Method for measuring softening temperature of rosin

Abstract

The invention provides a method for measuring softening temperature of rosin. The method comprises the following steps: 1) setting a target temperature range R1-R2, and measuring first nuclear magnetic semaphores, R1lt, of rosin samples at different test temperatures in the target temperature range R1-R2 by using a nuclear magnetic resonance analyzer; r2; 2) performing temperature correction on the first nuclear magnetic semaphore to obtain a second nuclear magnetic semaphore; 3) establishing a first curve between the second nuclear magnetic semaphore and different test temperatures; 4) performing derivative solution on the first curve so as to establish a second curve in which the change rate of the second nuclear magnetic semaphore changes along with different test temperatures; and 5) acquiring the softening temperature of the rosin sample according to the first curve and the second curve. According to the method for measuring the softening temperature of the rosin, the softening temperature of the rosin can be conveniently and accurately measured. And in the measurement process, the influence of factors such as operators, environmental conditions, instruments and equipment, detection parameters and the like in the detection process can be reduced.

Description

Technical Field

[0001] The invention relates to a method for measuring the softening temperature of rosin, and belongs to the technical field of rosin processing and utilization. Background Art

[0002] Rosin is processed from pine resin and is a renewable natural organic resin with high density, low relative molecular mass and no fixed melting point. Rosin has unique physical and chemical properties and is an indispensable chemical raw material. As the ambient temperature rises, rosin will gradually soften from solid state and finally become liquid. The softening temperature of rosin is one of the important indicators that directly and accurately evaluates the quality of rosin and affects the processing conditions and product quality of rosin. It is generally believed that the higher the softening temperature, the better the quality of rosin.

[0003] The softening point test of rosin usually adopts the ring and ball method, which generally includes: melting, sample preparation, cooling, testing and other steps. The steps are cumbersome, affected by human operation and conditions, and the test requires specific instruments. In addition, the softening point test of rosin can also use a specific rosin softening tester to measure the softening temperature of rosin. The instrument uses the principle of heat conduction to measure the softening point of rosin under certain conditions. In the experiment, the sampled rosin is placed in a cup filled with water of a predetermined height, supported on a sample rack, placed in the tester, and the water temperature is heated until the rosin softens, and water will leak out from the bottom of the rosin. When water flows out of the rosin, it indicates that the rosin has softened. The temperature at this time is recorded. This temperature is the softening temperature of the rosin in this reagent. However, even if a specific instrument is used, the softening temperature of rosin is still inaccurate due to the influence of operators and environmental conditions.

[0004] Therefore, it is necessary to develop a simple and accurate measurement method to minimize the impact of factors such as operators, environmental conditions, instruments and equipment, and detection parameters during the detection process, which has become a technical problem that needs to be solved urgently. Summary of the invention

[0005] Problem that the invention aims to solve

[0006] In view of the technical problems existing in the prior art, the present invention first provides a simple and accurate method for measuring the softening temperature of rosin, which can reduce the influence of factors such as operators, environmental conditions, instruments and equipment, and detection parameters during the detection process. The method for measuring the softening temperature of rosin of the present invention can conveniently and accurately measure the softening temperature of rosin.

[0007] Solutions for solving problems

[0008] The present invention provides a method for measuring the softening temperature of rosin, which comprises the following steps:

[0009] 1) Setting a target temperature range R1-R2, using a nuclear magnetic resonance analyzer to measure the first nuclear magnetic signal of the rosin sample at different test temperatures in the target temperature range R1-R2, wherein R1 <R2;

[0010] 2) performing temperature correction on the first nuclear magnetic signal to obtain a second nuclear magnetic signal;

[0011] 3) establishing a first curve between the second nuclear magnetic signal and the different test temperatures;

[0012] 4) solving the derivative of the first curve to establish a second curve showing the rate of change of the second nuclear magnetic signal as the test temperature changes;

[0013] 5) Obtaining the softening temperature of the rosin sample according to the first curve and the second curve.

[0014] According to the method of the present invention, the nuclear magnetic resonance analyzer is a low-field nuclear magnetic resonance analyzer coupled with a temperature control system.

