Polycarbonate composite material as well as preparation method and application thereof

Abstract

The invention discloses a high-CTI (comparative tracking index) flame-retardant polycarbonate composite material which comprises the following components in parts by weight: 70-80 parts of polycarbonate; 8-12 parts of a phosphate flame retardant; 3-7 parts of low-melting-point glass powder; 7-15 parts of titanium dioxide; and more than or equal to 80 mol% of end groups in the polycarbonate are terminated. Through cooperation of the phosphate flame retardant, the low-melting-point glass powder and the titanium dioxide, 1.5 mm V-0 flame retardance and even 1.0 mm flame retardance can be achieved on the premise that fluorine-containing anti-dripping agents such as PFAS are not contained and low filler filling is achieved, and meanwhile the CTI larger than or equal to 600 V is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to a polycarbonate composite material and a preparation method and application thereof. Background Art

[0002] Polycarbonate (PC) is a common engineering plastic with excellent mechanical properties and heat resistance, and has the advantages of high strength and elastic modulus, high impact strength, high heat resistance, free dyeing, low molding shrinkage, good dimensional stability, good fatigue resistance, etc. Modified PC products are widely used in many fields such as automotive parts, industrial machinery parts, optical disks, packaging, office equipment such as computers, medical and health care, films, leisure and protective equipment, etc.

[0003] In some electronic and electrical fields, high tracking resistance and PFAS Free have become hot spots and difficulties in the research and development of flame-retardant PC products. Especially in the rapidly developing photovoltaic and new energy industries, higher requirements are placed on the tracking resistance of materials, requiring CTI to be greater than or equal to 600V, and the flame retardancy level to reach 1.5mmV-0. PFAS is a class of organic compounds with multiple fluorine atoms on the alkyl chain, including compounds such as perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS) and hexafluoropropylene oxide dimer acid (GenX); because the carbon-fluorine bond is one of the strongest bonds, it is chemically inert and resistant to high temperatures, and these chemicals are not easily degraded in the environment. Due to their biological persistence, they are often called "forever chemicals." PTFE is also a type of PFAS, and it plays a very important role in flame-retardant PC as an anti-dripping agent to enable PC to reach a V-0 flame retardancy level. However, since PFAS can persist in the environment for a long time, it is almost impossible to be biodegraded. Therefore, PFAS is also regarded as a new type of artificially synthesized persistent organic pollutant, and PFAS Free has become a major trend in the future development of flame-retardant PC.

[0004] In order to meet the halogen-free flame retardant requirements of polycarbonate, it is generally achieved by adding sulfonate flame retardants or aromatic phosphate flame retardants to PTFE. However, PFAS (including PTFE) has harmful effects on the human body, such as interfering with hormone levels, inhibiting growth and development, and increasing the risk of cancer. The amount of sulfonate flame retardant (PFBS) added is controlled by Reach Environmental Protection, which makes it difficult to achieve thin-wall flame retardant effects. Moreover, the addition of this flame retardant usually catalyzes polycarbonate to carbonize, and therefore often deteriorates the CTI performance of the system. The research on PFAS Free flame retardant PC high CTI technology has become increasingly important. Existing technologies can either achieve high CTI but contain PFAS flame retardant, or can be PFAS Free flame retardant but cannot achieve high CTI. At present, there is no flame retardant PC with high tracking resistance and fluorine-free (PFAS Free).

[0005] Patent CN117327382A discloses a fluorine-free halogen-free flame-retardant PC plastic and a preparation method thereof. Compared with the prior art, the present invention solves the problem that the halogen-free flame-retardant V0 grade PC material has a potential PFAS environmental risk due to the addition of PTFE fluorine-containing anti-drip agent, and the thin-wall flame-retardant V0 does not meet the standard without adding PTFE-free anti-drip agent. However, this type of fluorine-free flame-retardant PC cannot achieve the purpose of high CTI. Summary of the invention

[0006] The object of the present invention is to overcome the above-mentioned technical defects and provide a PFAS Free polycarbonate composite material with 1.5mmV-0 flame retardancy or even 1.0mmV-0 flame retardancy and ≥600VCTI.

