Rapid detection method for intumescent steel structure fireproof coating core flame retardant based on rapid colorimetric technology and detection kit and application thereof

Abstract

The invention belongs to the field of rapid detection of flame retardants, and particularly relates to a rapid detection method for a core flame retardant of an intumescent steel structure fireproof coating based on a rapid colorimetric technology and a detection kit and application thereof. The xylenol orange-zirconium system is used for rapidly detecting the core flame retardant ammonium polyphosphate in the steel structure fireproof coating for the first time. According to the method provided by the invention, sampling, detection and interpretation can be completed on site within 30 minutes. A supervision node can be moved forward to key links such as paint entering and before construction, afterward responsibility investigation is changed into beforehand prevention, and supervision initiative and deterrent force are greatly improved. The method is low in cost and easy and convenient to operate, the supervision cost of wide screening can be greatly reduced, and the sampling coverage rate is increased. Market purification is facilitated, regular enterprises are protected, and healthy and ordered development of the steel structure fireproof industry is promoted.

Description

Technical Field

[0001] This invention belongs to the field of rapid detection of flame retardants, specifically relating to a rapid detection method for the core flame retardant of intumescent steel structure fireproof coatings based on rapid colorimetric technology, as well as its detection kit and applications. Background Technology

[0002] Intumescent fire-retardant coatings for steel structures are an effective passive fire protection measure. Under high temperatures or flames, the coating foams and carbonizes, forming a dense, expanded char layer dozens of times thicker than the original coating. This effectively delays the temperature rise of steel components, providing a crucial time window for ensuring the structural integrity of the building and for the safe evacuation and rescue of personnel. The protective efficacy of intumescent fire-retardant coatings for steel structures depends on the expansion system composed of a foaming agent, a charring agent, and a dehydration catalyst. This system directly determines the expansion ratio, thermal stability, and insulation performance of the char layer, and is a key quality factor affecting the final performance of the coating.

[0003] Currently, the testing and evaluation of intumescent fire-retardant coatings for steel structures mainly relies on the testing items specified in standards such as GB 14907-2018 "Fire-retardant Coatings for Steel Structures," specifically including: 1) fire resistance performance testing; 2) physical performance testing, such as dry density, bond strength, and compressive strength; and 3) chemical performance testing, such as pH value, water resistance, and acid resistance. Among these, fire resistance performance is a mandatory key indicator. This method suffers from long cycles, high costs, and inability to meet the practical needs of large-scale rapid sampling inspections. Ammonium polyphosphate is the most critical component determining fire resistance performance. As a dehydration catalyst, it catalyzes carbonization at high temperatures, directly determining whether the coating can effectively expand and foam, forming a heat-insulating protective layer. Therefore, developing efficient and rapid testing technologies for the core flame retardants of the intumescent system, enabling on-site screening and preliminary quality assessment of key functional components in coatings, will provide a powerful technical tool for improving the efficiency and coverage of fire protection product quality supervision, combating counterfeit and substandard products, and ensuring public fire safety. Summary of the Invention

[0004] To address the problems of long testing cycles, high costs, and inability to meet the needs of large-scale rapid sampling in existing technologies, this invention provides a rapid testing method for the core flame retardant (APP) in intumescent fire-retardant coatings for steel structures based on rapid colorimetric technology. This method involves adding the sample to a test reagent and quickly determining the presence of APP in the coating by observing the color change of the liquid. It offers advantages such as low cost, ease of operation, and significant reduction in the regulatory costs of extensive screening. This method is applicable to both uncoated coatings and dried coatings applied to steel structure surfaces, making it widely applicable.

[0005] Another object of the present invention is to provide a detection kit prepared based on the above-described rapid detection method.

[0006] The present invention further provides the application of the above-mentioned test kit in the rapid detection of core flame retardants in intumescent fireproof coatings for steel structures.

