Polyurethane film-forming agent, polyurethane primer with good storage stability and preparation method

Abstract

The present invention provides a polyurethane film-forming agent and a preparation method thereof. The film-forming agent is mainly prepared by a polymerization reaction of a small molecule triol, a diisocyanate, a diamine component and a color paste. Among them, the small molecule triol is trimethylolpropane, glycerol or any combination of the two. The present invention also provides a polyurethane primer with good storage stability and a preparation method thereof. The primer includes the above-mentioned polyurethane film-forming agent, a TPTI solution, an adhesion promoter and a fifth solvent. Since the color paste is dehydrated during the preparation process of the film-forming agent, rather than a simple direct mixing process, the primer provided by the present invention has good high-temperature storage stability; since the above-mentioned polyurethane film-forming agent, TPTI and adhesion promoter all contain isocyanate groups, the film formed by the above-mentioned polyurethane primer has high strength; at the same time, the high density of silicon-oxygen-carbon bonds in the adhesion promoter is beneficial to improving the low-temperature initial adhesion performance and adhesion strength of the polyurethane adhesive.

Description

Technical Field

[0001] The present invention relates to the technical field of primers for polyurethane adhesives, and specifically relates to a polyurethane film-forming agent, a storage-resistant polyurethane primer, and a preparation method thereof. Background Art

[0002] Polyurethane adhesives have advantages such as high strength and good elasticity, and are widely used in many fields such as automobiles, rail transit, electrical appliances, and buildings. Although polyurethane adhesives contain a large number of active functional groups, can have good bonding performance with the surface of some substrates, and have a high tensile strength, their bonding effect with substrates such as glass, steel, and plastics is poor, and there are also defects in construction performance, so they need to be used in combination with primers.

[0003] Therefore, people hope to develop a suitable primer to improve the bonding effect and construction performance of polyurethane adhesives. For example, Chinese Patent Application CN 111363467 A discloses a primer composition, which contains the following components by mass percentage: the first polyurethane prepolymer 3-10%; the second polyurethane prepolymer 1-15%; the adhesion promoter 0.1-10%; the solvent 6-80%; the additive 1-15%; wherein, the NCO mass percentage content of the first polyurethane prepolymer is 5-10% based on the first polyurethane prepolymer; the NCO mass percentage content of the second polyurethane prepolymer is 2-5% based on the second polyurethane prepolymer. The primer composition disclosed in this patent application, as a special primer for polyurethane sealants, has the characteristics of a wide bonding range, high adhesion to different substrates, a long storage period, fast film formation, high activity, environmental friendliness, and good use effect when used in combination with polyurethane sealants.

[0004] Primers usually have colors during industrial production, and pigments are added thereto. However, when pigments are added to the primer composition disclosed in the above patent application by the existing method, there is a problem that the high-temperature storage performance of the primer is poor. Moreover, when the primer composition disclosed in the above patent application is used in combination with polyurethane sealants to manufacture vehicle windows or insulating glass in winter or at a lower temperature environment, the primer often fails to adhere due to reasons such as poor initial adhesion performance and low initial bonding strength of the polyurethane sealant during the construction process, resulting in problems such as low product yield and high cost. Summary of the Invention

[0005] In view of this, an object of the present invention is to solve the problem of poor high-temperature storage performance of primers; for this purpose, the present invention provides a polyurethane film-forming agent capable of providing the storage performance of primers and a preparation method thereof.

[0006] Another object of the present invention is to solve the problem that polyurethane adhesives are prone to debonding during construction on substrates such as glass, anodized aluminum, and electrophoretic paint steel sheets in winter or at lower temperatures, thereby achieving the purpose of improving product yield and reducing costs. To this end, the present invention also provides a polyurethane primer that has high strength after film formation and is conducive to improving the low-temperature initial adhesion performance and bonding strength of polyurethane adhesives, as well as a preparation method therefor.

[0007] The present invention achieves the above object through the following technical solutions:

[0008] A polyurethane film-forming agent is mainly prepared by polymerizing the following raw materials:

[0009] 100 moles of small molecule triol, 295 - 305 moles of diisocyanate, 5 - 40 moles of diamine, and color paste, and the mass ratio of the total mass of the small molecule triol, diisocyanate, and diamine to the mass of the color paste is 400:120 - 200. Among them, the small molecule triol is trimethylolpropane, glycerol, or any combination of the two.

