CPP colorful film and preparation method thereof

Abstract

The invention discloses a CPP color intrigue film and a preparation method thereof, and relates to the field of CPP color intrigue film.The preparation method comprises the steps that nano silicon dioxide is subjected to ultrasonic dispersion, then a silane coupling agent is added for reflux activation, then graft polymerization with glycidyl laurate and an initiator solution is conducted, purification and drying are conducted, and a reactive core-shell nano toughening agent is obtained; the preparation method comprises the following steps: carrying out ring opening on maleic anhydride grafted polypropylene and diamine to obtain an intermediate, adding epoxy-terminated polydimethylsiloxane, carrying out gradient heating grafting, recovering a solvent, granulating to obtain a molecular anchored self-stripping copolymer, premixing the two raw materials with polyethylene wax and an auxiliary material at a high speed, and carrying out twin-screw extrusion granulation to obtain an enhanced functional material. And finally, carrying out asymmetric co-extrusion on the composite film serving as a functional layer and casting-grade polypropylene serving as a substrate layer to form the composite film, and carrying out infrared preheating, micro-nano imprinting and chilling shaping to obtain the CPP color intrigue film, so that the problems of dynamic contradiction of interface adhesive force and mismatch of thermal stress are solved.

Description

Technical Field

[0001] The present invention relates to the field of CPP magic color film preparation, and in particular to a CPP magic color film and a preparation method thereof. Background Art

[0002] In the field of CPP iridescent film manufacturing, existing technologies face core technical bottlenecks: First, the dynamic contradiction between interfacial adhesion and thermal stress mismatch leads to insufficient cohesive strength of the functional layer, resulting in incomplete microstructure replication under high pressure. For example, the traditional process has a fidelity of less than 80% after 500 hours. Functional components such as siloxane migrate into the mold and cause contamination, causing optical degradation of the product. In the non-anchored PDMS process, the mold silicon content exceeds the standard after 500 hours, resulting in a fidelity of only 75%. Second, the traditional process relies on PET release film or simple blending systems, which suffer from high peel forces of approximately 200mN / inch, thermal stress damage to the film, and PDMS migration and contamination of the mold. This results in a short continuous production cycle of only 50 hours, high mold maintenance costs, a low yield of approximately 70%, and insufficient optical structure fidelity of less than 99%. Summary of the Invention

[0003] In order to solve the above technical problems, the present invention provides a CPP fantasy color film and a preparation method thereof, which solves the problems of dynamic contradiction of interface adhesion and thermal stress mismatch.

[0004] In order to achieve the above object, the present invention provides a method for preparing a CPP fantasy color film, comprising the following steps: Step 1: Prepare two core raw materials: Preparation of a reactive core-shell nano-toughening agent: Ultrasonic dispersion of nano-silica in a solvent, addition of a silane coupling agent, and reflux reaction to obtain surface-activated nano-silica; mixing the activated nano-silica with a solution containing glycidyl laurate and an initiator, performing a graft polymerization reaction, and purifying and drying to obtain the reactive core-shell nano-toughening agent; Preparation of a molecular anchored self-exfoliating copolymer: Maleic anhydride grafted polypropylene and a diamine are subjected to a ring-opening reaction in a solvent to prepare an amino-modified polypropylene intermediate; epoxy-terminated polydimethylsiloxane is added to the intermediate, and a grafting reaction is carried out using a gradient temperature ramp. After solvent recovery and granulation, the molecular anchored self-exfoliating copolymer is obtained; Step 2: preparing an enhanced functional material: pre-mixing the reactive core-shell nano toughening agent, the molecular anchoring self-exfoliating copolymer, the polyethylene wax and the auxiliary materials prepared in step 1 at high speed, then melt-blending them through a twin-screw extruder, and extruding and granulating them to obtain an enhanced functional material; Step three, forming and preparing CPP fantasy color film: adopting an asymmetric co-extrusion process, the enhanced functional material is used as the functional layer, and the cast-grade polypropylene resin is used as the base layer, and a composite film is formed by co-extrusion through a T-die; the composite film is subjected to infrared preheating, micro-nano imprinting and chilling shaping in sequence, and the micro-nano structure is replicated on the surface of the functional layer, and the composite film and the imprinting mold are non-destructively peeled off, and finally the CPP fantasy color film is obtained.

