Polypropylene carbonate plastic slurry washing system and washing method

Abstract

The invention discloses a polypropylene carbonate plastic slurry washing system and method, the system comprises a washing kettle with a stirring function, the bottom of the kettle is sequentially connected with a first pump and a first centrifugal machine through pipelines, and the bottom of the first centrifugal machine is connected with a separation kettle with a stirring function through a pipeline; the bottom of the separation kettle with the stirring function is sequentially connected with a second pump and a second centrifugal machine through pipelines, and the side part of the second centrifugal machine is sequentially connected with a third pump and a mother liquor recovery tank through pipelines and then is connected with the washing kettle with the stirring function; the top of the washing kettle with the stirring function is connected with a gas phase condenser through a pipeline and then is connected with a mother liquor recovery tank; the top of the separation kettle with the stirring function is connected with the gas phase condenser through a pipeline; the bottom of the second centrifugal machine is connected with the pre-product tank through a pipeline; the system disclosed by the invention is simple in structure and low in cost, the method disclosed by the invention is simple to operate, high in treatment capacity, high in efficiency and high in product quality, and the ash content of the product is less than 1%.

Description

Technical Field

[0001] The invention belongs to the technical field of PPC synthesis, and in particular relates to a PPC slurry washing system and a washing method. Background Art

[0002] PPC (Poly propylene carbonate, abbreviated as PPC), scientifically known as polypropylene carbonate, also known as polymethyl ethylene carbonate, is a completely biodegradable and environmentally friendly plastic synthesized from carbon dioxide and propylene oxide.

[0003] Carbon dioxide is a known greenhouse gas that accounts for more than half of the greenhouse effect. The need to reduce carbon dioxide emissions has been recognized by most countries in the world.

[0004] It is generally believed that CO 2 is an inert and relatively unreactive compound, but under relatively mild conditions, CO 2 Copolymerization with propylene oxide can be carried out using organometallic compounds as catalysts to produce polycarbonates. The products of the polymerization of carbon dioxide and epoxides, both monomers and polymers, have important industrial applications. Polycarbonates have excellent properties, including light weight, good durability, good electrical insulation and degradability; in addition, they are easy to process and dye. Therefore, these materials can be widely used in the fields of electronics, optics, media, glass and plastics, automotive industry, healthcare industry, and many other consumer products.

[0005] Existing PPC plastics are synthesized by placing carbon dioxide and propylene oxide in a synthesis reactor and reacting directly under the action of a catalyst. However, the catalyst and by-products in the synthesized product are not completely removed, and the heavy metal content is high, which affects the product performance. At present, the known domestic technologies use organic solvent washing and alcohol washing. Organic solvent washing has high cost, difficult recycling, high risk factor and great difficulty. The traditional washing process of alcohols is imperfect, difficult to operate and poor in effect. Summary of the invention

[0006] The purpose of the invention is to overcome the deficiencies of the prior art and provide a polypropylene carbonate plastic slurry washing system which can avoid the problem of solvent residue and improve product quality.

[0007] The second object of the present invention is to provide a method for washing polypropylene carbonate plastic slurry at a low cost and with high product quality.

[0008] The technical solution of the present invention is summarized as follows:

[0009] The polypropylene carbonate plastic slurry washing system comprises a washing kettle 1 with stirring, wherein the bottom of the washing kettle 1 with stirring is connected to a first pump 2 and a first centrifuge 3 in sequence through a pipeline, and the bottom of the first centrifuge is connected to a separation kettle 6 with stirring through a pipeline; the bottom of the separation kettle 6 with stirring is connected to a second pump 7 and a second centrifuge 9 in sequence through a pipeline, and the side of the second centrifuge is connected to a third pump 8 and a mother liquid recovery tank 5 in sequence through a pipeline, and then connected to the washing kettle 1 with stirring; the top of the washing kettle 1 with stirring is connected to a gas phase condenser 11 through a pipeline. After the connection, it is connected to the mother liquor recovery tank 5; the top of the separation kettle 6 with stirring is connected to the gas phase condenser 11 through a pipeline; the side of the first centrifuge 3 is connected to the fourth pump 4 through a pipeline and then leads to the distillation system; the bottom of the second centrifuge 9 is connected to the pre-product tank 10 through a pipeline; the top of the mother liquor recovery tank 5 is provided with a first washing liquid addition pipe 12; the top of the separation kettle 6 with stirring is provided with a second washing liquid addition pipe 13; the top of the washing kettle 1 is provided with a PPC plastic slurry addition pipe 14, and the gas phase condenser 11 is connected to the mother liquor recovery tank 5 through a pipeline.

