Polycarbonate composite material, display mask, and outdoor LED display

Abstract

Disclosed are a polycarbonate composite material, a display mask, and an outdoor LED display. The polycarbonate composite material comprises the following components by mass fraction: 30%-75% of polycarbonate, 0%-45% of a high-temperature-resistant resin, 5%-20% of a reinforcing fiber, 8%-12% of a flame retardant, 1%-3% of a synergistic flame retardant, 1%-3% of a toughening agent, and 0.3%-0.6% of a weather-resistant agent. The melting point of the high-temperature-resistant resin is greater than or equal to 260°C, or the glass transition temperature of the high-temperature-resistant resin is greater than or equal to 185°C; the reinforcing fiber comprises one or more of a surface-modified glass fiber and a surface-modified carbon fiber; and the mass fraction of the high-temperature-resistant resin and the mass fraction of the surface-modified carbon fiber are not simultaneously zero.

Description

Polycarbonate composite material, display screen mask and outdoor LED display screen

[0001] This application claims priority to Chinese Patent Application No. 202411127459.8, filed on August 15, 2024, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the technical field of display, in particular to a polycarbonate composite material, a display screen mask and an outdoor LED display screen. BACKGROUND

[0003] A light emitting diode (LED) is a kind of semiconductor electronic element that converts electrical energy into light energy, which has the advantages of energy saving, high efficiency, rich color, fast response speed and long service life, and is widely used in lighting equipment, display screen and electronic indicator light fields. Large screen display screens made of LEDs are mostly used in outdoor scenes such as shopping malls, high-rise buildings and squares. In order to be suitable for long-distance viewing, a point spacing of P6.0 or more (i.e. the distance between the centers of two adjacent pixel points is greater than or equal to 6.0 mm) is generally used. With the development of new infrastructure, smart transportation and Internet of Things application fields and the widening of application scenarios, outdoor LED display screens have begun to develop towards small pitch below P4.0 to provide clearer and more delicate images.

[0004] The display screen mask is a kind of component installed on the surface of the LED display screen module, which can play the roles of anti-glare, improving contrast, improving color uniformity and protection. For outdoor LED display screens, the protection effect of the display screen mask is particularly important. Traditional display screen masks mostly use glass fiber reinforced modified polycarbonate (PC) composite materials. However, such polycarbonate composite materials are prone to deformation when applied to small-pitch outdoor LED display screens, such as local bulging under heat, display picture being blocked, abnormal situations such as black blocks or shadows, etc., which brings poor experience to users. SUMMARY

[0005] The present application is defined by the independent claims attached, and the related improvements are set forth in the dependent claims.

[0006] The present application provides a polycarbonate composite material, a display screen mask and an outdoor LED display screen to solve the problem that traditional polycarbonate composite materials are prone to deformation when applied to small-pitch outdoor LED display screens.

[0007] In a first aspect, the present application provides a polycarbonate composite material, comprising the following components by mass fraction:

[0008] ;

[0009] The high-temperature-resistant resin satisfies: a melting point greater than or equal to 260°C, or a glass transition temperature greater than or equal to 185°C.

[0010] The reinforcing fiber includes one or more of a surface-modified glass fiber and a surface-modified carbon fiber.

[0011] The mass fraction of the high-temperature-resistant resin and the surface-modified carbon fiber is not both 0.

[0012] In one of the embodiments, the polycarbonate composite material includes the following mass fractions of components:

[0013] .

[0014] In one of the embodiments, the polycarbonate composite material includes the following mass fractions of components:

[0015] ;

[0016] The mass fraction of the surface-modified carbon fiber in the polycarbonate composite material is greater than or equal to 5%.

[0017] In some possible implementations, the high-temperature-resistant resin includes one or more of a liquid crystal polymer, a polyphenylenediamide, a polyether ether ketone, a polyetherimide, a polysulfone, a polyphenylsulfone, and a polyethersulfone.

[0018] In some possible implementations, the surface-modified carbon fiber includes a carbon fiber coated with a polymer on the surface.

[0019] In some possible implementations, the polymer includes one or more of a polyurethane, an epoxy resin, and an acrylic acid.

[0020] In some possible implementations, the mass ratio of the polymer to the carbon fiber is (1.5-6):100.

[0021] In some possible implementations, the length of the carbon fiber is 4-8 mm, and the diameter of the carbon fiber is 4-9 μm.

[0022] In some possible implementations, the surface-modified glass fiber includes a glass fiber modified by a silane coupling agent.

[0023] In some possible implementations, the mass ratio of the silane coupling agent to the glass fiber is (0.5-2.5):100.

[0024] In some possible embodiments, the glass fiber has a length of 3 mm to 5 mm and a diameter of 8 μm to 12 μm.

[0025] In some possible embodiments, the toughening agent comprises one or more of ethylene-methyl acrylate copolymer, methyl methacrylate-acrylate copolymer, methyl methacrylate-butadiene-styrene copolymer, ethylene-acrylate-glycidyl methacrylate terpolymer, acrylic toughening agent, and acrylic-silicone rubber-based toughening agent.

