the need for a cooling tunnel.

[0012] The gaseous additive may be or comprise silane or pyrosil.

[0013] The introduction of the at least one gaseous additive into the plasma may comprise feeding the gaseous additive into an active plasma stream.

[0014] The at least one gaseous additive introduced into the plasma stream can react under the excitation of the plasma and can thus bind itself optimally and firmly to the surface of the container and provide the basis for good printing.

[0015] For example, the containers mentioned can be empty containers or containers filled with product. The containers can include bottles, cans, flasks, ampoules, cups, canisters, drinking glasses, or vases.

[0016] The term "pretreating a surface of containers" in this application can mean the pretreatment of at least a portion of an outer surface of the container, wherein the pretreatment comprises irradiating the surface with at least a portion of a mixture of the plasma and the at least one gaseous additive, and thereby applying a pressure-based adhesive coating to at least a portion of the surface. The irradiation can be carried out with at least a portion of a mixture of the plasma and the at least one gaseous additive, since it may happen that portions of the mixture do not reach the surface, for example, bypassing the container during an irradiation process.

[0017] The at least one gaseous additive introduced into the plasma can react under excitation by the plasma and bind to the surface of the container.

[0018] By pretreating at least a portion of the container surface, subsequent printing can be carried out more efficiently. Pretreating at least a portion of the container surface with at least a portion of a mixture can clean the corresponding surface and increase the surface energy, which can result in better wetting and adhesion during printing.

[0019] By rotating the containers, a surface area partially or completely surrounding a container can be pretreated.

[0020] The at least one plasma unit can be designed to be height-adjustable. The method can include adjusting the height of the at least one plasma unit.

[0021] For example, if a plasma unit is planned whose plasma sources can be arranged such that they can emit plasma in a treatment area of, for example, 200 mm in height, and this plasma unit is to be used to pretreat a container with a container height of 400 mm, height adjustment may be useful. For example, if printing is to begin 20 mm above the bottom edge / bottom of the container, a pretreatment area (and subsequent printing area) can be provided on the surface of the container from 20 mm to 220 mm above the bottom edge / bottom of the container. The height of the plasma unit can be adjusted by 20 mm.

[0022] For example, if a print image is to begin 100 mm above the bottom edge / bottom of the container and the corresponding surface area of ​​the container is to be pretreated accordingly, the plasma unit's height can be adjusted by 80 mm. The pretreatment area (and subsequent printing area) on the surface of the container can be positioned from 100 mm to 300 mm above the bottom edge / bottom of the container.

[0023] The method can be carried out using the device described below.

[0024] This method may eliminate the need to apply a primer layer after irradiating at least part of the surface of the containers.

[0025] The print base adhesive coating can have a thickness in a range of 7 nm to 25 nm or in a range up to 1100 nm.

[0026] The plasma may include atmospheric plasma.

[0027] The at least one plasma source can be moved alongside the transport path at a transport speed during the irradiation of at least part of the surface of the containers with the at least part of the mixture of the plasma and the at least one gaseous additive, and the containers can be moved along the transport path at the transport speed during the irradiation of at least part of the surface of the containers with the at least part of the mixture of the plasma and the at least one gaseous additive. The movement of the at least one plasma source alongside the transport path can occur in a transport direction of the containers during irradiation. The at least one plasma source can thus be moved along with the containers.

[0028] Due to the movement of at least one plasma source with the container to be irradiated, an arrangement of several plasma sources in the transport direction for irradiating a container is not necessary, for example in a plasma unit.

[0029] For example, the at least one plasma source can be moved from a starting position during the irradiation of at least a part of the surface of the container with at least a part of the mixture of the plasma and the at least one gaseous additive to an end position and can be moved back to the starting position after reaching the end position.

[0030] The location of the start and / or end positions can depend on the maximum diameter of the container. A container with a larger maximum diameter requires a longer distance to roll around its circumference than a container with a smaller maximum diameter.

[0031] For example, during the return movement from the end position to the start position, no plasma can be emitted by the at least one plasma source.

