SK287172B6 - Paper-type plastic film, method of making such a film and use thereof - Google Patents

Abstract

The invention relates to an easily tearable biaxially oriented polyolefin multilayered film having qualities similar to paper. Said film contains polymer, natural or mineral fibers in at least one layer. This polymer film has a low initial strength laceration.

Description

Technical field

The present invention relates to a synthetic paper made from a coextruded, biaxially oriented plastic film having improved initial tearability and controllable crack propagation capability. The invention further relates to a process for the manufacture of said synthetic paper.

BACKGROUND OF THE INVENTION

The success of biaxially oriented plastic films, especially films that include thermoplastic polymers, especially biaxially oriented polypropylene films, is essentially based on their excellent mechanical strength combined with relatively low weight, good barrier properties and good weldability. Said polyolefin films protect the packaged article from its rapid drying out and from the loss of its odor, with only a very small amount of said material being used to provide these functions.

The only requirement that is not met when using this type of packaging, which otherwise meets customer needs for a hygienic, visually appealing, tightly sealed and robust packaging, is the requirement for easy and controllable opening. Failure to comply with this latter requirement is the subject of customer complaints in the case of packaging that includes polyolefin films and is considered a disadvantage of such packaging over paper packaging.

Uniaxially oriented films, such as tape products, have a distinctly low initial tear strength and / or a high tendency to rupture in the direction of said orientation and can therefore be easily torn at first and further torn in this direction. However, the use of uniaxially oriented films is unsuitable in many areas, due, among other things, to insufficient mechanical strength in the transverse direction. On the other hand, in the biaxial orientation process, a product is obtained which has the desired high strength (modulus of elasticity) in both directions, but said preferred directions are only limited to a limited extent due to said process. As a result, when opening packages of such films (for example, biscuit bags), it is first necessary to exert a great force to tear said film. However, as soon as said film is damaged or partially torn, the resulting crack propagates completely uncontrolled, even at very low tensile forces. This drawback, which is too high an initial tear strength and an uncontrolled crack propagation, greatly reduces the acceptability of paper wrappers made of such a film by end-users, despite the stated advantages of such wrappers.

One solution to this problem is to provide the foil wrap with a sealing seam. For example, EP 95 / P003 discloses a film which, instead of a layer for heat sealing the package, comprises a peeling layer and, in addition, the film has a special layered structure. This solution makes it possible to reopen the package made of said foil in a controlled manner at the point where the package has been closed, in particular at the point of said seam.

As a further solution to the problem described above, a multilayered structure with a predetermined bursting point, i.e. a " j. with a layer having a particularly low mechanical strength. Upon opening, said film is first torn at said predetermined breaking point. This principle has now been implemented both in the production of co-extruded films and in the production of multi-layer laminates.

Another known solution is the additional mechanical insertion of a predetermined rupture point of the film in the form of a perforation or notch.

In some cases, a special tape (usually polyester) is used to facilitate the controlled opening of the package and is retracted when the package is opened. This solution is very expensive and therefore not used in all areas of the market.

SUMMARY OF THE INVENTION

It is an object of the present invention to describe a synthetic paper that combines the advantages of a biaxially oriented plastic film with an initial tear and crack propagation similar to that of paper. When using the synthetic paper of the present invention, it should not be necessary to use any other means, such as a tape to open the package by pulling on the tape, the notch or a complicated layered structure.

The object is achieved by using a biaxially oriented polymeric film comprising at least one layer, the layer comprising a fiber layer formed from a thermoplastic polymer and comprising cellulose fibers, cotton fibers, polypropylene fibers, polyethylene fibers, polyester fibers, polyamide fibers, polyimide fibers fibers, wolastonite fibers or fibers consisting of calcium silicate.

The use of asbestos or glass fibers, in particular long glass fibers, according to the invention is excluded. This is due to the potential risk (carcinogenicity, inhalation) to workers in the production and processing of such films, and the disadvantage of glass fibers is their high abrasion capability, resulting in excessive wear of the components of the equipment in which the glass fiber-containing material is processed.

The paper-like film of the present invention may be translucent to transparent, or may be in the form of a matt film, depending on the intended use of the film. For the purposes of the present invention, the term "matt film" means an opaque film whose light transmittance (measured according to ASTM-D 1003-77) is at most 70 percent, preferably at most 50 percent.

At least one film layer of the present invention comprises mineral fibers such as wollastonite or polymer, or natural fibers. The fiber-containing layer of the present invention, which contributes to behavior similar to that of paper, is formed from thermoplastic polymers.

