Chemistry Reference
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gives examples which illustrate the invention. In this section, sometimes
there are comparative examples of items similar to the invention that can
be used to illustrate the advantage of the inventive examples. The most
important part of the application is the section of claims where the inventor
states what he is claiming as his invention. Often there is a broad claim and
then more limited claims based upon the broad claim. These more limited
claims flowing from a broad claim are called dependent claims because they
depend on an earlier claim.
As an example, consider the first four claims of a recently issued patent [4].
1. A method for processing UHMWPE for use in medical applications; the
method comprising the steps of:
combining UHMWPE with an antioxidant to form a blend having
0.01 to 3.0 weight percent of the antioxidant;
processing the blend to consolidate the blend, the consolidated blend
having a melting point;
preheating the consolidated blend to a preheat temperature below the
melting point of the consolidated blend; and
irradiating the preheated consolidated blend with a total irradiation
dose of between 25 kGy and 1000 kGy while maintaining the con-
solidated blend at a temperature below the melting point of the
consolidated blend to form an antioxidant stabilized crosslinked
UHMWPE blend.
2. The method of claim 1, wherein said combining step further comprises
combining UHMWPE with an antioxidant to form a substantially
homogenous UHMWPE blend having 0.01 to 3.0 weight percent of the
antioxidant.
3. The method of claim 1, wherein said combining step further comprises
mixing the UHMWPE powder with tocopherol by at least one of sol-
vent blending, high shear mixing, precision coating, utilizing a fluidized
bed, atomization, emulsion polymerization, electrostatic precipitation,
wetting or coating of particles, and master batch blending.
4. The method of claim 1, wherein said combining step further comprises
mixing the UHMWPE powder with tocopherol by high shear mixing.
Claim 1 is the broad or independent claim. It claims the invention in its
broadest sense. Claims 2 - 4 are dependent claims depending on claim 1 and
are narrower aspects of the invention of claim 1. Claim 1 requires a consoli-
dated blend but claim 2 requires that it be homogeneous. Claim 3 restricts the
antioxidant of claim 1 to a specific antioxidant, tocopherol. Claim 4 restricts
the claimed invention to both tocopherol and a particular method of mixing.
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