Preparation method of high-weather-resistance polyurethane adhesive capable of being rapidly cured

Abstract

The invention relates to the technical field of adhesive preparation, in particular to a preparation method of a high-weather-resistance polyurethane adhesive capable of being rapidly cured, the high-weather-resistance polyurethane adhesive comprises an adhesive a and an adhesive b, and the high-weather-resistance polyurethane adhesive is prepared through the following steps: S1, preparing a mixture a, S2, preparing the adhesive a, and S3, preparing the adhesive b; a cross-linked network structure can be formed in the rapid curing process by selecting a proper dosage of cross-linking agent, so that the adhesive has higher bonding strength, and the tensile strength and the initial strength of the structural adhesive can be improved; mixing the prepolymer, the isocyanate tripolymer, the water removal agent, the plasticizer and the filler through a static mixer to obtain an adhesive b; by controlling the selection method of the prepolymer and controlling the use amount of the isocyanate tripolymer, the bonding strength of the structural adhesive to a base material can be remarkably improved, so that the adhesive is firmer, the weather resistance of the adhesive is better, and good performance can be kept in a severe environment.

Description

Technical Field

[0001] The invention relates to the technical field of adhesive preparation, and in particular to a method for preparing a fast-curing highly weather-resistant polyurethane adhesive. Background Art

[0002] Polyurethane adhesives are an important type of industrial adhesives, which are widely used in many fields such as automobiles, construction, and electronics due to their excellent bonding and mechanical properties. Polyurethane adhesives are mainly synthesized by the reaction of raw materials such as isocyanates, polyols, and additives. Their molecular chains contain carbamate groups or isocyanate groups, which makes polyurethane adhesives highly chemically active and can form strong chemical bonds with a variety of materials.

[0003] Two-component polyurethane adhesives have attracted much attention due to their excellent bonding properties and wide range of applications. This type of adhesive is usually made by mixing two components, which contain isocyanate groups and hydroxyl groups respectively, and they undergo a chemical reaction after mixing and cure quickly.

[0004] In recent years, with the rapid development of industrial production, the demand for fast-curing, highly weather-resistant two-component polyurethane adhesives has been growing. Fast curing technology is of great significance for improving production efficiency and reducing costs. Traditional two-component polyurethane adhesives have a long curing time, and the existing traditional two-component polyurethane adhesives still have insufficient weather resistance, which makes it difficult to meet the requirements of long-term outdoor use. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a method for preparing a fast-curing and highly weather-resistant polyurethane adhesive.

[0006] The technical scheme of the present invention is: a method for preparing a fast-curing highly weather-resistant polyurethane adhesive, wherein the highly weather-resistant polyurethane adhesive comprises an adhesive a and an adhesive b, wherein the mass ratio of the adhesive a to the adhesive b is 1:0.8-1.2, and the two are stored separately and mixed when used;

[0007] The preparation method of the highly weather-resistant polyurethane adhesive comprises the following steps:

[0008] S1. Preparation of mixture a

[0009] By mass percentage, 18-35% of polyester polyol, 10-25% of polyether polyol, 1-8% of crosslinking agent, 0.1-6% of D-230 and the balance of polybutadiene polyol are put into a reaction kettle, the vacuum environment is evacuated, and the mixture is stirred and mixed at a temperature of 110-140° C. for 3-8 hours to obtain a mixture a;

[0010] S2. Preparation of adhesive a

[0011] The temperature is lowered to 20-50° C., and 10-25% of filler, 2-15% of thickener, 0.01-0.6% of catalyst, 1-3% of 3-aminopropyltriethoxysilane, 0-2% of γ-mercaptopropyltriethoxysilane, and 1-6% of molecular sieve are added to the mixture a in sequence, and the mixture is stirred evenly under vacuum to obtain an adhesive a.

[0012] S3. Preparation of adhesive b

[0013] By mass percentage, 30-60% of prepolymer, 0.1-10% of isocyanate trimer, 1-8% of dehydrating agent, 1-10% of plasticizer and the remaining filler are mixed uniformly in a static mixer under vacuum environment to obtain adhesive b.

[0014] Note: Stirring in a vacuum environment helps to remove bubbles from the mixture, promote the smooth progress of chemical reactions, and improve the overall quality of the product; the addition of silane coupling agent and molecular sieve can improve the curing characteristics of the adhesive, making it more uniform and stable; by adjusting the use of adhesives a and b through this ratio, the hardness, flexibility and bonding strength of the final product can be controlled to meet different application requirements, ensure the curing speed, and reduce material waste.

