A method for preparing high impact ABS resin based on ontology process

Abstract

This invention proposes a method for preparing high-impact ABS resin based on a bulk polymerization process. The method includes: using styrene as the continuous phase medium, adding polybutadiene rubber to styrene and stirring to form a pre-dispersed rubber phase core; adding an initiator to the rubber dissolution product, heating and stirring to form graft copolymer segments; adding acrylonitrile to the prepolymerization product and stirring to form rubber phase particles during the copolymerization stage; adding a chain transfer agent to regulate free radical chain transfer, achieving a gradient distribution of acrylonitrile content from the core to the outer layer, constructing a multi-level interfacial structure with an energy dissipation gradient, and forming a tertiary multi-component copolymer system; subjecting the copolymerization product to vacuum devolatilization treatment, extrusion granulation, and obtaining high-impact ABS resin. This invention achieves a significant improvement in the impact resistance of ABS resin by precisely controlling the nanoscale dispersion of the rubber phase, the thickness of the graft layer, and the gradient of the shell composition.

Description

Technical Field

[0001] This invention belongs to the field of polymer material preparation technology, specifically relating to a bulk polymerization process based on dynamic phase morphology regulation. This process achieves nanoscale dispersion and interface enhancement of the rubber phase through multi-dimensional parameter synergistic control, thereby preparing ABS resin with excellent impact resistance. This is a method for preparing high-impact ABS resin based on a bulk polymerization process. Background Technology

[0002] As a typical multiphase polymer system, the impact resistance of ABS resin mainly depends on the dispersion state and interfacial interactions of the rubber phase in the SAN (styrene-acrylonitrile copolymer) continuous phase. In the traditional bulk preparation process, it is difficult to precisely control the dispersion uniformity and intermolecular bonding strength of the rubber phase, which makes the material prone to rubber phase detachment or crazing instability under impact loads, thus limiting its application in high-impact-resistant fields.

[0003] The existing technologies mainly suffer from the following technical bottlenecks: 1. The rubber phase has an uneven dispersion size, with an average particle size generally greater than 2 μm, making it impossible to form effective multiple craze induction centers; 2. The interfacial layer grafting density is insufficient (<0.2 chains / 100 nm). 2 1) This results in low stress transfer efficiency; 2) The acrylonitrile content distribution gradient is missing during copolymerization, making it difficult to construct a multi-level interface structure that dissipates energy; 3) The molecular weight distribution is wide (PDI>2.5), affecting the synergistic deformation ability of the matrix resin and the rubber phase.

[0004] Therefore, there is an urgent need to develop a novel preparation process that combines thermodynamically compatible system construction, free radical grafting regulation, and gradient copolymerization reaction engineering to break through the limitations of traditional technologies from the perspectives of phase morphology control and interface enhancement. Summary of the Invention

[0005] (a) Technical problems to be solved This invention proposes a method for preparing high-impact ABS resin based on a bulk process to solve the technical problems of uneven rubber phase dispersion and weak interfacial interaction. By precisely controlling the nanoscale dispersion of the rubber phase, the thickness of the graft layer, and the gradient of the shell composition, the impact resistance of ABS resin is significantly improved.

[0006] (II) Technical Solution To address the aforementioned technical problems, this invention proposes a method for preparing high-impact ABS resin based on a bulk process. This method includes the following steps: S1. Rubber dissolution Using styrene as the continuous phase medium, 8-15 parts by mass of polybutadiene rubber were added to 40-60 parts by mass of styrene. The swelling-dissolution equilibrium of the polybutadiene rubber was driven by stirring at a rate of 100-300 r / min within a temperature range of 50-70°C. The dissolution process satisfied the compatibility conditions of the Flory-Huggins thermodynamic equation. The solubility parameter difference between styrene and polybutadiene was controlled to be ≤3 (J / cm³). 3 ) 1 / 2 This forms a pre-dispersed rubber phase nucleus with an average particle size ≤500nm, ensuring the thermodynamically stable dispersion of the rubber phase in the continuous phase.

