Container with coating layer

Abstract

Container (1) with a coating layer. The present invention is in the field of containers for food and beverages. A method for applying a coating layer (2, 4) onto a preform (1, 2) for the container (1) using plasma deposition is provided. Preforms (1, 2) for the container (1) are also provided, as well as the container (1) obtained by stretching the preforms (1, 2).

Description

[Technical field]

[0001] The present invention is in the field of food and beverage containers, as well as methods for preparing these containers and preforms for use in these methods. In particular, the present invention is directed to these methods and to containers and / or preforms for such containers having a coating layer applied thereon. [Background technology]

[0002] A wide variety of containers are used in the food and beverage industry to keep the contents of the container fresh.

[0003] Such beverage containers can be made from a variety of materials. Polymeric materials such as plastics, especially thermoplastic materials, are often used for packaging food and beverages due to their light weight and strength. Suitable polymeric materials for food and beverage containers are polyesters such as polyethylene terephthalate (PET), polylactic acid (PLA), polyethylene 2,5-furandicarboxylate (PEF), and other widely available materials such as polypropylene (PP) and polyethylene (PE).

[0004] Containers made of thermoplastic polymers can be manufactured using blow molding. In this process, a container preform is produced, for example by injection molding. The container is then typically produced in a blow molding step (also called stretch blow molding) by reheating the preform using infrared radiation and stretching the reheated preform to its final shape. It is inefficient to ship empty containers. Therefore, container preforms are often manufactured at one location and shipped to a second location where the preform is blown to its final dimensions and filled.

[0005] From the perspective of reducing waste and the environmental impact, it is desirable for containers to be recyclable. Polymers such as PET, PP and PE are already recycled to a large extent, and the infrastructure for recycling such materials is in place, making it convenient to dispose of these materials responsibly. To ensure high quality of the recycled material, it is desirable to use pure materials, i.e. plastics that do not contain many other materials.

[0006] A special type of beverage container is the bag-in-container. This type of container comprises an inner layer, i.e. an inner container or bag in which the liquid is contained, and an outer layer, i.e. an outer container that provides structural integrity to the bag-in-container. To empty the inner container, an elevated gas pressure (relative to atmospheric pressure) can be applied between the outer and inner containers. This expels the fluid from the bag without gas entering the bag, thereby keeping the contents of the container fresh. Bag-in-containers are used, for example, in draft beer systems. Bag-in-containers can be produced by producing a preform comprising an inner layer, i.e. an inner preform, and an outer layer, i.e. an outer preform, and blowing the double preform together into the bag-in-container. During blowing, the inner layer of the preform is stretched to become the inner layer of the container, and the outer layer of the preform is stretched to become the outer layer of the container.

[0007] From the viewpoint of recyclability, it is desirable that the inner and outer containers of the bag-in-container are made of the same material.

[0008] For a bag-in-container system to function properly, it is important that the inner container or bag peels away from the outer container during use. This can be achieved by using different materials for the inner and outer containers that do not bond well to each other. However, using different materials for the inner and outer preforms or containers is a disadvantage when recycling the containers. Also, blow molding preforms containing different materials integrally into a bag-in-container has proven difficult, especially since different materials generally have different reheating behavior in infrared light.

[0009] In the art, a release agent is applied onto the inner preform to optimize the release. Typically, release agents such as silicone and PTFE are applied, e.g., sprayed, onto the outer surface of the inner preform. The drawback of using such release agents is that they tend to flow over the surface, resulting in an uneven distribution of the release agent on the surface of the inner preform, and parts of the surface may not be covered by the release agent at all. Furthermore, the application of the release agent may contaminate the surroundings, such as the machines used, which may interfere with subsequent process steps, such as welding.

[0010] Another approach to optimize the release is to increase the roughness of one of the preforms by including metal flakes in the preform, as described in WO 2014 / 077681. This approach can be used as an alternative to a release agent. However, in some circumstances it may still be advantageous to additionally apply a release agent to the outside of the inner preform before blow molding to further facilitate easier and controlled release of the inner container from the outer container.

[0011] EP 2 148 770 A1 describes a bag-in-container made from inner and outer preforms of the same material, in which the inner and outer layers of the container are peeled off. The application of a release agent may be advantageous in some cases. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] International Publication No. 2014 / 077681 [Patent Document 2] European Patent Application Publication No. 2148770 Summary of the Invention [Problem to be solved by the invention]

[0013] It is an object of the present invention to provide a container having at least one surface treated, which treatment is used to add various functionalities to the container. Another object of the present invention is to provide a coated container or container preform, which coating is used to add various functionalities to the container without adding a large amount of extra material to the container, thereby maintaining good recyclability of the container. [Means for solving the problem]

[0014] According to the present invention, a method is provided for applying a coating layer onto a container preform using plasma deposition.

[0015] Additionally, a method for manufacturing a container is provided.

[0016] According to another aspect of the present invention, there is provided a preform for a container comprising a coating layer applied using the methods described herein.

[0017] Also provided is a container comprising a coating layer obtained by stretching a preform as described herein.

[0018] The coating layer is applied to the container preform using low energy atmospheric pressure plasma discharge, resulting in a coating layer that is preferably cross-linked and / or covalently grafted on the surface of the preform. Surprisingly, the coating layer remains intact during blow molding, i.e. stretching the preform into a container. Using the method described herein, very thin coating layers can be achieved.

[0019] Another aspect of the present invention is the use of plasma deposition in the manufacture of a container that includes a coating layer.

