DE10035327A1 - Opaque biaxially oriented polyester film with at least one adhesion-promoted surface includes a flame retardant and a cycloolefin copolymer - Google Patents

Abstract

An opaque biaxially-oriented polyester film (I) with at least one adhesion-promoted surface includes: (A) a flame retardant; and (B) at least one layer containing 2-60 wt.% of a cycloolefin copolymer (COC) with a glass transition temperature (Tg) of 70-270 [deg]C. An independent claim is also included for a process for producing the film, comprising: (a) (co)extruding melt(s) corresponding to the individual layer(s) of the film; (b) withdrawing the film over one or more rolls; (c) biaxially stretching the film; (d) optionally coating the film; (e) thermofixing the film; and (f) optionally subjecting a surface of the film to corona discharge or flame treatment.

Description

The present invention relates to an opaque, flame-retardant, biaxially oriented Polyester film that contains at least one flame retardant, the at least one Layer comprising a polyester raw material and a cycloolefin copolymer (COC) contains and has at least one surface that adheres well to others Has polymer or metal layers or printing inks. The invention further relates to a process for producing the polyester film and its use.

White, biaxially oriented polyester films are known. In addition, these are slides easily flammable.

DE-A 23 53 347 describes a process for producing a single or multilayer, milky polyester film described, which is characterized is that a mixture of particles of a linear polyester with 3 to 27 wt .-% a homopolymer or copolymer of ethylene or propylene, which Extruded mixture as a film, quenching the film and stretching it vertically mutually biaxially oriented directions and heat-set the film. A disadvantage of the method is that it is incurred during the production of the film Regenerate (essentially a mixture of polyester raw material and ethylene or Propylene copolymer) can no longer be used, otherwise the film discolored or turns yellow. The process is therefore uneconomical. In addition, the film not flame retardant and has clearly too high roughness and therefore has a very matt appearance (very low gloss), which for many purposes is undesirable.  

EP-A 0 300 060 describes a single-layer polyester film which, apart from Polyethylene terephthalate still 3 to 40 wt .-% of a crystalline propylene polymer and contains 0.001 to 3% by weight of a surfactant. The surfactant causes the number of vacuoles in the film to increase while decreasing in size to the desired extent. This will create a achieved higher opacity and a lower density of the film. Another disadvantage is that the regrind produced in the production of the film (essentially a Mixture of polyester raw material and propylene homopolymer) is no longer used can otherwise be discolored yellow. The procedure is now uneconomical. In addition, the film is not flame retardant and has one poor adhesion to printing inks, reprographic and other functional layers such as B. metal layers, high roughness and thus has a very matt appearance (very low gloss), which is undesirable for many applications.

EP-A 0 360 201 describes an at least two-layer polyester film which has a base layer with fine vacuoles, the density of which is between 0.4 and 1.3 kg / dm ³ and at least one cover layer, the density of which is greater than 1. 3 kg / dm ³ . The vacuoles are achieved by adding 4 to 30% by weight of a crystalline propylene polymer and then biaxially stretching the film. The additional cover layer improves the manufacturability of the film (no streaking on the surface of the film), the surface tension is increased and the roughness of the laminated surface can be reduced. It is also disadvantageous here that the regrind obtained in the production of the film (essentially a mixture of polyester raw material and propylene homopolymer) can no longer be used, since otherwise the film is discolored yellow. The process is therefore uneconomical. In addition, the film is not flame retardant and still has poor adhesion to printing inks, polymer and metal layers, high roughness and therefore has a matt appearance (low gloss), which is undesirable for many applications.

EP A 0 795 399 describes an at least two-layer polyester film which has a base layer with fine vacuoles, the density of which is between 0.4 and 1.3 kg / dm ³ and at least one cover layer, the density of which is greater than 1.3 kg / dm ³ . The vacuoles are created by adding 5 to 45% by weight of a thermoplastic polymer to the polyester raw material in the base layer and then biaxially stretching the film. Polypropylene, polyethylene, polymethylpentene, polystyrene or polycarbonate are mentioned as thermoplastic polymers, polypropylene being the preferred thermoplastic polymer. The additional cover layer improves the manufacturability of the film (no streaking on the surface of the film), increases the surface tension and the roughness of the laminated surface can be adapted to the respective requirements. A further modification of the film in the base layer and / or in the outer layers with white pigments (usually TiO ₂ ) and / or with optical brighteners enables the film properties to be adapted to the respective application requirements. However, it is also disadvantageous here that the manufacture of the. Regenerate film (essentially a mixture of polyester raw material and the additive raw material) can no longer be used, since otherwise the color of the film is changed indefinitely, which is undesirable for many applications. The process is therefore uneconomical. In addition, the film is not flame retardant and has poor adhesion to printing inks, reprographic and other functional layers, such as. B. metal layers, high roughness and thus have a matt appearance (low gloss), which is undesirable for many applications.

DE-A 195 40 277 describes a single-layer or multilayer polyester film which has a base layer with fine vacuoles, the density of which lies between 0.6 and 1.3 kg / dm ³ and has a birefringence in the plane of -0.02 to 0.04 is sufficient. The vacuoles are created by adding 3 to 40% by weight of a thermoplastic resin to the polyester raw material in the base layer and then biaxially stretching the film. Thermoplastic resins include polypropylene, polyethylene, polymethylpentene, cyclic olefin polymers, polyacrylic resins, polystyrene or polycarbonate, with polypropylene and polystyrene being preferred raw materials. By adhering to the specified limits for the birefringence of the film, the claimed film is distinguished in particular by good tear strength and good isotropy properties. A further disadvantage is that the regrind obtained in the production of the film can no longer be used, since otherwise the color of the film is changed indefinitely, which is undesirable for many applications. The process is therefore uneconomical. In addition, the film is not flame retardant and has poor adhesion to printing inks, reprographic and other functional layers, such as. B. metal layers; high roughness and thus have a matt appearance (low gloss), which is undesirable for many applications.

EP-A 0144 878 describes films with a copolyester coating, that have good adhesion to metals. The slides described there have good adhesion to metals, but they are not opaque and not flame resistant.

EP-A 0 144 948 describes films with a crosslinked acrylic Adhesion coating described that have good adhesion to photosensitive have reprographic coatings. The slides described there have indeed have good reprographic adhesion and regenerability, but they are not opaque and not flame retardant.

EP A 0 884 348 describes films with an adhesion promoter layer which have good adhesion to water-soluble or hydrophilic layers. These The films described adhere well to watery applications Layers, but they are not opaque and not flame retardant.  

The above films do not contain any flame retardants, so that neither the films still the articles made from them for outdoor use, where a Fire protection or flame retardancy is required. Meet the foils not the fire tests according to DIN 4102 part 2 and part 1 as well as the UL test 94.

In EP-A-0 620 245 foils are described with regard to their thermal Stability are improved. These films contain antioxidants; which suitable are to trap radicals formed in the film and to break down the peroxide formed. However, this document suggests how to achieve the opacity of such foils not to be removed.

