Zinc-based composite fireproof coating and preparation method thereof

Abstract

The application discloses a zinc-based composite fireproof coating and a preparation method thereof, and belongs to the technical field of coatings. Resin mixture is obtained by mixing epoxy resin E51 and epoxy resin E20 at a weight ratio of 30-50:20-40; the zinc-based composite fireproof coating is prepared by mixing the resin mixture, a zinc-based compound, inorganic fillers, a dispersing agent, a defoaming agent and deionized water, and then adding a curing agent and stirring and mixing. The zinc-based composite fireproof coating is obtained by modifying zinc borate through phytic acid modification and zinc stearate hydrophobization, modifying the modified zinc borate by loading the modified zinc borate on halloysite, and multi-step functionalization design such as levodopa / copper ion chelation. The zinc-based composite fireproof coating realizes the synergistic effect of physical barrier effect, gas phase flame retardation and catalytic carbon formation. The structure promotes the rapid formation of a dense and expanded carbon layer in the initial stage of a fire, and significantly delays the heat transfer to a base material.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coatings, in particular to a zinc-based composite fireproof coating and a preparation method thereof. BACKGROUND

[0002] Epoxy resin is widely used in fireproof coatings in the fields of construction, shipbuilding, electronics, etc. due to its excellent adhesion, mechanical strength and chemical corrosion resistance. However, unmodified epoxy resin is highly flammable, decomposes rapidly and releases a large amount of heat and toxic smoke when on fire, and needs to be added with high-efficiency flame retardants to improve its fire safety. Zinc borate is an environmentally friendly inorganic flame retardant, which has become one of the important flame retardant additives in the epoxy resin system due to its low toxicity, smoke suppression and synergistic flame retardant effect. However, in the prior art, there are still some defects in the application of zinc borate in epoxy resin fireproof coatings.

[0003] Without surface modification, the surface of zinc borate particles has high polarity and poor compatibility with the hydrophobic epoxy resin matrix, and is prone to agglomeration during the preparation and curing of the coating. This agglomeration phenomenon leads to the formation of interface defects in the coating, not only reducing the mechanical properties of the coating, but also hindering the uniform release of the flame retardant components when on fire, affecting the stability and consistency of the flame retardant efficiency. In order to achieve the ideal flame retardant effect, the addition amount of zinc borate often needs to be increased, but high filling amount will exacerbate particle agglomeration, deteriorate the flexibility and interfacial adhesion of the coating, and cause the coating to easily crack or peel, reducing the integrity of the fireproof barrier in actual application. The prior art mostly uses simple compounding of zinc borate with other flame retardants (such as aluminum hydroxide, expanded graphite), and lacks functionalized synergistic design among the components. The key flame retardant mechanisms such as physical barrier, gas phase inhibition and catalytic char formation cannot be effectively coupled, limiting the improvement space of the overall efficiency of the flame retardant system, and it is difficult to achieve the requirement of ultra-fast formation of efficient heat insulation carbon layer in the early stage of fire.

[0004] Patent CN101880486A discloses an epoxy intumescent fireproof coating and a manufacturing method. The epoxy intumescent fireproof coating is prepared from low molecular weight bisphenol A type epoxy resin (polymerization degree < 2), bisphenol F type epoxy resin, saturated polyester resin, vinyl acrylate, organic and inorganic composite intumescent system, smoke suppressant, a small amount of additives, and a certain amount of temperature-resistant filler. The calcium epoxy intumescent fireproof coating has good water resistance, corrosion resistance and fire resistance, etc. However, the present application does not modify the flame retardant such as zinc borate, which may have poor compatibility between the flame retardant and the resin matrix, thereby affecting the physicochemical properties of the coating.

[0005] Therefore, it is an important problem to be solved in the field to design a zinc-based composite fireproof coating which has good fireproof performance and the formed coating also has good physicochemical properties. SUMMARY

[0006] To overcome the shortcomings of the prior art, the present invention provides a zinc-based composite fire-retardant coating and its preparation method. Specifically, the technical solution of the present invention includes the following:

[0007] A method for preparing a zinc-based composite fire-retardant coating, the method comprising the following steps:

[0008] Epoxy resin E51 and epoxy resin E20 are mixed in a weight ratio of 30~50:20~40 to obtain a resin mixture;

[0009] The zinc-based composite fireproof coating is prepared by mixing resin mixture, zinc-based composite, inorganic filler, dispersant, defoamer and deionized water, and then adding curing agent and stirring.

[0010] Furthermore, the preparation method of the zinc-based composite includes the following steps:

[0011] Zinc borate and phytic acid are mixed at a weight ratio of 10:1.3~1.7, and the pH is adjusted to 8.5~9 to react and obtain negatively charged zinc borate.

[0012] Modified zinc borate is obtained by mixing negatively charged zinc borate and zinc stearate in a weight ratio of 30-40:3-4.

[0013] Halloysite nanotubes were treated with oxalic acid to obtain modified halloysite;

[0014] Modified halloysite and modified zinc borate were mixed at a weight ratio of 1:8~10, ultrasonically dispersed, and then subjected to vacuum negative pressure treatment to obtain an intermediate.

[0015] The intermediate and levodopa were mixed and reacted at a weight ratio of 3-5:0.6-0.8 to obtain a complex;

[0016] The zinc-based complex was prepared by mixing the complex and copper sulfate in a weight ratio of 2-3:0.3-0.7.

[0017] Furthermore, the reaction conditions between zinc borate and phytic acid include a reaction temperature of 60-70°C and a reaction time of 2-4 hours.

[0018] Furthermore, the conditions for the mixed reaction of negatively charged zinc borate and zinc stearate include a reaction temperature of 85-95°C and a reaction time of 4-6 hours.

