Polyurethane modified epoxy resin adhesive, preparation method and application

Abstract

The invention discloses a polyurethane modified epoxy resin adhesive as well as a preparation method and application thereof, and the polyurethane modified epoxy resin adhesive is prepared from the following components in parts by mass: 7-10 parts of E51 type bisphenol A diglycidyl ether, 3.5 parts of a phenolic aldehyde amine T31 curing agent and 1-3 parts of synthetic polyurethane, the synthetic polyurethane is prepared from polyether triol, polyether amine, isophorone diisocyanate and glycerol carbonate, and a blending system of the synthetic polyurethane and bisphenol A diglycidyl ether is adopted to be subjected to covalent crosslinking with phenolic aldehyde amine T31, so that the adhesive has high toughness and strength guarantee; the synthetic polyurethane prepared by the method is obtained through simple, green and efficient solvent-free synthesis, and the synthesized product has certain fluidity at room temperature, so that the subsequent stirring preparation process of an adhesive is facilitated. And a solvent-free synthesis method is adopted, so that the use of a toxic organic solvent in the traditional polyurethane synthesis process is avoided, and the synthesis process is greener.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of adhesives, in particular to a polyurethane modified epoxy resin adhesive, a preparation method and applications thereof. BACKGROUND

[0002] The growing demand for sustainable building materials has drawn attention to wood due to its high strength-to-weight ratio, low energy consumption requirements, and reliable structural performance. However, the hygroscopicity and anisotropic properties of natural wood limit its application in complex structures. To overcome these limitations, the industry has developed heavy timber structural products, including cross-laminated timber, glued laminated timber, laminated veneer lumber, and large-size plywood, to address challenges such as size limitations, poor dimensional stability, and performance fluctuations. These innovations have driven the rapid development of modern wood structure buildings. At the same time, the widespread use of MT products has placed stringent requirements on structural adhesives.

[0003] Epoxy resin has become one of the most widely used thermosetting adhesives due to its excellent chemical stability, heat resistance, corrosion resistance, and strong bonding force. However, its highly cross-linked curing network results in significant brittleness, limited plastic deformation capacity, and internal stress induced by shrinkage, which limits its application in high-performance MT engineering due to insufficient crack resistance. In addition, the lack of glue during the manufacturing process of MT products and the difficulty in detecting early damage during use pose additional challenges, as such minor defects often evolve into catastrophic failures. Therefore, developing epoxy resin-based adhesives with both toughness enhancement and real-time defect visualization functions has become a core technical challenge in this field.

[0004] To overcome the inherent brittleness of epoxy resin, researchers have explored various modification methods, including adding rubber particles, thermoplastic plastics, nanofillers, hyperbranched polymers, liquid crystal polymers, and core-shell structures. These methods improve fracture toughness through mechanisms such as crack deflection, energy dissipation, and phase separation. However, these methods often face challenges in balancing mechanical properties, optimizing interfacial compatibility, or maintaining process simplicity. In addition, most systems require high-temperature curing to meet strength requirements, and research on strengthening and toughening room-temperature cured epoxy resins is still relatively scarce.

[0005] In addition to the improvement of mechanical properties, real-time detection of defects in building materials is attracting increasing attention. Traditional non-destructive testing methods (such as ultrasonic imaging, acoustic emission and infrared thermal imaging) usually require external equipment support, are costly, and have limited sensitivity to early micro-cracks. To overcome these limitations, researchers have incorporated functional units such as conductive fillers and mechanically color-changing groups into adhesive matrices, enabling them to generate electrical or colorimetric signals upon damage. However, these methods often have poor long-term signal stability under complex use conditions, and may compromise mechanical properties and interfacial compatibility with wood substrates. Recently, polymeric induced emission (AIE) luminophores have emerged as a new strategy for visualizing defects in adhesives. By integrating fluorescent units into adhesive matrices, AIE technology can produce visible light responses at the initial stage of micro-crack formation, enabling high-sensitivity real-time monitoring of adhesive defects. Unlike traditional probes that are susceptible to aggregation-induced quenching, AIE luminophores enhance brightness in the solid state, making them particularly suitable for opaque, fiber-rich substrates such as solid wood. This inherent compatibility allows defect signals to be detected within the adhesive layer or at the wood-adhesive interface, the most critical area for early crack initiation. In addition to stable optical output, the flexibility of AIE system design provides broad adjustability, highlighting its potential as a multifunctional epoxy resin adhesive in solid wood engineering. SUMMARY

[0006] This section is intended to summarize some aspects of the embodiments of the present application and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of the specification of the present application in order to avoid obscuring the purpose of this section, the abstract and the title, and such simplifications or omissions are not used to limit the scope of the present application.

