Two-component curing filling adhesive with long operation period, low moisture absorption and low hydrogen evolution as well as preparation method and application of two-component curing filling adhesive

Abstract

The invention discloses a double-component curing filling adhesive with long operation period, low moisture absorption and low hydrogen evolution as well as a preparation method and application of the double-component curing filling adhesive. The two-component curing filling adhesive comprises a component A isocyanate phase and a component B latent amine curing agent phase, and is characterized in that the component A isocyanate phase comprises an isocyanate-terminated prepolymer, epoxy resin, hydrophobic fumed silica, silanized nano aluminum oxide and polyether modified siloxane; and the component B latent amine curing agent phase comprises an acylphosphine oxide photoinitiator, a 4, 4 '-diaminodiphenylmethane curing agent microcapsule, a Lewis acid inhibitor and a hydrogen inhibitor. The two-component curing filling adhesive disclosed by the invention has an operation period of 12 hours; the double-component curing filling adhesive is used for bonding optical fibers, the hydrogen evolution amount (24h, 80 DEG C) is 0.15 mu L / g, and the moisture absorption weight gain rate is 0.13%; the double-component curing filling adhesive prepared by the invention can be completely cured within 120 minutes when being heated at 40 DEG C under 365nm ultraviolet radiation.

Description

Technical Field

[0001] This invention belongs to the field of adhesive preparation technology, specifically relating to a two-component curable filler adhesive with long operating time, low moisture absorption and low hydrogen evolution, its preparation method and application. Background Technology

[0002] In fields such as fiber optic communication and fiber optic sensing, the bonding and sealing of optical fibers to devices and between optical fibers is a core process that directly determines the system's transmission stability, environmental adaptability, and lifespan. Existing fiber optic bonding fillers generally suffer from problems such as short working time (mostly less than 30 minutes, making it difficult to meet the needs of batch construction under complex operating conditions), high moisture absorption (easily leading to interface peeling and signal attenuation due to changes in ambient humidity), and significant hydrogen evolution during the curing process (the generated hydrogen gas forms bubbles, damaging the bond integrity and corroding the fiber coating). These defects are particularly problematic in harsh environments such as submarine communication and high-temperature industrial sensing, easily causing system failures. Two-component curing fillers, as core bonding and sealing materials suitable for the harsh operating conditions of submarine optical cables, play an irreplaceable and crucial role in improving the operational reliability of submarine optical cables, extending their service life, and reducing maintenance costs. Summary of the Invention

[0003] This invention proposes a two-component curable filler adhesive with long operating time, low moisture absorption, and low hydrogen evolution, comprising an isocyanate phase (component A) and a latent amine curing agent phase (component B). The isocyanate phase (component A) includes isocyanate-terminated prepolymer, epoxy resin, hydrophobic fumed silica, silanized nano-alumina, and polyether-modified siloxane. The latent amine curing agent phase (component B) includes acylphosphine oxide photoinitiator, 4,4'-diaminodiphenylmethane curing agent microcapsules, Lewis acid inhibitors, and hydrogen inhibitors. It exhibits excellent adhesion and meets the core requirements of submarine optical cables for water-blocking sealing, adaptability to construction, and low hydrogen evolution.

[0004] Optionally, the isocyanate-terminated prepolymer is obtained by polymerizing polyester polyol PCL-1000 and isophorone diisocyanate in a molar ratio of 1:2.

[0005] Optionally, the epoxy resin is one or a combination of E51, BPF-EP, and F-51, preferably BPF-EP or F-51, and more preferably BPF-EP.

[0006] Optionally, the silanized nano-alumina is nano-alumina powder modified with a silane coupling agent.

[0007] Optionally, the acylphosphine oxide photoinitiator is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO).

[0008] Optionally, the Lewis acid inhibitor is triphenylphosphine.

[0009] Optionally, the hydrogen inhibitor is methylbenzotriazole.

