DE10043785A1 - Mat multilayer film comprises base layer comprising a crystallizable bibenzoate-modified thermoplastic polymer, and at least one covering layer comprises a blend of two components - Google Patents

Abstract

A multilayer film comprises: (a) a base layer comprising a crystallizable bibenzoate-modified thermoplastic polymer (I) as the major component; and (b) at least one covering layer comprising a blend of two components (II) and (III). An Independent claim is also included for a process for producing the film, comprising: (i) coextruding the corresponding starting materials through a slit die; (ii) biaxially stretching and thermofixing the resulting film; and (iii) optionally coating the film on one or both sides.

Description

The invention relates to a biaxially oriented film which has a base layer which contains at least 50% by weight of a bibenzene-modified thermoplastic, and has at least one matt cover layer, which is a mixture or a blend contains two components I and II. The invention further relates to a method for the production of the film and its use.

Component I of the mixture or blend is preferably a Polyethylene terephthalate homopolymer or polyethylene terephthalate copolymer and / or a mixture of polyethylene terephthalate homo- or copolymers.

Component II of the mixture or blend is preferably a Polyethylene terephthalate copolymer, which preferably from the condensation product of the following monomers or their derivatives capable of forming polyesters consists of: isophthalic acid, aliphatic dicarboxylic acid, sulfomonomers, the one Metal sulfonate group on the aromatic part of an aromatic dicarboxylic acid and aliphatic or cycloaliphatic glycol.

The top layer according to the invention is characterized by a characteristic matt Surface or optics and is particularly suitable for use as Packaging film or well suited for applications in the industrial sector where in particular UV protection or non-permeability of the UV light is required becomes.

The packaging industry has a high need for transparent, high-gloss Plastic films, such as B. biaxially oriented polypropylene or biaxially oriented Polyester films. In addition, there is an increasing need for such foils, where there is protection against ultraviolet radiation and at least where  a surface layer is not high-gloss, but stands out through distinguishes characteristic matt appearance and thereby z. B. the Packaging a particularly attractive and therefore effective advertising appearance at the same time provides protection against UV radiation.

No. 4,399,179 describes a coextruded biaxially oriented polyester film described, which consist of a transparent base layer and at least one matt Layer consists essentially of a certain Polyethylene terephthalate copolymer exists and also inert particles with a Contains diameter from 0.3 to 20 microns in a concentration of 3 to 40 wt .-%. The special copolymer is a processing aid through which the viscosity of the melt containing inert particles is reduced, so that a flawless Extrusion of this layer is possible. The mattness of the film is increased by adding the inert particles reached in the corresponding layer.

EP 0144 978 describes a self-supporting oriented film made of thermoplastic Described plastic, which one on at least one of its two surfaces continuous polyester coating that acts as an aqueous dispersion on the film is applied before the last stretching step. The polyester coating consists of a condensation product of various monomers that are used to form Are capable of polyesters, such as isophthalic acid, aliphatic dicarboxylic acids, Sulfomonomers and aliphatic or cycloaliphatic glycols.

EP-A 0 620 245 describes films made of polyethylene terephthalate, which are improved in terms of their thermal stability. These slides included Antioxidants which are suitable for trapping radicals formed in the film and break down formed peroxide. A proposal on how the UV stability of such films there is no need to improve this document.

DE 198 23 991 describes amorphous plates which contain a bibenzene-modified polyalkylene terephthalate and / or a bibenzene-modified polyalkylene naphthalate as the main constituent. These plates are 0.1 to 20 mm thick, amorphous, ie not crystalline, undrawn and unoriented. The plates are particularly characterized by good mechanical properties in a wide temperature range. Good mechanical properties are understood to mean that no fracture occurs when measuring the impact strength a _n according to Charpy (ISO 179 / 1D) and that the Izod impact strength according to ISO 180 at -40 ° C. is preferably in the range from 10 to 140 kJ / m ² lies. The amorphous plates described are produced using smoothing calender technology and by freezing below the glass transition temperature by means of cooling and smoothing.

In the cases described there is no evidence of how a film at least on a film surface a low gloss with a still high Transparency can be imparted to the film and, like such a film, a high one UV stability could be conferred.

The object of the present invention was therefore to provide a film with at least one to provide a matt surface that is simple and economical can produce the good physical properties of the known films owns, does not cause disposal problems and is particularly affected by the Absorption of UV light and characterized by high inherent UV stability.

A high inherent UV stability means that the films are exposed to sunlight or other UV radiation are not or only extremely little damaged, so that the Films are suitable for outdoor applications and / or critical indoor applications. In particular, the foils should not turn yellow when used outdoors for several years, show no embrittlement or cracking on the surface and neither Have deterioration in mechanical properties. High UV stability means that the film absorbs UV light and light only in the visible Area lets through.  

The good mechanical properties preferably include a high modulus of elasticity (E _MD <3200 N / mm ² ; E _TD <3500 N / mm ² ) and good tensile strength values (in MD <100 N / mm ² ; in TD <130 N / mm ² ).

