DE102005058919A1 - Ultraviolet-stabilized biaxially oriented polyester film laminate for packaging, lamination with polyester or metal, cladding, display, greenhouse or roofing has particles in mat outer layer but not in sealable layer on other side of base - Google Patents

Abstract

In laminated, UV-stabilized, biaxially oriented polyester film, having base layer(s) (B) with sealable layer (A) and mat layer (C) on opposite surfaces, (A) contains less than 0.1 wt.% external particles; and (C) contains a polyester with 6-30 mole-% isophthalic acid units and 1.0-7.0 wt.%, with respect to total (C), pigment particles of average diameter (d50) of 2-10 mu m with scatter, expressed as SPAN 98, in the 1.2-2 range. An independent claim is included for production of the laminated film.

Description

The The invention relates to a one-sided matte, one-sided sealable and UV-stabilized, biaxially oriented polyester film consisting of a base layer (B) and applied on both sides of this base layer cover layers (A) (sealable) and (C) (dull). Furthermore contains the foil in addition at least one UV stabilizer as light stabilizer. The invention further relates to a process for producing the film and its Use.

The inventive films and articles made therefrom are particularly suitable for outdoor applications such as. For Greenhouses or canopies. Furthermore, the films are very good for the cover and thus for Protection of metallic surfaces, on which the films are heat sealed become. For outdoor applications show films that contain no UV-absorbing materials after a short time, yellowing and deterioration the mechanical properties due to a photo-oxidative degradation through the sunlight. Furthermore Such films do not provide protection for the underlying substrate. The article (e.g., inventive film On metallic sheet metal is additionally through the matte surface appealing visual character.

UV-stabilized sealable, biaxially oriented polyester films of the prior art are known.

In EP-A 1 125 732 describes a UV-stabilized, biaxially oriented, sealable Polyester film with a base layer (B), a sealable topcoat (A) and a non-sealable Cover layer (C) described. The sealable cover layer (A) has a Seal temperature of maximum 110 ° C and a seal strength of at least 1.3 N / 15 mm film width. The topographies of the two Coatings (A) and (C) are characterized by certain features. The foil contains additionally at least one UV absorber in effective amounts or mixtures from different UV absorbers. In Comparative Example 1, a film is described in which the Sealant layer is pigment-free. The film according to the comparative example has unacceptable handling and processing behavior, Furthermore does not show you what you want unilateral, dull appearance.

In EP-B 0 920 381 discloses a coextruded, multilayered polyester film described that a sealable Cover layer and a non-sealable base layer has. The base layer can consist of one or more layers be constructed, wherein one of the layers with the sealable layer is in contact. The other (outer) layer then forms the second, non-sealable topcoat. The sealable top layer can be made from isophthalic acid and terephthalic acid-containing Copolyesters exist. The film also contains a UV absorber, the the base layer in an amount of 0.1 to 10 wt .-% added becomes. The base layer of this film is equipped with conventional antiblocking agents. The film is characterized by a good sealability, but has not the wished Processing behavior and has deficits in the optical properties on. For example, the haze of the film is given as <75%. The film can also have a matte surface, it has but then a high turbidity, the undesirable is.

Also are known in the art on one side matte, one-sided siegelfähge, biaxially oriented polyester films containing at least one UV absorber exhibit.

EP-A 1 274 579 describes a UV-stabilized, one-sided matt and one-side sealable polyester film. The sealable layer of this film consists essentially of isophthalic and terephthalic acid containing copolyesters. Their surface is described by a certain topography. The opposite side of this page is dull and filled with inert particles. In the preferred embodiment, the concentration of inert particles in this layer is between 1.0 and 18% by weight. The polymer used for this layer is polyethylene terephthalate, preferably a mixture of polyethylene terephthalate and a copolyester (component I). The copolyester contains isophthalic acid, an aliphatic acid and a sulfomonomer. The film according to this invention is characterized by a desirable high transparency, but can be produced only at high cost. Due to the high concentration of inert particles used in the polyethylene terephthalate or in the mixture to obtain a polymer having a high crosslinking density, in which the stretching forces are significantly higher than in a polymer, without the inert particles (see. 1 ). The consequence of this are comparatively many tears in the production of the film, which are undesirable. In addition, the film is insufficiently UV-stabilized, since according to the examples given, only the two outer layers are equipped with a UV stabilizer. Comparative Example 1 describes a film in which the sealing layer is pigment-free. The film according to the comparative example has an unacceptable action and an unacceptable processing performance they can not be produced according to commercial criteria.

• • eine verbesserte Siegelfähigkeit gegenüber sich selbst, gegenüber Substraten aus APET, A/CPET, CPET und Metallen,
• • eine verbesserte UV-Stabilität,
• • verbesserte optische Eigenschaften (Trübung, Mattgrad),
• • eine gute Herstellbarkeit (Streckbarkeit) und
• • eine verbesserte Wickelung und verbessertes Verarbeitungsverhalten

auszeichnet.
(APET = amorphes Polyethylenterephthalat (PET); CPET = kristallines PET; A/CPET = zweischichtiges Laminat, innen APET, außen CPET (bei einer Schale))The object of the present invention was therefore to provide a one-sided matte, one-side sealable, UV-stabilized, biaxially oriented polyester film which does not have the disadvantages of the films according to the prior art and in particular by

