A waterborne two-component polyurethane primer, its preparation method and application

Abstract

The application discloses a kind of water-based two-component polyurethane primer and its preparation method and application, belong to coating composition technical field.The water-based two-component polyurethane primer provided by the application includes component A and component B, wherein the component A includes: water-based hydroxyl acrylic resin;Conductive carbon black;Film forming aid;Thickening agent;Wetting agent;Defoaming agent;Wetting dispersing agent;pH adjusting agent;Water;The component B includes: solvent type isocyanate curing agent;Solvent;The water-based hydroxyl acrylic resin is selected from water-based hydroxyl acrylic resin containing epoxy group.The primer obtained by introducing epoxy group in water-based hydroxyl acrylic resin has good adhesion on different substrates, and one paint can be used for multiple purposes;And solvent type curing agent can be used for curing, reduce cost while longer service life, better curing performance, can meet production demand without changing existing coating process.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coating compositions, and particularly relates to a water-based two-component polyurethane primer as well as a preparation method and application thereof. BACKGROUND

[0002] When coating is performed on a plastic substrate, due to the characteristics of low surface tension, it is easy to cause the phenomenon that the coating is poorly wetted on the surface. In addition, due to the fact that the substrate needs to be made into different shapes to adapt to various actual needs, corners and gaps may occur, and uneven coating, sagging and other problems are also easy to occur in the coating process. Solvent-based coatings can be adjusted by different solvents according to the strength of the solubility, the size of the surface tension, the speed of the evaporation rate and other factors. However, water-based coatings use water as the solvent and cannot be adjusted in the above-mentioned aspects, so various construction problems are more likely to occur, resulting in a decrease in product yield. Moreover, due to the structural differences of acrylonitrile-butadiene-styrene copolymer (ABS), polycarbonate (PC) and glass steel, two different primers are currently used to solve the adhesion problem, which affects daily production. However, according to the green environmental protection requirements, the traditional solvent-based coatings have not adapted to the market demand, and water-based coatings are imperative.

[0003] As a safety protection product for protecting the head, the coating treatment on the surface of the helmet not only has a beautifying effect, but also can enhance the water resistance, wear resistance, impact resistance, corrosion resistance and other properties of the helmet, effectively improving the service life and safety of the helmet. The rotary disc electrostatic coating is widely used in the coating of helmets due to its high efficiency and convenience. However, most helmets are made of plastic materials such as ABS, PC and glass steel, and the low surface tension combined with the characteristics of the rotary disc electrostatic coating can easily cause the coating to be poorly wetted on the surface, resulting in phenomena such as pinholes, shrinkage, poor leveling and even poor adhesion. In addition, the surface of the helmet is a spherical surface, and there are many corners and gaps, so the problem of oil accumulation and sagging is also easy to occur in the coating process. SUMMARY

[0004] In order to overcome at least one problem existing in the prior art, one of the purposes of the present application is to provide a water-based two-component polyurethane primer which has excellent water dispersibility, good wetting property, good leveling property and excellent anti-sagging property.

[0005] The second purpose of the present application is to provide a preparation method of the above-mentioned water-based two-component polyurethane primer.

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

[0007] In order to achieve the above-mentioned purposes, the technical solution adopted by the present application is as follows:

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

[0009]

[0010] The component B comprises the following components by mass fraction:

[0011] a solvent type isocyanate curing agent 70-80 parts;

[0012] a solvent 20-30 parts;

[0013] The water-based hydroxyl acrylic resin is selected from water-based hydroxyl acrylic resins containing epoxy groups.

[0014] The present application introduces epoxy groups into the water-based hydroxyl acrylic resin, and the obtained primer has good adhesion on different substrates, can realize one paint multiple use, and can use a solvent type curing agent for curing, thereby reducing the cost, prolonging the service life, and having better curing performance, and can meet the production requirements without changing the existing coating process.

[0015] Preferably, the component A comprises the following components by mass fraction:

[0016]

[0017] Preferably, the component B comprises the following components by mass fraction:

[0018] a solvent type isocyanate curing agent 70-75 parts;

[0019] a solvent 25-30 parts.

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

[0021] Preferably, the content of the epoxy groups in the water-based hydroxyl acrylic resin containing epoxy groups is 5-10 wt%; and further preferably 7-9 wt%.

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

[0023] Preferably, in the A component, the film forming aid comprises a first film forming aid and a second film forming aid; the first film forming aid comprises 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 comprises at least one of dipropylene glycol butyl ether, OLETH-12, ethylene glycol butyl ether or propylene glycol butyl ether; further preferably, the first film forming aid comprises dipropylene glycol methyl ether, propylene glycol methyl ether or a combination thereof; the second film forming aid comprises dipropylene glycol butyl ether, OLETH-12 or a combination thereof; still 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 and the second film forming aid is 1:(0.1-5); further preferably 1:(0.5-3); still further preferably 1:(0.8-2).

