Method for measuring isocyanate conversion rate in reaction process of double-component polyurethane high polymer slurry

Abstract

The invention discloses a method for measuring the isocyanate conversion rate in the reaction process of double-component polyurethane high polymer slurry, which comprises the following steps: mixing a component A and a component B, and starting timing after uniformly mixing, the component A comprising isocyanate; the method comprises the following steps: sampling at a to-be-detected time point by using a pre-cooled sampler, putting a sample in a low-temperature environment, adding an organic solvent, uniformly mixing, standing and layering the mixed solution, and collecting an organic phase at the lower layer; respectively carrying out infrared spectroscopic analysis on the organic phase by using an infrared spectrometer, comparing relative changes of an isocyanate absorption peak and an internal standard absorption peak at different time points, and quantitatively calculating the conversion rate of the isocyanate in the reaction process; the problems that a traditional titration method is tedious in operation, prone to being influenced by personal errors, prone to being interfered by side reactions and the like are solved, and the measurement result is more accurate; meanwhile, the method disclosed by the invention is non-destructive detection, so that the consumption of the sample is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of polyurethane polymers, and in particular to a method for determining the isocyanate conversion rate in a two-component polyurethane polymer slurry reaction process. Background Art

[0002] In recent years, polymer grouting, as a new type of engineering repair technology, has been widely used in infrastructure repair projects due to its advantages such as fast expansion, high early strength, waterproofness, durability, and environmental protection. For example, in water hazard prevention, foundation reinforcement, road maintenance, etc. in underground projects such as mines and tunnels, polymer grouting has become a distinctive development direction in the field of geotechnical engineering.

[0003] The main components of polymer slurry include isocyanate, polyol, foaming agent and catalyst, etc. These components mainly constitute two raw materials A and B. Among them, A is mainly composed of isocyanate, while B contains polyol, catalyst, foaming agent, foam stabilizer, etc. When A and B are fully stirred and mixed, gel reaction and foaming reaction mainly occur. At the beginning of the reaction, the slurry is a reddish brown viscous liquid. As the reaction proceeds, a large number of bubble nuclei are gradually generated, the bubbles rapidly increase in size, and the volume expands, and finally solidifies to form a high molecular solid polymer with a certain strength.

[0004] In this reaction process, the isocyanate conversion rate directly affects the curing rate and final performance of the polyurethane slurry. The physical properties of the polyurethane slurry, such as hardness, viscoelasticity, durability and water resistance, mainly depend on the degree of reaction between isocyanate and polyol in the slurry. Therefore, accurate determination of the isocyanate conversion rate is the key to ensuring that the slurry achieves the expected reaction efficiency during the construction process, thereby ensuring the final material performance and construction quality. In addition, through the study of the isocyanate conversion rate, the key factors affecting the slurry reaction, such as reaction temperature, catalyst type, component ratio, etc., can be found. These data can be used to optimize the formulation of the polyurethane slurry, improve its reaction rate and curing characteristics, and make it more suitable for specific engineering needs.

[0005] At present, the commonly used measurement method is titration, which has relatively low measurement accuracy and is easily interfered by side reactions or other chemical substances. In addition, titration is a destructive test, and each measurement consumes a large amount of sample, resulting in sample waste and increased experimental costs. Secondly, the operation is complicated and susceptible to human errors, which limits the application of this method in more precise occasions. Summary of the invention

[0006] The purpose of the invention is to provide a method for determining the isocyanate conversion rate during the reaction of a two-component polyurethane polymer slurry, thereby solving the problem of the insufficiency of the prior art in measuring the isocyanate conversion rate by titration.

[0007] The present invention is achieved by a method for determining the isocyanate conversion rate during a two-component polyurethane polymer slurry reaction, comprising the following steps:

[0008] S1, mixing component A, component B and a calibration substance, and starting timing after the mixture is evenly mixed, wherein component A includes isocyanate;

[0009] S2. Use a pre-cooled sampler to take samples at different time points, place the samples in a low temperature environment, add an organic solvent and mix them evenly, let the mixture stand and separate, and collect the organic phase at the lower layer;

[0010] S3. Use an infrared spectrometer to perform infrared spectroscopy analysis on the organic phase, compare the relative changes of the isocyanate absorption peak and the internal standard absorption peak at different time points, and quantitatively calculate the conversion rate of isocyanate during the reaction.

