EP2235126A1

EP2235126A1 - Carrier film, in particular for an adhesive tape, and use thereof

Info

Publication number: EP2235126A1
Application number: EP09703455A
Authority: EP
Inventors: Bernhard MÜSSIG; Uwe Michel
Original assignee: Tesa SE
Current assignee: Tesa SE
Priority date: 2008-01-22
Filing date: 2009-01-12
Publication date: 2010-10-06
Also published as: CN101978010A; WO2009092640A1; DE102008005564A1; DE112009000129A5; US20110014449A1; JP2011510143A; CA2712712A1

Abstract

The invention relates to a carrier film, in particular for an adhesive tape, which is stretched monoaxially in the longitudinal direction and contains a layer made of polypropylene, characterized in that the tension of the carrier film in the longitudinal direction at 10% elongation is at least 150 N/mm², preferably at least 200 N/mm², very particularly preferably at least 250 N/mm², the layer contains a polypropylene polymer having a content of olefinic co-monomers of less than 2.5 wt.-%, preferably 0 wt.-%, the layer is not nucleated, and a separating lacquer is applied on one side of the layer.

Description

tesa Aktiengesellschaft Hamburg

description

Carrier film in particular for an adhesive tape and use thereof

The invention relates to a monoaxially stretched carrier film with a layer of polypropylene homopolymer on which a release layer is applied.

A carrier film is a mechanically stable layer for an adhesive tape in roll form or in the form of a label and usually consists of a PVC film, a biaxially stretched polyester or polypropylene film or, rarely, a monoaxially or non-stretched polypropylene film.

Films with high longitudinal strength are usually achieved by stretching extruded film webs of semi-crystalline thermoplastics. This is predominantly a biaxial stretching. In exceptional cases, the films are oriented to further increase the longitudinal tensile strength only in the longitudinal direction. Both commercially available biaxially oriented and monoaxially stretched films based on polypropylene have, however, in contrast to unstretched films from the blown or cast process low tear propagation resistance in the transverse direction. In practice, this leads in the case of injured edges of film or tape (due to blunt blades when cutting or later unintentional injury to the cut edge) easily tearing or tearing of the film or the tape produced therefrom under tensile load.

For high tensile strength and tear resistance requirements, films or adhesive tapes with filaments or nets are made of filaments of glass or plastic reinforced. The production of such Filamentklebebänder is very complex on the system side and thus expensive and prone to failure. In addition to the base film, the filaments and laminating adhesive (or an additional pressure-sensitive adhesive coating) are additionally required, which further increases the price of the products. Further disadvantages of such filament adhesive tapes are low kink resistance, high thickness, unclean cutting edges and lack of weldability and recyclability. The production of such an adhesive tape is described, for example, in US Pat. No. 4,454,192 A1.

DE 21 04 817 A1 describes a method for producing a tape carrier of polyolefin (polyethylene or polypropylene). By stretching in the longitudinal direction, a tensile strength in the longitudinal direction of 320 N / mm ² should be achieved (according to claim 2, no example available). Stretching ratio and stress at 10% elongation are not disclosed.

The subject of EP 0 255 866 A1 is a longitudinally or biaxially oriented polypropylene film. The addition of elastomeric components increases the impact resistance in the transverse direction. However, this measure leads to a deterioration of the tensile strength and the tear propagation resistance in the transverse direction. The stretching ratio in the longitudinal direction is 1: 5.5 to 1: 7. Tensile strengths of 12 to 355 N / mm ^{2 are} achieved. Data on the stresses at 10% strain are not made.

At the end of the 80s, Beiersdorf (Hamburg) sold a tear strip with a reduced tear tendency. This contained an in

Longitudinally stretched carrier film from NOPI (Harrislee), which by

Coextrusion of raw materials of varying toughness has been produced and a

Stretch ratio of 1: 7.5. The tough coextrusion outer layer reduces, on the principle of impact modifiers, the formation of microcracks when cutting products with sharp blades. However, it does not avoid breaks caused by subsequently injured edges (for example, during transport of the roll or the

Application on the cardboard). The outer layer contains 60 wt .-% polypropylene copolymer with about 5 wt .-% of ethylene and to increase the toughness 40 wt .-% SBS Kauschuk, which deteriorates the light resistance and especially to reduced tensile strength (160 N / mm ² ) and reduced stress at 10% elongation (70 N / mm ² ) of the film in Longitudinal leads. The less tough main layer contains 92% by weight of the polypropylene copolymer and 8% by weight of the SBS rubber. The SBS rubber reduces the tear propagation resistance of a monolayer film of pure polypropylene copolymer with the same draw ratio of about 240 N / mm to 70 N / mm.

