US5830393A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for preparing expanded product of thermoplastic resin
Assignee: Mitsui Chemicals Inc
•
Filing: 1997-07-02
•
Granted: 1998-11-03
•
Expires: 2017-07-02
Abstract
Abstract A process for preparing an expanded product of a thermoplastic resin which includes a gas dissolving step of adding supercritical carbon dioxide and/or nitrogen as an blowing agent to a thermoplastic resin, and melting it in the thermoplastic resin, a cooling step of cooling the resulting molten resin composition under a pressure not less than a critical pressure of the blowing agent, a nuclei forming step of discharging the molten resin composition from a die to lower the pressure to a level not more than the critical pressure, and an expansion controlling step of cooling an expanded product of the thermoplastic resin to a level not more than a glass transition temperature or a crystallization temperature of the resin to control a cell diameter of the expanded product.
Inventors
- 👤 Shigeo Nishikawa
- 👤 Kaoru Yorita
- 👤 Kouzo Ichikawa
- 👤 Haruo Inoue
- 👤 Michio Eriguchi
- 👤 Takanori Sueda
- 👤 Hideo Amemiya
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 00:02
CPC Classifications
C; C08; C08J; C08J9/00; B; B29; B29C; B29C44/00; B29C44/34; B29C44/36; B29C44/46; B29C44/461; B29C44/3442; B29C44/3446; B29C44/3469; B29C44/348; Y; Y10; Y10S; Y10S264/00; Y10S264/13
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
374 words
A process for preparing an expanded product of a thermoplastic resin by extrusion molding which comprises: (I) a gas dissolving step of the thermoplastic resin at 100° to 450° C. in a continuous plasticator having a line for feeding an blowing agent, and adding supercritical carbon dioxide and/or nitrogen in a ratio of 0.1 to 30 parts by weight with respect to 100 parts by weight of the thermoplastic resin to form a molten resin composition in which the thermoplastic resin is compatible with supercritical carbon dioxide and/or nitrogen, (II) a cooling step of cooling, the molten resin composition to a temperature of 50° to 300° C. at a tip portion of the continuous plasticator, while maintaining a pressure not less than a critical pressure of supercritical carbon dioxide and/or nitrogen, (III) a nuclei cell forming step of discharging the molten resin composition from a die connected to the tip portion of the continuous plasticator and set to an optimum expansion temperature of the molten resin composition, whereby the pressure is lowered to a level not more than the critical pressure of supercritical carbon dioxide and/or nitrogen to form cell nuclei, and (IV) an expansion controlling step of rapidly cooling the extruded product of the thermoplastic resin to a level not more than a glass transition temperature or a crystallization temperature of the resin to control a cell diameter of the expanded product, wherein the die in the step (III) has a flow velocity distribution adjusting section having a function of lowering the shear rate on the downstream side of a shear rate adjusting section having a function of generating the shear rate of the molten resin composition (hereinafter referred to simply "the shear rate") in the range of 10 2 to 10 4 sec -1 ; this shear rate adjusting section includes a portion (an average sectional area A) in which a sectional area of a section vertical to a resin flow direction on the upstream side of a resin flow path is narrowed; the flow velocity distribution adjusting section includes a portion (an average sectional area B) in which the same section is spread on the downstream side of the flow path; and B/A is in the range of 1.3 to 20.
Claim 2
Dependent Claim
374 words
A process for preparing an expanded product of a thermoplastic resin by extrusion molding which comprises: (I) a gas dissolving step of the thermoplastic resin at 100° to 450° C. in a continuous plasticator having a line for feeding an blowing agent, and adding supercritical carbon dioxide and/or nitrogen in a ratio of 0.1 to 30 parts by weight with respect to 100 parts by weight of the thermoplastic resin to form a molten resin composition in which the thermoplastic resin is compatible with supercritical carbon dioxide and/or nitrogen, (II) a cooling step of cooling, the molten resin composition to a temperature of 50° to 300° C. at a tip portion of the continuous plasticator, while maintaining a pressure not less than a critical pressure of supercritical carbon dioxide and/or nitrogen, (III) a nuclei cell forming step of discharging the molten resin composition from a die connected to the tip portion of the continuous plasticator and set to an optimum expansion temperature of the molten resin composition, whereby the pressure is lowered to a level not more than the critical pressure of supercritical carbon dioxide and/or nitrogen to form cell nuclei, and (IV) an expansion controlling step of rapidly cooling the extruded product of the thermoplastic resin to a level not more than a glass transition temperature or a crystallization temperature of the resin to control a cell diameter of the expanded product, wherein the die in the step (III) has a flow velocity distribution adjusting section having a function of lowering the shear rate on the downstream side of a shear rate adjusting section having a function of generating the shear rate of the molten resin composition (hereinafter referred to simply "the shear rate") in the range of 10 2 to 10 4 sec -1 ; this shear rate adjusting section includes a portion (an average sectional area A) in which a sectional area of a section vertical to a resin flow direction on the upstream side of a resin flow path is narrowed; the flow velocity distribution adjusting section includes a portion (an average sectional area B) in which the same section is spread on the downstream side of the flow path; and B/A is in the range of 1.3 to 20.
Claim 3
Dependent Claim
32 words
The process for preparing an expanded product of a thermoplastic resin according to claim 1 wherein the die has a function of changing a sectional area of the shear rate adjusting section.
Claim 4
Dependent Claim
38 words
The process for preparing an expanded product of a thermoplastic resin according to claim 1 wherein a resin pressure at an inlet of the shear rate adjusting section is in the range of 50to 400 kg/cm 2 .
Claim 5
Dependent Claim
53 words
The process for preparing an expanded product of a thermoplastic resin according to claim 1 wherein a ratio C/A between the average sectional area A of the shear rate adjusting section and a sectional area C of the obtained expanded product of the thermoplastic resin is in the range of 2 to 200.
Claim 6
Dependent Claim
24 words
The process for preparing an expanded product of a thermoplastic resin according to claim 1 wherein the continuous plasticator is a tandem type extruder.
Claim 7
Dependent Claim
22 words
The process for preparing an expanded product of a thermoplastic resin according to claim 1 wherein the continuous plasticator is one extruder.
Claim 8
Dependent Claim
47 words
The process for preparing an expanded product of a thermoplastic resin according to claim 1 wherein carbon dioxide and/or nitrogen is dissolved in the thermoplastic resin in a ratio of 2 to 20 parts by weight with respect to 100 parts by weight of the thermoplastic resin.
Claim 9
Dependent Claim
32 words
The process for preparing an expanded product of a thermoplastic resin according to claim 1 wherein molten resin composition further comprises as an inorganic fine powder and/or an aliphatic carboxylic acid derivative.
Claim 10
Dependent Claim
22 words
The process for preparing an expanded product of a thermoplastic resin according to claim 8 wherein the inorganic fine powder is talc.
Claim 11
Dependent Claim
27 words
The process for preparing an expanded product of a thermoplastic resin according to claim 8 wherein the aliphatic carboxylic acid derivative is a derivative of stearic acid.
Claim 12
Dependent Claim
24 words
The process for preparing an expanded product of a thermoplastic resin according to claim 10 wherein the aliphatic carboxylic acid derivative is zinc stearate.
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) | 2001-11-02 | 2002-05-04 | 2002-11-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-11-02 | 2006-05-04 | 2006-11-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-11-02 | 2010-05-04 | 2010-11-03 | $7700.00 | Window Closed / Lapsed |