DE10043782A1 - Ultraviolet- and cold-resistant mono- or multilayer film comprises a crystallizable bibenzoate-modified thermoplastic polymer - Google Patents

Abstract

Mono- or multilayer film comprising a crystallizable bibenzoate-modified thermoplastic polymer (I) as the major component is new. An Independent claim is also included for a process for producing the film, comprising: (1) coextruding the starting materials through a slit die; (2) biaxially stretching and thermofixing the resulting film; and (3) optionally coating the film on one or both sides.

Description

The invention relates to a transparent, biaxially oriented, partially crystalline film made of one Crystallizable, bibenzene-modified thermoplastics, a process for their production this slide and its use.

Transparent films made of crystallizable thermoplastics are known.

These films are not inherently UV stable, so that neither the films nor the articles made therefrom are suitable for outdoor use. For outdoor applications these films show yellowing and deterioration after a short time the mechanical properties due to photooxidative degradation Sunlight.

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. Under good mechanical properties is understood to mean that in the measurement of impact strength a _n Charpy (ISO 179 / 1D), no breakage occurs and that the Izod impact strength according to ISO 180 at -40 ° C 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.

The object of the present invention is to provide a transparent, biaxially oriented, To provide semi-crystalline film with a thickness of preferably 1 to 500 microns, the in addition to good stretchability in the longitudinal and transverse directions, good mechanical and optical properties, above all, have a 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 films should not yellow when used outdoors for several years, show no embrittlement or cracking on the surface and also none Have deterioration in mechanical properties. High UV stability means that the film absorbs UV light and light only in the visible Area passes.

The good optical properties preferably include high light transmission (<64%), a high surface gloss (<100), a low haze (<30%) as well a low yellow number (YID <10).

The good mechanical properties preferably include a high modulus of elasticity (E _MD <3800 N / mm ² ; E _TD <4500 N / mm ² ) and good tensile strength values (in MD <100 N / mm ² ; in TD <180 N / mm ² ) and good elongation at break values in the longitudinal and transverse directions (in MD <90%; in TD <70%).

Good stretchability includes e.g. B. that the film in its manufacture can be oriented well in both the longitudinal and transverse directions and without tears.

In addition, the film according to the invention should be recyclable, in particular without significant deterioration in the optical and mechanical properties.  

This task is solved by a transparent, biaxially oriented, partially crystalline Film with a thickness in the range of preferably 1 to 500 microns, which is the main component contains a crystallizable, bibenzene-modified thermoplastic.

The main component of the film according to the invention is a crystallizable, Bibenzol-modified thermoplastics. Suitable crystallizable or partially crystalline Bibenzol-modified thermoplastics are, for example, polyesters such as Bibenzol-modified polyethylene terephthalate (PETBB), bibenzol-modified Polybutylene terephthalate (PBTBB), bibenzene-modified polyethylene naphthalate (PENBB), with bibenzene-modified polyethylene terephthalate (PETBB) being 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) with a heating rate of 20 ° C / min, from 180 ° C to over 365 ° C, preferably from 180 ° C to 310 ° C, depending on the Bibenzolic 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 one 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 by DSC (Differential Scanning Calorimetry) with a heating rate of 10 ° C / min, from 120 ° C to 310 ° C, preferably from 140 ° C to 280 ° C, depending on the bibenzene 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 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 film according to the invention can be either single-layer or multi-layer. The The film can also be coated with various copolyesters or adhesion promoters.  

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 already yellow after production Yellowness index differences (YID) by approx. 25. Furthermore, the mechanical Properties of such a film adversely affected. Kick when stretching Problems on such. 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 yellowness index of the film compared to a polyethylene terephthalate film in Scope of measurement accuracy does not change;
• - 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 with speeds of 420 m / min can be produced reliably. This is the invention Film also economically profitable.

It should also be mentioned that the regenerated material is again used in the production of the film can be used without negatively affecting the yellowness index of the film.

The surface gloss of the film according to the invention, measured in accordance with DIN 67530 (Measuring angle 20 °), is preferably greater than 100, preferably greater than 110, the Light transmission L *, measured according to ASTM D 1003, is preferably more than 64%, preferably more than 66% and the haze of the film, measured in accordance with ASTM D 1003, is preferably less than 30%, preferably less than 25%, which for the achieved UV stability is surprisingly good.

The standard viscosity SV (DCE) of the preferred one Bibenzol-modified polyethylene terephthalate, measured in dichloroacetic acid DIN 53728 is between 600 and 1000, preferably between 700 and 900.

