Polyurethane microcapsule curing agent, adhesive, adhesive film and manufacturing process thereof

Abstract

A method for producing a polyurethane microcapsule curing agent, wherein the polyurethane microcapsule curing agent comprises a microcapsule structure comprising a wall material and a core material enclosed in the wall material, and wherein the manufacturing process comprises the following steps: mixing an oil-phase solution containing an isocyanate monomer and a catalyst with an aqueous-phase solution containing an emulsifier, and emulsifying the same to form an emulsion, wherein the aqueous-phase solution forms an aqueous phase and the oil-phase solution forms droplets; adding an amine solution to the emulsion and mixing the same such that the amine reacts with the isocyanate monomer at the interface;Heating the emulsion to which the amine solution has been added to 50-80°C and holding it at this temperature for 1-8 minutes, whereby the isocyanate monomer within the droplets reacts and is converted into an isocyanate dimer and / or an isocyanate trimer, and wherein the heating rate during heating is greater than or equal to 20°C / s; and cooling the system held at temperature to 20-30°C, wherein the cooling rate during cooling is greater than or equal to 20°C / s.

Description

TECHNICAL FIELD

[0001] The present invention relates to the technical field of polyurethane curing agents and polyurethane materials, in particular to a process for producing a polyurethane microcapsule curing agent, a polyurethane microcapsule curing agent produced by this process, and the application of the polyurethane microcapsule curing agent in polyurethane materials such as adhesives (glue), coatings, adhesive films, and the like. STATE OF THE ART

[0002] Curing agents, also known as hardeners, curing agents, or modifiers, are a class of substances or mixtures that enhance or control curing reactions. Curing agents are essential additives for the curing of resins and are required for adhesives, coatings, and potting compounds; otherwise, the resin will not cure.

[0003] To facilitate the use of coatings, adhesives, etc., many applications utilize one-component polyurethane material systems. The isocyanate is released upon heating, allowing the isocyanate to react with the active hydrogen-containing components to increase crosslinking density and thus achieve curing. The above-mentioned one-component polyurethane material systems contain a latent curing agent component that can only act as a curing agent under specific conditions. The latent curing agent must be de-sealed at a specific temperature before the crosslinking reaction takes place, while it does not react at room temperature.

[0004] Existing technology has already developed a method for deactivating the surface of a TDI (toluene diisocyanate) dimer, an MDI (diphenylmethane diisocyanate) dimer, an IPDI (isophorone diisocyanate) dimer, or an IPDI trimer to form a microcapsule structure. This structure is formed into a stable suspension by protecting the colloid. The suspension is then added to an emulsion to produce a one-component polyurethane material system that can be quickly unsealed. This method of using solid dimers and trimers as raw materials to form a microcapsule structure is commonly referred to as the solid interstitial capsule formation program.

[0005] There are two main methods for solid interstitial capsule formation: spray-drying granulation and mechanical grinding. Both of these methods have the following problems: the spray-drying granulation process uses pyridine as a solvent. Pyridine has a very strong odor, and the particle size of the particles in the resulting suspension is generally 15-60 μm. After a period of storage, particles with a larger particle size will irreversibly sink to the bottom, resulting in complete product failure. During the grinding process, the particles produced by mechanical grinding will release a certain amount of unreacted monomer due to the crushing of large particles. This monomer will be trapped in the crystallization process and is difficult to separate from the particles after it is released.It will produce a certain amount of ineffective solids with the amine and water of the co-milling process, which then impairs the overall performance, and the process produces a large number of bubbles, which impairs processing and lowers the pH of the polyurethane dispersions. The pH of the products drops rapidly for a certain period of time after production is completed, and some of the more pH-sensitive emulsions gel and analyze immediately upon use.

[0006] The microcapsule curing agent is combined with polyurethane dispersions (PUD) to form an adhesive. After film formation, PUD is activated at high temperatures and penetrates through the wall material into the microcapsule for crosslinking. However, the appearance of the TDI dimer particles prepared by the two above methods is irregular, as shown in Fig. 1 (TDI dimer particles produced by spray-drying granulation) and Fig.As shown in Figure 2 (TDI dimer particles prepared by mechanical milling), the microcapsules formed by reaction with the deactivated amine in water are still irregular, and the thickness of the microcapsule wall material is also inconsistent. The microcapsules prepared using the two above-mentioned solutions are highly influenced by the process batch, and the shape and thickness of the wall material affect the rate and amount of penetration, and thus the cross-linking process and the properties of the final material.

[0007] The content disclosed in the above background technology is only for understanding the inventive concept and technical scheme of the present invention and does not necessarily belong to the prior art of the present patent application, and in the absence of clear evidence that the above content was disclosed on the filing date of the present patent application, the above background technology should not be used to evaluate the novelty and creativity of the present application. CONTENT OF THE PRESENT INVENTION

[0008] To overcome the deficiencies of the prior art, a purpose of the present invention is to provide an improved process for preparing a polyurethane microcapsule curing agent.

[0009] At the same time, the present invention further provides a polyurethane microcapsule curing agent produced by the production method and an application thereof, wherein in the production process of the polyurethane microcapsule curing agent, the excessive reaction between the highly active isocyanate and water is avoided, which reduces the generation of carbon dioxide, facilitates continuous production, and avoids the rapid drop in pH, so that it has better compatibility with a large number of emulsions, and the microcapsule obtained by the interfacial reaction has a uniform and smooth particle surface and a uniform thickness of the wall material, as well as a more stable and controllable penetration rate and curing and crosslinking rate for polymerization in the heated state.

[0010] To achieve the above purpose, the present invention uses the following technical solution: A method for producing a polyurethane microcapsule curing agent, wherein the polyurethane microcapsule curing agent comprises a microcapsule structure comprising a wall material and a core material enclosed in the wall material, and wherein the manufacturing method comprises the following steps: Mixing an oil phase solution containing an isocyanate monomer and a catalyst with a water phase solution containing an emulsifier and emulsifying them to form an emulsion, wherein the water phase solution forms a water phase (continuous phase) and the oil phase solution forms droplets (dispersed phase); Adding an amine solution to the emulsion and mixing them so that the amine reacts with the isocyanate monomer at the interface to form a wall material of the microcapsule; Heating the emulsion to which the amine solution has been added to 50-80°C and keeping it warm at that temperature for 1-8 min, wherein the isocyanate monomer within the droplets reacts and is converted into an isocyanate dimer and / or an isocyanate trimer, and wherein the isocyanate dimer and / or the isocyanate trimer form the core material of the microcapsule, and wherein the heating rate during heating is greater than or equal to 20°C / s; and cooling the kept-warm system to 20-30°C, wherein the cooling rate during cooling is greater than or equal to 20°C / s.

[0011] In some embodiments, the entire system is heated to 50-80°C within 1-10 s by controlling the heating rate to avoid water ingress during a long heating process.

[0012] Preferably, the manufacturing process comprises the step of adding a thickener to the refrigerated system for thickening, wherein the viscosity of the thickened system is 1000-2000 cps at 25°C.

