Low-temperature stable high-thixotropy ultraviolet light and heat dual-curing adhesive as well as preparation method and application thereof

Abstract

The invention discloses a low-temperature stable high-thixotropy ultraviolet light and heat dual-curing adhesive as well as a preparation method and application thereof. The low-temperature stable high-thixotropy ultraviolet light and heat dual-curing adhesive comprises the following raw material components in parts by weight: 15-25 parts of high-transmittance epoxy acrylate; 15 to 25 parts of hydroxyl-terminated polycaprolactone; 37 to 58 parts of a composite thixotropic agent; 2 to 4.5 parts of a composite photoinitiator; 3 to 6 parts of blocked isocyanate; 0.5 to 1.2 parts of a silane coupling agent; 0.2 to 0.5 part of an antioxidant; 0.1 to 0.3 part of an ultraviolet absorbent; the composite thixotropic agent is prepared by compounding ultra-pure modified spherical silicon dioxide and low-haze hydrophobic fumed silica according to a mass ratio of (11-26): 1. Through cooperation of the composite thixotropic agent, the high-transmittance epoxy acrylate, the hydroxyl-terminated polycaprolactone and other components, the thixotropic adhesive has excellent optical performance, wide-temperature thixotropic stability and storage and production adaptability.

Description

Technical Field

[0001] This invention belongs to the field of adhesive technology, and relates to a low-temperature stable, high-thixotropic, ultraviolet photothermal dual-curing adhesive, its preparation method, and its application. Background Technology

[0002] With the rapid development of intelligent driving and high-definition imaging technology, camera modules need to have both high light transmittance and impact resistance. Radar packaging needs to be compatible with wide temperature conditions of -40~85℃ and electromagnetic compatibility requirements. Existing UV photothermal dual-curing adhesives have the following shortcomings in this field: (1) It is difficult to balance thixotropy and light transmittance: single fumed silica thixotropic agent is easy to cause the adhesive haze to increase (>2%), which affects the optical performance of the camera; single spherical silica thixotropic efficiency is low, and high addition (>10%) will increase radar signal attenuation (insertion loss > 0.5dB); Insufficient wide temperature performance: The thixotropic network is prone to collapse at low temperature (-40℃) (thixotropic index <2.5), and overflow of adhesive will contaminate the lens / antenna during application; After curing at high temperature (85℃), it is prone to aging and yellowing (yellowing index >1.5), resulting in camera imaging distortion and radar signal stability decline; (2) Poor compatibility of photothermal curing: When non-latent thermosetting agents coexist with photoinitiators, they are prone to pre-reaction during the encapsulation resting period (room temperature storage <1 month), resulting in abnormally high adhesive viscosity, which cannot meet the long-cycle production requirements of camera / radar batch encapsulation.

[0003] Chinese invention patent application number 202211384239.4 discloses a dual-curing adhesive and its preparation method. The dual-curing adhesive, in a total of 100 parts by weight, comprises 30-55 parts epoxy acrylate, 30-50 parts dual-curing oligomer, 10-30 parts epoxy acrylate diluent, 1-3 parts cationic photoinitiator, 2-4 parts free radical initiator, 0.1-0.5 parts photosensitizer, 0.5-2 parts coupling agent, 0.5-2 parts hydrophobic material, and 0.05-0.3 parts dispersant. This dual-curing adhesive significantly increases the crosslinking density of the adhesive, resulting in a significant improvement in the sealing and waterproofing performance after curing. However, it cannot meet the requirements for mass packaging of cameras / radar systems. Summary of the Invention

[0004] In order to solve the above-mentioned technical problems, the purpose of this invention is to provide a low-temperature stable, high-thixotropic, ultraviolet photothermal dual-curing adhesive.

[0005] To achieve the above objectives, the present invention provides a low-temperature stable, high-thixotropic, UV-thermal dual-curing adhesive, comprising the following raw material components in parts by weight: 15-25 parts of high-transmittance epoxy acrylate; 15-25 parts of hydroxyl-terminated polycaprolactone; 37-58 parts of composite thixotropic agent; 2-4.5 parts of composite photoinitiator; 3-6 parts of blocked isocyanate; 0.5-1.2 parts of silane coupling agent; Antioxidant 0.2~0.5 parts; 0.1 to 0.3 parts of ultraviolet absorber; The composite thixotropic agent is a mixture of ultrapure modified spherical silica and low-haze hydrophobic fumed silica in a mass ratio of 11 to 26:1.

