阅读说明：本技术 一种天然橡胶的拆解方法 (Method for disassembling natural rubbers ) 是由 张福全 廖禄生 王兵兵 孙中锐 李高荣 汪月琼 林宏图 邓东华 彭政 于 2019-10-25 设计创作，主要内容包括：本发明提供了一种天然橡胶的拆解方法,属于天然橡胶技术领域。本发明提供的拆解方法包括如下步骤：将天然橡胶溶解于有机溶剂中,得到天然橡胶溶液；在保护气氛和避光条件下,将所述天然橡胶溶液与甲醇钠混合后进行回流反应,然后将回流反应所得反应液中和后,与甲醇混合,经冷藏,完成拆解。在本发明中,回流反应过程中,甲醇钠与天然橡胶分子链一端的端基—类脂发生酯交换反应,则产生分子交联的类脂连接点被打断；然后将回流反应所得反应液中和后,与甲醇混合,甲醇会将天然橡胶分子链与蛋白质形成的氢键打断,从而得到线性分子。(The invention provides a method for disassembling natural rubbers, which belongs to the technical field of natural rubbers and comprises the following steps of dissolving natural rubbers in an organic solvent to obtain a natural rubber solution, mixing the natural rubber solution with sodium methoxide for reflux reaction under the conditions of protective atmosphere and light protection, neutralizing reaction liquid obtained by the reflux reaction, mixing the neutralized reaction liquid with methanol, refrigerating, and disassembling.)

The method for disassembling the natural rubber of the varieties is characterized by comprising the following steps:

dissolving natural rubber in an organic solvent to obtain a natural rubber solution;

mixing the natural rubber solution with sodium methoxide under the conditions of protective atmosphere and light protection, then carrying out reflux reaction, neutralizing the reaction solution obtained by the reflux reaction, mixing with methanol, and refrigerating to finish the disassembly of the natural rubber.

2. The disassembly method of claim 1, wherein the organic solvent is toluene, tetrahydrofuran, or cyclohexane.

3. The disassembling method according to claim 1 or 2, characterized in that the organic solvent contains at least antioxidants selected from 2, 6-di-tert-butyl-4-methylphenol, tert-butylhydroquinone, antioxidant 264, antioxidant 1010 and antioxidant 1076, and the concentration of the antioxidants is 50-250 ppm.

4. The disassembling method according to claim 1 or 2, wherein the amount ratio of the natural rubber to the organic solvent is 1 to 10 mg/mL.

5. The disassembling method according to claim 1, wherein the dissolving is carried out under a dark condition, the dissolving time is 3-7 days, the shaking time is 0.5-2 hours per day, and the rotation speed of the shaking is 50-300 rpm.

6. The disassembling method according to claim 1, wherein the sodium methoxide is added in the form of a sodium methoxide solution, the mass ratio of the sodium methoxide solution to the natural rubber is 1.5 to 2:1, and the concentration of the sodium methoxide solution is 25 to 50 wt.%.

7. The disassembling method according to claim 1, wherein the temperature of the reflux reaction is 60 to 85 ℃ and the time is 2 to 8 hours.

8. The disassembling method according to claim 1, wherein after the neutralization, the reaction liquid obtained by the neutralization is concentrated and then mixed with methanol, the concentration degree is 1/20-1/5 of the volume of the reaction liquid, and the volume ratio of the concentrated liquid to the methanol is 1: 5-10.

9. The dismantling method according to claim 1, wherein the temperature of the refrigeration is 1-10 ℃ and the time is 16-24 h.

10. The dismantling method according to claim 1, wherein the temperature of the refrigeration is 2 to 10 ℃ and the time is 16 to 24 hours.

Technical Field

The invention relates to the technical field of natural rubber, in particular to a method for disassembling natural rubber.

