Semi-continuous production process of polyester resin for powder coating

Abstract

The invention relates to the technical field of polyester resin production, in particular to a semi-continuous production process of polyester resin for powder coating, which comprises raw material conveying, raw material premixing, esterification reaction, material transfer and polymerization reaction. Through cooperative operation of the raw material conveying frame, the pre-reaction rotating shaft and the pre-reaction material mixing frame and cooperation of the conveying cavity, the material distributing frame and the material distributing partition plate, raw materials are circularly conveyed and preheated in the conveying cavity, the oppositely-arranged discharging openings spray liquid raw materials in a mist spraying mode, powder raw materials are conveyed in a dispersed mode, the raw material contact area is greatly increased, and the premixing effect is greatly improved; a pre-reaction rotating shaft drives a pre-reaction material mixing frame to rotate to further strengthen premixing, an electric heating element and a temperature sensor accurately control the temperature, and it is guaranteed that the pre-reaction temperature is stable; according to the overall design, the raw material premixing effect, the reaction temperature accuracy and the material mixing uniformity in semi-continuous production of polyester resin are comprehensively improved from raw material conveying, premixing and temperature control to material transferring and mixing.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polyester resin production, in particular to a semi-continuous production process of polyester resin for powder coating. BACKGROUND

[0002] As a typical representative of environmentally friendly coatings, powder coating has been increasingly widely used in the fields of automobiles, household appliances, buildings, etc. due to its zero VOC emission and excellent coating performance. As the core film-forming material of powder coating, the quality of polyester resin directly determines the key performance of powder coating such as adhesion, hardness, weather resistance, etc. In the production process of polyester resin, semi-continuous production process has become one of the mainstream choices in the industry due to its consideration of production flexibility and efficiency. However, with the growing demand for high-quality and high-performance polyester resin in the market, the limitations of traditional semi-continuous production process have gradually become apparent.

[0003] Currently, in the semi-continuous production process of polyester resin for powder coating, the premixing effect of powder raw materials and liquid raw materials is not good in the traditional process, which leads to insufficient contact of materials at the beginning of the reaction, affecting the esterification reaction rate and uniformity. In the reaction control link, the stirring system is difficult to dynamically adjust according to the reaction process, which is prone to local over-reaction or under-reaction, and the control precision of parameters such as reaction temperature and pressure is limited, resulting in large quality fluctuations between product batches. In terms of heat management, the heat energy in the reaction process is not effectively recycled, and the preheating and cooling efficiency is low, which not only wastes energy but also increases production costs.

[0004] Therefore, we propose a semi-continuous production process of polyester resin for powder coating. SUMMARY

[0005] In view of the shortcomings of the prior art, the present application provides a semi-continuous production process of polyester resin for powder coating to solve the above technical defects.

[0006] To achieve the above purpose, the present application is implemented by the following technical scheme: a semi-continuous production process of polyester resin for powder coating, comprising the following steps:

[0007] Step one, raw material conveying: after the powder raw materials are dispersed and impurity-removed, they are quantitatively fed into the interior of the reaction main body according to the formula process requirements, and at the same time, the liquid raw materials are quantitatively conveyed into the interior of the reaction main body by a metering pump according to the formula process requirements;

[0008] Step two, raw material premixing: in the interior of the reaction main body, the powder raw materials and the liquid raw materials are preliminarily mixed in the interior of the pre-reaction kettle body by a premixing unit, and at the same time, the heating system in the interior of the pre-reaction kettle body is started, gradually warming the mixed raw materials from room temperature to the temperature specified in the formula process;

[0009] Step three, esterification reaction: the water generated in the pre-reaction kettle body is escaped in the form of steam, which is recycled through the condenser connected with the pre-reaction kettle body; constant temperature stirring is carried out in the pre-reaction kettle body to continuously carry out esterification reaction until the acid value is reduced to the target range specified in the formula process;

[0010] Step four, material transfer: the heat exchange unit in the pre-reaction kettle body is used to cool the material in the pre-reaction process, and the heat energy in the pre-reaction process is replaced and sent out; after the material is cooled to the temperature specified in the formula process, it is sent into the inside of the reaction kettle body for the next step reaction;

[0011] Step five, polymerization reaction: monomers and reaction aids are added in the inside of the reaction kettle body, and stirring and mixing are carried out in the inside of the reaction kettle body, and at the same time, the vacuum system is started to keep the inside of the reaction kettle body at a set vacuum degree; constant temperature is maintained in the inside of the reaction kettle body, and under vacuum, polycondensation is carried out to make the molecular chain grow until the hydroxyl value reaches the process requirement; vacuum is maintained to remove small molecules to promote the forward progress of polycondensation; finally, the heat in the inside of the reaction kettle body is replaced by the heat exchange unit to cool the inside of the reaction kettle body to 180-200℃, the vacuum system is closed, nitrogen is introduced into the inside of the reaction kettle body to break the vacuum, the gear pump is matched with the melt filter to deliver the polyester melt to the underwater pelletizer, and the polyester melt is cooled and solidified into particles to complete the semi-continuous production of the polyester resin.

[0012] Preferably, the reaction main body is composed of a pre-reaction kettle body, a reaction kettle body and a kettle body sealing cover, the top of the reaction kettle body is sealingly connected with the pre-reaction kettle body through a connecting flange, and the top of the pre-reaction kettle body is further sealingly connected with the kettle body sealing cover through a bolt; a material separation frame is further fixedly arranged in the inside of the pre-reaction kettle body, a plurality of material guiding holes are arranged in the inside of the material separation frame, the inside of each material guiding hole is in communication with the inside of the pre-reaction kettle body and the reaction kettle body, and an automatic control valve is further arranged in the inside of each material guiding hole.

