Equipment and method for synthesizing chlorinated polyvinyl chloride

Abstract

The invention relates to equipment for synthesizing chlorinated polyvinyl chloride and a synthesis method thereof, and belongs to the technical field of chemical synthesis equipment. Through the synergistic effect of the cavitation effect of ultrasonic waves and the photocatalytic reaction, the ultrasonic waves generate a large number of tiny bubbles in the working solution, on one hand, the tiny bubbles just enable pvc particles with lower density to float and overflow, and photocatalyst particles with higher density are kept at the bottom, so that self-separation of reactants and a catalyst is achieved, and the self-separation effect of the reactants and the photocatalyst is improved. On the other hand, the microbubbles quickly collapse in an extremely short time after floating to the surface of the reaction liquid, a cavitation effect is generated, dispersion of the photocatalyst in the reaction stock solution can be promoted, and the contact opportunity of the photocatalyst and reactants in the reaction stock solution is increased. A local high-temperature and high-pressure environment generated when the microbubbles are broken can enhance the activity of the photocatalytic reaction, and the synergistic effect of the microbubbles and photocatalysis can accelerate the photocatalytic reaction rate, promote the chlorination reaction of chlorine and pvc particles, and improve the chlorination rate.

Description

Technical Field

[0001] The present invention relates to an apparatus for synthesizing chlorinated polyvinyl chloride and a synthesis method thereof, belonging to the technical field of chemical synthesis equipment. Background Art

[0002] At present, chlorinated polyvinyl chloride (CPVC) is a new type of high-performance plastic. It is prepared by means of reaction chlorination using polyvinyl chloride (PVC) as a raw material. The chlorine content increases from 56.8% of PVC to 60%-70%, and theoretically can reach up to 73.2% at most. Generally, the chlorine content of CPVC is 61%-68%. Due to the increase in the content of polar elements, CPVC exhibits a series of characteristics that are much superior to those of PVC: the Vicat softening temperature reaches 90-125°C, and after treatment, the maximum service temperature is 110°C, and the long-term service temperature is 95°C. It has better weather resistance, corrosion resistance and aging resistance.

[0003] The existing CPVC production processes mainly include solution method, aqueous suspension method, gas-solid phase chlorination method, and liquid chlorine chlorination method. The aqueous suspension method is the production method commonly adopted by major companies at present. However, the CPVC synthesis process by the aqueous phase method still has the disadvantages of complex product separation, serious discharge of reaction waste liquid, environmental pollution, poor production environment, and poor continuous production capacity.

[0004] In view of the above-mentioned defects, the present invention aims to create an apparatus for synthesizing chlorinated polyvinyl chloride and a synthesis method thereof, making it more valuable in industrial applications. Summary of the Invention

[0005] In order to solve the above technical problems, the object of the present invention is to provide an apparatus for synthesizing chlorinated polyvinyl chloride and a synthesis method thereof.

[0006] An apparatus for synthesizing chlorinated polyvinyl chloride according to the present invention includes a main body of the apparatus, an exhaust gas separation port installed at the top of the main body of the apparatus. The inner cavity of the main body of the apparatus is divided into multiple reaction chambers by an aeration device. Adjacent two layers are connected by an overflow pipe passing through the aeration device. The outer walls of adjacent two reaction chambers are connected through a pressure relief pipe and a pressure relief valve. An ultrasonic generator is further provided above the aeration device. Ultraviolet lamps are arranged on the side walls of each divided reaction chamber. A raw material inlet and a product outlet are respectively arranged on the top and bottom side walls of the main body of the apparatus. A chlorine gas storage tank is further provided outside the main body of the apparatus. The chlorine gas storage tank is respectively connected to each aeration device through an inlet pipe and an inlet valve.

[0007] Further, the divided reaction chambers are 3-5 layers, and the height of each layer of reaction chamber is 1 m.

[0008] Further, the raw material gas in the chlorine gas storage tank is a mixed gas of chlorine gas and nitrogen gas, and the chlorine gas concentration is 55%-60%.

[0009] Further, the operating temperature of the device body is 60 to 120 °C.

[0010] Further, the frequency of the ultrasonic generator is 20 to 30 kHz, and the power is 60 kW.

