Flame-retardant PBT / brominated polycarbonate composition as well as preparation method and application thereof

Abstract

The invention discloses a flame-retardant PBT (Polybutylece Terephthalate) / brominated polycarbonate composition, which comprises the following components in parts by weight: 40-60 parts of PBT; 30 to 50 parts of brominated polycarbonate; 0.2 to 0.5 part of an anti-dripping agent; 10 to 15 parts of a glycidyl methacrylate grafted toughening agent; the viscosity average molecular weight of the brominated PC ranges from 13000 to 30000, and the molar ratio of the bisphenol A to the tetrabromobisphenol A is (55 to 40) to (45 to 60). The brominated polycarbonate with specific parameters is selected and cooperated with the glycidyl methacrylate grafted toughening agent, so that the flame retardance of V-0 can be realized, and the advantages of high low-temperature toughness (notch impact property tested at-30 DEG C) and low shrinkage after baking can also be realized.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to a flame retardant PBT / brominated polycarbonate composition and a preparation method and application thereof. Background Art

[0002] Polybutylene terephthalate (PBT) is a crystalline thermoplastic with the advantages of fast crystallization speed, chemical resistance and good fluidity, but its main disadvantage is low toughness. Polycarbonate (PC) is a transparent and colorless thermoplastic. Its biggest advantage is high toughness and good dimensional stability, but its fluidity and solvent resistance are poor. PBT and PC alloy can overcome the shortcomings of PC such as poor chemical resistance and poor molding processability, and at the same time can make up for the disadvantage of poor toughness of PBT, and can obtain good comprehensive performance. However, PBT and PC are both polyester materials. Under high temperature and high shear processing conditions, serious ester exchange reactions will occur between the two, thus affecting the performance of the alloy.

[0003] The existing technology solves the defects of insufficient heat resistance and solvent resistance by adding brominated PC. For example, Chinese patent application CN116355367A discloses a flame retardant PBT composition. The components of the PBT composition include, by weight: 35-45 parts of PBT, 20-30 parts of brominated PC, 5-10 parts of isosorbide copolymerized PC, 2-6 parts of antimony flame retardant, 0.1-0.4 parts of ester exchange inhibitor, and 2-5 parts of talc. Among them, the glass transition temperature of brominated PC is 160-175°C. However, the notched impact performance of the flame retardant PBT composition tested at -30°C needs to be further optimized. Summary of the invention

[0004] The object of the present invention is to overcome the above technical defects and provide a flame retardant PBT / polycarbonate composition with V-0 flame retardancy, good -30°C notched impact performance and low shrinkage.

[0005] The present invention is achieved through the following technical solutions: A flame retardant PBT / brominated polycarbonate composition, comprising the following components in parts by weight: PBT 40-60 parts; 30-50 parts of brominated polycarbonate; Anti-dripping agent 0.2-0.5 parts; 10-15 parts of glycidyl methacrylate graft toughening agent; The viscosity average molecular weight of the brominated polycarbonate is in the range of 13000-30000, and the molar ratio of bisphenol A to tetrabromobisphenol A is (55-40): (45-60).

[0006] The viscosity average molecular weight range of the brominated polycarbonate can be 13000, 14000, 15000, 16000, 17000, 18000, 19000, 20000, 21000, 22000, 23000, 24000, 25000, 26000, 27000, 28000, 29000, 30000, etc., and the molar ratio of bisphenol A:tetrabromobisphenol A can be 55:45, 54:46, 53:47, 52:48, 51:49, 50:50, 49:51, 48:52, 47:53, 46:54, 45:55, etc.

[0007] Preferably, the viscosity average molecular weight of the brominated PC is in the range of 17000-24000, and the molar ratio of bisphenol A to tetrabromobisphenol A is (50-45): (50-55).

