A method for preparing a flame-retardant antistatic degradable film

Abstract

The application discloses a preparation method of a flame-retardant and antistatic degradable film. The film is prepared by blending PLA and PBAT, wherein the ratio of PLA to PBAT is 1:2-1:3. The PLA / PBAT blending system makes the prepared material have complete biodegradation capacity, which helps to improve the environmental problems caused by plastic pollution. The molecular weight of PLA and PBAT is increased by adding a chain extender, the physical performance and hydrolysis resistance of the material are improved, the crystallinity of PLA and PABT is improved by adding calcium carbonate, and the stability of the blending system is improved.

Description

Technical Field

[0001] The invention discloses a method for preparing a flame-retardant, antistatic and degradable film. Background Art

[0002] Polylactic acid (PLA) and polybutylene adipate / terephthalate (PBAT) are two common biodegradable materials on the market. PLA has good physical and mechanical properties, strong mechanical properties, easy processing, and excellent biocompatibility, but it is brittle, lacks toughness, and has poor heat resistance. The heat deformation temperature of pure PLA products is only about 58°C. These limitations make it difficult to be widely used as an engineering plastic.

[0003] Polybutylene adipate / terephthalate (PBAT) has many advantages that PLA does not have: such as good softness, good ductility and impact strength, but its mechanical properties are not as good as PLA.

[0004] PLA and PBAT are blended to form a composite material (PLA / PBAT), which combines the advantages of both materials: good mechanical properties and flexibility, as well as good processability, and can be used in various processing forms such as blow molding, cast film, and injection molding. It also has good biodegradability and can be completely degraded into water, carbon dioxide, and inorganic salts in a short time under specific conditions. The application of PLA / PBAT composite materials is expected to alleviate the increasingly serious environmental pollution problem.

[0005] However, in practical applications, PLA / PBAT materials still have many shortcomings: for example, the composite material has poor overall heat resistance and is flammable. Furthermore, because both PLA and PBAT are insulators, static charges on their surfaces are difficult to dissipate, and prolonged static electricity accumulation can easily lead to fire hazards. Furthermore, the poor compatibility between PLA and PBAT can easily lead to phase separation, reducing the material's macroscopic properties. Furthermore, the addition of antistatic carbon black can significantly reduce its mechanical properties as the amount of added carbon black increases. Summary of the Invention

[0006] In order to overcome the above-mentioned defects, the present invention provides a method for preparing a flame-retardant and antistatic degradable film.

[0007] To achieve the above object, the method for preparing the flame retardant and antistatic degradable film of the present invention comprises the following steps:

[0008] 1) preparing an antistatic agent;

[0009] Take 3-5 parts of superconductive carbon black EC6000JD, 10-15 parts of potassium permanganate, add 30-40 parts of deionized water, place in a beaker, use a stirrer to fully stir for 2 hours, then transfer to a three-necked flask, then slowly add 50-60 parts of 98% concentrated sulfuric acid, then reflux at a constant temperature of 90°C in a water bath for 2 hours, filter after natural cooling, and wash with concentrated hydrochloric acid to remove MnO2 generated during the treatment process, and wash with deionized water until neutral; then take 30-40 parts of 30% concentration hydrogen peroxide and add it to the three-necked flask, condense and reflux at a constant temperature of 60°C for 4 hours, and then wash with deionized water until nearly neutral; then filter, and finally dry in an electric blast drying oven at 100°C for 8 hours to obtain an antistatic agent;

[0010] 2) preparing a silicon-phosphorus composite flame retardant;

[0011] Take 70-80 parts of hexachlorocyclotriphosphazene and 20-25 parts of tetramethyldisiloxane, add 5-10 parts of silane coupling agent KH550 dropwise into a beaker, place in a 60°C water bath and stir for 3 hours. After the reaction is complete, filter with a suction flask, place the filtered precipitate in a 50°C electric blast drying oven and dry for 4 hours to obtain a silicon-phosphorus composite flame retardant.