[0011] A method for synthesizing chlorinated polyvinyl chloride using a device for synthesizing chlorinated polyvinyl chloride, and the specific synthesis steps are as follows:

[0012] (1) Mix PVC resin particles, polyvinyl alcohol, nano-titanium dioxide, and water evenly to obtain a reaction stock solution, adjust the pH of the reaction stock solution to neutral with sodium bicarbonate, and then displace the gas in the reaction stock solution with nitrogen to exclude internal oxygen;

[0013] (2) Feed the above reaction stock solution into the device body from the top raw material inlet, and maintain the feeding speed so that the reaction stock solution entering the device body stays in each reaction chamber for 30 to 40 minutes. When the reaction stock solution enters the reaction chamber of the device body, turn on the aeration device and control the chlorine intake through the intake valve until the pressure in the reaction chamber reaches 0.98 Mpa;

[0014] (3) When the pressure of the fed chlorine is stable, stop the ventilation, turn on the ultrasonic generator and the ultraviolet lamp, and perform aeration ultrasonic photocatalytic reaction. Control the reaction temperature at 80 to 100 °C. After the reaction reaches the residence time of each layer, continue to feed the reaction stock solution, and let the reaction solution of the upper layer overflow from the overflow pipe into the lower reaction chamber for continuous reaction. After the reaction is completed, discharge from the product discharge port at the bottom, and at the same time open the pressure relief valve so that the waste gas goes upward through the pressure relief pipe and is finally separated and discharged through the waste gas separation port;

[0015] (4) Wash the obtained reaction product repeatedly with deionized water until the pH of the washing solution is neutral, then dehydrate by centrifugation to reduce the water content of the chlorinated polyvinyl chloride to 20% to 30%, and further dry it with a fluidized bed dryer until the water content is 0.3% to finally obtain the finished product of chlorinated polyvinyl chloride.

[0016] Further, in the step (1), by weight, the PVC resin particles are 100 to 120 parts, the polyvinyl alcohol is 0.05 to 0.2 parts, the nano-titanium dioxide is 3 to 5 parts, and the water is 300 to 500 parts.

[0017] Further, in the step (1), the particle size of the PVC resin particles is 50 to 80 μm, the degree of polymerization is 700 to 1000, and the apparent density is 0.48 to 0.52 g / ml.

[0018] By means of the above solution, the present invention has at least the following advantages:

[0019] (1) The present invention selects special granular and loose PVC resin particles to ensure that chlorine gas can more easily diffuse into the interior of the particles during the reaction, ensuring uniform distribution of chlorine elements in the product. At the same time, a dispersant is added to prevent agglomeration of the particles during the reaction process, thereby increasing the chlorine content of the final product;

[0020] (2) The present invention also sets up an ultrasonic generator and an ultraviolet lamp. Through the synergistic effect of the cavitation effect of ultrasonic waves and photocatalytic reaction, a large number of tiny bubbles are generated in the working fluid. On the one hand, these tiny bubbles can just make the PVC particles with lower density float and overflow, while the photocatalyst particles with higher density remain at the bottom, thus realizing the self-separation of the reactants and the catalyst and improving the product purity. On the other hand, these microbubbles will quickly collapse in a very short time after floating to the surface of the reaction solution, generating a cavitation effect, instantaneously generating a high-temperature and high-pressure environment, accompanied by strong shock waves and microjets, which can promote the dispersion of the photocatalyst in the reaction stock solution and increase the contact opportunity between the photocatalyst and the reactants in the reaction stock solution. At the same time, the locally high-temperature and high-pressure environment generated when the microbubbles burst can enhance the activity of the photocatalytic reaction. The synergistic effect of the microbubbles and photocatalysis can accelerate the photocatalytic reaction rate, promote the completion of the chlorination reaction between chlorine gas and PVC particles, and increase the chlorination rate;

[0021] (3) The multi-layer reaction chamber structure designed by the present invention enables the PVC particles to gradually descend in the equipment main body and undergo chlorination reactions, with the chlorine content gradually increasing. When reaching the bottom layer, the required chlorinated polyvinyl chloride product is obtained.

