Water-based two-component polyurethane primer as well as preparation method and application thereof

Abstract

The invention discloses a water-based two-component polyurethane primer as well as a preparation method and application thereof, and belongs to the technical field of coating compositions. The water-based two-component polyurethane primer provided by the invention comprises a component A and a component B. The component A comprises water-based hydroxy acrylic resin; conductive carbon black; a coalescing agent; a thickening agent; a wetting agent; a defoaming agent; a wetting dispersant; a pH adjusting agent; water; the component B comprises a solvent type isocyanate curing agent; a solvent; the water-based hydroxyl acrylic resin is selected from water-based hydroxyl acrylic resin containing epoxy groups. Epoxy groups are introduced into the water-based hydroxyl acrylic resin, so that the obtained primer has good adhesive force on different substrates, and can be used for multiple purposes; and a solvent type curing agent can be used for curing, so that the cost is reduced, the service life is longer, the curing performance is better, and the production requirements can be met under the condition that the existing coating process is not changed.

Description

Technical Field

[0001] The invention belongs to the technical field of coating compositions, and in particular relates to a water-based two-component polyurethane primer and a preparation method and application thereof. Background Art

[0002] When coating on plastic substrates, due to its low surface tension, it is easy to cause poor wetting of the coating on the surface; in addition, since the substrate needs to be made into different shapes to meet various practical needs, edges and gaps may appear, and problems such as uneven coating and sagging are also prone to occur during the coating process. Solvent-based coatings can adjust the actual coating line through factors such as the solubility of different solvents, the size of surface tension, and the speed of evaporation. Water-based coatings use water as a solvent and cannot be adjusted in the above measures, so various construction problems are more likely to occur, resulting in a decrease in product yield. In addition, due to the structural differences between acrylonitrile-butadiene-styrene copolymer (ABS), polycarbonate (PC) and fiberglass, two different primers are currently used to solve the adhesion problem, affecting daily production. However, according to green environmental protection requirements, traditional solvent-based coatings are no longer suitable for market demand, and water-based coatings are imperative.

[0003] As a safety protective equipment for the head, the surface coating of the helmet can not only beautify it, but also enhance its water resistance, wear resistance, collision resistance, corrosion resistance and other properties, effectively improving the service life and safety of the helmet. Rotary disc electrostatic coating is widely used in the coating of helmets due to its high efficiency and ease of use. However, most helmets are made of plastics such as ABS, PC, and fiberglass as the main materials. Their low surface tension and the characteristics of rotary disc electrostatic coating can easily cause poor wetting of the paint on the surface, resulting in pinholes, shrinkage holes, poor leveling and even poor adhesion. In addition, since the surface of the helmet is a spherical surface with many edges, corners and gaps, it is easy to have problems with oil accumulation and sagging during the coating process. Summary of the invention

[0004] In order to overcome at least one of the problems existing in the above-mentioned prior art, one of the objects of the present invention is to provide a water-based two-component polyurethane primer having excellent water dispersibility, good wettability, good leveling property and excellent anti-sagging property.

[0005] A second object of the present invention is to provide a method for preparing the above-mentioned water-based two-component polyurethane primer.

[0006] A third object of the present invention is to provide an application of the above-mentioned water-based two-component polyurethane primer.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] The first aspect of the present invention provides a water-based two-component polyurethane primer, comprising a component A and a component B, wherein the component A comprises the following components in parts by weight:

[0009]

[0010] The B component includes the following components in parts by weight:

[0011] 70-80 parts of solvent-based isocyanate curing agent;

[0012] 20-30 parts of solvent;

[0013] The waterborne hydroxyl acrylic resin is selected from waterborne hydroxyl acrylic resins containing epoxy groups.

[0014] The present invention introduces epoxy groups into the water-based hydroxy acrylic resin, so that the primer obtained has good adhesion on different substrates, and can achieve multiple uses of one paint; and can be cured using a solvent-based curing agent, which reduces costs while extending the service life and improving the curing performance, and can meet production needs without changing the existing coating process.

[0015] Preferably, the A component comprises the following components in parts by weight:

[0016]

[0017] Preferably, the B component includes the following components in parts by weight:

[0018] 70-75 parts of solvent-based isocyanate curing agent;

[0019] 25 to 30 parts of solvent.

[0020] Preferably, the mass ratio of the component A to the component B is 100:(5-30); more preferably, it is 100:(10-20); and even more preferably, it is 100:(10-15).