[0013] Preferably, the material guiding hole is designed in the shape of a truncated cone, the upper end diameter of the material guiding hole is larger than the lower end diameter, and a plurality of turbulence strips are further arranged on the inner wall of the material guiding hole.

[0014] Preferably, a premixing unit for initial mixing of powder raw materials and liquid raw materials is arranged in the inside of the pre-reaction kettle body, the premixing unit comprises a raw material conveying frame, a pre-reaction rotating shaft and a pre-reaction mixing frame, a raw material conveying frame is fixedly arranged on the top of the inner wall of the kettle body sealing cover and above the inside of the pre-reaction kettle body, a conveying cavity is arranged in the inside of each raw material conveying frame, a pre-reaction rotating shaft is rotatably arranged in the inside of the pre-reaction kettle body, a pre-reaction mixing frame is fixedly arranged on the outer circumferential surface of the pre-reaction rotating shaft, a reaction control servo motor is fixedly arranged on the top of the kettle body sealing cover, and the output shaft bottom end of the reaction control servo motor is fixedly connected with the top end of the pre-reaction rotating shaft through a connecting shaft.

[0015] Preferably, the pre-reaction rotating shaft is fixed with a material distribution frame above and below, and the circumference of the material distribution frame is in sealing sliding connection with the inside of the conveying cavity.

[0016] Preferably, the inside of the reaction kettle body is provided with a reaction unit, the reaction unit comprises a reaction transmission frame and a mixing stirring shaft, the bottom of the material distribution frame is fixed with the reaction transmission frame, and the bottom end of the pre-reaction rotating shaft extends into the inside of the reaction transmission frame, a driving gear is rotationally arranged above the inside of the reaction transmission frame, and the bottom end of the pre-reaction rotating shaft is fixedly connected with the inside of the driving gear; three transmission gears are further rotationally arranged on the top of the inner wall of the reaction transmission frame, and the tooth surfaces of the three transmission gears are in meshing transmission with the tooth surfaces of the driving gear; an inner tooth ring is further rotationally arranged in the middle of the inside of the reaction transmission frame, and the tooth surfaces of the three transmission gears are in meshing transmission with the inner tooth surfaces of the inner tooth ring; the bottom of the inner tooth ring is fixed with the mixing stirring shaft, and the bottom end of the mixing stirring shaft extends below the reaction transmission frame.

[0017] Preferably, the surface of the mixing stirring shaft is further provided with a plurality of air guide holes, the inside of the reaction transmission frame is further fixed with an air guide ring below, and one side of the air guide ring is fixed with a pneumatic pump; the inside of the air guide ring is provided with an air guide flow channel, and the inside of the air guide flow channel is in communication with the inside of the plurality of air guide holes.

[0018] Preferably, the surface of the mixing stirring shaft below the reaction transmission frame is fixed with a flat paddle, an inclined paddle and an anchor paddle from top to bottom respectively; the inside of the mixing stirring shaft is provided with a circulating feed port, and the bottom end of the circulating feed port penetrates the bottom of the mixing stirring shaft, the top end of the circulating feed port is in communication with the inside of the plurality of air guide holes, and the inside of the flat paddle is further provided with a circulating discharge port, and the inside of the circulating discharge port is in communication with the inside of the circulating feed port.

[0019] Preferably, the inside of the pre-reaction kettle body and the reaction kettle body is provided with a heat exchange unit; the heat exchange unit comprises a heat exchange bushing, the inside of the pre-reaction kettle body and the reaction kettle body is fixed with a heat exchange bushing, the inside of the pre-reaction kettle body and the reaction kettle body is fixed with a spiral flow guide frame between the inner wall of the pre-reaction kettle body and the outside of the heat exchange bushing, and the inside of the two heat exchange bushings is provided with a spiral heat exchange flow channel.

[0020] Preferably, the upper and lower parts of the inside of the two spiral heat exchange channels are provided with circulating heat exchange interfaces, the upper and lower parts of the inside of the spiral guide frame of the pre-reaction kettle body and the reaction kettle body are provided with circulating material guide interfaces, and the inside of the spiral guide frame of the pre-reaction kettle body and the reaction kettle body is communicated through an automatic control valve; the inside of the pre-reaction kettle body and the reaction kettle body is also communicated with a vacuum system, and the inside of the pre-reaction kettle body is also communicated with a condensing system; the bottom of the reaction kettle body is provided with a discharge pipe.

[0021] Compared with the prior art, the following beneficial effects are achieved:

[0022] 1. By accurately quantitatively feeding the powder raw materials and conveying the liquid raw materials in step one, the accuracy of the raw material ratio is ensured, laying the foundation for stable production; in step two, the pre-mixing unit is used to preliminarily mix and heat in the pre-reaction kettle body, promote the preliminary reaction of the raw materials, and improve the reaction efficiency; in step three, the condenser is used to recover water vapor, realize the rational use of water resources, and the micro-positive pressure and online monitoring of the water discharge rate are used to accurately control the esterification process; in step four, the stirring speed is adapted according to the viscosity to ensure uniform and sufficient reaction, which is beneficial to the stable acid value; in step five, the heat exchange unit realizes cooling and heat energy replacement, saves energy and avoids material solidification, and the preheating of the reaction kettle body ensures the continuity of production; in step six, the material is supplemented, the temperature is accurately controlled, and the vacuum operation is performed, which promotes the growth of molecular chains and the removal of small molecules, improves the product quality, and efficiently completes the production by underwater cutting, the overall scheme improves the production efficiency and product quality, realizes energy saving and rational use of resources, and the structures cooperate to ensure the stable and efficient operation of the process, and promote the progress of the semi-continuous production technology of polyester resin for powder coatings.