[0007] The present invention is achieved through the following technical solutions: A polycarbonate composite material, comprising the following components in parts by weight: Polycarbonate 70-80 parts; 8-12 parts of phosphate flame retardant; 3-7 parts of low melting point glass powder; 7-15 parts of titanium dioxide; ≥80 mol % of the terminal groups in the polycarbonate are capped.

[0008] The content of polycarbonate can be 70 parts, 71 parts, 72 parts, 73 parts, 74 parts, 75 parts, 76 parts, 77 parts, 78 parts, 79 parts, 80 parts, etc., the content of phosphate flame retardant can be 8 parts, 8.5 parts, 9 parts, 9.5 parts, 10 parts, 10.5 parts, 11 parts, 11.5 parts, 12 parts, etc., and the content of low melting point glass powder can be 3 parts, 3.5 parts, 4 parts, 4 .5 parts, 5.0 parts, 5.5 parts, 6.0 parts, 6.5 parts, 7.0 parts, etc., the content of titanium dioxide can be 7 parts, 7.5 parts, 8.0 parts, 8.5 parts, 9.0 parts, 9.5 parts, 10.0 parts, 10.5 parts, 11.0 parts, 11.5 parts, 12.0 parts, 12.5 parts, 13.0 parts, 13.5 parts, 14.0 parts, 14.5 parts, 15 parts, etc.

[0009] In the polycarbonate composite material of the present invention, the content of polycarbonate in the total weight is not less than 60wt%.

[0010] The polycarbonate is an aromatic polycarbonate with a weight average molecular weight ranging from 25000 to 55000, preferably from 30000 to 50000, and the testing method is gel permeation chromatography (GPC).

[0011] The aromatic polycarbonate is bisphenol A polycarbonate.

[0012] The end-capping rate of the polycarbonate in the present invention can be 80 mol%-100 mol%, and it has been experimentally confirmed that it can be 81 mol%, 82 mol%, 83 mol%, 84 mol%, 85 mol%, 86 mol%, 87 mol%, 88 mol%, 89 mol%, 90 mol%, 91 mol%, 92 mol%, 93 mol%, 94 mol%, 95 mol%, 96 mol%, 97 mol%, 98 mol%, 99 mol%, etc. Preferably, ≥ 90 mol% of the end groups in the polycarbonate are end-capped.

[0013] The end-capping agent is selected from phenol or its derivatives. Specifically, the end-capping agent is selected from at least one of phenol, p-tert-butylphenol and dicumylphenol.

[0014] Polycarbonate can be a commercial product or can be obtained by self-production, and the self-production method is as follows: First, clean the inside of the kettle and polish it, and connect the device. Then conduct an airtightness inspection. After the inspection is complete, add a certain amount of diphenyl carbonate (DPC) and bisphenol A (BPA) (molar ratio 1:1.03-1.08) into the steel reactor. Open the nitrogen valve and introduce high-purity nitrogen to replace the air in the kettle at least 3 times. Turn on the heating button and set the temperature to 135-145℃. After the raw materials are completely melted, start stirring for 1-10 minutes to mix the materials evenly. Then, add the transesterification catalyst TBAOH addition amount (4-6)*10 -4 mol / molBPA, mix for 1-10min, set the temperature program to 170~180℃ and turn on the vacuum oil pump, control the regulating valve to adjust the pressure in the kettle to 20-30kPa, react for 5-15min, add the end-capping agent and react for 1-10min (and adjust the end-capping level by adding the amount of end-capping agent, the end-capping level is about 65% when the addition amount is 0 mol / molBPA, and the addition amount is 5*10 -5 mol / mol BPA, the end-capping level is about 80%, 1*10 -4 mol / mol BPA, the end-capping level is about 90%, 5*10 -4mol / mol BPA when the end-capping level is about 95%). Raise the temperature to 205-215℃, adjust the pressure in the kettle to 15-25kPa, maintain for 10-30min, then reduce the pressure to 10-20kPa, and maintain for 10-30min. Turn off the vacuum pump and agitator, restore the air pressure, add the polycondensation catalyst under the protection of nitrogen, then turn on the stirring device and stir for 1-5min, continue to raise the temperature to 235-245℃, reduce the pressure to 5-15KPa, maintain for 10-30min, and continue to reduce the pressure to 1-10kPa at this temperature, and maintain for 5-15min. When the temperature rises to the set polycondensation temperature, reduce the pressure to 0.5-1.5kPa and maintain for 5-15min. Then reduce the pressure to 0.1-0.5kPa and heat to the set discharge temperature within 5-15min. Then take out the product from the bottom of the kettle after water cooling, grind, dry, and test.

