Process for preparing polypropylene particles by using recyclable coffee grounds plant fibers

1. A process for preparing polypropylene particles by using recyclable coffee grounds plant fibers, comprising the following preparation steps:

1) preparing raw materials comprising of polypropylene and coffee grounds;

2) processing the raw materials;

3) mixing the raw materials processed in step 2 to obtain a mixture; and

4) performing extrusion and granulation on the mixture to obtain the polypropylene particles;

wherein the raw materials in step 1 comprise 35-40 parts by mass of coffee grounds, 60-80 parts by mass of polypropylene resin, 2-5 parts by mass of a compatibilizer, 4-8 parts by mass of a toughening agent, 1-3 parts by mass of a diffusing agent, 1-3 parts by mass of maleic anhydride, 0.7-1.6 parts by mass of an anti-UV agent, 3-6 parts by mass of an antioxidant, 1-2 parts by mass of a white oil, and 0.1-0.5 part by mass of a lubricating agent.

2. The process according to claim 1 , wherein step 2 comprises the following steps:

2.1) preparing the coffee grounds for cleaning and drying;

2.2) pulverizing and grinding the coffee grounds by using a pulverizer and a grinder to obtain coffee grounds powder;

2.3) screening the coffee grounds powder by using a 150-mesh screen; and

2.4) weighing out the coffee grounds powder screened from step 2.3.

3. The process according to claim 2 , wherein in step 2.1, the coffee grounds are washed and cleaned, baked at a high temperature to remove grease and be sterilized, and dried at 180-220° C. for 30-40 minutes to obtain semi-carbonized coffee grounds.

4. The process according to claim 2 , wherein in step 2.2, the coffee grounds are first pulverized by using the pulverizer, and then ground by using the grinder; and in step 2.3, the 150-mesh screen is used for screening, and the coffee grounds powder with a uniform size is collected.

5. The process according to claim 1 , wherein

in step 2, the coffee grounds are processed into coffee grounds powder; and

step 3 comprises the following steps:

3.1) adding the coffee grounds powder and the polypropylene resin into a mixer for a primary mixing, performing a resin modification, and intermittently adding the compatibilizer;

3.2) adding a remaining of the raw materials into the mixer for a secondary mixing to obtain the mixture, wherein the remaining of the raw materials comprises the toughening agent, the diffusing agent, the maleic anhydride, the anti-UV agent, the antioxidant, the white oil, and the lubricating agent; and

3.3) collecting the mixture and guiding the mixture into a double-screw extruder.

6. The process according to claim 5 , wherein in step 3.1, during the primary mixing, a mixing temperature is set at 40-50° C., a rotating speed is 260-300 r/min, the primary mixing is performed for 20-25 min, and the polypropylene resin is modified with the coffee grounds powder.

7. The process according to claim 5 , wherein in step 3.1, a funnel is used, an electromagnetic valve is disposed on the funnel, and the funnel is opened intermittently so that the compatibilizer is intermittently added into the mixer, and mixed with the coffee grounds powder and the polypropylene resin to facilitate the resin modification.

8. The process according to claim 5 , wherein in step 3.2, during the secondary mixing, a mixing temperature is set at 60-70° C., a rotating speed is 360-500 r/min, and the secondary mixing is performed for 10-20 min.

9. The process according to claim 1 , wherein step 4 comprises:

extruding the mixture using a double-screw extruder to obtain a strip material, wherein the strip material is extruded under the following conditions: a temperature of 170-200° C., a rotating speed of 260-300 r/min, and a main feeding frequency of 7-9 Hz,

after cooling the strip material with cold water, pelletizing the cooled strip material by using an extrusion pelletizer to prepare the polypropylene particles, wherein a rotating speed of the extruder pelletizer is 100-130 Hz/min.