Method for measuring content of butanediol

Abstract

The invention belongs to the field of testing, and particularly relates to a method for measuring the content of butanediol, which comprises the following steps: carrying out thermal weight loss on a sample to realize effective separation of butanediol from free water and crystal water to obtain three thermal weight loss intervals, and calculating the thermal weight loss contents of a first thermal weight loss interval and a second thermal weight loss interval through a difference value method as the content of butanediol. The method is short in test time, accurate in result and low in test equipment price.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of testing, and particularly relates to a measurement method of butanediol content. BACKGROUND

[0002] Currently, there are three methods for detecting butanediol content. The first method is UV-Vis spectrophotometry, which is based on the strong absorption capacity of the o-diphenol functional group contained in the butanediol molecule in the ultraviolet-visible light region, and the content is determined by detecting the absorbance. The second method is gas chromatography, which is based on the principle of separating the sample through a gas chromatograph and detecting the presence of butanediol in the detector. The third method is high-performance liquid chromatography, which is based on liquid chromatography technology, separates and detects butanediol on a column.

[0003] The UV-Vis spectrophotometry, gas chromatography and high-performance liquid chromatography measure the sample in liquid form. When measuring a powder sample, an extraction liquid is used to extract butanediol from the powder sample, and the extraction time often needs to be 12 hours, so that the measurement period exceeds 12 hours, which cannot meet the timely feedback of butanediol content results. At the same time, the above three methods have expensive testing equipment, so there is an urgent need for a new detection method with relatively low price, accurate measurement results and short testing time. SUMMARY

[0004] The purpose of the present application is to overcome the shortcomings in the prior art and provide a measurement method of butanediol content.

[0005] To achieve the above purpose, the technical solution adopted by the present application is as follows:

[0006] A measurement method of butanediol content, which realizes the effective separation of butanediol from free water and crystal water by thermogravimetry of the sample, obtains three thermogravimetric intervals, and calculates the thermogravimetric content of the first thermogravimetric interval and the second thermogravimetric interval by difference method as the butanediol content.

[0007] Specifically, the following steps are adopted: placing a powder sample in a crucible, and using a thermogravimetric analyzer to perform thermogravimetry on the sample through a multi-pass temperature rising program.

[0008] The multi-pass temperature rising program of thermogravimetry has a temperature rising rate of 1-50℃ / min, preferably 5-15℃ / min.

[0009] The first temperature rising program rises from the initial temperature to 80-100℃, preferably 90-100℃, and performs heat preservation to ensure that the weight loss curve is flat; preferably, the heat preservation time is 3-15min.

[0010] The initial temperature is 10-50℃, preferably 25-40℃.

[0011] The second temperature rising procedure is from the first holding temperature to 140-160℃, preferably 140℃, and holding to ensure the weight loss curve to be flat, preferably, the holding time is 3-15 min.

[0012] The third temperature rising procedure is from the second holding temperature to 180-220℃, preferably 190℃.

[0013] The third temperature rising procedure is from the second holding temperature to 180-220℃, preferably 190℃.

[0014] The judging standard of the flat weight loss curve is that the weight loss percentage of the sample in a certain time is 0-0.01%, wherein the certain time is 0.5-10 min, preferably 1-3 min.

[0015] Preferably, the flat weight loss is automatically judged by the program setting, and the temperature rising procedure is automatically transferred to the next stage.

[0016] The butanediol is one of 1,2 butanediol, 1,3 butanediol or 1,4 butanediol or a mixture.

[0017] The sample is a powdery sample, preferably, the weight of the powdery sample is 50-2000 mg, preferably 500-2000 mg.

[0018] Compared with the prior art, the present application has the following advantages:

[0019] The first advantage of the present application is short test time, the test time is 20-60 min, and the specific implementation method is as follows: one is to set a fixed two-stage temperature rising procedure to obtain the basic time of the temperature rising procedure, and the other is to automatically judge the flat weight loss by the program setting, and the temperature rising procedure is automatically transferred to effectively shorten the test time.

[0020] The second advantage of the present application is accurate test result, the difference percentage between the first flat weight loss percentage and the second flat weight loss percentage represents the butanediol content percentage, and the test accuracy can be controlled within ±0.01%.

