Method for determining ratio of cis-butadiene rubber to butadiene styrene rubber in rubber and application

Abstract

The invention relates to the technical field of chemical analysis, and discloses a method for determining the ratio of cis-butadiene rubber to butadiene styrene rubber in rubber and application. According to the method, the percentage of each functional group is obtained based on solid nuclear magnetic resonance, and the ratio of the cis content to the trans content of styrene and vinyl in butadiene styrene rubber is equal to the total ratio of the cis content to the trans content in the butadiene styrene rubber. The proportion of cis-butadiene rubber and butadiene styrene rubber is accurately analyzed, the problem that the cis-butadiene rubber and the butadiene styrene rubber cannot be accurately distinguished in the prior art is effectively solved, and the analysis accuracy and the analysis efficiency are improved. The method has wide applicability, the analysis process is simple, convenient and rapid, and the method has important commercial value.

Description

Technical Field

[0001] The invention relates to the technical field of chemical analysis, in particular to a method for determining the ratio of cis-butadiene rubber and styrene-butadiene rubber in rubber and its application. Background Art

[0002] In the field of polymer materials, especially in tire manufacturing, the performance of tires depends largely on the rubber formula inside them. Among them, cis-butadiene rubber (BR) and styrene-butadiene rubber (SBR) are two commonly used types of rubber, which are indispensable in many tire formulations. However, the formula of these rubbers, especially the ratio between the two, is a very important trade secret and is usually not disclosed. In the field of chemical analysis technology, nuclear magnetic resonance technology (NMR) is an important analytical tool that can be used to determine the molecular structure and composition of polymer materials. By analyzing the composition of carbon in different functional groups, the proportion of rubber can be inferred. However, since both cis-butadiene rubber and styrene-butadiene rubber contain cis-butadiene monomers in their structural units, it is difficult to distinguish the two using existing technologies.

[0003] The existing solution is mainly to obtain the percentage of each functional group through solid-state nuclear magnetic resonance, and then infer the proportion of rubber in the formula. This method can provide valuable information about the rubber formula, but because of the structural similarity of cis-butadiene rubber and styrene-butadiene rubber, it cannot accurately distinguish between the two rubbers. Although solid-state nuclear magnetic resonance technology has a certain effect in analyzing rubber formulas, it has some significant limitations. The main problem is that it cannot accurately distinguish between cis-butadiene rubber and styrene-butadiene rubber. The structures of these two rubbers are very similar and both contain cis-butadiene monomers, which makes it difficult to obtain their exact proportion through existing nuclear magnetic resonance technology. In addition, since the formula may also contain other ingredients, such as fillers, additives, etc., this further increases the complexity of the analysis. Therefore, how to accurately analyze the ratio of cis-butadiene rubber and styrene-butadiene rubber in tire rubber formulas is still a problem that needs to be solved in this field. Summary of the invention

[0004] The invention aims at the deficiencies of the prior art and provides a method for determining the ratio of cis-butadiene rubber to styrene-butadiene rubber in rubber and its application. The method can accurately analyze the ratio of cis-butadiene rubber to styrene-butadiene rubber, thereby improving the accuracy and efficiency of rubber formula analysis.

[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions: A method for determining the ratio of cis-butadiene rubber to styrene-butadiene rubber in rubber, the method comprising the following steps: S1. Sample preparation: Select the tire rubber sample to be tested, dry it, grind it into powder, and sieve it. Take an appropriate amount of powder sample and put it into the NMR sample tube, and ensure that the sample is evenly distributed in the sample tube; S2, solid-state nuclear magnetic resonance test: use a solid-state nuclear magnetic resonance instrument to test the sample; S3. Data analysis: Process and analyze the acquired spectra, and accurately distinguish cis-butadiene rubber from styrene-butadiene rubber by analyzing the positions and areas of different peaks of carbon components with different functional groups on the spectra; S4. Calculate the ratio of cis content to trans content in styrene-butadiene rubber: According to the characteristic that the ratio of cis content to trans content of styrene and vinyl in styrene-butadiene rubber is equal to the ratio of total cis content to trans content in styrene-butadiene rubber, calculate this ratio w to further confirm the proportion of styrene-butadiene rubber, and then calculate the proportion of cis-butadiene rubber through the ratio of cis-butadiene rubber and cis-butadiene in styrene-butadiene rubber.