[0020] More specifically, the present invention seeks to improve a container or a preform therefor in one or more of the following aspects: - peel properties (in the case of bag-in-container), i.e. an improvement in terms of peeling of the inner layer from the outer layer, meaning that the peeling of the inner layer from the outer layer before, during or after the container forming step (such as the blow stretch moulding step) is improved and as far as possible controlled; - an improvement in terms of moisture absorption, leading, for example, to an extension of the shelf life of the container or the preform therefor; - improvements in terms of heat transfer to the preform, which improves the formation of the container from the preform; an improvement in terms of colorability, which makes it possible to impart color uniformly or locally to the container; - an improvement in terms of printability, which allows printing directly on the container using known printing techniques; - Improvements in terms of gas permeability, in particular with regard to the undesirable escape of carbon dioxide, an important component of many beverages such as beer, which can lead to undesirable deterioration of the contained fluid, and also with regard to the escape of oxygen (O 2 ) from the surrounding air, for example. 2 ) regarding the unwanted inflow of -Improvements in terms of light transmission (visible or ultraviolet (UV) radiation) to avoid undesirable reactions to the contents of the container, such as lightstruck of the beer. [Brief description of the drawings]

[0021] [Figure 1] 1 is a schematic diagram of a container preform according to the present invention; [Diagram 2] 1 is a schematic diagram of a container according to the present invention; [Diagram 3] FIG. 1 shows an example of a TOF-SIMS (Time-of-Flight Secondary Ion Mass Spectrometer) analysis of a PET preform with a coating layer according to the present invention applied to the top half of the analysis area, where the detected ions are representative of the coating layer. [Figure 4] FIG. 1 shows an example of a TOF-SIMS analysis of a PET preform with a coating layer according to the present invention applied to the top half of the analysis area, where the detected ions are representative of PET. [Diagram 5] 1 shows an example of a TOF-SIMS analysis of a container produced by blow molding a preform onto which a coating layer according to the invention has been applied, the detected ions being representative of the coating layer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] According to the invention there is provided a method for applying a coating layer onto a container preform, the method comprising the steps of: a) providing a low energy cold plasma; b) exposing the coating precursor and the preform to said plasma, thereby chemically activating the precursor, the preform, or both; c) depositing a coating layer on at least a portion of the preform by reaction between the activated precursors and / or between the activated precursors and the activated preform.

[0023] A method of manufacturing a container is also provided, the method comprising the application of a coating layer as described herein, followed by a stretching step.

[0024] A low energy plasma is defined herein as a plasma whose power density is high enough to activate the precursor and / or preform to undergo a chemical reaction, but low enough to prevent destruction of the precursor, preform and / or container. The power density is between 0.2 and 8 W / dm 3 and more preferably in the range of 0.5 W / dm 3 and 7W / dm 3 and even more preferably between 0.8W / dm 3 and 6W / dm 3 and even more preferably between 1 W / dm 3 and 5W / dm 3 and even more preferably 1.5W / dm 3 and 4W / dm 3 and even more preferably between 2W / dm 3 and 3W / dm 3 For example, between 2W / dm 3 , 2.1W / dm 3 , 2.2W / dm 3 , 2.3W / dm 3 , 2.4W / dm 3 , 2.5W / dm 3 , 2.6W / dm 3 , 2.7W / dm 3 , 2.8W / dm 3 , 2.9W / dm 3 , 3W / dm 3 or any value in between, most preferably 2.4 W / dm 3 from 2.6W / dm 3 is within the range.

[0025] Cold plasma is defined herein as a plasma whose temperature is low enough not to melt or damage the precursor and / or preform exposed to the cold plasma. The temperature of the plasma may be 150°C or less, preferably 130°C or less, more preferably 100°C or less, even more preferably 70°C or less, even more preferably 60°C or less, even more preferably 55°C or less, even more preferably 50°C or less, even more preferably 45°C or less. The temperature of the plasma may be as low as room temperature, i.e., the temperature of the plasma's surroundings. Depending on the location of the coating process, room temperature may range from 10 to 40°C, preferably 15 to 30°C, for example 20 to 25°C. The temperature of the plasma generally does not fall below room temperature. When depositing temperature-sensitive coatings, it is important to stabilize the temperature of the plasma at an optimal value. The optimal temperature can be selected depending on the type and / or pressure of the precursor or precursor mixture. Thus, in an embodiment, the temperature of the plasma is selected taking into account the type of precursor, precursor mixture and / or plasma pressure.

[0026] The plasma of the present invention is preferably an atmospheric pressure plasma with a pressure near ambient pressure. Such plasma is typically generated and released at a pressure between 400 and 1600 hPa, preferably between 450 and 1400, even more preferably between 500 and 1300 hPa, even more preferably between 600 and 1250 hPa, even more preferably between 700 hPa and 1200 hPa, even more preferably between 800 hPa and 1150 hPa, even more preferably between 900 hPa and 1100 hPa, most preferably at about ambient pressure, which is typically about 1013 hPa. The pressure of the plasma can play an important role in the quality of the deposited layer. Some plasma precursors are sensitive to too low and / or too high plasma pressure compared to atmospheric pressure, while other precursors provide better coatings at lower or higher plasma pressures. However, low-energy cold plasmas can typically be applied under reduced pressure, down to a vacuum of less than 400 hPa, or under increased pressure of more than 1600 hPa, either type requiring a pressure vessel to maintain such pressure. The use of plasmas at pressures in the currently preferred range near ambient pressure can reduce the costs and difficulties associated with maintaining pressure differentials and pressure gradients.