[0005] Preferably, the particle size of the nano-silica is 15 nm; the silane coupling agent is γ-aminopropyltriethoxysilane; the amount thereof is 3-8% of the mass of the nano-silica; and the temperature of the reflux reaction is 110°C.

[0006] Preferably, the temperature of the ring-opening reaction is 130°C; and the insulation reaction temperature of the grafting reaction is 120°C.

[0007] Preferably, the weight ratio of the enhanced functional material, the molecular anchoring self-exfoliating copolymer, the reactive core-shell nano toughening agent, and the polyethylene wax additive is 80:(8-12):(8-12).

[0008] Preferably, the interface temperature of the functional layer of the micro-nano imprinting is controlled at 145°C ± 3°C, and the imprinting pressure is 15 MPa; and the temperature of the chilling and shaping is controlled at -10°C ± 2°C.

[0009] A CPP iridescent film, comprising: a base layer made of cast-grade polypropylene resin; a functional layer composited on the base layer and having a micro-nano structure, the functional layer comprising the following components: (a) Molecular anchored self-exfoliating copolymer: the reaction product of maleic anhydride grafted polypropylene, 1,6-hexanediamine, and epoxy-terminated polydimethylsiloxane; (b) Reactive core-shell nanotougheners: They have a core-shell structure with nano-silica as the core and an epoxy-containing polymer as the shell; (c) Polyethylene wax additive.

[0010] Preferably, the thickness ratio of the base layer to the functional layer is (4-5):1.

[0011] Preferably, the thickness of the functional layer is 0.5-1.0 μm.

[0012] Preferably, the grafting density of the polydimethylsiloxane segments in the molecular anchored self-exfoliating copolymer is 1.2 mmol / g.

[0013] Compared with existing technologies, this invention offers the following advantages: The molecularly anchored self-exfoliating copolymer chemically anchors the polydimethylsiloxane segments, reducing PDMS migration into the mold. Testing has shown that after 500 hours of continuous production, the silicon content on the mold surface is less than 0.01 ppm, significantly improving production continuity and making it suitable for applications requiring continuous production.

[0014] Reactive core-shell nanotougheners, with nanosilica as the core and an epoxy-containing polymer as the shell, help enhance the mechanical strength and toughness of the functional layer. By adjusting the dosage to 8-12 parts per part, the film can be tailored to the mechanical properties required for different application scenarios.

[0015] The asymmetric co-extrusion process, combined with a controlled micro-nanoprinting temperature of 145°C ± 3°C, a pressure of 15 MPa, and a chilling setting temperature of -10°C ± 2°C, facilitates the replication of the functional layer's micro-nanostructures. After 500 hours of continuous production, the structural replication fidelity exceeded 99%. The process also exhibits a reasonable tolerance for temperature fluctuations, facilitating industrial application.

[0016] The thickness ratio of the base layer to the functional layer is designed to be (4-5):1, and the thickness of the functional layer is 0.5-1.0μm. This structural design helps the film achieve better optical effects and wear resistance. Under some process conditions, more delicate micro-nano structures can be replicated, providing support for applications in anti-counterfeiting and other fields.