A group of thermoplastic polymers that can form a polymer matrix from a layer comprising said fibers include polyimides, polyamides, polyesters, PVC, and polyolefins made from olefinic monomers containing from 2 to 8 carbon atoms. Particularly suitable are polyamides and polyolefins, of which propylene polymers, ethylene polymers, butylene polymers, cycloolefin polymers or copolymers containing propylene, ethylene and butylene units or cycloolefins are preferably used. Generally, the layer comprising said fibers comprises at least 50 weight percent, preferably from 70 weight percent to 99 weight percent, particularly preferably from 90 weight percent to 98 weight percent, in all cases based on the total weight of said layer, of a thermoplastic polymer.

Preferred polyolefins of the present invention are propylene polymers. These propylene polymers comprise from 90 weight percent to 100 weight percent, preferably from 95 weight percent to 100 weight percent, particularly preferably from 98 weight percent to 100 weight percent, propylene and have a melting point of 120 ° C or more, preferably in the range of 130 ° C to 170 ° C, and their melt index at 230 ° C and a load of 21.6 Newtons (see DIN 53 735 standard) is generally in the range of 0.5 grams / 10 minutes to 15 grams / 10 minutes, preferably in the range of 2 grams / 10 minutes to 10 grams / 10 minutes. Preferred propylene polymers for forming the base layer of the present invention are isotactic propylene homopolymers containing 15 weight percent or less of an atactic fraction, ethylene-propylene copolymers containing 10 weight percent or less ethylene, propylene copolymers with olefins containing from 4 to 8 carbon atoms and containing from 4 to 8 carbon atoms % by weight or less of said olefin; propylene, ethylene and butylene terpolymers containing 10% by weight or less of ethylene and containing 15% or less by weight of butylene. An isotactic propylene homopolymer is particularly preferably used to form said layer. The percentages given are in each case based on the total weight of the polymer.

Equally suitable for use in the present invention is a mixture of said propylene homopolymers and / or copolymers, and / or terpolymers with other polyolefins, especially polyolefins made from monomers containing from 2 to 6 carbon atoms, said mixture containing at least 50% by weight, preferably at least 75 weight percent propylene polymer. The group of these other polyolefins in the polyolefin compositions to be used according to the invention includes, in particular, HDPE, LDPE, VLDPE and LLDPE, the proportion of these polyolefins in the blends not exceeding 15% by weight. The percentages given are in each case based on the total weight of the polymer blend.

In addition to the thermoplastic polymer, the fiber-containing layer of the film of the present invention comprises fibers up to a maximum of 50 weight percent, preferably from 0.5 weight percent to 10 weight percent, more preferably from 1 weight percent to 5 weight percent, relative to the weight of said fiber-containing layer.

Said fibers may be made of different materials. Suitably, fibers made from thermoplastic polymers, crosslinked thermoplastic polymers, amorphous polymers, semi-crystalline polymers, stabilized natural fibers or crystalline mineral fibers are used.

Preferably, fibers made of thermoplastic polymers such as polyolefins, polyethylenes, polypropylenes, cycloolefin polymers, copolymers, polyesters, polyamides, polyimides or polyaramides are used. Furthermore, it is also possible according to the invention to use fibers made of crosslinked thermoplastic polymers with radiation crosslinked or chemically crosslinked thermoplastic polymers containing the corresponding reactive groups. Furthermore, stabilized natural fibers such as cotton fibers or cellulose fibers or crystalline mineral fibers such as wollastonite or various calcium silicates such as Tremin 939 supplied by Quarzwerke GmbH, Frechen, Germany, and other minerals having the corresponding minerals may be used. morphology. For the purposes of the present invention, the term mineral fibers' does not include glass fibers. In the context of the development of the present invention, it has been found that the use of glass fibers in biaxially oriented films is inappropriate. In addition, the use of glass fibers seriously damages the slits and rollers of the biaxially oriented film production apparatus.

The dimensions of the fiber, in particular its length and diameter, depend on the particular field of application of the film according to the present invention as well as the thickness of the film. The average fiber diameter values are preferably in the range of 1.5 microns to 50 microns, preferably in the range of 3 microns to 20 microns, and the fiber length is in the range of 10 microns to 250 microns, preferably in the range of 20 microns to 50 microns, the ratio of fiber length to fiber diameter (L / D) is in the range of 5 to 50, preferably in the range of 10 to 30.

In another embodiment of the invention said fibers may be provided with a suitable coating. Particularly preferred are coatings which improve the rheological behavior and compatibility of the fibers with the polymer matrix of the present invention. Said coating may optionally contain a stabilizer, especially when using polymer fibers. Preferably, organic coatings are used to control the aforementioned compatibility of the fibers with the polymer matrix of the present invention.

Of the fibers made of thermoplastic polymers, matt fibers are particularly preferred. These fibers contain opacifying agents, preferably titanium dioxide, which are added to the fiberized mixture during the manufacture of said fibers, in order to reduce the natural gloss of said polymeric fibers. Thus, titanium dioxide pigmented fibers are produced, the use of which in the fiber-containing layer of the film of the present invention is particularly advantageous. These embodiments of the present invention are characterized by increased whiteness and, particularly, paper resembling the appearance of the film of the present invention.