Good stretchability includes e.g. B. that the film in its manufacture excellent in both longitudinal (MD) and transverse (TD) directions and without breaks can orient.

The task is solved by a coextruded and biaxially oriented film Art.

Component I of the mixture or blend is preferably a Polyethylene terephthalate homopolymer or polyethylene terephthalate copolymer or a mixture of polyethylene terephthalate homo- and / or copolymers.

Component II of the copolymer or of the mixture or of the blend is preferably a polymer containing at least one sulfonate group, in particular a condensation product of the following monomers or their derivatives capable of forming polyesters:

• A) 65 to 95 mol% isophthalic acid;
• B) 0 to 30 mol% of at least one aliphatic dicarboxylic acid with the formula HOOC (CH ₂ ) _n COOH
  where n ranges from 1 to 11;
• C) 5 to 15 mol% of at least one sulfomonomer containing an alkali metal sulfonate group on the aromatic part of a dicarboxylic acid;
• D) the stoichiometric amount necessary to form 100 mol% condensate a copolymerizable aliphatic or cycloaliphatic glycol with 2 up to 11 carbon atoms;

where the percentages are based on the total amount of Monomers forming component II.  

Mechanical mixtures are among mixtures for the purposes of the present invention to understand which are made from the individual components. In general For this purpose, the individual components as pressed molded articles of small size, for. B. lenticular or spherical granules, poured together and with a suitable Vibrating device mechanically mixed. Another way for that Creation of the mixture consists in that the respective components I and II in Granulate form separately for the extruder for the invention Cover layer are fed and the mixture in the extruder or in the subsequent melt-carrying systems is carried out.

A blend in the sense of the present invention is an alloy-like composite of individual components I and II, which are no longer in the original components can be disassembled. A blend has properties like a homogeneous substance and can be characterized accordingly by suitable parameters.

According to the invention, the film has at least two layers. It then comprises layers a layer B (= base layer) and the matt cover layer A according to the invention. In In a further preferred embodiment of the invention, the film has three layers built up and has on one side of layer B the top layer A and on the another side of layer B on another layer C. In this case, the both layers A and C are the outer layers, which can be the same or different.

The film according to the invention contains as a main component, at least in the Base layer, a crystallizable, bibenzol-modified thermoplastic. suitable are crystallizable or partially crystalline bibenzol-modified thermoplastics for example polyesters such as bibenzene-modified polyethylene terephthalate (PETBB), Bibenzol-modified polybutylene terephthalate (PBTBB), bibenzol-modified Polyethylene naphthalate (PENBB), with bibenzene-modified polyethylene terephthalate (PETBB) is preferred.  

According to the invention, bibenzene-modified crystallizable thermoplastics are understood

• Crystallizable bibenzene-modified copolymers,
• - crystallizable bibenzol-modified compounds,
• - Crystallizable bibenzene-modified recyclate and
• - other variations of crystallizable bibenzol-modified thermoplastics.

For the production of the copolymers polyalkylene terephthalate or polyalkylene naphthalate can in addition to the main monomers such. B. Dimethyl terephthalate (DMT), bisbenzenic acid (BB), ethylene glycol (EG), propylene glycol (PG), 1,4-butanediol, Terephthalic acid (TA), and / or 2,6-naphthalene dicarboxylic acid (NDA), too Isophthalic acid (IPA), trans and / or cis-1,4-cyclohexanedimethanol (c-CHDM, t-CHDM or c / t-CHDM) can be used.

The main ingredient is that the amount of bibenzene-modified thermoplastic preferably between 50 and 99.9% by weight, particularly preferably between 75 and 99 % By weight is based on the weight of the layers equipped therewith. The the remaining amount of 100% can be conventional additives for biaxially oriented films.

Bibenzene-modified polyethylene terephthalate polymers with a crystallite melting point Tm, measured with DSC (differential scanning calorimetry) at a heating rate of 20 ° C./min. from 180 ° C to over 365 ° C, preferably from 180 ° C to 310 ° C, depending on the bibenzenic acid content, with a crystallization temperature range Tc between 75 ° C and 280 ° C, a glass transition temperature Tg between 65 ° C and 130 ° C and with a density, measured according to DIN 53479, of 1.15 to 1.40 g / cm ³ and a crystallinity between 5% and 65%, preferably 20% and 65%, are preferred starting materials for the production of the film according to the invention.

Bibenzene-modified polyethylene naphthalate polymers with a crystallite melting point Tm, measured with DSC (Differential Scanning Calorimetry) at a heating rate of 10 ° C / min. from 120 ° C to 310 ° C, preferably from 140 ° C to 280 ° C, depending on the bibenzenic acid content, with a crystallization temperature range Tc between 75 ° C and 280 ° C, a glass transition temperature Tg between 65 ° C and 120 ° C and with a density, measured according to DIN 53479, of 1.20 to 1.45 g / cm ³ and a crystallinity of between 5% and 65%, preferably 20% and 65%, are preferred starting materials for the production of the film according to the invention.

