US4595623A — Fiber-reinforced syntactic foam composites and me…

Claim 1

Independent Claim 78 words

A fiber-reinforced syntactic foam composite having a specific gravity less than 1.0 and a coefficient of thermal expansion of about 25×10 -6 in/in/°F. (45×10 -6 cm/cm/°C.) or less and being suitable for use in the outer space environment, the composite being prepared from an admixture comprising a heat curable thermosetting resin, hollow microspheres having a diameter in the range of about 5 to about 200 micrometers and fibers having a length less than or equal to 250 micrometers.

Claim 2

Dependent Claim 78 words

A fiber-reinforced syntactic foam composite having a specific gravity less than 1.0 and a coefficient of thermal expansion of about 25×10 -6 in/in/°F. (45×10 -6 cm/cm/°C.) or less and being suitable for use in the outer space environment, the composite being prepared from an admixture comprising a heat curable thermosetting resin, hollow microspheres having a diameter in the range of about 5 to about 200 micrometers and fibers having a length less than or equal to 250 micrometers.

Claim 3

Dependent Claim 26 words

The composite of claim 1 wherein the resin comprises a material selected from the group consisting of an epoxy, a polyester and a condensate of formaldehyde.

Claim 4

Dependent Claim 23 words

The composite of claim 2 wherein the heat curable thermosetting resin comprises a mixture of an epoxy resin and a polyfunctional curing agent.

Claim 5

Dependent Claim 13 words

The composite of claim 3 wherein the epoxy resin is tetraglycidyl methylene dianiline.

Claim 6

Dependent Claim 19 words

The composite of claim 3 wherein the epoxy resin comprises a mixture of diglycidyl orthotoluidine and tetraglycidyl methylene dianiline.

Claim 7

Dependent Claim 16 words

The composite of claim 3 wherein the epoxy resin is the diglycidyl ether of Bisphenol A.

Claim 8

Dependent Claim 16 words

The composite of claim 3 wherein the epoxy resin is a phenol formaldehyde novolac polyglycidyl ether.

Claim 9

Dependent Claim 13 words

The composite of claim 3 wherein the polyfunctional curing agent is a polyamine.

Claim 10

Dependent Claim 15 words

The composite of claim 3 wherein the polyfunctional curing agent is a polycarboxylic acid anhydride.

Claim 11

Dependent Claim 19 words

The composite of claim 9 wherein the polycarboxylic acid curing agent is the maleic anhydride adduct of methyl cyclopentadiene.

Claim 12

Dependent Claim 14 words

The composite of claim 3 wherein the mixture further comprises benzyldimethylaniline as an accelerator.

Claim 13

Dependent Claim 28 words

The composite of claim 1 wherein the hollow microspheres are formed of a material selected from the group consisting of glass, silica, carbon, acrylate resins, and phenolic resins.

Claim 14

Dependent Claim 22 words

The composite of claim 12 wherein the hollow microspheres are formed of glass and have an average diameter of about 50 micrometers.

Claim 15

Dependent Claim 18 words

The composite of claim 12 wherein the hollow microspheres comprise a mixture of glass microspheres and carbon microspheres.

Claim 16

Dependent Claim 25 words

The composite of claim 1 wherein the fibers are formed of a material selected from the group consisting of graphite, glass, carbon, nylon, and polyamide.

Claim 17

Dependent Claim 27 words

The composite of claim 15 wherein the fibers are formed of graphite and have a length of about 50 micrometers and a diameter of about 8 micrometers.

Claim 18

Dependent Claim 15 words

The composite of claim 1 wherein said admixture further includes a coupling and wetting agent.

Claim 19

Dependent Claim 12 words

The composite of claim 1 wherein the admixture further includes solid microbeads.

Claim 20

Dependent Claim 48 words

The composite of claim 1 which comprises about 35 to about 65 percent by volume microspheres and about 3 to about 10 percent by volume fibers, the balance being a matrix comprised of the heat cured resin throughout which the microspheres and fibers are dispersed and bonded together.

Claim 21

Dependent Claim 29 words

The composite of claim 19 which additionally comprises about 2 to about 8 percent by volume of solid microbeads having a diameter of about 2 to about 8 micrometers.

Claim 22

Dependent Claim 76 words

The composite of claim 1 wherein: (a) the heat curable thermosetting resin comprises a mixture of diglycidyl orthotoluidene, tetraglycidyl methylene dianiline, nadic methyl anhydride, and benzyldimethylaniline; (b) the hollow microspheres are glass microspheres having a mean diameter of 50 micrometers; (c) the fibers are graphite fibers having a length of about 50 micrometers and a diameter of about 8 micrometers; and (d) the admixture further comprises solid glass microbeads having a median diameter of 3 micrometers.

Claim 23

Dependent Claim 90 words

A fiber-reinforced syntactic foam composite having a specific gravity less than 1.0 and a coefficient of thermal expansion of about 13×10 -6 in/in/°F. (23×10 -6 cm/cm/°C.) or less and being suitable for use in the outer space environment, said composite comprising: (a) a heat curable thermosetting epoxy resin comprising a mixture of tetraglycidyl methylene dianiline, nadic methyl anhydride, and benzyldimethylaniline; (b) hollow glass microspheres having a mean diameter of about 75 micrometers; and (c) graphite fibers having a length of about 150 micrometers and a diameter of about 8 micrometers.

