A photocurable silicone resin and a preparation method and application thereof

Abstract

This invention discloses a photocurable silicone resin, its preparation method, and its applications. The silicone resin provided by this invention possesses an acryloyloxy group, a photosensitive group that allows for rapid photocuring; it also contains phenyl and disulfide bonds, which can synergistically regulate the refractive index of the silicone resin; furthermore, the disulfide bonds undergo a metathesis reaction under ultraviolet irradiation, effectively reducing the curing shrinkage rate. The cured silicone resin of this invention exhibits good transparency, refractive index, and adhesive strength, making it suitable for electronic device encapsulation.

Description

Technical Field

[0001] This invention relates to the field of polymer compound technology, and more specifically, to a photocurable silicone resin, its preparation method, and its application. Background Technology

[0002] With the rapid development of high-power LEDs, performance requirements for LED packaging materials have also been put forward, including high transparency, high refractive index, low shrinkage, and resistance to yellowing. Currently, the most commonly used LED packaging materials include epoxy resin and silicone materials. However, epoxy resin has defects such as poor moisture resistance, poor radiation resistance, easy yellowing, and easy brittleness. Therefore, a lot of research has begun to focus on silicone packaging materials with good heat resistance, aging resistance, and yellowing resistance.

[0003] Existing technology proposes an epoxy phenyl vinyl silicone resin prepared by sol-gel condensation using methyl vinyl dimethoxysilane, diphenylsilanediol, and 3-glycidylpropyl(dimethoxy)methylsilane as raw materials. Benefiting from its functional groups, this epoxy-modified silicone resin exhibits excellent optical transparency (visible light region >90%), high refractive index (1.55), high heat resistance, and good adhesion after thermosetting. Furthermore, its properties remain largely unchanged after heat and UV aging, making it suitable as an adhesion promoter for LED encapsulation materials. However, this technology requires high-temperature molding and does not meet the requirement for rapid curing.

[0004] Existing technology also proposes a high-refractive-index silicone resin, obtained by hydrolysis of methylphenyldimethoxysilane, methylvinyldimethoxysilane, and γ-methacryloyloxypropylmethyldimethoxysilane, which exhibits a high refractive index. However, acrylate resins suffer from curing shrinkage, and the aforementioned solutions do not address this defect.

[0005] Currently, most LED encapsulation materials on the market are thermosetting materials, which are time-consuming and energy-intensive. Photocurable acrylic optical adhesives suffer from high curing shrinkage rates, typically exceeding 8%, due to the rapid changes in intermolecular spacing during the rapid curing process. Therefore, the preparation of silicone resins that simultaneously possess high curing speed, high refractive index, low curing shrinkage, and good temperature resistance is an urgent need in this field. Summary of the Invention

[0006] In order to overcome the shortcomings of existing technologies, such as slow curing speed, low refractive index, large curing shrinkage rate, and poor high temperature resistance, the primary objective of this invention is to provide a photocurable silicone resin.

[0007] Another object of the present invention is to provide a method for preparing a photocurable silicone resin.

[0008] Another object of the present invention is to provide an application of the above-described photocurable silicone resin or the photocurable silicone resin prepared by the above-described preparation method in the preparation of electronic components.

[0009] Another object of the present invention is to provide a photocurable silicone adhesive with adjustable refractive index and shrinkage.

[0010] Another object of the present invention is to provide an application of the above-mentioned photocurable silicone adhesive with adjustable refractive index and shrinkage in the preparation of electronic components.

[0011] The above-mentioned objective of the present invention is achieved through the following technical solution:

[0012] This invention provides a photocurable silicone resin, the general structural formula of which is shown in Formula I:

[0013]

[0014] R1 is selected from methyl, phenyl, or... At least one of them;

[0015] R2 is selected from methyl or At least one of them;

[0016] n is selected from 1 or 2.

[0017] In the aforementioned photocurable silicone resin, the acryloyloxy group contains an active double bond, which can undergo an addition reaction under ultraviolet irradiation for rapid curing. The sulfur atom possesses a high molar refractive index, and the phenyl group also exhibits a high ratio of dielectric polarizability to molar volume; their synergistic effect achieves a high refractive index. Furthermore, the disulfide bonds gradually break and recombine under ultraviolet irradiation (365 nm), increasing the free volume of the polymer network, reducing volume shrinkage, and releasing shrinkage stress. The prepolymer crosslinks into a three-dimensional polymer under ultraviolet irradiation, resulting in enhanced cohesion and good adhesion to electronic components.

