Multifunctional polyurethane foam glue as well as preparation and application methods thereof

Abstract

The invention discloses a multifunctional polyurethane foam adhesive and preparation and application methods thereof, the multifunctional polyurethane foam adhesive comprises a main agent component A and a curing agent component B. The component A comprises, by mass, 35-90 parts of polyether polyol, 1-3 parts of a flexibilizer, 5-15 parts of triptolide powder, 1-5 parts of a foaming agent and 1-3 parts of a surfactant; the component B is prepared from 75 to 100 parts of polyisocyanate, 0.05 to 2 parts of a composite catalyst, 2 to 10 parts of a cross-linking agent, 9 to 20 parts of an organic flame retardant, 8 to 15 parts of an inorganic flame retardant and 1 to 10 parts of graphite powder; wherein the composite catalyst is obtained by compounding A-33 and DBTDL, and integration of multiple functions of flame retardance, insect prevention, rapid curing and the like is realized.

Description

Technical Field

[0001] This invention belongs to the field of polyurethane foam adhesive technology, specifically relating to a multifunctional polyurethane foam adhesive and its preparation and application methods. Background Technology

[0002] Polyurethane foam, with its excellent foaming rate, superior expansion and filling capabilities, good sealing properties, and convenient construction characteristics, has become a core material in modern construction, electromechanical installation, pipe penetration sealing, door and window installation, and thermal insulation filling. It can expand and cure quickly, filling complex gaps and providing good airtightness, watertightness, and a certain degree of thermal and sound insulation. However, with continuously improving building safety standards (especially fire protection requirements), increasingly complex application scenarios (such as underground spaces, areas with dense cable networks, humid environments, and areas with rodent and insect infestations), and heightened public concern for building durability and maintenance costs, the performance shortcomings of traditional polyurethane foam are becoming increasingly apparent, making it difficult to meet higher standards of comprehensive performance requirements. The main deficiencies of currently available commercially available foams are as follows: 1. Poor flame retardant properties: Ordinary polyurethane foam is essentially a combustible material with a low limiting oxygen index. It is easily ignited by a source of ignition and burns rapidly. During combustion, it not only releases a large amount of heat, but more fatally, it produces high concentrations of toxic fumes (such as carbon monoxide, hydrogen cyanide, nitrogen oxides, etc.) and soot, failing to meet high fire protection standards. 2. Weak rodent and insect control: Conventional polyurethane foam has a relatively loose texture, and its odor or composition lacks deterrent effect or physical barrier effect on rodents (rats) and insects (termites, cockroaches, etc.). In areas such as cable penetration holes, underground tunnels, and equipment bases, small animals can easily gnaw and damage the foam, causing sealing failure or electrical safety hazards. 3. Insufficient moisture resistance: The water absorption of polyurethane foam is closely related to its cell structure (open cell ratio). When ordinary or partially open-cell foam is exposed to a humid environment or in direct contact with water, its water absorption rate is high, its airtightness decreases, and thus its service life is short.

[0003] 4. Poor strength: Ordinary expanding foams pursue high foaming rates and rapid curing, often at the expense of final strength. After curing, the foam has low density, thin walls, and insufficient cross-linking density, resulting in low strength. It cannot bear weight for long periods and is prone to aging and detachment.

[0004] In summary, existing polyurethane foam adhesives have significant shortcomings in terms of flame retardancy, resistance to biological damage, water resistance, and long-term mechanical strength, making it difficult to meet the demands of modern high-standard building safety, durability, and complex application scenarios. Therefore, there is an urgent need to develop a new type of polyurethane foam adhesive that integrates high strength, high flame retardancy, low smoke toxicity, effective rodent and insect prevention, and excellent waterproof and moisture-proof performance, while maintaining a good foaming rate and ease of construction. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0007] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a multifunctional polyurethane foam adhesive.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: the multifunctional polyurethane foam adhesive is composed of main component A and curing agent component B, in parts by mass, Component A includes 35-90 parts of polyether polyol, 1-3 parts of toughening agent, 5-15 parts of triptolide powder formed by in-situ polymerization of urea-formaldehyde resin, 1-5 parts of foaming agent, and 1-3 parts of surfactant. Component B comprises 75-100 parts of polymeric isocyanate, 0.05-2 parts of composite catalyst, 2-10 parts of crosslinking agent, 9-20 parts of organic flame retardant, 8-15 parts of inorganic flame retardant, and 1-10 parts of graphite powder. The composite catalyst is prepared by compounding A-33 and DBTDL in a mass ratio of 2:1 to 4:3. A-33 is prepared by 33% triethylenediamine and 67% dipropylene glycol, and DBTDL is dibutyltin dilaurate.

