DE102009003218A1 - Halogen-free barrier film useful in packaging industries and display technologies, comprises a weather-stable carrier layer, and an inorganic oxide layer, where the carrier layer is applied on an inorganic transparent barrier layer - Google Patents

Abstract

The halogen-free barrier film comprises a weather-stable carrier layer (1), and an inorganic oxide layer, where the carrier layer is an coextrudate of methacrylate and polyolefin or polyester and is applied on an inorganic transparent barrier layer (2) on the polyolefin side or polyester side. The barrier film has a partial discharge voltage of 1000 V, and has a transparency of more than 80% in the area of more than 300 nm. An independent claim is included for a method for producing a barrier film.

Description

Field of the invention

The The invention relates to a barrier film made of plastics that is weather-resistant and is transparent and has a high barrier to water vapor and oxygen. The barrier film consists of a carrier layer (Coextrudate of (meth) acrylate and polyolefin or polyester) and an inorganic oxide layer.

State of the art

A weather-resistant, transparent and impact-resistant films based on poly (meth) acrylate-based marketed by the applicant under the name PLEXIGLAS ^®. The patent DE 38 42 796 A1 describes the preparation of a clear, impact-resistant (meth) acrylate-based molding composition, films and moldings produced therefrom, and a process for the preparation of the molding composition. These films have the advantage that they do not discolor under heat and moisture. Furthermore, they avoid the so-called white fracture when impact or bending stress. These films are transparent and remain so even when exposed to heat and moisture, weathering and impact or bending stress.

The Processing of the molding composition to said transparent, impact-resistant Foils are ideally made by extrusion of the melt through a Slot nozzle and smoothing on a roller mill. such Films are characterized by lasting clarity, insensitivity against heat and cold, weather resistance, low yellowing and embrittlement and low whiteness when kinking or folding out and are therefore suitable, for example as a window in tarpaulins, car covers or sails. Such slides have a thickness of less than 1 mm, for example 0.02 to 0.5 mm. One important application is the formation of thin surface layers from Z. B. 0.02 to 0.5 mm thickness on stiff, dimensionally stable Basic bodies, such as sheets, cardboard, chipboard, plastic sheets and the same. Stand for the preparation of such coatings different procedures available. So can the slide extruded into a molding compound, smoothed and applied to the substrate be laminated on. By the technique of extrusion coating For example, an extruded strand may be applied to the surface of the substrate and smoothed by a roller. If as a substrate even a thermoplastic material is used, there is the possibility the coextrusion of both masses to form a surface layer from the clear molding compound of the invention.

In the published patent application DE 10 2005 019 669 A1 The applicant describes a film membrane with, inter alia, excellent weatherability and high mechanical strength and a process for their preparation. The properties are achieved by a composite of a base film of thermoplastic material and a cover layer of poly (meth) acrylate. The adhesion is achieved by copolymers with polar character. The base film is a fabric of, for example, high density polyethylene (HDPE), polypropylene (PP) or polyesters.

In the EP 911 148 adhesives are presented, the u. a are provided with "reactive monomers" and are suitable for the adhesion of LCP films on polyethylene substrates. The multiple films are heated above the melting point of the highest melting single component so as to achieve intimate fusion of the individual films together.

The EP 271 068 reports on blends of polyvinyl fluoride and PMMA-GMA copolymers laminated to modified polystyrene sheets at elevated temperatures.

In the DE 10 010 533 there is proposed a multilayer film consisting of two layers, the first layer being acrylic resin and the second layer each being a copolymer of either an acrylic resin and an olefin-based copolymer obtained by copolymerizing an olefin and at least one monomer selected from e.g. As unsaturated carboxylic acids, carboxylic anhydrides or glycidyl groups containing monomers. This film is said to have excellent melt adhesion to polyolefin-based resin substrates. Thus, in this process, two polymer layers are laminated together and then with the "reactive monomers" -containing side of the polyolefin resin to be laminated z. B. applied by means of an adhesive molding process.

In the DE 43 370 62 For example, metal sheets having triple layers of thermoplastic resins are laminated so that a temperature of at least 30 ° C is set above the glass transition temperature of the inner resin layer during the extrusion coating process.

The Japanese application H9-193189 describes as well as the DE 10 010533 a multi-layer composite of a first layer which consists of a thermoplastic PMMA polymer, a second layer consisting of a reactive-modified polyolefin and a third layer, which is composed of a colored olefin polymer.

