Board of Patent Appeals and Interferences
Patent and Trademark Office (P.T.O.)
*1 EX PARTE DAVID T. RASKE AND JOHN E. YOUNG
Appeal No. 92-3927
April 29, 1993
Application for Patent filed January 3, 1990, Serial No. 07/460,531. Extended-Life Polyethylene Gas Distribution Pipe.
Thomas W. Speckman et al. for appellants
Supervisory Patent Examiner--Joseph L. Schofer
Examiner--R. Delmendo.
Before Pellman, Winters and Steiner
Examiners-in-Chief
Examiner-in-Chief
ON BRIEF
This appeal is from the examiner's decision refusing to allow claims 1 and 3 through 17, which are all of the claims remaining in the application.
Claim 1 is representative:
1. Branched polyethylene pipe wherein said branched polyethylene has the properties: weight average molecular weight greater than 200,000; number average molecular weight greater than about 25,000; and 7 and greater alkyl branches per 1,000 backbone carbon atoms, each said alkyl branch having 4 and greater carbon atoms.
The references relied on by the examiner are:
Billmeyer, Textbook of Polymer Science, Third Edition, pages 364 and 365 (1984).
Ishikawa et al. (Ishikawa), American Gas Association, "Effect of Molecular Structure of Resin on Long-Term Performance of Polyethylene Gas Pipe", pages 175-183 (1987).
The issue presented for review is whether the examiner correctly rejected claims 1 and 3 through 17 under 35 USC 103 as unpatentable over Ishikawa in view of Billmeyer.
OPINION
We shall sustain this rejection.
Initially, we note the examiner's reference to U.S. Patent Number 4,424,330 issued to Raviola and European Patent Number 109,779 issued to Mitsui Petrochemical Industries. See the examiner's Answer, page 4, first paragraph, where these references are cited to "show the general state of the art". This is improper. The examiner does not cite Raviola or Mitsui in the "listing of the prior art of record relied upon in the rejection of claims under appeal", and the examiner expressly states that "[n]o new prior art has been applied in this examiner's Answer". See the examiner's Answer, page 2, sections (7) and (8). We therefore view the reference to Raviola and Mitsui, at page 4 of the Answer, as an improper effort to bring these references in the "back door". Compare In re Hoch, 428 F.2d 1341, 1342 n. 3, 166 USPQ 406, 407 n. 3 (CCPA 1970) (where reference is relied on to support a rejection, whether or not in a "minor capacity", there would appear to be no excuse for not positively including that reference in statement of the rejection). Raviola and Mitsui are not positively included in the statement of rejection, and we have considered the issue under 35 USC 103 based solely on the evidence contained in Ishikawa and Billmeyer.
FINDINGS OF FACT
Turning now to the merits, we make the following findings of fact:
*2 (1) Branched polyethylene pipe has been used for gas distribution in the United States for over 20 years before the filing of the instant application. See appellants' specification, page 2;
(2) The Ishikawa publication, entitled "Effect of Molecular Structure of Resin on Long-Term Performance of Polyethylene Gas Pipe", discloses that "[t]he most important property for polyethylene gas pipe is long-term performance". See Ishikawa, page 175, column 2;
(3) With respect to long-term performance, Ishikawa suggests that increasing the molecular weight of the branched polyethylene leads to better performance. This suggestion reasonably follows from the disclosure that samples PE-A, PE-B, and PE-C show superior performance compared with samples PE-D, PE-E, PE-F, and PE-G. See appellants' main Brief before the Board, page 5, last paragraph. Samples PE-A, PE-B, and PE-C have a higher molecular weight compared with samples PE-D, PE-E, PE-F, and PE-G;
(4) Ishikawa's suggestion to increase the molecular weight of the branched polyethylene is consistent with and reinforced by the Billmeyer text, page 364. In discussing the physical properties of low-density polyethylene, Billmeyer states that "[a]s molecular weight increases, so do tensile strength, tear strength, low-temperature toughness, softening temperature, impact strength, and resistance to environmental stress cracking [emphasis added];