Background

The natural rubber is polyisoprene polymerized from monomer isoprene in a rubber tree, the inherent molecule of the polyisoprene is linear, however, due to the influence of the interaction of hydrogen bonds or chemical bonds between molecular chain end groups and non-rubber substances (proteins and lipids) in the natural rubber, the molecular chain of the polyisoprene of the natural rubber is branched and crosslinked in the processes of biosynthesis, processing and storage to form a physical network structure, the physical network structure forms rubber gel, insoluble gel in a sample is filtered and removed when the molecular weight of the natural rubber is measured by adopting gel permeation chromatography, so that the test result cannot reflect the actual molecular weight of the natural rubber, and in addition, , the rubber molecule is branched and gradually increased in the processes of processing and storage, so that the shape and the position of a molecular weight distribution curve are dynamically changed, the inherent property of the polyisoprene rubber molecule cannot be embodied, and the accurate analysis and evaluation of the molecular weight of the natural rubber is influenced.

Disclosure of Invention

The invention aims to provide a method for disassembling kinds of natural rubber, which is simple to operate and can completely disassemble the natural rubber.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a method for disassembling natural rubbers, which comprises the following steps:

dissolving natural rubber in an organic solvent to obtain a natural rubber solution;

mixing the natural rubber solution with sodium methoxide under the conditions of protective atmosphere and light protection, then carrying out reflux reaction, neutralizing the reaction solution obtained by the reflux reaction, mixing with methanol, and refrigerating to finish the disassembly of the natural rubber.

Preferably, the organic solvent is toluene, tetrahydrofuran or cyclohexane.

Preferably, the organic solvent contains an antioxidant, the antioxidant is at least of 2, 6-di-tert-butyl-4-methylphenol, tert-butyl hydroquinone, an anti-aging agent 264, an antioxidant 1010 and an antioxidant 1076, and the concentration of the antioxidant is 50-250 ppm.

Preferably, the dosage ratio of the natural rubber to the organic solvent is 1-10 mg/mL.

Preferably, the dissolving is carried out under the condition of keeping out of the sun, the dissolving time is 3-7 days, the vibration is carried out for 0.5-2 hours every day, and the rotating speed of the vibration is 50-300 rpm.

Preferably, the sodium methoxide is added in the form of a sodium methoxide solution, the mass ratio of the sodium methoxide solution to the natural rubber is 1.5-2: 1, and the concentration of the sodium methoxide solution is 25-50 wt.%.

Preferably, the temperature of the reflux reaction is 60-85 ℃, and the time is 2-8 h.

Preferably, after neutralization, the reaction liquid obtained by neutralization is concentrated and then mixed with methanol, the concentration degree is 1/20-1/5 of the volume of the reaction liquid, and the volume ratio of the concentrated liquid to the methanol is 1: 5-10.

Preferably, the refrigeration temperature is 1-10 ℃, and the time is 16-24 h.

Preferably, the refrigeration temperature is 2-10 ℃ and the refrigeration time is 16-24 h.

The invention provides a method for disassembling natural rubbers, which comprises the following steps of dissolving natural rubber in an organic solvent to obtain a natural rubber solution, mixing the natural rubber solution with sodium methoxide under the conditions of protective atmosphere and light protection, carrying out reflux reaction, neutralizing the reaction solution obtained by the reflux reaction, mixing the reaction solution with methanol, and refrigerating to disassemble the natural rubber.

Drawings

FIG. 1 is a graph showing the molecular weight distribution of the natural rubber used in the example;

FIG. 2 is a graph showing the molecular weight distribution of the disassembled product obtained in example 1;

FIG. 3 is a graph showing the molecular weight distribution of the disassembled product obtained in example 2;

FIG. 4 is a graph showing the molecular weight distribution of the disassembled product obtained in example 3;

FIG. 5 is a graph showing the molecular weight distribution of the disassembled product obtained in example 1 and comparative example 1, in which the dotted line is the molecular weight distribution curve of the disassembled product obtained in example 1, and the solid line is the molecular weight distribution curve of the disassembled product obtained in comparative example 1.

Detailed Description

The invention provides a method for disassembling natural rubbers, which comprises the following steps:

dissolving natural rubber in an organic solvent to obtain a natural rubber solution;

mixing the natural rubber solution with sodium methoxide under the conditions of protective atmosphere and light protection, then carrying out reflux reaction, neutralizing the reaction solution obtained by the reflux reaction, mixing with methanol, and refrigerating to finish the disassembly of the natural rubber.

The invention dissolves natural rubber in organic solvent to obtain natural rubber solution.

In the present invention, the natural rubber is preferably 1mm or less in volume³Small pieces of (a).