[0015] The end-capping rate test method of polycarbonate is: the end-capping level is determined based on the UV measurement results of the amount of terminal OH groups, and then the end-capping level is calculated according to the following formula combined with the number average molecular weight; when using spectrophotometry to determine hydroxyl radicals, salicylic acid is the most commonly used scavenger, and its reaction products with hydroxyl radicals are 2.3-dihydroxybenzoic acid and 2.5-dihydroxybenzoic acid. The amount of 2.3-dihydroxybenzoic acid generated is in a 1:1 relationship with the amount of free radicals reacted with ·OH, thereby achieving the purpose of indirectly determining hydroxyl groups. The test instrument is a UV spectrophotometer.

[0016]

[0017] Wherein %EC is the encapsulation rate, ppmOH is the amount of hydroxyl end groups per million parts by weight, and Mn is the number average molecular weight of the polycarbonate based on a polycarbonate standard.

[0018] The endcapping level is defined as the mole percent of polycarbonate end groups that are not hydroxyl groups and can be calculated according to Formula I from the amount of terminal OH groups in the polycarbonate and the number average molecular weight (Mn).

[0019] The melting point of the low melting point glass powder is 350-800° C., preferably 450-750° C. The melting point of the low melting point glass powder can be 350° C., 395° C., 400° C., 450° C., 500° C., 550° C., 600° C., 650° C., 700° C., 706° C., 750° C., 800° C., etc. The median particle size range of the low melting point glass powder is 800 mesh to 6000 mesh.

[0020] The phosphate flame retardant is selected from at least one of trimethyl phosphate, triethyl phosphate, triphenyl phosphate and resorcinol bisphosphate.

[0021] The average particle size of the titanium dioxide is 5-100 nm, preferably 10-50 nm. The average particle size of the titanium dioxide is measured by a laser particle size analyzer and can be 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, etc.

[0022] It is possible to add 0-10 parts of filler according to actual needs, wherein the filler is selected from at least one of mica, wollastonite, kaolin, talc, silicon dioxide, montmorillonite and glass fiber. The filler content can be 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, etc.

[0023] It is possible to choose whether to add 0-10 parts of auxiliary agents according to actual needs, and the auxiliary agents are selected from at least one of antioxidants, lubricants, and toughening agents. The content of antioxidants can be 0.5 parts, 0.8 parts, 1.0 parts, the content of lubricants can be 0.5 parts, 0.8 parts, 1.0 parts, and the content of toughening agents can be 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, etc.

[0024] The preparation method of the polycarbonate composite material of the present invention comprises the following steps: mixing the components uniformly according to the proportion, and extruding and granulating through a twin-screw extruder to obtain the polycarbonate composite material.

[0025] The polycarbonate composite material of the invention is used in the field of electronic appliances.

[0026] The polycarbonate composite material of the present invention does not contain PFAS, and the PFAS is one or more of perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), hexafluoropropylene oxide dimer acid (GenX), and polytetrafluoroethylene.

[0027] The present invention has the following beneficial effects: First, the present invention uses low-melting-point glass powder and inorganic fillers such as titanium dioxide, which are insulating materials with high resistivity and low conductivity, and can block the conduction of current. In addition, when the material is damaged by electrical tracking, the material is heated so that the titanium dioxide and low-melting-point glass powder work together to form a large inorganic insulation resistance, directly cutting off the conductive carbon path. Compared with PC, inorganic fillers have higher thermal conductivity and can disperse heat to a certain extent.

