Functional pressure-sensitive adhesive based on polyurethane and production method thereof

Abstract

The invention belongs to the field of preparation of pressure-sensitive adhesives, and discloses a polyurethane-based functional pressure-sensitive adhesive and a production method thereof.The polyurethane-based functional pressure-sensitive adhesive is prepared from, by weight, 60-85 parts of modified polyurethane prepolymer, 0.1-1 part of stannous octoate, 20-30 parts of 1-4 butanediol, 10-14 parts of modified aluminum hydroxide, 3-5 parts of ammonium polyphosphate microcapsules, 0.01-0.5 part of defoaming agent and 0.01-0.2 part of wetting agent. The modified polyurethane prepolymer is a silane-terminated castor oil modified polyurethane prepolymer, the modified aluminum hydroxide is obtained by grafting a triazine derivative after in-situ growth of aluminum phosphate on the surface of aluminum hydroxide, and the ammonium polyphosphate microcapsule is obtained by modifying ammonium polyphosphate with melamine and then coating with polypyrrole. According to the flame-retardant pressure-sensitive adhesive disclosed by the invention, through a synergistic flame-retardant effect of compounding the modified aluminum hydroxide and the ammonium polyphosphate microcapsules, the flame-retardant property of the pressure-sensitive adhesive can be greatly improved, meanwhile, the total dosage of a flame retardant is also reduced, and the influence on the adhesive property of the pressure-sensitive adhesive is reduced.

Description

Technical Field

[0001] The invention belongs to the field of preparation of pressure-sensitive adhesives, and in particular relates to a functional pressure-sensitive adhesive based on polyurethane and a production method thereof. Background Art

[0002] Pressure-sensitive adhesive, also known as pressure-sensitive adhesive, is most commonly defined as: without the use of solvents, heat or other means, only light finger pressure can firmly bond to the surface of the adherend, playing a practical bonding role. At the same time, during the peeling process, there will be no surface contamination caused by pressure-sensitive adhesive residue on the surface of the adherend. Pressure-sensitive adhesive will not dry up for a long time, so it is also commonly known as self-adhesive. The pressure-sensitive performance of pressure-sensitive adhesive is a prominent feature that distinguishes it from other types of adhesives or other products. Pressure-sensitive adhesive products can be used alone as labels, tapes and protective films, such as self-adhesive envelopes, stamps or note paper, etc., and are widely used in many fields such as electronic insulation devices, military, medical, automobiles, and aircraft shells.

[0003] There are many types of pressure-sensitive adhesives, which can be divided into rubber pressure-sensitive adhesives, acrylate pressure-sensitive adhesives, silicone copolymer pressure-sensitive adhesives and polyurethane pressure-sensitive adhesives according to the different polymers used in the main components. Among them, the copolymerization of the flexible segment and the rigid segment in the polyurethane pressure-sensitive adhesive gives it the characteristics of microphase separation, which is characterized by wear resistance, low temperature resistance, oil resistance and vibration resistance. Because it contains amino, isocyanate, hydroxyl and urea groups, the polyurethane pressure-sensitive adhesive has good bonding properties for most materials. In addition, the polyurethane pressure-sensitive adhesive has good weather resistance and can be used repeatedly for a long time. At the same time, it has stable performance when used in conjunction with phosphorus additives and does not grow mold. However, the flame retardant properties of polyurethane pressure-sensitive adhesives are poor. In the technical fields of packaging, automobiles, electronics and electrical engineering, there are very high requirements for the flame retardant properties of pressure-sensitive adhesives, which limits the application of polyurethane pressure-sensitive adhesives. Summary of the invention

[0004] In order to solve the deficiencies mentioned in the above background technology, the purpose of the present invention is to provide a functional pressure-sensitive adhesive based on polyurethane and a production method thereof. The synergistic flame retardant effect of the compound of modified aluminum hydroxide and ammonium polyphosphate microcapsules can greatly improve the flame retardant properties of the pressure-sensitive adhesive, while also reducing the total amount of flame retardants used and reducing the impact on the bonding properties of the pressure-sensitive adhesive.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A functional pressure-sensitive adhesive based on polyurethane comprises the following raw materials in parts by weight: 60-85 parts of modified polyurethane prepolymer, 0.1-1 parts of stannous octoate, 20-30 parts of 1-4-butanediol, 10-14 parts of modified aluminum hydroxide, 3-5 parts of ammonium polyphosphate microcapsules, 0.01-0.5 parts of defoaming agent, and 0.01-0.2 parts of wetting agent;

