Method for determining mass content of white carbon black in tire rubber

Abstract

The invention provides a method for determining the mass content of white carbon black in tire rubber. The determination method comprises the following steps: determining silicon dioxide mass content test values of n tire rubber test articles through a silicon dioxide test method, calculating the ratio of the mass content of white carbon black to the silicon dioxide mass content test values in the n tire rubber test articles, obtaining the average value of n ratios, and recording the average value as A; wherein n is greater than or equal to 5; establishing a conversion formula between the mass content of the white carbon black and the mass content of the silicon dioxide in the tire rubber sample, wherein the conversion formula is that the mass content of the white carbon black is equal to A * the mass content of the silicon dioxide, and A is 1.07-1.13; obtaining a silicon dioxide mass content test value of the tire rubber to-be-tested product through the silicon dioxide test method; and substituting the mass content test value of the silicon dioxide into a conversion formula for calculation to obtain the mass content of the white carbon black in the to-be-tested tire rubber product. According to the determination method, the quantitative accuracy of the mass content of the white carbon black is improved.

Description

Technical Field

[0001] The invention relates to the technical field of rubber testing, and in particular to a method for determining the mass content of white carbon black in tire rubber. Background Art

[0002] With the development of green tires, the use of silica in tire rubber is becoming increasingly widespread, particularly in tread compounds. Compared to traditional carbon black, the addition of silica effectively reduces tire rolling resistance, significantly reduces tire heat buildup, and improves wet skid resistance. Therefore, silica has become an indispensable additive in high-performance tires. This, in turn, places higher demands on the quantitative accuracy of silica in tire rubber.

[0003] A Chinese patent application, published as CN113447393A, provides a quantitative method for determining the silica content in silicone rubber. This method uses a pyrolysis method to crack a polymer, then adds hydrofluoric acid. This reaction between the hydrofluoric acid and silica produces silicon fluoride gas, which reduces the sample's mass. This reduction represents the silica content in the silicone rubber. Since silica contains not only silica but also a certain amount of bound water, represented by SiO₂·nH₂O, where nH₂O exists as surface hydroxyl groups, the silica content determined by this method is not equal to (but rather less than) the silica content actually added to the formula.

[0004] The current method for measuring silica content in tire rubber shows a significant discrepancy between the silica content and the actual amount of silica added. Therefore, there is an urgent need to develop a method that can accurately measure silica content in tire rubber. Summary of the Invention

[0005] The main purpose of the present invention is to provide a method for determining the mass content of silica in tire rubber, so as to solve the problem of poor accuracy of the methods for determining the mass content of silica in tire rubber in the prior art.

[0006] To achieve the above-mentioned object, according to one aspect of the present invention, a method for determining the mass content of silica in tire rubber is provided, the method comprising: step S1, weighing the mass of the tire rubber sample and recording it as the initial mass, subjecting the tire rubber sample to carbonization, a first calcination and cooling in sequence to obtain ash and weighing the mass of the ash and recording it as the intermediate mass; step S2, mixing the first water and the ash to obtain the wetted ash; mixing the wetted ash with the first hydrofluoric acid and sequentially performing the first evaporation and cooling to obtain the first product; step S3, mixing the first product with the second water to obtain the second product; mixing the second product with the second hydrofluoric acid and sequentially performing the second evaporation, the second calcination and cooling to obtain the final product and weighing the mass of the final product and recording it as the final mass; step S4, taking the difference between the intermediate mass and the final mass as the mass of silica in the tire rubber sample, and calculating the mass content of silica in the tire rubber sample; step S5, when the tire rubber sample is When there are n different tire rubber test samples with known silica mass content, the tire rubber test samples are sequentially subjected to steps S1 to S4 to obtain the silica mass content test value corresponding to each tire rubber sample; the ratio of the silica mass content to the silica mass content test value in the n tire rubber test samples is calculated, and the average value of the n ratios is obtained, recorded as A; wherein n ≥ 5; step S6, establishing a conversion formula between the silica mass content and the silica mass content in the tire rubber sample: silica mass content = A × silica mass content, where A is 1.07 to 1.13; step S7, when the tire rubber sample is a tire rubber test sample with unknown silica mass content, the tire rubber test sample is sequentially subjected to steps S1 to S4 to obtain the silica mass content test value corresponding to the tire rubber test sample; the silica mass content test value is substituted into the conversion formula for calculation to obtain the silica mass content in the tire rubber test sample.