[0013] Preferably, the manufacturing process includes a step of allowing the thickened system to stand for ripening, wherein ripening involves keeping the thickened polyurethane microcapsule curing agent warm at 20-30°C for 12-36 hours. During the ripening process, the remaining isocyanate monomers in the core material are completely converted into dimers under the action of a catalyst to form a microcapsule with an isocyanate dimer inside and a wall material with a certain strength on the outer wall.

[0014] According to some preferred embodiments of the present invention, before mixing the oil phase solution with the water phase solution, the temperature of the oil phase solution is controlled at 20-22°C. The isocyanate monomer and catalyst are added to the premixing vessel and mixed uniformly at approximately 20-22°C. Too low a temperature may cause the isocyanate monomer to crystallize, which is not conducive to the formation of homogeneous droplets in the water phase, while too high a temperature may cause the isocyanate monomer to prematurely convert into a large number of dimer crystals, which is also not conducive to the formation of homogeneous droplets.

[0015] According to some preferred embodiments of the present invention, the temperature of the system is controlled at 0-5°C during emulsification and the addition of the amine solution for the reaction. The low temperature of 0-5°C can greatly reduce the reaction rate of the isocyanate monomer and water and reduce the formation of bubbles, making the emulsified particle size controllable and maintaining a smooth micelle interface. In some embodiments of the present invention, the water phase solution is formed by adding an emulsifier to ice water, and then controlling the temperature of the water phase solution at 0-5°C.

[0016] According to some preferred embodiments of the present invention, during emulsification, the mass ratio of the emulsifier in the water phase solution to the isocyanate monomer in the oil phase solution is 0.01%-5%, in some embodiments preferably 0.1%-2%.

[0017] According to some preferred embodiments of the present invention, the particle size of the microcapsules in the polyurethane microcapsule curing agent is 1-10 µm, preferably 5 µm, and the rotational speed of the equipment during emulsification is 1000-9000 rpm. The particle size is controlled by the amount of emulsifier and the rotational speed of the emulsifying equipment, i.e., the particle size can be regulated during the reaction process, whereas in the conventional method, the particle size cannot be regulated during the subsequent process because the isocyanate dimer is first prepared.

[0018] According to some preferred embodiments of the present invention, the isocyanate monomer is an isocyanate having at least two isocyanate groups-NCO, preferably toluene diisocyanate TDI, e.g. T80, T100, etc. Alternatively, diphenylmethane diisocyanate MDI can be used as core material for forming the microcapsules.

[0019] According to some preferred embodiments of the present invention, a tubular reactor is used to heat and cool the emulsion to achieve rapid heating and cooling, with the front section of the tubular reactor being used to heat the emulsion to a set temperature within 1-10 seconds, and the rear section of the tubular reactor being used to cool the emulsion to a set temperature within 1-10 seconds. Continuous production using a tubular reactor is free from batch-to-batch stability issues and enables rapid heating and cooling.

[0020] According to some preferred embodiments of the present invention, the catalyst is one or a combination of one or more of 4-dimethylaminopyridine, pyridine, tri-tert-butylphosphine, tributylphosphine, triethylenediamine, 2,4,6-tris(dimethylaminomethyl)phenol, bis(dimethylaminoethyl)ether, 1,8-diazabicyclo[5.4.0]undeca-7-N-methylmorpholine, pentamethyldipropylidenediamine, 1-methyl-4-(2-dimethylaminoethyl)piperazine, dimethylaminopyridine, 2,2'-dimorpholine diethyl ether, N,N-dimethylbenzylamine, N,N'-dimethylethanolamine, pentamethyldiethylidenetriamine. The molar ratio between the catalyst and the isocyanate monomer is 0.001-0.5%, too little catalyst is not enough to produce crystals in a short time through the tubular reactor to improve the structural strength of the microcapsule, and too much catalyst will result in premature crystals that cannot be emulsified.

[0021] According to some preferred embodiments of the present invention, the amine in the amine solution is one or a combination of one or more of ammonia water, urea, ethylenediamine, pentodiamine, hexamethylenediamine, hydrazine hydrate, guanidine, adipic acid dihydrazide, polyetheramine, isophoronediamine, 4,4'-diaminodicyclohexylmethane, and diethanolamine. The molar ratio of amine to isocyanate monomer in the amine solution is 6-12%. The concentration in the mass percent of the amine solution is 5-35%, preferably about 10-30%.

[0022] The amine solution is a capsule-forming component that transforms the micelles into particles, triggering interfacial reactions on the surface of the micelles to form a homogeneous wall material. At the same time, the temperature of the ice water inhibits the reaction between water and NCO, so that NCO reacts primarily with the amine. The amine and NCO undergo interfacial reactions to form a thin polyurea layer, the wall material, which prevents water from penetrating the core material.

[0023] According to some preferred embodiments of the present invention, the emulsifier in the water phase solution is a polyoxyethylene ether-based Span emulsifier and / or a polyoxyethylene ether-based Tween emulsifier.

[0024] According to some preferred embodiments of the present invention, an antifoam agent is added to the water phase solution during emulsification, wherein the antifoam agent is an organosilicon-based antifoam agent and / or a mineral oil-based antifoam agent.

[0025] According to some preferred embodiments of the present invention, the thickener is one or a combination of one or more of xanthan gum, guar gum, cellulose, polyurethane thickener, polyacrylic acid thickener, and polyvinylpyrrolidone. The dosage of the thickener is 0.01-1%, with the viscosity of the thickened system being 1000-2000 cps at 25°C.

[0026] According to some preferred embodiments of the present invention, the manufacturing process further comprises a step of adding a preservative to the system after thickening, wherein the preservative is an isothiazolinone fungicide such as Kathon.

[0027] In a preferred embodiment of the present invention, the emulsion system containing the particles is rapidly heated to 50-80°C in a few seconds by controlling the heating rate and the cooling rate, which takes about 2 minutes, wherein the wall material already has a certain strength due to the higher reaction rate of the aromatic monomers and the isocyanate monomers have been partially converted into dimer solids at this temperature, so that the entire microcapsule already has a certain strength, and then the microcapsule is quickly cooled to a safe temperature (room temperature), which takes about 30 seconds, which avoids the penetration of water in the process and does not affect the isocyanate monomer and dimer in the core material.

[0028] In existing application scenarios, such as pesticides and flavorings, the core material of microcapsules is liquid. In order for the microcapsule to achieve a certain strength, the suspension is usually stirred at 40-50°C for 1-8 hours to form a solid wall material to prevent adhesion. However, in the application scenarios of the present invention, the high temperature for such a long time will cause a large amount of water to penetrate and react with the isocyanate monomer and dimer. At the same time, a large amount of air bubbles will be generated, which lowers the pH of the system. Therefore, in the present invention, the temperature is raised to 50-80°C in a very short time, so that part of the wall material is quickly matured to achieve a certain strength, and the core material will be converted into a large amount of solid dimers.Now the microcapsule already has a certain strength and is then quickly cooled to 20-30°C within a few seconds, further ripening is carried out so that the core material is completely converted into the dimers, which not only avoids the penetration of water into the core material but also the adhesion between the microcapsules.

