MULTI-PLY PAPER CONTAINING USED PAPER FIBERS AND ADDITIONAL FIBERS

Abstract

A paper formed of at least two layers of different compositions couched together. A first layer forms a carrier layer. A second layer forms a cover layer. The paper contains waste paper fibers and additional fibers in the form of fibers other than waste paper fibers. The additional fibers contain a proportion of fibers from the cup plant (Silphium perfoliatum). fibers from fruits and/or the barks of trees of the baobab genus (Adansonia), fibers from plants of the genus Cannabis, and/or fibers originating from residues of biogas facilities.

The carrier layer has a proportion of additional fibers equal to 0 to 75 wt %. The cover layer has a minimum proportion of additional fibers equal to about 8 wt % and a maximum proportion equal to about 80 wt %. The additional fibers in the cover layer is higher than the additional fibers content in the carrier layer.

Claims

1. Paper comprising: at least two layers of different composition which are couched together; wherein a first layer of the at least two layers forms a carrier layer; wherein a second layer of the at least two layers forms a cover layer; wherein the paper contains waste paper fibers and additional fibers in the form of fibers other than waste paper fibers; wherein the additional fibers contain a proportion of fibers from one or more of the following: a cup plant (Silphium perfoliatum); either a fruit or a tree bark of the baobab genus (Adansonia) at least one plant of the genus Cannabis; and fibers originating from a residue of biogas; wherein a proportion of additional fibers of 0 to 75 wt % is contained in the carrier layer; wherein a minimum proportion of additional fibers of 8 wt % and a maximum proportion of additional fibers of 80 wt % are contained in the cover layer; and wherein a proportion of additional fibers in the cover layer is higher than the proportion of additional fibers in the carrier layer.

2. The paper according to claim 1, wherein the proportion of additional fibers in the cover layer is at least 5 wt %; higher than the proportion of additional fibers in the carrier layer.

3. The paper according to claim 2, wherein the additional fibers are also contained in the carrier layer.

4. The paper according to claim 1, wherein the proportion of additional fibers in the carrier layer is at most 80 wt %.

5. The paper according to claim 1, wherein the proportion of additional fibers in the cover layer is 20 to 70 wt %.

6. The paper according to claim 1, wherein the minimum proportion of additional fibers in the cover layer is 25 wt %.

7. The paper according to claim 1, wherein the carrier layer has a minimum proportion of waste paper fibers of 20 wt %.

8. The paper according to claim 1, wherein the additional fibers also contain a proportion of fresh fibers and/or a proportion of grass fibers; wherein the grass fibers are in the form of fibers of sweet grass, sorrel, seagrass, or algae.

9. The paper according to claim 1, wherein the proportion of fibers of the cup plant (Silphium perfoliatum), of fibers obtained from fruits and/or the bark of trees of the baobab genus (Adansonia), of fibers originating from plants of the genus Cannabis, or originating from the residue of the biogas facilities, in a fiber composition of the cover layer makes up at least 5 wt %, relative to a dry weight of the fibers introduced overall into the cover layer.

10. The paper according to claim 9, wherein the paper contains no fresh fibers.

11. The paper according to claim 1, wherein the carrier layer contains at least one type of waste paper fibers not contained within the cover layer.

12. The paper according to claim 11, wherein waste paper fibers obtained from a white waste paper are contained in the cover layer, and a brown waste paper fibers are contained in the carrier layer.

13. The paper according to claim 11, wherein waste paper fibers of a craft paper or a craft cardboard are contained in the carrier layer.

14. The paper according to claim 1, wherein the paper has a basis weight of 80 to 200 g/m.sup.2.

15. The paper according to claim 14, wherein the carrier layer has a basis weight of 60 to 170 g/m.sup.2.

16. The paper according to claim 14, wherein the cover layer has a basis weight of 30 to 50 g/m.sup.2.

17. The paper according to claim 16, wherein an interlaminar strength determined according to the International Scott Bond Test according to DIN ISO 16260 is equal to about 180 to 300 J/m.sup.2.

18. The paper according to claim 17, wherein a Cobb.sub.60 value of the cover layer according to DIN EN ISO 535 is equal to at most 40 g/m.sup.2.

