Flame-retardant modified PC-ABS plastic and preparation method thereof

Abstract

The invention relates to the technical field of plastics, and discloses a flame-retardant modified PC-ABS plastic and a preparation method thereof.The flame-retardant modified PC-ABS plastic is prepared from PC resin, ABS resin, a sulfydryl flame retardant, an initiator and an antioxidant according to the mass ratio of (65-85): (15-35): (5-12): (0.15-0.4): (0.1-0.2). The sulfydryl flame retardant contains DOPO and a triazine ring structure and can play roles in condensed phase flame retardance and gas phase flame retardance, the limit oxygen index is reduced, and the flame retardance is improved. According to the present invention, the sulfydryl group of the sulfydryl flame retardant containing a large amount of the ester groups forms the sulfur free radical under the action of the dicumyl peroxide, and the sulfur free radical and the alkenyl group of the ABS are subjected to the addition cross-linking reaction so as to provide the good interfacial compatibility between the ABS and the PC polycarbonate, such that the mechanical property of the PC-ABS plastic is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of plastics, in particular to a flame-retardant modified PC-ABS plastic and a preparation method thereof. Background Art

[0002] Polycarbonate (PC) has certain flame retardancy, high transparency, and good mechanical strength, making it suitable for use as an engineering plastic in electronics, the automotive industry, and construction materials. Acrylonitrile-butadiene-styrene (ABS) copolymer offers excellent elasticity and toughness, low cost, and high temperature resistance. Combining it with polycarbonate and other materials creates plastic alloys that combine the advantages of PC and ABS, offering improved performance and a wider range of applications. However, the poor flame retardancy of PC / ASB plastics limits their practical application in fire protection and other fields.

[0003] Flame retardants are commonly added to improve the flame retardancy of plastics. Nitrogen-phosphorus flame retardants, with diverse preparation methods, strong char-forming abilities, and excellent flame retardancy, are crucial for applications in polymers such as plastics and fibers. However, poor compatibility of common flame retardants with PC and ASB can affect the mechanical properties of the plastics. This invention aims to utilize flame retardants to improve the flame retardancy of PC-ABS plastics while maintaining excellent mechanical strength. Summary of the Invention

[0004] The invention solves the problems that PC-ABS plastic has poor flame retardancy and that adding flame retardants reduces the mechanical properties of the plastic.

[0005] The technical solution of the present invention is a flame-retardant modified PC-ABS plastic and a preparation method thereof. The PC-ABS plastic comprises PC resin, ABS resin, a mercapto flame retardant, an initiator, and an antioxidant in a mass ratio of (65-85): (15-35): (5-12): (0.15-0.4): (0.1-0.2).

[0006] The preparation method of PC-ABS plastic is:

[0007] (1) Add cysteine-based DOPO-HQ and 2,4,6-tris(4-formaldehydephenyl)-1,3,5-triazine (CAS registration number 443922-06-3) to dimethyl sulfoxide, stir the reaction, cool, filter, wash with ethanol and dichloromethane in sequence, and dry to obtain a mercapto flame retardant. The preparation reaction formula is:

[0008] .

[0009] (2) PC resin, ABS resin, mercapto flame retardant, initiator, and antioxidant are mixed, extruded in a twin-screw extruder, pelletized, and then injection molded in an injection molding machine to obtain flame-retardant modified PC-ABS plastic.

[0010] Furthermore, the molar ratio of cysteine-based DOPO-HQ and 2,4,6-tris(4-formylphenyl)-1,3,5-triazine in (1) is (1.4-1.6):1.

[0011] Furthermore, the reaction in (1) is carried out in a nitrogen atmosphere, the reaction temperature is 140-160°C, and the reaction time is 24-36h.

[0012] Furthermore, the initiator in (2) is a peroxide, including dicumyl peroxide.

[0013] Furthermore, the antioxidant in (2) is a hindered phenol antioxidant, including antioxidant 1010.

[0014] Furthermore, the temperature of each section of the twin-screw extruder in (2) is 170-260°C, and the screw speed is 150-250 r / min.

