Extruded Granular Absorbent

Abstract

Extruded granular sorbent formed of sorbent granules each being or including an extruded pellet containing water soluble binder sufficient to self-clump when wetted producing clumps of granules each having a clump retention rate of at least 90% and which shrink after clump formation during drying producing a nonstick clump that condenses pulling away from any contacting solid surface minimizing adhesion therebetween. Such clumps preferably also have a crush strength of at least 15 PSI when dry. Pellets preferably contain cold water-soluble amylopectin binder that not only solubilizes when wetted to facilitate clumping but which also opens the interior of the pellet improving absorption capacity. Sorbent well suited for use as litter is formed of granules or pellets having sizes falling within a plurality of different size ranges with the smaller sized fines causing the clumps to form on top of the litter extending generally horizontally along the litter.

What is claimed is: 
     
         1 . A method of making extruded granular sorbent comprising:
 (a) providing an extruder and a starch-containing admixture having a moisture content of no greater than 30% by weight;   (b) subjecting the starch-containing admixture in the extruder to a pressure of at least 1,000 pounds per square inch at a temperature of at least 125° Celsius and which modifies at least some of the starch in the starch-containing admixture into a cold-water soluble binder that is soluble in water at room temperature; and   (c) extruding starch-containing absorbent pellets from the extruder each comprised of the cold-water soluble binder which forms a flowable adhesive when wetted with water at room temperature, the flowable adhesive having a viscosity of (i) at least 200 centipoise within one second after wetting with the room temperature water, (ii) at least 300 centipoise after one second and within five seconds after wetting with the room temperature water, and (iii) at least 400 centipoise after five seconds and within 10 seconds after wetting with the room temperature water, where the viscosity of the flowable adhesive is measured with a Brookfield DV3T viscometer at a spindle rotation of 50 RPM.   
     
     
         2 . The method of  claim 1 , wherein the flowable adhesive becomes a gel as the viscosity of the flowable adhesive increases after wetting of the extruded starch-containing pellets with the room temperature water. 
     
     
         3 . The method of  claim 2 , wherein the flowable adhesive becomes a flowable adhesive gel as the viscosity increases after wetting of the extruded starch-containing pellets with the room temperature water. 
     
     
         4 . The method of  claim 3 , wherein the flowable adhesive gel adheres together at least plurality of pairs of the extruded starch-containing absorbent pellets wetted with the room temperature water thereby forming a clump comprised of the wetted extruded starch-containing absorbent pellets. 
     
     
         5 . The method of  claim 4 , where the clump has a clump retention rate of at least 99%. 
     
     
         6 . The method of  claim 4 , further comprising the step of air drying the clump at least five days until the clump has a moisture content of no more than 20% by dried clump weight, the dried clump having a clump retention rate of at least 97%. 
     
     
         7 . The method of  claim 4 , further comprising the step of air drying the clump at least five days until the clump has a moisture content of no more than 20% by dried clump weight, the dried clump having a crush strength of at least 40 PSI. 
     
     
         8 . The method of  claim 4 , wherein the cold-water soluble binder is comprised of starch modified during extrusion into having a molecular weight of between 8×10 4  and 10 6  g/mol. 
     
     
         9 . The method of  claim 4 , wherein the cold-water soluble binder is comprised of starch modified during extrusion into having a degree of polymerization of between 500 and 6,000 glucose units. 
     
     
         10 . The method of  claim 4 , wherein the cold-water soluble binder is comprised of starch modified during extrusion into having a degree of polymerization of between 500 and 6,000 glucose units and a molecular weight of between 8×10 4  and 10 6  g/mol. 
     
     
         11 . The method of  claim 4 , wherein the cold-water soluble binder in each one of the extruded starch-containing absorbent pellets has a molecular weight within ±25% of 504.43708 g/mol. 
     
     
         12 . The method of  claim 4 , wherein the cold-water soluble binder in each one of the extruded starch-containing absorbent pellets has a mean molecular weight within ±25% of the mean molecular weight of dextrin. 
     
