WO2022135724A1

WO2022135724A1 - Method of treating a coated flexible substrate for packaging applications

Info

Publication number: WO2022135724A1
Application number: PCT/EP2020/087823
Authority: WO
Inventors: Zheng TIAN; Rajan Verghese; Rainer Demuth; Shasha LIU
Original assignee: Applied Materials, Inc
Priority date: 2020-12-23
Filing date: 2020-12-23
Publication date: 2022-06-30
Also published as: CN116981722A; JP2024505344A

Abstract

A method of treating a coated flexible substrate is described. The method of treating a coated flexible substrate includes providing the coated flexible substrate comprising a flexible substrate including a first surface and a second surface opposite the first surface and at least one barrier layer on the first surface of the flexible substrate and providing a beam of charged particles to the at least one barrier layer and the flexible substrate of the coated flexible substrate simultaneously in a substantially oxygen-free atmosphere.

Description

METHOD OF TREATING A COATED FLEXIBLE SUBSTRATE FOR PACKAGING APPLICATIONS

TECHNICAL FIELD

[0001] Embodiments of the present disclosure relate to a method of treating a coated flexible substrate for packaging applications.

BACKGROUND

[0002] Coated flexible substrates made of polymeric flexible substrates and barrier layers deposited thereon are known in packaging industries for packing food, chemical goods, pharmaceuticals or agricultural products and for protecting these packed goods from detrimental moisture and/or oxygen.

[0003] Most commonly used coated flexible substrates comprise a polymeric flexible substrate onto which at least one barrier layer is deposited. Currently, in most cases, metals (e.g. aluminum and tinplate), polymers (e.g. EVOH or PVDC), polymers coated with thin metallic or oxide layers are used as barrier materials. In order to produce such coated flexible substrates, one or more barrier layers may be deposited at the surface of the polymeric flexible substrate by evaporation processes. In some cases, an uppermost layer made of a polymer is additionally provided on the barrier layer(s).

[0004] Although such commonly used barrier layers provide good protection against moisture and/or oxygen, deterioration of their barrier properties after a certain period of time has been observed. Further, in the case where the barrier layers are damaged, for instance, during transportation of the goods protected by the coated flexible substrates, the barrier properties of the coated flexible substrates are also diminished. Furthermore, protecting very sensitive goods, such as electronic devices, from moisture and/or oxygen demands coated flexible substrates with extremely low oxygen transmittance rates. [0005] Accordingly, there is a continuous need for methods for generally improving the barrier properties of coated flexible substrates for packaging applications.

SUMMARY

[0006] In light of the above, a method of treating a coated flexible substrate for packaging applications is provided. The present disclosure aims to provide a method for improving the oxygen barrier properties of coated flexible substrates for packaging applications. Further, the present disclosure aims to increase the oxygen barrier properties of coated flexible substrates without requiring additional barrier materials or complex production systems. Accordingly, the method is conducted with low manufacturing costs and high production efficiency. Furthermore, the present disclosure aims to provide coated flexible substrates with an additional protection for goods, which can act in the case of damage to the barrier layers disposed on the flexible substrate or when oxygen has reached the flexible substrate after diffusing through the barrier layers disposed on the flexible substrate. In addition, the present disclosure aims to create new functionalities acting as oxygen scavengers in the already present flexible substrate of the coated flexible substrate, such that additional oxygen barrier properties are provided.

[0007] Further aspects, benefits, and features of the present disclosure are apparent from the claims, the description, and the accompanying drawings.

[0008] According to an aspect of the present disclosure, a method of treating a coated flexible substrate for packaging applications is provided. The method of treating a coated flexible substrate includes providing the coated flexible substrate comprising a flexible substrate including a first surface and a second surface opposite the first surface and at least one barrier layer on the first surface of the flexible substrate. The method further includes providing a beam of charged particles to the at least one barrier layer and the flexible substrate of the coated flexible substrate simultaneously in a substantially oxygen-free atmosphere. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments. The accompanying drawings relate to embodiments and are described in the following:

Fig. 1 shows a flowchart illustrating a method of treating a coated flexible substrate for packaging applications according to embodiments described herein;

Fig. 2 shows a schematic representation for illustrating a method of treating a coated flexible substrate for packaging applications including microscopic views of the coated flexible substrate according to embodiments described herein;

Figs. 3 A to 3C show schematic cross-sectional side views of coated flexible substrates for packaging applications according to embodiments described herein;

Figs. 4 shows a schematic view of an apparatus for treating a coated flexible substrate for packaging applications according to embodiments described herein.

