Terpolymer heat-resistant agent as well as preparation method and application thereof

Abstract

The invention discloses a terpolymer heat-resistant agent as well as a preparation method and application thereof, and belongs to the technical field of high polymer material modifiers. Comprising the following raw materials in parts by weight: 100 parts of a monomer, 0.1-3.0 parts of a suspending agent, 0.5-2.0 parts of an initiator and 0.1-1.0 part of a chain transfer agent, the preparation method comprises the following steps: (1) weighing raw materials; (2) preparing a water phase; (3) preparing an organic phase; (4) suspension dispersion; (5) heating and polymerizing; and (6) post-treatment. According to the preparation method, a stable suspension system is formed by taking water as a continuous phase and silicon dioxide as a suspending agent, an initiator is added into an organic monomer phase, alpha-methylstyrene dimer is taken as a chain transfer agent, and terpolymer beads which are controllable in particle size, good in dispersity, high in glass transition temperature and adjustable in molecular weight are obtained through segmented heating polymerization. The obtained terpolymer can be used as a heat-resistant modifier of ABS, SAN, ASA, PVC and alloys thereof, the heat deformation temperature of the material is improved, the processing fluidity is considered, and the preparation method is simple in process, low in cost, convenient in post-treatment and suitable for large-scale production.

Description

A terpolymer heat-resistant agent, its preparation method and application Technical Field

[0001] This invention relates to the field of polymer material modifiers, and more specifically to a terpolymer heat-resistant agent, its preparation method, and its application. Background Technology

[0002] Acrylonitrile-butadiene-styrene resin (ABS), styrene-acrylonitrile copolymer (SAN), synthetic resin (ASA) made from styrene, acrylonitrile, and acrylate rubbers through graft copolymerization, and styrene-based resins such as polyvinyl chloride (PVC) possess good overall properties, but their heat resistance (e.g., heat distortion temperature) has room for improvement. Copolymers containing maleimide structural units typically have higher glass transition temperatures (Tg) and can be used as heat-resistant agents to improve the heat resistance of the matrix resin. Existing preparation methods are as follows:

[0003] The literature "N-Phenylamimide / Styrene / Acrylonitrile Emulsion Copolymer Blended with PVC" proposes an emulsion polymerization method to prepare terpolymers. However, this method requires processes such as emulsification, polymerization, and flocculation, which are lengthy and complex, and generate a large amount of wastewater that is difficult to treat, making it difficult to achieve industrialization.

[0004] Patent CN200710069041.6 reports a one-step suspension polymerization method for producing polystyrene-N-phenylmaleimide-acrylonitrile terpolymers. The terpolymer is obtained by adding a suspending agent, chain transfer agent, monomer, and initiator in one step and copolymerizing. The process is simple and easy to industrialize, but the glass transition temperature, heat distortion temperature, and Vicat softening temperature of the copolymer still need to be improved.

[0005] Patent CN104356272 A reported a micro-suspension polymerization method for styrene-N-phenylmaleimide-acrylonitrile, which yielded a terpolymer through polymerization, centrifugation, and drying. However, the cumbersome centrifugation process and low yield limited its industrialization.

[0006] Emulsion polymerization involves dispersing monomers in water to form an emulsion using emulsifiers and mechanical stirring, followed by the addition of an initiator to initiate polymerization. However, it faces challenges in industrialization due to its complex separation process, reactor clogging and potential for residues in the product, and the generation of large amounts of wastewater.

[0007] Suspension polymerization is a process in which monomers containing dissolved initiators are suspended in water as small droplets, and polymerization occurs through mechanical stirring and the action of a suspending agent. Each droplet represents a small unit of bulk polymerization, and the polymerization reaction takes place inside the droplet encapsulated by the suspending agent. Suspension agent residue is often present in the product, affecting the polymer's properties.

[0008] Therefore, how to prepare a novel terpolymer heat-resistant agent is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0009] In view of this, the purpose of the present invention is to provide a terpolymer heat-resistant agent, its preparation method and application, so as to overcome the shortcomings of the prior art.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: a terpolymer heat-resistant agent, comprising the following raw materials in parts by weight: 100 parts of monomer, 0.1-3.0 parts of suspending agent, 0.5-2.0 parts of initiator and 0.1-1.0 parts of chain transfer agent.

[0011] Furthermore, the monomers mentioned above include 30-70 parts of tert-butylstyrene, 15-30 parts of acrylonitrile, and 15-55 parts of N-phenylmaleimide.