[0007] Therefore, the purpose of the present application is to provide a polyurethane-modified epoxy resin adhesive, a preparation method and an application, in order to solve the problems raised in the background art.

[0008] To solve the above technical problems, according to one aspect of the present application, the present application provides the following technical solutions:

[0009] A polyurethane-modified epoxy resin adhesive, characterized in that it is composed of the following components in mass ratio: 7-10 parts of bisphenol A diglycidyl ether type E51, 3.5 parts of phenolic amine T31 curing agent and 1-3 parts of synthetic polyurethane.

[0010] As a preferred scheme of the polyurethane-modified epoxy resin adhesive according to the present application, the synthetic polyurethane is prepared from polyether triols, polyether amines, isophorone diisocyanate and glycerol carbonate.

[0011] As a preferred scheme of the polyurethane-modified epoxy resin adhesive, the ratio of the E51 type bisphenol A diglycidyl ether to the synthetic polyurethane is 8:2.

[0012] A preparation method of the polyurethane-modified epoxy resin adhesive, comprising the following steps:

[0013] S1, E51 type bisphenol A diglycidyl ether 7-10 parts, phenolic amine T31 curing agent 3.5 parts, and synthetic polyurethane 1-3 parts are weighed according to the mass ratio;

[0014] S2, the synthetic polyurethane is added to the E51 type bisphenol A diglycidyl ether;

[0015] S3, the phenolic amine T31 curing agent is uniformly dispersed in the synthetic polyurethane and the bisphenol A diglycidyl ether obtained in step S2, and then uniformly stirred at high speed to obtain a polyurethane-modified room temperature curing epoxy resin adhesive.

[0016] As a preferred scheme of the preparation method of the polyurethane-modified epoxy resin adhesive, the preparation steps of the synthetic polyurethane are as follows:

[0017] 61g, 0.02mol of polyether triol and 40g, 0.02mol of polyether amine D2000 are placed in a three-necked flask and placed in a 100℃ vacuum oven for 1.5h;

[0018] Then 22.2g, 0.1mol of isophorone diisocyanate is added, a few drops of catalyst is added, and the reaction is stirred in an 80℃ oil bath for 3h to obtain a prepolymer;

[0019] Then 11.8g, 0.1mol of glycerol carbonate is added for end capping reaction for 4h, and the whole synthesis process is carried out under nitrogen protection, and the reaction is confirmed to be completed by the disappearance of NCO absorption peak at 2271cm -1 in the Fourier transform infrared spectrum, and the obtained product is a synthetic polyurethane.

[0020] As a preferred scheme of the preparation method of the polyurethane-modified epoxy resin adhesive, the catalyst is dibutyltin dilaurate, and the amount is 0.1%-0.5% of the total mass of the raw materials.

[0021] The application relates to a polyurethane-modified epoxy resin adhesive prepared by a preparation method, and application of the polyurethane-modified epoxy resin adhesive in improving the immersion peeling resistance of glued wood. A hydroxymethylated resorcinol primer is coated on the surface of a wood board at a coating rate of 70-90 g / m2, and then a polyurethane-modified epoxy resin adhesive is coated after drying, at a coating rate of 300-400 g / m2; and after assembly along the fiber direction, cold pressing is carried out under a pressure of 0.8-1.2 MPa for 5-7 h.

[0022] As a preferred scheme of the application of the polyurethane-modified epoxy resin adhesive in improving the immersion peeling resistance of glued wood, the preparation steps of the hydroxymethylated resorcinol primer are as follows:

[0023] In the first stage, 361.72 g of deionized water and 13.36 g of resorcinol are uniformly mixed, and then 9.76 g of a sodium hydroxide solution is added;

[0024] First, 3.8 g of a formaldehyde solution is added, and 2 g of a dodecyl sodium sulfate salt is added at the same time, and reaction is carried out at 25 DEG C for 2 h, and the mixture is left to stand for 24 h;

[0025] In the second stage, 50 g of the solution after the reaction in the first stage is selected, 1.46 g of a formaldehyde solution is added, and after activation at 25 DEG C for 1 h, the solution is used.