DE-A 23 46 787 describes a flame-retardant raw material. In addition to the raw material, the use of the raw material for the production of films and fibers is also described. However, the following deficits emerged in the production of films from this phospholane-modified raw material:

• - The film did not have the required opacity.
• - The raw material was very sensitive to hydrolysis and had to be pre-dried very well become. When drying the raw material with industrial dryers, the Raw material, so that a film can only be produced under the most difficult conditions was.
• - The films produced under extreme and uneconomical conditions embrittled when exposed to temperature, d. H. the mechanical properties fell sharply due to embrittlement, making the film unusable was. This embrittlement already occurred after 48 hours of thermal stress.

The object of the present invention was therefore to provide an opaque, flame retardant polyester film, which is characterized by a high gloss, in particular through good adhesion to other layers and an improved, economic producibility, d. H. low manufacturing costs, distinguished without sacrificing the to have the above-mentioned disadvantageous properties. In particular, should  be guaranteed that the regenerate that is inherent in the manufacturing process in a concentration of preferably 10 to 70 wt .-%, based on the Total weight of the film, can be reused without the physical properties of the film are significantly affected. In particular, the addition of regenerate should not cause any discolouration or The film turns yellow.

The economic production includes that the raw materials or Raw material components needed to manufacture the flame retardant film are dried with industrial dryers that meet the standard of technology can be. It is essential that the raw materials do not stick together and not thermally be dismantled. These state of the art industrial dryers include Vacuum dryer, fluid bed dryer, fluid bed dryer, fixed bed dryer (Tower dryer). These dryers operate at temperatures between 100 and 170 ° C, where the flame retardant raw materials stick so that none Foil production is possible.

The raw material goes through one in the most gently drying vacuum dryer Temperature range from approx. 30 ° C to 130 ° C at a vacuum of 50 mbar. After that is a so-called drying in a hopper at temperatures of approx. 100-130 ° C and a residence time of 3 to 6 hours is required. This raw material sticks even here extreme.

A flame retardant effect means that the opaque film in a so-called Fire protection test the conditions according to DIN 4102 part 2 and especially the Conditions according to DIN 4102 part 1 fulfilled and in building material class B2 and in particular B1 of the flame retardant substances can be classified.

The film is also said to pass the UL test 94 "Vertical Burning Test for Flammability of Plastic Material "so that it can be classified in class 94 VTM-0.  

This means that the film will not work 10 seconds after the Bunsen burner is removed burns more, no glow is observed after 30 seconds and no dripping is detected.

The task is solved by an opaque, flame-retardant, biaxially oriented Polyester film with at least one base layer, the base layer being a Cycloolefin copolymer (COC) contains. The concentration of the COC is preferred from 2 to 60% by weight, based on the weight of the base layer. The The glass transition temperature of the cycloolefin copolymer (COC) is preferably in the Range from 70 to 270 ° C. In addition, the film contains at least one Flame retardant, the invention as a masterbatch in film production is metered directly. At least one surface of the film according to the invention way conveys.

Under an opaque, flame-retardant, biaxially oriented polyester film in the sense In the present invention, a film is referred to which has such strong light scattering shows that underlying patterns are not recognizable. The opacity of the film according to the invention is more than 55%, preferably more than 60% and particularly preferably more than 65%.

As a rule, the opaque, flame-retardant, biaxially oriented polyester films in the sense of the present invention knows. Under a white, flame-retardant, Biaxially oriented polyester film in the sense of the present invention becomes such Film that has a degree of whiteness of more than 70%, preferably more than 75% and particularly preferably of more than 80%.

In order to achieve the desired opacity of the film according to the invention preferably the proportion of the cycloolefin copolymer (COC) in the base layer be greater than 2%, otherwise the opacity is less than 55%. Is the Cycloolefin copolymer (COC) content, on the other hand, is greater than 60%  No longer produce film economically because it is no longer reliable lets stretch.

It is further preferred that the glass transition temperature of the used Cycloolefin copolymers (COC) is greater than 70 ° C. Otherwise (with a Glass transition temperature of less than 70 ° C) the raw material mixture is below Possibly more difficult to process (more difficult to extrude), the desired degree of whiteness may not be reached and the regrind used leads to a Film that may have an increased yellowing. On the other hand, it is Glass transition temperature of the selected cycloolefin copolymer (COC) higher than 270 ° C, the raw material mixture may no longer be in the extruder disperse sufficiently homogeneously. This would have a slide with it result in inhomogeneous properties.

In the preferred embodiment of the film according to the invention, the Glass transition temperature of the COCs used in a range from 90 to 250 ° C and in the particularly preferred embodiment in a range from 110 to 220 ° C.

Surprisingly, it was found that the addition of a Cycloolefin copolymers (COC) in the manner described above an opaque, glossy film can be made.

According to the amount and type of cycloolefin copolymer (COC) added the degree of whiteness and the opacity of the film can be set precisely and the respective Requirements are adjusted. With this measure it is possible to share with others to largely dispense with common white and opaque additives. Furthermore was it is very surprising that the surface roughness of the film is much less and so that the gloss of the film is much higher than with comparable films after State of the art. The additional one was also completely surprising  Effect that the regenerate is not like the polymeric additives according to the state of the art Technology that tends to discolour yellow.

All of the features described were unpredictable. This is all the more because z. B. COCs largely become the preferred polyester polyethylene terephthalate are incompatible, but as is well known, with similar stretching ratios and Drawing temperatures are oriented, such as polyethylene terephthalate. Under these A person skilled in the art would have expected that the inventive Manufacturing conditions no white, opaque film with high gloss can be produced can.

In particular in the preferred and the particularly preferred embodiments is characterized by a high / or. through a particularly high whiteness, a high / or. through a particularly high opacity and by a flame retardant, the color change of the film by the The amount of regeneration remains extremely low.

The film according to the invention has one or more layers. Single-layer Embodiments are like the COC-containing layer described below built up. Multi-layer embodiments are at least two-layer and always include the COC-containing layer and at least one further layer, wherein the COC-containing layer is the base layer, but also the intermediate or can form the cover layer of the multilayer film. In a preferred one In one embodiment, the COC-containing layer also forms the base layer of the film at least one, preferably with cover layers on both sides, where appropriate one or both sides of intermediate layers can be present. The Layer structure of the film is then z. B. A-B-C, where B is the base layer and A and C the Are cover layers that can be the same or different. In another preferred embodiment, the COC-containing layer also forms a Interlayer of the multilayer film. Further embodiments with COC-containing  Interlayers are built up of five layers and have COC-containing ones Base layer with COC-containing intermediate layers on both sides. In another Embodiment, the COC-containing layer in addition to the base layer, one or form cover layer (s) on both sides on the base or intermediate layer. The base layer For the purposes of the present invention, that layer which is preferably 50% to 100%, in particular 70 to 90%, of the total film thickness. The top layers are the layers that form the outer layers of the film.

The respective embodiment of the invention is a non-transparent, opaque, flame retardant film. Under non-transparent films are in the sense of Present invention understood such forms, the light transmission according to ASTM-D 1003-77 is below 95%, preferably below 75%.

