Preparation method of environment-friendly CN@GO@LAA@Cu intumescent fire-retardant coating

Abstract

The application discloses a preparation method of an environment-friendly CN@GO@LAA@Cu intumescent fireproof coating, and the preparation method comprises the following steps: (1) preparing a base material; (2) preparing a CN@GO hybrid material; (3) preparing a CN@GO@LAA hybrid material, (3) preparing a CN@GO@LAA@Cu hybrid material; and (4) preparing the environment-friendly CN@GO@LAA@Cu intumescent fireproof coating. The modified CN@GO@LAA@Cu nano hybrid material is combined with the water-based intumescent fireproof coating, potential dangerous characteristics of the current water-based fireproof coating, such as low carbon layer strength, uneven intumescence and poor fireproof performance, are solved, and the obtained water-based intumescent fireproof coating can form a uniform and dense intumescent carbon layer at high temperature, thereby achieving a good protection effect. The application is mainly used for steel structure fire protection, prolongs the time for the steel structure to reach a failure temperature and collapse under a fire, and thus valuable rescue time is obtained for fire fighting. The water-based intumescent fireproof coating has raw materials which are easy to obtain, simple preparation, low cost, water-based and environment-friendly, and has wide industrial application value.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of preparation methods of epoxy composite coatings, and particularly relates to a preparation method and application of an environmentally-friendly CN@GO@LAA@Cu intumescent fireproof coating. BACKGROUND

[0002] In the construction industry, steel structures are widely used due to their excellent properties. Although steel structures are not flammable, their mechanical properties will decrease sharply with the increase of temperature. When the temperature of steel exceeds 500℃, the bare steel structure will collapse within 15 minutes due to mechanical property failure. Therefore, in order to meet the increasingly stringent fire safety and environmental protection requirements, water-based intumescent fireproof coatings are usually applied on the surface of steel structures to protect the steel structures. Water-based intumescent fireproof coatings are usually composed of film-forming substances, acid sources, carbon sources and gas sources, with water as the solvent. In the event of a fire, they will interact to form a honeycomb-like porous expanded carbon layer. This expanded carbon layer can effectively block the transfer of heat and flammable gases, thereby delaying the temperature rise of the steel structure and gaining valuable rescue and escape time. However, water-based intumescent fireproof coatings still have defects such as uneven expansion, low carbon layer strength and poor oxidation resistance. Adding inorganic fillers to the intumescent system can improve these defects of the expanded carbon layer, affect its expansion behavior and foam structure, and effectively improve the expansion and carbon layer strength of the fireproof coating, thereby enhancing the fireproof performance. Graphitic carbon nitride (CN) and graphene oxide (GO) have great specific surface area and good physical barrier properties as two-dimensional nanomaterials, and have great potential as flame retardants. Therefore, we designed a simple and green self-assembly method to prepare an environmentally-friendly fireproof coating based on graphitic carbon nitride and graphene oxide. L-ascorbic acid and Cu 2+ two functional molecules and ions enhance the flame retardancy of the two-dimensional / two-dimensional network of graphitic carbon nitride and graphene oxide. Here, graphitic carbon nitride and graphene oxide can act as a flame-retardant barrier to block heat and volatile substances; L-ascorbic acid has reducing properties and can promote the thermal reduction of graphene oxide to form reduced graphene oxide with higher thermal stability, further adsorbing and capturing volatile substances; Cu 2+ can form CuO and Cu2O as active catalytic sites at high temperatures to promote carbonization and redox reactions of decomposition products and accelerate the formation of an expanded carbon layer. The synergistic effect of the environmentally-friendly flame retardants CN@GO@LAA@Cu between the components is used to improve the expansion and carbon layer strength of the water-based intumescent fireproof coating, thereby enhancing the fireproof performance of the water-based intumescent fireproof coating. SUMMARY

[0003] The application provides a preparation method of an environment-friendly CN@GO@LAA@Cu intumescent fireproof coating and expands the application of the CN@GO@LAA@Cu flame retardant in the field of fireproof coatings.