[0027] A plasma having the above mentioned conditions is sometimes called a soft plasma. A soft plasma can provide sufficient energy to activate the precursor, the preform, or both. This allows reactions to occur, such as polymerization reactions, between the activated precursors and between the activated precursor and the activated preform. At the same time, the conditions are mild enough to prevent the precursors from being destroyed and / or losing their chemical functionality. Thus, a wide range of precursors can be used in the production of the coating layer. Even sensitive precursors such as antibodies can be activated using a soft, i.e. low-energy, cold plasma.

[0028] The plasma may be generated using a dielectric barrier discharge (DBD plasma), preferably under atmospheric pressure conditions.

[0029] A coating layer, as described herein, is defined as a layer of material of a different composition than the substrate, ie, the container preform, onto which it is deposited.

[0030] The plasma chemically activates at least one of the precursor and / or the container preform. This activation of the precursor and / or the preform can occur by opening double molecular bonds, removing radicals and / or forming ions. This enables and / or improves the reactions necessary to form the coating layer. These reactions can include: - reactions between precursors, such as polymerization reactions or crosslinking reactions, and / or Reaction between the precursor and the container preform, such as a covalent reaction. This allows reactions to occur, such as polymerization reactions, between the activated precursors, as well as between the activated precursors and the activated preform or container.

[0031] Preferably, the coating layer is covalently bonded to the surface. Preferably, the coating layer includes crosslinks, which form a covalent bond with the preform or container. Such crosslinks and covalent bonds are believed to be responsible for, or at least improve, the structural integrity of the coating. When the coating is applied to a preform that grows in size later in the process, for example by stretch blow molding, the crosslinks and covalent bonds between the coating layer and the preform prevent the coating layer from being damaged, even when the preform is stretched.

[0032] Using the methods described herein, the coating layer remains intact when the preform is stretched, for example during blow molding, including stretch blow molding. Without wishing to be bound by theory, it is believed that intermolecular crosslinks and covalent bonds between the coating layer and the preform prevent the coating layer from being damaged even when the preform is stretched.

[0033] Preferably, the preform comprises a thermoplastic material, allowing the preform to be moldable at elevated temperatures. In an embodiment, the thermoplastic material comprises one or more selected from the group consisting of polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polyethylene 2,5-furandicarboxylate (PEF), polyethylene naphthalate (PEN), and polylactic acid (PLA).

[0034] Suitable precursors can include at least one moiety selected from the group including alkanes, alkenes, alkynes, benzene derivatives, haloalkanes, fluoroalkanes, chloroalkanes, bromoalkanes, iodoalkanes, alcohols, ketones, aldehydes, acyl halides, carbonates, carboxylates, carboxylic acids, esters, methoxy, hydroperoxides, peroxides, ethers, hemiacetals, hemiketals, acetals, ketals, orthoesters, heterocycles, orthocarbonate esters, amides, amines, imines, imides, azides, azo compounds, cyanates, nitrates, nitrites, nitro compounds, nitroso compounds, oximes, pyridine derivatives, thiols, thioethers, disulfides, sulfoxides, sulfones, sulfinic acids, sulfonic acids, sulfonic acid esters, thiocyanic acids, thioketones, thials, thioesters, phosphines, phosphonic acids, phosphates, phosphodiesters, boronic acids, boronic acid esters, borinic acids, borinic acid esters, silanes, and combinations thereof. Preferably, the at least one moiety is selected from the group including alkanes, alkenes, alkynes, alcohols, silanes, and combinations thereof.

[0035] In a preferred embodiment, the precursor is selected from the group consisting of acetylene, tetraethyl orthosilicate (TEOS), cis-butene-1,4-diol, antibodies, polypeptides, precursors for protection against UV and visible light, and combinations thereof. These substances allow a significant reduction in the moisture absorption rate, but can also impart additional functionality to the preform or container.

[0036] Alternatively or additionally, the precursor may be selected from the group consisting of fluoroacrylate monomers, fluoroalkylacrylate monomers, fluoromethacrylate monomers, fluoroalkylmethacrylate monomers, fluorosilane monomers, and combinations and derivatives thereof, and cyclosiloxanes. Preferably, the coating layer is derived from a first precursor comprising a fluoroacrylate monomer, a fluoroalkylacrylate monomer, a fluoromethacrylate monomer, a fluoroalkylmethacrylate monomer, a fluorosilane monomer, or combinations or derivatives thereof, and a second precursor comprising a cyclosiloxane.

[0037] The coating layers produced from the above precursors can result in preforms with a moisture absorption coefficient lower than 0.050% by weight per week, based on the weight of the preform. As a result, the shelf life of the preform is significantly improved, for example, 4 weeks or more. This functionality can be achieved using thin coating layers, without giving the impression that the preform is defective or contaminated.

[0038] In an embodiment of the present invention, the precursor comprises one of the above list of suitable precursors. However, in other embodiments, the precursor comprises two or more of the above list of suitable precursors. In a preferred embodiment, a method is provided in which the coating layer is produced with at least two precursors, at least one of said precursors being suitable to act as a light barrier, in particular against ultraviolet (UV) and visible light. By combining at least two precursors, the coating layer can have two or more functionalities, such as reduced moisture absorption and protection against UV / visible light. Additionally or alternatively, by combining two or more precursors, improved functionality can be obtained, such as obtaining an even higher reduction in moisture absorption coefficient, which may result in a moisture absorption coefficient as low as 0.030% by weight or less per week, based on the weight of the preform.

