US4704239A
Expired / Lapsed
US
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Process for the production of expanded particles of a polymeric material
Assignee: JSP Corp
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Filing: 1985-04-24
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Granted: 1987-11-03
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Expires: 2005-04-24
Abstract
Abstract A process is disclosed for the production of expanded particles of polymeric material wherein unexpanded particles of the material are contacted with a nitrogen-containing inorganic gas under a first pressure condition to impregnate the particles with the gas. The gas impregnated particles are heated to a temperature higher than the softening point of the material, and dispersed into a liquid medium. The resulting dispersion is subjected to a lower pressure to expand the particles. The expanded particles may be used as prefoamed particles for the molding of foamed articles.
Inventors
- 👤 Shohei Yoshimura
- 👤 Toru Yamaguchi
- 👤 Masato Kanbe
- 👤 Hideki Kuwabara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 01:59
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/16; C08J9/18; B; B29; B29C; B29C44/00; B29C44/34; B29C44/3461; C08J9/04; C08J9/12; C08J9/122; C08J2203/00; C08J2203/06; C08J2323/00; C08J2323/02; Y; Y10; Y10S; Y10S264/00; Y10S264/05; Y10S264/09; Y10S264/13; Y10S264/15; Y10S264/16
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
110 words
A process for the production of expanded particles, comprising the steps of: (a) providing unexpanded particles formed of a semicrystalline polymeric material; (b) contacting a nitrogen-containing inorganic gas with the unexpanded particles under a pressurized condition to impregnate the unexpanded particles with said gas, heating the unexpanded particles to a first temperature higher than the softening point of the polymeric material and dispersing the unexpanded particles in a liquid dispersing medium, so that a dispersion maintained at a first pressure and containing the softened, gas-impregnated, unexpanded particles is obtained; and (c) subjecting said dispersion to a second pressure lower than said first pressure so that the unexpanded particles are expanded.
Claim 2
Dependent Claim
110 words
A process for the production of expanded particles, comprising the steps of: (a) providing unexpanded particles formed of a semicrystalline polymeric material; (b) contacting a nitrogen-containing inorganic gas with the unexpanded particles under a pressurized condition to impregnate the unexpanded particles with said gas, heating the unexpanded particles to a first temperature higher than the softening point of the polymeric material and dispersing the unexpanded particles in a liquid dispersing medium, so that a dispersion maintained at a first pressure and containing the softened, gas-impregnated, unexpanded particles is obtained; and (c) subjecting said dispersion to a second pressure lower than said first pressure so that the unexpanded particles are expanded.
Claim 3
Dependent Claim
15 words
A process as claimed in claim 1, wherein said polymeric material is a polyolefin resin.
Claim 4
Dependent Claim
17 words
A process as claimed in claim 1, wherein said nitrogen-containing inorganic gas is air or nitrogen gas.
Claim 5
Dependent Claim
23 words
A process as claimed in claim 1, wherein said liquid dispersion medium is water, ethylene glycol, glycerin, methanol, ethanol or a mixture thereof.
Claim 6
Dependent Claim
14 words
A process as claimed in claim 1, wherein said liquid dispersion medium is water.
Claim 7
Dependent Claim
32 words
A process as claimed in claim 1, wherein said liquid dispersion medium is used in an amount of at least 1.5 parts by weight per part by weight of the unexpanded particles.
Claim 8
Dependent Claim
20 words
A process as claimed in claim 1, wherein step (b) is performed in the presence of finely divided solid particles.
Claim 9
Dependent Claim
33 words
A process as claimed in claim 7, wherein said finely divided solid particles are finely divided particles of aluminum oxide, titanium oxide, basic magnesium carbonate, basic zinc carbonate, calcium carbonate or urea-formaldehyde resins.
Claim 10
Dependent Claim
94 words
A process as claimed in claim 1, wherein said first temperature is one between temperatures 30° C. lower and 40° C. higher than the melting point of the polymeric material when the polymeric material is a non-crosslinked crystalline polymeric material, between temperatures 20° C. lower and 120° C. higher than the melting point of the polymeric material when the polymeric material is a crosslinked, crystalline polymeric material, and between temperatures 10° C. higher and 120° C. higher than the melting point of the polymeric material when the polymeric material is an amorphous polymeric material.
