An environmentally friendly two-component waterborne fluorocarbon coating and its preparation method

Abstract

The present invention discloses an environment-friendly two-component waterborne fluorocarbon coating, belonging to the technical field of coatings, which comprises component A and component B; Component A comprises the following components in parts by weight: 55-70 parts of waterborne fluorocarbon resin, 5-15 parts of water, 15-25 parts of pigment, 0.5-2 parts of dispersant, 0.5-2 parts of wetting dispersant A, 0.5-2 parts of wetting agent, 0.5-1.5 parts of thickener, 0.2-1 part of leveling agent, 0.2-0.6 part of defoamer; Component B comprises the following components in parts by weight: 11-17 parts of solvent-free waterborne isocyanate curing agent, 0.5-2 parts of wetting dispersant B. The environment-friendly two-component waterborne fluorocarbon coating of the present invention has excellent corrosion resistance, excellent weather resistance, high gloss and high hardness. The two-component waterborne fluorocarbon coating does not contain any VOC-containing components, truly realizes zero VOC, and has good environmental protection and broad application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and particularly relates to an environmentally friendly two-component waterborne fluorocarbon coating and a preparation method thereof. Background Art

[0002] Fluorocarbon coatings have excellent weather resistance, chemical corrosion resistance, and stain resistance, and are a type of anti-corrosion topcoat with excellent performance. For projects with high requirements such as large-scale steel structures, heavy anti-corrosion, and high weather resistance, fluorocarbon coatings with excellent performance are generally selected, which can greatly reduce the later maintenance costs.

[0003] Solvent-based fluorocarbon coatings have been widely used in different fields, especially in the anti-corrosion field. Many solvent-based fluorocarbon coating projects still maintain a certain gloss and color after more than twenty years of testing, and no serious corrosion has occurred, which fully proves that fluorocarbon coatings have strong competitiveness in high-end fields. However, as China's laws and regulations have increasingly strict environmental protection requirements, especially the emission restrictions on volatile organic compounds (VOCs) are becoming stricter, resulting in solvent-based fluorocarbon coatings sometimes unable to meet the emission requirements. Therefore, the waterborne transformation of solvent-based fluorocarbon coatings has become a trend.

[0004] Waterborne fluorocarbon coatings have the advantages of low environmental harm, convenient construction, good safety, easy storage and transportation, etc. They will be more and more widely used in the future and are expected to completely replace solvent-based fluorocarbon coatings in the future. Among them, single-component thermoplastic waterborne fluorocarbon coatings have been popularized and applied on building facades, but there is still a large gap in performance between thermoplastic waterborne fluorocarbon coatings and solvent-based fluorocarbon coatings in the anti-corrosion field. If you want to approach the performance of solvent-based fluorocarbon coatings, a two-component waterborne fluorocarbon coating with external cross-linking must be used.

[0005] Although waterborne coatings use water as a diluent, solvents (also called co-solvents, film-forming aids) are also essential in waterborne coatings. The role of film-forming aids is to help film formation. If film-forming aids are not added to waterborne coatings, surface abnormalities such as film cracking may occur. For example, the minimum film-forming temperature of a certain film-forming substance is 25°C. Adding film-forming aids can help reduce the film-forming temperature, and better film formation can occur at 5°C, forming a denser film. The role of co-solvents is to control the drying speed of two-component films. Adding fast-drying co-solvents will cause problems such as film blistering and poor surface leveling, and adding slow-drying co-solvents will cause defects such as long-term non-drying of the film and dust accumulation on the surface. Film-forming aids and co-solvents are the main sources of VOCs in waterborne paints.

[0006] Therefore, how to provide an environmentally friendly two-component waterborne fluorocarbon coating with excellent anti-corrosion performance has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0007] The object of the present invention is to overcome the deficiencies of the prior art and provide an environmentally friendly two-component waterborne fluorocarbon coating and its preparation method. The environmentally friendly two-component waterborne fluorocarbon coating has excellent corrosion resistance, excellent weather resistance, high gloss, and high hardness. The two-component waterborne fluorocarbon coating does not contain any VOC-containing components, truly achieving zero VOC, and has good environmental protection and broad application prospects.

