Semi-oil and semi-water composite adhesive and preparation method thereof

Abstract

The invention relates to the field of material science, and particularly discloses a semi-oil semi-water composite adhesive which is a single-phase liquid before curing and comprises the following raw materials in parts by weight: polyethylene glycol diglycidyl ether; the solvent is 1, 4-butanediol diglycidyl ether; aliphatic polyurethane acrylate; isobornyl acrylate; camphorquinone; and ethyl-4-dimethylaminobenzoate is used as a raw material. A triaryl sulfonium hexafluoroantimonate mixture; the preparation method comprises the following steps: S1, preparing a homogeneous precursor: mixing raw materials until a clear and transparent single-phase liquid is formed; s2, performing first-stage curing to form a hydrophobic polymer network skeleton; and S3, carrying out second-stage curing to form the hydrophilic polyether network. According to the composition disclosed by the invention, the composition which is a homogeneous liquid before curing is adopted, and a physical interface weak point caused by migration or enrichment of an emulsifier does not exist in a cured polymer system, so that the cohesive strength and long-term hydrolysis-resistant stability of a cured product are improved.

Description

Technical Field

[0001] This application relates to the field of materials science, and more specifically, to a semi-oil, semi-water composite adhesive and its preparation method. Background Technology

[0002] Adhesives, as key basic materials for achieving material bonding and functional integration, play an indispensable role in many industrial production and manufacturing fields. To obtain composite materials with multiple excellent properties, combining hydrophobic and hydrophilic components is an important technological development direction in the adhesive field.

[0003] However, the inherent thermodynamic incompatibility between these two types of chemical components is the core obstacle that must be overcome to achieve their effective composite. To address this issue, one of the most common strategies in existing technologies is to add emulsifiers or surfactants. These amphiphilic additives can disperse the immiscible oil and aqueous phases into a stable emulsion system, thereby obtaining a macroscopically homogeneous liquid precursor. Waterborne polyurethane dispersions and acrylate emulsions are typical products based on this principle.

[0004] While this method is effective in preparing homogeneous liquids, it also introduces new and persistent technical drawbacks. Emulsifiers or surfactants, as non-reactive added small molecules, do not chemically bind to the ultimately cured polymer network. Therefore, during curing and subsequent use, these free small molecules tend to migrate and accumulate, forming microscopic phase interfaces or aggregates within the polymer matrix. These regions constitute physical weak points, easily becoming stress concentration points under external forces, thus reducing the cohesive strength of the cured material. Furthermore, most emulsifiers are inherently hydrophilic; their accumulation within the material creates water-absorbing channels, significantly reducing the material's long-term hydrolytic stability and reliability under humid and hot conditions. Summary of the Invention

[0005] To address the problem that emulsifiers or surfactants commonly added in existing technologies to mix incompatible oil and water components can migrate and form weak points at the interface in the cured product, thereby impairing the cohesive strength and long-term hydrolytic stability of the material, this application provides a semi-oil and semi-water composite adhesive and its preparation method.

[0006] This application provides a semi-oil, semi-water composite adhesive and its preparation method, which adopts the following technical solution: A semi-oil, semi-water composite adhesive, which is a single-phase liquid before curing, and comprises the following raw materials in parts by weight: 30-50 parts of polyethylene glycol diglycidyl ether; 5-15 parts of 1,4-butanediol diglycidyl ether; 30-50 parts of aliphatic polyurethane acrylate; 10-20 parts of isoborneol acrylate; Camphor quinone 0.5-2.0 parts; 1.0-3.0 parts of ethyl-4-dimethylaminobenzoate; 0.5-3.0 parts of a mixture of triarylsulfonium hexafluoroantimonate.

[0007] By adopting the above technical solution, since hydrophilic epoxy components and hydrophobic acrylate components that can form a uniform single-phase liquid before curing are used, and a free radical and cationic photoinitiation system that has independent response to different wavelengths of light is configured, macroscopic phase separation can be suppressed during sequential curing, promoting the formation of a uniform interpenetrating polymer network. The tensile shear strength of the cured product can reach more than 14.0 MPa.

