Ultrathin pearlescent material multicolor composite dispersion preparation process

Abstract

The invention relates to the technical field of material preparation, and discloses an ultrathin pearlescent material multicolor composite dispersion preparation process which comprises the following steps: S1, coating the surface of an artificial mica base material with a composite dispersion liquid formed by mixing sodium polyacrylate, modified nano silicon dioxide and hydroxypropyl methyl cellulose, dispersing the composite dispersion liquid in deionized water under the ultrasonic power of 250-350W and the frequency of 28kHz, and drying the composite dispersion liquid to obtain an ultrathin pearlescent material; the solid content of the composite dispersion liquid is 1.2-2.5 wt%, and the viscosity of the dispersion liquid is controlled to be 200-400 mPa.s. By constructing a sodium polyacrylate and modified nano silicon dioxide composite carrier system and combining a three-stage differential centrifugation method and a gradient dispersion process, the amination surface of the modified nano silicon dioxide enhances the interface bonding force with a polymer, a high-orientation multilayer structure is formed in the material, the light transmittance is improved, and the light transmittance is improved. The color shows more distinct layering sense and saturation degree, and the problem of optical performance degradation caused by uneven dispersion is solved.

Description

Technical Field

[0001] This invention relates to the field of materials preparation technology, specifically to a process for preparing multicolor composite dispersion of ultrathin pearlescent materials. Background Technology

[0002] As a novel optical functional material, ultrathin pearlescent materials are widely used in high-end packaging, smart displays, energy-saving materials, optical devices, anti-counterfeiting labels, and special printing. Their core value lies in generating dynamic optical effects through multi-layer color-developing structures, such as angle-changing color and iridescent gradients. Traditional preparation processes mainly rely on physical mixing and single-coating molding, which suffer from common problems such as mixed colors between layers and poor mechanical properties, severely restricting their application in emerging fields such as flexible electronics and micro-optical devices.

[0003] In existing technologies, traditional processes suffer from insufficient stability of the dispersion system and lack of interlayer control methods. Conventional dispersants are unable to maintain the stable suspension of nano-sized pearlescent particles, and the aggregation and sedimentation of particles cause uneven layer thickness, resulting in a decrease in optical performance during use. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a multi-color composite dispersion preparation process for ultrathin pearlescent materials, which solves the problem of uneven layer thickness caused by microparticle agglomeration and sedimentation, resulting in decreased optical performance during use.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a multi-color composite dispersion preparation process for ultrathin pearlescent materials, comprising the following steps:

[0006] S1. A composite dispersion consisting of sodium polyacrylate, modified nano silica, and hydroxypropyl methylcellulose in a mass ratio of (4.5-5.5):(2.2-2.8):1 is coated onto the surface of an artificial mica substrate with a particle size of 20-200 μm and a thickness of 80-120 nm. The mixture is then dispersed in deionized water under ultrasonic power of 250-350 W and frequency of 28 kHz to form a composite dispersion with a solid content of 1.2-2.5 wt%. The viscosity of the dispersion is controlled at 200-400 mPa·s.

[0007] S2. Place 2-3 kinds of pretreated artificial mica flakes with a particle size of 100-200μm into a citric acid-tartaric acid mixture with a pH of 4.8-5.2, and stir at a constant speed of 200-400rpm at 55-65℃ for 60-80min. After centrifugation, activated microparticles with nano-pits with a depth of 20-50nm on the surface are obtained.

[0008] S3. The color development sequence of activated microparticles of different color systems arranged in descending order of L value is added to the dispersion obtained in S1 in three batches. Each batch is subjected to pulsed ultrasonic treatment for 10-12 minutes at intervals. The ultrasonic parameters are adjusted to a duty cycle of 5 seconds working and 7 seconds intermittent, and the absolute value of the Zeta potential of the dispersion system is maintained at ≥40mV.

[0009] S4. Under vacuum conditions of -0.085 to -0.095 MPa, an alternating filtration deposition process is adopted, with a square wave pulse electric field of 2.0-2.5 kV / cm applied between layers at a frequency of 2.0-2.5 Hz. The polarity of the positive and negative electrodes is reversed every 4 deposition cycles, and the deposition rate is controlled at 0.05-0.08 μm / min.

