Preparation method of low-temperature glass slurry suitable for laser sealing

Abstract

The invention discloses a preparation method of low-temperature glass paste suitable for laser sealing, and relates to the technical field of electronic materials, and the preparation method comprises the following steps: mixing and stirring an organic carrier, low-melting-point glass powder and surface modified nanoparticles; carrying out rolling treatment on the mixed slurry; then defoaming the slurry to obtain glass slurry; the low-temperature glass paste comprises low-melting-point glass powder, an organic carrier and surface modified nanoparticles; the surface modified nano particles are obtained by taking at least one of metal oxides MnO, MnO2, CuO and CuO.Cr2O3 as nano particles, and carrying out surface modification treatment by using a silane coupling agent and polymer grafting; according to the low-temperature glass slurry, the laser absorption capacity of sealing glass is improved, energy can be quickly and uniformly absorbed in the laser sealing process, the sealing defect is reduced, and the airtightness of a sealed device is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic materials, and particularly relates to a preparation method of low-temperature glass paste suitable for laser sealing. BACKGROUND

[0002] Organic light-emitting device (OLED) has the characteristics of high brightness, wide viewing angle, active light-emitting, high contrast, flexibility, ultra-thin and portability, and is considered as a new generation of display technology after cathode ray tube (CRT), liquid crystal display (LCD) and plasma display (PDP). Although the performance of OLED is excellent, the organic light-emitting material is sensitive to chemical and physical environment, the device is easy to age, and the service life is short. Therefore, in order to realize large-scale production of OLED device, the problem of packaging reliability must be solved, and effective sealing must be done to isolate external water vapor and oxygen.

[0003] Low-melting-point glass sealing technology has become a popular material for OLED sealing due to its excellent chemical stability and electrical performance, low sealing temperature, easy adjustment of expansion coefficient, good air tightness of sealing, simple process and many other advantages.

[0004] In recent years, in order to reduce the influence of high temperature in the process of device sealing on electronic devices, laser sealing technology is combined with low-temperature glass paste and applied. The components using laser-assisted glass paste for sealing are usually sandwiched structures of substrate / glass paste / substrate, and the basic principle is that the whole component is perpendicular to the laser beam, the laser beam passes through the transparent upper substrate material and is directly focused on the low-melting-point glass paste, the glass paste absorbs the incident laser energy, and the packaging process is completed.

[0005] Generally, the sealing glass material has limited ability to absorb laser, so a large power laser needs to be applied, which will cause the upper and lower glass substrates to be overheated, and easily lead to deformation or breakage.

[0006] Chinese patent CN114212995B discloses a preparation method suitable for OLED sealing solder. The sealing solder prepared by the method has low sealing temperature, and the heating sealing of different wavelengths of laser from ultraviolet to infrared is realized by introducing different coloring metal ions. The main method is to directly dope MnO2, CuO, CeO2, Co2O3, etc. as metal colorants into the glass body during the preparation of glass powder, so as to improve the spectral absorption rate of the sealing glass under different wavelengths. Chinese patent CN115305035A discloses a glass adhesive for OLED sealing. The glass adhesive contains glass powder, inorganic filler, nano powder and organic carrier. Among them, 0.1%-5% nano powder is added as a high laser absorption material to promote the absorption of laser by the glass adhesive. The specific embodiment is to directly mix MnO2, CuO·Cr2O3, etc. with glass powder and organic carrier to prepare a slurry. Due to the high viscosity of the system and the high solid content, the nano powder cannot be effectively dispersed after mixing, and the laser absorption effect cannot be fully improved.

[0007] On the one hand, the introduction of different metal colorants during the preparation of low melting point glass can indeed improve the laser absorption effect of the sealing glass. However, it should be noted that the preparation of glass material requires a large number of production process equipment and high energy consumption, and it is difficult for general glass slurry using enterprises to adjust and use from the glass raw material end.

