A waterborne polyurethane resin adhesive and its preparation method

Abstract

This invention relates to the field of adhesives and discloses a waterborne polyurethane resin adhesive and its preparation method. The waterborne polyurethane resin adhesive comprises: modified waterborne polyurethane, modified nano-silica, and additives. The modified waterborne polyurethane is prepared by reacting 2-(2'-hydroxy-5'-methylphenyl)benzotriazole and 2,4-dihydroxybenzaldehyde with diphenyldichlorosilane, reacting the obtained silicon-containing additive with ethanolamine to obtain a Schiff base derivative, and then preparing a chain extender modifier with copper ions as the ligand and introducing it into the polyurethane. The modified nano-silica is prepared by modifying with a modified silane coupling agent. The modified silane coupling agent is prepared by reacting p-phenylenediamine and methyl acrylate, and then further substituting with p-phenylenediamine. The resulting aminated nitrogen-containing intermediate is reacted with 3-chloropropyltrimethoxysilane. The adhesive prepared by this invention has excellent tensile strength, resistance to damp heat and ultraviolet aging, flame retardancy, and antibacterial properties.

Description

Technical Field

[0001] This invention belongs to the field of adhesive technology, specifically relating to a water-based polyurethane resin adhesive and its preparation method. Background Technology

[0002] Waterborne polyurethane has advantages such as being environmentally friendly, non-toxic, wear-resistant, and flexible at low temperatures, and is widely used in adhesives and other fields. However, waterborne polyurethane is highly flammable, which can lead to severe dripping and fire spread. Furthermore, the toxic gases produced during combustion can cause asphyxiation or even death to people trapped in a fire. Patent application CN201911052237.3 discloses a two-component polyurethane adhesive, its preparation method, and its application. This two-component polyurethane adhesive contains 20-40 parts by weight of flame-retardant inorganic filler, wherein the flame-retardant inorganic filler is one or more of aluminum hydroxide, magnesium hydroxide, and antimony trioxide, thereby achieving the flame-retardant effect of the polyurethane adhesive. However, inorganic fillers are prone to agglomeration and have poor compatibility with the matrix material. Adding large amounts of flame-retardant inorganic fillers inevitably affects the mechanical properties of the matrix material. In addition, simple physical mixing easily leads to the precipitation of flame-retardant inorganic fillers. Furthermore, when waterborne polyurethane is used in the adhesive field, it is often aged by ultraviolet light or humid heat environments due to long-term exposure to sunlight or external environments, thus damaging its overall performance. Furthermore, bacteria attached to the surface of water-based polyurethane materials may cause cross-infection, thereby threatening human health. Summary of the Invention

[0003] To address the shortcomings mentioned in the background art, the present invention aims to provide a waterborne polyurethane resin adhesive and its preparation method. By adding modified waterborne polyurethane and modified nano-silica, the adhesive is endowed with excellent tensile strength, resistance to damp heat aging and ultraviolet aging, flame retardancy and antibacterial properties.

[0004] The objective of this invention can be achieved through the following technical solutions:

[0005] A waterborne polyurethane resin adhesive comprises the following components in parts by weight: 100 parts modified waterborne polyurethane, 10-20 parts modified nano-silica, 4-10 parts curing agent, 0.01-0.1 parts dispersant, 0.1-0.5 parts defoamer, and 2-5 parts thickener; wherein the curing agent is a hexamethylene diisocyanate trimer; the dispersant is one of BYK-190 and BYK-191; the defoamer is one or a combination of BYK-019, BYK-028, and BYK-022; and the thickener is one or a combination of RM-8W, sodium carboxymethyl cellulose, and polyacrylamide.

[0006] The modified waterborne polyurethane is prepared by simultaneously reacting 2-(2'-hydroxy-5'-methylphenyl)benzotriazole and 2,4-dihydroxybenzaldehyde with diphenyldichlorosilane in a substitution reaction, and then reacting the prepared silicon-containing additive with ethanolamine in a Schiff base reaction to obtain a Schiff base derivative. Subsequently, a chain extender is prepared with copper ions as the central ion and the Schiff base derivative as the ligand, and the chain extender is introduced into the waterborne polyurethane molecular chain.