[0026] As a preferred scheme of the application of the polyurethane-modified epoxy resin adhesive in improving the immersion peeling resistance of glued wood, the mass fraction of the sodium hydroxide solution is 10.8%.

[0027] Compared with the prior art, the application has the beneficial effects that:

[0028] 1. The application adopts a blending system of synthetic polyurethane and bisphenol A diglycidyl ether to covalently crosslink with phenolic amine T31, so that the adhesive has high toughness and strength.

[0029] 2. The synthetic polyurethane prepared by the application is obtained through a simple, green and efficient solvent-free synthesis method, and the product after synthesis has certain fluidity at room temperature, so that the subsequent stirring preparation process of the adhesive is facilitated. Moreover, the solvent-free synthesis method is adopted, the use of toxic organic solvents in the traditional polyurethane synthesis process is avoided, and the synthesis process is more green.

[0030] 3. The low-cost bisphenol A diglycidyl ether as the raw material of the adhesive, the synthesized polyurethane as the toughening agent of the epoxy resin, the dense hydrogen bond in the polyurethane enhances the aggregation-induced emission effect, and the adhesive realizes the blue fluorescent effect under the 365nm ultraviolet lamp under the aggregation-induced emission effect, realizes the function that the single-component polyurethane adhesive used in the mainstream of the wood structure market does not have, and the real-time adhesive detection function in the production process of the wood engineering product provides a train of thought for the advanced production of the MT product.

[0031] 4. The polyurethane modified epoxy resin adhesive and the hydroxymethylated resorcinol primer solution are used in the application, the micro-phase separation structure constructed by the polyurethane and the epoxy resin can significantly improve the toughness of the adhesive, effectively reduces the impregnated peeling rate of the glued wood after the impregnated peeling test; the modified epoxy resin adhesive improves the interfacial strength of the wood bonding through the non-covalent / covalent interaction between the hydroxymethylated resorcinol solution coated on the wood surface; in addition, the hydroxymethylated resorcinol with the micro-crosslinking property can play a role in stabilizing the size of the wood, further reducing the impregnated peeling rate of the glued wood. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the application, the application will be described in detail below with reference to the drawings and detailed embodiments. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can also be obtained by those skilled in the art without creative labor. Among them:

[0033] Figure 1 The synthetic polyurethane prepared by example 4 of the application has flowability at room temperature.

[0034] Figure 2 The appearance of the polyurethane modified epoxy resin adhesive prepared by example 4 of the application is shown in the figure.

[0035] Figure 3 The shear strength test of the two-layer glued wood prepared by examples 1-4 and comparative example 1 is shown in the figure, wherein 1 represents the product obtained by comparative example 1, 2 represents the product obtained by example 1, 3 represents the product obtained by example 2, 4 represents the product obtained by example 3, and 5 represents the product obtained by example 4.

[0036] Figure 4 The glue opening of the two-layer glued wood prepared by examples and comparative examples of the application after boiling water immersion test for two cycles is shown in the figure, wherein 1 represents the product obtained by comparative example 1, 2 represents the product obtained by example 1, 3 represents the product obtained by example 2, 4 represents the product obtained by example 3, and 5 represents the product obtained by example 4.

[0037] Figure 5 Table 1 is a comparison of the glue layer opening of two-layer glued wood prepared by the examples and the comparative examples of the present application after two cycles of cold water immersion test and drying, wherein 1 represents the product obtained by Comparative Example 1, 2 represents the product obtained by Example 1, 3 represents the product obtained by Example 2, 4 represents the product obtained by Example 3, and 5 represents the product obtained by Example 4.

[0038] Figure 6 Figure 2 is a phenomenon of the polyurethane-modified epoxy resin adhesive prepared by Example 2 of the present application coated on the surface of a veneer under the irradiation of visible light and 365 nm ultraviolet light.

