A method and device for producing chlorinated polyethylene by using microbubble reaction

Abstract

The present invention belongs to the technical field of chlorinated polyethylene production, and specifically discloses a method and device for producing chlorinated polyethylene by using a microbubble reaction. The method comprises the following steps: S1, preparing a microcapsule form auxiliary agent; S2, attaching and penetrating the microcapsule form auxiliary agent to polyethylene particles; S3, after chlorine gas passes through a microbubble generator, chlorine gas microbubbles are formed and enter the bottom of a reaction kettle, and fully contact with the polyethylene particles and a reaction auxiliary agent, and a reaction occurs simultaneously on the surface and inside of the polyethylene particles; S4, after the chlorination reaction is completed, washing, centrifuging and drying are carried out to obtain a chlorinated polyethylene product. The present invention adopts a microbubble reaction production process, reduces the chlorine gas bubble diameter, increases the mass transfer area of the chlorination reaction, makes it easier for chlorine gas to enter the inside of the polyethylene particles for reaction, improves the chlorination reaction rate and chlorination uniformity, shortens the production cycle, further improves the product quality, reduces the reaction pressure at the same time, and improves the safety of the equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of chlorinated polyethylene production, and particularly relates to a method and device for producing chlorinated polyethylene by using a microbubble reaction. Background Art

[0002] Chlorinated polyethylene is a chlorine-containing polymer obtained by the substitution reaction of polyethylene chlorination. Due to the introduction of chlorine atoms into the high-density polyethylene molecular chain, the chlorinated polyethylene product has certain characteristics such as elasticity, low-temperature toughness, and weather resistance. It can be used in resin modification for material processing, engineering plastics and other fields, and is widely used in industries such as wire and cable.

[0003] The main production methods of chlorinated polyethylene include solid-phase method, solvent method and suspension method. At present, the most widely used in industrial production is the suspension method, which uses water or hydrochloric acid as the dispersion solution and introduces chlorine from the top or bottom of the reaction kettle. The chlorination reaction extends gradually from the surface to the inside of the polyethylene particles, so the chlorination reaction is uneven throughout the polyethylene particles, the dissolution performance of the product is poor, and it is difficult to improve the quality of the product.

[0004] In order to solve the problem of uneven chlorination, raw material production enterprises mostly adopt methods such as reducing the particle size of high-density polyethylene raw materials and increasing the pore size of high-density polyethylene raw materials. However, due to limitations in catalysts and process technologies, these are difficult to achieve major breakthroughs. In order to achieve uniform chlorination, chlorinated polyethylene production enterprises try to make technological breakthroughs by continuously improving production aids, increasing the pressure and temperature of chlorination, etc. However, with the increase in pressure and temperature, more stringent requirements are put forward for production equipment, which not only increases production costs, but also poses higher requirements for production safety. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for producing chlorinated polyethylene by using a microbubble reaction, which can effectively improve the chlorination uniformity, shorten the reaction time, and improve the product quality.

[0006] To solve the above technical problem, the technical solution of the present invention is:

[0007] A method for producing chlorinated polyethylene by using a microbubble reaction, comprising the following steps:

[0008] S1. Prepare a microcapsule-shaped auxiliary agent

[0009] Mix various reaction aids with water and stir evenly. Through high-speed dispersion and shearing action, the solids and liquids in the premixed reaction aids are mixed and dispersed into tiny particles to form a microcapsule-shaped auxiliary agent suspended and dispersed in water;

[0010] S2. Attachment and penetration of the microcapsule-shaped auxiliary agent to polyethylene particles

[0011] Add the reaction medium into the reactor, start stirring, and add the raw material polyethylene and the microcapsule morphology aid into the reactor to make the microcapsule morphology aid stably suspended and dispersed in the reaction medium; when the microcapsule morphology aid encounters the polyethylene particles, it uniformly adheres to the surface of the polyethylene particles. At the same time, due to the small particle size of the microcapsule morphology aid, it also penetrates into the pores inside the polyethylene particles to ensure the uniformity of the subsequent chlorination reaction.

[0012] S3. Microbubble chlorination reaction

[0013] Chlorine gas forms chlorine microbubbles through the microbubble generator and enters the bottom of the reactor. The chlorine microbubbles are dispersed in the reactor and slowly rise, making full contact with the polyethylene particles and the reaction aid. Since the diameter of the chlorine microbubbles is extremely small, they can enter the pores of the polyethylene particles, and the reaction occurs simultaneously on the surface and inside of the polyethylene particles, greatly increasing the uniformity of the chlorination reaction.