DETAILED DESCRIPTION OF EMBODIMENTS

[0010] Reference will now be made in detail to the various embodiments, one or more examples of which are illustrated in the figures. Within the following description of the drawings, the same reference numbers refer to same components. Generally, only the differences with respect to individual embodiments are described. Each example is provided by way of explanation and is not meant as a limitation of the disclosure. Further, features illustrated or described as part of one embodiment can be used on or in conjunction with other embodiments to yield yet a further embodiment. It is intended that the description includes such modifications and variations.

[0011] Coated flexible substrates, for instance, made of polymeric flexible substrates and barrier layers deposited thereon for preventing moisture and/or oxygen from diffusing or passing the coated flexible substrates, are known in packaging industries for packing food, chemical goods, and pharmaceuticals as well as technical or other agricultural products. However, deterioration of the barrier properties of the coated flexible substrates after a certain period of time has been observed. For instance, in the case where the barrier layers deposited on the flexible substrates are damaged during transportation of the goods protected by the coated flexible substrates, the barrier properties of the coated flexible substrates are diminished. Further, after a certain period of time, oxygen diffuses through the barrier layers disposed on the flexible substrate, which also decreases the protection of the goods from oxygen, for instance. Furthermore, the protection of certain goods from oxygen, e.g., electronic devices, demands coated flexible substrates with extremely low oxygen transmittance rates.

[0012] Yet, the present disclosure aims to provide a method for improving the oxygen barrier properties of coated flexible substrates for packaging applications. Examples of packaging applications may include modified atmosphere packaging. In particular, providing a beam of charged particles to a coated flexible substrate comprising at least one barrier layer and a flexible substrate in a substantially oxygen-free atmosphere helps to create new functionalities acting as oxygen scavengers in the already present flexible substrate of the coated flexible substrate. The newly created functionalities provide additional oxygen barrier properties to the coated flexible substrate.

[0013] Further, providing a beam of charged particles to a coated flexible substrate comprising at least one barrier layer and a flexible substrate in a substantially oxygen-free atmosphere results in the scission of the polymeric chains of part of the flexible substrate which imparts additional oxygen barrier properties to the coated flexible substrate. In other words, free radicals are produced in the flexible substrate of the coated flexible substrate as a result of providing a beam of charged particles to the coated flexible substrate and the corresponding scission of the polymeric chains of part of the flexible substrate. The free radicals act as oxygen scavengers once oxygen has reached the flexible substrate after diffusing through the at least one barrier layer, for instance once the at least one barrier layer is damaged during transportation of the goods to be protected.

[0014] The present disclosure aims to improve the oxygen barrier properties of coated flexible substrates without requiring additional barrier materials or complex production systems. Accordingly, the method of the present disclosure is conducted with low manufacturing costs and high production efficiency. [0015] With exemplary reference to Fig. 1, a method 100 of treating a coated flexible substrate for packaging applications according to the present disclosure is described. The method 100, beginning at start 110, may include providing the coated flexible substrate comprising a flexible substrate including a first surface and a second surface opposite the first surface and at least one barrier layer on the first surface of the flexible substrate (stage 120). Further, the method 100 of treating a coated flexible substrate for packaging applications may include providing a beam of charged particles to the at least one barrier layer and the flexible substrate of the coated flexible substrate simultaneously in a substantially oxygen-free atmosphere (stage 130). Method 100 may conclude at end 140.

[0016] Before various further embodiments of the present disclosure are described in more detail, some aspects with respect to some terms used herein are explained.

