Low-stress high-toughness PC-ABS modified plastic alloy material and preparation method thereof

Abstract

The invention relates to a low-stress high-toughness PC-ABS modified plastic alloy material and a preparation method thereof, and belongs to the technical field of plastic alloys. The material comprises PC resin, ABS resin, modified talcum powder, a block copolymer modifier and a toughening compatilizer. A segment A of the block copolymer modifier is epoxy group or carboxyl talc powder and PC resin, a segment C of the block copolymer modifier is compatible with an ABS resin matrix, and a segment B of the block copolymer modifier is a flexible chain to form a transition segment, so that stress is gently transferred from a rigid filler to a flexible matrix; and the toughening compatilizer adopts an epoxy functionalized core shell, the epoxy group reacts with the PC end group to reinforce the interface, and the butadiene rubber core absorbs impact energy, so that the problems of white marks and weld mark breakage of the injection molded part are further solved.

Description

Technical Field

[0001] The invention belongs to the technical field of plastic alloys and relates to a low-stress and high-toughness PC-ABS modified plastic alloy material and a preparation method thereof. Background Art

[0002] Plastic alloys are materials formed by physically mixing different polymers to combine the advantages of each component to enhance the material's performance and range of applications. Plastic alloys are widely used in modern industrial and consumer sectors, particularly in the automotive, electronics, and construction industries. One important type of plastic alloy is PC-ABS plastic alloy, which combines the excellent properties of polycarbonate (PC) and acrylonitrile-butadiene-styrene (ABS) resin. PC resin is known for its high transparency, high heat resistance, and good impact resistance, while ABS resin is widely used for its excellent processing properties and electrical insulation properties. By combining PC and ABS, PC-ABS plastic alloy is able to provide improved impact resistance, heat resistance, and processing properties, giving it significant advantages in applications requiring high-performance materials.

[0003] However, in many applications, especially in products subject to high loads or complex geometries, stress concentration and toughness of the material become significant factors affecting product performance and service life. Therefore, the production of low-stress, high-toughness PC-ABS modified plastic alloys has become particularly necessary. Low-stress materials can reduce the accumulation of internal stress during processing and use, thereby reducing the risk of cracking and deformation. This is crucial for applications where product appearance and structural integrity are paramount. High toughness means that the material can absorb more energy during impact, reducing the likelihood of breakage or failure. Low stress and high toughness can be achieved through careful selection and modification of raw materials, as well as optimized production processes.

[0004] Existing technologies still face some shortcomings when producing traditional PC-ABS plastic alloy materials. For example, traditional materials are often prone to breakage and white marks after injection molding, which is mainly caused by stress concentration and insufficient toughness of the material. During the injection molding process of complex structural parts or thin-walled parts, the internal stress of the material may cause the product to deform or crack, affecting its service life. In addition, the white mark problem not only affects the appearance of the product, but may also reflect poor toughness and stress distribution of the material. Therefore, the development of a low-stress, high-toughness PC-ABS modified plastic alloy material can significantly improve product quality and performance by optimizing the material formula and improving the production process, meeting the market demand for high-quality plastic alloy materials. Summary of the Invention

[0005] The purpose of the present invention is to provide a low-stress and high-toughness PC-ABS modified plastic alloy material and a preparation method thereof, so as to solve the problems of white marks and weld line fractures in PC-ABS material injection molded parts.

[0006] The purpose of the present invention can be achieved through the following technical solutions: A low-stress, high-toughness PC-ABS modified plastic alloy material comprises the following raw materials in parts by weight: 50-70 parts by weight of PC resin, 20-40 parts by weight of ABS resin, 5-15 parts by weight of modified talc, 0.5-3 parts by weight of a block copolymer modifier, and 2-8 parts by weight of a toughening compatibilizer. The block copolymer modifier comprises: a talc-philic segment A, which is a carboxyl group or an epoxy group; Segment B, derived from polycaprolactone or polyethylene glycol; a segment C of a polymeric matrix derived from polystyrene or polymethyl methacrylate; Wherein, the segment A and segment C are connected through segment B.

[0007] As a preferred technical solution of the present invention, the molecular weight of the polycaprolactone or polyethylene glycol is 1000-5000 g / mol.