[0026] In some possible embodiments, the flame retardant comprises one or more of nitrogen-based flame retardant, phosphorus-based flame retardant, and organic sulfonate-based flame retardant.

[0027] In some possible embodiments, the synergistic flame retardant comprises one or more of organosiloxane, organosilicon resin, silicate, and silicon micropowder.

[0028] In some possible embodiments, the weathering agent comprises a light stabilizer.

[0029] In some possible embodiments, the polycarbonate composite further comprises one or more of antioxidant, lubricant, and anti-dripping agent.

[0030] In some possible embodiments, the antioxidant comprises one or more of hindered phenol antioxidant and phosphite antioxidant.

[0031] In some possible embodiments, the lubricant comprises one or more of organosiloxane-based polymer, fatty acid salt, fatty acid amide, pentaerythritol stearate, erucamide, oleamide, ethylene bis-stearamide, and polyolefin wax.

[0032] In some possible embodiments, the anti-dripping agent comprises one or more of polytetrafluoroethylene, polyvinylidene fluoride, and silicone.

[0033] In the second aspect, the application provides a display screen mask made of the polycarbonate composite as described above.

[0034] In the second aspect, the application provides an outdoor LED display screen comprising the display screen mask as described above.

[0035] The application has at least the following beneficial effects: the melting point of the high-temperature-resistant resin selected in the application is greater than or equal to 260 DEG C or the glass transition temperature is greater than or equal to 185 DEG C, which can significantly improve the strength, rigidity and heat resistance of the polycarbonate composite material, thereby reducing the thermal deformation phenomenon of the polycarbonate composite material in a high-temperature environment. The glass fiber and carbon fiber in the reinforcing fiber are both subjected to surface modification treatment, so that the reinforcing fiber has good compatibility with the resin. The application uses high-temperature-resistant resin and polycarbonate for alloy modification or adds surface-modified carbon fiber for reinforcing modification, and cooperates with components such as flame retardant, synergistic flame retardant, toughening agent and weather-resistant agent in a specific ratio, which greatly improves the comprehensive performance of the composite material such as strength, rigidity, heat resistance, high-temperature creep resistance, flame retardancy and weather resistance. The display mask made of the polycarbonate composite material provided by the application has very excellent heat deformation resistance, and has very few or even no bulging phenomenon when working at a temperature of 100 DEG C and a brightness of 5000 cd / m 2 for more than 4 hours, and has very excellent heat deformation resistance. Embodiments of the application

[0036] In order to facilitate the understanding of the application, the application will be further described in detail below in combination with specific examples. However, the application can be realized in many different forms, and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the application more thorough and comprehensive.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the application belongs. The terms used in the specification of the application herein are only for the purpose of describing specific embodiments of the application, and are not intended to limit the application.

[0038] In the present application, the meaning of "and / or" is any and all combinations of one or more related listed items. The meaning of "at least one" is more than one, such as one, two and more than two. The meaning of "multiple" or "several" is at least two, such as two, three, etc. The meaning of "multiple layers" is at least two layers, such as two layers, three layers, etc., unless otherwise specifically limited. In the description of the application, the meaning of "several" is at least one, such as one, two, etc., unless otherwise specifically limited.

[0039] When a range of values is disclosed, unless otherwise stated the contemplated values are continuous along the stated range. Further, when a range is stated, unless otherwise stated, the range is inclusive of both the minimum and maximum values, and of each integer within the range. Additionally, a range provided for a feature or characteristic can be combined with other ranges provided for the same feature or characteristic. In other words, unless otherwise indicated, all ranges disclosed in the specification are to be understood to encompass any and all sub-ranges subsumed therein.

[0040] Unless otherwise specified, all steps of the methods of the present application can be performed in any order. For example, the method comprises steps (a) and (b) means that the method can comprise steps (a) and (b) performed in sequence, or steps (b) and (a) performed in sequence. For example, the method is mentioned to further comprise step (c) means that step (c) can be added to the method in any order. For example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0041] In the present application, "above" or "below" includes the number itself. For example, below 1 includes 1.

[0042] In the present application, the temperature parameters, unless otherwise specified, allow for constant temperature treatment, and also allow for fluctuations within a certain temperature range. It should be understood that the constant temperature treatment allows for fluctuations within the accuracy range controlled by the instrument. Fluctuations within a range of, for example, ±5°C, ±4°C, ±3°C, ±2°C, ±1°C are allowed.

[0043] In the present application, room temperature refers to indoor temperature, normal temperature or general temperature. Generally, the range of room temperature can be any of the following temperature ranges: 23°C ± 2°C, 25°C ± 5°C or 20°C ± 5°C.

[0044] A light emitting diode (LED) is a semiconductor electronic component that converts electrical energy into light energy. It has the advantages of energy saving, high efficiency, rich color, fast response speed and long service life, and is widely used in lighting devices, display screens and electronic indicator lights. Large-screen display screens made of LEDs are mostly used in outdoor scenes such as shopping malls, high-rise buildings and squares. In order to be suitable for long-distance viewing, a point spacing (i.e. the distance between the centers of two adjacent pixel points) of P6.0 or more is generally used. With the development of new infrastructure, smart transportation and Internet of Things application fields and the widening of application scenarios, outdoor LED display screens have begun to develop towards small pitch below P4.0 in order to provide clearer and more delicate images.

