Stock material or miscellaneous articles – Structurally defined web or sheet – Continuous and nonuniform or irregular surface on layer or...
Patent
1997-01-14
1998-12-08
Loney, Donald
Stock material or miscellaneous articles
Structurally defined web or sheet
Continuous and nonuniform or irregular surface on layer or...
428166, 428172, 428198, 428212, 156209, 156290, 156292, D06N 704, B32B 300
Patent
active
058466363
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention concerns the field of absorbent papers for household and sanitary use and its object is a multi-layer sheets for such products as toilet paper, handkerchiefs, napkins or paper towels, as well as its manufacturing method.
BACKGROUND OF THE INVENTION
To manufacture household and sanitary papers, the industry uses low-weight, absorbent and creped paper such as cellulose wadding, i.e., tissue paper. Creping imparts bulk to the sheet and results in improved liquid absorption, touch and softness.
To increase absorption, multi-layer sheets have been made, namely, by combining two or more plies.
Illustratively, U.S. Pat. No. 3,867,225 describes a process for manufacturing such a product and consists in separately embossing two plies of tissue paper into a pattern of protrusions at the rate of 2 to 30/cm.sup.2, in applying an adhesive to the tips of some of these protrusions, in bringing close the embossed sides of the two plies (that is the sides having the protrusions) by arranging the protrusions of one side between those of the other side, and in adhesively bonding the tips of one ply to the troughs of the other ply. On account of the voids subtended between the two plies, a structure is achieved which has improved absorption over the absorbing sheets lacking this processing. In some product applications wherein softness is an important criterion, an excessive number of bonding spots between the two plies is undesirable since the total bonded area proportional to the number of such spots results in significant rigidity. Glue deposition is implemented by a glue depositing cylinder and thereby the number of bonding spots is equal to the number of protrusions of the glue-receiving ply. To lower this number of bonding spots, this patent proposes partial glue deposition by using a glue depositing cylinder of which the surface is hollowed by alveoles. Regrettably, such a solution was found to be industrially impractical because it led to rapid cylinder fouling by material accumulating in the alveoles.
U.S. Pat. No. 4,320,162 describes a multi-layer sheet composed of two embossed plies. Each ply comprises a wide pattern of first and relatively deep embossed protrusions surrounded by a more tightly arrayed pattern of more shallowly embossed second protrusions. In a first embodiment, the two plies are combined by means of the tips of the first protrusions and, in a second embodiment, by the tips of the first protrusions of a first ply and by the tips of the second protrusions of the second ply. Theoretically, such a configuration offers more inner volume than the design of U.S. Pat. No. 3,867,225 because the two plies are joined together by the tips of the protrusions. However, such a sheet is less crush-resistant, and already at low pressure, the protrusions are observed to sag.
OBJECTS AND BRIEF DESCRIPTION OF THE INVENTION
The object of the present invention is a multi-layer structure combining the advantages of the two procedures above while avoiding the drawbacks, and further the manufacturing method for the multi-layer structure.
The object of the invention is an absorbing multi-layer sheet having at least two layers each composed of at least one creped absorbing paper ply with a specific surface-weight of 10 to 40 g/m.sup.2, having an external surface forming the outside of the multi-layer sheet and an inner surface. The inner surface of the first layer comprises first and second protrusions and the inner surface of the second layer comprises third protrusions nested between the protrusions of the first layer. The two layers are bonded to each other at least by some of the tips of one layer that are adhesively affixed to the other layer between two protrusions. This multi-layer sheet is characterized in that the joining or bonding is implemented by the first protrusions of the first layer, the second protrusions evince a lesser height than the first one and their tips are free of adhesive.
The invention offers a less rigid sheet than a sheet with the same number
REFERENCES:
patent: 4307141 (1981-12-01), Walburn
patent: 4320162 (1982-03-01), Schulz
patent: 4483728 (1984-11-01), Bauernfeind
Hungler Joel
Laurent Pierre
Ruppel Remy
Fort James France
Loney Donald
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