Flame-retardant polycarbonate composition, preparation method therefor and use thereof

Abstract

The present invention relates to the field of flame-retardant carbonates. Specifically, disclosed are a flame-retardant polycarbonate composition, a preparation method therefor and a use thereof. The flame-retardant polycarbonate composition of the present invention comprises the following components in parts by weight: 100 parts of polycarbonate, 0.01-0.1 parts of a sulfonate flame retardant, 0.03-0.1 parts of an anti-dripping agent, and 2-8 parts of talcum powder. The melt flow index of polycarbonate is 5.5-25 g / 10 min; the average particle size of the talcum powder is 4-8 microns, and the pH value of the talcum powder is 7.5-8.8. According to the present invention, by controlling the particle size and the pH value range of the talcum powder, the flame-retardant polycarbonate composition has excellent flame resistance of 5 VA at 2.0 mm, also has the advantages of high mechanical strength and environmental protection, and is particularly suitable for electronic and electrical products.

Description

A flame retardant polycarbonate composition and its preparation method and application Technical Field

[0001] The invention belongs to the field of flame retardant carbonates, and particularly relates to a flame retardant polycarbonate composition, a preparation method and an application thereof. Background Art

[0002] Polycarbonate (PC) is an engineering plastic with excellent performance and good comprehensive properties, such as high mechanical strength, good impact resistance, dimensional stability, good heat resistance, and good electrical insulation. Based on these excellent properties of PC, it is widely used in home appliances, digital products, IT products and other fields. With the application and development of PC products in various industries, certain requirements are also put forward for its flame retardant properties.

[0003] Sulfonate flame retardants are highly effective flame retardants for polycarbonate. Their mechanism of action is that the thermal decomposition products of sulfonates during the initial combustion phase promote Fris rearrangement in polycarbonate, inducing the rapid formation of a dense carbon layer on the surface of the part, isolating it from oxygen and heat, thus preventing combustion. The higher the sulfonate flame retardant dosage, the better the flame retardant effect. However, this flame retardant is currently regulated by REACH, requiring the material dosage to be controlled within 1000 ppm. Therefore, the flame retardancy level of polycarbonate flame retardants using this flame retardant system is limited. Currently, mature flame retardant systems on the market can only meet 1.5mm V-0 and 3.0mm 5VA flame retardancy levels. With the trend toward thinner-walled electronic and electrical components, the demand for flame retardant materials has increased to 2.0mm 5VA flame retardancy. Existing flame retardant systems struggle to achieve this thin-wall 2.0mm 5VA flame retardancy requirement. Failures primarily manifest as dripping and ignition of the vertically burning spline and perforation of the square plate. In addition, although other flame retardant systems have been reported to achieve 2.0mm 5VA, this may result in the materials not meeting REACH or halogen-free environmental protection requirements, or may result in poor mechanical properties or heat resistance, making them unable to meet the material usage requirements of the electronics and electrical industry.

[0004] In short, in order to obtain high strength, 2.0mm 5VA flame retardancy and meet REACH environmental protection control, the material needs to be further optimized and modified.

[0005] Summary of the Invention

[0006] In view of the problems that the polycarbonate flame retardant materials involved in the above-mentioned prior art do not meet environmental protection requirements and have poor flame retardancy and mechanical properties, the present invention will provide a flame retardant polycarbonate composition and its preparation method and application.

[0007] To achieve the above objectives, the following technical solutions are specifically included:

[0008] A flame retardant polycarbonate composition comprises the following components in parts by weight:

[0009] 100 parts of polycarbonate, 0.01-0.1 parts of sulfonate flame retardant, 0.03-0.1 parts of anti-dripping agent, and 2-8 parts of talc; the polycarbonate has a melt index of 5.5-25 g / 10 min, wherein the melt index is tested in accordance with ISO 1133-1 2011 standard under the test conditions of 300° C. and 1.2 kg; the talc has an average particle size of 4-8 microns, and a pH value of 7.5-8.8.

