EP1678247A1

EP1678247A1 - Halogen-free soft wrapping foil made of a polyolefin containing magnesium hydroxide

Info

Publication number: EP1678247A1
Application number: EP04766812A
Authority: EP
Inventors: Bernhard MÜSSIG; Ingo Neubert
Original assignee: Tesa SE
Current assignee: Tesa SE
Priority date: 2003-10-14
Filing date: 2004-09-16
Publication date: 2006-07-12
Also published as: US20070275236A1; MXPA06004111A; WO2005037906A1; JP2007513211A; DE10348473A1

Abstract

Disclosed is a halogen-free wrapping foil which is made of a polyolefin and magnesium hydroxide and is characterized in that the magnesium hydroxide is provided with an optionally irregular spherical shape while the wrapping foil has a thickness of 30 to 200 µm, especially 50 to 130 µm.

Description

HALOGEN-FREE SOFT WRAPPING FILM MADE FROM A POLYOLEFIN CONTAINING MAGNESIUM HYDROXIDE

The present invention relates to a filled, soft, halogen-free, flame-retardant wrapping film made of polyolefin and magnesium hydroxide with an (irregular) spherical structure and a particle size of several μm for wrapping, for example, ventilation ducts in air conditioning systems or wires or cables, and in particular for wiring harnesses in vehicles or field coils for picture tubes, which is preferably equipped with a pressure-sensitive adhesive coating. 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, which are usually equipped with a one-sided adhesive coating. There is an increasing desire to eliminate disadvantages of these products. Corresponding disadvantages include evaporation of plasticizer and high halogen content.

In addition, PVC is reaching the limits of today's requirements for thermal stability. PVC wrapping films are now commercially produced exclusively by calendering on a commercial scale. In the case of new materials according to the invention, extrusion can also be used, as a result of which the production process would be more cost-effective, layer thicknesses reduced and the film would be more versatile due to the multilayer structure (coextrusion). In addition to the wrapping foils, there are other wrapping tapes made of textile materials, for example. When trying to replace PVC, brominated connections are usually used, which do not meet the further requirements of complete freedom from halogen. Phosphates are particularly effective in combination with nitrogen compounds, these unfortunately have a number of disadvantages. Commercially available precipitated magnesium and aluminum hydroxides are also known as flame retardants for plastics. They are used with some success in halogen-free cable insulation. The flame resistance is significantly worse in relation to the amount used than with the flame retardants mentioned above. Aluminum hydroxide is considerably cheaper than magnesium hydroxide, but has its limits due to its tendency to split off water at the processing temperature. The transfer of this experience into the commercial use of such hydroxides on winding and insulating tapes has so far not been successful.

The main reasons for this are:

• The lack of copper wire for cooling and the thinner layer thickness (approx. 60 to 100 μm instead of 200 to 500 μm) requires considerably higher amounts of filler in order to achieve the same flame resistance. • The lack of mechanical support due to the copper wire and the thinner layer thickness requires significantly higher specific tensile strength, which means a small amount of filler and requires specially selected fillers and polyolefins.

• The thinner layer thickness places higher demands on the flow behavior in thermoplastic processing.

• The production width of approx. 1500 mm compared to a few mm wire circumference of the insulation places higher demands on the flow behavior for thermoplastic processing in order to achieve sufficient uniformity across the width. • In order to achieve sufficient thermal resistance in the sense of melting, polypropylene should be contained in the polymer mixture, which excludes the use of aluminum hydroxide.

• In order to achieve sufficient thermal resistance in the sense of melts, the melt index should be as low as possible in order to achieve an internal strength of the melt when the melting point is exceeded, which contradicts the film extrusion process customary for polyolefins.

The prior art has so far not found the magnesium hydroxide which is optimal for processing, especially not in the case of trying significantly higher amounts than before in order to achieve excellent flame retardancy. So far are not the right polyolefins have been found to meet the requirements for the processing of highly filled polymer melts and to achieve the necessary mechanical properties of the film. The aging stability has also not been brought up to a high level because none, too little or the wrong aging protection agents have been tried for this application.

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 questionable. 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. Therefore, the wall thickness of the cable insulation and the thickness of the PVC film used 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 winding tapes 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.

DE 200 22 272 U1, EP 1 123 958 A1 and WO 99/61541 A1 describe winding 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.

In modern vehicle construction, the wiring harnesses are becoming thicker and stiffer due to the large number of electrical consumers and the increased information transfer within the vehicles, while the installation space is being reduced more and more, making assembly (when installing in the body) more problematic. This makes thin film tape advantageous. Furthermore, the cable winding tapes are expected to be easy and quick to process for efficient and inexpensive cable harness production. Wrapping tapes based on soft PVC films are used in automobiles for bandaging electrical cables to cable harnesses. In the early days of technical development, the focus was on improving the electrical insulation when using these winding tapes, which had originally been developed as insulating tapes, such cable harness tapes must now perform other functions such as bundling and permanently fixing a large number of individual cables into a stable cable harness, and protecting the cable harness Single cable and the entire cable harness against mechanical, thermal and chemical damage.

DE 199 10 730 A1 describes a laminate carrier which consists of velor or foam and a fleece which is adhesively bonded by means of a double-sided adhesive tape or with a hot melt adhesive.

EP 0 886 357 A2 describes a three-layer protective covering made of a spunbonded nonwoven fabric, a PET knitted fabric and a foam or felt strip which are laminated together, the protective covering additionally being provided at least partially with adhesive strips and Velcro fastening systems.

EP 1 000 992 A1 describes a perforated cotton fleece with a 10 to 45 μm thick polyethylene coating and an additional release coating.

DE-G 94 01 037 describes an adhesive tape with a band-shaped, textile carrier, which consists of a sewing fleece, which in turn is formed from a plurality of sewn seams running parallel to one another. The fleece proposed here should have a thickness of 150 to 400 μm with a basis weight of 50 to 200 g / m ² .

DE 44 42 092 C1 describes an adhesive tape based on sewing fleece, which is coated on the back of the carrier. DE 44 42 093 C1 is based on the use of a nonwoven as a carrier for an adhesive tape which is produced by the formation of stitches from the fibers of the nonwoven reinforced cross-fiber nonwoven, ie a nonwoven known to the person skilled in the art under the name Malivlies. DE 44 42 507 C1 discloses an adhesive tape for cable bandaging, but it is based on so-called Kunit or multi-knit nonwovens. Nonwovens are used in all three documents, which have a basis weight of approximately 100 g / m ² , as can be seen from the examples. DE 195 23 494 C1 discloses the use of an adhesive tape with a carrier made of nonwoven material with a thickness of 400 to 600 μm for bandaging cable harnesses, which is coated on one side with an adhesive.

DE 199 23 399 A1 discloses an adhesive tape with a tape-shaped carrier made of nonwoven material, which is coated on at least one side with an adhesive, the nonwoven having a thickness of 100 μm to 3000 μm, in particular 500 to 1000 μm.

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 considerable shortcomings with regard to their flexibility, processability, aging resistance or compatibility with the cable materials. However, the most serious disadvantage of polyester is its 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. These do not contain magnesium hydroxide with (irregular) spherical structure and or with Particle size of several μm. 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 usually melt when trying to test for heat aging resistance), and when using polypropylene polymers, the material is too inflexible.

There has been no shortage of attempts to use fillers as halogen-free flame retardants. The fire behavior can be improved considerably by using larger amounts of conventional flame-retardant, fine-particle and platelet-shaped metal hydroxide fillers (for example based on magnesium, calcium or aluminum). Unfortunately, however, these mixtures are difficult to process into films, and the products made from them are very stiff and do not even come close to the flame resistance of PVC or halogen-free PVC-free wrapping films because they cannot be used in sufficient quantities. With filler quantities of 3 to 30 parts by weight based on 100 parts by weight of polyolefin, as can be implemented in other film applications such as deep-drawn films for rigid cups, however, no significant flame retardancy can be achieved. Phosphates such as ammonium or ethylenediamine polyphosphate have a somewhat higher flame retardant performance in polyolefins than the metal hydroxides described, in particular in a synergistic combination with nitrogen-containing flame retardants. Unfortunately, they are characterized by sensitivity to hydrolysis, which manifests itself, for example, in roller deposits during thermoplastic processing and, after aging, in insufficient electrical and mechanical properties. Insofar as relevant patents refer to magnesium hydroxide, they are platelet-shaped fine-particle (precipitated synthetic) types which have the disadvantages listed below compared to (irregularly) spherical, for example ground natural types. Furthermore, the inventions mentioned do not contain any combinations of magnesium hydroxide and heat-resistant polypropylenes, as are preferred according to the invention.