[0018] The synergistic effect of phenyl groups and disulfide bonds can achieve high refractive indices, with the phenyl content contributing more to the refractive index than the disulfide bond content. However, phenyl groups have significant steric hindrance; as the phenyl content increases, this steric hindrance hinders the condensation reaction, reducing the degree of Si-O-Si bond condensation and resulting in a silicone resin viscosity that does not reach the desired level. This invention adjusts the content of phenyl groups and disulfide bonds to obtain a high-refractive-index silicone resin with appropriate Si-O-Si condensation degree and viscosity.

[0019] Preferably, the degree of condensation of the Si-O-Si chain segments in the photocurable silicone resin is 5-100.

[0020] Preferably, the viscosity of the photocurable silicone resin at 25°C is 600-30000 mPa·s; more preferably, the viscosity of the photocurable silicone resin at 25°C is 1000-15000 mPa·s.

[0021] The aforementioned photocurable silicone resin is formed by the condensation reaction between silane-oxygen bonds of phenyl-containing organosilanes, acryloyloxy-containing organosilanes, and disulfide-containing organosilanes. Any two of the three organosilanes, or a single organosilane itself, can undergo the aforementioned condensation reaction. It may be a polymer chain residue formed after the condensation reaction of any one or more of the above three organosilanes through the silane-oxygen bond.

[0022] Preferably, in formulas I, R1, and R2 It is a residue formed by the condensation reaction between an alkoxy group and a phenyl-containing organosilane, an acryloxy-containing organosilane, or a disulfide-containing organosilane through a silane-oxygen bond.

[0023] Preferably, the phenyl-containing organosilane is selected from at least one of the following: siloxanes containing at least one phenyl substituent and at least one alkoxy substituent; cyclosiloxanes containing at least one phenyl substituent and having 3 to 5 silicon atoms on the ring; and / or;

[0024] The acryloyloxy-containing organosilane is a siloxane containing at least one acryloyloxypropyl substituent and at least one alkoxy substituent; and / or;

[0025] The organosilane containing disulfide bonds is a bissilane organic coupling agent containing 1 to 2 disulfide bonds.

[0026] Preferably, the organosilane containing disulfide bonds is selected from one or two of bis(γ-triethoxysilylpropyl)tetrasulfide and bis(γ-triethoxysilylpropyl)disulfide.

[0027] Preferably, the phenyl-containing organosilane is selected from one or more of methylphenyldimethoxysilane, methylphenyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, methyldiphenylethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, octaphenylcyclotetrasiloxane, trimethyltriphenylcyclotrisiloxane, tetramethyltetraphenylcyclotetrasiloxane, and pentamethylpentaphenylcyclopentasiloxane.

[0028] Preferably, the organosilane containing acryloyloxy group is selected from one or more of 3-methacryloyloxypropylmethyldimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, and acryloyloxypropyltrimethoxysilane.

[0029] Another object of the present invention is to provide a method for preparing a photocurable silicone resin, comprising the following steps:

[0030] S1 involves hydrolyzing a phenyl-containing organosilane, an acryloxy-containing organosilane, and an acid catalyst in a solvent to obtain an intermediate product.

[0031] S2, add an organosilane containing a disulfide bond to the above intermediate product to react with it, adjust the pH to neutral, remove the solvent, and obtain the photocurable organosilicon resin.

[0032] Preferably, the phenyl-containing organosilane is selected from at least one of the following: siloxanes containing at least one phenyl substituent and at least one alkoxy substituent; cyclosiloxanes containing at least one phenyl substituent and having 3 to 5 silicon atoms on the ring; and / or;

[0033] The acryloyloxy-containing organosilane is a siloxane containing at least one acryloyloxypropyl substituent and at least one alkoxy substituent; and / or;

[0034] The organosilane containing disulfide bonds is a bissilane organic coupling agent containing 1 to 2 disulfide bonds.

[0035] Preferably, the organosilane containing disulfide bonds is selected from one or two of bis(γ-triethoxysilylpropyl)tetrasulfide and bis(γ-triethoxysilylpropyl)disulfide.