[0008] As a preferred technical solution of the present invention, the preparation method of the block copolymer modifier comprises the following steps: A1, the monomer corresponding to the segment A is subjected to free radical polymerization initiated by a RAFT agent and azobisisobutyronitrile to generate a polymer chain transfer agent A; A2, using the macromolecular chain transfer agent A prepared in step A1 as an initiator, adding the corresponding monomer of chain B segment and a catalyst to form block AB; A3. Using the block AB prepared in step A2 as an initiator, add the C segment monomer and azobisisobutyronitrile to react to generate a block copolymer modifier.

[0009] As a preferred technical solution of the present invention, the A-segment monomer in step A1 is glycidyl methacrylate or acrylic acid; and the RAFT agent is 4-cyano-4-(phenylthiocarbonyl)pentanoic acid.

[0010] As a preferred technical solution of the present invention, the B-stage monomer in step A2 is ε-caprolactone or ethylene oxide; and the catalyst is stannous octoate.

[0011] As a preferred technical solution of the present invention, the C segment monomer in step A3 is styrene or methyl methacrylate.

[0012] In this application, the A segment in the block copolymer modifier contains epoxy or carboxyl groups that can hydrogen bond with the ester groups in the PC resin and the hydroxyl groups on the surface of talc powder. The C segment C styrene segment produces physical adsorption with the SAN in ABS through π-π interaction. The B segment acts as a flexible transition to further reduce the sudden stress of the filler and the collective.

[0013] As a preferred technical solution of the present invention, the preparation method of the modified talc is: talc powder, block copolymer modifier, and tetrabutylammonium bromide are heated to 160-180° C. under nitrogen protection and reacted for 10-30 minutes to obtain the modified talc.

[0014] As a preferred technical solution of the present invention, the preparation method of the toughening compatibilizer is: B1. Polymerizing butadiene, styrene, cross-linking agent divinylbenzene, and initiator potassium persulfate in an emulsifier solution to form a rubber core layer emulsion; B2, adding methyl methacrylate and glycidyl methacrylate to the core layer emulsion in sequence, and forming an epoxy functionalized shell layer under the action of tert-butyl hydroperoxide as an initiator; B3. After demulsification, washing and drying, toughening compatibilizer particles with a particle size of 100-300 nm are obtained.

[0015] As a preferred technical solution of the present invention, the weight ratio of butadiene, styrene, divinylbenzene, and potassium persulfate in step B1 is 50-70:30-45:1-3:0.3-0.8; the emulsifier solution contains 200-300 parts by weight of deionized water, 1.5-3 parts by weight of sodium lauryl sulfate, and 0.5-1 part by weight of nonylphenol polyoxyethylene ether; the mass ratio of the core layer emulsion, methyl methacrylate, glycidyl methacrylate, and tert-butyl hydroperoxide in step B2 is 100:40-60:5-15:0.1-0.3, and tert-butyl hydroperoxide is added in two times: the first time is mixed with the core layer emulsion before the addition of methyl methacrylate, accounting for 60% of the total amount, and the second time is mixed with glycidyl methacrylate and added dropwise, accounting for 40% of the total amount.

[0016] Furthermore, the method for preparing the low-stress and high-toughness PC-ABS modified plastic alloy material comprises the following steps: (1) Add PC resin, ABS resin and toughening compatibilizer into a high-speed mixer and mix at 60-80°C for 3-5 minutes to obtain a premix; (2) adding the premix prepared in step (1) into a twin-screw extruder, melt-blending at 190-220°C, and then adding modified talc powder; (3) dissolving the block copolymer modifier in acetone, adding the mixture into an extruder for blending, and devolatilizing the mixture under vacuum at 170-190° C. to obtain a solution; (4) The melt obtained in step (3) is extruded through a die, water-cooled, and pelletized to obtain plastic alloy particles.