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. 48 to 90 phr of aluminum hydroxide with a BET value of 4 and 7 are used as flame retardants (corresponding to an estimated d ₅₀ particle size of 1 to 2 μm). The size and shape of the aluminum hydroxide complicates incorporation into the polyolefin, which is evident from the relatively low content thereof, whereas in the preferred embodiment of the invention the content of hydroxide (magnesium hydroxide) is above 100 phr in order to achieve high flame resistance. A significant disadvantage of the backing film is also the low softening temperature due to the ethylene / vinyl acetate or ethylene / acrylate copolymer, which is, however, necessary to achieve acceptable flame resistance due to the small amount of filler. However, the low decomposition temperature of aluminum hydroxide does not allow the use of the more heat-resistant but higher melting polypropylene. To counteract the softening problem, the use of silane crosslinking is described. This networking method is complex and in practice only leads to very unevenly networked material, so that no stable production process or uniform quality of the product can be realized in production.

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 A. 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, the film becomes particularly brittle as it ages. The use on conventional cables with insulation made of polyolefin and aluminum or magnesium hydroxide leads to poor compatibility because the hydroxides easily split water, from which the phosphate hydrolyzes to phosphoric acid (decomposition catalyst). In addition, the fire behavior of such wiring harnesses is poor, since these metal hydroxides with phosphates have an antagonistic effect as explained below. The insulating tapes described are too thick and too stiff for wiring harness tapes.

Attempts to solve the dilemma of too low a softening temperature, flexibility, flame resistance and freedom from halogen are described in the following publications. 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 synthetic platelet-shaped, finely divided, precipitated magnesium hydroxide with a special surface in combination with red phosphorus is described as a flame retardant. The d ₅₀ value is between 0.61 and 1.4 μm. The particle shape and size make it difficult to incorporate, so despite the use of Tuftec (Asahi) as a compatibilizer, only 63 phr of magnesium hydroxide can be incorporated, which necessitates the use of 11 phr of red phosphorus in order to achieve acceptable flame retardancy. As with phosphine, the use of red phosphorus causes processing and prevents the production of white or colored foils. As with the aforementioned document, the problem of softening at a relatively low temperature cannot be solved.

A very similar combination of polyolefin and EVA is described in EP 1 097 976 A1. Here a PP polymer is used instead of LLDPE. The main idea of this patent is the achievement of certain mechanical properties at 100 ° C by the PP polymer, which means in concrete terms that the problem of insufficient heat resistance of mixtures of polyethylene homopolymer and ethylene copolymer is to be solved. This results in little flexibility. This disadvantage of the invention can also be confirmed by measurements on the reworked examples. The third component of the mixture (in addition to PP polymer and flame retardant) is EVA or EEA, which serves to improve the flexibility and flame retardancy of the combinations of polyethylene or polypropylene and filler, which can be seen from the LOI values of the examples. Due to their composition, these foils are hard and inflexible. A review of the force in the running direction at 1% elongation reveals values of over 10 N / cm when the examples are reworked. In practice, products with a value of around 1 N / cm have prevailed in the PVC wrapping films currently in use. This underlines that these foils are too inflexible for practical use. Therefore, in spite of the improvement in the heat resistance, there is no problem solving, therefore values of only 0.6 to 5 N / cm are aimed for in the invention. With the extremely low melt indices of the polyolefins used, the method of extrusion described can hardly be carried out on a production extrusion system, especially not for a practical thin film of 100 μm or less, and certainly not when used in combination with the high amounts described platelet-shaped, finely divided filler. The combination with the high viscosity-increasing red phosphorus further complicates the processability. Therefore, despite massive demand from the Japanese auto industry, the products have not yet reached series maturity. Surprisingly, the problem can be solved if, instead of conventional filler, the spherical, coarse-particle magnesium hydroxide according to the invention, preferably produced by grinding, is used, in particular if, in addition, the mainly preferred polyolefin has a significantly higher melt index, lower flexural modulus and high softening point. In the document discussed, the melt index of the polymers characterizing the invention is below 1, whereas the value in the present invention for extrusion above 1 is preferably between 5 and 15 g / 10 min. The breakdown voltage and aging stability of the examples from the document discussed are also in need of improvement, which can be achieved by the size and shape of the filler according to the invention (has a positive effect on inhomogeneity and micro-hole formation) or by adding certain anti-aging agents.

Both approaches from the publications mentioned build on the well-known synergistic flame retardant effect of red phosphorus with magnesium hydroxide. However, the use of elemental phosphorus has considerable disadvantages. 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 to black products can be produced, but wrapping foils are used in a wide range of colors for color coding. The present invention does not rule out the use of red phosphorus, but the excellent fire behavior is preferably achieved by using a particularly high amount of magnesi hydroxide, which requires the use of the special quality according to the invention, and by a particularly high amount of soot is further increased.

WO 03/070848 A1 describes a winding tape made of a reactive polypropylene and 40 phr. The low magnesium hydroxide content means that there is hardly any flame resistance. The use of carbon black or spherical magnesium hydroxide has not been described. DE 203 06 801 U1 describes polyurethane, such a product is far too expensive for the usual applications described above. There is no further information on the use of anti-aging agents or magnesium hydroxide.

In spite of the disadvantages mentioned, the prior art documents mentioned do not list any films which also solve the further requirements such as hand tearability, heat resistance, compatibility with polyolefin cable insulation or sufficient unwinding force. In addition, the processability in film manufacturing processes, high fogging value and dielectric strength remain questionable.

The task therefore remains to find a solution for a wrapping film that combines the advantages of flame retardancy, abrasion resistance, tension resistance and the mechanical properties (such as elasticity, flexibility, hand tearability) of PVC wrapping tapes with the halogen-free nature of textile wrapping tapes and one more has superior heat aging resistance, it being necessary to ensure that the film can be produced on an industrial scale and that a high dielectric strength and a high fogging value are necessary in some applications. It is another object of the invention to provide filled, soft wrapping foils which are flame-retardant and free of halogens and enable safe and rapid wrapping, marking, protecting, isolating, sealing or bundling, in particular of wires and cables, the disadvantages of the prior art Technology does not occur or at least does not occur 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. Then there is also the task of finding polypropylene copolymers with additive combinations which not only achieve the heat resistance of PVC but even exceed 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, the use of the wrapping film in a soft, flame-retardant Adhesive tape, other uses of the same, and processes for producing the wrapping film.

Accordingly, the invention relates to a filled, soft, halogen-free, flame-retardant wrapping film made of a polyolefin and magnesium hydroxide with (possibly irregular) spherical structure and a particle size in the μm range, preferably produced by grinding, in particular in combination with special polyolefins such as polypropylene elastomer with a low flexural modulus, the Thickness of the wrapping film is 30 to 200 μm and in particular 50 to 130 μm.

The information given in phr below means 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 (s) are taken into account.

The surface of the film according to the invention is preferably set slightly matt. This can be achieved by using a filler with a sufficiently large particle size or by a roller (for example embossing roller on the calender or matted chilli roll or embossing roller in the extrusion). When using particularly coarse-grained types of the magnesium hydroxide according to the invention, a matt surface results automatically.

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).

Surprising and unforeseeable for the person skilled in the art, such a wrapping film can be produced, in particular, from a special flame-retardant filler and polyolefin in combination with a polypropylene copolymer. Surprisingly, the thermal aging resistance is not worse compared to PVC as a high-performance material, it is comparable or even better.

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

Magnesium hydroxide with a spherical particle shape serves as the filler with the function as a flame retardant, although this does not have to be ideal, but rather irregularly spherical like river pebble, see FIG. 3. This shape is preferably obtained by grinding.

The commercially available magnesium hydroxides for flame retardant applications, on the other hand, have a more or less regular platelet structure, they are produced by precipitation from solution. Magnesium hydroxide in platelet form is not according to the invention; this applies to regular (for example hexahedron) and irregular platelets, see FIGS. 1 and 2.

The wrapping film according to the invention preferably contains 70 to 200 phr, more preferably 110 to 150 phr, of the magnesium hydroxide according to the invention as a flame retardant. The fire behavior also depends very much on other factors: • Adhesive coating

• Type of polyolefin

• Type and amount of soot as well

• other additives.

Therefore, the amount of the special magnesium hydroxide is chosen so high that the wrapping film is flame-retardant, i.e. slowly burning or self-extinguishing. The Rate of fire 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%.

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

The coating content is preferably between 0.3 and 1% by weight, based on magnesium hydroxide. Magnesium hydroxide, which was prepared by dry grinding in the presence of a free fatty acid, in particular stearic acid, is particularly preferred. The resulting fatty acid coating 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 synthetic precipitated magnesium hydroxide, the fatty acid must always be added in salt form because of its water solubility. This is one of the reasons why a ground magnesium hydroxide with free fatty acid is preferred over a precipitated with fatty acid salt for the wrapping film according to the invention.