[0008] On the other hand, in the preparation process of low melting point glass slurry, nano powder is introduced as a laser absorption material. The glass powder, nano powder and organic carrier are directly mixed and used. Although the laser absorption capacity of the glass slurry can be improved by three-roll dispersion and rolling, the particle agglomeration effect of the nano powder and its poor dispersion in the glass slurry are difficult to disperse by simple stirring. SUMMARY

[0009] The embodiment of the present application provides a preparation method of low temperature glass slurry suitable for laser sealing. The nano particles treated by surface modification are mixed with glass powder and organic carrier to prepare low temperature glass slurry. Due to the existence of grafted polymer long chain segment on the surface of the modified nano particles, more steric hindrance is provided, and the agglomeration of nano particles is avoided. At the same time, the polymer chain segment existing on the surface of the nano particles can have better compatibility with the organic solvent and resin components used for preparing the slurry, which further improves the dispersity and stability of the nano particles in the slurry. Finally, the laser absorption capacity of the sealing glass is improved, so that the energy can be quickly and uniformly absorbed during the laser sealing process, the sealing defects are reduced, and the air tightness of the sealed device is improved.

[0010] The embodiment of the application provides a preparation method of low-temperature glass paste suitable for laser sealing, and specifically comprises the following steps:

[0011] ①mixing and stirring the organic carrier, the low-melting-point glass powder and the surface-modified nanoparticles;

[0012] ②carrying out rolling treatment on the mixed paste until the paste is less than 10 μm in the result of a doctor blade fineness test;

[0013] ③carrying out defoaming treatment on the paste, and thus the glass paste is obtained;

[0014] The ratio of the components of the low-temperature glass paste is as follows: the low-melting-point glass powder is 50% to 80%, the organic carrier is 20% to 50%, and the surface-modified nanoparticles are 0.5% to 8%;

[0015] The surface-modified nanoparticles are obtained by using at least one of metal oxides MnO, MnO2, CuO and CuO·Cr2O3 as the nanoparticles and carrying out surface modification treatment by using a silane coupling agent and a polymer for coating;

[0016] The surface-modified nanoparticles comprise small-diameter nanoparticles and large-diameter nanoparticles; the small-diameter nanoparticles have a particle diameter of 10-30 nm and a grafting amount of 7.9% to 10%; and the large-diameter nanoparticles have a particle diameter of 80-100 nm and a grafting amount of 5%.

[0017] Further, the low-melting-point glass powder is preferably added in an amount of 60% to 70%, and the organic carrier is preferably added in an amount of 30% to 40%.

[0018] Further, the organic carrier comprises the following components in percentage by mass: high-boiling-point organic solvent 75% to 85%, thickening agent 5% to 20%, surfactant 0.1% to 5% and thixotropic agent 0.1% to 5%.

[0019] Further, the surface-modified nanoparticles are grafted with a silane coupling agent on the surface through a coupling reaction, and then grafted with a polymer on the surface through a chemical bonding reaction, and the content of the grafted organic matter is 0.5% to 10%.

[0020] The silane coupling agent is one or more of vinyl, amino, epoxy and mercaptosiloxane coupling agents; and the polymer is one or more of acrylic resin, epoxy resin, polyurethane and unsaturated polyester.

[0021] Further, the mass ratio of the small-diameter nanoparticles to the large-diameter nanoparticles is 3:1.

[0022] Further, the small particle size nanoparticles adopt surface modified nanoparticles with a grafting amount of 7.9%, and the large particle size nanoparticles adopt surface modified nanoparticles with a grafting amount of 5%.

[0023] The one or more technical solutions provided in the embodiments of the application have at least the following technical effects or advantages:

[0024] Firstly, the laser absorption material used in the application is a nano-particle after surface modification treatment, specifically, the nano-powder of MnO, MnO2, CuO, CuO·Cr2O3, etc. is treated by coupling agent-polymer surface modification, which improves the dispersibility of the nano-powder, avoids the agglomeration effect of the nano-particle, and improves the dispersibility and stability of the nano-particle in the glass paste; the nano-particle after surface modification is mixed with glass powder and organic carrier to prepare low-temperature glass paste, which improves the laser absorption capacity of the sealing glass, enables the energy to be quickly and uniformly absorbed during laser sealing, reduces sealing defects, and improves the air tightness of the sealed device;

[0025] Secondly, by determining the relationship between the polymer grafting amount and the dispersibility, the grafting amount can be accurately controlled, thereby optimizing the dispersibility of the nano-particle in the glass paste; when a higher proportion of primary particles is required, a suitable grafting amount can be selected; when preparing the surface modified nano-particle, a suitable polymer grafting process can be selected, thereby better controlling the stability of product quality, ensuring the relative stability of the dispersibility of the nano-particle, and reducing the performance fluctuation of the product caused by the difference in dispersibility;