The film according to the invention contains at least one flame retardant, which over the so-called master batch technology is metered in directly during film production, the concentration of the flame retardant in the range from 0.5 to 30.0% by weight, preferably from 1.0 to 20.0% by weight, based on the weight of the film. at The production of the masterbatch generally involves a ratio of Flame retardants for thermoplastic in the range from 60 to 40% by weight to 10 to 90% by weight respected.

Typical flame retardants include bromine compounds, chlorinated paraffins and other chlorine compounds, antimony trioxide, aluminum trihydrates, the Halogen compounds due to the resulting halogen-containing by-products are disadvantageous. Furthermore, the low light resistance is one of them equipped film in addition to the development of hydrogen halide in the event of a fire extremely disadvantageous.

Suitable flame retardants which are used according to the invention are for example organic phosphorus compounds such as carboxyphosphinic acids  Anhydrides and dimethyl methylphosphonate. It is essential to the invention that the organic phosphorus compound is soluble in the thermoplastic, otherwise the required optical properties, such as turbidity and yellowing, are not met become.

Since the flame retardants generally have a certain sensitivity to hydrolysis have, the additional use of a hydrolysis stabilizer may be useful.

As a hydrolysis stabilizer, phenolic stabilizers, alkali / Alkaline earth stearates and / or alkali / alkaline earth carbonates in amounts of 0.01 to 1.0% by weight based on the weight of the layer containing the flame retardant used. Phenolic stabilizers are used in an amount of 0.05 to 0.6% by weight, in particular 0.15 to 0.3 wt .-% based on the weight of the Flame retardant-containing layer and with a molecular weight of more than 500 g / mol prefers. Pentaerythrityl tetrakis-3- (3,5-di-tert-butyl-4-hydroxyphenyl) - Propionate or 1,3,5-trimethyl-2,4,6-tris (3,5-di-tertiary-butyl-4-hydroxybenzyl) benzene particularly advantageous.

In a preferred embodiment, the opaque flame-retardant film as a main component a crystallizable Polyethylene terephthalate and 1 wt .-% to 20 wt .-% of an organic im Polyethylene terephthalate-soluble organic phosphorus compound, preferably dimethyl Methylphosphonate as a flame retardant.

The COC-containing layer (the base layer) of the film according to the invention contains one thermoplastic polyester, preferably a polyester homopolymer, a COC and, if appropriate, further additives added in each case in effective amounts. in the in general, this layer preferably contains at least 20% by weight, preferably 40 up to 98% by weight, in particular 70 to 98% by weight, of thermoplastic polyester, based on the weight of the layer.  

Suitable thermoplastic polyesters for the base layer are preferably made of polyester Ethylene glycol and terephthalic acid (= polyethylene terephthalate, PET), from ethylene glycol and naphthalene-2,6-dicarboxylic acid (= polyethylene-2,6-naphthalate, PEN), from 1,4-bis hydroximethyl-cyclohexane and terephthalic acid (= poly-1,4-cyclohexane dimethylene terephthalate, PCDT) and from ethylene glycol, naphthalene-2,6-dicarboxylic acid and biphenyl-4,4'-dicarboxylic acid (= polyethylene-2,6-naphthalate bibenzoate, PENBB). Polyesters which are at least 90 mol% preferred at least 95 mol%, from ethylene glycol and terephthalic acid units or from Ethylene glycol and naphthalene-2,6-dicarboxylic acid units exist. The remaining Monomer units come from other aliphatic, cycloaliphatic or aromatic diols or dicarboxylic acids, such as z. B. in layer A (A = top layer 1) or layer C (C = top layer 2) of a multilayer film ABC (B = base layer) can occur.

Suitable other aliphatic diols are, for example, diethylene glycol, triethylene glycol, aliphatic glycols of the general formula HO- (CH ₂ ) _n OH, where n represents an integer from 3 to 6 (in particular propane-1,3-diol, butane-1,4- diol, pentane-1,5-diol and hexane-1,6-diol) or branched aliphatic glycols with up to 6 carbon atoms. Of the cycloaliphatic diols, cyclohexanediols (in particular cyclohexane-1,4-diol) may be mentioned. Suitable other aromatic diols correspond, for example, to the formula HO-C ₆ H ₄ -XC ₆ H ₄ -OH, where X is -CH ₂ -, -C (CH ₃ ) ₂ -, -C (CF ₃ ) ₂ -, -O -, -S- or -SO ₂ - stands. In addition, bisphenols of the formula HO-C ₆ H ₄ -C ₆ H ₄ -OH are also very suitable.

Other aromatic dicarboxylic acids are preferably benzenedicarboxylic acids, naphthalenedicarboxylic acids (for example naphthalene-1,4- or -1,6-dicarboxylic acid), biphenyl-x, x'-dicarboxylic acids (in particular biphenyl-4,4'-dicarboxylic acid), diphenylacetylene-x, x '-dicarboxylic acids (especially diphenylacetylene-4,4'-dicarboxylic acid) or stilbene-x, x'-dicarboxylic acids. Of the cycloaliphatic dicarboxylic acids, cyclohexanedicarboxylic acids (in particular cyclohexane-1,4-dicarboxylic acid) should be mentioned. Of the aliphatic dicarboxylic acids, the (C ₃ -C ₁₉ ) alkanedioic acids are particularly suitable, the alkane portion being straight-chain or branched.

The preparation of the polyester to be used according to the invention can, for. B. after the transesterification process. One starts from dicarboxylic acid esters and Diols, which with the usual transesterification catalysts, such as zinc, calcium, Lithium, magnesium and manganese salts are implemented. The intermediates are then in the presence of common polycondensation catalysts, such as Antimony trioxide or titanium salts, polycondensed. The production can be just as good by the direct esterification process in the presence of Polycondensation catalysts take place. You go straight from the Dicarboxylic acids and the diols.

According to the invention, the COC-containing layer or the film contains single-layer ones Embodiments of a cycloolefin copolymer (COC) in an amount of preferred at least 2.0% by weight, in particular 4 to 50% by weight and particularly preferably 6 to 40 % By weight, based on the weight of the layer equipped with COC or on the weight of the film in single-layer embodiments. It is very beneficial for the present invention when the cycloolefin copolymer (COC) used with the thermoplastic polyester, e.g. B. polyethylene terephthalate is not compatible and does not form a homogeneous mixture with it.

Cycloolefin polymers are generally homopolymers or copolymers which contain polymerized cycloolefin units and optionally acyclic olefins as comonomers. Cycloolefin polymers which contain 0.1 to 100% by weight, preferably 10 to 99% by weight, particularly preferably 50-95% by weight, in each case based on the total mass of the cycloolefin polymer, polymerized cycloolefin units are particularly suitable for the present invention , Particularly preferred are polymers which are composed of the monomers of the cyclic olefins of the formulas I, II, III, IV, V or VI:

In these formulas, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ^{8 are} independently the same or different and represent a hydrogen atom or a C ₁ -C ₃₀ hydrocarbon radical; or two or more of the radicals R ¹ to R ⁸ are cyclically linked, the same radicals in the different formulas having the same or different meaning. C ₁ -C ₃₀ hydrocarbon residues are preferably linear or branched C ₁ -C ₈ alkyl residues, C ₆ -C ₁₈ aryl residues, C ₇ -C ₂₀ alkylene aryl residues or cyclic C ₃ -C ₂₀ alkyl residues or acyclic C ₂ -C ₂₀ -alkenyl.

