A polyurethane coating material and its preparation method and application

Abstract

The present invention discloses a polyurethane coating material, a preparation method and an application thereof, and relates to the technical field of polymer materials. The polyurethane coating material is made of component A and component B in a mass ratio of (120-180): (30-120), wherein: in terms of mass fraction, component A includes: 90-110 parts of a highly active polyether polyol, 2-15 parts of a hydroxyl-terminated triisocyanate containing a dynamic disulfide bond, 2-20 parts of an amine-terminated triisocyanate containing a dynamic diselenide bond, and 2-15 parts of an amine-terminated triisocyanate capable of forming multiple hydrogen bonds; in terms of mass fraction, component B includes: 0-100 parts of a triisocyanate and 0-60 parts of a diisocyanate. The present invention selects highly active polyether polyol and isocyanate as raw materials to prepare a polyurethane material, introduces "multiple self-repairing bonds" into the triisocyanate system, and prepares a two-component, fast-curing, self-repairing polyurethane material.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a polyurethane coating material, a preparation method thereof, and an application thereof. Background Art

[0002] Polyurethane coating materials are widely used in aerospace, military, navigation, civil and other fields due to their multiple advantages such as high gloss, strong adhesion, good temperature resistance, excellent mechanical properties and wide range of applications. Currently, the polyurethane paints on the market have a long curing time during the coating process and are difficult to repair once damaged during use, resulting in a huge waste of resources and environmental pollution. Research on self-healing polyurethane materials is also generally focused on polyurethane elastomers. Generally, the repair effect mainly comes from two parts: non-dynamic covalent bonds and dynamic covalent bonds. Non-dynamic covalent bonds mainly include hydrogen bonds, ionic bonds, π-π bonds and host-guest interactions. Dynamic covalent bonds mainly include disulfide bonds, diselenide bonds, acylhydrazone bonds, urea bonds, siloxane bonds, nitrogen-oxygen bonds, imine bonds, etc. At present, some literature has also reported the self-healing properties of polyurethane paint layers, but they mainly focus on the self-healing of hydrogen bonds and disulfide bonds. At the same time, in traditional dynamic covalent bond self-healing polyurethanes, the dynamic covalent bonds are randomly distributed. Therefore, after the polyurethane material is damaged, it is difficult to ensure that there is a sufficient concentration of dynamic covalent bonds at the gap for repair, resulting in a decrease in the material repair efficiency.

[0003] Currently, there are no reports of polyurethane materials with more than three or four self-healing bonds working together. The combined action of multiple self-healing bonds could significantly improve the material's repair efficiency, shorten repair time, and reduce manufacturing costs, offering broad application prospects. Furthermore, there are no reports of enhanced self-healing properties in fast-curing two-component polyurethane coatings. Summary of the Invention

[0004] In view of the above analysis, the present invention aims to provide a polyurethane coating material, a preparation method and an application thereof, so as to solve at least one of the following existing problems: improving the repair efficiency of the polyurethane coating material after damage, and improving the curing efficiency of the polyurethane coating material during the coating process.

[0005] The purpose of the present invention is mainly achieved through the following technical solutions:

[0006] The present invention provides a polyurethane coating material, which is prepared from component A and component B in a mass ratio of (120-180):(30-120), wherein: in parts by mass, the component A comprises: 90-110 parts of high-activity polyether polyol, 2-15 parts of hydroxyl-terminated triisocyanate containing dynamic disulfide bonds, 2-20 parts of amine-terminated triisocyanate containing dynamic diselenide bonds, and 2-15 parts of amine-terminated triisocyanate capable of forming multiple hydrogen bonds; and in parts by mass, the component B comprises: 0-100 parts of triisocyanate and 0-60 parts of diisocyanate.

[0007] Preferably, in parts by mass, the component A further comprises: 5 to 20 parts of epoxy resin, 0 to 30 parts of diol small molecules, 2 to 21 parts of hydroxyl-terminated triisocyanate containing dynamic carbon-carbon bonds; in parts by mass, the component B further comprises: 0.5 to 5 parts of alkaline catalyst.

[0008] Preferably, in the component A: the hydroxyl-terminated triisocyanate containing a dynamic disulfide bond is prepared by reacting a diol small molecule containing a dynamic disulfide bond with triisocyanate; the amino-terminated triisocyanate containing a dynamic diselenide bond is prepared by reacting a diamine small molecule containing a dynamic diselenide bond with triisocyanate; the hydroxyl-terminated triisocyanate containing a dynamic carbon-carbon bond is prepared by reacting a diol small molecule containing a dynamic carbon-carbon bond with triisocyanate; the amino-terminated triisocyanate capable of forming multiple hydrogen bonds is prepared by reacting a diamine small molecule capable of forming multiple hydrogen bonds with triisocyanate.

[0009] Preferably, the diol small molecule containing a dynamic disulfide bond is selected from at least one of dihydroxyethyl disulfide and dihydroxydiphenyl disulfide; the diamine small molecule containing a dynamic diselenide bond is bis(2-aminophenyl) diselenide; the diol small molecule containing a dynamic carbon-carbon bond is 1,2-bis(4-(2-hydroxyethoxy)phenyl)-1,2-diphenylethane-1,2-diol; and the diamine small molecule capable of forming multiple hydrogen bonds is adipic acid dihydrazide.

[0010] Preferably, the triisocyanate is selected from any one or more of hexamethylene diisocyanate trimer and L-lysine triisocyanate, and the diisocyanate is selected from one or more of hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate and 2,4-toluene diisocyanate.

[0011] Preferably, in the component A: the highly active polyether polyol is selected from any one or more of polyether polyol DEP-330G and polyether polyol DEP-3600H; the epoxy resin is selected from any one or more of bisphenol A epoxy resin E-51 and bisphenol A epoxy resin E-128; the diol small molecule is selected from any one or more of ethylene glycol, diethylene glycol, 1,4-butanediol, and 1,6-hexanediol.

[0012] Preferably, in the B component, the mass fraction of triisocyanate is 10 to 90 parts, and the mass fraction of diisocyanate is 10 to 50 parts.

[0013] The present invention also provides a method for preparing a polyurethane coating material, comprising the following steps: Step 1: Preparation of component A: Evenly mixing a highly active polyether polyol, a hydroxyl-terminated triisocyanate containing a dynamic disulfide bond, an amino-terminated triisocyanate containing a dynamic diselenide bond, and an amino-terminated triisocyanate capable of forming multiple hydrogen bonds at a temperature of 80-100° C. under vacuum conditions; Step 2: Preparation of component B: Evenly mixing the triisocyanate and the diisocyanate; Step 3: Preparation of a polyurethane coating material: Mixing component A and component B at a mass ratio of (120-180):(30-120) at a temperature of 80-100° C., and reacting the component A and the component B to obtain the polyurethane coating material.

[0014] Preferably, in the preparation of the A component, a diol small molecule, an epoxy resin, and a hydroxyl-terminated triisocyanate containing a dynamic carbon-carbon bond are also added; in the preparation of the B component, an alkaline catalyst and an auxiliary agent are also added, and the auxiliary agent is one or more of a defoaming agent, a leveling agent, and a plasticizer.

[0015] The present invention further provides an application of a polyurethane coating material, wherein the polyurethane coating material is used as a paint material for in-mold painting.

[0016] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0017] (1) The polyurethane coating material provided by the present invention introduces a variety of self-repairing bonds such as disulfide bonds, diselenide bonds, carbon-carbon bonds, and hydrogen bonds into the polyurethane material system, and directly bonds small molecules containing self-repairing bonds such as disulfide bonds, diselenide bonds, carbon-carbon bonds, and hydrogen bonds to triisocyanates, so that the self-repairing bonds are concentrated around the triisocyanate as the cross-linking point, presenting a regular distribution state, thereby increasing the local concentration of dynamic covalent bonds. In addition to the repair effect of the self-repairing bonds themselves, the self-repairing bonds also have a synergistic effect, which jointly promotes the repair effect of the material. The self-repairing performance is excellent, the repair time is short, multiple repairs can be performed, the frequency of use is increased, the processing cost is reduced, and the repair conditions are wide, and repair can be performed under heat, light and other conditions.

[0018] (2) The present invention uses highly reactive polyether polyols and isocyanates as raw materials to prepare polyurethane materials. Due to the high activity of the hydroxyl groups in the highly reactive polyether polyols, combined with a composite catalyst, rapid curing of the material is achieved. Furthermore, the addition of the highly reactive polyether polyols imparts excellent mechanical properties and gloss to the polyurethane coating material, achieving an A+ grade surface finish. The method is environmentally friendly and simple.

[0019] (3) The epoxy resin in the polyurethane coating material of the present invention can increase the mechanical strength of the polyurethane coating material and reduce the activity of the hydroxyl groups in the highly active polyether polyol, thereby regulating the reaction rate of the polyurethane.

[0020] (4) The polyurethane coating material provided by the present invention does not require the addition of any solvent and is green and environmentally friendly. In addition, the coating material has many hydrogen bonds, so that the internal structure of the coating material is regularly arranged and has excellent hydrophobic properties, so it is not easy to adhere to impurities such as dust.

[0021] In summary, the polyurethane material provided by the present invention is a polyurethane coating material with adjustable performance designed from the perspectives of raw material selection, molecular design, reaction mechanism, etc., which can not only meet the environmental protection needs of industry development, but also meet the market needs of continuous innovation and development of polyurethane self-healing coating preparation technology.

[0022] Other features and advantages of the present invention will be described in the following description, and part of them will become obvious from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0024] Figure 1 This is a schematic diagram of the exchange between disulfide bonds and diselenide bonds in the polyurethane coating material provided by the present invention under the action of ultraviolet light.

[0025] Figure 2 This is a schematic diagram of the local distribution of dynamic disulfide bonds in the polyurethane coating material provided by the present invention. DETAILED DESCRIPTION

[0026] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used to explain the principles of the present invention together with the embodiments of the present invention.

[0027] The present invention uses triisocyanate, diisocyanate, self-repairing small molecules (for example, small molecules with repair functions containing dynamic disulfide bonds, dynamic diselenide bonds, dynamic carbon-carbon bonds, and multiple hydrogen bonds), highly active polyether polyols, diol small molecules, epoxy resins, additives, catalysts, etc. as raw materials to prepare a polyurethane coating material that can achieve rapid curing and self-repair. The polyurethane coating material is prepared from component A and component B in a mass ratio of (120-180): (30-120), wherein:

[0028] In parts by mass, component A includes:

[0029] Highly active polyether polyol: 90-110 parts,

[0030] Hydroxyl-terminated triisocyanate containing dynamic disulfide bonds: 2 to 15 parts,

[0031] Amine-terminated triisocyanate containing dynamic diselenide bonds: 2 to 20 parts,

[0032] Amine-terminated triisocyanate capable of forming multiple hydrogen bonds: 2 to 15 parts.

[0033] In terms of parts by mass, component B includes:

[0034] Triisocyanate: 0-100 parts,

[0035] Diisocyanate: 0-60 parts.