[0004] To achieve the above technical purposes, the application adopts the following technical scheme:

[0005] The preparation method of the environment-friendly CN@GO@LAA@Cu intumescent fireproof coating has the characteristics that the preparation includes the following steps:

[0006] S1: Preparation of a base material: a certain amount of water-based epoxy resin, a curing agent, melamine polyphosphate, dipentaerythritol and melamine are weighed, stirred at a speed of 300 r / min for 3 h, and then stirred at a speed of 60 r / min for 2 h to obtain a uniformly mixed base material;

[0007] S2: Preparation of a CN@GO hybrid material: a certain amount of graphite carbon nitride is dispersed into 100 mL of a graphene oxide solution (0.5 mg·mL -1 ) and then ultrasonically treated for 30 min, and then stirred with a magnetic stirrer for 12 h, and then the product is filtered, washed and dried at 60 DEG C for 12 h to obtain the CN@GO hybrid material;

[0008] S3: Preparation of a CN@GO@LAA hybrid material: a certain amount of CN@GO is ultrasonically dispersed in deionized water, and then a certain amount of L-ascorbic acid is added and stirred with a magnetic stirrer for 1 h, and then the product is centrifuged and washed to obtain the CN@GO@LAA hybrid material;

[0009] S4: Preparation of a CN@GO@LAA@Cu hybrid material: a certain amount of CN@GO@LAA is ultrasonically dispersed in 100 mL of water, and then a certain amount of copper acetate is added and stirred with a magnetic stirrer for 2 h, and then the product is centrifuged and washed to obtain the CN@GO@LAA@Cu hybrid material;

[0010] S5: Preparation of the environment-friendly CN@GO@LAA@Cu intumescent fireproof coating: a certain amount of the base material and a certain amount of the CN@GO@LAA@Cu hybrid material are mixed, a uniformly dispersed system is formed by mechanical stirring for 5 h, and then the uniformly dispersed system is brushed on the surface of a steel sheet, and after brushing, the environment-friendly CN@GO@LAA@Cu intumescent fireproof coating is obtained after curing at room temperature for 7 days.

[0011] Further, in step S1, the mass ratio of the melamine polyphosphate, the dipentaerythritol and the melamine is 6:3:1.

[0012] Further, the mass ratio of the graphite phase carbon nitride and graphene oxide in step S2 is 1-2:1;

[0013] Further, the mass ratio of the CN@GO and L-ascorbic acid in step S3 is 1-1.5:1;

[0014] Further, the mass ratio of the CN@GO@LAA and copper acetate in step S4 is 1:35-45;

[0015] Further, the mass ratio of the CN@GO@LAA@Cu hybrid material in step S5 accounts for 2%-6% of the total mass of the uniform dispersion system.

[0016] Beneficial effects:

[0017] Compared with the prior art, the present application has the following beneficial effects:

[0018] The preparation method of the environment-friendly CN@GO@LAA@Cu intumescent fireproof coating provided by the present application solves the potential dangerous characteristics of low carbon layer strength, uneven expansion and poor fireproof performance of the current water-based fireproof coating, and the obtained water-based intumescent fireproof coating can form a uniform and dense expanded carbon layer at high temperature, block the heat transfer to the steel structure, and play a good protective role. The present application is mainly used for steel structure fire protection, prolongs the time for the steel structure to reach the failure temperature under fire, so as to gain valuable rescue time for fire fighting. The water-based intumescent fireproof coating has easy-to-obtain raw materials, simple preparation, low cost, water-based environmental protection, and has wide industrial application value. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The transmission electron micrographs of CN, CN@GO, CN@GO@LAA and CN@GO@LAA@Cu and the element mapping of CN@GO@LAA@Cu, wherein A and E are CN, B and F are CN@GO, C and G are CN@GO@LAA, D and H are CN@GO@LAA@Cu; I, J, K and L are respectively the C, N, O and Cu element mapping results of CN@GO@LAA@Cu.

[0020] Figure 2 The scanning electron micrographs of the cross section of EP, CN / EP, CN@GO / EP, CN@GO@LAA / EP and CN@GO@LAA@Cu / EP coating, wherein A is EP, B is CN / EP, C is CN@GO / EP, D is CN@GO@LAA / EP, and E is CN@GO@LAA@Cu / EP.