Claim 11
Dependent Claim
17 words
A process as claimed in claim 1, wherein said first pressure is at least 20 atm (absolute).
Claim 12
Dependent Claim
35 words
A process as claimed in claim 1, wherein step (b) is performed in the presence of an impregnating aid capable of plasticizing the polymeric material and having a boiling point of -50° to 200° C.
Claim 13
Dependent Claim
35 words
A process as claimed in claim 11, wherein the impregnating aid is acetone, toluene, xylene, heptane, ethyl ether, dioxane, methyl acetate, ethyl acetate, tetrahydrofuran, a styrene monomer, an isoprene oligomer, dipentene or a mixture thereof.
Claim 14
Dependent Claim
32 words
A process as claimed in claim 11, wherein the impregnating aid is used in an amount of 0.5 to 30 parts by weight per 100 parts by weight of the unexpanded particles.
Claim 15
Dependent Claim
32 words
A process as claimed in claim 1, wherein, in step (b), the unexpanded particles are also contacted with an organic blowing agent for impregnation therewith in addition to the nitrogen-containing inorganic gas.
Claim 16
Dependent Claim
34 words
A process as claimed in claim 14, wherein the organic blowing agent is used in an amount of 2 to 200 parts by weight per 100 parts by weight of the nitrogen-containing inorganic gas.
Claim 17
Dependent Claim
41 words
A process as claimed in claim 1, wherein step (b) includes dispersing the unexpanded particles in the liquid dispersion medium in a closed contact zone, feeding the nitrogen-containing inorganic gas to the zone, and heating the dispersion to said first temperature.
Claim 18
Dependent Claim
29 words
A process as claimed in claim 16, wherein step (c) includes opening said closed contact zone to discharge the dispersion therefrom to an atmosphere maintained at said second pressure.
Claim 19
Dependent Claim
38 words
A process as claimed in any one of claims 1 through 15, wherein the polymeric material is a non-crosslinked polypropylene resin and the unexpanded particles to be expanded in step (c) contain secondary crystals of the polypropylene resin.
Claim 20
Dependent Claim
99 words
A process as claimed in claim 18, wherein step (b) includes dispersing the unexpanded particles in the liquid dispersing medium in a contact zone, maintaining the dispersion at a second temperature which is lower than the first temperature and for a period of time so that the secondary crystals of the polypropylene resin are formed, then heating the dispersion to said first temperature and feeding the nitrogen-containing inorganic gas to said zone while preventing the secondary crystals from being completely destroyed, whereby the unexpanded particles to be expanded in step (c) contains the secondary crystals of the polypropylene resin.
Claim 21
Dependent Claim
24 words
A process as claimed in claim 19, wherein said second temperature is between the melting point and the melt-completion temperature of the polypropylene resin.
Claim 22
Dependent Claim
17 words
A process as claimed in claim 20, wherein the first temperature is higher than the melt-completion temperature.
Claim 23
Dependent Claim
91 words
A process as claimed in claim 18, wherein step (b) includes dispersing the unexpanded particles in the liquid dispersing medium in a closed contact zone, feeding the nitrogen-containing inorganic gas to the zone, heating the dispersion to said first temperature which is between the melting point and the melt-completion temperature of the polypropylene resin, and maintaining the dispersion at said first temperature for a period of time sufficient to form the secondary crystals of the polypropylene resin, whereby the unexpanded particles to be expanded in step (c) contains the secondary crystals.
Claim 24
Dependent Claim
26 words
A process as claimed in claim 18, wherein the non-crosslinked polypropylene resin is a random copolymer having a propylene content of at least 50 weight %.
Claim 25
Dependent Claim
21 words
A process as claimed in claim 23, wherein the random copolymer is a propylene-ethylene random copolymer or a propylene-butene random copolymer.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-11-02 | 1991-05-04 | 1991-11-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-11-02 | 1995-05-04 | 1995-11-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-11-02 | 1999-05-04 | 1999-11-03 | $7700.00 | Window Closed / Lapsed |