A method for preparing a high whiteness resin

Abstract

The present application relates to the technical field of resin, and relates to a preparation method of high-whiteness resin, respectively preparing mesoporous SiO2@Eu 3+ The two whitening agents are mixed in a weight ratio of 1:1 to 1:4, surface modification is carried out, and then the whitening agents are melt-blended with a resin matrix; an intelligent control system is used to real-time regulate process parameters, so that the whiteness is greater than or equal to 96, and the thermal decomposition temperature is greater than or equal to 380 DEG C; the present application realizes the synergistic effect of the mesoporous SiO2@Eu 3+ The whitening agent and the TiO2 photonic crystal whitening agent synergistically act, and surface modification is carried out by using a silane coupling agent, so that the whitening agent is uniformly and stably dispersed in the resin matrix, the whiteness of the resin product is greater than or equal to 96, the risk of yellowing is reduced, and the visual appearance quality of the resin product is greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of resin, more particularly, it relates to a preparation method of high-whiteness resin. BACKGROUND

[0002] In the preparation process of high molecular materials such as plastics, fibers or films, the materials usually need to be whitened or brightened to improve the appearance quality and visual appeal. The existing whitening technology often uses inorganic pigments (such as ordinary TiO2, calcium carbonate, etc.) or fluorescent whitening agents (such as diphenyl type, benzoxazole type fluorescent whitening agents) to improve the whiteness and brightness of the product surface. However, the traditional whitening agent has the following disadvantages in the use process:

[0003] Although the use of inorganic pigments such as TiO2 alone can increase the opacity and whiteness of the material to a certain extent, it is difficult to achieve ultra-high whiteness (CIE Whiteness≥96) which requires higher and higher visual effect.

[0004] The traditional fluorescent whitening agent is prone to decomposition or failure during thermal processing, which makes it difficult to maintain the whitening effect for a long time.

[0005] Many whitening systems are prone to decomposition or yellowing during high-temperature melt blending or subsequent processing, affecting the appearance stability and service life of the product. For resin products that need to be used for a long time or at high temperature, if the heat resistance of the whitening agent is not good, it is difficult to ensure that the overall thermal decomposition temperature of the material is ≥380℃, which may cause potential safety and quality problems.

[0006] Therefore, how to select a whitening material with high whiteness and high thermal stability during resin preparation, and through reliable surface modification and processing technology, to realize the uniform dispersion, stable combination and controllable addition of the whitening agent in the matrix, and to overcome the problems of insufficient whiteness, low thermal decomposition temperature, poor interfacial compatibility and lack of online control of traditional whitening system, has become a key technical problem to be solved in the field. Especially in the application scenarios with higher requirements for material optical performance and thermal stability (such as high-end electronic materials, automotive interior parts, outdoor weather-resistant products, etc.), it is necessary to further improve the whiteness of the product, reduce the risk of yellowing, and ensure its reliability and processability at high temperature. SUMMARY

[0007] Therefore, the purpose of the present application is to provide a preparation method of high-whiteness resin, which can meet the requirements of ultra-high whiteness (CIE Whiteness≥96) and higher thermal decomposition temperature (≥380℃) at the same time.

[0008] To achieve the above purpose, the present application provides the following technical solutions:

[0009] A preparation method of high-whiteness resin comprises the following steps:

[0010] S1, respectively preparing mesoporous SiO2@Eu 3+ Whitening agent and TiO2 photonic crystal whitening agent,

[0011] S2, mixing two kinds of whitening agents in a weight ratio of 1:1-1:4, and melt blending with the resin matrix after surface modification;

[0012] S3, using an intelligent control system to real-time control process parameters, to ensure that the whiteness is greater than or equal to 96, and the thermal decomposition temperature is greater than or equal to 380 DEG C.

