Method for producing modified polyester pellets and method for producing black polyester film
By replacing part of the carbon black powder with modified silica powder, and combining three-layer co-extrusion and biaxial stretching processes, the problems of high cost and carbon black precipitation in fully opaque black polyester film were solved, achieving low cost and high opacity, and improving film toughness.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- YINGKOU KANGHUI PETROCHEM
- Filing Date
- 2025-02-12
- Publication Date
- 2026-06-09
Smart Images
Figure CN119859251B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of polymer materials technology, specifically relating to a method for preparing modified polyester masterbatch and a method for preparing black polyester film, and also relating to the black polyester film prepared therefrom. Background Technology
[0002] BOPET (Bonded Polyester Film) is a film material made from polyethylene terephthalate (PET) through co-extrusion to form cast sheets, followed by biaxial stretching. Due to its excellent barrier properties, temperature resistance, light transmittance, and high strength, it is widely used in various fields such as new packaging, electronics, information technology, optical materials, new energy, and energy-saving window films. However, some products require privacy and necessitate completely light-blocking packaging materials. These materials need to meet the standards of a thickness of 25μm and 0% light transmittance. Currently, domestically produced standard black opaque polyester film products meet this standard, but their price is relatively high.
[0003] Currently, conventional full-light-blocking black polyester film products include a core layer and a surface layer. The core layer uses color masterbatch, and the black masterbatch is usually made of carbon black powder and polyethylene terephthalate (PET). Because carbon black material itself has a small particle size and light weight, the particle size of carbon black powder commonly used in color masterbatch is usually 18-25 nanometers. To meet the current requirements of full-light-blocking black polyester film products, a high concentration (>20%) of carbon black material must be added to the core layer to obtain a product with 0% light transmittance. This results in a high cost for BOPET black polyester film.
[0004] Polyester film itself needs to have an opening agent added to its surface. The purpose of the opening agent is to prevent the polyester films from sticking together after being stacked or rolled up. However, the traditional opening agent is silica, but silica has much worse light-blocking properties than carbon black.
[0005] In addition to the high cost and price of current full-opacity black polyester films, carbon black, due to its small particle size, can precipitate out when added in large quantities during the production and use of black polyester films.
[0006] Based on the above problems, the present invention aims to provide a method for preparing modified polyester masterbatch and a method for preparing black polyester film, so as to obtain a lower cost fully opaque black polyester film while ensuring the light transmittance requirements. Summary of the Invention
[0007] The purpose of this invention is to provide a method for preparing modified polyester masterbatch and a method for preparing black polyester film, and also to provide the prepared black polyester film.
[0008] To achieve the above objectives, the present invention adopts the following technical solution.
[0009] The present invention provides a method for preparing modified polyester masterbatch for black polyester film, comprising the following steps:
[0010] The sucrose solution is dissolved in desalinated water to form a sucrose soaking solution;
[0011] The silica powder is uniformly dispersed into the sucrose soaking solution and soaked for a predetermined time to form a silica sucrose soaking solution;
[0012] The silica-sucrose soaking solution, after soaking for a predetermined time, is placed in an evaporation container and evaporated completely to obtain sucrose-silica.
[0013] Sucrose-silica is placed in a heating furnace and heated to a set temperature and held for a set time to completely carbonize the sucrose and obtain modified silica.
[0014] Modified silica is ground to obtain modified silica powder, which is then uniformly dispersed in an ethylene glycol solution. The ethylene glycol solution containing the modified silica powder is then mixed with terephthalic acid and subjected to a polymerization reaction to obtain a modified PET polyester masterbatch for preparing the surface layer of a black polyester film.
[0015] When dissolving sucrose solution in desalinated water, the mass of the sucrose solution is 20%-80% of the mass of the desalinated water.
[0016] In this process, silica powder is uniformly dispersed in the sucrose soaking solution and soaked for 24 hours.
[0017] In this process, sucrose-silica is placed in a muffle furnace and heated to 600°C and held for 6 hours to completely carbonize the sucrose and obtain modified silica.
[0018] The silica powder is prepared by a gas-phase method and has a particle size of 3.5 μm.
