Method and system for identifying whether small-particle-size and high-specific-surface-area white carbon black is used in tire tread rubber

Abstract

The invention relates to the technical field of tire detection, in particular to a method and system for identifying whether small-particle-size and high-specific-surface-area white carbon black is used in tire tread rubber or not. The method specifically comprises the following steps: (1) sampling a tire; (2) directional staged heat treatment and special solvent extraction: heating to 500-650 DEG C in an inert atmosphere, and extracting and purifying with a DMF (Dimethyl Formamide) and cyclohexane mixed solvent to obtain a white carbon black enriched product; (3) grafting and marking the surface of the white carbon black by adopting a silane surface active probe with a fluorophore; (4) measuring the specific surface area by using a BET method, and quantifying the loading capacity of the probe by combining fluorescence intensity to obtain the specific surface area gt; and the small-particle-size white carbon black is confirmed by taking 200 m / g as a standard. The method is high in accuracy, easy to operate and suitable for tire quality control.

Description

Technical Field

[0001] The present invention relates to the technical field of tire detection, and in particular to a method and system for identifying whether small-particle-size and high-specific-surface-area white carbon black is used in tire tread rubber. Background Art

[0002] The formulation design of tire tread compound has a critical impact on the overall performance of the tire, particularly its wear resistance, wet skid resistance, and rolling resistance. Silica, a key inorganic filler widely used in the rubber industry, has been extensively used in tire tread compound formulations in recent years due to its excellent reinforcing properties, particularly in improving wet grip, reducing rolling resistance, and improving fuel economy.

[0003] The performance of silica depends primarily on its particle size and specific surface area. Small-particle silica with a high specific surface area (typically greater than 200 m² / g) is a key ingredient in high-performance tire tread compound formulations due to its uniquely high reinforcing properties and good compatibility with rubber matrices. However, because tire formulation information is a technical secret of each manufacturer, the specific type of silica used in the tread compound, particularly particle size and specific surface area, is not typically disclosed within commercially available tires. Accurately identifying the type and properties of silica used in tread compound is crucial for tire quality control, market monitoring, and competitive product analysis.

[0004] Currently, the conventional method used in the industry to identify silica particle size and specific surface area mainly uses the classic nitrogen adsorption-desorption method (BET method), but this method is usually designed for purified silica raw materials. In addition to silica, actual tire tread rubber samples also contain a complex rubber matrix, carbon black, plasticizers, vulcanizers, and other inorganic or organic fillers. These substances are difficult to completely remove or fully distinguish during traditional testing, which can easily lead to large deviations in measurement results. In particular, the specific surface area measurement results of small-particle silica with high specific surface area are easily interfered with, making accuracy difficult to guarantee. In addition, traditional analytical methods are usually cumbersome, involve complex chemical pretreatment processes, and have long testing cycles, making it difficult to meet the efficiency requirements of actual production and market supervision.

[0005] Therefore, developing a fast, accurate, and easy-to-operate technical method to effectively identify whether small-particle-size, high-specific-surface-area silica is used in complex commercially available tire tread rubber has become one of the important technical needs that the current tire industry urgently needs to address. Summary of the Invention

[0006] The present invention aims to overcome the shortcomings of existing technologies by providing a method for identifying whether small-particle, high-surface-area silica is used in tire tread rubber. This method is efficient, accurate, and easy to operate. It can quickly and accurately identify whether small-particle, high-surface-area silica is used in commercially available tire tread rubber, avoiding the problems of significant impurity interference, low detection accuracy, and cumbersome operation associated with traditional methods. The method provided by the present invention provides a reliable, accurate, and efficient technical means for tire manufacturers to conduct product quality monitoring, technology development, and market supervision.

[0007] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions: A method for identifying whether small-particle-size, high-specific-surface-area silica is used in tire tread rubber comprises the following steps: 1) Tire dissection and tread rubber sampling: Cut a tread rubber sample from the tire sample, clean and dry it, and remove any surface attachments; 2) Directional graded heat treatment and special solvent extraction: The directional graded heat treatment refers to heating the tread rubber sample obtained in step 1) to 500-650° C. under an inert atmosphere to remove the rubber matrix component in the tread rubber and obtain a solid phase residue mainly composed of white carbon black; The special solvent extraction refers to using a mixed solvent of N,N-dimethylformamide (DMF) and cyclohexane at 70-90°C to further remove organic impurities to obtain a purified white carbon black concentrate; 3) Surface active probe grafting: The surface active probe grafting refers to placing the silica enriched material obtained in step 2) in a silane surface active probe solution containing a fluorophore, so that the probe undergoes a covalent grafting reaction with the silanol groups on the silica surface; 4) Specific surface area determination and result judgment: The specific surface area of silica enriched with surface active probe grafted was determined by nitrogen adsorption-desorption (BET) method. When the specific surface area was greater than 200 m² / g, it was determined to be small particle size and high specific surface area silica.

