U.S. patent number RE39,176 [Application Number 10/342,983] was granted by the patent office on 2006-07-11 for resin-impregnated belt for application on papermaking machines and in similar industrial application.
This patent grant is currently assigned to Albany International Corp.. Invention is credited to William H. Dutt.
United States Patent |
RE39,176 |
Dutt |
July 11, 2006 |
Resin-impregnated belt for application on papermaking machines and
in similar industrial application
Abstract
A resin-impregnated endless belt for a long nip press or
calender of the shoe type, or for other papermaking and
paper-processing applications, has a base fabric in the form of an
endless loop with an inner surface, an outer surface, a machine
direction and a cross-machine direction. The base fabric has
machine-direction (MD) structural elements and
cross-machine-direction (CD) structural elements in an open
structure wherein at least some of the MD structural elements and
CD structural elements are spaced apart from one another. The MD
structural elements cross the CD structural elements at a plurality
of crossing points, where they are joined to one another by
mechanical, chemical or thermo-bonding means. A coating of a first
polymeric resin is on the inner surface of the base fabric. The
first polymeric resin impregnates and renders the base fabric
impermeable to liquids, and forms a layer on the inner surface
thereof. The coating is smooth and provides the belt with a uniform
thickness. A method for manufacturing the belt, using a smooth and
polished cylindrical mandrel with a spacer ring slidably disposed
thereon, is also shown.
Inventors: |
Dutt; William H. (Wolfeboro,
NH) |
Assignee: |
Albany International Corp.
(Albany, NY)
|
Family
ID: |
25533603 |
Appl.
No.: |
10/342,983 |
Filed: |
January 15, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
08987827 |
Dec 9, 1997 |
06174825 |
Jan 16, 2001 |
|
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Current U.S.
Class: |
442/43; 442/187;
162/901; 442/3; 442/314; 442/366; 442/58; 442/50; 442/333; 442/307;
442/220; 442/203; 162/358.4 |
Current CPC
Class: |
D21F
3/0236 (20130101); D21F 3/0227 (20130101); D21F
1/0027 (20130101); Y10T 442/3179 (20150401); Y10T
442/607 (20150401); Y10T 442/198 (20150401); Y10T
442/643 (20150401); Y10T 442/463 (20150401); Y10T
442/3317 (20150401); Y10T 442/419 (20150401); Y10T
442/3049 (20150401); Y10S 162/901 (20130101); Y10T
442/103 (20150401); Y10T 442/172 (20150401); Y10T
442/184 (20150401) |
Current International
Class: |
D21F
3/02 (20060101) |
Field of
Search: |
;442/1-3,37,43,46,50,58,181,187,203,218,220,304,307,312-314,327,330,333,366
;162/358.4,901 ;428/113,114,423.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 354 743 |
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Feb 1990 |
|
EP |
|
0 534 041 |
|
Mar 1993 |
|
EP |
|
WO 88/08897 |
|
Nov 1988 |
|
WO |
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WO 95/29293 |
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Nov 1995 |
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WO |
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Other References
"Fundamentals of Composites Manufacturing Materials, Methods, and
Applications," by A.B. Strong, Society of Manufacturing Engineers,
Michigan; pp. 66-78, 1989. cited by examiner .
Fundamentals of Composites Manufacturing: Materials, Methods, and
Applications, Society of Manufacturing Engineers, 1989, pp. 66-78.
cited by other.
|
Primary Examiner: Juska; Cheryl A.
Attorney, Agent or Firm: Frommer Lawrence & Haug LLP
Santucci; Ronald R.
Claims
What is claimed is:
1. A resin-impregnated endless belt for a long nip press or
calender, or for other papermaking and paper-processing
applications, said resin-impregnated endless belt comprising: a
base fabric, said base fabric being in the form of an endless loop
with an inner surface, an outer surface, a machine direction and a
cross-machine direction, said base fabric having machine-direction
(MD) structural elements and cross-machine-direction (CD)
structural elements wherein at least some of said MD structural
elements are spaced apart from one another by a distance in the
range from 0.0625 inch to 0.5 inch (0.16 cm to 1.27 cm), and
wherein at least some of said CD structural elements are spaced
apart from one another by a distance in the range from 0.0625 inch
to 0.5 inch (0.16 cm to 1.27 cm), said MD structural elements
crossing said CD structural elements at a plurality of crossing
points, said MD structural elements being joined to said CD
structural elements at said crossing points; and a coating of a
first polymeric resin on said inner surface of said base fabric,
said coating impregnating and rendering said base fabric
impermeable to liquids, and forming a layer on the inner surface
thereof, said coating being smooth and providing said belt with a
uniform thickness, wherein said base fabric is a woven structure,
said MD structural elements being MD yarns and said CD structural
elements being CD yarns, said MD yarns being woven with said CD
yarns to form said woven structure, wherein said MD yarns are woven
with said CD yarns in a plain weave, and wherein at least one of
said MD yarns and said CD yarns are coated with a thermoplastic
resin material, said thermoplastic resin material joining said MD
yarns to said CD yarns at said crossing points upon application of
a heat treatment on said base fabric after weaving.
2. A resin-impregnated endless belt for a long nip press or
calender, or for other papermaking and paper-processing
applications, said resin-impregnated endless belt comprising: a
base fabric, said base fabric being in the form of an endless loop
with an inner surface, an outer surface, a machine direction and a
cross-machine direction, said base fabric having machine-direction
(MD) structural elements and cross-machine-direction (CD)
structural elements wherein at least some of said MD structural
elements are spaced apart from one another by a distance in the
range from 0.0625 inch to 0.5 inch (0.16 cm to 1.27 cm), and
wherein at least some of said CD structural elements are spaced
apart from one another by a distance in the range from 0.0625 inch
to 0.5 inch (0.16 cm to 1.27 cm), said MD structural elements
crossing said CD structural elements at a plurality of crossing
points, said MD structural elements being joined to said CD
structural elements at said crossing points; and a coating of a
first polymeric resin on said inner surface of said base fabric,
said coating impregnating and rendering said base fabric
impermeable to liquids, and forming a layer on the inner surface
thereof, said coating being smooth and providing said belt with a
uniform thickness, wherein said base fabric is a woven structure,
said MD structural elements being MD yarns and said CD structural
elements being CD yarns, said MD yarns being woven with said CD
yarns to form said woven structure, wherein said MD yarns are woven
with said CD yarns in a plain weave, and wherein said MD yarns and
said CD yarns are joined to one another at said crossing points by
a chemical material applied to said base fabric after weaving.
3. A resin-impregnated endless belt for a long nip press or
calender, or for other papermaking and paper-processing
applications, said resin-impregnated endless belt comprising: a
base fabric, said base fabric being in the form of an endless loop
with an inner surface, an outer surface, a machine direction and a
cross-machine direction, said base fabric having machine-direction
(MD) structural elements and cross-machine-direction (CD)
structural elements wherein at least some of said MD structural
elements are spaced apart from one another by a distance in the
range from 0.0625 inch to 0.5 inch (0.16 cm to 1.27 cm), and
wherein at least some of said CD structural elements are spaced
apart from one another by a distance in the range from 0.0625 inch
to 0.5 inch (0.16 cm to 1.27 cm), said MD structural elements
crossing said CD structural elements at a plurality of crossing
points, said MD structural elements being joined to said CD
structural elements at said crossing points; and a coating of a
first polymeric resin on said inner surface of said base fabric,
said coating impregnating and rendering said base fabric
impermeable to liquids, and forming a layer on the inner surface
thereof, said coating being smooth and providing said belt with a
uniform thickness, wherein said base fabric is a woven structure,
said MD structural elements being MD yarns and said CD structural
elements being CD yarns, said MD yarns being woven with said CD
yarns to form said woven structure, wherein said MD yarns are woven
with said CD yarns in a plain weave, and wherein said MD yarns are
polyester multifilament yarns.
4. A resin-impregnated endless belt as claimed in claim 3 wherein
said polyester multifilament yarns have a denier of 3000.
5. A resin-impregnated endless belt for a long nip press or
calender, or for other papermaking and paper-processing
applications, said resin-impregnated endless belt comprising: a
base fabric, said base fabric being in the form of an endless loop
with an inner surface, an outer surface, a machine direction and a
cross-machine direction, said base fabric having machine-direction
(MD) structural elements and cross-machine-direction (CD)
structural elements wherein at least some of said MD structural
elements are spaced apart from one another by a distance in the
range from 0.0625 inch to 0.5 inch (0.16 cm to 1.27 cm), and
wherein at least some of said CD structural elements are spaced
apart from one another by a distance in the range from 0.0625 inch
to 0.5 inch (0.16 cm to 1.27 cm), said MD structural elements
crossing said CD structural elements at a plurality of crossing
points, said MD structural elements being joined to said CD
structural elements at said crossing points; and a coating of a
first polymeric resin on said inner surface of said base fabric,
said coating impregnating and rendering said base fabric
impermeable to liquids, and forming a layer on the inner surface
thereof, said coating being smooth and providing said belt with a
uniform thickness, wherein said base fabric is a woven structure,
said MD structural elements being MD yarns and said CD structural
elements being CD yarns, said MD yarns being woven with said CD
yarns to form said woven structure, wherein said MD yarns are woven
with said CD yarns in a plain weave, and wherein said CD yarns are
polyester multifilament yarns.
6. A resin-impregnated endless belt as claimed in claim 5 wherein
said polyester multifilament yarns have a denier of 3000.