The intrinsic viscosity IV (DCE) is calculated from the standard viscosity SV (DCE) as follows:

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

The bulk density, measured according to DIN 53466, is preferably between 0.75 kg / dm ³ and 1.0 kg / dm ³ , and particularly preferably between 0.80 kg / dm ³ and 0.90 kg / dm ³ .

The polydispersity of the bibenzol-modified, which is also preferred Polyalkylene naphthalate or bibenzene-modified polyalkylene terephthalate Mw / Mn measured by GPC is preferably between 1.5 and 4.0 and particularly preferably between 2.0 and 3.5.

The transparent film according to the invention can be either single-layer or be multilayered.

In the multilayer embodiment, the film is composed of at least one core layer and built up at least one top layer, in particular a three-layer A-B-A or A-B-C structure is preferred, the cover layers A and C being equal to or can be different.

For this embodiment, it is advantageous if the bibenzol-modified thermoplastic the core layer has a similar standard viscosity as the bibenzol-modified one Thermoplastic of the outer layers that adjoin the core layer.

In a further special embodiment, the cover layers can also be made of an unmodified polyalkylene terephthalate homopolymer, from one bibenzene-modified and / or unmodified polyalkylene naphthalate polymers or from a bibenzene-modified and / or unmodified polyalkylene therapy- Polyalkylene naphthalate copolymers or compound exist. Even in these cases PET and PEN are preferred polymers to use.

In this embodiment, the thermoplastics of the cover layers have preferred standard viscosities similar to z. B. the bibenzol-modified Polyalkylene terephthalate of the core layer.  

The film can also be coated on at least one side with a scratch-resistant coating Copolyester or be provided with an adhesion promoter.

According to the invention, 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, preferably 20 to 700 nm, in particular 30 to 50 nm. The coating is preferably applied in-line, ie during the film production process, expediently before transverse stretching. Application by means of the so-called "reverse gravure-roll coating" method, in which the coatings can be applied extremely homogeneously in the layer thicknesses mentioned, is particularly 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 such. B. the film is sealable, printable, metallizable, sterilizable, antistatic, or they 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 that add 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 C10-C18 fatty acids, butadiene copolymers Acrylonitrile or methyl methacrylate, methacrylic acid, acrylic acid or their esters The substances / compositions which impart the additional functionality can contain the usual additives, such as antiblocking agents, pH stabilizers in amounts of preferably 0.05% by weight to 5 Wt .-%, preferably 0.1 wt .-% to 3 wt .-%. Wt .-% are each based on the weight of the coating agent (z. B. solution, emulsion, dispersion).

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 preferred layer thicknesses 5 to 100 nm, preferably 20 to 70 nm, in particular 30 to 50 nm.

Weathering tests have shown that the films according to the invention themselves Weathering tests with a projected 5 to 7 years of outdoor use in general no yellowing, no embrittlement, no loss of gloss on the surface, none Cracking on the surface and no deterioration of the mechanical Have properties.

During the production of the film, it was found that the film of the invention excellent orientation in the longitudinal and transverse directions without tears. Furthermore no outgassing was found in the production process, which is very advantageous is.

In addition, measurements of cold resistance (DIN 53372) showed that the film according to the invention down to -200 ° C meets the requirements of the standard, d. H. Not brittle.

Furthermore, the film according to the invention is without environmental pollution and without loss the mechanical properties can be easily recycled, which makes them unique for example for use as short-lived advertising signs or others Promotional items are suitable.

The film according to the invention can be produced, for example, according to a known extrusion or coextrusion processes take place in an extrusion line.  

The films can be made from a bibenzol-modified according to known methods Thermoplastics with possibly further raw materials / polymers and / or further usual ones Additives in the usual amount of approx. 0.1 to a maximum of 10% by weight both as monofilms as well as multi-layer, possibly coextruded films with the same or different trained surfaces are produced, one surface for example is pigmented and the other surface contains no pigment. Likewise, one or both surfaces of the film according to known methods with a conventional one functional coating.

The further raw materials / additives mentioned are preferred by means of the so-called Masterbatch technology added during extrusion, but you can also use it directly Raw material manufacturers are incorporated.

In the preferred extrusion process for producing the film according to the invention, the melted bibenzol-modified thermoplastic is extruded through a slot die and quenched as a largely amorphous pre-film on a chill roll. This film is then heated again and stretched in the longitudinal and transverse directions or in the transverse and in the longitudinal direction or in the longitudinal, in the transverse and again in the longitudinal direction and / or transverse direction. The stretching temperatures are generally T _g + 10 ° C to T _g + 60 ° C (T _g = glass temperature), the stretching ratio of the longitudinal stretching is usually 2 to 6, in particular 3 to 4.5, that of the transverse stretching is approx 2 to 5, in particular in the case of 3 to 4.5, and that of the second longitudinal stretching which may be carried out at 1.1 to 3. The first longitudinal stretching can, if appropriate, be carried out simultaneously with the transverse stretching (simultaneous stretching). This is followed by the heat setting of the film at oven temperatures of approx. 200 to 280 ° C, in particular at 220 to 270 ° C. The film is then cooled and wound up.