[0032] A first plasma unit and a second plasma unit can be arranged adjacent to the transport path, wherein the irradiation of at least a portion of the surface of the containers with the at least a portion of the mixture of the plasma and the at least one gaseous additive can be carried out in such a way that a first container moved along the transport path can be irradiated by the first plasma unit, and a second container following the first container can be irradiated by the second plasma unit. For example, the first plasma unit and the second plasma unit can be spaced apart from one another.

[0033] If there are many containers to be pretreated, it can be provided that containers with an odd number are pretreated by the second plasma unit and containers with an even number are pretreated by the first plasma unit.

[0034] The rotation may only involve a 360° rotation for each container during irradiation.

[0035] A surface velocity of at least a portion of the container surface that can be irradiated with the at least a portion of the mixture of plasma and at least one gaseous additive can be in a range from 100 millimeters / second to 1000 millimeters / second, for example, in a range from 400 millimeters / second to 1000 millimeters / second. For example, the surface velocity can apply to a maximum diameter of the container.

[0036] 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.

[0037] 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.

[0038] Additionally or alternatively, the method may comprise controlling and / or regulating the transport speed for guiding the containers past the at least one plasma 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.

[0039] The containers can be moved along the transport route in a single lane. This single-lane movement ensures that all containers can be pretreated by blasting at least part of their surface in the same way. 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.

[0040] The method may further include providing an oxygen-reduced atmosphere in a region of the at least one plasma unit. 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.

[0041] In a normal atmosphere, the range of the mixture of plasma and the at least one additive can be smaller than in an oxygen-reduced atmosphere. By providing an oxygen-reduced atmosphere, a homogeneous pretreatment of the containers can be achieved. For example, indentations on a container contour can also be safely pretreated.

[0042] Furthermore, there is provided a device for pretreating a surface of containers, such as plastic, glass or metal containers, before printing, such as digital printing, the device comprising: - a transport and rotating device for moving the containers along a transport path and for rotating the containers around their longitudinal axis, - an introduction device for introducing at least one gaseous additive into plasma of at least one plasma unit which is comprised by the device, wherein the at least one plasma unit is arranged next to the transport path for containers and comprises at least one plasma source for emitting plasma and for irradiating at least a part of the surface of the containers with a mixture of the plasma and the at least one gaseous additive and thereby applying a pressure-based adhesive coating to the at least a part of the surface.

[0043] The device can be designed to carry out the method described above or further below.

[0044] The transport and rotation device can be linear and drivable in the transport direction and can run parallel or substantially parallel to the at least one plasma unit, for example, parallel or substantially parallel to its longitudinal extent. 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. Multiple plasma sources of a plasma unit can be arranged one above the other in the z-direction.

[0045] The at least one plasma unit may be configured to emit atmospheric plasma.

[0046] The at least one plasma source can be designed to be movable alongside the transport path at a transport speed during the irradiation of at least part of the surface of the containers with the at least part of the mixture of the plasma and the at least one gaseous additive, and the containers can be movable along the transport path at the transport speed during the irradiation of at least part of the surface of the containers with the at least part of the mixture of the plasma and the at least one gaseous additive.

[0047] For example, the at least one plasma source can be designed to be movable from a starting position during the irradiation of at least a part of the surface of the container with the at least a part of the mixture of the plasma and the at least one gaseous additive to an end position and can be moved back to the starting position after reaching the end position.

[0048] For example, the at least one plasma source can be further configured not to emit any plasma during the return movement from the end position to the start position.

[0049] A first plasma unit and a second plasma unit can be arranged next to the transport path, wherein the device can be configured such that the irradiation of at least a portion of the surface of the container with the at least a portion of the mixture of the plasma and the at least one gaseous additive can take place such that a first container moved along the transport path can be irradiated by means of the first plasma unit, and a second container following the first container can be irradiated by means of the second plasma unit. For example, the first plasma unit and the second plasma unit can be arranged at a distance from one another.

[0050] The transport and rotation device can be controlled to rotate each container only by 360° during irradiation.

[0051] The transport and rotation device can be controlled to control a surface speed of at least one portion of the container surface that can be irradiated by the at least one plasma unit within a range of 100 millimeters / second to 1000 millimeters / second, for example, within a range of 400 millimeters / second to 1000 millimeters / second. For example, the surface speed can apply to a maximum diameter of the container.

