A METHOD TO OBTAIN WHITE CELLULOSE FROM PALM LEAVES

METHODE DE PRODUCTION DE CELLULOSE BLANCHE A PARTIR DE FEUILLES DE PALMIER

English Abstract

ABSTRACT
In the production of cellulose from trees, it is well known about the lenghty, pollutant
and expensive processes currently in use. This new industrial process to obtain high
quality cellulose from palm leaves (Copernicia Tectorum) is quicker, cleaner and eco-
nomical. It produces an excellent quality cotton-type cellulose, with an approximate con-
tent of 96% of alpha-cellulose and 4% of beta-, gamma-cellulose and residuals, from an
abundant and low priced raw material.

Claims

CLAIM
The embodiments of the invention in which an exclusive property or privilege is claimed
are defined as follows:
1.-A process to obtain cellulose, which comprises converting raw material by chemical
attacks to an excellent quality cotton-type cellulose, and obtaining lignin as a subpro-
duct.
2.-A process as defined in claim 1, in which the raw material to be processed consists
of palm leaves from Sabal Mexicana (or Copernicia Tectonum), and the first chemical
attack consists of a treatment of the minced palm leaves with a solution of sodium
hydroxide within a rotatory reactor.
3.-A process as claim in claims 1 or 2, in which the cellulose obtained after the chemi-
cal attack is repeatedly washed, filtered and compressed, before being conveyed into
the bleaching tank, where it undergoes another chemical attack with sodium
hypochlorite.
4.-A process as defined in claims 1, 2 or 3, in which after being bleached the cellulose
is washed, filtered and compressed repeatedly, before obtaining the final product.
5.-A process as defined in claim 1, in which the black liquor obtained from the rotatory
reactor is neutralized with hydrochloric acid, and the precipitated lignin is separated by
filtration.

Description

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SPECIFICATION
This invented industrial process relates to the production of cellulose form trees and
plants.
There are several other industrial processes producing cellulose from different raw
materials which involve the use of pines, sugar canes, straw, etc. These processes use
highly concentrated chemical reactants along with high temperatures and high pressures
within pressure vessels, producing residuals difficult to eliminate.
This process obtains cellulose from palm leaves, specifically, the type known asSabal Mexicana (Copernicia Tectorum). This palm is part of the vegetation of any tropical
region and because of its unrrestricted growlng, dense forests are commonly found in
Mexico, Central and Soùth America and the Antilles.
Two of the rnost important problems the paper industry is facing today are the eco-
nomical and the environmental issues. Both are vastly reduced with this process.
DESCRIPTION OF THE INDUSTRIAL PROCESS
The palm leaves are minced into 1 cm long pieces, approximately, in orderto improve
the action of the chemical reactant, which is a solution of 3.7% sodium hydroxide ~NaOH),
with 85% industrial purity.' The required amount of chemical reactant is 4.0 liters per
kilogram of palm leaves. After adding the reactant, the mixture of leaves with reactant is
stirred during 15.0 min in a mixer ~ank.
The mixture is conveyed to a reactor with rotational motion. Once the loading isfinished, the pressure within the reactor is increased to 4.0 kg/cm2 using overheated steam
and kept at this level during 2.0 hrs.2 After this, the mixture is drained into a discharge
tank and then fed to a filtering press to separate the obtained cellulose from the black
liquor. The black liquor is sent to a treatment tank.
The filtered cellulose is now compressed, and a cycle of washing, filtering and
compressing, which is repeated four times, is begun. Before the last filtering, the cellulose
is first passed through a sieve to separate the parts of leaves which were not affected by
the reactant during the cooking.
Once the fourth oycle of washing, filtering and compressing has been performed, the
cellulose is conveyed to the bleaching container. The bleaching chemical used is a solution
1 Other processes require solutions of higher concentrations of chemical reactants,
ranging from 8.0% to 12.0%.
2 Higher pressures varying from 5.0 to 8.0 kg/cm2, and longer periods, 4 to 8 hrs, are
commonly required in other processes.
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of 0.2% sodium hypochlorite (NaOCI, industrial use) and is added in the ratio of 3.0 Iiters
per kilogram of palm leaves. The mixture is stirred for 15.0 min and left resting during 12.0
hrs.3 Afterwards, the cellulose is filtered and compressed in orderto remove the bleacher.
The bleached cellulose is again washed, filtered and compressed fourtimes. Finally,
the cellulose is dried and packaged, ready to be sent to either a paper mill or a chemical
company.
The black liquor is neutralized with commercial hydrochloric acid (HCI), and theprecipitated lignin is separated by filtration. After drying and packaging, the lignin is ready
to be commercialized.
3 Alternative processes use bleaching solutions with typicai concentrations of 5.0 to
8.0%, and periods of 24 to 48 hrs.