Flame-retardant polycarbonate film

Abstract

The invention discloses a flame-retardant PC (polycarbonate) film. The flame-retardant PC film comprises the following components in parts by weight: 75-92 parts of PC resin and 10-20 parts of a flame retardant. Wherein the flame retardant comprises a phosphorus-containing flame retardant and an inorganic silicon flame retardant. According to the flame-retardant PC film, the oxygen index of the film is improved through high-molecular-weight PC. The silicon-containing copolymerized PC resin is selected, so that the toughness of the film is greatly enhanced, and meanwhile, the film has a certain synergistic effect on flame retardance. And through compounding of the phosphorus-containing flame retardant and the inorganic silicon flame retardant, the flame retardant effect is improved. Moreover, the flame-retardant PC film also has a good improvement effect on mechanical properties such as rigidity of PC resin, and the negative influence of a phosphorus-containing flame retardant on heat resistance and long-time thermal aging is greatly improved. Therefore, the flame-retardant PC film with good rigidity and toughness is prepared.

Description

Technical Field

[0001] The present application relates to the field of films, and in particular to a flame retardant polycarbonate film. Background Art

[0002] Electronic devices or components need to be wrapped in protective cases to protect them from impact during packaging and transportation. Some protective cases also need to be thin, flame-retardant, and transparent to allow for easy observation of the device's status and mitigate the effects of localized high temperatures, thereby protecting the proper functioning of various electronic devices or components. Summary of the Invention

[0003] The present application provides a flame-retardant polycarbonate (PC) film, which is used for protective shells to protect electronic devices or components. The flame-retardant PC film can meet the flame retardancy requirements of electronic devices or components and has good mechanical strength and transparency.

[0004] In a first aspect, the present application provides a flame-retardant PC film comprising 75 to 92 parts by weight of PC resin and 10 to 20 parts by weight of a flame retardant, wherein the flame retardant comprises a phosphorus-containing flame retardant and an inorganic silicon flame retardant.

[0005] According to the first aspect above, the inorganic silicon flame retardant includes a silicon dioxide inorganic substance coated with siloxane.

[0006] According to the first aspect above, the flame-retardant PC film comprises 80 to 90 parts by weight of PC resin.

[0007] According to the first aspect above, the PC resin comprises 55 to 77 parts by weight of a high molecular weight PC resin and 15 to 25 parts by weight of a silicon-containing copolymerized PC resin.

[0008] According to the first aspect above, the high molecular weight PC resin is at least one of aromatic polycarbonate, aliphatic polycarbonate and aromatic-aliphatic polycarbonate.

[0009] According to the first aspect above, the high molecular weight PC resin has a molecular weight of 18,000 to 35,000 g / mol, a melt index range of 1 to 5, and a glass transition temperature of 140 to 150°C.

[0010] According to the first aspect above, the silicon content of the silicon-containing copolymerized PC resin is 5-20%.

[0011] According to the first aspect above, the flame retardant includes 3 to 10 parts by weight of a phosphorus-containing flame retardant and 3 to 10 parts by weight of an inorganic silicon flame retardant.

[0012] According to the above-mentioned first aspect, the phosphorus-containing flame retardant includes at least one of triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, trixylphenyl phosphate, tris(2,4,6-trimethylphenyl) phosphate, tris(2,4-di-tert-butylphenyl) phosphate, phenoxycyclotriphosphazene, tris(2,6-di-tert-butylphenyl) phosphate, resorcinol bis(diphenyl phosphate), hydroquinone bis(diphenyl phosphate), bisphenol A-bis(diphenyl phosphate), resorcinol bis(2,6-di-tert-butylphenyl phosphate), and hydroquinone bis(2,6-dimethylphenyl phosphate).

[0013] According to the first aspect above, the flame retardant further comprises 0 to 0.2 parts by weight of a sulfonate flame retardant.

[0014] According to the first aspect above, the sulfonate flame retardant includes at least one of perfluorobutane sulfonate and potassium benzenesulfonate.

[0015] According to the first aspect above, the weight ratio of the toughening agent is 0 to 4 parts.