[0006] Ideally, the high-transmittance epoxy acrylate has a transmittance of ≥93% at 780nm and an epoxy value of 0.5~0.6eq / 100g.

[0007] Ideally, the number-average molecular weight of the terminal hydroxyl polycaprolactone is 1500-2500.

[0008] Optimally, the composite photoinitiator is a mixture of 2-hydroxy-2-methyl-1-phenyl-1-propanone and benzophenone in a mass ratio of 2-3:1. Ideally, the blocked isocyanate is an ε-caprolactam-blocked MDI trimer with a deblocking temperature of 80~100℃ and a yellowing index ≤0.8 after aging at 85℃ for 1000h.

[0009] Ideally, the ultrapure modified spherical silica has a particle size of 1-3 μm, and the low-haze hydrophobic fumed silica has a specific surface area of ​​200-300 m². 2 / g, haze contribution ≤0.5%.

[0010] Another object of the present invention is to provide a method for preparing the above-mentioned low-temperature stable high thixotropic ultraviolet photothermal dual-curing adhesive, comprising the following steps: (a) Pretreatment of composite thixotropic agent: The composite thixotropic agent of the formulation amount is stirred and mixed with the silane coupling agent (partially or completely) to obtain a pre-dispersed thixotropic agent; (b) Blending of matrix resin: The high-transmittance epoxy acrylate and the terminal hydroxyl polycaprolactone are mixed at 75~85°C to obtain a blended resin; (c) Composite preparation: Add the pre-dispersed thixotropic agent to the blended resin of step (b), stir and mix, and then add the formulated amount of the composite photoinitiator, blocked isocyanate, antioxidant and ultraviolet absorber (the remaining silane coupling agent may also be added), mix and stir, then degas under vacuum and cool in the dark.

[0011] Another object of the present invention is to provide an application of the above-mentioned low-temperature stable high thixotropic ultraviolet photothermal dual-curing adhesive, characterized in that it is used for the encapsulation or bonding of cameras and radars.

[0012] Ideally, it is used for bonding camera lenses to mounts, fixing camera CMOS chips to substrates, sealing radar radomes, and bonding radar chips to substrates, with an application environment temperature of -40~85℃.

[0013] This invention relates to a low-temperature stable, high-thixotropic, UV-curable, and photothermal dual-curing adhesive. Through the combination of a composite thixotropic agent, high-transmittance epoxy acrylate, and hydroxyl-terminated polycaprolactone, it exhibits excellent optical properties (transmittance ≥92%@780nm, haze ≤1.0%), wide-temperature thixotropic stability (thixotropic index ≥4.0 at -40℃, thixotropic index ≥5.2 at 25℃, and thixotropic index ≥4.8 at 85℃), and adaptability to storage and production (room temperature, light-protected storage period ≥6.5 months (no thixotropic agent sedimentation, no pre-curing), and volume shrinkage ≤1.8% after photothermal dual curing). It meets the optical requirements for camera lens bonding, ensures radar signal insertion loss <0.2dB, and adapts to the electromagnetic compatibility requirements of radar packaging. After 30 minutes of application... No excess adhesive, packaging yield ≥99% under wide temperature range; yellowing index ≤1.2 after high temperature aging (85℃×1000h), shear strength retention ≥90%; and avoids camera lens shift and radar antenna radome deformation.

