Use of copolymer of alpha-olefins and unsaturated nonpolar comonomer as surface protecting sheet.

The present invention relates to the use of a copolymer of α-olefins and from 5 to 80 wt .-%, based on the copolymer, of unsaturated, polar comonomers as an adhesive surface protective film in the transport of automobiles.

After today's practice newly produced automobiles after completion of painting are equipped with transportation protection, which ensures that damage to the vehicle paint by scratches or by environmental influences such as rain, snow or dirt can be ruled out during transport from producer to retailer. At present this transport protection of various waxes which are applied to the paint of the car after completion of the paintwork. Upon receipt of the automobile by the traders it must remove the wax layer by a relatively expensive dewaxing again. The solvent used in this case represent a considerable disposal problem for the retailer beyond.

For some time, there is the possibility to carry out the dewaxing of the automobile in the so-called Entwachsungszentren where the disposal of the resulting solvent and the wax residue can be carried out more favorable to the automobile dealers. However, the removal of the wax layer in such Entwachsungszentren connected for the trader with a financial and time penalty, since he must pay for the transport to Entwachsungszentrum and back as well as the costs incurred. In addition, also fall in this way to substantial amounts of solvents and wax residue that must be disposed of and thus also contribute to environmental pollution.

From the patent application DE-P 4223822.6 is known to solve this problem by the merchants that use an adhesive surface protective film during transport from producer, which can be easily removed from the merchants and can be supplied as an unmixed plastic targeted recycling. By using an adhesive surface protection film the disposal of residual wax or solvent waste is eliminated. As adhesive surface protection films doing the usual in art films are used, which can be applied to a body.

The adhesive from DE-P 4223822.6 known surface protection films can be generally relatively easy to remove from the body of the automobile, but often leave an adhesive edge on the body, which still has to be removed. In addition to occasionally observed at very high temperatures of over 70 ° C irregularities and distortions in the area covered by the adhesive surface protective films paint surfaces.

The present invention was therefore based on the object to overcome these drawbacks and to develop a surface protective film which has over the surface protective film known from DE-P 4223822.6 still improved properties.

This object has been achieved by the use of a copolymer of α-olefins and from 5 to 80 wt .-%, based on the copolymer, of unsaturated, polar comonomers as an adhesive surface protective film in the transport of automobiles. This surface protection film takes on the protective function of the wax during transport of the automobile from producer to retailer.

The adhesive surface protection film used for this purpose is on the one hand on the resist layer of the automobile even at elevated mechanical loads such as strong air currents during transport on trucks or rail cars still adhere well and at the same time on the other hand as a protective layer against mechanical damage and environmental influences such as rain, snow, serve hail or debris.

Preferably, such an adhesive surface protective film is used which consists of a copolymer of α-olefins and from 10 to 60 wt .-%, based on the copolymer contains in unsaturated, polar comonomers.

The term α-olefins are in particular C₂- to C₁₀ α-olefins such as ethylene, propylene, but-1-ene, pent-1-ene, hex-1-ene, hept-1-ene or oct-1 -en be understood, with preferably copolymers of ethylene, propylene and 1-butene are used. The term α-olefins shall also comprise isobutylene. The α-olefins may either individually or as mixtures are used together in the invention to be used copolymer together with the unsaturated polar comonomers. α-olefins which can be used especially well as mixtures, are, in particular ethylene, propylene and 1-butene.

The term unsaturated, polar comonomers in this context means especially comonomers such as vinyl acetate, vinyl chloride, acrylonitrile, and unsaturated carboxylic acids, for example maleic acid, fumaric acid, acrylic acid, methacrylic acid, or glutaric acid. Suitable unsaturated, polar comonomers and the corresponding anhydrides, esters, amides, imides and acid halides of these acids may be used here.

For the inventive use in particular copolymers of ethylene are from 15 to 60 wt .-%, preferably 30 to 50 wt .-% of vinyl acetate as a comonomer. Copolymers of ethylene and vinyl acetate are available, for example under the tradename Lupolen V® by BASF Aktiengesellschaft.

The copolymers of α-olefins and unsaturated, polar comonomers is carried out with the customary in the art of copolymerization, for example by Hochdruckcopolymerisation using free radical initiators, by copolymerization with Ziegler or Ziegler-Natta catalysts or Phillips catalysts, or by copolymerization with metallocene catalysts. The copolymerization can be performed while in the gas phase, in solution or in a suspension either continuously or discontinuously. Such preparation processes are known to the people working in the plastics technology specialist.

Suitable for use in the invention copolymers can furthermore contain conventional fillers such as talc, barite or kaolin and common additives such as antioxidants or UV stabilizers, such as soot, contained.

For such copolymers, the respective films may, inter alia, in calenders or extruders after blowing or flat film process at a temperature of 170 to 240 ° C, a pressure of 250 to 400 bar and an average lead time of 5 to 20 minutes. getting produced. Other conventional methods for preparing the adhesive surface protective film include the coating process and the lamination process.