DE 44 02 444 A1 relates to a tear-resistant adhesive tape based on monoaxially oriented polyethylene. In some respects similar mechanical properties can be achieved as with corresponding polypropylene products. However, polyethylene has a significantly lower heat resistance than polypropylene, which has a detrimental effect both in the production of the adhesive tape (drying of adhesive or other layers in the oven) as well as in later packaging applications as a grip tape, carton sealing tape, tear strips or paperboard reinforcing strips. The adhesive tapes on the cartons often become hot, for example when passing through printing presses or after being filled with hot goods (for example, food). Another disadvantage of (also stretched) polyethylene films compared to polypropylene films is the significantly lower force at 10% elongation. Due to the higher elongation at a given force, the tapes or carton sealing tapes produced therefrom tend to peel off under tensile load, and paperboard reinforcing strips can not prevent the tearing of cartons. The stretch ratio in the longitudinal direction and achievable stresses at 10% elongation are not disclosed. Tensile strengths of 102 to 377 N / mm ^{2 are} achieved.

The draw ratio of commercial monoaxially stretched polypropylene films used as a carrier in an adhesive tape is about 1: 7. One

Stretch ratio of, for example, 1: 7 indicates that a section of the primary film of 1 m length forms a section of 7 m length of the stretched film. Often it will

Stretch ratio also as a quotient of the line speed before drawing and the

Line speed after drawing designated. The numbers used below refer to the stretching.

An adhesive tape with a carrier of monoaxially stretched film can be provided with a release coating (release coating), if it should be easy to unroll. If the stretching ratio is increased in order to increase the stress at 10% elongation, it is found that, starting at a stretching ratio of 1: 8, the film is damaged by a customary release coating based on polyvinyl stearyl carbamate in toluene. The release-coated film surface is sensitive to friction. Rubbing with an eraser on the painted surface will break it down into fine fibers. Fringing of the surface by friction in coating or cutting systems can lead to delamination of the film ("shredding") even when the adhesive tape rolls off.

In practice, cartons are provided with tapes for splicing or tearing and then stacked. When pulling out individual unfolded cartons from the stack, friction against the adhesive tape occurs. Furthermore, there is friction in the processing of the cartons in packaging lines. Such practical friction leads to the detachment of polypropylene fibers from the surface.

Toluene as common solvent for release coatings (release agent) alone has a damaging effect, this is further enhanced by release agents such as polyvinyl stearyl carbamate. The degree of damage increases with increasing stretch ratio (for example 1:10). If you use a silicone-based release coating, the effect is even more serious. The film is even more damaged by silicone than by polyvinyl stearyl carbamate. On the one hand, the damage occurs even at lower stretching ratios than 1: 8, and on the other hand, the damage of the film is observed not only on the side of the coating with release coating, but even on the opposite side, as if the silicone through the film through wandered. If such an adhesive tape is glued and then removed from the pad, it will split the film and thus tape residues.

Commercially available monoaxially stretched polypropylene films for adhesive tapes are made of polypropylene block copolymer having a flexural modulus of about 1200 MPa or a

Mixture made of a harder polypropylene and a soft LLDPE with a similar average flexural modulus. If you try the force at 10% -

Elongation instead of higher draw by using polypropylene with higher

Bending modulus to raise as usual, it is found that even by this measure damage to the film by release coatings occurs. This will look at slides Polypropylene raw materials with a flexural modulus from 1600 MPa very clearly and especially extremely from a flexural modulus of 2000 MPa.

The object of the invention is to provide a carrier film, in particular for an adhesive tape, on the one hand has a very high tensile modulus or a very high stress at 10% elongation in the longitudinal direction, which is not damaged by a release coating in particular by such silicone-based and does not have the mentioned disadvantages of the films of the prior art.

This object is achieved by a film, as characterized in detail in the main claim. Advantageous embodiments of the invention are described in the subclaims. Furthermore, the use of the film according to the invention is encompassed by the inventive concept.

Accordingly, the invention relates to a carrier film, in particular for an adhesive tape which is monoaxially stretched in the longitudinal direction and which contains a layer of polypropylene, wherein • the tension of the carrier film in the longitudinal direction at 10% elongation at least

150 N / mm ² , preferably at least 200 N / mm ² , very particularly preferably at least 250 N / mm ² ,

The layer contains a polypropylene polymer with an olefinic comonomer content of less than 2.5% by weight, preferably 0% by weight, the layer is not nucleated

• and on one side of the layer a release coating is applied.