7. A resin-impregnated endless belt for a long nip press or
calender, or for other papermaking and paper-processing
applications, said resin-impregnated endless belt comprising: a
base fabric, said base fabric being in the form of an endless loop
with an inner surface, an outer surface, a machine direction and a
cross-machine direction, said base fabric having machine-direction
(MD) structural elements and cross-machine-direction (CD)
structural elements wherein at least some of said MD structural
elements are spaced apart from one another by a distance in the
range from 0.0625 inch to 0.5 inch (0.16 cm to 1.27 cm), and
wherein at least some of said CD structural elements are spaced
apart from one another by a distance in the range from 0.0625 inch
to 0.5 inch (0.16 cm to 1.27 cm), said MD structural elements
crossing said CD structural elements at a plurality of crossing
points, said MD structural elements being joined to said CD
structural elements at said crossing points; and a coating of a
first polymeric resin on said inner surface of said base fabric,
said coating impregnating and rendering said base fabric
impermeable to liquids, and forming a layer on the inner surface
thereof, said coating being smooth and providing said belt with a
uniform thickness, wherein said base fabric is a woven structure,
said MD structural elements being MD yarns and said CD structural
elements being CD yarns, said MD yarns being woven with said CD
yarns to form said woven structure, wherein said MD yarns are woven
with said CD yarns in a single-layer weave wherein a plurality of
at least one of said MD yarns and said CD yarns weave side-by-side
one another, and wherein at least one of said MD yarns and said CD
yarns are coated with a thermoplastic resin material, said
thermoplastic resin material joining said MD yarns to said CD yarns
at said crossing points upon application of a heat treatment on
said base fabric after weaving.
8. A resin-impregnated endless belt for a long nip press or
calender, or for other papermaking and paper-processing
applications, said resin-impregnated endless belt comprising: a
base fabric, said base fabric being in the form of an endless loop
with an inner surface, an outer surface, a machine direction and a
cross-machine direction, said base fabric having machine-direction
(MD) structural elements and cross-machine-direction (CD)
structural elements wherein at least some of said MD structural
elements are spaced apart from one another by a distance in the
range from 0.0625 inch to 0.5 inch (0.16 cm to 1.27 cm), and
wherein at least some of said CD structural elements are spaced
apart from one another by a distance in the range from 0.0625 inch
to 0.5 inch (0.16 cm to 1.27 cm), said MD structural elements
crossing said CD structural elements at a plurality of crossing
points, said MD structural elements being joined to said CD
structural elements at said crossing points; and a coating of a
first polymeric resin on said inner surface of said base fabric,
said coating impregnating and rendering said base fabric
impermeable to liquids, and forming a layer on the inner surface
thereof, said coating being smooth and providing said belt with a
uniform thickness, wherein said base fabric is a woven structure,
said MD structural elements being MD yarns and said CD structural
elements being CD yarns, said MD yarns being woven with said CD
yarns to form said woven structure, wherein said MD yarns are woven
with said CD yarns in a single-layer weave wherein a plurality of
at least one of said MD yarns and said CD yarns weave side-by-side
one another, and wherein said MD yarns and said CD yarns are joined
to one another at said crossing points by a chemical material
applied to said base fabric after weaving.
9. A resin-impregnated endless belt for a long nip press or
calender, or for other papermaking and paper-processing
applications, said resin-impregnated endless belt comprising: a
base fabric, said base fabric being in the form of an endless loop
with an inner surface, an outer surface, a machine direction and a
cross-machine direction, said base fabric having machine-direction
(MD) structural elements and cross-machine-direction (CD)
structural elements wherein at least some of said MD structural
elements are spaced apart from one another by a distance in the
range from 0.0625 inch to 0.5 inch (0.16 cm to 1.27 cm), and
wherein at least some of said CD structural elements are spaced
apart from one another by a distance in the range from 0.0625 inch
to 0.5 inch (0.16 cm to 1.27 cm), said MD structural elements
crossing said CD structural elements at a plurality of crossing
points, said MD structural elements being joined to said CD
structural elements at said crossing points; and a coating of a
first polymeric resin on said inner surface of said base fabric,
said coating impregnating and rendering said base fabric
impermeable to liquids, and forming a layer on the inner surface
thereof, said coating being smooth and providing said belt with a
uniform thickness, wherein said base fabric is a woven structure,
said MD structural elements being MD yarns and said CD structural
elements being CD yarns, said MD yarns being woven with said CD
yarns to form said woven structure, wherein said MD yarns are woven
with said CD yarns in a single-layer weave wherein a plurality of
at least one of said MD yarns and said CD yarns weave side-by-side
one another, and wherein said MD yarns are polyester multifilament
yarns.
10. A resin-impregnated endless belt for a long nip press or
calender, or for other papermaking and paper-processing
applications, said resin-impregnated endless belt comprising: a
base fabric, said base fabric being in the form of an endless loop
with an inner surface, an outer surface, a machine direction and a
cross-machine direction, said base fabric having machine-direction
(MD) structural elements and cross-machine-direction (CD)
structural elements wherein at least some of said MD structural
elements are spaced apart from one another by a distance in the
range from 0.0625 inch to 0.5 inch (0.16 cm to 1.27 cm), and
wherein at least some of said CD structural elements are spaced
apart from one another by a distance in the range from 0.0625 inch
to 0.5 inch (0.16 cm to 1.27 cm), said MD structural elements
crossing said CD structural elements at a plurality of crossing
points, said MD structural elements being joined to said CD
structural elements at said crossing points; and a coating of a
first polymeric resin on said inner surface of said base fabric,
said coating impregnating and rendering said base fabric
impermeable to liquids, and forming a layer on the inner surface
thereof, said coating being smooth and providing said belt with a
uniform thickness, wherein said base fabric is a woven structure,
said MD structural elements being MD yarns and said CD structural
elements being CD yarns, said MD yarns being woven with said CD
yarns to form said woven structure, wherein said MD yarns are woven
with said CD yarns in a single-layer weave wherein a plurality of
at least one of said MD yarns and said CD yarns weave side-by-side
one another, and wherein said CD yarns are polyester multifilament
yarns.
11. A resin-impregnated endless belt for a long nip press or
calender, or for other papermaking and paper-processing
applications, said resin-impregnated endless belt comprising: a
base fabric, said base fabric being in the form of an endless loop
with an inner surface, an outer surface, a machine direction and a
cross-machine direction, said base fabric having machine-direction
(MD) structural elements and cross-machine-direction (CD)
structural elements wherein at least some of said MD structural
elements are spaced apart from one another by a distance in the
range from 0.0625 inch to 0.5 inch (0.16 cm to 1.27 cm), and
wherein at least some of said CD structural elements are spaced
apart from one another by a distance in the range from 0.0625 inch
to 0.5 inch (0.16 cm to 1.27 cm), said MD structural elements
crossing said CD structural elements at a plurality of crossing
points, said MD structural elements being joined to said CD
structural elements at said crossing points; and a coating of a
first polymeric resin on said inner surface of said base fabric,
said coating impregnating and rendering said base fabric
impermeable to liquids, and forming a layer on the inner surface
thereof, said coating being smooth and providing said belt with a
uniform thickness, wherein said base fabric is a woven structure,
said MD structural elements being MD yarns and said CD structural
elements being CD yarns, said MD yarns being woven with said CD
yarns to form said woven structure, wherein said CD yarns comprise
first and second paired CD yarns, said first and second paired CD
yarns being interwoven with said MD yarns in an endless leno weave,
said MD yarns and said CD yarns thereby being mechanically locked
to one another at said crossing points, and wherein at least one of
said MD yarns and said CD yarns are coated with a thermoplastic
resin material, said thermoplastic resin material joining said MD
yarns to said CD yarns at said crossing points upon application of
a heat treatment on said base fabric after weaving.
12. A resin-impregnated endless belt for a long nip press or
calender, or for other papermaking and paper-processing
applications, said resin-impregnated endless belt comprising: a
base fabric, said base fabric being in the form of an endless loop
with an inner surface, an outer surface, a machine direction and a
cross-machine direction, said base fabric having machine-direction
(MD) structural elements and cross-machine-direction (CD)
structural elements wherein at least some of said MD structural
elements are spaced apart from one another by a distance in the
range from 0.0625 inch to 0.5 inch (0.16 cm to 1.27 cm), and
wherein at least some of said CD structural elements are spaced
apart from one another by a distance in the range from 0.0625 inch
to 0.5 inch (0.16 cm to 1.27 cm), said MD structural elements
crossing said CD structural elements at a plurality of crossing
points, said MD structural elements being joined to said CD
structural elements at said crossing points; and a coating of a
first polymeric resin on said inner surface of said base fabric,
said coating impregnating and rendering said base fabric
impermeable to liquids, and forming a layer on the inner surface
thereof, said coating being smooth and providing said belt with a
uniform thickness, wherein said base fabric is a woven structure,
said MD structural elements being MD yarns and said CD structural
elements being CD yarns, said MD yarns being woven with said CD
yarns to form said woven structure, wherein said CD yarns comprise
first and second paired CD yarns, said first and second paired CD
yarns being interwoven with said MD yarns in an endless leno weave,
said MD yarns and said CD yarns thereby being mechanically locked
to one another at said crossing points, and wherein said MD yarns
and said CD yarns are joined to one another at said crossing points
by a chemical material applied to said base fabric after
weaving.
13. A resin-impregnated endless belt for a long nip press or
calender, or for other papermaking and paper-processing
applications, said resin-impregnated endless belt comprising: a
base fabric, said base fabric being in the form of an endless loop
with an inner surface, an outer surface, a machine direction and a
cross-machine direction, said base fabric having machine-direction
(MD) structural elements and cross-machine-direction (CD)
structural elements wherein at least some of said MD structural
elements are spaced apart from one another by a distance in the
range from 0.0625 inch to 0.5 inch (0.16 cm to 1.27 cm), and
wherein at least some of said CD structural elements are spaced
apart from one another by a distance in the range from 0.0625 inch
to 0.5 inch (0.16 cm to 1.27 cm), said MD structural elements
crossing said CD structural elements at a plurality of crossing
points, said MD structural elements being joined to said CD
structural elements at said crossing points; and a coating of a
first polymeric resin on said inner surface of said base fabric,
said coating impregnating and rendering said base fabric
impermeable to liquids, and forming a layer on the inner surface
thereof, said coating being smooth and providing said belt with a
uniform thickness, wherein said base fabric is a woven structure,
said MD structural elements being MD yarns and said CD structural
elements being CD yarns, said MD yarns being woven with said CD
yarns to form said woven structure, wherein said CD yarns comprise
first and second paired CD yarns, said first and second paired CD
yarns being interwoven with said MD yarns in an endless leno weave,
said MD yarns and said CD yarns thereby being mechanically locked
to one another at said crossing points, and wherein said MD yarns
are polyester multifilament yarns.
