EP1675882A1

EP1675882A1 - Calendered wrapping foil

Info

Publication number: EP1675882A1
Application number: EP04787158A
Authority: EP
Inventors: Bernhard MÜSSIG
Original assignee: Tesa SE
Current assignee: Tesa SE
Priority date: 2003-10-14
Filing date: 2004-09-16
Publication date: 2006-07-05
Also published as: JP2007510013A; DE10348474A1; MXPA06004107A; US20070074893A1; WO2005037878A1

Abstract

Disclosed is halogen-free calendered, especially flame-resistant polyolefin wrapping foil which is characterized in that the melt-flow index of the polyolefin is less than 5 g/10 min, preferably less than 1 g/10 min, and particularly less than .7 g/10 min.

Description

Calendered wrapping film

The present invention relates to a calendered halogen-free wrapping film made of polyolefin, which is optionally provided with a pressure-sensitive adhesive coating which is used, for example, for wrapping ventilation ducts in air conditioning systems, wires or cables and which is particularly suitable for cable harnesses in vehicles or field coils for picture tubes. The wrapping film is used for bundling, isolating, marking, sealing or protecting. The invention further comprises methods for producing the film according to the invention.

Cable wrapping tapes and insulating tapes usually consist of plasticized PVC film with a one-sided adhesive coating. There is an increasing desire to eliminate disadvantages of these products.

The plasticizers of conventional insulating tapes and cable winding tapes gradually evaporate, which leads to a health burden, in particular the commonly used DOP is of concern. Furthermore, the vapors in motor vehicles are deposited on the windows, which worsens visibility (and therefore considerably driving safety) and is referred to as fogging (DIN 75201) by a specialist. In the event of even greater evaporation due to higher temperatures, for example in the interior of vehicles or in the case of insulating tapes in electrical devices, the wrapping film becomes brittle as a result of the loss of plasticizer.

Plasticizers worsen the fire behavior of pure PVC, which is partially compensated for by the addition of antimony compounds, which are very toxic, or by the use of plasticizers containing chlorine or phosphorus. Against the background of the discussion about the incineration of plastic waste, for example shredder waste from vehicle recycling, there is a trend towards reducing the halogen content and thus the generation of dioxins. For this reason, the wall thicknesses of the cable insulation and the thickness of the PVC film for the tapes used for wrapping are reduced. The usual thickness of PVC foils for winding tapes is 85 to 200 μm. Below 85 μm there are considerable problems in the calendering process, so that such products with a reduced PVC content are hardly available.

The usual vibro strips contain stabilizers based on toxic heavy metals, mostly lead, less often cadmium or barium.

State of the art for bandaging cable sets are wrapping foils with and without adhesive coating, which consist of a PVC carrier material that is flexibly adjusted by incorporating considerable amounts (30 to 40% by weight) of plasticizer. The backing material is usually coated on one side with a self-adhesive based on SBR rubber. Significant shortcomings of these PVC tapes are their low aging stability, the emigration and evaporation of plasticizers, their high halogen content and high smoke density in the event of a fire. Typical soft PVC adhesive tapes are described in JP 10 001 583 A1, JP 05 250 947 A1, JP 2000 198 895 A1 and JP 2000 200 515 A1. In order to achieve a higher flame resistance of the soft PVC materials, the highly toxic compound antimony oxide is usually used, as described for example in JP 10 001 583 A1.

Efforts have been made to use woven or non-woven fabrics instead of soft PVC film, but the resulting products are used only little in practice because they are relatively expensive and can be handled (for example by hand tearability, elastic resilience) and under conditions of use (for example resistance to operating fluids, electrical properties) differ greatly from the usual products, whereby in the following the thickness is of particular importance, since the diameter of cable harnesses increases due to the increasing number of consumers. Some examples of textile adhesive tapes:

In DE 200 22 272 U1 _. EP 1 123 958 A1 and WO 99/61541 A1 describe adhesive tapes made of a woven or non-woven backing material. These materials are characterized by a very high tear resistance. However, this has the disadvantage that these adhesive tapes cannot be torn off by hand without the use of scissors or knives. Elasticity and flexibility are two of the main requirements for winding tapes in order to be able to produce wrinkle-free and flexible cable harnesses. Furthermore, these materials do not meet the relevant fire protection standards such as FMVSS 302. Improved fire properties can only be achieved using halogen-containing flame retardants or polymers as described in US Pat. No. 4,992,331 A1.

Such thick nonwovens make the cable harnesses even thicker and less flexible than classic PVC tapes, even if this has a positive effect on sound insulation, which is only an advantage in some areas of cable harnesses. Nonwovens are not very stretchy and have practically no resilience. This is important because thin branches of cable harnesses must be wound tightly so that they do not hang limply during installation and can be easily positioned in front of the clips and the connectors. Another disadvantage of textile adhesive tapes is the low breakdown voltage of approx. 1 kV, because only the adhesive layer insulates. Foil tapes, on the other hand, are above 5 kV, they are good voltage resistant.

Wrapping foils and cable insulation made from thermoplastic polyester are being used on a trial basis to manufacture cable harnesses. These have significant shortcomings with regard to their flexibility, processability, aging resistance or compatibility with the cable materials. However, the most serious disadvantage of polyester in addition to flammability is the considerable sensitivity to hydrolysis, so that it cannot be used in automobiles for safety reasons.

DE 100 02 180 A1, JP 10 149 725 A1, JP 09 208 906 A1 and JP 05 017 727 A1 describe the use of halogen-free thermoplastic polyester carrier films. JP 07 150 126 A1 describes a flame-retardant wrapping film made of a polyester carrier film which contains a brominated flame retardant.

The patent literature also describes winding tapes made of polyolefins. However, these are highly flammable or contain halogen-containing flame retardants. In addition, the materials made from ethylene copolymers have too low a softening point (they tend to melt when trying to test for heat aging resistance) and the material is too inflexible when using polypropylene polymers. The winding tapes described were produced by extrusion processes, usually by the cast process (T-die) and rarely by blow extrusion. The products described therefore have an increased shrinkage compared to calendered or cast films, which can lead to the telescoping of the rolls. For manufacturers of PVC wrapping tapes, the task when changing to new halogen-free wrapping tapes also has to take full advantage of the existing calender systems. The proposed solutions for halogen-free winding tapes not only have a number of technical defects, but do not offer a solution for the existing calender systems.