[0019] Furthermore, the oxalic acid is a 5 mol / L oxalic acid solution.

[0020] Furthermore, the oxalic acid treatment conditions include a treatment temperature of 60-75°C and a treatment time of 8-12 hours.

[0021] Furthermore, the conditions for ultrasonic dispersion include an ultrasonic power of 400-500W and an ultrasonic time of 30-50min.

[0022] Further, the vacuum negative pressure treatment condition includes pressure 0.1~0.15MPa and time 30~60min.

[0023] Further, the reaction condition of the intermediate and levodopa includes reaction temperature 23~25℃ and reaction time 12~24h.

[0024] Further, the reaction condition of the compound and copper sulfate includes reaction temperature 55~75℃ and reaction time 6~8h.

[0025] Further, the weight ratio of the resin mixture, zinc-based compound, inorganic filler, dispersant, defoaming agent, curing agent and deionized water is 50~60:6~8:4~7:1~3:0.5~1:1~3:20~40.

[0026] Further, the stirring condition of the resin mixture, zinc-based compound, inorganic filler, dispersant, defoaming agent, curing agent and deionized water includes stirring speed 1500~2000r / min and stirring time 30~50min.

[0027] Further, the inorganic filler is titanium white powder.

[0028] Further, the dispersant is BYK-220S.

[0029] Further, the defoaming agent is BYK-071.

[0030] Further, the curing agent includes one of 3-diethylaminopropylamine, phthalic anhydride or ethylenediamine.

[0031] Compared with the prior art, the beneficial effects of the present application are as follows:

[0032] (1) The modified zinc borate of the present application utilizes the phosphoric acid group in phytic acid to combine with zinc ions in zinc borate through coordination, replacing the original hydroxyl group, so that the surface has a stable negative charge; the carboxyl group of zinc stearate is bridged with phytic acid through zinc ions, and the long-chain alkyl group forms a hydrophobic barrier outward; the halloysite nanotube can enhance the lumen space and surface active groups after oxalic acid treatment, improve its ability to adsorb and load modified zinc borate and the ability to combine with levodopa; the modified zinc borate is loaded into the modified halloysite to obtain an intermediate in a vacuum negative pressure environment by using electrostatic adsorption and hydrophobic effect; the surface of the intermediate is coated with polydopamine formed by levodopa, and copper ions are fixed on the surface of the polydopamine by coordination to prepare a zinc-based composite; the modified zinc borate as the core flame-retardant component can dehydrate and absorb heat to reduce the temperature of the substrate under the action of high temperature or flame, and decompose to form a borate glass layer to isolate oxygen, and the phytic acid containing phosphorus element can also produce a certain flame-retardant effect; the modified halloysite has good heat resistance, effectively delaying the transfer of heat and combustible gas, and its tubular structure helps to support and enhance the carbon layer structure formed during combustion, and also provides a certain reinforcing effect when forming the coating; the polydopamine / copper on the surface of the composite can catalyze the resin matrix to form a more effective intumescent carbon layer during the combustion process, and synergistically retard flame.

[0033] (2) The present application modifies zinc borate by phytic acid modification and zinc stearate hydrophobization, and realizes the synergistic effect of physical barrier effect, gas phase flame retardant and catalytic charring through multi-step functionalization design such as modified halloysite loading modified zinc borate and levodopa / copper ion chelation. This structure helps to promote the rapid formation of a dense intumescent carbon layer, significantly delaying the transfer of heat to the substrate.

[0034] (3) In the present application, the zinc borate and halloysite nanotube are uniformly dispersed in the epoxy resin matrix after surface modification, vacuum negative pressure loading process and polydopamine / copper ion coating, avoiding the interface defects caused by agglomeration, which not only improves the physical and mechanical properties of the coating, but also ensures that the flame-retardant components can efficiently and consistently function when exposed to fire. DETAILED DESCRIPTION

[0035] The technical solutions of the present application will be clearly and completely described below through the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0036] Unless otherwise specified, the raw materials and reagents used in the present application below are commercially available or can be prepared by known methods.

[0037] Preparation Example 1:

[0038] The preparation method of the zinc-based complex includes the following steps:

[0039] 10 parts by weight of zinc borate were dispersed in 50 parts by weight of deionized water, 1.3 parts by weight of phytic acid were added, and the pH was adjusted to 8.5. The mixture was stirred at 60°C for 2 hours. After the reaction was completed, the mixture was centrifuged and washed three times with ethanol to obtain negatively charged zinc borate.

[0040] 30 parts by weight of negatively charged zinc borate and 3 parts by weight of zinc stearate were dispersed in 100 parts by weight of ethanol and stirred at 85°C for 4 hours. After the reaction was completed, the mixture was centrifuged and washed three times with ethanol. The mixture was then dried under vacuum at 60°C for 8 hours to obtain modified zinc borate.

[0041] Ten parts by weight of halloysite nanotubes were dispersed in 100 parts by weight of 5 mol / L oxalic acid solution and stirred at 60 °C for 8 h. After the reaction was completed, the mixture was centrifuged at 6000 r / min for 5 min and washed with deionized water until pH 7.4 to obtain modified halloysite.

[0042] One part by weight of modified halloysite and eight parts by weight of modified zinc borate were dispersed in 100 parts by weight of ethanol. After ultrasonic dispersion at 400W for 30 min, the mixture was subjected to vacuum negative pressure treatment under vacuum conditions of 0.1MPa for 30 min. The above vacuum negative pressure treatment was repeated three times to obtain a mixed solution. The modified zinc borate on the surface of the modified halloysite was washed with anhydrous ethanol, the precipitate was collected, dried at 40℃ for 12 h, and then ground to obtain an intermediate.