[0039] The coating layer may act as a barrier to gases. Preferably, the coating layer is resistant to oxygen (O 2 ) and / or carbon dioxide (CO 2 ) acts as a barrier against 2 The migration of gases such as CO toward the interior of the container can cause deterioration of the container's contents. 2 If gas such as these migrates to the outside, it can lead to a deterioration in the quality of the contents, for example in the case of carbonated beverages.

[0040] In a preferred embodiment of the invention, the coating layer imparts one or more functionalities to the container preform. Since the coating layer remains intact when the preform is stretched into a container, the functionality imparted by the coating layer can be present both on the preform before stretching and on the container after the stretching step has been carried out. Such functionality can relate to one or more of the following properties: surface tension properties, which can result in, for example, hydrophobicity, reduced moisture absorption, improved release properties, improved slip properties, improved release of viscous liquids, and / or improved printability of the surface; - For example, O 2 and / or CO 2 barrier properties against gas permeation, such as oxygen, and other undesirable chemicals; -optical properties, e.g. adding color or fluorescence and / or providing a barrier against UV or visible light; -Reheating properties; - Strength of the preform, e.g. improved stress crack resistance.

[0041] The functionality of the coating layer is determined, at least in part, by the type of precursor used to create the coating layer. Table 1 summarizes which precursor types and / or specific precursors can be used to impart specific functionality as observed in the inventors' experiments.

[0042] [Table 1]

[0043] The various functionalities that can be imparted by the coating layer are described in more detail below.

[0044] a. Reduced moisture absorption One function of the coating layer may be to reduce the moisture absorption rate of the coated preform prior to expanding the preform into a full size container, for example by stretch blow molding.

[0045] When the surface of the preform is coated, the plasma deposition coating layer can result in a preform with better stretch blow molding capability compared to currently adopted methods. In the manufacturing process, repeatability is very important. Better stretch blow molding capability allows the manufacturing of plastic containers from the preform to be more repeatable.

[0046] As indicated above, the coating layer can result in a reduced rate of moisture absorption, thereby improving the shelf life of the preform. An improved shelf life is advantageous for several reasons. The production of containers from preforms, where the preforms are produced in a separate process, can be hindered for many different reasons, e.g., one or more machine breakdowns, holidays when the factory must be closed for a week or more, employee strikes, etc. Also, the preforms may need to be transported long distances with long travel times, e.g., for international shipping. In these cases, preforms close to their expiration date may already be expired by the time the containers are produced from the preforms. Thus, the overall production process may become less time- and cost-efficient. In many cases, these problems can be avoided by adopting the right management system. However, in some cases, the expiration of the preforms is unavoidable, e.g., due to unforeseen circumstances, management errors, or human error. In such cases, it would be advantageous to be able to increase the shelf life of the preforms. Increasing the shelf life of the preforms may also open up or enhance the possibility of producing preforms at a location other than the one used to produce the plastic containers. This can be particularly advantageous if, for some reason, the production of preforms is located on the other side of the world relative to the production of containers. Furthermore, increasing the shelf life of the preforms increases the possibility that the production of preforms and the production of containers can be done by different manufacturers. This can be economically beneficial and / or beneficial for technology development. Separation of manufacturers can lead to better and / or faster further development of the production process. As preforms tend to be much smaller than containers, transporting preforms is easier and cheaper than transporting containers. Therefore, it tends to be more cost-effective to manufacture preforms in a dedicated facility and transport these preforms to a second facility where the containers are manufactured and possibly filled and prepared for consumption.

[0047] If only a portion of the complete surface of the preform is treated, the moisture absorption rate may already be significantly reduced: for example, if only the outer surface is treated, the moisture absorption rate may be approximately halved, and if the preform is sealed from the environment, the moisture absorption rate may be reduced by a factor of 10 or more.

[0048] In a preferred embodiment, the preform has a moisture absorption coefficient lower than 0.070% by weight per week relative to the weight of said preform, preferably lower than 0.050% by weight per week relative to the weight of said preform, even more preferably lower than 0.040% by weight per week relative to the weight of said preform, and most preferably lower than 0.030% by weight per week relative to the weight of said preform. Currently available methods for reducing the moisture absorption rate obtain preforms with moisture absorption coefficients higher than 0.070% by weight per week relative to the weight of said preform. To enhance the shelf life of the preform, the inventors have found that the moisture absorption coefficient must be lower than 0.070% by weight per week relative to the weight of said preform. A moisture absorption coefficient lower than 0.050% by weight per week relative to the weight of said preform further enhances the shelf life of the preform. The inventors have noted that by reducing the moisture absorption coefficient to less than 0.070% by weight of the preform per week, the shelf life of the preform is increased by at least 4 weeks. Further reductions in the moisture absorption coefficient result in even higher minimum improvements in shelf life. The inventors have noted that by reducing the moisture absorption coefficient to less than 0.030% by weight of the preform per week, the shelf life is increased by more than 12 weeks.

[0049] In embodiments, the precursor comprises a fluorocarbon, a siloxane, a fatty acid and / or a hydrocarbon, or any combination thereof, preferably PFDA, HMDSO, TEOS, VEOS, V4D4, nonanoic acid, nonene, dodecane, or any combination thereof. A reduction in moisture absorption rate has been experimentally observed for such precursors.

[0050] b. Improved peelability between inner and outer layers This is particularly important in stretch blow molding infeeds, for example when producing bag-in-containers.

[0051] In embodiments, the precursor comprises a fluorocarbon, a siloxane, a polymer solution, or any combination thereof, preferably PFDA, EVOH, or any combination thereof. Improved release has been experimentally observed with such precursors.

[0052] c. Improved reheating properties This is particularly important for improving processability in stretch blow molding.

