A core-shell structure micrometer resin and a preparation method thereof

Abstract

The present application relates to the field of micron resin, to solve the problem of slow recovery speed of light diffusion performance after external force in the prior art when micron resin is used for soft light diffusion material, and provides a preparation method of core-shell structure micron resin, comprising the following steps: porous microspheres are first immersed in deionized water, and then immersed in prepolymer solution after being taken out, after first reaction, dropwise adding reaction solution, and after second reaction, micron resin is obtained; the reaction solution comprises 1,4-butanediol, bis(2-hydroxyethyl)disulfide and dibutyltin dilaurate; after polycaprolactone diol is added dropwise into hexamethylene diisocyanate-based polyisocyanate, solvent is added after reaction, and the prepolymer solution is obtained. The present application adopts hard porous core structure and shell layer structure with core-shell structure function to accelerate the recovery speed of light diffusion material under external force. The shell layer with core-shell structure function can not only buffer stress, but also can use its excellent recovery performance to assist the recovery of the light diffusion material matrix.

Description

Technical Field

[0001] This invention relates to the field of micron-sized resins, and more specifically, to a core-shell structured micron-sized resin and its preparation method. Background Technology

[0002] Micron-sized resins are commonly used in light-diffusing materials, where they are uniformly dispersed in transparent substrates such as PET, PC, and PMMA. The core of light diffusion lies in the refractive index difference between the micron-sized resin particles and the substrate resin. When light emitted from sources like LEDs shines on the light-diffusing material, the light continuously passes between the substrate and the micron-sized resin scattering particles. Due to the difference in refractive indices between the two media, the light undergoes multiple refractions, reflections, and scattering phenomena on the surface and inside the particles, thereby changing the direction of light travel and achieving uniform diffusion and softening of the light. Compared to traditional inorganic light-diffusing agents, micron-sized resins are transparent or translucent, maintaining high transmittance while achieving uniform light distribution. However, when light-diffusing materials are used on non-planar surfaces, such as curved surfaces, the substrate is often a soft material. After the film is compressed or stretched, the thickness recovery of the substrate affects the spacing between the micron-sized resin particles, thus affecting the transmittance and haze recovery of the light-diffusing material. Furthermore, the effect of pressure on the micron-sized resin can also lead to a decrease in the transmittance and haze of the light-diffusing material. Existing micron-sized resins are primarily rigid materials to ensure good structural stability and reduce the impact of structural changes on the performance of light-diffusing materials. However, when using rigid micron-sized resins, the recovery of the soft matrix after compression depends on its own recovery ability, resulting in a relatively slow recovery rate. Summary of the Invention

[0003] The purpose of this invention is to provide a core-shell structured micron-sized resin and its preparation method, thereby solving the problem that the light diffusion performance of micron-sized resins used in soft light-diffusing materials recovers slowly after being subjected to external force.

[0004] The embodiments of the present invention are achieved through the following technical solutions:

[0005] A method for preparing a core-shell structured micron-sized resin includes the following steps:

[0006] S100, methyl methacrylate and potassium persulfate aqueous solution are mixed and reacted under inert gas protection to obtain seed emulsion;

[0007] S200: After adding the mixture to the seed emulsion and allowing it to swell, the mixture is reacted under an inert gas protection, and then separated and washed to obtain porous microspheres; the mixture includes: dibutyl phthalate, polystyrene, divinylbenzene, methyl methacrylate and azobisisobutyronitrile;

[0008] S300 porous microspheres are first immersed in deionized water, then taken out and immersed in a prepolymer solution. After one reaction, a reaction solution is added dropwise, and after a second reaction, a core-shell structured micron resin is obtained. The reaction solution includes 1,4-butanediol, bis(2-hydroxyethyl) disulfide and dibutyltin dilaurate.

[0009] The preparation process of the prepolymer solution includes: adding polycaprolactone diol dropwise to hexamethylene diisocyanate-based polyisocyanate, reacting and then adding a solvent to obtain the prepolymer solution.