[0007] S2. Prepolymerization reaction Add 0.1-0.5 parts by weight of initiator to the rubber dissolution product. The initiator is benzoyl peroxide, cyclohexanone peroxide, or azobisisobutyronitrile initiator. Heat to 80-100℃ and control the nucleation rate of primary particles by stirring at a rate of 200-400 r / min. Utilize the matching relationship between the redox potential of the initiator and the electron cloud density of the styrene monomer to initiate a graft polymerization reaction on the surface of the rubber phase, forming graft copolymer segments (PS-g-PB) with a thickness of 50-100 nm and a grafting density of 0.3-0.8 chains / 100 nm. 2 The prepolymerization conversion rate is 20%~30%, and the grafted layer effectively reduces the interfacial tension in the subsequent copolymerization stage.

[0008] S3. Copolymerization reaction Add 15-25 parts by mass of acrylonitrile to the prepolymer product, heat to 100-120℃, and construct a shear-induced phase separation field by turbulent stirring at 300-500 r / min. The stirring Reynolds number Re = ρND. 2 / μ=10 4 ~10 5 By coupling the stirring Reynolds number with the reaction temperature, rubber phase particles with an average particle size of 1-3 μm are formed during the copolymerization stage. The addition of 0.05-0.2 parts by mass of n-octyl mercaptan as a chain transfer agent regulates free radical chain transfer, promoting the formation of a controllable thickness shell structure on the surface of the rubber core of the SAN continuous phase. This achieves a gradient distribution of acrylonitrile content from 15% in the core to 30% in the outer layer, constructing a multi-level interface structure with an energy dissipation gradient. Through the hydrogen abstraction reaction of sulfur radicals on the growing chain, the molecular weight distribution index (PDI) of the SAN copolymer is controlled at 1.8-2.2. This narrow distribution characteristic significantly improves the interfacial stress transfer efficiency between the matrix resin and the rubber phase. Finally, at a total conversion rate of 80%-90%, a multi-component copolymer system with a three-level structure of "core (PB)-shell (PS-g-PB)-layer (gradient SAN)" is formed.

[0009] S4. Post-processing The copolymerization product was subjected to devolatilization treatment at a temperature of 180~200℃, a vacuum degree of ≤10kPa, and extrusion granulation at a screw speed of 200~300r / min to obtain high-impact ABS resin.

[0010] Furthermore, in step S2, 0.05 to 0.2 parts by mass of 2,6-di-tert-butyl-p-cresol, acting as an antioxidant, are added simultaneously with the initiator decomposition kinetics. By utilizing the synergistic effect of the antioxidant and the initiator decomposition kinetics, the autoxidation side reaction of styrene monomer is suppressed, ensuring that the conjugated double bond retention rate is ≥95%, thus guaranteeing the effective progress of the subsequent grafting reaction.

[0011] Furthermore, this invention proposes a high-impact ABS resin in which the copolymer glass transition temperature (Tg) detected by DSC exhibits a dual-modal distribution: the rubber phase region Tg is -80 to -70°C, and the SAN continuous phase region Tg is 100 to 110°C. The temperature difference between the two ensures that the material exhibits a synergistic toughening effect of multiple crazing and shear bands under impact loads.

[0012] (III) Beneficial Effects This invention proposes a method for preparing high-impact ABS resin based on a bulk polymerization process. The method includes: using styrene as the continuous phase medium, adding polybutadiene rubber to styrene and stirring to form a pre-dispersed rubber phase core; adding an initiator to the rubber dissolution product, heating and stirring to form graft copolymer segments; adding acrylonitrile to the prepolymerization product and stirring to form rubber phase particles during the copolymerization stage; adding a chain transfer agent to regulate free radical chain transfer, achieving a gradient distribution of acrylonitrile content from the core to the outer layer, constructing a multi-level interfacial structure with an energy dissipation gradient, and forming a tertiary multi-component copolymer system; subjecting the copolymerization product to vacuum devolatilization treatment, extrusion granulation, and obtaining high-impact ABS resin. This invention achieves a significant improvement in the impact resistance of ABS resin by precisely controlling the nanoscale dispersion of the rubber phase, the thickness of the graft layer, and the gradient of the shell composition.

[0013] The present invention has the following beneficial effects: 1. Nanoscale phase dispersion: Through the construction of a thermodynamically compatible system, uniform dispersion of rubber phase nuclei (average particle size ≤500nm) is achieved, providing sufficient sites for the induction of multiple crazes; 2. Interface enhancement effect: The formation of controllable grafted layers (50~100nm) and gradient SAN shells reduces interfacial tension by 30%-40% and improves stress transfer efficiency by more than 45%. 3. Energy dissipation mechanism: The dual-mode glass transition temperature (rubber phase Tg=-80~-70℃, SAN phase Tg=100~110℃) promotes the synergistic toughening of crazing and shear bands under impact load, which improves the impact strength by 40%~60% compared with the traditional process; 4. Optimized molecular weight distribution: Narrow distribution SAN (PDI=1.8~2.2) can significantly improve the synergistic deformation ability of the matrix and rubber phase, and avoid brittle fracture caused by stress concentration. Detailed Implementation

[0014] To make the objectives, contents, and advantages of the present invention clearer, the specific embodiments of the present invention will be described in further detail below with reference to examples.

