High-transparency and high-flame-retardancy antistatic TPU (thermoplastic polyurethane) film and preparation method thereof

Abstract

The invention provides a high-transparency and high-flame-retardancy antistatic TPU (thermoplastic polyurethane) film and a preparation method thereof. The TPU composite material comprises the following components in parts by weight: 100 parts of TPU master batch, 1-2.5 parts of an antistatic agent, 20-25 parts of a flame retardant, 2-3 parts of an antioxidant and 0.5-1.5 parts of a dispersing agent. The invention further relates to a preparation method of the antistatic TPU film, the antistatic master batch and the flame-retardant master batch are manufactured through polymer modification, then a single-screw extruder is adopted to extrude a cast film according to the polymer blending principle, and compared with a traditional hot melting mode, the method is more convenient, continuous production can be guaranteed, and production loss is reduced; the resistivity of the antistatic TPU film prepared by the method disclosed by the invention can be stabilized by 7 power for a long time, and the resistivity is greatly improved compared with that of a traditional antistatic TPU film.

Description

Technical Field

[0001] This invention relates to the field of polymer materials; and more particularly to a highly transparent, highly flame-retardant antistatic TPU film and its preparation method. Background Technology

[0002] TPU is a polymer material synthesized by the reaction of diisocyanate molecules such as diphenylmethane diisocyanate (MDI) or toluene diisocyanate (TDI) with macromolecular polyols and low-molecular-weight polyols (chain extenders). Its molecular structure consists of alternating rigid blocks obtained from the reaction of MDI or TDI with chain extenders and flexible segments obtained from the reaction of MDI or TDI with macromolecular polyols. TPU possesses excellent high tensile strength, high tensile strength, toughness, and aging resistance, making it a mature and environmentally friendly material. Currently, TPU is widely used in medical and health, electronics, industry, and sports, among other fields. TPU film is an important application form of TPU material, and its application has become increasingly widespread in recent years with the development and progress of high technology.

[0003] Currently, antistatic TPU film is a hot topic, but existing antistatic films either have yellowing issues or fail to meet the requirement of long-term stability. In this scenario, meeting the antistatic requirement is to prevent fires caused by sparks from static electricity; to enhance protection, flame-retardant properties are added on top of the original antistatic properties; this double protection ensures a reduced chance of combustion during product use.

[0004] Existing processing techniques, such as those described in patents CN202121676649.7 and CN201611090332.9, achieve antistatic properties through a three-layer film applied via hot-melt bonding. This method is complex and difficult to implement. In terms of product performance, while the product manufactured using patent CN202510362919.3 meets the requirements for flame retardancy and antistatic properties, it does not describe the standards and performance that flame retardancy can achieve, nor does it demonstrate that the resistivity value can guarantee long-term stability. Summary of the Invention

[0005] The purpose of this invention is to provide a highly transparent and highly flame-retardant antistatic TPU film and its preparation method.

[0006] This invention is achieved through the following technical solution: This invention relates to a highly transparent and highly flame-retardant antistatic TPU film, comprising the following components by weight: 100 parts TPU masterbatch, 1-2.5 parts antistatic agent, 20-25 parts flame retardant, 2-3 parts antioxidant, and 0.5-1.5 parts dispersant; in, The TPU masterbatch has a Shore A hardness of 80A-90A; The antistatic agent is a nonionic antistatic agent; The flame retardant is a nitrogen-based flame retardant; The antioxidants are phosphites; The dispersant is a metallic wax.

[0007] The functions of each component in this invention are as follows: The role of TPU masterbatch is: TPU masterbatch is the substrate for preparing antistatic TPU film in this invention. Various additives are added in this invention to modify TPU masterbatch and improve its performance. The function of antistatic agents is to give products antistatic properties, reduce static electricity, increase resistivity, and ensure that products maintain high transparency even with high resistivity. The function of flame retardants is to give products flame retardant properties. Flame retardants with appropriate components can achieve flame retardant performance that meets the required standards.

[0008] The role of antioxidants is to effectively reduce the rate of auto-oxidation of plastic materials and delay the aging and degradation of plastic materials.

