DE9309206U1 - Thermoformable composite film - Google Patents

Description

Thermoformable composite film Description

The present invention relates to a thermoformable composite film, which contains a polyolefin-containing upper film and at least one polyolefin-containing lower film that differs qualitatively and/or quantitatively from the composition of the upper film, and optionally a surface protection layer, wherein the upper film contains certain amounts by weight of a) a cross-linked PP-EPDM and b) an uncross-linked propylene block copolymer or heterophasic propylene block polymer, wherein b) is partially replaced by a polymer and/or ionomer containing reactive groups c).

The base film contains partially cross-linked EPDM polypropylene and polymers containing reactive groups and/or ionomers and/or polymeric cross-linking agents.

A wide variety of films based on polyolefins, in particular those based on polypropylene with polyethylene and their processing are already known (see FR-A-2017705, among others). However, the requirements for the films depending on the area of application are so different and are associated with increasing demands that there is a need for films with improved and/or improved processing options.

In the context of this invention, numerous tests were carried out with film formulations, in which, among other things, those containing a cross-linked PP-EPDM and an uncross-linked propylene block copolymer or heterophasic propylene block polymer were tested. These films have good grain stability and have a certain degree of matting or a certain mattness, as is desired in several areas of application (e.g. car interior trim and the like).

However, the film of this composition has the disadvantage that it is difficult to deep-draw, as the grain stability is partially lost. It follows that the deep-drawability of the film needs to be improved.

The methods known to date for matting flexible PP-EP or PP-EPDM compositions with mineral fillers, e.g. talcum, result in an increase in rigidity and a deterioration in aging behavior. In addition, the matting effect is strongly influenced by the degree of deformation. The use of elastomer particles in rubber mixtures (see EP-B-0257242, among others) is also unsuitable.

Other options for matting plastic film surfaces with matt varnishes are not suitable for producing thermoforming films or do not produce uniform structures with matt effects after embossing.

Special requirements are placed on plastic films for the production of deep-drawable automotive films, sheets or automotive film layers, since the molded parts have to comply with different deep-drawing ratios on the same molded part. Nevertheless, the molded part should have the same embossed structure and mattness in all places. On the other hand, special requirements are placed on the scratch resistance of the plastic surfaces, fog values, aging stability and the like.

The aim and object of the present invention was to achieve an improved film with improved properties or processing properties compared to the prior art. In particular, the film should have good grain stability, the surfaces should be matt without additional matting agents or have a certain mattness or degree of matting. In particular, however, the film should be easy to deep-draw and also be able to be processed into molded parts or objects that have relatively high requirements.

Such areas of application include, for example, molded parts, objects or deep-drawn parts for motor vehicles, in particular motor vehicle interior trim.

According to the invention, it was found that these aims and tasks are met by a thermoformable composite film that contains a polyolefin-containing upper film and at least one polyolefin-containing lower film that differs qualitatively and/or quantitatively from the composition of the upper film, and optionally a surface protection layer. According to the invention, the upper film contains (based on 100 parts by weight of plastic in the upper film)

a) 20 to 80 parts by weight

at least one cross-linked PP-EPDM (alloy or mixture of propylene homopolymer and/or copolymer and cross-linked or partially cross-linked ethylene-propylene-diene copolymer)

b) 80 to 20 parts by weight

an uncrosslinked propylene block copolymer or heterophasic propylene block polymer, with an elastomer content in the block or in the chain of 35 to 75% by weight (based on 100 parts by weight of the uncrosslinked heterophasic propylene block copolymer or propylene block polymer), where b is replaced by 15 to 1% by weight, preferably 10 to 2% by weight, by the same amounts by weight of a polymer and/or ionomer c containing reactive groups, where

c) at least one polymer and/or ionomer containing reactive groups based on ethylene and methacrylic acid and/or acrylic acid, the acid groups partially containing metal ions or being neutralized by metal ions,

Y Y» Y

and the bottom film or bottom films (based on 100 parts by weight of plastic of the bottom film or bottom films) consists of

d) 1 to 60 wt.%, preferably

5 to 55 wt.%

at least one partially cross-linked EPDM

e) 12 to 30 wt.%, preferably

13 to 25 wt.%

Propylene homopolymer, copolymer or graft polymer with or without reactive groups

f) 77 to 9.5 wt.%, preferably

73 to 19 wt.%

at least one polymer and/or ionomer containing reactive groups based on ethylene and methacrylic acid or acrylic acid, wherein the acid groups partially contain metal ions or are neutralized by metal ions and

g) 10 to 0.5 wt.%, preferably

9 to 1 wt.%

at least one polymeric crosslinking agent containing reactive groups, which contains more than 51% by weight (based on 100 parts by weight g) ethylene or other olefin groups and 1 to 49% by weight acrylate and/or methacrylate groups and reactive groups, where reactive groups are epoxy, isocyanate, ketone, aldehyde, silane, alkyl halide and/or anhydride groups.