[0016] According to the above first aspect, the toughening agent includes at least one of methyl methacrylate-butadiene-styrene copolymer, methyl methacrylate-acrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-butyl acrylate copolymer, ethylene-acrylate-glycidyl methacrylate terpolymer, and methyl methacrylate-acrylate-dimethylsiloxane copolymer toughening agents.

[0017] According to the first aspect above, the toughening agent includes at least one toughening agent selected from the group consisting of methyl methacrylate-butadiene-styrene copolymer, methyl methacrylate-acrylate copolymer, and methyl methacrylate-acrylate-dimethylsiloxane copolymer.

[0018] According to the first aspect, the flame-retardant PC film comprises an upper film layer, a middle film layer, and a lower film layer, wherein the upper film layer, the middle film layer, and the lower film layer are first combined together through a coextrusion process, a gluing process, or a hot press lamination process to form the flame-retardant PC film. The upper film layer, the middle film layer, and the lower film layer comprise a total of 75 to 92 parts by weight of PC resin and 10 to 20 parts by weight of a flame retardant.

[0019] According to the first aspect, the upper film layer and the lower film layer comprise PC resin and a flame retardant, and the middle film layer comprises PC resin. The combined thickness of the upper film layer and the lower film layer is 50-95% of the total thickness of the flame-retardant PC film, and the thickness of the middle film layer is 5-50% of the total thickness of the flame-retardant PC film.

[0020] According to the first aspect, the upper film layer and the lower film layer comprise PC resin, and the middle film layer comprises PC resin and a flame retardant. The combined thickness of the upper film layer and the lower film layer is 5 to 50% of the total thickness of the flame-retardant PC film, and the thickness of the middle film layer is 50 to 95% of the total thickness of the flame-retardant PC film.

[0021] In a second aspect, the present application provides a protective shell for protecting electronic devices, wherein the protective shell is made of the flame-retardant PC film described in any one of the first aspects.

[0022] By considering the following detailed description, drawings and claims, other features, advantages and embodiments of the present application can be set forth or become apparent. In addition, it should be understood that the above-mentioned summary of the invention and the following detailed description are exemplary and are intended to provide further explanation without limiting the scope of the claimed application. It should also be understood that, although specific component arrangements are disclosed and shown in these exemplary embodiments, other arrangements may also be within the scope of the present application. However, the detailed description and specific examples only indicate preferred embodiments of the present application. For those skilled in the art, various changes and modifications within the spirit and scope of the present application will become apparent through this detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1A Schematic diagram of the structure of a flame-retardant PC film according to one embodiment of the present application;

[0024] Figure 1B Schematic diagram of the structure of a flame-retardant PC film according to another embodiment of the present application;

[0025] Figure 2 Schematic diagram of the structure of an electrical device including an embodiment of the flame-retardant PC film of the present application. DETAILED DESCRIPTION

[0026] Various specific embodiments of the present application will be described below with reference to the accompanying drawings that form a part of this specification. It should be understood that although directional terms such as "front," "back," "up," "down," "left," "right," "top," "bottom," "inside," and "outside" are used in this application to describe various example structural parts and elements of the present application, these terms are used herein for convenience of description only and are determined based on the example orientations shown in the accompanying drawings. Because the embodiments disclosed in this application can be arranged in different orientations, these directional terms are intended to be illustrative only and should not be considered as limiting.

[0027] In this application, unless otherwise specified, all equipment and raw materials can be purchased from the market or are commonly used in the industry. The methods in the following embodiments, unless otherwise specified, are conventional methods in the art.

[0028] PC (polycarbonate) plastic is a high-performance engineering plastic that combines excellent rigidity and toughness. Its inherent transparency, coupled with its rigid molecular chain structure, results in excellent creep resistance, dimensional stability, and high heat resistance. Therefore, films made from PC plastic are ideally suited for manufacturing protective cases for electronic devices or components, providing both protection and easy viewing.

[0029] Films used to manufacture protective cases for electronic devices or components also require excellent flame retardancy. The inventors of the application discovered that the flame retardancy of a film is related to its thickness. Generally speaking, the thicker the film, the better the flame retardancy. However, thicker films cannot meet the requirements of lightweight and miniaturized electronic components. Although PC plastic generally has good self-extinguishing flame retardancy (e.g., 3mm UL V-2 level), when the thickness of PC plastic is small (e.g., less than 1mm), the flame retardancy does not meet the required standards.