[0013] The application further provides that: the mesoporous SiO2@Eu 3+ The preparation process of the whitening agent is as follows:

[0014] The cetyltrimethylammonium bromide is dissolved in ethanol, and mixed in a volume ratio of 4:1, and stirred at 40 DEG C for 30 minutes;

[0015] The ethyl silicate is added dropwise, and reacted at 40 DEG C for 6 hours, and after centrifugal washing, calcined at 560-650 DEG C for 6 hours, to obtain mesoporous SiO2 with an average pore size of 2-10 nm, and a specific surface area greater than or equal to 300 m² / g;

[0016] The obtained mesoporous SiO2 is immersed in a europium nitrate solution with a concentration of 0.1-0.5 mol / L and a pH value controlled at 5.5-7.5, and ultrasonic treated for 1-3 hours, so that Eu 3+ The doping amount is 1-5% of the mass of the mesoporous SiO2;

[0017] After vacuum drying at 60 DEG C, annealing is performed in a manner of keeping at 200 DEG C for 1 hour, and then increasing the temperature to 260-350 DEG C and keeping for 2 hours, to obtain Eu 3+ The mesoporous SiO2@Eu 3+ Whitening agent.

[0018] The application further provides that: in the step S1, the preparation process of the TiO2 photonic crystal whitening agent comprises:

[0019] The tetrabutyl titanate is added dropwise into the ethanol mixture, and hydrolyzed at 80 DEG C for 12 hours, and centrifuged to obtain TiO2 nanospheres with an average particle size of 180-220 nm and a particle size dispersion coefficient not more than 0.1;

[0020] The TiO2 nanospheres are dispersed in a 5wt% dispersion liquid, and vertically deposited at 45 DEG C for 48 hours, to form a photonic crystal film with a thickness of 5-10 microns;

[0021] The TiO2 photonic crystal whitening agent is obtained by growing a 5nm-thick SiO2 coating layer through atomic layer deposition (ALD) at 150℃ for 50 cycles of SiCl4 / H2O.

[0022] The application further provides that in the step S2, the silane coupling agent is added in an amount of 3-8% by weight of the mixed whitening agent, and the following process is used:

[0023] The mixed whitening agent and the silane coupling agent are added into ethanol in a weight ratio of 3-8%, and pre-dispersed at 40℃ for 1-2 hours under ultrasonic power of 200-300W and frequency of 40kHz;

[0024] After constant stirring at 60℃ for 3 hours, the modified material is obtained by vacuum drying at 80℃ for 6 hours;

[0025] Finally, the material is melt blended with a resin matrix at 180-220℃ and screw rotation speed of 150-250rpm.

[0026] The application further provides that the surface modification comprises:

[0027] The mixed whitening agent and the silane coupling agent are added into ethanol in a weight ratio of 3-8%, and pre-dispersed at 40℃ for 1-2 hours, stirred at 60℃ for 3 hours, and dried at 80℃ for 6 hours to obtain a material,

[0028] The material is melt blended by using a double-screw extruder with stepwise temperature control, and the process parameters are as follows:

[0029] Feeding section: the resin matrix is added into the double-screw extruder, the temperature is controlled at 170-180℃, the residence time is 2-3 minutes, and the screw rotation speed is 50-100rpm.

[0030] Melt section 1: the material is added into the double-screw extruder, the temperature is controlled at 190-200℃, the residence time is 2-3 minutes, and the screw rotation speed is 150-200rpm.

[0031] Melt section 2: the temperature is controlled at 200-210℃, the residence time is 3-5 minutes, and the screw rotation speed is 200-250rpm.

[0032] Homogenization section: the temperature is controlled at 200-210℃, the residence time is 1-2 minutes, vacuum devolatilization is set, and the screw rotation speed is 150-180rpm.

[0033] Die section: the temperature is controlled at 180-190℃, the residence time is 1-3 minutes, and the screw rotation speed is 80-120rpm.

[0034] In the above melt blending process, the screw torque and extrusion pressure are monitored in real time, and appropriate adjustments are made through the intelligent control system to avoid material overheating degradation and ensure uniform dispersion of the whitening agent,

[0035] The application further provides that the intelligent control system comprises:

[0036] A temperature sensor and a PID controller are used to maintain temperature fluctuations of less than or equal to ±1℃;

[0037] An online colorimeter is used to detect the whiteness and yellowing index of the extruded strip at a sampling frequency of 1Hz, and a feedback algorithm is used to dynamically adjust the mixing ratio of the whitening agent or the extruder process parameters;

[0038] A machine learning model is used to train and predict based on historical batch data and in combination with screw torque, extrusion pressure, vacuum degree, etc., to optimize the mixing ratio of the whitening agent and the processing parameters in real time.