[0021] Figure 3 The curve of the temperature change of the back surface of the steel plate with time after the large plate method test.

[0022] Figure 4 Digital photos of the expanded carbon layer after the furnace test, wherein A is EP, B is CN / EP, C is CN@GO / EP, D is CN@GO@LAA / EP, and E is CN@GO@LAA@Cu / EP.

[0023] Figure 5 Scanning electron microscope photos of the carbon layer after the large plate test, wherein A is EP, B is CN / EP, C is CN@GO / EP, D is CN@GO@LAA / EP, and E is CN@GO@LAA@Cu / EP. DETAILED DESCRIPTION

[0024] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not used to limit the present application.

[0025] Embodiment:

[0026] A preparation method of an environmentally friendly CN@GO@LAA@Cu expanded fireproof coating, the specific preparation comprising the following steps:

[0027] S1: Preparation of the base material: weigh 50 g of water-based epoxy resin, 25 g of curing agent, 15 g of melamine polyphosphate, 7.5 g of dipentaerythritol, and 2.5 g of melamine, stir at a speed of 300 r / min for 3 h, and then stir at a speed of 60 r / min for 2 h to obtain a uniformly mixed base material;

[0028] S2: Preparation of CN@GO hybrid material: disperse 0.08 g of graphite phase cyanamide into 100 mL of graphene oxide solution (0.5 mg·mL -1 ), then ultrasonically treat for 30 min, and stir with a magnetic stirrer for 12 h, then filter and wash the product, and dry at 60°C for 12 h to obtain the CN@GO hybrid material;

[0029] S3: Preparation of CN@GO@LAA hybrid material: ultrasonically disperse 0.05 g of CN@GO in deionized water, then add 0.04 g of L-ascorbic acid, and stir with a magnetic stirrer for 1 h, then centrifuge and wash the product to obtain the CN@GO@LAA hybrid material;

[0030] S4: Preparation of CN@GO@LAA@Cu hybrid material: ultrasonically disperse 0.05 g of CN@GO@LAA in 100 mL of water, then add 2 g of copper acetate, and stir with a magnetic stirrer for 2 h, then centrifuge and wash the product to obtain the CN@GO@LAA@Cu hybrid material;

[0031] S5: Preparation of environmentally friendly CN@GO@LAA@Cu intumescent fire retardant coating: Mix 98g of base material and 2g of CN@GO@LAA@Cu hybrid material, and stir mechanically for 5 hours to form a uniformly dispersed system. Then, apply the uniformly dispersed system to the surface of a steel sheet. After the coating is completed, cure at room temperature for 7 days to obtain the environmentally friendly CN@GO@LAA@Cu intumescent fire retardant coating.

[0032] This embodiment demonstrates the experimental analysis results related to the preparation method of the environmentally friendly CN@GO@LAA@Cu intumescent fire-retardant coating proposed in this paper.

[0033] Water-based intumescent fire retardant coatings CN / EP, CN@GO / EP, CN@GO@LAA, and CN@GO@LAA@Cu and 98g of base material were prepared respectively. Pure epoxy resin (EP) was used as a control. The fire retardant coatings were applied to sandblasted steel sheets and cured at room temperature for 7 days to obtain test samples.

[0034] (1) The morphology of CN, CN@GO, CN@GO@LAA and CN@GO@LAA@Cu nanohybrids was observed using a JEOL JEM-2100 high-resolution transmission electron microscope (HR-TEM). The results are shown in the appendix. Figure 1 .from Figure 1 As can be seen in A and E, CN exhibits a rough, sheet-like structure. After being combined with graphene oxide ( Figure 1 B and F)) can be observed to reveal rough carbon nitride sheets and graphene oxide sheets exhibiting a typical wrinkled structure. After modification with L-ascorbic acid and copper ions ( Figure 1 C and G) and ( Figure 1 D and H)) showed no significant changes on the material surface. To further investigate the copper ion loading, we performed elemental surface scans on the CN@GO@LAA@Cu hybrid material using a JSM-7500F scanning electron microscope, such as Figure 1 As shown in I, J, K, and L. The elemental scan results show that CN@GO@LAA@Cu is composed of C, N, O, and Cu elements, which are uniformly distributed on the surface of the hybrid material. The uniform distribution of Cu elements indicates uniform loading of copper ions, suggesting the successful synthesis of the CN@GO@LAA@Cu hybrid material.