To the desired above mentioned To obtain advantageous properties of materials such as high and permanent adhesion, etc., the known state of the art offers only special individual solutions that can not be generalized or appear disadvantageous from the apparatus or logistical effort, in particular the processing of multi-layer materials as a protective layer.

PMMA films However, they offer only insufficient barrier properties Water vapor and oxygen, but for medical applications, Applications in the packaging industry, but especially in electrical Applications that are used outdoors, is necessary.

To improve the barrier properties, transparent, inorganic layers are applied to polymer films. In particular, silicon oxide and aluminum oxide layers have prevailed. This inorganic oxide layer (SiO _x or AlO _x ) is used in the vacuum coating process (chemical, JP-A-10025357 . JP-A-07074378 ; thermal or electron beam evaporation, sputtering, EP 1 018 166 B1 ) applied. In EP 1 0181 66 B1 It is shown that the ratio of silicon to oxygen of the SiOx layer can influence the UV absorption of the SiOx layer. This is important to protect underlying layers from UV radiation. The disadvantage, however, is that as the ratio of silicon to oxygen changes, the barrier property also changes. Thus transparency and barrier can not be varied independently of each other.

The inorganic oxide layer is sometimes applied mainly to polyesters and polyolefins because these materials withstand the temperature stress during the evaporation process. In addition, the inorganic oxide layer adheres well to polyesters and polyolefins, the latter undergoing corona treatment prior to coating. However, since these materials are not weather-stable, they are often laminated with halogenated films, such as in WO 94/29106 is described. The problem with laminates is that the individual layers separate from one another when exposed to high levels of heat and moisture. Halogenated films are problematic for environmental reasons.

How out U. Moosheimer, Galvanotechnik 90 No. 9, 1999, p. 2526-2531 As is known, the coating of PMMA with an inorganic oxide layer does not improve the barrier to water vapor and oxygen since PMMA is amorphous. However, unlike polyesters and polyolefins, PMMA is weather-stable.

Therefore would the combination of PMMA and a polyester or Polyolefin, on which the inorganic oxide layer is applied can solve this problem.

The Partial discharge voltage depends on the foil material and of the layer thickness. To a partial discharge voltage of 1,000 V also become laminates of several layers of film produced.

How out Amberg-Schwab et al., Journal of Sol-Gel Sciene and Technology 1/2 (1998), p. 141-146 As is known, the imperfections which always occur in inorganic oxide layers can be closed by organic-inorganic sol-gel hybrid systems. So they improve the barrier effect when applied to the inorganic SiOx layer, since they close the defects. This effect is especially strong on polypropylene. The disadvantage of these sol-gel systems, however, is the limited weathering resistance and the long curing process by hydrolysis.

In the published patent application DE10260067A1 Applicant describes deformable scratch-resistant coatings. These have the advantage that they not only for solid moldings, but also for flexible plastic moldings, such. As films can be used. Furthermore, they are UV-stable and dirt-repellent. However, they do not adhere to inorganic layers, such as. For example, silica or alumina layers.

task

Of the Invention is based on the object, a barrier film available which is weather-stable and highly transparent (> 85% in the wavelength range> 380 nm), with high Barrier properties to water vapor and oxygen be guaranteed. PMMA fulfills the property the weathering stability, the inorganic oxide layer fulfills the properties of the barrier.

The First, the present invention has the object of making PMMA weather-resistant Layer to combine with an inorganic oxide layer, which is the Barrier function improved because the direct coating of PMMA in the prior art does not result in an improved barrier leads. Second, the function of protection against UV radiation should not be taken over by the inorganic oxide layer more so that they are optimized exclusively according to optical criteria but from the PMMA layer. Third, with this Material combination a partial discharge voltage of greater than 1,000 V can be achieved.

solution

The object is achieved by a barrier film which has a transparent carrier layer. This carrier layer is a coextrudate of PMMA or impact-resistant PMMA and a polyolefin or a polyester. This polyolefin or polyester layer may be coated with an inorganic oxide layer, thereby improving the water vapor and oxygen barrier. The PMMA layer is weather-resistant and contains a UV absorber, which protects the polyolefin or polyester layer from UV radiation and thus extends their durability. The carrier layer also has a sufficient layer thickness to ensure the partial discharge voltage of 1,000 volts. This is ideally done by the polyolefin or polyester layer, as this is less expensive than the PMMA layer. In order to achieve the smoothest and flawless surface of the film, the coextrusion of the two materials on a sleeve-touch system is recommended as an option. In such a system, the melt is pressed after exiting the nozzle with a looped around two rolls endless belt to the cooling roller. Such a plant is for example in EP 1 285 741 B1 described.