[0007] Furthermore, in the above step S1, the mass content of white carbon black in the tire rubber sample is 5-45%, and / or the specific surface area of white carbon black in the tire rubber sample is 60-280 m 2 / g.

[0008] Furthermore, in the above step S1, the carbonization temperature is 200-300° C., and the carbonization time is 15-30 minutes.

[0009] Furthermore, in the above step S1, the temperature of the first calcination is 950-1000° C., and the time of the first calcination is 1-1.2 hours.

[0010] Furthermore, in the above step S2, the volume of the first water is 2 to 5 mL; and / or the volume of the first hydrofluoric acid is 5 to 10 mL.

[0011] Furthermore, in the above step S2, the temperature of the first evaporation is 80-100°C, and the time of the first evaporation is 10-20 minutes.

[0012] Furthermore, in the above step S3, the volume of the second water is 1 to 3 mL; and / or the volume of the second hydrofluoric acid is 2 to 5 mL.

[0013] Furthermore, in the above step S3, the temperature of the second evaporation is 80-100° C., and the time of the second evaporation is 10-20 minutes.

[0014] Furthermore, in the above step S3, the temperature of the second calcination is 950-1000° C., and the time of the second calcination is 1-1.2 hours.

[0015] Furthermore, A is 1.08 to 1.12.

[0016] Applying the technical solution of the present invention, to address the issue of silica content not actually being equal to silica content, the present applicant first subjected multiple tire rubber samples with varying silica content to steps S1 through S4, determining the coefficient relationship between silica content and silica content and establishing a conversion formula. Therefore, simply by measuring the silica content in the tire rubber sample according to steps S1 through S4 and calculating using the conversion formula described herein, the silica content in the tire rubber sample can be determined. Furthermore, the present determination method not only significantly improves the accuracy of quantitative determination of silica content in tire rubber, but also offers broad applicability, applicable to tire rubber samples with varying silica content and silica grades. Steps S1 through S4 enable accurate determination of silica content. Specifically, in step S1, the tire rubber sample is carbonized until the ash becomes white, removing most of the organic matter. The first calcination thoroughly decomposes any remaining organic matter in the sample, yielding the ash content without affecting the ash composition. By adding hydrofluoric acid in step S2 and step S3, react with the silicon dioxide in the ash to generate silicon fluoride gas, can remove moisture by above-mentioned first evaporation and second evaporation, simultaneously make the silicon fluoride generated evaporate, thereby make the sample quality after drying more stable.In addition, adding water can prevent hydrofluoric acid from reacting too violently with ash.Can further remove a small amount of residual organic matter or reaction product by the second calcination, thereby improve the quality determination accuracy of final silicon dioxide.Can fully react with ash by adding hydrofluoric acid in batches, thereby improve the quality determination accuracy of final silicon dioxide.By step S4, the difference between intermediate mass and final mass / initial mass of tire rubber sample can obtain the mass content of silicon dioxide in tire rubber sample. DETAILED DESCRIPTION

[0017] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the embodiments.

[0018] As analyzed in the background technology of this application, the method for determining the mass content of silica in tire rubber in the prior art has the problem of poor accuracy. In order to solve the above problem, this application provides a method for determining the mass content of silica in tire rubber.