[0008] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] An environmentally friendly two-component waterborne fluorocarbon coating, comprising component A and component B;

[0010] Component A comprises the following components in parts by weight: 55-70 parts of waterborne fluorocarbon resin, 5-15 parts of water, 15-25 parts of pigment, 0.5-2 parts of dispersant, 0.5-2 parts of wetting dispersant A, 0.5-2 parts of wetting agent, 0.5-1.5 parts of thickener, 0.2-1 part of leveling agent, 0.2-0.6 part of defoamer;

[0011] Component B comprises the following components in parts by weight: 11-17 parts of solvent-free waterborne isocyanate curing agent, 0-2 parts of wetting dispersant B;

[0012] The fluorine content of the waterborne fluorocarbon resin is 24-25 wt%, and the hydroxyl content is 2.6-3.1 wt%.

[0013] By combining the above raw materials in specific parts by weight, the present invention obtains a two-component waterborne fluorocarbon coating with excellent corrosion resistance, excellent weather resistance, high gloss, and high hardness without adding cosolvent and film-forming aid. The two-component waterborne fluorocarbon coating does not contain any VOC-containing components, truly achieving zero VOC, and has good environmental protection and broad application prospects.

[0014] The present invention creatively adopts a waterborne fluorocarbon resin with a fluorine content of 24-25 wt% and a hydroxyl content of 2.6-3.1 wt%. For the resin with such fluorine content and hydroxyl content, the F element is directly connected to the main chain, and can crosslink in the system to form a three-dimensional interpenetrating crosslinked network, effectively improving the corrosion resistance, anti-aging performance and hardness of the system.

[0015] The inventors of the present invention have found through research that if the content of the F element is insufficient or the F element is connected to the side chain, it will lead to a significant decrease in the corrosion resistance, anti-aging performance and hardness of the system. If the hydroxyl content is too low, the crosslinking degree is insufficient. If the hydroxyl content is too high, excessive crosslinking will occur, resulting in poor compatibility and stability of the system, and thus also leading to a decrease in performance.

[0016] Preferably, representative waterborne fluorocarbon resins are waterborne fluorocarbon resin ETERFLON 43302 and waterborne fluorocarbon resin WFD-2245.

[0017] Among them, the fluorine content of waterborne fluorocarbon resin ETERFLON 43302 is 24 wt%, and the hydroxyl content is 2.6 wt%.

[0018] The fluorine content of waterborne fluorocarbon resin WFD-2245 is 25 wt%, and the hydroxyl content is 3.03 wt%.

[0019] As a preferred embodiment of the present invention, the solvent-free waterborne isocyanate curing agent is an HDI hydrophilic trimer, and the viscosity of the solvent-free waterborne isocyanate curing agent at 25 °C ≤ 2500 mPa·s.

[0020] Preferably, the NCO content of the solvent-free waterborne isocyanate curing agent is 17.2 - 17.8 wt%

[0021] The inventors of the present invention found that since the system of the present invention is completely solvent-free, therefore, a hydrophilic trimer with a viscosity ≤ 2500 mPa·s needs to be added to form a three-dimensional interpenetrating cross-linked network with the above-mentioned specific waterborne fluorocarbon resin, effectively improving the corrosion resistance, aging resistance and hardness of the system. If other curing agents are used, either an oil-water incompatible turbid situation will occur, or they cannot be dispersed evenly. Therefore, the present invention needs to use a hydrophilic trimer with a viscosity ≤ 2500 mPa·s as the curing agent.

[0022] Among them, a representative solvent-free waterborne isocyanate curing agent is Bayhydur 3100, its viscosity at 25 °C is 2500 mPa·s, the solid content is 100%, and the NCO content is 17.4 wt%.

[0023] Meanwhile, under the specific system of the present invention, in component B of the present invention, if the wetting and dispersing agent B is not added, the aging resistance and gloss will decrease.

[0024] As a preferred embodiment of the present invention, the defoaming agent is a polyether polysiloxane copolymer emulsion type defoaming agent.

[0025] The inventors of the present invention have studied and found that the type of defoaming agent has a significant impact on the effect. The present invention uses a polyether polysiloxane copolymer emulsion type defoaming agent, which has a relatively small interfacial tension difference from the waterborne fluorocarbon resin of the present invention (compared with other defoaming agents), good compatibility, and can effectively avoid phenomena such as film shrinkage pores, thereby obtaining a film with good appearance. If other types of defoaming agents are used, film shrinkage pores are very likely to occur, resulting in the paint being unusable.

[0026] Among them, the representative polyether silicone copolymer emulsion defoamer istego Airex 902W.