Ground magnesium hydroxides are particularly preferred, since the desired spherical structure can be easily obtained with a suitable process and raw material. Examples are brucite (natural magnesium hydroxide mineral), kovdorskite (magnesium hydroxide phosphate) and hydromagnesite (magnesium hydroxide carbonate), with brucite being the most preferred. The content of other anions such as phosphate or carbonate in mol% should be significantly lower than that of hydroxide. The purity content of the magnesium hydroxide is preferably at least 90% by weight.

In addition to these mineral magnesium hydroxides, synthetic magnesium hydroxide can also be used for the wrapping foils according to the invention, provided that has claimed structure, however, synthetic magnesium hydroxides with a spherical structure are currently not sufficiently available in commercial quantities, since the production process is currently not as economical as rapid precipitation, but this leads to platelet-shaped and finely divided crystals.

Admixtures of magnesium carbonates such as dolomite [CaC0 ₃ ^• MgC0 ₃ , M _r 184.41], magnesite (MgCO ₃ ), huntite [CaC0 ₃ - 3 MgC0 ₃ , M _r 353.05] or hydrotaicit (aluminum-magnesium mixed crystal with carbonate and hydroxide in the crystal lattice) are permitted. A content of calcium carbonate (as a pure compound or in the form of a mixed crystal with calcium and magnesium and carbonate and optionally hydroxide) even turned out to be advantageous for aging, a proportion of 1 to 4% by weight of calcium carbonate being regarded as favorable ( the analytical calcium content is converted to pure calcium carbonate). The calcium and carbonate content of brucite is present in many deposits of natural magnesium hydroxide as an impurity in the form of chalk, dolomite, huntite or hydrotaicit, but can also be specifically added to the magnesium hydroxide. The positive effect may be due to the neutralization of acids. These arise, for example, from magnesium chloride, which is usually found as a catalyst residue in polyolefins (for example from the spheripol process). Acidic components from the adhesive coating can also migrate into the film and thus worsen aging. By adding calcium stearate, an effect similar to that of calcium carbonate can be achieved, but the addition of larger amounts reduces the adhesive strength of the adhesive coating and in particular the adhesion of such an adhesive layer to the back of the winding film in the case of such winding tapes.

Magnesium hydroxide with an average particle size d ₅₀ of at least 2 μm and in particular of at least 4 μm is particularly suitable. Usual wet-precipitated magnesium hydroxides are too fine, usually the average particle size d ₅₀ is 1 μm and below. The d ₉ value of the magnesium hydroxide according to the invention should not be more than 25 μm in order to avoid the occurrence of holes in the film and insufficient elongation at break, which can be achieved, for example, by sieving.

A content of particles with a diameter of 10 to 25 μm gives the film a pleasant looking matt effect and good hand tearability, which conventional fine-particle magnesium hydroxides remains unsuccessful. Polyolefin films are smooth and therefore have a typical "plastic gloss", whereas the PVC films that are customary for wrapping films are matt due to the filling of ground chalk and sandblasted calender rollers.

However, the person skilled in the art suggests the use of the commercially available fine-particle synthetic magnesium hydroxide, since it is very pure, cannot lead to specks and holes in the film due to the small particle size, and it is reasonable to assume that the flame resistance should tend to be better than that of large particles , Surprisingly, it turns out that compounds made from ground magnesium hydroxide with larger spherical particles can be processed better in the calendering and extrusion process than compounds made from magnesium hydroxide with small platelet-shaped particles. Fine-particle platelet-shaped magnesium hydroxide gives significantly higher melt viscosities than coarser spherical magnesium hydroxide, which is associated with corresponding processing problems. These include, for example, low emissions and the formation of bubbles and holes due to thermal decomposition of the magnesium hydroxide with high friction. The problem can be countered with polymers with a high melt index (MFI), but this worsens the mechanical stability of the melt, which is particularly important for bladder extrusion and calendering. In the preferred embodiment, the film on the calender is easier to pull off the rollers, or the tube is better in the case of blown extrusion (no breaks in the melt tube). Due to the better processability of the magnesium hydroxide according to the invention, the filler content can even be increased, which leads to better flame resistance, but it should also be noted that the polyolefin should be correspondingly softer.

The spherical, coarse-particle magnesium hydroxide filler can be combined with other flame retardants or fillers, for example with nitrogen-containing flame retardants. Examples of these are dicyandiamide, melamine cyanurate and sterically hindered amines such as, for example, from the class of HA (L) S.

For applications under the influence of high service temperatures, the traces of heavy metals from natural magnesium hydroxide can adversely affect aging, which can be achieved by using the special aging protection combinations mentioned below. is prevented. Therefore, when using natural magnesium hydroxide according to the invention, the addition of a suitable anti-aging combination is preferred.

The specific surface area (BET) of the magnesium hydroxide according to the invention is preferably at least 5 m ² / g.

Red phosphorus works synergistically with magnesium hydroxide and can therefore be used. However, it has disadvantages which are not detrimental to the invention in individual cases. It is not possible to produce colored products, only black and brown products, when compounding, phosphine is produced, which requires protective measures to avoid health risks, and strong white smoke is produced in the event of a fire. Red phosphorus is therefore preferred and the proportion of filler is increased or an oxygen-containing polymer is used or added.

Organic and inorganic phosphorus compounds in the form of the known flame retardants, such as those based on triaryl phosphate or polyphosphate salts, have an antagonistic effect in contrast to red phosphorus. In the preferred embodiments, bound phosphorus is therefore dispensed with unless it is a sensible phosphite with an anti-aging effect. These should not allow the content of chemically bound phosphorus to rise above 0.5 phr.

To achieve these force values, in addition to the special magnesium hydroxide mentioned, the wrapping film preferably contains a soft polyolefin, preferably with a flexural modulus of less than 900 MPa, particularly preferably 500 MPa or less and in particular 80 MPa or less. This can be a soft ethylene homopolymer or ethylene or propylene copolymer. No restrictions are imposed on the monomer (s) of the polyolefin, but α-olefins such as ethylene, propylene, butene- (1), isobutylene, 4-methyl-1-pentene, hexene, octene, decene or dodecene are preferred , Copolymers with three or more monomers and copolymers with polar monomers such as vinyl acetate, vinyl alcohol, vinyl butyral, acrylates and methacrylates are included within the meaning of the term polyolefin.

To achieve heat resistance, the film can be crosslinked or contain at least one polyolefin with a crystallite melting point of at least 120 ° C., in particular a polymer polymer based on propylene. Examples of suitable polyolefins are, for example, soft propylene or ethylene polymers such as LDPE, LLDPE, metallocene PE, EPM or EPDM with a density of, for example, 0.86 to 0.92 g / cm ^3, preferably of 0.86 to 0 , 88 g / cm ³ . Suitable comonomers for reducing the crystallinity, ie for reducing the flexural modulus, are α-olefins such as ethylene, propylene, butene- (1), isobutylene, 4-methylM-pentene, hexene, octene, decene or dodecene. If the crystallite melting point of the main polyolefin used is below 12 ° C, which is the case with most soft ethylene copolymers, the heat resistance is preferably increased by blending with a polymer with a higher crystallite melting point or by chemical or radiation-chemical crosslinking. EB (electron beams), UV (using photoinitiators or unsaturated crosslinking promoters), silane and peroxide crosslinking are suitable for this. Chemical crosslinking agents such as alkylphenol resins, sulfur or sulfur-containing crosslinking agents are also suitable for EPDM. A PP homopolymer or PP copolymer is preferred as the blending component to increase the heat resistance, in particular block copolymers, random copolymers and very particularly preferably the particularly soft polypropylenes described in more detail above. Heat resistance is important in applications on ventilation pipes, display coils or vehicle cables because of the risk of melting.

The term polyolefin in the sense of this invention also includes olefin copolymers with one or more cycloolefinic, aromatic or oxygen-containing comonomers such as ethylene acrylate (for example EMA, EBA, EEA, EAA, ethylene-acrylic acid and its salts), polyethylene vinyl alcohol, ethylene vinyl acetate, ethylene styrene -Interpolymer or COC (cycloolefin copolymer derived from ethylene and dicyclopentadiene). As is known to the person skilled in the art, oxygen-containing copolymers have an improved fire behavior compared to polyethylene or polypropylene. They are therefore also proposed as additives for blends of other polyolefins and the magnesium hydroxide according to the invention. This also applies to olefin-free nitrogen- or oxygen-containing polymers as synergists. These are, for example, polyamides and polyesters with a sufficiently low softening point (suitable for the processing temperature of polypropylene), polyvinyl acetate, polyvinyl butyral, vinyl acetate-vinyl alcohol copolymer and poly (meth) acrylates. The person skilled in the art considers these strongly polar materials to be incompatible with polyolefins. Surprisingly, this is not a problem with the mixture of special copolymer and flame-retardant filler according to the invention. Before- Homo- and copolymers of vinyl acetate and (meth) acrylates are added, which can also be crosslinked. These can also have a core-shell structure, for example a core made from polyacrylates of alcohols with 2 to 8 carbon atoms and a shell made from polymethyl methacrylate. In particular, acrylate impact modifiers (which are used for the modification of PVC) and dispersion powders based on vinyl acetate (for example with a polyvinyl alcohol shell, such as those used as modifiers for gypsum and cement products) turned out to be particularly suitable. since they bring about a significant improvement in fire behavior even in small quantities, do not significantly impair the flexibility of the wrapping film and, despite their polarity, do not increase the adhesion of the melt to calender or cooling rolls. Another possibility is the use of polyolefins, in which the oxygen is introduced by grafting (for example with maleic anhydride or a (meth) acrylate monomer).