[0043] Three parts by weight of the intermediate were dispersed in 100 parts by weight of Tris-hydrochloric acid buffer at pH 8.5, and 0.6 parts by weight of levodopa were added. The mixture was stirred at 23°C for 12 h. After the reaction was completed, the mixture was centrifuged, washed, and then dried under vacuum to obtain the complex.

[0044] Two parts by weight of the complex were dispersed in 200 parts by weight of deionized water, and 0.3 parts by weight of copper sulfate were added. The mixture was stirred at 55°C for 6 hours. After the reaction was completed, the mixture was centrifuged, washed and vacuum dried to obtain the zinc-based complex.

[0045] Preparation Example 2:

[0046] The preparation method of the zinc-based complex includes the following steps:

[0047] 10 parts by weight of zinc borate were dispersed in 50 parts by weight of deionized water, 1.4 parts by weight of phytic acid were added, and the pH was adjusted to 8.6. The mixture was stirred at 62°C for 2.5 h. After the reaction was completed, the mixture was centrifuged and washed three times with ethanol to obtain negatively charged zinc borate.

[0048] 32 parts by weight of the negatively charged zinc borate and 3.2 parts by weight of zinc stearate were dispersed in 100 parts by weight of ethanol, and stirred at 87°C for 4.5 hours. After the reaction was completed, centrifugal separation was performed, and the product was washed with ethanol three times, and then vacuum dried at 65°C for 9 hours to obtain the modified zinc borate;

[0049] 10 parts by weight of halloysite nanotubes were dispersed in 100 parts by weight of 5 mol / L oxalic acid solution, and stirred at 62°C for 9 hours. After the reaction was completed, centrifugal separation was performed at a speed of 6000 r / min for 5 minutes, and then deionized water was used for washing until the pH was 7.4 to obtain the modified halloysite;

[0050] 1 part by weight of the modified halloysite and 8.5 parts by weight of the modified zinc borate were dispersed in 100 parts by weight of ethanol, and ultrasonic dispersion was performed at a power of 420 W for 35 minutes. Then, vacuum pressure holding treatment was performed at 0.11 MPa for 35 minutes. The above vacuum pressure holding treatment was repeated three times to obtain a mixed solution. The modified zinc borate on the surface of the modified halloysite was washed with anhydrous ethanol, and the precipitate was collected and ground after drying at 40°C for 12 hours to obtain an intermediate;

[0051] 3.5 parts by weight of the intermediate were dispersed in 100 parts by weight of Tris-hydrochloric acid buffer solution with a pH of 8.5, and 0.65 parts by weight of levodopa was added. Stirring reaction was performed at 24°C for 15 hours. After the reaction was completed, centrifugal washing was performed, and then vacuum drying was performed to obtain a complex;

[0052] 2.2 parts by weight of the complex were dispersed in 200 parts by weight of deionized water, and 0.4 parts by weight of copper sulfate was added. Stirring reaction was performed at 60°C for 6.5 hours. After the reaction was completed, centrifugal separation, washing, and vacuum drying were sequentially performed to obtain a zinc-based complex.

[0053] Preparation Example 3:

[0054] The preparation method of the zinc-based complex comprises the following steps:

[0055] 10 parts by weight of zinc borate were dispersed in 50 parts by weight of deionized water, 1.5 parts by weight of phytic acid was added, and the pH was adjusted to 8.7. Stirring reaction was performed at 64°C for 3 hours. After the reaction was completed, centrifugal separation was performed, and the product was washed with ethanol three times to obtain negatively charged zinc borate;

[0056] 35 parts by weight of the negatively charged zinc borate and 3.5 parts by weight of zinc stearate were dispersed in 100 parts by weight of ethanol, and stirred at 90°C for 5 hours. After the reaction was completed, centrifugal separation was performed, and the product was washed with ethanol three times, and then vacuum dried at 70°C for 10 hours to obtain the modified zinc borate;

[0057] 10 parts by weight of halloysite nanotubes were dispersed in 100 parts by weight of 5 mol / L oxalic acid solution, and stirred at 65°C for 10 hours. After the reaction was completed, centrifugal separation was performed at a speed of 6000 r / min for 5 minutes, and then deionized water was used for washing until the pH was 7.4 to obtain the modified halloysite;

[0058] 1 part by weight of modified halloysite and 9 parts by weight of modified zinc borate are dispersed in 100 parts by weight of ethanol, and after ultrasonic dispersion at a power of 450 W for 40 min, vacuum negative pressure treatment is carried out by pressure maintaining treatment at 0.12 MPa for 40 min. The above vacuum negative pressure treatment is repeated for 3 times to obtain a mixed solution. The modified zinc borate on the surface of the modified halloysite is washed with anhydrous ethanol, and the precipitate is collected and ground after drying at 40℃ for 12 h to obtain an intermediate;

[0059] 4 parts by weight of the intermediate are dispersed in 100 parts by weight of Tris-hydrochloric acid buffer solution with pH 8.5, and 0.7 parts by weight of levodopa is added. After stirring at 23℃ for 18 h, the reaction is completed, and the product is washed by centrifugation and vacuum drying to obtain a composite;

[0060] 2.5 parts by weight of the composite are dispersed in 200 parts by weight of deionized water, and 0.5 parts by weight of copper sulfate is added. After stirring at 65℃ for 7 h, the reaction is completed, and the product is washed by centrifugation, washing and vacuum drying to obtain a zinc-based composite.

