US3935060A — Fibrous insulation and process for making the same

Claim 1

Independent Claim 186 words

A process for making a fibrous insulation, said process comprising forming a slurry containing by weight about 2.1% to about 7.5% ceramic fibers, about 18% to about 22% colloidal silica binder which is capable of forming a ceramic when fired, not more than about 5.4% ceramic filler, and about 60% to about 80% water; felting the slurry to form a soft felt in which the fibers cross at junction points; precipitating the binder onto the fibers and filler by mixing into the slurry hexamethylenetetramine which generates ammonia at between about 160°F. and 205°F. and heating the soft felt to between about 160°F. and 205°F. for about 60 to about 120 minutes to generate the ammonia so as to elevate the pH of the liquid within the felt to at least about 6.5 and thereby cause the binder to concentrate and gel at the junction points, said heating to between 160°F. and 205°F. being in an enclosure to prevent excessive evaporation of liquid from the soft felt; thereafter subjecting the soft felt to microwave energy to dry the felt; and firing the felt to increase its strength.

Claim 2

Dependent Claim 186 words

A process for making a fibrous insulation, said process comprising forming a slurry containing by weight about 2.1% to about 7.5% ceramic fibers, about 18% to about 22% colloidal silica binder which is capable of forming a ceramic when fired, not more than about 5.4% ceramic filler, and about 60% to about 80% water; felting the slurry to form a soft felt in which the fibers cross at junction points; precipitating the binder onto the fibers and filler by mixing into the slurry hexamethylenetetramine which generates ammonia at between about 160°F. and 205°F. and heating the soft felt to between about 160°F. and 205°F. for about 60 to about 120 minutes to generate the ammonia so as to elevate the pH of the liquid within the felt to at least about 6.5 and thereby cause the binder to concentrate and gel at the junction points, said heating to between 160°F. and 205°F. being in an enclosure to prevent excessive evaporation of liquid from the soft felt; thereafter subjecting the soft felt to microwave energy to dry the felt; and firing the felt to increase its strength.

Claim 3

Dependent Claim 188 words

A process for making a light weight fibrous insulation having a density between approximately 10 lbs./ft. 3 and 38 lbs./ft. 3 , said process comprising: forming a slurry containing by weight about 2.1% to about 7.5% ceramic fibers, about 18% to about 22% colloidal silica binder which is capable of forming a ceramic when fired, no more than about 5.4% ceramic filler of a granular nature, and about 60% to about 80% water; felting the slurry to form a soft felt in which some fibers cross over other fibers to create a network having interstices in which the granules of the filler generally locate and wherein the crossing fibers and the fillers form junction points; causing the binder to concentrate at the junction points and to gel at the junction points by introducing into the soft felt enough ammonia gas to elevate the pH of the liquid within the felt to at least about 6.5; and subjecting the felt to microwave energy to dry the felt such that the drying is substantially uniform throughout so as to prevent the binder from migrating to the surface of the felt.

Claim 4

Dependent Claim 188 words

A process for making a light weight fibrous insulation having a density between approximately 10 lbs./ft. 3 and 38 lbs./ft. 3 , said process comprising: forming a slurry containing by weight about 2.1% to about 7.5% ceramic fibers, about 18% to about 22% colloidal silica binder which is capable of forming a ceramic when fired, no more than about 5.4% ceramic filler of a granular nature, and about 60% to about 80% water; felting the slurry to form a soft felt in which some fibers cross over other fibers to create a network having interstices in which the granules of the filler generally locate and wherein the crossing fibers and the fillers form junction points; causing the binder to concentrate at the junction points and to gel at the junction points by introducing into the soft felt enough ammonia gas to elevate the pH of the liquid within the felt to at least about 6.5; and subjecting the felt to microwave energy to dry the felt such that the drying is substantially uniform throughout so as to prevent the binder from migrating to the surface of the felt.

Claim 5

Dependent Claim 21 words

The process according to claim 2 wherein the slurry further contains a wetting agent which prevents the ceramic fibers from settling.

Claim 6

Dependent Claim 22 words

A process according to claim 2 wherein the fibers are selected from the group consisting of mullite, aluminosilicate, zirconia, silica, and chromia.

Claim 7

Dependent Claim 20 words

A process according to claim 2 wherein the dried felt is fired at a temperature between about 2300°F. and 3200°F.

Claim 8

Dependent Claim 128 words

An insulative material comprising: ceramic fibers disposed in a random network such that some of the fibers cross over other fibers, creating interstices in the network; a granular ceramic filler with the granules thereof being in the interstices of the network, whereby the crossing fibers and the fillers form junction points in the network; and a binder concentrated at the junction points of the fibrous network and holding the fibers and the granules of the filler in place, the binder being silica; the insulative material having a density between approximately 10 lbs./ft. 3 and 38 lbs./ft. 3 with the fibers constituting between approximately 20% and 80% of the weight of the material, the binder between approximately 10% and 40%, and the granular filler not more than approximately 50%.

Claim 9

Dependent Claim 128 words

An insulative material comprising: ceramic fibers disposed in a random network such that some of the fibers cross over other fibers, creating interstices in the network; a granular ceramic filler with the granules thereof being in the interstices of the network, whereby the crossing fibers and the fillers form junction points in the network; and a binder concentrated at the junction points of the fibrous network and holding the fibers and the granules of the filler in place, the binder being silica; the insulative material having a density between approximately 10 lbs./ft. 3 and 38 lbs./ft. 3 with the fibers constituting between approximately 20% and 80% of the weight of the material, the binder between approximately 10% and 40%, and the granular filler not more than approximately 50%.

Claim 10

Dependent Claim 24 words

An insulative material according to claim 6 wherein the ceramic fibers are selected from the group consisting of mullite, aluminosilicate, silica, zirconia, and aluminosilicate-chromia.

Claim 11

Dependent Claim 27 words

An insulative material according to claim 6 wherein the granular filler includes hollow spheres of a material selected from the group consisting of silica, aluminosilicate, and zirconia.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1979-01-26	1979-07-28	1980-01-27	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1983-01-26	1983-07-28	1984-01-27	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1987-01-26	1987-07-28	1988-01-27	$7700.00	Window Closed / Lapsed

Fibrous insulation and process for making the same

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