Paper making and fiber liberation – Processes and products – Multi-layer waterlaid webs or sheets
Reexamination Certificate
2003-09-02
2004-12-21
Griffin, Steven P. (Department: 1731)
Paper making and fiber liberation
Processes and products
Multi-layer waterlaid webs or sheets
C125S011020, C125S011020, C125S011020, C125S011020, C428S034200, C428S154000, C229S940000
Reexamination Certificate
active
06833055
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to multi-ply paperboard prepared from recycled materials. The invention also relates to methods of making such multi-ply paperboard.
BACKGROUND OF THE INVENTION
Recycled materials are widely used in the manufacture of packaging products. This can be primarily due to the fact that virgin fibers can often be more expensive than fibers obtained from recycled materials. Furthermore, many consumers make purchasing decisions based upon whether a product is provided in a package made from recycled materials. Additionally, many agencies require products purchased for governmental purposes to be packaged using recycled materials.
Paperboard can be used to package a wide variety of materials. In keeping with the need to manufacture packaging materials from recycled materials, recycled paperboard is a desirable objective.
A common type of paperboard prepared from recycled fibers is known as “clay coated newsback” or “CCNB.” CCNB is made by Rock-Tenn Company, Norcross, Ga. CCNB exhibits sufficient dry strength to enable its use as a packaging material. Accordingly, CCNB is commonly used to package materials that are generally stored in a dry state. In particular, dry strength is important, for example, to reduce deformation in the package and to therefore improve machineability of the package. Materials that may be packaged in CCNB include, for example, soap/laundry detergents, dry bakery goods, paper goods, cake mixes, cereal or other dry foods. However, CCNB generally does not exhibit dry strength comparable to virgin paperboard of a similar thickness, a fact that can limit its use in packaging certain products.
In some instances, the strength of a recycled paperboard material, such as CCNB, can be improved by increasing the thickness, or caliper, of the paperboard. However, increasing the thickness of a paperboard product can increase the cost of the packaging material and this additional cost may be passed on to the consumer. Accordingly, it is often not economical to attempt to improve the strength of a packaging material prepared from recycled material by increasing the thickness of the packaging material.
Strong packaging materials may be obtained by utilizing paperboard derived from virgin fiber. Because virgin fibers have not previously been subjected to processing (e.g., refining, pulping, processing, converting) or used in packaging material, such fibers can generally provide strong and durable paperboard packaging materials. However, as noted previously, the cost of virgin fibers can be high. As such, for many packaging applications it is often not economical to prepare paperboard from virgin fibers.
In view of the above, it would be beneficial to have a multi-ply paperboard prepared from recycled fibers that exhibits good strength, in particular dry strength. Also, it would be beneficial to have a multi-ply paperboard prepared from recycled materials that exhibits good machineability. More particularly, it would be desirable to have a multi-ply paperboard prepared from recycled materials that exhibits strength and machineability properties that are comparable to those of paperboard of the same or similar thickness that is prepared from virgin fiber.
SUMMARY OF THE INVENTION
This invention, in one aspect, relates to a multi-ply paperboard having at least three inner plies and, in some aspects, a top liner and/or back liner, wherein one or more plies of the multi-ply paperboard is derived from fiber sources comprising at least about 80% by weight recycled material. The multi-ply paperboard in various aspects of the present invention exhibits strength and/or machineability characteristics comparable to those of paperboard prepared from virgin fiber. In further aspects, the present invention relates to methods of making the multi-ply paperboard of the present invention.
Additional advantages of the invention are set forth in part in the description that follows, and in part will be evident from the description, or may be learned by practice of the invention. Various advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. The foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
The accompanying drawings, which are incorporated in and constitute a part of this document, illustrate several embodiments of the invention and together with the description, serve to explain the principles of the invention.
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Balaguer, Jr. Roberto
Barton Thomas F.
Hansen James K.
Leitinger Jeffrey M.
Munson, Jr. Richard L.
Griffin Steven P.
Hug Eric
Needle & Rosenberg P.C.
Rock-Tenn Company
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