[0026] Thirdly, by introducing a double-particle-size synergistic structure into the surface modified nano-particle system, the optimization of laser absorption and thermal stress control is realized. Specifically, the small particle size nano-particle enhances the intrinsic absorption efficiency of the laser wavelength by virtue of the quantum size effect and the dispersion characteristics ensured by the high grafting amount; the large particle size nano-particle constructs a thermal stress buffer network through the moderate weak agglomeration induced by the 5% grafting amount. The synergistic effect of the two is that: on the optical level, a gradient refractive matching is formed, which increases the absorption rate while reducing the reflectivity; on the thermodynamic level, the energy absorption and stress dissipation are cooperated step by step, the sealing crack defects are eliminated, and the sealing air tightness and mechanical strength are synergistically improved. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 Figure 1 is a sealing line strip diagram of the application experiment 1 under the laser power of 8w;

[0028] Figure 2 Figure 1 is a sealing line strip diagram of the application experiment 1 under the laser power of 9w;

[0029] Figure 3 Figure 1 is a sealing line strip diagram of the application experiment 1 under the laser power of 10w;

[0030] Figure 4 This is a SEM image of the cross-sectional microstructure of the sealing wire in Experiment 1 of this invention at a laser power of 10W. Detailed Implementation

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to limit the invention; the term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0032] Example 1: A low-temperature glass paste suitable for laser sealing, comprising the following components by mass percentage: 50%~80% low-melting-point glass powder, 20%~50% organic carrier, and 0.5%~8% surface-modified nanoparticles;

[0033] The preferred amount of low-melting-point glass powder is 60%–70%, and the preferred amount of organic carrier is 30%–40%.

[0034] Low melting point glass powder is mainly composed of Bi2O3, B2O3, and ZnO, and at least one additive selected from metal oxides MgO, SiO2, Al2O3, Na2O, K2O, Li2O, SrO, BaO, CaO, Nd2O3, and Sb2O3.

[0035] The low-melting-point glass powder is prepared by melt water quenching according to the above composition, and has a glass transition temperature of 350~400℃ and a softening temperature of 410~450℃.

[0036] The organic carrier, by mass percentage, comprises the following components: 75%–85% organic solvent, 5%–20% thickener, 0.1%–5% surfactant, and 0.1%–5% thixotropic agent;

[0037] The organic solvent, a high-boiling-point solvent, is used to dissolve each added component, which is one or more of diethylene glycol ether acetate (butyl carbitol acetate), terpineol, and tributyl citrate.

[0038] Thickener, which improves slurry viscosity, prevents the aggregation of solid particles, and regulates slurry flowability, is composed of one or more of ethyl cellulose, nitrocellulose, polyisobutylene, and acrylic resin;

[0039] Surfactants reduce surface tension and improve the screen printing effect of pastes. They are composed of one or more of stearates, Span 85, Span 80, and lecithin.

[0040] Thixotropic agent, adjusting the interaction force of solid particles in the slurry, improving the fluidity of the slurry, preventing the slurry from agglomerating and caking, being one or a mixture of hydrogenated castor oil, bentonite, calcium silicate, colloidal alumina;

[0041] The surface modified nanoparticles are used as laser absorption materials, and the nanoparticles are at least one of MnO, MnO2, CuO, and CuO·Cr2O3.

[0042] The surface modified nanoparticles are at least one of metal oxides MnO, MnO2, CuO, and CuO·Cr2O3, and are obtained by surface modification treatment using a silane coupling agent and a polymer.

[0043] The silane coupling agent is one or more of vinyl, amino, epoxy, and mercaptosilane coupling agents, and is preferably a vinyl silane coupling agent, and is preferably γ-methacryloyloxypropyl trimethoxysilane.

[0044] The surface modified nanoparticles are grafted with the silane coupling agent on the surface through a coupling reaction, and are grafted with the polymer on the surface through a chemical bonding reaction, and the content of the grafted organic matter is 0.5% to 10%.