[0012] Furthermore, the aforementioned suspending agent is at least one of hydrophilic silica and hydrophobic modified silica, with a particle size of 10-500 μm.

[0013] The further beneficial effects of employing the above-mentioned methods include the ability of silica to improve the heat resistance of polymers, with suspending agents and heat-resistant agents synergistically enhancing the heat resistance of the matrix resin during processing. Simultaneously, silica is also an environmentally friendly material, reducing the use of harmful solvents and meeting the requirements of sustainable development and green chemistry.

[0014] Furthermore, the initiator is an oil-soluble free radical initiator, preferably at least one of benzoyl peroxide, di-tert-butyl peroxide, lauroyl peroxide, azobisisobutyronitrile, and azobisisoheptanenitrile.

[0015] Furthermore, the aforementioned chain transfer agent is an α-methylstyrene dimer.

[0016] The further beneficial effects of the above-mentioned method are that the present invention uses a suspension polymerization route with silica as a suspending agent and α-methylstyrene dimer as a chain transfer agent: silica in the aqueous phase adsorbs at the interface to form a stable particulate suspension system; the chain transfer agent is added to the organic phase, and chain transfer occurs during the free radical polymerization chain growth process, reducing the risk of excessively high molecular weight and gelation, so that the product can maintain good flowability and processability while improving heat resistance.

[0017] A method for preparing a ternary copolymer heat-resistant agent includes the following steps: (1) Weighing raw materials according to the weight proportions of the above-mentioned ternary copolymer heat-resistant agent; (2) Preparing an aqueous phase by stirring and dispersing the suspending agent in water to obtain an aqueous phase; (3) Preparing an organic phase by mixing the monomer, initiator and chain transfer agent to obtain an organic phase; (4) Suspension and dispersion by adding the organic phase to the aqueous phase and forming a monomer droplet suspension system under stirring conditions, and introducing an inert gas to replace oxygen; (5) Heating polymerization by heating the monomer droplet suspension system to obtain a reaction system; (6) Post-treatment by cooling the reaction system and discharging it, separating the solid and liquid, washing with water, and drying to obtain the ternary copolymer heat-resistant agent.

[0018] To reduce the use of harmful solvents, this invention provides an environmentally friendly method for preparing a heat-resistant agent of tert-butylstyrene-N-phenylmaleimide-acrylonitrile terpolymer using suspension polymerization. This method achieves the following: 1. Stable reaction system, regular bead size, and easy filtration and washing; 2. Controllable molecular weight through α-methylstyrene dimer, improving processing fluidity; 3. Increased Tg through the structural units of N-phenylmaleimide and tert-butylstyrene.

[0019] 4. The method is simple to operate and easy to industrialize, which can reduce costs and improve production efficiency.

[0020] 5. Molecular weight can be controlled through α-methylstyrene dimer, improving processing fluidity and reducing product odor; 6. Tg can be increased through N-phenylmaleimide and tert-butylstyrene structural units.

[0021] Furthermore, in step (2) above, the amount of water used is 80-500 parts; the stirring speed is 100-800 rpm, preferably 200-400 rpm; and the stirring time is 20-40 min.

[0022] Furthermore, in step (4) above, the stirring speed is 200-400 rpm and the time is 10-30 min; the inert gas is nitrogen and the introduction time is 20-40 min.

[0023] Furthermore, in step (5) above, the temperature for heating polymerization is 40-120 ℃, the pressure is 0.05-0.2 MPa, the time is 3-8 h, and the reaction is carried out until the monomer conversion rate is ≥97%.

[0024] Furthermore, in step (6) above, the temperature for cooling and discharging is 30-50 ℃; the temperature for drying is 70-90 ℃.

[0025] The present invention also claims protection for the use of the above-described terpolymer heat resistant agent or the terpolymer heat resistant agent prepared by the above-described preparation method in the preparation of ABS, SAN, ASA, PVC and their alloys.

[0026] Furthermore, the aforementioned terpolymer heat-resistant agent is added to ABS, SAN, ASA, PVC and their alloys in the form of beads or powder, at a dosage of 5-30 wt%, to increase the heat distortion temperature and improve heat resistance.