[0030] To meet the flame retardancy requirements for thin films, PC plastic must be compounded with flame retardants to produce flame-retardant PC film. The inventors of this application have discovered that the flame retardant properties of flame-retardant PC film are also related to the amount of flame retardant added to the film. Generally speaking, the greater the amount of flame retardant added, the better the flame retardant effect. However, increasing the amount of flame retardant added can lead to a decrease in the film's mechanical properties and processing performance, as well as surface unevenness. Furthermore, to minimize the environmental impact of flame retardants, halogen-free flame retardants are required. Halogen-free flame retardants are expensive, so increasing their use can lead to increased production costs.

[0031] The present application provides a flame-retardant PC film, which is obtained by adding a compounded halogen-free flame retardant to PC resin. Through the synergistic effect between the halogen-free flame retardants, the flame retardancy of the flame-retardant PC film can be improved while controlling the total addition amount of the flame retardant and the film thickness.

[0032] The flame-retardant PC film of the present application comprises a PC resin and a flame retardant. The PC resin comprises 75 to 90 parts by weight, and the flame retardant comprises 10 to 20 parts by weight. In some embodiments, the PC resin comprises 80 to 90 parts by weight. In some embodiments, the PC resin is a compound of a high molecular weight PC resin and a silicon-containing copolymer PC resin.

[0033] The high molecular weight PC resin is present in an amount of 55 to 78 parts by weight. The high molecular weight PC resin is at least one of an aromatic polycarbonate, an aliphatic polycarbonate, and an aromatic-aliphatic polycarbonate. In some embodiments, the high molecular weight PC resin has a molecular weight of 18,000 to 35,000 g / mol, a melt index of 1 to 5, and a glass transition temperature of 140 to 150°C. In some embodiments, the high molecular weight PC resin has a molecular weight of 30,000 to 35,000 g / mol. In some embodiments, the high molecular weight PC resin is prepared by an ester exchange method or a phosgene method.

[0034] The weight proportion of the silicon-containing copolymerized PC resin is 15 to 25 parts, wherein the silicon content of the silicon-containing copolymerized PC resin is 5 to 20%.

[0035] The flame retardant includes a phosphorus-containing flame retardant and an inorganic silicon flame retardant, wherein the phosphorus-containing flame retardant is present in an amount of 3 to 10 parts by weight and the inorganic silicon flame retardant is present in an amount of 3 to 10 parts by weight. In some embodiments, the flame retardant further includes a sulfonate flame retardant, wherein the sulfonate flame retardant is present in an amount of 0 to 0.2 parts by weight.

[0036] The phosphorus-containing flame retardant may include a conventional halogen-free phosphorus-containing flame retardant. In some embodiments, the phosphorus-containing flame retardant includes at least one of triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, tricresyl phosphate, tris(2,4,6-trimethylphenyl) phosphate, tris(2,4-di-tert-butylphenyl) phosphate, phenoxycyclotriphosphazene, tris(2,6-di-tert-butylphenyl) phosphate, resorcinol bis(diphenyl phosphate), hydroquinone bis(diphenyl phosphate), bisphenol A-bis(diphenyl phosphate), resorcinol bis(2,6-di-tert-butylphenyl phosphate), and hydroquinone bis(2,6-dimethylphenyl phosphate).

[0037] The inorganic silicon flame retardant may include a surface-modified silica inorganic compound. In some embodiments, the inorganic silicon flame retardant includes a silica inorganic compound coated with a siloxane.

[0038] The sulfonate flame retardant may include a conventional halogen-free sulfonate flame retardant. In some embodiments, the sulfonate flame retardant includes at least one of perfluorobutane sulfonate and potassium benzenesulfonylbenzenesulfonate.