[0007] The modified polyurethane prepolymer is a silane-terminated castor oil-modified polyurethane prepolymer, the modified aluminum hydroxide is obtained by in-situ growing aluminum phosphate on the surface of aluminum hydroxide and then grafting a triazine derivative, and the ammonium polyphosphate microcapsules are obtained by modifying ammonium polyphosphate with melamine and then coating it with polypyrrole.

[0008] More preferably, the defoaming agent is one or more of polyether modified silicone, mineral oil mixture, and modified polysiloxane emulsion.

[0009] More preferably, the wetting agent is one or more of alkyl sulfates, sulfonates, fatty acids, fatty acid ester sulfates, carboxylic acid soaps, and phosphates.

[0010] Further preferably, the preparation method of the modified polyurethane prepolymer comprises the following steps:

[0011] (1) In a closed reactor equipped with a stirrer, high-purity nitrogen protection, reflux condenser, and thermometer, first add isophor diisocyanate and polyether polyol, and react at 80-90° C. for 2-4 hours;

[0012] (2) cooling the temperature to 55-60° C., adding castor oil, and then heating the temperature to 90-95° C. to react for 1-3 hours to obtain a polyurethane prepolymer modified with castor oil having terminal isocyanate groups;

[0013] (3) 3-aminopropyltriethoxysilane is then added and reacted at 60-70° C. for 3-5 hours until no isocyanate groups are detected in the system, thereby modifying the polyurethane prepolymer.

[0014] More preferably, the molar ratio of isophor diisocyanate, polyether polyol and castor oil is 2-4:1:1, and the mass ratio of 3-aminopropyltriethoxysilane to isocyanate-terminated castor oil-modified polyurethane prepolymer is 3-4:1.

[0015] Further preferably, the preparation method of modified aluminum hydroxide comprises the following steps:

[0016] A. Add aluminum hydroxide powder into anhydrous ethanol and stir to disperse, then add phosphoric acid into the suspension, stir to react for 4 to 6 hours, filter, wash and dry the suspension after the reaction to obtain aluminum hydroxide powder coated with aluminum phosphate;

[0017] B. Add cyanuric chloride to tetrahydrofuran and triethylamine under nitrogen atmosphere, stir to dissolve cyanuric chloride, then uniformly add 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionohydrazide, react in an ice bath for 4-6 hours after the addition is completed, then add 3-aminopropyltriethoxysilane dropwise to the reaction system, raise the temperature to 60°C, and keep the temperature for 3-5 hours. After the reaction is completed, cool and filter to remove triethylamine hydrochloride, remove tetrahydrofuran by vacuum distillation, then add ethyl acetate, dry and filter, and vacuum distill the filtrate to obtain a triazine nitrile derivative;

[0018] C. Add aluminum hydroxide powder coated with aluminum phosphate to 95 vol% ethanol aqueous solution, ultrasonically disperse for 10 to 15 minutes, adjust the pH of the solution to 3 to 4 with hydrochloric acid aqueous solution, then slowly add the triazine derivative to the above dispersion, continue ultrasonic dispersion for 5 to 10 minutes, heat to 80°C and keep the reaction for 3 to 5 hours, filter after cooling, wash and dry to obtain modified aluminum hydroxide.

[0019] More preferably, the molar ratio of cyanuric chloride, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionylhydrazide and 3-aminopropyltriethoxysilane is 1:2:1-2.

[0020] Further preferably, the method for preparing ammonium polyphosphate microcapsules comprises the following steps:

[0021] a. Dissolve ammonium polyphosphate in 50 vol% ethanol aqueous solution, and disperse it ultrasonically at 50°C for 20 to 40 minutes. Then add melamine to the solution and continue to disperse it ultrasonically for 5 to 15 minutes.