Although the thermoforming ability of the upper film needs improvement and the lower film does not have good grain stability, the combination of upper and lower film(s) surprisingly results in very good embossability, grain stability and very good thermoforming ability in the composite film.

The composite film according to the invention is a flexible, deep-drawable motor vehicle film or sheet that is particularly well suited for the production of thermoformed molded parts with a uniformly matt surface for motor vehicle films for interior trim. The mattness of this film is largely independent of the deformation temperature and the degree of deformation, i.e. the film surface or the thermoformed molded part produced from it has the same or almost the same mattness at all points on the molded part.

The top film preferably contains a dynamically cross-linked or partially cross-linked PP-EPDM or PP-EPDM mixtures or alloys. The components a), b) and c) of the top film are optionally used in combination with processing aids, additives, fillers, dyes and/or color pigments.

The polypropylene block of the non-crosslinked heterophasic polypropylene block polymer preferably consists of a propylene, co- and/or block polymer. The elastomer content of the heterophasic polypropylene block copolymer is, according to a preferred embodiment, 40 to 70% by weight (based on 100 parts by weight of the non-crosslinked heterophasic propylene block copolymer).

According to a preferred embodiment, the elastomer of the ethylene-propylene copolymer has a styrene content of 20 to 70% by weight, preferably 30 to 60% by weight, and a propylene content of 80 to 30% by weight, preferably 70 to 40% by weight, and has a molecular weight of greater than 100,000, preferably greater than 150,000.

The addition of a dynamically cross-linked PP-EPDM blend in the top and/or bottom film with a particle size of the cross-linked elastomer phase of 0.5 to 15 pm improves the deformation range, the uniformity of the thermal expansion and the grain pattern.

An improved grain pattern means that the disproportionate expansion of the grain valleys is limited by the increasing strength with increasing expansion (strain hardening). To achieve this effect, the cross-linked PP-EPDM blends must be incorporated homogeneously and a particle-shaped elastomer structure must be formed. This results in certain requirements for the degree of cross-linking and the melt index of the cross-linked PP-EPDM blends used. The degree of cross-linking in the complex systems, indirectly defined by the compression set at 70 ⁰ C after 22 hours (DIN 53517), should be between 25 and 60.

As heterophasic propylene block polymer, a block polymer with an Mfi 230/2.16 g/10 min of 0.3 to 8, preferably 0.5 to 7, is preferably used.

PP-EPDM, preferably dynamically cross-linked or partially cross-linked PP-EPDM, for the upper and/or lower film(s) are preferably those with a density between 0.78 and 0.96 g/cm ³ , preferably 0.83 to 0.93 g/cm ³ . The PP-EPDM that is selected for this purpose preferably has a flexural modulus (initial flexural modulus) - measured according to ASTM D 790 with a 2 mm thick film web - of 80 to 400 MPa, preferably 100 to 300 MPa.

The thermoformable composite films according to the invention have a gloss level of 0.5 to 5 on the top film according to DIN 57530/60°, which is not significantly influenced by the required forming temperature or the thermoforming ratio. This feature therefore distinguishes the films according to the invention from the knowledge gained from previous experience with films that have been mattified by fillers or embossing.

By using the additive or mixture according to the invention to produce deep-drawable automotive films, it is possible to obtain plastic films with a matt surface and high elasticity for thermoforming. The thermoforming of the composite film according to the invention can be carried out in a wide temperature range of approx. 140 to 200 ^° C, preferably 150 to 185 ^° C, without any particular difficulties occurring. The film has excellent deep-drawing properties and can be used in both the positive deep-drawing process and the negative deep-drawing process. By using the composition, it is possible to obtain deep-drawing films with a Shore D hardness of 25 to 60, preferably 30 to 55, and a gloss level according to Gardner 60 ^° C of 0.5 to 1.5, measured on the deep-drawn molded part.

The automotive composite film webs for interior trim according to the invention also have the advantage of high aging stability against light and heat as well as low fog values.

According to a preferred embodiment, the upper and/or lower film has a filler content of 0 to 30 parts by weight, 0 to 20 parts by weight (based on 100 parts by weight of plastic). The fillers used can be the fillers known per se, preferably talc and/or SiO ₂ with an average particle size of 0.01 to 20 μιη, preferably 0.05 to 10 μιη.

Heat and/or light stabilizers for polyolefins are preferably used as processing aids.

Other processing aids or additives used include lubricants or lubricant mixtures.

