Preparation method of weather-resistant environment-friendly adhesive

Abstract

The invention relates to the technical field of adhesives, and discloses a preparation method of a weather-resistant environment-friendly adhesive, which comprises the following steps: reacting polyethylene glycol diglycidyl ether, perfluoroalkyl alcohol and diisocyanate to obtain an isocyanate-terminated fluorine-containing polyurethane prepolymer, and mixing the isocyanate-terminated fluorine-containing polyurethane prepolymer with hydroxy acrylic resin to obtain the weather-resistant environment-friendly adhesive. The polyurethane prepolymer has a cross-linking curing reaction with hydroxyl groups of the acrylic resin, cohesion of the acrylic resin is enhanced, tensile shear strength and bonding performance of the adhesive are improved, and the polyurethane prepolymer contains a water-resistant and heat-resistant perfluoroalkyl chain which is introduced into a curing network of the acrylic resin, so that the water-resistant and heat-resistant perfluoroalkyl chain has excellent water-resistant and heat-resistant performance, and the water-resistant and heat-resistant performance of the adhesive is improved. The damp-heat aging resistance and the weather resistance of the adhesive are favorably improved.

Description

Technical Field

[0001] The invention relates to the technical field of adhesives, and in particular to a method for preparing a weather-resistant and environmentally friendly adhesive. Background Art

[0002] Acrylic resin adhesives are widely used in label paper, safety signs, automobile manufacturing, furniture and electrical appliances due to their good curing performance, impact resistance and mechanical strength. Improving the moisture and heat resistance and weather resistance of acrylic resin adhesives will help expand their practical applications in outdoor signs, exterior wall insulation and other fields.

[0003] Polyurethane is a high-performance polymer with high mechanical strength, good toughness and excellent heat resistance. It has important applications in adhesives, elastomer materials, etc. Chinese patent CN116875236B discloses a method for preparing a polyurethane-modified acrylic resin pressure-sensitive adhesive for microprisms. The polyurethane-modified acrylic resin pressure-sensitive adhesive prepared by using acrylic soft monomers, functional monomers, epoxy-modified polyurethane prepolymer solutions, etc. as raw materials has good adhesion, elasticity, low temperature resistance, creep resistance and other characteristics. However, the pressure-sensitive adhesive of this patent does not have good resistance to moisture, heat and weathering. Summary of the invention

[0004] The technical problem solved by the invention is to solve the problem of poor weather resistance and bonding performance of acrylic resin adhesive.

[0005] The technical solution of the present invention is: a method for preparing a weather-resistant environmentally friendly adhesive:

[0006] Step (1), adding polyethylene glycol diglycidyl ether and perfluoroalkyl alcohol (structural formula ), heated to 80-95° C., added boron trifluoride etherate dropwise, stirred for reaction for 7-10 hours, and distilled under reduced pressure. The product was added into ether for precipitation, filtered and dried to obtain fluorinated modified polyethylene glycol.

[0007] Step (2), fluorine-containing modified polyethylene glycol, diisocyanate (structural formula OCN-R-NCO), and dibutyltin dilaurate are mixed, heated to 70-80°C in a nitrogen atmosphere, and reacted for 2-3 hours. The product is added to ether for precipitation, filtered, and dried to obtain an isocyanate-terminated fluorine-containing polyurethane prepolymer. The reaction formula is:

[0008]

[0009] Step (3), mixing butyl acetate solvent, hydroxyl acrylic resin, and terminal isocyanate fluorinated polyurethane prepolymer to obtain a weather-resistant environmentally friendly adhesive.

[0010] Preferably, in step (1), the ratio of polyethylene glycol diglycidyl ether, perfluoroalkyl alcohol, and boron trifluoride ether is 1 mol: (2-2.2) mol: (36-44) mL. The molecular formula of perfluoroalkyl alcohol is CF3(CF2) n CH2OH, n is any integer from 3 to 6.