[0019] Another invention provides a method for preparing a low-cost black polyester film, comprising the following steps:
[0020] S1. The modified PET polyester masterbatch prepared by the above preparation method is mixed and blended with the first PET polyester chips to form a surface material. The content of modified silica powder in the surface material mixture is 10,000 ppm.
[0021] S2. Mix the second PET polyester chips and color masterbatch at a mass ratio of (85-95):(5-15) to form the core layer raw material.
[0022] S3. The core layer material enters the main extruder and melts into a core layer melt under a set melting temperature. The surface layer material enters the auxiliary extruder and melts into a surface layer melt under a set melting temperature. The core layer melt and the surface layer melt are extruded from the main extruder and the auxiliary extruder, respectively, and then conveyed to the adapter module. After passing through the internal flow channel of the adapter module, they are separated into layers. The core layer melt is distributed in the core layer after being separated into layers, and the surface layer melt is distributed in the upper and lower surface layers after being separated into layers.
[0023] S4. The allocated core melt and surface melt are fed into a three-layer co-extrusion die. The core melt is extruded from the middle layer of the three-layer co-extrusion die. At the same time, the surface melt of the upper and lower layers is extruded from the upper and lower layers of the three-layer co-extrusion die, respectively. The melt extruded from the three-layer co-extrusion die is cooled at a set cooling temperature and then cast into a polyester film sheet.
[0024] S5. The polyester film sheet is preheated, stretched, and then reheated and shaped before being cooled to room temperature to form a black polyester film.
[0025] The melting temperature of the main extruder and the auxiliary extruder is 278°C, and the raw materials of the color masterbatch include carbon black powder and polyethylene terephthalate.
[0026] The core melt and the surface melt are extruded from the main extruder and the auxiliary extruder, respectively, and then transported to the adapter module after passing through their respective pre-filters, metering pumps, and fine filters. The melt extruded from the three-layer co-extrusion die is cooled at 15°C and then cast into a polyester film sheet.
[0027] The polyester film sheet is preheated to 90°C and then longitudinally stretched at 90°C with a longitudinal stretching ratio of 3.3. After being preheated to 105°C, it is then transversely stretched with a transverse stretching ratio of 3.7. After being heat-set at 200°C, it is cooled to room temperature and finally wound up to obtain a fully opaque black polyester film.
[0028] Another aspect of the present invention provides a low-cost black polyester film, which is prepared by the above-described method for preparing low-cost black polyester film.
[0029] In the technical solution provided by this invention, silica powder is uniformly dispersed in a sucrose soaking solution and soaked for a predetermined time. Then, it is evaporated to obtain sucrose-silica. This sucrose is then heated and kept at a specific temperature in a furnace to completely carbonize the sucrose, obtaining modified silica. Subsequently, an ethylene glycol solution containing the modified silica powder is mixed with terephthalic acid and polymerized to obtain modified PET polyester masterbatch, which is used to prepare the surface layer of a black polyester film, effectively blocking light. Thus, silica is modified through processes such as sucrose solution soaking, calcination, and ball milling to obtain black modified silica, thereby replacing part of the carbon black material used in film surface preparation. In the production of fully opaque black polyester films, the amount of carbon black powder added to the core layer can be greatly reduced, thereby reducing production costs. Furthermore, carbon black, due to its small particle size, can precipitate during the production and use of black polyester films. This invention uses modified silica to replace a large amount of carbon black powder, which can improve the carbon black precipitation problem to some extent. In other words, this invention reduces film production costs and improves the carbon black precipitation problem.
[0030] The present invention uses silica prepared by the gas phase method, which has a porous surface structure and can more easily absorb a large amount of sucrose solution.
[0031] Increasing the amount of carbon black added to the core layer or using carbon black material with a larger particle size will increase the crystallinity of the polyester film, making the film brittle and easy to break. This application can also improve the toughness of the black polyester film by reducing the amount of carbon black added, thus preventing the film from becoming brittle and easy to break. Attached Figure Description
[0032] Figure 1 This is a schematic diagram of the structure of the low-cost black polyester film of the present invention.