[0015] According to the method of the present invention, before detecting the first nuclear magnetic signal, the method further includes the following steps:

[0016] Using a standard oil sample and a free induction decay pulse sequence, the center frequency and pulse width of the nuclear magnetic resonance analyzer are calibrated;

[0017] Heating the rosin sample to obtain different test temperatures within a target temperature range R1 to R2 of the rosin sample;

[0018] After the rosin samples reach different test temperatures, they are kept warm and the first nuclear magnetic signal quantity detection is performed respectively.

[0019] According to the method of the present invention, the target temperature range R1-R2 is 25-150°C; the temperature step between two adjacent test temperatures is 0.2-20°C; and the insulation time is 5-30 minutes.

[0020] According to the method described in the present invention, the parameters for detecting the first nuclear magnetic signal quantity include: a repeated scanning time interval of 500 to 5000 ms; a 180° pulse number of 3000 to 15000; a 180° pulse echo time of 0.1 to 0.6 ms, and a repeated scanning number of 16 to 256 times.

[0021] According to the method of the present invention, the temperature correction is performed according to the following formula (1):

[0022] I ac =I bc ×(Tj / (T + 273.15) r (1) (T + 273.15)

[0023] In the formula

[0024] I ac is the second nuclear magnetic signal quantity, a.u.;

[0025] I bc is the first nuclear magnetic signal quantity, a.u.;

[0026] T j is the different test temperatures within the target temperature range R1 - R2, °C;

[0027] T r is the reference temperature, and T r ≥ 0 °C.

[0028] According to the method of the present invention, wherein, T r is 25 - 150 °C.

[0029] According to the method of the present invention, wherein, based on the second curve, the transition temperature corresponding to when the change rate of the second nuclear magnetic signal quantity of the rosin sample reaches the maximum value is obtained, and the transition temperature is the softening temperature of the rosin sample.

[0030] According to the method of the present invention, wherein, according to the set target temperature range R3 - R4, steps 1) - 5) are repeated to obtain the softening temperature of the rosin sample; wherein, R3 > R1, R4 < R2, and R3 < R4.

[0031] According to the method of the present invention, wherein, according to the set target temperature range R5 - R6, the steps 1) - 5) are repeated to obtain the softening temperature of the rosin sample; wherein, R5 > R3, R6 < R4, and R5 < R6.

[0032] Effects of the invention

[0033] The method for measuring the softening temperature of rosin of the present invention can conveniently and accurately determine the softening temperature of rosin. And during the measurement process, the influence of factors such as process operators, environmental conditions, instrument equipment, and detection parameters can be reduced. Brief description of the drawings

[0034] Figure 1 Shows the first curve and the second curve of three groups of different target temperature ranges of the rosin sample A.

[0035] Figure 2 Shows the first curve and the second curve of three groups of different target temperature ranges of the rosin sample B.

[0036] Figure 3 A first curve and a second curve for the target temperature range of rosin sample C are shown. DETAILED DESCRIPTION

[0037] Various exemplary embodiments, features and aspects of the present invention will be described in detail below. The word "exemplary" used here means "used as an example, embodiment or illustrative". Any embodiment described here as "exemplary" is not necessarily interpreted as being superior or better than other embodiments.

[0038] In addition, in order to better illustrate the present invention, numerous specific details are provided in the following specific embodiments. It should be understood by those skilled in the art that the present invention can be implemented without certain specific details. In other examples, methods, means, equipment and steps well known to those skilled in the art are not described in detail in order to highlight the subject matter of the present invention.

[0039] Unless otherwise stated, the units used in this specification are all international standard units, and the numerical values ​​and numerical ranges appearing in the present invention should be understood to include the inevitable systematic errors in industrial production.

[0040] In this specification, the word "may" means both performing a certain process and not performing a certain process.

[0041] In this specification, the references to "some specific / preferred embodiments", "other specific / preferred embodiments", "embodiments", etc., mean that the specific elements (e.g., features, structures, properties and / or characteristics) described in connection with the embodiments are included in at least one embodiment described herein, and may or may not exist in other embodiments. In addition, it should be understood that the elements may be combined in various embodiments in any suitable manner.