[0011] The present invention mixes and reacts component A and component B, takes samples at different time points during the reaction, collects samples at different time points and uses infrared spectroscopy to perform quantitative analysis on characteristic absorption peaks of isocyanate (NCO) groups in the samples, uses the CH stretching vibration peak of isocyanate methylene (-CH2-) as an internal standard characteristic peak during the analysis, eliminates the influence of interference factors on the isocyanate conversion rate, and does not add new additives, thereby solving the problems of cumbersome operation, susceptibility to human error, and interference from side reactions in traditional titration methods, and making the measurement results more accurate; meanwhile, the method of the present invention is non-destructive detection, and avoids the consumption of samples.

[0012] A further technical solution of the present invention is: the sampler is an aluminum sampling cup, and the aluminum sampling cup has excellent thermal conductivity. Using a pre-cooled aluminum sampling cup can quickly cool the sample. It is difficult for the polyurethane polymer slurry to react at low temperature. The sample is then placed in an ice-water mixture to maintain a low temperature, further inhibiting its reaction.

[0013] A further technical solution of the present invention is: in the step S2, the organic phase is isocyanate, and infrared spectroscopy is used to analyze the relative change of characteristic absorption peaks.

[0014] A further technical solution of the present invention is: in step S3, the conversion rate of isocyanate is calculated according to formula 1:

[0015]

[0016] Among them, A NCO,t and are the isocyanate absorption peak areas at a certain time t and the initial time t0 of the reaction, A C-H,t and are the internal standard absorption peak areas at a certain reaction time t and the initial time t0 respectively.

[0017] A further technical solution of the present invention is: the initial time t0 is the time when timing starts in step S1.

[0018] A further technical solution of the present invention is that the value range of the certain moment t does not exceed 90s.

[0019] A further technical solution of the present invention is: in step S1, the volume ratio of component A:component B is 1:1.

[0020] A further technical solution of the present invention is: the internal standard absorption peak is the CH stretching vibration peak of the reactant isocyanate methylene (-CH2-); and the organic solvent includes dichloromethane.

[0021] Dichloromethane has a weak polarity and good compatibility with isocyanates. It can efficiently extract isocyanates even at low temperatures, but it is insoluble in water or polyols. Dichloromethane is a relatively inert organic solvent. Therefore, during the extraction process, it will not produce side reactions with water or polyols in component B, ensuring the chemical stability of the system. Dichloromethane has a high density and will be located in the lower layer of the separatory funnel when standing and stratifying.

[0022] The internal standard absorption peak is the CH stretching vibration peak of the reactant isocyanate methylene (-CH2-), located at 2923 cm -1 The peak intensity is stable and far away from the characteristic absorption peak of isocyanate at 2270 cm -1 , can be well distinguished; not only will it not react with other substances in the system, but it will also not overlap with the characteristic absorption peaks of other reactants, so it will not be interfered by other substances in the reaction.

[0023] The characteristic absorption peak of isocyanate in step S3 is located at 2270 cm -1 .

[0024] A further technical solution of the present invention is that the volume ratio of the organic solvent to the sample is (2-3):1.

[0025] A further technical solution of the present invention is: the low temperature environment has a temperature of 0°C to 4°C.

[0026] A further technical solution of the present invention is: the infrared spectrometer is a Fourier transform infrared spectrometer.

[0027] A further technical solution of the present invention is that component B includes polyol, water, a physical foaming agent, a catalyst and an auxiliary agent.

[0028] The beneficial effects of the present invention are as follows: the present invention mixes and reacts component A and component B, samples are taken at different time points during the reaction, samples are collected at different time points and infrared spectroscopy is used to perform quantitative analysis on characteristic absorption peaks of isocyanate (NCO) groups in the samples, during the analysis, the CH stretching vibration peak of isocyanate methylene (-CH2-) is used as an internal standard characteristic peak, the influence of interference factors on the isocyanate conversion rate is eliminated, and no new additives are added, thereby solving the problems of cumbersome operation, susceptibility to human errors and interference from side reactions of the traditional titration method, and the measurement result is more accurate; at the same time, the method of the present invention is non-destructive detection, and the consumption of samples is avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a flow chart of a method for determining the isocyanate conversion rate in a two-component polyurethane polymer slurry reaction process provided by the present invention;

[0030] Figure 2 It is the infrared spectra of Embodiment 1 to Embodiment 4 provided by the present invention;

[0031] Figure 3 It is a schematic diagram of the isocyanate conversion rate in Examples 1 to 4 provided by the present invention. DETAILED DESCRIPTION

[0032] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0033] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any modification of the structure, change of the proportion relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. The change or adjustment of their relative relationship should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0034] Embodiment 1:

[0035] Figure 1-3A method for determining the isocyanate conversion rate during a two-component polyurethane polymer slurry reaction is shown, comprising the following steps:

[0036] S1. Add 20 mL of component A and 20 mL of component B into an insulated reaction vessel, stir for 5 seconds and then start timing. When the timing reaches 0 seconds and 12 seconds, use a pre-cooled aluminum sampling cup to take samples, and quickly place the samples in an ice-water mixture at 0°C to keep the temperature low.