Advantages of the invention:

• • The invention Barrier film is weather-resistant without additional weather protection.
• The barrier film according to the invention is halogen-free.
• • The barrier film according to the invention has a high barrier to water vapor and oxygen (<0.1 g / (m ² d)).
• The barrier film according to the invention protects underlying layers from UV radiation, independently of the composition of the SiO _x layer.
• The barrier film according to the invention has a partial discharge voltage of more than 1,000V.

The carrier layer

When Carrier layer are preferably coextruded films Polymethylmethacrylate (PMMA) or impact-resistant PMMA (sz-PMMA) and polyolefins or polyesters. The carrier layer has a thickness of 20 microns to 500 microns, preferably The thickness is 50 microns to 400 microns and very special preferably at 200 microns to 300 microns. The PMMA layer the carrier layer has a thickness of 1 μm to 200 μm, preferably from 10 μm to 100 μm, more preferably from 15 microns to 80 microns.

The Notation "(meth) acrylate" means in the context the invention acrylate and / or methacrylate.

Instead of PMMA can also be a coextrudate of PMMA and PVDF or a blend used by PMMA and PVDF. Then, however, the advantage goes the halogen freedom lost. The polyolefin layer has a thickness from 19 μm to 499 μm, preferably 100 μm to 300 microns, more preferably from 150 microns to 250 μm. The adhesion promoter has a thickness of 1 μm to 100 μm, preferably from 5 to 50 μm, especially preferably from 10 to 40 .mu.m. It consists of copolymers, which consist of different polar parts. Preferred are Copolymers of polyolefins and (meth) acrylates, particularly preferred are copolymers of ethylene and methacrylate.

UV stabilizers and radical scavengers

According to the invention Light stabilizers are added to the carrier layer. Under Sunscreens should UV absorbers, UV stabilizers and radical scavengers be understood.

optional contained UV protectants are z. B. derivatives of benzophenone, its substituents such as hydroxyl and / or alkoxy groups are usually in 2- and / or 4-position. These include 2-hydroxy-4-n-octoxybenzophenone, 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2-hydroxy-4-methoxybenzophenone. Furthermore, substituted benzotriazoles are used as UV protection additive very suitable, especially 2- (2-hydroxy-5-methylphenyl) benzotriazole, 2- [2-hydroxy-3,5-di- (alpha, alpha-dimethyl-benzyl) phenyl] benzotriazole, 2- (2-hydroxy-3,5-di-t-butylphenyl) benzotriazole, 2- (2-hydroxy-3, 5-butyl-5-methylphenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-3 , 5-di-t-butylphenyl) -5-chlorobenzotriazole, 2- (2-hydroxy-3,5-di-t-amylphenyl) -benzotriazole, 2- (2-hydroxy-5-t-butylphenyl) -benzotriazole, 2- (2-hydroxy-3-sec-butyl-5-t-butylphenyl) benzotriazole and 2- (2-hydroxy-5-t-octylphenyl) benzotriazole, Phenol, 2,2'-methylenebis [6- (2H-benztriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl)] counting.

Next The benzotriazoles can also be a UV absorber of the class of 2- (2'-hydroxyphenyl) -1,3,5-triazines, such as phenol, 2- (4,6-diphenyl-1,2,5-triazin-2-xy) -5- (hexyloxy), be used.

Farther usable UV protectants are 2-cyano-3,3-diphenylacrylsäureethylester, 2-Ethoxy-2'-ethyl-oxalic bisanilide, 2-ethoxy-5-t-butyl-2'-ethyl-oxalic acid bisanilide and substituted benzoic acid phenyl esters.

The sunscreen or UV protection agents may be present as low molecular weight compounds, as indicated above, in the polymethacrylate compositions to be stabilized. But it can also UV-absorbing groups in the matrix polymer molecules covalently after copolymerization with polymerizable UV absorption compounds, such as. As acrylic, methacrylic or allyl derivatives of benzophenone or Benztriazolderivaten be bound. The proportion of UV protection agents, which may also be mixtures of chemically different UV protection agents, is generally from 0.01 to 10% by weight, in particular from 0.01 to 5% by weight, in particular from 0.02 to 2 wt .-% based on the (meth) acrylate copolymer.