Said fibers must be substantially stable to processing conditions, i. j. against extrusion conditions and subsequent orientation of the resulting film. In particular, the structure of said fibers must be substantially preserved during the manufacture of the film according to the invention. For this purpose, the material, in particular in the case of fibers made from thermoplastic polymers, must have a sufficiently high melting point or softening temperature such that the fiber made from this material retains its shape and does not melt at the processing temperature of the polymer matrix.

Quite unexpectedly, it has been found that said fibers alter the tearing properties of the biaxially oriented film of the present invention. The tear properties of said film are much more reminiscent of the tear properties of paper. This effect is particularly unexpected in view of the knowledge of those skilled in the art of fiber reinforced plastics. It is known in the field of injection molding that fibers can be added to extrudates made of thermoplastics to produce fiber-reinforced plastics. In this way, the mechanical properties of the extrudates are improved and products made of such reinforced plastics can be used in areas where particularly high mechanical loads occur. Applying this knowledge to biaxially oriented films, it would be expected that adding fibers to the film would increase their mechanical strength. However, no increase in the strength or stiffness of the film of the present invention has been observed. On the contrary, an easier initial tear-off was observed, i. j. lower mechanical strength of the film according to the present invention.

This effect is particularly pronounced when the fibers described are used in the intermediate layer or in the base layer of the film of the present invention. The use of fibers in a thin topsheet or in thermally bondable polymers is less desirable. In this case, on the one hand, there is only a slight reduction in the initial tearability. On the other hand, the use of fibers as an additive in said topsheets can have an adverse effect on the thermal bondability of the film and the printability of the film.

Furthermore, it has been unexpectedly found that the texture of the surface of the film according to the present invention and the associated optical appearance and tactile properties of the film are similar to those of paper. The fact that the properties of the film according to the present invention are similar to those of paper is also evident from the sound perception of the initial tearing. In addition, in certain embodiments of the present invention, a film with increased water vapor permeability (or increased breathability) can be produced.

If desired, said fiber-containing layer may further comprise pigments and / or cavity-initiating particles, both of which are used in conventional amounts in both cases.

For the purposes of the present invention, pigments are understood to be incompatible particles whose presence when stretching the film substantially does not lead to the formation of cavities and their size, expressed as mean particle diameter, is in the range of 0.01 micrometer to a maximum of 1 micrometer, preferably 0, 01 micrometers to 0.7 micrometers, particularly preferably in the range of 0.01 micrometers to 0.4 micrometers. The layer usually comprises pigments in an amount of from 1 weight percent to 15 weight percent, preferably from 2 weight percent to 10 weight percent, based on the weight of the VTStvy.

Commonly used pigments are various materials such as alumina, aluminum sulphate, barium sulphate, calcium carbonate, magnesium carbonate, various silicates such as aluminum silicate (kaolin) and magnesium silicate (talc), silicon dioxide and titanium dioxide; For this group of materials, white pigments such as calcium carbonate, silica, titanium dioxide and barium sulfate are preferably used.

If desired, the film layer of the present invention may further comprise void-inducing fillers, usually in an amount of from 1 weight percent to 15 weight percent, preferably from 2 weight percent to 10 weight percent, particularly preferably from 1 weight percent up to 5 weight percent.

For the purposes of the present invention, the term " void initiator " refers to solid particles that are incompatible with the polymer matrix and their presence results in void formation when the film of the present invention is stretched, the size, nature and number of voids depending on the size of said particulate and from foil stretching conditions, such as the stretching ratio and the stretching temperature. Said tubes reduce the density of the film and make the film matt, resembling nacre, which is caused by light scattering at the "tube / polymer matrix" interface. The particle size of said cavity-initiating fillers is usually at least 1 micrometer. Typically, the particle size, expressed as a mean diameter, is in the range of 1 micron to 6 micrometers, preferably in the range of 1.5 micrometer to 3 micrometers.

The film-containing layer of the film of the present invention may, in the case of a single-layer embodiment of a paper-like plastic film, form a single layer of the film. The fiber-containing layer may also form the base layer of the multilayer film of the present invention. This fiber-containing layer forms in a preferred embodiment an intermediate layer which is applied to the base layer of the film according to the invention. Accordingly, the paper-like multilayer films of the present invention comprise, in addition to said fiber-containing layers, a base layer or intermediate layer or a top layer.

These additional layers, which are generally fiber-free, are usually made of thermoplastic polymers. These layers comprise at least 70 weight percent, preferably from 75 weight percent to 100 weight percent, more preferably from 90 weight percent to 98 weight percent, of the thermoplastic polymer. Suitable thermoplastic polymers for forming these additional layers are substantially the same as described for the fiber-containing layer of the present invention.