[0061] Preparation Example 4:

[0062] The preparation method of the zinc-based composite comprises the following steps:

[0063] 10 parts by weight of zinc borate are dispersed in 50 parts by weight of deionized water, 1.6 parts by weight of phytic acid is added, and the pH is adjusted to 8.8. After stirring at 67℃ for 3.5 h, the reaction is completed, and the product is separated by centrifugation and washed with ethanol for 3 times to obtain negatively charged zinc borate;

[0064] 37 parts by weight of negatively charged zinc borate and 3.7 parts by weight of zinc stearate are dispersed in 100 parts by weight of ethanol, and the reaction is carried out by stirring at 92℃ for 5.5 h. After the reaction is completed, the product is separated by centrifugation and washed with ethanol for 3 times, and vacuum drying is carried out at 75℃ for 11 h to obtain modified zinc borate;

[0065] 10 parts by weight of halloysite nanotubes are dispersed in 100 parts by weight of 5 mol / L oxalic acid solution, and the reaction is carried out by stirring at 70℃ for 11 h. After the reaction is completed, the product is centrifuged at a speed of 6000 r / min for 5 min, and washed with deionized water to pH 7.4 to obtain modified halloysite;

[0066] 1 part by weight of modified halloysite and 9.5 parts by weight of modified zinc borate are dispersed in 100 parts by weight of ethanol, and after ultrasonic dispersion at a power of 470 W for 45 min, vacuum negative pressure treatment is carried out by pressure maintaining treatment at 0.14 MPa for 50 min. The above vacuum negative pressure treatment is repeated for 3 times to obtain a mixed solution. The modified zinc borate on the surface of the modified halloysite is washed with anhydrous ethanol, and the precipitate is collected and ground after drying at 40℃ for 12 h to obtain an intermediate;

[0067] 4.5 parts by weight of the intermediate were dispersed in 100 parts by weight of Tris-hydrochloric acid buffer at pH 8.5, 0.75 parts by weight of levodopa were added, and the reaction was stirred at 25°C for 21 h. After the reaction was completed, the product was centrifuged, washed, and vacuum dried to obtain a complex;

[0068] 2.7 parts by weight of the complex were dispersed in 200 parts by weight of deionized water, 0.6 parts by weight of copper sulfate were added, and the reaction was stirred at 70°C for 7.5 h. After the reaction was completed, the product was sequentially centrifuged, washed, and vacuum dried to obtain a zinc-based complex.

[0069] Preparation Example 5:

[0070] The method for preparing the zinc-based complex comprises the following steps:

[0071] 10 parts by weight of zinc borate were dispersed in 50 parts by weight of deionized water, 1.6 parts by weight of phytic acid were added, and the pH was adjusted to 9. The reaction was stirred at 70°C for 4 h. After the reaction was completed, the product was centrifuged and washed with ethanol three times to obtain negatively charged zinc borate;

[0072] 40 parts by weight of the negatively charged zinc borate and 4 parts by weight of zinc stearate were dispersed in 100 parts by weight of ethanol, and the reaction was stirred at 95°C for 6 h. After the reaction was completed, the product was centrifuged and washed with ethanol three times, and vacuum dried at 80°C for 12 h to obtain modified zinc borate;

[0073] 10 parts by weight of halloysite nanotubes were dispersed in 100 parts by weight of 5 mol / L oxalic acid solution, and the reaction was stirred at 75°C for 12 h. After the reaction was completed, the product was centrifuged at a speed of 6000 r / min for 5 min and washed with deionized water until the pH was 7.4 to obtain modified halloysite;

[0074] 1 part by weight of the modified halloysite and 10 parts by weight of the modified zinc borate were dispersed in 100 parts by weight of ethanol, and ultrasonic dispersion was performed at a power of 500 W for 50 min. Then, vacuum pressure treatment was performed at 0.15 MPa for 60 min. The above vacuum pressure treatment was repeated three times to obtain a mixed solution. The modified zinc borate on the surface of the modified halloysite was washed with anhydrous ethanol, the precipitate was collected, and the product was ground after drying at 40°C for 12 h to obtain an intermediate;

[0075] 5 parts by weight of the intermediate were dispersed in 100 parts by weight of Tris-hydrochloric acid buffer at pH 8.5, 0.8 parts by weight of levodopa were added, and the reaction was stirred at 25°C for 24 h. After the reaction was completed, the product was centrifuged, washed, and vacuum dried to obtain a complex;

[0076] 3 parts by weight of the complex were dispersed in 200 parts by weight of deionized water, 0.7 parts by weight of copper sulfate were added, and the reaction was stirred at 75°C for 8 h. After the reaction was completed, the product was sequentially centrifuged, washed, and vacuum dried to obtain a zinc-based complex.

[0077] Preparation Example 6:

[0078] The preparation method of the zinc-based complex includes the following steps:

[0079] 10 parts by weight of halloysite nanotubes are dispersed in 100 parts by weight of a 5 mol / L oxalic acid solution, and stirred at 75°C for 12 h. After the reaction is completed, centrifugation is performed at a speed of 6000 r / min for 5 min, and washing is performed with deionized water until the pH is 7.4 to obtain modified halloysite;

[0080] 1 part by weight of modified halloysite and 10 parts by weight of zinc borate are dispersed in 100 parts by weight of ethanol, and ultrasonic dispersion is performed at a power of 500 W for 50 min. Then, vacuum pressure treatment is performed at a vacuum condition of 0.15 MPa for 60 min. The above vacuum pressure treatment is repeated for 3 times to obtain a mixed solution. The modified zinc borate on the surface of the modified halloysite is washed with anhydrous ethanol, and the precipitate is collected. After drying at 40°C for 12 h, grinding is performed to obtain an intermediate;

[0081] 5 parts by weight of the intermediate are dispersed in 100 parts by weight of a Tris-hydrochloric acid buffer solution with a pH of 8.5, and 0.8 parts by weight of levodopa is added. Stirring reaction is performed at 25°C for 24 h. After the reaction is completed, centrifugation, washing, and vacuum drying are sequentially performed to obtain a complex;

[0082] 3 parts by weight of the complex are dispersed in 200 parts by weight of deionized water, and 0.7 parts by weight of copper sulfate is added. Stirring reaction is performed at 75°C for 8 h. After the reaction is completed, centrifugation, washing, and vacuum drying are sequentially performed to obtain a zinc-based complex.