[0008] Preferably, it also contains 0.5-2.0 parts of γ-glycidoxypropyltrimethoxysilane.

[0009] By adopting the above technical solution, since the trimethoxysilane group contained in γ-glycidoxypropyltrimethoxysilane can react with the hydroxyl groups on the surface of the inorganic substrate, and its epoxy group can copolymerize into the polymer network of the adhesive, the interfacial bonding strength between the cured product and the inorganic substrate is improved, and the hydrolytic stability of the bonding interface is improved.

[0010] Preferably, the number-average molecular weight of the polyethylene glycol diglycidyl ether is in the range of 400-800 g / mol.

[0011] By adopting the above technical solution, since the number average molecular weight of polyethylene glycol diglycidyl ether is controlled within the range of 400-800 g / mol, the solubility parameters of polymers in this molecular weight range are compatible with the hydrophobic components in the system. At the same time, the epoxy functional group density and chain segment flexibility are at a specific level. Therefore, under the premise of ensuring that the system forms a stable homogeneous solution before curing, the final cured product can form a network structure with specific crosslinking density and toughness.

[0012] Preferably, the number-average molecular weight of the aliphatic polyurethane acrylate is in the range of 1500-3000 g / mol.

[0013] By adopting the above technical solution, since the number average molecular weight of aliphatic polyurethane acrylate is controlled within the range of 1500-3000 g / mol, the prepolymer in this molecular weight range has a moderate liquid viscosity to facilitate the formation of a homogeneous system, and after curing, it can impart specific segment flexibility and crosslinking density to the hydrophobic network. Therefore, while ensuring the cohesive strength of the cured product, the modulus and toughness of the final product can be synergistically adjusted.

[0014] Preferably, the aliphatic polyurethane acrylate is prepared by reacting hexamethylene diisocyanate and polytetrahydrofuran diol, followed by end-capping with hydroxyethyl acrylate.

[0015] By adopting the above technical solution, since the aliphatic hexamethylene diisocyanate is reacted with flexible polytetrahydrofuran diol, the main chain of the prepolymer prepared does not contain benzene ring structures that are easily degraded by ultraviolet light. At the same time, the flexible polyether segments introduced into its structure can improve the toughness of the final cured product, so that the cured adhesive product has both weather resistance and specific physical toughness.

[0016] Secondly, this application provides a method for preparing a semi-oil, semi-water composite adhesive, using the following technical solution: A preparation process for a semi-oil-semi-water composite adhesive, comprising the following steps: S1. Preparation of homogeneous precursor: Under light-protected conditions, a mixture of polyethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, aliphatic polyurethane acrylate, isoborneol acrylate, camphorquinone, ethyl-4-dimethylaminobenzoate, triarylsulfonium hexafluoroantimonate, and γ-glycidyl etheroxypropyltrimethoxysilane is mixed and stirred at 25-40°C for 15-60 minutes until a clear and transparent single-phase liquid is formed; S2, First stage curing: After applying the single-phase liquid obtained in step S1 to the surface of the substrate, it is irradiated with long-wavelength light with a center wavelength of 450-470nm to initiate free radical polymerization of aliphatic polyurethane acrylate and isoborneol acrylate to form a hydrophobic polymer network skeleton. S3. Second stage curing: The product of step S2 is irradiated with short-wavelength light with a spectral range of 250-400nm to initiate cationic polymerization of the polyethylene glycol diglycidyl ether and 1,4-butanediol diglycidyl ether through photocatalytic acid catalyst to form a hydrophilic polyether network.

[0017] By adopting the above technical solution, and using two independent photoinitiation systems that selectively respond to specific wavelengths of light, and implementing a sequential curing step based on this, namely, first using long-wavelength light to selectively initiate free radical polymerization to form a polymer backbone, and then using short-wavelength light to initiate cationic polymerization within the backbone, the process can obtain a gel-state intermediate that allows for component positioning after the first curing stage, and form a two-phase network structure that is uniformly interpenetrating at the microscale after final curing, thereby avoiding macroscopic phase separation and internal stress concentration caused by synchronous reactions.

[0018] Preferably, in step S1, the stirring speed is 100-300 rpm.

