A flame-retardant anti-dripping agent, its preparation method and application

Abstract

The existing transparent flame-retardant polycarbonate system often needs multiple flame retardants, synergists and anti-dripping agents to be used together, the formula composition is complex, and the compatibility, dispersibility and processing stability among different additives are difficult to be considered simultaneously. The application provides a flame-retardant anti-dripping agent and a preparation method and application thereof, which is prepared from bisphenol S, diphenyl dichlorosilane and phenyl trichlorosilane as raw materials through a substitution reaction. The polycarbonate, the flame-retardant anti-dripping agent, the antioxidant and the lubricant are mixed, melted and extruded to obtain the transparent flame-retardant polycarbonate. The flame-retardant anti-dripping agent of the application is a fluorine-free single structure, when applied to the polycarbonate, no additional polytetrafluoroethylene anti-dripping agent, fluorine-containing sulfonate flame retardant or other flame retardant needs to be added, so that the polycarbonate is endowed with good flame-retardant anti-dripping performance, meanwhile, the transparency of the material is maintained, and the formula is simple, the processing is convenient and the application prospect is wide.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a flame retardant and anti-dripping agent, its preparation method, and its application. Background Technology

[0002] Polycarbonate is a class of engineering plastics with excellent comprehensive properties, including high impact strength, good dimensional stability, heat resistance, and excellent transparency. It is widely used in electronics, lighting devices, automotive parts, rail transportation, building materials, and transparent protective materials. As applications increasingly favor thinner walls, higher safety, and greater transparency, polycarbonate materials not only need to maintain good optical and mechanical properties but also meet higher requirements for flame retardancy and anti-dripping properties.

[0003] Polycarbonate itself possesses a certain degree of self-extinguishing property, but in actual combustion processes, especially in thin-walled products or under vertical combustion conditions, it is still prone to molten dripping. Molten dripping not only causes flame spread but may also ignite surrounding combustibles, significantly increasing the risk of fire. Therefore, suppressing its burning dripping while improving the flame-retardant properties of polycarbonate is a key issue in the flame-retardant modification of polycarbonate.

[0004] Currently, flame-retardant and anti-dripping systems for polycarbonate are typically achieved by combining flame retardants and anti-dripping agents. Flame retardants mainly include sulfonate flame retardants, phosphorus-based flame retardants, silicone flame retardants, and their compound systems; anti-dripping agents are mostly polytetrafluoroethylene (PTFE) materials. Sulfonate flame retardants have high flame-retardant efficiency for polycarbonate, promoting rapid charring and self-extinguishing at low addition levels, and are a commonly used class of flame retardants in polycarbonate flame-retardant modification. However, some high-efficiency sulfonate flame retardants are fluorosulfonates, such as perfluorobutyl sulfonate and perfluoroalkyl sulfonate. Although these flame retardants have high flame-retardant efficiency, their molecular structure contains fluorine, making it difficult to meet the material design requirements of fluorine-free, green, and sustainable development.

[0005] Furthermore, while PTFE-based anti-dripping agents can form a fibrous network structure during processing, thereby improving the melt strength of polycarbonate and suppressing molten dripping, they are themselves fluorine-containing materials. Given increasingly stringent environmental regulations, their use is somewhat limited. Additionally, there is insufficient compatibility between PTFE and the polycarbonate matrix, which can easily lead to increased haze and decreased transparency, making it difficult to meet the application requirements of transparent products.

[0006] Existing transparent flame-retardant polycarbonate systems often require the combined use of multiple flame retardants, synergists, and anti-dripping agents, resulting in complex formulations and difficulties in achieving compatibility, dispersibility, and processing stability among different additives. Multi-component formulations can also lead to problems such as decreased light transmittance, increased haze, reduced mechanical properties, and a narrowed processing window. Particularly for transparent polycarbonate materials, the amount of flame retardant added, the degree of refractive index matching, and the dispersion state all directly affect their optical properties. Summary of the Invention

[0007] This invention addresses the challenges of existing transparent flame-retardant polycarbonate systems, which often require the combined use of multiple flame retardants, synergists, and anti-drip agents, resulting in complex formulations and difficulties in achieving compatibility, dispersibility, and processing stability among different additives. Multi-component formulations can also lead to problems such as decreased light transmittance, increased haze, reduced mechanical properties, and a narrowed processing window. Particularly for transparent polycarbonate materials, the amount of flame retardant added, the degree of refractive index matching, and the dispersion state directly affect their optical properties. This invention provides a flame-retardant and anti-drip agent, its preparation method, and its applications.

