Titanium dioxide micro-nanocontainers, corrosion-resistant waterborne epoxy coating and preparation method thereof

Abstract

A titanium dioxide micro-nanocontainers, corrosion-resistant waterborne epoxy coatings and preparation method thereof, including preparation steps as follows: TiO.sub.2 micro-nano spheres are synthesized by applying hydrothermal method; a polyaniline layer doped with molybdate ions is deposited on the surface of TiO.sub.2 micro-nano spheres by adopting the method of in-situ chemical polymerization, TiO.sub.2/PANI-MoO.sub.4.sup.2? micro-nano-spheres are obtained, then, polydopamine is encapsulated on the surface of TiO.sub.2/PANI-MoO.sub.4.sup.2? micro-nano spheres to obtain titanium dioxide micro-nanocontainers; next, antirust filler, defoamer, dispersant and thickener are added into waterborne epoxy emulsion, then titanium dioxide micro-nanocontainers are added in the waterborne epoxy emulsion for dispersing and grinding, filtering and encapsulating to obtain component A; the waterborne epoxy curing agent and deionized water are mixed in proportion to obtain component B; component A is stirred, then it is mixed with the component B in proportion, corrosion-resistant waterborne epoxy coatings is obtained. According to the invention, the titanium dioxide micro-nanocontainers is synthesized and added into the coating as an additive, which can not only improve the compatibility between the filler and the emulsion, but greatly improves the long-term corrosion resistance of the coating by prolonging the release time of the corrosion inhibitors.

Claims

1. A preparation method of titanium dioxide micro-nanocontainers doped with molybdate corrosion inhibitors, including three preparation steps as follows: step 1, synthesizing TiO.sub.2 micro-nano spheres by using the hydrothermal method, specifically comprising: dissolving ammonium fluoride in ultrapure water to obtain an ammonium fluoride solution, next, using TiCl.sub.4 as titanium source, slowly dropping it into the ammonium fluoride solution, then pouring the mixture into a hydrothermal reactor, carrying out reaction at 150-170? C. for 4-8 h, centrifuging the reaction product after cooling it to room temperature, washing and drying the centrifuged product to obtain TiO.sub.2 micro-nano spheres; step 2, depositing a polyaniline layer doped with molybdate ions on the surface of TiO.sub.2 micro-nano spheres by using the in-situ polymerization method, obtaining TiO.sub.2/PANI-MoO.sub.4.sup.2? micro-nano spheres, specifically comprising: adding TiO.sub.2 micro-nano spheres, sodium dodecyl sulfate, molybdate and aniline into water, mixing and dissolving the materials to obtain a mixed solution, then, slowly dripping ammonium persulfate into the mixed solution in an ice bath environment, and stirring the mixed solution while dripping until the color of the solution changes from white to dark green, completing in-situ polymerization of polyaniline and dope of MoO.sub.4.sup.2? on the surface of TiO.sub.2 micro-nano spheres, carrying out complete reaction, washing and drying the reacted material to obtain TiO.sub.2/PANI-MoO.sub.4.sup.2? micro-nano spheres; step 3, encapsulating polydopamine on the surface of TiO.sub.2/PANI-MoO.sub.4.sup.2? micro-nano spheres, obtaining titanium dioxide micro-nanocontainers doped with molybdate corrosion inhibitors, specifically comprising: adding dopamine and TiO2/PANI-MoO42- micro-nano spheres into Tris-HCl buffer solution to obtain a mixture, stirring the mixture for reaction for 8-14 h, centrifugal washing and drying the reaction product to obtain polydopamine modified titanium dioxide micro-nanocontainers.

2-4. (canceled)

5. A corrosion-resistant waterborne epoxy coating, wherein, a formula of the corrosion-resistant waterborne epoxy coating, consisting of component A and component B, and materials in each component is calculated in parts by mass as the following table illustrates: TABLE-US-00005 Component A Waterborne epoxy emulsion 35~55 parts Titanium dioxide micro-nanocontainers 0~10 parts Anti-rust fillers 15~40 parts Defoamer 0.5~5 parts Dispersant 0.5~5 parts Thickener 0~5 parts Component B Waterborne epoxy curing agent 7~15 parts Water 0~10 parts wherein, the described titanium dioxide micro-nanocontainers is prepared by the preparation method claimed in claim 1, and a content of the titanium dioxide micro-nanocontainers is not equal to 0.