[0039] The application further provides that the machine learning model is a neural network, the input parameters at least include resin type, whitening agent ratio, processing temperature, screw torque, vacuum degree and extrusion pressure, the output predicts whiteness and yellowing index, and the training weight can be continuously updated according to the collected data.

[0040] The application further provides that the mesoporous SiO2@Eu 3+ Before mixing the whitening agent and the TiO2 photonic crystal whitening agent, the following steps are further included:

[0041] The mesoporous SiO2@Eu 3+ The whitening agent and the TiO2 photonic crystal whitening agent are pre-dispersed, dispersed in anhydrous ethanol or other low-polarity solvents, and the agglomerates are dispersed by ultrasonic oscillation to ensure monodispersity.

[0042] The pH value of the dispersion liquid is adjusted to a neutral range (6-7), and stirring is performed at 50-60℃ for 0.5-1 hours to inhibit secondary agglomeration.

[0043] The well-dispersed powdery whitening agent is obtained by filtration or centrifugation, and the two whitening agents are mixed according to the above-mentioned ratio.

[0044] The application further provides that the resin matrix further includes a pre-drying step before being added to the twin-screw extruder, i.e., the resin matrix is subjected to a 2-4 hour baking treatment at 80-120℃ to reduce the moisture content to below 0.1%.

[0045] The application further provides that it comprises: resin matrix: 85-95wt%;

[0046] Mixed whitening agent: 3-10wt%;

[0047] Optionally, 0.1-2wt% of antioxidant is added.

[0048] Compared with the deficiencies of the prior art, the beneficial effects of the present application are:

[0049] By using mesoporous SiO2@Eu 3+ The whitening agent and the TiO2 photonic crystal whitening agent synergize, and the surface is modified by using a silane coupling agent, so that the whitening agent obtains more uniform and stable dispersion in the resin matrix, can realize CIE Whiteness ≥ 96 of super-high whiteness, and at the same time reduces the risk of yellowing, and greatly improves the visual appearance quality of the resin product. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 The process flowchart of the present application. DETAILED DESCRIPTION

[0051] The following will give a detailed embodiment (or specific implementation) to further illustrate the feasibility and superiority of the high-whiteness resin preparation method according to the present application, combined with the specific process route and formula of the present application. It should be understood that the following embodiment is only used to illustrate the technical scheme of the present application, and is not a limitation of the present application; various modifications, changes or replacements can be made by those skilled in the art without departing from the essential spirit of the present application, and all should be considered to fall within the protection scope of the present application.

[0052] REFERENCE Figure 1 The present application further illustrates the preparation method of a high-whiteness resin.

[0053] Raw material preparation: resin matrix - polypropylene (PP, melt index 12g / 10min, grade certain industrial grade) is selected as an exemplary matrix resin. Before the PP is put into the twin-screw extruder, it is first placed in a 100℃ condition for 3 hours of material drying, so as to reduce the moisture content to about 0.1% or less, and reduce the risk of defects and yellowing caused by water vaporization during melt blending.

[0054] Explanation: The present application is also applicable to other thermoplastic resins (such as PET, PA, PC, etc.), and only the temperature, screw speed and other parameters need to be adjusted appropriately during subsequent melt blending.

[0055] Whitening agent raw materials: cetyltrimethylammonium bromide (CTAB); ethyl silicate (TEOS), analytical pure; europium nitrate (Eu(NO3)3), analytical pure; tetrabutyl titanate (TBOT), analytical pure; anhydrous ethanol; silane coupling agent (γ-aminopropyl triethoxysilane, etc.).

[0056] Other additives: antioxidant (optional), such as hindered phenol or phosphite, the amount of addition can be selected in the range of 0.1 ~ 2wt% according to the performance requirements; light stabilizer (optional), such as hindered amine (HALS) or benzotriazole.

[0057] The necessary instruments include: ultrasonic instrument (200 ~ 300W, 40kHz), high speed stirrer, vacuum drying oven, double screw extruder with temperature control (with vacuum devolatilization port and online detection device) and so on.