Examples of radical scavengers / UV stabilizers are sterically hindered amines, which are known by the name HALS (Hindered Amine Light Stabilizer). They can be used for the inhibition of aging in paints and plastics, especially in polyolefin plastics ( Kunststoffe, 74 (1984) 10, pp. 620-623 ; Paint + lacquer, 96 vintage, 9/1990, pp. 689-693 ). The stabilizing effect of the HALS compounds is due to the tetramethylpiperidine group contained therein. This class of compounds may be both unsubstituted on the piperidine nitrogen and substituted with alkyl or acyl groups. The sterically hindered amines do not absorb in the UV range. They catch formed radicals, which the UV absorbers can not do. Examples of stabilizing HALS compounds which can also be used as mixtures are:
Bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro (4,5) decane-2,5-dione, bis (2,2,6,6-tetramethyl-4-piperidyl) succinate, poly (N-β-hydroxyethyl-2,2,6,6-tetramethyl-4-) hydroxy-piperidine-succinic acid ester) or bis (N-methyl-2,2,6,6-tetramethyl-4-piperidyl) sebacate.

Particularly preferred UV-absorbers are, for example, Tinuvin ^® 234, Tinuvin ^® 360, Chimasorb ^® 119 or Irganox ^® 1076th

Applied are the radical scavenger / UV stabilizers in the inventive Polymer blends in amounts of 0.01 to 15 wt .-%, especially in Amounts of 0.02 to 10 wt .-%, in particular in amounts of 0.02 to 5 wt .-% based on the (meth) acrylate copolymer.

Of the UV absorber is preferred in the PMMA layer, but it can also be contained in the polyolefin or polyester layer.

The Carrier layer has a transparency of more than 80%, preferably more than 85%, particularly preferably more than 90% in the wavelength range of> 300 nm, preferred 350 to 2000 nm, more preferably 380 to 800 nm.

The Carrier layer also has a sufficient Layer thickness to ensure the partial discharge voltage of 1,000 volts. These are, for example, PMMA 250 μm or PE or PP 210 μm. For combinations of materials is the necessary Layer thickness between these values.

Impact-modified poly (meth) acrylate plastic

Of the impact-modified poly (meth) acrylate plastic from 20% to 80%, preferably from 30% to 70%, by weight of one Poly (meth) acrylate matrix and 80 wt .-% to 20 wt .-%, preferably 70 wt .-% to 30 wt .-% elastomer particles having an average particle diameter from 10 to 150 nm (measurement, for example, by the ultracentrifuge method).

Prefers For example, the elastomer particles dispersed in the poly (meth) acrylate matrix have one Core with a soft elastomer phase and a bonded thereto Hard phase up.

Of the Impact modified poly (meth) acrylate plastic (szPMMA) consists of a proportion of matrix polymer polymerized from at least 80 wt .-% units of methyl methacrylate and optionally 0 to 20 wt .-% units of copolymerizable with methyl methacrylate Monomers and distributed in the matrix proportion of impact modifiers based on crosslinked poly (meth) acrylates

The matrix polymer consists in particular of 80 to 100, preferably 90-99.5 wt .-%, of free-radically polymerized methyl methacrylate units and optionally 0-20, preferably 0.5-10 wt .-% of other free-radically polymerizable comonomers , z. B. C ₁ - to C ₄ alkyl (meth) acrylates, in particular methyl acrylate, ethyl acrylate or butyl acrylate. The average molecular weight M _w (weight average) of the matrix is preferably in the range from 90,000 g / mol to 200,000 g / mol, in particular 100,000 g / mol to 150,000 g / mol (determination of M _w by gel permeation chromatography with reference to polymethyl methacrylate as calibration standard) , The determination of the molecular weight M _w can be carried out, for example, by gel permeation chromatography or by scattered light method (see, for example, US Pat. BHF Mark et al., Encyclopedia of Polymer Science and Engineering, 2nd. Edition, Vol. 10, pages 1 ff., J. Wiley, 1989 ).

Preferred is a copolymer of 90 to 99.5 wt .-% of methyl methacrylate and 0.5 to 10 wt .-% methyl acrylate. Vicat softening temperatures VET ( ISO 306-650 ) can be in the range of min at least 90, preferably from 95 to 112 ° C.

