US4448901A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Expanded particles of polyolefin resin and process for producing same
Assignee: Kanegafuchi Chemical Industry Co Ltd
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Filing: 1983-05-13
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Granted: 1984-05-15
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Expires: 2003-05-13
Abstract
Abstract The mixture of water and the polyolefin resin particles impregnated with a volatile blowing agent are released from the interior of the pressure-resistant container under a constant temperature and constant pressure preferably keeping the partial pressure of the blowing agent constant, through at least one orifice having an area of 0.07 to 300 mm2, into a low-pressure zone. This invention gives various advantages when applied to the practical process resulting in expanded particles with superior properties which are free of blocking and remarkably uniform in the degree of expansion, and are useful for molding.
Inventors
- 👤 Kenichi Senda
- 👤 Masao Ando
- 👤 Kyoichi Nakamura
- 👤 Kiyoshi Mori
- 👤 Tatehiko Nishida
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:14
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/16; C08J9/18; B; B29; B29C; B29C44/00; B29C44/34; B29C44/3461; C08J2203/00; C08J2203/14; C08J2203/142; C08J2323/00; C08J2323/02; Y; Y10; Y10S; Y10S264/00; Y10S264/09
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
119 words
A process for producing expanded particles of a polyolefin resin characterized by dispersing polyolefin resin particles 0.25 to 10 mm in particle size and a volatile blowing agent in water in the presence of a dispersant within a pressure-resistant container, heating the mixture at a temperature within the range of from the melting point of crystals of the resin minus 25° C. to the melting point plus 10° C. to impregnate the resin particles with the blowing agent, and releasing the mixture of the particles and water into a low-pressure zone through at least one orifice having an area of 0.07 to 300 mm 2 while maintaining the interior of the container at a constant temperature and constant pressure.
Claim 2
Dependent Claim
119 words
A process for producing expanded particles of a polyolefin resin characterized by dispersing polyolefin resin particles 0.25 to 10 mm in particle size and a volatile blowing agent in water in the presence of a dispersant within a pressure-resistant container, heating the mixture at a temperature within the range of from the melting point of crystals of the resin minus 25° C. to the melting point plus 10° C. to impregnate the resin particles with the blowing agent, and releasing the mixture of the particles and water into a low-pressure zone through at least one orifice having an area of 0.07 to 300 mm 2 while maintaining the interior of the container at a constant temperature and constant pressure.
Claim 3
Dependent Claim
16 words
A process as defined in claim 1 wherein the orifice is formed in an orifice plate.
Claim 4
Dependent Claim
42 words
A process as defined in claim 1 wherein the interior of the container is maintained at constant pressure, and the partial pressure of the volatile blowing agent in the interior vapor-phase portion of the container is also maintained at a constant level.
Claim 5
Dependent Claim
26 words
A process as defined in claim 1 wherein a fine powder of sparingly water-soluble inorganic substance and an anionic surfactant are used conjointly as dispersion stabilizers.
Claim 6
Dependent Claim
40 words
A process as defined in claim 1 wherein the polyolefin resin is selected from the group consisting of low-density polyethylene, straight-chain low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, polypropylene, ethylene-propylene random copolymer, ethylene-propylene block copolymer and ethylene-propylene-butene terpolymer.
Claim 7
Dependent Claim
32 words
A process as defined in claim 5 wherein the polyolefin resin contains 0.01 to 5 parts by weight of an inorganic nucleating agent per 100 parts by weight of the polyolefin resin.
Claim 8
Dependent Claim
31 words
A process as defined in claim 5 wherein the polyolefin resin is ethylene-propylene random copolymer having an ethylene content of 1 to 15% by weight and MI of 0.1 to 40.
References Cited (Backward Citations)
US4247650A
Cited
US4366263A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-05-15 | 1987-11-14 | 1988-05-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-05-15 | 1991-11-14 | 1992-05-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-05-15 | 1995-11-14 | 1996-05-15 | $7700.00 | Window Closed / Lapsed |