Suitable copolymers of the present invention are copolymers of ethylene and propylene or ethylene and butylene, or propylene and butylene, or ethylene and another olefin containing from 5 to 10 carbon atoms, or a terpolymer of ethylene, propylene and butylene or ethylene, propylene and other propylene and other olefin. containing from 5 to 10 carbon atoms or a mixture of two or more of said homopolymers, co-polymers and terpolymers.

Of these polymers, particularly preferred are random ethylene-propylene copolymers containing from 2% by weight to 10% by weight, preferably from 5% by weight to 8% by weight, ethylene, or random propylene-1-butylene copolymers containing from 4% by weight to 25% by weight percent, preferably from 10 weight percent to 20 weight percent, of butylene, wherein said percentages are in each case based on the total weight of the copolymer, or statistical ethylene-propylene-1-butylene terpolymers containing from 1 weight percent to 10 weight percent, preferably from 2 weight percent to 6 weight percent ethylene and from 3 weight percent to 20 weight percent, preferably from 8 weight percent to 10 weight percent, 1-butylene, all percentages being in each case based on the total weight of the terpolymer, or a mixture of ethylene-propylene-1-butylene terpolymer and propylene-1-butylene copolymer containing from 0.1 weight percent to 7 weight percent ethylene, from 50 weight percent to 90 weight percent propylene and from 10 weight percent to 50 weight percent 40 weight percent of 1-butylene based on the total weight of the polymer blend.

The copolymers and thermopolymers described herein typically have a melt index in the range of from 1.5 grams / 10 minutes to 30 grams / 10 minutes, preferably from 3 grams / 10 minutes to 15 grams / 10 minutes. The melting point of said polymers ranges from 120 ° C to 140 ° C. The mixture of copolymers and terpolymers described has a melt index in the range of 5 grams / 10 minutes to 9 grams / 10 minutes and a melting point in the range of 120 ° C to 150 ° C. All melt index values reported refer to measurements at 230 ° C and 21.6 Newton load (DIN 53 735). The layers formed from the copolymers and / or terpolymers in a preferred embodiment form the top layers of the thermally bondable films of the present invention.

The total thickness of the film of the present invention may vary over a wide range of values and is dependent upon the intended use of the film. In a preferred embodiment, the paper-like film of the present invention has a total thickness ranging from 5 microns to 250 microns, preferably from 10 microns to 100 microns, even more preferably from 20 microns to 60 microns.

The thickness of the described fiber-containing layer is selected independently of the thickness of the other layers and is preferably in the range of 1 micrometer to 250 micrometers, more preferably in the range of 3 micrometers to 50 micrometers.

The apparent density of the film of the present invention is from 0.3 grams / cm ³ to 1.5 grams / cm ³ (measured by the DIN standard method).

For the purposes of this invention, a base layer is a layer that constitutes more than 50 percent of the total thickness of a given film. The thickness of this layer is determined by the difference between the total thickness of the film and the thickness of the top layer (s) and the intermediate layer (s) that are applied to the base layer, and analogously to the total film thickness of the present invention over a wide range of values. By the upper layers is meant the outer layers of the film.

Thus, to further improve some properties of the polypropylene film of the present invention, said base layer, such as between the layer (s) and the top layer (s), may contain an effective amount of additives which are preferably hydrocarbon resins and / or antistatic agents, and / or anti-blocking agents. , and / or lubricants, and / or stabilizers, and / or neutralizing agents which are compatible with the polymers contained in the base layer and the topsheet (s), with the exception of anti-blocking agents which are generally incompatible with these polymers.

Another aspect of the present invention is a process for producing a multilayer film of the present invention by an extrusion process known in the art. The process conditions of the present invention are dependent upon the composition of the particular polymer matrix that constitutes the base film component of the present invention. The production method of the polypropylene film according to the invention is described in the following only as an example of a possible embodiment of the production method according to the invention.

In this method, the melt corresponding to the individual layers of the film according to the invention is coextruded through the slit, the resulting film is removed for solidification by means of one or more rollers, the solidified film is then biaxially stretched and thermally stabilized and the surface of the layer which is formed for this purpose.

Biaxial stretching (or orientation) is preferred and can be performed simultaneously or sequentially, and it is particularly preferred to perform a sequential biaxial stretching in which the film is first stretched along (i.e. in the machine direction) and then transversely (i.e., perpendicular to the direction) devices).

In this process, as is usual in a coextrusion process, the polymers or polymer mixtures, whose composition corresponds to the composition of the individual layers, are compressed and liquefied in an extruder, so that the polymers or polymer mixtures already contain the fibers described and any ingredients. The resulting melt is then co-extruded through a slot (the shape of which is suitable for the production of a flat film) and the coextruded single or multilayer film is removed by means of one or more rolls, during which the film is cooled and solidified.

