High-toughness modified pc / abs plastic alloy and preparation method thereof

Abstract

The application relates to the technical field of high polymer materials, and discloses a high-toughness modified PC / ABS plastic alloy and a preparation method thereof, wherein the plastic alloy comprises the following raw materials in parts by weight: 100 parts by weight of PC, 30-40 parts by weight of ABS, 0.2-0.5 parts by weight of an antioxidant, 6-10 parts by weight of a compatible agent, 2-5 parts by weight of a phosphorus-containing modified melamine flame retardant and 1-3 parts by weight of salicylaldehyde modified melamine; the phosphorus-containing modified melamine flame retardant is used to improve the flame retardant property of the plastic alloy; the salicylaldehyde modified melamine is used to improve the antibacterial property of the plastic alloy; the hydroxyl structures contained in the two substances and the maleic anhydride structures contained in the base material are used to react to form a three-dimensional network structure, so that the mechanical property of the plastic alloy is synergistically improved.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a high-toughness modified PC / ABS plastic alloy and its preparation method. Background Technology

[0002] Polycarbonate (PC) is a thermoplastic engineering plastic with excellent overall performance, possessing high tensile strength and excellent optical properties, but it is prone to stress cracking and has poor processability. Acrylonitrile-butadiene-styrene copolymer (ABS) is a thermoplastic engineering plastic with good processability and impact resistance, but its toughness is poor. PC / ABS plastic alloys, made from PC and ABS, are high-performance polymer composite materials that combine the high strength, high heat resistance, and excellent impact toughness of PC with the good processing flowability, chemical resistance, and cost advantages of ABS. They are widely used in automotive interior and exterior parts, electronic and electrical housings, home appliances, office equipment, and consumer electronics. However, with the rapid development of modern industry, higher and more comprehensive requirements are being placed on the performance of PC / ABS plastic alloys.

[0003] For example, the patent application with publication number CN 120424485 A discloses a high-toughness halogen-free flame-retardant PC / ABS alloy and its preparation method. The invention uses PC, ABS, antioxidants, halogen-free flame retardants and other raw materials to prepare an alloy with excellent flame retardant and impact resistance properties, but does not improve the antibacterial properties of the alloy. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this invention provides a high-toughness modified PC / ABS plastic alloy and its preparation method. The prepared PC / ABS plastic alloy exhibits excellent toughness, flame retardancy, and long-lasting antibacterial properties.

[0006] (II) Technical Solution

[0007] A high-toughness modified PC / ABS plastic alloy, the plastic alloy comprising the following raw materials in parts by weight: 100 parts by weight of PC, 30-40 parts by weight of ABS, 0.2-0.5 parts by weight of antioxidant, 6-10 parts by weight of compatibilizer, 2-5 parts by weight of phosphorus-containing modified melamine flame retardant, and 1-3 parts by weight of salicylaldehyde-modified melamine;

[0008] The preparation method of the high-toughness modified PC / ABS plastic alloy includes the following steps:

[0009] Dry ABS and dry PC are added to a high-speed mixer and mixed evenly. Antioxidant, compatibilizer, phosphorus-modified melamine flame retardant and salicylaldehyde-modified melamine are added and the mixture is continued to mix for 20-30 minutes. Then, it is placed in a twin-screw extruder for melt mixing and even mixing. Granulation is carried out in a granulator and injection molding is carried out in an injection molding machine to obtain a high-toughness modified PC / ABS plastic alloy.

[0010] Preferably, the compatibilizer is maleic anhydride-grafted ABS (ABS-g-MAH). In this invention, ABS-g-MAH is used as a compatibilizer. The ABS segments in the ABS-g-MAH have a similar structure to the ABS phase in the alloy, which can form physical entanglement and mutual solubility. The maleic anhydride groups in the ABS-g-MAH react with the terminal hydroxyl groups of PC to form chemical bonds, thereby significantly improving the interfacial bonding force between the PC and ABS phases. The MAH active groups can not only form stable chemical bonds with PC, but the remaining active groups (such as carboxyl groups and unreacted maleic anhydride groups) will continue to react with the hydroxyl groups contained in the phosphorus-modified melamine flame retardant and salicylaldehyde-modified melamine to form stable chemical bonds, increase chemical crosslinking sites, and form a huge three-dimensional crosslinked network structure. When the material is subjected to external impact, the crosslinked network structure can not only absorb and share the external impact force, but also disperse the impact force to other molecular chains, significantly improving the impact resistance of the alloy. The better the impact resistance of the alloy, the better its toughness.

[0011] Preferably, the antioxidant is one of antioxidant 1010 and antioxidant 168.