6. The corrosion-resistant waterborne epoxy coating as claimed in claim 5, the filler is one or a selective combination of zinc phosphate, aluminum tripolyphosphate, barium sulfate, talcum powder, silicon micro-powder and mica flakes.

7. The corrosion-resistant waterborne epoxy coating as claimed in claim 5, the waterborne epoxy emulsion is any one or a combination of type I epoxy emulsion with epoxy equivalent of about 190 and type II epoxy emulsion with epoxy equivalent of about 500.

8. The corrosion-resistant waterborne epoxy coating as claimed in claim 5, the dispersant is anionic dispersant for waterborne coating; the defoamer is silicone defoamer; the thickener is one or a selective combination of fumed silica, organo bentonite and polyamide wax slurry.

9. The corrosion-resistant waterborne epoxy coating as claimed in claim 5, the waterborne epoxy curing agent is any one or more of amidated polyamine, polyamide and epoxy-polyamine adduct.

10. A preparation method of the corrosion-resistant waterborne epoxy coating as claimed in claim 5, comprising three preparation steps as follows: step 1, adding the anti-rust filler, defoamer, dispersant and thickener into the water-borne epoxy emulsion pursuant to the formula ratio, next, mixing and grinding the mixture for 1-3 h with the rotating speed is controlled a 2500+/?500 r/min, next, adding titanium dioxide micro-nanocontainers into the mixture for dispersion for 20-50 min, obtaining component A of the corrosion-resistant water-borne epoxy coating; step 2, mixing waterborne epoxy curing agent with deionized water in proportion, stirring the mixture at high speed for 20-50 min to obtain component B of the corrosion-resistant water-borne epoxy coating; step 3, stirring and curing the component A for 20-50 min, and mixing it evenly with the component B in proportion, obtaining the corrosion-resistant waterborne epoxy coating that can be immediately used.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0034] FIG. 1 illustrates a SEM image of titanium dioxide micro-nano spheres synthesized by hydrothermal method in Embodiment 1 of the present invention

[0035] FIG. 2 illustrates a SEM diagram of titanium dioxide micro-nanocontainers assembled layer by layer in Embodiment 1 of the present invention.

[0036] FIG. 3 illustrates 35 d salt spray test of corrosion-resistant waterborne epoxy coating containing titanium dioxide micro-nano spheres.

[0037] FIG. 4 illustrates 35 d salt spray test of corrosion-resistant waterborne epoxy coating containing titanium dioxide micro-nanocontainers.

DETAILED DESCRIPTION OF EMBODIMENTS

[0038] In order to better understand the present invention, the concrete embodiment of a corrosion-resistant waterborne epoxy coating containing titanium dioxide micro-nano containers and its preparation method, according to the present invention, was described in detail with reference to the attached drawings and examples. Furthermore, the scope and implementation of the present invention should not be limited by this.

Embodiment 1

[0039] The preparation of Titanium dioxide micro-nanocontainers doped with molybdate corrosion inhibitors is described as follows:

[0040] a) TiO.sub.2 micro-nano spheres were synthesized by hydrothermal method.

[0041] 2.96 g NH.sub.4F is dissolved in 200 mL ultrapure water to obtain a mixed solution, and 2.2 mL TiCl.sub.4 is slowly dripped into the solution, then, the mixture is poured into a hydrothermal reactor for reacting at 160? C. for 6 h. After cooling to room temperature, the precipitates had been separated by high-speed centrifugation and washed several times with ethanol and ultrapure water until they became powders, the obtained powders were dried at 70? C. for 12 h to form the TiO.sub.2 micro-nano spheres.

[0042] b) Polyaniline (PANI) layer doped with MoO.sub.4.sup.2? was deposited on the surface of TiO.sub.2 micro-nano spheres by using the in-situ polymerization method. 2.0 g TiO.sub.2 microspheres, 0.1 g SDS.sup.?, 0.1 g MoO.sub.4.sup.2? and 0.8 mL ANI were mixed in 100 mL water solution for 1 h, and then 25 mL of 0.1M (NH.sub.4).sub.2S.sub.2O.sub.8 was slowly dripped into the solution in an ice bath environment, the mixed solution changed from white to dark green, and in-situ polymerization of PANI and MoO.sub.4.sup.2? doping were carried out on the surface of TiO.sub.2 microspheres, kept mixing and stirring for 2 h to ensure a complete reaction, the reaction product was washed and drying, finally, TiO.sub.2/PANI-MoO.sub.4.sup.2? micro-nano spheres was obtained.

