A flame-retardant polycarbonate composite material and its preparation method

Abstract

This invention provides a flame-retardant polycarbonate composite material and its preparation method. The flame-retardant polycarbonate composite material comprises the following raw materials in parts by weight: 100 parts polycarbonate, 3-5 parts organoboron-based flame retardant, 2-3 parts phosphate ester flame retardant, and 0.1-0.5 parts antioxidant. The organoboron-based flame retardant has the structural formula shown in Formula I below. This invention prepares an organoboron-based flame retardant by reacting a triazine aniline derivative and a formylphenylboronic acid acetate derivative. This organoboron-based flame retardant not only significantly improves the flame-retardant properties of the composite material but also retains a high light transmittance value after high-temperature aging, thus achieving a good balance between flame retardancy and transmission performance.

Description

Technical Field

[0001] This invention belongs to the field of flame-retardant polycarbonate technology, specifically relating to a flame-retardant polycarbonate composite material and its preparation method. Background Technology

[0002] Polycarbonate (PC) is a high-molecular-weight polymer containing carbonate groups in its molecular chain. It is renowned for its outstanding optical properties and high impact strength, while also possessing good dimensional stability and electrical insulation properties. It is widely used in automotive, medical, construction, food packaging, aerospace, electronics, and lighting systems. Due to the aromatic structure in its macromolecular chain, PC exhibits better flame retardant properties than PE and PP, with a limiting oxygen index (LOI) of 21-24% and a UL-94 flame retardant rating of V-2. However, in practical applications, PC often needs to meet even more stringent flame retardant requirements.

[0003] Boron-based flame retardants possess characteristics such as high thermal stability, low toxicity, and smoke suppression, aligning with the development trend of halogen-free, non-toxic or low-toxicity, and smoke-suppressing flame retardants. Boron-based flame retardants include inorganic and organic boron-based flame retardants. Inorganic boron-based flame retardants have been studied earlier, with common examples including ammonium pentaborate, sodium metaborate, ammonium fluoroborate, barium metaborate, and zinc borate. For instance, CN106280377B discloses flame-retardant light-stabilized polycarbonate and its preparation method. Composite flame retardants include expandable graphite, nano-carbonyl iron powder, zinc borate, graphene, and silane coupling agents. However, inorganic boron-based flame retardants require a large amount of additive and significantly degrade the mechanical properties of PC. Research on organoboron-based flame retardants is relatively recent. For example, CN112980173B discloses an antibacterial polycarbonate plastic using melamine phosphate borate as the organic flame retardant. Compared to inorganic boron-based flame retardants, it has less impact on the mechanical properties of PC and can effectively improve the flame retardant properties of polycarbonate, while also improving its mechanical properties to some extent. However, studies have found that after long-term operation in high-temperature environments, the composite material develops patches on its surface and its light transmittance decreases. This phenomenon not only affects the aesthetics of the material but also severely limits its application in fields requiring long-term operation in high-temperature environments with strict requirements for light transmittance. It is speculated that organoboron-based flame retardants generally have poor compatibility with polycarbonate. Although they have little impact on the mechanical and optical properties of the composite material at room temperature, long-term operation in high-temperature environments intensifies the molecular motion of organoboron-based flame retardants, leading to increased degrees of freedom in the flame-retardant polycarbonate composite material, resulting in migration and gradual aggregation towards the surface, thus reducing light transmittance.

[0004] Therefore, developing an organic boron-based flame retardant that is highly compatible with polycarbonate, has excellent flame retardant properties, and exhibits stable optical properties at long-term high temperatures is of great significance for expanding the application of reinforced polycarbonate in long-term high-temperature environments. Summary of the Invention

[0005] To address the issue of decreased transmittance performance after prolonged high-temperature operation due to compatibility issues, this invention provides a flame-retardant polycarbonate composite material and its preparation method. An organoboron-based flame retardant is prepared by reacting a triazine aniline derivative and a formylphenylboronic acid acetate derivative. This organoboron-based flame retardant not only significantly improves the flame-retardant performance of the composite material but also retains a high transmittance value after high-temperature aging, thus achieving a good balance between flame retardancy and transmittance performance.

[0006] To achieve the above objectives, the following technical solution is adopted:

[0007] A flame-retardant polycarbonate composite material comprises the following raw materials in parts by weight: 100 parts polycarbonate, 3-5 parts organoboron flame retardant, 2-3 parts phosphate ester flame retardant, and 0.1-0.5 parts antioxidant, wherein the organoboron flame retardant has the following structural formula I: Formula I:

[0008]

[0009] Where R is selected from One or a combination of two of them.