[0019] In a typical embodiment of the present application, a method for determining the mass content of silica in tire rubber is provided, the determination method comprising: step S1, weighing the mass of the tire rubber sample and recording it as the initial mass, carbonizing the tire rubber sample, performing a first calcination and cooling in sequence to obtain ash and weighing the mass of the ash, recording it as the intermediate mass; step S2, mixing the first water and the ash to obtain the wetted ash; mixing the wetted ash with the first hydrofluoric acid and performing a first evaporation and cooling in sequence to obtain the first product; step S3, mixing the first product with the second water to obtain the second product; mixing the second product with the second hydrofluoric acid and performing a second evaporation, a second calcination and cooling in sequence to obtain the final product and weighing the mass of the final product, recording it as the final mass; step S4, taking the difference between the intermediate mass and the final mass as the mass of silica in the tire rubber sample, and calculating the mass content of silica in the tire rubber sample; step S5, when the tire rubber sample is n When the tire rubber test samples have different known silica mass contents, the tire rubber test samples are sequentially subjected to steps S1 to S4 to obtain the silica mass content test values corresponding to each tire rubber sample; the ratios of the silica mass content to the silica mass content test values in n tire rubber test samples are calculated, and the average value of the n ratios is obtained, which is recorded as A; wherein n ≥ 5; step S6, establishing a conversion formula between the silica mass content and the silica mass content in the tire rubber sample: silica mass content = A × silica mass content, where A is 1.07 to 1.13; step S7, when the tire rubber sample is a tire rubber test sample with an unknown silica mass content, the tire rubber test sample is sequentially subjected to steps S1 to S4 to obtain the silica mass content test value corresponding to the tire rubber test sample; the silica mass content test value is substituted into the conversion formula for calculation to obtain the silica mass content in the tire rubber test sample.

[0020] To address the issue of silica content not actually being equivalent to silica content, the present application first applies steps S1 to S4 to multiple tire rubber samples with known silica content, determining the coefficient relationship between silica content and silica content and establishing a conversion formula. Therefore, simply by measuring the silica content in the tire rubber sample according to steps S1 to S4 and calculating using the conversion formula described in this application, the silica content in the tire rubber sample can be determined. Furthermore, the present application's determination method not only significantly improves the accuracy of quantitative determination of silica content in tire rubber, but also offers broad applicability, applicable to tire rubber samples with varying silica content and silica grades. Steps S1 to S4 enable accurate determination of silica content. Specifically, in step S1, the tire rubber sample is carbonized until the ash becomes white, removing most of the organic matter. The first calcination thoroughly decomposes any remaining organic matter in the sample, yielding the ash content without affecting the ash composition. By adding hydrofluoric acid in step S2 and step S3, react with the silicon dioxide in the ash to generate silicon fluoride gas, can remove moisture by above-mentioned first evaporation and second evaporation, simultaneously make the silicon fluoride generated evaporate, thereby make the sample quality after drying more stable.In addition, adding water can prevent hydrofluoric acid from reacting too violently with ash.Can further remove a small amount of residual organic matter or reaction product by the second calcination, thereby improve the quality determination accuracy of final silicon dioxide.Can fully react with ash by adding hydrofluoric acid in batches, thereby improve the quality determination accuracy of final silicon dioxide.By step S4, the difference between intermediate mass and final mass / initial mass of tire rubber sample can obtain the mass content of silicon dioxide in tire rubber sample.

[0021] Preferably, n is 5-100, more preferably, n is 5-50, and even more preferably, n is 5-20.

[0022] In one embodiment of the present application, in the above step S1, the mass content of white carbon black in the tire rubber sample is 5-45%, and / or the specific surface area of white carbon black is 60-280 m 2 / g.

[0023] Preferably, the determination method of the present application can be applied to tire rubber samples with mass content and specific surface area within the above ranges, and has wide applicability.

[0024] In one embodiment of the present application, in the above step S1, the carbonization temperature is 200-300° C., and the carbonization time is 15-30 minutes.

[0025] Preferably, a certain mass of tire rubber sample is cut into small pellets, placed in a platinum crucible, and then carbonized on an electric furnace. Preferably, the carbonization temperature and time are within the above ranges to help fully remove organic matter from the tire rubber.

[0026] In one embodiment of the present application, in the above step S1, the temperature of the first calcination is 950-1000° C., and the time of the first calcination is 1-1.2 hours.

[0027] The temperature and time of the first calcination are preferably within the above ranges, which helps to fully decompose the residual organic matter in the sample and remove other impurities.

[0028] In one embodiment of the present application, in the above step S2, the volume of the first water is 2 to 5 mL; and / or the volume of the first hydrofluoric acid is 5 to 10 mL.

[0029] The volume of the first water is preferably controlled within the above range to facilitate sufficient wetting of the ash, thereby facilitating the reaction between the ash and the hydrofluoric acid. The volume of the first hydrofluoric acid is preferably controlled within the above range to facilitate conversion of silicon dioxide in the ash into silicon fluoride gas, thereby more accurately calculating the silicon dioxide content through mass loss.