[0052] The transport and 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 obtained by the difference between the first and second speeds.

[0053] 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.

[0054] 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 plasma unit, 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.

[0055] The transport and rotation device can be designed such that containers can be guided past the at least one plasma unit in a single lane.

[0056] The device may further comprise a device for providing an oxygen-reduced atmosphere in a region of the at least one plasma unit, for example with 5000 ppm residual oxygen, for example by adding nitrogen.

[0057] An enclosure may be provided around the at least one plasma unit, or an enclosure may be provided for each of the at least one plasma unit. The enclosure may be provided to achieve an oxygen-reduced atmosphere in the region of the plasma source(s) and / or the at least one plasma unit.

[0058] In the case of two plasma units, an enclosure can be provided around the first and second plasma units or an enclosure each around the first plasma unit and the second plasma unit.

[0059] The device may further comprise at least one suction device. The suction device may be configured to extract particles generated during irradiation, such as dust. Such particles may be generated if a portion of the at least one additive cannot be bound to the surface of the container by the plasma. 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 a vertical longitudinal section of a device for pretreating a surface of containers before printing, Fig. 2 an oblique side view of the first plasma unit and Fig. 3 an oblique plan view of the device of the Fig. 1. Detailed character description

[0061] The Fig. Figure 1 shows a vertical longitudinal section of a device 1 for pretreating the surface of containers 2 prior to printing. An exemplary container 2 is shown, designed as a bottle. The containers 2 can also be, for example, cans, flasks, ampoules, cups, canisters, drinking glasses, or vases.

[0062] The containers 2 are moved vertically by means of a Fig. 3 described in more detail, transport and turning device 3 in a transport direction 4 and rotated about its longitudinal axis 5 in a direction of rotation 6. The transport direction 4 runs in the x-direction of the Fig. 1 specified Cartesian coordinate system.

[0063] The device 1 comprises two plasma units 7, 8, each comprising, for example, three plasma sources 9, 10, 11, 12, 13, 14 arranged one above the other for emitting plasma for pretreating the surfaces of the containers 2. The three plasma sources 9, 10, 11, 12, 13, 14 are arranged in alignment one above the other at different heights along the z-direction of the specified Cartesian coordinate system. For example, the plasma sources 9, 10, 11, 12, 13, 14 can emit the plasma counter to the y-direction, whereby a spatial distribution of the plasma can occur. Furthermore, in addition to the plasma sources 9-14, introduction devices 28, 29, 30, 31, 32, 33 are provided for introducing at least one gaseous additive into the plasma of the corresponding plasma source 9-14.

[0064] Thus, at least part of the surface of the container 2 can be irradiated with at least part of a mixture of the plasma and the at least one gaseous additive, and a pressure-based adhesive coating can be applied to at least part of the surface. References below to irradiating at least part of the surface of the container 2 with at least part of a mixture of the plasma and the at least one gaseous additive also include the application of the pressure-based adhesive coating to at least part of the surface.

[0065] The first plasma unit 7 and the second plasma unit 8 are arranged next to a transport path extending in the x-direction, along which the containers 2 can be moved. The first plasma unit 7 and the second plasma unit 8 are spaced apart from each other and are spaced apart by a distance d.

[0066] The three plasma sources 9, 10, 11, 12, 13, 14 of each plasma unit 7, 8 are each arranged on a vertical support 15, 16, which is movable along horizontal rails 17, 18, 19, 20 running parallel to the x-direction in the transport direction 4 of the containers 2 and against the transport direction 4 of the containers 2. The rails 17, 18 are arranged on a frame 21 of the first plasma unit 7 and the rails 19, 20 are arranged on a frame 22 of the second plasma unit 8. Fig. 1, the plasma sources 9, 10, 11, 12, 13, 14 are each arranged such that they can be moved within the respective frame 21, 22 in the transport direction 4 of the containers 2 or against the transport direction 4 of the containers 2 by means of the carrier 15, 16.