The impact modifier

The Polymethacrylate matrix contains an impact modifier, which z. B. a two- or dreischalig built impact modifier can be.

Impact modifiers for polymethacrylate plastics are well known. Production and construction of impact-modified polymethacrylate molding compositions are, for. In EP-A 0 113 924 . EP-A 0 522 351 . EP-A 0 465 049 and EP-A 0 683 028 described.

impact modifiers

In The polymethacrylate matrix is 1 wt% to 30 wt%, preferably From 2% by weight to 20% by weight, particularly preferably from 3% by weight to 15% by weight, in particular from 5% to 12% by weight of an impact modifier, which is an elastomeric phase of crosslinked polymer particles, contain. The impact modifier is in known manner by bead polymerization or by emulsion polymerization receive.

In the simplest case, crosslinked particles obtainable by means of bead polymerisation have an average particle size in the range from 10 to 150 nm, preferably 20 to 100, in particular 30 to 90 nm. These usually consist of at least 40, preferably 50-70 Wt .-% of methyl methacrylate, 20 to 40, preferably 25 to 35 wt .-% butyl acrylate and 0.1 to 2, preferably 0.5 to 1 wt .-% of a crosslinking monomer, for. B. a polyfunctional (meth) acrylate such. B. allyl methacrylate and optionally other monomers such. B. 0 to 10, preferably 0.5 to 5 wt .-% of C ₁ -C ₄ alkyl methacrylates, such as ethyl acrylate or butyl methacrylate, preferably methyl acrylate, or other vinyl polymerizable monomers such. Styrene.

Preferred impact modifiers are polymer particles which may have a two- or three-layer core-shell structure and are obtained by emulsion polymerization (see, for example, US Pat. EP-A 0 113 924 . EP-A 0 522 351 . EP-A 0 465 049 and EP-A 0 683 028 ). However, suitable particle sizes of these emulsion polymers must, for the purposes of the invention, be in the range of 10-150, preferably 20 to 120 nm, more preferably 50-100 nm.

One three-layered or three-phase construction with one core and two Bowls can be made as follows. An innermost (hard) shell can z. B essentially of methyl methacrylate, small proportions of comonomers, such as. Ethyl acrylate and a crosslinker fraction, z. As allyl methacrylate, exist. The middle (soft) shell can z. B. from butyl acrylate and optionally styrene, while the outermost (hard) shell in the essentially corresponds to the matrix polymer, whereby the Compatibility and good connection to the matrix causes becomes. The polybutyl acrylate content of the impact modifier is crucial for the impact-like effect and is preferably in the range of 20 to 40 wt .-%, more preferably in the range of 25 to 35 wt .-%.

toughened Polymethacrylate molding compounds

in the Extruders can use the impact modifier and matrix polymer to impact-modified polymethacrylate molding compositions be mixed in the melt. The discharged material becomes usually initially cut into granules. This can by extrusion or injection molding into moldings, as plates or injection molded parts are further processed.

Two-phase impact modifier according to EP 0 528 196 A1

• a1) 10 Gew.-% bis 95 Gew.-% einer zusammenhängenden Hartphase mit einer Glasübergangstemperatur T_mg über 70°C, aufgebaut aus
• a11) 80 Gew.-% bis 100 Gew.-% (bezogen auf a1) Methylmethacrylat und
• a12) 0 bis 20 Gew.-% eines oder mehrerer weiterer ethylenisch ungesättigter, radikalisch polymerisierbarer Monomeren, und
• a2) 90 bis 5 Gew.-% einer in der Hartphase vorteilten Zähphase mit einer Glasübergangstemperatur T_mg unter –10°C, aufgebaut aus
• a21) 50 bis 99,5 Gew.-% eines C₁-C₁₀-Alkylacrylats (bezogen auf a2)
• a22) 0,5 bis 5 Gew.-% eines vernetzenden Monomeren mit zwei oder mehr ethylenisch ungesättigten, radikalisch polymerisierbaren Resten, und
• a23) gegebenenfalls weiteren ethylenisch ungesättigten, radikalisch polymerisierbaren Monomeren,

wobei wenigstens 15 Gew.-% der Hartphase a1) mit der Zähphase a2) kovalent verknüpft sind.Preferred, in particular for film production, but not limited to this becomes, in principle, from EP 0 528 196 A1 known system that is a two-phase, impact-modified polymer is made of:

• a1) 10 wt .-% to 95 wt .-% of a continuous hard phase having a glass transition temperature T _mg above 70 ° C, built up from
• a11) 80 wt .-% to 100 wt .-% (based on a1) of methyl methacrylate and
• a12) 0 to 20% by weight of one or more further ethylenically unsaturated, radically polymerizable monomers, and
• a2) 90 to 5 wt .-% of an advantageous in the hard phase toughening phase having a glass transition temperature T _mg below -10 ° C, built up from
• a21) from 50 to 99.5% by weight of a C ₁ -C ₁₀ -alkyl acrylate (based on a2)
• a22) from 0.5 to 5% by weight of a crosslinking monomer having two or more ethylenically unsaturated, radically polymerizable radicals, and
• a23) optionally further ethylenically unsaturated, free-radically polymerizable monomers,

wherein at least 15% by weight of the hard phase a1) is covalently linked to the toughening phase a2).

The biphasic impact modifier can be produced by a two-stage emulsion polymerization in water, such as. In DE-A 38 42 796 described. In the first stage, the toughening phase a2) is generated, leading to at least 50, before Preferably, more than 80 wt .-%, is composed of lower alkyl acrylates, resulting in a glass transition temperature T _{mg of} this phase of below -10 ° C. As crosslinking monomers a22) are (meth) acrylic esters of diols, such as ethylene glycol dimethacrylate or 1,4-butanediol dimethacrylate, aromatic compounds having two vinyl or allyl groups, such as divinylbenzene, or other crosslinkers having two ethylenically unsaturated, radically polymerizable radicals, such as , As allyl methacrylate as a graft crosslinker used. Examples of crosslinkers containing three or more unsaturated, radically polymerizable groups, such as allyl groups or (meth) acrylic groups, include triallyl cyanurate, trimethylolpropane triacrylate and trimethacrylate, and pentaerythritol tetraacrylate and tetramethacrylate. Further examples are in this US 4,513,118 specified.

The under a23) mentioned ethylenically unsaturated, radically polymerizable monomers may be, for example, acrylic or methacrylic acid and their alkyl esters with 1-20 Carbon atoms, if not yet mentioned, where the alkyl radical is linear, may be branched or cyclic. Furthermore, a23) more radically polymerizable aliphatic comonomers which react with the Alkyl acrylates a21) are copolymerizable include. However, they should significant proportions of aromatic comonomers, such as styrene, alpha-methylstyrene or vinyl toluene are excluded because they - especially in weathering - to undesirable properties the molding compound A lead.

In the first stage toughening phase, attention must be paid to the particle size adjustment and nonuniformity. The particle size of the toughening phase depends essentially on the concentration of the emulsifier. Advantageously, the particle size can be controlled by the use of a seed latex. Particles having a weight average particle size of less than 130 nm, preferably less than 70 nm, and a particle size inconsistency U ₈₀ less than 0.5, (U ₈₀ is determined from an integral consideration of the particle size distribution determined by ultracentrifugation U ₈₀ = ((r ₉₀ -r ₁₀ ) / r ₅₀ ] -1, where r ₁₀ , r ₅₀ , r ₉₀ = mean integral particle radius for which 10, 50, 90% of the particle radii are below and 90, 50 , 10% of the particle radii are above this value), preferably below 0.2, are achieved with emulsifier concentrations of 0.15 to 1.0% by weight, based on the water phase, this applies in particular to anionic emulsifiers, such as, for example Particularly preferred alkoxylated and sulfated paraffins are used as polymerization initiators, for example 0.01 to 0.5% by weight of alkali metal or ammonium peroxodisulfate, based on the water phase, and the polymerization is initiated at temperatures of 20 to 100 ° C. Preference is given to using redox systems, for example a combination of 0.01 to 0.05% by weight of organic hydroperoxide and 0.05 to 0.15% by weight of sodium hydroxymethylsulfinate, at temperatures of 20 to 80 ° C.

The with the toughening phase a2) covalently bonded to at least 15% by weight Hard phase a1) has a glass transition temperature of at least 70 ° C and can be made up exclusively of methyl methacrylate be. Comonomers a12) can be up to 20% by weight of a or several other ethylenically unsaturated, free-radical polymerizable monomer may be contained in the hard phase, wherein Alkyl (meth) acrylates, preferably alkyl acrylates having 1 to 4 carbon atoms, be used in amounts such that the above Glass transition temperature is not exceeded.