[0083] Preparation Example 7:

[0084] The preparation method of the zinc-based complex includes the following steps:

[0085] 10 parts by weight of zinc borate are dispersed in 50 parts by weight of deionized water, 1.6 parts by weight of phytic acid is added, and the pH is adjusted to 9. Stirring reaction is performed at 70°C for 4 h. After the reaction is completed, centrifugal separation is performed, and washing is performed with ethanol for 3 times to obtain negatively charged zinc borate;

[0086] 10 parts by weight of halloysite nanotubes are dispersed in 100 parts by weight of a 5 mol / L oxalic acid solution, and stirred at 75°C for 12 h. After the reaction is completed, centrifugation is performed at a speed of 6000 r / min for 5 min, and washing is performed with deionized water until the pH is 7.4 to obtain modified halloysite;

[0087] 1 part by weight of modified halloysite and 10 parts by weight of negatively charged zinc borate are dispersed in 100 parts by weight of ethanol, ultrasonic dispersion is carried out at a power of 500 W for 50 min, vacuum pressure holding treatment is carried out at a vacuum condition of 0.15 MPa for 60 min, the above vacuum pressure holding treatment is repeated for 3 times to obtain a mixed solution, the modified zinc borate on the surface of the modified halloysite is washed with anhydrous ethanol, the precipitate is collected, and the intermediate is obtained by grinding after drying at 40℃ for 12 h;

[0088] 5 parts by weight of the intermediate are dispersed in 100 parts by weight of Tris-hydrochloric acid buffer solution with pH 8.5, 0.8 part by weight of levodopa is added, stirring reaction is carried out at 25℃ for 24 h, centrifugal washing is carried out after the reaction is completed, and the composite is obtained by vacuum drying.

[0089] 3 parts by weight of the composite are dispersed in 200 parts by weight of deionized water, 0.7 part by weight of copper sulfate is added, stirring reaction is carried out at 75℃ for 8 h, and the zinc-based composite is obtained by centrifugal washing, washing and vacuum drying in sequence after the reaction is completed.

[0090] Preparation Example 8:

[0091] The preparation method of the zinc-based composite comprises the following steps:

[0092] 0.5 part by weight of octadecyltrimethoxysilane is dispersed in 50 parts by weight of isopropyl alcohol, 20 parts by weight of zinc borate is further added, stirring reaction is carried out at 65℃ for 8 h, the reaction is cooled to 25℃ after the reaction is completed, and the modified zinc borate is obtained by filtration, washing and drying in sequence.

[0093] 10 parts by weight of halloysite nanotubes are dispersed in 100 parts by weight of 5 mol / L oxalic acid solution, stirring reaction is carried out at 75℃ for 12 h, the reaction is centrifuged at a speed of 6000 r / min for 5 min after the reaction is completed, and the modified halloysite is obtained by washing with deionized water until pH 7.4.

[0094] 1 part by weight of modified halloysite and 10 parts by weight of modified zinc borate are dispersed in 100 parts by weight of ethanol, ultrasonic dispersion is carried out at a power of 500 W for 50 min, vacuum pressure holding treatment is carried out at a vacuum condition of 0.15 MPa for 60 min, the above vacuum pressure holding treatment is repeated for 3 times to obtain a mixed solution, the modified zinc borate on the surface of the modified halloysite is washed with anhydrous ethanol, the precipitate is collected, and the intermediate is obtained by grinding after drying at 40℃ for 12 h;

[0095] 5 parts by weight of the intermediate are dispersed in 100 parts by weight of Tris-hydrochloric acid buffer solution with pH 8.5, 0.8 part by weight of levodopa is added, stirring reaction is carried out at 25℃ for 24 h, centrifugal washing is carried out after the reaction is completed, and the composite is obtained by vacuum drying.

[0096] 3 parts by weight of the composite were dispersed in 200 parts by weight of deionized water, 0.7 parts by weight of copper sulfate was added, and the reaction was stirred at 75°C for 8h. After the reaction was completed, the zinc-based composite was prepared by centrifugation, washing, and vacuum drying in sequence.

[0097] Preparation Example 9:

[0098] The method for preparing the zinc-based composite comprises the following steps:

[0099] 10 parts by weight of zinc borate were dispersed in 50 parts by weight of deionized water, 1.6 parts by weight of phytic acid was added, and the pH was adjusted to 9. The reaction was stirred at 70°C for 4h. After the reaction was completed, the negatively charged zinc borate was obtained by centrifugal separation and washing with ethanol for 3 times;

[0100] 40 parts by weight of the negatively charged zinc borate and 4 parts by weight of zinc stearate were dispersed in 100 parts by weight of ethanol, and the reaction was stirred at 95°C for 6h. After the reaction was completed, the modified zinc borate was obtained by centrifugal separation, washing with ethanol for 3 times, and vacuum drying at 80°C for 12h;

[0101] 10 parts by weight of halloysite nanotubes were dispersed in 100 parts by weight of 5mol / L oxalic acid solution, and the reaction was stirred at 75°C for 12h. After the reaction was completed, the modified halloysite was obtained by centrifugal separation at a speed of 6000r / min for 5min and washing with deionized water until the pH was 7.4;

[0102] 1 part by weight of the modified halloysite and 10 parts by weight of the modified zinc borate were dispersed in 100 parts by weight of ethanol, and ultrasonic dispersion was performed at a power of 500W for 50min. Then, vacuum negative pressure treatment was performed by pressure holding treatment at 0.15MPa for 60min. The above vacuum negative pressure treatment was repeated for 3 times to obtain a mixed solution. The modified zinc borate on the surface of the modified halloysite was washed with anhydrous ethanol, the precipitate was collected, and the zinc-based composite was prepared by drying at 40°C for 12h.