Optionally, the cycloolefin polymers according to the invention can contain 0 to 45% by weight, based on the total mass of the cyclocefin polymer, of polymerized units of at least one monocyclic olefin of the formula VII:

Herein n is a number of preferably 2 to 10.

The cycloolefin polymers can optionally contain 0 to 99% by weight, based on the total mass of the cycloolefin polymer, of polymerized units of an acyclic olefin of the formula VIII:

Here R ⁹ , R ¹⁰ , R ¹¹ and R ^{12 are,} independently of one another, identical or different and denote a hydrogen atom or C ₁ -C ₁₀ hydrocarbon radical, preferably a C ₁ -C ₈ alkyl radical or C ₆ -C ₁₄ aryl radical.

Also suitable in principle are cycloolefin polymers which are ring-opening  Polymerization of at least one of the monomers of the formulas I to VI and subsequent hydrogenation can be obtained.

Cycloolefin homopolymers are constructed from a monomer of the formulas I-VI. These cycloolefin polymers are less for the purposes of the present invention suitable. In particular, for the purposes of the present invention Cycloolefin copolymers (COC) suitable, which at least one cycloolefin Contain formulas I to VI and at least one comonomer. Preferred comonomers are acyclic olefins of formula VIII. In the foregoing as in the following these cycloolefin copolymers which can be used according to the invention are called COC. there preferred as acyclic olefins VIII are those which have 2 to 20 carbon atoms especially unbranched acyclic olefins with 2 to 10 carbon atoms such as for example ethylene, propylene and / or butylene. The proportion of polymerized units acyclic olefins of the formula VIII is up to 99% by weight, preferably 5 to 80% by weight, particularly preferably 10 to 60 wt .-%, based on the total weight of the respective cycloolefin copolymer.

Among the cycloolefin copolymers, those are particularly preferred polymerized units of polycyclic olefins with a norbornene structure, especially preferably contain norbornene, 5-methyl-norbornene or tetracyclododecene. Suitable monomers are also dimethyl octahydronaphthalene and cyclopentene. Cycloolefin copolymers (COC) which polymerized are also particularly preferred Contain units of acyclic olefins, especially ethylene. Again special norbornene / ethylene and tetracyclododecene / ethylene copolymers are preferred, which is 5 to 80% by weight, preferably 10 to 60% by weight, of acyclic olefin included (based on the weight of the copolymer).

The cycloolefin polymers described generally have Glass transition temperatures between -20 ° C and 400 ° C. Are for the invention preferably cycloolefin copolymers (COC) can be used, the one  Glass transition temperature of greater than 70 ° C, preferably greater than 90 ° C and have in particular greater than 110 ° C. The viscosity number (decalin, 135 ° C, DIN 53 728) is expediently between 0.1 and 200 ml / g, preferably between 50 and 150 ml / g.

The cycloolefin copolymers (COC) are produced by a heterogeneous process or homogeneous catalysis with organometallic compounds and is in a variety described by documents. Suitable catalyst systems based on Mixed catalysts made of titanium or vanadium compounds in connection with Aluminum organyls are described in DD 109 224, DD 237 070 and EP-A-0 156 464 described. EP-A-0 283 164, EP-A-0 407 870; EP-A-0 485 893 and EP-A-0 503 422 describe the production of cycloolefin copolymers (COC) with catalysts, based on soluble metallocene complexes. To the writings mentioned above Manufacturing process of cycloolefin polymers described is hereby expressly referred.

The cycloolefin copolymers are incorporated into the film either as pure granules or as granulated concentrates (masterbatch) by premixing the polyester granules or powder with the cycloolefin copolymer (COC) or the cycloolefin copolymer (COC) masterbatch and then feeding them to the extruder. The components are mixed further in the extruder and heated to processing temperature. It is expedient for the process according to the invention that the extrusion temperature is above the glass transition temperature T _{g of} the cycloolefin copolymer (COC), generally at least 5 ° C., preferably 10 to 180 ° C., in particular 15 to 150 ° C., above the glass transition temperature of the cycloolefin copolymer (COC).

In principle, the same can be used for the intermediate layers and for the cover layers Polymers are used as for the base layer. Preferably, the Cover layers made of a mixture of polymers, a copolymer or a  Homopolymers consist of ethylene-2,6-naphthalate units and ethylene terephthalate units included. Up to 30 mol% of the polymers can be made from others Comonomers (e.g. ethylene isophthalate units) exist.

The base layer and the other layers can additionally conventional additives such as Stabilizers, antiblocking agents and other fillers. You will be functional added to the polymer or the polymer mixture before melting. As Stabilizers are, for example, phosphorus compounds, such as phosphoric acid or Phosphoric acid ester used.

Typical antiblocking agents (also referred to as pigments in this context) are inorganic and / or organic particles, for example calcium carbonate, amorphous silica, pyrogenic silica, spherical silicon dioxide particles, talc, Magnesium carbonate, barium carbonate, calcium sulfate, barium sulfate, lithium phosphate, Calcium phosphate, magnesium phosphate, aluminum oxide, lithium fluoride, calcium, Barium, zinc or manganese salts of the dicarboxylic acids used, carbon black, titanium dioxide, Kaolin or cross-linked polymer particles, e.g. B. polystyrene or acrylate particles.

Mixtures of two or more different ones can also be used as additives Antiblocking agents or mixtures of antiblocking agents of the same composition, but different particle sizes can be selected. The particles can Polymers of the individual layers of the film in the most advantageous Concentrations, e.g. B. as a glycolic dispersion during polycondensation or can be added via masterbatches during extrusion. As particularly suitable have shown pigment concentrations of 0 to 25 wt .-% (based on the Weight of each layer). A detailed description of the appropriate Antiblocking agents can be found, for example, in EP-A-0 602 964.

If a color other than white is desired for the opaque film according to the invention, it can the desired shade by mixing in colorants or mixtures in  the polyester can be achieved. Both soluble dyes and insoluble ones can be used Color pigments are used.

According to the invention, at least one film surface is treated such that the contact angle with water is ≦ 64 °, preferably ≦ 62 °; in particular ≦ 60 °. This is preferably achieved by a corona or flame treatment, which usually follows the heat setting of the film. The treatment can also take place at other points in the film production process, for example before or after the longitudinal stretching. Alternatively or in addition to the surface treatment described above, the film can be coated on at least one of its surfaces with a functional coating, so that the coating on the finished film has a thickness of 5 to 2000 nm, preferably 20 to 500 nm, in particular 30 to 200 nm having. The coating is preferably applied in-line, ie during the film production process, expediently before transverse stretching. Application by means of the "reverse gravure-roll coating" method is particularly preferred, in which the coatings can be applied extremely homogeneously in layer thicknesses of up to 100 nm. Application by means of the Meyer-Rod process, with which greater coating thicknesses can be achieved, is also preferred. The coatings are preferably applied as solutions, suspensions or dispersions, particularly preferably as an aqueous solution, suspension or dispersion. The coatings mentioned give the film surface an additional function; for example, the film is sealable, printable, metallizable, sterilizable, antistatic or improve z. B. the aroma barrier or allow adhesion to materials that would otherwise not adhere to the film surface (z. B. photographic emulsions). Examples of substances / compositions which provide additional functionality: acrylic mates, as described, for example, in WO 94/13476, ethyl vinyl alcohols, PVDC, water glass (Na ₂ SiO ₄ ), hydrophilic polyester (5-Na-sulfoisophthalic acid-containing PET / IPA Polyesters as described, for example, in EP-A-0 144 878, US-A-4,252,885 or EP-A-0 296 620), polyvinyl acetates, as described, for example, in WO 94/13481, polyvinyl acetates, Polyurethanes, alkali or alkaline earth salts of C ₁₀ -C ₁₈ fatty acids, butadiene copolymers with acrylonitrile or methyl methacrylate, methacrylic acid, acrylic acid or their esters.

