Recyclable and biodegradable, heat- and cold-resistant laminate, preferably for food packaging

p0001The present invention relates to a recyclable and biodegradable grease, heat and frozen resistant laminate having two or more layers, in particular for storage, for freezing, warm up and / or for baking food.

p0002A general problem with the packages or containers for food storage in use today is their disposal. In most cases, the packaging is a composite of paper or cardboard and one or more layers of plastic or metal. Since a subsequent separation of the layers is practically impossible, such packaging or container for disposal in a waste incineration plant must be burned. At a deposition of the containers on landfills while rotting the paper or cardboard, but remains the plastic or metal laminate.

p0003EP-A-0244179 describes as a paper container with a paper layer which is provided on both sides with a heat-resistant layer of epoxy acrylic plastic. The advantage of this container is its good heat resistance. By adding a pigment to the heat-resistant plastic layer discoloration of the paper can be made optically invisible high heat. A disadvantage of the container is that a separation of the paper-plastic composite after use is no longer practicable or would be too costly. The container thus is not suitable for recycling. In addition, he is also not biodegradable.

p0004EP-A-0245005 discloses a paperboard container having an improved flame resistance which outside, that is on the side facing away from the food, is provided with a paper which has a non-flammable coating coated. The carton and the paper layer are bonded together by an adhesive, typically polyvinyl acetate. On the inside of the carton with a food-compliant plastic such as polyethylene terephthalate, coated. This vessel is engaged in manufacturing relatively expensive and also not recyclable.

p0005EP-A-0542143 discloses a packaging material made of multilayer composite materials, which are fully compostable. The packaging material consists of a base layer of a conventional paper or cardboard with a high recycled content, which is coated on one or both over a layer of glue with a food allowable paper. The product-facing side is made of a laminate layer of intense ground cellulose, water-soluble polysaccharides which are added and which has been compressed in a supercalender. The containers manufactured from the composite material to be used as a baking tray and are also suitable for the storage of fatty foods. Due to the high calendering a sufficient anti-adhesive effect is achieved, so that can be obviously omitted special coatings.

p0006EP-A-0494077 discloses a package for storing degradable and holding of prepared food, 100% and recyclable material. The packing has an outer paper base layer, on the inner side thereof by an adhesive a substantially air- and water fettundurchlässige barrier layer of transparent paper is arranged. On the said barrier layer an outer metal layer having a low emissivity is applied. However, containers with metal coatings have the disadvantage that they are not suitable for heating food in microwave ovens.

p0007Packages or containers which are suitable for the storage, deep freezing and warming up of food, usually have the disadvantage that they can not be used universally. Thus, for example containers having an aluminum coating, not heated in microwave ovens only in conventional electric oven, respectively, received therein food to be baked. Container without metal coatings in turn are indeed microwave compatible, but often not to such an extent heat-resistant that they could be used in an electric furnace. In addition usually takes the already initially mentioned problem of biodegradability. Just Disposable tableware is often left lying in nature, so it comes with time to an accumulation of biologically undegraded waste.

p0008A distinction of the biodegradability is the recyclability of a product. Today's efforts go in the direction to modify plastics so that this example can be degraded by naturally occurring bacteria and / or by sunlight. These efforts therefore focused almost exclusively on the problem of the biodegradability of substances. At a recycling of products is not intended. Especially with disposable tableware and disposable packaging for food products would be particularly advantageous if this would not only biodegradable, but could also be recycled. Thus, the resulting in the so-called "fast food" chains packaging could be largely recycled.

p0009Object of the present invention is to provide a laminate, which does not have the disadvantages mentioned above. The laminate should especially recyclability and biodegradable, and free of grease, heat and be frozen resistant, so it can be prepared as a container for freezing, heating and baking food.

p0010According to the invention, a laminate of the aforementioned type is characterized by a first layer or support layer made of cardboard, made from mechanically crushed pulp, a single- or multi-ply paper, pulp or secondary fibers, at least a second layer of a food-compliant, grease and heat-resistant paper, a adhesive for connecting the first and the second layer, and another on the food-compliant, grease resistant paper (15) provided protective layer (19) as a non-stick coating. Unlike known packages is such a laminate consisting of pulp substantially, both biodegradable and fully recyclable. Moreover, food can be stored in made of the laminate of this invention containers are frozen and / or heated or baked. The heating of the food can take place in conventional electric furnaces or in microwave ovens.

p0011The full recyclability of the laminate results from the fact that this practice consists of only pulp. The laminate can therefore - in contrast to the containers described in the introduction - such as waste paper to be recycled. Equally important, however, appear that the existing pulp laminate is completely biodegradable in nature.

p0012The essentially consisting of cellulose and grease Heat resistant paper layer is conveniently produced by intensive mechanical refining of the pulp. In this manufacturing process, the surface of the fibers is so greatly enlarged that a particularly fine-pore paper is produced which is practically impermeable to fat molecules. The average porosity of the paper is thus less than the size of the fat molecules. The grease resistance can be measured by the Linden tests. A Linden indicates the time in seconds it takes for an air volume of 0.318 cubic centimeters to a paper surface of 37 cm² to penetrate. The air is thereby under an air pressure of 100 mm Hg, has a temperature of 20 ° C and a moisture content of 65%. Usefully, owns the paper layer is a grease resistance of more than 6 seconds or Linden, preferably> 8 seconds (Linden) and very particularly preferably> about 10 seconds (Linden)

p0013Suitably, the carrier layer is made of cardboard, painted (eg kaolin, BaCO₃BaS O₄ etc.) or rough paper or a multi-ply formed. The inventive laminate can be produced inexpensively by gluing rolls of cardboard and grease and heat-resistant paper. As adhesive may be used for example starch. Also conceivable, however, other, preferably degradable (environmentally friendly) and food safe adhesives. Production costs are therefore very low in practice. The backing layer of the inventive laminate may also at least partially made of already recycled paper, so it can be made available at low cost. The inventive laminate also has the advantage that the board or the paper layer can be printed.