[0058] Mesoporous SiO2@Eu 3+ Preparation of whitening agent: hexadecyl trimethyl ammonium bromide (CTAB) is dissolved in anhydrous ethanol, and mixed according to the volume ratio of 4:1 (ethanol: aqueous solution), stirred at 40℃ for 30 minutes;

[0059] Slowly add ethyl silicate (TEOS), continue to react at 40℃ for 6 hours to generate SiO2 precursor;

[0060] After centrifugal washing, the product is calcined at 560 ~ 650℃ for 6 hours to remove the template agent, and mesoporous SiO2 powder with an average pore size of 2 ~ 10nm and a specific surface area of ≥300m² / g is obtained.

[0061] Eu 3+ Doping modification: prepare a 0.3mol / L europium nitrate solution with a pH value of about 6, and the Eu 3+ The doping amount is 3% of the mass of mesoporous SiO2 as the target;

[0062] Immerse the mesoporous SiO2 in the europium nitrate solution, and treat it under the ultrasonic instrument (power 250W, 40kHz) for 2 hours to ensure that the Eu 3+ Uniformly penetrates into the mesoporous structure; then vacuum drying at 60℃ to remove excess solution;

[0063] After drying the solid, preheat at 200℃ for 1 hour, then heat to 320℃ for 2 hours for annealing, to obtain mesoporous SiO2@Eu 3+ Uniformly doped and with fluorescent whitening effect 3+ Whitening agent.

[0064] Preparation of TiO2 photonic crystal whitening agent: drop tetrabutyl titanate (TBOT) into ethanol-water mixture, control the temperature at 80℃, and hydrolyze for 12 hours;

[0065] Centrifugal separation to obtain TiO2 nanospheres with an average particle size of about 200nm and a particle size dispersion coefficient not more than 0.1; the product is vacuum dried at 60℃ for 6 hours for standby.

[0066] Photonic crystal thin film construction:

[0067] The TiO2nanospheres are dispersed in a 5wt% dispersion liquid (volume ratio of anhydrous ethanol / water 4:1) by ultrasonic dispersion and stirring to avoid secondary agglomeration;

[0068] The TiO2nanospheres are self-assembled on the substrate to form a photonic crystal film with a thickness of 5-10μm by vertical deposition at 45°C for 48 hours;

[0069] The photonic crystal film is dried, peeled off or crushed into a micron-level sheet structure for standby use.

[0070] ALD coating: an atomic layer deposition (ALD) is used to grow a SiO2layer with a thickness of about 5nm by 50 times of SiCl4 / H2O cycles at 150°C; the coating layer can make the TiO2photonic crystal whitening agent maintain more stable optical and chemical properties during high-temperature processing.

[0071] Whitening agent pre-dispersion and mixing: the mesoporous SiO2@Eu 3+ The whitening agent and the TiO2photonic crystal whitening agent are subjected to ultrasonic oscillation for 0.5-1 hour at a low concentration (such as 2-3wt%) of anhydrous ethanol solution, and stirring at 50-60°C for 0.5-1 hour to reduce agglomeration; the pH value of the dispersion liquid is adjusted to 6-7, and the well-dispersed powder is collected by filtration or centrifugation again.

[0072] Mixed whitening agent: the mesoporous SiO2@Eu 3+ The whitening agent and the TiO2photonic crystal whitening agent are uniformly mixed; or the ratio of the two whitening agents is flexibly adjusted in the range of 1:1-1:4 according to the whiteness requirement of the product.

[0073] Surface modification and preparation of mixed mass: 100g of the mixed whitening agent powder is added to an anhydrous ethanol solution containing 3-8wt% (relative to the total mass of the whitening agent) of a silane coupling agent;

[0074] The particles are treated by ultrasonic power of 250W and frequency of 40kHz for 1 hour at 40°C to ensure that the surface of the particles is fully contacted with the coupling agent; then the coupling agent is hydrolyzed and condensed on the surface of the particles by constant stirring at 60°C for 3 hours; finally, the hydrophobic modified whitening agent mass is obtained by vacuum drying at 80°C for 6 hours.

[0075] Preliminary compounding of mixed whitening agent and resin matrix: the resin matrix 90wt%, the whitening agent 7wt%, and other additives (such as antioxidant 1wt%) are premixed in an appropriate amount; if higher weather resistance is required, 0.5-1wt% of a light stabilizer can be added, and the mixture is uniformly mixed for standby use.