In the present invention, the described negative effects can be prevented by a layer of polypropylene having at least 97.5% by weight of propylene.

Also, a layer of polyethylene is more resistant to damage by release liners than a layer of polypropylene block copolymer or of a blend of a polypropylene and a polyethylene. Polyethylene, however, hardly contributes to the intended high stresses at low elongation in contrast to a polypropylene polymer according to the invention. There is a foil from a polyethylene layer and a polypropylene coextruded layer, the adhesion of the layers to each other is only weak. By mixing some of the main component of the other into each layer, the adhesion can be improved, but again, polyethylene hardly contributes to the desired longitudinal mechanical properties, and above all, a layer of such a mixture is again susceptible to damage by release coating all at high draft to produce the desired mechanical properties.

The carrier film can be prepared analogously to the relatively simple extrusion process for monoaxially stretched polypropylene films. It has an increased stress at 10% elongation and tensile strengths in the longitudinal direction, which are between those of conventional monoaxially stretched polypropylene films and those of fiber-reinforced filament adhesive tape carriers, but the expensive process for producing filament adhesive tapes can be avoided. The most commonly used polypropylene film for adhesive tapes is PP-BO (biaxially stretched polypropylene film). These show very low stresses at 10% elongation.

To achieve high tensile strengths and high stresses at 1% and 10% elongation, the stretching process conditions should be selected so that the stretch ratio is the maximum technically feasible for the film. According to the invention, the stretch ratio in the longitudinal direction is preferably at least 1: 8, more preferably at least 1: 9.5.

Attempting to achieve high stresses at 1% and 10% elongation by nucleating a conventional film formulation also causes the problem of damage from release coating. In addition, although the addition of a Nucleierungsmasterbatches leads to improved transparency of the still unstretched film, but this is rendered opaque whitish opaque and thus can be produced neither transparent nor in dark shades colored carrier films. The problems can be solved by the fact that the layer of polypropylene polymer underneath the separating lacquer contains no nucleating agent. Accordingly, this represents an advantageous development of the invention. In the following, "no nucleating agent" is understood to mean that the polypropylene polymer does not have a self-nucleating property due to the polymer composition, such as for example For example, by modification with 4,4'-oxydibenzenesulfonyl azide, nor that the manufacturer adds a nucleating agent in the additization of the polypropylene polymer prior to granulation, or adds a nucleating agent in the preparation of the inventive film, for example, in the form of a masterbatch.

It is believed that the effect of the nucleating agent is that the semi-crystalline polymer forms a different fiber structure during stretching than in the presence of a nucleating agent. It appears that the fiber interstices absorb the release coating, which then permanently causes a separation effect between the fibers, since the solvent causes no damage.

A non-nucleated polypropylene layer can apparently absorb the release coating little if at all.

As a further influencing factor, the content of olefinic comonomer in the polypropylene polymer is found. The content of comonomer is less than

2.5 wt .-%, preferably 0 wt .-%. The latter means that a real

Polypropylene homopolymer is present.

For biaxially stretched polypropylene films and polypropylene are used, which are referred to according to data sheet as homopolymers, but for better processability contain about 1 to 2 wt .-% of ethylene and therefore in the scientific sense actually are copolymers.

Examples of olefinic comonomers are ethylene, butylene and octene. It is assumed that copolymers of propylene in addition to the largely crystalline polypropylene phase form an amorphous elastomer phase, for example, from EPM rubber. If the proportion of comonomer is high, the volume fraction of the amorphous phase increases. It is known to those skilled in the art that it is easier to dissolve by solvents such as toluene than the crystalline regions. For a stretched polypropylene copolymer or terpolymer film, therefore, there should be solvent-sensitive amorphous interstices between the crystalline polypropylene fibers which can receive and pass through the release coating. The person skilled in the art had assumed that a polypropylene homopolymer behaves particularly brittle because of the high degree of hardness and therefore a PP block copolymer or a mixture of a polypropylene and a toughener is less favorable than LLDPE in terms of damage to the surface by release coatings , If further components are present in too large amounts in the layer of polypropylene polymer, these have a negative effect on the resistance to release coatings. This applies, for example, to tougheners such as LLDPE (LLDPE) or SBS rubber, which are commonly used in monoaxially stretched polypropylene block copolymer adhesive films. Therefore, the layer preferably contains less than 10 wt .-%, more preferably less than 5 wt .-%, most preferably no polymers having a content of propylene of less than 80 wt .-%, such as PE-LLD. According to a further preferred embodiment of the invention, the content of non-thermoplastic components, such as, for example, fibers, fillers, pigments or antiblocking agents, is less than 5% by weight, more preferably less than 1% by weight, most particularly because of the required resistance to release coatings preferably no non-thermoplastic components are included. In particular, the carrier film preferably contains no carbon nanotubes.

