Methyl methacrylate polymer preparation device and preparation method thereof

Abstract

The invention relates to the technical field of polymer preparation, and particularly discloses a methyl methacrylate polymer preparation device and a preparation method thereof.The device comprises a polymerization kettle, a switch, a first reactor, a second reactor, a tubular heat exchanger and a devolatilization extruder; through the novel device and the optimized process method, the efficiency, the stability and the product performance of methyl methacrylate polymerization are remarkably improved, and the problems that in the prior art, a first initiator and a second initiator are added into a tank reactor at the same time, when the temperature rises to the initiation temperature of the second initiator, the first initiator and the second initiator are added at the same time, and the polymerization time is shortened are solved. The temperature continues to rise, and the over-temperature and over-pressure risk is caused. The new scheme provided by the invention has obvious advantages in industrial application, is especially suitable for production of high-end PMMA products, and has important market promotion value and social benefits.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer preparation, and particularly relates to a methyl methacrylate polymer preparation device and a preparation method thereof. Background Art

[0002] Polymethyl methacrylate (PMMA) is an important plastic polymer material that was developed earlier. It has good transparency, chemical stability and weather resistance, is easy to dye and process, and has a beautiful appearance. It is widely used in the fields of architecture, optical instruments, electronics, etc.

[0003] PMMA is usually synthesized from methyl methacrylate (MMA) by the following methods: 1. suspension polymerization, 2. solution polymerization, 3. bulk polymerization, and 4. emulsion polymerization. Among them, bulk polymerization can directly produce the final product, while other methods still require melt calendering, extrusion, injection molding, vacuum forming and other process steps.

[0004] In the Chinese patent with publication number CN113999339A, a method for preparing polymethyl methacrylate is mentioned, comprising the following steps: 1. Taking 80 to 100 parts by weight of methyl methacrylate, 10 to 20 parts by weight of a comonomer, and 120×10 -4 ~200×10 -4 parts, second initiator 40×10 -4 ~90×10 -4 1. The first initiator and the second initiator are mixed as raw materials, stirred evenly, and added to a kettle reactor for primary polymerization until the polymerization rate is 40-60%; 2. The material after the primary polymerization is heated and input into a tubular reactor for secondary polymerization until the polymerization rate is 70-90%; 3. The material after the secondary polymerization is input into a devolatilizer for devolatilization; The polymer output from the outlet of the devolatilizer is extruded to obtain a product, wherein the extrusion temperature is 240-290°C. Compared with the prior art, the present application can achieve stable production while improving the light transmittance of the product. Although the above scheme has many beneficial effects, the first initiator and the second initiator are added to the polymerization kettle (kettle reactor) at the same time in this scheme. In the case of adding the initiators at the same time, when the temperature rises to the initiation temperature of the second initiator, the temperature will continue to rise, and there is a risk of over-temperature and over-pressure.

[0005] In view of this, the inventors proposed a methyl methacrylate polymer preparation device and a preparation method thereof to solve the above problems. Summary of the invention

[0006] The object of the present invention is to provide a methyl methacrylate polymer preparation device and a preparation method thereof to solve the problems raised in the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A methyl methacrylate polymer preparation device, comprising:

[0009] A polymerization kettle, used for mixing and preliminarily polymerizing raw materials of methyl methacrylate, comonomer, first initiator and chain transfer agent, wherein the polymerization kettle is equipped with a paddle stirrer to ensure sufficient mixing and uniform reaction of the raw materials;

[0010] A switch for controlling the flow rate of the raw materials from the polymerization kettle into the subsequent first reactor;

[0011] A first reactor is used for performing a preliminary reaction, mixing the material from the polymerization kettle with the first initiator and the second initiator, wherein the first reactor is a static mixer structure to ensure the uniformity of the reaction;

[0012] The second reactor is used for further reaction. When a power outage or failure occurs, it can be switched to inject toluene to terminate the reaction and avoid temperature runaway. The second reactor is a static mixer structure;

[0013] A tubular heat exchanger, used to evenly increase the temperature of the resin slurry in the second reactor, which is designed so that the resin passes through the tube layer and the heat transfer oil passes through the shell layer to achieve more uniform heating and reduce the generation of carbides;

[0014] The devolatilizing extruder is used to devolatilize the reacted resin slurry to reduce residual monomers and improve the optical properties and product quality of the polymer.

