SEAMING PROCESS FOR PMC FABRIC HAVING MONOFILAMENT YARNS
A seaming process for a PMC fabric includes the steps of: providing a PMC fabric including a plurality of monofilament yarns, at least some of the monofilament yarns having a composition including between approximately 100 to 10,000 parts per million (ppm) of an additive to improve yarn visibility for the fringed ends of an illuminated PMC fabric.
1. Field of the Invention
The present invention relates to paper machine clothing, and more particularly, to seaming processes used to join ends of the clothing in an endless manner.
2. Description of the Related Art
A paper machine clothing (PMC) fabric is typically manufactured with a specific set of design and quality specifications for a particular paper machine's performance requirements. These specifications include surface characteristics, open area, void volume, permeability and smoothness, among others.
Flat woven PMC fabrics are seamed after heat setting to form an endless belt. Seaming is the most time-consuming, costly and tedious part of PMC fabric manufacturing. Weft yarns are raveled out on both ends of the fabric, creating a warp fringe. Warp yarns on both ends of the fabric are then woven together one by one using filling yarn. There are many ways of joining the warp ends together to achieve a desired seam strength. Depending on the strength requirements, the seamed area of the PMC fabric can be several inches long.
After seaming, the PMC fabric is given a final heat set to relieve the stresses in the seaming area. The final heat setting temperature is lower than the preliminary heat setting temperature in order not to alter the properties of the PMC fabric that were set during preliminary heat set. After final heat setting, the fabric edges are trimmed to the paper machine width.
During the seaming process, it is common for much of the weaving to be done by hand. It can be difficult for a person to see the individual yarns such as the exposed warp yarns in the fringe area. When the PMC fabric yarn is composed of darker colored or fine diameter yarns, e.g., fine diameter yarns below 0.25 mm, the exposed warp yarns in the fringe area can be even more difficult to see with the human eye. This compounds the difficulty and expense of the seaming process.
What is needed in the art is a seaming process for a PMC fabric which allows the fringe ends to be more easily woven together.
SUMMARY OF THE INVENTIONThe present invention provides a monofilament yarn for a PMC fabric with an additive that makes the yarn ends easily visible using a light or radiation source. The mechanical properties of the monofilament yarn are not altered by the addition of the additive.
The present invention in one form is directed to a seaming process for a PMC fabric, including the steps of: providing a PMC fabric including a plurality of monofilament yarns, at least some of the monofilament yarns having a composition including between approximately 100 to 10,000 parts per million (ppm) of an additive to improve yarn visibility for the fringed ends of an illuminated PMC fabric.
An advantage of the present invention is that the fringed ends of the fabric can be easily seen under a light or radiation source by a person during the seaming process.
Another advantage of the present invention is that the addition of the additive does not substantially alter the physical properties of the monofilament yarn.
The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:
Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the invention and such exemplifications are not to be construed as limiting the scope of the invention in any manner.
DETAILED DESCRIPTION OF THE INVENTIONReferring now to the drawings, and more particularly to
The composition of the monofilament yarns 12A and 12B include an additive and a thermoplastic resin. In order to more easily see the individual yarns of the PMC fabric during a seaming process, an additive is added during the monofilament yarn making process. This additive makes the yarn easily visible.
More specifically, PMC fabric 10 is formed from a plurality of monofilament yarns 12, for example woven yarns, including an additive, for example a UV additive manufactured by Eastman Chemicals as Eastobrite OB-1™, loading of between approximately 100 to 10,000 parts per million (ppm), for example 1,000 ppm, which makes the fringe at opposite ends of PMC fabric 10 easily visible under black light (which generally emits radiation at wavelengths between approximately 350 nm and 390 nm) while weaving the fringe during a seaming process. The inclusion of an additive is especially useful for fine diameter yarns (below 0.25 mm) and dark colored monofilament yarns (L* value less than 50) which are harder to see with the human eye. A color measurement system, such as CIE L*a*b* or the Yellowness index, can be used to quantify the darkness of the yarn.
A UV additive, also known as an optical brightener (OB) or fluorescent whitening agent absorbs the short wavelength electromagnetic radiation from a radiation source, such as a black light having a wavelength e.g., between approximately 300 nm and 400 nm, which is invisible to the human eye and converts it into visible light of a longer wavelength, for example between approximately 400 nm and 500 nm, which is emitted either as violet, blue or greenish blue light. This principle is generally illustrated in
Fluorescent whitening agents are compounds that are excited or activated by wavelengths in the near-UV range, for example having a wavelength between approximately 360 nm and 365 nm, and then emit light in the blue range, for example having a wavelength between approximately 400 nm and 440 nm. Electrons in fluorescent molecules are excited into a higher energy state by absorption of light, which then emit a small amount of heat plus fluorescence as the electrons return to their ground state.
A sample PET monofilament yarn without a UV additive was compared with a PET monofilament yarn including a UV additive. Table 1 shows some of the physical properties of the PET monofilament used for a PMC Dryer Fabric. The control sample (with no UV additive) is shown in the first column and the properties of the yarn with the UV additive, 1000 ppm loading, are shown in the second column. Table 1 shows that the physical properties of the yarn with the UV additive are substantially the same as the PET monofilament without the UV additive. Therefore, it is clear that the UV additive according to the present invention does not substantially alter the physical characteristics of the monofilament yarn.