[0009] It should be noted that triptolide powder is one of the characteristic components of this invention. Its repellent and toxic properties prevent rodents and insects from gnawing on the vesicles, thereby ensuring the stability of the sealing. It is derived from an extract of the roots of Tripterygium wilfordii, and its typical chemical formula is C. 20 H 24 O6 is lipophilic and volatile, and achieves a long-lasting repellent effect through slow release in the foam. It has advantages such as slow volatilization and long duration of effect.

[0010] Tripterygium wilfordii can be encapsulated in microcapsules (e.g., using urea-formaldehyde resin, gelatin-glutaraldehyde, or chitosan as wall materials). Its shell has good thermal stability and hydrophobicity, and the active components are gradually released during the temperature rise (40-65°C) of the foaming and curing process, thereby extending its effective time and effective repellency cycle (>18 months) and improving its durability and resistance to biological damage in the plugging system.

[0011] Specifically, this invention uses urea-formaldehyde resin for in-situ polymerization coating. Tripterygium wilfordii is uniformly dispersed in an aqueous phase containing an emulsifier. Urea and formaldehyde are added, and the pH is adjusted to 2.5–3.5, then heated to 50–60°C to induce condensation of the urea-formaldehyde on the core material surface, resulting in microcapsule powder with a particle size of 10–50 μm. The capsule walls formed by this treatment remain stable during the polyurethane reaction curing process and slowly release repellent components in the usage environment, achieving a long-lasting insect and rodent repellent effect for more than 18 months.

[0012] As a preferred embodiment of the multifunctional polyurethane foam adhesive of the present invention, the polyether polyol has a functionality of 2.5 to 3.5 and a hydroxyl value of 300 to 500 mg KOH / g.

[0013] It should be noted that polyether polyol, as the basic skeleton component of the multifunctional polyurethane foam adhesive in this application, determines the softness and bonding ability of the foam.

[0014] In a preferred embodiment of the multifunctional polyurethane foam adhesive of the present invention, the toughening agent is acrylate rubber.

[0015] It should be noted that acrylate rubber toughening agents are used to improve the brittleness of foams, enhance their impact and bending resistance, improve their fatigue resistance, and prevent aging cracking.

[0016] As a preferred embodiment of the multifunctional polyurethane foam adhesive of the present invention, the foaming agent includes one of water, CFC-11, HCFC-141b or cyclopentane.

[0017] It should be noted that the foaming agent reacts with MDI to generate CO2, forming a microbubble structure.

[0018] As a preferred embodiment of the multifunctional polyurethane foam adhesive of the present invention, the surfactant is an organosilicon silicone oil, including L-580 and DC-198.

[0019] It should be noted that silicone oil controls bubble size and uniformity, and enhances flowability.

[0020] In a preferred embodiment of the multifunctional polyurethane foam adhesive of the present invention, the crosslinking agent is glycerol.

[0021] As a preferred embodiment of the multifunctional polyurethane foam adhesive of the present invention, wherein: the organic flame retardant includes TCPP or TCEP, and the inorganic flame retardant is aluminum hydroxide.

[0022] It should be noted that organic flame retardants can participate in the reaction, improving flame retardant performance and releasing expandable gaseous flame-retardant factors. Inorganic flame retardants can absorb heat and lower the temperature, forming a shielding inert layer that prevents the spread of flames. Expanded graphite expands in volume under the high temperature of a fire to form a carbon layer, cutting off the heat source and oxygen, further significantly improving the fire resistance rating of the foam.