[0045] The preparation method of the low-temperature glass slurry specifically includes the following steps:

[0046] ①The organic carrier, the low-melting-point glass powder, and the surface modified nanoparticles are mixed and stirred;

[0047] ②The mixed slurry is subjected to rolling treatment until the slurry has a blade fineness test result of less than 5 μm;

[0048] ③The slurry is subjected to defoaming treatment, and the glass slurry is obtained;

[0049] Experiments are conducted according to the above scheme:

[0050] Experiment 1: (1) Glass powder preparation;

[0051] ①Bi2O3 (70wt%), B2O3 (10wt%), ZnO (12wt%), SiO2 (5wt%), and Al2O3 (3wt%) are weighed and then stirred and mixed in a container, and then a dry grinder is used to grind until the components are thoroughly mixed and uniform;

[0052] ②The mixed material is loaded into a quartz crucible and placed in a glass melting furnace, and then the temperature is raised to 1100℃ at a heating rate of 3℃ / min and kept for 1 hour;

[0053] ③After the end of the heat preservation process, the molten glass liquid is dropped into deionized water at a uniform and continuous speed for water quenching, and then the glass fragments are taken out and placed in a blast drying oven, which is set to 105°C for drying for 2 hours;

[0054] ④The dried glass pieces are poured into a crusher for crushing treatment with a gap of 0.05 mm, and then added to a powder screening machine for screening through a 200 mesh screen. Finally, the material is ground through an air jet mill to obtain the required glass powder;

[0055] (2) Preparation of an organic carrier;

[0056] ①Weigh the solvent pine oil (45 g) and diethylene glycol butyl ether (35 g) into a clean and dry glass bottle, stir slowly and preheat to 60°C;

[0057] ②Weigh and add ethyl cellulose (15 g), continue to stir to disperse the components completely;

[0058] ③Add lecithin (3 g) and hydrogenated castor oil (2 g), heat to 70°C and continue to stir until the components are completely dissolved. The mixture as a whole is smooth and viscous liquid;

[0059] ④Seal the glass bottle and store at room temperature to obtain the prepared organic carrier;

[0060] (3) Preparation of surface-modified nanoparticles;

[0061] ①Weigh CuO (50 g) nano powder and anhydrous ethanol (200 g) into a round-bottom flask, set the mechanical stirrer to 400 rpm for continuous stirring. Then add an appropriate amount of acetic acid solution to adjust the pH value of the system to 4-4.6. Then, add the coupling agent γ-methacryloyloxypropyltrimethoxysilane (50 g), heat to 60°C, and continue to stir for 4 hours. Finally, the CuO nanoparticles treated with the coupling agent are obtained by centrifugal precipitation. TGA test shows that the content of grafted organic matter is 2.3%;

[0062] ②Weigh the above dried CuO nanoparticles modified with silane coupling agent (50 g) and anhydrous ethanol (400 g) into a round-bottom flask, then add vinyl monomer methyl methacrylate (MMA, 50 g) and thermal initiator azobisisobutyronitrile (AIBN, 0.5 g), set the mechanical stirring to 500 rpm, then seal the system and replace the air in the system with high-purity nitrogen for 60 min. Then, heat the oil bath to 80°C, and continue to stir under nitrogen protection overnight. After the reaction is completed, the polymer-coated CuO nanoparticles are obtained by centrifugal precipitation. TGA test shows that the content of grafted organic matter is 7.9%;

[0063] (4) Preparation of low-temperature glass paste;

[0064] The low-temperature glass slurry formulation is as follows:

[0065] 35g organic carrier;

[0066] 64g of low melting point glass powder;

[0067] 1g of surface-modified CuO nanopowder;

[0068] ① Weigh the prepared organic carrier (35g), the prepared low melting point glass powder (64g), and the surface-modified CuO nanoparticles (1g) and mix them together, then use a high-speed mixer to mix and disperse them.

[0069] ② Use a three-roll mill to roll the mixed slurry until the slurry shows a fineness test result of less than 5μm.

[0070] ③The slurry is then degassed using a non-medium homogenizer to obtain glass slurry, which needs to be sealed and refrigerated for storage.

[0071] (5) Screen-printed and laser-sealed glass samples;

[0072] ① The glass substrate to be sealed is immersed in acetone and sonicated for 15 minutes, then immersed in ethanol and sonicated for 15 minutes, and then dried by blowing air at 105℃.

[0073] ② The glass slurry prepared as described in (4) is screen-printed onto the pretreated glass substrate to form the required frame lines. Then, it is placed in a muffle furnace and heated to 410-430°C at a program of 5°C / min and held for 30 min to achieve pre-sintering of the low melting point glass powder.

[0074] ③ The pre-treated glass substrate is then stacked on top of the sintered glass encapsulation layer. At the same time, a pressure of 1MPa is applied, and a laser (wavelength 808~810nm) is used at a speed of 15mm / s to melt the pre-sintered frame lines, thereby achieving bonding and completing the laser sealing.