It is essential to the invention that the bibenzol-modified thermoplastic used is crystallizable. According to the invention, the bibenzenic acid content is preferably between 1 and 50 wt .-%, preferably between 5 and 45 wt .-%, in particular between 10 and 40 wt .-%, based on the weight of the bibenzol-modified thermoplastic. If the bibenzenic acid content is <50% by weight, the film according to the invention is u. U. insufficiently crystallizable after orientation. In this case, the mechanical properties deteriorate significantly.

The standard viscosity SV (DCE) of the bibenzene-modified polyethylene terephthalate, measured in dichloroacetic acid according to DIN 53728, lies between 600 and 1000, preferably between 700 and 900.

The bulk density, measured according to DIN 53466, is preferably between 0.70 kg / dm ³ and 1.0 kg / dm ³ , and particularly preferably between 0.75 kg / dm ³ and 0.90 kg / dm ³ .

The polydispersity of the bibenzene-modified polyalkylene naphthalate or bibenzene-modified polyalkylene terephthalate Mw / Mn measured by GPC preferably between 1.5 and 4.0 and particularly preferably between 2.0 and 3.5.

At least one cover layer of the multilayer film according to the invention contains an im following mixture or a blend of two components I described and II and optionally additional additives.  

Component I of the top layer mixture or of the blend preferably contains such described a thermoplastic polyester. This can also be a polyester like it was described in more detail for the base layer. For the generation of high matt degrees it has proven to be advantageous if the polyester polymer for the Component I of the cover layer according to the invention is a comparative per se has low viscosity. For the description of the viscosities of the melts a modified solvent viscosity (SV value) was used. For standard ones Polyethylene terephthalates, which are suitable for the production of biaxially oriented films, the SV values are in the range from 500 to 1200. To ensure a high level of mattness in the film To get sense of the present invention, it has proven to be beneficial if the SV value of the polymers for component I of the invention Top layer in the range from 500 to 800, preferably in the range from 500 to 750, are particularly preferably in the range from 500 to 700.

As already stated, component II of the top layer mixture is obtained by condensation of the following monomers or their derivatives capable of forming polymers:

• A) isophthalic acid,
• B) optionally an aliphatic dicarboxylic acid
• C) a sulfomonomer and
• D) the amount necessary to form 100 mol% condensate aliphatic or cycloaliphatic glycol.

The total acid equivalents present should be essentially on a molar basis correspond to the total glycol equivalents present.

Dicarboxylic acids suitable as component B) of the copolyester are e.g. B. Malon, Adipic, azelaic, glutaric, sebacic, cork, amber and brassylic acid as well Mixtures of these acids or their derivatives capable of forming polyesters. Of the acids mentioned, sebacic acid is preferred.  

Examples of sulfomonomers which have a metal sulfonate group on the aromatic part of an aromatic dicarboxylic acid (component C) are those monomers which correspond to the following general formula:

In this formula is
M is a monovalent cation of an alkali metal,
Z is a trivalent aromatic radical, and
X and Y are carboxyl groups or polyester-forming equivalents.

Monomers of this type are described in US-A 3,563,942 and 3,779,993. Examples of such monomers are sodium sulphoterephthalic acid, sodium 5-sulfoisophthalic acid, sodium sulfophthalic acid, 5- (p-sodium sulfphenoxy) isophthalic acid, 5- (sodium sulfopropoxy) isophthalic acid and the like monomers and their derivatives capable of forming polyesters, such as e.g. , B. the dimethyl ester. M is preferably Na ⁺ , Li ⁺ or K ⁺ .

The term “derivatives capable of forming polyesters” are preferred here Respondents understand with such groups that too Condensation reactions, especially transesterification reactions, to form Are capable of polyester bonds. Such groups include carboxyl groups as well whose lower alkyl esters, e.g. B. dimethyl terephthalate, diethyl terephthalate and numerous other esters, halides or salts. The acid monomers are preferred as Dimethyl ester is used because in this way the condensation reaction is better can be controlled.

Glycols suitable as component D) are e.g. B. ethylene glycol, 1,5-pentadiol, 1,6- Hexanediol, neopentylglycol, 1,10-decanediol, cyclohexane-dimethanol and the like Substances. Ethylene glycol is preferably used.  

The copolyesters can be made by known polymerization techniques. In general, the procedure is such that the acid components with glycol brought together and heated in the presence of an esterification catalyst, with subsequent addition of a polycondensation catalyst.

It has been shown that the relative proportions of components A, B, C and D, which are used to produce the mixtures according to the invention, are decisive for achieving the matt top layer. So z. B. isophthalic acid (Component A) be present at least about 65 mol% as the acid component. Component A is preferably pure isophthalic acid, in an amount of about 70 up to 95 mol% is present.