[0010] S5. After each layer is deposited, the aluminum chelate is immersed in an ethanol solution at a 25° tilt angle. The chelate is a mixture of aluminum acetylacetonate and aluminum nitrate in a molar ratio of 1:2.5-1:3.5, with a solution concentration of 0.1-0.2 mol / L. The solution is allowed to stand for 8-10 minutes to allow it to permeate.

[0011] S6. Implement three-stage temperature control: the first stage is 50℃ / RH 65-70% for 20-30 minutes, the second stage is 80℃ / RH 45-50% for 15-25 minutes, and the third stage is 110℃ / RH ≤10% for 10-15 minutes. The heating rate of each stage is ≤3.0℃ / min.

[0012] S7. Perform 6 reciprocating calendering cycles in a twin-roll calender, with a roll temperature of 95-105℃, a linear pressure of 85-95 N / mm, and a roll speed ratio of 1:1.5-1:6. The thickness of the finished product after calendering is 0.6-0.8μm, with fluctuation ≤±0.1μm. Calcinate the calendered material in an argon atmosphere at 400-550℃ for 1-2 hours at a heating rate of 5-8℃ / min to obtain an inorganic composite pearlescent material.

[0013] Preferably, in step S2, the mixture contains citric acid and tartaric acid, prepared in a molar ratio of 3.0:1-3.5:1. The centrifugation separation adopts a three-stage differential centrifugation method, first centrifuging at 1200-1500 rpm for 3 min to remove agglomerates, and then centrifuging at 4500-5000 rpm for 5 min to collect target particles.

[0014] Preferably, in step S3, the construction of the color development sequence includes: measuring the reflectance curves of each color particle in the wavelength range of 350-780nm using a spectrophotometer, arranging the layers according to the standard that the reflectance difference between adjacent layers is ≥25%, and adding a titanium dioxide brightening layer with a refractive index of 2.3-2.4 to the first and last layers.

[0015] Preferably, the step between S4 and S5 includes a transition layer formation process, in which titanium dioxide particles with a particle size of 150-180 nm are deposited by aerosol to form a 0.2-0.4 μm buffer layer, with a deposition pressure of 0.2-0.3 MPa and a deposition rate of 0.05-0.08 μm / min.

[0016] Preferably, in step S6, after the third stage of drying, a rehumidification treatment is performed, in which the humidity is balanced for 2-3 hours in an environment of 25℃ / RH30-35% to stabilize the moisture content of the material at 0.8-1.2wt%.

[0017] Preferably, in step S7, the calender is equipped with a laser thickness gauge and an infrared temperature sensor to form a closed-loop control system. When a thickness deviation > 0.1 μm is detected, the roller spacing compensation is automatically adjusted to 1.2-1.5 times the deviation value.

[0018] Preferably, after step S7, a dynamic optical calibration process is included, in which a fiber optic spectrometer is used to detect the color difference of the film material online. When ΔE > 0.8, feedback adjustment is triggered to increase the roller temperature to 110-115℃ and increase the linear pressure to 90-100N / mm for compensatory calendering.

[0019] Preferably, the method for preparing the modified nano-silica includes: surface-treating silica particles with a particle size of 50-80 nm with γ-aminopropyltriethoxysilane in an argon atmosphere at a temperature of 110-120°C for 2-3 hours to obtain aminated modified nanoparticles.

[0020] Preferably, the rheological properties of the composite dispersion satisfy the following: at a shear rate of 1 s... -1 The viscosity is 450-500 mPa·s, and the shear rate is 100 s⁻¹. -1 The viscosity drops to 30-50 mPa·s, and the thixotropic index is 8.5-9.2.

[0021] Preferably, the drying time of each stage in step S6 satisfies a functional relationship:

[0022] t1 = 0.8 × (T1 × RH1) / A;

[0023] t2 = 1.2 × (T2 × RH2) / A;

[0024] t3 = 0.5 × (T3 × RH3) / A;

[0025] Where t is minutes, T is temperature (°C), RH is relative humidity (%), and A is membrane area (m²). 2) This invention provides a process for preparing multicolor composite dispersion of ultrathin pearlescent materials. It has the following beneficial effects:

[0026] 1. This invention constructs a composite carrier system of sodium polyacrylate and modified nano-silica, and combines a three-stage differential centrifugation method with a gradient dispersion process to achieve stable dispersion and orderly arrangement of multicolor pearlescent microparticles. The aminated surface of the modified nano-silica enhances the interfacial bonding force with the polymer, while the reflectivity difference control of the color sequence optimizes the light interference effect. A highly oriented multilayer structure is formed inside the material, which improves light transmittance and presents a more vivid sense of layering and saturation of colors, thus solving the problem of optical performance degradation caused by uneven dispersion.

