A polishing and grinding TPU composite film and a preparation method thereof

Abstract

The application relates to the technical field of TPU composite film processing, in particular to a TPU composite film for polishing and grinding and a preparation method thereof, which sequentially comprises a substrate layer, a polyurethane coating layer, a TPU film layer and a protective release layer, and sequentially comprises a substrate layer, a polyurethane coating layer, a TPU film layer and a protective release layer, wherein the TPU film layer is prepared from TPU particles; the TPU composite film prepared in the application can provide good polishing effect, easy operation, low cost, environmental protection and no pollution and the like.

Description

Technical Field

[0001] This application relates to the field of TPU composite film processing technology, and more specifically, to a TPU composite film for polishing and grinding and a method for preparing the same. Background Technology

[0002] Mobile phone frames require grinding and polishing during manufacturing to enhance their gloss and smoothness, meeting both aesthetic and durability requirements. Currently, diamond polishing films, nano-polishing films, and chemical polishing films are primarily used. Among them, diamond polishing film uses diamond particles as abrasives, which have extremely high hardness and strong wear resistance. It can efficiently remove imperfections and unevenness from the surface of the phone frame, with high polishing efficiency and high gloss and flatness, resulting in a good visual effect. However, diamond polishing film is relatively expensive, and precise control of polishing pressure and speed is required to avoid excessive wear or damage to the phone frame, which requires a high level of skill from the operator. Nano polishing film uses nano-level abrasive particles for polishing, achieving extremely high polishing precision and making the surface of the phone frame smoother and more delicate. However, nano polishing film is also relatively expensive, and professional polishing equipment and operating skills are required to ensure the polishing effect. Chemical polishing film removes oxides and stains from the surface of the phone frame through chemical reaction, achieving a polishing effect. The polished surface has high gloss and is relatively simple to use, requiring no complicated equipment or operation. However, the effect of chemical polishing may be affected by the chemical reaction conditions, making it difficult to guarantee polishing consistency. Furthermore, chemical polishing film has poor adaptability and may not achieve the expected polishing effect when polishing phone frames of different materials.

[0003] In summary, there is no existing polishing film that is easy to operate, has good polishing effect, is low-cost, and pollution-free. Summary of the Invention

[0004] To address the issue that existing mobile phone frame polishing films cannot simultaneously achieve ease of operation, good polishing effect, low cost, and no pollution, this application provides a TPU composite film for polishing and grinding, and its preparation method.

[0005] In a first aspect, this application provides a TPU composite film for polishing and grinding, which adopts the following technical solution: a TPU composite film for polishing and grinding, comprising a substrate layer, a polyurethane coating, a TPU film layer and a protective release layer, wherein the TPU film layer is prepared from TPU particles.

[0006] By adopting the above technical solution, the prepared TPU composite film can provide advantages such as good polishing effect, easy operation, low cost and environmental protection without pollution.

[0007] Preferably, the TPU film layer is prepared from the following raw materials in parts by weight: TPU 95-98 parts 2-8 parts lubricant The lubricant is composed of polyoxypropylene polyoxyethylene glycerol ether, magnesium stearate and fatty acid amide.

[0008] By adopting the above technical solution, the prepared TPU composite film can provide advantages such as good polishing effect, easy operation, low cost and environmental protection without pollution.

[0009] The TPU film layer in this application is used for polishing because TPU has excellent wear resistance. Using TPU as the main component improves the wear resistance of the TPU film layer, allowing the composite film to maintain a smooth surface and resist wear for extended periods during polishing. Simultaneously, TPU's good elasticity allows the composite film to quickly recover its deformation under external force, thus maintaining a stable polishing effect. Furthermore, TPU exhibits good stability against various chemical substances and is not easily corroded by acids, alkalis, etc., ensuring the composite film is suitable for various polishing fluids and can be used long-term in complex environments. By using a substrate layer to support the TPU film layer, deformation or damage to the composite film during polishing is prevented, thus maintaining a consistent polishing effect and facilitating polishing of the TPU film layer. A polyurethane coating is used to fix the substrate layer and the TPU layer, preventing their separation.

