WO1997044383A1 - Extrusion foaming of fluoropolymers - Google Patents
Extrusion foaming of fluoropolymers Download PDFInfo
- Publication number
- WO1997044383A1 WO1997044383A1 PCT/US1997/008449 US9708449W WO9744383A1 WO 1997044383 A1 WO1997044383 A1 WO 1997044383A1 US 9708449 W US9708449 W US 9708449W WO 9744383 A1 WO9744383 A1 WO 9744383A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- pressure
- resin
- extrusion
- foaming
- fluoropolymer
- Prior art date
Links
- 229920002313 fluoropolymer Polymers 0.000 title claims abstract description 39
- 239000004811 fluoropolymer Substances 0.000 title claims abstract description 39
- 238000001125 extrusion Methods 0.000 title claims abstract description 32
- 238000005187 foaming Methods 0.000 title claims description 26
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims abstract description 48
- 239000011347 resin Substances 0.000 claims abstract description 47
- 229920005989 resin Polymers 0.000 claims abstract description 47
- 229910002092 carbon dioxide Inorganic materials 0.000 claims abstract description 35
- 239000001569 carbon dioxide Substances 0.000 claims abstract description 13
- 239000004088 foaming agent Substances 0.000 claims abstract description 4
- 238000000034 method Methods 0.000 claims description 22
- 238000002844 melting Methods 0.000 claims description 15
- 230000008018 melting Effects 0.000 claims description 15
- 229920005548 perfluoropolymer Polymers 0.000 claims description 2
- 238000002347 injection Methods 0.000 description 14
- 239000007924 injection Substances 0.000 description 14
- 239000007789 gas Substances 0.000 description 10
- BFKJFAAPBSQJPD-UHFFFAOYSA-N tetrafluoroethene Chemical group FC(F)=C(F)F BFKJFAAPBSQJPD-UHFFFAOYSA-N 0.000 description 9
- 239000002667 nucleating agent Substances 0.000 description 8
- 229920000642 polymer Polymers 0.000 description 8
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 7
- 229920001577 copolymer Polymers 0.000 description 7
- 239000006260 foam Substances 0.000 description 7
- -1 polyethylene Polymers 0.000 description 7
- 210000000497 foam cell Anatomy 0.000 description 6
- 239000004604 Blowing Agent Substances 0.000 description 4
- 125000004432 carbon atom Chemical group C* 0.000 description 4
- 239000000178 monomer Substances 0.000 description 4
- KHXKESCWFMPTFT-UHFFFAOYSA-N 1,1,1,2,2,3,3-heptafluoro-3-(1,2,2-trifluoroethenoxy)propane Chemical compound FC(F)=C(F)OC(F)(F)C(F)(F)C(F)(F)F KHXKESCWFMPTFT-UHFFFAOYSA-N 0.000 description 3
- VOPWNXZWBYDODV-UHFFFAOYSA-N Chlorodifluoromethane Chemical compound FC(F)Cl VOPWNXZWBYDODV-UHFFFAOYSA-N 0.000 description 3
- 239000005977 Ethylene Substances 0.000 description 3
- UUAGAQFQZIEFAH-UHFFFAOYSA-N chlorotrifluoroethylene Chemical group FC(F)=C(F)Cl UUAGAQFQZIEFAH-UHFFFAOYSA-N 0.000 description 3
- KKKYJLNWARAYSD-UHFFFAOYSA-N hexacalcium;tetraborate Chemical compound [Ca+2].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[O-]B([O-])[O-].[O-]B([O-])[O-].[O-]B([O-])[O-].[O-]B([O-])[O-] KKKYJLNWARAYSD-UHFFFAOYSA-N 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 238000010791 quenching Methods 0.000 description 3
- 238000007493 shaping process Methods 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- BQCIDUSAKPWEOX-UHFFFAOYSA-N 1,1-Difluoroethene Chemical group FC(F)=C BQCIDUSAKPWEOX-UHFFFAOYSA-N 0.000 description 2
- PZNSFCLAULLKQX-UHFFFAOYSA-N Boron nitride Chemical compound N#B PZNSFCLAULLKQX-UHFFFAOYSA-N 0.000 description 2
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- 239000004698 Polyethylene Substances 0.000 description 2
- 229920006362 Teflon® Polymers 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 230000006837 decompression Effects 0.000 description 2
- FJKIXWOMBXYWOQ-UHFFFAOYSA-N ethenoxyethane Chemical compound CCOC=C FJKIXWOMBXYWOQ-UHFFFAOYSA-N 0.000 description 2
- HCDGVLDPFQMKDK-UHFFFAOYSA-N hexafluoropropylene Chemical group FC(F)=C(F)C(F)(F)F HCDGVLDPFQMKDK-UHFFFAOYSA-N 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 238000001746 injection moulding Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229920000573 polyethylene Polymers 0.000 description 2
- 239000011800 void material Substances 0.000 description 2
- HUPGRQWHZOWFPQ-UHFFFAOYSA-N 1,1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10-henicosafluorododecane Chemical compound CCC(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)F HUPGRQWHZOWFPQ-UHFFFAOYSA-N 0.000 description 1
- BLTXWCKMNMYXEA-UHFFFAOYSA-N 1,1,2-trifluoro-2-(trifluoromethoxy)ethene Chemical compound FC(F)=C(F)OC(F)(F)F BLTXWCKMNMYXEA-UHFFFAOYSA-N 0.000 description 1
- GVEUEBXMTMZVSD-UHFFFAOYSA-N 3,3,4,4,5,5,6,6,6-nonafluorohex-1-ene Chemical group FC(F)(F)C(F)(F)C(F)(F)C(F)(F)C=C GVEUEBXMTMZVSD-UHFFFAOYSA-N 0.000 description 1
- 229910052582 BN Inorganic materials 0.000 description 1
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 159000000009 barium salts Chemical class 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 210000004027 cell Anatomy 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000002845 discoloration Methods 0.000 description 1
- 229920001038 ethylene copolymer Polymers 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 229920001903 high density polyethylene Polymers 0.000 description 1