[0042] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints numerical values ​​A and B.

[0043] The present invention provides a method for measuring the softening temperature of rosin, which comprises the following steps:

[0044] 1) Setting a target temperature range R1-R2, using a nuclear magnetic resonance analyzer to measure the first nuclear magnetic signal of the rosin sample at different test temperatures in the target temperature range R1-R2, wherein R1 <R2;

[0045] 2) performing temperature correction on the first nuclear magnetic signal to obtain a second nuclear magnetic signal;

[0046] 3) establishing a first curve between the second nuclear magnetic signal and the different test temperatures;

[0047] 4) solving the derivative of the first curve to establish a second curve showing the rate of change of the second nuclear magnetic signal as the test temperature changes;

[0048] 5) Obtaining the softening temperature of the rosin sample according to the second curve.

[0049] The method for measuring the softening temperature of rosin of the present invention can conveniently and accurately measure the softening temperature of rosin, and in the measurement process, the influence of factors such as the operator of the detection process, environmental conditions, instruments and equipment, and detection parameters can be reduced.

[0050] In the present invention, the nuclear magnetic resonance analyzer is a low-field nuclear magnetic resonance analyzer coupled with a temperature control system, that is, the nuclear magnetic resonance analyzer has a temperature control system device, which can realize low-field nuclear magnetic resonance signal detection after the sample is subjected to temperature control.

[0051] In some specific embodiments, before detecting the first nuclear magnetic signal, the following steps are also included:

[0052] Using a standard oil sample and a free induction decay pulse sequence, the center frequency and pulse width of the nuclear magnetic resonance analyzer are calibrated;

[0053] Heating the rosin sample to obtain different test temperatures within a target temperature range R1 to R2 of the rosin sample;

[0054] After the rosin samples reach different test temperatures, they are kept warm and the first nuclear magnetic signal quantity detection is performed respectively.

[0055] The present invention does not specifically limit the standard oil sample, and it can be selected as needed. Specifically, the standard oil sample can be a standard oil sample that comes with the nuclear magnetic resonance analyzer, and generally can be a vegetable oil, such as soybean oil, peanut oil, olive oil, rapeseed oil, corn oil, sesame oil, etc. The standard oil sample is used to calibrate the center frequency and pulse width of the nuclear magnetic resonance analyzer using a free induction decay pulse sequence.

[0056] Further, the rosin sample is heated to obtain different test temperatures in the target temperature range R1 to R2 of the rosin sample. Specifically, the temperature change degree can be set, the temperature control system can be turned on, the sample can be heated and the temperature change of the sample can be measured at the same time.

[0057] In order to detect the first nuclear magnetic signal, the rosin sample can be kept warm after reaching different test temperatures, so as to facilitate the detection of the first nuclear magnetic signal. Further, in the present invention, the insulation time is 5 to 30 minutes, preferably 10 to 20 minutes, for example: 8 minutes, 10 minutes, 12 minutes, 15 minutes, 18 minutes, 20 minutes, 22 minutes, 25 minutes, 28 minutes, etc. When the insulation time is 5 to 30 minutes, the test can be completed.

[0058] Specifically, a target temperature range R1-R2 is set, and a nuclear magnetic resonance analyzer is used to measure the first nuclear magnetic signal quantity of the rosin sample at different test temperatures in the target temperature range R1-R2, wherein R1 <R2。

[0059] In some specific embodiments, the target temperature range R1-R2 is 25-150° C., preferably 50-120° C., and more preferably 70-100° C. By setting the target temperature range R1-R2 to 25-150° C., it is beneficial to test more rosin samples, especially for unknown rosin samples.

[0060] Under heating, rosin gradually changes from solid to molten state, then to softened state, and finally to liquid state. During the detection process, when the rosin is in solid state, the solid matrix signal decays very quickly, and the low-field nuclear magnetic resonance signal is not detected. However, when the rosin softens and becomes liquid, the matrix signal decays slowly, and the signal can be detected. Therefore, the softening temperature of rosin is the temperature at which the nuclear magnetic resonance signal first appears when the temperature increases from low (such as room temperature) to high.

