Paper making and fiber liberation – Processes of chemical liberation – recovery or purification... – Mechanical defibration of logs or blocks after chemical...
Patent
1997-07-16
1999-10-12
Nguyen, Dean T.
Paper making and fiber liberation
Processes of chemical liberation, recovery or purification...
Mechanical defibration of logs or blocks after chemical...
162 76, 162187, 426573, D21B 104
Patent
active
059649836
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention concerns a novel parenchymal cellulose and a process for its production. More particularly, the present invention concerns a novel microfibrillated cellulose and a process for its production from primary wall plant pulp, particularly from sugar beet pulp after extraction of saccharose.
Cellulose is a substance of great industrial importance which has numerous applications, including: and suspensions, for low calorie food products, low fat or low cholesterol food products, etc; cosmetics, etc; precipitation control agent, ointment or cream support, intestinal transport agent, etc.
Until now, all known celluloses have had disadvantages.
WO 93/11182 from Weyerhaeuser describes a bacterial cellulose with a reticulated structure. Apart from being very expensive, such a bacterial cellulose can cause contamination problems in alimentary applications.
FR-A-2 472 628 from ITT INDUSTRIES describes a microfibrillated cellulose essentially constituted by secondary walls obtained from wood pulp. Such a cellulose cannot easily be taken up into suspension once dehydrated. this causes considerable storage and transport problems due to the fact that the suspensions have a maximum cellulose content of about 4%.
In attempting to overcome that disadvantage, EP-A-0 120 471 from ITT INDUSTRIES describes a redispersable dried secondary wall (since it is obtained from wood pulp) microfibrillated cellulose which is characterized by the presence of an additive which prevents the formation of hydrogen bonds between the cellulose fibrils. The quantity of additive is considerable (at least 50% by weight with respect to the cellulose, and preferably at least the same quantity thereof). The additive is, for example, a polyhydroxylated compound such as a sugar containing 5 to 6 carbon atoms or a glycol, a borate or an alkaline phosphate, an aprotic solvent, an amine or a quaternary ammonium compound. Apart from the fact that the designation "cellulose" is improperly assigned to a product which is at most half cellulose, this "cellulose" is costly and is not suitable for all applications. Further, without the addition of additives this cellulose can only recover from 2% to a maximum of 20% of its initial viscosity after drying. Maintaining the viscosity requires the presence of an additive in an amount by weight which is substantially the same as that of the cellulose.
EP-A-0 102 829 from Weibel describes a process for simultaneously isolating the cellulosic and hemicellulosic constituents of sugar beet pulp. However, as with FR-A-2 472 628 cited above, once dehydrated, the parenchymal cellulose obtained cannot readily be taken up again into suspension, causing the same storage and transport problems.
Further, the economic exploitation of plant residues, in particular sugar beet pulp, is of great industrial importance.
One aim of the present invention is to provide a microfibrillated cellulose which can be taken up into suspension after dehydration without adding an additive.
Another aim of the invention is to provide a microfibrillated cellulose which regains almost all of its initial viscosity after drying, without adding an additive.
A further aim of the invention is to provide a process for the production of cellulose by economic exploitation of primary wall plant residues, in particular sugar beet pulp.
The present invention achieves all these three aims.
Further aims and advantages of the invention will become apparent from the description below.
THE INVENTION
In general, native cellulose is always in a microfibrillate form, these microfibrils being associated to a greater or lesser degree to form fibers, walls and membranes. Each cellulosic microfibril is constituted by a rigorous assembly of parallel cellulose chains resulting from the method by which the cellulose is biosynthesized. Cellulose microfibrils are generally considered to contain only a few faults along their axis. Their mechanical properties are close to the theoretical mechanical properties of cellulose: a tenacit
REFERENCES:
patent: 4481076 (1984-11-01), Herrick
patent: 4481077 (1984-11-01), Herrick
patent: 4649113 (1987-03-01), Gould
Chanzy Henri
Dinand Elisabeth
Maureaux Alain
Vignon Michel R.
Vincent Isabelle
General Sucriere
Nguyen Dean T.
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