The film thus obtained is then preferably stretched longitudinally and transversely, which leads to the orientation of the polymer chains contained in the film. The stretching in the longitudinal direction is preferably performed in the ratio of 3: 1 to 7: 1 and the stretching in the transverse direction is preferably performed in the ratio of 5: 1 to 12: 1. The longitudinal stretching is preferably performed using two rollers which rotate at different speeds according to the desired stretch ratio of the film. The transverse stretching of the film according to the invention is carried out by means of a corresponding tensioning frame. In the case of biaxial stretching, in principle, the stretching can also be performed simultaneously in the longitudinal / transverse direction. This simultaneous stretching of polymeric films is known in the art.

The biaxial stretching of the film of the present invention is followed by thermal stabilization (or heat treatment) when the resulting film is heated to a temperature in the range of 110 ° C to 150 ° C for a period of about 0.5 seconds to 10 seconds. Subsequently, the heat-treated film is wound with a suitable device.

It has been found to be particularly advantageous if the temperature of the one or more take-up rollers by which the extruded film is also cooled and solidified is maintained in the range of 10 ° C to 90 ° C, preferably in the range of 20 ° C to 60 ° C.

Further, the described longitudinal stretching of the film is preferably carried out at a temperature below 140 ° C, preferably at a temperature in the range of 125 ° C to 135 ° C, while the described transverse stretching of the film is preferably carried out at a temperature above 140 ° C, preferably at a temperature. in the range of 145 ° C to 160 ° C.

As already mentioned, one or both of the surfaces of the film of the present invention may be corona or flame treated, if necessary, by one of the known methods, after the described biaxial stretching of said film.

If desired, the film of the present invention may be coated, melt-coated, lacquered or laminated in a subsequent coating step using a suitable coating method, with the aim of achieving further advantageous properties in the film.

The plastic film of the present invention is characterized by a relatively easy initial tear. The force required to tear the edge of the film is greatly reduced compared to the prior art. After the initial tearing of said film, there is no undesirable crack propagation at its edge, so that the film as a whole is resistant to this initial tearing. The initial tearing of the film according to the present invention is considerably easier compared to the prior art and the resulting cracks can be further spread much more controllable. In addition, the film of the present invention has properties similar to paper properties in terms of appearance, tactile and water vapor permeability properties.

The following measurement methods were used to determine the characteristics of the fibers and films of the present invention:

Determination of mean fiber length / diameter and L / D ratio

A sufficiently thin layer of fibrous material whose properties were determined was observed under a microscope. The microscope magnification had to be adjusted so that a representative sample of said material could be examined. The length and diameter of the individual fibers and hence the L / D ratio could be measured using suitable software. By defining suitable subsets, it was possible to determine the discrete distribution of fiber length and diameter, thereby allowing the mean values to be determined.

Area weight

The basis weight was determined in accordance with DIN EN ISO 536.

Modulus of elasticity

The modulus of elasticity in the longitudinal and transverse directions has been determined in accordance with DIN EN ISO 527-1 and 527-3 respectively.

Crack propagation strength

The crack propagation strength in the longitudinal and transverse directions was determined in accordance with ASTM D1938-85.

Resistance to initial tearing

Initial tear resistance in the longitudinal and transverse directions was determined in accordance with ASTM D1004-66.

Ratio of shear coefficient on the inside of the film to the shear coefficient on the outside of the film (i / o)

The ratio of the slip friction coefficient at the intermediate slip on the inside (i) of the film to the slip friction coefficient at the intermediate slip on the outer side of the film (o) was determined according to DIN 53375.

Water vapor permeability

The water vapor permeability was determined in accordance with DIN 53122, Part 2, at a temperature of 37.8 ° C and a relative humidity of 90 percent.

All types of fibers used are listed in the following table, together with their characteristics.

Characteristics of used fibers

Type of fiber material Weighted fiber length diameter (micrometer) Weighted diameter of fiber diameter (micrometer) L / D ratio A cellulose 197 20 10 B cellulose 18 15 1 C cotton 390 16 23 D cotton 510 17 29 E Polyamide 6.6 620 20 30 F wollastonite 66 8 8 G wollastonite 50 7 7

DETAILED DESCRIPTION OF THE INVENTION

The following examples serve to better illustrate and understand the nature of the present invention and do not limit its scope in any way.