[0039] Figure 7 Figure 3 is the flowability of the polyurethane-modified epoxy resin adhesive prepared by Example 2 of the present application poured on the surface of a veneer after uniform stirring under the irradiation of 365 nm ultraviolet light. DETAILED DESCRIPTION

[0040] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0041] Example 1

[0042] 1 g of synthetic polyurethane was mixed with 9 g of E51 type bisphenol A diglycidyl ether, then 3.5 g of phenolic amine curing agent was added and uniformly dispersed, and then uniformly stirred at high speed to obtain a polyurethane-modified room temperature curing epoxy resin adhesive.

[0043] The obtained adhesive was applied to the surface of a larch plywood with a water content of 12.4±0.4% after sanding with sandpaper by a single-sided coating method at a coating rate of 350 g / m 2 After coating, the veneer was assembled along the fiber longitudinal direction, and the glued wood was taken out after cold pressing for 6 h at a pressure of 1 MPa using a flat vulcanizing machine.

[0044] The preparation steps of the synthetic polyurethane are as follows:

[0045] Polyether polyol C3050 (PEO, 61 g, 0.02 mol) and polyether amine D2000 (PEA, 40 g, 0.02 mol) were placed in a three-necked flask and placed in a vacuum oven at 100°C for 1.5 h. Then, isophorone diisocyanate (IPDI, 22.2 g, 0.1 mol) was added, and dibutyl tin dilaurate (DBTDL, 0.32 g, 0.0005 mol) was added as a catalyst, and the reaction was carried out in an 80°C oil bath for 3 h to obtain a prepolymer. Then, glycerol carbonate (GC, 11.8 g, 0.1 mol) was added for end capping reaction for 4 h, and the entire synthesis process was carried out under nitrogen protection. The reaction was confirmed to be complete by disappearance of the NCO absorption peak (2271 cm -1 ) in the Fourier transform infrared spectrum, and the final reaction obtained the synthetic polyurethane.

[0046] Example 2

[0047] 2 g of the synthetic polyurethane was mixed with 8 g of bisphenol A diglycidyl ether of type E51, then 3.5 g of phenolic amine curing agent was uniformly dispersed, and then uniformly stirred at high speed to obtain a polyurethane modified room temperature curing epoxy resin adhesive.

[0048] The obtained adhesive was applied to the fir plywood with a water content of 12.4±0.4% after sanding by single-sided coating method at a coating rate of 350 g / m 2 After coating, the veneer was assembled along the fiber longitudinal direction, and the glued wood was taken out after cold pressing at 1 MPa pressure for 6 h using a flat vulcanizing machine.

[0049] The preparation steps of the synthetic polyurethane are as follows:

[0050] Polyether polyol C3050 (PEO, 61 g, 0.02 mol) and polyether amine D2000 (PEA, 40 g, 0.02 mol) were placed in a three-necked flask and placed in a vacuum oven at 100°C for 1.5 h. Then, isophorone diisocyanate (IPDI, 22.2 g, 0.1 mol) was added, and dibutyl tin dilaurate (DBTDL, 0.32 g, 0.0005 mol) was added as a catalyst, and the reaction was carried out in an 80°C oil bath for 3 h to obtain a prepolymer. Then, glycerol carbonate (GC, 11.8 g, 0.1 mol) was added for end capping reaction for 4 h, and the entire synthesis process was carried out under nitrogen protection. The reaction was confirmed to be complete by disappearance of the NCO absorption peak (2271 cm -1 ) in the Fourier transform infrared spectrum, and the final reaction obtained the synthetic polyurethane.

[0051] Example 3

[0052] 3 g of the synthetic polyurethane was mixed with 7 g of bisphenol A diglycidyl ether of type E51, then 3.5 g of phenolic amine curing agent was uniformly dispersed, then uniformly stirred at high speed to obtain a polyurethane modified room temperature curing epoxy resin adhesive.

[0053] The obtained adhesive was applied to the surface of the plate at a coating rate of 350 g / m 2 The coating rate was applied to the fir plywood with a water content of 12.4±0.4% after sanding with sandpaper, and the veneer was assembled along the fiber longitudinal direction after gluing. The flat vulcanizing machine was used to cold press at a pressure of 1 MPa for 6 h, and then the glued wood was taken out.

