Use of at least one layer of cellulose wadding for the manufacture of transformed products

Abstract

According to the invention, to solve the problem of providing a recyclable and non-climate-damaging material for the manufacture of formed products, the use of at least single-layer cellulose wadding comprising cellulose in the form of a web or in the form of blanks for the manufacture of formed products is proposed.

Description

[0001] Use of at least one layer of cellulose wadding for the production of formed products

[0002] The present invention relates to the use of at least one-layer cellulose wadding for the production of formed products.

[0003] Pulp is obtained by breaking down plant fibers and consists essentially of cellulose. A wide variety of products are made from pulp, such as paper, tissue products, diapers, etc. Pulp is available in various qualities. For example, bleached or unbleached pulp or raw material obtained from waste paper is used for a variety of applications. This can be used to make cellulose wadding. After dissolving the pulp or raw material from waste paper in water in a pulper, a mechanical treatment and subsequent dewatering results in a product that is dried. This then undergoes further mechanical treatment in the paper machine to produce cellulose wadding, particularly by imparting a high crepe finish.

[0004] Cellulose wadding is a special quality and is made from softwoods, sometimes also from hardwoods. Cellulose wadding has good water-binding properties and is therefore primarily used for hygiene products such as sanitary pads, incontinence products, and the like.

[0005] Formed products within the meaning of the present invention are used in particular as packaging materials. These can be in the form of so-called trays or bowls, which hold sausage, cheese, or fruit, for example, or in the form of blisters or similar. These are usually made of plastic or plastic substitutes and generally contain chemical additives and, in particular, surface seals to prevent the packaging from becoming soggy, especially in the case of plastic substitutes. Packaging products in the form of plastics, but also coated plastic substitutes, regardless of the material, are difficult to recycle, particularly when they are multi-layer packaging products, and are therefore generally thermally recycled, for example, incinerated.It would therefore be desirable to provide packaging products that could not only be thermally recycled but, in particular, also be meaningfully recycled. Furthermore, it is desirable to manufacture packaging products from materials that have a low carbon footprint and are made from renewable raw materials, for example.

[0006] It is therefore an object of the present invention to provide formed products, which can be used in particular as packaging, which are recyclable and at the same time are less harmful to the climate, in particular climate-neutral, compared to existing generic products.

[0007] This object is achieved according to the invention by the use of at least one-layer cellulose wadding comprising cellulose in the form of a web or in the form of blanks for the production of formed products. The term "formed products" in the context of the present invention is understood in particular to mean, for example, that a web or blank of cellulose wadding is hot- or cold-formed using pressure. If necessary, a vacuum can also be used. The individual layer of cellulose wadding as a raw product is thereby formed into a semi-finished product or a finished product, for example a packaging container. Typical processing temperatures can range from approximately 10°C to approximately 450°C, preferably from approximately 50°C to approximately 400°C, even more preferably from approximately 175°C to approximately 375°C.In addition to the application of pressure, tension can also be exerted on the web or blank made of cellulose wadding during the production of formed products, so that in this sense one can also speak of tensile compressive forming, here with reference to cellulose wadding. However, pure compressive forming, for example by rolling or in the manner of die forming, is also possible with a web or blank made of cellulose wadding within the meaning of the present invention in order to use them for the production of formed products. The cellulose wadding used is preferably made from softwood, in particular coniferous wood. Preferably, the at least single-layer cellulose wadding comprises long-fiber cellulose. More preferably, the cellulose used to produce the cellulose wadding has a fiber length in a range from approximately 1 mm to approximately 5.5 mm, more preferably in a range from approximately 2 mm to approximately 5 mm, and even more preferably in a range from approximately 2.5 mm to approximately 4.5 mm.The fiber length of the pulp used is preferably retained in the cellulose wadding.

[0008] Cellulose wadding in the sense of the present invention, which is used for the production of formed products, in the form of a single layer has a crepe factor in a range of about 15% to about 80%, more preferably in a range of about 35% to about 75%, and a basis weight in a range of about 16g / m 2 up to about 50 g / m 2 The aforementioned crepe factor is very high and distinguishes cellulose wadding from other pulp-derived products. It is preferably made from bleached and unbleached pulp or from waste paper, more preferably from unbleached pulp or from waste paper. Blends of bleached pulp and / or unbleached pulp and / or waste paper raw material can also be used, depending on the requirements of the converted products.

[0009] If, within the scope of the present invention, the term "approximately" or "substantially" is used in connection with values ​​or value ranges, or with properties or geometries, this is to be understood as a tolerance range that a person skilled in the art considers customary in this field. In particular, a tolerance range in connection with values ​​or value ranges when using the term "approximately" of + / - 20%, preferably + / - 10%, and more preferably + / - 5% is provided. Lower limits of value ranges can be undercut by 5% to 20%. Upper limits of value ranges can be exceeded by 5% to 20%. To the extent that different value ranges, for example preferred and more preferred value ranges, are specified in the present invention, the lower limits and upper limits of the various value ranges can be combined with one another.

