Colored polyester thick film and method for manufacturing the same
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NINGBO QINBANG NEW MATERIAL TECH CO LTD
- Filing Date
- 2025-09-23
- Publication Date
- 2026-06-26
Smart Images
Figure SMS_1
Abstract
Description
Technical Field
[0001] This application relates to the field of polyester films, and more specifically to a colored polyester thick film and its preparation method. Background Technology
[0002] Colored polyester film, as an important functional material, is widely used in packaging, decoration, and electronic displays. In the packaging industry, colored polyester film not only enhances the aesthetics of products but also enables product classification and labeling through color differences. In the decoration field, colored polyester film can be used as an interior and exterior decorative material, giving buildings and home environments rich color effects. In the electronic display field, colored polyester film is often used as a filter or protective film, effectively regulating light transmittance and improving display effects. Therefore, colored polyester film plays an indispensable role in multiple industries.
[0003] With the continuous improvement of industrial demands, polyester films with a thickness greater than 100 micrometers are gradually becoming an important market requirement. Thicker polyester films offer higher mechanical strength and durability, enabling them to meet more demanding operating environments. For example, in the construction industry, thicker polyester films can be used as thermal insulation materials or waterproof layers, providing better heat insulation and moisture protection. In the automotive industry, thicker films can be used to manufacture sun visors or interior materials, improving vehicle comfort and safety. Furthermore, thicker polyester films can also serve as insulating layers in electronic components, providing superior electrical performance. Therefore, the development of polyester films with a thickness greater than 100 micrometers has significant practical implications.
[0004] However, existing multilayer composite polyester films have some significant drawbacks in practical applications. First, the complex manufacturing process of multilayer composite films results in high production costs, making it difficult to meet the demands of large-scale production. Second, the insufficient adhesive strength between the multilayer films makes them prone to delamination or peeling during use, affecting product lifespan. Furthermore, the poor thickness uniformity of multilayer composite films can lead to localized performance differences, reducing the overall quality of the product. These problems limit the application of multilayer composite polyester films in high-end fields, necessitating a new technological solution to address these shortcomings. Summary of the Invention
[0005] The purpose of this application is to provide a colored polyester thick film that is both color-stable and structurally stable.
[0006] To achieve the above objectives, the technical solution adopted in this application is as follows: a colored polyester thick film with a thickness greater than 100 µm is provided, comprising a surface layer, an interlayer, and a bottom layer, wherein the raw materials for preparing the bottom layer include: optical polyester chips, pigments, trisodium ethylenediamine disuccinate, and tetrabutyl titanate.
[0007] As a preferred embodiment, the mass ratio of the ethylenediamine disuccinate trisodium salt and the tetrabutyl titanate is (1:2) to (50:1).
[0008] As a preferred embodiment, in the raw materials for preparing the bottom layer, the amount of ethylenediamine disuccinate trisodium added is 0.8% to 12.5% of the mass of the optical polyester chip; and the amount of tetrabutyl titanate added is 0.1% to 2.5% of the mass of the optical polyester chip.
[0009] As a preferred embodiment, the raw materials for preparing the interlayer include: optical polyester chips, pigments, and layered silicates.
[0010] As a preferred embodiment, the layered silicate is any one of montmorillonite, soapstone, or rettosite.
[0011] As a preferred embodiment, in the raw materials for preparing the interlayer, the amount of layered silicate added is 1.6% to 12.5% of the mass of the optical polyester chip.
[0012] As another preferred option, the raw materials for preparing the surface layer include optical polyester chips and polyethylene naphthalate.
[0013] As another preferred embodiment, the thickness of the surface layer is 20-35 µm, the thickness of the interlayer is 30-75 µm, and the thickness of the bottom layer is 50-90 µm.
