A fluorine-free transparent flame-retardant polycarbonate composition and a method for preparing the same

Abstract

The application discloses a kind of fluorine-free transparent flame-retardant polycarbonate compositions and preparation method thereof, by the following components are made of by weight parts: high viscosity polycarbonate 20-80 weight parts, silicon copolymer polycarbonate 20-70 weight parts, fluorine-free compound flame retardant 1-10 weight parts, phosphate modified phenyl silicone resin 0.5-3 weight parts, acrylate core-shell toughening agent 1-6 weight parts, antioxidant 0.1-0.5 weight parts, lubricant 0.1-0.5 weight parts.The application introduces KSS / HPCTP / POSS ternary fluorine-free synergistic flame-retardant system and the synergistic effect of appropriate phosphate modified phenyl silicone resin and MBS toughening agent, improves the flame-retardant efficiency under the premise of maintaining the light transmittance and mechanical properties.The method proposed by the application effectively solves the problem of non-compliance of flame-retardant dripping caused by lack of PTFE in the existing halogen-free flame-retardant PC system, while avoiding the PFAS environmental risk.

Description

Technical Field

[0001] This invention relates to the field of polymer materials and their processing technology, and in particular to a fluorine-free transparent flame-retardant polycarbonate composition and its preparation method. Technical Background

[0002] Polycarbonate (PC) is a thermoplastic engineering plastic with excellent comprehensive performance. Its molecular backbone contains carbonate groups, and it is one of the five major general-purpose engineering plastics. PC material possesses excellent light transmittance (87%~93% at a thickness of 3 mm), extremely high impact strength, good dimensional stability, excellent electrical insulation properties, and a wide operating temperature range (-60℃~120℃). It is widely used in electronics, automotive, medical devices, building materials, optical components, and aerospace. However, while its inherent flame retardant properties (V2 rating) are superior to most general-purpose plastics, they still cannot meet the stringent requirements of many high-tech applications. Especially in consumer electronics, new energy vehicles, high-end optical components, and 5G communication equipment, its flame retardant standard must reach a UL 94 V-0 rating at a thickness of 1.6 mm.

[0003] Improving the flame retardant properties of PC can be achieved by adding various flame retardants. However, most conventional flame retardants have poor compatibility with the PC matrix, and after addition, they form a microscopic dispersed phase in the PC matrix, causing incident light to scatter and refract at the interface, resulting in a significant decrease in light transmittance and an increase in haze. Currently, flame retardant systems suitable for transparent PC mainly include halogen-free flame retardants such as sulfonate-based, organosilicon-based, and organophosphorus-based flame retardants.

[0004] In recent years, global environmental regulations on fluorinated compounds have become increasingly stringent. This is especially true for fluorinated additives in PC flame retardant systems, such as PFBS (perfluorobutyl sulfonate) and PTFE (polytetrafluoroethylene), which are widely used. With the continuous introduction and strengthening of PFAS restrictions in Europe and the United States, the industry's demand for fluorine-free flame retardant solutions is becoming increasingly urgent. Traditional fluorinated additives face increasing environmental compliance pressures, making the development of transparent flame-retardant PC material systems that do not rely on fluorinated compounds a pressing need and a key research direction in the field of PC modification.

[0005] This invention aims to develop a polycarbonate material that combines excellent transparency and high-efficiency flame retardant properties (UL 94 V-0 rating) and is completely free of fluorine-based flame retardant additives (including PFBS, PTFE, etc.). This material has significant technical value and market significance for meeting flame retardant safety standards, responding to the global PFAS environmental regulatory trend, and expanding the application of PC in fields such as electronics, automotive, medical devices, building materials, optical devices, and aerospace. Summary of the Invention

[0006] The purpose of this invention is to provide a fluorine-free transparent flame-retardant polycarbonate composition and its preparation method, which achieves a UL94 V0 flame retardant rating of 1.6 mm thickness without using any fluorine-containing flame retardants or anti-dripping agents, while also possessing excellent transparency.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] In a first aspect, the present invention provides a fluorine-free transparent flame-retardant polycarbonate composition, comprising raw materials in the following parts by weight:

[0009] 20-80 parts of high-viscosity polycarbonate resin;

[0010] 20-70 parts of silicon-co-polycarbonate;

[0011] 1-10 parts of fluorine-free compound flame retardant;

[0012] 0.5-3 parts of phosphate-modified phenyl silicone resin;

[0013] 1-6 parts of acrylate core-shell toughening agent;

[0014] Antioxidant 0.1-0.5 parts;

[0015] Lubricant 0.1-0.5 parts;

[0016] The fluorine-free compound flame retardant is composed of sulfonate flame retardant, hexaphenoxycyclotriphosphazene (HPCTP) and organic silsesquioxane (such as cage-type polysilsesquioxane, POSS) in a mass ratio of (0.5-2):(1-8):(0.5-2.5).

