Expanded perlite/alkali metal silicate insulation material and a process for the production thereof

Claim 2

A thermal insulation material having an average maximum linear shrinkage of 2 % or less at temperatures up to 649°C (1200°F) made by the process of: (a) mixing expanded perlite, alkali silicate, water, up to 15 parts by weight of kaolin clay per 100 parts by weight of expanded perlite and up to 2 parts by weight of an organic fiber per 100 parts by weight of expanded perlite to form a mixture, the alkali metal silicate and water content of said mixture being between 60 and 140 % by weight of the expanded perlite content of said mixture; (b) pressing said mixture in a suitable mold to form a.molded article; and (c) curing and drying said molded article.

Claim 3

The thermal insulation material of claim 1 wherein said alkali metal silicate and.water content of said mixture and said expanded perlite content of said mixture are approximately equal by weight.

Claim 4

The thermal insulation material of claim 1 wherein said alkali metal silicate and water content of said mixture comprises about 70 parts by weight of a sodium silicate solution having a solids content of between 37 and 38 % and about 30 parts by weight of water per 100 parts by weight of expanded perlite.

Claim 5

The thermal insulation material of claim 1 wherein said expanded perlite has a loose bulk density of between 0.04 g/cm 3 (2.5 lbs./ft. 3 ) and 0.07 (4.5 lbs./ft.3).

Claim 6

The thermal insulation material of claim 4 wherein said expanded perlite has a loose bulk densitiy of about 0.048 g/cm 3 (3.0 lbs./ft. 3 ).

Claim 7

The thermal insulation material of claim 1 wherein the amount of kaolin clay is about 5 parts by weight per 100 parts by weight of expanded perlite.

Claim 8

The thermal insulation material of claim 1 wherein said kaolin clay comprises between 45 and 55 % SiO 2 , between 35 and 45 % Al 2 O 3 , up to 0.5 % Fe 2 O 3 , up to 3.5 % TiO 2 , up to 0.6 % CaO, up to 1.0 % MgO, up to 0.3 % Na 2 0, and a loss on ignition of between 12 and 14 %.

Claim 9

The thermal insulation material of claim 7 wherein said kaolin clay comprises about 46.9 % SiO 2 , about 38.2 % Al 2 O 3 , about 0.35 % Fe 2 0 3 , about 1.42 % TiO 2 , about 0.43 % CaO, about 0.58 % MgO, about 0.04 % Na 2 0, and a loss on ignition of about 13.9 %.

Claim 10

The thermal insulation material of claim 1 wherein said alkali metal silicate is sodium silicate having a weight ratio of SiO 2 to Na 2 0 of from about 3:1 to about 4:1.

Claim 11

The thermal insulation material of claim 9 wherein said weight ratio of SiO 2 to Na 2 0 is about 3.22:1.

Claim 12

The thermal insulation material of claim 1 wherein said mixture also includes about 0.5 parts by weight methylcellulose per 100 parts by weight of expanded perlite.

Claim 13

The thermal insulation material of claim 11 wherein said methylcellulose contains between 27.5 and 31.5 % methoxyl group.

Claim 14

The thermal insulation material of claim 1 wherein said organic fiber is a synthetic organic fiber selected from the group of polyester fiber, polypropylene fiber, nylon fiber, and rayon fiber.

Claim 15

The thermal insulation material of claim 1 wherein said organic fiber has a fiber diameter of between 12 and 25 microns.

Claim 16

The thermal insulation material of claim 1 wherein said organic fiber has a length of between 1.27 cm (0.5 inch) and 1.9 cm (0.75 inch).

Claim 17

The thermal insulation material of claim 1 wherein said mixture also includes about 0.5 parts by weight of a silicone liquid per 100 parts of expanded perlite.

Claim 18

The thermal insulation material of claim 16 wherein said silicone liquid is a polydimethyl silicone liquid.

Claim 19

The thermal insulation material of claim 1 wherein said mixture comprises about 100 parts by weight of expanded perlite, about 5 parts by weight of a kaolin clay, about 0.5 parts by weight of a methylcellulose, about 2 parts by -weight of a synthetic organic fiber, about 70 parts by weight of a sodium silicate solution having a solids content of between 37 and 38 %, about 0.5 parts by weight of a polydimethyl silicone liquid, and about 30 parts by weight of water.

Claim 20

The thermal insulation material of claim 1 wherein said molded article is cured and dried at a temperature of between 60°C (140°F) and 76.7°C (170°F).

Claim 21

The thermal insulation material of claim 1 wherein the molded article is cured and dried at a temperature of about 76.7°C (170°F).

Claim 22

The thermal insulation material of claim 1 wherein said material has a bulk density of between 0.12 g/cm 3 und 0.224 g/cm 3 (8 and 14 Ibs./ft. 3 ).