[0021] Preferably, the epoxy group content in the epoxy group-containing waterborne hydroxyl acrylic resin is 5 to 10 wt %, and more preferably 7 to 9 wt %.

[0022] Preferably, in the A component, the conductive carbon black is selected from VXC72R.

[0023] Preferably, in the component A, the film-forming aid includes a first film-forming aid and a second film-forming aid; the first film-forming aid includes at least one of dipropylene glycol methyl ether, propylene glycol methyl ether, diethylene glycol methyl ether or ethylene glycol methyl ether; the second film-forming aid includes at least one of dipropylene glycol butyl ether, alcohol ester dodeca, ethylene glycol butyl ether or propylene glycol butyl ether; further preferably, the first film-forming aid includes dipropylene glycol methyl ether, propylene glycol methyl ether or a combination thereof; the second film-forming aid includes dipropylene glycol butyl ether, alcohol ester dodeca or a combination thereof; further preferably, the first film-forming aid is selected from dipropylene glycol methyl ether; the second film-forming aid is selected from dipropylene glycol butyl ether.

[0024] Preferably, the mass ratio of the first film-forming aid to the second film-forming aid is 1:(0.1-5); more preferably 1:(0.5-3); and even more preferably 1:(0.8-2).

[0025] Preferably, in the component A, the thickener includes a first thickener and a second thickener; the first thickener is selected from a polyurethane thickener; the second thickener is selected from a polyether polyurethane thickener; further preferably, the first thickener is selected from Coapur XS83; the second thickener is selected from Rheolate299.

[0026] Preferably, the mass ratio of the first thickener to the second thickener is 1:(0.1-5); more preferably 1:(0.5-3); and even more preferably 1:(0.8-2).

[0027] Preferably, in component A, the wetting agent includes a first wetting agent and a second wetting agent; the first wetting agent is selected from gemini silicone wetting agents; the second wetting agent is selected from modified silicone wetting agents; further preferably, the first wetting agent includes TEGO4000, TEGO4100 or a combination thereof; the second wetting agent includes FLOW487U, FLOW488 or a combination thereof; further preferably, the first wetting agent is selected from TEGO4000; the second wetting agent is selected from FLOW487U.

[0028] Preferably, the mass ratio of the first wetting agent to the second wetting agent is 1:(0.1-5); more preferably, it is 1:(0.5-3); and even more preferably, it is 1:(0.8-2).

[0029] Preferably, in the component A, the defoamer is selected from a polyether siloxane copolymer defoamer containing fumed silica; further preferably, the defoamer includes a first defoamer and a second defoamer; the first defoamer is selected from TEGO Foamex 810; the second defoamer includes TEGO AIREX 901W, TEGO AIREX 902W or a combination thereof; further preferably, the first defoamer is selected from TEGO Foamex 810; the second defoamer is selected from TEGO AIREX 901W.

[0030] Preferably, the mass ratio of the first defoaming agent to the second defoaming agent is 1:(0.1-5); more preferably, it is 1:(0.5-3); and even more preferably, it is 1:(0.8-2).

[0031] Preferably, in the component A, the wetting and dispersing agent is selected from copolymer wetting and dispersing agents containing pigment affinity groups; further preferably, the wetting and dispersing agent includes BYK2012, BYK190 or a combination thereof; further preferably, the wetting and dispersing agent is selected from BYK2012.

[0032] Preferably, in the component A, the pH adjuster includes at least one of monoethanolamine, diethanolamine, triethanolamine or ammonia water; more preferably, the pH adjuster is selected from diethanolamine.

[0033] Preferably, the pH value of the A component is 7-11; more preferably 7.5-10.5; further preferably 8-10.

[0034] Preferably, in the B component, the solvent-based isocyanate curing agent includes at least one of a hexamethylene diisocyanate curing agent, a diphenylmethane diisocyanate curing agent or a toluene diisocyanate curing agent; further preferably, the solvent-based isocyanate curing agent is selected from a hexamethylene diisocyanate curing agent; further preferably, the solvent-based isocyanate curing agent is selected from TPA100.

[0035] Preferably, in the B component, the solvent includes at least one of propylene glycol methyl ether acetate, propylene glycol diacetate, ethyl acetate, butyl acetate, cyclohexanone or xylene; further preferably, the solvent includes at least one of propylene glycol methyl ether acetate, propylene glycol diacetate or ethyl acetate; further preferably, the solvent is selected from propylene glycol methyl ether acetate.

