Flame-retardant PC resin composition meeting thin-wall S.2 needle flame standard as well as preparation method and application of flame-retardant PC resin composition

Abstract

The invention relates to a flame-retardant PC resin composition meeting a thin-wall S.2 needle flame standard as well as a preparation method and application thereof. The flame-retardant PC resin composition comprises the following components in parts by weight: 92-98 parts of PC resin, 0.1-1 part of a sulfonate flame retardant, 0.1-1 part of a toughening agent, 1-3 parts of phosphate, 0.5-2 parts of a boron-containing compound, 0.5-2 parts of fumed silica and 0.5-1 part of an auxiliary agent. The preparation method comprises the following steps: stirring and fully mixing the raw materials in a high-speed mixer, conveying, shearing and mixing by a double-screw extruder through screws, and melting, homogenizing, drawing, cooling and pelletizing the materials to obtain the flame-retardant PC resin composition meeting the thin-wall S.2 needle flame standard. Compared with the prior art, the composite material not only has stable flame retardant property, meets the thin-wall S.2 needle flame standard, but also has relatively excellent mechanical property and thermal stability, is relatively low in cost, and is very suitable for being applied to the fields of power adapters, OAs, new energy batteries, electronics and electrics, electric control boxes, switches and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a flame-retardant PC resin composition meeting the thin-wall S.2 needle flame standard, and a preparation method and application thereof. Background Art

[0002] Ultra-thin, aesthetically pleasing designs are becoming a dominant trend in current product design. From mobile phones and wearables to audio and communications equipment, printers, and even large and small appliances, all products are striving for an extremely slim appearance. However, this fashion trend also poses unprecedented challenges to the flame retardancy of materials. Materials that previously only met V0 flame retardancy standards now pose significant safety risks under today's more stringent new standards.

[0003] Against this backdrop, the needle flame test S2 standard GB / T4943.1-2022 was developed, significantly strengthening the requirements for burn-through resistance of plastic components. While PC (polycarbonate) resin exhibits excellent flame retardancy, achieving UL V-2 flame retardancy and boasting a high limiting oxygen index of 21%-24%, its burn-through resistance still needs improvement. This is particularly true for thin-walled components with thicknesses below 1.5mm, which are prone to burn-through and struggle to pass the 60-second S2 needle flame test.

[0004] Currently, to ensure PC resins meet the S2 needle flame standard, a common approach is to improve PC's charring ability to enhance burn-through resistance. For example, silicone flame retardant systems such as silicone copolymer PC, phenyl silicone, and POSS are used. However, these systems significantly increase modification costs. Alternatively, fillers with synergistic flame retardant properties, such as talc, nano-montmorillonite, and wollastonite, can achieve a certain degree of stable flame retardancy. However, these systems suffer from low impact strength, impacting the performance of end products and often only meeting the S2 needle flame standard for wall thicknesses of 1.5mm or greater.

[0005] Chinese patent CN118006105A discloses a needle flame resistant polycarbonate composition composed of 89.8% to 99.5% polycarbonate resin, 0.1% to 9% epoxy resin, 0.1% to 1% aromatic polyamine, and 0.1% to 1% sulfonate flame retardant. The polymer can pass the S.2 needle flame test in 5169.5-2020 at a wall thickness of 0.6 mm. It does not require the addition of a large amount of flame retardant to achieve a V0 flame retardancy and can also meet the safety requirements of the new national standard GB 4943.1-2022. In addition, due to the lack of the addition of a large amount of flame retardant, excellent mechanical properties are retained. Although the invention can meet the national standard S.2 needle flame 60s standard, the maximum burn-through time margin of its embodiments is not sufficient, and the burn-through time is all below 80s, which has the risk of burn-through failure. Moreover, the patent adds alkaline aromatic polyamines. As we all know, PC is extremely sensitive to alkaline substances, which means that there are certain risks in the hydrolysis resistance and thermal stability of the resin composition. Summary of the Invention

[0006] The purpose of the present invention is to provide a flame-retardant PC resin composition that meets the thin-wall S.2 needle flame standard, as well as its preparation method and application. The flame-retardant PC resin composition has excellent burn-through resistance, can meet the S.2 needle flame standard for wall thicknesses of 1.5 mm and below, can achieve V-0 grade flame retardancy, and has low cost, while also having excellent mechanical properties and thermal stability.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] One of the objects of the present invention is to provide a flame retardant PC resin composition that meets the thin-wall S.2 needle flame standard, comprising the following components in parts by weight:

[0009]

[0010] Preferably, the PC resin has a melt index of 6-20 g / 10 min at 300° C. and a load of 1.2 kg.