[0008] One of the technical solutions of the present invention is to provide a flame retardant and anti-dripping agent, the structural formula of which is as follows: (1) (2) (1) is the local cross-linking structure of the anti-drip agent, and (2) is the structural formula of the anti-drip agent.

[0009] This invention also provides a method for preparing the flame retardant and anti-dripping agent, wherein the reaction formula of the preparation method is as follows: (3) The flame retardant and anti-dripping agent was prepared by substitution reaction using bisphenol S, diphenyldichlorosilane and phenyltrichlorosilane as raw materials.

[0010] Further, the preparation method includes the following steps: adding bisphenol S, acetonitrile, and an acid-binding agent sequentially to a reaction vessel, stirring until homogeneous, and then cooling to -5 to 0°C; dissolving diphenyldichlorosilane and phenyltrichlorosilane in acetonitrile to obtain a mixed solution; slowly adding the mixed solution dropwise to the reaction vessel at -5 to 0°C; after the addition is complete, slowly raising the temperature to 20 to 40°C and continuing the reaction for 12 to 48 hours; after the reaction is complete, filtering the reaction system, collecting the solid product, washing it with deionized water, and then drying it to obtain the flame-retardant and anti-melting dripping agent.

[0011] Furthermore, the acid-binding agent is one of trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, diisopropylethylamine, and N,N,N',N'-tetramethylpropanediamine.

[0012] Furthermore, the molar ratio of bisphenol S to the acid-binding agent is 1:1; based on 1 part by mass of bisphenol S, the amount of acetonitrile used is 15 to 30 parts.

[0013] Furthermore, the total number of moles of chlorine atoms contained in the diphenyldichlorosilane and phenyltrichlorosilane is equal to the total number of moles of phenolic hydroxyl groups contained in the bisphenol S; the molar ratio of the diphenyldichlorosilane to the phenyltrichlorosilane is 100:(0.5-1); and the amount of acetonitrile used is 10-30 parts based on 1 part of the mass of diphenyldichlorosilane.

[0014] The present invention also provides an application of the flame retardant and anti-drip agent, wherein a transparent flame retardant polycarbonate composition is prepared by using the flame retardant and anti-drip agent.

[0015] Further, by weight, the transparent flame-retardant polycarbonate composition comprises the following components: 100 parts polycarbonate, 0.5 to 2 parts flame-retardant and anti-drip agent, 0.1 to 0.2 parts antioxidant, and 0.1 to 0.5 parts lubricant.

[0016] Further, the melt index (300℃ / 1.2 kg) of the polycarbonate is 0.5 to 6.5 g / 10 min; the antioxidant is one or more of antioxidant 168, antioxidant 626, PEP-36 and S-9228; and the lubricant is one or more of pentaerythritol stearate, glyceryl monostearate, butyl stearate and silicone powder.

[0017] Further, polycarbonate, flame retardant and anti-dripping agent, antioxidant and lubricant are added to a mixer in proportion and mixed for 5 to 20 minutes to obtain a premix; the premix is ​​melt-extruded by a twin-screw extruder, cooled and granulated and dried to obtain the transparent flame retardant polycarbonate.

[0018] Compared with the prior art, the present invention has the following advantages: 1) The flame retardant and anti-dripping agent in this invention is a flame retardant and anti-dripping agent with a well-defined structure, good compatibility with polycarbonate, high flame retardant efficiency, and no fluorine. This allows it to impart excellent fluorine-free flame retardant and anti-dripping properties to polycarbonate without the addition of fluorosulfonate flame retardants, polytetrafluoroethylene-based anti-dripping agents, or other flame retardants, while preserving the original transparency of polycarbonate as much as possible. This type of single-structure flame retardant and anti-dripping agent not only simplifies the formulation system and improves processing stability, but also helps to reduce the adverse effects of multi-component compounding on the transparency and overall performance of polycarbonate.