14. A resin-impregnated endless belt as claimed in claim 13 wherein
said polyester multifilament yarns have a denier of 3000.
15. A resin-impregnated endless belt for a long nip press or
calender, or for other papermaking and paper-processing
applications, said resin-impregnated endless belt comprising: a
base fabric, said base fabric being in the form of an endless loop
with an inner surface, an outer surface, a machine direction and a
cross-machine direction, said base fabric having machine-direction
(MD) structural elements and cross-machine-direction (CD)
structural elements wherein at least some of said MD structural
elements are spaced apart from one another by a distance in the
range from 0.0625 inch to 0.5 inch (0.16 cm to 1.27 cm), and
wherein at least some of said CD structural elements are spaced
apart from one another by a distance in the range from 0.0625 inch
to 0.5 inch (0.16 cm to 1.27 cm), said MD structural elements
crossing said CD structural elements at a plurality of crossing
points, said MD structural elements being joined to said CD
structural elements at said crossing points; and a coating of a
first polymeric resin on said inner surface of said base fabric,
said coating impregnating and rendering said base fabric
impermeable to liquids, and forming a layer on the inner surface
thereof, said coating being smooth and providing said belt with a
uniform thickness, wherein said base fabric is a woven structure,
said MD structural elements being MD yarns and said CD structural
elements being CD yarns, said MD yarns being woven with said CD
yarns to form said woven structure, wherein said CD yarns comprise
first and second paired CD yarns, said first and second paired CD
yarns being interwoven with said MD yarns in an endless leno weave,
said MD yarns and said CD yarns thereby being mechanically locked
to one another at said crossing points, and wherein said first and
second paired CD yarns are both polyester multifilament yarns.
16. A resin-impregnated endless belt as claimed in claim 15 wherein
said first and second paired CD yarns have a combined denier of
3000.
17. A resin-impregnated endless belt for a long nip press or
calender, or for other papermaking and paper-processing
applications, said resin-impregnated endless belt comprising: a
base fabric, said base fabric being in the form of an endless loop
with an inner surface, an outer surface, a machine direction and a
cross-machine direction, said base fabric having machine-direction
(MD) structural elements and cross-machine-direction (CD)
structural elements wherein at least some of said MD structural
elements are spaced apart from one another by a distance in the
range from 0.0625 inch to 0.5 inch (0.16 cm to 1.27 cm), and
wherein at least some of said CD structural elements are spaced
apart from one another by a distance in the range from 0.0625 inch
to 0.5 inch (0.16 cm to 1.27 cm), said MD structural elements
crossing said CD structural elements at a plurality of crossing
points, said MD structural elements being joined to said CD
structural elements at said crossing points; and a coating of a
first polymeric resin on said inner surface of said base fabric,
said coating impregnating and rendering said base fabric
impermeable to liquids, and forming a layer on the inner surface
thereof, said coating being smooth and providing said belt with a
uniform thickness, wherein said base fabric is a non-woven
structure, said MD structural elements being MD yarns and said CD
structural elements being CD yarns, said MD yarns being joined to
said CD yarns at said crossing points to form said non-woven
structure, wherein said MD yarns are bonded to said CD yarns at
said crossing points, and wherein at least one of said MD yarns and
said CD yarns are coated with a thermoplastic resin material, said
thermoplastic resin material joining said MD yarns to said CD yarns
at said crossing points upon application of a heat treatment.
18. A resin-impregnated endless belt for a long nip press or
calender, or for other papermaking and paper-processing
applications, said resin-impregnated endless belt comprising: a
base fabric, said base fabric being in the form of an endless loop
with an inner surface, an outer surface, a machine direction and a
cross-machine direction, said base fabric having machine-direction
(MD) structural elements and cross-machine-direction (CD)
structural elements wherein at least some of said MD structural
elements are spaced apart from one another by a distance in the
range from 0.0625 inch to 0.5 inch (0.16 cm to 1.27 cm), and
wherein at least some of said CD structural elements are spaced
apart from one another by a distance in the range from 0.0625 inch
to 0.5 inch (0.16 cm to 1.27 cm), said MD structural elements
crossing said CD structural elements at a plurality of crossing
points, said MD structural elements being joined to said CD
structural elements at said crossing points; and a coating of a
first polymeric resin on said inner surface of said base fabric,
said coating impregnating and rendering said base fabric
impermeable to liquids, and forming a layer on the inner surface
thereof, said coating being smooth and providing said belt with a
uniform thickness, wherein said base fabric is a non-woven
structure, said MD structural elements being MD yarns and said CD
structural elements being CD yarns, said MD yarns being joined to
said CD yarns at said crossing points to form said non-woven
structure, wherein said MD yarns are bonded to said CD yarns at
said crossing points, and wherein said MD yarns and said CD yarns
are joined to one another at said crossing points by a chemical
material.
19. A resin-impregnated endless belt for a long nip press or
calender, or for other papermaking and paper-processing
applications, said resin-impregnated endless belt comprising: a
base fabric, said base fabric being in the form of an endless loop
with an inner surface, an outer surface, a machine direction and a
cross-machine direction, said base fabric having machine-direction
(MD) structural elements and cross-machine-direction (CD)
structural elements wherein at least some of said MD structural
elements are spaced apart from one another by a distance in the
range from 0.0625 inch to 0.5 inch (0.16 cm to 1.27 cm), and
wherein at least some of said CD structural elements are spaced
apart from one another by a distance in the range from 0.0625 inch
to 0.5 inch (0.16 cm to 1.27 cm), said MD structural elements
crossing said CD structural elements at a plurality of crossing
points, said MD structural elements being joined to said CD
structural elements at said crossing points; and a coating of a
first polymeric resin on said inner surface of said base fabric,
said coating impregnating and rendering said base fabric
impermeable to liquids, and forming a layer on the inner surface
thereof, said coating being smooth and providing said belt with a
uniform thickness, wherein said base fabric is a non-woven
structure, said MD structural elements being MD yarns and said CD
structural elements being CD yarns, said MD yarns being joined to
said CD yarns at said crossing points to form said non-woven
structure, and wherein said MD yarns are polyester multifilament
yarns.
20. A resin-impregnated endless belt as claimed in claim 19 wherein
said polyester multifilament yarns have a denier of 3000.
21. A resin-impregnated endless belt for a long nip press or
calender, or for other papermaking and paper-processing
applications, said resin-impregnated endless belt comprising: a
base fabric, said base fabric being in the form of an endless loop
with an inner surface, an outer surface, a machine direction and a
cross-machine direction, said base fabric having machine-direction
(MD) structural elements and cross-machine-direction (CD)
structural elements wherein at least some of said MD structural
elements are spaced apart from one another by a distance in the
range from 0.0625 inch to 0.5 inch (0.16 cm to 1.27 cm), and
wherein at least some of said CD structural elements are spaced
apart from one another by a distance in the range from 0.0625 inch
to 0.5 inch (0.16 cm to 1.27 cm), said MD structural elements
crossing said CD structural elements at a plurality of crossing
points, said MD structural elements being joined to said CD
structural elements at said crossing points; and a coating of a
first polymeric resin on said inner surface of said base fabric,
said coating impregnating and rendering said base fabric
impermeable to liquids, and forming a layer on the inner surface
thereof, said coating being smooth and providing said belt with a
uniform thickness, wherein said base fabric is a non-woven
structure, said MD structural elements being MD yarns and said CD
structural elements being CD yarns, said MD yarns being joined to
said CD yarns at said crossing points to form said non-woven
structure, and wherein said CD yarns are polyester multifilament
yarns.
22. A resin-impregnated endless belt as claimed in claim 19 wherein
said polyester multifilament yarns have a denier of 3000.
23. A resin-impregnated endless belt for a long nip press or
calender, or for other papermaking and paper-processing
applications, said resin-impregnated endless belt comprising: a
base fabric, said base fabric being in the form of an endless loop
with an inner surface, an outer surface, a machine direction and a
cross-machine direction, said base fabric having machine-direction
(MD) structural elements and cross-machine-direction (CD)
structural elements wherein at least some of said MD structural
elements are spaced apart from one another by a distance in the
range from 0.0625 inch to 0.5 inch (0.16 cm to 1.27 cm), and
wherein at least some of said CD structural elements are spaced
apart from one another by a distance in the range from 0.0625 inch
to 0.5 inch (0.16 cm to 1.27 cm), said MD structural elements
crossing said CD structural elements at a plurality of crossing
points, said MD structural elements being joined to said CD
structural elements at said crossing points; and a coating of a
first polymeric resin on said inner surface of said base fabric,
said coating impregnating and rendering said base fabric
impermeable to liquids, and forming a layer on the inner surface
thereof, said coating being smooth and providing said belt with a
uniform thickness, wherein said base fabric is a non-woven
structure, said MD structural elements being MD yarns and said CD
structural elements being CD yarns, said MD yarns being joined to
said CD yarns at said crossing points to form said non-woven
structure, and wherein said base fabric further comprises a knitted
structure, said MD yarns and said CD yarns interweaving with said
knitted structure but not with each other, said knitted structure
thereby mechanically joining said MD yarns to said CD yarns at said
crossing points.