[0022] b. Raise the temperature to 120°C, stir and react for 1-2 hours, lower the temperature to 90°C, continue to react for 2-3 hours, drop 3-glycidyloxypropyltriethoxysilane into the solution, react at 60°C for 1-2 hours to obtain modified ammonium polyphosphate;

[0023] c. Add pyrrole to the solution, disperse it ultrasonically at room temperature for 20 to 40 minutes, then slowly drop 8 to 10 wt% ferric chloride solution, stir and react for 8 to 12 hours, wash with water and ethanol for 3 to 5 times, filter and dry to obtain polypyrrole microcapsule modified ammonium polyphosphate.

[0024] More preferably, the mass ratio of ammonium polyphosphate, melamine and pyrrole is 10:1:0.5.

[0025] A production method of a functional pressure-sensitive adhesive based on polyurethane comprises the following steps: mixing a modified polyurethane prepolymer, stannous octoate and 1-4-butanediol, reacting at 55-60°C for 0.5-1h, adding modified aluminum hydroxide, ammonium polyphosphate microcapsules, a defoamer and a wetting agent, mixing evenly, and vacuum defoaming for 20-40min to obtain a functional pressure-sensitive adhesive based on polyurethane.

[0026] Beneficial effects of the present invention:

[0027] The present invention can greatly improve the flame retardant properties of pressure-sensitive adhesives through the synergistic flame retardant effect of modified aluminum hydroxide and ammonium polyphosphate microcapsules, while also reducing the total amount of flame retardants and reducing the impact on the adhesive properties of pressure-sensitive adhesives. The modified aluminum hydroxide is a triazine derivative grafted after aluminum phosphate is in situ grown on the surface of aluminum hydroxide, thereby improving the dispersion effect of aluminum hydroxide in the polymer matrix. Aluminum phosphate has excellent chemical stability and thermal oxidation resistance. At the same time, the P element in aluminum phosphate and the triazine derivative contain rich N and Si elements, which both have an inhibitory effect on the combustion of polymer materials, thereby further improving the flame retardant effect of aluminum hydroxide. The ammonium polyphosphate microcapsules are modified with melamine and then coated with polypyrrole, thereby improving the compatibility of ammonium polyphosphate with the polymer matrix. The hydrophobic properties of the coated ammonium polyphosphate are significantly improved, and it has better thermal stability and carbon-forming properties. In addition, the triazine derivative grafted on the surface of the modified aluminum hydroxide has a hindered phenol unit, which can also give the pressure-sensitive adhesive good aging resistance. DETAILED DESCRIPTION

[0028] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Example 1

[0030] A modified polyurethane prepolymer, which is a silane-terminated castor oil-modified polyurethane prepolymer, and a preparation method thereof comprises the following steps:

[0031] (1) In a closed reactor equipped with a stirrer, high-purity nitrogen protection, reflux condenser, and thermometer, 13.2 g of isophor diisocyanate and 8.0 g of polyether polyol were added and reacted at 85° C. for 3 h;

[0032] (2) cooling to 58° C., adding 18.6 g of castor oil, and then heating to 83° C. to react for 2 h to obtain an isocyanate-terminated castor oil-modified polyurethane prepolymer;

[0033] (3) 9.5 g of 3-aminopropyltriethoxysilane was added and reacted at 65° C. for 4 h until no isocyanate groups were detected in the system to obtain the modified polyurethane prepolymer.

[0034] Example 2

[0035] A modified aluminum hydroxide, wherein aluminum phosphate is in-situ grown on the surface of aluminum hydroxide and then a triazine derivative is grafted thereon, and the preparation method thereof comprises the following steps:

[0036] A. Add 5.6 g of aluminum hydroxide powder to 50 ml of anhydrous ethanol and stir to disperse, then add 10 ml of phosphoric acid to the suspension, stir to react for 5 hours, and after the reaction is completed, filter, wash, and dry the suspension to obtain aluminum hydroxide powder coated with aluminum phosphate;

[0037] B. Add 3.7 g of cyanuric chloride to 30 ml of tetrahydrofuran and 20 ml of triethylamine under a nitrogen atmosphere, stir to dissolve the cyanuric chloride, then uniformly dropwise add 11.7 g of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionohydrazide, react in an ice bath for 5 h after the dropwise addition is completed, then dropwise add 4.4 g of 3-aminopropyltriethoxysilane to the reaction system, raise the temperature to 60° C., and keep the temperature for 4 h. After the reaction is completed, cool and filter to remove triethylamine hydrochloride, remove tetrahydrofuran by vacuum distillation, then add ethyl acetate, dry and filter, and vacuum distill the filtrate to obtain a triazine nitrile derivative;