[0008] In the flame retardant PBT / brominated polycarbonate composition of the present invention, PBT accounts for no less than 35wt% of the total weight. The content of PBT can be 40 parts, 42 parts, 44 parts, 46 parts, 48 ​​parts, 50 parts, 52 parts, 54 parts, 56 parts, 58 parts, 60 parts, etc., the content of brominated polycarbonate can be 30 parts, 32 parts, 34 parts, 36 parts, 38 parts, 40 parts, 42 parts, 44 parts, 46 parts, 48 ​​parts, 50 parts, etc., the content of anti-dripping agent can be 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, etc. The content of glycidyl methacrylate grafted toughening agent can be 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, etc.

[0009] Brominated polycarbonate can be a commercial product or can be obtained by the triphosgene method, which is specifically as follows: add bisphenol A, tetrabromobisphenol A, and a solvent to a reactor equipped with an agitator, a condenser, triphosgene, and a sodium hydroxide dropping device, add a sodium hydroxide solution under stirring, and stir until the tetrabromobisphenol A is completely dissolved. Then add a 1,2-dichloroethane solution of triphosgene dropwise. After all the additions are completed, stir and react at 25-30°C for 2-3 hours. After the reaction is completed, the solution is allowed to stand, the organic phase is separated, the organic phase is repeatedly washed with deionized water, and the organic phase is added to methanol for precipitation to obtain brominated polycarbonate. The molar ratio of bisphenol A:tetrabromobisphenol A in brominated PC is controlled by controlling the amount and molar ratio of bisphenol A and tetrabromobisphenol A.

[0010] The solvent may be 1,2-dichloroethane, chloroform, etc. The solvent is only used as a medium and does not participate in the reaction. The amount of solvent has no effect on the final result, and it is sufficient to be able to completely dissolve. There is no clear regulation on the amount of solvent, but the economic efficiency needs to be considered.

[0011] The test method of viscosity average molecular weight of brominated polycarbonate is as follows: weigh 4-10 mg of sample and place it in a glass bottle, add 1 mL of hexafluoroisopropanol according to the ratio of 1 mg sample to dissolve and let it stand for about 12 hours; if the sample is not completely dissolved after standing, place it on a heating plate or steam bath to heat it to completely dissolve. Then use a syringe with an organic nylon filter to filter the sample solution and place it in a glass bottle. Then enter the gel permeation chromatograph (GPC) for testing.

[0012] The glycidyl methacrylate grafted toughening agent is selected from at least one of a glycidyl methacrylate grafted ethylene-methyl acrylate copolymer toughening agent and a glycidyl methacrylate grafted ethylene-butyl acrylate copolymer toughening agent.

[0013] In the glycidyl methacrylate grafted toughening agent, the grafting rate of glycidyl methacrylate is 0.4-2.1wt%, preferably 0.8-1.3wt%.

[0014] The glycidyl methacrylate grafted toughening agent can be obtained commercially or by self-production. The self-production method is as follows: glycidyl methacrylate, initiator, and toughening agent before grafting (ethylene-methyl acrylate copolymer toughening agent, ethylene-butyl acrylate copolymer toughening agent) are uniformly mixed, and extruded and granulated by a twin-screw extruder (screw temperature is 150-180°C, and aspect ratio is greater than or equal to 40:1) to obtain the glycidyl methacrylate grafted toughening agent. The initiator is selected from at least one of dicumyl peroxide, di-tert-butyl peroxide, tert-butyl hydroperoxide, and isopropylbenzene hydroperoxide, and the addition amount is 0.2-0.8wt% of the amount of toughening agent before grafting.

[0015] The test method for the GMA grafting rate of glycidyl methacrylate grafted toughening agents is: acid-base titration method. The specific operation method can be: put the grafted material into xylene and heat it under reflux to dissolve, after cooling, add a certain amount of 0.05mol / L potassium hydroxide-ethanol solution, and then heat it under reflux for 8h, use 0.1% phenolphthalein solution as an indicator, and titrate to the end point with 0.05mol / L HCl-isopropanol solution while it is hot. The grafting rate G is calculated using the following formula: G = (N1 × Vl - N2 × V2) × M ÷ w ÷ 10 Where: N1: KOH-ethanol solution equivalent concentration, N; V1: volume of KOH-ethanol solution, ml; N2: HCl-isopropanol solution equivalent concentration, N; V2: volume of HCl-isopropanol solution, ml; M: equivalent mass of GMA, g; w: weight of the dried sample after extraction, g.