[0027] As a preferred embodiment of the present invention, the leveling agent is a hydroxyl-functional group-containing silicone polyether modified surfactant.

[0028] The inventors of the present invention found that in the system of the present invention, most of the additives in the coating are evenly distributed throughout the paint film system, but the leveling agent is mainly distributed on the outer surface of the paint film to improve the surface effect of the paint film. The principle is that during the surface drying of the wet film, the leveling agent will migrate to the surface of the paint film. The advantage is to achieve the purpose of improving leveling, and the disadvantage is that the migration of small molecule substances on the surface of the dried paint film affects weather resistance, corrosion resistance and gloss. The present invention creatively uses a hydroxyl-functional group-containing silicone polyether modified surfactant as the leveling agent. When it migrates to the surface, it can participate in the curing reaction of the system and firmly fix it on the surface, thus avoiding the decline of weather resistance, corrosion resistance and gloss.

[0029] Among them, the representative leveling agent (hydroxyl-functional group-containing silicone polyether modified surfactant) is Dow Corning DC29.

[0030] As a preferred embodiment of the present invention, the dispersant is a high molecular weight block copolymer solution containing a pigment affinity group.

[0031] Using a high molecular weight block copolymer solution containing a pigment affinity group can deflocculate the pigment through steric hindrance stabilization, improving the compatibility and stability of the system.

[0032] Among them, the representative high molecular weight block copolymer solution containing a pigment affinity group is at least one of DISPERBYK-190, DISPERBYK-182, DISPERBYK-184, DISPERBYK-185, DISPERBYK-161, DISPERBYK-162, DISPERBYK-163, DISPERBYK-154, DISPERBYK-170.

[0033] As a preferred embodiment of the present invention, the wetting dispersant A is a polyamide wetting dispersant.

[0034] As a preferred embodiment of the present invention, the wetting dispersant B is a polyamide wetting dispersant.

[0035] Among them, the representative polyamide wetting dispersants are at least one of Disuper S9100 and the universal water-oil dispersant HT-5082.

[0036] As a preferred embodiment of the present invention, the wetting agent is a silicone-based wetting agent.

[0037] Among them, a representative silicone-based wetting agent is TEGO Wet 270.

[0038] As a preferred embodiment of the present invention, the thickener is a non-ionic polyurethane associative thickener.

[0039] Exemplarily, the pigments include but are not limited to colors such as white, black, yellow, blue, green, pink, red, orange, purple, indigo, brown, and combinations thereof. More particularly, the pigments can be white and blue, for example, one of those listed in the International Color Index.

[0040] The present invention also provides a method for preparing an environmentally friendly two-component waterborne fluorocarbon coating, comprising the following steps:

[0041] Mix water, a wetting agent, wetting dispersant A, and part of the defoaming agent evenly, then add pigments and mix evenly. Then add waterborne fluorocarbon resin, wetting agent, leveling agent, the other part of the defoaming agent, and thickener, stir evenly, filter and discharge to obtain Component A;

[0042] After mixing Component B evenly according to the ratio, add it to Component A and stir evenly to obtain an environmentally friendly two-component waterborne fluorocarbon coating.

[0043] The beneficial effects of the present invention are as follows: Without adding cosolvents and film-forming aids, the present invention obtains a two-component waterborne fluorocarbon coating with excellent corrosion resistance, excellent weather resistance, high gloss, and high hardness. The two-component waterborne fluorocarbon coating does not contain any VOC-containing components, truly achieving zero VOC, and has good environmental protection and broad application prospects. Specific Embodiments

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below. Apparently, the described embodiments are some, but not all, of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present application.

[0045] In the present application, among the technically characterized described in an open-ended manner, a closed technical solution composed of the listed features is included, as well as an open-ended technical solution including the listed features.

[0046] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are considered continuous and include the minimum and maximum values of the range, as well as each value between such minimum and maximum values. Further, when the range refers to integers, it includes each integer between the minimum and maximum values of the range. In addition, when multiple ranges are provided to describe features or characteristics, these ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0047] The raw materials used in the examples and comparative examples are described as follows:

[0048] Waterborne fluorocarbon resin - 1: Fluorine content is 24 wt%, hydroxyl content is 2.6 wt%, Changxing Chemical, ETERFLON43302.

[0049] Waterborne fluorocarbon resin - 2: Fluorine content is 25 wt%, hydroxyl content is 3.03 wt%, Wanbo New Materials Technology (Nantong) Co., Ltd., WFD - 2245.

