Low-shrinkage PA-ABS alloy material and preparation method thereof

Abstract

The invention discloses a low-shrinkage PA-ABS (polyamide-acrylonitrile-butadiene-styrene) alloy material and a preparation method thereof, the composition is prepared from the following components in parts by mass: 35-48 parts of polyhexamethylene adipamide matrix resin and 5-12 parts of polycaprolactam matrix resin; 25 to 38 parts of an acrylonitrile-butadiene-styrene copolymer; 3 to 6 parts of an ethylene-ethyl acrylate-maleic anhydride (E-EA-MAH) terpolymer; 0.8 to 2.2 parts of composite reinforcing filler; 0.3 to 0.9 part of a light stabilizer bis [2, 2, 6, 6-tetramethyl-4-piperidyl] sebacate; 0.1 to 0.5 part of a release agent ethylene bis stearamide; and 1.2 to 2.8 parts of an interface compatibilizer. According to the invention, through multi-component collaborative design and interface engineering regulation and control, a multi-layer interaction network is constructed, a terpolymer containing an epoxy group and a block structure compatibilizer are further introduced, interface reaction and energy dissipation between PA and ABS are promoted, and through nanoscale gradient interface design of a release agent and a filler, the release agent and the filler are combined, so that the release agent and the filler are combined, and the release agent and the filler are combined. And the interface friction and residual stress in the forming process are obviously reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of PA-ABS alloy materials, and specifically relates to a PA-ABS alloy material with low shrinkage; in particular, it also relates to a preparation method of the PA-ABS alloy material with low shrinkage. Background Art

[0002] PA-ABS alloys are polymer alloys made by physically blending or reactively expanding polyamide (PA) and acrylonitrile-butadiene-styrene (ABS) copolymers. They are widely used in automotive parts, electronic and electrical housings, and other fields. Polyamide and acrylonitrile-butadiene-styrene (ABS) alloys combine the high strength and heat resistance of PA with the processing fluidity of ABS, making them a research hotspot in the engineering plastics field. However, traditional PA-ABS materials suffer from significant drawbacks during the molding process: due to the polarity difference between PA and ABS (PA contains highly polar amide groups, while the butadiene phase in ABS is non-polar), the two components exhibit poor compatibility, leading to weak interfacial bonding and a high volumetric shrinkage (typically ≥0.8%) during cooling after injection molding. This directly impacts the dimensional accuracy and surface finish of the finished part. Furthermore, issues such as uneven dispersion of reinforcing fillers and interfacial stress concentration further exacerbate material shrinkage, limiting its application in precision molding.

[0003] In the existing technology, the main methods for improving the shrinkage rate of PA-ABS include the following two categories: first, promoting the compatibility of the two phases by adding a compatibilizer; second, introducing inorganic fillers to enhance dimensional stability. However, conventional fiber reinforcement will significantly increase the melt viscosity, aggravating molecular orientation during injection molding, which in turn causes anisotropic shrinkage. In addition, the microcracks at the interface between the fiber and the matrix will become stress concentration points, which can easily lead to a decline in mechanical properties after long-term use.

[0004] To address these issues, the industry has begun exploring solutions that combine composite compatibilization with multi-scale reinforcement. For example, nano-montmorillonite is blended with PA6 / ABS. While the montmorillonite's lamellar structure can restrict molecular chain motion, its interfacial bonding with the PA matrix relies on simple physical adsorption, and insufficient control of interlayer spacing limits the reinforcement effect. Furthermore, the polar group content and distribution of the terpolymer, acting as a compatibilizer, are difficult to precisely control, and the synergistic interaction mechanism with the reinforcing filler is not considered. Summary of the Invention

[0005] The present invention aims to provide a low-shrinkage PA-ABS alloy material and a preparation method thereof. Through multi-component collaborative design and interface engineering regulation, a multi-level interaction network is constructed. Furthermore, an epoxy-group-containing terpolymer and a block structure compatibilizer are introduced to promote interfacial reaction and energy dissipation between the PA and ABS phases. Finally, through the nanoscale gradient interface design of the release agent and filler, interfacial friction and residual stress during the molding process are significantly reduced.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A low shrinkage PA-ABS alloy material, the composition consisting of the following components in parts by mass:

[0008] 35-48 parts of polyhexamethylene adipamide matrix resin, 5-12 parts of polycaprolactam matrix resin; 25-38 parts of acrylonitrile-butadiene-styrene copolymer; 3-6 parts of ethylene-ethyl acrylate-maleic anhydride (E-EA-MAH) terpolymer; 0.8-2.2 parts of composite reinforcing filler; 0.3-0.9 parts of light stabilizer bis[2,2,6,6-tetramethyl-4-piperidinyl]sebacate; 0.1-0.5 parts of ethylene bisstearamide as a release agent; and 1.2-2.8 parts of an interfacial compatibilizer.

[0009] Preferably, the composite reinforcing filler is a glass fiber surface-treated with γ-aminopropyltrimethoxysilane and an organically modified nano-montmorillonite compounded in a mass ratio of (18-25):1, and its molecular structure contains chemically bonded Si-OC segments. The average diameter of the glass fiber is 9.6-12.8 μm, and the aspect ratio is controlled between 45:1 and 68:1; the interlayer spacing of the organically modified nano-montmorillonite is determined to be 4.3-5.2 nm by X-ray diffraction, and the surface of its crystal particles is grafted with an organic long-chain alkyl with the chemical formula CH2CHCOO(CH2)17CH3.

[0010] Preferably, the weight average molecular weight of the polyhexamethylene adipamide matrix resin is 3.5×10 4 -4.8×10 4 g / mol, the amide group content in its molecular chain is 86-92 mol%, and the molar ratio with the polycaprolactam matrix resin is strictly maintained at 1:(0.12-0.25); the terminal carboxyl group content of the polycaprolactam matrix resin is in the range of 34-52 mmol / kg, and the intrinsic viscosity thereof measured at 25°C is 2.3-3.1 dL / g.

[0011] Preferably, the molar percentages of the three monomers in the ethylene-ethyl acrylate-maleic anhydride terpolymer are ethylene:ethyl acrylate:maleic anhydride 55-68%:25-32%:7-13%, and its main chain structure contains alternating repeating units of -CH2-CH2-, -CH2-CH(OCOCH2CH3)- and -CH2-CH(COOH)- generated by free radical polymerization, and each molecular chain contains an average of 5-8 glycidyl grafting points.

[0012] Preferably, the interfacial compatibilizer is a block copolymer formed by reacting styrene-maleic anhydride copolymer with double-terminated carboxyl polybutadiene in a molar ratio of 3:1-5:1, and its molecular structure is:

[0013] -[St-alt-MAn]-b-[(HOOC(CH2)3COO)0.5-PB-(OOC(CH2)3COOH)0.5]-;

[0014] Wherein, St represents a styrene monomer unit, MAn represents a maleic anhydride monomer unit, and PB represents a polybutadiene segment; the pH value (AN) of the compatibilizer is between 95-115 mgKOH / g.

[0015] Preferably, a gradient interface layer is formed between the release agent ethylene bisstearamide and the composite reinforcing filler. The thickness of the gradient interface layer is 8-15 nm as measured by atomic force microscopy, and the gradient interface layer comprises a periodic layered structure assembled by intermolecular forces, and its constituent units conform to the following general formula:

[0016] [(CH2)2{NHC(O)(CH2)16CH3}2]·(SiO3^(2-))n·[Al(OH)4]-;

[0017] In the formula, SiO3^2- comes from the deprotonation of the surface silanol groups of the composite reinforcing filler, and Al(OH)4 comes from the lamellar cations of the organically modified nano-montmorillonite.

[0018] A method for preparing a low-shrinkage PA-ABS alloy material, the method being used to prepare the above-mentioned low-shrinkage PA-ABS alloy material, comprising the following steps:

[0019] S1, drying pretreatment;

[0020] S2. Surface treatment and compounding of reinforcing fillers;

[0021] S3, synthesis of interfacial compatibilizer;

[0022] S4, melt blending processing;

[0023] S5, molding and post-processing.

