Rosin-based dihydric alcohol chain extender, underwater high-strength polyurethane adhesive prepared by using the chain extender and preparation method thereof

Abstract

The application belongs to the technical field of polymer material preparation, and specifically discloses a rosin-based dihydric alcohol chain extender, underwater high-strength polyurethane adhesive prepared by using the chain extender and a preparation method of the adhesive. The rosin-based dihydric alcohol chain extender is synthesized by using dehydroabietic acid as a raw material and sequentially through acyl chloride, dehalogenation and substitution reactions; the chain extender is subjected to polyurethanization reaction under certain conditions to prepare the polyurethane adhesive with adjustable structure and good underwater adhesion. At present, there is no report on a synthesis method for preparing high-strength adhesive by using rosin as a raw material in China, the application fully utilizes the unique advantages of the structure of rosin, opens up a new way for high-value utilization of rosin, and provides a preparation method of a series of rosin-based underwater adhesives. The application has simple preparation process, relatively low cost, is green and sustainable.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of polymer material preparation, and particularly relates to a rosin-based diol chain extender, underwater high-strength polyurethane adhesive prepared by using the chain extender and a preparation method of the adhesive. BACKGROUND

[0002] Adhesives are ubiquitous in daily life, but most lose adhesion in the presence of water. Water interferes with adhesives through two key mechanisms. First, water at the interface reduces the available surface area between the substrate and adhesive; second, water diffuses into the adhesive, reducing the cohesive strength by interfering with physical crosslinks or acting as a chemically inert plasticizer. To address these issues, researchers have proposed various methods for synthesizing novel underwater adhesives.

[0003] Researchers have adopted biomimetic designs based on the supramolecular or electrostatic interactions of underwater adhesion mechanisms of mussels, sandcastle worms, but the biomimetic mechanism focuses on achieving strong adhesion in the state of water swelling of the adhesive. Another method is to design a strongly hydrophobic self-adhesive material that can remove the interface water and maintain the volume cohesive strength by preventing water swelling. For example, researchers combine hydrophobic poly(N-vinylcaprolactam) with short molecular weight poly(ethylene glycol) to produce an adhesive with low water content and high adhesive strength, but the adhesion fails when the water content exceeds 30 wt%; or adding hydrophobic aliphatic side chains to polyesters with catechol functional groups is proved to improve underwater adhesion performance, but requires ultraviolet-induced chemical crosslinking. SUMMARY

[0004] In view of the above problems existing in the prior art, the present application aims to provide a rosin-based diol chain extender, underwater high-strength polyurethane adhesive prepared by using the chain extender and a preparation method of the adhesive.

[0005] In order to solve the above problems, the technical scheme adopted by the present application is as follows:

[0006] A rosin-based diol chain extender is prepared by the following method:

[0007] (1) Dehydroabietic acid is subjected to acyl chloride reaction, then bromoethanol and an acid binding agent are added for dehalogenation reaction, and the product is purified to obtain 2-bromoethyl dehydroabietate;

[0008] (2) 2-bromoethyl dehydroabietate and diethanolamine are reacted at 70-90°C for 18-30 h, and the rosin-based diol chain extender is obtained after purification and purification;

[0009] Optionally, the acyl chloride reaction in step (1) is specifically as follows: the dehydroabietic acid is dissolved in ethyl acetate, oxalyl chloride is added, and the reaction is carried out at 20-60℃ for 3-6 h, wherein the molar ratio of the carboxyl in the dehydroabietic acid to the acyl chloride in the oxalyl chloride is 1:(1-2.2).

[0010] Optionally, the dehalogenation reaction condition in step (1) is as follows: the reaction is carried out at 0-20℃ for 2-5 h; wherein the acid binding agent is triethylamine, and the molar ratio of the carboxyl in the dehydroabietic acid to the hydroxyl in the bromoethanol is 1:(1-2.2).

[0011] Optionally, the molar amount of diethanolamine in step (2) is 1-2 times the molar amount of bromoethanol.

[0012] The method for preparing the underwater high-strength polyurethane adhesive by using the rosin-based dihydric alcohol chain extender is as follows: first, the hydroxyl-terminated chain extender, a catalyst and isocyanate are reacted to obtain an isocyanate-terminated prepolymer, then the rosin-based dihydric alcohol chain extender and 1,4-butanediol are added to crosslink and terminate the prepolymer, and the liquid material is cured to obtain the rosin-based polyurethane adhesive.