[0033] Figure 2 This is a schematic diagram of the structure of existing polyester films.
[0034] In the diagram: 1. Silica powder; 2. Carbon black powder; 3. Modified silica powder; 4. Surface layer; 5. Core layer. Detailed Implementation
[0035] The technical solution of the present invention will be further described in detail below. Those skilled in the art should understand that the specific embodiments described are merely illustrative of the invention and should not be considered as specific limitations thereof.
[0036] It should be noted that, unless otherwise specified, the technical means used in the following examples are conventional means well known to those skilled in the art. Unless otherwise specified, the raw materials used in this invention are all commercially available conventional commodities, all of which can be obtained through purchase.
[0037] The present invention provides a method for preparing modified polyester masterbatch for black polyester film, comprising the following steps:
[0038] The sucrose solution is dissolved in desalinated water to form a sucrose soaking solution;
[0039] The silica powder is uniformly dispersed into the sucrose soaking solution and soaked for a predetermined time to form a silica sucrose soaking solution;
[0040] The silica-sucrose soaking solution, after soaking for a predetermined time, is placed in an evaporation container and evaporated completely to obtain sucrose-silica.
[0041] Sucrose-silica is placed in a heating furnace and heated to a set temperature and held for a set time to completely carbonize the sucrose and obtain modified silica.
[0042] Modified silica is ground to obtain modified silica powder, which is then uniformly dispersed in an ethylene glycol solution. The ethylene glycol solution containing the modified silica powder is then mixed with terephthalic acid and subjected to a polymerization reaction to obtain a modified PET polyester masterbatch for preparing the surface layer of a black polyester film.
[0043] This invention discloses a method for preparing a fully opaque black polyester film. By employing a process of sucrose soaking, muffle furnace calcination, ball milling dispersion, and blending polymerization of a surface silica opening agent, a novel surface opening agent is obtained to meet the optical properties of the polyester film, thereby reducing material costs. This invention starts with raw material modification to improve the opacity of the surface material, thus reducing the amount of new layer material required and achieving cost reduction. This invention belongs to the field of polyester film technology, where a novel surface opening agent is obtained from the surface raw materials through processes such as modification, calcination, ball milling dispersion, and polymerization, thereby improving the material's opacity.
[0044] In this invention, the process of dissolving the sucrose solution in desalinated water specifically involves the following: the mass of the sucrose solution is 20%-80% of the mass of the desalinated water.
[0045] In this invention, silica powder is uniformly dispersed in the sucrose soaking solution and soaked for 24 hours.
[0046] In this invention, sucrose-silica is placed in a muffle furnace and heated to 600°C and held for 6 hours to completely carbonize the sucrose and obtain modified silica.
[0047] In this invention, the silica powder is prepared by a gas-phase method and has a particle size of 3.5 μm. In this invention, the particle size of the modified silica powder is the same as that of the raw silica powder.
[0048] The present invention provides a method for preparing a low-cost black polyester film, comprising the following steps:
[0049] S1. The modified PET polyester masterbatch prepared by the above preparation method is mixed and blended with the first PET polyester chips to form a surface material. The content of modified silica powder in the surface material mixture is 10,000 ppm.
[0050] S2. Mix the second PET polyester chips and color masterbatch at a mass ratio of (85-95):(5-15) to form the core layer raw material.
[0051] S3. The core layer material enters the main extruder and melts into a core layer melt under a set melting temperature. The surface layer material enters the auxiliary extruder and melts into a surface layer melt under a set melting temperature. The core layer melt and the surface layer melt are extruded from the main extruder and the auxiliary extruder, respectively, and then conveyed to the adapter module. After passing through the internal flow channel of the adapter module, they are separated into layers. The core layer melt is distributed in the core layer after being separated into layers, and the surface layer melt is distributed in the upper and lower surface layers after being separated into layers.
[0052] S4. The allocated core melt and surface melt are fed into a three-layer co-extrusion die. The core melt is extruded from the middle layer of the three-layer co-extrusion die. At the same time, the surface melt of the upper and lower layers is extruded from the upper and lower layers of the three-layer co-extrusion die, respectively. The melt extruded from the three-layer co-extrusion die is cooled at a set cooling temperature and then cast into a polyester film sheet.
