DE10128711A1 - Label film useful as a top layer for PS, PP, PE, PVC, metal, and tin plate containers, has improved adhesion and subsequent application - Google Patents

Abstract

The biaxially oriented multi-layer coextruded polyolefin film comprising a base layer and at least one inner layer, which are simultaneously extruded through a multilayer nozzle and biaxially stretched together. The inner top layer comprises at least 70 wt.% of co- or terpolymer, which is obtained from an olefin and an unsaturated carboxylic acid or their esters or anhydrides, and contains at most 30 wt.% of additive. Independent claims are included for: (1) a label film applied to a container in an in-mold or thermo labeling process, and the inner top layer is moved towards the container and forms the adjacent surface of the visible side; (2) a label container; (3) a multi-layer laminate in which the label film is laminated to a second film of thermoplastic polymer or a paper, wood, or metal substrate; (4) a biaxially oriented multi-layer polyolefin film as described above which can be applied by thermo labeling as a removeable protective film to tin plate, wood, glass, or metal, preferably aluminum; (5) preparation of a polyolefin film by coextrusion, in which the individual layers of the film are melted and coextruded through a flat nozzle, the film obtained is strengthened by drawing with one or more rollers, and the multi-layer film is stretched, and heat fixed. The top layer of the film comprises at least 70 wt.% of a co- or terpolymer etc. as described above. The film is stretched longitudinally on heated rollers at 10 deg C above or below the melting point of the Co-or terpolymer. The inner top layer contains 70-99.5 wt.% of co- or terpolymer. The copolymer contains more than 65 wt.% olefin units, preferably ethylene units and at most 35 wt.% unsaturated monocarboxylic acid units or their esters, preferably (meth)acrylic acid or their esters. The terpolymer comprises (wt.%): (a) olefin, preferably ethylene (65-96), (b) unsaturated carboxylic acids or their esters, preferably acrylic acid ester, preferably acrylic acid methyl-, ethyl-, n-propyl-, i-propyl-, n-butyl-, i-butyl-, sec-butyl-, or t-butyl ester (3-34), (c) various unsaturated mono- or dicarboxylic acid acids or their esters or anhydrides, preferably maleic acid anhydride or glycidyl methacrylate, in quantity 1-10 wt.% relative to (b). The inner top layer contains an antiblock agent (1-5), a lubricant, preferably erucic acid amide and/or a polydimethylsiloxane. The inner top layer contains a mixture of two or more additives, preferably wax (1-10) and HDPE (1-20), and is corona, plasma, or flame treated. The film on the side opposite the inner top layer of the base layer has an extra outer top layer which comprises a co- and/or terpolymer. The surface of the outer top layer is corona, plasma, or flame treated. The antiblock agent is silicon dioxide. The top layer film thickness is 15-150, preferably 25-90, and the base layer 40-60% of the total thickness of the label film. The base layer comprises propylene polymers, preferably propylene homopolymers, is opache, and contains vacuole initiated filler (-.5-30) and optionally pigment (1-10), contains lubricant and/or antistatic, preferably tertiary aliphatic amine.

Description

The invention relates to the use of a film made of thermoplastic Plastics for labels with improved adhesion to various materials, the labels themselves, as well as methods of making the labels.

Food and other packaged goods are often stored in stiff-walled containers packed with a label according to the "In-Mold Labeling "or" IML process ". This is usually done by one Robot, a label placed in the open form so that the printed (outer Side) of the label on the mold wall, the unprinted (inner side) to the forming container is facing. A smooth, wrinkle-free application of the label in the shape is achieved, for example, by a vacuum that adheres to fine Vent holes are created, with the holes largely from the label be closed. Or electrostatic forces between the electrostatic loaded label and the grounded shape ensure that the Label.

The advantage of the IML process is that the print quality is separate produced labels is much better than the direct printing on the Container. The application of the label when forming the container is inexpensive and effective. You don't need any glue, no coated carrier foils or -paper and thus saves the disposal of waste and residues. The in-mold Labeling processes can be carried out using various manufacturing processes for containers combine. Variants of the IML process were e.g. B. for injection molding, Thin-wall injection molding, blow molding and deep drawing or thermoforming and that Injection stretch blow molding of containers proposed or already developed.

Furthermore, there are methods for labeling containers after their manufacture  or known after filling, such as. B. the all-round labeling, patch Labeling, self-adhesive labels and "thermal labeling".

Thermolabeling includes all processes in which a label under the influence of Heat is applied to a container. For example, it can already molded containers heated in a suitable process and the label with pressure or pressed against the container wall with the help of brushes or rollers be that it is then firmly connected to the container.

There is one in both in-mold labeling and thermal labeling bubble-free application of the label an important and at the same time problematic Requirement. To achieve this, the inner, i.e. H. the the container facing surface of the label film structured or roughened so that the Escaping air from the gap between the label and the container wall is facilitated.

In the case of simple label forms, the label is usually fed in and rolled up the machine in which the container is shaped (cut in place). This method is particularly useful for simple, e.g. B. rectangular Cut the labels to how they are used in particular in the wrap-around labeling (WAL) and patch labeling of essentially cylindrical containers and Bottles are used.

With more complex outlines, the label is often pre-cut, in Magazines stacked, later separated from the stack on the labeling machine and in the shape inserted (cut & stack method). The labels are z. B. initially using the so-called sheetfed offset process or other suitable Process printed and immediately after printing to its final Cut shape. Both the unprinted and the printed sheets and In the individual procedural steps, sheet cutting, printing,  Have label cutting and feeding for labeling processed without any problems. The sheet and label are stacked and unstacked. The Slides easily against each other and they must not become electrostatic charge. In addition to equipping the label film with lubricants and antistatic agents a corresponding structuring of the film surface is therefore necessary.

Different materials such as e.g. B. Polypropylene (PP), high or low density polyethylene (HD-PE or LD-PE or LLD-PE, polystyrene (PS), polyvinyl chloride (PVC), polyethylene terephthalate PET; Polycarbonate (PC) and in some cases also mixtures of such polymers used. This results in different requirements for the Label materials with regard to strength, extensibility, rigidity, gloss / mattness and adhesion to the container wall. Become biaxial for cost reasons oriented polypropylene films (boPP films) are preferably used, these Applications currently limited to polypropylene and polyethylene containers are.

The conventional boPP labels stick even at elevated temperatures the other container materials mentioned bad. It is not possible to use labels made of boPP film on containers made of PET, PS, PC or PVC using in-mold or Apply thermal labeling process. In particular, it has so far not been possible to use boPP foils in the injection molding IML process on polystyrene. It is also not possible to label foils made of boPP foils in the thermal label Use procedures on PET bottles. Appropriate adhesives must be used here The label can be attached. Despite extensive attempts different container materials and different label materials with the To combine various known labeling methods, the choice of successful combinations very limited. The direct use of boPP films in the IML or thermolabeling process for labeling containers that  are not made of PP or PE until now. For the liability of boPP labels on PS, PET, PC, PVC etc. are adhesives, coatings, varnishes or similar aids are required, which subsequently, d. H. after manufacturing the film, must be applied in an additional processing step.

On the one hand, this makes the label more expensive and sometimes has an adverse effect on the label other performance characteristics.

From the British application GB 2 223 446 a boPP film is known which consists of there is at least two layers, the comparatively thinner layer consisting of a blend of a material that has a low seal strength against PVDC and a material consisting of a copolymer of an alkene and an unsaturated monobasic acid or its ester. In preferred Embodiments come as materials with a low seal strength against high and low density PVDC polyethylenes as copolymers those of ethylene with acrylic acid esters, these copolymers in particular preferred embodiments of unsaturated dibasic acids or their Anhydrides such as B. maleic anhydride as further monomers. Corresponding copolymers or terpolymers have been described in EP 0 065 898.

During the reworking of the British application GB 2 223 446 it was found that the method described there using the specified there Formulations to a high degree and intolerable for industrial practice Deposits on the heating and stretching rollers of the longitudinal drafting unit sequential BOPP plant leads. Variations in the context of the disclosed teaching provided little or no benefit in terms of quantity and Speed of the built-up roller covering or others Performance characteristics have been adversely affected.