p0014When laminate of this invention determines the cardboard layer which may also consist of a thick paper, to a large extent the mechanical properties, especially the stiffness of the container. The caring for the strength cardboard or paper layer may itself be composed of several layers. However, it is also conceivable that in cases where the laminate special packaging purposes, the support layer and the heat and grease-resistant layer are approximately the same thickness. The arranged on the cardboard layer of grease and heat-resistant paper layer provides the fat and heat resistance and food compatibility.

p0015Advantageously, the adhesive strength. Starch is food grade, has good adhesion to paper or cardboard and is largely resistant to heat. Furthermore, starch is also biodegradable. The container can thus be practically completely produced from natural raw materials. It can be used as a starch or artificial, preferably biodegradable adhesives but other adhesives. the adhesives or glues used are advantageously degradable or soluble and do not interfere with the recycling of the laminate.

p0016In a particularly advantageous embodiment, the carton respectively the thick paper layer (= base layer) is provided on both sides with heat and grease resistant paper. This has the advantage that discoloration or charring of the carton in the hot oven can be largely prevented. However, it is also conceivable that the cardboard layer is provided on one side with the grease and heat-resistant paper, and on the other side with ordinary paper. Preferably, the paper layer is additionally water and oxygen. This allows the flavor of the stored in the container and then heated foods can be obtained.

p0017Advantageously, the heat and grease resistant paper and / or cardboard layer on at least a protective layer. Expediently has the heat and grease resistant paper layer such as a silicone, Quilon- or similar coating. The silicone coating resp. Siliconizing the paper layer by applying 0.3. to lg, preferably about 0.5g Silicone manufactured. Such paper has expediently a grease resistance of about 10 Linden. The coating has the advantage that it is water-repellent u nd can prevent sticking of food on paper. Incidentally is increased by the silicone treatment and the ignition temperature of the paper layer. Such crowds clad laminate is surprisingly excellent for fresh baked goods that are purchased in the frozen state at more than 200 ° C is heated in the oven. The container from the laminate of this invention can even be used several times because of the high heat resistant properties and surprisingly good grease resistance.

p0018The protective layer may be for example made of a water-soluble suspension. the protective layer advantageously contains a pigment. With the help of this dye a possible discoloration of paper or board in the hot furnace can be made optically largely invisible.

p0019The support layer and the heat and grease resistant paper layer can according to use different strengths have. Usually, the strengths are chosen so that it is possible in a press produce rigid containers.

p0020From the laminate described above, recyclable and biodegradable disposable tableware for use in electrical and / or microwave ovens can be produced.

p0021Exemplary embodiments of the invention are described with reference to the figures. It shows:<dl id="dl0001"><dt>Fig. 1</dt><dd>a first embodiment of an inventive laminate of a layer of cardboard and a grease and heat-resistant layer of paper in section;</dd><dt>Fig.2</dt><dd>a second embodiment of a laminate of a layer of cardboard and on both sides applied grease and heat-resistant layer of paper, also in section;</dd><dt>Fig. 3</dt><dd>the embodiment of Figure 1 with a protective layer; and</dd><dt>Fig. 4</dt><dd>an embodiment of a grease and heat-resistant paper layer on one side and an ordinary paper on the other side.</dd></dl>

p0022The laminates 11,11 ', 11 "of Figures 1 to 3 consist of a cardboard or carrier layer 13 and one or two layers of paper 15 (Fig. 1, respectively. Fig. 2). The support layer 13 and the grease and heat-resistant layers of paper 15 are represented by an adhesive, such as starch, in the figures as intervening layer of glue 17, fixed together. in this case, the laminates of figures 1, the support layer 13 the necessary stability and the paper layer 15 for the fat and heat resistance and water repellency or waterproofing makes. and 2 are siliconized advantageous (in the figures not visible.) the package of FIG. 3 has a silicone layer 19 on. the figures 1 to 3 do not represent masstäbliche representation of the layers. Thus, for example the glue layer 17 and the silicone layer 19 in comparison be substantially thinner with the other.

p0023The embodiment according to Figure 4 differs from the embodiment according to Figure 2 is that an ordinary paper layer 21 is arranged on one side instead of the grease and heat-resistant paper layer. Other combinations of carrier and layers of paper are also conceivable.

p0024The inventive recyclable laminate is preferably prepared by rolling of cardboard and grease resistant paper are glued together. For this, the cardboard tube is first with glue, for example, starch, for example coated. Then, the paper roll is pressed on the cardboard roll. The production of containers can be carried by means of corresponding shapes on known machines. A particularly cost-effective, is commercially available, with silicone baking paper applied to at least one side of the cardboard backing.

p0025Papers that are suitable for the preparation of the novel packaging, for example, natural, ie, obtained by mechanical refining cell fibers papers, which are available on the market. The papers may be made of pure (eg sulphate) pulp or cellulose fibers and are used in various grades. The papers can be bleached or unbleached also.

p0026Particularly suitable is a substrate coated with about 0.5 g silicone baking paper with an ignition temperature of> about 260 ° C, preferably> about 280 ° C. The ignition temperature is measured by placing a piece of paper of about 0.01 m² is placed on a non-flammable surface in a furnace, which is heated with eienr rate of 5 ° C / minute.

p0027inexpensive food containers, cups, dishes, oven-proof dishes, bakeware and microwave dishes can be prepared for example by die cutting or embossing from the laminate. The dishes produced is biodegradable and recyclable.