- 239000004700 high-density polyethylene Substances 0.000 description 1
- 229920001519 homopolymer Polymers 0.000 description 1
- 229920001684 low density polyethylene Polymers 0.000 description 1
- 239000004702 low-density polyethylene Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000000025 natural resin Substances 0.000 description 1
- JCXJVPUVTGWSNB-UHFFFAOYSA-N nitrogen dioxide Inorganic materials O=[N]=O JCXJVPUVTGWSNB-UHFFFAOYSA-N 0.000 description 1
- 229910052756 noble gas Inorganic materials 0.000 description 1
- 150000002835 noble gases Chemical class 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 229920000620 organic polymer Polymers 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 239000004417 polycarbonate Substances 0.000 description 1
- 229920000515 polycarbonate Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 229920000915 polyvinyl chloride Polymers 0.000 description 1
- 239000004800 polyvinyl chloride Substances 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/04—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent
- C08J9/12—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a physical blowing agent
- C08J9/122—Hydrogen, oxygen, CO2, nitrogen or noble gases
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
- B29C48/07—Flat, e.g. panels
- B29C48/08—Flat, e.g. panels flexible, e.g. films
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/25—Component parts, details or accessories; Auxiliary operations
- B29C48/78—Thermal treatment of the extrusion moulding material or of preformed parts or layers, e.g. by heating or cooling
- B29C48/86—Thermal treatment of the extrusion moulding material or of preformed parts or layers, e.g. by heating or cooling at the nozzle zone
- B29C48/865—Heating
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2327/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
- C08J2327/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
- C08J2327/12—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
Definitions
- This invention is in the field of melt-fabricable fluoropolymers, specifically relating to the foaming of such resins during fabrication.
- U.S. Patent 5,186,986 discloses the foaming of polymer plastic material, naming polyvinyl chloride, polyethylene terphthalate, high and low density polyethylene, and polycarbonate.
- the foaming is carried out by forming a supercritical fluid/polymer solution, either within an extruder or downstream from the extruder. In either case, the polymer is first fabricated into its desired shape, then this desired shape is foamed, i.e., post-fabrication foaming.
- the polymer is extruded in the foam of a sheet into a chamber wherein the sheet is maintained as such by passing through a series of rolls. Downstream from the rolls, the sheet is foamed.
- Patent 5,160,674 discloses injection molding wherein a molded article is first formed under pressure to prevent foaming, followed by reducing the temperature of the article to cause nucleation of foam cells and then reducing pressure of the mold, to permit the article to foam.
- the polymers disclosed are polyethylene and polypropylene, and the gaseous blowing agents that can be used are air, noble gases, nitrogen, or carbon dioxide.
- This patent also discloses extrusion shaping of the fabricated article. wherein the gas is diffused into the polymer in a diffusion chamber situated between the extruder and the shaping die or within the extruder itself.
- resin melt temperatures are about 80°-120°C above the melting point of the perfluorinated polymers and about 40°-75°C above the melting point of the fluoropolymers that are ethylene copolymers. These are normal melt temperatures for extrusion of these resins. See, for example, "Extrusion Guide for Melt- Processible Fluoropolymers” (DuPont, 1993).
- Extrusion foaming of fluoropolymer resin i.e., simultaneous extrusion and foaming
- has had the disadvantage of fluoropolymer requiring high extrusion temperatures because of the high melting temperatures of such resins, with the extrusion temperature being at least 40°C and as much as 120°C higher than the melting temperature, so that the resin will have sufficient fluidity to be foamable.
- the resin is subject to some degradation which can manifest itself as discoloration or falling off of physical, chemical, or electrical properties. This is a particular problem with copolymers of ethylene and chlorotrifluoroethylene. Extusion foaming of fluoropolymer resins which does not have this problem is desired.
- This invention is a process for extrusion foaming of melt-fabricable fluoropolymer resin, in which the foaming (blowing) agent is carbon dioxide and the temperature of the fluoropolymer resin is in a range below the normal melt temperature for extrusion of the resin.
- the temperature of the resin at the extrusion die is from about 60°C above the melting temperature of the fluoropolymer in the absence of carbon dioxide to a temperature below such melting point of the resin.
- the temperature range is from about 35°C above to a temperature below the melting point in the absence of carbon dioxide.
- the carbon dioxide is injected into the extrusion process at a pressure that is at least the critical pressure, so that the carbon dioxide is in a supercritical state.