[0029] In some embodiments of the present invention, a tubular reactor can be used to perform the continuous treatment of the above-mentioned emulsion heating and cooling. The tubular reactor can be divided into two sections, with the first section being dedicated to rapid heating and the second section being dedicated to cooling. Furthermore, the heating, cooling, and heat-holding time can be controlled by the length and spacing of the tubular reactor. After cooling to room temperature, the material is discharged, and a thickener is added to the system for thickening and to prevent settling. The mixture is then allowed to stand for maturation.

[0030] In the manufacturing process of the microcapsule curing agent, all raw materials used by the present invention are liquid, in some embodiments of the present invention, the manufacturing process comprises in particular the following steps: 1) Adding TDI and catalyst to the premix tank at about 20-22°C and mixing evenly to form a solution containing isocyanate monomer and catalyst, i.e., an oil phase solution; 2) Adding the emulsifier in ice water to form a water phase solution, which is the continuous phase, and adding the oil phase solution dropwise into the water phase solution to emulsify at high speed into droplets with controllable particle size and smooth interface, which is the dispersed phase; 3) then adding the amine solution dropwise, which serves as the capsule forming component, stirring and mixing to a uniform state, so that the amine has an interfacial reaction with the isocyanate monomer on the surface of the droplets and forms a uniform wall material; 4) rapid heating of the emulsion system obtained in step 3) to 50-80°C in a few seconds through a tubular reactor, which takes about 2 min, so that the wall material is quickly matured and at the same time the internal isocyanate monomer is converted into isocyanate dimer, and then rapid cooling; 5) Finally, cooling to room temperature and discharging the material, thickening the system to prevent settling, and then carrying out maturation so that the remaining TDI inside is completely converted into dimers under the action of the catalyst to then obtain the microcapsule and the polyurethane microcapsule curing agent, the whole process is called the capsule formation program of the continuous liquid state process.

[0031] Another purpose of the present invention is to provide a polyurethane microcapsule curing agent produced by the above production method, wherein the polyurethane microcapsule curing agent comprises an emulsion and a microcapsule dispersed in the emulsion, and wherein the microcapsule comprises a core material having an isocyanate dimer inside and a wall material having a polyurea layer formed by the reaction of amine with the isocyanate on the outside; and wherein the mass fraction of the microcapsule in the polyurethane microcapsule curing agent is 35-45%. In some embodiments, the emulsion comprises an emulsifier, a thickener, a preservative, and water, etc.

[0032] More specifically, in some embodiments of the present invention, the polyurethane microcapsule curing agent comprises, by mass percentage, 35-45 parts microcapsules, 0.1-2 parts emulsifier, 0.1-0.5 parts thickener, 0.1-0.5 parts preservative, and 54-65 parts water. Preferably, the polyurethane microcapsule curing agent comprises 39.5 parts microcapsules, 0.1 part emulsifier, 0.3 part thickener, 0.1% preservative, and 60 parts water.

[0033] Another purpose of the present invention is to provide an application of the above microcapsule curing agent in the manufacture of polyurethane materials, e.g., in the preparation into polyurethane glue (adhesive) or coatings, adhesive films and other products.

[0034] The present invention provides a method for producing a polyurethane adhesive, comprising the following steps: 1) preparing a polyurethane microcapsule curing agent by the above preparation method; 2) adding a vinyl acetate-ethylene emulsion to the polyurethane dispersion and adjusting the pH to 6 to 8, adding polyurethane microcapsule curing agent, additive, and water, and stirring to obtain the polyurethane adhesive; wherein the amount of the microcapsule curing agent added in the polyurethane adhesive is 3-20%; and wherein the mass ratio of polyurethane dispersion to vinyl acetate-ethylene emulsion is preferably 6:4.

[0035] According to some preferred embodiments of the present invention, the polyurethane dispersion is prepared by the following process: heating and dehydrating polyether polyols and / or polyester polyols and extending the chains by adding a chain extender;

[0036] Adding diisocyanate and catalyst to carry out a reaction until a certain content of isocyanate groups is reached to obtain an isocyanate-capped prepolymer;

[0037] Adding a solvent to dilute and cool, then adding sodium ethylenediamineethanesulfonate to extend the chain again;

[0038] Add tris(hydroxymethyl)aminomethane for capping, then add water for dispersing, and remove the solvent to obtain the polyurethane dispersion. The solvent can preferably be acetone.

[0039] In some embodiments of the present invention, the process for preparing the polyurethane dispersion comprises in particular the following steps: 1) Two polyester polyols with different molecular weights are placed in a reactor, heated and dehydrated, then a chain extender 1,4-butanediol (BDO) is added for chain extension while the temperature is reduced to 60°C under stirring; 2) Adding diisocyanate and catalyst, stirring at 80°C-90°C until a certain content of isocyanate groups NCO is reached to obtain an isocyanate-capped prepolymer; the adjusted content of isocyanate groups is about 1.3%; 3) Add a solvent, e.g. acetone, dilute and cool to 50°C; 4) Adding an aqueous solution of sodium ethylenediamineethanesulfonate (AAS) and stirring vigorously for 30 min to perform hydrophilic chain extension; 5) Adding an aqueous solution of tris(hydroxymethyl)aminomethane (TRIS) to completely react the remaining isocyanate, and then distilling to remove acetone solvent to obtain an aqueous polyurethane dispersion.

[0040] Compared with the polyurethane dispersion prepared by the conventional method, the method for preparing the polyurethane dispersion of the present invention uses tris(hydroxymethyl)aminomethane for capping, so that there are three more hydroxyl groups at both ends of the molecular chain of the prepared PUD, which is conducive to the reaction with the curing agent.

[0041] According to some preferred embodiments of the present invention, the pH is adjusted with a multifunctional amine additive such as AMP95 from Dow.

[0042] According to some preferred embodiments of the invention, the additives comprise one or more of a wetting agent, an antifoam agent or a thickener.

[0043] According to some preferred embodiments of the present invention, the viscosity of the polyurethane adhesive at 25°C is 1500-3000 mPa.s; the solids content is 35-60%.

[0044] The present invention provides a polyurethane adhesive prepared by the above preparation method, comprising a polyurethane dispersion and a microcapsule curing agent; wherein the mass ratio of the polyurethane dispersion to the microcapsule curing agent is 100:5-20. In some embodiments, the polyurethane adhesive comprises 70-85% polyurethane dispersion, 7-12% microcapsule curing agent, and 10-18% additive and water.

[0045] The present invention provides a method for producing a polyurethane adhesive film, comprising the following steps: preparing a polyurethane adhesive using the above production method; applying the polyurethane adhesive to a release paper, and drying it to obtain the polyurethane adhesive film. The temperature during drying is lower than 60°C, preferably lower than 55°C, to avoid activation of the microcapsule curing agent and premature reaction.

[0046] The present invention provides a polyurethane adhesive film produced by the above production method.

