Flame-retarded paper products and method and apparatus for making them

Abstract

A flame-retarded paper product comprises as a fire-retardant (FR) ingredient a compound selected from among inorganic and organic flame-retardant compounds. A method of making a flame-retarded paper product is described, which comprises: a) producing a base paper; b) applying to the paper base at least one FR compound, to form a layer comprising said compound; and c) applying to the base paper, over said layer, a coating color and/or laminate and/or surface sizing.

1 . A flame-retarded paper product, comprising as a fire-retardant (FR) ingredient a compound selected from among inorganic and organic flame-retardant compounds, particularly ammonium bromide and its mixtures with other ammonium salts, mono- or diammonium phosphate, ammonium polyphosphate, ammonium sulphate, urea, organic brominated flame retardants and their mixtures.  
     
     
         2 . A flame-retarded paper product according to  claim 1  wherein the FR ingredient is ammonium bromide.  
     
     
         3 . A flame-retarded paper product according to  claim 1  or  2  wherein the concentration of the ammonium bromide solution is between 10 w/w % to 90 w/w %.  
     
     
         4 . A flame-retarded paper product according to any one of  claims 1  to  3  comprising a flame-retardant or flame-retardant mixture in an amount of between 0.01% by weight of the paper to about 10% by weight of the paper, on a dry basis.  
     
     
         5 . A flame-retarded paper product according to  claim 4  wherein the flame-retardant is present in an amount of between 1.5% by weight of the paper to about 4% by weight of the paper, on a dry basis.  
     
     
         6 . A flame-retarded paper product according to  claim 1 , which comprises a base paper, a layer of an FR compound or compounds, preferably including a first binder, and an uppermost layer of a coating color.  
     
     
         7 . A flame-retarded paper product according to  claim 6 , wherein the first binder is starch.  
     
     
         8 . A flame-retarded paper product according to  claim 6 , wherein the coating color layer comprises a second binder.  
     
     
         9 . Method of making a flame-retarded paper product, which method comprises: a) producing a base paper; b) applying to the paper base at least one FR compound, to form a layer comprising said compound; and c) applying to the base paper, over said layer, a coating color and/or laminate and/or surface sizing.  
     
     
         10 . Method of making a flame-retarded paper product according to  claim 9 , which comprises applying the at least one FR compound preferably by on the base paper a liquid phase comprising the FR compound and a first binder.  
     
     
         11 . Method of making a flame-retarded paper product according to  claim 10 , wherein the first binder is starch.  
     
     
         12 . Method of making a flame-retarded paper product according to  claim 9 , further comprising drying the FR compound layer before applying the coating color.  
     
     
         13 . Method of making a flame-retarded paper product according to  claim 9 , wherein the coating color comprises a second binder and a pigment or pigments, and is applied by passing the paper with the FR compound layer through a bath or by spreading it onto said paper.  
     
     
         14 . Method of making a flame-retarded paper product according to  claim 9 , comprising controlling the thickness of the coating color layer.  
     
     
         15 . Method of making a flame-retarded paper product according to  claim 9 , wherein after drying the FR compound layer is located between the base paper and the coating color layer, and said coating color layer has a thickness of about 5 to about 30 μm.  
     
     
         16 . Method of making a flame-retarded paper product according to  claim 9 , wherein the flame retardant is provided in an aqueous solution.  
     
     
         17 . Method of making a flame-retarded paper product according to  claim 16 , wherein the flame retardant aqueous solution is a solution of ammonium bromide having a concentration from 10 w/w % to 90 w/w %.  
     
     
         18 . Method of making a flame-retarded paper product according to  claim 17 , wherein the concentration of the ammonium bromide solution is between 20 w/w % to about 40 w/w %.  
     
     
         19 . Method of making a flame-retarded paper product according to  claim 9 , wherein the quantity of the FR compound sprayed onto the base paper is from 0.01% by weight of the paper to 10% by weight of the paper.  
     
     
         20 . Method of making a flame-retarded paper product according to  claim 12 , wherein the paper is dried at temperatures between 20° C. to about 90° C.  
     
     
         21 . Use of ammonium bromide as a flame-retarding agent coating layer for paper.  
     
     
         22 . Improvement to paper coating machines, which comprises adding a spraying device provided with nozzles to said machines before the coating unit.  
     
     
         23 . Improvement to paper coating machines, which comprises adding a dispersion-applying device to said machines before the coating unit.  
     
     
         24 . Improvement to paper coating machines according to  claim 15 , further comprising adding a dryer between the spraying device and the coating unit.