[0013] Optionally, 3-4 parts of the hydroxyl-terminated chain extender and 11 parts of diisocyanate are mixed and stirred in N,N-dimethylacetamide, a catalyst is added, and the reaction is carried out at 60-80℃ for 2-5 h to obtain the isocyanate-terminated prepolymer; 4-5 parts of the rosin-based dihydric alcohol chain extender and 1-1.8 parts of 1,4-butanediol are added thereto, and the reaction is continued at 60-80℃ for 4-6 h.

[0014] Optionally, the curing is as follows: the liquid material is poured into a mold, placed in an oven at 75-90℃ for 20-24 h, and then vacuum treated at 80-120℃ for 10-15 h.

[0015] Optionally, the hydroxyl-terminated chain extender is polytetrahydrofuran, polyethylene glycol, polyetheramine, polycarbonate diol or polypropylene glycol, and the molecular weight is 800-2000; the catalyst is a tin catalyst; and the isocyanate is hexamethylene diisocyanate, isophorone diisocyanate, methylcyclohexyl diisocyanate, dicyclohexylmethylene diisocyanate, 2,2,4-trimethylhexane diisocyanate, phenylene diisocyanate, m-1,4-methylphenylene diisocyanate, p-1,4-methylphenylene diisocyanate or dimer acid diisocyanate.

[0016] The underwater high-strength polyurethane adhesive prepared according to the above method.

[0017] Compared with the prior art, the present application has the following beneficial effects:

[0018] The present application firstly prepares a rosin-based diol chain extender from rosin as a raw material and designs a structure-adjustable underwater adhesive with high adhesive strength. The rosin raw material is abundant in source and low in production cost, and meets the concept of green environmental protection and sustainable development. The rosin-based polyurethane has hydrogen bond interaction from urethane, and the high spatial volume of hydrogenated phenanthrene ring can improve the topological entanglement of the molecular chain, showing high cohesive strength, and also easily flows on the surface of the substrate, significantly improving the adhesive strength of the hydrogel by increasing the volume cohesive strength and preventing interface delamination or fracture; in addition, the strong non-polar hydrogenated phenanthrene ring has hydrophobicity and can improve the nanophase separation between the main chain and the dynamic hydrogen bond, thereby limiting the diffusion of a large amount of water. The rosin-based polyurethane of the present application fully utilizes the unique advantages of the structure of rosin, and opens up a new way for the high-value utilization of rosin. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The synthesis route map of the rosin-based diol chain extender in Example 1 of the present application is shown in the figure.

[0020] Figure 2 The infrared spectrum of the rosin-based diol chain extender obtained in Example 1 is shown in the figure.

[0021] Figure 3 The structure of the oleic acid-based diol chain extender obtained in Comparative Example 1 is shown in the figure.

[0022] Figure 4 The structure of the lauryl diol chain extender obtained in Comparative Example 2 is shown in the figure.

[0023] Figure 5 The structure of the cinnamyl diol chain extender obtained in Comparative Example 3 is shown in the figure. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments.

[0025] Example 1

[0026] (1) Dehydroabietic acid (100 g, 0.33 mol) was dissolved in ethyl acetate, and oxalyl chloride (46.07 g, 0.363 mol) was added under ice bath, and the reaction was carried out under reflux at 50℃ for 5 h to obtain dehydroabietic acid chloride, then triethylamine (36.73 g, 0.363 mol) and bromoethanol (82.48 g, 0.66 mol) were added dropwise under ice bath, and the reaction was carried out at 20℃ for 5 h, then the precipitate was filtered off, the solvent layer was collected, and the unreacted bromoethanol was removed by water washing until the lower inorganic phase reached neutral pH, then anhydrous magnesium sulfate was used to remove water, and the product 2-bromoethyl dehydroabietate was obtained by suction filtration.

[0027] (2) To 2-bromoethyl dehydroabietyl ester, add diethanolamine (110 g, 1.05 mol), heat under oil bath at 80 °C for 24 h. Wash with water to remove unreacted amine, wash with deionized water until the pH of the lower inorganic phase is neutral, collect the organic phase, remove water with anhydrous magnesium sulfate, and filter under suction. After rotary evaporation, the dehydroabietyl glycol chain extender is obtained. The synthetic route map is shown in Figure 1 .

[0028] (3) 3.5 parts of 1000 molecular weight polytetrahydrofuran, 11 parts of isophorone diisocyanate, and an appropriate amount of catalyst dibutyltin dilaurate are mixed and stirred in N,N-dimethylacetamide, and reacted at 80 °C for 3 h to obtain a prepolymer capped with isocyanate. 5 parts of dehydroabietyl glycol and 1.5 parts of 1,4-butanediol are added and reacted at 60 °C for 6 h. After the reaction is completed, the liquid material is poured into a polypropylene (PP) mold, placed in an oven at 80 °C for 24 h, and then vacuum treated at 120 °C for 12 h to obtain a dehydroabietyl urethane adhesive.