[0010] This invention employs a rigid, porous core structure combined with a shell structure that functions as a core-shell structure to accelerate the recovery speed of light-diffusing materials under external forces. The shell structure not only buffers stress but also utilizes its excellent recovery properties to assist the recovery of the light-diffusing material matrix. The soft matrix of the light-diffusing material often uses polydimethylsiloxane, which has a light transmittance greater than 93%, a refractive index of approximately 1.41, and exhibits excellent flexibility and elongation at break.

[0011] Potassium persulfate initiates the polymerization of methyl methacrylate (MMA) to obtain PMMA seeds. After swelling with dibutyl phthalate (DBB), the PMMA seeds allow the porogen polystyrene (PS) and crosslinking agent divinylbenzene (DBB) to penetrate the seed interior, where polymerization occurs. As the PMMA / DBB copolymer network forms, its compatibility with the porogen polystyrene decreases sharply. The polystyrene undergoes spinoline decomposition or nucleation-growth phase separation from the crosslinked network, forming polystyrene-enriched phase domains. Because the crosslinked network provides elastic constraints, phase separation is limited to the nanometer to micrometer scale; the size of the polystyrene phase domain is the final pore size. During washing, the detergent is completely miscible with DBB / PS, efficiently extracting organic matter from the pores.

[0012] Hexamethylene diisocyanate-based polyisocyanates exhibit excellent resistance to yellowing, while polycaprolactone diol, as a soft-segment polyol, provides the core-shell structure with restorative elasticity. 1,4-Butanediol acts as a hard-segment chain extender, forming hydrogen bond physical crosslinking points and improving shape retention. Bis(2-hydroxyethyl) disulfide, together with 1,4-butanediol, participates in chain extension, with dynamic crosslinking bonds located in the hard-segment region, giving the hard-segment region self-healing and remodeling properties. The introduction of HEDS not only provides dynamic disulfide bonds but also enhances the thermal stability and order of the hard-segment microregions due to its polarity, making the stationary phase less prone to fatigue degradation during repeated thermal cycling, thus making the light-diffusing material more suitable for repeated thermal cycling environments.

[0013] When synthesizing the prepolymer solution, the content of -NCO groups is reduced. This can be achieved by sampling and testing to ensure that the content is between 4.8% and 5.2% before adding solvent.

[0014] Deionized water acts as a diffusion barrier for subsequent reactions. Combined with controlled prepolymer reactivity, this ensures the prepolymer's reaction primarily occurs outside the microsphere pores. Furthermore, the prepolymer undergoes a confined, directional reaction with water at the interface, generating polyurea segments. These polyurea segments, through hydrogen bonds and mechanical interlocking, anchor the shell to the porous microsphere surface, preventing interface debonding under cyclic pressure. Using water as a diffusion barrier not only preserves the pore structure to some extent, ensuring uniform light distribution, but also improves the bonding between the shell and the microspheres.

[0015] The reason why the shell does not participate in porosity along with the microspheres is to avoid or reduce the loss of the shell's recovery ability.

[0016] The hexamethylene diisocyanate-based polyisocyanate was selected from Wanhua HT-100.

[0017] Preferably, in step S300, after the porous microspheres are immersed in deionized water, they are ultrasonically dispersed for 5-8 minutes, then kept under pressure in a vacuum environment for 25-30 minutes, and then immersed in a prepolymer solution.

[0018] The ultrasonic power is 200W, and the frequency is 40kHz. The combination of negative pressure drive and capillary force allows deionized water to fill the pores of the porous microspheres, expelling the gas inside. The cavitation rate is ≤10 kPa / s.

[0019] Preferably, in step S100, by weight, there are 8-12 parts of methyl methacrylate and 0.1-0.15 parts of potassium persulfate; the reaction temperature is 60-80℃ and the reaction time is 5-8h.

