CN-121991351-A - Liquid polysulfide rubber, and preparation method and application thereof

Abstract

The invention provides liquid polysulfide rubber, and a preparation method and application thereof. The preparation method of the polysulfide rubber comprises the steps of (1) preparing polysulfide polymer, (2) cracking the polysulfide polymer obtained in the step (1) to obtain a cracking product, (3) acidizing an organic solution containing the cracking product to obtain the liquid polysulfide rubber, and in the step (3), at least one or a mixture of two or more of benzene, toluene, xylene and ethylbenzene is selected as a solvent in the organic solution. According to the invention, the organic solvent is added into the pyrolysis product, and the organic solution of the pyrolysis product is prepared and then subjected to acidification treatment, so that the operation is simplified, the chromaticity of the product is reduced, the product quality is improved, and the pyrolysis product has excellent oil resistance, ozone resistance and low-temperature performance and has a wider application range.

Inventors

• HAN KAI

Assignees

• 北京诺维新材科技有限公司

Dates

Publication Date

20260508

Application Date

20241030

Claims (9)

1. 1.A method for preparing polysulfide rubber, characterized in that the method comprises: (1) Preparing a polysulfide polymer; (2) Cracking the polysulfide polymer obtained in the step (1) to obtain a cracking product; (3) Acidifying the organic solution containing the cracking product to obtain the liquid polysulfide rubber; The method is characterized in that in the step (3), the solvent in the organic solution is selected from at least one of benzene, toluene, xylene and ethylbenzene or a mixture of two or more of benzene, toluene, xylene and ethylbenzene.
2. 2. The preparation method of the polysulfide rubber according to claim 1, wherein the acidification treatment in the step (3) specifically comprises the steps of adding acid into an organic solution to adjust the pH to 2-3, and further washing with water to be neutral to obtain the organic solution of the polysulfide rubber. Preferably, the acid comprises an organic acid and/or an inorganic acid.
3. 3. The method according to claim 2, further comprising removing the solvent from the organic solution of polysulfide rubber.
4. 4. The process according to claim 1, wherein in step (2), the number average molecular weight of the cleavage product is 500 to 8000. Preferably, the cleavage product is a small molecule polysulfide polymer, the small molecule polysulfide polymer having sodium sulfide and/or mercapto groups as end groups.
5. 5. Liquid polysulfide rubber, characterized in that it is obtained by the preparation process according to any one of claims 1 to 4.
6. 6. The liquid polysulfide rubber of claim 6, wherein the liquid polysulfide rubber has a number average molecular weight of 500 to 7500.
7. 7. The liquid polysulfide rubber of claim 6 or 7, wherein the color value of the liquid polysulfide rubber is no greater than 10.
8. 8. The liquid polysulfide rubber of claim 7, wherein the liquid polysulfide rubber has a color value of 1 to 5.
9. 9. Use of the liquid polysulfide rubber of any of claims 5-8 in the field of aircraft oil phase sealants, adhesives for rocket propellants, construction, automobiles, railways, hollow glass, marine applications.

Description

Liquid polysulfide rubber, and preparation method and application thereof Technical Field The invention belongs to the technical field of rubber, and relates to liquid polysulfide rubber and a preparation method and application thereof. Background The liquid polysulfide rubber is easy to glue, and the product after vulcanization and solidification has excellent oil resistance, ozone resistance and low temperature performance, so that the liquid polysulfide rubber is widely applied to the fields of aircraft oil phase sealants, adhesives of rocket propellants, buildings, automobiles, railways, hollow glass, ships and the like. The production method of the liquid polysulfide rubber comprises the steps of carrying out polycondensation reaction on a sodium polysulfide aqueous solution and a dichloro monomer in a water phase with a dispersing agent to obtain polysulfide polymer emulsion, washing the emulsion for 3-4 times, removing excessive inorganic salts such as sodium polysulfide and the like until the washed latex is neutral, reacting the washed polysulfide polymer with sodium hydrosulfide and sodium sulfite to obtain a cracking product, and acidifying the cracking product to obtain the liquid polysulfide rubber. In the existing industrial production method, the cracking product is aqueous emulsion, and after the cracking product is contacted with acid, the pH is converted into a sulfhydryl-terminated polymer at 4-5, and the polymer in the aqueous emulsion is suspended in water as solid particles, so that the requirements on acidification are high, the operation is improper, and the acidification is easy to be incomplete. To solve this problem, there is a process of stepwise acidification, which is performed in three steps of ph=7, 5, 4. Even so, the acidification process still has the problems of high viscosity, incomplete acidification, difficult washing and the like of polysulfide rubber. Disclosure of Invention In order to solve the technical problems, the invention provides the following technical scheme: A method of preparing polysulfide rubber, the method comprising: (1) Preparing a polysulfide polymer; (2) Cracking the polysulfide polymer obtained in the step (1) to obtain a cracking product; (3) And (3) acidizing the organic solution containing the cracking product to obtain the liquid polysulfide rubber. According to an embodiment of the invention, the step (1) specifically comprises the step of carrying out polycondensation reaction on a sodium polysulfide solution, a dichloro monomer, alkali and a dispersing agent to obtain a polysulfide polymer emulsion. Preferably, the polysulfide polymer emulsion is water-washed to neutrality. According to an embodiment of the invention, the washing may be carried out by methods known in the art, for example, 3 times repeated with water, the pH of the emulsion after 3 times washing with water being 11, 9.5 and 8.0, respectively. According to an embodiment of the present invention, the sodium polysulfide solution is prepared by reacting sodium sulfide and sulfur according to a conventional method. According to an embodiment of the invention, the sodium polysulfide solution has a sulfur index of 1 to 5, for example 2.0. According to an embodiment of the invention, the sodium polysulfide solution has a mass fraction of sodium polysulfide of 1-50wt%, for example 10wt%, 20wt%, 30wt%, 40wt%. According to an embodiment of the invention, the structure of the dichloro monomer is Cl-R-Cl, R being selected from alkylene (for example C1-C5 alkylene), -R 11-O-R12 -, or-R 2-O-R3-O-R2 -; Wherein R 11 and R 12 are the same or different and are independently selected from C1-C5 alkylene (e.g., methylene, ethylene, propylene); R 2 and R 3 are identical or different and are selected independently of one another from C1-C5-alkylene (e.g.methylene, ethylene). Illustratively, the dichloro monomer is dichloroethyl formal, or bis (2-chloroethoxy) methane. Specifically, the dichloroethylformal can be prepared from chloroethanol and paraformaldehyde according to known methods. According to an embodiment of the present invention, the dispersant is selected from at least one of sulfonate anionic surfactants such as alkylbenzenesulfonate, alkylnaphthalene sulfonate, alkyl succinate sulfonate, alkyl diphenyl ether sulfonate, naphthalene sulfonic acid formaldehyde condensate, etc., for example, at least one of dibutylnaphthalene sulfonate, sodium butylnaphthalene sulfonate, sodium diisopropylnaphthalene sulfonate, etc. According to an embodiment of the present invention, the base is selected from at least one of inorganic bases such as sodium hydroxide, potassium hydroxide, lithium hydroxide, potassium carbonate, sodium carbonate, and the like. According to an embodiment of the invention, the polycondensation reaction comprises mixing sodium polysulfide solution, alkali and dispersant, heating to no more than 60 ℃, followed by adding an aqueous solution of a water-soluble magnesium salt, he