[0010] The pH test method of talc comprises the following steps: weighing 30 g of talc into a polytetrafluoroethylene beaker, pouring 100 mL of deionized water, stirring magnetically at 80° C. for 60 min, stopping stirring, cooling to 25° C., and filtering with suction, and testing the pH value of the filtrate using a pH meter, which is the pH value of the talc.

[0011] The first step in the Fris rearrangement of polycarbonate's flame retardant carbonization is degradation. Alkalinity can accelerate polycarbonate degradation, and the alkalinity of talc can accelerate this degradation step, accelerating the rearrangement during flame retardancy testing and forming a larger, stronger carbon layer for flame retardancy. However, excessive talc alkalinity can cause severe PC degradation, significantly reducing the material's notched impact strength. Excessive degradation also leads to low melt strength, resulting in drip ignition failure in the 5VA burning strip test. Too low talc alkalinity may not catalyze the degradation of polycarbonate to a sufficient degree, resulting in unsatisfactory flame retardancy.

[0012] The talc powder of the specific particle size and alkalinity range of the present invention has two functions. On the one hand, the appropriate alkalinity of the talc powder is used to catalyze the Fris rearrangement of PC to catalyze the formation of the carbon layer. On the other hand, the flaky structure of the talc powder plays an effect similar to "reinforced concrete" in the process of carbon layer formation. Enhancing the strength of the carbon layer helps to achieve the flame retardant 5VA and avoid the failure of the square plate to burn through. The larger the particle size of the talc powder, the stronger the enhancement effect and the easier it is to pass the 5VA test. Therefore, to a certain extent, the flame retardant performance is enhanced by increasing the particle size of the talc powder. However, if the particle size of the talc powder is too large, it will lead to more defects at the junction of the talc powder and the resin, and the notched impact strength of the material will be significantly reduced. If the particle size of the talc powder is too small, the reinforcing effect of the talc powder when participating in the carbon layer structure is insufficient, and it is not enough to form a strong carbon layer, resulting in poor flame retardant effect. Therefore, the particle size of the talc powder also needs to be selected within a suitable range.

[0013] The average particle size of talc can be 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8 microns, etc., as well as specific values ​​between the above points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific points included in the range.

[0014] As a preferred embodiment of the present invention, the talc powder has a flake structure.

[0015] As a preferred embodiment of the present invention, the mass percentage of the talc in the polycarbonate composition is 4%-7%.

[0016] As a preferred embodiment of the present invention, the pH value of the talc is 8.4-8.7.

[0017] The average particle size of talc powder is often measured using conventional methods. Specifically, the average particle size D50 of talc powder particles can be measured by laser diffraction, grid screening method, etc. Commonly used equipment includes Malvern dry / wet laser particle size analyzer.

[0018] As a preferred embodiment of the present invention, the melt index of the polycarbonate is 6 to 19 g / 10 min, wherein the melt index is tested according to ISO 1133-1 2011 standard under the test conditions of 300° C. and 1.2 kg.

[0019] The sulfonate flame retardant may include various organic sulfonate flame retardants, including organic sulfonates having at least one carbon atom. The organic sulfonate may be an alkali metal salt, such as a sodium salt, a potassium salt, a lithium salt, or a cesium salt, or an alkaline earth metal salt, such as a magnesium salt, a calcium salt, a strontium salt, or a barium salt, or may be a salt of a metal element such as iron, tin, or zinc, an ammonia salt, or an organic alkylamine salt.

[0020] The organic group of the organic sulfonate can be substituted by a halogen atom (such as fluorine, chlorine or bromine). Among the halogen atoms, fluorine is most preferred, and alkali metal salts or alkaline earth metal salts of perfluoroalkylsulfonic acids represented by the general formula (CnF2n+1SO3)mM are common, wherein n represents a natural number from 1 to 10, M represents lithium, sodium, potassium and cesium, or magnesium, calcium, strontium and barium, and m is equal to the valence of M, 1 or 2. More specifically, perfluoromethanesulfonate, perfluoroethanesulfonate, perfluoropropanesulfonate, perfluorobutanesulfonate, perfluorohexanesulfonate, perfluoroheptanesulfonate, perfluorooctanesulfonate and the like can be used. Among them, potassium perfluorobutanesulfonate is particularly suitable.