[0053] In embodiments, the precursor comprises metal nanoparticles, carbon nanoparticles, conductive polymers or any combination thereof, preferably Au, CNT, polyaniline, polythiophene or any combination thereof. Improved heat absorption has been experimentally observed for such precursors.

[0054] d.Improved sliding properties This is particularly important for improving the process in which the preforms and / or containers are conveyed, for example in a filling line.

[0055] In embodiments, the precursor comprises a fluorocarbon, a siloxane, a glycol, a hydrocarbon, a fatty acid, or any combination thereof, preferably PFDA, HMDSO, PEGMEA, DEGEA, or any combination thereof. Improved slip between containers has been experimentally observed with such precursors.

[0056] e. Adding color and / or other optical properties This is particularly important for traceability, anti-counterfeiting, or other desired functionality.

[0057] In an embodiment, the precursor comprises one or more acrylic inks, UV tracer solutions or any combination thereof, preferably STS inks, radiant UV tracers or any combination thereof. Smooth coloring of the preform or container has been experimentally observed with such precursors.

[0058] f.CO 2 Improved barrier properties In an embodiment, the precursor comprises a siloxane, a polymer solution, or any combination thereof, preferably HMDSO, VEOS, EVOH, or any combination thereof. 2 Barrier properties have been observed experimentally for such precursors.

[0059] gO 2 Improved barrier properties In an embodiment, the precursor comprises a siloxane, a polymer solution or any combination thereof, preferably HMDSO, VEOS, V4D4, EVOH or any combination thereof. 2 A barrier has been observed experimentally for such precursors.

[0060] h. Improved light barrier properties This is particularly important for visible light and / or for UV light.

[0061] In embodiments, the precursor may be a UV light absorber, a conjugated aromatic molecule, a hindered amine light stabilizer, an inorganic oxide or any combination thereof, preferably TiO 2 , Tinuvin® family, or any combination thereof. Improved light barrier has been experimentally observed for such precursors.

[0062] i. Limiting migration of undesirable chemicals from preform materials into the container contents Undesirable chemicals can migrate from the container material into the liquid within the container, for example acetaldehyde can be produced in PET materials and alter the odor and taste of the liquid contents of the container. In this regard, the present invention also aims to provide scavenging functionality.

[0063] In an embodiment, the precursor comprises a siloxane or any combination thereof, preferably HMDSO or any combination thereof. Limited migration of undesired chemicals has been experimentally observed for such precursors.

[0064] j. Improved internal anti-adhesive properties This is particularly important for easy release of viscous products such as mayonnaise, ketchup, syrup, etc., whereby the coating is applied to at least the inner surface of the preform and / or container.

[0065] In embodiments, the precursor comprises a fluorocarbon, a glycol, or any combination thereof, preferably PFDA, PEGMEA, CAS 116-143, CAS 116-15-4, DEGEA, or any combination thereof. Internal anti-blocking properties have been experimentally observed for such precursors.

[0066] k. Improved direct object printability In embodiments, the precursors include acrylate, methacrylate, hydroxyl groups, epoxy groups, or any combination thereof, preferably AA, MMA, HEMA, HEAA, GLYMA, or any combination thereof. Improved direct printability has been experimentally observed for such precursors.

[0067] l. Improved stress crack resistance In an embodiment, the precursor comprises a polymer solution, a siloxane, or any combination thereof, preferably EVOH, HMDSO, VMOS, PFDA, nonene, or any combination thereof. Improved stress crack resistance has been experimentally observed for such precursors.

[0068] The above functionality may be desired for the complete preform or container, but may also be desired or required for only a portion of the preform or container. Additionally, it may be desired that different portions of the container have different functionality, or different combinations of functionality. Thus, in embodiments of the invention, different coatings may be applied to different portions of the preform and / or container. In other embodiments, a plasma coating may be deposited on at least one portion of the preform, or over the entire surface.

[0069] The different precursors may be deposited using a layer-by-layer deposition strategy, whereby in each successive deposition step one precursor is deposited as a layer on at least one portion or on the entire surface of the preform. Another possibility involves depositing one or more layers comprising a mixture of different precursors, whereby the deposition is achieved by simultaneously introducing the different precursors into the plasma. The skilled person will note that any combination of the deposition possibilities mentioned herein may be applied to obtain a coating with at least two different precursors.

[0070] The functionality of the coating layer can depend strongly on the conditions under which it is deposited, such as temperature and pressure. To obtain good functionality, it is important to work under optimal conditions, which may vary for each precursor used, although always within the preferred ranges specified herein.

[0071] Further provided is a preform for a container comprising a coating layer applied using the method described herein. Preferably, the preform comprises a coating layer obtainable by the method described herein.

[0072] Preferably, the coating layer applied using and / or obtained by the methods described herein is crosslinked.

[0073] Additionally or alternatively, the coating layer applied using the methods described herein and / or obtained by the methods described herein is covalently grafted onto the bag-in-container preform.

[0074] Also provided is a container comprising a coating layer obtained by stretching a preform as described herein.

[0075] In an embodiment of the invention, the container may be obtained by blow molding of a preform.

[0076] The use of plasma deposition to apply coating layers, for example to reduce moisture absorption, provides a means of controlling the coating deposition process down to nanoscale precision. Thickness control is important because depositing layers that are too thick can result in a coating that is ostensibly visible. A coating that is visible can give the impression of a defective or contaminated preform, which is undesirable. In the context of this specification, it is noted that the coating can produce visible effects, such as a color or a smooth appearance. However, it is an advantage of the present invention that such effects do not appear to be the result of the coating.