[0014] As another preferred embodiment, by weight, the raw materials for preparing the surface layer include 50-60 parts of the optical polyester chips and 50-60 parts of the polyethylene naphthalate; the raw materials for preparing the interlayer include 80-120 parts of the optical polyester chips, 1-5 parts of the pigment, and 2-10 parts of the layered silicate; the raw materials for preparing the bottom layer include 80-120 parts of the optical polyester chips, 1-10 parts of the pigment, 1-10 parts of the ethylenediamine disuccinate trisodium salt, and 0.2-2 parts of the tetrabutyl titanate.
[0015] A method for preparing the aforementioned colored polyester thick film is also provided, wherein the raw materials for the preparation of the surface layer, interlayer, and bottom layer are melt-blended in proportion, extruded, and pelletized to obtain surface masterbatch, interlayer masterbatch, and bottom layer masterbatch, respectively; the surface masterbatch, interlayer masterbatch, and bottom layer masterbatch are respectively added to the corresponding hoppers of a co-extruder, melt-plasticized by their respective screws, the melt is combined and compounded through a multi-layer composite die, the flow rate of each layer is distributed according to the designed thickness ratio, and extruded from the die to form a multi-layer film preform; the preform is hot-pressed, cold-cut, and trimmed to obtain the colored polyester thick film.
[0016] Compared with the prior art, the beneficial effects of this application are as follows:
[0017] (1) In this application, pigment and trisodium ethylenediamine disuccinate are added to the base material. The polycarboxyl groups in the molecular structure of trisodium ethylenediamine disuccinate are stable and combined with the metal ions in the pigment, preventing the pigment from changing color or agglomerating due to the migration and oxidation of metal ions during processing or use.
[0018] (2) In this application, tetrabutyl titanate is added to the underlying material to promote the covalent bonding between ethylenediamine disuccinate and optical polyester chips, so that ethylenediamine disuccinate is more firmly anchored in the polyester matrix and avoids losing its stabilizing effect on pigments due to migration and loss.
[0019] (3) In this application, layered silicates are added to the interlayer, and their layered structure can be uniformly dispersed during the melt blending process. The surface properties of the interlayer will form a more precise interaction with the surface of the top and bottom layers, reducing the risk of interlayer peeling and strengthening the overall structural integrity of the entire thick film. Detailed Implementation
[0020] The present application will be further described below with reference to specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.
[0021] The terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.
[0022] This application provides a colored polyester thick film with a thickness greater than 100 µm, which is composed of a multilayer structure, including a surface layer, an interlayer, and a bottom layer. The bottom layer is prepared from optical polyester chips, pigments, trisodium ethylenediamine disuccinate, and tetrabutyl titanate.
[0023] This application improves the compatibility between pigments and optical polyester chips by adding pigments and trisodium ethylenediamine disuccinate to the underlying raw materials, thereby enabling the prepared colored polyester thick film to maintain high transparency, good color development, and stable color.
[0024] While adding trisodium ethylenediamine disuccinate to the substrate material can improve the compatibility between substrate raw materials and the transparency of the resulting substrate, it reduces its mechanical properties and thermal stability. Therefore, tetrabutyl titanate is introduced into the substrate preparation raw materials. The alkoxy groups in the tetrabutyl titanate molecule can react with the terminal hydroxyl groups or ester groups in the PET molecular chain, or generate titanium-oxygen bonds through hydrolysis during processing, forming a partially cross-linked structure, which improves the tensile strength, rigidity and heat resistance of the substrate, reduces thermal degradation during high-temperature processing, and enhances its thermal stability.
[0025] In addition, the addition of tetrabutyl titanate does not affect the transparency of the underlying material, maintaining good visible light transmittance and color rendering, making it more suitable for use in colored polyester films.
[0026] In some embodiments, the amount of tetrabutyl titanate added is closely related to ethylenediamine disuccinate trisodium, and the mass ratio of ethylenediamine disuccinate trisodium to tetrabutyl titanate is (1:2) to (50:1), with a preferred mass ratio of (1:2) to (25:1).
