Method for producing a cellulose-fibre-based drinking straw

Abstract

A method for producing cellulose-fibre-based drinking straws and a drinking straw. The method comprises: providing a cellulose material, producing at least one aqueous suspension comprising the cellulose material and adding additives to the suspension, homogenizing the aqueous suspension and pre-drying to obtain at least one water-containing non-woven web having a first side and a second side, drying the water-containing non-woven web in a plurality of drying steps to form at least one paper web having a first side and a second side, further processing the paper web or a plurality of paper webs to form a cellulose-fibre-based drinking straw. At least the first side of the non-woven web is compressed with a line load of 80 kN/m to 500 kN/m before, during or after one of the drying steps and before the further processing to form a cellulose-fibre-based drinking straw.

1 . Method for producing cellulose-fibre-based drinking straws comprising the steps:
 providing a cellulose material,   producing at least one aqueous suspension comprising the cellulose material and adding additives to the suspension,   homogenizing the at least one aqueous suspension and pre-drying to obtain at least one water-containing non-woven web having a first side and a second side,   drying the at least one water-containing non-woven web in a plurality of drying steps to form at least one paper web having a first side and a second side,   further processing the at least one paper web or plurality of paper webs to form a cellulose-fibre-based drinking straw,   wherein at least the first side of the at least one non-woven web is compressed with a line load of 80 kN/m to 500 kN/m before, during or after one of the drying steps and before the further processing to form the cellulose-fibre-based drinking straw,   wherein   a cellulose mixture consisting of long-fibre sulphate cellulose and short-fibre cellulose is provided as the cellulose material, and that at least the first side of the at least one non-woven web is thermally treated in the during the compression.   
     
     
         2 . The method according to  claim 1 , wherein the at least one non-woven web is compressed of a broad-nip calender comprising a heated roller and a shoe roller cooperating with the heated roller and forming a broad nip, wherein the at least one non-woven web is guided through the broad-nip calender with its first side facing the heated roller. 
     
     
         3 . The method according to  claim 1 , wherein the at least one non-woven web is pressed by means of one or more pressure rollers with its first side onto the surface of a heated drying cylinder, wherein the at least one non-woven web is guided over a large part of the circumference of a drying cylinder and is additionally heated from outside by means of a drying hood which at least partially surrounds the drying cylinder. 
     
     
         4 . The method according to  claim 1 , wherein the cellulose mixture is prepared from 20 wt. % to 80 wt. % long-fibre sulphate cellulose and from 20 wt. % to 80 wt. % short-fibre cellulose. 
     
     
         5 . The method according to  claim 1 , wherein at least one sizing agent is added as an additive to the at least one suspension relative to the active substance of a sizing agent in a quantity of 0.07 wt. % to 1.0 wt. % relative to 100 wt. % of total dry mass of the at least one suspension. 
     
     
         6 . The method according to  claim 5 , wherein at least one sizing agent selected from a group consisting of alkenyl succinic acid anhydride (ASA), alkyl ketene dimer (AKD), resin sizes or natural sizing agents or a mixture of sizing agents selected from this group is added to the at least one suspension. 
     
     
         7 . The method according to  claim 1 , wherein the at least one suspension is produced with a consistency of 0.15% to 0.70%. 
     
     
         8 . The method according to  claim 1 , wherein during the further processing to form a cellulose-fibre-based drinking straw, one or a plurality of the paper webs are layered one above the other and joined. 
     
     
         9 . The method according to  claim 8 , wherein a compressed first side of the at least one paper web is contacted with an uncompressed second side of a further paper web layered thereover. 
     
     
         10 . The method according to  claim 8 , wherein the paper webs are glued together, wherein one adhesive is applied over the full surface or in sections to contacting sides of the paper webs. 
     
     
         11 . The method according to  claim 1  in the course of the further processing to form a cellulose-fibre-based drinking straw, the at least one paper web or a plurality of layered and joined paper webs are assembled to form paper strips, wherein in each case one paper strip is delimited by two longitudinal edges and two transverse edges, and wherein in the region of the two longitudinal edges an overlap region is formed in each case and that by bending the paper strip about a drinking straw axis, a cylindrical hollow body open on both ends is formed, wherein the paper strip is formed by overlapping the two overlap regions and the two overlap regions are glued together. 
     
     
         12 . The method according to  claim 11 , wherein the paper strip is formed so that its two longitudinal edges run substantially parallel to the axis of the drinking straw. 
     
     
         13 . The method according to  claim 11 , wherein the paper strip is formed so that the two longitudinal edges run substantially in a spiral or helical shape about the axis of the drinking straw axis. 
     
     
         14 . The method according to  claim 1 , wherein before further processing to form the cellulose-fibre-based drinking straw the first side of the at least one paper web is printed with food-safe or biologically degradable inks. 
     
     
         15 . A cellulose-fibre-based drinking straw produced according to method according to  claim 1 , comprising a cylindrical hollow body which is open on both ends having a lateral outer surface and a lateral inner surface, wherein the cylindrical hollow body is formed by at least one formed paper strip, wherein the at least one paper strip is assembled from at least one paper web having at least one compressed first side, wherein the compressed first side of the at least one paper web has a Cobb 1800s value according to ISO 535:2014 from 24 g/m 2  to 62 g/m 2 . 
     
     
         16 . The cellulose-fibre-based drinking straw according to  claim 15 , wherein a difference amount of a Cobb 1800s value according to ISO 535:2014 between the compressed first side and the non-compressed or less strongly compressed second side is a maximum of 3 g/m 2 . 
     
     
         17 . The cellulose-fibre-based drinking straw according to  claim 15 , wherein the compressed first side of the at least one paper web has a Bendtsen roughness according to ISO 8791-2:2013 of 30 ml/min to 250 ml/min. 
     
     
         18 . The cellulose-fibre-based drinking straw according to  claim 15 , wherein the at least one paper web has a gloss value according to TAPPI T 480:2015 of 20 to 35%. 
     
     
         19 . The cellulose-fibre-based drinking straw according to  claim 15 , wherein the compressed first side of the at least one paper web has a static contact angle according to ISO 19403-2:2020 using water as test liquid of 100° to 120°. 
     
     
         20 . The cellulose-fibre-based drinking straw according to  claim 15 , wherein a different amount of a static contact angle according to ISO 19403-2:2020 using water as test liquid between the compressed first side and the non-compressed or less strongly compressed second side is a maximum of 6°. 
     
     
         21 . The cellulose-fibre-drinking drinking straw according to  claim 15 , wherein at least two paper webs are arranged so that the first side of a first paper web forms the lateral outer surface of the hollow body and that a first side of the second paper web forms the lateral inner surface of the hollow body.