A method for quantitatively analyzing the weight fraction of natural rubber and / or polyisoprene in tire rubber

Abstract

The present invention relates to the technical field of tire formulation design, and more particularly to a method, application, and computer program product for quantifying the weight fraction of natural rubber and / or polyisoprene rubber using thermogravimetric analysis. A method for quantitatively analyzing the weight fraction of natural rubber and / or polyisoprene rubber in tire rubber compounds uses a single TGA test to simultaneously determine the weight ratios of volatile small molecules, pyrolytic macromolecules, combustibles such as carbon black, and residual ash. The method also accurately calculates the weight ratio of natural rubber and / or polyisoprene rubber (NR) to other synthetic rubbers (continued to be designated SR) in the formulation. The weight fraction of NR is then calculated based on 100 parts of the total weight of rubber in the formulation. Verification based on actual formulations shows that the weight fraction of NR calculated using this method deviates within 3 parts of the actual formulation, providing a more accurate method for analyzing the rubber ratio of competing tire formulations.

Description

Technical Field

[0001] The present invention relates to the technical field of tire formulation design, and in particular to a method, application and computer program product for quantifying the weight fraction of natural rubber and / or polyisoprene rubber by thermogravimetric analysis. Background Art

[0002] With the continuous development of the tire industry, tire technology and high-performance tires are constantly improving. The world's top tire manufacturers are competing to develop high-performance tires, including European label 2A (rolling resistance A, wet skid A) and even 3A (rolling resistance A, wet skid A, noise A) tires. In order to improve the company's tire design technology and brand influence, other companies will conduct a comprehensive anatomical analysis of these 2A or 3A tires.

[0003] For tire formula analysis, thermogravimetric analysis (hereinafter referred to as TGA) is an indispensable analytical method. A single TGA analysis can simultaneously determine the weight ratios of volatile small molecules, crackable macromolecules, combustibles such as carbon black, and residual ash in the formula. It can also roughly estimate the weight fraction of natural rubber or polyisoprene rubber (hereinafter referred to as NR) in the formula. To further obtain a relatively accurate weight fraction of NR, additional infrared testing, LC-MAS testing, GS-MAS testing, etc. are required, and the results obtained from these tests usually have large errors.

[0004] If, in a TGA test, in addition to obtaining the weight ratios of volatile small molecules, decomposable macromolecules, combustibles such as carbon black, and residual ash, the weight ratio of NR and SR in the formula can be more accurately quantitatively calculated, and then the weight fraction of NR can be calculated, then the test cycle will be shortened and a basis for further and more accurate analysis of the rubber ratio in the formula will be provided. This will provide more effective guidance for the research and development design of the formula and the improvement of the company's tire performance. Summary of the Invention

[0005] In order to solve the above technical problems, the purpose of the present invention is to provide a method for quantifying the weight proportions of natural rubber and / or polyisoprene rubber by thermogravimetric analysis. This method uses a single TGA test to simultaneously obtain the weight proportions of volatile small molecules, decomposable macromolecules, combustibles such as carbon black, and residual ash. It can also more accurately calculate the weight proportions of NR and other synthetic rubbers (continued to use the SR designation) in the formula, and then calculate the weight proportions of NR according to 100 parts of the total weight of rubber in the formula.

[0006] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0007] A method for quantitatively analyzing the weight fraction of natural rubber and / or polyisoprene in tire rubber material, the method comprising the following steps:

[0008] 1) Weigh 5-10 mg of sample into a ceramic crucible for thermogravimetric analysis and record the weight.

[0009] 2) Perform a weight loss test on the sample using the thermogravimetric analysis (TGA) test program to obtain a TGA curve;

[0010] TGA's testing procedures include the following:

[0011] Program segment 1: temperature range 30℃-300℃, heating rate 20℃ / min, N2 atmosphere, gas flow rate 50ml / min;

[0012] Program segment 2: 300°C for 5 min, N2 atmosphere, gas flow rate 50 ml / min;

[0013] Program segment 3: temperature range is 300℃-650℃, heating rate is 20℃ / min, N2 atmosphere, gas flow rate is 50ml / min;

[0014] Program segment 4: 300°C for 5 min, N2 atmosphere, gas flow rate 50 ml / min;

[0015] Program segment 5: temperature range is 300℃-650℃, heating rate is 20℃ / min, O2 atmosphere, gas flow rate is 50ml / min;

[0016] 3) performing first-order derivative and second-order derivative of the TGA curve to obtain a TGA weight loss curve, a first-order derivative curve, and a second-order derivative curve;

[0017] 4) Find the characteristic temperatures A, B, C, and D based on the TGA curve, first-order derivative curve, and second-order derivative curve;

