Method and device for producing chlorinated polyethylene by using microbubble reaction

Abstract

The invention belongs to the technical field of chlorinated polyethylene production, and particularly discloses a method and device for producing chlorinated polyethylene through a microbubble reaction. The method comprises the following steps: S1, preparing a microcapsule form additive; s2, adhering and permeating the microcapsule form additive and the polyethylene particles; s3, chlorine gas forms chlorine gas micro-bubbles after passing through a micro-bubble generator, the chlorine gas micro-bubbles enter the bottom of the reaction kettle and are in full contact with the polyethylene particles and the reaction auxiliaries, and the surfaces and the interiors of the polyethylene particles react at the same time; s4, after the chlorination reaction is finished, washing, centrifuging and drying to obtain a chlorinated polyethylene product. By adopting a microbubble reaction production process, the diameter of chlorine gas bubbles is reduced, the mass transfer area of chlorination reaction is increased, chlorine gas is easier to enter polyethylene particles for reaction, the chlorination reaction rate and the chlorination uniformity are improved, the production period is shortened, the product quality is further improved, the reaction pressure is reduced, and the production cost is reduced. And the safety of the equipment is improved.

Description

Technical Field

[0001] The invention relates to the technical field of chlorinated polyethylene production, and in particular to a method and a device for producing chlorinated polyethylene by utilizing 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, chlorinated polyethylene products have certain elasticity, low-temperature toughness and weather resistance. They can be used in the fields of resin modification and engineering plastics in material processing, and are widely used in industries such as wires and cables.

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

[0004] In order to solve the problem of uneven chlorination, raw material manufacturers often use 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 the limitations of catalysts and process technology, it is difficult to make major breakthroughs. In order to achieve uniform chlorination, chlorinated polyethylene manufacturers have tried to make technological breakthroughs by continuously improving production additives and increasing chlorination pressure and temperature. However, with the increase in pressure and temperature, more stringent requirements are placed on production equipment, which not only increases production costs, but also places higher requirements on 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 microbubble reaction, which can effectively improve the chlorination uniformity, shorten the reaction time and improve the product quality.

[0006] In order to solve the above technical problems, the technical solution of the present invention is: A method for producing chlorinated polyethylene by microbubble reaction comprises the following steps: S1. Preparation of microcapsule morphology additives Each reaction aid is premixed with water and stirred evenly, and the solid and liquid in the premixed reaction aid are mixed and broken into tiny particles by high-speed dispersing and shearing action to form a microcapsule-shaped aid suspended and dispersed in water; S2, microcapsule morphology additives and polyethylene particles adhesion and penetration Add the reaction medium into the reactor, start stirring, add the raw polyethylene and microcapsule morphology additive into the reactor, and stably suspend and disperse the microcapsule morphology additive in the reaction medium; when the microcapsule morphology additive encounters the polyethylene particles, it evenly adheres to the surface of the polyethylene particles, and at the same time, due to the small particle size of the microcapsule morphology additive, it penetrates into the pores of the polyethylene particles, thereby ensuring the uniformity of the subsequent chlorination reaction; S3, microbubble chlorination reaction After passing through the microbubble generator, chlorine gas forms chlorine gas microbubbles and enters the bottom of the reactor. The chlorine gas microbubbles are dispersed in the reactor and slowly rise, fully contacting with the polyethylene particles and reaction aids. Since the diameter of the chlorine gas microbubbles is extremely small, they can enter the pores of the polyethylene particles and react simultaneously on the surface and inside of the polyethylene particles, greatly increasing the uniformity of the chlorination reaction. S4. After the chlorination reaction is completed, the chlorinated polyethylene product is obtained by washing, centrifugation and drying.

[0007] Preferably, in step S1, the dispersion shearing rotation speed is 8000 to 12000 rpm.

[0008] Preferably, in step S1, the particle size of the microcapsule morphology aid formed is 0.2-0.4 um.

[0009] Preferably, in step S2, the pore size of the polyethylene particles is 0.2-0.6 um.