[0017] Beneficial effects of the present invention: (1) The present invention significantly improves the stress distribution and toughness performance of the material by designing a block copolymer modifier with a specific structure. Specifically, the block copolymer consists of a talc-philic segment A, a flexible transition segment B, and a polymer matrix-philic segment C. The carboxyl or epoxy group of segment A can preferentially chemically bond with talc and the PC matrix, while the styrene segment of segment C produces electrostatic physical adsorption with the SAN in ABS through π-π interaction, achieving molecular-level interface enhancement. Segments A and C are connected by the flexible transition segment B as a stress buffer layer, which can effectively disperse impact stress.

[0018] (2) The present invention enhances the compatibility between PC and ABS and the overall toughness of the materials through a toughening compatibilizer. The toughening compatibilizer consists of a rubber core layer and an epoxy-functionalized shell layer. The cross-linked butadiene rubber core can induce multiple silver cracks upon impact and absorb energy through plastic deformation. The epoxy groups in the shell layer combine with the PC end groups (-OH) to enhance the interfacial bonding energy. DETAILED DESCRIPTION

[0019] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.

[0020] Example 1 A low-stress, high-toughness PC-ABS modified plastic alloy material comprises the following raw materials in parts by weight: 60 parts by weight of PC resin, 30 parts by weight of ABS resin, 10 parts by weight of modified talc, 1.7 parts by weight of a block copolymer modifier, and 5 parts by weight of a toughening compatibilizer; The block copolymer modifier comprises: a talc-philic segment A, which is a carboxyl group or an epoxy group; Segment B, derived from polycaprolactone or polyethylene glycol; a segment C of a polymeric matrix derived from polystyrene or polymethyl methacrylate; Wherein, the segment A and segment C are connected through segment B.

[0021] The polycaprolactone has a molecular weight of 1000-5000 g / mol.

[0022] The preparation method of the block copolymer modifier comprises the following steps: A1, the monomer corresponding to the segment A is subjected to free radical polymerization initiated by a RAFT agent and azobisisobutyronitrile to generate a polymer chain transfer agent A; A2, using the macromolecular chain transfer agent A prepared in step A1 as an initiator, adding the corresponding monomer of chain B segment and a catalyst and reacting at 100°C for 24 hours to form block AB; A3. Using the block AB prepared in step A2 as an initiator, add the C segment monomer and azobisisobutyronitrile to react to generate a block copolymer modifier.

[0023] In step A1, the segment A monomer is acrylic acid; the RAFT agent is 4-cyano-4-(phenylthiocarbonyl)pentanoic acid; the mass ratio of the segment A monomer, the RAFT agent, and azobisisobutyronitrile is 100:1:0.03; the free radical polymerization is carried out under nitrogen protection, the reaction temperature is 70° C., and the reaction time is 6 h.

[0024] In step A2, the segment B monomer is ε-caprolactone; the catalyst is stannous octoate; and the mass ratio of the macromolecular chain transfer agent A, segment B monomer, and catalyst is 1:2:0.015.

[0025] In step A3, the C segment monomer is styrene; the mass ratio of the block AB, the C segment monomer and azobisisobutyronitrile is 1:6:0.006.

[0026] The modified talc is prepared by mixing talc powder, a block copolymer modifier, and tetrabutylammonium bromide in a mass ratio of 100:13:0.5, heating the mixture to 170° C. under nitrogen protection, and reacting the mixture for 20 minutes.

[0027] The preparation method of the toughening compatibilizer is: B1. Mix butadiene, styrene, crosslinking agent divinylbenzene, and initiator potassium persulfate in an emulsifier solution and polymerize at 70°C for 8 hours to form a rubber core layer emulsion; B2. Methyl methacrylate and glycidyl methacrylate were sequentially added dropwise to the core layer emulsion, and the reaction was carried out at 75°C for 2.5 hours under the action of tert-butyl hydroperoxide to form an epoxy-functionalized shell layer. B3. Add 5% CaCl2 solution to break the emulsion, then wash and dry to obtain toughening compatibilizer particles with a particle size of 100-300 nm.

