Fluoride-free halogen-free flame-retardant polycarbonate composition and preparation method thereof

Abstract

The invention discloses a fluoride-free halogen-free flame-retardant polycarbonate composition and a preparation method thereof. The fluoride-free halogen-free flame-retardant polycarbonate composition is prepared from the following components in parts by weight: 70 to 90 parts of polycarbonate resin, 0.1 to 10 parts of a halogen-free flame retardant, 0 to 3 parts of a synergistic flame retardant, 0 to 2 parts of gas-phase nano silicon dioxide, 0 to 6 parts of a fluoride-free anti-dripping agent and 0.1 to 2 parts of an auxiliary agent. The fluorine-free anti-dripping agent is introduced to improve the melt strength, and meanwhile, the synergistic flame retardant is introduced to promote a polymer to form a carbon layer, so that the flame-retardant efficiency is improved. According to the method provided by the invention, the problems that potential PFAS environmental protection risk is caused by adding a PTFE fluorine-containing anti-dripping agent into the halogen-free flame-retardant V0-grade PC material and 1.6 mm flame-retardant V0 does not reach the standard due to not adding the PTFE fluorine-containing anti-dripping agent can be solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of high molecular materials and its processing technology, and particularly relates to a fluorine-free and halogen-free flame-retardant polycarbonate composition and a preparation method thereof. BACKGROUND

[0002] Polycarbonate (PC) is an engineering plastic with excellent comprehensive performance, and has excellent transparency, high impact resistance and good heat resistance, and is widely used in electronic appliances, automobiles, aerospace and other fields. However, the limiting oxygen index (LOI) of PC is only 22-24%, and it is easy to produce melt drops during combustion, which can easily cause secondary fire. Now, the flame retardant performance of materials such as household appliance parts, automobile parts and 3C electronic products is generally required to reach V0 level (combustion time < 10s and no melt drop ignition) in vertical burning. In order to meet this stringent requirement, it is necessary to introduce a high-efficiency flame retardant system into PC materials, but the traditional technical path is still limited by the increasingly stringent environmental regulations.

[0003] Early flame-retardant PC materials mainly use halogen-containing flame retardants, such as bromine-based flame retardants. This kind of flame retardant will produce a large amount of toxic and harmful gases such as hydrogen bromide and hydrogen chloride during combustion, which will cause harm to the environment and human health. At present, halogen-free flame-retardant technology is widely used in the flame-retardant modification of PC materials. Compared with traditional halogen-containing flame retardants, halogen-free flame retardants do not release toxic and corrosive hydrogen halide gas during combustion, greatly reducing the harm to the human body and the environment when a fire occurs, and meeting the development trend of environmental protection and safety. However, halogen-free flame-retardant PC materials also face some challenges in practical application. On the one hand, the flame-retardant efficiency of halogen-free flame retardants is relatively low, and a higher addition amount is needed to achieve the ideal flame-retardant effect; on the other hand, halogen-free flame-retardant PC materials are prone to produce melt drops during combustion, which not only reduces the fire safety of the material, but also may cause further spread of the fire.

[0004] To solve the problem of melt dripping of halogen-free flame-retardant PC materials during combustion, the traditional method is to add polytetrafluoroethylene (PTFE) fluorine-containing anti-dripping agent. PTFE can effectively inhibit the dripping behavior of the material by changing the melt characteristics of the PC material during combustion, thereby improving the flame-retardant performance. For example, Chinese patent CN104403289A discloses a halogen-free flame-retardant PC material and a preparation method thereof, which uses benzene sulfonate silsesquioxane silicon flame retardant and organic PTFE anti-dripping agent to achieve thin-wall V0 flame-retardant effect. However, PTFE, which can effectively inhibit the generation of melt dripping, belongs to fluorine-containing materials and has potential risks of perfluoroalkyl and polyfluoroalkyl substances (PFAS) pollution. Since 2009, perfluorooctane sulfonic acid and its derivatives (PFOS) have been listed in the international Stockholm Convention, which regulates the elimination of global perfluorooctanoic acid (PFOA), its salts and PFOA-related compounds. The United States Environmental Protection Agency (EPA) has listed PFAS as a key pollutant and has developed relevant restriction standards. The European Union REACH regulation also strictly controls the use and discharge of PFAS. Therefore, non-fluorine anti-dripping agent has become the key to solving the melt dripping problem of halogen-free flame-retardant PC materials.