[0012] Preferably, the temperature of each section of the twin-screw extruder is 250℃, 280℃, 280℃, and 260℃, and the screw speed is 120-150 rpm.

[0013] Preferably, the injection molding machine has an injection temperature of 230°C and an injection pressure of 90 MPa.

[0014] Preferably, the preparation method of the salicylaldehyde-modified melamine includes the following steps:

[0015] Melamine was added to deionized water and stirred to dissolve. Salicylic aldehyde was then added, and the temperature was controlled at 80-90℃. The reaction was stirred for 70-76 hours. After the reaction was completed, the mixture was washed with deionized water and dried to obtain salicylic aldehyde-modified melamine. In this reaction, the amino group in melamine reacted with the aldehyde group in salicylic aldehyde to form a Schiff base reaction, thus introducing a phenolic hydroxyl group into the product. The synthetic route is as follows:

[0016] .

[0017] Preferably, the molar ratio of melamine to salicylaldehyde is 1:4-4.5.

[0018] Preferably, the preparation method of the phosphorus-modified melamine flame retardant includes the following steps:

[0019] Step (1): Add dried dimethyl phosphite to a flask, then add allyl glycidyl ether, mix well, and then add sodium methoxide solution. Control the temperature at 70-75℃ and react for 2-4 hours. After the reaction is complete, cool to room temperature and rotary evaporate to obtain the intermediate. In this reaction, dimethyl phosphite and allyl glycidyl ether undergo an addition reaction under alkaline conditions to obtain the intermediate. The synthetic route is as follows:

[0020] ;

[0021] Step (2): Melamine and the intermediate are added to a flask containing ethylene glycol solvent and refluxed for 6-8 hours. After the reaction is complete, the mixture is cooled to room temperature, washed with deionized water, and dried to obtain a phosphorus-modified melamine flame retardant. In this reaction, the amino groups in melamine react with the epoxy groups in the intermediate to obtain the phosphorus-modified melamine flame retardant. The reaction synthesis route is as follows:

[0022] ; During the blending process with ABS-g-MAH, the hydroxyl groups can undergo a ring-opening reaction with the maleic anhydride structure therein, confining the small molecule flame retardant into a macromolecular structure. On the one hand, this increases the compatibility between the small molecule flame retardant and the substrate and reduces the precipitation performance of the small molecule flame retardant. On the other hand, the small molecule flame retardant of this invention contains three hydroxyl groups, which can react with more maleic anhydride structures and the carboxyl groups obtained after ring opening to form more chemical bonds, thereby obtaining an interwoven three-dimensional network structure. This structure can absorb and disperse the impact force when the material is impacted, thereby improving the impact resistance of the substrate.

[0023] More preferably, in step (1), the molar ratio of dimethyl phosphite to allyl glycidyl ether is 1:1-1.2.

[0024] More preferably, in step (1), the mass fraction of the sodium methoxide solution is 30%, wherein the sodium methoxide solution is a sodium methoxide solution with methanol as the solvent.

[0025] More preferably, in step (2), the molar ratio of melamine to intermediate is 1:3-3.2.

[0026] (iii) Beneficial technical effects

[0027] The phosphorus-modified melamine flame retardant prepared by this invention has excellent flame retardant properties. The specific mechanism is as follows: the phosphate ester group in the structure decomposes upon heating to generate strong dehydrating acids such as phosphoric acid and polyphosphoric acid. These acidic substances can catalyze the dehydration and carbonization of the polymer substrate to form a dense, heat-insulating, and oxygen-barrier carbon layer. The carbon layer can prevent heat and oxygen from diffusing inward and prevent combustible gases from volatilizing outward, thereby inhibiting the combustion cycle. The melamine structure in the structure decomposes upon heating to generate non-combustible gases such as NH3, N2, and H2O. These gases can dilute the concentration of oxygen and combustible gases, reduce the combustion intensity, and play an auxiliary flame retardant role.

[0028] Conventional small-molecule antibacterial agents added to the substrate are prone to precipitation, resulting in poor long-lasting antibacterial effects. This invention introduces a hydroxyl structure into salicylaldehyde-modified melamine. The hydroxyl structure reacts with the maleic anhydride and carboxyl structures in the substrate, confining the small-molecule antibacterial agent to a macromolecular structure and improving the antibacterial durability of the small-molecule structure.

