DE29615956U1 - Multi-layer decorative film made of plastic lacquer film, almost like a stiff cloth - Google Patents

Description

Multilayered decorative foil made of plastic, almost like a stiff cloth - "lacquer foil"

The invention relates to an at least 2-layer, preferably laminated, almost like a stiff cloth, supple, opaque, colored, high-gloss decorative film with an optional first outer layer made of preferably polypropylene, oriented polyester of the smallest thickness, alternatively an outer layer made of polyamide 12 and a further second layer of a very soft, supple, low-density polyethylene. The thickness of all layers of the film is less than 100 my. The high-gloss outer layer of the film achieves a gloss of at least 90 measured according to ASTM-D2457 and therefore enables the use of the decorative film as a "lacquer film". The new decorative film is thinner than a soft PVC film, almost as stiff as a starched cloth, free of chlorine, remains smooth and optionally contains no plasticizers; the heat resistance is higher than that of soft PVC films. The properties of the new decorative film enable the substitution of soft PVC films, which are used as decorative films for tablecloths, for example, with or without a printed decoration such as a "lacquer film". All layers of the film are inseparably connected to one another by adhesive lamination or CO extrusion.

Description

The "lacquer films" currently used are opaque colored decorative films made of 150 my to 200 my thick soft PVC, which have a high-gloss surface on at least one side and are used for decorative purposes; e.g. as tablecloths in the catering sector or as decorative film for covering panels and walls. The films made of soft PVC only achieve their soft character by adding a very high proportion of plasticizers. Despite the change in dimensions, they are extremely popular for a large number of applications.

The invention relates to a multilayer film with an outer high-gloss surface of the layer (1) made of preferably polypropylene or CO-polypropylene, alternatively a polyamide type 12, which is connected to an opaque colored layer (3) made of a low-density polyethylene to form a 3-layer film by a layer (2) of an adhesion promoter using the CO-extrusion process or an adhesive using the lamination process. Figure 1 shows such a film. Alternatively, the layer (1) can consist of an oriented thermally fixed polyester, the thickness of which is a maximum of 4 my to 6 my due to the desired low rigidity. The opaque colored layer (3) made of low-density polyethylene can contain up to 70% by weight of pigments; the specific weight of polyethylene thus increases from 0.92 to up to 1.9. The polyethylene filled with such a high proportion of pigments reduces the stiffness and allows this film to fall out of layers (1), (2) and (3) like a cloth; this is one of the essential characteristics of the film.

The dimensional stability of the new film outdoors is an essential feature. With soft PVC, this is easily lost; this happens through the absorption of moisture, migration of the plasticizer or exposure to heat. Exposure to sunlight causes the film to soften and change dimensions; the absorption of moisture or water by the soft PVC film causes the film to swell; the change in dimension is detrimental to the formation of waves in the soft PVC film used as a "tablecloth". Materials are used for the new decorative film that either have no or very little absorption of moisture and, if possible, no plasticizers, and whose heat stability is significantly higher than that of soft PVC. The new film remains smooth and does not form waves even outdoors or in high humidity or when used directly in water. This property is an essential feature and favors the use of the film.

The film can be produced by laminating two finished films or by CO extrusion of all layers in one operation. The lamination process requires a greater thickness of the prefabricated film of layer (1) than the layer (1) produced by CO extrusion. Lamination of two finished films is advantageous if a layer (1) consists of an oriented thermally fixed polyester, a polypropylene or a CO polypropylene with lower rigidity or a film made of polyamide 12 and optionally a printed decorative film with the printing ink between the layers is desired. The polypropylene or CO polypropylene can also be a biaxially oriented thermally fixed layer (1). The CO extrusion process enables the production of an outer very thin layer (1) with a thickness of 3 my to 15 my, preferably 5-9 my. This outer thin layer (1) reduces the stiffness of the glossy soft multilayer film made of layers (1), (2) and (3) with the possibility of substituting soft PVC with the multilayer film.

