A polyurethane adhesive composition and a method for preparing the same

Abstract

The application belongs to the technical field of high polymer materials, and particularly relates to a polyurethane adhesive composition and a preparation method thereof, which comprises the following components in parts by weight: polytetrahydrofuran ether glycol 50-55 parts, 6,6'-bis[(3-benzyloxy-1,2-propanediol)oxy]bis(1-hexanol) 8-15 parts, stabilizer 3-5 parts, diisocyanate 35-45 parts, catalyst 0.1-0.5 parts, and defoaming agent 0.8-1.5 parts; the polyurethane adhesive composition of the application, by introducing the stabilizer and 6,6'-bis[(3-benzyloxy-1,2-propanediol)oxy]bis(1-hexanol), and the components in the formula, gives the polyurethane adhesive excellent yellowing resistance, acid and alkali resistance, heat resistance, water resistance and mechanical properties. And the preparation process is relatively simple, does not involve the use of volatile solvents, and is more green and environmentally friendly than the traditional polyurethane adhesive preparation method.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and particularly relates to a polyurethane adhesive composition and its preparation method. Background Technology

[0002] Green adhesives are those that are non-toxic to humans and non-polluting to the environment. Therefore, solvent-free, solid, and low-toxicity adhesives are becoming the main directions for future development. Among them, solvent-free polyurethane adhesives are an environmentally friendly green adhesive with a VOCs emission reduction rate of over 99%. Because they do not contain toxic volatile substances such as toluene and formaldehyde, they have no irritating odor during production and use. They also possess excellent bonding performance, simple production processes, and fast curing speeds, showing a promising development trend. Polyurethane adhesives, in particular, have excellent bonding performance with plastics and rubber, and are widely used in footwear, packaging, automotive, construction, textile, electronics, and wood processing industries.

[0003] Currently, polyurethane adhesives with different properties can be formulated to meet various application needs. However, a significant drawback of current polyurethane adhesives remains: their molecular chains often contain groups susceptible to light exposure, such as alkenyl, carbonyl, and diamino chromophores, as well as methyl and hydroxyl auxochromes. Prolonged exposure to ultraviolet radiation and heat can cause significant yellowing of the material. This yellowing not only severely impairs the aesthetic appearance of bonded products but may also affect the physicochemical properties of the adhesive layer itself, thus impacting the overall performance of the product. Furthermore, existing polyurethane adhesives also exhibit relatively limited heat resistance, water resistance, chemical resistance, and yellowing resistance.

[0004] Therefore, in order to overcome the limitations of existing materials, it is of great significance to develop yellowing-resistant polyurethane adhesives that combine excellent heat resistance, water resistance, chemical resistance and environmental protection properties. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, one of the objectives of this invention is to provide a polyurethane adhesive composition. The polyurethane adhesive composition of this invention, by introducing a stabilizer and 6,6'-bis[(3-benzyloxy-1,2-propanediol)oxy]bis(1-hexanol), works synergistically with the components in the formulation to impart excellent resistance to yellowing, acid and alkali, heat resistance, water resistance, and mechanical properties to the polyurethane adhesive.

[0006] A second objective of this invention is to provide a method for preparing a polyurethane adhesive composition. This preparation process is relatively simple, does not involve the use of volatile solvents, and is more environmentally friendly than traditional polyurethane adhesive preparation methods.

[0007] One of the objectives of this invention is achieved through the following technical solution:

[0008] A polyurethane adhesive composition, by weight, comprises the following components: 50-55 parts of polytetrahydrofuran ether diol, 8-15 parts of 6,6'-bis[(3-benzyloxy-1,2-propanediol)oxy]bis(1-hexanol), 3-5 parts of stabilizer, 35-45 parts of diisocyanate, 0.1-0.5 parts of catalyst, and 0.8-1.5 parts of defoamer; the chemical structural formula of the stabilizer is as follows:

[0009] .

[0010] Furthermore, the preparation process of the stabilizer includes the following steps:

[0011] (1) Difluorobromoacetic acid, 4-aminomethylbenzyl alcohol, triethylamine, and 1H-benzotriazol-1-yloxytripyrrolidinyl hexafluorophosphate were added to a solvent to react, and then compound 1 was obtained by extraction and purification;

[0012] (2) Benzophenone, compound 1, dichlorobis(4-methylisopropylphenyl)ruthenium(II), sodium carbonate, silver trifluoroacetate, N-acetyl-L-isoleucine and tert-butylammonium chloride were added to a solvent under a nitrogen atmosphere and reacted, and then purified to obtain the product.

