US3725317A
Expired / Lapsed
US
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Nucleation of thermoplastic polymeric foams
Assignee: Cupples Container Co
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Filing: 1970-11-30
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Granted: 1973-04-03
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Expires: 1990-11-30
Abstract
Abstract In producing thermoplastic polymeric foams, particularly polystyrene, as by melt extrusion with the aid of a blowing agent, nucleation is accomplished by providing in the thermally plastified polymeric material the combination of an ammonium salt of a carboxylic acid, typically ammonium acetate, a carbonate or bicarbonate, and ammonium chloride. Under conditions of extrusion, for example, the two ammonium salts are thermally decomposed to yield both ammonia, as a nucleating agent, and acidic products which in turn react with the carbonate or bicarbonate to yield carbon dioxide as an additional nucleating agent.
Inventors
- 👤 C Ronden
- 👤 D Roylance
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 22:29
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/0095; C08K; C08K3/00; C08K3/16; C08K3/18; C08K3/24; C08K3/26; C08K5/00; C08K5/04; C08K5/09
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
13 words
The method defined in claim 1, wherein said ammonium carboxylate is ammonium acetate.
Claim 2
Dependent Claim
43 words
The method defined in claim 1, wherein the thermoplastic polymeric material is polystyrene, the ammonium carboxylate is ammonium acetate, and the ammonium acetate and ammonium chloride are each employed in an amount substantially equal to 0.1 percent of the weight of the polystyrene.
Claim 3
Dependent Claim
30 words
The method defined in claim 3, wherein the carbon dioxide liberating material is sodium bicarbonate in an amount substantially equal to 0.2 percent of the weight of the polymeric material.
Claim 4
Dependent Claim
46 words
The method defined in claim 1, wherein the thermoplastic polymeric material is polystyrene, the blowing agent employed comprises a halogenated hydrocarbon and is injected into the thermally plastified material in the intruder, and the extruder is operated at a feed end temperature of at least 500*F.
Claim 5
Dependent Claim
22 words
The method defined in claim 5, wherein the ammonium carboxylate is ammonium acetate, and the carbon dioxide liberating material is sodium bicarbonate.
Claim 6
Dependent Claim
19 words
The method defined in claim 6, wherein the ammonium acetate and ammonium chloride are employed in substantially equal amounts.
Claim 7
Dependent Claim
50 words
The method defined in claim 7, wherein the ammonium acetate and ammonium chloride are each employed in an amount substantially equal to 0.1 percent of the weight of the polystyrene, and the sodium bicarbonate is employed in an amount substantially equal to 0.2 percent of the weight of the polystyrene.
Claim 8
Dependent Claim
65 words
The method defined in claim 1, wherein the thermoplastic polymeric material, the ammonium carboxylate, the ammonium chloride, and the carbon dioxide liberating material are supplied to the extruder in the form of a dry blend, the thermoplastic polymeric material being in particulate form, and the ammonium carboxylate, ammonium chloride and sodium bicarbonate are supported on and adhered to the particles of the thermoplastic polymeric material.
Claim 9
Dependent Claim
92 words
An extrusion composition for the production of foamed polymeric material by melt extrusion, comprising 100 parts by weight of a thermoplastic polymeric material in particulate form, said material being selected from the group consisting of polymers of a styrene, polymers of an olefin, polymers of a halogenated olefin and polyamides; 0.05-0.2 part by weight of an ammonium carboxylate; 0.05-0.2 part by weight of ammonium chloride; and 0.1-0.4 part by weight of a carbon dioxide liberating material selected from the group consisting of the alkali metal and alkaline earth metal carbonates and bicarbonates.
Claim 10
Dependent Claim
14 words
The extrusion composition defined in claim 10, wherein the ammonium carboxylate is ammonium acetate.
Claim 11
Dependent Claim
34 words
The extrusion composition defined in claim 11, wherein the thermoplastic polymeric material is polystyrene, and the ammonium acetate and ammonium chloride are each present in an amount substantially equal to 0.1 part by weight.
Claim 12
Dependent Claim
26 words
The extrusion composition defined in claim 12, wherein the carbon dioxide liberating material is sodium bicarbonate in an amount substantially equal to 0.2 part by weight.
Claim 13
Dependent Claim
28 words
The extrusion composition defined in claim 10, wherein the ammonium carboxylate, ammonium chloride and carbon dioxide liberating material are supported on the particles of the thermoplastic polymeric material.
Claim 14
Independent Claim
265 words
The method for producing polystyrene sheet especially suited for conversion by thermoforming into products having improved strength and rigidity, comprising supplying to an extruder a uniform mixture of polystyrene in particulate form, an ammonium carboxylate in an amount equal to 0.05-0.2 percent of the weight of said polystyrene, ammonium chloride in an amount equal to 0.05-0.2 percent of the weight of said polystyrene, and a carbon dioxide liberating material selected from the group consisting of the alkali metal and alkaline earth metal carbonates and bicarbonates in an amount equal to 0.1-0.4 percent of The weight of said polystyrene, said ammonium carboxylate, said ammonium chloride, and said carbon dioxide liberating material each being in particulate form and of a particle size which is small in comparison with that of said polystyrene; advancing said mixture through the feed end portion of the extruder with a mixing action and there heating the same to a temperature of at least 475*F. to convert the polystyrene to a melt and to cause thermal decomposition of both said ammonium carboxylate and said ammonium chloride, yielding ammonia and acidic products, said carbon dioxide reacting with said acidic products to produce carbon dioxide, the ammonia and carbon dioxide being distributed through the polystyrene melt; injecting into the melt in the extruder a normally liquid, low-boiling blowing agent comprising a major proportion of a halogenated hydrocarbon and a minor proportion of pentane; and further advancing the melt and extruding the same through a sheet-forming die to form foamed polystyrene sheet, said ammonia and carbon dioxide acting as nucleating agents during foaming of the polystyrene.
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) | 1976-04-02 | 1976-10-02 | 1977-04-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-02 | 1980-10-02 | 1981-04-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-02 | 1984-10-02 | 1985-04-03 | $7700.00 | Window Closed / Lapsed |