[0007] The modified nano-silica is prepared by grafting a modified silane coupling agent onto the surface of nano-silica; the modified silane coupling agent is prepared by Michael addition reaction of p-phenylenediamine and methyl acrylate, followed by substitution reaction of the prepared nitrogen-containing intermediate with p-phenylenediamine to prepare an aminated nitrogen-containing intermediate, and then substitution reaction of the aminated nitrogen-containing intermediate with 3-chloropropyltrimethoxysilane.

[0008] Preferably, the preparation method of the modified waterborne polyurethane includes the following steps: polyethylene glycol 2000, 2,2-dimethylolpropionic acid, isophorone diisocyanate and dibutyltin dilaurate are placed in a reactor, the reaction mixture is heated at 70-80°C and stirred under a nitrogen atmosphere for 2-3 hours, then the temperature is raised to 85-90°C, 1,4-butanediol and chain extender are added, and the reaction is continued until the -NCO content in the system reaches the theoretical value. During the reaction, acetone is added to reduce the viscosity of the system. Then the reaction mixture is cooled to 45-50°C, triethylamine is added to neutralize for 25-35 minutes, then deionized water is added under stirring, and finally the residual solvent is removed by rotary evaporation to prepare the modified waterborne polyurethane.

[0009] Preferably, the molar ratio of polyethylene glycol 2000, 2,2-dimethylolpropionic acid, isophorone diisocyanate, 1,4-butanediol, chain extender and triethylamine is 1.5:2.1:8.6:1.2~2.4:0.4~1.6:2.1.

[0010] Preferably, the chain extender modifier has the following structural formula:

[0011] ;

[0012] Its preparation method includes the following steps:

[0013] A. Take 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2,4-dihydroxybenzaldehyde and triethylamine in a reactor, add diphenyldichlorosilane and tetrahydrofuran, and stir the reaction at 70~80℃ for 4~5h. After the reaction is completed, filter, wash and dry to prepare silicon-containing additive.

[0014] B. Take the silicon-containing additive and ethanolamine into a reactor, add methanol solvent, stir the reaction at 55~70℃ for 4~5h, cool to room temperature after the reaction is completed, remove the solvent by rotary evaporation, and prepare Schiff base derivatives.

[0015] C. Take Schiff base derivative and methanol solvent in a reactor, stir and mix, then add a mixed solution of copper acetate and methanol, and stir the reaction at 55~70℃ for 3~5h. After the reaction is completed, cool to room temperature, remove the solvent by rotary evaporation, and wash, filter and recrystallize the solid product to prepare the chain extender modifier.

[0016] Preferably, in step A, the molar ratio of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2,4-dihydroxybenzaldehyde, and diphenyldichlorosilane is 1~1.1:1~1.1:1.

[0017] Preferably, in step B, the molar ratio of silicon-containing additive to ethanolamine is 1:1 to 1.2; and in step C, the molar ratio of Schiff base derivative to copper acetate is 2 to 2.1:1.

[0018] Preferably, the method for preparing the modified nano-silica includes the following steps:

[0019] (1) Take the aminated nitrogen-containing intermediate and N,N-dimethylformamide in a reactor, then add 3-chloropropyltrimethoxysilane, and then add triethylamine as an acid-binding agent. Stir the reaction at 70~85℃ for 6~8h under a nitrogen atmosphere. After the reaction is completed, filter, wash and dry to prepare the modified silane coupling agent.

[0020] (2) Take nano-silica and ultrasonically disperse it in a mixed solution of anhydrous ethanol and deionized water. Then add modified silane coupling agent and stir at 60~85℃ for 4~7h. After the reaction is completed, filter, wash and dry to prepare modified nano-silica.

[0021] Preferably, the structural formula of the amination nitrogen-containing intermediate is:

[0022] ;

[0023] Its preparation method includes the following steps:

[0024] ① Take p-phenylenediamine and methanol in a reactor, place them in an ice-water bath and under nitrogen protection, add methyl acrylic acid and react for 2-3 hours, then raise the temperature to 20-25℃ and continue stirring for 45-48 hours. After the reaction is completed, use a rotary evaporator to perform rotary evaporation to prepare a nitrogen-containing intermediate.