[0013] Further, in step (1), the molar ratio of difluorobromoacetic acid, 4-aminomethylbenzyl alcohol, triethylamine, and 1H-benzotriazol-1-yloxytripyrrolidinyl hexafluorophosphate is 1:(2.5-3):(2-2.6):(1-1.3), and the ratio of difluorobromoacetic acid to solvent is 1 mol:20-30 mL.

[0014] Further, in step (2), the molar ratio of benzophenone, compound 1, dichlorobis(4-methylisopropylphenyl)ruthenium(II), sodium carbonate, silver trifluoroacetate, N-acetyl-L-isoleucine, and tert-butylammonium chloride is 1:(3-3.3):(0.2-0.3):(2-2.5):(2-2.5):(1.5-2):(0.5-0.8), and the volume ratio of benzophenone to solvent is 1 mol:30-40 mL.

[0015] Further, the reaction time in step (1) is 8-12 h, and the solvent in step (1) is anhydrous N,N-dimethylformamide; the reaction temperature in step (2) is 120-140 °C, and the reaction time is 36-48 h; the solvent in step (2) is dichloroethane.

[0016] Furthermore, the preparation process of 6,6'-bis[(3-benzyloxy-1,2-propanediol)oxy]bis(1-hexanol) includes the following steps:

[0017] a. Add 3-benzyloxy-1,2-propanediol to the solvent, add sodium hydride and stir, cool to room temperature, then add 2-(6-bromohexyloxy)tetrahydropyran to continue the reaction; after the reaction is complete, extract, wash, concentrate and purify the reaction solution to obtain compound 2.

[0018] b. Add compound 2 and p-toluenesulfonic acid to a solvent to react; extract, wash, concentrate and purify the reaction solution to obtain the final product.

[0019] Further, in step a, the molar ratio of 3-benzyloxy-1,2-propanediol, sodium hydride, and 2-(6-bromohexyloxy)tetrahydropyran is 1:(4-5):(2.4-3); the volume ratio of 3-benzyloxy-1,2-propanediol to solvent is 1 mol:8-15 mL; the stirring temperature is 75-85℃ and the time is 30-45 min; the reaction temperature is 75-85℃ and the time is 16-18 h; the solvent is anhydrous N,N-dimethylformamide.

[0020] Further, in step b, the molar ratio of compound 2 to p-toluenesulfonic acid is 1:(1.4-1.6), the reaction time is 16-24 h; the volume ratio of compound 2 to solvent is 1 mol: 40-50 mL; and the solvent is ethanol.

[0021] Further, the number average molecular weight of the polytetrahydrofuran ether diol is 1000-2000; the diisocyanate is hexamethylene diisocyanate or toluene-2,4-diisocyanate; the catalyst is stannous octoate or dibutyltin dilaurate; and the defoamer is BYK-019 or BYK-024.

[0022] The second objective of this invention is achieved by the following technical solution:

[0023] The method for preparing the polyurethane adhesive composition provided by the present invention includes the following steps:

[0024] S1. Heat the diisocyanate to 70-75℃, add the dehydrated polytetrahydrofuran ether diol and react for 45-75 min to obtain the prepolymer;

[0025] S2. Heat the prepolymer obtained in step S1 to 80-85℃, add 6,6'-bis[(3-benzyloxy-1,2-propanediol)oxy]bis(1-hexanol), stabilizer, and catalyst, stir and react for 2-4 hours, then add defoamer and stir for 30-40 minutes to obtain the final product.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] 1. The present invention provides a polyurethane adhesive composition that has excellent resistance to yellowing, acid and alkali, heat resistance, water resistance and mechanical properties.

[0028] (1) The stabilizer of the present invention is modified by synergistic modification of fluorine atoms and benzyl alcohol groups. The fluorine atoms reduce the electron cloud density of the carbonyl group through a strong electronegativity induction effect, which can stabilize its π-π ultraviolet absorption and weaken π-π stacking, thereby inhibiting the yellowing phenomenon caused by photo-oxidation. In addition, the hydroxyl groups of benzyl alcohol are covalently cross-linked with the isocyanate groups (-NCO) of the polyurethane prepolymer, fixing the stabilizer with ultraviolet absorption function in the polyurethane network; at the same time, the fluorine-containing segments in the stabilizer can reduce the surface energy, form a hydrophobic surface, and give the material good water resistance.