[0010] A method for washing polypropylene carbonate plastic slurry comprises the following steps:

[0011] 1) Using the above-mentioned polypropylene carbonate plastic slurry washing system;

[0012] 2) adding the washing liquid into the mother liquid recovery tank 5 through the first washing liquid adding pipe 12;

[0013] 3) At the same time, the PPC plastic slurry from the PPC plastic slurry adding pipe 14 and the washing liquid from the mother liquid recovery tank 5 are added to the washing kettle 1 with stirring in a mass ratio of 1:0.8-2; the stirring is carried out at a speed of 30-60rpm and stirred for 2-5h; the stirred material is passed through the first pump 2 into the first centrifuge 3 for centrifugation to obtain the first mother liquid and the first material respectively, and the first mother liquid is passed through the fourth pump 4 to the distillation system for recovery;

[0014] 4) introducing the washing liquid from the second washing liquid adding pipe 13 into the separation kettle 6 with stirring, and then introducing the first material; the mass ratio of the first material to the washing liquid is 1:0.8-3; stirring at a speed of 30-60 rpm for 3-6 hours to obtain the second material;

[0015] 5) The second material is passed through the second pump 7 into the second centrifuge 9, and centrifuged to obtain a second mother liquor and a pre-product, respectively, and the pre-product is passed into the pre-product tank 10; the second mother liquor is passed into the mother liquor recovery tank 5 through the third pump 8;

[0016] 6) The gas phase of the washing liquid produced by the washing kettle 1 with stirring and the separation kettle 6 with stirring is condensed by the gas phase condenser 11 and then introduced into the mother liquid recovery tank 5;

[0017] The PPC is the abbreviation of polypropylene carbonate.

[0018] The washing liquid is preferably ethanol or methanol.

[0019] Advantages of the present invention:

[0020] The system structure of the present invention is simple, and the equipment cost is low. The method of the present invention is simple to operate, has large processing capacity, high efficiency and high utilization rate. The product quality is high, and the ash content of the product is less than 1%. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The figure is a schematic diagram of the structure of the polypropylene carbonate plastic slurry washing system of the present invention. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with specific embodiments and drawings.

[0023] In various embodiments, PPC is the abbreviation of polypropylene carbonate.

[0024] Polypropylene carbonate plastic slurry washing system (see Figure 1 ), comprising a washing tank 1 with stirring, wherein the bottom of the washing tank 1 with stirring is connected to a first pump 2 and a first centrifuge 3 in sequence through a pipeline, and the bottom of the first centrifuge is connected to a separation tank 6 with stirring through a pipeline; the bottom of the separation tank 6 with stirring is connected to a second pump 7 and a second centrifuge 9 in sequence through a pipeline, and the side of the second centrifuge is connected to a third pump 8 and a mother liquor recovery tank 5 in sequence through a pipeline, and then connected to the washing tank 1 with stirring; the top of the washing tank 1 with stirring is connected to a gas phase condenser 11 through a pipeline, and then to The mother liquor recovery tank 5 is connected; the top of the separation kettle 6 with stirring is connected to the gas phase condenser 11 through a pipeline; the side of the first centrifuge 3 is connected to the fourth pump 4 through a pipeline and then leads to the distillation system; the bottom of the second centrifuge 9 is connected to the pre-product tank 10 through a pipeline; the top of the mother liquor recovery tank 5 is provided with a first washing liquid addition pipe 12; the top of the separation kettle 6 with stirring is provided with a second washing liquid addition pipe 13; the top of the washing kettle 1 is provided with a PPC plastic slurry addition pipe 14, and the gas phase condenser 11 is connected to the mother liquor recovery tank 5 through a pipeline.