[0006] The carbon atoms of 1,4-butadiene in styrene-butadiene rubber will have 6 vibration frequencies in solid-state nuclear magnetic resonance, of which cis-1,4-butadiene and trans-1,4-butadiene have three each. The three vibration frequencies of cis-1,4-butadiene are: the adjacent carbon atom units are butadiene; the adjacent carbon atom units are styrene structures; the adjacent carbon atom units are vinyl; the three vibration frequencies of trans-1,4-butadiene are: the adjacent carbon atom units are butadiene; the adjacent carbon atom units are styrene structures; the adjacent carbon atom units are vinyl.

[0007] Cis-butadiene rubber is simply polymerized from 1,4-butadiene. Its carbon atom adjacent units are only butadiene, and it has only one vibration frequency in solid-state nuclear magnetic resonance, which is the same as the vibration frequency of the carbon of butadiene in styrene-butadiene rubber. The carbon atom adjacent units of cis-butadiene include two parts, one from styrene-butadiene rubber and the other from cis-butadiene rubber.

[0008] Preferably, 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 vibration frequencies; In cis-1,4-butadiene, the proportion of adjacent carbon atom units that are butadiene is recorded as a1, the proportion of adjacent carbon atom units that are styrene structures is recorded as b, and the proportion of adjacent carbon atom units that are vinyl structures is recorded as c; In trans-1,4-butadiene, the proportion of adjacent carbon atom units that are butadiene is recorded as d, the proportion of adjacent carbon atom units that are styrene structures is recorded as e, and the proportion of adjacent carbon atom units that are vinyl is recorded as f; 2) Cis-butadiene rubber is polymerized from 1,4-butadiene and has only one vibration frequency, that is, the proportion of adjacent carbon atom units being butadiene is recorded as a2; 3) In rubber, the proportion of adjacent carbon atom units that are butadiene is recorded as a, that is, a=a1+a2; 4) Through solid-state nuclear magnetic resonance, a, b, c, d, e, and f can be directly obtained, and the ratio w of the total cis- and trans-content in the rubber can be calculated, that is, w = (b + c) / (e + f). Therefore, the butadiene component a1 in styrene-butadiene rubber is a1 = d × w, and the butadiene component a2 in cis-butadiene rubber is a2 = a-a1.

[0009] Preferably, the solid-state nuclear magnetic resonance test conditions are: magnetic field intensity of 9.4T, resonance frequency of 400MHz, pulse repetition time of 5s, and cumulative scanning times of 1024 times.

[0010] Furthermore, the present invention also provides the application of the method for determining the ratio of cis-butadiene rubber to styrene-butadiene rubber in rubber in tire rubber.

[0011] The beneficial effects of the present invention are: 1. Improved accuracy: The present invention uses the basic theory that the ratio of the cis content to the trans content of styrene and vinyl in styrene-butadiene rubber is equal to the ratio of the total cis content to the trans content in styrene-butadiene rubber, thereby achieving accurate analysis of the ratio of cis-butadiene rubber and styrene-butadiene rubber, effectively solving the problem that the prior art cannot accurately distinguish between the two rubbers, and improving the accuracy and efficiency of the analysis.

[0012] 2. Expansion of the scope of application: The present invention has wide applicability and is not only suitable for analyzing the ratio of cis-butadiene rubber and styrene-butadiene rubber in tire rubber formulas, but can also be extended to the component analysis of other polymer materials with similar structures.

[0013] 3. Simple analysis process: The present invention is more convenient and economical in practical application, and the analysis process is simpler than the existing solid-state nuclear magnetic resonance technology.

[0014] 4. High commercial value: The analysis method provided by the present invention has important commercial value for the tire manufacturing industry and raw material suppliers. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is the solid-state nuclear magnetic resonance spectrum of Example 1. DETAILED DESCRIPTION

[0016] 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 described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] Example 1 In this embodiment, the ratio of cis-butadiene rubber to styrene-butadiene rubber in the tread rubber is determined by solid-state nuclear magnetic resonance.

