Method for preparing polyethylene wax by using waste polyethylene plastic

Abstract

The present invention relates to a method for preparing polyethylene wax by using waste polyethylene plastic. The method comprises: sequentially adding 100 g of waste polyethylene plastic, 15 mL of a solvent and 0.3 g of a catalyst to an autoclave, heating to a reaction temperature while stirring under the protection of nitrogen gas, cracking for a certain time, cooling to a room temperature, discharging the material, filtering, drying, and recovering the catalyst and the solvent to obtain the polyethylene wax, wherein the solvent is the petroleum refining byproduct heavy aromatic oil, the catalyst is Al-MCM-48, the reaction temperature is usually the temperature from the raw material melting point to 420 DEG C, and the cracking time is 1-5 h. According to the present invention, the heat transfer is quick and uniform, the cracking temperature is low, the time is short, the raw material conversion rate is high, the occurrence of the phenomena such as raw material winding aggregation and excessive cracking and carbonization coking caused by local overheating can be effectively prevented, and the product has characteristics of narrow molecular weight distribution, shallow color, high drop melting point, high hardness, low viscosity and the like.

Description

technical field

[0001] The invention relates to a synthesis method of polymer wax, in particular to a method for preparing polyethylene wax from waste polyethylene plastics. Background technique

[0002] As a low molecular weight polyethylene homopolymer or copolymer, polyethylene wax has unique properties such as non-toxic, non-corrosive, good lubricity, cold resistance, heat resistance, wear resistance and chemical resistance, and is widely used in the chemical industry. For example, it is used as a pigment dispersant in the processing of masterbatches, as an internal and external lubricant and composite stabilizer in the processing of PVC and modified engineering plastics, as a lubricant in cable insulation materials, and as a lubricant in rubber processing. As an auxiliary agent, it is used as a high-quality glazing agent in high-grade paper and leather finishing, as a dispersant in the production of various hot-melt adhesives, thermosetting powder coatings, road marking...

Examples

Embodiment 1

[0013] Example 1: Take 100 g of waste polyethylene agricultural film (cleaned and shredded) and put it into a high-pressure reactor, add 0.3 g of Al-MCM-48 catalyst and 15 mL of heavy aromatic oil, seal the reactor, and purge with nitrogen for about 10 The air in the reaction kettle was removed by replacement for min, the stirring device was turned on, the temperature was raised to 380 °C, the cracking was carried out for 2.5 h, the material was cooled to room temperature and discharged, filtered and dried, and the catalyst and solvent were recovered to obtain polyethylene wax.

[0014] The polyethylene wax prepared in Example 1 is a pale yellow wax with a molecular weight of 2725.2, a drop melting point of 106.8°C, a yield of nearly 100%, no cracking gas, no raw material entanglement, and a solvent recovery rate of 97.8%.

Embodiment 2

[0015] Embodiment 2: No solvent is added, the method is the same as that of Embodiment 1, and polyethylene wax is prepared.

[0016] The polyethylene wax obtained in Example 2 is a light yellow waxy substance with a molecular weight of 1858.5-2395.5 (relatively dispersed), a drop melting point of 103.5°C, and a yield of 94.3%. There is cracking gas and entanglement of raw materials.

Embodiment 3

[0017] Embodiment 3: no catalyst is added, the method is the same as that of embodiment 1, and polyethylene wax is prepared.

[0018] The polyethylene wax prepared in Example 3 is a light yellow block with a molecular weight of 1728-2281.5 (relatively dispersed), a drop melting point of 102.4 °C, and a yield of 84.2%. A small amount of cracking gas is produced, and there is no entanglement of raw materials. The recovery rate is 98.2%.

[0019] Comparing the effects of Examples 1, 2 and 3, it can be seen that with heavy aromatic oil as solvent, Al-MCM-48 as catalyst, polyethylene wax is prepared from waste polyethylene plastics, the cracking temperature is low, the time is short, and the product molecular weight distribution is relatively Concentration, qualified quality, and can effectively solve the problems of uneven heat transfer, low efficiency, excessive cracking and carbonization and coking caused by excessive local temperature, low product yield, entanglement of raw mat...

technical field

[0001] The invention relates to a synthesis method of polymer wax, in particular to a method for preparing polyethylene wax from waste polyethylene plastics. Background technique

[0002] As a low molecular weight polyethylene homopolymer or copolymer, polyethylene wax has unique properties such as non-toxic, non-corrosive, good lubricity, cold resistance, heat resistance, wear resistance and chemical resistance, and is widely used in the chemical industry. For example, it is used as a pigment dispersant in the processing of masterbatches, as an internal and external lubricant and composite stabilizer in the processing of PVC and modified engineering plastics, as a lubricant in cable insulation materials, and as a lubricant in rubber processing. As an auxiliary agent, it is used as a high-quality glazing agent in high-grade paper and leather finishing, as a dispersant in the production of various hot-melt adhesives, thermosetting powder coatings, road marking...

Examples

Embodiment 1

[0013] Example 1: Take 100 g of waste polyethylene agricultural film (cleaned and shredded) and put it into a high-pressure reactor, add 0.3 g of Al-MCM-48 catalyst and 15 mL of heavy aromatic oil, seal the reactor, and purge with nitrogen for about 10 The air in the reaction kettle was removed by replacement for min, the stirring device was turned on, the temperature was raised to 380 °C, the cracking was carried out for 2.5 h, the material was cooled to room temperature and discharged, filtered and dried, and the catalyst and solvent were recovered to obtain polyethylene wax.

[0014] The polyethylene wax prepared in Example 1 is a pale yellow wax with a molecular weight of 2725.2, a drop melting point of 106.8°C, a yield of nearly 100%, no cracking gas, no raw material entanglement, and a solvent recovery rate of 97.8%.

Embodiment 2

[0015] Embodiment 2: No solvent is added, the method is the same as that of Embodiment 1, and polyethylene wax is prepared.

[0016] The polyethylene wax obtained in Example 2 is a light yellow waxy substance with a molecular weight of 1858.5-2395.5 (relatively dispersed), a drop melting point of 103.5°C, and a yield of 94.3%. There is cracking gas and entanglement of raw materials.

Embodiment 3

[0017] Embodiment 3: no catalyst is added, the method is the same as that of embodiment 1, and polyethylene wax is prepared.

[0018] The polyethylene wax prepared in Example 3 is a light yellow block with a molecular weight of 1728-2281.5 (relatively dispersed), a drop melting point of 102.4 °C, and a yield of 84.2%. A small amount of cracking gas is produced, and there is no entanglement of raw materials. The recovery rate is 98.2%.

[0019] Comparing the effects of Examples 1, 2 and 3, it can be seen that with heavy aromatic oil as solvent, Al-MCM-48 as catalyst, polyethylene wax is prepared from waste polyethylene plastics, the cracking temperature is low, the time is short, and the product molecular weight distribution is relatively Concentration, qualified quality, and can effectively solve the problems of uneven heat transfer, low efficiency, excessive cracking and carbonization and coking caused by excessive local temperature, low product yield, entanglement of raw mat...