Process for the production of gel-based composite materials

Abstract

A process for the production of composite materials comprising nano-fibrillar cellulose gels, by providing cellulose fibres and at least one filler and/or pigment, combining the cellulose fibres and the at least one filler and/or pigment, fibrillating the cellulose fibres in the presence of the at least one filler and/or pigment until a gel is formed, subsequently providing at least one further filler and/or pigment and combining the gel with the at least one further filler and/or pigment.

1 - 17 . (canceled) 
     
     
         18 . A process for the production of composite materials comprising nano-fibrillar cellulose gels from recycled and/or deinked pulp 1 , characterized by the steps of:
 (a) providing cellulose fibres in the form of recycled and/or deinked pulp;   (b) providing at least one filler, wherein the filler of step (b) consists of particles having a median particle size of from 0.5 to 4 μm;   (c) combining the cellulose fibres of step (a) and the at least one filler of step (b) at a weight ratio of fibres to filler on a dry weight basis of from 1:33 to 10:1 by adding the fibres and at least one filler entirely or in portions before or during the fibrillating step (d);   d) fibrillating the cellulose fibres in an aqueous environment in the presence of the at least one filler from step (c) until a nano-fibrillar cellulose gel is formed, wherein the formation of the gel is verified by monitoring the viscosity of the mixture in dependence of the shearing rate, wherein the viscosity decrease of the mixture upon step-wise increase of the shearing rate is stronger than the corresponding viscosity increase upon subsequent step-wise reduction of the shearing rate over at least part of the shear rate range as shearing approaches zero;   e) providing at least one further filler, wherein the at least one further filler from step (e) consists of particles having a median particle size of from 0.01 to 15 μm; and   f) combining the nano-fibrillar gel obtained in step (d) with the at least one further filler from step (e), wherein the combination of the gel and the at least one further filler from step (e) is subjected to dewatering to obtain a compacted composite material.   
     
     
         19 . The process according to  claim 18 , wherein the cellulose fibres of step (a) are provided in the form of a suspension. 
     
     
         20 . The process according to  claim 18 , wherein the cellulose fibres of step (a) are provided in the form of a suspension at a solids content of from 0.2 to 35 wt %. 
     
     
         21 . The process according to  claim 18 , wherein the cellulose fibres of step (a) are provided in the form of a suspension at a solids content of from 1 to 4 wt %. 
     
     
         22 . The process according to  claim 18 , wherein the filler of step (b) and step (e) are independently selected from the group consisting of precipitated calcium carbonate (PCC), natural ground calcium carbonate (GCC), surface modified calcium carbonate, dolomite, talc, bentonite, clay, magnesite, satin white, sepiolite, huntite, diatomite, a silicate, or any mixture thereof. 
     
     
         23 . The process according to  claim 18 , wherein the filler of steps (b) and (e) are independently selected from the group consisting of precipitated calcium carbonate (PCC) having vateritic, calcitic or aragonitic crystal structure, ultrafine discrete prismatic, scalenohedral or rhombohedral precipitated calcium carbonate, natural ground calcium carbonate, marble, limestone, chalk, or any mixture thereof. 
     
     
         24 . The process according to  claim 18 , wherein the cellulose fibres are provided in the form of a suspension having a solids content of from 0.2 to 35 wt-%. 
     
     
         25 . The process according to  claim 18 , wherein the cellulose fibres are provided in the form of a suspension having a solids content of from 0.25 to 10 wt-%. 
     
     
         26 . The process according to  claim 18 , wherein the cellulose fibres are provided in the form of a suspension having a solids content of from 0.5 to 5 wt-%. 
     
     
         27 . The process according to  claim 18 , wherein the cellulose fibres are provided in the form of a suspension having a solids content of from 1 to 4 wt-%. 
     
     
         28 . The process according to  claim 18 , wherein the at least one further filler of step (e) consists of particles having a median particle size of from 0.01 to 5 μm. 
     
     
         29 . The process according to  claim 18 , wherein the at least one further filler of step (e) consists of particles having a median particle size of from 0.05 to 1.5 μm. 
     
     
         30 . The process according to  claim 18 , wherein the at least one further filler of step (e) consists of particles having a median particle size of from 0.1 to 0.8 μm. 
     
     
         31 . The process according to  claim 18 , wherein the filler of steps (b) and/or (e) is associated with dispersing agents selected from homopolymers or copolymers of polycarboxylic acids and/or their salts or derivatives or esters thereof; ester based on acrylic acid, methyacryloic acid, maleic acid, fumaric acid itaconic acid; acryl amide, or acrylic acid esters, methylmethacrylate or any mixtures thereof; alkali polyphosphates, phosphonic-, citric- and tartaric acids and the salts or esters thereof; or mixture thereof. 
     
     
         32 . The process according to  claim 18 , wherein the combination of fibres and of at least one filler of step (b) is carried out by adding the filler to the fibres, or the fibres to the filler and/or pigment, in one or several steps. 
     
     
         33 . The process according to  claim 18 , wherein the weight ratio of fibres to filler in step (c) on a dry weight basis is from 1:10 to 7:1. 
     
     
         34 . The process according to  claim 18 , wherein the weight ratio of fibres to filler in step (c) on a dry weight basis is from 1:2 to 2:1. 
     
     
         35 . The process according to  claim 18 , wherein the fibrillating is carried out with a homogenizer or a friction grinder. 
     
     
         36 . The process according to  claim 18 , wherein the weight ratio of fibres from step (a) to filler of step (e) on a dry weight basis is from 1:3 to 9:1. 
     
     
         37 . The process according to  claim 18 , wherein the weight ratio of fibres from step (a) to filler of step (e) on a dry weight basis is from 1:2 to 3:1. 
     
     
         38 . The process according to  claim 18 , wherein the total content of filler of steps (b) and (e) on a dry weight basis of the composite material is from 10 wt-% to 95 wt-%. 
     
     
         39 . The process according to  claim 18 , wherein the total content of filler of steps (b) and (e) on a dry weight basis of the composite material is from 20 wt-% to 75 wt-%. 
     
     
         40 . The process according to  claim 18 , wherein the total content of filler of steps (b) and (e) on a dry weight basis of the composite material is from 25 wt-% to 67 wt-%. 
     
     
         41 . The process according to  claim 18 , wherein the total content of filler of steps (b) and (e) on a dry weight basis of the composite material is from 33 wt-% to 50 wt-%. 
     
     
         42 . A composite material obtained by the process according to  claim 18 . 
     
     
         43 . A composite material obtained by a process for the production of composite materials comprising nano-finrillar cellulose gels, characterized by the steps of:
 a) providing cellulose fibres;   b) providing at least one filler and/or pigment;   c) combining the cellulose fibres of step a) and the at least one filler and/or pigment of step b);   d) fibrillating the cellulose fibres in the presence of the at least one filler and/or pigment until a gel is formed;   e) providing at least one further filler and/or pigment;   f) combining the gel of step d) with the at least one further filler and/or pigment of step e).   
     
     
         44 . The composite material according to  claim 43 , characterized in that the combination of step f) is dewatered in dewatering step g). 
     
     
         45 . A construction material comprising the composite material of  claim 42 . 
     
     
         46 . A construction material comprising the composite material of  claim 43 . 
     
     
         47 . A construction material comprising the composite material of  claim 44 . 
     
     
         48 . A packaging material comprising the composite material of  claim 42 . 
     
     
         49 . A packaging material comprising the composite material of  claim 43 . 
     
     
         50 . A packaging material comprising the composite material of  claim 44 .