High-temperature-resistant injection-molded aluminum gold-glittering flash powder and preparation method thereof

Abstract

This invention relates to the field of polymer materials technology, specifically to a high-temperature resistant aluminum glitter powder for injection molding and its preparation method. The glitter powder comprises a roughened aluminum foil substrate, a silane coupling agent interface bridging layer, and a double-sided cross-linked cellulose protective coloring layer. The preparation method includes: micro-etching the aluminum foil in a two-step process using an alkaline solution and a phosphoric acid / sodium chloride mixture to form a micro-roughened structure; pre-treating and bonding the aluminum foil with a KH-560 ethanol solution to form an interface bridging layer; coating the aluminum foil with a slurry containing cellulose acetate propionate, nano-cellulose microfilaments, citric acid, pentaerythritol, and sodium hypophosphite; and rapidly cross-linking the slurry at 190-210℃ for 4-6 minutes. This invention achieves molecular-level chemical bonding between the inorganic aluminum foil and the organic cross-linked network through a stepwise chemical anchoring process, specific micro-roughening treatment, and a precise 2:1 ratio of citric acid to pentaerythritol. The resulting glitter powder exhibits strong interfacial bonding, high-temperature resistance to yellowing and oxidation, and low gas generation and pitting during injection molding, making it widely applicable in high-temperature injection molded products at 250-300℃.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a high-temperature resistant aluminum glitter powder for injection molding and its preparation method. Background Technology

[0002] Glitter powder (also known as glitter powder) is widely used in the decoration of plastic products such as cosmetic packaging, automotive interiors, toys, and appliance casings due to its unique metallic luster and shimmering visual effect. Injection molding after mixing glitter powder with plastic raw materials is a highly efficient processing method to achieve a lasting glitter effect on the surface of the product. However, the injection molding process places extremely stringent performance requirements on the added powder materials, with high-temperature resistance being the most critical challenge. Commonly used powders include cellulose-based glitter powder and aluminum-based glitter powder, with cellulose-based glitter powder being more commonly used in low-temperature applications.

[0003] However, aluminum glitter faces three major technical challenges in high-temperature injection molding applications: First, insufficient interfacial bonding between the aluminum foil and the organic protective layer. During injection molding, the high shear force of the high-temperature melt (typically 250-300℃) easily causes the organic protective coating to peel off from the aluminum foil surface, resulting in the glitter losing its protection and oxidizing and turning black. Simultaneously, the detached coating fragments form visible defects on the surface of the injection-molded part. Second, the extremely thin aluminum layer (typically 6-10μm) has extremely poor oxidation resistance in high-temperature, oxygen-containing environments. At the high temperatures of injection molding, oxygen can penetrate the organic protective layer and reach the aluminum surface, causing the aluminum layer to rapidly oxidize into aluminum oxide, leading to a sharp decrease in gloss or even complete loss of luster. Third, traditional cross-linking protective systems are prone to thermal degradation and yellowing during prolonged high-temperature curing, affecting the color purity and transparency of the glitter.

[0004] Therefore, there is an urgent need in this field for a high-temperature resistant aluminum glitter powder that can achieve a more stable interface under high-temperature injection molding conditions and its preparation method. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide a high-temperature resistant aluminum glitter powder for injection molding and its preparation method, thereby solving the problem of easy decomposition of the coating of glitter powder during high-temperature injection molding in the prior art.

[0006] To achieve the above-mentioned technical effects, the present invention adopts the following technical solution: In a first aspect, the present invention provides a high-temperature resistant aluminum glitter powder, the glitter powder comprising a roughened aluminum foil substrate, a silane coupling agent interface bridging layer, and a double-sided cross-linked cellulose protective coloring layer.

[0007] The silane coupling agent interface bridging layer is formed by pretreating and bonding γ-glycidyl ether oxypropyltrimethoxysilane (KH-560) to both sides of a pretreated aluminum foil. The double-sided cross-linked cellulose protective coloring layer is coated on the outside of the silane coupling agent interface bridging layer. The double-sided cross-linked cellulose protective coloring layer is formed by cross-linking and curing a slurry containing the following components in parts by weight: 18-22 parts of cellulose acetate propionate, 2-4 parts of nanocellulose microfilaments, 3-5 parts of citric acid, 1.5-2.5 parts of pentaerythritol, 0.5-1.2 parts of sodium hypophosphite, 0.5-2 parts of high-temperature resistant color powder, and 65-75 parts of mixed solvent.