[0007] The technical solution adopted by the present invention to achieve the above objectives is as follows: This invention provides an application of the xylenol orange-zirconium system in the rapid detection of ammonium polyphosphate (APP) in fire-retardant coatings for steel structures.

[0008] Another objective of this invention is to provide a rapid detection method for the core flame retardant of intumescent fire-retardant coatings for steel structures based on rapid colorimetric technology, comprising the following steps: When the sample to be tested is an uncoated paint: (1) Take the sample to be tested, add solvent to dilute it, and stir until it becomes an emulsion or suspension to obtain the sample dilution solution; (2) Add the well-mixed sample diluent to the test solution, shake well, let stand, and compare the experimental results with the control group and the blank group to determine whether the sample contains APP; When the sample to be tested is a dried coating applied to the surface of a steel structure, and step (1) can form an emulsion or suspension, then step (2) is as follows: (2) Add the test solution to the scratch with powder, let it stand, and compare the experimental results with the control group and the blank group to determine whether the sample contains APP.

[0009] Preferably, in step (1), the mass percentage of the sample to be tested to the solvent is less than or equal to 30%; the solvent is deionized water or N,N-dimethylformamide.

[0010] Preferably, in step (2), the detection solution is a mixture of xylenol orange aqueous solution and zirconium oxychloride octahydrate aqueous solution, with a concentration ratio and volume ratio of 1:1; the concentration of the xylenol orange aqueous solution is 0.005-0.01 mol / L; and the concentration of the zirconium oxychloride octahydrate aqueous solution is 0.005-0.01 mol / L.

[0011] Preferably, in step (2), when the sample to be tested is an uncoated paint, the volume ratio of the test solution to the sample diluent is 1.5 mL: 0.25-0.5 mL; when the sample to be tested is a dried coating applied to the surface of a steel structure, 0.15-0.25 mL of test solution is added at a depth of 2-3 mm on the surface of the steel structure where the coating scratch is located.

[0012] Preferably, the settling time is 10-15 minutes.

[0013] Preferably, in step (2), when the sample to be tested is an uncoated paint, the control group uses a test solution with the same volume of a reference standard containing 1 wt% APP as the sample diluent; the blank group uses a test solution with the same volume of deionized water as the sample diluent; when the sample to be tested is a dried coating applied to the surface of a steel structure, the control group uses a test solution with a reference standard containing 1 wt% APP, and the blank group uses the original test solution.

[0014] The present invention also provides a detection kit prepared based on the above-described rapid detection method.

[0015] This invention further provides the application of the above-mentioned test kit in the rapid detection of core flame retardants in intumescent fire-retardant coatings for steel structures.

[0016] Preferably, when using the test kit, if the sample cannot be dissolved completely after adding solvent to dilute it, the sample is determined to be unsuitable for colorimetric detection, and the test is terminated. The beneficial effects of this invention are as follows: (1) The method provided by this invention can complete sampling, testing and interpretation on-site within 30 minutes. It can move the supervision node forward to key links such as paint entry and construction, change post-event accountability to pre-event prevention, and greatly improve the initiative and deterrent effect of supervision.

[0017] (2) This method is low-cost and easy to operate, which can significantly reduce the regulatory costs of extensive screening and increase the coverage of random inspections. It is conducive to purifying the market, protecting legitimate enterprises, and promoting the healthy and orderly development of the steel structure fireproofing industry. Attached Figure Description

[0018] Figure 1 The image shows the results of testing uncoated areas using the detection method of Example 1. Figure 2 The image shows the results of testing uncoated areas using the detection method of Example 2. Figure 3 The image shows the results of testing uncoated areas using the detection method of Example 3. Figure 4 The image shows the results of testing uncoated areas using the detection method of Example 4. Figure 5 The image shows the results of testing uncoated areas using the detection method of Example 5. Figure 6 The image shows the results of testing uncoated areas using the detection method of Example 6. Figure 7 The image shows the results of the coating after application, obtained using the detection method of Example 7. Figure 8 To detect the color change of APP with different degrees of polymerization added dropwise to the solution; Figure 9 This is a schematic diagram illustrating the mechanism of the rapid detection method provided by the present invention; Figure 10 A comparison chart showing the dissolution of solvent-based coatings with different solvents. Detailed Implementation

[0019] The present invention will now be described in detail with reference to specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.