[0029] Example 2

[0030] (1) Dissolve dehydroabietic acid (100 g, 0.33 mol) in ethyl acetate, and add oxalyl chloride (31.73 g, 0.25 mol) under ice bath. React under reflux at 60 °C for 3 h to obtain dehydroabietic acid chloride. Then add acid binding agent triethylamine (36.73 g, 0.363 mol) and bromoethanol (47.49 g, 0.38 mol) dropwise under ice bath, and react at 20 °C for 5 h. Filter out the precipitate, collect the solvent layer, wash with water to remove unreacted bromoethanol, and wash until the pH of the lower inorganic phase is neutral. Remove water with anhydrous magnesium sulfate, and filter under suction to obtain the product 2-bromoethyl dehydroabietyl ester.

[0031] (2) To 2-bromoethyl dehydroabietyl ester, add diethanolamine (79.90 g, 0.76 mol), and heat under oil bath at 70 °C for 30 h. Wash with water to remove unreacted amine, wash with deionized water until the pH of the lower inorganic phase is neutral, collect the organic phase, remove water with anhydrous magnesium sulfate, and filter under suction. After rotary evaporation, the dehydroabietyl glycol chain extender is obtained. The synthetic route map is shown in Figure 1 .

[0032] (3) 3 parts of 1000 molecular weight polytetrahydrofuran, 11 parts of isophorone diisocyanate, and an appropriate amount of catalyst dibutyltin dilaurate are mixed and stirred in N,N-dimethylacetamide, and reacted at 70 °C for 5 h to obtain a prepolymer capped with isocyanate. 4 parts of dehydroabietyl glycol and 1.8 parts of 1,4-butanediol are added and reacted at 70 °C for 5 h. After the reaction is completed, the liquid material is poured into a polypropylene (PP) mold, placed in an oven at 80 °C for 22 h, and then vacuum treated at 100 °C for 15 h to obtain a dehydroabietyl urethane adhesive.

[0033] Example 3

[0034] (1) Dehydroabietic acid (100 g, 0.33 mol) was dissolved in ethyl acetate, and oxalyl chloride (23.0 g, 0.181 mol) was added under ice bath, and dehydroabietic acid chloride was obtained by refluxing at 50 °C for 5 h, then triethylamine (36.73 g, 0.363 mol) and bromoethanol (73.73 g, 0.59 mol) were added dropwise under ice bath, and the reaction was carried out at 10 °C for 3 h, the precipitate was filtered off, and the solvent layer was collected, and the unreacted bromoethanol was removed by water washing until the pH of the lower inorganic phase was about neutral, and then anhydrous magnesium sulfate was used to remove water, and the product 2-bromoethyl dehydroabietate was obtained by suction filtration.

[0035] (2) Diethanolamine (74.65 g, 0.71 mol) was added to 2-bromoethyl dehydroabietate, and the reaction was carried out at 90 °C for 20 h under oil bath heating, and then the unreacted amine was removed by water washing, and the organic phase was collected, and then anhydrous magnesium sulfate was used to remove water, and then the rosin-based diol chain extender was obtained by suction filtration and rotary evaporation. Figure 1 .

[0036] (3) 4 parts of polytetrahydrofuran with a molecular weight of 1000, 11 parts of hexamethylene diisocyanate, and a proper amount of catalyst dibutyltin dilaurate were mixed and stirred in N,N-dimethylacetamide, and the reaction was carried out at 60 °C for 4 h to obtain a prepolymer capped with isocyanate; 4.5 parts of rosin-based diol and 1 part of 1,4-butanediol were added and the reaction was continued at 80 °C for 4 h; after the reaction was completed, the liquid material was poured into a polypropylene (PP) mold, and placed in an oven at 90 °C for 20 h, and then vacuum treatment was carried out at 120 °C for 10 h to obtain a rosin-based polyurethane adhesive.

[0037] Comparative Example 1

[0038] (1) Oleoyl chloride (100 g, 0.33 mol) was dissolved in ethyl acetate, and triethylamine (33.39 g, 0.33 mol) and bromoethanol (82.48 g, 0.66 mol) were added under ice bath, and the reaction was carried out at 20 °C for 5 h, and then the precipitate was filtered off, and the solvent layer was collected, and then the unreacted bromoethanol was removed by water washing until the pH of the lower inorganic phase was about neutral, and then anhydrous magnesium sulfate was used to remove water, and the product 2-bromoethyl oleate was obtained by suction filtration.