[0010] The diisocyanate is HDI (1,6 - hexamethylene diisocyanate), IPDI (isophorone diisocyanate), or TDI (toluene diisocyanate). The polyurethane film-forming agent preferably includes IPDI (isophorone diisocyanate).

[0011] The diamine is preferably ethylenediamine, 1,2 - propanediamine, 1,3 - propanediamine, or pentanediamine. The polyurethane film-forming agent preferably includes 5 - 25 moles of diamine.

[0012] The color paste includes the following raw materials in parts by mass: 100 parts of carbon black dispersant solution, 80 - 150 parts of carbon black, and 500 - 700 parts of the first solvent. Among them, the pigment dispersant solvent is prepared by dissolving 100 parts by mass of PB821 in 200 - 300 parts by mass of methyl ethyl ketone. Among them, the first solvent is one or a combination of two of ethyl acetate, butyl acetate, methyl ethyl ketone, toluene, and xylene.

[0013] The color paste is mainly prepared by adding the carbon black dispersant solution, pigment, and the first solvent to a high-speed disperser and stirring at high speed. Preferably, 600 - 900 parts of zirconium beads are added to the high-speed disperser, and the stirring speed of the high-speed disperser is 1500 - 1800 r / min, and the stirring time is 60 - 90 min.

[0014] A preparation method of the above polyurethane film-forming agent, which includes first mixing the small molecule triol, diisocyanate and color paste, dehydrating while the polymerization reaction between the small molecule triol and diisocyanate occurs, and then reacting with diamine. Since the reaction between hydroxyl group and isocyanate group requires a relatively high temperature, while the reaction activity between amino group and isocyanate group is very high, the small molecule triol needs to react with diisocyanate first to avoid the situation that the amino group reacts with diisocyanate first, resulting in too high viscosity of the system during the subsequent hydroxyl group reaction, which requires adding a solvent and causing incomplete reaction.

[0015] Because the color paste contains water, a large amount of solvent, and the carbon black has been ground and dispersed in the solvent, and it is impossible to remove water alone. If the color paste is dehydrated alone, carbon black agglomeration will occur and it cannot be evenly dispersed in the primer again. At the same time, if the color paste and small molecule polyol are dehydrated together, due to the extremely small amount of small molecule polyol, a clumping phenomenon will occur after the solvent in the color paste volatilizes. Therefore, the color paste can only be added to the polymerization reaction system of triol and diisocyanate for dehydration.

[0016] Based on the above, in a nitrogen environment, the small molecule triol, diisocyanate and color paste are mixed and dehydrated under vacuum conditions while undergoing a polymerization reaction, and a second solvent is added for dilution to form a first prepolymer mixed solution; then the diamine dilution solution is added dropwise to the first prepolymer mixed solution for reaction, and then a catalyst is added to continue the reaction to obtain the polyurethane film-forming agent; wherein, the diamine dilution solution is composed of diamine and a third solvent uniformly mixed in a nitrogen atmosphere. The purpose of adding the catalyst in this step is to make the reaction of each raw material complete; the reason for adding the catalyst at the end is that the reaction activity of the amino group is high. If it is added in advance, the reaction will be very violent and not easy to control.

[0017] Among them, the step of forming the first prepolymer mixed solution includes: first dehydrating the small molecule triol at 80°C to 90°C and a vacuum degree lower than -0.095 MPa for 2 to 3 hours, then lowering the temperature to 40°C to 50°C, adding the diisocyanate and color paste under nitrogen protection conditions, and then continuing to dehydrate and react at a vacuum degree lower than -0.095 MPa for 1 to 2 hours, then raising the temperature to 70 to 75°C for reaction for 1 to 2 hours, and then adding the second solvent for dilution for 15 to 45 minutes, and then lowering the temperature to 20°C to 30°C to obtain the first prepolymer mixed solution.

[0018] The steps for preparing the polyurethane film-forming agent include: uniformly diluting diamine with the third solvent in a nitrogen atmosphere to obtain the diamine dilution; slowly dropping the diamine dilution into the first prepolymer mixture, and after the dropping is completed, continuing the reaction for 30 to 60 minutes, then heating to 70 to 75 °C and continuing the reaction for 30 to 60 minutes, and then adding a catalyst and continuing the reaction for 1 to 2 hours.