[0075] Experiment 2 is an improvement on Example 1, wherein steps (1) and (2) remain unchanged;

[0076] (3) The operation steps are adjusted as follows:

[0077] (1) MnO (50 g) nano-powder and anhydrous ethanol (200 g) were weighed into a round-bottom flask, and a mechanical stirrer was set to 400 rpm for continuous stirring. Then, an appropriate amount of aqueous acetic acid was added to adjust the pH of the system to 4-4.6. Subsequently, a coupling agent, γ-methacryloxypropyltrimethoxysilane (50 g), was added, the temperature was raised to 60°C, and the stirring was continued for 4 hours. Finally, the coupling agent surface-treated MnO nanoparticles were obtained by centrifugal precipitation, and the TGA test showed that the grafted organic matter content was 1.8%.

[0078] (2) The above dried silane coupling agent modified MnO nanoparticles (50 g) and anhydrous ethanol (400 g) were weighed into a round-bottom flask, and then vinyl monomer methyl methacrylate (MMA, 50 g) and thermal initiator azobisisobutyronitrile (AIBN, 0.5 g) were added, and the mechanical stirring was set to 500 rpm. Then the system was sealed and high-purity nitrogen was introduced for 60 min to replace the air in the system. Then the oil bath was heated to 80°C, and the stirring was continued overnight under the protection of nitrogen. After the reaction was completed, the polymer-coated MnO nanoparticles were obtained by centrifugal precipitation, and the TGA test showed that the grafted organic matter content was 5.4%.

[0079] (4) In the low-temperature glass paste formula, the surface modified CuO nanoparticles were replaced by surface modified MnO nanoparticles, and the other conditions remained unchanged. The low-temperature glass paste formula was as follows:

[0080] Organic carrier 35 g;

[0081] Low-melting-point glass powder 64 g;

[0082] Surface modified MnO nano-powder 1 g;

[0083] The prepared sample was tested for absorbance as in Experiment 1.

[0084] Comparative Example 1:

[0085] According to Experiment 1, except that the operation step (3) was not performed, and in the low-temperature glass paste formula of (4), the surface modified nanoparticles were replaced by directly purchased CuO nano-powder, and the other conditions remained unchanged. The low-temperature glass paste formula was as follows:

[0086] Organic carrier 35 g;

[0087] Low-melting-point glass powder 64 g CuO nano-powder 1 g;

[0088] The prepared sample was tested for absorbance as in Experiment 1.

[0089] Comparative Example 2:

[0090] According to experiment two, wherein (3) is not performed, and in (4) the low-temperature glass paste formulation, the surface-modified nanoparticles are replaced with directly purchased MnO nanopowder, and the others remain unchanged. The low-temperature glass paste formulation is as follows:

[0091] Organic carrier 35 g;

[0092] Low-melting-point glass powder 64 g MnO nanopowder 1 g;

[0093] The same as experiment 1, the prepared sample is subjected to absorbance test;

[0094] Performance detection:

[0095] 1. Absorbance, using a UV-Vis-NIR spectrophotometer (PerkinElmer Lambda 1050 with an integrating sphere accessory) for the frame line after pre-sintering according to ②, using transmission reflection mode, testing its transmittance at a wavelength of 500 nm-1000 nm, and thus calculating the absorbance of the pre-sintered powder under the 810 nm laser.

[0096] 2. Sealing strength test, test method: according to “GB / T 7124-2008 Determination of tensile shear strength of adhesives”, using a universal material testing machine (Instron 5967) to test the tensile shear strength. Test conditions: sample size 10 mm × 10 mm, loading speed 1 mm / min, 5 samples per group, and taking the average value.

[0097] 3. Air tightness test, test method: helium mass spectrometry (Helium Leak Detection) according to “GB / T 15823-2009 Non-destructive testing Helium leak detection method”.

[0098] Equipment: Pfeiffer Vacuum ASM 340 helium mass spectrometer.

[0099] Test conditions: place the sealed sample in the vacuum chamber, fill helium to 1 atm, and detect the leakage rate.

[0100] Acceptance criteria: leakage rate ≤1.0 × 10 -7 Pa·m 3 / s (applicable to OLED packaging).

