Plastic and nonmetallic article shaping or treating: processes – Direct application of fluid pressure differential to... – Producing multilayer work or article
Reexamination Certificate
1999-02-16
2001-10-09
Dye, Rena L. (Department: 1772)
Plastic and nonmetallic article shaping or treating: processes
Direct application of fluid pressure differential to...
Producing multilayer work or article
C264S254000, C264S259000, C264S271100
Reexamination Certificate
active
06299820
ABSTRACT:
FIELD OF THE INVENTION
The instant invention is directed to a method of making a pressure vessel using an overmolding process in which a polyolefin is overmolded onto a polyolefin; and the pressure vessel made thereby.
BACKGROUND OF THE INVENTION
Pressure vessels made with polyolefin housings are known. See: “LIQUI-CEL® Extra-Flow 4″×28″ Membrane Contactor For Process Scale” 1994 Product Bulletin. The housings of these vessels, however, must be machined to create the flanges to which the end caps are secured. Machining of the housings is expensive. A less expensive method for the production of the housings is necessary.
The overmolding process is known. See: U.S. Pat. No. 5,409,655; French Patent No. 2,550,848; and Rohner, M. L. “Injection Weldable Nylons” Society of Plastics Engineers, Inc. Rochester, N.Y., Sep. 15-16, 1993. Typically, in an overmolding process, an elastomer is overmolded onto a substrate (the substrate may be made of metal or rigid plastic). In U.S. Pat. No. 5,409,655, KRAYTON®, a thermoplastic elastomer sold by Shell Oil Company of Houston, Tex., is overmolded onto NORYL®, a modified nylon material sold by General Electric Company of Fairfield, Conn. In French Patent No. 2,550,848, a thermoplastic elastomer (an elastomer based on polypropylene and an ethylene-propylene copolymer) is overmolded onto a polypropylene. In the Rohner article, injection welding grade nylons are overmolded onto nylons.
It is believed by some in the plastic's industry that overmolding of a polyolefin (i.e., the overmolded material) onto a polyolefin (i.e., the substrate or also referred to as an insert) is not possible because a melt interface between the two parts can not be formed without overheating and thereby distorting (e.g., warping or caving in) the substrate. Accordingly, there is a need for a process by which a polyolefin can be overmolded onto a polyolefin substrate.
SUMMARY OF THE INVENTION
A method for overmolding a polyolefin onto a polyolefin substrate and for making a pressure vessel includes the steps of:
providing a polyolefin substrate;
placing the substrate into a mold;
supporting the substrate to prevent distortion;
injecting an unfilled polyolefin into a mold and over a surface of the substrate; and
releasing an overmolded part from the mold.
A pressure vessel includes: a polyolefin extruded tube; a polyolefin flange overmolded onto said tube; and a cap engaged to said flange.
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patent: 5582238 (1996-12-01), Plaschkes
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“LIQUI-CEL® Extra-Flow 4″×28″ Membrane Contractor For Process Scale” 1994 Product Bulletin.
Rohner, M.L. “Injection Weldable Nylons” Society of Plastics Engineers, Inc. Rochester, NY, Sep. 15-16, 1993.
Celgard Inc.
Dye Rena L.
Hammer III Robert H.
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