[0015] A method for preparing a methyl methacrylate polymer, comprising the device wherein the chain transfer agent is at least one of n-butyl mercaptan, isobutyl mercaptan, n-hexyl mercaptan, n-octyl mercaptan or n-dodecyl mercaptan, and the method further comprises the following steps:

[0016] S1, by weight, take 85-105 parts of methyl methacrylate, 12-24 parts of comonomer, 100×10 -4 ~200×10 -4 0.2-0.9 parts of chain transfer agent are mixed as raw materials and stirred evenly, and added into a polymerization kettle for primary polymerization until the polymerization rate reaches 40%-60%, the temperature of the primary polymerization is 95-150° C., the pressure is 0.2-0.7 MPa, the time is 2-4 hours, and stirring is performed during the primary polymerization to obtain a primary polymerization material;

[0017] S2, the primary polymerization material is transferred to the first reactor through the switch, and the first initiator 100×10 -4 ~200×10 -4 parts, second initiator 50×10 -4 ~80×10 -4 share;

[0018] S3, heating the material after the primary polymerization and then inputting it into the second reactor for secondary polymerization, wherein the inlet temperature of the second reactor is 110-170° C., the outlet temperature is 140-190° C., and the polymerization rate of the material at the outlet is 70%-90%, to obtain a secondary polymerization material;

[0019] S4, inputting the secondary polymerization into a tubular heat exchanger to uniformly increase the temperature of the resin slurry to obtain a uniform slurry;

[0020] S5. Input the above-mentioned uniform slurry into a devolatilizing extruder for devolatilization, the devolatilization temperature is 190-270°C, and the devolatilization pressure is 0.0001MPa-0.05MPa; the polymer output from the outlet of the devolatilizing extruder is extruded to obtain a methyl methacrylate polymer product, wherein the extrusion temperature is 240-290°C; the temperature difference between the first initiator and the second initiator when the half-life is 1h is 40-60°C, and the half-life of the first initiator at the polymerization temperature of the primary polymerization is 10 seconds to 2 hours, and the half-life of the second initiator at the polymerization temperature of the secondary polymerization is 0.1 second to 1500 seconds, wherein the polymerization temperature of the secondary polymerization is the average value of the inlet temperature and the outlet temperature in the above step 2.

[0021] Preferably, the comonomer includes at least one of methyl methacrylate and methyl acrylate.

[0022] Preferably, the first initiator is at least one of 2,2'-azobis[N-(2-propenyl)-2-methylpropionamide], tert-butyl peroxyacetate, tert-amyl peroxybenzoic acid and tert-butyl peroxy 3,5,5-trimethylhexanoate; the second initiator is at least one of tert-butyl isopropyl peroxide, 1,1,3,3-tetramethylbutyl hydroperoxide, di-tert-butyl isopropyl peroxide, isopropyl hydroperoxide and di-tert-butyl peroxide.

[0023] Preferably, the half-life of the first initiator at the polymerization temperature of the primary polymerization is 30 seconds to 1 hour; the half-life of the second initiator at the polymerization temperature of the secondary polymerization is 1 second to 1000 seconds.

[0024] Preferably, the chain transfer agent is at least one of n-butyl mercaptan, isobutyl mercaptan, n-hexyl mercaptan, n-octyl mercaptan or n-dodecyl mercaptan.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention significantly improves the efficiency, stability and product performance of methyl methacrylate polymerization through a new device and an optimized process method, and solves the problem that in the conventional technology, the first initiator and the second initiator are added to the kettle reactor at the same time. When the temperature rises to the initiation temperature of the second initiator, the temperature will continue to rise, resulting in the risk of over-temperature and over-pressure. The new scheme of the present invention has obvious advantages in industrial applications, and is particularly suitable for the production of high-end PMMA products, and has important market promotion value and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of a methyl methacrylate polymer preparation device of the present invention;

[0028] In the figure: 1. Polymerization kettle; 2. Switch; 3. First reactor; 4. Second reactor; 5. Tubular heat exchanger; 6. Devolatilization extruder. DETAILED DESCRIPTION

[0029] 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.