24. A resin-impregnated endless belt for a long nip press or
calender, or for other papermaking and paper-processing
applications, said resin-impregnated endless belt comprising: a
base fabric, said base fabric being in the form of an endless loop
with an inner surface, an outer surface, a machine direction and a
cross-machine direction, said base fabric having machine-direction
(MD) structural elements and cross-machine-direction (CD)
structural elements wherein at least some of said MD structural
elements are spaced apart from one another by a distance in the
range from 0.0625 inch to 0.5 inch (0.16 cm to 1.27 cm), and
wherein at least some of said CD structural elements are spaced
apart from one another by a distance in the range from 0.0625 inch
to 0.5 inch (0.16 cm to 1.27 cm), said MD structural elements
crossing said CD structural elements at a plurality of crossing
points, said MD structural elements being joined to said CD
structural elements at said crossing points; and a coating of a
first polymeric resin on said inner surface of said base fabric,
said coating impregnating and rendering said base fabric
impermeable to liquids, and forming a layer on the inner surface
thereof, said coating being smooth and providing said belt with a
uniform thickness, wherein said base fabric is an endless
Raschel-knitted structure, said MD structural elements being MD
yarns and said CD structural elements being Raschel-knitted CD
yarns, said MD yarns being laid into said Raschel-knitted CD yarns
during production of said endless Raschel-knitted structure, said
MD yarns thereby being mechanically interlocked with said
Raschel-knitted CD yarns.
25. A resin-impregnated endless belt as claimed in claim 24 wherein
at least one of said MD yarns and said CD yarns are coated with a
thermoplastic resin material, said thermoplastic resin material
further joining said MD yarns to said CD yarns at said crossing
points upon application of a heat treatment on said base fabric
after Raschel-knitting.
26. A resin-impregnated endless belt as claimed in claim 24 wherein
said MD yarns and said CD yarns are further joined to one another
at said crossing points by a chemical material applied to said base
fabric after Raschel knitting.
27. A resin-impregnated endless belt as claimed in claim 24 wherein
said MD yarns are polyester multifilament yarns.
28. A resin-impregnated endless belt as claimed in claim 27 wherein
said polyester multifilament yarns have a denier of 3000.
29. A resin-impregnated endless belt for a long nip press or
calender, or for other papermaking and paper-processing
applications, said resin-impregnated endless belt comprising: a
base fabric, said base fabric being in the form of an endless loop
with an inner surface, an outer surface, a machine direction and a
cross-machine direction, said base fabric having machine-direction
(MD) structural elements and cross-machine-direction (CD)
structural elements wherein at least some of said MD structural
elements are spaced apart from one another by a distance in the
range from 0.0625 inch to 0.5 inch (0.16 cm to 1.27 cm), and
wherein at least some of said CD structural elements are spaced
apart from one another by a distance in the range from 0.0625 inch
to 0.5 inch (0.16 cm to 1.27 cm), said MD structural elements
crossing said CD structural elements at a plurality of crossing
points, said MD structural elements being joined to said CD
structural elements at said crossing points; and a coating of a
first polymeric resin on said inner surface of said base fabric,
said coating impregnating and rendering said base fabric
impermeable to liquids, and forming a layer on the inner surface
thereof, said coating being smooth and providing said belt with a
uniform thickness, wherein said base fabric is an endless knitted
structure, said endless knitted structure, being knitted from a
yarn and stretched in both the machine and cross-machine directions
so that sections of said yarn align with said directions and become
said MD and CD structural elements, said endless knitted structure
being bonded in such a stretched condition to maintain the
alignment of said sections of said yarn in the machine and
cross-machine directions.
30. A resin-impregnated endless belt as claimed in claim 29 wherein
said yarn is coated with a thermoplastic resin material, said
thermoplastic resin material bonding said endless knitted structure
in said stretched condition upon application of a heat treatment on
said base fabric while so stretched.
31. A resin-impregnated endless belt as claimed in claim 29 wherein
said endless knitted structure is bonded in said stretched
condition by a chemical material applied thereto while so
stretched.
32. A resin-impregnated endless belt as claimed in claim 29 wherein
said yarn is a polyester multifilament yarn.
33. A resin-impregnated endless belt as claimed in claim 32 wherein
said polyester multifilament yarn has a denier of 3000.
.Iadd.34. A resin-impregnated endless belt for a long nip press or
calender, or for other papermaking and paper-processing
applications, said resin-impregnated endless belt comprising: a
base, said base being in the form of an endless loop with an inner
surface, an outer surface, a machine direction and a cross-machine
direction, said base having machine-direction (MD) structural
elements and cross-machine-direction (CD) structural elements, said
MD structural elements crossing said CD structural elements at a
plurality of crossing points, said MD structural elements being
joined to said CD structural elements at said crossing points; and
a coating of a first polymeric resin on said inner surface of said
base, said coating impregnating and rendering said base impermeable
to liquids, and forming a layer on the inner surface thereof, said
coating being smooth and providing said belt with a uniform
thickness, wherein said base is a non-woven structure, said MD
structural elements being MD yarns and said CD structural elements
being CD yarns, said MD yarns being joined to said CD yarns at said
crossing points to form said non-woven structure, wherein said MD
yarns are bonded to said CD yarns at said crossing points, and
wherein at least one of said MD yarns and said CD yarns are coated
with a thermoplastic resin material, said thermoplastic resin
material joining said MD yarns to said CD yarns at said crossing
points upon application of a heat treatment. .Iaddend.
.Iadd.35. A resin-impregnated endless belt for a long nip press or
calender, or for other papermaking and paper-processing
applications, said resin-impregnated endless belt comprising: a
base, said base being in the form of an endless loop with an inner
surface, an outer surface, a machine direction and a cross-machine
direction, said base having machine-direction (MD) structural
elements and cross-machine-direction (CD) structural elements, said
MD structural elements crossing said CD structural elements at a
plurality of crossing points, said MD structural elements being
joined to said CD structural elements at said crossing points; and
a coating of a first polymeric resin on said inner surface of said
base, said coating impregnating and rendering said base impermeable
to liquids, and forming a layer on the inner surface thereof, said
coating being smooth and providing said belt with a uniform
thickness, wherein said base is a non-woven structure, said MD
structural elements being MD yarns and said CD structural elements
being CD yarns, said MD yarns being joined to said CD yarns at said
crossing points to form said non-woven structure, wherein said MD
yarns are bonded to said CD yarns at said crossing points, and
wherein said MD yarns and said CD yarns are joined to one another
at said crossing points by a chemical material. .Iaddend.
.Iadd.36. A resin-impregnated endless belt for a long nip press or
calender, or for other papermaking and paper-processing
applications, said resin-impregnated endless belt comprising: a
base, said base being in the form of an endless loop with an inner
surface, an outer surface, a machine direction and a cross-machine
direction, said base having machine-direction (MD) structural
elements and cross-machine direction (CD) structural elements, said
MD structural elements crossing said CD structural elements at a
plurality of crossing points, said MD structural elements being
joined to said CD structural elements at said crossing points; and
a coating of a first polymeric resin on said inner surface of said
base, said coating impregnating and rendering said base impermeable
to liquids, and forming a layer on the inner surface thereof, said
coating being smooth and providing said belt with a uniform
thickness, wherein said base is a non-woven structure, said MD
structural elements being MD yarns and said CD structural elements
being CD yarns, said MD yarns being joined to said CD yarns at said
crossing points to form said non-woven structure, and wherein said
MD yarns are polyester multifilament yarns. .Iaddend.
.Iadd.37. A resin-impregnated endless belt as claimed in claim 36
wherein said polyester multifilament yarns have a denier of 3000.
.Iaddend.
.Iadd.38. A resin-impregnated endless belt for a long nip press or
calender, or for other papermaking and paper-processing
applications, said resin-impregnated endless belt comprising: a
base, said base being in the form of an endless loop with an inner
surface, an outer surface, a machine direction and a cross-machine
direction, said base having machine-direction (MD) structural
elements and cross-machine-direction (CD) structural elements, said
MD structural elements crossing said CD structural elements at a
plurality of crossing points, said MD structural elements being
joined to said CD structural elements at said crossing points; and
a coating of a first polymeric resin on said inner surface of said
base, said coating impregnating and rendering said base impermeable
to liquids, and forming a layer on the inner surface thereof, said
coating being smooth and providing said belt with a uniform
thickness, wherein said base is a non-woven structure, said MD
structural elements being MD yarns and said CD structural elements
being CD yarns, said MD yarns being joined to said CD yarns at said
crossing points to form said non-woven structure, and wherein said
CD yarns are polyester multifilament yarns. .Iaddend.
.Iadd.39. A resin-impregnated endless belt as claimed in claim 38
wherein said polyester multifilament yarns have a denier of 3000.
.Iaddend.
.Iadd.40. A resin-impregnated endless belt for a long nip press or
calender, or for other papermaking and paper-processing
applications, said resin-impregnated endless belt comprising: a
base, said base being in the form of an endless loop with an inner
surface, an outer surface, a machine direction and a cross-machine
direction, said base having machine-direction (MD) structural
elements and cross-machine-direction (CD) structural elements, said
MD structural elements crossing said CD structural elements at a
plurality of crossing points, said MD structural elements being
joined to said CD structural elements at said crossing points; and
a coating of a first polymeric resin on said inner surface of said
base, said coating impregnating and rendering said base impermeable
to liquids, and forming a layer on the inner surface thereof, said
coating being smooth and providing said belt with a uniform
thickness, wherein said base is a non-woven structure, said MD
structural elements being MD yarns and said CD structural elements
being CD yarns, said MD yarns being joined to said CD yarns at said
crossing points to form said non-woven structure, and wherein said
base further comprises a knitted structure, said MD yarns and said
CD yarns interweaving with said knitted structure but not with each
other, said knitted structure thereby mechanically joining said MD
yarns to said CD yarns at said crossing points. .Iaddend.
.Iadd.41. A resin-impregnated endless belt for a long nip press or
calender, or for other papermaking and paper-processing
applications, said resin-impregnated endless belt comprising: a
base, said base being in the form of an endless loop with an inner
surface, an outer surface, a machine direction and a cross-machine
direction, said base having machine-direction (MD) structural
elements and cross-machine-direction (CD) structural elements, said
MD structural elements crossing said CD structural elements at a
plurality of crossing points, said MD structural elements being
joined to said CD structural elements at said crossing points; and
a coating of a first polymeric resin on said inner surface of said
base, said coating impregnating and rendering said base impermeable
to liquids, and forming a layer on the inner surface thereof, said
coating being smooth and providing said belt with a uniform
thickness, wherein said base is an endless knitted structure, said
endless knitted structure, being knitted from a yarn and stretched
in both the machine and cross-machine directions so that sections
of said yarn align with said directions and become said MD and CD
structural elements, said endless knitted structure being bonded in
such a stretched condition to maintain the alignment of said
sections of said yarn in the machine and cross-machine directions.