[0035] (2) The cross-sectional morphology of each fire-retardant coating was observed using a JSM-7500F scanning electron microscope. The results are shown in the appendix. Figure 2 .like Figure 2 As shown in Figure A, the fracture surface of pure EP was observed to be relatively smooth. When 2.0 wt% graphitic carbon nitride was added ( Figure 2B) Agglomeration and pores were observed on the fracture surface, indicating that the original graphitic carbon nitride phase had poor dispersion and weak interaction with the epoxy resin. After modification with graphene oxide ( Figure 2 C) The dispersibility of CN@GO is significantly improved, with only small pores remaining on the fracture surface. L-ascorbic acid and Cu are introduced onto the surface. 2+ Subsequently, it was observed that CN@GO@LAA and CN@GO@LAA@Cu exhibited good dispersion in the matrix, and CN@GO@LAA / EP ( Figure 2 D) and CN@GO@LAA@Cu / EP( Figure 2 E) Both exhibit rough and uneven wrinkled surfaces, indicating a strong interfacial interaction between the two fillers and the polymer.

[0036] (3) The fire-retardant performance of the coating was tested by measuring the temperature on the back of the steel plate using the large plate method. The results are shown in the appendix. Figure 3 .from Figure 3 It can be seen that the water-based intumescent fire retardant coating containing CN@GO@LAA@Cu nano-hybrid materials has the lowest temperature on the back of the steel plate, which is 40.7% lower than that of pure EP. This indicates that CN@GO@LAA@Cu can effectively improve the strength and barrier function of the char layer, thereby effectively slowing down the temperature rise on the back of the steel plate and improving the fire resistance performance.

[0037] (4) The expansion behavior of the water-based intumescent fire retardant coating was studied through furnace testing. The results are shown in the appendix. Figure 4 .from Figure 4 As can be seen from A, pure EP expands unevenly with an extremely low expansion height. After adding flame-retardant filler, the expansion height increases somewhat. Figure 4 BE). It is worth noting that, compared to pure EP, CN@GO@LAA@Cu / EP ( Figure 4 E) The expansion height increased by 298.3%, and the coating expanded uniformly, with a dense and homogeneous carbon layer, which is beneficial for blocking heat and combustible gases.

[0038] (5) The structure of the carbon layer after the large-plate test was tested using a JSM-7500F scanning electron microscope. The results are shown in the appendix. Figure 5 For pure EP ( Figure 5 As can be observed in Figure A, numerous pores and cracks indicate that the carbon layer cannot provide effective protection for the polymer matrix. Significant changes were observed after the addition of filler. CN / EP( Figure 5 B) Reduced porosity and crack size in the carbon layer enhances its barrier properties. CN@GO / EP( Figure 5 C) The cracks in the carbon layer are further reduced, which is attributed to the excellent dispersion of graphitic carbon nitride by graphene oxide, further enhancing its barrier properties. CN@GO@LAA / EP(Figure 5 D) The carbon layer cracks disappear, and only a few small holes exist on the carbon layer surface, because LAA promotes the thermal reduction of GO network, and generates reduced graphene oxide with stronger thermal stability. For CN@GO@LAA@Cu / EP( Figure 5 E), no cracks and holes are found, and the carbon layer is complete and dense, because the generated CuO and Cu2O catalyze the formation of more coke, and the carbon layer strength increases. The dense and complete carbon layer can well resist heat mass transfer and play a barrier role, thereby improving the fireproof performance.