[0047] With the implementation of the above technical solution, the present invention has the following advantages compared with the prior art: with the method for producing a curing agent for polyurethane microcapsules according to the present invention, a continuous uniform wall material is formed by the interfacial reaction after emulsification of the liquid raw materials; by rapid heating and rapid cooling, the wall material is quickly matured, which avoids water penetration without affecting the isocyanate monomer and dimer in the core material; thus, the effective content of isocyanate dimer inside the microcapsule is significantly increased, which improves the efficiency of the crosslinking reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly explain the technical solution in the embodiments of the present invention, the figures to be used in the explanation of the embodiments will be briefly introduced below. Obviously, the figures shown below show only some embodiments of the present invention. Those skilled in the art can derive other figures based on the figures without requiring creative work. Fig. Figure 1 shows a scanning electron micrograph of a TDI dimer (ADDOLINK TT) used in the manufacturing process of a commercially available microcapsule curing agent; Fig. Figure 2 shows a scanning electron micrograph of dimer particles produced by a mechanical milling process; Fig.3 shows a scanning electron micrograph of microcapsule particles in a polyurethane microcapsule curing agent prepared in Embodiment 1-1 of the present invention; Fig. 4 is a schematic diagram of a process for producing a polyurethane microcapsule curing agent in Embodiment 1 of the present invention; Fig. 5 shows a schematic diagram of the principle of the experimental methods in Experiment I and Experiment IV of the present invention; Fig. 6 is a graphical representation of the DSC test curve of the dry film obtained in Experiment II according to Embodiment 1 of the present invention; Fig. 7 is a graphical representation of the DSC test curve of the dry film obtained in Experiment II according to Embodiment 2 of the present invention; Fig.8 is a graphical representation of the DSC test curve of the dry film obtained in Experiment II according to Comparative Example 2 of the present invention; Fig. Fig. 9 shows a graph of an infrared test obtained in Experiment III of the present invention; Fig. 10 shows a schematic diagram of an experiment procedure in Experiment V of the present invention. List of reference symbols 1 MDF board 2 adhesive tape 3 PVC film 4 Weight 5 Substrat 6 ejection hole 7 Glued object DETAILED DESCRIPTION

[0049] In conjunction with figures in the embodiments of the present invention, the technical solution in the embodiments of the present invention will be explained clearly and completely below so that those skilled in the art can better understand the technical solution of the present invention. Obviously, the described embodiments do not represent all embodiments, but only a part of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments in the present invention without creative work should be considered to be covered by the scope of the present invention.

[0050] Table 1 shows the abbreviations of the reagents used in the working examples according to the Chinese composition or function and the abbreviation of the manufacturer: Table 1 Description of some reagents Nr. abbreviation Composition or function Manufacturer's abbreviation 1 TDI Toluene diisocyanate Covestro 2 IPDI Isophorone diisocyanate Covestro 3 HDI Hexamethylene diisocyanate Covestro 4 BL 2514 Latent curing agent (TDI dimer) Covestro 5 AAS Sodium ethylenediamine ethyl sulfonate Evonik 6 TBUP Tributyl phosphate Sigma 7 TRIS Tris(hydroxymethyl)aminomethane Sigma 8 BDO 1,4-Butanediol Zhongtai 9 T403 Polyoxypropylenetriamine Huntsma 10 ALA Thickener OMG 11 L75N Thickener OMG 12 MB20 Organic bismuth catalyst Air Products 13 DS2130 Dispersants Osic 14 UL5120 Organosilicon wetting agents Osic 15 F908 Organosilicon antifoam agent Osic 16 F8916 Organosilicone antifoam agent Osic 17 Polyester polyol I 2000 molecular weight Osic 18 Polyester polyol II 1800 molecular weight Osic 19 NE580NE580 NCO=20.5% aqueous HDI curing agent Osic 20 Span 60 Emulsifier Sea Petrochemicals 21 VAE706 Vinyl acetate-ethylene emulsion Brave 22 AMP95 Multifunctional amine additive Dow Example 1 Preparation of the microcapsule curing agent

[0051] The conventional method for preparing a polyurethane microcapsule curing agent is to prepare TDI into a solid dimer, which is then dispersed in water for activation. Fig. 1 shows the appearance of commercially available dimer particles and Fig.2 shows the appearance of dimers produced by milling. It can be seen that the surface of such solids varies in size and is extremely unsmooth, and the shape of the shell of the product produced by deactivation is uncontrollable, which manifests itself in the fact that the penetration of water into the microcapsule and the penetration of the heated polymer, such as the polyurethane dispersion, into the microcapsule are also uncontrollable in practical use. In the present invention, the liquid continuous process is used to produce a polyurethane microcapsule curing agent, and the resulting microcapsules are controllable in terms of particle size and the surface is relatively smooth, as shown in Fig. 3, and they are controllable with respect to the rate of water penetration into the wall material and the penetration of the heated polymer in the application process.

[0052] The interfacial polymerization method involves emulsifying or dispersing a core material in a continuous phase in which a wall material is dissolved, and then forming a microcapsule on the surface of the core material through a monomer polymerization reaction. Using the interfacial polymerization method, a microcapsule with a smooth and continuous surface can be produced, thus solving the problem of irregular particles.Although such capsule formation programs exist in the pharmaceutical, flavor, and other industries, the difference is that when using the interfacial polymerization method, the existing technology does not need to consider the residual isocyanate during the capsule formation and maturation process. Therefore, heating is carried out for a longer period of time (essentially longer than 1 hour) so that the wall material reaches a certain strength as quickly as possible to prevent adhesion between the microcapsules. However, a large amount of isocyanate (isocyanate group-NCO) in the polyurethane microcapsule curing agent must be retained for the subsequent crosslinking reaction. If the temperature exceeds 40°C for a long time, a large amount of water will penetrate through the wall material into the microcapsule, resulting in a significant reduction in the internal active ingredient.Therefore, there is a contradiction between preventing adhesion by heating and ripening the microcapsules and maintaining a large amount of isocyanate (dimer) by preserving at low temperatures, which cannot be resolved by the existing implementation of the interfacial polymerization method.

[0053] In order to solve the above problem and achieve the above purpose, a method for producing the polyurethane microcapsule curing agent according to the present invention uses the following steps: 1) Adding TDI and catalyst to the premix tank at about 20-22°C and mixing evenly to form a solution containing isocyanate monomer and catalyst, i.e., an oil phase solution; 2) Adding the emulsifier into ice water to form a water phase solution (the temperature is controlled at 0-5°C), and adding the oil phase solution dropwise into the water phase solution to emulsify at high speed into droplets with controllable particle size and smooth interface; 3) then adding the amine solution dropwise, which serves as the capsule forming component, stirring and mixing so that the amine has an interfacial reaction with the isocyanate monomer on the surface of the droplets and forms a uniform wall material; 4) rapid heating of the emulsion to 50-80°C in a few seconds through a tubular reactor, which takes about 2 min, so that the wall material is quickly matured and at the same time the internal isocyanate monomer is converted into isocyanate dimer, and then rapid cooling; 5) finally cooling to room temperature and discharging the material, thickening the system to prevent settling, and then carrying out maturation so that the remaining TDI inside is completely converted into dimers under the action of the catalyst to then obtain the microcapsule and the polyurethane microcapsule curing agent. Example 1-1

