Fire resistant vermiculite composition board and method of manufacture

Claim 2

Fire resistant vermiculite composition board comprising a felted, dried sheet comprising in dispersed admixture: ______________________________________ % by weight ______________________________________ Heat-expanded vermiculite particles 40 to 90 Ceramic clay particles 5 to 20 Hydrated cellulosic gel having a TAPPI drainage time of at least 900 seconds 10 to 30. ______________________________________

Claim 3

Fire resistant vermiculite composition board comprising a felted, dried sheet comprising in dispersed admixture ______________________________________ % by weight ______________________________________ Heat-expanded vermiculite particles 40 to 90 Ceramic clay particles 5 to 20 Hydrated cellulosic gel having a TAPPI drainage time of at least 900 seconds 10 to 30 ______________________________________ the vermiculite being expanded to from 40-98% of its capacity for heat expansion and hence to a degree resulting in its further heat expansion, and accordingly heat expansion of the composition board of which it is a component, upon exposure of the board to fire.

Claim 4

Fire resistant vermiculite composition board comprising a felted, dried sheet comprising in dispersed admixture ______________________________________ % by weight ______________________________________ Heat-expanded vermiculite particles 40 to 90 Ceramic clay particles 5 to 20 Hydrated cellulosic gel having a TAPPI drainage time of at least 900 seconds 10 to 30 ______________________________________ the vermiculite being expanded to from 40-98% of its capacity for heat expansion and hence to a degree resulting in its further heat expansion, and accordingly heat expansion of the composition board of which it is a component, upon exposure of the board to fire.

Claim 5

The composition board of claim 2 wherein the vermiculite is expanded to from 75 to 98% of its capacity for heat expansion.

Claim 6

The composition board of claim 2 wherein the vermiculite content is from 50 to 70% by weight.

Claim 7

The composition board of claim 2 wherein the hydrated cellulosic gel is characterized by a TAPPI drainage time of from 900 to 1,800 seconds.

Claim 8

The compositon board of claim 2 including from 1 to 20% by weight of wood in fibrous form.

Claim 9

The composition board of claim 2 including from 1 to 20% by weight of defiberized wood fibers having a TAPPI freeness of less than 750 C.S.F.

Claim 10

The composition board of claim 2 including from 1 to 20% by weight starch.

Claim 11

The composition board of claim 2 including from 1 to 20% by weight defiberized wood and from 1 to 20% by weight starch.

Claim 12

The composition board of claim 2 wherein at least one outer face of the board is covered with a coating of sodium silicate.

Claim 13

The composition board of claim 2 wherein at least one outer face of the composition board is coated uniformly with a substantially impervious coating of sodium silicate, the coating having a thickness of from 0.001 inch to 0.01 inch.

Claim 14

The composition board of claim 2 wherein the board has a moisture content of less than 1% by weight.

Claim 15

Fire resistant vermiculite composition board comprising a felted, dried sheet containing in dispersed admixture: ______________________________________ % By Weight ______________________________________ Heat-expanded vermiculite particles 50 to 70 Ceramic clay particles 5 to 20 Hydrated cellulosic gel, having a TAPPI drainage time of at least 900 seconds 10 to 30 Wood in fibrous form 1 to 20 Starch 1 to 20 ______________________________________ the vermiculite being expanded to a degree of from 75 to 98% of its capacity for heat expansion, and at least one outer face of the board having substantially uniform, impervious coating of sodium silicate, the coating having a thickness of from 0.001 inch to 0.01 inch.

Claim 16

Fire resistant vermiculite composition board comprising a felted, dried sheet containing in dispersed admixture: ______________________________________ % By Weight ______________________________________ Heat-expanded vermiculite particles 50 to 70 Ceramic clay particles 5 to 20 Hydrated cellulosic gel, having a TAPPI drainage time of at least 900 seconds 10 to 30 Wood in fibrous form 1 to 20 Starch 1 to 20 ______________________________________ the vermiculite being expanded to a degree of from 75 to 98% of its capacity for heat expansion, and at least one outer face of the board having substantially uniform, impervious coating of sodium silicate, the coating having a thickness of from 0.001 inch to 0.01 inch.

Claim 17

The process for the manufacture of fire resistant vermiculite composition board which comprises: a. heating vermiculite to a temperature for a duration predetermined to partially expand the vermiculite to a degree of from 40 to 98% of its capacity for heat expansion, b. forming an aqueous slurry of board-forming consistency comprising: ______________________________________ % by weight ______________________________________ The partially expanded vermiculite of step "a" 40 to 90 Ceramic clay particles 5 to 20 Hydrated cellulosic gel having a TAPPI drainage time of at least 900 seconds 10 to 30 ______________________________________ c. vacuum forming the slurry into a wet sheet on a board-forming screen, and d. drying the sheet.

Claim 18

The process for the manufacture of fire resistant vermiculite composition board which comprises: a. heating vermiculite to a temperature for a duration predetermined to partially expand the vermiculite to a degree of from 40 to 98% of its capacity for heat expansion, b. forming an aqueous slurry of board-forming consistency comprising: ______________________________________ % by weight ______________________________________ The partially expanded vermiculite of step "a" 40 to 90 Ceramic clay particles 5 to 20 Hydrated cellulosic gel having a TAPPI drainage time of at least 900 seconds 10 to 30 ______________________________________ c. vacuum forming the slurry into a wet sheet on a board-forming screen, and d. drying the sheet.

Claim 19

The process of claim 14 including the step of heating the vermiculite under conditions predetermined to expand it to from 75 to 98% of its capacity for heat expansion.

Claim 20

The process of claim 14 including the step of adding to the slurry from 1 to 20 parts by weight starch and thereafter kiln drying the wet sheet in three temperature zones, the first being maintained at from 600° to 700° C., the second at from 450° to 550° C., and the third at from 400° to 500° C.

Claim 21

The process of claim 14 including the step of adding to the slurry from 1 to 20 parts by weight defiberized wood and thereby accellerating the drainage of the slurry on the board-forming screen.

Claim 22

The process of claim 14 including the step of coating at least one face of the dried sheet with a coating of sodium silicate.

Claim 23

The process of claim 14 wherein the sheet is dried to a moisture content of less than 1% by weight.