The object of the present invention was a biaxially oriented  To provide polyolefin film that is inexpensive and as a label film can be used in many ways. The film should in particular by means of IML or Thermolabeling process on containers made of different materials, such as. B. PP, PE PET, PS, PC, PVC etc. must be applied and have good adhesion. Of course, it is necessary for the film to settle without the formation of deposits can produce the rollers of the longitudinal drafting system. In addition, the other important usage properties and the look of the film, or the labels produced therefrom are not adversely affected. In particular, should the film can be printed on one side and can be stacked well in the processing process and to be unstacked.

This problem is solved by using a multilayer biaxial oriented polyolefin film consisting of a base layer and at least one inner layer Cover layer, wherein this inner cover layer at least 70 wt .-% of a Co or Terpolymers, which at least from olefin and unsaturated carboxylic acid or whose esters or their anhydrides are built up, and at most 30% by weight contains an additive, the details in wt .-% each referring to the Obtain the weight of the first cover layer. The subclaims give preferred Embodiments of the invention.

In the context of the present invention, it has surprisingly been found that the inner cover layer of the copolymers and terpolymers I mentioned excellent adhesion to a wide variety of polymer materials which are usually formed into containers. This is the first time Material will be made available, which surprisingly Labeling of containers made of PP or PE and PVC or PET or PC or PS equally successful using thermolabelling or the in-mold process can be used. It was found that a small amount of one Additive in the inner top layer made of co- or terpolymer I.  Roller deposits effectively prevented in the manufacture of the film and at the same time the desired good and diverse adhesive properties of the film when used as an IML or thermolabelling label. In particular, it was found that a cover layer, which can only be or terpolymer I is built up in such a way on the production of the film Rolls glued or deposits that handling the material in the Manufacturing process of the film is almost impossible.

Surprisingly, the film shows when used as a label in the InMould and thermal labeling processes have excellent adhesive properties, not only compared to containers made of PP and PE. The film can also be used as a label Excellent application on containers made of PS, PVC, PC and PET without additional adhesives, varnishes, coatings or other auxiliary materials are required. When used according to the invention as a label film in the IML or Thermolabeling process will have very good adhesion between the label and Container found. This is the first time that a material has been made available which in a previously unattainable width for different Container materials can be used. This also has significant logistical Benefits.

Due to these special adhesive properties, this film can not only be used for Labeling of containers made of PP, PE, PS, PVC, PC and PET are used, but also in a special application as a lidding film for containers PP, PE, PS, PVC, PC and PET. Containers of any shape come as containers in question, such as B. cups, trays, moldings, etc. It was found that the inner cover layer has a very good adhesion even as a cover and the The container is well sealed and thus reliably protects against contamination. At the same time, the film can be removed from the container without residue if that Packaged goods should be removed. Known lidding films according to the state of the  Technology often leave rag-like ones after being removed from the container white cuticles on the edge, or in the sealing or embossing area of the container the film was welded on. These film residues then on the edge of the container hanging may interfere with the removal of the packaged goods Consumers are not easily identified and are therefore not acceptable. Another advantage was found that the application of the Cover film at temperatures of <100 ° C, preferably 70 to <100 ° C can take place and already achieved good adhesion at these temperatures becomes. As a result, the container edge and / or the intermediate webs remain dimensionally stable.

Furthermore, it was found that the film with its inner cover layer too excellent adhesive properties to surfaces made of paper, wood, Metal, for example aluminum or tinplate. Based on these Adhesive properties can make the film advantageous for other applications be used.

The film can be used for lamination and lamination with other flat surfaces Substrates are used. For example, the film with your inner surface excellent against paper, aluminum and others Laminate thermoplastic films. Furthermore, the slide shows on the Surface of the inner cover layer against increased adhesion Cold seal adhesives, printing inks and various coatings, which after the Production of the film can be applied. In another application it shows the film has improved adhesion during metallization Vacuum deposition.

For these good adhesive properties, the structure and composition of the inner cover layer of the film essential. This inner top layer is in the Label facing the container and forms the connection between the container  and label. For appropriate applications as a cover film is when applying of the lid, the inner cover layer faces the container and forms the Connection between the lid film and the container.

For the purposes of the present invention, the inner cover layer is that Cover layer, which faces the container when labeling and when Labeling forms the connection between the container and the label. construction and composition of the inner cover layer are essential for the good and diverse adhesive properties of the label. It was found that the surface the inner cover layer has an increased surface roughness, which when Labeling process facilitates destacking and a bubble-free application supported. Surprisingly, the good and varied Adhesion properties are not affected by this surface roughness.

The inner cover layer contains a Co or as essential components of the invention Terpolymer I from an olefin and an unsaturated carboxylic acid or their Esters or their anhydrides and an additive. If applicable, the inner top layer additionally antiblocking agents. Generally the inner contains Top layer at least 70% by weight, preferably 80 to 99.5% by weight, in particular 85 to 99% by weight of the copolymer or terpolymer I and at most 30 % By weight, preferably 0.5 to 20% by weight, in particular 1 to 15% by weight of the Additive, each based on the weight of the inner top layer.

Suitable copolymers or terpolymers I are made from olefins and unsaturated Carboxylic acids or their esters or their anhydrides built up as monomers. Olefins are, for example, ethylene, propylene or butene-1, possibly also higher Homologues such as B. witches or octene. Include unsaturated carboxylic acids unsaturated mono- and dicarboxylic acids and their esters or anhydrides. As Unsaturated carboxylic acids are acrylic acid or methacrylic acid and their esters  prefers. Basically, the copolymer or terpolymer I can be made from various Olefins and various unsaturated carboxylic acids or their Ester / anhydrides. Copolymers I of are particularly advantageous Ethylene and acrylic acid esters.

Terpolymers I are generally composed of three different monomers (a), (b) and (c) built. Monomers (a) include the olefins mentioned above, the monomers (b) are unsaturated carboxylic acids or their esters, monomers (c) are carboxylic acid esters or carboxylic acid anhydrides other than (b). As Monomer (c) are unsaturated monocarboxylic acid esters, for example Glycidyl methacrylate, or unsaturated dicarboxylic acids or their anhydride, such as for example maleic acid or maleic anhydride is preferred. Especially Terpolymers of (a) ethylene, (b) acrylic acid or methacrylic acid are advantageous or their esters and (c) glycidyl methacrylate or maleic anhydride.

The esters of the unsaturated carboxylic acids described are derived from one or more lower alcohols. For example, methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl or tert-butyl esters.

The composition of the copolymers or terpolymers I from the respective monomers can vary within the limits described below. Copolymers I generally contain at least 60% by weight, preferably 70 to 97% by weight of olefin, preferably ethylene and at most 40% by weight, preferably 3 to 30% by weight of unsaturated carboxylic acids or their esters, preferably acrylic acid or methacrylic acid or their esters. Terpolymers I generally contain

• a) 65 to 96 wt .-%, preferably 72 to 93 wt .-% olefin, preferably Ethylene and
• b) 3 to 34 wt .-%, preferably 5 to 26 wt .-% unsaturated carboxylic acids  or their esters, preferably acrylic acid or methacrylic acid or their Esters and
• c) 1 to 10% by weight, preferably 2 to 8% by weight, different from (b) unsaturated mono- or dicarboxylic acids or their esters or their Anhydride, preferably maleic anhydride or glycidyl methacrylate.

The copolymers or terpolymers described above (the inner cover layer generally have a melting point of 40 to 120 ° C, preferably 60 to 100 ° C. The Vicatpunkt (according to DIN 53 460) is preferably in the range from 30 to 90 ° C. The melt index is generally 0.1 to 20 g / 10 min (190 ° C, 21.6 N), preferably 0.1 to 15 g / 10 min.

The inner cover layer contains a further essential component Additive in an amount of 1 to 30 wt .-% based on the weight of the inner cover layer, preferably a wax, preferably polyethylene waxes or paraffins. Polyethylene waxes are low molecular weight polymers that are used in are essentially made up of ethylene units and are partially or highly crystalline. The Polymer chains from the ethylene units are elongated molecules that can be branched, with shorter side chains predominating. In general are polyethylene waxes by direct polymerization of ethylene, optionally using regulators, or by depolymerizing Polyethylenes made with higher molecular weights. Preferably they have Polyethylene waxes have an average molecular weight Mn (number average) of 200 to 5000, preferably from 400 to 2000, particularly preferably 400 to 1000 and preferably a molecular weight distribution (polydispersity) Mw / Mn of below 3, preferably 1 to 2. The melting point is generally in the range of 70 up to 150 ° C, preferably 80 to 100 ° C.

