Bi-component polyurethane foam based on microencapsulation catalyst and preparation method of bi-component polyurethane foam

Abstract

The invention relates to the technical field of polystyrene foam, in particular to bi-component polyurethane polystyrene foam based on a microencapsulation catalyst and a preparation method of the bi-component polyurethane polystyrene foam. The component A comprises polyether polyol, isocyanate and a modified nano composite system; the component B comprises polyether triol, a foaming agent and a microencapsulation catalyst, and the microencapsulation catalyst is dibutyltin dilaurate coated with a polyurea shell layer; a microencapsulation catalyst is introduced into the component B through a low-speed dispersion process before mixing, and a polyurea shell layer is broken through mechanical shear force during mixing to release dibutyltin dilaurate. The microencapsulation catalyst is broken during sizing, compared with a traditional catalytic system, the curing time is greatly shortened, silane coupling agent modified nano silicon dioxide and carbon nano tubes are introduced to synergistically enhance the filler, and the mechanical strength and aging resistance of the polystyrene foam are enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of foaming adhesives, in particular to a two-component polyurethane foaming adhesive based on a microencapsulated catalyst and a preparation method thereof. Background Art

[0002] Polyurethane foam is an adhesive containing carbamate (-NHCOO-) or isocyanate (-NCO) groups in its molecular chain. It is produced by reacting isocyanates with hydroxyl-containing compounds such as polyesters, polyethers, castor oil, or other polyols. It offers excellent performance, including strong molecular designability, a wide range of physical properties, and a broad range of adhesive applications. It is a key synthetic adhesive and is commonly used in the automotive, building decoration, and electrical appliance industries, primarily for filling, bonding, sealing, and sound and heat insulation applications.

[0003] Two-component polyurethane foam is the most diverse, widely used, and versatile polyurethane foam. Its two components are packaged separately, making it easy to store and offering adjustable properties. It boasts high bond strength, a wide range of applications, and excellent weather resistance, demonstrating unique advantages across its diverse applications.

[0004] In the prior art, catalysts are key components for controlling the foaming reaction, directly affecting the foaming rate, pore structure, and final product performance. Under the current development situation, the mainstream method is to add the catalyst directly to the components, which is simple in process, low in cost, and can provide high catalytic activity. This method is mature and reliable and suitable for large-scale production. However, this method is prone to leakage of active ingredients during storage, and slowly reacts with the polyols or foaming agents in the components, resulting in increased viscosity, gelation, or failure. To solve the storage problem, some technologies use heat-sensitive or moisture-sensitive latent catalysts, which are activated under heating or humid conditions. However, they are extremely dependent on external conditions, resulting in uneven release during actual mixing, causing inaccurate initiation of the foaming reaction and uneven pore structure, affecting product consistency.

[0005] The information disclosed in this background technology section is only intended to deepen the understanding of the overall background technology of the present invention and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art known to those skilled in the art. Summary of the Invention

[0006] The first object of the present invention is to provide a two-component polyurethane foam based on a microencapsulated catalyst to solve the contradiction in controlling the activity of the catalyst in the storage and mixing stages of the two-component polyurethane foam, that is, how to achieve precise triggering and release of the catalyst during mixing while ensuring storage stability, so as to avoid component failure or uncontrollable reaction initiation caused by premature activation of the catalyst.

[0007] The above technical objectives of the present invention are achieved through the following technical solutions:

[0008] A two-component polyurethane foam based on a microencapsulated catalyst, which is prepared by mixing components A and B;

[0009] Component A includes polyether polyol, isocyanate and modified nanocomposite system; polyether polyol and isocyanate undergo prepolymerization reaction to form a prepolymer with terminal -NCO groups, which lays the foundation for the flexibility-rigidity balance of the polymer skeleton;

[0010] Component B includes polyether triol, foaming agent and microencapsulated catalyst. The microencapsulated catalyst is dibutyltin dilaurate coated with a polyurea shell. The polyether triol provides an active hydrogen source for the reaction, and the microencapsulated catalyst uses a polyurea shell to physically isolate the highly active tin catalyst.