WO 00 71634 A1 describes a winding adhesive tape whose film consists of an ethylene copolymer as the base material. The carrier film contains the halogen-containing flame retardant decabromodiphenyl oxide. The film softens below a temperature of 95 ° C, but the normal usage temperature is often above 100 ° C or briefly even above 130 ° C, which is not uncommon when used inside the engine.

WO 97/05206 A1 describes a halogen-free winding adhesive tape, the backing film of which consists of a polymer blend of low-density polyethylene and an ethylene / vinyl acetate or ethylene / acrylate copolymer. 20 to 50% by weight of aluminum hydroxide or ammonium polyphosphate are used as flame retardants. A major disadvantage of the carrier film is again the low softening temperature. To counteract this, the use of silane crosslinking is described. However, this networking method only leads to very unevenly cross-linked material, so that in practice no stable production process or uniform quality of the product can be realized.

Analogous problems of the lack of heat resistance occur with the electrical adhesive tapes described in WO 99/35202 A1 and US 5,498,476 A1. A blend of EPDM and EVA in combination with ethylenediamine phosphate as a flame retardant is described as the carrier film material. Like ammonium polyphosphate, this has a high sensitivity to hydrolysis. In combination with EVA also occurs embrittlement upon aging. Use on common cables made of polyolefin and aluminum or magnesium hydroxide leads to poor compatibility. In addition, the fire behavior of such cable harnesses is poor, since these metal hydroxides with phosphorus compounds, as explained below, have an antagonistic effect. The insulating tapes described are too thick and too stiff for cable harness tapes.

Attempts to solve the dilemma of too low a softening temperature, flexibility and freedom from halogen are described in the following patents.

EP 0 953 599 A1 claims a polymer mixture of LLDPE and EVA for applications as cable insulation and as a film material. A combination of magnesium hydroxide with a special surface and red phosphorus is described as a flame retardant, but softening at a relatively low temperature is accepted.

A very similar combination is described in EP 1 097 976 A1. Here, however, a PP polymer is used instead of the LLDPE to improve the heat resistance, which has a higher softening temperature. The disadvantage is the resulting low flexibility. When mixing with EVA or EEA, it is claimed that the film has sufficient flexibility. However, it is known to the person skilled in the art from the literature that these polymers are blended with polypropylene to improve flame retardancy. The products described have a film thickness of 0.2 mm; this thickness alone rules out flexibility in the case of filled polyolefin films, since the third power depends on the thickness. With the extremely low melt indices of the polyolefins used, as is known to the person skilled in the art, the extrusion process described can hardly be carried out on a production system, especially not for a practical thin film, and certainly not when used in combination with the high ones described Amounts of filler.

Both approaches build on the well-known synergistic flame retardant effect of red phosphorus with magnesium hydroxide. However, the use of elemental phosphorus has considerable disadvantages and dangers. During processing, malodorous and highly toxic phosphine is released. Another disadvantage arises from the formation of very dense white smoke in the event of a fire. In addition, only brown up black products can be produced, but wrapping foils are used in a wide range of colors for color coding purposes.

DE 203 06 801 U describes a winding tape made of polyurethane, such a product is far too expensive for the usual applications described above. There is no evidence of the use of anti-aging agents or magnesium hydroxide.

Despite the disadvantages mentioned, the cited prior art patents do not list any films which also solve other requirements such as hand tearability, heat resistance, compatibility with polyolefin cable insulation or sufficient unwinding force. In addition, the processability in film production processes, high fogging value and the dielectric strength remain questionable. A film that could be produced using the calendering process was not found.

The object of the invention therefore remains to find a solution for a calendered wrapping film which combines the mechanical properties (such as elasticity, flexibility, hand tearability) of PVC wrapping tapes with the halogen-free nature of textile wrapping tapes and also has sufficient heat aging resistance, a large-scale producibility of the film should be ensured on a soft PVC film system and a high dielectric strength and a high fogging value is desirable in some applications. It is a further object of the invention to provide calenderable, halogen-free wrapping films which enable particularly safe and rapid wrapping, in particular of wires and cables, for marking, protecting, isolating, sealing or bundling, the disadvantages of the prior art do not occur or at least not to the extent.

With the increasing complexity of electronics and the increasing number of electrical consumers in automobiles, the wiring harnesses are becoming increasingly complex. With increasing cross-sections of the cable harnesses, the inductive heating increases while the heat dissipation decreases. This increases the requirements for the heat resistance of the materials used. The PVC materials used as standard for the wrapping tapes reach their limits here. There is therefore also the task of adding polypropylene copolymers with additive combinations find which not only achieve the heat resistance of PVC, but even surpass it.

This problem is solved by a wrapping film as set out in the main claim. The subclaims relate to advantageous developments of the wrapping film according to the invention and the use of the wrapping film in a halogen-free adhesive tape, further uses of the same and processes for producing the wrapping film.

The details given below in phr mean parts by weight of the component in question based on 100 parts by weight of all polymer components of the film. In the case of a wrapping film with a coating (for example with adhesive), only the parts by weight of all polymer components of the polyolefin-containing layer are taken into account.

Accordingly, the invention relates to a halogen-free calendered, in particular flame-retardant, wrapping film made of polyolefin, preferably polypropylene copolymer, the melt index of the polyolefin being below 5 g / 10 min, preferably below 1 g / 10 min and in particular below 0.7 g / 10 min.

The thickness of the film according to the invention is in the range from 30 to 180 μm, preferably 50 to 150 μm, in particular 55 to 100 μm. The surface can be textured or smooth. The surface is preferably set slightly matt. This can be achieved by using a filler with a sufficiently large particle size or by an embossing roller on the calender.

In a preferred embodiment, the film is provided on one or both sides with a pressure-sensitive adhesive layer in order to make the application simple, so that there is no need to fix the winding film at the end of the winding process.

The wrapping film according to the invention is essentially free of volatile plasticizers such as DOP or TOTM and therefore has excellent fire behavior and low emissions (plasticizer evaporation, fogging). A film according to the invention can be produced for the person skilled in the art, surprisingly and unpredictably. Surprisingly, the thermal aging resistance is not worse compared to PVC as a high-performance material, but rather comparable or even better.

The wrapping film according to the invention has a force in the longitudinal direction at 1% elongation of 0.6 to 5 N / cm, preferably from 1 to 4 N / cm, and at 100% elongation a force of 2 to 20 N / cm, preferably from 3 to 10 N / cm.

