Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
1994-03-28
2001-06-19
Kelly, C. H. (Department: 1774)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C428S368000, C428S375000
Reexamination Certificate
active
06248443
ABSTRACT:
TECHNICAL FIELD
The present invention generally relates to a carbon yarn and carbon yarn products. More particularly, the invention relates to a carbon yarn which is flexible after being carbonized. Specifically, the present invention relates to a carbon yarn product which is flexed after pre-carbonizing to break fiber-to-fiber bonds between the yarn filaments.
BACKGROUND OF THE INVENTION
Carbon yarn products are used in many applications such as in the preparation of carbonized fabrics for composite reinforcement and the like. An example of a carbonized fabric is found in U.S. Pat. No. 972,110. Often, a number of carbon-based filaments are bound together such as by twisting, to form a yarn element. Individual yarn elements are then further processed such as by twisting a number of elements to form a cord, or weaving the elements to form a cloth or fabric.
In industries using carbonizable yarn, such as carbonized fabric industries or the like, the first step in manufacturing the carbon yarn is to remove any sizing materials such as starch, mineral oil, wetting agents or “surfactants” or the like, from the raw yarn. This procedure is known as “scouring” and usually includes cleaning the yarn with a dry cleaning solvent such as perchloroethylene or another similar scouring agent. Sizing materials are often applied to carbonizable filaments during the formation of the yarn products to prevent damage during subsequent processing to prepare the yarn. Such subsequent processing may include twisting, spooling, weaving or the like. The sizing material is applied to the yarn product to help prevent damage during such processing.
However, if the sizing is not removed from the carbonizable yarn prior to carbonizing, the resulting carbon yarn product is stiff, brittle, weak and is generally not useable or further processible. This has been determined to be caused, it is believed, by bonding between the individual filaments of the yarn. The bonding is likely caused by the reaction of the sizing material between the filaments during carbonization procedures. The sizing material is present on the raw filaments, and it might be intentionally not removed from the filaments or its removal might be non-uniform. In either case, the resulting carbon yarn product is deficient for the reasons as stated hereinabove.
Unfortunately, perchloroethylene and other scouring solvents have come under scrutiny and regulation, and their use has become increasingly undesirable. A need exists therefore, for a flexible and strong carbon yarn which is prepared without a solvent scouring step.
SUMMARY OF INVENTION
It is therefore, an object of the present invention to provide a strong and flexible carbon yarn and products thereof.
It is another object of the present invention to provide a strong and flexible, rayon-based carbon yarn and yarn products.
It is still another object to provide a process for the preparation of a strong flexible carbon yarn.
At least one or more of the foregoing objects, together with the advantages thereof over the known art relating to carbon yarn, which shall become apparent from the specification which follows, are accomplished by the invention as hereinafter described and claimed.
In general the present invention provides a process for the preparation of a carbon yarn product which comprises the steps of pyrolizing raw carbonaceous yarn comprising a plurality of carbon fibers, at a temperature above about 650° F.; flexing the pyrolized yarn to substantially break fiber-to-fiber bonding between the fibers; and, exposing the yarn to a temperature sufficient to carbonize the carbon.
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DeVane Kenneth A.
Fernandez Ramon B.
Gray J. M.
Hitco Carbon Composites, Inc.
Kelly C. H.
Renner Kenner Greive Bobak Taylor & Weber
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