US20070044931A1

US20070044931A1 - Process belt with improved on-machine seam

Info

Publication number: US20070044931A1
Application number: US11/509,197
Authority: US
Inventors: Robert Crook; William Aldrich
Original assignee: Voith Patent GmbH
Current assignee: Voith Patent GmbH
Priority date: 2005-08-26
Filing date: 2006-08-23
Publication date: 2007-03-01

Abstract

A process belt having a woven base fabric, a barrier on an upper surface of the base fabric, a fibrous batt layer on the barrier and needled through the barrier and into the base fabric forms a composite structure. When an additional material is applied, the barrier protects a predetermined seam loop area from significant contamination by the additional material, resulting in a seam loop area that is substantially clear of obstruction so that a pintle can be installed faster and easier with less damage to the loop yams.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §121 of U.S. Patent Application No. 60/711,588 filed 26 Aug. 2005, the disclosure of which is expressly incorporated by reference herein in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A COMPACT DISK APPENDIX

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The invention relates to a fabric used in papermaking. More specifically, the present invention relates to a process belt having an improved seam and method for seaming preparation and sealing on a papermachine.
2. Description of Background
EP1127976 A2 and U.S. Pat. No. 6,712,940, are incorporated herein by reference. These patents disclose a papermachine belt having a thermoplastic composite surface, the belt is on-machine seamed, and the belt is seam sealed using thermoplastic means and materials.
Various methods are known for seaming paper machine fabrics along with the use of resin materials. For example, in U.S. Pat. No. 2,151,329, a process belt has a resin coated surface. The belt is cut over the seam, and a mixture of resin and blowing agent is applied to the cut after the belt is pinned on the paper machine. Heat is then applied to activate the blowing agent to foam and fill the voids and cure the resin.
In U.S. Pat. No. 5,601,877, the belt is processed similarly to U.S. Pat. No. 2,151,329 discussed above, except the seam is impregnated with the viscous paste.
In U.S. Pat. No. 4,948,646 for a seam felt, the surface of the seam flap is provided with a resilient support material to impart a compression recovered thickness equal to or greater than the rest of the felt. This is then held in place utilizing a low melt adhesive.
In U.S. Pat. No. 5,789,052 for a processing belt, the coating that is used is of a polymeric resin material. The seam is covered on the uncoated side of the belt with an encapsulating material. The encapsulating material is a paste of resin and foaming agent.
It is also known to add silicone “silastic” to the roll side of seam felts after pinning on the paper machine.
It is also known to add a polyamide resin to the seam from the sheetside after pinning on the paper machine.
There is, however, an inherent problem when the coating materials flow or otherwise migrate into the seaming areas in that it becomes difficult to impossible to get a pintel through the holes in the seam area.
In older methods, no flap is formed, rather a gap is created that must be filled with resin, foaming agent, etc. on the paper machine. It is well known that this method in practice leads to sheet marking from the seam, from, for example, uneven application of the resin paste, uneven high temperature curing on the paper machine, and/or the resin paste losing adhesion in use, and/or wearing off to create a nonuniform gap. Furthermore, the cured resin paste will not have the same smoothness and surface properties compared to the rest of the felt, both when the felt is new and when it wears, which also leads to sheet marking and sheet transfer difficulties.
Accordingly, there is a need for a method of applying coating materials to a fabric such that the coating materials do not interfere with the seaming process and for a fabric having a coating material that is not interfering with pintel insertion during the seaming process.