[0010] The organoboron-based flame retardant has a structural formula selected from one or more of the following formulas: I-1, I-2, I-3, and I-4.

[0011]

[0012]

[0013] The organoboron-based flame retardant is prepared by reacting a triazine aniline derivative and a formylphenylboronic acid acetate derivative, wherein the molar ratio of the triazine aniline derivative and the formylphenylboronic acid acetate derivative is 1:3.15-3.3.

[0014] The triazine aniline derivative is selected from one or a combination of two of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 4',4”',4””'-(1,3,5-triazine cyclo-2,4,6-triyl)tri(([1,1'-biphenyl]-4-amine)); the formylphenylboronic acid acetate derivative is selected from one or a combination of two of 4-formylphenylboronic acid methyliminodiacetic acid and 3-formylphenylboronic acid methyliminodiacetic acid.

[0015] Specifically, the organoboron-based flame retardant is prepared by a method comprising the following steps:

[0016] Under an inert atmosphere, an organic solvent, a triazine aniline derivative, and a formylphenylboronic acid acetate derivative are added to a reaction vessel and stirred until completely dissolved. The mixture is then heated to reflux for reaction. After the reaction is complete, the mixture is cooled to room temperature, and an organic alcohol is added until no precipitate is formed. The mixture is then filtered, washed, and dried to obtain an organoboron-based flame retardant.

[0017] The organic solvent is selected from one or a combination of two or more of benzene and toluene. The reaction time is 1-3 hours. The organic alcohol is selected from one or a combination of two or more of methanol, ethanol, and isopropanol. The washing is performed 1-3 times with the organic alcohol. The drying is performed at 60-100°C to constant weight.

[0018] The phosphate flame retardant is selected from one or a combination of two or more of the following: triethyl phosphate, tributyl phosphate, triisooctyl phosphate, tri(2-butoxyethyl) phosphate, diphenylisooctyl phosphate, diphenylisodecyl phosphate, triphenyl phosphate, diphenyltoluene phosphate, tricresyl phosphate, tri(xyl) phosphate, diphenylisopropylphenyl phosphate, and diphenyl(xyl) phosphate.

[0019] The polycarbonate is a bisphenol A type polycarbonate with a melt index of 8-15 g / 10 min at 300℃ and 1.2 kg.

[0020] The antioxidant is selected from one or a combination of two or more of antioxidants 1010, antioxidant 168, and antioxidant 164.

[0021] A method for preparing a flame-retardant polycarbonate composite material includes the following steps:

[0022] Polycarbonate, organoboron-based flame retardant, phosphate ester flame retardant, and antioxidant are mixed evenly and then fed into a twin-screw extruder for extrusion, granulation, and drying to obtain a flame-retardant polycarbonate composite material.

[0023] The twin-screw extruder has a screw speed of 20-100 r / min, a screw diameter of 10-40 mm, a length-to-diameter ratio of (12-40):1, and an extruder barrel temperature of 200-300℃.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] This invention prepares an organoboron-based flame retardant by reacting a triazine aniline derivative and a formylphenylboronic acid acetate derivative. This organoboron-based flame retardant not only significantly improves the flame retardant properties of the composite material, but also retains a high light transmittance value after high-temperature aging, thus achieving a good balance between flame retardancy and transmission performance.

[0026] The inventors discovered that triphenyl phosphate has a significant synergistic effect with organoboron-based flame retardants in reducing the heat release rate and increasing the LOI value. Detailed Implementation

[0027] The present invention will be further described below with reference to specific embodiments, but is not limited to the contents of the specification. Unless otherwise specified, all "parts" mentioned in the embodiments of the present invention are parts by weight. All reagents used are commercially available in the art.

[0028] Bisphenol A polycarbonate was purchased from Covestro, grade 2800, with a melt index of 10 g / 10 min.

[0029] Example 1

[0030] 1) Under a nitrogen atmosphere, 200 mL of benzene, 0.1 mol of 4',4”',4””'-(1,3,5-triazinecyclo-2,4,6-triyl)tris(([1,1'-biphenyl]-4-amine)) and 0.315 mol of 4-formylphenylboronic acid methyliminodiacetic acid ester were added to the reaction vessel and stirred until completely dissolved. The mixture was heated to reflux and reacted for 3 h. After the reaction was completed, the mixture was cooled to room temperature, and isopropanol was added until no new precipitate was formed. The mixture was filtered, the filter residue was washed three times with ethanol, and dried at 100 °C to obtain an organoboron-based flame retardant.