[0008] Preferably, the mixed solvent is a mixture of ethanol and acetone.

[0009] Preferably, the high-temperature resistant pigment is selected from at least one of the following: Red 40 aluminum lake (CI 16035, CAS 25956-17-6, INCI: FD&C RED 40 AI LAKE), Red 27 aluminum lake (CI 45410, CAS 15876-58-1, INCI: D&C RED 27 AI LAKE), Red 7 calcium lake (CI 15850, CAS 5281-04-9, INCI: D&C RED 7 Ca LAKE), Black 2 (CI 77266, CAS 1333-86-4, INCI: D&C BLACK 2), Yellow 5 aluminum lake (CI 19140, CAS 1934-21-0, INCI: FD&C YELLOW 5 LAKE), and Blue 1 aluminum lake (CI 42090, CAS 3844-45-9, INCI: FD&C BLUE 1AI LAKE) or titanium dioxide (CI 77891, CAS 13463-67-7, INCI: Titanium Dioxide) Preferably, the weight ratio of citric acid to pentaerythritol is 2:1. When the weight ratio of citric acid to pentaerythritol is controlled at 2:1, the molar ratio of carboxyl groups to hydroxyl groups is close to the stoichiometric ratio, which enables the formation of a dense three-dimensional polyester network under extremely rapid crosslinking conditions, while reducing the residue of unreacted small molecules.

[0010] Preferably, the thickness of the roughened aluminum foil substrate is 6-10 μm, and the surface of the roughened aluminum foil substrate is treated with an alkaline solution and a phosphoric acid / sodium chloride mixture to form a micron-level rough structure; the alkaline solution is a 0.8-1.2 mol / L sodium hydroxide solution, and the treatment time is 10-20 s; the phosphoric acid concentration in the phosphoric acid / sodium chloride mixture is 0.1-0.3 mol / L, the sodium chloride concentration is 0.5-1.0 mol / L, and the treatment time is 25-35 s. This two-step micro-etching process constructs a micro-rough structure that increases the specific surface area of ​​the aluminum foil, providing more reaction sites for the subsequent bonding of the silane coupling agent, while also enhancing the mechanical adhesion between the coating and the substrate.

[0011] Preferably, the silane coupling agent interfacial bridging layer is formed by uniformly coating both sides of the pretreated aluminum foil with a KH-560 ethanol solution of 0.8-1.2% by mass and drying it at 75-85℃ for 4-6 minutes. This invention employs a stepwise pretreatment process, first completing the condensation bonding between the siloxane and the aluminum foil in an interference-free ethanol system, causing the siloxane groups to undergo a condensation reaction with the hydroxyl groups on the aluminum foil surface. This results in the formation of an oriented monolayer of epoxy groups on the aluminum foil surface, providing a chemical bonding basis for subsequent crosslinking.

[0012] Preferably, the single-sided dry film thickness of the double-sided cross-linked cellulose protective coloring layer is 3-5 μm. This thickness range ensures sufficient oxygen barrier effect without reducing flexibility or causing edge delamination during cutting due to excessive coating thickness.

[0013] Preferably, the crosslinking curing conditions are: temperature 190-210℃, time 4-6 min.

[0014] Preferably, the high-temperature resistant aluminum glitter powder is hexagonal in shape and has a particle size of 0.1-0.3 mm.

[0015] Secondly, the present invention provides a method for preparing the above-mentioned high-temperature resistant aluminum glitter powder, the method comprising the following steps: S1: Aluminum foil micro-roughening: After ultrasonic cleaning with organic solvent, aluminum foil is immersed in alkaline solution, washed with water, then immersed in a mixture of phosphoric acid / sodium chloride solution, washed with water and dried to obtain pretreated aluminum foil; S2: Interface bridging pretreatment: KH-560 ethanol solution is evenly coated on both sides of the pretreated aluminum foil and then dried; S3: Double-sided coating: A slurry containing cellulose acetate propionate, nanocellulose microfilaments, citric acid, pentaerythritol, sodium hypophosphite, high-temperature resistant pigments and mixed solvents is uniformly coated on both sides of the aluminum foil treated by S2. S4: Thermal crosslinking: The coated aluminum foil is sent into a high-temperature drying tunnel for crosslinking and curing; S5: Precision cutting and sieving: After cooling, the product is cut into the set shape to obtain the finished product.