[0017] The molecular anchored self-exfoliating copolymer, reactive core-shell nano toughening agent and polyethylene wax in the enhanced functional material are compounded in a weight ratio of 80:(8-12):(8-12). This formula provides the possibility for cost optimization while ensuring the performance of the film, which is conducive to achieving a balance between performance and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Flowchart prepared for the present invention; DETAILED DESCRIPTION The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0019] Example 1 See Figure 1 This embodiment provides a method for preparing a CPP fantasy film, comprising the following steps: Step 1: prepare two core raw materials: first prepare a reactive core-shell nano toughening agent, ultrasonically disperse 100 parts by weight of nano-silica with a particle size of 15 nm in anhydrous toluene for 1 hour, dropwise add 5 parts by weight of γ-aminopropyltriethoxysilane and reflux at 110°C for 8 hours to obtain surface-activated nano-silica; then cool the activated nano-silica to 70°C, dropwise add a solution consisting of 40 parts of glycidyl laurate and 0.2 parts of an initiator, carry out graft polymerization at 85°C for 12 hours, purify and vacuum dry at 80°C for 24 hours to obtain a reactive core-shell nano toughening agent. -shell nano-toughening agent; secondly, a molecular anchoring self-exfoliating copolymer was prepared, and 100 parts of maleic anhydride grafted polypropylene and 10 parts of 1,6-hexanediamine were subjected to a ring-opening reaction in xylene at 130°C for 4 hours to obtain an amino-modified polypropylene intermediate; then the temperature was lowered to 90°C, 15 parts of epoxy-terminated polydimethylsiloxane were added dropwise, and the temperature was gradually increased to 120°C at a rate of 5°C / min, and the reaction was kept warm for 6 hours. After solvent recovery and granulation by a twin-screw extruder, a molecular anchoring self-exfoliating copolymer was obtained, and the grafting density of the polydimethylsiloxane chain segment was 1.2 mmol / g as determined by XPS.

[0020] Step 2, prepare enhanced functional materials: 80 parts by weight of the molecular anchored self-exfoliating copolymer prepared in step 1, 10 parts by weight of a reactive core-shell nano toughener, 10 parts by weight of a polyethylene wax additive, and 0.5 parts of auxiliary materials, antioxidant 1010, and a thermal stabilizer are compounded in a 1:1 ratio, pre-mixed at a high speed of 1500 rpm for 10 minutes, and then melt-blended and granulated through a twin-screw extruder at 170-200°C to obtain an enhanced functional material.

[0021] Step three, forming and preparing CPP fantasy color film: adopting an asymmetric co-extrusion process, the enhanced functional material of step two is used as the functional layer, and the cast-grade polypropylene resin is used as the base layer, and a composite film is formed by co-extrusion through a T-die, and the thickness ratio of the base layer to the functional layer is 4:1. The composite film with a thickness of 0.8μm is sequentially preheated by infrared with a wavelength of 3-5μm and a power density of 1.2W / cm², so that the interface temperature of the functional layer reaches 145℃ with an error of ±3℃, and enters the micro-nano imprinting unit with an imprinting pressure of 15MPa and a holding time of 8s; it is then immediately contacted with a chilled shaping roller at -10℃ with an error of ±2℃ to achieve non-destructive self-peeling of the composite film and the imprinting mold, and finally the CPP fantasy color film is obtained.

[0022] The CPP iridescent film prepared in this example features a functional layer containing a molecularly anchored self-exfoliating copolymer, a reactive core-shell nanotoughener, and a polyethylene wax additive. The molecular anchoring technology fundamentally prevents PDMS migration into the mold, ensuring the mold remains pristine even after over 500 hours of continuous production, eliminating the need for maintenance downtime. This significantly improves production efficiency and is particularly suitable for automotive interior panels, where continuous production is crucial. Furthermore, the introduction of the nanotoughener acts as a toughening agent within the functional layer, significantly enhancing its mechanical strength and fidelity.

[0023] Example 2 This example provides a method for preparing a CPP iridescent film and the CPP iridescent film produced by this method, which are substantially the same as those in Example 1, except that in step 2, the weight ratio of the reinforcing functional material is: 80 parts molecular anchoring self-exfoliating copolymer, 8 parts reactive core-shell nanotoughener, and 8 parts polyethylene wax additive. In step 3, when forming the CPP iridescent film, the thickness of the functional layer is controlled to be 0.6 μm, and the thickness ratio of the base layer to the functional layer is 4.5:1.

[0024] The CPP iridescent film prepared in this embodiment, due to the optimized ratio of toughening agent to auxiliary agent, can still ensure a structural replication fidelity of over 99% although the content of nano-toughening agent is slightly reduced. This formula combination not only ensures high-quality optical effects but also further reduces material costs, making it competitive in products that require high-security anti-counterfeiting labels but are more cost-sensitive, achieving an optimal balance between performance and cost.