[0023] As a preferred embodiment of the multifunctional polyurethane foam adhesive of the present invention, wherein: component A of the multifunctional polyurethane foam adhesive further includes 0.2 to 1 part of hydrophobic nanoparticles, 0.5 to 2 parts of a self-healing monomer containing a dynamic hydrogen bond structure, including a hydroxyl-terminated polyether-polyurea block polymer, and 0.5 to 2 parts of a fluorinated surface modifier; component B of the multifunctional polyurethane foam adhesive further includes 1 to 3 parts of a phosphorus-nitrogen synergistic intumescent flame retardant, including melamine polyphosphate.

[0024] It should be noted that, in order to enable the microcracks caused by vibration or thermal expansion and contraction during use to self-close, 0.5 to 2 parts by weight of a self-healing monomer with a dynamic hydrogen bond structure, such as a hydroxyl-terminated polyether-polyurea block polymer, can be added to group A. This monomer can achieve dynamic rearrangement of chain segments at ambient temperature, slowly repairing microcracks on the surface and inside of the bubble, thereby effectively extending its sealing life and ensuring its water tightness and air tightness.

[0025] To further enhance the moisture-proof performance of the foam, 0.5 to 2 parts of a fluorinated surface modifier (such as fluorinated polyether or fluorosilicone ether) can be added. After the foam is cured, this component forms a hydrophobic film structure on the pore wall surface, which can significantly reduce the permeability of water vapor, thereby enhancing the long-term stability of the foam in underground and high-humidity environments.

[0026] Another object of the present invention is to provide a method for preparing a multifunctional polyurethane foam adhesive.

[0027] To solve the above-mentioned technical problems, the present invention provides the following technical solutions, including: After mixing raw material A and passing it through a 20-50 mesh vibrating sieve, it is placed in a reaction vessel for degassing treatment for 20-40 minutes. Component B is mixed evenly; Components A and B are injected into moisture-proof and pressure-resistant packaging bottles and stored away from light and moisture to obtain a multifunctional polyurethane foam adhesive ready for use.

[0028] Another object of the present invention is to provide a method for applying a multifunctional polyurethane foam adhesive.

[0029] To solve the above-mentioned technical problems, the present invention provides the following technical solution, including simultaneously dispensing component A and component B in a 1:1 volume ratio using a two-component glue gun, mixing them and immediately injecting them into the gap; The gaps include gaps in concrete, brick walls, and steel plates.

[0030] Beneficial effects of this invention: 1. The dual-catalytic system (A-33 and DBTDL) combined with a low activation energy reaction formula enables the foam to bubble within 5-12 seconds, achieve surface drying in about 35 seconds, and initially solidify in 1 hour, greatly shortening the construction waiting time and making it suitable for rapid sealing operations or emergency repairs.

[0031] 2. Under the synergistic effect of crosslinking agents, toughening agents and high-functionality polyether polyols, the foam forms a three-dimensional network structure with a compressive strength of up to 2.26 MPa and an adhesive strength of up to 1.8 MPa. It can withstand vertical loads such as cables and pipes for a long time and avoid problems such as falling off and sinking.

[0032] 3. By using a composite flame retardant system consisting of organophosphorus flame retardants (TCPP / TCEP), inorganic fillers (aluminum hydroxide), and expanded graphite, a triple fire protection mechanism of "gas phase inhibition + char layer insulation + expansion flame retardancy" is constructed, enabling the foam to maintain structural stability even at a high temperature of 750℃.

[0033] 4. By adding triptolide powder as a natural rodent and insect repellent component, it can effectively repel animals such as rats, cockroaches, and ants for a long time. It is especially suitable for high-risk environments with biological damage, such as cable tunnels and low-voltage wells, reducing safety hazards.

[0034] 5. Tripterygium wilfordii is encapsulated in microcapsules, which gradually release the active components during the temperature rise of the foaming and curing process, thereby extending its effective time and repellency cycle, and improving its durability and resistance to biological damage in the plugging system. Detailed Implementation

[0035] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0036] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0037] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0038] Unless otherwise specified, all raw materials used in this invention are commercially available in the field.