[0016] The intrinsic viscosity of the PBT is 1.1-1.5 dl / g.

[0017] The test method for the intrinsic viscosity of PBT is as follows: the distilled phenol and o-dichlorobenzene are mixed in a mass ratio of 3:2 into a completely uniform state, 15 mL of phenol-o-xylene solution is filtered through a sand core funnel, poured into a viscometer, and placed in a water bath at 25±0.01°C. After keeping for 10 minutes, the outflow time of the phenol-o-dichlorobenzene solution is measured, and the average of 5 measured values ​​is taken as the outflow time t0 of the pure solvent.

[0018] Accurately weigh 0.1250±0.0002g of the shredded sample on an analytical balance and place it in a 25mL volumetric flask. Then add 15-20mL of a mixed solvent of phenol-o-dichlorobenzene, place it on a heating plate or steam bath to heat it to completely dissolve, take it out, cool it down, place it in a water bath at 25±0.01℃, keep the temperature constant for 10 minutes, and then add the solvent to the volumetric flask to the scale line. Filter the above solution through a sand core funnel and fill it into a viscometer, place it in a constant temperature water bath (25±0.01℃) for 10 minutes, and then measure its outflow time. Repeat the measurement three times and take the average value as the solution outflow time t1.

[0019] The calculation formula is as follows:

[0020] Where: [η] is the intrinsic viscosity, in deciliters per gram (dL / g); t0 is the solvent flow time, in seconds (s); t1 is the solution flow time, in seconds (s); c is the solution concentration, in grams per hundred milliliters (g / 100ml) By weight, it also includes 0.05-0.5 parts of ester exchange inhibitor, which is selected from one or more of sodium hydrogen phosphate, triethanolamine, trimethylstannate, disodium dihydrogen pyrophosphate, triphenyl phosphate, zinc dihydrogen phosphate and the like.

[0021] The anti-dripping agent is selected from polytetrafluoroethylene.

[0022] It is possible to choose whether to add 0-2 parts of auxiliary agents according to actual needs, and the auxiliary agents are selected from one or more of antioxidants and lubricants.

[0023] The preparation method of the flame retardant PBT / PC composition comprises the following steps: according to the proportion, the components are uniformly mixed, and the flame retardant PBT / PC composition is obtained by extruding and granulating through a twin-screw extruder. The temperature of the first zone is 200-220°C, the temperature of the second zone is 220-230°C, the temperature of the third zone is 230-240°C, the temperature of the fourth zone is 230-240°C, the temperature of the fifth zone is 230-240°C, the temperature of the sixth zone is 230-240°C, the temperature of the seventh zone is 240-250°C, the temperature of the eighth zone is 240-250°C, the temperature of the ninth zone is 230-240°C, and the main engine speed is 300-400 rpm.

[0024] The application of flame-retardant PBT / PC compositions is mainly used in the field of electronics and electrical appliances, especially in electronic and electrical products with flame retardancy and low-temperature toughness requirements, such as for the preparation of photovoltaic modules and inverter housings.

[0025] The present invention has the following beneficial effects: The present invention can reduce the ester exchange reaction with PBT resin to a certain extent by selecting brominated polycarbonate with specific parameters. At the same time, by cooperating with glycidyl methacrylate grafted toughening agents, PBT / brominated polycarbonate / glycidyl methacrylate grafted toughening agents have better compatibility, can achieve V-0 flame retardancy, can also achieve high low-temperature toughness (notched impact performance tested at -30°C), and has the advantage of anti-bake shrinkage. DETAILED DESCRIPTION