[0029] The phosphorus-modified melamine flame retardant and salicylaldehyde-modified melamine prepared by this invention contain a large number of hydroxyl groups, which can form chemical bonds with the maleic anhydride and carboxyl structures in the substrate. On the one hand, this improves the resistance of small molecule structures to precipitation in the substrate. On the other hand, the reaction generates more chemical crosslinking sites. When subjected to impact, the impact force is dispersed along the crosslinking sites to other molecular chains, significantly improving the impact resistance of the substrate. Detailed Implementation

[0030] To help understand the present invention, the following embodiments are provided for further explanation; the embodiments described below are illustrative and not limiting, and should not be used to limit the scope of protection of the present invention.

[0031] Example 1

[0032] Step (1): Add 0.1 mol of melamine to deionized water, stir to dissolve, add 0.4 mol of salicylaldehyde, control the temperature at 85℃, stir and react for 72 h. After the reaction is completed, wash with deionized water and dry to obtain salicylaldehyde modified melamine.

[0033] Step (2): Add 0.4 mol of dry dimethyl phosphite to a flask, then add 0.45 mol of allyl glycidyl ether, mix well, then add 30% sodium methoxide solution, control the temperature at 75℃, react for 2 hours, after the reaction is completed, cool to room temperature, and rotary evaporate to obtain the intermediate.

[0034] Step (3): Add 0.1 mol of melamine and 0.3 mol of intermediate to a flask containing ethylene glycol solvent, reflux for 7 h, cool to room temperature after the reaction is complete, wash with deionized water, and dry to obtain phosphorus-modified melamine flame retardant.

[0035] Step (4): Add 35 parts by weight of dried ABS and 100 parts by weight of dried PC to a high-speed mixer and mix evenly. Add 0.4 parts by weight of antioxidant 1010, 6 parts by weight of ABS-g-MAH, 2 parts by weight of phosphorus-modified melamine flame retardant, and 1 part by weight of salicylaldehyde-modified melamine and continue mixing for 30 minutes. Then place it in a twin-screw extruder to melt and mix evenly. The temperature of each section of the twin-screw extruder is 250℃, 280℃, 280℃, and 260℃, and the screw speed is 120 rpm. Granulate in a granulator and injection mold in an injection molding machine. The injection temperature is 230℃ and the injection pressure is 90 MPa to obtain a high-toughness modified PC / ABS plastic alloy.

[0036] Example 2

[0037] Step (1): Add 0.1 mol of melamine to deionized water, stir to dissolve, add 0.43 mol of salicylaldehyde, control the temperature at 80℃, stir and react for 76 h. After the reaction is completed, wash with deionized water and dry to obtain salicylaldehyde modified melamine.

[0038] Step (2): Add 0.4 mol of dry dimethyl phosphite to a flask, then add 0.4 mol of allyl glycidyl ether, mix well, then add 30% sodium methoxide solution, control the temperature at 75℃, react for 3 hours, after the reaction is completed, cool to room temperature, and rotary evaporate to obtain the intermediate.

[0039] Step (3): Add 0.1 mol of melamine and 0.32 mol of intermediate to a flask containing ethylene glycol solvent, reflux for 7 h, cool to room temperature after the reaction is complete, wash with deionized water, and dry to obtain phosphorus-modified melamine flame retardant.

[0040] Step (4): Add 30 parts by weight of dried ABS and 100 parts by weight of dried PC to a high-speed mixer and mix evenly. Add 0.2 parts by weight of antioxidant 1010, 7 parts by weight of ABS-g-MAH, 3 parts by weight of phosphorus-modified melamine flame retardant, and 2 parts by weight of salicylaldehyde-modified melamine and continue mixing for 25 minutes. Then place it in a twin-screw extruder to melt and mix evenly. The temperature of each section of the twin-screw extruder is 250℃, 280℃, 280℃, and 260℃, and the screw speed is 120 rpm. Granulate in a granulator and injection mold in an injection molding machine. The injection temperature is 230℃ and the injection pressure is 90 MPa to obtain a high-toughness modified PC / ABS plastic alloy.

[0041] Example 3

[0042] Step (1): Add 0.1 mol of melamine to deionized water, stir to dissolve, add 0.45 mol of salicylaldehyde, control the temperature at 90℃, stir and react for 70 h, wash with deionized water after the reaction is completed, dry to obtain salicylaldehyde modified melamine.

[0043] Step (2): Add 0.4 mol of dry dimethyl phosphite to a flask, then add 0.48 mol of allyl glycidyl ether, mix well, then add 30% sodium methoxide solution, control the temperature at 70℃, react for 4 h, after the reaction is completed, cool to room temperature, and rotary evaporate to obtain the intermediate.

[0044] Step (3): Add 0.1 mol of melamine and 0.32 mol of intermediate to a flask containing ethylene glycol solvent, reflux for 6 h, cool to room temperature after the reaction is complete, wash with deionized water, and dry to obtain phosphorus-modified melamine flame retardant.