[0027] 2. This invention significantly enhances the interfacial bonding between the pretreated pearlescent flakes and the dispersion through a microparticle pre-activation process and pulsed ultrasonic treatment. Combined with alternating vacuum filtration deposition and three-stage gradient drying, it effectively avoids the problems of microparticle agglomeration and drying cracking. In addition, the inclined penetration of the aluminum chelate ethanol solution strengthens the interlayer bonding strength, increasing the peel strength of the material by more than 40%, while reducing the total process time to 60% of the traditional method, significantly improving production efficiency.

[0028] 3. This invention achieves adaptive optimization of process parameters and product consistency control through a closed-loop control system and dynamic optical calibration, combined with a gradient drying mathematical model. It also provides real-time feedback from laser thickness gauges and infrared sensors, and controls the phase change process by quantifying the correlation between temperature, humidity and area, thereby stabilizing the moisture content at 0.8-1.2wt%, which reduces the product defect rate and improves production efficiency. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the process for preparing multicolor composite dispersion of ultrathin pearlescent materials according to the present invention. Detailed Implementation

[0030] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example:

[0032] Please see the appendix Figure 1 This invention provides a process for preparing multicolor composite dispersion of ultrathin pearlescent materials, including the following steps:

[0033] S1. A composite dispersion consisting of sodium polyacrylate, modified nano silica, and hydroxypropyl methylcellulose in a mass ratio of (4.5-5.5):(2.2-2.8):1 is coated onto the surface of an ultrathin artificial substrate. The substrate thickness is 80-120 nm. The dispersion is carried out in deionized water under ultrasonic power of 250-350 W and frequency of 28 kHz to form a composite dispersion with a solid content of 1.2-2.5 wt%. The viscosity of the dispersion is controlled at 200-400 mPa·s.

[0034] S2. Place 2-3 kinds of pretreated artificial mica flakes with a particle size of 100-200μm into a citric acid-tartaric acid mixture with a pH of 4.8-5.2, and stir at a constant speed of 200-400rpm at 55-65℃ for 60-80min. After centrifugation, activated microparticles with nano-pits with a depth of 20-50nm on the surface are obtained.

[0035] S3. The color development sequence of activated microparticles of different color systems arranged in descending order of L value is added to the dispersion obtained in S1 in three batches. Each batch is subjected to pulsed ultrasonic treatment for 10-12 minutes at intervals. The ultrasonic parameters are adjusted to a duty cycle of 5 seconds working and 7 seconds intermittent, and the absolute value of the Zeta potential of the dispersion system is maintained at ≥40mV.

[0036] S4. Under vacuum conditions of -0.085 to -0.095 MPa, an alternating filtration deposition process is adopted, with a square wave pulse electric field of 2.0-2.5 kV / cm applied between layers at a frequency of 2.0-2.5 Hz. The polarity of the positive and negative electrodes is reversed every 4 deposition cycles, and the deposition rate is controlled at 0.05-0.08 μm / min.

[0037] S5. After each layer is deposited, the aluminum chelate is immersed in an ethanol solution at a 25° tilt angle. The chelate is a mixture of aluminum acetylacetonate and aluminum nitrate in a molar ratio of 1:2.5-1:3.5, with a solution concentration of 0.1-0.2 mol / L. The solution is allowed to stand for 8-10 minutes to allow it to permeate.

[0038] S6. Implement three-stage temperature control: the first stage is 50℃ / RH 65-70% for 20-30 minutes, the second stage is 80℃ / RH 45-50% for 15-25 minutes, and the third stage is 110℃ / RH ≤10% for 10-15 minutes. The heating rate of each stage is ≤3.0℃ / min.

[0039] S7. Perform 6 reciprocating calendering cycles in a twin-roll calender, with a roll temperature of 95-105℃, a linear pressure of 85-95 N / mm, and a roll speed ratio of 1:1.5-1:6. The thickness of the finished product after calendering is 0.6-0.8μm, with fluctuation ≤±0.1μm. Calcinate the calendered material in an argon atmosphere at 400-550℃ for 1-2 hours at a heating rate of 5-8℃ / min to obtain an inorganic composite pearlescent material.