[0053] S5. The polyester film sheet is preheated, stretched, and then reheated and shaped before being cooled to room temperature to form a black polyester film.
[0054] like Figure 1 and Figure 2 As shown, the surface layer 4 of the black polyester film prepared in this embodiment contains the modified PET polyester masterbatch prepared in this application. The modified PET polyester masterbatch contains modified silica powder 3. Figure 1 As shown, the amount of carbon black powder 2 in the core layer 5 of the black polyester film of this application is significantly less than that in the other two applications. Figure 2 The amount of carbon black powder in the core layer 5 of existing polyester films. Figure 2 The silica powder 1 in the surface layer of the polyester film is white.
[0055] The silica used in the opening agent masterbatch added to the surface of polyester film typically has a particle size of about 3.5 μm, which is larger. After silica modification, adding a small amount of silica can replace more carbon black, thereby reducing costs in one step.
[0056] In this invention, the melting temperature of the main extruder and the auxiliary extruder is 278°C, and the color masterbatch is mainly composed of carbon black powder and polyethylene terephthalate.
[0057] In this invention, the core melt and the surface melt are extruded from the main extruder and the auxiliary extruder, respectively, and then transported to the adapter module after passing through their respective pre-filters, metering pumps, and fine filters. The melt extruded from the three-layer co-extrusion die is cooled at 15°C and then cast into a polyester film sheet.
[0058] In this invention, the polyester film sheet is preheated to 90°C and longitudinally stretched at 90°C with a longitudinal stretching ratio of 3.3. Then, after preheating at 105°C, it is transversely stretched with a transverse stretching ratio of 3.7. After heat setting at 200°C, it is cooled to room temperature and finally traction-wound to obtain a fully opaque black polyester film.
[0059] The low-cost black polyester film provided by this invention is prepared by the above-described method for preparing low-cost black polyester film.
[0060] The following detailed description uses specific comparative examples and embodiments.
[0061] Comparative Example 1
[0062] Step 1: Disperse silica evenly in ethylene glycol solution, mix ethylene glycol and terephthalic acid and obtain PET polyester masterbatch through polymerization reaction.
[0063] Step 2: Mix the PET polyester masterbatch from Step 1 with PET polyester chips at a silica powder content of 10,000 ppm.
[0064] Step 3: Mix the PET polyester chips and color masterbatch at a mass ratio of 80:20.
[0065] Step 4: The raw materials prepared in Step 2 are fed into the auxiliary extruder by suction, and the raw materials prepared in Step 3 are fed into the main extruder by suction. They are then melt-extruded at 278°C. The melt passes through the pre-filter, metering pump, and fine filter of the main extruder and the auxiliary extruder, respectively, and is then uniformly transported to the adapter module. After passing through the internal flow channel of the adapter, the melt from the main extruder is distributed in the core layer, and the melt from the auxiliary extruder is distributed in the upper and lower surface layers.
[0066] Step 5: The distributed melt enters the three-layer co-extrusion die. The core layer melt is extruded from the middle layer of the three-layer co-extrusion die. At the same time, the upper and lower surface layer melts are extruded from the upper and lower layers of the three-layer co-extrusion die, respectively. After the extruded melt is cooled at 15°C, it is cast into a sheet to obtain a polyester film.
[0067] Step 6: Preheat the polyester film sheet obtained in Step 5 to 90°C and stretch it longitudinally at this temperature with a longitudinal stretching ratio of 3.3. Then, after preheating at 105°C, stretch it transversely with a transverse stretching ratio of 3.7. After heat setting at 200°C, cool it to room temperature and finally roll it up by traction to obtain a fully opaque black polyester film.
