A kind of synthesis process of diacetone acrylamide

Abstract

The present invention relates to the field of organic synthesis, and discloses a synthesis process of diacetone acrylamide, comprising the following steps: S1: first adding concentrated sulfuric acid into a reactor, then dripping a mixture of acrylonitrile and diacetone alcohol while stirring, then heating the system temperature to 40-48°C, reacting for 4-4.5h, and obtaining a mixed solution; S2: cooling the mixed solution in S1 to 12-15°C through a cooling device, and then slowly adding the mixed solution into 25% ammonia water, controlling the temperature at 25-30°C during the liquid addition process, and adjusting the pH to 7.6-8 after the liquid addition is completed. The process flow of the present invention is operated by two steps of water extraction and salting out, respectively removing most of the organic and inorganic impurities, and removing most of the acrylamide by alkali solution washing, so that the mother liquor of the reduced pressure distillation contains only a small amount of impurities, no polymerization reaction occurs during the distillation process, and the product obtained after the distillation is relatively pure, no recrystallization is required, the yield is stable, and it is good for the environment.

Description

Technical Field

[0001] The invention relates to the field of organic synthesis, and in particular to a synthesis process of diacetone acrylamide. Background Art

[0002] Diacetone acrylamide (DAAm) is a new type of vinyl functional monomer. It has two reactive groups: N-substituted amide and ketone. It is very easy to copolymerize with other vinyl monomers, thereby introducing ketone carbon groups into polymers. The active chemical properties of ketone carbon groups can make polymers undergo crosslinking and grafting reactions. It is used to prepare various adhesives, thickeners, paper reinforcing agents, crosslinking agents, etc. It is a very important chemical product. At present, there are continuous reports on the application of DAAm abroad, but there are not many studies on the synthesis of this product, and the existing literature methods are not perfect.

[0003] According to literature reports, the synthesis of diacetone acrylamide mainly consists of the following four routes: 1. Using acrylamide and diacetone alcohol as raw materials and heteropoly acid or cation exchange resin as catalyst; 2. Using acrylamide and isopropyl alcohol as raw materials and heteropoly acid or cation exchange resin as catalyst; 3. Using diacetone alcohol and acrylonitrile as raw materials and concentrated sulfuric acid as catalyst; 4. Using acetone and acrylonitrile as raw materials and concentrated sulfuric acid as catalyst; Among them, the patent with patent application number CN201710612629.5 proposes a preparation method of high-purity diacetone acrylamide. The method introduced in the literature is to subject the crude product of the reaction to vacuum distillation and then recrystallize it in benzene-petroleum ether solvent to obtain DAAM. This method not only pollutes the environment, but also during the vacuum distillation process, as the temperature increases, some impurities are prone to cause polymerization of vinyl monomers, making the yield of the product unstable. In addition, due to the low melting point of DAAM, the recrystallization process needs to be carried out at a lower temperature, which also increases the production cost.

[0004] Therefore, it is necessary to invent a synthesis process of diacetone acrylamide to solve the above problems. Summary of the invention

[0005] The object of the present invention is to provide a synthesis process of diacetone acrylamide to solve the problems raised in the above background technology.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical scheme: A synthesis process of diacetone acrylamide, comprising the following steps: S1: first add concentrated sulfuric acid to a reactor, then add a mixture of acrylonitrile and diacetone alcohol dropwise while stirring, then raise the system temperature to 40-48°C, and react for 4-4.5h to obtain a mixed solution; S2: cool the mixed solution in S1 to 12-15°C through a cooling device, and then slowly add the mixed solution to 25% ammonia water, control the temperature at 25-30°C during the addition process, and adjust the pH to 7.6-8 after the addition is completed; S3: filter the mixed solution in S2, add distilled water to the filtrate, shake well, let stand, and then separate the layers, and use NaCl to salt out the water layer to separate the organic layer; S4: add 15% NaOH solution to the organic layer, stir well for 30-40min, and again reduce the temperature to 15-25°C through a cooling device, and then let stand to separate the layers; S5: Add an inhibitor to the organic layer in S4, and then perform reduced pressure distillation under an absolute vacuum condition of 6 MPa, collect the distillate at a temperature of 120-130° C., and obtain diacetone acrylamide.

[0007] The process of the invention is simple, diacetone alcohol and acrylonitrile are synthesized in one step, the yield is high, and no solvents such as petroleum ether are used in the synthesis process, which is more environmentally friendly and has a high synthesis rate.

[0008] The molar ratio of acrylonitrile, diacetone alcohol and sulfuric acid is 1.2:0.25:2.0-2.5.

[0009] Preferably, the cooling device comprises a cooling box, an L-shaped plate and an inclined cooling plate, the inclined cooling plate is located inside the cooling box, a plurality of inclined cooling plates are provided, and the plurality of inclined cooling plates are arranged linearly and equidistantly from top to bottom inside the cooling box, and the inclined cooling plates of the upper layer are inclined in opposite directions to the inclined cooling plates of the lower layer, a leakage hole is provided at the bottom end of the inclined cooling plate, a water outlet groove is provided at the inner wall of the cooling box at the position at the bottom end of the inclined cooling plate, the water outlet groove is located above the inclined cooling plate, an opening and closing mechanism for controlling the opening and closing of the leakage hole and the water outlet groove is provided in the cooling box, a temperature sensor is fixed at a position near the bottom end of the upper surface of the inclined cooling plate, and the outer wall of the cooling box is connected to the bottom wall of the inclined cooling plate. A water outlet pipe is fixedly provided at a position corresponding to the water outlet trough, and the water outlet pipe is interconnected with several groups of water outlet troughs. A cold water cavity is opened inside the inclined cooling plate, and the cold water cavity is interconnected with a water delivery cavity provided in the cooling box wall, and the bottom end of the water delivery cavity is interconnected with a cold water inlet pipe, and the bottom end of the cold water inlet pipe is interconnected with a water pump inside the cold water circulation box, and the top of the water delivery cavity is interconnected with a cold water outlet pipe, and the bottom end of the cold water outlet pipe is inserted into the cold water circulation box. A liquid inlet pipe is fixedly provided on the top side wall of the cooling box, and an L-shaped plate is fixedly provided on the top of the cooling box, and water discharge holes are evenly opened on the bottom of the L-shaped plate. A controller is fixedly provided on the inner wall of the cooling box, and the controller is electrically connected to the temperature sensor and the opening and closing mechanism.