- extrusion foaming includes not only the common process in which a foamed fluoropolymer shape is formed by extruding under pressure a fluoropolymer resin containing dissolved CO2 through a shaping die into an unrestricted region at atmospheric pressure where the C0 2 expands to foam the resin, but also processes in which the resin/C ⁇ 2 under pressure is extruded into a bounded region at low pressure, usually atmospheric pressure, wherein the pressure on the CO 2 is reduced and the foaming fluoropolymer expands to fill the bounded region.
- One such process is injection molding of foamed articles.
- the extrusion foaming process of this invention can be carried out by techniques known in the art.
- CO 2 foaming agent
- foaming processes are described in the prior art. See, for example, U.S. Patents 4,764,538 and 5,023,279.
- Such techniques commonly employ injection of the foaming agent into the extruder barrel. Either high-pressure or low-pressure CO 2 injection can be employed. If CO 2 is injected at low pressure, the pressure generally increases as resin and CO 2 traverse the extruder to the die, especially at lower temperature. It is preferred that the pressure at the die is at least the critical pressure of CO 2 , which is about 1070 psig (7.48 MPa).
- the CO 2 is in a supercritical state, since the critical temperature for CO 2 is relatively low at about 31 °C and T m for fluoropolymers is relatively high.
- the pressure at the die is a function of several variables including the extruder, the die, the extrusion rate, the fluoropolymer resin, the temperature, and the amount of CO 2 .
- C0 2 is injected at a pressure that is at least the critical pressure so that CO 2 is supercritical from the point of intection to the die.
- the temperature (T) of the resin (containing CO 2 ) at the extrusion die is lower than the temperature at which the fluoropolymer resin is normally extruded, or extrusion foamed.
- This resin temperature is generally in the range of from about 40°C below to about 35°C above the melting temperature (T m ) of the fluoropolymer resin in the absence of carbon dioxide, except that for perfluoropolymer resins T can be as much as 60°C, preferably no more than 40°C or 50°C, above T m .
- T is no more than 20°C below T m .
- T can be no more than 30°C, preferably no more than 20°C, above T m .
- the fluoropolymer resins useful in the present invention include all such resins that can be foamed by a gas injection process. More specifically, the fluoropolymer resins useful in the present invention are organic polymeric compounds containing at least 35 wt% fluorine and are melt fabricable. As such, they generally have a melt flow rate (MFR) of about 1-100 g/l 0 min as measured according to ASTM D-1238 at the temperature appropriate to each resin. Preferred MFR is in the range 5-25 g/10 min.
- fluoropolymers are: (a) homopolymers ofchlorotrifluoroethylene (CTFE),
- E ethylene
- PAVE perfluoro(alkyl vinyl ethers)
- PAVE perfluoro(alkoxy alkyl vinyl ether) having 5-12 carbon atoms
- perfluoroalkyl ethylene having 3-8 carbon atoms.
- Especially preferred fluoropolymers are the perfluorinated copolymers TFE/hexafluoropropylene, optionally including one or more additional monomers; and TFE and at least one perfluoro(alkyl vinyl ether) selected from perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), and perfluoro(propyl vinyl ether); and the hydrogen-containing copolymers E/TFE including E/TFE/perfluorobutyl ethylene; E/CTFE; and polyvinylidene fluoride.
- the fluoropolymer resin used in the extrusion foaming process of this invention contains a foam cell nucleating agent.
- foam cell nucleating agents are disclosed, for example, in U.S. Patents 3,072,583; 4,764,538; and 5,023,279.
- foaming results vary with equipment, extrusion conditions, and foaming method as well as with resin, nucleating agent, and nucleating agent concentration. Thus, results obtained in one test or set of tests may not be directly comparable with the results of another test or set of tests.
- the foaming process was a continuous injection foaming process carried out using an Entwistle 1.25 -inch (31.8-mm) extruder having length/diameter ratio of 30/1 and using carbon dioxide as the blowing agent unless otherwise noted.
- Void fraction was calculated from the measured density of foamed extrudate. using 2.15 as the specific gravity of the fluoropolymer resin. Average foam cell size was determined at mid-wall of the foamed extrudate by taking a photograph of a thin section of the foam at 40-150 ⁇ magnification and measuring cell size on the photograph.
- Example 1 was a tubing extrusion with no automatic windup, the extrudate simply dropping into a water quench about 2 ft (0.6 m) below the die.
- Examples 2-4 were carried out using a die having 90 individual orifices, each 0.031 inch (0.79 mm) in diameter, distributed in a 4 inch by 0.2 inch (102 mm by 5 mm) array. With this die, the individual headings foamed upon exiting the orifices and merged to form a rough slab having no gross space between the headings. This slab was led away from the die with a puller, narrowing to a width of about 3 inch (76 mm), and was cooled in air.
- the fluoropolymer resin (PFA) used in Examples 1-2 was a copolymer of tetrafluoroethylene (TFE) and perfluoro(propyl vinyl ether) (PPVE) having a nominal melting temperature of 302°-310°C by DSC (Teflon® PFA fluoropolymer resin grade 340, DuPont).
- a foam nucleating agent system was introduced as a concentrate of boron nitride (BN), calcium tetraborate (CaTB), and the barium salt of a mixture of perfluoroalkyl ethane sulfonic acids (BaS- 10, CAS No. IC3-56-0) in the same type of resin.