In particular, the force at 1% elongation is greater than or equal to 1 N / cm and the force at 100% elongation is less than or equal to 15 N / cm.

The 1% force is a measure of the rigidity of the film, and the 100% force is a measure of the suppleness when winding with strong deformation due to high winding tension. However, the 100% force must not be too low, because otherwise the tear strength is too low.

To achieve these force values, the wrapping film preferably contains at least one polyolefin, in particular a polypropylene, with a flexural modulus of less than 900 MPa, preferably 500 MPa or less and in particular 80 MPa or less. More preferably, the polyolefin is a polypropylene copolymer that is from a process in which a PP homopolymer or PP random copolymer is further reacted with ethylene and propylene.

The melt index of the polyolefin for calender processing is below 5 g / 10 min, preferably below 1 g / 10 min and in particular below 0.7 g / 10 min. In the case of filler-containing films (for example with flame retardants), the melt indices of the mixtures (compounds) are additionally below 5 g / 10 min, preferably below 1 g / 10 min and in particular below 0.7 g / 10 min.

The crystallite melting point of the polyolefin is between 120 ° C and 166 ° C, preferably below 148 ° C, particularly preferably below 145 ° C. Is very particularly preferably the crystallite melting point. The polyolefin can be a soft ethylene homopolymer or ethylene or propylene copolymer.

The crystalline region of the copolymer is preferably a polypropylene with a random structure, in particular with a content of 6 to 10 mol% of ethylene. Depending on the block length of the polypropylene and the comonomer content of the amorphous phase, a polypropylene random copolymer (for example with ethylene) has a crystallite melting point between 120 ° C. and 145 ° C. (this is the range for commercial products). A polypropylene homopolymer is between 163 ° C and 166 ° C depending on the molecular weight and tacticity. If the homopolymer has a low molecular weight and is modified with EP rubber (for example grafting, reactor blend), the lowering of the melting point leads to a crystallite melting point in the range from approximately 148 ° C. to 163 ° C. The preferred crystallite melting point for the polypropylene copolymer according to the invention is therefore below 145 ° C. and is best achieved with a comonomer-modified polypropylene with a random structure in the crystalline phase and copolymeric amorphous phase. The low melting point of less than 145 ° C. compared to polypropylene homopolymer surprisingly has the advantage of being easier to process. In the case of high-melting polypropylene polymers, the calender temperature must be adjusted to the melting point. If the melting point is low, the calender temperature can be reduced. Surprisingly, this turns out to be an advantage, since it is observed that the problem of the melt sticking to the calender rolls decreases considerably at a lower temperature.

Such copolymers have a relationship between the comonomer content both in the crystalline and in the amorphous phase, the flexural modulus and the 1% tension value of the winding film produced therefrom. A high comonomer content in the amorphous phase enables a particularly low 1% force value. Surprisingly, a comonomer content in the hard crystalline phase has a positive influence on the flexibility of the filled film.

No restrictions are imposed on the monomer (s) in the polyolefin, but α-olefins such as ethylene, propylene, butylene (1), isobutylene, 4-methyl-1-pentene, hexene or octene are preferably used. Copolymers with three or more comonomers are included in the sense of this invention. Propylene and ethylene are particularly preferred as monomers for the polypropylene copolymer. The polymer can continue be modified by grafting, but not with polar comonomers such as maleic anhydride, vinyl esters or acrylate monomers, since these polar-modified polypropylene have a strong tendency to stick to the calender rolls. In the case of acrylic acid modification, it also turned out that the viscosity of the polymer melt is not stable during the process if metal hydroxides are present as flame retardants, since apparently ionomer formation occurs. Polypropylene copolymers are not only understood to mean copolymers in the strict sense of polymer physics such as block copolymers, but also commercially available thermoplastic PP elastomers with a wide variety of structures or properties. Such materials can be produced, for example, from PP homopolymers or random copolymers as a precursor by further reaction with ethylene and propylene in the gas phase in the same reactor or in subsequent reactors. If random copolymer is used as the starting material, the monomer distribution of ethylene and propylene in the EP rubber phase that forms is more uniform, which leads to better mechanical properties. This is another reason why a polymer with a crystalline random copolymer phase is preferred for the wrapping film according to the invention.

Common methods can be used for the production, examples being the gas phase, Cataloy, Spheripol, Novolen, and the Hypol process, which are described in Ullmann's Encyclopedia of Industrial Chemistry, 6th edition, Wiley-VCH 2002 ,

Suitable blending components are, for example, soft ethylene copolymers such as LDPE, LLDPE, Metallocen-PE, EPM or EPDM with a density of 0.86 to 0.92 g / cm ^3, preferably 0.86 to 0.88 g / cm ³ . Soft hydrogenated random or block copolymers of ethylene or (optionally substituted) styrene and butadiene or isoprene are also suitable, the flexibility to bring the force at 1% elongation and in particular the shape of the force-elongation curve of the wrapping film into the optimal range. If, in addition to the polypropylene copolymer according to the invention, a further copolymer containing ethylene or propylene is used, it preferably has a specified melt index in the range of ± 50% of the melt index of the polypropylene copolymer. This does not take into account that the melt index of ethylene-containing copolymers is usually specified for 190 ° C and not for 230 ° C as is the case with polypropylene. The mixing components should also have very low melt indexes. The use of ethylene copolymers with monomers containing carbonyl groups such as ethylene acrylate (for example EMA, EBA, EEA, EAA) or ethylene vinyl acetate, as is known to the person skilled in the art, can improve the fire behavior of PP polymers. However, these are undesirable for the wrapping films according to the invention, since they lead to the film sticking to the calender from approximately 10 or 20 phr due to the polarity. This does not apply to particulate, cross-linked polar polymers such as acrylate impact modifiers or EVA dispersion powders with a polyvinyl alcohol shell.

Essentially only halogen-free materials are suitable as flame retardants, for example fillers such as polyphosphates, carbonates and hydroxides of aluminum or magnesium, borates, stannates and organic nitrogen-based flame retardants. The hydroxides are preferred, in various embodiments magnesium hydroxide having the advantage of security against overheating (leading to decomposition) and aluminum hydroxide having the cost advantage.

Red phosphorus can also be used, preferably it is not used (i.e. the amount is zero or not flame-retardant) because the processing is dangerous (self-ignition of released phosphine when mixed into the polymer, even with coated phosphorus, however much phosphine can be formed that there is a health risk for the operating personnel). In addition, when using red phosphorus, only colored and only black and brown products can be produced.