[0011] The microencapsulated catalyst is introduced into component B through a low-speed dispersion process before mixing. During mixing, the polyurea shell is broken by mechanical shear force to release dibutyltin dilaurate to activate the reaction.

[0012] The polyurea shell in this invention completely blocks the catalyst activity before mixing, achieving an extremely long operating time. Shear forces at the moment of mixing trigger rupture, allowing explosive catalyst release to drive rapid crosslinking of -NCO / -OH groups, resolving the historical conflict between storage stability and instantaneous cure. The nanocomposite system is uniformly dispersed in the prepolymer, providing a fully reinforced network for the foam.

[0013] Preferably, the modified nanocomposite system is composed of silane-coupling agent-modified nanosilica and carbon nanotubes in a mass ratio of 2.5-3.5:1. The silane-coupling agent-modified nanosilica and carbon nanotubes synergistically reinforce the filler. Aminosilane is grafted onto the surface of the nanosilica, reacting with isocyanate groups to form chemical bonds, enhancing interfacial bonding. The carbon nanotubes adsorb polyurethane molecular chains through π-π interactions, forming a three-dimensional network structure that enhances mechanical strength and toughness, addressing the poor aging resistance and susceptibility of polyurethane foam to debonding.

[0014] The modified nanocomposite system is added after the prepolymerization reaction is completed, and the SiO2 / CNT is evenly distributed through ultrasonic dispersion.

[0015] Silane coupling agent-modified nanosilica is obtained by soaking and modifying nanosilica in a 1% aminosilane coupling agent-ethanol solution. Specifically, KH550 aminosilane is hydrolyzed to generate Si-OH, which condenses with the SiO2 surface to form Si-O-Si bonds, improving interfacial adhesion and inhibiting foam shrinkage and cracking. Residual amino groups are oriented outward and react with polyurethane-NCO to form a chemical bond between the filler and the matrix. The carbon nanotubes are multi-walled carbon nanotubes with a diameter of 10-20nm. Their aspect ratio forms a three-dimensional network that transfers stress. The 2.5-3.5:1 mass ratio precisely balances the interface reinforcement of SiO2 with the skeletal support of the carbon nanotubes, preventing agglomeration or performance imbalance.

[0016] Component A preferably also includes a dehydrating agent to precisely remove trace amounts of water adsorbed by the polyether polyol / nanoparticles, preventing the side reaction of water with isocyanate to produce CO2 and ensuring strength. Component A comprises, by weight, 30-50 parts polyether polyol, 50-60 parts isocyanate, 0.5-1 part silane coupling agent-modified nanosilica, 0.2-0.5 part carbon nanotubes, and 3-4 parts dehydrating agent.

[0017] Preferably, the polyether polyol is polypropylene glycol with Mn=2000, whose linear chain segments can provide sufficient flexibility to avoid brittleness caused by excessive cross-linking of the prepolymer; after reacting with 50-60 parts of isocyanate, the NCO content of the prepolymer is stabilized at 12-14%, ensuring that the bubble nucleation rate is synchronized with the chain growth rate during foaming.

[0018] The preferred isocyanate is diphenylmethane diisocyanate (MDI) with an NCO content of 30-32%. This ensures that the NCO content of the prepolymer remains stable at 12-14% during reaction with the polyether polyol, preventing gel runaway or insufficient curing due to an overly rapid reaction. The well-organized hard segment microdomains formed by the reaction of MDI and polyether polyol serve as a template for bubble nucleation, maintaining a stable average cell diameter of 100-150 μm. This uniform cell distribution significantly improves sound and thermal insulation performance.