     
         13 . The method of  claim 4 , wherein the starch-containing admixture is comprised of unmodified amylopectin starch and wherein the cold-water soluble binder in each one of the extruded starch-containing absorbent pellets is comprised of a water-soluble amylopectin binder having a molecular weight less than that of the unmodified amylopectin starch in the starch-containing admixture from which each one of the extruded starch-containing absorbent pellets are extruded. 
     
     
         14 . The method of  claim 13 , wherein the cold-water soluble binder is comprised of a reduced molecular weight amylopectin having a molecular weight of between 8×10 4  and 10 6  g/mol. 
     
     
         15 . The method of  claim 1 , wherein the extruded granular sorbent is comprised of: (i) a plurality of pairs of a larger sized extruded starch-containing absorbent pellets, and (ii) a plurality of a finely sized extruded starch-containing absorbent pellets having a size smaller than the larger sized extruded starch-containing absorbent pellets, and wherein, when wetted with the room temperature water, a clump is formed comprised of (i) a plurality of pairs of the larger sized extruded starch-containing absorbent pellets, and (ii) a plurality of pairs of the finely sized extruded starch-containing absorbent pellets, the clump extending in a generally horizontal direction. 
     
     
         16 . The method of  claim 15 , wherein (a) each one of the larger sized extruded starch-containing absorbent pellets have a size (i) no greater than 4 mm in length, width, or diameter, and (ii) no smaller than 2 mm in length, width, or diameter, and (b) each one of the finely sized extruded starch-containing absorbent pellets have a size smaller than 2 mm in length, width, or diameter; and wherein wetting with the room temperature water (i) the plurality of pairs of the finely sized extruded starch-containing absorbent pellets, and (ii) the plurality of pairs of the larger sized extruded starch-containing absorbent pellets forms a clump thereof that extends in a generally horizontal direction. 
     
     
         17 . The method of  claim 16 , wherein the extruded granular sorbent clump comprises a litter, and wherein the clump forms on top of the litter. 
     
     
         18 . The method of  claim 17 , wherein the litter comprises cat litter or animal litter. 
     
     
         19 . The method of  claim 1 , wherein 400 grams of the extruded starch-containing absorbent pellets wetted with 200 grams of the room temperature water and forming the flowable adhesive from the cold-water soluble binder therein, the flowable adhesive having a viscosity of (i) at least 200 centipoise within one second after wetting of the 400 grams of the extruded starch-containing absorbent pellets with the 200 grams of the room temperature water, (ii) at least 300 centipoise after one second and within five seconds after wetting of the 400 grams of the extruded starch-containing absorbent pellets with the 200 grams of the room temperature water, and (iii) at least 400 centipoise after five seconds and within 10 seconds after wetting of the 400 grams of the extruded starch-containing absorbent pellets with the 200 grams of the room temperature water, where the viscosity of the flowable adhesive is measured with the Brookfield DV3T viscometer at the spindle rotation of 50 RPM. 
     
     
         20 . The method of  claim 19 , wherein the room temperature water has a temperature of between 68° Fahrenheit and 74° Fahrenheit. 
     
     
         21 . The method of  claim 1 , comprising the further steps of:
 (d) wetting the extruded starch-containing absorbent pellets with the room temperature water causing the cold-water soluble binder therein to form the flowable adhesive; and   (e) measuring the viscosity of the flowable adhesive with the Brookfield DV3T viscometer at the spindle rotation of 50 RPM, the flowable adhesive having a viscosity of (i) at least 200 centipoise within one second after wetting with the water, (ii) at least 300 centipoise after one second and within five seconds after wetting with the water, and (iii) at least 400 centipoise after five seconds and within 10 seconds after wetting with the water, where the viscosity of the flowable adhesive is measured with a Brookfield DV3T viscometer at a spindle rotation of 50 RPM.   
     