In order to optimize the mechanical properties of the carrier film, at least one coextrusion layer is applied in addition to the layer of the polypropylene polymer according to the invention on the side facing away from the release coating (release coating).

The layer preferably contains a polypropylene which also preferably has a flexural modulus of at least 1600 MPa, more preferably at least 2000 MPa. The polypropylene of the layer is preferably predominantly isotactic. The melt index should also be in the range suitable for flat film extrusion. The melt index should be between 0.3 and 15 g / 10 min, preferably in the range of 0.8 and 5 g / 10 min (measured at 230 ° C / 2.16 kg). In order to achieve the highest possible values of stresses at 1% and 10% elongation and of tensile strengths, the use of highly isotactic polypropylene is advantageous.

In a multilayer structure, the thickness of the layer is preferably 3 to 20%, more preferably 5 to 10% of the total thickness of the film. In this embodiment, the layer serves to protect a coextrusion layer relevant for the mechanical properties of the film from damage by a release coating. In addition to the polymers, the layer or layers may contain additives such as antioxidants, light stabilizers, antiblocking agents, lubricants and processing aids, fillers, dyes and / or pigments.

The carrier film and an adhesive tape produced using the carrier film has a stress at 10% elongation in the longitudinal direction (machine direction) of at least 150 N / mm ² , preferably at least 200 N / mm ² , more preferably at least 250 N / mm ² , In a preferred embodiment, even voltages of at least 300 N / mm ² can be achieved.

In a preferred embodiment, the carrier film or an adhesive tape produced using the carrier film in the longitudinal direction (machine direction) has a stress at 1% elongation of at least 20 N / mm ² , preferably at least 40 N / mm ² and / or a tensile strength of at least 300 N / mm ² , preferably at least 350 N / mm ² . The tear propagation resistance in the transverse direction should preferably reach at least 80 N / mm, in particular at least 220 N / mm. To calculate strength values, the width-related force values are divided by the thickness. In the case of a determination of the strength values on the adhesive tape, the thickness is not based on the total thickness of the adhesive tape but only on the carrier film.

The thickness of the carrier film is preferably between 25 and 200 .mu.m, particularly preferably between 40 and 140 .mu.m, very particularly preferably between 50 and 90 .mu.m.

The carrier film preferably has no fin structures on the surfaces, since they deteriorate the adhesion during the stretching process and do not permit homogeneous stretching. If the film is constructed by multilayer coextrusion, according to a preferred embodiment of the invention it also has no rib structures in the interior, but plane-parallel oriented layers, so that no complicated and trouble-prone nozzle must be provided.

The film may be modified by lamination, embossing or radiation treatment. The films can be provided with surface treatments. These are, for example, for adhesion promotion corona, flame, fluorine or plasma treatment or on the Separating paint side facing coatings of solutions or dispersions or liquid radiation-curable materials.

The carrier film comprises a release varnish (also called release layer, release or non-stick coating) on the layer, for example those made of silicone, acrylates (for example Primal® 205), stearyl compounds such as polyvinyl stearyl carbamate or chromium stearate complexes (for example Quilon® C) or from reaction products from maleic anhydride copolymers and stearylamine. Preference is given to a release coating based on silicone. The silicone can be applied solvent-free or solvent-borne and be crosslinked by radiation, a condensation or addition reaction, or physically (for example, by a block structure).

Release coatings serve to make an adhesive tape easy to unroll, in order to avoid a high force and / or strain of the wearer. The latter can lead to detachment of the adhesive tape by the stretched carrier shrinks back after the bonding of the tape.

The carrier film according to the invention can be used particularly advantageously in an adhesive tape by applying an adhesive to the carrier film on one side.

As adhesive tape according to the invention a film with a self-adhesive or a heat-activated adhesive layer is preferred. Preferably, however, they are not sealable adhesives but are pressure-sensitive adhesives. For the adhesive tape application, the carrier film is coated on one side with pressure-sensitive adhesive as a solution or dispersion or 100% (for example from the melt) or by coextrusion with the carrier film. The adhesive layer is located on the film side, which does not have the release coating. The adhesive layer can be crosslinked by heat or high-energy radiation and, if necessary, covered with release film or release paper. Suitable pressure-sensitive adhesives are in particular pressure-sensitive adhesives based on acrylate, natural rubber, thermoplastic styrene block copolymer or silicone.