The Polymerization of the hard phase a1) proceeds in a second Stage also in emulsion using the usual Auxiliaries, such as those for the polymerization of Toughening phase a2).

In a preferred embodiment, the hard phase contains low molecular weight and / or copolymerized UV absorbers in amounts of 0.1 to 10 wt .-%, preferably 0.5-5 wt .-%, based on A as a component of the comonomer components a12) in the hard phase. Exemplary of the polymerizable UV absorbers, as used inter alia in the U.S. 4,576,870 2- (2'-hydroxyphenyl) -5-methacrylamidobenzotriazole or 2-hydroxy-4-methacryloxybenzophenone may be mentioned. Low molecular weight UV absorbers may be, for example, derivatives of 2-hydroxybenzophenone or of 2-hydroxyphenylbenzotriazole or salicylic acid phenylester. In general, the low molecular weight UV absorbers have a molecular weight of less than 2 × 10 ³ (g / mol). Particularly preferred are UV absorbers with low volatility at the processing temperature and homogeneous miscibility with the hard phase a1) of the polymer A.

The barrier layer

The barrier layer is applied to the polyolefin layer of the carrier layer and preferably consists of inorganic oxides, for example SiO _x or AlO _x . For the exact layer structure see exemplary embodiments.

As SiO _x layers are preferably layers with the ratio of silicon and oxygen of 1: 1 to 1: 2, more preferably 1: 1.3 to 1: 1.7 use. The layer thickness is 5-300 nm, preferably 10-100 nm, particularly preferably 20-80 nm.

As AlO _x layers preferably find layers with the ratio of aluminum and oxygen from 2: 3 use. The layer thickness is 5-300 nm, preferably 10-100 nm, particularly preferably 20-80 nm.

For x, in the case of AlOx, a range of 0.5 to 1.5 applies; preferably from 1 to 1.5 and most preferably from 1.2 to 1.5 (where x = 1.5 Al ₂ O ₃ ).

The Inorganic oxides can be obtained by physical vacuum deposition (Electron beam or thermal process), magnetron sputtering or chemical vacuum deposition. A flame, Plasma or corona pretreatment is also possible.

application

These Barrier film can be used in the packaging industry, display technology, of organic photovoltaics, in thin-film photovoltaics, used in crystalline silicon modules as well as for organic LEDs become.

embodiment

1 shows the schematic structure of the film.

On a transparent and weather-resistant carrier layer ( 1 ) (preferably a coextrudate of PMMA or impact-modified PMMA with a polyolefin or a polyester) is an inorganic barrier layer ( 2 ) (preferably SiO _x or AlO _x ) applied. The carrier layer ( 1 ) is characterized by the fact that it contains a UV absorber in the PMMA layer.

Process:

• 1. Coextrusion of the carrier layer ( 1 )
• 2. Vacuum coating (PVD, CVD) of the carrier layer ( 1 )

Measurement of the barrier of the invention foil

The measurement of the water vapor permeability of the film system is carried out after ASTM F-1249 at 23 ° C / 85% rel. Humidity. (WVTR)

The measurement of the oxygen permeability occurs after ISO 15105-2 ( DIN 53380 T3 ) at 23 ° C / 50% rel. Humidity.

The measurement of the partial discharge voltage occurs after DIN 61730-1 and IEC 60664-1 ,

The measurement of the optical transmission takes place after ISO 13468-2 ,

Examples

Comparative Example:

A foil according to the prior art ( EP 1 018 166 61 ), z. B. SiOx-coated ETFE with 100 micron layer thickness has a barrier of 0.5 g / (m ² d).

A film according to the invention with a layer thickness of 300 μm of the carrier layer has a barrier between 0.01 and 0.1 g / (m ² d) (see Example 1).

example 1

• Carrier layer: PMMA layer: impact-resistant PMMA, layer thickness: 20 μm, contains 2% UV absorber Cesa Light ^® GXUVA006. Adhesion promoter: Elvaloy 1130 EAC (DuPont), layer thickness: 30 μm, polyolefin layer: PE Dowlex SC2108 G, layer thickness: 30 μm.
• Barrier layer: Al ₂ O ₃ , layer thickness 40 nm, applied by means of magnetron sputtering.

