In re MacArthur

484 F.2d 491, 179 U.S.P.Q. (BNA) 233, 1973 CCPA LEXIS 265

• Court: Court of Customs and Patent Appeals
• Decided: September 13, 1973
• Docket: Patent Appeal No. 8880
• Status: Published

Opinion

RICH, Judge.

This appeal is from the decision of the Patent Office Board of Appeals affirming the rejection of all 11 claims in appellants’ application, serial No. 657,917,¹ filed August 2, 1967, for “Method for the Preparation of Composite Panels of Interfused Expanded Per-lite.” We affirm.

The Invention

Appellants’ invention is a method of making insulating structural panels of expanded perlite. Perlite is volcanic glass which contains silica, alumina, alkali metal oxides as well as small amounts of oxides of iron, calcium, and magnesium, and about 2 to 5% by weight of entrapped water. When per-lite particles are heated to a temperature of about 1600 to 2200° F., the water vaporizes and causes expansion of the perlite, leaving it in an expanded porous state. Interfusion of the expanded particles to form a rigid mass occurs when a mass of expanded particles is heated to a pyroplastic glassy state in the range 1200° F. to 2400° F. To preserve the porosity, appellants add a highly absorbent carrier that is soaked in an aqueous solution of inorganic flux such as sodium silicate. The specification discloses that this “makes a small amount of flux available at the surfaces of the perlite particles which are in contact one with another and in an amount sufficient merely to flux the adjacent surface portions of the perlite particles for interfusion at elevated temperature without collapse of the expanded perlite.” The fusion of the contacting surface portions of the particles concurrently with the expansion caused by vaporization of the entrapped water therein forms a rigid mass or panel with good insulating properties since the particle porosity is maintained. Claim 1, with reference numerals inserted and read in conjunction with Fig. 1 below, is representative of the claimed process:

1. The method of producing structural panels of expanded perlite inter-bonded by interfusion between the expanded perlite particles comprising the steps of continuously advancing a for-aminous support [22] in one direction, continuously feeding perlite particles admixed with a highly porous, highly absorbent carrier wet with a liquid composition containing a small amount of an inorganic flux, feeding said mixture [16] onto the support to form a substantially uniform endless layer [34] on the surface thereof, heating [by furnace 14] the layer of perlite particles from the top side to a temperature in excess of 1200° F. but below 2400° F., drawing [by fan 40] a draft [38] through the layer from the bottom side to draw the heat substantially uniformly and quickly through the layer of perlite particles, continuing to heat the perlite particles for a time sufficient to reduce the perlite par-tides to a glassy pyroplastic state concurrently with the expansion of the perlite particles by release of combined water and to agglomerate the adjacent surfaces of the expanded perlite particles by interfusion between the surfaces of the perlite particles in contact one with the other while in their pyroplastic state whereby the expanded perlite particles become interbond-ed by interfusion into a composite structure [slab 18] of expanded per-lite.

Appellants do not separately argue the patentability of dependent claims 2-11 other than by commenting that:

Best results can be obtained when the carrier is a cellulosic material as set forth in claim 5, such as sawdust as set forth in claim 6, which generates the controllable amount of heat to provide uniform temperatures throughout the perlite layer and which, when burned from the perlite layer, leaves voids in the perlite layer, further contributing porosity to the continuous expanded perlite panel.

The Prior Art

The references are:

Greenawalt 1,786,714 Dec. 30, 1930

Parsons 2,341,059 Feb. 8, 1944

Stafford et al.

(Stafford) 2,521,190 Sept. 5, 1950

Perlite, The Wonder Material, Page Converter Company (referred to as "Perlite Article"), Sept. 23, 1949

Greenawalt relates to an apparatus and process for making a lightweight porous mass of fused clay balls that are “approximately the size of a pea.” The process involves coating the moist particles of the mass with a “pulverized fuel” and placing the mass on the grate of a sintering pan. The fuel is ignited and air is drawn through the mass by fans to support the combustion of the fuel. The heat hardens the particles and results in the loss of occluded gases in the balls leaving them “highly porous” while simultaneous fusion occurs at the surface of the balls, causing them to be cemented together in the mass. The resulting mass is crushed and used as an artificial concrete or mortar material in place of crushed stone, gravel, and sand.

We described Parsons in an earlier opinion, In re Garnero, 345 F.2d 589, 590, 52 CCPA 1370, 1371, a case involving one of the present appellants, as follows:

Parsons discloses the production of lightweight, porous, ceramic materials for insulating by passing ceramic particles through a high temperature zone and then fusing the particles in a collecting zone to form a composite structure. Ceramic material such as clay is ground into particles and passed through a furnace. According to the reference:

“The temperature of the furnace and the time allowed for the particles to remain therein are calculated to allow the surfaces of the individual particles to come into a fused or molten state. * * * The particles are collected in a zone of the furnace in a mass, each particle adhering to one or more of the others by virtue of their respective fused surfaces.”