[0026] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0027] The sources of raw materials used in the present invention are as follows: PBT resin-A: brand GX121, intrinsic viscosity 1.0dl / g, from the Engineering Plastics Plant of Yizheng Branch of Sinopec Asset Management Co., Ltd.; PBT resin-B: brand GL236, intrinsic viscosity 1.3dl / g, from the Engineering Plastics Plant of Yizheng Branch of Sinopec Asset Management Co., Ltd.; The molar ratio of brominated PC-1: bisphenol A: tetrabromobisphenol A is 55:45, the viscosity average molecular weight is 26000, and it is homemade; The molar ratio of brominated PC-2: bisphenol A: tetrabromobisphenol A is 50:50, the viscosity average molecular weight is 23000, and it is homemade; The molar ratio of brominated PC-3: bisphenol A: tetrabromobisphenol A is 45:55, the viscosity average molecular weight is 18300, and it is homemade; The molar ratio of brominated PC-4: bisphenol A: tetrabromobisphenol A is 40:60, the viscosity average molecular weight is 14600, and it is homemade; The molar ratio of brominated PC-5: bisphenol A: tetrabromobisphenol A is 65:35, the viscosity average molecular weight is 43000, and it is homemade; The molar ratio of brominated PC-6: bisphenol A: tetrabromobisphenol A is 30:70, the viscosity average molecular weight is 10500, and it is homemade; The preparation method of the above-mentioned brominated PC is as follows: prepare a reactor equipped with an agitator, a condenser, triphosgene and a sodium hydroxide dropping device, add bisphenol A, tetrabromobisphenol A, and 1,2-dichloroethane, add sodium hydroxide solution under stirring, and stir until tetrabromobisphenol A is completely dissolved after adding. Then add a 1,2-dichloroethane solution of triphosgene dropwise. After all the dropwise additions are completed, stir and react at 25-30°C for 2-3 hours. After the reaction is completed, let the solution stand, separate the organic phase, repeatedly wash the organic phase with deionized water, add the organic phase to methanol for precipitation, and obtain brominated PC. The molar ratio of bisphenol A:tetrabromobisphenol A in brominated PC is controlled by controlling the amount and molar ratio of bisphenol A and tetrabromobisphenol A.

[0028] Brominated PC-7: Tetrabromobisphenol A carbonate oligomer, brand BC-58, bromine content 58%, Great Lakes Chemical Company, USA; Toughening agent A: GMA grafted ethylene-methyl acrylate copolymer: GMA grafting rate is 0.5wt%, homemade; Toughening agent B: GMA grafted ethylene-methyl acrylate copolymer: GMA grafting rate is 0.8wt%, homemade; Toughening agent C: GMA grafted ethylene-methyl acrylate copolymer: GMA grafting rate is 1.3wt%, homemade; Toughening agent D: GMA grafted ethylene-methyl acrylate copolymer: GMA grafting rate is 2.0wt%, homemade; Toughening agent E: ethylene-methyl acrylate copolymer: brand ELVALOY AC 1125, DuPont Company, USA; Toughening agent F: GMA grafted ethylene-butyl acrylate copolymer: GMA grafting rate is 1.0wt%, homemade; The method for preparing the above-mentioned self-made toughening agent is as follows: glycidyl methacrylate, initiator (the added amount is 0.3wt% of the total weight of the toughening agent before grafting), dicumyl peroxide, and the toughening agent before grafting are uniformly mixed, and granulated by extrusion through a twin-screw extruder, with a screw temperature of 150-180°C and a length-to-diameter ratio of 44:1. The above-mentioned toughening agents A / B / C / D / F are obtained by controlling the amount of glycidyl methacrylate.

[0029] Toughening agent G: Ethylene-butyl acrylate copolymer: brand ELVALOY AC34035, DuPont, USA; Zinc dihydrogen phosphate: brand BUDIT T21, Budenheim, Germany; Polytetrafluoroethylene: anti-drip agent, commercially available; Antioxidant: 1:1 mixture of RIANOX1010 and RIANOX 168, Tianjin Anlong New Materials Co., Ltd. Embodiment and comparative example Preparation method of flame retardant PBT / polycarbonate composition: according to the ratio, the components are mixed uniformly, and extruded and granulated by a twin-screw extruder to obtain a flame retardant PBT / PC composition, wherein the temperature of zone 1 is 200-220°C, the temperature of zone 2 is 220-230°C, the temperature of zone 3 is 230-240°C, the temperature of zone 4 is 230-240°C, the temperature of zone 5 is 230-240°C, the temperature of zone 6 is 230-240°C, the temperature of zone 7 is 240-250°C, the temperature of zone 8 is 240-250°C, the temperature of zone 9 is 230-240°C, and the main engine speed is 300-400 rpm.