[0020] Preferably, in step S200, the mixture comprises, by weight, 3-4 parts of dibutyl phthalate, 2-3 parts of polystyrene, 1.5-2.5 parts of divinylbenzene, 5-7 parts of methyl methacrylate, and 0.2-0.3 parts of azobisisobutyronitrile.

[0021] Preferably, in step S200, the swelling temperature is 30-35℃ and the swelling time is 16-20h; the reaction adopts a gradient heating method, including: holding at 45-55℃ for 8-10h, then holding at 65-70℃ for 3.5-5h, and finally holding at 75-80℃ for 2-3h.

[0022] The decomposition rate of AIBN is highly sensitive to temperature. When rapidly heated to above 65°C, the seeds easily form a non-uniform cross-linked structure with a dense outer layer and a sparse inner layer. Therefore, this invention first maintains the temperature at a low temperature for a period of time to allow the free radicals released by AIBN to be distributed more evenly within the seeds. Then, the temperature is raised to 65-70°C, which is the main polymerization stage. It is necessary to dynamically match the polymerization rate with the PS phase separation rate as much as possible so that the network grows fast enough to freeze the size of the PS microregions formed by phase separation, without locking the phase before it is fully separated. If the temperature is too high at this stage, polymerization will complete before phase separation, and the PS will be forcibly wrapped in the network, resulting in insufficient phase separation and small and wide pore size. If the temperature is too low, the phase separation will be overly coarsened, resulting in large pore size and poor connectivity. Finally, at the 75-80°C stage, sufficient heat energy is provided to activate the chain segment movement, allowing the residual stress to fully relax at high temperature before cooling and solidification to obtain porous microspheres with a complete structure.

[0023] Preferably, the average molecular weight of polystyrene is 40k-60k.

[0024] This invention achieves pore structure control by controlling reaction parameters, pore-forming agent dosage, and molecular weight in the porous microsphere preparation process. While maintaining a narrow pore size distribution range, it also minimizes excessive mass transfer between water and the prepolymer within the pores.

[0025] Preferably, by weight, the prepolymer solution comprises 18-22 parts of polycaprolactone diol, 8-12 parts of hexamethylene diisocyanate-based polyisocyanate, and 70-110 parts of solvent; the reaction temperature of the prepolymer solution is 70-80℃, the reaction time is 2-3h, and the solvent is ethyl acetate.

[0026] The purpose of not using a catalyst in the preparation of the prepolymer solution is at least as follows: the process of hydrolysis-condensation of -NCO with pore water in the prepolymer to generate polyurea in situ and mechanically interlock it in the pores needs to be slow. Without a catalyst, the reaction rate of -NCO with water in step S300 can be reduced.

[0027] Preferably, in step S300, the temperature of the first reaction is 25-40℃ and the time is 1-3h; the temperature of the second reaction is 60-80℃ and the time is 2-4h.

[0028] The reaction solution comprises, by weight, 1-3 parts of 1,4-butanediol, 0.2-0.5 parts of bis(2-hydroxyethyl) disulfide, and 0.001-0.002 parts of dibutyltin dilaurate.

[0029] The reaction time is the holding time after the addition is completed.

[0030] The preferred reaction solution is divided into a first solution and a second solution. The first solution includes 30%-40% of 1,4-butanediol and 100% of bis(2-hydroxyethyl) disulfide; the second solution includes the remainder of 1,4-butanediol and 100% of dibutyltin dilaurate.

[0031] When adding the reaction solution, add the first solution first, then add the second solution.

[0032] The first solution further increases the density of the shell, avoids or reduces the rapid reaction of dibutyltin dilaurate with NCO and water, and also avoids the influence of the catalyst on bis(2-hydroxyethyl) disulfide.

[0033] A core-shell structured micron-sized resin prepared by the aforementioned method.

[0034] The average particle size of the core-shell structured micron-sized resin is 5-8 μm.