.Iaddend.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to mechanisms for extracting water
from a web of material, and, more particularly, from a fibrous web
being processed into a paper product on a papermaking machine.
Specifically, the present invention is a method for manufacturing
resin-impregnated endless belt structures designed for use on a
long nip press of the shoe type on a papermaking machine, and for
other papermaking and paper-processing applications, and the belt
structures manufactured in accordance with the method.
2. Description of the Prior Art
During the papermaking process, a fibrous web of cellulosic fibers
is formed on a forming wire by depositing a fibrous slurry thereon
in the forming section of a papermachine. A large amount of water
is drained from the slurry in the forming section, after which the
newly formed web is conducted to a press section. The press section
includes a series of press nips, in which the fibrous web is
subjected to compressive forces applied to remove water therefrom.
The web finally is conducted to a drying section which includes
heated dryer drums around which the web is directed. The heated
dryer drums reduce the water content of the web to a desirable
level through evaporation to yield a paper product.
Rising energy costs have made it increasingly desirable to remove
as much water as possible from the web prior to its entering the
dryer section. As the dryer drums are often heated from within by
steam, costs associated with steam production can be substantial,
especially when a large amount of water needs to be removed from
the web.
Traditionally, press sections have included a series of nips formed
by pairs of adjacent cylindrical press rolls. In recent years, the
use of long press nips of the shoe type has been found to be more
advantageous than the use of nips formed by pairs of adjacent press
rolls. This is because the longer the time a web can be subjected
to pressure in the nip, the more water can be removed there, and,
consequently, the less water will remain behind in the web for
removal through evaporation in the dryer section.
The present invention relates to long nip presses of the shoe type.
In this variety of long nip press, the nip is formed between a
cylindrical press roll and an arcuate pressure shoe. The latter has
a cylindrically concave surface having a radius of curvature close
to that of the cylindrical press roll. When the roll and shoe are
brought into close physical proximity to one another, a nip which
can be five to ten times longer in the machine direction than one
formed between two press rolls is formed. Since the long nip is
five to ten times longer than that in a conventional two-roll
press, the so-called dwell time of the fibrous web in the long nip
is correspondingly longer under the same level of pressure per
square inch in pressing force used in a two-roll press. The result
of this new long nip technology has been a dramatic increase in
dewatering of the fibrous web in the long nip when compared to
conventional nips on paper machines.
A long nip press of the shoe type requires a special belt, such as
that shown in U.S. Pat. No. 5,238,537. This belt is designed to
protect the press fabric supporting, carrying and dewatering the
fibrous web from the accelerated wear that would result from
direct, sliding contact over the stationary pressure shoe. Such a
belt must be provided with a smooth, impervious surface that rides,
or slides, over the stationary shoe on a lubricating film of oil.
The belt moves through the nip at roughly the same speed as the
press fabric, thereby subjecting the press fabric to minimal
amounts of rubbing against the surface of the belt.
Belts of the variety shown in U.S. Pat. No. 5,238,537 are made by
impregnating a woven base fabric, which takes the form of an
endless loop, with a synthetic polymeric resin. Preferably, the
resin forms a coating of some predetermined thickness on at least
the inner surface of the belt, so that the yarns from which the
base fabric is woven may be protected from direct contact with the
arcuate pressure shoe component of the long nip press. It is
specifically this coating which must have a smooth, impervious
surface to slide readily over the lubricated shoe and to prevent
any of the lubricating oil from penetrating the structure of the
belt to contaminate the press fabric, or fabrics, and fibrous
web.
The base fabric of the belt shown in U.S. Pat. No. 5,238,537 may be
woven from monofilament yarns in a single- or multi-layer weave,
and is woven so as to be sufficiently open to allow the
impregnating material to totally impregnate the weave. This
eliminates the possibility of any voids forming in the final belt.
Such voids may allow the lubrication used between the belt and shoe
to pass through the belt and contaminate the press fabric or
fabrics and fibrous web. The base fabric may be flat-woven, and
subsequently seamed into endless form, or woven endless in tubular
form.
When the impregnating material is cured to a solid condition, it is
primarily bound to the base fabric by a mechanical interlock,
wherein the cured impregnating material surrounds the yarns of the
base fabric. In addition, there may be some chemical bonding or
adhesion between the cured impregnating material and the material
of the yarns of the base fabric.
Long nip press belts, such as that shown in U.S. Pat. No.
5,238,537, depending on the size requirements of the long nip
presses on which they are installed, have lengths from roughly 13
to 35 feet (approximately 4 to 11 meters), measured longitudinally
around their endless-loop forms, and widths from roughly 100 to 450
inches (approximately 250 to 1125 centimeters), measured
transversely across those forms.
It will be recognized that the length dimensions of the long nip
press belts given above include those for belts for both open- and
closed-loop presses. Long nip press belts for open-loop presses
generally have lengths in the range from 25 to 35 feet
(approximately 7.6 to 11 meters). The lengths (circumferences) of
long nip press belts for some of the current closed-loop presses
are set forth in the following table:
TABLE-US-00001 Belt Length Diameter (mm) Manufacturer Type (mm)
(Circumf.) Valmet Symbelt Press 1425 4477 Symbelt Press 1795 5639
Symbelt Press 1995 6268 Voith Flex-O-Nip 1270 3990 Flex-O-Nip 1500
4712 Nip-Co-Flex 1270 3990 Nip-Co-Flex 1500 4712 Intessa-S 1270
3990 Intessa-S 1550 4869 Beloit ENP-C 1511 4748 (59.5 inch) ENP-C
2032 6834 (80 inch)
It will be appreciated that the manufacture of such belts is
complicated by the requirement that the base fabric be endless
prior to its impregnation with a synthetic polymeric resin.
Nevertheless, belts of this variety have been successfully
manufactured for some years. However, two lingering problems remain
in the manufacturing process.
Firstly, it remains difficult to remove all of the air from the
base fabric during the impregnation and coating process. As implied
above, air remaining in the woven structure of the base fabric
manifests itself as voids in the final belt product. Such voids may
allow the lubrication used between the belt and the arcuate
pressure shoe to pass through the belt and contaminate the press
fabric or fabrics and fibrous web. As a consequence, it is
important to get all air out of the base fabric to achieve its
complete impregnation by the synthetic polymeric resin being
used.
Secondly, it remains difficult to provide the inner surface of the
belt with a layer of synthetic polymeric resin without inverting
the belt (turning it inside out) at some point during the
manufacturing process. It will be appreciated that belts of the
dimensions given above are not readily turned inside out, and that
the act of doing so places a great strain on the impregnating and
coating material, often leaving weak spots which may develop into
full-fledged holes through the belt. Accordingly, the widely used
technique of providing a layer of polymeric resin material on the
outside of the belt, and inverting of the belt to place the layer
on the inside, has not yielded consistently satisfactory
results.
The present invention provides a solution to these problems, which
characterize prior-art methods for manufacturing resin-impregnated
endless belt structures, by including the use of an endless base
fabric having a more open structure than those of the prior art to
decrease the likelihood that air will be trapped therewithin, and
by providing a layer of the polymeric resin material on the inner
surface of the belt without having to turn the belt inside out at
any time during the manufacturing process.
SUMMARY OF THE INVENTION
Accordingly, the object of the present invention is to provide a
method for manufacturing a resin-impregnated endless belt, and the
resulting belt product, for use in the papermaking process or in
other industrial applications where an endless belt, impermeable to
water, oil and other fluids, and having at least one smooth uniform
side, a uniform thickness, abrasion resistance and required
hardness characteristics, is desirable.
One such application is as a belt used on long nip presses of the
shoe type on paper machines. For this application, the belt needs
to be smooth and impervious to oil on the side that rides on the
lubricating oil film on the shoe, which forms one side of the nip.
The side away from the shoe can be smooth or can be provided with
void volume, in the form of grooves or blind-drilled holes, into
which water expressed from a paper web in the nip can pass.
A second such application is as a belt used for the calendering of
paper either in a roll nip or in a long shoe-type nip. Such a belt
is required to be smooth on both sides, impermeable to oil (when
used in a calender having a long shoe-type nip), of uniform
thickness, and having the hardnesses required for each side.
In its broadest form, the present resin-impregnated endless belt
comprises a base fabric in the form of an endless loop with an
inner surface, an outer surface, a machine direction and a
cross-machine direction. The base fabric has machine-direction (MD)
structural elements and cross-machine-direction (CD) structural
elements, wherein at least some of the MD structural elements are
spaced apart from one another by a distance in the range from
0.0625 inch to 0.5 inch (0.16 cm to 1.27 cm), and wherein at least
some of the CD structural elements are spaced apart from one
another by a distance in the range from 0.0625 inch to 0.5 inch
(0.16 cm to 1.27 cm). The MD structural elements cross or are
interwoven with the CD structural elements at a plurality of
crossing points, where the MD structural elements and the CD
structural elements are joined to one another. The joining may be
by mechanical, chemical or thermobonding means.
The belt further comprises a coating of a first polymeric resin on
the inner surface of the base fabric. The coating impregnates and
renders the base fabric impermeable to liquids, and forms a layer
on the inner surface thereof. The coating is smooth and provides
the belt with a uniform thickness. The resin impregnate fills the
space on the inside of the fabric, the voids in the fabric
structure, and provides a final layer of resin on the outside of
the fabric structure.
The method for manufacturing the present resin-impregnated endless
belt requires the use of a smooth, polished cylindrical mandrel,
which is rotatable about its longitudinal axis. The mandrel is
disposed so that its longitudinal axis is oriented in a horizontal
direction.
A spacer ring having an inside diameter equal to the diameter of
the cylindrical mandrel is disposed on and is slidable along the
cylindrical mandrel. The spacer ring has a thickness, measured
radially, equal to that desired for the layer of polymeric resin to
be formed on the inside surface of the base fabric.
