Direct melt processing of resins
The present invention relates to an animal chew including a resin and a method of direct injection molding the animal chew using a modified screw. The screw may incorporate, for example, additional flights or a larger transition zone. Additionally, the particle size of the resin may be less than 2000 microns.
1. A method for molding an animal chew comprising:
introducing ingredients of a composition directly into an injection molding barrel of an injection molding machine, wherein said barrel houses a single screw comprising a modified single screw having a flight having a helix angle, said modified single screw comprising a transition zone having a first length L 1 and a feed zone having a second length L 2 , wherein L 1 >0.5*L 2 and a helix angle between about 15 and 20 degrees;
wherein said ingredients comprise:
raw starch which has not seen a prior thermal molding history including extrusion and any type of melt processing step, said raw starch having a controlled level of moisture and comprising unmodified starch recovered by extraction and which has not been physically or chemically altered, said raw starch having a particle size of 1-500 microns and wherein: (1) greater than 95% of the particles are less than 149 microns and 60% are less than 44 microns; or (2) greater than 97% of the particles are less than 250 microns and greater than 75% of the particles are less than 149 microns;
water; and
plasticizer;
blending said ingredients with heat with said modified single screw in said barrel, thereby producing said composition in said injection molding barrel;
providing a mold having at least one cavity to form the animal chew in open communication with said composition in said injection molding barrel; and
conveying said composition with said screw from said injection molding barrel into said at least one cavity of said mold and forming on exposure to one cycle of heat said composition into the animal chew.
2. The method of claim 1 wherein said modified single screw further comprises a metering zone having a third length L 3 , wherein L 3 >0.5*L 2 .
3. The method of claim 2 wherein said feed zone has a first channel depth CD 1 and said metering zone has a second channel depth CD 2 , wherein CD 1 >2.0*CD 2 .
4. The method of claim 1 wherein said composition further includes wheat gluten.
5. The method of claim 1 wherein said composition further includes a material derived from an animal source.
6. The method of claim 1 wherein said composition further includes a thermoplastic material.
7. The method of claim 1 wherein said composition further includes a rubber material.
8. The method of claim 1 wherein said composition further includes plant matter.