[0030] In order to better remove moisture from the sample, in one embodiment of the present application, in the above step S2, the temperature of the first evaporation is 80-100° C., and the time of the first evaporation is 10-20 minutes.

[0031] Preferably, an electric furnace is used for the first evaporation until the sample is evaporated to dryness.

[0032] In one embodiment of the present application, in the above step S3, the volume of the second water is 1 to 3 mL; and / or the volume of the second hydrofluoric acid is 2 to 5 mL.

[0033] Preferably, the second water is used to flush the first product residue along the crucible wall. The volume of the second water is preferably controlled within the above-mentioned range to help moisten the hydrofluoric acid-insoluble matter in the first product, thereby facilitating its subsequent reaction with the second hydrofluoric acid. The volume of the second hydrofluoric acid is preferably controlled within the above-mentioned range to help promote the full reaction of unreacted silicon dioxide with the second hydrofluoric acid to form silicon fluoride gas, thereby facilitating accurate quantification of the silicon dioxide mass through subsequent mass changes.

[0034] In one embodiment of the present application, in the above step S3, the temperature of the second evaporation is 80-100° C., and the time of the second evaporation is 10-20 minutes.

[0035] It is preferable to control the temperature and time of the second evaporation within the above ranges, which helps to fully remove silicon fluoride and moisture.

[0036] In one embodiment of the present application, in the above step S3, the temperature of the second calcination is 950-1000° C., and the time of the second calcination is 1-1.2 hours.

[0037] It is preferred to control the temperature and time of the second calcination within the above ranges, which helps to fully remove the residues (especially organic substances) in the final product.

[0038] Preferably, the mass concentration of the first hydrofluoric acid and the second hydrofluoric acid is independently 450-500 g / L, which helps them to fully react with silicon dioxide, thereby improving the accuracy of silicon dioxide mass measurement.

[0039] In order to further improve the accuracy and precision of the determination of the mass content of silica, in one embodiment of the present application, A is 1.08 to 1.12.

[0040] Tire rubber samples used to determine the mass content of silica can be vulcanized rubber or mixed rubber, which helps to improve the reliability and reproducibility of the determination of silica mass content.

[0041] In one embodiment of the present application, the tire rubber sample further comprises, by weight, 100 parts of rubber, 1.0 to 7.0 parts of an activator, 1.0 to 5.0 parts of an antioxidant, 0.5 to 2.5 parts of an accelerator, and 0.8 to 4.0 parts of a vulcanizing agent; and / or, the tire rubber sample further comprises 0.1 to 0.3 parts of a scorch retarder.

[0042] The determination method of the present application can be applied to most tire rubber types and has a wide range of applications. Preferably, the rubber is selected from any one or more of natural rubber (NR), styrene-butadiene rubber (SBR), butadiene rubber (BR), and ethylene-propylene rubber (EMP). The activator is zinc oxide and / or stearic acid. The antioxidant is antioxidant 4010 / RD and / or protective wax. The accelerator is accelerator CZ and / or accelerator NS. The vulcanizing agent is sulfur.

[0043] In one embodiment of the present application, the grade of white carbon black is selected from any one or more of 80GR, 200MP, 1125MP, LK975, 7000GR and 1165MP.

[0044] The determination method of the present application is applicable to tire rubber with different silica grades, and is not limited to the above-mentioned grades, and has good applicability.

[0045] The beneficial effects of the present application will be further illustrated below with reference to examples.

[0046] The determination method of silica in the vulcanized rubber samples (vulcanized rubber test products and vulcanized rubber test products) in the following Examples 1 to 19 is the same. The raw material components and weight proportions of the rubber composition in the vulcanized rubber test products are the same as those of the vulcanized rubber test product 1. The difference lies in the different actual mass contents of carbon black in the vulcanized rubber test products (the mass contents of carbon black in Examples 1 to 5 are 31.5%, 29.3%, 29.3%, 26.7%, and 26.7%, respectively; the mass contents of carbon black in Examples 6 to 10 are 17.4%, 11.7%, 11.7%, 11.7%, and 11.7%, respectively; the mass contents of carbon black in Examples 11 to 15 are 11.7%, 5.9%, 5.7%, 5.4%, and 5.2%, respectively; and the mass contents of carbon black in Examples 16 to 19 are 4.8%, 4.6%, 3.0%, and 3.0%, respectively) and the different grades and actual mass contents of silica. See Table 1 for details. The actual mass content of silica is recorded as the theoretical mass content of silica.