[0039] The preparation method of the environment-friendly CN@GO@LAA@Cu intumescent fireproof coating provided by the application solves the potential dangerous characteristics of low carbon layer strength, uneven expansion and poor fireproof performance of the current water-based fireproof coating, and the obtained water-based intumescent fireproof coating can form a uniform and dense expanded carbon layer at high temperature, block the heat transfer to the steel structure, and play a good protection role. The application is mainly used for steel structure fire protection, and prolongs the time for the steel structure to reach the failure temperature and collapse under fire, thereby gaining valuable rescue time for fire fighting. The water-based intumescent fireproof coating has the advantages of easy availability of raw materials, simple preparation, low cost, water-based environmental protection, and wide industrial application value.

[0040] The above description does not limit the application in any form, although the application has been disclosed by the above examples, however, is not intended to limit the application, any skilled person in the art, without departing from the technical solution of the application, can use the disclosed technical content to make some changes or modifications for equivalent examples of equivalent changes, but as long as it does not deviate from the content of the technical solution of the application, according to the technical essence of the application, any simple modification, equivalent change and modification of the above examples, still belongs to the range of the technical solution of the application.

Claims

1. A method for preparing an environmentally friendly CN@GO@LAA@Cu intumescent fire-retardant coating, characterized in that, Includes the following steps: S1: Preparation of base material: Weigh a certain amount of waterborne epoxy resin, curing agent, melamine polyphosphate, dipentaerythritol and melamine, stir at a rate of 300 r / min for 3 h, and then stir at a rate of 60 r / min for 2 h to obtain a uniformly mixed base material. S2: Preparation of CN@GO hybrid material: A certain amount of graphitic carbon nitride was dispersed in 100 mL of graphene oxide solution, wherein the concentration of graphene oxide solution was 0.5 mg·mL⁻¹. -1 Then, the mixture was sonicated for 30 minutes and stirred with a magnetic stirrer for 12 hours. The product was then filtered, washed, and dried at 60°C for 12 hours to obtain CN@GO hybrid material. S3: Preparation of CN@GO@LAA hybrid material: A certain amount of CN@GO hybrid material was ultrasonically dispersed in deionized water, then a certain amount of L-ascorbic acid was added, and the mixture was stirred with a magnetic stirrer for 1 hour. After centrifugation and washing, the CN@GO@LAA hybrid material was obtained. S4: Preparation of CN@GO@LAA@Cu hybrid material: A certain amount of CN@GO@LAA hybrid material was ultrasonically dispersed in 100mL of water, then a certain amount of copper acetate was added, and the mixture was stirred with a magnetic stirrer for 2h. After centrifugation and washing, the CN@GO@LAA@Cu hybrid material was obtained. S5: Preparation of environmentally friendly CN@GO@LAA@Cu intumescent fire retardant coating: A certain amount of base material and a certain amount of CN@GO@LAA@Cu hybrid material are mixed and mechanically stirred for 5 hours to form a uniformly dispersed system. The uniformly dispersed system is then brushed onto the surface of a steel sheet. After brushing, it is cured at room temperature for 7 days to obtain the environmentally friendly CN@GO@LAA@Cu intumescent fire retardant coating.

2. The preparation method of the environmentally friendly CN@GO@LAA@Cu intumescent fire-retardant coating as described in claim 1, characterized in that, In step S1, the mass ratio of melamine polyphosphate, dipentaerythritol, and melamine is 6:3:

1.

3. The preparation method of the environmentally friendly CN@GO@LAA@Cu intumescent fire-retardant coating as described in claim 1, characterized in that, In step S2, the mass ratio of graphitic carbon nitride to graphene oxide is 1-2:

1.

4. The preparation method of the environmentally friendly CN@GO@LAA@Cu intumescent fire-retardant coating as described in claim 1, characterized in that, In step S3, the mass ratio of CN@GO hybrid material to L-ascorbic acid is 1-1.5:

1.

5. The preparation method of the environmentally friendly CN@GO@LAA@Cu intumescent fire-retardant coating as described in claim 1, characterized in that, In step S4, the mass ratio of CN@GO@LAA hybrid material to copper acetate is 1:35-45.

6. The preparation method of the environmentally friendly CN@GO@LAA@Cu intumescent fire-retardant coating as described in claim 1, characterized in that, In step S5, the CN@GO@LAA@Cu hybrid material accounts for 2%-6% of the total weight of the uniformly dispersed system.

Images