• An improved sealability to itself over substrates of APET, A / CPET, CPET and metals,
• An improved UV stability,
• • improved optical properties (haze, mattness),
• • good manufacturability (ductility) and
• • improved winding and improved processing behavior

distinguished.
(APET = amorphous polyethylene terephthalate (PET); CPET = crystalline PET; A / CPET = two-layer laminate, inside APET, outside CPET (in one shell))

improved sealability means a minimum sealing temperature of the cover layer A with respect to itself of <110 ° C, preferably <108 ° C and especially preferably <106 ° C and a Sealing seam strength of this outer layer A against itself from 1.5 to 10 N / 15 mm, preferably from 1.6 to 10 N / 15 mm, and more preferably from 1.7 to 10 N / 15 mm. Against an APET substrate, the minimum sealing temperature the cover layer A <140 ° C, preferably <139 ° C and especially preferably <138 ° C and the seal seam strength of this cover layer A over one A / CPET substrate 1.5 to 10 N / 15 mm, preferably from 1.6 to 10 N / 15 mm and more preferably from 1.7 to 10 N / 15 mm. A special The purpose of the present invention was to seal the film to metals, such as steel or aluminum, coated with lacquer Steel, chromed, galvanized or tinned steel (tinplate), to improve. Furthermore should do it Care should be taken that the film is well windable and on high-speed machines can be processed. In the preparation of the film should also be guaranteed be that accumulating waste material as Regenerat in one Amount of preferably up to 60 wt .-%, based on the total weight the film, can be returned to the manufacturing process without that while the physical and optical properties of the film negative to be influenced.

There the film especially for the outdoor application and / or critical indoor applications, it should be one high UV stability exhibit. A high UV stability means that the slides by sunlight or other UV radiation not or only extremely little damage. In particular, should the slides at perennial outdoor use not yellowing, no embrittlement or cracking of the surface and also have no deterioration of the mechanical properties. High UV stability thus means that the film absorbs the UV light and light only let through in the visible area.

• a) zumindest die Basisschicht (B) und die matte Deckschicht (C) mindestens einen UV-Absorber enthält,
• b) die siegelfähige Deckschicht (A) weniger als 0,01 Gew.-% Partikel enthält (bezogen auf das Gesamtgewicht der Deckschicht (A)) und
• c) die matte Deckschicht (C) i. einen Polyester enthält, der 6 bis 30 Mol-% Isophthalsäureeinheiten aufweist, bezogen auf die Gesamtsäuremenge des Polyesters in dieser Schicht, und ii. ein Pigment enthält, das durch die folgenden Merkmale gekennzeichnet ist: • der mittlere Durchmesser der Partikel (d₅₀-Wert) liegt im Bereich von 2 bis 10 µm, • die Streuung der Partikelgrößenverteilung, ausgedrückt durch den SPAN 98, liegt im Bereich von 1,2 bis 2, und • die Konzentration der Partikel liegt im Bereich von 1,0 bis 7,0 Gew.-%, bezogen auf das Gesamtgewicht der Deckschicht (C).

The object is achieved by providing a one-sided matte, one-side sealable, biaxially oriented polyester film having a base layer (B), a sealable top layer (A) and a matte top layer (C), wherein

• a) at least the base layer (B) and the matte top layer (C) contains at least one UV absorber,
• b) the sealable outer layer (A) contains less than 0.01% by weight of particles (based on the total weight of the outer layer (A)) and
• c) the matte topcoat (C) i. a polyester containing from 6 to 30 mol% of isophthalic acid units based on the total amount of acid of the polyester in this layer, and ii. contains a pigment characterized by the following features: the average diameter of the particles (d ₅₀ value) is in the range of 2 to 10 μm, the dispersion of the particle size distribution, expressed by the SPAN 98, is in the range of 1 , 2 to 2, and • the concentration of the particles is in the range of 1.0 to 7.0 wt .-%, based on the total weight of the outer layer (C).

Of the (The) UV stabilizer (s) is (are) suitably used as a masterbatch (e) directly added during film production, the concentration the UV stabilizer (s) in the range of 0.01 to 5.0 wt .-%, preferably 0.1 to 4.0 wt .-% and particularly preferably 1.5 to 2.5 % By weight, based on the weight of the respective layer of the used Polyester, lies (lie).

Pigment also means antiblocking agent, filler, called external or inert particles, which by the characterized parameters are characterized. Typical pigments 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, LiF, calcium, barium, zinc or manganese salts Dicarboxylic acids, titanium dioxide, kaolin or crosslinked polystyrene or acrylate particles.

A matt film according to the invention has gloss values on the matt surface of the film of <70, preferably <60 and particularly preferably <50 (at a measuring angle of 60 °). The average roughness R _{a of} this surface is 150-1000 nm, preferably 175-950 nm and particularly preferably 200-900 nm.

According to the invention At least three layers of film and comprises the base layer (B), the sealable Topcoat (A) and the matte topcoat (C).

Material for base layer (B)

The Base layer (B) of the film is preferably at least 90% by weight made of a thermoplastic polyester. Suitable for this are polyester Ethylene glycol and terephthalic acid (= Polyethylene terephthalate, PET), from ethylene glycol and naphthalene-2,6-dicarboxylic acid (= polyethylene 2,6-naphthalate, PEN), 1,4-bis-hydroxymethyl-cyclohexane and terephthalic acid (= poly (1,4-cyclohexanedimethylene terephthalate, PCDT) and ethylene glycol, naphthalene-2,6-dicarboxylic acid and Biphenyl-4,4'-dicarboxylic acid (= polyethylene-2,6-naphthalate bibenzoate, PENBB). Particularly preferred are polyesters which are at least 90 Mol%, preferably at least 95 mol%, of ethylene glycol and terephthalic acid units or consist of ethylene glycol and naphthalene-2,6-dicarboxylic acid units. The remaining monomer units are derived from other aliphatic, cycloaliphatic or aromatic diols or dicarboxylic acids.

Suitable other aliphatic diols are, for example, diethylene glycol, triethylene glycol, aliphatic glycols of the general formula HO- (CH ₂ ) _n -OH, where n is 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 having up to 6 carbon atoms. Of the cycloaliphatic diols, mention may be made of cyclohexanediols (in particular cyclohexane-1,4-diol). Suitable other aromatic diols correspond, for example, to the formula HO-C ₆ N 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 , in particular diphenylacetylene-4,4'-dicarboxylic acid, or stilbene-x, x'-dicarboxylic acids. Of the cycloaliphatic dicarboxylic acids, mention may be made of cyclohexanedicarboxylic acids, in particular cyclohexane-1,4-dicarboxylic acid. Of the aliphatic dicarboxylic acids, the (C ₃ to C ₁₉ ) alkanedioic acids are particularly suitable, it being possible for the alkane part to be straight-chain or branched.