19. A method for producing a paper comprising the following steps performed in a paper machine: applying a first web of a first fibrous material composition containing water and waste paper fibers relative to a dry mass on a first screen; applying a second web of a second fibrous material composition containing water, waste paper fibers in a maximum proportion of 80 wt %, relative to the dry mass, and additional fibers in the form of fibers other than waste paper fibers in a minimum proportion of 20 wt %, relative to the dry mass on a second screen, wherein the second fibrous material composition has a higher proportion of additional fibers than the first fibrous material composition; couching the first web and the second web formed on the first screen and the second screen to form an at least two-layer paper web; drying the at least two-layer paper web; and wherein the additional fibers contain a proportion of fibers from any of the following: of a cup plant (Silphium perfoliatum), of fibers obtained from fruits and/or the bark of trees of the baobab genus (Adansonia), of fibers obtained from plants of the genus Cannabis, and/or of fibers originating from a residue of biogas facilities.

20. The method according to claim 19, wherein the first web further comprises additional fibers in the form of fibers other than waste paper fibers in a maximum proportion of 50 wt % or less relative to the dry mass.

Description

[0044] Further advantages and features of the invention emerge from the following description and from the figures referred to in this case, in which:

[0045] FIG. 1 schematically shows the production of a two-layer paper web according to the invention, assembled from a carrier layer and a cover layer containing a high proportion of additional fibers; and

[0046] FIG. 2 is a table showing possible combinations of compositions of the paper, in each case in the carrier layer (also referred to as support) and in the cover layer (also referred to as cover).

[0047] FIG. 1 schematically shows a procedure for the production of a paper according to the invention.

[0048] Here, a paper web 10, in this case, two-layered, is produced. For this purpose, a first paper layer, a carrier layer 11, is formed by applying a first fibrous material composition on a first screen of a paper machine, for example, on a lower screen. In parallel, a second paper layer, a cover layer 12, is formed by applying a second fibrous material composition on a second screen of a paper machine, for example, on an upper screen. In this case, the carrier layer 11 contains a high proportion of waste paper fibers, e.g., waste paper fibers in a proportion of at least 60 wt %, relative to the dry mass. In contrast, the cover layer 12 is characterized by a high proportion of additional fibers, specifically, at least 20 wt % in the dry mass. The proportion of additional fibers in the cover layer 12 can in particular be between 30 and 70 wt %. The carrier layer 11 can also contain additional fibers, but does not necessarily have to. The proportion of additional fibers in the cover layer should be limited to at most 50 wt %, preferably to at most 35 wt %, and in particular at most 30 wt %. In any case, the proportion of additional fibers in the cover layer 12 is higher, in particular, significantly higher, than a proportion of additional fibers in the carrier layer 11.

[0049] In any case, the additional fibers used contain fibers of the cup plant (Silphium perfoliatum), of fibers obtained from fruits and/or the bark of trees of the baobab genus (Adansonia), of fibers obtained from plants of the genus Cannabis, and/or from residues of biogas facilities. Furthermore, the additional fibers can also contain proportions of grass fibers in the form of fibers of sweet grass and/or sorrel and/or seagrass and/or algae, and/or of fresh fibers. The fact that the additional fibers contain fibers of the cup plant (Silphium perfoliatum), of fibers obtained from fruits and/or the bark of trees of the baobab genus (Adansonia), of fibers obtained from plants of the genus Cannabis, and/or from residues of biogas facilities, leads to a stability, in particular, tear strength, of the paper produced using these fibers that is clearly improved compared to the addition of pure grass fibers. This is due to the longer fibers and the higher fibril density of these particular fibers.

[0050] Preferably, if additional fibers are added to the carrier layer 11, the remainder of the dry mass in the carrier layer 11 can be formed completely by waste paper fibers. The carrier layer 11 is thus formed in a manner sufficiently stable to be able to fulfill the tear strength and also further properties required of the paper of the paper web 10.

[0051] In the cover layer 12, the proportion of fibers that is not formed by additional fibers is preferably also completely realized by waste paper fibers.

[0052] Fresh fibers are preferably avoided in both layers, the carrier layer and the cover layer. However, such fresh fibers can be contained in the layers, in particular, as components of the additional fibers. However, the proportion of fresh fibers in the mass of the additional fibers is then selected to be low, and is in particular already at most 10 wt % here, or even significantly lower, e.g., below 5 wt %, such that the proportion of such fresh fibers in the paper obtained is also correspondingly low.

[0053] Due to the high proportion of additional fibers, the cover layer 12 itself is not sufficiently stable in such a manner, and does not as such comply with the technological properties required by the paper in the paper web 10.

[0054] By bringing together the two webs of the carrier layer 11 and cover layer 12 at position 13, and the couching of the two webs performed there, the two-layer paper web 10 is then obtained which, primarily as a result of the properties of the carrier layer 11, but also due to the proportion of fibers of the cup plant (Silphium perfoliatum), of fibers obtained from fruits and/or the bark of trees of the baobab genus (Adansonia), of fibers obtained from plants of the genus Cannabis, and/or from residues of biogas facilities, exhibits the required technological properties. After further dewatering and drying, this paper web 10 is typically wound onto a paper roll 14.

