Method for evaluating storage stability of polyurethane cold patch material based on NCO change and strength association

Abstract

The invention discloses a polyurethane cold patch material storage stability evaluation method based on NCO change and strength correlation, and relates to the technical field of road engineering materials.The method comprises the steps that sealed storage and pretreatment are conducted on a polyurethane cold patch material finished product for different times, and samples to be tested participating in different determination tests are prepared; measuring the NCO consumption rate before and after storage of the consumption sample to be measured by adopting a chemical titration method; measuring the NCO characteristic infrared peak area change rate before and after the storage of the characteristic peak sample to be measured by using an infrared spectroscopy method; the Marshall stability of the sample with the strength to be tested before and after storage is tested; establishing a relevance model of the NCO consumption rate, the NCO characteristic infrared peak area change rate and the Marshall stability; and formulating a storage stability division standard based on the Marshall stability after the polyurethane cold patch material is stored. According to the method, the attenuation degree of the chemical groups is predicted on the basis of the test result of the early strength of the cold patch material, and the storage stability is further scientifically evaluated.

Description

Technical Field

[0001] The present invention relates to the technical field of road engineering materials, and in particular to a method for evaluating the storage stability of a polyurethane cold patch material based on the correlation between NCO change and strength. Background Art

[0002] Polyurethane cold patch material is a new type of road repair material that has seen significant progress in research and application in recent years. Due to its excellent adhesion, elasticity, wear resistance, and outstanding weather resistance, this material is widely used in road pothole repair projects, particularly in high-standard repairs and harsh environments. A key advantage of this material is its effective application and rapid curing even in low-temperature environments. Compared to traditional asphalt cold patch material, polyurethane cold patch material not only maintains excellent workability in low-temperature conditions, but also has a shorter curing time and exceptionally long durability, leading to its increasing application in the road repair field.

[0003] Polyurethane cold patch material is primarily composed of a binder consisting of polyurethane (isocyanate and polyol), a diluent, a catalyst, a plasticizer, and appropriately graded aggregate and mineral powder. This material has excellent workability, early strength, and durability, making it widely used for rapid repairs of potholes in roads.

[0004] However, polyurethane cold patch material is extremely sensitive to moisture, which can react with the isocyanate (NCO) groups in polyurethane. During storage, if the ambient humidity is high, the NCO group will react with moisture, resulting in increased consumption of the NCO group, thereby affecting the construction performance of the polyurethane cold patch material. In addition, the performance of polyurethane cold patch material is significantly affected by multiple factors such as temperature, humidity, storage time and packaging conditions. At present, the specific influence of these factors on the performance of the material has not been fully clarified, and whether premature reaction, failure or performance degradation will occur during storage is still undetermined. Existing evaluation methods mostly rely on the observation of the degree of agglomeration after long-term field storage, or the evaluation of the effect after field pothole repair, which takes a long time (usually not less than 3 months), and the results are greatly affected by subjective factors.

[0005] Therefore, there is an urgent need to construct a rapid evaluation system that can quantitatively characterize the correlation between chemical group changes during storage and key properties (such as early strength). Summary of the Invention

[0006] Based on this, it is necessary to provide a storage stability evaluation method for polyurethane cold patch material based on the correlation between NCO change and strength to address the above technical problems.

[0007] The present invention provides a method for evaluating the storage stability of a polyurethane cold patch material based on the correlation between NCO change and strength, comprising:

[0008] S1. The finished polyurethane cold patch material is sealed and stored and pretreated for different periods of time to prepare test samples for different measurement tests;

[0009] S2. Determine the NCO consumption rate of the sample before and after storage by chemical titration;

[0010] S3, using infrared spectroscopy to measure the NCO characteristic infrared peak area change rate of the characteristic peak test sample before and after storage;

[0011] S4. Test the Marshall stability of the strength test sample before and after storage;

[0012] S5. Based on the test results of each experiment, a correlation model between NCO consumption rate, NCO characteristic infrared peak area change rate and Marshall stability was established;

[0013] S6. Based on the Marshall stability of polyurethane cold patch materials after storage, a storage stability classification standard is established.