[0010] During operation, the mixed liquid can be input into the cooling box from the liquid inlet pipe, and the mixed liquid first enters the sealing area between the L-shaped plate and the cooling box, and then the mixed liquid will leak out evenly from the drain hole at the bottom of the L-shaped plate, and then will fall on the surface of the inclined cooling plate on the top layer, flow down along the surface of the inclined cooling plate, and leak out again from the leakage hole on the inclined cooling plate to enter the surface of the next group of inclined cooling plates. Since the interior of the cold water chamber is full of cold water, the surface temperature of the inclined cooling plate is relatively low, and the mixed liquid passing through its surface can be cooled. The cold water circulation box, the cold water outlet pipe and the cold water inlet pipe can circulate the cold water inside the cold water chamber, so that the temperature of the water inside the cold water chamber is always low. The present invention arranges a plurality of groups of inclined cooling plates inside the cooling box, so that the mixed liquid flows evenly from the drain hole at the bottom of the L-shaped plate, and then flows through the surface of the inclined cooling plate from top to bottom in sequence, and enters Increasing the spreading area of ​​the mixed liquid on the surface of the inclined cooling plate can increase the heat exchange effect, and then the mixed liquid can be cooled quickly. Compared with direct natural cooling or the use of a fan cooling machine, this can greatly improve production efficiency and thus improve economic benefits. In actual application, when the mixed liquid flows to the temperature sensor at the bottom of the inclined cooling plate, the temperature sensor can test the temperature of the mixed liquid. When the temperature meets the requirements, the controller will control the opening and closing mechanism to start, and the opening and closing mechanism can control the leakage hole to close, and then open the water outlet trough. At this time, the mixed liquid will enter the interior of the water outlet pipe through the water outlet trough and be discharged. If the temperature does not meet the requirements, the opening and closing mechanism will control the leakage hole to open and close the water outlet trough. The mixed liquid will pass through the leakage hole into the next layer of the inclined cooling plate for continued cooling, thereby ensuring that the mixed liquid flowing out of the water outlet pipe meets the required temperature requirements.

[0011] Preferably, a driving motor is fixedly provided on the top of the cooling box, and the driving motor is transmission-connected to the top of the rotating rod, and the bottom end of the rotating rod passes through the circular through grooves on the L-shaped plate and the inclined cooling plate in sequence and is finally movably inserted into the bottom inner wall of the cooling box, and the edge of the rotating rod is located between the two groups of inclined cooling plates and is fixed with fan blades, and the inner wall of the cooling box is provided with heat dissipation holes, and the upper surface of the inclined cooling plate is located outside the circular through groove and is fixed with a protective sleeve.

[0012] During operation, the driving motor drives the rotating rod to rotate, and then drives the fan blades to rotate. The fan blades can blow air to cool the mixed liquid on the surface of the inclined cooling plate, and the heat dissipation holes play a role in heat dissipation.

[0013] Preferably, a movable sealing plate is provided at the bottom of the horizontal plate on the L-shaped plate, and the side of the movable sealing plate facing the drain hole is fixedly connected to the inner wall of the cooling box through a spring. An eccentric disk is fixedly provided on the rotating rod at the bottom of the horizontal plate of the L-shaped plate, and the rotating rod is located at the eccentric position of the eccentric disk.

[0014] During operation, when the driving motor drives the rotating rod to rotate, the rotating rod will drive the eccentric disc to rotate. Since the rotating rod is located at the eccentric position of the eccentric disc, when the eccentric disc rotates away from the edge of the rotating rod to a position close to the movable sealing plate, the movable sealing plate will move in the direction away from the rotating rod and seal the water hole. When the eccentric disc rotates close to the edge of the rotating rod to a position close to the movable sealing plate, the movable sealing plate will move in the direction close to the rotating rod under the action of the spring fixed thereto, and then open the water hole, thereby realizing the effect of intermittently opening the water hole, so that the mixed liquid flows down from the water hole intermittently, so as to ensure the cooling effect of the inclined cooling plate on the mixed liquid.

[0015] Preferably, a fixed heat conducting plate is fixed in the slot on the surface of the inclined cooling plate, the bottom end of the fixed heat conducting plate extends into the cold water chamber, a receiving groove is opened on the top of the fixed heat conducting plate, a movable heat conducting plate is slidably provided inside the storage groove, a limiting slider is fixedly provided at the bottom of the movable heat conducting plate, a sealing ring is fixedly provided at the upper port of the storage groove, a moving mechanism for controlling the upward and downward movement of the movable heat conducting plate is provided on the inclined cooling plate, and a sealing strip for sealing the gap between the movable heat conducting plate and the cooling box is fixedly provided on the front and rear side walls of the inclined cooling plate.

[0016] During operation, when the movable heat conduction plate is driven upward by the moving mechanism, the movable heat conduction plate can slow down the flow rate of the mixed liquid, thereby increasing the stop time of the mixed liquid on the surface of the inclined cooling plate and the heat exchange time, so that the inclined cooling plate has a better cooling effect on the mixed liquid. However, at the same time, the movable heat conduction plate will also cause part of the mixed liquid to be retained on the surface of the inclined cooling plate, and then the movable heat conduction plate can be driven to move downward intermittently by the moving mechanism to avoid the mixed liquid being retained between the movable heat conduction plate and the inclined cooling plate.