The Preparation of the polyesters may e.g. after the transesterification process respectively. It is based on dicarboxylic acid esters and diols, the with the usual Transesterification catalysts, such as zinc, calcium, lithium, magnesium and manganese salts, to be implemented. The intermediates will be then generally more common in the presence Polycondensation catalysts, such as antimony trioxide or titanium salts, polycondensed. The production can be just as good after the direct esterification process in the presence of polycondensation catalysts. there starting directly from the dicarboxylic acids and diols. Polyester according to the invention are available as commercial products.

Sealable topcoat (A)

The sealable outer layer (A) applied by coextrusion to the base layer (B) preferably consists essentially of copolyesters which are predominantly composed of isophthalic and terephthalic acid units and of ethylene glycol units. The remaining monomer units are derived from other aliphatic, cycloaliphatic or aromatic diols or dicarboxylic acids, as they may also occur in the base layer. The preferred copolyesters which provide the desired sealing properties are those composed of ethylene terephthalate and ethylene isophthalate units. The proportion of ethylene terephthalate is preferably 60 to 95 mol% and the corresponding proportion of ethylene isophthalate 40 to 5 mol%. Also preferred are copolyesters in which the proportion of ethylene terephthalate 65 to 90 mol% and the corresponding proportion of ethylene isophthalate 35 to 10 mol%, and are quite preferred Copolyesters in which the proportion of ethylene terephthalate 70 to 85 mol% and the corresponding proportion of ethylene isophthalate 30 to 15 mol%.

The sealable Cover layer (A) contains less than 0.01%, preferably no external particles. In this Case is the seal opposite yourself and opposite the above materials best. Between the sealing layer (A) and the substrate form no bubbles and the seal is the entire surface. Otherwise, e.g. through the tips of the pigments cavities which worsen the seal and lead to optical defects in the lead on laminated film.

Sealing properties of the sealable Cover layer (A)

The desired Sealing properties of the top layer (A) are believed to be from the Combination of the chemical composition of the copolyester used, the top layer thickness and the topography.

The sealable Cover layer (A) has opposite itself a sealing temperature of less than 110 ° C and a Seal seam strength (measured at 130 ° C) of at least 1.5 N / 15 mm film width, opposite a substrate of APET a sealing temperature of less 140 ° C and a seal strength (measured at 140 ° C) of at least 1.5 N / 15 mm film width. The best sealing properties of the film are obtained, if the copolyester no further additives, in particular no inorganic or organic pigment. For this case you get at given copolyester and given layer thickness the lowest Seal initiation temperature and the highest seal strength.

If the sealable Topcoat (A) smallest amounts of pigment are added, so it has to be cheap proven to use the same antiblocking agent as for the topcoat (C).

Matte topcoat (C)

The by coextrusion on the base layer (B) applied matte topcoat (C) is preferably predominant built on the basis of polyester. According to the invention, the matt covering layer (C) contains a polyester containing 6 to 28 mol% of isophthalic acid, preferably 8 to 26 mol% of isophthalic acid and particularly preferably 10 to 24 mol% of isophthalic acid, based on the total amount of acid of the polyester in this layer. The remaining monomer units come from other aliphatic, cycloaliphatic or aromatic dicarboxylic acids or diols, as they can also occur in the base layer and have already been described there. Those described for the base layer (B) Thus, polyesters are basically after appropriate modification also suitable for the outer layer (C).

Of the Raw material for leaves the cover layer (C) For example, about Copolymerization of the individual monomers or on masterbatches different Produce individual polymers as a mixture or as a blend. Prefers is the production over Masterbatches of various individual polymers as a mixture or as Blend.

In a preferred embodiment of the invention the matte topcoat (C) a copolyester consisting of terephthalate and isophthalate units and composed of ethylene glycol units is. The proportion of terephthalate units in this copolyester, based on the total amount of acid, is preferably 72 to 94 mol% and the corresponding proportion of isophthalate units 28 to 6 mol%. Particularly preferred among these are copolyesters, in which the proportion of terephthalate units 74 to 92 mol% and the corresponding proportion of isophthalate units 26 to 8 mol% is. Very preferred are those copolyesters in which the proportion of Terephthalate units 76 to 90 mol% and the corresponding proportion of isophthalate units is 24 to 10 mol%.

If be available for the remaining proportion of the polymers present in the cover layer (C) in principle used the same polymers as previously described for the base layer (B) were.

surprisingly It has been shown that when using the previously described Raw materials for the cover layer (C) receives a film with a particularly low haze.

In particular, it has surprisingly been found that when using the raw materials described above for the outer layer (C) receives a film that can be produced process-safe. The number of film breaks is now comparable to that in the production of standard polyester film in which the proportion of pigments in this layer is significantly lower. Due to the special selection of the raw material in the layer (C), the stretching forces have become significantly lower (cf. 2 ).