[0040] In step S2, the mixture contains citric acid and tartaric acid, prepared in a molar ratio of 3.0:1-3.5:1. Centrifugation is performed using a three-stage differential centrifugation method. First, the aggregates are removed by centrifugation at 1200-1500 rpm for 3 min, and then the target particles are collected by centrifugation at 4500-5000 rpm for 5 min.

[0041] In step S3, the construction of the color development sequence includes: measuring the reflectance curves of each color particle in the wavelength range of 350-780nm using a spectrophotometer, arranging the layers according to the standard that the reflectance difference between adjacent layers is ≥25%, and adding a titanium dioxide brightening layer with a refractive index of 2.3-2.4 to the first and last layers.

[0042] The step between S4 and S5 includes a transition layer formation process, in which titanium dioxide particles with a particle size of 150-180nm are deposited by aerosol to form a buffer layer of 0.2-0.4μm, with a deposition pressure of 0.2-0.3MPa and a deposition rate of 0.05-0.08μm / min.

[0043] In step S6, after the third stage of drying, a rehumidification treatment is carried out, and the humidity is balanced in an environment of 25℃ / RH30-35% for 2-3 hours to stabilize the material moisture content at 0.8-1.2wt%.

[0044] In step S7, the calender is equipped with a laser thickness gauge and an infrared temperature sensor to form a closed-loop control system. When a thickness deviation > 0.1 μm is detected, the roller spacing compensation is automatically adjusted to 1.2-1.5 times the deviation value.

[0045] Step S7 is followed by a dynamic optical calibration process, in which a fiber optic spectrometer is used to detect the color difference of the film material online. When ΔE > 0.8, feedback adjustment is triggered, which increases the roller temperature to 110-115℃ and increases the linear pressure to 90-100N / mm for compensatory calendering.

[0046] The preparation method of modified nano-silica includes: surface treatment of silica particles with a particle size of 50-80 nm with γ-aminopropyltriethoxysilane in an argon atmosphere, the treatment temperature is 110-120℃ and the treatment time is 2-3 hours, to obtain aminated modified nanoparticles.

[0047] The rheological properties of the composite dispersion satisfy the following: at a shear rate of 1 s⁻¹ -1 The viscosity is 450-500 mPa·s, and the shear rate is 100 s⁻¹. -1 The viscosity drops to 30-50 mPa·s, and the thixotropic index is 8.5-9.2.

[0048] The drying time of each stage in step S6 satisfies the following functional relationship:

[0049] t1 = 0.8 × (T1 × RH1) / A;

[0050] t2 = 1.2 × (T2 × RH2) / A;

[0051] t3 = 0.5 × (T3 × RH3) / A;

[0052] Where t is minutes, T is temperature (°C), RH is relative humidity (%), and A is membrane area (m²). 2 ).

[0053] The following is a description with reference to specific embodiments:

[0054] Example 1: Basic Process

[0055] S1. Coat the surface of an artificial mica substrate with a particle size of 150 μm and a thickness of 120 nm with 5.0 parts of sodium polyacrylate, 2.5 parts of modified nano-silica, and 1 part of hydroxypropyl methylcellulose. Disperse the mixture ultrasonically at 300 W / 28 kHz to form a dispersion with a solid content of 1.8 wt% and a viscosity of 480 mPa·s (1 s⁻¹). -1 ) to 45 mPa·s (100 s) -1 Thixotropic index 8.8;

[0056] S2. Using pretreated blue pearlescent flakes with a particle size of 150 μm, in a citric acid-tartaric acid (3.2:1) mixture at pH 5.0, the flakes were treated at 60℃ / 300 rpm for 70 min and then centrifuged three times from 1400 rpm to 4800 rpm to obtain activated microparticles with a pit depth of 30 nm.

[0057] S3. Arrange the layers according to a reflectivity difference of 26%, add in three batches, pulse ultrasound, work for 5 seconds, pause for 7 seconds three times, Zeta potential -44mV;

[0058] S4. Alternating filtration at -0.09MPa, applying a 2.2kV / cm square wave electric field (2.2Hz), with polarity reversal every 4 cycles, and a deposition rate of 0.06μm / min;

[0059] S5. A 0.3 μm TiO2 buffer layer was formed by aerosol deposition at a pressure of 0.25 MPa and a rate of 0.7 mm / min. Then, it was impregnated with a 0.15 mol / L aluminum chelate (1:3) ethanol solution for 9 min.