[0010] The lubricant in the TPU composite film is composed of polyoxypropylene polyoxyethylene glycerol ether, magnesium stearate, and fatty acid amide. It can be evenly distributed on the polishing surface, providing a stable lubrication effect, thus ensuring polishing consistency. Simultaneously, it reduces frictional resistance during polishing, making polishing easier and improving efficiency. Polyoxypropylene polyoxyethylene glycerol ether has good lubricity and dispersibility, reducing the coefficient of friction between the TPU film and the polished surface, minimizing heat and wear. Magnesium stearate has lubricating and release properties, forming a lubricating film between the TPU film and the polished surface, further reducing friction and helping to prevent film adhesion during polishing. Fatty acid amide has excellent lubricity and anti-wear properties, enhancing the wear resistance of the TPU film while providing additional lubrication, making the polishing process smoother.

[0011] The TPU composite film design of this application does not rely on complex polishing equipment or highly specialized operating skills. Its softness and elasticity make the polishing process smoother, reducing the need for precise control of polishing pressure and speed. In use, simply connect the substrate layer to the polishing wheel. If using Velcro, adhere the rough side of the Velcro to the substrate layer, attach the hook side of the Velcro to the polishing wheel, and then attach the rough and hook sides together to complete the assembly of the TPU composite film for polishing and grinding. This is convenient and quick, requiring no specific equipment. In use, spray polishing liquid onto the TPU film layer, and then use the TPU film layer to polish the phone frame. The TPU composite film has strong adaptability to different materials, making it suitable for various phone frame materials and improving polishing adaptability.

[0012] Compared to diamond polishing films and nano-polishing films, the TPU composite film used in this application has a lower cost.

[0013] Preferably, the weight ratio of the polyoxypropylene polyoxyethylene glycerol ether, the magnesium stearate, and the fatty acid amide is 3:(5-6):1.

[0014] By adopting the above technical solution and optimizing the dosage of polyoxypropylene polyoxyethylene glycerol ether, magnesium stearate and fatty acid amide, the polishing efficiency of mobile phone frame is further improved, the consistency and uniformity of polishing are enhanced, and the film is made applicable to a variety of mobile phone frame materials, thus improving the adaptability of polishing.

[0015] Preferably, the TPU film layer further includes 5-10 parts by weight of nano-solid filler.

[0016] By adopting the above technical solutions, the polishing effect of TPU composite film when polishing mobile phone frames can be further improved. The nano-solid filler has extremely high hardness and wear resistance, which can improve the hardness and wear resistance of the TPU film layer, allowing the TPU composite film to better resist wear during polishing and extend its service life. At the same time, the tiny size of the nano-solid filler allows it to fill the tiny pores in the TPU film layer, making the film surface smoother, which helps to improve polishing precision, resulting in a smoother and more delicate surface on the polished mobile phone frame.

[0017] Preferably, the nano solid filler is composed of nano silicon carbide, nano silicon nitride and nano magnesium silicate in a weight ratio of (4-5):2:(3-6).

[0018] By adopting the above technical solutions and optimizing the type and amount of nano-solid fillers, the efficiency and precision of TPU composite films in polishing mobile phone frames are further improved. Simultaneously, the hardness and wear resistance of the TPU film layer are increased, making it more durable, scratch-resistant, and extending the service life of the TPU film. Nano-silicon carbide and nano-silicon nitride both possess high hardness and high wear resistance, enabling them to quickly remove imperfections and unevenness from the surface of the mobile phone frame, thereby improving polishing efficiency. The addition of nano-magnesium silicate further enhances the dispersibility and stability of the fillers, ensuring the uniformity and consistency of the polishing process.

[0019] Preferably, the polyurethane coating is obtained by applying polyurethane adhesive to the surface of the substrate layer, wherein the polyurethane adhesive is prepared from the following raw materials in parts by weight: 20-25 parts of polyether multi-component 15-20 parts of polyester polyol 10-15 parts of diphenylmethane diisocyanate 1-2 parts of curing agent Chain extender 0.8-1.2 parts 0.5-1 part catalyst 1-2 parts of surfactant 30-40 parts organic solvent 5-9 parts of modifier The modifier is composed of epoxy resin, organic sulfonate and hydroxyethyl cellulose.