[0019] Preferably, component B further comprises a foam stabilizer and a filler. Calculated by weight, component B comprises:

[0020] The polyether triol comprises 40-60 parts polyether triol, 8-12 parts blowing agent, 0.5-1 part microencapsulated catalyst, 0.5-1 part foam stabilizer, and 20-40 parts filler. The polyether triol provides ample hydroxyl active sites, reacting with the MDI prepolymer in component A to form a three-dimensional crosslinked network. Its branched structure significantly increases the crosslink density and mechanical strength of the final product while maintaining appropriate flexibility. The addition of 0.5-1 part microencapsulated catalyst ensures instantaneous catalyst release during mixing, shortening foaming time to 10-20 seconds while preventing excess catalyst residue from causing excessive crosslinking later.

[0021] Preferably, the foaming agent is trans-1-chloro-3,3,3-trifluoropropene, which can be rapidly vaporized at room temperature and provide uniform physical expansion power for polyurethane foaming.

[0022] Preferably, the foam stabilizer is an organosilicon foam stabilizer, preferably silicone oil. The silicone oil forms a surface protective layer in component B, preventing water penetration and reducing the viscosity growth rate during storage.

[0023] As a preferred filler, inert fillers such as calcium carbonate or talc can also be selected as functional fillers such as alumina, aluminum hydroxide, glass fiber, etc. By adjusting the filler particle size, the density of the foam can be controlled to meet different load-bearing requirements.

[0024] Preferably, the mass ratio of component A to component B is 0.8-1.2:1.

[0025] Preferably, the shear rate during the low-speed dispersion process is ≤500 rpm. This design ensures the integrity of the microcapsules during production and significantly reduces the risk of quality fluctuations during application. In the present invention, when the shear stress reaches 200±20 Pa, the polyurea shell breaks, releasing the DBTDL catalyst. During production, the shear stress during the dispersion process is controlled to <50 Pa, ensuring the integrity of the microcapsules.

[0026] Preferably, the microencapsulated catalyst is prepared by interfacial polymerization, comprising:

[0027] S1 dissolves dibutyltin dilaurate and polyisocyanate in a hydrophobic solvent to form an oil phase;

[0028] S2 adds the oil phase to the water phase containing the emulsifier for emulsification;

[0029] S3: adding a polyamine aqueous solution to the emulsion, polycondensing at the oil-water interface to form a polyurea shell layer, which covers the dibutyltin dilaurate droplets;

[0030] S4: centrifuging, washing, and drying the reaction solution to obtain a microencapsulated catalyst.

[0031] Preferably, the microencapsulated catalyst is prepared by the following preparation method:

[0032] S1: Dissolve dibutyltin dilaurate DBTDL and polyisocyanate monomer in ethyl acetate solvent in a certain proportion at room temperature in the dark, and stir until completely transparent to form an oil phase;

[0033] Preferably, the polyisocyanate monomer is HDI trimer, the mass ratio of DBTDL to HDI trimer is 1:1-1:2, 10% excess HDI can compensate for the hydrolysis loss of -NCO during the emulsification process, ensure complete interfacial polymerization, and the stirring speed is 300-500 rpm for ≥30 min to ensure the formation of a uniform oil phase.

[0034] S2: dissolving an emulsifier, Span 80, in deionized water at a concentration of 1-5 wt %, and adjusting the pH to a weakly alkaline state with NaOH or triethylamine to form an aqueous phase; slowly adding the oil phase to the aqueous phase, and emulsifying the mixture in a high-speed homogenizer at a speed of 10,000-15,000 rpm to form a stable emulsion;

[0035] The reason for adjusting the pH to a weak alkaline state is that if the pH is too low, SDS will easily form an acidic precipitate, and if the pH is too high, it will easily cause excessive hydrolysis of isocyanate. In the present invention, the pH is controlled at 8-9 to moderate the activity of the polyamine in the subsequent interfacial polymerization and avoid excessive reaction leading to shell defects.

[0036] S3: slowly add the polyamine aqueous solution to the emulsion, and stir the reaction in a constant temperature water bath to obtain a reaction solution, so that the polyisocyanate and the polyamine undergo a condensation reaction at the oil-water interface to form a polyurea shell layer, which covers the DBTDL droplets;

[0037] Preferably, the polyamine is ethylenediamine / diethylenetriamine, and the concentration is 5-10 wt % of the aqueous phase. The polyamine is added dropwise and stirred at 40-50° C. and 300-400 rpm for 2-3 hours.