[0018] S1. Sample preparation: Select the tire rubber sample to be tested, dry it, grind it into powder, and sieve it. Take an appropriate amount of powder sample and put it into the NMR sample tube, and ensure that the sample is evenly distributed in the sample tube; S2. Solid-state nuclear magnetic resonance test: The samples were tested using a solid-state nuclear magnetic resonance instrument; the test conditions were: magnetic field intensity of 9.4T, resonance frequency of 400MHz, pulse repetition time of 5s, and cumulative scanning times of 1024 times; S3. Data analysis: Use professional NMR data processing software to process and analyze the acquired spectra. By analyzing the positions and areas of different peaks of carbon components with different functional groups on the spectra, cis-butadiene rubber and styrene-butadiene rubber can be accurately distinguished. S4. Calculate the ratio of cis content to trans content in styrene-butadiene rubber: 1) In styrene-butadiene rubber, cis-1,4-butadiene and trans-1,4-butadiene each have three vibration frequencies; In cis-1,4-butadiene, the proportion of adjacent carbon atom units that are butadiene is recorded as a1; the proportion of adjacent carbon atom units that are styrene structures is recorded as b, b=6%; the proportion of adjacent carbon atom units that are vinyl is recorded as c, c=10.36%; In trans-1,4-butadiene, the proportion of adjacent carbon atom units that are butadiene is recorded as d, d=14%; the proportion of adjacent carbon atom units that are styrene structures is recorded as e, e=6%; the proportion of adjacent carbon atom units that are vinyl is recorded as f, f=21.64%; 2) Cis-butadiene rubber is polymerized from 1,4-butadiene and has only one vibration frequency, that is, the proportion of adjacent carbon atom units being butadiene is recorded as a2; 3) In rubber, the proportion of adjacent carbon atom units that are butadiene is recorded as a, that is, a=a1+a2=14%; 4) Through solid-state nuclear magnetic resonance, a, b, c, d, e, and f can be directly obtained, and the ratio w of the total cis-to-trans content in the rubber can be calculated, that is, w=(b+c) / (e+f)=0.59. The butadiene component in styrene-butadiene rubber is a1=d×w=8.28%, and the butadiene component in cis-butadiene rubber is a2=a-a1=5.72%.

[0019] The above is a description of the embodiments of the present invention. Through the above description of the disclosed embodiments, professionals and technicians in the field can implement or use the present invention. Various modifications to these embodiments will be apparent to professionals and technicians 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 these embodiments shown in this article, but will conform to the widest range consistent with the principles and novelties disclosed herein.

Claims

1. A method for determining the ratio of cis-butadiene rubber to styrene-butadiene rubber in rubber, characterized in that: The method comprises the following steps: S1. Sample preparation: Select the tire rubber sample to be tested, dry it, grind it into powder, and sieve it. Take an appropriate amount of powder sample and put it into the NMR sample tube, and ensure that the sample is evenly distributed in the sample tube; S2, solid-state nuclear magnetic resonance test: use a solid-state nuclear magnetic resonance instrument to test the sample; S3. Data analysis: Process and analyze the acquired spectra, and accurately distinguish cis-butadiene rubber from styrene-butadiene rubber by analyzing the positions and areas of different peaks of carbon components with different functional groups on the spectra; S4. Calculate the ratio of cis content to trans content in styrene-butadiene rubber: According to the characteristic that the ratio of cis content to trans content of styrene and vinyl in styrene-butadiene rubber is equal to the ratio of total cis content to trans content in styrene-butadiene rubber, calculate this ratio w to further confirm the proportion of styrene-butadiene rubber, and then calculate the proportion of cis-butadiene rubber through the ratio of cis-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 vibration frequencies; In cis-1,4-butadiene, the proportion of adjacent carbon atom units that are butadiene is recorded as a1, the proportion of adjacent carbon atom units that are styrene structures is recorded as b, and the proportion of adjacent carbon atom units that are vinyl structures is recorded as c; In trans-1,4-butadiene, the proportion of adjacent carbon atom units that are butadiene is recorded as d, the proportion of adjacent carbon atom units that are styrene structures is recorded as e, and the proportion of adjacent carbon atom units that are vinyl is recorded as f; 2) Cis-butadiene rubber is polymerized from 1,4-butadiene and has only one vibration frequency, that is, the proportion of adjacent carbon atom units being butadiene is recorded as a2; 3) In rubber, the proportion of adjacent carbon atom units that are butadiene is recorded as a, that is, a=a1+a2; 4) Through solid-state nuclear magnetic resonance, a, b, c, d, e, and f can be directly obtained, and the ratio w of the total cis- and trans-content in the rubber can be calculated, that is, w = (b + c) / (e + f). Therefore, the butadiene component a1 in styrene-butadiene rubber is a1 = d × w, and the butadiene component a2 in cis-butadiene rubber is a2 = a-a1.

3. The method according to claim 1, characterized in that The solid-state NMR test conditions are as follows: magnetic field intensity of 9.4 T, resonance frequency of 400 MHz, pulse repetition time of 5 s, and cumulative scanning times of 1024 times.

4. Use of the method according to any one of claims 1 to 3 in tire rubber.

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