[0020] By adopting the above technical solution, a stable connection between the substrate layer and the TPU film layer is achieved, ensuring that the TPU layer and the substrate layer do not separate during the polishing process, thereby improving the polishing effect and efficiency. When the materials used for the substrate layer and the TPU film layer are different, resulting in significant differences in surface energy, polarity, or chemical composition, the adhesion between them may weaken, leading to unstable bonding. In this application, the polyurethane prepared using the above formulation exhibits excellent wettability, allowing it to fully penetrate the micropores of the substrate layer and the TPU layer, forming a tight adhesive layer and improving the connection stability between the substrate layer and the TPU layer.

[0021] In this application, a polyurethane prepolymer is generated by combining polyether polyol, polyester polyol, diphenylmethane diisocyanate, and a catalyst. This results in a polyurethane coating that possesses both sufficient flexibility and excellent adhesion properties, enabling it to bond tightly to the substrate layer and the TPU film layer. Surfactants reduce the surface tension between the polyurethane adhesive and the substrate and TPU film layers, promoting wetting and spreading of the adhesive, thus increasing the contact area between the coating and the substrate and TPU film layers and improving adhesion. Organic solvents dilute the polyurethane adhesive, reducing its viscosity and facilitating coating and processing.

[0022] During polishing, TPU films generate heat due to friction, which reduces the adhesion between the substrate layer and the TPU layer, affecting the polishing effect and significantly shortening their lifespan. To address this, this application adds epoxy resin to further improve the heat resistance of the polyurethane adhesive, while also enhancing its adhesive properties. Hydroxyethyl cellulose has excellent thickening and tackifying effects, increasing the viscosity of the polyurethane adhesive and allowing it to penetrate more easily into the micropores of the substrate and TPU film, forming a tight bond. In other words, the synergistic effect of epoxy resin and hydroxyethyl cellulose improves the adhesion of the polyurethane adhesive, enabling stable bonding on various substrates and TPU films. Organic sulfonates improve the wettability and dispersibility of the polyurethane adhesive, contributing to the formation of a uniform coating on the substrate.

[0023] Preferably, the polyurethane adhesive is prepared by the following method: A: Vacuum dry polyether polyol and polyester polyol at 100-110℃, then cool down to 65-75℃, add diphenylmethane diisocyanate and then add catalyst dropwise, heat up to 90-95℃ and react for 2-4 hours, add chain extender and react for 1-2 hours, cool down to 20-30℃ to obtain polyurethane prepolymer. B: Mix the organic solvent and modifier, then add the curing agent, surfactant and polyurethane reactant, stir and mix to obtain polyurethane adhesive.

[0024] By employing the above technical solution, the polyether polyol, polyester polyol, diphenylmethane diisocyanate, and catalyst are fully reacted to form a polyurethane prepolymer with good adhesion. Vacuum drying and temperature control of the polyether polyol and polyester polyol effectively avoid the influence of side reactions and impurities, improving the stability of the adhesive. Mixing the organic solvent and modifier ensures the uniform dispersion of the modifier in the solvent. Stirring and mixing ensures the uniform dispersion and full reaction of all components in the solvent, forming a stable and high-performance polyurethane adhesive.

[0025] Preferably, the weight ratio of the epoxy resin, the organic sulfonate, and the hydroxyethyl cellulose is 4:(0.5-0.8):2.

[0026] By adopting the above technical solution and optimizing the dosage of epoxy resin, organic sulfonate and hydroxyethyl cellulose, the heat resistance, adhesion and wettability of polyurethane adhesive are further improved, making it easier to coat and bond.

[0027] Preferably, the thickness of the substrate layer is 0.01-0.2 mm, the thickness of the polyurethane coating is 0.001-0.06 mm, and the thickness of the TPU is 0.01-0.2 mm.