[0068] The obtained conventional polyester film has a three-layer composite structure, with two outer layers consisting of conventional masterbatch plus PET polyester, and a core layer consisting of color masterbatch plus PET polyester. The thickness of the conventional fully opaque black polyester film is 25 μm, with the core layer thickness at 22.5 μm and the top and bottom outer layers at 1.25 μm. The properties of the conventional fully opaque black polyester film are as follows:
[0069] performance index Light transmittance 0％ L 39.81 a 0.16 b -0.96
[0070] The meanings of L, a, and b are as follows: L value: Represents the brightness of an object, that is, the lightness and darkness of a color. The L value ranges from 0 to 100. The higher the value, the lighter the color, closer to white; the lower the value, the darker the color, closer to black. a value: Represents red-green tint. The a value ranges from -128 to +128. Positive values indicate a reddish tint, and negative values indicate a greenish tint. b value: Represents yellow-blue tint. The b value also ranges from -128 to +128. Positive values indicate a yellowish tint, and negative values indicate a bluish tint.
[0071] Example 1
[0072] This embodiment provides a low-cost, fully opaque black polyester film preparation method, including the following steps:
[0073] Step 1: Take a container and dissolve the sucrose solution in the desalinated water at a mass ratio of 20%.
[0074] Step 2: Disperse the silica powder evenly into the solution prepared in Step 1 and soak for 24 hours.
[0075] Step 3: Place the solution from Step 2 in an evaporating dish and evaporate the solution completely to obtain sucrose-silica.
[0076] Step 4: Place the sucrose-silica obtained in Step 3 in a muffle furnace and keep it at 600℃ for 6 hours to allow the sucrose to completely carbonize and obtain modified silica.
[0077] Step 5: Ball mill and disperse the modified silica from Step 4 until the dispersion degree is the same as that of the silica powder in Step 2, to obtain modified silica powder.
[0078] Step 6: Disperse the modified silica powder from Step 5 evenly into an ethylene glycol solution, mix the ethylene glycol and terephthalic acid, and obtain the modified PET polyester masterbatch through a polymerization reaction.
[0079] Step 7: Mix the modified PET polyester masterbatch from Step 6 with PET polyester chips at a content of 10,000 ppm of modified silica powder.
[0080] Step 8: Mix the PET polyester chips and color masterbatch at a ratio of 85:15.
[0081] Step 9: The raw materials prepared in Step 7 are fed into the auxiliary extruder by suction, and the raw materials prepared in Step 8 are fed into the main extruder by suction. The materials are then melt-extruded at 278°C. The melt is then transported to the adapter module after passing through the pre-filter, metering pump, and fine filter of the main extruder and the auxiliary extruder, respectively. After passing through the internal flow channel of the adapter, the melt is stratified. The melt from the main extruder is distributed in the core layer, and the melt from the auxiliary extruder is distributed in the upper and lower surface layers.
[0082] Step 10: The distributed melt enters the three-layer co-extrusion die. The core layer melt is extruded from the middle layer of the three-layer co-extrusion die. At the same time, the upper and lower surface layer melts are extruded from the upper and lower layers of the three-layer co-extrusion die, respectively. After the extruded melt is cooled at 15°C, it is cast into a sheet to obtain a polyester film.
[0083] Step 11: Preheat the polyester film sheet obtained in Step 10 to 90°C and stretch it longitudinally at this temperature with a longitudinal stretching ratio of 3.3. Then, after preheating at 105°C, stretch it transversely with a transverse stretching ratio of 3.7. After heat setting at 200°C, cool it to room temperature and finally roll it up by traction to obtain a fully opaque black polyester film.
[0084] The obtained conventional polyester film has a three-layer composite structure, with two outer layers consisting of modified PEI polyester masterbatch and PET polyester, and a core layer consisting of color masterbatch and PET polyester. The thickness of the conventional fully opaque black polyester film is 25 μm, with the core layer being 22.5 μm thick and the top and bottom outer layers being 1.25 μm thick. The properties of the modified masterbatch fully opaque black polyester film are as follows:
[0085] performance index Light transmittance 0％ L 38.99 a 0.14 b -0.92
[0086] Example 2
[0087] This embodiment provides a low-cost method for preparing a fully opaque black polyester film.
[0088] Step 1: Take a container and dissolve the sucrose solution in the desalinated water at a mass ratio of 50%.
[0089] Step 2: Disperse the silica powder evenly into the solution prepared in Step 1 and soak for 24 hours.