[0028] In step B1, the weight ratio of butadiene, styrene, divinylbenzene, and potassium persulfate is 60:40:2:0.5; the emulsifier solution contains 250 parts by weight of deionized water, 2 parts by weight of sodium lauryl sulfate, and 0.7 parts by weight of nonylphenol polyoxyethylene ether; in step B2, the mass ratio of the core layer emulsion, methyl methacrylate, glycidyl methacrylate, and tert-butyl hydroperoxide is 100:50:10:0.2, and tert-butyl hydroperoxide is added in two batches: the first batch is mixed with the core layer emulsion before the addition of methyl methacrylate, accounting for 60% of the total amount, and the second batch is mixed with glycidyl methacrylate and added dropwise, accounting for 40% of the total amount.

[0029] The method for preparing the low-stress and high-toughness PC-ABS modified plastic alloy material comprises the following steps: (1) Add PC resin, ABS resin and toughening compatibilizer into a high-speed mixer and mix at 70°C for 4 minutes to obtain a premix; (2) adding the premix prepared in step (1) into a twin-screw extruder, melt-blending at 200° C., and then adding modified talc powder; (3) dissolving the block copolymer modifier in acetone, adding the mixture into an extruder for blending, and devolatilizing the mixture under vacuum at 180°C to obtain a solution; (4) The melt obtained in step (3) is extruded through a die, water-cooled, and pelletized to obtain plastic alloy particles.

[0030] Example 2 A low-stress, high-toughness PC-ABS modified plastic alloy material comprises the following raw materials in parts by weight: 50 parts by weight of PC resin, 20 parts by weight of ABS resin, 5 parts by weight of modified talc powder, 0.5 parts by weight of a block copolymer modifier, and 2 parts by weight of a toughening compatibilizer; The block copolymer modifier comprises: a talc-philic segment A, which is a carboxyl group or an epoxy group; Segment B, derived from polycaprolactone or polyethylene glycol; a segment C of a polymeric matrix derived from polystyrene or polymethyl methacrylate; Wherein, the segment A and segment C are connected through segment B.

[0031] The polyethylene glycol has a molecular weight of 1000-5000 g / mol.

[0032] The preparation method of the block copolymer modifier comprises the following steps: A1, the monomer corresponding to the segment A is subjected to free radical polymerization initiated by a RAFT agent and azobisisobutyronitrile to generate a polymer chain transfer agent A; A2, using the macromolecular chain transfer agent A prepared in step A1 as an initiator, adding the corresponding monomer of chain B segment and a catalyst, and reacting at 80°C for 20 hours to form block AB; A3. Using the block AB prepared in step A2 as an initiator, add the C segment monomer and azobisisobutyronitrile to react to generate a block copolymer modifier.

[0033] In step A1, the segment A monomer is glycidyl methacrylate; the RAFT agent is 4-cyano-4-(phenylthiocarbonyl)pentanoic acid; the mass ratio of the segment A monomer, the RAFT agent, and azobisisobutyronitrile is 100:0.2:0.01; the free radical polymerization is carried out under nitrogen protection, the reaction temperature is 60° C., and the reaction time is 5 h.

[0034] In step A2, the B-stage monomer is ethylene oxide; the catalyst is stannous octoate; and the mass ratio of the macromolecular chain transfer agent A, the B-stage monomer, and the catalyst is 1:1.5:0.01.

[0035] In step A3, the C segment monomer is methyl methacrylate; the mass ratio of the block AB, the C segment monomer and azobisisobutyronitrile is 1:5:0.002.

[0036] The modified talc is prepared by mixing talc powder, a block copolymer modifier, and tetrabutylammonium bromide in a mass ratio of 100:5:0.1, heating the mixture to 160° C. under nitrogen protection, and reacting the mixture for 10 minutes.

[0037] The preparation method of the toughening compatibilizer is: B1. Mix butadiene, styrene, crosslinking agent divinylbenzene, and initiator potassium persulfate in an emulsifier solution and polymerize at 60°C for 7 hours to form a rubber core layer emulsion; B2. Methyl methacrylate and glycidyl methacrylate were sequentially added dropwise to the core layer emulsion, and the reaction was carried out at 70°C for 2 h under the action of tert-butyl hydroperoxide to form an epoxy-functionalized shell layer. B3. Add 5% CaCl2 solution to break the emulsion, then wash and dry to obtain toughening compatibilizer particles with a particle size of 100-300 nm.