[0010] Preferably, in step S3, the diameter of the chlorine gas microbubbles is 0.05-5 um.

[0011] Preferably, the reactor is stirred using a flat-paddle stirrer.

[0012] Preferably, during the chlorination reaction, the stirring speed of the reactor is 70 to 120 rpm.

[0013] Preferably, during the chlorination reaction, the pressure of the reactor is less than 0.3 MPa.

[0014] In step S2, the reaction medium is water or hydrochloric acid.

[0015] Preferably, in step S2, the reaction aids include surfactants, suspension stabilizers, anti-sticking agents and initiators.

[0016] Compared with the prior art, the present invention has at least the following beneficial effects: (1) The present invention adopts a microbubble reaction production process to increase the contact area between chlorine gas, polyethylene particles and reaction aids, which not only improves the reaction speed, but also makes the reaction more uniform because the microcapsule morphology aid and chlorine gas microbubbles can penetrate into the polyethylene particles, effectively solving the problem of uneven chlorination of chlorinated polyethylene causing difficulty in improving product quality. 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 is also more conducive to equipment safety and process operation safety.

[0017] (2) The present invention uses high-speed dispersive shearing to enable the reaction aid to be dispersed into the slurry in the form of smaller and more uniform microcapsules, forming a stable suspension in the slurry, having a larger contact area with the polyethylene particles, and being able to partially enter the pores of the polyethylene particles and adhere deeply to the inside, thereby effectively increasing the reaction area and ensuring the uniformity of the subsequent chlorination reaction.

[0018] (3) The present invention uses a microbubble generator to refine the chlorine bubbles, so that the diameter of the chlorine bubbles entering the reactor is smaller and more uniform, and can be maintained for a longer time, so that the chlorine bubbles can not only adhere to the surface of the polyethylene particles evenly and quickly, but also more easily enter the pores of the polyethylene particles and react inside, avoiding the traditional phenomenon of relying on high pressure and high temperature to enter the pores of the polyethylene particles, making the reaction more uniform, the pressure lower, the reaction speed faster, and greatly improving the production efficiency and product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The following drawings are intended only to illustrate and explain the present invention, and are not intended to limit the scope of the present invention. Figure 1 It is a schematic diagram of the production device of the present invention; Figure 2 It is a process flow chart of the present invention; Figure 3 It is a comparison diagram of the surface morphology of the chlorinated polyethylene products produced by Example 1 of the present invention and Comparative Example 1 detected by SEM; Figure 4 This is a comparison diagram of the chlorine content distribution of the chlorinated polyethylene products produced in Example 1 of the present invention and Comparative Example 1 detected by SEM and EDS; Figure 5 It is a comparison chart of the thermal stability effects of the chlorinated polyethylene products produced by Example 1 of the present invention and Comparative Example 1.

[0020] In the figure: 1-premixing tank; 2-disperser; 3-reactor; 4-liquid chlorine vaporizer; 5-chlorine buffer tank; 6-microbubble generator; 7-water washing filter; 8-centrifuge; 9-dryer. DETAILED DESCRIPTION

[0021] The present invention is further described below in conjunction with the accompanying drawings and examples. In the following detailed description, certain exemplary embodiments of the present invention are described only by way of illustration. Needless to say, those of ordinary skill in the art will recognize that the described embodiments may be modified in various ways without departing from the spirit and scope of the present invention. Therefore, the drawings and description are illustrative in nature and are not intended to limit the scope of protection of the claims.