[0036] Preferably, the phenyl-containing organosilane is selected from one or more of methylphenyldimethoxysilane, methylphenyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, methyldiphenylethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, octaphenylcyclotetrasiloxane, trimethyltriphenylcyclotrisiloxane, tetramethyltetraphenylcyclotetrasiloxane, and pentamethylpentaphenylcyclopentasiloxane.

[0037] Preferably, the organosilane containing acryloyloxy group is selected from one or more of 3-methacryloyloxypropylmethyldimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, and acryloyloxypropyltrimethoxysilane.

[0038] It can be seen that the photocurable silicone resin is made by hydrolysis and condensation of organosilanes containing acryloyloxy groups, organosilanes containing phenyl groups, and organosilanes containing disulfide bonds. By adjusting the feeding ratio of the three functional organosilanes, an effective combination of high refractive index and low curing shrinkage can be achieved.

[0039] Preferably, the molar ratio of the phenyl-containing organosilane, the acryloxy-containing organosilane, and the disulfide-containing organosilane is (0.4–2.4):(0.2–1.0):(0.05–1.2). More preferably, the molar ratio of the phenyl-containing organosilane, the acryloxy-containing organosilane, and the disulfide-containing organosilane is (0.8–1.4):(0.4–1.0):(0.2–0.6).

[0040] Preferably, the acid catalyst includes one or more of concentrated hydrochloric acid, concentrated sulfuric acid, p-toluenesulfonic acid, trifluoromethanesulfonic acid, acetic acid, cation exchange resin, dibutyltin dilaurate, and dibutyltin diacetate.

[0041] Preferably, the solvent is water, an alcohol, or a mixture of both. More preferably, the alcohol is one or more selected from methanol, ethanol, propanol, and butanol.

[0042] Preferably, the temperature of the hydrolysis reaction in step S1 is 25–70°C; and the time of the hydrolysis reaction in step S1 is 1–5 hours.

[0043] Preferably, the hydrolysis reaction in step S1 is carried out under stirring.

[0044] Preferably, the reaction temperature in step S2 is 30–60°C; the reaction time in step S2 is 1–3 hours.

[0045] Preferably, the reaction in step S2 is carried out under stirring.

[0046] Preferably, the reagent used to adjust the pH to neutral in step S2 is an inorganic base. More preferably, the inorganic base is selected from one or more of sodium bicarbonate, ammonium bicarbonate, sodium carbonate, potassium carbonate, ammonium sulfite, ammonium bisulfite, ammonia, ammonium hydroxide, and sodium hydroxide.

[0047] Preferably, the solvent removal method used in step S2 is vacuum distillation. Preferably, the pressure of vacuum distillation is 0.05 MPa to 0.01 MPa, the distillation temperature is 25°C to 70°C, and the distillation time is 0.5 to 5 hours.

[0048] Preferably, the raw materials for the hydrolysis reaction in step S1 further include monofunctional organosilanes.

[0049] To adjust the terminal hydroxyl groups of the molecular chain, this invention can also add a monofunctional organosilane as an M-segment end-capping agent during the hydrolysis reaction. The more M-segments added, the more silanyl-terminated molecular chain ends there are, and the lower the silanyl content will be. This invention preferably uses the type and proportion of monofunctional organosilanes to adjust the silanyl content, thereby enabling the use of silanyl groups to provide appropriate adhesion to the substrate.

[0050] Preferably, the monofunctional organosilane is selected from one or two of hexamethyldisiloxane and hexaethyldisiloxane.

[0051] Preferably, the molar ratio of the phenyl-containing organosilane to the monofunctional organosilane is (0.4–2.4):(0–0.4). More preferably, the molar ratio of the phenyl-containing organosilane to the monofunctional organosilane is (0.8–1.4):(0–0.4).

[0052] Another object of the present invention is to provide an application of the above-described photocurable silicone resin or the photocurable silicone resin prepared by the above-described preparation method in the preparation of electronic components.

[0053] Preferably, the electronic component is a Mini LED.

[0054] Another object of the present invention is to provide a photocurable silicone adhesive comprising the following raw materials in parts by weight: 100 parts of the above-mentioned photocurable silicone resin and 0.5-3 parts of photoinitiator.