• a) Die matte Deckschicht (C) enthält Partikel mit einem Partikeldurchmesser d₅₀ von 2,0 bis 10 µm. Es hat sich als besonders vorteilhaft erwiesen, Teilchen mit einem mittleren Partikeldurchmesser d₅₀ von 2,2 bis 9 µm, bevorzugt von 2,4 bis 8 µm und besonders bevorzugt von 2,6 bis 7 µm zu verwenden. Bei der Verwendung von Teilchen mit einem Durchmesser, der unterhalb 2,0 µm liegt, stellt sich (bei vergleichbaren Konzentrationen) eine erhöhte Trübung ein. Teilchen mit einem Durchmesser größer als 10 µm verursachen in der Regel Filterprobleme.
• b) Die matte Deckschicht (C) enthält Partikel, deren Durchmesser eine Streuung aufweisen, die durch einen SPAN98 ≤ 2,0 beschrieben wird (Definition des SPAN98, siehe Messvorschrift). Bevorzugt ist der SPAN98 ≤ 1,9 und besonders bevorzugt ist der SPAN98 ≤ 1,8. Enthält die Deckschicht (C) der Folie dagegen ein Partikelsystem, bei dem der SPAN98 größer als 2,0 ist, so wird der Glanz der Deckschicht (C) höher, was unerwünscht ist. Ist der SPAN98 kleiner als 1,2 sind, so wird die Wicklung der Folie schlechter, sie neigt beispielsweise zum ,Verblocken'.
• c) Erfindungsgemäß enthält die Deckschicht (C) Partikel in einer Konzentration von 1,0 bis 7,0 Gew.-%, bezogen auf das Gesamtgewicht dieser Schicht. Bevorzugt beträgt die Konzentration der Partikel 2,0 bis 6,5 Gew.-% und besonders bevorzugt 3,0 bis 6,0 Gew.-%. Enthält die Deckschicht (C) der Folie dagegen ein Partikelsystem, bei dem die Partikel in einer Konzentration von weniger als 1,0 Gew.-% vorliegen, so ist sie für eine Anwendung als Mattfolie weniger geeignet. Enthält dagegen die Deckschicht (C) der Folie ein Partikelsystem, bei dem die Partikel in einer Konzentration von mehr als 7,0 Gew.-% vorliegen, so wird die Trübung der Folie zu groß.

To obtain the desired mattness of the desired degree of matting, the topcoat (C) additionally contains a pigment characterized by the following set of parameters:

• a) The matte outer layer (C) contains particles with a particle diameter d ₅₀ from 2.0 to 10 microns. It has proved to be particularly advantageous to use particles having a mean particle diameter d ₅₀ of 2.2 to 9 microns, preferably from 2.4 to 8 microns and more preferably from 2.6 to 7 microns. Using particles with a diameter below 2.0 μm results in increased turbidity (at comparable concentrations). Particles with a diameter greater than 10 microns usually cause filter problems.
• b) The matt top layer (C) contains particles whose diameters have a scattering which is described by a SPAN98 ≤ 2.0 (definition of the SPAN98, see measuring instructions). Preferably, the SPAN98 is ≦ 1.9 and more preferably the SPAN98 is ≦ 1.8. In contrast, if the cover layer (C) of the film contains a particle system in which the SPAN98 is greater than 2.0, the gloss of the cover layer (C) becomes higher, which is undesirable. If the SPAN98 is smaller than 1.2, the winding of the film becomes worse, for example, it tends to become blocked.
• c) According to the invention, the cover layer (C) contains particles in a concentration of 1.0 to 7.0 wt .-%, based on the total weight of this layer. The concentration of the particles is preferably from 2.0 to 6.5% by weight and more preferably from 3.0 to 6.0% by weight. On the other hand, if the covering layer (C) of the film contains a particle system in which the particles are present in a concentration of less than 1.0% by weight, it is less suitable for use as a matt film. If, on the other hand, the cover layer (C) of the film contains a particle system in which the particles are present in a concentration of more than 7.0% by weight, the haze of the film becomes too large.

typical favoring the degree of matting of the film and thus preferred particle systems 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, alumina, Lithium fluoride, calcium, barium, zinc or manganese salts of the used dicarboxylic acids, Titanium dioxide, kaolin or crosslinked polymer particles, e.g. polystyrene or acrylate particles.

In addition, other pigment systems, but with a smaller d ₅₀ value than the main pigment system, can (additionally) be incorporated into the cover layer C. If, however, the d ₅₀ values and / or SPAN98 values of the main pigment system deviate from the abovementioned values or if such a pigment is not present, the disadvantages described above arise.

Preferred particles are synthetically produced SiO ₂ particles (in colloidal form). These particles are very well integrated into the polymer matrix and produce only few vacuoles (cavities). Vacuoles are formed on the particles in the biaxial orientation, generally causing turbidity, and are therefore not very suitable for the present invention. For the (synthetic) preparation of the SiO ₂ particles (also called silica gel), first sulfuric acid and sodium silicate are mixed together under controlled conditions to form hydrosol. This eventually forms into a hard, transparent mass known as a hydrogel. After segregation of the by-produced sodium sulfate by a washing process, it can be dried and further processed. By controlling the wash water pH and the drying conditions, the important physical parameters such as pore volume, pore size and the size of the surface of the resulting silica gel can be varied. The desired particle size (eg the d ₅₀ value) and particle size distribution (SPAN98) are obtained by suitable grinding of the silica gel (eg mechanically or hydromechanically). Manufacturers of such particles are, for example, the companies Grace (USA), Fuji (Japan), Degussa (Germany) or Ineos (Great Britain).

The matte topcoat (C) is further characterized in a preferred embodiment by the following set of parameters: The roughness of the matte side of the film, expressed by its R _a , is in the range of 150 to 1000 nm, preferably 175 to 950 nm, more preferably from 200 to 900 nm. Lower values than 150 nm have negative effects on the mattness of the surface, larger values than 1000 nm impair the optical properties of the film.

Of the Coefficient of friction (COF) of the matte side of the film (against itself itself) is less than 0.45, preferably less than 0.40 and especially preferably less than 0.35.

UV stabilizer

in the Principle can all organic and inorganic UV stabilizers suitable for incorporation in Polyesters are suitable selected become. Such suitable UV stabilizers are known and e.g. in WO 98/06575, in EP-A 0 144 878, in EP-A 0 031 202, EP-A 0 031 203 or in EP-A 0 076 582 described in more detail.