[0024] Preferably, step S1 specifically comprises: placing the polyhexamethylene adipamide matrix resin, the polycaprolactam matrix resin and the acrylonitrile-butadiene-styrene copolymer in a vacuum oven, controlling the temperature in the range of 85-95° C. and vacuum drying for 8-12 hours to make the moisture content lower than 0.03%; at the same time, drying the composite reinforcing filler at 120-135° C. for 4-6 hours to avoid residual water molecules on the interface during subsequent processing; after drying, all raw materials are transferred to a mixing bin under a nitrogen protection environment;

[0025] Step S2 is specifically as follows:

[0026] The glass fiber is treated with a hydrolyzed solution of γ-aminopropyltrimethoxysilane having a concentration of 3.5-5.2 wt% for 30-45 minutes at a temperature of 55-65°C, and then centrifuged and dried. The organically modified nano-montmorillonite and the treated glass fiber are placed in an ultrasonic disperser at a mass ratio of (18-25):1 and blended for 15-20 minutes at a frequency of 40 kHz and a power of 600 W to form a composite reinforcing filler with Si-OC chemical bonds.

[0027] Preferably, step S3 is specifically as follows: styrene-maleic anhydride copolymer (number average molecular weight 8000-12000 g / mol) and double-end carboxyl polybutadiene (carboxyl content 3.6-4.2 mmol / g) are added to the reactor in a molar ratio of 3:1-5:1, melt blended at 220-240 ° C under nitrogen protection, and 0.05-0.1% by mass of azobisisobutyronitrile (AIBN) is added as an initiator, and the reaction is carried out for 2-3 hours to obtain a block copolymer interfacial compatibilizer.

[0028] The technical effects and advantages of the present invention are as follows:

[0029] By compounding poly(hexamethylene adipamide) and poly(caprolactam) and controlling their molecular weight, a high-entanglement-density mixed matrix network is formed. Combined with the interfacial bridging effect of the styrene-maleic anhydride block copolymer compatibilizer, the compatibility between the PA and ABS phases is significantly enhanced. During injection molding, the molecular chain relaxation is increased, anisotropic shrinkage during cooling is reduced, and the shrinkage of the finished product is reduced.

[0030] Bis[2,2,6,6-tetramethyl-4-piperidinyl] sebacate is preferentially anchored in the butadiene phase of ABS through intermolecular hydrogen bonds with a binding energy of -18.6 to -23.4 kJ / mol, forming evenly distributed stable units. After UV-accelerated aging testing, the material's yellowing index decreases. At the same time, the glycidyl groups in the terpolymer E-EA-MAH react with the terminal amino groups of PA to generate crosslinking points that inhibit photooxidative breakage of the molecular chain and improve impact strength retention. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the embodiments described are only a part of the embodiments of the present invention, not all of the embodiments. The specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0032] The present invention proposes a low-shrinkage PA-ABS alloy material. Through multi-component collaborative design and interface engineering regulation, a multi-level interaction network is constructed. A ternary copolymer containing epoxy groups and a block structure compatibilizer are further introduced to promote the interfacial reaction and energy dissipation between the PA and ABS phases. Finally, through the nanoscale gradient interface design of the release agent and filler, the interfacial friction and residual stress during the molding process are significantly reduced.

[0033] The composition consists of the following components:

[0034] Polyhexamethylene adipamide matrix resin, polycaprolactam matrix resin, acrylonitrile-butadiene-styrene copolymer, ethylene-ethyl acrylate-maleic anhydride (E-EA-MAH) terpolymer, composite reinforcing filler, light stabilizer bis[2,2,6,6-tetramethyl-4-piperidinyl] sebacate, release agent ethylene bisstearamide, interface compatibilizer.

[0035] The preparation method of the above-mentioned low shrinkage PA-ABS alloy material is as follows:

[0036] S1, drying pretreatment; Step S1 specifically comprises: placing the polyhexamethylene adipamide matrix resin, the polycaprolactam matrix resin and the acrylonitrile-butadiene-styrene copolymer in a vacuum oven, controlling the temperature in the range of 85-95°C for vacuum drying for 8-12 hours to make the moisture content less than 0.03%; at the same time, drying the composite reinforcing filler at 120-135°C for 4-6 hours to avoid residual interfacial water molecules in subsequent processing. After drying, all raw materials are transferred to a mixing bin under a nitrogen protection environment.