[0011] Preferably, the sulfonate flame retardant is selected from any one or two of potassium perfluorobutanesulfonate, potassium diphenylsulfone-3-sulfonate, and aromatic sulfonate HES.

[0012] Preferably, the toughening agent is a silicon-containing acrylate core-shell toughening agent.

[0013] Further preferably, in the silicon-containing acrylate core-shell toughening agent, the silicone acrylate rubber serves as the core, and its content is 50 wt%-65 wt%.

[0014] More preferably, the particle size of the silicon-containing acrylic core-shell toughening agent is 150 nm-300 nm.

[0015] Further preferably, the silicon content of the silicon-containing acrylic core-shell toughening agent is 30 wt%-70 wt%.

[0016] Further preferably, the shell of the silicon-containing acrylic core-shell toughening agent is polymethyl methacrylate (PMMA).

[0017] Preferably, the phosphate is selected from any one of zinc phosphate, zirconium phosphate, barium phosphate, barium hypophosphite, barium metaphosphate, aluminum hypophosphite, zinc hypophosphite, sodium phosphate, and sodium hypophosphite, and the particle size of the phosphate is 2um-8um.

[0018] In the present invention, if the particle size of the phosphate is less than 2 μm, it is easy to be unevenly dispersed, affecting the flame retardant performance; if the particle size is greater than 8 μm, the impact performance of the flame retardant PC resin composition will be sharply deteriorated.

[0019] Preferably, the boron-containing compound is selected from any one of zinc borate, boron oxide, and boric acid.

[0020] Preferably, the particle size of the fumed silica is 150nm-350nm, and the specific surface area is 150-400m 2 / g.

[0021] Preferably, the auxiliary agent is selected from one or more of silane coupling agent, titanate coupling agent, hindered phenol antioxidant, phosphite antioxidant, ethylene bisstearamide, polyethylene wax, pentaerythritol stearate, magnesium stearate, calcium stearate, and benzotriazole UV absorber.

[0022] A second object of the present invention is to provide a method for preparing a flame-retardant PC resin composition that meets the thin-wall S.2 needle flame standard, which specifically comprises the following steps:

[0023] S1. Weigh each component by weight and mix them evenly to obtain a mixed raw material;

[0024] S2. The mixed raw materials obtained in step S1 are sheared and mixed by a twin-screw extruder. The mixed raw materials are melted, homogenized, drawn into strips, cooled, and pelletized to obtain the flame-retardant PC resin composition meeting the thin-wall S.2 needle flame standard.

[0025] Preferably, the screw length-diameter ratio of the twin-screw extruder is (35-50):1, the screw speed is 300-500 rpm, and the extrusion temperature is 260-280°C.

[0026] Further preferably, the screw length-to-diameter ratio of the twin-screw extruder is 40:1.

[0027] Further preferably, the screw speed is 400 rpm.

[0028] Further preferably, the twin-screw extruder is equipped with a temperature control device and a vacuum pumping device.

[0029] Further preferably, the method for preparing the flame-retardant PC resin composition that meets the thin-wall S.2 needle flame standard specifically comprises the following steps: PC resin, sulfonate flame retardant, toughening agent, phosphate, boron-containing compound, fumed silica and additives are stirred and fully mixed in a high-speed mixer, and then fed into a twin-screw extruder through a metering device; under the conveying, shearing and mixing of the screws, the materials are melted, homogenized, drawn into strands, cooled, and pelletized to obtain a flame-retardant PC resin composition that meets the thin-wall S.2 needle flame standard;

[0030] The twin-screw extruder has a screw length-to-diameter ratio of 40 and is equipped with a temperature control device and a vacuum device. The extrusion temperature of the twin-screw extruder is 260-280°C and the screw speed is 400 rpm.

[0031] The third object of the present invention is to provide an application of the flame-retardant PC resin composition that meets the thin-wall S.2 needle flame standard in the fields of power adapters, new energy batteries, office equipment, electronic and electrical equipment, electric control boxes, and switches.

[0032] In the existing technology, silicone flame retardant systems are often used to improve the carbonization ability of PC and fillers with flame retardant synergistic effects are used to stabilize the flame retardant effect. However, the former will increase the cost dramatically, and the latter has low impact strength, which is not conducive to terminal use.