[0037] Among them, component A is isocyanate, and component B mainly includes polyol, water, physical foaming agent, catalyst and additives. After mixing, the following gelation reaction and foaming reaction mainly occur:

[0038]

[0039] S2. Add dichloromethane twice the volume of the sample into the sampling cup and stir thoroughly to mix; transfer the mixture to a separatory funnel, let it stand until it separates into layers, and collect the dichloromethane organic phase at the lower layer;

[0040] S3. Use Fourier transform infrared spectrometer (FTIR) to perform infrared spectroscopy analysis on the dichloromethane organic phase to measure the characteristic absorption peak of the isocyanate (NCO) group; the dichloromethane organic phase is isocyanate; by comparing the relative changes of the isocyanate absorption peak at 0s and 12s with the internal standard absorption peak, the conversion rate of isocyanate during the reaction process is quantitatively calculated.

[0041] In this embodiment, the organic phase in step S3 is isocyanate, and the relative change of the characteristic absorption peak is analyzed by infrared spectroscopy, and the conversion rate of isocyanate is calculated according to the following formula:

[0042]

[0043] Among them, A NCO,t and are the isocyanate absorption peak areas at a certain time t and the initial time t0 of the reaction, A C-H,t and They are the internal standard absorption peak areas at a certain time t and the initial time t0 of the reaction, respectively. Where t is 12s and t0 is 0s.

[0044] The characteristic absorption peak of isocyanate is located at 2270 cm -1 The internal standard absorption peak is the CH stretching vibration peak of the reactant isocyanate methylene (-CH2-), located at 2923 cm -1 far from the characteristic absorption peak of isocyanate at 2270 cm -1 , can be distinguished well.

[0045] In this embodiment, if Figure 2As shown, the characteristic absorption peak integral area of ​​isocyanate at 0 seconds is 33.295, and the characteristic peak area of ​​isocyanate at 12 seconds is 30.258. The conversion rate of isocyanate calculated according to Formula 1 is 9.06%.

[0046] Embodiment 2:

[0047] Figure 1-3 A method for determining the isocyanate conversion rate during a two-component polyurethane polymer slurry reaction is shown, comprising the following steps:

[0048] S1. Add 20 mL of component A and 20 mL of component B into an insulated reaction vessel, stir for 5 seconds and then start timing. When the timing reaches 0 seconds and 24 seconds, use a pre-cooled aluminum sampling cup to take samples, and quickly place the samples in an ice-water mixture at 0°C to keep the temperature low.

[0049] Among them, component A is isocyanate, and component B mainly includes polyol, water, physical foaming agent, catalyst and additives. After mixing, the following gelation reaction and foaming reaction mainly occur:

[0050]

[0051] S2. Add dichloromethane in a volume three times the volume of the sample into the sampling cup and stir thoroughly to mix; transfer the mixture to a separatory funnel, let it stand until it separates into layers, and collect the dichloromethane organic phase at the lower layer;

[0052] S3. Use Fourier transform infrared spectrometer (FTIR) to perform infrared spectroscopy analysis on the dichloromethane organic phase to measure the characteristic absorption peak of the isocyanate (NCO) group. The dichloromethane organic phase is isocyanate; by comparing the relative changes of the isocyanate absorption peak at 0s and 24s with the internal standard absorption peak, the conversion rate of isocyanate during the reaction is quantitatively calculated.

[0053] In this embodiment, the organic phase in step S3 includes isocyanate, and the relative change of the characteristic absorption peak is analyzed by infrared spectroscopy, and the conversion rate of isocyanate is calculated according to the following formula:

[0054]

[0055] Among them, A NCO,t and are the isocyanate absorption peak areas at a certain time t and the initial time t0 of the reaction, A C-H,t and They are the internal standard absorption peak areas at a certain time t and the initial time t0 of the reaction, where t is 24s and t0 is 0s.