[0015] Furthermore, the cross-linking agent is one or more combinations of 1,4-butanediol, 1,6-hexanediol, trimethylolpropane, 1,4-cyclohexanedimethanol, and diethylaminoethanol.

[0016] Description: Cross-linking agents can react with hydroxyl or amino groups on the polyurethane molecular chain to form chemical bonds, thereby increasing the cohesive strength and bonding strength of the polyurethane; through cross-linking reactions, a tighter network structure can be formed to reduce moisture entry, thereby improving the water resistance of the polyurethane adhesive; different cross-linking agents have different reactivity and can adjust the curing speed.

[0017] Furthermore, the mixture a also includes auxiliary agents, which include 0.1-6% T31, 0.2-5% plasticizer, 0.1-1% ultraviolet absorber, 0.1-0.2% antibacterial agent, 0.5-2% antioxidant, 0.2-2% triethylene glycol, 0.1-1% neopentyl glycol and 0.1-0.5% pentaerythritol, accounting for 0.1-6% of the mass of the mixture a.

[0018] Description: Plasticizers can improve the flexibility and ductility of adhesives, so that the adhesives can still maintain good performance at low temperatures and improve the weather resistance of adhesives; UV absorbers can protect adhesives from degradation caused by ultraviolet radiation and extend the service life of the product; antibacterial agents help inhibit the growth of microorganisms, prevent adhesives from deteriorating due to bacterial contamination, and keep adhesives clean and hygienic; triethylene glycol, as a polyol, can participate in the synthesis reaction of polyurethane, and can also act as a plasticizer to improve the performance of adhesives and enhance the adhesive's resistance to low temperatures; adding neopentyl glycol can improve the flexibility and heat resistance of the adhesive, and the curing efficiency can be improved by an appropriate amount of T31. Adding an appropriate amount of pentaerythritol can improve the heat resistance and weather resistance of the adhesive.

[0019] Furthermore, the plasticizer is one or any combination of alkyl phthalate, diisononyl 1,2-cyclohexanedicarboxylate, dioctyl carbonate and BENZOFLEX 9-88SG; the ultraviolet absorber is UV-1; the antibacterial agent is an inorganic antibacterial agent; the antioxidant is one or any combination of antioxidant-1010, antioxidant-1076 and TNP.

[0020] Description: By adding appropriate amounts of alkyl phthalates, diisononyl 1,2-cyclohexanedicarboxylate, dioctyl carbonate and BENZOFLEX 9-88SG, the flexibility and ductility of the adhesive can be increased, making it more elastic and plastic, thereby enhancing the bonding performance. The addition of appropriate plasticizers can limit the sagging phenomenon during the substrate assembly bonding process, while providing increased thermal conductivity and improving heat dissipation performance.

[0021] Furthermore, the filler is one or any combination of light calcium carbonate, zelide powder, zinc white, montmorillonite, cellulose nanocrystals and silicon dioxide.

[0022] Description: By adding fillers, the hardness, compression resistance and impact resistance of polyurethane adhesives can be enhanced, thereby improving their overall mechanical properties; silica and other materials can improve the chemical resistance of polyurethane adhesives, making them perform better in harsh environments; zelide powder and zinc white can optimize the adhesion and peeling force of two-component polyurethane adhesives, and improve their bonding strength and tensile properties; light calcium carbonate can improve the heat resistance and cold resistance of adhesives; cellulose nanocrystals, due to their high strength and good flexibility, can improve the mechanical properties of adhesives without affecting transparency; at the same time, increase their bonding strength and wear resistance; montmorillonite and zinc white can improve the bonding strength and weather resistance of adhesives.

[0023] Furthermore, the prepolymer in step S3 is a DETDA type PRA prepolymer, and the isocyanate content thereof is 10-20%.

[0024] Description: Using DETDA type PRA prepolymer can accelerate the curing speed of polyurethane adhesive, shorten its gel and surface drying time, and enhance the tensile strength of polyurethane adhesive.