[0025] ② Take p-phenylenediamine and methanol in a reactor, place them under an ice-water bath and nitrogen protection, add a mixed solution of nitrogen-containing intermediate and methanol, stir and react for 2-3 hours, then raise the temperature to 20-25℃ and continue stirring and reacting for 68-72 hours. After the reaction is completed, use a rotary evaporator to perform rotary evaporation to prepare the aminated nitrogen-containing intermediate.

[0026] A method for preparing a waterborne polyurethane resin adhesive includes the following steps:

[0027] S1. Weigh each component according to the weight parts, and stir and mix the modified waterborne polyurethane, modified nano silica, dispersant and thickener evenly to obtain a premix.

[0028] S2. Add curing agent and defoamer to the premix, and continue stirring and mixing to prepare waterborne polyurethane resin adhesive.

[0029] The beneficial effects of this invention are:

[0030] This invention utilizes the substitution reaction between the hydroxyl groups in 2-(2'-hydroxy-5'-methylphenyl)benzotriazole and the chlorine atoms at both ends of diphenyldichlorosilane to prepare a silicon-containing additive. Then, the aldehyde group in the silicon-containing additive undergoes a Schiff base reaction with the amino group in ethanolamine to prepare a Schiff base derivative. Finally, using copper ions as the central ion and the Schiff base derivative as the ligand, a chain extender modifier containing two hydroxyl groups is prepared and introduced into the molecular chain of waterborne polyurethane. This chain extender modifier introduces an antibacterial Schiff base group, a silicon-oxygen bond with good heat and water resistance, a benzotriazole group with UV absorption, and copper ions with good antibacterial and flame retardant properties, thereby endowing the adhesive with excellent heat and water resistance, antibacterial properties, UV aging resistance, and flame retardant properties.

[0031] This invention utilizes the Michael addition reaction between the amino groups at both ends of p-phenylenediamine and the double bond in methyl acrylate to prepare a nitrogen-containing intermediate. Then, the methoxy group in the nitrogen-containing intermediate undergoes a substitution reaction with the amino group at one end of p-phenylenediamine to prepare an aminated nitrogen-containing intermediate. Subsequently, the amino group in the aminated nitrogen-containing intermediate undergoes a substitution reaction with the chlorine atom in 3-chloropropyltrimethoxysilane to prepare a modified silane coupling agent. Finally, the silanol groups in the modified silane coupling agent undergo dehydration condensation with the hydroxyl groups on the surface of nano-silica to prepare modified nano-silica. This allows the anti-aging agent p-phenylenediamine to be firmly bonded to the surface of nano-silica through chemical bonds, introducing anti-aging functional groups and endowing the adhesive with long-term high-temperature aging resistance. Furthermore, the grafting reaction enhances the oleophilicity of the nano-silica surface, promoting the relatively uniform dispersion of nano-silica in the matrix material, which is beneficial to the full utilization of the mechanical properties of nano-silica. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 These are comparative infrared spectra of the Schiff base derivative and the chain extender prepared in Example 1 of this invention;

[0034] Figure 2 These are comparative infrared spectra of the aminated nitrogen-containing intermediate, the modified silane coupling agent, and 3-chloropropyltrimethoxysilane prepared in Example 2 of this invention. Detailed Implementation

[0035] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0036] Example 1: A method for preparing a modified waterborne polyurethane includes the following steps:

[0037] 0.015 mol polyethylene glycol 2000, 0.021 mol 2,2-dimethylolpropionic acid, 0.086 mol isophorone diisocyanate, and 0.3 wt% dibutyltin dilaurate were placed in a reactor. The reaction mixture was heated at 80 °C and stirred under a nitrogen atmosphere for 2 h. Then, the temperature was raised to 90 °C, and 0.020 mol 1,4-butanediol and 0.008 mol chain extender were added. The reaction mixture was reacted for 1.5 h. During the reaction, a small amount of acetone was added to reduce the viscosity of the system. The reaction mixture was then cooled to 50 °C, and 0.021 mol triethylamine was added to neutralize it for 30 min. Deionized water was then added under stirring. Finally, the residual solvent was removed by rotary evaporation to prepare a modified waterborne polyurethane with a solid content of 45%.