[0015] Furthermore, the temperature of each section of the injection molding machine in (2) is 180-265°C, and the pressure is 50-60 MPa.

[0016] Furthermore, a method for preparing cysteine-based DOPO-HQ includes adding 10-(2,5-dihydroxyphenyl)-10-hydro-9-oxa-10-phosphaphenanthrene-10-oxide (CAS Registration No. 99208-50-1), cysteine ​​(CAS Registration No. 3374-22-9), and p-toluenesulfonic acid in a molar ratio of 1:(2.4-3.2):(0.3-0.4) to toluene, heating to 90-100°C, reflux under condensation for 12-18 hours, removing toluene by rotary evaporation, and separating the product by column chromatography and eluting with a solution of ethyl acetate and petroleum ether to obtain cysteine-based DOPO-HQ. The preparation reaction formula is:

[0017] .

[0018] The present invention provides the following beneficial technical effects: a thiol flame retardant is obtained by polymerizing cysteine-based DOPO-HQ and 2,4,6-tris(4-formylphenyl)-1,3,5-triazine. This is then blended with PC polycarbonate, ABS resin, dicumyl peroxide, and the like to form granules, and then injection molded to produce a flame-retardant modified PC-ABS plastic. The thiol flame retardant contains DOPO and triazine ring structures, forming a nitrogen-phosphorus flame retardant that acts as a condensed-phase flame retardant and a vapor-phase flame retardant. It forms an expanded carbon layer on the plastic surface, isolating oxygen and preventing heat transfer, thereby reducing the limiting oxygen index and improving flame retardancy.

[0019] The mercapto flame retardant of the present invention is a hyperbranched macromolecular polymer containing a large number of mercapto groups in the molecular chain. Under the action of dicumyl peroxide, the mercapto groups form thiol free radicals, which undergo addition cross-linking reactions with the alkenyl groups of ABS, thereby chemically bonding the flame retardant to the ABS, increasing the cross-linking degree between the ABS molecular chains, and facilitating the improvement of the mechanical properties of the ABS and its plastics.

[0020] The mercapto flame retardant of the present invention contains a large number of ester groups in the molecular main chain and has good compatibility with PC polycarbonate, so that the ABS bonded with the flame retardant and the PC polycarbonate have better interface compatibility, further improving the mechanical properties of PC-ABS plastics and having higher tensile strength and flexural strength. DETAILED DESCRIPTION

[0021] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0022] The following polycarbonate resin K-1300Y is from Dongguan Heshengyuan New Material Technology Co., Ltd. The ABS resin Toray CF25L is from Dongguan Kaiyuan Plastic Materials Co., Ltd.

[0023] Example 1

[0024] (1) To 200 mL of toluene, 50 mmol of 10-(2,5-dihydroxyphenyl)-10-hydrogen-9-oxa-10-phosphaphenanthrene-10-oxide, 160 mmol of cysteine, and 15 mmol of p-toluenesulfonic acid were added. The mixture was heated to 90 °C and refluxed under condensation for 18 h. The toluene was removed by rotary evaporation. The product was separated by column chromatography and eluted with a solution of ethyl acetate and petroleum ether to obtain cysteine-based DOPO-HQ.

[0025] (2) Add 75 mmol of cysteine-based DOPO-HQ and 50 mmol of 2,4,6-tris(4-formylphenyl)-1,3,5-triazine to 600 mL of dimethyl sulfoxide, heat to 140 °C in a nitrogen atmosphere, stir and react for 36 h, cool, filter, wash the filter cake with ethanol and dichloromethane in sequence, and dry to obtain a mercapto flame retardant.

[0026] (3) 850 g of PC resin, 150 g of ABS resin, 50 g of mercapto flame retardant, 1.5 g of diisopropylbenzene peroxide, and 1.4 g of antioxidant 1010 were mixed and extruded in a twin-screw extruder at temperatures of 170°C, 215°C, 230°C, 250°C, 260°C, and 260°C, with a screw speed of 250 r / min. The mixture was pelletized and then injection molded in an injection molding machine at temperatures of 180°C, 240°C, 260°C, and 265°C, with a pressure of 60 MPa, to obtain flame-retardant modified PC-ABS plastic.