[0021] Specifically, at least one of alkylsulfonates, benzenesulfonates, alkylbenzenesulfonates, diphenylsulfonates, naphthalenesulfonates, 2,5-dichlorobenzenesulfonate, 2,4,5-trichlorobenzenesulfonate, diphenylsulfone-3-sulfonate, diphenylsulfone-3,3'-disulfonate, naphthalenetrisulfonate, and fluorine-substituted products thereof can be used.

[0022] As a further preferred embodiment of the present invention, the weight portion of the sulfonate flame retardant is 0.05-0.1 parts.

[0023] As a preferred embodiment of the present invention, the weight content of the sulfonate flame retardant in the polycarbonate composition is not higher than 1000 ppm.

[0024] As a preferred embodiment of the present invention, the anti-dripping agent is polytetrafluoroethylene (PTFE).

[0025] A method for preparing a flame retardant polycarbonate composition comprises the following steps:

[0026] The method comprises the following steps: uniformly mixing polycarbonate, sulfonate flame retardant, talcum powder and anti-dripping agent, and then melting and extruding to granulate to obtain the flame retardant polycarbonate composition.

[0027] As a preferred embodiment of the present invention, the extrusion temperature is 230-280°C.

[0028] As a preferred embodiment of the present invention, the extrusion temperature is 230-260°C.

[0029] The invention discloses a flame-retardant polycarbonate composition which is applied in electronic and electrical products, and can meet the requirements of electronic and electrical products for mechanical and flame-retardant properties. The composition can be applied to flame-retardant plastic parts of audio equipment, televisions, computers, cameras and the like.

[0030] Compared with the prior art, the present invention has the following beneficial effects: the present invention can, in a low-content sulfonate flame retardant system (10-1000 ppm), by controlling the particle size and pH range of talc powder, enable the flame-retardant polycarbonate composition to have excellent 2.0 mm 5VA flame retardant performance, while also having the advantages of high mechanical strength and environmental protection, and is particularly suitable for electronic and electrical products. DETAILED DESCRIPTION

[0031] To better illustrate the objectives, technical solutions, and advantages of the present invention, the present invention will be further described below with reference to specific examples. The experimental methods used in the examples and / or comparative examples are conventional methods unless otherwise specified; the materials and reagents used are commercially available unless otherwise specified.

[0032] Talc pH test:

[0033] Weigh 30 g of talc powder and put it into a polytetrafluoroethylene beaker. Pour in 100 mL of deionized water and stir magnetically at 80 °C for 60 min. Stop stirring, cool to 25 °C, and filter with suction. Test the pH value of the filtrate using a pH meter.

[0034] Talc surface treatment:

[0035] Weigh 30g of talc powder and put it into a polytetrafluoroethylene beaker, pour in 100mL of glacial acetic acid, stir magnetically at room temperature for a certain period of time to react, then filter and dry the talc powder in a 60℃ oven for 60min. By controlling the reaction time of talc powder in glacial acetic acid, the pH value of the surface of the treated talc powder can be adjusted.

[0036] Raw material information:

[0037] Polycarbonate 1#: PC 7030R, melt index 4.2g / 10min, Mitsubishi, Japan;

[0038] Polycarbonate 2#: PC WY-106BR, melt index 6g / 10min, Lihuayi;

[0039] Polycarbonate 3#: PC 2100, melt index 10g / 10min, Wanhua Chemical;

[0040] Polycarbonate 4#: PC 2220, melt index 19g / 10min, Wanhua Chemical;

[0041] Polycarbonate 5#: PC H-3000F, melt index 30g / 10min, Mitsubishi, Japan;

[0042] Polycarbonate 6#: PC S-3000VR, melt index 15g / 10min, Mitsubishi, Japan;

[0043] The test method for the polycarbonate melt index is as follows: in accordance with ISO 1133-1 2011 standard, the test conditions are 300°C / 1.2kg.

[0044] Sulfonate flame retardant: potassium perfluorobutane sulfonate SC4, Jiangxi Guohua Chemical;

[0045] Anti-dripping agent: polytetrafluoroethylene AD541, Changshu Zhenfu New Materials Co., Ltd.