[0061] In the present invention, the present invention determines different test temperatures in the target temperature range R1 to R2 by a temperature step. The temperature step can be determined by the requirements of the rosin sample detection accuracy, detection time, etc. Further, the temperature step between two adjacent test temperatures is 0.2 to 20°C, preferably 0.5 to 10°C, more preferably 1 to 5°C, and further preferably 1 to 3°C, for example: 2°C, 4°C, 6°C, 8°C, 10°C, 12°C, 14°C, 16°C, 18°C, etc. The temperature step of the present invention refers to the absolute value of the difference between two adjacent test temperatures.

[0062] The step sizes between different test temperatures within a target temperature range R1 to R2 may be the same or different; to optimize the test accuracy and increase the signal contrast at different temperature points, the test time may be further optimized.

[0063] The step lengths within a target temperature range (e.g., 30-90°C) can be the same (e.g., the test temperatures are 30°C, 50°C, 70°C, 90°C) or different (e.g., the test temperatures are 30°C, 50°C, 60°C, 70°C, 75°C, 80°C, 90°C). The temperature step length and test insulation accuracy between two adjacent test temperatures can be greater than or equal to the temperature control accuracy of the instrument.

[0064] The present invention does not specifically limit the sequence used for nuclear magnetic resonance detection, and any sequence that can obtain the total signal can be used, such as: multi-spin echo pulse sequence (Carr-Purcel-Meiboom-Gill, CPMG), free induction decay sequence (Free Induction Decay, FID), spin echo sequence (Spin Echo, SE), etc.

[0065] In some specific embodiments, a multi-spin echo pulse sequence is used to collect the transverse (spin-spin) relaxation time decay curve of the rosin sample to obtain the first nuclear magnetic signal. Specifically, the parameters for detecting the first nuclear magnetic signal include: a repeated scanning time interval of 500 to 5000 ms, preferably 1000 to 2000 ms, for example: 800 ms, 1200 ms, 1500 ms, 1800 ms, 2000 ms, 2500 ms, 3000 ms, 3500 ms, 4000 ms, 4500 ms, etc.; the number of 180° pulses is 3000 to 15000, preferably 3000 to 10000, for example: 4 The preferred embodiment of the present invention is as follows: the plurality of scanning paths are preferably 0,000, 5,000, 6,000, 7,000, 8,000, 9,000, 10,000, 12,000, 14,000, etc.; the 180° pulse echo time is 0.1-0.6ms, preferably 0.2-0.5ms, for example 0.3ms, 0.4ms, etc.; the number of repeated scans is 16-256 times, preferably 64-192 times, for example 32 times, 64 times, 96 times, 128 times, 160 times, 192 times, 224 times, etc.

[0066] For the NMR detection parameters, within the same target temperature range, the NMR detection parameters between each temperature point are the same. In order to optimize the test accuracy, improve the signal-to-noise ratio of the sampling signal, and increase the signal contrast at different temperature points, the NMR detection parameters between each temperature point are different within different target temperature ranges.

[0067] Further, the first nuclear magnetic signal is temperature corrected to eliminate the effect of the test temperature on the signal, thereby obtaining a second nuclear magnetic signal. In some specific embodiments, the temperature correction is performed according to the following formula (1), and the second nuclear magnetic signal can be obtained by temperature correction according to the above formula.

[0068] Iac =I bc ×(T j +273.15) / (T r +273.15) (1)

[0069] In the formula,

[0070] I ac is the second nuclear magnetic signal, au;

[0071] I bc is the first nuclear magnetic signal, au;

[0072] T j is the different test temperatures in the target temperature range R1 to R2, °C;

[0073] T r is the reference temperature, and T r ≥0℃, preferably, T r It can be 25 to 150°C.

[0074] In the present invention, T r It is the reference temperature and is generally not limited. r ≥0℃. Considering the accuracy of the test, T r It can be any temperature value in the target temperature range R1 to R2. Further, considering that it is easier to determine T r , then T r It is preferred to set the median temperature of the measurement temperature range in a certain step, for example: 60-80°C, etc. Of course, the T between different test steps r Can be the same or different.