[0077] The coating layer deposited on the preform may have a thickness between 5 and 600 nm, preferably between 5 and 500 nm, more preferably between 10 and 500 nm, even more preferably between 10 and 300 nm, even more preferably between 10 and 200 nm, even more preferably between 10 and 80 nm, such as 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm or any value therebetween, most preferably about 20 nm. The thickness of the plasma coating can be well controlled by controlling the exposure time of the preform or container to the plasma and / or precursor.

[0078] In an embodiment of the invention, the container can be obtained by integrally stretching the preform, the stretch ratio being between 2 and 20. Preferably, the stretch ratio in terms of volume is between 5 and 20, more preferably between 10 and 15, even more preferably between 12 and 15, such as 12, 13, 14, 15 or any value therebetween, most preferably about 13.5. Preferably, said preform is increased in length with a stretch ratio between 2 and 20, preferably between 3 and 15, more preferably between 4 and 12, even more preferably between 5 and 10, and / or said preform is increased in diameter with a stretch ratio between 2 and 20, preferably between 3 and 15, more preferably between 4 and 12, even more preferably between 5 and 10. During the step of increasing the size of the preform, the length, diameter and / or volume are increased according to the ranges mentioned above. The thickness of the coating layer decreases with increasing stretch ratio. It is believed that the thickness of the coating on the preform decreases inversely proportional to the increase in surface. The theoretical inverse proportionality of the thickness reduction to the 2 / 3 power of the volumetric stretch ratio does not necessarily hold because the shape of the preform may change during the size increase. Preferably, the thermoplastic preform is stretched in length as well as in diameter during the integral stretching.

[0079] After stretching, the coating layer on the container may have a thickness of 100 nm or less. Preferably, the coating layer has a thickness of 80 nm or less, more preferably 50 nm or less, for example 20 nm or less. The thickness of the coating layer after stretching may be as low as 5 nm, but is preferably greater than 5 nm. In an embodiment, the thickness of the coating layer on the container is 30 nm or less, more preferably 25 nm or less, even more preferably 20 nm or less, even more preferably 15 nm or less, even more preferably 10 nm or less, for example 10 nm, 9 nm, 8 nm, 7 nm, 6 nm, 5 nm, 4 nm, 3 nm, 2 nm, 1 nm or any value therebetween, most preferably about 6 nm. Preferably, the coating on the container is at least 2 nm thick.

[0080] Due to the low thickness of the coating layer, only a small portion (e.g. less than 1% by weight) of the total amount of material in the preforms and containers according to the invention is coating material, so that the coated preforms and containers can be successfully recycled without adversely affecting the quality of the recycled material.

[0081] In an embodiment, the preform may be a bag-in-container preform including an inner preform and an outer preform having opposing surfaces, at least one of which is coated with a coating layer applied using the method described herein. In that case, the coating layer may be applied to one or more of the surfaces of the inner preform, the outer preform, the inner preform, and the outer preform. Preferably, the coating layer is applied to at least the outer preform, the inner preform, or both. In principle, the coating layer can be applied to a portion of these surfaces or to the entirety of these surfaces. Preferably, the coating layer is applied to the entirety of the surface. In that way, the surface properties of the inner and / or outer surface of the preform or container to which the coating layer is applied are determined primarily by the properties of the coating layer.

[0082] Preferably, the coating layer is intact. An intact coating layer is defined as a coating layer that covers the entire surface to which it is applied. Thus, the coating layer has no areas where the material of the surface to which it is applied is exposed. In this way, the surface properties, such as the release properties, of the preform or container to which the coating layer is applied are determined by the properties of the coating layer. Preferably, the coating layer remains intact during stretching of the preform, resulting in an intact coating layer on the container.

[0083] To confirm the presence of an intact coating layer having a thickness according to the invention, surface techniques such as time-of-flight secondary ion mass spectrometry (TOF-SIMS) can be applied, as shown in Figures 3-5.

[0084] According to the invention, the coating layer is applied to at least a portion of the surface. In some applications, certain portions of the surface may be intentionally left uncoated. For example, to improve the peel properties, the neck portion of the preform used for preparing the bag-in-container does not need to be coated since it is not usually deformed during blow molding.

[0085] Alternative methods of characterization of the coating layer may include optical measurements. Since a wide variety of precursors can be used to form the coating layer, optically active components such as pigments or dyes can also be incorporated into the coating layer. These optically active components can be detected using optical detection methods. For example, if a fluorescent material is incorporated into the coating layer, the presence of an intact coating layer may be demonstrated using fluorescence measurements. In a preferred embodiment, a colorant such as a pigment or dye is added to the plasma, preferably as a gas or liquid, or as a powder dissolved in a liquid or colloidal mixture in the form of an aerosol. The coloring facilitates quality confirmation by visual inspection, but can also be used for other visual effects. For example, if a fluorescent material is incorporated into the coating layer, the presence of an intact coating layer can be demonstrated using fluorescence measurements. Furthermore, if it is intended to later apply printing directly to the container, providing the colorant already in the plasma can provide a more uniform background color in a simpler and faster way than performing the coloring process on top of the coating.

[0086] Preferably, the coating layer is a conformal coating layer, which conforms closely to the surface even when the surface contains a large curvature, for example near an opening, near a neck, or near the bottom of a preform or container.