[0014] Furthermore, the polyurethane cold patch material finished product is sealed and stored and pretreated for different periods of time to prepare test samples for different determination tests, including:

[0015] S11. Seal and store the finished polyurethane cold patch material in an accelerated aging environment;

[0016] S12, setting the storage time for sealed storage of different batches of cold patch material products, and collecting cold patch material samples before and after sealed storage in batches;

[0017] S13. Use tweezers to scrape three portions of cement powder of a preset mass from the surface of the cold patch material sample before and after storage, as the consumption test samples;

[0018] S14. Using tweezers, scrape three portions of cement powder of a preset mass from the surface of the cold patch material sample before and after storage, and use them as samples to be tested for characteristic peaks;

[0019] S15. Take out three portions of cold patch material of preset mass from the cold patch material samples before and after storage, as samples to be tested for strength.

[0020] Furthermore, the accelerated aging environment is a sealed environment, and the ambient temperature is 40±2° C. and the relative humidity is greater than or equal to 80%.

[0021] Furthermore, the NCO consumption rate of the sample to be tested before and after storage is determined by chemical titration.

[0022] S21. Place the stored consumption sample into a mixed solution of anhydrous toluene and di-n-butylamine-toluene, and shake thoroughly until uniformly mixed to obtain a mixed solution;

[0023] S22, leaving the mixed solution at room temperature until the consumed sample is completely dissolved;

[0024] S23, adding isopropyl alcohol to the mixed solution, and adding bromocresol green indicator dropwise until the mixed solution turns blue, stopping the addition to obtain a blue solution;

[0025] S24. Perform a titration test using a hydrochloric acid standard solution. When the color of the blue solution changes from blue to yellow, stop the titration and record the volume of the hydrochloric acid standard solution consumed.

[0026] S25. Perform S21-S24 using the sample to be tested with the consumption before storage to conduct a blank test;

[0027] S26. Based on the volume of the consumed hydrochloric acid standard solution, calculate the NCO consumption of the sample to be tested before and after storage using the NCO content formula of the cold patch material;

[0028] S27. Calculate the NCO consumption rate of the cold patch material after storage based on the NCO consumption of the sample to be tested before and after storage.

[0029] Furthermore, the NCO content formula of the cold patch material is:

[0030]

[0031] Where W is the content of NCO; V0 is the volume of the standard hydrochloric acid solution consumed in the blank test; V s is the volume of hydrochloric acid standard titration solution consumed during the sample test; C is the concentration of hydrochloric acid standard titration solution; m is the mass of the sample to be tested;

[0032] The calculation formula for NCO consumption rate is:

[0033]

[0034] Where, Δ NCO％ is the NCO consumption rate; W 存储前 is the NCO content in the sample to be tested before consumption; W 存储后 is the NCO content in the sample to be tested after consumption after storage under different conditions.

[0035] Furthermore, the NCO characteristic infrared peak area change rate of the characteristic peak to be tested before and after storage of the sample is determined by infrared spectroscopy, including:

[0036] S31, placing the characteristic peak test samples on the Fourier transform infrared spectrometer for online detection, setting the instrument parameters, including spectral resolution, number of scans and scanning range;

[0037] S32, collect the infrared spectrum after online detection by monitoring 2252cm -1 The isocyanate group at 2970 cm -1 Quantitative analysis is performed by tracking the change in the NCO characteristic infrared peak area of ​​the sample to be tested during storage.

[0038] Furthermore, the calculation formula for the change rate of the NCO characteristic infrared peak area is:

[0039]

[0040] Where I1 is 2252cm -1 The characteristic peak of -NCO group is from 2100-2400cm -1 The peak area calculated at the end of storage is the base; 10 2252cm -1 The characteristic peak of -NCO group is from 2100-2400cm -1 The peak area calculated at the start of storage is the base; I2 is 2970cm -1 The characteristic peak of -CH2 group is from 2900-3000cm -1 The peak area calculated at the end of storage is the base; 20 2970cm -1 The characteristic peak of -CH2 group is from 2900-3000cm -1 The peak area calculated at the start of storage is used as the base.

[0041] Furthermore, the Marshall stability of the strength test sample before and after storage is tested, including:

[0042] S41, weighing a preset mass of the strength test sample and placing it in a container, and evenly spraying a preset mass of water to fully mix the strength test sample and the water to obtain a mixture;

[0043] S42, transferring the mixture to a Marshall test mold, and using a ramming knife to tamp the mold along the periphery and the middle part. After the tamping is completed, the surface of the strength test sample is smoothed;

[0044] S43, compacting the leveled strength sample using a Marshall electric compactor, and curing the compacted strength sample under a preset temperature condition;

[0045] S44. Use a Marshall stability tester to measure the Marshall stability of the test sample after curing.

[0046] Furthermore, based on the test results of each experiment, a correlation model was established among the NCO consumption rate, the NCO characteristic infrared peak area change rate and the Marshall stability, including:

[0047] S51. Draw a curve showing the relationship between NCO consumption rate and Marshall stability.