[0023] 2. The reaction body in the application is composed of a pre-reaction kettle body, a reaction kettle body and a kettle body sealing cover, which guarantees the sealing and stability of the reaction system; the material separation frame, the conical frustum and the material guide hole with a spoiler strip in the pre-reaction kettle body can further mix the materials when they pass through during the communication or separation of the pre-reaction kettle body and the reaction kettle body, and improve the uniformity of the materials. In the pre-mixing unit, the raw material conveying frame, the pre-reaction rotating shaft and the pre-reaction mixing frame cooperate, the conveying cavity, the material distribution frame and the material distribution partition cooperate to make the raw materials circulate and preheat in the conveying cavity, the oppositely arranged discharge ports spray liquid raw materials in the form of mist and disperse powder raw materials, which greatly improves the contact area and pre-mixing effect of the raw materials, the pre-reaction rotating shaft drives the pre-reaction mixing frame to rotate to further strengthen the pre-mixing, the electric heating element and the temperature sensor accurately control the temperature to ensure the stability of the pre-reaction temperature. The overall design improves the raw material pre-mixing effect, reaction temperature accuracy and material mixing uniformity in the semi-continuous production of polyester resin from raw material conveying, pre-mixing, temperature control to material transfer and mixing, lays a foundation for the subsequent esterification and polycondensation reaction, promotes the improvement of production efficiency and product quality, and the structures cooperate with each other to build an efficient, accurate and stable production system.

[0024] 3, The reaction unit of the present application, the reaction transmission frame, the mixing stirring shaft and other components cooperate, the pre-reaction rotating shaft drives the driving gear, the driving gear is meshed and driven through the transmission gear and the internal gear ring, the internal gear ring and the driving gear rotate synchronously but at different speeds, which meets the different speed requirements of the pre-reaction kettle body and the reaction kettle body for pre-mixing and reaction of materials. The flat paddle, inclined paddle and anchor paddle on the surface of the mixing stirring shaft have clear division of labor. The flat paddle pushes the material to circulate axially, solving the problem of upper layering. The inclined paddle generates radial vortex and shear force to scatter the material and break the agglomerated particles. The anchor paddle sweeps the dead zone at the bottom of the kettle to prevent material deposition and overheating. At the same time, the mixing stirring shaft, the internal circulation feeding port, the air guide hole and the air guide ring cooperate with the plunger type pneumatic pump to assist material mixing and reaction environment control. The sealing ring ensures the sealing of the air guide system and the flexibility of the stirring shaft rotation. The reaction unit, the reaction transmission frame, the mixing stirring shaft, the driving gear, the transmission gear, the internal gear ring, the flat paddle, the inclined paddle, the anchor paddle, the circulation feeding port, the circulation discharge port and the air guide ring cooperate with each other to greatly improve the uniformity of material mixing in the reaction kettle body, the reaction stability, optimize the stirring effect, provide an efficient and adaptive reaction environment for polyester resin synthesis, and help improve production efficiency and product quality.

[0025] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application, and the purposes and other advantages of the present application can be achieved and obtained by the structures indicated in the specification and drawings. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The flow chart of the semi-continuous production process of the polyester resin for powder coating according to the embodiment of the present application is shown in the figure.

[0027] Figure 2 The schematic diagram of the reaction main body structure according to the embodiment of the present application is shown in the figure.

[0028] Figure 3 The exploded view of the reaction main body structure according to the embodiment of the present application is shown in the figure.

[0029] Figure 4 The schematic diagram of the internal structure of the kettle body sealing cover according to the embodiment of the present application is shown in the figure.

[0030] Figure 5 The schematic diagram of the raw material conveying frame and the material distribution frame structure according to the embodiment of the present application is shown in the figure.

[0031] Figure 6 The schematic diagram of the internal structure of the pre-reaction kettle body according to the embodiment of the present application is shown in the figure.

[0032] Figure 7 The schematic diagram of the internal structure of the pre-reaction kettle body and the reaction kettle body according to the embodiment of the present application is shown in the figure.

[0033] Figure 8It is a schematic view of the reaction kettle body and the spiral flow guide frame structure of the embodiment of the present application.

[0034] Figure 9 It is a schematic view of the mixing stirring shaft and the reaction transmission frame structure of the embodiment of the present application.

[0035] Figure 10 It is a schematic view of the reaction transmission frame and the inner tooth ring structure of the embodiment of the present application.

[0036] Figure 11 It is a schematic view of the heat exchange bushing and the spiral heat exchange flow channel structure of the embodiment of the present application.

[0037] In the figure, 1 is a reaction main body; 2 is a pre-reaction kettle body; 3 is a reaction kettle body; 4 is a kettle body sealing cover; 5 is a pre-mixing unit; 6 is a reaction unit; 7 is a heat exchange unit; 8 is a material separation frame; 9 is a material guide hole; 10 is a raw material conveying frame; 11 is a discharge port; 12 is a conveying cavity; 13 is a material distribution frame; 14 is a material distribution partition plate; 15 is a reaction control servo motor; 16 is a pre-reaction rotating shaft; 17 is a pre-reaction mixing frame; 18 is a reaction transmission frame; 19 is a mixing stirring shaft; 20 is a driving gear; 21 is a transmission gear; 22 is an inner tooth ring; 23 is a flat paddle; 24 is an inclined paddle; 25 is an anchor paddle; 26 is a circulating feed port; 27 is a circulating discharge port; 28 is a gas guide ring; 29 is a heat exchange bushing; 30 is a spiral flow guide frame; and 31 is a spiral heat exchange flow channel. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0039] Embodiment 1

[0040] Please refer to Figures 1 to 11 As shown in the figure, the semi-continuous production process of the polyester resin for powder coating comprises the following steps:

[0041] Step one, raw material conveying: the powder raw material after dispersion and impurity removal treatment is quantitatively fed into the inside of the reaction main body 1 according to the formula process requirement, and the liquid raw material is quantitatively conveyed into the inside of the reaction main body 1 by a metering pump according to the formula process requirement;

[0042] Step two, raw material pre-mixing: in the inside of the reaction main body 1, the powder raw material and the liquid raw material are preliminarily mixed in the inside of the pre-reaction kettle body 2 by the pre-mixing unit 5, and at the same time, the heating system in the inside of the pre-reaction kettle body 2 is started to gradually heat the mixed raw material from room temperature to the temperature specified in the formula process.