[0017] Preferably, the moving mechanism comprises a wedge block, a driving block, a driving rod and a sliding cavity; the sliding cavity is located inside the fixed heat conducting plate, a driving block is slidably arranged inside the sliding cavity, the bottom of the driving block is fixedly connected to the driving rod, the bottom end of the driving rod extends out of the bottom edge of the fixed heat conducting plate, the outside of the driving rod is located inside the sliding cavity and is sleeved with a spring, the spring is fixedly connected to the bottom of the driving block, the driving block and the movable heat conducting plate are both provided with magnets that attract each other, the bottom of the cold water cavity is provided with a wedge block that drives the driving rod to move up and down, one end of the wedge block close to the leakage hole is fixedly connected to the end of the cold water cavity by a spring, the wedge blocks are provided with several groups, and the several groups of wedge blocks are evenly distributed at the bottom of the cold water cavity, the inclined surfaces of the wedge blocks are away from the rotating rod, and the bottoms of the wedge blocks are fixedly provided with limiting sliders, the limiting sliders and the limiting sliding grooves at the bottom of the cold water cavity are slidably connected to each other, the several groups of wedge blocks are fixedly connected by connecting rods, and a group of wedge blocks close to the rotating rod is driven by the driving mechanism to move back and forth inside the cold water cavity.

[0018] During operation, when the driving mechanism drives the wedge block to move away from the leakage hole, the driving block will move downward under the action of the spring fixed thereto, and then the driving block will drive the movable heat conduction plate to move downward. When the driving mechanism drives the wedge block to move toward the leakage hole, the wedge block will push the bottom end of the driving rod to move upward, and then drive the driving block to move upward. The driving block will drive the movable heat conduction plate to move upward to slow down the mixed liquid.

[0019] Preferably, the driving mechanism includes a bending portion and a sleeve, the bending portion is located on the rotating rod, and the bending portion is located inside the cold water chamber, the bending portion is a U-shaped structure, and a sleeve is sleeved on the vertical rod of the bending portion. The edge of the sleeve is fixedly connected to one end of the pull rope, and the other end of the pull rope is fixedly connected to the wedge block close to the rotating rod.

[0020] During operation, the rotation of the rotating rod will drive the bending part to rotate, and the bending part will drive the sleeve to rotate. When the sleeve rotates to a position away from the wedge block, the pull rope fixedly connected to the sleeve will drive the wedge block to move in the direction away from the leakage hole. At this time, the driving block will move downward under the action of the spring fixedly connected to it, and when the bending part drives the sleeve to rotate to a position close to the wedge block, the group of wedge blocks close to the leakage hole will move in the direction close to the leakage hole under the action of the spring fixedly connected to it, thereby pushing the bottom end of the driving rod to move upward, thereby driving the driving block to move upward.

[0021] Preferably, a spring compression tube is fixedly provided at one end of the cold water chamber near the leakage hole, and a movable pressure plate is fixedly provided at one end of the spring compression tube away from the leakage hole. The movable pressure plate is fixedly connected to the top edge of the spring fixedly connected to the wedge block, and the movable pressure plate is located on the end of the spring near the wedge block. An air dividing cavity is provided inside the inclined cooling plate above the cold water chamber, and a blowing hole connected to the air dividing cavity is provided on the top of the inclined cooling plate. The end of the spring compression tube near the leakage hole is connected to the interior of the air dividing cavity through the air flow channel inside the inclined cooling plate, and the end of the spring compression tube near the leakage hole is also connected to the exhaust channel. The port of the exhaust channel is located at the bottom of the inclined cooling plate, and both the blowing hole and the exhaust channel are provided with one-way valves.

[0022] During operation, when the wedge block moves toward the leakage hole, the spring fixed to the wedge block will contract, causing the movable pressure plate to move toward the leakage hole and squeeze the spring compression tube. The gas inside the spring compression tube will enter the air distribution cavity and eventually be ejected from the blowing hole, which can further cool the mixed liquid on the surface of the inclined cooling plate, thereby accelerating the cooling rate. When the spring compression tube extends under the action of the movable pressure plate, the gas inside will enter the spring compression tube through the exhaust channel for storage.

[0023] Preferably, the opening and closing mechanism includes a sealing plug, a fixing plate, a sealing plate, a mounting groove and an electric push rod, the sealing plug is located below the leakage hole, the inner wall of the cooling box is located below the sealing plug and a fixing plate is fixedly provided thereon, the top of the fixing plate is fixedly connected to the bottom of the sealing plug through a spring, the mounting groove is located at the bottom of the water outlet groove, an electric push rod is fixedly provided at the bottom of the mounting groove, a sealing plate is fixedly provided on the top of the electric push rod, the bottom of the sealing plug is fixedly connected to one end of a pull rope, the other end of the pull rope passes through the bottom of the fixing plate and penetrates into the interior of the mounting groove and is fixedly connected to the bottom of the sealing plate.

[0024] During operation, the temperature sensor can monitor the temperature of the mixed liquid. When the temperature of the mixed liquid reaches the set value, the controller will receive the signal and control the electric push rod to start, which will drive the sealing plate to move down and open the water outlet. At the same time, the pull rope connected to the sealing plate becomes loose, and the sealing plug will move up under the action of the spring connected to it and seal the leakage hole, thereby preventing the mixed liquid that meets the temperature requirements from flowing from the leakage hole to the surface of the next inclined cooling plate. When the temperature of the mixed liquid passing through the temperature sensor does not meet the requirements, the controller will control the electric push rod to start and drive the sealing plate to move up to seal the water outlet. At this time, the sealing plate will drive the top end of the pull rope connected to the sealing plug to move up, and the bottom end of the pull rope will pull the sealing plug down and detach from the bottom of the leakage hole, thereby closing the water outlet and opening the leakage hole.

[0025] The technical effects and advantages of the present invention are as follows: 1. The process flow of the present invention removes most of the organic and inorganic impurities respectively through two steps of water extraction and salting out, and removes most of the acrylamide through alkaline solution washing, so that the mother liquor of the vacuum distillation contains only a small amount of impurities, no polymerization reaction occurs during the distillation process, and the product obtained after distillation is relatively pure, no recrystallization is required, the yield is stable, and it is good for the environment; 2. The present invention arranges a plurality of groups of inclined cooling plates inside the cooling box, so that the mixed liquid flows evenly from the drain holes at the bottom of the L-shaped plate and then flows through the surface of the inclined cooling plates from top to bottom in sequence, thereby increasing the spreading area of ​​the mixed liquid on the surface of the inclined cooling plates, thereby increasing the heat exchange effect, and then the mixed liquid can be quickly cooled down, which can greatly improve the production efficiency compared with direct natural cooling or the use of a fan cooling machine, thereby improving the economic benefits; 3. When the driving motor drives the rotating rod to rotate, the rotating rod will drive the eccentric disc to rotate. Since the rotating rod is located at the eccentric position of the eccentric disc, when the eccentric disc rotates away from the edge of the rotating rod to a position close to the movable sealing plate, the movable sealing plate will move in the direction away from the rotating rod and seal the water hole. When the eccentric disc rotates close to the edge of the rotating rod to a position close to the movable sealing plate, the movable sealing plate will move in the direction close to the rotating rod under the action of the spring fixed thereto, and then open the water hole, thereby realizing the effect of intermittently opening the water hole, so that the mixed liquid flows down from the water hole intermittently, so as to ensure the cooling effect of the inclined cooling plate on the mixed liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The figure is a diagram of the synthesis steps of diacetone acrylamide of the present invention.