[0027] Example 2

[0028] (1) To 150 mL of toluene, 50 mmol of 10-(2,5-dihydroxyphenyl)-10-hydrogen-9-oxa-10-phosphaphenanthrene-10-oxide, 120 mmol of cysteine, and 20 mmol of p-toluenesulfonic acid were added. The mixture was heated to 100 °C and refluxed for 12 h. The toluene was removed by rotary evaporation. The product was separated by column chromatography and eluted with a solution of ethyl acetate and petroleum ether to obtain cysteine-based DOPO-HQ.

[0029] (2) Add 70 mmol of cysteine-based DOPO-HQ and 50 mmol of 2,4,6-tris(4-formylphenyl)-1,3,5-triazine to 600 mL of dimethyl sulfoxide, heat to 160°C in a nitrogen atmosphere, stir and react for 24 h, cool, filter, wash the filter cake with ethanol and dichloromethane in sequence, and dry to obtain a mercapto flame retardant.

[0030] (3) 800 g of PC resin, 200 g of ABS resin, 70 g of mercapto flame retardant, 2.2 g of diisopropylbenzene peroxide, and 1 g of antioxidant 1010 were mixed and extruded in a twin-screw extruder at temperatures of 170°C, 215°C, 230°C, 250°C, 260°C, and 260°C, with a screw speed of 250 r / min. The mixture was pelletized and then injection molded in an injection molding machine at temperatures of 180°C, 240°C, 260°C, and 265°C, with a pressure of 60 MPa, to obtain flame-retardant modified PC-ABS plastic.

[0031] Example 3

[0032] (1) To 800 mL of dimethyl sulfoxide were added 80 mmol of cysteine-based DOPO-HQ (prepared in Example 1) and 50 mmol of 2,4,6-tris(4-formaldehydephenyl)-1,3,5-triazine. The mixture was heated to 150°C in a nitrogen atmosphere and stirred for 24 h. The mixture was cooled and filtered. The filter cake was washed with ethanol and dichloromethane in sequence and dried to obtain a mercapto flame retardant.

[0033] (2) 700 g of PC resin, 300 g of ABS resin, 100 g of mercapto flame retardant, 3.2 g of diisopropylbenzene peroxide, and 2 g of antioxidant 1010 were mixed and extruded in a twin-screw extruder at temperatures of 170°C, 215°C, 230°C, 250°C, 260°C, and 260°C, with a screw speed of 150 r / min. The mixture was pelletized and then injection molded in an injection molding machine at temperatures of 180°C, 240°C, 260°C, and 265°C, with a pressure of 50 MPa, to obtain flame-retardant modified PC-ABS plastic.

[0034] Example 4

[0035] (1) 650 g of PC resin, 350 g of ABS resin, 120 g of mercapto flame retardant (prepared in Example 1), 4 g of diisopropylbenzene peroxide, and 2 g of antioxidant 1010 were mixed and extruded in a twin-screw extruder at temperatures of 170°C, 215°C, 230°C, 250°C, 260°C, and 260°C, with a screw speed of 250 r / min. The mixture was pelletized and then injection molded in an injection molding machine at temperatures of 180°C, 240°C, 260°C, and 265°C, with a pressure of 50 MPa, to obtain flame-retardant modified PC-ABS plastic.

[0036] Comparative Example 1

[0037] (1) 850 g of PC resin, 150 g of ABS resin, 1.5 g of diisopropylbenzene peroxide, and 1.4 g of antioxidant 1010 were mixed and extruded in a twin-screw extruder at temperatures of 170°C, 215°C, 230°C, 250°C, 260°C, and 260°C, with a screw speed of 250 r / min. The mixture was pelletized and then injection molded in an injection molding machine at temperatures of 180°C, 240°C, 260°C, and 265°C, with a pressure of 60 MPa, to obtain PC-ABS plastic.