[0075] Further, a first curve between the second nuclear magnetic signal and the different test temperatures is established. Specifically, the second nuclear magnetic signal of the rosin sample is plotted. ac The discrete point curve that changes with different test temperatures T is obtained to obtain the first curve.

[0076] Further, the first curve is subjected to derivative solution, so as to establish a second curve in which the rate of change of the second nuclear magnetic signal changes with the different test temperatures. And, in some specific embodiments, based on the second curve, the corresponding turning temperature when the rate of change of the second nuclear magnetic signal of the rosin sample reaches the maximum value is obtained, and the turning temperature is the softening temperature of the rosin sample. Specifically, the derivative solution can be a first-order derivative solution or a second-order derivative solution. When the derivative solution is a first-order derivative solution, the turning temperature of the second curve at the highest point is the softening temperature of the rosin sample, and when the derivative solution is a second-order derivative solution, the turning temperature of the second curve at 0 is the softening temperature of the rosin sample.

[0077] Taking the first derivative as an example, based on the first curve and the second curve in the present invention, as the test temperature increases from low to high, the temperature at which the second nuclear magnetic signal amount of the rosin sample determined from the first curve begins to increase significantly from small to large can be determined; from the second curve, the transition temperature corresponding to when the increase rate of the nuclear magnetic signal amplitude of the rosin sample first reaches the maximum value within the test temperature range can be determined, and this transition temperature is the softening temperature of the rosin sample. The transition temperature is the temperature point at which, as the test temperature increases from low to high, the second nuclear magnetic signal amount of the rosin sample begins to increase significantly and the change rate first reaches the maximum value; and the peak temperature corresponding to this conversion point is the softening temperature of the measured sample.

[0078] In the present invention, according to requirements such as the detection accuracy and detection time of the rosin sample, only one test can also be carried out, directly setting a smaller step size, that is, improving the accuracy. After multiple groups of tests, the softening temperature of the rosin sample can be directly obtained.

[0079] Furthermore, in the present invention, considering the detection time, the test can also be carried out in several rounds. When carrying out the first round of tests, a larger step size can be set, that is, reducing the accuracy, and the softening temperature range of the rosin sample to be detected can be narrowed according to the detection results. Then, based on the softening temperature range obtained after the first round of detection, the second round of tests and the third round of tests are carried out, and finally the softening temperature of the rosin sample is obtained.

[0080] In some specific implementation manners, when carrying out the first round of tests, a target temperature range R1 to R2 can be set, and then the softening temperature of the rosin sample is obtained according to the following steps. 1) Set the target temperature range R1 to R2, and use a nuclear magnetic resonance analyzer to measure the first nuclear magnetic signal amount of the rosin sample at different test temperatures within the target temperature range R1 to R2, where R1 < R2; 2) Perform temperature correction on the first nuclear magnetic signal amount to obtain the second nuclear magnetic signal amount; 3) Establish a first curve between the second nuclear magnetic signal amount and the different test temperatures; 4) Solve the derivative of the first curve to thereby establish a second curve showing the change rate of the second nuclear magnetic signal amount changing with the different test temperatures; 5) Obtain the softening temperature of the rosin sample according to the second curve.

[0081] After that, based on the softening temperature of the first round of tests, set the target temperature range R3 to R4, and repeat steps 1) to 5) to further obtain the softening temperature of the rosin sample measured in the second round; where R3 > R1, R4 < R2, and R3 < R4.

[0082] Furthermore, based on the softening temperature of the second round of tests, a target temperature range R5 to R6 can be set, and steps 1) to 5) are repeated to obtain a more accurate softening temperature of the rosin sample; where R5 > R3, R6 < R4, and R5 < R6.

[0083] Example

[0084] The embodiments of the present invention will be described in detail below in conjunction with the examples, but those skilled in the art will appreciate that the following examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. If no specific conditions are specified in the examples, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0085] Example 1

[0086] (1) The test was conducted using a nuclear magnetic resonance analyzer (Suzhou Newmai Analytical Instrument Co., Ltd., nuclear magnetic resonance analyzer VTMR20-010V-I, main magnetic field strength 0.5±0.03T, coil diameter: 10mm). Before the test, the center frequency and pulse width of the nuclear magnetic resonance analyzer were calibrated using a self-provided standard oil sample, and the calibration used a free induction decay pulse sequence.