[0036] The second aspect of the present invention provides a method for preparing the waterborne two-component polyurethane primer according to the first aspect of the present invention, comprising the following steps:

[0037] S1, mixing conductive carbon black, a wetting dispersant, a part of a defoamer and a part of water to obtain a carbon black slurry; mixing an aqueous hydroxy acrylic resin, a film-forming aid, a thickener, a wetting agent, a pH adjuster, the remaining defoamer and the remaining water to obtain a resin dispersion; adding the carbon black slurry to the resin dispersion to obtain component A;

[0038] S2, mixing a solvent-based isocyanate curing agent and a solvent to obtain component B;

[0039] S3, mixing the component A and the component B to obtain the water-based two-component polyurethane primer.

[0040] Preferably, in step S1, the conductive carbon black, the wetting and dispersing agent, part of the defoaming agent and part of the water are mixed and then ground; further preferably, the carbon black slurry is ground until the fineness is less than 20 microns.

[0041] The third aspect of the present invention provides a use of the water-based two-component polyurethane primer described in the first aspect of the present invention in coating of plastic substrates.

[0042] Preferably, the material of the plastic substrate includes at least one of acrylonitrile-butadiene-styrene copolymer (ABS), polycarbonate (PC) or fiberglass; further preferably, the material of the plastic substrate includes acrylonitrile-butadiene-styrene copolymer (ABS), polycarbonate (PC) and fiberglass.

[0043] Preferably, the plastic substrate is a helmet.

[0044] Preferably, the coating method is electrostatic coating; further preferably, the coating method is rotary disc electrostatic coating.

[0045] The beneficial effects of the present invention are as follows: the water-based two-component polyurethane primer of the present invention can help the coating wet the substrate, overcome the adverse effects on construction caused by the low surface tension of the substrate and the coating equipment, and take into account leveling and anti-sagging; by introducing epoxy groups into the main resin, the adhesion on various substrates is effectively improved, so that one paint can be used for multiple purposes, production efficiency is improved, and waste is reduced; in combination with a solvent-based isocyanate curing agent, the service life is extended, the overall formulation cost is reduced, and the same level as solvent-based coatings is achieved.

[0046] Specifically, compared with the prior art, this application has the following advantages:

[0047] 1. The water-based two-component polyurethane primer of the present invention uses a water-based hydroxyl acrylic resin containing a small amount of epoxy groups and an isocyanate curing agent for cross-linking reaction, and at the same time, by adding suitable conductive carbon black, wetting agent, film-forming aid, thickener and other raw materials, the obtained polyurethane primer can take into account wetting, leveling and anti-sagging during rotary disk electrostatic coating, showing excellent appearance effect.

[0048] 2. The wetting agent, film-forming aid and thickener of the present invention are reasonably composed with other components and matched with a solvent-based isocyanate curing agent, so that the water-based polyurethane primer can achieve the same appearance and performance as solvent-based coatings with low VOC. At the same time, due to the introduction of a small amount of epoxy groups in the resin, the coating has excellent adhesion not only on ABS and PC, but also on glass fiber reinforced plastic substrates.

[0049] 3. The present invention can overcome the adverse effects of substrates and equipment, solve various problems in the coating process, provide a more excellent appearance, improve product yield, and improve production efficiency without changing the coating process and ensuring the mechanical and weather resistance of the coating. In addition, solvent-based curing agents can be used, with a longer activation period and lower costs. The water-based two-component polyurethane primer provided by the present invention has good application prospects in plastic substrate coating. DETAILED DESCRIPTION

[0050] The content of the present invention is further described in detail below through specific examples. It should also be understood that the following examples are only used to further illustrate the present invention and cannot be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the principles set forth in the present invention all belong to the scope of protection of the present invention. The specific process parameters and the like in the following examples are also only examples within a suitable range, that is, those skilled in the art can make a selection within a suitable range through the description herein, and are not limited to the specific data exemplified below. The raw materials, reagents or devices used in the following examples and comparative examples, unless otherwise specified, can all be obtained from conventional commercial sources, or can be obtained by existing known methods.

[0051] It should be noted that some of the raw material information used in the following examples and comparative examples of the present invention is as follows:

[0052] The water-based hydroxyl acrylic resin containing epoxy groups is a water-based hydroxyl acrylic resin containing 8 wt% epoxy groups; the solvent-based isocyanate curing agent TPA100 was purchased from Asahi Chemical Corporation; VXR72 conductive carbon black was purchased from Cabot Corporation; CoapurXS83 was purchased from Arkema; ​​Rheolate299 was purchased from Hemmings; TEGO4000 and TEGO4100, TEGOFoamex810, TEGO AIREX901W and AIREX902W were purchased from Evonik; FLOW487U and FLOW488 were purchased from UCAR; BYK2012 and BYK190 were purchased from BYK.