[0038] Comparative Example 2

[0039] (1) 850 g of PC resin, 150 g of ABS resin, 50 g of cysteine-based DOPO-HQ (prepared in Example 1), 1.5 g of diisopropylbenzene peroxide, and 1.4 g of antioxidant 1010 were mixed and extruded in a twin-screw extruder at temperatures of 170°C, 215°C, 230°C, 250°C, 260°C, and 260°C, with a screw speed of 250 r / min. The mixture was pelletized and then injection molded in an injection molding machine at temperatures of 180°C, 240°C, 260°C, and 265°C, with a pressure of 60 MPa, to obtain flame-retardant modified PC-ABS plastic.

[0040] Comparative Example 3

[0041] (1) The intermediate product C1 was prepared according to the method of the graduate thesis of Tianjin University of Technology, "Preparation of DOPO derivative flame retardants and research on flame retardant properties of polylactic acid composite materials". 32g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and 5.35g of 4,4'-diaminobenzophenone were mixed, heated to 190℃, stirred for 3h, cooled to 100℃, added with 150mL of toluene, filtered and washed with toluene, and then recrystallized in tetrahydrofuran to obtain the intermediate product C1 with the structural formula: .

[0042] (2) Add 75 mmol of intermediate product C1 and 50 mmol of 2,4,6-tris(4-formylphenyl)-1,3,5-triazine to 600 mL of dimethyl sulfoxide. Heat to 140 °C in a nitrogen atmosphere and stir to react for 36 h. Cool and filter. Wash the filter cake with ethanol and dichloromethane in sequence and dry to obtain a flame retardant.

[0043] (3) 850 g of PC resin, 150 g of ABS resin, 50 g of flame retardant, 1.5 g of diisopropylbenzene peroxide, and 1.4 g of antioxidant 1010 were mixed and extruded in a twin-screw extruder at temperatures of 170°C, 215°C, 230°C, 250°C, 260°C, and 260°C, with a screw speed of 250 r / min. The mixture was pelletized and then injection molded in an injection molding machine at temperatures of 180°C, 240°C, 260°C, and 265°C, with a pressure of 60 MPa, to obtain flame-retardant modified PC-ABS plastic.

[0044] The flame retardant properties of PC-ABS plastic are tested according to the method specified in GB / T 2406.1-2008.

[0045] The tensile strength is tested according to the method specified in GB / T 1040.1-2018. The flexural strength is tested according to the method specified in GB / T 9341-2008.

[0046] Table 1: Performance test of PC-ABS plastic

[0047]

[0048] The PC-ABS plastic of Comparative Example 1 does not contain a flame retardant, has a low limiting oxygen index, and has poor flame retardancy. The PC-ABS plastics of Examples 1-4 contain a mercapto flame retardant, which contains DOPO and a triazine ring structure to form a nitrogen-phosphorus flame retardant. This can play a role in condensed phase flame retardancy and gas phase flame retardancy, forming an expanded carbon layer on the plastic surface, which can isolate oxygen and prevent heat transfer, achieving a good flame retardant effect and reducing the limiting oxygen index. The mercapto flame retardant is a hyperbranched macromolecular polymer with a large number of mercapto groups in the molecular chain. Under the action of dicumyl peroxide, the mercapto groups form sulfhydryl radicals, which undergo addition cross-linking reactions with the alkenyl groups of ABS, thereby chemically bonding the flame retardant to the ABS, increasing the cross-linking degree between the ABS molecular chains, and facilitating the improvement of the mechanical properties of the ABS and its plastic. The flame retardant contains a large number of ester groups in the molecular backbone, and has good compatibility with PC polycarbonate, resulting in better interfacial compatibility between the ABS bonded with the hyperbranched flame retardant and PC polycarbonate, further improving the mechanical properties of the PC-ABS plastic, and having higher tensile strength and flexural strength.