[0048] S52. Draw a curve of the relationship between the rate of change of the NCO characteristic infrared peak area and the Marshall stability;

[0049] S53. Based on the two relationship curves drawn, a correlation model among the NCO consumption rate, the NCO characteristic infrared peak area change rate and the Marshall stability is established.

[0050] Furthermore, based on the Marshall stability of the polyurethane cold patch material after storage, the storage stability classification standards are formulated, including:

[0051] S61. Test the Marshall stability of the cold patch material sample and classify the storage stability grade according to the strength test value of the Marshall stability;

[0052] S62. Use the Marshall stability of the cold patch material after storage as an evaluation index to evaluate the storage stability of the polyurethane cold patch material.

[0053] The beneficial effects of the present invention are as follows: by constructing the NCO consumption rate before and after storage (Δ NCO％ ) and the NCO characteristic infrared peak area change rate (Δ A％ ) Same as Marshall stability after 1 hour storage (M 1h ) to predict the degree of chemical group attenuation based on the early strength test results of cold patch materials, and further scientifically evaluate their storage stability; it has the following significant advantages: 1. High efficiency: the evaluation cycle is greatly shortened from 3 to 6 months to 1 hour; 2. Quantification: with the help of Δ NCO％ , Δ A％ and M 1h 1. The three key indicators are linked to achieve accurate quantification of the material stability level; 2. Predictability: through the strength data 1 hour after storage, the risk of early strength loss after construction can be effectively predicted; 3. Universality: Applicable to MDI / TDI-based and other types of polyurethane cold patch material systems; This invention not only provides a reliable quantitative basis for the systematic analysis of the impact of different factors on the storage performance of materials, but also provides scientific support for optimizing the formula design and storage management strategy of polyurethane cold patch materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0055] Figure 1 This is a flow chart of a method for evaluating storage stability of a polyurethane cold patch material based on correlation between NCO change and strength according to an embodiment of the present invention;

[0056] Figure 2 2 is a schematic diagram of the change in the infrared characteristic peak area of ​​NCO according to an embodiment of the present invention;

[0057] Figure 3 is the Δ according to the embodiment of the present invention NCO％ , Δ A％ With M 1h The correlation model. DETAILED DESCRIPTION

[0058] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0059] See also Figure 1 , provides a storage stability evaluation method for polyurethane cold patch materials based on the correlation between NCO change and strength, including:

[0060] S1. The finished polyurethane cold patch material is sealed and stored and pretreated for different periods of time to prepare test samples for different measurement tests.

[0061] In the description of the present invention, the finished polyurethane cold patch material is sealed and stored and pretreated for different periods of time to prepare the test samples for participating in different measurement tests, including:

[0062] S11. Seal and store the finished polyurethane cold patch material in an accelerated aging environment.

[0063] The accelerated aging environment is a sealed environment with an ambient temperature of 40±2° C. and a relative humidity greater than or equal to 80%.

[0064] S12. Set the storage time for sealed storage of different batches of cold patch material products, and collect cold patch material samples before sealed storage and after sealed storage in batches.

[0065] Specifically, it is necessary to collect cold patch material samples before storage and cold patch material samples after storage for a period of time (test the cold patch material samples after storage for 1d, 3d, 7d, 30d, 60d, 90d, 180d, and 360d).

[0066] S13. Use tweezers to scrape three portions of preset mass (about 3 to 5 g each) of cement powder from the surface of the cold patch material sample before and after storage as the consumption samples to be tested.

[0067] S14. Use tweezers to scrape three portions of preset mass (about 5 to 20 mg each) of cement powder from the surface of the cold patch material sample before and after storage as samples for characteristic peak testing.

[0068] S15. Take out three portions of cold patch material with a preset mass (1220 g each) from the cold patch material samples before and after storage as samples to be tested for strength.

[0069] S2. Determine the NCO consumption rate of the sample before and after storage using a chemical titration method.

[0070] In the description of the present invention, the NCO consumption rate of the sample to be tested before and after storage is determined by chemical titration, including:

[0071] S21. Place the consumed sample to be tested (3-5 g) after storage in a mixed solution of 20 ml of anhydrous toluene and 10 ml of di-n-butylamine-toluene, and shake thoroughly until uniformly mixed to obtain a mixed solution.

[0072] S22. Let the mixed solution stand at room temperature for 30 to 60 minutes until the sample to be tested is completely dissolved.