The preferred method of producing the new film is the known method of lamination using 1- or 2-component adhesives from at least 2 films of layers (1) and (3). By means of adhesive lamination, it is possible to produce a multi-layer film with a low tendency to curl; the tensions of the individual layers when joining the films can be almost balanced out, so that the tendency to curl of the films is only slight or falls to a negligible residual value. With the film produced using the co-coextrusion process, the effect of low curling can hardly or not at all be achieved; the film always has a strong tendency to curl due to the fixed, very different thermal reaction points and shrinkage values of the individual plastics. A film with the property of a strong tendency to curl can only be used partially for decorative purposes, but not as a film with the alternative use of a cloth, a decorative paper or to replace the soft PVC film.

The outer high-gloss layer (1) can be made of

♦ Homo-polypropylene with a thickness of 12 my up to a maximum of 30 my and achieves a surface gloss of 95 in a water-cooled film as measured according to ASTM-D2457. These films are available as biaxially oriented thermally set water-cooled films and are the preferred material for layer (1).

The moisture absorption of polypropylene is minimal; the material does not swell due to absorption of moisture.

♦ An oriented, thermally fixed polyester with a thickness of 5 to 6 my can also be used for layer (1). The very hard plastic polyester does increase the stiffness of the film, but a layer (1) made of polyester with a thickness of 5 my to 6 my combined with a soft layer (3) produces a still usable, almost soft film. Polyester absorbs very little moisture; the material does not swell due to the absorption of moisture.

♦ An alternative material that can be used for the outer layer (1) is polyamide type 12. This film without any plasticizers is made from polyamide 12 from UBE Industries Ltd.

Tokyo Japan, here type 3035 C2, was produced by the CO extrusion process using a ring nozzle and cooling using room air with the required high gloss of a "lacquer film" with a value of 90 according to ASTM-D2457 at 45° film.

It is known that when producing a blown film using cooled air, the faster cooling results in a higher surface gloss and thus a value of 95 and higher can be achieved. In addition, instead of using a ring nozzle, the film can also be produced by pouring the plastic from a flat nozzle against a cooled roller, the chill-roll process. This means that a higher surface gloss can be expected than with a ring nozzle process.

Polyamide 12 is a homopolymer of laurolactam, generally referred to as polylaurolactam, and is produced by ring-opening polymerization of a lactam. Optionally, plasticizers can be added to improve flexibility if the stiffness of layer (1) is too high and the soft character of the film is lost as a result. The other types of polyamide, such as polyamide 6, polyamide 610, polyamide 66, polyamide 11 and CO-polyamides made from them, are usable but not recommended either because of their greater absorption of water until it is saturated or because of their lower surface gloss and the fact that the polyamide 610 type of layer (1) is not approved for direct contact with food. The layer (1) made of polyamide 12 is characterized by higher quality properties than those of soft PVC. These are:

♦ The lower value of 1.4% of water absorption at 23° C to saturation,

♦ higher abrasion resistance and therefore higher surface hardness,

♦ weather resistance,

♦ excellent impact strength even at low temperatures and the possibility of

♦ to achieve a very soft slide (1) by adding plasticizers.

Decorative films made of SOFT PVC, when used as "lacquer films", require a very high gloss; films with a gloss value of 80 or less measured according to ASTM-D2457, meet the quality requirements of a decorative film, but not those of a decorative film used as a "lacquer film". If the gloss value of a "lacquer film" falls below the value of 80 measured according to ASTM-D2457, the film can no longer be used as a lacquer film; the required gloss is too low or no longer present. With the described material of a polyamide 12 from UBE Industries, the surface gloss of a film produced as a blown film could be achieved or exceeded as an alternative to the well-known "lacquer film ¹¹ " made of soft PVC.

Alternatively, the thin layer (1) made of polypropylene or polyamide 12 can be formed by the CO extrusion process with the layers (2) and (3). The film then has a tendency to curl, which is disadvantageous for many applications. The process of pouring the plastic against a cooled roller, the chill roll process, results in a surface gloss of 95 for homo-polypropylene and 90 for CO-polypropylene according to ASTM-D2457. The layer (1) made of polypropylene, in particular non-oriented polypropylene, results in a short-lived decorative film.