- the concentrations of nucleating agent constituents in the extrudate. i.e., after combining with the natural resin, are given in Table 1.
- the fluoropolymer resin (FEP) used in Examples 3-4 was a copolymer of tetrafluoroethylene and hexafluoropropy lene, ASTM D-2116 Type I (Teflon® FEP fluoropolymer resin grade 100, DuPont). Typical melting point for this resin is 264°C.
- the nucleating agent constituents and their concentrations are also given in Table 1.
- Example 5-9 the procedures of Example 1 were essentially followed, except that the die diameter was 4.57 mm, an extruder screw designed for high pressure gas injection (no decompression zone) was used, two orifices designated A and B normally used for high-pressure (see U.S. Patent 3,975,473) gas injection were used to test different gas flow rates, the length of the air gap to the water quench was approximately 0.3 m, CO 2 from a cylinder source was compressed to higher pressure using a gas booster (Model AGT-32/62, Haskel International) so that injection pressures were above the critical pressure, and the operating conditions were as listed in Table 2.
- a gas booster Model AGT-32/62, Haskel International
- Comparison B differed from the foregoing in that high pressure cylinder nitrogen was used instead of C0 2 -
- Example 10 the procedures of Example 2 (slab die) were essentially followed except for the screw and C0 2 delivery changes noted above and the operating conditions as listed in Table 2. Properties of the foamed extrudates, also listed in Table 2. show that good foams can be obtained at low melt temperatures.
- Example 9 and Comparison B. run under the same conditions except for the blowing agent, CO 2 gave increased foaming as indicated by the dimensions and higher void fraction, even though nitrogen is also supercritical under the conditions employed.
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- Mechanical Engineering (AREA)
- Health & Medical Sciences (AREA)
- Thermal Sciences (AREA)
- Materials Engineering (AREA)
- Physics & Mathematics (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
- Extrusion Moulding Of Plastics Or The Like (AREA)
Abstract
Fluoropolymer resin is extrusion foamed at low temperature using carbon dioxide as the foaming agent.
Description
TITLE
EXTRUSION FOAMING OF FLUOROPOLYMERS
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the benefit of U.S. Provisional Application No. 60/018.092 filed May 22, 1996.
FIELD OF THE INVENTION
This invention is in the field of melt-fabricable fluoropolymers, specifically relating to the foaming of such resins during fabrication.
BACKGROUND OF THE INVENTION U.S. Patent 5,186,986 discloses the foaming of polymer plastic material, naming polyvinyl chloride, polyethylene terphthalate, high and low density polyethylene, and polycarbonate. The foaming is carried out by forming a supercritical fluid/polymer solution, either within an extruder or downstream from the extruder. In either case, the polymer is first fabricated into its desired shape, then this desired shape is foamed, i.e., post-fabrication foaming. Thus, the polymer is extruded in the foam of a sheet into a chamber wherein the sheet is maintained as such by passing through a series of rolls. Downstream from the rolls, the sheet is foamed. U.S. Patent 5,160,674 discloses injection molding wherein a molded article is first formed under pressure to prevent foaming, followed by reducing the temperature of the article to cause nucleation of foam cells and then reducing pressure of the mold, to permit the article to foam. In this patent the polymers disclosed are are polyethylene and polypropylene, and the gaseous blowing agents that can be used are air, noble gases, nitrogen, or carbon dioxide. This patent also discloses extrusion shaping of the fabricated article. wherein the gas is diffused into the polymer in a diffusion chamber situated between the extruder and the shaping die or within the extruder itself.
Foaming of melt-fabricable fluoropolymer resins, usually by an extrusion process, has also been carried out as illustrated by U.S. Patents 3,072.583; 4,394,460; 4,764,538; 5,023,279; and 5,610,203. For additional examples, see also U.S. Patents 4,711,811 and 4,716,073. The '538 and '279 patents mention carbon dioxide among several gases that can be used in a continuous gas injection process. Both patents state that chlorodifluoromethane (HCFC-22) is especially suited for foaming fluoropolymer resins, and HCFC-22 and nitrogen are the only injected gas blowing agents exemplified. In the examples, resin melt temperatures are about 80°-120°C above the melting point of the perfluorinated polymers and about 40°-75°C above the melting point of the fluoropolymers that are ethylene copolymers. These are normal melt temperatures
for extrusion of these resins. See, for example, "Extrusion Guide for Melt- Processible Fluoropolymers" (DuPont, 1993).
Extrusion foaming of fluoropolymer resin, i.e., simultaneous extrusion and foaming, has had the disadvantage of fluoropolymer requiring high extrusion temperatures, because of the high melting temperatures of such resins, with the extrusion temperature being at least 40°C and as much as 120°C higher than the melting temperature, so that the resin will have sufficient fluidity to be foamable. At such high extrusion temperatures, the resin is subject to some degradation which can manifest itself as discoloration or falling off of physical, chemical, or electrical properties. This is a particular problem with copolymers of ethylene and chlorotrifluoroethylene. Extusion foaming of fluoropolymer resins which does not have this problem is desired.