[0014] The low-temperature stable high thixotropic ultraviolet photothermal dual-curing adhesive of this invention has good process compatibility. The adhesive has a bonding strength of ≥15MPa with camera glass / plastic lenses and radar aluminum alloy / plastic antenna covers. Moreover, the curing process is compatible with existing SMT packaging production lines and no new equipment is required. Detailed Implementation

[0015] This invention relates to a low-temperature stable, high-thixotropic, UV-curable, photothermal dual-curing adhesive, comprising the following raw material components in parts by weight: 15-25 parts of high-transmittance epoxy acrylate; 15-25 parts of hydroxyl-terminated polycaprolactone (PCL-OH); 37-58 parts of composite thixotropic agent; 2-4.5 parts of composite photoinitiator; 3-6 parts of blocked isocyanate; 0.5-1.2 parts of silane coupling agent; 0.2-0.5 parts of antioxidant; and 0.1-0.3 parts of UV absorber. The composite thixotropic agent is a mixture of ultrapure modified spherical silica and low-haze hydrophobic fumed silica at a mass ratio of 11-26:1. This low-temperature stable, high-thixotropic, UV-curable, and photothermal dual-curing adhesive, through the combination of composite thixotropic agents, high-transmittance epoxy acrylate, and hydroxyl-terminated polycaprolactone, exhibits excellent optical properties (transmittance ≥92%@780nm, haze ≤1.0%), wide-temperature thixotropic stability (thixotropic index ≥4.0 at -40℃, thixotropic index ≥5.2 at 25℃, and thixotropic index ≥4.8 at 85℃), and adaptability to storage and production (room temperature, light-protected storage period ≥6.5 months (no thixotropic agent sedimentation, no pre-curing), and volume shrinkage ≤1.8% after photothermal dual curing). It meets the optical requirements for camera lens bonding, reduces radar signal insertion loss to <0.2dB, and is compatible with the electromagnetic compatibility requirements of radar packaging. After 30 minutes of application... No excess adhesive, packaging yield ≥99% under wide temperature range; yellowing index ≤1.2 after high temperature aging (85℃×1000h), shear strength retention ≥90%; and avoids camera lens shift and radar antenna radome deformation.

[0016] This invention relates to a low-temperature stable, high-thixotropic, UV-curable, and photothermal dual-curing adhesive. Through the combination of a composite thixotropic agent, high-transmittance epoxy acrylate, and hydroxyl-terminated polycaprolactone, it exhibits excellent optical properties (transmittance ≥92%@780nm, haze ≤1.0%), wide-temperature thixotropic stability (thixotropic index ≥4.0 at -40℃, thixotropic index ≥5.2 at 25℃, and thixotropic index ≥4.8 at 85℃), and adaptability to storage and production (room temperature, light-protected storage period ≥6.5 months (no thixotropic agent sedimentation, no pre-curing), and volume shrinkage ≤1.8% after photothermal dual curing). It meets the optical requirements for camera lens bonding, ensures radar signal insertion loss <0.2dB, and adapts to the electromagnetic compatibility requirements of radar packaging. After 30 minutes of application... It exhibits no adhesive overflow and achieves a packaging yield of ≥99% under wide temperature conditions; after high-temperature aging (85℃×1000h), the yellowing index is ≤1.2, and the shear strength retention rate is ≥90%; it also avoids camera lens misalignment and radar radome deformation. Moreover, the combination of ultrapure modified spherical silica and low-haze hydrophobic fumed silica not only reduces the scattering of light by impurities and lowers the haze caused by agglomeration, but also constructs a "point-to-surface interwoven" thixotropic network (thixotropic index ≥4.0 at -40℃), resulting in an adhesive transmittance ≥92%@780nm and haze ≤1.0%, meeting the optical requirements of cameras. At the same time, the low addition amount avoids radar signal attenuation (insertion loss < 0.2dB).

[0017] The low-temperature stable high thixotropic ultraviolet photothermal dual-curing adhesive of this invention has good process compatibility. The adhesive has a bonding strength of ≥15MPa with camera glass / plastic lenses and radar aluminum alloy / plastic antenna covers. Moreover, the curing process is compatible with existing SMT packaging production lines and no new equipment is required.

[0018] The high-transmittance epoxy acrylate (EA) has a transmittance of ≥93% at 780nm and an epoxy value of 0.5~0.6 eq / 100g. The terminal hydroxyl polycaprolactone has a number-average molecular weight of 1500~2500 and a yellowing index ≤0.5. The composite photoinitiator is a mixture of 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173) and benzophenone (BP) in a mass ratio of 2~3:1. The blocked isocyanate is an ε-caprolactam-blocked MDI trimer with a deblocking temperature of 80~100℃ and a yellowing index ≤0.8 after aging at 85℃ for 1000h. The ultrapure modified spherical silica has a particle size of 1~3μm, and the low-haze hydrophobic fumed silica has a specific surface area of ​​200~300m². 2 / g, haze contribution ≤0.5%.