[0033] The present invention introduces a synergistic ternary system of phosphate, boron-containing compound, and fumed silica into a PC resin composition, thereby providing a flame-retardant PC resin composition that meets the S.2 needle flame standard for thin-walled products. In this flame-retardant PC resin composition, the fumed silica forms a continuous nano-network structure within the PC melt, improving melt strength and effectively preventing sagging and dripping during combustion. The boron-containing compound lowers the silica sintering temperature, enhancing the porcelain-forming effect and forming a dense ceramic structure during combustion. Finally, the flame-retardant and highly charred phosphate further enhances the strength of the char layer during combustion, improving the thin-walled product's burn resistance. This allows the flame-retardant PC resin composition prepared by the present invention to ultimately pass the S.2 needle flame test.

[0034] Compared to existing technologies, the present invention utilizes the synergistic effects of low-temperature porcelain formation and condensed-phase flame retardancy as described above to reduce the amount of corresponding flame-retardant charring components added, significantly improving the density and strength of the char layer and significantly enhancing the burn-through resistance of the PC resin. This enables the production of a flame-retardant PC resin composition that meets the thin-wall S.2 needle flame standard at a low cost and offers excellent mechanical properties. Furthermore, the burn-through resistance time in the national standard S.2 needle flame test exceeds 100 seconds, even reaching the limit combustion time of 300 seconds.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) The present invention provides a flame-retardant PC resin composition, comprising a PC resin, a sulfonate flame retardant, a toughening agent, a phosphate, a boron-containing compound, fumed silica, and an additive. The acid salt-boron-containing compound-fumed silica ternary compound system has a synergistic effect, which enables the flame-retardant PC resin composition of the present invention to meet the S.2 needle flame standard for thin-walled products with a wall thickness of 1.5 mm or less, achieve V-0 grade flame retardancy, and also have excellent burn-through resistance, mechanical properties, thermal stability, and low cost.

[0037] (2) The present invention uses fumed silica to form a continuous nano-network structure in the PC melt to improve the melt strength, then uses a boron-containing compound to reduce the sintering temperature of silica into porcelain and enhance the density of the ceramic structure. Finally, a phosphate that is both flame retardant and highly charred is used to further enhance the strength of the carbon layer during the combustion process and improve the thin-walled burning resistance, so that the prepared flame-retardant PC resin composition can pass the S.2 needle flame standard test.

[0038] (3) The present invention reduces the addition amount of the corresponding flame retardant carbonizing components through the synergistic effect of low-temperature porcelain formation and condensed phase flame retardancy, greatly improves the density and strength of the carbon layer, significantly enhances the burn-through resistance of PC resin, reduces the modification cost of S.2 needle flame flame retardant PC, and at the same time has excellent mechanical properties.

[0039] (4) The flame-retardant PC resin composition prepared by the present invention can pass the S.2 needle flame standard limit combustion 300s test under the thin-wall condition of 1.2mm wall thickness, has excellent burn-through resistance, and the flame retardant grade reaches V-0 grade. At the same time, the impact strength can reach 57KJ / m 2 , tensile strength reaches 58MPa, and comprehensive performance is excellent.

[0040] (5) Since the component ratio of the present invention does not contain alkaline substances, the flame-retardant PC resin composition prepared by the present invention has excellent burn-through resistance and good thermal stability, and no silver wire is generated during the injection molding process.

[0041] (6) The flame-retardant PC resin composition prepared by the present invention that meets the S.2 needle flame standard for thin-walled products with a wall thickness of 1.5 mm or less meets the current product design concept and is suitable for various fields such as power adapters, new energy batteries, office equipment, electronic and electrical equipment, electric control boxes, switches, etc. DETAILED DESCRIPTION

[0042] The following is a detailed description of an embodiment of the present invention. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process. However, the protection scope of the present invention is not limited to the following embodiment.

