Dispersible non-wood pulp

Abstract

Disclosed are non-wood pulps having a fiber length greater than about 1.70 mm and a Very Long Fiber (VLF) content of about 0.50% or less. The fibers are readily dispersible in water and useful in the formation of fibrous sheets, particularly wet-laid sheets and more particularly wet-laid tissue sheets having a relatively low basis weight. In addition of having a relatively long fiber length and a low VLF content, the pulps may also have a Dispersivity Index of about 2.00 or less, which is indicative of a relatively narrow fiber length distribution. The pulps may be prepared from plants of the family Asparagaceae by mechanical pulping and more preferably by a chemi-mechanical pulping process using an alkaline and hydrogen peroxide where the plant biomass is cut to size prior to pulping.

We claim: 
     
         1 . A method of manufacturing a non-wood pulp comprising the steps of: (a) providing a non-wood biomass derived from a plant of the family Asparagaceae; (b) cutting the non-wood biomass to a nominal length; (c) extracting water soluble solids from the cut biomass to produce a bagasse; (d) impregnating the bagasse with a caustic solution and maintaining the impregnation for a first reaction time to produce an impregnated bagasse; and (e) refining the impregnated bagasse under first refining conditions to produce a primary pulp. 
     
     
         2 . The method of  claim 1  wherein the non-wood biomass is cut to a nominal length of about 20 mm or less. 
     
     
         3 . The method of  claim 1  wherein the non-wood biomass is cut to a nominal length from about 5 mm to about 20 mm. 
     
     
         4 . The method of  claim 1  further comprising the steps of cleaning the primary pulp and bleaching the primary pulp using a chlorine free bleaching agent. 
     
     
         5 . The method of  claim 1  wherein the caustic solution comprises a sodium hydroxide alkaline peroxide solution. 
     
     
         6 . The method of  claim 1  wherein the caustic solution comprises sodium hydroxide, peroxide, and a stabilizer. 
     
     
         7 . The method of  claim 1  wherein the step of refining comprises feeding the impregnated bagasse into a refiner having an inlet and a rotating disc within a superatmospheric casing and maintaining the superatmospheric casing at a pressure of at least about 240 kP. 
     
     
         8 . The method of  claim 7  wherein the impregnated bagasse has a consistency from about 20 to about 60%. 
     
     
         9 . The method of  claim 1  further comprising the steps of delivering the primary pulp through a blow valve to a blow line and adding a sodium hydroxide alkaline peroxide solution to the stream of primary pulp in the blow line. 
     
     
         10 . The method of  claim 9  wherein the primary pulp temperature is at least about 80° C. 
     
     
         11 . The method of  claim 9  further comprising the step of mixing the sodium hydroxide alkaline peroxide solution and the primary pulp in the blow line to form a reaction mixture. 
     
     
         12 . The method of  claim 9  further comprising the steps of cleaning the primary pulp to yield a cleaned primary pulp and delivering the cleaned primary pulp to a bleaching vessel and adding a second sodium hydroxide alkaline peroxide solution to the cleaned primary pulp in the bleaching vessel.