[0050] Waterborne fluorocarbon resin - 3: Fluorine content is 23 wt%, hydroxyl content is 1.5 wt%, Changxing Chemical, ETERFLON43030.

[0051] Waterborne fluorocarbon resin - 4: Fluorine content is 24 wt%, hydroxyl content is 2.0 wt%, Guangzhou Guanzhi New Materials Technology Co., Ltd., PA - 4200F.

[0052] Dispersant: High - molecular - weight block copolymer solution containing pigment - affinity groups, DISPERBYK - 190, Degussa, DISPERBYK - 190.

[0053] Wetting dispersant - 1: Polyamide - based wetting dispersant, Core Chemical, Disuper S9100.

[0054] Wetting dispersant - 2: Polycarboxylate - based wetting dispersant, BYK, BYK - 192.

[0055] Titanium dioxide: Chemours, R706.

[0056] Wetting agent: Organosilicon - based wetting agent, Degussa, TEGO Wet 270.

[0057] Leveling agent - 1: Organosilicon polyether - modified surfactant containing hydroxyl functional groups, Dow Corning, DC29.

[0058] Leveling agent - 2: Polyether - modified polydimethylsiloxane, BYK, BYK - 3455.

[0059] Defoamer - 1: Polyether silicone copolymer emulsion defoamer, Degussa,tego Airex 902W.

[0060] Defoamer - 2: Polyether silicone copolymer, Degussa, Airex 901W.

[0061] Thickener - 1: Non - ionic polyurethane associative thickener, Rohm and Haas ASEA, RM - 2020.

[0062] Thickener - 2: Alkali - swellable acrylic thickener, Heimtex Specialty Chemicals, Rheolate 125, solid content 25%.

[0063] Curing agent - 1: Solvent - free water - borne isocyanate curing agent (HDI hydrophilic trimer), viscosity at 25 °C is 2500 mPa·s, Covestro, Bayhydur 3100.

[0064] Curing agent - 2: TDI curing agent (benzene ring structure, containing 25% ethyl acetate solvent), Covestro Desmodur1451.

[0065] Curing agent - 3: Solvent - free water - borne isocyanate curing agent (HDI hydrophilic trimer), viscosity at 25 °C is 3500 mPa·s, Covestro, XP2655.

[0066] Unless otherwise specified, the component raw materials used in each example and comparative example of the present invention are all commercially available raw materials, and the component raw materials used in each parallel experiment are of the same kind.

[0067] Examples 1 - 4, Comparative Examples 1 - 10

[0068] The formulations of the environmentally friendly two - component water - borne fluorocarbon coatings of Examples 1 - 4 and Comparative Examples 1 - 10 are shown in Table 1 and Table 2 (in parts by weight).

[0069] Among them, the preparation methods of the environmentally friendly two - component water - borne fluorocarbon coatings of Examples 1 - 4 and Comparative Examples 1 - 10 all include the following steps:

[0070] According to the ratio, mix water, wetting agent, wetting and dispersing agent A and part of the defoamer (40% of the total defoamer) evenly, then add pigments and mix evenly, then add water - borne fluorocarbon resin, wetting agent, leveling agent, the other part of the defoamer, and thickener, stir evenly, filter and discharge to obtain Component A;

[0071] After mixing Component B evenly according to the ratio, add it to Component A and stir evenly to obtain the environmentally friendly two - component water - borne fluorocarbon coating.

[0072] Table 1

[0073]

[0074]

[0075] Performance test

[0076] Test method:

[0077] The artificial weathering accelerated test is carried out according to the provisions of "Exposure cycle type 7" in the appendix of GB / T 14522-2008. The test time is 4000 h, and the loss of gloss rate is calculated.

[0078] The test for resistance to liquid media is carried out according to the provisions of GB / T 9274-1998.

[0079] The pencil hardness is determined according to the provisions of GB / T 6739.

[0080] The gloss is determined according to the provisions of GB / T 9754.

[0081] Table 2

[0082]

[0083] As can be seen from Table 1, the environmentally friendly two-component waterborne fluorocarbon coating described in the present invention has excellent corrosion resistance, excellent weather resistance, high gloss and high hardness. The two-component waterborne fluorocarbon coating does not contain any VOC-containing components, truly achieving zero VOC, and has good environmental protection and broad application prospects.