[0010] Optionally, in the isocyanate phase of component A, the isocyanate-terminated prepolymer is 100 parts by weight, the epoxy resin is 20-25 parts by weight, the hydrophobic fumed silica is 4-8 parts by weight, the silanized nano-alumina is 10 parts by weight, and the polyether-modified siloxane is 0.3 parts by weight. In the latent amine curing agent phase of component B, the acylphosphine oxide photoinitiator is 3 parts by weight, the 4,4'-diaminodiphenylmethane curing agent microcapsules are 95 parts by weight, the Lewis acid inhibitor is 1 part by weight, and the hydrogen inhibitor is 1 part by weight; preferably, the epoxy resin is 23-25 ​​parts; preferably, the hydrophobic fumed silica is 4-6 parts by weight, more preferably 5-6 parts by weight. Optionally, the mass ratio of the isocyanate phase A to the latent curing agent phase B is 1:(0.1-0.6), preferably 1:(0.2-0.3).

[0011] This invention also provides a method for preparing a two-component curable filler with long operating time, low moisture absorption, and low hydrogen evolution, comprising the following steps: Step 1: Mix isocyanate-terminated prepolymer, epoxy resin, hydrophobic fumed silica, silanized nano-alumina and polyether-modified siloxane according to the weight proportions to obtain component A; Step 2: Mix the acylphosphine oxide photoinitiator, 4,4'-diaminodiphenylmethane curing agent microcapsules, Lewis acid inhibitor and hydrogen inhibitor evenly according to the weight proportions to obtain component B; Step 3: Mix component A and component B in a certain mass ratio to obtain a two-component curing filler with long operating time, low moisture absorption and low hydrogen evolution.

[0012] Optionally, the method for preparing the isocyanate-terminated prepolymer includes the following steps: (1) transferring polyester polyol PCL-1000 into a container and removing water for 2 hours under a certain temperature and vacuum conditions to obtain dehydrated polyester polyol PCL-1000; (2) transferring the dehydrated polyester polyol PCL-1000, isophorone diisocyanate (IPDI), and catalyst dibutyltin dilaurate into a three-necked flask and purging with nitrogen for protection, and reacting at 75°C for 2 hours to obtain the isocyanate-terminated prepolymer.

[0013] Optionally, the two-component curable filler can be cured under 365nm ultraviolet irradiation and heated at 40°C for 120 minutes.

[0014] This invention also provides an application of a two-component curing filler adhesive with long operating time, low moisture absorption, and low hydrogen evolution for use in submarine optical cables, meeting the stringent requirements of submarine optical cables for low hydrogen evolution, low moisture absorption weight gain, and long operating time of two-component adhesives.

[0015] The advantages and beneficial effects of this invention are as follows: (1) The preparation method of the present invention uses fewer raw materials and has a simple synthesis process; (2) The two-component curing filler of the present invention has a working period of 12 hours; (3) The two-component curing filler of the present invention is used to bond optical fibers. The hydrogen evolution amount (24h, 80℃) is 0.15μL / g, and the moisture absorption weight gain rate is 0.13%. (4) The two-component curing filler prepared in this invention can be completely cured within 120 minutes under 365nm ultraviolet irradiation and heating at 40°C.

[0016] Currently, the moisture absorption and weight gain rate of the two-component curing filler used in submarine optical cables is generally 0.5-1.50%, and the hydrogen evolution rate is basically maintained at 0.01-0.03 mL / g. The two-component adhesive prepared in this invention has a significantly reduced moisture absorption and weight gain rate of 80% and a hydrogen evolution rate of 1%. Detailed Implementation

[0017] The present invention will now be described in further detail with reference to the embodiments.