[0073] S23. Add 50 ml of isopropanol to the mixed solution, and add bromocresol green indicator (5-10 drops) dropwise until the mixed solution turns blue. Stop adding dropwise to obtain a blue solution.

[0074] S24. Use 0.5 mol / L hydrochloric acid standard solution to perform a titration test. When the color of the blue solution changes from blue to yellow, stop the titration and record the volume of the hydrochloric acid standard solution consumed.

[0075] S25. Perform S21-S24 using the sample to be tested with the amount consumed before storage to conduct a blank test.

[0076] S26. Based on the volume of the consumed hydrochloric acid standard solution, calculate the NCO consumption of the sample to be tested before and after storage using the NCO content formula of the cold patch material.

[0077] In the description of the present invention, the NCO content formula of the cold patch material is:

[0078]

[0079] Where, W is the content of NCO, in %; V0 is the volume of hydrochloric acid standard titration solution consumed in the blank test, in ml; V s is the volume of hydrochloric acid standard titration solution consumed during the sample test, in ml; C is the concentration of hydrochloric acid standard titration solution, in mol / L; m is the mass of the sample to be tested, in g.

[0080] S27. Calculate the NCO consumption rate of the cold patch material after storage based on the NCO consumption of the sample to be tested before and after storage.

[0081] The calculation formula for NCO consumption rate is:

[0082]

[0083] Where, Δ NCO％ is the NCO consumption rate; W 存储前 is the NCO content in the sample to be tested before storage, in %; W 存储后 It is the NCO content in the sample after consumption under different storage conditions, in %.

[0084] S3. Using infrared spectroscopy, determine the rate of change of the NCO characteristic infrared peak area of ​​the characteristic peak sample before and after storage.

[0085] In the description of the present invention, the NCO characteristic infrared peak area change rate of the characteristic peak to be tested sample before and after storage is determined by infrared spectroscopy, including:

[0086] S31, 5 to 20 mg of the characteristic peak sample to be tested is placed on the Fourier transform infrared spectrometer for online detection, and the instrument parameters are set. The instrument parameters include spectral resolution, number of scans and scanning range. For example, the spectral resolution is set to 4 cm -1 , scanning times 64 times, scanning range 4000cm -1 ~400cm -1 .

[0087] S32, collect the infrared spectrum after online detection by monitoring 2252cm -1 The isocyanate group (-NCO) at 2970 cm -1 The quantitative analysis is carried out by tracking the change of the NCO characteristic infrared peak area of ​​the sample to be tested during storage. The change of the NCO infrared characteristic peak area is as follows: Figure 2 shown.

[0088] In the description of the present invention, the calculation formula of the NCO characteristic infrared peak area change rate is:

[0089]

[0090] Where I1 is 2252cm -1 The characteristic peak of -NCO group is from 2100-2400cm -1 The peak area calculated at the end of storage is the base; 10 2252cm -1The characteristic peak of -NCO group is from 2100-2400cm -1 The peak area calculated at the start of storage is the base; I2 is 2970cm -1 The characteristic peak of -CH2 group is from 2900-3000cm -1 The peak area calculated at the end of storage is the base; 20 2970cm -1 The characteristic peak of -CH2 group is from 2900-3000cm -1 The peak area calculated at the start of storage is used as the base.

[0091] S4. Test the Marshall stability of the strength sample before and after storage.

[0092] In the description of the present invention, the Marshall stability of the strength of the sample to be tested before and after storage is tested includes:

[0093] S41. Weigh a preset mass of the strength test sample (1220 g) and place it in a container. Evenly spray a preset mass of water (25 g) to fully mix the strength test sample and the water to obtain a mixture.

[0094] S42. Transfer the mixture to a Marshall test mold and use a ramming knife to tamp along the periphery and middle of the test mold (for example, use a ramming knife to tamp along the periphery of the test mold 15 times and tamp along the middle of the test mold 10 times to enhance the density of the mixture). After the ramming is completed, smooth the surface of the sample to be tested for strength.

[0095] S43. Use a Marshall electric compactor to compact the strength samples after leveling, and cure the compacted strength samples under preset temperature conditions (for example, compact both sides of the prepared specimen 75 times, and cure the compacted cold patch material specimen at 25°C for 1 hour).

[0096] S44. Use a Marshall stability tester to measure the Marshall stability of the test sample after curing.

[0097] S5. Based on the measurement results of various tests, a correlation model between NCO consumption rate, NCO characteristic infrared peak area change rate and Marshall stability was established.