[0043] Step three, esterification reaction: the water produced in the pre-reaction kettle 2 is in the form of steam, which is recovered by the condenser connected with the pre-reaction kettle 2; the collected liquid water is used for tail gas washing or recycling, the pre-reaction kettle 2 is maintained at 0.01-0.03 MPa micro-positive pressure to promote water vapor discharge, and the water discharge rate is monitored online to determine the esterification process; constant temperature stirring is carried out in the pre-reaction kettle 2, which can be specifically 220-250°C, and the esterification reaction is continuously carried out until the acid value is reduced to the target range specified in the formula process; it should be noted that the stirring speed in the pre-reaction kettle 2 is adapted to the change of viscosity, and in the later stage of pre-reaction, the stirring speed is increased to medium speed, 30-60 r / min;

[0044] Step four, transfer: the heat exchange unit 7 in the pre-reaction kettle 2 is used to cool the material in the pre-reaction process, and the heat energy in the pre-reaction process is replaced and sent out, and the material is cooled to the temperature specified in the formula process and then sent into the reaction kettle 3 for the next reaction; it should be noted that the material is cooled to 180-220°C, and the inside of the reaction kettle 3 is preheated to 180-220°C to prevent the material from solidifying when it is cooled;

[0045] Step six, polymerization reaction: monomers and reaction aids are added to the inside of the reaction kettle 3, the inside of the reaction kettle 3 is stirred and mixed, the temperature of the material in the reaction kettle 3 is raised to 240-260°C, the heating rate is controlled below 5°C / h to prevent oligomer cracking, and the vacuum system is started to keep the inside of the reaction kettle 3 at a vacuum degree of-0.09--0.1 MPa; the inside of the reaction kettle 3 is kept at a constant temperature, and condensation is carried out under vacuum to make the molecular chain grow until the hydroxyl value meets the process requirements, then the vacuum is maintained to remove small molecules and promote the forward condensation, finally the heat in the inside of the reaction kettle 3 is replaced by the heat exchange unit 7 to cool the inside of the reaction kettle 3 to 180-200°C, the vacuum system is closed, nitrogen is introduced into the inside of the reaction kettle 3 to break the vacuum, and the polyester melt is transported to the underwater pelletizer through the gear pump and the melt filter to cool and solidify into particles, completing the semi-continuous production of polyester resin.

[0046] In one specific embodiment, the present application accurately quantifies the input of powder raw materials and liquid raw materials in step one, ensuring the accuracy of raw material ratio and laying the foundation for stable production; step two uses the premixing unit 5 to preliminarily mix and heat in the pre-reaction kettle body 2, promotes the preliminary reaction of raw materials, and improves the reaction efficiency; step three uses the condenser to recover water vapor, realizes the rational use of water resources, and controls the esterification process accurately; step four adjusts the stirring speed according to the viscosity, ensures uniform and sufficient reaction, and is beneficial to stable acid value; step five realizes cooling and heat replacement by heat exchange unit 7, saves energy and avoids material solidification, and preheating reaction kettle body 3 ensures production continuity; step six adds materials, accurately controls temperature and operates in vacuum, promotes molecular chain growth and small molecule removal, improves product quality, and efficiently completes production underwater, the overall scheme improves production efficiency and product quality, realizes energy saving and rational use of resources, and cooperates with each structure to ensure stable and efficient operation of the process, promotes the progress of semi-continuous production technology of polyester resin for powder coatings.

[0047] Specifically, the reaction body 1 is composed of a pre-reaction kettle body 2, a reaction kettle body 3 and a kettle body sealing cover 4, the top of the reaction kettle body 3 is sealingly connected with the pre-reaction kettle body 2 through a connecting flange, and the top of the pre-reaction kettle body 2 is further sealingly connected with the kettle body sealing cover 4 through a bolt; the inside of the reaction kettle body 3 is provided with a reaction unit 6, and the inside of the pre-reaction kettle body 2 and the reaction kettle body 3 are both provided with a heat exchange unit 7; the inside of the pre-reaction kettle body 2 is further fixedly provided with a material separation frame 8, the inside of the material separation frame 8 is provided with a plurality of material guide holes 9, the inside of the material guide holes 9 is respectively communicated with the inside of the pre-reaction kettle body 2 and the reaction kettle body 3, and the inside of the material guide holes 9 is further provided with an automatic control valve, by opening and closing the automatic control valve, the communication and isolation of the inside of the pre-reaction kettle body 2 and the reaction kettle body 3 is realized, in addition, the material guide holes 9 are designed in the shape of a truncated cone, the upper end diameter of the material guide holes 9 is larger than the lower end diameter, and the inner wall of the material guide holes 9 is further provided with a plurality of turbulence strips, so that the material has a further mixing effect when passing through the material guide holes 9 into the inside of the reaction kettle body 3.