[0012] 3) Preparation of PLA / PBAT plastic rice;

[0013] Take 50-75 parts of PLA, 25 parts of PBAT, 1-3 parts of ADR-4468 chain extender, 1-3 parts of antioxidant 168, and 20-30 parts of nano calcium carbonate and dry them; add the above raw materials after mixing and dispersing, extrude them into a twin-screw extruder, and air-cool them to form granules.

[0014] 4) Preparation of thin films;

[0015] Take 90-95 parts of PLA / PBAT plastic rice after granulation and cutting, 1-3 parts of antistatic additive, 1-3 parts of flame retardant, 1-3 parts of lubricant, 3-5 parts of POE grafted GMA compatibilizer, and dry;

[0016] The above raw materials were mixed and dispersed and then added into a twin-screw extruder. The screw and barrel temperatures were 155°C, 155°C, 160°C, 165°C, and 165°C, and the die head temperature was 165°C and 165°C. The screw speed was 150r / min, the production speed was 15kg / h, and a finished plastic film with a thickness of about 3.5C was produced.

[0017] 5) Corona treatment of film:

[0018] The produced film is fed into the corona equipment with a corona power of 4-5kW. After corona treatment, the surface tension of the film reaches 50-60mN / m.

[0019] The present invention has the following advantages:

[0020] 1. The PLA / PBAT blend system makes the finished material fully biodegradable, which helps to improve the environmental problems caused by plastic pollution;

[0021] 2. By adjusting the ratio of PLA and PBAT, the blended material has excellent mechanical properties. By adding chain extenders to increase the molecular weight of PLA and PBAT, their physical properties and hydrolysis resistance are improved. By adding calcium carbonate, the crystallinity of PLA and PABT is increased, and the stability of the blend system is improved.

[0022] 3. By adding tetramethyldisiloxane and hexachlorocyclotriphosphazene to PLA / PBAT, a composite silicon-phosphorus flame retardant system improves the flame retardancy of the material while overcoming the limitations of conventional flame retardants. Phosphorus-based flame retardants are highly efficient and can be halogen-free. Their plasticizing properties improve the fluidity of plastic molding processes. They are also less corrosive during combustion, hindering re-ignition. However, phosphorus-based flame retardants also have drawbacks when used alone, such as high volatility, poor heat resistance, poor compatibility, and the generation of dripping during combustion.

[0023] Silicone flame retardants are highly efficient, safe, melt-proof, and smoke-proof halogen-free flame retardants that can effectively improve the processing performance, mechanical properties, and heat resistance of PLA. They are also one of the best modifiers. However, when used alone, silicone flame retardants have poor flame retardant effects, which to some extent limits their application in flame-retarding PLA and PBAT.

[0024] The silicon-phosphorus composite system adopted in the present invention can combine the advantages of silicon-based flame retardants and phosphorus-based flame retardants. Tetramethyldisiloxane is used as a silicon source and hexachlorocyclotriphosphazene is used as a phosphorus source. The desired silicon-phosphorus composite flame retardant is obtained through a stirring-filtration-drying method, which can achieve excellent flame retardant effect.

[0025] 4. By adding superconductive carbon black as the main conductive function and wollastonite as a filler to PLA / PBAT, a modified system that can conduct charges and thus play an anti-static role is built. The anti-static principle of the present invention is to add superconductive carbon black as a conductive filler to modify PLA / PBAT. Superconductive carbon black can reduce the percolation threshold of the material and form a conductive path within the material, thereby playing a role in conducting charges. Wollastonite, as a filler between superconductive carbon black and PLA / PBAT system, can not only improve the stacking density of the system; it can also act as a nucleus in the resin crystallization process, increase the crystallinity of the resin, and thus improve the mechanical properties of the system. Compared with traditional additive antistatic agents, the superconductive carbon black antistatic agent of the present invention is added in small amounts, and only needs to be added within 3%. To achieve a good antistatic effect, the superconductive carbon black is surface-activated with acidic potassium permanganate, creating pores on its surface and thus acquiring active groups, thereby improving compatibility with polymers and facilitating melt blending with PLA / PBAT. The superconductive carbon black is then subjected to a secondary oxidation treatment with hydrogen peroxide, further increasing its specific surface area and compacted density. This double oxidation modification increases the number of nanoscale micropores on the material's surface, improving not only compatibility with polymers but also its ability to conduct charge, thereby enhancing its electrical conductivity. After surface activation, the addition of 3%-5% superconductive carbon black as an antistatic agent has virtually no effect on the mechanical properties of PLA / PBAT.