[0098] In the description of the present invention, based on the measurement results of various experiments, a correlation model is established among the NCO consumption rate, the NCO characteristic infrared peak area change rate and the Marshall stability, including:

[0099] S51. Draw a curve showing the relationship between NCO consumption rate and Marshall stability.

[0100] S52. Draw a curve showing the relationship between the rate of change of the NCO characteristic infrared peak area and the Marshall stability.

[0101] S53. Based on the two relationship curves drawn, a correlation model among the NCO consumption rate, the NCO characteristic infrared peak area change rate and the Marshall stability is established.

[0102] Among them, such as Figure 3 As shown, the mathematical expression of the correlation model is y = 28.62x 0.48 The model's goodness of fit was 90.37%. The correlation model did not consider the effects of factors such as storage time, formulation composition, and packaging method. It only established the relationship between NCO consumption and strength changes before and after storage, thus using 1-hour strength to predict storage effects.

[0103] S6. Based on the Marshall stability of polyurethane cold patch materials after storage, a storage stability classification standard is established.

[0104] In the description of the present invention, based on the Marshall stability of the polyurethane cold patch material after storage, the storage stability classification standards are formulated including:

[0105] S61. Test the Marshall stability of the cold patch material sample and classify the storage stability level according to the strength test value of the Marshall stability.

[0106] S62. Use the Marshall stability of the cold patch material after storage as an evaluation index to evaluate the storage stability of the polyurethane cold patch material.

[0107] Specifically, the storage stability of the cold patch material is determined by M 1h Different ranges of intensity values ​​are divided into the following four levels: 1h When ≥5kN, the cold patch material has basically no change and the storage stability is excellent; when 3kN<M 1h When ≤5kN, the cold patch material is slightly ineffective and the storage stability is good; when 0.6kN<M 1h When ≤3kN, the cold patch material is partially invalid (about 40%), and the storage stability is general; when M 1h When the force is ≤0.6kN, the cold patch material is basically ineffective and has poor storage stability.

[0108] The present invention is further described below with reference to specific embodiments.

[0109] Polyurethane cold patch materials are widely used in road pothole repair. However, the impact of factors such as temperature, humidity, and storage conditions on their storage stability remains unclear, and effective quantitative evaluation methods are lacking. This application proposes a storage stability assessment method for polyurethane cold patch materials based on the correlation between NCO changes and strength.

[0110] The specific implementation includes the following steps:

[0111] (1) Preparation process of finished polyurethane cold patch material: By precisely controlling the ratio of isocyanate (such as MDI, TDI) and polyol in the formula, a polyurethane prepolymer with an NCO content of 12.5% ​​is prepared. The polyurethane prepolymer, xylene solvent, quartz sand and silane coupling agent are fully stirred at room temperature in the required proportions to prepare a mother liquor. According to the AC-10C grading requirements, limestone with a particle size of 0-3mm and granite aggregates with particle sizes of 3-5mm and 5-10mm are prepared. At room temperature, 6% of the mother liquor is used to fully mix with the above aggregates to obtain the finished polyurethane cold patch material.

[0112] (2) Test steps for finished polyurethane cold patch material: Use tweezers to evenly scrape 3-5g of binder from the surface of the finished polyurethane cold patch material as a sample; and place the sample in a container containing 20ml of anhydrous toluene and 10ml of di-n-butylamine-toluene mixed solution, and shake it thoroughly to ensure uniform mixing. Then, let it stand at room temperature for 30-60min until the sample is completely dissolved. Add 50ml of isopropanol to the above solution and add 5-10 drops of bromocresol green indicator until the solution turns blue. Then, use 0.5mol / L hydrochloric acid standard solution for titration. When the color of the solution changes from blue to yellow, record the volume of hydrochloric acid standard solution consumed. At the same time, perform a blank test. According to the volume of hydrochloric acid standard titration solution consumed in the above test, determine the specific NCO content of the finished polyurethane cold patch material according to the NCO content calculation formula. At the same time, use Fourier transform infrared spectrometer to measure the infrared absorption peak of the sample.

[0113] After the finished polyurethane cold patch material is prepared, it is packaged in different ways and stored under different storage conditions. The specific packaging and storage methods are detailed in the Examples section.

[0114] Example 1

[0115] The finished polyurethane cold patch material was packaged in plastic bags and sealed only with hot rolled bags, and then stored at 25°C for 3 days. After taking out the cold patch material, the NCO content of the polyurethane cold patch material after storage was determined according to step (2) in the specific implementation method. Subsequently, the change in NCO consumption of the water-cured cold patch material before and after storage was calculated based on the NCO consumption rate formula. At the same time, infrared spectroscopy was performed on the stored samples, and the consumption of NCO groups was verified according to the formula. According to the storage stability grading standard of the finished polyurethane cold patch material, the storage stability of the material was quantitatively evaluated. The specific test results are shown in Table 1.