[0038] The preparation method of the chain extender modifier includes the following steps:

[0039] A. Take 4.6g of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2.8g of 2,4-dihydroxybenzaldehyde and 4.1g of triethylamine into a reactor, add 5.1g of diphenyldichlorosilane and 50mL of tetrahydrofuran, and stir the mixture at 80℃ for 4h. After the reaction is completed, filter, wash and dry to prepare a silicon-containing additive.

[0040] B. Take 10.8g of silicon-containing additive (Mr=543.6) and 1.3g of ethanolamine into a reactor, add 50mL of methanol solvent, stir and react at 60℃ for 5h, after the reaction is completed, cool to room temperature, remove the solvent by rotary evaporation, and prepare Schiff base derivatives.

[0041] C. Take 5.9g of Schiff base derivative (Mr=586.7) and 50mL of methanol solvent in a reactor, stir and mix, then add a mixed solution of 0.9g of copper acetate and 25mL of methanol, and stir the reaction at 60℃ for 4h. After the reaction is completed, cool to room temperature, remove the solvent by rotary evaporation, and wash, filter and recrystallize the solid product to prepare the chain extender modifier.

[0042] from Figure 1 As can be seen from the spectrum, the Schiff base derivative spectrum is at 1443 cm⁻¹ -1 and 1599cm -1 Stretching vibration peaks of -CN and -C=C appear at benzotriazole compounds, but ethanolamine does not show peaks at 3400 cm⁻¹. -1 The left and right sides show a double peak of νs-NH2, and νs-C=N is at 1651 cm⁻¹. -1 The formation at this point signifies the successful synthesis of the Schiff base structure, and the νs-C=N in the chain extender exhibits a slight red shift to 1635 cm⁻¹. -1 The position at 3328 cm⁻¹ is likely due to the coordination of the nitrogen atom in the C=N bond with the copper ion. -1 The νs-OH at 3245 cm⁻¹ represents the phenolic and alcoholic hydroxyl groups in the Schiff base derivative. -1 The νs-OH at the position is the alcohol hydroxyl group in the chain extender. The reason why the intensity of the hydroxyl peak of the chain extender is weakened is because the phenolic hydroxyl group participates in coordination, indicating that the chain extender was successfully synthesized.

[0043] Example 2: A method for preparing a modified waterborne polyurethane includes the following steps:

[0044] 0.015 mol polyethylene glycol 2000, 0.021 mol 2,2-dimethylolpropionic acid, 0.086 mol isophorone diisocyanate and 0.3 wt% dibutyltin dilaurate were placed in a reactor. The reaction mixture was heated at 70 °C and stirred under a nitrogen atmosphere for 3 h. Then, the temperature was raised to 85 °C, and 0.013 mol 1,4-butanediol and 0.012 mol chain extender were added and reacted for 2 h. During the reaction, a small amount of acetone was added to reduce the viscosity of the system. Then, the reaction mixture was cooled to 50 °C, and 0.021 mol triethylamine was added to neutralize for 30 min. Then, deionized water was added under stirring. Finally, the residual solvent was removed by rotary evaporation to prepare a modified waterborne polyurethane with a solid content of 45%.

[0045] The preparation method of the chain extender modifier includes the following steps:

[0046] A. Take 4.6g of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2.8g of 2,4-dihydroxybenzaldehyde and 4.1g of triethylamine into a reactor, add 5.1g of diphenyldichlorosilane and 50mL of tetrahydrofuran, and stir the mixture at 80℃ for 4h. After the reaction is completed, filter, wash and dry to prepare a silicon-containing additive.

[0047] B. Take 10.8g of silicon-containing additive (Mr=543.6) and 1.3g of ethanolamine into a reactor, add 50mL of methanol solvent, stir and react at 60℃ for 5h, after the reaction is completed, cool to room temperature, remove the solvent by rotary evaporation, and prepare Schiff base derivatives.