[0019] To reduce the viscosity of the reaction system to a suitable value, a first solvent is set. Preferably, the dosage of the second solvent is 50% to 100% of the total mass of the small molecule triol and diisocyanate, and the second solvent is one or a combination of two of ethyl acetate, butyl acetate, methyl ethyl ketone, toluene, and xylene.

[0020] To reduce the concentration of diamine and thus control the reaction rate between amino group and isocyanate group, the third solvent is needed to dilute polyamine; preferably, the dosage of the third solvent is 100% to 200% of the mass of diamine. The second solvent is one or a combination of two of ethyl acetate, butyl acetate, methyl ethyl ketone, toluene, and xylene.

[0021] To make the above system react more completely, preferably, the dosage of the catalyst is 0.03% to 0.1% of the total mass of the small molecule triol and diisocyanate. The catalyst is dibutyltin dilaurate or dichlorodibutyltin.

[0022] A storage-stable polyurethane primer, by mass, comprises the following raw materials: 155 parts of the above polyurethane film-forming agent, 20 to 70 parts of triphenyl isocyanate thiophosphate solution, 30 to 80 parts of adhesion aid, and 100 to 300 parts of the fifth solvent.

[0023] Preferably, by mass, the storage-stable polyurethane primer comprises 155 parts of polyurethane film-forming agent, 30 to 60 parts of TPTI, 35 to 60 parts of adhesion aid, and 100 to 220 parts of the fifth solvent.

[0024] Among them, the adhesion aid is a macromolecule containing isocyanate group, silicon-oxy-carbon bond and urea group; such as, diamine silane coupling agent, aminopropyltriethoxysilane, bis-γ-trimethoxysilylpropyl-amine. Preferably, the adhesion aid is mainly prepared by polymerizing HDI biuret and monoamino silane coupling agent. Among them, the molar ratio of HDI biuret to monoamino silane coupling agent is 10:23 to 27; this is to make the adhesion aid contain as much silicon-oxy-carbon structure as possible while having some isocyanate groups, and the subsequent isocyanate groups can form a whole with the film-forming agent and TPTI; preferably, the molar ratio of HDI biuret to monoamino silane coupling agent is 10:25 to 27.

[0025] Specifically, 100 parts by mass of HDI biuret and 50 - 100 parts by mass of the fourth solvent are mixed evenly under nitrogen protection and then placed in a water bath at 20 - 30°C. Under nitrogen protection and stirring, the monoamino silane coupling agent is added dropwise to the water bath. After the addition, stirring is continued for 20 - 40 min, and then the temperature is raised to 60°C - 70°C and the reaction is continued for 1.0 - 2.0 h to prepare the above-mentioned adhesion promoter.

[0026] The monoamino silane coupling agent is one or both of aminopropyltrimethoxysilane and bis(3-trimethoxysilylpropyl)amine, preferably bis(3-trimethoxysilylpropyl)amine.

[0027] Both the fourth solvent and the fifth solvent are a combination of one or two of ethyl acetate, butyl acetate, methyl ethyl ketone, toluene, and xylene.

[0028] Based on the above polyurethane primer, it further includes 3 - 15 parts by mass of glass beads, so as to increase the interfacial area of the primer in contact with air. On the one hand, it makes the solvent in the primer volatilize faster and its surface drying faster. On the other hand, it increases the contact area of the paint film with air, thereby increasing the contact probability with moisture and increasing the low-temperature initial adhesion performance of the primer; in addition, it makes the polyurethane primer have a matte feeling after film formation. Preferably, the polyurethane primer includes 5 - 12 parts by mass of glass beads, and the glass beads are hollow beads with a true density of 0.15 g / cm 3 ~0.70 g / cm 3 and a particle size D90 between 15 microns and 110 microns. Preferably, the glass beads are produced by Zhengzhou Shenglaite Hollow Microsphere New Material Co., Ltd.