[0022] Example 1 refer to Figure 1 and Figure 2 A method for producing chlorinated polyethylene using microbubble reaction comprises the following steps: S1. Preparation of microcapsule morphology additives By weight, 0.01 parts of surfactant, 0.02 parts of suspension stabilizer, 0.01 parts of initiator, and 50 parts of water were added into premixing tank 1 for premixing and stirring, and each reaction aid was preliminarily dispersed; The premixed reaction aid is conveyed to the disperser 2, and the stirring speed of the disperser 2 is adjusted to 10,000 rpm. The mixture is mixed at high speed for 20 minutes. The solid and liquid in the premixed reaction aid are mixed and broken into tiny particles by high-speed dispersion and shearing action, forming a microcapsule-shaped aid with a particle size of about 0.3 um suspended in water. The formation of the microcapsule-shaped aid provides a guarantee for the uniformity of subsequent aid dispersion. S2, microcapsule morphology additives and polyethylene particles adhesion and penetration 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 blade, stirring is started. 50 parts by weight of high-density polyethylene and the microcapsule morphology aid formed in step 1 are added to the reactor 3, so that the microcapsule morphology aid is stably suspended and dispersed in the reaction medium. When the microcapsule morphology aid encounters polyethylene particles, it is uniformly attached to the surface of the polyethylene particles. Since the particle size of the microcapsule morphology aid is small and the pore size D50 of the polyethylene particles is about 0.4 um, the microcapsule morphology aid simultaneously penetrates into the pores of the polyethylene particles, so that the polyethylene particles can be stably dispersed in the reaction medium, thereby ensuring the uniformity of the subsequent chlorination reaction. S3, microbubble chlorination reaction After passing through the liquid chlorine vaporizer 4, the chlorine buffer tank 5, and the microbubble generator 6, the liquid chlorine forms chlorine microbubbles with a bubble diameter of 0.05 to 5 μm and enters the bottom of the reactor 3. The bubbles are abundant and dense. After entering the reactor 3, the chlorine microbubbles are dispersed in the reactor and rise slowly, ensuring the opportunity to contact with more polyethylene particles and avoiding the increase of the gas phase pressure after the chlorine rises quickly to the gas phase. Since the diameter of the chlorine microbubbles is extremely small, they can enter the pores of the polyethylene particles and react simultaneously on the surface and inside of the polyethylene particles, greatly increasing the uniformity of the chlorination reaction. Under the action of the reaction aid and temperature, the chlorine decomposes to generate chlorine free radicals, which then undergo a substitution reaction with the hydrogen atoms in the polyethylene. As the reaction continues, the chlorine atoms on the polyethylene molecules gradually increase. After reaching the predetermined chlorine flow amount (60 parts by weight), the chlorine flow is stopped to terminate the chlorination reaction. The reaction time is 2.4 hours. The stirring of the reactor 3 is carried out by a flat-paddle stirrer. During the chlorination reaction, the stirring speed of the reactor 3 is 80 rpm to avoid excessive stirring to destroy the chlorine microbubbles and ensure the shape of the chlorine microbubbles in the reactor 3.

[0023] Since the chlorination reaction is an exothermic reaction, in order to remove the heat of the reaction in time and avoid excessive local temperature affecting product quality, the pressure of reactor 3 is controlled at 0.25MPa. This not only controls the chlorine flow rate to ensure stable and uniform reaction, but also reduces the pressure of the reactor, which is beneficial to equipment safety and process operation safety.

[0024] S4. After the chlorination reaction is completed, the slurry is washed with water by a water filter 7, centrifuged by a centrifuge 8, and dried by a dryer 9 to obtain a chlorinated polyethylene product. The chlorine content of the product is 35.2% after testing.