The flame retardant can be provided with a coating, which can also be applied subsequently during the compounding process. Suitable coatings are silanes such as vinylsilane or free fatty acids (or their derivatives) such as stearic acid, silicates, borates, aluminum compounds, phosphates, titanates but also chelating agents.

The content of free fatty acid or its derivative is preferably between 0.3 and 1% by weight.

Ground magnesium hydroxides are particularly preferred, examples being brucite

(Magnesium hydroxide), Kovdorskite (magnesium hydroxide phosphate), hydromagnesite

(Magnesium hydroxicarbon) and hydrotalcite (magnesium hydroxide with aluminum and carbonate in the crystal lattice), the use of brucite being particularly preferred. examples Mixtures of magnesium carbonates such as dolomite [CaCO ₃ ^• MgCO ₃ , M _r 184.41], magnesite (MgCO ₃ ), huntite [CaCO ₃ ^■ 3 MgCO ₃ , M _r 353.05] are permissible.

Magnesium hydroxide with an average particle size of more than 2 μm is particularly suitable, meaning the median value (d ₅₀ determined by laser light scattering according to Cilas) and in particular greater than or equal to 4 μm. The specific surface area (BET) is preferably less than 4 m ² / g (DIN 66131/66132). Usual wet-precipitated magnesium hydroxides are finely divided, as a rule the average particle size is 1 μm and below, the specific surface area is 5 m ² / g and more. The upper limit of the particle size distribution d ₉₇ is preferably not more than 20 μm in order to avoid the occurrence of holes in the film and embrittlement. Therefore, the magnesium hydroxide is preferably sieved. A content of particles with a diameter of 10 to 20 μm gives the film a pleasant looking matt effect.

The preferred particle shape is irregularly spherical, similar to that of river pebbles. It is preferably obtained by grinding. Magnesium hydroxide, which was prepared by dry grinding in the presence of a free fatty acid, in particular stearic acid, is particularly preferred. The fatty acid coating that forms improves the mechanical properties of mixtures of magnesium hydroxide and polyolefins and reduces the efflorescence of magnesium carbonate. The use of a fatty acid salt (for example sodium stearate) is also possible, but has the disadvantage that the wrapping film produced therefrom has an increased conductivity in moisture, which is disadvantageous in applications in which the wrapping film also takes on the function of an insulating tape. In the case of synthetically precipitated magnesium hydroxide, the fatty acid is always added in salt form because of its water solubility. This is another reason why a ground magnesium hydroxide is preferred over a precipitated one for the wrapping film according to the invention.

When using flame retardants, the amount is chosen so high that the wrapping film is flame-retardant, i.e. slowly burning. The fire speed according to FMVSS 302 for a horizontal sample is preferably below 200 mm / min, particularly preferably below 100 mm / min, in an outstanding embodiment of the wrapping film, it is self-extinguishing under these test conditions. The oxygen index (LOI) is preferably above 20%, in particular above 23% and particularly preferably above 27%. When using magnesium hydroxide (natural and synthetic), the proportion is preferably 70 to 200 phr and in particular 110 to 180 phr.

If there are no requirements for flame retardancy, preferably no flame retardant is used.

Other additives customary in films, such as fillers, pigments, anti-aging agents, nucleating agents, impact modifiers or lubricants, and others can be used to produce the wrapping film. These additives are described, for example, in the "Kunststoff Taschenbuch" by Hanser Verlag, ed. H. Saechtling, 28th edition or "Plastic Additives Handbook", Hanser-Verlag, ed. H. Doubt, 5th edition. In the following explanations, the respective CAS Reg.No. used.

A further prerequisite for sufficient short-term heat resistance and heat resistance is an adequate melting point of the polyolefin (at least 120 ° C.), a crosslinking or an adequate mechanical stability of the melt above the crystallite melting point. The latter can be achieved through the very low melt index according to the invention.

To achieve stable processability of the film and good aging stability of the wrapping tape, the use of the right anti-aging agent plays a special role. A primary and a secondary antioxidant should advantageously be used. The winding tapes according to the invention advantageously contain at least 4 phr of a primary antioxidant or preferably at least 0.3 phr, in particular at least 1 phr of a combination of primary and secondary antioxidants, the primary and secondary antioxidant function also being able to be combined in one molecule and optional in the quantities Stabilizers such as metal deactivators or light stabilizers are not included. In a preferred embodiment, the proportion of secondary antioxidant is more than 0.3 phr. Stabilizers for PVC products cannot be transferred to polyolefins. Secondary antioxidants break down peroxides and are therefore used in diene elastomers as part of anti-aging packages. Surprisingly, it was found that a combination of primary antioxidants (for example sterically hindered phenols or C radical scavengers such as CAS 181314-48-7) and secondary antioxidants (For example sulfur compounds, phosphites or sterically hindered amines), where the two functions can also be combined in one molecule, which also solves the problem with diene-free polyolefins such as polypropylene. Above all, the combination of a primary antioxidant, preferably sterically hindered phenols with a molecular weight of more than 500 g / mol (preferably> 700 g / mol), with a phosphitic secondary antioxidant (preferably with a molecular weight> 600 g / mol) is preferred. Phosphites or a combination of primary and several secondary anti-aging agents have so far not been used in wrapping films made of polyolefins such as polypropylene copolymers. The combination of a low-volatile primary phenolic antioxidant and a secondary antioxidant from the class of the sulfur compounds (preferably with a molecular weight of more than 400 g / mol, in particular> 500 g / mol) and from the class of the phosphites is suitable, wherein the phenolic, the sulfur-containing and the phosphitic functions need not be present in three different molecules, but more than one function can be combined in one molecule.