[0031] 2) Mix 1000g of polycarbonate Covestro 2800, 50g of organoboron flame retardant, 20g of triphenyl phosphate, and 5g of antioxidant 1010 evenly, then add the mixture to a twin-screw extruder for extrusion, granulation, and drying to obtain a flame-retardant polycarbonate composite material.

[0032] The twin-screw extruder has a screw speed of 70 r / min, a screw diameter of 20 mm, a length-to-diameter ratio of 20:1, and extruder barrel temperatures of 240℃, 260℃, 270℃, 265℃, and 260℃.

[0033] Example 2

[0034] The rest is the same as in Example 1, except that in step 1), 4',4”',4””'-(1,3,5-triazinecyclo-2,4,6-triyl)tri(([1,1'-biphenyl]-4-amine)) is replaced with an equimolar amount of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine.

[0035] Example 3

[0036] The rest is the same as in Example 1, except that in step 1), 4-formylphenylboronic acid methyliminodiacetic acid ester is replaced with an equimolar amount of 3-formylphenylboronic acid methyliminodiacetic acid ester.

[0037] Example 4

[0038] The rest is the same as in Example 1, except that in step 2), the amount of organic boron flame retardant used is 30g.

[0039] Example 5

[0040] 1) Under a nitrogen atmosphere, 200 mL of benzene, 0.1 mol of 4',4”',4””'-(1,3,5-triazinecyclo-2,4,6-triyl)tris(([1,1'-biphenyl]-4-amine)) and 0.33 mol of 4-formylphenylboronic acid methyliminodiacetic acid ester were added to the reaction vessel and stirred until completely dissolved. The mixture was heated to reflux and reacted for 3 h. After the reaction was completed, the mixture was cooled to room temperature, and isopropanol was added until no precipitate was formed. The mixture was filtered, the filter residue was washed three times with ethanol, and dried at 100 °C to obtain an organoboron-based flame retardant.

[0041] 2) Mix 1000g of polycarbonate Covestro 2800, 30g of organoboron flame retardant, 30g of triphenyl phosphate, and 5g of antioxidant 1010 evenly, then add the mixture to a twin-screw extruder for extrusion, granulation, and drying to obtain a flame-retardant polycarbonate composite material.

[0042] The twin-screw extruder has a screw speed of 70 r / min, a screw diameter of 20 mm, a length-to-diameter ratio of 20:1, and extruder barrel temperatures of 250℃, 260℃, 270℃, 265℃, and 260℃.

[0043] Example 6

[0044] The rest is the same as in Example 1, except that the amount of triphenyl phosphate used in step 2) is 30g.

[0045] Comparative Example 1

[0046] The rest is the same as in Example 1, except that in step 2), the organic boron-based flame retardant is replaced with an equal mass of melamine phosphate borate.

[0047] Melamine phosphate borate was prepared according to Zhao Aiming's "Synthesis of Melamine Phosphate Borate Flame Retardant" (Shandong Chemical Industry, Vol. 38, No. 12, 2009). The preparation method of melamine phosphate borate includes the following steps: 17.02g of 85wt% H3PO4 was added to 50mL of water, stirred evenly, and heated to 50℃. Then 18.6g of melamine was added and stirred evenly. The mixture was reacted at 50℃ for 2h. The precipitate was collected by centrifugation, washed, and dried to obtain melamine phosphate. 6.70g of boric acid and 16.2g of melamine phosphate were added to 45mL of water, stirred evenly, and heated to 80℃ for 3h. The precipitate was collected by centrifugation, washed, and dried to obtain melamine phosphate borate.

[0048] Comparative Example 2

[0049] The rest is the same as in Example 1, except that in step 2), triphenyl phosphate is not added.

[0050] Comparative Example 3

[0051] The rest is the same as in Example 1, except that in step 2), the amount of organic boron flame retardant used is 25g.

[0052] Comparative Example 4

[0053] The rest is the same as in Example 1, except that the amount of triphenyl phosphate used in step 2) is 35g.

[0054] The flame-retardant polycarbonate composite materials prepared in the above examples and comparative examples were tested for the following properties:

[0055] Light transmittance: Tested according to ASTM D1003.

[0056] Thermal aging: Refer to GB / T 7141-2008 Plastics thermal aging test method, and remeasure the light transmittance after aging at 130℃ for 200 hours in the aging test chamber.

[0057] Flame retardancy rating test: The test shall be conducted in accordance with GB / T2408-2008 "Test of flammability of plastics - Horizontal and vertical methods".

[0058] LOI: Tested according to ASTM D2863.

