Device and method for producing polylactic acid material

Abstract

The invention relates to a device for producing a polylactic acid material. The device comprises a pre-melting kettle, a pre-polymerization kettle, a tubular reactor and an extruder, wherein the pre-melting kettle is used for melting lactide monomers; the pre-polymerization kettle is used for pre-polymerization of lactide monomer melt; the tubular reactor is used for directly polymerizing the prepolymer; the extruder is used for removing residual lactide monomers from the obtained polymer; and the pre-melting kettle, the pre-polymerization kettle, the tubular reactor and the extruder are sequentially connected together. The invention also relates to a method for producing the polylactic acid material. The method comprises the following steps of: a) melting the lactide monomers; b) pre-polymerizing the lactide monomer melt; c) directly polymerizing the prepolymer obtained in the b) in the tubular reactor; and d) removing the residual lactide monomers from the polymer obtained in the c), and thus obtaining the polylactic acid material. The device and the method can be used for producing the polylactic acid material with high monomer conversion rate and low monomer residue.

Description

technical field

[0001] The present invention relates to a device and a method for producing polylactic acid-based materials, more particularly, to a device and method for producing polylactic acid-based materials with low monomer residues. Background technique

[0002] In recent years, with the widespread use of plastic products such as polyethylene, polypropylene, polystyrene and polyvinyl chloride, the disposal of waste after use has become one of the increasingly serious environmental problems. These wastes are usually disposed of by incineration or landfill. Incineration will produce harmful gases. Due to the high chemical stability of the above-mentioned plastic products, microbial decomposition hardly occurs after landfill treatment, but remains in a semi-permanent state.

[0003] In order to solve the above problems, researchers have vigorously developed environmentally friendly biodegradable polymers, one of which is polylactic acid. Polylactic acid can be produce...

Examples

Embodiment 1

[0062] Add 15kg of L-lactide into a 500L pre-melting kettle, pump out the air in the kettle and fill it with nitrogen, then raise the temperature to 120°C after vacuuming and nitrogen filling several times. After the L-lactide is completely melted, it is supplied to a 15L prepolymerization tank by a melt metering pump. Add 15g of stannous octoate therein so that its weight based on L-lactide is 0.1% by weight, heat up to 130°C, then start prepolymerization at 0.1Mpa, open when the L-lactide conversion rate reaches 10% Outlet valve, which feeds the contents of the prepolymerization tank into the tubular reactor. The tubular reactor used consisted of 4 sections, each 1.1 m long, with a total length of 4.4 m. The polymerization temperature is controlled at 160-210°C by means of multi-stage temperature control, and then the polymerization is started at 0.4Mpa. The total residence time of materials in the tubular reactor was 3 hours, and the conversion rate of L-lactide was 99%. ...

Embodiment 2

[0064] Add 15kg of DL-lactide into a 500L pre-melting kettle, pump out the air in the kettle and fill it with nitrogen. After several times of vacuuming and nitrogen filling, the temperature is raised to 140°C. After the DL-lactide is completely melted, it is supplied to a 25L prepolymerization tank through a melt metering pump. Add 15g stannous benzoate therein so that its weight based on DL-lactide is 0.1% by weight, be warming up to 180°C, then start prepolymerization at 0.4Mpa, when the DL-lactide conversion rate reaches 30% Open the discharge valve and feed the contents of the prepolymerization tank into the tubular reactor. The tubular reactor used consisted of 4 sections, each 1.1 m long, with a total length of 4.4 m. The polymerization temperature is controlled at 180-200°C by means of multi-stage temperature control, and then the polymerization is started at 1.0Mpa. The total residence time of materials in the tubular reactor was 0.5 hour, and the conversion rate of...