[0039] The preparation method of the triptolide powder formed by in-situ polymerization of urea-formaldehyde resin in a specific embodiment of the present invention is as follows: In a stirred reactor, triptolide powder (purity ≥98%) is uniformly dispersed in an aqueous phase containing an emulsifier (such as OP-10); Add urea and formaldehyde to make the molar ratio of urea to formaldehyde 1:2, and adjust the pH of the system to 2.5-3.5. Heating to 55℃ and reacting for 75 minutes allows urea-formaldehyde resin to condense in situ on the surface of triptolide particles to form a coating layer. After the reaction was completed, the mixture was cooled, filtered, washed, and dried to obtain triptolide microcapsule powder with a particle size of about 30 μm.

[0040] The microcapsule powder has good thermal stability and hydrophobicity, can remain stable during the polyurethane foaming and curing process, and slowly releases the active ingredient tripterygium wilfordii during use, thus achieving a long-lasting insect and rodent repellent effect for more than 18 months.

[0041] The present invention tests the properties of expanding foam using the following method: Flame retardancy test: Passed the test according to GB8624-2012 standard.

[0042] Insect and rodent control experiment: simulating a scenario of rodents gnawing.

[0043] Waterproof test: The sample was completely immersed in water for 72 hours, dried, weighed, and the rate of change in mass and apparent change were recorded.

[0044] Foaming efficiency: Foaming is carried out in a graduated cylinder, and the final foaming volume and the initial mixture volume are recorded to calculate the expansion ratio. At the same time, the surface drying / initial solidification time is recorded.

[0045] Compressive strength: A cube of a specific size was prepared and compressed at a deformation rate of 10% / min to obtain the strength at the yield / 10% deformation of the stress-strain curve.

[0046] Bond strength: Record the maximum shear strength.

[0047] Bending strength: The material is made into a strip and then pressure is applied across the mid-span until it breaks to obtain bending strength.

[0048] Water absorption rate: The sample was dried and weighed (A), then soaked in water for 72 h, removed, dried and weighed (B), and the water absorption rate was calculated.

[0049] Closed-pore ratio: Apparent volume and open-pore volume fraction were determined using the gas displacement method.

[0050] Example 1 This embodiment provides a high-strength, flame-retardant, insect- and rodent-proof, waterproof multifunctional polyurethane foam adhesive, its preparation and application methods, specifically: 1) The multifunctional polyurethane foam adhesive is composed of main component A and curing agent component B. Component A and component B shall be weighed according to the following formula in parts by mass; Component A: 85 parts polyether polyol (polyether 330N, functionality = 3, hydroxyl value 350mgKOH / g), 2 parts toughening agent (acrylate rubber), 5 parts triptolide powder coated by in-situ polymerization of urea-formaldehyde resin, 1 part water (foaming agent), 1.5 parts surfactant (organosilicon silicone oil, L-580). Component B: 100 parts of polymeric isocyanate (polymeric MDI, NCO content 31.5%), 1 part of catalyst (A-33 and DBTDL compounded in a 3:2 ratio), 6 parts of crosslinking agent (glycerol), 10 parts of TCPP (organic flame retardant), 10 parts of inorganic flame retardant (aluminum hydroxide), and 10 parts of graphite.

[0051] 2) Preparation of multifunctional polyurethane foam adhesive: The raw material A, weighed according to the proportion, is mixed and pretreated by passing through a 30-mesh vibrating sieve to improve the dispersibility of the raw material. After being placed in a reaction vessel for degassing for 30 minutes, it is injected into a moisture-proof and pressure-resistant packaging bottle. Component B, weighed according to the proportion, is mixed evenly and then injected into a moisture-proof and pressure-resistant packaging bottle. After components A and B are separately injected into moisture-proof and pressure-resistant packaging bottles, they should be stored away from light and moisture until use, at a temperature of 10~30℃.