[0048] C. Take 5.9g of Schiff base derivative (Mr=586.7) and 50mL of methanol solvent in a reactor, stir and mix, then add a mixed solution of 0.9g of copper acetate and 25mL of methanol, and stir the reaction at 60℃ for 4h. After the reaction is completed, cool to room temperature, remove the solvent by rotary evaporation, and wash, filter and recrystallize the solid product to prepare the chain extender modifier.

[0049] Example 3 A method for preparing modified nano-silica includes the following steps:

[0050] (1) Take 11g of aminated nitrogen-containing intermediate and 50mL of N,N-dimethylformamide in a reactor, then add 10g of 3-chloropropyltrimethoxysilane, and then add 10mL of triethylamine as an acid-binding agent. Stir and react at 80°C for 8h under a nitrogen atmosphere. After the reaction is completed, filter, wash and dry to prepare the modified silane coupling agent.

[0051] (2) Take 5g of nano silica and ultrasonically disperse it in a mixed solution of 90mL anhydrous ethanol and 10mL deionized water. Then add 3.6g of modified silane coupling agent and stir at 70℃ for 5h. After the reaction is completed, filter, wash and dry to prepare modified nano silica.

[0052] The preparation method of the amination nitrogen-containing intermediate includes the following steps:

[0053] ① Take 9g of p-phenylenediamine and 20mL of methanol in a reactor, place it in an ice-water bath and under nitrogen protection, add 35g of methyl acrylate and react for 2.5h, then raise the temperature to 20℃ and continue stirring for 48h. After the reaction is completed, use a rotary evaporator to perform rotary evaporation to prepare a nitrogen-containing intermediate.

[0054] ② Take 37.4g of p-phenylenediamine and 60mL of methanol in a reactor, place it in an ice-water bath and under nitrogen protection, add 28g of nitrogen-containing intermediate and 60mL of methanol mixed solution, stir and react for 2.5h, then raise the temperature to 20℃ and continue stirring and reacting for 72h. After the reaction is completed, use a rotary evaporator to perform rotary evaporation to prepare the aminated nitrogen-containing intermediate.

[0055] from Figure 2 As can be seen from the spectrum of the modified silane coupling agent, the 3400 cm⁻¹ value is... -1 The broad peak at 1640 cm⁻¹ is the asymmetric stretching vibration band of -NH₂. -1 The peak at 1550 cm⁻¹ is a typical absorption peak for the C=O group in amides. -1 The area is a coupling zone between -NH bending and -CN stretching, 2938cm. -1 and 2934cm -1 The peaks at 1080 cm⁻¹ represent the symmetric and asymmetric stretching vibrations of -CH₂. -1 The peak at this point is a characteristic absorption peak of the siloxane bond, indicating the successful synthesis of the modified silane coupling agent.

[0056] Example 4 A waterborne polyurethane resin adhesive comprising the following components by weight: 100 parts of modified waterborne polyurethane prepared in Example 1, 12 parts of modified nano silica prepared in Example 2, 4.5 parts of curing agent Desmodur DN, 0.02 parts of dispersant BYK-190, 0.1 parts of defoamer BYK-019, and 2 parts of thickener RM-8W.

[0057] The preparation method of the above-mentioned waterborne polyurethane resin adhesive includes the following steps:

[0058] S1. Weigh each component according to the weight parts, and stir and mix the modified waterborne polyurethane, modified nano silica, dispersant and thickener evenly to obtain a premix.

[0059] S2. Add curing agent and defoamer to the premix, and continue stirring and mixing to prepare waterborne polyurethane resin adhesive.

[0060] Example 5 A waterborne polyurethane resin adhesive comprising the following components by weight: 100 parts of modified waterborne polyurethane prepared in Example 1, 15 parts of modified nano silica prepared in Example 2, 7 parts of curing agent Desmodur DN, 0.04 parts of dispersant BYK-190, 0.3 parts of defoamer BYK-019, and 3.5 parts of thickener RM-8W.