[0020] The rapid detection method provided by this invention has the following schematic diagram of its detection mechanism: Figure 9 As shown: For uncoated paint: (1) Use a disposable syringe to draw 1 mL of paint sample, add 9 mL of solvent to dilute it, and observe the sample solubility. If the sample still cannot be dissolved completely after changing the solvent, it is determined that the sample is not suitable for colorimetric detection and the test is ended; if it can be partially dissolved and forms an emulsion or suspension, it is ready for use and the test is continued. (2) Take the test solution into the sample tube, add the well-mixed sample diluent, shake well, let stand for 10 min, and compare the experimental results with the control group and the blank group. The blank group solution is a purple-red liquid, and the control group solution is an orange liquid. Compared with the blank group, if the solution does not change color, it is determined that no APP has been added to the sample coating, APP has failed, or the degree of APP polymerization is insufficient. Compared with the control group, if the solution shows an orange phase, it is determined that a certain amount of APP has been added to the sample coating.

[0021] When testing water-soluble coatings, water is used as the solvent; when testing solvent-based coatings, N,N-dimethylformamide is used.

[0022] For coatings that have been applied to the surface of steel structures and have already dried: (1) Use a knife to scrape off some powder from the dried coating on the steel structure surface, add solvent to dilute it, and observe the sample solubility. If the sample cannot be dissolved at all, it is determined that the sample is not suitable for colorimetric detection and the test ends; if it can be partially dissolved and forms an emulsion or suspension, it is ready for use and the test continues. (2) Add 3-5 drops of the test solution to the scratch with powder, let stand for 10 min, and compare the experimental results with the control group and the blank group. The solution in the blank group is a purple-red liquid, and the solution in the control group is an orange liquid. Compared with the blank group, if the test solution added to the coating does not change color, it is determined that no APP has been added to the sample coating, APP has failed, or the degree of polymerization of APP is insufficient. Compared with the control group, if the test solution added to the coating shows an orange phase, it is determined that a certain amount of APP has been added to the sample coating.

[0023] Example 1 (1) Use a disposable syringe to draw 1 mL of the paint sample of brand 1, add 9 mL of deionized water for dilution, observe the sample solubility, and find that the sample system can be partially dissolved and the granular powder can be evenly dispersed. Therefore, it is determined that the paint sample of this embodiment can be used for this detection method and is ready for use. (2) The control group used a test solution with the same volume of 1 wt% APP content as the sample diluent; the blank group used a test solution with the same volume of deionized water as the sample diluent. (3) Take 1.5 mL of the test solution (composed of 0.01 mol / L xylenol orange aqueous solution and 0.01 mol / L zirconium oxychloride octahydrate aqueous solution in a volume ratio of 1:1) into a sample tube, add 6 drops (about 0.3 mL) of well-mixed sample diluent, shake well, let stand for 10 min, and compare with the control group and blank group. It was found that the liquid turned orange. Figure 1 As shown, it can be determined that a certain amount of APP has been added to the sample coating.

[0024] Example 2 (1) Use a disposable syringe to draw 1 mL of brand 2 paint sample, add 9 mL of deionized water for dilution, observe the sample solubility, and find that the sample system can be partially dissolved and the granular powder can be evenly dispersed. Therefore, it is determined that the paint sample in this embodiment can be used for this detection method and is ready for use. (2) Take 1.5 mL of the test solution (same as in Example 1) into a sample tube, add 6 drops of the well-mixed sample diluent, shake well, let stand for 10 min, and compare with the control group (same as in Example 1) and the blank group (same as in Example 1). It was found that the liquid turned orange. Figure 2 If so, it is determined that a certain amount of APP has been added to the sample coating.