[0059] Conical calorimetry test: Following ISO 5660-1, the test was conducted on an injection-molded plate with dimensions of 100mm × 100mm × 3.2mm, at 50kW / m². 2 Peak heat release rate (PHRR) data were collected under heat flux conditions.

[0060] Table 1 Performance Test Results

[0061] project LOI UL-94 Light transmittance % after heat aging Peak heat release rate (PHRR) Example 1 36.4 V0 90 251 Example 2 30.5 V0 85 255 Example 3 36.3 V0 87 251 Example 4 28.7 V0 90 280 Example 5 32.8 V0 90 278 Example 6 33.9 V0 90 272 Comparative Example 1 32.6 V0 76 346 Comparative Example 2 26.2 V1 88 414 Comparative Example 3 21.7 V1 89 313 Comparative Example 4 38.1 V0 90 382

[0062] The transmittance test results after thermal aging show that the organic boron flame retardant prepared in this invention has good compatibility with the composite material and minimal transmittance loss after high-temperature aging.

[0063] Table 1 shows that Triphenyl phosphate has a significant synergistic effect with organoboron-based flame retardants in reducing the heat release rate and increasing the LOI value. This is presumably because an appropriate amount of Triphenyl phosphate can form a char layer with the organoboron-based flame retardant, reducing the transmission of combustible gases in the flame. Simultaneously, it generates phosphorus and phosphoroyl radicals, which play a free radical scavenging role, thereby effectively inhibiting heat release during combustion. However, the heat release rate increases when the amount of Triphenyl phosphate is higher. This is presumably because the plasticizing effect of excessive Triphenyl phosphate causes a decrease in melt viscosity, reducing the strength of the char layer and thus resulting in a higher heat release rate.

[0064] The above detailed description is a specific description of one of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included within the scope of the technical solution of the present invention.

Claims

1. A flame-retardant polycarbonate composite material, characterized in that, The raw materials include the following parts by weight: 100 parts polycarbonate, 3-5 parts organoboron flame retardant, 2-3 parts triphenyl phosphate, and 0.1-0.5 parts antioxidant. The organoboron flame retardant has the following structural formula (Formula I): Formula I: Where R is selected from One or a combination of two of them.

2. The flame-retardant polycarbonate composite material according to claim 1, characterized in that, The organoboron-based flame retardant has a structural formula selected from one or more of the following formulas: I-1, I-2, I-3, and I-4. Formula I-1: Formula I-2: Formula I-3: Formula I-4:

3. The flame-retardant polycarbonate composite material according to claim 1, characterized in that, The organoboron-based flame retardant is prepared by reacting a triazine aniline derivative and a formylphenylboronic acid acetate derivative, wherein the molar ratio of the triazine aniline derivative and the formylphenylboronic acid acetate derivative is 1:3.15-3.

3.

4. The flame-retardant polycarbonate composite material according to claim 3, characterized in that, The triazine aniline derivative is selected from one or a combination of two of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 4',4”',4””'-(1,3,5-triazine cyclo-2,4,6-triyl)tri(([1,1'-biphenyl]-4-amine)).

5. The flame-retardant polycarbonate composite material according to claim 3, characterized in that, The formylphenylboronic acid acetate derivative is selected from one or a combination of two of 4-formylphenylboronic acid methyliminodiacetic acid ester and 3-formylphenylboronic acid methyliminodiacetic acid ester.

6. The flame-retardant polycarbonate composite material according to claim 1, characterized in that, The organoboron-based flame retardant is prepared by a method comprising the following steps: Under an inert atmosphere, an organic solvent, a triazine aniline derivative, and a formylphenylboronic acid acetate derivative are added to a reaction vessel and stirred until completely dissolved. The mixture is then heated to reflux for reaction. After the reaction is complete, the mixture is cooled to room temperature, and an organic alcohol is added until no precipitate is formed. The mixture is then filtered, washed, and dried to obtain an organoboron-based flame retardant.

7. The flame-retardant polycarbonate composite material according to claim 6, characterized in that, The organic solvent is selected from one or more of benzene and toluene, and the reaction time is 1-3 hours.

8. The flame-retardant polycarbonate composite material according to claim 1, characterized in that, The polycarbonate is a bisphenol A type polycarbonate with a melt index of 8-15 g / 10 min at 300℃ and 1.2 kg.

9. A method for preparing the flame-retardant polycarbonate composite material according to any one of claims 1-8, characterized in that, Includes the following steps: Polycarbonate, organoboron-based flame retardant, phosphate ester flame retardant, and antioxidant are mixed evenly, and then fed into a twin-screw extruder for extrusion, granulation, and drying to obtain a flame-retardant polycarbonate composite material.

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