[0055] Preferably, the photocurable silicone adhesive comprises the following raw materials in parts by weight: 100 parts of photocurable silicone resin and 2-3 parts of photoinitiator.

[0056] Preferably, the photoinitiator includes one or more of the following: photoinitiator TPO-L, photoinitiator 1173, photoinitiator TPO, photoinitiator 819, photoinitiator 184, photoinitiator benzophenone, and photoinitiator ITX.

[0057] Another object of the present invention is to provide an application of the above-mentioned photocurable silicone adhesive in the preparation of electronic components.

[0058] Preferably, the electronic component is a Mini LED.

[0059] Another object of the present invention is to provide an electronic component comprising the above-mentioned photocurable silicone adhesive.

[0060] Preferably, the electronic component is a Mini LED.

[0061] Compared with the prior art, the beneficial effects of the present invention are:

[0062] This invention provides a photocurable silicone resin, in which an acryloyloxy group containing a photosensitive double bond is introduced into the molecular structure, enabling the matrix resin to be cured by ultraviolet light, thereby significantly improving the curing speed. The phenyl and disulfide bonds in the molecule synergistically contribute to a good refractive index, and the viscosity of the silicone resin is controlled, resulting in a silicone resin with a high refractive index. During ultraviolet curing, the disulfide bonds gradually break and undergo metathesis reaction, increasing the free volume of the polymer network, reducing volume shrinkage and releasing shrinkage stress, and regulating the polymer network structure.

[0063] This invention provides a method for preparing photocurable silicone resin. The silicone resin prepared by hydrolysis condensation has incompletely condensed hydroxyl groups at the ends of the molecules, ensuring that it has a certain adhesion to the substrate.

[0064] This invention provides a photocurable silicone adhesive with adjustable refractive index and shrinkage rate. It features rapid curing speed, maintains good transparency and thermal stability after curing, exhibits excellent adhesion to substrates such as glass, steel, and iron, achieves a tensile shear strength of up to 1.5 MPa, has a refractive index higher than 1.5, and a curing shrinkage rate of less than 5%, lower than that of free radical-based acrylic UV adhesives (typically above 8%). Based on the adhesive's excellent transparency, refractive index, and adhesion, it can be used as a topcoat for Mini LED screen protection without affecting the LED's luminescence or original color. Furthermore, thermal aging tests show no significant decrease in brightness after seven days of aging. Attached Figure Description

[0065] Figure 1 The Fourier transform infrared (FTIR) spectrum of the photocurable silicone resin in Example 1 is shown.

[0066] Figure 2 The 1H NMR spectrum of the photocurable silicone resin in Example 1 ( 1 H NMR spectrum.

[0067] Figure 3 The image shows the Raman spectrum of the photocurable silicone resin in Example 1.

[0068] Figure 4 The UV transmittance spectra of the photocurable silicone resins in each embodiment and comparative example are shown.

[0069] Figure 5 The images show the thermal decomposition (TGA) spectra of the photocurable silicone resins in each embodiment and comparative example.

[0070] Figure 6 , 7 The photorheological test curing shrinkage spectra of the photocurable silicone resins in Examples 1-4 and the comparative examples are shown.

[0071] Figure 8The tensile shear strength diagrams of the photocurable silicone resin in Example 1 on different substrates are shown.

[0072] Figure 9 This is a schematic diagram of the surface coating encapsulation of a Mini LED using the photocurable silicone resin of Example 5.

[0073] Figure 10 The CIE chromaticity diagram of the Mini LED encapsulated using the photocurable silicone resin and commercial thermocurable AB adhesive from Example 5 is shown.

[0074] Figure 11 Normalized electroluminescence spectra of Mini LEDs after dual 85 aging for different times after encapsulation using Example 5.

[0075] Figure 12 Normalized electroluminescence spectra of Mini LEDs after dual 85 aging for different times following AB encapsulation using commercial thermosetting technology. Detailed Implementation

[0076] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in this embodiment are conventional reagents, methods and equipment in this technical field.

[0077] The viscosity testing method of this invention is as follows: A rotational rheometer (model HAAKE MARS 60) from Thermo Fisher Scientific, USA, was used. The test conditions were: a 20mm diameter flat rotor, a temperature set at 25℃, a balancing time of 2 minutes, and a rotational speed range of 0.01–1000 s. -1 .