[0025] Example 1

[0026] A method for washing polypropylene carbonate plastic slurry comprises the following steps:

[0027] 1) Using the above-mentioned polypropylene carbonate plastic slurry washing system;

[0028] 2) adding ethanol into the mother liquor recovery tank 5 through the first washing liquid adding pipe 12;

[0029] 3) At the same time, the PPC plastic slurry from the PPC plastic slurry adding pipe 14 and the washing liquid ethanol from the mother liquid recovery tank 5 are added to the washing kettle 1 with stirring in a mass ratio of 1:1; the stirring is carried out at a speed of 45 rpm for 3 hours; the stirred material is passed through the first pump 2 into the first centrifuge 3 for centrifugation to obtain the first mother liquid and the first material respectively, and the first mother liquid is passed through the fourth pump 4 to the distillation system for recovery;

[0030] 4) introducing ethanol from the second washing liquid adding pipe 13 into the separation kettle 6 with stirring, and then introducing the first material; the mass ratio of the first material to the ethanol is 1:1; stirring at a speed of 45 rpm for 4 hours to obtain the second material;

[0031] 5) The second material is introduced into the second centrifuge 9 through the second pump 7, and centrifuged to obtain the second mother liquor and the pre-product respectively, and the pre-product is introduced into the pre-product tank 10 (the ash content is 0.71%); the second mother liquor is introduced into the mother liquor recovery tank 5 through the third pump 8; 6) The gas phase of the washing liquid ethanol produced by the stirring washing kettle 1 and the stirring separation kettle 6 is condensed through the gas phase condenser 11 and then introduced into the mother liquor recovery tank 5.

[0032] Example 2

[0033] A method for washing polypropylene carbonate plastic slurry comprises the following steps:

[0034] 1) Using the above-mentioned polypropylene carbonate plastic slurry washing system;

[0035] 2) adding methanol into the mother liquor recovery tank 5 through the first washing liquid adding pipe 12;

[0036] 3) At the same time, the PPC plastic slurry from the PPC plastic slurry adding pipe 14 and the washing liquid methanol from the mother liquid recovery tank 5 are added to the washing kettle 1 with stirring at a mass ratio of 1:0.8; the stirring is carried out at a speed of 30 rpm for 5 hours; the stirred material is passed through the first pump 2 into the first centrifuge 3 for centrifugation to obtain the first mother liquid and the first material respectively, and the first mother liquid is passed through the fourth pump 4 to the distillation system for recovery;

[0037] 4) introducing washing liquid methanol from the second washing liquid adding pipe 13 into the separation kettle 6 with stirring, and then introducing the first material; the mass ratio of the first material to the washing liquid methanol is 1:0.8; stirring at a speed of 30 rpm for 6 hours to obtain the second material;

[0038] 5) The second material is introduced into the second centrifuge 9 through the second pump 7, and centrifuged to obtain a second mother liquor and a pre-product respectively, and the pre-product is introduced into the pre-product tank 10 (the ash content is 0.65%); the second mother liquor is introduced into the mother liquor recovery tank 5 through the third pump 8;

[0039] 6) The gas phase of the washing liquid methanol produced by the stirring washing kettle 1 and the stirring separation kettle 6 is condensed by the gas phase condenser 11 and then introduced into the mother liquid recovery tank 5.

[0040] Example 3

[0041] A method for washing polypropylene carbonate plastic slurry comprises the following steps:

[0042] 1) Using the above-mentioned polypropylene carbonate plastic slurry washing system;

[0043] 2) adding ethanol into the mother liquor recovery tank 5 through the first washing liquid adding pipe 12;

[0044] 3) At the same time, the PPC plastic slurry from the PPC plastic slurry adding pipe 14 and the washing liquid ethanol from the mother liquid recovery tank 5 are added to the washing kettle 1 with stirring in a mass ratio of 1:2; the stirring is carried out at a speed of 60 rpm for 2 hours; the stirred material is passed through the first pump 2 into the first centrifuge 3 for centrifugation to obtain the first mother liquid and the first material respectively, and the first mother liquid is passed through the fourth pump 4 to the distillation system for recovery;