For the purposes of this invention, the general term "adhesive tape" encompasses all flat structures such as films or film sections which are expanded in two dimensions, tapes of extended length and limited width, strip sections and the like, and ultimately also diecuts or labels. To optimize the properties, the self-adhesive composition used can be blended with one or more additives, such as tackifiers (resins), plasticizers, fillers, pigments, UV absorbers, light stabilizers, aging inhibitors, crosslinking agents, crosslinking promoters or elastomers.

Suitable elastomers for blending are, for example, EPDM or EPM rubber, polyisobutylene, butyl rubber, ethylene-vinyl acetate, hydrogenated block copolymers of dienes (for example by hydrogenation of SBR, cSBR, BAN, NBR, SBS, SIS or IR; Example known as SEPS and SEBS) or acrylate copolymers such as ACM.

Tackifiers are, for example, hydrocarbon resins (for example, unsaturated C ₅ or C ₇ monomers), terpene-phenolic resins, terpene resins from raw materials such as α- or β-pinene, aromatic resins such as cumarone-indene resins or resins of styrene or α-methylstyrene such as rosin and its derivatives such as disproportionated, dimerized or esterified resins, whereby glycols, glycerol or pentaerythritol can be used. Particularly suitable are age-stable resins without olefinic double bond such as hydrogenated resins.

Suitable fillers and pigments are, for example, carbon black, titanium dioxide, calcium carbonate, zinc carbonate, zinc oxide, silicates or silicic acid.

Suitable UV absorbers, light stabilizers and aging inhibitors for the adhesives are those which are listed in this document for the stabilization of the film.

Suitable plasticizers are, for example, aliphatic, cycloaliphatic and aromatic mineral oils, di- or poly-esters of phthalic acid, trimellitic acid or adipic acid, liquid rubbers (for example nitrile or polyisoprene rubbers), liquid polymers of butene and / or isobutene, acrylic esters, polyvinyl ethers, liquid and soft resins based on the raw materials to adhesive resins, wool wax and other waxes or liquid silicones.

Crosslinking agents are, for example, phenolic resins or halogenated phenolic resins, melamine and formaldehyde resins. Suitable crosslinking promoters are, for example Maleimides, allyl esters such as triallyl cyanurate, polyfunctional esters of acrylic and methacrylic acid.

According to preferred embodiments, the pressure-sensitive adhesive contains bright and transparent raw materials. Particularly preferred are acrylic pressure-sensitive adhesives (for example as a dispersion) or pressure-sensitive adhesives of styrene block copolymer and resin (for example as are customary for hot melt pressure sensitive adhesives).

The coating thickness with adhesive is preferably in the range of 18 to 50 gg // mm ²² ,, 2222 iinnssbbeessoonnddeerree bbiiss 29 g / m ^2. The width of the adhesive tape rolls is preferably in the range of 2 to 60 mm.

Such an adhesive tape is suitable for reinforcing cardboard, in particular in the area of punched holes, as tear strips for cardboard boxes, as a carrying handle, for securing pallets and for bundling objects. Such items are for example tubes, profiles or stacked boxes (strapping application).

In comparison with the film from EP 0 353 907 A1, the carrier film is produced in-line on a system in only two steps (extrusion, stretching) and additionally has much higher tear propagation resistances in the transverse direction (about 300 N / cm at 70 °) μm thickness).

Test Methods

Thickness: DIN 53370

Tensile strength: DIN 53455-7-5 in longitudinal direction Tension 1% or 10% elongation: DIN 53455-7-5 in longitudinal direction Elongation at break: DIN 53455-7-5 in longitudinal direction Melt index: DIN 53735

• The melt index "Melt Flow Ratio" (MFR) is measured according to DIN 53,735th For polyethylenes melt indices are usually indicated in g / 10 min at 190 ⁰ C and a weight of 2.16 kg, according to polypropylenes, but at a temperature of 230 ⁰ C. flexural modulus (flexural modulus): ASTM D 790 A Density: ASTM D 792

Crystallite melting point: Determination by DSC according to ISO 3146 Nomenclature of plastics: ISO 1043-1 Friction test: »10 strokes with an eraser Edding A 20 with a rounded corner

(Curve radius = 5 mm) in the machine direction with a pressure of 5 kiloponds on the release coated side. Rating: pass = no abrasion, fail = fibers are rubbed out of the surface Adhesive data: AFERA 4001 according to DIN EN 1939

In the following, the invention will be explained with reference to examples, without thereby restricting them.