[0029] (2) The ether oxygen bond in 6,6'-bis[(3-benzyloxy-1,2-propanediol)oxy]bis(1-hexanol) of the present invention generates a dipole-dipole synergy with the fluorine element in the stabilizer, which improves the rigidity of local chain segments and restricts the chain segment movement at high temperature, thereby delaying the thermal decomposition process. At the same time, the two groups are spatially complementary, which can effectively isolate the penetration of corrosive media and stabilize the skeleton structure of polyurethane adhesive at high temperature. That is, 6,6'-bis[(3-benzyloxy-1,2-propanediol)oxy]bis(1-hexanol) and the stabilizer can work together to improve the acid and alkali resistance and heat resistance of polyurethane.

[0030] 2. This invention provides a method for preparing a polyurethane adhesive composition. The preparation process is relatively simple and does not involve the use of volatile solvents, making it more environmentally friendly than traditional polyurethane adhesive preparation methods. Detailed Implementation

[0031] The present invention will now be further described in conjunction with specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. Specific conditions not specified in the embodiments shall be performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, all reagents or instruments used are conventional products obtained through commercial channels.

[0032] Example 1

[0033] A polyurethane adhesive composition, by weight, comprises the following components: 52 parts of polytetrahydrofuran ether diol (number average molecular weight 2000), 12 parts of 6,6'-bis[(3-benzyloxy-1,2-propanediol)oxy]bis(1-hexanol), 4 parts of stabilizer, 40 parts of diisocyanate (hexamethylene diisocyanate), 0.3 parts of catalyst (stannous octoate), and 1.2 parts of defoamer (BYK-019);

[0034] The preparation process of the stabilizer includes the following steps:

[0035]

[0036] (1) Difluorobromoacetic acid, 4-aminomethylbenzyl alcohol, triethylamine, and 1H-benzotriazol-1-yloxytripyrrolidinyl hexafluorophosphate were added to anhydrous N,N-dimethylformamide and reacted for 10 h; the molar ratio of difluorobromoacetic acid, 4-aminomethylbenzyl alcohol, triethylamine, and 1H-benzotriazol-1-yloxytripyrrolidinyl hexafluorophosphate was 1:2.7:2.5:1.2, and the molar ratio of difluorobromoacetic acid to anhydrous N,N-dimethylformamide was 1 mol:25 mL; then water was added for dilution and extraction with ethyl acetate was performed. The organic layer was washed with saturated brine, dried, and filtered to remove the solvent, and the residue was obtained by column chromatography (V 乙酸乙酯 V 正己烷 The mixture of compounds 1, with a ratio of 30:70, was purified to obtain compound 1; compound 1... 1 The H NMR results are as follows: 1 H NMR (C 10 H 10 BrF2NO2, 400MHz, DMSO-d6) δ 8.63 (s, 1H), 7.25 (dd, 4H), 5.32 (s, 1H), 4.63 (s, 2H), 4.26(s, 2H); HRMS(ESI) calcd for C 10 H 10 BrF₂NO₂[M+H] + 293.99, found 294.00;

[0037] (2) Under a nitrogen atmosphere, benzophenone, compound 1, dichlorobis(4-methylisopropylphenyl)ruthenium(II), sodium carbonate, silver trifluoroacetate, N-acetyl-L-isoleucine, and tert-butylammonium chloride were added to dichloroethane and stirred evenly at room temperature. The mixture was then heated to 130°C and reacted for 40 h. The molar ratio of benzophenone, compound 1, dichlorobis(4-methylisopropylphenyl)ruthenium(II), sodium carbonate, silver trifluoroacetate, N-acetyl-L-isoleucine, and tert-butylammonium chloride was 1:3.2:0.25:2.2:2.2:1.75:0.5, and the molar ratio of benzophenone to dichloroethane was 1 mol:35 mL. The reaction solution was cooled to room temperature, filtered using a silica gel column (the column was rinsed with dichloroethane), and concentrated under vacuum before being filtered with silica gel (V). 乙酸乙酯 V 正己烷 The stabilizer is obtained by purification using a ratio of 1:2. 1 The H NMR results are as follows: 1 H NMR (C 23 H19 F2NO3, 400 MHz, DMSO-d6) δ 8.63 (s, 1H),7.78 (dd, 4H), 7.62-7.42 (m, 5H), 7.25 (dd, 4H), 5.32 (s, 1H), 4.63 (s, 2H),4.26 (s, 2H);HRMS(ESI) calcd for C 23 H 19 F2NO3[M+H] + 396.13, found 396.14.