Example 1

Fibers comprised between layers of a five-layer foil whose base layer is transparent

A transparent five-layer foil, i.e. j. after coextrusion, the resulting film was removed and cooled on the first take-up roll and the other three rolls, the film was stretched in the longitudinal direction, in the transverse direction, stabilized and heat treated in a corona using the following conditions:

extrusion:

Longitudinal stretching:

Longitudinal extension factor:

Transverse stretching:

Transverse stretching factor: Stabilization:

Corona treatment:

extrusion temperature 250 ° C draw roller temperature 120 ° C

4.5 temperature in heating zone 170 ° C temperature in stretching zone 165 ° C 8 temperature 155 ° C voltage 10 000 volts frequency 10 000 hertz

The base layer of the film comprised essentially only a propylene homopolymer. Either a propylene homopolymer or a propylene-ethylene copolymer was used to produce the film interlayers. Said interlayers contained various fibers in an amount of up to 30% by weight. The topsheet material on both sides of the film was a thermally bondable copolymer. All layers contained commonly used stabilizers and neutralizing agents.

The multilayer film produced in this manner immediately had a surface tension in the range of 40 to 41 milliwtons / meter (top side). The thickness of the films so produced was from about 35 microns to about 43 microns. The thickness of the top layers was in all cases about 0.7 microns; the thickness of the two interlayers was in each case approximately 3 microns. Regardless of the type of fiber used, the foils had a paper-like appearance. The initial tearability of these films was significantly reduced. At initial tearing and further tearing, the foils produced the same sound as tearing paper. The friction coefficient of the films produced in this example was reduced.

Comparative Example 1

For comparison with Example 1, a film was produced whose structure was identical to that of Example 1, except that no fibers were added to the interlayers of the film.

Table 1

Properties of films produced according to Example 1 and Comparative Example 1

Type of fiber used Fiber Quantity (%) D 2.5 C 2.5 B 2.5 A 2.5 Comparative example without fibers Basis weight (g / m ² ) 27.6 27.9 33.2 30.5 34.3 Elastic modulus in longitudinal direction (N / mm ² ) 1700 1700 1900 1700 1900 Transverse modulus of elasticity (N / mm ² ) 4600 4900 5000 4600 5400 Initial tear strength (N) 6.9 7.2 8.0 7.9 9.6 Crack propagation strength, longitudinal direction (mN) 96 124 156 144 164 Crack propagation strength, transverse direction (mN) 44 32 44 80 60 Ratio of shear coefficients i / o 0.35 0.4 0.35 0.3 0.5

Example 2

Fibers contained in the base layer of a five-layer transparent film

The film was produced in the same manner as the film in Example 1. In contrast to Example 1, the fibers in this case were incorporated into the base layer of the film, the interlayers containing no fibers. Accordingly, a transparent five-layer foil, i.e. j. after coextrusion, the resulting film was removed and cooled on the first take-up roll and the other three rolls, the film was stretched in the longitudinal direction, in the transverse direction, stabilized and heat treated in a corona using the following conditions:

extrusion:

Longitudinal stretching:

Longitudinal extension factor:

Transverse stretching:

Transverse stretching factor: Stabilization:

Corona treatment:

extrusion temperature 250 ° C draw roller temperature 114 ° C

4.5 Temperature in heating zone 172 ° C Temperature in stretching zone 160 ° C 8 Temperature 150 ° C Voltage 10,000 Volts Frequency 10,000 Hertz

The multilayer film produced in this manner immediately had a surface tension in the range of 40 to 41 milliwtons / meter (top side). The thickness of the films so produced was from about 38 micrometers to about 42 micrometers. The thickness of the top layers was in all cases about 0.7 microns; the thickness of the two interlayers was in each case approximately 3 microns. Regardless of the type of fibers used, the films of Example 2 had a paper-like appearance. The initial tearability of these films was significantly reduced. At initial tearing and further tearing, the foils produced the same sound as tearing paper. The friction coefficient of the films produced in this example was reduced.

Comparative Example 2

For comparison with Example 2, a film was produced whose structure was identical to that of Example 2, but with no fibers in the base layer.

Table 2

Properties of foils produced according to Example 2 and Comparative Example 2

Type of fiber used Quantity of fibers (%) F 7.5 F 5.0 Comparative example without fibers Basis weight (g / m ² ) 38.1 36.4 34.6 Elastic modulus in longitudinal direction (N / mm ² ) 1700 1800 2000 Transversal modulus of elasticity (N / mm ² ) 2800 3000 3500 Initial tear strength (N) 7.7 8.1 9.4 Crack propagation strength, longitudinal direction (mN) 88 128 124 Crack propagation strength, transverse direction (mN) 40 28 60 Ratio of shear coefficients i / o 0.30 0.32 0.45

Example 3

Fibers contained in interlayers of a five-layer foil with a matt base foil

The film was produced in the same manner as the film in Example 1. In contrast to Example 1, the base layer in this case further contained calcium carbonate and titanium dioxide. Thus, a matt five-layer foil, i.e. a matt five-layer film, has been produced by a corresponding sequence of production steps. j. after coextrusion, the formed film was removed and cooled on the first take-up roll and the other three rolls, the film stretched in the longitudinal direction, in the transverse direction, stabilized and heat treated in a corona, using the following conditions:

SK 287172-6

Ľxtrudo vanie:

Longitudinal stretching:

Longitudinal extension factor:

Transverse stretching:

Transverse stretching factor: Stabilization:

Corona treatment:

extrusion temperature 240 ° C draw roller temperature 114 ° C

4.5 Temperature in heating zone 172 ° C Temperature in stretching zone 160 ° C 8 Temperature 150 ° C Voltage 10,000 Volts Frequency 10,000 Hertz

The multilayer film produced in this manner immediately had a surface tension in the range of 40 to 41 milliwtons / meter (top side). The thickness of the films so produced was from about 32 microns to about 44 microns. The thickness of the top layers was in all cases about 0.7 microns; the thickness of the two interlayers was in each case approximately 3 microns. Regardless of the type of fibers used, all of the films of this example had a similar appearance. The initial tearability of these films was significantly reduced. At initial tearing and further tearing, the foils produced the same sound as tearing paper. The tearing coefficient of the films produced in this example was reduced. Films containing multiple fibers (type F, 15 percent) in the interlayer showed a significantly reduced water vapor permeability (about 50 percent).

Comparative Example 3

For comparison with Example 3, a film was produced whose structure was identical to that of Example 3, but with the exception that no fibers were added to the interlayers of the film.

Table 3

Properties of films produced according to Example 3 and Comparative Example 3

Type of fiber used Fiber Quantity (%) F D C B Comparative example without fibers 15.0 2.5 2.5 2.5 Basis weight (g / nt) 29.7 20.4 26.4 26.3 30.8 Elastic modulus in longitudinal direction (N / mm ² ) 1500 1100 1200 1300 1600 Transverse modulus of elasticity (N / mm ² ) 2400 2200 2300 2300 2900 Initial tear strength (N) 5.2 6.8 6.4 6.7 8.5 Crack propagation strength, longitudinal direction (mN) 82 56 84 68 94 Crack propagation strength, transverse direction (mN) 63 52 36 40 55 Ratio of shear coefficients Vo 0.25 0.35 0.3 0.4 0.55 Water vapor permeability (at 37.8 ° C and 90% humidity) 7.8 - - - 6.8

Example 4

Fibers contained in the base layer of a five-layer foil with the mother base layer

The film was produced in the same manner as the film in Example 2. In contrast to Example 2, the film in this case further contained calcium carbonate and titanium dioxide in the base layer.

Thus, a matt five-layer foil, i.e. a matt five-layer film, has been produced by a corresponding sequence of production steps. j. after coextrusion, the resulting film was removed and cooled on the first take-up roll and the other three rolls, the film was stretched in the longitudinal direction, in the transverse direction, stabilized and heat treated in a corona using the following conditions:

extrusion:

Longitudinal stretching:

Longitudinal extension factor:

Transverse stretching:

Transverse stretching factor: Stabilization:

Corona treatment:

extrusion temperature 245 ° C draw roller temperature 114 ° C

4.5 temperature in heating zone 170 ° C temperature in stretching zone 160 ° C 8 temperature 150 ° C voltage 10 000 volts frequency 10 000 hertz

The multilayer film produced in this manner immediately had a surface tension in the range of 40 to 41 milliwtons / meter (top side). The thickness of the films so produced was from about 40 microns to about 52 microns. The thickness of the top layers was in all cases about 0.7 microns; the thickness of the two interlayers was in each case approximately 3 microns. Regardless of the type of fibers used, all of the films of this example had a similar appearance. The initial tearability of these films was significantly reduced. At initial tearing and further tearing, the foils produced the same sound as tearing paper. The friction coefficient of the films produced in this example was reduced.

Comparative Example 4

For comparison with Example 4, a film was produced whose structure was identical to that of Example 4, but with no fibers added to the base layer of the film.

Table 4

Properties of films produced according to Example 4 and Comparative Example 4

Type of fiber used E Comparative example without Fiber Quantity (%) 1.5 fiber Basis weight (g / m ² ) 30.4 31.1 Elastic modulus in longitudinal direction (N / mm ² ) 1156 1700 Transverse modulus of elasticity (N / mm ² ) 2600 3000 Initial tear strength (N) 7.7 8.6 Crack propagation strength, longitudinal direction (mN) 92 76 Crack propagation strength, transverse direction (mN) 68 52

Example 5

Fibers contained in the base layer and in the interlayer of a five-layer foil with a matt base foil

The film was produced in the same manner as the film of Example 4. In contrast to Example 4, the film in this case contained up to 30% by weight of fibers in the base layer, so that in this case the fibers were contained both in the base layer and in the intermediate layers.