[0038] C. Add 11.2 g of aluminum hydroxide powder coated with aluminum phosphate into 80 ml of 95 vol% ethanol aqueous solution, and ultrasonically disperse for 12 min. Adjust the pH of the solution to 3-4 with hydrochloric acid aqueous solution, and then slowly add 4.6 g of triazine derivative into the above dispersion, and continue ultrasonically dispersing for 8 min. Heat to 80° C. and keep warm for 4 h. After cooling, filter, wash and dry to obtain the modified aluminum hydroxide.

[0039] Example 3

[0040] An ammonium polyphosphate microcapsule, wherein the ammonium polyphosphate microcapsule is prepared by modifying ammonium polyphosphate with melamine and then coating it with polypyrrole. The preparation method thereof comprises the following steps:

[0041] a. Dissolve 25 g of ammonium polyphosphate in 150 ml of 50 vol% ethanol aqueous solution, and disperse by ultrasonic at 50°C for 30 min. Then add 2.4 g of melamine to the solution and continue to disperse by ultrasonic for 10 min.

[0042] b. Raise the temperature to 120°C, stir and react for 1 hour, lower the temperature to 90°C, continue to react for 2 hours, drop 1.1 g of 3-glycidyloxypropyltriethoxysilane into the solution, react at 60°C for 1 hour to obtain modified ammonium polyphosphate;

[0043] c. Add 0.5 ml of pyrrole to the solution, disperse it ultrasonically at room temperature for 30 minutes, then slowly drop 30 ml of 10 wt% ferric chloride solution, stir and react for 10 hours, wash with water and ethanol for 3 to 5 times, filter and dry to obtain polypyrrole microcapsule modified ammonium polyphosphate.

[0044] Example 4

[0045] A functional pressure-sensitive adhesive based on polyurethane comprises the following raw materials in parts by weight: 72 parts of modified polyurethane prepolymer, 0.5 parts of stannous octoate, 25 parts of 1-4-butanediol, 12 parts of modified aluminum hydroxide, 4 parts of ammonium polyphosphate microcapsules, 0.03 parts of polyether modified silicone, and 0.1 parts of phosphate ester; the modified polyurethane prepolymer is prepared in Example 1, the modified aluminum hydroxide is prepared in Example 2, and the ammonium polyphosphate microcapsules are prepared in Example 3;

[0046] The production method of the functional pressure-sensitive adhesive based on polyurethane comprises the following steps: mixing a modified polyurethane prepolymer, stannous octoate and 1-4-butanediol, reacting at 58°C for 0.8h, then adding modified aluminum hydroxide, ammonium polyphosphate microcapsules, polyether modified silicone and phosphate ester and mixing evenly, and vacuum degassing for 30min to obtain a functional pressure-sensitive adhesive based on polyurethane.

[0047] Example 5

[0048] A functional pressure-sensitive adhesive based on polyurethane comprises the following raw materials in parts by weight: 60 parts of modified polyurethane prepolymer, 1 part of stannous octoate, 20 parts of 1-4-butanediol, 14 parts of modified aluminum hydroxide, 3 parts of ammonium polyphosphate microcapsules, 0.5 parts of mineral oil mixture, and 0.01 parts of fatty acid ester sulfate; the modified polyurethane prepolymer is prepared in Example 1, the modified aluminum hydroxide is prepared in Example 2, and the ammonium polyphosphate microcapsules are prepared in Example 3;

[0049] The production method of the functional pressure-sensitive adhesive based on polyurethane comprises the following steps: mixing a modified polyurethane prepolymer, stannous octoate and 1-4-butanediol, reacting at 55°C for 1 hour, then adding modified aluminum hydroxide, ammonium polyphosphate microcapsules, a mineral oil mixture and fatty acid ester sulfate, mixing evenly, and vacuum degassing for 20 minutes to obtain a functional pressure-sensitive adhesive based on polyurethane.