[0043] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present invention are conventional reagents, methods, instruments and equipment in the art. Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0044] The raw materials used in the following examples and comparative examples are:

[0045] PC resin, S-2000F, Mitsubishi Chemical, melt index 12g / 10min;

[0046] Sulfonate flame retardant, KSS, Arichem, USA;

[0047] Sulfonate flame retardant, FR2025, 3M, USA;

[0048] Toughening agent, MR01, Kaneka Chemical, Japan;

[0049] Barium phosphate, Nanjing Chemical Reagent;

[0050] Zirconium phosphate-1, Fujian Ruisen, particle size less than 2um;

[0051] Zirconium phosphate-2, Fujian Ruisen, particle size 10 μm;

[0052] Boron trioxide, Liaoning Boronda Technology;

[0053] Zinc borate, HT207, Jinan Taixing;

[0054] Fumed silica, M-5, Cabot, specific surface area 200 m2 / g;

[0055] Talc, 3CA, Yirui stone;

[0056] Silicone flame retardant, OPCTS, Shin-Etsu, Japan;

[0057] Antioxidant, BASF, Irganox S9228;

[0058] Anti-drip agent, SN3300B3, Guangzhou Entropy

[0059] Lubricant, Italian hair base, PETS.

[0060] Example

[0061] The proportions of the following examples are shown in Table 1, wherein:

[0062] Examples 1-5

[0063] PC resin, sulfonate flame retardant, toughening agent, phosphate, boron-containing compound, fumed silica and additives were weighed according to the ratio in Table 1, stirred and mixed thoroughly in a high-speed mixer, and then fed into a twin-screw extruder through a metering device. Under the conveying, shearing and mixing of the screws, the materials were melted, homogenized, drawn into strips, cooled and pelletized to obtain a flame-retardant PC resin composition that met the thin-wall S.2 needle flame standard.

[0064] The twin-screw extruder has a screw length-to-diameter ratio of 40 and is equipped with a temperature control device and a vacuum device. The extrusion temperature of the twin-screw extruder is 260-280°C and the screw speed is 400 rpm.

[0065] Comparative Example

[0066] The following comparative examples are given in Table 1-2, where:

[0067] Comparative Example 1

[0068] Comparative Example 1 does not contain phosphate, boron-containing compound, or fumed silica, but uses organic silicon instead. The preparation method is the same as that of Examples 1-5.

[0069] Comparative Example 2

[0070] Comparative Example 2 does not contain phosphate, boron-containing compounds, and fumed silica, but uses talc instead. The preparation method is the same as that of Comparative Example 1.

[0071] Comparative Example 3

[0072] In this comparative example 3, based on comparative example 2, the toughening agent content is increased, and the preparation method is the same as comparative example 2.

[0073] Comparative Example 4

[0074] In this comparative example 4, based on Example 5, no boron-containing compound is included, and the preparation method is the same as that of Example 5.

[0075] Comparative Example 5

[0076] In this comparative example 5, based on Example 5, phosphate is not contained and the preparation method is the same as that of Example 5.

[0077] Comparative Example 6

[0078] In this comparative example 6, based on Example 5, fumed silica is not included and the preparation method is the same as that of Example 5.

[0079] Comparative Example 7

[0080] In this comparative example 7, based on Example 5, the phosphate content was reduced and the preparation method was the same as that of Example 5.

[0081] Comparative Example 8

[0082] In this comparative example 8, based on Example 5, no toughening agent is included and the preparation method is the same as that of Example 5.

[0083] Comparative Example 9

[0084] In this comparative example, based on Example 2, phosphate with a particle size of 10 μm was used, and the preparation method was the same as that of Example 2.

[0085] The PC resin compositions prepared in Examples 1-5 and Comparative Examples 1-8 were subjected to performance tests. The test results are shown in Table 1-2.

[0086] The test methods of each embodiment and comparative example are described as follows:

[0087] The tensile strength test was carried out in accordance with ISO 527 standard at a test speed of 50 mm / min.

[0088] The notched impact strength test is carried out in accordance with ISO 179.

[0089] The melt index test was carried out in accordance with ISO1133 standard, with a load of 1.2 kg and a test temperature of 300°C.

[0090] The flame retardant test is carried out in accordance with UL94 standard.

[0091] The thermal stability test uses a 300°C, heat-dwelling injection molding of a 150mm*100mm*2mm sample to observe the silver streaks on the surface. The more silver streaks there are, the worse the thermal stability.

[0092] The S.2 needle flame test follows GB / T4943.1, burning continuously for 300 seconds. A burn-through time exceeding 60 seconds is considered to have passed the S.2 needle flame standard. A longer burn-through time indicates superior burn resistance.