[0025] Furthermore, the prepolymer in step S3 adopts a grafted prepolymer, and its preparation method is as follows: nitrogen protection is applied, dehydrated castor oil is introduced into a dripping device at a temperature of 70 to 75° C., liquefied MDI is dripped in equal amounts in batches, the molar ratio of liquefied MDI to dehydrated castor oil is controlled to be 1:0.4 to 0.6, the titration rate is 20 to 35 min / time, the reaction is performed for 3 to 4 hours, and a PU prepolymer is obtained. Subsequently, the temperature is raised to 75 to 85° C., and 0.01 to 0.02% of E-51, 0.01 to 0.02% of DBTDL, 1 to 15% of an active diluent, and 0.03 to 0.35% of DEG, which account for 0.01 to 0.02% of the total mass of the prepolymer, are added to the PU prepolymer, and the mixture is stirred and mixed for 1 to 5 hours to obtain a grafted prepolymer.

[0026] Description: PU prepolymer is prepared by dehydrated castor oil and liquefied MDI, and then E-51 is grafted to form an IPN structure polymer. Through epoxy groups and hydroxyl polar groups, the cured two-component polyurethane adhesive has excellent bonding ability to metal substrates; the epoxy group end-capping prolongs the storage life of adhesive b and improves its weather resistance; the benzene ring can provide heat resistance and rigidity to the cured adhesive; the isopropyl group generated during the synthesis of the polyurethane prepolymer improves the alkali resistance of E-51, and by mixing with adhesive a, the overall flexibility and weather resistance of the two-component polyurethane adhesive are improved; adding appropriate DEG can improve the bonding strength of the polyurethane adhesive, improve its water resistance and surface hardness.

[0027] Furthermore, the active diluent is one or any combination of propylene oxide butyl ether, propylene oxide benzyl ether and dodecyl glycidyl ether.

[0028] Description: By selecting different active diluents, the curing time of polyurethane adhesive can be controlled, the viscosity of polyurethane adhesive can be reduced, and the adhesive can show better fluidity during mixing and construction, making it easier to operate and improving the bonding ability to plastic substrates such as nylon and ABS. The use of propylene oxide butyl ether, propylene oxide benzyl ether and dodecyl glycidyl ether can improve its flexibility and impact resistance in low temperature environments.

[0029] The beneficial effects of the present invention are:

[0030] The invention adopts a cross-linking network structure formed by selecting a suitable amount of cross-linking agent in a rapid curing process, so that the adhesive has higher bonding strength and can improve the tensile strength and initial strength of the structural adhesive; the addition of fillers can enhance the mechanical properties of the adhesive and improve its compressive, tensile and flexural strengths; the prepolymer, isocyanate trimer, dehydrating agent, plasticizer and filler are mixed by a static mixer to obtain adhesive B; controlling the amount of isocyanate trimer can significantly improve the bonding strength of the structural adhesive to the substrate, making the adhesive stronger; the two-component adhesive prepared by the method has high initial strength and can be used in large-scale automated production; the adhesive has high elasticity after curing and can improve the elongation of the adhesive after curing; the mixed use of the auxiliary agent, filler and plasticizer can maintain the functional effect before use, facilitate transportation and storage, and improve the weather resistance of the adhesive during use, so that it can maintain good performance even in harsh environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a bar graph of tensile strength properties of Examples 1 to 14 of the present invention and Comparative Examples 1 and 2;

[0032] Figure 2 is a bar graph of heat resistance and viscosity properties of Examples 1 to 14 of the present invention and Comparative Examples 1 and 2;

[0033] Figure 3 It is a bar graph of the curing speed performance tested under condition 1 of Examples 1, 4 to 14 of the present invention and Comparative Examples 1 and 2;

[0034] Figure 4 It is a bar graph of the curing speed performance tested under condition 2 for Examples 1, 4 to 14 of the present invention and Comparative Examples 1 and 2. DETAILED DESCRIPTION

[0035] In order to further illustrate the method adopted by the present invention and the effect achieved, the technical solution of the present invention will be clearly and completely described in combination with experiments below.