[0047] Preparation of vulcanized rubber samples: The rubber composition, by weight, consists of 100 parts of NR rubber, 10 parts of white carbon black, 56 parts of carbon black, 2.0 parts of stearic acid as an activator, 4.0 parts of zinc oxide, 1.5 parts of antioxidant 4020, 1.0 parts of antioxidant RD, 1.2 parts of accelerator NS, and 2.2 parts of sulfur as a vulcanizing agent. The above rubber composition undergoes first-stage mixing, second-stage mixing, and vulcanization to obtain vulcanized rubber sample 1. The formulations of vulcanized rubber samples 1 to 5 are shown in Table 2. The white carbon black grades used in vulcanized rubber samples 1 to 5 are 80GR, 200MP, 1125MP, LK975, and 7000GR, respectively. Vulcanized rubber sample 2, vulcanized rubber sample 3, vulcanized rubber sample 4, vulcanized rubber sample 5, and the vulcanized rubber sample to be tested were prepared according to the above vulcanized rubber sample preparation method.

[0048] Silica mass measurement:

[0049] In step S1, 1.1354 g of a vulcanized rubber sample was weighed and recorded as the initial mass. The vulcanized rubber sample was cut into small pellets, placed in a platinum crucible, and carbonized on an electric furnace at 300°C for 20 minutes until the ash turned white. The sample was then transferred to a muffle furnace and calcined at 950°C for 1 hour. After cooling, the ash was obtained and weighed. The total weight of the ash and the crucible was 27.1169 g, recorded as the intermediate mass.

[0050] Step S2, add 3mL of the first water to the crucible to moisten the ash to obtain the wetted ash. 5mL of the first hydrofluoric acid with a mass concentration of 450g / L is added to the moistened ash to react and generate silicon fluoride gas, and an electric furnace is used to perform a first evaporation at 90°C until it is evaporated to dryness, and a first product is obtained after cooling. Step S3, 2mL of the second water is added to the first product again, the first product residue is flushed down along the crucible wall, 3mL of the second hydrofluoric acid with a mass concentration of 450g / L is added to react and generate silicon fluoride gas, followed by a second evaporation at 90°C until it is evaporated to dryness, transferred to a muffle furnace and calcined for a second time at 950°C for 1h, and a final product is obtained after cooling. The total weight of the final product and the crucible is weighed to be 27.0594g, which is recorded as the final mass.

[0051] Step S4: The difference between the intermediate mass and the final mass is used as the mass of silicon dioxide in the vulcanized rubber sample, and the mass content of silicon dioxide is calculated using the formula: the mass content of silicon dioxide in the vulcanized rubber sample is (intermediate mass-final mass) / initial mass.

[0052] When the vulcanized rubber samples are vulcanized rubber test samples 1 to 5, the above steps S1 to S4 are sequentially performed, and the corresponding silica mass content test values are 5.1%, 7.6%, 7.7%, 9.8%, and 10.1%, respectively. The mass content of silica in the vulcanized rubber test samples 1 to 5 is 5.6%, 8.4%, 8.4%, 11.1%, and 11.1%, respectively.

[0053] The ratios of the test values of the mass content of white carbon black and the mass content of silicon dioxide in tire rubber test samples 1 to 5 were calculated and were 1.10, 1.11, 1.09, 1.13 and 1.10, respectively. The average of the five ratios was obtained and recorded as A, where A was 1.1.

[0054] The conversion formula between the mass content of white carbon black and the mass content of silicon dioxide in the vulcanized rubber sample was established as mass content of white carbon black = 1.1 × mass content of silicon dioxide.