Embodiment 3

[0066]A mixture of 15 kg of L-lactide and glycolide (the weight ratio of L-lactide and glycolide is 80:20) was added into a premelting kettle with a volume of 500 L, and the air in the kettle was removed and filled with nitrogen. After evacuating and filling with nitrogen several times, the temperature was raised to 130°C. After L-lactide and glycolide are completely melted, they are supplied to a 15L prepolymerization tank by a melt metering pump. 7.5g stannous chloride is added thereto so that it is 0.05% by weight based on the total weight of L-lactide and glycolide, the temperature is raised to 140°C, and then prepolymerization is started at 0.4Mpa, when L-lactide After the overall conversion rate of glycolide and glycolide reaches 21%, the discharge valve is opened, and the contents of the prepolymerization tank are fed into the tubular reactor. The tubular reactor used consisted of 4 sections, each 1.1 m long, with a total length of 4.4 m. The polymerization temperatur...

technical field

[0001] The present invention relates to a device and a method for producing polylactic acid-based materials, more particularly, to a device and method for producing polylactic acid-based materials with low monomer residues. Background technique

[0002] In recent years, with the widespread use of plastic products such as polyethylene, polypropylene, polystyrene and polyvinyl chloride, the disposal of waste after use has become one of the increasingly serious environmental problems. These wastes are usually disposed of by incineration or landfill. Incineration will produce harmful gases. Due to the high chemical stability of the above-mentioned plastic products, microbial decomposition hardly occurs after landfill treatment, but remains in a semi-permanent state.

[0003] In order to solve the above problems, researchers have vigorously developed environmentally friendly biodegradable polymers, one of which is polylactic acid. Polylactic acid can be produce...

Examples

Embodiment 1

[0062] Add 15kg of L-lactide into a 500L pre-melting kettle, pump out the air in the kettle and fill it with nitrogen, then raise the temperature to 120°C after vacuuming and nitrogen filling several times. After the L-lactide is completely melted, it is supplied to a 15L prepolymerization tank by a melt metering pump. Add 15g of stannous octoate therein so that its weight based on L-lactide is 0.1% by weight, heat up to 130°C, then start prepolymerization at 0.1Mpa, open when the L-lactide conversion rate reaches 10% Outlet valve, which feeds the contents of the prepolymerization tank into the tubular reactor. The tubular reactor used consisted of 4 sections, each 1.1 m long, with a total length of 4.4 m. The polymerization temperature is controlled at 160-210°C by means of multi-stage temperature control, and then the polymerization is started at 0.4Mpa. The total residence time of materials in the tubular reactor was 3 hours, and the conversion rate of L-lactide was 99%. ...

Embodiment 2

[0064] Add 15kg of DL-lactide into a 500L pre-melting kettle, pump out the air in the kettle and fill it with nitrogen. After several times of vacuuming and nitrogen filling, the temperature is raised to 140°C. After the DL-lactide is completely melted, it is supplied to a 25L prepolymerization tank through a melt metering pump. Add 15g stannous benzoate therein so that its weight based on DL-lactide is 0.1% by weight, be warming up to 180°C, then start prepolymerization at 0.4Mpa, when the DL-lactide conversion rate reaches 30% Open the discharge valve and feed the contents of the prepolymerization tank into the tubular reactor. The tubular reactor used consisted of 4 sections, each 1.1 m long, with a total length of 4.4 m. The polymerization temperature is controlled at 180-200°C by means of multi-stage temperature control, and then the polymerization is started at 1.0Mpa. The total residence time of materials in the tubular reactor was 0.5 hour, and the conversion rate of...

Embodiment 3

[0066]A mixture of 15 kg of L-lactide and glycolide (the weight ratio of L-lactide and glycolide is 80:20) was added into a premelting kettle with a volume of 500 L, and the air in the kettle was removed and filled with nitrogen. After evacuating and filling with nitrogen several times, the temperature was raised to 130°C. After L-lactide and glycolide are completely melted, they are supplied to a 15L prepolymerization tank by a melt metering pump. 7.5g stannous chloride is added thereto so that it is 0.05% by weight based on the total weight of L-lactide and glycolide, the temperature is raised to 140°C, and then prepolymerization is started at 0.4Mpa, when L-lactide After the overall conversion rate of glycolide and glycolide reaches 21%, the discharge valve is opened, and the contents of the prepolymerization tank are fed into the tubular reactor. The tubular reactor used consisted of 4 sections, each 1.1 m long, with a total length of 4.4 m. The polymerization temperatur...

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