[0014] S4. After the chlorination reaction is completed, wash, centrifuge, and dry to obtain the chlorinated polyethylene product.

[0015] Preferably, in step S1, the dispersion shear speed is 8000 - 12000 revolutions per minute.

[0016] Preferably, in step S1, the particle size of the formed microcapsule morphology aid is 0.2 - 0.4 um.

[0017] Preferably, in step S2, the pore diameter of the polyethylene particles is 0.2 - 0.6 um.

[0018] Preferably, in step S3, the diameter of the chlorine microbubbles is 0.05 - 5 um.

[0019] Preferably, the stirring of the reactor uses a flat paddle stirrer.

[0020] Preferably, during the chlorination reaction, the stirring speed of the reactor is 70 - 120 revolutions per minute.

[0021] Preferably, during the chlorination reaction, the pressure of the reactor is less than 0.3 MPa.

[0022] In step S2, the reaction medium is water or hydrochloric acid.

[0023] Preferably, in step S2, the reaction aid includes a surfactant, a suspension stabilizer, an anti-sticking agent, and an initiator.

[0024] Compared with the prior art, the present invention has at least the following beneficial effects:

[0025] (1) The present invention adopts a microbubble reaction production process, which increases the contact area between chlorine gas, polyethylene particles and reaction aids. Not only the reaction rate is improved, but also due to the microcapsule morphology aids and chlorine microbubbles can penetrate into the interior of polyethylene particles, making the reaction more uniform, effectively solving the problem that it is difficult to improve the product quality due to uneven chlorination of chlorinated polyethylene. At the same time, the microbubble reaction production process is adopted to accelerate the reaction rate, reduce the pressure of the chlorination reaction and shorten the time, which not only reduces the production cost, but also is more conducive to equipment safety and process operation safety.

[0026] (2) In the present invention, through high-speed dispersion and shearing, the reaction aids can be dispersed into the slurry in a smaller and more uniform microcapsule form, forming a stable suspension state in the slurry, having a larger contact area with polyethylene particles, and being able to partially enter the pores of polyethylene particles, penetrate into the interior and adhere, effectively increasing the reaction area, and at the same time ensuring the uniformity of the subsequent chlorination reaction.

[0027] (3) The present invention uses a microbubble generator to refine chlorine gas into bubbles, making the chlorine gas bubbles entering the reaction kettle smaller, more uniform in diameter, and able to maintain a longer existence time. The chlorine gas bubbles can not only uniformly and quickly adhere to the surface of polyethylene particles, but also more easily enter the interior of the pores of polyethylene particles to react inside, avoiding the phenomenon of relying on high pressure and high temperature to enter the interior of the pores of polyethylene particles in the traditional way, making the reaction more uniform, the pressure lower, and the reaction rate faster, greatly improving the production efficiency and product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The following drawings are only intended to illustrate and explain the present invention schematically, and do not limit the scope of the present invention. Among them:

[0029] Figure 1 is a schematic diagram of the production device of the present invention;

[0030] Figure 2 is a process flow chart of the present invention;

[0031] Figure 3 is a comparison diagram of the surface morphologies of the chlorinated polyethylene products produced in Example 1 and Comparative Example 1 of the present invention detected by SEM;

[0032] Figure 4 is a comparison diagram of the chlorine content distribution of the chlorinated polyethylene products produced in Example 1 and Comparative Example 1 of the present invention detected by SEM in cooperation with EDS;

[0033] Figure 5 is a comparison diagram of the thermal stability effects of the chlorinated polyethylene products produced in Example 1 and Comparative Example 1 of the present invention.

[0034] In the figure: 1 - premixing tank; 2 - disperser; 3 - reactor; 4 - liquid chlorine vaporizer; 5 - chlorine buffer tank; 6 - microbubble generator; 7 - water wash filter; 8 - centrifuge; 9 - dryer. Specific Embodiments

[0035] The present invention will be further described below in conjunction with the accompanying drawings and embodiments. In the following detailed description, only certain exemplary embodiments of the present invention are described by way of illustration. Without doubt, those of ordinary skill in the art can recognize that the described embodiments can be modified in various different ways without departing from the spirit and scope of the present invention. Therefore, the drawings and the description are illustrative in nature and not intended to limit the scope of protection of the claims.