[0053] In the following examples and comparative examples of the present invention, the parts are by mass.

[0054] Example 1

[0055] A water-based two-component polyurethane primer, the specific preparation steps are as follows:

[0056] S1. Grind 3.5 parts of VXR72 conductive carbon black with 2.5 parts of BYK2012, 0.4 parts of Foamex810 and 7 parts of deionized water to a fineness of less than 20 microns to prepare carbon black slurry for standby use. Weigh 50 parts of water-based hydroxyl acrylic resin containing epoxy groups, 30 parts of deionized water, 1 part of TEGO4000, 1 part of FLOW487U, 0.5 parts of AIREX901W, 1 part of Coapur XS83, 1 part of Rheolate299, 0.3 parts of diethanolamine, 5 parts of dipropylene glycol methyl ether, and 5 parts of dipropylene glycol butyl ether, stir evenly, and then add the ground carbon black slurry to the above mixed solution to prepare component A; the pH value of component A is 8-10;

[0057] S2, weigh 70 parts of isocyanate curing agent TPA100 and 30 parts of dipropylene glycol methyl ether acetate, stir evenly to obtain component B;

[0058] S3. Mix 100 parts of component A and 12 parts of component B to prepare a water-based two-component polyurethane primer.

[0059] Example 2

[0060] A water-based two-component polyurethane primer, the specific preparation steps are as follows:

[0061] S1. Grind 4 parts of VXR72 conductive carbon black with 3 parts of BYK2012, 0.5 parts of Foamex810 and 8 parts of deionized water to a fineness of less than 20 microns, and set aside. Weigh 45 parts of water-based hydroxyl acrylic resin containing epoxy groups, 35 parts of deionized water, 0.8 parts of TEGO4100, 0.8 parts of FLOW488U, 0.5 parts of AIREX902W, 0.8 parts of Coapur XS83, 0.8 parts of Rheolate299, 0.3 parts of diethanolamine, 4 parts of dipropylene glycol methyl ether, 4 parts of dipropylene glycol butyl ether, stir evenly, and then add the ground carbon black slurry to the above mixed solution to obtain component A; the pH value of component A is 8-10;

[0062] S2, weigh 75 parts of isocyanate curing agent TPA100 and 25 parts of dipropylene glycol methyl ether acetate, stir evenly to prepare component B;

[0063] S3. Mix 100 parts of component A and 10 parts of component B to prepare a water-based two-component polyurethane primer.

[0064] Example 3

[0065] A water-based two-component polyurethane primer, the difference between this example and Example 1 is that:

[0066] The film-forming aid dipropylene glycol methyl ether in Example 1 was replaced with propylene glycol methyl ether, and the remaining raw materials and preparation method were the same as in Example 1.

[0067] Example 4

[0068] A water-based two-component polyurethane primer, the difference between this example and Example 1 is that:

[0069] The film-forming aid dipropylene glycol butyl ether in Example 1 was replaced with alcohol ester twelve, and the remaining raw materials and preparation method were the same as in Example 1.

[0070] Example 5

[0071] A water-based two-component polyurethane primer, the difference between this example and Example 1 is that:

[0072] The Rheolate 299 in Example 2 was removed, and the remaining raw materials and preparation method were the same as in Example 2.

[0073] Example 6

[0074] A water-based two-component polyurethane primer, the difference between this example and Example 1 is that:

[0075] The Coapur XS83 in Example 1 was removed, and the remaining raw materials and preparation method were the same as in Example 1.

[0076] Example 7

[0077] A water-based two-component polyurethane primer, the difference between this example and Example 1 is that:

[0078] The TEGO4000 in Example 1 was removed, and the remaining raw materials and preparation method were the same as in Example 1.

[0079] Example 8

[0080] A water-based two-component polyurethane primer, the difference between this example and Example 1 is that:

[0081] The FLOW488U in Example 2 was removed, and the remaining raw materials and preparation method were the same as in Example 1.

[0082] Comparative Example 1

[0083] A water-based two-component polyurethane primer, the difference between this example and Example 1 is that:

[0084] The conductive carbon black VXR72 in Example 1 was replaced with ordinary carbon black, and the remaining raw materials and preparation method were the same as in Example 1.