[0030] Embodiment 1:

[0031] A methyl methacrylate polymer preparation device, comprising:

[0032] A polymerization kettle 1, used for mixing and preliminarily polymerizing raw materials of methyl methacrylate, comonomer, first initiator and chain transfer agent, wherein the polymerization kettle 1 is equipped with a paddle stirrer to ensure sufficient mixing and uniform reaction of the raw materials;

[0033] Switch 2, used to control the flow rate of raw materials from the polymerization kettle 1 into the subsequent first reactor 3;

[0034] The first reactor 3 is used for performing a preliminary reaction, mixing the material from the polymerization kettle with the first initiator and the second initiator. The first reactor 3 is a static mixer structure to ensure the uniformity of the reaction;

[0035] The second reactor 4 is used for further reaction. When a power outage or failure occurs, it can be switched to inject toluene to terminate the reaction and avoid temperature runaway. The second reactor 4 is a static mixer structure;

[0036] The tubular heat exchanger 5 is used to evenly increase the temperature of the resin slurry in the second reactor 4. The design is that the resin passes through the tube layer and the heat transfer oil passes through the shell layer to achieve more uniform heating and reduce the generation of carbides;

[0037] Devolatilization extruder 6 is used to devolatilize the reacted resin slurry to reduce residual monomers and improve the optical properties and product quality of the polymer.

[0038] Embodiment 2:

[0039] A method for preparing a methyl methacrylate polymer, wherein the raw material ratio is: 90 parts of methyl methacrylate, 10 parts of a comonomer (methyl acrylate), 150×10^-4 parts of a first initiator (tert-butyl peroxy 3,5,5-trimethylhexanoate), 50×10^-4 parts of a second initiator (tert-butyl isopropyl peroxide), and 0.3 parts of a chain transfer agent (n-octyl mercaptan).

[0040] Polymerization process:

[0041] Primary polymerization temperature: 130°C; pressure: 0.5 MPa; stirring speed: 60 r / min; polymerization rate: 52%.

[0042] Secondary polymerization: inlet temperature 140°C, outlet temperature 170°C, polymerization rate: 75%.

[0043] Devolatilization parameters: temperature 260°C, pressure 0.02MPa.

[0044] Advantages:

[0045] In the static mixer structure, the initiator is dispersed more evenly, reducing local overpolymerization.

[0046] The newly designed tubular heat exchanger makes the slurry temperature evenly distributed and improves product quality.

[0047] Embodiment three:

[0048] Raw material ratio: 85 parts of methyl methacrylate, 15 parts of comonomer (ethyl methacrylate), 120×10^-4 parts of the first initiator (tert-butyl peroxyacetate), 60×10^-4 parts of the second initiator (1,1,3,3-tetramethylbutyl hydroperoxide), and 0.4 parts of the chain transfer agent (isobutyl mercaptan).

[0049] Polymerization process:

[0050] Primary polymerization temperature: 120°C; pressure: 0.6 MPa; stirring speed: 50 r / min; polymerization rate: 47%.

[0051] Secondary polymerization: inlet temperature 150°C, outlet temperature 180°C, polymerization rate: 80%.

[0052] Devolatilization parameters: temperature 270°C, pressure 0.015MPa.

[0053] Advantages compared to the embodiment:

[0054] The chain transfer agent ratio is increased to control the polymer molecular weight and obtain a narrower molecular weight distribution.

[0055] By optimizing the ratio of the first initiator to the second initiator, the reaction rate was increased.

[0056] Embodiment 4:

[0057] Raw material ratio: 100 parts of methyl methacrylate, 20 parts of comonomer (isooctyl acrylate), 180×10^-4 parts of the first initiator (tert-butyl peroxy 3,5,5-trimethylhexanoate), 80×10^-4 parts of the second initiator (di-tert-butyl peroxide), and 0.5 parts of the chain transfer agent (n-hexyl mercaptan).