Paraffins include macrocrystalline paraffins (paraffin waxes) and microcrystalline  Paraffins (micro waxes). The macrocrystalline paraffins are made from the Vacuum distillate fractions obtained when processing lubricating oils. The microcrystalline paraffins come from the residues of vacuum distillation and the sediments of paraffinic crude oils (excreted paraffins). The Macrocrystalline paraffins consist predominantly of n-paraffins, which are additional Depending on the degree of refining, iso-paraffins, naphthenes and alkyl aromatics are included. The microcrystalline paraffins consist of a mixture of hydrocarbons, which are predominantly solid at room temperature. Unlike the macrocrystalline Paraffins are predominantly iso-paraffins and naphthenic paraffins. The microcrystalline paraffins are characterized by the presence of crystallization-inhibiting, highly branched iso-paraffins and naphthenes. For the purposes of the invention, paraffins with a melting point of 60 to 100 ° C, preferably 60 to 85 ° C particularly suitable.

In a further embodiment, the inner cover layer as an additive or contain several other components that the deposits in the Foil production in the same way as the wax prevents or prevents. The The proportion of such additives is generally between 2 and 30% by weight. preferably 3 to 20% by weight, in particular 3 to 10% by weight, the Proportion of co- or terpolymer I in the composition of the inner cover layer reduced accordingly. Suitable additives of this type are polyolefins, Polystyrene, polyester, polyamides, hydrocarbon resins.

Particularly suitable polyolefins are those without carboxylic acid monomers. Particularly preferred are polyolefins, which are referred to below as co- and Terpolymers II are described in connection with the outer cover layer, especially propylene polymers or polyethylenes. Suitable polyethylenes are both linear and branched polyethylenes, for example MDPE, VLDPE, LLDPE, LDPE or HDPE.  

As hydrocarbon resins are natural or synthetic resins with one Softening point of 80-180 ° C, such as B. hydrocarbon resins, ketone resins, Rosin, damar resins, polyamide resins and aliphatic and aromatic Suitable hydrocarbon resins.

With in-mold or thermal labeling, it is for a bubble-free application of the Labels particularly desirable that the inner surface of the label sheet to facilitate the escape of air from the gap between the label and Container wall is structured accordingly. It was found that the Mixing of the copolymers and terpolymers I with polyethylenes as an additive to a rough surface of the inner cover layer, which is beneficial to the "Venting" affects labeling. Such PE-containing compositions The inner cover layer are therefore applied in terms of the appearance Label particularly advantageous.

If appropriate, the inner cover layer can also contain mixtures of the above mentioned additives contain, in particular mixtures of wax and Polyethylene are preferred. Combinations of 1-10 wt .-% wax and 1-10% by weight of polyolefin, in particular copolymers II or polyethylenes (each based on the weight of the top layer) with regard to the deposits particularly advantageous in film production, without the adhesive properties of Diminish etiquette.

In addition to the usual label applications, the surface protection from Commodities play an important role. On scratch-sensitive and light fragile materials such as B. glass, becomes a protective film for transport applied, which can be easily removed later. There is some Adhesion of the film to the material to be protected is required  the protective film does not fall off prematurely. At the same time, liability is not allowed be too large to allow trace-free removal. It was found, that for these applications, embodiments with copolymer as an additive, in particular propylene copolymer, such as propylene-ethylene copolymers with a C2 content of 2 to 10 wt .-% are particularly advantageous, wherein for this purpose the content of copolymer up to 50 wt .-%, based on the Weight of the top layer, can be increased.

The inner cover layer can additionally contain conventional additives such as neutralizing agents, Stabilizers, antistatic agents, antiblocking agents and / or lubricants in each effective Amounts included. The following data in% by weight relate in each case on the weight of the inner cover layer. In particular, embodiments are preferred, which additionally contain antiblocking agents in the inner cover layer. It it was found that the antiblocking agent to reduce deposits (pick off) contributes to the manufacture of the film.

Suitable antiblocking agents are inorganic additives such as silicon dioxide, Calcium carbonate, magnesium silicate, aluminum silicate, calcium phosphate and the like and / or incompatible organic polymers such as polyamides, Polyesters, polycarbonates and the like or cross-linked polymers such as cross-linked Polymethyl methacrylate or cross-linked silicone oils. Silicon dioxide and Calcium carbonate is preferred. The average particle size is between 1 and 6 µm, especially 2 and 5 µm. The effective amount of antiblocking agent is Range from 0.1 to 5% by weight, preferably 0.5 to 3% by weight, in particular 0.8 up to 2% by weight.

Lubricants are higher aliphatic acid amides, higher aliphatic acid esters and metal soaps as well as polydimethylsiloxanes. The effective amount of lubricant is in the range from 0.01 to 3% by weight, preferably 0.02 to 1% by weight, based on the inner cover layer. The addition of 0.01 to 0.3% by weight of aliphatic acid amides, such as erucic acid amide or 0.02 to 0.5% by weight of polydimethylsiloxanes, in particular polydimethylsiloxanes with a viscosity of 5,000 to 1,000,000 mm, is particularly suitable ² / s.

In a preferred embodiment, the surface of the inner cover layer Corona, plasma or flame treated. It has been found that such Surface treatment, especially the corona treatment, the adhesive strength of the inner cover layer compared to the different polymer materials improved.

The thickness of the inner cover layer is generally greater than 0.3 μm and lies preferably in the range from 0.5 to 5 μm, in particular 1 to 3 μm.

According to the invention, films which are applied to a container with the inner cover layer described above in the IML process or by the thermolabelling process have very good adhesive strengths not only with respect to PP and PE containers. The adhesive strength to PVC, PS and PET containers is also excellent. When used in the thermolabeling process, an adhesive strength of <0.5 N / 15 mm, generally <1, is achieved at temperatures of 130 ° C and at a sealing pressure of 10 N / cm ² and with a contact time of 0.5 sec. 0 N / 15 mm achieved.

The inner cover layer described above with the invention Composition can be advantageous on transparent or opaque base layers be applied. "Opaque film" means in the sense of the present invention an opaque film whose light transmission (ASTM-D 1003-77) at most 70%, preferably at most 50%.

For transparent embodiments, the base layer of the film contains generally at least 85% by weight, preferably 90 to <100% by weight, in particular 95 to 99% by weight, in each case based on the base layer, of one  Polyolefin. Polyolefins are, for example, polyethylenes, polypropylenes, Polybutylenes or copolymers of olefins with two to eight carbon atoms, among which polyethylenes and polypropylenes are preferred.

Generally the propylene polymer contains at least 90% by weight, preferably 94 to 100% by weight, in particular 98 to <100% by weight, propylene. The corresponding comonomer content of at most 10% by weight or 0 to 6% by weight or 0 to 2% by weight, if present, generally consists of ethylene. The Figures in% by weight relate to the propylene polymer.

Isotactic propylene homopolymers having a melting point of 140 to 170 ° C., preferably 150 to 165 ° C., and a melt flow index (measurement DIN 53 735 at 21.6 N load and 230 ° C.) of 1.0 to 10 g / 10 are preferred minute preferably from 1.5 to 6.5 g / 10 min. The n-heptane-soluble fraction of the polymer is generally 0.5 to 10% by weight, preferably 2 to 5% by weight, based on the starting polymer. The molecular weight distribution of the propylene polymer can vary. The ratio of the weight average M _w to the number average M _n is generally between 1 and 15, preferably 2 to 10, very particularly preferably 2 to 6. Such a narrow molecular weight distribution of the propylene homopolymer of the base layer can be achieved, for example, by its peroxidic degradation or by production of polypropylene using suitable metallocene catalysts.

In a preferred embodiment, the base layer is by adding Fillers opaque. Generally, the base layer in this embodiment contains at least 70% by weight, preferably 75 to 99% by weight, in particular 80 to 98% by weight, based in each case on the weight of the base layer, of the above described polyolefins or propylene polymers, which also Propylene homopolymers described are preferred.  

The opaque base layer contains fillers in a maximum amount of 30% by weight, preferably 1 to 25 wt .-%, in particular 2 to 20 wt .-%, based on the Weight of the base layer. Fillers are in the sense of the present invention Pigments and / or vacuole-initiating particles.