[0039] In some embodiments, the flame-retardant PC film further comprises 0 to 4 parts by weight of a toughening agent. The toughening agent may comprise a conventional toughening agent. In some embodiments, the toughening agent comprises at least one of methyl methacrylate-butadiene-styrene copolymer (MBS), methyl methacrylate-acrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-butyl acrylate copolymer, ethylene-acrylate-glycidyl methacrylate terpolymer, and methyl methacrylate-acrylate-dimethylsiloxane copolymer toughening agents. In some embodiments, the toughening agent comprises at least one of methyl methacrylate-butadiene-styrene copolymer (MBS), methyl methacrylate-acrylate copolymer, and methyl methacrylate-acrylate-dimethylsiloxane copolymer (Si-ACR) toughening agents.

[0040] In some embodiments, the flame retardant PC film further comprises an antioxidant in an amount of 0.3 to 1 parts by weight. The antioxidant may comprise a conventional antioxidant. In some embodiments, the antioxidant comprises at least one of 2,6-di-tert-butyl-4-methylphenol, β-(3,5-di-tert-butyl-4-hydroxy-phenyl) propionate, dilauryl thiodipropionate, distearate thiodipropionate, tris(2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-tert-butyl)tetrahydroxyl phosphate, pentaerythritol bisphosphite dioctadecyl ester, and benzofuranone.

[0041] In some embodiments, the flame retardant PC film further comprises an anti-drip agent in an amount of 0 to 1 parts by weight. The anti-drip agent may comprise a conventional anti-drip agent. In some embodiments, the anti-drip agent comprises polytetrafluoroethylene (PTFE). In some embodiments, the anti-drip agent comprises a silicone anti-drip agent or an inorganic anti-drip agent.

[0042] In a more specific embodiment, the flame retardant PC film includes 55 to 77 parts by weight of a high molecular weight PC resin, 15 to 25 parts by weight of a silicon-containing copolymer PC resin, 3 to 10 parts by weight of a phosphorus-containing flame retardant, 3 to 10 parts by weight of an inorganic silicon flame retardant, 0 to 0.2 parts by weight of a sulfonate flame retardant, 0 to 4 parts by weight of a toughening agent, 0.3 to 1 parts by weight of an antioxidant, and 0 to 1 parts by weight of an anti-dripping agent.

[0043] Figure 1A and Figure 1B Schematic diagrams of the structures of two embodiments of the flame retardant PC film according to the present application are shown. Figure 1A The flame retardant PC film 110 shown includes a film monolayer 111, which includes 75 to 92 parts by weight of PC resin and 10 to 20 parts by weight of flame retardant. Figure 1A The method for preparing the flame retardant PC film 110 shown includes the following steps:

[0044] a. The raw materials were weighed in parts by weight and added to a mixing mixer for mixing;

[0045] b. The mixture obtained in step a is blended and granulated by an extruder to obtain flame-retardant PC particles;

[0046] c. The flame-retardant PC particles obtained in step b are dried and extruded into a film to obtain a flame-retardant PC film.

[0047] In some embodiments, the extruder is a twin-screw extruder, the barrel temperature of the twin-screw extruder is 250-280° C., and the screw speed is 300-700 rpm.

[0048] The PC resin matrix in the flame-retardant PC film of this application comprises a suitable ratio of high-molecular-weight PC resin and silicon-containing copolymerized PC resin. Compared to low-molecular-weight PC resins, this improves melt strength during combustion, preventing melt dripping, and also increases the oxygen index of the matrix itself, thereby enhancing the flame retardancy of the PC matrix material without affecting mechanical properties such as rigidity. Furthermore, the silicon-containing copolymerized PC resin and the flame retardant exhibit a synergistic effect, enhancing the flame retardant effect of the flame retardant.

[0049] Furthermore, the flame retardant in the flame-retardant PC film of this application is a compound of an inorganic silicon flame retardant and a phosphorus-containing flame retardant in appropriate proportions. While the flame retardancy of the inorganic silicon flame retardant alone is insufficient to meet the flame retardancy requirements of a flame-retardant PC film, the synergistic effect of the inorganic silicon flame retardant, silicon-containing copolymerized PC resin, and other flame retardants forms a dense, oxygen-isolating protective layer on the melt surface during combustion, causing combustion to spread inward rather than outward, thereby ensuring that the flame-retardant PC film meets the flame retardancy requirements. The flame-retardant PC film of this application can achieve a film-grade flame retardancy of 0.4mm V-0.