[0103] Preparation Example 10:

[0104] The method for preparing the zinc-based composite comprises the following steps:

[0105] 10 parts by weight of zinc borate were dispersed in 50 parts by weight of deionized water, 1.6 parts by weight of phytic acid was added, and the pH was adjusted to 9. The reaction was stirred at 70°C for 4h. After the reaction was completed, the negatively charged zinc borate was obtained by centrifugal separation and washing with ethanol for 3 times;

[0106] 40 parts by weight of the negatively charged zinc borate and 4 parts by weight of zinc stearate were dispersed in 100 parts by weight of ethanol, and the reaction was stirred at 95°C for 6h. After the reaction was completed, the modified zinc borate was obtained by centrifugal separation, washing with ethanol for 3 times, and vacuum drying at 80°C for 12h;

[0107] 10 parts by weight of halloysite nanotubes were dispersed in 100 parts by weight of 5 mol / L oxalic acid solution, and stirred at 75°C for 12 h. After the reaction, centrifugation was performed at a speed of 6000 r / min for 5 min, and deionized water was used for washing until pH 7.4 to obtain modified halloysite;

[0108] 1 part by weight of modified halloysite and 10 parts by weight of modified zinc borate were dispersed in 100 parts by weight of ethanol, and ultrasonic dispersion was performed at a power of 500 W for 50 min. Then, vacuum pressure treatment was performed at 0.15 MPa for 60 min. The above vacuum pressure treatment was repeated for 3 times to obtain a mixed solution. The modified zinc borate on the surface of the modified halloysite was washed with anhydrous ethanol, and the precipitate was collected and ground after drying at 40°C for 12 h to obtain an intermediate.

[0109] 5 parts by weight of the intermediate were dispersed in 100 parts by weight of Tris-hydrochloric acid buffer solution with pH 8.5, and 0.8 parts by weight of levodopa was added. Stirring reaction was performed at 25°C for 24 h. After the reaction, centrifugation and vacuum drying were performed to obtain a zinc-based composite.

[0110] Example 1:

[0111] A preparation method of a zinc-based composite fireproof coating includes the following steps:

[0112] 30 parts by weight of epoxy resin E51 and 20 parts by weight of epoxy resin E20 were mixed at a speed of 600 r / min at 50°C for 20 min to obtain an epoxy resin mixture. 50 parts by weight of the epoxy resin mixture, 6 parts by weight of the zinc-based composite prepared in Preparation Example 1, 4 parts by weight of titanium white, 1 part by weight of BYK-220S, 0.5 part by weight of BYK-071 and 20 parts by weight of deionized water were mixed and dispersed at a speed of 1500 r / min at 40°C for 40 min. Then, 1 part by weight of 3-diethylaminopropylamine was added, and the stirring and dispersion were continued for 30 min to obtain a zinc-based composite fireproof coating.

[0113] Example 2:

[0114] A preparation method of a zinc-based composite fireproof coating includes the following steps:

[0115] 35 parts by weight of epoxy resin E51 and 25 parts by weight of epoxy resin E20 were mixed at a speed of 650 r / min at 52°C for 22 min to obtain an epoxy resin mixture. 52 parts by weight of the epoxy resin mixture, 6.5 parts by weight of the zinc-based composite prepared in Preparation Example 2, 4.5 parts by weight of titanium white, 1.5 parts by weight of BYK-220S, 0.6 parts by weight of BYK-071 and 25 parts by weight of deionized water were mixed and dispersed at a speed of 1600 r / min at 42°C for 45 min. Then, 1.5 parts by weight of phthalic anhydride was added, and the stirring and dispersion were continued for 35 min to obtain a zinc-based composite fireproof coating.

[0116] Example 3:

[0117] A preparation method of a zinc-based composite fireproof coating comprises the following steps:

[0118] 40 parts by weight of epoxy resin E51 and 30 parts by weight of epoxy resin E20 are mixed at 55°C at a stirring speed of 700 r / min for 25 min to obtain an epoxy resin mixture; 55 parts by weight of the epoxy resin mixture, 7 parts by weight of the zinc-based composite prepared in Preparation Example 3, 5 parts by weight of titanium white, 2 parts by weight of BYK-220S, 0.7 parts by weight of BYK-071 and 30 parts by weight of deionized water are mixed and dispersed at 45°C at a stirring speed of 1700 r / min for 50 min, 2 parts by weight of ethylenediamine is further added and dispersed for 40 min to obtain a zinc-based composite fireproof coating.

[0119] Example 4:

[0120] A preparation method of a zinc-based composite fireproof coating comprises the following steps:

[0121] 45 parts by weight of epoxy resin E51 and 35 parts by weight of epoxy resin E20 are mixed at 57°C at a stirring speed of 750 r / min for 27 min to obtain an epoxy resin mixture; 57 parts by weight of the epoxy resin mixture, 7.5 parts by weight of the zinc-based composite prepared in Preparation Example 4, 6 parts by weight of titanium white, 2.5 parts by weight of BYK-220S, 0.8 parts by weight of BYK-071 and 35 parts by weight of deionized water are mixed and dispersed at 47°C at a stirring speed of 1800 r / min for 55 min, 2.5 parts by weight of ethylenediamine is further added and dispersed for 45 min to obtain a zinc-based composite fireproof coating.