[0054] As in Fig. 4, a method for producing the polyurethane microcapsule curing agent in the present embodiment uses the following steps: 1) Preparation of the oil phase solution Adding 500kg of TDI and 0.25kg of tributylphosphine to the premix tank at 20°C and mixing uniformly to form a solution containing isocyanate monomer and catalyst, i.e., an oil phase solution; 2) Preparation of the water phase solution Adding 5 kg of emulsifier and 0.5 kg E antifoam in 500 L of ice water and mixing evenly to obtain an aqueous solution containing the emulsifier, i.e. a water phase solution, controlling the temperature at 1°C; 3) Emulsification The oil phase solution obtained in step 1) is introduced into the emulsifying device (continuous high-speed emulsifier) ​​at a flow rate of 27.5 kg / h and the water phase solution obtained in step 2) at a flow rate of 30 kg / h for high-speed emulsification, so that the oil phase solution forms an emulsion with a controllable particle size and a solid content of 47.8%. The particle size of the droplets is controlled by the amount of emulsifier added and the machine speed. The system temperature during the emulsification process is controlled at 1°C. 4) Preparation of the amine solution Add 1.64 kg of polyetheramine to 17.5 kg of deionized water and stir until a homogeneous amine solution with a concentration of 9.4%, i.e. the capsule forming component, is obtained. 5) Interfacial reaction The emulsion emulsified in step 3) is introduced at a flow rate of 57.5 kg / h and the amine solution obtained in step 4) at a flow rate of 17.5 kg / h into a continuous mixer, allowing the interfacial reaction between the diluted amine solution and the isocyanate to occur at the droplet surface to form a polyurea layer, i.e., the wall material. The system temperature during the interfacial reaction process is controlled at 1°C. 6) Maturation of the wall material Rapid heating of the emulsion system in a tubular reactor at a heating rate of 20°C / s to 80°C in 4 s, which takes 2 min, so that the wall material is rapidly matured and the TDI monomer in the core material is rapidly converted into a dimer under the action of the catalyst and the temperature, followed by cooling at a cooling rate of 30°C / s in 2 s, which takes 30 s; 7) Anti-settlement, anti-corrosion Cooling to 20°C and discharging the material at room temperature, adding 0.3% by mass of xanthan gum thickener to the system for thickening and anti-settlement; adding 0.1% by mass of isothiazolinone fungicide, such as Kathon, to the system; 8) Maturation of the core material Allowing the system to stand at room temperature for maturation, keeping at 25°C for 24 h, so that the non-dimerized TDI in the core material is completely converted into a dimer under the action of the catalyst to obtain a microcapsule and a polyurethane microcapsule curing agent, wherein the solid content is 39.2% and the viscosity is 1580 cps. Example 1-2

[0055] The embodiment is carried out with reference to the embodiment 1-1, and the difference from the embodiment 1-1 is that in step 3) in the present embodiment, 3.28 kg of amine is added to 17.5 kg of deionized water, with the other steps and parameters remaining unchanged. Example 1-3

[0056] The embodiment is carried out with reference to the embodiment 1-1, and the difference from the embodiment 1-1 is that in step 1) in the present embodiment, 2.2 kg of catalyst 4-dimethylaminopyridine is added to 500 kg of TDI, with the other parameters remaining unchanged. Comparison example 1-1

[0057] The difference of Comparative Example 1-1 from Working Example 1-1 is that in the interfacial reaction (capsule formation), the amine with a concentration of 100% is directly used instead of a diluted amine solution, which results in a large number of lumps and precipitates during the reaction, and a stable microcapsule dispersion cannot be formed. Comparison example 1-2

[0058] The difference between the comparative example and Working Example 1-1 is that the maturation of the wall material involves stirring at 50°C for 6 hours. The other steps and parameters are essentially the same as those in Working Example 1-1. During the maturation process of the wall material, a large amount of air bubbles and a small amount of lumps and precipitates are formed. After filtration of the precipitates, a dispersion with a viscosity of 4530 cps and a solid content of 35.8% is obtained. Comparison example 1-3

[0059] The difference between Comparative Example and Working Example 1-1 is that no thickener is added to the system for anti-settling treatment. The other steps and parameters are essentially the same as those in Working Example 1-1. A dispersion with a viscosity of 320 cps and a solid content of 39.4% is obtained. The system precipitates strongly after two days and can be returned to its original state after stirring. However, it soon settles and forms hard lumps after one week, which cannot be returned to their original state after stirring. Example 2-1 Production of a thermosetting one-component polyurethane adhesive

[0060] The method for producing a thermosetting one-component polyurethane adhesive in the present embodiment comprises the following steps: 1) Preparation of the microcapsule curing agent

[0061] Add 500 g of TDI monomer and 0.05 g of tributylphosphine to a container, maintain the temperature at 20-25°C, and stir until uniform to form an oil phase solution; add 8 g of Span 60 to 828 g of ice water and stir until uniform to form a water phase solution; slowly drop the above oil phase solution into the water phase solution, and simultaneously conduct high-speed dispersion for half an hour to form a stable emulsion.

[0062] Slowly dropping 100g of 30% concentration polyetheramine aqueous solution, stirring simultaneously for half an hour, introducing into the tubular reactor, rapid heating to 80°C in 3 s, keeping warm for 2 min, then rapid cooling to 25°C in 2 s, keeping warm for 30 s and discharging the material into the mixing tank, adding 20g of DS2130 dispersant, 2g of F908 antifoam agent and 2g of ALA thickener with stirring to prepare a microcapsule curing agent A after maturation for 36 h, which has a viscosity of 1540 mPa s at 25°C, a solid content of 39% and a microcapsule particle size D50 of about 5 µm. 2) Preparation of the water-based polyurethane dispersion

[0063] Add 500 g of polyester polyol I and 50 g of polyester polyol II to the reactor, heat to 115°C, and dehydrate for 1 h. Then add 2.5 g of BDO and cool to 60°C with stirring. Then add 42 g of HDI, 28 g of IPDI, and 3 g of MB20. Keep heated at 80°C-90°C and stir until the isocyanate content reaches 1.28%. Add 850 g of acetone and lower the system temperature to 50°C.