[0027] In the underlying raw materials, the amount of ethylenediamine disuccinate trisodium added is 0.8% to 12.5% of the weight of the optical polyester chips; the amount of tetrabutyl titanate added is 0.1% to 2.5% of the weight of the optical polyester chips.
[0028] The raw materials for preparing the interlayer of the colored polyester thick film in this application include optical polyester chips, pigments, and layered silicates. The interlayer is located between the top layer and the bottom layer, and needs to have good transparency and good adhesion to both the top layer and the bottom layer to prevent peeling between the top layer, the interlayer, and the bottom layer.
[0029] Adding layered silicates to the raw materials for the sandwich structure results in a composite material with good interfacial bonding and essentially maintains the original transparency of the optical polyester chip, making it suitable for applications requiring high-transparency bonding.
[0030] In some embodiments, the amount of layered silicate added is
[0031] The surface materials for the colored polyester thick film of this application include optical polyester chips and polyethylene naphthalate (PEN). The surface material of the colored polyester thick film needs to have good gas barrier properties and chemical stability so that the colored polyester thick film exposed to air for a long time has a longer service life.
[0032] The colored polyester thick film of this application is made of optical polyester chips and polyethylene naphthalate, which has good optical transparency. Polyethylene naphthalate has good water vapor barrier properties and chemical stability, is not easily affected by humid environments, is stable to organic solvents and chemicals, has good acid and alkali resistance, and can appropriately block ultraviolet rays.
[0033] In the preparation of the surface layer, no pigments are added. The color of the colored polyester thick film is mainly presented by the pigments added in the interlayer and the bottom layer. The surface layer has high transparency to let the color show through, which makes the color more natural and uniform.
[0034] In some embodiments, the colored polyester thick film includes a surface layer, an interlayer, and a bottom layer. The surface layer is prepared from optical polyester chips and polyethylene naphthalate. The interlayer is prepared from optical polyester chips, pigments, and layered silicates. The bottom layer is prepared from optical polyester chips, pigments, trisodium ethylenediamine disuccinate, and tetrabutyl titanate.
[0035] In some preferred embodiments, the colored polyester thick film includes a surface layer, an interlayer, and a bottom layer. By weight, the surface layer is prepared from 50-60 parts of optical polyester chips and 50-60 parts of polyethylene naphthalate; the interlayer is prepared from 80-120 parts of optical polyester chips, 1-5 parts of pigment, and 2-10 parts of layered silicate; and the bottom layer is prepared from 80-120 parts of optical polyester chips, 1-10 parts of pigment, 1-10 parts of ethylenediamine disuccinate trisodium salt, and 0.2-2 parts of tetrabutyl titanate.
[0036] Preferably, the pigments for the interlayer and the bottom layer are pigments with metallic components.
[0037] In some embodiments, the thickness of the colored polyester thick film is 100~200 µm.
[0038] In some embodiments, the multilayer structure of the colored polyester thick film has a surface layer thickness smaller than the interlayer or bottom layer thickness, and the interlayer thickness smaller than the bottom layer thickness.
[0039] In some preferred embodiments, the thickness of the surface layer is 20-35 µm, the thickness of the interlayer is 30-75 µm, and the thickness of the bottom layer is 50-90 µm.
[0040] When layered silicates are added to the interlayer, their sheet structure can be uniformly dispersed during melt blending. The surface properties of the interlayer will form a more precise interaction with the surfaces of the top and bottom layers, reducing the risk of interlayer delamination and enhancing the overall structural integrity of the entire thick film.
[0041] In addition, the layered structure of layered silicates can often form a "maze effect" in the sandwich matrix, which delays the penetration of small molecules such as water vapor and oxygen, further enhancing the barrier performance of the entire colored polyester thick film. This synergizes with the function of the surface layer and further improves the material's resistance to environmental erosion.
[0042] Specifically, layered silicates can be any one of montmorillonite, soapstone, or rettosite.