     
         22 . The method of  claim 21 , wherein during the wetting step (d), 400 grams of the extruded starch-containing absorbent pellets are wetted with 200 grams of the room temperature water. 
     
     
         23 . The method of  claim 22 , wherein the room temperature water has a temperature of between 68° Fahrenheit and 74° Fahrenheit. 
     
     
         24 . The method of  claim 1  wherein when the extruded starch-containing absorbent pellets are wetted with the room temperature water and forms the flowable adhesive, the flowable adhesive has a viscosity of (i) at least 400 centipoise within one second after wetting with the room temperature water, (ii) at least 500 centipoise after one second and within five seconds after wetting with the room temperature water, and (iii) at least 700 centipoise after five seconds and within ten seconds after wetting with the room temperature water, the viscosity of the flowable adhesive measured with the Brookfield DV3T viscometer at the spindle rotation of 50 RPM. 
     
     
         25 . The method of  claim 1  wherein when the extruded starch-containing absorbent pellets are wetted with the room temperature water and forms the flowable adhesive, the flowable adhesive has a viscosity of (i) at least 400 centipoise within one second after wetting with the room temperature water, (ii) at least 500 centipoise after one second and within five seconds after wetting with the room temperature water, (iii) at least 700 centipoise after five seconds and within ten seconds after wetting with the room temperature water, and (iv) at least 1000 centipoise after ten seconds and within twenty seconds after wetting with the water, the viscosity of the flowable adhesive measured with the Brookfield DV3T viscometer at the spindle rotation of 50 RPM. 
     
     
         26 . The method of  claim 1  wherein when the extruded starch-containing absorbent pellets are wetted with the room temperature water and forms the flowable adhesive, the flowable adhesive has a viscosity of (i) at least 400 centipoise within one second after wetting with the room temperature water, (ii) at least 500 centipoise after one second and within five seconds after wetting with the room temperature water, (iii) at least 700 centipoise after five seconds and within ten seconds after wetting with the room temperature water, (iv) at least 1000 centipoise after ten seconds and within twenty seconds after wetting with the room temperature water, and (v) at least 1800 centipoise after twenty seconds and within twenty-five seconds after wetting with the room temperature water, the viscosity of the flowable adhesive measured with the Brookfield DV3T viscometer at the spindle rotation of 50 RPM. 
     
     
         27 . The method of  claim 1  wherein when the extruded starch-containing absorbent pellets are wetted with the room temperature water and forms the flowable adhesive, the flowable adhesive has a viscosity of (i) at least 400 centipoise within one second after wetting with the room temperature water, (ii) at least 500 centipoise after one second and within five seconds after wetting with the room temperature water, (iii) at least 700 centipoise after five seconds and within ten seconds after wetting with the room temperature water, (iv) at least 1000 centipoise after ten seconds and within twenty seconds after wetting with the room temperature water, (v) at least 1800 centipoise after twenty seconds and within twenty-five seconds after wetting with the room temperature water, and (vi) at least 2500 centipoise after twenty-five seconds and within thirty seconds after wetting with the room temperature water, the viscosity of the flowable adhesive measured with the Brookfield DV3T viscometer at the spindle rotation of 50 RPM. 
     
     
         28 . The method of  claim 1  wherein when the extruded starch-containing absorbent pellets are wetted with the room temperature water and forms the flowable adhesive, the flowable adhesive has a viscosity of (i) at least 400 centipoise within one second after wetting with the room temperature water, (ii) at least 500 centipoise after one second and within five seconds after wetting with the room temperature water, (iii) at least 700 centipoise after five seconds and within ten seconds after wetting with the room temperature water, (iv) at least 1000 centipoise after ten seconds and within twenty seconds after wetting with the room temperature water, (v) at least 1800 centipoise after twenty seconds and within twenty-five seconds after wetting with the room temperature water, (vi) at least 2500 centipoise after twenty-five seconds and within thirty seconds after wetting with the room temperature water, and (vii) at least 5000 centipoise after thirty seconds and within forty seconds after wetting with the room temperature water, the viscosity of the flowable adhesive measured with the Brookfield DV3T viscometer at the spindle rotation of 50 RPM. 
     