[0027] As can be seen from the above technical solutions, compared with the prior art, the beneficial effects of the present invention are as follows: 1. Improved stability of suspended droplets, good dispersion of beads, and controllable particle size; 2. Adjustable molecular weight and melt rheology, reducing processing torque and melt fracture risk; 3. Higher Tg of terpolymer, which can significantly improve the heat distortion temperature of ABS, SAN, and ASA; 4. Simple process, the product can be obtained by washing and drying, suitable for continuous or batch scale-up.

[0028] In summary, this invention discloses a method for preparing a high-Tg terpolymer heat-resistant agent in a suspension polymerization system. This method utilizes silica to stabilize droplets and a chain transfer agent to precisely control the molecular weight. Water is used as the continuous phase, and silica as the suspending agent to form a stable suspension system. An initiator is added to the organic monomer phase, and α-methylstyrene dimer is used as the chain transfer agent. Through segmented heating polymerization, terpolymer beads with controllable particle size, good dispersibility, high glass transition temperature, and adjustable molecular weight are obtained. The resulting terpolymer can be used as a heat-resistant modifier for ABS, SAN, ASA, PVC, and their alloys, improving the material's heat distortion temperature while maintaining processing fluidity. Furthermore, the preparation method is simple, low-cost, and convenient for post-processing, making it suitable for large-scale production. Attached Figure Description

[0029] Figure 1 is a comparison of the glass transition temperatures of the tert-butylstyrene heat resistant agent of Example 2 and the styrene heat resistant agent of Comparative Example 3. Detailed Implementation

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] In the following examples, all raw materials, unless otherwise specified, are of industrial grade or analytical grade. All stirring was performed using mechanical stirring.

[0032] Example 1 (Typical Formulation) Ternary copolymer heat resistant agent, comprising the following raw materials by weight: 50 g tert-butylstyrene, 25 g acrylonitrile, 25 g N-phenylmaleimide, 1.2 g silica (1.2 wt% based on a total monomer content of 100 g), 0.6 g benzoyl oxide (0.6 wt%), and 0.8 g α-methylstyrene dimer (0.8 wt%); The preparation method of the above tergary copolymer heat resistant agent specifically includes the following steps: (1) Weighing raw materials: Weigh each raw material according to the weight of the above tergary copolymer heat resistant agent; (2) Preparing an aqueous phase: Add 300 g deionized water and 1.2 g silica (1.2 wt% based on a total monomer content of 100 g) to a 1 L stirred reactor, disperse at 200 rpm for 30 min to obtain an aqueous phase; (3) Preparing an organic phase: Add 50 g tert-butylstyrene, 25 g acrylonitrile, 25 g N-phenylmaleimide, and 1.2 g silica (1.2 wt% based on a total monomer content of 100 g), disperse at 200 rpm for 30 min to obtain an aqueous phase; (3) Mix and dissolve g, add 0.6 g (0.6 wt%) of benzoyl peroxide and 0.8 g (0.8 wt%) of α-methylstyrene dimer, mix well to obtain organic phase; (4) Suspension and dispersion: add organic phase to aqueous phase, stir at 300 rpm for 20 min to form monomer droplet suspension system, purge with nitrogen for 30 min to replace oxygen; (5) Heating and polymerization: first heat the monomer droplet suspension system to 65℃ and keep it at 1.5 h, then heat it to 85℃ and keep it at 1 h, and finally heat it to 105℃ and keep it at 1.5 h to obtain reaction system; (6) Post-treatment: after the reaction is terminated, cool the reaction system to 40℃ and discharge, filter, wash with water until the washing liquid has no obvious monomer odor, dry with hot air at 80℃ to constant weight to obtain white transparent / almost white transparent bead terpolymer heat resistant agent.