[0046] Talc 1: TY90-13C, average particle size D50 8.0 μm, pH 8.7, Dongguan Sanzhi New Materials Co., Ltd.

[0047] Talc 2: TY90-20-A, average particle size D50 8.5 μm, pH 8.7, Dongguan Sanzhi New Materials Co., Ltd.

[0048] Talc 3: HTP Ultra 5L, average particle size D50: 0.65 μm, pH: 8.5, Liaoning Aihai Yimi Mining Co., Ltd.

[0049] Talc 4: TYT-3000A, average particle size D50: 4.2 μm, pH: 8.4, Guangzhou Tianyuan Chemical Co., Ltd.

[0050] Talc 5: FQ-5C, average particle size D50 of 5.12 μm, pH 9.2, from Yingluo Fuquan Stone Powder Factory, Haicheng City. Talc 5 was subjected to the following talc surface treatment to prepare talc 5-1 to talc 5-4, all with the same average particle size D50 of 5.12 μm.

[0051] Talc 5-1: Treated with glacial acetic acid for 10 minutes, pH value is 8.7;

[0052] Talc 5-2: Treated with glacial acetic acid for 30 minutes, pH value is 7.1;

[0053] Talc 5-3: treated with glacial acetic acid for 19 minutes, pH value is 7.5;

[0054] Talc 5-4: Treated with glacial acetic acid for 14 minutes, pH value is 8.4.

[0055] Test method for flame retardant polycarbonate composition:

[0056] Izod notched impact strength: Prepared according to ISO 180-2019 standard A-notch, take 5 standard specimens, use a 2.75J pendulum to test the energy required to break the specimens, and calculate the Izod notched impact strength value of the specimens.

[0057] 5VA specimen test method: Prepare specimens according to UL 94 2016. Use a 125mm flame, contacting the specimen at half its height. Apply the flame for 5 seconds and then remove it for 5 seconds, for a total of 5 times. Record the burning state and time of the specimen after the fifth application of the flame. Do not allow the specimen to drip, ignite the absorbent cotton underneath, or burn for more than 60 seconds.

[0058] 5VA square plate test method: prepare specimens according to UL 94 standard, use a 125mm flame, use half the height of the flame to contact the square plate, flame the square plate for 5 seconds and then remove it for 5 seconds, a total of 5 times, during the 5 flame application process, the square plate is not allowed to be burned through.

[0059] 2.0mm 5VA flame retardant performance requirements: The extinguishing time of the fifth specimen test shall not exceed 60s and no dripping shall ignite the absorbent cotton underneath. At the same time, the square plate shall not be burned through after 5 flame applications.

[0060] Examples 1-11 and Comparative Examples 1-8

[0061] Examples 1-11 and Comparative Examples 1-8 A method for preparing a flame retardant polycarbonate composition comprises the following steps:

[0062] The polycarbonate resin, sulfonate flame retardant, talc powder and anti-dripping agent are mixed evenly, and then melted and extruded into granules through a twin-screw extruder. The temperature range of the screw melting and extrusion is 230-260°C, and the speed range is 30-80rpm.

[0063] Table 1 (in parts by weight)

[0064] Table 2 (in parts by weight)

[0065] It can be seen from the above examples that the notched impact strength of the flame-retardant polycarbonate composition is ≥500 J / m, which meets the mechanical strength required for practical applications. The fifth extinguishing time of the 5VA spline test is 3-50s. The 5VA spline test does not drip and ignite the absorbent cotton underneath, and the 5VA square plate does not burn through, that is, it meets the 2.0mm 5VA flame retardant performance.

[0066] It can be seen from Examples 2-5, 8-9 and Comparative Example 3 that even if the pH value of talc is in the range of 7.5-8.8, the average particle size is greater than the range of 4-8 microns, resulting in more defects at the bonding point between talc and resin, and the notched impact strength of the flame retardant polycarbonate composition drops sharply; it can be seen from Example 4 and Comparative Example 4 that the pH is in the range of 7.5-8.8, but the average particle size is less than the range of 4-8 microns, and the talc does not enhance the strength of the carbon layer of the flame retardant polycarbonate composition (which helps to achieve flame retardancy 5VA) to a small extent, resulting in unqualified flame retardancy.