[0038] S4: centrifuging the reaction solution, washing with deionized water and ethanol alternately, and drying under vacuum at 50-60° C. for 12-24 hours to obtain DBTDL powder coated with polyurea microcapsules, i.e., microencapsulated catalyst.

[0039] The second object of the present invention is to provide a method for preparing a two-component polyurethane foam based on a microencapsulated catalyst. By adding microencapsulated dibutyltin dilaurate as a catalyst, the microencapsulated catalyst breaks during sizing, and the curing time is greatly shortened compared to traditional catalytic systems. In addition, the introduction of silane coupling agent-modified nano-silica and carbon nanotubes synergistically reinforces the filler, thereby enhancing the mechanical strength and aging resistance of the foam.

[0040] The above technical objectives of the present invention are achieved through the following technical solutions:

[0041] A method for preparing a two-component polyurethane foam based on a microencapsulated catalyst comprises:

[0042] (1) Weigh each component according to the proportion;

[0043] (2) Preparation of component A: reacting polyether polyol with isocyanate to form a prepolymer, controlling the NCO content to 12-14%; adding the modified nanocomposite system and then dehydrating; the polyether polyol and isocyanate react under the protection of a dehydrating agent, and the nanofiller is directionally dispersed in the prepolymer in an ultrasonic field to increase the closed cell rate of the foam;

[0044] (3) Preparation of component B: The polyether triol and filler are ball-milled and mixed, and the microencapsulated catalyst, foaming agent, and foam stabilizer are added at a low speed at a shear rate of ≤500 rpm. The polyether triol and filler are sealed and stored after vacuum degassing. The polyether triol and filler are dispersed at a microscopic level by ball milling to eliminate local stress weaknesses. The microencapsulated catalyst is mixed in without loss under low-speed stirring. Stirring at ≤500 rpm ensures that the microcapsules withstand subcritical shear force until they encounter supercritical destructive force during construction, and maintains zero catalyst leakage from production to construction.

[0045] (4) Component A and component B are mixed to obtain polyurethane foam.

[0046] Preferably, in step (2), the polyether polyol and isocyanate are reacted at 70-90° C. for 1.5-2.5 hours, and the NCO content is controlled at 12-14%. The modified nanocomposite system is added, ultrasonically treated for 30-40 minutes, and vacuum dehydrated to a moisture content of <0.05%.

[0047] Preferably, in step (3), the polyether triol and filler are mixed and ball milled for 2-3 hours, and then other components are added and stirred at a low speed to avoid capsule rupture.

[0048] Preferably, the ratio of component A to component B is 0.8-1.2:1.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] (1) The present invention achieves intelligent control of catalyst activity by encapsulating a highly active catalyst in a polyurea shell. Before mixing, the polyurea shell completely isolates the catalyst from contact with the reaction system, ensuring that the material has an extremely long operability time and meeting the needs of complex construction scenarios. At the moment of mixing, mechanical shear force triggers the controlled rupture of the shell, and the catalyst is instantly released and activates the reaction, shortening the curing speed to 5-8 minutes, which is significantly shorter than the traditional catalytic system and avoids pre-curing during the storage period.

[0051] (2) The present invention significantly improves the mechanical properties and durability of the foam through the synergistic effect between the components. The prepolymer network formed by polyether polyol and isocyanate provides the basic skeleton for the material, while the introduction of the modified nanocomposite system constructs a multi-scale reinforced structure. The uniform dispersion of nanomaterials in the matrix forms a three-dimensional support network, which enables the foam to achieve efficient stress transmission and dispersion when subjected to external forces. This optimization of the microstructure enables the material to exhibit excellent compressive and tear resistance on a macro scale, while maintaining good elastic recovery properties. DETAILED DESCRIPTION

[0052] To further illustrate the technical means and effectiveness of the present invention in achieving its intended objectives, a two-component polyurethane foam based on a microencapsulated catalyst and its preparation method, as well as its specific embodiments, features, and effectiveness, are described below. It should be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention.