The spacer ring, it follows, has an outside diameter equal to that
of the base fabric described above which is placed in sleeve-like
fashion over the mandrel and spacer ring. The base fabric is then
placed under tension in the longitudinal direction of the
cylindrical mandrel by suitable means.
The spacer ring is then moved to one end of the base fabric on the
cylindrical mandrel, and the mandrel is rotated about its
horizontally oriented longitudinal axis. Starting next to the
spacer ring, a first polymeric resin is dispensed onto and through
the base fabric in the form of a stream from a dispenser.
The spacer ring and dispenser are moved longitudinally along the
rotating cylindrical mandrel, the spacer ring moving ahead of the
dispenser, at a constant rate, so that the first polymeric resin
will be applied onto the base fabric in the form of a spiral of
preselected thickness. The spacer ring ensures that a layer of
desired thickness is provided on the inside surface of the base
fabric, while the base fabric is so impregnated.
The first polymeric resin cures by crosslinking as the coating
process proceeds across the base fabric. After completion of the
resin application, the outer surface of the belt may be finished to
a smooth surface or to a surface containing void volume.
The present method may be used to manufacture resin-impregnated
belt structures for use in all phases of the papermaking industry.
That is to say, that endless belt structures may be used as roll
covers, and calender belts, as well as on long nip presses of the
shoe type.
The several embodiments of the present invention will now be
described in more complete detail. In the description, frequent
reference will be made to the drawing figures identified
immediately below.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side cross-sectional view of a long nip press;
FIG. 2 is a perspective view of a belt made in accordance with the
method of the present invention;
FIG. 3 is a perspective view of an alternate embodiment of the
belt;
FIG. 4 is a perspective view of another embodiment of the belt;
FIG. 5 is a plan view of a base fabric, woven using the Leno
principle, for the belt of the present invention;
FIG. 6 is a cross-sectional view taken as indicated by line 6--6 in
FIG. 5;
FIG. 7 is a plan view of a knitted base fabric for the present
invention;
FIG. 8 is a plan view of another knitted base fabric for the
present invention;
FIG. 9 is a cross-sectional view of a base fabric, woven in a plain
weave, for the present invention;
FIG. 10 is a plan view of another woven base fabric for the present
invention;
FIG. 11 is a cross-sectional view of a non-woven base fabric for
the present invention;
FIG. 12 is a plan view of a knitted precursor for a base fabric for
the present invention;
FIG. 13 is a plan view of a stretched and bonded knitted base
fabric made from the precursor shown in FIG. 12;
FIG. 14 is a perspective view of the apparatus used to manufacture
the belts of the present invention;
FIG. 15 is a cross-sectional view of the belt embodiment shown in
FIG. 2, taken as indicated by line 15--15 in that figure;
FIG. 16 is a cross-sectional view, analogous to that given in FIG.
15, for a belt having a coating on both sides;
FIG. 17 is a cross-sectional view of the belt embodiment shown in
FIG. 3, taken as indicated by line 17--17 in that figure; and
FIG. 18 is a cross-sectional view of the belt embodiment shown in
FIG. 4, taken as indicated by line 18--18 in that figure.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A long nip press for dewatering a fibrous web being processed into
a paper product on a paper machine is shown in a side
cross-sectional view in FIG. 1. The press nip 10 is defined by a
smooth cylindrical press roll 12 and an arcuate pressure shoe 14.
The arcuate pressure shoe 14 has about the same radius of curvature
as the cylindrical press roll 12. The distance between the
cylindrical press roll 12 and the arcuate pressure shoe 14 may be
adjusted by hydraulic means operatively attached to arcuate
pressure shoe 14 to control the loading of the nip 10. Smooth
cylindrical press roll 12 may be a controlled crown roll matched to
the arcuate pressure shoe 14 to obtain a level cross-machine nip
profile.
Endless belt structure 16 extends in a closed loop through nip 10,
separating press roll 12 from arcuate pressure shoe 14. A wet press
fabric 18 and a fibrous web 20 being processed into a paper sheet
pass together through nip 10 as indicated by the arrows in FIG. 1.
Fibrous web 20 is supported by wet press fabric 18 and comes into
direct contact with smooth cylindrical press roll 12 in nip 10.
Fibrous web 20 and wet press fabric 18 proceed through the nip 10
as indicated by the arrows.
Alternatively, fibrous web 20 may proceed through the nip 10
between two wet press fabrics 18. In such a situation, the press
roll 12 may be either smooth or provided with void-volume means,
such as grooves or blind-drilled holes. Similarly, the side of
endless belt structure 16 facing the wet press fabrics 18 may also
be smooth or provided with void-volume means.
In any event, endless belt structure 16, also moving through press
nip 10 as indicated by the arrows, that is, counter-clockwise as
depicted in FIG. 1, protects wet press fabric 18 from direct
sliding contact against arcuate pressure shoe 14, and slides
thereover on a lubricating film of oil. Endless belt structure 16,
accordingly, must be impermeable to oil, so that wet press fabric
18 and fibrous web 20 will not be contaminated thereby.
A perspective view of belt 16 is provided in FIG. 2. The belt 16
has an inner surface 28 and an outer surface 30. The outer surface
30 is finished to a smooth surface.
FIG. 3 is a perspective view of an alternate embodiment of the belt
32. The belt 32 has an inner surface 34 and an outer surface 36.
The outer surface 36 is provided with a plurality of grooves 38,
for example, in the longitudinal direction around the belt 32 for
the temporary storage of water pressed from fibrous web 20 in press
nip 10.
Alternatively, the outer surface of the belt may be provided with a
plurality of blind-drilled holes arranged in some desired geometric
pattern for the temporary storage of water. FIG. 4 is a perspective
view of such an alternate embodiment of the belt 40. The belt 40
has an inner surface 42 and an outer surface 44. The outer surface
44 is provided with a plurality of blind-drilled holes 46, so
called because they do not extend completely through the belt 40.
Moreover, the blind-drilled holes 46 could also be connected to one
another by grooves.
The belt of the present invention includes a base fabric having
machine-direction (MD) and cross-machine-direction (CD) structural
elements and having a much higher open area than that
characterizing the base fabrics of the prior art. Because the base
fabric has such a high open area, it cannot be produced using
conventional techniques alone, which tend to leave a high-open-area
fabric sleazy, dimensionally unstable, and readily distorted. In
the present invention, the base fabric has an open structure in
which the MD and CD structural elements are joined to one another
at their crossing points by mechanical, chemical or thermal
means.
In one embodiment of the present invention, the base fabric is
woven in an endless leno weave. A plan view of such a base fabric
50 is shown in FIG. 5. Base fabric 50 is woven from warp yarns
52,54 and weft yarns 56. Warp yarns 52,54 twist one around the
other between picks of weft yarn 56. Warp yarns 52 remain on one
side of weft yarns 56, and are referred to as the ground threads.
Warp yarns 54 wrap over the other side of weft yarns 56 at each
crossing point 58, but wrap under warp yarns 52 between crossing
points 58 to mechanically lock the weft yarns 56 in position. Warp
yarns 54 are referred to as doup threads. This manner of weaving
gives firmness and strength to an open weave and prevents slipping
and displacement of the warp and weft yarns.
In an endless leno weave, warp yarns 52,54 are the CD yarns of the
endlessly woven base fabric 50, and the weft yarns 56 are the MD
yarns.
FIG. 6 is a cross-sectional view taken as indicated by line 6--6 in
FIG. 5 and illustrating how warp yarn 54 wraps under warp yarn 52
after each crossing point 58 to mechanically lock weft yarns 56 in
position.
Base fabric 50 may be woven from polyester multifilament yarns. In
such a case, each pair of warp yarns 52,54 may have a combined
denier of 3000, while the weft yarns 56 may themselves have a
denier of 3000. In general, the selection of the yarn denier is
dependent upon the final MD and CD strength required for the belt
to perform in the final application. The spacing between each pair
of warp yarns 52,54 may be in the range from 0.0625 inch to 0.5
inch (0.16 cm to 1.27 cm), and the spacing between each of the weft
yarns 56 may also be in the range from 0.0625 inch to 0.5 inch
(0.16 cm to 1.27 cm). As is well known to those of ordinary skill
in the art, base fabric 50 may be woven from other types of yarns,
such as monofilament and plied monofilament yarns, extruded from
other synthetic polymeric resins, such as polyamide resins.
In another embodiment of the present invention, the base fabric is
knitted by a circular or flat-bed knitting process in the form of
an endless loop. A plan view of such a base fabric 120 is shown in
FIG. 7. During the knitting process, MD yarns 122 and CD yarns 124
are laid into the knitted structure 126 formed by yarn 128, and
interweave with the loops formed by yarn 128, but not with each
other. The knitted structure 126 mechanically locks the MD yarns
122 and CD yarns 124 together.
Base fabric 120 may be produced from polyester multifilament yarns.
In such a case, MD yarns 122 and CD yarns 124 may each have a
denier of 3000, and yarns 128 forming knitted structure 126 may
also have a denier of 3000. The spacing between MD yarns 122 may be
in the range from 0.0625 inch to 0.5 inch (0.16 cm to 1.27 cm), and
the spacing between CD yarns 124 may also be in the range from
0.0625 inch to 0.5 inch (0.16 cm to 1.27 cm). As is well known to
those of ordinary skill in the art, base fabric 120 may be produced
from other types of yarns, such as monofilament and plied
monofilament yarns, extruded from other synthetic polymeric resins,
such as polyamide resins.
In still another embodiment of the present invention, the base
fabric is knitted by a Raschel knitting process in the form of an
endless loop. A plan view of such a base fabric 130 is shown in
FIG. 8. During the knitting process, MD yarns 132 are laid into the
Rachel-knitted CD yarns 134 formed by knitting strand 136. MD yarns
132 and CD yarns 134 are mechanically locked together by the
Raschel-knitted structure of CD yarns 134.
Base fabric 130 may be produced from polyester multifilament yarns.
