US4433068A
Expired / Lapsed
US
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Process for producing bonded macroballoon structures and resulting product
Assignee: IMI-TECH Corp ELK GROVE ILL A CORP OF
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Filing: 1983-02-17
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Granted: 1984-02-21
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Expires: 2003-02-17
Abstract
Abstract A method of making light weight flame resistant structures from bonded polyimide macroballoons and products thereof. An aromatic tetracarboxylic acid dianhydride is reacted with an oxoimine to produce an N-substituted imide, which is then esterfied with a suitable alcohol. The resulting liquid is dried and the dry residue is reduced to a uniform powder having particles with diameters generally in the 0.5 to 10 mm. range. The powder is preferably further dried, either before or after final size reduction, in a moderate vacuum at moderate temperature to remove any excess residual alcohol. The powder spontaneously expands to form a closed cell foam when heated to a temperature in the range of about 90° to 150° C. for a suitable period. When the powder is expanded in a closed mold, a well consolidated, uniform, closed cell foam product results. The closed cell foam produced has excellent flexibility and resistance to heat and flame, and does not shrink appreciably when exposed to flame. When expanded in an unrestricted manner, closed cell "macroballoons" having average diameters between about 0.4 and 15 mm. result. The macroballoons are useful in a number of applications, including forming a foam-like structure by bonding them together with a very small amount of a suitable resin.
Inventors
- 👤 John V. Long
- 👤 John Gagliani
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 15:19
CPC Classifications
C; C08; C08J; C08J9/00; C08J9/32; B; B32; B32B; B32B5/00; B32B5/18; C08G; C08G73/00; C08G73/06; C08G73/10; C08G73/1003; C08G73/1007; C08G73/1028; C08J9/02; C08J9/16; C08J9/22; C08J9/228; C08J9/236; C08J2379/00; C08J2379/04; C08J2379/08; Y; Y10; Y10S; Y10S264/00; Y10S264/06; Y10S521/00; Y10S521/915
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
171 words
A process for producing high temperature and flame resistant macroballoon structures which comprises the steps of: reacting an oxoimine having the general formula: CH.sub.2 --(CH.sub.2)--NHCO where "X" is a positive integer from 2 to 4 with an aromatic tetracarboxylic acid dianhydride in a mole ratio thereof between about 0.05:1 and 1.5:1 to produce an N-substituted imide; esterfying said N-substituted imide by mixing therewith a reactive solvent; adding thereto at least one diamine; drying the resulting liquid composition; reducing the dried material to an average particle diameter of from about 0.5 to 10 mm.; separating said particles from each other; heating said particles to a temperature in the range of about 90° to 150° C. while substantially preventing interparticle contact, whereby said particles expand producing a plurality of discrete macroballoons; coating said macroballoons with a thin layer of a liquid bonding agent; bringing said macroballoons into contact with each other in a desired structural configuration; and curing said bonding agent to a dry state; whereby a lightweight structure of bonded macroballoons results.
Claim 2
Dependent Claim
171 words
A process for producing high temperature and flame resistant macroballoon structures which comprises the steps of: reacting an oxoimine having the general formula: CH.sub.2 --(CH.sub.2)--NHCO where "X" is a positive integer from 2 to 4 with an aromatic tetracarboxylic acid dianhydride in a mole ratio thereof between about 0.05:1 and 1.5:1 to produce an N-substituted imide; esterfying said N-substituted imide by mixing therewith a reactive solvent; adding thereto at least one diamine; drying the resulting liquid composition; reducing the dried material to an average particle diameter of from about 0.5 to 10 mm.; separating said particles from each other; heating said particles to a temperature in the range of about 90° to 150° C. while substantially preventing interparticle contact, whereby said particles expand producing a plurality of discrete macroballoons; coating said macroballoons with a thin layer of a liquid bonding agent; bringing said macroballoons into contact with each other in a desired structural configuration; and curing said bonding agent to a dry state; whereby a lightweight structure of bonded macroballoons results.
Claim 3
Dependent Claim
39 words
The process according to claim 1 wherein said liquid bonding agent is a synthetic resin selected from the group consisting of epoxies, polyesters, polyimides, polyvinyls, synthetic rubber, fluorinated hydrocarbons, chlorinated hydrocarbons, phenolics, ureas, melamines and mixtures and copolymers thereof.
Claim 4
Dependent Claim
22 words
The process according to claim 1 wherein the bonding agent constitutes up to about 10 wt.% of the dry light weight structure.
Claim 5
Dependent Claim
34 words
The process according to claim 1 wherein said structural configuration is obtained by filling a mold with said coated macroballoons and removing the lightweight structure from the mold after curing of the bonding agent.
Claim 6
Dependent Claim
37 words
The process according to claim 1 wherein said desired structural configuration is obtained by curing said coated microballoons in contact with a surface so that said bonding agent also serves to bond said macroballoons to said surface.
Claim 7
Dependent Claim
25 words
The process according to claim 1 wherein said particles are heated and expanded into macroballoons by feeding said particles into a moving hot air stream.
Claim 8
Dependent Claim
46 words
The process according to claim 1 wherein said aromatic tetracarboxylic acid dianhydride is selected from the group consisting of 3,3', 4,4'-benzophenone tetracarboxylic acid dianhydride, pyromellitic dianhydride, and mixtures thereof, and wherein said oxoimine is selected from the group consisting of caprolactam, 2-pyrrolidone, 2-piperidone and mixtures thereof.
Claim 9
Dependent Claim
23 words
The process according to claim 1 wherein said oxoimine is caprolactam, said reactive solvent is isopropyl alcohol and said diamine is 4,4'-diaminodiphenyl methane.
Claim 10
Dependent Claim
50 words
The process according to claim 1 further including the step of adding a filler to said liquid bonding agent prior to said coating step and wherein said filler is selected from the group consisting of aramid fibers, graphite fibers, glass fibers, carbon fibers, graphite powders, fluorocarbon powders and mixtures thereof.
Claim 11
Dependent Claim
55 words
The process according to claim 1 further including the step of adding from about 2 to 30 weight percent, based on the macroballoon weight, of a fire retardant to said liquid composition prior to said drying step; said fire retardant composition being selected from the group consisting of aluminum trihydrate, antimony oxide and mixtures thereof.
Claim 12
Dependent Claim
32 words
The process according to claim 1 further including the step of adding prior to said drying step from about 1 to 50 weight percent, based on final composite weight, of glass macroballoons.
Claim 13
Dependent Claim
15 words
The process according to claim 11 wherein about 25 weight percent glass macroballoons is added.
Claim 14
Dependent Claim
46 words
The process according to claim 1 further including the step of adding prior to said drying step from about 1 to 50 weight percent, based on final composite weight, of a radar absorbing material selected from the group consisting of graphite, ferrites and metal ceramic compounds.
Claim 15
Dependent Claim
22 words
The process according to claim 13 wherein said microwave absorbing material is ferro titanate, of which about 10 weight percent is added.
Claim 16
Dependent Claim
9 words
The product prepared by the process of claim 1.
Claim 17
Dependent Claim
39 words
The product according to claim 15 wherein said liquid bonding agent is a synthetic resin selected from the group consisting of epoxies, polyesters, polyimides, polyvinyls, synthetic rubber, fluorinated hydrocarbons, chlorinated hydrocarbons, phenolics, ureas, melamines and mixtures and copolymers thereof.
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) | 1987-02-20 | 1987-08-22 | 1988-02-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-02-20 | 1991-08-22 | 1992-02-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-02-20 | 1995-08-22 | 1996-02-21 | $7700.00 | Window Closed / Lapsed |