BRIEF SUMMARY OF THE INVENTION

Accordingly, the present invention is for an on-machine belt used in papermaking, and more particularly, to a process belt having an additional material and a method of applying the additional material at a seam area. In the preferred embodiment, the belt has a barrier in the batt structure that prevents the additional material from flowing or migrating into seam loops, resulting in substantially clear seam loops within which pintles can pass through. The additional material can be, for example, a coating, the deposition of solid particles that can be later melted, and others.
Additionally, the present invention is for a method of applying a barrier in the batt structure to prevent the additional material from getting into the seam loop region.
The preferred embodiment of the present invention is for a process belt with an additional material. For example, for a transfer belt, it is preferable that the additional material be a coating that is impermeable. The problem to be solved is that if the additional material gets into the seam, and more specifically the seam loops, it becomes difficult, if not impossible, to pass the pintel through the seam. Accordingly, a barrier is placed in the batt structure above the seam region to prevent the additional material (e.g. resin) from getting into the seam loops, thereby keeping the seam loops “clean” so a pintel can pass through. The barrier, for example a strip, is placed over at least one side of the seam area, preferably on the side from which the additional material was added. The barrier is placed in the batt structure to allow continuity of the additional material throughout the length of the fabric.
The barrier, or strip, also called a flow control material, and the material make-up of the barrier or strip depends on the additional material that is used.
If the additional material is a thermoplastic resin, the barrier can be a spunbond or carded nonwoven with a hydrophobic treatment. The hydrophobic treatment can be, for example, a TEFLON material or silicone material.
The barrier is preferably a solid film, for example, polyester, having a thickness of approximately 2-4 mils. The barrier can also be a tape such as kapton tape, plastic film, and others, and may have inherent hydrophobic properties. Still further, the barrier layer may also be relatively thick sheet side batt, that is, batt material that has a greater thickness or density than the surrounding batt material such that this batt material acts as a relative barrier compared to the surrounding batt material.
With respect to permeability of the barrier, in the preferred embodiment it should be denser than the surrounding batt structure, and capable of being needle punched.
Starting with a process belt as disclosed in U.S. Pat. No. 6,712,940, incorporated herein by reference, for example, the preferred embodiment of the present invention includes the addition of a layer of nonwoven fiber or other barrier layer or strip positioned between the seam loop yams and the surface composite layer. The purpose and advantage of this non-woven layer is to prevent penetration of the surface resinous material into the seam loop yam area and/or pintle, thereby making the seam opening relatively clean and relatively clear of obstruction. The result is that subsequent installation of the pintle is faster and easier, with a less damage done to the critical loop yarns.
When in position over the seam loop area, the barrier layer allows surface resin to extend directly and continuously over the seam loop area while not penetrating the loops that are to receive the pintle. Methods with no barrier must avoid application over the seam area entirely, creating a wide gap over the seam that must be completely filled in on the paper machine.
The preferred embodiment of the present invention also allows for the belt seam to be prepared similarly to a press felt seam, whereby the pintle is removed, and the nonwoven barrier layer and the surface layer are cut by a razor or similar instrument in a fine, thin line, preferably at a diagonal to the running the direction of the belt, to create a “flap” over the entire seam, preventing marking of the sheet from the seam.
Use of a belt flap results in good sheet physical/pressure mark resistance and continuity of smoothness, however water flowing through the belt can cause a disruption of the sheet to surface furnish/fillers and appear as a mark. This invention solves this problem by applying an adhesive to both sides of the cut flap during pinning on the paper machine, and the two sides are “closed”, essentially making this interface impermeable to water, thereby preventing a water mark. The adhesive used on the flap can be, for example, a silicone or polyurea. No heating or high temperature curing is required on the paper machine, simplifying the process. This also reduces down time for the customer, and eliminates critical variables that could cause inconsistent results as in the prior art.
Another advantage of this is that the adhesive is not exposed directly to surface wear and abrasion. Additionally, all the work can be done from the sheet side during pinning, resulting in a very practical advantage for speed and safety on wide paper machines.
This combination of belt seam cut flap, which is a result of the nonwoven barrier layer preventing resin penetration into the loops, and application of simple chemical adhesive applied to the seam of flap side during pinning, provides a consistent, cost-effective, less sheet market prone, and functional improvement for seam process paper machine belts.
In another embodiment, when the surface resin material is a thermoplastic material, heat can be applied to the closed flap edges after pinning, in order to thermally fuse the two sides to each other, effectively blocking water flow.
It should be noted that the invention does not require a thermoplastic composite surface, therefore resinous coatings could also be effectively used.
These and other features and advantages of this invention are described in or are apparent from the following detailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The preferred embodiments of the present inventions is further described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of exemplary embodiments of the present invention, in which like reference numerals represent similar parts throughout the several views of the drawings, and wherein:
FIG. 1 is a cross-section of a prior art paper machine belt;
FIG. 2 is cross sectional perspective view of a fabric of the present invention; and
FIG. 3 is a cross-sectional view of a fabric of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show structural details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the present invention may be embodied in practice.