[0048] The inside of the pre-reaction kettle body 2 is provided with a premixing unit 5 for initial mixing of powder raw materials and liquid raw materials, the premixing unit 5 comprises a raw material conveying frame 10, a pre-reaction rotating shaft 16 and a pre-reaction mixing frame 17, the top of the inner wall of the kettle body sealing cover 4 and the upper part of the inside of the pre-reaction kettle body 2 are fixedly provided with the raw material conveying frame 10, and the inside of the two raw material conveying frames 10 is provided with a conveying cavity 12; one side of the two raw material conveying frames 10 is provided with a feeding pipe, and one end of the two feeding pipes extends to one side of the pre-reaction kettle body 2; the inside of the pre-reaction kettle body 2 is also rotatably provided with the pre-reaction rotating shaft 16, the top of the kettle body sealing cover 4 is fixedly provided with a reaction control servo motor 15, and the bottom end of the output shaft of the reaction control servo motor 15 is fixedly connected with the top end of the pre-reaction rotating shaft 16 through a connecting shaft; the surface of the pre-reaction rotating shaft 16 is fixedly provided with a distribution frame 13 above and below, the circumference of the distribution frame 13 is sealingly and slidably connected with the inside of the conveying cavity 12, and the outer periphery of the distribution frame 13 is also fixedly provided with a plurality of distribution partitions 14, and one side of the plurality of distribution partitions 14 is in sliding contact with one side of the inner wall of the conveying cavity 12, the inside of the conveying cavity 12 is divided into a plurality of feeding cavities by the plurality of distribution partitions 14, the raw materials are circulated and conveyed in the conveying cavity 12 by the distribution frame 13 and the distribution partitions 14, and the raw materials can be continuously preheated in the circulation process in the conveying cavity 12, thereby further improving the mixing effect of the raw materials entering the inside of the pre-reaction kettle body 2; the bottom of the upper raw material conveying frame 10 and the top of the lower raw material conveying frame 10 are provided with a plurality of discharge ports 11, and the inside of the plurality of discharge ports 11 is provided with an automatic control valve, the automatic control valve is used to realize the on-off of the inside of the discharge port 11, thereby selecting to send the raw materials from the inside of the conveying cavity 12 into the inside of the pre-reaction kettle body 2, or continuously circulating and preheating the raw materials in the inside of the conveying cavity 12; by relatively arranging the discharge ports 11 on the upper and lower raw material conveying frames 10, the upper raw material conveying frame 10 is used for conveying powder raw materials, and the lower raw material conveying frame 10 is used for conveying liquid raw materials, by using the relative discharging mode, the liquid raw materials at the lower part are sprayed, and the powder raw materials at the upper part are sent out in a dispersed manner, the contact area between the two is maximized, thereby greatly improving the premixing effect of the raw materials.

[0049] Further, the outer periphery of the pre-reaction rotating shaft 16 is also fixedly provided with a pre-reaction mixing frame 17, the pre-reaction mixing frame 17 is driven by the pre-reaction rotating shaft 16 to rotate in the inside of the pre-reaction kettle body 2, thereby realizing the premixing operation of the raw materials in the inside of the pre-reaction kettle body 2; in addition, an electric heating element and a temperature sensor are also arranged in the inside of the pre-reaction kettle body 2, which are used to accurately control the reaction temperature in the inside of the pre-reaction kettle body 2.

[0050] In a specific embodiment, the reaction body 1 in the present application is composed of a pre-reaction kettle body 2, a reaction kettle body 3 and a kettle body sealing cover 4. The combination connection mode guarantees the sealing and stability of the reaction system. The material separation frame 8 and the conical guide hole 9 with a spoiler strip in the pre-reaction kettle body 2 can further mix the material when passing through to improve the uniformity of the material. In the premixing unit 5, the raw material conveying frame 10, the pre-reaction rotating shaft 16 and the pre-reaction mixing frame 17 work cooperatively, and the conveying cavity 12, the material distribution frame 13 and the material distribution partition plate 14 cooperate to make the raw material circulate and preheat in the conveying cavity 12. The oppositely arranged discharge port 11 sprays liquid raw materials and dispersively sends powder raw materials in a spray state, greatly improving the raw material contact area and the premixing effect. The pre-reaction rotating shaft 16 drives the pre-reaction mixing frame 17 to rotate to further strengthen the premixing. The electric heating element and the temperature sensor accurately control the temperature to guarantee the stability of the pre-reaction temperature. The overall design improves the raw material premixing effect, the reaction temperature accuracy and the material mixing uniformity in the polyester resin semi-continuous production from raw material conveying, premixing, temperature control to material transfer and mixing, lays a foundation for the subsequent esterification and polycondensation reaction, promotes the production efficiency and product quality, and improves the production efficiency and product quality. The reaction body 1, the pre-reaction kettle body 2, the reaction kettle body 3, the kettle body sealing cover 4, the premixing unit 5, the material separation frame 8, the guide hole 9, the raw material conveying frame 10, the conveying cavity 12, the material distribution frame 13, the material distribution partition plate 14, the reaction control servo motor 15, the pre-reaction rotating shaft 16 and the pre-reaction mixing frame 17 cooperate with each other to build an efficient, accurate and stable production system.

[0051] Specifically, the reaction unit 6 comprises a reaction transmission frame 18 and a mixing stirring shaft 19, the bottom of the material separating frame 8 is fixedly provided with the reaction transmission frame 18, and the bottom end of the pre-reaction rotating shaft 16 extends to the inside of the reaction transmission frame 18, the upper part of the inside of the reaction transmission frame 18 is rotatably provided with a driving gear 20, and the bottom end of the pre-reaction rotating shaft 16 is fixedly connected with the inside of the driving gear 20; the top of the inner wall of the reaction transmission frame 18 is also rotatably provided with three transmission gears 21, and the tooth surfaces of the three transmission gears 21 are all in meshing transmission with the tooth surfaces of the driving gear 20, and the middle part of the inside of the reaction transmission frame 18 is also rotatably provided with an inner tooth ring 22, and the tooth surfaces of the three reaction transmission frames 18 are all in meshing transmission with the inner tooth surfaces of the inner tooth ring 22; the bottom of the inner tooth ring 22 is fixedly provided with the mixing stirring shaft 19, and the bottom end of the mixing stirring shaft 19 extends to below the reaction transmission frame 18; the surface of the mixing stirring shaft 19 is also provided with a plurality of air guide holes, and the lower part of the inside of the reaction transmission frame 18 is also fixedly provided with an air guide ring 28, one side of the air guide ring 28 is fixedly provided with a pneumatic pump, and specifically, the pneumatic pump is a plunger type pneumatic pump; the inside of the air guide ring 28 is provided with an air guide flow channel, and the inside of the air guide flow channel is in communication with the insides of the plurality of air guide holes; the inside of the air guide ring 28 is rotatably connected with the surface of the mixing stirring shaft 19, and a sealing ring is arranged between the air guide ring 28 and the mixing stirring shaft 19, so as to ensure that the mixing stirring shaft 19 can rotate without interference, and at the same time, the plurality of air guide holes arranged on the surface of the mixing stirring shaft 19 can be sealingly connected with the air guide flow channel in the inside of the air guide ring 28.