[0052] 3) Applications of multifunctional polyurethane foam adhesives: When using, component A and component B are simultaneously dispensed at a 1:1 volume ratio using a two-component glue gun, mixed, and immediately injected into the gap. Under conditions of 25°C and 50%RH, the glue prepared in this embodiment has a foaming time of 7s, a surface drying time of 35s, an initial curing time of 60s, a compressive strength of 2.26MPa, and an adhesive strength of 1.8MPa.

[0053] Testing revealed that the oxygen index of the polyurethane foam adhesive in this application was increased to 32%, achieving UL94 V-0 certification. Compared to traditional brominated flame retardants, smoke emission was reduced by 60%, complying with EU RoHS 2.0 standards. Laboratory tests showed a 98% knockdown rate against German cockroaches and black-breasted cockroaches, a 90% repellency rate against rodents, and an effective protection period extended to 5 years. The foaming ratio reached up to 8 times, with an instantaneous foaming rate of 85%, and a curing time shortened to 10 minutes (at 25°C). By adjusting the closed-cell ratio to over 90% and modifying it with hydrophobic groups, the water absorption rate was less than 1%, meeting the IP68 protection rating.

[0054] Example 2 This embodiment is a further optimization based on Example 1. Component A and component B are weighed according to the following formula; Component A: 85 parts polyether polyol (polyether 330N, functionality = 3, hydroxyl value 350 mg KOH / g), 2 parts toughening agent (acrylate rubber), 5 parts triptolide powder coated by in-situ polymerization of urea-formaldehyde resin, 1 part water (foaming agent), 1.5 parts surfactant (organosilicon silicone oil, L-580); 0.5 parts hydrophobic nanoparticles, 1 part self-healing monomer with dynamic hydrogen bond structure (hydroxyl-terminated polyether-polyurea block monomer), 1 part fluorinated surface modifier (perfluoropolyether surfactant). Component B includes: 100 parts of polymeric isocyanate (polymeric MDI, NCO content 31.5%), 1 part of catalyst (A-33 and DBTDL compounded in a 3:2 ratio), 6 parts of crosslinking agent (glycerol), 10 parts of TCPP (organic flame retardant), 10 parts of inorganic flame retardant (aluminum hydroxide), 10 parts of graphite, and 2 parts of phosphorus-nitrogen synergistic intumescent flame retardant (melamine polyphosphate). The adhesive prepared according to Example 1 was applied. The results showed that under the conditions of 25°C and 50%RH, the foaming time of the adhesive prepared in this example was 8 s; the surface drying time was 36 s; the initial curing time was 65 s; the compressive strength was 2.30 MPa; the bond strength was 1.85 MPa; the water absorption rate was 0.6%; the closed-cell rate was 90%; and no cracks appeared on the surface after one month of damp heat cycling. The fracture elongation recovery rate of the self-healing specimen reached 95%.

[0055] This is because the hydrophobic nanoparticles in this embodiment can form a micron-nano-scale layered barrier on the bubble wall surface, significantly improving moisture resistance; the terminal hydroxyl polyether-polyurea block monomer with dynamic hydrogen bond structure can rearrange chain segments at ambient temperature, achieving self-healing of microcracks; the fluorinated surface modifier migrates to the pore wall during the curing process, forming a low surface energy hydrophobic layer, significantly reducing water vapor permeability; melamine polyphosphate (MPP) forms a "phosphorus-nitrogen-carbon" composite flame retardant system with TCPP and graphite, enabling the bubble to maintain structural stability under high temperature conditions.

[0056] Comparative Example 1 The difference between this comparative example and Example 1 is that the catalyst in component B is adjusted to 0.8 parts DBTDL, while the rest of the formulation and process are the same as in Example 1, to obtain the foam adhesive of this comparative example.

[0057] Under conditions of 25℃ and 50%RH, the adhesive prepared in this comparative example has a foaming time of 15s, a surface drying time of 65s, an initial curing time of 130s, a compressive strength of 1.5MPa, and an adhesive strength of 1.2MPa.

[0058] Comparative Example 2 The difference between this comparative example and Example 1 is that the mass ratio of A-33 and DBTDL in the catalyst of component B is adjusted to 1:4. The rest of the formulation and process are the same as in Example 1, and the foam adhesive of this comparative example is obtained.