[0019] The preparation method of the above-mentioned low-temperature stable high thixotropic UV photothermal dual-curing adhesive includes the following steps: (a) pretreatment of composite thixotropic agent: the composite thixotropic agent of the formula amount is stirred and mixed with the silane coupling agent (partially or completely) to obtain a pre-dispersed thixotropic agent; (b) blending of matrix resin: the high-transmittance epoxy acrylate of the formula amount is stirred and mixed with the hydroxyl-terminated polycaprolactone at 75~85℃ to obtain a blended resin; (c) composite preparation: the pre-dispersed thixotropic agent is added to the blended resin of step (b), stirred and mixed, and then the composite photoinitiator, blocked isocyanate, antioxidant and UV absorber of the formula amount are added (the remaining silane coupling agent may also be added), mixed and stirred, vacuum degassing, and cooled in the dark.

[0020] The aforementioned low-temperature stable, high-thixotropic, UV-curable, and photothermal dual-curing adhesive is used for the encapsulation or bonding of cameras and radars. It is preferably used for bonding camera lenses to mounts, fixing camera CMOS chips to substrates, sealing radar radomes, and bonding radar chips to substrates, with an application environment temperature of -40 to 85°C.

[0021] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art under the premise of equivalent changes and modifications should fall within the protection scope of the present invention. Example 1

[0022] This embodiment provides a low-temperature stable, high-thixotropic, UV-thermal dual-curing adhesive and its preparation method, as detailed below: (a) Pretreatment of composite thixotropic agent: 35 kg of ultrapure modified spherical silica (particle size 2 μm, Evonik AEROSIL 812S), 2.5 kg of low haze hydrophobic fumed silica (TOKUSIL 2000HD) and 0.5 kg of KH-560 were stirred in a high-speed mixer at 1500 r / min for 15 min to obtain a pre-dispersed thixotropic agent; (b) Blending of matrix resin: 25 kg of high-transmittance EA (transmittance 93.5%@780nm, Nan Ya NPES-901, epoxy value 0.48±0.02eq / 100g) and 20 kg of PCL-OH (molecular weight 2000, Perrun PCL-2000) were added to a double planetary stirrer and stirred at 80℃ for 30 min to obtain blended resin, and then cooled to 50℃; (c) Composite preparation: Add the pre-dispersed thixotropic agent from step (a) to the blended resin from step (b) and stir at 1200 r / min for 40 min; then add the composite photoinitiator (2 kg 1173, 1 kg BP), 4 kg blocked isocyanate (Bayer Desmodur BL 3175), 0.7 kg KH-560, 0.3 kg 1010 and 0.2 kg UV absorber UV-531 in sequence, continue stirring at 50℃ and 1000 r / min for 20 min, degas under vacuum at -0.09 MPa for 30 min, and cool to room temperature in the dark.

[0023] The obtained product will undergo the following performance tests (camera lens bonding and adaptation): Curing: Irradiate with 365nm ultraviolet light (800mW / cm²) for 40s, then heat at 85℃ for 25min; Performance: Light transmittance 92.8%@780nm, haze 0.8%; thixotropic index 4.4 at -40℃, thixotropic index 5.3 at 25℃; adhesion strength to glass lens 16.2MPa; yellowing index 1.0 after aging at 85℃×1000h, shear strength retention rate 92%; no delamination after 7.5 months of storage at room temperature. Example 2