[0078] Example 1

[0079] A photocurable silicone resin has the following general structural formula:

[0080]

[0081] A method for preparing a photocurable silicone resin includes the following steps:

[0082] 145.84 g of methylphenyldimethoxysilane (0.8 mol), 92.94 g of 3-methacryloyloxypropylmethyldimethoxysilane (0.4 mol), 3 g of concentrated hydrochloric acid, and 30 g of deionized water were added to a flask. A stirrer, thermometer, and condenser were provided. The mixture was stirred at 60 °C for 2 h, then cooled to 25 °C. 94.96 g of Si75 (0.2 mol) was slowly added dropwise through a constant pressure funnel, and the reaction was allowed to proceed for 3 h. NaHCO3 was added to neutralize the pH to 6–7. The mixture was extracted with dichloromethane (DCM) and then distilled under reduced pressure at 40 °C to obtain a colorless and transparent photocurable silicone resin. The viscosity was measured to be 1260 mPa·s, and the refractive index was 1.514. This resin was designated as photocurable resin 1.

[0083] Example 2

[0084] A photocurable silicone resin has the following general structural formula:

[0085]

[0086] A method for preparing a photocurable silicone resin includes the following steps:

[0087] 244.36 g of diphenyldimethoxysilane (1.0 mol), 156.24 g of 3-methacryloyloxypropylmethyldiethoxysilane (0.6 mol), 16.24 g of hexamethyldisiloxane (0.1 mol), 4 g of trifluoromethanesulfonic acid, and 42 g of deionized water were added to a flask. A stirrer, thermometer, and condenser were provided. The mixture was kept at 55 °C with stirring for 1 h. The temperature was then lowered to 10 °C, and 134.74 g of Si69 (0.25 mol) was added dropwise using a constant pressure funnel. After the addition was complete, the mixture was kept at 30 °C for 3 h. After the reaction was complete, NaHCO3 was added to neutralize the pH to 6–7. The mixture was then distilled under reduced pressure at 55 °C to obtain a colorless and transparent photocurable silicone resin with a viscosity of 9762 mPa·s and a refractive index of 1.527. This resin was designated as photocurable resin 2.

[0088] Example 3

[0089] A photocurable silicone resin has the following general structural formula:

[0090]

[0091] A method for preparing a photocurable silicone resin includes the following steps:

[0092] 277.61 g of phenyltrimethoxysilane (1.4 mol), 248.35 g of 3-methacryloyloxypropyltrimethoxysilane (1.0 mol), 6.87 g of acetic acid, and 65 g of deionized water were added to a flask. A stirrer, thermometer, and condenser were provided. The mixture was kept at 50 °C with stirring for 2.5 h. The temperature was then lowered to 20 °C, and 161.69 g of Si69 (0.3 mol) was added dropwise using a constant pressure funnel. After the addition was complete, the mixture was stirred for another 2 h. After the reaction was complete, NaHCO3 was added to neutralize the pH to 6–7. The mixture was then distilled under reduced pressure at 60 °C to obtain a colorless and transparent photocurable silicone resin. The viscosity was measured to be 6044 mPa·s, and the refractive index was 1.520. This resin was designated as photocurable resin 3.

[0093] Example 4

[0094] A photocurable silicone resin has the following general structural formula:

[0095]

[0096] A method for preparing a photocurable silicone resin includes the following steps:

[0097] 326.89 g of diphenyldiethoxysilane (1.2 mol), 232.34 g of 3-methacryloyloxypropyltriethoxysilane (0.8 mol), 8.4 g of concentrated hydrochloric acid, and 75 g of deionized water were added to a flask and stirred at 40 °C for 2 h. The mixture was then cooled to 5 °C, and 284.89 g of Si75 (0.6 mol) was slowly added dropwise through a constant pressure funnel. The mixture was then heated to 30 °C and kept at that temperature for 2 h. NaHCO3 was added to neutralize the pH to 6–7. The mixture was extracted with DCM and then distilled under reduced pressure at 40 °C to obtain a pale yellow, transparent photocurable silicone resin. The viscosity was measured to be 13440 mPa·s, and the refractive index was 1.535. This resin was designated as photocurable resin 4.