[0018] A is the starting temperature point of test program segment 3 on the TGA curve,

[0019] B is the peak temperature point between 380-430℃ corresponding to the peak position E on the second-order derivative curve,

[0020] C is the temperature point corresponding to temperature B+20℃,

[0021] D is the end temperature point of TGA curve test program segment 4;

[0022] If there is no peak between 380-430°C on the second-order derivative curve, it means that the natural rubber and / or polyisoprene in the tire rubber compound is zero;

[0023] 5) Calculate the ratio of natural rubber and / or polyisoprene to other synthetic rubber according to the calculation formula. Natural rubber and / or polyisoprene is represented by NR, and other synthetic rubber is represented by SR;

[0024] The formula for calculating the ratio of NR to SR is: NR:SR=△G AC :(△G AD -△G AC ); △G in the formula represents the weight loss between two temperature points calculated by the program on the computer, where △G AC and △G AD are the weight loss percentages between temperature points A and C, and A and D, respectively, and the total weight of the sample is recorded as 100%;

[0025] 6) Calculate the weight percentage of NR in tire rubber according to the calculation formula

[0026] The formula for calculating the weight percentage of NR in tire rubber is: Weight percentage of NR = △G AC :(△G AD -△G AC ) / [ 1+△G AC :(△G AD -△G AC )].

[0027] Preferably, the other synthetic rubber is at least one of styrene-butadiene rubber (SBR), butadiene rubber (BR), butyl rubber (IR) and halogenated butyl rubber.

[0028] Preferably, the tread rubber contains no resin or contains a small amount of resin, and the weight of the resin used is less than 15 phr based on 100 phr of rubber in the formula. More preferably, the weight of the resin used is less than 10 phr.

[0029] Furthermore, the present invention also discloses the application of the method in calculating the weight fraction of natural rubber and / or polyisoprene in tire formulation design.

[0030] Furthermore, the present invention also discloses a TGA test method for tire rubber materials, wherein the TGA test procedure of the method includes the following procedures:

[0031] Program segment 1: temperature range 30℃-300℃, heating rate 20℃ / min, N2 atmosphere, gas flow rate 50ml / min;

[0032] Program segment 2: 300°C for 5 min, N2 atmosphere, gas flow rate 50 ml / min;

[0033] Program segment 3: temperature range is 300℃-650℃, heating rate is 20℃ / min, N2 atmosphere, gas flow rate is 50ml / min;

[0034] Program segment 4: 300°C for 5 min, N2 atmosphere, gas flow rate 50 ml / min;

[0035] Program segment 5: temperature range is 300℃-650℃, heating rate is 20℃ / min, O2 atmosphere, gas flow rate is 50ml / min.

[0036] Furthermore, the present invention also discloses a computer device comprising a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement steps 3) to 5) in a method for quantitatively analyzing the weight fraction of natural rubber and / or polyisoprene in tire rubber or a test program for a thermogravimetric analysis (TGA) test method for tire rubber.

[0037] Furthermore, the present invention also discloses a computer-readable storage medium having a computer program or instruction stored thereon. When the computer program or instruction is executed by a processor, it implements steps 3) to 5) in a method for quantitatively analyzing the weight fraction of natural rubber and / or polyisoprene in tire rubber or a test program for a thermogravimetric analysis (TGA) test method for tire rubber.

[0038] The invention is used to implement the test procedures of steps 3) to 5) in a method for quantitatively analyzing the weight fraction of natural rubber and / or polyisoprene in tire rubber materials or a thermogravimetric analysis (TGA) test method for tire rubber materials.

[0039] A computer program product includes a computer program or instructions that, when executed by a processor, implements steps 3) to 5) of a method for quantitatively analyzing the weight fraction of natural rubber and / or polyisoprene in tire rubber or a test procedure for a thermogravimetric analysis (TGA) test method for tire rubber.

[0040] The testing principle of the present invention is as follows: The first-order derivative of the TGA curve shows that the primary TGA weight loss of NR is concentrated between 340°C and 440°C. The fastest weight loss rate in this TGA program occurs at 390±5°C, after which the weight loss rate gradually decreases, with the weight loss rate being essentially symmetrical on the left and right sides of 390±5°C. The primary TGA weight loss of SR is concentrated between 420°C and 490°C, with the fastest weight loss rate occurring at 460±5°C. The first-order derivative of the curve shows that the weight loss rate is essentially symmetrical on the left and right sides of 460±5°C. Based on actual verification, the calculated results are most consistent with the actual formulation when NR continues to lose weight by 20°C after reaching its peak rate. Furthermore, because the primary TGA weight loss of α-methylstyrene resins, C5 resins, and other resins overlaps with that of rubber, the present invention is suitable for tire formulations with low resin content. The resin content can be determined through physical property analysis, DMA analysis, or other chemical analysis methods.