[0090] Step 3: Place the solution from Step 2 in an evaporating dish and evaporate the solution completely to obtain sucrose-silica.
[0091] Step 4: Place the sucrose-silica obtained in Step 3 in a muffle furnace and keep it at 600℃ for 6 hours to allow the sucrose to completely carbonize and obtain modified silica.
[0092] Step 5: Ball mill and disperse the modified silica from Step 4 until the dispersion degree is the same as that of the silica powder in Step 2, to obtain modified silica powder.
[0093] Step 6: Disperse the modified silica powder from Step 5 evenly into an ethylene glycol solution, mix the ethylene glycol and terephthalic acid, and obtain the modified PET polyester masterbatch through a polymerization reaction.
[0094] Step 7: Mix the modified PET polyester masterbatch from Step 6 with PET polyester chips at a content of 10,000 ppm of modified silica powder.
[0095] Step 8: Mix the PET polyester chips and color masterbatch at a ratio of 90:10.
[0096] Step 9: The raw materials prepared in Step 7 are fed into the auxiliary extruder by suction, and the raw materials prepared in Step 8 are fed into the main extruder by suction. The materials are then melt-extruded at 278°C. The melt is then transported to the adapter module after passing through the pre-filter, metering pump, and fine filter of the main extruder and the auxiliary extruder, respectively. After passing through the internal flow channel of the adapter, the melt is stratified. The melt from the main extruder is distributed in the core layer, and the melt from the auxiliary extruder is distributed in the upper and lower surface layers.
[0097] Step 10: The distributed melt enters the three-layer co-extrusion die. The core layer melt is extruded from the middle layer of the three-layer co-extrusion die. At the same time, the upper and lower surface layer melts are extruded from the upper and lower layers of the three-layer co-extrusion die, respectively. After the extruded melt is cooled at 15°C, it is cast into a sheet to obtain a polyester film.
[0098] Step 11: Preheat the polyester film sheet obtained in Step 10 to 90°C and stretch it longitudinally at this temperature with a longitudinal stretching ratio of 3.3. Then, after preheating at 105°C, stretch it transversely with a transverse stretching ratio of 3.7. After heat setting at 200°C, cool it to room temperature and finally roll it up by traction to obtain a fully opaque black polyester film.
[0099] The obtained conventional polyester film has a three-layer composite structure, with two outer layers consisting of modified PEI polyester masterbatch and PET polyester, and a core layer consisting of color masterbatch and PET polyester. The thickness of the conventional fully opaque black polyester film is 25 μm, with the core layer being 22.5 μm thick and the top and bottom outer layers being 1.25 μm thick. The properties of the modified masterbatch fully opaque black polyester film are as follows:
[0100] performance index Light transmittance 0％ L 39.32 a 0.17 b -0.99
[0101] Example 3
[0102] This embodiment provides a low-cost method for preparing a fully opaque black polyester film.
[0103] Step 1: Take a container and dissolve the sucrose solution in the desalinated water at a mass ratio of 80%.
[0104] Step 2: Disperse the silica powder evenly into the solution prepared in Step 1 and soak for 24 hours.
[0105] Step 3: Place the solution from Step 2 in an evaporating dish and evaporate the solution completely to obtain sucrose-silica.
[0106] Step 4: Place the sucrose-silica obtained in Step 3 in a muffle furnace and keep it at 600℃ for 6 hours to allow the sucrose to completely carbonize and obtain modified silica.
[0107] Step 5: Ball mill and disperse the modified silica from Step 4 until the dispersion degree is the same as that of the silica powder in Step 2, to obtain modified silica powder.
[0108] Step 6: Disperse the modified silica powder from Step 5 evenly into an ethylene glycol solution, mix the ethylene glycol and terephthalic acid, and obtain the modified PET polyester masterbatch through a polymerization reaction.
[0109] Step 7: Mix the modified PET polyester masterbatch from Step 6 with PET polyester chips at a content of 10,000 ppm of modified silica powder.
[0110] Step 8: Mix the PET polyester chips and color masterbatch at a ratio of 95:5.