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 and for a variety of other moldings.

Because of the good UV stability and low-temperature resistance, the invention is suitable Film also for outdoor applications, such as. B. for greenhouses, canopies, Exterior cladding, covers, applications in the construction sector, applications in Cooling and freezing area and for illuminated advertising profiles.

The invention is explained in more detail below on the basis of exemplary embodiments.

The individual properties were measured in accordance with the following standards or procedure.

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 20 ° according to DIN 67530.

light transmission

Below the light transmission is the ratio of the total transmitted light to understand the amount of incident light.

The light transmission is carried out using the "Hazegard plus" measuring device in accordance with ASTM D 1003 measured.

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 less than 2.5 °.

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

surface defects

The surface defects are determined visually.

Mechanical properties

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

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

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 will measured according to DIN 6167.

cold resistance

The cold resistance is determined according to DIN 53372.

The following examples and comparative examples are each single-layer, transparent foils of different thickness, on a Extrusion line to be manufactured.

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 in terms of mechanical properties, discoloration, surface defects, of turbidity and gloss checked.

Examples example 1

A 50 µm thick, transparent film is produced, which is the main component Contains PETBB and 0.1% by weight Sylobloc®.

The Sylobloc® used (SiO ₂ , Grace, Germany) is added in the form of a masterbatch which, in addition to PETBB, contains 10,000 ppm Sylobloc.

The PETBB from which the transparent film is made has one Standard viscosity SV (DCE) of 810, indicating an intrinsic viscosity IV (DCE) of  Corresponds to 0.658 dl / g. The bisbenzene acid content is 15% by weight Glass transition temperature is 86 ° C.

The transparent bibenzene-modified PET film produced has the following property profile:
Thickness: 50 µm
Surface gloss 1st page: 152
(Measuring angle 20 °) 2nd side: 153
Light transmission: 92%
Turbidity: 4.1%
Surface defects per m ² : none
Longitudinal modulus of elasticity: 4350 N / mm ²
E-module across: 5700 N / mm ²
Longitudinal tensile strength: 180 N / mm ²
Tear strength across: 270 N / mm ²
Elongation at break: 170%
Elongation at break across. 85%
Yellowness Index (YID): 3.0
Cold resistance: <-200 ° C
Absorption of UV light: <370 nm

After 1000 hours of weathering per side with Atlas Ci 65 Weather Ometer, the bibenzol-modified PET film shows the following properties:
Thickness: 50 µm
Surface gloss 1st page: 145
(Measuring angle 20) 2nd side: 141
Light transmission: 91.1%
Turbidity: 4.3%
Surface defects: none
(Cracks, embrittlement)
Yellow number (YID): 3.6
E-module longitudinal: 4150 N / mm ²
E-module transverse: 5500 N / mm ²
Longitudinal tensile strength: 170 N / mm ²
Tear strength across: 250 N / mm ²
Elongation at break: 150%
Elongation at break: 75%
Cold resistance: <-200 ° C

Example 2

Analogous to Example 1, a transparent 50 μm thick monofilm is produced. in the In contrast to example 1, 25% by weight of self-regenerated material is used.

After the longitudinal stretching, the film is coated on both sides with an aqueous dispersion by means of the “reverse gravure-roll coating” method. In addition to water, the dispersion contains 4.2% by weight of hydrophilic polyester (5-Na-sulfoisophthalic acid-containing PET / IPA polyester, SP41®, from Ticona, USA), 0.15% by weight of colloidal silicon dioxide (Nalco 1060®, Deutsche Nalco Chemie, Germany) as an antiblocking agent and 0.15% by weight ammonium carbonate (Merck, Germany) as a pH buffer. The wet application weight is 2 g / m ² per coated side. After the transverse stretching, the calculated thickness of the coating is 40 nm.

The transparent bibenzene-modified PET film produced has the following property profile:
Thickness: 50 µm
Surface gloss 1st side: 150
(Measuring angle 20 °) 2nd side: 155
Light transmission: 91%
Turbidity: 4.2%
Surface defects per m ² : none
Modulus of elasticity longitudinal: 4400 N / mm ²
E-module across: 5700 N / mm ²
Longitudinal tensile strength: 185 N / mm ²
Tear strength across: 265 N / mm ²
Elongation at break: 170%
Elongation at break across: 80%
Yellow number (YID): 3.2
Cold resistance: <-200 ° C
Absorption of UV light: <370 nm

The adhesion of this film to printing inks or vapor-deposited metals is significantly improved compared to an untreated film.