[0055] When the vulcanized rubber sample is a vulcanized rubber product to be tested, the above steps S1 to S4 are sequentially performed to obtain the corresponding silica mass content test value. The silica mass content test value of the vulcanized rubber product to be tested is substituted into the conversion formula to calculate the silica mass content in the vulcanized rubber product to be tested, and recorded as the silica mass content measured value.

[0056] Example 20

[0057] The difference from Example 1 is that the mass of silicon dioxide is measured:

[0058] In step S1, 1.2897 g of a vulcanized rubber sample was weighed and recorded as the initial mass. The vulcanized rubber sample was cut into small pellets, placed in a platinum crucible, and carbonized on an electric furnace at 250°C for 15 minutes until the ash turned white. The sample was then transferred to a muffle furnace and calcined at 980°C for 1.1 hours. After cooling, the ash was obtained and weighed. The total weight of the ash and the crucible was 27.2940 g, recorded as the intermediate mass.

[0059] Step S2, add 1mL of the first water to the crucible to moisten the ash to obtain the wetted ash. 8mL of the first hydrofluoric acid with a mass concentration of 480g / L is added to the wetted ash to react and generate silicon fluoride gas, and an electric furnace is used to perform the first evaporation at 80°C until it is evaporated to dryness, and the first product is obtained after cooling. Step S3, 2mL of the second water is added to the first product again, the first product residue is flushed down along the crucible wall, 5mL of the second hydrofluoric acid with a mass concentration of 480g / L is added to react and generate silicon fluoride gas, followed by a second evaporation at 80°C until it is evaporated to dryness, transferred to a muffle furnace and calcined for a second time at 980°C for 1.2h, and the final product is obtained after cooling, and the total weight of the final product and the crucible is weighed to be 27.2295g, which is recorded as the final mass.

[0060] Step S4: The difference between the intermediate mass and the final mass is used as the mass of silicon dioxide in the vulcanized rubber sample, and the mass content of silicon dioxide is calculated using the formula: the mass content of silicon dioxide in the vulcanized rubber sample is (intermediate mass-final mass) / initial mass.

[0061] When the vulcanized rubber samples are vulcanized rubber test samples 1 to 5, the above steps S1 to S4 are sequentially performed, and the corresponding silica mass content test values are 5.0%, 7.4%, 7.4%, 9.7%, and 10.0%, respectively. The mass content of silica in the vulcanized rubber test samples 1 to 5 is 5.6%, 8.4%, 8.4%, 11.1%, and 11.1%, respectively.

[0062] The ratios of the test values of the mass content of white carbon black and the mass content of silicon dioxide in tire rubber test samples 1 to 5 were calculated and were 1.12, 1.14, 1.14, 1.14 and 1.11, respectively. The average of the five ratios was obtained and recorded as A, which was 1.13.

[0063] The conversion formula between the mass content of white carbon black and the mass content of silicon dioxide in the vulcanized rubber sample was established as mass content of white carbon black = 1.13 × mass content of silicon dioxide.

[0064] When the vulcanized rubber sample is a vulcanized rubber product to be tested, the above steps S1 to S4 are sequentially performed to obtain the corresponding silica mass content test value. The silica mass content test value of the vulcanized rubber product to be tested is substituted into the conversion formula to calculate the silica mass content in the vulcanized rubber product to be tested, and recorded as the silica mass content measured value.

[0065] Example 21

[0066] The difference from Example 1 is that the mass of silicon dioxide is measured:

[0067] In step S1, 1.3275 g of a vulcanized rubber sample was weighed and recorded as the initial mass. The vulcanized rubber sample was cut into small pellets, placed in a platinum crucible, and carbonized on an electric furnace at 200°C for 30 minutes until the ash turned white. The sample was then transferred to a muffle furnace and calcined at 1000°C for 1.1 hours. After cooling, the ash was obtained and weighed. The total weight of the ash and the crucible was 27.0868 g, recorded as the intermediate mass.