[0011] Preferably, in step (2), the ratio of fluorinated modified polyethylene glycol, diisocyanate, and dibutyltin dilaurate is 1 mol: (2.6-2.8) mol: (1.6-2) mmol. The diisocyanate is isophorone diisocyanate, toluene-2,4-diisocyanate, or 4,4'-methylenebis(phenyl isocyanate).

[0012] Preferably, in step (3), the ratio of hydroxyl acrylic resin to isocyanate-terminated fluorinated polyurethane prepolymer is 100 g:(10-25) g.

[0013] The technical effect of the present invention is as follows: using boron trifluoride ether as a catalyst, polyethylene glycol diglycidyl ether and perfluoroalkyl alcohol are reacted to obtain fluorine-containing modified polyethylene glycol, which is then reacted with diisocyanate to obtain terminal isocyanate fluorine-containing polyurethane prepolymer, which is used as a curing modifier and added to a hydroxy acrylic resin. The double-terminal isocyanate groups of the polyurethane prepolymer undergo a cross-linking curing reaction with the hydroxyl groups of the acrylic resin, thereby enhancing the cohesive force of the acrylic resin, thereby improving the tensile shear strength and bonding performance of the adhesive, and the polyurethane prepolymer contains a water-resistant and heat-resistant perfluoroalkyl chain, which is introduced into the acrylic resin curing network, which is beneficial to improving the wet heat aging resistance and weather resistance of the adhesive. After the wet heat aging test, the adhesive still maintains good tensile shear strength. DETAILED DESCRIPTION

[0014] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0015] The following hydroxylated acrylic resin model AC-166K was purchased from Shanghai Qizhan New Material Technology Co., Ltd. Polyethylene glycol diglycidyl ether with a molecular weight of 1000 was purchased from Wuhan Lanabai Pharmaceutical Chemical Co., Ltd.

[0016] Embodiment 1:

[0017] Step (1), add 5 mmol of polyethylene glycol diglycidyl ether, 10 mmol of undecylfluoro-n-hexane-1-ol (structural formula) to 15 mL of 1,4-dioxane. CAS registration number 423-46-1), heated to 80°C, added 0.22 mL of boron trifluoride etherate, stirred for 10 h, distilled under reduced pressure, the product was added to ether for precipitation, filtered and dried to obtain fluorinated modified polyethylene glycol.

[0018] Step (2), 5 mmol of fluorine-modified polyethylene glycol, 13 mmol of toluene-2,4-diisocyanate, and 0.01 mmol of dibutyltin dilaurate are mixed, heated to 75° C. in a nitrogen atmosphere, and reacted for 3 hours. The product is added to ether for precipitation, filtered, and dried to obtain an isocyanate-terminated fluorine-containing polyurethane prepolymer.

[0019] Step (3), 60 mL of butyl acetate solvent, 100 g of hydroxyl acrylic resin, and 10 g of terminal isocyanate fluorinated polyurethane prepolymer are mixed to obtain a weather-resistant environmentally friendly adhesive.

[0020] Embodiment 2:

[0021] Step (1), add 5 mmol of polyethylene glycol diglycidyl ether and 11 mmol of pentadecafluorooctan-1-ol (structural formula) to 15 mL of 1,4-dioxane. CAS registration number 307-30-2), heated to 90°C, added 0.18 mL of boron trifluoride etherate, stirred for 10 h, distilled under reduced pressure, the product was added to ether for precipitation, filtered and dried to obtain fluorinated modified polyethylene glycol.

[0022] Step (2), 5 mmol of fluorine-modified polyethylene glycol, 14 mmol of 4,4'-methylenebis(phenyl isocyanate) and 0.008 mmol of dibutyltin dilaurate are mixed, heated to 80°C in a nitrogen atmosphere, and reacted for 2 hours. The product is added to ether for precipitation, filtered and dried to obtain an isocyanate-terminated fluorine-containing polyurethane prepolymer.