[0018] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0019] In a first aspect, the present invention provides a two-component curable filler adhesive with long operating period, low moisture absorption, and low hydrogen evolution, comprising an isocyanate phase (component A) and a latent amine curing agent phase (component B). The isocyanate phase (component A) comprises isocyanate-terminated prepolymer, epoxy resin, hydrophobic fumed silica, silanized nano-alumina, and polyether-modified siloxane. The latent amine curing agent phase (component B) comprises acylphosphine oxide photoinitiator, 4,4'-diaminodiphenylmethane curing agent microcapsules, Lewis acid inhibitors, and hydrogen inhibitors. It exhibits excellent adhesion and meets the core requirements of submarine optical cables for water-blocking sealing, adaptability to construction, and low hydrogen evolution of the two-component curable filler adhesive.

[0020] In one embodiment, the isocyanate-terminated prepolymer is obtained by polymerizing polyester polyol PCL-1000 and isophorone diisocyanate in a molar ratio of 1:2.

[0021] In one embodiment, the epoxy resin is one or a combination of E51, BPF-EP, and F-51, preferably BPF-EP or F-51, and more preferably BPF-EP.

[0022] In one embodiment, the silanized nano-alumina is nano-alumina powder modified with a silane coupling agent.

[0023] In one embodiment, the acylphosphine oxide photoinitiator is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO).

[0024] In one embodiment, the Lewis acid inhibitor is triphenylphosphine.

[0025] In one embodiment, the hydrogen inhibitor is methylbenzotriazole.

[0026] In one embodiment, in the isocyanate phase of component A, the isocyanate-terminated prepolymer is 100 parts by weight, the epoxy resin is 20-25 parts by weight, the hydrophobic fumed silica is 4-8 parts by weight, the silanized nano-alumina is 10 parts by weight, and the polyether-modified siloxane is 0.3 parts by weight; in the latent amine curing agent phase of component B, the acylphosphine oxide photoinitiator is 3 parts by weight, the 4,4'-diaminodiphenylmethane curing agent microcapsules are 95 parts by weight, the Lewis acid inhibitor is 1 part by weight, and the hydrogen inhibitor is 1 part by weight; preferably, the epoxy resin is 23-25 ​​parts; preferably, the hydrophobic fumed silica is 4-6 parts by weight, more preferably 5-6 parts by weight. In one embodiment, the mass ratio of the isocyanate phase A to the latent curing agent phase B is 1:(0.1-0.6), preferably 1:(0.2-0.3).

[0027] Secondly, the present invention also provides a method for preparing a two-component curable filler with long operating time, low moisture absorption, and low hydrogen evolution, comprising the following steps: Step 1: Mix isocyanate-terminated prepolymer, epoxy resin, hydrophobic fumed silica, silanized nano-alumina and polyether-modified siloxane according to the weight proportions to obtain component A; Step 2: Mix the acylphosphine oxide photoinitiator, 4,4'-diaminodiphenylmethane curing agent microcapsules, Lewis acid inhibitor and hydrogen inhibitor evenly according to the weight proportions to obtain component B; Step 3: Mix component A and component B in a certain mass ratio to obtain a two-component curing filler with long operating time, low moisture absorption and low hydrogen evolution.

[0028] In one embodiment, the method for preparing the isocyanate-terminated prepolymer includes the following steps: (1) transferring polyester polyol PCL-1000 into a container and placing it under a certain temperature and vacuum conditions to remove water for 2 hours to obtain dehydrated polyester polyol PCL-1000; (2) transferring the dehydrated polyester polyol PCL-1000, isophorone diisocyanate (IPDI), and catalyst dibutyltin dilaurate into a three-necked flask and purging with nitrogen gas for protection, and reacting at 75°C for 2 hours to obtain the isocyanate-terminated prepolymer.

[0029] In one embodiment, the two-component curable filler can be cured under 365nm ultraviolet irradiation and heated at 40°C for 120 minutes.

[0030] Thirdly, the present invention also provides an application of a two-component curing filler adhesive with long operating time, low moisture absorption and low hydrogen evolution for use in submarine optical cables, which meets the stringent requirements of submarine optical cables for two-component adhesives in terms of low hydrogen evolution, low moisture absorption weight gain and long operating time.