[0025] Example 2 refer to Figure 1 and Figure 2 A method for producing chlorinated polyethylene using microbubble reaction comprises the following steps: S1. Preparation of microcapsule morphology additives By weight, 0.5 parts of surfactant, 0.5 parts of suspension stabilizer, 2.5 parts of anti-sticking agent, 0.2 parts of initiator, and 100 parts of water are added into premixing tank 1 for premixing and stirring, and each reaction aid is preliminarily dispersed; The premixed reaction aid is transported to the disperser 2, and the stirring speed of the disperser 2 is adjusted to 10,000 rpm, and high-speed mixing is performed for 20 minutes. The solid and liquid in the premixed reaction aid are mixed and broken into small particles by high-speed dispersion and shearing action to form a microcapsule-shaped aid with a particle size of about 0.3 μm suspended and dispersed in water; S2, microcapsule morphology additives and polyethylene particles adhesion and penetration 1000 parts by weight of 18 wt% hydrochloric acid solution is added to the reactor 3 as a reaction medium. When the liquid level is higher than the stirring blade, stirring is started. 200 parts by weight of high-density polyethylene and the microcapsule morphology aid formed in step 1 are added to the reactor 3, so that the microcapsule morphology aid is stably suspended and dispersed in the reaction medium. When the microcapsule morphology aid encounters polyethylene particles, it is uniformly attached to the surface of the polyethylene particles. Since the particle size of the microcapsule morphology aid is small and the pore size D50 of the polyethylene particles is about 0.4 um, the microcapsule morphology aid simultaneously penetrates into the pores of the polyethylene particles, so that the polyethylene particles can be stably dispersed in the reaction medium, thereby ensuring the uniformity of the subsequent chlorination reaction. S3, microbubble chlorination reaction After passing through the liquid chlorine vaporizer 4, the chlorine buffer tank 5, and the microbubble generator 6, the liquid chlorine forms chlorine microbubbles with a bubble diameter of 0.05 to 5 um and enters the bottom of the reactor 3. The bubbles are rich and dense. After entering the reactor 3, the chlorine microbubbles disperse in the reactor and rise slowly, ensuring the opportunity to contact with more polyethylene particles and avoiding the increase of the gas phase pressure after the chlorine rises quickly to the gas phase. Since the diameter of the chlorine microbubbles is extremely small, they can enter the pores of the polyethylene particles and react simultaneously on the surface and inside of the polyethylene particles, greatly increasing the uniformity of the chlorination reaction. Under the action of the reaction aid and temperature, the chlorine decomposes to produce chlorine free radicals, which then undergo substitution reactions with the hydrogen atoms in the polyethylene. As the reaction continues, the chlorine atoms on the polyethylene molecules gradually increase. After reaching the predetermined chlorine content (180 parts by weight), the chlorine is stopped and the chlorination reaction ends. During the reaction, the pressure of the reactor 3 is controlled at 0.25 MPa, and the reaction time is 2.5 hours. S4. After the chlorination reaction is completed, the slurry is washed with water by a water filter 7, centrifuged by a centrifuge 8, and dried by a dryer 9 to obtain a chlorinated polyethylene product. The chlorine content of the product is 34.9% after testing.

[0026] Comparative Example 1 According to the raw materials and dosage ratios of the reaction aids, polyethylene, chlorine flow rate and reaction medium in Example 1, a control production test was carried out using a traditional process.

[0027] 1000 parts by weight of water was added into the reaction kettle as a reaction medium. When the liquid level was higher than the stirring blade, stirring was started. 50 parts by weight of high-density polyethylene, 0.01 parts of a surfactant, 0.02 parts of a suspension stabilizer, and 0.01 parts of an initiator were added to prepare a suspension solution. Chlorine gas was introduced into the suspension solution for chlorination reaction, the reaction temperature was 30-120°C, the amount of chlorine gas introduced was 60 parts by weight, and the reaction time was 3.2 hours; After the chlorination reaction is completed, the slurry is washed with water, centrifuged and dried in sequence to obtain a chlorinated polyethylene product. The chlorine content of the product is 35.1% after testing.

[0028] Comparative Example 2 According to the raw materials and dosage ratios of the reaction aids, polyethylene, chlorine flow rate and reaction medium in Example 2, a control production test was carried out using a traditional process.