[0038] The preparation process of the 6,6'-bis[(3-benzyloxy-1,2-propanediol)oxy]bis(1-hexanol) includes the following steps:

[0039]

[0040] a. Under nitrogen protection, 3-benzyloxy-1,2-propanediol was added to anhydrous N,N-dimethylformamide. Sodium hydride was added at 0°C, the mixture was heated to 80°C and stirred for 40 min. After cooling to room temperature, 2-(6-bromohexoxy)tetrahydropyran was added, stirred until homogeneous, and then heated to 80°C for 17 h. The molar ratio of 3-benzyloxy-1,2-propanediol, sodium hydride, and 2-(6-bromohexoxy)tetrahydropyran was 1:4.5:2.8. The molar ratio of 3-benzyloxy-1,2-propanediol to anhydrous N,N-dimethylformamide was 1 mol:12 mL. The reaction solution was quenched with cold water, extracted with ethyl acetate, the organic layer was washed with saturated brine, dried over anhydrous sodium sulfate, filtered, and concentrated. The residue was purified by rapid column chromatography (eluent, V...). 石油醚 V 乙酸乙酯 =80:20), yielding compound 2; compound 2 1 The H NMR results are as follows: 1 H NMR (C 32 H 54 O7, 400 MHz, DMSO-d6) δ 7.30 (s, 5H), 4.61-4.56 (m, 4H), 3.76-3.62 (m, 8H), 3.38-3.35 (m, 9H), 1.80-1.45 (m, 28H); HRMS(ESI) calcd for C 32 H 54 O7[M+H] + 551.39, found 551.40.

[0041] b. Compound 2 was added to ethanol and stirred until homogeneous. p-Toluenesulfonic acid was then added, and the reaction was allowed to proceed for 20 hours. The molar ratio of compound 2 to p-toluenesulfonic acid was 1:1.5, and the volume ratio of compound 2 to ethanol was 1 mol:45 mL. After the reaction was complete, the reaction solution was quenched with dilute sodium bicarbonate solution, the solvent was extracted with ethyl acetate, the organic layer was washed with brine, dried over anhydrous sodium sulfate, filtered, and concentrated. The residue was purified by rapid chromatography (eluent, V...). 二氯甲烷 V 甲醇 =95:5) to obtain 6,6'-bis[(3-benzyloxy-1,2-propanediol)oxy]bis(1-hexanol) 1 The H NMR results are as follows: 1 H NMR (C 22 H 38 O5, 400 MHz, DMSO-d6) δ 7.30 (s, 5H), 4.71 (s, 2H), 4.65 (s, 2H), 3.65-3.62 (m, 7H), 3.38-3.36(m, 6H), 1.61-1.45 (m, 16H); HRMS(ESI) calcd for C 22 H 38 O5[M+H] + 383.27, found 383.28.

[0042] The present invention also provides a method for preparing a polyurethane adhesive composition, wherein the preparation method comprises:

[0043] S1. Hexamethylene diisocyanate was heated to 70°C, and polytetrahydrofuran ether diol that had been vacuum dehydrated was added and reacted for 60 min to obtain a prepolymer.

[0044] S2. Heat the prepolymer obtained in step S1 to 80°C, add 6,6'-bis[(3-benzyloxy-1,2-propanediol)oxy]bis(1-hexanol), stabilizer, and stannous octoate, stir and react for 3 hours, then add BYK-019 and stir for 35 minutes to obtain the final product.

[0045] Example 2

[0046] A polyurethane adhesive composition, by weight, comprises the following components: 50 parts of polytetrahydrofuran ether diol (number average molecular weight 1000), 8 parts of 6,6'-bis[(3-benzyloxy-1,2-propanediol)oxy]bis(1-hexanol), 3 parts of stabilizer, 35 parts of diisocyanate (toluene-2,4-diisocyanate), 0.1 parts of catalyst (dibutyltin dilaurate), and 0.8 parts of defoamer (BYK-024);

[0047] The preparation process of the stabilizer includes the following steps:

[0048] (1) Difluorobromoacetic acid, 4-aminomethylbenzyl alcohol, triethylamine, and 1H-benzotriazol-1-yloxytripyrrolidinyl hexafluorophosphate were added to anhydrous N,N-dimethylformamide and reacted for 8 h; the molar ratio of difluorobromoacetic acid, 4-aminomethylbenzyl alcohol, triethylamine, and 1H-benzotriazol-1-yloxytripyrrolidinyl hexafluorophosphate was 1:2.5:2:1, and the molar ratio of difluorobromoacetic acid to anhydrous N,N-dimethylformamide was 1 mol:20 mL; then water was added for dilution and extraction with ethyl acetate was performed. The organic layer was washed with saturated brine, dried, and filtered to remove the solvent, and the residue was obtained by column chromatography (V 乙酸乙酯 V 正己烷 The mixture of compounds 1, with a ratio of 30:70, was purified to obtain compound 1; compound 1... 1 The H NMR characterization results are the same as in Example 1;