[0017] In the present disclosure, a “flexible substrate” may be characterized in that the substrate is bendable. For example, the flexible substrate may be a foil or a web. In particular, it is to be understood that embodiments as described herein can be utilized for processing any kind of coated flexible substrates for packaging applications. The flexible substrate as described herein may include a substrate material selected from the group consisting of polyethylene, polypropylene, polyisobutylene, polyvinylidene chloride, polytetrafluoroethylene, polyamide, polyethylene terephthalate, polystyrene, polyethylene vinyl alcohol, polyethylene vinyl acetate, polyethylene methacrylate, and combinations thereof. Particularly, the flexible substrate is a polymeric flexible substrate. The flexible substrate may have a substrate thickness T_s of T_s < 250 pm, particularly 5 pm < T_s < 150 pm, more particularly 5 pm < T_s < 100 pm, e.g. T_s = 50 pm ± 1 pm. It is understood that selecting a flexible substrate with a thickness T_s as specified herein can be beneficial to provide scissions of the polymeric chains of part of the flexible substrate and, therefore, free radicals to act as oxygen scavengers without deteriorating the mechanical properties of the flexible substrate.

[0018] In the present disclosure, the term “charged particles” can be understood as particles with an electric charge. For instance, charged particles can be ions or electrons. According to an embodiment, the charged particles are electrons.

[0019] In the present disclosure, the term “barrier layer” can be understood as a coating, a layer or a film, which provides oxygen barrier properties, particularly oxygen and moisture barrier properties, to the coated flexible substrate. The barrier layer and/or the at least one barrier layer may have oxygen barrier properties, particularly oxygen and moisture barrier properties.

[0020] As an example, when reference is made to the term “on”, e.g., at least one barrier layer on the first surface of the flexible substrate, it is understood that, starting from the flexible substrate, the at least one barrier layer is positioned on the flexible layer. In other words, the term “on” is used to define an order of the at least one barrier layer, the barrier layers thereof and/or the flexible substrate, wherein the starting point is the flexible substrate. This is irrespective of whether the coated flexible substrate is depicted upside down or not.

[0021] Fig. 2 shows a schematic representation for illustrating the method 100 of treating the coated flexible substrate for packaging applications including microscopic views of the coated flexible substrate according to embodiments described herein. In particular, the coated flexible substrate may include a flexible substrate 210 including a first surface and a second surface opposite the first surface and at least one barrier layer 220 on the first surface of the flexible substrate 210. In some embodiments, the at least one barrier layer 220 may be directly on the first surface of the flexible substrate 210.

[0022] According to some embodiments, which can be combined with other embodiments, providing the coated flexible substrate may further include providing at least one barrier layer 220 on the first surface of the flexible substrate 210, particularly directly on the first surface of the flexible substrate 210.

[0023] In some embodiments, providing the coated flexible substrate may also include providing a coating composition on the at least one barrier layer 220, e.g., in a substantially oxygen-free atmosphere, particularly directly on the at least one barrier layer 220. In such a case, the coated flexible substrate may further include a coating composition. Further, providing a beam of charged particles 240 to the at least one barrier layer 220 and the flexible substrate 210 of the coated flexible substrate simultaneously in a substantially oxygen-free atmosphere may also include providing a beam of charged particles 240 to the coating composition simultaneously in a substantially oxygen-free atmosphere. In some embodiments, the coating composition may include acrylate monomers, methacrylate monomers, acrylate oligomers, methacrylate oligomers, and combinations thereof. [0024] The coating composition may form an uppermost layer on the at least one barrier layer 220, e.g., after curing or polymerizing by providing the beam of charged particles. The uppermost layer may provide mechanical protection to the at least one barrier layer, e.g, against mechanical damage. The uppermost layer may also have oxygen barrier properties, particularly moisture and oxygen barrier properties. The coating composition can be provided on the at least one barrier layer 220 by using a coating method, and particularly by a solution coating method, particularly selected from the group consisting of gravure coating, flow coating, curtain coating, dip coating, spray coating, printing coating, and combinations thereof. In some embodiments, the uppermost layer may have a thickness T_c of 0.1 pm < T_c < 1.5 pm, particularly 0.1 pm < T_c < 0.7 pm, more particularly 0.1 pm < T_c < 0.5 pm.