[0019] 2) The flame retardant and anti-dripping agent in this invention has a micro-crosslinked structure. Specifically, the phenolic hydroxyl groups in the bisphenol S molecule undergo a substitution reaction with the silane groups in diphenyldichlorosilane and phenyltrichlorosilane, removing hydrogen chloride and forming aryl-oxygen-silicon bonds (Ar-O-Si). Diphenyldichlorosilane contains two reactive silane groups, primarily serving as connectors and chain extension agents; phenyltrichlorosilane contains three reactive silane groups, acting as branching and crosslinking nodes to connect multiple bisphenol S structural units, thereby constructing a micro-crosslinked organosilicon macromolecule structure with a certain degree of branching and crosslinking density. During polycarbonate melt processing, the aromatic ring structure in the aforementioned micro-crosslinked macromolecules exhibits good structural compatibility with the polycarbonate molecular chains, facilitating the uniform dispersion of the micro-crosslinked macromolecules in the polycarbonate matrix. Simultaneously, the micro-crosslinked macromolecules possess large molecular size, branched structure, and three-dimensional network characteristics, enabling physical entanglement with long polycarbonate molecular chains and allowing the polycarbonate molecular chains to interpenetrate within the micro-crosslinked network, forming a physically interpenetrating network structure. This structure restricts excessive slippage of polycarbonate molecular chains at high temperatures, improving the melt strength and melt stability of the system, thereby reducing melt flow and dripping during combustion. Simultaneously, the sulfonyl and organosilicon structures in the flame retardant and anti-dripping agent promote the formation of a stable char layer during combustion, improving the density and integrity of the char layer, and thus enhancing the flame retardant effect of the condensed phase. The synergistic effect of micro-crosslinking enhancing melt strength and sulfonyl / organosilicon promoting char formation results in polycarbonate materials exhibiting excellent flame retardant and anti-dripping properties.

[0020] 3) The flame retardant and anti-dripping agent in this invention has good compatibility with polycarbonate, is easy to disperse uniformly in the polycarbonate matrix, and can better maintain the original transparency of polycarbonate.

[0021] 4) The preparation method of this invention is simple, and the resulting transparent flame-retardant polycarbonate material has excellent comprehensive properties. This method can be implemented using conventional melt blending and extrusion granulation equipment without the need to modify existing processing equipment, making it suitable for industrial production.

[0022] 5) The transparent flame-retardant polycarbonate composition of the present invention achieves UL-94 V-0 rating at a thickness of 1.6 mm and does not contain PFAS or halogen elements such as chlorine and bromine, and is an environmentally friendly halogen-free flame-retardant polycarbonate material.

[0023] 6) The transparent flame-retardant polycarbonate composition prepared by the present invention is a flame-retardant system for polycarbonate that combines high-efficiency flame retardancy, anti-dripping and transparency retention capabilities. Attached Figure Description

[0024] Figure 1 Transparent demonstration photographs from Examples 4-6; Figure 2The images shown are screenshots of vertical combustion in Examples 4-6 and Comparative Example 1. Detailed Implementation

[0025] The following examples are provided to further illustrate the present invention and are intended to explain the invention, not to limit its scope. Unless otherwise specified, all figures are expressed in parts by weight and weight percentages.

[0026] Unless otherwise specified, the raw materials used in this invention are all conventional commercially available products; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0027] The embodiments of the present invention will be further described below with reference to several examples.

[0028] Example 1: Preparation of flame retardant and anti-dripping agent Bisphenol S (50.05 g, 0.20 mol), acetonitrile (650 mL), and triethylamine (40.48 g, 0.40 mol) were sequentially added to a 1 L three-necked flask, stirred thoroughly, and then cooled to 0 °C. Diphenyldichlorosilane (49.88 g, 0.197 mol) and phenyltrichlorosilane (0.21 g, 0.001 mol) were dissolved in acetonitrile (100 mL) to obtain a mixed solution. This mixed solution was then slowly added dropwise to the three-necked flask; after the addition was complete, the reaction system was heated to 30 °C and the reaction was continued for 24 h. After the reaction was complete, the reaction system was filtered, the solid product was collected, washed with deionized water, and then dried to obtain a flame-retardant and anti-drip agent for polycarbonate.