[0038] In step B1, the weight ratio of butadiene, styrene, divinylbenzene, and potassium persulfate is 50:30:1:0.3; the emulsifier solution contains 200 parts by weight of deionized water, 1.5 parts by weight of sodium lauryl sulfate, and 0.5 parts by weight of nonylphenol polyoxyethylene ether; in step B2, the mass ratio of the core layer emulsion, methyl methacrylate, glycidyl methacrylate, and tert-butyl hydroperoxide is 100:40:5:0.1, and tert-butyl hydroperoxide is added in two batches: the first batch is mixed with the core layer emulsion before the addition of methyl methacrylate, accounting for 60% of the total amount, and the second batch is mixed with glycidyl methacrylate and added dropwise, accounting for 40% of the total amount.

[0039] The method for preparing the low-stress and high-toughness PC-ABS modified plastic alloy material comprises the following steps: (1) Add PC resin, ABS resin and toughening compatibilizer into a high-speed mixer and mix at 60°C for 3 minutes to obtain a premix; (2) adding the premix prepared in step (1) into a twin-screw extruder, melt-blending at 190° C., and then adding modified talc powder; (3) dissolving the block copolymer modifier in acetone, adding the mixture into an extruder for blending, and devolatilizing the mixture under vacuum at 170°C to obtain a solution; (4) The melt obtained in step (3) is extruded through a die, water-cooled, and pelletized to obtain plastic alloy particles.

[0040] Example 3 A low-stress, high-toughness PC-ABS modified plastic alloy material comprises the following raw materials in parts by weight: 70 parts by weight of PC resin, 40 parts by weight of ABS resin, 15 parts by weight of modified talc, 3 parts by weight of a block copolymer modifier, and 8 parts by weight of a toughening compatibilizer; The block copolymer modifier comprises: a talc-philic segment A, which is a carboxyl group or an epoxy group; Segment B, derived from polycaprolactone or polyethylene glycol; a segment C of a polymeric matrix derived from polystyrene or polymethyl methacrylate; Wherein, the segment A and segment C are connected through segment B.

[0041] The polycaprolactone has a molecular weight of 1000-5000 g / mol.

[0042] The preparation method of the block copolymer modifier comprises the following steps: A1, the monomer corresponding to the segment A is subjected to free radical polymerization initiated by a RAFT agent and azobisisobutyronitrile to generate a polymer chain transfer agent A; A2, using the macromolecular chain transfer agent A prepared in step A1 as an initiator, adding the corresponding monomer of chain B segment and a catalyst, and reacting at 120°C for 30 hours to form block AB; A3. Using the block AB prepared in step A2 as an initiator, add the C segment monomer and azobisisobutyronitrile to react to generate a block copolymer modifier.

[0043] In step A1, the segment A monomer is acrylic acid; the RAFT agent is 4-cyano-4-(phenylthiocarbonyl)pentanoic acid; the mass ratio of the segment A monomer, the RAFT agent, and azobisisobutyronitrile is 100:2:0.05; the free radical polymerization is carried out under nitrogen protection, the reaction temperature is 80° C., and the reaction time is 7 h.

[0044] In step A2, the segment B monomer is ε-caprolactone; the catalyst is stannous octoate; and the mass ratio of the macromolecular chain transfer agent A, segment B monomer, and catalyst is 1:1.5:0.02.

[0045] In step A3, the C segment monomer is styrene; the mass ratio of the block AB, the C segment monomer and azobisisobutyronitrile is 1:5:0.002.

[0046] The modified talc is prepared by mixing talc powder, a block copolymer modifier, and tetrabutylammonium bromide in a mass ratio of 100:20:1, heating the mixture to 180° C. under nitrogen protection, and reacting the mixture for 30 minutes.

[0047] The preparation method of the toughening compatibilizer is: B1. Mix butadiene, styrene, crosslinking agent divinylbenzene, and initiator potassium persulfate in an emulsifier solution and polymerize at 80°C for 9 hours to form a rubber core layer emulsion; B2. Methyl methacrylate and glycidyl methacrylate were sequentially added dropwise to the core layer emulsion, and the reaction was carried out at 80°C for 3 h under the action of tert-butyl hydroperoxide to form an epoxy-functionalized shell layer. B3. Add 5% CaCl2 solution to break the emulsion, then wash and dry to obtain toughening compatibilizer particles with a particle size of 100-300 nm.