[0025] As exemplarily illustrated in Fig. 2, according to embodiments which can be combined with other embodiments described herein, a beam of charged particles 240 can be provided from a charged particle source 230 positioned on the at least one barrier layer 220 or on the coating composition. Such a position of the charged particle source 230 can be beneficial since curing or polymerization of the coating composition on the at least one barrier layer 220 can be additionally conducted during the treatment of the coated flexible substrate for packaging applications according to the present disclosure. Accordingly, in embodiments with a coating composition on the at least one barrier layer 220, providing a beam of charged particles 240 to the coating composition, to the at least one barrier layer 220, and to the flexible substrate 210 of the coated flexible substrate simultaneously in a substantially oxygen-free atmosphere may further include curing or polymerizing the coating composition on the at least one barrier layer 220, e.g., by employing the beam of charged particles 240. Curing or polymerization of the coating composition on the at least one barrier layer 220 and treating the coated flexible substrate for packaging applications according to the present disclosure may be conducted simultaneously.

[0026] Further, the position of the charged particle source 230 allows curing or polymerization of the coating composition on the at least one barrier layer 220 without passing the beam of charged particles 240 across a substrate thickness Ts of the flexible substrate 210 and, therefore, curing or polymerization of the barrier layer of at least one barrier layer 220 is achieved with reduced charged particle energy E. Furthermore, such a position of the charged particle source 230 can be beneficial, since the free radicals produced in the flexible substrate can act as oxygen scavengers only once oxygen has reached the flexible substrate after diffusing through the at least one barrier layer or once the at least one barrier layer is damaged, for instance, during transportation of the goods protected by the coated flexible substrates. However, it is to be understood that the position of the charged particle source 230 is not limited to a position on the at least one barrier layer 220 or on the coating composition, and that any suitable position that allows curing or polymerization of the coating composition on the at least one barrier layer 220 could be used.

[0027] It is to be understood that embodiments of the present disclosure are not limited to the charged particle source 230 for providing the beam of charged particles 240. The embodiments described herein are for explanation of the concept of the method of treating the coated flexible substrate for packaging applications. Accordingly, it is to be understood that more than one charged particle source for providing the beam of charged particles 240 can be implemented.

[0028] In some embodiments, the beam of charged particles 240 may have a cone-like shape. For instance, the cone-like shape can be substantially symmetric with respect to a main direction of the respective beam. In Fig. 2, the main direction 240M is indicated.

[0029] According to some embodiments, which can be combined with other embodiments, a charged particle energy E of the charged particles of the beam of charged particles 240 can be 5 keV < E < 250 keV, particularly 30 keV < E < 220 keV, and more particularly 50 keV < E < 220 keV. In some embodiments, a charged particle dose of the beam of charged particles 240 can be 1000 to 1 x 10⁵ Gray, particularly 3000 to 1 x 10⁴ Gray, more particularly 3000 to 8000 Gray. It is to be understood that the values of the charged particle energy E of the charged particles of the beam of charged particles 240 and the values of the charged particle dose of the beam of charged particles can be adjusted according to the material(s) and/or thickness(es) of the at least one barrier layer and/or the flexible substrate.

[0030] As exemplarily indicated by the double-sided arrow in Fig. 2, the flexible substrate can be moved in a transport direction T, e.g., while treating the coated flexible substrate for packaging applications according to the method of the present disclosure. Accordingly, the method of treating the coated flexible substrate for packaging applications may further include moving the coated flexible substrate in a transport direction T. For instance, moving the coated flexible substrate may include moving the coated flexible substrate at a speed v_s of 1 m/s < v_s< 15 m/s, particularly 2 m/s < v_s < 10 m/s, more particularly 3 m/s < v_s < 7 m/s, e.g. v_s = 4.5 m/s ± 0.5 m/s or v_s = 6.0 m/s ± 0.5 m/s. According to another example, the speed v_s at which the coated flexible substrate is moved can be 12 m/s < v_s< 15 m/s.