[0031] The compounds used in the examples were sourced from the following sources: The polyester polyol PCL-1000 is from Shanghai Maclean Biochemical Technology Co., Ltd. (China). The hydrophobic fumed silica TSP-L20 is from Nanjing Tianxing New Materials Co., Ltd. (China). Isophorone diisocyanate is from Shanghai Maclean Biotech Co., Ltd. (China); Dibutyltin dilaurate is from Shanghai Maclean Biotechnology Co., Ltd. (China); Bisphenol F epoxy resin BPF-EP is from Shanghai Maclean Biotech Co., Ltd. (China); 2,4,6-Trimethylbenzoyl-diphenylphosphine oxide (TPO) is from Shanghai Maclean Biochemical Technology Co., Ltd. (China); Triphenylphosphine is sourced from Shanghai Maclean Biochemical Technology Co., Ltd. (China); Methylbenzotriazole is sourced from Shanghai Maclean Biotechnology Co., Ltd. (China). 4,4'-Diaminodiphenylmethane microcapsules were synthesized by Beijing University of Chemical Technology (China). The synthesis method is as follows: First, a certain proportion of M-DDM powder was dispersed in n-hexane solvent. While stirring, a certain amount of Span-85 surfactant was added dropwise, forming a uniform dispersion system. Second, 3% (mass fraction) of the wall material monomer 2,4-toluene diisocyanate (TDI) (relative to the M-DDM powder) was added dropwise to this dispersion system. Under the combined action of surface tension and the surfactant, the TDI monomer was uniformly distributed on the surface of the M-DDM powder particles. At room temperature, the TDI monomer underwent an addition polymerization reaction with the hydroxyl groups on the surface of the M-DDM particles, forming a continuous polymer film on the surface of the M-DDM particles, i.e., the microcapsule wall, in which the M-DDM curing agent was encapsulated. Finally, the microcapsule curing agent was obtained by heating and curing at 40°C. The silanized nano-alumina was prepared by Beijing University of Chemical Technology (China). The synthesis method is as follows: 5 mL of silane coupling agent KH-560 was weighed and added to 100 mL of 95% ethanol. 10 wt% citric acid aqueous solution was added dropwise to adjust the pH value to 3-4. The mixture was allowed to stand at room temperature for 1 h for hydrolysis. Then, 2 g of nano-Al2O3 powder was added to the above hydrolyzed coupling agent solution. The mixture was heated in a water bath at 45 °C and stirred at 600 r / min for 5.5 h. After centrifugation, the supernatant was discarded. An appropriate amount of anhydrous ethanol was added and the mixture was shaken thoroughly. The mixture was ultrasonically washed 1 to 2 times in an ultrasonic cleaner. After filtration using a sintered glass funnel, the mixture was vacuum dried at 60 °C for 24 h to obtain silanized nano-alumina powder. The polyether-modified siloxane was prepared in-house by Beijing University of Chemical Technology (China). The synthesis method is as follows: Octamethylcyclotetrasiloxane (D4) (177.63 g, 0.7510 mol), 1,1,3,3-tetramethyldisiloxane (HMM) (20.17 g, 0.1502 mol), and acid clay (5.93 g, wt%=3%) were added to a 500 mL dry three-necked flask equipped with a thermometer, stirrer, and condenser. The mixture was heated to 70 °C and then heated for 4 h. After removing the catalyst (acid clay) by filtration, a colorless, clear, viscous liquid was obtained. Allyl polyoxyethylene ether and HPDMS (m 烯丙基聚氧乙烯醚 / m HPDMS =2), added to a 500mL dry three-necked flask equipped with a thermometer, stirrer and condenser. Allyl polyoxyethylene ether and HPDMS were heated to 80°C. Platinum-containing cassette catalyst (wt%=0.02%) was added dropwise under stirring. The solution temperature instantly rose to 120°C and bubbles were generated. The solution gradually changed from turbid to clear within 3 minutes. It was refluxed at 110°C for 2 hours to obtain a light yellow clear viscous liquid.

