Method for deforming a web
Methods for forming discrete deformations in web materials are disclosed. In some embodiments, the method involves feeding a web into an apparatus having nips that are formed between intermeshing rolls. The apparatus may be in the form of nested or other arrangements of multiple rolls, in which the web is maintained in substantial contact with at least one of the rolls throughout the process, and at least two of the rolls define two or more nips thereon with other rolls. In some embodiments, rolls can be used to expose a different side of the web for a subsequent deformation step. In these or other embodiments, the rolls can be used to transfer the web between rolls in such a manner that it may offset the rolls and/or web so that subsequent deformations are formed at a different cross-machine direction location than prior deformations.
1. A process for deforming a precursor web using an apparatus, wherein the precursor web has two surfaces, the process comprising:
a) feeding the precursor web in a machine direction into a first nip that is formed between a first pair of generally cylindrical mating rolls, said first pair of mating rolls comprising a first roll and a second roll, at least one of said first and second rolls having a surface with forming elements thereon, wherein when said precursor web is fed into said first nip, said precursor web is permanently deformed in a first location to form a first time deformed precursor web;
b) feeding the precursor web into a non-permanently deforming intermediate transfer nip to contact the precursor web and transfer said web to a third nip while substantially maintaining registration of the web, wherein said transfer nip is formed by two transfer nip rolls comprising a first transfer nip roll and a second transfer nip roll, and said two transfer nip rolls have a pattern of elements thereon, said elements having radially outwardmost portions, wherein the radially outwardmost portions on said first transfer nip roll substantially align with the radially outwardmost portions on said second transfer nip roll; and
c) feeding said precursor web into a third nip between a third roll and a fourth roll, wherein at least one of said third and fourth rolls has forming elements on its surface, and when said precursor web is fed into said third nip, said precursor web is deformed in a second location in which at least some of said forming elements in said third nip deform said first-time deformed precursor web at least partially in different locations than said precursor web was deformed in said first nip to form a second-time deformed precursor web,
wherein said precursor web remains substantially in contact with at least one roll at all times along the portion of its length from the location where the web enters the first nip to the location where the web exits the last nip.
2. A process for deforming a precursor web using an apparatus, wherein the precursor web has two surfaces, the process comprising:
a) feeding the precursor web in a machine direction into a first nip that is formed between a first pair of generally cylindrical mating rolls, said first pair of mating rolls comprising a first roll and a second roll, at least one of said first and second rolls having a surface with forming elements thereon, wherein when said precursor web is fed into said first nip, said precursor web is permanently deformed in a first location to form a first time deformed precursor web;
b) feeding the precursor web into a non-permanently deforming intermediate transfer nip to contact the precursor web and transfer said web to a third nip while substantially maintaining registration of the web, wherein said transfer nip is formed by two transfer nip rolls comprising a first transfer nip roll and a second transfer nip roll, and said two transfer nip rolls have a pattern of elements thereon, said elements having radially outwardmost portions, wherein the radially outwardmost portions on said first transfer nip roll are offset relative to the radially outwardmost portions on said second transfer nip roll; and
c) feeding said precursor web into a third nip between a third roll and a fourth roll, wherein at least one of said third and fourth rolls has forming elements on its surface, and when said precursor web is fed into said third nip, said precursor web is deformed in a second location in which at least some of said forming elements in said third nip deform said first-time deformed precursor web at least partially in different locations than said precursor web was deformed in said first nip to form a second-time deformed precursor web,
wherein said precursor web remains substantially in contact with at least one roll at all times along the portion of its length from the location where the web enters the first nip to the location where the web exits the last nip.
3. The process of claim 2 wherein the elements on said first transfer nip roll have a pitch therebetween and the elements on said second transfer nip roll have a pitch therebetween, and the radially outwardmost portions on said first transfer nip roll are offset relative to the radially outwardmost portions on said second transfer nip roll by a distance of about ½ the pitch between the elements on one of said first and second transfer nip rolls.
4. A process for deforming a precursor web using an apparatus, wherein the precursor web has two surfaces, the process comprising:
a) feeding the precursor web in a machine direction into a first nip that is formed between a first pair of generally cylindrical mating rolls, said first pair of mating rolls comprising a first roll and a second roll, at least one of said first and second rolls having a surface with forming elements thereon, wherein when said precursor web is fed into said first nip, said precursor web is permanently deformed in a first location to form a first time deformed precursor web;
b) feeding the precursor web into a non-permanently deforming intermediate transfer nip to contact the precursor web and transfer said web to a third nip while substantially maintaining registration of the web wherein said transfer nip comprises a first transfer nip that is formed between a pair of generally cylindrical mating rolls, wherein at least one of said rolls forming said first transfer nip has elements on its surface with radially outwardmost portions, and said process further comprises feeding the precursor web into a second transfer nip that is formed between a pair of generally cylindrical mating rolls wherein at least one of said rolls forming said second transfer nip has elements on its surface with radially outwardmost portions, and wherein said second transfer nip is disposed between said first transfer nip and said third nip to contact the precursor web and transfer said web to said third nip; and
c) feeding said precursor web into a third nip between a pair of generally cylindrical mating rolls, wherein at least one of said rolls comprising said third nip has forming elements on its surface, and when said precursor web is fed into said third nip, said precursor web is deformed in a second location in which at least some of said forming elements in said third nip deform said first-time deformed precursor web at least partially in different locations than said precursor web was deformed in said first nip to form a second-time deformed precursor web,
wherein said precursor web remains substantially in contact with at least one roll at all times along the portion of its length from the location where the web enters the first nip to the location where the web exits the third nip.
5. The process of claim 4 wherein the rolls in one of the first and second transfer nips are substantially aligned, and rolls in the other of the first and second transfer nips are offset, so that the radially outwardmost portions of the elements on the rolls in the other transfer nip are offset relative to each other in at least one of the machine direction and the cross-machine direction.