[0098] Comparative Example 1

[0099] A photocurable silicone resin, essentially the same as in Example 1, differs in that it lacks the addition of methylphenyldimethoxysilane. The general structural formula of the photocurable silicone resin (SASR) is as follows:

[0100]

[0101] The resulting product was a colorless, transparent, oily liquid with a measured viscosity of 511 mPa·s and a refractive index of 1.454, and was designated as photocurable resin 5.

[0102] Comparative Example 2

[0103] A photocurable silicone resin, basically the same as in Example 1, except that it lacks Si75 as an ingredient. The general structural formula of the photocurable silicone resin (PASR) is as follows:

[0104]

[0105] The resulting product was a colorless, transparent, oily liquid with a measured viscosity of 335 mPa·s and a refractive index of 1.493, and was designated as photocurable resin 6.

[0106] Examples 5-10

[0107] A photocurable silicone adhesive with adjustable refractive index and shrinkage rate was prepared using photocurable silicone resins from Examples 1-4 and Comparative Examples 1-2, and its components are shown in Table 1.

[0108] Table 1. Components (parts by weight) of Examples 5-10

[0109] Example 5 6 7 8 9 10 UV-cured resin 1 100 - - - - - UV-cured resin 2 - 100 - - - - UV-cured resin 3 - - 100 - - - UV-cured resin 4 - - - 100 - - UV-cured resin 5 - - - - 100 - UV-cured resin 6 - - - - - 100 Photoinitiator TPO-L 2 - 2.5 - - 2 Photoinitiator 1173 - 2 - 2.5 2 -

[0110] Performance testing

[0111] 1. Structural characterization

[0112] Taking the photocurable silicone resin (SPASR) of Example 1 as an example, this invention characterized the molecular structure of the photocurable silicone resin using Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, and microconfocal Raman spectroscopy. The results are as follows: Figure 1-3 As shown.

[0113] Reference Figure 1 The FTIR spectrum of SPASR resin shows several characteristic peaks, including: at 2959 cm⁻¹. -1 2895cm -1 The peak at 1720 cm⁻¹ is the characteristic absorption peak of the stretching vibration of CH on methyl and methylene groups. -1 The characteristic absorption peak for the stretching vibration of CO is located at 1640 cm⁻¹. -1 The characteristic absorption peak for the stretching vibration of C=C is located at 1260 cm⁻¹. -1 The characteristic absorption peak for the bending vibration of Si-CH3 is located at 1000–1150 cm⁻¹. -1 The characteristic absorption peak for the stretching vibration of Si-O-Si is located at 3496 cm⁻¹. -1 The characteristic absorption peak of Si-OH is located at 3000–3100 cm⁻¹. -1 The characteristic peaks of stretching vibration of CH on the benzene ring appeared at 680–880 cm⁻¹. -1 An absorption peak for the out-of-plane bending vibration of the benzene ring (CH) was observed at [location].

[0114] Reference Figure 2 of1 The H NMR spectrum shows characteristic peaks at 5.98 and 5.42 ppm for the -C=C hydrogen atom on the acryloyloxy group in KH-571, characteristic peaks at 3.98, 1.12, and 0.49 ppm for the -CH2- hydrogen atom on the acryloyloxy group, characteristic peak at 1.81 ppm for the hydrogen atom on the methyl group connected to the double bond, characteristic peak at 0.02 ppm for the proton on the Si-CH3 group generated after MM capping, characteristic peaks at 7.24 ppm and 7.49 ppm for the hydrogen atom on the benzene ring in methylphenyldimethoxy, characteristic peak at 2.56 ppm for the hydrogen atom on the carbon group connected to the sulfur atom, and characteristic peak of active hydrogen at 5.17 ppm.

[0115] Reference Figure 3 Raman spectrum, 506cm -1 The characteristic peak at 620 cm⁻¹ belongs to the SS bond. -1 The characteristic peak at 695 cm⁻¹ belongs to the CS bond, while the peak at 695 cm⁻¹ belongs to the CS bond. -1 The peak at this location represents the bending vibration peak of the carbon skeleton of the benzene ring.

[0116] Based on the infrared, Raman, and NMR spectra above, it can be seen that the photocurable silicone resin of Example 1 showed characteristic peaks of acryloyloxy, phenyl, disulfide bonds, and the silicon-oxy-silicon skeleton, indicating the successful synthesis of the silicone resin product.