UV stabilizers, i.e. UV absorbers as light stabilizers are generally chemical Compounds involved in the physical and chemical processes the light-induced degradation can intervene. Carbon black, titanium dioxide, zinc oxide (cf. EP-B 1 368 405) and other pigments may partially protect against light cause. However, these substances are unsuitable for transparent films, as they discolor or color change. For transparent Foils are suitable only organic and organometallic compounds, the thermoplastic to be stabilized no or only an extreme slight color or color change to lend.

suitable UV stabilizers are those which are at least 70%, preferably 80%, more preferably 90%, of the UV light in the wavelength range from 180 nm to 380 nm, preferably 280 to 360 nm. These are particularly suitable if they are in the temperature range from 260 to 300 ° C are thermally stable, i. do not decompose and not outgassing to lead. Suitable examples are 2-hydroxybenzophenones, 2-hydroxybenzotriazoles, organo-nickel compounds, salicylic acid esters, cinnamic acid ester derivatives, resorcinol monobenzoates, oxanilides, hydroxybenzoates, sterically hindered amines and / or triazines, wherein the 2-hydroxybenzotriazoles and the triazines are preferred.

In a preferred embodiment contains the film according to the invention as a UV-absorbing substance 0.01 to 5.0% by weight of 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5- (hexyl) oxy-phenol or 0.01 to 5.0% by weight of 2,2'-methylenebis (6- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) -phenol (in each case based on the weight of the polyester of the respective layer). It can also mixtures of these two UV stabilizers or mixtures of at least one of these two UV stabilizers with others UV stabilizers used wherein the total concentration of light stabilizer is preferably in the range of 0.01 to 5.0 wt .-%, based on the weight of thermoplastic polyester of the respective layer is located.

According to the present Invention is the UV stabilizer at least in the base layer (B) and in the non-sealable Cover layer (C) included. However, if necessary, the sealable topcoat may also be used (A) equipped with UV stabilizers be. The concentration of the stabilizer (s) relates doing so on the weight of the thermoplastics in the UV stabilizer (s) equipped Layers.

Weathering according to the test specification ISO 4892 with the Atlas CI65 Weatherometer have shown that in the case of the aforementioned three-layered Film is sufficient, the base layer (B) and the non-sealable cover layer (C) with UV stabilizers equip, for improved UV stability across from to achieve the state of the art.

weathering tests have shown that the invention UV-stabilized films even with weathering tests after extrapolated 5 to 7 years outdoor use generally no yellowing, no embrittlement, no loss of gloss Surface, no cracking on the surface and have no deterioration in mechanical properties. The sunscreen can already be used by the thermoplastic raw material manufacturer be metered or in the film production in the extruder be dosed.

Prefers is the addition of the light stabilizer via masterbatch technology. Here, the UV additive is first in a carrier material fully dispersed. As a carrier material the thermoplastic itself, e.g. the polyethylene terephthalate or also other polymers that are compatible with the thermoplastic, in question. After dosing to the thermoplastic for film production melt the ingredients of the masterbatch during extrusion and become so dissolved in the thermoplastic.

The Concentration of the UV absorber next to the thermoplastic in the masterbatch is 2.0 to 50.0 wt .-%, preferably 5.0 to 30.0 wt .-%, wherein the Sum of ingredients is always 100 wt .-% is.

Important the masterbatch technology is that the grain size and the bulk weight similar to the masterbatch the grain size and the bulk weight of the thermoplastic, so that a homogeneous distribution and thus a homogeneous UV stabilization can take place.

Furthermore, it was very surprising that even from the films, or the Formkör pern, Regenerat generated can be used again without negatively affecting the yellowness of the film.

The Base layer (B) may additionally contain conventional additives such as stabilizers and / or particles (= filler) included. As stabilizers, for example, phosphorus compounds are advantageous such as phosphoric acid ester used.

typical Particles (filler) for the Base layer (B) are the for the outer layer (C) indicated 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, alumina, Lithium fluoride, calcium, barium, zinc or manganese salts of the used dicarboxylic acids, Carbon black, titanium dioxide, Kaolin or crosslinked polystyrene or acrylate particles.

In a particularly advantageous embodiment contains the base layer no or just the over the regenerated pigment introduced. This will make a slide with very low turbidity receive.

Summarized the film of the invention is characterized especially by a very good stability against UV light, a low Gloss of the film surface (C), by a comparatively low turbidity and a high transparency out. Furthermore it has a good wrapping and processing behavior

Of the Gloss of the film surface (C) (measured at 60 °) is lower than 70. In a preferred embodiment, the gloss is this page is less than 60 and in a particularly preferred embodiment less than 50. This film surface thus provides a particularly high advertising effective character and is therefore particularly suitable as outboard surface with a lamination with steel.

The cloudiness the film is less than 45%. In a preferred embodiment is the cloudiness of the Film less than 40% and in a particularly preferred embodiment less than 35%. The transparency of the film is greater than 80%. In a preferred embodiment is Transparency of the film more than 84% and in a particularly preferred embodiment more than 88%. Due to the comparatively low turbidity and high transparency of the film (compared to a matt monofilm, see comparative example), the film according to the invention can e.g. in counter pressure be printed, the pressure is very easy to recognize.

at The thickness of the cover layer (C) is generally greater than that of the film 0.4 μm and is preferably in the range of 0.5 to 10.0 microns, especially in the range from 0.8 to 9.0 μm and more preferably in the range of 1.0 to 8.0 μm.

at The thickness of the cover layer (A) is generally greater than that of the film 0.4 μm and is preferably in the range of 0.5 to 10.0 microns, especially in the range from 0.8 to 9.0 μm and more preferably in the range of 1.0 to 8.0 μm.

The Total thickness of the polyester film according to the invention can vary within wide limits. It is preferred 5 to 100 μm, in particular 6 to 90 μm, preferably 7 to 80 μm, wherein the layer B is a proportion of preferably 5 to 90% the total thickness has.

production method

The The invention also relates to a process for the preparation of the polyester film according to the invention according to the known from the literature coextrusion.

in the Under this procedure, the procedure is that the individual Layers (A), (B) and (C) of the film corresponding to melts a flat nozzle coextruded, the resulting film for solidification one or more rolls is withdrawn, the film then biaxially stretched, the biaxially stretched film heat-set and optionally corona treated on the surface layer intended for the treatment becomes.