[0023] Step (3), 60 mL of butyl acetate solvent, 100 g of hydroxyl acrylic resin, and 10 g of terminal isocyanate fluorinated polyurethane prepolymer are mixed to obtain a weather-resistant environmentally friendly adhesive.

[0024] Embodiment 3:

[0025] Step (1), add 5 mmol of polyethylene glycol diglycidyl ether and 10 mmol of nonafluoro-1-pentanol (structural formula) to 12 mL of 1,4-dioxane. CAS registration number 375-01-9), heated to 95°C, added 0.2 mL of boron trifluoride etherate, stirred for 7 h, distilled under reduced pressure, the product was added to ether for precipitation, filtered and dried to obtain fluorinated modified polyethylene glycol.

[0026] Step (2), 5 mmol of fluorine-modified polyethylene glycol, 13.6 mmol of isophorone diisocyanate, and 0.01 mmol of dibutyltin dilaurate are mixed, heated to 70° C. in a nitrogen atmosphere, and reacted for 3 h. The product is added to ether for precipitation, filtered, and dried to obtain an isocyanate-terminated fluorine-containing polyurethane prepolymer.

[0027] Step (3), 60 mL of butyl acetate solvent, 100 g of hydroxyl acrylic resin, and 10 g of terminal isocyanate fluorinated polyurethane prepolymer are mixed to obtain a weather-resistant environmentally friendly adhesive.

[0028] Embodiment 4:

[0029] Step (1), 70 mL of butyl acetate solvent, 100 g of hydroxyl acrylic resin, and 15 g of terminal isocyanate fluorinated polyurethane prepolymer (prepared in the same manner as in Example 1) are mixed to obtain a weather-resistant environmentally friendly adhesive.

[0030] Embodiment 5:

[0031] Step (1), 80 mL of butyl acetate solvent, 100 g of hydroxyl acrylic resin, and 20 g of terminal isocyanate fluorinated polyurethane prepolymer (prepared in the same manner as in Example 1) are mixed to obtain a weather-resistant environmentally friendly adhesive.

[0032] Embodiment 6:

[0033] Step (1), 80 mL of butyl acetate solvent, 100 g of hydroxyl acrylic resin, and 25 g of terminal isocyanate fluorinated polyurethane prepolymer (prepared in the same manner as in Example 1) are mixed to obtain a weather-resistant environmentally friendly adhesive.

[0034] Comparative Example 1:

[0035] Step (1), 5 mmol polyethylene glycol 1000, 13 mmol toluene-2,4-diisocyanate, and 0.01 mmol dibutyltin dilaurate are mixed, heated to 75° C. in a nitrogen atmosphere, and reacted for 3 hours. The product is added to ether for precipitation, filtered, and dried to obtain an isocyanate-terminated polyurethane prepolymer.

[0036] Step (2), 60 mL of butyl acetate solvent, 100 g of hydroxyl acrylic resin, and 10 g of terminal isocyanate polyurethane prepolymer are mixed to obtain an adhesive.

[0037] Comparative Example 2:

[0038] Step (1), 60 mL of butyl acetate solvent, 100 g of hydroxy acrylic resin, and 10 g of fluorine-modified polyethylene glycol (prepared in the same manner as in Example 1) are mixed to obtain an adhesive.

[0039] The adhesive was coated between two steel specimens, cured at 70°C for 6 hours, and placed at room temperature for 24 hours. The tensile shear strength of the adhesive was tested according to GB / T7124-2008 standard.

[0040] The steel sheet sample coated with adhesive was placed in a constant temperature and humidity test chamber, with the temperature controlled at 80°C and the relative humidity at 85%, and subjected to wet heat aging for 360 hours. Then the tensile shear strength test was performed.