[0035] The present invention has at least the following beneficial effects:

[0036] This invention employs a rigid, porous core structure combined with a shell structure that functions as a core-shell structure to accelerate the recovery speed of light-diffusing materials under external forces. The shell structure not only buffers stress but also utilizes its excellent recovery properties to assist in the recovery of the light-diffusing material matrix.

[0037] Bis(2-hydroxyethyl) disulfide, together with 1,4-butanediol, participates in chain extension, and the dynamic cross-linking bonds are located in the hard segment region, giving the hard segment region self-healing and remodeling properties. The introduction of HEDS not only provides dynamic disulfide bonds, but also enhances the thermal stability and order of the hard segment microregion due to its polarity, making the stationary phase less prone to fatigue degradation during repeated thermal cycling, and making the light-diffusing material more suitable for repeated thermal cycling environments;

[0038] Deionized water acts as a diffusion barrier, and the controlled reactivity of the prepolymer ensures that the reaction of the prepolymer primarily occurs outside the microsphere pores. Furthermore, the prepolymer undergoes a confined, directional reaction with water at the interface, generating polyurea segments. These polyurea segments, through hydrogen bonds and mechanical interlocking, anchor the shell to the porous microsphere surface, preventing interface debonding under cyclic pressure. Using water as a diffusion barrier not only preserves the pore structure to a certain extent, ensuring uniform light distribution, but also improves the bonding between the shell and the microspheres. Detailed Implementation

[0039] To make the objectives, methods, and advantages of the embodiments of the present invention clearer, the methods in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0040] Example 1: A method for preparing a core-shell structured micron-sized resin, comprising the following steps:

[0041] Preparation of prepolymer solution: 6 parts of polycaprolactone diol were added dropwise to 3 parts of hexamethylene diisocyanate-based polyisocyanate, and the mixture was reacted at 70°C for 2 hours. Then, 25 parts of ethyl acetate solvent were added to obtain the prepolymer solution.

[0042] S100, 8 parts methyl methacrylate, an aqueous solution of potassium persulfate containing 0.1 parts potassium persulfate, and a NaHCO3 buffer solution containing 0.05 parts NaHCO3 were mixed and reacted under nitrogen protection (200 rpm). The resulting seed emulsion was filtered through a 200-mesh nylon screen. The reaction temperature was 60℃ and the reaction time was 5 h.

[0043] S200: After adding the mixture to the seed emulsion and swelling at 30℃ for 16h, a gradient temperature increase reaction (150rpm) was carried out under nitrogen protection: 45℃ for 10h, then 65℃ for 3.5h, and finally 75℃ for 2h. After separation: centrifugation at 4000rpm for 10min, washing three times with acetone, adding acetone, dispersing at 200W / 40kHz for 5min, soaking for 1h, centrifugation, washing twice with ethanol, adding ethanol, dispersing at 200W / 40kHz for 5min, soaking for 30min, centrifugation, washing three times with deionized water, dispersing at 200W / 40kHz for 5min, soaking for 20min, and centrifugation to obtain porous microspheres.

[0044] The mixture includes: 3 parts dibutyl phthalate, 2 parts polystyrene with an average molecular weight of 40k, 1.5 parts divinylbenzene, 5 parts methyl methacrylate, and 0.2 parts azobisisobutyronitrile;

[0045] S300 porous microspheres were first immersed in deionized water and then ultrasonically dispersed for 5 min (200W, 40KHz). They were then held under vacuum for 25 min (-90kPa), removed, and immersed in a prepolymer solution. After a first reaction at 25℃ for 1 h, the reaction solution was added dropwise. After the addition was completed, a second reaction was carried out at 60℃ for 2 h to obtain a core-shell structured micron resin.

[0046] The reaction solution includes: 1 part 1,4-butanediol, 0.2 parts bis(2-hydroxyethyl) disulfide and 0.001 parts dibutyltin dilaurate.