[0028] By adopting the above technical solutions and optimizing the thickness of the substrate layer, polyurethane coating, and TPU, the uniform transmission of polishing force and the uniformity of polishing effect are ensured during the polishing process. This helps to reduce defects such as scratches and pits generated during polishing, and improves the surface gloss and smoothness after polishing. The thicker substrate layer and appropriate amount of polyurethane coating provide good protection and support, making the TPU composite film less prone to wear or damage during polishing, extending the service life of the polishing film, and reducing replacement frequency and cost.

[0029] Preferably, the substrate layer is one of a PET substrate layer, a PP substrate layer, a PC substrate layer, or a PBT substrate layer.

[0030] By adopting the above technical solutions, the types of substrate layers are optimized, and the durability and support of the substrate layers are improved, enabling them to withstand friction and wear during the polishing process. Furthermore, the aforementioned substrate layers have broad adaptability and can be applied to the polishing needs of mobile phone frames of different materials, shapes, and sizes.

[0031] Secondly, this application provides a method for preparing a TPU composite film for polishing and grinding, using the following technical solution: A method for preparing a TPU composite film for polishing and grinding includes the following preparation steps: S1. Apply polyurethane adhesive to the surface of the substrate layer and cure it to form a polyurethane coating. S2. Mix TPU and lubricant to obtain a mixture, then feed it into a screw extruder to melt it. The molten mixture flows through a die to the surface of the polyurethane coating, cools it, and then attach a release protective film to the surface of the TPU layer to obtain a TPU composite film for polishing and grinding.

[0032] By employing the above technical solution, polyurethane adhesive is coated onto the surface of the substrate layer and cured, quickly forming a uniform and dense polyurethane coating. This not only improves the adhesive strength between the substrate layer and the TPU layer but also enhances the overall structural stability of the composite film. After mixing TPU and lubricant, the mixture is melted and extruded using a screw extruder. The molten mixture flows through a die to the surface of the polyurethane coating, achieving uniform distribution and tight adhesion of the TPU layer, improving the molding efficiency of the TPU layer, and ensuring the smoothness of the composite film surface. Applying a release film to the TPU layer surface effectively prevents the composite film from being contaminated or damaged during subsequent processing or storage.

[0033] In summary, this application has the following beneficial effects: 1. The TPU composite film in this application combines the stability of the substrate layer, the adhesion of the polyurethane coating, and the wear resistance of the TPU film layer, ensuring the high efficiency and durability of the TPU composite film during polishing and grinding. The TPU film layer, with TPU as its main component, possesses excellent wear resistance, allowing the composite film to maintain a smooth surface and resist wear for extended periods during polishing and grinding. Simultaneously, the good elasticity of TPU material allows the composite film to quickly recover its deformation under external force, thus maintaining a stable polishing and grinding effect. By using a lubricant composed of polyoxypropylene polyoxyethylene glycerol ether, magnesium stearate, and fatty acid amide, the coefficient of friction between the composite film and the polishing and grinding surface can be reduced, thereby reducing wear and improving polishing and grinding efficiency. Detailed Implementation

[0034] Preparation Example The epoxy resin was purchased from Anhui Xinyuan Technology Co., Ltd., model number XY128L.

[0035] The polyether polyol was purchased from Jiangsu Leien Environmental Protection Technology Co., Ltd., model number MN-700.

[0036] The polyester polyol was purchased from Shanghai Hongzhuang Chemical Technology Co., Ltd., and its model number is C10H20O6.

[0037] Preparation Example 1 A polyurethane adhesive is prepared by the following method: A: 200g of polyether polyol and 150g of polyester polyol were vacuum dried at 100℃, then cooled to 65℃, 100g of diphenylmethane diisocyanate was added, and 5g of catalyst (dibutyltin dilaurate) was added dropwise. The mixture was heated to 90℃ and reacted for 2h. Then, 8g of chain extender (neopentyl glycol) was added and reacted for 1h. The mixture was then cooled to 20℃ to obtain the polyurethane reactant. B: Mix 300g of organic solvent (ethyl acetate) and 50g of modifier, then add 10g of curing agent (triethylenetetramine), 10g of surfactant (dodecyl ammonium bromide) and polyurethane reactants, stir and mix to obtain polyurethane adhesive.