[0036] Embodiment 1

[0037] Refer to Figure 1 and Figure 2 , a method for producing chlorinated polyethylene by using a microbubble reaction, comprising the following steps:

[0038] S1. Preparation of microcapsule-shaped auxiliaries

[0039] By weight, 0.01 part of surfactant, 0.02 part of suspension stabilizer, 0.01 part of initiator, and 50 parts of water are added to the premixing tank 1 for premixing and stirring, and each reaction auxiliary is preliminarily dispersed;

[0040] The premixed reaction auxiliaries are transported to the disperser 2, the stirring speed of the disperser 2 is adjusted to 10,000 revolutions per minute, and high-speed mixing is carried out for 20 minutes. Through high-speed dispersion and shearing action, the solids and liquids in the premixed reaction auxiliaries are mixed and broken into tiny particles to form microcapsule-shaped auxiliaries with a particle size of about 0.3 μm suspended and dispersed in water; the formation of the microcapsule-shaped auxiliaries provides a guarantee condition for the uniformity of the subsequent auxiliary dispersion;

[0041] S2. Attachment and penetration of microcapsule-shaped auxiliaries to polyethylene particles

[0042] 1000 parts by weight of water is added to the reactor 3 as a reaction medium. When the liquid level is higher than the stirring impeller, stirring is started, and 50 parts by weight of high-density polyethylene and the microcapsule-shaped auxiliaries formed in step 1 are added to the reactor 3, so that the microcapsule-shaped auxiliaries are stably suspended and dispersed in the reaction medium; when the microcapsule-shaped auxiliaries encounter the polyethylene particles, while uniformly adhering to the surface of the polyethylene particles, due to the small particle size of the microcapsule-shaped auxiliaries and the pore diameter D50 of the polyethylene particles being about 0.4 μm, the microcapsule-shaped auxiliaries simultaneously penetrate into the pores inside the polyethylene particles, enabling the polyethylene particles to be stably dispersed into the reaction medium and ensuring the uniformity of the subsequent chlorination reaction;

[0043] S3. Microbubble chlorination reaction

[0044] Liquid chlorine forms chlorine microbubbles with a bubble diameter of 0.05 - 5 μm after passing through a liquid chlorine vaporizer 4, a chlorine gas buffer tank 5, and a microbubble generator 6, and enters the bottom of the reaction kettle 3. The bubbles are rich and dense. After the chlorine microbubbles enter the reaction kettle 3, they disperse in the kettle and slowly rise, ensuring the opportunity to contact more polyethylene particles and avoiding the increase in the pressure of the gas phase part after the chlorine quickly rises to the gas phase part. Since the diameter of the chlorine microbubbles is extremely small, they can enter the pores of the polyethylene particles, and the reaction occurs simultaneously on the surface and inside of the polyethylene particles, greatly increasing the uniformity of the chlorination reaction. Chlorine decomposes under the action of reaction aids and temperature to generate chlorine free radicals, which then undergo substitution reactions with hydrogen atoms in polyethylene. As the reaction continues, the chlorine atoms on the polyethylene molecules gradually increase. After reaching the predetermined chlorine feeding amount (60 parts by weight), the chlorine feeding is stopped, and the chlorination reaction ends. The reaction time is 2.4 hours.

[0045] Among them, the stirring of the reaction kettle 3 uses a flat paddle stirrer. During the chlorination reaction, the stirring speed of the reaction kettle 3 is 80 revolutions per minute, avoiding excessive stirring from damaging the chlorine microbubbles and ensuring the shape of the chlorine microbubbles in the reaction kettle 3.

[0046] Since the chlorination reaction is an exothermic reaction, in order to timely remove the heat of the reaction and avoid the influence of local overheating on the product quality, the pressure of the reaction kettle 3 is controlled at 0.25 MPa. This not only controls the chlorine feeding speed to make the reaction stable and uniform, but also reduces the pressure of the reaction kettle, which is beneficial to the safety of the equipment and the process operation.

[0047] S4. After the chlorination reaction ends, the slurry is washed by a water washing filter 7, centrifuged by a centrifuge 8, and dried by a dryer 9 to obtain a chlorinated polyethylene product. After detection, the chlorine content of the product is 35.2%.

[0048] Example 2

[0049] Reference Figure 1 and Figure 2 A method for producing chlorinated polyethylene using a microbubble reaction includes the following steps:

[0050] S1. Prepare a microcapsule form aid

[0051] By weight, 0.5 part of a surfactant, 0.5 part of a suspension stabilizer, 2.5 parts of an anti-sticking agent, 0.2 part of an initiator, and 100 parts of water are added to a premixing tank 1 for premixing and stirring, and each reaction aid is preliminarily dispersed.