For the purposes of the present invention, pigments are incompatible particles which essentially do not lead to the formation of vacuoles when the film is stretched. The coloring effect of the pigments is caused by the particles themselves. "Pigments" generally have an average particle diameter of 0.01 to at most 1 µm, preferably 0.01 to 0.7 µm, in particular 0.01 to 0.4 µm. Pigments include both so-called "white pigments", which white the films color, as well as "colored pigments", which give the film a colorful or black Give color. Common pigments are materials such as B. alumina, Aluminum sulfate, barium sulfate, calcium carbonate, magnesium carbonate, silicates such as Aluminum silicate (kaolin clay) and magnesium silicate (talc), silicon dioxide and Titanium dioxide, including white pigments such as calcium carbonate, silicon dioxide, Titanium dioxide and barium sulfate are preferably used.

The titanium dioxide particles generally consist of at least 95% by weight of rutile and are preferably used with a coating of inorganic oxides and / or of organic compounds with polar and nonpolar groups. Such coatings of TiO ₂ are known in the prior art.

For the purposes of the present invention, "vacuole-initiating fillers" are solid Particles which are incompatible with the polymer matrix and when stretching the Foils lead to the formation of vacuole-like cavities, whereby size, type and Number of vacuoles on the size and quantity of solid particles and the Stretch conditions such as stretch ratio and stretch temperature are dependent. The  Vacuoles reduce the density and give the films a characteristic mother-of-pearl, opaque appearance, which is due to light scattering on the Interfaces "vacuole / polymer matrix" are created. The light scatter on the fixed Particles themselves generally contribute relatively little to the opacity of the film at. As a rule, the vacuole fillers have a minimum size of 1 µm to achieve an effective, i.e. H. lead opacifying amount of vacuoles. In general, the average particle diameter of the particles is 1 to 6 μm, preferably 1.5 to 5 µm. The chemical character of the particles plays a role subordinate role if there is an intolerance.

Usual vacuole-initiating fillers are inorganic and / or organic, with Polypropylene incompatible materials such as aluminum oxide, aluminum sulfate, Barium sulfate, calcium carbonate, magnesium carbonate, silicates such as aluminum silicate (Kaolin clay) and magnesium silicate (talc) and silicon dioxide, including Calcium carbonate and silicon dioxide are preferably used. As organic Fillers come with the polymers that are commonly used Base layer incompatible polymers, in particular those such as HDPE, Copolymers of cyclic olefins such as norbornene or tetracyclododecene with Ethylene or propene, polyester, polystyrene, polyamide, halogenated organic Polymers, with polyesters such as polybutylene terephthalates being preferred are. "Incompatible materials or incompatible polymers" in the sense of The present invention means that the material or the polymer in the film is present as a separate particle or as a separate phase.

The opaque base layer contains pigments in an amount of 0.5 to 10% by weight, preferably 1 to 8% by weight, in particular 1 to 5% by weight. vacuole Fillers are in an amount of 0.5 to 30% by weight, preferably 1 to 15% by weight, contain in particular 1 to 10 wt .-%. The information relates to the Weight of the base layer.  

Depending on the composition of the base layer, the density of the film can vary in a range from 0.4 to 1.1 g / cm ³ . Vacuoles contribute to lowering the density, whereas pigments, such as. B. TiO ₂ increases the density of the film due to its higher specific weight. The density of the film is preferably 0.5 to 0.95 g / cm ³ .

In addition, the base layer, both in a transparent and in a opaque embodiment conventional additives such as neutralizing agents, stabilizers, Contain antistatic agents and / or lubricants in effective amounts. The The following data in% by weight relate to the weight of the Base layer.

Preferred antistatic agents are glycerol monostearates, alkali-alkanesulfonates, polyether-modified, ie ethoxylated and / or propoxylated polydiorganosiloxanes (polydialkylsiloxanes, polyalkylphenylsiloxanes and the like) and / or the essentially straight-chain and saturated aliphatic, tertiary amines having an aliphatic with 20 to 20 bis with the aliphatic ω-Hydroxy- (C ₁ -C ₄ ) -alkyl groups are substituted, N, N-bis (2-hydroxyethyl) alkylamines having 10 to 20 carbon atoms, preferably 12 to 18 carbon atoms, being particularly suitable in the alkyl radical. The effective amount of antistatic is in the range of 0.05 to 0.5% by weight.

Lubricants are higher aliphatic acid amides, higher aliphatic acid esters, waxes and metal soaps as well as polydimethylsiloxanes. The effective amount of lubricant is in the range of 0.01 to 3% by weight, preferably 0.02 to 1% by weight. The addition of higher aliphatic acid amides in the range from 0.01 to 0.25% by weight in the base layer is particularly suitable. A particularly suitable aliphatic acid amide are erucic acid amide and stearylamide. The addition of polydimethylsiloxanes in the range from 0.02 to 2.0% by weight is preferred, in particular polydimethylsiloxanes with a viscosity of 5,000 to 1,000,000 mm ² / s.

The usual stabilizing compounds for Ethylene, propylene and other α-olefin polymers can be used. their The amount added is between 0.05 and 2% by weight. Pheno are particularly suitable lical and phosphitic stabilizers such as Tris 2,6-dimethylphenyl phosphite. Phenolic stabilizers with a molecular weight of more than 500 g / mol preferred, especially tris-2,6-dimethylphenyl phosphite, pentaerythrityl tetrakis 3- (3,5-di-tertiary-butyl-4-hydroxyphenyl) propionate or 1,3,5-trimethyl-2,4,6- tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene. This will be phenolic Stabilizers alone in an amount of 0.1 to 0.6 wt .-%, in particular 0.1 to 0.3% by weight, phenolic and phosphitic stabilizers in a ratio of 1: 4 to 2: 1 and in a total amount of 0.1 to 0.4 wt .-%, in particular 0.1 to 0.25 wt .-% used.

Neutralizing agents are preferably dihydrotalcite, calcium stearate and / or calcium carbonate with an average particle size of at most 0.7 μm, an absolute particle size of less than 10 μm and a specific surface area of at least 40 m ² / g. Generally 0.02 to 0.1% by weight is added.

For two-layer designs that only have an inner cover layer , it is preferred that the outer surface of the base layer by means of Corona, plasma or flame is surface treated.

The polyolefin film according to the invention preferably has a second, outer Top layer, which adheres well to conventional printing inks, Glues, as well as coatings and / or varnishes shows. This outer top layer  the film is preferably on the opposite surface of the base layer applied and is called "outer cover layer" below. For further It is improving the adhesion of printing inks, adhesives and coatings preferably a corona, plasma or flame treatment of the surface of the perform outer cover layer.

The outer cover layer is generally made from polymers of olefins with 2 to 10 Carbon atoms built up. The outer cover layer generally contains 95 up to 100 wt .-% polyolefin, preferably 98 to <100 wt .-% polyolefin, each based on the weight of the cover layers.

Examples of suitable olefinic polymers of the cover layers are propylene homopolymers, copolymers or terpolymers II made of ethylene-propylene and / or butylene units or mixtures of the polymers mentioned. These copolymers or terpolymers II contain no carboxylic acid monomers (or esters thereof). They are polyolefins. Among these are preferred polymers
statistical ethylene-propylene copolymers with an ethylene content of 1 to 10% by weight, preferably 2.5 to 8% by weight, or
statistical propylene-butylene-1 copolymers with a butylene content of 2 to 25% by weight, preferably 4 to 20% by weight, or
statistical ethylene-propylene-butylene-1 terpolymers with an ethylene content of 1 to 10% by weight and a butylene-1 content of 2 to 20% by weight, or
a mixture or blend of ethylene-propylene-butylene-1 terpolymers and propylene-butylene-1 copolymers with an ethylene content of 0.1 to 7% by weight and a propylene content of 50 to 90% by weight and a butylene -1 content of 10 to 40 wt .-%. The percentages by weight relate to the weight of the polymer.

The co- described above used in the outer cover layer  and / or terpolymers II generally have a melt flow index of 1.5 up to 30 g / 10 min, preferably from 3 to 15 g / 10 min. The melting point is in Range from 120 to 145 ° C. The blend of Co and Terpolymer II has a melt flow index of 5 to 9 g / 10 min and one Melting point from 120 to 150 ° C. All of the above Melt flow indices are measured at 230 ° C and a force of 21.6 N (DIN 53 735) measured. If necessary, all of the above can be described Cover layer polymers have been degraded peroxidically or also thermooxidatively, wherein the degradation factor generally in a range from 1 to 15, preferably 1 to 8 lies.