[0036] Example 1: A method for preparing a fast-curing highly weather-resistant polyurethane adhesive, wherein the highly weather-resistant polyurethane adhesive comprises an adhesive a and an adhesive b, wherein the mass ratio of the adhesive a to the adhesive b is 1:1, and the two are stored separately and mixed when used;

[0037] The preparation method of the highly weather-resistant polyurethane adhesive comprises the following steps:

[0038] S1. Preparation of mixture a

[0039] By mass percentage, 26.5% of polyester polyol, 17.5% of polyether polyol, 4.5% of crosslinking agent, 3% of D-230, 15.85% of auxiliary agent and the balance of polybutadiene polyol were put into a reaction kettle, vacuumed, stirred and mixed at a temperature of 125° C. for 5.5 hours to obtain a mixture a;

[0040] The cross-linking agent is a mixture of 1,4-butanediol, 1,6-hexanediol and trimethylolpropane in equal mass ratios;

[0041] The auxiliary agent includes 3% T31, 2.7% plasticizer, 0.55% ultraviolet absorber, 0.15% antibacterial agent, 8% antioxidant, 0.6% triethylene glycol, 0.55% neopentyl glycol and 0.3% pentaerythritol, accounting for 3% of the mass of the mixture a;

[0042] The plasticizer is a mixture of alkyl phthalate and diisononyl 1,2-cyclohexanedicarboxylate in equal weight ratios; the ultraviolet absorber is UV-1; the antibacterial agent is an inorganic antibacterial agent; and the antioxidant is antioxidant-1010;

[0043] S2. Preparation of adhesive a

[0044] The temperature is lowered to 35° C., 17.5% of filler, 8.5% of thickener, 0.3% of catalyst, 2% of 3-aminopropyltriethoxysilane, 1% of γ-mercaptopropyltriethoxysilane, and 3.5% of molecular sieve are added to the mixture a in sequence, and the mixture is stirred evenly under a vacuum environment to obtain an adhesive a; the filler is light calcium carbonate, zelide powder, montmorillonite, and cellulose nanocrystals mixed in equal proportions by volume;

[0045] S3. Preparation of adhesive b

[0046] By mass percentage, 45% of the prepolymer, 0.1% of the isocyanate trimer, 4.5% of the dehydrating agent, 5% of the plasticizer and the remaining filler were mixed uniformly in a static mixer under vacuum to obtain an adhesive b.

[0047] The prepolymer is a grafted prepolymer, and its preparation method is as follows: nitrogen is filled for protection, dehydrated castor oil is introduced into a dripping device at a temperature of 72.5°C, liquefied MDI is dripped in equal amounts in batches, the molar ratio of liquefied MDI to dehydrated castor oil is 1:0.5, the titration rate is 27.5min / time, the reaction is carried out for 3.5h, a PU prepolymer is obtained, and then the temperature is raised to 80°C, 0.015% of E-51, 0.015% of DBTDL, 8% of active diluent and 0.0325% of DEG accounting for the total mass of the prepolymer are added to the PU prepolymer, and the mixture is stirred and mixed for 3h to obtain a grafted prepolymer; the active diluent is propylene oxide butyl ether.

[0048] Example 2: This example is basically the same as Example 1, except that 18% of polyester polyol, 10% of polyether polyol, 1% of cross-linking agent, 0.1% of D-230, 15.85% of auxiliary agent and the remainder of polybutadiene polyol are put into a reaction kettle, the vacuum environment is evacuated, and the mixture is stirred and mixed at a temperature of 110°C for 3 hours to obtain a mixture a.

[0049] Example 3: This example is basically the same as Example 1, except that 35% of polyester polyol, 25% of polyether polyol, 8% of cross-linking agent, 6% of D-230, 15.85% of auxiliary agent and the remainder of polybutadiene polyol are put into a reaction kettle, the vacuum environment is evacuated, and the mixture is stirred and mixed at a temperature of 140°C for 8 hours to obtain a mixture a.

[0050] Example 4: This example is basically the same as Example 1, except that the temperature is lowered to 20°C, 10% of filler, 2% of thickener, 0.01% of catalyst, 1% of 3-aminopropyltriethoxysilane, and 1% of molecular sieves accounting for the total mass of mixture a are added to mixture a in sequence, and the mixture is stirred evenly under a vacuum environment to obtain adhesive a.

[0051] Example 5: This example is basically the same as Example 1, except that the temperature is lowered to 50°C, 25% of filler, 15% of thickener, 0.6% of catalyst, 3% of 3-aminopropyltriethoxysilane, 2% of γ-mercaptopropyltriethoxysilane, and 6% of molecular sieves accounting for the total mass of mixture a are added to mixture a in sequence, and the mixture is stirred evenly under a vacuum environment to obtain adhesive a.

[0052] Example 6: This example is basically the same as Example 1, except that 30% of the prepolymer, 5% of the isocyanate trimer, 1% of the dehydrating agent, 1% of the plasticizer and the remaining filler are mixed evenly by a static mixer under a vacuum environment to obtain adhesive b.