[0027] Figure 2 It is a structural schematic diagram of the cooling device in the present invention.

[0028] Figure 3 It is a schematic diagram of the internal structure of the cooling plate of the present invention.

[0029] Figure 4 for Figure 3 Enlarged view of point A in the middle.

[0030] Figure 5 for Figure 3 Enlarged view of point B in the middle.

[0031] Figure 6 for Figure 3 Enlarged view of point C in the middle.

[0032] In the figure: cooling box 1, cold water circulation box 2, L-shaped plate 3, rotating rod 4, protective sleeve 5, inclined cooling plate 6, fan blade 7, blowing hole 8, movable heat conduction plate 9, liquid inlet pipe 10, cold water outlet pipe 11, cold water inlet pipe 12, water outlet pipe 13, water pump 14, water delivery cavity 15, cooling cavity 16, eccentric disc 17, movable sealing plate 18, water discharge hole 19, bending part 20, sleeve 21, limit slide groove 22, wedge block 2 3. Limit slider 24, spring compression tube 25, temperature sensor 26, movable pressure plate 27, magnet 28, drive block 29, air distribution cavity 30, drive rod 31, sliding cavity 32, storage groove 33, fixed heat conductive plate 34, sealing plug 35, fixed plate 36, water outlet groove 37, sealing plate 38, installation groove 39, electric push rod 40, heat dissipation hole 41, leakage hole 42, controller 43, sealing strip 45, leakage hole 42. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] The present invention provides Figure 1-6 The synthesis process of diacetone acrylamide shown in the figure comprises the following steps: S1: first adding concentrated sulfuric acid into a reaction kettle, then adding dropwise a mixture of acrylonitrile and diacetone alcohol while stirring, then raising the system temperature to 40-48°C, reacting for 4-4.5h to obtain a mixed solution; S2: cooling the mixed solution in S1 to 12-15°C through a cooling device, and then slowly adding the mixed solution to 25% ammonia water, controlling the temperature at 25-30°C during the liquid addition process, and adjusting the pH to 7.6-8 after the liquid addition is completed; S3: filtering the mixed solution in S2, adding distilled water to the filtrate, shaking it well, letting it stand and then separating the layers, and salting out the water layer with NaCl to separate the organic layer; S4: adding 15% NaOH solution to the organic layer, stirring it fully for 30-40min, lowering the temperature to 15-25°C through a cooling device again, and then letting it stand and separating the layers; S5: Add an inhibitor to the organic layer in S4, and then perform reduced pressure distillation under an absolute vacuum condition of 6 MPa, collect the distillate at a temperature of 120-130° C., and obtain diacetone acrylamide.

[0035] The process of the invention is simple, diacetone alcohol and acrylonitrile are synthesized in one step, the yield is high, and no solvents such as petroleum ether are used in the synthesis process, which is more environmentally friendly and has a high synthesis rate.

[0036] The molar ratio of acrylonitrile, diacetone alcohol and sulfuric acid is 1.2:0.25:2.0-2.5.

[0037] The cooling device includes a cooling box 1, an L-shaped plate 3 and an inclined cooling plate 6. The inclined cooling plate 6 is located inside the cooling box 1. The inclined cooling plate 6 is provided with a plurality of groups. The plurality of groups of inclined cooling plates 6 are arranged linearly and equidistantly from top to bottom inside the cooling box 1. The inclined cooling plates 6 of the upper layer are inclined in opposite directions to the inclined cooling plates 6 of the lower layer. A leakage hole 42 is provided at the bottom end of the inclined cooling plate 6. A water outlet trough 37 is provided at the inner wall of the cooling box 1 at the position at the bottom end of the inclined cooling plate 6. The water outlet trough 37 is located above the inclined cooling plate 6. An opening and closing mechanism for controlling the opening and closing of the leakage hole 42 and the water outlet trough 37 is provided in the cooling box 1. A temperature sensor 26 is fixed at a position near the bottom end of the upper surface of the inclined cooling plate 6. A temperature sensor 26 is fixed at a position on the outer wall of the cooling box 1 corresponding to the water outlet trough 37 located at the bottom. A water outlet pipe 13 is provided, and the water outlet pipe 13 is interconnected with several groups of water outlet grooves 37. A cold water chamber 16 is opened inside the inclined cooling plate 6, and the cold water chamber 16 is interconnected with a water delivery chamber 15 provided in the wall of the cooling box 1. The bottom end of the water delivery chamber 15 is interconnected with the cold water inlet pipe 12, and the bottom end of the cold water inlet pipe 12 is interconnected with the water pump 14 inside the cold water circulation box 2. The top of the water delivery chamber 15 is interconnected with the cold water outlet pipe 11, and the bottom end of the cold water outlet pipe 11 is inserted into the interior of the cold water circulation box 2. A liquid inlet pipe 10 is fixedly provided on the top side wall of the cooling box 1, an L-shaped plate 3 is fixedly provided on the top of the cooling box 1, and water discharge holes 19 are evenly opened on the bottom of the L-shaped plate 3. A controller 43 is fixedly provided on the inner wall of the cooling box 1, and the controller 43 is electrically connected to the temperature sensor 26 and the opening and closing mechanism.