[0031] As exemplarily shown in Fig. 2, the beam of charged particles 240 provided to the at least one barrier layer 220 and the flexible substrate 210 of the coated flexible substrate simultaneously in a substantially oxygen-free atmosphere may penetrate the at least one barrier layer 220 and the flexible substrate 210 of the coated flexible substrate simultaneously. In embodiments with a coating composition on the at least one barrier layer 220, the beam of charged particles 240 provided to the coating composition, to the at least one barrier layer 220, and to the flexible substrate 210 of the coated flexible substrate simultaneously in a substantially oxygen-free atmosphere may penetrate the coating composition, the at least one barrier layer 220, and the flexible substrate 210 of the coated flexible substrate simultaneously.

[0032] In some embodiments, providing a beam of charged particles 240 to the at least one barrier layer 220 and the flexible substrate 210 of the coated flexible substrate simultaneously in a substantially oxygen-free atmosphere may further include adjusting at least one of the charged particle energy E of the charged particles of the beam of charged particles 240 and the charged particle dose of the beam of charged particles 240. In embodiments with a coating composition on the at least one barrier layer 220, providing a beam of charged particles 240 to the coating composition, to the at least one barrier layer 220, and to the flexible substrate 210 of the coated flexible substrate simultaneously in a substantially oxygen-free atmosphere may further include adjusting at least one of the charged particle energy E of the charged particles of the beam of charged particles 240 and the charged particle dose of the beam of charged particles 240

[0033] Accordingly, a variation of the charged particle energy E of the charged particles of the beam of charged particles 240 adjusts an average penetration depth 21 Op of the beam of charged particles 240 in the flexible substrate 210. Therefore, the scission of the polymeric chains of the flexible substrate 210 and the corresponding free radicals can be created at different penetration depths in the flexible substrate 210. Further, a variation of the charged particle dose of the beam of charged particles 240 adjusts the number of scissions of the polymeric chains of the flexible substrate 210 and the corresponding free radicals at an average penetration depth 21 Op in the flexible substrate 210. [0034] The term “penetration depth” in the present disclosure refers to the distance the beam of charged particles 240 penetrates the flexible substrate 210 starting from the first surface of the flexible substrate 210, e.g., on which the at least one barrier layer is positioned or deposited, for instance, along a thickness direction. In some embodiments, an average penetration depth 21 Op of the charged particles of the beam of charged particles 240 in the flexible substrate 210 from the first surface is equivalent to at least 10% of a substrate thickness T_s of the flexible substrate, particularly at least 40% of a substrate thickness T_s of the flexible substrate, and more particularly at least 70% of a substrate thickness T_s of the flexible substrate.

[0035] Figs. 3 A to 3C show schematic cross-sectional side views of coated flexible substrates for packaging applications according to embodiments described herein. In Figs. 3A to 3C, the coated flexible substrate according to the present disclosure includes a flexible substrate 310 including a first surface and a second surface opposite the first surface and at least one barrier layer 320 on the first surface of the flexible substrate 310, particularly directly on the first surface of the flexible substrate 310.

[0036] In some embodiments, as exemplarily shown in Fig. 3A, the coated flexible substrate according to the present disclosure may include a flexible substrate 310 including a first surface and a second surface opposite the first surface and a barrier layer 320 on the first surface of the flexible substrate 310, particularly directly on the first surface of the flexible substrate 310.