[0019] By adopting the above technical solution, the stirring speed is set in the range of 100-300 rpm. This speed can provide the shear force required for the components to completely dissolve and form a single-phase liquid. At the same time, it avoids the introduction of air bubbles into the liquid due to excessive speed. Therefore, a homogeneous liquid precursor without air bubble defects can be obtained within a specified process time, which provides a prerequisite for subsequent curing to form a final product with a complete structure.

[0020] Preferably, in step S2, the illumination intensity of the long-wavelength light is 100-500 mW / cm². 2 The irradiation time is 5-30 seconds.

[0021] By adopting the above technical solution, since the light intensity and time of the first stage curing are set within a specific range, the energy input is sufficient to polymerize the hydrophobic acrylate component to form a gel network with initial positioning ability. At the same time, the time window avoids the system from directly curing into a hard solid due to over-reaction. Therefore, an intermediate product that allows the substrate to be in a surface-dried gel state can be accurately obtained.

[0022] Preferably, in step S3, the illumination intensity of the short-wavelength light is 50-200 mW / cm². 2 The irradiation time is 60-300 seconds.

[0023] By adopting the above technical solution, since the light intensity and irradiation time of the second stage curing are set within a specific range, the energy input of this setting can ensure that the hydrophilic epoxy component polymerizes to a high conversion rate within the formed hydrophobic network skeleton. Therefore, the overall network structure of the adhesive can be fully cured, thereby ensuring that the final cured product obtains its preset mechanical strength and chemical stability.

[0024] Preferably, after step S3, a post-curing step is also included, in which the sample is kept at a temperature of 25-60°C and protected from light for 1-24 hours.

[0025] By adopting the above technical solution, since the photocatalyst used in step S3 still maintains catalytic activity after the light irradiation stops, and the subsequent mild heating treatment can enhance the mobility of unreacted functional groups in the polymer network, the cationic ring-opening polymerization reaction can continue to a higher conversion rate, thereby further improving the crosslinking density of the cured product and ensuring that the final product reaches its preset mechanical strength and chemical stability.

[0026] In summary, this application has the following beneficial effects: 1. Since this application uses a composition that is a homogeneous liquid before curing, and since the composition formulation does not contain emulsifiers or surfactants, it achieves the effect of improving the cohesive strength and long-term hydrolytic stability of the cured product by eliminating the physical interface weaknesses caused by the migration or enrichment of emulsifiers within the polymer system after curing.

[0027] 2. In this application, a nano-interpenetrating polymer network structure formed by reaction-induced phase separation is preferred. Since two polymer networks with different chemical properties interpenetrate with each other at the molecular scale in this structure, the final cured product can simultaneously possess the chemical resistance and low moisture absorption imparted by the hydrophobic network, as well as the adhesion to polar substrates imparted by the hydrophilic network.

[0028] 3. The method of this application first initiates rapid free radical polymerization by using long wavelength light to form a gel skeleton with preliminary positioning ability. At this time, the hydrophilic network has not yet started to polymerize, thus providing users with a process time window for precise alignment and adjustment of parts before final curing. Attached Figure Description

[0029] Figure 1 This is a flowchart of a semi-oil, semi-water composite adhesive and its preparation method provided in this application. Detailed Implementation

[0030] The present application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0031] Existing technologies for semi-oil and semi-water composite adhesives mostly rely on emulsifiers or surfactants to prepare oil-in-water or water-in-oil emulsion systems. A problem with this approach is that small-molecule additives such as emulsifiers remain at the oil-water interface after curing, creating physical weaknesses that reduce the cohesive strength, water resistance, and long-term bonding reliability of the cured product.

[0032] This technical solution aims to solve the aforementioned technical problems. The specific technical means are as follows: First, all hydrophilic and hydrophobic reactive monomers / oligomers, along with two initiators sensitive to long-wavelength and short-wavelength light respectively, are pre-mixed to prepare a single-phase liquid composition that is emulsifier-free and physically homogeneous and stable.

