Single layer papermakers fabric
A single layer papermakers fabric comprises machine direction (MD) warp yarns interwoven with cross-machine direction (CD) weft yarns to a repeating weave pattern requiring N sheds in the loom, N being an integer and at least 4. Each warp yarn follows a path in the paper side surface comprising four segments in each pattern repeat. In each of the first and third segments, the warp yarn interweaves with three consecutive weft yarns to form a double warp knuckle, and in the second and fourth segments, the warp yarn forms respectively a first and second MD float having unequal float lengths, at least one of the MD floats being over at least N consecutive weft yarns. The fabrics provide high air permeability, and increased surface contact area, stability and seam strength, and are particularly suitable for use as forming fabrics and through air dryer fabrics for tissue and towel products.
1. A single layer papermakers fabric having a paper side surface and a machine side surface and comprising machine direction (MD) warp yarns interwoven with cross-machine direction (CD) weft yarns to a repeating weave pattern requiring N sheds in the loom, wherein N is an integer and is at least 4, and wherein the warp yarns follow paths in the paper side surface comprising in each repeat for each warp yarn a first, second, third and fourth segment, wherein
(i) in each of the first and third segments, the warp yarn interweaves with a first and second group of weft yarns each comprising three consecutive weft yarns at respective first and second interweaving locations to form a double warp knuckle; and
(ii) in the second and fourth segments, the warp yarn forms respectively a first and second MD float having unequal float lengths wherein at least one of the MD floats is over at least N consecutive weft yarns.
2. A single layer papermakers fabric as claimed in claim 1 wherein the repeating weave pattern is selected from an N×2N pattern and an N×4N pattern.
3. A single layer papermakers fabric as claimed in claim 1 wherein for each warp yarn each of the first and second MD floats is over at least N consecutive weft yarns.
4. A single layer papermakers fabric as claimed in claim 1 wherein N is selected from 4, 5, 6, 8, 10, 12, 16, 20 and 24.
5. A single layer papermakers fabric as claimed in claim 1 wherein for each warp yarn the interweaving locations are offset from interweaving locations on each adjacent warp yarn at displacement zones each comprising at least one weft yarn.
6. A single layer papermakers fabric as claimed in claim 1 wherein all of the warp yarns comprise pairs in which each member of a pair interweaves with the same weft yarns as the other member of that pair.
7. A single layer papermakers fabric as claimed in claim 6 wherein for each warp yarn pair the interweaving locations are offset from interweaving locations on the warp yarns of each adjacent warp yarn pair by at least one weft yarn.
8. A single layer papermakers fabric as claimed in claim 1 wherein the warp yarns have a cross-sectional profile in the CD selected from substantially circular, substantially elliptical, substantially rectangular and substantially square.
9. A single layer papermakers fabric as claimed in claim 8 wherein the cross-sectional profile is substantially square.
10. A single layer papermakers fabric as claimed in claim 8 wherein the weft yarns have a weft cross-sectional area which is at least equal to a warp cross-sectional area of the warp yarns.
11. A single layer papermakers fabric as claimed in claim 10 wherein the weft cross-sectional area exceeds the warp cross-sectional area by a range between 0% and 15%.
12. A single layer papermakers fabric as claimed in claim 10 wherein the weft cross-sectional area exceeds the warp cross-sectional area by a range between 10% and 15%.
13. A single layer papermakers fabric as claimed in claim 1 wherein the fabric has an air permeability in a range of 450 to 1,200 cubic feet per minute.
14. A single layer papermakers fabric as claimed in claim 1 wherein the fabric has a mesh in a range of 20 to 70 yarns per inch.
15. A single layer papermakers fabric as claimed in claim 1 which is a through air dryer fabric.
16. A single layer papermakers fabric as claimed in claim 1 which is a forming fabric.