[0038] The modifier is composed of epoxy resin, organic sulfonate (sodium lignosulfonate) and hydroxyethyl cellulose in a weight ratio of 4:0.5:2.

[0039] The difference between Preparation Examples 2-3 and Preparation Example 1 lies in the types and amounts of raw materials used to prepare the polyurethane adhesive, as well as the experimental parameters. The specific differences are shown in Table 1. Table 1. Raw material types, dosages, and experimental parameters for preparing polyurethane adhesives in Examples 1-3. In Preparation Example 2, the modifier was composed of epoxy resin, organic sulfonate (sodium p-aminobenzenesulfonate), and hydroxyethyl cellulose in a weight ratio of 4:0.6:2.

[0040] In Preparation Example 3, the modifier was composed of epoxy resin, organic sulfonate (sodium pyridine p-toluenesulfonate), and hydroxyethyl cellulose in a weight ratio of 4:0.8:2.

[0041] Preparation Example 4 A polyurethane adhesive, the difference between this preparation example and preparation example 1 is that the weight ratio of epoxy resin, organic sulfonate (sodium lignosulfonate) and hydroxyethyl cellulose is 2:0.5:2.

[0042] Preparation Example 5 A polyurethane adhesive, the difference between this preparation example and preparation example 1 is that the weight ratio of epoxy resin, organic sulfonate (sodium lignosulfonate) and hydroxyethyl cellulose is 2:0.5:4.

[0043] Preparation Example Preparation of Comparative Example 1 A polyurethane adhesive, the difference between this comparative example and preparation example 1 is that the modifier is composed of epoxy resin and organic sulfonate in a weight ratio of 4:0.5.

[0044] Preparation of Comparative Example 2 A polyurethane adhesive, the difference between this comparative example and preparation example 1 is that the modifier is composed of epoxy resin and hydroxyethyl cellulose in a weight ratio of 4:2.

[0045] Preparation of Comparative Example 3 A polyurethane adhesive, the difference between this comparative preparation and Preparation Example 1 is that the modifier is composed of organic sulfonate and hydroxyethyl cellulose in a weight ratio of 0.5:2.

[0046] Preparation of Comparative Example 4 A polyurethane adhesive, the difference between this comparative example and preparation example 1 is that an acrylic resin is used instead of a modifier.

[0047] The acrylic resin was purchased from Shandong Huling New Materials Co., Ltd., model number PT-2060A. Example

[0048] The PET substrate layer was purchased from Liheng New Material Technology (Guangdong) Co., Ltd., model number L-6100.

[0049] The TPU was purchased from Dongguan Zhenpin New Materials Co., Ltd., under the brand name BASF (Germany) and grade 1190A.

[0050] Example 1 A TPU composite film for polishing and grinding is prepared by the following method: S1. Apply polyurethane adhesive to the surface of the substrate layer (PET substrate layer), with a wet coating weight of 10g / m². 2 It cures and forms a polyurethane coating; S2. Mix 990g of TPU to obtain a mixture, then add it to a screw extruder to melt it. The molten mixture flows through a die to the surface of the polyurethane coating, cools it, and then attach a release protective film to the surface of the TPU layer to obtain a TPU composite film for polishing and grinding.

[0051] Example 2 A TPU composite film for polishing and grinding is prepared by the following method: S1. Apply polyurethane adhesive to the surface of the substrate layer (PET substrate layer), with a wet coating weight of 10g / m². 2 It cures and forms a polyurethane coating; S2. Mix 950g of TPU and 40g of lubricant to obtain a mixture, then add it to a screw extruder to melt it. The molten mixture flows through a die to the surface of the polyurethane coating, cools it, and then attach a release protective film to the surface of the TPU layer to obtain a TPU composite film for polishing and grinding.

[0052] The lubricant is composed of polyoxypropylene polyoxyethylene glycerol ether, magnesium stearate and fatty acid amide in a weight ratio of 3:5:1.

[0053] The thickness of the substrate layer is 0.01 mm, the thickness of the polyurethane coating is 0.001 mm, and the thickness of the TPU is 0.01 mm.

