APPARATUS FOR MANUFACTURING AN ADHESIVE-FREE GAS BARRIER FILM HAVING A CERAMIC BARRIER LAYER

Abstract

The present invention relates to an apparatus for manufacturing an adhesive-free gas barrier film comprising conveying means for conveying a film web; at least one first lock system for introducing the film web into a coating chamber of the apparatus; at least one first coating means by means of which the film web can be at least partially coated by depositing a barrier material in the coating chamber; and optionally at least one second lock system for expelling the film web out of the coating chamber; and at least one second coating means by means of which the coated film web can be at least partially coated by extrusion of a plastic melt.

Claims

1-10. (canceled)

11. A method of manufacturing an adhesive-free gas barrier film comprising the steps: optionally, extruding a plastic melt to form a carrier film; conveying, in particular inline conveying, of a carrier film (30) to at least one lock system (135); introducing the carrier film (30) through the lock system (135) into a coating chamber (130); depositing a barrier layer onto the carrier film (30); optionally, expelling the film (30) through a lock system (200); and coating, in particular inline coating, of the barrier layer by applying a plastic melt.

12. A method in accordance with claim 11, characterized in that the steps extruding at least one plastic melt through at least one extrusion nozzle for manufacturing at least one carrier film (30); and conveying the obtained extruded film to the coating chamber, are carried out inline at the start of the method to obtain the carrier film (30).

13. A method in accordance with claim 11 characterized in that the conveying speed of the film amounts to at least 3 m/min, in particular between 30 m/min and 45 m/min, further in particular between 30 and 300 m/min, or up to 240 m/min, or up to 150 m/min and below, in particular to a maximum of 300 m/min, preferably to a maximum of up to 60 m/min.

14. A method in accordance with claim 11, characterized in that one or more suction chambers (115) are provided which each form a pressure stage; and in that at least one degassing chamber (120) is provided after the suction chambers (115).

15. A method in accordance with claim 11, characterized in that a film pretreatment takes place in the coating chamber (130) by irradiation with at least one ion source, with it preferably being an ion source of noble gases and/or reactive gases, in particular an ion source of argon and oxygen, and/or with the coating chamber (130) having a coating zone in which one or more ion sources (180) are arranged by means of which the film, web (30) is treated, with it preferably being an ion source of noble gases and/or reactive gases, in particular an ion source of argon and oxygen.

16. A method in accordance with claim 11, characterized in that evaporation material based on silicon and oxygen, in particular Si and/or SiOx, is evaporated in the coating chamber (130) and is deposited on the film web, and with further preferably the deposition taking place at a temperature of 1000 C. to 1500 C. or 1250 C. to 1500 C. or 1200 C.100 C., or 1300 C.100 C., in particular 1250 C.

17. A method in accordance with claim 11, wherein a cooling of the film web preferably takes place by a cooling roller in a temperature range from 70 C. to +70 C.

18-22. (canceled)

Description

[0074] Further details and advantages of the invention will now be explained in more detail with reference to an embodiment shown in the drawing.

[0075] There are shown

[0076] FIG. 1: a schematic representation of the combination method for coating carrier films with an SiOx barrier; and

[0077] FIG. 2: a schematic representation of the apparatus in accordance with the invention for manufacturing an adhesive-free gas barrier film having a ceramic barrier layer; and

[0078] FIG. 3: a schematic representation of a design of an adhesive-free composite film in accordance with the invention.

[0079] FIG. 1 shows, in a schematic representation, the combination method for coating film webs, hereinafter carrier films, with an SiOx barrier.

[0080] The starting material silicon monoxide (SiO), which is present as SiO granulate 10 in a mixture with further silicon oxide compounds, is heated in a crucible 22 surrounded by a radiation protector 24 by means of a heating wire 26 in high vacuum to temperatures of 1300-1500 C. at which it changes in a sufficient quantity into the gas phase. The vapor is deposited on the carrier film 30 led past above the evaporation furnace 20. The barrier of the SiOx layers thus generated is, however, not yet sufficient.

[0081] Sufficiently low gas permeabilities are achieved in combination with an ion source 40 (IBAD: ion-beam assisted deposition). For this purpose, the silicon suboxide, e.g. SiO.sub.1,4 condensing on the carrier film is bombarded with ionized particles. This results in a denser SiOx layer with fewer defect points.