[0122] Example 5:

[0123] A preparation method of a zinc-based composite fireproof coating comprises the following steps:

[0124] 50 parts by weight of epoxy resin E51 and 40 parts by weight of epoxy resin E20 are mixed at 60°C at a stirring speed of 800 r / min for 30 min to obtain an epoxy resin mixture; 60 parts by weight of the epoxy resin mixture, 8 parts by weight of the zinc-based composite prepared in Preparation Example 5, 7 parts by weight of titanium white, 3 parts by weight of BYK-220S, 1 part by weight of BYK-071 and 40 parts by weight of deionized water are mixed and dispersed at 50°C at a stirring speed of 2000 r / min for 60 min, 3 parts by weight of ethylenediamine is further added and dispersed for 50 min to obtain a zinc-based composite fireproof coating.

[0125] Comparative Example 1:

[0126] A preparation method of a zinc-based composite fireproof coating comprises the following steps:

[0127] The zinc-based composite prepared in Preparation Example 5 in Example 5 was replaced with the zinc-based composite prepared in Preparation Example 6, and the other operations were consistent with Example 5.

[0128] Comparative Example 2:

[0129] A method for preparing a zinc-based composite fireproof coating includes the following steps:

[0130] The zinc-based composite prepared in Preparation Example 5 in Example 5 was replaced with the zinc-based composite prepared in Preparation Example 7, and the other operations were consistent with Example 5.

[0131] Comparative Example 3:

[0132] A method for preparing a zinc-based composite fireproof coating includes the following steps:

[0133] The zinc-based composite prepared in Preparation Example 5 in Example 5 was replaced with the zinc-based composite prepared in Preparation Example 8, and the other operations were consistent with Example 5.

[0134] Comparative Example 4:

[0135] A method for preparing a zinc-based composite fireproof coating includes the following steps:

[0136] The zinc-based composite prepared in Preparation Example 5 in Example 5 was replaced with the zinc-based composite prepared in Preparation Example 9, and the other operations were consistent with Example 5.

[0137] Comparative Example 5:

[0138] A method for preparing a zinc-based composite fireproof coating includes the following steps:

[0139] The zinc-based composite prepared in Preparation Example 5 in Example 5 was replaced with the zinc-based composite prepared in Preparation Example 10, and the other operations were consistent with Example 5.

[0140] Comparative Example 6:

[0141] A method for preparing a zinc-based composite fireproof coating includes the following steps:

[0142] The zinc-based composite prepared in Preparation Example 5 in Example 5 was replaced with 4 parts by weight of zinc borate and 4 parts by weight of halloysite nanotubes, and the other operations were consistent with Example 5.

[0143] Test Example 1:

[0144] The zinc-based composite fireproof coatings prepared in Examples 1-5 and Comparative Examples 1-6 were coated on a steel plate with a size of 150 mm x 70 mm x 0.5 mm, and the coating thickness was controlled to be 2±0.2 mm. The zinc-based composite fireproof coating was cured at 200°C for 15 min to obtain a zinc-based composite fireproof coating layer, and the fireproof performance of the zinc-based composite fireproof coating layer was tested.

[0145] The fireproof coating is vertically faced to the testing device and fixed, and a K-type thermocouple is attached to the back of the sample plate along the path of flame burning. Among them, the distance between the sample plate and the flame device port is the outer flame distance of the flame, the outer flame of the flame directly contacts the coating, and the position of the thermocouple corresponds to the flame burning point, and the interval is not more than 5 mm. After burning, the timing starts, the test time is 30 min, and the temperature function recorder records the back plate temperature of the sample plate every 2 s. If the coating falls off, burns through or other phenomena in the flame, the test is ended in advance, and the test results are shown in Table 1.

[0146]

[0147] It can be known from the test results in Table 1 that the zinc-based composite fireproof coating prepared in Examples 1-5 of the present application has good fireproof performance by reducing the back plate temperature, improving the expansion ratio and enhancing the flame impact stability. The reason for the reduced fireproof performance of Comparative Example 1 may be that the zinc borate has no negative charge on the surface and cannot be effectively loaded into the modified halloysite by electrostatic adsorption, the hydrophobic modification of zinc stearate is lacking, the interface compatibility of zinc borate and modified halloysite is poor, the dispersion of zinc-based composite in the resin matrix is poor, and the fireproof performance is reduced, thereby affecting the fireproof performance of the zinc-based composite fireproof coating; the reason for the reduced fireproof performance of Comparative Example 2 may be that the negatively charged zinc borate can be loaded into the modified halloysite by electrostatic adsorption, but the hydrophobic modification of zinc stearate is lacking, which is easy to fall off in the washing step, thereby affecting the loading amount and reducing the effective content of the zinc-based composite, thereby affecting the fireproof performance of the zinc-based composite fireproof coating; the reason for the reduced fireproof performance of Comparative Example 3 may be that the hydrophobic modification of zinc borate can partially improve the loading stability, but the effect of electrostatic adsorption is lacking, the loading efficiency is still affected, and the effective content of the zinc-based composite is reduced, thereby affecting the fireproof performance of the zinc-based composite fireproof coating; the reason for the reduced fireproof performance of Comparative Example 4 may be the lack of polydopamine and copper ions, polydopamine can provide adhesion, and copper ions can catalyze the densification of the carbon layer, and the lack of the above two substances in the zinc-based composite leads to low carbon layer expansion efficiency and poor heat insulation; the reason for the reduced fireproof performance of Comparative Example 5 may be that although the surface has polydopamine to improve the interfacial bonding strength, the catalytic carbonization effect of copper ions is lacking, and the carbon layer expansion rate and stability are insufficient; the reason for the reduced fireproof performance of Comparative Example 6 may be that the zinc borate and halloysite nanotubes are directly physically mixed with the resin matrix, the dispersion of the two is poor, and agglomeration is easy, which cannot form a synergistic effect, thereby leading to the reduced fireproof performance of the zinc-based composite fireproof coating.