[0029] A preparation method of the above polyurethane primer includes: in an inert gas atmosphere, uniformly dispersing other raw materials of the polyurethane primer except the fifth solvent in the fifth solvent. Among them, the inert gas includes nitrogen, helium, neon, argon, xenon, etc. Among them, when adding glass beads in the polyurethane primer system, the glass beads need to be evacuated and heated in a vacuumable container in advance to basically dry the moisture, and then mixed evenly with other substances in a nitrogen environment.

[0030] The above polyurethane film-forming agent provided by the present invention is mainly a high-viscosity body prepared by the reaction of small-molecule trihydric alcohol, diisocyanate, carbon black and diamine, and is a polymer containing a certain amount of ureido groups, a certain amount of isocyanate groups and a large amount of urethane groups. First, the isocyanate groups in trimethylolpropane or glycerol and diisocyanate polymerize according to a molar ratio of about 1:3 to form a first prepolymer molecule containing a large amount of isocyanate groups and a large amount of urethane groups. Then, a small amount of diamine is added to react to further extend the chain of the first prepolymer molecule, forming a polyurethane film-forming agent with a high-viscosity body and basically in a semi-solid state. This film-forming agent is a molecule containing a certain amount of isocyanate groups, a certain amount of ureido groups and a large amount of urethane groups. Since the polyurethane film-forming agent basically does not contain soft segments and all functional groups are structures with relatively high strength, the polyurethane film-forming agent is beneficial to improving the strength of the polyurethane primer; due to its high crosslinking degree, and the molecular weights of the trihydric alcohol and diamine are very small, the prepared product contains a large amount of urethane groups and a certain amount of ureido groups, so its own body viscosity is relatively large.

[0031] Since only water is introduced during the preparation of the color paste in the preparation process of all primers, and this step cannot be heated, evacuated or dehydrated. When preparing the film-forming agent, the color paste is dispersed into the mixture of polyhydric alcohol and isocyanate, and then dehydrated, so that the water content in the whole system can be strictly controlled. Therefore, the storage performance of the polyurethane primer prepared later will be relatively good.

[0032] Therefore, the above polyurethane primer provided by the present invention has the following advantages:

[0033] First, since the color paste is dehydrated during the preparation process of the film-forming agent, rather than a simple direct mixing process, the primer provided by the present invention has good high-temperature storage performance, so that the primer has long-term storage performance.

[0034] Second, the above polyurethane primer has a very high functional group density and extremely high viscosity because its film-forming agent is prepared by the reaction of small-molecule trihydric alcohol and diamine with diisocyanate; at the same time, the added triphenyl isocyanate thiophosphate (TPTI) is a solid and has extremely high activity, and is a trifunctional isocyanate small molecule; the adhesion promoter contains a certain amount of isocyanate groups and has a relatively high viscosity itself. During curing, its isocyanate groups can react with the isocyanate groups in the film-forming agent and triphenyl isocyanate thiophosphate to form a highly crosslinked continuous whole. The combined action of several of them can quickly dry on the surface and crosslink during use, forming a paint film with high strength, and the formed film contains a large amount of ureido groups, which is helpful for bonding to the substrate.

[0035] Third, since the prepared adhesion promoter contains a large amount of silicon oxycarbide structure, a large amount of ureido groups, and a certain amount of isocyanate groups, and its functional group density is also very high. During curing, its isocyanate groups can react with the isocyanate groups in the film-forming agent and triphenyl isocyanate thiophosphate to form a highly cross-linked continuous whole, while introducing a large number of silicon oxycarbide bonds into it. The large number of silicon oxycarbide bonds mainly play a role in reacting with the inorganic interface. By adding dried glass beads, the surface area of the primer increases during the curing process, thereby increasing the contact probability with moisture, increasing the surface drying speed of the primer and the hydrolysis of silicon oxycarbide bonds. Therefore, this polyurethane primer can improve the low-temperature initial adhesion performance and bonding strength of polyurethane adhesives to substrates such as glass, stainless steel, and anodized aluminum, which is beneficial to improving the product yield and construction quality in products such as window manufacturing and insulating glass manufacturing in low-temperature environments, and the cost is low.

[0036] Fourth, during the use of the primer, since the polyurethane film-forming agent used has a relatively high viscosity and is basically in a semi-solid state, on the one hand, it can play a role in quickly drying the surface of the primer, and on the other hand, it can form a continuous film body with relatively high strength, making the primer have high strength after film formation.