[0033] Secondly, a step-by-step curing process is employed during the curing process: firstly, long-wavelength light irradiation is used, the energy of which can selectively induce free radical polymerization of the hydrophobic network precursor, thereby forming a hydrophobic polymer network framework with preliminary shape stability throughout the system; subsequently, short-wavelength light irradiation is used, the energy of which is used to induce cationic polymerization of the hydrophilic network precursor. Since the latter polymerization process occurs under the constraint of the former network framework, the reaction-induced phase separation of the system is confined to the nanoscale, ultimately forming a nano-interpenetrating polymer network structure in situ.

[0034] Example of preparation of raw materials and / or intermediates: Preparation Example 1: Preparation of Aliphatic Polyurethane Acrylates Add 1000 g of polytetrahydrofuran diol (1000 g / mol number average molecular weight) and 0.2 g of dibutyltin dilaurate to a 2000 mL four-necked flask equipped with a mechanical stirrer, thermometer, reflux condenser, and nitrogen delivery tube. Heat the system to 75 °C under nitrogen protection and continuous stirring at 150 rpm.

[0035] Subsequently, 336g of hexamethylene diisocyanate was slowly added dropwise through a constant-pressure dropping funnel. The addition process was completed within 60 minutes, and the temperature of the reaction system was maintained below 85°C by adjusting the cooling water flow rate in the reactor jacket. After the addition was complete, the reaction was continued at 80-85°C for 120 minutes.

[0036] Samples were taken from the reaction system, and the content of -NCO groups in the system was determined by di-n-butylamine titration. When the -NCO content reached the range of 4.0-4.3 wt%, the system was cooled to 60 °C.

[0037] Under stirring, 232g of hydroxyethyl acrylate and 0.5g of hydroquinone monomethyl ether polymerization inhibitor were added in one batch. The reaction was continued at 60-65℃ for 180 minutes. During the reaction, samples were taken every 60 minutes and detected by Fourier transform infrared spectroscopy. When the value was at 2270cm... -1 The reaction endpoint is determined when the peak area of ​​the characteristic absorption peak of -NCO at the given point no longer changes significantly.

[0038] The final product, a colorless to pale yellow viscous transparent liquid, is the target product, aliphatic polyurethane acrylate, with a number-average molecular weight of approximately 2500 g / mol as determined by gel permeation chromatography. It is sealed in a brown container and stored at 4°C protected from light for later use.

[0039] According to a first aspect of this application, this application provides a semi-oil, semi-water composite adhesive, which is a single-phase liquid before curing and comprises the following raw materials in parts by weight: 30-50 parts of polyethylene glycol diglycidyl ether; 5-15 parts of 1,4-butanediol diglycidyl ether; 30-50 parts of aliphatic polyurethane acrylate; 10-20 parts of isoborneol acrylate; Camphor quinone 0.5-2.0 parts; 1.0-3.0 parts of ethyl-4-dimethylaminobenzoate; 0.5-3.0 parts of a mixture of triarylsulfonium hexafluoroantimonate.

[0040] It also contains 0.5-2.0 parts of γ-glycidoxypropyltrimethoxysilane.

[0041] The number-average molecular weight range of polyethylene glycol diglycidyl ether is 400-800 g / mol.

[0042] The number-average molecular weight range of aliphatic polyurethane acrylates is 1500-3000 g / mol.

[0043] Aliphatic polyurethane acrylates are prepared by reacting hexamethylene diisocyanate and polytetrahydrofuran diol, followed by end-capping with hydroxyethyl acrylate.

[0044] According to a second aspect of this application, this application provides a preparation process for a semi-oil-semi-water composite adhesive and its preparation method, which adopts the following technical solution and includes the following steps: S1. Preparation of homogeneous precursor: Under light-protected conditions, a mixture of polyethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, aliphatic polyurethane acrylate, isobornyl acrylate, camphorquinone, ethyl-4-dimethylaminobenzoate, triarylsulfonium hexafluoroantimonate, and γ-glycidyl etheroxypropyltrimethoxysilane is mixed and stirred at 25-40°C for 15-60 minutes until a clear and transparent single-phase liquid is formed; in step S1, the stirring speed is 100-300 rpm; S2, First Stage Curing: After applying the single-phase liquid obtained in step S1 to the substrate surface, irradiate it with long-wavelength light with a center wavelength of 450-470nm to initiate free radical polymerization of aliphatic polyurethane acrylate and isoborneol acrylate, forming a hydrophobic polymer network skeleton; in step S2, the light intensity of the long-wavelength light is 100-500mW / cm². 2 The irradiation time is 5-30 seconds.