[0082] The ion source 40 which is e.g. an argon-oxygen ion source 40 has a high-voltage supply HV and a heating not designated in more detail. The ion source 40 furthermore has an anode 44. In this respect, Ar.sup.+ and O.sub.2.sup.+ are representative for any ionized species which can be formed from the reactive gas. The total procedure takes place in a vacuum chamber 50 at a pressure of p=1*10.sup.4 to 1*10.sup.7 mbar. The vacuum is applied by the vacuum pump 52.

[0083] FIG. 2 shows, in a schematic representation, the apparatus 100 in accordance with the invention for manufacturing an adhesive-free gas barrier film having a ceramic barrier layer.

[0084] The carrier film 30 is in this respect introduced into the coating chamber 130 through the lock unit 135 and the degassing chamber 120. A suction module 150 is provided downstream of the lock module 140 and is followed by a further slit lock module 60 to reach the required process pressure. After running through a degassing chamber 120, the film moves into the coating chamber 130, where the SiOx barrier layer is vapor deposited. The SiOx vapor is generated by an evaporation furnace 170 in the coating chamber 130.

[0085] The SiOx layer is applied in association with the IBAD ion source 180. In addition, a pretreatment of the film is provided via an ion source 190 in which the surface is activated for subsequent process steps. A measurement of the film tension takes place by means of a film tension measuring device and a measurement of the layer thickness by means of a layer thickness measuring device.

[0086] A good contact to the cooling roller is indispensable to avoid a thermal overstraining of the carrier film since the process steps in the coating chamber are associated with a high heat development such that the carrier film can be destroyed. A cooling roller temperature from 50 C. to +50 C. is set in dependence on the thickness of the film 30. Finally, the coated film 30 is again expelled from the coating plant 100 via the lock modules 220, 210 and the suction chamber 230 of the lock unit 200.

[0087] The second coating means, by means of which the film web can be at least partially coated by melt extrusion, is arranged after the lock unit 200 and is shown schematically. An extrusion tool 240 in this respect applies a plastic melt onto the transported film web 30 and thus coats the just produced SiOx layer in an inline process, i.e. without process interruption and within the ongoing process.

[0088] In accordance with the principle, the manufacture of a ceramic gas barrier composite film thus essentially takes place by [0089] the extrusion of a monolayer/multilayer carrier film; [0090] the introduction of the film web into a coating plant by a vacuum lock system; [0091] the coating of the film using ion beam assisted depositionIBADof a ceramic material; [0092] the expulsion of the film by a vacuum lock system; and [0093] coating the composite film with a monolayer/multilayer top layer by melt extrusion.

[0094] It has been shown that adhesive can be dispensed with in accordance with this method. It is decisive that the ceramic coating comes into connection with the top layer in real time so that aging processes of the ceramic surface do not come into play. The non-aged surface in this respect enters into a good connection with the melt-extruded top layer. In contrast to the subject matter of EP 0 640 474, in particular the great advantage results that the application of the top layer does not have to take place in a vacuum. It is sufficient for the adhesion between the ceramic surface and the top layer that the ceramically coated carrier film and the top layer are connected inline outside the vacuum chamber. The total manufacturing process of the gas barrier film composite can thus be carried out in an inline process.

[0095] In the simplest case, the carrier film is only provided as a mechanical support for the gas barrier film. In alternative cases, the carrier layer can be of a functional design and take over essential requirements of the total composite film with respect to mechanical stability, optical quality and thermal properties which are required for the manufacture of solution bags.

[0096] It may be necessary that the carrier film is present in a thermally largely stable state, i.e. that the polymer materials may not be subject to any process of postcrystallization after extrusion. A postcrystallization of the used plastic materials after the coating with the ceramic barrier material can cause defective points in the barrier layer by material tensions. Temperature setting processes therefore take place after the extrusion of the carrier film so that possible crystallization processes can take place within the film before the deposition of the ceramic barrier material takes place.

[0097] In the simplest case, the top layer can only serve as a protective layer for the ceramic gas barrier layer. In alternative cases, the top layer can itself already be functionally designed for the manufacture of bag films and can take over mechanical, thermal and optical demands on the total composite film.

[0098] It is possible that the carrier layers and/or top layers are monolayer or multilayer, depending on the function of the total composite film.

[0099] Polyolefins, polyalphaolefins of ethylene, propylene, butylene, hexene, octene, etc., polypropylene, polyethylene, SEBS, SIS, SEPS, SEP, in alternative cases also polyesters (PET) or polyamides (PA), can be selected as materials for the carrier film and top film.