[0049] The cysteine-based DOPO-HQ in Comparative Example 2 lacks a triazine ring structure and fails to form a nitrogen-phosphorus flame retardant system, resulting in a low limiting oxygen index and poor flame retardancy for the plastic. Furthermore, cysteine-based DOPO-HQ contains thiol groups. While it can react with the alkenyl groups of ABS, it is a small molecule, containing only two thiol groups and exhibiting significant steric hindrance. This cross-linking with ABS hinders the mechanical strength of the ABS and its plastics. Furthermore, as a small molecule with a low ester content, cysteine-based DOPO-HQ chemically bonds with ABS, effectively improving the compatibility between ABS and PC polycarbonate, resulting in low tensile and flexural strengths.

[0050] In Comparative Example 3, the intermediate product C1, which does not contain a thiol group and an ester group, is subjected to a Schiff base polymerization reaction with 2,4,6-tris(4-formaldehydephenyl)-1,3,5-triazine. The resulting flame retardant does not contain a large number of thiol groups and ester groups, cannot react with ABS, and does not improve the compatibility between ABS and PC polycarbonate, resulting in low tensile strength and flexural strength of the plastic.

[0051] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A flame retardant modified PC-ABS plastic, characterized in that: The flame retardant modified PC-ABS plastic comprises PC resin, ABS resin, mercapto flame retardant, initiator and antioxidant in a mass ratio of (65-85): (15-35): (5-12): (0.15-0.4): (0.1-0.2); The preparation method of the mercapto flame retardant comprises the following steps: adding cysteine-based DOPO-HQ and 2,4,6-tris(4-formaldehyde phenyl)-1,3,5-triazine to dimethyl sulfoxide, stirring for reaction, cooling, filtering, washing the product, and drying to obtain the mercapto flame retardant. The structural formula of the cysteine-based DOPO-HQ is .

2. The flame retardant modified PC-ABS plastic according to claim 1, characterized in that: The molar ratio of the cysteine-based DOPO-HQ to 2,4,6-tris(4-formylphenyl)-1,3,5-triazine is (1.4-1.6):

1.

3. The flame retardant modified PC-ABS plastic according to claim 1, characterized in that: The reaction is carried out in a nitrogen atmosphere at a temperature of 140-160° C. for 24-36 hours.

4. The flame retardant modified PC-ABS plastic according to claim 1, characterized in that: The initiator is a peroxide, including dicumyl peroxide; the antioxidant is a hindered phenol antioxidant, including antioxidant 1010.

5. The flame retardant modified PC-ABS plastic according to claim 1, characterized in that: The preparation method of the cysteine-based DOPO-HQ comprises: adding a structural formula of 10-(2,5-dihydroxyphenyl)-10-hydrogen-9-oxa-10-phosphaphenanthrene-10-oxide, cysteine, and p-toluenesulfonic acid are heated to 90-100° C., condensed and refluxed for 12-18 hours, toluene is removed by rotary evaporation, and the product is separated by column chromatography to obtain cysteine-based DOPO-HQ.

6. The flame retardant modified PC-ABS plastic according to claim 5, characterized in that: The molar ratio of the 10-(2,5-dihydroxyphenyl)-10-hydrogen-9-oxa-10-phosphaphenanthrene-10-oxide, cysteine ​​and p-toluenesulfonic acid is 1:(2.4-3.2):(0.3-0.4).

7. A method for preparing the flame retardant modified PC-ABS plastic according to any one of claims 1 to 6, characterized in that: The preparation method comprises: mixing PC resin, ABS resin, mercapto flame retardant, initiator and antioxidant, extruding in a twin-screw extruder, pelletizing, and then injection molding in an injection molding machine to obtain flame-retardant modified PC-ABS plastic.

8. The method for preparing the flame retardant modified PC-ABS plastic according to claim 7, characterized in that: The temperature of each section of the twin-screw extruder is 170-260° C., and the screw speed is 150-250 r / min.

9. The method for preparing the flame retardant modified PC-ABS plastic according to claim 7, characterized in that: The temperature of each section of the injection molding machine is 180-265° C., and the pressure is 50-60 MPa.

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