Modified polymethylphenylsiloxane flame retardant, transparent flame retardant polycarbonate composition and preparation method thereof

Abstract

The present invention relates to a modified polymethylphenylsiloxane flame retardant, a transparent flame retardant polycarbonate composition and a preparation method thereof. The preparation method of the modified polymethylphenylsiloxane flame retardant is to sulfonate the phenyl group on the polymethylphenylsiloxane to obtain the sulfonated polymethylphenylsiloxane, and then combine with an alkali metal to form a modified polymethylphenylsiloxane flame retardant. The transparent flame retardant polycarbonate composition includes a PC resin and a modified polymethylphenylsiloxane flame retardant in a mass ratio of (95-99.4): (1-4), and other additives. Compared with the prior art, the modified polymethylphenylsiloxane flame retardant of the present invention chemically combines the sulfonate structure and the polymethylphenylsiloxane into one molecule through a chemical reaction, so that after the flame retardant is dispersed into the PC, the combination of the two is still very tight, which is conducive to the flame retardant synergy of the two during the combustion process.

Description

Technical Field

[0001] The invention relates to the field of flame retardant polycarbonate, and in particular to a modified polymethylphenylsiloxane flame retardant, a transparent flame retardant polycarbonate composition and a preparation method thereof. Background Art

[0002] Polycarbonate (PC) is a thermoplastic engineering plastic with excellent comprehensive performance, excellent impact resistance, heat resistance and good optical transparency. It is widely used in electronic appliances, automobiles, optical lenses and other fields. PC itself has a certain flame retardancy, and the vertical burning grade can reach UL-94V-2 level. However, the flame retardancy of PC itself cannot meet some occasions with higher requirements for flame retardancy. Therefore, the flame retardant modification of PC is of great significance.

[0003] Common types of flame retardants for PC include halogen flame retardants, organic phosphate flame retardants, sulfonate flame retardants and organosiloxane flame retardants. Halogen flame retardants are gradually being replaced by other halogen-free flame retardants because they contain halogen elements that are harmful to the human body. Organic phosphate flame retardants have good flame retardant effects, but they have a greater impact on the heat resistance and mechanical properties of PC, and the amount added is generally high.

[0004] A flame retardant thermoplastic molding composition is disclosed in Chinese patent document CN103764761A. The composition comprises an aromatic polycarbonate resin, about 0.01-0.15wt% of an alkali metal salt or alkaline earth metal salt of a perfluoroalkane sulfonic acid, an aromatic sulfimide or an aromatic sulfonic acid, and about 0.5-10wt% of a poly- and / or oligo-aryloxysiloxane as a flame retardant synergist. Although the transparency of the composition is good, the flame retardant effect is poor. Summary of the invention

[0005] The purpose of the present invention is to overcome at least one of the defects of the above-mentioned prior art and to provide a modified polymethylphenylsiloxane flame retardant, a transparent flame retardant polycarbonate composition and a preparation method thereof, in which sulfonate and polymethylphenylsiloxane are tightly combined and have good flame retardancy, transparency, rigidity, toughness and heat resistance.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] The inventors learned that sulfonate and organosiloxane flame retardants have poor flame retardant effects when added alone, but they have a certain synergistic effect after being compounded, which can achieve a better flame retardant effect, and both have little effect on the transparency, heat resistance and mechanical properties of PC. However, current research combines the two flame retardants by physical mixing and then adds them to PC. This combination is not strong enough. After being dispersed in PC, the two flame retardants may separate again, thus affecting the synergistic effect of the two and causing the flame retardant effect to deteriorate. Based on the above findings, the following specific solutions are proposed:

[0008] A modified polymethylphenylsiloxane flame retardant, the structure of which is shown in general formula III, specifically:

[0009]

[0010] Wherein, R1 is methyl, methoxy or hydroxyl, preferably hydroxyl; and M is an alkali metal.

[0011] Furthermore, the alkali metal is lithium, sodium or potassium, preferably sodium or potassium, more preferably potassium.

[0012] A method for preparing the modified polymethylphenylsiloxane flame retardant as described above, comprising sulfonating the phenyl group on the polymethylphenylsiloxane as shown in general formula I to obtain the sulfonated polymethylphenylsiloxane as shown in general formula II, and then combining with an alkali metal to form the modified polymethylphenylsiloxane flame retardant as shown in general formula III;

[0013]

[0014] The specific steps include:

[0015] (1) Preparation of sulfonated polymethylphenylsiloxane: under nitrogen protection, polymethylphenylsiloxane and chlorosulfonic acid are mixed, heated and stirred at a constant temperature, filtered and washed with water to obtain sulfonated polymethylphenylsiloxane;

[0016] (2) Preparation of modified polymethylphenylsiloxane flame retardant: Sulfonated polymethylphenylsiloxane is dispersed in water, heated and stirred at a constant temperature, and an aqueous solution of alkali metal carbonate is added dropwise until the mixed solution is neutral, filtered and washed with water, and dried to obtain the modified polymethylphenylsiloxane flame retardant.