[0022] The above description is only an overview of the technical solution of the present invention. In order to be able to more clearly understand the technical means of the present invention and implement it in accordance with the content of the specification, the following takes the preferred embodiments of the present invention and describes them in detail in conjunction with the accompanying drawings as follows. Description of the Drawings

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show a certain embodiment of the present invention, and therefore should not be regarded as a limitation of the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0024] Figure 1 is a schematic structural diagram of the equipment for synthesizing chlorinated polyvinyl chloride of the present invention;

[0025] Among them, in the figure:

[0026] 1. Equipment main body; 2. Raw material inlet; 3. Product discharge port; 4. Chlorine gas storage tank; 5. Exhaust gas separation port; 6. Overflow pipe; 7. Ultrasonic generator; 8. Aeration device; 9. Ultraviolet lamp; 11. Pressure relief pipe; 12. Pressure relief valve; 41. Inlet pipe; 42. Inlet valve. Detailed implementation manner

[0027] The following combines the drawings and embodiments to further describe in detail the specific implementation manner of the present invention. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0028] See Figure 1 , a device for synthesizing chlorinated polyvinyl chloride according to a preferred embodiment of the present invention, includes an equipment main body 1 and an exhaust gas separation port 5 installed on the top of the equipment main body 1 for separating and removing the exhaust gas generated during the reaction in the equipment. The inner cavity of the equipment main body 1 is divided into 3 to 5 reaction chambers by an aeration device 8, and the height of each reaction chamber is 1 m. Adjacent layers are connected by an overflow pipe 6 passing through the aeration device 8, and the outer walls of adjacent reaction chambers are connected by a pressure relief pipe 11 and a pressure relief valve 12. An ultrasonic generator 7 is also provided above the aeration device 8. Ultraviolet lamps 9 are provided on the side walls of each divided reaction chamber. A raw material inlet 2 and a product discharge port 3 are respectively provided on the top and bottom side walls of the equipment main body 1. A chlorine gas storage tank 4 is also provided outside the equipment main body 1. The chlorine gas storage tank 4 is respectively connected to each aeration device 8 through an inlet pipe 41 and an inlet valve 42.

[0029] The raw material gas in the chlorine gas storage tank 4 is a mixed gas of chlorine and nitrogen, and the chlorine concentration is 55 - 60%; the equipment main body 1 can be heated to 60 - 120 °C through a coil, and the working temperature of the equipment main body 1 is 60 - 120 °C;

[0030] The frequency of the ultrasonic generator 7 is 20 - 30 kHz, and the power is 60 kW; the present invention sets a low-frequency ultrasonic frequency with a better cavitation effect to facilitate the generation of ultrasonic cavitation effect in the later stage.

[0031] The specific steps for synthesizing chlorinated polyvinyl chloride are as follows:

[0032] (1) By weight, 100 - 120 parts of PVC resin particles with a particle size of 50 - 80 μm, a degree of polymerization of 700 - 1000, and an apparent density of 0.48 - 0.52 g / ml, 0.05 - 0.2 parts of polyvinyl alcohol, 3 - 5 parts of nano-titanium dioxide, and 300 - 500 parts of water are mixed evenly to obtain a reaction stock solution. The pH of the reaction stock solution is adjusted to neutral with sodium bicarbonate, and then the reaction stock solution is subjected to gas displacement with nitrogen to remove internal oxygen;

[0033] The present invention selects special granular and loose PVC resin particles to ensure that chlorine gas can diffuse more easily into the interior of the particles during the reaction, ensuring uniform distribution of chlorine elements in the product. At the same time, a dispersant is added to prevent agglomeration of the particles during the reaction process;

[0034] (2) Feed the above reaction stock solution into the equipment main body 1 from the top raw material inlet 2, and maintain the feeding speed so that the reaction stock solution entering the equipment main body 1 stays in each reaction chamber for 30 - 40 minutes. After the reaction stock solution enters the reaction chamber of the equipment main body 1, turn on the aeration device 8, and control the chlorine gas intake through the intake valve 42 until the pressure in the reaction chamber reaches 0.98 Mpa;

[0035] (3) When the pressure of the fed chlorine gas is stable, stop the gas supply, turn on the ultrasonic generator 7 and the ultraviolet lamp 9, and perform aeration ultrasonic photocatalytic reaction. Control the reaction temperature at 80 - 100 °C. After the reaction reaches the residence time of each layer, continue to feed the reaction stock solution, and let the reaction solution of the upper layer overflow into the lower layer reaction chamber through the overflow pipe 6 for continuous reaction. After the reaction is completed, discharge from the product discharge port 3 at the bottommost part, and at the same time, turn on the pressure relief valve 12 so that the waste gas goes upward through the pressure relief pipe 11 and is finally separated and discharged through the waste gas separation port 5;