[0043] Adding pigments, ethylenediamine disuccinate (EDDDI) trisodium succinate (EDS) and tetrabutyl titanate to the base material allows the polycarboxyl groups in the EDS molecular structure to stabilize and bind with metal ions in the pigment, preventing discoloration or agglomeration due to metal ion migration or oxidation during processing or use. Tetrabutyl titanate promotes the covalent bonding between EDS and optical polyester chips, anchoring EDS more firmly in the polyester matrix and preventing it from losing its stabilizing effect on the pigment due to migration or loss. Simultaneously, tetrabutyl titanate acts as a coupling agent; one end of its molecule binds to the polyester, while the other end may react with hydroxyl groups on the pigment surface, further strengthening the bond between the pigment and the matrix, reducing pigment agglomeration and sedimentation during processing, and maintaining color uniformity and durability.
[0044] Ethylenediamine disuccinate trisodium is a biodegradable chelating agent, and butanol, a byproduct of the transesterification reaction of tetrabutyl titanate, is easily removed through volatilization, reducing the amount of harmful substances remaining in colored polyester thick films. The combined use of the two avoids the environmental risks that may arise from the leaching of ethylenediamine disuccinate when added alone, while retaining the environmentally friendly properties of ethylenediamine disuccinate trisodium. This allows the underlying material to meet performance requirements while better adapting to the current development needs of "green polymer materials," expanding the application potential of thick films in food packaging, medical fields, and other areas.
[0045] This application also provides a method for preparing a colored polyester thick film: the surface material is melt-blended in proportion, extruded and granulated to obtain a surface masterbatch; the interlayer material is melt-blended, extruded and granulated to obtain an interlayer masterbatch; the bottom layer material is melt-blended, extruded and granulated to obtain a bottom layer masterbatch; the surface masterbatch, interlayer masterbatch and bottom layer masterbatch are respectively added to the corresponding hoppers of a co-extruder, melt-plasticized by their respective screws, the melt is combined through a multi-layer composite die head, the flow rate of each layer is distributed according to the designed thickness ratio, and extruded from the die head to form a multi-layer film preform; the preform is hot-pressed, cold-cut and trimmed to obtain the colored polyester thick film of this application.
[0046] In some embodiments, the raw materials for each layer are first dried: optical polyester chips and polyethylene naphthalate chips are dried in a vacuum oven at 150 °C or above for more than 12 hours to ensure that the moisture content is <0.02% and to prevent hydrolysis during the melting process; and layered silicates, pigments and trisodium ethylenediamine disuccinate are vacuum dried at 100 °C or above for 4 to 6 hours respectively.
[0047] In some embodiments, the extruded die blank is subjected to biaxial hot stretching at 75~80 °C with a stretching ratio of 3~5. This process enhances the overall tensile strength by forming a microfiber structure, while simultaneously controlling the thickness after stretching to remain >100 µm.
[0048] In some preferred embodiments, the stretched multilayer film is placed in a hot press for hot pressing to ensure a tight interlayer structure and uniform and stable thickness.
[0049] Example 1
[0050] A colored polyester thick film is prepared according to the following steps, in parts by weight:
[0051] The raw materials, optical polyester chips and polyethylene naphthalate chips, are dried in a vacuum oven at 150 ℃ or above for more than 12 hours to ensure that the moisture content is <0.02% and to prevent hydrolysis during the melting process; while the soapstone, pigment and trisodium ethylenediamine disuccinate are vacuum dried at 100 ℃ or above for 4 to 6 hours.
[0052] Mix 50 parts of optical polyester chips and 50 parts of polyethylene naphthalate, add to a twin-screw extruder, set nitrogen protection, feed section 200~220 ℃, melt section 240~260 ℃, mixing section 260~290 ℃, die head section 240~260 ℃, screw speed 50~100 rpm, mixing time 3~5 minutes, after extrusion the molten material is rapidly cooled in a water bath, pelletized to obtain surface masterbatch for later use;
[0053] Mix 100 parts of optical polyester chips, 2 parts of pigment and 5 parts of soapstone, add to a twin-screw extruder, and set the parameters of the twin-screw extruder as in the preparation of the surface masterbatch. Pelletize to obtain sandwich masterbatch.