[0045] The display screen mask is a component installed on the surface of the LED display module, which can play a role in anti-glare, improving contrast, improving color uniformity and protection. For outdoor LED display screen, the protection of the display screen mask is particularly important. The traditional display screen mask is mostly made of glass fiber reinforced modified polycarbonate (PC) composite material. PC is a high-performance thermoplastic engineering plastic with high light transmission, good weather resistance and excellent impact resistance, which can be used to prepare LED display screen mask. At present, 10wt.% of glass fiber is added to the commonly used PC for reinforcement and modification, and this PC composite material can withstand high temperature of 40℃~60℃. For LED display screen mask with point spacing P6.0 or more, the traditional PC composite material does not produce obvious thermal deformation when used in outdoor scenes for a long time. However, for LED display screen mask with point spacing P4.0 or less, when the display brightness exceeds 4500 cd / m 2 When the display screen surface temperature exceeds 60℃, even above 80℃ under extreme conditions. Therefore, this PC composite material is prone to thermal deformation when applied to small-pitch outdoor LED display screens, such as local bulging under heat, display picture being blocked, abnormal conditions such as black blocks or shadows, and poor user experience.

[0046] As a prelude to the embodiments of the present application, a method for manufacturing a small-pitch mask for outdoor LED display screen is provided, which uses 70wt.%~80wt.% polyphenylene sulfide as a base material and adds 20wt.%~30wt.% glass fiber for blending modification. Although this composite material can improve the bulging problem of the mask, the material cost is high, and the detailed structure of the mask needs to be optimized, further increasing the cost. Therefore, it is necessary to develop a composite material with high strength, high modulus, excellent heat resistance and low cost, which can effectively solve the problem of easy thermal deformation of small-pitch outdoor LED display screen mask under the condition that the product structure remains unchanged.

[0047] Therefore, an object of the embodiments of the present application is to provide a polycarbonate composite material, a display screen mask and an outdoor LED display screen, to improve large-screen display screens made of LEDs, and especially to solve the problem of easy deformation of traditional polycarbonate composite materials when applied to small-pitch outdoor LED display screens.

[0048] According to the first aspect of the present application, a polycarbonate composite material is provided.

[0049] In some embodiments, the polycarbonate composite material comprises the following mass fractions of components:

[0050] ;

[0051] wherein the high-temperature resistant resin satisfies: a melting point greater than or equal to 260°C, or a glass transition temperature greater than or equal to 185°C;

[0052] The reinforcing fiber includes one or more of surface-modified glass fiber and surface-modified carbon fiber.

[0053] The mass fraction of the high-temperature resistant resin and the surface-modified carbon fiber is not simultaneously 0.

[0054] The melting point of the high-temperature resistant resin selected in the present application is greater than or equal to 260°C or the glass transition temperature is greater than or equal to 185°C, which can significantly improve the strength, rigidity and heat resistance of the polycarbonate composite material, thereby reducing the thermal deformation phenomenon thereof in a high-temperature environment. Both the glass fiber and the carbon fiber in the reinforcing fiber are subjected to surface modification treatment, so that the reinforcing fiber has good compatibility with the resin; at the same time, compared with the glass fiber, the mechanical properties and heat resistance of the carbon fiber are better, and the introduction of an appropriate amount of surface-modified carbon fiber can compensate for the defects of insufficient strength, rigidity and heat resistance of the composite material. The present application uses the high-temperature resistant resin and polycarbonate for alloy modification or adds surface-modified carbon fiber for reinforcing modification, and cooperates with the flame retardant, synergistic flame retardant, toughening agent and weathering agent and other components in a specific ratio, which greatly improves the comprehensive performance of the composite material such as strength, rigidity, heat resistance, high-temperature creep resistance, flame retardance and weather resistance. The display mask made of the polycarbonate composite material provided in the present application has very excellent heat deformation resistance, and has very few or even no bulging phenomenon when continuously working at a temperature of 100°C and a brightness of 5000 cd / m 2 for more than 4 hours.

[0055] In some embodiments, the mass fraction of the polycarbonate (PC) in the PC composite material can be 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70% or 75%.

[0056] In some embodiments, the mass fraction of the high-temperature resistant resin in the PC composite material can be 0%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40% or 45%.

[0057] In some embodiments, the mass fraction of the reinforcing fiber in the PC composite material can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%.

[0058] In some embodiments, the mass fraction of the flame retardant in the PC composite material can be 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5% or 12%.

[0059] In some embodiments, the mass fraction of the synergistic flame retardant in the PC composite material can be 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.6%, 2.8%, or 3%.

[0060] In some embodiments, the mass fraction of the toughening agent in the PC composite material can be 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.6%, 2.8%, or 3%.

[0061] In some embodiments, the mass fraction of the weather-resistant agent in the PC composite material can be 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, or 0.6%.