Thus, a matt five-layer foil, i.e. a matt five-layer film, has been produced by a corresponding sequence of production steps. j. after coextrusion, the resulting film was removed and cooled on the first take-up roll and the other three rolls, the film was stretched in the longitudinal direction, in the transverse direction, stabilized and heat treated in a corona using the following conditions:

extrusion:

Longitudinal stretching:

Longitudinal extension factor:

Transverse stretching:

Transverse stretching factor: Stabilization:

Corona treatment:

extrusion temperature 245 ° C draw roller temperature 114 ° C

4.5 temperature in heating zone 170 ° C temperature in stretching zone 160 ° C 8 temperature 150 ° C voltage 10 000 volts frequency 10 000 hertz

The multilayer film produced in this manner immediately had a surface tension in the range of 40 to 41 milliwtons / meter (top side). The thickness of the films so produced was from about 40 micrometers to about 48 micrometers. The thickness of the top layers was in all cases about 0.7 microns; the thickness of the two interlayers was in each case approximately 3 microns. Regardless of the type of fibers used, all of the films of this example had a similar appearance. The initial tearability of these films was significantly reduced. At initial tearing and further tearing, the foils produced the same sound as tearing paper. The friction coefficient of the films produced in this example was reduced.

Table 5

Properties of films produced according to Example 5 and Comparative Example

Type of fiber used F F G G Amount of fibers in the interlayer (%) 7.5 7.5 7.5 7.5 Comparative example without fibers The amount of fibers in the base layer (%) 5.0 2.5 5.0 2.5 Basis weight (g / m ² ) 28.8 29.0 32.9 31.6 29.4 Elastic modulus in longitudinal direction (N / mm ² ) 1100 1300 1200 1400 1500 Transverse modulus of elasticity (N / mm ² ) 1600 2000 1700 2100 2600 Initial tear strength (N) 6.3 6.7 5.9 7.0 8.5 Crack propagation strength, longitudinal direction (mN) 124 116 124 112 100 Crack propagation strength, transverse direction (mN) 232 156 60 64 58 Water vapor permeability (at 37.8 ° C and 90% humidity) 7.3 7.0 7.5 6.8 6.5

Claims (15)

PATENT CLAIMS A biaxially oriented polymeric film comprising at least one layer, characterized in that the layer is a fiber-containing layer which is formed from a thermoplastic polymer and comprises cellulose fibers, cotton fibers, polypropylene fibers, polyethylene fibers, polyester fibers, polyamide fibers, polyimide fibers fibers, wolastonite fibers or fibers consisting of calcium silicate. 2. A biaxially oriented polymeric film comprising at least one layer, wherein the layer is a fiber-containing layer formed of a thermoplastic polymer and comprising natural fibers, polymer fibers or mineral fibers, wherein the mineral fibers are not asbestos fibers or glass fibers. and the thermoplastic polymer is a polyolefin. A film polymer according to claim 2, characterized in that the polyolefin is polypropylene. Foil polymer according to any one of claims 1 to 3, characterized in that the fiber-containing layer comprises from 0.5% by weight to 30% by weight of fibers based on the weight of the layer. Foil polymer according to any one of claims 2 to 4, characterized in that the fibers are cellulose fibers, cotton fibers, polypropylene fibers, polyethylene fibers, polyester fibers, polyamide fibers, polyimide fibers, wollastonite fibers or fibers made of calcium silicate. A film according to any one of claims 1 to 5, characterized in that the fibers have a length ranging from 10 microns to 200 microns and have a diameter ranging from 1.5 microns to 50 microns, wherein the ratio of length to diameters (L) (D) said fibers are in the range of 5 to 30. A film polymer according to any one of claims 1 to 6, characterized in that the fibers have a melting point which is at least 5 ° C higher than the temperature at which the polymer matrix or the polymer matrix-fiber mixture is extruded. A film polymer according to any one of claims 1 to 7, characterized in that the polymer in the fiber-containing layer is polyimide, polyamide, polyester or PVC. A film polymer according to claim 3, characterized in that the polypropylene is an isotactic propylene homopolymer. A film polymer according to any one of claims 1 to 9, characterized in that the film is multilayered, the fiber-containing layer forming the base layer and / or the intermediate layer of the film. 5 A film polymer according to one or more of Claims 1 to 10, characterized in that the base layer and / or the intermediate layer comprises pigments and / or cavity-initiating fillers. Film foil according to claim 11, characterized in that the fiber-containing layer further comprises pigments and / or cavity-initiating fillers. The method of producing a polymeric film according to claims 1 to 12, characterized in that the mixture of thermoplastic polymer and fibers is extruded onto a cooling roller and the resulting preform is heated and stretched in the longitudinal and transverse directions. Use of a polymer film according to any one of claims 1 to 12 as packaging film. Use of a polymer film according to any one of claims 1 to 12 as a marking film. Use of the polymer film according to any one of claims 1 to 12 as a laminating film. Use of the polymer film according to any one of claims 1 to 12 as a metallizable film.