SUMMARY OF THE INVENTION
This invention is a process for extrusion foaming of melt-fabricable fluoropolymer resin, in which the foaming (blowing) agent is carbon dioxide and the temperature of the fluoropolymer resin is in a range below the normal melt temperature for extrusion of the resin. For perfluorinated polymer, the temperature of the resin at the extrusion die is from about 60°C above the melting temperature of the fluoropolymer in the absence of carbon dioxide to a temperature below such melting point of the resin. For hydrogen-containing fluoropolymer, the temperature range is from about 35°C above to a temperature below the melting point in the absence of carbon dioxide. Preferably, the carbon dioxide is injected into the extrusion process at a pressure that is at least the critical pressure, so that the carbon dioxide is in a supercritical state. DETAILED DESCRIPTION OF THE INVENTION
As used herein, "extrusion foaming" includes not only the common process in which a foamed fluoropolymer shape is formed by extruding under pressure a fluoropolymer resin containing dissolved CO2 through a shaping die into an unrestricted region at atmospheric pressure where the C02 expands to foam the resin, but also processes in which the resin/Cθ2 under pressure is extruded into a bounded region at low pressure, usually atmospheric pressure, wherein the pressure on the CO2 is reduced and the foaming fluoropolymer expands to fill the bounded region. One such process is injection molding of foamed articles. The extrusion foaming process of this invention can be carried out by techniques known in the art. except for the use of CO2 as foaming agent and for the relatively low extrusion temperature. Such foaming processes are described in the prior art. See, for example, U.S. Patents 4,764,538 and 5,023,279. Such
techniques commonly employ injection of the foaming agent into the extruder barrel. Either high-pressure or low-pressure CO2 injection can be employed. If CO2 is injected at low pressure, the pressure generally increases as resin and CO2 traverse the extruder to the die, especially at lower temperature. It is preferred that the pressure at the die is at least the critical pressure of CO2, which is about 1070 psig (7.48 MPa). Under this condition the CO2 is in a supercritical state, since the critical temperature for CO2 is relatively low at about 31 °C and Tm for fluoropolymers is relatively high. As one skilled in the art will recognize, the pressure at the die is a function of several variables including the extruder, the die, the extrusion rate, the fluoropolymer resin, the temperature, and the amount of CO2. Preferably, C02 is injected at a pressure that is at least the critical pressure so that CO2 is supercritical from the point of intection to the die.
In the process of this invention, the temperature (T) of the resin (containing CO2) at the extrusion die is lower than the temperature at which the fluoropolymer resin is normally extruded, or extrusion foamed. This resin temperature is generally in the range of from about 40°C below to about 35°C above the melting temperature (Tm) of the fluoropolymer resin in the absence of carbon dioxide, except that for perfluoropolymer resins T can be as much as 60°C, preferably no more than 40°C or 50°C, above Tm. Preferably, T is no more than 20°C below Tm. For all fluoropolymers, T can be no more than 30°C, preferably no more than 20°C, above Tm.
The fluoropolymer resins useful in the present invention include all such resins that can be foamed by a gas injection process. More specifically, the fluoropolymer resins useful in the present invention are organic polymeric compounds containing at least 35 wt% fluorine and are melt fabricable. As such, they generally have a melt flow rate (MFR) of about 1-100 g/l 0 min as measured according to ASTM D-1238 at the temperature appropriate to each resin. Preferred MFR is in the range 5-25 g/10 min.
Preferred examples of such fluoropolymers are: (a) homopolymers ofchlorotrifluoroethylene (CTFE),
2,2-difluoroethylene, or vinylidene fluoride, or
(b) copolymers of tetrafluoroethylene (TFE) and one of the monomers in (a), or
(c) copolymers of at least one of the monomers in (a) or (b) and one or more monomers selected from the group consisting of ethylene (E), terminally unsaturated perfluoroolefins having 3-8 carbon atoms, perfluoro(alkyl vinyl ethers) (PAVE) having 3-8 carbon atoms, perfluoro(alkoxy alkyl vinyl ether) having 5-12 carbon atoms, and perfluoroalkyl ethylene having 3-8 carbon atoms.
Especially preferred fluoropolymers are the perfluorinated copolymers TFE/hexafluoropropylene, optionally including one or more additional monomers; and TFE and at least one perfluoro(alkyl vinyl ether) selected from perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether), and perfluoro(propyl vinyl ether); and the hydrogen-containing copolymers E/TFE including E/TFE/perfluorobutyl ethylene; E/CTFE; and polyvinylidene fluoride.
Preferably, the fluoropolymer resin used in the extrusion foaming process of this invention contains a foam cell nucleating agent. Such nucleating agents are disclosed, for example, in U.S. Patents 3,072,583; 4,764,538; and 5,023,279.
As well known to those skilled in the art, foaming results vary with equipment, extrusion conditions, and foaming method as well as with resin, nucleating agent, and nucleating agent concentration. Thus, results obtained in one test or set of tests may not be directly comparable with the results of another test or set of tests.
EXAMPLES
In these examples the foaming process was a continuous injection foaming process carried out using an Entwistle 1.25 -inch (31.8-mm) extruder having length/diameter ratio of 30/1 and using carbon dioxide as the blowing agent unless otherwise noted.
Void fraction was calculated from the measured density of foamed extrudate. using 2.15 as the specific gravity of the fluoropolymer resin. Average foam cell size was determined at mid-wall of the foamed extrudate by taking a photograph of a thin section of the foam at 40-150χ magnification and measuring cell size on the photograph.
