Appeal No. 1998-1411 Page 5
Application No. 08/562,316
that the binder resin would appear to have the recited Tg of at least 110 /C because it meets the
compositional limitations of the instant claims and has a relatively high molecular weight (Answer, page
4).
The Examiner has presented no documented proof of the Tg levels of the various polymers
described by Hill and Hofmann. We note that the specific polymer described in Appellants’
specification, i.e. a copolymer containing methacrylic acid, methyl methacrylate and ethyl acrylate in a
weight ratio of 22.2/64.6/13.2, weight average molecular weight 45,000 and acid number 130-150, is
different than the exemplified polymers of the references. Our own review of various handbooks2
indicates that the Tgs of acrylic polymers tend to be below 110 /C and the Tg for polymethyl
methacrylate appears to depend on whether the polymer is atactic (Tg 105 /C), syndiotactic (Tg 120
/C) or isotactic (Tg 45 /C)3. Therefore, for a homopolymer of polymethyl methacrylate, it cannot be
2See Zbigniew D. Jastrzebski, The Nature and Properties of Engineering Materials, app.
Table A4 at 615 (2d ed. 1976); Polymer Handbook III-66-69 (J. Brandrup & E. H. Immergut eds.,
2d ed. 1966); Modern Plastics Encyclopedia 513-14 (Rosalind Juran et al. eds. 1988).
3We note that Appellants presented evidence at the Oral Hearing concerning the Tg of
polymethyl methacrylate. As this particular evidence was not in the written record and the Examiner
had no opportunity to address this evidence, we cannot place any weight on it. However, we have
independently cited evidence of the Tg of various acrylic and methacrylic polymers so as to illustrate
why the belief that the Tgs of the prior art polymers are inherently within the claimed range is not
reasonable in this case. While we have performed some limited fact finding, we wish to point out that
the Board of Patent Appeals and Interferences is a board of review and not a vehicle for initial
examination. See 35 U.S.C. § 6(b)(2000). It is incumbent on the Examiner and Appellants to place
into the written record at the appropriate time enough evidence to meet their respective burdens of
production and proof in order to advance the examination of the application.
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