[0100] In the present method in accordance with the invention, a stable composite film is obtained directly by carrier film, barrier layer and top layer through the inline method. On the one hand, stretched carrier films can thus be dispensed with; on the other hand, the resulting composite film can be further used directly for the production of solution bags without further lamination processes to be provided.

[0101] The thickness of the carrier film and/or of the top film can amount, for example, to 10 m, but also up to 300 m for bag films. All thickness values between 10 m and up to 300 m can naturally be selected depending on the application. In particular a value between 20 and 250 m, or 10 and 50 m, preferably 30 m, is selected as the thickness value.

[0102] It is advantageously conceivable that the carrier layer amounts to 10 to 300 m, in particular 20 to 250 m, 10 to 100 m, preferably 30-100 m or 30-80 m and/or that the gas barrier layer is a ceramic layer comprising silicon suboxides (SiOx), in particular a silicon suboxide SiOx where x=1.2 to 1.9 or 1.3 to 1.8 or 1.4 to 1.7, in particular 1.7, or aluminum oxides (AlOx) and has a thickness of 10 to 500 nm, 30 to 300 nm, 15 to 150 nm, in particular 30 to 100 nm, preferably 50 nm.

[0103] A ceramic coating is in principle possible on both sides of the carrier film.

[0104] FIG. 3 shows a schematic design of a film 300 in accordance with the invention. The carrier film 340 is of monolayer design in the present example. In the course of the process, the carrier film 340 is introduced into a coating chamber via the lock system and is coated with a ceramic gas barrier material which forms into a dense layer 330. In the present case, the layer 330 is exemplary for a silicon oxide layer which was manufactured by an IBAD assisted gas deposition process. After expelling the coated carrier film from the coating chamber, the top layer is applied by melt extrusion coating. For this purpose, an extrusion melt, which is already prepressed in two layers, is applied to the carrier film; they form the tops layers 320 and 310.

[0105] In the present exemplary embodiment, the top layer is designed as two-layer, with the one layer satisfying predefined demands on the weldability of the composite film.

[0106] In this respect, the substantial demands on the total composite film with respect to mechanical stability, e.g. blow resistance, are satisfied via the layer 320 which overcoats the ceramic barrier layer 330 as the top layer.

[0107] The layer 310 is designed so that the total composite film can be welded; it can in particular also be welded in a peelable manner. The layer 310 is also called a 5sealing layer in this connection.

[0108] The carrier layer 340 has to deliver a stiff basis for the barrier layer 330. The composite film is thereby characterized with respect to a high tear propagation resistance, a high piercing resistance and a low stretching under tensile strain. It is furthermore advantageous if there is a low tendency to interlocking of the composite film, e.g. in the construction of a solution bag, over the carrier film. An interlocking tendency is here understood as the behavior of films to adhere to smooth surfaces under the effect of pressure.

[0109] Alternatively, an adhesion promoter layer not shown in FIG. 3 can also be arranged between the barrier layer 330 and the top layer 320. Adhesion promoter layers which are applied by extrusion coating are widely known.

[0110] The carrier layer 340 and the sealing layer 310 form outer layers of the composite film. In a solution bag manufactured from the film 300, the sealing layer 310 forms a side facing the bag content. The carrier layer 340 forms the outer side in such a bag.

[0111] An exemplary design of a film in accordance with the invention which is free of adhesives shows the following structure: [0112] Carrier layer (340): [0113] Layer thickness: 30 m [0114] Formulation: 100% Homo polypropylene HD 601 CF Borealis [0115] Barrier layer (330): [0116] Layer thickness: 50 nm [0117] Formulation: SiO.sub.1.70.2 [0118] Top layer (220): [0119] Layer thickness: 130 m [0120] Formulation: 70% Random copolymer of polypropylene RD 204 CF Borealis 30% SEBS Kraton G 1652 [0121] Sealing layer (210): [0122] Layer thickness: 20 m [0123] Formulation: 80% Random copolymer of polypropylene RD 204 CF Borealis 20% SEBS Kraton G 1652

[0124] The composite layer named by way of example delivers a ready-to-use gas barrier film which can e.g. be used in packaging means of foods or pharmaceuticals.

[0125] The apparatus shown in FIG. 2 can also be advantageously designed as follows:

[0126] The lock module can have a roller lock 140 in which the film is led between rollers and is sealed at the sides. It is not absolutely necessary that a pressing takes place between the rollers.

[0127] A slit lock 160 as shown schematically in FIG. 2 is furthermore provided. The film is in this respect led through a narrow gap between two metal plates. The advantage results that there are no moving parts of the lock which require a complex sealing.