[0041] Since the present invention adopts the above-mentioned technical solution, the method uses a single TGA test to simultaneously obtain the weight ratios of volatile small molecules, decomposable macromolecules, combustibles such as carbon black, and residual ash. It can also more accurately calculate the weight ratios of NR and other synthetic rubbers (continued to use the SR designation) in the formula, and then calculate the weight ratios of NR based on 100 parts of the total weight of rubber in the formula. Verified by the actual formula, the weight ratios of NR calculated by this method are within 3 parts of the actual formula, which provides a more accurate method for analyzing the rubber ratios of competing tires. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 The TGA curve of the sample to be tested using the TGA test program for weight loss test. DETAILED DESCRIPTION

[0043] The following will be combined with the embodiments of the present invention to provide a complete and comprehensive description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Given the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0044] The present invention selected 10 vulcanized rubbers, all of which contained 100 parts by weight of rubber. Examples 1 to 7 all added less than 15 parts of resin. Comparative Examples 1 to 3 all used more than 15 parts of resin, which did not meet the requirements.

[0045] △G is the result obtained directly from the weight loss in the TGA graph according to the computer program. All TGA test conditions are the same and are measured according to the following procedure:

[0046] Program segment 1: temperature range 30℃-300℃, heating rate 20℃ / min, N2 atmosphere, gas flow rate 50ml / min;

[0047] Program segment 2: 300°C for 5 min, N2 atmosphere, gas flow rate 50 ml / min;

[0048] Program segment 3: temperature range is 300℃-650℃, heating rate is 20℃ / min, N2 atmosphere, gas flow rate is 50ml / min;

[0049] Program segment 4: 300°C for 5 min, N2 atmosphere, gas flow rate 50 ml / min;

[0050] Program segment 5: temperature range is 300℃-650℃, heating rate is 20℃ / min, O2 atmosphere, gas flow rate is 50ml / min;

[0051] In Table 1, ΔG AC and △G AD The percentage weight loss between temperature points A and C, and A and D, respectively, obtained using a computer program, is calculated. The total sample weight is taken as 100%. A, B, C, and D are characteristic temperature points in the TGA curve, first-order derivative curve, and second-order derivative curve. A is the starting temperature of test segment 3 on the TGA curve, B is the peak temperature between 380°C and 430°C corresponding to peak position E on the second-order derivative curve, C is the temperature corresponding to temperature B + 20°C, and D is the end temperature of test segment 4 on the TGA curve.

[0052] In Table 1, theoretical NR:SR=parts by weight of NR / parts by weight of SR;

[0053] In Table 1, the weight percentage of NR is expressed as ΔG. AC :(△G AD -△G AC ) calculated by weight of NR, the calculation formula is: NR weight = △ G AC :(△G AD -△G AC ) / [ 1+△G AC :(△G AD -△G AC )]

[0054] △G NR It is the difference between the weight fraction of NR calculated by TGA and the weight fraction of NR in the actual formula. A positive value indicates that the calculated value is higher than the amount in the actual formula. A negative value indicates that the calculated value is lower than the amount in the actual formula. The higher the absolute value, the greater the deviation from the actual value.

[0055] Table 1

[0056] Vulcanized rubber Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Comparative Example 1 Comparative Example 2 Comparative Example 3 NR parts by weight 10 20 40 60 80 90 80 20 50 90 SR weight parts 90 80 60 40 20 10 20 80 50 10 Resin weight 0 5 5 10 14 8 0 30 40 30 Other components in parts by weight 120 120 120 120 120 120 120 120 120 120 Total weight parts 220 225 225 230 234 228 220 250 260 250 Theoretical NR:SR 0.11 0.25 0.67 1.50 4.00 9.00 4.00 0.25 1.00 9.00 △GAC:(△GAD-△GAC) 0.10 0.27 0.68 1.65 4.88 9.78 3.80 0.55 1.55 11.10 IR weight parts 9.09 21.26 40.48 62.26 82.99 90.72 79.17 35.90 60.78 91.74 <![CDATA[△G NR ]]> -0.91 1.26 0.48 2.26 2.99 0.72 -0.83 15.90 10.78 1.74

[0057] △G calculated from the table NR The results show that when the weight of the resin is less than 15 parts, △G NR They are all lower than 3, indicating that the difference between the calculated results and the results in the actual formula is less than 3. However, when the resin amount is higher than 15 parts, the deviation is larger, especially when the weight of NR is much lower than that of SR, the deviation is even greater.