[0032] The testing instruments and conditions used in this embodiment are as follows: Rotational rheometer: The testing machine model is AntonPaarMCR102, and the test method is in accordance with GB / T12007.7-1989; Hydrogen evolution test: gas chromatography, the testing machine model is Shimadzu GC-2014C, and the test method is in accordance with GB / T4946-2008; Moisture absorption and weight gain rate test: The model of the constant temperature and humidity chamber is PK-TH-100, and the test method is in accordance with GB / T41767-2022.

[0033] Examples 1-3 Polyester polyol PCL-1000 was transferred to a container and placed under vacuum at a certain temperature to remove water for 2 hours. The dehydrated polyester polyol PCL-1000 and isophorone diisocyanate (IPDI) were mixed evenly at a molar ratio of 1:2. Based on the total mass of the dehydrated polyester polyol PCL-1000 and isophorone diisocyanate (IPDI), 0.002 wt% of dibutyltin dilaurate catalyst was added, and the liquid was transferred to a three-necked flask. A condenser was connected, and nitrogen was introduced for protection. The reaction was carried out at 75°C for 2 hours to obtain the isocyanate-terminated prepolymer. BPF was then mixed according to the mass fractions of the isocyanate-terminated prepolymer: 24 wt%: 6 wt%: 10 wt%: 0.3 wt%. -EP epoxy resin, hydrophobic fumed silica, silanized nano-alumina, and polyether-modified siloxane were mixed to obtain component A; 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO), 4,4'-diaminodiphenylmethane curing agent microcapsules, Lewis acid inhibitor triphenylphosphine, and hydrogen inhibitor methylbenzotriazole were mixed uniformly at a mass ratio of 3:95:1:1 to obtain component B; In Examples 1-3, components A and B were mixed at mass ratios of 1:0.3, 1:0.1, and 1:0.6 respectively to prepare a liquid two-component curable filler with long operating time, low moisture absorption, and low hydrogen evolution; the two-component curable filler was cured under 365nm ultraviolet irradiation at 40°C for 120 minutes to obtain a cured filler.

[0034] Examples 4-7 Polyester polyol PCL-1000 was transferred to a container and placed under a certain temperature and vacuum condition to remove water for 2 hours. The dehydrated polyester polyol PCL-1000 and isophorone diisocyanate (IPDI) were mixed evenly at a molar ratio of 1:2. Based on the total mass of the dehydrated polyester polyol PCL-1000 and isophorone diisocyanate (IPDI), 0.002 wt% of dibutyltin dilaurate catalyst was added, and the liquid was transferred to a three-necked flask. A condenser was connected, and nitrogen gas was introduced for protection. The reaction was carried out at 75°C for 2 hours to obtain the isocyanate-terminated prepolymer. Examples 4-7 were prepared sequentially according to the mass fraction of the isocyanate-terminated prepolymer (20 wt%, 25 wt%, 24 wt%, 24 wt%): (6 wt%, 6 wt%). Component A is obtained by mixing BPF-EP epoxy resin (4wt%, 8wt%), hydrophobic fumed silica, silanized nano-alumina, and polyether-modified siloxane in a ratio of 10wt% to 0.3wt%. Component B is obtained by mixing photoinitiator 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO), 4,4'-diaminodiphenylmethane curing agent microcapsules, Lewis acid inhibitor triphenylphosphine, and hydrogen inhibitor methylbenzotriazole in a mass ratio of 3:95:1:1. In Examples 4-7, components A and B are mixed in a mass ratio of 1:0.3 to prepare a liquid two-component curable filler with a long operating period, low moisture absorption, and low hydrogen evolution. The two-component curable filler is cured under 365nm ultraviolet irradiation at 40°C for 120 minutes to obtain a cured filler.