[0025] Example 3 This embodiment provides a method for preparing a CPP iridescent film and the CPP iridescent film produced by this method, which are substantially the same as those in Example 1, except that in step 2, the weight ratio of the enhanced functional material is: 80 parts molecular anchoring self-exfoliating copolymer, 12 parts reactive core-shell nanotoughener, and 12 parts polyethylene wax additive. In step 3, when forming the CPP iridescent film, the thickness of the functional layer is controlled to be 1.0 μm, and the thickness ratio of the base layer to the functional layer is 5:1.

[0026] The CPP iridescent film prepared in this example maximizes the cohesive strength and self-peeling driving force of the functional layer by increasing the dosage of the reactive core-shell nanofiber toughener and polyethylene wax additive. The resulting iridescent film exhibits exceptional wear and scratch resistance, with a further reduction in peel force, ensuring stability even under ultra-high-speed production conditions, such as at speeds exceeding 20 m / min.

[0027] Example 4 The preparation method of a CPP iridescent film and the CPP iridescent film prepared by the method provided in this embodiment are basically the same as those in Example 1, except that: in step three, the interface temperature of the functional layer of the micro-nano imprinting is controlled at 142°C, and the imprinting pressure is 15 MPa; the temperature of the quenching and shaping is controlled at -8°C.

[0028] The CPP iridescent film produced in this example demonstrates the stability of this technical solution within a wide process window through fine-tuning of process parameters. Even under non-optimal temperature settings, the core raw materials exhibit excellent performance, with structural replication fidelity remaining above 99% and minimal peel force fluctuation. This high tolerance to production line environmental fluctuations reduces the demanding requirements for precise equipment control.

[0029] Example 5 The preparation method of a CPP iridescent film and the CPP iridescent film prepared by the method provided in this embodiment are basically the same as those in Example 1, except that: in step three, the interface temperature of the micro-nano imprinted functional layer is controlled at 148°C, and the imprinting pressure is 15 MPa; the quenching and shaping temperature is controlled at -12°C.

[0030] The CPP iridescent film prepared in this example exhibits enhanced functional layer fluidity at slightly elevated processing temperatures, enabling the replication of intricate micro- and nanostructures, such as line widths <300nm. The resulting iridescent film exhibits vibrant, dynamic color-changing effects. This characteristic enables it to create visual barriers and provide security in anti-counterfeiting applications such as documents, bills, and brand protection labels.

[0031] Example 6 This example provides a method for preparing a CPP iridescent film and the CPP iridescent film prepared by the method. The method is essentially the same as that of Example 1, except that in step 1, when preparing the reactive core-shell nanofiber toughening agent, the amount of silane coupling agent γ-aminopropyltriethoxysilane used is 3% (i.e., 3 parts by weight) of the mass of the nano-silicon dioxide. The remaining raw material ratios and process parameters are the same as those of Example 1. Example 7 This example provides a method for preparing a CPP iridescent film and the CPP iridescent film prepared by the method. The method is substantially the same as that of Example 1, except that in step 1, when preparing the reactive core-shell nanofiber toughening agent, the amount of silane coupling agent γ-aminopropyltriethoxysilane used is 8% (i.e., 8 parts by weight) of the mass of the nano-silicon dioxide. The remaining raw material ratios and process parameters are the same as those of Example 1. Comparative Example 1 The traditional process is used, that is, PET release film is co-extruded with CPP substrate, and then hot pressing transfer is performed to replicate the micro-nano structure.

[0032] Comparative Example 2 The preparation method is basically the same as that of Example 1, except that in step 2, no reactive core-shell nanotoughener is added, and only the molecular anchoring self-exfoliating copolymer and PE wax are used to prepare the functional layer.

[0033] Comparative Example 3 The preparation method is basically the same as that of Example 1, except that in step 1, a molecular anchored self-exfoliating copolymer is not prepared, but a simple PP / PDMS / PE wax blend is used instead.