[0052] Transport the premixed reaction aid to the disperser 2, adjust the stirring speed of the disperser 2 to 10,000 revolutions per minute, and mix at high speed for 20 minutes. Through the high-speed dispersion and shearing action, the solids and liquids in the premixed reaction aid are mixed and broken into tiny particles to form a microcapsule-shaped aid with a particle size of about 0.3 um suspended and dispersed in water;

[0053] S2. Attachment and penetration of the microcapsule-shaped aid to polyethylene particles

[0054] Add 1000 parts by weight of 18 wt% hydrochloric acid solution to the reaction kettle 3 as the reaction medium. When the liquid level is higher than the stirring paddle, start stirring, and add 200 parts by weight of high-density polyethylene and the microcapsule-shaped aid formed in step 1 to the reaction kettle 3 to make the microcapsule-shaped aid stably suspended and dispersed in the reaction medium; when the microcapsule-shaped aid encounters polyethylene particles, while evenly attaching to the surface of the polyethylene particles, due to the small particle size of the microcapsule-shaped aid and the pore diameter D50 of the polyethylene particles being about 0.4 um, the microcapsule-shaped aid also penetrates into the pores inside the polyethylene particles, enabling the polyethylene particles to be stably dispersed in the reaction medium and ensuring the uniformity of the subsequent chlorination reaction;

[0055] S3. Microbubble chlorination reaction

[0056] Liquid chlorine forms chlorine microbubbles with a bubble diameter of 0.05 - 5 um after passing through the liquid chlorine vaporizer 4, the chlorine buffer tank 5, and the microbubble generator 6 and enters the bottom of the reaction kettle 3. The bubbles are rich and dense. After the chlorine microbubbles enter the reaction kettle 3, they are dispersed in the kettle and slowly rise, ensuring the opportunity to contact more polyethylene particles and avoiding the rapid increase in the pressure of the gas phase after the chlorine quickly rises to the gas phase part; due to the extremely small diameter of the chlorine microbubbles, they can enter the pores of the polyethylene particles, and the reaction occurs simultaneously on the surface and inside of the polyethylene particles, greatly increasing the uniformity of the chlorination reaction; chlorine decomposes under the action of the reaction aid and temperature to generate chlorine radicals, which then undergo substitution reactions with hydrogen atoms in polyethylene. As the reaction continues, the chlorine atoms on the polyethylene molecules gradually increase. After reaching the predetermined chlorine content (180 parts by weight), stop passing chlorine to end the chlorination reaction. During the reaction process, control the pressure in the reaction kettle 3 at 0.25 MPa and the reaction time at 2.5 hours;

[0057] S4. After the chlorination reaction ends, the slurry is successively washed with water by the water wash filter 7, centrifuged by the centrifuge 8, and dried by the dryer 9 to obtain a chlorinated polyethylene product. After testing, the chlorine content of the product is 34.9%.

[0058] Comparative Example 1

[0059] According to the raw material and dosage ratios of each reaction aid, polyethylene, chlorine feeding amount, and reaction medium in Example 1, conduct a control production test using the traditional process.

[0060] Add 1000 parts by weight of water into the reactor as the reaction medium. When the liquid level is higher than the stirring impeller, start stirring, and add 50 parts by weight of high-density polyethylene, 0.01 part of surfactant, 0.02 part of suspension stabilizer, and 0.01 part of initiator to obtain a suspension solution;

[0061] Pass chlorine gas into the suspension solution for chlorination reaction. The reaction temperature is 30 - 120 °C, the chlorine gas input amount is 60 parts by weight, and the reaction time is 3.2 h;

[0062] After the chlorination reaction is completed, the slurry is successively washed with water, centrifuged, and dried to obtain a chlorinated polyethylene product. After detection, the chlorine content of the product is 35.1%.

[0063] Comparative Example 2

[0064] According to the raw material and dosage ratio of each reaction assistant, polyethylene, chlorine gas input amount, and reaction medium in Example 2, a control production test is carried out using the traditional process.

