Paper making and fiber liberation – Processes and products – Reclamation – salvage or reuse of materials
Reexamination Certificate
2001-10-09
2003-06-03
Chin, Peter (Department: 1731)
Paper making and fiber liberation
Processes and products
Reclamation, salvage or reuse of materials
C162S125000, C162S127000, C428S304400, C428S311510, C428S311710, C428S311910, C428S314400, C428S318400
Reexamination Certificate
active
06572736
ABSTRACT:
BACKGROUND
1. Field of the Invention
The present invention pertains to low cost moisture resistant and dimensionally stable non-woven continuous webs, and the use of inexpensive furnish for producing such webs.
2. Related Art and Other Considerations
Non-woven continuous web materials have been known in the art at least since the 19
th
Century, when the English papermaking brothers Sealy and Henry Fourdrinier started their first machine. Over the years many fibers have been used to make various types of webs, including asbestos, bagasse, cotton, glass, hemp, jute, kenaf, sisal, various types of wood cellulose pulp, and many forms of synthetic plastic fibers. For example, U.S. Pat. Nos. 3,773,513 and 3,885,962 to MacClaren teach the use of glass fiber and latex to stabilize a photographic paper.
When health concerns made asbestos fiber obsolete, web makers turned to glass fibers and synthetic fibers made of various plastics. For example, common vinyl floor backing webs which had been made with asbestos fibers were subsequently made of a combination of glass and plastic fibers using a polymer latex as a binder. U.S. Pat. No. 4,274,916 and U.S. Pat. No. 4,373,992 both disclose a dimensionally stable backing web using polypropylene fibers for stabilization. U.S. Pat. No. 4,373,992 further teaches the adding of glass fibers. U.S. Pat. No. 4,269,657 pertains to an asbestos-free web that uses slightly refined virgin cellulose fiber incorporating a low percentage of glass fiber.
The art of “sizing” non-woven webs is nearly as old as the continuous formation mode. For the purpose of defining “sizing,” see simultaneously-filed U.S. patent application Ser. No. 09/971,771 and U.S. Provisional Patent application No. 60/238,457 , both entitled “NON-WOVEN WEB HAVING UNIQUE LIQUID RESISTANCE AND DIMENSIONAL STABILITY”, which are incorporated herein by reference in their entirety. Products using the materials of the present invention can be either sized, or not sized. The current invention pertains to types of fiber utilized rather than any form of sizing against moisture resistance.
A sampling of prior art directed toward various different types of fibers used in non-woven webs can be found in the following list of U.S. patents, all of which are incorporated herein by reference:
3,773,513
3,885,962
4,174,415
4,188,355
4,245,689
4,269,657
4,274,916
4,373,992
4,426,470
4,445,972
4,457,785
4,472,243
4,481,075
4,510,019
4,513,045
4,536,447
4,543,158
4,545,854
4,591,412
4,609,431
4,618,401
4,626,289
4,680,223
4,681,658
4,749,444
4,789,430
4,956,049
4,964,954
4,969,975
5,236,757
5,236,778
5,393,379
5,409,574
5,501,771
5,501,774
5,536,370
An ordinary 100% cellulose non-woven continuous web material known as “felt” has been used for many years in the production of asphalt saturated roofing felt. This material is used to cover and protect the plywood or composition board comprising the structural part of a sloped roof prior to adding exterior protection. Sloped roof construction is normally used on residential buildings, churches, and schools. The exterior covering over the saturated asphalt felt can be shingles, tiles, slate, or newer materials such as standing ridge steel panels. The layer of asphalt saturated cellulose felt between the structural deck and exterior membrane is often called “underlayment.”