For component B it applies that any acid with the formula mentioned brings satisfactory results, with adipic acid, azelaic acid, sebacic acid, Malonic acid, succinic acid, glutaric acid and mixtures of these acids are preferred become. The amount is preferably 1 to 20 mol% when component B in the Composition is included.

The glycol component is present in a stoichiometric amount.

The copolyesters suitable for the purposes of the invention continue to stand out preferably characterized in that it has an acid number below 10, preferably from 0 to 3, an average mole weight below about 50,000 and an SV value in the range of about 300 to 700, preferably about 350 to 650.

The ratio (weight ratio) of the two components I and II The top layer mixture or blend can vary within wide limits depends on the intended use of the multilayer film. Preferably lies the ratio of components I and II in a range from I: II = 10:90 to I: II = 95: 5, preferably between I: II = 20: 80 to I: II = 95: 5 and in particular between I: I I = 30: 70 to I: II = 95: 5.  

Light, especially the ultraviolet portion of solar radiation, i.e. H. the Wavelength range from 280 to 400 nm, initiates degradation processes with thermoplastics, as a result not only the visual appearance due to color change or yellowing changes, but also the mechanical-physical properties be adversely affected.

The inhibition of these photooxidative degradation processes is of considerable technical and economic importance, since otherwise the application possibilities of numerous thermoplastics are drastically restricted.

Unmodified polyethylene terephthalates, for example, only start below Absorb 360 nm UV light, their absorption takes below 320 nm considerably and is very pronounced below 300 nm. The maximum absorption is between 280 and 300 nm.

In the presence of oxygen there are mainly chain cleavages, but none Networking observed. Carbon monoxide, carbon dioxide and carboxylic acids are the quantitatively predominant photo-oxidation products. In addition to the direct Photolysis of the ester groups still need to consider oxidation reactions that also lead to the formation of carbon dioxide via peroxide radicals to have.

The photooxidation of e.g. B. polyethylene terephthalates can also over Hydrogen elimination in the a position of the ester groups to give hydroperoxides and their Decomposition products and the associated chain cleavages (H. Day, D. M. Wiles: J. Appl. Polym. Sci 16, 1972, page 203).

UV stability can in principle be achieved by adding UV stabilizers become. UV stabilizers, d. H. UV absorbers as light stabilizers are chemical Compounds involved in the physical and chemical processes of light-induced Degradation can intervene. Soot and other pigments can partially  Effect sun protection. However, these substances are for transparent films unsuitable as they lead to discoloration or color change. For transparent films only organic and organometallic compounds that are suitable for this stabilizing thermoplastics no or only an extremely low color or Give color change.

UV stabilizers are very expensive, some of them evaporate during film production or migrate over time, so the film e.g. B. after 1 to 2 years unwanted coating shows. This increases the gloss and transparency of the film adversely affected.

In view of the fact that UV stabilizers can offer protection, the person skilled in the art would have used commercially available UV stabilizers. He would have noticed that

• - The UV stabilizer has a lack of thermal stability and at Temperatures between 200 ° C and 240 ° C decomposed or outgassed
• - Large amounts (approx. 10 to 15% by weight) of UV stabilizer are incorporated so that the UV light is absorbed and the film is not damaged.

At these high concentrations, the film is yellow-tinged after production or shows a color change. Furthermore, the mechanical properties negatively influenced. Problems arise during stretching such as e.g. B.

• - Demolition due to lack of strength, d. H. Modulus
• - Nozzle deposits, which leads to profile fluctuations
• - Roller deposits from the UV stabilizer, which affects the optical properties (cloudiness, adhesive defect, inhomogeneous surface)
• - Deposits in stretching and fixing frames that drip onto the film.

It was therefore surprising that excellent UV protection could already be achieved by using the bibenzene-modified thermoplastics according to the invention without the addition of UV stabilizers. It was also surprising that this high UV protection

• - The color of the film compared to a polyethylene terephthalate film in The accuracy of the measurement does not change, d. H. no color shift is detected;
• - no outgassing, no nozzle deposits, no frame evaporation set, which gives the film an excellent appearance and a has an excellent profile and flatness;
• - The inherently UV-stabilized film due to its excellent stretchability in Longitudinal and transverse direction, so that they are reliable and stable on so-called high speed film lines speeds of 420 m / min can be produced reliably. This is the invention Film also economically profitable.

The base layer and the top layers and any intermediate layers can also contain conventional additives such as stabilizers and antiblocking agents. You are expedient to the polymer or the polymer mixture before Melt added. As stabilizers, for example Phosphorus compounds, such as phosphoric acid or phosphoric acid esters, are used. Typical antiblocking agents (also referred to as pigments in this context) are inorganic and / or organic particles, for example calcium carbonate, amorphous silica, 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 set dicarboxylic acids, carbon black, titanium dioxide, kaolin or cross-linked 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 individual layers in the usual concentrations, e.g. B. as a glycolic dispersion  added during polycondensation or via masterbatches during extrusion become. Pigment concentrations of 0.0001 to have been found to be particularly suitable 10 wt .-% proven, based on the weight of the layers equipped with it. By adding these particles z. B. in the top layer A according to the invention another advantageous way to vary the degree of matting of the film. With the An increase in pigment concentration is usually an increase in Matt degrees of the film connected. A detailed description of the antiblocking agents can be found, for example, in EP-A 0 602 964.