[0036] The present invention is also provided with an ultrasonic generator and an ultraviolet lamp. Through the synergistic effect of the cavitation effect of ultrasonic waves and photocatalytic reaction, a large number of tiny bubbles are generated in the working fluid by ultrasonic waves. On the one hand, these tiny bubbles can just make the PVC particles with lower density float and overflow, while the photocatalyst particles with higher density remain at the bottom, thus realizing the self - separation of the reactants and the catalyst and improving the product purity. On the other hand, these micro - bubbles will quickly collapse in an extremely short time after floating to the surface of the reaction solution, generating a cavitation effect, instantaneously generating a high - temperature and high - pressure environment, accompanied by strong shock waves and micro - jets, which can promote the dispersion of the photocatalyst in the reaction stock solution and increase the contact opportunity between the photocatalyst and the reactants in the reaction stock solution. At the same time, the locally high - temperature and high - pressure environment generated when the micro - bubbles burst can enhance the activity of the photocatalytic reaction. The synergistic effect of micro - bubbles and photocatalysis can accelerate the photocatalytic reaction rate, promote the completion of the chlorination reaction between chlorine gas and PVC particles, and improve the chlorination rate;

[0037] The multi - layer reaction chamber structure designed by the present invention enables the PVC particles to gradually descend in the equipment main body 1 and undergo chlorination reaction, with the chlorine content gradually increasing. When reaching the bottommost layer, the required chlorinated polyvinyl chloride product is obtained.

[0038] (4) Wash the obtained reaction product repeatedly with deionized water until the pH of the washing solution is neutral, then dehydrate by centrifugation to reduce the water content of the chlorinated polyvinyl chloride to 20% - 30%, and further dry it with a fluidized bed dryer until the water content is 0.3% to finally obtain the finished product of chlorinated polyvinyl chloride.

[0039] Example 1

[0040] An apparatus for synthesizing chlorinated polyvinyl chloride, comprising a main body 1 of the apparatus, an exhaust gas separation port 5 installed at the top of the main body 1 of the apparatus for separating and removing the exhaust gas generated during the reaction in the apparatus. The inner cavity of the main body 1 of the apparatus is divided into 4 reaction chambers by an aeration device 8, the height of each reaction chamber is 1 m, and adjacent two layers are connected by an overflow pipe 6 passing through the aeration device 8. The outer walls of adjacent two reaction chambers are connected through a pressure relief pipe 11 and a pressure relief valve 12. An ultrasonic generator 7 is further provided above the aeration device 8. An ultraviolet lamp 9 is provided on the side wall of each separated reaction chamber. A raw material inlet 2 and a product discharge port 3 are respectively provided on the top and bottom side walls of the main body 1 of the apparatus. A chlorine gas storage tank 4 is further provided outside the main body 1 of the apparatus. The chlorine gas storage tank 4 is respectively connected and communicated with each aeration device 8 through an inlet pipe 41 and an inlet valve 42.

[0041] The raw material gas in the chlorine gas storage tank 4 is a mixed gas of chlorine gas and nitrogen gas, and the chlorine gas concentration is 55%; the main body 1 of the apparatus can be heated to 60 °C through a coil pipe, and the working temperature of the main body 1 of the apparatus is 60 °C;

[0042] The frequency of the ultrasonic generator 7 is 20 kHz and the power is 60 kW;

[0043] The specific steps for synthesizing chlorinated polyvinyl chloride are as follows:

[0044] (1) By weight, 100 parts of PVC resin particles with a particle size of 50 μm, a degree of polymerization of 700, and an apparent density of 0.48 g / ml, 0.05 part of polyvinyl alcohol, 3 parts of nano-titanium dioxide, and 300 parts of water are mixed evenly to obtain a reaction stock solution. The pH of the reaction stock solution is adjusted to neutral with sodium bicarbonate, and then the reaction stock solution is subjected to gas displacement with nitrogen to exclude the internal oxygen;

[0045] (2) The above reaction stock solution is introduced into the main body 1 of the apparatus from the top raw material inlet 2, and the introduction speed is maintained so that the reaction stock solution entering the main body 1 of the apparatus stays in each reaction chamber for 30 min. After the reaction stock solution enters the reaction chamber of the main body 1 of the apparatus, the aeration device 8 is turned on, and the chlorine gas intake is controlled through the inlet valve 42 until the pressure in the reaction chamber reaches 0.98 Mpa;