[0059] Under conditions of 25℃ and 50%RH, the adhesive prepared in this comparative example has a foaming time of 9s, a surface drying time of 52s, an initial curing time of 100s, a compressive strength of 1.65MPa, and an adhesive strength of 1.35MPa.

[0060] The performance of foam adhesives prepared with different catalyst components was compared, and the results are shown in Table 1.

[0061] Table 1

[0062] As shown in Table 1, the properties of the foam adhesive were significantly reduced when using a single catalyst or adjusting the proportion of the compound catalyst. When using a single DBTDL catalyst, foaming and curing were significantly slower, the foam structure was looser, and both compressive strength and adhesive strength deteriorated. This is because in Example 1 of this application, A33 is a tertiary amine catalyst, which preferentially promotes the reaction between -NCO and hydroxyl groups, accelerating the main chain crosslinking rate; DBTDL is a tin catalyst, which promotes the reaction between -NCO and water to release CO2 and form a foam structure. The combination of the two can achieve the simultaneous advancement of the main chain crosslinking and foaming process, thereby avoiding the situation of "fast foaming but slow crosslinking" or "fast crosslinking but no foaming", making the reaction rate gradient more balanced and promoting uniform foaming.

[0063] In contrast, due to the significantly increased proportion of DBTDL in Comparative Example 2, the foaming process took precedence over the main chain crosslinking reaction. This resulted in insufficient crosslinking support in the early stages of foam expansion, leading to increased foam diameter and partial collapse, ultimately resulting in reduced strength and uniformity. In comparison, the foaming and main chain reactions in the compounding ratio of Example 1 were able to establish a better synchronization relationship, resulting in a more stable foam structure and better performance. This indicates that the catalyst ratio has a more significant synergistic effect.

[0064] Comparative Example 3 The difference between this comparative example and Example 1 is that the acrylate rubber in component A is omitted, while the rest of the formulation and process are the same as in Example 1, to obtain the foam adhesive of this comparative example.

[0065] Under conditions of 25℃ and 50%RH, the adhesive prepared in this comparative example had a foaming time of 7s, a surface drying time of 37s, an initial curing time of 63s, a compressive strength of 2.18MPa, and a flexural strength of 0.49MPa.

[0066] Comparative Example 4 The difference between this comparative example and Example 1 is that the acrylate rubber in component A is replaced with TPU elastomer, while the rest of the formulation and process are the same as in Example 1, to obtain the foam adhesive of this comparative example.

[0067] Under conditions of 25℃ and 50%RH, the adhesive prepared in this comparative example has a foaming time of 8s, a surface drying time of 38s, an initial curing time of 65s, a compressive strength of 1.9MPa, a flexural strength of 0.49MPa, and an adhesive strength of 1.4.

[0068] Table 2 shows a comparison of the performance of the foam adhesives prepared in Comparative Examples 3 and 4 with that in Example 1.

[0069] Table 2

[0070] As can be seen from Table 2, after omitting or replacing the toughening agent, the overall foaming and curing time of the foam adhesive does not change much, but the flexibility and bonding strength decrease significantly, and the tendency to crack is weakened. Therefore, the toughening agent of this application plays a key role in improving the crack resistance and service life of the foam.

[0071] Comparative Example 5 The difference between this comparative example and Example 1 is that glycerol in component B is omitted, while the rest of the formulation and process are the same as in Example 1, resulting in the foam adhesive of this comparative example.

[0072] Under conditions of 25℃ and 50%RH, the adhesive prepared in this comparative example has a foaming time of 7s, a surface drying time of 35s, an initial curing time of 62s, a compressive strength of 1.58MPa, an adhesive strength of 1.3MPa, and a water absorption rate of 2.1%.

[0073] Comparative Example 6 The difference between this comparative example and Example 1 is that glycerol in component B is replaced with trimethylolpropane (TMP), while the rest of the formulation and process are the same as in Example 1, resulting in the foam adhesive of this comparative example.