The present invention also relates to a method for producing the film according to the invention. It includes that

• a) Production of a film from base and top layers and any existing Intermediate layers by coextrusion,
• b) biaxial stretching of the film and
• c) heat setting of the stretched film.

To produce the matt top layer according to the invention are useful Granules from mixture component I and granules from Mixing component II in the desired mixing ratio directly to the extruder fed. It has proven useful for the extrusion of the to use a matte top layer according to the invention a twin-screw extruder, how he z. B. is described in EP-A 0 826 478. The two materials can be melt at about 300 ° C and with a residence time of about 5 min and extrude. Under these conditions, transesterification reactions can take place in the extruder expire in which further copolymers of the homopolymers and Can form copolymers.

The polymers for the base layer are fed via a further extruder. Approximately Existing foreign bodies or impurities can be removed from the polymer melt Filter off before extrusion. The melts are then in a multi-layer die formed into flat melt films and layered on top of each other. Subsequently  the multilayer film with the help of a cooling roller and optionally other rollers peeled and solidified.

Biaxial stretching is generally carried out sequentially or simultaneously. With sequential stretching, it is preferably only in the longitudinal direction (i.e. in Machine direction) and then in the transverse direction (i.e. perpendicular to Machine direction). This leads to an orientation of the molecular chains. The Stretching in the longitudinal direction can be done with the help of two according to the desired one Carry out stretching ratio of rolls running at different speeds. To the cross stretching generally uses a corresponding tenter frame. In the The film is simultaneously stretched simultaneously in the longitudinal and transverse directions in one Tenter frame stretched.

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 about 80 to 135 ° C and the Cross stretching is carried out at approx. 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. If desired, another can be added to the transverse stretch Connect longitudinal stretching and even a further transverse stretching.

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 film can also be coated on at least one of its surfaces, so that the coating on the finished film has a thickness of preferably 5 to 100 nm, in particular 20 to 70 nm, in particular 30 to 50 nm. The coating is preferably applied in-line, i. H. during the film manufacturing process, expediently before transverse stretching. The application is particularly preferred  by means of the so-called "reverse gravure-roll coating" process, in which the Let the coatings be applied extremely homogeneously in the layer thicknesses mentioned. The coatings are preferred as solutions, suspensions or dispersions applied, particularly preferably as an aqueous solution, suspension or dispersion. The coatings mentioned give the film surface an additional one Function z. B. the film becomes sealable, printable, metallizable, sterilizable, antistatic, or improve z. B. the aroma barrier or enable liability for materials that would otherwise not adhere to the film surface (e.g. photographic emulsions). Examples of substances / compositions that a Additional functionality are:

Acrylates such as z. B. are described in WO 94/13476, ethyl vinyl alcohols, PVDC, water glass (Na ₂ SiO ₄ ), hydrophilic polyesters (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, vinyl acetates as described, for example, in WO 94/13481, polyvinyl acetates, polyurethanes, alkali metal or alkaline earth metal 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 both film surfaces are applied, 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 those previously mentioned desired layer thicknesses.

Furthermore, the films can be coated, preferably in an off-line process, with metals such as aluminum or ceramic materials such as SiO _x or Al _x O _y . This improves their gas barrier properties in particular.

The film according to the invention preferably also has a second cover layer C. The structure, thickness and composition of this second cover layer can be independent be selected from the existing top layer, the second Top layer also the polymers or polymer mixtures already mentioned for the Base layer or the matt cover layer according to the invention can contain, but not must be identical to those of the first cover layer. The second top layer can also contain other common top layer polymers.

There may be any between the base layer and the cover layers or several intermediate layers. You can e.g. B. from for Polymers described base layer exist. In a particularly preferred Embodiment they consist of the polymer used for the base layer. They can also contain the usual additives described. The thickness of the Interlayer is generally larger than 0.3 microns and is preferably in Range from 0.5 to 15 µm, especially 1.0 to 10 µm.

The thickness of the cover layers is generally greater than 0.1 μm and lies preferably in the range from 0.2 to 5 μm, in particular 0.2 to 4 μm, the Cover layers can be of the same or different thickness.

The total thickness of the film according to the invention can vary within wide limits and depends on the intended use. It is preferably 4 to 500 µm, in particular 5 to 450 µm, preferably 6 to 300 µm, wherein the base layer is preferably about 40 to 90% of the Total thickness.

Weathering tests have shown that the matt films according to the invention themselves after 5 to 7 years (extrapolated from weathering tests) outdoor use in generally no increased yellowing, no embrittlement, no cracking on the Surface and have no deterioration in mechanical properties.  