(5) With respect to long-term performance, Ishikawa suggests that increasing the degree of branching in the whole polymer leads to better performance. This follows because samples PE-A, PE-B, and PE-C show superior performance compared with samples PE-D, PE-E, PE-F, and PE-G. See appellants' main Brief before the Board, page 5, last paragraph. Samples PE-A, PE-B, and PE-C have a higher degree of branching in the whole polymer compared with samples PE-D, PE-E, PE-F, and PE-G;
(6) Ishikawa teaches that comonomer distribution affects the long-term performance of pipes rather than the type of branches. See Ishikawa, page 175, paragraph bridging columns 1 and 2. This means to say, based on research performed by Ishikawa, that the type of branch is not a salient factor and would not have been expected to have a substantial effect on long-term performance;
(7) A person having ordinary skill in the art would have found it obvious to modify conventional branched polyethylene pipe by increasing the molecular weight of the polymer and increasing the degree of branching in the whole polymer, based on teachings found in Ishikawa and Billmeyer;
(8) A person having ordinary skill in the art would have found it obvious to modify conventional branched polyethylene pipe, in the manner described in paragraph (7), with a reasonable expectation of improving long-term performance regardless of the type of branches in the branched polyethylene. See Ishikawa, page 175, paragraph bridging columns 1 and 2;
(9) As stated by the examiner, a person having ordinary skill in the art would have found it obvious to determine the optimum values of result-effective variables known in the art;
*3 (10) Following the guidelines and teachings in Ishikawa and Billmeyer, a person having ordinary skill in the art would have found it obvious to determine the optimum values of weight average molecular weight, number average molecular weight, the degree of branching in the whole polymer, and the type of branches in branched polyethylene pipe. In this manner, a person having ordinary skill in the art would have arrived at the subject matter sought to be patented in claims 1 and 3 through 17 with a reasonable expectation of improving the long-term performance of branched polyethylene pipes;
(11) Our finding in paragraph (10) is based on a separate treatment and consideration of each claim on appeal. Commenting separately on dependent claims 4 and 5, we note that it is conventional in this art to use polymeric material having a density of "about 0.93 to about 0.94 grams/cm@3". For example, Ishikawa discloses samples PE-A through PE-G, and each of those samples possesses a density in that range;
(12) We are mindful of the Constant-Tensile Load (CTL) test described in the instant specification; the CTL data referred to therein; and the chemical/mechanical model based on that data. We find, however, that appellants have not presented objective evidence of non-obviousness in this record which would serve to rebut the prima facie case of obviousness or would address the thrust of the examiner's rejection. For example, appellants have not presented a side-by-side test holding all variables the same except for the type of branches on the polymer backbone. Appellants have not established that the type of branches recited in their claims, which would not have been expected to materially affect long-term performance, do, in fact, give rise to unexpectedly superior results.
CONCLUSION
Based on the foregoing findings of fact, we conclude that the subject matter sought to be patented in claims 1 and 3 through 17 would have been prima facie obvious based on teachings found in Ishikawa and Billmeyer. We also conclude that appellants have not presented objective evidence of non-obviousness, on this record, which would serve to rebut the prima facie case. Accordingly, the examiner's decision refusing to allow claims 1 and 3 through 17 is affirmed.
No time period for taking any subsequent action in connection with this appeal may be extended under 37 CFR 1.136(a). See the final rule notice, 54 F.R. 29548 (July 13, 1989), 1105 O.G. 5 (August 1, 1989).
AFFIRMED
BOARD OF PATENT APPEALS AND INTERFERENCES
Irving R. Pellman
Examiner-in-Chief
Sherman D. Winters
Examiner-in-Chief
Arthur J. Steiner
Examiner-in-Chief
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