[0062] In some embodiments, the polycarbonate composite material comprises components with the following mass fractions:

[0063] 。

[0064] In the present application, if a high-temperature-resistant resin with a mass fraction of 40% to 45% is added and blended with PC for modification, the strength, rigidity, and heat resistance of the PC composite material can be greatly improved, regardless of whether the reinforcing fiber contains surface-modified carbon fiber. When the content of the high-temperature-resistant resin is the same, replacing part or all of the surface-modified glass fiber with surface-modified carbon fiber can achieve higher strength, rigidity, and heat resistance.

[0065] In some embodiments, the mass fraction of the PC in the PC composite material can be 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, or 40%.

[0066] In some embodiments, the mass fraction of the high-temperature-resistant resin in the PC composite material can be 40%, 40.5%, 41%, 41.5%, 42%, 42.5%, 43%, 43.5%, 44%, 44.5%, or 45%.

[0067] In some embodiments, the polycarbonate composite material comprises components with the following mass fractions:

[0068] ;

[0069] In some embodiments, the mass fraction of the high-temperature-resistant resin in the PC composite material can be 40%, 40.5%, 41%, 41.5%, 42%, 42.5%, 43%, 43.5%, 44%, 44.5%, or 45%.

[0070] In the present application, the addition of surface-modified carbon fibers with a mass fraction greater than or equal to 5% can significantly improve the strength, rigidity and heat resistance of PC composites without adding high-temperature-resistant resins.

[0071] In some embodiments, the mass fraction of PC in the PC composite can be 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74% or 75%.

[0072] In some embodiments, the mass fraction of surface-modified carbon fibers in the PC composite is 5% to 20%, for example, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%.

[0073] In some embodiments, the mass fraction of surface-modified glass fibers in the PC composite is 0% to 15%, for example, 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15%.

[0074] Optionally, the synthesis process of PC includes one or more of non-phosgene method, semi-phosgene method and phosgene method. Among them, the main raw material of phosgene method is bisphenol A and phosgene, and its process is relatively mature, which is conducive to the production of PC with high molecular weight. Therefore, the present application selects phosgene method PC with higher molecular weight.

[0075] In some embodiments, the PC satisfies the following conditions: the number average relative molecular weight is 20000 to 50000; the melt flow index (MFI) is greater than or equal to 10 g / 10min under the condition of temperature 300℃ and load 1.2 kg.

[0076] In the present application, the high-temperature-resistant resin can be divided into three types of crystalline, semi-crystalline and non-crystalline according to different resin compositions. For crystalline and semi-crystalline high-temperature-resistant resins, the melting point (Melting Point, T m ) should be above 260℃. For non-crystalline high-temperature-resistant resins, the glass transition temperature (Glass Transition Temperature, T g ) should be above 185℃.

[0077] Optionally, the high-temperature-resistant resin includes one or more of liquid crystal polymer, polyphenylenediamide, polyether ether ketone, polyetherimide, polysulfone, polyphenyl sulfone, polyether sulfone. Further optionally, the high-temperature-resistant resin includes one or more of polyetherimide, polysulfone, polyphenyl sulfone and polyether sulfone.

[0078] The high-temperature-resistant resin selected by the present application has a similar bisphenol A structure as PC, so that the high-temperature-resistant resin has certain compatibility with PC at different use amounts, thereby showing good alloy modification effect. The liquid crystal polymer (LCP) is a kind of polymer material with special performance, which not only has the characteristics of high strength and modulus, good tensile and bending resistance, but also has excellent heat resistance and can maintain stable performance at high temperature. The polyphthalamide (PPA) has two forms of semi-crystalline and non-crystalline, and the melting point of the semi-crystalline is about 310℃, which has excellent heat resistance and performs well in high-temperature creep resistance, fatigue resistance and chemical resistance. The polyether ether ketone (PEEK) has excellent high-temperature resistance, and the long-term use temperature can reach 260℃, and also has high strength, high modulus and good chemical corrosion resistance. The polyetherimide (PEI) is an amorphous high-performance thermoplastic plastic, which has excellent heat resistance, a glass transition temperature of 217℃, a long-term use temperature of more than 170℃, high strength, high rigidity, excellent flame retardance and excellent chemical corrosion resistance. The polysulfone (PSU) is a high-performance thermoplastic plastic, which has good heat resistance, a long-term use temperature of 150℃-174℃, high strength, high rigidity, high transparency, good chemical corrosion resistance and good dimensional stability, and the size change is small under different temperature and humidity conditions. The polyphenylsulfone (PPSU) is a high-performance special engineering plastic, which has excellent high-temperature resistance, can maintain stable performance in a wide temperature range, and has a long-term use temperature of more than 180℃, excellent mechanical strength, excellent chemical corrosion resistance and good dimensional stability. The polyethersulfone (PES) is a high-performance special engineering plastic, which has excellent heat resistance, a long-term use temperature of 180℃, a short-term use temperature of more than 220℃, high strength and rigidity, excellent chemical corrosion resistance, good dimensional stability and high transparency.

[0079] It can be understood that the particle size of the high-temperature-resistant resin is not particularly limited. Generally, the high-temperature-resistant resin exists in the form of sheet or powder, and can be made into granular form, and then blended with PC for alloy modification. However, it is difficult to process PEEK powder into granular form.