[0025] Preferably, in the A component, the thickening agent comprises a first thickening agent and a second thickening agent; the first thickening agent is selected from polyurethane thickening agent; the second thickening agent is selected from polyether polyurethane thickening agent; further preferably, the first thickening agent is selected from Coapur XS83; the second thickening agent is selected from Rheolate 299.

[0026] Preferably, the mass ratio of the first thickening agent and the second thickening agent is 1:(0.1-5); further preferably 1:(0.5-3); still further preferably 1:(0.8-2).

[0027] Preferably, in the A component, the wetting agent comprises a first wetting agent and a second wetting agent; the first wetting agent is selected from Gemini silicone wetting agent; the second wetting agent is selected from modified silicone wetting agent; further preferably, the first wetting agent comprises TEGO 4000, TEGO 4100 or a combination thereof; the second wetting agent comprises FLOW 487U, FLOW 488 or a combination thereof; still further preferably, the first wetting agent is selected from TEGO 4000; the second wetting agent is selected from FLOW 487U.

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

[0029] Preferably, in the A component, the defoaming agent is selected from the group consisting of polyether siloxane copolymer defoaming agents containing fumed silica; further preferably, the defoaming agent comprises a first defoaming agent and a second defoaming agent; the first defoaming agent is selected from TEGO Foamex 810; the second defoaming agent comprises TEGO AIREX 901W, TEGO AIREX 902W or a combination thereof; more preferably, the first defoaming agent is selected from TEGO Foamex 810; the second defoaming agent is selected from TEGO AIREX 901W.

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

[0031] Preferably, in the A component, the wet dispersant is selected from the group consisting of copolymer wet dispersants containing pigment affinity groups; further preferably, the wet dispersant comprises BYK 2012, BYK 190 or a combination thereof; more preferably, the wet dispersant is selected from BYK 2012.

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

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

[0034] Preferably, in the B component, the solvent type isocyanate curing agent comprises at least one of hexamethylene diisocyanate curing agent, diphenylmethane diisocyanate curing agent or toluene diisocyanate curing agent; further preferably, the solvent type isocyanate curing agent is selected from hexamethylene diisocyanate curing agent; more preferably, the solvent type isocyanate curing agent is selected from TPA 100.

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

[0036] The second aspect of the present application provides a preparation method of the water-based two-component polyurethane primer of the first aspect of the present application, comprising the following steps:

[0037] S1, mixing the conductive carbon black, wetting dispersant, part of the defoaming agent and part of the water to obtain a carbon black slurry; mixing the water-based hydroxyl acrylic resin, film forming aid, thickening agent, wetting agent, pH regulator, the rest of the defoaming agent and the rest of the water to obtain a resin dispersion; adding the carbon black slurry in the resin dispersion to obtain component A;

[0038] S2, mixing the solvent type isocyanate curing agent and 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 the step S1, after mixing the conductive carbon black, wetting dispersant, part of the defoaming agent and part of the water, grinding is further performed; further preferably, the grinding is performed to a fineness of less than 20 microns of the carbon black slurry.

[0041] The third aspect of the present application provides an application of the water-based two-component polyurethane primer of the first aspect of the present application in plastic substrate coating.

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

[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 water-based two-component polyurethane primer of the present application can help the paint to wet the substrate, overcome the adverse effects on construction caused by the low surface tension of the substrate and the coating equipment, and balance the leveling and anti-sagging; by connecting the epoxy group in the main resin, the adhesion on various different substrates is effectively improved, one paint is used for multiple purposes, the production efficiency is improved, and the waste is reduced; the solvent type isocyanate curing agent is matched, the use time limit is prolonged, the overall formula cost is reduced, and the same level as the solvent type paint is reached.

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

[0047] 1. The water-based two-component polyurethane primer of the present application is crosslinked by the cross-reaction of a water-based hydroxyl acrylic resin containing a small amount of epoxy groups and an isocyanate curing agent, and by the addition of suitable conductive carbon black, wetting agents, film-forming aids, thickening agents, and the like, so that the polyurethane primer obtained can have both wetting and leveling and anti-sagging when spin-disk electrostatically coated, and shows excellent appearance effects.

[0048] 2. The water-based polyurethane primer of the present application, which is composed of a wetting agent, a film-forming aid, and a thickening agent in combination with other components, and is matched with a solvent-type isocyanate curing agent, can achieve the same appearance and performance as solvent-type coatings under the condition of low VOC, and due to the incorporation 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 steel substrates.