[0021] The third advantage of the present application is low price of the test equipment, the equipment used in the method is a thermal gravimetric analyzer, and the weighing accuracy should be within ±0.02 mg, and some domestic thermal gravimetric analyzers can meet the requirements, and the price of the domestic thermal gravimetric analyzer is much lower than that of other test equipment. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The sample weight loss curve obtained by the butanediol content measurement method of the embodiment 1 of the present application;

[0023] Figure 2MSA verification chart for test results of Example 1 of the present application;

[0024] Figure 3 Two-sample t-test chart for test results of Example 1 of the present application. DETAILED DESCRIPTION

[0025] In order to enable a person skilled in the art to better understand the technical solutions of the present application, the present application will be further described in detail below in combination with the drawings and the best mode.

[0026] Example 1:

[0027] A method for measuring the content of butanediol, by thermogravimetry of the sample, realizing the effective separation of butanediol from free water and crystal water, obtaining three thermogravimetric intervals, and calculating the thermogravimetric content of the first thermogravimetric interval and the second thermogravimetric interval by difference method as the content of butanediol.

[0028] Specifically, the following steps are used: 1000 mg of powder sample is placed in a crucible, and thermogravimetry of the sample is performed by using a thermogravimetric analyzer through a multi-pass temperature rising program. The weighing accuracy of the thermogravimetric analyzer should be within ±0.02 mg, preferably within ±0.01 mg; the temperature accuracy of the thermogravimetric analyzer should be within ±8℃, preferably within ±3℃;

[0029] The heating rate of the multi-pass temperature rising program of thermogravimetry is 1-50℃ / min, which can be specifically 1℃ / min, 5℃ / min, 10℃ / min, 15℃ / min, 25℃ / min, 50℃ / min, preferably 5-15℃ / min, and in this embodiment, 10℃ / min is used as a preferred example.

[0030] The first temperature rising program is from the initial temperature to 80-100℃, which can be specifically 80℃, 90℃, 95℃, 100℃; preferably 90-100℃; in this application, 100℃ is used as a preferred example; and the temperature is kept constant to ensure that the weight loss curve is flat;

[0031] Preferably, the holding time is 3-15 min, which can be specifically 3 min, 7 min, 10 min, 15 min, and in this application, 7 min is used as a preferred example.

[0032] The initial temperature is 10-50℃, which can be specifically 10℃, 20℃, 250℃, 30℃, 40℃, 50℃, preferably 25-40℃, and in this application, 40℃ is used as a preferred example.

[0033] The second temperature rising procedure is from the first holding temperature to 140-160°C, specifically, 140°C, 150°C, 160°C, preferably 140°C; in this application, 140°C is taken as the preferred example. And holding is performed to ensure the weight loss curve to be flat;

[0034] Preferably, the holding time is 3-15 min. Specifically, 3 min, 7 min, 10 min, 15 min, in this application, 7 min is taken as the preferred example.

[0035] The third temperature rising procedure requires the temperature to be raised from the second holding temperature to 180-220°C, specifically, 180°C, 190°C, 200°C, 210°C, 220°C; preferably, 190-210°C; in this application, 200°C is taken as the preferred example, and holding is performed to ensure the weight loss curve to be flat;

[0036] Preferably, the holding time is 3-15 min, specifically, 3 min, 7 min, 10 min, 15 min, in this application, 10 min is taken as the preferred example.

[0037] The judgment standard for the weight loss curve to be flat is that the weight loss percentage of the sample within a certain time is 0-0.01%, wherein the certain time is 0.5-10 min, specifically, 0.5 min, 1 min, 2 min, 3 min, 5 min, 10 min; preferably, 1-3 min.

[0038] Figure 1 For the weight loss curve obtained by using the multi-pass temperature rising thermogravimetric method, the temperature rising procedure of this embodiment is 40°C (initial temperature)→100°C (first holding temperature, 7 min)→140°C (second holding temperature, 7 min)→200°C (third holding temperature, 10 min), the whole temperature rising rate is 10°C / min, and the test time is 40 min.

[0039] The sample used is the negative electrode powder scraped from the lithium battery negative electrode sheet, and the equipment used is a domestic thermogravimetric analyzer. The difference interval between the first flat stage and the second flat stage is the weight loss interval of only butanediol, and the difference between the first flat weight loss percentage and the second flat weight loss percentage is the butanediol content percentage.