In such a case, MD yarns 132 and strands 136 may each have a denier
of 3000. The spacing between MD yarns 132 may be in the range from
0.0625 inch to 0.5 inch (0.16 cm to 1.27 cm), and the spacing
between CD yarns 134 may also be in the range from 0.0625 inch to
0.5 inch (0.16 cm to 1.27 cm). As is well known to those of
ordinary skill in the art, base fabric 130 may be produced from
other types of yarns, such as monofilament and plied monofilament
yarns, extruded from other synthetic polymeric resins, such as
polyamide resins.
In an alternate embodiment of the present invention, the base
fabric is woven in a plain weave. FIG. 9 is a cross-sectional view
of such a base fabric 60, which may either be flat-woven, and
subsequently seamed into endless form, or woven endless. In the
former case, warp yarns 62 are in the machine direction of the base
fabric 60, and weft yarns 64 are in the cross-machine direction. In
the latter situation, warp yarns 62 are in the cross-machine
direction, and weft yarns 64 are in the machine direction.
Again, base fabric 60 may be woven from polyester multifilament
yarns. Warp yarns 62 and weft yarns 64 may each be polyester
multifilament yarns of about 3000 denier coated with a
thermoplastic resin material. The spacing between adjacent warp
threads 62 and between adjacent weft threads 64 may again be in the
range from 0.0625 inch to 0.5 inch (0.16 cm to 1.27 cm). Base
fabric 60 may also be woven from yarns of other varieties, such as
monofilament and plied monofilament yarns, extruded from other
synthetic polymeric resins, such as polyamide resins, as is
well-known to those of ordinary skill in the art. These other
varieties of yarns, too, may be coated with a thermoplastic resin
material.
After base fabric 60 is woven, it is exposed to a heat treatment
sufficient to soften the thermoplastic resin material coating the
warp yarns 62 and the weft yarns 64, so that they bond to one
another at the crossing points 66 to stabilize the weave structure.
Alternatively, instead of using yarns coated with a thermoplastic
resin material, the base fabric 60 may be woven from uncoated
polyester multifilament yarns of about 3000 denier, and, after
weaving, coated with a chemical material which bonds the warp yarns
62 to the weft yarns 64 at crossing points 66 to stabilize the
weave structure.
For example, base fabric 60 may be woven from warp yarns 62 and
weft yarns 64, which are both plied multifilament yarns comprising
bicomponent sheath/core filaments, wherein the sheath and core have
two different melting points. Yarns comprising filaments of this
type are available from Kanebo under the trademark BELL
COUPLE.RTM.. The filaments have a polyester core with a melting
point in a range from 100.degree. C. to 500.degree. C., and a
polyester copolymer sheath with a melting point in a range from
50.degree. C. to 450.degree. C. Filaments having denier in a range
from 0.5 to 40 are available. In practice, a 10- or 12-ply version
of a 250-denier multifilament yarn including 16 filaments twisted
together at a rate of 100 turns/meter (0.39 turns/inch) may be
used. The heat treatment would be carried out at a temperature
higher than the melting point of the sheath, but below the melting
point of the core to thermally bond the warp yarns 62 to the weft
yarns 64 at crossing points 66.
Warp yarns 62 and weft yarns 64 may alternatively be polyester
multifilament yarns having a thermoplastic polyurethane coating.
Yarns of this type are commonly used as tire cords, for which the
polyurethane acts as a tie coat to bond the yarn to the tire
material. The heat treatment would then be carried out at a
temperature between the melting points of the polyester and the
thermoplastic polyurethane, the latter, being the coating, having
the lower melting point.
Finally, as noted above, base fabric 60 may be woven from warp
yarns 62 and weft yarns 64 which are both uncoated polyester
multifilament yarns. After weaving, the base fabric 60 may then be
chemically treated with an acrylic, epoxy or other polymeric resin
coating material to chemically bond the warp yarns 62 to the weft
yarns 64 at crossing points 66.
In still another embodiment of the present invention, the base
fabric is woven in an open weave wherein three yarns weave
side-by-side in each direction of the fabric, each such triple
being separated from the next in each direction to provide the
fabric with a high open area. FIG. 10 is a plan view of such a base
fabric 140, which may either be flat-woven, and subsequently seamed
into endless form, or woven endless. In the former case, warp yarns
142 are in the machine direction of the base fabric 140, and weft
yarns 144 are in the cross-machine direction. In the latter
situation, warp yarns 142 are in the cross-machine direction, and
weft yarns 144 are in the machine direction. In either case, three
warp yarns 142 and three weft yarns 144 weave side-by-side one
another, and each said triple of yarns in each direction is
separated from the next to provide the fabric with a high open
area.
Base fabric 140 may be woven from polyester multifilament yarns.
Warp yarns 142 and weft yarns 144 may each be polyester
multifilament yarns of about 1000 denier coated with a
thermoplastic resin material. The spacing between each triple of
warp yarns 142 and weft yarns 144 may again be in the range from
0.0625 inch to 0.5 inch (0.16 cm to 1.27 cm). Base fabric 140 may
also be woven from yarns of other varieties, such as monofilament
and plied monofilament yarns, extruded from other synthetic
polymeric resins, such as polyamide resins, as is well-known to
those of ordinary skill in the art. These other varieties of yarns,
too, may be coated with a thermoplastic resin material.
After the base fabric 140 is woven, it is exposed to a heat
treatment sufficient to soften the thermoplastic resin material
coating the warp yarns 142 and the weft yarns 144, so that they
bond to one another at the crossing points 146 to stabilize the
weave structure. Alternatively, the other methods for stabilizing
the weave structure of base fabric 60, discussed above, may be
employed to stabilize base fabric 140.
In another embodiment of the present invention, the base fabric is
a non-woven fabric. FIG. 11 is a cross-sectional view of such a
base fabric 150, which includes MD yarns 152 and CD yarns 154,
which are bonded to one another at their crossing points 156. Base
fabric 150 is in endless-loop form. MD yarns 152 spiral around the
endless-loop form, which CD yarns 154 are disposed thereacross and
are bonded to MD yarns 152 at crossing points 156.
Base fabric 150 may be assembled from polyester multifilament
yarns. MD yarns 152 and CD yarns 154 may each be polyester
multifilament yarns of about 3000 denier coated with a
thermoplastic resin material. The spacing between MD yarns 152 and
between CD yarns 154 may again be in the range from 0.0625 inch to
0.5 inch (0.16 cm to 1.27 cm). Base fabric 150 may also be
assembled from yarns of other varieties, such as monofilament and
plied monofilament yarns, extruded from other synthetic polymeric
resins, such as polyamide resins, as is well-known to those of
ordinary skill in the art. These other varieties of yarns, too, may
be coated with a thermoplastic resin material.
As base fabric 150 is being assembled, it is exposed to a heat
treatment sufficient to soften the thermoplastic resin material
coating the MD yarns 152 and CD yarns 154 to bond them together at
their crossing points 156. Alternatively, the other methods for
stabilizing the weave structure of base fabric 60, discussed above,
may be employed to bond MD yarns 152 to CD yarns 154 at their
crossing points 156.
In yet another embodiment of the present invention, the base fabric
is a knitted fabric that is bonded after having been stretched as
far as possible in its machine and cross-machine directions. FIG.
12 is a plan view of a precursor 160 for a knitted base fabric
prior to being stretched and bonded.
Precursor 160 is knitted by a circular or flat-bed knitting process
in the form of an endless loop. The machine and cross-machine
directions, MD and CD, respectively, are as indicated in the
figure.
Precursor 160 may be knitted from a polyester multifilament yarn
162. The yarn 162 may have a denier of 3000 and a coating of a
thermoplastic resin material. As is well-known to those of ordinary
skill in the art, precursor 160 may be produced from other types of
yarns, such as monofilament and plied monofilament yarns, extruded
from other synthetic polymeric resins, such as polyamide resins.
These other varieties of yarns, too, may be coated with a
thermoplastic resin material.
Once the precursor 160 has been completely knitted, it is stretched
as far as possible in both the machine and cross-machine
directions. When this is done, loops 164 completely close, and the
precursor 160 takes the form of base fabric 170, shown in plan view
in FIG. 13. While held in such a configuration, base fabric 170 is
exposed to a heat treatment sufficient to soften the thermoplastic
resin material coating the yarn 162, so that the sections 172
oriented in the cross-machine direction bond to one another, and
the sections 174 oriented in the machine direction bond to the
sections 172 oriented in the cross-machine direction at crossing
points 176, thereby stabilizing the structure of base fabric 170.
Alternatively, the other methods for stabilizing the weave
structure of base fabric 60, discussed above, may be employed to
stabilize base fabric 170.
Sections 172, oriented in the cross-machine direction, and sections
174, oriented in the machine direction, are separated from one
another by amounts in the range from 0.0625 inch to 0.5 inch (0.16
cm to 1.27 cm).
In any event, the exact materials and sizes of the yarns in the
structure of any of the base fabrics described above may be varied
to meet the mechanical requirements of the application for which
the belt of the invention is intended. In addition, the yarns of
the base fabrics may be coated with a polymeric resin having a
chemical affinity for that to be used to impregnate the base
fabrics to act as a tie coat between the impregnating resin and the
base fabrics and to which the impregnating resin will chemically
bond.
FIG. 14 is a perspective view of the apparatus used to manufacture
the belts of the present invention. The apparatus 70 comprises a
cylindrical process roll or mandrel 72 having a smooth and polished
surface. Preferably, the surface of mandrel 72 is coated with a
material, such as polyethylene, polytetrafiuoroethylene (PTFE) or
silicone, which will readily release a polymeric resin material
cured thereon.
A base fabric 74, of one of the constructions set forth above, is
disposed in sleeve-like fashion upon the mandrel 72. The diameter
of the endless loop formed by the base fabric 74 is equal to the
diameter of the cylindrical mandrel 72 plus twice the thickness of
the layer of polymeric resin required on the inside of the belt
being produced, that thickness being measured between the base
fabric 74 and the inside surface of the belt being
manufactured.