[0016] Preferably, in step S1, the aluminum foil thickness is 6-10 μm; the alkaline solution is a 0.8-1.2 mol / L sodium hydroxide solution, and the treatment time is 10-20 s; the phosphoric acid / sodium chloride mixture contains 0.1-0.3 mol / L phosphoric acid and 0.5-1.0 mol / L sodium chloride, and the treatment time is 25-35 s.

[0017] Preferably, in step S2, the mass concentration of the KH-560 ethanol solution is 0.8-1.2%, the drying temperature is 75-85℃, and the drying time is 4-6 min; in step S4, the crosslinking curing temperature is 190-210℃, and the time is 4-6 min.

[0018] Thirdly, the present invention provides an application of the above-mentioned high-temperature resistant aluminum glitter powder in injection molded products, wherein the processing temperature of the injection molded products is 250-300℃.

[0019] The beneficial effects of this invention are as follows: First, this invention employs a two-step micro-etching process using an alkaline solution and a mixture of phosphoric acid / sodium chloride to construct a micro-rough structure, providing ample reaction sites and physical interlocking force for chemical anchoring. Cellulose acetate propionate is selected as the film-forming substrate, which exhibits superior heat degradation resistance compared to conventional cellulose acetate. Combined with the physical reinforcement and gas barrier effects of nanocellulose microfilaments, the structural stability and protective performance of the coating at high temperatures are further enhanced.

[0020] Secondly, this invention employs a stepwise chemical anchoring process, improving upon the conventional method of internally adding coupling agents. In step S2, KH-560 is pretreated and bonded to the surface of the pretreated aluminum foil in an interference-free ethanol system, forming a monolayer with oriented epoxy groups. In step S4, during crosslinking, the exposed epoxy groups undergo ring-opening and esterification with citric acid under sodium hypophosphite catalysis, achieving molecular-level chemical bonding between the inorganic aluminum foil and the organic crosslinking network. This significantly improves the interfacial bonding force under high temperature and high shear conditions, preventing coating delamination.

[0021] Finally, in this process, the present invention rapidly constructs a dense three-dimensional polyester network by controlling the weight ratio of citric acid to pentaerythritol to 2:1 and performing rapid crosslinking under the catalysis of sodium hypophosphite. This ratio ensures that the molar ratio of carboxyl groups to hydroxyl groups is close to the stoichiometric ratio, which not only guarantees the density of the crosslinked network to provide an effective gas-tight barrier, significantly reducing oxygen permeation and aluminum foil oxidation and blackening at high temperatures, but also reduces the residue of unreacted small molecules and lowers the rate of gas generation and pitting during injection molding. At the same time, the rapid crosslinking process effectively shortens the high-temperature heating time, reducing the risk of yellowing of the substrate. Attached Figure Description

[0022] Figure 1 This is a photograph of the injection-molded high-temperature resistant aluminum glitter powder prepared in Example 1 of the present invention. Detailed Implementation

[0023] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the technical solution of the present invention and are therefore intended to limit the scope of protection of the present invention.

[0024] Example 1

[0025] This embodiment provides a high-temperature resistant aluminum glitter powder, the preparation method of which includes the following steps: S1: Aluminum foil micro-roughening: Take an 8μm thick aluminum foil, ultrasonically clean it with acetone for 10min to remove surface oil, immerse it in 1.0 mol / L NaOH solution for 15s, and rinse it with deionized water; then immerse it in a mixed solution containing 0.2 mol / L phosphoric acid and 0.75 mol / L sodium chloride for 30s, rinse it with deionized water, and dry it at 60℃ to obtain pretreated aluminum foil.

[0026] S2: Interface bridging pretreatment: A 1% KH-560 ethanol solution is uniformly roller-coated onto both sides of the pretreated aluminum foil and dried at 80℃ for 5 min. This allows the siloxane groups of KH-560 to undergo a condensation reaction with the hydroxyl groups on the aluminum foil surface to form Si-O-Al bonds, and the epoxy groups to align outwards, forming an interface bridging layer.