[0056] The characteristic absorption peak of isocyanate is located at 2270 cm -1The internal standard absorption peak is the CH stretching vibration peak of the reactant isocyanate methylene (-CH2-), located at 2923 cm -1 far from the characteristic absorption peak of isocyanate at 2270 cm -1 , can be distinguished well.

[0057] In this embodiment, if Figure 2 As shown, the characteristic absorption peak area of ​​isocyanate at 0 seconds is 33.295, and the characteristic peak area of ​​isocyanate at 24 seconds is 26.125. The conversion rate of isocyanate calculated according to Formula 1 is 21.465%.

[0058] Embodiment three:

[0059] Figure 1-3 A method for determining the isocyanate conversion rate during a two-component polyurethane polymer slurry reaction is shown, comprising the following steps:

[0060] S1. Add 20 mL of component A and 20 mL of component B into an insulated reaction vessel, stir for 5 seconds and then start timing. When the timing reaches 0 seconds and 36 seconds, use a pre-cooled aluminum sampling cup to take samples, and quickly place the samples in an ice-water mixture at 0°C to keep the temperature low.

[0061] Among them, component A is isocyanate, and component B mainly includes polyol, water, physical foaming agent, catalyst and additives. After mixing, the following gelation reaction and foaming reaction mainly occur:

[0062]

[0063] S2. Add dichloromethane in a volume three times the volume of the sample into the sampling cup and stir thoroughly to mix; transfer the mixture to a separatory funnel, let it stand until it separates into layers, and collect the dichloromethane organic phase at the lower layer;

[0064] S3. Use Fourier transform infrared spectrometer (FTIR) to perform infrared spectroscopy analysis on the dichloromethane organic phase to measure the characteristic absorption peak of the isocyanate (NCO) group. The dichloromethane organic phase is isocyanate; by comparing the relative changes of the isocyanate absorption peak at 0s and 36s with the absorption peak of the internal standard, the conversion rate of isocyanate during the reaction is quantitatively calculated.

[0065] In this embodiment, the organic phase in step S3 includes isocyanate, and the relative change of the characteristic absorption peak is analyzed by infrared spectroscopy, and the conversion rate of isocyanate is calculated according to the following formula:

[0066]

[0067] Among them, A NCO,t and are the isocyanate absorption peak areas at a certain time t and the initial time t0 of the reaction, A C-H,t and They are the internal standard absorption peak areas at a certain time t and the initial time t0 of the reaction, where t is 36s and t0 is 0s.

[0068] The characteristic absorption peak of isocyanate is located at 2270 cm -1 The internal standard absorption peak is the CH stretching vibration peak of the reactant isocyanate methylene (-CH2-), located at 2923 cm -1 far from the characteristic absorption peak of isocyanate at 2270 cm -1 , can be well distinguished. In this embodiment, Figure 2 As shown, the characteristic absorption peak area of ​​isocyanate at 0 seconds is 33.295, and the characteristic peak area of ​​isocyanate at 36 seconds is 21.106. The conversion rate of isocyanate calculated according to Formula 1 is 36.543%.

[0069] Embodiment 4:

[0070] Figure 1-3 A method for determining the isocyanate conversion rate during a two-component polyurethane polymer slurry reaction is shown, comprising the following steps:

[0071] S1. Add 20 mL of component A and 20 mL of component B to an insulated reaction vessel, stir for 5 seconds and then start timing. When the timing reaches 0 seconds and 48 seconds, use a pre-cooled aluminum sampling cup to take samples, and quickly place the samples in an ice-water mixture at 0°C to keep the temperature low.

[0072] Among them, component A is isocyanate, and component B mainly includes polyol, water, physical foaming agent, catalyst and additives. After mixing, the following gelation reaction and foaming reaction mainly occur:

[0073]

[0074] S2. Add dichloromethane in a volume three times the volume of the sample into the sampling cup and stir thoroughly to mix; transfer the mixture to a separatory funnel, let it stand until it separates into layers, and collect the dichloromethane organic phase at the lower layer;

[0075] S3. Use Fourier transform infrared spectrometer (FTIR) to perform infrared spectroscopy analysis on the dichloromethane organic phase to measure the characteristic absorption peak of the isocyanate (NCO) group. The dichloromethane organic phase is isocyanate; by comparing the relative changes of the isocyanate absorption peak at 0s and 48s with the absorption peak of the internal standard, the conversion rate of isocyanate during the reaction is quantitatively calculated.

