Methods and applications for determining the ratio of cis-butadiene rubber and styrene-butadiene rubber in rubber

Abstract

This invention relates to the field of chemical analysis technology, and discloses a method and its application for determining the ratio of cis-butadiene rubber and styrene-butadiene rubber (SBR) in rubber. This method is based on solid-state nuclear magnetic resonance (NMR) to obtain the percentage of each functional group. Then, by applying the fundamental theory that the ratio of cis to trans content of the groups closest to styrene and vinyl groups in SBR is equal to the ratio of the total cis to trans content in the SBR, this method achieves precise analysis of the ratio of cis-butadiene rubber and SBR, effectively solving the problem that existing technologies cannot accurately distinguish between these two types of rubber, thus improving the accuracy and efficiency of the analysis. Furthermore, this method has wide applicability, a simple and rapid analytical process, and significant commercial value.

Description

Technical Field

[0001] This invention relates to the field of chemical analysis technology, and more specifically, to a method and application for determining the ratio of cis-butadiene rubber and styrene-butadiene rubber in rubber. Background Technology

[0002] In the field of polymer materials, especially in tire manufacturing, tire performance largely depends on its internal rubber formulation. Cis-butadiene rubber (BR) and styrene-butadiene rubber (SBR) are two commonly used rubber types, indispensable in many tire formulations. However, the formulations of these rubbers, particularly the ratio between the two, are highly confidential trade secrets and are typically not disclosed. In the field of chemical analysis, nuclear magnetic resonance (NMR) is an important analytical tool used to determine the molecular structure and composition of polymer materials. By analyzing the carbon composition of different functional groups, the proportions of the rubber can be inferred. However, because both cis-butadiene rubber and styrene-butadiene rubber contain cis-butadiene monomers in their structural units, it is difficult to distinguish between the two using existing techniques.

[0003] Existing solutions primarily utilize solid-state NMR to obtain the percentage of each functional group, thereby deducing the rubber proportion in the formulation. While this method provides valuable information about rubber formulations, it cannot precisely distinguish between cis-butadiene rubber (CBR) and styrene-butadiene rubber (SBR) due to their structural similarities. Although CBR has some effectiveness in analyzing rubber formulations, it suffers from significant limitations. The most significant problem is its inability to accurately differentiate between CBR and SBR. These two rubbers have very similar structures, both containing CBR monomers, making it difficult to obtain their precise proportions using existing NMR techniques. Furthermore, the presence of other components in the formulation, such as fillers and additives, further complicates the analysis. Therefore, accurately analyzing the proportions of CBR and SBR in tire rubber formulations remains a pressing problem in this field. Summary of the Invention

[0004] This invention addresses the shortcomings of existing technologies by providing a method and application for determining the ratio of cis-butadiene rubber and styrene-butadiene rubber in rubber. This method can accurately analyze the ratio of cis-butadiene rubber and styrene-butadiene rubber, improving the accuracy and efficiency of rubber formulation analysis.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for determining the ratio of cis-butadiene rubber and styrene-butadiene rubber in rubber, the method comprising the following steps:

[0007] S1. Sample preparation: Select the tire rubber sample to be tested, dry it and grind it into powder and sieve it. Take an appropriate amount of powder sample and place it in the nuclear magnetic resonance sample tube, and ensure that the sample is evenly distributed in the sample tube.

[0008] S2. Solid-state nuclear magnetic resonance testing: The sample is tested using a solid-state nuclear magnetic resonance spectrometer;

[0009] S3. Data Analysis: The acquired spectra are processed and analyzed. By analyzing the positions and areas of different peaks of carbon components of different functional groups on the spectrum, cis-butadiene rubber and styrene-butadiene rubber can be accurately distinguished.

[0010] S4. Calculate the ratio of cis to trans content in styrene-butadiene rubber: Based on the characteristic that the ratio of cis to trans content of the two closest to styrene and vinyl groups in styrene-butadiene rubber is equal to the ratio of the total cis to trans content in styrene-butadiene rubber, calculate this ratio w to further confirm the proportion of styrene-butadiene rubber. Then, calculate the proportion of cis-butadiene rubber by using the proportion of cis-butadiene in styrene-butadiene rubber and cis-butadiene in styrene-butadiene rubber.

[0011] The carbon atoms of 1,4-butadiene in styrene-butadiene rubber exhibit six vibrational frequencies in solid-state NMR, with cis-1,4-butadiene and trans-1,4-butadiene each having three. The three vibrational frequencies of cis-1,4-butadiene are: those where the carbon atom's adjacent unit is butadiene; those where the carbon atom's adjacent unit is styrene; and those where the carbon atom's adjacent unit is vinyl. Similarly, the three vibrational frequencies of trans-1,4-butadiene are: those where the carbon atom's adjacent unit is butadiene; those where the carbon atom's adjacent unit is styrene; and those where the carbon atom's adjacent unit is vinyl.