[0050] Example 6

[0051] A functional pressure-sensitive adhesive based on polyurethane comprises the following raw materials in parts by weight: 85 parts of modified polyurethane prepolymer, 0.1 parts of stannous octoate, 30 parts of 1-4-butanediol, 10 parts of modified aluminum hydroxide, 5 parts of ammonium polyphosphate microcapsules, 0.01 parts of modified polysiloxane emulsion, and 0.2 parts of alkyl sulfate; the modified polyurethane prepolymer is prepared in Example 1, the modified aluminum hydroxide is prepared in Example 2, and the ammonium polyphosphate microcapsules are prepared in Example 3;

[0052] The production method of the functional pressure-sensitive adhesive based on polyurethane comprises the following steps: mixing a modified polyurethane prepolymer, stannous octoate and 1-4-butanediol, reacting at 55°C for 0.5h, then adding modified aluminum hydroxide, ammonium polyphosphate microcapsules, modified polysiloxane emulsion and alkyl sulfate, mixing evenly, and vacuum degassing for 40min to obtain a functional pressure-sensitive adhesive based on polyurethane.

[0053] Comparative Example 1

[0054] A functional pressure-sensitive adhesive based on polyurethane comprises the following raw materials in parts by weight: 72 parts of modified polyurethane prepolymer, 0.5 parts of stannous octoate, 25 parts of 1-4-butanediol, 4 parts of ammonium polyphosphate microcapsules, 0.03 parts of polyether modified silicone, and 0.1 parts of phosphate ester; the modified polyurethane prepolymer is prepared in Example 1, and the ammonium polyphosphate microcapsules are prepared in Example 3;

[0055] The production method of the above-mentioned polyurethane-based functional pressure-sensitive adhesive is the same as that in Example 4.

[0056] Comparative Example 2

[0057] A functional pressure-sensitive adhesive based on polyurethane comprises the following raw materials in parts by weight: 72 parts of modified polyurethane prepolymer, 0.5 parts of stannous octoate, 25 parts of 1-4-butanediol, 12 parts of modified aluminum hydroxide, 0.03 parts of polyether modified silicone, and 0.1 parts of phosphate ester; the modified polyurethane prepolymer is prepared in Example 1, and the modified aluminum hydroxide is prepared in Example 2;

[0058] The production method of the above-mentioned polyurethane-based functional pressure-sensitive adhesive is the same as that in Example 4.

[0059] Performance Testing

[0060] The functional pressure-sensitive adhesive based on polyurethane prepared in Examples 4 to 6 and Comparative Examples 1 to 2 was uniformly coated on the surface of the PET film using a wire rod coater, and the thickness of the pressure-sensitive adhesive was 50 um. After coating, it was baked at 100 to 120° C. for 5 to 10 minutes, and then placed in a closed and clean space for aging for 24 hours. The PET film containing the pressure-sensitive adhesive film was taken out and cut into strips according to the test requirements, and then the following tests were performed:

[0061] 1. Flame retardant performance test

[0062] The vertical burning (UL94) test level is used to evaluate the ability of pressure-sensitive adhesive samples to extinguish after ignition. It is carried out according to the ASTM3801 standard, and the samples are tested in the size of 125mm×12.7mm×3.2mm. Pressure-sensitive adhesives are divided into no grade (NR), V-2, V-1 and V-0 grades according to the phenomenon such as how fast the sample extinguishes after ignition, whether molten droplets are produced during the combustion process, and whether the molten droplets can ignite the absorbent cotton. The limiting oxygen index (LOI) analysis is used to evaluate the ease of combustion of combustibles after ignition in the air. It is carried out according to the ASTMD2863 standard, and the samples are tested in the size of 80mm×10mm×4mm. During the combustion process, different combustibles consume different amounts of oxygen. The oxygen index meter calculates the oxygen index value of the combustible through the minimum oxygen consumption of the material combustion. The data obtained are shown in Table 1 below.