[0053] Example 7: This example is basically the same as Example 1, except that 30-60% of the prepolymer, 10% of the isocyanate trimer, 8% of the dehydrating agent, 10% of the plasticizer and the remaining filler are mixed evenly by a static mixer under a vacuum environment to obtain adhesive b.

[0054] Example 8: This example is basically the same as Example 1, except that the dosage of the auxiliary agent added is changed, including 0.1% T31, 0.2% plasticizer, 0.1% UV absorber, 0.1% antibacterial agent, 0.5% antioxidant, 0.2% triethylene glycol, 0.1% neopentyl glycol and 0.1% pentaerythritol, accounting for 0.1% of the mass of the mixture a.

[0055] Example 9: This example is basically the same as Example 1, except that the dosage of the auxiliary agent added is changed, including 6% T31, 5% plasticizer, 1% UV absorber, 0.2% antibacterial agent, 2% antioxidant, 2% triethylene glycol, 1% neopentyl glycol and 0.5% pentaerythritol, accounting for 6% of the mass of mixture a.

[0056] Example 10: This example is basically the same as Example 1, except that dehydrated castor oil is introduced into a dripping device at a temperature of 70°C, and liquefied MDI is dripped in equal amounts in batches, the molar ratio of liquefied MDI to dehydrated castor oil is 1:0.4, the titration rate is 20 min / time, and the reaction is carried out for 3 hours to obtain a PU prepolymer. Subsequently, the temperature is raised to 75°C, and 0.01% of E-51, 0.01% of DBTDL, 1% of an active diluent and 0.03% of DEG, which account for the total mass of the prepolymer, are added to the PU prepolymer, and the mixture is stirred and mixed for 1 hour to obtain a grafted prepolymer.

[0057] Example 11: This example is basically the same as Example 1, except that dehydrated castor oil is introduced into a dripping device at a temperature of 75°C, and liquefied MDI is dripped in equal amounts in batches, the molar ratio of liquefied MDI to dehydrated castor oil is 1:0.6, the titration rate is 35 min / time, the reaction is carried out for 4 hours, and a PU prepolymer is obtained. Subsequently, the temperature is raised to 85°C, and 0.02% of E-51, 0.02% of DBTDL, 15% of active diluent and 0.35% of DEG, which account for 0.02% of the total mass of the prepolymer, are added to the PU prepolymer, and the mixture is stirred and mixed for 5 hours to obtain a grafted prepolymer.

[0058] Example 12: This example is basically the same as Example 1, except that 30% of the prepolymer, 0.1% of the isocyanate trimer, 1% of the dehydrating agent, 1% of the plasticizer and the remaining filler are mixed uniformly by a static mixer under a vacuum environment to obtain an adhesive b; the prepolymer adopts a DETDA type PRA prepolymer, and its isocyanate group content is 10%.

[0059] Example 13: This example is basically the same as Example 1, except that 45% of the prepolymer, 5% of the isocyanate trimer, 4.5% of the dehydrating agent, 5% of the plasticizer and the remaining filler are mixed evenly by a static mixer under a vacuum environment to obtain an adhesive b; the prepolymer adopts a DETDA type PRA prepolymer, and its isocyanate group content is 15%.

[0060] Example 14: This example is basically the same as Example 1, except that 60% of the prepolymer, 10% of the isocyanate trimer, 8% of the dehydrating agent, 10% of the plasticizer and the remaining filler are mixed uniformly by a static mixer under a vacuum environment to obtain an adhesive b; the prepolymer adopts a DETDA type PRA prepolymer, and its isocyanate group content is 20%.

[0061] Example 15: This example is basically the same as Example 1, except that the mass ratio of adhesive a to adhesive b is 1:0.8, and the two are stored separately and mixed when used.

[0062] Example 16: This example is basically the same as Example 1, except that the mass ratio of adhesive a to adhesive b is 1:1.2, and the two are stored separately and mixed when used.

[0063] Control Example 1: With reference to Example 1, adhesive b is prepared by mixing a conventional polyurethane prepolymer having an NCO content of 15% with conventional filler calcium carbonate in a mass ratio of 2:1, wherein the conventional polyurethane prepolymer is prepared by reacting isophorone diisocyanate and polyether diol.

[0064] Comparative Example 2: Using Example 1 as a reference, no auxiliary agent was added to the mixture a.