     
         29 . The method of  claim 1 , wherein 200 grams of the extruded starch-containing absorbent pellets wetted with 200 grams of the room temperature water thereby forming the flowable adhesive from the cold-water soluble binder therein, the flowable adhesive having a viscosity of (i) at least 400 centipoise within one second after wetting with the room temperature water, (ii) at least 500 centipoise after one second and within five seconds after wetting with the room temperature water, (iii) at least 700 centipoise after five seconds and within ten seconds after wetting with the room temperature water, (iv) at least 1000 centipoise after ten seconds and within twenty seconds after wetting with the room temperature water, (v) at least 1800 centipoise after twenty seconds and within twenty-five seconds after wetting with the room temperature water, (vi) at least 2500 centipoise after twenty-five seconds and within thirty seconds after wetting with the room temperature water, and (vii) at least 5000 centipoise after thirty seconds and within forty seconds, after wetting with the room temperature water, the viscosity of the flowable adhesive measured with the Brookfield DV3T viscometer at the spindle rotation of 50 RPM. 
     
     
         30 . The method of  claim 29 , wherein the room temperature water has a temperature of between 68° Fahrenheit and 74° Fahrenheit. 
     
     
         31 . The method of  claim 1 , wherein each one of the extruded starch-containing pellets is comprised of at least 12% of the cold-water soluble binder by extruded starch-containing pellet weight. 
     
     
         32 . The method of  claim 31 , wherein at least during step (b) the starch-containing admixture in the extruder is subjected to a pressure of at least 1,200 pounds per square inch at a temperature of at least 135° Celsius. 
     
     
         33 . A method of making extruded granular sorbent comprising:
 (a) providing an extruder and a starch-containing admixture having a moisture content of no greater than 30% by weight;   (b) subjecting the starch-containing admixture in the extruder to a pressure of at least 1,000 pounds per square inch at a temperature of at least 125° Celsius and which modifies at least some of the starch in the starch-containing admixture into a cold-water soluble binder;   (c) extruding starch-containing absorbent pellets from the extruder, each comprised of the water-soluble binder which forms a flowable adhesive when wetted with a room temperature water having a temperature of between 68° F. and 74° F., the flowable adhesive having a viscosity of (i) at least 200 centipoise within one second after wetting with the room temperature water, (ii) at least 300 centipoise after one second and within five seconds after wetting with the room temperature water, and (iii) at least 400 centipoise after five seconds and within 10 seconds after wetting with the room temperature water, where the viscosity of the flowable adhesive is measured with a Brookfield DV3T viscometer at a spindle rotation of 50 RPM;   (d) wetting the extruded starch-containing absorbent pellets with the room temperature water having a temperature of between 68° F. and 74° F. causing the cold-water soluble binder therein to form the flowable adhesive; and   (e) measuring the viscosity of the flowable adhesive with the Brookfield DV3T viscometer at the spindle rotation of 50 RPM, the flowable adhesive having a viscosity of (i) at least 200 centipoise within one second after wetting with the room temperature water, (ii) at least 300 centipoise after one second and within five seconds after wetting with the room temperature water, and (iii) at least 400 centipoise after five seconds and within 10 seconds after wetting with the room temperature water, the viscosity of the flowable adhesive measured with a Brookfield DV3T viscometer at a spindle rotation of 50 RPM.   
     