[0027] S3: Double-sided coating: Prepare component B slurry, the formula of which is: 20 parts by weight of cellulose acetate propionate (CAP), 3 parts by weight of nanocellulose microfilaments, 4 parts by weight of citric acid (CA), 2 parts by weight of pentaerythritol (PER), 0.8 parts by weight of sodium hypophosphite (SHP), 1 part by weight of titanium dioxide (CAS 13463-67-7) high-temperature resistant pigment, and 70 parts by weight of mixed solvent (ethanol / acetone, volume ratio 1:1). After the above components are mixed evenly, they are uniformly coated on both sides of the aluminum foil treated in S2, and the dry film thickness on one side is controlled to be 4 μm.

[0028] S4: Rapid thermal crosslinking: The coated aluminum foil is placed in a high-temperature drying tunnel and crosslinked at 200℃ for 5 minutes. During the crosslinking process, the epoxy groups introduced in S2 undergo ring-opening under SHP catalysis and esterify with the carboxyl groups of CA in component B, realizing the chemical bonding between the inorganic aluminum foil and the organic crosslinking network; at the same time, CA and PER undergo esterification under SHP catalysis to form a dense three-dimensional polyester network.

[0029] S5: Precision cutting and sieving: After cooling, it is cut into 0.2mm hexagons to obtain the high-temperature resistant aluminum glitter powder product. Figure 1 As shown.

[0030] Example 2

[0031] The only difference between this embodiment and Example 1 is that in step S2, the mass concentration of the KH-560 ethanol solution is 0.8%, the drying temperature is 75°C, and the drying time is 6 min; in step S4, the crosslinking temperature is 190°C and the time is 6 min. All other components and process parameters are the same as in Example 1.

[0032] Example 3

[0033] The only difference between this embodiment and Example 1 is that: in step S2, the mass concentration of the KH-560 ethanol solution is 1.2%, the drying temperature is 85°C, and the drying time is 4 min; in step S4, the crosslinking temperature is 210°C and the time is 4 min. All other components and process parameters are the same as in Example 1.

[0034] Comparative Example 1 The only difference between this comparative example and Example 1 is that step S2 is removed, KH-560 pretreatment is not performed, and component B slurry is directly coated on the pretreated aluminum foil. All other process parameters are the same as in Example 1.

[0035] Comparative Example 2 The only difference between this comparative example and Example 1 is that the S2 pretreatment step is omitted, and an equal amount of KH-560 is directly incorporated into the B component slurry (i.e., the coupling agent is mixed and coated together with other components of the slurry). All other process parameters are the same as in Example 1.

[0036] Comparative Example 3 The only difference between this comparative example and Example 1 is that in step S2, KH-560 is replaced with an equal amount of KH-550 (γ-aminopropyltriethoxysilane), while the other process parameters are the same as in Example 1.

[0037] Comparative Example 4 The only difference between this comparative example and Example 1 is that in step S2, KH-560 is replaced with an equal amount of KH-570 (γ-methacryloyloxypropyltrimethoxysilane), while the other process parameters are the same as in Example 1.

[0038] Comparative Example 5 The only difference between this comparative example and Example 1 is that the citric acid in component B slurry is 4 parts by weight and the pentaerythritol is 0.5 parts by weight (CA:PER=8:1). All other components and process parameters are the same as in Example 1.

[0039] Comparative Example 6 The only difference between this comparative example and Example 1 is that the citric acid in component B slurry is 4 parts by weight and the pentaerythritol is 1 part by weight (CA:PER=4:1). All other components and process parameters are the same as in Example 1.

[0040] Comparative Example 7 The only difference between this comparative example and Example 1 is that the citric acid in component B slurry is 4 parts by weight and the pentaerythritol is 4 parts by weight (CA:PER=1:1). All other components and process parameters are the same as in Example 1.

[0041] Comparative Example 8 The only difference between this comparative example and Example 1 is that the micro-roughening treatment in S1 is omitted, and S2 and subsequent steps are performed directly on the original smooth aluminum foil that has been ultrasonically cleaned with acetone. All other components and process parameters are the same as in Example 1.

[0042] Comparative Example 9 The only difference between this comparative example and Example 1 is that in S1, only the NaOH solution treatment is performed, and the subsequent phosphoric acid / sodium chloride mixed solution treatment is not performed. The other components and process parameters are the same as in Example 1.

[0043] Comparative Example 10 The only difference between this comparative example and Example 1 is that sodium hypophosphite (SHP) is not added to the B component slurry; all other components and process parameters are the same as in Example 1.