[0065] Experimental Example: In order to explore the performance of the polyurethane adhesive produced in each embodiment and control example, the main raw materials were determined according to the experimental formula, and the samples were weighed and tested. The tensile strength was tested according to the standard GB / T 528-2009; the viscosity of the polyurethane adhesive was tested according to GB / T2794-2013, and the thermal stability of the polyurethane adhesive was tested according to GB / T 16998-1997; other properties were tested according to conventional methods, and the specific exploration is as follows:

[0066] Figure 3 , 4 Condition 1 is: the sample is coated on the substrate and then allowed to stand for 15 minutes before testing; Condition 2 is: the sample is coated on the substrate and then allowed to stand for 36 hours before testing.

[0067] 1. Explore the influence of specific preparation methods of polymers on the performance of polyurethane adhesives:

[0068] like Figures 1 to 4As shown, by comparing Examples 1 and 10 to 14, it can be seen that Example 1 has the highest tensile strength and heat resistance temperature, Example 13 has the best viscosity but the tensile strength and heat resistance are slightly lower than Example 1, the two-component adhesive prepared by the method of Example 1 is the best, and the tensile strength of Example 11 is better than that of Example 10. It can be seen that the strength performance of the two-component adhesive prepared by the polymer using the process parameters of Example 11 is better, and Example 13 is better than Examples 12 and 14. The strength performance of the two-component adhesive prepared by its method is slightly lower than that of Example 1. It can be seen that the two methods for selecting prepolymers in this scheme have their own advantages. Figure 3 , 4 It can be seen that there is no obvious difference in the heat resistance and viscosity of the samples over time, and the two-component adhesive prepared in this scheme has good weather resistance.

[0069] 2. Investigate the effect of the ratio of mixture a on the performance of polyurethane adhesive:

[0070] like Figures 1 to 3 As shown, by comparing Examples 1, 2, and 3, it can be seen that Example 3 has the highest tensile strength, but the lowest heat resistance temperature, Example 2 has the best heat resistance, and the viscosity difference among Examples 1, 2, and 3 is not obvious, among which the two-component adhesive prepared by the method of Example 1 has the best viscosity.

[0071] 3. Explore the influence of the ratio of adhesive a on the performance of polyurethane adhesive:

[0072] like Figures 1 to 4 As shown, by comparing Examples 1, 4, and 5, it can be seen that Example 1 has the highest tensile strength, Example 4 has the lowest heat resistance temperature, Example 1 has the best viscosity performance, and there are no obvious differences in viscosity and curing performance between Examples 4 and 5. Among them, the two-component adhesive prepared by the method of Example 1 has the best comprehensive performance.

[0073] 4. Explore the effect of the ratio of adhesive b on the performance of polyurethane adhesive:

[0074] like Figures 1 to 4 As shown, by comparing Examples 1, 6, 7 with Control Example 1, it can be seen that the difference in tensile strength of Examples 1, 6, 7 is not obvious, the tensile strength performance of Control Example 1 is much lower than that of Examples 1, 6, 7, the heat resistance temperature of Example 7 is the highest, the viscosity performance of Example 1 is the best, the viscosity of the two-component polyurethane adhesive prepared by the process parameters of Examples 6 and 7 is much lower than that of Example 1, the gel time and surface dry time of Control Example 1 are much higher than those of Examples 1, 6, 7, and the two-component adhesive prepared by the method of Example 6 cures the fastest.

[0075] 5. Explore the influence of the ratio of auxiliary agents on the performance of polyurethane adhesives:

[0076] like Figures 1 to 4 As shown, by comparing Examples 1, 8, and 9 with Control Example 2, it can be seen that Example 1 has the highest tensile strength, and the tensile strength performance of Control Example 2 is lower than that of Examples 1, 8, and 9. Example 1 has the highest heat resistance temperature, and Example 9 has the best viscosity performance. There is no obvious difference in the curing time of the two-component polyurethane adhesive prepared by the process parameters of Examples 1, 8, and 9. The gel time and surface dry time of Control Example 2 are much longer than those of Examples 1, 8, and 9. It can be seen that the ratio of the auxiliary agent has a certain influence on the curing performance of the polyurethane adhesive.