Porosity may be obtained by expansion of gas within the particles. Thus,

“ * * * a combustible material such as sawdust, naphthalene, or other organic material is incorporated into the molded clay mass. The combustible material is then burned out during the firing, and voids are left in the product. Gas-liberating substances are also sometimes incorporated with the clay in order to lend porosity to the resulting product. * * * ”

Parson further states:

“In order further to increase the space between the particles, the addition of fluffing agents such as asbestos or mineral wool, cyanite, and the like is also within the scope of this invention. The fluffing agents may act to further separate the particles either by holding the particles apart mechanically or by liberating gas during the formation of the porous mass, thus increasing the size of the voids between the particles. * * * For low temperature work, asbestos or mineral wool works very satisfactorily. * * * Other suitable mineral fluffing agents are vermiculite * * * and silica, the latter preferably at or above 500° C., at which temperature it has an expanding effect. Gas-producing or gas-liberating materials such as gypsum may be incorporated into the dry mix which, when exposed to the high temperature, will volatilize and form cellular structures within the mass.

“Furthermore, to accelerate the softening of the surfaces and subsequent bonding action, a flux which is easily vaporizable, such as sodium chloride, may be introduced into the furnace * * * ”

Stafford and the Perlite Article— which article is also discussed in In re Garnero, supra — relate to two types of furnaces for expanding perlite particles. These two references disclose that per-lite can be expanded when heated in the temperature range 1500° F. to 2100° F. and 1500° F. to 2200° F., respectively. Stafford discloses the use of a thin layer of fused and expanded perlite particles on the furnace wall to serve as an insulating lining. A water-cooled scraper limits build up of the layer on the wall.

The Rejection

The board’s characterization of the differences between Greenawalt and the invention defined by claim 1, with which appellants agreed, reads as follows:

The principal claim * * * differs from Greenawalt essentially in the use of perlite instead of the various “ar-gillaceous materials” of the reference. It also differs in specifying a temperature range, which is that in which the perlite particles are expanded and plasticized, and in requiring the use of “an inorganic flux” in the preliminary wetting of the perlite particles.

The board held that notwithstanding these differences, Parsons, Stafford, and the Perlite Article, considered with Greenawalt, would have made the claimed subject matter obvious within the meaning of 35 USC 103.

OPINION

Appellants argue that the treatment of the non-expansible clay balls of Greenawalt is “clearly dissimilar and unrelated to the treatment of expansible perlite.” They further contend the use of flux and sawdust by Parsons “does not suggest the use of a carrier wet with a liquid containing flux to facilitate uniform expansion of a layer of particles over the cross-section of the layer.”

With regard to appellants’ first argument, Stafford discloses that:

The temperatures and rate of perlite feed within the combustion chamber are controlled to effect heat softening and rapid expansion or puffing of the softened perlite particles while they are in suspension in the combustion gases. The apparatus is further designed to effect rapid removal of the gas suspension of expanded perlite from the high temperature zone and cooling thereof to harden the expanded cellular product.

Whenever flash heat expansion of perlite takes place while the particles are suspended in a flowing stream of hot gas within a furnace, some of the expanded particles are thrown into contact with the wall lining of the furnace while in heat softened condition, and such particles tend to adhere to the lining and to build up thereon so long as the heat expanding operation proceeds.

The insulating lining on the furnace wall is further described as “consisting of low density heat expanded perlite.” Greenawalt is likewise concerned with forming a composite of interfused particles having voids between the particles which are “highly porous” due to the escape of occluded gases at the same time fusion occurs. Greenawalt also discloses the step of drawing a blast of air through his mass of clay particles to facilitate fusion throughout the mass. It is thus apparant that the similarities between the two materials for the purpose of making a lightweight porous insulator of fused particles would have been recognized by one of ordinary skill in the art, and we agree with the board that any differences between clay and perlite, such as the concurrent expansion and fusion of the perlite, would not have been sufficient to make appellants’ claimed process unobvious.

We also think that the disclosure of Parsons would suggest use of sawdust along with flux to facilitate fusion of the particles in the modified Greenawalt process. Appellants’ method of using the flux and “carrier” (sawdust) apparently differs from that of Parsons in that the reference does not disclose using the flux in an aqueous solution. This arguable difference appears to involve no more than an obvious matter of choice in the manner of using the flux and is not demonstrated to provide any unexpected result or advantage..

For the foregoing reasons, the decision of the board is affirmed.

Affirmed.

1 . This application is stated to be a continuation-in-part of application serial No. 524,926, filed February 3, 1966, which was a continuation-in-part of application serial No. 57,171, filed September 20, 1960.