[0044] Comparative Example 11 The only difference between this comparative example and Example 1 is that: no nanocellulose microfilaments are added to the B component slurry, and the amount of cellulose acetate propionate is increased to 23 parts by weight to maintain a consistent solid content. All other components and process parameters are the same as in Example 1.

[0045] Comparative Example 12 The only difference between this comparative example and Example 1 is that cellulose acetate propionate (CAP) in component B slurry is replaced with an equal amount of conventional cellulose acetate (CA), while the other components and process parameters are the same as in Example 1.

[0046] Test case The glitter powders prepared in the above embodiments and comparative examples were subjected to the following performance tests: Crosslinking degree (%): The sample was first immersed in 1 mol / L dilute hydrochloric acid to remove the aluminum foil substrate. The remaining organic coating film was collected, washed, dried, and weighed as the initial sample (W1). The initial sample was then immersed in 50 mL of acetone, refluxed at 80 °C for 4 h, filtered, dried, and weighed (W2). Crosslinking degree = (W2 / W1) × 100%.

[0047] (2) Yellowing index (ΔE): Take flat cross-linked coated aluminum foil without slitting step, and use a colorimeter to measure its color values ​​(L*, a*, b*) before and after static treatment at 300℃, and calculate the color difference ΔE between the two.

[0048] (3) Adhesion / Delamination rate (%): 0.5g of glitter powder was placed in PA66 melt at 280℃ and stirred for 30s. After filtration and cleaning, 100 intact particles were randomly selected to prepare cross sections. The cross sections were observed using a scanning electron microscope (SEM) and the number of particles that showed obvious separation between the coating and the aluminum foil was counted.

[0049] Delamination rate = (number of delaminated particles / 100) × 100%. This indicator assesses the anchoring strength of the interface under high temperature and high shear conditions.

[0050] (4) Static oxidation resistance at 300℃ (gloss retention rate %): Take a flat cross-linked coated aluminum foil without slitting and measure its initial gloss; then place it in a muffle furnace and treat it in air at 300℃ for 1 hour. After cooling, measure the gloss at the same location again.

[0051] Gloss retention rate = (gloss after aging / initial gloss) × 100%; (5) Injection molding air-pumping pit rate (number / dm) 2 Add 3wt% glitter powder to fully dried PA66 resin, and injection mold standard samples at 280℃. Randomly select 10 samples of 1dm. 2 In the area, the number of raised pits caused by gas evaporation on the surface was counted, and the average value was taken.

[0052] The specific test results are shown in Table 1.

[0053] Table 1 Performance test results for each group Example 1 94.5 1.2 3 98.7 0 Example 2 93.2 1.4 6 96.9 1 Example 3 93.8 1.5 5 97.4 0 Comparative Example 1 92.5 6.8 45 55.9 17 Comparative Example 2 87.6 5.6 38 68.2 25 Comparative Example 3 45.6 14.2 22 42.5 >200 Comparative Example 4 91.2 6.5 37 62.1 12 Comparative Example 5 58.6 15.4 15 60.5 48 Comparative Example 6 82.4 4.8 8 85.2 9 Comparative Example 7 76.5 8.6 12 75.4 92 Comparative Example 8 94.3 3.9 32 82.1 5 Comparative Example 9 93.6 5.1 25 88.6 2 Comparative Example 10 35.2 18.5 53 30.2 126 Comparative Example 11 92.8 3.4 15 78.5 5 Comparative Example 12 85.4 8.8 18 70.4 27 As shown in Table 1, the high-temperature resistant aluminum glitter powder provided by the present invention adopts a specific stepwise chemical anchoring process and crosslinking system ratio. The prepared sample shows excellent comprehensive performance in terms of crosslinking degree, high-temperature yellowing resistance, high-temperature shear delamination rate, high-temperature gloss retention rate and injection molding pitting rate.

[0054] A comparison of Example 1 with Comparative Examples 1 and 2 shows that the addition process of KH-560 has a significant impact on interfacial bonding and overall performance. Comparative Example 1, without using any coupling agent, exhibited a high-temperature shear delamination rate as high as 45%, and a gloss retention rate reduced to 55.9%. Comparative Example 2, using an internal doping method to add KH-560, saw its crosslinking degree decrease to 87.6%, its delamination rate to 38%, and its gloss retention rate to only 68.2%. In contrast, Example 1, employing the S2 pretreatment step of this invention, achieved a delamination rate reduced to 3%, while maintaining optimal crosslinking degree and gloss retention rate. This indicates that the stepwise pretreatment process plays a crucial role in improving interfacial bonding.