[0017] Further, in step (1), the mass ratio of the polymethylphenylsiloxane to chlorosulfonic acid is 1:(2-5), the temperature of the constant temperature heating and stirring is 40-80°C, the stirring time is 5-12h, and the filtration is suction filtration. The mass ratio of polymethylphenylsiloxane to chlorosulfonic acid is lower than 1:5, the relative content of chlorosulfonic acid is higher, the sulfonation effect of polymethylphenylsiloxane is not significantly increased, and the cost is too high; the mass ratio of polymethylphenylsiloxane to chlorosulfonic acid is higher than 1:2, the relative content of chlorosulfonic acid is lower, and the degree of sulfonation of polymethylphenylsiloxane is lower.

[0018] Furthermore, in step (2), the amount of sulfonated polymethylphenylsiloxane added is: the mass of sulfonated polymethylphenylsiloxane added per 100ml of water is 5-10g, the temperature of the constant temperature heating and stirring is 40-80°C, the stirring time is 1-4h, the concentration of the aqueous solution of alkali metal carbonate is 0.5-1mol / L, the filtration is suction filtration, and the drying condition is: drying at 70-80°C for 6-12h. The mass of sulfonated polymethylphenylsiloxane added per 100ml of deionized water is less than 5g, the concentration of sulfonated polymethylphenylsiloxane is low, the reaction efficiency is low, resulting in a long reaction time and low production efficiency; the mass of sulfonated polymethylphenylsiloxane added is higher than 10g, the dispersion effect of sulfonated polymethylphenylsiloxane in deionized water is poor, it is easy to agglomerate, and the reaction is not sufficient. The concentration of the aqueous solution of alkali metal carbonate is lower than 0.5 mol / L, the concentration of alkali metal carbonate is low, the reaction efficiency is low, resulting in a long reaction time and low production efficiency; the concentration of the aqueous solution of alkali metal carbonate is higher than 1 mol / L, the concentration of alkali metal carbonate is high, and the increase in reaction efficiency is not obvious.

[0019] Furthermore, the molar ratio of phenyl to methyl in the molecule of the polymethylphenylsiloxane is 1:1; the molecular weight of the polymethylphenylsiloxane is 500-5000, preferably 1500-1800.

[0020] A transparent flame-retardant polycarbonate composition comprises a PC resin and the modified polymethylphenylsiloxane flame retardant as described above in a mass ratio of (95-99.4):(1-4), and other additives such as an antioxidant and the like.

[0021] Furthermore, the composition comprises 95-99.4 parts of PC resin, 1-4 parts of modified polymethylphenylsiloxane flame retardant, and 0.1-1 part of antioxidant.

[0022] Preferably, the mass ratio of the PC resin to the modified polymethylphenylsiloxane flame retardant is (95.8-98.9):(1-4). The composition comprises 95.8-98.9 parts of PC resin, 1-4 parts of modified polymethylphenylsiloxane flame retardant, and 0.1-0.2 parts of antioxidant.

[0023] Furthermore, the PC is bisphenol A polycarbonate, and its melt index at 300°C and 1.2kg is 3-10g / 10min, preferably 2-10g / 10min; the antioxidant is selected from one or more of aromatic amine antioxidants, hindered phenol antioxidants, phosphite antioxidants, thioester antioxidants, aromatic phosphates or pentaerythritol esters.

[0024] A method for preparing the transparent flame-retardant polycarbonate composition as described above, the method comprising: adding the components by mass into a high-speed mixer, mixing them thoroughly, and then placing them in a screw machine for extrusion and granulation to obtain the transparent flame-retardant polycarbonate composition; wherein the speed of the screw machine is 300-500 rpm and the temperature is 200-260°C.

[0025] In the prior art, after sulfonate and polymethylphenylsiloxane are physically mixed and dispersed in PC, the distance between the two may become larger, resulting in poor synergistic effect between the two. Compared with the prior art, the modified polymethylphenylsiloxane flame retardant of the present invention chemically combines the sulfonate structure and polymethylphenylsiloxane into one molecule through a chemical reaction, so that after the flame retardant is dispersed in PC, the combination of the two is still very tight, which is conducive to the flame retardant synergy of the two during the combustion process. DETAILED DESCRIPTION

[0026] The following is a detailed description of an embodiment of the present invention. This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiment.