[0049] (2) Under a nitrogen atmosphere, benzophenone, compound 1, dichlorobis(4-methylisopropylphenyl)ruthenium(II), sodium carbonate, silver trifluoroacetate, N-acetyl-L-isoleucine, and tert-butylammonium chloride were added to dichloroethane and stirred evenly at room temperature. The mixture was then heated to 120°C and reacted for 48 hours. The molar ratio of benzophenone, compound 1, dichlorobis(4-methylisopropylphenyl)ruthenium(II), sodium carbonate, silver trifluoroacetate, N-acetyl-L-isoleucine, and tert-butylammonium chloride was 1:3:0.2:2:2:1.5:0.6, and the molar ratio of benzophenone to dichloroethane was 1 mol:30 mL. The reaction solution was cooled to room temperature, filtered using a silica gel column (the column was rinsed with dichloroethane), and concentrated under vacuum before being filtered with silica gel (V). 乙酸乙酯 V 正己烷 The stabilizer is obtained by purification using a ratio of 1:2. 1 The H NMR characterization results are the same as in Example 1.

[0050] The preparation process of the 6,6'-bis[(3-benzyloxy-1,2-propanediol)oxy]bis(1-hexanol) includes the following steps:

[0051] a. Under nitrogen protection, 3-benzyloxy-1,2-propanediol was added to anhydrous N,N-dimethylformamide. Sodium hydride was added at 0°C, the mixture was heated to 75°C and stirred for 45 min. After cooling to room temperature, 2-(6-bromohexoxy)tetrahydropyran was added, stirred until homogeneous, and then heated to 75°C for 18 h. The molar ratio of 3-benzyloxy-1,2-propanediol, sodium hydride, and 2-(6-bromohexoxy)tetrahydropyran was 1:4:2.4. The molar ratio of 3-benzyloxy-1,2-propanediol to anhydrous N,N-dimethylformamide was 1 mol:8 mL. The reaction solution was quenched with cold water, extracted with ethyl acetate, the organic layer was washed with saturated brine, dried over anhydrous sodium sulfate, filtered, and concentrated. The residue was purified by rapid column chromatography (eluent, V...). 石油醚 V 乙酸乙酯 =80:20), yielding compound 2; compound 2 1 The H NMR characterization results are the same as in Example 1.

[0052] b. Compound 2 was added to ethanol and stirred until homogeneous. p-Toluenesulfonic acid was then added, and the reaction was allowed to proceed for 16 hours. The molar ratio of compound 2 to p-toluenesulfonic acid was 1:1.4, and the volume ratio of compound 2 to ethanol was 1 mol:40 mL. After the reaction was complete, the reaction solution was quenched with dilute sodium bicarbonate solution, the solvent was extracted with ethyl acetate, the organic layer was washed with brine, dried over anhydrous sodium sulfate, filtered, and concentrated. The residue was purified by rapid chromatography (eluent, V...). 二氯甲烷 V 甲醇 =95:5) to obtain 6,6'-bis[(3-benzyloxy-1,2-propanediol)oxy]bis(1-hexanol) 1 The H NMR characterization results are the same as in Example 1.

[0053] The present invention also provides a method for preparing a polyurethane adhesive composition, wherein the preparation method comprises:

[0054] S1. Toluene-2,4-diisocyanate was heated to 75°C, and polytetrahydrofuran ether diol that had been vacuum dehydrated was added and reacted for 45 min to obtain the prepolymer.

[0055] S2. Heat the prepolymer obtained in step S1 to 85°C, add 6,6'-bis[(3-benzyloxy-1,2-propanediol)oxy]bis(1-hexanol), stabilizer, and dibutyltin dilaurate, stir and react for 2 hours, then add BYK-024 and stir for 30 minutes to obtain the final product.

