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Method of treating cellulose fibers and products obtained thereby

a technology applied in the field of cellulose fibers and products obtained thereby, can solve the problems of reducing the strength properties of towels and capillaries, loosing wettability properties with time, and reducing wettability properties, so as to prevent/slow down the ageing process of cellulose fibers and increase economic and environmental demands.

Inactive Publication Date: 2002-07-25
SCA HYGIENE PROD AB
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0014] It is an object of the invention to provide a method for reducing the level of, or substantially removing, wood extractives imparting--due to ageing--a decreased absorption rate from cellulose fibers comprising contacting the fibers with a supercritical or near supercritical fluid to extract the wood extractives and removing the extract from the fibers so as to obtain improved cellulose fibers with a reduced content of extractives which impart decreased absorption rate. The use of such a method during manufacturing of cellulose fibers, or an absorbent product containing cellulose fibers, will prevent or slow down ageing processes and lead to an increased quality of the cellulose fibers or the product thereof, especially with respect to increased absorption properties such as, e.g., an increased absorption rate of a liquid to the cellulose fibers or to a product comprising cellulose fibers due to the removal of the ageing substances in an early phase.
[0052] In a further aspect, the present invention refers to a stratified absorbent product such as tissue or nonwoven based on the above extracted cellulose fibers. The stratified absorbent product of the invention comprises at least one outer layer and at least possibly one middle layer, at least one of the outer layers having at least about 10%, or at least about 30% or at least about 50%, by weight, of the dried sheet of the extracted cellulose fibers. By such an absorbent product it is possible to reduce costs and at the same time provide a product having good absorption properties, such as a high absorption rate.

Problems solved by technology

The disadvantage of using an absorption booster is that in general it is regarded as leading to a decrease in the strength properties of the towel and the capillary pressure of the fibrous web.
Another disadvantage with absorption boosters like, e.g., surfactants, is that they tend to loose their wettability property with time.
The result is that the wettability properties decrease.
As a result the surface tension is reduced which in turn leads to a decrease in the absorption properties and the tissue product becomes less wettable.
However, the use of DCM is not altogether harmless since it contains chlorine and should for this reason be avoided.

Method used

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  • Method of treating cellulose fibers and products obtained thereby
  • Method of treating cellulose fibers and products obtained thereby
  • Method of treating cellulose fibers and products obtained thereby

Examples

Experimental program
Comparison scheme
Effect test

example 1

Supercritical Fluid (SF) Extraction of Pulp

[0057] This example describes, without limiting the invention, the extraction of pulp with CO.sub.2 as the supercritical fluid.

[0058] Definition

[0059] Wood extractives are defined as the amount of material, which can be extracted from a virgin fiber pulp sample with neutral organic solvents (e.g., hexane, dichloromethane). The method described within this example illustrates a procedure to extract such components by means of supercritical carbon dioxide being as efficient as conventional solvent extraction methods.

[0060] Principle

[0061] The pulp sample is homogenized and packed into a sample cartridge. The cartridge is placed in the extractor (1) in the sample cell (2) where it is extracted by carbon dioxide at a specific temperature and pressure. The resulting extract is trapped and collected in a vial (6) filled with dichloromethane (DCM) (FIG. 1).

[0062] Reagents

[0063] Carbon dioxide, CO.sub.2 (Air Liquide, SFC quality) pressurised with 1...

example 2

[0078] Comparison of Supercritical CO.sub.2 Extraction and Solvent Extraction With Dichloromethane.

[0079] This example is a comparison between super critical CO.sub.3 extraction and solvent extraction with dichloromethane (DCM) of different pulp materials. For the DCM extraction a standard method (SCAN C 7:62) was used where the pulp is refluxed with DCM in a soxhlet apparatus for six hours followed by a graviometric determination of the extract content.

[0080] The pulp samples are prepared according to the invention with the method described in Example 1. The total extract content and the composition of the extractives in the extracts are shown in FIG. 3.

[0081] From the results shown in FIG. 3a, it appears that the SF-CO.sub.2 extraction is as effective as the solvent extraction with respect to the total extract content. From FIG. 3b it appears that certain compositions are preferably extracted with SF-CO.sub.2 compared to the conventional method using DCM. In particular, the low le...

example 3

[0084] Measurement of Absorption Rate Before and After Extraction With CO.sub.2

[0085] This example describes the absorption rate in sheets prepared from extracted or unextracted sulphite pulp.

[0086] Definition

[0087] Absorption rate is the mean velocity with which a liquid drop of a defined volume is fully absorbed into a paper sheet. The mean velocity is calculated in that the defined volume is divided by the time needed for the liquid drop of the defined volume to be fully absorbed into the paper. The absorption time needed is dependent on both the wettability, i.e., surface chemistry and the basis weight, i.e., network structure of the cellulose fibers used.

[0088] Principle

[0089] A tissue sheet made from a dynamic sheet former called Formette was used in a lab scale equipment for the manufacturing of Formette sheets. The absorption was measured using a high-speed video system.

[0090] Material

[0091] Extraction of sulphite pulp as in Example 1. Fibers were extracted twice, but no sig...

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Abstract

A method for reducing the level of or removing wood extractives from cellulose fibers and products having cellulose fibers, by the use of a supercritical or near supercritical fluid in order to increase the absorption rate of such cellulose fibers and products having cellulose fibers. Also disclosed are cellulose fibers and products having cellulose fibers, such as cellulose tissue paper, sanitary napkin or towel, nonwoven industrial wipes, baby diaper, incontinence garments, or pulp having improved qualities, such as improved absorption rate.

Description

[0001] The present application claims the priority of EP 00850190.0, filed at the European Patent Office on Nov. 10, 2000, and claims the benefit of U.S. Provisional Application, serial No. 60 / 247,056, filed in the United States on Nov. 13, 2000. The entire contents of EP 00850190.0 and U.S. Provisional Application, serial No. 60 / 247,056, are incorporated herein by reference.[0002] 1. Technical Field[0003] The present invention relates to a method using a supercritical or near supercritical fluid for removal of wood extractives from cellulose fibers and products comprising cellulose fibers to improve the qualities thereof. The present invention further relates to cellulose fibers and products comprising cellulose fibers having improved qualities.[0004] 2. Description of Related Art[0005] Kitchen towels and household towels are products which should have good wetting and absorption properties such as absorption rate and absorption capacity, especially with respect to absorption of a ...

Claims

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Application Information

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IPC IPC(8): D21C9/08D21H27/30
CPCD21C9/08D21H27/30
Inventor LINDSTROM, EVAEICHHORN, STEPHANSANDBERG, SUSSANCHIHANI, THAMI
Owner SCA HYGIENE PROD AB
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