[0043] 50 mg DA and 0.25 g TiO.sub.2/PANI/MoO.sub.4.sup.2? micro-nano spheres were added into 50 mL Tris-HCl buffer solution (pH=8.5), the mixture was stirred for 12 h, then it was centrifugally washed and dried to obtain PDA-modified TiO.sub.2 micro-nanocontainers (TiO.sub.2/PANI-MoO.sub.4.sup.2?/PDA), which is the titanium dioxide micro-nanocontainers doped with molybdate inhibitors.

Embodiment 2

[0044] The preparation method of corrosion-resistant waterborne epoxy coating that contains titanium dioxide micro-nanocontainers comprises the following steps: [0045] According to the formula ratio, 20 parts of antirust filler, 3 parts of defoamer, 2 parts of dispersant and 2 parts of thickener were added into 52 parts of waterborne epoxy emulsion, and the rotation speed was controlled at 2500+/?500 r/min, the emulsion was mixed and ground for 2 h, 1 part of titanium dioxide micro-nanocontainers was added and dispersed for 30 min, wherein defoaming agent was added in three times, grinding fineness was ?60 ?m, and the powder was filtered and packaged with a filter screen to obtain component A of the corrosion-resistant waterborne epoxy coating, containing titanium dioxide micro-nanocontainers; [0046] 15 parts of waterborne epoxy curing agent and 5 parts of deionized water were mixed in proportion, and stirred at a high speed for 30 min to obtain component B of corrosion-resistant waterborne epoxy coating containing titanium dioxide micro-nano containers;

[0047] The component A was stirred and cured for 30 min, then mixed evenly with the component B in proportion, and coated on the surface of Q235 steel with a coating thickness of 100?5 ?m.

[0048] The performance test for the corrosion-resistant waterborne epoxy coating that contains micro-nanocontainers of the embodiment 2, and its cured coating. The test results were as follows in Table 1:

TABLE-US-00002 TABLE 1 Performance evaluation of the corrosion-resistant waterborne epoxy coating that contains micro-nanocontainers and its cured coating of embodiment 2 Test item Performance test Test standard State in Container After stirring evenly, Measuring by sight there are no lumps, and the mixture is uniform Coating appearance Earthly yellow Measuring by sight Surface drying time, h 4 GB/T 1728 Hard drying time, h 24 GB/T 1728 VOCs content, g/L 28.2 GB/T 23986 Applicable period 3 GB/T 31416 (normal temperature), h Film thickness, ?m 101 GB/T 13452.2 Adhesion with 8.9 GB/T 5210 substrate(Q235), MPa Hardness 3H GB/T 6739 shock resistance, cm 50 GB/T 1732 Neutral salt spray No blistering and GB/T 1711 resistance(35 d) peeling of coating

Embodiment 3

[0049] According to the formula ratio, 25 parts of antirust filler, 3 parts of defoamer, 3 parts of dispersant and 1 parts of thickener were added into 45 parts of waterborne epoxy emulsion, and the rotation speed was controlled at 2500+/?500 r/min, the emulsion was mixed and ground for 2 h, 2 part of titanium dioxide micro-nanocontainers was added and dispersed for 30 min, wherein defoaming agent was added in three times, grinding fineness was ?60 ?m, then the powder was filtered and packaged with a filter screen to obtain component A of the corrosion-resistant waterborne epoxy coating, containing titanium dioxide micro-nanocontainers;

[0050] 14 parts of waterborne epoxy curing agent and 7 parts of deionized water were mixed in proportion, and stirred at a high speed for 30 min to obtain component B of corrosion-resistant waterborne epoxy coating containing titanium dioxide micro-nano containers;

[0051] The component A was stirred and cured for 30 min, then mixed evenly with the component B in proportion, and coated on the surface of Q235 steel with a coating thickness of 100?5 ?m.