[0039] (2) Diethanolamine (145.09 g, 1.38 mol) was added to 2-bromoethyl oleate, and the reaction was carried out at 80 °C for 24 h under oil bath heating, and then the unreacted amine was removed by water washing, and then the organic phase was collected, and then anhydrous magnesium sulfate was used to remove water, and then the oleic acid-based diol chain extender was obtained by suction filtration and rotary evaporation.

[0040] (3) 3.5 parts of polytetrahydrofuran with a molecular weight of 1000, 11 parts of isophorone diisocyanate and an appropriate amount of catalyst dibutyltin dilaurate were mixed and stirred in N,N-dimethylacetamide, and reacted at 80°C for 3 h to obtain a prepolymer capped with isocyanate; 5 parts of oleic acid-based diol and 1.5 parts of 1,4-butanediol were added and reacted at 60°C for 6 h; after the reaction was completed, the liquid material was poured into a polypropylene (PP) mold, placed in an oven at 80°C for 24 h, and then vacuum treated at 120°C for 12 h to obtain an oleic acid-based polyurethane adhesive.

[0041] Comparative Example 2

[0042] (1) Lauric acid chloride (100 g, 0.46 mol) was dissolved in ethyl acetate, and triethylamine (46.55 g, 0.46 mol) and bromoethanol (114.97 g, 0.92 mol) were added under ice bath, and reacted at 20°C for 5 h. The precipitate was filtered off, and the solvent layer was collected. The unreacted bromoethanol was removed by water washing until the pH of the lower inorganic phase was about neutral. Anhydrous magnesium sulfate was used to remove water, and the product 2-bromoethyl laurate was obtained by suction filtration.

[0043] (2) Diethanolamine (145.09 g, 1.38 mol) was added to 2-bromoethyl laurate, and heated at 80°C in an oil bath for 24 h. The unreacted amine was removed by water washing until the pH was neutral. The organic phase was collected, and anhydrous magnesium sulfate was used to remove water. After suction filtration and rotary evaporation, the lauryl diol chain extender was obtained.

[0044] (3) 3.5 parts of polytetrahydrofuran with a molecular weight of 1000, 11 parts of isophorone diisocyanate and an appropriate amount of catalyst dibutyltin dilaurate were mixed and stirred in N,N-dimethylacetamide, and reacted at 80°C for 3 h to obtain a prepolymer capped with isocyanate; 5 parts of oleic acid-based diol and 1.5 parts of 1,4-butanediol were added and reacted at 60°C for 6 h; after the reaction was completed, the liquid material was poured into a polypropylene (PP) mold, placed in an oven at 80°C for 24 h, and then vacuum treated at 120°C for 12 h to obtain an oleic acid-based polyurethane adhesive.

[0045] Comparative Example 3

[0046] (1) Cinnamoyl chloride (100 g, 0.60 mol) was dissolved in ethyl acetate, and triethylamine (60.71 g, 0.6 mol) and bromoethanol (124.97 g, 1.2 mol) were added under ice bath, and reacted at 20°C for 5 h. The precipitate was filtered off, and the solvent layer was collected. The unreacted bromoethanol was removed by water washing until the pH of the lower inorganic phase was about neutral. Anhydrous magnesium sulfate was used to remove water, and the product 2-bromoethyl cinnamate was obtained by suction filtration.

[0047] (2) To 2-bromoethyl cinnamate, add diethanolamine (126.17 g, 1.20 mol), heat in oil bath at 80℃ for 24 h. Wash with water to remove unreacted amine, wash with deionized water until pH is neutral, collect the organic phase, remove water with anhydrous magnesium sulfate, filter, and rotary evaporate to obtain the cinnamyl diol chain extender.

[0048] (3) 3.5 parts of 1000 molecular weight polytetrahydrofuran, 11 parts of isofuranone diisocyanate and an appropriate amount of catalyst dibutyltin dilaurate are mixed and stirred in N,N-dimethylacetamide, and reacted at 80℃ for 3 h to obtain a pre-polymer capped with isocyanate; 5 parts of cinnamyl diol and 1.5 parts of 1,4-butanediol are added and reacted at 60℃ for 6 h; after the reaction is completed, the liquid material is poured into a polypropylene (PP) mold, placed in an oven at 80℃ for 24 h, and then vacuum treated at 120℃ for 12 h to obtain a cinnamyl polyurethane adhesive.

[0049] Test standard: GB-T2790-1995 "Adhesives 180° peel strength test method Flexible materials on rigid materials".

