US4226942A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Foamable resins process
Assignee: Bayer Antwerpen NV
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Filing: 1978-08-15
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Granted: 1980-10-07
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Expires: 1998-08-15
Abstract
Abstract This invention relates to an improved process for the production of a particulate foamable polyvinyl aromatic resin of the type wherein a vinyl aromatic monomer is polymerized in an aqueous suspension system to produce beads of thermoplastic polyvinyl aromatic resin, separating the beads and incorporating a volatile liquid blowing agent in the separated beads at a temperature above the resin softening point under such conditions that foamable resin particles are produced, cooling said beads followed by separating and drying said beads, the improvement comprising: drying said beads under vacuum conditions at normal temperatures, removing residual water from said beads while retaining said blowing agent in said beads. Also included in the invention are foamable particles when produced by the above process and foamed articles made from the foamable particles.
Inventors
- 👤 Nan Wei
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 11:17
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/16; C08J9/20; C08J9/22; C08J2325/00; Y; Y10; Y10S; Y10S521/00; Y10S521/918
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
195 words
In an improved process for the production of foamable polyvinyl aromatic resin beads, the steps comprising: (a) polymerizing a vinyl aromatic monomer in a first aqueous suspension system forming polymeric beads of said monomer, (b) separating the beads from the first aqueous suspension, (c) suspending the separated beads under agitation in a second aqueous suspension system, (d) incorporating a volatile liquid blowing agent into the beads at a temperature above the softening temperature of the beads under superatmospheric pressure in a closed vessel, (e) cooling the second aqueous suspension under superatmospheric pressure until the suspended beads have cooled sufficiently to render the beads non-foaming at atmospheric pressures, (f) recovering the beads from the aqueous suspension, (g) drying the beads forming free flowing foamable polyvinyl aromatic polymeric beads having 1-15% of said volatile liquid blowing agent incorporated in the beads, the improvement comprising: drying said beads under vacuum conditions at normal temperatures of about 15° to 45° C., removing residual water from said beads while retaining said blowing agent in said beads and maintaining the structure of said beads as foamable non-foamed beads recovered from step (f), said vacuum being 380 to 735 mm of Hg.
Claim 2
Dependent Claim
195 words
In an improved process for the production of foamable polyvinyl aromatic resin beads, the steps comprising: (a) polymerizing a vinyl aromatic monomer in a first aqueous suspension system forming polymeric beads of said monomer, (b) separating the beads from the first aqueous suspension, (c) suspending the separated beads under agitation in a second aqueous suspension system, (d) incorporating a volatile liquid blowing agent into the beads at a temperature above the softening temperature of the beads under superatmospheric pressure in a closed vessel, (e) cooling the second aqueous suspension under superatmospheric pressure until the suspended beads have cooled sufficiently to render the beads non-foaming at atmospheric pressures, (f) recovering the beads from the aqueous suspension, (g) drying the beads forming free flowing foamable polyvinyl aromatic polymeric beads having 1-15% of said volatile liquid blowing agent incorporated in the beads, the improvement comprising: drying said beads under vacuum conditions at normal temperatures of about 15° to 45° C., removing residual water from said beads while retaining said blowing agent in said beads and maintaining the structure of said beads as foamable non-foamed beads recovered from step (f), said vacuum being 380 to 735 mm of Hg.
Claim 3
Dependent Claim
41 words
The process of claim 1 wherein the second aqueous suspension system has present about 0.03 to 0.6% by weight of a water-soluble polymeric suspending agent selected from the group consisting of hydroxyethylcellulose, vinylpyrrolidenemethylmethacrylate copolymer, partially hydrolyzed polyvinyl acetate and mixtures thereof.
Claim 4
Dependent Claim
20 words
The process of claim 2 wherein the water soluble polymeric suspending agent is a 70% to 85% hydrolyzed polyvinyl acetate.
Claim 5
Dependent Claim
52 words
The process of claim 1 wherein the second aqueous suspension system has present 0.02 to 2.0% by weight of a non-ionic wetting agent for dispersing the blowing agent selected from the group consisting of C 8 -C 2 O alkylbis-(ethanol) amines, polyethyleneglycol, esters and ethers of polyethylene glycol, octylphenylpolyethoxy-ethanol and mixtures thereof.
Claim 6
Dependent Claim
42 words
The process of claim 1 wherein the second aqueous suspending system has present 0.01 to 0.5% by weight based on the aqueous medium of an inorganic salt of the group consisting of sodium chloride, potassium chloride and calcium chloride or mixtures thereof.
Claim 7
Dependent Claim
40 words
The process of claim 1 wherein the blowing agent is pentane, isopentane, butane, mixed hydrocarbons having 5 to 7 carbon atoms or mixtures thereof being incorporated in the beads in from about 1 to 15% by weight of the beads.