[0045] Step (4): Add 40 parts by weight of dried ABS and 100 parts by weight of dried PC to a high-speed mixer and mix evenly. Add 0.5 parts by weight of antioxidant 168, 8 parts by weight of ABS-g-MAH, 4 parts by weight of phosphorus-modified melamine flame retardant, and 2.5 parts by weight of salicylaldehyde-modified melamine and continue mixing for 20 minutes. Then place it in a twin-screw extruder to melt and mix evenly. The temperature of each section of the twin-screw extruder is 250℃, 280℃, 280℃, and 260℃, and the screw speed is 120 rpm. Granulate in a granulator and injection mold in an injection molding machine. The injection temperature is 230℃ and the injection pressure is 90 MPa to obtain a high-toughness modified PC / ABS plastic alloy.

[0046] Example 4

[0047] Step (1): Add 0.1 mol of melamine to deionized water, stir to dissolve, add 0.2 mol of salicylaldehyde, control the temperature at 85℃, stir and react for 76 h, wash with deionized water after the reaction is completed, dry to obtain salicylaldehyde modified melamine.

[0048] Step (2): Add 0.4 mol of dry dimethyl phosphite to a flask, then add 0.45 mol of allyl glycidyl ether, mix well, then add 30% sodium methoxide solution, control the temperature at 75℃, react for 3 hours, after the reaction is completed, cool to room temperature, and rotary evaporate to obtain the intermediate.

[0049] Step (3): Add 0.1 mol of melamine and 0.3 mol of intermediate to a flask containing ethylene glycol solvent, reflux for 8 hours, cool to room temperature after the reaction is complete, wash with deionized water, and dry to obtain phosphorus-modified melamine flame retardant.

[0050] Step (4): Add 40 parts by weight of dried ABS and 100 parts by weight of dried PC to a high-speed mixer and mix evenly. Add 0.4 parts by weight of antioxidant 1010, 10 parts by weight of ABS-g-MAH, 5 parts by weight of phosphorus-modified melamine flame retardant, and 3 parts by weight of salicylaldehyde-modified melamine and continue mixing for 30 minutes. Then place it in a twin-screw extruder to melt and mix evenly. The temperature of each section of the twin-screw extruder is 250℃, 280℃, 280℃, and 260℃, and the screw speed is 120 rpm. Granulate in a granulator and injection mold in an injection molding machine. The injection temperature is 230℃ and the injection pressure is 90 MPa to obtain a high-toughness modified PC / ABS plastic alloy.

[0051] Comparative Example 1

[0052] The difference between this comparative example and Example 1 is that step (4) does not contain phosphorus-modified melamine flame retardant, while the remaining steps are the same as in Example 1.

[0053] Comparative Example 2

[0054] The difference between this comparative example and Example 1 is that in step (4), an intermediate is used instead of the phosphorus-modified melamine flame retardant, while the remaining steps are the same as in Example 1.

[0055] Comparative Example 3

[0056] The difference between this comparative example and Example 1 is that step (4) does not contain salicylaldehyde-modified melamine, while the other steps are the same as in Example 1.

[0057] Comparative Example 4

[0058] The difference between this comparative example and Example 1 is that in step (4), salicylaldehyde is used instead of salicylaldehyde to modify melamine, and the remaining steps are the same as in Example 1.

[0059] Impact strength shall be tested using an impact testing machine in accordance with GB / T1843-2008;

[0060] According to GB / T1040-2006, tensile properties were tested using a universal tensile testing machine at a tensile rate of 50 mm / min.

[0061] Table 1:

[0062]

[0063] As shown in Table 1, the plastic alloy prepared by this invention exhibits excellent toughness. Comparative Example 1 does not contain phosphorus-modified melamine flame retardant, and Comparative Example 3 does not contain salicylaldehyde-modified melamine. Both phosphorus-modified melamine flame retardant and salicylaldehyde-modified melamine contain hydroxyl structures, which can react with maleic anhydride structures and unreacted carboxyl structures in the substrate, increasing chemical crosslinking sites. Under impact, they can absorb and disperse impact stress, significantly improving the mechanical properties of the plastic alloy. Comparative Example 2 uses an intermediate instead of phosphorus-modified melamine flame retardant, and its mechanical properties are better than those of Comparative Examples 1 and 3, but not as good as those of the embodiments of this invention. The presumed reason is that the intermediate contains an epoxy group, which, when added, can react with the hydroxyl structures in the substrate, thereby improving the mechanical properties of the plastic alloy. However, it cannot form a chemical crosslinking network structure, therefore its mechanical properties are better than those of Comparative Examples 1 and 3, but not as good as those of the embodiments of this invention.