[0037] S2. Surface treatment and compounding of reinforcing fillers: treating the glass fiber with a hydrolyzed solution of γ-aminopropyltrimethoxysilane having a concentration of 3.5-5.2 wt% for 30-45 minutes at a treatment temperature of 55-65°C, followed by centrifugal separation and drying; placing the organically modified nano-montmorillonite and the treated glass fiber in an ultrasonic disperser at a mass ratio of (18-25):1, and blending them at a frequency of 40 kHz and a power of 600 W for 15-20 minutes to form a composite reinforcing filler having Si-OC chemical bonds.

[0038] S3, synthesis of an interfacial compatibilizer; Step S3 specifically comprises: adding styrene-maleic anhydride copolymer (number average molecular weight 8000-12000 g / mol) and double-end carboxyl polybutadiene (carboxyl content 3.6-4.2 mmol / g) into a reactor at a molar ratio of 3:1-5:1, melt-blending at 220-240° C. under nitrogen protection, and adding 0.05-0.1% by weight of azobisisobutyronitrile (AIBN) as an initiator, and reacting for 2-3 hours to obtain a block copolymer interfacial compatibilizer.

[0039] S4. Melt blending process: The melt blending process is carried out using conventional technologies and equipment in the existing industry, which will not be described in detail here.

[0040] S5: Molding and post-processing: pelletizing or making linear materials according to needs, and then packaging and storage.

[0041] Example 1

[0042] Component ratio (parts by mass):

[0043] Polyhexamethylene adipamide matrix resin: 42 parts (Mw = 4.2 × 10 4 g / mol, amide group content 89 mol%);

[0044] Polycaprolactam matrix resin: 8 parts (terminal carboxyl content 42 mmol / kg, intrinsic viscosity 2.8 dL / g);

[0045] ABS: 32 copies;

[0046] E-EA-MAH terpolymer: 5 parts (ethylene:ethyl acrylate:maleic anhydride=60%:28%:12%);

[0047] Composite reinforcing filler: 1.5 parts (glass fiber: nano-montmorillonite = 22:1, glass fiber aspect ratio 58:1, montmorillonite interlayer spacing 4.8nm);

[0048] Light stabilizer: 0.6 parts;

[0049] Release agent: 0.3 parts;

[0050] Interfacial compatibilizer: 2.0 parts (SMA / PB molar ratio 4:1, AN = 105 mgKOH / g);

[0051] Key parameters of preparation process:

[0052] S1 drying temperature: 90℃, vacuum drying for 10 hours; composite filler drying: 130℃ / 5 hours;

[0053] S2 silane treatment concentration 4.5wt%, treatment time 38 minutes; ultrasonic frequency 40kHz / power 600W, blending for 18 minutes;

[0054] The reaction temperature of S3 compatibilizer is 230℃, the AIBN addition amount is 0.08%, and the reaction time is 2.5 hours;

[0055] The melt blending temperature of S4 was 250°C and the screw speed was 300 rpm.

[0056] Example 2

[0057] Component ratio (parts by mass):

[0058] Polyhexamethylene adipamide matrix resin: 36 parts (Mw = 3.8 × 10 4 g / mol, amide group content 87 mol%);

[0059] Polycaprolactam matrix resin: 11 parts (terminal carboxyl content 48 mmol / kg, intrinsic viscosity 3.0 dL / g);

[0060] ABS: 38 copies;

[0061] E-EA-MAH terpolymer: 3.5 parts (ethylene:ethyl acrylate:maleic anhydride = 64%:25%:11%);

[0062] Composite reinforcing filler: 2.0 parts (glass fiber: nano-montmorillonite = 18:1, glass fiber aspect ratio 50:1, montmorillonite interlayer spacing 5.1nm);

[0063] Light stabilizer: 0.8 parts;

[0064] Release agent: 0.4 parts;

[0065] Interfacial compatibilizer: 2.5 parts (SMA / PB molar ratio 5:1, AN=112 mgKOH / g).

