Burthrough-resistant PC composite material and preparation method thereof

Abstract

The invention relates to the field of high polymer materials, in particular to a burnthrough-resistant PC composite material and a preparation method thereof. According to the burnthrough-resistant PC composite material provided by the invention, the bromine flame retardant, the silicon flame retardant and the boron flame retardant are used as one of the components, during combustion, bromine is used for absorbing free radicals, so that the oxidation reaction is slow, heat is reduced, silicon and boron are crosslinked to form a B-Si vitrification protection layer, heat insulation and oxygen insulation are realized, the compactness of a carbon layer is complemented, a sinking carbon layer is formed, and matrix resin is prevented from being combusted; the melt strength of the PC composite material is synergistically improved, burnthrough is prevented, and the PC composite material has excellent burnthrough resistance and meets the requirements of new national standards. The invention further provides a preparation method of the burnthrough-resistant PC composite material, the method is simple in process and high in product benefit, and the technical problem of how to improve the burnthrough resistance of the PC composite material is efficiently solved.

Description

Technical Field

[0001] The invention relates to the field of polymer materials, and in particular to a burn-through resistant PC composite material and a preparation method thereof. Background Art

[0002] Polycarbonate (PC) has good dimensional stability, electrical insulation and flame retardancy, and is widely used in electronic and electrical products. As the country's safety requirements for electrical products become increasingly stringent, national standards are also constantly raising higher requirements. S.2 of GB4943.1-2022 on the flammability test of fireproof enclosures and fireproof baffles requires that the material should not be burned through in a flame for 60 seconds. After high-temperature combustion, polymers will degrade, the molecular weight will drop sharply, and the melt strength will also decrease rapidly. Conventional unmodified 1.5 mm thick PC materials will be burned through in a flame for 20 seconds, which cannot meet the requirements of national standards.

[0003] In order to improve the material's burn-through resistance, on the one hand, it is necessary to establish a protective layer to protect the base material and reduce decomposition, and on the other hand, it is necessary to increase the melt strength of the material at high temperature to prevent dripping. Chinese patent CN115991930B disclosed a polycarbonate composite material and a preparation method thereof on June 7, 2024, which utilizes the "surface-oriented" effect of perfluoroalkyl groups on fluorinated silsesquioxane grafted fluorosilane to form a dense refractory silicon-carbon barrier layer on the surface and provide support to prevent thin-walled parts from being burned through. However, a simple silicon-carbon layer can only block the flame for a short time and cannot form protection during long-term continuous burning. It can be seen that how to improve the burn-through resistance of PC composite materials is still a problem that technicians in this field need to solve. Summary of the invention

[0004] In order to solve the technical problem of how to improve the burn-through resistance of PC composite materials, the present invention provides a burn-through resistant PC composite material, comprising: polycarbonate resin, bromine flame retardant, silicon flame retardant and boron flame retardant; Among them, bromine flame retardant, silicon flame retardant and boron flame retardant are added according to the weight ratio of (2~8): (0.5~3): (0.5~3).

[0005] Furthermore, it also includes: a toughening agent, an antioxidant and a lubricant.

[0006] In one embodiment of the present invention, the polycarbonate resin is bisphenol A polycarbonate, and the melt index is 3-40 g / 10 min.

[0007] In one embodiment of the present invention, the bromine flame retardant is any one of brominated polycarbonate, bromotriazine, and brominated epoxy; The silicon flame retardant is an organic silicon flame retardant; The boron flame retardant is any one of zinc borate, sodium metaborate and polyborosiloxane.

[0008] In one embodiment of the present invention, the toughening agent is any one of methyl methacrylate-butadiene-styrene copolymer and acrylic ester impact agent.

[0009] In one embodiment of the present invention, the antioxidant is prepared by mixing a primary antioxidant and an auxiliary antioxidant in a weight ratio of 1:(1-3).

[0010] Further, the primary antioxidant is a hindered phenol antioxidant; The auxiliary antioxidant is any one of phosphites, mercaptans and thiodipropionate or a mixture of any two of them.

[0011] In one embodiment of the present invention, the lubricant is any one or any combination of pentaerythritol ester, butyl stearate, ethylene bis stearamide and polyolefin wax.

[0012] In one embodiment of the present invention, the composition ratio is as follows in parts by weight: Polycarbonate resin 80~95 parts Bromine flame retardant 2~8 parts Silicon flame retardant 0.5~3 parts Boron flame retardant 0.5~3 parts Toughener 2~8 parts Antioxidant 0.2~0.5 parts Lubricant 0.2~0.5 parts.

[0013] The present invention also provides a method for preparing the burn-through resistant PC composite material as described above, comprising the following steps: The polycarbonate, bromine flame retardant, silicon flame retardant, boron flame retardant, toughening agent, antioxidant and lubricant are mixed uniformly according to weight ratio to obtain a premix; The premix is ​​put into a twin-screw extruder for melt blending and extrusion, stranding and pelletizing, and drying to obtain the burn-through resistant PC composite material; Wherein, the processing temperature of the twin-screw extruder is 230-280°C, and the rotation speed is 50-600 rpm.