If necessary, the outer cover layers can be those described above Additives such as antistatic agents, neutralizing agents, lubricants and / or stabilizers, as well as additional antiblocking agents if necessary. The information in % By weight then relate accordingly to the weight of the cover layer.

Suitable antiblocking agents are already in connection with the inner one Top layer described. These antiblocking agents are also for the outside Suitable top layer. The preferred amount of antiblocking agent is for the outside Cover layer in the range of 0.1 to 2 wt .-%, preferably 0.1 to 0.8 wt .-%.

The thickness of the outer cover layer is generally greater than 0.1 μm and lies preferably in the range from 0.1 to 5 μm, in particular 0.3 to 2 μm.

In a particularly preferred embodiment, the surface of the outer Top layer treated with corona, plasma or flame. This treatment serves the film surface for subsequent decoration and printing prepare, d. H. the wettability with and adhesion of printing inks and to ensure other decorative means.  

The film according to the invention comprises at least the one described above Base layer and the inner cover layer, made of co- or terpolymer I and Additive. If necessary, there is a second, on the opposite surface outer cover layer applied. If necessary, can also be one-sided or intermediate layers on both sides between the base and the deck (s) layer (s) must be present.

The intermediate layers can be made for the base layer or for the Outer layers described olefinic polymers, preferably propylene polymeric structure. The intermediate layers can be used for the common additives such as antistatic agents described in individual layers, Contain neutralizing agents, lubricants and / or stabilizers. In another Embodiment can be that intermediate layer which between the Base layer and the inner cover layer is arranged, also an additive as described above for the inner cover layer. As Additives are also the described polyolefins, polystyrene, polyester, Polyamides, hydrocarbon and wax preferred. The additive content in the intermediate layer is at most 30% by weight and is preferably in the range from 0.5 to 20% by weight, based in each case on the weight of the intermediate layer. The The thickness of this intermediate layer is greater than 0.5 μm and is preferably in the Range from 0.6 to 6 µm, especially 1 to 4 µm.

Among the possible suitable additives are higher aliphatic acid amides higher aliphatic acid esters, e.g. B. erucic acid amide and / or polysiloxane, such as Polydimethylsiloxanes are particularly suitable, these additives being customary or slightly increased amounts can also be used. For example, up to 5% by weight of ESA or PDMS can be incorporated into the intermediate layer.  

If necessary, the intermediate layer can additionally be used for the cover layers described antiblocking agents contain in addition to the surface roughness contribute.

The intermediate layer, which in a preferred embodiment can be applied between the outer cover layer and the base layer (hereinafter the outer intermediate layer), contributes to a high gloss on the outside of the label, in particular unfilled outer intermediate layers made of propylene homopolymer. For embodiments in which a white or opaque appearance (high opacity) of the label is desired, the outer intermediate layer contains vacuole-initiating fillers and / or pigments, in particular TiO ₂ . The thickness of this outer intermediate layer is greater than 0.3 μm and is preferably in the range from 1.0 to 15 μm, in particular 1.5 to 10 μm.

The total thickness of the label film according to the invention can continue within Limits vary and depend on the intended use. It is preferably 15 to 150 μm, in particular 20 to 100 μm, preferably 25 to 90 µm. The base layer makes up about 40 to 99% of the total film thickness.

The invention further relates to a method for producing the fiction, ge moderate polyolefin film according to the known coextrusion process. in the As part of this process, the individual layers of the film corresponding melts simultaneously and together through a coextru flat die diert, the film thus obtained stripped on one or more rollers for solidification gene, the multilayer film then stretched (oriented), the stretched film heat-set and, if necessary, on the treatment Surface layer treated with plasma, corona or flame.

Biaxial stretching (orientation) is carried out sequentially or simultaneously. The  sequential stretching is generally carried out sequentially, with the successive biaxial stretching, in which first longitudinal (in the machine direction) and then stretched transversely (perpendicular to the machine direction) is preferred. The Further description of the film production takes place using the example of a Flat film extrusion with subsequent sequential stretching.

First, as is usual in the extrusion process, the polymer or the poly mixture of the individual layers compressed and liquefied in an extruder, the additives optionally added already in the polymer or in the Polymer mixture can be included. The melts are then simultaneously pressed through a flat die (slot die), and the pressed multi-layer Film is placed on one or more take-off rolls at a temperature of 10 to 100 ° C, preferably 10 to 50 ° C, deducted, wherein it cools and solidifies.

The film thus obtained is then stretched lengthways and crossways to the direction of extrusion, which leads to an orientation of the molecular chains. Longitudinal stretching is preferred wise at a temperature of 70 to 130 ° C, preferably 80 to 110 ° C usually with the help of two according to the desired stretching ratio Carry out rollers running at different speeds and preferably cross-stretch at a temperature of 120 to 180 ° C with the help of an appropriate Kluppenrah mens. The longitudinal stretching ratios are in the range from 3 to 8, preferably 4 to 6. The transverse stretching ratios are in the range from 5 to 10, preferably 7 to 9.

Basically, it is necessary for the longitudinal stretching of a film by means of rollers Heat the film through the roller contact to a minimum temperature so that a uniform stretching is possible. In connection with the present Invention has been found that the outer layers of copolymers or terpolymers I increasingly tend to stick to the rollers of the longitudinal drafting system. It showed is that a film whose top layer consists only of copolymers or terpolymers I in  usual stenter process can not be stretched in the longitudinal direction by means of rollers. If the temperatures are too high, deposits on the longitudinal stretching rollers result optical defects. At lower temperatures, stretching bends and Breaks. No suitable temperature range could be found in which the Film can be produced on a production scale.

Surprisingly, the additives described in the top layer the tendency of the top layer raw material to stick and the deposits on the Longitudinal stretching rollers significantly reduced. So a temperature range could be found are allowed to produce the film on a production scale. It was found that by adding the waxes, polyethylenes or other additives a longitudinal stretching at a temperature in the range of the melting point of the respective top layer raw material is possible. A temperature in the Range of 10 ° C, preferably 5 ° C, above or below the melting point of the Copolymers or terpolymers I selected.

The stretching of the film is followed by its heat setting (heat treatment), the film being at a temperature of 100 to 160 ° C for about 0.1 to 10 s is held. Then the film in the usual way with a Rewinder wound up.

After the biaxial stretching, one or both surfaces are preferred Film treated with one of the known methods plasma, corona or flame. The Treatment intensity is generally in the range from 35 to 50 mN / m, preferably 37 to 45 mN / m.

Corona treatment is advantageously carried out in such a way that the film is passed between two conductor elements serving as electrodes, with such a high voltage, usually alternating voltage, between the electrodes  (about 5 to 20 kV and 5 to 30 kHz), is that spray or Corona discharges can take place. By spray or corona discharge the air above the film surface is ionized and reacts with the molecules the film surface, so that polar inclusions in the essentially unpo laren polymer matrix arise.

The surface treatment such. B. Corona treatment can both immediately the production of the label film as well as at a later time, e.g. B. immediately before the labeling process.

According to the invention, the label film is used in various methods for labeling of containers made of plastics, especially for in-mold and Themolabelling process, using no glue or adhesion promoters, coatings or similar aids after film production in a separate one Work step must be applied.

Furthermore, it was found that the labels can also be used on other materials such as For example, glass, aluminum, wood or tinplate adhere very well, with These materials are suitable for labeling using thermal labeling.

The containers to be labeled made of thermoplastic polymer can according to the different processes and made of different materials be or be made. The container can be both solid-walled and also be foamed-walled. The latter can be made from granular precursors, contain the corresponding blowing agent, are foamed in the mold or from foamed sheets are formed by deep drawing. Depending on the Requirements for the container and the process for its manufacture come materials as diverse as polypropylene (PP), high or low density (HD-PE or LD-PE or LLD-PE), polystyrene (PS), polyvinyl chloride  (PVC), polyethylene terephthalate (PET), their copolymers and other polymers, in In individual cases, mixtures of such polymers for the production of the containers for Commitment. Processes for producing the containers are, for example, injection molding, Thin wall injection molding, blow molding, deep drawing, thermoforming or Injection stretch blow molding.