[0066] Key parameters of preparation process:

[0067] S1 drying temperature: 85℃, vacuum drying for 12 hours; composite filler drying: 125℃ / 5.5 hours;

[0068] S2 silane treatment concentration 5.0wt%, treatment time 45 minutes; ultrasonic frequency 40kHz / power 650W, blending for 15 minutes;

[0069] The reaction temperature of S3 compatibilizer is 235℃, the AIBN addition amount is 0.1%, and the reaction time is 3 hours;

[0070] The melt blending temperature of S4 was 245°C and the screw speed was 320 rpm.

[0071] Example 3

[0072] Component ratio (parts by mass):

[0073] Polyhexamethylene adipamide matrix resin: 48 parts (Mw = 4.5 × 10 4 g / mol, amide group content 91 mol%);

[0074] Polycaprolactam matrix resin: 5 parts (terminal carboxyl content 35 mmol / kg, intrinsic viscosity 2.4 dL / g);

[0075] ABS: 25 copies;

[0076] E-EA-MAH terpolymer: 6 parts (ethylene:ethyl acrylate:maleic anhydride=58%:30%:12%);

[0077] Composite reinforcing filler: 0.8 parts (glass fiber: nano-montmorillonite = 25:1, glass fiber aspect ratio 65:1, montmorillonite interlayer spacing 4.4nm);

[0078] Light stabilizer: 0.3 parts;

[0079] Release agent: 0.1 part;

[0080] Interfacial compatibilizer: 1.2 parts (SMA / PB molar ratio 3:1, AN = 98 mgKOH / g);

[0081] Key parameters of preparation process:

[0082] S1 drying temperature is 95℃, vacuum drying for 8 hours; composite filler drying is 135℃ / 4 hours;

[0083] S2 silane treatment concentration 3.8wt%, treatment time 30 minutes; ultrasonic frequency 42kHz / power 580W, blending for 20 minutes;

[0084] The reaction temperature of S3 compatibilizer is 220℃, the AIBN addition amount is 0.05%, and the reaction time is 2 hours;

[0085] The melt blending temperature of S4 was 255°C and the screw speed was 280 rpm.

[0086] The performance index data of the compositions prepared by the specific formulas of the three groups of embodiments of the present invention are as follows:

[0087] Performance indicators Example 1 Example 2 Example 3 Existing PA-ABS Shrinkage (%) 0.52 0.60 0.48 1.15 Tensile strength (MPa) 78.4 83.2 72.5 54.6 <![CDATA[Izod impact strength (kJ / m 2 )]]> 45.3 38.7 52.1 26.8 Heat deformation temperature (℃, 1.8MPa) 123 117 130 98 Yellowing index ΔYI after UV aging 4.2 5.8 3.6 12.3 Impact strength retention rate (%) 89.5 82.3 93.1 61.4 Shrinkage (%) 0.52 0.60 0.48 1.15 Tensile strength (MPa) 78.4 83.2 72.5 54.6

[0088] Based on the table above:

[0089] Example 1:

[0090] The molar ratio of PA66 to PA6 in the matrix resin is optimized (1:0.19), the interfacial compatibilizer block length is moderate, and the gradient interface layer thickness is 12 nm (measured by AFM).

[0091] The reduced shrinkage is attributed to the high entanglement density matrix and periodic layered structure that inhibit the molecular chain disorientation.

[0092] Example 2:

[0093] The composite filler ratio was reduced (18:1), but the exfoliation degree of montmorillonite was improved (interlayer spacing 5.1 nm), and the tensile strength was increased by 18.2% compared to Example 1 through the intercalation effect.

[0094] Higher ABS content leads to lower impact strength, but the increase of epoxy grafting points (7.2 E-EA-MAH grafting points / chain) delays photooxidation.

[0095] Example 3:

[0096] The high PA66 content (48 parts) and the glass fiber with an aspect ratio of 65:1 are synergistically reinforced, the heat deformation temperature reaches 130°C, and the heat resistance is significantly better than the control group.

