Application of Chapman

• Decision Date: 17 March 1966
• Docket Number: Patent Appeal No. 7412.
• Citation: 357 F.2d 418,148 USPQ 711
• Parties: Application of Wilbur F. CHAPMAN and John N. Cosby.
• Court: U.S. Court of Customs and Patent Appeals (CCPA)

148 USPQ 711, 357 F.2d 418 (1966)

Application of Wilbur F. CHAPMAN and John N. Cosby.

Patent Appeal No. 7412.

United States Court of Customs and Patent Appeals.

March 17, 1966.

Elizabeth Hunter, Morristown, N. J., George B. Campbell, New York City, Arnold B. Christen, Washington, D. C., for appellants.

Clarence W. Moore, Washington, D. C., (Raymond E. Martin, Washington D. C., of counsel), for Commissioner of Patents.

Before WORLEY, Chief Judge, and RICH, MARTIN, SMITH and ALMOND, Judges.

RICH, Judge.

This appeal is from the decision of the Patent Office Board of Appeals affirming the examiner's rejection of product claims 1 to 4 and process claims 5, 6 and 8 in application serial No. 819,106, filed June 9, 1959, for "High Strength Chlorinated Polyethylenes and Process for Preparing Them." No claim is allowed.

Appellants invented improvements in the art of chlorinating polyethylenes. Their application points out that while it is known to chlorinate polyethylenes having a wide variety of structures and molecular weights to obtain resins useful in many applications, such prior art chlorinated polyethylenes are "generally lacking in the high strength characteristics required for the purposes served by the more expensive, rubber like, thermoplastic resins of the polyvinyl and polyvinylidine chloride types." This lack has been due, according to appellants, in part to an inherent lack of these properties in the polyethylene materials chlorinated and in part to degradation of the polyethylene molecules during chlorination, resulting in products of low molecular weights.

According to appellants' brief, by the "combined factors of using as starting materials high molecular weight polyethylenes which themselves have high tensile strengths, and subjecting these polyethylenes to chlorination under such conditions as to minimize molecular weight degradation and consequent loss of strength characteristics" appellants have produced chlorinated polyethylenes alleged to possess "outstandingly high tensile strength characteristics * * *, rendering the resulting products useful in the production of films, coatings, floor coverings and wall coverings of high strength and durability." Appellants emphasize the importance of maintaining the rate of chlorination "within relatively narrow limits" to minimize molecular weight degradation.

Claims 1 and 5, to the product and process, read:

1. A chlorinated polyethylene resin having a chlorine content between about 25% and about 65% by weight, molecular weight characteristics such that its intrinsic viscosity as measured in o-dichlorobenzene at 100°C. is not less than about 1.8, chemically inert, insoluble in organic solvents at 20-25° C., having a tensile strength value according to ASTM method D-638-58T of at least about 3,000 and equal to at least about 100 times the weight percent chlorine in the resin, having a true ultimate tensile value of at least about 8,000, and having an infrared spectrogram showing characteristic absorption peaks at the following wave length: 3.42 to 3.5 microns; 3.38 to 3.48 microns; 6.8 to 6.9 microns; and at 7.8 to 7.9 microns.

5. A process for producing chlorinated polyethylene resins of high strength characteristics which comprises contacting, in finely divided porous powder form, a polyethylene having a weight average molecular weight between about 1,000,000 and about 5,000,000, density between about 0.935 and about 0.985, with a chlorine-containing gas containing chlorine and an inert gas in a ratio of not less than about 0.5 part of inert gas per part of chlorine by weight, at temperatures between about 40°C. and about 100°C., and continuing the contacting until the resulting chlorinated product contains between about 25% and about 65% chlorine by weight, said conditions of temperature, chlorine to inert gas ratio and degree of chlorination being so correlated that the rate of chlorination in terms of weight gain per hundred unit weights of reacting charge per hour is between about 0.5 and about 15.0.

Claims 2, 3 and 4 are dependent on claim 1 and recite further limitations such as an absorption peak at 13.88 microns (claims 2 and 3), a narrower range of chlorine content in the resinous products (claim 2), an intrinsic viscosity range between about 4.0 and about 3.0 (claim 2), higher lower limits for tensile strength and ultimate tensile strength (claim 2), intensity values for certain absorption peaks (claim 3), and the existence of the resin in "particulate form" (claim 4), the particles having densities within a range of about 1.15 and about 1.65.