[0058] This patent mainly uses TGA to quantitatively calculate the weight ratio of NR to other rubbers in the formula, and then calculates the weight ratio of NR in the vulcanized rubber formula based on the total weight of rubber in the formula as 100 parts. The accuracy is characterized by comparing the difference between the calculated weight of NR and the weight of NR in the actual formula. This experiment believes that △G NRIf the value is less than 3, the result is accurate.

[0059] The above is a description of the embodiments of the present invention. The above description of the disclosed embodiments will enable professionals in the field to implement or use the present invention. Various modifications to these embodiments will be apparent to professionals in the field. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but should conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for quantitatively analyzing the weight fraction of natural rubber and / or polyisoprene in tire rubber, characterized in that: The method comprises the following steps: 1) Weigh 5-10 mg of sample into a ceramic crucible for thermogravimetric analysis and record the weight. 2) Perform a weight loss test on the sample using the thermogravimetric analysis (TGA) test program to obtain a TGA curve; TGA's testing procedures include the following: Program segment 1: temperature range 30℃-300℃, heating rate 20℃ / min, N2 atmosphere, gas flow rate 50ml / min; Program segment 2: 300°C for 5 min, N2 atmosphere, gas flow rate 50 ml / min; Program segment 3: temperature range is 300℃-650℃, heating rate is 20℃ / min, N2 atmosphere, gas flow rate is 50ml / min; Program segment 4: 300°C for 5 min, N2 atmosphere, gas flow rate 50 ml / min; Program segment 5: temperature range is 300℃-650℃, heating rate is 20℃ / min, O2 atmosphere, gas flow rate is 50ml / min; 3) performing first-order derivative and second-order derivative of the TGA curve to obtain a TGA weight loss curve, a first-order derivative curve, and a second-order derivative curve; 4) Find the characteristic temperatures A, B, C, and D based on the TGA curve, first-order derivative curve, and second-order derivative curve; A is the starting temperature point of test program segment 3 on the TGA curve, B is the peak temperature point between 380-430℃ corresponding to the peak position E on the second-order derivative curve, C is the temperature point corresponding to temperature B+20℃, D is the end temperature point of TGA curve test program segment 4; If there is no peak between 380-430°C on the second-order derivative curve, it means that the natural rubber and / or polyisoprene in the tire rubber compound is zero; 5) Calculate the ratio of natural rubber and / or polyisoprene to other synthetic rubber according to the calculation formula. Natural rubber and / or polyisoprene is represented by NR, and other synthetic rubber is represented by SR; The formula for calculating the ratio of NR to SR is: NR:SR=△G AC :(△G AD -△G AC ); △G in the formula represents the weight loss between two temperature points calculated by the program on the computer, where △G AC and △G AD are the weight loss percentages between temperature points A and C, and A and D, respectively, and the total weight of the sample is recorded as 100%; 6) Calculate the weight percentage of NR in tire rubber according to the calculation formula The formula for calculating the weight percentage of NR in tire rubber is: Weight percentage of NR = △G AC :(△G AD -△G AC ) / [ 1+△G AC :(△G AD -△G AC )].

2. The method for quantitatively analyzing the weight fraction of natural rubber and / or polyisoprene in tire rubber according to claim 1, characterized in that: The other synthetic rubber is at least one of styrene-butadiene rubber (SBR), butadiene rubber (BR), butyl rubber (IR) and halogenated butyl rubber.

3. The method for quantitatively analyzing the weight fraction of natural rubber and / or polyisoprene in tire rubber according to claim 1, characterized in that: The tread rubber does not include resin or includes a small amount of resin. Based on the weight of the rubber in the formula being 100 phr, the weight of the resin used must be less than 15 phr.

4. The method for quantitatively analyzing the weight fraction of natural rubber and / or polyisoprene in tire rubber according to claim 3, characterized in that: The weight percentage of the resin used should be less than 10 phr.

5. Use of the method according to any one of claims 1 to 4 in calculating the weight fraction of natural rubber and / or polyisoprene in tire formulation design.

6. A computer device comprising a memory, a processor, and a computer program stored in the memory, wherein: The processor executes the computer program to implement step 3) to step 5) of the method according to any one of claims 1 to 4.

7. A computer-readable storage medium having a computer program or instruction stored thereon, characterized in that: When the computer program or instruction is executed by a processor, steps 3) to 5) of the method according to any one of claims 1 to 4 are implemented.

8. A computer program product comprising a computer program or instructions, characterized in that When the computer program or instruction is executed by a processor, steps 3) to 5) of the method according to any one of claims 1 to 4 are implemented.

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