[0036] It should be noted that during the reaction of components A and B to prepare the polyurethane coating material, the hydroxyl or amine groups in component A react with the triisocyanate and / or diisocyanate in component B to produce the polyurethane coating material. In this polyurethane coating material, the self-healing bonds are concentrated around the triisocyanate crosslinking point, exhibiting a regular distribution. This increases the local concentration of dynamic covalent bonds and further improves the material's repair efficiency. In component B, the triisocyanate has a fast curing rate, and the addition of a diisocyanate can reduce the amount of triisocyanate used, lowering costs and regulating the curing rate.

[0037] Furthermore, in order to further increase the types and concentrations of self-repairing bonds, component A may also include hydroxyl-terminated triisocyanate containing dynamic carbon-carbon bonds, with a mass fraction of 2 to 21 parts.

[0038] It should be noted that the present invention first modifies triisocyanate in the raw material for preparing polyurethane, and directly bonds small molecules containing self-repairing bonds such as disulfide bonds, diselenide bonds, carbon-carbon bonds, hydrogen bonds, etc. to the triisocyanate, so that the self-repairing bonds are concentrated around the triisocyanate as the crosslinking point, showing a regular distribution state, thereby increasing the local concentration of dynamic covalent bonds, thereby further improving the repair efficiency of the polyurethane material. Taking the small molecule modified hexamethylene diisocyanate (HDI) trimer containing dynamic disulfide bonds as an example, the local distribution diagram of the dynamic disulfide bonds is shown as follows: Figure 2 As shown. Figure 2 In the present invention, the isocyanate trimer is first modified by using a small molecule containing a dynamic disulfide bond. The molar ratio of the small molecule containing a dynamic disulfide bond to the isocyanate trimer in the modified isocyanate trimer is 3:1, and the local concentration of the dynamic disulfide bond reaches 300%. The unmodified isocyanate trimer is a mixture of the isocyanate trimer, the small molecule containing a dynamic disulfide bond, and the highly active polyether polyol. Part of the isocyanate trimer reacts with the small molecule containing a dynamic disulfide bond, and part of the isocyanate trimer reacts with the highly active polyether polyol, so that the local average concentration of the dynamic disulfide bond is only 150%.

[0039] In addition, multiple bonds such as disulfide bonds, diselenide bonds, carbon-carbon bonds, and hydrogen bonds are introduced into the polyurethane material system. In addition to the repair effect of the molecules themselves, there is also a synergistic effect between the molecules, which jointly promotes the repair effect of the material. Specifically, under heat or infrared light conditions, hydrogen bonds can promote the flow of polymer molecular chains at the wound, making it easier for the dynamic covalent bonds (dynamic disulfide bonds, dynamic diselenide bonds, and dynamic carbon-carbon bonds) on both sides of the wound to contact and exchange to repair damage; and, disulfide bonds and diselenide bonds can exchange with each other under the action of ultraviolet light, increasing the collision probability of dynamic covalent bonds and improving the repair effect of the material. The exchange effect of disulfide bonds and diselenide bonds under ultraviolet light is as follows. Figure 1 As shown. Figure 1 In the ultraviolet light of 280-390nm, the SS bond and Se-Se bond are opened for exchange, and above the ultraviolet light of 410nm, the SS bond and Se-Se bond are rebonded.

[0040] Furthermore, in order to achieve rapid curing of the polyurethane coating material, improve the mechanical properties of the polyurethane coating material, improve the properties of the polyurethane material, and adjust the reaction rate of component A and component B, and reduce costs, component A can also include the following components expressed in parts by mass: epoxy resin: 5 to 20 parts, diol small molecules: 0 to 30 parts; component B can also include additives and alkaline catalysts, and the additives include defoaming agents, leveling agents, and plasticizers, expressed in parts by mass as follows: defoaming agent: 0.5 to 4 parts, leveling agent: 0.5 to 4 parts, plasticizer: 0.5 to 4 parts, alkaline catalyst: 0.5 to 5 parts.

[0041] It should be noted that the molecular weight of small diol molecules is relatively low, while that of highly reactive polyether polyols is relatively high. The addition of small diol molecules can appropriately adjust the reaction rate of polyurethanes. Furthermore, due to the high activity of the hydroxyl groups in highly reactive polyether polyols, the addition of an appropriate proportion of alkaline catalyst allows for rapid curing of the material. To adjust the reaction rate and mechanical strength of the two-component polyurethane, the present invention also incorporates an epoxy resin. On the one hand, the small amount of hydroxyl groups in the epoxy resin's side chains can react with isocyanate to form a cross-linked interpenetrating network (IPN) with the polyurethane, thereby increasing the mechanical strength of the polyurethane coating. On the other hand, at 80-100°C and in the presence of an alkaline catalyst, the highly reactive hydroxyl groups in the highly reactive polyether polyol can cause the epoxy groups in the epoxy resin to undergo a ring-opening reaction to generate less reactive primary or branched hydroxyl groups, reducing the activity of the hydroxyl groups in the highly reactive polyether polyol and thereby adjusting the reaction rate of the polyurethane. Furthermore, defoamers, leveling agents, and plasticizers can further improve the properties of the polyurethane material.

[0042] Specifically, as a preferred method, the mass ratio of component A to component B is (140-160): (50-100). In terms of mass, component A comprises: 100 parts of high-activity polyether polyol, 10-15 parts of epoxy resin, 5-15 parts of diol small molecule, 6-11 parts of hydroxyl-terminated triisocyanate containing dynamic disulfide bonds, 7-15 parts of amine-terminated triisocyanate containing dynamic diselenide bonds, 5-15 parts of hydroxyl-terminated triisocyanate containing dynamic carbon-carbon bonds, and 4-12 parts of amine-terminated triisocyanate capable of forming multiple hydrogen bonds. Component B comprises: 10-90 parts of triisocyanate, 10-50 parts of diisocyanate, 1.7-2.6 parts of defoamer, 1.7-2.6 parts of leveling agent, 1.7-2.6 parts of plasticizer, and 1.8-3.9 parts of alkaline catalyst.

[0043] Specifically, in component A:

[0044] The highly active polyether polyol can be selected from any one or more of polyether polyol DEP-330G (hydroxyl value = 35 ± 1.5 mgKOH / g, functionality f = 3, molecular weight = 5000 Da, viscosity = 800-1000 mPa·s / 25°C) and polyether polyol DEP-3600H (hydroxyl value = 28 ± 1.5 mgKOH / g, functionality f = 3, molecular weight = 6000 Da, viscosity = 1000-1250 mPa·s / 25°C).

[0045] The epoxy resin may be selected from any one or more of bisphenol A epoxy resin E-51 (solid content = 99.6%, viscosity ≤ 2500 mPas) and bisphenol A epoxy resin E-128 (solid content = 100%, viscosity = 10000-16000 mPas).

[0046] The diol small molecule can be a common diol small molecule, which can be selected from any one or more of ethylene glycol, diethylene glycol, 1,4-butanediol, and 1,6-hexanediol, and is purchased from Shandong Xuchen Chemical Technology Co., Ltd.

[0047] The raw materials for preparing the hydroxyl-terminated triisocyanate containing a dynamic disulfide bond include: a small molecule containing a dynamic disulfide bond, which can be a diol small molecule containing a dynamic disulfide bond, preferably one or more of dihydroxyethyl disulfide and dihydroxydiphenyl disulfide; a triisocyanate, which can be one or more of L-lysine triisocyanate or hexamethylene diisocyanate (HDI) trimer (N3790, N3300, N3600); and a catalyst is preferably dibutyltin dilaurate.

[0048] The raw materials for preparing an amino-terminated triisocyanate containing a dynamic diselenide bond include: a small molecule containing a dynamic diselenide bond, which can be a diamine small molecule containing a dynamic diselenide bond, preferably bis(2-aminophenyl) diselenide; a triisocyanate, which can be one or more of L-lysine triisocyanate or hexamethylene diisocyanate (HDI) trimer (N3790, N3300, N3600); and a catalyst is preferably dibutyltin dilaurate.

[0049] The raw materials for preparing a hydroxyl-terminated triisocyanate containing a dynamic carbon-carbon bond include: a small molecule containing a dynamic carbon-carbon bond, which can be a diol small molecule containing a dynamic carbon-carbon bond, preferably 1,2-bis(4-(2-hydroxyethoxy)phenyl)-1,2-diphenylethane-1,2-diol (DHETPED); a triisocyanate, which can be one or more of L-lysine triisocyanate or hexamethylene diisocyanate (HDI) trimer (N3790, N3300, N3600); and a catalyst is preferably dibutyltin dilaurate.

[0050] The raw materials for preparing an amino-terminated triisocyanate capable of forming multiple hydrogen bonds include: a small molecule capable of forming multiple hydrogen bonds, which may be a diamine small molecule capable of forming multiple hydrogen bonds, preferably adipic acid dihydrazide; a triisocyanate, which may be one or more of L-lysine triisocyanate or hexamethylene diisocyanate (HDI) trimers (N3790, N3300, N3600); and a catalyst preferably is dibutyltin dilaurate.

[0051] Specifically, in component B:

[0052] The triisocyanate may be selected from one or more of hexamethylene diisocyanate (HDI) trimer and L-lysine triisocyanate.

[0053] The diisocyanate can be selected from hexamethylene diisocyanate (HDI), toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate (HMDI), 2,4-toluene diisocyanate or a mixture thereof.

[0054] The defoaming agent may preferably be a composite defoaming agent of organic polyether ester, mineral oil and alcohol. The composite defoaming agent is of model Z-5185, purchased from Shanghai Yuewan New Materials Co., Ltd.

[0055] The leveling agent may preferably be a solvent-free leveling agent, and the type of the solvent-free leveling agent may be selected from FL3750 and At least one of FL 3755, available from BASF.

[0056] The plasticizer may be selected from at least one of dibutyl phthalate, dioctyl phthalate, dibutyl sebacate, dioctyl sebacate, and triethyl citrate.

[0057] The alkaline catalyst is prepared by triethylenediamine and dibutyltin dilaurate in a mass ratio of 2:1, and the amount used is 5‰ to 15‰ of the total mass of the system.

[0058] It should be noted that in component A and component B, the structural formula of the hexamethylene diisocyanate (HDI) trimer is shown in Formula 1, and the structural formula of L-lysine triisocyanate is shown in Formula 2.

[0059] Formula 1:

[0060] Formula 2:

[0061] The present invention also provides a method for preparing a polyurethane coating material, comprising the following steps:

[0062] Step 1: Preparation of component A:

[0063] A hydroxyl-terminated triisocyanate containing a dynamic disulfide bond, an amine-terminated triisocyanate containing a dynamic diselenide bond, a hydroxyl-terminated triisocyanate containing a dynamic carbon-carbon bond, an amine-terminated triisocyanate capable of forming multiple hydrogen bonds, a highly active polyether polyol, a diol small molecule, and an epoxy resin are added to the reaction kettle 1 in sequence according to the above-calculated proportions. The temperature is raised to 80-100° C., the stirring blade speed is adjusted to 700-900 rpm, and the mixture is stirred and vacuumed for 2 h-4 h to mix the raw materials evenly. The mixture is cooled and set aside to obtain component A.

