Reactor for PMMA polymerization reaction

Abstract

This invention relates to a reactor for PMMA polymerization, comprising: a reaction vessel; a stirring shaft, one end of which is located inside the reaction vessel and the other end of which extends out of the reaction vessel; a stirring assembly disposed at the end of the stirring shaft located inside the reaction vessel; a drive component connected to the end of the stirring shaft extending out of the reaction vessel; and a heat-conducting component disposed on the outer wall of the reaction vessel. The heat-conducting component has a cavity for allowing heat transfer oil to flow and an oil inlet and an oil outlet communicating with the cavity. The reactor of this invention can achieve uniform mixing of reactants, maintain a specific reaction temperature, and achieve a multi-stage stable conversion rate for optimal polymerization quality.

Description

Technical Field

[0001] This invention relates to the field of PMMA production, and more particularly to a reactor for PMMA polymerization reactions. Background Technology

[0002] Polymethyl methacrylate (PMMA), also known as plexiglass, is one of the three most important light-transmitting materials in the field of new chemical materials. It is widely used in the automotive, transportation, general injection molding, light box advertising, and construction industries. In recent years, with the development of high-transmittance PMMA products, high-grade PMMA applications have entered cutting-edge fields such as LED / LCP displays, optical materials, optical fibers, and medical materials. Furthermore, with the trend towards lightweighting in automobiles, the proportion of high-transmittance materials used in automotive applications is increasing year by year.

[0003] Polymethyl methacrylate (PMMA) is a copolymer primarily composed of methyl methacrylate (MMA) and a small amount of acrylate monomers. The polymerization processes mainly include suspension polymerization, solution polymerization, and bulk polymerization. While production conditions differ, the polymerization process remains the core of the technology, and different polymerization reactors significantly impact the structure and properties of the polymerized product. Polymerization reactors can be categorized by form into batch reactors, tower reactors, tubular reactors, and special types, with stirred batch reactors being the most widely used in polymerization processes.

[0004] Patent CN201200888Y discloses a stirred tank. In this device, the stirring shaft and impeller are located inside the stirred tank and are driven to rotate, completing the stirring operation. A jacket is installed outside the stirred tank for heat preservation. However, in the PMMA polymerization reaction, the internal temperature must be strictly controlled; otherwise, PMMA will depolymerize, and the monomer conversion rate will fluctuate wildly with temperature changes, causing a rapid increase in the overall reaction efficiency, leading to runaway reaction and alterations in polymer properties. The jacket in this patent cannot maintain the specific temperature required for the PMMA polymerization reaction inside the stirred tank. Summary of the Invention

[0005] The purpose of this invention is to provide a reactor for PMMA polymerization that can maintain the reaction temperature.

[0006] To achieve the above objectives, the present invention provides a reactor for PMMA polymerization, comprising:

[0007] reaction vessel;

[0008] The stirring shaft has one end located inside the reaction vessel and the other end extending out of the reaction vessel;

[0009] A stirring assembly is disposed at one end of the stirring shaft located in the reaction vessel;

[0010] A drive unit is connected to one end of the stirring shaft that extends out of the reaction vessel;

[0011] A heat-conducting component is disposed on the outer wall of the reaction vessel;

[0012] The heat-conducting component is provided with a cavity for the flow of heat-conducting oil and an oil inlet and an oil outlet connecting the cavity.

[0013] According to one aspect of the invention, the heat-conducting element is a semi-circular tube coil jacket.

[0014] According to one aspect of the invention, the heat-conducting element is fixed to the outer wall of the reaction vessel by welding.

[0015] According to one aspect of the invention, the stirring assembly includes two stirring blades and an anchor-type stirring blade arranged alternately on the stirring shaft;

[0016] The anchor-type agitator is closest to the bottom of the reaction vessel.

[0017] According to one aspect of the invention, the blades of the anchor-type stirring paddle are provided with PTFE scrapers.

[0018] According to one aspect of the invention, the two agitators are arranged in parallel, and the agitators and the anchor agitator are at an angle to each other.

[0019] According to one aspect of the invention, the longitudinal section of the impeller is triangular, and the longitudinal section of the anchor impeller is U-shaped.

[0020] According to one aspect of the invention, the driving element is a variable frequency motor.

[0021] According to the concept of the present invention, a specially designed reaction tank with stirring is used to ensure that the high-viscosity materials in the reaction tank are mixed evenly. At the same time, the polymerization reaction temperature is precisely controlled by external heat-conducting components. Unreacted monomers and oligomers are recycled. Under the combined effect, the optimal polymerization quality is achieved through a multi-stage stable conversion rate.

[0022] According to one aspect of the present invention, the heat-conducting component outside the reaction vessel is a semi-circular coil jacket, and heat-conducting oil is continuously circulated in the heat-conducting component, which can continuously provide heat to the reaction or absorb the reaction heat (heat removal), thereby maintaining the specific reaction temperature of the PMMA polymerization reaction.

[0023] According to one aspect of the present invention, the reaction vessel is equipped with a stirring shaft and a stirring assembly, the stirring assembly including two stirring paddles and an anchor-type stirring paddle. Driven by a variable frequency motor, uniform mixing of materials and uniform temperature distribution within the reaction vessel can be ensured.

[0024] According to one aspect of the present invention, the blades of the anchor-type stirring paddle are provided with PTFE scrapers. During the rotation of the anchor-type stirring paddle, the PTFE scrapers are in close contact with the inner wall of the reaction vessel, which can scrape up the material attached to the vessel wall and make it move along the flow field inside the vessel, thereby making the material more uniformly mixed. Attached Figure Description

[0025] Figure 1 This is a structural diagram of a reactor for PMMA polymerization according to one embodiment of the present invention. Detailed Implementation

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0027] When describing embodiments of the present invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer" express orientations or positional relationships based on the orientations or positional relationships shown in the relevant drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limitations on the present invention.