[0046] (3) After the pressure of the introduced chlorine gas becomes stable, stop the gas supply, turn on the ultrasonic generator 7 and the ultraviolet lamp 9, and conduct the aeration ultrasonic photocatalysis reaction. Control the reaction temperature at 80 °C. After the reaction reaches the residence time for each layer, continue to introduce the reaction stock solution, and let the reaction solution from the upper layer overflow into the lower layer reaction chamber through the overflow pipe 6 for continuous reaction. After the reaction is completed, discharge the product from the product discharge port 3 at the bottom, and at the same time, turn on the pressure relief valve 12 so that the waste gas goes upward through the pressure relief pipe 11 and is finally separated and discharged through the waste gas separation port 5;

[0047] (4) Wash the obtained reaction product repeatedly with deionized water until the pH of the washing solution is neutral, then dehydrate by centrifugation to reduce the water content of the chlorinated polyvinyl chloride to 20%, and further dry it with a fluidized bed dryer until the water content is 0.3% to finally obtain the finished product of chlorinated polyvinyl chloride.

[0048] Example 2

[0049] An apparatus for synthesizing chlorinated polyvinyl chloride, comprising a device main body 1, a waste gas separation port 5 installed at the top of the device main body 1 for separating and removing the waste gas generated during the reaction in the device. The inner cavity of the device main body 1 is divided into 4 layers of reaction chambers by an aeration device 8, and the height of each layer of reaction chamber is 1 m. The adjacent two layers are connected by an overflow pipe 6 passing through the aeration device 8. The outer walls of the adjacent two layers of reaction chambers are connected by a pressure relief pipe 11 and a pressure relief valve 12. An ultrasonic generator 7 is also provided above the aeration device 8, and an ultraviolet lamp 9 is provided on the side wall of each divided reaction chamber. A raw material inlet 2 and a product discharge port 3 are respectively provided on the top and bottom side walls of the device main body 1. A chlorine gas storage tank 4 is further provided outside the device main body 1, and the chlorine gas storage tank 4 is respectively connected to each aeration device 8 through an inlet pipe 41 and an inlet valve 42.

[0050] The raw material gas in the chlorine gas storage tank 4 is a mixed gas of chlorine gas and nitrogen gas, and the chlorine gas concentration is 58%; the device main body 1 can be heated to 80 °C through a coil, and the working temperature of the device main body 1 is 90 °C;

[0051] The frequency of the ultrasonic generator 7 is 25 kHz and the power is 60 kW;

[0052] The specific steps for synthesizing chlorinated polyvinyl chloride are as follows:

[0053] (1) By weight, mix 110 parts of PVC resin particles with a particle size of 65 μm, a degree of polymerization of 850, and an apparent density of 0.5 g / ml, 0.1 part of polyvinyl alcohol, 4 parts of nano-titanium dioxide, and 400 parts of water evenly to obtain a reaction stock solution. Adjust the pH of the reaction stock solution to neutral with sodium bicarbonate, and then conduct gas replacement on the reaction stock solution with nitrogen to remove the internal oxygen;

[0054] (2) Feed the above reaction stock solution into the equipment main body 1 from the top raw material inlet 2, and maintain the feeding speed so that the reaction stock solution entering the equipment main body 1 stays in each reaction chamber for 35 minutes. After the reaction stock solution enters the reaction chamber of the equipment main body 1, turn on the aeration device 8, and control the chlorine intake through the intake valve 42 until the pressure in the reaction chamber reaches 0.98 Mpa;

[0055] (3) After the pressure of the fed chlorine is stable, stop the ventilation, turn on the ultrasonic generator 7 and the ultraviolet lamp 9, and perform the aeration ultrasonic photocatalytic reaction. Control the reaction temperature at 90 °C. After the reaction reaches the residence time of each layer, continue to feed the reaction stock solution, and let the reaction solution of the upper layer overflow from the overflow pipe 6 into the lower layer reaction chamber for continuous reaction. After the reaction is completed, discharge from the product discharge port 3 at the bottom, and at the same time turn on the pressure relief valve 12 so that the waste gas goes upward through the pressure relief pipe 11 and is finally separated and discharged through the waste gas separation port 5;

[0056] (4) Wash the obtained reaction product repeatedly with deionized water until the pH of the washing solution is neutral, then perform centrifugal dehydration to reduce the water content of the chlorinated polyvinyl chloride to 25%, and further dry it with a fluidized bed dryer until the water content is 0.3% to finally obtain the finished product of chlorinated polyvinyl chloride.