In a preferred embodiment, the proportion of oxygen based on the total weight of all polymers is between 0.7 and 10 phr (also corresponds to% by weight), in particular 5 to 8 phr. The nitrogen- or oxygen-containing polymer can also be used as a coextrusion layer to improve the flame resistance. Soft hydrogenated random or block copolymers of ethylene or (optionally substituted) styrene and butadiene or isoprene are suitable to bring the flexibility, the force at 1% elongation and in particular the shape of the force-elongation curve of the wrapping film into the optimal range ,

However, the crystalline melting point of the polyolefin should not be below 120 ° C, as is the case with EPM and EPDM, because there is a risk of melting in applications on ventilation pipes, display coils or vehicle cables, but this does not exclude that such polymers can be used to adjust the mechanical properties can be used in addition to a higher melting polyolefin.

Preferred polyolefins are soft polypropylene copolymers, because on the one hand they have sufficient heat resistance against softening, and on the other hand they are characterized by excellent absorption capacity of large amounts of filler (presumably low flexural modulus and filler absorption are related to the crystalline fraction). The polypropylene polymer has a crystallite melting point of 120 to 166 ° C and has a flexural modulus of 900 MPa or less, preferably 500 MPa or less, and more preferably 800 MPa or less. The crystallite melting point of the polypropylene copolymer is preferably below 148 ° C and particularly preferably below 145 ° C. With a crystallite melting point above 120 ° C, no crosslinking is required. Such polypropylene copolymers make it possible to use large amounts of filler to a particular extent. In combination with ground magnesium hydroxide with a relatively higher d ₅₀ value, the filler content can be set particularly high without the wrapping film becoming too stiff and inflexible for the application.

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.

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 comonomer (s) of propylene in the polypropylene copolymer, but α-olefins such as ethylene, 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 also be modified by grafting, for example with maleic anhydride or acrylate monomers, for example to improve the processing behavior or the mechanical properties. 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. When using random copolymer 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 processes can be used for the production, examples being the gas phase, Cataloy, Spheripol, Novolen and Hypol processes, which are described in Ullmann's Encyclopedia of Industrial Chemistry, 6th edition, Wiley-VCH 2002 are.

These preferred polyolefins in the form of soft polypropylene copolymers can be mixed by adding soft copolymers such as SEBS, SEPS, metallocene polyethylene, EPM, EPDM or amorphous or low-crystalline EVA, EBA, EMA etc. to improve the mechanical properties or else to positively influence the processing properties. The blending components can be modified by grafting, for example it turns out that polyolefins grafted with maleic anhydride or acrylic acid substantially facilitate the incorporation of magnesium hydroxide. In larger quantities, however, they lead to drastic cost increases and the film sticking to the calender rolls. In contrast to the conventional magnesium hydroxides, the magnesium hydroxides according to the invention require no or only small amounts of such grafted polymers in order to achieve high strength and good homogeneity and processability.

The preferred melt index of the main polyolefin component for extrusion processing is between 1 and 20 g / 10 min, in particular between 5 and 15 g / 10 min.

Polyolefins with a melt index of less than 5 and especially less than 1 g / 10 min have so far not been able to be processed into thin, non-oriented films with large amounts of filler. About- Surprisingly, a solution for processing is also found for such polymers, at least when using the filler according to the invention, in the form of the calendering process. For this, the preferred melt index of the main polyolefin component is below 5 g / 10 min, particularly preferably below 1 g / 10 min and in particular below 0.7 g / 10 min. Polyolefins with such low melt indices have excellent heat resistance, because even above the melting point the melt is mechanically stable due to the high molecular weight, as storage tests at 170 ° C surprisingly show (see examples). When specifying the melt index, it is not taken into account that the melt index of ethylene-containing copolymers is usually specified at 190 ° C and for polypropylene at 230 ° C. If several polyolefins are used, they differ in the specified melt index preferably by less than a factor of 6 and particularly preferably by less than a factor of 3.

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.

The main object of the present invention is the absence of halogens and volatile plasticizers. As stated, the thermal requirements increase, so that an additional resistance to conventional PVC wrapping films or the PVC-free film wrapping tapes currently being tested is to be achieved. Therefore, the present invention in this regard will be described in detail below.

The wrapping film according to the invention has a thermal stability of at least 105 ° C. after 3000 hours, which means that after this storage there is still an elongation at break of at least 100%. It should also have an elongation at break of at least 100% after 20 days of storage at 136 ° C (rapid test) or a heat resistance of 170 ° C (30 min.). In an excellent embodiment with the described antioxidants and optionally also with a metal deactivator, 125 ° C is reached after 2000 hours or even 125 ° C after 3000 hours. Classic PVC wrapping films based on DOP have a thermal stability of 85 ° C (passenger compartment), high-performance products based on polymer plasticizers reach 105 ° C (engine compartment).

In addition, the wrapping film must be compatible with a polyolefin-based cable sheathing, that is, after storage of the cable / wrapping film assembly, neither embrittlement of the wrapping film nor the cable insulation may occur. By selecting one or more suitable antioxidants, compatibility at 105 ° C., preferably 125 ° C. (2000 hours, in particular 3000 hours) and short-term heat resistance of 140 ° C. (168 hours) can be achieved.

A further prerequisite for adequate short-term heat resistance and heat resistance is an adequate melting point of the polyolefin (at least 120 ° C.) and an adequate mechanical stability of the melt somewhat above the crystallite melting point. The latter is guaranteed by a melt index of at most 20 g / 10 min with a filler content of at least 80 phr or of at most 5 g / 10 min with a filler content of at least 40 phr. However, aging stabilization is crucial to achieve oxidative resistance from 140 ° C, which is achieved in particular by secondary antioxidants such as phosphites.

Compatibility between the wrapping film and the other wiring harness components such as plugs and creasing tubes is also desirable and can also be achieved by adapting the recipes, especially with regard to the additives. A negative example is the combination of an unsuitable polypropylene wrapping film with a copper-stabilized polyamide corrugated pipe, in which case both the corrugated pipe and the wrapping film become brittle after 3,000 hours at 105 ° C.

The use of the right anti-aging agents plays a special role in achieving good aging stability and tolerance. The total amount of stabilizer must also be taken into account, since previous attempts to manufacture such winding tapes used no or only less than 0.3 phr (x phr means x parts per 100 parts polymer or polymer blend) anti-aging agents, as was also the case with the production of other films is common. The winding tapes according to the invention should 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 being present in different molecules or being combined in one molecule. Optional stabilizers such as metal deactivators or light stabilizers are not included in the stated quantities.

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), the two functions also in one Molecule can be united, 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 (especially> 700 g / mol), with a phosphitic secondary antioxidant (especially with a molecular weight> 600 g / mol) prefers. 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 • Sulphurous function:

CAS 693-36-7, 123-28-4, 16545-54-3, 250O-88-1

• Phosphitic function:

CAS 31570-04-4, 26741-53-7, 80693-0O-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 ID activators 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 _J 4-triazole (Palmarole ADK STAB CDA-1), N, N'-bis [3- (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionyl] hydrazide (Palmarole 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 particularly important for the wrapping film according to the invention, since phenolic antioxidants alone or even in combination with sulfur-containing costabilisers generally do not make it possible to achieve products which are suitable for practical use. This is the case with calender processing, in which a relatively long period of ingress of atmospheric oxygen is unavoidable The use of phosphite stabilizers as practically indispensable for a sufficient heat aging stability of the product. Even in the case of extrusion processing, the addition of phosphates has a positive effect on the aging test 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 and metal deactivator as described is particularly useful. This applies in particular to applications with high temperature loads (for example as a cable wrapping film in the engine compartment of motor vehicles or as an insulation winding of magnetic coils in television or PC screens).