[0024] This embodiment provides a low-temperature stable, high-thixotropic, UV-thermal dual-curing adhesive and its preparation method, as detailed below: (a) Pretreatment of composite thixotropic agent: 40 kg of ultrapure modified spherical silica (3 μm particle size, Shenna SQ-3), 2 kg of low haze hydrophobic fumed silica (Tokuyama TOKUSIL 2000HD) and 0.6 kg of KH-560 were stirred in a high-speed mixer at 1500 r / min for 18 min to obtain a pre-dispersed thixotropic agent; (b) Blending of matrix resin: 20 kg of high-transmittance EA (transmittance 93.5%@780nm, Nanya NPES-901, epoxy value 0.48±0.02eq / 100g) and 18 kg of PCL-OH (molecular weight 2500, Shenzhen Guanghua Weiye PCL - diol 2500) were added to a double planetary stirrer and stirred at 80℃ for 30 min to obtain blended resin, and then cooled to 50℃; (c) Composite preparation: Add the pre-dispersed thixotropic agent from step (a) to the blended resin from step (b) and stir at 1200 r / min for 40 min; then add the composite photoinitiator (2.5 kg 1173, 1.2 kg BP), 5 kg blocked isocyanate (Bayer Desmodur BL 3175), 0.8 kg KH-560, 0.4 kg 1010 and 0.3 kg UV absorber UV-531 in sequence, continue stirring at 50℃ and 1000 r / min for 25 min, degas under vacuum at -0.09 MPa for 30 min, and cool to room temperature in the dark.

[0025] The obtained product will undergo the following performance tests (radar radome sealing and fitting): Curing: Irradiate with 365nm ultraviolet light (850mW / cm²) for 35s, then heat at 90℃ for 22min; Performance: Radar signal insertion loss 0.15dB; thixotropic index 4.6 at -40℃, thixotropic index 5.6 at 25℃; bonding strength with aluminum alloy radome 15.8MPa; shear strength retention rate 93% after aging at 85℃ for 1000h; no delamination after 8 months of storage at room temperature. Example 3

[0026] This embodiment provides a low-temperature stable, high-thixotropic, UV-thermal dual-curing adhesive and its preparation method, as detailed below: (a) Pretreatment of composite thixotropic agent: 33 kg of ultrapure modified spherical silica (particle size 2 μm, Evonik AEROSILR812S), 2 kg of low haze hydrophobic fumed silica (Tokuyama TOKUSIL 2000HD) and 0.4 kg of KH-560 were stirred in a high-speed mixer at 1500 r / min for 12 min to obtain a pre-dispersed thixotropic agent; (b) Blending of matrix resin: 18 kg of high-transmittance EA (transmittance 93.5%@780nm, Nanya NPES-901, epoxy value 0.48±0.02eq / 100g) and 25 kg of PCL-OH (molecular weight 1800, Daicel, Japan) were added to a double planetary stirrer and stirred at 80℃ for 30 min to obtain blended resin, and then cooled to 50℃; (c) Composite preparation: Add the pre-dispersed thixotropic agent from step (a) to the blended resin from step (b) and stir at 1200 r / min for 38 min; then add the composite photoinitiator (1.8 kg 1173, 0.8 kg BP), 4.5 kg blocked isocyanate (Bayer Desmodur BL 3175), 0.6 kg KH-560, 0.3 kg 1010 and 0.15 kg UV absorber UV-531 in sequence, continue stirring at 50℃ and 1000 r / min for 22 min, degas under vacuum at -0.09 MPa for 30 min, and cool to room temperature in the dark.

[0027] The obtained product will undergo the following performance tests (camera CMOS chip fixed): Curing: Irradiate with 365nm ultraviolet light (750mW / cm²) for 45s, then heat at 88℃ for 24min; Performance: Volume shrinkage rate 1.6%; thixotropic index 4.5 at -40℃, thixotropic index 5.4 at 25℃; adhesion strength to CMOS chip 17.1MPa; yellowing index 1.1 after aging at 85℃ for 1000h; no delamination after 7.8 months of storage at room temperature. Example 4