[0064] Step 2: Preparation of component B:

[0065] Add the above-mentioned proportions of triisocyanate, diisocyanate, defoamer, leveling agent, plasticizer and alkaline catalyst into reactor 2, adjust the stirring blade speed to 800 rpm, stir and vacuum for 2-4 hours to mix the materials evenly, and obtain component B.

[0066] Step 3: Preparation of polyurethane coating material:

[0067] The temperature of the reaction kettles 1 and 2 is adjusted to 80° C.-100° C., and the components A and B in the reaction kettles 1 and 2 are mixed at a mixing head so that the component A reacts with the component B to prepare a polyurethane coating material.

[0068] Specifically, in component A, the preparation of the hydroxyl-terminated triisocyanate containing a dynamic disulfide bond is as follows: the amount of hydroxyl group (small molecule containing a dynamic disulfide bond -OH) substance in the small molecule containing a dynamic disulfide bond n1 and the amount of isocyanate group (triisocyanate-NCO) substance in the triisocyanate (n2) are added at a ratio of n1:n2 = (5-7):1, preferably 6:1, so that the small molecule containing a dynamic disulfide bond reacts with the triisocyanate to obtain a hydroxyl-terminated triisocyanate containing a dynamic disulfide bond. The specific preparation method can be: dissolving the small molecule containing a dynamic disulfide bond in N,N-dimethylacetamide solvent, adding dibutyltin dilaurate catalyst, raising the temperature to 80-100 ° C and stirring, slowly adding triisocyanate dropwise within 5-7 hours, continuing stirring for 3-5 hours, and removing the solvent to obtain the product.

[0069] Specifically, in component A, the preparation of the amino-terminated triisocyanate containing a dynamic diselenide bond is as follows: the amount n3 of the amino group (small molecule containing a dynamic diselenide bond -NH2) substance in the small molecule containing a dynamic diselenide bond and the amount n4 of the isocyanate group (triisocyanate-NCO) substance in the triisocyanate are added at a ratio n3:n4 = (5-7):1, preferably 6:1, so that the small molecule containing a dynamic diselenide bond reacts with the triisocyanate to obtain the amino-terminated triisocyanate containing a dynamic diselenide bond. The specific preparation method can be: dissolving the small molecule containing a dynamic diselenide bond in N,N-dimethylacetamide solvent, adding dibutyltin dilaurate catalyst, raising the temperature to 80-100°C and stirring, slowly adding the triisocyanate dropwise within 5-7 hours, continuing stirring for 3-5 hours, and removing the solvent to obtain the product.

[0070] Specifically, in component A, the preparation of the hydroxyl-terminated triisocyanate containing a dynamic carbon-carbon bond is as follows: the amount of hydroxyl groups (small molecules containing dynamic carbon-carbon bonds -OH) in the small molecule containing a dynamic carbon-carbon bond n5 and the amount of isocyanate groups (triisocyanate-NCO) in the triisocyanate n6 are added at a ratio of n5:n6 = (5-7):1, preferably 6:1, so that the small molecule containing a dynamic carbon-carbon bond reacts with the triisocyanate to obtain a hydroxyl-terminated triisocyanate containing a dynamic carbon-carbon bond. The specific preparation method can be: dissolving the small molecule containing a dynamic carbon-carbon bond in N,N-dimethylacetamide solvent, adding dibutyltin dilaurate catalyst, raising the temperature to 80-100 ° C and stirring, slowly adding triisocyanate dropwise within 5-7 hours, continuing stirring for 3-5 hours, and removing the solvent to obtain the product.

[0071] DHETPED, a small molecule diol containing dynamic carbon-carbon bonds, is prepared from the following components: N,N-dimethylformamide (DMF), 4-hydroxybenzophenone (HBP), 2-bromoethanol, anhydrous potassium carbonate, isopropanol, acetic acid, petroleum ether, and ethyl acetate. The specific preparation method is as follows: 4-Hydroxybenzophenone (HBP) is dissolved in N,N-dimethylformamide (DMF), heated to 90°C, 2-bromoethanol is added, and finally, anhydrous potassium carbonate is added as a catalyst. The mixture is reacted under argon for 24 hours. The yellow mixture is then cooled and filtered to remove the solid catalyst. The filtrate is precipitated in deionized water, vacuum filtered, and freeze-dried to obtain white crystals of 4-(2-hydroxyethoxy)benzophenone (HEBP). HEBP is dissolved in DMF, followed by the addition of isopropanol and acetic acid. After mixing, the mixture is irradiated with UV light for 4-6 days and then poured into deionized water to obtain the crude product. Elution was performed by 1:1 petroleum ether-ethyl acetate column chromatography (silica gel) to obtain a small molecule DHETPED containing a dynamic carbon-carbon bond.

[0072] Specifically, in component A, the preparation of the amine-terminated triisocyanate capable of forming multiple hydrogen bonds is as follows: the amount n7 of the amine group (small molecule capable of forming multiple hydrogen bonds -NH2) substance in the small molecule capable of forming multiple hydrogen bonds) and the amount n8 of the isocyanate group (triisocyanate-NCO) substance in the triisocyanate are added in a ratio of n7:n8 = (5-7):1, preferably 6:1, so that the small molecule capable of forming multiple hydrogen bonds reacts with the triisocyanate to prepare the amine-terminated triisocyanate capable of forming multiple hydrogen bonds. The specific preparation method can be: dissolving the small molecule capable of forming multiple hydrogen bonds in N,N-dimethylacetamide solvent, adding dibutyltin dilaurate catalyst, raising the temperature to 80-100°C and stirring, slowly adding the triisocyanate dropwise over 5-7 hours, continuing stirring for 3-5 hours, and removing the solvent to obtain the product.

[0073] It should be noted that there are 3 moles of isocyanate groups in 1 mole of triisocyanate, and at least 6 moles of hydroxyl groups or amine groups are required to cap the triisocyanate, that is, n (small molecule containing a repair bond -OH or -NH2): n (triisocyanate-NCO) = 2:1. However, in order to ensure that each isocyanate group in each triisocyanate molecule is capped with a hydroxyl group or an amine group, and to avoid the bonding of the same small molecule containing a repair bond with the isocyanate groups in different triisocyanate molecules, an excess mole of hydroxyl groups or amine groups can be added. Therefore, the ratio of the amount of hydroxyl groups or amine groups to isocyanate groups can be in the range of (5-7):1, preferably 6:1.

[0074] The present invention also provides an application of a polyurethane coating material, which is used as a paint material for in-mold painting. During the in-mold painting process, the temperatures of reactors 1 and 2 are adjusted to 80°C-90°C, and the mold temperature is adjusted to 90°C-100°C. Components A and B from reactors 1 and 2 are mixed at a mixing head using an injection molding machine and then rapidly injected into a mold system. After curing, the mold is opened to obtain a coated part.

[0075] It should be noted that the present invention selects highly active polyether polyol and isocyanate as raw materials to prepare polyurethane materials. Due to the high activity of the hydroxyl groups in the highly active polyether polyol, it is combined with a composite catalyst in an appropriate proportion to achieve rapid curing of the material. Then, "multiple self-repairing bonds" are introduced into the triisocyanate system to prepare a two-component, fast-curing, self-repairing polyurethane material that can be used for in-mold painting, realizing the combination of "two-component", "fast curing", "rapid self-repair", "Class A surface" and other characteristics. The gel time is 80-150s, the curing time is 7-15min, and the scratch repair time at 100°C is 90-15min.

[0076] The present invention is further illustrated below by means of several specific examples. However, it should be noted that the specific material ratios, process conditions, and results described in the examples of the present invention are only used to illustrate the present invention and are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included within the scope of protection of the present invention.

[0077] Example 1:

[0078] This embodiment provides a polyurethane coating material, a preparation method, and an application thereof.

[0079] The polyurethane coating material is made of component A and component B in a mass ratio of 134.26:51.35, wherein:

[0080] Component A includes the following components expressed in parts by mass:

[0081] Highly active polyether polyol DEP-330G: 100 parts,

[0082] 1,4-Butanediol: 8.8 parts,

[0083] Bisphenol A epoxy resin (E-51): 10 parts,

[0084] Hydroxyl-terminated hexamethylene diisocyanate trimer containing dynamic disulfide bonds: 2.57 parts,

[0085] Amine-terminated hexamethylene diisocyanate trimer containing dynamic diselenide bonds: 4.87 parts,

[0086] Hydroxyl terminated hexamethylene diisocyanate trimer containing dynamic carbon-carbon bonds: 5.21 parts,

[0087] Amine-terminated hexamethylene diisocyanate trimer capable of forming multiple hydrogen bonds: 2.81 parts.

[0088] Component B includes the following components expressed in parts by mass:

[0089] Hexamethylene diisocyanate (HDI) trimer: 44.45 parts,

[0090] Defoaming agent (Z-5185): 1.7 parts,

[0091] Leveling agent( FL 3750): 1.7 parts,

[0092] Plasticizer (dibutyl phthalate): 1.7 parts,

[0093] Catalyst (m(triethylenediamine):m(dibutyltin dilaurate)=2:1)): 1.8 parts.

[0094] This embodiment also provides a method for preparing the polyurethane coating material, comprising the following steps:

[0095] (1) Preparation of component A

[0096] ① Preparation of hydroxyl-terminated hexamethylene diisocyanate trimer containing dynamic disulfide bonds:

[0097] n1 (small molecule -OH containing dynamic disulfide bond): n2 (HDI trimer -NCO) = 6:1.

[0098] In a three-necked flask, 1.8854 g of dihydroxyethyl disulfide (HEDS) was dissolved in 10 ml of N,N-dimethylacetamide solvent, and 5‰ of dibutyltin dilaurate catalyst was added to the total mass of the system. The temperature was raised to 90°C, the stirring paddle speed was 1000 rpm, and 0.6853 g of hexamethylene diisocyanate (HDI) trimer (N3790) was slowly and accurately added dropwise to the three-necked flask within 6 hours through the "polymerization reaction drop control system". Stirring was continued for 4 hours. After removing the solvent, a hydroxyl-terminated HDI trimer containing dynamic disulfide bonds was obtained.

[0099] ② Preparation of amino-terminated hexamethylene diisocyanate trimer containing dynamic diselenide bonds:

[0100] n3 (small molecule containing dynamic diselenide bond -NH2): n4 (HDI trimer -NCO) = 6:1.

[0101] In a three-necked flask, 4.1823 g of bis(2-aminophenyl) diselenide was dissolved in 10 ml of N,N-dimethylacetamide solvent, and 5‰ of dibutyltin dilaurate catalyst was added to the total mass of the system. The temperature was raised to 90°C, the stirring paddle speed was 1000 rpm, and 0.6853 g of hexamethylene diisocyanate (HDI) trimer (N3790) was slowly dripped into the three-necked flask within 6 hours through the "polymerization reaction drop control system". Stirring was continued for 4 hours. After removing the solvent, an amino-terminated HDI trimer containing a dynamic diselenide bond was obtained.

[0102] ③ Preparation of hydroxyl-terminated hexamethylene diisocyanate trimer containing dynamic carbon-carbon bonds:

[0103] n5 (small molecule -OH containing dynamic carbon-carbon bond): n6 (HDI trimer -NCO) = 6:1.