[0005] At present, although there are some halogen-free flame-retardant PC materials without fluorine, there are still some problems. For example, Chinese patent CN104403289A discloses a halogen-free flame-retardant PC plastic without fluorine and a preparation method thereof, which is composed of the following components by weight: 85-99.5 parts of PC resin; 0.1-7 parts of halogen-free flame retardant; 0.1-2 parts of non-fluorine anti-dripping agent; 0.1-0.3 parts of chain extender; 0.1-10 parts of other additives. However, the use of non-fluorine anti-dripping agent of surface-modified silicon nanotubes in melt blending has the risk of uneven dispersion and affects the performance stability. SUMMARY

[0006] The present application aims to solve the potential PFAS environmental protection risk caused by the addition of PTFE fluorine-containing anti-dripping agent in halogen-free flame-retardant V0 PC, and the problem of not meeting the 1.6mm flame-retardant V0 standard without adding PTFE anti-dripping agent, to provide a more environmentally friendly, safe and excellent performance PC material solution for electronic and electrical appliances, automobiles, aerospace and other fields, and to promote the development of PC materials towards a green and sustainable direction.

[0007] The present application aims to provide a non-fluorine halogen-free flame-retardant polycarbonate composition and a preparation method thereof, to solve the problem of potential PFAS environmental protection risk caused by the addition of PTFE fluorine-containing anti-dripping agent in halogen-free flame-retardant V0 PC and the problem of not meeting the 1.6mm flame-retardant V0 standard without adding PTFE anti-dripping agent.

[0008] To achieve the above-mentioned purpose, the present application realizes the following technical solutions:

[0009] A kind of fluorine-free halogen-free flame-retardant polycarbonate composition, the raw material composition according to the following weight parts: polycarbonate resin 70-90%; Halogen-free flame retardant 0.1-10%; Synergistic flame retardant 0-3%; Fumed silica 0-2%; Fluorine-free anti-dripping agent 0-6%; Auxiliary 0.1-2%.

[0010] The polycarbonate is selected from one or several of conventional polycarbonate, branched polycarbonate, siloxane polycarbonate.

[0011] The fluorine-free halogen-free flame retardant is one or several composite of organic silicon flame retardant, organic phosphate and phosphorus flame retardant.

[0012] The synergistic flame retardant is cage type polysiloxane, and its molecular structure formula is as follows:

[0013]

[0014] Wherein, R is the following structural formula:

[0015]

[0016] The fumed silica is an amorphous white powder, and the particle size is between 100-400 nm, and the specific surface area is between 150-400 m 2 / g.

[0017] The fluorine-free anti-dripping agent is a special modified organic silicon composite, carbonate silicate and melt-like reinforcing agent with high cross-linking structure.

[0018] The auxiliary includes one or more mixtures of hindered phenolic antioxidant, pentaerythritol stearate, silicone, magnesium stearate and calcium stearate.

[0019] The preparation method of the above-mentioned fluorine-free halogen-free flame-retardant polycarbonate composition comprises the following steps:

[0020] (1) the various raw materials after drying are weighed according to the formula proportion, and are stirred and mixed uniformly by high-speed stirrer, for standby;

[0021] (2) the above-mentioned mixed raw materials are added through the main feeding port of double-screw extruder, and are extruded, drawn, water-cooled and cut into particles at 250-290 DEG C to obtain the fluorine-free halogen-free flame-retardant polycarbonate composition.