Examples

raw materials

Dow 7C06:

PP-C MFI 1, 5 g / 10 min, non-nucleated, flexural modulus 1280 MPa, crystallite melting point 164 ⁰ C (Dow Chemical)

Dow Inspire 404.01: Polypropylene, MFI min 3 g / 10, nucleated, flexural modulus 2068 MPa, nucleated with a polymeric nucleating agent corresponding to US 2003/195300 A1, crystallite melting point 164 ⁰ C (Dow Chemical)

PP 3281: PP-H, MFI 1, 1 g / 10 min, non-nucleated, density 0.905 g / cm ^3, flexural modulus 1380 MPa, crystallite melting point 165 ⁰ C (Atofina)

Moplen HP 556 E:

PP-H, non-nucleated, MFI 0.8 g / 10 min, density 0.905 g / cm, flexural modulus 1700 MPa, crystalline melting point 162 ⁰ C (Basell) Moplen HP 501 D:

Copolymer with 1, 5 wt .-% ethylene, MFI 0.7 g / 10 min, not nucleated, flexural modulus 1450

MPa, crystalline melting point 161 ⁰ C (Basell)

HB 205 TF:

PP-H, MFI 0.9 g / 10 min, density 0.905 g / cm ^3, flexural modulus 1200 MPa, crystallite melting point 163 ⁰ C (Borealis)

Dowlex 2032: PE-LLD (random copolymer of ethylene with 1-octene), MFI min 2.0 g / 10 min, density of 0.9260 g / cm ^3, crystallite melting point 124 ⁰ C (Dow Chemical)

Remainder yellow HG AE 30:

PP color masterbatch with translucent pigment (Clariant masterbatches)

ADK STAB NA-1 1 UH: Nucleic Acid (Adeka Palamarole)

Release Coat RA95D: PVSC = polyvinyl stearyl carbamate (k + k chemistry)

Dehesive 940A:

Silicone solution (Wacker Chemical)

Crosslinker V24:

Crosslinker (Wacker Chemical)

Catalyst OL:

Catalyst (Wacker Chemical)

example 1

A two-layer film is coextruded on a single-flute single-flute extrusion die with flexible die lip, followed by chill roll station and one-stage Short-gap stretching unit. The coextruded layer is composed of Inspire D 404.01 and the layer of PP 3281. The die temperature is 235 ⁰ C. The stretch ratio is 1: 10th

The film is corona pretreated on both sides, coated on the layer according to the invention with a 0.5% strength solution of Release Coat RA95D in toluene as release and dried. The adhesive is from 42 wt .-% SIS elastomer, 20 wt .-% pentaerythritol ester of hydrogenated rosin, 37 wt .-% of a C ₅ hydrocarbyl resin having a R & B value of 85 ⁰ C and 1 wt .-% Antioxidant Irganox® 1010 melt-mixed and applied at 150 ⁰ C with a nozzle on the underside of the film. Subsequently, the tape is wound to the mother roll and cut for further testing in 15 mm width.

Adhesive data: • Adhesion to steel 2.2 N / cm

• Unwinding force at 0.3 m / min 1, 1 N / cm

• Ground application 23 g / m ² .

Test results: Film properties: Carrier thickness after stretching 75 μm Thickness of the coextrusion layer 70 μm Thickness of the layer 5 μm Stress at 1% elongation 65 N / mm ² Stress at 10% elongation 280 N / mm ² Tensile strength 331100 N / mm ² Elongation at break 8%

Friction test pass

Example 2

The film is prepared analogously to Example 1, but the stretching ratio is set at 1: 8. As raw materials for the coextrusion layer is a mixture of 98.9 wt .-% Moplen HP 556 E and 1, 1 wt .-% Remafingelb HG AE 30 used. The layer consists of PP 3281.

The film is corona pretreated on both sides and then provided on the top with a silicone release varnish. It consists of 21,800 parts by weight of heptane, 3126 parts by weight of Dehesive 940A, 8 parts by weight of methylbutynol, 23 parts by weight of Crosslinker V24 and 31 parts by weight of Catalyst OL. The underside is provided with a primer of natural rubber, cyclo rubber and 4,4'-diisocyanato-diphenylmethane. The adhesive is from 40 wt .-% natural rubber SMRL (Mooney 70), 10 wt .-% of titanium dioxide, 37 wt .-% of a C ₅ - hydrocarbon resin having a R & B value of 95 ⁰ C and 1 wt .-% antioxidant Vulkanox ® BKF dissolved in hexane in a kneader. The 20 wt .-% adhesive is applied with a brush the primed film underside and dried at 115 ⁰ C. Subsequently, the tape is wound to the mother roll and cut for further testing in 15 mm width.

Adhesive data:

• Adhesion to steel 1, 9 N / cm

• Unwinding force at 0.3 m / min 0.2 N / cm • Mass application 24 g / m ² .