[0104] In a three-necked flask, 4.5226 g of DHETPED was dissolved in 10 ml of N,N-dimethylacetamide solvent, and 5‰ of dibutyltin dilaurate catalyst was added to the total mass of the system. The temperature was raised to 90°C, the stirring paddle speed was 1000 rpm, and 0.6853 g of hexamethylene diisocyanate (HDI) trimer (N3790) was slowly and accurately added dropwise to the three-necked flask within 6 hours through the "polymerization reaction drop control system". Stirring was continued for 4 hours. After removing the solvent, a hydroxyl-terminated HDI trimer containing dynamic carbon-carbon bonds was obtained.

[0105] Among them, the preparation method of the small molecule DHETPED containing dynamic carbon-carbon bonds is as follows: 4-hydroxybenzophenone (HBP) (7.929g, 40mmol) is completely dissolved in 20mL of N,N-dimethylformamide (DMF), heated to 90℃, 2-bromoethanol (7.497g, 60mmol) is added through a separatory funnel, and finally anhydrous potassium carbonate (11.057g, 80mmol) is added as a catalyst. Under argon protection, the reaction is carried out for 24 hours. After that, the yellow mixture is cooled, the solid catalyst is removed by filtration, and the filtrate is precipitated in deionized water, vacuum filtered, and freeze-dried to obtain 4-(2-hydroxyethoxy)benzophenone (HEBP) as white crystals with a yield of 50%; HEBP (4.854g, 20mmol) is dissolved in 20mL of DMF, placed in a 50mL quartz tube, and 30mL of isopropanol and 2 drops of acetic acid are added. After mixing evenly, the reaction is carried out at 350nm, 3-4mW cm -3 The product was irradiated with ultraviolet light for 4-6 days and poured into deionized water to obtain a crude product. The product was eluted by 1:1 petroleum ether-ethyl acetate column chromatography (silica gel) to obtain a small molecule containing a dynamic carbon-carbon bond (DHETPED) with a yield of 31.9%.

[0106] ④ Preparation of amino-terminated hexamethylene diisocyanate trimer capable of forming multiple hydrogen bonds:

[0107] n7 (small molecule that can form multiple hydrogen bonds -NH2):n8 (HDI trimer -NCO) = 6:1.

[0108] In a three-necked flask, 2.1292 g of adipic acid dihydrazide was dissolved in 10 ml of N,N-dimethylacetamide solvent, and 5‰ of dibutyltin dilaurate catalyst was added to the system. The temperature was raised to 90°C, the stirring paddle speed was set at 1000 rpm, and 0.6853 g of hexamethylene diisocyanate (HDI) trimer (N3790) was slowly and accurately added dropwise to the three-necked flask over 6 hours via the "polymerization reaction drop control system". Stirring was continued for 4 hours. After removing the solvent, an amino-terminated HDI trimer capable of forming multiple hydrogen bonds was obtained.

[0109] ⑤ Add 2.57 g of hydroxyl-terminated HDI trimer containing dynamic disulfide bonds, 4.87 g of amine-terminated HDI trimer containing dynamic diselenide bonds, 5.21 g of hydroxyl-terminated HDI trimer containing dynamic carbon-carbon bonds, 2.81 g of amine-terminated HDI trimer capable of forming multiple hydrogen bonds, 100 g of high-activity polyether polyol DEP-330G, 8.8 g of 1,4-butanediol, and 10 g of epoxy resin E-51 to reactor 1 in sequence, raise the temperature to 90 ° C, adjust the stirring paddle speed to 800 rpm, stir and vacuum for 2 h to mix the raw materials evenly, cool down and set aside to obtain component A.

[0110] (2) Preparation of component B

[0111] 44.45g HDI trimer, 1.7g Z-5185, 1.7g FL 3750, 1.7 g of dibutyl phthalate, and 1.8 g of catalyst were added to reactor 2. The stirring blade speed was adjusted to 800 rpm. The mixture was stirred and vacuumed for 2-4 h to mix the materials evenly, thereby obtaining component B.

[0112] (3) Preparation of polyurethane coating material:

[0113] The temperature of the reaction kettles 1 and 2 is adjusted to 80° C.-100° C., and the components A and B in the reaction kettles 1 and 2 are mixed at a mixing head so that the component A reacts with the component B to prepare a polyurethane coating material.

[0114] This embodiment also provides an application of the aforementioned polyurethane coating material for in-mold painting. The temperatures of reactors 1 and 2 were adjusted to 90°C, and the mold temperature was adjusted to 100°C. Materials A and B from reactors 1 and 2 were mixed at the mixing head using an injection molding machine and then rapidly injected into the mold system. After a period of curing, the mold was opened to produce a coated part. The relevant parameters are shown in Table 1.

[0115] Table 1 Sample parameters

[0116] Specification Gel time (s) Curing time (min) Scratch repair time at 100℃ (min) Example 1 80 7 120

[0117] Example 2:

[0118] This embodiment provides a polyurethane coating material, a preparation method, and an application thereof.

[0119] The polyurethane coating material is made of component A and component B in a mass ratio of 177.05:99.64, wherein:

[0120] Component A includes the following components expressed in parts by mass:

[0121] Highly active polyether polyol DEP-330G: 100 parts,

[0122] Bisphenol A epoxy resin (E-128): 15 parts,

[0123] Hydroxyl-terminated hexamethylene diisocyanate trimer containing dynamic disulfide bonds: 10.32 parts,

[0124] Amine-terminated hexamethylene diisocyanate trimer containing dynamic diselenide bonds: 19.54 parts,

[0125] Hydroxyl terminated hexamethylene diisocyanate trimer containing dynamic carbon-carbon bonds: 20.90 parts,

[0126] Amine-terminated hexamethylene diisocyanate trimer capable of forming multiple hydrogen bonds: 11.29 parts.

[0127] Component B includes the following components expressed in parts by mass:

[0128] Hexamethylene diisocyanate (HDI) trimer: 87.94 parts,

[0129] Defoaming agent (Z-5185): 2.6 parts,

[0130] Leveling agent( FL 3755): 2.6 parts,

[0131] Plasticizer (dibutyl phthalate): 2.6 parts,

[0132] Catalyst (m(triethylenediamine):m(dibutyltin dilaurate)=2:1)): 3.9 parts.

[0133] This embodiment also provides a method for preparing the polyurethane coating material, comprising the following steps:

[0134] (1) Preparation of component A

[0135] ① Preparation of hydroxyl-terminated hexamethylene diisocyanate trimer containing dynamic disulfide bonds:

[0136] n1 (small molecule -OH containing dynamic disulfide bond): n2 (HDI trimer -NCO) = 6:1.

[0137] In a three-necked flask, 7.5682 g of dihydroxyethyl disulfide (HEDS) was dissolved in 20 ml of N,N-dimethylacetamide solvent, and 5‰ of dibutyltin dilaurate catalyst was added to the total mass of the system. The temperature was raised to 90°C, the stirring paddle speed was 1000 rpm, and 2.7508 g of hexamethylene diisocyanate (HDI) trimer (N3790) was slowly and accurately added dropwise to the three-necked flask within 6 hours through the "polymerization reaction drop control system". Stirring was continued for 4 hours. After removing the solvent, a hydroxyl-terminated HDI trimer containing dynamic disulfide bonds was obtained.

[0138] ② Preparation of amino-terminated hexamethylene diisocyanate trimer containing dynamic diselenide bonds:

[0139] n3 (small molecule containing dynamic diselenide bond -NH2): n4 (HDI trimer -NCO) = 6:1.

[0140] In a three-necked flask, 16.7878 g of bis(2-aminophenyl) diselenide was dissolved in 20 ml of N,N-dimethylacetamide solvent, and 5‰ of dibutyltin dilaurate catalyst was added to the total mass of the system. The temperature was raised to 90°C, the stirring paddle speed was 1000 rpm, and 2.7508 g of hexamethylene diisocyanate (HDI) trimer (N3790) was slowly and accurately added dropwise to the three-necked flask within 6 hours through the "polymerization reaction drop control system". Stirring was continued for 4 hours. After removing the solvent, an amino-terminated HDI trimer containing a dynamic diselenide bond was obtained.

[0141] ③ Preparation of hydroxyl-terminated hexamethylene diisocyanate trimer containing dynamic carbon-carbon bonds:

[0142] n5 (small molecule -OH containing dynamic carbon-carbon bond): n6 (HDI trimer -NCO) = 6:1.

[0143] In a three-necked flask, 18.1538g of DHETPED was dissolved in 20ml of N,N-dimethylacetamide solvent, and 5‰ of dibutyltin dilaurate catalyst was added. The temperature was raised to 90°C, the stirring speed was set at 1000rpm, and 2.7508g of hexamethylene diisocyanate (HDI) trimer (N3790) was slowly and dropwise added to the flask over 6 hours via the "polymerization reaction dropwise addition control system". Stirring was continued for 4 hours, and the solvent was removed to obtain a hydroxyl-terminated HDI trimer containing dynamic carbon-carbon bonds. The preparation method of the small fraction DHETPED containing dynamic carbon-carbon bonds is described in Example 1.

[0144] ④ Preparation of amino-terminated hexamethylene diisocyanate trimer capable of forming multiple hydrogen bonds:

[0145] n7 (small molecule that can form multiple hydrogen bonds -NH2):n8 (HDI trimer -NCO) = 6:1.

[0146] In a three-necked flask, 8.5468 g of adipic acid dihydrazide was dissolved in 20 ml of N,N-dimethylacetamide solvent, and 5‰ of dibutyltin dilaurate catalyst was added based on the total mass of the system. The temperature was raised to 90°C, the stirring paddle speed was set at 1000 rpm, and 2.7508 g of hexamethylene diisocyanate (HDI) trimer (N3790) was slowly and accurately added dropwise to the three-necked flask over 6 hours via the "polymerization reaction drop control system". Stirring was continued for 4 hours. After removing the solvent, an amino-terminated HDI trimer capable of forming multiple hydrogen bonds was obtained.

[0147] ⑤ 10.32 g of hydroxyl-terminated HDI trimer containing dynamic disulfide bonds, 19.54 g of amine-terminated HDI trimer containing dynamic diselenide bonds, 20.90 g of hydroxyl-terminated HDI trimer containing dynamic carbon-carbon bonds, 11.29 g of amine-terminated HDI trimer capable of forming multiple hydrogen bonds, 100 g of high-activity polyether polyol DEP-330G, and 15 g of epoxy resin E-128 were added to reactor 1 in sequence, the temperature was raised to 90 ° C, the stirring blade speed was adjusted to 800 rpm, and the mixture was stirred and vacuumed for 2 h to mix the raw materials evenly. After cooling, it was set aside to obtain component A.

[0148] (2) Preparation of component B

[0149] 87.94g HDI trimer, 2.6g Z-5185, 2.6g FL 3755, 2.6 g of dibutyl phthalate, and 3.9 g of catalyst were added to reactor 2. The stirring blade speed was adjusted to 800 rpm. The mixture was stirred and vacuumed for 2-4 h to mix the materials evenly, thereby obtaining component B.

[0150] (3) Preparation of polyurethane coating material:

[0151] The temperature of the reaction kettles 1 and 2 is adjusted to 80° C.-100° C., and the components A and B in the reaction kettles 1 and 2 are mixed at a mixing head so that the component A reacts with the component B to prepare a polyurethane coating material.