[0076] Stepwise temperature control melt blending process: the above ingredients are subjected to stepwise temperature control melt blending through a twin-screw extruder, and specific parameters are shown as follows (combined with online intelligent control system monitoring):

[0077] Feeding section:

[0078] Temperature control: 170-180℃

[0079] Residence time: 2-3 minutes

[0080] Screw rotation speed: 50-100 rpm

[0081] Operation: The dried PP resin matrix is continuously fed into the feeding port of the extruder.

[0082] Melt section 1:

[0083] Temperature control: 190-200℃

[0084] Residence time: 2-3 minutes

[0085] Screw rotation speed: 150-200 rpm

[0086] Operation: The modified whitening agent prepared in the foregoing is added in this section; high shear action is beneficial to further dispersion.

[0087] Melt section 2:

[0088] Temperature control: 200-210℃

[0089] Residence time: 3-5 minutes

[0090] Screw rotation speed: 200-250 rpm

[0091] Operation: The material is fully melted, mixed, plasticized, and formed into a uniform melt.

[0092] Homogenization section:

[0093] Temperature control: 200-210℃

[0094] Residence time: 1-2 minutes

[0095] Vacuum devolatilization: -0.07 to -0.09 MPa

[0096] Screw rotation speed: 150-180 rpm

[0097] Operation: Eliminate possible residual low molecular weight substances, moisture or solvents to prevent degradation and bubble formation.

[0098] Die section:

[0099] Temperature control: 180-190℃

[0100] Dwell time: 1-3 minutes

[0101] Screw rotation speed: 80-120 rpm

[0102] Operation: The extrusion melt is shaped through the die to obtain high-whiteness resin strips or particles of predetermined shape.

[0103] Intelligent control system for online monitoring and dynamic control: An online colorimeter is installed on the die section or the cooling conveyor belt after extrusion, with a sampling frequency of 1 Hz, to detect the whiteness and yellowing index of the resin strips in real time.

[0104] When the whiteness deviates, the amount of whitening agent added (if side feeding or another feeding port is used) or the temperature of the melting section is slightly changed to maintain the target whiteness ≥ 96 through feedback algorithm.

[0105] PID temperature control and machine learning optimization: The temperature sensors of each extrusion section work with the PID controller to maintain temperature fluctuations ≤ ± 1℃; record the key process parameters such as screw torque, vacuum degree, and extrusion pressure, input them into the pre-trained neural network model, and combine historical production batch data for real-time prediction and adaptive adjustment to prevent thermal degradation and whiteness decline due to excessive shear or high temperature.

[0106] Example 1:

[0107] Raw materials and pretreatment:

[0108] Resin matrix pre-drying: Select polypropylene (PP) with a melt index of 12 g / 10 min, and dry at 80℃ for 2 hours to reduce the moisture content to about 0.1% or less.

[0109] Eu(NO3)3 solution: Prepare a concentration of 0.1 mol / L, pH = 5.5;

[0110] Eu 3+ Doping amount: 1% of the mass of mesoporous SiO2;

[0111] Mesoporous SiO2 annealing: preheat at 200℃ for 1 hour, then heat to 260℃ for 2 hours;

[0112] TiO2 nanospheres: target particle size of 180-220 nm, with 180 nm as the target particle size;

[0113] Photonic crystal film thickness: 5 μm;

[0114] ALD coating: SiO2 thickness of 5 nm;

[0115] Mixed whitening agent ratio: mesoporous SiO2@Eu 3+ : TiO2 photonic crystal = 1:1;

[0116] Silane coupling agent addition amount: 3% relative to the total mass of the whitening agent.

[0117] Key points of whitening agent preparation and modification:

[0118] Mesoporous SiO2@Eu 3+ Obtained at a lower doping concentration and relatively low temperature annealing conditions;

[0119] The TiO2 nanosphere hydrolysis time, vertical deposition time, and ALD cycle all use the lower limit of the range.

[0120] Surface modification: ultrasonic at 40°C for 1 hour, stirring at 60°C for 3 hours, and vacuum drying at 80°C for 6 hours.