The layers (2) of the laminating adhesive or the extrudable adhesion promoter and the layer (3) of the polyethylene absorb almost no water.

When producing the laminated film, layer (2) of the laminating adhesive must be made using a 2-component adhesive with a reduced proportion of hardeners than is otherwise recommended. This makes the film softer. The recommended ratio of the mixture of a 2-component adhesive from Herberts GmbH Wuppertal, type EPS 71 and hardener KN 75, is 100 parts by weight of the polyurethane-based adhesive, to which 8 parts by weight of a hardener are added. If the proportion of hardener is less than 8 parts by weight, the stiffness of the film consisting of layers (1), (2) and (3 is reduced, so that the soft film similar to a cloth is achieved. The reduced proportion of hardener in the laminating adhesive or the use of a laminating adhesive with very low hardness when producing the film is an essential feature of the film.

With CO extrusion it is also possible to add the mass of the adhesion promoter to layer (3) so that layer (2) can be omitted. The film produced in this way only has 2 layers.

The layer (3) preferably consists of low density polyethylene with low rigidity. An ultra-light polyethylene with a density of less than 0.91 is advantageous, preferably the product Flexomer VLDPE series DFDA from Union Carbide Corporation Danbury Con. USA. The required soft and therefore flexible film can also be achieved by adding ethylene-vinyl acetate, known as EVA, to a low-density polyethylene known as LD-PE or to a linear low density polyethylene known as LLD-PE or to a very LOW density polyethylene known as VLD-PE; the addition of ethylene-vinyl acetate increases the flexibility of the plastic or film. The new products made using the process

The polyethylenes produced from metallocene allow a further improvement of the layer (3) of the polyethylene.

Pigments have a specific gravity of approximately 3.7 to 4.2. The type of pigment is determined by the desired opacity and covering power of the pigments and the desired color tone in the layer (3). If large amounts of very heavy pigments with a weight share of up to 70%, preferably 35% to 50%, are added to the low-density polyethylene, a heavy film that falls almost like a cloth is created from the otherwise very light polyethylene. This effect has not been known to date. A really opaque, soft, supple film is achieved with a layer thickness of 45 my from a very low-density polyethylene with 50% of the white pigment titanium dioxide type rutile. It is advantageous to extrude the layer (3) as at least a 2-layer film with the layers (3 a) and (3 b) if bright colors are desired. The top layer (3b) below layer (2) can be coated with a translucent color and is placed on a colored layer (3a) containing a higher proportion of white, so that the brilliance of the colored colors is optimized due to the lack of white covering material in the top colored layer. This film shows the figure. The low temperatures during the extrusion of polyethylene allow the use of a wide variety of colorful pigments that are free of heavy metals.

Known additives can be added to layers (1), (2) and (3) to improve the properties of the film. The main additives are:

♦ Flame retardant additives that reduce the risks of fire in the event of a fire; the requirements for building approval in accordance with fire protection regulations can be met.

♦ UV light protection additives for layer (2). If layer 3 contains a titanium dioxide of the rutile type, this acts as an excellent UV light protection additive.

♦ Antistatic agent,

♦ other additives available on the market.
230

The higher heat resistance of the materials used for the new decorative film "lacquer film" combined with the low water absorption means that the film remains as smooth as a cloth even when exposed to sunlight. A decorative film made of soft PVC becomes soft, warps and forms waves due to the absorption of moisture. The plasticizers in the soft PVC film become active when exposed to heat; if two films are placed on top of each other, they stick together slightly, similar to two glass plates placed on top of each other.

The new lacquer film described here shows essential functional properties such as,

♦ a very smooth hooking, similar to a cloth falling off a table, by using a very low density polyethylene filled with at least 35% by weight in the layer (3),

♦ an outer layer (1) that can be freely selected according to requirements and required properties,

♦ Dimensional stability when the film is used outdoors as a tablecloth, without forming folds, bubbles or waves and without softening in sunlight or sticking to other films placed on top.

