CA2071290A1

CA2071290A1 - A method to obtain white cellulose from palm leaves

Info

Publication number: CA2071290A1
Application number: CA 2071290
Authority: CA
Inventors: Isaac P. Lorencez Vazquez; Carlos M. Lorencez Gonzalez
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-06-15
Filing date: 1992-06-15
Publication date: 1993-12-16

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.

Description

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.

-..

~ , , .

20712~0 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.

Claims

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.