[0010] The formed products produced using at least one layer of cellulose wadding are preferably packaging materials. These can be designed, in particular, in the form of trays, blisters, bags, containers, etc. The packaging materials are preferably suitable for packaging food. However, other products can also be packaged with them, for example, pharmaceutical products, cosmetics, medical devices, technical devices, and drugstore items, with the aforementioned products being mentioned as examples.

[0011] The particular advantage of the inventive use of at least one-layer cellulose wadding for the production of formed products is that it provides formed products made exclusively from renewable raw materials and leaving virtually no carbon footprint. Above all, these products are also recyclable, as they do not require the coatings otherwise required for food products. They can therefore be collected separately with other paper waste and appropriately recycled.

[0012] The at least single-layer cellulose wadding can contain other fiber materials besides cellulose, which are mixed in during production. The at least single-layer cellulose wadding can particularly preferably contain a proportion of cotton fibers. Suitable cotton fibers advantageously have a fiber length in a range of about 1 mm to about 25 mm. However, fibers from hemp, bamboo or other renewable raw materials can also be used. The fiber length of the other fiber material is preferably in a range of about 1 mm to about 25 mm, more preferably in a range of about 1.5 mm to about 10 mm, and even more preferably in a range of about 2 mm to about 8 mm. The proportion of other fiber materials as mentioned above in the at least single-layer cellulose wadding for the production of unshaped products is in a range of about 1 wt.% to about 50 wt.%, more preferably in a range of about 2 wt.% to about 40 wt.-%, and even more preferably in a range of about 10 wt.% to about 35 wt.%, based on the total amount of cellulose wadding.

[0013] The formed products manufactured using at least one layer of cellulose wadding can also have a multi-layer structure. For example, one or more layers of an airlaid material (non-woven material, such as a fleece material) can be arranged on one or more layers of cellulose wadding arranged on each side of the airlaid layer, or conversely, one or more layers of cellulose wadding can be arranged between one or more layers of an airlaid material arranged on both sides of the cellulose wadding. However, other types of multi-layer products can also be manufactured using at least one layer of cellulose wadding.The inventive use of at least one-layer cellulose wadding for the production of formed products, in particular packaging materials, provides a novel application for pulp and thus cellulose wadding. The inventive use of the at least one-layer cellulose wadding in forming processes for the production of semi-finished products or finished products from the raw material cellulose wadding, in particular in the context of compression forming or tensile compression forming, preferably tensile compression forming at elevated temperatures, surprisingly allows for the production of high-quality products with excellent properties as packaging materials, making them particularly suitable for use in the food industry.

[0014] Deep drawing is advantageously the preferred tensile-compression forming process, whereby the at least single-layer cellulose wadding is fed in the form of a web or in the form of blanks into a corresponding device and drawn into hollow molds under pressure. Advantageously, the products are manufactured in the forming process at the temperatures specified above and under pressure. For example, a forming die with a specific pressure, for example, in a range of approximately 10 bar to approximately 100 bar, can be used, based on the part to be formed.

[0015] Advantageously, the at least one layer of cellulose wadding has a thickness according to DIN EN ISO 12625-3 (September 2014) in a range from approximately 0.12 mm to approximately 0.68 mm, more preferably in a range from approximately 0.15 mm to approximately 0.55 mm. These specifications refer to the at least one layer of cellulose wadding prior to the production of a formed product. Advantageously, cellulose wadding in the form of a web or in the form of blanks, generally formed in multiple layers, in particular at least four layers, for the production of formed products which are fed to the forming process, has a thickness according to DIN EN ISO 12625-3 (September 2014) before forming in a range from about 0.5 mm to about 70 mm, preferably in a range from about 1 mm to about 55 mm, more preferably in a range from about 1.5 mm to about 40 mm, and even more preferably in a range from about 1.6 mm to about 15 mm.Due to creping of the at least one-layer cellulose wadding, the thickness of a single layer of the cellulose wadding, which is generally multi-layered and in particular at least four-layered and is fed into the forming process, cannot be used to determine the thickness of the cellulose wadding.