[0030] Various test methods: (1) Flame retardancy: According to UL94 standard, 0.8 mm specimens were injection molded and the flame retardancy was measured using a combustion box.

[0031] (2) -30℃ notched impact strength: After drying the PBT / PC alloy material in a dehumidified drying oven at 120℃ for 4 hours, injection molded notched impact specimens according to standard ASTM D256-2010. The specimens were placed in a low-temperature box at -30℃ for more than 4 hours, and after being taken out, the notched cantilever beam impact strength of the specimens was quickly measured.

[0032] (3) Post-baking shrinkage test: The rectangular plate with a cross is injection molded, the sample size is 220 mm × 60 mm × 2 mm, and the length between the crosses at both ends of the mold is 200.07 mm; 200.07 is the length between the crosses at both ends of the shrinkage plate mold, the unit is mm, and S is the shrinkage rate; specifically, the cross shrinkage plate is placed in a 120°C oven and baked for 2 h. After taking it out and adjusting it for 24 h, the length L2 between the crosses at both ends of the shrinkage plate after baking is measured, and the post-bake shrinkage rate H is calculated according to the following formula; H = (L1-L2) / 200.07*100%; L1 is the length between the crosses at both ends of the shrinkage plate before baking.

[0033] Table 1: Weight parts of each component of flame retardant PBT brominated polycarbonate composition and test results of Examples 1-6 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 PBT Resin-A 40 50 50 50 50 PBT resin-B 60 Brominated PC Label 1 1 1 2 3 4 Brominated PC content 50 35 30 35 35 35 Toughener number A A A A A A Toughener content 10 13 15 13 13 13 Polytetrafluoroethylene 0.3 0.5 0.2 0.5 0.5 0.5 Zinc dihydrogen phosphate 0.1 0.3 0.5 0.3 0.3 0.3 Antioxidants 0.3 0.3 Flame retardant V0 V0 V0 V0 V0 V0 <![CDATA[-30 °C notched impact strength, kJ / m 2 > 8.5 9.6 11.4 9.7 10.1 10.7 Shrinkage rate H,% 0.36 0.49 0.41 0.34 0.31 0.40 It can be seen from Examples 2 / 4-6 that the average molecular weight range of brominated PC and the molar ratio of bisphenol A:tetrabromobisphenol A significantly affect the shrinkage and low-temperature toughness of the composition. The shrinkage is lower and the low-temperature toughness is better in the preferred range.

[0034] Table 2: Weight parts of each component of the flame retardant PBT brominated polycarbonate composition of Examples 7-10 and test results Example 7 Example 8 Example 9 Example 10 PBT Resin-A 50 50 50 50 Brominated PC Label 1 1 1 1 Brominated PC content 35 35 35 35 Toughener number B C D F Toughener content 13 13 13 13 Polytetrafluoroethylene 0.5 0.5 0.5 0.5 Zinc dihydrogen phosphate 0.3 0.3 0.3 0.3 Flame retardant V0 V0 V0 V0 <![CDATA[-30 °C Charpy impact strength, kJ / m 2 > 10.2 9.7 9.1 9.6 Shrinkage rate H,% 0.41 0.38 0.44 0.35 It can be seen from Examples 2 / 7-10 that the low-temperature toughness and shrinkage are better when the toughening agent GMA content is preferred.