[0068] Step S2, add 5mL of the first water to the crucible to moisten the ash to obtain the wetted ash. 10mL of the first hydrofluoric acid with a mass concentration of 500g / L is added to the wetted ash to react and generate silicon fluoride gas, and an electric furnace is used to perform a first evaporation at 100°C until it is evaporated to dryness, and a first product is obtained after cooling. Step S3, 3mL of the second water is added to the first product again, the first product residue is flushed down along the crucible wall, 5mL of the second hydrofluoric acid with a mass concentration of 500g / L is added to react and generate silicon fluoride gas, followed by a second evaporation at 100°C until it is evaporated to dryness, transferred to a muffle furnace and calcined for a second time at 950°C for 1h, and a final product is obtained after cooling. The total weight of the final product and the crucible is weighed to be 27.0164g, which is recorded as the final mass.

[0069] Step S4: The difference between the intermediate mass and the final mass is used as the mass of silicon dioxide in the vulcanized rubber sample, and the mass content of silicon dioxide is calculated using the formula: the mass content of silicon dioxide in the vulcanized rubber sample is (intermediate mass-final mass) / initial mass.

[0070] When the vulcanized rubber samples are vulcanized rubber test samples 1 to 5, the above steps S1 to S4 are sequentially performed, and the corresponding silica mass content test values are 5.3%, 7.8%, 7.0%, 10.2%, and 10.4%, respectively. The mass content of silica in the vulcanized rubber test samples 1 to 5 is 5.6%, 8.4%, 8.4%, 11.1%, and 11.1%, respectively.

[0071] The ratios of the test values of the mass content of white carbon black and the mass content of silicon dioxide in tire rubber test samples 1 to 5 were calculated and were 1.05, 1.08, 1.06, 1.09 and 1.07, respectively. The average of the five ratios was obtained and recorded as A, which was 1.07.

[0072] The conversion formula between the mass content of white carbon black and the mass content of silicon dioxide in the vulcanized rubber sample was established as mass content of white carbon black = 1.07 × mass content of silicon dioxide.

[0073] When the vulcanized rubber sample is a vulcanized rubber product to be tested, the above steps S1 to S4 are sequentially performed to obtain the corresponding silica mass content test value. The silica mass content test value of the vulcanized rubber product to be tested is substituted into the conversion formula to calculate the silica mass content in the vulcanized rubber product to be tested, and recorded as the silica mass content measured value.

[0074] Comparative Example 1

[0075] The difference from Example 1 is that the silica mass content test value of the vulcanized rubber sample to be tested is substituted into the conversion formula: mass content of white carbon black = 1.5 × mass content of silicon dioxide, and the mass content of white carbon black in the vulcanized rubber sample to be tested is calculated and recorded as the measured mass content of white carbon black.

[0076] Test method:

[0077] Recovery rate = measured value of silica mass content in the vulcanized rubber sample / theoretical value of silica mass content * 100, which is used to evaluate the accuracy and reliability of the determination method. The results are shown in Table 1.

[0078] Table 1

[0079]

[0080]

[0081] Table 2

[0082]

[0083]

[0084] As can be seen from the data in Table 1, the recovery rate of Comparative Example 1 is 138%, which is significantly different from its actual content (theoretical value of silica mass content). In contrast, the recovery rates of the examples in the present application are 97-104%. This shows that the difference between the silica mass content obtained according to the conversion formula in the determination method of the present application and its actual content (theoretical value of silica mass content) is relatively small, demonstrating that the determination method of the present application has high accuracy and reliability.

[0085] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0086] To address the issue of silica content not actually being equivalent to silica content, the present application first applies steps S1 to S4 to multiple tire rubber samples with known silica content, determining the coefficient relationship between silica content and silica content and establishing a conversion formula. Therefore, simply by measuring the silica content in the tire rubber sample according to steps S1 to S4 and calculating using the conversion formula described in this application, the silica content in the tire rubber sample can be determined. Furthermore, the present application's determination method not only significantly improves the accuracy of quantitative determination of silica content in tire rubber, but also offers broad applicability, applicable to tire rubber samples with varying silica content and silica grades. Steps S1 to S4 enable accurate determination of silica content. Specifically, in step S1, the tire rubber sample is carbonized until the ash becomes white, removing most of the organic matter. The first calcination thoroughly decomposes any remaining organic matter in the sample, yielding the ash content without affecting the ash composition. By adding hydrofluoric acid in step S2 and step S3, react with the silicon dioxide in the ash to generate silicon fluoride gas, can remove moisture by above-mentioned first evaporation and second evaporation, simultaneously make the silicon fluoride generated evaporate, thereby make the sample quality after drying more stable.In addition, adding water can prevent hydrofluoric acid from reacting too violently with ash.Can further remove a small amount of residual organic matter or reaction product by the second calcination, thereby improve the quality determination accuracy of final silicon dioxide.Can fully react with ash by adding hydrofluoric acid in batches, thereby improve the quality determination accuracy of final silicon dioxide.By step S4, the difference between intermediate mass and final mass / initial mass of tire rubber sample can obtain the mass content of silicon dioxide in tire rubber sample.

