Method for making fire retardant materials and related products
View Patent ↗A method for making fire retardant material including fire retardant cellulosic insulation is described. The method includes an arrangement for adding one or more feedstocks and a fire retardancy chemical compound to a common blend tank prior to feedstock drying. The one or more feedstocks may include at least one virgin pulp stock feed and at least one recycled material stock feed. The amount and type of both the virgin feedstock and the recycled material feedstock is selectable. Old newsprint (ONP) may be one type of recycled material feedstock. Another suitable type of recycled material feedstock is old corrugated containers (OCC). The method further includes retaining the fiber feedstock and the chemical compound together for enough time to ensure adherence or impregnations of enough of the chemical to the fibers after the drying process. Fluffing or fiberizing of the treated fibers may be accomplished under less severe conditions than ordinarily employed when making conventional cellulose insulation.
1. A method for making fire retardant fibers comprising the steps of:
a. introducing one or more fiber feedstocks to a blend tank, wherein each of the one or more fiber feedstocks has a basic structure, and wherein at least one of the one or more fiber feedstocks includes a bonding agent;
b. adding a fire retardant chemical to the blend tank, wherein the fire retardant chemical is a combination of boric acid and borax in liquid form selected to improve the solubility of each of the boric acid and the borax and thereby provide effective attachment of the boric acid and the borax on and into the basic structure of the one or more fiber feedstocks;
c. retaining the one or more fiber feedstocks and the chemical in the blend tank for a period of time sufficient to provide effective attachment of the boric acid and the borax on and into the basic structure of the one or more fiber feedstocks;
d. then drying the fibers of the one or more fiber feedstocks to form a chemically treated pulp cake; and
e. fluffing the pulp cake to form the fire retardant fibers.
2. The method of claim 1 further comprising the step of fiberizing the fire retardant fibers after the fluffing step.
3. The method of claim 1 wherein the fluffing step is performed by introducing the pulp cake to a pair of counter rotating meshed blades to break up the pulp cake into the fire retardant fibers.
4. The method of claim 1 wherein the one or more fiber feedstocks includes a virgin pulp feedstock and one or more recycled material feedstocks.
5. The method of claim 4 wherein there is only one recycled material feedstock and it is old newsprint.
6. The method of claim 5 wherein the ratio of virgin pulp feedstock to old newsprint is in the range of 1% to 50% by weight.
7. The method of claim 1 wherein the fiber feedstock is old corrugated container.
8. The method of claim 1 wherein the combination of borax and boric acid is about 9.4% by weight of the fire retardant fibers.
9. The method of claim 1 further comprising the step of adding a dye to the fire retardant fibers.
10. The method of claim 1 further comprising the step of drying the fire retardant fibers after the fluffing step.
11. The method of claim 1 wherein the fire retardant fibers are dried down to a moisture content of about 14%.
12. The method of claim 1 wherein the one or more fiber feedstocks and the chemical are heated in the blend tank to a temperature of about 120° F.
13. The method of claim 12 wherein the one or more fiber feedstocks and the chemical are retained in the blend tank for about one hour.
14. The method of claim 1 further comprising the step of adding an enzyme to the blend tank to remove the bonding agent from the at least one of the one or more fiber feedstocks and thereby enhance the effective attachment of the combination of fire retardant chemicals on and into the basic structure of the one or more fiber feedstocks.
15. The method of claim 14 wherein the bonding agent has been removed by introducing the enzyme to the blend tank, wherein the enzyme is retained in the blend tank long enough to remove the bonding agent from the at least one of the one or more of the fiber feedstocks.
16. The method of claim 15 wherein the enzyme is an amylase enzyme.
17. The method of claim 15 wherein the bonding agent is one or more of a polysaccharide and a starch.