[0045] S3. Second-stage curing: The product from step S2 is irradiated with short-wavelength light in the spectral range of 250-400 nm to initiate cationic polymerization of polyethylene glycol diglycidyl ether and 1,4-butanediol diglycidyl ether via a photocatalyst, forming a hydrophilic polyether network. In step S3, the light intensity of the short-wavelength light is 50-200 mW / cm². 2 The irradiation time is 60-300 seconds.

[0046] The process after step S3 also includes a post-curing step, in which the sample is kept at a temperature of 25-60°C in the dark for 1-24 hours.

[0047] Example 1 Example 1 of this application provides a semi-oil, semi-water composite adhesive and its preparation method.

[0048] The method includes the following steps: using the aliphatic polyurethane acrylate prepared in Preparation Example 1, the following raw materials are weighed in parts by weight: 40 parts aliphatic polyurethane acrylate, 15 parts isoborneol acrylate, 35 parts polyethylene glycol diglycidyl ether (number average molecular weight 600 g / mol), 10 parts 1,4-butanediol diglycidyl ether, 1.0 part camphorquinone, 2.0 parts ethyl-4-dimethylaminobenzoate, 1.5 parts triarylsulfonium hexafluoroantimonate mixture, and 1.0 part γ-glycidyl etheroxypropyltrimethoxysilane.

[0049] All the above raw materials were placed in a 500mL light-proof reaction vessel and stirred at 200rpm for 30 minutes at 30°C to obtain a clear and transparent single-phase liquid. This single-phase liquid was then coated onto the overlapping area of ​​two glass substrates (25mm × 100mm), with an overlap area of ​​25mm × 12.5mm and a coating thickness of 100µm. Curing was then performed. The first stage of curing used a light intensity of 200mW / cm² with a center wavelength of 460nm. 2 Irradiate with an LED light source for 15 seconds; Second stage curing: After the first stage curing is completed, immediately use an LED light source with a main peak wavelength of 365nm and a light intensity of 100mW / cm². 2 Irradiate the sample with a high-pressure mercury lamp light source for 120 seconds. After the irradiation process is completed, place the bonded sample in a dark place at 25°C for 24 hours.

[0050] Example 2 Example 2 of this application provides a semi-oil, semi-water composite adhesive and its preparation method. The preparation method is basically the same as in Example 1, except that the weight parts of the raw materials are changed to 30 parts aliphatic polyurethane acrylate (same as in Example 1), 10 parts isoborneol acrylate, 50 parts polyethylene glycol diglycidyl ether (number average molecular weight 400 g / mol), and 5 parts 1,4-butanediol diglycidyl ether. The types and amounts of the remaining initiators and additives are the same as in Example 1. A homogeneous and clear single-phase liquid is obtained through the same mixing process. The curing process of the obtained single-phase liquid is exactly the same as in Example 1.

[0051] Example 3 Example 3 of this application provides a semi-oil, semi-water composite adhesive and its preparation method.

[0052] The difference lies in the parameters of the curing process and the weight proportions of the raw materials: Raw materials: Polyethylene glycol diglycidyl ether (number average molecular weight 600 g / mol): 50 parts; 1,4-Butanediol diglycidyl ether: 15 parts; Aliphatic polyurethane acrylate (number average molecular weight 2000 g / mol): 50 parts; Isoborneol acrylate: 20 parts; Camphorquinone: 2.0 parts; Ethyl-4-dimethylaminobenzoate: 3.0 parts; Triarylsulfonium hexafluoroantimonate mixture: 3.0 parts; γ-glycidyl etheroxypropyltrimethoxysilane: 2.0 parts; Differences in preparation process parameters: The first stage of curing uses light intensity of 400 mW / cm². 2 Irradiate with an LED light source for 8 seconds; the second stage of curing uses a light intensity of 150mW / cm². 2 The coating was irradiated with a high-pressure mercury lamp light source for 90 seconds. The remaining coating and post-curing steps were the same as in Example 1.