[0053] The raw materials or reagents used in the Examples of the present invention and / or the Comparative Examples are all purchased from mainstream manufacturers in the market. If the manufacturer is not specified or the concentration is not specified, they are all analytically pure raw materials or reagents that can be routinely obtained. As long as they can play the expected role, there are no special restrictions. The instruments and equipment used in this embodiment are all purchased from major manufacturers in the market. As long as they can play the expected role, there are no special restrictions. If specific techniques or conditions are not specified in this embodiment, they are carried out according to the techniques or conditions described in the literature in this area or according to the product specifications.

[0054] The sources of raw materials used in this specific embodiment are as follows:

[0055] polyether polyols PPG2000, Shell Chemicals Isocyanates Shandong Xuchen Chemical Technology Co., Ltd. Nanosilica Sanming Fengrun Chemical Co., Ltd. carbon nanotubes Jiangsu Tiannai Technology Co., Ltd. Dehydrating agent BF-5 Meizhou Fuxi Chemical Co., Ltd. Polyether triol Zibo Dexin Federal Chemical Industry Co., Ltd. foaming agent Shanghai Yuji Saifu Technology Co., Ltd. DBTDL Guangdong Wengjiang Chemical Reagent Co., Ltd. Ethyl acetate Jinan Century Tongda Chemical Co., Ltd. Span 80 Jiangsu Maoheng Chemical Co., Ltd. Ethylenediamine Changzhou Shanfeng Chemical Co., Ltd. silicone oil WACKER calcium carbonate Shanghai Calcium Carbonate Factory Co., Ltd. KH550 Shandong Hengyu New Materials Co., Ltd.

[0056] Example 1

[0057] A two-component polyurethane foam based on a microencapsulated catalyst is prepared by mixing component A and component B; the mass ratio of component A to component B is 1:1;

[0058] Component A includes polyether polyol, isocyanate and modified nanocomposite system; polyether polyol and isocyanate undergo prepolymerization reaction to form a prepolymer with terminal -NCO groups, which lays the foundation for the flexibility-rigidity balance of the polymer skeleton;

[0059] Component B includes polyether triol, foaming agent and microencapsulated catalyst. The microencapsulated catalyst is dibutyltin dilaurate coated with a polyurea shell. The polyether triol provides an active hydrogen source for the reaction, and the microencapsulated catalyst uses a polyurea shell to physically isolate the highly active tin catalyst.

[0060] The microencapsulated catalyst is introduced into component B through a low-speed dispersion process of ≤500 rpm before mixing. The polyurea shell is broken by mechanical shear force during mixing to release dibutyltin dilaurate to activate the reaction.

[0061] Component A also includes a dehydrating agent. Calculated by weight, component A includes: 40 parts of polyether polyol, 55 parts of isocyanate, 0.9 parts of silane coupling agent-modified nano-silica, 0.3 parts of carbon nanotubes, and 3.8 parts of dehydrating agent.

[0062] The polyether polyol is PPG2000. The isocyanate is MDI. The modified nanocomposite system is composed of nano-silica modified with KH550-ethanol solution and carbon nanotubes in a mass ratio of 3:1.

[0063] Component B also includes a foam stabilizer and a filler. Calculated by weight, component B includes: 55 parts of polyether triol, 10 parts of foaming agent, 0.8 parts of microencapsulated catalyst, 0.8 parts of foam stabilizer, and 33.4 parts of filler.

[0064] The foaming agent is HCFO-1233zd. The foam stabilizer is silicone oil L-6900. The filler is calcium carbonate.

[0065] The microencapsulated catalyst is prepared by interfacial polymerization, which includes:

[0066] S1: Dissolve dibutyltin dilaurate (DBTDL) and HDI trimer in ethyl acetate at a mass ratio of 1:1.05 at room temperature in the dark, and stir until completely transparent to form an oil phase.