[0029] Example 2: Preparation of flame retardant and anti-dripping agent Bisphenol S (50.05 g, 0.20 mol), acetonitrile (900 mL), and triethylamine (40.48 g, 0.40 mol) were sequentially added to a 1 L three-necked flask, stirred thoroughly, and then cooled to 0 °C. Diphenyldichlorosilane (49.88 g, 0.197 mol) and phenyltrichlorosilane (0.315 g, 0.0015 mol) were dissolved in acetonitrile (100 mL) to obtain a mixed solution. This mixed solution was then slowly added dropwise to the three-necked flask; after the addition was complete, the reaction system was heated to 30 °C and the reaction was continued for 24 h. After the reaction was complete, the reaction system was filtered, the solid product was collected, washed with deionized water, and then dried to obtain a flame-retardant and anti-drip agent for polycarbonate.

[0030] Example 3: Preparation of flame retardant and anti-dripping agent Bisphenol S (50.05 g, 0.20 mol), acetonitrile (1400 mL), and triethylamine (40.48 g, 0.40 mol) were sequentially added to a 1 L three-necked flask, stirred thoroughly, and then cooled to 0 °C. Diphenyldichlorosilane (49.88 g, 0.197 mol) and phenyltrichlorosilane (0.42 g, 0.002 mol) were dissolved in acetonitrile (100 mL) to obtain a mixed solution. This mixed solution was then slowly added dropwise to the three-necked flask; after the addition was complete, the reaction system was heated to 30 °C and the reaction was continued for 24 h. After the reaction was complete, the reaction system was filtered, the solid product was collected, washed with deionized water, and then dried to obtain a flame-retardant and anti-drip agent for polycarbonate.

[0031] Examples 4-6: Preparation of transparent flame-retardant polycarbonate (1) Add polycarbonate, any flame retardant and anti-dripping agent from Examples 1 to 3, antioxidant and lubricant to the mixer according to the proportions in Table 1, mix for 10 min to obtain premix; (2) The premixed material is melt-extruded by a twin-screw extruder, cooled, granulated and dried to obtain transparent flame-retardant polycarbonate.

[0032] Comparative Examples 1-3: Polycarbonate materials were prepared according to the formulations in Table 1 and the methods described in Examples 4 to 6.

[0033] Table 1 Formulations of Examples 4-6 and Comparative Examples 1-3 (parts by mass)

[0034] The flame retardant properties of the materials prepared in Examples 4-6 and Comparative Examples 1-3 are shown in Table 2.

[0035] Table 2 Performance Comparison Table of Examples 4-6 and Comparative Examples 1-3

[0036] like Figure 1 As shown, the polycarbonate in Examples 4-6 exhibits extremely high transparency, indicating that the addition of the flame retardant did not affect the original transparency of the polycarbonate. After the addition of the flame retardant and anti-dripping agent prepared in Examples 1-3, the polycarbonate in Examples 4-6 all achieved a UL-94 V-0 rating, and no melting or dripping occurred during combustion. Figure 2In contrast, Comparative Example 1, which only added flame retardant KSS, improved the flame retardant properties of polycarbonate but failed to effectively suppress melt dripping; Comparative Example 2, which only added anti-dripping agent PTFE, suppressed combustion dripping but only achieved a flame retardant rating of V-1; Comparative Example 3, which added both flame retardant KSS and anti-dripping agent PTFE, achieved both flame retardant and anti-dripping effects but introduced fluorine into the system. In summary, the polycarbonate materials prepared in Examples 4-6 do not contain PFAS or halogen elements such as chlorine and bromine, and are therefore environmentally friendly halogen-free flame-retardant polycarbonate materials.

[0037] The flame-retardant and anti-dripping mechanism mainly lies in the following: The flame-retardant and anti-dripping agents prepared in Examples 1-3 have a micro-crosslinked structure, which can form a physically entangled or interpenetrating network structure in the polycarbonate matrix, thereby improving the melt strength of the system and inhibiting the molten dripping of the material during combustion. Simultaneously, the sulfonyl and organosilicon structures in the flame-retardant and anti-dripping agents can promote the formation of a stable char layer in polycarbonate during combustion, improving the density and integrity of the char layer, and thus enhancing the flame-retardant effect of the condensed phase. The synergistic effect of micro-crosslinking enhancing melt strength and sulfonyl / organosilicon promoting char formation results in polycarbonate materials exhibiting excellent flame-retardant and anti-dripping properties.

[0038] The transparent flame-retardant polycarbonate composition of this invention maintains transparency while possessing flame-retardant and anti-dripping properties.