Another advantage is that the manufacturing cost of the invention Film is only slightly above that of a film made of standard polyester raw materials. The other processing and use properties of the The film according to the invention remains or remains essentially unchanged even improved. In addition, the manufacture of the film ensures that this Regenerate in a proportion of up to 50% by weight, preferably 10 to 50% by weight, in each case based on the total weight of the film, can be reused without the physical properties of the film are negatively affected become.

The film is therefore ideal for packaging light and / or air sensitive food and beverages.

In summary, the film according to the invention is characterized by a UV light Impermeability, high inherent UV stability, low gloss, in particular a low gloss of the matt film surface A, and by a comparatively low turbidity. It also has a good winding and Processing performance. It is also worth mentioning that the invention The top layer can be easily written on with a ballpoint pen, felt-tip pen or fountain pen.

The gloss of the film surface A is preferably less than 70. In a preferred one Embodiment, the gloss of this side is less than 60 and in one particular preferred embodiment less than 50. This film surface thus has a particularly attractive character and is therefore particularly suitable as an external one Packaging surface.

The haze of the film is preferably less than 40%. In a preferred one In one embodiment, the haze of the film is less than 35% and in one particularly preferred embodiment less than 30%. By comparative low cloudiness of the film, the film can e.g. B. can be printed in reverse printing or it  Viewing windows can be installed through which z. B. to recognize the contents very well is.

Due to the surprising combination of excellent properties, the film according to the invention excellent for a large number of different applications, for example for interior cladding, for exhibition stand construction and exhibition items, as Displays, for signs, for protective glazing of machines and vehicles, in Lighting sector, in shop and shelf construction, for promotional items, as a lamination medium, for greenhouses, roofing, external cladding, covers, Applications in the construction sector and illuminated advertising profiles, shadow mats, Electrical applications and a variety of other moldings.

Further areas of application are the use for the production of labels (Labels), as a release film for the production of GRP semi-finished products, as an embossing film or in- Mold-Labeling.

The table below (Table 1) summarizes the most important of the invention Film properties together again.  

Table 1

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

measurement methods

DIN = German Institute for Standardization
ISO = International Organization for Standardization
ASTM = American Society for Testing and Materials

surface gloss

The surface gloss is measured at a measuring angle of 60 ° according to DIN 67530.

Mechanical properties

The modulus of elasticity and tensile strength and elongation at break are in longitudinal and Transverse direction measured according to ISO 527-1-2.  

Weathering (both sides), UV stability

The UV stability is tested according to the test specification ISO 4892 as follows:
Test device: Atlas Ci 65 Weather Ometer
Test conditions: ISO 4892, ie artificial weathering
Irradiation time: 1000 hours (per side)
Irradiation: 0.5 W / m ² , 340 nm
Temperature: 63 ° C
Relative humidity 50%
Xenon lamp: inner and outer filter made of borosilicate
Irradiation cycles: 102 minutes of UV light, then 18 minutes of UV light with water spraying the samples, then again 102 minutes of UV light, etc.

yellowness

The yellowness index (YID) is the deviation from the colorlessness in the direction of "yellow" and is measured according to DIN 6167. Yellowness indexes (YID) of <5 are not visually visible.

SV (DCE), IV (DCE)

The standard viscosity SV (DCE) is based on DIN 53726 in dichloroacetic acid measured.

The intrinsic viscosity (IV) is calculated as follows from the standard viscosity (SV) IV (DCE) = 6.67.10 ^-4 SV (DCE) + 0.118

cloudiness

Haze is the percentage of light that passes through the radiated light beam deviates by more than 2.5 ° on average. The sharpness will determined at an angle of less than 2.5 °.

The turbidity is measured using the "HAZEGARD plus" measuring device in accordance with ASTM D 1003.  

The following examples and comparative examples are each Films made on an extrusion line.

All foils were processed on both sides per 1000 hours per the test specification ISO 4892 Weathered side with the Atlas Ci 65 Weather Ometer from Atlas and then with regard to the mechanical properties, the yellowness index (YID), the Surface defects, light transmission and gloss checked.

The following examples serve to illustrate the invention.