[0085] Comparative Example 2

[0086] A water-based two-component polyurethane primer, the difference between this example and Example 1 is that:

[0087] The TPA100 curing agent in Example 1 was replaced with Covestro 2655 water-based curing agent in an amount of 14 parts.

[0088] Comparative Example 3

[0089] A water-based two-component polyurethane primer, the difference between this example and Example 1 is that:

[0090] The TPA100 curing agent in Example 1 was replaced with DIC DNW5500 water-based curing agent in an amount of 18 parts.

[0091] Comparative Example 4

[0092] A water-based two-component polyurethane primer, the difference between this example and Example 1 is that:

[0093] The water-based hydroxylated acrylic resin containing epoxy groups in Example 1 was replaced with a common hydroxylated acrylic resin not containing epoxy groups.

[0094] Comparative Example 5

[0095] A water-based two-component polyurethane primer, the difference between this example and Example 1 is that:

[0096] The water-based hydroxy acrylic resin containing epoxy groups in Example 1 is replaced by epoxy resin, and the curing agent is replaced by polyamide curing agent, and the proportions are calculated based on equivalents.

[0097] Performance Testing

[0098] The water-based two-component polyurethane primers obtained in Examples 1 to 8 and Comparative Examples 1 to 5 were adjusted to a construction viscosity of Iwata 2# cup for 30 seconds, and then subjected to a rotary disc electrostatic coating on a helmet production line to test the coating effect. The specific results are shown in Table 1. Among them, the adhesion was tested in accordance with GB / T 9286-2021; the hardness was the pencil hardness; the wettability, leveling, and anti-sagging properties were obtained by visual inspection.

[0099] Table 1 Coating effect of water-based two-component polyurethane primer obtained in Examples 1 to 8 and Comparative Examples 1 to 5

[0100]

[0101] As can be seen from Table 1, the polyurethane primers of Examples 1 to 8 are significantly better than the polyurethane primers obtained in Comparative Examples 1 to 5 in terms of comprehensive adhesion, atomization effect, wettability, leveling and anti-sagging. Since Comparative Example 1 does not add conductive carbon black but uses ordinary carbon black, the adhesion, atomization effect, wettability and leveling of the paint are relatively poor. Since solvent-based curing agents can be used, Examples 1 to 2 are significantly better than the water-based curing agents used in Comparative Examples 2 to 3 in terms of activation period and cost. Comparative Example 4 uses ordinary hydroxyl acrylic resin that does not contain epoxy groups. Although it has a grade 0 adhesion on ABS and PC, it has poor adhesion on glass fiber reinforced plastics. Comparative Example 5 uses epoxy resin. Although it has a qualified adhesion on glass fiber reinforced plastics, it cannot have adhesion on plastics such as ABS and PC. Therefore, the two resins used in Comparative Examples 4 to 5 cannot be used universally on various plastic substrates, and more than two different primers need to be used to solve the adhesion problem, which affects daily production.

[0102] Among Examples 1 to 8, the polyurethane primer of Examples 1 to 2 is worse than the polyurethane primer obtained in Examples 3 to 8; the film-forming aid used in Examples 3 to 4 is not as good as that in Examples 1 to 2, resulting in decreased wettability, leveling and anti-sagging properties; Examples 5 to 6 only use one thickener, and its thickening effect is not as good as that in Examples 1 to 2, resulting in significantly poor anti-sagging properties; Examples 7 to 8 only use one wetting agent, and its wetting effect is not as good as that in Examples 1 to 2, resulting in decreased wettability and leveling properties.

[0103] The waterborne two-component polyurethane primer in the embodiment of the present invention uses a waterborne hydroxyl acrylic resin containing a small amount of epoxy groups and a solvent-based isocyanate curing agent for cross-linking reaction. At the same time, by adding suitable conductive carbon black, wetting agent, film-forming aid, thickener and other raw materials, the obtained polyurethane primer can take into account both wetting and leveling and anti-sagging during rotary plate electrostatic coating, showing excellent appearance effects. And because the components such as wetting agent, film-forming aid and thickener in the embodiment of the present invention are reasonably composed, they can be matched with solvent-based isocyanate curing agent, so that the obtained waterborne polyurethane primer has the same appearance and performance as solvent-based coatings while having low VOC. At the same time, due to the introduction of a small amount of epoxy groups in the resin, the coating not only has excellent adhesion on ABS and PC, but also has excellent adhesion on glass fiber reinforced plastic substrates.