[0026] 5. By adding POE grafted GMA compatibilizer, the compatibility between PLA / PBAT masterbatch and antistatic system and flame retardant system in the entire blending system is improved, and the processing performance is improved.

[0027] 6. Compared with the conventional melt blending and extrusion method, the present invention adopts a two-stage production step of granulation followed by processing. The PLA / PBAT blended modified material is first granulated. The size, shape and distribution of the particles can be locked by granulation, which can make the material relatively stable. At the same time, after granulation, the particles are relatively smooth and the gaps between the particles are reduced, which can improve the fluidity of the material and facilitate its processing in the screw extruder.

[0028] 7. The corona treatment process is used for the produced film to enhance the surface energy of the film, improve its wettability and hydrophilicity, which is beneficial to surface coating and bonding and other processing. It also improves the adhesion and durability of the film and enhances the film's anti-scratch performance. DETAILED DESCRIPTION

[0029] The embodiments of the present invention are described in detail below.

[0030] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0031] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediary, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0032] Example

[0033] This embodiment adopts the following raw materials to carry out trial production.

[0034] Scientific name Trade name Supplier Polylactic acid (PLA) 4032D NatureWorks, USA Polybutylene adipate terephthalate (PBAT) C1200 Basf, Germany Joncryl chain extender ADR 4468 Basf, Germany Nano calcium carbonate 3000 mesh Shandong Zhongtian Mining Industry Superconductive carbon black (SCCB) EC6000JD Lion Specialty Chemicals, Japan Wollastonite 1200 mesh Shandong Zhongtian Mining Industry Hexachlorocyclotriphosphazene MFCD00006474 Merck Life Science Tetramethyldisiloxane / Jiaxing United Chemical Co., Ltd. Antioxidant IRGOFAS 168 Basf, Germany Slip agent Armoslip E PMC, USA POE grafted GMA compatibilizer W5D Kao Attapulgite Co., Ltd. <![CDATA[高锰酸钾KMnO4]]> / Jiangsu Dongcan Chemical Industry <![CDATA[98%浓硫酸H2SO4]]> / Merck Life Science Concentrated hydrochloric acid HCL / Merck Life Science Silane coupling agent KH550 HZ-BK-1833 Shandong Huachen New Material Co., Ltd.

[0035] The preparation method is as follows:

[0036] 1. Take 75 parts of PLA, 25 parts of PBAT, 1-3 parts of ADR-4468 chain extender, 1-3 parts of antioxidant 168, and 30 parts of nano-calcium carbonate, dry them in an electric blast drying oven at 50°C for 4 hours, then put them into a high-speed color mixer, adjust the speed to 1000rpm, mix and disperse for 2 hours, take them out and add them to a twin-screw extruder, the screw barrel temperatures are: 150°C, 155°C, 155°C, 160°C, 160°C, and the head temperature is 165°C, 165°C; the screw speed is 150r / min, and then cut into PLA / PBAT plastic rice through an air-cooled granulation equipment, place them in an electric blast drying oven and dry them for 2 hours for storage;

[0037] 2. Take 70-80 parts of hexachlorocyclotriphosphazene and 20-25 parts of tetramethyldisiloxane, add 5-10 parts of silane coupling agent KH550 dropwise into a beaker, place in a 60°C water bath and stir for 3 hours. After the reaction is complete, filter with a suction flask, place the filtered precipitate in a 50°C electric blast drying oven and dry for 4 hours to obtain a silicon-phosphorus composite flame retardant;

[0038] 3. Take 3-5 parts of superconductive carbon black and 10-15 parts of potassium permanganate, add 30-40 parts of deionized water, place in a beaker, stir thoroughly with a stirrer for 2 hours, transfer to a three-necked flask, slowly add 50-60 parts of 98% concentrated sulfuric acid, and then reflux in a water bath at 90°C for 2 hours. After natural cooling, filter and wash with concentrated hydrochloric acid to remove the MnO2 generated during the treatment. Then wash with deionized water until it is close to neutral, filter and finally dry in an electric blast drying oven at 100°C for 8 hours to obtain an antistatic agent.