[0035] Table 1. Performance of the two-component cured fillers prepared in Examples 1-7 serial number Operation time (h) Hydrogen evolution rate (μL / g) Moisture absorption weight gain rate (%) Example 1 12 0.15 0.13 Example 2 21 0.48 4.56 Example 3 3 10.85 8.74 Example 4 15 0.17 0.18 Example 5 11 0.19 0.21 Example 6 5 0.37 0.56 Example 7 4 0.44 0.07 As can be seen from the data of Examples 1-7 in Table 1, the two-component curing filler prepared in Example 1 of the present invention has the properties of long operating period, low moisture absorption and low hydrogen evolution.

[0036] Compared to Example 1, Example 2 features a change in the ratio of components A and B. The decreased crosslinking density in Example 2 leads to an increased operating time of 21 hours, but the adhesive cannot fully cure, rendering it unusable. Simultaneously, hydrogen evolution increases significantly. This is due to insufficient curing agent in component B, resulting in incomplete curing. Residual moisture and unreacted isocyanate (prepolymer residue) may undergo slow side reactions with residual amine groups, releasing trace amounts of gas (such as CO2 and H2) during long-term use, forming hidden gas evolution and affecting application stability. Insufficient crosslinking density increases the porosity of the filler adhesive, creating more moisture permeation channels, allowing moisture to easily enter the system through capillary action. Unreacted epoxy groups form hydrogen bonds with water molecules, enhancing moisture adsorption. The densification effect of the hydrophobic filler (hydrophobic fumed silica, silanized nano-alumina) relies on the support of the crosslinking network; insufficient crosslinking leads to uneven filler dispersion and localized hydrophilic defects, further increasing the moisture absorption weight gain to 4.56%.

[0037] Compared with Example 1, Example 3 shows a change in the ratio of components A and B. The increased curing agent content in Example 3 reduces the working time to 3 hours. This is because the high concentration of amine groups increases the probability of collision with epoxy groups, significantly increasing the rate of nucleophilic addition reaction, resulting in rapid cross-linking of the adhesive and viscosity exceeding the construction threshold. At the same time, the excess amine groups exceed the inhibition capacity of triphenylphosphine (inhibitor), and the excess amine groups will occupy the adsorption sites of the inhibitor, causing some epoxy groups to be uninhibited and accelerating the reaction initiation. The excessive release of curing agent from the microcapsules and the excessively high local amine concentration further shorten the working time and may even lead to premature curing in some areas due to uneven mixing. Amine groups are the core source of hydrogen evolution side reactions. Excess amine groups have a significantly increased probability of reacting with residual moisture in the system, generating H2. At the same time, excess amine groups may trigger the aminodecomposition side reaction of the isocyanate prepolymer, releasing CO2 (increasing the total amount of gas evolution). The hydrogen inhibitor (methylbenzotriazole) has insufficient adsorption sites. 1 wt% of the hydrogen inhibitor cannot cover the active sites corresponding to the excess amine groups. The excessively high local amine group concentration leads to the uncontrolled side reaction, and the amount of hydrogen evolution rises to 10.85 μL / g. Residual amine groups are highly polar groups that readily form hydrogen bonds with water molecules. The more excess amine groups there are, the higher the density of polar sites, and the stronger the adsorption capacity for moisture. Excessive amine groups lead to uneven cross-linking networks, with local amine group aggregation forming hydrophilic microregions. Moisture can easily penetrate into these regions through capillary action. At the same time, residual amine groups may undergo slow hydrolysis reactions with moisture, further increasing the moisture absorption. The densification effect of the hydrophobic filler is offset. Even if the hydrophobic filler is uniformly dispersed, the excess polar amine groups will still dominate the hydrophilicity of the system. Considering these factors, the moisture absorption rate increases to 8.74%.