Test results: film properties:

Carrier thickness after stretching 64 μm

Thickness of Coextrusion Layer 60 μm Thickness of Layer 4 μm

Stress at 1% elongation 52 N / mm ²

Stress at 10% strain 306 N / mm ²

Tensile strength 330 N / mm ²

Elongation at break 20%

Friction test pass Example 3

The film is produced analogously to Example 1, the layer and the coextrusion layer consist of Moplen HP 501 D, the draw ratio is 1: 9.8.

Test results: Film properties: Carrier thickness after stretching 35 μm Thickness of the coextrusion layer approx. 32 μm Thickness of the layer approx. 3 μm Stress at 1% elongation 60 N / mm ² Stress at 10% elongation 357 N / mm ² Tensile strength 502 N / mm ² elongation at break 17%

A) The film is corona pretreated on both sides and then further processed according to Example 2.

Result friction test: fail (silicone).

B) The film is corona pretreated on both sides and then further processed according to Example 1. Result friction test: pass (polyvinyl stearyl carbamate).

This film is also according to the invention. It passes the friction test with a polyvinyl stearyl carbamate-based release, even though the friction test with a silicone-based release (for the reasons outlined above) fails.

Example 4

The film is produced analogously to Example 1, the coextrusion layer consists of Moplen HP 556 E, the draw ratio is 1: 9.7. Corona treatment and coating are carried out as in Example 2. Test results: film properties:

Carrier thickness after stretching 64 μm

Thickness of coextrusion layer 60 μm

Thickness of the layer 4 microns

Stress at 1% strain 68 N / mm ²

Stress at 10% elongation 290 N / mm ²

Tensile strength 300 N / mm ²

Friction test pass

Example 5

The film is prepared analogously to Example 1, but the stretching ratio is set at 1: 8 and the stretching roller temperature is reduced. The raw materials used for the coextrusion layer are a mixture of 98.9 parts by weight of Moplen HP 501 D, 0.9 part by weight of remainder yellow HG AE 30 and 0.2 part by weight of ADK STAB NA-11 UH. The layer according to the invention consists of Moplen HP 556 E.

Test results: film properties:

Carrier thickness after stretching 64 μm

Thickness of coextrusion layer 60 μm

Thickness of the layer 4 microns

Stress at 1% strain 36 N / mm ²

Stress at 10% elongation 256 N / mm ²

Tensile strength 290 N / mm ²

Elongation at break 30%

Friction test pass Comparative Example 1

The production of film and coating is carried out according to Example 1, but the film is without a layer. The release is therefore applied to the layer of lnspire D 404.01.

Test results: film properties:

Carrier thickness after stretching 70 μm

Stress at 1% strain 68N / mm ²

Stress at 10% elongation 290 N / mm ²

Tensile strength 317 N / mm ²

Elongation at break 7%

Friction test fail

Comparative Example 2

The film is produced in accordance with Example 5, but the layer has the same composition as the coextrusion layer namely a mixture of 98.9 parts by weight of Moplen HP 501 D, 0.9 parts by weight of remainder yellow HG AE 30 and 0.2 Parts by weight ADK STAB NA-11 UH

Test results: film properties:

Carrier thickness after stretching 65 μm

Thickness of coextrusion layer 60 μm

Thickness of the layer 5 microns

Stress at 1% strain 37 N / mm ²

Stress at 10% strain 258 N / mm ²

Tensile strength 310 N / mm ²

Breaking elongation 32% A) The film is corona pretreated on both sides and then further processed according to Example 2.

Result friction test: fail (silicone).

B) The film is corona pretreated on both sides and then further processed according to Example 1.

Result friction test: fail (polyvinyl stearyl carbamate).

Comparative Example 3

A film is prepared analogously to Comparative Example 1 from 99.8 wt .-% Dow 7C06 and 0.2 wt .-% ADK STAB NA-1 1 UH with a stretch ratio of 1: 6.3.

test results:

Carrier thickness after stretching 80 μm

Stress at 1% strain 26 N / mm ²

Stress at 10% elongation 162 N / mm ²

Tensile strength of 245 N / mm ²

Elongation at break 21%

Friction test fail

Comparative Example 4

A film is prepared analogously to Comparative Example 3 from Dow 7C06 with a draw ratio of 1: 6.1 with a slightly higher stretch roll temperature. Corona treatment and coating are carried out as in Example 1.

test results:

Carrier thickness after stretching 80 μm

Stress at 1% strain 19 N / mm ²

Stress at 10% elongation 142 N / mm ²

Tensile strength 247 N / mm ² Elongation at break 27%

Friction test pass

The positive result of the friction test is bought with weaker mechanical data.