[0015] Example 1 Raw material composition (parts by weight): styrene 50, acrylonitrile 20, polybutadiene rubber 10, benzoyl peroxide 0.3, 2,6-di-tert-butyl-p-cresol 0.1, n-octyl mercaptan 0.1.

[0016] Preparation steps 1. Rubber dissolution: Polybutadiene rubber was added to styrene and stirred at 200 r / min for 1.5 h at 60 °C. The solubility parameter difference Δδ was measured to be 2.8 (J / cm³). 3 ) 1 / 2 This forms a rubber phase nucleus with an average particle size of 450 nm; 2. Prepolymerization reaction: Add benzoyl peroxide and 2,6-di-tert-butyl-p-cresol, heat to 90℃, stir at 300 rpm for 2 h, and graft at a density of 0.5 chains / 100 nm. 2 Conversion rate 25%; 3. Copolymerization reaction: Add acrylonitrile, heat to 110℃, stir at 400 r / min for 4 h, Reynolds number Re = 1.2 × 10⁻⁶ 5 The amount of n-octyl mercaptan used resulted in a PDI of 2.1 for SAN, and the acrylonitrile content in the SAN shell gradually increased from 18% in the core to 28% in the outer layer, with a total conversion rate of 85%. 4. Post-treatment: Vacuum devolatilization at 190℃ for 30 min, followed by extrusion granulation (screw speed 250 r / min).

[0017] Performance testing SEM observation: The average particle size of the rubber phase is 1.2 μm, and the shell thickness is 80 nm; DSC detection: The two Tg peaks were -75℃ and 105℃, respectively; Interfacial tension: 14 mN / m (17~20 mN / m for traditional processes); The density of silver crazing increased by 1.6 times compared to traditional samples; Impact strength of cantilever beam: 39kJ / m² (23℃, GB / T 1843-2008).

[0018] Example 2 Raw material composition (parts by weight): styrene 46, acrylonitrile 22, polybutadiene rubber 12, azobisisobutyronitrile 0.4, antioxidant 0.15, n-octyl mercaptan 0.15.

[0019] Key parameter control The stirring speed during the copolymerization stage was 500 r / min, and Re = 1.5 × 10⁻⁶. 5 Grafting density: 0.7 chains / 100nm 2 The amount of n-octyl mercaptan used makes the PDI of SAN = 1.9, forming an acrylonitrile content gradient (15% in the core → 30% in the outer layer).

[0020] Performance indicators SEM observation: The average particle size of the rubber phase is 1.1 μm, and the shell thickness is 74 nm; DSC detection: The two Tg peaks were -74℃ and 106℃, respectively; Interfacial tension: 12mN / m (17~20mN / m for traditional processes); The density of silver crazing is twice that of traditional samples; Impact strength of cantilever beam: 42kJ / m 2 (23℃, GB / T 1843-2008).

[0021] Comparison – Traditional Ontology Approach Process parameters: The rubber dissolution temperature is 75℃, and the solubility parameter is not controlled. There is no stirring speed control during the prepolymerization stage, and the grafting density is 0.15 chains / 100nm. 2 ; Acrylonitrile is added in one step during the copolymerization stage, without gradient distribution.

[0022] Performance comparison: The average particle size of the rubber phase is 2 μm, and the interfacial tension is 18 mN / m. Impact strength 18~25kJ / m 2 The DSC showed only a single Tg peak (95℃).