After 1000 hours of weathering per side with Atlas Ci 65 Weather Ometer, the bibenzol-modified PET film shows the following properties:
Thickness: 50 µm
Surface gloss 1st page: 145
(Measuring angle 20) 2nd side: 141
Light transmission: 90.4%
Turbidity: 4.5%
Surface defects: none
(Cracks, embrittlement)
Yellow number (YID): 3.8
E-module longitudinal: 4150 N / mm ²
E-module across: 5400 N / mm ²
Longitudinal tensile strength: 170 N / mm ²
Tear strength across: 245 N / mm ²
Elongation at break: 155%
Elongation at break: 75%
Cold resistance: <-200 ° C

Comparative Example 1

Analogously to Example 1, a 50 μm thick monofilm is produced from PET homoplymer. The SV value of the unmodified PET homopolymer used is also included here 810th

The film is not coated in-line.

The transparent PET film produced has the following property profile:
Thickness: 50 µm
Surface gloss 1st side: 160
(Measuring angle 20 °) 2nd side: 155
Light transmission: 92%
Turbidity: 4.0%
Surface defects per m ² : none
Longitudinal modulus of elasticity: 4450 N / mm ²
E-module across: 5800 N / mm ²
Longitudinal tensile strength: 180 N / mm ²
Tear strength across: 260 N / mm ²
Elongation at break: 180%
Elongation at break across: 85%
Yellowness Index (YID): 3.0
Cold resistance: <-200 ° C
Absorption of UV light: <300 nm

The adhesion of this film to printing inks or vapor-deposited metals is significantly worse than in Example 2.  

After 1000 hours of weathering per side with Atlas CI 65 Weather Ometer, the Foil on the surfaces cracks and embrittlement. A precise one Property profile - especially with regard to the mechanical properties - can therefore can no longer be measured. The film also shows a visually visible one Yellowing. Due to the brittleness, the cold resistance of this film cannot be determine.

Claims (20)

1. Single or multilayer film, characterized in that it contains a crystallizable, bibenzol-modified thermoplastic as the main component. 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 that as a thermoplastic a bibenzol-modified polyester is used. 5. Film according to one or more of claims 1 to 4, characterized characterized as bibenzol-modified polyester Polyethylene terephthalate, bibenzene-modified polybutylene terephthalate or Bibenzol-modified polyethylene naphthalate is used. 6. Film according to one or more of claims 1 to 5, characterized characterized that as a bibenzol-modified thermoplastic Bibenzol-modified polyethylene terephthalate is used. 7. Film according to one or more of claims 1 to 6, characterized characterized that the standard viscosity SV (DCE) of the  bibenzene-modified polyethylene terephthalate between 600 and 1000, preferably between 700 and 900. 8. Film according to one or more of claims 1 to 7, 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. 9. Film according to one or more of claims 1 to 8, characterized characterized that the top layers have a bibenzol-modified Thermoplastics, preferably those of the base layer, contain. 10. Film according to one or more of claims 1 to 9, characterized characterized that the top layers are unmodified Polyalkylene terephthalate, bibenzene-modified and / or unmodified Polyalkylene naphthalate or bibenzene-modified and / or unmodified Contain polyalkylene terephthalate-polyalkylene naphthalate copolymer. 11. Film according to one or more of claims 1 to 10, characterized characterized in that the polymers of the base and cover layers are similar Have standard viscosities. 12. Film according to one or more of claims 1 to 11, characterized characterized in that the film is functional on one or both surfaces is coated. 13. Film according to one or more of claims 1 to 12, characterized characterized that they have a surface gloss greater than 100, preferably greater than 110.   14. Film according to one or more of claims 1 to 13, characterized characterized that she prefers a light transmission of more than 64% greater than 66%. 15. Film according to one or more of claims 1 to 14, characterized characterized in that it has a haze of less than 30%, preferably less than 25%. 16. Film according to one or more of claims 1 to 15, characterized characterized in that the film usual additives such as antiblocking agents, Contains stabilizers or lubricants. 17. Inherently UV-stabilized film, characterized in that it is a film according to one or more of claims 1 to 16. 18. A method for producing a film according to one or more of the claims 1 to 17, characterized in that one for the production of the film required raw materials extruded through a slot die or at multilayer structure coextruded, the film obtained biaxially stretched and heat-set and optionally coated on one or both sides. 19. Use of a film according to one or more of claims 1 to 17 Manufacture of moldings. 20. Moldings produced using a film according to one or more of claims 1 to 17.