In the coating method, for example, the coating composition to be used is first applied to a carrier sheet, then the operations gelling, cooling, peeling and winding are carried out. In the actual co-extrusion coating, in a coating installation with a melt film that is melted in an extruder and discharged through a slit die and may consist of one or more polymeric layers coated. The resulting composite is then cooled and smoothed in a cold-pressing rolls unit. After the winding of the composite web is carried out in an appropriate winding station.

When laminating the operations applying the coating composition to be performed on the carrier sheet, smoothing and cooling, peeling and winding similar to the coating process also. In the actual extrusion lamination can be a prefabricated carrier sheet in a Glättwerkwalzenstuhl having 4 rolls shrink. The carrier web with a melt film that is melted in an extruder and discharged through a sheet die, coated before the first roller gap. Before the second nip is allowed to run a second preform strip. The resulting overall composite is smoothed on passing through the second nip, then cooled, stripped off and wound up in a winding station.

After the blowing / slot extrusion process, various polymers are generally first of all melted in different extruders under suitable conditions and subsequently combined in the form of melt streams with formation of a multilayer melt stream in the extrusion tool. After the discharge, peeling and cooling of the multilayer melt sheet and winding the composite is. In this way, a composite film. The slit-extrusion process is in this case applied preferably.

Such methods are, at temperatures of 170 to 300 ° C, pressures of 250 to 400 bar and with average throughput times 5-20 min usually carried out. Since the copolymers in the melt and in the film have a high tendency to stick to all contact surfaces, the rollers used for the production of the composites as well as the take-off rollers are coated with a respect to the copolymers antiadhesive material, for example, with polytetrafluoroethylene. This allows, among other things to use appropriate web tension for the proper winding of the composites.

The thus obtainable adhesive surface protection films can be used according to the invention for transporting automobiles. The application of the adhesive surface protective film on the resist layer of the automobile can be effected both manually by lightly pressing on the film, as well as by use of rotating film rolls which are moved like the commonly used in car washes rolls slowly over the automobile. Then may optionally be fused briefly by thermal treatment, the film, to thereby obtain a complete, all surface roughnesses covering protective layer. The underside of the automobile remains free as well as the area of ​​the wheels of the surface protective film. Furthermore, the vertical side surfaces of the automobile, for example, in the side door area, are spared from the adhesive surface protective film completely or at least partially. In this way, the application of the adhesive surface protective film is facilitated. Moreover, it may be advisable to leave out the area of ​​the windshield of the car of the surface protective film to allow in this way short trips of covered with the adhesive surface protective film automobile, for example, the car transporter to the dealer.

Furthermore, it is possible to provide the adhesive surface protective film in the area of ​​the driver's door of the car with an easily removable by a perforation of the remaining surface protective film area, allowing ease of entry into the automobile without major damage to the film. Such perforations are usually applied by the in-line perforation process on films. In addition, can be provided the driver's door of the car with its own adhesive surface protective film separately from other automobile.

Preferably, the adhesive surface protection film to lie directly on the body of the automobile, at least one further protective layer are applied.

The main task of on the adhering surface protection film additionally applied protective layer consists essentially, to strong environmental influences such as rain or snow to be as insensitive as possible and moreover stresses away as dirt or chemical and mechanical effects of the paint layer. As protective layers, in particular thermoplastic polymers such as polyamides, polystyrene, polyesters, polycarbonates or polyolefins can be used. Preferably, protective layers of polyolefins are used, for example, ethylene homopolymers, propylene homopolymers or propylene-ethylene copolymers. The production of such polyolefins can be done by the skilled worker of polymerization, for example by Ziegler-Natta polymerization, by polymerization with the aid of Phillips catalysts, by high pressure or by polymerization using metallocene catalysts. These polyolefins the appropriate protectors can be prepared analogously to the adhesive surface protection films and more for the blown or flat film process.

Serving as the protective film can be applied by area as similar as possible applied to the adhesive surface protective film according to their preparation. Such preparation processes for multilayer films are usually carried out after the coating process, the laminating process or the blowing / slot coextrusion. The protective layer can further contain conventional additives, for example UV stabilizers, eg carbon black or antioxidants. It may also contain fillers such as talc, kaolin or barite be used.

In accordance with the invention using the adhesive surface protective film of the transport of automobiles can be performed from producers to distributors lighter and more environmentally friendly. By the adhesion of the film to the body of the automobile, a swelling of the film is avoided when occurring wind, so that damage to the film during transport is prevented. At the dealer the adhesive surface protective film can then be removed by simply pulling the automobile without consuming removing the wax.

An after-treatment of the body of the automobile with water or chemical solvents is unnecessary as well as the disposal of residual wax or solvent waste. The adhesive surface protective film can be space-saving coiled and supplied as unmixed plastic without further separation process of a targeted recycling.