[0058] Polymerization process:

[0059] Primary polymerization temperature: 140°C; pressure: 0.4 MPa; stirring speed: 70 r / min; polymerization rate: 60%.

[0060] Secondary polymerization: inlet temperature 160°C, outlet temperature 190°C, polymerization rate: 85%.

[0061] Devolatilization parameters: temperature 250°C, pressure 0.01MPa.

[0062] Advantages:

[0063] A high proportion of comonomer significantly improves the flexibility and transparency of the polymer.

[0064] Using a higher temperature and pressure for a single polymerization can significantly improve polymerization efficiency.

[0065] The data in the above-mentioned embodiments 2 to 4 are shown in the following table 1:

[0066]

[0067]

[0068] Table 1

[0069] From the above, it can be seen that the primary polymerization and the secondary polymerization are efficiently coordinated: by optimizing the device design and operating parameters, such as using static mixers and tubular heat exchangers, the materials maintain fluidity at high polymerization rates and the reaction is more efficient.

[0070] Optimization of multi-initiator ratio: Adding two initiators at one time makes the reaction more uniform, avoiding the problem of local reaction out of control and efficiency reduction caused by batch addition in traditional methods.

[0071] Narrower molecular weight distribution: Optimizing the ratio of initiator and chain transfer agent can significantly reduce the molecular weight distribution of the final product and improve the mechanical properties and processing stability of the polymer.

[0072] Significantly improved light transmittance: The optimized polymerization and devolatilization processes effectively reduce the dimer content, making the optical properties of polymethyl methacrylate (PMMA) better than comparable documents and suitable for high-end optical products.

[0073] Automation and safety assurance: The device is equipped with a mechanism that can inject toluene to terminate the reaction. In the event of an unexpected power outage or failure, the reaction can be stopped quickly to avoid high-temperature runaway and ensure production safety.

[0074] Uniform heating design: The tubular heat exchanger achieves uniform heating of the resin slurry, reduces carbide generation, ensures product quality and reduces equipment maintenance costs.

[0075] Shorten the reaction time: By adding the dual initiator at one time, the process step of adding the initiator midway is avoided, which significantly shortens the production cycle.

[0076] High polymerization rate output: Operate the equipment at a higher conversion rate to increase product output per unit time and meet large-scale industrial needs.

[0077] Higher raw material utilization rate: Precise control of the chain transfer agent ratio reduces by-product generation, improves raw material utilization rate, and reduces production costs.

[0078] Reduced energy consumption: Optimizing reaction temperature, pressure and stirring speed to reduce the energy consumption of the equipment, which is more energy-saving and environmentally friendly than traditional technologies.

[0079] High flexibility: The equipment and process can adapt to a variety of comonomer and initiator types to meet the different PMMA product specifications, such as high optical transparency materials or enhanced flexibility.

[0080] Environmentally friendly design: No additional release agent is required in the devolatilization process, which reduces environmental pollution and produces polymers with higher purity.

[0081] As can be seen from the above, the efficiency, stability and product performance of methyl methacrylate polymerization are significantly improved through the new device and optimized process method, and the problem of adding the first initiator and the second initiator simultaneously in the kettle reactor in the traditional technology is solved. When the temperature rises to the initiation temperature of the second initiator, the temperature will continue to rise, resulting in the risk of over-temperature and over-pressure. The new scheme of the present invention has obvious advantages in industrial applications, and is particularly suitable for the production of high-end PMMA products, and has important market promotion value and social benefits.

[0082] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0083] In the drawings of the embodiments disclosed in the present invention, only the structures related to the embodiments disclosed in the present invention are involved, and other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of the present invention can be combined with each other.