Examples:

• Phenolic function:

CAS 6683-19-8, 2082-79-3, 1709-70-2, 36443-68-2, 1709-70-2, 34137-09-2, 27676-62-6, 40601-76-1, 31851 -03-3, 991-84-4

• Sulfur-containing function: CAS 693-36-7, 123-28-4, 16545-54-3, 2500-88-1

• Phosphitic function:

CAS 31570-04-4, 26741-53-7, 80693-00-1, 140221-14-3, 119345-01-6, 3806-34-6, 80410-33-9, 14650-60-8, 161717 -32-4

• Phenolic and sulfur-containing function:

CAS 41484-35-9, 90-66-4, 110553-27-0, 96-96-5, 41484

• Phenolic and amine function: CAS 991-84-4, 633843-89-0 • Amine function: CAS 52829-07-9, 411556-26-7, 129757-67-1, 71878-19-8, 65447-77-0

The combination of CAS 6683-19-8 (for example Irganox 1010) with thiopropionic acid ester CAS 693-36-7 (Irganox PS 802) or 123-28-4 (Irganox PS 800) with CAS 31570-04-4 (Irgafos 168) is particularly preferred. A combination is preferred in which the proportion of secondary antioxidant exceeds that of the primary. In addition, metal deactivators for complexing heavy metal traces, which can catalytically accelerate aging, can be added. Examples are CAS 32687-78- 8, 70331-94-1, 6629-10-3, ethylenediaminetetraacetic acid, N, N'-di-salicylidene-1,2-diamino-propane or commercial products such as 3- (N-salicylol) - amino-1,2,4-triazole (Palmarole ADK STAB CDA-1), N, N'-bis [3- (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionyl] hydrazide (Palma - role MDA.P.10) or 2,2 "-oxamido-bis- [ethyl-3- (tert-butyl-4-hydroxyphenyl) propionate] (Palmarole MDA.P.11).

The selection of the anti-aging agents mentioned is of particular importance for the wrapping film according to the invention, since phenolic antioxidants alone or even in combination with sulfur-containing costabilizers generally do not make it possible to achieve practical products. In calender processing, in which a relatively long period of ingress of atmospheric oxygen is unavoidable, the use of phosphite stabilizers proves to be practically indispensable for sufficient thermal aging stability of the product. An amount of at least 0.1, preferably at least 0.3 phr is preferred for the phosphite stabilizer. In particular when using natural magnesium hydroxides such as brucite, migratable metal contaminants such as iron, manganese, chromium or copper can cause aging problems which can only be avoided by the above-mentioned knowledge of the correct combination and amount of anti-aging agents. As stated above, ground brucite has a number of technical advantages over precipitated magnesium hydroxide, so that the combination with antioxidants as described is particularly useful. For applications with high temperature loads (for example as a cable wrapping film in the engine compartment of motor vehicles or as an insulating winding of magnetic coils in television or PC screens), an embodiment is preferred which, in addition to the antioxidants, additionally contains a metal deactivator. The wrapping film according to the invention is preferably pigmented, in particular black. The coloring can be done in the base film, in the adhesive or another layer. The use of organic pigments or dyes in the wrapping film is possible; the use of carbon black is preferred. The proportion of carbon black is preferably at least 5 phr, in particular at least 10 phr, since it surprisingly shows a significant influence on the fire behavior. All types such as, for example, gas black, acetylene black, thermal black, fuma black and flame black can be used, carbon black being preferred, even if fuma black is customary for coloring films. For optimum aging, carbon black types with a pH in the range from 6 to 8 are preferred, in particular flame black.

The wrapping film is produced on a calender. This process is described, for example, in Ullmann's Encyclopedia of Industrial Chemistry, 6th edition, Wiley-VCH 2002. The compound from the main components or all components can be produced in a compounder such as a kneader (for example a stamp kneader) or an extruder (for example a twin-screw extruder, planetary roller extruder) and then converted into a solid form (for example granules), which is then in an extruder, a kneader or the rolling mill of a calender system is melted and further processed. High amounts of filler result in slight inhomogeneities (defects) which greatly reduce the breakdown voltage. The mixing process must therefore be carried out so thoroughly that the film made from the compound reaches a breakdown voltage of at least 3 kV / 100 μm, preferably at least 5 kV / 100 μm. The compound and film are preferably produced in one operation. The melt is fed from the compounder directly to the calender, the melt possibly passing through auxiliary devices such as filters, metal detectors or rolling mills. The film is oriented as little as possible in the manufacturing process in order to achieve good hand tearability, low force value at 1% elongation and low shrinkage.

The shrinkage of the wrapping film in the longitudinal direction after heat storage (30 minutes in an oven at 125 ° C. on a talc layer) is less than 5%, preferably less than 3%. The mechanical properties of the wrapping film according to the invention are preferably in the following areas:

Elongation at break in md (machine direction) from 300 to 1000, particularly preferably from 500 to 800%,

• tensile strength in md in the range from 4 to 15, particularly preferably from 5 to 8 N / cm, the film being cut with sharp blades to determine the data.

In the preferred embodiment, the wrapping film is provided on one or both sides, preferably on one side, with a sealing or pressure-sensitive adhesive coating in order to avoid the need to fix the winding end by means of an adhesive tape, wire or knotting. The amount of the adhesive layer is in each case 10 to 40 g / m ^2, preferably 18 to 28 g / m ² (this is the amount after a possible removal of water or solvent; the numerical values also correspond approximately to the thickness in μm). In a case with an adhesive coating, the information given here on the thickness and the thickness-dependent mechanical properties relate exclusively to the polypropylene-containing layer of the wrapping film without taking into account the adhesive layer or other layers which are advantageous in connection with adhesive layers. The coating does not have to be over the entire surface, but can also be carried out over part of the surface. An example is a wrapping film, each with a pressure-sensitive adhesive strip on the side edges. This can be cut off to form approximately rectangular sheets, which are glued to the cable bundle with one adhesive strip and then wound until the other adhesive strip can be glued to the back of the wrapping film. Such a hose-like wrapping, similar to a sleeve packaging, has the advantage that the flexibility of the wiring harness is practically not impaired by the wrapping.

All common types can be used as adhesives, especially those based on rubber. Such rubbers can be, for example, homo- or copolymers of isobutylene, 1-butene, vinyl acetate, ethylene, acrylic esters, butadiene or isoprene. Formulations based on polymers based on acrylic acid esters, vinyl acetate or isoprene are particularly suitable.

To optimize the properties, the self-adhesive used can be used with one or more additives such as tackifiers (resins), plasticizers, fillers. Substances, flame retardants, pigments, UV absorbers, light stabilizers, anti-aging agents, photoinitiators, crosslinking agents or crosslinking promoters can be mixed. Tackifiers are, for example, hydrocarbon resins (for example polymers based on unsaturated C ₅ or C ₉ monomers), terpene phenol resins, polyterpene resins from raw materials such as α- or β-pinene, aromatic resins such as coumarone-indene resins or resins based on styrene or α-methylstyrene, such as rosin and its secondary products, for example disproportionated, dimerized or esterified resins, for example reaction products with glycol, glycerol or pentaerythritol, to name just a few, and further resins (as listed, for example, in Ulimann's encyclopedia of industrial chemistry , Volume 12, pages 525 to 555 (4th edition), Weinheim). Resins without easily oxidizable double bonds such as terpene phenol resins, aromatic resins and particularly preferably resins which are produced by hydrogenation, such as, for example, hydrogenated aromatic resins, hydrogenated polycyclopentadiene resins, hydrogenated rosin derivatives or hydrogenated terpene resins, are preferred.

