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US4414339A
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Low density, electromagnetic radiation absorption composition
Assignee: LOW CHEMICAL COMPANY
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Filing: 1982-03-15
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Granted: 1983-11-08
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Expires: 2002-03-15
Abstract
Abstract Low density compositions containing colloidal-size particulates of an ELM absorber such as Fe3O4 and a particulate of an ELM attenuator such as carbonyl iron dispersed in a dielectric matrix such as a styrene/butyl acrylate copolymer provide improved absorption of electromagnetic radiations.
Inventors
- 👤 Jitka Solc
- 👤 Robert F. Harris
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 17:09
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/0036; H01F1/0045; H01F1/0063; B; B82; B82Y; B82Y25/00; H01P; H01P1/00; H01P1/24; H01P1/26; H01Q; H01Q17/00; H01Q17/004
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
80 words
An ELM absorption composition comprising (1) a solid dielectric material having dispersed therein (2) a colloidal-size particulate having a maximum dimension less than about 1 micrometer of an absorber for electromagnetic radiation and (3) a particulate of an attenuator for electromagnetic radiation, said composition further characterized by having a density less than 6 grams per cubic centimeter (g/cm 3 ) and substantially all of the particles of the absorber being maintained in a spaced apart relationship by the solid dielectric.
Claim 2
Dependent Claim
80 words
An ELM absorption composition comprising (1) a solid dielectric material having dispersed therein (2) a colloidal-size particulate having a maximum dimension less than about 1 micrometer of an absorber for electromagnetic radiation and (3) a particulate of an attenuator for electromagnetic radiation, said composition further characterized by having a density less than 6 grams per cubic centimeter (g/cm 3 ) and substantially all of the particles of the absorber being maintained in a spaced apart relationship by the solid dielectric.
Claim 3
Dependent Claim
48 words
The composition of claim 1 wherein the composition exhibits a magnetic loss tangent greater than 0.05 and an ELM attenuation of greater than 0.5 decibels per centimeter (dB/cm) when the composition having a thickness of 2 centimeters is exposed to electromagnetic radiation having a frequency of 2 gegahertz.
Claim 4
Dependent Claim
36 words
The composition of claim 2 which has a density in the range from about 1.5 to about 3 g/cm 3 and exhibits a magnetic loss tangent greater than 0.2 and an attenuation greater than 2 dB/cm.
Claim 5
Dependent Claim
31 words
The composition of claim 2 wherein the absorber is an oxide of a magnetic metal and the attenuator is a magnetic metal or an alloy containing at least one magnetic metal.
Claim 6
Dependent Claim
11 words
The composition of claim 4 wherein the magnetic metal is iron.
Claim 7
Dependent Claim
37 words
The composition of claim 5 wherein the absorber is Fe 3 O 4 having a maximum particle dimension less than 1 micrometer and the attenuator is carbonyl iron having an average particle size greater than 1 micrometer.
Claim 8
Dependent Claim
43 words
The composition of claim 6 wherein Fe 3 O 4 has a maximum particle dimension in the range from 0.01 to about 0.7 micrometer and the carbonyl iron has an average particle size in the range from about 2 to about 40 micrometers.
Claim 9
Dependent Claim
48 words
The composition of claim 7 comprising from about 90 to about 15 weight parts of a dielectric synthetic thermoplastic and from about 10 to about 85 weight parts of combined absorber and attenuator wherein the weight ratio of absorber to attenuator is from about 90:10 to about 60:40.
Claim 10
Dependent Claim
14 words
The composition of claim 8 wherein the synthetic thermoplastic is a styrene/butyl acrylate copolymer.
Claim 11
Dependent Claim
27 words
The composition of claim 8 wherein substantially all of the particles of the absorber and attenuator are maintained in a discrete spaced apart relationship by the thermoplastic.
Claim 12
Dependent Claim
29 words
The composition of claim 1 in the form of an aqueous dispersion of (A) the solid dielectric material having the absorber particulate dispersed therein and (B) the attenuator particulate.
Claim 13
Dependent Claim
25 words
The composition of claim 1 wherein the absorber particulate has an average particle diameter within the range of from about 0.05 to about 0.1 micrometer.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-11-07 | 1987-05-09 | 1987-11-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-11-07 | 1991-05-09 | 1991-11-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-11-07 | 1995-05-09 | 1995-11-08 | $7700.00 | Window Closed / Lapsed |