In the present invention, the organic solvent is preferably toluene, tetrahydrofuran or cyclohexane. In the present invention, the above organic solvent is advantageous for sufficiently dissolving the natural rubber.

In the invention, the solvent preferably contains an antioxidant, the antioxidant is preferably at least of 2, 6-di-tert-butyl-4-methylphenol, tert-butyl hydroquinone, an anti-aging agent 264, an antioxidant 1010 and an antioxidant 1076, and the concentration of the antioxidant is preferably 50-250 ppm, more preferably 100-200 ppm.

In the invention, the dosage ratio of the natural rubber to the organic solvent is preferably 1-10 mg/mL, and more preferably 3-8 mg/mL.

In the invention, the dissolving is preferably carried out under a dark condition, the dissolving time is preferably 3-7 days, the shaking is preferably carried out for 0.5-2 hours every day, and the rotating speed of the shaking is preferably 50-300 rpm; the dissolution time is more preferably 7 days, and the shaking time per day is more preferably 1 hour. In the present invention, the above dissolution process can ensure sufficient swelling of the natural rubber; and the light-shielding condition can avoid the degradation of the molecular chain of the natural rubber.

After the natural rubber solution is obtained, the natural rubber solution and sodium methoxide are mixed and then subjected to reflux reaction under the conditions of protective atmosphere and light shielding, in the reflux reaction process, the sodium methoxide and the end group-lipoid at the end of the natural rubber molecular chain undergo ester exchange reaction, so that the lipoid connection point for generating molecular crosslinking is broken, and the light shielding condition can avoid the degradation of the natural rubber molecular chain.

In the present invention, the mass ratio of the sodium methoxide to the natural rubber is preferably 1.5 to 2: 1.

In the present invention, the sodium methoxide is preferably added in the form of a sodium methoxide solution, the solvent of which is preferably methanol, and the sodium methoxide solution is preferably a freshly prepared sodium methoxide solution; the concentration of the sodium methoxide solution is preferably 25-50 wt.%. The method for preparing the sodium methoxide solution is not particularly limited in the present invention.

The protective atmosphere is not particularly limited in the invention, and the conventional protective atmosphere such as nitrogen and argon can be adopted.

In the invention, the temperature of the reflux reaction is preferably 60-85 ℃, more preferably 65-70 ℃, and the time is preferably 2-6 hours, more preferably 3-4 hours.

After the reflux reaction is completed, the reaction solution obtained by the reflux reaction is preferably cooled to room temperature and then neutralized in the present invention.

In the present invention, the cooling is preferably natural cooling.

In the present invention, the acid solution used for the neutralization is preferably hydrochloric acid, an ether solution of hydrogen chloride or a methanol solution of hydrogen chloride, and the concentration of the acid solution is not particularly limited in the present invention.

After neutralization, the reaction solution obtained in the invention is mixed with methanol, and the natural rubber is disassembled after refrigeration. In the invention, the methanol is added and then refrigerated, and during the refrigeration process, the methanol can break the hydrogen bond formed by the natural rubber molecular chain and the protein, thereby obtaining the linear molecule.

In the invention, after neutralization, the reaction liquid obtained by neutralization is preferably concentrated and then mixed with methanol, the concentration degree is preferably 1/20-1/5 of the volume of the reaction liquid, and the volume ratio of the volume of the concentrated liquid to the volume of the methanol is preferably 1: 5-10.

In the invention, the refrigerating temperature is preferably 1-10 ℃, more preferably 2-10 ℃, most preferably 8-10 ℃, and the time is preferably 16-24 h.

After refrigeration is completed, the present invention preferably takes the resulting solids out and dries them to yield a disassembled product. In the present invention, the refrigeration enables sufficient precipitation of linear molecules.

In the present invention, the drying is preferably vacuum drying; the temperature of the vacuum drying is preferably room temperature. The vacuum drying time is not specially limited, and a product with constant weight can be obtained.

In the present invention, the obtained disassembled product can be used for measuring the inherent molecular weight of natural rubber, for studying the structure of natural rubber or for controlling the quality of natural rubber.

The method for disassembling natural rubbers according to the present invention will be described in detail with reference to the following examples, but they should not be construed as limiting the scope of the present invention.