[0080] Optionally, the surface-modified carbon fiber includes a carbon fiber coated with a polymer on the surface.

[0081] Optionally, the polymer comprises one or more of polyurethane, epoxy resin and acrylic acid. Further optionally, the polymer coated on the surface of the carbon fiber is epoxy resin; or the polymer coated on the surface of the carbon fiber is acrylic acid and polyurethane, and the mass ratio of the acrylic acid and the polyurethane is (1-2):(2-1). As an example, the mass ratio of the acrylic acid and the polyurethane can be 1:1, 1:1.5, 1:2, 2:1 or 2:1.5, and further optionally 1:2.

[0082] In the present application, the polymer such as polyurethane, epoxy resin and acrylic acid coated on the surface of the carbon fiber can enhance the compatibility between the carbon fiber and the resin, avoid the defect that the reinforcing modification effect is not ideal due to poor compatibility, and play an important role in improving the strength, rigidity and heat resistance of the composite material.

[0083] Optionally, the mass ratio of the polymer and the carbon fiber is (1.5-6):100, and further optionally (2.5-4.5):100. As an example, the mass ratio of the polymer and the carbon fiber can be 1.5:100, 2:100, 2.5:100, 3:100, 3.5:100, 4:100, 4.5:100, 5:100, 5.5:100 or 6:100.

[0084] Optionally, the length of the carbon fiber is 4 mm-8 mm, and the diameter is 4 μm-9 μm. Further optionally, the length of the carbon fiber is 5 mm-7 mm, and the diameter is 6 μm-8 μm. As an example, the length of the carbon fiber can be 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, 6.5 mm, 7 mm, 7.5 mm or 8 mm, and the diameter can be 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm or 9 μm.

[0085] In some embodiments, the surface-modified glass fiber comprises a glass fiber modified with a silane coupling agent.

[0086] In the present application, the surface of the glass fiber is modified by using a silane coupling agent, which can enhance the compatibility between the glass fiber and the resin, avoid the defect that the reinforcing modification effect is not ideal due to poor compatibility, and play an important role in improving the strength, rigidity and heat resistance of the composite material.

[0087] In some embodiments, the mass ratio of the silane coupling agent and the glass fiber is (0.5-2.5):100. For example, the mass ratio of the silane coupling agent and the glass fiber can be 0.5:100, 0.8:100, 1:100, 1.2:100, 1.5:100, 1.8:100, 2:100, 2.2:100, 2.4:100, or 2.5:100.

[0088] Optionally, the glass fiber is selected from long glass fiber or chopped glass fiber, and the length of the glass fiber is 3-5 mm and the diameter is 8-12 μm. For example, the length of the glass fiber can be 3 mm, 3.2 mm, 3.8 mm, 4 mm, 4.2 mm, 4.5 mm, 4.8 mm, or 5 mm, and the diameter can be 8 μm, 8.5 μm, 9 μm, 9.5 μm, 10 μm, 10.5 μm, 11 μm, 11.5 μm, or 12 μm.

[0089] In some embodiments, the toughening agent includes one or more of ethylene-methyl acrylate copolymer, methyl methacrylate-acrylate copolymer, methyl methacrylate-butadiene-styrene copolymer, ethylene-acrylate-glycidyl methacrylate terpolymer, acrylic toughening agent, and acrylic-silicone rubber-based toughening agent. Optionally, the toughening agent includes one or more of methyl methacrylate-butadiene-styrene copolymer, ethylene-acrylate-glycidyl methacrylate terpolymer, and acrylic-silicone rubber-based toughening agent.

[0090] The toughening agent selected in the present application has acrylic functional groups or acrylate functional groups, has certain polarity and active functional groups, can play a role at the interface of polymers of different polarity, enhance the interface bonding force, help to improve the compatibility while toughening, reduce phase separation, and improve the performance of the alloy modified material.

[0091] In some embodiments, the flame retardant includes one or more of nitrogen-based flame retardant, phosphorus-based flame retardant, and organic sulfonate-based flame retardant. Optionally, the flame retardant is a phosphorus-based flame retardant. The nitrogen-based flame retardant can include one or more of melamine, melamine cyanurate, melamine phosphate, etc., dicyandiamide, and guanidine compounds. The phosphorus-based flame retardant can include one or more of triphenyl phosphate, bisphenol A-bis(diphenyl phosphate), and resorcinol-bis(diphenyl phosphate). The organic sulfonate-based flame retardant can include one or more of 2,4,5-trichlorobenzenesulfonic acid sodium, benzenesulfonyl benzenesulfonic acid potassium, and potassium perfluorobutyl sulfonate.

[0092] In some embodiments, the synergistic flame retardant includes one or more of organosiloxane, organosilicon resin, silicate, and silicon powder. Optionally, the synergistic flame retardant is organosiloxane.