[0028] Second, TiO2 can reflect, scatter, and absorb ultraviolet rays due to its small particle size and high activity. The blocking of ultraviolet rays in the long-wave region is mainly scattering, while the blocking of ultraviolet rays in the medium-wave region is mainly absorption. Therefore, adding titanium dioxide can effectively shield ultraviolet rays, reduce the rate of PC degradation into carbon caused by ultraviolet rays, and improve the material's resistance to leakage tracking.

[0029] Third, highly end-capped polycarbonate can significantly reduce the degradation rate of PC during the CTI test, especially the degradation by water and electrolyte solution, thereby slowing down the formation of conductive carbon paths, and further improving the CTI value when the surface of the PC material is contaminated by water or electrolyte solution.

[0030] Fourth, the present invention utilizes phosphate flame retardant to promote polymer dehydration and decomposition in the polymer decomposition stage at the initial stage of fire, thereby reducing the amount of combustible gas generated by polymer thermal decomposition, and the generated carbon layer can also isolate external air and heat. At the same time, the combined effect of low melting point glass powder, inorganic filler and phosphorus flame retardant accelerates the speed of forming a non-conductive flame-retardant carbon layer when the PC material burns, and the formed non-conductive flame-retardant carbon layer has a certain hardness and strength, so that the melt is not easy to drip when the PC material burns, and a flame retardancy of 1.5mmV-0 is obtained, and even the preferred solution can reach 1.0mmV-0. DETAILED DESCRIPTION

[0031] 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.

[0032] The sources of raw materials used in the examples and comparative examples of the present invention are as follows: Polycarbonate A: The end-capping agent is p-tert-butylphenol, the end-capping amount is 81.2%, the weight average molecular weight is 35100, and it is homemade; Polycarbonate B: The end-capping agent is p-tert-butylphenol, the end-capping amount is 90.6%, the weight average molecular weight is 36300, and it is homemade; Polycarbonate C: The end-capping agent is p-tert-butylphenol, the end-capping amount is 95.7%, the weight average molecular weight is 33600, and it is homemade; Polycarbonate D: The end-capping agent is p-tert-butylphenol, the end-capping amount is 80.3%, the weight average molecular weight is 49000, and it is homemade; Polycarbonate E: the end-capping agent is p-tert-butylphenol, the end-capping amount is 65.0%, the weight average molecular weight is 39400, and it is homemade; Polycarbonate F: G1010-F, weight average molecular weight 45000, end-capping rate 74.8%, Zhejiang Petrochemical; First, clean the kettle and polish it, and connect the device. Then conduct an airtightness inspection. After the inspection is complete, add a certain amount of diphenyl carbonate (DPC) and bisphenol A (BPA) (molar ratio 1:1.06) into the steel reactor, open the nitrogen valve and introduce high-purity nitrogen to replace the air in the kettle at least 3 times. Turn on the heating button and set the temperature to 140°C. After the raw materials are completely melted, start stirring for 5 minutes to mix the materials evenly. Then, add the ester exchange catalyst TBAOH at an addition amount of 5*10 -4 mol / molBPA, mix for 5 minutes, set the temperature program to 170~180℃ and turn on the vacuum oil pump, control the regulating valve to adjust the pressure in the kettle to 25kPa, react for 10 minutes, add the end-capping agent and react for 5 minutes (and adjust the end-capping level by adding the end-capping agent. When the addition amount is 0 mol / molBPA, the end-capping level is about 65%, and when the addition amount is 5*10 -5 mol / mol BPA, the end-capping level is about 80%, 1*10 -4 mol / mol BPA, the end-capping level is about 90%, 5*10 -4 mol / mol BPA when the end-capping level is about 95%). Raise the temperature to 210℃, adjust the pressure in the kettle to 20kPa, maintain for 20min, then reduce the pressure to 15kPa, and maintain for 20min. Turn off the vacuum pump and agitator, restore the air pressure, add the polycondensation catalyst under the protection of nitrogen, turn on the agitator and stir for 2min, continue to raise the temperature to 240℃, reduce the pressure to 10KPa, maintain for 20min, and continue to reduce the pressure to 5kPa at this temperature, and maintain for 10min. When the temperature rises to the set polycondensation temperature, reduce the pressure to 1kPa and maintain for 10min. Then reduce the pressure to 0.5kPa and raise the temperature to the set discharge temperature within 10min. Then take out the product from the bottom of the kettle after water cooling, grind, dry and test.