[0028] This embodiment provides a low-temperature stable, high-thixotropic, UV-thermal dual-curing adhesive and its preparation method, as detailed below: (a) Pretreatment of composite thixotropic agent: 35 kg of ultrapure modified spherical silica (particle size 2 μm, Evonik AEROSIL 812S), 2.5 kg of low haze hydrophobic fumed silica (TOKUSIL 2000HD) and 0.5 kg of KH-560 were stirred in a high-speed mixer at 1500 r / min for 16 min to obtain a pre-dispersed thixotropic agent; (b) Blending of matrix resin: 22 kg of high-transmittance EA (transmittance 93.5%@780nm, Nan Ya NPES-901, epoxy value 0.48±0.02eq / 100g) and 15 kg of PCL-OH (molecular weight 2000, Perrun PCL-2000) were added to a double planetary stirrer and stirred at 80℃ for 30 min to obtain blended resin, and then cooled to 50℃; (c) Composite preparation: Add the pre-dispersed thixotropic agent from step (a) to the blended resin from step (b) and stir at 1200 r / min for 42 min; then add the composite photoinitiator (2.2 kg 1173, 1.0 kg BP), 4.2 kg blocked isocyanate (Bayer Desmodur BL 3175), 0.9 kg KH-560, 0.35 kg 1010 and 0.25 kg UV absorber UV-531 in sequence, continue stirring at 50℃ and 1000 r / min for 30 min, degas under vacuum at -0.09 MPa for 30 min, and cool to room temperature in the dark.

[0029] The obtained product will undergo the following performance tests (radar substrate bonding): Curing: Irradiate with 365nm ultraviolet light (820mW / cm²) for 38s, then heat at 86℃ for 26min; Performance: Radar signal insertion loss 0.18dB; thixotropic index 4.4 at -40℃, thixotropic index 5.5 at 25℃; adhesion strength to FR4 substrate 16.5MPa; shear strength retention rate 91% after aging at 85℃ for 1000h; no delamination after 7.6 months of storage at room temperature. Example 5

[0030] This embodiment provides a low-temperature stable, high-thixotropic, UV-thermal dual-curing adhesive and its preparation method, as detailed below: (a) Pretreatment of composite thixotropic agent: 40 kg of ultrapure modified spherical silica (particle size 2 μm, Evonik AEROSILR812S), 2.5 kg of low haze hydrophobic fumed silica (Tokuyama TOKUSIL 2000HD) and 0.45 kg of KH-560 were stirred in a high-speed mixer at 1500 r / min for 14 min to obtain a pre-dispersed thixotropic agent; (b) Blending of matrix resin: 20 kg of high-transmittance EA (transmittance 93.5%@780nm, Nanya NPES-901, epoxy value 0.48±0.02eq / 100g) and 25 kg of PCL-OH (molecular weight 2200, Daicel, Japan) were added to a double planetary stirrer and stirred at 80℃ for 30 min to obtain blended resin, and then cooled to 50℃; (c) Composite preparation: Add the pre-dispersed thixotropic agent from step (a) to the blended resin from step (b) and stir at 1200 r / min for 35 min; then add the composite photoinitiator (1.5 kg 1173, 0.6 kg BP), 3.8 kg blocked isocyanate (Bayer Desmodur BL 3175), 0.5 kg KH-560, 0.25 kg 1010 and 0.18 kg UV absorber UV-531 in sequence, continue stirring at 50℃ and 1000 r / min for 21 min, degas under vacuum at -0.09 MPa for 30 min, and cool to room temperature in the dark.

[0031] The obtained product will undergo the following performance tests (camera secured with soft adhesive): Curing: Irradiate with 365nm ultraviolet light (780mW / cm²) for 50s, then heat at 82℃ for 28min; Performance: Light transmittance 92.5%@780nm, haze 0.9%; thixotropic index 4.3 at -40℃, thixotropic index 5.2 at 25℃; bonding strength with soft plastic 14.8MPa; yellowing index 1.2 after aging at 85℃×1000h; no delamination after 7.2 months of storage at room temperature.

[0032] Comparative Example 1 This example provides a curing adhesive and its preparation method, which is basically the same as that in Example 1, except that 42 kg of low-haze hydrophobic fumed silica (Tokuyama TOKUSIL 2000HD) was used instead of ultrapure modified spherical silica.

[0033] Performance: Light transmittance 88.3%@780nm, haze 2.1% (cannot meet the optical requirements of cameras); thixotropic index 2.6 at -40℃, excess adhesive after 15min; bonding strength with glass lens 13.5MPa; yellowing index 1.8 after aging at 85℃×1000h.