[0050] The effects of the flame-retardant PC film 110 of the present application are illustrated below using flame-retardant PC film samples of Examples 1-6 and Comparative Examples 1-4. Table 1 shows the contents of the various components in the flame-retardant PC film 110 samples of Examples 1-6 and Comparative Examples 1-4, and Table 2 shows the performance data of the flame-retardant PC film 110 samples of Examples 1-6 and Comparative Examples 1-4.

[0051] In Examples 1-6 and Comparative Examples 1-4, the molecular weight of the high molecular weight PC resin is 30,000 to 35,000 g / mol, and the melt index ranges from 1 to 5. The silicon content of the silicon-containing copolymerized PC resin is 5% to 20%.

[0052] The phosphorus-containing flame retardant is phenoxy cyclotriphosphazene, the inorganic silicon flame retardant is a silicon dioxide inorganic substance coated with siloxane, and the sulfonate flame retardant is potassium benzenesulfonylbenzenesulfonate.

[0053] The antioxidant was Irganox 168 or 1010 from Ciba.

[0054] The anti-drip agent is polytetrafluoroethylene (PTFE).

[0055] In Examples 1-6 and Comparative Examples 1-4, the flame retardant PC film 110 samples were prepared by the following method:

[0056] a. According to the components and weights shown in Table 1, weigh the corresponding raw materials and add all the raw materials to a mixing mixer for mixing;

[0057] b. The mixture obtained in step a was then blended and granulated through a twin-screw extruder to obtain flame-retardant PC particles. The barrel temperature of the extruder was 250 to 280°C and the screw speed was 300 to 700 rpm.

[0058] c. The flame-retardant PC particles obtained in step b are dried and extruded into a film, which is then cut into standard test pieces of uniform thickness, for example, 0.4 mm or 0.3 mm thick, for performance testing.

[0059] Flame retardancy testing was conducted according to the UL-94 test standard. Tensile strength testing was conducted according to the ASTM test standard. Puncture drop weight testing was conducted according to the ISO 7765 test method. Furthermore, the flame-retardant PC film samples of Examples 1-6 and Comparative Examples 1-4 all appeared transparent and visible.

[0060] Table 1 Components and their weight fractions in Examples 1-6 and Comparative Examples 1-4

[0061]

[0062]

[0063] Table 2 Properties of flame retardant PC film samples of Examples 1-6 and Comparative Examples 1-4

[0064]

[0065] It can be seen from Table 1 and Table 2 above that the flame retardant PC film samples of Examples 1-6 of the present application can basically meet the V-0 flame retardant requirements of 0.4 mm thickness, while Comparative Examples 1-4 cannot meet the flame retardant requirements.

[0066] Specifically, the flame retardants in Comparative Examples 1 and 4 consisted solely of phosphorus-containing flame retardants, and the PC resin in Comparative Example 1 was a low-molecular-weight PC resin, while the PC resin in Comparative Example 4 was a high-molecular-weight resin, with all other components being identical. Neither Comparative Examples 1 nor 4 met the flame retardancy requirement of V0, and the flame retardancy of Comparative Example 1 was even worse, indicating that the flame retardancy of the high-molecular-weight PC resin was slightly better than that of the low-molecular-weight PC resin. The flame retardant in Comparative Example 2 consisted solely of an inorganic silicon flame retardant, but the film sample from Comparative Example 2 showed no flame retardancy, indicating that inorganic silicon flame retardants alone are not flame-retardant. The flame retardant in Comparative Example 3 was compounded with a phosphorus-containing flame retardant, an organosilicon flame retardant, and a sulfonate flame retardant, but Comparative Example 3 also failed to meet the flame retardancy requirement of V0, indicating that the synergistic effect of the organosilicon flame retardant with the phosphorus-containing flame retardant and the sulfonate flame retardant was poor. Furthermore, the tensile strength of Comparative Examples 1, 3, and 4 including phosphorus-containing flame retardants could not be measured after 7 days of heat treatment at 140° C., indicating that the phosphorus-containing flame retardant has a significant negative impact on the heat resistance and long-term heat aging of the film.