[0061] The preparation method of the above-mentioned waterborne polyurethane resin adhesive is the same as that in Example 4.

[0062] Example 6 A waterborne polyurethane resin adhesive comprising the following components by weight: 100 parts of modified waterborne polyurethane prepared in Example 1, 18 parts of modified nano silica prepared in Example 2, 9 parts of curing agent Desmodur DN, 0.06 parts of dispersant BYK-190, 0.4 parts of defoamer BYK-019, and 4.5 parts of thickener RM-8W.

[0063] The preparation method of the above-mentioned waterborne polyurethane resin adhesive is the same as that in Example 4.

[0064] Example 7 A waterborne polyurethane resin adhesive comprising the following components by weight: 100 parts of modified waterborne polyurethane prepared in Example 2, 18 parts of modified nano silica prepared in Example 2, 9 parts of curing agent Desmodur DN, 0.06 parts of dispersant BYK-190, 0.4 parts of defoamer BYK-019, and 4.5 parts of thickener RM-8W.

[0065] The preparation method of the above-mentioned waterborne polyurethane resin adhesive is the same as that in Example 4.

[0066] Comparative Example 1: A method for preparing modified waterborne polyurethane. Compared with Example 1, the chain extender in Example 1 is replaced in equimolar form with the Schiff base derivative prepared in Example 1, and the remaining components and preparation method are the same as in Example 1.

[0067] Comparative Example 2: A method for preparing a modified waterborne polyurethane. Compared with Example 1, the chain extender modifier in Example 1 was replaced with 1,4-butanediol in equal molar amounts, while the remaining components and preparation method were the same as in Example 1.

[0068] Comparative Example 3: A waterborne polyurethane resin adhesive comprising the following components by weight: 100 parts of modified waterborne polyurethane prepared in Comparative Example 1, 18 parts of modified nano silica prepared in Example 2, 9 parts of curing agent Desmodur DN, 0.06 parts of dispersant BYK-190, 0.4 parts of defoamer BYK-019, and 4.5 parts of thickener RM-8W.

[0069] The preparation method of the above-mentioned waterborne polyurethane resin adhesive is the same as that in Example 3.

[0070] Comparative Example 4: A waterborne polyurethane resin adhesive comprising the following components in parts by weight: 100 parts of modified waterborne polyurethane prepared in Comparative Example 2, 18 parts of modified nano-silica prepared in Example 2, 9 parts of curing agent Desmodur DN, 0.06 parts of dispersant BYK-190, 0.4 parts of defoamer BYK-019, and 4.5 parts of thickener RM-8W.

[0071] The preparation method of the above-mentioned waterborne polyurethane resin adhesive is the same as that in Example 3.

[0072] Comparative Example 5: A waterborne polyurethane resin adhesive comprising the following components by weight: 100 parts of modified waterborne polyurethane prepared in Example 1, 18 parts of nano silica, 9 parts of curing agent Desmodur DN, 0.06 parts of dispersant BYK-190, 0.4 parts of defoamer BYK-019, and 4.5 parts of thickener RM-8W.

[0073] The preparation method of the above-mentioned waterborne polyurethane resin adhesive is the same as that in Example 3.

[0074] Performance testing

[0075] The aqueous polyurethane resin adhesives prepared in Examples 4-7 and Comparative Examples 3-5 were poured into a polytetrafluoroethylene plate, dried to form a film, and then removed for performance testing.

[0076] (1) Take a PVC (2.5cm×25cm) and a 0.5cm thick wooden board, apply adhesive, heat in a 60℃ oven for 5min, bond, press with a 10kg weight for 1min, and use a universal tensile testing machine to measure the initial tack and tensile strength within 10min; place the sample in an HJ / CQ-80H constant temperature and humidity chamber, control the relative humidity and temperature to 80% and 80℃ respectively, and test the tensile strength after 7d of damp heat aging to evaluate the sample’s resistance to damp heat aging; place the sample in an aging chamber, and test the tensile strength after 10h of UV aging under a 1000W mercury lamp to evaluate the sample’s resistance to UV aging. The data results are shown in Table 1.