[0067] It can be seen from Example 5 and Comparative Examples 5-6 that even if the average particle size of talc is in the range of 4-8 microns, when the pH value is less than the range of 7.5-8.8, the alkalinity is too low, the degree of catalytic degradation of polycarbonate is insufficient, and the flame retardant effect is not ideal; when the pH value of talc is greater than the range of 7.5-8.8, the alkalinity of talc is too high, which will cause serious degradation of PC, and the notched impact strength of the material will be significantly reduced. Moreover, due to the excessive degree of degradation, the melt strength of the material is too low, resulting in a failure effect of dripping ignition in the 5VA combustion test of the specimen.

[0068] It can be seen from Examples 2, 6-8 and Comparative Examples 7-8 that when the talc content is too little, the flame retardant properties of the flame-retardant polycarbonate composition are poor; when the talc content is too much, the compatibility with polycarbonate is poor and the dispersion effect is poor, resulting in a significant decrease in its flame retardant properties and impact strength. When the weight proportion of talc is 2-7 parts, the impact strength is relatively ideal.

[0069] As can be seen from Examples 1-3, 11, and Comparative Examples 1-2, the higher the polycarbonate melt index, the lower the molecular weight, and the higher the content of reactive end groups, the more sensitive it is to the alkalinity of talc. The polycarbonate in the composition is more susceptible to degradation due to the alkalinity of talc. Therefore, high flowability (excessive melt index) leads to poor flame retardancy. Consequently, the talc of the present invention, with a pH value of 7.5-8.8, is too alkaline for the PC of Comparative Example 2, and thus fails to achieve a flame retardant effect. Therefore, in the system of the present invention, a specific polycarbonate melt index, talc particle size, and pH range must be met simultaneously to obtain a flame-retardant polycarbonate composition having high mechanical strength, excellent flame retardancy, and compliance with environmental requirements.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A flame retardant polycarbonate composition, characterized in that: The composition comprises the following components in parts by weight: 100 parts of polycarbonate, 0.01-0.1 parts of sulfonate flame retardant, 0.03-0.1 parts of anti-dripping agent, and 2-8 parts of talc; the melt index of the polycarbonate is 5.5-25g / 10min, wherein the melt index is tested according to ISO 1133-12011 standard, and the test conditions are 300°C and 1.2kg; the average particle size of the talc is 4-8 microns, and the pH value of the talc is 7.5-8.

8.

2. The flame retardant polycarbonate composition according to claim 1, characterized in that The weight content of the sulfonate flame retardant in the polycarbonate composition is not higher than 1000 ppm.

3. The flame retardant polycarbonate composition according to claim 1, characterized in that The talc powder has a flaky structure; the mass percentage of the talc powder in the polycarbonate composition is 4%-7%.

4. The flame retardant polycarbonate composition according to claim 1, characterized in that The pH value of the talc is 8.4-8.

7.

5. The flame retardant polycarbonate composition according to claim 1, characterized in that The polycarbonate has a melt index of 6 to 15 g / 10 min.

6. The flame retardant polycarbonate composition according to claim 1, characterized in that The sulfonate flame retardant includes at least one of alkyl sulfonate, benzene sulfonate, alkylbenzene sulfonate, diphenyl sulfonate, naphthalene sulfonate, 2,5-dichlorobenzene sulfonate, 2,4,5-trichlorobenzene sulfonate, diphenyl sulfone-3-sulfonate, diphenyl sulfone-3,3'-disulfonate, naphthalene trisulfonate and fluorine-substituted products thereof.

7. The flame retardant polycarbonate composition according to claim 1, characterized in that The anti-drip agent is polytetrafluoroethylene.

8. A method for preparing the flame retardant polycarbonate composition according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: uniformly mixing polycarbonate, sulfonate flame retardant, talcum powder and anti-dripping agent, and then melting and extruding granulation to obtain the flame retardant polycarbonate composition.

9. Use of the flame retardant polycarbonate composition according to any one of claims 1 to 7 in electronic and electrical products.

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