Measured values Example 1

• WVTR: 0.05 g / (m ² / d)
• Transmission: 86.6% at> 380 nm
• Partial discharge voltage: 1,250 V

Example 2

• Backing layer: PMMA layer: coextrudate of PMMA and impact-resistant PMMA, film thickness 80 microns, 1.5% UV absorber Tinuvin ^® contains 360 bonding agent layer: Bynel CXA 38E536, film thickness: 30 microns, polyolefin layer: PE Dowlex NG 5066 G
• Barrier layer: SiO _1.7 , layer thickness 80 nm, applied by means of magnetron sputtering.

Measured values Example 2

• WVTR: 0.04 g / (m ² / d)
• Transmission: 86.4% at> 380 nm
• Partial discharge voltage: 1,250 V

1

backing

2

barrier layer

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 3842796 A1 [0002]
• DE 102005019669 A1 [0004]
• - EP 911148 [0005]
• EP 271068 [0006]
• - DE 10010533 [0007, 0009]
• - DE 4337062 [0008]
• JP 9-193189 H [0009]
• - JP 10025357 A [0012]
• - JP 07074378 A [0012]
• - EP 1018166 B1 [0012, 0012]
• WO 94/29106 [0013]
• DE 10260067 A1 [0018]
• - EP 1285741 B1 [0021]
• - EP 0113924 A [0042, 0045]
• - EP 0522351 A [0042, 0045]
• EP 0465049 A [0042, 0045]
• - EP 0683028 A [0042, 0045]
• EP 0528196 A1 [0047, 0048]
• - DE 3842796 A [0049]
• US 4513118 [0049]
• US 4576870 [0054]
• - EP 101816661 [0067]

Cited non-patent literature

• U. Moosheimer, Galvanotechnik 90 No. 9, 1999, p. 2526-2531 [0014]
• Amberg-Schwab et al., Journal of Sol-Gel Sciene and Technology 1/2 (1998), p. 141-146 [0017]
• - Kunststoffe, 74 (1984) 10, pp. 620 to 623 [0030]
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• BHF Mark et al., Encyclopedia of Polymer Science and Engineering, 2nd. Edition, Vol. 10, pages 1 et seq., J. Wiley, 1989 [0039]
• - ISO 306-650 [0040]
• ASTM F-1249 [0063]
• - ISO 15105-2 [0064]
• - DIN 53380 T3 [0064]
• - DIN 61730-1 [0065]
• - IEC 60664-1 [0065]
• - ISO 13468-2 [0066]

Claims (15)

Barrier film, consisting of a weather-resistant Carrier layer, and an inorganic oxide layer, wherein the backing layer is a coextrudate of (meth) acrylate and Polyolefin or polyester is and on the polyolefin or polyester side an inorganic, transparent barrier layer is applied. Barrier film according to claim 1, characterized in that that it is halogen-free. Barrier film according to claim 1, characterized in that that it has a partial discharge voltage of at least 1000V. Barrier film according to claim 1, characterized in that that they have a transparency of more than 80% in the range of more than 300 nm. Process for the preparation of the barrier film, characterized characterized in that PMMA or sz-PMMA with a polyolefin or Polyester layer is coextruded. Process for the preparation of the barrier film, characterized characterized in that PMMA or sz-PMMA with a polyolefin or Polyester layer is coextruded on a sleeve touch system. Process for the preparation of the barrier film, characterized in that the one produced according to claim 5 or 6 Film by means of physical vacuum evaporation with an inorganic Barrier is equipped. Process for the preparation of the barrier film, characterized in that the one produced according to claim 5 or 6 Foil by physical vacuum evaporation of SiOx with a inorganic barrier is equipped. Process for the preparation of the barrier film, characterized in that the one produced according to claim 5 or 6 Film by physical vacuum evaporation of alumina equipped with an inorganic barrier. Process for the preparation of the barrier film, characterized characterized in that in the film produced in claim 7 SiOx is vaporized by electron beam. Process for the preparation of the barrier film, characterized characterized in that in the film produced in claim 7 alumina is vaporized by electron beam. Process for the preparation of the barrier film, characterized characterized in that in the film produced in claim 7 SiOx is thermally evaporated. Process for the preparation of the barrier film, characterized characterized in that in the film produced in claim 7 alumina is thermally evaporated. Use of barrier films according to claim 1 in the packaging industry, the display technology and for organic LEDs. Use of barrier films according to claim 1 in the organic photovoltaic, in the thin-film photovoltaic and in crystalline silicon modules.