Embossed multi-ply tissue product
The present invention provides a method of producing a decorative tissue product, while controlling tensile degradation in a predicable fashion. The foregoing properties may be achieved using differential depth embossing in conjunction with an embossing pattern having particular characteristics. The use of an engraved roll, such as an embossing roll, having protuberances of differing depths and patterns not only improves the properties and characteristics of the fibrous structure, but may also be used to impart a unique pattern that provides the product with a distinctive look and is appealing to consumers. Generally the unique pattern results from a first set of protuberances having a first height and defining a first pattern and a second set of embossing elements having a second height and defining a second pattern, where the first height is greater than the second height.
1. A method for embossing a fibrous structure having a plurality of fibrous web layers comprising the steps of:
a. providing a first and a second fibrous material web;
b. providing an engraved roll having a first axis of rotation, the engraved roll comprising a plurality of first embossing elements extending radially therefrom and forming a first embossing pattern and a plurality of second embossing elements extending radially therefrom, wherein the first elements have a greater radial height than the second elements;
c. providing an impression roll having a second axis of rotation and comprising a resilient surface engaging the at least one first elements of the engraved roll so as to form a first nip there-between as the engraved roll and the impression roll rotate relative to each other so as to bring the at least one first element into engagement with the resilient surface;
d. passing the first fibrous web through the first nip;
e. pressing the first web between the first and second elements and the resilient surface of the impression roll as the first web passes through the first nip wherein pressing the first web between the first elements and the resilient surface of the impression roll forms a first embossing pattern on the first web and wherein pressing the first web between the second elements and the resilient surface of the impression roll deforms the resilient surface of the impression roll such that the first web is impressed but does not impart a second embossing pattern with a lasting embossment on the first web;
f. providing a marrying roll having a third axis of rotation and having a surface engaging the at least one first element of the first roll so as to form a second nip there-between; and
g. passing the first and the second webs through the second nip thereby forming a two-ply fibrous product having a first embossing pattern.
2. The method of claim 1 wherein the radial height of the first element is at least about 15 percent greater than the radial height of the second element.
3. The method of claim 1 wherein the radial height of the first element is from about 1.35 to about 1.45 mm and the radial height of the second element is from about 0.95 to about 1.20 mm.
4. The method of claim 1 wherein the first element maintains contact with and deforms the resilient surface of the impression roll such that the intervening web is the first embossing pattern on the first web an embossment having a depth greater than about 0.5 mm.
5. The method of claim 1 wherein the impression roll comprises a rubber roll having a hardness greater than about 40 Shore (A).
6. The method of claim 1 wherein the second web is unembossed.
7. The method of claim 1 wherein the first embossing pattern comprises spaced apart linear elements defining discrete land areas there-between and the second embossing pattern comprises a plurality of discrete protuberances or a plurality of linear elements disposed within the land areas.
8. The method of claim 7 wherein the discrete land areas are substantially surrounded by the linear elements.
9. The method of claim 7 wherein the portion of the web contacted by the land area is unembossed.
10. A method of reducing the tensile strength of a multi-ply fibrous structure comprising the steps of:
a. providing a first and a second fibrous material web;
b. providing an engraved roll having a first axis of rotation, the engraved roll comprising a plurality of first embossing elements extending radially therefrom and forming a first embossing pattern and a plurality of second embossing elements extending radially therefrom, wherein the first elements have a greater radial height than the second elements;
c. providing an impression roll having a second axis of rotation and comprising a resilient surface engaging the at least one first elements of the engraved roll so as to form a first nip there-between as the engraved roll and the impression roll rotate relative to each other so as to bring the at least one first element into engagement with the resilient surface;
d. passing the first fibrous web through the first nip;
e. pressing the first web between the first and second elements and the resilient surface of the impression roll as the first web passes through the first nip wherein pressing the first web between the first elements and the resilient surface of the impression roll forms a first embossing pattern on the first web and wherein pressing the first web between the second elements and the resilient surface of the impression roll deforms the resilient surface of the impression roll such that the first web is impressed but does not impart a second embossing pattern with a lasting embossment on the first web;
f. providing a marrying roll having a third axis of rotation and having a surface engaging the at least one first element of the first roll so as to form a second nip there-between; and
g. passing the first and the second webs through the second nip thereby forming a two-ply fibrous product having a first embossing pattern; wherein the geometric mean tensile strength (GMT) of the two-ply fibrous product is at least about 20 percent less than a substantially identical unembossed two-ply fibrous product.
11. The method of claim 10 wherein the radial height of the first element is at least about 15 percent greater than the radial height of the second element.
12. The method of claim 10 wherein the radial height of the first element is from about 1.35 to about 1.45 mm and the radial height of the second element is from about 0.95 to about 1.20 mm.
13. The method of claim 10 wherein the first element maintains contact with and deforms the resilient surface of the impression roll such that the intervening web is the a first embossing pattern on the first web having a depth greater than about 0.5 mm a second embossing pattern on the first web.
14. The method of claim 10 wherein the first embossing pattern comprises spaced apart linear elements defining discrete land areas there-between and the second embossing pattern comprises a plurality of discrete protuberances or a plurality of linear elements disposed within the land areas.