The labeling of the containers made of thermoplastic polymer with the label film according to the invention can be carried out by the IML process and thereby combined with all the above-mentioned common processes for the production of containers become. All variants or combinations have in common that the label cut to size before forming or manufacturing the container (cut-in-place or Cut) and inserted into the mold so that the printed outside the label is in contact with the mold and later the visible side of the container forms. The inside of the label faces the container. When forming or manufacture of the container joins the inner surface of the label under the influence of pressure and temperature with the container.

The in the shaping or manufacture of the container from thermoplastic The temperatures and pressures to be used in the polymer depend on the Properties of the molding compositions used and according to the requirements of selected method of manufacturing or molding the container. This Conditions are in the main outline in different manuals of the Plastics processing (including "plastic paperback", edited by Hj. Saechtling, Hanser-Verlag Munich-Vienna) and in the recommendations of Manufacturers of the corresponding molding compounds described.

The label film can also be used according to the invention for labeling containers the thermal labeling process can be used. Thermal labeling is in the sense the present invention, a labeling method in which the label under  Exposure to heat (without additional auxiliaries) on a previously, d. H. in one separate step, the container produced is applied. A surprising variety of container materials can be labeled, for example glass, metal such as B. tinplate or aluminum or thermoplastic polymers as described above for the in-mold label process have been described.

According to the invention, it is not necessary to add the label on the inside to be provided with adhesives and auxiliaries, adhesives or coatings. It is enough Exposure to heat and possibly additional pressure around the label to apply its inner cover layer to the surface of the container wall. In this case, either the label and / or the container which has already been molded in a separate process step, after container manufacture, but before Application of the label to a suitable temperature range, the container should remain as dimensionally stable as possible at these temperatures. The suitable temperature range depends on the material of the container and is, for example, 90 to 140 ° C for PP, 70 to 120 ° C for PE-HD, for PE-LD and -LLD 60 to 115 ° C, for PET 130 to 170 ° C, for PC 110 to 145 ° C, for hard PVC 70 to 130 ° C, for soft PVC depending on the setting 50 to 120 ° C and for PS 70 determined up to 95 ° C. Is preferred when labeling with the invention Label film for PP a temperature range of 95 to 130 ° C maintained, for PE-HD from 75 to 115 ° C, for PE-LD and -LLD from 65 to 105 ° C, for PET from 135 to 165 ° C, for PC from 120 to 140 ° C, for rigid PVC from 80 to 125 ° C, for soft PVC depending on the setting from 60 to 120 ° C and for PS from 75 to 90 ° C.

The additional application of a suitable contact pressure can be helpful along with exposure to heat. The print can cover the entire surface act on the label by, for example, corresponding "sealing tools" or stamp the label flat onto the container. This sets a flat  Container shape in the area of the label to be applied. Possibly rollers or brushes can be passed over the label and so the label press over its entire surface. This is especially true with rounds Container shapes advantageous. The contact pressure can be within wide limits vary and depends on the process and the shape of the container.

Especially with containers with thin and flat walls Process variants preferred, in which the container wall by a appropriate back pressure is stabilized. Come with cups and bowls for this purpose, matrices or counter-rollers lying against the inner wall, and especially with bottles, also air overpressure into consideration.

If necessary, the label can only be applied to the partial area with the Container wall (patch labeling) can be connected. In this variant, a Adhesive applied to the entire surface of the label, which is then applied to the Container wall is applied. In the label film according to the invention there is no need to apply the adhesive. One or more labels can be placed on a container be applied.

Another variant of the subsequent container labeling is the All-round labeling, in which the label in the form of a strip around the Container wrapped around and only at the ends of the strip with the Container wall or with the label itself by applying a Melt adhesive, which is used for the adhesion of the label to the container or the label caring about yourself, being connected. The film according to the invention is omitted the glue application. The heating in the area of the strip is sufficient adheres to the container or the film.

Depending on the method variant selected, it can be advantageous, also or only  heat the label film before application. In these cases the preferred temperature range of the inner film surface at 70 to 130 ° C, particularly preferred at 80 to 125 ° C. Surprisingly, only very Low temperatures are required to ensure good adhesion by means of thermal labeling of the label.

Depending on the printing process used, the process for producing the Containers and the mechanical equipment at the location of the label application can the labels according to the "cut-in-place" process or according to the "cut & stack" - Procedures are fed.

In a further application, the label film can also be part of a Laminates are used, which in turn in the manner described as In-mold or thermal label can be used. The label films according to the invention then form the inside of the laminate, so that according to the invention the inner surface of the label film in the same way faces the container and ensures good adhesion to the container. Typically, on the outside of the label, more or less thin, transparent films, in particular transparent BOPP films for use. there the printed image is located between the inner and the outer film. The two Foils are glued together with a suitable adhesive.

measurement methods

The following measurements were carried out to characterize the raw materials and the films methods used:

melt Flow Index

The melt flow index was according to DIN 53 735 at 21.6 N load and 230 ° C  measured.

melting point

DSC measurement, maximum of the melting curve, heating rate 20 ° C / min.

cloudiness

The haze of the film was measured according to ASTM-D 1003-52.

shine

The gloss was determined in accordance with DIN 67 530. The reflector value was measured as optical parameter for the surface of a film. Based on the standards ASTM-D 523-78 and ISO 2813 the angle of incidence was 60 ° or 85 ° set. A light beam hits the at the set angle of incidence flat test surface and is reflected or scattered by it. The on the Light beams striking photoelectronic receivers are called proportional electrical size is displayed. The measured value is dimensionless and must be compared with the Angle of incidence can be specified.

surface tension

The surface tension was measured using the so-called ink method (DIN 53 364).

printability

The corona-treated films were 14 days after their production (short-term assessment) or printed 6 months after their production (long-term assessment). The color adhesion was assessed using an adhesive tape test. Could use tape little color can be removed, so the color adhesion was moderate and clear color separation with poorly assessed.  

roughness

As a measure of the roughness of the inside of the foils, the roughness values Rz The foils were based on DIN 4768 Part 1 and DIN 4777 and DIN 4772 and 4774 using a perthometer type S8P from Feinprüf Perthen GmbH, Göttingen, measured according to the tactile cut method. The measuring head, a Single-skid probe system according to DIN 4772, was with a probe tip with a radius of 5 µm and a flank angle of 90 ° with a contact force of 0.8 to 1.12 mN as well a skid with a radius of 25 mm in the sliding direction. The vertical Measuring range was set to 62.5 µm, the scanning distance to 5.6 mm and the cut-off of the RC Filters set to 0.25 mm according to DIN 4768/1.

Production of the foils example 1

It was made by coextrusion and subsequent gradual orientation in longitudinal and transverse direction was a transparent three-layer film consisting of the Base layer B, an inner cover layer A and an outer cover layer C with a total thickness of 60 microns. The cover layer A had a thickness of 2.0 µm and the cover layer C a thickness of 0.7 µm. The layers were as follows composed:

Base layer B

99.64% by weight propylene homopolymer with a melting point of 165 ° C. and a melt flow index of 3.4 g / 10 min and a chain isotaxy index of 94%
0.10% by weight erucic acid amide (lubricant)
0.10% by weight Armostat 300 (antistatic)
0.03% by weight neutralizing agent (CaCO ₃

)
0.13% by weight stabilizer (Irganox)

Top layer A

94.5 wt .-% terpolymer of ethylene, ethyl acrylate and maleic anhydride with an ethylene content of 91 wt .-% ethyl acrylate content of 5 wt .-% and a maleic anhydride content of 4 wt .-% based on the terpolymer. The melt flow index was 5.0 g / 10 min (at 190 ° C, 21.6 N).
0.5% by weight SiO ₂

as an antiblocking agent with an average particle size of 4 µm
5.0% by weight polyethylene wax with a number average molecular weight Mn of 2000

Top layer C

99.54% by weight random copolymer of ethylene and propylene with a melt flow index of 6.0 g / 10 min and an ethylene content of 6% by weight, based on the copolymer
0.22% by weight of SiO ₂

as an antiblocking agent with an average particle size of 4 µm
0.20% by weight stabilizer (Irganox 1010 / Irgafos 168)
0.04% by weight neutralizing agent (Ca stearate)

The manufacturing conditions in the individual process steps were:

extrusion:
temperatures
Base layer B: 260 ° C
Top layer A: 230 ° C
Top layer C: 240 ° C
Take-off roller temperature: 20 ° C

Longitudinal stretching:
Temperature: 100 ° C
Longitudinal stretch ratio: 1: 4.5

Transverse stretching:
Temperature: 165 ° C
Lateral stretch ratio: 1: 9

fixation:
Temperature: 140 ° C
Convergence: 10%

Printing preparation:
Top layer A; Corona 10000 V / 10000 Hz
Top layer C: Corona 10000 V / 10000 Hz

The transverse stretching ratio of 1: 9 is an effective value. This The effective value is calculated from the final film width B, reduced by two times Hem strip width b divided by the width of the elongated film C, also reduced by twice the hem width b.