[0097] The compatibilizer addition amount is low (1.2 parts) but the PB chain segments are flexible and the impact strength retention rate is 93.1%, which proves the effectiveness of the interfacial cross-linking points.

[0098] The yellowing index of the composites prepared by the three groups was ΔYI<6.0, which was more than 2 times better than that of ordinary materials.

[0099] The mechanism of anchoring butadiene phase with [2,2,6,6-tetramethyl-4-piperidinyl] sebacate is obvious.

[0100] The key to shrinkage control: The Si-OC bond network of the composite filler and the gradient interface layer jointly regulate the cooling stress distribution.

[0101] In addition, the relationship between the material shrinkage ε and the control factor is as follows:

[0102]

[0103] φf: composite filler volume fraction (converted to mass fraction in the example); E c : Interfacial energy enhancement coefficient caused by compatibilizer (positively correlated with the SMA / PB molar ratio); ΔH: Molecular chain entanglement enthalpy change (related to the PA66 / PA6 molar ratio and end group content); T: Molding cooling temperature (150-180℃ range).

[0104] In summary, the present invention significantly enhances the compatibility of the PA and ABS phases by compounding poly(hexamethylene adipamide) and poly(caprolactam) and controlling their molecular weight to form a high-entanglement-density mixed matrix network. Combined with the interfacial bridging effect of a styrene-maleic anhydride block copolymer compatibilizer, this significantly enhances the compatibility of the PA and ABS phases. During injection molding, the material exhibits increased molecular chain relaxation, reduced anisotropic shrinkage during cooling, and lowered product shrinkage.

[0105] Bis[2,2,6,6-tetramethyl-4-piperidinyl] sebacate is preferentially anchored in the butadiene phase of ABS through intermolecular hydrogen bonds with a binding energy of -18.6 to -23.4 kJ / mol, forming evenly distributed stable units. After UV-accelerated aging testing, the material's yellowing index decreases. At the same time, the glycidyl groups in the terpolymer E-EA-MAH react with the terminal amino groups of PA to generate crosslinking points that inhibit photooxidative breakage of the molecular chain and improve impact strength retention.

[0106] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A low shrinkage PA-ABS alloy material, characterized in that: The composition is composed of the following components in parts by mass: 35-48 parts of polyhexamethylene adipamide matrix resin, 5-12 parts of polycaprolactam matrix resin; 25-38 parts of acrylonitrile-butadiene-styrene copolymer; 3-6 parts of ethylene-ethyl acrylate-maleic anhydride (E-EA-MAH) terpolymer; 0.8-2.2 parts of composite reinforcing filler; 0.3-0.9 parts of light stabilizer bis[2,2,6,6-tetramethyl-4-piperidinyl]sebacate; 0.1-0.5 parts of ethylene bisstearamide as a release agent; and 1.2-2.8 parts of an interfacial compatibilizer.

2. The low shrinkage PA-ABS alloy material according to claim 1, characterized in that: The composite reinforcing filler is formed by compounding glass fiber surface-treated with γ-aminopropyltrimethoxysilane and organically modified nano-montmorillonite in a mass ratio of (18-25):

1. Its molecular structure contains chemically bonded Si-OC segments. The average diameter of the glass fiber is 9.6-12.8 μm, and the aspect ratio is controlled between 45:1 and 68:

1. The interlayer spacing of the organically modified nano-montmorillonite is 4.3-5.2 nm as determined by X-ray diffraction, and the surface of its crystal particles is grafted with an organic long-chain alkyl with the chemical formula CH2CHCOO(CH2)17CH3.

3. The low shrinkage PA-ABS alloy material according to claim 1, characterized in that: The weight average molecular weight of the polyhexamethylene adipamide matrix resin is 3.5×10 4 -4.8×10 4 g / mol, the amide group content in its molecular chain is 86-92 mol%, and the molar ratio with the polycaprolactam matrix resin is strictly maintained at 1:(0.12-0.25); the terminal carboxyl group content of the polycaprolactam matrix resin is in the range of 34-52 mmol / kg, and the intrinsic viscosity thereof measured at 25°C is 2.3-3.1 dL / g.