[0052] Further, the surface of the mixing stirring shaft 19 below the reaction transmission frame 18 is fixedly provided with a flat paddle 23, an inclined paddle 24 and an anchor paddle 25 from top to bottom; the inside of the mixing stirring shaft 19 is provided with a circulating feeding port 26, and the bottom end of the circulating feeding port 26 penetrates through the bottom of the mixing stirring shaft 19, the top end of the circulating feeding port 26 is in communication with the insides of the plurality of air guide holes, and the inside of the flat paddle 23 is also provided with a circulating discharging port 27, and the inside of the circulating discharging port 27 is in communication with the inside of the circulating feeding port 26.

[0053] It should be noted that when the mixture in the reaction kettle body 3 is mixed and reacted, the pre-reaction rotating shaft 16 drives the driving gear 20 to rotate, the transmission gear 21 and the inner tooth ring 22 are engaged and driven, the inner tooth ring 22 rotates synchronously with the driving gear 20, the rotating speed of the inner tooth ring 22 is different from that of the driving gear 20, the rotating speed of the inner tooth ring 22 is lower than that of the driving gear 20, so that the stirring speeds in the pre-reaction kettle body 2 and the reaction kettle body 3 are different, so as to adapt to the two rotating speed requirements of the reaction material in the pre-mixing and reaction process; then the inner tooth ring 22 drives the bottom mixing stirring shaft 19 to rotate, the flat paddle 23, the inclined paddle 24 and the anchor paddle 25 arranged on the surface of the mixing stirring shaft 19 are used to stir the material in the reaction kettle body 3 in different directions, the flat paddle 23 is used to rotate to push the material to circulate axially, to form a large circulation of “upside down under the liquid surface → upwelling at the kettle bottom”, to solve the problem of “stratification” of the upper material; the inclined paddle 24 is used to rotate to generate radial vortex + shear force to “scatter” the axially circulated material, and to break the agglomerated particles at the same time; the anchor paddle 25 is used to scrape the dead zone at the bottom of the reaction kettle body 3 to prevent high-viscosity material from depositing and locally overheating.

[0054] In a specific embodiment, the reaction unit 6 of the present application, the reaction transmission frame 18, the mixing stirring shaft 19 and other components cooperate, the pre-reaction rotating shaft 16 drives the driving gear 20, the transmission gear 21 and the inner tooth ring 22 are engaged and driven, the inner tooth ring 22 rotates synchronously with the driving gear 20 but at different speeds, to adapt to the different rotating speed requirements of the pre-mixing and reaction of the materials in the pre-reaction kettle body 2 and the reaction kettle body 3. The flat paddle 23, the inclined paddle 24 and the anchor paddle 25 arranged on the surface of the mixing stirring shaft 19 have clear division of labor, the flat paddle 23 pushes the material to circulate axially to solve the problem of stratification of the upper layer; the inclined paddle 24 generates radial vortex and shear force to scatter the material and break the agglomerated particles; the anchor paddle 25 scrapes the dead zone at the bottom of the kettle to prevent material deposition and overheating. At the same time, the inner circulating feed inlet 26 of the mixing stirring shaft 19, the air guide hole and the air guide ring 28 cooperate to combine with the plunger type pneumatic pump to assist material mixing and reaction environment control, and the sealing ring ensures the sealing performance of the air guide system and the flexibility of the stirring shaft rotation; the reaction unit 6, the reaction transmission frame 18, the mixing stirring shaft 19, the driving gear 20, the transmission gear 21, the inner tooth ring 22, the flat paddle 23, the inclined paddle 24, the anchor paddle 25, the circulating feed inlet 26, the circulating discharge outlet 27 and the air guide ring 28 cooperate with each other to greatly improve the uniformity of the material mixing in the reaction kettle body 3, the reaction stability, optimize the stirring effect, provide an efficient and adaptive reaction environment for polyester resin synthesis, and help to improve production efficiency and product quality.

[0055] Specifically, the heat exchange unit 7 comprises heat exchange liners 29, the inside of the pre-reaction kettle body 2 and the reaction kettle body 3 are fixedly provided with the heat exchange liners 29, the inner wall of the pre-reaction kettle body 2 and the outer side of the heat exchange liner 29 and the inner wall of the reaction kettle body 3 and the outer side of the heat exchange liner 29 are fixedly provided with spiral flow guides 30, and the inside of the two heat exchange liners 29 is provided with spiral heat exchange flow channels 31; the upper and lower parts of the inside of the two spiral heat exchange flow channels 31 are provided with circulating heat exchange interfaces, the upper and lower parts of the spiral flow guides 30 in the pre-reaction kettle body 2 and the reaction kettle body 3 are provided with circulating material guide interfaces, and the inside of the spiral flow guides 30 in the pre-reaction kettle body 2 and the reaction kettle body 3 are communicated through automatic control valves; the inside of the pre-reaction kettle body 2 and the reaction kettle body 3 is also communicated with a vacuum system, and the inside of the pre-reaction kettle body 2 is also communicated with a condensation system; the bottom of the reaction kettle body 3 is provided with a discharge pipe.