[0093] In the present application, the synergistic flame retardant refers to an additive that can significantly improve the flame retardant effect and reduce the amount of main flame retardant when used in combination with the main flame retardant in the flame retardant system. Among them, the organosiloxane synergistic flame retardant can assist in flame retardation by promoting charring and releasing inert gas, has good thermal stability, low smoke and low toxicity, and can improve the processability and flowability of the composite material. The use of organosiloxane synergistic flame retardant and phosphorus-based flame retardant in combination can make the PC composite material achieve good flame retardant effect, and maintain good mechanical strength and high transparency.

[0094] In some embodiments, the weathering agent includes a light stabilizer.

[0095] It can be understood that the light stabilizer is a kind of additive that can inhibit or slow down the degradation and aging of high polymer materials under the action of light (mainly ultraviolet light), usually including one or more of ultraviolet absorbers, free radical capturing agents and quenching agents. Among them, the ultraviolet absorber is a kind of additive that can absorb ultraviolet light to protect the material from ultraviolet damage, common ones are benzophenone, benzotriazole and triazine, etc. The free radical capturing agent is a kind of substance that can effectively capture and terminate the free radical chain reaction, which plays an important role in preventing material aging and degradation, common ones are hindered amine compounds such as piperidine derivatives and imidazoline derivatives, and phenolic compounds such as butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). The quencher is a kind of substance that can make the molecule in the excited state return to the ground state through energy transfer or charge transfer, thereby reducing the probability of photochemical reaction, common ones are metal ion quenchers and aromatic quenchers.

[0096] In some embodiments, the weathering agent includes an ultraviolet absorber and a free radical capturing agent. Among them, the ultraviolet absorber includes one or more of benzotriazole ultraviolet absorbers and triazine ultraviolet absorbers; the free radical capturing agent includes hindered amine free radical capturing agent. The mass ratio of ultraviolet absorber and free radical capturing agent is (1~3):(1~3), for example 1:1, 2:1, 3:1, 1:2, 3:2, 1:3 or 2:3.

[0097] In some embodiments, the polycarbonate composite material further includes one or more of antioxidants, lubricants and anti-dripping agents.

[0098] In some embodiments, the polycarbonate composite material further includes the following components with the following mass fractions:

[0099] 。

[0100] By way of example, the antioxidant can have a mass fraction of 0.3%, 0.4%, 0.5%, 0.6% in the PC composite; the lubricant can have a mass fraction of 0.4%, 0.5%, 0.6%, 0.7% or 0.8% in the PC composite; and the anti-dripping agent can have a mass fraction of 0%, 0.1%, 0.2%, 0.3%, 0.4% or 0.5% in the PC composite.

[0101] In some embodiments, the antioxidant comprises one or more of a hindered phenolic antioxidant and a phosphite antioxidant. Optionally, the mass ratio of the hindered phenolic antioxidant and the phosphite antioxidant is (1-2):(1-4), such as 1:1, 2:1, 1:2, 1:3, 2:3 or 1:4.

[0102] In some embodiments, the lubricant comprises one or more of a silicone polymer, a fatty acid salt, a fatty acid amide, pentaerythritol stearate, erucamide, oleamide, ethylene bis-stearamide and a polyolefin wax. Optionally, the lubricant comprises one or more of a silicone polymer, pentaerythritol stearate and ethylene bis-stearamide.

[0103] In some embodiments, the anti-dripping agent comprises one or more of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF) and silicone. Optionally, the anti-dripping agent is polytetrafluoroethylene (PTFE).

[0104] In some embodiments, the method for preparing the PC composite comprises the following steps:

[0105] S100: mixing the PC, the high-temperature-resistant resin, the flame retardant, the synergistic flame retardant, the toughening agent and the weather-resistant agent to prepare a blend;

[0106] S200: mixing the blend and the reinforcing fiber and then performing an extrusion molding process to prepare a molded material;

[0107] S300: performing a granulation process on the molded material to prepare the PC composite.

[0108] In some embodiments, the blend further contains one or more of the antioxidant, the lubricant and the anti-dripping agent.

[0109] In some embodiments, in the mixing process of step S100, a high-speed mixing blender is used as the mixing device, the stirring speed is 400 rpm-800 rpm, and the stirring time is 2 min-3 min.

[0110] In some embodiments, in the extrusion process of step S200, a screw extruder is selected as the extrusion device, the blend enters the extruder through a hopper, and the reinforcing fiber enters the extruder through a side feeder, the main feeder speed is 15 rpm-25 rpm, the side feeder speed is 8 rpm-15 rpm; the extrusion temperature is 250°C-290°C, the screw rotation speed is 350 rpm-450 rpm, and the vacuum degree is-0.02 MPa--0.04 MPa.

[0111] Optionally, the granulation process of step S300 includes processes such as a die, a drawbar, and a granulation.

[0112] Optionally, the particle size of the PC composite material is 1.5 mm-4.0 mm, for example, 1.5 mm, 1.8 mm, 2 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3 mm, 3.2 mm, 3.5 mm, 3.8 mm, or 4 mm.

[0113] Optionally, the tensile strength of the PC composite material is greater than or equal to 72 MPa, and is further optionally 100 MPa-120 MPa.

[0114] Optionally, the flexural modulus of the PC composite material is greater than or equal to 3700 MPa, and is further optionally 4600 MPa-7000 MPa.