[0053] Comparative Example 1: Compared to Example 1, the difference is that 5 parts of polyoxyethylene octylphenol ether (OP-10) were added as an emulsifier, and a milky white adhesive emulsion was prepared by high-speed shearing; during curing, a high-pressure mercury lamp surface light source with a main peak wavelength of 365nm was used for a single 300-second irradiation. All other aspects are the same.

[0054] Comparative Example 2: The difference from Example 1 is that, instead of stepwise irradiation during curing, a broadband high-pressure mercury lamp with 365nm and 460nm spectral outputs is used for a single 120-second irradiation. All other aspects remain the same.

[0055] Comparative Example 3: Compared to Example 1, the difference lies in the use of a single network architecture, specifically divided into: Comparative Example 3A: The adhesive component contains only the hydrophilic network precursor, the corresponding cationic photoinitiator and additives from Example 1, and is cured using the corresponding short-wavelength light.

[0056] Comparative Example 3B: The adhesive component contains only the hydrophobic network precursor and the corresponding free radical photoinitiator from Example 1, and is cured using the corresponding long-wavelength light.

[0057] Test Example 1: Evaluation of the appearance and storage stability of adhesive precursors This test case aims to evaluate the appearance of the adhesive precursors prepared in the initial state of preparation and their storage stability under specific conditions for the examples and comparative examples.

[0058] Experimental steps: Take 50 mL of each of the adhesives prepared in Example 1 (E1), Example 2 (E2), Comparative Example 1 (CE1), and Comparative Example 2 (E1), respectively.

[0059] Each sample was placed in a clean, dry 100mL transparent glass sample bottle and sealed.

[0060] Record the macroscopic appearance of each sample in its initial state (i.e., within 1 hour after preparation).

[0061] Place all sealed sample vials in a light-protected environment at 25°C and store for 30 days.

[0062] After the storage period expires, visually observe and record whether each sample shows signs of layering, turbidity, or precipitation.

[0063] Experimental data: Table 1. Evaluation results of the appearance and storage stability of adhesive precursors.

[0064] Test Example 1 evaluated the appearance and storage stability of the adhesive precursors prepared in Examples 1-2 and Comparative Examples 1-2. The results showed that adhesives E1 and E2 prepared in Examples 1 and 2, as well as the adhesive used in Comparative Example 2, all exhibited a homogeneous, clear, and transparent single-phase liquid state in the initial preparation stage, and no stratification or precipitation occurred after standing at 25°C for 30 days. In contrast, adhesive CE1 prepared by physical emulsification in Comparative Example 1 was a milky white and opaque emulsion in its initial state, and precipitation occurred during storage.

[0065] The reason for the above phenomenon is that, in the technical solution provided in this application, by selecting hydrophilic and hydrophobic network precursors with specific solubility parameters, all components can form a thermodynamically stable homogeneous solution before curing. This homogeneous system does not rely on added emulsifiers or surfactants to maintain its physical stability. Therefore, under long-term storage conditions, oil-water phase separation or component sedimentation due to van der Waals forces or gravity will not occur.

[0066] The technical solution in Comparative Example 1 differs from this one. The oil-water emulsion system formed by its physical emulsification method is inherently thermodynamically unstable. The adsorption of emulsifier molecules at the oil-water interface only provides short-term kinetic stability. Over time, droplets will coalesce or undergo Oswald ripening, ultimately leading to macroscopic phase separation and precipitation. This application avoids this physical instability by forming a homogeneous precursor liquid, thus providing a prerequisite for obtaining a uniformly structured solidified product.

[0067] Test Example 2: Evaluation of the process window during a two-step curing process This test case aims to evaluate whether the curing method provided in this application can form an operable intermediate state during the curing process.

[0068] Experimental steps: The adhesive E1 prepared in Example 1 and the adhesive used in Comparative Example 2 (the same as E1) were coated onto a clean glass substrate, with an adhesive layer thickness of 100µm.