[0022] Compared with the prior art, the present application has the following beneficial effects:

[0023] (1) the fluorine-free flame-retardant polycarbonate composition of the present application does not use fluorine-containing anti-dripping agent, avoids the PFAS environmental protection risk, meets the current requirements of environmental protection materials, and has good environmental friendliness.

[0024] (2) The fumed silica used in the present application can form a nano network structure, and the combination of the organic silicon flame retardant can weaken the dripping phenomenon and improve the flame retardant grade.

[0025] (3) The present application uses phosphazene flame retardant and cage type polysilsesquioxane synergistic flame retardant to integrate phosphorus, nitrogen and silicon three flame retardant factors. The phosphorus element combustion produces PO· group to capture free radicals to terminate combustion chain reaction, the nitrogen element can produce non-combustion gas to dilute oxygen to prevent combustion, and the silicon element has good carbonization effect to improve the stability of carbon layer.

[0026] (4) The melt enhancer with high cross-linking structure used in the present application can significantly improve the melt strength and prevent dripping, and realize the fluorine-free substitution of polycarbonate flame retardant.

[0027] (5) The present application meets the requirements of 1.6mm flame retardant V0 grade without fluorine and halogen, and does not affect the mechanical properties of polycarbonate material matrix. DETAILED DESCRIPTION

[0028] In order to make the purpose and technical scheme of the present application clearer and easier to understand, the present application will be further described in detail through specific examples, but the specific examples of the present application are only used to explain the present application and are not limited by the following implementation examples.

[0029] The examples and comparative examples of the present application relate to the following materials, but are not limited to the following materials:

[0030] Conventional polycarbonate resin, trade name PC-A1150, Wanhua Chemical;

[0031] Branched polycarbonate resin, trade name PC-WB2032, Wanhua Chemical;

[0032] Silicone polycarbonate resin, trade name PC-CH9115, Cangzhou Dahua;

[0033] Fumed silica, commercially available;

[0034] Flame retardant, phosphorus, commercially available;

[0035] Flame retardant, bisphenol A bis(diphenyl phosphate) BDP, trade name WSFR-BDP, Zhejiang Wansheng;

[0036] Flame retardant, silicone flame retardant, trade name FCA-107, Dow Corning;

[0037] Synergistic flame retardant, cage type polysilsesquioxane, trade name SI908, Guangsheng Polycarbonate Technology;

[0038] Anti-dripping agent, PTFE, trade name DB105, Suzhou Puleifei;

[0039] Fluorine-free anti-dripping agent, trade name SF99, Pan Plastic Technology Co., Ltd.

[0040] Auxiliary, silicone powder, commercially available; antioxidant 1010, commercially available; antioxidant 168, commercially available;

[0041] Preparation method of examples 1-4 and comparative examples 1-10:

[0042] (1) After drying, various raw materials were weighed according to the formula proportion, and were mixed uniformly by a high-speed stirrer, and were prepared for use;

[0043] (2) The above mixed raw materials were added through the main feeding port of the twin-screw extruder, and were extruded, drawn, water-cooled and pelletized at 250-290℃ to obtain the fluorine-free and halogen-free flame-retardant polycarbonate composition.

[0044] Preparation of flame-retardant polycarbonate composition test bars:

[0045] After drying the above materials in a forced air drying oven at 120℃ for 4h, standard bars were injection molded at an injection molding temperature of 260-290℃. After the mechanical property bars were injection molded, they were conditioned in a laboratory standard environment (23℃, 50% RH) for 24h before testing.

[0046] Test method of each performance index:

[0047] Tensile properties: according to ISO 527 method, bar size: 170*10*4mm 3 , test speed 5mm / min.

[0048] Bending properties: according to ISO 178 method, bar size: 80*10*4mm 3 , test speed 2mm / min.

[0049] Notched impact properties: according to ISO 179 method, bar size: 80*10*4mm 3 .