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. The thermal aging stability is surprisingly higher if the carbon black (for example in the form of a masterbatch) is only added after the polypropylene polymer has been mixed with the anti-aging agents (antioxidants). This advantage can be used by first compounding the polymer, anti-aging agent and filler and adding the carbon black as a masterbatch to an extruder in the film production line (calender or extruder). An additional benefit is that no complex cleaning of soot residues is required when changing the product on the compounder (stamp kneader or extruder such as twin-screw extruder or planetary roller extruder). Surprisingly for the person skilled in the art, unusually high amounts of soot masterbatch can also be added to the film line without any problems, that is to say not only 1 to 2, but even 15 to 30 phr. All types such as, for example, gas black, acetylene black, thermal black, furnace black and flame black can be used, carbon black being preferred, even though furnace black is common for coloring films. For Optimum aging is preferred for soot types with a pH in the range from 6 to 8, particularly flame black.

The following methods are preferred and claimed for incorporating the filler: Mixing of polymer and filler in a stamp kneader in batch operation or continuously (for example from Banbury), part of the filler is preferably added when another part is already homogenized with the polymer has been.

Mixing of polymer and filler in a twin-screw extruder, a pre-compound being produced with part of the filler, which compound is mixed with the rest of the filler in a second compounding step.

Mixing of polymer and filler in a twin-screw extruder, the filler not being introduced into the extruder at one point, but in at least two zones, for example by using a side feeder.

The wrapping film is produced on a calender or by extrusion, for example in the blowing or casting process. These processes are described, for example, in Ullmann's Encyclopedia of Industrial Chemistry, 6th edition, Wiley-VCH 2002. The compound from the main components or all of the 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 a film extrusion system or melted and processed in an extruder, kneader or rolling mill in a calender system. 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 films made from the compound reach 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 an extrusion system or a 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. For this reason, the calendering process is particularly preferred. 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 adhesive coating, the information given here about 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 with a pressure-sensitive adhesive strip on each side edge. 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 acid esters, butadiene or Be 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 mixed with one or more additives such as tackifiers (resins), plasticizers, fillers, flame retardants, pigments, UV absorbers, light stabilizers, anti-aging agents, photoinitiators, crosslinking agents or crosslinking promoters. Tackifiers are, for example, hydrocarbon resins (for example polymers based on unsaturated C ₅ or C ₉ monomers), terpene phenol resins, polyterpene resins made 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 Ullmann's encyclopedia of industrial chemistry, Volume 12, pages 525 to 555 (4th edition), Weinheim). Resins without readily oxidizable double bonds, such as terpene-phenolic 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, carbon black, 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 made from butene and / or polyvinyl ether, acrylic acid esters, acrylic acid esters 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 the tendency towards deformation of 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 coextrusion, 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 polyvinyl stearyl carbamate, stearyl compounds of transition metals such as Cr or Zr, ureas from polyethylene imine 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 with all straight or branched alkyls or alkenyls with a C number of at least 10, such as octadecyl.

Descriptions of the customary adhesives and backing coatings and primers can be found, for example, in "Handbook of Pressure Sensitive Adhesive Technology", D. Satas, (3rd edition). The backing primer and adhesive coatings mentioned are possible in one embodiment 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. Alternatively, a wrapping film is claimed, in which the logs are 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.

Annealing 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 not very resistant to shear 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 rolling force through tempering or physical surface treatment ling is not necessary for soft PVC wrapping tapes, since the adhesives usually used have a sufficiently high adhesion to the polar PVC surface. In the case of polyolefin wrapping films, the importance of rear 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 necessary in comparison to PVC film provide sufficient stretch when unrolling for the application. The preferred embodiment of the wrapping film is therefore produced by tempering or physical surface treatment in order to achieve excellent unwinding force and elongation during unwinding, the unwinding 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 at least 3 days beforehand, particularly preferably at least 7 days before the coating, in order to achieve recrystallization so that the rolls have no 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. Rough cut edges are produced during the production of the winding film rolls, which, when viewed microscopically, form cracks in the film, which then apparently promote tear propagation. 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 in production width and sales length). The elongation at break can be adjusted by a suitable grinding of the blades and knives. 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 crack formation during the cutting process can be improved. 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 wrapping tapes with fabric, fleece and film backing (e.g. 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 at Pass divided by sharp blades) 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 cut-off 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 gelation during film production, which is an obstacle to an optimal production speed. In many cases, therefore, instead of standard PVC with a K value of 63 to 65, a higher material is used Molecular weight used, which corresponds to K values of 70 and more. The cut-off cut has a different reason for the wrapping films of polypropylene according to the invention than for those made of PVC.

The wrapping film according to the invention is excellently suitable for wrapping elongated material such as ventilation pipes in air conditioning, field coils or cable sets in vehicles, since the high flexibility ensures good conformability on wires, cables, rivets, beads and folds.

Today's occupational hygiene and ecological requirements should be 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 retardancy. 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 and poor flame resistance 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 and halogen-containing additives, but by using a mixture made of a soft polyolefin (with a low flexural modulus) and a magnesium hydroxide with (irregular) spherical structure and a particle size in the μm range.

Previous attempts to replace wrapping films made of soft PVC with other materials have so far not been implemented commercially. Either insufficient flame retardancy was not achieved or a large amount of conventional flame retardants such as precipitated aluminum or magnesium hydroxide led to massive processing problems and, on top of that, inflexible materials or with small amounts of filler low flame resistance. In addition, unstretched polyolefin films cannot be torn by hand. It is therefore particularly surprising that mixtures of polyolefins and ground magnesium hydroxide with an (irregular) spherical structure and a particle size of several μm are not only easy to process, so that the amount of magnesium hydroxide can even be increased compared to conventional precipitated platelet-shaped, very fine-particle synthetic magnesium hydroxide , so that the flame retardancy can be further improved than previously thought to the expert. The magnesium hydroxide used according to the invention also results in optimum hand tearability, provided the average particle size d _{50 is} at least 2 μm, preferably at least 4 μm (otherwise difficult to tear) and the d ₉₇ value is not more than 25 μm (otherwise too brittle). When using the magnesium hydroxide according to the invention, the elongation at break is reduced compared to unfilled or with conventional filled films. When examining the patterns, it is noticeable that if the film is torn off quickly and in a practical manner after the wrapping process, clean tear-off edges form as in the case of soft PVC, whereas polyolefin films which are not filled or filled incorrectly only form long, constricted ends. Spherical calcium carbonate surprisingly behaves much worse than the filler according to the invention, which means that the special properties of spherical magnesium hydroxide were not obvious. The flexibility of a wrapping film is of paramount importance, since when used on wires and cables, not only is the winding wound spirally, but it is also necessary to wind it in a wrinkle-free manner at bifurcation points, plugs or fastening clips. In addition, it is desirable that the wrapping film elastically pull the cable harness together. This behavior is also necessary for sealing the ventilation pipes. These mechanical properties can only be achieved with a soft, flexible winding tape. The object of achieving the requirements for flexibility and high filler content (as an essential control variable for fire behavior) by selecting suitable flame retardants and suitable polyolefins was achieved according to the invention. The task of developing a wrapping tape made of polyolefin is much more difficult than with PVC, since PVC requires little or no flame retardants and the flexibility can be largely adjusted by plasticizers in a known manner. In contrast to polyolefin, soft PVC film can basically be torn by hand because it is amorphous and not partially crystalline. 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 according to ISO 1183 and the bending mod! determined 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 comparable as a number.) The melt index is tested 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 MTMI 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 content of magnesium hydroxide and calcium carbonate in the filler is determined from the content of magnesium oxide and calcium oxide in the ignition residue (ICP-AES).

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 a different 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 important factors.

Rating:

+++ = very light,

++ = good,

+ = still processable, - = difficult to process, = can only be torn off with great effort, the ends are unclean, = 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 commercially available conductors (cables) with polyolefin insulation (polypropylene or radiation-cross-linked polyethylene) for motor vehicles. For this purpose, test specimens are produced from 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% overlap. 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 were conditioned at 23 ° C and wound around a mandrel by hand in accordance with ISO / DIN 6722, the mandrel 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 stored at 170 ° C. for 30 minutes, cooled to room temperature for 30 minutes and wrapped with at least 3 turns with a 50% overlap around a mandrel with a diameter of 10 mm. Then the sample is 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 / 10 μm.

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

The following examples are intended to illustrate the invention without restricting its scope.

Content:

• Tabular compilation of the raw materials used for the tests

• Description of the examples • Tabular summary of the results of the examples

• Description of the comparative examples

• Tabular compilation of the results of the comparative examples Tabular compilation of the raw materials used for the tests (the measurement conditions and units are partly omitted, see test methods)

example 1

To produce the carrier film, 100 phr polymer A, 10 phr Vinnapas B 10, 150 phr Apymag 80, 10 phr flame black 101, 0.5 phr Irganox MD 1024, 0.8 phr Irganox 101 O, 0.8 are first in a co-rotating twin-screw extruder phr Irganox PS 802 and 0.3 phr Irgafos 168 compounded. The Magnifin is added to 1/3 in zones 1, 3 and 5.