[0064] Dilute 7.0 g of AAS in 55 g of water and then add it to the system and stir for 30 min; then dissolve 8 g of TRIS in 555 g of aqueous solution and add it to the system for dispersion, and finally distill to remove acetone to obtain a water-based polyurethane dispersion B. The obtained polyurethane dispersion solid has a melting point of 44.12°C, a solid content of 49.2 wt%, and a viscosity of 1290 mPa.s at 25°C. 3) Production of the polyurethane adhesive

[0065] Add 300 g of water-based polyurethane dispersion B and 200 g of VAE706 to a container, use AMP95 to adjust the pH to about 7, then add 35 g of microcapsule curing agent A, 0.5 g of wetting agent UL5120, 0.5 g of antifoam F8916 and 50 g of water, stir for half an hour and add 0.5 g of thickener L75N to prepare the finished product polyurethane adhesive, which has a viscosity of 2130 mPa s at 25°C and a solid content of 45%. Example 2-2

[0066] Based on the embodiment 2-1, the amount of the microcapsule curing agent A is increased from 35 g to 50 g, and everything else remains unchanged. Example 2-3

[0067] Based on the embodiment 2-1, the amount of the microcapsule curing agent A is increased from 35 g to 100 g, and everything else remains unchanged. Comparison example 2-1

[0068] Based on the working example 2-1, 35g of microcapsule curing agent A is replaced by Covestro Dispercoll XP BL 2514, and everything else remains unchanged. Comparison example 2-2

[0069] Based on the working example 2-1, 35 g of microcapsule curing agent A is replaced by 50 g of Covestro Dispercoll XP BL 2514, and everything else remains unchanged. Comparison example 2-3

[0070] Based on the working example 2-1, 35g of microcapsule curing agent A is replaced by 100g of Covestro Dispercoll XP BL 2514, and everything else remains unchanged. Comparison example 2-4

[0071] Based on the embodiment 2-1, the addition amount of Span 60 is increased to 18 g, and the other conditions remain unchanged, thereby a microcapsule curing agent B can be obtained which has a solid content of 39%, a viscosity of 4130 mPa·s and a particle size of D50<1µm. Comparison example 2-5

[0072] Based on the working example 2-1, 35 g of microcapsule curing agent A is replaced by 35 g of microcapsule curing agent B, and everything else remains unchanged. Comparison example 2-6

[0073] Based on the working example 2-1, 35 g of microcapsule curing agent A is replaced by 50 g of microcapsule curing agent B, and everything else remains unchanged. Comparison example 2-7

[0074] Based on the working example 2-1, 35 g of microcapsule curing agent A is replaced by 100 g of microcapsule curing agent B, and everything else remains unchanged. Comparison example 2-8

[0075] Based on Working Example 2-1, 35 g of microcapsule curing agent A is replaced by 35 g of NE580 curing agent, and everything else remains unchanged. Comparison example 2-9

[0076] Based on Embodiment 2-1, no microcapsule curing agent A or no microcapsule curing agent B is added, and everything else remains unchanged. Example 3 and Comparative Example 3 Polyurethane adhesive film

[0077] The adhesive prepared in Embodiment 2 and Comparative Example 2 is applied to the release paper (film) by roll coating or slot coating, etc., and dried in a variable-temperature oven to form Embodiment 3 and Comparative Example 3. The drying temperature is below 55°C to prevent activation of the microcapsule curing agent. Tests and results1) Scanning electron microscopy (SEM)

[0078] Scanning electron microscopy (SEM) tests are carried out on the raw material of the commercially available microcapsule curing agent (TDI dimer, ADDOLINK TT), the dimer particles obtained by the milling program and the microcapsule curing agent prepared in the working example 1-1, and the obtained scanning images are as shown in Fig. 1, Fig. 2 and Fig. 3 shown.

[0079] Out of Fig. 1 and Fig.2, it is evident that the TDI dimer solids are of different sizes and have a very non-smooth surface, and the shape of the shell of the product produced by deactivation is uncontrollable, which means that the penetration of water into the microcapsule and the penetration of late PUD are also uncontrollable. In the microcapsules according to Fig. 3, the particle size is relatively controllable and the surface is smooth, and the rate of water penetration into the wall material and the penetration of the polymer in the application process are controllable. Fig. 3 shows the microcapsules produced by Embodiment 1-1, wherein the diameter of the microcapsules is 5 µm. 2) related experimentsExperiment 1

[0080] The microcapsule curing agents prepared in Working Examples 1-1, 1-2, 1-3, and Comparative Example 1-2 were processed into adhesives according to the same formula, and then scraped onto the MDF board 1 using a 50 µm preparator with a glue area of ​​50 x 200 mm, and then dried to obtain the adhesive film 2, which was then laminated with a PVC film 3 (450 µm) and then subjected to a 180° peel test. After hot pressing at 100°C for 2 minutes, a weight 4 of 10 N was immediately hung and placed in the oven to observe the peeling distance (within 5 minutes) of the weight at various temperatures (70-90°C), as shown in Fig. 5, where 70°C, 80°C, and 90°C are independent experiments. The test results (unit: cm) are shown in Table 2: Table 2 Test result Implementation example 1-1 Implementation example 1-2 Implementation examples 1-3 Comparison example 1-2 70 °C <1 <1 <1 12 80 °C 2 5 5 20 90 °C 3 7 8 20

[0081] As can be seen from the experimental results in Table 2, Working Examples 1-1, 1-2, and 1-3 exhibit high initial heat resistance at 70°C after hot pressing at 100°C for 2 minutes, indicating that PUD and isocyanate have reacted to a certain extent to increase the molecular weight, and the reaction efficiency is high. The degree of crosslinking of Working Examples 1-2 is lower than that of Working Examples 1-2, which means that the polyurethane microcapsule curing agents prepared in Working Example 1 can be unsealed and crosslinked in the traditional sense at a lower temperature and in a shorter time, while conventional curing agents may need to react at 120°C for 1 hour. Furthermore, the peeling effect of Working Examples 1-1 and 1-2 at 80°C and 90°C is much better than that of Comparative Example. Experiment 2

[0082] The polyurethane microcapsule curing agents prepared in Working Example 1-1, Working Example 1-2 and Comparative Example 1-2 are processed into adhesive according to the same formula and are each applied to the release paper to prepare a dry film having a thickness of 50 µm, and the samples of the dry film are tested by DSC, and the obtained graphs are shown in Fig. 6-8.

[0083] It is over Fig.6-8 that the enthalpies of the DSC test curves corresponding to the dry films of Embodiment 1-1, Embodiment 1-2, and Comparative Example 1-2 are 22.616 J, 23.723 J, and 12.093 J, respectively, that is, the enthalpies of the DSC test curves of Comparative Example 1-2 are much smaller than those of Embodiment 1-1 and Embodiment 1-2, indicating that the reaction efficiency of the polyurethane microcapsule curing agent and PUD prepared in the embodiment is greater than that of Comparative Example 1-2. Experiment 3

[0084] The three dry films produced in Experiment 2 are subjected to infrared testing and the results are shown in Fig. 9 shown.