[0067] Thus, a process window, within which the plasma sources can be moved and the mixture applied to the surface of containers 2, can be defined with a length l1, l2 and a height h1, h2. The height h1, h2 can result from the dimensions of the respective stacked plasma sources 9, 10, 11, 12, 13, 14. The length l1, l2 can result from the dimensions of the respective frame 21, 22, or, as described below, from the respective distance between the start position S1, S2 and the end position E1, E2.

[0068] The plasma sources 9, 10, 11 of the first plasma unit 7 are movable from a starting position S1 to an end position E1 during the irradiation of at least a portion of the surface of a container 2 with the at least a portion of the mixture of the plasma and the at least one gaseous additive. The end position E1 lies downstream of the starting position S1 in the transport direction 4. After reaching the end position E1, the plasma sources 9, 10, 11 of the first plasma unit 7 can be moved back from the end position E1 to the starting position S1. For example, the irradiation for pretreating the container 2 can begin at the starting position S1 and be completed or ended upon reaching the end position E1.

[0069] The plasma sources 9, 10, 11 can be moved at a transport speed alongside the transport path from the start position S1 to the end position E1 in the transport direction 4 during the irradiation of at least part of the surface of the containers 2 with the at least part of the mixture of the plasma and the at least one gaseous additive, and during the irradiation of at least part of the surface of the containers 2 with the at least part of the mixture of the plasma and the at least one gaseous additive, the containers can be moved at the transport speed along the transport path in the transport direction 4.

[0070] Accordingly, the plasma sources 12, 13, 14 of the second plasma unit 8 can be moved from a starting position S2 to an end position E2 during the irradiation of at least a portion of the surface of a container 2 with the at least a portion of the mixture of the plasma and the at least one gaseous additive. The end position E2 lies downstream of the starting position S2 in the transport direction 4. After reaching the end position E2, the plasma sources 12, 13, 14 of the second plasma unit 8 can be moved back from the end position E2 to the starting position S2. For example, the irradiation for pretreating the container 2 can begin at the starting position S2 and be completed or ended upon reaching the end position E2.

[0071] The plasma sources 12, 13, 14 can be moved at a transport speed alongside the transport path from the start position S1 to the end position E2 in the transport direction 4 during the irradiation of at least part of the surface of the containers 2 with the at least part of the mixture of the plasma and the at least one gaseous additive, and during the irradiation of at least part of the surface of the containers 2 with the at least part of the mixture of the plasma and the at least one gaseous additive, the containers can be moved at the transport speed along the transport path in the transport direction 4.

[0072] Irradiation of at least part of the surface of the containers 2 with the at least part of the mixture of the plasma and the at least one gaseous additive can be carried out in such a way that a first container 2 moved along the transport path is irradiated by means of the first plasma unit 7 and a second container 2 following the first is irradiated by means of the second plasma unit 8, etc. In the case of a large number of containers 2 which are pretreated in the device 1, this can correspond to containers 2 with an odd number being pretreated by the second and containers 2 with an even number being pretreated by the first plasma unit 7.

[0073] A first suction device 26 can be provided below the transport and rotation device 3 in a region of the first plasma unit 7, and a second suction device 27 can be provided below the transport and rotation device 3 in a region of the second plasma unit 8. Particles generated during irradiation, such as dust, can be extracted by means of the suction devices 26, 27.

[0074] The Fig. 2 shows an oblique side view of the first plasma unit 7.

[0075] The three plasma sources 9, 10, 11 are each arranged on the vertical support 15, which is aligned parallel to the z-direction and which can be moved along the horizontal rails 17, 18 running parallel to the x-direction in the transport direction 4 of the containers 2 and counter to the transport direction 4 in a second transport direction 23. The rails 17, 18 are arranged on the frame 21, so that the plasma sources 9, 10, 11 can be moved within the frame 21 in the transport direction 4 or in the second transport direction 23 by means of the support 15.

[0076] In addition, the introduction devices 28, 29, 30 arranged next to the plasma sources 9-11 for introducing the at least one gaseous additive into the plasma of the corresponding plasma source 9-11 are shown.

