Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Particulate matter
Reexamination Certificate
1999-07-20
2001-04-10
Le, Hoa T. (Department: 1773)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Particulate matter
C162S109000, C162S157600, C162S181800, C428S473500
Reexamination Certificate
active
06214465
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to floor absorbent materials for absorbing water, oil and other liquids from a floor.
BACKGROUND OF THE INVENTION
When paper such as ledger or magazine paper is recycled by first breaking the paper down into a pulp slurry containing its individual components, long cellulose fibers are recovered that are useful for making tissue or other paper products. The slurry also contains a significant amount of other materials including primarily kaolin clay and short cellulose fibers which are not useful for making tissue. In an effort to make the maximum use of materials in the pulp slurry, various products have been developed.
One of the products that has been developed is a granular absorbent product that is made by a process that is known as the KAOFIN process and is described in U.S. patent application Ser. No. 08/852,419, filed May 8, 1997, now U.S. Pat. No. 5,882,480 which is incorporated herein by reference for its disclosure of the process for making absorbent granules. The granular product of this process is described in our copending applications, Ser. No. 08/857,302 filed May 16, 1997 now U.S. Pat. No. 5,807,465; and Ser. No. 08/929,601 filed Sep. 19, 1997, now U.S. Pat. No. 5,888,345 which are incorporated herein by reference for a disclosure of the granular absorbent product made by the KAOFIN process.
Desirable characteristics for granular absorbent products include a high rate of absorption of liquids, a high bulk density, and a high resistance to attrition. For example, U.S. Pat. No. 4,343,751 (the '751 patent) discloses a process for making absorbent pellets from clay that may be used as a floor absorbent. The '751 patent discloses the use of paper sludge in amounts between ten percent and fifty percent of the total mass of the agglomerated solids. However, the absorbency is less than ideal as seen in the examples which include pellets having 50% paper sludge and 50% clay fibers, a bulk density of 38 lbs/ft and only 78% absorbency (see Chart 2, sample 008).
Another example is disclosed in U.S. Pat. No. 5,019,564 (the '564 patent) which is directed to non-clay agricultural granules. The granules are formed by the agitative agglomeration of a plant fiber slurry and resembles a clay granule in all respects except for its chemical inertness.
Clay products, such as those described in the '751 patent, have the disadvantage of low absorbency when mixed with paper sludge, and relatively high attrition rates when the fiber content is low, as described in the '564 patent. When used as a floor absorbent, it is desirable that the granules retain their integrity after absorbing water or oil from the floor.
Another problem encountered with granular floor absorbents is that the granules are generally spherical and tend to roll across the floor. When a worker steps on the granules, there is a danger that the granules will cause the worker to slip and fall as the granules roll under his shoes.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an improved granular absorbent product made from recycled waste paper and having a high absorbency, a high resistance to attrition, and a relatively high bulk density. It is a further objective of the present invention to provide a granular absorbent product that has a bulk density sufficiently high to provide an effective commercial absorbent that can be used to absorb oil and water and other liquids. It is another object of this invention to provide a granular absorbent that resists rolling when stepped on by a worker after it has been spread on the floor to absorb the liquid. Another object of the present invention is to provide a process for making such an improved granular absorbent product.
These objects are accomplished by the present invention which comprises a low fiber content granular absorbent product made from recycled paper and containing kaolin clay and paper fiber. The paper fiber contains less than about 10% by weight of fibers having a length greater than the width of the openings in a 100 mesh screen (0.149 inches) and an absorbency for water of at least 0.90 ml/g and resistance to attrition of at least 99%.
An important feature of this invention is that fibers suitable for papermaking, referred to generally as long fibers, are efficiently removed from the pulp slurry, so that the secondary stream contains a major portion of fibers that are too short for papermaking, referred to generally as short fibers. The procedure utilized for determining fiber length is described in TAPPI method T233 (1995). Using this procedure, it was determined that less than 10% by weight of the fibers in the secondary stream were retained on the 100 mesh (U.S. standard) screen, which has openings of 0.149 mm.
The preferred granular floor absorbent of the present invention is crushable when walked on by a worker and has a coefficient of friction greater than 0.50, but has a resistance to attrition of at least 99%.
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Knapick Edward G.
Willemsen Brent
Wolfer Ernest P.
Burns Doane Swecker & Mathis L.L.P.
Le Hoa T.
Marcel Paper Mills, Inc.
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