A particular glass fiber reinforced non-woven continuous web material has been used for many years in the production of polyisocyanurate (polyiso) foam board insulation. This rigid plastic foam insulation board has become the most popular type of commercial roofing insulation. It is manufactured by pouring liquid chemical streams on the continuously moving bottom felt, known as the bottom “Facer,” with a second Facer being placed on top of the foaming streams. The polyiso foaming liquid is deposited between two webs of the Facer felt, cured into a unified foamed board, and then cut into insulation board lengths. The largest producer of this facer felt, Atlas Roofing Corporation, developed a glass fiber-utilizing facer which Atlas refers to as “Glass Reinforced Felt” (GRF) Facer. Certain aspects of this facer product are disclosed in U.S. patent application, Ser. No. 09/425,051, which is incorporated herein by reference in its entirety. The GRF Facer has a higher degree of dimensional stability than 100% cellulose felt. As an integral part of an insulation board, GRF Facer adds strength and durability to a lightweight insulation board that is used in a severe environment. Strength and durability are important because commercial roofing products suffer some of the most intense punishment experienced by building construction products.
Historically, asphalt saturated roofing felt and GRF Facers have primarily used recycled waste paper as the raw material source for fiber. In most cases, OCC (Old Corrugated Container) is the main source of fiber. OCC is normally the highest cost material used in a paper mill that uses nothing but recycled waste paper. Mixed waste, or office waste, or newsprint, or wood flour, or some mixture of these has been the lower cost fiber source to augment the OCC. The successful use of recycled glass fiber has improved the properties of the facer web while keeping the cost reasonable. The cost of either virgin glass fiber or virgin cellulose fiber is much too high for this facer.
For the purpose of describing this invention, the term “Clarifier Sludge” refers to the rejected solids that are separated from the post-processing water by the cleaning and recycling systems in paper and pulp mills. Thus, “Clarifier Sludge” encompasses but is not limited to the mixture of short fibers, extremely large fibers, and inorganic contaminates that are separated from the recycling water of a pulp and/or paper mill. Clarifer Sludge is sometimes sent to an approved landfill. Most of it is burned as boiler fuel after some water has been removed. Several solid/liquid separation systems in use have trade names, but herein they are collectively and generically called “clarifiers.” Both pulp mills and paper mills have a need to clean their post-processing water, especially if it is an effluent going back into the public sewer or watershed systems. Untreated Clarifier Sludge is notoriously unacceptable as a paper mill furnish.
Thus, the owner of the pulp and/or paper mills primarily direct their efforts to the clarification of the water, rather than emphasizing the collection of solids (e.g., Clarifier Sludge). The collection of solids is an onerous but necessary part of the cleaning of pulp and paper mill effluent water. Disposal of Clarifier Sludge is often hampered by environmental concerns. The quality of the fiber found in this recovered solids mass will depend upon the source of the fiber used by the paper mill. If a pulp mill is integrated with a paper mill, these recycling water streams are usually mixed prior to clarifier treatment. In this case, the fiber quality of these mixed streams will be higher than most any other situation. The reason is that some of this fiber has never been through a refiner. Even the relatively high quality Clarifier Sludge from a de-inking plant will have no unrefined fibers. The highest quality sludge is found where a pulp mill treats their own recycling water, separate from a paper mill.
Many attempts have been made at improving wet Clarifier Sludge to a state of being useful. At least by the mid-1970s a company developed a system for recovery of fiber from paper mill effluent. U.S. Pat. No. 3,833,468 to Boniface teaches such a system. Other U.S. patents concentrating on either the apparatus to improve, or the method of improving, waste Clarifier Sludge include the following:
4,983,258
5,002,633
5,137,599
5,297,742
5,332,474
5,423,993
5,527,432
5,536,371
5,772,847
The various processes to improve quality of Clarifier Sludge are relatively expensive, raising the cost of acceptable fiber furnish. In some instances, the freight costs to transport this type of reclaimed fiber are prohibitive. Excessive freight costs can be due to the large percentage of water usu
Blanpied Robert H.
Burkeen Ricky
Bush Philip
Atlas Roofing Corporation
Chin Peter
Nixon & Vanderhye, B.C.
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