[0054] The difference between Examples 3-4 and Example 2 lies in the types and amounts of raw materials used to prepare the TPU composite film for polishing and grinding, as well as the experimental parameters. Specific differences are shown in Table 2. Table 2. Raw material types, dosages, and experimental parameters for the preparation of TPU composite films for polishing and grinding in Examples 2-4. In Example 3, the lubricant was composed of polyoxypropylene polyoxyethylene glycerol ether, magnesium stearate, and fatty acid amide in a weight ratio of 3:5.5:1. The thickness of the substrate layer was 0.1 mm, the thickness of the polyurethane coating was 0.03 mm, and the thickness of the TPU was 0.1 mm.

[0055] In Example 4, the lubricant was composed of polyoxypropylene polyoxyethylene glycerol ether, magnesium stearate, and fatty acid amide in a weight ratio of 3:6:1. The thickness of the substrate layer was 0.2 mm, the thickness of the polyurethane coating was 0.06 mm, and the thickness of the TPU was 0.2 mm.

[0056] Example 5 A TPU composite film for polishing and grinding, the difference between this embodiment and embodiment 1 is that: in step S2, 950g of TPU, 40g of lubricant and 50g of nano solid filler (nano silicon carbide) are mixed.

[0057] Example 6 A TPU composite film for polishing and grinding, the difference between this embodiment and embodiment 1 is that: in step S2, 950g of TPU, 40g of lubricant and 100g of nano solid filler (nano silicon carbide) are mixed.

[0058] Example 7 A TPU composite film for polishing and grinding, the difference between this embodiment and embodiment 4 is that the nano solid filler is composed of nano silicon carbide, nano silicon nitride and nano magnesium silicate in a weight ratio of 4:2:3.

[0059] Example 8 A TPU composite film for polishing and grinding, the difference between this embodiment and embodiment 4 is that the nano solid filler is composed of nano silicon carbide, nano silicon nitride and nano magnesium silicate in a weight ratio of 5:2:6.

[0060] Example 9 A TPU composite film for polishing and grinding, the difference between this embodiment and Example 1 is that the polyurethane adhesive is derived from Preparation Example 4.

[0061] Example 10 A TPU composite film for polishing and grinding, the difference between this embodiment and Example 4 is that the polyurethane adhesive is derived from Preparation Example 5.

[0062] Example 11 A TPU composite film for polishing and grinding, the difference between this embodiment and Example 4 is that the polyurethane adhesive is derived from Comparative Preparation Example 1.

[0063] Example 12 A TPU composite film for polishing and grinding, the difference between this embodiment and Example 1 is that the polyurethane adhesive is derived from Comparative Preparation Example 2.

[0064] Example 13 A TPU composite film for polishing and grinding, the difference between this embodiment and Example 1 is that the polyurethane adhesive is derived from Comparative Preparation Example 3.

[0065] Example 14 A TPU composite film for polishing and grinding, the difference between this embodiment and Example 1 is that the polyurethane adhesive is derived from Comparative Preparation Example 4.

[0066] Comparative Example Comparative Example 1 A TPU composite film for polishing and grinding, the difference between this embodiment and embodiment 1 is that the first step is omitted, and the TPU layer is directly formed on the surface of the PET substrate in step S2.

[0067] Comparative Example 2 A TPU composite film for polishing and grinding, the difference between this embodiment and embodiment 2 is that the lubricant is composed of polyoxypropylene polyoxyethylene glycerol ether, magnesium stearate and fatty acid amide in a weight ratio of 3:5.

[0068] Comparative Example 3 A TPU composite film for polishing and grinding, the difference between this embodiment and embodiment 2 is that the lubricant is composed of magnesium stearate and fatty acid amide in a weight ratio of 5:1.

[0069] Comparative Example 4 A TPU composite film for polishing and grinding, the difference between this embodiment and embodiment 2 is that the lubricant is composed of polyoxypropylene polyoxyethylene glycerol ether and fatty acid amide in a weight ratio of 3:1.