[0054] Mix 100 parts of optical polyester chips, 5 parts of pigment, 5 parts of trisodium ethylenediamine disuccinate and 0.2 parts of tetrabutyl titanate, add to a twin-screw extruder, and set the parameters of the twin-screw extruder as in the preparation of the surface masterbatch. Pelletize to obtain the bottom masterbatch.
[0055] The surface masterbatch, sandwich masterbatch and bottom masterbatch are added to the corresponding hoppers of the three-layer co-extrusion machine, respectively, and melted and plasticized by their respective screws. The temperature is set with reference to the preparation of the surface masterbatch. The melt is combined and merged through a multi-layer composite die head. The die head temperature is set to 240~260 ℃. The flow rate of each layer is distributed according to the design thickness ratio, and the multi-layer die blank is extruded from the die head.
[0056] The extruded preform is subjected to biaxial hot stretching at 75~80 ℃ with a stretch ratio of 3~5 to improve the overall tensile strength by forming a microfiber structure, while controlling the thickness after stretching to remain >100 μm. The stretched multilayer film is placed in a hot press, preheated at 260 ℃ for 5 minutes, vented 10 times, and hot-pressed at 10 MPa pressure for 1 minute to ensure tight bonding between layers and uniform and stable thickness. After hot pressing, it is slowly cooled to room temperature and cut to the specified size as required. The final product thickness must be tested and confirmed to be >100 µm.
[0057] Example 2
[0058] The amount of tetrabutyl titanate added was adjusted to 2 parts, and the other preparation steps were kept the same as those in Example 1.
[0059] Comparative Example 1
[0060] The surface material does not contain polyethylene naphthalate; that is, the surface is prepared using 100 parts of optical polyester chips. Other preparation steps are consistent with the preparation steps in Example 1.
[0061] Comparative Example 2
[0062] No layered silicates were added to the sandwich material, and the other preparation steps were consistent with those in Example 1.
[0063] Comparative Example 3
[0064] The bottom raw materials do not contain ethylenediamine disuccinotrisodium, and the other preparation steps are consistent with the preparation steps in Example 1.
[0065] Comparative Example 4
[0066] Tetrabutyl titanate was not added to the bottom raw materials, and the other preparation steps were consistent with those in Example 1.
[0067] Comparative Example 5
[0068] Tetrabutyl titanate was replaced with silane coupling agent KH560, and the other preparation steps were the same as those in Example 1.
[0069] Performance testing
[0070] 1. Color Stability Test: Color stability is assessed using a five-level rating system. Accelerated aging tests are conducted on an optical-grade transparent colored film within a 3 m × 3 m test area. Digital imaging technology is then used to analyze the percentage of color-changing areas. The rating is based on the percentage of abnormal areas relative to the total test substrate, precisely calculated using professional image processing software. This value directly reflects the material's resistance to photofading. Specific grading standards are as follows:
[0071] Grade A: Color instability in ≤1% of the test area;
[0072] Grade B: Local areas with color instability exceeding 1% and less than or equal to 3%;
[0073] Grade C: Surface area greater than 3% and less than or equal to 5% exhibits unstable color;
[0074] Grade D: Areas with significant color instability exceeding 5% and less than or equal to 7%;
[0075] Grade E: Severe color instability exists in test areas of 7% to 10% or more.
[0076] 2. Tensile strength: Tensile strength testing shall be conducted in accordance with ASTM D-882 standard.
[0077] 3. Interlayer peel strength test: According to GB / T 2790-1995, the specimens of Examples 1-5 and Comparative Examples 1-4 were 200 mm long and (15±1) mm wide. Five specimens were taken in the transverse and five in the longitudinal direction. The width of the specimens was not less than 0.1 mm. The composite material was peeled layer by layer along the length of the specimens. A 180° angle peel test was carried out at a peeling speed of 100 mm / min. The median value of the five test values in the transverse and longitudinal directions was taken as the result.