example 1

• A) Preparation of component II for the top layer mixture according to the invention.
  A copolyester with 90 mol% of isophthalic acid and 10 mol% of the sodium salt of 5-sulfoisophthalic acid as the acid component and 100 mol% of ethylene glycol as the glycol component was prepared by the following procedure:
  A 2 liter stainless steel reaction vessel equipped with an anchor stirrer, a thermocouple to measure the temperature of the vessel contents, an 18 inch Claisen / Vigreux distillation column with a cooler and receiver, an inlet opening and a heating jacket was preheated to 190 ° C , flushed with nitrogen and filled with 1065.6 g of dimethyl isophthalate, 180.6 g of dimethyl 5-sulfoisophthalate sodium salt and 756.9 g of ethylene glycol. A buffer (Na ₂ CO ₃ .10H ₂ O - 0.439 g) and a transesterification catalyst (Mn (OAc) ₂ 4H ₂ O - 0.563 g) were also added to the vessel. The mixture was heated with stirring while methanol was distilled off. During the distillation, the vessel temperature was gradually raised to 250 ° C. When the weight of the distillate corresponded to the theoretical yield of methanol, an ethylene glycol solution containing 0.188 g of phosphorous acid was added. The distillation column was replaced with a curved steam outlet with template. 20 g of pure ethylene carbonate were added to the reaction mixture, and violent gas evolution (CO ₂ ) started immediately. The CO ₂ development subsided after about 10 minutes. A vacuum of 240 mm Hg was then drawn and the polycondensation catalyst (0.563 g Sb ₂ O ₃ ) added in an ethylene glycol slurry. The reaction mixture was stirred for 10 minutes while maintaining the negative pressure of 240 mm Hg, after which the pressure was further reduced in steps of 10 mm Hg / min from 240 mm Hg to 20 mm Hg. As soon as the vacuum in the system was reduced to 20 mm Hg, the vessel temperature was raised from 250 ° C to 290 ° C at a rate of 2 ° C / min; raised. At a temperature of 290 ° C in the vessel, the stirrer speed was reduced and the pressure was reduced to a maximum of 0.1 mm Hg. At this point an ammeter reading of the stirrer motor was carried out. The viscosity of the polymer was controlled by letting the polycondensation proceed according to fixed values for the change in the amperage of the stirrer motor of (in each case) 2.3 A. When the desired molecular weight was reached, the vessel was pressurized with nitrogen to force the liquid polymer from the bottom plug of the vessel into a quench bath of ice water.
• B) Mixture preparation for the cover layer A according to the invention
  85% by weight of component I (polyethylene terephthalate with an SV value of 680) and 15% by weight of component II were fed to the hopper of a twin-screw extruder and the two components were extruded together at about 300 ° C. and the top layer channel A one Multi-layer nozzle supplied.
  A matte three-layer film with ABC structure and a total thickness of 12 µm was then produced by coextrusion and subsequent stepwise orientation in the longitudinal and transverse directions. The cover layers each had a thickness of 1.5 µm.

Base layer B

95% by weight bibenzene modified polyethylene terephthalate (PETBB). The PETBB has a standard viscosity SV (DCE) of 810, which corresponds to an intrinsic viscosity IV (DCE) of 0.658 dl / g. The bisbenzene acid content is 15% by weight, the glass transition temperature is 86 ° C.
5% by weight of masterbatch of 99% by weight of PETBB and 1.0% by weight of silica particles (Sylobloc® 44H from Grace, Germany) with an average particle size of 4.5 μm.

Top layer A

85% by weight of component I and
15% by weight of component II

Top layer C

90% by weight PETBB and
10% by weight of masterbatch of 99% by weight of PETBB and 1.0% by weight of silica particles (Sylobloc® 44H from Grace) with an average particle size of 4.5 μm

The individual process steps were:
longitudinal stretching
Temperature: 85-135 ° C
Longitudinal aspect ratio: 4.0: 1
transverse stretching
Temperature: 85-135 ° C
Lateral stretch ratio: 4.0: 1
Fixation temperature: 230 ° C

Example 2

Analogously to Example 1, a three-layer film with a Total thickness of 12 microns. It was just the composition of the Top layer A changed:

Top layer A

80 wt .-% component I and
20% by weight of component II

Example 3

A coextruded film with the composition according to Example 1, in which the cover layer A was composed as follows:
75% by weight of component I and
25% by weight of component II

Example 4

A coextruded film with the composition according to Example 1, in which the cover layer A was composed as follows:
65 wt .-% component I and
35% by weight of component II

Comparative example (VB)

Example 1 is repeated. In contrast to Example 1, unmodified PET is used used instead of PETBB.

The most important parameters of the films produced in this way are shown in Table 2.

Table 2

Show after 1000 hours of weathering per side with the Atlas Cl 65 Weather Ometer the films from Examples 1 to 4 no embrittlement, no cracks and Yellowness index <10.  

The film from the comparative example is not inherently UV-stable and leaves that harmful UV light. After 1000 hours of weathering per side, this film shows Cracks and embrittlement symptoms as well as a visible yellowing.