Comparative Example 5

The film is produced according to Example 1, but the layer consists of Dow 7C06. Corona treatment and coating are carried out as in Example 2.

test results:

Film properties: Carrier thickness after stretching 75 μm Thickness of the coextrusion layer 70 μm Thickness of the layer 5 μm Stress at 1% elongation 60 N / mm ² Stress at 10% elongation 270 N / mm ² Tensile strength 300 N / mm ² Elongation at break 1 1%

Friction test fail

Comparative Example 6

The film is produced according to Comparative Example 4, the draw ratio is 1: 7.5, and the film consists of conventional polypropylene homopolymer HB 205 TF. Corona treatment and coating are carried out as in Example 1.

Test results: Film properties: Carrier thickness after stretching 55 μm Stress at 1% strain 25 N / mm ²

Stress at 10% strain 130 N / mm ²

Tensile strength 370 N / mm ²

Elongation at break 40%

Friction test pass The positive result of the friction test is paid for with weaker mechanical data (stress at 1% and 10% elongation).

Comparative Example 7

The film is produced according to Comparative Example 4, the draw ratio is 1: 7.5, and the film consists of 85 wt .-% HB 205 TF and 15 wt .-%. Dowlex 2032.

test results:

Film properties:

Carrier thickness after stretching 40 μm

Stress at 1% strain 18 N / mm ²

Stress at 10% strain 88 N / mm ²

Tensile strength 245 N / mm ²

Elongation at break 60%

A) The film is corona pretreated on both sides and then further processed according to Example 2. Result friction test: fail (silicone).

Claims

claims

1. carrier film, in particular for an adhesive tape which is monoaxially stretched in the longitudinal direction and which contains a layer of polypropylene, characterized in that the tension of the carrier film in the longitudinal direction at 10% elongation at least 150 N / mm ² , preferably at least 200 N / mm ² , most preferably at least

250 N / mm ² , the layer contains a polypropylene polymer having an olefinic comonomer content of less than 2.5% by weight, preferably 0% by weight, the layer is not nucleated and a release coating on one side of the layer is applied.

2. Carrier film according to claim 1, characterized in that in the layer less than 10 wt .-%, preferably less than 5 wt .-% polymers are contained with a content of propylene of less than 80 wt .-% or that particularly preferably 0 wt .-% of polymers having a content of propylene of less than 80 wt .-% are included.

3. Carrier film according to claim 1 or 2, characterized in that the layer has a content of non-thermoplastic components of less than 5 wt .-%, preferably less than 1 wt .-% or that more preferably 0 wt .-% non-thermoplastic components are.

4. carrier film according to at least one of claims 1 to 3, characterized in that the carrier film contains no carbon nanotubes.

5. carrier film according to at least one of the preceding claims, the carrier film

In the longitudinal direction, a stretch ratio of at least 1: 8, preferably at least 1: 9.5, In the longitudinal direction, a tensile strength of at least 300 N / mm ² , preferably at least 350 N / mm ² and / or

• has a stress at 1% elongation of at least 20 N / mm ² , preferably at least 40 N / mm ² in the longitudinal direction.

6. carrier film according to at least one of the preceding claims, characterized in that the polypropylene polymer of the layer has a melt index of 0.3 to 15 g / 10 min, preferably from 0.8 to 5 g / 10 min and / or a flexural modulus of at least 1600th MPa, preferably at least 2000 MPa.

7. carrier film according to at least one of the preceding claims, characterized in that the carrier film has a thickness of 25 to 200 .mu.m, preferably 30 to 140 .mu.m, more preferably 50 to 90 microns.

8. carrier film according to at least one of the preceding claims, characterized in that the layer on the opposite side of the release coating has a coextrusion layer, which preferably contains a polypropylene, which preferably has a flexural modulus of at least 1600 MPa, more preferably at least 2000 MPa and / or that is nucleed.

9. carrier film according to claim 8, characterized in that the thickness of the layer is 3 to 20%, preferably 5 to 10% of the total film thickness.

10. Carrier film according to at least one of the preceding claims, characterized in that the release coating contains polyvinyl stearyl carbamate or preferably silicone.

1 1. Use of a carrier film according to at least one of the preceding claims as a carrier film in an adhesive tape.

12. Use of a carrier film according to at least one of the preceding claims as a carrier film in an adhesive tape in particular for reinforcing cardboard in particular in the field of punching, as tear strips for cartons, as a carrying handle for pallet securing or for bundling objects.