[0078] 4. Water vapor transmission rate test: After hydrolysis treatment under 85% relative humidity, water vapor transmission rate test shall be conducted in accordance with the test method in BG / T26253-2010.
[0079] The colored polyester thick films prepared in each embodiment and each comparative example were subjected to the above-mentioned performance tests, and the test results are recorded in Table 1 below.
[0080] Table 1 Performance test results of each embodiment and comparative example
[0081]
[0082] Comparative Example 3 showed a color stability grade of only D, far lower than the grade A of Examples 1-2. Disuccinic acid trisodium ethylenediamine, through the combination of polycarboxyl groups in its molecular structure with pigment metal ions, can effectively prevent color changes or agglomeration caused by pigment migration and oxidation, and is the core component for maintaining color stability.
[0083] Comparative Example 4 showed a color stability grade of C, as did Comparative Example 5, while Examples 1 and 2 maintained a grade of A. This indicates that tetrabutyl titanate not only promotes the covalent bonding between ethylenediamine disuccinate trisodium salt and optical polyester chips, but also acts as a coupling agent to strengthen the adhesion between pigments and the matrix. Moreover, its effect is superior to that of the silane coupling agent KH560, further ensuring color uniformity and durability.
[0084] The color stability of both Examples 1 and 2 is Grade A. Within the range of 0.2 to 2 parts, the amount of tetrabutyl titanate added has no significant negative impact on color stability and can be flexibly adjusted to meet other performance requirements.
[0085] The tensile strength of Comparative Example 1 was 52.7 MPa, which was significantly lower than that of Example 1 (65.9 MPa) and Example 2 (63.3 MPa). This demonstrates that adding PEN to the surface layer can improve the overall tensile strength of the thick film by blending it with optical polyester chips, which is directly related to the excellent mechanical properties of PEN itself.
[0086] The tensile strength of Comparative Example 2 was only 36.1 MPa, the lowest among all tested samples. The layered silicates in the interlayer, through uniform dispersion during melt blending, can enhance the overall structural integrity of the thick film. Its effect on improving tensile strength is even better than that of the surface PEN and the bottom tetrabutyl titanate, which is the key support for mechanical properties.
[0087] The surface-to-interlayer peel strength of Comparative Example 2 was 10 N / cm, which was basically the same as that of Examples 1-2, indicating that the bonding strength between the surface layer and the interlayer was less affected by the layered silicate, presumably mainly depending on the compatibility between the surface PEN and the interlayer optical polyester chips. The surface-to-interlayer peel strength of Comparative Example 1 decreased to 5 N / cm. The surface PEN could improve the adhesion between the surface layer and the interlayer by optimizing the interfacial properties, thus preventing interlayer delamination.
[0088] The interlayer-to-substrate peel strength of Comparative Example 4 was only 4 N / cm, far lower than 9 N / cm in Example 1 and 10 N / cm in Example 2; Comparative Example 5 was 6 N / cm, also significantly lower than the examples. This indicates that tetrabutyl titanate, through reaction with the PET molecular chain to form a cross-linked structure, can optimize the interfacial bonding between the substrate and the interlayer, and its effect is better than that of silane coupling agents. The interlayer-to-substrate peel strength of Comparative Example 2 remained at 10 N / cm, indicating that the layered silicate in the interlayer had little impact on the bonding force between the interlayer and the substrate; its role was mainly concentrated on reinforcing the overall structure of the thick film rather than interlayer adhesion.