[0101] The test results are shown in Table 1 below;

[0102] Table 1

[0103]

[0104] From the above results, it can be seen that the use of surface modified CuO and MnO nano-powders in the glass paste respectively, compared with the direct use of CuO and MnO nano-powders, the nano-particles are more uniformly dispersed in the paste, and the absorption of the sealing glass to the wavelength of 810nm is significantly improved;

[0105] When the prepared glass paste of experiment 1 is laser sealed, the sealing is carried out under the conditions of laser power of 8w, 9w and 10w respectively, and the sealing conditions are as shown in Figure 1 、 Figure 2 and Figure 3 ; at the same time, for the sealing condition under the laser power of 10w, the SEM observation of the cross-sectional micro-morphology of the line is as shown in Figure 4 .

[0106] The technical solutions in the above embodiments of the present application have at least the following technical effects or advantages:

[0107] The unmodified nano-particles are easy to form large-size agglomerates due to high surface energy and lack of dispersion stability mechanism, the particles in the agglomerates are tightly combined, and it is difficult to completely disperse them by conventional mechanical stirring or three-roll grinding; the nano-particles tend to form local high-concentration areas in the organic carrier, and are enriched on the surface of glass powder particles or the polar regions of the organic carrier; the agglomerates are easy to concentrate in the weak shear force area during the preparation of the paste, such as the edge of the container or the dead zone of the paste flow, resulting in uneven distribution; the long-chain segments of the polymer are introduced by surface modification treatment in the present embodiment, which effectively inhibits the van der Waals force between the nano-particles through steric hindrance effect, and significantly reduces the agglomeration phenomenon; the silane coupling agent grafts polar groups on the surface of the nano-particles through chemical bonding, which enhances the compatibility with the organic solvent; the polymer coating further provides steric hindrance to inhibit agglomeration; the modified nano-particles are uniformly distributed in the glass paste in the form of primary particles or small-size agglomerates, the nano-particles are well dispersed in the organic carrier, the compatibility with the organic solvent is improved, and local enrichment at the interface between the glass powder and the organic carrier is avoided; in the overall matrix of the glass paste, the nano-particles are uniformly distributed, and there is no obvious phase separation or aggregation area; the modified nano-particles form a stable colloidal system in the paste, which improves the effective specific surface area of the laser absorbing material, thereby significantly enhancing the absorption capacity of the sealing layer to the laser energy;

[0108] The laser absorbing material used in the present embodiment is a nano-particle after surface modification treatment, specifically, the nano-powders of MnO, MnO2, CuO, CuO·Cr2O3, etc. are treated by coupling agent-polymer surface modification, which improves the dispersibility of the nano-powder, avoids the agglomeration effect of the nano-particles, and improves the dispersibility and stability of the nano-particles in the glass paste;

[0109] In the embodiment, the surface-modified nanoparticles are mixed with glass powder and an organic carrier to prepare a low-temperature glass paste, which improves the laser absorption capacity of the sealing glass, enables rapid and uniform absorption of energy during laser sealing, reduces sealing defects, and improves the air tightness of the sealed device.

[0110] In the above embodiment one, the surface modification of the nanoparticles improves the dispersibility of the nanopowder, avoids the agglomeration of the nanoparticles, improves the dispersibility and stability of the nanoparticles in the glass paste, enables rapid and uniform absorption of energy during laser sealing, reduces sealing defects, and improves the air tightness of the sealed device. To further improve the energy absorption of laser sealing, the embodiment one is further improved.

[0111] The surface-modified nanoparticles in the above experiment are subjected to dispersibility detection, and Zeta potential analysis detection is performed by Malvern Zetasizer Ultra.

[0112] The surface-modified nanoparticle agglomerates are detected to have the size distribution shown in Table 2:

[0113] Table 2

[0114]

[0115] On the basis of experiment 1, experiments are performed on different polymer grafting amounts, and the grafting amount ranges are: 0% (unmodified), 2%, 5%, 7.9% (experiment 1), and 10%. The experimental results are shown in Table 3:

[0116] Table 3

[0117]

[0118] The grafting amount is positively correlated with the proportion of the original particles. With each 1% increase in the grafting amount, the proportion of the original particles increases by 3%. With each 1% increase in the grafting amount, the proportion of large agglomerates decreases by 40%, and the proportion of small agglomerates (50-100 nm) increases with the increase in the grafting amount. The polymer chain inhibits large agglomeration but allows weak binding. The proportion of medium agglomerates (100-200 nm) first increases and then decreases. When the grafting amount is 2%-5%, part of the agglomeration is inhibited, and when the grafting amount is 5%, further dispersion is achieved.