Claim 8
Dependent Claim
22 words
The process of claim 9 wherein the blowing agent is a mixture of pentane and isopentane having at least about 50% pentane.
Claim 9
Dependent Claim
13 words
The process of claim 9 wherein the liquid volatile blowing agent is pentane.
Claim 10
Dependent Claim
38 words
The process of claim 1 wherein the blowing agent is incorporated in the beads in step (d) at temperatures of 5° to 55° C. above the softening temperature of the bead over a period of about 1-10 hours.
Claim 11
Dependent Claim
23 words
The process of claim 1 wherein the superatmospheric pressures of step (d) are from about 4 to 15 kilograms per square centimeter gauge.
Claim 12
Dependent Claim
24 words
The process of claim 1 wherein the polyvinyl aromatic resin in polystyrene, copolymers of styrene-acrylonitrile, alpha-methylstyrene, styrene-alpha methyl styrene, styrene-butadiene, styrene-butadiene-acrylonitrile or mixtures thereof.
Claim 13
Dependent Claim
12 words
The process of claim 1 wherein the polyvinyl aromatic resin is polystyrene.
Claim 14
Dependent Claim
25 words
The process according to claim 1 wherein the weight average molecular weight of the polystyrene, as determined by gel permeation chromatography is 180,000 to 300,000.
Claim 15
Dependent Claim
34 words
The process according to claim 1 wherein part at least of the cooling of the resin beads is carried out as rapidly as possible by the introduction of cold water into the suspension system.
Claim 16
Dependent Claim
19 words
The process of claim 1 wherein a bromophenyl alkenyl ether is incorporated into the beads with the blowing agent.
Claim 17
Dependent Claim
15 words
A process of claim 1 wherein said normal temperature is about 15° to 30° C.
Claim 18
Dependent Claim
17 words
A process of claim 1 wherein said vacuum drying is carried out with agitation of said beads.
Claim 19
Dependent Claim
32 words
A process of claim 1 wherein said beads are recovered in step (f) under conditions such that said recovered beads have a residual water content of about 0.5 to 1.5% by weight.
Claim 20
Dependent Claim
12 words
A process of claim 18 wherein said beads are recovered by centrifuging.
Claim 21
Dependent Claim
40 words
A process of claim 1 wherein said vacuum drying is carried out such that the residual water content of said beads is about 0.01 to 0.15% by weight while substantially retaining the amount of blowing agent incorporated in step (d).
Claim 22
Dependent Claim
41 words
A process of claim 1 wherein said vacuum drying is carried out such that the residual water content of said beads is about 0.01 to 0.15% by weight and said beads contain about 1 to 15% by weight of blowing agent.
Claim 23
Dependent Claim
38 words
A process of claim 1 wherein said separating step (b) includes separating a fraction of said beads having a narrow range of bead sizes from said polymerized beads and suspending said fraction in said second aqueous suspension system.
Claim 24
Dependent Claim
14 words
The foamable polyvinyl aromatic resin particle produced by a process according to claim 1.
Claim 25
Dependent Claim
14 words
The foamed article made from the foamable polyvinyl aromatic resin particles of claim 1.
Claim 26
Dependent Claim
99 words
A process for separating a residual aqueous phase from foamable polyvinyl aromatic resin beads containing a volatile liquid blowing agent such that said blowing agent is retained in said beads, the steps comprising: (a) charging said beads to a vacuum drying means, (b) applying a vacuum to said beads at normal temperatures, (c) separating said residual aqueous phase, while retaining said blowing agent in said beads, maintaining the structure of said beads as foamable, non-foamed beads, said vacuum being 380 to 735 mm. of Hg, said temperatures being 15° to 45° C., and (d) recovering said foamable, non-foamed beads.
Claim 27
Dependent Claim
99 words
A process for separating a residual aqueous phase from foamable polyvinyl aromatic resin beads containing a volatile liquid blowing agent such that said blowing agent is retained in said beads, the steps comprising: (a) charging said beads to a vacuum drying means, (b) applying a vacuum to said beads at normal temperatures, (c) separating said residual aqueous phase, while retaining said blowing agent in said beads, maintaining the structure of said beads as foamable, non-foamed beads, said vacuum being 380 to 735 mm. of Hg, said temperatures being 15° to 45° C., and (d) recovering said foamable, non-foamed beads.
Claim 28
Dependent Claim
38 words
A process of claim 25 wherein said recovered beads in step (d) have a residual water content of about 0.01 to 0.15% by weight with said bead containing about 1 to 15% by weight of said blowing agent.
References Cited (Backward Citations)
US3577360A
Cited
US3835073A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-10-07 | 1984-04-07 | 1984-10-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-10-07 | 1988-04-07 | 1988-10-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-10-07 | 1992-04-07 | 1992-10-07 | $7700.00 | Window Closed / Lapsed |