[0049] 3. The present application can overcome the adverse effects of substrates and equipment without changing the coating process, ensuring the mechanical and weathering properties of the coating, solving various problems in the coating process, providing more excellent appearance, improving product yield, improving production efficiency, and using solvent-type curing agents, with longer activation period and lower cost. The water-based two-component polyurethane primer provided by the present application has good application prospects in plastic substrate coating. DETAILED DESCRIPTION

[0050] The content of the present application will be further described in detail through specific examples. It should also be understood that the following examples are only used to further illustrate the present application, and cannot be understood as limiting the scope of protection of the present application. Some non-essential improvements and adjustments made by those skilled in the art based on the principles described in the present application are within the scope of protection of the present application. The following examples specifically illustrate the process parameters, etc. which are only one example in the appropriate range, i.e. those skilled in the art can make appropriate choices within the range through the description herein, and are not limited to the specific data of the following examples. The raw materials, reagents or devices used in the following examples and comparative examples can be obtained from conventional commercial channels, or can be obtained by existing known methods, unless otherwise specified.

[0051] It should be noted that some of the raw materials used in the following examples and comparative examples of the present application are as follows:

[0052] The epoxy group-containing waterborne hydroxyl acrylic resin is a waterborne hydroxyl acrylic resin containing 8 wt% of epoxy groups; the solvent type isocyanate curing agent TPA100 is purchased from Asahi Kasei Corporation; VXR72 conductive carbon black is purchased from Cabot Corporation; Coapur XS83 is purchased from Akema Corporation; Rheolate 299 is purchased from Hemenis Corporation; TEGO 4000 and TEGO 4100, TEGO Foamex 810, TEGO AIREX 901W and AIREX 902W are purchased from Evonik Corporation; FLOW 487U and FLOW 488 are purchased from Occo Corporation; BYK 2012 and BYK 190 are purchased from BYK Corporation.

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

[0054] Example 1

[0055] A waterborne two-component polyurethane primer is prepared according to the following specific preparation steps:

[0056] S1, 3.5 parts of VXR72 conductive carbon black is ground to a fineness of less than 20 microns with 2.5 parts of BYK 2012, 0.4 parts of Foamex 810 and 7 parts of deionized water to form a carbon black slurry for later use. 50 parts of epoxy group-containing waterborne hydroxyl acrylic resin, 30 parts of deionized water, 1 part of TEGO 4000, 1 part of FLOW 487U, 0.5 part of AIREX 901W, 1 part of Coapur XS83, 1 part of Rheolate 299, 0.3 part of diethanolamine, 5 parts of dipropylene glycol methyl ether, and 5 parts of dipropylene glycol butyl ether are weighed and stirred uniformly, and then the ground carbon black slurry is added to the above mixture to prepare component A; the pH value of component A is 8-10;

[0057] S2, 70 parts of isocyanate curing agent TPA100 and 30 parts of dipropylene glycol methyl ether acetate are weighed and stirred uniformly to prepare component B;

[0058] S3, 100 parts of component A and 12 parts of component B are mixed to prepare a waterborne two-component polyurethane primer.

[0059] Example 2

[0060] A waterborne two-component polyurethane primer is prepared according to the following specific preparation steps:

[0061] S1, 4 parts of VXR72 conductive carbon black were ground with 3 parts of BYK2012, 0.5 parts of Foamex810 and 8 parts of deionized water to a fineness of less than 20 microns, ready for use. 45 parts of waterborne hydroxyl acrylate 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 were weighed, stirred uniformly, and then the ground carbon black slurry was added to the above mixture to prepare component A; the pH value of component A was 8-10;

[0062] S2, 75 parts of isocyanate curing agent TPA100 and 25 parts of dipropylene glycol methyl acetate were weighed, stirred uniformly to prepare component B;

[0063] S3, 100 parts of component A and 10 parts of component B were mixed to prepare a waterborne two-component polyurethane primer.

[0064] Example 3

[0065] A waterborne two-component polyurethane primer, which is different from example 1 in that:

[0066] In example 1, the film-forming aid dipropylene glycol methyl ether was replaced by propylene glycol methyl ether, and the other raw materials and preparation methods were the same as in example 1.

[0067] Example 4

[0068] A waterborne two-component polyurethane primer, which is different from example 1 in that:

[0069] In example 1, the film-forming aid dipropylene glycol butyl ether was replaced by alcohol ester twelve, and the other raw materials and preparation methods were the same as in example 1.