[0064] According to GB / T2408-2021, the UL-94 flammability rating was tested using a vertical flammability tester.

[0065] Table 2:

[0066]

[0067] As shown in Table 2, the plastic alloy prepared by this invention has excellent flame retardant properties.

[0068] According to GB21551.2-2010, the antibacterial properties were tested at 0h and 100 days, and the test strain was Escherichia coli.

[0069] Table 3:

[0070]

[0071] As shown in Table 3, the plastic alloy prepared by the present invention has excellent long-lasting antibacterial properties, with the antibacterial performance reaching up to 99.9% after 7 days. In the embodiments of the present invention, on the one hand, small molecules are chemically bound into the macromolecular structure, which reduces the precipitation performance of small molecules. On the other hand, the huge three-dimensional cross-linked network structure formed hinders the precipitation effect of small molecules, further improving the antibacterial durability. Therefore, it has long-lasting antibacterial properties. In contrast, Comparative Example 4 does not contain the above structure, so its antibacterial durability is poor.

[0072] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A high-toughness modified PC / ABS plastic alloy, characterized in that, The plastic alloy comprises the following raw materials in parts by weight: 100 parts PC, 30-40 parts ABS, 0.2-0.5 parts antioxidant, 6-10 parts compatibilizer, 2-5 parts phosphorus-modified melamine flame retardant, and 1-3 parts salicylaldehyde-modified melamine. The structural formula of the phosphorus-modified melamine flame retardant is: ； The structural formula of the salicylaldehyde-modified melamine is: ； The preparation method of the high-toughness modified PC / ABS plastic alloy includes the following steps: Dry ABS and dry PC are added to a high-speed mixer and mixed evenly. Antioxidant, compatibilizer, phosphorus-modified melamine flame retardant and salicylaldehyde-modified melamine are added and the mixture is continued to mix for 20-30 minutes. Then, it is placed in a twin-screw extruder for melt mixing and even mixing. Granulation is carried out in a granulator and injection molding is carried out in an injection molding machine to obtain a high-toughness modified PC / ABS plastic alloy.

2. The high-toughness modified PC / ABS plastic alloy according to claim 1, characterized in that, The compatibilizer is ABS-g-MAH; the antioxidant is one of antioxidant 1010 and antioxidant 168.

3. The high-toughness modified PC / ABS plastic alloy according to claim 1, characterized in that, The twin-screw extruder has temperatures of 250℃, 280℃, 280℃, and 260℃ in each section, and a screw speed of 120-150 rpm.

4. The high-toughness modified PC / ABS plastic alloy according to claim 1, characterized in that, The injection molding machine has an injection temperature of 230℃ and an injection pressure of 90MPa.

5. The high-toughness modified PC / ABS plastic alloy according to claim 1, characterized in that, The preparation method of the salicylaldehyde-modified melamine includes the following steps: Melamine was added to deionized water and stirred until dissolved. Salicylic aldehyde was then added to the solution. The temperature was controlled at 80-90℃, and the reaction was stirred for 70-76 hours. After the reaction was completed, the mixture was washed with deionized water and dried to obtain salicylaldehyde-modified melamine.

6. The high-toughness modified PC / ABS plastic alloy according to claim 5, characterized in that, The molar ratio of melamine to salicylaldehyde is 1:4-4.

5.

7. The high-toughness modified PC / ABS plastic alloy according to claim 1, characterized in that, The preparation method of the phosphorus-modified melamine flame retardant includes the following steps: Step (1): Add the dried dimethyl phosphite to the flask, then add allyl glycidyl ether, mix well, then add sodium methoxide solution, control the temperature at 70-75℃, react for 2-4 hours, after the reaction is completed, cool to room temperature, and rotary evaporate to obtain the intermediate. Step (2): Add melamine and intermediate to a flask containing ethylene glycol solvent, reflux for 6-8 hours, cool to room temperature after the reaction is complete, wash with deionized water, and dry to obtain phosphorus-modified melamine flame retardant.

8. The high-toughness modified PC / ABS plastic alloy according to claim 7, characterized in that, In step (1), the molar ratio of dimethyl phosphite and allyl glycidyl ether is 1:1-1.

2.

9. The high-toughness modified PC / ABS plastic alloy according to claim 7, characterized in that, In step (1), the mass fraction of the sodium methoxide solution is 30%.

10. The high-toughness modified PC / ABS plastic alloy according to claim 7, characterized in that, In step (2), the molar ratio of melamine to intermediate is 1:3-3.2.

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