[0077] The Fig. 3 shows an oblique plan view of the device 1 of the Fig.1. The containers 2 are guided upright and in a single lane in the transport direction 4 past the first plasma unit 7 and the second plasma unit 8 by means of a transport and rotating device 3. For guiding past the plasma units 7, 8, the longitudinal axes 5 of the containers 2 are arranged perpendicular to the transport direction 4 and extend in the z-direction of the specified Cartesian coordinate system. The transport and rotating device 3 comprises a first belt 24 and a second belt 25, which are arranged next to one another in such a way that a container 2 comes to rest at least partially on both belts 24, 25, and which can be driven at different speeds. The transport and rotating device 3 is linear.

[0078] The first belt 24 can be driven at a first speed and the second belt 25 at a second speed, with a surface speed of the containers 2 resulting from the difference between the first speed and the second speed. In the illustration, the second speed can be higher to achieve the direction of rotation 6 of the containers 2.

[0079] A transport speed for guiding the containers 2 past the plasma units 7, 8 by means of the transport and rotating device 3 can correspond to the sum of the smaller speed of the first belt 24 and the surface speed.

[0080] By guiding the containers 2 past the plasma units 7, 8 by means of the transport and rotation device 3 and thereby rotating the containers 2 by means of the first belt 24 and the second belt 25, moving the plasma sources 9, 10, 11, 12, 13, 14 and by the relative spatial arrangement of the containers 2 and the plasma sources 9, 10, 11, 12, 13, 14, at least a part of the surface of the containers 2 can be irradiated with at least a part of the mixture of the plasma and the at least one gaseous additive and thus pretreated.