[0028] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The embodiments cannot be described in detail here, but the embodiments of the present invention are not limited to the following embodiments.

[0029] Figure 1 This is a structural diagram of a reactor for PMMA polymerization according to one embodiment of the present invention. Figure 1As shown, the reactor of this invention is mainly used for the polymerization reaction of PMMA. It mainly includes: a reaction tank 1, a stirring shaft 2, a stirring assembly 3, a drive unit 4, and a heat-conducting component 5. One end of the stirring shaft 2 is located in the reaction tank 1, and the other end extends out from the top of the reaction tank 1 and connects to the drive unit 4. In this invention, the drive unit 4 is a variable frequency motor, thereby realizing variable frequency drive of the stirring shaft 2. The stirring assembly 3 includes two stirring paddles 31 and one anchor-type stirring paddle 32. These three stirring paddles are arranged alternately at the end of the stirring shaft 2 located in the reaction tank 1. The anchor-type stirring paddle 32 is located at the bottom, and the curvature of its anchor blades is basically the same as that of the bottom of the reaction tank 1. In this way, the stirring of the three layers of stirring paddles can form a uniform flow field in the tank and also ensure a uniform temperature distribution within the reaction tank 1. Combined with the variable frequency drive of the variable frequency motor, the residence time of the reactants in the reactor can be kept constant. The anchor-type agitator 32 is equipped with PTFE scrapers on its blades. During the rotation of the anchor-type agitator 32, the PTFE scrapers adhere closely to the wall of the reaction vessel 1, scraping up the material adhering to the wall and causing it to move along the flow field inside the vessel, ensuring uniform mixing of the reactants. The two upper agitators 31 are arranged in parallel with a triangular longitudinal section, and the upper agitator 31 and the lower horizontal blade of the lower anchor-type agitator 32 are set at a specific angle (the specific angle is set according to requirements). The lower anchor-type agitator 32 has a U-shaped longitudinal section.

[0030] The heat-conducting component 5 is located outside the reaction vessel 1. The heat-conducting component 5 is a semi-circular coil jacket, which is fixed to the outer wall of the reaction vessel 1 by spiral welding to form a cavity, and has an oil inlet and an oil outlet communicating with the cavity. This type of coil has a high heat transfer coefficient and is suitable for high-pressure operation. Due to the fin effect of heat transfer, the gap between adjacent coils can still play a role in heat transfer. To ensure the heat dissipation effect of the jacket, the heat transfer oil adopts a multi-point inlet / outlet design. Thus, the heat transfer oil continuously flows from the oil inlet into the cavity of the heat-conducting component 5 and then flows out from the oil outlet. This continuously provides heat to the reaction inside the reaction vessel 1 or absorbs the heat of the reaction (heat dissipation), thereby maintaining the specific reaction temperature of the PMMA polymerization reaction, ensuring a constant discharge temperature, and achieving a multi-stage stable conversion rate for optimal polymerization quality.

[0031] The reactor designed above, when in use, as follows: Figure 1 As shown, the reaction feed, initiator, heat stabilizer, and chain transfer agent are introduced from the top of reaction tank 1, where the polymerization reaction occurs. Stirring by the various agitator blades ensures uniform mixing of the materials, maintaining a monomer conversion rate of 50-60%. During the reaction, the heat transfer oil flowing through the heat-conducting component 5 continuously maintains the specific reaction temperature for the polymerization reaction.

[0032] The above description is merely one embodiment of the present invention and is not intended to limit the invention. Those skilled in the art will recognize that the present invention can be modified and varied in various ways. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A reactor for the polymerization reaction of PMMA, comprising: Reaction vessel (1); The stirring shaft (2) has one end located in the reaction tank (1) and the other end extending out of the reaction tank (1); A stirring assembly (3) is disposed at one end of the stirring shaft (2) located in the reaction vessel (1); A drive unit (4) is connected to one end of the stirring shaft (2) that extends out of the reaction vessel (1); A heat-conducting component (5) is disposed on the outer wall of the reaction vessel (1); The feature is that the heat-conducting component (5) is provided with a cavity for the flow of heat-conducting oil and an oil inlet and an oil outlet connecting the cavity. The heat-conducting component (5) is a semi-circular tube coil jacket, and the heat-conducting oil adopts a multi-point inlet / outlet design. The stirring assembly (3) includes two stirring paddles (31) arranged alternately on the stirring shaft (2) and an anchor-type stirring paddle (32); The anchor-type stirring paddle (32) is closest to the bottom of the reaction vessel (1); The two agitators (31) are arranged in parallel, and the agitators (31) and the anchor agitator (32) have an angle between them; The longitudinal section of the stirring paddle (31) is triangular, and the longitudinal section of the anchor-type stirring paddle (32) is U-shaped; The reaction feed, along with the initiator, heat stabilizer, and chain transfer agent, is introduced from the top of the reaction vessel (1).

2. The reactor for PMMA polymerization according to claim 1, characterized in that, The heat-conducting component (5) is fixed to the outer wall of the reaction vessel (1) by welding.

3. The reactor for PMMA polymerization according to claim 1, characterized in that, The anchor-type stirring paddle (32) is equipped with a PTFE scraper on its blades.

4. The reactor for PMMA polymerization according to any one of claims 1-3, characterized in that, The drive component (4) is a variable frequency motor.

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