[0047] Example 2: A method for preparing a core-shell structured micron-sized resin, comprising the following steps:

[0048] Preparation of prepolymer solution: 8 parts of polycaprolactone diol were added dropwise to 4 parts of hexamethylene diisocyanate-based polyisocyanate, and the mixture was reacted at 80°C for 3 hours. Then, 40 parts of ethyl acetate solvent were added to obtain the prepolymer solution.

[0049] S100, 12 parts methyl methacrylate, an aqueous solution of potassium persulfate containing 0.15 parts potassium persulfate, and a NaHCO3 buffer solution containing 0.06 parts NaHCO3 were mixed and reacted under nitrogen protection (200 rpm). The resulting seed emulsion was obtained by filtering through a 200-mesh nylon screen. The reaction temperature was 80℃ and the reaction time was 8 hours.

[0050] S200: After adding the mixture to the seed emulsion and swelling at 35℃ for 20h, a gradient temperature increase reaction (150rpm) was carried out under nitrogen protection: 55℃ for 8h, then 70℃ for 5h, and finally 80℃ for 3h. After separation: centrifugation at 4000rpm for 10min, washing three times with acetone: adding acetone, dispersing at 200W / 40kHz for 5min, soaking for 1h, centrifugation, washing twice with ethanol: adding ethanol, dispersing at 200W / 40kHz for 5min, soaking for 30min, centrifugation, washing three times with deionized water: adding deionized water, dispersing at 200W / 40kHz for 5min, soaking for 20min, and centrifugation to obtain porous microspheres.

[0051] The mixture includes: 4 parts dibutyl phthalate, 3 parts polystyrene with an average molecular weight of 60k, 2.5 parts divinylbenzene, 7 parts methyl methacrylate, and 0.3 parts azobisisobutyronitrile;

[0052] S300 porous microspheres were first immersed in deionized water and then ultrasonically dispersed for 8 min (200W, 40KHz). They were then held under vacuum for 30 min (-90kPa), removed, and immersed in a prepolymer solution. After a single reaction at 40℃ for 3 h, the reaction solution was added dropwise. After the addition was completed in 1 h, a second reaction was carried out at 80℃ for 4 h to obtain a core-shell structured micron resin.

[0053] The reaction solution includes: 3 parts 1,4-butanediol, 0.5 parts bis(2-hydroxyethyl) disulfide and 0.002 parts dibutyltin dilaurate.

[0054] Example 3: A method for preparing a core-shell structured micron-sized resin, comprising the following steps:

[0055] Preparation of prepolymer solution: 7 parts of polycaprolactone diol were added dropwise to 3.5 parts of hexamethylene diisocyanate-based polyisocyanate, and the mixture was reacted at 75°C for 2.5 h. Then, 33 parts of ethyl acetate solvent were added to obtain the prepolymer solution.

[0056] S100, 10 parts methyl methacrylate, an aqueous solution of potassium persulfate containing 0.12 parts potassium persulfate, and a NaHCO3 buffer solution containing 0.05 parts NaHCO3 were mixed and reacted under nitrogen protection (200 rpm). The resulting seed emulsion was obtained by filtering through a 200-mesh nylon screen. The reaction temperature was 70℃ and the reaction time was 6 h.

[0057] S200: After adding the mixture to the seed emulsion and swelling at 32℃ for 18h, a gradient temperature increase reaction (150rpm) was carried out under nitrogen protection: 50℃ for 9h, then 68℃ for 4.5h, and finally 76℃ for 2.5h. After separation: centrifugation at 4000rpm for 10min, washing three times with acetone, adding acetone, dispersing at 200W / 40kHz for 5min, soaking for 1h, centrifugation, washing twice with ethanol, adding ethanol, dispersing at 200W / 40kHz for 5min, soaking for 30min, centrifugation, washing three times with deionized water, adding deionized water, dispersing at 200W / 40kHz for 5min, soaking for 20min, and centrifugation to obtain porous microspheres.