[0057] Example 3

[0058] An equipment for synthesizing chlorinated polyvinyl chloride includes an equipment main body 1 and a waste gas separation port 5 installed at the top of the equipment main body 1 for separating and removing the waste gas generated during the reaction in the equipment. The inner cavity of the equipment main body 1 is divided into 5 reaction chambers by an aeration device 8, the height of each reaction chamber is 1 m, and adjacent layers are connected by an overflow pipe 6 passing through the aeration device 8. The outer walls of adjacent reaction chambers are connected by a pressure relief pipe 11 and a pressure relief valve 12. An ultrasonic generator 7 is also provided above the aeration device 8, and an ultraviolet lamp 9 is provided on the side wall of each divided reaction chamber. A raw material inlet 2 and a product discharge port 3 are respectively provided on the top and bottom side walls of the equipment main body 1. A chlorine gas storage tank 4 is also provided outside the equipment main body 1, and the chlorine gas storage tank 4 is respectively connected and communicated with each aeration device 8 through an inlet pipe 41 and an intake valve 42.

[0059] The raw material gas in the chlorine gas storage tank 4 is a mixed gas of chlorine and nitrogen, and the chlorine concentration is 60%; the equipment main body 1 can be heated to 120 °C through a coil, and the working temperature of the equipment main body 1 is 120 °C;

[0060] The frequency of the ultrasonic generator 7 is 30 kHz and the power is 60 kW;

[0061] The specific steps for synthesizing chlorinated polyvinyl chloride are as follows:

[0062] (1) By weight, 120 parts of PVC resin particles with a particle size of 80 μm, a degree of polymerization of 1000, and an apparent density of 0.52 g / ml, 0.2 part of polyvinyl alcohol, 5 parts of nano-titanium dioxide, and 500 parts of water are mixed evenly to obtain a reaction stock solution. The pH of the reaction stock solution is adjusted to neutral with sodium bicarbonate, and then the reaction stock solution is purged with nitrogen to remove internal oxygen;

[0063] (2) The above reaction stock solution is introduced into the equipment main body 1 from the top raw material inlet 2, and the introduction speed is maintained so that the reaction stock solution entering the equipment main body 1 stays in each reaction chamber for 40 min. After the reaction stock solution enters the reaction chamber of the equipment main body 1, the aeration device 8 is turned on, and the chlorine gas intake is controlled through the intake valve 42 until the pressure in the reaction chamber reaches 0.98 Mpa;

[0064] (3) After the pressure of the introduced chlorine gas is stabilized, the gas supply is stopped, the ultrasonic generator 7 and the ultraviolet lamp 9 are turned on for aeration ultrasonic photocatalytic reaction, and the reaction temperature is controlled at 100 °C. After the reaction reaches the residence time of each layer, the reaction stock solution is continuously introduced, and the reaction solution of the upper layer overflows from the overflow pipe 6 into the lower layer reaction chamber for continuous reaction. After the reaction is completed, the product is discharged from the bottom product discharge port 3, and at the same time, the pressure relief valve 12 is opened so that the waste gas goes upward through the pressure relief pipe 11 and is finally separated and discharged through the waste gas separation port 5;

[0065] (4) The obtained reaction product is repeatedly washed with deionized water until the pH of the washing solution is neutral, and then centrifuged to reduce the water content of the chlorinated polyvinyl chloride to 30%, and further dried with a fluidized bed dryer to a water content of 0.3% to finally obtain a chlorinated polyvinyl chloride finished product.

[0066] Example 4

[0067] The preparation method of this example is basically the same as that of Example 2, except that the PVC resin particles used in step 1 have a particle size of 100 μm, a degree of polymerization of 1500, and an apparent density of 0.6 g / ml, and other preparation conditions remain unchanged, and a chlorinated polyvinyl chloride finished product is also obtained;

[0068] Example 5

[0069] The preparation method of this example is basically the same as that of Example 2, except that the inner cavity of the equipment main body 1 is divided into 2 reaction chambers by the aeration device, and other preparation conditions remain unchanged, and a chlorinated polyvinyl chloride finished product is also obtained;

[0070] Example 6

[0071] The preparation method of this example is basically the same as that of Example 2, except that the inner cavity of the equipment main body 1 is divided into 6 reaction chambers by the aeration device, and other preparation conditions remain unchanged, and a chlorinated polyvinyl chloride finished product is also obtained;

[0072] Example 7

[0073] The preparation method of this example is basically the same as that of Example 2, except that the ultrasonic frequency of the ultrasonic generator is 40 kHz, and other preparation conditions remain unchanged. The finished product of chlorinated polyvinyl chloride is also obtained.