[0038] During operation, the mixed liquid can be input into the cooling box 1 from the liquid inlet pipe 10, and the mixed liquid first enters the sealing area between the L-shaped plate 3 and the cooling box 1, and then the mixed liquid will leak evenly from the drain hole 19 at the bottom of the L-shaped plate 3, and then will fall on the surface of the inclined cooling plate 6 on the top layer, flow down along the surface of the inclined cooling plate 6, and leak again from the leakage hole 42 on the inclined cooling plate 6 to the surface of the next group of inclined cooling plates 6. Since the interior of the cold water chamber 16 is full of cold water, the surface temperature of the inclined cooling plate 6 is relatively low, and the mixed liquid passing through its surface can be cooled. The cold water circulation box 2, the cold water outlet pipe 11 and the cold water inlet pipe 12 can circulate the cold water inside the cold water chamber 16, so that the temperature of the water inside the cold water chamber 16 is always relatively low.

[0039] The present invention arranges a plurality of groups of inclined cooling plates 6 inside the cooling box 1, so that the mixed liquid flows down evenly from the drain hole 19 at the bottom of the L-shaped plate 3 and then flows through the surface of the inclined cooling plates 6 from top to bottom in sequence, thereby increasing the spreading area of ​​the mixed liquid on the surface of the inclined cooling plates 6, thereby increasing the heat exchange effect, and then the mixed liquid can be quickly cooled. Compared with direct natural cooling or using a fan cooling machine, this can greatly improve production efficiency and thus improve economic benefits.

[0040] In actual application, when the mixed liquid flows to the temperature sensor 26 at the bottom of the inclined cooling plate 6, the temperature sensor 26 can test the temperature of the mixed liquid. When the temperature meets the requirements, the controller will control the opening and closing mechanism to start, and the opening and closing mechanism can control the leakage hole 42 to close, and then open the water outlet groove 37. At this time, the mixed liquid will enter the interior of the water outlet pipe 13 through the water outlet groove 37 and be discharged. If the temperature does not meet the requirements, the opening and closing mechanism will control the leakage hole 42 to open and close the water outlet groove 37. The mixed liquid will pass through the leakage hole 42 to enter the next layer of the inclined cooling plate 6 for continued cooling, thereby ensuring that the mixed liquid flowing out of the water outlet pipe 13 meets the required temperature requirements.

[0041] A driving motor is fixedly provided on the top of the cooling box 1, and the driving motor is transmission-connected to the top of the rotating rod 4. The bottom end of the rotating rod 4 passes through the circular through grooves on the L-shaped plate 3 and the inclined cooling plate 6 in sequence and is finally movably inserted into the bottom inner wall of the cooling box 1. The edge of the rotating rod 4 is located between the two groups of inclined cooling plates 6 and is fixed with fan blades 7. The inner wall of the cooling box 1 is provided with heat dissipation holes 41, and the upper surface of the inclined cooling plate 6 is located outside the circular through groove and is fixed with a protective sleeve 5.

[0042] During operation, the driving motor drives the rotating rod 4 to rotate, and then drives the fan blades 7 to rotate. The fan blades 7 can blow air to cool the mixed liquid on the surface of the inclined cooling plate 6, and the heat dissipation holes 41 play a role in heat dissipation.

[0043] A movable sealing plate 18 is provided at the bottom of the horizontal plate on the L-shaped plate 3. The side of the movable sealing plate 18 facing the water hole 19 is fixedly connected to the inner wall of the cooling box 1 through a spring. An eccentric disk 17 is fixedly provided at the bottom of the horizontal plate of the L-shaped plate 3 on the rotating rod 4. The rotating rod 4 is located at the eccentric position of the eccentric disk 17.

[0044] During operation, when the driving motor drives the rotating rod 4 to rotate, the rotating rod 4 will drive the eccentric disc 17 to rotate. Since the rotating rod 4 is located at the eccentric position of the eccentric disc 17, when the eccentric disc 17 rotates away from the edge of the rotating rod 4 to a position close to the movable sealing plate 18, the movable sealing plate 18 will move in the direction away from the rotating rod 4 and seal the water hole 19. When the eccentric disc 17 rotates close to the edge of the rotating rod 4 to a position close to the movable sealing plate 18, the movable sealing plate 18 will move in the direction close to the rotating rod 4 under the action of the spring fixed thereto, and then open the water hole 19, thereby realizing the effect of intermittently opening the water hole 19, so that the mixed liquid flows down from the water hole 19 intermittently, so as to ensure the cooling effect of the inclined cooling plate 6 on the mixed liquid.

[0045] A fixed heat conducting plate 34 is fixed in the slot on the surface of the inclined cooling plate 6, and the bottom end of the fixed heat conducting plate 34 extends into the cold water chamber 16. A receiving groove 33 is opened on the top of the fixed heat conducting plate 34, and a movable heat conducting plate 9 is slidably provided inside the receiving groove 33. A limiting slider is fixed at the bottom of the movable heat conducting plate 9, and a sealing ring is fixed at the upper end of the receiving groove 33. A moving mechanism for controlling the upward and downward movement of the movable heat conducting plate 9 is provided on the inclined cooling plate 6, and a sealing strip 45 for sealing the gap between the movable heat conducting plate 9 and the cooling box 1 is fixed on the front and rear side walls of the inclined cooling plate 6.

[0046] During operation, when the movable heat conducting plate 9 is driven upward by the moving mechanism, the movable heat conducting plate 9 can slow down the flow rate of the mixed liquid, thereby increasing the stop time of the mixed liquid on the surface of the inclined cooling plate 6 and the heat exchange time, so that the inclined cooling plate 6 has a better cooling effect on the mixed liquid. However, at the same time, the movable heat conducting plate 9 will also cause part of the mixed liquid to be retained on the surface of the inclined cooling plate 6, and then the movable heat conducting plate 9 can be driven intermittently to move downward by the moving mechanism to avoid the mixed liquid from being retained between the movable heat conducting plate 9 and the inclined cooling plate 6.