[0038] Compared to Example 1, Example 4 shows a decrease in the proportion of epoxy resin in component A, leading to a lower concentration of epoxy groups and a reduced probability of collision with amine groups in component B, thus slowing down the nucleophilic addition reaction rate. Simultaneously, the relative excess of triphenylphosphine (inhibitor) suppresses capacity redundancy in the 20wt% epoxy system, further delaying the reaction initiation, slowing the rate of viscosity increase in the adhesive, and extending the working time to 15 hours. The slight decrease in crosslinking density results in a slight increase in the microporosity of the cured filler adhesive, increasing the number of moisture permeation channels. However, due to the increased relative proportion of hydrophobic fillers, the relative proportions of hydrophobic fumed silica (6wt%) and silanized nano-alumina (10wt%) in component A increase after the epoxy content decreases. Their hydrophobic effect partially offsets the increase in microporosity, preventing a significant increase in moisture absorption. The core of hydrogen evolution depends on the total amount of amines (the amount of component B remains unchanged, so the concentration of amines remains unchanged). The decrease in epoxy content does not affect the number of side reaction sites between amines and metal impurities / moisture. The amount of hydrogen inhibitor (methylbenzotriazole) is sufficient to effectively cover the active sites, block the hydrogen evolution side reaction, and maintain the advantage of low hydrogen evolution.

[0039] Compared with Example 1, Example 5 shows that the epoxy resin content in component A increases to 25 wt%, the working time decreases slightly, but still meets the basic construction requirements; the hydrogen evolution and moisture absorption weight gain remain at low levels; at the same time, compared with Example 1, the increased epoxy content in Example 5 is conducive to increasing the crosslinking density and the tight arrangement of molecular chains, which effectively offsets shrinkage stress.

[0040] Compared to Example 1, Example 6 shows a decrease in the proportion of hydrophobic fumed silica in component A, leading to a moisture absorption weight gain of 0.56%, exceeding the low moisture absorption threshold. This is because the decreased content of hydrophobic fumed silica reduces the density of hydrophobic sites, significantly increasing the probability of hydrogen bonding between water molecules and the system's polar groups (epoxy groups, residual amine groups). Hydrophobic fumed silica forms a three-dimensional network structure through interparticle hydrogen bonds and van der Waals forces, which is the core source of the adhesive's thickening and thixotropic properties. Its decreased content results in an incomplete network structure, increased fluidity, and difficulty in adhering to vertical surfaces or complex crevices during application. The decreased viscosity leads to uneven mixing and insufficient local hydrogen inhibitor concentration, potentially causing trace local hydrogen evolution peaks. Simultaneously, decreased density may lead to increased residual moisture, causing latent gas evolution during long-term use. The operating time also decreases significantly due to the increased fluidity of the adhesive.

[0041] Compared to Example 1, Example 7 shows an increased proportion of hydrophobic fumed silica in component A, which leads to a decrease in the moisture absorption weight gain rate to 0.07%. Due to particle agglomeration, the thixotropic network becomes too rigid, resulting in loss of fluidity of the adhesive and difficulty in uniform dispersion during mixing (e.g., the microcapsule curing agent in component B cannot be evenly distributed). In some cases, localized areas may not be mixed and may even gel, compressing the actual construction window and reducing the operating time. Excessive agglomeration leads to uneven mixing of the adhesive, insufficient concentration of local hydrogen inhibitors and curing agents, and may result in trace amounts of localized large amounts of hydrogen evolution. At the same time, agglomerates hinder molecular chain movement, which may lead to incompletely cured adhesives that lose their practical value, resulting in problems such as gelation, agglomeration sedimentation, and filling defects.

[0042] In summary, this invention proposes a two-component curable filler with long operating time, low moisture absorption, and low hydrogen evolution, as well as its preparation method. In particular, the two-component curable filler of Example 1 has a long operating time (12h), a low amount of hydrogen evolution (0.15μL / g), and a low moisture absorption weight gain rate (0.13%), which meets the stringent requirements of submarine optical cables for two-component curable fillers.