[0121] Batching and melt blending

[0122] PP: 90wt%, mixed whitening agent: 7wt%, antioxidant: 1wt%, other trace additives: 2wt% (if needed), pre-mixed into a twin-screw extruder;

[0123] Segmented temperature control (mainly taking the lower range of temperature and rotational speed of each segment):

[0124] Feeding section: 170°C, 2 minutes, screw rotational speed 50rpm

[0125] Melt section 1: 190°C, 2 minutes, screw rotational speed 150rpm

[0126] Melt section 2: 200°C, 3 minutes, screw rotational speed 200rpm

[0127] Homogenization section: 200°C, 1 minute, vacuum degree -0.07MPa, screw rotational speed 150rpm

[0128] Die section: 180°C, 1 minute, screw rotational speed 80rpm

[0129] Online detection: set online colorimeter (sampling frequency 1Hz), PID temperature control error ≤±1°C.

[0130] Example Two:

[0131] Raw materials and pretreatment

[0132] Fat matrix pre-drying: 100°C, 3 hours;

[0133] Eu nitrate solution: 0.3mol / L, pH=6.5;

[0134] Eu 3+ Doping amount: 3%;

[0135] Mesoporous SiO2 annealing: 200℃ preheating for 1 hour, then heating to 320℃ for 2 hours;

[0136] TiO2 nanospheres: target particle size about 200nm;

[0137] Photonic crystal film thickness: about 7μm;

[0138] ALD coating: 5nm;

[0139] Mixed whitening agent ratio: 1:2;

[0140] Silane coupling agent addition: 5%.

[0141] Whitening agent preparation and modification points:

[0142] Eu 3+ Solution concentration and doping amount median, ensure high fluorescent whitening efficiency;

[0143] TiO2 hydrolysis, deposition time and ALD times are carried out according to the conventional standard;

[0144] Modification process: ultrasonic at 40℃ for 1 hour, stirring at 60℃ for 3 hours, vacuum drying at 80℃ for 6 hours.

[0145] Batching and melt blending

[0146] PP: 90wt%, mixed whitening agent: 7wt%, antioxidant: 1wt%;

[0147] Segmented temperature control (select the middle value):

[0148] Feeding section: 175℃, 2.5 minutes, screw speed 75rpm

[0149] Melt section 1: 195℃, 2.5 minutes, screw speed 175rpm

[0150] Melt section 2: 205℃, 4 minutes, screw speed 225rpm

[0151] Homogenization section: 205℃, 1.5 minutes, vacuum degree-0.08MPa, screw speed 160rpm

[0152] Die section: 185℃, 2 minutes, screw speed 100rpm

[0153] Online monitoring: automatic collection of extrusion pressure, screw torque and whiteness, after real-time analysis by neural network model, if deviating from the target whiteness, the feeding amount or melt section temperature can be adjusted slightly.

[0154] Example three:

[0155] Raw materials and pretreatment

[0156] Resin matrix pre-drying: 120℃, 4 hours;

[0157] Eu nitrate solution: 0.5 mol / L, pH = 7.5;

[0158] Eu 3+ Doping amount: 5%;

[0159] Mesoporous SiO2 annealing: preheating at 200℃ for 1 hour, then heating to 350℃ for 2 hours;

[0160] TiO2 nanospheres: upper limit value 220nm;

[0161] Photonic crystal film thickness: 10μm;

[0162] ALD coating: 5nm;

[0163] Mixed whitening agent ratio: 1:4;

[0164] Silane coupling agent addition amount: 8%.

[0165] Whitening agent preparation and modification points

[0166] Eu 3+ Both concentration and doping amount take larger values to obtain stronger fluorescence properties;

[0167] TiO2 self-assembly and ALD process are carried out under high-end conditions to ensure the best photonic crystal structure;

[0168] Modification process: upper limit of ultrasonic power and time (250W, 1 hour), followed by drying at 80℃ for 6 hours.

[0169] Batching and melt blending

[0170] PP: 90wt%, mixed whitening agent: 7wt%, antioxidant: 1wt%;

[0171] Segmented temperature control (take high-end parameters):

[0172] Feeding section: 180℃, 3 minutes, screw speed 100rpm

[0173] Melt section 1: 200℃, 3 minutes, screw speed 200rpm

[0174] Melt section 2: 210℃, 5 minutes, screw speed 250rpm

[0175] Homogenization section: 210℃, 2 minutes, vacuum degree -0.09MPa, screw speed 180rpm

[0176] Die section: 190℃, 3 minutes, screw speed 120rpm

[0177] Online monitoring: Machine learning model integrates more historical data to dynamically predict extrusion pressure, torque, and whiteness (CIE Whiteness), and adjust the process in time to ensure the final high whiteness level.