[0037] Fifth, since the ureido groups and urethane groups contained in the polyurethane film-forming agent used are beneficial to the adhesion to the substrate, among which part of the amino groups formed by the reaction of isocyanate groups with water during the cross-linking process of the primer do not participate in the film-forming reaction and can react with the polyurethane adhesive, enabling the primer to form an adhesion with the polyurethane adhesive. Specific Embodiments

[0038] The technical solutions of the present invention will be further described in detail below through specific embodiments.

[0039] Examples 1 - 5 Polyurethane Film-Forming Agent

[0040] The raw materials of the polyurethane film-forming agent provided in Examples 1 - 5 of the present invention are mainly shown in Table 1 below.

[0041] Table 1 Raw Material Ratio Table of Polyurethane Film-Forming Agent

[0042]

[0043] Among them, the color paste shown in Examples 1 to 5 was prepared by first adding the carbon black dispersant solution, carbon black, and the first solvent shown in Table 2 by mass parts to a high-speed disperser, and then adding 750 parts of zirconium beads and dispersing for 75 min under the condition of 1650 r / min.

[0044] Table 2 Raw Material Mass Ratio Table of Color Paste

[0045]

[0046] The preparation methods of the polyurethane film-forming agents provided in Examples 1 to 5 are as follows:

[0047] First, trimethylolpropane is dehydrated at 85°C under a vacuum of less than -0.095 MPa for 2.5 h, then the temperature is lowered to about 45°C, and the isocyanate and color paste shown in Table 1 are added under nitrogen protection. Then, dehydration and reaction are continued under a vacuum of less than -0.095 MPa for 1.5 h. After that, the temperature is raised to 75°C and reacted for 1.5 h. Then, a second solvent is added for dilution for 0.5 h. Subsequently, the temperature is lowered to about 25°C to form a first prepolymer mixture; wherein, the amount of the second solvent is 80% of the total mass of trimethylolpropane and the corresponding isocyanate. The second solvent used in Examples 1 to 3 is ethyl acetate, the second solvent used in Example 4 is methyl ethyl ketone, and the second solvent used in Example 5 is toluene;

[0048] The diamine shown in Table 1 is diluted evenly with a third solvent in a nitrogen atmosphere and slowly added dropwise to the above first prepolymer mixture. After the addition is complete, the reaction is continued for about 50 min, then the temperature is raised to 75°C and the reaction is continued for 50 min, and then a catalyst is added and the reaction is continued for 1.5 h; wherein, the amount of the third solvent is 180% of the mass of the diamine. The third solvent used in Examples 1 to 3 is butyl acetate, the third solvent used in Example 4 is toluene, and the third solvent used in Example 5 is ethyl acetate; the amount of the catalyst is 0.05% of the total mass of trimethylolpropane and isocyanate; the catalyst used in Examples 1 to 3 is dibutyltin dilaurate, and the catalysts used in Examples 4 and 5 are dichlorodibutyltin.

[0049] Polyurethane primer for Examples 6 to 10

[0050] The polyurethane primers provided in Examples 6 to 10 of the present invention are mainly obtained by uniformly dispersing the raw materials shown in Table 3 in a fifth solvent in a nitrogen atmosphere.

[0051] Table 3 Mass ratio table of raw materials for adhesion aids

[0052]

[0053] Among them, the raw material compositions of the adhesion aids used in each example in Table 3 are shown in Table 4.

[0054] Table 4 Raw material table for adhesion aids

[0055]

[0056] The "ratio of the two" in Table 4 refers to the molar ratio of HDI biuret to monoaminosilane coupling agent.

[0057] The adhesion aids used in Examples 6 to 10 were prepared by the following method: 100 parts by weight of HDI biuret and 75 parts by weight of the fourth solvent were mixed evenly under nitrogen protection and placed in a water bath at about 25°C. Under nitrogen protection, the monoamino silane coupling agent was added dropwise to the water bath according to the ratio shown in Table 4. After the addition, stirring was continued for about 25 minutes, and then the temperature was raised to about 65°C and the reaction was continued for 1.5 hours.