[0040] Table 1 is the butanediol content obtained by using a thermogravimetric analyzer through a multi-pass temperature rising thermogravimetric method, using 2 operators A and B, 6 butanediol content gradients, and repeating the measurement 2 times; the test results in Table 1 are used for MSA verification, and the results are shown in Table 2. Figure 2 The MSA verification results show that the measurement system has good repeatability, reproducibility and distinguishability;

[0041] Table 1

[0042]

[0043] Since the butanediol content test has irreversibility and the butanediol content in the electrode sheet has large difference in distribution, the extraction method and the thermogravimetric method test data are considered to be subjected to two-sample T test, the extraction method and the thermogravimetric method test values are shown in Table 2, the two-sample t test is performed on the test results, as shown in Table 3, the P value = 0.873 > 0.05, it is considered that there is no significant difference between the mean values of the butanediol content tested by the extraction method and the thermogravimetric method. Figure 3

[0044] Table 2

[0045]

[0046] In summary, the first great advantage of the present application is that the test time is short, and the test time required is 20 min to 60 min, and the specific implementation method has two, one is to obtain the basic time of the temperature rising process by setting a fixed two-stage temperature rising program, and the other is to effectively shorten the test time by automatically determining the thermal weight loss flat through program setting, and realizing the automatic transfer of the temperature rising process.

[0047] The second great advantage of the present application is that the test result is accurate, and the difference percentage between the first-stage flat weight loss percentage and the second-stage flat weight loss percentage represents the butanediol content percentage, and the test accuracy can be controlled within ± 0.01%.

[0048] The third great advantage of the present application is that the test equipment price is low, and the equipment used in the method is a thermogravimetric analyzer, which requires a weighing accuracy within ± 0.02 mg, and some domestic thermogravimetric analyzers can meet the requirements, and the price of the domestic thermogravimetric analyzer is much lower than that of other test method equipment.

[0049] The above only describes the preferred embodiments of the present application, and it should be noted that for ordinary skilled persons in the technical field, some improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.​

Claims

1. A method for measuring butanediol content, characterized in that, By performing thermogravimetric analysis on the sample, butanediol was effectively separated from free water and water of crystallization, resulting in three thermogravimetric analysis intervals. The thermogravimetric analysis content of the first and second thermogravimetric analysis intervals was calculated using the difference method, which is the butanediol content.

2. The method for measuring butanediol content according to claim 1, characterized in that, The specific steps are as follows: Place the powder sample in a crucible, and use a thermogravimetric analyzer to measure the thermal weight loss of the sample through a multi-stage heating program.

3. The method for measuring butanediol content according to claim 2, characterized in that, The heating rate of the multi-stage heating program for thermogravimetric analysis is 1–50 °C / min, preferably 5–15 °C / min.

4. The method for measuring butanediol content according to claim 2, characterized in that, The first stage of the heating process raises the temperature from the initial temperature to 80℃~100℃, preferably 90℃~100℃; Insulation is performed to ensure the weight loss curve remains flat; preferably, the insulation time is 3 to 15 minutes.

5. The method for measuring butanediol content according to claim 4, characterized in that, The initial temperature is 10℃~50℃, preferably 25~40℃.

6. The method for measuring butanediol content according to claim 4, characterized in that, The second stage of the heating process raises the temperature from the first stage of heat preservation to 140℃~160℃, preferably 140℃; Insulation is performed to ensure the weight loss curve remains flat; preferably, the insulation time is 3 to 15 minutes.

7. The method for measuring butanediol content according to claim 6, characterized in that, The third stage of the heating process requires the temperature to be raised from the second stage of the heat preservation temperature to 180℃~220℃, preferably 190℃~210℃; Insulation is performed to ensure the weight loss curve remains flat; preferably, the insulation time is 3 to 15 minutes.

8. The method for measuring the butanediol content according to any one of claims 4-7, characterized in that, The criterion for judging the flattening of the weight loss curve is that the percentage of weight loss of the sample is 0-0.01% within a certain period of time, of which the certain period of time is 0.5-10 min, preferably 1-3 min; Preferably, the program automatically determines when the thermal weight loss level is reached, thus automatically transferring the heating process to the next stage.

9. The method for measuring butanediol content according to claim 1, characterized in that, The butanediol mentioned is one or a mixture of 1,2-butanediol, 1,3-butanediol, or 1,4-butanediol.

10. The method for measuring butanediol content according to claim 2, characterized in that, The sample is a powder sample.

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