[0063] Table 1 Flame retardant test results of functional pressure-sensitive adhesive based on polyurethane

[0064]

[0065] As can be seen from Table 1, the pressure-sensitive adhesive for self-adhesive paper prepared in Examples 4 to 6 of the present invention all have strong flame retardant properties. This is due to the synergistic flame retardant effect of the modified aluminum hydroxide and ammonium polyphosphate microcapsules used in the present invention, which can greatly improve the flame retardant properties of the pressure-sensitive adhesive, and also reduce the total amount of flame retardants, reducing the impact on the adhesive properties of the pressure-sensitive adhesive. Among them, the modified aluminum hydroxide is a triazine derivative grafted after aluminum phosphate is in situ grown on the surface of aluminum hydroxide, which improves the dispersion effect of aluminum hydroxide in the polymer matrix. Aluminum phosphate has excellent chemical stability and heat oxidation resistance. At the same time, the P element in aluminum phosphate and the triazine derivative contain rich N and Si elements, which have an inhibitory effect on the combustion of polymer materials, thereby further improving the flame retardant effect of aluminum hydroxide. The ammonium polyphosphate microcapsules are modified by melamine and then coated with polypyrrole, which improves the compatibility of ammonium polyphosphate with the polymer matrix. The hydrophobicity of the coated ammonium polyphosphate is significantly improved, and it has better thermal stability and carbonization performance. In Comparative Examples 1 and 2, when modified aluminum hydroxide and ammonium polyphosphate microcapsules were added separately, the flame retardant properties of the pressure-sensitive adhesive were significantly reduced. This is because aluminum hydroxide and ammonium polyphosphate have a synergistic flame retardant effect.

[0066] 2. Aging resistance test

[0067] The pressure-sensitive adhesive samples were placed in a constant temperature test box at 120°C for 24h, 48h, and 72h for artificial aging test, and then the 180° peel strength of the pressure-sensitive adhesive was tested at each time period according to GB / T 2792-1998. The data obtained are shown in Table 2 below.

[0068] Table 2 Aging resistance test results of functional pressure-sensitive adhesive based on polyurethane

[0069]

[0070] It can be seen from the data in Table 2 that the functional pressure-sensitive adhesive based on polyurethane prepared in Examples 4 to 6 of the present invention and Comparative Example 2 has a relatively long-lasting aging resistance, while the functional pressure-sensitive adhesive based on polyurethane prepared in Comparative Example 1 has poor aging resistance because modified aluminum hydroxide is added. The modified aluminum hydroxide of the present invention is a triazine derivative grafted after aluminum phosphate is in situ grown on the surface of aluminum hydroxide. The triazine derivative has a hindered phenol unit, which can also give the pressure-sensitive adhesive good aging resistance.

[0071] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0072] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A functional pressure-sensitive adhesive based on polyurethane, characterized in that: The invention comprises the following raw materials in parts by weight: 60 to 85 parts of modified polyurethane prepolymer, 0.1 to 1 part of stannous octoate, 20 to 30 parts of 1-4-butanediol, 10 to 14 parts of modified aluminum hydroxide, 3 to 5 parts of ammonium polyphosphate microcapsules, 0.01 to 0.5 parts of defoaming agent, and 0.01 to 0.2 parts of wetting agent; The modified polyurethane prepolymer is a silane-terminated castor oil-modified polyurethane prepolymer, the modified aluminum hydroxide is obtained by in-situ growing aluminum phosphate on the surface of aluminum hydroxide and then grafting a triazine derivative, and the ammonium polyphosphate microcapsule is obtained by modifying ammonium polyphosphate with melamine and then coating it with polypyrrole.

2. The polyurethane-based functional pressure-sensitive adhesive according to claim 1, characterized in that: The defoaming agent is one or more of polyether modified silicone, mineral oil mixture, and modified polysiloxane emulsion.

3. The functional pressure-sensitive adhesive based on polyurethane according to claim 1, characterized in that: The wetting agent is one or more of alkyl sulfates, sulfonates, fatty acids, fatty acid ester sulfates, carboxylic acid soaps, and phosphates.

4. The polyurethane-based functional pressure-sensitive adhesive according to claim 1, characterized in that: The preparation method of the modified polyurethane prepolymer comprises the following steps: (1) In a closed reactor equipped with a stirrer, high-purity nitrogen protection, reflux condenser, and thermometer, first add isophor diisocyanate and polyether polyol, and react at 80-90° C. for 2-4 hours; (2) cooling the temperature to 55-60° C., adding castor oil, and then heating the temperature to 90-95° C. to react for 1-3 hours to obtain a polyurethane prepolymer modified with castor oil having terminal isocyanate groups; (3) adding 3-aminopropyltriethoxysilane and reacting at 60-70° C. for 3-5 hours until no isocyanate groups are detected in the system to obtain the modified polyurethane prepolymer.