[0039] The flame-retardant and anti-dripping agent in this invention has both flame-retardant and anti-dripping functions, and can achieve efficient flame-retardant and anti-dripping modification of polycarbonate materials through a single component.

[0040] The flame retardant and anti-dripping agent in this invention is a fluorine-free single structure. When applied to polycarbonate, it can impart good flame retardant and anti-dripping properties to polycarbonate without the need to add polytetrafluoroethylene-based anti-dripping agents, fluorosulfonate flame retardants or other flame retardants, while maintaining the transparency of the material. It has the advantages of simple formulation, convenient processing and broad application prospects.

[0041] It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0042] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0043] The above embodiments describe in detail the structure, features, and effects of the present invention. The above description is only a preferred embodiment of the present invention. Any changes made in accordance with the concept of the present invention, or equivalent embodiments modified to have equivalent changes, shall still fall within the scope of protection of the present invention if they do not exceed the scope covered by the specification.

[0044] Although embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations, and modifications are possible without departing from the spirit and scope of the invention and the appended claims. Therefore, the scope of the invention is not limited to the contents disclosed in the embodiments.

Claims

1. A flame retardant and anti-dripping agent, characterized in that, The structural formula of the flame retardant and anti-dripping agent is as follows: 。 2. A method for preparing the flame retardant and anti-dripping agent according to claim 1, characterized in that, The reaction formula for the preparation method is: The flame retardant and anti-dripping agent was prepared by substitution reaction using bisphenol S, diphenyldichlorosilane and phenyltrichlorosilane as raw materials.

3. The preparation method according to claim 2, characterized in that, The preparation method includes the following steps: Bisphenol S, acetonitrile, and an acid-binding agent are added sequentially to a reaction vessel, stirred evenly, and then cooled to -5 to 0°C; diphenyldichlorosilane and phenyltrichlorosilane are dissolved in acetonitrile to obtain a mixed solution; the mixed solution is slowly added dropwise to the reaction vessel at -5 to 0°C; after the addition is complete, the temperature is slowly raised to 20 to 40°C, and the reaction continues for 12 to 48 hours; after the reaction is completed, the reaction system is filtered, the solid product is collected, washed with deionized water, and then dried to obtain the flame-retardant and anti-melting dripping agent.

4. The preparation method according to claim 3, characterized in that, The acid-binding agent is one of trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, diisopropylethylamine, and N,N,N',N'-tetramethylpropanediamine.

5. The preparation method according to claim 4, characterized in that, The molar ratio of bisphenol S to the acid-binding agent is 1:1; based on 1 part by mass of bisphenol S, the amount of acetonitrile used is 15 to 30 parts.

6. The preparation method according to claim 5, characterized in that, The total number of moles of chlorine atoms in the diphenyldichlorosilane and phenyltrichlorosilane is equal to the total number of moles of phenolic hydroxyl groups in the bisphenol S; the molar ratio of the diphenyldichlorosilane to the phenyltrichlorosilane is 100:(0.5-1); and the amount of acetonitrile used is 10-30 parts based on 1 part of the mass of diphenyldichlorosilane.

7. The application of the flame retardant and anti-dripping agent according to any one of claims 1 to 6, characterized in that, A transparent flame-retardant polycarbonate composition was prepared using the aforementioned flame-retardant and anti-dripping agent.

8. The application according to claim 7, characterized in that, The transparent flame-retardant polycarbonate composition comprises, by weight, 100 parts polycarbonate, 0.5 to 2 parts flame-retardant and anti-dripping agent, 0.1 to 0.2 parts antioxidant, and 0.1 to 0.5 parts lubricant.

9. The application according to claim 8, characterized in that, The polycarbonate has a melt index (300℃ / 1.2 kg) of 0.5 to 6.5 g / 10 min; the antioxidant is one or more of antioxidant 168, antioxidant 626, PEP-36 and S-9228; the lubricant is one or more of pentaerythritol stearate, glyceryl monostearate, butyl stearate and silicone powder.

10. The application according to claim 9, characterized in that, Polycarbonate, flame retardant and anti-dripping agent, antioxidant and lubricant are added to a mixer in proportion and mixed for 5 to 20 minutes to obtain a premix; the premix is ​​melt-extruded through a twin-screw extruder, cooled and granulated and dried to obtain the transparent flame retardant polycarbonate.

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