[0084] Comparing Example 1 with Comparative Examples 1-2, it can be seen that the amount of the waterborne fluorocarbon resin has a significant influence on the effect. In the present invention, the amount of the waterborne fluorocarbon resin needs to be strictly controlled. If the amount of the waterborne fluorocarbon resin is too low or too high, the performance will decrease.

[0085] Comparing Example 1 with Comparative Examples 3-4, it can be seen that the waterborne fluorocarbon resin with a fluorine content of 24-25 wt% and a hydroxyl content of 2.6-3.1 wt% used in the present invention significantly improves the weather resistance and corrosion resistance.

[0086] Comparing Example 1 with Comparative Examples 5 and 6, it can be seen that if other types of curing agents are used, the performance will decrease significantly.

[0087] Comparing Example 1 with Comparative Examples 7-8, it can be seen that in the present invention, in order to obtain a coating with high gloss, a polyamide wetting and dispersing agent needs to be added to Component B. If other types of wetting and dispersing agents are used, the gloss will decrease.

[0088] Comparing Example 1 with Comparative Example 9, it can be seen that the polyether silicone copolymer emulsion defoamer used in the present invention has a relatively small interfacial tension difference with the aqueous fluorocarbon resin of the present invention (compared with other defoamers), good compatibility, and can effectively avoid phenomena such as film shrinkage pores, thereby obtaining a film with good appearance. If other types of defoamers are used, film shrinkage pores are likely to occur, resulting in the paint being unusable.

[0089] Comparing Example 1 with Comparative Example 10, it can be seen that the present invention uses an organosilicon polyether modified surfactant containing a hydroxyl functional group as a leveling agent. When it migrates to the surface, it can participate in the curing reaction of the system and firmly fix it on the surface, thereby avoiding a decrease in weather resistance, corrosion resistance, and gloss.

[0090] Comparing Example 1 with Comparative Example 11, it can be seen that the use of the non-ionic polyurethane associative thickener of the present invention significantly improves the corrosion resistance.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. An environmentally friendly two-component waterborne fluorocarbon coating, characterized in that, It includes Component A and Component B; Component A includes the following components by weight: 55 - 70 parts of waterborne fluorocarbon resin, 5 - 15 parts of water, 15 - 25 parts of pigment, 0.5 - 2 parts of dispersant, 0.5 - 2 parts of wetting dispersant A, 0.5 - 2 parts of wetting agent, 0.5 - 1.5 parts of thickener, 0.2 - 1 part of leveling agent, 0.2 - 0.6 part of defoamer; Component B includes the following components by weight: 11 - 17 parts of solvent-free waterborne isocyanate curing agent, 0.5 - 2 parts of wetting dispersant B; The fluorine content of the waterborne fluorocarbon resin is 24 - 25 wt%, and the hydroxyl content is 2.6 - 3.1 wt%; The environment-friendly two-component waterborne fluorocarbon coating does not contain cosolvent and film-forming auxiliary; The solvent-free waterborne isocyanate curing agent is an HDI hydrophilic trimer, and the viscosity of the solvent-free waterborne isocyanate curing agent at 25 °C ≤ 2500 mPa.s; The defoamer is a polyether silicone copolymer emulsion type defoamer; The leveling agent is an organosilicon polyether modified surfactant containing hydroxyl functional groups; The wetting dispersant B is a polyamide type wetting dispersant; The thickener is a non-ionic polyurethane associative thickener.

2. The environmentally friendly two-component waterborne fluorocarbon coating according to claim 1, wherein The dispersant is a high molecular weight block copolymer solution containing pigment affinity groups.

3. The environmentally friendly two-component waterborne fluorocarbon coating according to claim 1, wherein The wetting dispersant A is a polyamide type wetting dispersant.

4. The environmentally friendly two-component waterborne fluorocarbon coating according to claim 1, wherein The wetting agent is an organosilicon type wetting agent.

5. The preparation method of the environment-friendly two-component waterborne fluorocarbon coating according to any one of claims 1 to 4, characterized in that It includes the following steps: Mix water, wetting agent, wetting dispersant A and part of the defoamer evenly, then add the pigment and mix evenly, then add waterborne fluorocarbon resin, wetting agent, leveling agent, the other part of the defoamer, and thickener, stir evenly, filter and discharge to obtain Component A; After mixing Component B evenly according to the ratio, add it to Component A and stir evenly to obtain the environment-friendly two-component waterborne fluorocarbon coating.

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