[0058] The mixture includes: 3.5 parts dibutyl phthalate, 2.5 parts polystyrene with an average molecular weight of 50k, 2 parts divinylbenzene, 6 parts methyl methacrylate, and 0.25 parts azobisisobutyronitrile;

[0059] S300 porous microspheres were first immersed in deionized water and then ultrasonically dispersed for 6 min (200W, 40KHz). They were then held under vacuum for 28 min (-90kPa), removed, and immersed in a prepolymer solution. After a first reaction at 30℃ for 2 h, the reaction solution was added dropwise. After the addition was completed in 1 h, a second reaction was carried out at 70℃ for 3 h to obtain a core-shell structured micron resin.

[0060] The reaction solution includes: 2 parts 1,4-butanediol, 0.35 parts bis(2-hydroxyethyl) disulfide and 0.001 parts dibutyltin dilaurate.

[0061] Example 4: The difference from Example 3 is that the reaction solution is divided into a first solution and a second solution. The first solution includes 30% 1,4-butanediol and 100% bis(2-hydroxyethyl) disulfide; the second solution includes the remainder 1,4-butanediol and 100% dibutyltin dilaurate.

[0062] When adding the reaction solution, first add the first solution, and after 0.3 hours, keep it warm for 0.9 hours. Then add the second solution, and after 0.7 hours, keep it warm for 2.1 hours.

[0063] Example 5: The difference from Example 3 is that the reaction solution is divided into a first solution and a second solution. The first solution includes 40% 1,4-butanediol and 100% bis(2-hydroxyethyl) disulfide; the second solution includes the remainder 1,4-butanediol and 100% dibutyltin dilaurate.

[0064] When adding the reaction solution, first add the first solution, and after 0.4 hours, keep it warm for 1.2 hours. Then add the second solution, and after 0.6 hours, keep it warm for 1.8 hours.

[0065] Example 6: The difference from Example 3 is that the reaction solution is divided into a first solution and a second solution. The first solution includes 35% 1,4-butanediol and 100% bis(2-hydroxyethyl) disulfide; the second solution includes the remainder 1,4-butanediol and 100% dibutyltin dilaurate.

[0066] When adding the reaction solution, first add the first solution, and after 0.35 hours, keep it warm for 1.05 hours. Then add the second solution, and after 0.65 hours, keep it warm for 1.95 hours.

[0067] Comparative Example 1: The difference from Example 6 is that the porous microspheres are not impregnated with deionized water, but directly impregnated with the prepolymer solution.

[0068] Comparative Example 2: The difference from Example 6 is that the pressure holding in a vacuum environment is changed to static placement.

[0069] Comparative Example 3: The difference from Example 6 is that 5 parts of polystyrene were used.

[0070] Comparative Example 4: The difference from Example 6 is that the average molecular weight of polystyrene is 80k.

[0071] Comparative Example 5: The difference from Example 6 is that it does not contain polystyrene.

[0072] Comparative Example 6: The difference from Example 6 is that the reaction time for the preparation of the prepolymer solution is 1 hour.

[0073] Comparative Example 7: The difference from Example 6 is that after immersion in the prepolymer solution, there is no reaction process and the reaction solution is added dropwise directly.

[0074] Comparative Example 8: The difference from Example 6 is that the first solution does not contain bis(2-hydroxyethyl) disulfide, while the second solution contains 100% bis(2-hydroxyethyl) disulfide.

[0075] Comparative Example 9: The difference from Example 6 is that the temperature of the first reaction is 65°C.

[0076] Comparative Example 10: Porous microspheres prepared using the method described in Example 6.