Example 2

A three-layer film was produced as described in Example 1. in the In contrast to Example 1, an additional 5.1% by weight was added to the base layer Calcium carbonate (chalk) with an average particle diameter of 2 µm as Vacuole-initiating particles (chalk) incorporated. The polypropylene content was reduced accordingly. The manufacturing conditions in each Process steps were as in Example 1. The film was opaque. In addition the composition of the top layer A changed as follows:

Top layer A

92.5% by weight of terpolymer of ethylene, ethyl acrylate and maleic anhydride with an ethylene content of 91% by weight of ethyl acrylate content of 5% by weight and a maleic anhydride content of 4% by weight, based on the terpolymer. The melt flow index was 5.0 g / 10 min [at 190 ° C., 21.6N]
0.5% by weight SiO ₂

as an antiblocking agent with an average particle size of 4 µm
2.0% by weight of polyethylene wax with a molecular weight Mn (number average) of 2000
5.0% by weight HDPE with an MFI of 15 g / 10 min (190 ° C / 2.16 kg) and a melting point of 133 ° C (DSC @ 10 ° C / min).

The film was in addition to the labeling described below applications used as lidding film and on yoghurt cups made of polystyrene, and applied to an impression part made of polypropylene. The film showed on both Containers have good adhesion and can then be easily and Remove without residue. The good adhesion could be achieved at temperatures of approx. 80 ° C can be reached. As a result, the seal edge of the yogurt cup remained reliable dimensionally stable.

Example 3

A three-layer film was produced as described in Example 2. in the In contrast to Example 2, an additional 2.8% by weight was added to the base layer Titanium dioxide (rutile) incorporated as a pigment. The polypropylene content was reduced accordingly. The manufacturing conditions in each Process steps were as in Example 2. The film was white-opaque. additionally the composition of the top layer A was changed as follows:

Top layer A

89.5 wt .-% terpolymer of ethylene, ethyl acrylate and maleic anhydride with an ethylene content of 91 wt .-% ethyl acrylate content of 5 wt .-% and a maleic anhydride content of 4 wt .-% based on the terpolymer. The melt flow index was 5.0 g / 10 min [at 190 ° C., 21.6N]
0.5% by weight SiO ₂

as an antiblocking agent with an average particle size of 4 µm
10.0% by weight HDPE with an MFI of 15 g / 10 min (190 ° C / 2.16 kg) and a melting point of 133 ° C (DSC @ 10 ° C / min).

Example 4

A film was described as in Example 3, but with an additional one Interlayer. The intermediate layer D was between the Base layer B and the top layer C attached and was made of pure Propylene homopolymer with a melting point of 165 ° C and a Melt flow index of 3.4 g / 10 min and a chain isotaxy index of 94% built up. The manufacturing conditions in the individual process steps were as in Example 3. In addition, the composition of the outer layer A changed as follows:

Top layer A

89.5 wt .-% terpolymer of ethylene, ethyl acrylate and maleic anhydride with an ethylene content of 91 wt .-% ethyl acrylate content of 5 wt .-% and a maleic anhydride content of 4 wt .-% based on the terpolymer. The melt flow index was 5.0 g / 10 min [at 190 ° C., 21.6 N)
0.5% by weight SiO ₂

as an antiblocking agent with an average particle size of 4 µm
10.0% by weight random copolymer of ethylene and propylene with a melt flow index of 6.0 g / 10 min and an ethylene content of 6% by weight, based on the copolymer.

Example 5

One film was described as in Example 4, but with a second one Intermediate layer E on the opposite side. In addition the composition of the top layer A changed as follows:

Top layer A

87.5 wt .-% terpolymer of ethylene, ethyl acrylate and maleic anhydride with an ethylene content of 91 wt .-% ethyl acrylate content of 5 wt .-% and a maleic anhydride content of 4 wt .-% based on the terpolymer. The melt flow index was 5.0 g / 10 min [at 190 ° C., 21.6N]
0.5% by weight SiO ₂

as an antiblocking agent with an average particle size of 4 µm
2.0% by weight of polyethylene wax with a molecular weight Mn (number average) of 2000
10.0% by weight random copolymer of ethylene and propylene with a melt flow index of 6.0 g / 10 min and an ethylene content of 6% by weight, based on the copolymer.

The intermediate layers D and E had the following compositions:

First intermediate layer D

90.58% by weight propylene homopolymer with a melting point of 165 ° C. and a melt flow index of 3.4 g / 10 min and a chain isotaxy index of 94%
9.0% by weight of titanium dioxide (rutile) as a pigment
0.12% by weight erucic acid amide
0.14% by weight Armostat 300
0.03% by weight neutralizing agent (CaCO ₃

)
0.13% by weight stabilizer (Irganox)

Second intermediate layer E

97.58% by weight of a random copolymer of ethylene and propylene with a melt flow index of 6.0 g / 10 min and an ethylene content of 6% by weight, based on the copolymer
2.0% by weight of polydimethylsiloxane (PDMS) with a viscosity of 30,000 mm ²

/ s
0.18% by weight erucic acid amide
0.20% by weight stabilizer (Irganox 1010 / Irgafos 168)
0.04% by weight neutralizing agent (Ca stearate)

The manufacturing conditions in the individual process steps were as in Example 2.

Comparative Example 1

It became a transparent three-layer film, as described in Example 1 manufactured. In contrast to Example 1, this was in the inner cover layer A. Terpolymer of ethylene, ethyl acrylate and maleic anhydride through a statistical copolymer of ethylene and propylene with a melt flow index of 6.0 g / 10 min and an ethylene content of 6 wt .-% based on the copolymer replaced. The manufacturing conditions in the individual process steps were as in example 1.

Comparative Example 2

A three-layer opaque film was produced as described in Example 2. In contrast to Example 2, the terpolymer was in the inner cover layer A. from ethylene, ethyl acrylate and maleic anhydride by a statistical Copolymer of ethylene and propylene with a melt flow index of 6.0 g / 10 min and an ethylene content of 6 wt .-% based on the copolymer replaced. The Manufacturing conditions in the individual process steps were as in Example 2.

Comparative Example 3

A three-layer white-opaque film as described in Example 3 was obtained manufactured. In contrast to Example 3, the HDPE content was the inner Cover layer A increased to 50% by weight. The manufacturing conditions in each Process steps were as in Example 3.  

Comparative Example 4

A four-layer white-opaque film as described in Example 4 was obtained manufactured. In contrast to Example 3, the copolymer content was the inner Cover layer A increased to 50% by weight. The manufacturing conditions in each Process steps were as in Example 4.

Comparative Example 5

A five-layer white-opaque film as described in Example 5 became manufactured. In contrast to Example 3, the copolymer content was the inner Cover layer A increased to 25% by weight. The manufacturing conditions in each Process steps were as in Example 5.

Comparative Example 6

An attempt was made to use a three-layer white-opaque film, as in Example 1 described to manufacture. In contrast to Example 1, the addition of No polyethylene wax or sylobloc. The manufacturing conditions in the individual process steps were as in Example 1. Due to massive Deposits on the rolls of the longitudinal stretching could not produce a film become.

The films according to the examples and comparative examples were in-mold and Thermolabelling process used and with regard to their adhesive properties compared. Various container materials were used for the in-mold test series the respective processing temperatures customary for the polymer into one Injected container shape. Before the actual spraying process a film was made according to the examples and the comparative examples inserted into the container shape in such a way that the inside of the film was facing the container to be molded. After Making the labeled container was the adhesive strength of each  Label checked. The results are summarized in Table 1.