[0178] Detection results and comparison

[0179] The following table lists the main detection indicators of three batches of high-whiteness resin samples, including whiteness (CIE Whiteness), yellowing index (YI), thermal decomposition temperature (T5% represents the 5% weight loss temperature in thermal gravimetric analysis), and visual appearance score. Each test is carried out in accordance with the corresponding industry or national standard (such as ASTM, GB / T, etc.), and the results are as follows:

[0180]

[0181] Whiteness (CIE Whiteness): In Example One, it has reached 96.2; in Example Two, it has reached 97.3; and in Example Three, it has further improved to 98.1, showing significant synergistic whitening and enhanced fluorescence emission effects.

[0182] Yellowing index (YI): It is significantly lower than the conventional whitening system (usually 2.0-3.5), and gradually decreases with the increase of Eu 3+ doping amount and the perfection of TiO2 photonic crystal structure, indicating that the invention has a significant effect on improving optical and thermal stability.

[0183] Thermal decomposition temperature (T5%): All three batches of samples are above 380℃; in Example Three, it reaches about 388℃, which is better than the general whitening modified PP (usually only around 360-370℃), indicating that the invention has excellent heat resistance.

[0184] Appearance quality: All three batches of samples are uniformly white, and with the strengthening of the whitening system and the perfection of ALD coating, Example Three has the best optical brightness and uniformity in visual perception.

[0185] From the above three examples and detection data, it can be seen that the high-whiteness resin preparation method described in the invention can indeed maintain excellent optical and thermal stability within a wide process window, thereby providing a reliable technical approach for industrial production of high-end whitening resin materials.

[0186] The above is only a preferred embodiment of the invention and does not limit the invention. Those skilled in the art can make usual changes and substitutions within the scope of the technical solutions of the invention, which should be included in the protection scope of the invention.

Claims

1. A method for producing a high whiteness resin, characterized by, The method comprises the following steps: S1, mesoporous SiO2@Eu is prepared respectively 3+ Whitening agents and TiO2 photonic crystal whitening agents; S2, mixing two whitening agents in a weight ratio of 1:1-1:4, surface modification, and melt blending with a resin matrix; S3, using an intelligent control system to real-time control process parameters to ensure that the whiteness is greater than or equal to 96 and the thermal decomposition temperature is greater than or equal to 380 DEG C.

2. The method according to claim 1, wherein, In step S1, mesoporous SiO2@Eu 3+ The preparation process of the whitening agent is as follows: hexadecyl trimethyl ammonium bromide is dissolved in ethanol, and mixed in a volume ratio of 4:1, and stirred at 40 DEG C for 30 minutes; ethyl silicate is added dropwise, and reacted at 40 DEG C for 6 hours, and after centrifugal washing, calcined at 560-650 DEG C for 6 hours to obtain mesoporous SiO2 with an average pore size of 2-10 nm and a specific surface area greater than or equal to 300 m2 / g; The obtained mesoporous SiO2 is immersed in a europium nitrate solution with a concentration of 0.1-0.5 mol / L and a pH value controlled at 5.5-7.5, and is ultrasonically treated for 1-3 hours to make Eu 3+ The doping amount is 1-5% of the mass of the mesoporous SiO2. After vacuum drying at 60°C, annealing was performed in the manner of keeping at 200°C for 1 hour and then increasing the temperature to 260-350°C for 2 hours, thereby obtaining Eu 3+ Mesoporous SiO2@Eu with uniform doping and fluorescent whitening effect 3+ Whitening agent.

3. The process for preparing a high brightness resin according to claim 2, characterized in that: in the step S1, the preparation process of the TiO2 photonic crystal whitening agent comprises: tetrabutyl titanate is added dropwise into the ethanol mixture, and hydrolyzed at 80 DEG C for 12 hours, and centrifuged to obtain TiO2 nanospheres with an average particle size of 180-220 nm and a particle size dispersion coefficient not more than 0.1; the TiO2 nanospheres are dispersed in a 5wt% dispersion liquid, and vertically deposited at 45 DEG C for 48 hours to form a photonic crystal film with a thickness of 5-10 microns; atomic layer deposition (ALD) is used to grow a 5nm thick SiO2 coating layer by 50 times of SiCl4 / H2O circulation at 150 DEG C, thereby obtaining the TiO2 photonic crystal whitening agent.