Suitable fillers and pigments are, for example, titanium dioxide, calcium carbonate, zinc carbonate, zinc oxide, silicates or silica. Suitable admixable 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 low molecular weight nitrile or polyisoprene rubbers), liquid polymers of butene and / or isobutene, acrylic acid esters, polyvinyl Liquid and soft resins based on the raw materials of adhesive resins, wool wax and other waxes or liquid silicones. Crosslinking agents are, for example, isocyanates, 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. Anti-aging agents are, for example, sterically hindered phenols, which are known, for example, under the trade name Irganox ™.

Networking is advantageous because the shear strength (expressed, for example, as holding power) is increased and thus the tendency to deform the rolls during storage (telescoping or formation of cavities, also called gaps) is reduced. The squeezing out of the adhesive mass is also reduced. This is expressed in the non-sticky side edges of the rolls and non-sticky edges in the wrapping film which is spirally guided around the cable. The holding power is preferably above 150 minutes. The adhesive strength on steel should be in the range of 1.5 to 3 N / cm.

In summary, the preferred embodiment has a solvent-free self-adhesive composition on one side, which has been brought about by melt or dispersion coating. Dispersion adhesives are particularly preferably those based on polyacrylate.

It is advantageous to use a primer layer between the wrapping film and the adhesive to improve the adhesion of the adhesive to the wrapping film and thus to avoid the transfer of adhesive to the back of the film while the rolls are being unwound.

The known dispersion and solvent systems can be used as primers, for example based on rubber containing isoprene or butadiene and / or cyclo-rubber. Isocyanates or epoxy resins as additives improve the adhesion and in some cases also increase the shear strength of the pressure-sensitive adhesive. Physical surface treatments such as flame treatment, corona or plasma or coextrusion layers are also suitable for improving the adhesion. The use of such methods on solvent-free adhesive layers, in particular those based on acrylate, is particularly preferred.

The rear side can be coated using known release agents (optionally mixed with other polymers). Examples are stearyl compounds (for example polyvinylstearyl carbamate, stearyl compounds of transition metals such as Cr or Zr, ureas from polyethyleneimine and stearyl isocyanate, polysiloxanes (for example as a copolymer with polyurethanes or as a graft copolymer on polyolefin), thermoplastic see fluoropolymers. The term stearyl is synonymous for all straight or branched alkyls or alkenyls with a carbon number of at least 10, such as octadecyl.

Descriptions of the usual adhesives, as well as back coatings and primers can be found, for example, in the "Handbook of Pressure Sensitive Adhesive Technology", D. Satas, (3rd edition). In one embodiment, the backside primer and adhesive coatings mentioned are possible by coextrusion.

The design of the back of the film can also serve to increase the adhesion of the adhesive on the back of the film (for example to control the unwinding force). In the case of polar adhesives, such as those based on acrylate polymers, the back adhesion on a film based on polypropylene polymers is often not sufficient. To increase the rolling force, an embodiment is claimed in which polar rear surfaces are achieved by corona treatment, flame pretreatment or coating / coextrusion with polar raw materials. As an alternative, a wrapping film is claimed in which the logs have been tempered (stored in the heat) before cutting. Both methods can also be used in combination. The wrapping film according to the invention preferably has a rolling force of 1.2 to 6.0 N / cm, very particularly preferably 1.6 to 4.0 N / cm and in particular 1.8 to 2.5 N / cm at 300 mm / min Unwind speed. Tempering is known for PVC winding tapes, but for a different reason. In contrast to partially crystalline polypropylene copolymer films, soft PVC films have a wide softening range, and since the adhesive is little shear-resistant due to the emigrated plasticizer, PVC wrapping tapes tend to telescope. This disadvantageous roll deformation, in which the core is pressed out of the rolls laterally, can be prevented if the material is stored for a longer period of time before being cut or if it is subjected to heat treatment for a short time (temporary storage in the heat). However, the method according to the invention involves tempering to increase the unwinding force of material with a non-polar polypropylene back and polar adhesive, such as polyacrylate or EVA, since these adhesives have an extremely low back adhesion on polypropylene compared to PVC. An increase in the unwinding force due to tempering or physical surface treatment is not necessary in the case of soft PVC winding tapes, since the adhesive that is usually used has a sufficiently high adhesion to the polar PVC surface. In the case of polyolefin wrapping films, the importance of back adhesion is particularly pronounced, since, due to the higher force at 1% elongation (due to the flame retardant and the lack of conventional plasticizers), a significantly higher back adhesion or unwinding force is required compared to PVC film in order to achieve sufficient stretch to be provided for the application when unrolling. The preferred embodiment of the wrapping film is therefore produced by tempering or physical surface treatment in order to to achieve outstanding rolling force and elongation during unwinding, the rolling force at 300 mm / min preferably being at least 50% higher than without such a measure.

In the case of an adhesive coating, the wrapping film is preferably stored beforehand at least 3 days, particularly preferably at least 7 days before the coating in order to achieve recrystallization so that the rolls do not have any tendency to telescope (probably because the film shrinks during crystallization). , The film is preferably guided on the coating system over heated rollers for leveling (improving flatness), which is not common for PVC wrapping films.

Films made of polyethylene and polypropylene cannot usually be torn or torn off by hand. As semi-crystalline materials, they can be stretched easily and therefore have a high elongation at break, which is usually well above 500%. When trying to tear such films, an elongation occurs instead of a tear. Even high forces cannot necessarily overcome the typically high breaking forces. Even if this succeeds, a good-looking and glue-off tear is not produced, since a thin, narrow tail is formed at both ends. Additives cannot solve this problem, even if fillers reduce the elongation at break in large quantities. If polyolefin films are stretched biaxially, the elongation at break is reduced by more than 50%, which promotes tearability. However, the attempt to transfer this method to soft wrapping foils failed because the 1% force value increases significantly and the force-elongation curve becomes significantly steeper. The consequence of this is that the flexibility and conformability of the wrapping film deteriorate drastically. It also turns out that films with such a high filler content are hardly stretchable from a production point of view due to the high number of tears.