For the thermolabelling test series, containers from different Polymers used. In individual cases, such as B. was there in the glass container Container preheated slightly (approx. 50-60 ° C). A corresponding film cut was applied to the respective container under the influence of a manual contact pressure at a temperature of 120 to 130 ° C using a manual sealing piston ironed. After the container labeled in this way has cooled down The adhesive strengths were examined at room temperature. The results are in Table 2 summarized.  

Table 1

Table 2

Claims (35)

1. Use of a multi-layer coextruded polyolefin film consisting of a base layer and at least one inner cover layer, the base layer and the inner cover layer being extruded together and simultaneously through a multi-layer die and then stretched together biaxially, characterized in that this inner cover layer is at least 70% by weight. a copolymer or terpolymer which is composed at least of olefin and unsaturated carboxylic acid or their esters or their anhydride and contains at most 30% by weight of an additive, the details in% by weight in each case relating to the weight of the inner cover layer , 2. Label sheet according to claim 1, characterized in that the The additive is a wax, preferably a polyethylene wax or a macrocrystalline paraffin (paraffin wax) or a microcrystalline wax (Micro wax) and an average molecular weight Mn (number average) Mn of 200 to 5000, preferably 200 to 1000 and the wax has a melting point from 70 to 120 ° C. 3. label film according to claim 1 and / or 2, characterized in that the wax is a polyethylene wax with a weight average ratio to number average Mw / Mn is from 1 to 2 and that the wax in an amount of 0.5 to 30 wt .-% based on the weight of the layer is included. 4. label film according to one or more of claims 1 to 3, characterized in that the additive is a polyolefin, a Hydrocarbon resin, polystyrene, polyester or polyamide, preferably one a propylene co or terpolymer, a linear and branched polyethylene  is low (LLDPE, LDPE), medium or high (HDPE). 5. label film according to one or more of claims 1 to 4, characterized in that the inner cover layer 70 to 99.5 wt .-% of Contains copolymers or terpolymers I. 6. label film according to one or more of claims 1 to 5, characterized in that the copolymer I more than 65 wt .-% Olefin units, preferably ethylene units and at most 35% by weight unsaturated monocarboxylic acid units or their esters, preferably Contains acrylic acid or methacrylic acid or their esters. 7. label film according to one or more of claims 11 to 5, characterized in that the terpolymer I

• a) 65 to 96 wt .-% olefin, preferably ethylene and
• b) 3 to 34 wt .-% unsaturated carboxylic acids or their esters, preferably acrylic acid or methacrylic acid or their esters and
• c) 1 to 10% by weight of an unsaturated mono- or dicarboxylic acid different from (b) or its ester or its anhydride, preferably maleic anhydride or glycidyl methacrylate.

8. label film according to one or more of claims 1 to 7, characterized in that the unsaturated carboxylic acid unit, (b) Is acrylic acid ester, preferably an acrylic acid methyl, ethyl, n-propyl, -i-propyl, n-butyl, i-butyl, sec-butyl or tert-butyl ester. 9. label film according to one or more of claims 1 to 8, characterized in that the inner cover layer antiblocking agents, preferably 1 to 5% by weight.   10. label film according to one or more of claims 1 to 9, characterized in that the inner cover layer is a lubricant, preferably contains erucic acid amide and / or polydimethylsiloxane. 11. label film according to one or more of claims 1 to 10, characterized in that the inner cover layer is a mixture of two contains or more of the additives, preferably wax in an amount from 1 to 10% by weight and HDPE in an amount from 1 to 20% by weight. 12. label film according to one or more of claims 1 to 11, characterized in that the inner cover layer corona, plasma or Is flame-treated. 13. label film according to one or more of claims 1 to 12, characterized in that the film on the inner cover layer opposite side of the base layer another outer cover layer has, which is composed of copolymers and / or terpolymers II. 14. label film according to one or more of claims 1 to 13, characterized in that the surface of the outer cover layer Corona, plasma or flame treated. 15. Label film according to one or more of claims 1 to 14, characterized in that the outer cover layer contains antiblocking agents, preferably SiO ₂ . 16. label film according to one or more of claims 1 to 15, characterized in that one or both-sided intermediate layer (s)  olefinic polymers between the base and the top layers is / are appropriate. 17. Label film according to claim 16, characterized in that that intermediate layer, which is below the inner cover layer additives, preferably waxes, hydrocarbon resin, Polystyrene, polyester or polyamide, linear or branched polyethylene low (LLDPE, LDPE), medium or high (HDPE) density, and optionally contains lubricants, antistatic agents and / or antiblocking agents. 18. label film according to one or more of claims 1 to 16, characterized in that the thickness of the film is 15 to 150 µm, in particular 25 to 90 microns, with the base layer about 40 to 60% of Total thickness. 19. label film according to one or more of claims 1 to 17, characterized in that the base layer 70 to 99 wt .-% of a Propylene polymers, preferably propylene homopolymer, contains. 20. label film according to one or more of claims 1 to 18, characterized in that the base layer is opaque and contains vacuole-initiating fillers and optionally pigments. 21. label film according to one or more of claims 1 to 19, characterized in that the opaque base layer 0.5 to 30 wt .-% contains vacuole-initiating fillers and / or 1 to 10% by weight of pigments. 22. label film according to one or more of claims 1 to 20, characterized in that the base layer lubricant and / or  Antistatic, preferably tertiary aliphatic amine, contains. 23. A method of manufacturing a labeled container, thereby characterized in that a label film according to one of claims 1 to 21 applied to a container using in-mold or thermolabelling processes and the inner cover layer faces the container and the opposite surface forms the visible side of the container. 24. The method according to claim 22, characterized in that on the Surface of the inner cover layer of the label film no adhesive, none Adhesive layer and no coating after the production of the label film and is applied before labeling the container. 25. The method according to claim 22, characterized in that the container made of thermoplastic, preferably PP, PE, PS, PET PVC or PC is. 26. The method according to claim 22, 23 and / or 24, characterized in that that labeling is thermolabelling and the label with its inner Cover layer at a temperature of over 50 ° C, the container and / or the label is heated, applied to a molded container, the label being applied by means of pressure, rollers or brushes. 27. Labeled container manufactured according to one of the methods 22 to 25. 28. A method for labeling, characterized in that a Label film according to one of claims 1 to 26 by means of thermal labeling Process on a surface made of wood, ceramic, metal, preferably Aluminum, tinplate or glass is applied.   29. A process for producing a multilayer composite, thereby characterized in that the label film against another film thermoplastic polymer or against a substrate made of paper, wood, or Metal is laminated or laminated. 30. Use of a film according to claim 1 for printing, coating with cold seal adhesive coatings or for metallization. 31. The method, characterized in that a biaxially oriented Polyolefin film consisting of a base layer and at least one inner layer Top layer, characterized in that this inner top layer at least 50 wt .-% of a copolymer or terpolymer I, which at least from olefin and unsaturated carboxylic acid or their esters or their Anhydride is built up, and contains at most 50 wt .-% of an additive, the details in% by weight refer to the weight of the first Cover with their inner top layer using thermal labeling as removable protective film on a surface made of tinplate, wood, glass or Metal, preferably aluminum is applied. 32. Use of a multilayer biaxially oriented polyolefin film a base layer and at least one inner cover layer, thereby characterized in that this inner cover layer at least 70 wt .-% of a Copolymers or terpolymers which are at least composed of olefin and unsaturated Carboxylic acid or its esters or its anhydride is built up, and contains at most 30% by weight of an additive, the details in Wt .-% each refer to the weight of the inner cover layer as Lidding film.   33. Use according to claim 31 as a cover film on containers made of PS, PP, PE, PET, PVC, PC metal or tinplate. 34. Use according to claim 30 or 31, characterized in that the cover film at a temperature of at least 70 ° C., preferably 80 up to 100 ° C is applied to the container. 35. Process for producing a polyolefin film according to the Coextrusion process in which the individual layers of the film corresponding melts simultaneously and together through a flat nozzle coextruded, the film thus obtained for solidification on one or more Rolled off, then stretched the multilayer film, the stretched film is heat set, characterized in that the film is a Cover layer which has at least 70 wt .-% of a Co or Terpolymers, which at least from olefin and unsaturated Carboxylic acid or its esters or its anhydride is built up, and contains at most 30% by weight of an additive, the details in Wt .-% each refer to the weight of the inner cover layer and the The film is stretched longitudinally by means of heated rollers and the temperature for longitudinal stretching in a range of 10 ° C above or below the Melting point of the co- or terpolymer varies.