[0029] Add 1000 parts by weight of 18 wt% hydrochloric acid solution as a reaction medium into the reactor, start stirring when the liquid level is higher than the stirring blade, add 200 parts by weight of high-density polyethylene, 0.5 parts of a surfactant, 0.5 parts of a suspension stabilizer, 2.5 parts of an anti-sticking agent, and 0.2 parts of an initiator to prepare a suspension solution; Chlorine gas was introduced into the suspension solution for chlorination reaction, the reaction temperature was 30-120°C, the amount of chlorine gas introduced was 180 parts by weight, and the reaction time was 3.5 hours; After the chlorination reaction is completed, the slurry is washed with water, centrifuged and dried in sequence to obtain a chlorinated polyethylene product. The chlorine content of the product is 35.0% after testing.

[0030] refer to Figure 3 and Figure 4 Sample 1# shows the surface morphology and chlorine content distribution of chlorinated polyethylene particles produced by conventional process in Comparative Example 1, and sample 2# shows the surface morphology and chlorine content distribution of chlorinated polyethylene particles produced by process of the present invention in Example 1. Figure 3 and Figure 4 It can be seen that the chlorine content of the chlorinated polyethylene produced by the process of the present invention is more evenly distributed.

[0031] refer to Figure 5 Sample 1# is the thermal stability of chlorinated polyethylene produced by conventional process in comparative example 1 under 200°C environment, and sample 2# is the thermal stability of chlorinated polyethylene produced by process of the present invention in example 1 under 200°C environment. Under 200°C environment, chlorinated polyethylene particles gradually turn yellow and darker with time, and the darker the color, the more decomposition. Figure 5 It can be seen that the chlorinated polyethylene produced by the process of the present invention has better thermal stability.

[0032] The above description is only an illustrative embodiment of the present invention and is not intended to limit the scope of the present invention. For example, the ratio of each auxiliary agent and raw material, any equivalent changes and modifications made by any technician in the field without departing from the concept and principle of the present invention should fall within the scope of protection of the present invention.

Claims

1. A method for producing chlorinated polyethylene using microbubble reaction, characterized in that: The steps include: S1. Preparation of microcapsule morphology additives Each reaction aid is premixed with water and stirred evenly, and the solid and liquid in the premixed reaction aid are mixed and broken into tiny particles by high-speed dispersing and shearing action to form a microcapsule-shaped aid suspended and dispersed in water; S2, microcapsule morphology additives and polyethylene particles adhesion and penetration Adding a reaction medium into a reaction kettle, starting stirring, adding raw polyethylene and microcapsule morphology aid into the reaction kettle, making the microcapsule morphology aid stably suspended and dispersed in the reaction medium, uniformly attached to the surface of polyethylene particles, and penetrated into the pores of polyethylene particles; S3, microbubble chlorination reaction After passing through the microbubble generator, chlorine gas forms chlorine gas microbubbles and enters the bottom of the reactor, fully contacts with polyethylene particles and reaction aids, and reacts simultaneously on the surface and inside of the polyethylene particles; S4. After the chlorination reaction is completed, the chlorinated polyethylene product is obtained by washing, centrifugation and drying.

2. The method for producing chlorinated polyethylene using microbubble reaction as claimed in claim 1, characterized in that: In step S1, the dispersion shearing rotation speed is 8000 to 12000 rpm.

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

4. The method for producing chlorinated polyethylene using microbubble reaction as claimed in claim 2, characterized in that: In step S2, the pore size of the polyethylene particles is 0.2-0.6 um.

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

6. The method for producing chlorinated polyethylene using microbubble reaction as claimed in claim 1, characterized in that: The reactor is stirred using a flat-paddle stirrer.

7. The method for producing chlorinated polyethylene by microbubble reaction as claimed in claim 6, characterized in that: During the chlorination reaction, the stirring speed of the reactor is 70 to 120 rpm.

8. The method for producing chlorinated polyethylene using microbubble reaction as claimed in claim 1, characterized in that: During the chlorination reaction, the pressure in the reactor was less than 0.3 MPa.

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

10. A device for producing chlorinated polyethylene using microbubble reaction, comprising a reactor, characterized in that: It also includes a microbubble generator, which is connected to the bottom of the reactor. After the chlorine passes through the microbubble generator, chlorine microbubbles are formed and enter the bottom of the reactor.

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