[0016] In a preferred embodiment, cellulose wadding is used which is formed of at least four layers. The number of layers can consist of individual, superimposed layers or can be achieved by folding back a layer. For example, a four-layer cellulose wadding which has been created by doubling can be produced by folding back a single layer of cellulose wadding twice, or by stacking four individual layers of cellulose wadding on top of one another, which is preferred, or by folding back a single layer once and stacking two such resulting double layers on top of one another. Advantageously, the cellulose wadding used to produce formed products is formed of at least eight layers, more preferably at least ten layers, and even more preferably at least sixteen layers.A sixteen-ply cellulose wadding can be produced by stacking eight double layers of cellulose wadding, with each double layer being obtained by folding back a single layer. The basis weight of a layer of cellulose wadding is advantageously in the range of approximately 16 g / m. 2 up to about 50 g / m 2 , more preferably in a range of about 20 g / m 2 up to about 42 g / m 2 .

[0017] The cellulose wadding used according to the invention advantageously has a crepe factor in a range from about 15% to about 80%, more preferably in a range from about 35% to about 75%, and even more preferably in a range from about 40% to about 70%. Creping is achieved by varying the drive speed of cylinders in a paper machine, in particular between the drying cylinder and the reel (Pope reel), on which the cellulose wadding to be used according to the invention is produced. For example, a crepe factor of about 50% is obtained if the reel runs about 50% slower than the drying cylinder. The crepe factor is thus also a measure of the (breaking) elongation of the finished, at least single-layer cellulose wadding according to the present invention.However, the elongation is also influenced by other factors during production, for example, by the settings of a doctor blade angle in the paper machine when scraping the produced cellulose wadding from a drying cylinder. The crepe factor of the cellulose wadding used according to the invention can be described as very high compared to crepe factors of other materials made from cellulose. In conjunction with other factors, particularly the basis weight, it ensures a uniform appearance of the formed products during production, especially their surface, and, particularly when using multi-layer cellulose wadding, very light but sufficiently strong formed products.

[0018] The cellulose wadding to be used according to the invention preferably has a moisture content according to DIN 54540 Part 9 (2007-10) in a range from about 3% to about 40%, more preferably in a range from about 5% to about 35%, even more preferably in a range from about 8% to about 32%, and even more preferably in a range from about 10.5% to about 29%. Provision can be made for the cellulose wadding to be additionally moistened after production in a paper machine in order to achieve higher moisture contents. Moisture can also take place subsequently in a forming machine or in a process upstream of this.Humidification can be carried out, for example, by adding water or another liquid to the cellulose wadding before placing three single-layered cellulose wadding on top of one another, preferably only to the inner layer, for example by spraying water onto at least one side of the layer in question after the cellulose wadding has been produced and before it is placed on top of one another or folded back and rolled up. This keeps the moisture inside the then three-layered cellulose wadding web. However, the outer layers of multi-layered cellulose wadding can also be moistened. With regard to the inventive use of the at least single-layered cellulose wadding for the production of formed products, a moisture content is preferably adjusted with water. In addition, however, other substances can also be added in order to impart certain characteristics to the formed products produced.For example, grease or oil-repellent agents can be applied to the at least single-layer cellulose wadding, preferably when the at least single-layer cellulose wadding is lined, to the inner surface of the cellulose wadding after lining. Particularly preferably, the cellulose wadding used according to the invention is treated with at least one water- and / or oil-repellent agent. This agent is further preferably biodegradable and / or compostable, and particularly preferably comprises silicon oxide compounds. Advantageously, the at least single-layer cellulose wadding used for the production of formed products has an elongation at break according to DIN EN ISO 12625-4 (March 2017) in a range from approximately 15% to approximately 180%, further preferably in a range from approximately 30% to approximately 120%, and even more preferably in a range from approximately 40% to approximately 95%.The crepe factor in the last-mentioned particularly preferred range is preferably about 45% to about 55%. Such values ​​for the elongation at break and the crepe factor are set in particular when exclusively cellulose wadding is used in each layer. An elongation at break in a range of about 15% to about 40% is preferably associated with a crepe factor of about 15% to about 28%. Such values ​​for the elongation at break and the crepe factor are set in particular when at least one single-layer cellulose wadding, which forms outer layers, is combined with an at least one-layer inner layer made of an airlaid material. With an elongation at break in the aforementioned ranges, the production of products by forming processes, in particular packaging materials, in particular within the framework of a deep-drawing process using heat, is advantageously enabled.

[0019] In a preferred embodiment of the at least single-layer cellulose wadding to be used, in a multi-layer configuration, the moisture content of at least one inner layer prior to forming into formed products is higher than the moisture content of an outer layer. Preferably, in a multi-layer configuration, the outer layers of the cellulose wadding are not moistened after the production of the cellulose wadding, whereas inner layers can be moistened after the production of the cellulose wadding, in particular after leaving the paper machine, in order to be able to adjust the moisture content desired for the forming of the products.Preferably, as described above, during a refolding or stacking of at least one layer of cellulose wadding, at least one side of the wadding is moistened and then this first layer is folded back, or a second layer of cellulose wadding is applied, which can also have been moistened on at least one side, preferably on the side facing the first layer, so that the moisture content inside the then at least two-layer cellulose wadding is increased. A similar procedure can be followed for multiple refolding or multiple stacking of individual layers of cellulose wadding. Layers to be arranged centrally can preferably be moistened from both sides.