[0023] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing high-impact ABS resin based on a bulk process, characterized in that, The method for preparing high-impact ABS resin based on bulk process includes the following steps: S1. Rubber dissolution Using styrene as the continuous phase medium, polybutadiene rubber is added to styrene, stirred, and the solubility parameter difference between styrene and polybutadiene is controlled to form a pre-dispersed rubber phase nucleus; S2. Prepolymerization reaction An initiator is added to the rubber dissolution product, and the mixture is heated and stirred to form graft copolymer segments; S3. Copolymerization reaction Acrylonitrile is added to the prepolymer product and stirred to form rubber phase particles during the copolymerization stage. Chain transfer agent is added to regulate the free radical chain transfer, which promotes the formation of a shell structure with controllable thickness on the surface of the rubber core of the SAN continuous phase, realizes the gradient distribution of acrylonitrile content from the core to the outer layer, constructs a multi-level interface structure with energy dissipation gradient, and forms a tertiary multi-component copolymer system. S4. Post-processing The copolymerization product was subjected to vacuum devolatilization and extrusion granulation to obtain high-impact ABS resin.

2. The method for preparing high-impact ABS resin based on the bulk process as described in claim 1, characterized in that, Step S1 specifically includes: using styrene as the continuous phase medium, adding 8-15 parts by mass of polybutadiene rubber to 40-60 parts by mass of styrene; driving the swelling-dissolution equilibrium of the polybutadiene rubber at a stirring rate of 100-300 r / min within a temperature range of 50-70℃; and controlling the solubility parameter difference between styrene and polybutadiene Δδ≤3 (J / cm³). 3 ) 1 / 2 This forms a pre-dispersed rubber phase nucleus with an average particle size ≤500nm.

3. The method for preparing high-impact ABS resin based on the bulk process as described in claim 1, characterized in that, Step S2 specifically includes: adding 0.1~0.5 parts by weight of initiator to the rubber dissolution product, heating to 80~100℃, controlling the nucleation rate of primary particles by stirring at a rate of 200~400 r / min, initiating a graft polymerization reaction on the surface of the rubber phase to form graft copolymer segments with a thickness of 50~100 nm and a grafting density of 0.3~0.8 chains / 100 nm. 2 The prepolymer conversion rate is 20%~30%.

4. The method for preparing high-impact ABS resin based on the bulk process as described in claim 3, characterized in that, The initiator is benzoyl peroxide, cyclohexanone peroxide, or azobisisobutyronitrile initiator.

5. The method for preparing high-impact ABS resin based on the bulk process as described in claim 1, characterized in that, Step S3 specifically includes: adding 15-25 parts by mass of acrylonitrile to the prepolymer product, heating to 100-120℃, and constructing a shear-induced phase separation field by turbulent stirring at 300-500 r / min, with a stirring Reynolds number Re=ρND. 2 / μ=10 4 ~10 5 By coupling the stirring Reynolds number with the reaction temperature, rubber phase particles with an average particle size of 1~3μm are formed in the copolymerization stage; the addition of 0.05~0.2 parts by mass of chain transfer agent regulates the free radical chain transfer, causing the SAN continuous phase to form a shell structure with controllable thickness on the surface of the rubber core, achieving a gradient distribution of acrylonitrile content from 15% in the core to 30% in the outer layer, and constructing a multi-level interface structure with energy dissipation gradient; the molecular weight distribution index of the SAN copolymer is controlled at 1.8~2.2; at a total conversion rate of 80%~90%, a tertiary multi-component copolymer system is formed.

6. The method for preparing high-impact ABS resin based on the bulk process as described in claim 5, characterized in that, The chain transfer agent is n-octylthiol.

7. The method for preparing high-impact ABS resin based on the bulk process as described in claim 1, characterized in that, Step S4 specifically includes: performing devolatilization treatment at a temperature of 180~200℃, vacuum degree ≤10kPa, extrusion granulation, screw speed of 200~300r / min, to obtain high impact ABS resin.

8. The method for preparing high-impact ABS resin based on the bulk process as described in claim 1, characterized in that, In step S2, 0.05-0.2 parts by mass of 2,6-di-tert-butyl-p-cresol, acting as an antioxidant, are added simultaneously with the initiator decomposition kinetics. By utilizing the synergistic effect of the antioxidant and the initiator decomposition kinetics, the autoxidation side reaction of styrene monomer is suppressed, ensuring that the conjugated double bond retention rate is ≥95%, thus guaranteeing the effective progress of the subsequent grafting reaction.

9. A high-impact ABS resin, characterized in that, The high-impact ABS resin prepared by any one of claims 1 to 8 exhibits a bimodal distribution of copolymer glass transition temperature (Tg) as detected by DSC, with the rubber phase region Tg being -80 to -70°C and the SAN continuous phase region Tg being 100 to 110°C.