[0027] A transparent flame-retardant polycarbonate composition containing a modified polymethylphenylsiloxane flame retardant and a preparation method thereof, comprising the following steps:

[0028] (1) Preparation of sulfonated polymethylphenylsiloxane: under nitrogen protection, polymethylphenylsiloxane and chlorosulfonic acid are mixed, heated and stirred at a constant temperature, filtered and washed with water to obtain sulfonated polymethylphenylsiloxane; the mass ratio of polymethylphenylsiloxane to chlorosulfonic acid is 1:(2-5), the constant temperature heating and stirring temperature is 40-80° C., the stirring time is 5-12 h, and the filtration is suction filtration;

[0029] (2) Preparation of modified polymethylphenylsiloxane flame retardant: sulfonated polymethylphenylsiloxane is dispersed in deionized water, heated and stirred at a constant temperature, and an aqueous solution of alkali metal carbonate is added dropwise until the pH value of the mixed solution is neutral, filtered and washed with water, and dried to obtain the modified polymethylphenylsiloxane flame retardant; the amount of sulfonated polymethylphenylsiloxane added is 5-10g per 100ml of deionized water, the constant temperature heating and stirring temperature is 40-80°C, the stirring time is 1-4h, the concentration of the aqueous solution of alkali metal carbonate is 0.5-1mol / L, the filtration is suction filtration, and the drying condition is drying at 70-80°C for 6-12h.

[0030] (3) Prepare the following components by weight:

[0031] PC 95-98.9 copies,

[0032] Modified polymethylphenylsiloxane flame retardant 1-4 parts,

[0033] Antioxidant 0.1-1 part;

[0034] The ingredients in step (3) are added into a high-speed mixer, mixed thoroughly, and then placed into a screw machine, the screw machine speed is controlled to be 300-500 rpm, the temperature is controlled to be 200-260° C., and extrusion granulation is performed to obtain a transparent flame-retardant polycarbonate composition containing a modified polymethylphenylsiloxane flame retardant.

[0035] The components and characteristics involved in the following examples and comparative examples are as follows:

[0036] PC1: The melt index at 300°C and 1.2kg is about 2.4g / 10min, such as Mitsubishi M7027BF;

[0037] PC2: The melt index at 300°C and 1.2kg is about 6.5g / 10min, such as Covestro Makrolon3106;

[0038] PC3: The melt index at 300°C and 1.2kg is about 10g / 10min, such as Lotte PC-1100;

[0039] Polymethylphenylsiloxane: R1 is hydroxyl, the molar ratio of phenyl to methyl is 1:1, and the weight average molecular weight is 1500-1600;

[0040] Alkali metal carbonates: potassium carbonate;

[0041] Example 1

[0042] A transparent flame-retardant polycarbonate composition containing a modified polymethylphenylsiloxane flame retardant and a preparation method thereof, the method comprising the following steps:

[0043] (1) Preparation of sulfonated polymethylphenylsiloxane:

[0044] Under nitrogen protection, 8 g of polymethylphenylsiloxane and 16 g of chlorosulfonic acid were mixed, heated at 40° C. with stirring for 12 h, filtered and washed with water three times to obtain sulfonated polymethylphenylsiloxane;

[0045] (2) Preparation of modified polymethylphenylsiloxane flame retardant:

[0046] 5 g of sulfonated polymethylphenylsiloxane was dispersed in 100 ml of deionized water, heated and stirred at 80°C for 1 h, and a 1 mol / L aqueous solution of potassium carbonate was added dropwise until the pH value of the mixture was neutral, filtered and washed with water three times, and dried to obtain a modified polymethylphenylsiloxane flame retardant;

[0047] (3) Prepare the following components by weight:

[0048] PC1 98.8 copies,

[0049] 1 part of modified polymethylphenylsiloxane flame retardant,

[0050] Antioxidant 168 0.2 parts;

[0051] The ingredients in step (3) are added into a high-speed mixer, mixed thoroughly, and then placed into a screw machine. The speed of the screw machine is controlled to be 300 rpm, the temperature is controlled to be 200-260° C., and extrusion granulation is performed to obtain a transparent flame-retardant polycarbonate composition containing a modified polymethylphenylsiloxane flame retardant.