[0060] S6, three-stage drying, heating rate 2.8℃ / min, after the third stage, equilibrate for 2.5 hours in an environment of 25℃ / RH32%;

[0061] S7, 6-cycle reciprocating calendering (100℃ / 88N / mm / 1:1.6 speed ratio), thickness deviation automatically compensated to ±0.08μm, ΔE=0.7 after dynamic calibration.

[0062] Table 1. Basic Experimental Data

[0063] index Example 1 Compared with traditional craftsmanship Test Standards Total thickness 0.72μm±0.08μm 1.5μm±0.3μm GB / T6672-2001 interlayer bond strength 4.6 N / cm 2.4 N / cm ASTM D903 ΔE value (UV aging) 0.7-1.0 2.3-4.5 ISO105-B02 Difference in reflectance (%) 26 15 JISK7375 Bending durability No cracks after 500 bends at 180°. 50 instances of stratification GB / T2792

[0064] By combining the composite dispersion with a square wave pulsed electric field, an ultrathin thickness of 0.72 μm is achieved with a fluctuation of ≤ ±0.08 μm, breaking through the lower limit of traditional process thickness.

[0065] By utilizing a gold-silver sequence arrangement with a 23% difference in reflectivity and a TiO2 brightening layer, the ΔE value is reduced to as low as 0.7, and the color purity is improved by 74%.

[0066] Aluminum chelate interface treatment combined with closed-loop rolling control results in an interlayer bonding strength of 4.6 N / cm, with no delamination after 500 bends.

[0067] Example 2: High-performance process

[0068] A dispersion with a thixotropic index of 9.0 and a viscosity of 520 mPa·s was prepared on the surface of an artificial mica substrate with a particle size of 180 μm and a thickness of 100 nm using a mixing ratio of 5.5:2.2:1. -1 ) to 38 mPa·s (100 s) -1 );

[0069] Gold / red pearlescent flakes (180 μm) were treated in a pH 4.9 mixture (3.5:1) for 80 min, resulting in a pit depth of 45 nm.

[0070] A 27% reflectivity difference sequence, a Zeta potential of +47mV, and an extended pulse ultrasound working cycle to 5s;

[0071] An electric field of 2.5 kV / cm was applied to form a 0.4 μm TiO2 buffer layer through aerosol deposition at a deposition pressure of 0.28 MPa.

[0072] Using 0.18 mol / L chelating agent, after 10 min of penetration, the mixture was rehumidified for 3 hours in an environment of 25℃ / RH33%;

[0073] Triggered three-stage compensation rolling (105℃ / 95N / mm), surface roughness Ra=0.11μm.

[0074] Table 2, High-Performance Experimental Data Table

[0075]

[0076]

[0077] The light transmittance reaches 89-92% and the surface roughness Ra = 0.12μm is achieved by using a shear-thinned dispersion with a thixotropic index of 7.2 and an aerosol-deposited buffer layer.

[0078] Dynamic optical calibration reduces ΔE to only 0.9 after UV aging and lowers color shift tolerance by 73%.

[0079] The three-stage gradient drying process, combined with rehumidification treatment, achieves 10 days of no failure in anti-adhesion properties, increasing the yield rate to 97.8%.

[0080] Example 3: Rapid Production Process

[0081] A low-viscosity dispersion (230 mPa·s to 32 mPa·s) with a thixotropic index of 8.6 was prepared by mixing 4.8:2.8:1.

[0082] Two-color pearlescent flakes (particle size 120nm), rapidly processed at pH 5.1 for 65min, with a pit depth of 25nm;

[0083] 2.0 kV / cm electric field, 2.5 Hz high-frequency reversal, deposition rate 0.08 μm / min;

[0084] Calculated using the function: t1 = 28min(0.8 × (50 × 68) / 0.5m) 2 ), t2=24min(1.2×(80×48) / 0.5m 2 ), t3=9min(0.5×(110×8) / 0.5m 2 );

[0085] With a roll speed ratio of 1:1.6, the thickness after 6 calendering cycles is 0.65μm, and ΔE = 0.8.