[0012] Cis-butadiene rubber is simply polymerized from 1,4-butadiene. Its carbon atom's adjacent unit is only butadiene, resulting in only one vibrational frequency in solid-state NMR, the same as the vibrational frequency of the carbon atom in styrene-butadiene rubber (SBR). The carbon atom adjacent unit being cis-butadiene comprises two parts: one part from SBR and the other from cis-butadiene rubber.

[0013] Preferably, the calculation method in S4 is as follows:

[0014] 1) In styrene-butadiene rubber, cis-1,4-butadiene and trans-1,4-butadiene each have three vibrational frequencies;

[0015] In cis-1,4-butadiene, the proportion of carbon atom adjacent units that are butadiene is denoted as a1, the proportion of carbon atom adjacent units that are styrene is denoted as b, and the proportion of carbon atom adjacent units that are vinyl is denoted as c.

[0016] In trans-1,4-butadiene, the proportion of carbon atom adjacent units that are butadiene is denoted as d, the proportion of carbon atom adjacent units that are styrene is denoted as e, and the proportion of carbon atom adjacent units that are vinyl is denoted as f.

[0017] 2) Cis-butadiene rubber is polymerized from 1,4-butadiene and has only one vibrational frequency, that is, the proportion of carbon atoms adjacent to butadiene units is denoted as a2;

[0018] 3) In rubber, the proportion of carbon atoms adjacent to butadiene units is denoted as a, i.e., a = a1 + a2;

[0019] 4) a, b, c, d, e, and f can be directly obtained through solid-state nuclear magnetic resonance, and the ratio w of the total cis and trans content in the rubber can be calculated, i.e., w = (b + c) / (e + f). Then, the butadiene content a1 in styrene-butadiene rubber is d × w, and the butadiene content a2 in cis-butadiene rubber is a - a1.

[0020] As a preferred method, the solid-state nuclear magnetic resonance test conditions are: magnetic field strength of 9.4T, resonance frequency of 400MHz, pulse repetition time of 5s, and cumulative scan count of 1024.

[0021] Furthermore, the present invention also provides the application of the method for determining the ratio of cis-butadiene rubber and styrene-butadiene rubber in rubber in tire rubber.

[0022] The beneficial effects of this invention are as follows:

[0023] 1. Improved accuracy: This invention utilizes the fundamental theory that the ratio of cis to trans content of the two compounds closest to styrene and vinyl groups in styrene-butadiene rubber is equal to the ratio of the total cis to trans content in styrene-butadiene rubber. This enables precise analysis of the ratio of cis-butadiene rubber and styrene-butadiene rubber, effectively solving the problem that existing technologies cannot accurately distinguish between these two types of rubber, and improving the accuracy and efficiency of the analysis.

[0024] 2. Expanded Scope of Application: This invention has broad applicability. It is not only applicable to the analysis of the ratio of cis-butadiene rubber and styrene-butadiene rubber in tire rubber formulations, but can also be extended to the component analysis of other polymer materials containing similar structures.

[0025] 3. Simple analysis process: This invention is more convenient and economical in practical applications, and the analysis process is simpler compared to existing solid-state NMR technology.

[0026] 4. High commercial value: The analytical method provided by this invention has significant commercial value for the tire manufacturing industry and raw material suppliers. Attached Figure Description

[0027] Figure 1This is the solid-state nuclear magnetic resonance spectrum of Example 1. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present invention.

[0029] Example 1

[0030] In this embodiment, the ratio of cis-butadiene rubber and styrene-butadiene rubber in the tread rubber was determined by solid-state nuclear magnetic resonance.

[0031] S1. Sample preparation: Select the tire rubber sample to be tested, dry it and grind it into powder and sieve it. Take an appropriate amount of powder sample and place it in the nuclear magnetic resonance sample tube, and ensure that the sample is evenly distributed in the sample tube.

[0032] S2. Solid-state nuclear magnetic resonance test: The sample was tested using a solid-state nuclear magnetic resonance spectrometer. The test conditions were: magnetic field strength of 9.4T, resonance frequency of 400MHz, pulse repetition time of 5s, and cumulative number of scans of 1024.

[0033] S3. Data Analysis: Professional nuclear magnetic resonance data processing software is used to process and analyze the acquired spectra. By analyzing the position and area of ​​different peaks of carbon components of different functional groups on the spectrum, cis-butadiene rubber and styrene-butadiene rubber can be accurately distinguished.