[0087] (2) Take rosin sample A for testing, and set the measurement temperature program A-1 as follows: the target temperature range is 60-120°C, the temperature step between two adjacent test temperatures is 15°C, and the holding time after reaching the set temperature is 10 minutes.

[0088] (3) Weigh 0.445±0.003g of rosin sample A directly, put it into the NMR test sample bottle, and then place it in the NMR instrument for measurement. The NMR signal of rosin sample B is collected using a multi-spin echo pulse sequence, where the repeated scanning time interval TW is 1500ms, the number of 180° pulses NECH is 5000, the 180° pulse echo time TE is 0.3ms, the number of repeated scanning times NS is 64 times, and the NMR test is collected twice at each temperature, and the average value is taken as the NMR signal amount.

[0089] (4) Temperature correction is performed on the NMR signals collected by NMR testing at different set temperature points:

[0090] I ac =I bc ×(T j +273.15) / (T r +273.15)

[0091] In the formula,

[0092] I ac is the second nuclear magnetic signal, au;

[0093] I bc is the first nuclear magnetic signal, au;

[0094] T jis the different test temperatures in the target temperature range, °C;

[0095] T r is the reference temperature, and T r is 70℃.

[0096] (5) Draw a curve curve 1 showing the change of the NMR signal of sample A after correction with the test temperature, solve the first-order derivative of curve curve 1, and obtain the rate curve curve curve 2 showing the change of the NMR signal with the test temperature. Determine the temperature T corresponding to the turning point when the rate of increase of the NMR signal corresponding to the temperature program A-1 first reaches the maximum value from curve 1 and curve 2. peak1 is 90℃, such as Figure 1 as shown in step 1 of .

[0097] (6) Continue to take rosin sample A for testing, and set the measurement temperature program A-2 as follows: the target temperature range is 75-105°C, the temperature step length between two adjacent test temperatures is 5°C, and the holding time after reaching the set temperature is 10 minutes. Repeat steps (3), (4) and (5) to determine the temperature T corresponding to the turning point when the nuclear magnetic signal increase rate corresponding to temperature program A-2 first reaches the maximum value. peak2 is 85℃, such as Figure 1 as shown in step 2 of .

[0098] (7) Take rosin sample A for further testing, and set the measurement temperature program A-3 as follows: the target temperature range is 80-90°C, the temperature step length between two adjacent test temperatures is 1°C, and the holding time is 10 minutes after reaching the set temperature. Repeat steps (3), (4) and (5) to determine the temperature T corresponding to the turning point when the nuclear magnetic resonance signal increase rate corresponding to temperature program A-3 first reaches the maximum value. peak3 is 86℃, which is the final target softening temperature. Figure 1 as shown in step 3 of .

[0099] Example 2

[0100] (1) The test was conducted using a nuclear magnetic resonance analyzer (Suzhou Newmai Analytical Instrument Co., Ltd., nuclear magnetic resonance analyzer VTMR20-010V-I, main magnetic field strength 0.5±0.03T, coil diameter: 10mm). Before the test, the center frequency and pulse width of the nuclear magnetic resonance analyzer were calibrated using a self-provided standard oil sample, and the calibration used a free induction decay pulse sequence.

[0101] (2) Take rosin sample B for testing, and set the measurement temperature program B-1 as follows: the target temperature range is 60-120°C, the step length is 15°C, and the holding time is 10 minutes after reaching the set temperature.

[0102] (3) Weigh 0.447±0.001g of rosin sample B directly, put it into the NMR test sample bottle, and then put it into the NMR instrument for measurement. The NMR signal of rosin sample B was collected using a multi-spin echo pulse sequence, where the repeated scanning time interval TW was 1500ms, the number of 180° pulses NECH was 5000, the 180° pulse echo time TE was 0.3ms, the number of repeated scanning times NS was 64 times, and the NMR test was collected twice at each temperature, and the average value was taken as the NMR signal amount.