[0152] This embodiment also provides an application of a polyurethane coating material, which is used as a paint material for in-mold painting.

[0153] The temperatures of reactors 1 and 2 were adjusted to 90°C, and the mold temperature was adjusted to 100°C. Materials A and B from reactors 1 and 2 were mixed at the mixing head using an injection molding machine and then rapidly injected into the mold system. After curing for a period of time, the mold was opened to obtain a coated part. The relevant parameters are shown in Table 2.

[0154] Table 2 Sample parameters

[0155] Specification Gel time (s) Curing time (min) Scratch repair time at 100℃ (min) Example 2 90 8 90

[0156] Example 3:

[0157] This embodiment provides a polyurethane coating material, a preparation method, and an application thereof.

[0158] The polyurethane coating material is made of component A and component B in a mass ratio of 161.78:58.69, wherein:

[0159] Component A includes the following components expressed in parts by mass:

[0160] Highly active polyether polyol DEP-3600H: 100 parts,

[0161] Ethylene glycol: 0.56 parts,

[0162] Bisphenol A epoxy resin (E-51): 15 parts,

[0163] Hydroxyl-terminated hexamethylene diisocyanate trimer containing dynamic disulfide bonds: 8.08 parts,

[0164] Amine-terminated hexamethylene diisocyanate trimer containing dynamic diselenide bonds: 14.51 parts,

[0165] Hydroxyl terminated hexamethylene diisocyanate trimer containing dynamic carbon-carbon bonds: 15.23 parts,

[0166] Amine-terminated hexamethylene diisocyanate trimer capable of forming multiple hydrogen bonds: 8.40 parts.

[0167] Component B includes the following components expressed in parts by mass:

[0168] 4,4'-dicyclohexylmethane diisocyanate (HMDI): 49.19 parts,

[0169] Defoaming agent (Z-5185): 2.1 parts,

[0170] Leveling agent( FL 3750): 2.1 parts,

[0171] Plasticizer (dibutyl phthalate): 2.1 parts,

[0172] Catalyst (m(triethylenediamine):m(dibutyltin dilaurate)=2:1)): 3.2 parts.

[0173] This embodiment also provides a method for preparing the polyurethane coating material, comprising the following steps:

[0174] (1) Preparation of component A

[0175] ① Preparation of hydroxyl-terminated hexamethylene diisocyanate trimer containing dynamic disulfide bonds:

[0176] n1 (small molecule -OH containing dynamic disulfide bond): n2 (HDI trimer -NCO) = 5:1.

[0177] In a three-necked flask, 5.6084 g of dihydroxyethyl disulfide (HEDS) was dissolved in 20 ml of N,N-dimethylacetamide solvent, and 5‰ of dibutyltin dilaurate catalyst was added to the total mass of the system. The temperature was raised to 90°C, the stirring paddle speed was 1000 rpm, and 2.4811 g of hexamethylene diisocyanate (HDI) trimer (N3790) was slowly and accurately added dropwise to the three-necked flask within 6 hours through the "polymerization reaction drop control system". Stirring was continued for 4 hours. After removing the solvent, a hydroxyl-terminated HDI trimer containing dynamic disulfide bonds was obtained.

[0178] ② Preparation of amino-terminated hexamethylene diisocyanate trimer containing dynamic diselenide bonds:

[0179] n3 (small molecule containing dynamic diselenide bond -NH2): n4 (HDI trimer -NCO) = 6:1.

[0180] In a three-necked flask, 12.4405 g of bis(2-aminophenyl) diselenide was dissolved in 20 ml of N,N-dimethylacetamide solvent, and 5‰ of dibutyltin dilaurate catalyst was added to the total mass of the system. The temperature was raised to 90°C, the stirring paddle speed was 1000 rpm, and 2.0676 g of hexamethylene diisocyanate (HDI) trimer (N3790) was slowly and accurately added dropwise to the three-necked flask within 6 hours through the "polymerization reaction drop control system". Stirring was continued for 4 hours. After removing the solvent, an amino-terminated HDI trimer containing a dynamic diselenide bond was obtained.

[0181] ③ Preparation of hydroxyl-terminated hexamethylene diisocyanate trimer containing dynamic carbon-carbon bonds:

[0182] n5 (small molecule -OH containing dynamic carbon-carbon bonds): n6 (HDI trimer -NCO) = 7:1.

[0183] In a three-necked flask, 13.4529g of DHETPED was dissolved in 20ml of N,N-dimethylacetamide solvent, and 5‰ of the total mass of dibutyltin dilaurate catalyst was added. The temperature was raised to 90°C, the stirring speed was set at 1000rpm, and 1.7722g of hexamethylene diisocyanate (HDI) trimer (N3790) was slowly and dropwise added to the three-necked flask over 6 hours via the "polymerization reaction dropwise addition control system". Stirring was continued for 4 hours, and the solvent was removed to obtain a hydroxyl-terminated HDI trimer containing dynamic carbon-carbon bonds. The preparation method of the small fraction DHETPED containing dynamic carbon-carbon bonds is described in Example 1.

[0184] ④ Preparation of amino-terminated hexamethylene diisocyanate trimer capable of forming multiple hydrogen bonds:

[0185] n1 (small molecule that can form multiple hydrogen bonds -NH2):n2 (HDI trimer -NCO) = 6:1.

[0186] In a three-necked flask, 6.3336 g of adipic acid dihydrazide was dissolved in 20 ml of N,N-dimethylacetamide solvent, and 5‰ of dibutyltin dilaurate catalyst was added to the system. The temperature was raised to 90°C, the stirring paddle speed was set at 1000 rpm, and 2.0676 g of hexamethylene diisocyanate (HDI) trimer (N3790) was slowly and accurately added dropwise to the three-necked flask over 6 hours via the "polymerization reaction drop control system". Stirring was continued for 4 hours. After removing the solvent, an amino-terminated HDI trimer capable of forming multiple hydrogen bonds was obtained.

[0187] ⑤ 8.08 g of hydroxyl-terminated HDI trimer containing dynamic disulfide bonds, 14.51 g of amine-terminated HDI trimer containing dynamic diselenide bonds, 15.23 g of hydroxyl-terminated HDI trimer containing dynamic carbon-carbon bonds, 8.40 g of amine-terminated HDI trimer capable of forming multiple hydrogen bonds, 100 g of high-activity polyether polyol DEP-3600H, 0.56 g of ethylene glycol, and 15 g of epoxy resin E-51 were added to reactor 1 in sequence, the temperature was raised to 90 ° C, the stirring blade speed was adjusted to 800 rpm, and the mixture was stirred and vacuumed for 2 h to mix the raw materials evenly. After cooling, it was set aside to obtain component A.

[0188] (2) Preparation of component B

[0189] 49.19g of HMDI, 2.1g of Z-5185, 2.1g of FL 3750, 2.1 g of dibutyl sebacate, and 3.2 g of catalyst were added to reactor 2. The stirring blade speed was adjusted to 800 rpm. The mixture was stirred and vacuumed for 2-4 h to mix the materials evenly, thereby obtaining component B.

[0190] (3) Preparation of polyurethane coating material:

[0191] The temperature of the reaction kettles 1 and 2 is adjusted to 80° C.-100° C., and the components A and B in the reaction kettles 1 and 2 are mixed at a mixing head so that the component A reacts with the component B to prepare a polyurethane coating material.

[0192] This embodiment also provides an application of a polyurethane coating material, which is used as a paint material for in-mold painting.

[0193] The temperatures of reactors 1 and 2 were adjusted to 90°C, and the mold temperature was adjusted to 100°C. Materials A and B from reactors 1 and 2 were mixed at the mixing head using an injection molding machine and then rapidly injected into the mold system. After curing for a period of time, the mold was opened to obtain a coated part. The relevant parameters are shown in Table 3.

[0194] Table 3 Sample parameters

[0195] Specification Gel time (s) Curing time (min) Scratch repair time at 100℃ (min) Example 3 150 15 240

[0196] Example 4:

[0197] This embodiment provides a polyurethane coating material, a preparation method, and an application thereof.

[0198] The polyurethane coating material is made of component A and component B in a mass ratio of 145.79:39.78, wherein:

[0199] Component A includes the following components expressed in parts by mass:

[0200] Highly active polyether polyol DEP-3600H: 100 parts,

[0201] 1,4-Butanediol: 13.72 parts,

[0202] Bisphenol A epoxy resin (E-51): 10 parts,

[0203] Hydroxyl-terminated L-lysine triisocyanate containing dynamic disulfide bonds: 3.50 parts,

[0204] Amine-terminated L-lysine triisocyanate containing dynamic diselenide bonds: 7.08 parts,

[0205] Hydroxyl terminated L-lysine triisocyanate containing dynamic carbon-carbon bonds: 7.61 parts,

[0206] Amine-terminated L-lysine triisocyanate capable of forming multiple hydrogen bonds: 3.88 parts.

[0207] Component B includes the following components expressed in parts by mass:

[0208] L-lysine triisocyanate: 32.58 parts,

[0209] Defoaming agent (Z-5185): 1.8 parts,

[0210] Leveling agent( FL 3755): 1.8 parts,

[0211] Plasticizer (dioctyl phthalate): 1.8 parts,

[0212] Catalyst (m(triethylenediamine):m(dibutyltin dilaurate)=2:1)): 1.8 parts.

[0213] This embodiment also provides a method for preparing the polyurethane coating material, comprising the following steps:

[0214] (1) Preparation of component A

[0215] ① Preparation of hydroxyl-terminated L-lysine triisocyanate containing dynamic disulfide bonds:

[0216] n1 (small molecule -OH containing dynamic disulfide bond): n2 (L-lysine triisocyanate -NCO) = 6:1.

[0217] In a three-necked flask, 2.9350 g of dihydroxyethyl disulfide (HEDS) was dissolved in 10 ml of N,N-dimethylacetamide solvent, and 5‰ of dibutyltin dilaurate catalyst was added based on the total mass of the system. The temperature was raised to 90°C, the stirring speed was set at 1000 rpm, and 0.5650 g of L-lysine triisocyanate was slowly and accurately added dropwise to the three-necked flask within 6 hours through the "polymerization reaction drop control system". Stirring was continued for 4 hours. After removing the solvent, hydroxyl-terminated L-lysine triisocyanate containing dynamic disulfide bonds was obtained.

[0218] ② Preparation of amino-terminated L-lysine triisocyanate containing dynamic diselenide bond:

[0219] n3 (small molecule containing dynamic diselenide bond -NH2): n4 (L-lysine triisocyanate -NCO) = 6:1.

[0220] In a three-necked flask, 6.5104 g of bis(2-aminophenyl) diselenide was dissolved in 10 ml of N,N-dimethylacetamide solvent, and 5‰ of dibutyltin dilaurate catalyst was added based on the total mass of the system. The temperature was raised to 90°C, the stirring paddle speed was 1000 rpm, and 0.5650 g of L-lysine triisocyanate was slowly dripped into the three-necked flask within 6 hours through the "polymerization reaction drop control system". Stirring was continued for 4 hours. After removing the solvent, amino-terminated L-lysine triisocyanate containing a dynamic diselenide bond was obtained.