[0086] Table 3, High-performance experimental data table

[0087] index Example 3 Compared with traditional craftsmanship Test Standards Dynamic color shift angle 15°-60° hue change 25°-50° hue blur Spectrophotometer Temperature resistance No stratification between -20℃ and 120℃ Delamination cracking occurs at temperatures ranging from -10℃ to 80℃. High and low temperature test chamber Antistatic properties <![CDATA[Surface resistance 1.2×10 9 Ω]]> <![CDATA[Surface resistance 5.8×10 12 Ω]]> ASTM D257 Peel strength Longitudinal 4.3 N / cm 1.8 N / cm GB / T2790 Haze 2.8％ 6.5％ ASTMD1003

[0088] By using a TiO2 transition layer with a particle size of 120 nm and aminated modified nano-SiO2, a dynamic color shift of 15° to 60° is achieved, expanding the hue change range by 80%.

[0089] Gradient drying combined with RH 33% balanced rehumidification, temperature range of -20 to 120℃, and fog level as low as 2.8% meet the needs of extreme environment applications.

[0090] With optimized antistatic properties and peel strength, it can be directly used in high-speed composite production lines.

[0091] Table 4, Comparative Analysis Table

[0092] index Example 1 Example 2 Example 3 Traditional crafts Minimum thickness 0.42μm 0.38μm 0.45μm 1.5μm interlayer bond strength 4.1 N / cm 3.9 N / cm 4.3 N / cm 2.2 N / cm ΔE stability 0.7 0.5 0.8 ≤0.8 Production yield 98.5％ 97.8％ 98.2％ 82.3％ Energy efficiency <![CDATA[1.2kW·h / m 2 ]]> <![CDATA[1.3kW·h / m 2 ]]> <![CDATA[1.1kW·h / m 2 ]]> <![CDATA[2.8kW·h / m 2 ]]> Suitable production scenarios conventional decorative materials High-end optical devices Fast-moving consumer goods packaging -

[0093] Breakthrough in ultra-thin design: Thickness reduced by more than 40%;

[0094] Performance improvements: interlayer bonding strength increased by 86%, color stability ΔE decreased by 65%;

[0095] Energy saving and efficiency improvement: Unit energy consumption is reduced by 57%, and yield rate is improved by 16 percentage points.

[0096] Based on the prepared inorganic composite pearlescent material, the addition of ultraviolet absorbers can be used in automotive coatings; the addition of wear-resistant coatings can be used in building decoration; the addition of antistatic agents can be used in packaging materials; and the combination with silver nanowires can be used in flexible electronics.

[0097] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A process for preparing multicolor composite dispersion of ultrathin pearlescent materials, characterized in that, Includes the following steps: S1. A composite dispersion consisting of sodium polyacrylate, modified nano silica, and hydroxypropyl methylcellulose in a mass ratio of (4.5-5.5):(2.2-2.8):1 is coated onto the surface of an artificial mica substrate with a particle size of 20-200 μm and a thickness of 80-120 nm. The mixture is then dispersed in deionized water under ultrasonic power of 250-350 W and frequency of 28 kHz to form a composite dispersion with a solid content of 1.2-2.5 wt%. The viscosity of the dispersion is controlled at 200-400 mPa·s. S2. Place 2-3 kinds of pretreated artificial mica flakes with a particle size of 100-200μm into a citric acid-tartaric acid mixture with a pH of 4.8-5.2, and stir at a constant speed of 200-400rpm at 55-65℃ for 60-80min. After centrifugation, activated microparticles with nano-pits with a depth of 20-50nm on the surface are obtained. S3. The color development sequence of activated microparticles of different color systems arranged in descending order of L value is added to the dispersion obtained in S1 in three batches. Each batch is subjected to pulsed ultrasonic treatment for 10-12 minutes at intervals. The ultrasonic parameters are adjusted to a duty cycle of 5 seconds working and 7 seconds intermittent, and the absolute value of the Zeta potential of the dispersion system is maintained at ≥40mV. S4. Under vacuum conditions of -0.085 to -0.095 MPa, an alternating filtration deposition process is adopted, with a square wave pulse electric field of 2.0-2.5 kV / cm applied between layers at a frequency of 2.0-2.5 Hz. The polarity of the positive and negative electrodes is reversed every 4 deposition cycles, and the deposition rate is controlled at 0.05-0.08 μm / min. S5. After each layer is deposited, the aluminum chelate is immersed in an ethanol solution at a 25° tilt angle. The chelate is a mixture of aluminum acetylacetonate and aluminum nitrate in a molar ratio of 1:2.5-1:3.5, with a solution concentration of 0.1-0.2 mol / L. The solution is allowed to stand for 8-10 minutes to allow it to permeate. S6. Implement three-stage temperature control: the first stage is 50℃ / RH 65-70% for 20-30 minutes, the second stage is 80℃ / RH 45-50% for 15-25 minutes, and the third stage is 110℃ / RH ≤10% for 10-15 minutes. The heating rate of each stage is ≤3.0℃ / min. S7. Perform 6 reciprocating calendering cycles in a twin-roll calender, with a roll temperature of 95-105℃, a linear pressure of 85-95 N / mm, and a roll speed ratio of 1:1.5-1:

6. The thickness of the finished product after calendering is 0.6-0.8μm, with fluctuation ≤±0.1μm. Calcinate the calendered material in an argon atmosphere at 400-550℃ for 1-2 hours at a heating rate of 5-8℃ / min to obtain an inorganic composite pearlescent material.

2. The preparation process of multicolor composite dispersion of ultrathin pearlescent materials according to claim 1, characterized in that: In step S2, the mixture contains citric acid and tartaric acid, prepared in a molar ratio of 3.0:1-3.5:

1. Centrifugation is performed using a three-stage differential centrifugation method, first centrifuging at 1200-1500 rpm for 3 min to remove agglomerates, and then centrifuging at 4500-5000 rpm for 5 min to collect target particles.

3. The preparation process of multicolor composite dispersion of ultrathin pearlescent materials according to claim 1, characterized in that: In step S3, the construction of the color development sequence includes: measuring the reflectance curves of each color particle in the wavelength range of 350-780nm using a spectrophotometer, arranging the layers according to the standard that the reflectance difference between adjacent layers is ≥25%, and adding a titanium dioxide brightening layer with a refractive index of 2.3-2.4 to the first and last layers.

4. The preparation process of multicolor composite dispersion of ultrathin pearlescent materials according to claim 1, characterized in that: The step between S4 and S5 includes a transition layer formation process, in which titanium dioxide particles with a particle size of 150-180nm are deposited by aerosol to form a 0.2-0.4μm buffer layer, with a deposition pressure of 0.2-0.3MPa and a deposition rate of 0.05-0.08μm / min.

5. The preparation process of multicolor composite dispersion of ultrathin pearlescent materials according to claim 1, characterized in that: In step S6, after the third stage of drying, a rehumidification treatment is carried out, in which the humidity is balanced for 2-3 hours in an environment of 25℃ / RH30-35% to stabilize the moisture content of the material at 0.8-1.2wt%.

6. The preparation process of multicolor composite dispersion of ultrathin pearlescent materials according to claim 1, characterized in that: In step S7, the calender is equipped with a laser thickness gauge and an infrared temperature sensor to form a closed-loop control system. When a thickness deviation > 0.1 μm is detected, the roller spacing compensation is automatically adjusted to 1.2-1.5 times the deviation value.

7. The preparation process of multicolor composite dispersion of ultrathin pearlescent materials according to claim 1, characterized in that: Step S7 is followed by a dynamic optical calibration process, in which a fiber optic spectrometer is used to detect the color difference of the film material online. When ΔE > 0.8, feedback adjustment is triggered to increase the roller temperature to 110-115℃ and increase the linear pressure to 90-100N / mm for compensatory calendering.

8. The preparation process of multicolor composite dispersion of ultrathin pearlescent materials according to claim 1, characterized in that: The method for preparing the modified nano-silica includes: surface-treating silica particles with a particle size of 50-80 nm with γ-aminopropyltriethoxysilane in an argon atmosphere at a temperature of 110-120°C for 2-3 hours to obtain aminated modified nanoparticles.

9. The multicolor composite dispersion preparation process for ultrathin pearlescent materials according to claim 1, characterized in that: The rheological properties of the composite dispersion satisfy the following: at a shear rate of 1s... -1 The viscosity is 450-500 mPa·s, and the shear rate is 100 s⁻¹. -1 The viscosity drops to 30-50 mPa·s, and the thixotropic index is 8.5-9.

2.

10. The preparation process of multicolor composite dispersion of ultrathin pearlescent materials according to claim 1, characterized in that: The drying time in each stage of step S6 satisfies a functional relationship: t1 = 0.8 × (T1 × RH1) / A; t2 = 1.2 × (T2 × RH2) / A; t3 = 0.5 × (T3 × RH3) / A; Where t is minutes, T is temperature (°C), RH is relative humidity (%), and A is membrane area (m²). 2 ).

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