[0103] (4) Temperature correction is performed on the NMR signals collected by NMR testing at different set temperature points:

[0104] I ac =I bc ×(T j +273.15) / (T r +273.15)

[0105] In the formula,

[0106] I ac is the second nuclear magnetic signal, au;

[0107] I bc is the first nuclear magnetic signal, au;

[0108] T j is the different test temperatures in the target temperature range, °C;

[0109] T r is the reference temperature, and T r is 70℃.

[0110] (5) Draw the curve curve1 of the change of the nuclear magnetic signal of sample B after correction with the test temperature, solve the first-order derivative of curve curve1, and obtain the rate curve curve curve2 of the change of the nuclear magnetic signal with the test temperature. Determine the temperature T corresponding to the turning point when the rate of increase of the nuclear magnetic signal corresponding to temperature program B-1 first reaches the maximum value from curve1 and curve2. peak1 is 90℃, such as Figure 2 as shown in step 1 of .

[0111] (6) Continue to take rosin sample B for testing, set the measurement temperature program B-2: the target temperature range is 75-105℃, the step length is 5℃, and the holding time is 10min after reaching the set temperature. Repeat steps (3), (4) and (5) to determine the temperature T corresponding to the turning point when the rate of increase of the nuclear magnetic resonance signal corresponding to the temperature program B-2 first reaches the maximum value. peak2 is 90℃, such as Figure 2 as shown in step 2 of .

[0112] (7) Take rosin sample B for further testing and set the measurement temperature program B-3: the target temperature range is 85-95°C, the step length is 1°C, and the holding time is 10 min after reaching the set temperature. Repeat steps (3), (4) and (5) to determine the temperature T corresponding to the turning point when the rate of increase of the nuclear magnetic resonance signal corresponding to the temperature program B-3 first reaches the maximum value. peak3 is 89°C, which is the final target softening temperature. Figure 2 as shown in step 3 of .

[0113] Example 3

[0114] (1) The test was conducted using a nuclear magnetic resonance analyzer (Suzhou Newmai Analytical Instrument Co., Ltd., nuclear magnetic resonance analyzer VTMR20-010V-I, main magnetic field strength 0.5±0.03T, coil diameter: 10mm). Before the test, the center frequency and pulse width of the nuclear magnetic resonance analyzer were calibrated using a self-provided standard oil sample, and the calibration used a free induction decay pulse sequence.

[0115] (2) Take rosin sample C for testing and set the measurement temperature program: the target temperature range is 90-95°C, the step length is 1°C, and the insulation time is 10 minutes after reaching the set temperature.

[0116] (3) Weigh 0.4475 g of rosin sample C directly, put it into the NMR test sample bottle, and then put it into the NMR instrument for measurement. The NMR signal of rosin sample C was collected using a multi-spin echo pulse sequence, where the repeated scanning time interval TW was 1500 ms, the number of 180° pulses NECH was 5000, the 180° pulse echo time TE was 0.3 ms, the number of repeated scanning times NS was 64 times, and the NMR test was collected twice at each temperature, and the average value was taken as the NMR signal amount.

[0117] (4) Temperature correction is performed on the NMR signals collected by NMR testing at different set temperature points:

[0118] I ac =I bc ×(T j +273.15) / (T r +273.15)

[0119] In the formula,

[0120] I ac is the second nuclear magnetic signal, au;

[0121] I bc is the first nuclear magnetic signal, au;

[0122] T j is the different test temperatures in the target temperature range, °C;

[0123] T r is the reference temperature, and T r is 70℃.

[0124] (5) Draw the curve curve1 of the change of the nuclear magnetic signal of sample C after correction with the test temperature, solve the first-order derivative of curve curve1, and obtain the rate curve curve curve2 of the change of the nuclear magnetic signal with the test temperature. Determine the temperature T corresponding to the turning point when the corresponding nuclear magnetic signal increase rate reaches the maximum value from curve1 and curve2. peak is 93°C, which is the final target softening temperature. Figure 3 shown.