[0081] In order to provide an oxygen-reduced atmosphere in the area of ​​the plasma sources 9, 10, 11, 12, 13, 14 and / or the plasma units 7, 8, for example, with a maximum of 5000 ppm residual oxygen, an enclosure can be provided around the first and second plasma units, or an enclosure each around the first plasma unit 7 and the second plasma unit 8. 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: - emitting plasma by means of at least one plasma unit (7, 8) comprising at least one plasma source (9, 10, 11, 12, 13, 14) for emitting plasma and arranged next to a transport path for containers (2) and introducing at least one gaseous additive into the plasma, - Moving the containers (2) along the transport path and rotating the containers (2) around their longitudinal axis (5), - Irradiating at least part of the surface of the containers (2) with at least part of a mixture of the plasma and the at least one gaseous additive and thereby applying a pressure-based adhesive coating to at least part of the surface. [2] The method of claim 1, wherein the print base adhesive coating has a thickness in a range of 7 nm to 25 nm or in a range up to 1100 nm. [3] The method of claim 1 or 2, wherein the plasma comprises atmospheric plasma. [4] The method according to one of claims 1 to 3, wherein the at least one plasma source (9-14) is moved at a transport speed alongside the transport path during the irradiation of the at least part of the surface of the containers (2) with the at least part of the mixture of the plasma and the at least one gaseous additive, and wherein during the irradiation of the at least part of the surface of the containers (2) with the at least part, the containers (2) are moved at the transport speed along the transport path, wherein, for example, the at least one plasma source (9-14) is moved from a start position (S1, S2) during the irradiation of at least a part of the surface of the containers (2) with the at least a part of the mixture of the plasma and the at least one gaseous additive to an end position (E1, E2) and is moved back to the start position (S1, S2) after reaching the end position (E1, E2), wherein, for example, during the return movement from the end position (E1, E2) to the start position (S1, S2), no plasma is emitted by means of the at least one plasma source (9-14). [5] The method according to one of claims 1 to 4, wherein a first plasma unit (7) and a second plasma unit (8) are arranged next to the transport path, wherein the irradiation of at least a part of the surface of the containers (2) with the at least a part of the mixture of the plasma and the at least one gaseous additive takes place in such a way that a first container (2) moved along the transport path is irradiated by means of the first plasma unit (7) and a second container following the first is irradiated by means of the second plasma unit (8), wherein, for example, the first plasma unit (7) and the second plasma unit (8) are spaced apart from one another. [6] The method according to any one of claims 1 to 5, wherein the rotation for each container (2) comprises only a rotation of 360° during irradiation and / or wherein a surface speed of the at least part of the surface of the container (2) which is irradiated with the at least part of the mixture of the plasma and the at least one gaseous additive is in a range from 100 millimetres / second to 1000 millimetres / second, for example in a range from 400 millimetres / second to 1000 millimetres / second, wherein, for example, the surface speed applies to a maximum diameter of the container (2) and / or wherein the rotation is carried out by means of two belts (24, 25) on which the containers (2) are arranged, for example upright, the first belt (24) moving at a first speed and the second belt (25) 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 one of claims 1 to 6, wherein the movement of the containers (2) along the transport path takes place in a single track. [8] The method according to one of claims 1 to 7, further comprising providing an oxygen-reduced atmosphere in a region of the at least one plasma unit (7, 8), 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. [9] Device for pretreating a surface of containers (2), such as plastic, glass or metal containers, before printing, such as digital printing, the device (1) comprising: - a transport and rotating device (3) for moving the containers (2) along a transport path and for rotating the containers (2) about their longitudinal axis (5), - an introduction device (28, 29, 30, 31, 32, 33) for introducing at least one gaseous additive into plasma of at least one plasma unit (7, 8) which is comprised by the device (1), wherein the at least one plasma unit (7, 8) is arranged next to the transport path for containers (2) and comprises at least one plasma source (9-14) for emitting plasma and for irradiating at least part of the surface of the containers (2) with a mixture of the plasma and the at least one gaseous additive and in the process applying a pressure-based adhesive coating to at least part of the surface. [10] The device according to claim 9, wherein the at least one plasma unit (7, 8) is designed to emit atmospheric plasma. [11] The device according to claim 9 or 10, wherein the at least one plasma source (9-14) is designed to be movable at a transport speed alongside the transport path during the irradiation of at least a part of the surface of the containers (2) with the at least a part of the mixture of the plasma and the at least one gaseous additive, and wherein the containers (2) are movable at the transport speed along the transport path during the irradiation of at least a part of the surface of the containers (2) with the at least a part of the mixture of the plasma and the at least one gaseous additive, wherein, for example, the at least one plasma source (9-14) is designed to be movable from a starting position (S1, S2) during the irradiation of at least a part of the surface of the containers (2) with the at least a part of the mixture of the plasma and the at least one gaseous additive to an end position (E1, E2) and is movable back to the starting position (S1, S2) after reaching the end position (E1, E2), wherein, for example, the at least one plasma source is further designed not to emit any plasma during the return movement from the end position (E1, E2) to the start position (S1, S2). [12] The device according to one of claims 9 to 11, wherein a first plasma unit (7) and a second plasma unit (8) are arranged next to the transport path, wherein the device (1) is designed such that the irradiation of at least part of the surface of the containers (2) with the at least part of the mixture of the plasma and the at least one gaseous additive takes place such that a first container (2) moved along the transport path can be irradiated by means of the first plasma unit (7) and a second container (2) following the first container can be irradiated by means of the second plasma unit (8), wherein, for example, the first plasma unit (7) and the second plasma unit (8) are arranged at a distance from one another. [13] The device according to one of claims 9 to 12, wherein the transport and rotation device (3) is controllable to rotate each container (2) only by 360° during irradiation and / or wherein the transport and rotation device (3) is controllable to control a surface speed of the at least one part of the surface of the container (2) which can be irradiated by means of the at least one plasma unit in a range from 100 millimetres / second to 1000 millimetres / second, for example in a range from 400 millimetres / second to 1000 millimetres / second, wherein, for example, the surface speed applies to a maximum diameter of the container (2) and / or wherein the transport and rotating device (3) comprises two belts (24, 25) on which the containers (2) can be arranged, for example upright, wherein the first belt (24) can be driven at a first speed and the second belt (25) at a second speed, wherein the first and second speeds are different, wherein, for example, the surface speed is obtained by the difference between the first speed and the second speed. [14] The device according to one of claims 9 to 13, wherein the transport and rotation device (3) is designed such that the containers (2) are guided past the at least one plasma unit (7, 8) in a single track. [15] The device according to any one of claims 9 to 14, further comprising a device for providing an oxygen-reduced atmosphere in a region of the at least one plasma unit, for example with 5000 ppm residual oxygen, for example by adding nitrogen and / or further comprising a suction device (26, 27).

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