[0056] Example 3

[0057] A polyurethane adhesive composition, by weight, comprises the following components: 55 parts of polytetrahydrofuran ether diol (number average molecular weight 2000), 15 parts of 6,6'-bis[(3-benzyloxy-1,2-propanediol)oxy]bis(1-hexanol), 5 parts of stabilizer, 45 parts of diisocyanate (hexamethylene diisocyanate), 0.5 parts of catalyst (stannous octoate), and 0.8 parts of defoamer (BYK-024);

[0058] The preparation process of the stabilizer includes the following steps:

[0059] (1) Difluorobromoacetic acid, 4-aminomethylbenzyl alcohol, triethylamine, and 1H-benzotriazol-1-yloxytripyrrolidinyl hexafluorophosphate were added to anhydrous N,N-dimethylformamide and reacted for 8 h; the molar ratio of difluorobromoacetic acid, 4-aminomethylbenzyl alcohol, triethylamine, and 1H-benzotriazol-1-yloxytripyrrolidinyl hexafluorophosphate was 1:3:2.6:1.3, and the molar ratio of difluorobromoacetic acid to anhydrous N,N-dimethylformamide was 1 mol:30 mL; then water was added for dilution and extraction with ethyl acetate was performed. The organic layer was washed with saturated brine, dried, and filtered to remove the solvent, and the residue was obtained by column chromatography (V 乙酸乙酯 V 正己烷 The mixture of compounds 1, with a ratio of 30:70, was purified to obtain compound 1; compound 1... 1 The H NMR characterization results are the same as in Example 1;

[0060] (2) Under a nitrogen atmosphere, benzophenone, compound 1, dichlorobis(4-methylisopropylphenyl)ruthenium(II), sodium carbonate, silver trifluoroacetate, N-acetyl-L-isoleucine, and tert-butylammonium chloride were added to dichloroethane and stirred evenly at room temperature. The mixture was then heated to 140°C and reacted for 36 h. The molar ratio of benzophenone, compound 1, dichlorobis(4-methylisopropylphenyl)ruthenium(II), sodium carbonate, silver trifluoroacetate, N-acetyl-L-isoleucine, and tert-butylammonium chloride was 1:3.3:0.3:2.5:2:2:0.8, and the molar ratio of benzophenone to dichloroethane was 1 mol:40 mL. The reaction solution was cooled to room temperature, filtered using a silica gel column (the column was rinsed with dichloroethane), and concentrated under vacuum before being filtered with silica gel (V). 乙酸乙酯 V 正己烷 The stabilizer is obtained by purification using a ratio of 1:2. 1 The H NMR characterization results are the same as in Example 1.

[0061] The preparation process of the 6,6'-bis[(3-benzyloxy-1,2-propanediol)oxy]bis(1-hexanol) includes the following steps:

[0062] a. Under nitrogen protection, 3-benzyloxy-1,2-propanediol was added to anhydrous N,N-dimethylformamide. Sodium hydride was added at 0°C, the mixture was heated to 85°C and stirred for 30 min, cooled to room temperature, and then 2-(6-bromohexoxy)tetrahydropyran was added. After stirring until homogeneous, the mixture was heated to 85°C and reacted for 16 h. The molar ratio of 3-benzyloxy-1,2-propanediol, sodium hydride, and 2-(6-bromohexoxy)tetrahydropyran was 1:5:3. The molar ratio of 3-benzyloxy-1,2-propanediol to anhydrous N,N-dimethylformamide was 1 mol:15 mL. The reaction solution was quenched with cold water, extracted with ethyl acetate, the organic layer was washed with saturated brine, dried over anhydrous sodium sulfate, filtered, and concentrated. The residue was purified by rapid column chromatography (eluent, V...). 石油醚 V 乙酸乙酯 =80:20), yielding compound 2; compound 2 1 The H NMR characterization results are the same as in Example 1;

[0063] b. Compound 2 was added to ethanol and stirred until homogeneous. p-Toluenesulfonic acid was then added, and the reaction was allowed to proceed for 24 hours. The molar ratio of compound 2 to p-toluenesulfonic acid was 1:1.6, and the volume ratio of compound 2 to ethanol was 1 mol:50 mL. After the reaction was complete, the reaction solution was quenched with dilute sodium bicarbonate solution, the solvent was extracted with ethyl acetate, the organic layer was washed with brine, dried over anhydrous sodium sulfate, filtered, and concentrated. The residue was purified by rapid chromatography (eluent, V...). 二氯甲烷 V 甲醇 =95:5) to obtain 6,6'-bis[(3-benzyloxy-1,2-propanediol)oxy]bis(1-hexanol) 1 The H NMR characterization results are the same as in Example 1.