[0009] The role of dispersants is to improve the compatibility between components.

[0010] In this invention, the TPU masterbatch, antioxidant, and dispersant work synergistically to significantly improve the processing stability and long-term aging resistance of the material. In addition, the dispersant helps the antioxidant to be evenly distributed in the TPU matrix, enhances its free radical capture efficiency, thereby delaying the oxidative degradation process and improving the film transparency and mechanical properties.

[0011] TPU masterbatch, flame retardant, antistatic agent, and dispersant work synergistically to significantly improve the flame retardant and antistatic properties of the material. In addition, the dispersant helps the flame retardant and antistatic agent to be evenly distributed in the TPU masterbatch, increasing the product's temperature resistance and flame retardant properties, as well as increasing the resistivity value, thus improving the product's flame retardant and resistivity properties.

[0012] Preferably, the TPU masterbatch is 85A polyester masterbatch; the nonionic antistatic agent is tributylmethylammonium bis(trifluoromethanesulfonyl)imide salt; the nitrogen-based flame retardant is cyanurate; the phosphite antioxidant is bis[2-methyl-4,6-diphenol] ethyl phosphite; and the metal wax is calcium stearate.

[0013] This invention also relates to a method for preparing the aforementioned high-transparency, high-flame-retardant antistatic TPU film, comprising the following steps: Step 1, Preparation of antistatic masterbatch: The TPU masterbatch, antistatic agent, antioxidant and dispersant are granulated in a weight ratio of 100:(1~2.25):(2~3):(0.5~1) to obtain antistatic masterbatch; Step 2, Flame retardant masterbatch preparation: The TPU masterbatch, flame retardant and dispersant are granulated in a weight ratio of 100:(20-25):(0.5-1) to obtain flame retardant masterbatch; Step 3: Place the prepared antistatic masterbatch and flame retardant masterbatch into a dehumidifying dryer and dry at 90°C for 3-4 hours; Step 4: Weigh the dried antistatic masterbatch and flame retardant masterbatch in batches of 10 kg each, put them into a single screw barrel, and adjust the temperature to 80℃ to obtain mixed particles. Step 5: Cast the mixed particles into a film using a casting machine, cool and wind it up, and package it to obtain a finished product of highly transparent and highly flame-retardant antistatic TPU film.

[0014] Preferably, in step 5, the casting machine is a Kingwell GWS92 / 34 single-screw extruder.

[0015] Preferably, in step 5, the temperature of the first zone of the casting machine is 180°C, the temperature of the second zone is 190°C, the temperature of the third zone is 200°C, the temperature of the fourth zone is 190°C, the temperature of the first die is 180°C, the temperature of the second die is 180°C, the temperature of the third die is 180°C, the temperature of the screen changing zone is 190°C, the screw speed is 12 rpm, the temperature of the middle roller is 45°C, and the temperature of the front roller is 55°C.

[0016] The principle of this invention is as follows: First, antistatic masterbatch and flame retardant masterbatch are prepared by polymer modification, and then extrusion casting film is carried out using a single screw extruder based on the principle of polymer blending.

[0017] The present invention has the following advantages: (1) The method of the present invention first prepares antistatic masterbatch and flame retardant masterbatch by polymer modification, and then uses a single screw extruder to extrude and cast film using the principle of polymer blending; compared with the traditional hot melt method, the method of the present invention is more convenient, can ensure continuous production, and reduce production losses; (2) The resistivity of the antistatic TPU film prepared by the method of the present invention can be kept stable at the 7th power for a long time, which is a significant improvement over the resistivity of traditional antistatic TPU films. Detailed Implementation

[0018] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are merely further illustrations of the present invention, but the scope of protection of the present invention is not limited to the following embodiments.