     
         34 . A method of making extruded granular sorbent comprising:
 (a) providing an extruder and a starch-containing admixture having a moisture content of no greater than 30% by weight;   (b) subjecting the starch-containing admixture in the extruder to a pressure of at least 1,000 pounds per square inch at a temperature of at least 125° Celsius and which modifies at least some of the starch in the starch-containing admixture into a cold-water soluble binder;   (c) extruding starch-containing absorbent pellets from the extruder, each comprised of the water-soluble binder which forms a flowable adhesive when wetted with a room temperature water having a temperature of between 68° F. and 74° F., the flowable adhesive having a viscosity of (i) at least 400 centipoise within one second after wetting with the room temperature water, (ii) at least 500 centipoise after one second and within five seconds after wetting with the room temperature water, and (iii) at least 700 centipoise after five seconds and within ten seconds after wetting with the room temperature water, where the viscosity of the flowable adhesive is measured with a Brookfield DV3T viscometer at a spindle rotation of 50 RPM;   (d) wetting the extruded starch-containing absorbent pellets with the room temperature water having a temperature of between 68° F. and 74° F. causing the cold-water soluble binder therein to form the flowable adhesive; and   (e) measuring the viscosity of the flowable adhesive with the Brookfield DV3T viscometer at the spindle rotation of 50 RPM, the flowable adhesive having a viscosity of (i) at least 400 centipoise within one second after wetting with the room temperature water, (ii) at least 500 centipoise after one second and within five seconds after wetting with the room temperature water, and (iii) at least 700 centipoise after five seconds and within ten seconds after wetting with the room temperature water, the viscosity of the flowable adhesive measured with a Brookfield DV3T viscometer at a spindle rotation of 50 RPM.   
     
     
         35 . A method of making extruded granular sorbent comprising:
 (a) providing an extruder and a starch-containing admixture having a moisture content of no greater than 30% by weight;   (b) subjecting the starch-containing admixture in the extruder to a pressure of at least 1,000 pounds per square inch at a temperature of at least 125° Celsius and which modifies at least some of the starch in the starch-containing admixture into a cold-water soluble binder;   (c) extruding starch-containing absorbent pellets from the extruder, each comprised of the cold-water soluble binder which forms a flowable adhesive when wetted with a room temperature water having a temperature of between 68° F. and 74° F., the flowable adhesive having a viscosity of (i) at least 400 centipoise within one second after wetting with the room temperature water, (ii) at least 500 centipoise after one second and within five seconds after wetting with the room temperature water, (iii) at least 700 centipoise after five seconds and within ten seconds after wetting with the room temperature water, (iv) at least 1000 centipoise after ten seconds and within twenty seconds after wetting with the room temperature water, (v) at least 1800 centipoise after twenty seconds and within twenty-five seconds after wetting with the room temperature water, (vi) at least 2500 centipoise after twenty-five seconds and within thirty seconds after wetting with the room temperature water, and (vii) at least 5000 centipoise after thirty seconds and within forty seconds after wetting with the room temperature water, where the viscosity of the flowable adhesive is measured with a Brookfield DV3T viscometer at a spindle rotation of 50 RPM;   (d) wetting the extruded starch-containing absorbent pellets with the room temperature water having a temperature of between 68° F. and 74° F. causing the cold-water soluble binder therein to form the flowable adhesive; and   (e) measuring the viscosity of the flowable adhesive with the Brookfield DV3T viscometer at the spindle rotation of 50 RPM, the flowable adhesive having a viscosity of (i) at least 400 centipoise within one second after wetting with the room temperature water, (ii) at least 500 centipoise after one second and within five seconds after wetting with the water, (iii) at least 700 centipoise after five seconds and within ten seconds after wetting with the room temperature water, (iv) at least 1000 centipoise after ten seconds and within twenty seconds after wetting with the room temperature water, (v) at least 1800 centipoise after twenty seconds and within twenty-five seconds after wetting with the room temperature water, (vi) at least 2500 centipoise after twenty-five seconds and within thirty seconds after wetting with the room temperature water, and (vii) at least 5000 centipoise after thirty seconds and within forty seconds of wetting with the room temperature water, the viscosity of the flowable adhesive measured with a Brookfield DV3T viscometer at a spindle rotation of 50 RPM.