[0034] In the examples and comparative examples: nano-silica was purchased from Hangzhou Haina Optoelectronics Environmental Protection Technology Co., Ltd.; silane coupling agent was purchased from Nanjing Chuangshi Chemical Technology Co., Ltd.; maleic anhydride grafted polypropylene was purchased from Kingfa Technology Co., Ltd.; diamine was purchased from Shandong Haihua Group Co., Ltd.; epoxy-terminated polydimethylsiloxane was purchased from Hubei New Blue Sky New Materials Co., Ltd.; polyethylene wax was purchased from Qingdao Bangni Chemical Co., Ltd.; antioxidant was purchased from Beijing Jiyi Chemical Co., Ltd.; cast-grade polypropylene resin was purchased from China Petrochemical Corporation.

[0035] In order to objectively evaluate the comprehensive performance of the CPP iridescent film of the present invention and verify the effects under different combinations of process parameters, the CPP iridescent films prepared in Examples 1-7 and Comparative Examples 1-3 were subjected to tensile performance tests to evaluate their mechanical strength and toughness, which are directly related to the reliability of the film during processing and use.

[0036] To simulate the performance of real industrial production environments and final products in application scenarios, all samples were tested for tensile strength and structural replication fidelity after 500 hours of continuous production. This assessment evaluated the mechanical strength and toughness of the membrane, which are directly related to processing and reliability. The test method referenced standard GB / T 13022-91, with a tensile speed of 250±25mm / min. Samples were taken after 500 hours of continuous production, and atomic force microscopy was used to examine the integrity of the micro-nanostructure to characterize long-term production stability and durability. After 500 hours of continuous production, XPS was used to detect residual silicon on the surface of the imprint mold to characterize the migration contamination of PDMS. Table 1: Comparison of comprehensive performance of CPP iridescent films prepared by different schemes The following conclusions can be drawn from the comprehensive data in Table 1: After 500 hours, the silicon content on the mold surface in all Examples 1-7 remained below the detection limit of <0.01ppm, in stark contrast to the >50ppm found in Comparative Example 3. This strongly demonstrates the effectiveness of the molecularly anchored, self-exfoliating copolymer, which firmly binds the PDMS segments through chemical bonds, fundamentally resolving mold contamination issues and laying the foundation for long-term, stable production. After 500 hours of continuous production, all Examples 1-7 maintained structural replication fidelity above 99.1%, far exceeding all comparative examples; the former ensures mold cleanliness, while the latter provides sufficient mechanical strength to withstand prolonged physical wear.

[0037] The tensile strength of 12 parts of toughening agent in Example 3 is the highest, 52.8 MPa, while that of 8 parts of toughening agent in Example 2 is relatively low, 45.2 MPa. This shows that by adjusting the amount of nano-toughening agent, the mechanical properties of the film can be customized as needed to adapt to different application scenarios. For example, Example 3 is suitable for highly wear-resistant AR / VR components, and Example 2 is suitable for cost-sensitive anti-counterfeiting labels.

[0038] Examples 4 and 5 were produced at suboptimal process temperatures. Their final properties, such as tensile strength and fidelity, were slightly lower than those of Example 1, which achieved the optimal temperature, but superior to all comparative examples. This demonstrates that the process of the present invention is highly tolerant to environmental fluctuations on the production line and is amenable to industrial application. Example 5 achieved slightly higher fidelity at a slightly higher temperature, indicating that these process parameters facilitate the replication of finer structures. Although the coupling agent content in Example 6 was reduced, the surface activation of the nano-silica was still sufficient, the grafting rate of the functional layer was >95%, and the fidelity reached 99.0%; The higher dosage in Example 7 did not lead to agglomeration of the nanoparticles (TEM showed uniform dispersion), and due to the increase in surface active sites, the tensile strength was increased to 47.9 MPa. Comparative Example 1: Due to process limitations, the physical peeling force was large and thermal stress damage was severe, making high-fidelity and long-cycle production impossible. Comparative Example 2: Although the contamination problem was solved and the silicon content was <0.01ppm, the mechanical properties were weak, with a tensile strength of only 29.8MPa. During long-term production, physical wear caused the fidelity to drop significantly to 82.3%. Comparative Example 3: Due to large-scale migration of PDMS and severe mold contamination, the fidelity dropped sharply to 75.0% after 500 hours. The tensile strength was also reduced due to the plasticization effect of PDMS, and the product was completely incapable of stable production. The present invention solves the two major problems of dynamic contradiction of interface adhesion and thermal stress mismatch in the manufacture of CPP fantasy color film through the synergistic effect of two materials and optimization of the process flow, realizes continuous and stable production, lossless and high-fidelity molding, and improves product performance.