[0033] Trimethyl phosphate: Trimethyl phosphate (TMP), Tianchang New Material Technology Co., Ltd.; Triethyl phosphate: triethyl phosphate (TEP), Tianchang New Material Technology Co., Ltd.; Triphenyl phosphate: triphenyl phosphate (TPP), Tianchang New Material Technology Co., Ltd.; Resorcinol bisphosphate: Resorcinol bisphosphate (RDP), Yarui Chemical Co., Ltd.; Titanium dioxide A: Titanium dioxide 2233, average particle size 30nm, Connos; Titanium dioxide B: PGNR-508, average particle size 43.8nm, vanadium titanium; Low melting point glass powder A: FD56, melting point 395℃, median particle size 2000 mesh, Anmi micro-nano; Low melting point glass powder B: FD61, melting point 450℃, median particle size 2000 mesh, Anmi micro-nano; Low melting point glass powder C: FD86, melting point 706℃, median particle size 2000 mesh, ANMI micro-nano; Low melting point glass powder D: FD106, melting point 880℃, median particle size 2000 mesh, ANMI micro-nano; Mica powder: GM-5, Ge Rui, the average particle size of the raw material is 24.3nm obtained by screening.

[0034] Lubricant: GLYCOLUBE-P, Lonza, USA; Embodiment and comparative example The preparation method of the high CTI flame retardant polycarbonate composite material is as follows: according to the ratio, each component is mixed evenly, and extruded and granulated by a twin-screw extruder to obtain the high CTI flame retardant polycarbonate composite material; the barrel temperature range is 250-290°C.

[0035] Various test methods: (1) Flame retardancy: refer to the vertical burning test standard of UL94; (2) CTI: Reference standard ASTM D3638; Table 1: Weight content and test results of polycarbonate composite materials of Examples 1-6 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Polycarbonate Marking A B C D A A Polycarbonate content 75 75 75 75 70 80 Trimethyl phosphate 10 10 10 10 12 8 Low melting point glass powder A 5 5 5 5 7 3 Titanium Dioxide A 10 10 10 10 7 15 Mica powder 5 Lubricants 0.5 0.5 0.5 0.5 Flame retardant 2.0mm V-0 V-0 V-0 V-0 V-0 V-0 Flame retardant 1.5mm V-0 V-0 V-0 V-0 V-0 V-0 Flame retardant 1.0mm V-2 V-2 V-2 V-2 V-2 V-2 CTI, V 600V 625V 625V 600V 600V 600V It can be seen from Examples 1-4 that the CTI value is higher when the end-capping rate of the polycarbonate is within a preferred range.

[0036] Table 2: Weight content and test results of polycarbonate composite materials of Examples 7-12 Example 7 Example 8 Example 9 Example 10 Embodiment 11 Example 12 Polycarbonate A 75 75 75 75 75 75 Trimethyl phosphate 10 10 10 Triethyl phosphate 10 Triphenyl phosphate 10 Resorcinol bisphosphate 10 Low melting point glass powder A 5 5 5 5 Low melting point glass powder B 5 Low melting point glass powder C 5 Titanium Dioxide A 10 10 10 10 10 Titanium Dioxide B 10 Lubricants 0.5 0.5 0.5 0.5 0.5 0.5 Flame retardant 2.0mm V-0 V-0 V-0 V-0 V-0 V-0 Flame retardant 1.5mm V-0 V-0 V-0 V-0 V-0 V-0 Flame retardant 1.0mm V-2 V-2 V-2 V-0 V-0 V-2 CTI, V 600V 600V 600V 650V 625V 600V It can be seen from Examples 1 / 10 / 11 that the CTI value of the preferred low-melting-point glass powder is higher at the melting point.