[0025] Example 3 (1) Use a disposable syringe to draw 1 mL of brand 3 paint sample, add 9 mL of deionized water for dilution, observe the sample solubility, and find that the sample system can be partially dissolved and the granular powder can be evenly dispersed. Therefore, it is determined that the paint sample in this embodiment can be used for this detection method and is ready for use. (2) Take 1.5 mL of the test solution (same as in Example 1) into a sample tube, add 6 drops of the well-mixed sample diluent, shake well, let stand for 10 min, and compare with the control group (same as in Example 1) and the blank group (same as in Example 1). It was found that the color did not change. Figure 3 If the result is negative, it is determined that the sample coating did not contain APP, the APP was ineffective, or the degree of APP polymerization was insufficient.

[0026] Example 4 (1) Use a disposable syringe to draw 1 mL of brand 4 paint sample, add 9 mL of N,N-dimethylformamide for dilution, observe the sample solubility, and find that the sample system can be partially dissolved and the granular powder can be evenly dispersed. Therefore, it is determined that the paint sample in this embodiment can be used for this detection method and is ready for use. (2) Take 1.5 mL of the test solution (same as in Example 1) into a sample tube, add 6 drops of the well-mixed sample diluent, shake well, let stand for 10 min, and compare with the control group (same as in Example 1) and the blank group (same as in Example 1). It was found that the liquid turned orange. Figure 4 If so, it is determined that a certain amount of APP has been added to the sample coating.

[0027] Example 5 (1) Use a disposable syringe to draw 1 mL of brand 5 paint sample, add 9 mL of N,N-dimethylformamide for dilution, observe the sample solubility, and find that the sample system can be partially dissolved and the granular powder can be evenly dispersed. Therefore, it is determined that the paint sample in this embodiment can be used for this detection method and is ready for use. (2) Take 1.5 mL of the test solution (same as in Example 1) into a sample tube, add 6 drops of the well-mixed sample diluent, shake well, let stand for 10 min, and compare with the control group (same as in Example 1) and the blank group (same as in Example 1). It was found that the liquid turned orange. Figure 5 If so, it is determined that a certain amount of APP has been added to the sample coating.

[0028] Example 6 (1) Use a disposable syringe to draw 1 mL of brand 6 paint sample, add 9 mL of N,N-dimethylformamide for dilution, observe the sample solubility, and find that the sample system can be partially dissolved and the granular powder can be evenly dispersed. Therefore, it is determined that the paint sample in this embodiment can be used for this detection method and is ready for use. (2) Take 1.5 mL of the test solution (same as in Example 1) into a sample tube, add 6 drops of the well-mixed sample diluent, shake well, let stand for 10 min, and compare with the control group (same as in Example 1) and the blank group (same as in Example 1). It was found that the color did not change. Figure 6 If the result is negative, it is determined that the sample coating did not contain APP, the APP was ineffective, or the degree of APP polymerization was insufficient.

[0029] Example 7 (1) Prepare a small plate of coating of brand 7 coated on the surface of steel structure and dried. Use a knife to scrape some powder off the coating surface, add solvent to dilute it, and observe the solubility of the sample. It is found that the sample system can be partially dissolved and the powder particles can be evenly dispersed. Therefore, it is determined that the coating sample of this embodiment can be used for this test method and is ready for use. (2) Add 5 drops of the test solution (same as in Example 1) to the scratch with powder, let stand for 10 min, and compare the experimental results with the control group (test solution with 1 wt% APP content) and the blank group (original test solution). It was found that the test solution added to the coating turned orange, such as Figure 7 If so, it is determined that a certain amount of APP has been added to the sample coating.