During the manufacture of PMC fabric 10, a screw extruder is used to melt blend a mixture of thermoplastic resin (preferably PET) and a UV additive, for example a stilbene. (
During a seaming process of the present invention, a PMC fabric is provided which includes a plurality of monofilament yarns, at least some of which include between approximately 100 ppm to 4,000 ppm of a UV additive. (
During the manufacture of another embodiment of PMC fabric 10, the additive is coated on the yarns rather than incorporated into the composition of the yarns. To that end, a thermoplastic resin (preferably PET) is spun into a filament (
While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.
Claims
1. A seaming process for a paper machine clothing (PMC) fabric, the seaming process comprising the steps of:
- providing a PMC fabric including a plurality of monofilament yarns, at least some of said monofilament yarns having a composition including an additive to improve yarn visibility;
- fringing opposite ends of the PMC fabric by removing filling yarns at the respective opposite ends;
- illuminating the fringed ends of the PMC fabric; and
- weaving together the fringed ends of the illuminated PMC fabric.
2. The seaming process for a PMC fabric according to claim 1, wherein the additive is at least one of a UV additive, an IR additive, and a metal powder additive.
3. The seaming process for a PMC fabric according to claim 1, wherein said plurality of monofilament yarns include a plurality of warp yarns and a plurality of weft yarns, and all of said warp yarns include said additive.
4. The seaming process for a PMC fabric according to claim 1, wherein at least some of said monofilament yarns include between approximately 100 to 10,000 parts per million (ppm) of an additive.
5. The seaming process for a PMC fabric according to claim 4, wherein at least some of said monofilament yarns include approximately 1,000 ppm loading of said additive.
6. The seaming process for a PMC fabric according to claim 1, wherein the fringed ends of the PMC fabric are illuminated using radiation at a wavelength to make the additive visible.
7. The seaming process for a PMC fabric according to claim 1, wherein said additive is a stilbene.
8. The seaming process for a PMC fabric according to claim 7, wherein said stilbene is 4,4′-bis (benzoxazol) stilbene.
9. The seaming process for a PMC fabric according to claim 1, wherein said PMC fabric includes a plurality of woven yarns.
10. The seaming process for a PMC fabric yarn according to claim 1, wherein said composition further comprises a thermoplastic resin.
11. The seaming process for a PMC fabric yarn according to claim 10, wherein said thermoplastic resin is polyethylene terephthalate (PET).
12. The seaming process for a PMC fabric yarn according to claim 11, wherein said composition has a tenacity which is approximately the same as said PET alone.
13. The seaming process for a PMC fabric yarn according to claim 11, wherein said composition has a relative elongation which is approximately the same as said PET alone.
14. The seaming process for a PMC fabric yarn according to claim 11, wherein said composition has a loop strength which is approximately the same as said PET alone.
15. A seaming process for a paper machine clothing (PMC) fabric, the seaming process comprising the steps of:
- providing a PMC fabric including a plurality of monofilament yarns, at least some of said monofilament yarns being coated with a coating formulation which includes an additive to improve yarn visibility;
- fringing opposite ends of the PMC fabric by removing filling yarns at the respective opposite ends;
- illuminating the fringed ends of the PMC fabric; and
- weaving together the fringed ends of the illuminated PMC fabric.
16. The seaming process for a PMC fabric according to claim 15, wherein the additive is at least one of a UV additive, an IR additive, and a metal powder additive.
17. The seaming process for a PMC fabric according to claim 15, wherein said plurality of monofilament yarns include a plurality of warp yarns and a plurality of weft yarns, and all of said warp yarns include said additive.
18. The seaming process for a PMC fabric according to claim 15, wherein at least some of said monofilament yarns include between approximately 100 to 10,000 parts per million (ppm) of an additive.
19. The seaming process for a PMC fabric according to claim 18, wherein at least some of said monofilament yarns include approximately 1,000 ppm loading of said additive.
20. The seaming process for a PMC fabric according to claim 15, wherein the fringed ends of the PMC fabric are illuminated using radiation at a wavelength to make the additive visible.
21. The seaming process for a PMC fabric according to claim 15, wherein said additive is a stilbene.
22. The seaming process for a PMC fabric according to claim 21, wherein said stilbene is 4,4′-bis (benzoxazol) stilbene.
23. The seaming process for a PMC fabric according to claim 15, wherein said PMC fabric includes a plurality of woven yarns.
24. The seaming process for a PMC fabric yarn according to claim 15, wherein said composition further comprises a thermoplastic resin.
25. The seaming process for a PMC fabric yarn according to claim 24, wherein said thermoplastic resin is polyethylene terephthalate (PET).
26. The seaming process for a PMC fabric yarn according to claim 25, wherein said composition has a tenacity which is approximately the same as said PET alone.
27. The seaming process for a PMC fabric yarn according to claim 25, wherein said composition has a relative elongation which is approximately the same as said PET alone.
28. The seaming process for a PMC fabric yarn according to claim 25, wherein said composition has a loop strength which is approximately the same as said PET alone.
Type: Application
Filed: Jul 6, 2011
Publication Date: Jan 10, 2013
Inventors: Ashish Sen (Summerville, SC), Jürgen Abraham (Nattheim), Brian Good (Summerville, SC)
Application Number: 13/177,084
International Classification: D06H 5/00 (20060101); D03D 3/04 (20060101); D03D 15/00 (20060101);