[0085] The infrared spectrum in Fig. 9 shows that in the range of 2240-2280 cm -1the peaks of Working Examples 1-1 and 1-2 are much larger than those of Comparative Example 1-2. The range of 2240-2280 cm- 1 corresponds to the peak of the stretching vibration of -N=C=O, indicating that the curing agents prepared in Working Examples 1-1 and 1-2 contain more active isocyanate components. The PUD polymer activated at a temperature of 70-100°C penetrates the microcapsule wall, penetrates the microcapsule, and reacts with these encapsulated isocyanates. The more active isocyanates contained in Curing Agent 1, the more efficient the reaction. Experiment 4

[0086] As in Fig. As shown in Figure 5, some of the polyurethane adhesives from Working Example 2 (2-1 to 2-3) and Comparative Example 2 (2-1 to 2-9) are subjected to an initial heat resistance test: The polyurethane adhesive is applied to the MDF board 1 with a preparator to form an adhesive layer with a wet film thickness of 50 µm (width 5 cm, length 20 cm). It is then dried in an oven at room temperature or below 40°C until it no longer adheres, forming the adhesive film 2. A 350 µm thick PVC film 3 is then placed over the top of the adhesive film 2 for a 180° peel test. A hot press is used to press the film at 60°C for 2 minutes or at 80°C for 2 minutes. The workpiece is then immediately placed in an oven at 80°C with a 1 kg weight 4, and the displacement of the PVC film is observed (within 5 minutes). The displacement results of the initial heat resistance test (cm) are shown below: Table 3 Test results Example 2-2 Comparison example 2-1 2-2 2-3 2-5 2-6 2-7 2-8 2-9 Hot pressing at 60°C 2,78 4,48 3,52 6,23 5,33 6,87 9,23 20,0 20,0 Hot pressing at 80°C 0,55 2,38 1,03 1,85 2,26 2,84 5,19 20,0 20,0

[0087] It can be seen from the experiments and the results in Table 3 that the effect of the embodiment is significantly better than that of the comparative example. The microcapsule curing agent with a particle size of approximately 1-5 µm is more suitable. Although the microcapsules in Comparative Examples 2-5 to 2-7 have a smaller particle size (D50<1 µm) and a larger specific surface area, the actual crosslinking effect is not good because the wall material contains too much isocyanate, the ineffective solid content is too high, and the effective isocyanate content is too low. Comparative Example 2-9 without a curing agent results in complete peeling under the initial heat resistance test conditions, while Comparative Example 2-8 using a two-component curing agent (NE580) does not improve the initial heat resistance because crosslinking does not occur within a short time. Experiment 5

[0088] As in Fig. As shown in Figure 10, the polyurethane adhesive films prepared in Working Example 3 and Comparative Example 3 were subjected to an ejection test: the adhesive film 2 was sandwiched between the substrate 5 (size 4 x 4 cm) and the bonded material 7 (diameter 2.1 cm), hot-pressed at 80°C for 120-240 s, and moved to the ejection hole 6 (diameter 0.9 cm) with a rod-shaped object at a speed of V = 10 mm / min, and then ejected. The maximum pressure exerted on the bonded object when it falls was converted into the pressure strength (MPa), i.e., the ejection value. The test substrate 5 was 304 stainless steel treated with a primer (e.g., silane, primer, UPUV, etc.), and the bonded object was PC, PET, PI, or fabric. The ejection test results (MPa) are shown below: Table 4 Test results Example 3-2 Comparison example 3-1 3-2 3-3 3-5 3-6 3-7 Output value (MPa) 11,82 7,32 10,55 7,19 5,94 7,89 6,55

[0089] From the experiments and the data in Table 4, it can be seen that the effect of the embodiment is significantly better than that of the comparative example. According to the results of Experiment 4, the microcapsule curing agent with a particle size of approximately 1-5 µm is more suitable. It has a smaller particle size (D50<1 µm) and a larger specific surface area. However, the wall material absorbs too much isocyanate, and the ineffective solid content is too high, resulting in poor crosslinking effect in practice and poor ejection test results.

[0090] Since the crosslinking efficiency and the specific surface area of ​​the latent curing agent are proportional within a certain range, and the emulsion particles (15-60 μm) of the existing technology are relatively large, it leads to a relatively large amount of added latent curing agent, and the excessive amount of latent curing agent is equivalent to a solid filler, which affects the final performance of the adhesive film.With the method for producing the polyurethane microcapsule curing agent of the present invention, the particle size of the microcapsule is controllable (1-5 μm), which prevents the emulsion from settling too quickly, and even if some of it settles after a long storage period, it can be restored to normal by simple stirring; the wall material formed by interfacial reaction after emulsification of the liquid raw material is continuous and uniform, which makes the penetration ability of PUD to the latent curing agent stable after activation, and the problem of releasing a large amount of carbon dioxide in the later stage does not exist; and there is no problem of batch stability in the continuous production method.On the other hand, the molecular weight of existing PUDs is large and the number of terminal hydroxyl groups or amine groups is small, so the number of those that can react with the latent curing agent is small; in the preparation of the polyurethane dispersion of the present invention, the introduction of TRIS increases the hydroxyl group content without decreasing the molecular weight, which promotes the reaction with the microcapsule curing agent and improves the crosslinking density and efficiency.

[0091] The above embodiments serve only to explain the technical concepts and features of the present invention. The goal is to enable those skilled in the art to understand and practice the contents of the present invention; the scope of the present invention is not limited to this. Any changes or modifications made based on the essence of the present invention should be considered to be within the scope of the present invention.