[0017] Preferably, the silicon copolymer polycarbonate has a melt flow rate of 5-20 g / 10 min at 300℃ / 1.2 kg, and the content of organosiloxane segments is 2-10 wt%. PC-CH9115 (Cangzhou Dahua) is available for purchase.

[0018] Preferably, the high-viscosity polycarbonate has a melt flow rate of 2-4 g / 10 min at 300℃ / 1.2 kg. PC-WB2032 (Wanhua Chemical) is available for purchase.

[0019] Preferably, the phosphate-modified phenyl silicone resin is prepared by the following method:

[0020] (1) Dissolve hydroxyphenyl silicone resin and phosphate ester by stirring at 90°C;

[0021] (2) Add dibutyltin dilaurate (DBTDL) to the above solution, heat to 130℃, react for 8 hours, and stop the reaction when the acid value is <5mgKOH / g;

[0022] (3) Remove byproducts such as ethanol / phenol by vacuum distillation and filter to obtain phosphate-modified phenyl silicone resin.

[0023] Preferably, the acrylate core-shell toughening agent is a methyl methacrylate-butadiene-styrene copolymer, with a core layer of butadiene-styrene rubber and a shell layer of methyl methacrylate polymer.

[0024] Preferably, the sulfonate flame retardant is potassium benzenesulfonylbenzenesulfonate, and the organic silsesquioxane is a cage-type silsesquioxane (POSS).

[0025] Secondly, the present invention provides a method for preparing the above-mentioned fluorine-free transparent flame-retardant polycarbonate composition, comprising the following steps:

[0026] (1) Weigh the dried silicone copolymer polycarbonate, high viscosity polycarbonate, fluorine-free compound flame retardant, phosphate ester modified phenyl silicone resin, acrylate core-shell toughening agent, antioxidant and lubricant according to the ratio, and mix them evenly in a high-speed mixer.

[0027] (2) The uniformly mixed material is added to a twin-screw extruder, and after plasticizing extrusion, stretching, water cooling and pelletizing, the fluorine-free transparent flame-retardant polycarbonate composition is obtained. The processing temperature of the extruder is 240-280℃ and the screw speed is 200-400 rpm.

[0028] Preferably, in step (1), the drying conditions for the silicon copolymer polycarbonate and high viscosity polycarbonate are: drying at 100-120°C for 4-6 hours.

[0029] Preferably, in step (2), the length-to-diameter ratio of the twin-screw extruder is 35:1 to 45:1.

[0030] Thirdly, the present invention provides the application of the above-described fluorine-free transparent flame-retardant polycarbonate composition in the housings of electronic appliances, automobiles, aviation or lighting equipment.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The fluorine-free transparent flame-retardant polycarbonate composition of the present invention does not use fluorine-containing anti-dripping agents, avoids the environmental risks of PFAS, meets the current requirements for environmentally friendly materials, and has good environmental friendliness.

[0033] (2) The phosphorus-silicon-sulfonate synergistic system used in this invention has high flame retardant efficiency and can reach UL94 V0 level with a thickness of 1.6 mm without dripping.

[0034] (3) By selecting additives that match the refractive index of PC and controlling the introduction of opaque fillers, the present invention produces a material with high light transmittance and low haze.

[0035] (4) The present invention does not affect the mechanical properties of the polycarbonate material matrix while meeting the 1.6 mm flame retardant V0 grade fluorine-free transparent flame retardant requirement. Detailed Implementation

[0036] To make the objectives and technical solutions of this invention clearer and easier to understand, the invention will be further described in detail below through specific embodiments. However, the specific embodiments of this invention are only used to explain the invention, and the scope of protection of this invention is not limited to the following embodiments.