4. The method according to claim 3, wherein, in the step S2, when the mixed whitening agent is surface modified, the silane coupling agent is added in an amount of 3-8% of the weight of the mixed whitening agent, and the following process is used: the mixed whitening agent and the silane coupling agent are added into ethanol in a weight ratio of 3-8%, and pre-dispersed at 40 DEG C for 1-2 hours by using ultrasonic power of 200-300 W and frequency of 40 kHz; after constant temperature stirring at 60 DEG C for 3 hours, vacuum drying at 80 DEG C for 6 hours to obtain a modified material; finally, melt blending with a resin matrix at 180-220 DEG C and screw rotation speed of 150-250 rpm.

5. The method according to claim 4, wherein, a double screw extruder is used for stepwise temperature control melt blending, and the process parameters are as follows: feeding section: the resin matrix is added into the double screw extruder, and the temperature is controlled at 170-180 DEG C, the residence time is 2-3 minutes, and the screw rotation speed is 50-100 rpm; melting section 1: the material is added into the double screw extruder, and the temperature is controlled at 190-200 DEG C, the residence time is 2-3 minutes, and the screw rotation speed is 150-200 rpm; melting section 2: the temperature is controlled at 200-210 DEG C, the residence time is 3-5 minutes, and the screw rotation speed is 200-250 rpm; homogenization section: the temperature is controlled at 200-210 DEG C, the residence time is 1-2 minutes, vacuum devolatilization is set, and the screw rotation speed is 150-180 rpm; die section: the temperature is controlled at 180-190 DEG C, the residence time is 1-3 minutes, and the screw rotation speed is 80-120 rpm; In the above melt blending process, the screw torque and extrusion pressure are monitored in real time and adjusted appropriately by the intelligent control system to avoid material overheating degradation and ensure uniform dispersion of whitening agents.

6. The method for preparing a high-whiteness resin according to claim 1, characterized in that, The intelligent control system comprises: Temperature sensor and PID controller to maintain temperature fluctuations ≤ ± 1℃; Online colorimeter to detect the whiteness and yellowness index of the extruded strip at a sampling frequency of 1Hz, and dynamically adjust the mixing whitening agent ratio or extruder process parameters through feedback algorithm; Machine learning model for training and prediction based on historical batch data combined with screw torque, extrusion pressure, and vacuum degree information, to optimize whitening agent mixing ratio and processing parameters in real time.

7. The method of claim 6, wherein the high-whiteness resin is prepared by: The machine learning model is a neural network, and the input parameters include at least resin type, whitening agent ratio, processing temperature, screw torque, vacuum degree, and extrusion pressure. The output is the predicted whiteness and yellowness index, and the training weight can be updated continuously according to the collected data.

8. The method of claim 5, wherein the pH of the dispersion is adjusted to the neutral range of 6-7, and the dispersion is stirred at 50-60℃ for 0.5-1 hour to inhibit secondary agglomeration. Mesoporous SiO2@Eu 3+ The method further comprises the following steps before mixing the whitening agent and the TiO2 photonic crystal whitening agent: Mesoporous SiO2@Eu 3+ The whitening agent and the TiO2 photonic crystal whitening agent are pre-dispersed, and are dispersed in anhydrous ethanol or other low-polarity solvents. Agglomerates are dispersed by ultrasonic oscillation to ensure monodispersity. The well-dispersed powdery whitening agent is obtained by filtration or centrifugation, and the two whitening agents are mixed according to the above-mentioned ratio. The resin matrix also includes a pre-drying step before being added to the twin-screw extruder, which is to dry the resin matrix at 80-120℃ for 2-4 hours to reduce the moisture content to below 0.1%.

9. The method for preparing a high-whiteness resin according to claim 5, characterized in that, Prepared by the method of any one of claims 1-5, comprising:

10. A high brightness resin characterized in that, Resin matrix: 85-95wt%; Mixed whitening agent: 3-10wt%; Optionally, 0.1-2wt% of antioxidant is added.

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