[0074] Under conditions of 25℃ and 50%RH, the adhesive prepared in this comparative example has a foaming time of 8s, a surface drying time of 38s, an initial curing time of 65s, a compressive strength of 2.0MPa, an adhesive strength of 1.4MPa, and a water absorption rate of 2.0%.

[0075] Table 3 shows a comparison of the performance of the foam adhesives prepared in Comparative Examples 5 and 6 with that in Example 1.

[0076] Table 3

[0077] As can be seen from the comparison in Table 3, omitting the glycerol crosslinking agent reduces the degree of crosslinking of the foam, worsens the structural stability and density, increases the water absorption rate, and reduces the bonding performance, which seriously affects the structural strength and sealing ability of the foam. Replacing it with TMP will result in problems such as decreased adhesion, reduced closed-cell rate, and excessively high process viscosity. Therefore, it can be seen that glycerol is the best match for the dual-catalyst system, which can form a dense crosslinked network while maintaining the process fluidity.

[0078] Comparative Example 7 The difference between this comparative example and Example 1 is that the polyether polyol in component A of Example 1 is replaced with a common polyether polyol with a functionality of 2.0 and a hydroxyl value of 150 mg KOH / g. The rest of the formulation and process are the same as in Example 1, and the foam adhesive of this comparative example is obtained.

[0079] Under conditions of 25℃ and 50%RH, the adhesive prepared in this comparative example has a foaming time of 8s, a surface drying time of 38s, an initial curing time of 65s, a compressive strength of 1.3MPa, an adhesive strength of 1.1MPa, and a closed-cell rate of 72%.

[0080] The performance comparison of the foam adhesive prepared in this comparative example with that of Example 1 is shown in Table 4.

[0081] Table 4

[0082] As can be seen from Table 4, the structural characteristics of the basic skeleton polyether polyol directly affect the integrity of the three-dimensional network skeleton of the foam. Insufficient cross-linking network formed by low-functionality polyether will lead to loose foam, reduced strength, and lower closed-cell rate, which in turn will lead to a decrease in water tightness and durability.

[0083] Example 3 The difference between this embodiment and Embodiment 1 is that the formulations of components A and B are adjusted as follows: Component A: 35 parts polyether polyol (polyether 330N, functionality = 3, hydroxyl value 350mgKOH / g), 1 part toughening agent (acrylate rubber), 5 parts triptolide powder formed by in-situ polymerization of urea-formaldehyde resin, 1 part water (foaming agent), 1 part surfactant (organosilicon silicone oil, L-580). Component B: 75 parts of polymeric isocyanate (polymeric MDI, NCO content 31.5%), 0.05 parts of catalyst (A-33 and DBTDL compounded in a 3:2 ratio), 2 parts of crosslinking agent (glycerol), 9 parts of TCPP (organic flame retardant), 8 parts of inorganic flame retardant (aluminum hydroxide), and 1 part of graphite.

[0084] The multifunctional polyurethane foam adhesive of this embodiment was prepared according to the method in Example 1.

[0085] Example 4 The difference between this embodiment and Embodiment 1 is that the formulations of components A and B are adjusted as follows: Component A: 90 parts polyether polyol (polyether 330N, functionality = 3, hydroxyl value 350mgKOH / g), 3 parts toughening agent (acrylate rubber), 15 parts triptolide powder formed by in-situ polymerization of urea-formaldehyde resin, 5 parts water (foaming agent), 3 parts surfactant (organosilicon silicone oil, L-580). Component B: 100 parts of polymeric isocyanate (polymeric MDI, NCO content 31.5%), 2 parts of catalyst (A-33 and DBTDL compounded in a 3:2 ratio), 10 parts of crosslinking agent (glycerol), 20 parts of TCPP (organic flame retardant), 15 parts of inorganic flame retardant (aluminum hydroxide), and 10 parts of graphite.

[0086] The multifunctional polyurethane foam adhesive of this embodiment was prepared according to the method in Example 1.

[0087] Example 5 The difference between this embodiment and Example 1 is that the ratio of catalyst A-33 to DBTDL is adjusted to 2:1, while the rest of the formulation and process are the same as in Example 1, resulting in the multifunctional polyurethane foam adhesive of this embodiment.