Claims

1. A two-component curable filler with long operating time, low moisture absorption, and low hydrogen evolution, comprising component A (isocyanate phase) and component B (latent amine curing agent phase), characterized in that, The isocyanate phase of component A includes isocyanate-terminated prepolymer, epoxy resin, hydrophobic fumed silica, silanized nano-alumina, and polyether-modified siloxane; the latent amine curing agent phase of component B includes acylphosphine oxide photoinitiators, 4,4'-diaminodiphenylmethane curing agent microcapsules, Lewis acid inhibitors, and hydrogen inhibitors.

2. The two-component curable filler adhesive as described in claim 1, characterized in that, The isocyanate-terminated prepolymer is obtained by polymerizing polyester polyol PCL-1000 and isophorone diisocyanate in a molar ratio of 1:

2.

3. The two-component curing filler as described in claim 1 or 2, characterized in that, The epoxy resin is one or a combination of E51, BPF-EP, and F-51; and / or, the silanized nano-alumina is nano-alumina powder modified with a silane coupling agent.

4. The two-component curing filler as described in claim 1 or 2, characterized in that, The acylphosphine oxide photoinitiator is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO); and / or, the Lewis acid inhibitor is triphenylphosphine; and / or, the hydrogen inhibitor is methylbenzotriazole.

5. The two-component curable filler as described in claim 1, characterized in that, In component A, the isocyanate phase, the isocyanate-terminated prepolymer is 100 parts by weight, the epoxy resin is 20-25 parts by weight, the hydrophobic fumed silica is 4-8 parts by weight, the silanized nano-alumina is 10 parts by weight, and the polyether-modified siloxane is 0.3 parts by weight; in component B, the latent amine curing agent phase, the acylphosphine oxide photoinitiator is 3 parts by weight, the 4,4'-diaminodiphenylmethane curing agent microcapsules are 95 parts by weight, the Lewis acid inhibitor is 1 part by weight, and the hydrogen inhibitor is 1 part by weight.

6. The two-component curing filler as described in claim 1 or 5, characterized in that, The mass ratio of component A (isocyanate phase) to component B (latent curing agent phase) is 1:(0.1-0.6).

7. A method for preparing a two-component curable filler as described in any one of claims 1-6, characterized in that, Includes the following steps: Step 1: Mix isocyanate-terminated prepolymer, epoxy resin, hydrophobic fumed silica, silanized nano-alumina and polyether-modified siloxane according to the weight proportions to obtain component A; Step 2: Mix the acylphosphine oxide photoinitiator, 4,4'-diaminodiphenylmethane curing agent microcapsules, Lewis acid inhibitor and hydrogen inhibitor evenly according to the weight proportions to obtain component B; Step 3: Mix component A and component B in a certain mass ratio to obtain a two-component curing filler with long operating time, low moisture absorption and low hydrogen evolution.

8. The method for preparing the two-component curable filler as described in claim 7, characterized in that, The method for preparing the isocyanate-terminated prepolymer includes the following steps: (1) transferring polyester polyol PCL-1000 into a container and removing water for 2 hours under a certain temperature and vacuum conditions to obtain dehydrated polyester polyol PCL-1000; (2) transferring the dehydrated polyester polyol PCL-1000, isophorone diisocyanate (IPDI), and catalyst dibutyltin dilaurate into a three-necked flask and purging with nitrogen for protection, and reacting at 75°C for 2 hours to obtain the isocyanate-terminated prepolymer.

9. The two-component curable filler as described in claim 1, characterized in that, It can be cured by heating at 40°C for 120 minutes under 365nm ultraviolet light irradiation.

10. An application of the two-component curing filler as described in any one of claims 1-6 and 9, characterized in that, Used for submarine optical cables.