FIG. 1 shows a cross section of a papermachine belt 10 known in the art. A woven base fabric 12, with minimal batt needled to it, provides a support structure. A nonwoven material 14, made of a thermoplastic material, is laid on to the upper surface of the base fabric 12. A fibrous batt layer 16 is placed over the membrane 14, and the batt 16 is then needled through the membrane 14 and into the base fabric 12, forming a composite structure 18.
After needling, this composite structure 18 is subjected to heat and pressure, for example, by tensioning of this endless composite structure 18 around a heated roll. This heat and pressure fuses the nonwoven material 14 and causes the fused nonwoven material 14 to flow through the fibrous batt 16. This produces a resinous surface with embedded fibers.
The preferred embodiment of the present invention is shown in FIGS. 2 and 3 for a process belt 100 with an additional material 102. The problem to be solved is that if the additional material gets into the seam area 104, or more specifically the seam loops 106, it becomes difficult, if not impossible, to pass the pintel 108 through the seam. Accordingly, a barrier 110 is placed in the batt structure 112 above the seam region 104 to prevent the additional material 102, for example resin, from getting into the seam loops 106, thereby keeping the seam loops “clean” so a pintel 108 can pass through.
The barrier 110 can be a strip that is placed over at least one side of the seam area, preferably on the side of the fabric 100 from which the additional material is introduced. The barrier 110 is placed in the batt structure 112 to allow continuity of the additional material throughout the length of the fabric.
The barrier or strip 110, can also be called a flow control material, and the material make-up of the barrier or strip depends on the coating that is used.
If the additional material 102 is a thermoplastic resin, the barrier 110 can be a spunbond or carded nonwoven with a hydrophobic treatment. The hydrophobic treatment can be, for example, a TEFLON material or silicone material.
The barrier 110 is preferably a solid film, for example, polyester, having a thickness of approximately 1-5 mils, preferably 2-4 mils. The barrier can also be kapton tape, plastic film, and others, and may have inherent hydrophobic properties. Still further, the barrier 110 may also be relatively thick sheet side batt, that is, batt material that has a greater thickness or density than the surrounding batt material such that this batt material acts as a relative barrier compared to the surrounding batt material. The batt material, or other material used for the barrier 110, may be so fine as it forms a physical barrier to the penetration of the additional material such as resin.
With respect to permeability of the barrier 110, in the preferred embodiment the barrier permeability should be denser than the surrounding batt structure 112, and capable of being needle punched.
For example, starting with a process belt 10 as disclosed in U.S. Pat. No. 6,712,940 and depicted in FIG. 1, the preferred embodiment of the present invention includes the addition of a layer of nonwoven fiber or other barrier layer or strip 110 positioned between the seam loop yams 114 and the surface composite layer 116. The purpose and advantage of this non-woven layer 110 is to prevent penetration of the surface resinous material 102 into the seam loop yam area 104 and/or pintle 108, thereby making the seam opening relatively clean and relatively clear of obstruction. The result is that subsequent installation of the pintle 108 is faster and easier, with a less damage done to the critical loop yams 114.
When in position over the seam loop area 104, the barrier layer 110 allows surface resin 102 to extend directly and continuously over the seam loop 104 area while not penetrating the loops that are to receive the pintle 108.
The preferred embodiment of the present invention also allows for the belt seam to be prepared similarly to a press felt seam, whereby the pintle 108 is removed, and the nonwoven barrier layer 110 and the surface layer 116 are cut by a razor or similar instrument in a fine, thin line, preferably at a diagonal to the running the direction of the belt 100. This creates a “flap” over the entire seam, preventing marking of the sheet from the seam.
Use of a belt flap results in good sheet physical/pressure mark resistance and continuity of smoothness, however water flowing through the belt can cause a disruption of the sheet to surface furnish/fillers and appear as a mark. This invention solves this problem by applying an adhesive to both sides of the cut flap during pinning on the paper machine, and the two sides are “closed”, essentially making this interface impermeable to water, thereby preventing a water mark. No heating or high temperature curing is required on the paper machine, simplifying the process. This also reduces down time for the customer, and eliminates critical variables that could cause inconsistent results as in the prior art.
Another advantage of this is that the adhesive is not exposed directly to surface wear and abrasion. Additionally, all the work can be done from the sheet side during pinning, resulting in a very practical advantage for speed and safety on wide paper machines.
This combination of belt seam cut flap, which is a result of the nonwoven barrier layer 110 preventing resin penetration into the loops, and application of chemical adhesive applied to the seam of flap side during pinning, provides a consistent, cost-effective, less sheet market prone, and functional improvement for seam process paper machine belts.
In another embodiment, when the surface resin material is a thermoplastic material, heat can be applied to the closed flap edges after pinning, in order to thermally fuse the two sides to each other, effectively blocking water flow.
It should be noted that the invention does not require a thermoplastic composite surface, therefore resinous materials or resinous coatings could also be effectively used.
While the present invention has been particularly shown and described with reference to the foregoing preferred embodiments, those skilled in the art will understand that many variations may be made therein without departing from the spirit and scope of the invention as defined in the following claims. This description of the invention should be understood to include all novel and non-obvious combinations of elements described herein, and claims may be presented in this or a later application to any novel and non-obvious combination of these elements. The foregoing embodiments are illustrative, and no single feature or element is essential to all possible combinations that may be claimed in this or a later application. Where the claims recite “a” or “a first” element or the equivalent thereof, such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements.