[0037] Table 3: Comparative Example Polycarbonate Composite Material Content by Weight and Test Results Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 Polycarbonate A 75 75 75 75 75 75 Polycarbonate E 75 Polycarbonate F 75 Trimethyl phosphate 10 10 10 10 10 10 10 10 Low melting point glass powder A 5 5 5 0 2 10 5 Low melting point glass powder D 5 Titanium Dioxide A 10 10 0 10 5 20 10 Mica powder 10 Lubricants 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Flame retardant 2.0mm V-0 V-0 V-2 V-2 V-0 V-0 V-0 V-0 Flame retardant 1.5mm V-2 V-1 V-2 V-2 V-0 V-0 V-0 V-0 Flame retardant 1.0mm V-2 V-2 V-2 V-2 Lower than V-2 V-2 V-0 V-2 CTI, V 500V 500V 500V 550V 525V 500V 500V 550V It can be seen from Comparative Examples 1 / 2 that the CTI is lower when a polycarbonate having an end-capping rate not within the scope of the present invention is selected.

[0038] It can be seen from Comparative Example 3 that if titanium dioxide is not contained, the flame retardancy decreases and the CTI is low.

[0039] It can be seen from Comparative Example 4 that if the low-melting point glass powder is not contained, the flame retardancy decreases and the CTI is low.

[0040] It can be seen from Comparative Example 5 that if the content of low-melting-point glass powder and titanium dioxide is too low, the CTI is low.

[0041] It can be seen from Comparative Example 6 that if the content of low-melting-point glass powder and titanium dioxide is too high, the CTI is very low.

[0042] It can be seen from Comparative Example 7 that when the melting point of the low-melting-point glass powder is too high, the CTI decreases.

[0043] It can be seen from Comparative Example 8 that when mica powder is used instead of titanium dioxide, the CTI is lower.

[0044] It can be seen from the above embodiments that the polycarbonate composite material of the present invention has 2.0 mm and 1.5 mm V-0 flame retardancy, 1.0 mm V-2 flame retardancy, and CTI≥600V.

Claims

1. A polycarbonate composite material, characterized in that: By weight, it includes the following components: Polycarbonate 70-80 parts; 8-12 parts of phosphate flame retardant; 3-7 parts of low melting point glass powder; 7-15 parts of titanium dioxide; ≥80 mol % of the terminal groups in the polycarbonate are capped.

2. The polycarbonate composite material according to claim 1, characterized in that: The polycarbonate is an aromatic polycarbonate, and preferably has a weight average molecular weight in the range of 30,000-50,000.

3. The polycarbonate composite material according to claim 1, characterized in that: ≥90 mol% of the end groups in the polycarbonate are capped and / or the capping agent is selected from phenol or its derivatives.

4. The polycarbonate composite material according to claim 1, characterized in that: The melting point of the low-melting-point glass powder is 350-800°C, preferably 450-750°C.

5. The polycarbonate composite material according to claim 1, characterized in that: The phosphate flame retardant is selected from at least one of trimethyl phosphate, triethyl phosphate, triphenyl phosphate and resorcinol bisphosphate.

6. The polycarbonate composite material according to claim 1, characterized in that: The average particle size of the titanium dioxide is 10-50nm.

7. The polycarbonate composite material according to claim 1, characterized in that: By weight, the invention further comprises 0-10 parts of filler, wherein the filler is selected from at least one of mica, wollastonite, kaolin, talcum powder, silicon dioxide, montmorillonite and glass fiber.

8. The polycarbonate composite material according to claim 1, characterized in that: The invention also includes 0-10 parts of auxiliary agents by weight, wherein the auxiliary agents are selected from at least one of antioxidants, lubricants and toughening agents.

9. The method for preparing the polycarbonate composite material 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 polycarbonate composite material.

10. Use of the polycarbonate composite material according to any one of claims 1 to 8, characterized in that: Used in the field of electronics and electrical appliances.