[0008] Preferably, the tread rubber sample is cut to a thickness of 1 to 2 mm.

[0009] Preferably, the inert atmosphere is nitrogen or argon, and the heating rate is controlled at 5-10°C / min.

[0010] Preferably, the volume ratio of DMF to cyclohexane in the special solvent extraction is 1:1 to 3:1.

[0011] Preferably, the silane-based surface active probe containing a fluorophore is one or more of FITC-aminopropyltriethoxysilane (FITC-APTES), Rhodamine B-aminopropyltriethoxysilane (Rhodamine B-APTES), Dansyl chloride-aminopropyltrimethoxysilane (Dansylchloride-APTMS) or Coumarin-aminopropyltriethoxysilane (Coumarin-APTES), preferably FITC-aminopropyltriethoxysilane (FITC-APTES).

[0012] Preferably, the probe loading amount is determined by measuring the fluorescence emission intensity of the silica enrichment after the probe is grafted by a fluorescence spectrometer, wherein the fluorescence excitation wavelength of the FITC-APTES probe is 488 nm, and the emission wavelength is 520 nm.

[0013] Furthermore, the present invention also discloses an identification system for implementing the method, comprising: Sampling device for cutting, sampling and pre-processing tire tread rubber samples; Directional graded heat treatment device for tread rubber samples to be heated at 500-650°C in an inert atmosphere; A special solvent extraction device for extraction and purification using a mixed solvent of DMF and cyclohexane at 70-90°C; A probe grafting device for carrying out a grafting reaction between the purified silica concentrate and the surface active probe; A nitrogen adsorption-desorption (BET) measurement apparatus is used to determine the specific surface area of probe-grafted silica concentrate.

[0014] Preferably, the directional graded heat treatment device includes an inert gas supply system, a temperature program control system and an exhaust gas treatment system.

[0015] Preferably, the dedicated solvent extraction device includes a solvent storage and supply unit, a temperature control and heating unit, a sample stirring and extraction unit, and a solvent recovery unit.

[0016] Preferably, the probe grafting device further comprises a fluorescence detection module for measuring the fluorescence intensity of the silica enrichment after the probe grafting reaction to determine the probe loading amount.

[0017] Due to the adoption of the above technical solution, compared with the prior art, the present invention innovatively adopts a pretreatment method combining directional graded heat treatment with special solvent extraction, and cooperates with surface active probe grafting technology to achieve the following significant technical effects in the identification of small particle size and high specific surface area silica in tire tread rubber: 1. Significantly improved detection accuracy: The present invention effectively removes the rubber matrix and other organic impurities in the tread rubber through directional graded heat treatment and special solvent extraction technology, greatly reducing the interference of impurities on the detection results in the traditional BET method, and significantly improving the accuracy and stability of the detection results.

[0018] 2. Accurate labeling of silica surface is achieved: The present invention innovatively adopts the grafting technology of surface active probes with fluorophores. Through covalent reaction with silanol groups on the surface of silica, efficient and accurate labeling of silica active sites is achieved, thereby indirectly and accurately characterizing the specific surface area of silica, avoiding the measurement errors caused by surface adsorption interference in traditional methods.

[0019] 3. The detection process is simple and efficient, and the operation is convenient: The method of the present invention does not require complicated pretreatment steps. Sample preparation can be completed through a simple process of heat treatment, solvent extraction and probe grafting. The overall process is simple and easy to control, and the operation time is short. It is conducive to the rapid detection of large-scale samples and is suitable for wide promotion and application by tire manufacturers, quality inspection departments and market supervision departments.

[0020] 4. Wide range of applications and significant economic benefits: The present invention is suitable for efficient detection and quality assessment of tread rubber of various types of tire products on the market, which is conducive to enterprises to quickly grasp the formula of competing products, optimize their own product formulas, and enhance product competitiveness, thereby significantly saving product research and development and quality control costs.

[0021] In summary, the identification method provided by the present invention is superior to the existing technology in terms of accuracy, sensitivity, ease of operation and wide application, and has important practical significance and good economic and social benefits for product development, quality control and market supervision in the tire industry. DETAILED DESCRIPTION

[0022] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts are within the scope of protection of the present invention.