[0045] 4) introducing washing liquid ethanol from the second washing liquid adding pipe 13 into the separation kettle 6 with stirring, and then introducing the first material; the mass ratio of the first material to the washing liquid ethanol is 1:3; stirring at a speed of 60 rpm for 3 hours to obtain the second material;

[0046] 5) The second material is introduced into the second centrifuge 9 through the second pump 7, and centrifuged to obtain the second mother liquor and the pre-product respectively, and the pre-product is introduced into the pre-product tank 10 (the ash content is 0.78%); the second mother liquor is introduced into the mother liquor recovery tank 5 through the third pump 8; 6) The gas phase of the washing liquid ethanol produced by the stirring washing kettle 1 and the stirring separation kettle 6 is condensed through the gas phase condenser 11 and then introduced into the mother liquor recovery tank 5.

Claims

1. A polypropylene carbonate plastic slurry washing system, comprising a washing kettle (1) with stirring, Its characteristics are The bottom of the stirring washing kettle (1) is connected to the first pump (2) and the first centrifuge (3) in sequence through a pipeline, and the bottom of the first centrifuge is connected to the stirring separation kettle (6) through a pipeline; the bottom of the stirring separation kettle (6) is connected to the second pump (7) and the second centrifuge (9) in sequence through a pipeline, and the side of the second centrifuge is connected to the third pump (8) and the mother liquid recovery tank (5) in sequence through a pipeline, and then connected to the stirring washing kettle (1); the top of the stirring washing kettle (1) is connected to the gas phase condenser (11) through a pipeline, and then connected to the mother liquid recovery tank (5). The top of the separation kettle (6) with stirring is connected to the gas phase condenser (11) through a pipeline; the side of the first centrifuge (3) is connected to the fourth pump (4) through a pipeline and then leads to the distillation system; the bottom of the second centrifuge (9) is connected to the pre-product tank (10) through a pipeline; the top of the mother liquid recovery tank (5) is provided with a first washing liquid addition pipe (12); the top of the separation kettle (6) with stirring is provided with a second washing liquid addition pipe (13); the top of the washing kettle (1) is provided with a PPC plastic slurry addition pipe (14), and the gas phase condenser (11) is connected to the mother liquid recovery tank (5) through a pipeline.

2. Method for washing polypropylene carbonate plastic slurry, Its characteristics are The steps include: 1) Using the polypropylene carbonate plastic slurry washing system of claim 1; 2) adding the washing liquid into the mother liquid recovery tank (5) through the first washing liquid adding pipe (12); 3) simultaneously adding the PPC plastic slurry from the PPC plastic slurry adding pipe (14) and the washing liquid from the mother liquid recovery tank (5) into a washing kettle (1) with stirring at a mass ratio of 1:0.8-2; stirring at a speed of 30-60 rpm for 2-5 hours; passing the stirred material into a first centrifuge (3) through a first pump (2) for centrifugation to obtain a first mother liquid and a first material respectively; the first mother liquid is passed to a distillation system for recovery through a fourth pump (4); 4) introducing the washing liquid from the second washing liquid adding pipe (13) into the separation kettle (6) with stirring, and then introducing the first material; the mass ratio of the first material to the washing liquid is 1:0.8-3; stirring at a speed of 30-60 rpm for 3-6 hours to obtain the second material; 5) passing the second material into a second centrifuge (9) through a second pump (7) and centrifuging to obtain a second mother liquor and a pre-product, respectively, and passing the pre-product into a pre-product tank (10); passing the second mother liquor into a mother liquor recovery tank (5) through a third pump (8); 6) The gas phase of the washing liquid produced by the washing kettle with stirring (1) and the separation kettle with stirring (6) is condensed by the gas phase condenser (11) and then introduced into the mother liquid recovery tank (5); The PPC is the abbreviation of polypropylene carbonate.

3. The washing method according to claim 2, Its characteristics are The washing liquid is ethanol or methanol.

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