[0019] Examples 1 to 4 relate to a highly transparent and highly flame-retardant antistatic TPU film and its preparation method, including the following steps: The component contents of Examples 1 to 4 are shown in Table 1: Step 1, Antistatic Masterbatch Preparation: TPU masterbatch, antistatic agent, antioxidant and dispersant are granulated in a weight ratio of 100:1:2:0.5 to obtain antistatic masterbatch; Step 2, Flame retardant masterbatch preparation: The TPU masterbatch, flame retardant and dispersant are granulated in a weight ratio of 100:20:0.5 to obtain the flame retardant masterbatch; Step 3: Place the prepared antistatic masterbatch and flame retardant masterbatch into a dehumidifying dryer and dry at 90°C for 3-4 hours; Step 4: Weigh the dried antistatic masterbatch and flame retardant masterbatch in batches of 10 kg each, put them into a single screw barrel, and adjust the temperature to 80℃ to obtain mixed particles. Step 5: Cast the mixed particles into a film using a casting machine, cool and wind it up, and package it to obtain a finished product of highly transparent and highly flame-retardant antistatic TPU film.

[0020] Comparative Examples 1 through 5 all relate to a method for preparing an antistatic TPU film, including the following steps: Step 1: Mix the components in Table 1, granulate them, and then dry them in a dehumidifying dryer at 90°C for 3-4 hours. Step 2: Weigh the dried masterbatch in batches of 10 kg each, place them in a single screw press, and adjust the temperature to 80℃ to obtain mixed particles; Step 3: Cast the mixed particles into a film using a casting machine, cool and wind it up, and package it to obtain a finished antistatic TPU film with high transparency and high flame retardancy.

[0021] Table 1 Unit: Kg Components Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 TPU Masterbatch 100 100 100 100 100 100 100 100 100 Antistatic agent 2.5 1 1 2.5 0.5 0 3 1 1 Flame retardant 20 20 25 25 20 0 25 10 10 antioxidants 3 2.5 3 2 3 0 3 3 3 dispersant 0.5 1 0.5 0.5 0.5 0 0.5 0.5 0.5 In Table 1, the TPU masterbatch for Example 4 and Comparative Example 5 is (Lubrizol BF92), which is the same as the TPU masterbatch (Lubrizol BF85); the nonionic antistatic agent is tributylmethylammonium bis(trifluoromethanesulfonyl)imide salt; the nitrogen-based flame retardant is cyanurate; the phosphite antioxidant is bis[2-methyl-4,6-diphenol] ethyl phosphite; and the metal wax is calcium stearate.

[0022] Flame retardant electrostatic performance tests are shown in Table 2: Table 2 Test Project unit Test Standards Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 thickness mm ASTM D3767-2020 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 color / Visual inspection True Colors True Colors True Colors True Colors True Colors True Colors True Colors True Colors True Colors Film surface effect / Visual inspection Fully transparent Fully transparent Fully transparent Fully transparent Fully transparent Fully transparent Fully transparent Fully transparent Fully transparent Light transmittance % ASTM D1003-2021 91.64 93.3 93.4 95.32 85.62 92.6 80.56 90.59 94.5 resistivity value Ω ASTM D257-2007 1.11*10 6 ]]> 1.32*10 6 ]]> 1.5*10 6 ]]> <![CDATA[1.28*10 7 ]]> <![CDATA[1.25*10 7 ]]> <![CDATA[1.25*10 9 ]]> <![CDATA[2.8*10 7 ]]> <![CDATA[2.7*10 7 ]]> <![CDATA[1.46*10 7 ]]> Resistivity value after 7 days of aging with dual 85 Ω ASTM D257-2007 <![CDATA[3.86*10 7 ]]> <![CDATA[3.2*10 7 ]]> <![CDATA[4.5*10 7 ]]> <![CDATA[3.78*10 7 ]]> <![CDATA[1.26*10 11 ]]> <![CDATA[4.50*10 9 ]]> <![CDATA[2.8*10 11 ]]> <![CDATA[5.6*10 7 ]]> <![CDATA[2.22*10 7 ]]> Flame retardant properties / UL-94 V-0 V-0 V-0 V-0 V-2 V-2 V-2 V-2 V-2 As shown in Table 2, compared to Comparative Examples 1 and 3, Examples 1, 2, 3, and 4 exhibit higher transparency while maintaining long-term stability at or above the 7th power. Compared to Comparative Example 2, Examples 1, 2, 3, and 4 demonstrate more stable long-term resistivity values ​​while maintaining high transparency. Compared to Comparative Examples 4 and 5, Examples 1, 2, 3, and 4 meet the V-0 performance of the UL-94 standard while maintaining long-term resistivity stability at the 7th power. UL-94, short for "Test for Flammability of Plastic Materials for Parts in Devices and Appliances," primarily tests the flame retardancy of plastic materials under controlled flame conditions. It applies to non-metallic materials such as electronic devices and electrical parts, but does not cover plastics used in construction or decoration. This standard measures the self-extinguishing ability, dripping risk, and flame spread rate of materials through laboratory simulations of heat source exposure scenarios, ensuring the fire safety of products in real-world use. UL 94 defines 12 fire resistance ratings, categorized by material type and test protocol: General ratings: HB (horizontal burning), V-0 / V-1 / V-2 (vertical burning), 5VA / 5VB (high-intensity flame test). The V-0 rating requires self-extinguishing within 10 seconds after the flame is removed and that molten droplets do not ignite the cotton below. The 5VA / 5VB rating requires withstanding five 125mm flame impacts without structural damage. The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A highly transparent and highly flame-retardant antistatic TPU film, characterized in that, By weight, it comprises the following components: 100 parts TPU masterbatch, 1 to 2.5 parts antistatic agent, 20 to 25 parts flame retardant, 2 to 3 parts antioxidant, and 0.5 to 1.5 parts dispersant; in, The TPU masterbatch has a Shore A hardness of 80A-90A; The antistatic agent is a nonionic antistatic agent; The flame retardant is a nitrogen-based flame retardant; The antioxidants are phosphites; The dispersant is a metallic wax.