The Biaxial stretching (orientation) generally becomes consecutive carried out, the successive biaxial stretching, at first along (in Machine direction) and then across (perpendicular to the machine direction) is stretched, is preferred.

First, be as usual in the coextrusion process the polymer or the polymer mixtures for the individual layers in an extruder compressed and liquefied, with the optionally as additives provided additives already in the polymer or in the polymer mixture may be included. The melts are then pressed simultaneously through a flat die (slot die), and the extruded multi-layer melt is on or withdrawn several take-off rolls, wherein the melt cools and solidifies into a prefilm.

The Biaxial stretching is generally performed sequentially. there Preferably, the prefilm is first longitudinally (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 to a spatial Orientation (orientation) of the polymer chains. The stretching in the longitudinal direction let yourself with the help of two different according to the desired stretch ratio fast rotating rollers. Used for cross stretching you generally have a corresponding clip frame in which the film on both edges clamped and then at elevated Temperature is drawn to both sides.

The Temperature at which the stretching is carried out can be done in a relative huge Range vary and depends on the desired properties of the film. In general, the longitudinal stretching at a temperature in the range of 80 to 130 ° C and the transverse extent in the range from 90 to 150 ° C performed. The Longitudinal stretching ratio is generally in the range of 2.5: 1 to 6: 1, preferably 3.0: 1 to 5.5: 1. The transverse stretch ratio is generally in the range of 3.0: 1 to 5.0: 1, preferably 3.5: 1 to 4.5: 1.

at the subsequent heat setting is the film over a Duration of about 0.1 to 10 seconds at a temperature of about 150 up to 250 ° C held. Subsequently The film is in the usual Wrapped up way.

Prefers After biaxial stretching, the non-sealable surface of the Film corona- or flame-treated according to one of the known methods. The treatment intensity is generally in the range of over 50 mN / m.

to Setting further desired Properties can add the foil in addition be coated. Typical coatings are adhesion-promoting, antistatic, slip-improving or dehesive layers. It lends itself to these extra Layers over In-line coating by means of aqueous Dispersions before the stretching step in the transverse direction on the film applied.

Advantages of the invention

The UV-stabilized, one-sided sealable and one-sided matte film is characterized by a superb Sealability, a very good manufacturability, a very good processing behavior and by a very good look. The sealable outer layer (A) seals against itself, against the matte topcoat (C) and against substrates made of APET, A / CPET, CPET or metal (e.g., aluminum, steel, painted Steel, chromed or tinned steel). The foil is thus in can be used in many areas.

The Films according to the invention and the articles made from them are suitable because of their excellent feature combinations for a variety of different Applications, for example Interior panels, for Trade fair construction and trade fair products, as displays, for signs, for protective glazing from Machinery and vehicles, in the lighting sector, in shop and shelf construction, as a promotional item or as a laminating medium for the above-mentioned materials.

by virtue of the good UV stability it is still suitable for Outdoor applications e.g. For Greenhouses, im Advertising sector, canopies, Exterior cladding, Covers of materials and thus the protection of metallic surfaces such as steel sheets, applications in the construction sector and illuminated advertising profiles.

Also impressive the film through a promotional effective anti-reflective, matte surface (C) with high transparency. Besides that is in the production the film ensures that the waste material (regenerate) in an amount in the range of up to 60 wt .-%, based on the total weight of the film, again fed to the extrusion can be, without losing the physical properties of the film are significantly negatively affected, especially their optical Appearance.

The Slide is suitable also very good for the use in the flexible packaging and especially there, where their excellent sealing properties and their good processability come to fruition. This is especially their use on high-speed Packaging machines.

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

to Characterization of the raw materials and the films were in the frame the present invention uses the following measurement methods:

Measurement of the mean particle diameter d ₅₀

The determination of the mean particle diameter d ₅₀ was carried out by laser on a Master Sizer (Malvern Instruments, UK) according to the standard method (other measuring devices are eg Horiba LA 500 (Horiba Ltd., Japan) or Helos (Sympatec GmbH, Germany), which is the use the same measuring principle). The samples were placed in a cuvette with water and then placed in the meter. The measuring process is automatic and includes the mathematical determination of the d ₅₀ value. By definition, the d ₅₀ value is determined from the (relative) cumulative particle size distribution curve: the point of intersection of the 50% by weight ordinate value with the cumulative curve gives the desired d ₅₀ value on the abscissa axis (cf. 3 ).

Measurement of the SPAN 98

The determination of the SPAN 98 was carried out with the same measuring device as described in the determination of the mean diameter d ₅₀ . The SPAN 98 is defined as follows:

For the determination of d ₉₈ and d ₁₀ again the cumulative curve of the particle size distribution is used. The point of intersection of the 98% ordinate value with the cumulative curve gives the desired d ₉₈ value on the abscissa axis, and the point of intersection of the 10% ordinate value with the cumulative curve gives the desired d ₁₀ value on the abscissa axis (cf. 4 ).

Sealing seam strength (compared to APET)

To determine the seal seam strength, a film strip (100 mm long x 15 mm wide) is placed on the APET side of a corresponding strip of a menu dish and at the set temperature of 140 ° C, a sealing time of 0.5 s and a sealing pressure of approx. 3 bar (sealing device HSG / BT from Brugger, Germany, double-sided heated sealing jaw) sealed. Corresponding 5 the sealed strips are clamped in the tensile testing machine (eg universal testing machine TC-FR1.OTH.D09 from Zwick, Germany) and the 180 ° seal strength, ie the force required to separate the test strips, with a take-off speed of 200 mm / min and a Test temperature of 23 ° C determined. The seal seam strength is given in N per 15 mm foil strip (eg 2 N / 15 mm).