[0077] Experiment: Core-shell structured micron-sized resins and porous microspheres were prepared according to the preparation methods provided in Examples 1-6 and Comparative Examples 1-10. The core-shell structured micron-sized resins or porous microspheres were mixed with polydimethylsiloxane (SYLGARD 184 PDMS, containing curing agent and basic components in a mass ratio of 1:10) and coated onto a substrate. The mixture was then cured at 80°C for 1 hour and at 100°C for 0.5 hours to obtain a light-diffusing material with a thickness of 0.5 mm. The core-shell structured micron-sized resin accounted for 5 wt% of the polydimethylsiloxane. The light diffusion material was subjected to haze test (STMD1003-2013, %), transmittance test (GB / T2410-2008, %), recovery performance test: the time (s) required for haze to recover to 90% of the initial haze after stretching by 110%, and heat resistance test: 100 cycles of thermal cycling between 20℃ and 80℃, with each temperature held for 1 hour. The transmittance retention rate (A), haze retention rate (B), and yellowing index change value ΔYI were tested. The test results are shown in Table 1.

[0078] Table 1

[0079] Haze Light transmittance Recovery time A B ΔYI Example 1 88.5 91.2 3.8 94.8 95.2 0.9 Example 2 86.3 92.9 3.3 95.3 95.0 0.7 Example 3 89.7 93.4 3.2 96.1 95.8 0.6 Example 4 93.4 92.1 2.4 98.7 98.2 0.4 Example 5 94.6 91.3 2.1 98.5 98.0 0.4 Example 6 94.9 90.7 1.9 99.0 98.6 0.3 Comparative Example 1 72.3 94.0 2.3 94.7 98.2 0.4 Comparative Example 2 76.2 93.8 2.4 91.6 98.4 0.4 Comparative Example 3 84.7 90.2 2.4 96.3 96.9 0.3 Comparative Example 4 82.5 91.6 2.3 93.0 92.2 0.4 Comparative Example 5 77.3 94.1 2.2 84.7 83.0 0.3 Comparative Example 6 89.8 93.5 2.6 98.2 98.1 0.5 Comparative Example 7 93.2 92.0 2.2 87.9 90.5 0.4 Comparative Example 8 93.8 92.7 3.0 83.6 80.4 0.8 Comparative Example 9 87.5 93.9 2.3 97.8 97.2 0.4 Comparative Example 10 88.3 94.1 4.6 98.8 98.4 0.9

[0080] As can be seen from the test results of Examples 1-6, the micron-sized resin provided by the present invention has good light uniformity, light transmittance, recovery performance and heat resistance when used as a light diffusion material.

[0081] A comparison of the experimental results of Comparative Examples 1-2 and Example 6 shows that the porous structure can be maintained by impregnation with deionized water and vacuum pressure holding, which improves the haze to a certain extent. The light transmittance retention rate in Comparative Examples 1-2 also decreased to a certain extent, which may be because the debonding between the shell and the porous microspheres affected the light transmittance.

[0082] A comparison of the experimental results from Comparative Examples 3-5 and Example 6 shows that both the pore structure and pore size of the porous microspheres affect the performance of the light-diffusing material. Without polystyrene, the retention rate decreases, possibly because the debonding between the shell and the porous microspheres affects the retention rate.

[0083] A comparison of the experimental results of Comparative Example 6 and Example 6 shows that the degree of reactivity of the prepolymer also affects the performance of the light-diffusing material. This may be because the degree of reactivity of the prepolymer influences the overall diffusion tendency of the prepolymer towards the porous structure.

[0084] A comparison of the experimental results of Comparative Example 7 and Example 6 shows that the recovery performance decreases when there is no primary reaction. The reason may be that the primary reaction refers to the interfacial polymerization reaction between the prepolymer and the water in the pores of the porous microspheres, which generates a polyurea anchoring layer in situ on the surface of the microspheres. The polyurea segments are reduced, and the stability of the core-shell structure decreases.

[0085] A comparison of the experimental results of Comparative Example 8 and Example 6 shows that the timing of the addition of bis(2-hydroxyethyl) disulfide affects the retention rate.

