Method for adding chemicals to a nonwoven material

Abstract

A method of adding a chemical additive to a fiber web of nonwoven material including cellulose pulp fibers and synthetic fibers and/or filaments. A hydrojet liquid including the chemical additive is used in at least one hydrojet treatment step, which includes at least one vacuum collecting box. The hydrojet liquid is applied to the fiber web for penetrating the fiber web at a pressure of at least 5 bar but not more than 100 bar, in such a manner so that the chemical additive is penetrated into the fiber to fiber intersections of the nonwoven material.

1 . Method of adding a chemical additive to a fiber web of nonwoven material comprising cellulose pulp fibers and synthetic fibers and/or filaments, the method comprising: using a hydrojet liquid comprising the chemical additive in at least one hydrojet treatment step, which comprises at least one vacuum collecting box; said hydrojet liquid being applied to the fiber web to penetrate the fiber web at a pressure of at least 5 bar but not more than 100 bar, such that the chemical additive is penetrated into the fiber to fiber intersections of the nonwoven material.  
     
     
         2 . The method according to  claim 1 , wherein the hydrojet liquid is applied at a pressure of at least 20 bar but not more than 80 bar.  
     
     
         3 . The method according to  claim 1 , wherein the hydrojet liquid is applied at a pressure of at least 20 bar but not more than 60 bar.  
     
     
         4 . The method according to  claim 1 , wherein the hydrojet liquid is applied at a pressure of at least 20 bar but not more than 40 bar.  
     
     
         5 . The method according to  claim 1 , wherein the hydrojet liquid used in the hydrojet treatment step for penetrating the fiber web is applied in an amount such that exchangeable water within the fiber web is replaced by the hydrojet liquid, whereby the fiber web is saturated with the hydrojet liquid comprising the chemical additive.  
     
     
         6 . The method according to  claim 1 , wherein the hydrojet liquid is applied in an amount corresponding to at least about 2 gram of water per gram of dry fiber web material weight, but not more than about 10 gram of water per gram of dry fiber web material weight.  
     
     
         7 . The method according to  claim 1 , wherein the chemical additive is selected from one or more of the following groups: wet or dry strength agents, lint-preventing agents, copolymer dispersions, latex, debonders or softeners, or mixtures thereof.  
     
     
         8 . The method according to  claim 1 , wherein the hydrojet liquid is a dilute solution comprising the chemical additive, which is mixed with water before it penetrates the fiber web.  
     
     
         9 . The method according to  claim 1 , wherein the fiber web comprises at least about 20% dry weight of cellulose fibers.  
     
     
         10 . The method according to  claim 1 , wherein the synthetic fibers and/or filaments comprise synthetic staple fibers and/or continuous filaments.  
     
     
         11 . The method according to  claim 1 , further comprising one or more hydroentanglement steps of which at least one precedes the hydrojet treatment step in which the penetration of the fiber web with the hydrojet liquid comprising the chemical additive takes place.  
     
     
         12 . The method according to  claim 1 , further comprising one or more hydroentanglement steps of which there is one main hydroentanglement step, which in turn comprises one or more hydroentanglement steps, and that the penetration of the fiber web with the hydrojet liquid comprising the chemical additive takes place in a hydrojet treatment step subsequent to the main hydroentanglement step.  
     
     
         13 . The method according to  claim 11 , further comprising a dewatering step between the preceding hydroentanglement step or steps and the subsequent hydrojet treatment step.  
     
     
         14 . The method according to  claim 12 , further comprising a dewatering step between the preceding hydroentanglement step or steps and the subsequent hydrojet treatment step.