[0221] ③ Preparation of hydroxyl-terminated L-lysine triisocyanate containing dynamic carbon-carbon bonds:

[0222] n5 (small molecule -OH containing a dynamic carbon-carbon bond): n6 (L-lysine triisocyanate -NCO) = 6:1.

[0223] In a three-necked flask, 7.0402g of DHETPED was dissolved in 10ml of N,N-dimethylacetamide solvent. 5‰ of dibutyltin dilaurate catalyst was added. The temperature was raised to 90°C, and the stirring speed was set at 1000rpm. Using the "polymerization reaction dropwise addition control system," 0.5650g of L-lysine triisocyanate was slowly and precisely added dropwise to the flask over 6 hours. Stirring was continued for 4 hours. After removing the solvent, hydroxyl-terminated L-lysine triisocyanate containing dynamic carbon-carbon bonds was obtained. The preparation method of the small fraction DHETPED containing dynamic carbon-carbon bonds was described in Example 1.

[0224] ④ Preparation of amino-terminated L-lysine triisocyanate capable of forming multiple hydrogen bonds:

[0225] n1 (small molecule that can form multiple hydrogen bonds -NH2):n2 (L-lysine triisocyanate -NCO) = 6:1.

[0226] In a three-necked flask, 3.3145 g of adipic acid dihydrazide was dissolved in 10 ml of N,N-dimethylacetamide solvent, and 5‰ of dibutyltin dilaurate catalyst was added based on the total mass of the system. The temperature was raised to 90°C, and the stirring paddle speed was set at 1000 rpm. 0.5650 g of L-lysine triisocyanate was slowly and accurately added dropwise to the three-necked flask over 6 hours via the "polymerization reaction drop control system". Stirring was continued for 4 hours. After removing the solvent, amino-terminated L-lysine triisocyanate capable of forming multiple hydrogen bonds was obtained.

[0227] ⑤ 3.50 g of hydroxyl-terminated L-lysine triisocyanate containing a dynamic disulfide bond, 7.08 g of amine-terminated L-lysine triisocyanate containing a dynamic diselenide bond, 7.61 g of hydroxyl-terminated L-lysine triisocyanate containing a dynamic carbon-carbon bond, 3.88 g of amine-terminated L-lysine triisocyanate capable of forming multiple hydrogen bonds, 100 g of highly active polyether polyol DEP-3600H, 13.72 g of 1,4-butanediol, and 10 g of epoxy resin E-51 were added to reactor 1 in sequence, the temperature was raised to 90 ° C, the stirring blade speed was adjusted to 800 rpm, and the mixture was stirred and vacuumed for 2 h to mix the raw materials evenly. After cooling, it was set aside to obtain component A.

[0228] (2) Preparation of component B

[0229] 32.58g of L-lysine triisocyanate, 1.8g of Z-5185, 1.8g of FL 3755, 1.8 g of dioctyl phthalate, and 1.8 g of catalyst were added to reactor 2. The stirring blade speed was adjusted to 800 rpm. The mixture was stirred and vacuumed for 2-4 h to mix the materials evenly, thereby obtaining component B.

[0230] (3) Preparation of polyurethane coating material:

[0231] The temperature of the reaction kettles 1 and 2 is adjusted to 80° C.-100° C., and the components A and B in the reaction kettles 1 and 2 are mixed at a mixing head so that the component A reacts with the component B to prepare a polyurethane coating material.

[0232] This embodiment also provides an application of a polyurethane coating material, which is used as a paint material for in-mold painting.

[0233] The temperatures of reactors 1 and 2 were adjusted to 80°C, and the mold temperature was adjusted to 90°C. Materials A and B from reactors 1 and 2 were mixed at the mixing head using the injection molding machine and then rapidly injected into the mold system. After curing for a period of time, the mold was opened to obtain the coated part. The relevant parameters are shown in Table 4.

[0234] Table 4 Sample parameters

[0235] Specification Gel time (s) Curing time (min) Scratch repair time at 100℃ (min) Example 4 110 12 130

[0236] Example 5:

[0237] This embodiment provides a polyurethane coating material, a preparation method, and an application thereof.

[0238] The polyurethane coating material is made of component A and component B in a mass ratio of 151.36:40.57, wherein:

[0239] Component A includes the following components expressed in parts by mass:

[0240] Highly active polyether polyol DEP-3600H: 100 parts,

[0241] 1,6-hexanediol: 5.76 parts,

[0242] Bisphenol A epoxy resin (E-51): 15 parts,

[0243] Hydroxyl-terminated L-lysine triisocyanate containing dynamic disulfide bonds: 6.83 parts,

[0244] Amine-terminated L-lysine triisocyanate containing dynamic diselenide bonds: 9.06 parts,

[0245] Hydroxyl terminated L-lysine triisocyanate containing dynamic carbon-carbon bonds: 9.74 parts,

[0246] Amine-terminated L-lysine triisocyanate capable of forming multiple hydrogen bonds: 4.97 parts.

[0247] Component B includes the following components expressed in parts by mass:

[0248] L-lysine triisocyanate: 16.06 parts,

[0249] 2,4-Toluene diisocyanate: 16.41,

[0250] Defoaming agent (Z-5185): 1.8 parts,

[0251] Leveling agent( FL 3750): 1.8 parts,

[0252] Plasticizer (dioctyl sebacate): 1.8 parts,

[0253] Catalyst (m(triethylenediamine):m(dibutyltin dilaurate)=2:1)): 2.7 parts.

[0254] This embodiment also provides a method for preparing the polyurethane coating material, comprising the following steps:

[0255] (1) Preparation of component A

[0256] ① Preparation of hydroxyl-terminated L-lysine triisocyanate containing dynamic disulfide bonds:

[0257] n1 (small molecule -OH containing dynamic disulfide bond): n2 (L-lysine triisocyanate -NCO) = 6:1.

[0258] In a three-necked flask, 6.1034 g of dihydroxydiphenyl disulfide was dissolved in 20 ml of N,N-dimethylacetamide solvent, and 5‰ of the total mass of the system was added as a dibutyltin dilaurate catalyst. The temperature was raised to 90°C, the stirring paddle speed was 1000 rpm, and 0.7239 g of L-lysine triisocyanate was slowly and accurately added dropwise into the three-necked flask within 6 hours through the "polymerization reaction drop control system". Stirring was continued for 4 hours. After removing the solvent, hydroxyl-terminated L-lysine triisocyanate containing dynamic disulfide bonds was obtained.

[0259] ② Preparation of amino-terminated L-lysine triisocyanate containing dynamic diselenide bond:

[0260] n3 (small molecule containing dynamic diselenide bond -NH2): n4 (L-lysine triisocyanate -NCO) = 6:1.

[0261] In a three-necked flask, 8.3420 g of bis(2-aminophenyl) diselenide was dissolved in 10 ml of N,N-dimethylacetamide solvent, and 5‰ of dibutyltin dilaurate catalyst was added based on the total mass of the system. The temperature was raised to 90°C, the stirring paddle speed was 1000 rpm, and 0.7239 g of L-lysine triisocyanate was slowly and accurately added dropwise into the three-necked flask within 6 hours through the "polymerization reaction drop control system". Stirring was continued for 4 hours. After removing the solvent, amino-terminated L-lysine triisocyanate containing a dynamic diselenide bond was obtained.

[0262] ③ Preparation of hydroxyl-terminated L-lysine triisocyanate containing dynamic carbon-carbon bonds:

[0263] n5 (small molecule -OH containing a dynamic carbon-carbon bond): n6 (L-lysine triisocyanate -NCO) = 6:1.

[0264] In a three-necked flask, 9.0208g of DHETPED was dissolved in 10ml of N,N-dimethylacetamide solvent. 5‰ of dibutyltin dilaurate catalyst was added. The temperature was raised to 90°C, and the stirring speed was set at 1000 rpm. Using the "polymerization reaction dropwise addition control system," 0.7239g of L-lysine triisocyanate was added over 6 hours. Stirring was continued for 4 hours. After removing the solvent, hydroxyl-terminated L-lysine triisocyanate containing dynamic carbon-carbon bonds was obtained. The preparation method of the small fraction DHETPED containing dynamic carbon-carbon bonds was similar to that in Example 1.

[0265] ④ Preparation of amino-terminated L-lysine triisocyanate capable of forming multiple hydrogen bonds:

[0266] n7 (small molecule -NH2 that can form multiple hydrogen bonds): n8 (L-lysine triisocyanate -NCO) = 6:1.

[0267] In a three-necked flask, 4.2471 g of adipic acid dihydrazide was dissolved in 10 ml of N,N-dimethylacetamide solvent, and 5‰ of dibutyltin dilaurate catalyst was added based on the total mass of the system. The temperature was raised to 90°C, and the stirring paddle speed was set at 1000 rpm. 0.7239 g of L-lysine triisocyanate was slowly and accurately added dropwise to the three-necked flask over 6 hours via the "polymerization reaction dropwise addition control system." Stirring was continued for 4 hours. After removing the solvent, amino-terminated L-lysine triisocyanate capable of forming multiple hydrogen bonds was obtained.

[0268] ⑤ 6.83 g of hydroxyl-terminated L-lysine triisocyanate containing a dynamic disulfide bond, 9.06 g of amine-terminated L-lysine triisocyanate containing a dynamic diselenide bond, 9.74 g of hydroxyl-terminated L-lysine triisocyanate containing a dynamic carbon-carbon bond, 4.97 g of amine-terminated L-lysine triisocyanate capable of forming multiple hydrogen bonds, 100 g of highly active polyether polyol DEP-3600H, 5.76 g of 1,6-hexanediol, and 15 g of epoxy resin E-51 were added to reactor 1 in sequence, the temperature was raised to 90 ° C, the stirring blade speed was adjusted to 800 rpm, and the mixture was stirred and vacuumed for 2 h to mix the raw materials evenly. After cooling, it was set aside to obtain component A.

[0269] (2) Preparation of component B

[0270] 16.06g of L-lysine triisocyanate, 16.41g of 2,4-toluene diisocyanate, 1.8g of Z-5185, 1.8g of FL 3750, 1.8 g of dioctyl sebacate, and 2.7 g of catalyst were added to reactor 2. The stirring blade speed was adjusted to 800 rpm. The mixture was stirred and vacuumed for 2-4 h to mix the materials evenly, thereby obtaining component B.

[0271] (3) Preparation of polyurethane coating material:

[0272] The temperature of the reaction kettles 1 and 2 is adjusted to 80° C.-100° C., and the components A and B in the reaction kettles 1 and 2 are mixed at a mixing head so that the component A reacts with the component B to prepare a polyurethane coating material.

[0273] This embodiment also provides an application of a polyurethane coating material, which is used as a paint material for in-mold painting.

[0274] The temperatures of reactors 1 and 2 were adjusted to 80°C, and the mold temperature was adjusted to 90°C. Materials A and B from reactors 1 and 2 were mixed at the mixing head using the injection molding machine and then rapidly injected into the mold system. After curing for a period of time, the mold was opened to obtain the coated part. The relevant parameters are shown in Table 5.