[0034] Comparative Example 2 This example provides a curing adhesive and its preparation method, which is basically the same as that in Example 2, except that 42 kg of ultrapure modified spherical silica (particle size 3 μm, brand name Shenna SQ-3) was used instead of low-haze hydrophobic fumed silica.

[0035] Performance: Radar signal insertion loss of 0.6dB (unable to meet radar requirements); thixotropic index of 1.9 at -40℃, flowing immediately after application; adhesion strength to aluminum alloy radome of 12.8MPa; sedimentation occurs after 4.5 months of storage.

[0036] Comparative Example 3 This example provides a curing adhesive and its preparation method, which is basically the same as that in Example 1, except that 0.2 kg of ultraviolet absorber UV-531 was not added.

[0037] Performance: Light transmittance 92.6%@780nm, haze 0.9%; yellowing index 2.5 after aging at 85℃×1000h (camera imaging distortion); shear strength retention 78%; bonding strength with glass lens 14.2MPa.

[0038] Comparative Example 4 This example provides a curing adhesive and its preparation method, which is basically the same as that in Example 1, except that 4 kg of fatty amine curing agent (EPIKURE 3370) is used instead of blocked isocyanate.

[0039] Performance: 92.5% transmittance at 780nm, haze 0.8%; thixotropic index 4.0 at -40℃; pre-curing occurs after 1 month of storage at room temperature (viscosity increases by 300%), making it unsuitable for mass production packaging; adhesion strength to CMOS chips 13.9MPa.

[0040] Comparative Example 5 This example provides a curing adhesive and its preparation method, which is basically the same as that in Example 1, except that: an excessive amount of composite thixotropic agent is used: 60 kg of ultrapure modified spherical silica (particle size 2 μm, Evonik AEROSIL R812S) and 3 kg of low-haze hydrophobic fumed silica (Tokuyama TOKUSIL 2000HD).

[0041] Performance: Radar signal insertion loss 0.8dB (severely affects radar performance); transmittance 89.7%@780nm, haze 1.8%; difficult to apply adhesive (cannot be extruded smoothly); thixotropic agent agglomeration occurs after 6 months of storage; adhesion strength to aluminum alloy radome 15.1MPa.

[0042] Comparative Example 6 This example provides a curing adhesive and its preparation method, which is basically the same as that in Example 1, except that: an excess of terminal hydroxyl polycaprolactone was used: 35 kg PCL-OH (molecular weight 2000, Perrun PCL-2000).

[0043] Performance: Light transmittance @780nm 91.5%~92.0%, haze 1.2%~1.5%. Although no serious optical distortion was observed, it no longer meets the core requirements of camera lenses for high light transmittance and low haze. Thixotropy: Thixotropic index is only 3.8~4.0 at -40℃ and 4.8~5.0 at 25℃, indicating a weakened thixotropic effect and reduced anti-flow ability after sizing. Mechanical properties: 13.0~13.8MPa. Cohesive strength is reduced due to excessive flexible chain. In terms of aging stability, the yellowing index reaches 1.6~1.8 after aging at 85℃×1000h, and the shear strength retention rate is 80%~85%. High-temperature oxidation of polyester chains leads to significant performance degradation. Storage stability is poor. Delamination / settling occurs after 4~5 months of storage at room temperature, and the curing shrinkage rate is 2.0%~2.2%. Overall, it cannot meet the long-term use requirements of optical devices.

[0044] Comparative Example 7 This example provides a curing adhesive and its preparation method, which is basically the same as that in Example 1, except that: insufficient terminal hydroxyl polycaprolactone is used: 8 kg PCL-OH (molecular weight 2000, Perrun PCL-2000).