[0067] Examples 1-6 all contain flame retardants formulated with a phosphorus-containing flame retardant and an inorganic silicon flame retardant, and all achieve V-0 flame retardancy at a thickness of 0.4 mm. This demonstrates that the inorganic silicon flame retardant can synergistically work with the phosphorus-containing flame retardant to enhance the flame retardancy of flame-retardant PC films. Furthermore, Examples 4-6, which also include a sulfonate flame retardant, further enhance the flame retardancy of the film samples compared to Example 3, achieving V-0 flame retardancy at a thinner thickness of 0.3 mm.

[0068] Moreover, although Examples 1-6 include phosphorus-containing flame retardants, the tensile strength is higher after 7 days of heat treatment at 140°C, indicating that the inorganic silicon flame retardant can also synergize with the phosphorus-containing flame retardant to eliminate the negative effects of the phosphorus-containing flame retardant on the heat resistance of the film and long-term heat aging.

[0069] The PC resin matrix of the film samples of Examples 3-6 includes a high molecular weight PC resin and a silicon-containing copolymerized PC resin. Compared to Examples 1 and 2, the film samples of Examples 3-6 exhibit higher elongation at break, indicating that the PC resin matrix obtained by compounding the high molecular weight PC resin and the silicon-containing copolymerized PC resin can improve the elongation at break of the film samples, thereby providing better toughness. Furthermore, among the 0.3 mm thick film samples, the film samples of Examples 3-6 that include the silicon-containing copolymerized PC resin exhibit better flame retardancy, indicating that the silicon-containing copolymerized PC resin and the flame retardant have a certain synergistic effect, which makes the silicon-containing copolymerized PC resin have a certain promoting effect on flame retardancy.

[0070] Furthermore, the elongation at break of Comparative Example 2, which used an inorganic silicone flame retardant alone, was low, indicating that the inorganic silicone flame retardant had a negative impact on mechanical properties. However, by controlling the addition amount of the inorganic silicone flame retardant within a certain range and combining it with other flame retardants, the flame retardant effect of the film sample was improved without affecting the mechanical properties of the film sample.

[0071] like Figure 1B The flame-retardant PC film shown has a three-layer structure, including an upper film layer 121, a middle film layer 122, and a lower film layer 123. These layers are bonded together via coextrusion, gluing, or hot pressing to form flame-retardant PC film 120. These layers 121, 122, and 123 collectively comprise 75 to 92 parts by weight of PC resin and 10 to 20 parts by weight of a flame retardant.

[0072] In some embodiments, the upper film layer 121 and the lower film layer 123 include PC resin and a flame retardant. The middle film layer 122 includes PC resin but does not include a flame retardant. In some embodiments, the combined thickness of the upper film layer 121 and the lower film layer 123 accounts for 50-95% of the total thickness of the flame-retardant PC film, and the thickness of the middle film layer 122 accounts for 5-50% of the total thickness of the flame-retardant PC film. It should be noted that the formulation content of the upper film layer 121 and the lower film layer 123 can be the same or different, as long as the total content of the upper film layer 121, the middle film layer 122, and the lower film layer 123 is as described above.

[0073] like Figure 1B The method for preparing the flame retardant PC film 120 shown includes the following steps:

[0074] a. The raw materials of the upper film layer, the middle film layer and the lower film layer were weighed by weight percentage and then added to a mixing mixer and mixed;

[0075] b. The mixtures obtained in step a were extruded into three-layer film shapes;

[0076] c. The three-layer film obtained in step b is combined together through a co-extrusion process, a gluing process or a hot pressing process to obtain a flame-retardant PC film 120.

[0077] Applicants have discovered that because at least one of the three layers of flame-retardant PC film 120 is made of PC resin without a flame retardant, when the PC resin and flame retardant content is constant, the flame retardant is concentrated more in the one or two layers containing the flame retardant. This allows flame-retardant PC film 120 to have better flame retardant efficiency or a lower flame retardant content. Furthermore, compared to flame-retardant PC film 110, flame-retardant PC film 120 retains more of the properties of the PC resin, resulting in better puncture resistance.

[0078] The effects of the flame retardant PC film 120 of the present application are illustrated below by using some specific flame retardant PC film samples of Examples 7 to 12. Table 3 shows the thickness of each layer in the flame retardant PC film 120 samples of Examples 7 to 12 and the performance data of the flame retardant PC film 120 samples.