[0093] Table 1 Examples 1-5 and Comparative Examples 1-3

[0094]

[0095]

[0096] Table 2 Comparative Examples 4-9

[0097]

[0098]

[0099] As can be seen from Examples 1-5 in Table 1, the present invention's ternary combination of barium phosphate / zirconium phosphate, boron trioxide / zinc borate, and fumed silica can produce a synergistic flame retardant effect, enhance char formation, improve thin-wall S.2 needle flame performance, and pass the 1.2mm test (burn-through seconds greater than 300s), while maintaining excellent mechanical properties and good thermal stability. Comparative Examples 1-3 show that traditional silicone flame retardant and talc systems can only pass the 1.5mm S.2 needle flame test, and the talc system has very low impact resistance. Comparative Example 3 shows that adding a toughening agent has limited impact improvement and actually deteriorates flame retardancy to a V-1 combustion rating. Comparative Examples 4-6 in Table 2 show that the present invention's ternary composite synergistic flame retardant system is indispensable; otherwise, none of them can pass the 1.2mm S.2 needle flame test. Comparative Example 7 shows that reducing the barium phosphate content to 0.5% has a significant impact on flame retardancy, reducing the combustion rating of the flame-retardant PC system to V-1. Comparative Example 8 shows that the silicon-containing toughening agent MR01 significantly improves impact strength. When MR01 is omitted from this flame-retardant PC system, the impact strength drops sharply. Comparative Example 9 shows that compared to Example 2, when the zirconium phosphate particle size reaches 10 μm, not only does the burn-through resistance drop significantly, but the impact strength also drops sharply.

Claims

1. A flame retardant PC resin composition that meets the thin-wall S.2 needle flame standard, characterized in that: The invention comprises the following components in parts by weight:

2. The flame retardant PC resin composition according to claim 1, wherein: The PC resin has a melt index of 6-20 g / 10 min at 300° C. and a load of 1.2 kg.

3. The flame retardant PC resin composition according to claim 1, wherein: The sulfonate flame retardant is selected from any one or two of potassium perfluorobutanesulfonate, potassium diphenylsulfone-3-sulfonate, and aromatic sulfonate HES.

4. The flame retardant PC resin composition meeting the thin-wall S.2 needle flame standard according to claim 1, characterized in that: The toughening agent is a silicon-containing acrylic core-shell toughening agent, wherein the organic silicone acrylate rubber serves as the core and its content is 50wt%-65wt%. The particle size of the silicon-containing acrylic core-shell toughening agent is 150nm-300nm and its silicon content is 30wt%-70wt%.

5. The flame retardant PC resin composition meeting the thin-wall S.2 needle flame standard according to claim 1, characterized in that: The phosphate is selected from any one of zinc phosphate, zirconium phosphate, barium phosphate, barium hypophosphite, barium metaphosphate, aluminum hypophosphite, zinc hypophosphite, sodium phosphate, and sodium hypophosphite, and the particle size of the phosphate is 2um-8um.

6. The flame retardant PC resin composition meeting the thin-wall S.2 needle flame standard according to claim 1, characterized in that: The boron-containing compound is selected from any one of zinc borate, boron oxide and boric acid.

7. The flame retardant PC resin composition meeting the thin-wall S.2 needle flame standard according to claim 1, characterized in that: The particle size of the fumed silica is 150nm-350nm, and the specific surface area is 150-400m 2 / g.

8. The flame retardant PC resin composition meeting the thin-wall S.2 needle flame standard according to claim 1, characterized in that: The auxiliary agent is selected from one or more of silane coupling agent, titanate coupling agent, hindered phenol antioxidant, phosphite antioxidant, ethylene bisstearamide, polyethylene wax, pentaerythritol stearate, magnesium stearate, calcium stearate, and benzotriazole UV absorber.

9. A method for preparing a flame-retardant PC resin composition that meets the thin-wall S.2 needle flame standard according to any one of claims 1 to 8, characterized in that: The specific steps include: S1. Weigh each component by weight and mix them evenly to obtain a mixed raw material; S2. The mixed raw materials obtained in step S1 are sheared and mixed through a twin-screw extruder. The mixed raw materials are melted, homogenized, stretched, cooled, and pelletized to obtain the flame-retardant PC resin composition that meets the thin-wall S.2 needle flame standard; the screw aspect ratio of the twin-screw extruder is (35-50):1, the screw speed is 300-500 rpm, and the extrusion temperature is 260-280°C.

10. Use of the flame-retardant PC resin composition meeting the thin-wall S.2 needle flame standard according to any one of claims 1 to 8 in the fields of power adapters, new energy batteries, office equipment, electronic appliances, electric control boxes, and switches.

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