The present invention relates to a material layer of either wet- or dry-laid soft paper, including mixtures of polymer and cellulose fibres, fibre fabric or polymer film, the layer being intended for use as a separate layer, or at least in one layer, loosely laid on, or bonded to one or more material layers or webs such as to achieve the controlled diffusion of liquid deposited on at least this separate layer or web, or such as to be a part of a bulkier and thicker material layer or web, the invention also relating to a method of manufacturing the material layer.
A laminate including soft paper in one or more layers is usually the basic material on the market today for table covers, napkins, cleaning rags, face-flannels, bibs, underpant protectors, sanitary towels, absorption products or other table and hygiene products, as well as materials used in the packaging industry. A problem with these known laminates has been that hardly any of them is able to equal, as far as possible, a woven material with characteristics of flexibility and drapability. In addition, the materials used for absorption and in particular such laminates that are used for absorbing body liquids, have limited capacity for controlled diffusion of liquid deposited on them, resulting in that the absorption layer is not optionally utilized.
The object of the present invention is to provide a material layer of the kind mentioned in the introduction, and comprising a quality-determining, flexible material which is able to provide a laminate with a controlled diffusion capacity on the one hand and on the other hand a laminate with bulk.
With the first-mentioned ability of the inventive material layer there is achieved controlled diffusion, at least over the layer, of a liquid deposited thereon, whereby practically optimum utilization of the material absorption capacity may be reached. To this end, the layer is provided with a plurality of slit formations extending over it, laterally in optionally spaced relationship such as to form separate strip formations. These strip formations may be laterally in greater or less spaced relationship, depending on the field of use. In the case where mutual spacing is small and the layer is laminated against a material web with the propensity of being a liquid barrier, effective diffusion of liquid deposited on the layer is effected in the longitudinal direction of the strip formations. This is particularly suitable when the layer is used as a material layer in diapers, sanitary towels or underpant protectors, and with absorption products in general, where controlled diffusion of a liquid deposited on the layer is desirable. The slits may be made with an orientation on the layer according to the functional requirements, i.e. in any attitude from longitudinally to transverse the layer. The slit formations may either be continuous along the entire layer in some suitable direction, or may consist of a plurality of discontinuous slits, between which are formed longitudinal, free-cut strips of the web. If the inventive layer is made up using a less strongly absorbent or diffusive fibre quality, only limited absorption or diffusion takes place in the layer itself, and thus the deposited liquid migrates in the longitudinal direction of the strip formations and in the spaces between the strip formations, while absorption then also occurs on the material webs laminated to the upper or lower faces of the layer.
A method of producing a material layer in accordance with the invention consists of cutting or stamping slits in different patterns in a material, e.g. soft paper, although material having other characteristics and compositions may be used. The slitted layer may be subsequently drawn apart such as to afford different covering percentages of the material surface and to the extent appropriate to the field of use to which the layer is put. It may then be positionally fixed by laminating against one or more adjacent material layers or webs.
In utilizing the other ability of the material layer in accordance with the invention it is placed interiorly in a laminate in combination with other material layers or webs included in the laminate. Since greater bulk is desired here, the layer is drawn apart as in the previous case, causing reticulations to be formed where the slits are, with the strip portions becoming warped as the reticulations are formed. The reticulations may also be filled with foam. The reticulate layer may have a colour differing from the other material webs included in the laminate, and several reticulate layers may be put together in different patterns or be provided with different fillers to obtain such as greater weight, softness, colouring, workability, embossing properties, and absorption capacity. In addition, the laminate containing the inventive reticulate layer can provide a thicker material of a lower weight than would otherwise be possible, and as a result the layer also affords the possibility of liquid being absorbed into the material better. There is also less material needed in the laminate containing the inventive, reticulate layer.
In an alternate embodiment of the invention, the material layer is drawn out so as to be reticulated, causing the strip configurations to become warped, and then cured or xe2x80x9cfrozenxe2x80x9d in this condition with the object of forming a bulky material layer.