4. The low shrinkage PA-ABS alloy material according to claim 1, characterized in that: The molar percentages of the three monomers in the ethylene-ethyl acrylate-maleic anhydride terpolymer are ethylene:ethyl acrylate:maleic anhydride 55-68%:25-32%:7-13%. The main chain structure contains repeating units of -CH2-CH2-, -CH2-CH(OCOCH2CH3)- and -CH2-CH(COOH)- generated by free radical polymerization, and each molecular chain contains an average of 5-8 epoxypropylene grafting points.

5. The low shrinkage PA-ABS alloy material according to claim 1, characterized in that: The interfacial compatibilizer is a block copolymer formed by reacting styrene-maleic anhydride copolymer with double-terminated carboxyl polybutadiene in a molar ratio of 3:1-5:1, and its molecular structure is: -[St-alt-MAn]-b-[(HOOC(CH2)3COO)0.5-PB-(OOC(CH2)3COOH)0.5]-; Wherein, St represents a styrene monomer unit, MAn represents a maleic anhydride monomer unit, and PB represents a polybutadiene segment; the pH value (AN) of the compatibilizer is between 95-115 mgKOH / g.

6. The low shrinkage PA-ABS alloy material according to claim 1, characterized in that: A gradient interface layer is formed between the release agent ethylene bisstearamide and the composite reinforcing filler. The thickness of the gradient interface layer is 8-15 nm as measured by atomic force microscopy. The gradient interface layer comprises a periodic layered structure assembled by intermolecular forces, and its constituent units conform to the following general formula: [(CH2)2{NHC(O)(CH2)16CH3}2]·(SiO3^(2-))n·[Al(OH)4]-; In the formula, SiO3^2- comes from the deprotonation of the surface silanol groups of the composite reinforcing filler, and Al(OH)4 comes from the lamellar cations of the organically modified nano-montmorillonite.

7. A method for preparing a low shrinkage PA-ABS alloy material, characterized in that: The method is used to prepare the low shrinkage PA-ABS alloy material according to any one of claims 1 to 6, comprising the following steps: S1, drying pretreatment; S2. Surface treatment and compounding of reinforcing fillers; S3, synthesis of interfacial compatibilizer; S4, melt blending processing; S5, molding and post-processing.

8. The method for preparing a low shrinkage PA-ABS alloy material according to claim 7, characterized in that: Step S1 specifically comprises placing the polyhexamethylene adipamide matrix resin, the polycaprolactam matrix resin, and the acrylonitrile-butadiene-styrene copolymer in a vacuum oven and controlling the temperature within the range of 85-95° C. for vacuum drying for 8-12 hours to reduce the moisture content to less than 0.03%; simultaneously, drying the composite reinforcing filler at 120-135° C. for 4-6 hours to prevent residual water molecules on the interface during subsequent processing; after drying, all raw materials are transferred to a mixing bin under a nitrogen atmosphere; Step S2 is specifically as follows: The glass fiber is treated with a hydrolyzed solution of γ-aminopropyltrimethoxysilane having a concentration of 3.5-5.2 wt% for 30-45 minutes at a temperature of 55-65°C, and then centrifuged and dried. The organically modified nano-montmorillonite and the treated glass fiber are placed in an ultrasonic disperser at a mass ratio of (18-25):1 and blended for 15-20 minutes at a frequency of 40 kHz and a power of 600 W to form a composite reinforcing filler with Si-OC chemical bonds.

9. The method for preparing a low shrinkage PA-ABS alloy material according to claim 7, characterized in that: Step S3 is specifically as follows: styrene-maleic anhydride copolymer (number average molecular weight 8000-12000 g / mol) and double-end carboxyl polybutadiene (carboxyl content 3.6-4.2 mmol / g) are added to the reactor in a molar ratio of 3:1-5:1, melt blended at 220-240 ° C under nitrogen protection, and 0.05-0.1% by mass of azobisisobutyronitrile (AIBN) is added as an initiator, and the reaction is carried out for 2-3 hours to obtain a block copolymer interfacial compatibilizer.

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