[0069] For samples coated with adhesive E1, only the first stage of curing described in Example 1 was performed: using a center wavelength of 460 nm and a light intensity of 200 mW / cm². 2 Irradiate with an LED light source for 15 seconds.

[0070] For the sample coated with the adhesive used in Comparative Example 2, perform the curing steps described therein: using a total light intensity of 300 mW / cm². 2 The sample was irradiated once with a broadband high-pressure mercury lamp. For comparison, the irradiation was stopped after 15 seconds.

[0071] Within 5 seconds after the illumination step of each sample, the surface of the adhesive layer was touched perpendicularly with the end of a clean glass rod using a force of approximately 1 N, and the physical state of the adhesive layer was recorded. At the same time, the other substrate that was bonded was slightly moved, and the ability of the substrate to be moved was recorded.

[0072] Experimental data: Table 2. Evaluation results of the process window during the two-step curing process.

[0073] Test Example 2 evaluated the effect of different curing methods on the curing behavior of the adhesive. As shown in Table 2, the adhesive of Example 1, after being irradiated with a specific wavelength in the first stage, transformed into a surface-dry gel state, at which point the bonded substrate could still be repositioned. In contrast, the broadband light source used in Comparative Example 2 directly cured the adhesive into a hard solid within the same irradiation time, completely losing its adjustability.

[0074] This phenomenon arises from the curing mechanism employed in this application. In Example 1, the 460nm wavelength light used in the first stage of curing only has enough energy to activate the camphorquinone / ethyl-4-dimethylaminobenzoate free radical photoinitiator system in the system. This causes the hydrophobic acrylate component to polymerize, forming a three-dimensional polymer network framework in the entire liquid system, transforming the material from a liquid state to a gel state with initial positioning capabilities. During this stage, the triarylsulfonium hexafluoroantimonate cationic photoinitiator, which is insensitive to long-wavelength light, does not decompose, and the hydrophilic epoxy component does not polymerize, thus preserving a time window for process adjustment.

[0075] In Comparative Example 2, the use of a broadband light source encompassing both long and short wavelengths simultaneously activated both the radical and cationic initiation systems. This resulted in the simultaneous and rapid polymerization of both hydrophobic and hydrophilic networks. The entire system transitioned directly from a liquid state to a highly crosslinked solid state within an extremely short time, without passing through a stable intermediate gel state. Therefore, this method cannot provide a suitable processing time window for precise component alignment.

[0076] Test Example 3: Adhesion Performance Test This test case aims to evaluate the adhesion strength of the cured products of the embodiments and comparative examples to glass substrates.

[0077] Experimental steps: Tensile shear specimens were prepared using the adhesives and curing methods of Examples 1-3 and Comparative Examples 1-3, respectively. The specimen substrate was glass, and the overlap area was 25 mm × 12.5 mm.

[0078] According to the GB / T7124-2008 standard, the prepared samples, which were cured for 24 hours, were placed on a universal testing machine for testing.

[0079] The test environment was set at a temperature of 23±2℃ and a relative humidity of 50±5%.

[0080] Set the tensile loading speed to 5 mm / min until the sample exhibits adhesive failure.

[0081] Record the maximum load at failure and calculate the tensile shear strength. Test 5 specimens in each group and take the average value of the results.

[0082] Experimental data: Table 3. Adhesion performance test results

[0083] The data from Test Example 3 show that the tensile shear strength of the bonded samples obtained after curing in Examples 1, 2, and 3 is all above 14.6 MPa. In contrast, the tensile shear strength of the cured samples in Comparative Examples 1, 2, 3A, and 3B is significantly lower than that of the examples, with the highest value being only 9.3 MPa.

[0084] The technical solution provided in this application involves a curing process that begins with a homogeneous single-phase liquid precursor. In the first stage, under long-wavelength light irradiation, the hydrophobic network polymerizes to form a framework; subsequently, in the second stage, under short-wavelength light irradiation, the hydrophilic network polymerizes in situ within the already formed framework. This reaction sequence suppresses large-scale phase separation during curing, promoting the formation of an interpenetrating structure at the nanoscale between the two phases. This structure lacks stress concentration points introduced by emulsifiers or macroscopic phase interfaces, thus the overall material exhibits high cohesive strength and adhesion strength to the substrate.