2. The high-transparency, high-flame-retardant antistatic TPU film as described in claim 1, characterized in that, The TPU masterbatch is 85A polyester masterbatch; the nonionic antistatic agent is tributylmethylammonium bis(trifluoromethanesulfonyl)imide salt; the nitrogen-based flame retardant is cyanurate; the phosphite antioxidant is bis[2-methyl-4,6-diphenol] ethyl phosphite; and the metal wax is calcium stearate.

3. A method for preparing a high-transparency, high-flame-retardant antistatic TPU film as described in claim 1, characterized in that, Includes the following steps: Step 1, Preparation of antistatic masterbatch: The TPU masterbatch, antistatic agent, antioxidant and dispersant are granulated in a weight ratio of 100:(1~2.25):(2~3):(0.5~1) to obtain antistatic masterbatch; Step 2, Flame retardant masterbatch preparation: The TPU masterbatch, flame retardant, and dispersant are granulated at a weight ratio of 100:(20-25):(0.5-1) to obtain flame retardant masterbatch; Step 3: Place the prepared antistatic masterbatch and flame retardant masterbatch into a dehumidifying dryer and dry at 90°C for 3-4 hours; Step 4: Weigh the dried antistatic masterbatch and flame retardant masterbatch in batches of 10 kg each, put them into a single screw barrel, and adjust the temperature to 80℃ to obtain mixed particles. Step 5: Cast the mixed particles into a film using a casting machine, cool and wind it up, and package it to obtain a finished antistatic TPU film with high transparency and high flame retardancy.

4. The method for preparing the high-transparency, high-flame-retardant antistatic TPU film as described in claim 3, characterized in that, In step 5, the casting machine is a single-screw extruder, namely a Gemwell GWS92 / 34.

5. The method for preparing the high-transparency, high-flame-retardant antistatic TPU film as described in claim 3, characterized in that, In step 5, the temperature of the first zone of the casting machine is 180℃, the temperature of the second zone is 190℃, the temperature of the third zone is 200℃, the temperature of the fourth zone is 190℃, the temperature of the first die is 180℃, the temperature of the second die is 180℃, the temperature of the third die is 180℃, the temperature of the screen changing zone is 190℃, the screw speed is 12rpm, the temperature of the middle roller is 45℃, and the temperature of the front roller is 55℃.