The substances / compositions mentioned are a dilute solution, emulsion or dispersion preferably as an aqueous solution, emulsion or dispersion on a or applied both film surfaces and then the solvent volatilized. If the coatings are applied in-line before transverse stretching, Usually the thermal treatment in the transverse stretching and subsequent is sufficient Heat fixation to volatilize the solvent and the coating too dry. The dried coatings then have layer thicknesses of 5 to 2000 nm preferably 20 to 500 nm, in particular 30 to 200 nm.

In a preferred embodiment of the invention, a copolyester coating is used to achieve better adhesion. The preferred coating copolyesters are obtained by polycondensing (α) isophthalic acid, (β) an aliphatic dicarboxylic acid having the formula

HOOC (CH ₂ ) _n COOH,

where n is in the range from 1 to 11,
(γ) a sulfomonomer containing an alkali metal sulfonate group on the aromatic part of an aromatic dicarboxylic acid and (δ) at least one aliphatic or cycloaliphatic alkylene glycol having about 2 to 11, preferably 2 to 8, in particular 2 to 6 carbon atoms. The total acid equivalents present should essentially correspond to the total glycol equivalents present on a molar basis.

It has been shown that the relative proportions of the components α, β, γ and δ which are used to produce the preferred copolyester coatings, crucial to achieving a coated film with satisfactory Liability. So should preferably z. B. isophthalic acid (component α) at least about 65 mol% be present as the acid component. The component is preferred  α pure isophthalic acid, which is present in an amount of about 70 to 95 mol%. For the component β applies that any acid with the formula mentioned is satisfactory Brings results, with adipic acid, azelaic acid, sebacic acid, malonic acid, Succinic acid, glutaric acid and mixtures of these acids are preferred. The desired amount within the range given is preferably 1 to 20 mol%, based on the acid components of the copolyester when the component β is included in the composition. That the component γ of the preferred Copolyester coating forming monomers should preferably be present in an amount of at least 5 mole% should be included in this system so that the primer with Water becomes dispersible. The amount of monomers is particularly preferably Components γ at about 6.5 to 12 mol%. The glycol component (δ) is approximate stoichiometric amount present.

In a further preferred embodiment of the invention, a Acrylic coating used to achieve better adhesion. The preferred acrylic copolymers used essentially consist of at least 50% by weight one or more polymerized acrylic and / or methacrylic monomers and 1 to 15% by weight of a copolymerizable comonomer which is in copolymerized state under the action of elevated temperature, if appropriate without the addition of a separate resinous crosslinking agent, to form is capable of intermolecular networking.

The acrylic component of the adhesion promoter copolymers is preferably present in an amount of 50 to 99 wt .-% and preferably consists of an ester of methacrylic acid, in particular an alkyl ester, the alkyl group of which contains up to ten carbon atoms, such as. B. the methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tertiary butyl, hexyl, 2-ethylhexyl, heptyl and n-octyl group. Acrylic copolymers which are derived from a lower alkyl acrylate (C ₁ to C ₄ ), in particular ethyl acrylate, together with a lower alkyl methacrylate result in particularly good adhesion between the polyester film and the reprographic coatings and matt coatings applied to it. Adhesion promoter copolymers made from an alkyl acrylate, e.g. B. ethyl acrylate or butyl acrylate, together with an alkyl methacrylate, e.g. B. methyl methacrylate, in particular in equal molar proportions and in a total amount of 70 to 95 wt .-%, used. The acrylate comonomer of such acrylic-IMethacrylic combinations is preferably present in a proportion of 15 to 65 mol% and the methacrylate comonomer is preferably present in a proportion which is generally 5 to 20 mol% greater than the proportion of the acrylate comonomer. The methacrylate is preferably contained in the combination in a proportion of 35 to 85 mol%.

To increase the resistance to solvents can optionally be used for training suitable comonomers of crosslinks are used, such as e.g. B. N- Methylolacrylamide, N-methylolmethacrylamide and the corresponding ethers; Epoxy materials such as B. glycidyl acrylate, glycidyl methacrylate and allyl glycidyl ether; Monomers containing carboxyl groups such. B. crotonic acid, itaconic acid or Acrylic acid; Anhydrides such as B. maleic anhydride or itaconic anhydride; Monomers containing hydroxyl groups such as. B. allyl alcohol and hydroxyethyl or Hydroxypropyl acrylate or methacrylate; Amides such as B. acrylamide, methacrylamide or Maleic acid amide and isocyanates such as. B. vinyl isocyanate or allyl isocyanate. Of the Crosslinking comonomers mentioned above are N-methylolacrylamide and N-methylol methacrylamide preferred, primarily because Copolymer chains containing one of these monomers under the action of elevated temperatures for condensation with each other and thus for the formation of desired intermolecular networks are capable. The possibly desired solvent resistance of the preferred acrylate coating can but also by the presence of a foreign crosslinking agent such. B. one Melamine or urea-formaldehyde condensation product can be achieved. Becomes no solvent resistance required, so crosslinking agents can be dispensed with become.  

The preferred acrylate coating can be applied to the film on one or both sides. However, it is also possible to provide only one side of the film with the coating according to the invention and to apply another coating to the opposite side. The coating formulation can contain known additives such as. B. antistatic agents, wetting agents, surfactants, pH regulators, antioxidants, dyes, pigments, anti-blocking agents such as. B. colloidal SiO ₂ etc. Usually it is appropriate to incorporate a surfactant to increase the ability of the aqueous coating to wet the polyester carrier film.

In a further preferred embodiment of the invention, a water-soluble or hydrophilic coating is used to achieve better adhesion with hydrophilic layers or printing inks. The preferred hydrophilic coating can be achieved in three ways:

• 1. A blend of an aromatic copolyester (I-1) with one in water dispersible functional group and a polyvinyl alcohol (II-1),
• 2. A blend of an aromatic copolyester (I-2) with one in water dispersible functional group and a polyglycerol polyglycidyl ether (II-2), or
• 3. A mixture of an aqueous polyurethane (I-3) and a Polyvinyl alcohol (II-3).