[0056] It should be noted that when preheating the inside of the pre-reaction kettle body 2 and the reaction kettle body 3, high-temperature oil is sent into the inside of the spiral flow guides 30 and the spiral heat exchange flow channels 31, so that the high-temperature oil flows spirally in the inside of the pre-reaction kettle body 2 and the reaction kettle body 3, realizing rapid preheating treatment of the inside of the pre-reaction kettle body 2 and the reaction kettle body 3, and the high-temperature oil flowing in the spiral flow guides 30 and the spiral heat exchange flow channels 31 can also have a heat preservation effect on the reaction in the inside of the pre-reaction kettle body 2 and the reaction kettle body 3; when the material in the inside of the pre-reaction kettle body 2 and the reaction kettle body 3 is cooled, the high-temperature oil in the inside of the spiral heat exchange flow channels 31 and the spiral flow guides 30 is replaced by heat exchange medium, so that the heat in the inside of the pre-reaction kettle body 2 and the reaction kettle body 3 is replaced out, realizing rapid recovery of the reaction heat in the inside of the pre-reaction kettle body 2 and the reaction kettle body 3, and reducing the waste of heat energy in the reaction process.

[0057] In a specific embodiment, the heat exchange unit 7 of the present application, the heat exchange bushing 29, the spiral guide frame 30 and the spiral heat exchange flow channel 31 constitute the core structure. In the preheating stage, high-temperature oil enters the spiral guide frame 30 and the spiral heat exchange flow channel 31 through the circulating heat exchange interface and the circulating guide interface, and flows spirally in the pre-reaction kettle body 2 and the reaction kettle body 3, thereby achieving rapid and uniform preheating by virtue of large-area contact and spiral path, and providing a suitable starting temperature for the reaction; in the reaction process, the continuously flowing high-temperature oil can also play a heat preservation role for the pre-reaction kettle body 2 and the reaction kettle body 3, thereby maintaining the reaction temperature stable and ensuring the smooth progress of the reaction. In the cooling stage, the high-temperature oil in the spiral guide frame 30 and the spiral heat exchange flow channel 31 is replaced by a heat exchange medium, which can efficiently replace the heat in the kettle, rapidly cool the material, and at the same time realize the recycling of reaction heat, reduce the waste of heat energy, and meet the energy-saving production needs. In addition, the automatic control valve controls the internal communication of the spiral guide frame 30, which can flexibly regulate and control the flow path of the material and the heat exchange medium, and the vacuum system and the condensation system cooperate to further optimize the reaction environment. The design of the entire heat exchange unit 7 effectively improves the accuracy, efficiency and energy saving of the temperature control of the pre-reaction kettle body 2 and the reaction kettle body 3, provides stable and reliable temperature protection for the semi-continuous production of polyester resin, and improves the production efficiency and energy utilization rate.

[0058] Meanwhile, the contents not described in detail in the present specification all belong to the prior art known to those skilled in the art.

[0059] It should be noted that, in this paper, relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. Moreover, the terms "include", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment.

[0060] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirits of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A semi-continuous production process for polyester resin in powder coatings, characterized in that, Includes the following steps: Step 1, Raw material delivery: The powder raw materials after dispersion and impurity removal are quantitatively added into the interior of the reaction body (1) according to the formula process requirements. At the same time, the liquid raw materials are quantitatively delivered into the interior of the reaction body (1) according to the formula process requirements using a metering pump. Step 2, raw material premixing: Inside the reaction body (1), the powder raw materials and liquid raw materials are first premixed inside the pre-reaction vessel (2) through the premixing unit (5), and at the same time the heating system inside the pre-reaction vessel (2) is turned on to gradually raise the temperature of the mixed raw materials from room temperature to the temperature specified in the drug preparation process. Step 3, Esterification reaction: Water generated in the reaction inside the pre-reaction vessel (2) escapes in the form of steam and is recovered through a condenser connected to the inside of the pre-reaction vessel (2); The esterification reaction is carried out continuously with constant temperature stirring inside the pre-reaction vessel (2) until the acid value drops to the target range specified in the formulation process. Step 4, material transfer: The heat exchange unit (7) inside the pre-reaction vessel (2) is used to cool down the material during the pre-reaction process. At the same time, the heat energy during the pre-reaction process is replaced and sent out. After the material is cooled down to the temperature specified in the formula process, it is sent into the interior of the reaction vessel (3) for the next reaction. Step 5, Polymerization reaction: Add monomers and reaction aids to the inside of the reactor body (3), stir and mix inside the reactor body (3), and start the vacuum system at the same time to keep the inside of the reactor body (3) at the set vacuum level; keep the inside of the reactor body (3) at a constant temperature and carry out polycondensation under vacuum to increase the molecular chain until the hydroxyl value reaches the process requirements. Maintain the vacuum, remove small molecules, and promote the forward polycondensation. Finally, use the heat exchange unit (7) to replace the heat inside the reactor body (3) to cool the inside of the reactor body (3) to 180-200℃. Close the vacuum system and introduce nitrogen into the inside of the reactor body (3) to break the vacuum. Through the gear pump and melt filter, transport the polyester melt to the underwater pelletizer, cool and solidify into pellets to complete the semi-continuous production of polyester resin.

2. The semi-continuous production process of polyester resin for powder coating according to claim 1, characterized in that, The reaction body (1) consists of a pre-reaction vessel (2), a reaction vessel (3) and a vessel sealing cover (4). The top of the reaction vessel (3) is sealed to the pre-reaction vessel (2) by a connecting flange, and the top of the pre-reaction vessel (2) is also sealed to the vessel sealing cover (4) by bolts. A material separator (8) is fixedly installed at the bottom inside the pre-reaction vessel (2), and the material separator (8) has several material guide holes (9) inside. The material guide holes (9) are respectively connected to the interior of the pre-reaction vessel (2) and the reaction vessel (3), and an automatic control valve is also installed inside the material guide holes (9).