Determination of minimum sealing temperature (across from APET)

With the sealing device HSG / ET from Brugger become, as before, in the measurement of the seal seam strength described, heat-sealed Samples (sealed seam 15 mm × 100 mm), the film at different temperatures with the help of two heated sealing jaws at a sealing pressure of 3 bar and a sealing time of 0.5 s is sealed. The 180 ° seal strength was measured as in the determination of the seal seam strength. The minimum sealing temperature is the temperature at which a sealed seam strength of at least 0.5 N / 15 mm is reached (= sealing temperature).

Sealing seam strength against itself self (= FIN-seal)

to Determination of the seal seam strength two 15 mm wide film strips were superimposed and at 130 ° C, a sealing time of 0.5 s and a sealing pressure of 2 bar (device: Brugger Type NDS, one side heated sealing jaw) sealed. The seal seam strength was after the T-Peel method at 23 ° C and a take-off speed determined from 200 mm / min = 290 °).

Determination of minimum sealing temperature across from oneself

Heat-sealed samples (sealing seam 20 mm × 100 mm) are produced with the sealing device HSG / ET from Brugger, the film being sealed at different temperatures with the aid of two heated sealing jaws at a sealing pressure of 2 bar and a sealing time of 0.5 s. Test strips of 15 mm width were cut from the sealed samples. The T-seam strength was measured as in the determination of the seal strength. The minimum sealing temperature is the temperature at which a Sealed seam strength of at least 0.5 N / 15 mm is achieved.

cloudiness

The cloudiness is determined according to ASTM D 1003-52.

shine

Of the Gloss is determined according to DIN 67530. The reflector value is measured as an optical parameter for the surface of a Foil. Based on standards ASTM-D 523-78 and ISO 2813 the angle of incidence with 20 ° (for shiny surfaces) or 60 ° (for matt Surfaces) set.

SV value (standard Viscosity)

The standard viscosity SV (DCE) is measured, based on DIN 53726, at 25 ° C. in dichloroacetic acid. The intrinsic viscosity (IV) of polyethylene terephthalate is calculated from the standard viscosity as follows IV = [η] = 6.907 x 10 -4 SV (DCE) + 0.063096 [dl / g]

friction

The Friction was determined according to DIN 53 375. The sliding friction coefficient was Measured 14 days after production.

Weathering (on both sides), UV stability

The UV stability is tested according to the test specification ISO 4892 as follows
Test equipment: Atlas Ci 65 Weatherometer
Test conditions: ISO 4892, ie artificial weathering
Irradiation time: 1000 hours (per page)
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 of samples then again 102 minutes of UV light, etc.

color change

The color change samples after artificial Weathering is measured with a spectrophotometer according to DIN 5033.

ever bigger the numerical deviation from the standard, the greater the color difference. Numerical values of 0.3 are negligible and mean that no significant color change is present.

yellowness

Of the Yellowness G (YID) is the deviation from colorlessness in the direction "yellow" and is in accordance with DIN 6167 measured. Yellow values of <5 are not visually visible.

• +: Das Verhalten der Folie ist einwandfrei. Es wurden z.B. keine Falten und keinen Blasen festgestellt.
• –: Das Verarbeitungsverhalten der Folie ist fehlerbehaftet. Es wurde mindestens einer der folgenden Fehler beobachtet: Falten oder Blasen.

Processing behavior of the film The behavior of the film was assessed visually during lamination on steel sheets.

• +: The behavior of the film is flawless. For example, no wrinkles and no bubbles were detected.
• -: The processing behavior of the film is faulty. At least one of the following errors was observed: wrinkles or blisters.

Tears in the film production

The number of foil breaks per unit of time in production is the same as in the production of foil compared with the prior art and found the percentage deviation

example 1

crisps of polyethylene terephthalate and polyethylene terephthalate containing a UV stabilizer were at a temperature of 150 ° C to a residual moisture of below 100 ppm and fed to the extruder for the base layer (B). Also were chips of polyethylene terephthalate, polyethylene terephthalate containing a UV stabilizer and copolyester containing silica particles dried as a pigment and the extruder for the matt top layer (C) fed.

Besides chips were made from a linear polyester, which consists of a amorphous copolyester with 78 mole% ethylene terephthalate and 22 mole% Ethylene isophthalate (prepared via the transesterification process with Mn as transesterification catalyst, Mn concentration: 100 ppm). The copolyester was at a temperature of 100 ° C to a residual moisture of below 200 ppm dried and the extruder for the sealable topcoat (A) supplied.

The UV stabilizer 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5- (hexyl) -oxyphenol ( ^® Tinuvin 1577) is metered in as a masterbatch. The masterbatch is composed of 20% by weight of Tinuvin 1577 as the active ingredient component and 80% by weight of polyethylene terephthalate. The Tinuvin 1577 is added to the base layer (B) and the matte topcoat (C) in the amounts indicated below via masterbatch technology.

Then, by coextrusion and subsequent stepwise orientation in the longitudinal and transverse directions, a transparent, three-layer film with ABC structure and a total thickness of 25 microns was prepared. The thickness of the respective outer layers is shown in Table 2. Cover layer (A): 100.0% by weight Copolyester with an SV value of 800 Base layer (B): 88.0% by weight Polyethylene terephthalate with an SV value of 800 12.0% by weight UV masterbatch based on polyethylene terephthalate Cover layer (C): 70.0% by weight Copolyester (from 78 mol% terephthalic acid, 22 mol% isophthalic acid and 100 mol% ethylene glycol) and 5 wt .-% silica particles (Sylysia 430 from Fuji / Japan) with a d ₅₀ value of 3.4 microns and a SPAN 98 of 1.6 22.0% by weight Polyethylene terephthalate 4023 from the company KoSa, Germany with an SV value of 800 8.0% by weight UV masterbatch based on polyethylene terephthalate

The production conditions in the individual process steps were:

The Film had the required low gloss, low haze and the good sealing properties. Furthermore, the film can be easily, i.e. without an increased Number of breaks, manufacture. The foil shows the desired handling and the desired one Processing performance. The film structure and the properties achieved thus produced films are shown in Tables 2 and 3.