[0055] The comparison between Example 1 and Comparative Examples 3 and 4 shows that the choice of coupling agent has a significant impact on the crosslinking system and interfacial bonding. Comparative Example 3 used KH-550, which significantly reduced the degree of crosslinking to 45.6%, increased the yellowing index to 14.2, and resulted in an excessive injection molding pitting rate (>200 pits / dm²). 2 Comparative Example 4 used KH-570, with a crosslinking degree of 91.2%, but the delamination rate was as high as 37%, and the gloss retention rate was only 62.1%. The above data comparison shows that KH-560 exhibits the best synergistic effect in the crosslinking system of the present invention.

[0056] The comparison between Example 1 and Comparative Examples 5, 6, and 7 shows that the ratio of citric acid to pentaerythritol has a significant impact on the crosslinking network structure and final properties. In Comparative Example 5, pentaerythritol was severely insufficient (CA:PER = 8:1), resulting in a crosslinking degree of only 58.6%, a gloss retention rate as low as 60.5%, and a pitting rate as high as 48 pits / dm². 2 In Comparative Example 6, pentaerythritol was slightly insufficient (CA:PER = 4:1), resulting in a crosslinking degree of 82.4%, and both the delamination rate and the pinhole rate were higher than in Example 1. In Comparative Example 7, pentaerythritol was excessive (CA:PER = 1:1), causing the crosslinking degree to decrease to 76.5% and the pinhole rate to increase to 92 pinholes / dm². 2 The above results indicate that controlling the weight ratio of citric acid to pentaerythritol at 2:1 is a key condition for achieving high crosslinking degree, high oxygen barrier properties, and low gas production rate.

[0057] The comparison between Example 1 and Comparative Examples 8 and 9 shows that the micro-roughening treatment of the aluminum foil surface is crucial to the interfacial adhesion. Comparative Example 8, without micro-roughening treatment, achieved a cross-linking degree of 94.3%, but the delamination rate increased to 32%. Comparative Example 9, undergoing only alkaline etching, achieved a delamination rate of 25% and a yellowing index of 5.1. The results indicate that the two-step micro-etching process using an alkaline solution and a phosphoric acid / sodium chloride mixture employed in this invention can more effectively improve interfacial stability under high temperature and high shear conditions.

[0058] The comparison between Example 1 and Comparative Example 10 shows that sodium hypophosphite (SHP) is indispensable in the crosslinking system. Comparative Example 10, without the addition of SHP, had a crosslinking degree of only 35.2%, a delamination rate as high as 53%, severe yellowing at 300°C (ΔE=18.5), and extremely low gloss retention. The results indicate that under extremely rapid thermal crosslinking conditions, SHP is a necessary condition for the formation of a dense crosslinked network and interfacial chemical bonding.

[0059] The comparison between Example 1 and Comparative Example 11 shows that nanocellulose microfilaments enhance the barrier properties and adhesion of the coating. Comparative Example 11, without the addition of nanocellulose microfilaments, maintained essentially the same degree of crosslinking (92.8%), but its delamination rate increased to 15%, and its gloss retention decreased to 78.5%. These results indicate that the addition of nanocellulose microfilaments helps improve the overall protective performance of the coating at high temperatures.

[0060] The comparison between Example 1 and Comparative Example 12 shows that the choice of film-forming resin has a significant impact on high-temperature resistance. In Comparative Example 12, replacing cellulose acetate propionate (CAP) with conventional cellulose acetate (CA) resulted in a decrease in crosslinking degree to 85.4%, a yellowing index as high as 8.8, and significant delamination and pitting rates. The results indicate that CAP exhibits better structural stability and compatibility under high-temperature crosslinking and injection molding conditions.

[0061] As can be seen from the overall results of Examples 1-3, within the range of process parameters defined by the present invention, each example exhibits excellent comprehensive performance, confirming that the technical solution of the present invention has good process tolerance.

[0062] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention. Technical aspects, shapes, and structures not described in detail in this invention are all well-known technologies.