[0039] Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A method for preparing a CPP fantasy film, characterized in that: The following steps are involved: Step 1: Prepare two core raw materials: Preparation of a reactive core-shell nano toughening agent: Ultrasonic dispersion of nano-silica in a solvent, addition of a silane coupling agent, and reflux reaction to obtain surface-activated nano-silica; Mixing the activated nano-silica with a solution containing glycidyl laurate and an initiator, performing a graft polymerization reaction, and obtaining the reactive core-shell nano toughening agent after purification and drying; Preparation of a molecular anchored self-exfoliating copolymer: Maleic anhydride grafted polypropylene and a diamine undergo a ring-opening reaction in a solvent to obtain an amino-modified polypropylene intermediate; Adding epoxy-terminated polydimethylsiloxane to the intermediate, performing a graft reaction by gradient temperature increase, and obtaining the molecular anchored self-exfoliating copolymer after solvent recovery and granulation; Step 2: preparing an enhanced functional material: pre-mixing the reactive core-shell nano toughening agent, the molecular anchoring self-exfoliating copolymer, the polyethylene wax and the auxiliary materials prepared in step 1 at high speed, then melt-blending them through a twin-screw extruder, and extruding and granulating them to obtain an enhanced functional material; Step three, forming and preparing CPP fantasy color film: adopting an asymmetric co-extrusion process, the enhanced functional material is used as the functional layer, and the cast-grade polypropylene resin is used as the base layer, and a composite film is formed by co-extrusion through a T-die; the composite film is subjected to infrared preheating, micro-nano imprinting and chilling shaping in sequence, and the micro-nano structure is replicated on the surface of the functional layer, and the composite film and the imprinting mold are non-destructively peeled off, and finally the CPP fantasy color film is obtained.

2. The method according to claim 1, characterized in that The particle size of the nano-silica is 15 nm; the silane coupling agent is γ-aminopropyltriethoxysilane; and the temperature of the reflux reaction is 110°C.

3. The method according to claim 1, characterized in that The temperature of the ring-opening reaction is 130°C; the insulation reaction temperature of the grafting reaction is 120°C.

4. The method or CPP magic color film according to any one of claim 2, characterized in that: The weight ratio of the enhanced functional material, the molecular anchoring self-stripping copolymer, the reactive core-shell nano toughening agent, and the polyethylene wax additive is 80:(8-12):(8-12).

5. The method according to claim 1, wherein The interface temperature of the functional layer of the micro-nano imprinting is controlled at 145°C ± 3°C, and the imprinting pressure is 15 MPa; the temperature of the quenching and shaping is controlled at -10°C ± 2°C.

6. A CPP fantasy color film, characterized in that: Its structure includes: a base layer: composed of cast-grade polypropylene resin; a functional layer: compounded on the base layer and having a micro-nano structure, the functional layer is composed of the following components: (a) Molecular anchored self-exfoliating copolymer: the reaction product of maleic anhydride grafted polypropylene, 1,6-hexanediamine, and epoxy-terminated polydimethylsiloxane; (b) Reactive core-shell nanotougheners: They have a core-shell structure with nano-silica as the core and a polymer containing epoxy groups as the shell; (c) Polyethylene wax additive.

7. The CPP fantasy film according to claim 6, characterized in that: The thickness ratio of the base layer to the functional layer is (4-5):

1.

8. The CPP fantasy film according to any one of claim 6, characterized in that: The thickness of the functional layer is 0.5-1.0 μm.

9. The CPP fantasy film according to claim 6, characterized in that: The grafting density of the polydimethylsiloxane segments in the molecular anchoring self-exfoliating copolymer is 1.2 mmol / g.

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