[0055] The paper web 10 can in particular have a basis weight of 80 to 200 g/m.sup.2. The paper can, for example, be of a type that is implemented in a subsequent use in the production of corrugated cardboard.

[0056] The carrier layer 11 can in particular have a basis weight of 60 to 170 g/m.sup.2. The cover layer 12 can in particular have a basis weight of 30 to 50 g/m.sup.2. By adjusting the ratio of the strengths, i.e., the basis weights, of the carrier layer 11 and the cover layer 12, it is possible to adjust the required technological properties and furthermore also to adjust the proportion of additional fibers in the two-layer paper web 10 (in the case of preset proportions of additional fibers in the cover layer 12 and possibly also the carrier layer 11).

[0057] The two-layer paper web 10 preferably has an interlaminar strength, determined according to the International Scott Bond Test according to DIN ISO 16260, of 180 to 300 J/m.sup.2, and in particular of 220 to 300 J/m.sup.2.

[0058] A Cobb.sub.60 value according to DIN EN ISO 535 of at most 40 g/m.sup.2, in particular of less than 35 g/m.sup.2, and preferably less than 30 g/m.sup.2, is preferably set for the cover layer 12. This is obtained by an addition, known per se, of glue and/or starch.

[0059] In order to obtain a particular look of the cover layer 12, it can be provided, for example, that the waste paper fibers used there be fibers obtained from white waste paper. Especially in a white-based cover layer, the generally greenish or green/brownish or brownish additional fibers can be easily recognized and are thus easily perceived by the observers of a final product produced from the paper according to the invention, which has the cover layer 12 as a visible surface.

[0060] FIG. 2 shows, in the manner of a matrix or table, possible combinations of carrier layer, referred to in the figure as support, and cover layer, referred to in the figure as cover. In this case, the abbreviations used denote the following fiber components in the layers: [0061] AP: waste paper fibers, [0062] Sil o. Bio: fibers of the cup plant, fibers originating from the residues of biogas facilities, or fibers obtained from fruits and/or the bark of trees of the baobab genus (Adansonia), [0063] Hemp: fibers obtained from plants of the genus Cannabis, [0064] Grass: grass fibers obtained from dried, semi-dried, or fresh sweet grass and/or sorrel and/or seagrass and/or algae.

[0065] In the overview according to FIG. 2, nine combination ranges of carrier layers and cover layers are denoted by the crosses placed in the corresponding cells. In this case, three different possible composition ranges of carrier layers are set out, viz., starting from a carrier layer consisting of 100% waste paper, a carrier layer of the type composed of waste paper fibers and grass fibers (top row), a carrier layer assembled from waste paper, grass, and further fibers, also, optionally, fibers obtained from plants of the genus Cannabis (middle row), and a carrier layer composed of waste paper, hemp, and grass fibers (bottom row).

[0066] The respective proportions of the fibers in the differently assembled carrier layers are specified in wt % of the composition in the layer and as proportions in the dry mass, with possible ranges.

[0067] Furthermore, three possible composition ranges of the cover layer are shown, in the left-hand column with proportions of waste paper, grass, and further fibers, and, optionally, fibers obtained from plants of the genus Cannabis. In the middle column, a cover layer having a composition of waste paper, grass, and further fibers is shown. In the right-hand column, a composition range of the cover layer consisting of waste paper fibers, grass fibers, and, optionally, fibers obtained from plants of the genus Cannabis is shown.

[0068] The respective proportions of the fibers in the differently assembled cover layers are specified in wt % of the composition in the layer and as proportions in the dry mass, with possible ranges.

[0069] The advantages inherent in the paper according to the invention and the method for the production thereof are once again clear from the above description. In particular, it has become clear that the use of fibers of the cup plant (Silphium perfoliatum), of fibers obtained from fruits and/or the bark of trees of the baobab genus (Adansonia), of fibers obtained from plants of the genus Cannabis, and/or from residues of biogas facilities, firstly increases the total proportion of additional paper fibers in a paper produced on the basis of waste paper fibers, and can be adjusted in a manner that can be very freely tailored, such that, in this case in particular, a cover layer can also be obtained, which can later serve in particular as a visible surface, in which a high proportion of additional fibers obtained from rapidly renewable raw materials, which proportion is increased yet again compared with known materials, is incorporated.

LIST OF REFERENCE SIGNS

[0070] 10 Paper web [0071] 11 Carrier layer [0072] 12 Cover layer [0073] 13 Position [0074] 14 Paper roll