[0037] The embodiments and comparative examples of the present invention relate to, but are not limited to, the following materials:

[0038] High viscosity polycarbonate resin, trade name PC-WB2032, Wanhua Chemical;

[0039] Silicon copolymer polycarbonate resin, trade name PC-CH9115, Cangzhou Dahua;

[0040] Conventional polycarbonate resin, trade name PC-A1100, Wanhua Chemical;

[0041] Hexaphenoxycyclotriphosphazene (HPCTP), commercially available;

[0042] Cage-type polysilsesquioxane, trade name SI908, Quansheng Polycarbon Technology;

[0043] Potassium benzenesulfonylbenzenesulfonate (KSS), trade name F535, manufactured by Arichem, USA;

[0044] Acrylic core-shell toughening agent MBS, trade name M701, Kanekachi Chemical, Japan;

[0045] Antioxidants, a combination of hindered phenols (Irganox 1076) and phosphites (Irgafos 168), in a mass ratio of 1:1;

[0046] Lubricant, pentaerythritol stearate (PETS), commercially available;

[0047] Phosphate ester modified phenyl silicone resin, prepared in-house, is prepared as follows:

[0048] (1) Hydroxyphenyl silicone resin (purchased from Shuaiyan Ligao Biomedicine) and phosphate ester were stirred and dissolved at 90°C;

[0049] (2) Add dibutyltin dilaurate (DBTDL) to the above solution, heat to 130℃, react for 8 hours, and stop the reaction when the acid value is <5mgKOH / g;

[0050] (3) Remove byproducts such as ethanol / phenol by vacuum distillation and filter to obtain phosphate-modified phenyl silicone resin.

[0051] The formulations of Examples 1-4 and Comparative Examples 1-8 are shown in Table 1, and the preparation methods are as follows:

[0052] (1) Weigh out the dried raw materials and additives according to the formula ratio, and mix them evenly with a high-speed mixer for later use;

[0053] (2) The above mixed raw materials are added through the main feed port of a twin-screw extruder, and after plasticizing extrusion, stretching, water cooling and pelletizing at 240-280℃ and screw speed of 200-400 rpm, a fluorine-free transparent flame-retardant polycarbonate composition is obtained.

[0054] The compositions prepared in Examples 1-4 and Comparative Examples 1-8 were subjected to performance tests. The test strips for the flame-retardant polycarbonate compositions were prepared as follows:

[0055] The above materials were dried in a forced-air drying oven at 120 ℃ for 4 h, and then injection molded into standard specimens at an injection molding temperature of 260-290 ℃. The injection-molded mechanical property specimens were then conditioned in a standard laboratory environment (23 ℃, 50% RH) for 24 h before testing.

[0056] The testing methods for each performance indicator are as follows:

[0057] Tensile properties: According to ISO 527 method, specimen dimensions: 170*10*4 mm 3 The test speed was 5 mm / min.

[0058] Bending performance: According to ISO 178 method, spline dimensions: 80*10*4 mm 3 The test speed was 2 mm / min.

[0059] Notched impact performance: according to ISO 179 method, spline size: 80*10*4 mm 3 .

[0060] Transmittance / haze: ASTM D1003, sample thickness 3.0 mm.

[0061] Flame retardant performance: According to UL94 method, sample size: 127*12.7*1.6 mm 3 .

[0062] Table 1: Composition (parts by weight) and properties of flame-retardant polycarbonate compositions of Examples 1-4 and Comparative Examples 1-8

[0063]

[0064] As can be seen from the test results of the examples and comparative examples in Table 1 above, KSS, HPCTP, and POSS must be used in combination to achieve V-0 grade non-dripping flame retardancy (Example 1, Comparative Examples 1-4). Replacing high-viscosity PC (WB2032) with conventional PC (A1100) reduced the flame retardancy grade to V2, with severe dripping, indicating that the high molecular weight and branched structure of high-viscosity PC play an important role in improving melt strength and inhibiting dripping (Example 1, Comparative Example 5). Adding an appropriate amount of phosphate ester modified phenyl silicone resin not only helps with anti-dripping but also improves transparency and mechanical properties (Example 1, Comparative Examples 6-8). The fluorine-free transparent flame-retardant polycarbonate compositions prepared in Examples 1-4 all achieved a UL94 V0 flame retardant rating at a thickness of 1.6 mm. As the content of silicon copolymer PC increased from 45 parts to 65 parts, and the total amount of fluorine-free compounded flame retardant increased from 3 parts to 5.4 parts, the flame retardant performance of the material gradually improved. Simultaneously, the notched impact strength first decreased and then increased (the silicon copolymer PC content was highest in Example 4, with an impact strength of 66.3 kJ / m²), demonstrating the improving effect of silicon copolymer PC on low-temperature toughness. In summary, the fluorine-free transparent flame-retardant polycarbonate composition proposed in this invention, through the matrix compounding of high-viscosity PC and silicon copolymer PC, the synergistic effect of the KSS / HPCTP / POSS ternary fluorine-free synergistic flame retardant system, and the synergistic effect of appropriate amounts of phosphate ester modified phenyl silicone resin and MBS toughening agent, successfully achieved a UL94 V0 flame retardant rating, light transmittance ≥85%, and excellent mechanical properties at a thickness of 1.6 mm without using any fluorine-containing additives (including PFBS flame retardants and PTFE anti-dripping agents). This technical solution effectively solves the problem of substandard flame retardant dripping caused by the lack of PTFE in existing halogen-free flame retardant PC systems, while avoiding the environmental risks of PFAS.