[0116] Example 2

[0117] The finished polyurethane cold patch material was packaged in plastic bags and sealed only with hot-rolled bags, and then stored at 60°C for 3 days. After taking out the cold patch material, the NCO content of the polyurethane cold patch material after storage was determined according to step (2) in the specific embodiment. Subsequently, the change in NCO consumption of the water-cured cold patch material before and after storage was calculated according to the NCO consumption rate formula. At the same time, infrared spectroscopy was performed on the stored samples, and the consumption of NCO groups was verified according to the formula. According to the storage stability grading standard of the finished polyurethane cold patch material, the storage stability of the material was quantitatively evaluated. The specific test results are shown in Table 1.

[0118] Example 3

[0119] The finished polyurethane cold patch material is packaged in plastic bags, sealed by hot rolling, and then placed in a sealed can. Subsequently, the sealed can is placed in a 25°C environment for 3 days. After taking out the cold patch material, the NCO content of the polyurethane cold patch material after storage is determined according to step (2) in the specific implementation method. Subsequently, the change in NCO consumption of the water-cured cold patch material before and after storage is calculated according to the NCO consumption rate formula. At the same time, the infrared spectroscopy test is performed on the stored sample, and the consumption of the NCO group is verified according to the formula. According to the storage stability grading standard of the finished polyurethane cold patch material, the storage stability of the material is quantitatively evaluated. The specific test results are shown in Table 1.

[0120] Example 4

[0121] The finished polyurethane cold patch material is packaged in plastic bags, sealed by hot rolling, and then placed in a sealed can. Subsequently, the sealed can is placed in a 60°C environment for 3 days. After taking out the cold patch material, the NCO content of the polyurethane cold patch material after storage is determined according to step (2) in the specific implementation method. Subsequently, the change in NCO consumption of the water-cured cold patch material before and after storage is calculated according to the NCO consumption rate formula. At the same time, the infrared spectroscopy test is performed on the stored sample, and the consumption of the NCO group is verified according to the formula. According to the storage stability grading standard of the finished polyurethane cold patch material, the storage stability of the material is quantitatively evaluated. The specific test results are shown in Table 1.

[0122] Example 5

[0123] The finished polyurethane cold patch material was packaged in an aluminum foil bag and sealed by hot melt sealing technology, and then stored at 25°C for 3 days. After taking out the cold patch material, the NCO content of the polyurethane cold patch material after storage was determined according to step (2) in the specific implementation method. Subsequently, the change in NCO consumption of the water-cured cold patch material before and after storage was calculated according to the NCO consumption rate formula. At the same time, an infrared spectroscopy test was performed on the stored sample, and the consumption of the NCO group was verified according to the formula. According to the storage stability grading standard of the finished polyurethane cold patch material, the storage stability of the material was quantitatively evaluated. The specific test results are shown in Table 1.

[0124] Example 6

[0125] The finished polyurethane cold patch material was packaged in an aluminum foil bag and sealed by hot melt sealing technology, and then stored at 60°C for 3 days. After taking out the cold patch material, the NCO content of the polyurethane cold patch material after storage was determined according to step (2) in the specific implementation method. Subsequently, the change in NCO consumption of the water-cured cold patch material before and after storage was calculated according to the NCO consumption rate formula. At the same time, an infrared spectroscopy test was performed on the stored sample, and the consumption of the NCO group was verified according to the formula. According to the storage stability grading standard of the finished polyurethane cold patch material, the storage stability of the material was quantitatively evaluated. The specific test results are shown in Table 1.

[0126] Example 7

[0127] The finished polyurethane cold patch material was packaged in aluminum foil bags and sealed by hot melt sealing technology, and then stored at 60°C for 30 days. After taking out the cold patch material, the NCO content of the polyurethane cold patch material after storage was determined according to step (2) in the specific implementation method. Subsequently, the change in NCO consumption of the water-cured cold patch material before and after storage was calculated according to the NCO consumption rate formula. At the same time, infrared spectroscopy was performed on the stored samples, and the consumption of NCO groups was verified according to the formula. According to the storage stability grading standard of the finished polyurethane cold patch material, the storage stability of the material was quantitatively evaluated. The specific test results are shown in Table 1.