[0054] The preparation steps of the synthetic polyurethane are as follows:

[0055] The polyether polyol C3050 (PEO, 61 g, 0.02 mol) and polyether amine D2000 (PEA, 40 g, 0.02 mol) were placed in a three-necked flask and placed in a 100°C vacuum oven for 1.5 h. Then isophorone diisocyanate (IPDI, 22.2 g, 0.1 mol) was added, and dibutyltin dilaurate (DBTDL, 0.32 g, 0.0005 mol) was added as a catalyst, and the reaction was carried out in an 80°C oil bath for 3 h to obtain a prepolymer. Then glycerol carbonate (GC, 11.8 g, 0.1 mol) was added for end capping reaction for 4 h, and the whole synthesis process was carried out under nitrogen protection. The reaction was confirmed to be complete by the disappearance of the NCO absorption peak (2271 cm -1 ) in the Fourier transform infrared spectrum, and the final reaction obtained the synthetic polyurethane.

[0056] Example 4

[0057] 2 g of the synthetic polyurethane was mixed with 8 g of bisphenol A diglycidyl ether of type E51, then 3.5 g of phenolic amine curing agent was uniformly dispersed, then uniformly stirred at high speed to obtain a polyurethane modified room temperature curing epoxy resin adhesive as shown in Figure 2 .

[0058] The fir plywood with a water content of 12.4±0.4% after sanding with sandpaper was coated with a hydroxymethylated resorcinol primer (HMR solution) at a coating rate of 80 g / m², and dried in a 30°C oven for 2 h. Then 2 g of the synthetic polyurethane was mixed with 8 g of bisphenol A diglycidyl ether of type E51, then 3.5 g of phenolic amine curing agent was added, and homogenously stirred at 2000 rpm for 2 min. The obtained adhesive was applied to the surface of the plate at a coating rate of 350 g / m 2 , and the veneer was assembled along the fiber longitudinal direction after gluing. The flat vulcanizing machine was used to cold press at a pressure of 1 MPa for 6 h, and then the glued wood was taken out.

[0059] The preparation steps of the synthetic polyurethane are as follows:

[0060] Polyether polyol C3050 (PEO, 61 g, 0.02 mol) and polyether amine D2000 (PEA, 40 g, 0.02 mol) were placed in a three-necked flask and placed in a 100°C vacuum oven for 1.5 h. Then isophorone diisocyanate (IPDI, 22.2 g, 0.1 mol) was added, and dibutyltin dilaurate (DBTDL, 0.32 g, 0.0005 mol) was added as a catalyst, and the reaction was carried out in an 80°C oil bath for 3 h to obtain a prepolymer. Then glycerol carbonate (GC, 11.8 g, 0.1 mol) was added for end capping reaction for 4 h, and the whole synthesis process was carried out under nitrogen protection. The reaction was confirmed to be complete by the disappearance of the NCO absorption peak (2271 cm -1 ) in the Fourier transform infrared spectrum, and the final reaction obtained the synthetic polyurethane as shown in Figure 1 .

[0061] Comparative Example 1

[0062] 10 g of bisphenol A diglycidyl ether of type E51 was mixed, then 3.5 g of phenolic amine curing agent was added, and then high-speed stirring was carried out to obtain an adhesive.

[0063] The obtained adhesive was applied to a Chinese fir plywood with a moisture content of 12.4±0.4% after sanding by single-sided coating method at a coating rate of 350 g / m 2 . After gluing, the single board was assembled along the fiber longitudinal direction, and the glued wood was taken out after cold pressing at 1 MPa pressure for 6 h using a flat press.

[0064] The modified epoxy resin adhesives prepared in Comparative Example 1 and Examples 1-4 of the present application were tested for performance as follows:

[0065] The adhesive performance evaluation experiment used Chinese fir plywood, and the two-layer glued wood preparation process parameters were: adhesive application amount 350 g / m 2 . Then it was sent into a flat press, cold pressed at a unit pressure of 1.0 MPa at room temperature for 6 h, and the test piece was taken out after cold pressing and placed at room temperature for three days before being tested for adhesive layer shear strength and immersion peeling. The size of the adhesive layer shear strength sample was prepared according to GB / 26899-2022: 50 mm x 60 mm, and the adhesive application area was 50 mm x 50 mm. The adhesive layer shear strength was tested on a universal mechanical testing machine, with 5 samples per group and the average value was taken.