[0111] Step 9: The raw materials prepared in Step 7 are fed into the auxiliary extruder by suction, and the raw materials prepared in Step 8 are fed into the main extruder by suction. The materials are then melt-extruded at 278°C. The melt is then transported to the adapter module after passing through the pre-filter, metering pump, and fine filter of the main extruder and the auxiliary extruder, respectively. After passing through the internal flow channel of the adapter, the melt is stratified. The melt from the main extruder is distributed in the core layer, and the melt from the auxiliary extruder is distributed in the upper and lower surface layers.
[0112] Step 10: The distributed melt enters the three-layer co-extrusion die. The core layer melt is extruded from the middle layer of the three-layer co-extrusion die. At the same time, the upper and lower surface layer melts are extruded from the upper and lower layers of the three-layer co-extrusion die, respectively. After the extruded melt is cooled at 15°C, it is cast into a sheet to obtain a polyester film.
[0113] Step 11: Preheat the polyester film sheet obtained in Step 10 to 90°C and stretch it longitudinally at this temperature with a longitudinal stretching ratio of 3.3. Then, after preheating at 105°C, stretch it transversely with a transverse stretching ratio of 3.7. After heat setting at 200°C, cool it to room temperature and finally roll it up by traction to obtain a fully opaque black polyester film.
[0114] The obtained conventional polyester film has a three-layer composite structure, with two outer layers consisting of modified PEI polyester masterbatch and PET polyester, and a core layer consisting of color masterbatch and PET polyester. The thickness of the conventional fully opaque black polyester film is 25 μm, with the core layer being 22.5 μm thick and the top and bottom outer layers being 1.25 μm thick. The properties of the modified masterbatch fully opaque black polyester film are as follows:
[0115]
[0116]
[0117] As can be seen from the list of polyester film performance indicators obtained by the comparative examples and embodiments of this application, the performance of the modified masterbatch fully opaque black polyester film obtained by the three embodiments of this application is not significantly different from the performance of the conventional fully opaque black polyester film obtained by the comparative examples.
[0118] However, by modifying silica with sucrose solution to obtain modified silica powder, and then obtaining modified polyester masterbatch, which is used as a surface material to prepare the upper and lower surface layers of black polyester film, the use of core layer raw material color masterbatch (core layer carbon black powder) can be reduced while ensuring full light-blocking performance. This greatly reduces the amount of core layer carbon black powder added, thereby reducing production costs.
[0119] Furthermore, through a comparison of the three embodiments of this application, it can be seen that the mass percentage of sucrose solution gradually increases from 20% to 80% by mass when dissolved in desalinated water. Meanwhile, the mass ratio of PET polyester chips to masterbatch in the core layer raw material can be adjusted from 85:15 to 95:5, and the amount of masterbatch added gradually decreases. Thus, it can be seen that the greater the amount of sucrose solution added, the less the amount of masterbatch (core layer carbon black powder) can be added, further reducing production costs. As a large-scale production and R&D enterprise, the applicant's cost reduction benefits are very significant.
[0120] The fully opaque polyester film obtained by this patent can reduce costs by 10%, and at the same time, reducing the amount of carbon black added to the core layer can greatly optimize the problem of carbon black precipitation.
[0121] The proposed solution has the following advantages:
[0122] 1. By modifying silicon dioxide with sucrose solution, the silicon dioxide is transformed from white powder to black powder through a carbonization process, which makes up for the disadvantage that silicon dioxide is not as good as carbon black in terms of light blocking effect.
[0123] 2. Applying sucrose-modified silica powder to the field of biaxially oriented polyester film is a novel process that has not yet been discovered. This process is simple to operate and has obvious cost advantages.
[0124] 3. The production cost of the modified masterbatch fully opaque black polyester film obtained by this invention is about 10% lower than that of conventional fully opaque black polyester film, which is a very obvious advantage.
[0125] This application employs a modification-calcination method to obtain modified silica powder. This powder can significantly reduce the amount of carbon black powder added to the core layer during the production of fully opaque black polyester film, thereby reducing production costs. Furthermore, due to its small particle size, carbon black can precipitate during the production and use of black polyester film. This invention uses modified silica to replace a large amount of carbon black powder, which can improve the carbon black precipitation problem to some extent. This invention reduces film production costs and improves carbon black precipitation, creating higher product value.