The Foil in this and in all subsequent examples were after the test specification ISO 4892 on both sides per 1000 hours per page weathered with the Atlas Ci 65 Weatherometer from the company Atlas and then with respect to the mechanical properties, discoloration, surface defects, the cloudiness and the gloss tested.

Example 2

in the Compared to Example 1, the top layer thickness of the sealable layer (A) from 1.5 to 2.0 μm otherwise identical film structure and identical manufacturing method raised. The sealing properties have improved as a result, in particular, the seal seam strength has become significantly larger.

Example 3

in the Compared to Example 1, the top layer thickness of the sealable layer (A) to 2.5 microns and that of the matte layer (C) raised to 2.0 microns. The sealing properties have thereby further improved, in particular, the seal seam strength become much bigger. The degree of matting of the film has tended to improve.

Example 4

As compared with Example 1, the pigmentation of the matte layer (C) has now been changed, and the matte layer (C) cover layer thickness has been increased to 2.0 μm. The degree of matting of the film has improved. Cover layer (C): 80.0% by weight Copolyester (from 78 mol% terephthalic acid, 22 mol% isophthalic acid and 100 mol% ethylene glycol) and 5 wt .-% silica particles (Sylysia 430 from Fuji / Japan) with a d ₅₀ value of 3.4 microns and a SPAN 98 of 1.6 12.0% by weight Polyethylene terephthalate from the company KoSa, Germany with an SV value of 800 and 5 wt .-% silica particles (Sylysia 430 from Fuji / Japan) with a d ₅₀ value of 3.4 microns and a SPAN 98 of 1, 6 8.0% by weight UV masterbatch based on polyethylene terephthalate

Comparative Example 1

Compared to Example 1, the sealable topcoat (A) has now been pigmented as follows: 80.0% by weight Copolyester with an SV value of 800 20.0% by weight Masterbatch of 99 wt .-% copolyester and 1.0 wt .-% Sylobloc 44 H (synthetic SiO ₂ from Grace)

The Winding and the processing properties of the film have become by this measure marginally improved, however, are the sealing properties and the Optics of the film have become significantly worse.

Comparative Example 2

It Example 1 from EP-A-0 035 835 was worked up. The sealing behavior, the appearance, the handling and the processing behavior of the film are worse than in the inventive examples.

Comparative Example 3

It Example 1 from EP-A-1 219 413 A1 was worked up. The sealing behavior, the appearance and the tear-off behavior during the production of the film is much worse than in the examples according to the invention become.

The The most important properties of the films thus produced are in the Tables 2 and 3 summarized below.

Claims (14)

Multilayered, one-sided, matt, one-side sealable, UV-stabilized, biaxially oriented polyester film with a base layer (B), a sealable cover layer (A), which is located on a surface of the base layer B, and a matt cover layer (C), which is on the other surface of the base layer B, characterized in that a) the sealable outer layer (A) contains less than 0.01 wt .-% of external particles (based on the total weight of the outer layer (A)) and b) the matte outer layer ( C) i. a polyester containing from 6 to 30 mol% of isophthalic acid units based on the total amount of acid of the polyester in this layer, and ii. contains a pigment characterized by the following features: the average diameter of the particles (d ₅₀ value) is in the range of 2 to 10 μm, the dispersion of the particle size distribution, expressed by the SPAN 98, is in the range of 1 , 2 to 2, and • the concentration of the particles is in the range of 1.0 to 7.0 wt .-%, based on the total weight of the outer layer (C). Polyester film according to claim 1, characterized that the film is a cloudiness of less than 45%. Polyester film according to claim 1 or 2, characterized the base layer (B) contains a thermoplastic polyester Polyester film according to one or more of claims 1 to 3, characterized in that the polyester of the base layer (B) at least 90 mole% ethylene glycol and terephthalic acid units or ethylene glycol and naphthalene-2,6-dicarboxylic acid units. Polyester film according to one or more of claims 1 to 4, characterized in that as polyester of the base layer (B) Polyethylene terephthalate is used Polyester film according to one or more of claims 1 to 5, characterized in that the sealable cover layer (A) has a Contains copolyester, composed of ethylene terephthalate and ethylene isophthalate units is. Polyester film according to one or more of claims 1 to 6, characterized in that the copolyester of the sealable cover layer (A) 60-95 Mol% ethylene terephthalate and 40-5 mol% ethylene isophthalate units having. Polyester film according to one or more of claims 1 to 7, characterized in that the pigment of the cover layer (C) consists of SiO ₂ particles. Polyester film according to one or more of claims 1 to 8, characterized in that the sealable outer layer (A) no contains added particles. Polyester film according to one or more of claims 1 to 9, characterized in that the cover layer (A) has a thickness of 0.5 to 10 μm having. Polyester film according to one or more of claims 1 to 10, characterized in that the minimum sealing temperature of Covering layer (A) against an APET substrate 140 ° C or less. Polyester film according to one or more of claims 1 to 11, characterized in that the cover layer (A) has a gloss from bigger than 130 (measuring angle 20 °). Process for producing a polyester film according to one or more of Claims 1 to 12, comprising the steps of a) producing a multilayer film by coextrusion, b) biaxially stretching the film and c) thermosetting the stretched film, the polymer for the sealable outer layer (A) containing less than 0.01 wt .-% of particles (based on the total weight of the outer layer (A)) and the polymer for the matte outer layer (C) i. a polyester containing from 6 to 30 mol% of isophthalic acid units based on the total amount of acid of the polyester in this layer, and ii. contains a pigment characterized by the following features: the average diameter of the particles (d ₅₀ value) is in the range of 2 to 10 μm, the dispersion of the particle size distribution, expressed by the SPAN 98, is in the range of 1 , 2 to 2, and • the concentration of the particles is in the range of 1.0 to 7.0 wt .-%, based on the total weight of the outer layer (C). Use of a polyester film after one or several of the claims 1 to 12 as packaging film, laminating film against APET, CPET and Metals, as interior trim, display, promotional items or for greenhouses, canopies and exterior panels.