[0119] The technical solutions in the above embodiments of the present application have at least the following technical effects or advantages:

[0120] As the polymer grafting amount increases from 0% to 10%, the proportion of primary particles (<50 nm) increases from <1% to 23%, and the proportion of large agglomerates (>200 nm) decreases from 87% to 0%, indicating that the grafting amount is positively correlated with the dispersity, the thickness of the polymer coating layer increases with the grafting amount, providing a stronger steric hindrance effect, effectively inhibiting the agglomeration caused by van der Waals force, and the polarity matching degree between the polymer chain segment and the organic carrier is improved, reducing the phase separation between the nanoparticles and the matrix;

[0121] The proportion of small agglomerates increases with the increase of the grafting amount, from 3% when the grafting amount is 0% (unmodified) to 70% when the grafting amount is 10%, indicating that the polymer chain inhibits the formation of large agglomerates, but allows the nanoparticles to form small agglomerates in a weakly bound manner; the proportion of medium-sized agglomerates first increases and then decreases, when the grafting amount is 2%-5%, part of the agglomeration is inhibited but new medium-sized agglomerates are formed, resulting in an increase in the proportion; when the grafting amount exceeds 5%, the nanoparticles are further dispersed, and the proportion of medium-sized agglomerates decreases;

[0122] By determining the relationship between the polymer grafting amount and the dispersity, the grafting amount can be accurately controlled, thereby optimizing the dispersity of the nanoparticles in the glass paste, and when a higher proportion of primary particles is required, a suitable grafting amount can be selected; in the preparation of surface-modified nanoparticles, a suitable polymer grafting process can be selected, thereby better controlling the stability of product quality, ensuring the relative stability of nanoparticle dispersity, and reducing product performance fluctuations caused by dispersity differences.

[0123] Example Three: The above-mentioned Example Two determines the relationship between the polymer grafting amount and the dispersity, accurately controls the grafting amount, thereby optimizing the dispersity of the nanoparticles in the glass paste, regulates the laser sealing process, thereby achieving performance optimization of the low-temperature glass paste and improvement of the laser sealing quality, and further improves the performance of the low-temperature glass paste and the laser sealing quality on the basis of Example Two.

[0124] The grafting amount of the nanoparticles is different, including nanoparticles with a grafting amount of 7.9%-10% and nanoparticles with a grafting amount of 5%;

[0125] The experiment of the present embodiment is carried out on the basis of Experiment 1, as Experiment 1-1. The difference between Experiment 1-1 and Experiment 1 is that the surface-modified CuO nanoparticles used in Experiment 1-1 include nanoparticles with a grafting amount of 7.9% and nanoparticles with a grafting amount of 5%, which are compounded in a mass ratio of 3:1; the particle size of the nanoparticles is 10-30 nm; and the experimental results are shown in Table 4 below;

[0126] Table 4

[0127]

[0128] The nanoparticles also include small particle sizes of 10-30 nm and large particle sizes of 80-100 nm;

[0129] The grafting amount of the small particle size nanoparticles is 7.9%-10% (to ensure high dispersibility);

[0130] The grafting amount of the large particle size nanoparticles is 5% (to allow moderate agglomeration to disperse thermal stress);

[0131] The mass ratio of the small particle size to the large particle size nanoparticles is 3:1.

[0132] Experiments 1-2 were conducted based on experiments 1-1 for this embodiment. The difference between experiments 1-2 and experiments 1-1 is that the surface-modified CuO nanoparticles used in experiments 1-2 are compounded in a mass ratio of 3:1 from small particle sizes (10-30 nm, grafting amount 7.9%) and large particle sizes (80-100 nm, grafting amount 5%). The experimental results are shown in Table 5 below;

[0133] Table 5

[0134]

[0135] The technical solutions in the embodiments of the present application have at least the following technical effects or advantages:

[0136] The small particle size nanoparticles enhance the laser energy capture capability through quantum size effect. After the surface is modified by a high grafting amount of 7.9%-10%, a dense polymer coating layer is formed to inhibit particle agglomeration, so that the nanoparticles are uniformly dispersed in the slurry matrix in the original size, the high dispersibility greatly improves the specific surface area, and the intrinsic absorption efficiency of the sealing layer to the laser wavelength laser is further increased;