[0128] Subsequently, the film runs through a degassing chamber 120 in which volatile components are separated from the film. A longer dwell time of the film in the degassing chamber is desired so that volatile substances encapsulated, dissolved or adsorbed in or at the composite film can escape.

[0129] Provision can be made for the setting of the dwell time of the films that 6 meters of film (variable depending on the plant) are led through the degassing chamber. The dwell time of the film through the degassing chamber depends on the possible film conveying speed. The conveying speed of the film is in this respect at least 3 m/min, in particular between 30 m/min and 45 m/min, further in particular between 30 and 300 m/min, or up to 240 m/min, or up to 150 m/min and below, in particular to a maximum of 300 m/min, preferably a maximum of up to 60 m/min.

[0130] A film pretreatment takes place in the coating chamber. In this respect, the film is irradiated by means of an ion source (argon, oxygen and/or further gases as already named) and the formation of plasma is brought about. A cleaning and surface activation of the carrier film to be coated hereby takes place.

[0131] Furthermore, a means for measuring the coating thickness is provided for quality assurance and online inspection. Around 50 nm is selected as a usual layer thickness for an SiOx layer. It is generally possible that a thickness from 30 to 300 nm, in particular 30 to 100 nm, or 10 to 300 nm, preferably 15 to 150 nm, preferentially 50 nm, is selected.

[0132] The starting material for the coating with silicon oxides is preferably a mixture of Si and SiO.sub.2, e.g. in a ratio of 50:50 and/or in a mixture with SiOx. The following applies preferably with respect to SiOx: SiOx where x=0 to 2; preferably where x=0.5 to 1.7 or x=0.7 to 1.3 or x=0.90.2 or x=1.00.2 or 1.10.2 or x=1.70.2. In the finished ceramic barrier layer, SiOx is preferably present in a stoichiometry of SiO.sub.1.72.

[0133] It must be noted with respect to the layer thickness that too thin a layer is admittedly flexible, but has poor barrier values, whereas too thick a layer brings about a good barrier effect, but brittle material properties, that is there is a risk of a crack formation in the barrier layer.

[0134] The Si/SiO.sub.x is evaporated and is deposited on the film. The temperature amounts to 1250 C. to 1500 C. in this respect. It is generally possible that the deposition takes place at a temperature of 1000 C. to 1500 C., 1250 C. to 1500 C., 1200 C.100 C., 1300 C.100 C., in particular 1250 C.

[0135] The spacing of nozzle to film in this respect amounts to 100 mm to 350 mm. The risk of film melting is to be considered and prevented. There is a small risk of melting due to a faster film transport since hereby the film cannot reach its melting temperature during the exposure in the coating zone.

[0136] It is conceivable that the coating roller is cooled and can in this respect be operated in a temperature range from 70 C. to +70 C.

[0137] The coating layer on the carrier film is irradiated by means of the IBAD source, with the IBAD ion source utilizing argon and oxygen. A compacting of the SiO.sub.x layer and a stoichiometric modification of the silicon oxide take place by the IBAD ion source. An advantageous stoichiometric composition of the silicon oxide with respect to thermodynamic stability, optical transparency and fluid-tightness is SiO.sub.1.2-1.9.

[0138] A preferred barrier effect for films which are used for solutions containing bicarbonate should at least have a permeability for CO.sub.2 of at most

[00001]$\mathrm{Permeability}20.Math.\frac{{\mathrm{cm}}^3\left({\mathrm{CO}}_2\right)}{\mathrm{bar}*m^2*24.Math..Math.h};\mathrm{preferably}10;$$\mathrm{further}.Math..Math.\mathrm{preferably}5;$$\mathrm{furthermore}.Math..Math.\mathrm{preferably}1,$

depending on the concentration content of the bicarbonate in solution and on the partial pressure of the CO.sub.2 then in equilibrium. Methods for the permeability determination of films are documented by standards. In particular suitable are e.g. ASTM D1434 or DIN 53380.

[0139] In the sense of the invention, the barrier films in accordance with the invention have values of gas permeability of preferably less than 20 ml(CO.sub.2)/bar/m.sup.2/24 h or 10 ml(CO.sub.2)/bar/m.sup.2/24 h, or 5 ml(CO.sub.2)/bar/m.sup.2/24 h. Corresponding permeability values which correlate in a known manner with the permeability values of oxygen apply to the oxygen barrier for barrier film in accordance with the invention.