According to one embodiment, an adhesion promoter layer is preferably arranged below the polishing layer. The adhesion promoter layer preferably consists of acrylates, polyurethane or acrylate-polyurethane mixtures or contains these. A foam layer, a carrier layer, a fabric layer and/or support layer is preferably arranged below the film layer or adhesion promoter layer. The foam layer preferably contains a polyolefin foam or a polyurethane foam or consists thereof.

The upper film preferably has an average thickness of 60 to 500 μm, preferably 100 to 350 μm. The lower film or films have an average thickness of 100 to 2000 μm, preferably 500 to 1500 μm, the lower film or films having a total thickness that is more than 1.5 times, preferably 2 or more times, the upper film.

The composite film according to the invention is very thermoformable and is used to produce low-stress molded parts with precise reproduction of dimensionally or temperature-stable surface structures. The composite film is preferably processed or worked using the positive deep-drawing process and/or the negative deep-drawing process. The composite material preferably has a foam layer on the underside or lower surface, e.g. polyurethane foam, but preferably polyolefin foam and/or is provided with a carrier layer or a carrier and/or a support layer and/or a mesh or fabric layer. According to a preferred embodiment, the film or layer is provided with decorations, grains, embossings and the like, is grain-resistant, easy to handle and can be printed. Using the composite film according to the invention, it is possible to produce molded parts or objects whose surface has good grain stability even when stored in heat.

The objects, molded bodies, parts and the like produced or deep-drawn therefrom, which preferably contain a foam layer, carrier layer or a carrier, support layer and/or a mesh or fabric layer, are preferably used for control panels or dashboards for motor vehicles, side wall parts for motor vehicles, door panels for motor vehicles, roof interior panels (car roof liner), interior rear wall parts for motor vehicles (hat shelf) and other interior panel parts or objects for motor vehicles. According to a preferred embodiment, the carrier layer and/or foam layer contains polyolefin or is based on polyolefins.

According to a preferred embodiment, the polymeric crosslinking agent g) of the lower film or films containing reactive groups comprises, in addition to acrylate and/or methacrylate groups or acrylic acid and/or methacrylic acid groups and more than 51% by weight of ethylene and/or olefin or (CH ₂ ) or CH groups, epoxy groups or epoxy-like groups, preferably glycidyl groups.

The polymers and/or ionomers (g) containing reactive groups of the lower film preferably contain alkali and/or alkaline earth ions and/or zinc ions as metal ions.

According to one embodiment, the polymers and/or ionomers containing reactive groups (g) contain alkyl acrylates and/or alkyl methacrylates having 1 to 8 C atoms.

The composite film according to the invention is used alone or in combination with a foam layer, carrier layer or a carrier, support layer, spacer layer or a grid or fabric layer in particular for the production of motor vehicle interior panels, preferably for control panels or dashboards for motor vehicles, side wall parts for motor vehicles, door panels for motor vehicles, roof interior panels (car roof), interior rear wall parts for motor vehicles (hat shelf) and other interior panel parts or objects for motor vehicles.

1 2 80 - - 60 10 10 10

Example top film

PP block polymer

2 PP block polymer

PP-EPDM

4 PP-EPDM

Ionomers 10 -

6
Ionomers - 10

Example bottom film 1 2

PP block polymer 30

PP-MA - 30

EPDM40

EPDM- ⁸ - 30

Ionomers 27

Ionomers - 35

Ethylene glycidyl methacrylate 3 5

(1) MFI = 0.8 230 °C/21.6 N

(2) MFI = 3.0 230 °C/21.6 N

(3) MFI = 5.0 230 °C/21.6 N

(4) MFI = 30.0 230 °C/21.6 N

(5) Cation type Zinc MFI 1.0 190 °C/21.6 N

(6) Cation type Zinc MFI 3.0 190 °C/21.6 N

(7) Mooney viscosity ML 1+4 121 ⁰ C = 40

(8) Mooney viscosity ML 1+4 121 ⁰ C = 48

(9) Acrylic acid content 6 %

Drawing description

In the attached drawings (Figures 1 and 2) some embodiments of the composite film according to the invention are shown schematically, wherein the thickness dimensions do not correspond to the actual thicknesses of the layers (in particular in the case of the surface protection layer or lacquer layer, which in practice is between 8 and 60 µm, preferably 10 to 50 µm).

(1) shows the lacquer or surface protection layer, which is preferably applied in the form of a bonding agent or solvent such as synthetic resin for the surface coating.

The bottom film(s) (3) is/are arranged under the top film (2). In Figure 2, a further layer (4) is also shown schematically, which is a foam layer and/or carrier layer.