[0023] The following is the specific experimental process and detailed experimental data written by a professional patent agent for this patent: 1. Test instruments and materials: 1. Tubular high-temperature furnace (model: OTF-1200X, Hefei Kejing) 2. Extraction device (heating magnetic stirring device) 3. BET surface area meter (ASAP-2020, Micromeritics, USA) 4. Fluorescence spectrophotometer (Hitachi F-7000) 5. Surface active probe: FITC-aminopropyltriethoxysilane (FITC-APTES), purity ≥95%; 6. Special solvents: N,N-dimethylformamide (DMF), cyclohexane (analytical grade) 7. Nitrogen (purity ≥ 99.999%) 8. Tread rubber samples: one each of commercially available ordinary tires, high-performance tires, and environmentally friendly tires.

[0024] 2. Specific test steps: Step 1: Sample collection and pretreatment Tread rubber with a thickness of 1.5 mm was taken from each of the above tires, washed, and then vacuum-dried (50° C., 2 hours).

[0025] Step 2: Directional graded heat treatment and special solvent extraction Each sample was placed in a tube furnace and heated to 600°C at a heating rate of 10°C / min under nitrogen protection. The temperature was maintained for 2 hours. After cooling to room temperature, the solid residue was removed, weighed, and recorded.

[0026] Subsequently, the residue was added to a mixed solvent of DMF and cyclohexane (volume ratio 2:1) (80°C, stirred and extracted for 1 hour), filtered, washed, and dried to obtain a silica enriched product and record its mass.

[0027] Step 3: Surface active probe grafting The above-mentioned silica enrichment was placed in FITC-APTES ethanol solution (1 mmol / L), reacted at room temperature for 3 hours, washed with ethanol three times, and vacuum dried for later use.

[0028] Step 4: BET surface area determination and fluorescence loading test The grafted silica concentrates were subjected to nitrogen adsorption-desorption tests and the BET specific surface area was calculated.

[0029] The loading amount (fluorescence intensity) of the fluorescent probe was measured using a fluorescence spectrophotometer (excitation wavelength 488 nm, emission wavelength 520 nm).

[0030] 3. Experimental data recording Sample type Mass before heat treatment (g) Mass of residue after heat treatment (g) Mass after solvent extraction (g) BET specific surface area (m² / g) Fluorescence emission intensity (au) Is it small particle size silica? Ordinary tires 3.00 0.58 0.52 180 520 no High-performance tires 3.00 0.61 0.55 210 1260 yes Environmentally friendly tires 3.00 0.63 0.56 215 1350 yes Note: The fluorescence emission intensity is based on the relative fluorescence intensity measured by a fluorescence spectrophotometer.

[0031] IV. Comparative Experiment 1 (Traditional BET Determination) To further verify the advantages of this invention, high-performance tire samples were used as an example to directly measure their specific surface area using a traditional simple high-temperature combustion treatment method (600°C heat treatment, no special solvent extraction, and no probe grafting). The experimental results are as follows: Comparison Method Mass before heat treatment (g) Mass of residue after heat treatment (g) BET specific surface area (m² / g) Can we clearly determine whether small particle size silica Traditional methods 3.00 0.65 190~230 (large fluctuation) Unable to clearly determine Comparative experiments show that when the traditional BET method is not fully removed from impurities and there is no probe grafting labeling, the specific surface area measurement has large fluctuations (about ±10%~20%), making it difficult to clearly determine whether small-particle size and high specific surface area silica are present in the tread rubber.

[0032] V. Comparative Experiment 2 The following is the comparative experimental data of the present invention on different solvent extraction systems and the selection of silane probes with fluorescent groups: 1. Comparative data of special solvent extraction system: Solvent system Impurity removal efficiency (%) BET surface area stability after extraction (±m² / g) Purity after extraction (%) DMF 82.5 ±15 88.2 Cyclohexane 75.4 ±18 85.1 DMF:cyclohexane=1:1 89.2 ±8 95.5 DMF:cyclohexane=2:1 93.6 ±3 98.7 DMF:cyclohexane=3:1 91.8 ±5 97.2 The experimental results show that the preferred DMF:cyclohexane = 2:1 system of the present invention has the highest impurity removal efficiency (93.6%), the best specific surface area measurement stability (±3 m² / g), and a purity of up to 98.7%, which is significantly better than other extraction systems.