[0074] Control Example

[0075] Control Example 1

[0076] The preparation method of this control example is basically the same as that of Example 2, except that the ultrasonic generator is not used, and other preparation conditions remain unchanged. The finished product of chlorinated polyvinyl chloride is also obtained.

[0077] Performance Detection

[0078] The performance of Examples 1-6 and Control Example 1 of the present invention was detected respectively, and the detection results are shown in Table 1:

[0079] Detection Method

[0080] Chlorine content detection: The mass fraction of chlorine element in the sample was determined by oxygen bomb combustion method combined with potentiometric titration method (refer to GB / T 9349-2008)

[0081] Chlorine distribution uniformity detection: The chlorine element distribution in the particle cross-section was detected by scanning electron microscope (SEM) combined with energy dispersive X-ray spectroscopy (EDS);

[0082] Table 1 Performance Detection Results

[0083]

[0084]

[0085] It can be seen from the detection data in the above table that:

[0086] In Control Example 1, ultrasonic was not used, and the chlorination rate (73.6%) and purity (monomer residue 0.72%) were significantly lower than those of the examples, verifying the core role of ultrasonic cavitation effect in catalyst separation and reaction acceleration.

[0087] In Example 7, high-frequency ultrasonic (40 kHz) was used, and the effect was inferior to that of low-frequency (20-30 kHz), indicating that low-frequency is more conducive to the generation of cavitation effect.

[0088] Furthermore, it is confirmed that the present invention simultaneously sets an ultrasonic generator and an ultraviolet lamp. Through the synergistic effect of the cavitation effect of ultrasonic waves and the photocatalytic reaction, a large number of tiny bubbles are generated in the working fluid. On the one hand, these tiny bubbles can just make the pvc particles with lower density float and overflow, while the photocatalyst particles with higher density remain at the bottom, thus realizing the self-separation of the reactants and the catalyst, improving the product purity. On the other hand, these microbubbles will rapidly collapse in a very short time after floating to the surface of the reaction solution, generating a cavitation effect, instantaneously generating a high-temperature and high-pressure environment, accompanied by strong shock waves and microjets at the same time, which can promote the dispersion of the photocatalyst in the original reaction solution and increase the contact opportunity between the photocatalyst and the reactants in the original reaction solution. At the same time, the locally high-temperature and high-pressure environment generated when the microbubbles burst can enhance the activity of the photocatalytic reaction. The synergistic effect of the microbubbles and the photocatalysis can accelerate the photocatalytic reaction rate, promote the chlorine gas and pvc particles to complete the chlorination reaction, and improve the chlorination rate;

[0089] Example 4 uses large-particle-size (100μm), high-polymerization-degree PVC, and the chlorine content and uniformity decrease, which confirms that the particle size and looseness are the key factors for chlorine diffusion.

[0090] Furthermore, it is confirmed that the present invention selects pvc resin particles with special particle size and looseness, ensuring that chlorine gas can more easily diffuse into the particles for reaction during the reaction process, ensuring uniform distribution of chlorine elements in the product. At the same time, a dispersant is added to prevent the particles from agglomerating during the reaction process, improving the chlorine content of the final product;

[0091] The performance of Example 2 (4 layers) is the best. Too few layers (2 layers) lead to insufficient reaction, and too many layers (6 layers) do not significantly improve the effect, indicating that 4-5 layers are the optimal design.

[0092] It is confirmed that the present invention selects pvc resin particles with special particle size and looseness, ensuring that chlorine gas can more easily diffuse into the particles for reaction during the reaction process, ensuring uniform distribution of chlorine elements in the product. At the same time, a dispersant is added to prevent the particles from agglomerating during the reaction process, improving the chlorine content of the final product;

[0093] The relationship between temperature and chlorination rate:

[0094] The chlorination rate of Example 3 (120°C) is lower than that of Example 2 (90°C), indicating that high temperature may reduce the solubility of chlorine gas in the reaction solution, and it is necessary to balance the temperature and the reaction efficiency.

