Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Patent
1992-05-05
1996-02-20
Ryan, Patrick J.
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
428357, 428373, 428379, 428342, 536 56, 604350, 604360, 604375, 604904, D02G 300
Patent
active
054927595
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the field of absorption material, and particularly to absorption material for use in the manufacture of sanitary articles such as diapers, incontinence guards, drying cloths and the like, the absorbent material of such articles containing fibres of enlarged specific surface area and therewith a high absorption rate. The invention also relates to a method of manufacturing these fibres, their use in the form of fluff pulp or in mixture with untreated fibres in the form of fluff pulp, in order to obtain improved absorption.
One generally known problem within the field of the manufacture of absorbent material for use, preferably in the production of sanitary articles, such as diapers, incontinence guards, etc., resides in the achievement of optimum absorption rates and dispersion or distribution properties with respect to the absorption and dispersion of liquid in the fibre material of the fluff pulp.
Our earlier filed Swedish Patent Application No. 8903180-1. from which convention priority is requested for the present Patent Application, describes a method of treating cellulose fibres intended for absorption purposes, wherein the absorption properties of a cellulose-based fibre material are improved by precipitating silicate onto the fibre walls in situ, this precipitation being effected in a two-stage process. In the first of these stages, the fibres are impregnated with an alkali silicate and, after being dewatered, the fibres are treated with an aluminium salt solution, subsequent to adjusting the pH to a value of at most 9. This treatment results in the precipitation of silicate onto the fibre walls, which improves liquid transportation and liquid retention, and also prevents swelling collapse when drying.
Our Swedish Patent Application 9002475-3 (our reference No. 20677) filed simultaneously with the present application describes fibres treated with an aluminium salt solution, these fibres also resulting in a material of increased absorption rate without the addition of silicate, even though the presence of silicate affords some further improvement. The treatment is carried out at given pH-ranges, namely at pH=5-11, preferably pH=8.5-9.5, particulary at pH=9.
Thus, when applying the present invention there is obtained an increase in the specific surface area of the fibres, intended in particular as absorbent material in sanitary articles, this enlarged specific surface area resulting in a markedly improved absorption rate and liquid transport of the fibre material. Subsequent to being treated with hydrophilic chemicals, the fibre surface exhibits a relatively thin porous layer, i.e. a layer having a thickness less than 2000 .ANG..
The porous layer is obtained by treating (impregnating) the fibre material with hydrophilic chemicals, the fibres being in either a dry state or a moist state, either in the form of a dewatered fibre pulp or in the form of a fibre-water suspension. This treatment process may be effected by bringing the fibres, in one of the aforesaid states, into contact with the hydrophilic chemicals, e.g. by spraying the fibres in a dry or moist state. with a chemical solution, or by mixing the chemicals with a fibre dispersion, where the chemicals are supplied in a solid, commercially available state or in the form of a solution. This admixture or spraying process can be carried out with the aid of typical equipment used conventionally in this technique.
Other appropriate treatment conditions are conventional, and optimum conditions can be readily established by the person skilled in this art, e.g. conditions concerning pH, temperature, mixing speed, chemical quantities, impregnation times, etc.
The interaction between fibres and precipitation chemicals can be achieved in a number of ways. Van der Waals interaction and/or electrostatic interaction (including, inter alia, adsorption of precipitation chemicals on the fibre surface) exist between fibres and precipitation chemicals. Furthermore, flocculation/precipitation takes place alone or in combination with
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patent: 2762822 (1954-03-01), Vagemius
patent: 2856330 (1958-10-01), Vagemius
patent: 3172817 (1965-03-01), Leupold et al.
patent: 3932209 (1976-01-01), Chatterjee
patent: 4385632 (1983-05-01), Odelhog
patent: 5104411 (1992-04-01), Makoui et al.
Annergren Goran E.
Eriksson Inger V.
Wagberg Lars E. R.
Dixon Merrill
Molnlycke AB
Ryan Patrick J.
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