[0084] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A methyl methacrylate polymer preparation device, characterized in that: include: A polymerization kettle (1) for mixing and preliminarily polymerizing raw materials of methyl methacrylate, comonomer, first initiator and chain transfer agent, wherein the polymerization kettle (1) is equipped with a paddle stirrer to ensure sufficient mixing and uniform reaction of the raw materials; A switch (2) for controlling the flow rate of the raw materials from the polymerization kettle (1) into the subsequent first reactor (3); A first reactor (3) is used for performing a preliminary reaction, mixing the material from the polymerization reactor with the first initiator and the second initiator, wherein the first reactor (3) is a static mixer structure to ensure the uniformity of the reaction; The second reactor (4) is used for further reaction. When a power outage or failure occurs, the reactor can be switched to inject toluene to terminate the reaction and avoid temperature runaway. The second reactor (4) is a static mixer structure; A tubular heat exchanger (5) is used to uniformly increase the temperature of the resin slurry in the second reactor (4), and is designed so that the resin passes through the tube layer and the heat transfer oil passes through the shell layer, so as to achieve more uniform heating and reduce the generation of carbides; The devolatilization extruder (6) is used to perform devolatilization treatment on the reacted resin slurry, thereby reducing residual monomers and improving the optical properties and product quality of the polymer.

2. A method for preparing a methyl methacrylate polymer, characterized in that: The method comprises the device as claimed in claim 1, wherein the method further comprises the following steps: S1, by weight, take 85-105 parts of methyl methacrylate, 12-24 parts of comonomer, 100×10 -4 ~200×10 -4 0.2-0.9 parts of chain transfer agent are mixed as raw materials, stirred evenly, and added into a polymerization kettle (1) for primary polymerization until the polymerization rate reaches 40%-60%, the primary polymerization temperature is 95-150° C., the pressure is 0.2-0.7 MPa, the time is 2-4 hours, and stirring is performed during the primary polymerization to obtain a primary polymerization material; S2, transferring the primary polymer material to the first reactor (3) through the switch (2), and adding 100×10 -4 ~200×10 -4 parts, second initiator 50×10 -4 ~80×10 -4 share; S3, heating the material after the primary polymerization and then inputting it into the second reactor (4) for secondary polymerization, wherein the inlet temperature of the second reactor (4) is 110-170° C., the outlet temperature is 140-190° C., and the polymerization rate of the material at the outlet is 70%-90%, thereby obtaining a secondary polymerization material; S4, inputting the secondary polymerization into a tubular heat exchanger (5) to uniformly increase the temperature of the resin slurry to obtain a uniform slurry; S5. The uniform slurry is input into a devolatilizing extruder (6) for devolatilization, wherein the devolatilization temperature is 190-270°C and the devolatilization pressure is 0.0001MPa-0.05MPa; the polymer output from the outlet of the devolatilizing extruder (6) is extruded to obtain a methyl methacrylate polymer product, wherein the extrusion temperature is 240-290°C; the temperature difference between the first initiator and the second initiator when the half-life is 1h is 40-60°C, and the half-life of the first initiator at the polymerization temperature of the primary polymerization is 10 seconds to 2 hours, and the half-life of the second initiator at the polymerization temperature of the secondary polymerization is 0.1 seconds to 1500 seconds, wherein the polymerization temperature of the secondary polymerization is the average value of the inlet temperature and the outlet temperature in the above step 2.

3. The method for preparing a methyl methacrylate polymer according to claim 2, characterized in that: The comonomer includes at least one of methyl methacrylate and methyl acrylate.

4. The method for preparing a methyl methacrylate polymer according to claim 2, characterized in that: The first initiator is at least one of 2,2'-azobis[N-(2-propenyl)-2-methylpropionamide], tert-butyl peroxyacetate, tert-amyl peroxybenzoic acid and tert-butyl peroxy 3,5,5-trimethylhexanoate; the second initiator is at least one of tert-butyl isopropyl peroxide, 1,1,3,3-tetramethylbutyl hydroperoxide, di-tert-butyl isopropyl peroxide, isopropyl hydroperoxide and di-tert-butyl peroxide.

5. The method for preparing a methyl methacrylate polymer according to claim 2, characterized in that: The half-life of the first initiator at the polymerization temperature of the primary polymerization is 30 seconds to 1 hour; the half-life of the second initiator at the polymerization temperature of the secondary polymerization is 1 second to 1000 seconds.

6. The method for preparing a methyl methacrylate polymer according to claim 2, characterized in that: The chain transfer agent is at least one of n-butyl mercaptan, isobutyl mercaptan, n-hexyl mercaptan, n-octyl mercaptan or n-dodecyl mercaptan.

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