[0077] (2) Limiting oxygen index test: The film was made into a size of 100mm×6.5mm×3mm according to ASTM D2863 and the test results are shown in Table 1.

[0078] (3) Vertical burning test: The film was made into a size of 100mm×12.7mm×3mm according to GB / T 2408-2021 and the test was carried out. The data results are shown in Table 1.

[0079] (4) Antibacterial performance test: The antibacterial effect of the sample against Escherichia coli and Staphylococcus aureus was tested by plate count method. The activated bacterial solution was added to the test tube and diluted until the total bacterial count was 10. 6 The concentration of CFU / mL was increased. The gel film was added to the bacterial solution and placed in a constant temperature incubator. The solution was then shaken and cultured at 37°C for 24 hours. The diluted bacterial solution was then coated onto agar medium and placed in a constant temperature incubator. After culturing at 37°C for 24 hours, the number of colonies in each culture dish was observed. The inhibition rate was calculated using the colony count = (R0-R1) / R0, where R0 is the number of colonies without the gel film and R1 is the number of colonies with the gel film. The data results are shown in Table 1.

[0080] Table 1 Sample performance test results

[0081] ;

[0082] As can be seen from the data results in Table 1, the adhesives prepared in Examples 4-7 of the present invention have high tensile strength and excellent resistance to damp heat aging, UV aging, flame retardancy and antibacterial properties. In Comparative Example 3, the modified waterborne polyurethane component did not contain copper acetate. Its limiting oxygen index, vertical flammability rating, and antibacterial rate were lower than those of Examples 4-7, indicating that the chain extender modifier prepared with copper ions as the central ion and Schiff base derivatives as ligands can improve the flame retardant and antibacterial properties of the adhesive. In Comparative Example 4, no chain extender modifier was added. Its tensile strength, limiting oxygen index, vertical flammability rating, and antibacterial rate after aging were significantly lower than those of Examples 4-7, indicating that the addition of the chain extender modifier greatly improved the adhesive's resistance to damp heat aging, UV aging, flame retardancy, and antibacterial properties to a certain extent. In Comparative Example 5, no nano-silica modification treatment was performed. Its tensile strength and tensile strength after damp heat aging were lower than those of Examples 4-7. This is because the aggregation of nano-silica particles led to a decrease in mechanical properties, and the grafting of the antioxidant with phenylenediamine improved the adhesive's resistance to damp heat aging.

[0083] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0084] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A water-based polyurethane resin adhesive, characterized in that, The product comprises the following components by weight: 100 parts modified waterborne polyurethane, 10-20 parts modified nano-silica, 4-10 parts curing agent, 0.01-0.1 parts dispersant, 0.1-0.5 parts defoamer, and 2-5 parts thickener; wherein the curing agent is a hexamethylene diisocyanate trimer; the dispersant is one of BYK-190 and BYK-191; the defoamer is one or a combination of BYK-019, BYK-028, and BYK-022; and the thickener is one or a combination of RM-8W, sodium carboxymethyl cellulose, and polyacrylamide. The modified waterborne polyurethane is prepared by introducing a chain extender into the waterborne polyurethane molecular chain; The structural formula of the chain extender is: ； Its preparation method includes the following steps: A. Take 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2,4-dihydroxybenzaldehyde and triethylamine in a reactor, add diphenyldichlorosilane and tetrahydrofuran, and stir the reaction at 70~80℃ for 4~5h. After the reaction is completed, filter, wash and dry to prepare silicon-containing additive. B. Take the silicon-containing additive and ethanolamine into a reactor, add methanol solvent, stir the reaction at 55~70℃ for 4~5h, cool to room temperature after the reaction is completed, remove the solvent by rotary evaporation, and prepare Schiff base derivatives. C. Take Schiff base derivative and methanol solvent in a reactor, stir and mix, then add a mixed solution of copper acetate and methanol, and stir the reaction at 55~70℃ for 3~5h. After the reaction is completed, cool to room temperature, remove the solvent by rotary evaporation, and wash, filter and recrystallize the solid product to prepare the chain extender modifier. The modified nano-silica is prepared by grafting a modified silane coupling agent onto the surface of nano-silica; the modified silane coupling agent is prepared by Michael addition reaction of p-phenylenediamine and methyl acrylate, followed by substitution reaction of the prepared nitrogen-containing intermediate with p-phenylenediamine to prepare an aminated nitrogen-containing intermediate, and then substitution reaction of the aminated nitrogen-containing intermediate with 3-chloropropyltrimethoxysilane.