The aromatic copolyesters (I-1 and I-2) are made from aromatic dicarboxylic acids, such as, for example, terephthalic acid, 2,6-naphthalenedicarboxylic acid or isophthalic acid, optionally branched or condensed aliphatic diols such as. B. Ethylene glycol, diethylene glycol, 2-methylpropanol or 2,2-dimethylpropanol and one ester-forming compound which carries a water-dispersible functional group. Examples of the functional groups are: hydroxyl, carboxyl, sulfonic or phosphoric acid groups or their salts. Sulfonic acid and Carboxylic acid salts. As a polyvinyl alcohol component (II-1 and II-3) anyone can Polyvinyl alcohol can be used which is water soluble and with normal  Polymerization techniques can be produced. Generally such polyvinyl alcohols produced by the saponification of polyvinyl acetates. The degree of saponification should preferably at least 70%, but more preferably 80-99.9%. As Polyglycerol polyglycidyl ether (II-2) are reaction products of glycerin and Epichlorohydrin with molecular weights between approximately 250 and 1200 are used. The aqueous polyurethane (I-3) is made from a polyol, such as polyester Glycol end groups, polyoxyethylene glycol, polyoxypropylene glycol, Polyoxytetramethylene glycol or acrylic polyols, and a diisocyanate, such as Example xylene diisocyanate, hexamethylene diisocyanate, 4,4'-dicycloheylmethane diisocyanate, toluidine diisocyanate, phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate and 1,5-naphthalene diisocyanate.

The preferred copolyester, acrylate and hydrophilic coatings may also contain other known additives such as. B. antistatic agents, wetting agents, surfactants, pH regulators, antioxidants, dyes, pigments, anti-blocking agents, such as. B. colloidal SiO ₂ , etc.

The total thickness of the film can vary within wide limits and depends according to the intended use. The preferred embodiments of the films according to the invention have total thicknesses of 4 to 400 μm, 8 to 300 μm, in particular 10 to 300 μm, are particularly preferred. The thickness of the, if applicable existing intermediate layers is generally independent in each case 0.5 to 15 µm from each other, with intermediate layer thicknesses of 1 to 10 µm, in particular 1 to 8 μm, are preferred. The values given refer to each on an intermediate layer. The thickness of the cover layers is independent of selected the other layers and is preferably in the range from 0.1 to 10 μm, in particular 0.2 to 5 microns, preferably 0.3 to 2 microns, with applied on both sides Cover layers with respect to thickness and composition may be the same or different can. The thickness of the base layer results from the difference of Total thickness of the film and the thickness of the top and intermediate layers applied  and can therefore vary within wide limits analogously to the total thickness.

The invention further relates to a method for producing the invention Polyester film according to the known extrusion or coextrusion process.

It is useful to add the flame retardant to the film using the masterbatch process incorporate. One masterbatch with the flame retardant is used with the others Components mixed in the extruder.

In the course of this procedure, it is carried out in such a way that that of the single-layer Foil / the melt corresponding to the individual layers of the foil Melt is extruded / co-extruded through a flat die, the resultant The film is pulled off for solidification on one or more rollers then biaxially stretched (oriented), the biaxially stretched film is heat-set and if necessary in the course of the manufacturing process on the intended for treatment Surface layer is corona or flame treated and / or possibly in the course of Manufacturing process or offline functionally coated.

Biaxial stretching is generally carried out sequentially. Doing so preferably only in the longitudinal direction (i.e. in the machine direction, = MD direction) and then in the transverse direction (i.e. perpendicular to the machine direction, = TD direction) stretched. This leads to an orientation of the molecular chains. Stretching in The longitudinal direction is preferably carried out with the help of two in accordance with the desired Stretch ratio of rolls running at different speeds. Used for cross stretching generally a corresponding tenter frame.

A simultaneous, i.e. H. simultaneous stretching of the film according to the invention in both Directions (MD direction and TD direction) with the help of a suitable one Clip frame has not proven to be useful. That is, this stretch leads to a film that has too little whiteness and too little opacity.  

The temperature at which the drawing is carried out can be in a relative vary widely and depends on the desired properties of the Foil. In general, the longitudinal stretching at 80 to 130 ° C and the Lateral stretching is carried out at 90 to 150 ° C. The longitudinal stretch ratio is generally in the range from 2.5: 1 to 6: 1, preferably from 3: 1 to 5.5: 1 Cross-stretch ratio is generally in the range from 3.0: 1 to 5.0: 1, preferably from 3.5: 1 up to 4.5: 1.

In the subsequent heat setting, the film is held at about 0.1 to 10 s Temperature kept from about 150 to 250 ° C. Then the film is in the usual Way wrapped up.

The coatings according to the invention which may be present can be according to the on the Known coating methods used in the field of film production oriented opaque, flame-retardant polyester film can be applied. The Coating z. B. by roller coating, spray coating, Slot casting application or dip coating. Is preferred the opaque Polyester film coated with engraving rollers. Before coating, the Foil surface preferably a corona treatment in one Corona unloader such. See, for example, US-A-3,520,959, US-A-3,820,939 and US-AA 028 032. Corona treatment reduces hydrophobicity the thermoplastic film surface, whereby the aqueous coating Can wet the surface better. This will increase the adhesion of the coating to the Improved film surface.

The coating can be applied in-line to the film at any stage thermoplastic film are applied, in the stage before stretching at the time between the casting of the amorphous film and the first stretching, how it z. B. is described in GB-B-1 411 564, or in the stage between the Stretching processes, d. H. after uniaxial stretching, but before biaxial  Stretch as it is e.g. B. is described in US-A-4,214,035. The film during the Stretching or the final conditioning stages supplied heat is sufficient normally out to the water and / or other volatile components from the Distribute coating and dry it. The coating can also after the stretching processes (offline) on the finished biaxially oriented film become. In most cases, such an order procedure is a separate one Drying step required.

A particular advantage of the film according to the invention is expressed by a good one Adhesion to other materials and characterized by a high opacity. surprisingly The gloss of the film was also very high. The opacity of the film according to the invention is more than 55%, preferably more than 60% and particularly preferably more than 65%. The gloss of the film according to the invention is more than 50, preferably more than 70 and particularly preferably more than 90.

Another advantage of the invention is that this is in the manufacture of the film Regenerate accumulating in a concentration of 10 to 70 wt .-%, based on the total weight of the film, can be reused without the physical properties of the film are significantly affected. In particular, the regenerate (essentially made of polyester raw material and Cycloolefin copolymers (COC) consisting of the film is not undefined in color changed what is the case with the films according to the prior art.

In addition, another advantage of the invention is that the Manufacturing costs of the film according to the invention are comparable to conventional ones non-transparent films according to the prior art. The other processing and properties relevant to use of the film according to the invention remain in the Essentially unchanged or even improved.

It was also surprising that using masterbatch technology, one  suitable predrying and / or pre-crystallization and, if appropriate, use of small amounts of a hydrolysis stabilizer with the flame retardant film required profile of properties economically and without gluing in the dryer can be produced and that the film does not become brittle after exposure to temperature and when Buckling does not break.

It was very surprising that with this excellent result and the required flame protection

• - The yellowness index of the film compared to a film that has not been finished The measurement accuracy is not negatively influenced;
• - no outgassing, no nozzle deposits, no frame evaporation occur, which gives the film an excellent appearance and a has an excellent profile and flatness;
• - The flame retardant film has excellent stretchability distinguished, so that they are reliable and stable High-speed film lines up to speeds of 420 m / min can be produced reliably.