[0085] The low strength of Comparative Example 1 is due to the accumulation of residual emulsifier molecules at the two-phase interface after curing, forming a physically weak zone that becomes the starting point for crack propagation under stress. The simultaneous curing method used in Comparative Example 2 causes the two polymerization reactions to occur simultaneously, resulting in rapid and uncontrolled macroscopic phase separation, leading to internal defects and high internal stress, thus reducing the final adhesive performance. The results of Comparative Examples 3A and 3B show that neither a single hydrophilic nor hydrophobic network can independently provide sufficient overall performance, demonstrating the necessity of the synergistic effect of the two networks.

[0086] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A semi-oil, semi-water composite adhesive, characterized in that: Before curing, it is a single-phase liquid and contains the following raw materials in parts by weight: 30-50 parts of polyethylene glycol diglycidyl ether; 5-15 parts of 1,4-butanediol diglycidyl ether; 30-50 parts of aliphatic polyurethane acrylate; 10-20 parts of isoborneol acrylate; Camphor quinone 0.5-2.0 parts; 1.0-3.0 parts of ethyl-4-dimethylaminobenzoate; 0.5-3.0 parts of a mixture of triarylsulfonium hexafluoroantimonate.

2. The semi-oil, semi-water composite adhesive according to claim 1, characterized in that: It also contains 0.5-2.0 parts of γ-glycidoxypropyltrimethoxysilane.

3. The semi-oil, semi-water composite adhesive according to claim 1, characterized in that: The number-average molecular weight range of the polyethylene glycol diglycidyl ether is 400-800 g / mol.

4. The semi-oil, semi-water composite adhesive according to claim 1, characterized in that: The number-average molecular weight of the aliphatic polyurethane acrylate ranges from 1500 to 3000 g / mol.

5. The semi-oil, semi-water composite adhesive according to claim 1, characterized in that: The aliphatic polyurethane acrylate is prepared by reacting hexamethylene diisocyanate and polytetrahydrofuran diol, followed by end-capping with hydroxyethyl acrylate.

6. A preparation process for a semi-oil, semi-water composite adhesive, characterized in that, The method for using a semi-oil, semi-water composite adhesive according to any one of claims 1-5 comprises the following steps: S1. Preparation of homogeneous precursor: Under light-protected conditions, a mixture of polyethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, aliphatic polyurethane acrylate, isoborneol acrylate, camphorquinone, ethyl-4-dimethylaminobenzoate, triarylsulfonium hexafluoroantimonate, and γ-glycidyl etheroxypropyltrimethoxysilane is mixed and stirred at 25-40°C for 15-60 minutes until a clear and transparent single-phase liquid is formed; S2, First stage curing: After applying the single-phase liquid obtained in step S1 to the surface of the substrate, it is irradiated with long-wavelength light with a center wavelength of 450-470nm to initiate free radical polymerization of aliphatic polyurethane acrylate and isoborneol acrylate to form a hydrophobic polymer network skeleton. S3. Second stage curing: The product of step S2 is irradiated with short-wavelength light with a spectral range of 250-400nm to initiate cationic polymerization of the polyethylene glycol diglycidyl ether and 1,4-butanediol diglycidyl ether through photocatalytic acid catalyst to form a hydrophilic polyether network.

7. The preparation process of a semi-oil, semi-water composite adhesive according to claim 6, characterized in that: In step S1, the stirring speed is 100-300 rpm.

8. The preparation process of a semi-oil, semi-water composite adhesive according to claim 6, characterized in that: In step S2, the illumination intensity of the long-wavelength light is 100-500 mW / cm². 2 The irradiation time is 5-30 seconds.

9. The preparation process of a semi-oil, semi-water composite adhesive according to claim 6, characterized in that: In step S3, the illumination intensity of the short-wavelength light is 50-200 mW / cm². 2 The irradiation time is 60-300 seconds.

10. The preparation process of a semi-oil, semi-water composite adhesive according to claim 6, characterized in that: The process after step S3 also includes a post-curing step, in which the sample is kept at a temperature of 25-60°C in the dark for 1-24 hours.

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