[0066] The dip and peel test was performed according to the Chinese standard GB / T 26899-2022. The size of the dip and peel sample was 50 mm x 50 mm, and the size of the glue line was 50 mm x 50 mm. Six samples were taken for each group, and the average value was taken. Two test conditions were set: cold water soaking and boiling water soaking. In the cold water dip and peel test, the sample was completely immersed in 25°C water for 24 hours, and then dried in a 70°C oven until the mass recovered to 95%-100% of the original value. After one more cycle, the peel rate was calculated. In the boiling water peel test, the sample was first immersed in boiling water for 4 hours, then transferred to 25°C water for 1 hour, and finally dried in a 70°C oven until the mass recovered to 95%-100% of the original value. After one more cycle, the peel rate was calculated. After the test, the glue line opening length of each adhesive line at both ends of the sample was measured. The total peel rate was the total length of the glue line opening divided by the total length of the glue line at both ends. The maximum single glue line peel rate was the maximum glue line opening length of a single end face divided by the total length of the glue line of the end face. According to the GB / T 26899-2022 standard, the total peel rate should not exceed 5%, and the maximum peel rate should be less than or equal to 25%. The test results are shown in Table 1.

[0067] Table 1 - Glue line strength and dip and peel rate of the sample

[0068] Test sample Peeling of adhesive line Shear strength (unit: MPa) Wood failure rate (unit: %) Total peeling rate in boiling water immersion (unit: %) Maximum peeling rate in boiling water immersion (unit: %) Total peeling rate in cold water immersion (unit: %) Maximum peeling rate in cold water immersion (unit: %) Comparative Example 1 Significant peeling 6.44 59 56.89 49.91 24.41 29.92 Example 1 Peeling 5.42 81 4.70 6.75 7.51 8.21 Example 2 Small amount of peeling 5.86 95.4 4.47 7.20 7.27 9.28 Example 3 Peeling 4.24 72 4.88 6.70 43.89 45.59 Example 4 No peeling 7.10 92 3.75 6.95 4.81 8.09

[0069] Compared with Comparative Example 1, the glue line strength of the test piece of Example 4 was 7.1 MPa, which was 14.91% higher than that of Comparative Example 1. In terms of wood failure rate, the wood failure rate of the test piece of Example 4 was 92%, which was 55.93% higher than that of Comparative Example 1, as shown in Table 1. Figure 3

[0070] Compared with Comparative Example 1, the total peel rate of the sample of Example 3 under boiling water conditions decreased from 56.89% to 4.47%, and the maximum peel rate decreased from 49.91% to 7.2%. In the cold water test, the total peel rate decreased from 24.41% to 7.27%, and the maximum peel rate decreased from 29.92% to 9.28%. The total peel rate of the sample bonded with Example 4 in the boiling water peel test decreased from 4.47% to 3.75%, and the maximum peel rate decreased from 7.2% to 6.95%. In the cold water test, the total peel rate further decreased from 7.27% to 4.81%, and the maximum peel rate decreased from 9.28% to 8.09%, which met the requirements of the national standard GB / T 26899-2022. The results showed that the glue line of the glued wood formed by Example 4 did not crack significantly, indicating that the toughening effect of the synthetic polyurethane on the epoxy resin adhesive was significant, and the toughened glue layer achieved effective stress dissipation, as shown in Figure 4 and Figure 5 ​The blue fluorescence generated under the irradiation of 365 nm ultraviolet light can clearly show the missing glue condition of different areas on the veneer, as shown in FIG. 2. In addition, the polyurethane modified epoxy resin adhesive prepared in Example 2 still has fluorescence effect in liquid state, as shown in FIG. 3. Figure 6 The blue fluorescence generated under the irradiation of 365 nm ultraviolet light can clearly show the missing glue condition of different areas on the veneer, as shown in FIG. 2. In addition, the polyurethane modified epoxy resin adhesive prepared in Example 2 still has fluorescence effect in liquid state, as shown in FIG. 3. Figure 7