This means that a film is also economically viable.

The film is very suitable for interior paneling, trade fair construction and Trade fair articles, for protective coverings of machines and vehicles and others Shaped body as well as a printable cover for advertising signs outdoors and also in exhibition stand construction and furniture decor, where fire protection is important. In addition, it is also excellent for use in the industrial sector, e.g. B. at the Production of stamping foils and suitable as a label foil. Next to it is the film of course suitable for imaging papers, printing sheets, just a few possible To name applications. In these applications there is good adhesion to printing inks, Metal layers and other coatings advantageous.  

The processing and winding behavior of the film, especially on high-speed machines (winders, metallizers, printing and laminating machines) very good. The coefficient of friction is a measure of the processing behavior the film that is less than 0.6. The winding behavior is next to a good one Thickness profile, excellent flatness and low coefficient of friction decisively influenced by the roughness of the film. It has been found that the winding of the film according to the invention is particularly good when under Retaining the other properties mean roughness in a range from 50 to 250 nm. The roughness can a. by varying the COC concentration and the process parameters in the manufacturing process in the specified range vary.

The table below (Table 1) summarizes the most important film properties according to the invention.

The following measured values were used to characterize the raw materials and the foils used:

surface defects

The surface defects are determined visually.

SV (standard viscosity)

The standard viscosity SV (DCE) is measured based on DIN 53 726 in dichloroacetic acid.
The intrinsic viscosity (IV) is calculated from the standard viscosity as follows

IV (DCE) = 6.67.10 ^-4 SV (DCE) + 0.118

friction

The friction was determined according to DIN 53 375. The sliding friction number was 14 days measured after production.

Black marker test

This test is used to check the coating quality of with acrylate coated foils. With the pen (brand: Black Ink Marker - Sanford EXPO Dry Erase Marker) is a line of color on the coated film side entire sample width applied. This line of paint has to dry for 2 minutes, afterwards it is removed from the coated side of the film with facial tissue abraded. After rubbing off the paint line, there must still be a slight color residue being visible. The color line must not be completely rubbed off. Remains a such a color residue, the assessment is good, otherwise the assessment is bad.

roughness

The roughness R _{a of} the film was determined according to DIN 4768 with a cut-off of 0.25 mm.

Whiteness and opacity

The degree of whiteness and the opacity are determined using the electrical "®ELREPHO" remission photometer from Zeiss, Oberkochem (DE), standard illuminant C, 2 ° normal observer. The opacity is determined in accordance with DIN 53 146. The whiteness is defined as WG = RY + 3RZ - 3RX. WG = whiteness, RY, RZ, RX = corresponding reflection factors when using the Y, Z and X color measurement filter. As White standard, a barium sulfate compact (DIN 5033, part 9) is used. A detailed description is e.g. B. in Hansl Loos "color measurement", Verlag Profession and Schule, Itzehoe (1989).

Light transmission

The light transmittance is measured based on ASTM-D 1033-77.

shine

The gloss was determined in accordance with DIN 67 530. The reflector value was measured as optical parameter for the surface of a film. Based on the standards ASTM-D 523-78 and ISO 2813 the angle of incidence was set at 60 °. A beam of light hits at the set angle of incidence on the flat test surface and is from this reflected or scattered. Those striking the photoelectronic receiver Light rays are displayed as a proportional electrical quantity. The reading is dimensionless and must be specified with the angle of incidence.

Glass transition temperature

The glass transition temperature Tg of the COCs was determined using foil samples the DSC (Differential Scanning Calorimetry) determines (DIN 73 765). Was used the device DSC "Pyris" from Perkin-Elmer. The heating rate was 20 K / min and the initial weight approx. 12 mg. In the first heating process, the glass transition  Tg determined. The samples often showed enthalpy relaxation (a peak) at the beginning of the stepped glass transition. The temperature at which the gradual change in heat capacity - regardless of the peak-shaped enthalpy relaxation - reached half its height in the first heating process. In all cases, only a single glass transition stage was included in the thermogram first heating observed.

Contact angle with water

The polarity of the surface was determined by a contact angle measurement at 23 ° C and a relative humidity of 50% of distilled water. By means of a Dosing syringe is a 1 to 2 mm wide drop of distilled water on the Foil surface applied. Because the measurement is due to lighting (Evaporation), charging or spreading behavior is time-dependent, the needle remains in the drop so that the drop magnifies and carefully during the measurement then the contact angle is immediately read using a goniometer eyepiece. (Measurement of the advancing angle). The mean value is formed from 5 measurements.

The following examples serve to explain the invention in more detail:

example 1

Polyethylene terephthalate chips (made by the transesterification process with Mn as transesterification catalyst, Mn concentration: 100 ppm) were at 150 ° C on a Residual moisture dried below 100 ppm and the extruder for the base layer B fed. In addition, chips made from cycloolefin copolymers (COC) from Ticona: ®Topas 6015 (COC consisting of 2-norbomene and ethylene, see also W. Hatke: Films made of COC, Kunststoffe 87 (1997) 1, pp. 58-62) with a Glass transition temperature Tg of about 160 ° C also the extruder for the Base layer B fed. The proportion of the cycloolefin copolymer (COC) in the Base layer was 10% by weight.  

The flame retardant is the organic soluble in PET Phosphorus compound ®Amgard P1045 from Albright & Wilson.

The flame retardant is added in the form of a masterbatch. The masterbatch is composed of 10% by weight of flame retardant and 90% by weight of PET and has a bulk density of 750 kg / m ³ .

It was made by extrusion, gradual orientation in the longitudinal and transverse directions, Fixation and subsequent corona treatment (8 kW / m) a white, opaque single-layer film with a total thickness of 23 microns.

Base layer B, mixture of:
88.0% by weight polyethylene terephthalate homopolymer with an SV value of 800
10.0% by weight of cycloolefin copolymers (COC) from Ticona, Topas 6015
2.0% by weight of flame retardant

The manufacturing conditions in the individual process steps were:
extrusion:
Base layer temperatures: t 280 ° C
Take-off roller temperature: 30 ° C
Longitudinal stretching:
Temperature: 80-125 ° C
Longitudinal stretch ratio: 4.2
Transverse stretching:
Temperature: 80-135 ° C
Lateral stretch ratio: 4.0
fixation:
Temperature: 230 ° C
Duration: 3 s

The film had the required good properties, the required flame protection and shows the desired handling and processing behavior. The Properties achieved in films produced in this way are shown in Table 2  summarized.

Example 2

The film was produced as in Example 1, but without corona treatment after biaxial stretches. A latex with a solids content of 4.5% by weight, consisting of a Copolymers of 60% by weight methyl methacrylate, 35% by weight ethyl acrylate and 5% by weight N-methylolacrylamide and a surfactant was applied as an adhesion promoter coating Polyester film applied:

The elongated film was corona treated (2 kW / m) and then through Reverse gravure coating coated with the latex described above.

The biaxially stretched film was heat set at 230 ° C. The dry weight of the coating was approximately 0.035 g / m ² with a coating thickness of approximately 0.0025 µm.