[0037] In some embodiments, as exemplarily shown in Fig. 3B, the coated flexible substrate according to the present disclosure may include a flexible substrate 310 including a first surface and a second surface opposite the first surface, a first barrier layer 320a on the first surface of the flexible substrate 310, particularly directly on the first surface of the flexible substrate 310, and a second barrier layer 320b on the first barrier layer 320a, particularly directly on the first barrier layer 320a. Accordingly, the at least one barrier layer 320 may include a first barrier layer 320a and a second barrier layer 320b. As an example, the first barrier layer 320a may include aluminum or aluminum oxide. Further, the second barrier layer 320b may include an organic material such as acrylate monomers, methacrylate monomers, acrylate oligomers, methacrylate oligomers, polyacrylates, polymethacrylates, melamine resin, and combinations thereof. [0038] In some embodiments, as exemplarily shown in Fig. 3C, the coated flexible substrate according to the present disclosure may include a flexible substrate 310 including a first surface and a second surface opposite the first surface, a first barrier layer 320a on the first surface of the flexible substrate 310, particularly directly on the first surface of the flexible substrate 310, a second barrier layer 320b on the first barrier layer 320a, particularly directly on the first barrier layer 320a, and a third barrier layer 320c on the second barrier layer 320b, particularly directly on the second barrier layer 320b. Accordingly, the at least one barrier layer 320 may include a first barrier layer 320c, a second barrier layer 320b, and a third barrier layer 320c. As an example, the first barrier layer 320a may include aluminum or aluminum oxide. Further, the second barrier layer 320b may include silicon dioxide. Furthermore, the third barrier layer 320c may include an organic material such as acrylate monomers, methacrylate monomers, acrylate oligomers, methacrylate oligomers, polyacrylates, polymethacrylates, melamine resin, and combinations thereof. As a further example, the first barrier layer 320a may include polyvinyl alcohol and/or polyethylene vinyl alcohol. Further, the second barrier layer 320b may include aluminum, aluminum oxide and/or silicon dioxide. Furthermore, the third barrier layer 320c may include an organic material such as acrylate monomers, methacrylate monomers, acrylate oligomers, methacrylate oligomers, polyacrylates, polymethacrylates, melamine resin, and combinations thereof.

[0039] The at least one barrier layer 320 or at least one of the barrier layers of the at least one barrier layer 320, e.g., the first barrier layer 320a, the second barrier layer 320b or the third barrier layer 320c, may include a material selected from the group consisting of aluminum, aluminum oxide, aluminum nitride, silicon, silicon dioxide, organic materials, and combinations thereof. Examples of organic materials are polyvinyl alcohol, polyethylene vinyl alcohol, polyvinylidene dichloride, acrylate monomers, methacrylate monomers, acrylate oligomers, methacrylate oligomers, polyacrylates, polymethacrylates, melamine resin, and combinations thereof. However, it is to be understood that the material of the at least barrier layer 320 or at least one of the barrier layers of the at least one barrier layer 320 is not limited to aluminum, aluminum oxide, aluminum nitride, silicon, silicon dioxide, organic materials, and combinations thereof, and that any suitable materials having oxygen barrier properties, particularly moisture and oxygen barrier properties, could be used as a material of the at least one barrier layer 320 or of at least one of the barrier layers of the at least one barrier layer 320. [0040] In some embodiments, the at least one barrier layer 320 or at least one of the barrier layers of the at least one barrier layer 320, e.g., the first barrier layer 320a, the second barrier layer 320b or the third barrier layer 320c, can be an oxygen barrier. In some embodiments, the at least one barrier layer 320 or at least one of the barrier layers of the at least one barrier layer 320, e.g., the first barrier layer 320a, the second barrier layer 320b or the third barrier layer 320c, can be a moisture and an oxygen barrier.

[0041] In some embodiments, a water vapor transmission rate (WVTR; in units of g per cm² per day) and/or an oxygen transmission rate (OTR) of the coated flexible substrate treated according to the method of the present disclosure can be less than 10, particularly less than 1, and more particularly about 0.5. Oxygen and water vapor transmission rates can be determined in compliance with ASTM D3985-17 and ASTM F1249-20, using a Mocon Oxtran 2/22 and Systech Illinois 8001 for oxygen permeation and a Mocon Permatran-W 3/33 and Systech Ilinois 7001 for water vapor permeation.

[0042] According to some embodiments, the at least one barrier layer 320 or at least one of the barrier layers of the at least one barrier layer 320, e.g., the first barrier layer 320a, the second barrier layer 320b or the third barrier layer 320c, can be manufactured by chemical vapor deposition or physical vapor deposition, for example sputtering or evaporation. Examples of physical vapor deposition can be electron-beam physical vapor deposition and sputter deposition. In some embodiments, providing the coated flexible substrate may include depositing at least one barrier layer on the flexible substrate, particularly directly on the flexible substrate.

