# US 11,078,628 B2 · Multilayer paper containing wastepaper and grass fibers > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,078,628 B2 - Document ID: US11078628B2 - Status: Granted - Kind: B2 - Application number: 16/735,735 - Filed: 2020-01-07 - Published: 2020-07-16 - Granted: 2021-08-03 - Earliest claimed: 2019-01-15 - Assignees: Papierfabrik Meldorf GmbH & Co. Kommanditgesellschaft - Applicants: Papierfabrik Meldorf GmbH & Co. Kommanditgesellschaft; Hans Wehrmann - Inventors: Martin Pflug; Hans Wehrmann - Web page: https://patentgrep.com/patent/US11078628B2 ## CPC - D21H 15/10: Composite fibres - D21H 27/30: Multi-ply (for surface covering D21H27/18; making on paper-making machines D21F9/00, D21F11/00) - D21F 9/006: {paper or board consisting of two or more layers} - D21H 11/12: Pulp from non-woody plants or crops, e.g. cotton, flax, straw, bagasse - D21H 11/14: Secondary fibres (working-up waste paper D21C5/02) - D21H 27/10: Packing paper (packaging materials of special type or form B65D65/38) - D21H 27/38: at least one of the sheets having a fibrous composition differing from that of other sheets - D21H 27/40: at least one of the sheets being non-planar, e.g. crêped (crêping or corrugating paper B31F) - Y02W 30/64: Paper recycling - D21H: PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR - D21F: PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON - Y02W: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT ## Abstract A paper (10) is disclosed, especially for use in the production of corrugated cardboard. The paper (10) is formed from at least two layers couched together and having different composition and it contains wastepaper fibers and grass fibers. The special feature of the paper is that a first layer of the paper (10) is formed as a support layer (11) and contains a maximum fraction of 30 wt. % of grass fibers, a second layer of the paper (10) forms a top layer (12) with a minimum fraction of 20 wt. % of grass fibers and a maximum fraction of 80 wt. % of wastepaper fibers, and the fraction of grass fibers in the top layer (12) is higher than the fraction of grass fibers in the support layer (11). ## Claims ### Claim 1 A paper, especially for use in the production of corrugated cardboard, wherein the paper comprises at least two layers couched together and having different composition and wherein the paper contains wastepaper fibers and grass fibers, wherein a first layer of the at least two layers of the paper is formed as a support layer and contains a maximum fraction of 30 wt. % of grass fibers, a second layer of the at least two layers of the paper forms a top layer with a minimum fraction of 20 wt. % of grass fibers and a maximum fraction of 80 wt. % of wastepaper fibers, and the fraction of grass fibers in the top layer is higher than the fraction of grass fibers in the support layer. ### Claim 2 (depends on 1) The paper according to claim 1, wherein the fraction of grass fibers in the top layer is at least 5 wt. % higher than the fraction of grass fibers in the support layer. ### Claim 3 (depends on 2) The paper according to claim 2, wherein the fraction of grass fibers in the top layer is at least 10 wt. % higher than the fraction of grass fibers in the support layer. ### Claim 4 (depends on 2) The paper according to claim 2, wherein the fraction of grass fibers in the top layer is at least 15 wt. % higher than the fraction of grass fibers in the support layer. ### Claim 5 (depends on 1) The paper according to claim 1, wherein the fraction of grass fibers in the support layer is at most 25 wt. %. ### Claim 6 (depends on 5) The paper according to claim 5, wherein the fraction of grass fibers in the support layer is at most 20 wt. %. ### Claim 7 (depends on 1) The paper according to claim 1, wherein the fraction of grass fibers in the top layer is from about 20 wt. % up to about 70 wt. %. ### Claim 8 (depends on 1) The paper according to claim 1, wherein the minimum fraction of grass fibers in the top layer is 25 wt. %. ### Claim 9 (depends on 8) The paper according to claim 8, wherein the minimum fraction of grass fibers in the top layer is 30 wt. %. ### Claim 10 (depends on 8) The paper according to claim 8, wherein the minimum fraction of grass fibers in the top layer is 35 wt. %. ### Claim 11 (depends on 8) The paper according to claim 8, wherein the minimum fraction of grass fibers in the top layer is 40 wt. %. ### Claim 12 (depends on 1) The paper according to claim 1, wherein the support layer has a minimum fraction of wastepaper fibers of 70 wt. %. ### Claim 13 (depends on 1) The paper according to claim 1, wherein the paper contains no virgin fibers. ### Claim 14 (depends on 1) The paper according to claim 1, wherein the at least two layers contain different kinds of wastepaper fibers. ### Claim 15 (depends on 14) The paper according to claim 14, wherein the top layer contains wastepaper fibers obtained from white wastepaper and the support layer contains brown wastepaper fibers. ### Claim 16 (depends on 14) The paper according to claim 14, wherein the support layer contains wastepaper fibers of kraft paper or kraft cardboard. ### Claim 17 (depends on 1) The paper according to claim 1, wherein the paper has a weight per unit area of from about 80 g/m2 up to about 200 g/m2. ### Claim 18 (depends on 17) The paper according to claim 17, wherein the paper has a weight per unit area of from about 125 g/m2 up to about 175 g/m2. ### Claim 19 (depends on 1) The paper according to claim 1, wherein the support layer has a weight per unit area of from about 60 g/m2 up to about 170 g/m2. ### Claim 20 (depends on 1) The paper according to claim 1, wherein the top layer has a weight per unit area of 30 g/m2 to 50 g/m2. ### Claim 21 (depends on 1) The paper according to claim 1, wherein the paper has a cleavage strength determined by the International Scott bond test per DIN ISO 16260 of from about 180 J/m2 up to about 300 J/m2. ### Claim 22 (depends on 21) The paper according to claim 21, wherein the paper has a cleavage strength determined by the International Scott bond test per DIN ISO 16260 of from about 220 J/m2 up to about 300 J/m2. ### Claim 23 (depends on 1) The paper according to claim 1, wherein the paper has a Cobb60 value of the top layer per DIN EN ISO 535 of at most 40 g/m2. ### Claim 24 (depends on 23) The paper according to claim 23, wherein the paper has a Cobb60 value of the top layer per DIN EN ISO 535 of less than 35 g/m2. ### Claim 25 (depends on 23) The paper according to claim 23, wherein the paper has a Cobb60 value of the top layer per DIN EN ISO 535 of less than 30 g/m2. ### Claim 26 A method for production of a paper with the following steps carried out in a paper making machine: placement of a first fiber composition containing water, grass fibers in a maximum fraction of 30 wt. % or less, in terms of the dry weight, as well as wastepaper fibers, in the form of a web on a first screen; placement of a second fiber composition containing water, grass fibers in a minimum fraction of 20 wt. % or less, in terms of the dry weight, as well as wastepaper fibers in a maximum fraction of 80 wt. %, in terms of the dry weight, in the form of a web on a second screen, wherein the second fiber composition has a higher fraction of grass fibers than the first fiber composition; couching of the webs formed on the first and second screens to produce an at least two-layer paper web; and drying of the paper web.