[0067] S2: 4 wt% of the emulsifier Span 80 was dissolved in deionized water and the pH was adjusted to 8 with NaOH to form an aqueous phase. The oil phase was slowly added to the aqueous phase and emulsified in a high-speed homogenizer (15,000 rpm) for 10 minutes to form a stable emulsion.

[0068] S3: Slowly add an aqueous solution of ethylenediamine to the emulsion, and stir the mixture at 300 rpm in a constant temperature water bath at 50°C to obtain a reaction solution, so that the polyisocyanate and the polyamine undergo a condensation reaction at the oil-water interface to form a polyurea shell layer that covers the DBTDL droplets;

[0069] S4: The reaction solution is centrifuged, washed alternately with deionized water and ethanol three times, and dried under vacuum at 60° C. for 24 h to obtain DBTDL powder coated with polyurea microcapsules, i.e., microencapsulated catalyst.

[0070] A method for preparing a two-component polyurethane foam based on a microencapsulated catalyst comprises:

[0071] (1) Weigh each component according to the proportion;

[0072] (2) Preparation of component A: reacting polyether polyol with isocyanate at 80°C for 2 hours to generate a prepolymer, controlling the NCO content to 13%; adding the modified nanocomposite system, ultrasonically treating for 40 minutes, and then vacuum dehydrating to a moisture content of <0.05%;

[0073] (3) Preparation of component B: The polyether triol and filler were ball-milled for 3 hours, and the microencapsulated catalyst, foaming agent, and foam stabilizer were added at a shear rate of ≤500 rpm. After vacuum degassing, the mixture was sealed and stored.

[0074] (4) Component A and component B are mixed in a mass ratio of 1:1 to obtain polyurethane foam.

[0075] Example 2

[0076] A two-component polyurethane foam based on a microencapsulated catalyst is prepared by mixing component A and component B; the mass ratio of component A to component B is 1:1;

[0077] Component A includes polyether polyol, isocyanate and modified nanocomposite system; polyether polyol and isocyanate undergo prepolymerization reaction to form a prepolymer with terminal -NCO groups, which lays the foundation for the flexibility-rigidity balance of the polymer skeleton;

[0078] Component B includes polyether triol, foaming agent and microencapsulated catalyst. The microencapsulated catalyst is dibutyltin dilaurate coated with a polyurea shell. The polyether triol provides an active hydrogen source for the reaction, and the microencapsulated catalyst uses a polyurea shell to physically isolate the highly active tin catalyst.

[0079] The microencapsulated catalyst is introduced into component B through a low-speed dispersion process of ≤500 rpm before mixing. The polyurea shell is broken by mechanical shear force during mixing to release dibutyltin dilaurate to activate the reaction.

[0080] Component A also includes a dehydrating agent. Calculated by weight, component A includes: 41 parts of polyether polyol, 54.8 parts of isocyanate, 0.9 parts of silane coupling agent-modified nano-silica, 0.3 parts of carbon nanotubes, and 3 parts of dehydrating agent.

[0081] The polyether polyol is PPG2000. The isocyanate is MDI. The modified nanocomposite system is composed of nano-silica modified with KH550-ethanol solution and carbon nanotubes in a mass ratio of 3:1.

[0082] Component B also includes a foam stabilizer and a filler. Calculated by weight, component B includes: 55 parts of polyether triol, 8 parts of foaming agent, 0.8 parts of microencapsulated catalyst, 0.8 parts of foam stabilizer, and 35.4 parts of filler.

[0083] The foaming agent is HCFO-1233zd. The foam stabilizer is silicone oil L-6900. The filler is calcium carbonate.

[0084] The microencapsulated catalyst is prepared by interfacial polymerization, which includes:

[0085] S1: Dissolve dibutyltin dilaurate (DBTDL) and HDI trimer in ethyl acetate at a mass ratio of 1:1.05 at room temperature in the dark, and stir until completely transparent to form an oil phase.