[0041] Table 1: Test results

[0042]

[0043] After testing, it was found that terminal isocyanate polyurethane prepolymer was added to the hydroxyl acrylic resin of Examples 1-6, and its double-ended isocyanate groups underwent cross-linking and curing reaction with the hydroxyl groups of the acrylic resin, thereby improving the cohesion of the acrylic resin and significantly improving the tensile shear strength and bonding properties of the adhesive. In addition, the polyurethane prepolymer contained a water-resistant and heat-resistant perfluoroalkyl chain, which was introduced into the acrylic resin curing network, which was beneficial to improving the moisture-heat aging resistance and weather resistance of the adhesive.

[0044] In Comparative Example 1, a cross-linking curing reaction is carried out between a terminal isocyanate polyurethane prepolymer and a hydroxyl acrylic resin. The tensile shear strength of the adhesive is relatively large. However, the polyurethane prepolymer does not contain a perfluoroalkyl chain. After a wet heat aging test, the retention rate of the tensile shear strength of the adhesive is low, and the wet heat aging resistance and weather resistance of the adhesive cannot be effectively improved.

[0045] The fluorinated modified polyethylene glycol in Comparative Example 2 does not contain an isocyanate group and cannot undergo a cross-linking and curing reaction with the hydroxy acrylic resin. The perfluoroalkyl chain is also not introduced into the acrylic resin structure, resulting in poor tensile shear strength and bonding properties of the adhesive, as well as poor resistance to moisture and heat aging and weathering.

Claims

1. A method for preparing a weather-resistant environmentally friendly adhesive, characterized in that: The preparation method is: Step (1), adding polyethylene glycol diglycidyl ether and perfluoroalkyl alcohol to 1,4-dioxane, heating to the reaction temperature, dropping boron trifluoride etherate, distilling under reduced pressure after the reaction, filtering and drying after precipitation to obtain fluorine-containing modified polyethylene glycol; Step (2), mixing fluorine-containing modified polyethylene glycol, diisocyanate and dibutyltin dilaurate, heating to a reaction temperature in a nitrogen atmosphere, precipitating the product after the reaction, filtering and drying to obtain an isocyanate-terminated fluorine-containing polyurethane prepolymer; Step (3), mixing butyl acetate solvent, hydroxyl acrylic resin, and terminal isocyanate fluorinated polyurethane prepolymer to obtain a weather-resistant environmentally friendly adhesive.

2. The method for preparing the weather-resistant environmentally friendly adhesive according to claim 1, characterized in that: In the step (1), the ratio of polyethylene glycol diglycidyl ether, perfluoroalkyl alcohol and boron trifluoride ether is 1 mol: (2-2.2) mol: (36-44) mL.

3. The method for preparing the weather-resistant environmentally friendly adhesive according to claim 2, characterized in that: The molecular formula of the perfluoroalkyl alcohol is CF3(CF2) n CH2OH, n is any integer from 3 to 6.

4. The method for preparing the weather-resistant environmentally friendly adhesive according to claim 1, characterized in that: The reaction temperature in step (1) is 80-95° C. and the reaction time is 7-10 h.

5. The method for preparing the weather-resistant environmentally friendly adhesive according to claim 1, characterized in that: In the step (2), the ratio of fluorine-containing modified polyethylene glycol, diisocyanate and dibutyltin dilaurate is 1 mol: (2.6-2.8) mol: (1.6-2) mmol.

6. The method for preparing the weather-resistant environmentally friendly adhesive according to claim 5, characterized in that: The diisocyanate is isophorone diisocyanate, toluene-2,4-diisocyanate or 4,4'-methylenebis(phenyl isocyanate).

7. The method for preparing the weather-resistant environmentally friendly adhesive according to claim 1, characterized in that: In the step (2), the reaction temperature is 70-80° C. and the reaction time is 2-3 h.

8. The method for preparing the weather-resistant environmentally friendly adhesive according to claim 1, characterized in that: In the step (3), the ratio of the hydroxy acrylic resin to the isocyanate-terminated fluorinated polyurethane prepolymer is 100 g:(10-25) g.

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