[0079] In Examples 7-12, the total content of the components of each layer of the flame-retardant PC film 120 is the same as that of Example 4. In Examples 7-9, the upper film layer 121 and the lower film layer 123 have the same components and include PC resin and flame retardant (referred to as flame-retardant PC in the table), and the middle film layer 122 includes only PC resin. In Examples 10-12, the upper film layer 121 and the lower film layer 123 have the same components and include only PC resin, and the middle film layer 122 includes PC resin and flame retardant.

[0080] Table 3 Thickness and properties of each layer of the flame retardant PC film samples of Examples 7-12

[0081]

[0082] As can be seen from Table 3, the flame-retardant PC films 120 of Examples 7-12 meet flame retardancy requirements and exhibit excellent mechanical properties. Furthermore, compared to the single-layer flame-retardant PC film 110 (as shown in Example 4 in Table 2), the three-layer flame-retardant PC film 120 exhibits superior flame retardancy and puncture resistance.

[0083] Figure 2 FIG. 1 is a schematic diagram of the structure of an electrical device including an embodiment of the flame retardant PC film of the present application. Figure 2 As shown, electrical device 200 includes a protective housing 201 and an electronic device 202 disposed within protective housing 201. The dashed box depicts electronic device 202. Protective housing 201 is made from any of the flame-retardant PC film samples described in Examples 1-5. Electronic device 202 is surrounded by protective housing 201, allowing protective housing 201 to protect electronic device 202.

[0084] The flame-retardant PC film of the present application can be used to wrap various electronic products or devices to protect them. Such electronic products or devices may be electronic devices such as battery modules, heating coils, or motors.

[0085] The flame-retardant PC film of this application utilizes high-molecular-weight PC to improve the film's oxygen index. By selecting a silicon-containing copolymerized PC resin, the film achieves significant toughness enhancement while also providing a synergistic flame retardancy. Furthermore, the combination of a phosphorus-containing flame retardant and an inorganic silicon flame retardant enhances the flame retardancy. Furthermore, the flame-retardant PC film of this application significantly improves mechanical properties such as rigidity of the PC resin, significantly mitigating the negative effects of phosphorus-containing flame retardants on heat resistance and long-term thermal aging. The result is a flame-retardant PC film with excellent rigidity and toughness.

[0086] The flame-retardant PC film of the present application has many beneficial technical effects. At least some of the technical effects of the flame-retardant PC film of the present application are listed below:

[0087] 1. Reduce the use of halogen-free intumescent flame retardants.

[0088] 2. Even when the insulating flame-retardant film has a very small thickness, it has excellent flame-retardant properties, thus meeting the requirements of miniaturization and lightweighting of electrical components and can be applied to more electrical components.

[0089] 3. Excellent processing performance, capable of continuous and stable production.

[0090] 4. Excellent mechanical properties, with excellent rigidity, toughness, heat resistance and long-term heat aging resistance.

[0091] Although the present disclosure has been described in conjunction with the examples of the embodiments outlined above, it is likely that various alternatives, modifications, variations, improvements, and / or substantial equivalents will be apparent to those skilled in the art, whether known or currently or soon to be foreseen. Therefore, the examples of the embodiments of the present disclosure set out above are intended to be illustrative rather than restrictive. Various changes may be made without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is intended to include all known or earlier developed alternatives, modifications, variations, improvements, and / or substantial equivalents. The technical effects and technical problems in this specification are exemplary rather than restrictive. It should be noted that the embodiments described in this specification may have other technical effects and may solve other technical problems.

Claims

1. A flame retardant PC film, characterized in that include: 75-92 parts by weight of PC resin and 10-20 parts by weight of flame retardant; The flame retardant includes a phosphorus-containing flame retardant and an inorganic silicon flame retardant.

2. The flame retardant PC film according to claim 1, characterized in that: The inorganic silicon flame retardant comprises a silicon dioxide inorganic substance coated with siloxane.

3. The flame retardant PC film according to claim 1, characterized in that: The flame-retardant PC film comprises 80 to 90 parts by weight of PC resin.