[0043] Alternatively, at least one barrier layer 320 or at least one of the barrier layers of the at least one barrier layer 320, e.g., the first barrier layer 320a, the second barrier layer 320b or the third barrier layer 320c, can be provided on the flexible substrate 310 by using a coating method, and particularly by a solution coating method, particularly selected from the group consisting of gravure coating, flow coating, curtain coating, dip coating, spray coating, and combinations thereof, e.g., when the precursors of the at least one of the barrier layers of the at least one barrier layer 320, e.g., the first barrier layer 320a, the second barrier layer 320b or the third barrier layer 320c, are in a liquid state and include organic materials such as polyvinyl alcohol, polyethylene vinyl alcohol, acrylate monomers, methacrylate monomers, acrylate oligomers, methacrylate oligomers, polyacrylates, polymethacrylates, melamine resin, and combinations thereof. In some embodiments, the at least one barrier layer 320 may have a thickness T_b of 0.05 pm < T_b < 5 pm, particularly 0.1 pm < T_b < 2 pm, more particularly 0.1 pm < T_b < 1 pm.

[0044] According to an aspect of the present disclosure, a coated flexible substrate for packaging applications is provided. In some embodiments, the coated flexible substrate can be a substrate that has been treated by the method of the present disclosure. The coated flexible substrate may include a flexible substrate including a first surface and a second surface opposite the first surface and at least one barrier layer on the first surface of the flexible substrate. In some embodiments, the at least one barrier layer may be directly on the first surface of the flexible substrate. The properties of the flexible substrate and of the at least one barrier layer of the treated coated flexible substrate for packaging applications such as substrate thickness T_s, substrate material, thickness Tb, and material of the at least one barrier layer are as described in the present disclosure. In some embodiments, a water vapor transmission rate (WVTR; in units of g per cm² per day) and/or an oxygen transmission rate (OTR) of the coated flexible substrate, e.g., after having been treated according to the method of the present disclosure, can be less than 10, particularly less than 1, and more particularly about 0.5. Oxygen and water vapor transmission rates can be determined as described in the present disclosure.

[0045] With exemplary reference to Fig. 4, an apparatus 400 for treating a coated flexible substrate 440 for packaging applications according to the present disclosure is described. According to embodiments which can be combined with other embodiments described herein, the apparatus 400 includes a processing drum 410 for guiding the coated flexible substrate 440. Additionally, the apparatus 400 includes a printing arrangement 420 for printing, e.g., a coating composition on at least one barrier layer of the coated flexible substrate 440. As an example, the at least one barrier layer may include aluminum or aluminum oxide. Further, the apparatus 400 includes a charged particle source 430 for treating the coated flexible substrate 440.

[0046] With exemplary reference to Fig. 4, the printing arrangement 420 may include a supply device 421 for supplying a coating composition. For instance, the supply device 421 can be a monomer reservoir. Further, the printing arrangement 420 may include a first roller 422 (e.g. an anilox roller) and a second roller 424 (e.g. a transfer roller). In particular, the first roller 422 may be arranged parallel to the processing drum 410 and the second roller 424. Between the transfer roller and the processing drum 410, the coated flexible substrate 440 may be transported during processing, e.g. coating or printing of the coating composition on the at least one barrier layer of the coated flexible substrate 440. Accordingly, it is to be understood that the coating composition can be applied to the surface of the first roller 422, e.g. the surface of an anilox roller, from the reservoir while the surface of the first roller 422 passes through the reservoir. Further, as exemplarily shown in Fig. 4, typically the printing arrangement 420 includes a doctor blade assembly 423 having at least one elongated doctor blade extending in a parallel direction to the rotation axis of the first roller 422.

[0047] This written description uses examples to disclose the disclosure, including the best mode, and also to enable any person skilled in the art to practice the described subject-matter, including making and using any apparatus and performing any incorporated methods. While various specific embodiments have been disclosed in the foregoing, mutually non-exclusive features of the embodiments described above may be combined with each other. The patentable scope is defined by the claims, and other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

[0048] While the foregoing is directed to some embodiments, other and further embodiments may be devised without departing from the basic scope, and the scope is determined by the claims that follow.