[0047] The moving mechanism includes a wedge block 23, a driving block 29, a driving rod 31 and a sliding cavity 32; the sliding cavity 32 is located inside the fixed heat conducting plate 34, and a driving block 29 is slidably arranged inside the sliding cavity 32. The bottom of the driving block 29 is fixedly connected to the driving rod 31, and the bottom end of the driving rod 31 extends out of the bottom edge of the fixed heat conducting plate 34. The outside of the driving rod 31 is located inside the sliding cavity 32 and is sleeved with a spring, which is fixedly connected to the bottom of the driving block 29. The driving block 29 and the movable heat conducting plate 9 are both provided with magnets 28 that attract each other. The bottom of the cold water cavity 16 is provided with a spring that drives the driving rod 31 up and down. A movable wedge block 23, one end of the wedge block 23 close to the leakage hole 42 is fixedly connected to the end of the cold water chamber 16 through a spring, and the wedge block 23 is provided with several groups, and the several groups of wedge blocks 23 are evenly distributed at the bottom of the cold water chamber 16, the inclined surface of the wedge block 23 is away from the rotating rod 4, and the bottom of the wedge block 23 is fixedly provided with a limit slider 24, the limit slider 24 and the limit slide groove 22 at the bottom of the cold water chamber 16 are slidably connected to each other, and the several groups of wedge blocks 23 are fixedly connected by connecting rods, and a group of wedge blocks 23 close to the rotating rod 4 is driven by the driving mechanism to move back and forth inside the cold water chamber 16.

[0048] During operation, when the driving mechanism drives the wedge block 23 to move in the direction away from the leakage hole 42, the driving block 29 will move downward under the action of the spring fixed thereto, and then the driving block 29 will drive the movable heat conducting plate 9 to move downward. When the driving mechanism drives the wedge block 23 to move in the direction close to the leakage hole 42, the wedge block 23 will push the bottom end of the driving rod 31 to move upward, and then drive the driving block 29 to move upward. The driving block 29 will drive the movable heat conducting plate 9 to move upward to slow down the mixed liquid.

[0049] The driving mechanism includes a bending portion 20 and a sleeve 21. The bending portion 20 is located on the rotating rod 4 and inside the cold water chamber 16. The bending portion 20 is a U-shaped structure. A sleeve 21 is sleeved on the vertical rod of the bending portion 20. The edge of the sleeve 21 is fixedly connected to one end of the pull rope, and the other end of the pull rope is fixedly connected to a wedge block 23 close to the rotating rod 4.

[0050] During operation, the rotation of the rotating rod 4 will drive the bending portion 20 to rotate, and the bending portion 20 will drive the sleeve 21 to rotate. When the sleeve 21 rotates to a position away from the wedge block 23, the pull rope fixedly connected to the sleeve 21 will drive the wedge block 23 to move in the direction away from the leakage hole 42. At this time, the driving block 29 will move downward under the action of the spring fixed thereto. When the bending portion 20 drives the sleeve 21 to rotate to a position close to the wedge block 23, the group of wedge blocks 23 close to the leakage hole 42 will move in the direction close to the leakage hole 42 under the action of the spring fixed thereto, thereby pushing the bottom end of the driving rod 31 to move upward, thereby driving the driving block 29 to move upward.

[0051] A spring compression tube 25 is fixedly provided at one end of the cold water chamber 16 close to the leakage hole 42, and a movable pressure plate 27 is fixedly provided at one end of the spring compression tube 25 away from the leakage hole 42. The movable pressure plate 27 is fixedly connected to the top edge of the spring fixedly connected to the wedge block 23, and the movable pressure plate 27 is located on the end of the spring close to the wedge block 23. An air dividing chamber 30 is provided inside the inclined cooling plate 6 above the cold water chamber 16, and a blowing hole 8 communicating with the air dividing chamber 30 is provided on the top of the inclined cooling plate 6. The end of the spring compression tube 25 close to the leakage hole 42 is communicated with the interior of the air dividing chamber 30 through the air flow channel inside the inclined cooling plate 6, and the end of the spring compression tube 25 close to the leakage hole 42 is also communicated with the exhaust channel 46. The port of the exhaust channel 46 is located at the bottom of the inclined cooling plate 6, and both the blowing hole 8 and the exhaust channel 46 are provided with a one-way valve.

[0052] During operation, when the wedge block 23 moves toward the direction close to the leakage hole 42, the spring fixed to the wedge block 23 will shrink, thereby causing the movable pressure plate 27 to move toward the direction close to the leakage hole 42 and squeeze the spring compression tube 25, and the gas inside the spring compression tube 25 will enter the interior of the gas distribution cavity 30 and eventually be ejected from the blowing hole 8, which can further cool the mixed liquid on the surface of the inclined cooling plate 6, thereby accelerating the cooling rate, and when the spring compression tube 25 extends under the action of the movable pressure plate 27, the gas inside 1 will enter the interior of the spring compression tube 25 through the exhaust channel 46 for storage.

[0053] The opening and closing mechanism includes a sealing plug 35, a fixing plate 36, a sealing plate 38, a mounting groove 39 and an electric push rod 40. The sealing plug 35 is located below the leakage hole 42. The inner wall of the cooling box 1 is located below the sealing plug 35 and is fixedly provided with a fixing plate 36. The top of the fixing plate 36 is fixedly connected to the bottom of the sealing plug 35 through a spring. The mounting groove 39 is located at the bottom of the water outlet groove 37. The bottom of the mounting groove 39 is fixedly provided with an electric push rod 40. The top of the electric push rod 40 is fixedly provided with a sealing plate 38. The bottom of the sealing plug 35 is fixedly connected to one end of a pull rope, and the other end of the pull rope passes through the bottom of the fixing plate 36 and penetrates into the interior of the mounting groove 39 and is fixedly connected to the bottom of the sealing plate 38.

[0054] During operation, the temperature sensor 26 can monitor the temperature of the mixed liquid. When the temperature of the mixed liquid reaches the set value, the controller 43 will receive the signal and control the electric push rod 40 to start. The electric push rod 40 will drive the sealing plate 38 to move down and open the water outlet trough 37. At the same time, the pull rope fixedly connected to the sealing plate 38 becomes loose, and the sealing plug 35 will move up under the action of the spring fixed thereto and seal the leakage hole 42, thereby preventing the mixed liquid that meets the temperature requirement from flowing from the leakage hole 42 to the surface of the next inclined cooling plate 6. When the temperature of the mixed liquid passing through the temperature sensor 26 does not meet the requirement, the controller 43 will control the electric push rod 43 to start and drive the sealing plate 38 to move up to seal the water outlet trough 37. At this time, the sealing plate 38 will drive the top end of the pull rope fixedly connected to the sealing plug 35 to move up, and the bottom end of the pull rope will pull the sealing plug 35 down and detach from the bottom of the leakage hole 42, thereby closing the water outlet trough 37 and opening the leakage hole 42.