[0087] In the case of bag-in-container preforms, the inner and outer preforms of the preforms may be made of the same and / or different materials. A coating layer applied to the outside of the inner preform and / or the inside of the outer preform can prevent contact between the material of the inner preform and the material of the outer preform. In that case, the same material of the inner and outer preforms do not come into contact. Instead, if a coating layer is present on at least one of the opposing surfaces, the release properties are determined by the interaction between the coating layer and the other opposing surface or between the two coating layers. In this way, the coating layer can optimize the release of the inner and outer layers, for example, before, during and / or after blow molding.

[0088] If the preform is composed of multiple preforms, for example a bag-in-container preform, such preform may be formed by joining two or more superimposed preforms, i.e. an inner preform and an outer preform, using methods known in the art. Non-limiting examples of such methods include spin welding of the inner preform and the outer preform, for example as described in EP 2 885 241 A1. There may be areas such as neck areas where contact between the inner preform and the outer preform is intentionally made to achieve preform joining. It is noted that bag-in-container preforms, in which the same materials of the inner and outer preforms are not in contact with each other as described herein, do not preclude intentional contact between the inner and outer preforms in certain areas, such as the neck area of ​​the bag-in-container preform, to achieve the required structural integrity.

[0089] Figure 1 is a schematic diagram of a cross section of a container preform according to the invention. With reference to Figure 1, a container preform (1) is provided, which comprises a coating layer (2). In Figure 1, the coating layer is present on the outside of the preform. Alternatively or additionally, the coating layer may be present on the inside of the preform.

[0090] Figure 2 is a schematic cross-sectional view of a container obtained by blow molding of a preform (1), showing a container (3) comprising a coating layer (4). In Figure 2, the coating layer is present on the outside of the container. Alternatively or additionally, the coating layer may be present on the inside of the container.

[0091] In embodiments, the coating layers described herein may have a low surface energy. Coatings with low surface energy may provide different functionalities, including but not limited to reduced moisture absorption and improved delamination of the inner and outer layers. Coating layers with low surface energy may also be referred to as hydrophobic coating layers. Preforms are often manufactured at one location and blown into containers at a different location, such as the same location where the blown containers are filled. This allows for a significant reduction in shipping compared to shipping blown containers. However, preforms have a limited shelf life and the blowability of the preforms may decrease after a certain period of time. Preforms with low surface energy coating layers have been found to have increased shelf life. This also applies to containers with hydrophobic coatings. Low surface energy and / or hydrophobicity can be expressed in terms of water contact angle.

[0092] In a preferred embodiment, the coating layer is hydrophobic. The preferred contact angle may be 90° or more, preferably 100° or more, more preferably 120° or more, for example 150° or more. When the water contact angle is 150° or more, the coating layer may be referred to as superhydrophobic. In a preferred embodiment, the coating layer is superhydrophobic.

[0093] Surprisingly, the hydrophobic coating applied in accordance with the present invention need not result in a color change in the product that is commonly observed in other prior art methods of improving shelf life, such as the use of scavengers or applying a water-resistant layer to the interior and / or exterior surfaces of the preform.

[0094] During use of a bag-in-container, elevated gas pressure (relative to atmospheric pressure) is typically applied between the outer and inner containers, expelling fluid from the bag without gas entering the bag, thereby keeping the contents of the container fresh. For proper functioning during use, it is important that the inner container or bag peels away from the outer container.

[0095] In an embodiment relating to a bag-in-container, the inner container is peeled away from the outer container after the bag-in-container preform is blown together in a controlled manner.

[0096] Another aspect of the present invention is the use of plasma deposition for the manufacture of a container comprising a coating layer.

[0097] The present invention is further illustrated by the following non-limiting examples which further illustrate the invention but are not intended, nor should they be construed, to limit the scope of the invention.

[0098] Example 1: Coating Integrity To test the coating uniformity and coating integrity, two single-wall preforms were provided after blowing the preforms into full-sized containers. The preforms were made by injection molding a combination of PET particles and silver colorant, resulting in a dark grayish preform. This color helped to make the effect of the coating more visible.

[0099] Preform 1 was not treated and was used as a reference. Preform 2 was treated with a plasma coating according to the invention. During the coating process of the preforms, a green pigment was added to the plasma via an aerosol.

[0100] The preform was then expanded through the preform opening by blow stretching to a full size bottle with a ratio of about 11.

[0101] The reference bottle ("Bottle 1") obtained from Preform 1 had small defects near the top of the so-called "Lamello" area around the opening (a hardened ring or series of rings extending around the perimeter of the container, resulting from increased crystallization in the preform) and near the bottom around the injection point of the preform. Both defects are typical of the blow-draw process. Bottle 1 was a light grayish color with small intensity variations near the two defects.

[0102] The bottle obtained from preform 2 (hereafter referred to as Bottle 2) exhibited a smooth, uniform light green color throughout the bottle (except for the same type of intensity fluctuations near the defect). The uniform light green color of Bottle 2 indicates that the coating remained intact even after expanding the preform by a volume ratio of as much as 11. The pigment is well dispersed throughout the bottle, and the coating adheres very well to all surfaces of the preform and bottle.

[0103] Example 2: Surface Energy The coating on the preform and the resulting container can serve multiple purposes. For example, it can act as a moisture barrier that can avoid degradation of the preform during storage. It may also act as a moisture barrier for the container. Other effects include providing color (by adding pigments, for example by adding pigments to the plasma as shown in the previous examples).

[0104] Also, a release coating can be applied in accordance with the present invention to ensure easy release of the inner container from the outer container of a double-walled container (eg, bag-in-container).

[0105] If the surface energy is reduced, the peeling is significantly reduced. In particular, the peeling at a given pressure level is better controlled. However, plasma treatment without coating tends to increase the surface energy. The inventors have found that, nevertheless, the surface energy is reduced when at least one precursor is administered into the plasma in the form of an aerosol, either as a gas or liquid.