[0014] The burn-through resistant PC composite material provided by the present invention is synergistically added with silicon flame retardant, boron flame retardant and bromine flame retardant. During combustion, bromine can absorb free radicals to slow down the oxidation reaction and reduce heat, while silicon and boron can cross-link to form a B-Si glass protective layer, which has heat insulation and oxygen isolation, and supplements the density of the carbon layer. At the same time, a sinking carbon layer is formed to prevent the matrix resin from being burned, thereby comprehensively improving the melt strength of the PC composite material and preventing burn-through.

[0015] The preparation method of the burn-through resistant PC composite material provided by the present invention has simple process and raw material composition and is easy to implement. The prepared burn-through resistant PC composite material has excellent burn-through resistance. The burn-through time of a 1.5 mm thick sample far exceeds the 60 s required in GB 4943.1-2022 S.2, and the benefit is significant.

[0016] In summary, compared with the prior art, the burn-through resistant PC composite material and its preparation method provided by the present invention improve the burn-through resistance of the PC composite material, meet the new requirements of the national standard, have a simple process and high product performance, and effectively solve the technical problem of how to improve the burn-through resistance of the PC composite material. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] The present invention provides the following embodiments 1 to 3 for preparing a burn-through resistant PC composite material: Example 1 By weight, 82 parts of polycarbonate resin, 8 parts of bromine flame retardant, 0.5 parts of silicon flame retardant, 2 parts of boron flame retardant, 6 parts of toughening agent, 0.6 parts of antioxidant and 0.4 parts of lubricant were mixed uniformly to obtain a premix; The premix is ​​put into a twin-screw extruder for melt blending and extrusion, stranding and pelletizing, and drying to obtain the burn-through resistant PC composite material; Wherein, the processing temperature of the twin-screw extruder is 230-280°C, and the rotation speed is 50-600 rpm.

[0019] Example 2 By weight, 86.5 parts of polycarbonate resin, 5 parts of bromine flame retardant, 1.5 parts of silicon flame retardant, 1.5 parts of boron flame retardant, 4 parts of toughening agent, 0.6 parts of antioxidant and 0.4 parts of lubricant were mixed uniformly to obtain a premix; The premix is ​​put into a twin-screw extruder for melt blending and extrusion, stranding and pelletizing, and drying to obtain the burn-through resistant PC composite material; Wherein, the processing temperature of the twin-screw extruder is 230-280°C, and the rotation speed is 50-600 rpm.

[0020] Example 3 By weight, 91.5 parts of polycarbonate resin, 2 parts of bromine flame retardant, 3 parts of silicon flame retardant, 0.5 parts of boron flame retardant, 2 parts of toughening agent, 0.6 parts of antioxidant and 0.4 parts of lubricant were mixed uniformly to obtain a premix; The premix is ​​put into a twin-screw extruder for melt blending and extrusion, stranding and pelletizing, and drying to obtain the burn-through resistant PC composite material; Wherein, the processing temperature of the twin-screw extruder is 230-280°C, and the rotation speed is 50-600 rpm.

[0021] In Examples 1 to 3 of the present invention, preferably, the polycarbonate resin is sabic 2800.

[0022] In Examples 1 to 3 of the present invention, preferably, the bromine flame retardant is American Great Lakes BC-58.

[0023] In Examples 1 to 3 of the present invention, preferably, the silicon flame retardant is Quansheng SI9805.

[0024] In Examples 1 to 3 of the present invention, preferably, the boron flame retardant is zinc borate.

[0025] In Examples 1 to 3 of the present invention, preferably, the toughening agent is Dow Chemical EXL2620.

[0026] In Examples 1 to 3 of the present invention, preferably, the antioxidant is a mixture of Albemarle AT-76 and AT-168 in a weight ratio of 1:1.

[0027] In Examples 1 to 3 of the present invention, preferably, the lubricant is Lonza PETS.

[0028] The present invention also provides the following comparative examples 1 to 3 for preparing a PC composite material: Comparative Example 1 The difference between this comparative example and Example 2 is that no silicon flame retardant and boron flame retardant are added, and the addition ratio of the polycarbonate resin is adjusted to 87.5 parts by weight, and the addition ratio of the toughening agent is adjusted to 6 parts by weight.

[0029] Comparative Example 2 The difference between this comparative example and Example 2 is that no boron flame retardant is added, and the addition ratio of the polycarbonate resin is adjusted to 86 parts by weight, and the addition ratio of the toughening agent is adjusted to 6 parts by weight.

[0030] Comparative Example 3 The difference between this comparative example and Example 2 is that no boron flame retardant is added, and the addition ratio of the polycarbonate resin is adjusted to 92 parts by weight, and the addition ratio of the toughening agent is adjusted to 6 parts by weight.