Claim 24

Dependent Claim 90 words

A fiber-reinforced syntactic foam composite having a specific gravity less than 1.0 and a coefficient of thermal expansion of about 13×10 -6 in/in/°F. (23×10 -6 cm/cm/°C.) or less and being suitable for use in the outer space environment, said composite comprising: (a) a heat curable thermosetting epoxy resin comprising a mixture of tetraglycidyl methylene dianiline, nadic methyl anhydride, and benzyldimethylaniline; (b) hollow glass microspheres having a mean diameter of about 75 micrometers; and (c) graphite fibers having a length of about 150 micrometers and a diameter of about 8 micrometers.

Claim 25

Dependent Claim 15 words

An article of manufacture comprising a body formed from the composite material of claim 1.

Claim 26

Dependent Claim 25 words

The article of manufacture set forth in claim 23 which further comprises a layer of electrically conductive material adhered to selected surfaces of the body.

Claim 27

Dependent Claim 19 words

The article of manufacture set forth in claim 24 wherein said article comprises a component in an antenna structure.

Claim 28

Independent Claim 152 words

A method for fabricating a fiber-reinforced syntactic foam composite which comprises the steps of: (a) admixing a heat curable thermosetting resin, hollow microspheres having a diameter in the range of about 5 to about 200 micrometers and fibers having a length less than or equal to 250 micrometers to form a mixture of the resin, microspheres and fibers; and (b) curing the mixture of the resin, microspheres, and fibers in a mold of predetermined geometry to a thermoset state to provide a composite structure containing about 35 to about 65 volume percent microspheres and about 3 to about 10 volume percent fibers disposed throughout the resin matrix, and the resin comprising the balance of the composite, wherein the composite has a specific gravity of less than 1.0 and a coefficient of thermal expansion about 13×10 -6 in/in/°F. (23×10 -6 cm/cm/°C.) or less and is suitable for use in the outer space environment.

Claim 29

Independent Claim 152 words

A method for fabricating a fiber-reinforced syntactic foam composite which comprises the steps of: (a) admixing a heat curable thermosetting resin, hollow microspheres having a diameter in the range of about 5 to about 200 micrometers and fibers having a length less than or equal to 250 micrometers to form a mixture of the resin, microspheres and fibers; and (b) curing the mixture of the resin, microspheres, and fibers in a mold of predetermined geometry to a thermoset state to provide a composite structure containing about 35 to about 65 volume percent microspheres and about 3 to about 10 volume percent fibers disposed throughout the resin matrix, and the resin comprising the balance of the composite, wherein the composite has a specific gravity of less than 1.0 and a coefficient of thermal expansion about 13×10 -6 in/in/°F. (23×10 -6 cm/cm/°C.) or less and is suitable for use in the outer space environment.

Claim 30

Dependent Claim 68 words

The method of claim 26 wherein the admixing comprises: (a) forming a liquid dispersion of the microspheres and fibers in a coupling agent; (b) filtering the dispersion to separate the microspheres and fibers from the liquid as a filtration residue; (c) drying the residue to provide a mixture of microspheres and fibers coated with the coupling agent; and (d) admixing the coated microspheres and fibers with the resin.

Claim 31

Dependent Claim 37 words

The method of claim 27 wherein: (a) the microspheres are hollow glass microspheres; (b) the fibers are graphite fibers; (c) the coupling agent is selected from the group consisting of a silane compound and a titanate compound.

Claim 32

Dependent Claim 23 words

The method of claim 26 wherein the heat curable thermosetting resin is a mixture of an epoxy resin and a polyfunctional curing agent.

Claim 33

Dependent Claim 13 words

The method of claim 29 wherein the epoxy resin is tetraglycidyl methylene dianiline.

Claim 34

Dependent Claim 19 words

The method of claim 29 wherein the epoxy resin comprises a mixture of diglycidyl orthotoluidene and tetraglycidyl methylene dianiline.

Claim 35

Dependent Claim 16 words

The method of claim 29 wherein the epoxy resin is the diglycidyl ether of Bisphenol A.

Claim 36

Dependent Claim 16 words

The method of claim 29 wherein the epoxy resin is a phenol formaldehyde novolac polyglycidyl ether.

Claim 37

Dependent Claim 13 words

The method of claim 29 wherein the polyfunctional curing agent is a polyamine.

Claim 38

Dependent Claim 15 words

The method of claim 29 wherein the polyfunctional curing agent is a polycarboxylic acid anhydride.

Claim 39

Dependent Claim 19 words

The method of claim 35 wherein the polycarboxylic acid curing agent is the maleic anhydride adduct of methyl cyclopentadiene.

Claim 40

Dependent Claim 14 words

The method of claim 29 wherein the mixture further comprises benzyldimethylaniline as an accelerator.

Claim 41

Dependent Claim 12 words

The method of claim 26 wherein the hollow microspheres comprise glass microspheres.

Claim 42

Dependent Claim 11 words

The method of claim 26 wherein the fibers comprise graphite fibers.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1989-06-16	1989-12-16	1990-06-17	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1993-06-16	1993-12-16	1994-06-17	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1997-06-16	1997-12-16	1998-06-17	$7700.00	Window Closed / Lapsed

Fiber-reinforced syntactic foam composites and method of forming same

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