[0045] Performance: Light transmittance at 780nm remained at 92.5%~92.7%, haze was only 0.7%~0.8%, and optical uniformity was good, close to the level of Example 1; thixotropic properties were relatively stable, with a thixotropic index of 4.2~4.3 at -40℃ and 5.1~5.2 at 25℃, and the thixotropic agent network was not significantly affected; the adhesive strength was 14.5~15.0MPa, which was higher than that of Comparative Example 6, but the insufficient flexible chain led to increased brittleness of the adhesive layer, and the adhesive strength decreased by 30% at a low temperature of -40℃, significantly increasing the risk of brittle cracking; the aging performance was better than that of Comparative Example 6, with a yellowing index of 1.3~1.5 after aging at 85℃×1000h, and a shear strength retention rate of 88%~90%, but the rigid adhesive layer was prone to microcracks; the storage stability was good, with no delamination after 6~7 months of storage at room temperature, but the insufficient PCL-OH led to a decrease in photothermal curing crosslinking density, a decrease in curing speed, and insufficient low-temperature toughness, which could not meet the requirements of low-temperature scenarios such as outdoor equipment.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. At the same time, those skilled in the art should understand and implement the above description. Therefore, any equivalent changes or modifications made without departing from the concept disclosed in the present invention should be covered within the scope of protection of the present invention.

Claims

1. A low-temperature stable, high-thixotropic, UV-curable, and heat-curing dual-curing adhesive, characterized in that, The raw material components include the following parts by weight: 15-25 parts of high-transmittance epoxy acrylate; 15-25 parts of hydroxyl-terminated polycaprolactone; 37-58 parts of composite thixotropic agent; 2-4.5 parts of composite photoinitiator; 3-6 parts of blocked isocyanate; 0.5-1.2 parts of silane coupling agent; Antioxidant 0.2~0.5 parts; 0.1 to 0.3 parts of ultraviolet absorber; The composite thixotropic agent is a mixture of ultrapure modified spherical silica and low-haze hydrophobic fumed silica in a mass ratio of 11 to 26:

1.

2. The low-temperature stable, high-thixotropic, UV-thermal dual-curing adhesive according to claim 1, characterized in that: The high-transmittance epoxy acrylate has a transmittance of ≥93% at 780nm and an epoxy value of 0.5~0.6eq / 100g.

3. The low-temperature stable, high-thixotropic, UV-thermal dual-curing adhesive according to claim 1, characterized in that: The number-average molecular weight of the terminal hydroxyl polycaprolactone is 1500~2500.

4. The low-temperature stable, high-thixotropic, UV-thermal dual-curing adhesive according to claim 1, characterized in that: The composite photoinitiator is a mixture of 2-hydroxy-2-methyl-1-phenyl-1-propanone and benzophenone in a mass ratio of 2~3:

1.

5. The low-temperature stable, high-thixotropic, UV-thermal dual-curing adhesive according to claim 1, characterized in that: The blocked isocyanate is an MDI trimer blocked by ε-caprolactam, with a deblocking temperature of 80~100℃ and a yellowing index ≤0.8 after aging at 85℃ for 1000h.

6. The low-temperature stable, high-thixotropic, UV-thermal dual-curing adhesive according to claim 1, characterized in that: The ultrapure modified spherical silica has a particle size of 1~3μm, and the low-haze hydrophobic fumed silica has a specific surface area of ​​200~300m². 2 / g, haze contribution ≤0.5%.

7. A method for preparing the low-temperature stable, high-thixotropic, UV-curable dual-curing adhesive according to any one of claims 1 to 6, characterized in that, Includes the following steps: (a) Pretreatment of composite thixotropic agent: The composite thixotropic agent and the silane coupling agent in the prescribed amount are stirred and mixed to obtain a pre-dispersed thixotropic agent; (b) Blending of matrix resin: The high-transmittance epoxy acrylate and the terminal hydroxyl polycaprolactone are mixed at 75~85°C to obtain a blended resin; (c) Composite preparation: Add the pre-dispersed thixotropic agent to the blended resin of step (b), stir and mix, then add the formulated amount of the composite photoinitiator, blocked isocyanate, antioxidant and ultraviolet absorber, mix and stir, then degas under vacuum and cool in the dark.

8. The application of the low-temperature stable, high-thixotropic, UV-thermal dual-curing adhesive according to any one of claims 1 to 6, characterized in that: Used for encapsulation or bonding of cameras and radar.

9. The application of the low-temperature stable high thixotropic UV-thermal dual-curing adhesive according to claim 8, characterized in that: Used for bonding camera lenses to mounts, fixing camera CMOS chips to substrates, sealing radar radomes, and bonding radar chips to substrates. The application environment temperature is -40~85℃.