[0033] Example 2 (Improved heat resistance type) Ternary copolymer heat resistant agent, comprising the following raw materials by weight: 40 g tert-butylstyrene, 20 g acrylonitrile, 40 g N-phenylmaleimide, 1.5 g silica (1.5 wt% based on a total monomer content of 100 g), 0.75 g benzoyl oxide (0.75 wt%), and 1.0 g α-methylstyrene dimer (1.0 wt%). The preparation method of the above terpolymer heat resistant agent specifically includes the following steps: (1) Weighing raw materials: Weigh each raw material according to the weight of the above terpolymer heat resistant agent; (2) Preparing an aqueous phase: Add 300 g deionized water and 1.5 g silica (1.5 wt% based on a total monomer content of 100 g) to a 1 L stirred reactor, disperse at 200 rpm for 30 min to obtain an aqueous phase; (3) Preparing an organic phase: Add 40 g tert-butylstyrene, 20 g acrylonitrile, 40 g N-phenylmaleimide, and 1.5 g silica (1.5 wt% based on a total monomer content of 100 g) to a 1 L stirred reactor. (3) Mix and dissolve g, add 0.75 g (0.75 wt%) of benzoyl oxide and 1.0 g (1.0 wt%) of α-methylstyrene dimer, mix well to obtain organic phase; (4) Suspension and dispersion: add organic phase to aqueous phase, stir at 300 rpm for 20 min to form monomer droplet suspension system, purge with nitrogen for 30 min to replace oxygen; (5) Heating and polymerization: first heat the monomer droplet suspension system to 60 ℃ and react for 1.5 h, then heat to 70 ℃ and react for 1.5 h, then heat to 90 ℃ and react for 1.5 h, and finally heat to 105 ℃ and keep warm for 1.5 h to obtain reaction system; (6) Post-treatment: after the reaction is terminated, cool the reaction system to 40 ℃ and discharge, filter, wash with water until the washing liquid has no obvious monomer odor, dry with hot air at 80 ℃ to constant weight to obtain terpolymer heat-resistant agent beads with higher Tg, which are suitable for high heat-resistant ABS / SAN modification.

[0034] Example 3 (Improved Flowability Type) Ternary Copolymer Heat Resistance Agent, comprising the following raw materials by weight: 50 g tert-butylstyrene, 25 g acrylonitrile, 25 g N-phenylmaleimide, 1.2 g silica (1.2 wt% based on a total monomer content of 100 g), 0.75 g benzoyl oxide (0.6 wt%), and 1.8 g α-methylstyrene dimer (1.8 wt%). The preparation method of the above terpolymer heat resistance agent specifically includes the following steps: (1) Weighing the raw materials: Weigh each raw material according to the weight of the above terpolymer heat resistance agent; (2) Preparing the aqueous phase: Add 300 g deionized water and 1.2 g silica (1.2 wt% based on a total monomer content of 100 g) to a 1 L stirred reactor, disperse at 200 rpm for 30 min to obtain the aqueous phase; (3) Preparing the organic phase: Add 50 g tert-butylstyrene, 25 g acrylonitrile, 25 g N-phenylmaleimide, and 1.2 g silica (1.2 wt% based on a total monomer content of 100 g) to a 1 L stirred reactor. (3) Mix and dissolve g, add 0.75 g (0.6 wt%) of benzoyl oxide and 1.8 g (1.8 wt%) of α-methylstyrene dimer, mix well to obtain organic phase; (4) Suspension and dispersion: add organic phase to aqueous phase, stir at 300 rpm for 20 min to form monomer droplet suspension system, purge with nitrogen for 30 min to replace oxygen; (5) Heating and polymerization: first heat the monomer droplet suspension system to 65 ℃ and keep it at 1.5 h, then heat it to 85 ℃ and keep it at 1 h, then heat it to 105 ℃ and keep it at 1.5 h to obtain reaction system; (6) Post-treatment: after the reaction is terminated, cool the reaction system to 40 ℃ and discharge, filter, wash with water until the washing liquid has no obvious monomer odor, dry with hot air at 80 ℃ to constant weight to obtain terpolymer heat resistant agent with lower molecular weight and better processing fluidity, which is suitable for thin-wall injection molding application.

[0035] The only difference between Comparative Example 1 (without chain transfer agent) and Example 1 is that it does not contain α-methylstyrene dimer.

[0036] The results showed that the viscosity of the system increased more significantly in the later stage of polymerization, the beads were more likely to stick together, the resulting heat-resistant agent melt had poor fluidity, and the processing torque increased.

[0037] The only difference between Comparative Example 2 (without silica suspending agent) and Example 1 is that it does not contain silica.

[0038] The result is that the stability of monomer droplets deteriorates, and the polymer beads formed stick together, which is not conducive to cleaning and processing.

[0039] The only difference between Comparative Example 3 (styrene) and Example 2 is that tert-butylstyrene is replaced with styrene.

[0040] The results show that the glass transition temperature of the product obtained after polymerization is lower than that of the tert-butylstyrene copolymer, confirming that the introduction of tert-butylstyrene more effectively increases the glass transition temperature of the heat resistant agent by about 10 °C.

[0041] Performance Test 1. Heat Resistance Agent Test: The heat resistance agents obtained from Examples 1-3 and Comparative Examples 1-3 were tested for their Tg, molecular weight, heat distortion temperature and melt index, respectively.