[0058] Comparative Examples 1 to 3

[0059] Each of Comparative Examples 1 to 3 provided a polyurethane primer, which corresponded to Examples 7, 9, and 10 respectively, and used the same raw materials and ratios. The main difference between the comparative examples and the corresponding examples was that the color paste was not added to the film-forming agent used in the comparative examples. The polyurethane primer provided by the comparative examples was prepared by uniformly dispersing the polyurethane film-forming agent, color paste, triphenyl isocyanurate thiophosphate solution, glass beads, and adhesion aid of the comparative examples in the fifth solvent, and at the same time, the amount of the fifth solvent was correspondingly reduced by the solvent content in the color paste.

[0060] Comparative Example 4

[0061] This comparative example provided a polyurethane primer, and the main difference from the polyurethane primer provided in Example 7 was that: the film-forming agent in this comparative example was the prepolymer of the polyurethane sealant with the same solid content as the film-forming agent provided in Example 2. Specifically, the prepolymer of the polyurethane sealant was prepared from 100 parts by mass of trifunctional polyether polyol 330n with a molecular weight of 5000 and 50 parts by mass of bifunctional polyether polyol 2000D with a molecular weight of 2000. Then, 71.25 parts by mass of the color paste in Example 2 was added, dehydrated at 120°C and under a pressure lower than -0.095 MPa for 2 hours, and then the temperature was lowered to 70°C. 40 parts by mass of MDI was added and reacted for 2 hours, and then 0.1 part by mass of dibutyltin dilaurate was added and the reaction was continued for 2 hours.

[0062] Comparative Example 5

[0063] This comparative example provided a polyurethane primer, and the main difference from the polyurethane primer provided in Example 7 was that: the adhesion aid in this comparative example was γ-glycidoxypropyltrimethoxysilane with the same solid content as the adhesion aid provided in Example 7.

[0064] Comparative Example 6

[0065] This comparative example provided a polyurethane primer, and the main difference from the polyurethane primer provided in Example 9 was that: the adhesion aid in this comparative example was vinyltriethoxysilane with the same solid content as the adhesion aid provided in Example 9.

[0066] Performance Test

[0067] The polyurethane primers provided in Examples 6 to 10 and Comparative Examples 1 to 6 were respectively applied to the surfaces of clean and dry glass of 50 mm × 40 mm × 6 mm and anodized aluminum of 100 mm × 25 mm × 2 mm to form polyurethane primer films. Then, the surface drying time of the polyurethane primer films, the standard condition shear strength, low temperature shear strength, shear performance, etc. of the corresponding polyurethane adhesives were respectively tested, and the results are shown in Table 5.

[0068] 1) Surface drying time: The primer was applied to the surface of 50 mm × 40 mm × 6 mm glass. Under standard conditions, a gauze was used to stick to the primer surface, and the time required for no obvious trace on the paint film surface was taken as the surface drying time.

[0069] 2) Shear test: The polyurethane adhesive (commercially available Huitian 8960H) was coated on the surface of 50 mm × 40 mm × 6 mm glass coated with the primer to a thickness of 3 mm, and the bonding area was 25 mm × 12.5 mm. Then it was pasted onto the surface of 100 mm × 25 mm × 2 mm anodized aluminum coated with the same primer. At the same time, it was cured for 7 days under the standard conditions of 23°C * 50% RH and at low temperature of -5°C, and its shear strength was tested, and its failure mode was observed.

[0070] 3) High temperature storage test: After the polyurethane primer was stored at 70°C * 95% relative humidity for 10 days, the standard condition shear strength of the primer after high temperature storage was tested by the same method as in the above "2) Shear test".

[0071] Table 5 Performance test table of the primer

[0072]

[0073]

[0074] Analysis of the high temperature storage performance test data of Comparative Examples 1 to 3 and Examples 7, 9 and 10 in Table 5 shows that: by dehydrating the color paste during the preparation of the film-forming agent, and dehydrating the glass beads in advance and then mixing them with other substances under nitrogen protection, its high temperature storage performance can be maintained better. Therefore, the polyurethane primer provided in this example has good high temperature storage performance and long-term storage performance.

