Compositions comprising microfibrillated cellulose and polymers and methods of manufacturing fibres and nonwoven materials therefrom
Fibres and nonwoven materials comprising microfibrillated cellulose, and optionally inorganic particulate material and/or additional additives, and optionally a water soluble or dispersible polymer. Nonwoven materials made from fibres comprising microfibrillated cellulose, and optionally inorganic particulate material and/or a water soluble or dispersible polymer.
1. A method for preparing a fibre consisting of (a) microfibrillated cellulose and (b) one or more calcium carbonate and/or kaolin, the method comprising the steps of:
(1) preparing a composition consisting of microfibrillated cellulose and calcium carbonate and/or kaolin, wherein the microfibrillated cellulose has a fibre steepness ranging from about 20 to about 50; wherein the microfibrillated cellulose is obtained by a two-stage process of (i) grinding a fibrous substrate comprising cellulose in a grinding vessel in the presence of the calcium carbonate and/or kaolin and (ii) refining in a refiner or homogenizing in a homogenizer; or sonicating with an ultrasonic device the ground fibrous substrate comprising cellulose and the calcium carbonate and/or kaolin; wherein the grinding is carried out in an aqueous environment in the presence or in the absence of a grinding medium; wherein the term “grinding medium” means a medium other than the calcium carbonate and/or kaolin;
(2) extruding the microfibrillated cellulose and the calcium carbonate and/or kaolin from step (1) through an extruder;
(3) attenuating the extruded microfibrillated cellulose and the calcium carbonate and/or kaolin with an attenuating gas; and
(4) collecting the extruded fibre.
2. The method of claim 1 , wherein the microfibrillated cellulose has a median diameter (d 50 ) less than 100 μm.
3. The method of claim 1 , wherein the attenuating gas is one or more streams of hot air.
4. The method of claim 1 , wherein the ultrasonic device is selected from the group consisting of an ultrasonic probe, an ultrasonic water bath, an ultrasonic homogenizer, an ultrasonic foil and an ultrasonic horn.
5. The method of claim 1 , wherein the grinding vessel is a screened grinder.
6. The method of claim 5 , wherein the screened grinder is a stirred media detritor.
7. The method of claim 1 , wherein the fibre is extruded at a temperature from about 80° C. to about 100° C.
8. The method of claim 1 , wherein the fibre has an average diameter of from about 0.1 μm to about 1 mm.
9. The method of claim 1 , wherein the fibre has an elastic modulus from about 5 GPa to about 20 GPa as determined by a tensiometer.
10. The method of claim 1 , wherein the fibre has a fibre strength of about 40 MPa to about 200 MPa as determined by a tensiometer.
11. The method of claim 1 , wherein the fibre is a spunlaid fibre.
12. The method of claim 11 , wherein the spunlaid fibre is formed by spunbonding.
13. The method of claim 1 , wherein the collecting step is deposition of the fibre onto a foraminous surface to form a non-woven web.
14. The method of claim 13 , wherein the foraminous surface is a moving screen or wire.
15. The method of claim 13 , wherein the non-woven web is bonded by hydro-entanglement.
16. The method of claim 13 , wherein the non-woven web is bonded by through-air thermal bonding.
17. The method of claim 13 , wherein the non-woven web is bonded mechanically.
18. The method of claim 1 , wherein the grinding is carried out in an aqueous environment in the presence of the grinding medium.
19. The method of claim 1 , wherein the grinding is carried out in an aqueous environment in the absence of the grinding medium.