[0148] Test Example 2: Physicochemical property test of coating

[0149] The zinc-based composite fireproof coating prepared in Examples 1-5 and Comparative Examples 4-6 was coated on a steel plate with a size of 150 mm x 70 mm x 0.5 mm, the coating thickness was controlled to be 2±0.2 mm, and the zinc-based composite fireproof coating layer was obtained by curing treatment at 200℃ for 15 min, and the physicochemical properties of the zinc-based composite fireproof coating were tested.

[0150] Impact resistance: the impact resistance of the zinc-based composite fireproof coating layer was tested according to the method in GB / T732-93;

[0151] Adhesion test: the adhesion of the zinc-based composite fireproof coating layer was tested according to the method in GB / T9286-1998; the test results are shown in Table 2.

[0152]

[0153] It can be observed from the data in Table 2 that the zinc-based composite fireproof coating prepared in Examples 1-5 has good impact resistance and adhesion, while the physicochemical properties of the zinc-based composite fireproof coating prepared in Comparative Examples 4-6 are reduced to different degrees. The performance reduction of Comparative Example 4 may be that the polydopamine layer formed by levodopa can enhance the bonding force between the zinc-based composite and the resin matrix, and copper ions can help to improve the crosslinking density, while the preparation of the zinc-based composite in Comparative Example 4 lacks this step, resulting in poor compatibility with the resin matrix, thereby affecting the physicochemical properties of the zinc-based composite fireproof material; the performance reduction of Comparative Example 5 may be that the chelation of copper ions with polydopamine can form a dense protective layer to improve the interfacial strength, and the lack of copper crosslinking makes the coating prone to cracking under impact; the performance reduction of Comparative Example 6 may be that the zinc borate is not encapsulated in the halloysite nanotubes and is directly exposed in the resin matrix, which has poor dispersibility and is prone to agglomeration, resulting in a decrease in the density of the zinc-based composite fireproof coating and deterioration of the impact resistance and adhesion.

[0154] The above examples have described the technical solutions and beneficial effects of the present application in detail, and it should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application.

Claims

1. A method for preparing a zinc-based composite fireproof coating, characterized in that, The preparation method comprises the following steps: The epoxy resin E51 and the epoxy resin E20 are mixed in a weight ratio of 30-50:20-40 to obtain a resin mixture; The resin mixture, the zinc-based composite, the inorganic filler, the dispersant, the defoaming agent and deionized water are mixed, and then a curing agent is added and stirred to obtain the zinc-based composite fireproof coating; The preparation method of the zinc-based composite comprises the following steps: The zinc borate and the phytic acid are mixed in a weight ratio of 10:1.3-1.7, and the pH is adjusted to 8.5-9 to obtain negatively charged zinc borate; The negatively charged zinc borate and the zinc stearate are mixed in a weight ratio of 30-40:3-4 to obtain modified zinc borate; The halloysite nanotubes are treated with oxalic acid to obtain modified halloysite; The modified halloysite and the modified zinc borate are mixed in a weight ratio of 1:8-10, and then ultrasonic dispersion is performed, and then vacuum negative pressure treatment is performed to obtain an intermediate; The intermediate and levodopa are mixed in a weight ratio of 3-5:0.6-0.8 to obtain a composite; The composite and copper sulfate are mixed in a weight ratio of 2-3:0.3-0.7 to obtain the zinc-based composite. The oxalic acid is a 5 mol / L oxalic acid solution.

2. The method of claim 1, wherein the zinc-based composite fireproof paint is prepared by mixing zinc powder, a binder, a solvent, and a dispersant. The weight ratio of the resin mixture, the zinc-based composite, the inorganic filler, the dispersant, the defoaming agent, the curing agent and deionized water is 50-60:6-8:4-7:1-3:0.5-1:1-3:20-40.

3. The preparation method of the zinc-based composite fire-retardant coating as described in claim 1, characterized in that, The stirring conditions of the resin mixture, the zinc-based composite, the inorganic filler, the dispersant, the defoaming agent, the curing agent and deionized water comprise a stirring speed of 1500-2000 r / min and a stirring time of 30-50 min.

4. The preparation method of the zinc-based composite fire-retardant coating as described in claim 1, characterized in that, The inorganic filler is titanium white.

5. The preparation method of the zinc-based composite fire-retardant coating as described in claim 1, characterized in that, The dispersant is BYK-220S.

6. The method of preparing zinc-based composite fireproof paint according to claim 1, wherein the zinc-based composite fireproof paint is prepared by adding 0.1 to 0.5 parts by weight of the zinc-based composite fireproof paint of claim 1 to 100 parts by weight of a base paint. The defoaming agent is a defoaming agent BYK-071.

7. The preparation method of the zinc-based composite fire-retardant coating as described in claim 1, characterized in that, The curing agent comprises one of diethylaminopropylamine, phthalic anhydride or ethylenediamine.

8. A zinc-based composite fireproofing coating, characterized by, The zinc-based composite fireproof coating is prepared by the preparation method of any one of claims 1-7.

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