[0088] Example 6 The difference between this embodiment and Example 1 is that the ratio of catalyst A-33 to DBTDL is adjusted to 4:5, while the rest of the formulation and process are the same as in Example 1, resulting in the multifunctional polyurethane foam adhesive of this embodiment.

[0089] According to the measurements, the performance indicators of the multifunctional polyurethane foam adhesives prepared in Examples 3 to 6 were slightly lower than those in Example 1, but were still better than those in the comparative examples.

[0090] In summary, the toughening agent in this invention mainly improves the flexibility and fatigue resistance of the foam, the crosslinking agent directly determines the crosslinking density and structural stability of the foam, and the high-functionality polyether polyol can construct a dense and tough skeleton. Only when the three are used in combination can a three-dimensional composite network of "high strength + flexibility + density" be formed.

[0091] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A multifunctional polyurethane foam adhesive, characterized in that: The multifunctional polyurethane foam adhesive is composed of main component A and curing agent component B, in parts by weight. Component A includes 35-90 parts of polyether polyol, 1-3 parts of toughening agent, 5-15 parts of triptolide powder formed by in-situ polymerization of urea-formaldehyde resin, 1-5 parts of foaming agent, and 1-3 parts of surfactant. Component B comprises 75-100 parts of polymeric isocyanate, 0.05-2 parts of composite catalyst, 2-10 parts of crosslinking agent, 9-20 parts of organic flame retardant, 8-15 parts of inorganic flame retardant, and 1-10 parts of graphite powder. The composite catalyst is prepared by compounding A-33 and DBTDL in a mass ratio of 2:1 to 4:

3. A-33 is prepared by 33% triethylenediamine and 67% dipropylene glycol, and DBTDL is dibutyltin dilaurate.

2. The multifunctional polyurethane foam adhesive as described in claim 1, characterized in that: The polyether polyol has a functionality of 2.5 to 3.5 and a hydroxyl value of 300 to 500 mg KOH / g.

3. The multifunctional polyurethane foam adhesive as described in claim 1, characterized in that: The toughening agent is acrylate rubber.

4. The multifunctional polyurethane foam adhesive as described in claim 1, characterized in that: The foaming agent includes one of water, CFC-11, HCFC-141b, or cyclopentane.

5. The multifunctional polyurethane foam adhesive as described in claim 1, characterized in that: The surfactant is an organosilicon silicone oil, including L-580 and DC-198.

6. The multifunctional polyurethane foam adhesive as described in claim 1, characterized in that: The crosslinking agent is glycerol.

7. The multifunctional polyurethane foam adhesive as described in claim 1, characterized in that: The organic flame retardant includes TCPP or TCEP, and the inorganic flame retardant is aluminum hydroxide.

8. The multifunctional polyurethane foam adhesive as described in any one of claims 1 to 7, characterized in that: Component A of the multifunctional polyurethane foam also includes 0.2 to 1 part of hydrophobic nanoparticles, 0.5 to 2 parts of self-healing monomers with dynamic hydrogen bond structures, including hydroxyl-terminated polyether-polyurea block polymers, and 0.5 to 2 parts of fluorinated surface modifiers; Component B of the multifunctional polyurethane foam also includes 1 to 3 parts of phosphorus-nitrogen synergistic intumescent flame retardant, including melamine polyphosphate.

9. The preparation method of the multifunctional polyurethane foam adhesive as described in claim 8, characterized in that: include, After mixing raw material A and passing it through a 20-50 mesh vibrating sieve, it is placed in a reaction vessel for degassing treatment for 20-40 minutes. Component B is mixed evenly; Components A and B are injected into moisture-proof and pressure-resistant packaging bottles and stored away from light and moisture to obtain a multifunctional polyurethane foam adhesive ready for use.

10. The application method of the multifunctional polyurethane foam adhesive prepared by the preparation method according to claim 9, characterized in that: Using a two-component glue gun, components A and B are simultaneously dispensed at a 1:1 volume ratio and mixed before being injected into the gap immediately. The gaps include gaps in concrete, brick walls, and steel plates.

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