[0125] Test verification

[0126] In addition, the rosin sample A in Example 1, the rosin sample B in Example 2, and the rosin sample C in Example 3 were tested for softening temperature using the "7.5 softening point determination" in GB / T 8146-2022 "Rosin Test Method", i.e., the standard ring and ball method, and the measured results were 84.0°C, 86.9°C, and 92.2°C, respectively. The relative deviations (percentages of absolute deviations and standard method measured values) from the softening temperatures of samples A, B, and C measured using the method of the present invention, which were 86°C, 89°C, and 93°C, respectively, were only 2.38%, 2.42%, and 0.87%, respectively. It can be seen that the method of the present application can be used to measure the softening temperature of rosin.

[0127] In summary, the method for measuring the softening temperature of rosin of the present invention can be measured by directly placing a small amount of the sample to be tested into the nuclear magnetic resonance instrument, and the detection accuracy is good.

[0128] It should be noted that, although the technical solution of the present invention is introduced with specific examples, those skilled in the art will appreciate that the present invention should not be limited thereto.

[0129] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A method for measuring the softening temperature of rosin, characterized in that: It includes the following steps: 1) Set the target temperature range R1 to R2, and use a nuclear magnetic resonance analyzer to measure the first nuclear magnetic signal quantity of the rosin sample at different test temperatures within the target temperature range R1 to R2, where R1 < R2; 2) Perform temperature correction on the first nuclear magnetic signal quantity to obtain the second nuclear magnetic signal quantity; 3) Establish a first curve between the second nuclear magnetic signal quantity and the different test temperatures; 4) Solve the derivative of the first curve to thereby establish a second curve showing the change rate of the second nuclear magnetic signal quantity varying with the different test temperatures; 5) Obtain the softening temperature of the rosin sample based on the first curve and the second curve.

2. The method according to claim 1, characterized in that: The nuclear magnetic resonance analyzer is a low-field nuclear magnetic resonance analyzer with a coupled temperature control system.

3. The method according to claim 1 or 2, characterized in that: Before detecting the first nuclear magnetic signal quantity, the following steps are also included: Use a standard oil sample and a free induction decay pulse sequence to correct the center frequency and pulse width of the nuclear magnetic resonance analyzer; Heat the rosin sample to obtain different test temperatures within the target temperature range R1 to R2 of the rosin sample; After the rosin sample reaches different test temperatures, keep it warm and perform the detection of the first nuclear magnetic signal quantity respectively.

4. The method according to claim 3, characterized in that The target temperature range R1 to R2 is 25 to 150 °C; the temperature step between adjacent two test temperatures is 0.2 to 20 °C; the time for keeping warm is 5 to 30 min.

5. The method according to any one of claims 1 to 4, characterized in that: The parameters for detecting the first nuclear magnetic signal quantity include: the repetition scan time interval is 500 to 5000 ms; the number of 180° pulses is 3000 to 15000; the echo time of the 180° pulse is 0.1 to 0.6 ms, and the number of repeated scans is 16 to 256 times.

6. The method according to any one of claims 1 to 5, characterized in that: The temperature correction is carried out according to the following formula (1): I ac =I bc ×(T j +273.15) / (T r +273.15) (1) In the formula, I ac is the second nuclear magnetic signal, au; I bc is the first nuclear magnetic signal, au; T j is the different test temperatures in the target temperature range R1 to R2, °C; T r is the reference temperature, and T r ≥0℃.

7. The method according to claim 6, characterized in that T r 25~150℃.

8. The method according to any one of claims 1 to 7, characterized in that: Based on the second curve, obtain the transition temperature corresponding to when the change rate of the second nuclear magnetic signal quantity of the rosin sample reaches the maximum value, and the transition temperature is the softening temperature of the rosin sample.

9. The method according to any one of claims 1 to 8, characterized in that: According to the set target temperature range R3 to R4, repeat steps 1) to 5) to obtain the softening temperature of the rosin sample; where R3 > R1, R4 < R2, and R3 < R4.

10. The method according to claim 9, characterized in that According to the set target temperature range R5 to R6, repeat steps 1) to 5) to obtain the softening temperature of the rosin sample; where R5 > R3, R6 < R4, and R5 < R6.

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