[0128] In the above embodiment, the storage test results of the water-cured cold patch material are shown in Table 1:

[0129] Table 1: Storage performance test results of finished polyurethane cold patch material

[0130] <![CDATA[△ NCO％ ]]> <![CDATA[△ A％ ]]> 1h Marshall stability Storage stability grade Example 1 29.81 30.14 0.73 generally Example 2 42.12 40.56 0.52 Poor Example 3 10.88 11.3 5.61 excellent Example 4 15.37 15.65 4.62 good Example 5 11.70 11.5 5.40 excellent Example 6 5.34 5.50 7.05 excellent Example 7 1.23 1.38 7.92 excellent

[0131] In summary, by means of the above technical solution of the present invention, by constructing the NCO consumption rate before and after storage (Δ NCO％ ) and the NCO characteristic infrared peak area change rate (Δ A％ ) Same as Marshall stability after 1 hour storage (M 1h) to predict the degree of chemical group attenuation based on the early strength test results of cold patch materials, and further scientifically evaluate their storage stability; it has the following significant advantages: 1. High efficiency: the evaluation cycle is greatly shortened from 3 to 6 months to 1 hour; 2. Quantification: with the help of Δ NCO％ , Δ A％ and M 1h 1. The three key indicators are linked to achieve accurate quantification of the material stability level; 2. Predictability: through the strength data 1 hour after storage, the risk of early strength loss after construction can be effectively predicted; 3. Universality: Applicable to MDI / TDI-based and other types of polyurethane cold patch material systems; This invention not only provides a reliable quantitative basis for the systematic analysis of the impact of different factors on the storage performance of materials, but also provides scientific support for optimizing the formula design and storage management strategy of polyurethane cold patch materials.

[0132] It should be understood that although the steps in the flowcharts of the accompanying drawings are shown in sequence as indicated by the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some of the steps in the flowcharts of the accompanying drawings may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and their execution order is not necessarily sequential, but can be executed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.

Claims

1. A method for evaluating the storage stability of polyurethane cold patch material based on the correlation between NCO change and strength, characterized in that: include: S1. The finished polyurethane cold patch material is sealed and stored and pretreated for different periods of time to prepare test samples for different measurement tests; S2. Determine the NCO consumption rate of the sample before and after storage by chemical titration; S3, using infrared spectroscopy to measure the NCO characteristic infrared peak area change rate of the characteristic peak test sample before and after storage; S4. Test the Marshall stability of the strength test sample before and after storage; S5. Based on the test results of each experiment, a correlation model between NCO consumption rate, NCO characteristic infrared peak area change rate and Marshall stability was established; S6. Based on the Marshall stability of polyurethane cold patch materials after storage, a storage stability classification standard is established.

2. The method for evaluating the storage stability of polyurethane cold patch material based on the correlation between NCO change and strength according to claim 1, characterized in that: The polyurethane cold patch material finished product is sealed and stored and pretreated for different periods of time to prepare test samples for participating in different measurement tests, including: S11. Seal and store the finished polyurethane cold patch material in an accelerated aging environment; S12, setting the storage time for sealed storage of different batches of cold patch material products, and collecting cold patch material samples before and after sealed storage in batches; S13. Use tweezers to scrape three portions of cement powder of a preset mass from the surface of the cold patch material sample before and after storage, as the consumption test samples; S14. Using tweezers, scrape three portions of cement powder of a preset mass from the surface of the cold patch material sample before and after storage, and use them as samples to be tested for characteristic peaks; S15. Take out three portions of cold patch material of preset mass from the cold patch material samples before and after storage, as samples to be tested for strength.

3. The method for evaluating the storage stability of polyurethane cold patch material based on the correlation between NCO change and strength according to claim 2, characterized in that: The accelerated aging environment is a sealed environment with an ambient temperature of 40±2° C. and a relative humidity greater than or equal to 80%.

4. The method for evaluating the storage stability of polyurethane cold patch material based on the correlation between NCO change and strength according to claim 2, characterized in that: The NCO consumption rate of the sample to be tested before and after storage using the chemical titration method for consumption determination includes: S21. Place the stored consumption sample into a mixed solution of anhydrous toluene and di-n-butylamine-toluene, and shake thoroughly until uniformly mixed to obtain a mixed solution; S22, leaving the mixed solution at room temperature until the consumed sample is completely dissolved; S23, adding isopropyl alcohol to the mixed solution, and adding bromocresol green indicator dropwise until the mixed solution turns blue, stopping the addition to obtain a blue solution; S24. Perform a titration test using a hydrochloric acid standard solution. When the color of the blue solution changes from blue to yellow, stop the titration and record the volume of the hydrochloric acid standard solution consumed. S25. Perform S21-S24 using the sample to be tested with the consumption before storage to conduct a blank test; S26. Based on the volume of the consumed hydrochloric acid standard solution, calculate the NCO consumption of the sample to be tested before and after storage using the NCO content formula of the cold patch material; S27. Calculate the NCO consumption rate of the cold patch material after storage based on the NCO consumption of the sample to be tested before and after storage.