[0075] It can be seen from Table 5 that: compared with Comparative Example 4, the surface drying time of the polyurethane primer provided in Example 7 is significantly accelerated, which shows that the film-forming agent provided in the embodiments of the present invention is beneficial to accelerating the drying time of the primer.

[0076] Table 5 shows that: compared with Comparative Examples 5 and 6, the drying time of the polyurethane primer provided by Examples 7 and 9 is faster, and the standard condition shear strength and low temperature shear strength of the corresponding polyurethane adhesive are relatively larger. This shows that the adhesion promoter provided by the embodiments of the present invention in combination with the polyurethane film-forming agent is beneficial to enhancing the adhesion strength and low temperature initial adhesion strength of the polyurethane adhesive, improving the construction performance in low temperature environments, and facilitating the shortening of the construction cycle.

[0077] From the shear test data of the substrates shown in Table 5, the polyurethane primer provided by the embodiments of the present invention is beneficial to enhancing the bonding strength of the polyurethane adhesive to substrates such as glass and anodized aluminum.

[0078] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that: it is still possible to modify the specific implementation manners of the present invention or perform equivalent replacements for some technical features; without departing from the spirit of the technical solutions of the present invention, they should all be covered within the scope of the technical solutions claimed by the present invention.

Claims

1. A polyurethane primer with good storage stability, characterized in that, It includes the following raw materials in parts by mass: 155 parts of polyurethane film-forming agent, 20 - 70 parts of triphenyl thiophosphate isocyanate solution, 30 - 80 parts of adhesion promoter, and 100 - 300 parts of the fifth solvent; Among them, the polyurethane film-forming agent is mainly prepared by the following method: First, 100 moles of small molecule trihydric alcohol, 295 - 305 moles of diisocyanate and color paste are mixed, and dehydration is carried out while the small molecule trihydric alcohol and diisocyanate undergo a polymerization reaction; then 5 - 40 moles of diamine are added for reaction, and the mass ratio of the total mass of the small molecule trihydric alcohol, diisocyanate and diamine to the mass of the color paste is 400 : 120 - 200. The small molecule trihydric alcohol is trimethylolpropane, glycerol or any combination of the two; The adhesion promoter is mainly prepared by polymerizing HDI biuret and monoamino silane coupling agent, and the molar ratio of HDI biuret to monoamino silane coupling agent is 10 : 23 - 27.

2. The polyurethane primer according to claim 1, characterized in that: The color paste includes the following raw materials in parts by mass: 100 parts of carbon black dispersant solution, 80 - 150 parts of carbon black, and 500 - 700 parts of the first solvent. Among them, the carbon black dispersant solvent is prepared by dissolving 100 parts by mass of PB821 in 200 - 300 parts by mass of methyl ethyl ketone.

3. The polyurethane primer according to claim 1 or 2, characterized in that: The diamine is ethylenediamine, 1,2 - propanediamine, 1,3 - propanediamine or pentanediamine.

4. The polyurethane primer according to claim 1 or 2, characterized in that: In a nitrogen environment, while the small molecule trihydric alcohol, diisocyanate and color paste undergo a polymerization reaction, vacuum dehydration is carried out, and then a second solvent is added for dilution to form a first prepolymer mixture; then the diamine dilution solution is dropped into the first prepolymer mixture for reaction, and then a catalyst is added to continue the reaction to obtain the polyurethane film-forming agent; among them, the diamine dilution solution is composed of the diamine and a third solvent uniformly mixed in a nitrogen atmosphere.

5. The polyurethane primer according to claim 4, wherein: The dosage of the second solvent is 50% - 100% of the total mass of the small molecule trihydric alcohol and diisocyanate.

6. The polyurethane primer according to claim 4, wherein: The dosage of the third solvent is 100% - 200% of the mass of the diamine.

7. The polyurethane primer according to claim 4, characterized in that: The dosage of the catalyst is 0.03% - 0.1% of the total mass of the small molecule trihydric alcohol and diisocyanate.

8. The polyurethane primer according to claim 1 or 2, characterized in that: It also includes 3 - 15 parts by mass of glass beads.

9. A method for preparing the polyurethane primer according to any one of claims 1 to 8, comprising: In an inert atmosphere environment, the other raw materials of the polyurethane primer except the fifth solvent are uniformly dispersed in the fifth solvent.

Images