The inventive use of a copolymer of α-olefins and unsaturated, polar comonomers as an adhesive surface protection film allows, among other things, to remove the film from the body so that no adhesive edge remains on the body. Moreover, such an adhesive surface protection film can also apply at very high temperatures of more than 70 ° C, without causing unevenness or distortions in the area covered by the film coating surface occur.

In this context it is particularly important to employ such copolymers according to the use according to the invention, the content of unsaturated, polar comonomers, based on the copolymer, from 5 to 80 wt .-%, in particular 10 to 60 wt .-% is. If the content of unsaturated, polar comonomers less than 5 wt .-%, as is often observed deformations or distortions of the adhesive surface protective film, leading to influencing the paint surface. In a co-monomer content of more than 80 wt .-% often are very difficult to remove the adhesive surface protective film from the body.

The use of an adhesive surface protective film for the transport of automobiles is conceivable for all common types of vehicles. In addition to passenger cars work quite including minibuses, small trucks, campers, ATVs and utility vehicles.

Examples 1 and 2 and Comparative Example A

The following examples 1 and 2 and Comparative Example A illustrate the inventive use of the adhesive surface protective film closer.

example 1

In Example 1, a surface protection sheet was used which consists of an ethylene-vinyl acetate monofilm with 33 wt .-% of vinyl acetate and an admixed carbon black additive (2 wt .-%).

The protective films were applied by means of a pressure roller bubbles on the paint surface of several sheets with black, red, green or pink-colored paint and then melted in an oven to achieve optimum coating of the paint surface into the region of their microroughnesses.

The peel strengths of the surface protective film sheet composites were then tested at various temperatures. Moreover, the lacquer surfaces were on surface changes and adhesive deposits out visually after deduction of the films examined by an optical microscope as well as by surface infrared spectroscopy.

The consisting of the surface protective film and provided with a lacquer layer sheet composites were over a period of 7 days at -15 ° C (in cold unit), at 23 ° C and 54% relative humidity and each at the temperatures 60, 70 and 80 C. investigated (in the oven).

The test for peel strength of each sample was carried out with the aid of a tensile testing machine at a test speed of 100 mm / min and a sample size of 15 * 145 mm. The samples were therefore in the form of narrow strips. In the test, the film strips were manually peeled off over a length of 15 mm from the paint surface of the sheet. On this strip width a specially for this purpose suitable, sufficiently long tape was attached (no measurable eigenstrain within the predetermined test area).

In the next step, the sheet was vertically clamped in the clamps of the machine; wherein the portion of the sheet from which the film was withdrawn over 15 mm, was mounted directly between the lower jaws. Between the upper clamping jaws the free end of the applied tape was clamped.

With this arrangement could in the subsequently performed tensile test the foil strips, while maintaining a constant peel angle, shall be deducted from the sheets and are recorded in a displacement-force diagram of the course of the peel strength / strips.

The tensile tests were (2 for all samples under room temperature conditions performed 3 ° C, 54% relative humidity).

BEYOND these experiments was so attached to the luggage carrier of a passenger car, the above-mentioned surface protection foil sheet composites that they were subjected to when driving the forces of the slipstream and the natural environment influences. The films were deposited while analog means of a pressure roller on the sheet and then heated. The surface coated with the surface protective film sheets were fixed horizontally on the luggage carrier. The composites used in this way were then tested for 14 days at different weather and wind speeds of up to 120 km / h on their suitability.

The composites survived these tests without showing any damage. In none of the sample part, the surface protective film peeled off from the paint surface.

In the experiments carried out it was found that the surface protective films used on the paint surfaces, no mechanical damage left behind both at temperatures of -15 ° C, at 23 ° C and in the temperature range of 60 to 80 ° C, regardless of the type of resist used. In addition to the paint surfaces no surface changes or glue deposits were found.

example 2

Analogously to Example 1 were used from an ethylene homopolymer of Example 2 Co-extrusion of an adhesive layer of an ethylene-vinyl acetate copolymer with 33 wt .-% vinyl acetate and a protective layer.

The films were subjected to the same tests as in Example 1st

The results from the trial evaluations results are identical to the results of Example. 1

Comparative Example A

In Comparative Example A, however protective films were used, which consisted of an adhesive layer of a natural crosslinked rubber adhesive and thereon a protective layer of an ethylene homopolymer.

In contrast to Examples 1 and 2, these films have not been melted in a heating furnace, so as the structure of the adhesive layer would have been impacted.

These films were prepared as described in Example 1, subjected to various proficiency tests.

In contrast to the results of the inventive examples 1 and 2 remained after stripping of the films on the paint surface adhesive edges left that required reworking and therefore a further operation.

Further, in the film strip a larger and more uneven warpage was found. This due to partial detachment of the films resulting from the paint surface, thereby providing a comprehensive surface protection of coatings can not be fully guaranteed.