Dryer fabric

Abstract

A papermaking dryer fabric has a system of MD yarns interwoven with a system of CMD yarns in a single layer weave. The MD yarns have groups each formed of a plurality of adjacent MD yarns weaving in the group side-by-side the same weave path with the CMD yarns. The dryer fabric is flat woven with seaming loops at the widthwise edges of the fabric to make it endless. At least some of the seaming loops are formed by at least some MD yarns of the groups of MD yarns. The MD yarns forming the groups of MD yarns have a circular cross section and the CMD yarns are ungrouped CMD yarns and at least some of said CMD yarns have a non-circular cross section with a width to height ratio of more than 1. The dryer fabric has an air permeability between 25 cfm and 200 cfm.

Claims

1. A papermaking dryer fabric, comprising: a system of MD yarns interwoven with a system of CMD yarns in a single layer weave; said MD yarns including groups of MD yarns, with each of said groups of MD yarns being formed by a plurality of adjacent MD yarns weaving in said group side-by-side a same weave path with said CMD yarns, said MD yarns forming said groups of MD yarns having a circular cross section; said CMD yarns being ungrouped CMD yarns and all of said CMD yarns having a non-circular cross section with a width to height ratio of more than 1, and said CMD yarns having a shape selected from the group consisting of a bone-shape and a double convex shape; at least some CMD yarns being formed of a two-phase polymeric material, with a first polymeric material that melts at a first temperature and a second polymeric material which is substantially immiscible with the first polymeric material and which melts at a second temperature which is lower than the first temperature; wherein the dryer fabric is flat woven with seaming loops arranged at widthwise edges of the fabric and formed in an endless dryer fabric, and wherein at least some of said seaming loops are formed by at least some MD yarns of said groups of MD yarns, and wherein the dryer fabric is formed to have an air permeability of between 25 cfm and 200 cfm.

2. The papermaking dryer fabric according to claim 1, wherein said single layer weave is a plain weave.

3. The papermaking dryer fabric according to claim 1, wherein all of said MD yarns form said groups of MD yarns.

4. The papermaking dryer fabric according to claim 1, wherein each said group of MD yarns is formed by four or fewer adjacent MD yarns weaving side-by-side the same weave path with said CMD yarns.

5. The papermaking dryer fabric according to claim 4, wherein each said group of MD yarns is formed by two or three MD yarns.

6. The papermaking dryer fabric according to claim 1, wherein said width to height ratio is 1.5 or more.

7. The papermaking dryer fabric according to claim 1, wherein said CMD yarns have a height of 0.5 mm or more.

8. The papermaking dryer fabric according to claim 7, wherein said CMD yarns have a height of between 0.5 mm and 1.1 mm.

9. The papermaking dryer fabric according to claim 7, wherein said CMD yarns have a height of between 0.6 mm and 1.0 mm.

10. The papermaking dryer fabric according to claim 7, wherein said CMD yarns have a height of between 0.7 mm and 0.9 mm.

11. The papermaking dryer fabric according to claim 1, wherein said MD yarns have a diameter between 0.5 mm and 0.8 mm.

12. The papermaking dryer fabric according to claim 11, wherein said MD yarns have a diameter between 0.55 mm and 0.65 mm.

13. The papermaking dryer fabric according to claim 1, wherein said air permeability of the fabric lies between 50 cfm and 200 cfm.

14. The papermaking dryer fabric according to claim 13, wherein said air permeability of the fabric lies between 50 cfm and 150 cfm.

15. The papermaking dryer fabric according to claim 1, wherein the fabric has the characteristics of having been subjected to a heat setting treatment at a temperature at or above the first temperature and below the second temperature.

16. The papermaking dryer fabric according to claim 1, wherein the fabric has two widthwise edges each provided with seaming loops formed by two MD yarns, wherein the fabric further has binder loops each being formed by two MD yarns, and wherein a binder loop is located between two adjacent seaming loops and vice versa.

17. The papermaking dryer fabric according to claim 16, wherein each of said seaming loops is formed by first and second MD yarns, and said first and second MD yarns are from the same group of MD yarns.

18. The papermaking dryer fabric according to claim 16, wherein each of said seaming loops is formed by a first MD yarn from a first group of MD yarns and by a second MD yarn from a second group of MD yarns adjacent to the first group of MD yarns.