[0020] As already mentioned above, the formed products are advantageously manufactured using a deep-drawing process. This is preferably carried out by applying pressure and heat in the aforementioned areas.

[0021] The above and further advantages of the present invention are explained in more detail using the following embodiment.

[0022] Highly bleached long-fiber softwood pulp with a fiber length of 3 mm to 4 mm is first formed into a pulp by digestion with water in a pulper. The resulting pulp-water mixture is fed to a paper machine and applied to a continuous screen. Directly at the beginning of the paper machine, a vacuum-operated suction breast roll removes a large portion of the water from the pulp-water mixture, thus forming cellulose wadding on the continuous screen. Additional dewatering elements in the paper machine ensure further drying of the resulting single-ply cellulose wadding. The still-moist, single-ply cellulose wadding is couched off the continuous screen via a couch and transported to a downstream drying section of the paper machine. This section includes, in particular, a steam-heated drying cylinder and a steam hood that dries the single-ply cellulose wadding with hot air.The resulting single-ply cellulose wadding had a moisture content of approximately 3% to approximately 6.5% according to DIN EN ISO 12625-8 (April 2011). It was scraped off the drying cylinder and wound up. During winding, a crepe factor of approximately 45% to approximately 55% was achieved by varying the speed between the drying cylinder and the reel used for winding. The elongation at break of the resulting single-ply cellulose wadding was approximately 60% to approximately 85% according to DIN EN ISO 12625-4 (March 2017). The basis weight of the single-ply cellulose wadding sheet was approximately 31 g / m². 2After removing the single-layer cellulose wadding produced as described above, it was formed into eight layers by folding one layer of cellulose wadding back four times or by unrolling eight individual layers of cellulose wadding and stacking them on top of each other. Water was sprayed onto the inner layers of the cellulose wadding to achieve a moisture content of approximately 20% for the eight-layer cellulose wadding. Finally, the eight-layer cellulose wadding, which had a thickness of approximately 2.8 mm, was cut into narrow rolls.

[0023] A cellulose wadding produced in this way can then be formed, for example, by folding back or laying two webs of eight-layer cellulose wadding on top of each other, thus forming a total of sixteen layers, in a deep-drawing-like process into, for example, a tray for packaging fruit, sausage or cheese.

Claims

Patent claims 1. Use of at least a single layer of cellulose wadding comprising cellulose in the form of a web or in the form of blanks for the manufacture of formed products.

2. Use according to claim 1, characterized in that the at least single-layer cellulose wadding comprises long-fiber cellulose.

3. Use according to one or more of the preceding claims, characterized in that the products are packaging materials.

4. Use according to one or more of the preceding claims, characterized in that the cellulose used to produce the cellulose wadding has a fiber length in a range of about 1 mm to about 5.5 mm.

5. Use according to one or more of the preceding claims, characterized in that a layer of the cellulose wadding has a thickness according to DIN EN ISO 12625-3 (September 2014) in a range of about 0.12 mm to about 0.68 mm.

6. Use according to one or more of the preceding claims, characterized in that the cellulose wadding has a thickness according to DIN EN ISO 12625-3 (September 2014) in a range of about 0.5 mm to about 70 mm before forming.

7. Use according to one or more of the preceding claims, characterized in that the cellulose wadding is formed in at least four layers.

8. Use according to one or more of the preceding claims, characterized in that the at least single-layer cellulose wadding has a basis weight in the range of approximately 16 g / m². 2 up to about 50 g / m² 2 exhibits. Use according to one or more of the preceding claims, characterized in that the cellulose wadding has a crepe factor in the range of approximately 15% to approximately 80%. Use according to one or more of the preceding claims, characterized in that the cellulose wadding has a moisture content according to DIN EN ISO 12625-8 (April 2011) in the range of approximately 3% to approximately 40%. Use according to one or more of the preceding claims, characterized in that the cellulose used to produce the cellulose wadding is bleached and / or unbleached. Use according to one or more of the preceding claims, characterized in that the cellulose wadding has an elongation at break according to DIN EN ISO 12625-4 (March 2017) in the range of approximately 15% to approximately 180%.Use according to one or more of the preceding claims, characterized in that, in a multi-layered configuration, the cellulose wadding has a moisture content of at least one inner layer higher than the moisture content of the outer layers before forming. Use according to one or more of the preceding claims, characterized in that the products are manufactured by a deep-drawing process.