Claims

1. A high-temperature resistant aluminum glitter powder, characterized in that, The glitter powder comprises a roughened aluminum foil substrate, a silane coupling agent interface bridging layer, and a double-sided cross-linked cellulose protective coloring layer; wherein, the silane coupling agent interface bridging layer is formed by pretreating and bonding γ-glycidyl ether oxypropyltrimethoxysilane (KH-560) to both sides of the pretreated aluminum foil, and the double-sided cross-linked cellulose protective coloring layer covers the outside of the silane coupling agent interface bridging layer; the double-sided cross-linked cellulose protective coloring layer is formed by cross-linking and curing a slurry containing the following components in parts by weight: 18-22 parts of cellulose acetate propionate, 2-4 parts of nanocellulose microfilaments, 3-5 parts of citric acid, 1.5-2.5 parts of pentaerythritol, 0.5-1.2 parts of sodium hypophosphite, 0.5-2 parts of high-temperature resistant pigment, and 65-75 parts of mixed solvent.

2. The high-temperature resistant aluminum glitter powder according to claim 1, characterized in that, The weight ratio of citric acid to pentaerythritol is 2:

1.

3. The high-temperature resistant aluminum glitter powder according to claim 1, characterized in that, The thickness of the roughened aluminum foil substrate is 6-10 μm. The surface of the roughened aluminum foil substrate is treated with an alkaline solution and a mixture of phosphoric acid / sodium chloride to form a micron-level rough structure. The alkaline solution is a 0.8-1.2 mol / L sodium hydroxide solution, and the treatment time is 10-20 s. The phosphoric acid concentration in the phosphoric acid / sodium chloride mixture is 0.1-0.3 mol / L, the sodium chloride concentration is 0.5-1.0 mol / L, and the treatment time is 25-35 s.

4. The high-temperature resistant aluminum glitter powder according to claim 1, characterized in that, The silane coupling agent interface bridging layer is formed by uniformly coating a KH-560 ethanol solution with a mass concentration of 0.8-1.2% onto both sides of the pretreated aluminum foil and drying it at 75-85℃ for 4-6 minutes.

5. The high-temperature resistant aluminum glitter powder according to claim 1, characterized in that, The thickness of the single-sided dry film of the double-sided cross-linked cellulose protective coloring layer is 3-5 μm; the cross-linking curing conditions are: temperature 190-210℃, time 4-6 min.

6. The high-temperature resistant aluminum glitter powder according to claim 1, characterized in that, The mixed solvent is a mixture of ethanol and acetone.

7. A method for preparing the high-temperature resistant aluminum glitter powder according to any one of claims 1-6, characterized in that, The method includes the following steps: S1: Aluminum foil micro-roughening: After ultrasonic cleaning with an organic solvent, the aluminum foil is immersed in an alkaline solution, washed with water, and then immersed in a phosphoric acid / sodium chloride mixture, washed with water and dried to obtain pretreated aluminum foil. S2: Interface bridging pretreatment: KH-560 ethanol solution is evenly coated on both sides of the pretreated aluminum foil and dried. S3: Double-sided coating: A slurry containing cellulose acetate propionate, nanocellulose microfilaments, citric acid, pentaerythritol, sodium hypophosphite, high-temperature resistant pigments, and mixed solvents is uniformly coated onto both sides of the S2-treated aluminum foil. S4: Thermal crosslinking: The coated aluminum foil is sent into a high-temperature drying tunnel for crosslinking and curing. S5: Precision cutting and sieving: After cooling, the product is cut into the set shape to obtain the finished product.

8. The preparation method according to claim 7, characterized in that, In step S1, the aluminum foil thickness is 6-10 μm; the alkaline solution is a 0.8-1.2 mol / L sodium hydroxide solution, and the treatment time is 10-20 s; the phosphoric acid / sodium chloride mixture contains 0.1-0.3 mol / L phosphoric acid and 0.5-1.0 mol / L sodium chloride, and the treatment time is 25-35 s.

9. The preparation method according to claim 7, characterized in that, In step S2, the mass concentration of the KH-560 ethanol solution is 0.8-1.2%, the drying temperature is 75-85℃, and the drying time is 4-6 min; in step S4, the cross-linking curing temperature is 190-210℃, and the time is 4-6 min.

10. The application of the high-temperature resistant aluminum glitter powder according to any one of claims 1-6 in injection molded products, characterized in that, The processing temperature of the injection molded product is 250-300℃.

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