The compound melt is fed from the die of the extruder to a rolling mill, from there through a strainer and then fed via a conveyor belt into the nip of an "inverted L" type calender. With the help of the calender rolls, a film is produced at a speed of 80 m / min with a smooth surface in a width of 1500 mm and a thickness of 0.08 mm (80 μm) and recrystallized on heat-setting rollers. The film is stored for one week, leveled on the coating system with rollers at 60 ° C. to improve the flatness and after corona treatment with an aqueous acrylic pressure sensitive adhesive Primal PS 83 D applied with a doctor blade with an application weight of 24 g / m ^2. The adhesive layer is dried in the drying tunnel at 70 ° C, the finished wrapping film is made into rods with 33 m run length on 1- Inch core (25 mm) The cutting is done by parting off the bars using a fixed blade with a not very acute angle (strai ght knife) in 29 mm wide rolls. As in the examples below, an automatic cut-off is used for the reasons given in the description of the invention. This self-adhesive wrapping film shows good flexibility despite the high filler content. Furthermore, very good fire properties are achieved even without the addition of an oxygen-containing polymer. The aging resistance and compatibility with PP and PA cables and polyamide corrugated pipe are outstanding.

Example 2

The preparation is carried out analogously to Example 1 with the following changes: The compound consists of 100 phr polymer A, 120 phr brucite 15μ, 15 phr flame black 101, 0.8 phr Irganox 1010, 0.1 phr Irganox PS 802, 0.1 phr Sumilizer TPM , 0.1 phr Sumilizer TPL-R, 0.1 phr Sumilizer TP-D, 0.3 phr Irgafos 168 and 1 phr Irganox MD 1024. The brucite is added in zones 1 and 5 to Vz.

The carrier film produced therefrom is subjected to a one-sided flame pretreatment and, after 10 days of storage, is coated with Acronal DS 3458 using a roller applicator at 50 m / min. The temperature load on the carrier is reduced by a cooled counter-pressure roller. The mass application is approx. 35 g / m ² . A suitable crosslinking is achieved in-line prior to winding up by irradiation with a UV system equipped with 6 medium-pressure mercury lamps of 120 W / cm each. The irradiated web is converted into rods with a run length of 33 m over 1 1/4. Zol! Core (31 mm) wound. The bars are annealed in an oven at 60 ° C for 5 hours to increase the unwinding force. The cutting is done by parting the rods with a fixed blade (straight knife) into 25 mm wide rolls.

After 3 months storage at 23 ° C from the film no Alterungsschutzm ^'exuded rttel. In comparison, the film from Example 1 has a light coating, which after analytical testing consists of Irganox PS 802.

This wrapping film is characterized by an even greater flexibility than that from example 1. The rate of fire is more than sufficient for the application. The film has a slightly matt surface. During the application, two fingers have to be placed in the core, which makes the application easier than in Example 1. Example 3

The preparation takes place analogously to Example 1 with the following changes: The compound consists of 80 phr polymer A, 20 phr Evaflex A 702, 120 phr Securoc B 10, 0.2 phr calcium carbonate, 10 phr flame black 101, 0.8 phr Irganox 1010, 0 , 8 phr Irganox PS 802 and 0.3 phr Irgafos 168.

The film is corona-treated in front of the winding station of the calender and applied to this side of the Rikidyne BDF 505 adhesive (with the addition of 1% by weight Desmodur Z 4470 MPA / X to 100 parts by weight of adhesive to dry content) at 23 g / m ² . The glue is dried in a heating channel and chemically cross-linked, wrapped in jumbos at the end of the dryer, lightly corona-treated after 1 week on the non-coated side and wrapped in rods with a 25 m length. These are stored in an oven at 100 ° C for 1 hour. The cutting is done by parting the rods using rotating, slightly blunt knives (round blades) in rolls of 15 mm width.

This wrapping film has balanced properties and shows a slightly matt surface. The holding power is over 2000 min (measurement then stopped). The elongation at break is 36% lower than for samples with a blade cut. The rolling force is 25% higher than for samples without tempering.

Example 4

The production takes place analogously to example 1 with the following changes:

The compound consists of 100 phr polymer A, 120 phr Maglux MK, 10 phr flame black

101, 2 phr Irganox 1010, 1.0 phr Irganox PS 802, 0.4 phr Irgafos 168.

After one week of intermediate storage, the film is flame-treated on one side and coated with 30 g / m ² (dry application) of Airflex EAF 60. The web is pre-dried with an IR lamp and finally dried in a channel at 100 ° C. The tape is then wound into jumbos (large rolls). In a further step, the jumbos are unwound and the uncoated side of the wrapping film is subjected to a weak corona treatment in order to increase the unwinding force, and then in a cutting machine Blunt squeeze cut (crush cutting, debris cut) to 33 m long rolls in 19 mm width on 1 ¹ inch core (37 mm inner diameter) processed. The elongation at break is 48% lower than for samples with a blade cut. The rolling force is 60% higher than for samples without corona treatment. During the application, two fingers have to be placed in the core, which facilitates the winding compared to example 1.

Example 5

The compound is produced using a stick extruder (Buss) without soot and with underwater pelletizing. After drying, the compound is mixed with the soot masterbatch in a concrete mixer.

The carrier film is produced on a blown film extrusion system with the following recipe: 100 phr polymer B, 100 phr brucite 15μ, 20 phr of a masterbatch made of 50% flame black 101 and 50% polyethylene, 0.8 phr Irganox 1076, 0.8 phr Irganox PS 800, 0.2 phr Ultranox 626, 0.6 phr Naugard XL-1.

The film tube is slit and opened with a triangle to form a flat web and passed over a heat setting station, corona-treated on one side and stored for one week for recrystallization. The film is fed to the coating system via 5 preheating rollers for leveling (improving the flatness), otherwise the coating is carried out with pressure sensitive adhesive analogous to Example 1, the rods are annealed at 65 C for 5 hours and cut analogously to Example 1.

Without heat-setting, the film shows significant shrinkage (5% in width, not measured lengthways) during the drying process. The flatness of the freshly produced film is good, it is coated immediately after extrusion, unfortunately the rolls are already clearly telescoped after three weeks of storage at 23 ° C. This problem cannot be eliminated by tempering the bars (10 hours at 70 ° C).

The film is then stored for one week before coating, the rolls are only partially telecopied, but the flatness is so poor during coating and the application of adhesive is so uneven that preheating rollers have been installed in the system. The films are characterized by good heat resistance, i.e. without melting and embrittlement, with an additional storage period of 30 minutes at 170 ° C.

Example 6

The production takes place analogously to Example 1 with the following changes: The film contains 80 phr polymer C, 20 phr Escorene UL 00119, 130 phr Hydrofy GS-5, 15 phr flame black 101, 0.8 phr Irganox 1010, 0.8 phr Irganox PS 802 , 0.3 phr Irgafos 168 and 1 phr Keromet MD 100.

This carrier film is corona treated on one side and stored for one week. The pretreated side is coated with an adhesion promoter layer made of natural rubber, cyclo-rubber and 4,4'-diisocyanatodiphenylmethane (solvent toluene) of 0.6 g / m ² and dried. The adhesive coating is applied directly to the adhesive layer by means of a comma knife with an application weight of 18 g / m ² (based on dry substance). The adhesive consists of a solution of a natural rubber adhesive in n-hexane with a solids content of 30 percent by weight. This consists of 50 parts of natural rubber, 10 parts of zinc oxide, 3 parts of rosin, 6 parts of alkylphenol resin, 17 parts of terpene-phenol resin, 12 parts of poly-ß-pinene resin, 1 part of Irganox 1076 antioxidant and 2 parts of mineral oil. The coating is dried in the drying tunnel at 100 ° C. The film is cut immediately behind in a compound cutting machine with a knife bar with sharp blades at a distance of 19 mm to rolls on standard adhesive tape cores (3 inches).

Despite the high proportion of filler, this wrapping film is characterized by very high flexibility, which is reflected in a low force value at 1% elongation. This wrapping film has mechanical properties similar to those of soft PVC wrapping tapes, although it is even superior in terms of flame resistance and heat resistance. The holding power is 1500 min and the rolling force at 30 m / min (not 300 mm / min) is 5.0 N / cm. The fogging value is 62% (presumably due to the mineral oil of the adhesive). Due to the large roll diameter, the roll can only be pulled through diagonally between the winding board and the wiring harness, which creates folds in the winding. Example 7

The compounds for the individual layers of the film are produced without soot in a kneader with an extruder and underwater granulation. The mixing time to homogenization is 2 minutes, the total kneading time to discharge into the granulating extruder is 4 minutes. In the case of the compound for layers 2 and 3, one half of the filler is added at the beginning and the other half after 1 minute. After drying, the compound granules are mixed with the soot masterbatch in a concrete mixer and fed to a 3-layer coextrusion system using the cast process (die width 1400 mm, melt temperature at the die head 190 ° C., chill roll temperature 30 ° C., speed 30 m / min).