[0076] In this embodiment, the organic phase in step S3 includes isocyanate, and the relative change of the characteristic absorption peak is analyzed by infrared spectroscopy, and the conversion rate of isocyanate is calculated according to the following formula:

[0077]

[0078] Among them, A NCO,t and are the isocyanate absorption peak areas at a certain time t and the initial time t0 of the reaction, A C-H,t and They are the internal standard absorption peak areas at a certain time t and the initial time t0 of the reaction, where t is 48s and t0 is 0s.

[0079] The characteristic absorption peak of isocyanate is located at 2270 cm -1 The internal standard absorption peak is the CH stretching vibration peak of the reactant isocyanate methylene (-CH2-), located at 2923 cm -1 far from the characteristic absorption peak of isocyanate at 2270 cm -1 , can be distinguished well.

[0080] In this embodiment, if Figure 2 As shown, the characteristic absorption peak area of ​​isocyanate at 0 seconds is 33.295, and the characteristic peak area of ​​isocyanate at 48 seconds is 16.721. The conversion rate of isocyanate calculated according to Formula 1 is 49.151%.

[0081] The present invention collects samples at a specified time point using a precooling sampler, and quickly places the samples in a low temperature environment to maintain a low temperature to prevent the reaction from continuing, then adds an organic solvent to the samples for extraction, collects the separated organic phase, collects samples at different time points, and uses Fourier transform infrared spectroscopy (FTIR) to quantitatively analyze the characteristic absorption peak of the isocyanate (NCO) group, thereby solving the problems of the traditional titration method being cumbersome to operate, being susceptible to human error, and being interfered by side reactions, and the measurement results are more accurate. In addition, the present method can realize non-destructive detection, avoids the consumption of samples, and can monitor the conversion rate of isocyanate in real time, and has high stability and reliability.

[0082] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for determining the isocyanate conversion rate during a two-component polyurethane polymer slurry reaction, characterized in that: The following steps are involved: S1, mixing component A and component B, and starting timing after the mixture is evenly mixed, wherein component A includes isocyanate; S2. Use a pre-cooled sampler to take samples at different time points, place the samples in a low temperature environment, add an organic solvent and mix them evenly, let the mixture stand and separate, and collect the organic phase at the lower layer; S3. Use an infrared spectrometer to perform infrared spectroscopy analysis on the organic phase, compare the relative changes of the isocyanate absorption peak and the internal standard absorption peak at different time points, and quantitatively calculate the conversion rate of isocyanate during the reaction.

2. The method for determining the isocyanate conversion rate during the reaction of a two-component polyurethane polymer slurry according to claim 1, characterized in that: In step S3, the conversion rate of isocyanate is calculated according to formula 1: Among them, A NCO,t and are the isocyanate absorption peak areas at a certain time t and the initial time t0 of the reaction, A C-H,t and are the internal standard absorption peak areas at a certain reaction time t and the initial time t0 respectively.

3. The method for determining the isocyanate conversion rate during the reaction of a two-component polyurethane polymer slurry according to claim 2, characterized in that: The initial time t0 is the time when timing starts in step S1.

4. The method for determining the isocyanate conversion rate during the reaction of a two-component polyurethane polymer slurry according to claim 2, characterized in that: The value range of the certain moment t does not exceed 90s.

5. The method for determining the isocyanate conversion rate during the reaction of a two-component polyurethane polymer slurry according to claim 1, characterized in that: In the step S1, the volume ratio of component A:component B is 1:

1.

6. The method for determining the isocyanate conversion rate during the reaction of a two-component polyurethane polymer slurry according to claim 1, characterized in that: The internal standard absorption peak is the CH stretching vibration peak of the reactant isocyanate methylene (-CH2-); the organic solvent includes dichloromethane.

7. The method for determining the isocyanate conversion rate during a two-component polyurethane polymer slurry reaction according to claim 1, characterized in that: The volume ratio of the organic solvent to the sample is (2-3):

1.

8. The method for determining the isocyanate conversion rate during a two-component polyurethane polymer slurry reaction according to claim 1, characterized in that: The low temperature environment has a temperature of 0°C to 4°C.

9. The method for determining the isocyanate conversion rate during the reaction of a two-component polyurethane polymer slurry according to claim 1, characterized in that: The infrared spectrometer is a Fourier transform infrared spectrometer.

10. The method for determining the isocyanate conversion rate during the reaction of a two-component polyurethane polymer slurry according to claim 1, characterized in that: Component B includes polyol, water, physical foaming agent, catalyst and additives.

Images