[0052] Example 2

[0053] A transparent flame-retardant polycarbonate composition containing a modified polymethylphenylsiloxane flame retardant and a preparation method thereof, the method comprising the following steps:

[0054] (1) Preparation of sulfonated polymethylphenylsiloxane:

[0055] Under nitrogen protection, 8 g of polymethylphenylsiloxane and 40 g of chlorosulfonic acid were mixed, heated at 80° C. with stirring for 5 h, filtered and washed with water three times to obtain sulfonated polymethylphenylsiloxane;

[0056] (2) Preparation of modified polymethylphenylsiloxane flame retardant:

[0057] 10 g of sulfonated polymethylphenylsiloxane was dispersed in 100 ml of deionized water, heated and stirred at 40°C for 4 h, and a 0.5 mol / L aqueous solution of potassium carbonate was added dropwise until the pH value of the mixture was neutral, filtered and washed with water three times, and dried to obtain a modified polymethylphenylsiloxane flame retardant;

[0058] (3) Prepare the following components by weight:

[0059] PC2 97.8 copies,

[0060] Modified polymethylphenylsiloxane flame retardant 2 parts,

[0061] Antioxidant 168 0.2 parts;

[0062] The ingredients in step (3) are added into a high-speed mixer, mixed thoroughly, and then placed into a screw machine. The speed of the screw machine is controlled to be 300 rpm, the temperature is controlled to be 200-260° C., and extrusion granulation is performed to obtain a transparent flame-retardant polycarbonate composition containing a modified polymethylphenylsiloxane flame retardant.

[0063] Example 3

[0064] A transparent flame-retardant polycarbonate composition containing a modified polymethylphenylsiloxane flame retardant and a preparation method thereof, the method comprising the following steps:

[0065] (1) Preparation of sulfonated polymethylphenylsiloxane:

[0066] Under nitrogen protection, 8 g of polymethylphenylsiloxane and 28 g of chlorosulfonic acid were mixed, heated at 60° C. with stirring for 8 h, filtered and washed with water three times to obtain sulfonated polymethylphenylsiloxane;

[0067] (2) Preparation of modified polymethylphenylsiloxane flame retardant:

[0068] 8 g of sulfonated polymethylphenylsiloxane was dispersed in 100 ml of deionized water, heated and stirred at 60° C. for 3 h, and a 0.8 mol / L aqueous solution of potassium carbonate was added dropwise until the pH value of the mixture was neutral, filtered and washed with water three times, and dried to obtain a modified polymethylphenylsiloxane flame retardant;

[0069] (3) Prepare the following components by weight:

[0070] PC3 95.8 copies,

[0071] 4 parts of modified polymethylphenylsiloxane flame retardant,

[0072] Antioxidant 168 0.2 parts;

[0073] The ingredients in step (3) are added into a high-speed mixer, mixed thoroughly, and then placed into a screw machine. The speed of the screw machine is controlled to be 300 rpm, the temperature is controlled to be 200-260° C., and extrusion granulation is performed to obtain a transparent flame-retardant polycarbonate composition containing a modified polymethylphenylsiloxane flame retardant.

[0074] Comparative Example 1

[0075] A polycarbonate composition and a method for preparing the same, the method comprising the following steps:

[0076] (1) Prepare the following components by weight:

[0077]

[0078] The ingredients of step (1) were added into a high-speed mixer, mixed thoroughly, and then placed into a screw machine. The speed of the screw machine was controlled to be 300 rpm, the temperature was controlled to be 200-260° C., and extruded into granules to obtain Comparative Example 1.

[0079] Comparative Example 2

[0080] A polycarbonate composition and a method for preparing the same, the method comprising the following steps:

[0081] (1) Prepare the following components by weight:

[0082]

[0083] The ingredients of step (1) were added into a high-speed mixer, mixed thoroughly, and then placed into a screw machine. The speed of the screw machine was controlled to be 400 rpm, the temperature was controlled to be 200-260° C., and extruded into granules to obtain Comparative Example 2.

[0084] Test Case

[0085] After melt extrusion granulation, each of the above embodiments and comparative examples were injection molded into vertical combustion and ASTM standard test specimens on an injection molding machine. The vertical combustion test conditions were carried out in accordance with the UL-94 standard system, and the mechanical property test conditions were carried out in accordance with the ASTM standard system. The materials prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to performance tests, and the test results are shown in Table 1.

[0086] Table 1 Test performance results

[0087]

[0088] From the comparative analysis of the test results of Examples 1-3 and Comparative Examples 1-2, it can be seen that the flame retardant effect of the modified polymethylphenylsiloxane flame retardant is better than that of the physically mixed sulfonate and polymethylphenylsiloxane, and the transparent flame retardant polycarbonate composition prepared using the modified polymethylphenylsiloxane flame retardant has good flame retardancy, transparency, rigidity, toughness and heat resistance.