Claims

1. A method of treating a coated flexible substrate for packaging applications, comprising: providing the coated flexible substrate comprising:

- a flexible substrate including a first surface and a second surface opposite the first surface, and

- at least one barrier layer on the first surface of the flexible substrate; providing a beam of charged particles to the at least one barrier layer and the flexible substrate of the coated flexible substrate simultaneously in a substantially oxygen-free atmosphere.

2. The method of treating a coated flexible substrate according to claim 1, wherein the beam of charged particles is provided from a charged particle source positioned on the at least one barrier layer.

3. The method of treating a coated flexible substrate according to claims 1 or 2, wherein providing a beam of charged particles to the at least one barrier layer and the flexible substrate of the coated flexible substrate simultaneously in a substantially oxygen-free atmosphere further includes adjusting at least one of a charged particle energy E of the charged particles of the beam of charged particles and a charged particle dose of the beam of charged particles.

4. The method of treating a coated flexible substrate according to any of the previous claims, wherein a charged particle energy E of the charged particles of the beam of charged particles is 5 keV < E < 250 keV, particularly 30 keV < E < 220 keV, and more particularly 50 keV < E < 220 keV.

5. The method of treating a coated flexible substrate according to any of the previous claims, wherein a charged particle dose of the beam of charged particles is 1000 to 1 x 10⁵ Gray, particularly 3000 to 1 x 10⁴ Gray, more particularly 3000 to 8000 Gray.

6. The method of treating a coated flexible substrate according to any of the previous claims, wherein an average penetration depth of the charged particles of the beam of charged particles in the flexible substrate from the first surface is equivalent to at least 10% of a substrate thickness T_s of the flexible substrate, particularly at least 40% of a substrate thickness T_s of the flexible substrate, and more particularly at least 70% of a substrate thickness T_s of the flexible substrate.

7. The method of treating a coated flexible substrate according to any of the previous claims, wherein the flexible substrate has a substrate thickness T_s of < 250 pm, particularly 5 pm < T_s < 150 pm, more particularly 5 pm < T_s < 100 pm.

8. The method of treating a coated flexible substrate according to any of the previous claims, wherein the flexible substrate comprises a substrate material selected from the group consisting of polyethylene, polypropylene, polyisobutylene, polyvinylidene chloride, polytetrafluoroethylene, polyamide, polyethylene terephthalate, polystyrene, polyethylene vinyl alcohol, polyethylene vinyl acetate, polyethylene methacrylate, and combinations thereof.

9. The method of treating a coated flexible substrate according to any of the previous claims, wherein the charged particles are electrons.

10. The method of treating a coated flexible substrate according to any of the previous claims, wherein the at least one barrier layer is an oxygen barrier.

11. The method of treating a coated flexible substrate according to any of the previous claims, wherein the at least one barrier layer has a thickness T_b of 0.05 pm < T_b < 5 pm, particularly 0.1 pm < T_b < 2 pm, more particularly 0.1 pm < T_b < 1 pm.

12. The method of treating a coated flexible substrate according to any of the previous claims, wherein the at least one barrier layer comprises a material selected from the group consisting of aluminum, aluminum oxide, aluminum nitride, silicon, silicon dioxide, organic materials, and combinations thereof.

13. The method of treating a coated flexible substrate according to any of the previous claims, wherein providing the coated flexible substrate further includes providing a coating composition on the at least one barrier layer and providing a beam of charged particles further includes providing a beam of charged particles to the coating composition simultaneously in a substantially oxygen-free atmosphere. - 17 - The method of treating a coated flexible substrate according to claim 13, wherein the coating composition comprises acrylate monomers, methacrylate monomers, acrylate oligomers, methacrylate oligomers, and combinations thereof. The method of treating a coated flexible substrate according to any of claims 13 and 14, wherein the coating composition forms an uppermost layer on the at least one barrier layer after polymerizing by providing the beam of charged particles.