Claims (10)

Protection claims Thermoformable composite film which contains a polyolefin-containing upper film and at least one polyolefin-containing lower film which differs qualitatively and/or quantitatively from the composition of the upper film and optionally a surface protection layer, characterized in that the upper film (based on 100 parts by weight of plastic of the upper film) 20 to 80 parts by weight at least one cross-linked PP-EPDM (alloy or mixture of propylene homopolymer and/or copolymer and cross-linked^ or partially cross-linked ethylene-propylene-diene copolymer) 80 to 20 parts by weight of an uncrosslinked propylene block copolymer or heterophasic propylene block polymer, with an elastomer content in the block or in the chain of 35 to 75 wt.% (based on 100 parts by weight of the uncrosslinked heterophasic propylene block copolymer or propylene block polymer), wherein b is replaced by 15 to 1 wt.%, preferably 10 to 2 wt.%, by the same weight amounts of a polymer and/or ionomer c containing reactive groups, wherein c) at least one polymer and/or ionomer containing reactive groups based on ethylene and methacrylic acid and/or acrylic acid, the acid groups partially containing metal ions or being neutralized by metal ions, and the bottom film or bottom films (based on 100 parts by weight of plastic of the bottom film or bottom films) made of d) 1 to 60 wt.%, preferably 5 to 55 wt.% at least one partially cross-linked EPDM e) 12 to 30 wt.%, preferably 13 to 25 wt.% Propylene homopolymer, copolymer or graft polymer with or without reactive groups f) 77 to 9.5 wt.%, preferably 73 to 19 wt.% at least one polymer and/or ionomer containing reactive groups based on ethylene and methacrylic acid or acrylic acid, wherein the acid groups partially contain metal ions or are neutralized by metal ions and g) 10 to 0.5 wt.%, preferably 9 to 1 wt.% at least one polymeric crosslinking agent containing reactive groups, which contains more than 51% by weight (based on 100 parts by weight g) ethylene or other olefin groups and 1 to 49% by weight acrylate and/or methacrylate groups and reactive groups, where epoxy, isocyanate, ketone, aldehyde, silane, alkyl halide and/or anhydride groups are considered reactive groups. 2. Thermoformable composite film according to claim 1, characterized in that in the upper film polypropylene block of the non-crosslinked heterophasic polypropylene block polymer from • #· · · · • * ·· ·· * · ·
· · •
· * • • · * &igr; · · • · * · · · ·· ·· ···· a propylene homo-, co- and/or block polymer and the elastostomer content of the heterophasic polypropylene block copolymer is 40 to 70 parts by weight {based on 100 parts by weight of the uncrosslinked heterophasic propylene block copolymer). 3. Thermoformable composite film according to claims 1 and 2, characterized in that the elastomer of the ethylene-propylene copolymer has an ethylene content of 20 to 70 wt.%, preferably
30 to 60 wt.%, and a propylene content of 80 to 30 wt.%/ preferably
70 to 40 wt.%, and has a molecular weight greater than 100,000. 4. Thermoformable composite film according to one or more of claims 1 to 3, characterized in that the heterophasic propylene block polymer has an Mfi 230/2.16 g/10 min 0.3 to 8, preferably
0.5 to 7, owns. 5. Thermoformable composite film according to one or more of claims 1 to 4, characterized in that the PP-EPDM, preferably dynamically crosslinked or partially crosslinked PP-EPDM, with a density between 0.78 to 0.96 g/cm ³ , preferably 0.83 to 0.93 g/cm ³ , are contained in the upper and/or lower film. 6. Thermoformable composite film according to one or more of claims 1 to 5, characterized in that the PP-EPDM for the bottom and/or top film has a flexural modulus (initial flexural modulus) measured according to ASTM D 790 with a 2 mm thick film web - of 80 to 400 MPa, preferably 100 to 300 MPA. 7. Thermoformable composite film according to one or more of claims 1 to 6, characterized in that the polymeric crosslinking agent g) containing reactive groups of the lower film or lower films has, in addition to acrylate and/or methacrylate groups or acrylic acid and/or methacrylic acid groups and more than 51% by weight of ethylene and/or olefin or (CH ₂ ) or CH groups, epoxy groups or epoxy-like groups, preferably glycidyl groups. 8. Thermoformable composite film according to one or more of claims 1 to 7, characterized in that the polymers and/or ionomers (g) of the lower film containing reactive groups contain alkali and/or alkaline earth ions and/or zinc ions as metal ions. 9. Thermoformable composite film according to one or more of claims 1 to 8, characterized in that the polymers and/or ionomers containing reactive groups (g) contain alkyl acrylates and/or alkyl methacrylates with 1 to 8 C atoms. 10. Thermoformable composite film according to one or more of claims 1 to 9, characterized in that the upper film has an average thickness of 60 to 500 pm, preferably
100 to 350 μπα. and the bottom film or films have an average total thickness of 100 to 2500 μηη, preferably
500 to 1500 μια, wherein the thickness of the bottom film or films is more than 1.5 times, preferably 2 or more times, the thickness of the top film.