19. The papermaking dryer fabric according to claim 1, wherein said second polymeric material is selected from the group consisting of polyolefins, polyamides, fluoropolymers and combinations thereof, and said first polymeric material includes, alone or in combination, homopolymers or copolymers of polyester.

Description

(1) The invention will be further illustrated with the following figures, wherein

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(2) FIG. 1 shows a top view onto a part of the dryer fabric according to the invention,

(3) FIG. 2 shows a cross sectional view in CMD direction of the fabric of FIG. 1,

(4) FIG. 3 shows a cross sectional view in MD direction of the fabric of FIG. 1 with CMD yarns having a rectangular cross section,

(5) FIG. 4 shows a cross sectional view in MD direction of an alternative fabric with CMD yarns having a bone-like cross section,

(6) FIG. 5 shows a cross sectional view in MD direction of an alternative fabric with CMD yarns having a double convex shaped cross section,

(7) FIG. 6 shows top view onto a part of the dryer fabric as seen in FIG. 1 with a first variant of seam loop construction and

(8) FIG. 7 shows top view onto a part of the dryer fabric as seen in FIG. 1 with a second variant of seam loop construction.

DESCRIPTION OF THE INVENTION

(9) FIG. 1 shows a top view onto a part of the dryer fabric 1 according to the invention. The fabric 1 has a system of MD yarns 2 interwoven with a system of CMD yarns 3 in a single layer weave. In the embodiment shown in the FIGS. 1-3 the system of MD yarns only consists of groups 4 of two adjacent MD yarns 3 which weave in each group 4 side-by-side the same weave path with the CMD yarns 3. The dryer fabric 1 is flat woven in a plain weave design.

(10) As can be seen from FIGS. 1 and 2 the MD yarns 2 have a circular cross section. As can be seen from FIGS. 1 and 3 all the CMD yarns 3 are ungroupedthat means adjacent CMD yarns weave different weave paths with the MD yarns 2and have a rectangular cross section with a width to height ratio of 2. The CMD yarns 3 in the embodiment as shown in FIGS. 1-3 have a height of 0.6 mm, wherein the MD yarns 2 have a diameter of 0.6 mm. The dryer fabric shown can have a air permeability between 75 cfm and 140 cfm.

(11) FIG. 4 shows a cross sectional view in MD direction of an alternative fabric with CMD yarns 3a having a bone-like cross section. The rest of the fabric of FIG. 4 is identical to fabric shown in FIGS. 1 and 2.

(12) FIG. 5 shows a cross sectional view in MD direction of an alternative fabric with CMD yarns 3b having a double convex shaped cross section. The rest of the fabric of FIG. 5 is identical to fabric shown in FIGS. 1 and 2.

(13) FIG. 6 shows top view onto a part of the dryer fabric as seen in FIG. 1 with a first variant of seam loop construction. As can be seen part of the MD yarns 2 form seaming loops 5 which are arranged at the widthwise edges of the fabric 1 to make it endless. The other part of the MD yarns 2 form so called binder loops 6 to hold the widthwise fabric edges. As can be seen between adjacent seaming loops 5 a binder loop 6 is located and vice versa. In the embodiment as seen in FIG. 6 every seaming loop 5 and every binder loop 6 is formed by MD yarns 2 of different groups 4. By way of example one of the seaming loops 5 is formed by a MD yarn 2 of group 4 and by a MD yarn 2 of group 4 and adjacent binder loop 6 is formed by a MD yarn 2 of group 4 and by a MD yarn 2 of group 4.

(14) FIG. 7 shows top view onto a part of the dryer fabric as seen in FIG. 1 with a second variant of seam loop construction. As can be seen part of the MD yarns 2 form seaming loops 5 which are arranged at the widthwise edges of the fabric 1 to make it endless. The other part of the MD yarns 2 form so called binder loops 6 to hold the widthwise fabric edges. As can be seen between adjacent seaming loops 5 a binder loop 6 is located and vice versa. In the embodiment as seen in FIG. 7 every seaming loop 5 and every binder loop 6 is formed by MD yarns 2 of the same group 4. By way of example one of the seaming loops 5 is formed by the two MD yarns 2 of group 4 and adjacent binder loop 6 is formed by the two MD yarns 2 of another group 4. To hold the widthwise fabric edges this seam construction further has an additional end yarn 7 which passes through the binder loops 6 and over or under the seaming loops 5 without passing through them.