5. The method for evaluating the storage stability of polyurethane cold patch material based on the correlation between NCO change and strength according to claim 4, characterized in that: The NCO content formula of the cold patch material is: Where W is the content of NCO; V0 is the volume of the standard hydrochloric acid solution consumed in the blank test; V s is the volume of hydrochloric acid standard titration solution consumed during the sample test; C is the concentration of hydrochloric acid standard titration solution; m is the mass of the sample to be tested; The calculation formula of the NCO consumption rate is: Where, Δ NCO％ is the NCO consumption rate; W 存储前 is the NCO content in the sample to be tested before consumption; W 存储后 is the NCO content in the sample to be tested after consumption after storage under different conditions.

6. The method for evaluating the storage stability of polyurethane cold patch material based on the correlation between NCO change and strength according to claim 2, characterized in that: The method of measuring the NCO characteristic infrared peak area change rate of the characteristic peak sample before and after storage by infrared spectroscopy includes: S31, placing the characteristic peak test samples on the Fourier infrared spectrometer in sequence for online detection, and setting the instrument parameters, which include spectral resolution, number of scans, and scanning range; S32, collect the infrared spectrum after online detection by monitoring 2252cm -1 The isocyanate group at 2970 cm -1 Quantitative analysis is performed by tracking the change in the NCO characteristic infrared peak area of ​​the sample to be tested during storage.

7. The method for evaluating the storage stability of polyurethane cold patch material based on the correlation between NCO change and strength according to claim 6, characterized in that: The calculation formula for the NCO characteristic infrared peak area change rate is: Where I1 is 2252cm -1 The characteristic peak of -NCO group is from 2100-2400cm -1 The peak area calculated at the end of storage is the base; 10 2252cm -1 The characteristic peak of -NCO group is from 2100-2400cm -1 The peak area calculated at the start of storage is the base; I2 is 2970cm -1 The characteristic peak of -CH2 group is from 2900-3000cm -1 The peak area calculated at the end of storage is the base; 20 2970cm -1 The characteristic peak of -CH2 group is from 2900-3000cm -1 The peak area calculated at the start of storage is used as the base.

8. The method for evaluating the storage stability of polyurethane cold patch material based on the correlation between NCO change and strength according to claim 2, characterized in that: The Marshall stability of the strength of the sample to be tested before and after storage includes: S41, weighing a preset mass of the strength test sample and placing it in a container, and evenly spraying a preset mass of water to fully mix the strength test sample and the water to obtain a mixture; S42, transferring the mixture to a Marshall test mold, and using a ramming knife to tamp the mold along the periphery and the middle part. After the tamping is completed, the surface of the strength test sample is smoothed; S43, compacting the leveled strength sample using a Marshall electric compactor, and curing the compacted strength sample under a preset temperature condition; S44. Use a Marshall stability tester to measure the Marshall stability of the test sample after curing.

9. The method for evaluating the storage stability of polyurethane cold patch material based on the correlation between NCO change and strength according to claim 2, characterized in that: The correlation model of NCO consumption rate, NCO characteristic infrared peak area change rate and Marshall stability based on the measurement results of various tests includes: S51. Draw a curve showing the relationship between NCO consumption rate and Marshall stability. S52. Draw a curve of the relationship between the rate of change of the NCO characteristic infrared peak area and the Marshall stability; S53. Based on the two relationship curves drawn, a correlation model among the NCO consumption rate, the NCO characteristic infrared peak area change rate and the Marshall stability is established.

10. The method for evaluating the storage stability of polyurethane cold patch material based on the correlation between NCO change and strength according to claim 2, characterized in that: Based on the Marshall stability of the polyurethane cold patch material after storage, the storage stability classification standards are formulated as follows: S61. Test the Marshall stability of the cold patch material sample and classify the storage stability grade according to the strength test value of the Marshall stability; S62. Use the Marshall stability of the cold patch material after storage as an evaluation index to evaluate the storage stability of the polyurethane cold patch material.

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