Examples 1-4
In these examples the extruder was equipped with a decompression screw having a low-pressure zone. Carbon dioxide was injected into this zone at low pressure, with pressure generally increasing as resin and CO2 were pumped along the extruder barrel to the die. Industrial grade cylinder (800 psig, 5.6 MPa) CO2 was used, with pressure controlled by the regulator on the cylinder. Extruder screw design allowed for the gas injection and had a mixing torpedo (U.S. Patent 3,006,029) to provide a uniform melt. Details of the extrusion conditions are given in Table 1. Example 1 was a tubing extrusion with no automatic windup, the extrudate simply dropping into a water quench about 2 ft (0.6 m) below the die. Examples 2-4 were carried out using a die having 90 individual orifices, each 0.031 inch (0.79 mm) in diameter, distributed in a 4 inch by 0.2 inch (102 mm by
5 mm) array. With this die, the individual headings foamed upon exiting the orifices and merged to form a rough slab having no gross space between the headings. This slab was led away from the die with a puller, narrowing to a width of about 3 inch (76 mm), and was cooled in air. The fluoropolymer resin (PFA) used in Examples 1-2 was a copolymer of tetrafluoroethylene (TFE) and perfluoro(propyl vinyl ether) (PPVE) having a nominal melting temperature of 302°-310°C by DSC (Teflon® PFA fluoropolymer resin grade 340, DuPont). A foam nucleating agent system was introduced as a concentrate of boron nitride (BN), calcium tetraborate (CaTB), and the barium salt of a mixture of perfluoroalkyl ethane sulfonic acids (BaS- 10, CAS No. IC3-56-0) in the same type of resin. The concentrations of nucleating agent constituents in the extrudate. i.e., after combining with the natural resin, are given in Table 1.
The fluoropolymer resin (FEP) used in Examples 3-4 was a copolymer of tetrafluoroethylene and hexafluoropropy lene, ASTM D-2116 Type I (Teflon® FEP fluoropolymer resin grade 100, DuPont). Typical melting point for this resin is 264°C. The nucleating agent constituents and their concentrations are also given in Table 1.
These PFA and FEP resins are conventionally extruded at melt temperatures in the range 370°-400°C. Nevertheless, the Examples show that good foams can be obtained at lower melt temperatures.
Table 1. Extrusion Detail for Examples 1-4
Example: 1 2 3 4
Resin & nucleating agent
Resin type PFA PFA FEP FEP
BN (wt%) 0.25 0.25 0.25 0.25
CaTB (ppm) 110 110 120 120
BaS- 10 (ppm) 180 180 — —
Extruder
Die type tubing slab slab slab
Die diameter (mm) 3.26 — — —
Guide tip diameter (mm) 1.91 — — —
Temperatures f°C)
Rear 343 343 334 307
Center rear 343 363 348 324
Center 344 363 347 329
Center front 344 363 347 323
Front 318 352 332 308
Clamp 316 329 305 283
Adapter 307 316 295 272
Crosshead 277 316 309 279
Die 278 — — —
Melt (In extrusion die) 287 323 304 278
Running conditions
Screw speed (φm) 21 80 80 80
CO2 injection pressure (MPa) 2.86 2.17 2.17 2.17
Crosshead pressure (MPa) 7.69 3.21 5.90 8.93
Air gap to water quench (m) -0.6 — — —
Extrudate properties
Outside diameter (mm) 3.68 — — —
Wall thickness (mm) 0.06 — — —
Ave. foam cell size (μm) -25 40-60 75-100 —
Voids (%) 39 48 — —
Examples 5-10 and Comparisons A-B
For Examples 5-9 and for Comparison A, the procedures of Example 1 were essentially followed, except that the die diameter was 4.57 mm, an extruder screw designed for high pressure gas injection (no decompression zone) was used, two orifices designated A and B normally used for high-pressure (see U.S. Patent 3,975,473) gas injection were used to test different gas flow rates, the length of the air gap to the water quench was approximately 0.3 m, CO2 from a cylinder source was compressed to higher pressure using a gas booster (Model AGT-32/62, Haskel International) so that injection pressures were above the critical pressure, and the operating conditions were as listed in Table 2.
Comparison B differed from the foregoing in that high pressure cylinder nitrogen was used instead of C02- For Example 10, the procedures of Example 2 (slab die) were essentially followed except for the screw and C02 delivery changes noted above and the operating conditions as listed in Table 2. Properties of the foamed extrudates, also listed in Table 2. show that good foams can be obtained at low melt temperatures. As shown by Example 9 and Comparison B. run under the same conditions except for the blowing agent, CO2 gave increased foaming as indicated by the dimensions and higher void fraction, even though nitrogen is also supercritical under the conditions employed.