[0086] S2: Dissolve 5 wt% of emulsifier Span 80 in deionized water and adjust the pH to 8 with NaOH to form an aqueous phase; slowly add the oil phase to the aqueous phase and emulsify in a high-speed homogenizer (10,000 rpm) for 15 minutes to form a stable emulsion;

[0087] S3: Slowly add an aqueous solution of ethylenediamine to the emulsion, and stir the mixture at 300 rpm in a constant temperature water bath at 60°C to obtain a reaction solution, so that the polyisocyanate and the polyamine undergo a condensation reaction at the oil-water interface to form a polyurea shell layer that covers the DBTDL droplets;

[0088] S4: The reaction solution is centrifuged, washed alternately with deionized water and ethanol three times, and dried under vacuum at 60° C. for 24 h to obtain DBTDL powder coated with polyurea microcapsules, i.e., microencapsulated catalyst.

[0089] A method for preparing a two-component polyurethane foam based on a microencapsulated catalyst comprises:

[0090] (1) Weigh each component according to the proportion;

[0091] (2) Preparation of component A: reacting polyether polyol with isocyanate at 90°C for 1.5 hours to generate a prepolymer, controlling the NCO content to 14%; adding the modified nanocomposite system, ultrasonically treating for 40 minutes, and then vacuum dehydrating to a moisture content of <0.05%;

[0092] (3) Preparation of component B: The polyether triol and filler were ball-milled for 3 hours, and the microencapsulated catalyst, foaming agent, and foam stabilizer were added at a shear rate of ≤500 rpm. After vacuum degassing, the mixture was sealed and stored.

[0093] (4) Component A and component B are mixed in a mass ratio of 1:1 to obtain polyurethane foam.

[0094] Comparative Example 1

[0095] The only difference from Example 1 is that the catalyst is dibutyltin dilaurate, which is not treated in any way.

[0096] Comparative Example 2

[0097] The only difference from Example 1 is that no nanofiller is added.

[0098] Comparative Example 3

[0099] The only difference from Example 1 is that the amount of nano-silica modified with a silane coupling agent is 0.2 parts, and the amount of carbon nanotubes is 1 part.

[0100] The properties of the polyurethane foams of Examples 1-2 and Comparative Examples 1-3 were tested, and the test methods were as follows:

[0101] Curing time: In five beakers, add 10 g of component A of the two-component polyurethane foam adhesive of each example and comparative example, then add 10 g of component B. Stir immediately until foaming begins. Record the time from the start of stirring to the time when the adhesive surface is lightly touched with a finger. If no adhesive sticks to the finger, the corresponding time is the curing time.

[0102] Tensile strength test: Take five glass magnesium boards of the same material and five galvanized boards of the same material. Apply component A prepared in each example and comparative example to each of the five glass magnesium boards, and apply component B prepared in each example and comparative example to each of the five galvanized boards. Adhere the corresponding glass magnesium boards and galvanized boards, mix the components A and B prepared in each example and comparative example, and clamp them for 5 minutes before starting the timer. After 24 hours, separate the glass magnesium boards and galvanized boards, and observe the surface damage of the glass magnesium boards.

[0103] Heat aging test: Take 5 glass magnesium boards of the same material and 5 boards of the same material. Apply component A prepared in each example and comparative example to 5 galvanized sheets, and apply component B prepared in each example and comparative example to 5 glass magnesium boards. Adhere the corresponding glass magnesium boards and galvanized sheets, mix the components A and B in each example and comparative example, clamp them with a clamp for 5 minutes, then start timing. After 48 hours at 95°C, separate the glass magnesium boards and galvanized sheets, and observe the surface damage of the glass magnesium boards.

[0104] Performance Testing

[0105] The test results are shown in Table 1.

[0106] Table 1 Performance test results of polyurethane foams of Examples 1-2 and Comparative Examples 1-3

[0107]

[0108] The above data show that Examples 1-2 have shorter curing times than Comparative Example 1, demonstrating that the microcapsule shear-triggered mechanism can enhance the reaction rate. In Comparative Example 2, the absence of nanoreinforcement results in weak interface bonding, resulting in no damage. In Comparative Example 3, the SiO2:CNT ratio is 1:5, and the excessive carbon nanotubes induce agglomeration, leading to stress concentration and, in turn, localized debonding at the interface.