Claims

1. A method for preparing a fast-curing highly weather-resistant polyurethane adhesive, characterized in that: The highly weather-resistant polyurethane adhesive comprises adhesive a and adhesive b, the mass ratio of adhesive a to adhesive b is 1:0.8-1.2, the two are stored separately and mixed when used; The preparation method of the highly weather-resistant polyurethane adhesive comprises the following steps: S1. Preparation of mixture a By mass percentage, 18-35% of polyester polyol, 10-25% of polyether polyol, 1-8% of crosslinking agent, 0.1-6% of D-230 and the balance of polybutadiene polyol are put into a reaction kettle, the vacuum environment is evacuated, and the mixture is stirred and mixed at a temperature of 110-140° C. for 3-8 hours to obtain a mixture a; S2. Preparation of adhesive a The temperature is lowered to 20-50° C., and 10-25% of filler, 2-15% of thickener, 0.01-0.6% of catalyst, 1-3% of 3-aminopropyltriethoxysilane, 0-2% of γ-mercaptopropyltriethoxysilane, and 1-6% of molecular sieve are added to the mixture a in sequence, and the mixture is stirred evenly under vacuum to obtain an adhesive a. S3. Preparation of adhesive b By mass percentage, 30-60% of prepolymer, 0.1-10% of isocyanate trimer, 1-8% of dehydrating agent, 1-10% of plasticizer and the remaining filler are mixed uniformly in a static mixer under vacuum environment to obtain adhesive b.

2. The method for preparing a fast-curing highly weather-resistant polyurethane adhesive according to claim 1, characterized in that: In step S1, the cross-linking agent is one or more of 1,4-butanediol, 1,6-hexanediol, trimethylolpropane, 1,4-cyclohexanedimethanol, and diethylaminoethanol.

3. The method for preparing a fast curable highly weather-resistant polyurethane adhesive according to claim 1, characterized in that: In terms of mass percentage, the mixture a in step S1 also includes an auxiliary agent, which includes 0.1-6% T31, 0.2-5% plasticizer, 0.1-1% ultraviolet absorber, 0.1-0.2% antibacterial agent, 0.5-2% antioxidant, 0.2-2% triethylene glycol, 0.1-1% neopentyl glycol and 0.1-0.5% pentaerythritol, accounting for 0.1-6% of the mass of the mixture a.

4. The method for preparing a fast-curing highly weather-resistant polyurethane adhesive according to claim 3, characterized in that: The plasticizer is one or any combination of alkyl phthalate, diisononyl 1,2-cyclohexanedicarboxylate, dioctyl carbonate and BENZOFLEX 9-88SG; the ultraviolet absorber is UV-1; the antibacterial agent is an inorganic antibacterial agent; the antioxidant is one or any combination of antioxidant-1010, antioxidant-1076 and TNP.

5. The method for preparing a fast-curing highly weather-resistant polyurethane adhesive according to claim 1, characterized in that: The filler in step S2 is one or any combination of light calcium carbonate, zelide powder, zinc white, montmorillonite, cellulose nanocrystals and silicon dioxide.

6. The method for preparing a fast-curing highly weather-resistant polyurethane adhesive according to claim 1, characterized in that: The prepolymer in step S3 is a DETDA type PRA prepolymer, and the isocyanate content thereof is 10-20%.

7. The method for preparing a fast-curing highly weather-resistant polyurethane adhesive according to claim 1, characterized in that: The prepolymer in step S3 is a grafted prepolymer, and its preparation method is as follows: nitrogen protection is applied, dehydrated castor oil is introduced into a dripping device at a temperature of 70 to 75° C., liquefied MDI is dripped in equal amounts in batches, the molar ratio of liquefied MDI to dehydrated castor oil is 1:0.4 to 0.6, the titration rate is 20 to 35 min / time, the reaction is carried out for 3 to 4 hours, and a PU prepolymer is obtained. Subsequently, the temperature is raised to 75 to 85° C., 0.01 to 0.02% of E-51, 0.01 to 0.02% of DBTDL, 1 to 15% of an active diluent, and 0.03 to 0.35% of DEG, which account for 0.01 to 0.02% of the total mass of the prepolymer, are added to the PU prepolymer, and the mixture is stirred and mixed for 1 to 5 hours to obtain a grafted prepolymer.

8. The method for preparing a fast-curing highly weather-resistant polyurethane adhesive according to claim 8, characterized in that: The active diluent is one or a combination of propylene oxide butyl ether, propylene oxide benzyl ether and dodecyl glycidyl ether.

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