[0070] Detection methods / test methods Polishing rate test: Polishing experiment was conducted using a UNIPOL-1200S CMP test machine. The TPU composite films used for polishing and grinding in Examples 1-14 and Comparative Examples 1-4 were mounted on the polishing wheel. The polishing fluid used was ultrafine high-purity cerium dioxide polishing fluid (purchased from Zhejiang Manli Nanotechnology Co., Ltd.). The polishing pad diameter was 200 mm, and the polishing sample was an iron sheet with a diameter of 2 inches. The polishing parameters are as follows: polishing pressure 3 psi, polishing speed 110 rpm, polishing fluid flow rate 100 mL / min, and polishing time 10 min.

[0071] The mass of the iron sheet before and after polishing was measured using a METTLER TOLETO precision electronic balance, and the material removal rate, i.e., the polishing rate, was calculated during the polishing process. The material removal rate is defined as the thickness of material removed during polishing per unit time, and the calculation formula is as follows: Polishing rate (nm / min) = (W0-Wi) / (pw*Sw*t)*10 7 In the formula, W0 is the mass of the iron sheet before polishing (g), W i p represents the mass (g) of the polished iron sheet. w Where is the density of the iron sheet (g / cm3), and Sw is the surface area of ​​the iron sheet (cm²). 2 ), where t is the polishing time (min).

[0072] Adaptability test: Polishing samples of glass, plastic, stainless steel, copper-aluminum alloy and iron were prepared respectively. The samples were polished according to the polishing rate test method using the TPU composite film for polishing and grinding prepared in Examples 1-15 and Comparative Examples 1-4 respectively. The smoothness and flatness of the sample surface were observed.

[0073] Adhesion stability test of substrate layer and TPU film layer: Polishing experiment was conducted using UNIPOL-1200S CMP test machine. The TPU composite films used for polishing and grinding in Examples 1-14 and Comparative Examples 1-4 were mounted on the polishing wheel. The polishing fluid used was ultrafine high-purity cerium dioxide polishing fluid (purchased from Zhejiang Manli Nano Technology Co., Ltd.). The polishing pad diameter was 200mm, and the polishing sample was a 2-inch diameter iron sheet. The polishing parameters are as follows: polishing pressure 3 psi, polishing speed 50 rpm, polishing fluid flow rate 100 mL / min.

[0074] Grinding was performed according to the above parameters. After grinding for 5 hours, the TPU composite film used for polishing was immersed in a red solution for 10 minutes every 2 hours. After removal, the presence of red liquid between the substrate layer and the TPU film layer was observed. If red liquid was present, the experiment was stopped, and the time it took for red liquid to appear was recorded (5+2n). The experimental data are shown in Table 3. Table 3. Experimental data of Examples 1-13 and Comparative Examples 1-4 Comparing Example 1 and Comparative Example 1, the polishing rate in Comparative Example 1 was lower than that in Example 1, and red liquid appeared after 9 hours in the adhesion stability test between the substrate layer and the TPU film layer. This indicates that the TPU composite film with a specific structure for polishing and grinding prepared by the process in this application has good polishing effect and structural stability. Comparing Example 2 and Comparative Example 1, the polishing rate in Comparative Example 1 was lower than that in Example 1, and red liquid appeared after 9 hours in the adhesion stability test between the substrate layer and the TPU film layer. This indicates that the TPU composite film with a specific structure for polishing and grinding prepared by the process in this application has good polishing effect and structural stability.

[0075] Compared with Example 2, Comparative Examples 2-3 showed that the polishing rate in Comparative Examples 2-3 was lower than that in Example 1, and red liquid appeared after 19 hours in the adhesion stability test between the substrate layer and the TPU film layer. Comparative Examples 2-3 showed that the surfaces of the glass sheet, the copper-aluminum alloy sheet, and the plastic sheet were not smooth, respectively. This indicates that by preparing a lubricant from polyoxypropylene polyoxyethylene glycerol ether, magnesium stearate, and fatty acid amide, and then participating in the preparation of the TPU film layer, the polishing effect, structural stability, and adaptability of the TPU composite film used for polishing and grinding can be further improved.

[0076] Comparing Examples 2 and 5-6, the polishing rate in Examples 5-6 is higher than that in Example 2, indicating that by adding nano solid fillers, the polishing effect of the TPU composite film used for polishing and grinding can be further improved.