Claim 6 is dependent on claim 5 and calls for maintaining the temperature between about 40°C. and about 50°C. until the chlorine content is between about 20% and about 30% and then raising the temperature and maintaining it between about 60°C. and about 90°C. until a chlorine content of about 45% to about 65% has been reached.

Claim 8 is independent and defines a method for producing a chlorinated polyethylene having the chlorine content and strength characteristics of the resin defined by claim 2, by a process such as that defined by claim 5.

The references relied on are:

                  Hoerger et al.    2,913,449    Nov. 17, 1959
                  Noeske            2,928,819    Mar. 15, 1960
                

Noeske is entitled "Process for the Chlorination of Polyethylene" and discloses a process for treating solid, powdered, low molecular weight (i. e., about 100,000 to about 300,000) polyethylene, at temperatures up to about 110°C., with gaseous chlorine diluted, if desired, with inert gases. Noeske admixes a pulverulent inert-to-chlorine material such as magnesia, anhydrous magnesium sulfate, anhydrous aluminum sulfate, anhydrous sodium sulfate, or sodium chloride, with the powdered polyethylene prior to chlorination, thereby permitting the use of higher reaction temperatures and consequent shorter reaction times, without entailing the risk of charring the product because of the evolution of excessive heat. Noeske says that prior to his work is had been difficult to obtain products having a chlorine content above about 40% by weight because extremely long chlorination periods were required. The degree of chlorination disclosed by Noeske ranges from 52% in example 1 to 69% in example 6. The actual temperatures employed range from 50°C. in example 7 to 105°C. in example 6. In six of Noeske's eight examples, a constant weight ratio of nitrogen to chlorine of 0.4 is employed; and, in the other two, a nitrogen to chlorine ratio by weight ranging initially from 2.0 to 0.5 after five hours is used. The highest per cent chlorination at the end of this period appears to be about 32, the reaction temperature being about 65°C. throughout.

Hoerger discloses a process for chlorinating a high molecular weight polyolefin by a so-called "conjoint halogenation technique." Finely divided powdered polyethylene sequentially undergoes "direct" chlorination with a mixed stream of chlorine and nitrogen, this step ordinarily being employed first, and a "solution chlorinating" step. The chlorination of polyethylene, polypropylene, polybutylene, and other polyolefins having linear, unbranched molecular structures is disclosed, such starting materials having molecular weights "usually from at least 40,000 to as much as 500,000 and 3,000,000 and greater." Specifically disclosed is the direct chlorination of polyethylene, "especially that having a relatively high molecular weight of from 40,000 to 500,000 and greater * * * by subjecting the agitated, free-flowing mass of polymer to an atmosphere of chlorine at a temperature between about room temperature and about 85°C." to provide a product having "any desired halogen content to as great as about 80 percent or more by weight * * *."

It is unnecessary to discuss Hoerger's "solution chlorination" process beyond noting that chlorinated polyethylenes obtained by such a process have "a more uniform distribution of the substituent chlorine atoms along the polymer molecule" than is usually the case, and also have "greater elongations and elasticities than may be obtained in products chlorinated by other methods."

The Process Claims

The examiner's position is thus stated in his answer:

Noeske shows all of the features of the process claims, except for the molecular weight of the starting polyethylene. With respect to said starting materials, Noeske contemplates treating polyethylenes prepared by the Ziegler process (column 1, lines 41-50) which process is known to produce polyethylenes of the claimed density. The molecular weights are not held to be critical by Noeske and the highest molecular weight shown is 300,000 (Example 8) apparently determined viscosimetrically as in Example 1. In Example 8, (compared with claim 5 on appeal) the powdered (see claim 1) polyethylene is treated at 80°C. for 12 hours with a gas containing chlorine and initially 5 parts by volume of nitrogen per volume of chlorine or about 2 parts by weight. Based on the table at column 4 lines 15-19, the rate of chlorine addition is on the order of 4% per hour during the first 12 hours. At the end of 12 hours the chlorine content is 43% and at 20 hours 61%, both contents falling within the scope of applicants\' claim 5. Claim 6 which requires the initial

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