Surprisingly, a solution has been found through the cutting process when assembling the rolls. When the wrapping film rolls are produced, rough cut edges are produced which, when viewed microscopically, form cracks in the film, which then obviously promote tear. This is possible in particular by using a squeeze cut with blunt or defined serrated rotating knives on bale goods (jumbos, rolls of great length) or by a cut-off cut with fixed blades or rotating knives of stick goods (rolls of production width and sales length). The elongation at break can be The cut of the blades and knives can be adjusted. It is preferred to carry out the production of logs with a cut-off cut with blunt fixed blades. By strongly cooling the bars before cutting, the cracking during the cutting process can be improved even further. In the preferred embodiment, the elongation at break of the specially cut wrapping film is at least 30% lower than when cutting with sharp blades. In the particularly preferred foils cut with sharp blades, the elongation at break is 500 to 800%, in the embodiment of the foil whose side edges are damaged in a defined manner during cutting, between 200 and 500%.

The logs can be subjected to heat storage beforehand to increase the unwinding force. The cutting of conventional winding tapes with tissue, fleece and foil backing (for example PVC) is done by scissors cut (between two rotating knives), parting cut (fixed or rotating knives are pressed into a rotating rod of the product), blade cutting (the web is divided by sharp blades as it passes) or crush cut (between a rotating knife and a roller).

The aim of cutting is to produce rolls that are ready for sale from jumbos or bars, but not to produce rough cut edges for easier hand tearing. In the case of PVC wrapping foils, the parting cut is quite common, since the process is economical with soft foils. However, the material can be torn by hand because PVC is amorphous in contrast to polypropylene and therefore does not stretch when torn, but is only stretched a little. To ensure that the PVC films do not tear too easily, care must be taken to ensure sufficient gelling during film production, which is an obstacle to optimal production speed.Therefore, material with a higher molecular weight is often used instead of standard PVC with a K value of 63 to 65 Corresponds to K values of 70 and more. The cut-off cut has a different reason for the wrapping films according to the invention made of polypropylene than for those made of PVC.

The wrapping film according to the invention is excellently suitable for wrapping elongated material such as ventilation pipes, field coils or cable sets in vehicles. The wrapping film according to the invention is also suitable for other applications, for example for ventilation pipes in air conditioning, since the high flexibility ensures good conformability to rivets, beads and folds. Today's occupational hygiene and ecological requirements are taken into account by not using halogen-containing raw materials, this also applies to volatile plasticizers, unless the quantities are so small that the fogging value is over 90%. The freedom from halogen is extremely important for the thermal recycling of waste containing such winding tapes (for example, waste incineration of the plastic fraction from vehicle recycling). The product according to the invention is halogen-free in the sense that the halogen content of the raw materials is so low that it plays no role in the flame resistance. Halogens in trace amounts, such as those that could occur due to impurities, process additives (fluoroelastomer) or as residues of catalysts (for example from the polymerisation of polymers) are not taken into account. The absence of halogens entails the property of easy flammability, which does not meet the safety requirements in electrical applications such as household appliances or vehicles. The problem of lack of flexibility when using conventional PVC substitute materials such as polypropylene, polyethylene, polyester, polystyrene, polyamide or polyimide for the wrapping film is not solved in the underlying invention by volatile plasticizers, but rather by the use of a polyolefin, preferably a mixture of a PP Copolymer with a low flexural modulus polyolefin or use of a PP polymer with a low flexural modulus.

Test Methods

The measurements are carried out in a test climate of 23 ± 1 ° C and 50 ± 5% rel. Humidity carried out.

The density of the polymers is determined according to ISO 1183 and the flexural modulus according to ISO 178 and expressed in g / cm ³ or MPa. (The bending module according to ASTM D790 is based on different dimensions of the test specimens, but the result is The melt index is checked according to ISO 1133 and expressed in g / 10 min. As usual in the market, the test conditions are 230 ° C and 2.16 kg for polymers with crystalline polypropylene and 190 ° C and 2.16 kg for polymers with crystalline polyethylene. The crystallite melting point (Tcr) is determined with DSC according to MTM 15902 (Basell method) or ISO 3146.

The average particle size of the filler is determined by laser light scattering according to Cilas; the median value d ₅₀ is decisive.

The specific surface area (BET) of the filler is determined according to DIN 66131/66132.

The tensile elongation behavior of the wrapping film is determined on test specimens of type 2 (rectangular 150 mm long and if possible 15 mm wide test strips) according to DIN EN ISO 527-3 / 2/300 with a test speed of 300 mm / min, a clamping length of 100 mm and a preload of 0.3 N / cm determined. In the case of samples with rough cut edges, the edges must be trimmed with a sharp blade before the tensile test. To determine the force or tension at 1% elongation, a test speed of 10 mm / min and a preload setting of 0.5 N / cm are used to measure on a tensile testing machine model Z 010 (manufacturer Zwick). The testing machine is specified because the 1% value can be influenced somewhat by the evaluation program. Unless otherwise stated, the tensile elongation behavior is checked in the machine direction (MD, running direction). The force is expressed in N / strip width and the tension in N / strip cross-section, the elongation at break in%. The test results, in particular the elongation at break (elongation at break), must be statistically verified by a sufficient number of measurements.

The adhesive forces are determined at a peel angle of 180 ° according to AFERA 4001 on (if possible) 15 mm wide test strips. Here, steel plates according to the AFERA standard are used as the test surface, unless another primer is mentioned.

The thickness of the wrapping film is determined according to DIN 53370. A possible layer of pressure sensitive adhesive is subtracted from the measured total thickness. The holding power is determined according to PSTC 107 (10/2001), whereby the weight is 20 N and the dimensions of the bonding surface are 20 mm in height and 13 mm in width.

The rolling force is measured at 300 mm / min according to DIN EN 1944.

The hand tearability cannot be expressed in numbers, even if breaking strength, elongation at break and impact strength (all measured lengthways) are of major influence.

Rating:

, +++ = very light,

- ++ = good,

- + = still processable, - = difficult to process,

- - = can only be torn off with great effort, the ends are dirty,

- --- = cannot be processed

The fire behavior is measured according to MVSS 302 with a horizontal sample. In the case of a one-sided pressure-sensitive adhesive coating, this is on top. Another method is to check the Oxygen Index (LOI). For this, testing is carried out under the conditions of JIS K 7201.