The carrier film has the following recipe structure:

Layer 1:

15 μm 100 phr Evaflex P 1905, 40 phr martinite T3, 20 phr of a masterbatch made from 50% flame black 101 and 50% polyethylene, 0.4 phr Irganox 1076, 0.2 phr Irgafos 168 and 1 phr ADK STAB CDA-1

Layer 2:

40 μm: 100 phr polymer B, 120 phr martinite T3, 20 phr 20 phr of a masterbatch made of 50% flame black 101 and 50% polyethylene, 0.8 phr Irganox 1076, 0.8 phr Irganox PS 800, 0.2 phr Irgafos 168 and 1 phr ADK STAB CDA-1

Layer 3:

40 μm like layer 2

Layer 4

15 μm: 100 phr Escorene UL 02133, 0.4 phr Irganox 1076, 0.2 phr Irgafos 168

Layer 5

20 μm levapren 450 Due to the problems encountered with the blown film, the film is heat set. After one week of intermediate storage at 23 ° C., the film is coated as in Example 1, but using the leveling rollers. The wrapping film obtained in this way is wound into bars with a run length of 20 m, which are annealed at 40 ° C. for one week. The cutting is done by parting the rods with a fixed blade (straight knife).

In a preliminary test, a mixing time of 2 min was chosen, the film is homogeneous (no specks of filler), but the breakdown voltage is only 3 kV / 100μm. Therefore, the mixing time is increased despite the risk of degradation (the melt index as a measure of the degradation increases only slightly due to the longer time due to the use of phosphite stabilizer). This material has no adhesive force on steel and little adhesion on the back. This is sufficient for the windings not to be able to move against each other, but end fixation with a pressure-sensitive adhesive wrapping film is necessary at the end of the winding.

Due to the tempering, the unwinding force increases so much that the wrapping film can be applied under slight tension. This embodiment is solvent-free and easy to manufacture because no coating is required.

Due to the colored layer 1, which contains little flame retardant: medium, the wrapping film shows almost no whitening when stretched. The fogging value is 97%. During application, two fingers are to be accommodated in the core, which facilitates the winding compared to example 1, without the problems described in example 6 occurring.

The film distinguishes itself from the other examples and the comparative examples based on polyolefin and magnesium hydroxide in that at an elongation of more than 20% no whitening is discernible, since the outermost layer has only a small proportion of filler which is also well bound to the polar polymer , The fire behavior is nevertheless excellent due to the polar polymer content, and the polypropylene-containing layers prevent the film from melting. Properties of the examples

on patterns cut with blades Comparative Example 1

A conventional film for insulating tape from Singapore Plastic Products Pte. used under the designation F2104S. According to the manufacturer, the film contains approx. 100 phr (parts per hundred resin), suspension PVC with a K value of 63 to 65, 43 phr DOP (di-2-ethylhexyl phthalate), 5 phr triphasic lead sulfate (TLB, stabilizer), 25 phr ground chalk (Bukit Batu Murah Malaysia with fatty acid coating), 1 phr furnace black and 0.3 phr stearic acid (lubricant). The nominal thickness is 100 μm and the surface is smooth but matt.

On one side the primer Y01 from Four Pillars Enterprise / Taiwan is applied (analytically acrylate-modified SBR rubber in toluene) and then 23 g / m ^{2 of} the adhesive IV9 from Four Pillars Enterprise / Taiwan (main components that can be determined analytically: SBR and natural rubber, terpene resin and alkylphenol resin in toluene). Immediately after the dryer, the film is cut into rolls with a knife bar with sharp blades at a distance of 25 mm in a compound cutting machine.

The elongation at break after 3000 h at 105 ° C cannot be measured, since the pattern has broken down into small pieces due to plasticizer evaporation. After 3000 h at 85 ° C, the elongation at break is 150%

Comparative Example 2

Example 4 of EP 1 097 976 A1 is reworked.

The following raw materials are compounded in a kneader: 80 phr Cataloy KS-021 P, 20 phr Evaflex P 1905, 100 phr agshizu N-3, 8 phr Norvaexcel F-5, 2 phr Seast 3H and granulated, but the mixing time is 2 min ,

In a preliminary test, it was found that the melt index of the compound increased by 30% after 4 minutes of mixing (which may be due to the lack of a phosphite stabilizer or due to the greater mechanical degradation due to the extremely low melt index of the polypropylene polymer). Although the filler has been pre-dried and if there is an exhaust air device above the kneading compounder, a penetrating smell of phosphine develops on the system during kneading.

The carrier film is then produced by extrusion as described in Example 7 (all three extruders being fed with the same compound) via a slot nozzle and cooling roll in a thickness of 0.20 mm, the extruder speed being reduced until the film has a speed of Reached 2 m / min.

In a preliminary test, the speed of 30 m / min as in Example 7 could not be reached, since the system switches off due to excessive pressure (too high viscosity).

In a further preliminary test, the film is produced at 10 m / min, the mechanical data in the longitudinal and transverse directions indicated a strong longitudinal orientation, which is confirmed by a shrinkage of 20% in the running direction during coating. Therefore, the test is repeated at a still slow speed, which led to a technically perfect (including speck-free) but economically unsustainable film.

The coating is carried out analogously to Example 3, but with an adhesive application of 30 g / m ² (this adhesive has a composition similar to that of the original adhesive of the reworked patent example). Immediately after the dryer, the film is cut into 25 mm wide strips with a knife bar with sharp blades and wound together in rolls.

The self-adhesive wrapping tape is characterized by a lack of flexibility. Compared to Examples 5 and 6, the stiffness of Comparative Example 2 is 4030% and 19000% higher, respectively.

The stiffness is known to be from the thickness and the force at 1% elongation

(proportional to the modulus of elasticity). The sample shows a very good fire behavior due to the content of red phosphorus and the relatively high thickness (note: the LOI value was measured on the 0.2 mm thick sample with adhesive, the LOI of 30% in the cited patent document however, comes from a 3 mm thick test specimen without adhesive). Comparative Example 3

Example A of WO 97/05206 A1 is reworked.

The manufacture of the compound is not described. The components are therefore mixed on a twin-screw laboratory extruder with a length of 50 cm and an L / D ratio of 1:10: 9.59 phr Evatane 2805, 8.3 phr Attane SL 4100, 82.28 phr Evatane 1005 VN4, 74.3 phr Martinal 99200-08, 1.27 phr Irganox 1010, 0.71 phr AMEO T, 3.75 phr masterbatch black (made from 60% by weight polyethylene with MFI = 50 and 40% by weight Furnace Seast 3 H) , 0.6 phr stearic acid, 0.60 phr Luwax AL 3.

The compound is granulated, dried and blown into a tubular film on a laboratory system and slit on both sides. An attempt is made to coat the film after corona pretreatment with adhesive in the same way as in Example 1, but it has excessive shrinkage in the transverse and longitudinal directions, and the rolls can hardly be unwound after 4 weeks due to the excessive unwinding force.

An attempt is therefore made to coat with a non-polar rubber adhesive as in Example 6, but this fails because of the solvent sensitivity of the film. Since the specified text does not describe an adhesive coating, but the adhesive properties are desirable, the film is cut and wrapped in a silhouette between a set of pairs of two rotating knives into 25 mm wide strips.

The self-adhesive wrapping tape is characterized by good flexibility and flame resistance. However, the hand tearability is not sufficient. However, the low heat resistance, which leads to the melting of the adhesive tape when the aging tests are carried out, is particularly disadvantageous. Furthermore, the winding tape leads to a considerable shortening of the life of the cable insulation due to embrittlement. The high tendency to shrink is due to the low melt index of the compound. Problems can also be expected with a higher melt index of the raw materials, although this will significantly reduce the shrinkage, because heat setting is not provided in the document mentioned, despite the low softening point of the film. Since the product has no significant unwinding force, it can hardly be applied to wire bundles. The fogging value is 73% (presumably due to the paraffin wax). Comparative Example 4

Example 1 of EP 0 953 599 A1 is reworked.

The preparation of the compound is mixed as described on a single-screw laboratory extruder: 85 phr Lupolex 18 E FA, 6 phr Escorene UL 00112, 9 phr Tuftec M-1943, 63 phr Magnifin H 5, 1.5 phr magnesium stearate, 1 1 phr Novaexcel F 5, 4 phr carbon black FEF, 0.2 phr Irganox 1010, 0.2 phr Tinuvin 622 LD, whereby a clear release of phosphine can be smelled.

