Absorbent structure

Abstract

The present invention relates to an absorbent structure, preferably for use in absorbent products, such as used in the food, consumer, household, building and construction, beauty and medical industry, and as used in the personal hygiene industry. The substantially cellulose free absorbent structures continuously immobilise absorbent polymer material via initial smaller pockets and subsequently larger compartments allowing excellent fluid management of the absorbent polymer material in dry, partially and fully liquid loaded state. Preferably such absorbent structure volume increases are result of temporary secondary attachment patterns made in combination with substantially permanent primary attachment grids allowing the release of bigger volumes from the initial smaller volumes by detachment of the secondary attachments. Furthermore the absorbent structure according to an embodiment of the invention non-homogeneously swells to form a liquid-managing surface structure as a result of exposing the absorbent structure to liquid. The present invention foresees in the need for improved flexible, thin, lightweight absorbent structures which overcome the absorbency problems of the prior art during absorption, distribution and retention of liquids with optimal fit.

Description

FIELD OF THE INVENTION[0001]The present invention relates to an absorbent structure having a high concentration of absorbent polymer material within an integrated fluid management system, preferably for use in an absorbent product, such as for example used in the food industry (e.g. coffee pads), the consumer industry (e.g. disposable body warmers), the household industry (e.g. sheet formed detergent articles), building and construction (e.g. filter materials and insulation), beauty and medical industry (e.g. make-up pads, anti-septic wads) and absorbent articles as used in the personal hygiene industry (e.g. feminine hygiene garments, baby diapers and pants, adult incontinence garments). The present invention also relates to an absorbent article comprising such absorbent structure and to a method and apparatus for manufacturing such absorbent structure.BACKGROUND OF THE INVENTION[0002]Disposable absorbent articles have an absorbent structure for absorbing bodily exudates, a soft li...

AI Technical Summary

Benefits of technology

The inventor found that creating absorbent structures with small cellsulose-free pockets that immobilize absorbent polymer materials in their dry state and allow them to swell non-homogenously in their wet state is effective in managing fluid and providing both internal and external management surfaces. The structures can contain particulate material and can be attached using ultrasonic bonding, thermo-bonding, pressure-bonding, or glue-bonding means. The absence of synthetic immobilization admixtures makes the structure environmentally and economically friendly. The patent text is about a new method for creating absorbent structures that efficiently manage fluid and have improved performance.

Problems solved by technology

These fibrous substances make these absorbent articles typically quite fluffy and bulky.

Some of these absorbent articles may be better at storing liquid, however they are not necessarily good at absorbing and distributing liquid when the absorbent article is actually being used.

Failing to provide sufficient structural integrity results in loss of functional performance characteristics such as coherence, absorption, distribution and / or retention and results in failures related but not limited to for instance leakages, high rewet values, etc.

On the other hand however the presence of this physical and / or chemical interaction in between the absorbent material and the restraining material often also leads to a reduced absorption, distribution and / or retention performance.

The larger proportion of absorbent polymer materials and related immobilisation requirements in substantially cellulose free absorbent articles may thus greatly inhibit the absorption, distribution and / or retention of liquids if inadequately managed.

Certainly decreased absorption speed and fluid distribution are common causes of failure.

Especially when absorbent polymer material concentrations are absolutely or relatively high and wetted, the hydro-gel can block the initial and / or additional fluid from reaching other still more absorbent regions of the absorbent core, thus leading to unappreciated, underused or unused absorbent capacity.

The diminished capacity results in leakages, well before the absorbent core is fully saturated.

Also the structural volume restrictions of these absorbent structures lead to a further reduced absorbent performance due to limited swelling capacity of the absorbent polymer material increasing the tendency to functional failures and leakages.

To remedy, absorbent article designers have and typically use additional side cuffs and acquisition layers which are expensive, inefficient and can only partly remedy these limitations.

By not completely abandoning the use of hydrophilic fibrous materials next to the use of absorbent polymer materials this problem can be partially resolved, however, it will be clear that in such case the absolute and relative proportions of absorbent materials will unwillingly be restricted and thus any thickness reduction of the absorbent structure not fully optimised.

While this construction may provide good immobilisation of the absorbent polymer material in the dry state, it seems that only a lesser immobilisation can be achieved in the liquid loaded state.

Therefore, in particular when the absorbent structure is to be used in an absorbent article to absorb and retain high amounts of bodily exudates, for example a diaper or pants, the absorbent structure disclosed herein may not be fully satisfactory.

Furthermore the fibrous bulk material increases thickness and weight, reduces flexibility and raises the cost and environmental footprint of the absorbent structure which is highly unfavourable and undesirable.

By poor fluid management it is meant that the regions of absorbent polymer material have insufficient integrity in dry, partially wet and / or wetted state.

This results in the physical continuity (and thus the capability of acquiring and transporting fluids through interstitial voids and capillaries) of the hydrogel formed upon swelling in the presence of fluids being substantially disrupted and altered, leading to the hydrogel layers being unintentionally separated, having gaps being introduced, having areas that are significantly thinned and / or broken up into a plurality of underperforming segments.

Obviously this minimizing or completely negating coherence, permeability and flow conductivity properties of the absorbent structure results in highly undesirable performance and unacceptable product failure.

However, in order to adequately secure the absorbent material, one needs to use a significant amount of thermoplastic material, which obviously leads to much higher costs and unappreciated stiffness and rigidity, thereby reducing good product fit, comfort and discreetness.

Furthermore the very high quantities of thermoplastic material lead to physical and chemical shielding of the absorbent polymer materials from the fluids, leading to unavoidable reduced absorption, distribution and retention performance and importantly due to their single use put forward a significant burden on society, industry and families from economic, environmental and sustainability view.

Therefore, such absorbent structures are considered to be unfavourable.

Whilst the above attempts describe various approaches to various problems, it is believed that none of these absorbent structures leads to very favourable and performing absorbent structures or articles.

The inefficient use of the absorbent material capacity and complex manufacturing processes makes neither of the above absorbent articles economically, technically and / or environmentally advantageous.

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