[0070] Example 5

[0071] A waterborne two-component polyurethane primer, which is different from example 1 in that:

[0072] In example 2, Rheolate299 was removed, and the other raw materials and preparation methods were the same as in example 2.

[0073] Example 6

[0074] A waterborne two-component polyurethane primer, which is different from example 1 in that:

[0075] In example 1, Coapur XS83 was removed, and the other raw materials and preparation methods were the same as in example 1.

[0076] Example 7

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

[0078] The TEGO 4000 in Example 1 is removed, and the rest of the raw materials and preparation method are the same as Example 1.

[0079] Example 8

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

[0081] The FLOW 488U in Example 2 is removed, and the rest of the raw materials and preparation method are the same as Example 1.

[0082] Comparative Example 1

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

[0084] The conductive carbon black VXR72 in Example 1 is replaced with ordinary carbon black, and the rest of the raw materials and preparation method are the same as Example 1.

[0085] Comparative Example 2

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

[0087] The TPA100 curing agent in Example 1 is replaced with KOSHI 2655 waterborne curing agent, and the amount is 14 parts.

[0088] Comparative Example 3

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

[0090] The TPA100 curing agent in Example 1 is replaced with DIAISDNW5500 waterborne curing agent, and the amount is 18 parts.

[0091] Comparative Example 4

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

[0093] The waterborne hydroxyl acrylic resin containing epoxy groups in Example 1 is replaced with ordinary hydroxyl acrylic resin without epoxy groups.

[0094] Comparative Example 5

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

[0096] The waterborne hydroxyl acrylic resin containing epoxy groups in Example 1 is replaced with epoxy resin, and the curing agent is replaced with polyamide curing agent, and the ratio is calculated according to the equivalent.

[0097] Performance test

[0098] The water-based two-component polyurethane primer obtained in Examples 1-8 and Comparative Examples 1-5 above was adjusted to a coating viscosity of 30 seconds in a Iwata 2# cup, and was then subjected to spin disc electrostatic coating on a helmet production line to test the coating effect. The specific effects are shown in Table 1. Among them, the adhesion was tested according to GB / T 9286-2021; the hardness was pencil hardness; the wetting property, leveling property, and anti-sagging property were obtained by visual observation.

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

[0100]

[0101] As can be seen from Table 1, the polyurethane primer of Examples 1-8 is obviously superior to the polyurethane primer obtained in Comparative Examples 1-5 in terms of comprehensive adhesion, atomization effect, wetting property, leveling property, and anti-sagging property. Since Comparative Example 1 does not add conductive carbon black but uses ordinary carbon black, the adhesion, atomization effect, wetting property, and leveling property of the paint are all poor. Since the solvent-based curing agent can be used, the activation period and cost of Examples 1-2 are obviously superior to the water-based curing agent used in Comparative Examples 2-3. Comparative Example 4 uses a common hydroxyl acrylic resin that does not contain an epoxy group, which has 0-level adhesion on ABS and PC, but poor adhesion on glass steel. Comparative Example 5 uses an epoxy resin, which has qualified adhesion on glass steel, but no adhesion on plastics such as ABS and PC, so the two resins used in Comparative Examples 4-5 cannot be used on various plastic substrates, and two or more different primers need to be used to solve the adhesion problem, affecting daily production.

[0102] In Examples 1-8, the polyurethane primer of Examples 1-2 is superior to the polyurethane primer obtained in Examples 3-8. The film-forming aids used in Examples 3-4 are not as good as those in Examples 1-2, resulting in a decrease in wetting property, leveling property, and anti-sagging property. Examples 5-6 only use one thickening agent, which has a thickening effect that is not as good as that of Examples 1-2, resulting in a significant decrease in anti-sagging property. Examples 7-8 only use one wetting agent, which has a wetting effect that is not as good as that of Examples 1-2, resulting in a decrease in wetting property and leveling property.

[0103] The water-based two-component polyurethane primer in the embodiment of the present application is crosslinked by the crosslinking reaction of a water-based hydroxyl acrylic resin containing a small amount of epoxy groups and a solvent-type isocyanate curing agent, and the obtained polyurethane primer can have both wetting and leveling and anti-sagging when being electrostatically coated by a rotary disc, and shows excellent appearance effect. Since the components such as the wetting agent, the film-forming aid and the thickening agent are reasonably composed in the embodiment of the present application, the water-based polyurethane primer can be matched with the solvent-type isocyanate curing agent, so that the water-based polyurethane primer has low VOC, and has the same appearance and performance as the solvent-type coating, and since a small amount of epoxy groups are introduced into the resin, the coating has excellent adhesion on ABS and PC, and also has excellent adhesion on glass steel substrate.