[0030] Example 8 (1) Take 1.5 mL of the test solution into a sample tube, and add 200 μL of 10 wt% high (degree of polymerization ≥ 1000), medium (degree of polymerization 30-50), and low (degree of polymerization ≤ 20) APP solutions respectively. Shake well and let stand for 10 min. The results show that the test solutions with high and medium degree of polymerization APP solutions turned orange, while the test solutions with low degree of polymerization APP solutions did not change color. Figure 8 .

[0031] Intumescent fireproof coatings for steel structures, APP coatings with low polymerization degree have poor performance. From the perspective of coating testing, APP coatings with low polymerization degree are inherently unqualified products.

[0032] Comparative Example 1 Using a disposable syringe, 1 mL of Brand 1 paint sample was drawn and diluted with 9 mL of dichloromethane (MC) or dimethyl sulfoxide (DMSO). When testing solvent-based paints, they are soluble in dichloromethane, but dichloromethane is insoluble in water, and the test reagent is an aqueous solution, therefore detection is impossible. DMSO is soluble in water, but solvent-based paints are insoluble in DMSO, making normal testing impossible. Specific comparison results are as follows... Figure 10 As shown.

Claims

1. Application of a xylenol orange-zirconium system in the rapid detection of ammonium polyphosphate (APP) in intumescent fire-retardant coatings for steel structures.

2. A rapid detection method for the core flame retardant of intumescent fire-retardant coatings for steel structures based on rapid colorimetric technology, characterized in that, Includes the following steps: When the sample to be tested is an uncoated paint: (1) Take the sample to be tested, add solvent to dilute it, and stir until it becomes an emulsion or suspension to obtain the sample dilution solution; (2) Add the well-mixed sample diluent to the test solution, shake well, let stand, and compare the experimental results with the control group and the blank group to determine whether the sample contains APP; When the sample to be tested is a dried coating applied to the surface of a steel structure, and step (1) can form an emulsion or suspension, then step (2) is as follows: (2) Add the test solution to the scratch with powder, let it stand, and compare the experimental results with the control group and the blank group to determine whether the sample contains APP.

3. The rapid detection method according to claim 2, characterized in that, In step (1), the mass percentage of the sample to be tested to the solvent is less than or equal to 30%; the solvent is deionized water or N,N-dimethylformamide.

4. The rapid detection method according to claim 2, characterized in that, In step (2), the detection solution is a mixture of xylenol orange aqueous solution and zirconium oxychloride octahydrate aqueous solution, with a concentration ratio and volume ratio of 1:1; the concentration of xylenol orange aqueous solution is 0.005-0.01 mol / L; the concentration of zirconium oxychloride octahydrate aqueous solution is 0.005-0.01 mol / L.

5. The rapid detection method according to claim 2 or 4, characterized in that, In step (2), when the sample to be tested is an uncoated paint, the volume ratio of the test solution to the sample diluent is 1.5 mL: 0.25-0.5 mL; when the sample to be tested is a dried coating on the surface of a steel structure, 0.15-0.25 mL of test solution is added at a depth of 2-3 mm on the surface of the steel structure where the coating scratch is located.

6. The rapid detection method according to claim 2, 4 or 5, characterized in that, The settling time is 10-15 minutes.

7. The rapid detection method according to any one of claims 2-6, characterized in that, In step (2), when the sample to be tested is an uncoated paint, the control group uses a test solution with the same volume of a reference standard containing 1 wt% APP as the sample diluent; the blank group uses a test solution with the same volume of deionized water as the sample diluent; when the sample to be tested is a dried coating on the surface of a steel structure, the control group uses a test solution with a reference standard containing 1 wt% APP, and the blank group uses the original test solution.

8. A test kit prepared based on the rapid detection method according to any one of claims 2-7.

9. The application of the test kit as described in claim 8 in the rapid detection of the core flame retardant in intumescent fireproof coatings for steel structures.

10. The application according to claim 9, characterized in that, When using the aforementioned test kit, if the sample cannot be dissolved completely after adding solvent to dilute it, the sample is determined to be unsuitable for colorimetric detection, and the test is terminated.

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