Patent US4765934A successfully refreshed from Google Patents.
US4765934A
Expired / Lapsed
US
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Polystyrene bead expansion process
Assignee: DOMINION ALCHROME Corp A Co OF CANADA
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Filing: 1987-08-19
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Granted: 1988-08-23
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Expires: 2007-08-19
Abstract
Abstract Polystyrene beads or beads of other thermoplastic material are expanded to a consolidated foam structure in a hollow cavity of a marine float or other structure by providing the beads with a uniform coating of a saturated brine solution or other aqueous solution of water-soluble salt and exposing the solution to microwave energy to boil the solutioln and thereby heat the beads to cause expansion and fusion to a foam structure.
Inventors
- 👤 Steven E. Nazar
- 👤 Jacob Leidner
- 👤 Ferdinand M. Svirklys
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 06:48
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/22; C08J9/228; C08J9/232; Y; Y10; Y10S; Y10S521/00; Y10S521/915
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
90 words
A method of forming a consolidated foam structure within an enclosed space, which comprises: providing in said enclosed space beads of foamable synthetic thermoplastic polymer capable of expansion to a fully-foamed state and an aqueous solution of a water-soluble salt in the weight proportion of about 25 to about 75 wt. % of the thermoplastic polymeric beads substantially uniformly distributed over the surface of the beads, and applying microwave energy to said aqueous solution to boil the same and cause expansion and cohesion of said beads into a foam structure.
Claim 2
Independent Claim
90 words
A method of forming a consolidated foam structure within an enclosed space, which comprises: providing in said enclosed space beads of foamable synthetic thermoplastic polymer capable of expansion to a fully-foamed state and an aqueous solution of a water-soluble salt in the weight proportion of about 25 to about 75 wt. % of the thermoplastic polymeric beads substantially uniformly distributed over the surface of the beads, and applying microwave energy to said aqueous solution to boil the same and cause expansion and cohesion of said beads into a foam structure.
Claim 3
Dependent Claim
11 words
The method of claim 1 wherein said thermoplastic polymer is polystyrene.
Claim 4
Dependent Claim
20 words
The method of claim 2 wherein said polystyrene beads are in the form of partially-expanded beads capable of further expansion.
Claim 5
Dependent Claim
26 words
The method of claim 1 wherein said aqueous solution of water-soluble salt has a boiling point in the range of about 105° to about 115° C.
Claim 6
Dependent Claim
12 words
The method of claim 4 wherein said water-soluble salt is sodium chloride.
Claim 7
Dependent Claim
24 words
The method of claim 5 wherein said aqueous solution of sodium chloride is uniformly applied to the beads as a saturated aqueous solution thereof.
Claim 8
Dependent Claim
32 words
The method of claim 1 wherein said aqueous solution is spray-applied to the beads during feed thereof into the enclosed space to provide said uniform distribution of aqueous solution on said beads.
Claim 9
Dependent Claim
23 words
The method of claim 7 wherein said aqueous solution comprises about 25 to about 50 wt. % of the weight of said beads.
Claim 10
Dependent Claim
21 words
The method of claim 8 wherein said enclosed space is provided by the interior of a marine float molded from polyethylene.
Claim 11
Dependent Claim
13 words
The method of claim 1 wherein said aqueous solution also contains a surfactant.
Claim 12
Dependent Claim
14 words
A method of claim 1 wherein a proportion of scrap foam also is present.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-08-23 | 1992-02-22 | 1992-08-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-08-23 | 1996-02-22 | 1996-08-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-08-23 | 2000-02-22 | 2000-08-23 | $7700.00 | Window Closed / Lapsed |