[0065] Add 1000 parts by weight of 18 wt% hydrochloric acid solution into the reactor as the reaction medium. When the liquid level is higher than the stirring impeller, start stirring, and add 200 parts by weight of high-density polyethylene, 0.5 part of surfactant, 0.5 part of suspension stabilizer, 2.5 parts of anti-sticking agent, and 0.2 part of initiator to obtain a suspension solution;

[0066] Pass chlorine gas into the suspension solution for chlorination reaction. The reaction temperature is 30 - 120 °C, the chlorine gas input amount is 180 parts by weight, and the reaction time is 3.5 h;

[0067] After the chlorination reaction is completed, the slurry is successively washed with water, centrifuged, and dried to obtain a chlorinated polyethylene product. After detection, the chlorine content of the product is 35.0%.

[0068] Reference Figure 3 And Figure 4 , Sample 1# is the surface morphology and chlorine content distribution of chlorinated polyethylene particles produced by the traditional process in Comparative Example 1, and Sample 2# is the surface morphology and chlorine content distribution of chlorinated polyethylene particles produced by the process of the present invention in Example 1. From Figure 3 And Figure 4 It can be seen that the chlorine content distribution of the chlorinated polyethylene produced by the process of the present invention is more uniform.

[0069] Reference Figure 5 , Sample 1# is the thermal stability of chlorinated polyethylene produced by the traditional process in Comparative Example 1 at 200 °C, and Sample 2# is the thermal stability of chlorinated polyethylene produced by the process of the present invention in Example 1 at 200 °C. At 200 °C, the chlorinated polyethylene particles gradually turn yellow and brown with the increase of time, and the darker the color, the more decomposition occurs. FromFigure 5 It can be seen that the chlorinated polyethylene produced by the process of the present invention has better thermal stability.

[0070] The above are only illustrative specific embodiments of the present invention and are not intended to limit the scope of the present invention. Any equivalent changes and modifications made by those skilled in the art without departing from the concept and principle of the present invention, such as the ratio of various additives and raw materials, etc., shall fall within the scope of protection of the present invention.

Claims

1. A method for producing chlorinated polyethylene by using a microbubble reaction, characterized in that, It includes the following steps: S1. Prepare the microcapsule morphology aid Premix and stir evenly each reaction aid with water, and through the high-speed dispersion and shearing action, mix and break up the solids and liquids in the premixed reaction aid into tiny particles to form a microcapsule morphology aid suspended and dispersed in water; S2. Attachment and penetration of the microcapsule morphology aid to polyethylene particles Add the reaction medium to the reaction kettle, start stirring, add the raw material polyethylene and the microcapsule morphology aid to the reaction kettle, so that the microcapsule morphology aid is stably suspended and dispersed in the reaction medium, uniformly adheres to the surface of the polyethylene particles, and penetrates into the pores inside the polyethylene particles; S3. Microbubble chlorination reaction After chlorine gas passes through the microbubble generator, it forms chlorine gas microbubbles and enters the bottom of the reaction kettle, makes full contact with the polyethylene particles and the reaction aid, and reacts simultaneously on the surface and inside of the polyethylene particles; S4. After the chlorination reaction is completed, wash with water, centrifuge, and dry to obtain the chlorinated polyethylene product.

2. The method for producing chlorinated polyethylene by using a microbubble reaction as described in claim 1, characterized in that: In step S1, the dispersion and shearing speed is 8000 - 12000 revolutions per minute.

3. The method for producing chlorinated polyethylene by using microbubble reaction according to claim 2, characterized in that: In step S1, the particle size of the formed microcapsule morphology aid is 0.2 - 0.4 μm.

4. The method for producing chlorinated polyethylene by using microbubble reaction as claimed in claim 2, wherein: In step S2, the pore diameter of the polyethylene particles is 0.2 - 0.6 μm.

5. The method for producing chlorinated polyethylene by using microbubble reaction according to claim 1, characterized in that: In step S3, the diameter of the chlorine gas microbubbles is 0.05 - 5 μm.

6. The method for producing chlorinated polyethylene by using a microbubble reaction as described in claim 1, characterized in that: The stirring of the reaction kettle adopts a flat paddle stirrer.

7. The method for producing chlorinated polyethylene by using a microbubble reaction according to claim 6, characterized in that: During the chlorination reaction, the stirring speed of the reaction kettle is 70 - 120 revolutions per minute.

8. The method for producing chlorinated polyethylene by using a microbubble reaction as described in claim 1, characterized in that: During the chlorination reaction, the pressure of the reaction kettle is less than 0.3 MPa.

9. The method for producing chlorinated polyethylene by using microbubble reaction as claimed in claim 1, characterized in that: In step S2, the reaction medium is water or hydrochloric acid.

Images