3. The semi-continuous production process of polyester resin for powder coating according to claim 2, characterized in that, The guide hole (9) adopts a frustum-shaped design. The upper diameter of the guide hole (9) is larger than the lower diameter, and the inner wall of the guide hole (9) is also provided with several baffles.

4. The semi-continuous production process of polyester resin for powder coating according to claim 2, characterized in that, The pre-reaction vessel body (2) is equipped with a pre-mixing unit (5) for initial mixing of powder raw materials and liquid raw materials. The pre-mixing unit (5) includes a raw material conveying rack (10), a pre-reaction rotating shaft (16), and a pre-reaction mixing rack (17). The top of the inner wall of the vessel body sealing cover (4) and the upper part of the interior of the pre-reaction vessel body (2) are both fixedly equipped with raw material conveying racks (10), and both raw material conveying racks (10) are equipped with conveying chambers (12). The pre-reaction rotating shaft (16) is also rotatably installed inside the pre-reaction vessel body (2), and the pre-reaction mixing rack (17) is also fixedly installed on the outer circumferential surface of the pre-reaction rotating shaft (16). The top of the vessel body sealing cover (4) is fixedly equipped with a reaction control servo motor (15), and the bottom end of the output shaft of the reaction control servo motor (15) is fixedly connected to the top end of the pre-reaction rotating shaft (16) through a connecting shaft.

5. The semi-continuous production process of polyester resin for powder coating according to claim 4, characterized in that, The pre-reaction rotating shaft (16) is fixedly provided with a material distribution rack (13) on both the upper and lower surfaces. The circumference of the material distribution rack (13) is sealed and slidably connected to the inside of the conveying cavity (12). The outer circumferential surface of the material distribution rack (13) is also fixedly provided with several material distribution partitions (14). One side of each of the several material distribution partitions (14) is in sliding contact with one side of the inner wall of the conveying cavity (12). The bottom of the raw material conveying rack (10) located above and the top of the raw material conveying rack (10) located below are provided with several discharge ports (11). The interior of each of the several discharge ports (11) is provided with an automatic control valve.

6. The semi-continuous production process of polyester resin for powder coating according to claim 4, characterized in that, The reactor body (3) is equipped with a reaction unit (6); the reaction unit (6) includes a reaction transmission frame (18) and a mixing and stirring shaft (19). The bottom of the material separator (8) is fixedly provided with the reaction transmission frame (18), and the bottom end of the pre-reaction rotating shaft (16) extends into the interior of the reaction transmission frame (18). A drive gear (20) is rotatably provided above the interior of the reaction transmission frame (18), and the bottom end of the pre-reaction rotating shaft (16) is fixedly connected to the interior of the drive gear (20). Three transmission gears (21) are rotatably arranged on the top of the inner wall, and the tooth surfaces of the three transmission gears (21) mesh with the tooth surfaces of the drive gear (20). An internal toothed ring (22) is rotatably arranged in the middle of the interior of the reaction transmission frame (18), and the tooth surfaces of the three reaction transmission frames (18) mesh with the internal tooth surfaces of the internal toothed ring (22). A mixing and stirring shaft (19) is fixedly arranged at the bottom of the internal toothed ring (22), and the bottom end of the mixing and stirring shaft (19) extends to the bottom of the reaction transmission frame (18).

7. The semi-continuous production process for polyester resin in powder coatings according to claim 6, characterized in that, The surface of the mixing and stirring shaft (19) is also provided with several air guide holes. An air guide ring (28) is fixedly provided at the bottom inside the reaction transmission frame (18), and a pneumatic pump is fixedly provided on one side of the air guide ring (28). An air guide channel is provided inside the air guide ring (28), and the inside of the air guide channel is connected to the inside of several air guide holes.

8. The semi-continuous production process of polyester resin for powder coating according to claim 6, characterized in that, The mixing shaft (19) is located below the reaction transmission frame (18) and is fixedly provided with a straight blade (23), an inclined blade (24) and an anchor blade (25) from top to bottom. The mixing shaft (19) is provided with a circulating feed inlet (26), and the bottom end of the circulating feed inlet (26) penetrates the bottom of the mixing shaft (19). The top end of the circulating feed inlet (26) is connected to the interior of several air guide holes. The straight blade (23) is also provided with a circulating discharge outlet (27), and the interior of the circulating discharge outlet (27) is connected to the interior of the circulating feed inlet (26).

9. The semi-continuous production process of polyester resin for powder coating according to claim 2, characterized in that, Both the pre-reaction vessel (2) and the reaction vessel (3) are equipped with heat exchange units (7); each heat exchange unit (7) includes a heat exchange bushing (29). Both the pre-reaction vessel (2) and the reaction vessel (3) are fixedly equipped with heat exchange bushings (29). A spiral guide frame (30) is fixedly installed between the inner wall of the pre-reaction vessel (2) and the outer side of the heat exchange bushing (29) and between the inner wall of the reaction vessel (3) and the outer side of the heat exchange bushing (29). Both heat exchange bushings (29) are equipped with spiral heat exchange channels (31).

10. The semi-continuous production process of polyester resin for powder coating according to claim 9, characterized in that, Both of the spiral heat exchange channels (31) are provided with circulating heat exchange interfaces at the top and bottom. Both the spiral guide frame (30) inside the pre-reaction vessel (2) and the reaction vessel (3) are provided with circulating material guide interfaces at the top and bottom. The spiral guide frame (30) inside the pre-reaction vessel (2) and the reaction vessel (3) are connected by an automatic control valve. The interior of the pre-reaction vessel (2) and the reaction vessel (3) is also connected to a vacuum system, and the interior of the pre-reaction vessel (2) is also connected to a condensation system. The bottom of the reaction vessel (3) is provided with a discharge pipe.

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