Claims (28)

1. Multi-layer film, characterized in that it has a base layer, which contains a crystallizable, bibenzol-modified thermoplastic as the main component, and at least one matt cover layer, which contains a mixture or a blend of two components I and II. 2. Film according to claim 1, characterized in that the amount of Bibenzol-modified thermoplastics, based on the weight of the finished layers, 50 to 99.9% by weight, preferably 75 to 99% by weight, is. 3. Film according to claim 1 or 2, characterized in that it consists of a Base layer B and two cover layers A and C with the layer sequence A-B-C is constructed, the cover layers can be the same or different. 4. Film according to one or more of claims 1 to 3, characterized characterized in that they have additional intermediate layers, preferably 2nd additional intermediate layers. 5. Film according to one or more of claims 1 to 4, characterized characterized that as a thermoplastic a bibenzol-modified polyester is used. 6. Film according to one or more of claims 1 to 5, characterized characterized as bibenzol-modified polyester Polyethylene terephthalate, bibenzene-modified polybutylene terephthalate or Bibenzol-modified polyethylene naphthalate is used. 7. Film according to one or more of claims 1 to 6, characterized  characterized that as a bibenzol-modified thermoplastic Bibenzol-modified polyethylene terephthalate is used. 8. Film according to one or more of claims 1 to 7, characterized characterized that the standard viscosity SV (DCE) of the bibenzene-modified polyethylene terephthalate between 600 and 1000, preferably between 700 and 900. 9. Film according to one or more of claims 1 to 8, characterized characterized in that the bibenzenic acid content, based on the weight of the bibenzene-modified thermoplastics, 1 to 50% by weight, preferably 5 to 45 % By weight, in particular 10 to 40% by weight. 10. Film according to one or more of claims 1 to 9, characterized characterized that a top layer and any existing Intermediate layers a bibenzol-modified thermoplastic, preferred that of the base layer. 11. Film according to one or more of claims 1 to 10, characterized characterized that a top layer and any existing Intermediate layers of unmodified polyalkylene terephthalate, bibenzene-modified and / or unmodified polyalkylene naphthalate or Bibenzene-modified and / or unmodified polyalkylene terephthalate Contain polyalkylene naphthalate copolymer. 12. Film according to one or more of claims 1 to 11, characterized characterized in that as component I a thermoplastic polyester, preferably polyethylene terephthalate homopolymer, polyethylene terephthalate Copolymer or a mixture of polyethylene terephthalate homo- and / or Copolymers.   13. Film according to one or more of claims 1 to 12, characterized characterized in that a polymer is used as component II, the one Has sulfonate group. 14. Film according to one or more of claims 1 to 13, characterized in that the condensation product of the following monomers or their derivatives capable of forming polyesters is used as component II:

• a) 65 to 95 mol% isophthalic acid
• b) 0 to 30 mol% of at least one aliphatic dicarboxylic acid of the formula HOOC (CH ₂ ) _n COOH, where n is a number from 1 to 11,
• c) 5 to 15 mol% of at least one sulfomonomer which has an alkali metal sulfonate group on the aromatic part of an aromatic dicarboxylic acid, and
• d) the amount of a copolymerizable aliphatic or cycloaliphatic glycol having 2 to 11 carbon atoms necessary to form 100 mol% of condensation product.

15. Film according to one or more of claims 1 to 14, characterized characterized in that as component II b) malon, adipine, azelaine, glutaric, Sebacic, cork, amber or brassylic acid or their for the formation of Polyester-enabled derivatives or mixtures of these substances are used become. 16. Film according to one or more of claims 1 to 15, characterized characterized in that as component II c) monomers of the formula are used, where M is alkali metal, preferably Na, Li or K, Z is a trivalent aromatic radical and X and Y are carboxyl groups or Are polyester-forming equivalents.   17. Film according to one or more of claims 1 to 16, characterized characterized in that as component II d) ethylene glycol, 1,5-pentanediol, 1,6- Hexanediol, neopentyl glycol, 1,10-decanediol or cyclohexane-dimethanol, preferably ethylene glycol is used. 18. Film according to one or more of claims 1 to 17, characterized characterized in that the weight ratio of component I: component II 10: 90 to 95: 5. 19. Film according to one or more of claims 1 to 18, characterized characterized that the standard viscosity SV (DCE) of component I 500 to 800, preferably 500 to 700. 20. Film according to one or more of claims 1 to 19, characterized characterized that the standard viscosity SV (DCE) of component II 300 to 700, preferably 350 to 650. 21. Film according to one or more of claims 1 to 20, characterized characterized in that the film is functional on one or both surfaces is coated. 22. Film according to one or more of claims 1 to 21, characterized characterized in that the matt film surface has a gloss of less than 70, preferably less than 50. 23. Film according to one or more of claims 1 to 22, characterized characterized in that it has a haze of less than 40%, preferably less than 30%. 24. Film according to one or more of claims 1 to 23, characterized characterized in that the film usual additives such as antiblocking agents,  Contains stabilizers or lubricants. 25. Inherently UV-stabilized film, characterized in that it is a film according to one or more of claims 1 to 24. 26. A method for producing a film according to one or more of the claims 1 to 25, characterized in that one for the production of the film required raw materials co-extruded through a slot die, the obtained Biaxially stretched and heat-set film and, if necessary, on one or both sides coated. 27. Use of a film according to one or more of claims 1 to 25 for Manufacture of moldings. 28. Shaped body produced using a film according to one or more of claims 1 to 25.