[0086] A comparison of the experimental results of Comparative Example 9 and Example 6 shows that excessively high reaction temperatures can also affect haze. This may be because the polymerization reaction within the pore structure is enhanced, while the pore structure's stability is weakened.

[0087] A comparison of the test results of Comparative Example 10 and Example 6 shows that the material's haze and recovery performance are affected when there is no shell.

[0088] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a core-shell structured micron-sized resin, characterized in that, Includes the following steps: S100, methyl methacrylate, and potassium persulfate aqueous solution are mixed and reacted under inert gas protection to obtain a seed emulsion. S200: After adding the mixture to the seed emulsion and allowing it to swell, the mixture is reacted under an inert gas protection, and then separated and washed to obtain porous microspheres; the mixture includes: dibutyl phthalate, polystyrene, divinylbenzene, methyl methacrylate and azobisisobutyronitrile; S300 porous microspheres are first immersed in deionized water, then taken out and immersed in a prepolymer solution. After one reaction, a reaction solution is added dropwise, and after a second reaction, a core-shell structured micron resin is obtained. The reaction solution includes 1,4-butanediol, bis(2-hydroxyethyl) disulfide and dibutyltin dilaurate. The preparation process of the prepolymer solution includes: adding polycaprolactone diol dropwise to hexamethylene diisocyanate-based polyisocyanate, reacting and then adding a solvent to obtain the prepolymer solution.

2. The preparation method according to claim 1, characterized in that, In step S300, the porous microspheres are immersed in deionized water, ultrasonically dispersed for 5-8 minutes, then held under pressure in a vacuum environment for 25-30 minutes, and then immersed in a prepolymer solution.

3. The preparation method according to claim 1, characterized in that, By weight, in step S100, there are 8-12 parts of methyl methacrylate and 0.1-0.15 parts of potassium persulfate; the reaction temperature is 60-80℃ and the reaction time is 5-8h.

4. The preparation method according to claim 1, characterized in that, By weight, in step S200, the mixture comprises: 3-4 parts of dibutyl phthalate, 2-3 parts of polystyrene, 1.5-2.5 parts of divinylbenzene, 5-7 parts of methyl methacrylate, and 0.2-0.3 parts of azobisisobutyronitrile.

5. The preparation method according to claim 1, characterized in that, In step S200, the swelling temperature is 30-35℃ and the swelling time is 16-20h. The reaction adopts a gradient heating method, including: holding at 45-55℃ for 8-10h, then holding at 65-70℃ for 3.5-5h, and finally holding at 75-80℃ for 2-3h.

6. The preparation method according to claim 1, characterized in that, The average molecular weight of polystyrene is 40k-60k.

7. The preparation method according to claim 1, characterized in that, By weight, the prepolymer solution contains 6-8 parts of polycaprolactone diol, 3-4 parts of hexamethylene diisocyanate-based polyisocyanate, and 25-40 parts of solvent; the reaction temperature of the prepolymer solution is 70-80℃, the reaction time is 2-3h, and the solvent is ethyl acetate.

8. The preparation method according to claim 1, characterized in that, In step S300, the temperature of the first reaction is 25-40℃ and the time is 1-3h; the temperature of the second reaction is 60-80℃ and the time is 2-4h. The reaction solution comprises, by weight: 1-3 parts of 1,4-butanediol, 0.2-0.5 parts of bis(2-hydroxyethyl) disulfide, and 0.001-0.002 parts of dibutyltin dilaurate.

9. The preparation method according to any one of claims 1-8, characterized in that, The reaction solution is divided into a first solution and a second solution. The first solution includes 30%-40% of 1,4-butanediol and 100% of bis(2-hydroxyethyl) disulfide; the second solution includes the remainder of 1,4-butanediol and 100% of dibutyltin dilaurate. When adding the reaction solution, add the first solution first, then add the second solution.

10. A core-shell structured micron resin prepared by the preparation method according to any one of claims 1-9.