[0104] The embodiments of the present invention can overcome the adverse effects of substrates and equipment, solve various problems in the coating process, provide a more excellent appearance, improve product yield, and improve production efficiency without changing the coating process and ensuring the mechanical and weather resistance of the coating. In addition, solvent-based curing agents can be used, with a longer activation period and lower costs. The water-based two-component polyurethane primer provided by the embodiments of the present invention has good application prospects in plastic substrate coating.

[0105] In summary, the water-based two-component polyurethane primer of the present invention can help the coating wet the substrate, overcome the adverse effects of the low surface tension of the substrate and the coating equipment on the construction, take into account leveling and anti-sagging, and effectively improve the adhesion on various substrates by introducing epoxy groups into the main resin, so as to achieve multiple uses of one paint, improve production efficiency and reduce waste; when used with a solvent-based isocyanate curing agent, the service life is extended, the overall formulation cost is reduced, and the level is the same as that of solvent-based coatings.

Claims

1. A water-based two-component polyurethane primer, characterized in that: It comprises component A and component B, wherein the component A comprises the following components in parts by weight: The B component includes the following components in parts by weight: 70-80 parts of solvent-based isocyanate curing agent; 20-30 parts of solvent; The waterborne hydroxyl acrylic resin is selected from waterborne hydroxyl acrylic resins containing epoxy groups.

2. The water-based two-component polyurethane primer according to claim 1, characterized in that: The mass ratio of the A component to the B component is 100:(5-20).

3. The water-based two-component polyurethane primer according to claim 1, characterized in that: The epoxy group content in the epoxy group-containing waterborne hydroxyl acrylic resin is 5 to 10 wt %.

4. The water-based two-component polyurethane primer according to claim 1, characterized in that: In the component A, the film-forming aid includes a first film-forming aid and a second film-forming aid; the first film-forming aid includes at least one of dipropylene glycol methyl ether, propylene glycol methyl ether, diethylene glycol methyl ether or ethylene glycol methyl ether; the second film-forming aid includes at least one of dipropylene glycol butyl ether, alcohol ester dodecahydrate, ethylene glycol butyl ether or propylene glycol butyl ether.

5. The water-based two-component polyurethane primer according to claim 1, characterized in that: In the component A, the thickener includes a first thickener and a second thickener; the first thickener is selected from polyurethane thickeners; and the second thickener is selected from polyether polyurethane thickeners.

6. The water-based two-component polyurethane primer according to claim 1, characterized in that: In the component A, the wetting agent includes a first wetting agent and a second wetting agent; the first wetting agent is selected from gemini-type silicone wetting agents; and the second wetting agent is selected from modified silicone wetting agents.

7. The water-based two-component polyurethane primer according to claim 1, characterized in that: In the component A, the defoamer is selected from polyether siloxane copolymer defoamers containing fumed silica; And / or, in the component A, the wetting and dispersing agent is selected from copolymer wetting and dispersing agents containing pigment affinity groups; And / or, in the component A, the pH adjuster comprises at least one of monoethanolamine, diethanolamine, triethanolamine or ammonia water; And / or, the pH value of the A component is 7-11.

8. The water-based two-component polyurethane primer according to claim 1, characterized in that: In the B component, the solvent-based isocyanate curing agent includes at least one of a hexamethylene diisocyanate curing agent, a diphenylmethane diisocyanate curing agent or a toluene diisocyanate curing agent; And / or, in the component B, the solvent includes at least one of propylene glycol methyl ether acetate, propylene glycol diacetate, ethyl acetate, butyl acetate, cyclohexanone or xylene.

9. A method for preparing a waterborne two-component polyurethane primer as claimed in any one of claims 1 to 8, characterized in that: The following steps are involved: S1, mixing conductive carbon black, a wetting dispersant, a part of a defoamer and a part of water to obtain a carbon black slurry; mixing an aqueous hydroxy acrylic resin, a film-forming aid, a thickener, a wetting agent, a pH adjuster, the remaining defoamer and the remaining water to obtain a resin dispersion; adding the carbon black slurry to the resin dispersion to obtain component A; S2, mixing a solvent-based isocyanate curing agent and a solvent to obtain component B; S3, mixing the component A and the component B to obtain the water-based two-component polyurethane primer.

10. Use of the water-based two-component polyurethane primer according to any one of claims 1 to 8 in coating a plastic substrate; preferably, the material of the plastic substrate comprises at least one of acrylonitrile-butadiene-styrene copolymer, polycarbonate or fiberglass.

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