[0115] Optionally, the notched Izod impact strength of the PC composite material is greater than or equal to 6 kJ / m 2 , and is further optionally 6.4 kJ / m 2 -10 kJ / m 2 .

[0116] Optionally, the heat distortion temperature of the PC composite material is greater than or equal to 150°C, and is further optionally 153°C-160°C.

[0117] Optionally, the flame retardant level of the PC composite material at a thickness of 1.6 mm is V0 level.

[0118] According to the second aspect of the present application, a display screen mask is provided, which is made of the polycarbonate composite material as described above.

[0119] Optionally, the display screen mask continuously works for more than 4 hours under an environment with a temperature of 100°C and a brightness of 5000 cd / m 2 , and the number of bulges or shadows on the surface is not more than 3.

[0120] According to the third aspect of the present application, an outdoor LED display screen is provided, which includes the display screen mask as described above.

[0121] The following is further illustrated in conjunction with specific examples and comparative examples. The raw materials involved in the following specific examples and comparative examples, if no special instructions, can be sourced from the market, the instruments used, if no special instructions, can be sourced from the market, the process involved, if no special instructions, are routine selection for those skilled in the art.

[0122] Example 1

[0123] Please see Table 1, the PC composite material of the present embodiment is composed of the following components by mass fraction: 。

[0124] Among them, the high-temperature-resistant resin is selected from polyether sulfone (PES); the surface modified glass fiber is a glass fiber modified by silane coupling agent, the length of the glass fiber is 3 mm~5 mm, and the fiber diameter is 8 μm~12 μm; the flame retardant is selected from bisphenol A bis-diphenyl phosphate, the synergistic flame retardant is selected from polysiloxane, the toughening agent is selected from ethylene-acrylic ester-glycidyl methacrylate terpolymer, the weathering agent is selected from benzotriazole UV234, the antioxidant is selected from a combination of hindered phenol 1076 main antioxidant and phosphite 168 auxiliary antioxidant, the lubricant is selected from pentaerythritol stearate, and the anti-dripping agent is selected from polytetrafluoroethylene powder.

[0125] Among them, the preparation method of the PC composite material of the present embodiment is:

[0126] (1) PC, high-temperature-resistant resin, flame retardant, synergistic flame retardant, toughening agent, weathering agent, antioxidant, lubricant and anti-dripping agent are put into a high-speed mixing stirrer, and stirred at a stirring speed of 400 rpm~800 rpm for 2 min~3 min to obtain a uniformly mixed blend.

[0127] (2) The blend is fed into the extruder through the hopper, and the feeding speed is controlled at 15 rpm~25 rpm; the reinforcing fiber is fed into the extruder through the side feeder, and the feeding speed is 8 rpm~15 rpm; the extrusion temperature is set to 250℃~290℃, the screw rotation speed is 350 rpm~450 rpm, and the vacuum degree is-0.02 MPa~-0.04 MPa, and the extrusion molding is carried out to obtain the molding material.

[0128] (3) The molding material is granulated by the processes of die, draw bar and pelletizing, and the PC composite material with a particle size of 1.5 mm~4.0 mm is obtained.

[0129] Examples 2~6

[0130] The formula of the PC composite material of Examples 2~6 is shown in Table 1, and the preparation method is the same as that of Example 1.

[0131] Among them, examples 1~4 add high-temperature-resistant resin polyether sulfone (PES), examples 1~2 do not add surface-modified carbon fibers, and examples 3~4 add surface-modified carbon fibers; example 56 does not add poly high-temperature-resistant resin, but adds surface-modified carbon fibers.

[0132] Comparative examples 1~4

[0133] The formulations of PC composites of comparative examples 1~4 are shown in Table 1, and the preparation method is the same as that of example 1.

[0134] Among them, comparative example 1 does not add poly high-temperature-resistant resin and surface-modified carbon fibers;

[0135] Comparative example 2 is basically the same as example 4, except that comparative example 2 does not add a toughening agent;

[0136] Comparative example 3 is basically the same as example 3, except that comparative example 3 replaces surface-modified carbon fibers with carbon fibers without surface modification;

[0137] Comparative example 4 is basically the same as example 2, except that comparative example 4 replaces surface-modified glass fibers with glass fibers without surface modification.

[0138] Test example

[0139] The PC composites in each example and each comparative example are injection molded, and standard samples and display masks are prepared according to standard requirements. The performance of the PC composites is tested according to the standard test method, and the results are shown in Table 2. The display masks are assembled into LED boxes, and the LED boxes are tested as follows, and the results are shown in Table 3.

[0140] (1) Tensile strength: refer to GB / T 1040.1-2018 Determination of tensile properties of plastics;

[0141] (2) Elongation at break: refer to GB / T 1040.1-2018 Determination of tensile properties of plastics;

[0142] (3) Flexural modulus: refer to GB / T 9341-2000 Test methods for flexural properties of plastics;

[0143] (4) Izod notched impact strength: refer to GB / T 1843-2008 Determination of Izod impact strength of plastics;

[0144] (5) Heat distortion temperature: refer to GB / T 1634.1-2019 Determination of heat distortion temperature of plastics under load;

[0145] (6) Flame retardant level: refer to UL 94 flame retardant level standard.