The film is produced as in Comparative Example 3.

However, the film has a large number of filler spots and small holes and the bubble tears off several times during the experiment. The breakdown voltage varies widely from 0 to 3 kV / 100 μ. The granulate is therefore melted and granulated again in the extruder for further homogenization. The compound now obtained has only a small number of specks. Coating and cutting is carried out analogously to example 1.

The self-adhesive wrapping tape is characterized by very good flame resistance due to the use of red phosphorus. Since the product has no rolling force, it can hardly be applied to wire bundles. The heat resistance is insufficient due to the low melting point.

Comparative Example 5

A UV-crosslinkable acrylic hot-melt adhesive of the Acronal DS 3458 type is applied to a textile carrier of the Maliwatt nonwoven thread type (80 g / m ² , fineness 22, black, thickness approx. 0.3 mm) using a nozzle coating 50 m / min applied. The temperature load on the carrier is reduced by means of a cooled counter-pressure roller. The mass application is approx. 65 g / m ² . A suitable crosslinking is achieved in-line prior to winding up by irradiation with a UV system which is equipped with 6 medium-pressure mercury lamps of 120 W / cm. The bales are cut in a silhouette (between a set of rotating knives slightly offset in pairs) assembled into rolls on standard 3-inch cores.

This wrapping tape is characterized by good adhesive properties as well as very good compatibility with various cable insulation materials (PVC, PE, PP) and corrugated pipes. From a technical point of view, however, the high thickness and the lack of hand tearability are very disadvantageous.

Comparative Example 6

Example 1 of US 5,498,476 A1 is reworked.

The following mixture is produced in a Brabender plastograph (mixing time 5 min.): 80 phr Elvax 470, 20 phr Epsyn 7506, 50 phr EDAP, 0.15 phr A 0750, 0.15 phr Irganox 1010.

The compound is pressed in a heated press between two sheets of siliconized polyester film to form test specimens 0.2 mm thick, which are cut into 25 mm wide and 25 cm long strips and wound up into a small roll on a core. According to the writing, there is no coating with adhesive.

This wrapping film has neither acceptable flexibility nor resistance to melting. Since the product has no rolling force, it can hardly be applied to wire bundles. It is difficult to tear by hand. The breakdown voltage is relatively high, since the mixture is obviously very homogeneous, the Brabender mixer mixes very intensively and the aminosilane could also make a positive contribution, for which the force-elongation curves of the cited patent document speak.

Comparative Example 7

Example 1 of WO 00/71634 A1 is reworked. The following mixture is produced in a kneader: 80.8 phr ESI DE 200, 19.2 phr Adflex KS 359 P, 30.4 phr calcium carbonate masterbatch SH3, 4.9 phr Petrothen PM 92049, 8.8 phr antimony oxide TMS and 17 , 6 phr DE 83-R.

The compound is processed into flat film on a cast laboratory system, pre-treated with corona, 20 g / m ² JB 720 coated, wound on bars with a 3-inch core and cut by parting with a fixed blade (manual feed).

This wrapping tape is characterized by PVC-like mechanical behavior, which means high flexibility and good hand tearability. The use of brominated flame retardants is disadvantageous. Furthermore, the heat resistance at temperatures above 95 ° C is low, so that the film melts during the aging and compatibility chain tests.

Comparative Example 8

The procedure is as in Example 1, but with the platelet-shaped Magnifin H 5 instead of Apymag 80. However, the calender speed had to be reduced to 50 m / min, since otherwise breaks would occur too often. This is probably more due to the visibly higher adhesion on the last calender roll than to the increased occurrence of small holes. The resulting film has positive properties, but the stiffness is noticeably higher than that. The breakdown voltage is slightly lower. The hand tearability is good, even though Example 1 behaves somewhat better.

* on patterns cut with blades

Claims

claims

1. Halogen-free wrapping film made of a polyolefin and magnesium hydroxide, characterized in that the magnesium hydroxide has an optionally irregular spherical shape and the thickness of the wrapping film is 30 to 200 μm and in particular 50 to 130 μm.

2. Wrapping film according to claim 1, characterized in that the magnesium hydroxide is produced by grinding.

3. Wrapping film according to claim 1 or 2, characterized in that the magnesium hydroxide has an average particle size d ₅₀ of at least 2 microns and in particular of at least 4 microns and that it is preferably sieved.

4. wrapping film according to at least one of claims 1 to 3, characterized in that the purity of the magnesium hydroxide is at least 90%, has a coating, preferably produced by grinding in the presence of free fatty acid, contains 1 to 4 wt .-% calcium carbonate and / or the BET value is at least 5 m ² / g.

5. Wrapping film according to at least one of the preceding claims, characterized in that the magnesium hydroxide is brucite.

6. Wrapping film according to at least one of the preceding claims, characterized in that the magnesium hydroxide content is 70 to 200 phr, preferably 110 to 150 phr.

7. Wrapping film according to at least one of the preceding claims, characterized in that the magnesium hydroxide content is chosen so high that the oxygen index (LOI) is above 20, preferably above 23 and in particular above 27%, or the fire speed according to MVSS 302 is below 200, preferably below 100 mm / min.

8. Wrapping film according to at least one of the preceding claims, characterized in that the wrapping film on one or both sides, preferably on one side, a pressure-sensitive adhesive layer, which is preferably based on polyisoprene, ethylene vinyl acetate copolymer and / or polyacrylate, and optionally a primer layer between the film and the adhesive layer, the amount of the adhesive layer in each case 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 unwinding 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 polyolefin has a flexural modulus of less than 900 MPa, preferably as 500 MPa or less and in particular 80 MPa or less.

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

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

13. Wrapping film according to at least 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.

14. Wrapping film according to at least one of the preceding claims, characterized in that the wrapping film has a thermal stability of at least 105 ° C, preferably 125 ° C after 2000 and in particular after 3000 hours, the wrapping film has an elongation at break of at least 100% after 20 days of storage at 136 ° C, the wrapping film is compatible when stored on a cable with a polyolefin insulation of at least 105 ° C after 3000 hours, the wrapping film 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 wrapping film contains a combination of sterically hindered phenols with a molecular weight of more than 500 g / mol (especially> 700 g / mol) with a phosphitic secondary antioxidant (especially with a molecular weight> 600 g / mol) ) contains, the wrapping film a combination of low volatile primary phenolic n antioxidant and in each case a secondary antioxidant from the classes of the sulfur compounds (preferably with a molecular weight of more than 400 g / mol, in particular> 500 g / mol) and the phosphites, the wrapping film is compatible with storage on a cable with a Polyolefin insulation of 125 ° C after 2000 hours, preferably after 3000 hours or of 140 ° C after 168 hours and / or a heat resistance of 170 ° C (30 min).

15. Wrapping film according to at least one of the preceding claims, characterized in that the wrapping film is free of plasticizers or the plasticizer content is so low that the fogging value is above 90%.

16. A method for producing a wrapping film according to at least one of the preceding claims, characterized in that the compounding takes place in a kneader or extruder in such a way that the Compound-made wrapping film has a breakdown voltage of at least 3 kV / 100 μm, preferably at least 5 kV / 100 μm, the flame-retardant filler is not added at once in the production of the compound, but at least in two portions and / or 5 the compound without one Intermediate stage in solid form of the film production is melted by extrusion or calendering.

17. A method for producing a wrapping film according to at least one of the preceding claims, characterized in that the production by 0 calendar processing, wherein the melt index of the polypropylene copolymer is less than 5 g / 10 min, preferably less than 1 g / 10 min and in particular less than 0.7 g / 10 min, and / or extrusion processing, the melt index of the polypropylene copolymer being between 1 and 20 g / 10 min, in particular between 5 and 15 g / 10 min. 5

18. A method for producing a wrapping film according to at least one of the preceding claims, wherein • the wrapping film is wound into bars, which are then annealed to increase the unrolling force and then cut into rolls, the unrolling force of the material thus produced at 300 mm / min is preferably at least 50% higher than without such a measure, • the wrapping film is subjected to a flame or corona treatment to increase the unwinding force or is provided with a polar coextrusion layer and then processed into rolls, the unwinding force of the material thus produced being 300 mm / min is preferably at least 50% higher than without such a measure, • the wrapping film is cut by a method which leads to easier tearing by rough cut edges, the elongation at break of the wrapping film rolls cut in this way preferably being at least 30% lower than in the case of Cut with sharp blades, • the wrapping film is cut by a process which, due to rough cut edges, makes it easier to tear by hand, the elongation at break of the wrapping film rolls cut in this way preferably being in the range from 200 to 500%, • The wrapping film is cut on an automatic parting machine at a defined knife feed speed and / or • The wrapping film is wound on a core with an inner diameter of 30 to 40 mm, preferably made of cardboard.

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