[0064] The present invention also provides a method for preparing a polyurethane adhesive composition, wherein the preparation method comprises:

[0065] S1. Hexamethylene diisocyanate was heated to 75°C, and polytetrahydrofuran ether diol that had been vacuum dehydrated was added and reacted for 75 min to obtain the prepolymer.

[0066] S2. Heat the prepolymer obtained in step S1 to 85°C, add 6,6'-bis[(3-benzyloxy-1,2-propanediol)oxy]bis(1-hexanol), stabilizer, and stannous octoate, stir and react for 4 hours, then add BYK-024 and stir for 40 minutes to obtain the final product.

[0067] Comparative Example 1

[0068] Comparative Example 1 is essentially the same as Example 1, except that 6,6'-bis[(3-benzyloxy-1,2-propanediol)oxy]bis(1-hexanol) is replaced with 1,4-butanediol.

[0069] Comparative Example 2

[0070] Comparative Example 2 is basically the same as Example 1, except that the stabilizer is omitted.

[0071] Test case

[0072] To investigate the comprehensive performance of the polyurethane adhesives obtained in Examples 1-3 and Comparative Examples 1-2 of this invention, the adhesives of Examples 1-3 and Comparative Examples 1-2 were applied to a clean glass plate surface, cured to form an adhesive film, and then subjected to the following tests:

[0073] (1) Mechanical properties: The tensile strength and elongation at break of the film were tested according to the test standard of GB / T528-2009.

[0074] (2) Chemical corrosion resistance: The film was immersed in a 4 mol / L sodium hydroxide solution for 48 h, and then the tensile strength and elongation at break were tested according to the test standard of GB / T528-2009.

[0075] (3) Water resistance: The water resistance of the film was characterized using a contact angle measuring instrument. The test results are recorded in Table 1.

[0076] (4) Yellowing resistance: Tested according to the test standard of GB / T39822-2021.

[0077] (5) Heat resistance: Place the film in an oven at 150℃ for 5 days and observe whether the film curls, cracks or other phenomena occur. The results of the above tests are recorded in Table 1.

[0078] Table 1

[0079]

[0080] As can be seen from the test results in Table 1, the overall performance of the products obtained in Examples 1-3 of this invention is superior to that of Comparative Examples 1 and 2. In terms of mechanical strength, the products obtained in Examples 1-3 of this invention exhibit good tensile strength and elongation at break, and after immersion in sodium hydroxide, the retention rates of tensile strength and elongation at break are both above 83%, indicating good alkali resistance. In contrast, Comparative Example 1, by replacing 6,6'-bis[(3-benzyloxy-1,2-propanediol)oxy]bis(1-hexanol) with 1,4-butanediol, and Comparative Example 2, by omitting the stabilizer, showed varying degrees of reduction in the retention rates of tensile strength and elongation at break, indicating poorer alkali resistance. This is because in Comparative Example 1, 6,6'-bis[(3-benzyloxy-1,2-propanediol)oxy]bis(1-hexanol) was replaced with 1,4-butanediol. Both 1,4-butanediol and the benzyl alcohol groups in the stabilizer provide crosslinking sites, allowing them to crosslink with the isocyanate groups in the components, further enhancing the mechanical properties of the polyurethane adhesive. In contrast, Comparative Example 2, by omitting the stabilizer, experienced a lower crosslinking density and thus lower mechanical properties.

[0081] The higher the yellowing index, the worse the resistance to yellowing. Comparative Example 2 has the worst hydrophobicity and resistance to yellowing. This is because it omits the stabilizer containing fluorine atoms, which causes a change in the surface energy of the material and prevents the formation of a hydrophobic barrier. At the same time, the yellowing index of the material increases, and the resistance to yellowing decreases.

[0082] Compared with Example 1, the heat resistance of Comparative Examples 1 and 2 decreased, indicating that 6,6'-bis[(3-benzyloxy-1,2-propanediol)oxy]bis(1-hexanol) in this invention can work together with the stabilizer to improve the heat resistance of polyurethane.