[0055] Working principle: The process flow of the present invention removes most of the organic and inorganic impurities through two steps of water extraction and salting out, and removes most of the acrylamide through alkali solution washing, so that the mother liquor of vacuum distillation contains only a small amount of impurities, no polymerization reaction occurs during the distillation process, and the product obtained after distillation is relatively pure, no recrystallization is required, the yield is stable, and it is good for the environment.

[0056] During operation, the mixed liquid can be input into the cooling box 1 from the liquid inlet pipe 10, and the mixed liquid first enters the sealing area between the L-shaped plate 3 and the cooling box 1, and then the mixed liquid will leak evenly from the drain hole 19 at the bottom of the L-shaped plate 3, and then will fall on the surface of the inclined cooling plate 6 on the top layer, flow down along the surface of the inclined cooling plate 6, and leak again from the leakage hole 42 on the inclined cooling plate 6 to the surface of the next group of inclined cooling plates 6. Since the interior of the cold water chamber 16 is full of cold water, the surface temperature of the inclined cooling plate 6 is relatively low, and the mixed liquid passing through its surface can be cooled. The cold water circulation box 2, the cold water outlet pipe 11 and the cold water inlet pipe 12 can circulate the cold water inside the cold water chamber 16, so that the temperature of the water inside the cold water chamber 16 is always relatively low.

[0057] At the same time, the present invention arranges several groups of inclined cooling plates 6 inside the cooling box 1, so that the mixed liquid flows down evenly from the water drain hole 19 at the bottom of the L-shaped plate 3 and then flows through the surface of the inclined cooling plate 6 from top to bottom in sequence, thereby increasing the spreading area of ​​the mixed liquid on the surface of the inclined cooling plate 6, thereby increasing the heat exchange effect, and then the mixed liquid can be quickly cooled down. Compared with direct natural cooling or using a fan cooling machine, this can greatly improve production efficiency and thus improve economic benefits.

Claims

1. A process for synthesizing diacetone acrylamide, characterized in that: The steps include: S1: first add concentrated sulfuric acid into a reaction kettle, then dropwise add a mixture of acrylonitrile and diacetone alcohol while stirring, then raise the system temperature to 40-48°C, and react for 4-4.5h to obtain a mixed solution; S2: The mixed liquid in S1 is cooled to 12-15°C by a cooling device, and then the mixed liquid is slowly added to 25% ammonia water. The temperature is controlled at 25-30°C during the addition process. After the addition is completed, the pH is adjusted to 7.6-8; S3: Filter the mixed liquid in S2, add distilled water to the filtrate, shake well, let stand and separate into layers, and separate the organic layer by salting out the aqueous layer with NaCl; S4: Add 15% NaOH solution to the organic layer, stir thoroughly for 30-40 minutes, lower the temperature to 15-25°C through a cooling device again, and then stand to separate the layers; S5: adding a polymerization inhibitor to the organic layer in S4, and then performing reduced pressure distillation under an absolute vacuum condition of 666 Pa, collecting a distillate at a temperature of 120-130° C., and obtaining diacetone acrylamide; The molar ratio of acrylonitrile, diacetone alcohol and sulfuric acid is 1.2:0.25:2.0-2.5; The cooling device comprises a cooling box (1), an L-shaped plate (3) and an inclined cooling plate (6), wherein the inclined cooling plate (6) is located inside the cooling box (1), and a plurality of groups of inclined cooling plates (6) are provided. The plurality of groups of inclined cooling plates (6) are arranged linearly from top to bottom in an equidistant manner inside the cooling box (1), and the inclined cooling plates (6) of the upper layer are inclined in opposite directions to the inclined cooling plates (6) of the lower layer. A liquid leakage hole (42) is provided at the bottom end of the inclined cooling plate (6). The inner wall of the cooling box (1) is provided with a water outlet groove (37) at a position located at the bottom end of the inclined cooling plate (6), and the water outlet groove (37) is located above the inclined cooling plate (6). An opening and closing mechanism for controlling the opening and closing of the leakage hole (42) and the water outlet groove (37) is provided in the cooling box (1). A temperature sensor (26) is fixed at a position near the bottom end of the upper surface of the inclined cooling plate (6), and a temperature sensor (26) is fixed at a position on the outer wall of the cooling box (1) corresponding to the water outlet groove (37) located at the bottom. A water outlet pipe (13) is provided, and the water outlet pipe (13) and a plurality of water outlet grooves (37) are interconnected. A cold water chamber (16) is provided inside the inclined cooling plate (6). The cold water chamber (16) is interconnected with a water delivery chamber (15) provided in the wall of the cooling box (1). The bottom end of the water delivery chamber (15) is interconnected with a cold water inlet pipe (12). The bottom end of the cold water inlet pipe (12) is interconnected with a water pump (14) inside the cold water circulation box (2). The water delivery chamber (15) The top end of the cooling box (1) is connected to the cold water outlet pipe (11), the bottom end of the cold water outlet pipe (11) is inserted into the interior of the cold water circulation box (2), a liquid inlet pipe (10) is fixedly provided on the top side wall of the cooling box (1), an L-shaped plate (3) is fixedly provided on the top of the cooling box (1), and water discharge holes (19) are evenly provided on the bottom of the L-shaped plate (3), a controller (43) is fixedly provided on the inner wall of the cooling box (1), and the controller (43) is electrically connected to the temperature sensor (26) and the opening and closing mechanism.