Claims

1. A fluorine-free, transparent, flame-retardant polycarbonate composition, characterized in that, It consists of the following raw materials in parts by weight: 20-80 parts of high-viscosity polycarbonate; 20-70 parts of silicon-co-polycarbonate; 1-10 parts of fluorine-free compound flame retardant; 0.5-3 parts of phosphate-modified phenyl silicone resin; 1-6 parts of acrylate core-shell toughening agent; Antioxidant 0.1-0.5 parts; Lubricant 0.1-0.5 parts; The fluorine-free compound flame retardant is composed of sulfonate flame retardant, hexaphenoxycyclotriphosphazene and organic silsesquioxane in a mass ratio of (0.5-2):(1-8):(0.5-2.5).

2. The fluorine-free transparent flame-retardant polycarbonate composition according to claim 1, characterized in that: The silicon copolymer polycarbonate has a melt flow rate of 5-20 g / 10 min at 300℃ / 1.2 kg, wherein the content of organosiloxane segments is 2-10 wt%.

3. The fluorine-free transparent flame-retardant polycarbonate composition according to claim 1, characterized in that: The high-viscosity polycarbonate has a melt flow rate of 2-4 g / 10min at 300℃ / 1.2kg.

4. The fluorine-free transparent flame-retardant polycarbonate composition according to claim 1, characterized in that: The phosphate-modified phenyl silicone resin is prepared by the following method: (1) Dissolve hydroxyphenyl silicone resin and phosphate ester by stirring at 90°C; (2) Add dibutyltin dilaurate to the above solution, heat to 130℃, react for 8 hours, and stop the reaction when the acid value is < 5mg KOH / g; (3) Remove byproducts by vacuum distillation and filter to obtain phosphate-modified phenyl silicone resin.

5. The fluorine-free transparent flame-retardant polycarbonate composition according to claim 1, characterized in that: The acrylate core-shell toughening agent is a methyl methacrylate-butadiene-styrene copolymer, with a core layer of butadiene-styrene rubber and a shell layer of methyl methacrylate polymer.

6. The fluorine-free transparent flame-retardant polycarbonate composition according to claim 1, characterized in that: The sulfonate flame retardant is potassium benzenesulfonylbenzenesulfonate, and the organic silsesquioxane is a cage-type silsesquioxane.

7. A method for preparing the fluorine-free transparent flame-retardant polycarbonate composition according to any one of claims 1-6, characterized in that, Includes the following steps: (1) Weigh the dried silicone copolymer polycarbonate, high viscosity polycarbonate, fluorine-free compound flame retardant, phosphate ester modified phenyl silicone resin, acrylate core-shell toughening agent, antioxidant and lubricant according to the ratio, and mix them evenly in a high-speed mixer; (2) The uniformly mixed material is added to a twin-screw extruder, and after plasticizing extrusion, stretching, water cooling and pelletizing, the fluorine-free transparent flame-retardant polycarbonate composition is obtained. The processing temperature of the extruder is 240-280℃ and the screw speed is 200-400 rpm.

8. The preparation method according to claim 7, characterized in that, In step (1), the drying conditions for the silicon copolymer polycarbonate and high viscosity polycarbonate are: drying at 100-120℃ for 4-6 hours.

9. The preparation method according to claim 7, characterized in that, In step (2), the length-to-diameter ratio of the twin-screw extruder is 35:1 to 45:

1.

10. The use of the fluorine-free transparent flame-retardant polycarbonate composition according to any one of claims 1-6 in the housings of electronic appliances, automobiles, aviation or lighting equipment.

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