[0050] Flame-retardant properties: according to UL94 method, bar size: 127*12.7*1.6mm 3 .

[0051] Table 1: Composition and properties of flame-retardant polycarbonate compositions of examples 1-4 and comparative examples 1-10

[0052]

[0053] From the results of the above Table 1 examples and comparative examples, it can be seen that, at the same amount of flame retardant additive, the higher the amount of SF99 anti-dripping agent, the better the flame retardant effect (Example 1, Comparative Examples 1-4). Replacing BDP with phosphine flame retardant and compounding with synergistic flame retardant can reduce the amount of SF99, and the flame retardant efficiency is significantly improved (Example 2, Comparative Examples 5-6). Subsequently, a certain amount of fumed silica is added, and with the increase of the amount of fumed silica, the amount of phosphine flame retardant and polysiloxane synergistic flame retardant is further reduced, which is mainly due to the formation of nanometer network structure, which can effectively improve the flame retardant grade (Example 3, Comparative Examples 7-8). Further, by comparing different types of polycarbonate matrix, the use of branched polycarbonate can further reduce the amount of SF99, which is mainly due to the special branched structure which can hinder the melt dripping (Example 4, Comparative Examples 9-10). In summary, the polycarbonate composition prepared by the present application can effectively control the melt dripping phenomenon of polycarbonate during combustion, and the effect can replace the use of PTFE anti-dripping agent, achieve 1.6mm thickness V0 flame retardant, while maintaining excellent mechanical properties, which is very suitable for application in the fields of automobile industry, new energy battery, electronic and electrical appliances and aerospace, etc.

Claims

1. A fluorine-free, halogen-free, flame-retardant polycarbonate composition characterized in that: The raw material composition is as follows in weight fraction: polycarbonate resin 70-90%; halogen-free flame retardant 0.1-10%; synergistic flame retardant 0-3%; fumed silica 0-2%; fluorine-free anti-dripping agent 0-6%; auxiliary agent 0.1-2%.

2. A fluorine-free, halogen-free, flame-retardant polycarbonate composition according to claim 1, characterized in that: The polycarbonate is selected from one or several of conventional polycarbonate, branched polycarbonate and siloxane polycarbonate.

3. A fluorine-free, halogen-free, flame-retardant polycarbonate composition according to claim 1, characterized in that: The fluorine-free halogen-free flame retardant is one or several of organic silicon flame retardant, organic phosphate and phosphorus flame retardant.

4. A fluorine-free, halogen-free, flame-retardant polycarbonate composition according to claim 1, characterized in that: The synergistic flame retardant is cage-type polysiloxane, and its molecular structure is as follows: In which, R is as follows:

5. A fluorine-free, halogen-free, flame-retardant polycarbonate composition according to claim 1, characterized in that: The fumed silica is an amorphous white powder having a particle size of 100-400 nm and a specific surface area of 150-400 m 2 / g.

6. A fluorine-free, halogen-free, flame-retardant polycarbonate composition according to claim 1, characterized in that: The fluorine-free anti-dripping agent is special modified organic silicon compound, carbonate silicate and melt-like reinforcing agent SF99 with high cross-linking structure.

7. A fluorine-free, halogen-free, flame-retardant polycarbonate composition according to claim 1, characterized in that: The auxiliary agent includes one or more of hindered phenol antioxidant, pentaerythritol stearate, silicone, magnesium stearate and calcium stearate.

8. A process for the preparation of the flame retardant fluorine- and halogen-free polycarbonate composition according to any one of claims 1 to 7, characterized in that, The method comprises the following steps: (1) the dry raw materials are weighed according to the formula proportion, and are stirred and mixed uniformly through a high-speed stirrer for standby; (2) the mixed raw materials are added through the main feeding port of a double-screw extruder, are extruded through plasticization at 250-290℃, are drawn, are water-cooled, and are cut into particles to obtain the fluorine-free halogen-free flame-retardant polycarbonate composition.

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