[0137] The grafting amount of 5% of the large particle size nanoparticles forms a "semi-naked" surface structure, allowing the particles to construct a micron-sized agglomeration network through weak van der Waals forces. The micron-sized agglomerates construct a stress buffer network in the sealing layer, which absorbs thermal expansion stress through micro-plastic deformation, triggers grain boundary sliding deformation during the high-temperature expansion stage of laser sealing, effectively absorbs local thermal stress, and this controllable weak agglomeration behavior becomes a key buffer mechanism for the anti-cracking of the sealing layer;

[0138] The dual-particle-size system further improves the performance through optical and thermodynamic synergy. The small particle size dominates the intrinsic energy absorption, and the large particle size suppresses the interface light reflection. The two form a gradient refractive matching layer to optimize the light path transmission efficiency. The small particle size quickly converts laser energy into heat energy and triggers sealing, and the large particle size dissipates stress through sliding deformation at the peak value of thermal expansion;

[0139] By introducing a dual-particle-size synergistic structure into the surface-modified nanoparticle system, the optimization of laser absorption and thermal stress control is realized. Specifically, small-particle-size nanoparticles enhance the intrinsic absorption efficiency of the laser wavelength by virtue of the quantum size effect and the dispersion characteristics ensured by a high grafting amount; large-particle-size nanoparticles build a thermal stress buffer network through moderate weak agglomeration induced by a 5% grafting amount. The synergistic effect of the two is embodied in the following aspects: on the optical level, a gradient refractive matching is formed to increase the absorption rate while reducing the reflectivity; on the thermodynamic level, step-by-step synergy of energy absorption and stress dissipation is realized to eliminate the sealing crack defects and achieve the synergistic improvement of the sealing airtightness and mechanical strength.

[0140] The preferred embodiments of the present application are described above, but the present application is not limited to the above. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a low temperature glass frit suitable for laser sealing, characterized in that, Specifically comprising the following steps: ①mixing and stirring the organic carrier, low-melting glass powder and surface-modified nanoparticles; ②rolling the mixed slurry until the blade fineness test result of the slurry is less than 10 μm; ③defoaming the slurry to obtain the glass slurry; The ratio of the components of the low-temperature glass slurry is: low-melting glass powder 50%~80%, organic carrier 20%~50% and surface-modified nanoparticles 0.5%~8%; The surface-modified nanoparticles are obtained by using at least one of metal oxides MnO, MnO2, CuO and CuO·Cr2O3 as nanoparticles and performing surface modification treatment using silane coupling agent and polymer coating; The surface-modified nanoparticles include small-particle-size nanoparticles and large-particle-size nanoparticles; the small-particle-size nanoparticles have a particle size of 10-30 nm and a grafting amount of 7.9%~10%; the large-particle-size nanoparticles have a particle size of 80-100 nm and a grafting amount of 5%.

2. The method of claim 1, wherein the low temperature glass paste suitable for laser sealing is prepared by the steps of: The preferred amount of the low-melting glass powder is 60%~70%, and the preferred amount of the organic carrier is 30%~40%.

3. The method of claim 1, wherein the low temperature glass paste suitable for laser sealing is prepared by the steps of: The organic carrier comprises the following components by mass percentage: high-boiling organic solvent 75%~85%, thickening agent 5%~20%, surfactant 0.1%~5% and thixotropic agent 0.1%~5%.

4. The method for preparing a low-temperature glass paste suitable for laser sealing as described in claim 1, characterized in that, The surface-modified nanoparticles are grafted with silane coupling agent on the surface through coupling reaction, and then grafted with polymer on the surface through chemical bonding reaction, and the content of the grafted organic matter is 0.5%~10%; The silane coupling agent is one or more of vinyl, amino, epoxy and mercaptosiloxane coupling agents; and the polymer is one or more of acrylic resin, epoxy resin, polyurethane and unsaturated polyester.

5. The method of claim 1, wherein the low temperature glass paste suitable for laser sealing is prepared by the steps of: The mass ratio of the small-particle-size nanoparticles to the large-particle-size nanoparticles is 3:

1.

6. The method of claim 1, wherein the low temperature glass paste suitable for laser sealing is prepared by the steps of: The small-particle-size nanoparticles use surface-modified nanoparticles with a grafting amount of 7.9%, and the large-particle-size nanoparticles use surface-modified nanoparticles with a grafting amount of 5%.

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