[0042] The results are shown in Figure 1 and Table 1.

[0043] Table 1. Performance test results of the heat-resistant agents in Examples 1-3 and Comparative Examples 1-3

[0044] As shown in Figure 1 and Table 1, the heat resistance of the copolymer, such as the glass transition temperature and heat distortion temperature, increases with the increase of N-phenylmaleimide content. Compared with copolymerization of styrene with N-phenylmaleimide and acrylonitrile, the copolymer obtained by copolymerizing tert-butylstyrene with N-phenylmaleimide and acrylonitrile exhibits an approximately 6% increase in glass transition temperature and an approximately 5% increase in heat distortion temperature.

[0045] 2. Application test (as ABS heat resistant agent): The heat resistant agents obtained in Examples 1-2 and Comparative Example 3 were added to ABS resin at 15 wt% (twin-screw extrusion granulation), and ABS resin without added heat resistant agent was used as a blank control. Standard injection molded samples were tested.

[0046] The results are shown in Table 2.

[0047] Table 2 shows the performance test results of the ABS resin modified with heat resistant agent in Examples 1-2 and Comparative Example 3.

[0048] As can be seen from Table 2, the heat distortion temperature of the material is significantly increased after the addition of the heat resistant agent. The heat distortion temperature of the ABS resin modified with the heat resistant agent prepared by tert-butylstyrene is higher than that of the heat resistant agent prepared by styrene.

[0049] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A terpolymer heat-resistant agent, characterized in that, The raw materials include the following parts by weight: 100 parts monomer, 0.1-3.0 parts suspending agent, 0.5-2.0 parts initiator and 0.1-1.0 parts chain transfer agent.

2. The terpolymer heat resistant agent according to claim 1, characterized in that, The monomers include 30-70 parts of tert-butylstyrene, 15-30 parts of acrylonitrile, and 15-55 parts of N-phenylmaleimide.

3. The terpolymer heat-resistant agent according to claim 1, characterized in that, The suspending agent is at least one of hydrophilic silica and hydrophobic modified silica, with a particle size of 10-500 μm.

4. The terpolymer heat-resistant agent according to claim 1, characterized in that, The initiator is at least one selected from benzoyl peroxide, di-tert-butyl peroxide, lauroyl peroxide, azobisisobutyronitrile, and azobisisoheptanenitrile.

5. The terpolymer heat-resistant agent according to claim 1, characterized in that, The chain transfer agent is α-methylstyrene dimer.

6. A method for preparing a terpolymer heat-resistant agent, characterized in that, Specifically, the following steps are included: (1) Weigh the raw materials according to the weight parts of the terpolymer heat resistant agent according to any one of claims 1-5; (2) Prepare the aqueous phase by stirring and dispersing the suspending agent in water to obtain the aqueous phase; (3) Prepare the organic phase by mixing the monomer, initiator and chain transfer agent to obtain the organic phase; (4) Suspension and dispersion by adding the organic phase to the aqueous phase and forming a monomer droplet suspension system under stirring conditions, and passing inert gas to replace oxygen; (5) Heating and polymerization by heating the monomer droplet suspension system to obtain the reaction system; (6) Post-treatment by cooling the reaction system and discharging it, separating the solid and liquid, washing with water and drying to obtain the terpolymer heat resistant agent.

7. The method for preparing a terpolymer heat-resistant agent according to claim 6, characterized in that, In step (2), the amount of water used is 80-500 parts; the stirring speed is 100-800 rpm and the time is 20-40 min.

8. The method for preparing a terpolymer heat-resistant agent according to claim 6, characterized in that, In step (4), the stirring speed is 200-400 rpm and the time is 10-30 min; the inert gas is nitrogen and the introduction time is 20-40 min.

9. The method for preparing a terpolymer heat-resistant agent according to claim 6, characterized in that, In step (5), the heating polymerization temperature is 40-120 ℃, the pressure is 0.05-0.2 MPa, the time is 3-8 h, and the reaction is carried out until the monomer conversion rate is ≥97%; in step (6), the cooling discharge temperature is 30-50 ℃; and the drying temperature is 70-90 ℃.

10. The use of a terpolymer heat resistant agent as described in any one of claims 1-5 or a terpolymer heat resistant agent prepared by the preparation method as described in any one of claims 6-9 in the preparation of ABS, SAN, ASA, PVC and their alloys.

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