The film was checked for its reprographic adhesion and showed good adhesion.

Example 3

The film was produced as in Example 1, but without corona treatment after the biaxial stretching. An aqueous dispersion with 6 wt% copolyester consisting of 95 mol% isophthalate, 5 mol% Na-5-sulfoisophthalate and 100 mol% ethylene glycol, and 0.56 wt% colloidal SiO ₂ was coated as follows applied to a polyester film:

The elongated film was reverse-coated with the above described copolyester dispersion coated.

The biaxially stretched film was heat set at 230 ° C. The dry weight of the coating was approximately 0.030 g / m ² with a coating thickness of approximately 0.0025.

Two samples of the film coated in this way on one side were placed in a vacuum laboratory coater, in such a way that in one sample the coated side and in the other the uncoated side was metallized. The vacuum chamber was evacuated to below 10 ^-4 torr and about 500 Å of aluminum was evaporated from a tungsten filament on both the uncoated side and the coated sample.

Each sample was opened within 30 seconds after removal from the vacuum chamber "Metal abrasion" checked. For this purpose, a test was carried out on each sample examined Cotton fleece with the same number of strokes and approximately the same print lightly rubbed over the metal surface. The "abrasion behavior" of the coated Side of the film was rated as good, which means good adhesion.

Example 4

The film was produced as in Example 1; however without corona treatment after biaxial stretching. An aqueous dispersion with a solids content of 7% by weight, consisting of 50% by weight of the aromatic copolyester A1 (copolyester containing 90 mol% terephthalate, 10 mol% 5-sodium sulfoisophthalate, 80 mol% ethylene glycol and 20 mol% diethylene glycol) , 45% by weight of the water-dispersible polymer B2 (polyvinyl alcohol with a degree of saponification of 88 mol% and a degree of polymerization of 1,700) and 5% by weight of inert particles D1 (colloidal SiO ₂ with a particle diameter of 0.05 μm) applied as a coating to a polyester film as follows:

The elongated film was coated with the copolyester dispersion described above by reverse gravure coating. The dry weight of the coating was approximately 0.040 g / m ² with a coating thickness of approximately 0.05 µm.

An aqueous polyvinyl acetal solution was used to assess the adhesion promoter effect (S-Lec KX-1 manufactured by Sekisui Chemical Co., Ltd .; hereinafter referred to as KX-1  referred to) applied to the coated film and dried. The Coating solution had a concentration of 8 wt .-% and was with a Baker-type applicator applied with a layer thickness of 127 µm. The Coated film was immediately dried in a drying at 100 ° C for 4 minutes Oven put. A black square (area: 12 × 12 cm) was covered with an ink jet Printer (BJC-600 J, Canon Inc.) on the surface of the dried KX-1 Coating printed and for 12 hours at 23 ° C and 50% relative humidity dried in air. An adhesive tape (cello tape, Nichiban Inc. width: 18 mm) was made glued to the printed surface and quickly peeled off. The degree of with that Adhesive tape separated printed surface was determined visually. The coated film showed good adhesive properties.

Comparative Example 1

A film as in Example 1 was produced, but without corona treatment. The contact angle to water was 65.5 ° and the adhesion to metal was poor.

Claims (26)

1. Opaque, flame-retardant, biaxially oriented polyester film comprising at least one layer, characterized in that it contains at least one flame retardant and at least this. Layer contains a cycloolefin copolymer (COC) in a concentration of 2 to 60 wt .-%, based on this layer, wherein the glass transition temperature of the cycloolefin copolymer (COC) is in the range of 70 to 270 ° C and that at least one surface of the film is adhesion-promoted , 2. Polyester film according to claim 1, characterized in that the Cycloolefin copolymer (COC) polynorbornene, polydimethyloctahydronaphthalene, Contains polycyclopentene or poly (5-methyl) norbornene. 3. Polyester film according to claim 1 or 2, characterized in that the Cycloolefin copolymers (COC) have a glass transition temperature in the range of 90 up to 250 ° C. 4. Polyester film according to one of claims 1 or 2, characterized in that the cycloolefin copolymer (COC) has a glass transition temperature in the Has range of 110 to 220 ° C. 5. Polyester film according to one or more of claims 1 to 4, characterized characterized in that the film has an opacity of more than 55%. 6. Polyester film according to one or more of claims 1 to, characterized characterized in that the film has a whiteness of more than 70%.   7. Polyester film according to one or more of claims 1 to 6, characterized characterized in that the film has a gloss of more than 5. 8. Polyester film according to one or more of claims 1 to 7, characterized characterized in that the layer 0.5 to 25 wt .-% further contains vacuole-initiating and / or white fillers and / or pigment, each based on the weight of the layer. 9. Film according to one or more of claims 1-8, characterized in that the flame retardant is selected from one or more organic phosphorus compounds, preferably dimethyl methyl phosphonate. 10. Film according to one or more of claims 1 to 9, characterized characterized in that the film contains 0.5 to 30.0 wt .-% flame retardant. 11. Polyester film according to one or more of claims 1 to 10, characterized characterized that treated surface of the film treated with corona has been. 12. Polyester film according to one or more of claims 1 to 11, characterized characterized in that at least one surface of the film is a Adhesion promoter layer carries. 13. Polyester film according to claim 12, characterized in that the Adhesion layer contains a copolyester. 14. Polyester film according to claim 12, characterized in that the Adhesion layer is an acrylate coating.   15. Polyester film according to claim 12, characterized in that the Adhesion layer is a hydrophilic coating. 16. Film according to one or more of claims 1 to 15, characterized characterized that the film contains recycled material. 17. Film according to one or more of claims 1 to 8, characterized characterized that it has a single-layer structure. 18. Film according to one or more of claims 1 to 10, characterized characterized in that the film has a multilayer structure with at least. has a cover layer and at least one base layer. 19. Film according to claim 18, characterized in that the multilayer Structure two cover layers and one between the cover layers Has base layer. 20. Polyester film according to claim 18 or 19, characterized in that an intermediate layer between the COC-containing layer and the cover layer is arranged. 21. Film according to one of claims 18 to 19, characterized in that at least one flame retardant is contained in the base layer. 22. Polyester film according to one or more of claims 1 to 21, characterized characterized that the bonded side has a contact angle to water of ≦ 64 °. 23. Film according to one or more of claims 1-22, characterized in that  that the film has an opacity of more than 60% and that the adhesion-promoting surface has a contact angle to water of ≦ 64 °. 24. A method for producing a film according to claim 1, characterized characterized that that of the single-layer film / that of the individual layers the melt corresponding to the film / corresponding melts by a Flat die is extruded / co-extruded, the film thus obtained for Solidification is peeled off on one or more roller (s), the film then biaxially stretched (oriented), the biaxially stretched film heat-set and optionally between extrusion and heat-setting coated and / or after heat setting on the treatment provided surface layer is corona or flame treated. 25. Use of a film according to claim 1 as interior lining, Protective cover, packaging film, embossing film and label film. 26. Use of a film according to claim 1 in laminates, Imaging papers, printing sheets, furniture decorations and magnetic Acquisition boards.