Claims

[1] A process for producing a polyurethane microcapsule curing agent, wherein the polyurethane microcapsule curing agent comprises a microcapsule structure, characterized by that the microcapsule structure comprises a wall material and a core material enclosed in the wall material, wherein the manufacturing method comprises the following steps: Mixing an oil phase solution containing an isocyanate monomer and a catalyst with a water phase solution containing an emulsifier and emulsifying them to form an emulsion, wherein the oil phase solution forms droplets dispersed in the water phase solution; Adding an amine solution to the emulsion and mixing them so that the amine reacts with the isocyanate monomer at the droplet interface to form a wall material of the microcapsule; Heating the emulsion to which the amine solution has been added within 1-10 s to 50-80°C and keeping it warm at that temperature for 1-8 min, whereby the isocyanate monomer within the droplets reacts and is converted into an isocyanate dimer and / or an isocyanate trimer, and wherein the isocyanate dimer and / or the isocyanate trimer forms the core material of the microcapsule; and Cooling of the warmed system to 20-30°C within 1-10 s and discharging. [2] Manufacturing process according to claim 1, characterized by that the heating rate during heating is greater than or equal to 20°C / s and the cooling rate during cooling is greater than or equal to 20°C / s. [3] Manufacturing process according to claim 1, characterized bythat the manufacturing process comprises a step of adding a thickener to the refrigerated system for thickening, wherein the viscosity of the thickened system is 1000-2000 cps at 25°C; and / or the process comprises a step of keeping the refrigerated system warm at 20-30°C for 12-36 h. [4] Manufacturing process according to claim 1 or 3, characterized by that the manufacturing process comprises first adding a thickener to the refrigerated system for thickening and then keeping the refrigerated system warm at 20-30°C for 12-36 h. [5] Manufacturing process according to claim 1, characterized by that before mixing the oil phase solution with the water phase solution, the temperature of the oil phase solution is controlled at 20-22°C. [6] Manufacturing process according to claim 1, characterized by that the emulsification and the addition of the amine solution to the reaction are controlled at 0-5°C. [7] Manufacturing process according to claim 1 or 6, characterized by that the water phase solution is formed by adding the emulsifier to ice water. [8] Manufacturing process according to claim 1, characterized by that the mass ratio of the emulsifier in the water phase solution to the isocyanate monomer in the oil phase solution is 0.01%-5%. [9] Manufacturing process according to claim 1, characterized by that the concentration in mass percent of the amine solution is 5-35%. [10] Manufacturing process according to claim 1, characterized by that the particle size of the microcapsule in the polyurethane microcapsule curing agent is 1-10 µm. [11] Manufacturing process according to claim 1, characterized by that the isocyanate monomer is an isocyanate having at least two isocyanate groups. [12] Manufacturing process according to claim 1 or 11, characterized by that the isocyanate monomer is toluene diisocyanate or diphenylmethane diisocyanate. [13] Manufacturing process according to claim 1, characterized by that a tubular reactor is used for heating and cooling the emulsion, wherein the front section of the tubular reactor is used for heating the emulsion to a set temperature within 1-10 s and the rear section of the tubular reactor is used for cooling the emulsion to a set temperature within 1-10 s. [14] Manufacturing process according to claim 1, characterized by that during emulsification the speed of the corresponding device is 1000-9000 rpm. [15] Manufacturing process according to claim 1, characterized bythat the catalyst is one or a combination of one or more of 4-dimethylaminopyridine, pyridine, tri-tert-butylphosphine, tributylphosphine, triethylenediamine, 2,4,6-tris(dimethylaminomethyl)phenol, bis(dimethylaminoethyl) ether, 1,8-diazabicyclo[5.4.0]undeca-7-N-methylmorpholine, pentamethyldipropylidenediamine, 1-methyl-4-(2-dimethylaminoethyl)piperazine, dimethylaminopyridine, 2,2'-dimorpholine diethyl ether, N,N-dimethylbenzylamine, N,N'-dimethylethanolamine, pentamethyldiethylidenetriamine. [16] Manufacturing process according to claim 1, characterized by that the molar ratio of catalyst to isocyanate monomer is 0.001-0.5%. [17] Manufacturing process according to claim 1, characterized bythat the amine in the amine solution is one or a combination of one or more of ammonia water, urea, ethylenediamine, pentodiamine, hexamethylenediamine, hydrazine hydrate, guanidine, adipic acid dihydrazide, polyetheramine, isophoronediamine, 4,4'-diaminodicyclohexylmethane and diethanolamine. [18] Manufacturing process according to claim 1 or 17, characterized by that the concentration in mass percent of the amine solution is 5-35%. [19] Manufacturing process according to claim 1 or 17, characterized by that the molar ratio of amine to isocyanate monomer in the amine solution is 6-12%. [20] Manufacturing process according to claim 1, characterized by that the emulsifier in the water phase solution is a polyoxyethylene ether-based Span emulsifier and / or a polyoxyethylene ether-based Tween emulsifier. [21] Manufacturing process according to claim , characterized bythat the thickener is one or a combination of one or more of xanthan gum, guar gum, cellulose, polyurethane thickener, polyacrylic acid thickener and polyvinylpyrrolidone. [22] Manufacturing process according to claim 1, characterized by that an antifoam agent is added to the water phase solution during emulsification, wherein the antifoam agent is an organosilicon-based antifoam agent and / or a mineral oil-based antifoam agent. [23] Manufacturing process according to claim 1 or 22, characterized by that the manufacturing process comprises a step of adding a preservative to the system, wherein the preservative is an isothiazolinone fungicide. [24] Process for producing a polyurethane microcapsule curing agent, characterized by that it includes the following steps: Simultaneous mixing of isocyanate monomer and catalyst to form a first solution; adding the first solution to a second solution containing emulsifier to emulsify the first solution so that the first solution forms dispersed droplets; adding the amine solution and mixing; heating the system to 50-80°C within 1-10 s and keeping warm for 1-8 min; cooling to 20-30°C within 1-10 s. [25] A polyurethane microcapsule curing agent produced by a production process according to any one of claims 1 to 24, characterized by that the polyurethane microcapsule curing agent comprises an emulsion and a microcapsule dispersed in the emulsion, wherein the microcapsule comprises a core material having an isocyanate dimer or an isocyanate trimer inside and a wall material formed by the reaction of amine with the isocyanate; and wherein the mass fraction of the microcapsule in the polyurethane microcapsule curing agent is 35-45%. [26] Manufacturing process according to claim 25, characterized by that the polyurethane microcapsule curing agent comprises, by mass percentage, 35-45 parts of microcapsules, 0.1-2 parts of emulsifier, 0.1-0.5 parts of thickener, 0.1-0.5 parts of preservative and 54-65 parts of water. [27] Use of the polyurethane microcapsule curing agent according to claim 25 or 26 in the manufacture of the polyurethane material. [28] Process for producing a polyurethane adhesive, characterized by that it includes the following steps: 1) producing a polyurethane microcapsule curing agent by a production method according to any one of claims 1 to 24; 2) Adding a vinyl acetate-ethylene emulsion to the polyurethane dispersion and adjusting the pH to 6 to 8, adding polyurethane microcapsule curing agent, additive, and water, and stirring to obtain the polyurethane adhesive; wherein the amount of microcapsule curing agent added in the polyurethane adhesive is 3-20%. [29] Manufacturing process according to claim , characterized by that in step 2) the pH value is adjusted with a multifunctional amine additive. [30] Manufacturing process according to claim, characterized by that the additives comprise one or more of a wetting agent, an antifoam agent or a thickener. [31] Manufacturing process according to claim, characterized by that the viscosity of the polyurethane adhesive at 25°C is 1500-3000 mPa·s; the solids content is 35-60%. [32] Manufacturing process according to claim, characterized bythat the polyurethane dispersion is prepared by the following process: heating and dehydrating polyether polyols and / or polyester polyols and extending the chains by adding a chain extender; Adding diisocyanate and catalyst to carry out a reaction until a certain content of isocyanate groups is reached; Adding a solvent to dilute and cool, then adding sodium ethylenediamineethanesulfonate to extend the chain again; Adding tris(hydroxymethyl)aminomethane for capping reaction, then adding water for dispersion, removing the solvent to obtain the polyurethane dispersion. [33] Polyurethane adhesive, characterized bythat the polyurethane adhesive is produced by a production method according to any one of claims 27 to 31, wherein the polyurethane adhesive comprises a polyurethane dispersion and a microcapsule curing agent; and wherein the mass ratio of the polyurethane dispersion to the microcapsule curing agent is 100:5-20. [34] Polyurethane adhesive according to claim 33, characterized by that in mass percentage the polyurethane adhesive comprises 70-85% polyurethane dispersion, 7-12% microcapsule curing agent and 10-18% additive and water. [35] Process for producing a polyurethane adhesive film, characterized by in that it comprises the following steps: producing a polyurethane adhesive by a production method according to any one of claims 28 to 32; applying the polyurethane adhesive to a release paper and drying to obtain the polyurethane adhesive film. [36] Manufacturing process according to claim 35, characterized bythat the drying temperature is lower than 60°C. [37] Polyurethane adhesive, characterized by that the polyurethane adhesive film is produced by a production process according to claim 35 or 36.

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