[0104] The embodiment of the present application can overcome the adverse effects of the substrate and the equipment, solve various problems in the coating process, provide more excellent appearance, improve product yield, improve production efficiency, and use solvent-type curing agent, and has longer activation period and lower cost, under the condition of not changing the coating process and ensuring the mechanical and weather resistance of the coating. The water-based two-component polyurethane primer provided by the embodiment of the present application has good application prospect in plastic substrate coating.

[0105] In summary, the water-based two-component polyurethane primer of the present application can help the coating to wet the substrate, overcome the adverse effects of the low surface tension of the substrate and the coating equipment on the construction, have both leveling and anti-sagging, effectively improve the adhesion on various different substrates by introducing epoxy groups into the main resin, achieve one paint for multiple uses, improve production efficiency and reduce waste, match with the solvent-type isocyanate curing agent, prolong the use time limit, reduce the overall formulation cost, and reach the same level as the solvent-type coating.

Claims

1. An aqueous two-component polyurethane primer, characterized in that, comprising a Group A component and a Group B component, wherein the Group A component comprises the following components by mass fraction: an aqueous hydroxyl acrylic resin 40-60 parts; conductive carbon black 3-4 parts; a film forming aid 3-6 parts; a thickening agent 0.5-1 part; a wetting agent 0.5-1 part; an antifoaming agent 0.3-0.5 parts; a wet dispersing agent 2-3 parts; a pH adjusting agent 0.1-0.5 parts; water 20-40 parts; the Group B component comprises the following components by mass fraction: a solvent type isocyanate curing agent 70-80 parts; a solvent 20-30 parts; the aqueous hydroxyl acrylic resin is selected from an aqueous hydroxyl acrylic resin containing an epoxy group; in the Group A component, the film forming aid comprises a first film forming aid and a second film forming aid; the first film forming aid comprises 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 comprises at least one of dipropylene glycol butyl ether, alcohol ester twelve, ethylene glycol butyl ether or propylene glycol butyl ether; in the Group A component, the thickening agent comprises a first thickening agent and a second thickening agent; the first thickening agent is selected from a polyurethane thickening agent; the second thickening agent is selected from a polyether polyurethane thickening agent; in the Group A component, the wetting agent comprises a first wetting agent and a second wetting agent; the first wetting agent is selected from a gemini type silicone wetting agent; the second wetting agent is selected from a modified silicone wetting agent.

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

3. The aqueous two-component polyurethane primer of claim 1, wherein, an epoxy group content in the aqueous hydroxyl acrylic resin containing an epoxy group is 5-10 wt%.

4. The aqueous two-component polyurethane primer of claim 1, wherein, in the Group A component, the antifoaming agent is selected from a polyether siloxane copolymer antifoaming agent containing fumed silica; and / or, in the Group A component, the wet dispersing agent is selected from a copolymer wet dispersing agent containing a pigment affinity group; and / or, in the Group A component, the pH adjusting agent comprises at least one of monoethanolamine, diethanolamine, triethanolamine or ammonia water; and / or, a pH value of the Group A component is 7-11.

5. The aqueous two-component polyurethane primer of claim 1, wherein, in the Group B component, the solvent type isocyanate curing agent comprises at least one of hexamethylene diisocyanate curing agent, diphenylmethane diisocyanate curing agent or toluene diisocyanate curing agent; and / or, in the Group B component, the solvent comprises at least one of propylene glycol methyl ether acetate, propylene glycol diacetate, ethyl acetate, butyl acetate, cyclohexanone or xylene.

6. A process for the preparation of an aqueous two-component polyurethane primer according to any one of claims 1 to 5, characterized in that, comprising the following steps: S1, mixing conductive carbon black, a wet dispersing agent, part of an antifoaming agent and part of water to obtain a carbon black slurry; mixing an aqueous hydroxyl acrylic resin, a film forming aid, a thickening agent, a wetting agent, a pH adjusting agent, the rest of the antifoaming agent and the rest of the water to obtain a resin dispersion; adding the carbon black slurry into the resin dispersion to obtain a Group A component; S2, mixing a solvent type isocyanate curing agent and a solvent to obtain a Group B component; S3, mixing the Group A component and the Group B component to obtain the aqueous two-component polyurethane primer.

7. Application of the aqueous two-component polyurethane primer according to any one of claims 1-5 in plastic substrate coating.

8. Use according to claim 7, characterized in that, The plastic substrate is made of at least one of acrylonitrile-butadiene-styrene copolymer, polycarbonate or glass fiber reinforced plastic.

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