[0117] 2. Transparency Characterization

[0118] To characterize the transparency of the photocurable high-temperature resistant silicone adhesives of Examples 5-10, the present invention uses an ultraviolet spectrophotometer to measure the transmittance in the wavelength range of 400-800nm ​​according to the test method of ASTM D1003-13, with a film thickness of 120μm.

[0119] The results are as follows Figure 4 As shown, it can be seen that the transmittance of the samples in Examples 5-8 all exceeded 90% in the range of 400-800nm, which indicates that the obtained photocurable silicone resin has good transparency in the visible light region.

[0120] 3. Characterization of heat resistance properties

[0121] The heat resistance of the photocurable silicone resins in each embodiment was tested using a thermogravimetric analyzer.

[0122] The obtained TGA spectrum is as follows Figure 5 As shown, the temperature (T) under different weight losses was then statistically analyzed. 5％ T max ) and weight retention rate at 800℃ (Y) 800 The results are shown in Table 2.

[0123] Table 2. TGA spectral analysis results of different embodiments

[0124] <![CDATA[T 5％ (℃)]]> <![CDATA[T max (℃)]]> <![CDATA[Y 800 (%)]]> Example 5 269 431 41.92 Example 6 266 429 48.43 Example 7 280 430 49.43 Example 8 257 430 54.28 Example 9 160 269 18.45 Example 10 271 427 29.20

[0125] As shown in Table 2, the photocurable silicone resin T of the present invention... 5％ Above 250℃, this indicates no significant weight change within that temperature range; significant weight loss only occurs at temperatures above 410℃; and at 800℃, it retains 41.92%-54.28% of its residual weight, demonstrating excellent high-temperature resistance. In contrast, Comparative Examples 1-2 exhibit decreased high-temperature resistance due to the lack of rigid, high-temperature-resistant benzene rings or multifunctional disulfide-bonded organosilanes providing crosslinking points in their molecular structures.

[0126] 4. Curing shrinkage rate test

[0127] Photorheological tests were performed using a rotational rheometer (model: HAAKE MARS60) from Thermo Fisher Scientific, USA. A constant stress mode was selected, with a fixed shear stress τ0 of 0 Pa, an oscillation frequency of 1 Hz, a gap of 0.2 mm, a normal force |Fn| of 0 N, and thermal gap compensation enabled when the complex modulus |G*| < 12 Pa. The irradiance was 30 mW / cm². 2 The test duration was 300 seconds. A 365nm wavelength UV point light source was activated at approximately 100 seconds, with a data acquisition interval of 1 second. The stress applied to the sample by the fixed rotor was monitored, and the change in the distance between the rotor and the platform during polymerization was recorded. The formula for calculating the volume shrinkage ratio is shown in Equation 2.

[0128]

[0129] Photorheological test results are as follows Figure 6 As shown, the curing shrinkage rate spectrum is as follows: Figure 7As shown, Example 10 (without Si75) exhibited the highest curing shrinkage rate at 7.98%, which is closely related to its high conversion rate. This indicates that a large number of acryloyloxy groups polymerized shortly after irradiation, an unavoidable defect in free radical polymerization systems. The curing shrinkage rates of Examples 5-9 remained below 5%, with slight variations due to differences in curing kinetics, but still lower than that of Example 10. This reflects the metathesis reaction of disulfide bonds during UV irradiation. Under UV irradiation, the cleavage rate of disulfide bonds is lower than the initial photopolymerization rate of the photoinitiator, allowing for the gradual breaking of disulfide bonds during rapid photopolymerization. This increases the free volume of the polymer network, reduces volume shrinkage, and releases shrinkage stress. Compared to free radical UV adhesives, especially acrylates, which typically have a volume shrinkage rate above 8%, the photocurable silicone resin containing disulfide bonds prepared in this invention can effectively control the curing shrinkage rate below 5%, providing a new approach to reducing volume shrinkage and adjusting the polymer network structure.

[0130] 5. Adhesion performance tests on different substrates

[0131] The photocurable silicone adhesive from Example 5 was used to test the adhesion strength on different metal surfaces and polymeric organic materials. The adhesion strength test was conducted using the same method as described above according to the GB / T 7124-2008 test standard. The results are as follows: Figure 8 As shown in Table 3.