[0109] Those skilled in the art will appreciate that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A two-component polyurethane foam based on microencapsulated catalyst, characterized in that: Prepared by mixing component A and component B; The component A includes polyether polyol, isocyanate and modified nanocomposite system; The B component includes polyether triol, a foaming agent and a microencapsulated catalyst, wherein the microencapsulated catalyst is dibutyltin dilaurate coated with a polyurea shell; The B component is introduced into the microencapsulated catalyst through a low-speed dispersion process before mixing, and the polyurea shell layer is broken by mechanical shear force during mixing to release dibutyltin dilaurate.

2. A two-component polyurethane foam based on a microencapsulated catalyst according to claim 1, characterized in that: The modified nanocomposite system is composed of nano-silica modified by a silane coupling agent and carbon nanotubes in a mass ratio of 2.5-3.5:

1.

3. A two-component polyurethane foam based on a microencapsulated catalyst according to claim 2, characterized in that: The silane coupling agent modified nano-silica is obtained by immersing the nano-silica in an aminosilane coupling agent-ethanol solution with a mass concentration of 1% to modify the nano-silica.

4. A two-component polyurethane foam based on a microencapsulated catalyst according to claim 2, characterized in that: The component A also includes a dehydrating agent. Calculated by weight, the component A includes: 30-50 parts of polyether polyol, 50-60 parts of isocyanate, 0.5-1 parts of silane coupling agent modified nano-silica, 0.2-0.5 parts of carbon nanotubes, and 3-4 parts of dehydrating agent.

5. The two-component polyurethane foam based on microencapsulated catalyst according to claim 1, characterized in that: The B component also includes a foam stabilizer and a filler. Calculated by weight, the B component includes: 40-60 parts of polyether triol, 8-12 parts of foaming agent, 0.5-1 part of microencapsulated catalyst, 0.5-1 part of foam stabilizer, and 20-40 parts of filler.

6. The two-component polyurethane foam based on microencapsulated catalyst according to claim 1, characterized in that: The mass ratio of the component A to the component B is 0.8-1.2:

1.

7. The two-component polyurethane foam based on microencapsulated catalyst according to claim 1, characterized in that: The shear rate of the low-speed dispersion process is ≤500 rpm.

8. The two-component polyurethane foam based on microencapsulated catalyst according to claim 1, characterized in that: The microencapsulated catalyst is prepared by an interfacial polymerization method, comprising: S1 dissolves dibutyltin dilaurate and polyisocyanate in a hydrophobic solvent to form an oil phase; S2 adds the oil phase to the water phase containing the emulsifier for emulsification; S3: adding a polyamine aqueous solution to the emulsion, polycondensing at the oil-water interface to form a polyurea shell layer, which covers the dibutyltin dilaurate droplets; S4: centrifuging, washing, and drying the reaction solution to obtain the microencapsulated catalyst.

9. A method for preparing a two-component polyurethane foam based on a microencapsulated catalyst, characterized in that: include: (1) Weigh each component according to the proportion; (2) Preparation of component A: reacting polyether polyol with isocyanate to form a prepolymer, controlling the NCO content to 12-14%; adding the modified nanocomposite system and dehydrating; (3) Preparation of component B: ball-mill the polyether triol and filler, add the microencapsulated catalyst, foaming agent, and foam stabilizer at a shear rate of ≤500 rpm, vacuum degass, and seal for storage; (4) Mixing the component A with the component B to obtain a polyurethane foam.

10. The method for preparing a two-component polyurethane foam based on a microencapsulated catalyst according to claim 9, characterized in that: In step (2), the polyether polyol and isocyanate are reacted at 70-90° C. for 1.5-2.5 hours, and the NCO content is controlled at 12-14%. The modified nanocomposite system is added, ultrasonically treated for 30-40 minutes, and vacuum dehydrated to a moisture content of <0.05%.

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