[0146] (7) LED box temperature aging test: the LED box is placed in an oven, and the box is sequentially lighted and aged at 40℃, 50℃, 60℃, 70℃, 80℃, 90℃ and 100℃. Under the serial condition, at each temperature, 5000 cd / m 2 brightness is used, and the light is turned on for at least 4 hours. When the number of blisters or shadows exceeds 15 per box, the verification is stopped, and the temperature at which the verification is stopped is recorded. The results are shown in Table 3.

[0147] As can be seen from Tables 1-3, the high-temperature-resistant resin is alloyed with PC in Examples 1-2, the surface-modified carbon fiber is used to reinforce and modify the polycarbonate in Examples 5-6, and both of the above two modification treatments are used in Examples 3-4. The strength, rigidity and heat resistance of the PC composite material can be greatly improved. In the temperature aging test of the LED box, the face shield made of the PC composite material of Examples 1-6 has few or even no blister defect problem, indicating that it has very excellent heat deformation resistance and is very suitable for long-term use in small-pitch outdoor LED display screens.

[0148] Table 1. Formulation of PC composite material (unit: wt.%)

[0149]

[0150] Table 2. Performance comparison of PC composite material

[0151]

[0152] Table 3. Temperature aging test results of LED box

[0153]

[0154] Note: “--” in Table 3 means that the verification has been stopped.

[0155] The technical features of the above-described embodiments can be combined arbitrarily. In order to make the description simple, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combinations of the technical features do not contradict, they should be considered as the scope of the present application.

[0156] The above-described embodiments only express several embodiments of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the protection scope of the present application. It should be noted that, for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A polycarbonate composite material, comprising components in the following mass fractions: ； wherein said high-temperature resistant resin satisfies: a melting point greater than or equal to 260℃, or, a glass transition temperature greater than or equal to 185℃; said reinforcing fiber comprises one or more of surface-modified glass fiber and surface-modified carbon fiber; the mass fractions of said high-temperature resistant resin and said surface-modified carbon fiber are not both 0.

2. The polycarbonate composite of claim 1, wherein, said polycarbonate composite material comprises components in the following mass fractions: 。 3. The polycarbonate composite of claim 1, wherein, said polycarbonate composite material comprises components in the following mass fractions: ； wherein the mass fraction of said surface-modified carbon fiber in said polycarbonate composite material is greater than or equal to 5%.

4. The polycarbonate composite material of any one of claims 1 to 3, wherein, said high-temperature resistant resin comprises one or more of liquid crystal polymer, polyphenylamide, polyether ether ketone, polyether imide, polysulfone, polyphenyl sulfone, and polyether sulfone.

5. The polycarbonate composite of claim 4, wherein, said surface-modified carbon fiber comprises carbon fiber coated with polymer, and satisfies one or more of the following conditions: (1) said polymer comprises one or more of polyurethane, epoxy resin, and acrylic acid; (2) the mass ratio of said polymer to said carbon fiber is (1.5-6):100; (3) the length of said carbon fiber is 4 mm-8 mm, and the diameter of said carbon fiber is 4 μm-9 μm.

6. The polycarbonate composite of claim 4, wherein, said surface-modified glass fiber comprises glass fiber modified by silane coupling agent, and satisfies one or more of the following conditions: (1) the mass ratio of said silane coupling agent to said glass fiber is (0.5-2.5):100; (2) the length of said glass fiber is 3 mm-5 mm, and the diameter of said glass fiber is 8 μm-12 μm.

7. The polycarbonate composite of claim 4, wherein, satisfies one or more of the following conditions: (1) said toughening agent comprises one or more of ethylene-methyl acrylate copolymer, methyl methacrylate-acrylate copolymer, methyl methacrylate-butadiene-styrene copolymer, ethylene-acrylate-glycidyl methacrylate terpolymer, acrylic acid-based toughening agent, and acrylic acid-silicone rubber-based toughening agent; (2) said flame retardant comprises one or more of nitrogen-based flame retardant, phosphorus-based flame retardant, and organic sulfonate-based flame retardant; (3) said synergistic flame retardant comprises one or more of organosiloxane, organosilicon resin, silicate, and silicon micropowder; (4) said weathering agent comprises light stabilizer.

8. The polycarbonate composite of claim 4, wherein, said polycarbonate composite material further comprises one or more of antioxidant, lubricant, and anti-dripping agent, and satisfies one or more of the following conditions: (1) said antioxidant comprises one or more of hindered phenol-based antioxidant and phosphite-based antioxidant; (2) said lubricant comprises one or more of organosiloxane-based polymer, fatty acid salt, fatty acid amide, pentaerythritol stearate, erucic acid amide, oleic acid amide, ethylene bis-stearamide, and polyolefin wax; (3) said anti-dripping agent comprises one or more of polytetrafluoroethylene, polyvinylidene fluoride, and silicone.

9. A display screen visor, wherein, made of the polycarbonate composite material according to any one of claims 1-8.

10. An outdoor LED display screen, wherein, comprising the display screen mask according to claim 9.

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