[0035] Table 3: Weight parts of each component of comparative flame retardant PBT brominated polycarbonate composition and test results Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 PBT Resin-A 50 50 50 50 50 50 50 Brominated PC Label 5 6 7 1 1 1 1 Brominated PC content 35 35 35 35 35 35 35 Toughener number A A A E G A A Toughener content 13 13 13 13 13 5 23 Polytetrafluoroethylene 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Zinc dihydrogen phosphate 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Flame retardant V0 V0 V0 V0 V0 V0 V2 <![CDATA[-30°C Notched Impact Strength, kJ / m 2 > 7.1 6.4 6.1 5.3 5.4 5.6 10.8 Shrinkage rate H,% 0.69 0.75 0.96 0.77 0.78 0.43 0.48 It can be seen from Comparative Examples 1-2 that if the molar ratio of bisphenol A to tetrabromobisphenol A in brominated PC is not within the range defined in the present invention, both the low-temperature toughness and the shrinkage are poor.

[0036] From Comparative Example 3, it can be seen that when low molecular weight brominated PC is used, both low temperature toughness and shrinkage are worse.

[0037] It can be seen from comparative examples 4 / 5 that the low-temperature toughness and shrinkage are poor when there is no GMA-grafted toughening agent.

[0038] It can be seen from Comparative Example 6 that when the toughening agent content is too low, the low-temperature toughness is poor.

[0039] It can be seen from Comparative Example 7 that when the toughening agent content is too high, the flame retardancy cannot reach V-0.

[0040] It can be seen from the above examples and comparative examples that the flame retardant PBT brominated polycarbonate composition of the present invention has a -30°C notched impact strength of >8 kJ / m 2 , the shrinkage rate H is less than 0.5%.

Claims

1. A flame retardant PBT / brominated polycarbonate composition, characterized in that: By weight, it includes the following components: PBT 40-60 parts; 30-50 parts of brominated polycarbonate; Anti-dripping agent 0.2-0.5 parts; 10-15 parts of glycidyl methacrylate graft toughening agent; The viscosity average molecular weight of the brominated polycarbonate is in the range of 13000-30000, and the molar ratio of bisphenol A to tetrabromobisphenol A is (55-40): (45-60).

2. The flame retardant PBT / brominated polycarbonate composition according to claim 1, characterized in that: The viscosity average molecular weight of the brominated PC is in the range of 17000-24000, and the molar ratio of bisphenol A to tetrabromobisphenol A is (50-45): (50-55).

3. The flame retardant PBT / brominated polycarbonate composition according to claim 1, characterized in that: The glycidyl methacrylate grafted toughening agent is selected from at least one of a glycidyl methacrylate grafted ethylene-methyl acrylate copolymer toughening agent and a glycidyl methacrylate grafted ethylene-butyl acrylate copolymer toughening agent.

4. The flame retardant PBT / brominated polycarbonate composition according to claim 1, characterized in that: In the glycidyl methacrylate grafted toughening agent, the grafting rate of glycidyl methacrylate is 0.4-2.1wt%, preferably 0.8-1.3wt%.

5. The flame retardant PBT / brominated polycarbonate composition according to claim 1, characterized in that: The intrinsic viscosity of the PBT is 1.1-1.5 dl / g.

6. The flame retardant PBT / brominated polycarbonate composition according to claim 1, characterized in that: By weight, the invention also includes 0.05-0.5 parts of an ester exchange inhibitor, wherein the ester exchange inhibitor is selected from at least one of zinc dihydrogen phosphate, sodium hydrogen phosphate, triethanolamine, trimethylstannate, disodium dihydrogen pyrophosphate, and triphenyl phosphate.

7. The flame retardant PBT / brominated polycarbonate composition according to claim 1, characterized in that: The anti-dripping agent is selected from polytetrafluoroethylene.

8. The flame retardant PBT / brominated polycarbonate composition according to claim 1, characterized in that: By weight, the invention also includes 0-2 parts of auxiliary agents, wherein the auxiliary agents are selected from one or more of antioxidants and lubricants.

9. The method for preparing the flame retardant PBT / brominated polycarbonate composition according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: mixing the components uniformly according to the proportion, extruding and granulating through a twin-screw extruder to obtain a flame-retardant PBT / PC composition.

10. Use of the flame retardant PBT / brominated polycarbonate composition according to any one of claims 1 to 8, characterized in that: Used to prepare flame retardant parts.

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