[0132] Table 3 shows the bonding performance of the adhesive in Example 5 on different substrates.

[0133] substrate Glass Fe Al Bond strength / MPa 1.84±0.13 2.17±0.18 1.96±0.09 substrate PVC PMMA PS Bond strength / MPa 0.71±0.03 0.68±0.04 0.70±0.05

[0134] Reference Figure 8 As shown in Table 5, the silicone adhesive with adjustable refractive index and shrinkage of the present invention exhibits good adhesion properties on various metal surfaces and polymeric organic materials, with particularly impressive adhesion properties on iron, aluminum, and glass surfaces.

[0135] 6. Mini LED Packaging Testing

[0136] A glass-based Mini LED board was selected as the substrate, and the coating from Example 5 was applied to its surface. The coating thickness was 200 μm, and after photocuring, it was used as a protective adhesive for Mini LED screens. Figure 9 As shown. After encapsulation, a double 85% damp heat aging test was conducted to measure the change in gloss. A commercial AB adhesive was used as a control; components A and B were mixed at a weight ratio of 10:1, degassed, coated, and cured at 150℃ for 1 hour. Figure 10 The image shows the chromaticity of the Mini LED beads after encapsulation, indicating that the adhesive applied after top coating did not affect their light emission. Figure 11 and Figure 12 The images show the spectra of Example 5 and the commercial AB adhesive after encapsulation and aging, respectively. As can be seen from the images, after 7 days of aging with double 85, the spectral amplitude of Example 5 decreased to 81.12%, while that of the commercial thermosetting AB adhesive decreased to 82.06%, indicating that the photocurable silicone adhesive prepared by this invention has good encapsulation potential.

[0137] The above embodiments are preferred experimental methods of the present invention, but the implementation of the present invention is not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a photocurable silicone resin, characterized in that, Includes the following steps: S1 involves hydrolyzing a phenyl-containing organosilane, an acryloxy-containing organosilane, and an acid catalyst in a solvent to obtain an intermediate product. S2, add an organosilane containing a disulfide bond to the above intermediate product to react with it, adjust the pH to neutral, remove the solvent, and obtain the photocurable organosilicon resin. The molar ratio of the phenyl-containing organosilane, the acryloxy-containing organosilane, and the disulfide-containing organosilane is (1.2-1.4):(0.8-1.0):(0.3-0.6).

2. The preparation method according to claim 1, characterized in that, The disulfide-containing organosilane is selected from bis(γ-)silanes. Triethoxysilylpropyl)tetrasulfide, bis(γ-) One or two of the triethoxysilylpropyl disulfide; wherein the phenyl-containing organosilane is selected from one or more of methylphenyldimethoxysilane, methylphenyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, octaphenylcyclotetrasiloxane, trimethyltriphenylcyclotrisiloxane, tetramethyltetraphenylcyclotetrasiloxane, and pentamethylpentaphenylcyclopentasiloxane.

3. The preparation method according to claim 1, characterized in that, The acryloyloxy group containing the organosilane is selected from one or more of 3-methacryloyloxypropylmethyldimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, and acryloyloxypropyltrimethoxysilane.

4. The preparation method according to claim 1, characterized in that, The degree of condensation of the Si-O-Si chain segments in the photocurable silicone resin is 5-100; and / or, the viscosity of the photocurable silicone resin at 25°C is 600-30000 mPa·s.

5. The application of the photocurable silicone resin prepared by the preparation method according to any one of claims 1-4 in the preparation of photocurable silicone adhesives.

6. A photocurable silicone adhesive, characterized in that, The raw materials include the following parts by weight: 100 parts of photocurable silicone resin prepared by the preparation method according to any one of claims 1-4, and 0.5-3 parts of photoinitiator.

7. The photocurable silicone adhesive according to claim 6, characterized in that, The photoinitiator is selected from one or more of the following: photoinitiator TPO-L, photoinitiator 1173, photoinitiator TPO, photoinitiator 819, photoinitiator 184, photoinitiator benzophenone, and photoinitiator ITX.

8. The application of the photocurable silicone adhesive according to any one of claims 6-7 in the preparation of electronic components.

9. An electronic component, characterized in that, Contains the photocurable silicone adhesive as described in any one of claims 6-7.

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