[0106] To test for surface energy reduction, two preforms were prepared, both containing PET with a silver colorant to provide an easy background color when using the pen test described below.

[0107] Preform 1 was left untreated, while preform 2 was provided with a coating according to the present invention.

[0108] The surface energy of the preform is tested using a set of test pens with different types of ink, each type of ink having a well-calibrated surface energy. If the surface energy of the substrate is equal to or greater than the surface energy of the ink, the ink will expand on the surface, resulting in a smooth and uniform coloration. If the surface energy of the substrate is lower than the surface energy of the ink, the ink will coalesce into non-uniform droplets.

[0109] Both preforms were subjected to three test pens, with surface energies of 34mN / m, 38mN / m and 44mN / m respectively. Untreated preform 1 had a surface energy between 38 and 44mN / m, consistent with the general assumption that PET has a surface energy between 40 and 50mN / m, and was found to be difficult to paint and required more force to peel.

[0110] The treated preforms had a surface energy of less than 34 mN / m, resulting in improved peelability when used, for example, in double walled containers (eg, bag-in-containers).

[0111] This example shows that the surface energy can be reduced using plasma with precursors. However, the inventors have noted that certain precursors can also increase the surface energy of the coated surface. Such high surface energy may be desirable to obtain other functionalities, particularly improved direct printability (resulting in accurate, high quality printed images). (Additional Note) (Appendix 1) 1. A method for applying a coating layer onto a container preform, comprising the steps of: a) providing a low energy cold plasma; b) exposing the coating precursor and the preform to said plasma, thereby chemically activating the precursor, the preform, or both; c) depositing a coating layer on at least a portion of the preform by reaction between the activated precursors and / or between the activated precursors and the activated preform; A method comprising: (Appendix 2) 2. The method of claim 1, wherein the coating layer is covalently grafted onto the preform. (Appendix 3) 3. The method of claim 1 or 2, wherein the coating layer is crosslinked such that the layer remains intact when the preform is stretched. (Appendix 4) 4. The method of any one of claims 1 to 3, wherein the preform comprises a thermoplastic material. (Appendix 5) The thermoplastic material is selected from the group consisting of PET, PLA, PEF, PEN, PP and PE. 5. The method of claim 4, comprising one or more selected. (Appendix 6) 6. The method of any one of claims 1 to 5, wherein the coating layer provides the preform with hydrophobic properties. (Appendix 7) 7. The method of claim 6, wherein the hydrophobicity is imparted by a coating layer derived from a first precursor comprising a fluoroacrylate monomer, a fluoroalkyl acrylate monomer, a fluoromethacrylate monomer, a fluoroalkyl methacrylate monomer, a fluorosilane monomer, or a combination or derivative thereof, and a second precursor comprising a cyclosiloxane. (Appendix 8) 8. The method of any one of claims 1 to 7, wherein the plasma is atmospheric air. (Appendix 9) 9. The method of any one of claims 1 to 8, wherein the coating layer is applied to the entire surface of the preform. (Appendix 10) 10. A method for producing a container comprising the method of any one of claims 1 to 9 and a subsequent stretching step. (Appendix 11) A preform for a container comprising a coating layer applied using the method according to any one of claims 1 to 9. (Appendix 12) 12. A container comprising a coating layer obtained by stretching the preform according to claim 11. (Appendix 13) 13. A container according to claim 12, obtained by blow molding the preform. (Appendix 14) 14. The container according to claim 12 or 13, wherein the stretch ratio of the blow molded container is 5 to 20. (Appendix 15) 15. The container of any one of claims 12 to 14, wherein the coating layer is intact. (Appendix 16) Use of plasma deposition using a low-energy cold plasma for the manufacture of a container including a coating layer. [Explanation of symbols]

[0112] 1 Preform 2 Coating Layer 3 containers 4 Coating Layer

Claims

1. 1. A method for applying a coating layer onto a container preform, comprising the steps of: a) providing a low energy cold plasma, which is an atmospheric plasma generated and discharged at a pressure between 400 and 1600 hPa and is generated using a dielectric barrier discharge; b) exposing the coating precursor and the preform to said cold plasma, thereby chemically activating the precursor, the preform, or both; c) depositing a coating layer on at least a portion of the preform by reaction between the activated precursors and / or between the activated precursors and the activated preform. Steps: A method comprising:

2. The method of claim 1 , wherein the coating layer is covalently grafted onto the preform.

3. 3. The method of claim 1 or 2, wherein the coating layer is crosslinked so that the coating layer remains intact when the preform is stretched.

4. The method of claim 1 , wherein the preform comprises a thermoplastic material.

5. 5. The method of claim 4, wherein the thermoplastic material comprises one or more selected from the group consisting of PET, PLA, PEF, PEN, PP and PE.

6. The method of claim 1 , wherein the coating layer provides the preform with hydrophobic properties.

7. 7. The method of claim 6, wherein the hydrophobicity is imparted by a coating layer derived from a first precursor comprising a fluoroacrylate monomer, a fluoroalkylacrylate monomer, a fluoromethacrylate monomer, a fluoroalkylmethacrylate monomer, a fluorosilane monomer, or a combination or derivative thereof, and a second precursor comprising a cyclosiloxane.

8. The method according to claim 1 , wherein the coating layer is applied to the entire surface of the preform.

9. A method for producing a container comprising the method according to any one of claims 1 to 8 and a subsequent stretching step.

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