[0077] Comparing Example 5 with Examples 7-8, the polishing rate in Examples 7-8 is higher than that in Example 5, indicating that by optimizing the type and amount of nano solid filler, the polishing effect of the TPU composite film used for polishing and grinding can be further improved.

[0078] Comparing Example 1 with Examples 8-9, the polishing rate in Examples 8-9 was higher than that in Example 1, and red liquid only appeared after 23 hours in the adhesion stability test between the substrate layer and the TPU film layer. This indicates that by optimizing the amount of epoxy resin, organic sulfonate and hydroxyethyl cellulose, the polishing effect and structural stability of the TPU composite film used for polishing and grinding can be further improved.

[0079] Compared with Examples 11-14, the polishing rate in Examples 11-14 was lower than that in Example 2, and red liquid appeared in the bonding stability test of the substrate layer and TPU film layer in less than 19 hours. This indicates that the polyurethane adhesive prepared by this application can effectively improve the polishing effect and structural stability of the TPU composite film used for polishing and grinding.

[0080] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A TPU composite film for polishing and grinding, characterized in that, It comprises, in sequence, a substrate layer, a polyurethane coating, a TPU film layer, and a protective release layer, wherein the TPU film layer is prepared from the following raw materials in parts by weight: 95-98 parts TPU granules 2-8 parts lubricant The lubricant is composed of polyoxypropylene polyoxyethylene glycerol ether, magnesium stearate and fatty acid amide, wherein the weight ratio of polyoxypropylene polyoxyethylene glycerol ether, magnesium stearate and fatty acid amide is 3:(5-6):1; The TPU film layer also includes 5-10 parts by weight of nano solid filler; The nano solid filler is composed of nano silicon carbide, nano silicon nitride and nano magnesium silicate in a weight ratio of (4-5):2:(3-6); The polyurethane coating is obtained by applying polyurethane adhesive to the surface of a substrate layer. The polyurethane adhesive is prepared from the following raw materials in parts by weight: 20-25 parts of polyether polyol 15-20 parts of polyester polyol 10-15 parts of diphenylmethane diisocyanate 1-2 parts of curing agent Chain extender 0.8-1.2 parts 0.5-1 part catalyst 1-2 parts of surfactant 30-40 parts organic solvent 5-9 parts of modifier The modifier is composed of epoxy resin, organic sulfonate and hydroxyethyl cellulose; The weight ratio of the epoxy resin, the organic sulfonate, and the hydroxyethyl cellulose is 4:(0.5-0.8):

2.

2. The TPU composite film for polishing and grinding according to claim 1, characterized in that, The polyurethane adhesive is prepared by the following method: A: Vacuum dry polyether polyol and polyester polyol at 100-110℃, then cool down to 65-75℃, add diphenylmethane diisocyanate and then add catalyst dropwise, heat up to 90-95℃ and react for 2-4 hours, add chain extender and react for 1-2 hours, cool down to 20-30℃ to obtain polyurethane prepolymer. B: Mix the organic solvent and modifier, then add the curing agent, surfactant and polyurethane prepolymer, stir and mix to obtain polyurethane adhesive.

3. The TPU composite film for polishing and grinding according to claim 1, characterized in that: The thickness of the substrate layer is 0.01-0.2 mm, the thickness of the polyurethane coating is 0.001-0.06 mm, and the thickness of the TPU film layer is 0.01-0.2 mm.

4. The TPU composite film for polishing and grinding according to claim 1, characterized in that: The substrate layer is one of PET substrate layer, PP substrate layer, PC substrate layer or PBT substrate layer.

5. A method for preparing a TPU composite film for polishing and grinding as described in any one of claims 1-4, characterized in that, The preparation steps include the following: S1. Apply polyurethane adhesive to the surface of the substrate layer and cure it to form a polyurethane coating. S2. Mix TPU particles, lubricant and nano solid filler to obtain a mixture, then feed it into a screw extruder to melt it. The molten mixture flows through a die to the surface of the polyurethane coating, cools it, and attach a release protective film to the surface of the TPU film to obtain a TPU composite film for polishing and grinding.

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