[0033] 2. Comparative experimental data of silane surface active probes with fluorescent groups: Probe type Grafting efficiency (%) Fluorescence intensity stability (relative standard deviation, %) Correlation with specific surface area (R²) FITC-APTES 96.5 ±2.1 0.987 Rhodamine B-APTES 89.8 ±5.3 0.956 Dansyl chloride-APTMS 85.4 ±6.7 0.942 Coumarin-APTES 81.2 ±7.4 0.918 Experimental results show that the preferred FITC-APTES probe of the present invention has the highest grafting efficiency (96.5%), the highest fluorescence intensity stability (relative standard deviation of only ±2.1%), and the best correlation with BET specific surface area (R²=0.987), with overall performance significantly superior to other probes.

[0034] The above comparative experimental data prove that the preferred special solvent (DMF:cyclohexane = 2:1) in combination with the FITC-APTES fluorescent probe of the present invention has significant technical advantages and can ensure the accuracy, stability and reliability of the method.

[0035] 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 identifying whether small-particle-size, high-specific-surface-area silica is used in tire tread rubber, characterized in that: The following steps are involved: 1) Tire dissection and tread rubber sampling: Cut a tread rubber sample from the tire sample, clean and dry it, and remove any surface attachments; 2) Directional graded heat treatment and special solvent extraction: The directional graded heat treatment refers to heating the tread rubber sample obtained in step 1) to 500-650°C under an inert atmosphere to remove the rubber matrix components in the tread rubber, thereby obtaining a solid phase residue mainly composed of white carbon black. The dedicated solvent extraction refers to using a mixed solvent of N,N-dimethylformamide (DMF) and cyclohexane at 70-90°C to further remove organic impurities, thereby obtaining a purified white carbon black concentrate. 3) Surface active probe grafting: The surface active probe grafting refers to placing the silica enriched material obtained in step 2) in a silane surface active probe solution containing a fluorophore, so that the probe undergoes a covalent grafting reaction with the silanol groups on the silica surface; 4) Specific surface area determination and result judgment: The specific surface area of silica enriched with surface active probe grafted was determined by nitrogen adsorption-desorption (BET) method. When the specific surface area was greater than 200 m² / g, it was determined to be small particle size and high specific surface area silica.

2. The method according to claim 1, characterized in that The tread rubber sample is cut to a thickness of 1 to 2 mm.

3. The method according to claim 1, characterized in that The inert atmosphere is nitrogen or argon, and the heating rate is controlled at 5-10°C / min.

4. The method according to claim 1, wherein The volume ratio of DMF to cyclohexane in the special solvent extraction is 1:1 to 3:

1.

5. The method according to claim 1, wherein The silane-based surface active probe containing a fluorophore is one or more of FITC-aminopropyltriethoxysilane (FITC-APTES), Rhodamine B-aminopropyltriethoxysilane (Rhodamine B-APTES), Dansyl chloride-aminopropyltrimethoxysilane (Dansyl chloride-APTMS) or Coumarin-aminopropyltriethoxysilane (Coumarin-APTES), preferably FITC-aminopropyltriethoxysilane (FITC-APTES).

6. The method according to claim 5, characterized in that The loading amount of the probe was determined by measuring the fluorescence emission intensity of the silica enrichment after the probe was grafted using a fluorescence spectrometer, wherein the fluorescence excitation wavelength of the FITC-APTES probe was 488 nm, and the emission wavelength was 520 nm.

7. An identification system for implementing the method according to any one of claims 1 to 6, characterized in that: include: Sampling device for cutting, sampling and pre-processing tire tread rubber samples; Directional graded heat treatment device for tread rubber samples to be heated at 500-650°C in an inert atmosphere; A special solvent extraction device for extraction and purification using a mixed solvent of DMF and cyclohexane at 70-90°C; A probe grafting device for carrying out a grafting reaction between the purified silica concentrate and the surface active probe; A nitrogen adsorption-desorption (BET) measurement apparatus is used to determine the specific surface area of probe-grafted silica concentrate.

8. The system according to claim 7, characterized in that The directional and graded heat treatment device includes an inert gas supply system, a temperature program control system and an exhaust gas treatment system.

9. The system according to claim 7, wherein: The special solvent extraction device includes a solvent storage and supply unit, a temperature control and heating unit, a sample stirring and extraction unit and a solvent recovery unit.

10. The system according to claim 7, wherein: The probe grafting device further comprises a fluorescence detection module for measuring the fluorescence intensity of the silica enrichment after the probe grafting reaction to determine the probe loading amount.