Patent US3530647A successfully refreshed from Google Patents.
US4469733A
Expired / Lapsed
US
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Foam sandwich construction
Assignee: Unitex Ltd Great Britain
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Filing: 1984-02-06
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Granted: 1984-09-04
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Expires: 2004-02-06
Abstract
Abstract The invention provides a laminate or sandwich suitable for structural purposes and which comprises a lightweight foam core having bonded on one or both sides a lightweight structural skin. More particularly the structural skin adapted to be bonded to the foam core to form the laminate or sandwich construction comprises a composite of resin and monofilaments. This structural skin is characterized in that these monofilaments are laid to extend along the skin without directional change relative to the extent of the skin. The monofilaments are at least 10 cm in length and are neither crimped nor woven. Within the composite forming the structural skin the ratio of resin to monofilament is ess than 2:1 by weight.
Inventors
- 👤 Robert M. Seddon
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 18:08
CPC Classifications
B; B32; B32B; B32B5/00; B32B5/18; C; C08; C08J; C08J9/00; C08J9/36; B29; B29C; B29C44/00; B29C44/02; B29C44/12; B29C70/00; B29C70/04; B29C70/06; B29C70/08; B32B5/22; B32B5/24; B32B5/26; B29K; B29K2105/00; B29K2105/06; C08J2375/00; C08J2375/04; C08J2375/06; Y; Y10; Y10T; Y10T428/00; Y10T428/24; Y10T428/24058; Y10T428/24074; Y10T428/24091; Y10T428/24099; Y10T428/24116; Y10T428/24132; Y10T442/00; Y10T442/60; Y10T442/643; Y10T442/644; Y10T442/647; Y10T442/651
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
217 words
In a foam sandwich structure suitable for use as a load bearing cladding with high stiffness to weight ratio and being of the type in which two skins are resin-bonded, one on each side, to a core of plastics foam material to form the sandwich with said core forming the main means of shear stress transference between the two skins, the improvement comprising: (a) each skin comprising a layer of monofilaments of at least 10 cm in length laid substantially in parallel with one another to extend along the skin, with directional change being kept minimal, said skin monofilaments being non-sinuous and not woven; (b) a mat of randomly arranged monofilaments interposed between the foam core and each adjacent monofilament skin layer; and (c) said filaments of said skin and said mat being bound to one another and to adjacent layers of the sandwich structure by a thermosetting resin, wherein the resin is present in a quantity sufficient to wet the filaments but not in excess, the ratio of resin to monofilament being less than 1.75:1 by weight throughout the layer of monofilaments forming each skin, and the ratio of resin to monofilament being less than 2:1 by weight throughout the sandwich structure as a whole, whereby a sandwich structure of improved load bearing strength is provided.
Claim 2
Dependent Claim
217 words
In a foam sandwich structure suitable for use as a load bearing cladding with high stiffness to weight ratio and being of the type in which two skins are resin-bonded, one on each side, to a core of plastics foam material to form the sandwich with said core forming the main means of shear stress transference between the two skins, the improvement comprising: (a) each skin comprising a layer of monofilaments of at least 10 cm in length laid substantially in parallel with one another to extend along the skin, with directional change being kept minimal, said skin monofilaments being non-sinuous and not woven; (b) a mat of randomly arranged monofilaments interposed between the foam core and each adjacent monofilament skin layer; and (c) said filaments of said skin and said mat being bound to one another and to adjacent layers of the sandwich structure by a thermosetting resin, wherein the resin is present in a quantity sufficient to wet the filaments but not in excess, the ratio of resin to monofilament being less than 1.75:1 by weight throughout the layer of monofilaments forming each skin, and the ratio of resin to monofilament being less than 2:1 by weight throughout the sandwich structure as a whole, whereby a sandwich structure of improved load bearing strength is provided.
Claim 3
Dependent Claim
54 words
A sandwich structure according to claim 1 wherein each said mat comprises glass monofilaments and has a weight of more than 20, but less than 500 grams per square meter and wherein each layer of substantially parallel monofilaments comprises glass monofilaments and is of a weight of at least 500 grams per square meter.
Claim 4
Dependent Claim
38 words
A sandwich structure according to claim 2 wherein the resin and monofilaments are present in the skin and mat of each side of said foam core in a resin to monofilament ratio of less than 1.75:1 by weight.
Claim 5
Dependent Claim
51 words
A sandwich structure according to claim 1 wherein the resin is selected from the group consisting essentially of phenolic resin polyester resin, polyurethane resin and epoxy resin and wherein the monofilaments are selected from the group consisting essentially of glass, carbon, nylon, acrylic resin, aromatic polyamide and metal and combinations thereof.
Claim 6
Dependent Claim
53 words
A sandwich structure according to claim 1, wherein said skins each comprise at least one group of monofilaments laid parallel to one another and formed into a bundle by being bound with light thread to facilitate manipulation of the monofilaments as and before the resin is applied, prior to curing of the resin.
Claim 7
Dependent Claim
53 words
A sandwich structure according to claim 1 wherein to facilitate manipulation as and before the resin is applied and cured, groups of straight monofilaments are laid parallel to one another and pre-fixed to form a layer on one side of a mat of randomly disposed monofilaments which are shorter than said straight monofilaments.
Claim 8
Dependent Claim
44 words
A sandwich structure according to claim 6 wherein each layer of parallel laid monofilaments fixed to one side of the mat is crossed over by another layer of parallel laid monofilaments, all said parallel laid monofilaments being substantially straight, being neither crimped nor woven.
Claim 9
Dependent Claim
22 words
A sandwich structure according to claim 1, wherein the core of foam has a density of at least 75 kg/m 3 .
Claim 10
Dependent Claim
23 words
A sandwich structure according to claim 8, additionally comprising a layer of resin on the outside of at least one of the skins.
Claim 11
Dependent Claim
16 words
A sandwich structure according to claim 9, wherein said layer of resin contains a filler material.
Claim 12
Dependent Claim
59 words
A sandwich structure according to claim 1, wherein said core comprises expanded polyurethane foam having a density of at least 75 kg/m 3 and wherein said sandwich additionally comprises, laid outside each skin, a further layer of monofilaments which are substantially parallel to one another, but at an angle inclined to the parallel filaments in the adjacent underlying layer.
Claim 13
Dependent Claim
72 words
A foam sandwich construction according to claim 11, wherein (a) said mat comprises glass monofilaments, in an amount of 250 to 350 grams per square meter; (b) said skin and said further layer comprise glass monofilaments, in an amount of 500 to 1500 grams per square meter; and (c) said sandwich additionally comprises an outer layer of randomly arranged glass filaments in an amount of 100 to 200 grams per square meter.
Claim 14
Dependent Claim
40 words
A foam sandwich construction according to claim 11, wherein the resin employed to bond the filaments to one another and to adjacent layers is polyester resin and includes a decorative surface coating applied to the outside of the sandwich construction.
Claim 15
Dependent Claim
62 words
A sandwich structure according to claim 1, wherein the structure is adapted to bridge a span between strong points as a cladding, and the non-sinuous monofilaments in the skin bonded at each respective side of the foam core are laid in parallel to bridge the span, the individual monofilaments being continuous and unbroken over the entire span bridged by the sandwich structure.
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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) | 1987-09-04 | 1988-03-05 | 1988-09-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-09-04 | 1992-03-05 | 1992-09-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-09-04 | 1996-03-05 | 1996-09-04 | $7700.00 | Window Closed / Lapsed |