Table 2. Extrusion Detail for Examples 5-10 and Comparisons A-B
Example: A 5 6 7
Extruder
Die type tubing tubing tubing tubing
Orifice A A A A
Temperatures (°C)
Rear 358 336 335 335
Center rear 372 343 343 343
Center 372 343 343 343
Center front 372 343 343 343
Front 372 343 343 343
Clamp 372 343 343 302
Adapter 372 343 329 302
Crosshead 344 316 302 288
Die 344 316 302 302
Melt (In extrusion die) 386 357 347 337
Running conditions
Screw speed (φm) 55 55 55 55
CO2 injection pressure (MPa) 17.9 17.9 17.9 23.5
N2 injection pressure (MPa) — — — —
Barrel pressure (MPa) 11.0 10.3 12.7 18.6
Crosshead pressure (MPa) 13.4 12.8 16.6 22.8
Extrudate properties
Outside diameter (mm) 5.33 5.33 5.33 6.10
Wall thickness (mm) 1.71 1.77 1.82 2.09
Ave. foam cell size (μm) 150 220 275 275
Voids (%) 64 55 49 49
Table 2. Continued
Example: 8 9 B 10
Extruder
Die type tubing tubing tubing slab
Orifice B B B B
Temperatures (°C)
Rear 343 343 343 343
Center rear 343 363 343 344
Center 343 343 343 344
Center front 329 329 329 344
Front 316 316 316 329
Clamp 302 302 302 303
Adapter 302 302 302 301
Crosshead 302 302 302 285
Die 302 316 316 —
Melt (In extrusion die) 334 333 333 303
Running conditions
Screw speed (φm) 95 71 71 70
CO2 injection pressure (MPa) 20.7 20.7 — 27.6
N2 injection pressure (MPa) — — 20.7 —
Barrel pressure (MPa) 12.6 13.1 13.1 9.9
Crosshead pressure (MPa) 13.5 12.6 12.8 7.9
Extrudate properties
Outside diameter (mm) 4.83 6.86 5.08 —
Wall thickness (mm) 1.40 1.59 1.38 —
Ave. foam cell size (μm) 35 80 40 200
Voids (%) 44 73 63 41
Claims
1. In the process of extrusion foaming of melt-fabricable fluoropolymer resin, the improvement comprising carrying out said foaming wherein carbon dioxide is used as the foaming agent and the temperature of said fluoropolymer resin is from about 60°C above the melting temperature of said fluoropolymer resin in the absence of carbon dioxide to a temperature below such melting point of said resin, provided that when said fluoropolymer is hydrogen- containing fluoropolymer said temperature is no more than about 35°C above said melting point.
2. The process of Claim 1, wherein said fluoropolymer is perfluoropolymer and said temperature is no more than 50°C above said melting point.
3. The process of Claim 1, wherein said temperature is no more than 30°C above said melting point.
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP97925634A EP0900251B1 (en) | 1996-05-22 | 1997-05-19 | Extrusion foaming of fluoropolymers |
JP54261997A JP3929497B2 (en) | 1996-05-22 | 1997-05-19 | Fluoropolymer extrusion foaming |
DE69700812T DE69700812T2 (en) | 1996-05-22 | 1997-05-19 | EXTRUSION FOAMING OF FLUORINE POLYMERS |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US1809296P | 1996-05-22 | 1996-05-22 | |
US60/018,092 | 1996-05-22 | ||
US08/854,201 US5821273A (en) | 1996-05-22 | 1997-05-09 | Extrusion foaming of fluoropolymers |
US08/854,201 | 1997-05-09 |
Publications (1)
Publication Number | Publication Date |
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WO1997044383A1 true WO1997044383A1 (en) | 1997-11-27 |
Family
ID=26690725
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PCT/US1997/008449 WO1997044383A1 (en) | 1996-05-22 | 1997-05-19 | Extrusion foaming of fluoropolymers |
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US (1) | US5821273A (en) |
EP (1) | EP0900251B1 (en) |
JP (1) | JP3929497B2 (en) |
DE (1) | DE69700812T2 (en) |
WO (1) | WO1997044383A1 (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1935931A1 (en) * | 2006-12-20 | 2008-06-25 | Nexans | High processing temperature foaming polymer composition |
CN109735030A (en) * | 2018-12-13 | 2019-05-10 | 济南赛辰高分子材料有限公司 | A kind of fluorine Material Physics foaming nucleation masterbatch |
US10304585B2 (en) | 2013-01-24 | 2019-05-28 | Daikin Industries, Ltd. | Composition, and method for producing foam molded material and electric wire |
US10557006B2 (en) | 2013-01-24 | 2020-02-11 | Daikin Industries, Ltd. | Composition, and method for producing foam molded material and electric wire |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6403663B1 (en) | 1999-09-20 | 2002-06-11 | North Carolina State University | Method of making foamed materials using surfactants and carbon dioxide |
GB0030182D0 (en) * | 2000-12-11 | 2001-01-24 | Univ Brunel | Material processing |
WO2003035750A1 (en) * | 2001-10-25 | 2003-05-01 | Virginia Commonwealth University | Fluoropolymer-carbon dioxide compositions and methods of processing fluoropolymers |
US20030176516A1 (en) * | 2002-03-15 | 2003-09-18 | Greene, Tweed Of Delaware, Inc. | Cellular perfluoroelastomeric compositions, sealing members, methods of making the same and cellular materials for medical applications |