[0089] The content of unmodified siloxane in the comparative example is consistent with that of the modified siloxane in the example, and then sulfonate is added to the comparative example for compounding, resulting in the amount of PC resin in the comparative example being different from that in the example; the overall flame retardant content in the comparative example is higher than that in the example, and theoretically the flame retardant effect should not be lower than that in the example, but the actual flame retardant effect is not as good as that in the example, which can also explain that the modified siloxane in the example has better flame retardant effect.

[0090] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A modified polymethylphenylsiloxane flame retardant, characterized in that: The structure of the flame retardant is shown in general formula III, specifically: Wherein, R1 is methyl, methoxy or hydroxyl; M is lithium, sodium or potassium; The flame retardant is obtained by sulfonating the phenyl group on the polymethylphenylsiloxane as shown in the general formula I, and then combining it with an alkali metal; The molar ratio of phenyl to methyl in the molecule of the polymethylphenylsiloxane as shown in the general formula I is 1:1; the molecular weight is 500-5000.

2. A method for preparing the modified polymethylphenylsiloxane flame retardant as claimed in claim 1, characterized in that: The method comprises sulfonating the phenyl group on the polymethylphenylsiloxane as shown in the general formula I to obtain the sulfonated polymethylphenylsiloxane as shown in the general formula II, and then combining it with an alkali metal to form a modified polymethylphenylsiloxane flame retardant as shown in the general formula III; The specific steps include: (1) Preparation of sulfonated polymethylphenylsiloxane: under nitrogen protection, polymethylphenylsiloxane of general formula I and chlorosulfonic acid are mixed, heated and stirred at a constant temperature, filtered and washed with water to obtain sulfonated polymethylphenylsiloxane of general formula II; (2) Preparation of modified polymethylphenylsiloxane flame retardant: Disperse the sulfonated polymethylphenylsiloxane shown in general formula II in water, heat and stir at a constant temperature, and simultaneously add an aqueous solution of alkali metal carbonate dropwise until the mixed solution is neutral, filter and wash with water, and dry to obtain the modified polymethylphenylsiloxane flame retardant.

3. The method for preparing a modified polymethylphenylsiloxane flame retardant according to claim 2, characterized in that: In step (1), the mass ratio of the polymethylphenylsiloxane represented by the general formula I to chlorosulfonic acid is 1:(2-5), the temperature of the constant temperature heating and stirring is 40-80° C., the stirring time is 5-12 h, and the filtration is suction filtration.

4. The method for preparing a modified polymethylphenylsiloxane flame retardant according to claim 2, characterized in that: In step (2), the amount of the sulfonated polymethylphenylsiloxane as shown in the general formula II added is: the mass of the sulfonated polymethylphenylsiloxane as shown in the general formula II added to every 100 ml of water is 5-10 g, the temperature of the constant temperature heating and stirring is 40-80° C., the stirring time is 1-4 h, the concentration of the aqueous solution of alkali metal carbonate is 0.5-1 mol / L, the filtration is suction filtration, and the drying conditions are: drying at 70-80° C. for 6-12 h.

5. A transparent flame retardant polycarbonate composition, characterized in that: The composition comprises a PC resin and the modified polymethylphenylsiloxane flame retardant as claimed in claim 1 in a mass ratio of (95-99.4):(1-4), and other additives.

6. A transparent flame-retardant polycarbonate composition according to claim 5, characterized in that: Other additives are antioxidants.

7. A transparent flame-retardant polycarbonate composition according to claim 6, characterized in that: The composition comprises 95-99.4 parts of PC resin, 1-4 parts of modified polymethylphenylsiloxane flame retardant and 0.1-1 part of antioxidant.

8. The transparent flame-retardant polycarbonate composition according to claim 6, characterized in that: The PC is bisphenol A polycarbonate, and its melt index at 300°C and 1.2kg is 2-10g / 10min; the antioxidant is selected from one or more of aromatic amine antioxidants, hindered phenol antioxidants, phosphite antioxidants, thioester antioxidants, aromatic phosphates or pentaerythritol esters.

9. A method for preparing the transparent flame-retardant polycarbonate composition according to any one of claims 5 to 8, characterized in that: The method comprises the following steps: adding components by mass into a high-speed mixer, fully mixing, placing the components in a screw machine, extruding and granulating the components, and obtaining a transparent flame-retardant polycarbonate composition; wherein the speed of the screw machine is 300-500 rpm and the temperature is 200-260°C.

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