[0089] Comparative Example 1 showed a water vapor permeability of 1.75 g / cm²·d, which is approximately 62.0% higher than that of Example 1 (1.08 g / cm²·d) and Example 2 (1.12 g / cm²·d). The water vapor barrier properties of the surface PEN significantly reduce the overall water vapor permeability of the thick film. Comparative Example 2 showed a water vapor permeability as high as 1.99 g / cm²·d, the highest among all samples, far exceeding that of Examples 1 and 2. It is speculated that the layered silicate sheet structure creates a "maze effect," thereby delaying the penetration of small molecules. This indicates that it can synergistically interact with the surface PEN, further enhancing the barrier properties of the thick film and reducing the erosion of the thick film by water vapor in the environment.
[0090] The bottom layer component has a relatively small impact on water vapor transmission rate: Although the water vapor transmission rate of Comparative Examples 3-5 is higher than that of Examples 1-2, it is significantly lower than that of Comparative Examples 1-2, indicating that the bottom layer component mainly affects color and mechanical properties, and has a limited contribution to barrier performance.
[0091] In summary, the colored polyester thick film and its preparation method disclosed in this solution are based on a three-layer structure. The surface layer, PEN, enhances barrier properties and stability; the interlayer, layered silicate, strengthens the structure and barrier function; and the bottom layer, using trisodium ethylenediamine disuccinate and tetrabutyl titanate, ensures color stability and mechanical properties. The process is simple and controllable, the raw materials are environmentally friendly, and the product exhibits significant advantages in color stability, mechanical strength, interlayer bonding, and barrier properties, meeting the needs of multiple fields and expanding its application potential in environmentally demanding fields such as food packaging and medical applications.
[0092] The basic principles, main features, and advantages of this application have been described above. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely the principles of this application. Various changes and modifications can be made to this application without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection claimed by this application is defined by the appended claims and their equivalents.
Claims
1. A colored polyester thick film, characterized in that, The material has a thickness greater than 100 µm and includes a surface layer, an interlayer, and a bottom layer. The surface layer is prepared from 50-60 parts of optical polyester chips and 50-60 parts of polyethylene naphthalate. The interlayer is prepared from 80-120 parts of optical polyester chips, 1-5 parts of pigment, and 2-10 parts of layered silicate. The bottom layer is prepared from 80-120 parts of optical polyester chips, 1-10 parts of pigment, 1-10 parts of ethylenediamine disuccinate trisodium salt, and 0.2-2 parts of tetrabutyl titanate. In the preparation materials of the bottom layer, the optical polyester chip is PET, and the mass ratio of ethylenediamine disuccinate trisodium salt and tetrabutyl titanate is (1:2) to (50:1); the amount of ethylenediamine disuccinate trisodium salt added is 0.8% to 12.5% of the mass of the optical polyester chip; the amount of tetrabutyl titanate added is 0.1% to 2.5% of the mass of the optical polyester chip. The amount of layered silicate added is 1.6% to 12.5% of the mass of the optical polyester chips; The pigments in the interlayer and the bottom layer contain metallic components.
2. The colored polyester thick film as described in claim 1, characterized in that, The layered silicate is any one of montmorillonite, soapstone, or rettosite.
3. The colored polyester thick film as described in claim 1, characterized in that, The thickness of the surface layer is 20-35 µm, the thickness of the interlayer is 30-75 µm, and the thickness of the bottom layer is 50-90 µm.
4. The method for preparing the colored polyester thick film according to any one of claims 1 to 3, characterized in that, The raw materials for the preparation of the surface layer, the interlayer, and the bottom layer are melt-blended in proportion, extruded, and pelletized to obtain surface masterbatch, interlayer masterbatch, and bottom layer masterbatch, respectively. The surface masterbatch, interlayer masterbatch, and bottom layer masterbatch are added to the corresponding hoppers of a co-extruder, melted and plasticized by their respective screws, and the melt is combined and compounded through a multi-layer composite die. The flow rate of each layer is distributed according to the designed thickness ratio, and the multi-layer film preform is extruded from the die to form a multi-layer film preform. The film preform is hot-pressed, cold-cut, and trimmed to obtain the colored polyester thick film.