2. The waterborne polyurethane resin adhesive according to claim 1, characterized in that, The preparation method of the modified waterborne polyurethane includes the following steps: polyethylene glycol 2000, 2,2-dimethylolpropionic acid, isophorone diisocyanate and dibutyltin dilaurate are placed in a reactor. The reaction mixture is heated at 70-80°C and stirred under a nitrogen atmosphere for 2-3 hours. Then the temperature is raised to 85-90°C, 1,4-butanediol and chain extender are added, and the reaction is continued until the -NCO content in the system reaches the theoretical value. Acetone is added during the reaction to reduce the viscosity of the system. Then the reaction mixture is cooled to 45-50°C, triethylamine is added for neutralization for 25-35 minutes, deionized water is added under stirring, and finally the residual solvent is removed by rotary evaporation to prepare the modified waterborne polyurethane.

3. The waterborne polyurethane resin adhesive according to claim 2, characterized in that, The molar ratio of polyethylene glycol 2000, 2,2-dimethylolpropionic acid, isophorone diisocyanate, 1,4-butanediol, chain extender and triethylamine is 1.5:2.1:8.6:1.2~2.4:0.4~1.6:2.

1.

4. The waterborne polyurethane resin adhesive according to claim 1, characterized in that, In step A, the molar ratio of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2,4-dihydroxybenzaldehyde, and diphenyldichlorosilane is 1~1.1:1~1.1:

1.

5. The waterborne polyurethane resin adhesive according to claim 1, characterized in that, In step B, the molar ratio of silicon additive to ethanolamine is 1:1 to 1.2; in step C, the molar ratio of Schiff base derivative to copper acetate is 2 to 2.1:

1.

6. The waterborne polyurethane resin adhesive according to claim 1, characterized in that, The method for preparing the modified nano-silica includes the following steps: (1) Take the aminated nitrogen-containing intermediate and N,N-dimethylformamide in a reactor, then add 3-chloropropyltrimethoxysilane, and then add triethylamine as an acid-binding agent. Stir the reaction at 70~85℃ for 6~8h under a nitrogen atmosphere. After the reaction is completed, filter, wash and dry to prepare the modified silane coupling agent. (2) Take nano-silica and ultrasonically disperse it in a mixed solution of anhydrous ethanol and deionized water. Then add modified silane coupling agent and stir at 60~85℃ for 4~7h. After the reaction is completed, filter, wash and dry to prepare modified nano-silica.

7. The waterborne polyurethane resin adhesive according to claim 6, characterized in that, The structural formula of the amination nitrogen-containing intermediate is: ； Its preparation method includes the following steps: ① Take p-phenylenediamine and methanol in a reactor, place them in an ice-water bath and under nitrogen protection, add methyl acrylic acid and react for 2-3 hours, then raise the temperature to 20-25℃ and continue stirring for 45-48 hours. After the reaction is completed, use a rotary evaporator to perform rotary evaporation to prepare a nitrogen-containing intermediate. ② Take p-phenylenediamine and methanol in a reactor, place them under an ice-water bath and nitrogen protection, add a mixed solution of nitrogen-containing intermediate and methanol, stir and react for 2-3 hours, then raise the temperature to 20-25℃ and continue stirring and reacting for 68-72 hours. After the reaction is completed, use a rotary evaporator to perform rotary evaporation to prepare the aminated nitrogen-containing intermediate.

8. A method for preparing an aqueous polyurethane resin adhesive according to any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Weigh each component according to the weight parts, and stir and mix the modified waterborne polyurethane, modified nano silica, dispersant and thickener evenly to obtain a premix. S2. Add curing agent and defoamer to the premix, and continue stirring and mixing to prepare waterborne polyurethane resin adhesive.

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