2. A process for synthesizing diacetone acrylamide according to claim 1, characterized in that: A driving motor is fixedly provided on the top of the cooling box (1), and the driving motor is transmission-connected to the top of the rotating rod (4). The bottom end of the rotating rod (4) passes through the circular through slots on the L-shaped plate (3) and the inclined cooling plate (6) in sequence and is finally movably inserted into the bottom inner wall of the cooling box (1). The edge of the rotating rod (4) is located between the two groups of inclined cooling plates (6) and is fixedly provided with fan blades (7). The inner wall of the cooling box (1) is provided with heat dissipation holes (41), and the upper surface of the inclined cooling plate (6) is located outside the circular through slot and is fixedly provided with a protective sleeve (5).

3. A process for synthesizing diacetone acrylamide according to claim 2, characterized in that: A movable sealing plate (18) is provided at the bottom of the horizontal plate on the L-shaped plate (3); a side of the movable sealing plate (18) facing the water hole (19) is fixedly connected to the inner wall of the cooling box (1) via a spring; an eccentric disc (17) is fixedly provided on the rotating rod (4) at the bottom of the horizontal plate on the L-shaped plate (3); the rotating rod (4) is located at an eccentric position of the eccentric disc (17).

4. A process for synthesizing diacetone acrylamide according to claim 3, characterized in that: A fixed heat conducting plate (34) is fixedly arranged in a slot on the surface of the inclined cooling plate (6), the bottom end of the fixed heat conducting plate (34) extends into the interior of the cold water chamber (16), a receiving groove (33) is provided on the top of the fixed heat conducting plate (34), a movable heat conducting plate (9) is slidably arranged inside the receiving groove (33), a limit slider is fixedly arranged at the bottom of the movable heat conducting plate (9), a sealing ring is fixedly arranged at the upper end of the receiving groove (33), a moving mechanism for controlling the upward and downward movement of the movable heat conducting plate (9) is provided on the inclined cooling plate (6), and a sealing strip (45) for sealing the gap between the movable heat conducting plate (9) and the cooling box (1) is fixedly arranged on the front and rear side walls of the inclined cooling plate (6).

5. A process for synthesizing diacetone acrylamide according to claim 4, characterized in that: The moving mechanism comprises a wedge block (23), a driving block (29), a driving rod (31) and a sliding cavity (32); the sliding cavity (32) is located inside the fixed heat conducting plate (34); a driving block (29) is slidably arranged inside the sliding cavity (32); the bottom of the driving block (29) is fixedly connected to the driving rod (31); the bottom end of the driving rod (31) extends out of the bottom edge of the fixed heat conducting plate (34); the outside of the driving rod (31) is located inside the sliding cavity (32) and is sleeved with a spring; the spring is fixedly connected to the bottom of the driving block (29); the insides of the driving block (29) and the movable heat conducting plate (9) are both provided with magnets (28) that attract each other; the bottom of the cold water cavity (16) is provided with a spring that drives the driving block (29); A wedge block (23) is moved up and down by the moving rod (31), one end of the wedge block (23) close to the leakage hole (42) is fixedly connected to the end of the cold water chamber (16) through a spring, a plurality of groups of wedge blocks (23) are provided, and the plurality of groups of wedge blocks (23) are evenly distributed at the bottom of the cold water chamber (16), the inclined surface of the wedge block (23) is away from the rotating rod (4), and a limiting slider (24) is fixedly provided at the bottom of the wedge block (23), the limiting slider (24) and the limiting slide groove (22) at the bottom of the cold water chamber (16) are slidably connected to each other, and the plurality of groups of wedge blocks (23) are fixedly connected by connecting rods, and a group of wedge blocks (23) close to the rotating rod (4) is driven by a driving mechanism to move back and forth inside the cold water chamber (16).

6. A process for synthesizing diacetone acrylamide according to claim 5, characterized in that: The driving mechanism comprises a bending portion (20) and a sleeve (21); the bending portion (20) is located on the rotating rod (4), and the bending portion (20) is located inside the cold water chamber (16); the bending portion (20) is a U-shaped structure; a sleeve (21) is sleeved on a vertical rod of the bending portion (20); an edge of the sleeve (21) is fixedly connected to one end of a pull rope, and the other end of the pull rope is fixedly connected to a wedge block (23) close to the rotating rod (4).

7. A process for synthesizing diacetone acrylamide according to claim 6, characterized in that: A spring compression tube (25) is fixedly provided at one end of the cold water chamber (16) close to the liquid leakage hole (42), and a movable pressure plate (27) is fixedly provided at one end of the spring compression tube (25) away from the liquid leakage hole (42). The movable pressure plate (27) is fixedly connected to the top edge of the spring fixedly connected to the wedge block (23), and the movable pressure plate (27) is located on the end of the spring close to the wedge block (23). An air dividing cavity (30) is opened inside the inclined cooling plate (6) located above the cold water chamber (16). The inclined cooling plate ( A blowing hole (8) communicating with the air dividing cavity (30) is provided at the top of the inclined cooling plate (6); one end of the spring compression tube (25) close to the leakage hole (42) is communicated with the interior of the air dividing cavity (30) through the air flow channel inside the inclined cooling plate (6); and one end of the spring compression tube (25) close to the leakage hole (42) is also communicated with the exhaust channel (46); a port of the exhaust channel (46) is located at the bottom of the inclined cooling plate (6); and one-way valves are provided inside the blowing hole (8) and the exhaust channel (46).

8. A process for synthesizing diacetone acrylamide according to claim 7, characterized in that: The opening and closing mechanism comprises a sealing plug (35), a fixing plate (36), a sealing plate (38), a mounting groove (39) and an electric push rod (40); the sealing plug (35) is located below the liquid leakage hole (42); the inner wall of the cooling box (1) is located below the sealing plug (35) and is fixedly provided with a fixing plate (36); the top of the fixing plate (36) is fixedly connected to the bottom of the sealing plug (35) via a spring; the mounting groove (39) is located at the bottom of the water outlet groove (37); the bottom of the mounting groove (39) is fixedly provided with an electric push rod (40); the top of the electric push rod (40) is fixedly provided with a sealing plate (38); the bottom of the sealing plug (35) is fixedly connected to one end of a pull rope; the other end of the pull rope passes through the bottom of the fixing plate (36) and enters the interior of the mounting groove (39) to be fixedly connected to the bottom of the sealing plate (38).

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