[0071] Although the present application has been described with reference to the embodiments above, various improvements can be made thereto and components thereof can be substituted with equivalents without departing from the scope of the present application. In particular, features in the embodiments disclosed herein can be combined with each other in any manner as long as there is no structural conflict, and the combinations are not exhaustively described herein only for the purpose of omitting the length and saving resources. Therefore, the present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.​

Claims

1. A polyurethane-modified epoxy resin adhesive, characterized by, The E51 type bisphenol A diglycidyl ether, the phenolic amine T31 curing agent and the synthetic polyurethane are mixed in a mass ratio of 7-10:3.5:1-3.

2. The polyurethane-modified epoxy resin adhesive according to claim 1, characterized in that, The synthetic polyurethane is prepared from a polyether triol, a polyether amine, isophorone diisocyanate and glycerol carbonate.

3. The polyurethane-modified epoxy resin adhesive according to claim 1, characterized in that, The ratio of the E51 type bisphenol A diglycidyl ether to the synthetic polyurethane is 8:

2.

4. A process for the preparation of a polyurethane-modified epoxy resin adhesive, characterized in that The steps are as follows: S1. The E51 type bisphenol A diglycidyl ether, the phenolic amine T31 curing agent and the synthetic polyurethane are mixed in a mass ratio of 7-10:3.5:1-3. S2. The synthetic polyurethane is added to the E51 type bisphenol A diglycidyl ether. S3. The phenolic amine T31 curing agent is uniformly dispersed in the synthetic polyurethane and the bisphenol A diglycidyl ether obtained in step S2, and then uniformly stirred at high speed to obtain a polyurethane modified room temperature curing epoxy resin adhesive.

5. The method for preparing a polyurethane-modified epoxy resin adhesive according to claim 4, characterized in that, The preparation steps of the synthetic polyurethane are as follows: 61g, 0.02mol of the polyether triol and 40g, 0.02mol of the polyether amine D2000 are placed in a three-necked flask and placed in a 100℃ vacuum oven for 1.5h; Then 22.2g, 0.1mol of isophorone diisocyanate is added, and a few drops of catalyst are added to stir and react at 80℃ for 3h to obtain a prepolymer. Subsequently, 11.8 g, 0.1 mol of glycerol carbonate was added to perform end group capping reaction for 4 h, and the entire synthesis was performed under nitrogen protection. The reaction was confirmed to be completed by disappearance of NCO absorption peak at 2271 cm -1 in Fourier transform infrared spectrum, and the obtained product was a synthesized polyurethane.

6. The method for preparing a polyurethane-modified epoxy resin adhesive according to claim 4, characterized in that, The catalyst is dibutyl tin dilaurate, and the amount is 0.1%-0.5% of the total mass of the raw materials.

7. Use of a polyurethane-modified epoxy resin adhesive prepared according to the process of any one of claims 4 to 6 for improving the resistance to hot-water immersion of glued wood, characterized in that The hydroxymethylated resorcinol primer is coated on the surface of the wood board at a coating rate of 70-90g / m², and after drying, the polyurethane modified epoxy resin adhesive is coated at a coating rate of 300-400g / ², and after assembly along the fiber direction, cold pressing is carried out at a pressure of 0.8-1.2MPa for 5-7h.

8. Use of the polyurethane-modified epoxy resin adhesive according to claim 7 for improving the resistance to hot-water immersion of glued wood, characterized in that, The preparation steps of the hydroxymethylated resorcinol primer are as follows: In the first stage, 361.72g of deionized water and 13.36g of resorcinol are uniformly mixed, and then 9.76g of sodium hydroxide solution is added; First, 3.8g of formaldehyde solution is added, and at the same time, 2g of sodium dodecyl sulfate salt is added, and the reaction is carried out at 25℃ for 2h, and then placed for 24h; In the second stage, 50g of the solution after the completion of the reaction in the first stage is selected, 1.46g of formaldehyde solution is added, and after activation at 25℃ for 1h, it is used.

9. Use of the polyurethane-modified epoxy resin adhesive according to claim 8 for improving the resistance to hot-water immersion of glued wood, characterized in that, The mass fraction of the sodium hydroxide solution is 10.8%.

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