[0031] For the burn-through resistant PC composite materials prepared in the above Examples 1 to 3 and the PC composite materials prepared in the above Comparative Examples 1 to 3, the burn-through time of the 1.5 mm thick PC composite sample was tested in accordance with GB 4943.1-2022 Audio, video, information technology and communication technology equipment S.2 Flammability test for integrity of fire protection enclosures and fire baffles, and the test results are listed in Table 1.

[0032] Table 1 Burn-through time test table of 1.5 mm PC composite material samples prepared in Examples 1 to 3 and Comparative Examples 1 to 3

[0033] According to the data in Table 1, the burn-through time of the 1.5 mm thick sample of the burn-through resistant PC composite material prepared in Example 2 of the present invention is 165 s, which meets the new requirement of 60 s in GB 4943.1-2022. The burn-through times of the 1.5 mm thick samples of the burn-through resistant PC composite materials prepared in Examples 1 and 3 are 122 s and 78 s, respectively, which also meet the national standard requirements. Among the PC composite materials prepared in Comparative Examples 1 to 3, the burn-through time of the 1.5 mm thick sample is only 42 s of Comparative Example 2 at most, which still cannot meet the national standard requirements.

[0034] PC composite material begins to decompose at 400°C, and the melt strength will decrease rapidly during combustion, and it is easy to burn through. When using bromine flame retardant alone, bromine can absorb free radicals to slow down the oxidation reaction and reduce heat, but the formed carbon layer is still not dense enough, and the flame will continue to burn and consume PC resin, making the burning place easy to burn through, and the residual thickness remaining after burning is thin. In the embodiment of the present invention, silicon flame retardant and boron flame retardant are added, wherein silicon and boron will cross-link to form a B-Si glass protective layer during combustion, which is heat-insulating and oxygen-isolating, improves the density of the carbon layer, and forms a sinking carbon layer to prevent the matrix resin from being burned, comprehensively improving the melt strength of the PC composite material and preventing burn through.

[0035] Although the terms such as burn-through, flame retardant, toughening, anti-oxidation, lubrication, etc. are used more frequently in this article, the possibility of using other terms is not excluded. These terms are used only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional restrictions is contrary to the spirit of the present invention.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A burn-through resistant PC composite material, characterized in that: include: Polycarbonate resin, bromine flame retardant, silicon flame retardant and boron flame retardant; Among them, bromine flame retardant, silicon flame retardant and boron flame retardant are added according to the weight ratio of (2~8): (0.5~3): (0.5~3).

2. The burn-through resistant PC composite material according to claim 1, characterized in that: Also includes: Toughener, antioxidant and lubricant.

3. The burn-through resistant PC composite material according to claim 1, characterized in that: The polycarbonate resin is bisphenol A polycarbonate, and the melt index is 3-40 g / 10 min.

4. The burn-through resistant PC composite material according to claim 1, characterized in that: The bromine flame retardant is any one of brominated polycarbonate, brominated triazine, and brominated epoxy; The silicon flame retardant is an organic silicon flame retardant; The boron flame retardant is any one of zinc borate, sodium metaborate and polyborosiloxane.

5. The burn-through resistant PC composite material according to claim 1, characterized in that: The toughening agent is any one of methyl methacrylate-butadiene-styrene copolymer and acrylic ester impact-resistant agent.

6. The burn-through resistant PC composite material according to claim 1, characterized in that: The antioxidant is prepared by mixing a main antioxidant and an auxiliary antioxidant in a weight ratio of 1:(1-3).

7. The burn-through resistant PC composite material according to claim 6, characterized in that: The main antioxidant is a hindered phenol antioxidant; The auxiliary antioxidant is any one of phosphites, mercaptans and thiodipropionate or a mixture of any two of them.

8. The burn-through resistant PC composite material according to claim 1, characterized in that: The lubricant is any one or any combination of pentaerythritol ester, butyl stearate, ethylene bis stearamide and polyolefin wax.

9. The burn-through resistant PC composite material according to claim 1, characterized in that: The composition ratio is as follows: Polycarbonate resin 80~95 parts Bromine flame retardant 2~8 parts Silicon flame retardant 0.5~3 parts Boron flame retardant 0.5~3 parts Toughener 2~8 parts Antioxidant 0.2~0.5 parts Lubricant 0.2~0.5 parts.

10. A method for preparing the burn-through resistant PC composite material according to any one of claims 1 to 9, characterized in that: The following steps are involved: The polycarbonate, bromine flame retardant, silicon flame retardant, boron flame retardant, toughening agent, antioxidant and lubricant are mixed uniformly according to weight ratio to obtain a premix; The premix is ​​put into a twin-screw extruder for melt blending and extrusion, stranding and pelletizing, and drying to obtain the burn-through resistant PC composite material; Wherein, the processing temperature of the twin-screw extruder is 230-280°C, and the rotation speed is 50-600 rpm.

Images