US20080149899A1 (en) * | 2006-12-21 | 2008-06-26 | E. I. Du Pont De Nemours And Company | Foamable Fluoropolymer Composition |
CN103897309B (en) * | 2014-04-09 | 2016-05-18 | 中国科学院宁波材料技术与工程研究所 | A kind of preparation method of high temperature resistant type fluoropolymer poromerics |
CN109081936A (en) * | 2017-06-14 | 2018-12-25 | 宁波绿色方舟环境科技有限公司 | A kind of fluoropolymer cellular material and preparation method thereof |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH01149839A (en) * | 1987-12-04 | 1989-06-12 | Hitachi Cable Ltd | Production of foamed resin article |
US5023279A (en) * | 1989-02-17 | 1991-06-11 | E. I. Du Pont De Nemours And Company | Nucleating agents for thermoplastic resins |
JPH0547221A (en) * | 1991-08-12 | 1993-02-26 | Hitachi Cable Ltd | Foamed fluorine resin insulated wire |
JPH06139850A (en) * | 1991-06-25 | 1994-05-20 | Hitachi Cable Ltd | Manufacture of foamed platic insulated electric wire |
WO1995011935A1 (en) * | 1993-10-29 | 1995-05-04 | E.I. Du Pont De Nemours And Company | Solutions of perfluorinated polymers in supercritical co¿2? |
Family Cites Families (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3006029A (en) * | 1958-11-13 | 1961-10-31 | Du Pont | Extruder mixing screw |
NL258835A (en) * | 1959-12-18 | |||
US3975473A (en) * | 1974-09-12 | 1976-08-17 | Union Carbide Corporation | Process for production of cellular thermoplastic bodies |
US4394460A (en) * | 1980-12-08 | 1983-07-19 | Allied Corporation | Ethylene-chlorotrifluoroethylene copolymer foam |
US4716073A (en) * | 1986-06-02 | 1987-12-29 | E. I. Du Pont De Nemours And Company | Thin wall high performance insulation on wire |
US4711811A (en) * | 1986-10-22 | 1987-12-08 | E. I. Du Pont De Nemours And Company | Thin wall cover on foamed insulation on wire |
US5160674A (en) * | 1987-07-29 | 1992-11-03 | Massachusetts Institute Of Technology | Microcellular foams of semi-crystaline polymeric materials |
US4764538A (en) * | 1987-12-16 | 1988-08-16 | E. I. Du Pont De Nemours And Company | Foam nucleation system for fluoropolymers |
US5158986A (en) * | 1991-04-05 | 1992-10-27 | Massachusetts Institute Of Technology | Microcellular thermoplastic foamed with supercritical fluid |
US5610203A (en) * | 1996-04-10 | 1997-03-11 | E. I. Du Pont De Nemours And Company | Foamable fluoropolymer composition |
-
1997
- 1997-05-09 US US08/854,201 patent/US5821273A/en not_active Expired - Lifetime
- 1997-05-19 JP JP54261997A patent/JP3929497B2/en not_active Expired - Fee Related
- 1997-05-19 EP EP97925634A patent/EP0900251B1/en not_active Expired - Lifetime
- 1997-05-19 DE DE69700812T patent/DE69700812T2/en not_active Expired - Fee Related
- 1997-05-19 WO PCT/US1997/008449 patent/WO1997044383A1/en active IP Right Grant
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH01149839A (en) * | 1987-12-04 | 1989-06-12 | Hitachi Cable Ltd | Production of foamed resin article |
US5023279A (en) * | 1989-02-17 | 1991-06-11 | E. I. Du Pont De Nemours And Company | Nucleating agents for thermoplastic resins |
JPH06139850A (en) * | 1991-06-25 | 1994-05-20 | Hitachi Cable Ltd | Manufacture of foamed platic insulated electric wire |
JPH0547221A (en) * | 1991-08-12 | 1993-02-26 | Hitachi Cable Ltd | Foamed fluorine resin insulated wire |
WO1995011935A1 (en) * | 1993-10-29 | 1995-05-04 | E.I. Du Pont De Nemours And Company | Solutions of perfluorinated polymers in supercritical co¿2? |
Non-Patent Citations (3)
Title |
---|
DATABASE WPI Section Ch Week 8931, Derwent World Patents Index; Class A18, AN 89-223021, XP002039888 * |
DATABASE WPI Section Ch Week 9313, Derwent World Patents Index; Class A14, AN 93-105413, XP002039887 * |
DATABASE WPI Section Ch Week 9425, Derwent World Patents Index; Class A18, AN 94-203334, XP002039886 * |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1935931A1 (en) * | 2006-12-20 | 2008-06-25 | Nexans | High processing temperature foaming polymer composition |
US10304585B2 (en) | 2013-01-24 | 2019-05-28 | Daikin Industries, Ltd. | Composition, and method for producing foam molded material and electric wire |
US10557006B2 (en) | 2013-01-24 | 2020-02-11 | Daikin Industries, Ltd. | Composition, and method for producing foam molded material and electric wire |
CN109735030A (en) * | 2018-12-13 | 2019-05-10 | 济南赛辰高分子材料有限公司 | A kind of fluorine Material Physics foaming nucleation masterbatch |
Also Published As
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US5821273A (en) | 1998-10-13 |
JP2000511124A (en) | 2000-08-29 |
EP0900251A1 (en) | 1999-03-10 |
JP3929497B2 (en) | 2007-06-13 |
DE69700812D1 (en) | 1999-12-23 |
EP0900251B1 (en) | 1999-11-17 |
DE69700812T2 (en) | 2000-06-29 |
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