Method for preparing a biodegradable composition for the preparation of tableware, drink container, mulching film and package

1. A method for preparing a biodegradable composition for the preparation of table-ware, mulching film and package, the method comprising:

(1) treating one or more plant wastes selected from the group consisting of sugar cane residue, peanut shell, dry pine needle, rice husk, millet bran and soybean shell soaked in a 0.2-1.0% by weight of sulfuric acid or hydrochloric acid solution for 2-10 hours to degrease and modify and to wash, and then drying the same to let it have a water content of less than 10%; mixing the obtained plant wastes with starch, sorbitol, polypropylene, and polyethylene, and pulverizing the obtained mixture to obtain a powder with a particle size of larger than 70 mesh; mixing the obtained powder with calcium carbonate, stearic acid, stearate, coupling agent, defoamer, glycerine or epoxidized soybean oil and photosensitizer homogeneously; and

(2) blending the mixture obtained in step (1) in a double-screw extruder at a temperature of 160-180° C. to obtain the biodegradable composition which comprises 2-6% by weight of starch, 35-45% by weight of plant wastes, 20-30% by weight of calcium carbonate; 2-7% by weight of sorbitol, 7-13% by weight of polypropylene, 2-5% by weight of polyethylene, 2-6% by weight of coupling agent, 1-2% by weight of defoamer, 2-5% by weight of stearic acid, 2-6% by weight of stearate, 3-6% by weight of glycerine or epoxidized soybean oil, and 60-100 ppm photosensitizer.

2. The method according claim 1 , wherein the biodegradable composition comprises: 3-5% by weight of starch, 35-40% by weight of plant wastes, 20-30% by weight of calcium carbonate, 4-6% by weight of sorbitol, 8-11% by weight of polypropylene, 3-4% by weight of polyethylene, 3-5% by weight of coupling agent, 1-2% by weight of defoamer, 3-4% by weight of stearic acid, 3-5% by weight of stearate, 3-5% by weight of glycerine or epoxidized soybean oil, and 60-100 ppm photosensitizer.

3. The method according claim 1 , wherein the biodegradable composition comprises: 3% by weight of starch, 37% by weight of plant wastes, 25% by weight of calcium carbonate, 5% by weight of sorbitol, 9% by weight of polypropylene, 3% by weight of polyethylene, 5% by weight of coupling agent, 4% by weight of stearic acid, 4% by weight of stearate, 1% by weight of defoamer, 4% by weight of glycerine or epoxidized soybean oil and 60 ppm photosensitizer.

4. The method according claim 1 , wherein the starch is at least one selected from the groups consisting of corn starch, potato starch, ipomoea batatas starch, cassaya starch and a modified starch thereof with a grain size of larger than 70 mesh.

5. The method according claim 1 , wherein the calcium carbonate is light or heavy calcium carbonate with a grain size of larger than 70 mesh.

6. The method according claim 1 , wherein the coupling agent is silane.

7. The method according claim 1 , wherein the stearate is iron stearate, magnesium stearate or calcium stearate.

8. The method according claim 1 , wherein the stearate is iron stearate.

9. The method according claim 1 , wherein the photosensitizer is benzophenone.

10. The method according claim 1 , wherein the defoamer is emulsified silicone oil.