[0048] In step B1, the weight ratio of butadiene, styrene, divinylbenzene, and potassium persulfate is 70:45:3:0.8; the emulsifier solution contains 300 parts by weight of deionized water, 3 parts by weight of sodium lauryl sulfate, and 1 part by weight of nonylphenol polyoxyethylene ether; in step B2, the mass ratio of the core layer emulsion, methyl methacrylate, glycidyl methacrylate, and tert-butyl hydroperoxide is 100:60:15:0.3, and tert-butyl hydroperoxide is added in two batches: the first batch is mixed with the core layer emulsion before the addition of methyl methacrylate, accounting for 60% of the total amount, and the second batch is mixed with glycidyl methacrylate and added dropwise, accounting for 40% of the total amount.

[0049] The method for preparing the low-stress and high-toughness PC-ABS modified plastic alloy material comprises the following steps: (1) Add PC resin, ABS resin and toughening compatibilizer into a high-speed mixer and mix at 80°C for 5 minutes to obtain a premix; (2) adding the premix prepared in step (1) into a twin-screw extruder, melt-blending at 220° C., and then adding modified talc powder; (3) dissolving the block copolymer modifier in acetone, adding the mixture into an extruder for blending, and devolatilizing the mixture under vacuum at 190°C to obtain a solution; (4) The melt obtained in step (3) is extruded through a die, water-cooled, and pelletized to obtain plastic alloy particles.

[0050] Comparative Example 1 On the basis of Example 1, the block copolymer modifier omitted the flexible connection of segment B, and the rest remained the same as Example 1.

[0051] Comparative Example 2 On the basis of Example 1, the talc powder was not modified, the block copolymer modifier and the talc powder were added separately, and the rest remained the same as Example 1.

[0052] Comparative Example 3 On the basis of Example 1, no toughening compatibilizer was added, and the rest remained the same as Example 1.

[0053] Comparative Example 4 On the basis of Example 1, the block copolymer modifier was replaced by silane coupling agent KH560, and the rest remained the same as Example 1.

[0054] Performance testing: Notched impact strength: The material's Izod notched impact strength is tested according to ASTM D256-2018 (23°C, V-notch). Environmental stress cracking: According to GB / T 11547-2008, the samples prepared in Examples and Comparative Examples were immersed in ethyl acetate and the cracking time was observed; Bending white mark test: 60 mm × 60 mm × 1 mm samples were made from the embodiment and the comparative example respectively, and then bent at 90° to observe whether there was white mark.

[0055] Notched impact strength (kJ / m²) Cracking time (min) 90° bend white print Example 1 68 ＞30 none Example 2 65 ＞30 none Example 3 62 ＞30 none Comparative Example 1 42 12 Obvious radial white marks Comparative Example 2 38 9 Severe white marks Comparative Example 3 48 21 Obvious white marks Comparative Example 4 45 4 Severe white marks From the above test results, it can be seen that the lack of B-segment flexible chain in comparative example 1 leads to sudden change in modulus and stress concentration; the unmodified talc powder interface in comparative example 2 is debonded, and stress concentration induces microcracks; the lack of rubber core in comparative example 3 causes silver streaks and concentrated stress with a large local density; comparative example 4 uses a traditional silane coupling agent with a small molecular weight (<500 g / mol), and cannot form a gradient interface layer.

[0056] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any indirect modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A low-stress, high-toughness PC-ABS modified plastic alloy material, characterized by: The invention comprises the following raw materials in parts by weight: 50-70 parts by weight of PC resin, 20-40 parts by weight of ABS resin, 5-15 parts by weight of modified talc powder, 0.5-3 parts by weight of block copolymer modifier, and 2-8 parts by weight of toughening compatibilizer; The block copolymer modifier comprises: a talc-philic segment A, which is a carboxyl group or an epoxy group; Segment B, derived from polycaprolactone or polyethylene glycol; a segment C of a polymeric matrix derived from polystyrene or polymethyl methacrylate; Wherein, the segment A and segment C are connected through segment B.

