Spray-applied cellulose insulation and method

Abstract

A spray-on cellulose insulation and method of application is described herein. The insulation comprises cellulose and an adhesive having gelling properties during application, preferably polyvinyl alcohol. The cellulose includes an additive that triggers gelling of the adhesive upon application to the cellulose. The cellulose preferably also includes a crosslinker for the adhesive. The additive and the crosslinker may be the same, which means the crosslinker is sufficiently alkaline to also trigger the gelling of the adhesive upon application of the adhesive to the cellulose. The gelling of the adhesive allows a reduction in the level of moisture added to the cellulose fibres to below 20%, resulting in an insulation with rapid drying times, reduced risk for fungal growth, lower applied densities and a total moisture content below 30% on an oven dry basis.

1 . Cellulose fibre insulation for use in wall cavities, comprising cellulose fibres and an aqueous adhesive mixture for binding the fibres at application, wherein the moisture content of the cellulose fibre insulation at application is less than 30% on an oven dry weight basis.  
   
   
       2 . The cellulose fibre insulation of  claim 1 , wherein the moisture content is 10-30% on an oven dry weight basis.  
   
   
       3 . The cellulose fibre insulation of  claim 2 , wherein the moisture content is 15-25% on an oven dry weight basis.  
   
   
       4 . The cellulose fibre insulation of  claim 2 , wherein the moisture content is less than 20% on an oven dry weight basis.  
   
   
       5 . The cellulose fibre insulation of  claim 1 , wherein the adhesive used has gelling properties and the cellulose fibres are treated with an additive which leads to a gelling of the adhesive resin on application to the cellulose fibres.  
   
   
       6 . The cellulose fibre insulation of  claim 1 , wherein the adhesive contains polyvinyl alcohol.  
   
   
       7 . The cellulose fibre insulation of  claim 5 , wherein the additive is an alkaline crosslinker.  
   
   
       8 . The cellulose fibre insulation of  claim 7 , wherein the additive is a borate having an alkaline pH in solution.  
   
   
       9 . The cellulose fibre insulation of  claim 5 , wherein the cellulose fibres are treated with a mixture of an acidic crosslinker and an alkaline compound, the mixture having an alkaline pH in solution.  
   
   
       10 . The cellulose fibre insulation of  claim 9 , wherein the alkaline compound is an alkali earth metal hydroxide, oxide, bicarbonate; carbonate or organic base.  
   
   
       11 . The cellulose fibre insulation of  claim 8 , wherein the additive is selected from the group consisting of ammonium pentaborate, ammonium tetraborate and ammonium biborate.  
   
   
       12 . The cellulose fibre insulation of  claim 8 , wherein the crosslinker is an alkali earth metal borate having an alkaline pH in solution.  
   
   
       13 . The cellulose fibre insulation of  claim 12 , wherein the alkali earth metal borate is sodium pentaborate.  
   
   
       14 . The cellulose fibre insulation of  claim 5 , wherein the concentration of the additive in the treated cellulose fibres is 1-15% (w/w).  
   
   
       15 . The cellulose fibre insulation of  claim 13  wherein the concentration of the additive is 5-10%.  
   
   
       16 . The cellulose fibre insulation of  claim 1 , wherein the solids concentration of the aqueous adhesive mixture is 1-15% (w/w).  
   
   
       17 . The cellulose fibre insulation of  claim 1 , wherein the solids concentration of the aqueous adhesive mixture is 5-10% (w/w).  
   
   
       18 . The cellulose fibre insulation of  claim 6 , wherein the aqueous adhesive resin is a mixture comprising polyvinyl alcohol and polyvinyl acetate.  
   
   
       19 . The cellulose fibre insulation of  claim 18 , wherein the aqueous adhesive resin mixture comprises from 1 to 10 parts polyvinyl acetate to 1 part polyvinyl alcohol.  
   
   
       20 . The cellulose fibre insulation of  claim 18 , wherein the aqueous adhesive resin mixture comprises from 1 to 5 parts polyvinyl acetate to 1 part polyvinyl alcohol  
   
   
       21 . The cellulose fibre insulation of  claim 18 , wherein the aqueous adhesive resin mixture comprises 3 parts polyvinyl acetate to 1 part polyvinyl alcohol.  
   
   
       22 . The cellulose fibre insulation of claims  16 , wherein said insulation has a final dry adhesive content of 0.25-3% (w/w).  
   