[0275] Table 5 Sample parameters

[0276] Specification Gel time (s) Curing time (min) Scratch repair time at 100℃ (min) Example 5 100 10 150

[0277] Comparative Example 1:

[0278] This comparative example provides a polyurethane coating material, a preparation method and an application thereof.

[0279] The polyurethane coating material is made of component A and component B in a mass ratio of 166.05 / 110.64, wherein:

[0280] Component A includes the following components expressed in parts by mass:

[0281] Highly active polyether polyol DEP-330G: 100 parts,

[0282] Bisphenol A epoxy resin (E-128): 15 parts,

[0283] Dihydroxyethyl disulfide: 7.57 parts,

[0284] Bis(2-aminophenyl) diselenide: 16.79 parts,

[0285] 1,2-bis(4-(2-hydroxyethoxy)phenyl)-1,2-diphenylethane-1,2-diol: 18.15 parts,

[0286] Adipic acid dihydrazide: 8.54 parts.

[0287] Component B includes the following components expressed in parts by mass:

[0288] Hexamethylene diisocyanate (HDI) trimer: 98.94 parts,

[0289] Defoaming agent (Z-5185): 2.6 parts,

[0290] Leveling agent( FL 3755): 2.6 parts,

[0291] Plasticizer (dibutyl phthalate): 2.6 parts,

[0292] Catalyst (m(triethylenediamine):m(dibutyltin dilaurate)=2:1)): 3.9 parts.

[0293] This comparative example also provides a method for preparing the above-mentioned polyurethane coating material, comprising the following steps:

[0294] (1) Preparation of component A

[0295] 7.57 g of dihydroxyethyl disulfide, 16.79 g of bis(2-aminophenyl) diselenide, 18.15 g of 1,2-bis(4-(2-hydroxyethoxy)phenyl)-1,2-diphenylethane-1,2-diol, 8.54 g of adipic acid dihydrazide, 100 g of high-activity polyether polyol DEP-330G, and 15 g of epoxy resin E-128 were added to reactor 1 in sequence, the temperature was raised to 90°C, the stirring paddle speed was adjusted to 800 rpm, stirred and vacuumed for 2 h to mix the raw materials evenly, cooled and set aside to obtain component A.

[0296] (2) Preparation of component B

[0297] 98.94g hexamethylene diisocyanate (HDI) trimer, 2.6g defoamer (Z-5185), 2.6g leveling agent ( FL 3755), 2.6 g of plasticizer (dibutyl phthalate), and 3.9 g of catalyst were added to reactor 2, and the stirring blade speed was adjusted to 800 rpm. The mixture was stirred and vacuumed for 2 h to 4 h to mix the materials evenly to obtain component B.

[0298] (3) Preparation of polyurethane coating material:

[0299] The temperature of the reaction kettles 1 and 2 is adjusted to 80° C.-100° C., and the components A and B in the reaction kettles 1 and 2 are mixed at a mixing head so that the component A reacts with the component B to prepare a polyurethane coating material.

[0300] This comparative example also provides an application of a polyurethane coating material for in-mold painting.

[0301] The temperatures of Reactors 1 and 2 were adjusted to 90°C, and the mold temperature was adjusted to 100°C. Materials A and B from Reactors 1 and 2 were mixed at the mixing head using the injection molding machine and then rapidly injected into the mold system. After curing for a period of time, the mold was opened to obtain the coated part. The relevant parameters are shown in Table 6.

[0302] Compared with Example 2, the small molecule containing dynamic bonds in Example 2 has already reacted with triisocyanate in advance. This comparative example only uses a small molecule containing a repair bond, and does not bond the small molecule containing the repair bond to the triisocyanate. The gel time and curing time are long, the self-repair bonds are irregularly distributed, the local concentration is low, the scratch repair time at 100°C is significantly increased, and the repair speed is slow.

[0303] Table 6 Sample parameters

[0304] Specification Gel time (s) Curing time (min) Scratch repair time at 100℃ (min) Comparative Example 1 300 75 600

[0305] Comparative Example 2:

[0306] This comparative example provides a polyurethane coating material, a preparation method and an application thereof.

[0307] The polyurethane coating material is made of component A and component B in a mass ratio of 121.39 / 62.17, wherein:

[0308] Component A includes the following components expressed in parts by mass:

[0309] Highly active polyether polyol DEP-330G: 100 parts,

[0310] Bisphenol A epoxy resin (E-51): 10 parts,

[0311] 1,4-Butanediol: 11.39 parts.

[0312] Component B includes the following components expressed in parts by mass:

[0313] Hexamethylene diisocyanate (HDI) trimer: 55.27 parts,

[0314] Defoaming agent (Z-5185): 1.7 parts,

[0315] Leveling agent( FL 3750): 1.7 parts,

[0316] Plasticizer (dibutyl phthalate): 1.7 parts,

[0317] Catalyst (m(triethylenediamine):m(dibutyltin dilaurate)=2:1)): 1.8 parts.

[0318] This comparative example also provides a method for preparing the above-mentioned polyurethane coating material, comprising the following steps:

[0319] (1) Preparation of component A

[0320] 11.39 g of 1,4-butanediol, 100 g of highly active polyether polyol DEP-330G, and 10 g of epoxy resin E-51 were added to reactor 1 in sequence, the temperature was raised to 90°C, the stirring blade speed was adjusted to 800 rpm, and the mixture was stirred and vacuumed for 2 h to mix the raw materials evenly. The mixture was cooled and set aside to obtain component A.

[0321] (2) Preparation of component B

[0322] 55.27g hexamethylene diisocyanate (HDI) trimer, 1.7g defoamer (Z-5185), 1.7g leveling agent ( FL 3750), 1.7 g of plasticizer (dibutyl phthalate), and 1.8 g of catalyst were added to reactor 2, and the stirring blade speed was adjusted to 800 rpm. The mixture was stirred and vacuumed for 2 h to 4 h to mix the materials evenly to obtain component B.

[0323] (3) Preparation of polyurethane materials:

[0324] The temperature of the reaction kettles 1 and 2 is adjusted to 80° C.-100° C., and the components A and B in the reaction kettles 1 and 2 are mixed at a mixing head so that the component A reacts with the component B to prepare a polyurethane material.

[0325] This comparative example also provides an application of a polyurethane coating material for in-mold painting.

[0326] The temperatures of Reactors 1 and 2 were adjusted to 90°C, and the mold temperature was adjusted to 100°C. Materials A and B from Reactors 1 and 2 were mixed at the mixing head using the injection molding machine and then rapidly injected into the mold system. After curing for a period of time, the mold was opened to obtain the coated part. The relevant parameters are shown in Table 7.

[0327] Compared with Example 1, this comparative example does not use small molecules containing repair bonds, the gel time and curing time are longer, and the scratches cannot be repaired.

[0328] Table 7 Sample parameters

[0329] Specification Gel time (s) Curing time (min) Scratch repair time at 100℃ (min) Comparative Example 2 280 60 No change

[0330] Comparative Example 3

[0331] This comparative example provides a polyurethane coating material, a preparation method and an application thereof.

[0332] The polyurethane coating material is made of component A and component B in a mass ratio of 156.28:99.64, wherein:

[0333] Component A includes the following components expressed in parts by mass:

[0334] Highly active polyether polyol DEP-330G: 100 parts,

[0335] Bisphenol A epoxy resin (E-128): 15 parts,

[0336] Hydroxyl-terminated hexamethylene diisocyanate trimer containing dynamic disulfide bonds: 41.28 parts.

[0337] Component B includes the following components expressed in parts by mass:

[0338] Hexamethylene diisocyanate (HDI) trimer: 87.94 parts,

[0339] Defoaming agent (Z-5185): 2.6 parts,

[0340] Leveling agent( FL 3755): 2.6 parts,

[0341] Plasticizer (dibutyl phthalate): 2.6 parts,

[0342] Catalyst (m(triethylenediamine):m(dibutyltin dilaurate)=2:1)): 3.9 parts.

[0343] This embodiment also provides a method for preparing the polyurethane coating material, comprising the following steps:

[0344] (1) Preparation of component A

[0345] ① Preparation of hydroxyl-terminated hexamethylene diisocyanate trimer containing dynamic disulfide bonds:

[0346] n1 (small molecule -OH containing dynamic disulfide bond): n2 (HDI trimer -NCO) = 6:1.

[0347] In a three-necked flask, 30.2728 g of dihydroxyethyl disulfide (HEDS) was dissolved in 80 ml of N,N-dimethylacetamide solvent, and 5‰ of dibutyltin dilaurate catalyst was added to the total mass of the system. The temperature was raised to 90°C, the stirring paddle speed was 1000 rpm, and 11.0032 g of hexamethylene diisocyanate (HDI) trimer (N3790) was slowly and accurately added dropwise to the three-necked flask within 6 hours through the "polymerization reaction drop control system". Stirring was continued for 4 hours. After removing the solvent, a hydroxyl-terminated HDI trimer containing dynamic disulfide bonds was obtained.

[0348] ② Add 41.28g of hydroxyl-terminated HDI trimer containing dynamic disulfide bonds, 100g of highly active polyether polyol DEP-330G, and 15g of epoxy resin E-128 to reactor 1 in sequence, raise the temperature to 90°C, adjust the stirring blade speed to 800rpm, stir and vacuum for 2h to mix the raw materials evenly, cool down and set aside to obtain component A.

[0349] (2) Preparation of component B

[0350] 87.94g HDI trimer, 2.6g Z-5185, 2.6g FL 3755, 2.6 g of dibutyl phthalate, and 3.9 g of catalyst were added to reactor 2. The stirring blade speed was adjusted to 800 rpm. The mixture was stirred and vacuumed for 2-4 h to mix the materials evenly, thereby obtaining component B.

[0351] (3) Preparation of polyurethane coating material:

[0352] The temperature of the reaction kettles 1 and 2 is adjusted to 80° C.-100° C., and the components A and B in the reaction kettles 1 and 2 are mixed at a mixing head so that the component A reacts with the component B to prepare a polyurethane coating material.

[0353] This embodiment also provides an application of a polyurethane coating material, which is used as a paint material for in-mold painting.

[0354] The temperature of reactors 1 and 2 was adjusted to 90°C, and the mold temperature was adjusted to 100°C. The A and B materials in reactors 1 and 2 were mixed at the mixing head through the injection molding equipment and then quickly injected into the mold system. After curing for a period of time, the mold was opened to obtain a coated part. The relevant parameters are shown in Table 8. Compared with Example 2, this comparative example only includes a hydroxyl-terminated hexamethylene diisocyanate trimer containing a dynamic disulfide bond, and does not include other modified triisocyanates containing repair bonds. The dynamic disulfide bond cannot form a synergistic effect with other repair bonds, and the gel time and curing time are longer. The repair time of scratches at 100°C is significantly increased, and the repair speed is slow.

[0355] Table 8 Sample parameters

[0356] Specification Gel time (s) Curing time (min) Scratch repair time at 100℃ (min) Comparative Example 3 200 45 420

[0357] Comparative Example 4

[0358] This comparative example provides a polyurethane coating material, a preparation method and an application thereof.