[0039] 4 Take 90-95 parts of PLA / PBAT plastic rice after granulation and cutting in 2.3.1, 1-3 parts of antistatic additive produced in 2.3.2, 1-3 parts of flame retardant produced in 2.3.3, 1-3 parts of lubricant, 3-5 parts of POE grafted GMA compatibilizer, dry them in an electric blast drying oven at 50°C for 4 hours, then put them into a high-speed color mixer, adjust the speed to 1000rpm, mix and disperse for 2 hours, take them out and add them to a twin-screw extruder, the screw and barrel temperatures are: 155°C, 155°C, 160°C, 165°C, 165°C, and the head temperature is 165°C, 165°C; the screw speed is 150r / min, the production speed is 15kg / h, and the finished plastic film with a thickness of about 3.5C is produced.

[0040] The following table shows the mechanical properties test of PLA / PBAT film after adding activated superconductive carbon black.

[0041]

[0042]

[0043] As can be seen from the above table, even if 5% activated superconductive carbon black is added, the mechanical properties of the PLA / PBAT film are almost unchanged.

[0044] While the present invention has been described in detail above, the present invention is not limited to the aforementioned embodiments. Various modifications are possible within the scope of knowledge of those skilled in the art without departing from the spirit of the present invention. Numerous other changes and modifications that do not depart from the spirit and scope of the present invention should be considered within the scope of protection of the present invention.

[0045] In the description of this specification, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0046] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for preparing a flame retardant and antistatic degradable film, characterized in that: The method comprises the following steps: 1) preparing an antistatic agent; Take 3-5 parts of superconductive carbon black EC6000JD, 10-15 parts of potassium permanganate, add 30-40 parts of deionized water, place in a beaker, use a stirrer to fully stir for 2 hours, then transfer to a three-necked flask, then slowly add 50-60 parts of 98% concentrated sulfuric acid, then reflux at a constant temperature of 90°C in a water bath for 2 hours, filter after natural cooling, and wash with concentrated hydrochloric acid to remove MnO2 generated during the treatment process, and wash with deionized water until neutral; then take 30-40 parts of 30% concentration hydrogen peroxide and add it to the three-necked flask, condense and reflux at a constant temperature of 60°C for 4 hours, and then wash with deionized water until nearly neutral; then filter, and finally dry in an electric blast drying oven at 100°C for 8 hours to obtain an antistatic agent; 2) preparing a silicon-phosphorus composite flame retardant; Take 70-80 parts of hexachlorocyclotriphosphazene MFCD00006474 and 20-25 parts of tetramethyldisiloxane, add 5-10 parts of silane coupling agent KH550 dropwise into a beaker, place in a 60°C water bath and stir for 3 hours. After the reaction is complete, filter with a suction flask, and place the filtered precipitate in a 50°C electric blast drying oven to dry for 4 hours to obtain a silicon-phosphorus composite flame retardant; 3) Preparation of PLA / PBAT plastic rice; Take 50-75 parts of 4032D PLA, 25 parts of C1200 PBAT, 1-3 parts of ADR-4468 chain extender, 1-3 parts of antioxidant IRGOPAS 168, and 20-30 parts of nano-calcium carbonate and dry them; add the above raw materials after mixing and dispersing, extrude and granulate them in a twin-screw extruder with air cooling; 4) Preparation of thin films; Take 90-95 parts of granulated and cut PLA / PBAT plastic rice, 1-3 parts of antistatic additive, 1-3 parts of flame retardant, 1-3 parts of lubricant, 3-5 parts of POE grafted GMA compatibilizer W5D, and dry; The above raw materials were mixed and dispersed and then added into a twin-screw extruder; the screw speed was 150r / min and the production speed was 15kg / h to produce a finished plastic film; 5) Corona treatment of film: The produced film is fed into the corona equipment with a corona power of 4-5kW. After corona treatment, the surface tension of the film reaches 50-60mN / m.

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