The heat stability is determined based on ISO / DI N 6722. The furnace is operated according to ASTM D 2436-1985 with 175 air changes per hour. The test time is 3000 hours. The test temperatures selected are 85 ° C (class A), 105 ° C (similar to class B but not 100 ° C) and 125 ° C (class C). The rapid aging takes place at 136 ° C, the test is passed if the elongation at break is still at least 100% after 20 days of aging.

During the compatibility test, the heat is stored on standard conductors

(Cables) with polyolefin insulation (polypropylene or radiation cross-linked polyethylene) for

Motor vehicles performed. For this test specimens are made of 5 conductors with a cross-section of 3 to 6 mm ² and a length of 350 mm with wrapping foil by wrapping with 50% pung manufactured. After the test specimens had been aged for 3,000 hours in a forced-air oven (conditions as in the heat stability test), the samples are conditioned at 23 ° C and wrapped by hand around a mandrel according to ISO / DIN 6722, the winding dome has a diameter of 5 mm, the weight has a mass of 5 kg and the winding speed is 1 revolution per second. The samples are then examined visually for defects in the wrapping film and in the wire insulation under the wrapping film. The test is unsuccessful if there are cracks in the wire insulation, in particular if this can be seen on the mandrel before bending. If the wrapping film shows cracks or has melted in the oven, the test is also considered failed. In the 125 ° C test, samples were sometimes also checked at other times. The test time is 3000 hours unless expressly stated otherwise in the individual case.

The short-term heat resistance is measured on cable bundles made of 19 type TW wires with a cross section of 0.5 mm ² , which are described in ISO 6722. For this purpose, the wrapping film is wound with 50% overlap on the cable bundle, the cable bundle is bent around a mandrel with a diameter of 80 mm and stored in a convection oven at 140 ° C. After 168 hours, the sample is removed from the oven and checked for damage (cracks).

To determine the heat resistance, the wrapping film is 30 min. stored at 170 ° C, 30 min. cooled to room temperature and wound with at least 3 turns with a 50% overlap around a mandrel of 10 mm diameter. The pattern is then checked for damage (cracks).

In the cold test, the test specimen described above is cooled to -40 ° C based on ISO / DIS 67224 hours and the specimen is wound by hand on a mandrel with a diameter of 5 mm. The samples are visually checked for defects (tears) in the adhesive tape.

The breakdown voltage is measured according to ASTM D 1000. The number taken is the highest value that the pattern can withstand for one minute at this tension. This number is converted to a sample thickness of 100 μm.

Example: A sample with a thickness of 200 μm withstands a maximum voltage of 6 kV after one minute, the calculated breakdown voltage is 3 kV / 100 μm.

The fogging value is determined in accordance with DIN 75201 A.

Claims

claims

1. Halogen-free calendered, in particular flame-retardant wrapping film made of polyolefin, characterized in that the melt index of the polyolefin is below 5 g / 10 min, preferably below 1 g / 10 min and in particular below 0.7 g / 0 min.

2. Wrapping film according to claim 1, characterized in that the mixture (compound) of the film has a melt index below 5 g / 10 min, preferably below 1 g / 10 min and in particular below 0.7 g / 10 min.

3. Wrapping film according to claim 1 or 2, characterized in that the proportion of flame retardant is at least 100 phr.

4. Wrapping film according to at least one of the preceding claims, characterized in that the thickness of the wrapping film is 30 to 180 μm, in particular 50 to 150 μm, very particularly 55 to 100 μm, the force in the running direction at 1% elongation is a value from 0.6 to 5 N / cm, particularly 1 to 3 N / cm, the force at 100% elongation has a value of 2 to 20 N / cm, particularly 3 to 10 N / cm and / or the crystallite melting point Polypropylene copolymer is less than 166 ° C.

5. Wrapping film according to at least one of the preceding claims, characterized in that the polyolefin is a polypropylene copolymer.

6. Wrapping film according to at least one of the preceding claims, characterized in that in addition to the preferred polypropylene polymer, ethylene-propylene copolymers from the classes of the EPM and EPDM are present in the wrapping film.

7. Wrapping film according to at least one of the preceding claims, characterized in that the wrapping film has at least one polypropylene with a flexural modulus of less than 900 MPa, preferably of 500 or less and particularly preferably of 80 MPa or less, and / or contains a crystallite melting point between 120 ° C and 166 ° C, preferably below 148 ° C, particularly preferably below 145 ° C

8. wrapping film according to at least one of the preceding claims, characterized in that the wrapping film on one or both sides, in particular on one side, an adhesive layer, which is preferably based on polyisoprene, ethylene vinyl acetate copolymer and / or polyacrylate, and optionally a primer layer between the film and adhesive layer, the amount of the adhesive layer in each case being 10 to 40 g / m ² , preferably 18 to 28 g / m ² , the adhesive force on steel 1.5 to 3 N / cm, the unrolling force 1.2 to 6.0 N / cm at a rolling speed of 300 mm / min, preferably 1.6 to 4.0 N / cm, particularly preferably 1.8 to 2.5 N / cm, and / or the holding power is more than 150 min.

9. Wrapping film according to at least one of the preceding claims, characterized in that the wrapping film has a solvent-free PSA which is produced by coextrusion, melt coating or dispersion coating, preferably a dispersion PSA and in particular one based on polyacrylate, this adhesive using a flame or corona pretreatment or an adhesion promoter layer, which is applied by coextrusion or coating, is connected to the surface of the carrier film.

10. Wrapping film according to at least one of the preceding claims, characterized in that the oxygen index (LOI) is above 20, preferably above 23 and particularly preferably above 27%.

11. Wrapping film according to at least one of the preceding claims, characterized in that the fire speed according to FMVSS 302 for a horizontal sample is below 200 mm / min, preferably below 100 mm / min, and in particular the sample is self-extinguishing under these test conditions.

12. Wrapping film according to one of the preceding claims, characterized in that the proportion of carbon black is at least 5 phr, preferably at least 10 phr, the carbon black preferably having a pH of 6 to 8.

3. Use of a wrapping film according to at least one of the preceding claims for bundling, protecting, labeling, isolating or sealing ventilation pipes or wires or cables and for sheathing cable sets in vehicles or field coils for picture tubes.