Claims

1. A process belt with on-machine seaming comprising:

a barrier layer, wherein the barrier layer protects a predetermined seam loop area from contamination.

2. The process belt of claim 1:

wherein the barrier layer prevents significant contamination of batt fibers into the seam loop area.

3. The process belt of claim 1:

wherein when an additional material is applied to the press fabric, the barrier layer prevents the additional material from contaminating the seam loop area.

4. The process belt of claim 1:

wherein the barrier layer is at least one of a thermoplastic resin, a solid film polyester plastic, solid plastic film, fibrous batt, and a tape.

5. The process belt of claim 1:

wherein the barrier layer has greater density than a surrounding batt structure.

6. A process belt comprising:

a woven base fabric;

a barrier on an upper surface of the base fabric;

a fibrous batt layer on the barrier and needled through the barrier and into the base fabric forming a composite structure; and

an additional material;

wherein the barrier protects a predetermined seam loop area from significant contamination by at least one of fibrous batt material in the fibrous batt layer and the additional material.

7. The process belt of claim 6:

8. The process belt of claim 6:

wherein the barrier layer has greater density than the surrounding batt structure.

9. The process belt of claim 6:

wherein the process belt is an on-machine seamable fabric.

10. The process belt of claim 6:

wherein the additional material is a thermoplastic resin.

11. The process belt of claim 6:

wherein the barrier layer is at least one of a spunbond and a carded nonwoven.

12. The process belt of claim 11:

wherein the barrier layer further comprises a hydrophobic treatment.

13. The process belt of claim 6:

wherein the barrier layer has a thickness of approximately 1-5 mils.

14. The process belt of claim 6:

wherein the barrier layer has a thickness of approximately 2-4 mils.

15. The process belt of claim 6:

wherein the process belt is a press fabric.