[0095] In summary, the present invention significantly improves the chlorination efficiency, product purity, and chlorine distribution uniformity of chlorinated polyvinyl chloride through ultrasonic and ultraviolet synergy, special particle selection, and multi-layer reaction chamber design, confirming the scientificity and effectiveness of the technical solution.

[0096] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. An apparatus for synthesizing chlorinated polyvinyl chloride, characterized in that: It includes a device main body and an exhaust gas separation port installed at the top of the device main body. Inside the device main body, its inner cavity is divided into multiple reaction chambers by an aeration device. The adjacent two layers are connected by an overflow pipe passing through the aeration device. The outer walls of the adjacent two reaction chambers are connected through a pressure relief pipe and a pressure relief valve. An ultrasonic generator is also provided above the aeration device. Ultraviolet lamps are arranged on the side walls of each divided reaction chamber. A raw material inlet and a product discharge port are respectively arranged on the top and bottom side walls of the device main body. A chlorine gas storage tank is also provided outside the device main body. The chlorine gas storage tank is respectively connected to each aeration device through an inlet pipe and an inlet valve.

2. The device for synthesizing chlorinated polyvinyl chloride according to claim 1, characterized in that: The divided reaction chambers are 3 to 5 layers, and the height of each layer of the reaction chamber is 1 m.

3. The equipment for synthesizing chlorinated polyvinyl chloride according to claim 1, characterized in that: The raw material gas in the chlorine gas storage tank is a mixed gas of chlorine and nitrogen, and the chlorine concentration is 55% to 60%.

4. An apparatus for synthesizing chlorinated polyvinyl chloride according to claim 1, characterized in that: The working temperature of the device main body is 60 to 120 °C.

5. The device for synthesizing chlorinated polyvinyl chloride according to claim 1, characterized in that: The frequency of the ultrasonic generator is 20 to 30 kHz, and the power is 60 kW.

6. A method for synthesizing chlorinated polyvinyl chloride using the apparatus for synthesizing chlorinated polyvinyl chloride according to claim 1, characterized in that: The specific synthesis steps are as follows: (1) Mix PVC resin particles, polyvinyl alcohol, nano-titanium dioxide, and water evenly to obtain a reaction stock solution. Adjust the pH of the reaction stock solution to neutral with sodium bicarbonate, and then perform gas displacement on the reaction stock solution with nitrogen to exclude internal oxygen. (2) Pass the above reaction stock solution into the device main body from the top raw material inlet, and maintain the feeding speed so that the reaction stock solution entering the device main body stays in each reaction chamber for 30 to 40 minutes. When the reaction stock solution enters the reaction chamber of the device main body, turn on the aeration device and control the chlorine gas intake through the inlet valve until the pressure in the reaction chamber reaches 0.98 Mpa. (3) When the pressure of the introduced chlorine gas is stable, stop the gas supply, turn on the ultrasonic generator and the ultraviolet lamp, and perform aeration ultrasonic photocatalytic reaction. Control the reaction temperature at 80 to 100 °C. After the reaction reaches the residence time of each layer, continue to pass the reaction stock solution, and let the reaction liquid of the upper layer overflow from the overflow pipe into the lower reaction chamber for continuous reaction. After the reaction is completed, discharge from the product discharge port at the bottom, and at the same time turn on the pressure relief valve so that the waste gas goes upward through the pressure relief pipe and is finally separated and discharged through the exhaust gas separation port. (4) Wash the obtained reaction product repeatedly with deionized water until the pH of the washing liquid is neutral, then dehydrate by centrifugation to reduce the water content of the chlorinated polyvinyl chloride to 20% to 30%, and further dry with a fluidized bed dryer until the water content is 0.3% to finally obtain the finished product of chlorinated polyvinyl chloride.

7. The method for synthesizing chlorinated polyvinyl chloride according to claim 6, characterized in that: In the step (1), by weight, the PVC resin particles are 100 to 120 parts, the polyvinyl alcohol is 0.05 to 0.2 parts, the nano-titanium dioxide is 3 to 5 parts, and the water is 300 to 500 parts.

8. The method for synthesizing chlorinated polyvinyl chloride according to claim 6, wherein: In the step (1), the particle size of the PVC resin particles is 50 to 80 μm, the degree of polymerization is 700 to 1000, and the apparent density is 0.48 to 0.52 g / ml.

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