   
       23 . The cellulose fibre insulation of  claim 22 , wherein said insulation has a final dry adhesive content of 1-2% (w/w).  
   
   
       24 . The cellulose fibre insulation of  claim 1 , further comprising boric acid as a fire retardant and crosslinker.  
   
   
       25 . The cellulose fibre insulation of  claim 1 , wherein the total amount of added water is between 5 and 24%.  
   
   
       26 . A cellulose fibre insulation for use in wall cavities, comprising cellulose fibres and an aqueous adhesive resin for binding the fibres at application, wherein the density of the insulation is between 16.0 to 24.0 kg/m 3  (1.0 and 2.0 lb/ft 3 ).  
   
   
       27 . The cellulose fibre insulation of  claim 24 , wherein said the density of the insulation is less than 24.0 kg/m 3  (1.5 lb./ft 3 ).  
   
   
       28 . A method of insulating a wall surface with an aqueous adhesive-bonded cellulose material, comprising the steps of: 
 treating cellulose fibres with an additive which causes a gelling of the adhesive upon contact, and    mixing the treated cellulose fibres with the adhesive during spray application of the cellulose fibres onto the surface to form a cellulose fibre insulation on the surface, wherein the amount of aqueous adhesive in the cellulose fibre insulation is selected to achieve a moisture content in the insulation of less than 30% on an oven dry weight basis.    
   
   
       29 . The method of  claim 26 , wherein the additive is an alkaline compound.  
   
   
       30 . The method of  claim 27 , wherein the additive is an alkaline borate, rendering the pH of the adhesive alkaline upon contact with the cellulose.  
   
   
       31 . The method of  claim 26 , wherein the cellulose is further treated with an acidic crosslinker and the additive is an alkaline compound added is a sufficient amount to render the adhesive alkaline upon contact with the cellulose.  
   
   
       32 . The method of  claim 27 , wherein the alkaline compound is an alkali earth metal hydroxide, oxide, carbonate or organic base.  
   
   
       33 . The method of  claim 28 , wherein the additive is selected from the group of ammonium pentaborate, ammonium tetraborate and ammonium diborate.  
   
   
       34 . The method of  claim 29 , wherein the crosslinker is an alkaline earth metal borate.  
   
   
       35 . The method of  claim 32 , wherein the alkaline earth metal borate is sodium pentaborate.  
   
   
       36 . The method of  claim 26 , wherein the concentration of the additive in the treated cellulose fibres is 1-15% (w/w).  
   
   
       37 . The method of  claim 34 , wherein the concentration of the additive in the treated cellulose fibres is 5-10% (w/w).  
   
   
       38 . The method of  claim 26 , wherein the solids concentration of the aqueous adhesive mixture in the insulation is 1-15% (w/w).  
   
   
       39 . The method of  claim 36 , wherein the solids concentration of the aqueous adhesive mixture is 5-10% (w/w).  
   
   
       40 . The method of  claim 26 , wherein the aqueous adhesive resin is a mixture of polyvinyl alcohol and polyvinyl acetate.  
   
   
       41 . The method of  claim 38 , wherein the aqueous adhesive resin mixture comprises from 1 to 10 parts polyvinyl acetate to 1 part polyvinyl alcohol.  
   
   
       42 . The method of  claim 38 , wherein the aqueous adhesive resin mixture comprises from 1 to 5 parts polyvinyl acetate to 1 part polyvinyl alcohol.  
   
   
       43 . The method of  claim 38 , wherein the aqueous adhesive resin mixture includes 3 parts polyvinyl acetate to 1 part polyvinyl alcohol.  
   
   
       44 . The method of  claim 26 , wherein the final dry adhesive content is 0.25-3% (w/w).  
   
   
       45 . The method of  claim 26 , wherein the final dry adhesive content is 1-2% (w/w).  
   
   
       46 . The method of  claim 26 , wherein the cellulose insulation has an applied density between 16.0 to 24.0 kg/m 3  (1.0 and 2.0 lb/ft 3 ).  
   
   
       47 . The method of  claim 44 , wherein the cellulose insulation has an applied density of less than 24.0 kg/m 3  (1.5 lb./ft 3 ).  
   
   
       48 . The cellulose fibre insulation of  claim 40 , wherein the total amount of added water is between 10 and 20%.