2. The low-stress, high-toughness PC-ABS modified plastic alloy material according to claim 1, characterized in that: The molecular weight of polycaprolactone or polyethylene glycol is 1000-5000 g / mol.

3. The low-stress, high-toughness PC-ABS modified plastic alloy material according to claim 1, characterized in that: The preparation method of the block copolymer modifier comprises the following steps: A1, the monomer corresponding to the segment A is subjected to free radical polymerization initiated by a RAFT agent and azobisisobutyronitrile to generate a polymer chain transfer agent A; A2, using the macromolecular chain transfer agent A prepared in step A1 as an initiator, adding the corresponding monomer of chain B segment and a catalyst to form block AB; A3. Using the block AB prepared in step A2 as an initiator, add the C segment monomer and azobisisobutyronitrile to react to generate a block copolymer modifier.

4. The low-stress, high-toughness PC-ABS modified plastic alloy material according to claim 3, characterized in that: In step A1, the monomer of segment A is glycidyl methacrylate or acrylic acid; and the RAFT agent is 4-cyano-4-(phenylthiocarbonyl)pentanoic acid.

5. The low-stress, high-toughness PC-ABS modified plastic alloy material according to claim 3, characterized in that: In step A2, the monomer of segment B is ε-caprolactone or ethylene oxide; and the catalyst is stannous octoate.

6. The low-stress, high-toughness PC-ABS modified plastic alloy material according to claim 3, characterized in that: The C-segment monomer in step A3 is styrene or methyl methacrylate.

7. The low-stress, high-toughness PC-ABS modified plastic alloy material according to claim 1, characterized in that: The preparation method of the modified talc is as follows: talc powder, a block copolymer modifier and tetrabutylammonium bromide are heated to 160-180° C. under nitrogen protection and reacted for 10-30 minutes to obtain the modified talc.

8. The low-stress, high-toughness PC-ABS modified plastic alloy material according to claim 1, characterized in that: The preparation method of the toughening compatibilizer is: B1. Polymerizing butadiene, styrene, cross-linking agent divinylbenzene, and initiator potassium persulfate in an emulsifier solution to form a rubber core layer emulsion; B2, adding methyl methacrylate and glycidyl methacrylate to the core layer emulsion in sequence, and forming an epoxy functionalized shell layer under the action of tert-butyl hydroperoxide as an initiator; B3. After demulsification, washing and drying, toughening compatibilizer particles with a particle size of 100-300 nm are obtained.

9. The low-stress, high-toughness PC-ABS modified plastic alloy material according to claim 8, characterized in that: In step B1, the weight ratio of butadiene, styrene, divinylbenzene, and potassium persulfate is 50-70:30-45:1-3:0.3-0.8; the emulsifier solution contains 200-300 parts by weight of deionized water, 1.5-3 parts by weight of sodium lauryl sulfate, and 0.5-1 part by weight of nonylphenol polyoxyethylene ether; in step B2, the weight ratio of the core layer emulsion, methyl methacrylate, glycidyl methacrylate, and tert-butyl hydroperoxide is 100:40-60:5-15:0.1-0.3, and tert-butyl hydroperoxide is added in two batches: the first batch is mixed with the core layer emulsion before the addition of methyl methacrylate, accounting for 60% of the total amount, and the second batch is mixed with glycidyl methacrylate and added dropwise, accounting for 40% of the total amount.

10. A method for preparing a low-stress, high-toughness PC-ABS modified plastic alloy material according to any one of claims 1 to 9, characterized in that: The following steps are involved: (1) Add PC resin, ABS resin and toughening compatibilizer into a high-speed mixer and mix at 60-80°C for 3-5 minutes to obtain a premix; (2) adding the premix prepared in step (1) into a twin-screw extruder, melt-blending at 190-220°C, and then adding modified talc powder; (3) dissolving the block copolymer modifier in acetone, adding the mixture into an extruder for blending, and devolatilizing the mixture under vacuum at 170-190° C. to obtain a solution; (4) The melt obtained in step (3) is extruded through a die, water-cooled, and pelletized to obtain plastic alloy particles.