A fixed clamping ring 76 fixes the base fabric 74 at one end of the
mandrel 72. A movable clamping tension ring 78 is disposed at the
other end of the mandrel 72, and places the base fabric 74 under
tension longitudinally with respect to the mandrel 72, that is, in
the cross-machine-direction of the base fabric 74. Both the fixed
clamping ring 76 and the movable clamping tension ring 78 have
clamping surfaces of a diameter equal to that of the base fabric
74.
A spacer ring 80, having a thickness equal to that desired for the
layer of polymeric resin on the inside of the belt being
manufactured, is disposed about the mandrel 72 beneath the base
fabric 74. The spacer ring 80 is axially translated along the
mandrel 72 by cables 82, which are wound onto take-up drum 84 by
motor 86.
During the coating of the base fabric 74, the mandrel 72 is
disposed so that its axis is oriented in a horizontal direction,
and is rotated about that axis by another motor or device not shown
in FIG. 14. A dispenser 88 of polymeric resin is disposed about the
horizontally oriented mandrel 72, and applies polymeric resin onto
the base fabric 74 substantially at the topmost point of the
rotating mandrel 72. The base fabric 74, as described above, has a
sufficiently high open area to allow the polymeric resin to flow
unimpeded therethrough filling the space between the base weave and
the mandrel.
The polymeric resin impregnates the base fabric 74, and renders the
belt being manufactured impervious to oil and water. The polymeric
resin may be polyurethane, and preferably is a 100% solids
composition thereof. The use of a 100% solids resin system, which
by definition lacks a solvent material, enables one to avoid the
formation of bubbles in the polymeric resin during the curing
process through which it proceeds following its application onto
the base fabric 74.
The mandrel 72 is disposed with its longitudinal axis oriented in a
horizontal direction, and rotated thereabout. A stream 90 of
polymeric resin is applied to the outside of the base fabric 74 by
starting at one end of the mandrel 72, for example, at movable
clamping tension ring 78, and by proceeding longitudinally along
the mandrel 72 as it rotates. The dispenser 88 is translated
longitudinally above the mandrel 72 at a preselected rate to apply
the polymeric resin to the base fabric 74 in the form of a spiral
stream. To support the base fabric 74, the spacer ring 80 also
proceeds longitudinally along the mandrel 72 just ahead of the
application edge of the resin stream 90.
In order for the polymeric resin to penetrate the base fabric 74 to
form a resin layer on the inside of the base fabric 74 without
entrapping air bubbles therewithin, the openness of the base fabric
74 and the viscosity of the polymeric resin at the point of
application are important factors. That is to say, the openness of
the base fabric 74 must be sufficiently high, and the viscosity of
the resin sufficiently low, to enable the polymeric resin to
penetrate readily through the base fabric 74 without entrapping air
bubbles. Further, the polymeric resin must be able to cross-link to
the "green state", where it has cured to a point where it will no
longer flow as a liquid, in a time less than that needed for the
mandrel 72 to make approximately one third of a revolution. In this
way, the polymeric resin will cross-link to the "green state"
before the rotation of the mandrel 72 brings it to a point where it
would otherwise be able to flow or drip from the mandrel 72.
The flow rate of the stream 90 of polymeric resin can be controlled
merely to penetrate the base fabric 74 and to provide a layer on
the inside thereof, or to provide a layer on the inside of the base
fabric 74, to fill the voids in the base fabric 74, and, possibly,
to provide a layer of polymeric resin on the outside of the base
fabric 74.
Further, in an alternate embodiment of the present invention, two
streams of polymeric resin can be applied onto the base fabric 74
from two dispensers 88, one stream being applied over the other. In
this situation, the first stream of polymeric resin may provide
sufficient resin to penetrate the base fabric 74 and to form a
layer on the inside thereof down to the surface of the mandrel 72.
The first stream may also fill the base fabric 74, and form a thin
layer on the outside thereof. The second stream of polymeric resin
may then provide a layer on the outside of the base fabric 74 and
coating formed by the first steam of polymeric resin. Using this
approach, the first stream can be of one polymeric resin and the
second stream can be of another polymeric resin. This is desirable
where the coatings on each side of the belts being manufactured are
required to have different hardnesses, such as, for example, is the
case with an LNP belt having grooves or holes on its outer surface
or with a calender belt.
FIG. 15 is a cross-sectional view of belt 16 taken as indicated by
line 15--15 in FIG. 2. The cross section is taken in the
transverse, or cross-machine, direction of belt 16, and shows that
belt 16 includes a base fabric 92 of the variety shown in FIGS. 5
and 6. That is, base fabric 92 is woven in an endless leno weave
from warp yarns 94,96 and weft yarns 98. Warp yarns 94,96, viewed
from the side in FIG. 15, are in the cross-machine direction of the
belt 16; weft yarns 98, seen in cross section, are in the machine
direction of the belt 16. Crossing points 100, where warp yarns 96
weave over weft yarns 98, may be visible on the outer surface 30 of
belt 16, also known as the felt side of belt 16.
The inner surface 28 of belt 16, also known as the shoe side of
belt 16, is formed by a polymeric resin coating 102. The polymeric
resin 102 impregnates the base fabric 92, and renders the belt 16
impervious to oil and water. Belt 16 is produced using apparatus 70
shown in FIG. 14, wherein stream 90 is controlled to provide a
layer of polymeric resin 102 on the inside of the base fabric 92,
to fill the voids in the base fabric 92, and to provide a layer of
polymeric resin 102 covering crossing points 100 on the outside of
base fabric 92. After polymeric resin 102 is cured, it may be
ground and polished to provide it with a smooth surface and the
belt 16 with a uniform thickness.
It may often be desirable to have a polymeric resin coating on both
sides of the base fabric of a belt of this kind to ensure that the
neutral axis of bending of the belt coincides with the base fabric.
Where this is the case, the repeated flexing of the belt as it
passes over the arcuate pressure shoe is less likely to cause the
polymeric resin coating to break away and delaminate from the base
fabric. Further, any polymeric resin coating on the outside of the
belt (that is, the felt side) may be provided with grooves,
blind-drilled holes, indentations or the like in some geometric
pattern to provide a sink for the temporary storage of water
pressed from fibrous web 20 in the press nip 10. Using apparatus
70, the polymeric resin coating on the outside of the belt may be
the same or different from that on the inside of the belt, as
discussed above.
In this regard, FIG. 16 is a cross-sectional view, analogous to
that given in FIG. 15, for a belt 110 having a coating of a first
polymeric resin 112 on the inside of base fabric 92, and a coating
of a second polymeric resin 114 on the outside of base fabric 92.
Apparatus 70 is used to manufacture belt 110. A first dispenser 88
applies first polymeric resin 112 onto base fabric 92 in an amount
sufficient to penetrate base fabric 92 and to form a layer on the
inside thereof down to the surface of the mandrel 72 and to fill
the base fabric 92. A second dispenser 88 applies second polymeric
resin 114 in an amount sufficient to cover the first polymeric
resin 112 and base fabric 92 and to form a layer of second
polymeric resin 114 thereover. First and second polymeric resins
112, 114 both render the belt 110 impervious to oil and water.
After first and second polymeric resins 112,114 have been cured,
second polymeric resin 114 may be ground and polished to provide it
with a smooth surface and the belt 110 with a uniform
thickness.
In addition, following the grinding and polishing of second
polymeric resin 114, it may be provided with grooves, blind-drilled
holes, or other indentations for the temporary storage of water
pressed from a paper web. For example, FIG. 17 is a cross-sectional
view of belt 32 taken as indicated by line 17--17 in FIG. 3. Belt
32 is constructed in the same manner as belt 110 of FIG. 16. After
first and second polymeric resins 112,114 have been cured, and
second polymeric resin 114 ground and polished to provide it with a
smooth surface and belt 32 with a uniform thickness, grooves 38 may
be cut into the outer surface 36 of belt 32. It will be clear to
those of ordinary skill in the art that the layer of second
polymeric resin 114 should be of a thickness sufficient to enable
grooves 38 to be cut without reaching base fabric 92.
Similarly, FIG. 18 is a cross-sectional view of belt 40 taken as
indicated by line 18--18 in FIG. 4. Belt 40 is also constructed in
the same manner as belt 110 of FIG. 16. After first and second
polymeric resins 112,114 have been cured, and second polymeric
resin 114 ground and polished to provide it with a smooth surface
and belt 40 with a uniform thickness, blind-drilled holes 46 may be
drilled into the outer surface 44 of belt 40. It will again be
clear to those of ordinary skill in the art that the layer of
second polymeric resin 112 should be of a thickness sufficient to
enable blind-drilled holes 46 to be drilled without reaching base
fabric 92.
It should be understood, as implied above, that belts 110,32,40,
shown in cross section in FIGS. 16, 17 and 18, respectively, may be
manufactured using only one polymeric resin, rather than two, that
is, rather than a first and second polymeric resin 112,114. In
those cases, the polymeric resin penetrates the base fabric 92 to
provide a layer on the inside thereof, to fill the voids therein,
and to provide a layer on the outside thereof of sufficient
thickness to enable grooves 38 to be cut or blind-drilled holes 46
to be drilled without reaching base fabric 92.
The polymeric resins used in the practice of the present invention
are preferably of the reactive type, either chemically cross-linked
with a catalyst or cross-linked with the application of heat.
Resins having a 100% solids composition, that is, lacking a
solvent, are preferred, as solvents tend to generate bubbles during
the curing process. Polyurethane resins having 100% solids
compositions are preferred.
The apparatus 70 used in the practice of the present invention
enables a smooth layer of polymeric resin to be disposed on the
inside of a paper processing belt without the necessity of
inverting (turning inside out) the belt at any time during the
manufacturing process. However, because the polymeric resin will
tend to stick to the smooth, polished cylindrical mandrel 72, it
may be desirable to provide the mandrel 72 with a sleeve or coating
to facilitate the removal of the belt therefrom when the polymeric
resin has been cured. Polyethylene, polytetrafluoroethylene (PTFE)
or silicone may be used for this purpose.
Modifications to the above would be obvious to those of ordinary
skill in the art, but would not bring the invention so modified
beyond the scope of the appended claims.
* * * * *