[0052] The performance test for the corrosion-resistant waterborne epoxy coating that contains micro-nanocontainers of the embodiment 3, and its cured coating. The test results were as follows in Table 2;

TABLE-US-00003 TABLE 2 Performance evaluation of the corrosion-resistant waterborne epoxy coating that contains micro-nanocontainers and its cured coating of embodiment 3. Test item Performance test Test standard State in Container After stirring evenly, Measuring by sight there are no lumps, and the mixture is uniform Coating appearance Earthly yellow Measuring by sight Surface drying time, h 3 GB/T 1728 Hard drying time, h 15 GB/T 1728 VOCs content, g/L 25.1 GB/T 23986 Applicable period 2.5 GB/T 31416 (normal temperature), h Film thickness, ?m 98 GB/T 13452.2 Bonding force with 8.2 GB/T 5210 substrate(Q235), MPa Hardness 3H GB/T 6739 shock resistance, cm 50 GB/T 1732 Neutral salt spray No blistering and GB/T 1711 resistance(35 d) peeling of coating

[0053] Performance evaluation of the corrosion-resistant waterborne epoxy coating that contains micro-nanocontainers and its cured coating of embodiment 3

Embodiment 4

[0054] According to the formula ratio, 18 parts of antirust filler; 3 parts of defoamer; 3 parts of dispersant and 2 parts of thickener were added into 42 parts of waterborne epoxy emulsion, and the rotation speed was controlled at 2500+/?500 r/min, the emulsion was mixed and ground for 2 h, 5 part of titanium dioxide micro-nanocontainers was added and dispersed for 30 min, wherein defoaming agent was added in three times, grinding fineness was ?60 ?m, then the powder was filtered and packaged with a filter screen to obtain component A of the corrosion-resistant waterborne epoxy coating, containing titanium dioxide micro-nanocontainers;

[0055] 13 parts of waterborne epoxy curing agent and 4 parts of deionized water were mixed in proportion, and stirred at a high speed for 30 min to obtain component B of corrosion-resistant waterborne epoxy coating containing titanium dioxide micro-nano containers;

[0056] The component A was stirred and cured for 30 min, then mixed evenly with the component B in proportion, and coated on the surface of Q235 steel with a coating thickness of 100?5 ?m.

[0057] The performance test for the corrosion-resistant waterborne epoxy coating that contains micro-nanocontainers of the embodiment 4, and its cured coating. The test results were as follows in Table 3;

[0058] Performance evaluation of the corrosion-resistant waterborne epoxy coating that contains micro-nanocontainers and its cured coating of embodiment 4

TABLE-US-00004 Test item Performance test Test standard State in Container After stirring evenly, Measuring by sight there are no lumps, and the mixture is uniform Coating appearance Earthly yellow Measuring by sight Surface drying time, h 1.5 GB/T 1728 Hard drying time, h 8 GB/T 1728 VOCs content, g/L 23.8 GB/T 23986 Applicable period 2 GB/T 31416 (normal temperature), h Film thickness, ?m 103 GB/T 13452.2 Bonding force with 7.5 GB/T 5210 substrate(Q235), MPa Hardness 3H GB/T 6739 shock resistance, cm 50 GB/T 1732 Neutral salt spray No blistering and GB/T 1711 resistance(35 d) peeling of coating

[0059] Scanning electron microscopy (SEM) was carried out on the titanium dioxide micro-nano spheres and titanium dioxide micro-nanocontainers prepared in Embodiment 1 of the present invention, and SEM images were obtained and illustrated in FIG. 1 and FIG. 2 were obtained, which showed the successful preparation of titanium dioxide microspheres, as well as the morphological changes of titanium dioxide micro-nanocontainers before and after layer by layer assembly, the flocculent substances on the surface are obtained by layer by layer assembly, and the assembly can well improve the compatibility between micro-nanocontainers and waterborne epoxy emulsion. FIG. 3 and FIG. 4 were the salt spray test photos of anti-corrosion waterborne epoxy coating on Q235 samples containing titanium dioxide micro-nano spheres and titanium dioxide micro-nanocontainers, respectively. It can be seen that the protection provided by titanium dioxide micro-nano spheres for the coating was very limited. After the salt spray test for 35 days, obvious corrosion and foaming phenomenon appeared, while the coating, containing titanium dioxide micro-nanocontainers, showed better salt spray resistance, molybdate inhibited the pitting corrosion of the coating well, and poly-dopamine, as a goalkeeper, controlled the slow and orderly release of corrosion inhibitors, thus enhancing the corrosion resistance and self-repairing ability of the coating, and providing better protection for the substrate.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the present invention, but not to limit it. Although the present invention has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that the technicians can still simplify, combine, modify or replace the specific embodiments of the present invention after reading the specification of this application, but these modifications or changes do not depart from the spirit and scope of the technical scheme of the present invention, and should be covered by the claims of the present invention.