[0126] This application can also improve the toughness of black polyester film and prevent the film from becoming brittle and easily broken. Increasing the amount of carbon black added to the core layer, or using carbon black material with a larger particle size, will have a significant impact on the success rate of film production. Because carbon black material has good heat absorption and thermal conductivity, increasing the amount added will increase the crystallinity of the polyester film, leading to the film becoming brittle and easily broken.
[0127] 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 changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.
Claims
1. A method for preparing a black polyester film, characterized in that, Including the following steps: S1. The modified PET polyester masterbatch is mixed with the first PET polyester chips to form a surface material. The content of modified silica powder in the surface material mixture is 10,000 ppm. S2. The second PET polyester chips and color masterbatch are mixed at a mass ratio of (85-95):(5-15) to form the core layer raw material; the raw material of the color masterbatch includes carbon black powder and polyethylene terephthalate. S3. The core layer material enters the main extruder and melts into a core layer melt at 278°C. The surface layer material enters the auxiliary extruder and melts into a surface layer melt at 278°C. The core layer melt and the surface layer melt are extruded from the main extruder and the auxiliary extruder, respectively, and then conveyed to the adapter module. After passing through the internal flow channel of the adapter module, they are separated into layers. The core layer melt is distributed in the core layer after being separated into layers, and the surface layer melt is distributed in the upper and lower surface layers after being separated into layers. S4. The allocated core melt and surface melt are fed into a three-layer co-extrusion die. The core melt is extruded from the middle layer of the three-layer co-extrusion die. At the same time, the surface melt of the upper and lower layers is extruded from the upper and lower layers of the three-layer co-extrusion die, respectively. The melt extruded from the three-layer co-extrusion die is cooled at a set cooling temperature and then cast into a polyester film sheet. S5. The polyester film sheet is preheated, stretched, and then reheated and shaped before being cooled to room temperature to form a black polyester film. The preparation method of the modified PET polyester masterbatch in S1 includes: The sucrose solution is dissolved in desalinated water to form a sucrose soaking solution; The silica powder is uniformly dispersed in the sucrose soaking solution and soaked for 24 hours to form a silica sucrose soaking solution. The silica-sucrose soaking solution, after soaking for a predetermined time, is placed in an evaporation container and evaporated completely to obtain sucrose-silica. Sucrose-silica was placed in a muffle furnace and heated to 600°C and held for 6 hours to completely carbonize the sucrose and obtain modified silica. Modified silica is ground to obtain modified silica powder, which is then uniformly dispersed in an ethylene glycol solution. The ethylene glycol solution containing the modified silica powder is then mixed with terephthalic acid and subjected to a polymerization reaction to obtain a modified PET polyester masterbatch for preparing the surface layer of a black polyester film.
2. The method for preparing the black polyester film according to claim 1, characterized in that, When dissolving sucrose solution in desalinated water, the mass of the sucrose solution should be 20%-80% of the mass of the desalinated water.
3. The method for preparing the black polyester film according to claim 1, characterized in that, The silica powder was prepared by a gas-phase method and has a particle size of 3.5 μm.
4. The method for preparing the black polyester film according to claim 1, characterized in that: The core melt and surface melt are extruded from the main extruder and auxiliary extruder, respectively, and then transported to the adapter module after passing through their respective pre-filters, metering pumps, and fine filters. The melt extruded from the three-layer co-extrusion die is cooled at 15°C and then cast into a polyester film sheet.
5. The method for preparing the black polyester film according to claim 4, characterized in that: The polyester film sheet is preheated to 90°C and then longitudinally stretched at 90°C with a longitudinal stretching ratio of 3.
3. After being preheated to 105°C, it is then transversely stretched with a transverse stretching ratio of 3.
7. After being heat-set at 200°C, it is cooled to room temperature and finally wound up to obtain a fully opaque black polyester film.
6. A black polyester film, characterized in that: The black polyester film is prepared by the method described in any one of claims 1-5.