[0034] S4. Calculate the ratio of cis to trans content in styrene-butadiene rubber:

[0035] 1) In styrene-butadiene rubber, cis-1,4-butadiene and trans-1,4-butadiene each have three vibrational frequencies;

[0036] In cis-1,4-butadiene, the proportion of carbon atom adjacent units that are butadiene is denoted as a1; the proportion of carbon atom adjacent units that are styrene is denoted as b, where b = 6%; and the proportion of carbon atom adjacent units that are vinyl is denoted as c, where c = 10.36%.

[0037] In trans-1,4-butadiene, the proportion of carbon atom adjacent units that are butadiene is denoted as d, where d = 14%; the proportion of carbon atom adjacent units that are styrene is denoted as e, where e = 6%; and the proportion of carbon atom adjacent units that are vinyl is denoted as f, where f = 21.64%.

[0038] 2) Cis-butadiene rubber is polymerized from 1,4-butadiene and has only one vibrational frequency, that is, the proportion of carbon atoms adjacent to butadiene units is denoted as a2;

[0039] 3) In rubber, the proportion of carbon atoms adjacent to butadiene units is denoted as a, i.e., a = a1 + a2 = 14%;

[0040] 4) a, b, c, d, e, and f can be directly obtained through solid-state nuclear magnetic resonance. The ratio w of the total cis and trans content in the rubber can be calculated, i.e., w = (b+c) / (e+f) = 0.59. Then, the butadiene content in styrene-butadiene rubber a1 = d × w = 8.28%, and the butadiene content in cis-butadiene rubber a2 = a - a1 = 5.72%.

[0041] The foregoing description of embodiments of the present invention, through which those skilled in the art are able to implement or use the present invention, will be readily apparent to those skilled in the art. Various modifications to these embodiments will be readily apparent to those skilled in the art. The general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novelty disclosed herein.

Claims

1. A method for determining the ratio of cis-butadiene rubber and styrene-butadiene rubber in rubber, characterized in that, The method includes the following steps: S1. Sample preparation: Select the tire rubber sample to be tested, dry it and grind it into powder and sieve it. Take an appropriate amount of powder sample and place it in the nuclear magnetic resonance sample tube, and ensure that the sample is evenly distributed in the sample tube. S2. Solid-state nuclear magnetic resonance testing: The sample is tested using a solid-state nuclear magnetic resonance spectrometer; S3. Data Analysis: The acquired spectra are processed and analyzed. By analyzing the positions and areas of different peaks of carbon components of different functional groups on the spectrum, cis-butadiene rubber and styrene-butadiene rubber can be accurately distinguished. S4. Calculate the ratio of cis to trans content in styrene-butadiene rubber: Based on the characteristic that the ratio of cis to trans content of the two closest to styrene and vinyl groups in styrene-butadiene rubber is equal to the ratio of the total cis to trans content in styrene-butadiene rubber, calculate this ratio w to further confirm the proportion of styrene-butadiene rubber. Then, calculate the proportion of cis-butadiene rubber by using the proportion of cis-butadiene in styrene-butadiene rubber and cis-butadiene in styrene-butadiene rubber.

2. The method according to claim 1, characterized in that, The calculation method in S4 is as follows: 1) In styrene-butadiene rubber, cis-1,4-butadiene and trans-1,4-butadiene each have three vibrational frequencies; In cis-1,4-butadiene, the proportion of carbon atom adjacent units that are butadiene is denoted as a1, the proportion of carbon atom adjacent units that are styrene is denoted as b, and the proportion of carbon atom adjacent units that are vinyl is denoted as c. In trans-1,4-butadiene, the proportion of carbon atom adjacent units that are butadiene is denoted as d, the proportion of carbon atom adjacent units that are styrene is denoted as e, and the proportion of carbon atom adjacent units that are vinyl is denoted as f. 2) Cis-butadiene rubber is polymerized from 1,4-butadiene and has only one vibrational frequency, that is, the proportion of carbon atoms adjacent to butadiene units is denoted as a2; 3) In rubber, the proportion of carbon atoms adjacent to butadiene units is denoted as a, i.e., a = a1 + a2; 4) a, b, c, d, e, and f can be directly obtained through solid-state nuclear magnetic resonance, and the ratio w of the total cis and trans content in the rubber can be calculated, i.e., w = (b + c) / (e + f). Then, the butadiene content a1 in styrene-butadiene rubber is d × w, and the butadiene content a2 in cis-butadiene rubber is a - a1.

3. The method according to claim 1, characterized in that, The solid-state nuclear magnetic resonance test conditions were: magnetic field strength of 9.4T, resonance frequency of 400MHz, pulse repetition time of 5s, and cumulative scan count of 1024.

4. The application of the method according to any one of claims 1-3 in tire rubber.

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