♦ Reduced risk in case of fire and easier disposal.

The well-known "lacquer films" made of soft PVC are used as decorative films in interiors. PVC contains 56.7% chlorine; chlorine in plastics is considered problematic in terms of fire risks, even if flame-retardant additives are added. In

&Ggr;&Pgr; ^: &ngr;&Pgr; [C]. Often

Combustion with humidity always produces hydrochloric acid when PVC is burned and - as experience unfortunately shows - in addition to dioxin, very toxic gases that are directly dangerous to health and life. For these reasons, the new film, the decorative film as a "lacquer film", offers considerable advantages over previous decorative films. When burned, no hydrochloric acid and no dioxins are released; mainly the gases that have solidified through polymerization, such as ethylene or propylene, are burned, and in the case of a film with polyamide 12 in layer (1) some lactam or laurolactam, or in the case of a film with layer (1) made of polyester, some polyester.

The new slide with layers (1), (2) and (3) is shown in Figure 1, the one with layers (1), (2), (3a) and (3b) is shown in Figure

Dietmar Auch Aichwald, 02.09.1996

Claims (1)

&Ggr;&udigr;-«. Protection claims 1. Multilayer film as a decorative film with a high-gloss outer layer (1) made of polyester, polyamide or polypropylene, characterized in that the layer {1) achieves a gloss value of 90 or higher according to ASTM-D2457 and is permanently connected by an adhesive layer (2) to an opaque colored layer (3) with at least 15% pigment content and the layer (3) consists of a low-density polyethylene and the film made of the layers (1), (2) and (3) has a special property of being supple, almost like a starched cloth, remaining smooth when stored in damp conditions and therefore its use is used for decorative purposes such as that of a "lacquer film" or as a tablecloth. 2. Multilayer film according to claim I, characterized in that the layer (2) consists of an extruded adhesion promoter which permanently bonds all layers to one another. 3. Multilayer film according to claim 1, characterized in that the layer (2) is formed by an adhesive lamination with preferably adhesives made of polyurethane and and the layer (2) of the adhesive is characterized by low hardness and permanently bonds all layers to one another. 4. Multilayer film according to claims 1 to 3, characterized in that the high-gloss outer layer (1) reaches a thickness of at least 3 my and is made of a laurolactam, generally referred to as polylaurolactam and by ring-opening polymerization of a lactam as polyamide 12 and this is permanently connected by a layer (2) to an opaque colored layer (3) and the layer (3) consists of a low density polyethylene. 5. Multilayer film according to claims 1 to 3, characterized in that the high-gloss outer layer (1) contains portions of polypropylene. 6. Multilayer film according to claims 1 to 3, characterized in that the high-gloss outer layer (1) consists of a polyester with a thickness of at most 12 my, preferably from 5 my to 6 my. 7. Multilayer film according to claims 1 to 6, characterized in that the layer (3) consists of an ultra-light polyethylene, a very low density polyethylene (VLD-PE) with a density of 0.910 or less. 8. Multilayer film according to claims 1 and 7, characterized in that the layer (3) consists of a low density polyethylene with proportions of vinyl acetate. 9. Multilayer film according to claims 1 to 8, characterized in that the opaque colored layer (3) reaches a thickness of at least 30 my. 10. Multilayer film according to claims 1 to 9, characterized in that the opaque colored layer (3) contains pigments with 35 % by weight. 350 Hh-IfCi-CfK I i. Multilayer film according to claims i, 2 and 4 to 10, characterized in that film consisting of the layers (1), (2) and (3) is produced by the process of , 355 CO extrusion. 12. Multilayer film according to claim 11, characterized in that the film consisting of the layers (1), (2) and (3) is produced by the blown film CO extrusion process. 13. Multilayer film according to claims 2 and 4, characterized in that a plasticizer is added to the layer (1) of polyamide 12. 14. Multilayer film according to claims 1 to 2 and 4 to 8, characterized in that 365 known additives are added to the individual layers, such as fire-retardant Fabrics, antistatic agents and UV light stabilizers.