[0359] The polyurethane coating material is made of component A and component B in a mass ratio of 158.22:99.64, wherein:

[0360] Component A includes the following components expressed in parts by mass:

[0361] Highly active polyether polyol DEP-330G: 100 parts,

[0362] Bisphenol A epoxy resin (E-128): 15 parts,

[0363] Hydroxyl-terminated hexamethylene diisocyanate trimer containing dynamic disulfide bonds: 20.64 parts,

[0364] Amine-terminated hexamethylene diisocyanate trimer capable of forming multiple hydrogen bonds: 22.58 parts.

[0365] Component B includes the following components expressed in parts by mass:

[0366] Hexamethylene diisocyanate (HDI) trimer: 87.94 parts,

[0367] Defoaming agent (Z-5185): 2.6 parts,

[0368] Leveling agent( FL 3755): 2.6 parts,

[0369] Plasticizer (dibutyl phthalate): 2.6 parts,

[0370] Catalyst (m(triethylenediamine):m(dibutyltin dilaurate)=2:1)): 3.9 parts.

[0371] This embodiment also provides a method for preparing the polyurethane coating material, comprising the following steps:

[0372] (1) Preparation of component A

[0373] ① Preparation of hydroxyl-terminated hexamethylene diisocyanate trimer containing dynamic disulfide bonds:

[0374] n1 (small molecule -OH containing dynamic disulfide bond): n2 (HDI trimer -NCO) = 6:1.

[0375] In a three-necked flask, 15.1364 g of dihydroxyethyl disulfide (HEDS) was dissolved in 40 ml of N,N-dimethylacetamide solvent, and 5‰ of dibutyltin dilaurate catalyst was added based on the total mass of the system. The temperature was raised to 90°C, the stirring paddle speed was 1000 rpm, and 5.5016 g of hexamethylene diisocyanate (HDI) trimer (N3790) was slowly and accurately added dropwise to the three-necked flask within 6 hours through the "polymerization reaction drop control system". Stirring was continued for 4 hours. After removing the solvent, a hydroxyl-terminated HDI trimer containing dynamic disulfide bonds was obtained.

[0376] ② Preparation of amino-terminated hexamethylene diisocyanate trimer capable of forming multiple hydrogen bonds:

[0377] n7 (small molecule that can form multiple hydrogen bonds -NH2):n8 (HDI trimer -NCO) = 6:1.

[0378] In a three-necked flask, 17.0936 g of adipic acid dihydrazide was dissolved in 40 ml of N,N-dimethylacetamide solvent, and 5‰ of dibutyltin dilaurate catalyst was added based on the total mass of the system. The temperature was raised to 90°C, the stirring paddle speed was set at 1000 rpm, and 5.5016 g of hexamethylene diisocyanate (HDI) trimer (N3790) was slowly and accurately added dropwise to the three-necked flask over 6 hours via the "polymerization reaction drop control system". Stirring was continued for 4 hours. After removing the solvent, an amino-terminated HDI trimer capable of forming multiple hydrogen bonds was obtained.

[0379] ③ Add 20.64 g of hydroxyl-terminated HDI trimer containing dynamic disulfide bonds, 22.58 g of amine-terminated HDI trimer capable of forming multiple hydrogen bonds, 100 g of highly active polyether polyol DEP-330G, and 15 g of epoxy resin E-128 to reactor 1 in sequence, raise the temperature to 90°C, adjust the stirring blade speed to 800 rpm, stir and vacuum for 2 h to mix the raw materials evenly, cool and set aside to obtain component A.

[0380] (2) Preparation of component B

[0381] 87.94g HDI trimer, 2.6g Z-5185, 2.6g FL 3755, 2.6 g of dibutyl phthalate, and 3.9 g of catalyst were added to reactor 2. The stirring blade speed was adjusted to 800 rpm. The mixture was stirred and vacuumed for 2-4 h to mix the materials evenly, thereby obtaining component B.

[0382] (3) Preparation of polyurethane coating material:

[0383] The temperature of the reaction kettles 1 and 2 is adjusted to 80° C.-100° C., and the components A and B in the reaction kettles 1 and 2 are mixed at a mixing head so that the component A reacts with the component B to prepare a polyurethane coating material.

[0384] This embodiment also provides an application of a polyurethane coating material for in-mold painting. The temperatures of reactors 1 and 2 are adjusted to 90°C, and the mold temperature is adjusted to 100°C. Materials A and B from reactors 1 and 2 are mixed at the mixing head using injection molding equipment and then rapidly injected into the mold system. After a period of curing, the mold is opened to produce a coated part. The relevant parameters are shown in Table 9.

[0385] Compared with Example 2, this comparative example only includes a hydroxyl-terminated hexamethylene diisocyanate trimer containing a dynamic disulfide bond and an amino-terminated hexamethylene diisocyanate trimer capable of forming multiple hydrogen bonds, but does not include other modified triisocyanates containing repair bonds. The synergistic effect is poor, the gel time and curing time are long, the scratch repair time at 100°C is significantly increased, and the repair speed is slow.

[0386] Table 9 Sample parameters

[0387] Specification Gel time (s) Curing time (min) Scratch repair time at 100℃ (min) Comparative Example 4 160 30 350

[0388] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A polyurethane coating material, characterized in that: It is made of component A and component B in a mass ratio of (120-180): (30-120), wherein: In parts by mass, the component A comprises: Highly active polyether polyol: 90-110 parts, Hydroxyl-terminated triisocyanate containing a dynamic disulfide bond: 2 to 15 parts. The hydroxyl-terminated triisocyanate containing a dynamic disulfide bond is prepared by adding the materials at a ratio of n1:n2 = (5-7):1, where the amount of hydroxyl groups in the small molecule containing a dynamic disulfide bond n1 and the amount of isocyanate groups in the triisocyanate n2 are equal to; Amine-terminated triisocyanate containing a dynamic diselenide bond: 2 to 20 parts. The amine-terminated triisocyanate containing a dynamic diselenide bond is prepared by adding the materials at a ratio of n3 (the amount of amine group in the small molecule containing a dynamic diselenide bond) to n4 (the amount of isocyanate group in the triisocyanate) of (5-7):

1. Amine-terminated triisocyanate capable of forming multiple hydrogen bonds: 2 to 15 parts. The amine-terminated triisocyanate capable of forming multiple hydrogen bonds is prepared by adding the materials at a ratio of n7, the amount of the amine group in the small molecule capable of forming multiple hydrogen bonds, to n8, the amount of the isocyanate group in the triisocyanate, of (5-7):

1. In parts by mass, the B component includes: Triisocyanate: 0-100 parts, Diisocyanate: 0-60 parts.

2. The polyurethane coating material according to claim 1, characterized in that In parts by mass, the component A further comprises: Epoxy resin: 5-20 parts, Small molecules of diols: 0-30 parts, Hydroxyl-terminated triisocyanate containing dynamic carbon-carbon bonds: 2 to 21 parts; In terms of parts by mass, the B component also includes: Alkaline catalyst: 0.5 to 5 parts.

3. The polyurethane coating material according to claim 2, characterized in that In the A component: The hydroxyl-terminated triisocyanate containing a dynamic disulfide bond is prepared by reacting a diol small molecule containing a dynamic disulfide bond with triisocyanate; The amino-terminated triisocyanate containing a dynamic diselenide bond is prepared by reacting a diamine small molecule containing a dynamic diselenide bond with triisocyanate; The hydroxyl-terminated triisocyanate containing a dynamic carbon-carbon bond is prepared by reacting a diol small molecule containing a dynamic carbon-carbon bond with triisocyanate; The amino-terminated triisocyanate capable of forming multiple hydrogen bonds is prepared by reacting a diamine small molecule capable of forming multiple hydrogen bonds with triisocyanate.

4. The polyurethane coating material according to claim 3, characterized in that The diol small molecule containing a dynamic disulfide bond is selected from at least one of dihydroxyethyl disulfide and dihydroxydiphenyl disulfide; The diamine small molecule containing a dynamic diselenide bond is bis(2-aminophenyl) diselenide; The diol small molecule containing a dynamic carbon-carbon bond is 1,2-bis(4-(2-hydroxyethoxy)phenyl)-1,2-diphenylethane-1,2-diol; The diamine small molecule capable of forming multiple hydrogen bonds is adipic acid dihydrazide.

5. The polyurethane coating material according to claim 1, characterized in that The triisocyanate is selected from any one or more of hexamethylene diisocyanate trimer and L-lysine triisocyanate. The diisocyanate is selected from one or more of hexamethylene diisocyanate, toluene diisocyanate, isophorone diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate.

6. The polyurethane coating material according to claim 2, characterized in that: In the A component: The highly active polyether polyol is selected from any one or more of polyether polyol DEP-330G and polyether polyol DEP-3600H; The epoxy resin is selected from any one or more of bisphenol A epoxy resin E-51 and bisphenol A epoxy resin E-128; The diol small molecule is selected from any one or more of ethylene glycol, diethylene glycol, 1,4-butanediol, and 1,6-hexanediol.

7. The polyurethane coating material according to claim 1, characterized in that In the component B, the mass fraction of triisocyanate is 10 to 90 parts, and the mass fraction of diisocyanate is 10 to 50 parts.

8. A method for preparing a polyurethane coating material, characterized in that: The steps include: Step 1: Preparation of component A: Mix highly active polyether polyol, hydroxyl-terminated triisocyanate containing dynamic disulfide bonds, amine-terminated triisocyanate containing dynamic diselenide bonds, and amine-terminated triisocyanate capable of forming multiple hydrogen bonds at a temperature of 80-100°C under vacuum conditions; Preparation of the hydroxyl-terminated triisocyanate containing dynamic disulfide bonds: The ratio of the amount of hydroxyl groups in the small molecule containing dynamic disulfide bonds, n1:n2, to the amount of isocyanate groups in the triisocyanate, n2, is (5-7):

1. The materials are added; the preparation of the amino-terminated triisocyanate containing a dynamic diselenide bond: the materials are added at a ratio of n3:n4 = (5-7):1 of the amount of the amino group substance n3 in the small molecule containing a dynamic diselenide bond to the amount of the isocyanate group substance n4 in the triisocyanate; the preparation of the amino-terminated triisocyanate capable of forming multiple hydrogen bonds: the materials are added at a ratio of n7:n8 = (5-7):1 of the amount of the amino group substance n7 in the small molecule capable of forming multiple hydrogen bonds to the amount of the isocyanate group substance n8 in the triisocyanate; Step 2: Preparation of component B: Mix triisocyanate and diisocyanate evenly; Step 3: Preparation of polyurethane coating material: Component A and component B are mixed at a mass ratio of (120-180): (30-120) at a temperature of 80-100° C., and the component A and the component B react to obtain the polyurethane coating material.

9. The preparation method according to claim 8, characterized in that During the preparation of the A component, diol small molecules, epoxy resin, and hydroxyl-terminated triisocyanate containing dynamic carbon-carbon bonds are also added; During the preparation of the B component, an alkaline catalyst and an auxiliary agent are also added. The auxiliary agent is one or more of a defoaming agent, a leveling agent, and a plasticizer.

10. Use of the polyurethane coating material according to any one of claims 1 to 7 or the polyurethane coating material obtained by the preparation method according to any one of claims 8 to 9, characterized in that: The polyurethane coating material is used for in-mold painting.

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