[0050] Example 1 is a high-strength rosin-based polyurethane adhesive prepared by the present application. Comparative Example 1 is a rosin ring structure replaced by oleic acid, Comparative Example 2 is a rosin ring structure replaced by lauric acid, and Comparative Example 3 is a rosin ring structure replaced by cinnamic acid. By comparing the underwater mechanical properties of Example 1 with Comparative Examples 1, 2 and 3, it is shown that loose hard domains are beneficial to maintaining dynamic characteristics, thereby achieving higher adhesive strength. The rosin-based polyurethane adhesive prepared by the method of the present application has higher underwater adhesive strength.

[0051] Table 1 Comparison of underwater mechanical properties of various examples and comparative examples

[0052]

[0053] The above description is merely illustrative of the application and is not intended to limit the scope of the application. Any modification without departing from the concept and principle of the application, which is not creative work, shall belong to the scope of protection of the present application.

Claims

1. A rosin-based diol chain extender characterized by, The structural formula is: 。 2. A process for the preparation of a rosin-based diol chain extender as claimed in claim 1, characterized in that, Preparation is carried out by the following method: (1) carrying out acyl chloride reaction on dehydroabietyl acid, then adding bromoethanol and deacid reagent to carry out dehalogenation reaction, and the product is purified to obtain 2-bromoethyl dehydroabietyl ester; (2) reacting 2-bromoethyl dehydroabietyl ester with diethanolamine at 70-90 DEG C for 18-30 h, and purifying and purifying to obtain the rosin-based dihydric alcohol chain extender; The reaction formula is: 。 3. A process for the preparation of a rosin-based diol chain extender according to claim 2, characterized in that, The acyl chloride reaction in step (1) is specifically as follows: dehydroabietyl acid is dissolved in ethyl acetate, oxalyl chloride is added, and reaction is carried out at 20-60 DEG C for 3-6 h, wherein the molar ratio of carboxyl in dehydroabietyl acid to acyl chloride in oxalyl chloride is 1:(1-2.2).

4. The method of claim 2, wherein the rosin-based diol chain extender is prepared by the steps of: a) reacting a rosin acid with a diol in the presence of a catalyst to form a rosin-based diol chain extender; and b) recovering the rosin-based diol chain extender. The dehalogenation reaction condition in step (1) is: reaction at 0-20 °C for 2 5 h; wherein the acid binding agent is triethylamine, and the molar ratio of the carboxyl in dehydroabietic acid to the hydroxyl in bromoethanol is 1: (1-2.2).

5. The method of claim 2, wherein the rosin-based diol chain extender is prepared by the steps of: a) reacting a rosin acid with a diol in the presence of a catalyst to form a rosin-based diol chain extender; and b) recovering the rosin-based diol chain extender. The molar amount of diethanolamine in step (2) is 1-2 times the amount of bromoethanol.

6. A process for preparing an underwater polyurethane adhesive using the rosin based diol chain extender of claim 1, characterized by, First, the chain extender terminated by hydroxyl, catalyst and isocyanate are reacted to obtain the prepolymer terminated by isocyanate, then the rosin-based dihydric alcohol chain extender and 1,4-butanediol are added to crosslink and terminate, and the liquid material is cured to obtain the rosin-based polyurethane adhesive.

7. The method of making an underwater polyurethane adhesive according to claim 6, characterized in that, According to the molar amount, 3-4 parts of the chain extender terminated by hydroxyl and 11 parts of diisocyanate are mixed and stirred in N,N-dimethylacetamide, a catalyst is added, and reaction is carried out at 60-80 DEG C for 2-5 h to obtain the prepolymer terminated by isocyanate; 4-5 parts of the rosin-based dihydric alcohol chain extender and 1-1.8 parts of 1,4-butanediol are added, and reaction is continued at 60-80 DEG C for 4-6 h.

8. The method of making an underwater polyurethane adhesive according to claim 6, characterized in that, The curing is that the liquid material is poured into a mold, placed in an oven at 75-90 DEG C for 20-24 h, and then vacuum treated at 80-120 DEG C for 10-15 h.

9. The method of claim 6, wherein the method further comprises, The chain extender terminated by hydroxyl is polytetrahydrofuran, polyethylene glycol, polyether amine, polycarbonate diol or polypropylene glycol, and the molecular weight is 800-2000; the catalyst is a tin catalyst; and the isocyanate is hexamethylene diisocyanate, isophorone diisocyanate, methylcyclohexyl diisocyanate, dicyclohexylmethylene diisocyanate, 2,2,4-trimethylhexane diisocyanate, phenylene diisocyanate, m-1,4-methylphenylmethylene diisocyanate, p-1,4-methylphenylmethylene diisocyanate or diisocyanate of dimer acid.

10. The underwater polyurethane adhesive prepared by the method according to any one of claims 6-9.

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