5. The polyurethane-based functional pressure-sensitive adhesive according to claim 4, characterized in that: The molar ratio of isophor diisocyanate, polyether polyol and castor oil is 2-4:1:1, and the mass ratio of 3-aminopropyl triethoxysilane to isocyanate-terminated castor oil-modified polyurethane prepolymer is 3-4:

1.

6. The polyurethane-based functional pressure-sensitive adhesive according to claim 1, characterized in that: The preparation method of the modified aluminum hydroxide comprises the following steps: A. Add aluminum hydroxide powder into anhydrous ethanol and stir to disperse, then add phosphoric acid into the suspension, stir to react for 4 to 6 hours, filter, wash and dry the suspension after the reaction to obtain aluminum hydroxide powder coated with aluminum phosphate; B. Add cyanuric chloride to tetrahydrofuran and triethylamine under nitrogen atmosphere, stir to dissolve cyanuric chloride, then uniformly add 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionohydrazide, react in an ice bath for 4-6 hours after the addition is completed, then add 3-aminopropyltriethoxysilane dropwise to the reaction system, raise the temperature to 60°C, and keep the temperature for 3-5 hours. After the reaction is completed, cool and filter to remove triethylamine hydrochloride, remove tetrahydrofuran by vacuum distillation, then add ethyl acetate, dry and filter, and vacuum distill the filtrate to obtain a triazine nitrile derivative; C. Add aluminum hydroxide powder coated with aluminum phosphate to 95 vol% ethanol aqueous solution, ultrasonically disperse for 10 to 15 minutes, adjust the pH of the solution to 3 to 4 with hydrochloric acid aqueous solution, then slowly add the triazine derivative to the above dispersion, continue ultrasonic dispersion for 5 to 10 minutes, heat to 80°C and keep the reaction for 3 to 5 hours, filter after cooling, wash and dry to obtain the modified aluminum hydroxide.

7. The polyurethane-based functional pressure-sensitive adhesive according to claim 6, characterized in that: The molar ratio of cyanuric chloride, 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl hydrazide and 3-aminopropyltriethoxysilane is 1:2:1-2.

8. The polyurethane-based functional pressure-sensitive adhesive according to claim 1, characterized in that: The preparation method of the ammonium polyphosphate microcapsule comprises the following steps: a. Dissolve ammonium polyphosphate in 50 vol% ethanol aqueous solution, and disperse it ultrasonically at 50°C for 20 to 40 minutes. Then add melamine to the solution and continue to disperse it ultrasonically for 5 to 15 minutes. b. Raise the temperature to 120°C, stir and react for 1-2 hours, lower the temperature to 90°C, continue to react for 2-3 hours, drop 3-glycidyloxypropyltriethoxysilane into the solution, react at 60°C for 1-2 hours to obtain modified ammonium polyphosphate; c. Add pyrrole to the solution, disperse it ultrasonically at room temperature for 20 to 40 minutes, then slowly drop 8 to 10 wt% ferric chloride solution, stir and react for 8 to 12 hours, wash with water and ethanol for 3 to 5 times, filter and dry to obtain polypyrrole microcapsule modified ammonium polyphosphate.

9. The polyurethane-based functional pressure-sensitive adhesive according to claim 8, characterized in that: The mass ratio of the ammonium polyphosphate, melamine and pyrrole is 10:1:0.

5.

10. The method for producing a functional pressure-sensitive adhesive based on polyurethane according to any one of claims 1 to 9, characterized in that: The following steps are involved: The modified polyurethane prepolymer, stannous octoate and 1-4-butanediol are mixed, reacted at 55-60° C. for 0.5-1 h, and then modified aluminum hydroxide, ammonium polyphosphate microcapsules, defoaming agent and wetting agent are added and mixed evenly, and vacuum defoaming is performed for 20-40 min to obtain the polyurethane-based functional pressure-sensitive adhesive.

Images