[0087] The above are merely embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for determining the mass content of white carbon black in tire rubber, characterized in that: The determination method comprises: Step S1, weighing the mass of the tire rubber sample and recording it as the initial mass, carbonizing, first calcining and cooling the tire rubber sample in sequence to obtain ash and weighing the mass of the ash and recording it as the intermediate mass; Step S2, mixing the first water and the ash to obtain wetted ash; mixing the wetted ash with the first hydrofluoric acid, and then performing a first evaporation and cooling in sequence to obtain a first product; Step S3, mixing the first product and the second water to obtain a second product; mixing the second product with the second hydrofluoric acid, and then sequentially performing a second evaporation, a second calcination, and cooling to obtain a final product, and weighing the mass of the final product, which is recorded as the final mass; Step S4, taking the difference between the intermediate mass and the final mass as the mass of the silicon dioxide in the tire rubber sample, and calculating the mass content of the silicon dioxide in the tire rubber sample; Step S5: When the tire rubber sample is n different tire rubber test samples with known silica mass content, the tire rubber test samples are sequentially subjected to steps S1 to S4 to obtain the silica mass content test value corresponding to each of the tire rubber samples; the ratio of the silica mass content to the silica mass content test value in the n tire rubber test samples is calculated, and the average value of the n ratios is obtained, which is recorded as A; wherein, n≥5； Step S6, establishing a conversion formula between the mass content of white carbon black and the mass content of silicon dioxide in the tire rubber sample: mass content of white carbon black = A × mass content of silicon dioxide, where A is 1.07 to 1.13; Step S7: When the tire rubber sample is a tire rubber product to be tested with an unknown silica mass content, the tire rubber product to be tested sequentially undergoes steps S1 to S4 to obtain a silica mass content test value corresponding to the tire rubber product to be tested; the silica mass content test value is substituted into the conversion formula for calculation to obtain the silica mass content in the tire rubber product to be tested.

2. The measuring method according to claim 1, wherein In step S1, the mass content of white carbon black in the tire rubber sample is 5-45%, and / or the specific surface area of white carbon black in the tire rubber sample is 60-280 m 2 / g.

3. The measuring method according to claim 1 or 2, characterized in that In the step S1, the carbonization temperature is 200-300° C., and the carbonization time is 15-30 minutes.

4. The measuring method according to any one of claims 1 to 3, characterized in that In the step S1, the temperature of the first calcination is 950-1000° C., and the time of the first calcination is 1-1.2 hours.

5. The measuring method according to any one of claims 1 to 4, characterized in that In step S2, the volume of the first water is 2 to 5 mL; and / or the volume of the first hydrofluoric acid is 5 to 10 mL.

6. The measuring method according to any one of claims 1 to 5, characterized in that In the step S2, the temperature of the first evaporation is 80-100°C, and the time of the first evaporation is 10-20 minutes.

7. The measuring method according to any one of claims 1 to 6, characterized in that In step S3, the volume of the second water is 1 to 3 mL; and / or the volume of the second hydrofluoric acid is 2 to 5 mL.

8. The measuring method according to any one of claims 1 to 7, characterized in that In step S3, the temperature of the second evaporation is 80-100° C., and the time of the second evaporation is 10-20 minutes; and / or the temperature of the second calcination is 950-1000° C., and the time of the second calcination is 1-1.2 hours.

9. The measuring method according to any one of claims 1 to 8, characterized in that In the step S3, the temperature of the second calcination is 950-1000° C., and the time of the second calcination is 1-1.2 hours.

10. The measuring method according to any one of claims 1 to 9, characterized in that The A is 1.08 to 1.12.

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