[0083] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A polyurethane adhesive composition, characterized in that, The product comprises, by weight parts, the following components: 50-55 parts polytetrahydrofuran ether diol, 8-15 parts 6,6'-bis[(3-benzyloxy-1,2-propanediol)oxy]bis(1-hexanol), 3-5 parts stabilizer, 35-45 parts diisocyanate, 0.1-0.5 parts catalyst, and 0.8-1.5 parts defoamer; the chemical structural formula of the stabilizer is as follows: ； The chemical structural formula of the 6,6'-bis[(3-benzyloxy-1,2-propanediol)oxy]bis(1-hexanol) is as follows: 。 2. The polyurethane adhesive composition according to claim 1, characterized in that, The preparation process of the stabilizer includes the following steps: (1) Difluorobromoacetic acid, 4-aminomethylbenzyl alcohol, triethylamine, and 1H-benzotriazol-1-yloxytripyrrolidinyl hexafluorophosphate were added to a solvent to react, and then compound 1 was obtained by extraction and purification; (2) Benzophenone, compound 1, dichlorobis(4-methylisopropylphenyl)ruthenium(II), sodium carbonate, silver trifluoroacetate, N-acetyl-L-isoleucine and tert-butylammonium chloride were added to a solvent under a nitrogen atmosphere and reacted, and then purified to obtain the product.

3. The polyurethane adhesive composition according to claim 2, characterized in that, In step (1), the molar ratio of difluorobromoacetic acid, 4-aminomethylbenzyl alcohol, triethylamine, and 1H-benzotriazol-1-yloxytripyrrolidinyl hexafluorophosphate is 1:(2.5-3):(2-2.6):(1-1.3), and the ratio of difluorobromoacetic acid to solvent is 1 mol:20-30 mL.

4. The polyurethane adhesive composition according to claim 2, characterized in that, In step (2), the molar ratio of benzophenone, compound 1, dichlorobis(4-methylisopropylphenyl)ruthenium(II), sodium carbonate, silver trifluoroacetate, N-acetyl-L-isoleucine, and tert-butylammonium chloride is 1:(3-3.3):(0.2-0.3):(2-2.5):(2-2.5):(1.5-2):(0.5-0.8), and the volume ratio of benzophenone to solvent is 1 mol:30-40 mL.

5. The polyurethane adhesive composition according to claim 2, characterized in that, The reaction time in step (1) is 8-12 h, and the solvent in step (1) is anhydrous N,N-dimethylformamide; the reaction temperature in step (2) is 120-140℃, and the reaction time is 36-48 h; the solvent in step (2) is dichloroethane.

6. The polyurethane adhesive composition according to claim 1, characterized in that, The preparation process of the 6,6'-bis[(3-benzyloxy-1,2-propanediol)oxy]bis(1-hexanol) includes the following steps: a. Add 3-benzyloxy-1,2-propanediol to the solvent, add sodium hydride and stir, cool to room temperature, then add 2-(6-bromohexyloxy)tetrahydropyran to continue the reaction; after the reaction is complete, extract, wash, concentrate and purify the reaction solution to obtain compound 2. b. Add compound 2 and p-toluenesulfonic acid to a solvent to react; extract, wash, concentrate and purify the reaction solution to obtain the final product.

7. The polyurethane adhesive composition according to claim 6, characterized in that, In step a, the molar ratio of 3-benzyloxy-1,2-propanediol, sodium hydride, and 2-(6-bromohexyloxy)tetrahydropyran is 1:(4-5):(2.4-3); the volume ratio of 3-benzyloxy-1,2-propanediol to solvent is 1 mol: 8-15 mL; the stirring temperature is 75-85℃ and the time is 30-45 min; the reaction temperature is 75-85℃ and the time is 16-18 h; the solvent is anhydrous N,N-dimethylformamide.

8. The polyurethane adhesive composition according to claim 6, characterized in that, In step b, the molar ratio of compound 2 to p-toluenesulfonic acid is 1:(1.4-1.6), and the reaction time is 16-24 h; the volume ratio of compound 2 to solvent is 1 mol: 40-50 mL; and the solvent is ethanol.

9. The polyurethane adhesive composition according to claim 1, characterized in that, The polytetrahydrofuran ether diol has a number average molecular weight of 1000-2000; the diisocyanate is hexamethylene diisocyanate or toluene-2,4-diisocyanate; the catalyst is stannous octoate or dibutyltin dilaurate; and the defoamer is BYK-019 or BYK-024.

10. A method for preparing a polyurethane adhesive composition according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Heat the diisocyanate to 70-75℃, add the dehydrated polytetrahydrofuran ether diol and react for 45-75 min to obtain the prepolymer; S2. Heat the prepolymer obtained in step S1 to 80-85℃, add 6,6'-bis[(3-benzyloxy-1,2-propanediol)oxy]bis(1-hexanol), stabilizer, and catalyst, stir and react for 2-4 hours, then add defoamer and stir for 30-40 minutes to obtain the final product.

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