4. The flame retardant PC film according to claim 1, characterized in that: The PC resin comprises 55 to 77 parts by weight of a high molecular weight PC resin and 15 to 25 parts by weight of a silicon-containing copolymer PC resin.

5. The flame retardant PC film according to claim 4, characterized in that: The high molecular weight PC resin is at least one of aromatic polycarbonate, aliphatic polycarbonate and aromatic-aliphatic polycarbonate.

6. The flame retardant PC film according to claim 4, characterized in that: The high molecular weight PC resin has a molecular weight of 18000 to 35000 g / mol, a melt index range of 1 to 5, and a glass transition temperature of 140 to 150°C.

7. The flame retardant PC film according to claim 4, characterized in that: The silicon content of the silicon-containing copolymer PC resin is 5-20%.

8. The flame retardant PC film according to claim 1, characterized in that: The flame retardant comprises 3 to 10 parts by weight of a phosphorus-containing flame retardant and 3 to 10 parts by weight of an inorganic silicon flame retardant.

9. The flame retardant PC film according to claim 8, characterized in that: The phosphorus-containing flame retardant includes at least one of triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, tricresyl phosphate, tris(2,4,6-trimethylphenyl) phosphate, tris(2,4-di-tert-butylphenyl) phosphate, phenoxycyclotriphosphazene, tris(2,6-di-tert-butylphenyl) phosphate, resorcinol bis(diphenyl phosphate), hydroquinone bis(diphenyl phosphate), bisphenol A-bis(diphenyl phosphate), resorcinol bis(2,6-di-tert-butylphenyl phosphate), and hydroquinone bis(2,6-dimethylphenyl phosphate).

10. The flame retardant PC film according to claim 1, characterized in that: The flame retardant further comprises 0 to 0.2 parts by weight of a sulfonate flame retardant.

11. The flame retardant PC film according to claim 10, characterized in that: The sulfonate flame retardant includes at least one of perfluorobutane sulfonate and potassium benzenesulfonylbenzenesulfonate.

12. The flame retardant PC film according to claim 1, characterized in that Also includes: The weight proportion of the toughening agent is 0 to 4 parts.

13. The flame retardant PC film according to claim 12, characterized in that: The toughening agent includes at least one of methyl methacrylate-butadiene-styrene copolymer, methyl methacrylate-acrylate copolymer, ethylene-methyl acrylate copolymer, ethylene-butyl acrylate copolymer, ethylene-acrylate-glycidyl methacrylate terpolymer, and methyl methacrylate-acrylate-dimethylsiloxane copolymer toughening agents.

14. The flame retardant PC film according to claim 13, characterized in that: The toughening agent includes at least one of methyl methacrylate-butadiene-styrene copolymer, methyl methacrylate-acrylate copolymer and methyl methacrylate-acrylate-dimethylsiloxane copolymer toughening agents.

15. The flame retardant PC film according to claim 1, characterized in that: The flame retardant PC film comprises an upper film layer, a middle film layer and a lower film layer, wherein the upper film layer, the middle film layer and the lower film layer are first combined together by a co-extrusion process, a glue coating process or a hot pressing process to form the flame retardant PC film; The upper film layer, the middle film layer and the lower film layer contain 75 to 92 parts by weight of PC resin and 10 to 20 parts by weight of flame retardant in total.

16. The flame retardant PC film according to claim 15, characterized in that: The upper film layer and the lower film layer include PC resin and flame retardant, and the middle film layer includes PC resin; The sum of the thickness of the upper film layer and the lower film layer is 50-95% of the total thickness of the flame retardant PC film, and the thickness of the middle film layer is 5-50% of the total thickness of the flame retardant PC film.

17. The flame retardant PC film according to claim 15, characterized in that: The upper film layer and the lower film layer include PC resin, and the middle film layer includes PC resin and flame retardant; The sum of the thickness of the upper film layer and the lower film layer is 5-50% of the total thickness of the flame retardant PC film, and the thickness of the middle film layer is 50-95% of the total thickness of the flame retardant PC film.

18. A protective shell for protecting electronic devices, characterized in that: The protective shell is made of the flame-retardant PC film described in any one of claims 1 to 17.

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