Claim 23

The thermal insulation material of claim 21 wherein said material has a bulk density of between 0.176 and 0.208 g/cm 3 (11 and 13 lbs./ ft. 3 ).

Claim 24

The thermal insulation material of claim 21 wherein said material has a thermal conductivity of 0.50 or less B.t.u. in./hr.ft. 2 °F.

Claim 25

A thermal insulation material made by mixing together expanded perlite and alkali metal silicate solution to form a mixture, pressing said mixture in a suitable mold to form a molded article, and curing and drying said molded article, characterized by adding a small amount of methylcellulose to the expanded perlite/ alkali metal silicate mixture to enhance the strength properties of the material.

Claim 26

A thermal insulation material made by mixing together expanded perlite and alkali metal silicate solution to form a mixture, pressing said mixture in a suitable mold to form a molded article, and curing and drying said molded article, characterized by adding a small amount of methylcellulose to the expanded perlite/ alkali metal silicate mixture to enhance the strength properties of the material.

Claim 27

The thermal insulation material of claim 24 wherein the amount of methylcellulose added is about 0.5 parts by weight per 100 parts by weight of expanded perlite.

Claim 28

The thermal insulation material of claim 24 wherein said methylcellulose contains between 27..5 and 31.5 % methoxyl group.

Claim 29

A thermal insulation material made by mixing together expanded perlite and alkali metal silicate solution to form a mixture, pressing said mixture in a suitable mold to form a molded article, and curing and drying said molded article, characterized by adding a small amount of polydimethyl silicone liquid to the expanded perlite/alkali metal silicate mixture to enhance the water repellency properties of the material.

Claim 30

A thermal insulation material made by mixing together expanded perlite and alkali metal silicate solution to form a mixture, pressing said mixture in a suitable mold to form a molded article, and curing and drying said molded article, characterized by adding a small amount of polydimethyl silicone liquid to the expanded perlite/alkali metal silicate mixture to enhance the water repellency properties of the material.

Claim 31

The thermal insulation material of claim 27 wherein the amount of polydimethyl silicone liquid is about 0.5 parts by weight per 100 parts by weight of expanded perlite-

Claim 32

A coherent rigid, heat stable, low density, low thermal conductivity, strong, impact resistant, water repellent, thermal insolution material, having an average maximum linear shrinkage of 2 % or less at temperatures up to 649°C (1200°F), a compressive strength of 4.9 kg/cm 2 (70 psi) or better, a modulus of rupture of 2.8 kg/cm 2 (40 psi) or better, and retaining its water repellency characteristics up to temperatures of about 482°C (900°F), made by the process of: (a) mixing about 100 parts by weight of expanded perlite, about 5 parts by weight of kaolin clay, about 0.5 parts by weight of methylcellulose, about 2 parts by weight of synthetic organic fiber, about 70 parts by weight of sodium silicate solution having a solids content of between 37 to 38 %, about 0.5 parts by weight of polydimethyl silicone liquid and about 30 parts by weight of water to form a mixture; (b) pressing said mixture in a suitable mold to form a molded article; and (c) curing and drying said molded article at a temperature of about 76.7°C (170°F) for about 24 hours.

Claim 33

A coherent rigid, heat stable, low density, low thermal conductivity, strong, impact resistant, water repellent, thermal insolution material, having an average maximum linear shrinkage of 2 % or less at temperatures up to 649°C (1200°F), a compressive strength of 4.9 kg/cm 2 (70 psi) or better, a modulus of rupture of 2.8 kg/cm 2 (40 psi) or better, and retaining its water repellency characteristics up to temperatures of about 482°C (900°F), made by the process of: (a) mixing about 100 parts by weight of expanded perlite, about 5 parts by weight of kaolin clay, about 0.5 parts by weight of methylcellulose, about 2 parts by weight of synthetic organic fiber, about 70 parts by weight of sodium silicate solution having a solids content of between 37 to 38 %, about 0.5 parts by weight of polydimethyl silicone liquid and about 30 parts by weight of water to form a mixture; (b) pressing said mixture in a suitable mold to form a molded article; and (c) curing and drying said molded article at a temperature of about 76.7°C (170°F) for about 24 hours.

Claim 34

A process for making a thermal insulation material including the steps of mixing together expanded perlite and alkali metal silicate solution to form a mixture, pressing said mixture in a suitable mold to form a molded article, and curing and drying said molded article, characterized by curing and drying said molded article at a temperature of about 76.7°C (170°F) for about 24 hours without humidity control.

Claim 35

A process for making a thermal insulation material including the steps of mixing together expanded perlite and alkali metal silicate solution to form a mixture, pressing said mixture in a suitable mold to form a molded article, and curing and drying said molded article, characterized by curing and drying said molded article at a temperature of about 76.7°C (170°F) for about 24 hours without humidity control.