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CN-122011240-A - Mixed regulation type chloroprene rubber and synthesis process thereof

CN122011240ACN 122011240 ACN122011240 ACN 122011240ACN-122011240-A

Abstract

The invention provides application of sulfur and alkyl mercaptan as a composite regulator in chloroprene monomer preparation of chloroprene rubber, wherein the alkyl mercaptan comprises n-dodecyl mercaptan and/or tert-dodecyl mercaptan, and the mass ratio of the sulfur to the alkyl mercaptan is (3-5): 1. The invention also provides a mixed regulation type chloroprene rubber synthesis process with cooperative regulation of sulfur and mercaptan and no need of chain breakage. The composite regulator system designed by the invention not only maintains the improvement of the processability of sulfur, but also controls the PDI by inhibiting branching through mercaptan, and does not need a chain breaking process. The synthesis method provided by the invention gives consideration to the controllable Mooney viscosity, the uniformity of molecular weight and the stability, and obtains the mixed regulation type neoprene with narrow molecular weight distribution, controllable chain breakage and long storage period.

Inventors

  • WANG XIAOFEI
  • Che Wenfu
  • WEN XUEFENG

Assignees

  • 重庆瑞淼工程技术咨询有限公司

Dates

Publication Date
20260512
Application Date
20260305

Claims (10)

  1. 1. The application of sulfur and alkyl mercaptan as composite regulator in preparing chloroprene rubber with chloroprene monomer; the alkyl mercaptans include n-dodecyl mercaptan and/or tert-dodecyl mercaptan; the mass ratio of the sulfur to the alkyl mercaptan is (3-5) 1.
  2. 2. Use according to claim 1, wherein the neoprene is in particular neoprene raw rubber; the mass ratio of the composite regulator to the chloroprene monomer is (0.12-0.45): 1; such applications include applications to enhance processability of neoprene and to inhibit branching of neoprene.
  3. 3. The use according to claim 2, wherein the means of preparation comprises a seed emulsion polymerization process; The seed emulsion is chloroprene-methyl methacrylate copolymer emulsion and/or chloroprene-methacrylic acid copolymer emulsion; such applications include narrowing the molecular weight distribution of neoprene.
  4. 4. The use of claim 1, wherein the neoprene has a PDI of 1.8 to 2.2; In the preparation process, a chain scission agent is not used; the application also includes applications in improving the mooney viscosity controllability of neoprene.
  5. 5. The mixed regulation type neoprene is characterized by comprising the following raw materials in parts by weight: 100 parts by weight of chloroprene monomer; 10-15 parts by weight of seed emulsion; 0.12-0.45 parts by weight of sulfur and alkyl mercaptan compound regulator; 0.3-0.8 parts by weight of an emulsifier; 0.3-0.5 parts of dispersing agent; 0.08-0.25 parts by weight of a redox initiation system; 3-5 parts of terminating agent; The seed emulsion is chloroprene-methyl methacrylate copolymer emulsion and/or chloroprene-methacrylic acid copolymer emulsion; the alkyl mercaptans include n-dodecyl mercaptan and/or tert-dodecyl mercaptan; in the sulfur and alkyl mercaptan compound regulator, the mass ratio of the sulfur to the alkyl mercaptan is (3-5): 1.
  6. 6. The mixed regulation neoprene of claim 5, wherein the seed emulsion has a solids content of 30% -35%; In the seed emulsion, the mass content of methyl methacrylate and/or methacrylic acid is 3% -6%; the emulsifier comprises one or more of rosin, oleic acid and sodium dodecyl benzene sulfonate, and is compounded with polyethylene glycol octyl phenyl ether; The dispersant comprises naphthalene sulfonic acid formal sodium salt and/or polyvinyl alcohol.
  7. 7. The mixed-conditioning neoprene of claim 5, wherein the redox initiation system comprises one or more oxidants of potassium persulfate, hydrogen peroxide, and cumene hydroperoxide, and one or more reductants of silver salts, thiourea dioxide, and sodium metabisulfite; In the redox initiation system, the mass ratio of the oxidant to the reducing agent is (1.5-2) 1; The initiation temperature of the redox initiation system is controlled to be 35-45 ℃; the terminator comprises one or more of phenothiazine, p-tert-butylcatechol, 2, 5-di-tert-butylhydroquinone and diethylhydroxylamine; the raw materials also comprise one or more of pH regulator, alkyl mercaptan, dispersant and coagulant.
  8. 8. A process for synthesizing the mixed-regulation neoprene according to any one of claims 5 to 7, comprising the steps of: 1) Mixing chloroprene monomer, sulfur and alkyl mercaptan compound regulator, emulsifier, dispersant and redox initiation system, and regulating pH value of the system to obtain pre-polymerized emulsion; 2) Adding seed emulsion into the pre-polymerized emulsion obtained in the step to carry out polymerization reaction, adding an alkyl mercaptan regulator, continuing polymerization, and then adding a terminator to terminate the reaction to obtain polymerized emulsion; 3) Adding an aqueous solution of acetic acid into the polymerization emulsion obtained in the above steps to demulsify, performing freeze drum coagulation, and drying to obtain the chloroprene rubber.
  9. 9. The synthesis process according to claim 8, wherein the pH is 7.5 to 9.5; The temperature of the polymerization reaction is 35-45 ℃; The condition of adding the alkyl mercaptan regulator is that the conversion rate of the polymerization reaction reaches 65% -75%; when the reaction is stopped, the conversion rate of the polymerization reaction is more than or equal to 90 percent.
  10. 10. The synthesis process according to claim 8, wherein the addition mass of the aqueous acetic acid solution is 2% -5% of the mass of the polymerization emulsion; The acetic acid aqueous solution also contains a dispersing agent with the mass content of 1% -3%; The condensing temperature of the freezing drum is-20-0 ℃; The drying temperature is 105-160 ℃.

Description

Mixed regulation type chloroprene rubber and synthesis process thereof Technical Field The invention belongs to the technical field of synthetic rubber preparation, relates to application of sulfur and alkyl mercaptan as a composite regulator in preparation of chloroprene rubber from chloroprene monomers, and relates to mixed regulation type chloroprene rubber and a synthesis process thereof, in particular to mixed regulation type chloroprene rubber and a synthesis process for cooperative regulation of sulfur and mercaptan without chain breakage. Background The Chloroprene Rubber (CR) is classified into a sulfur-regulated type (G type) and a non-sulfur-regulated type (W type) according to the type of the regulator, wherein the G type has good processing fluidity, but polysulfide bonds are easy to cause short storage period (only 3-6 months), and the Mooney viscosity has large fluctuation, and the W type has stable storage, but has high crystallinity, difficult processing and insufficient mechanical property during processing. The existing molecular weight regulator for neoprene synthesis is divided into a single regulation type CR and a mixed regulation type CR, wherein the mixed regulation type CR is cooperatively regulated by sulfur and a regulator butyl, so that the advantages of the single regulation type CR and the mixed regulation type CR can be considered, but the existing technology has the following defects: 1. The chemical formula of the regulator butyl (diisopropyl xanthogenate disulfide) is C 8H14O2S4, the regulator belongs to xanthogenate molecular weight regulators, the relative mercaptan is greatly influenced by temperature and pH value, the control on the branching degree of a molecular chain is relatively poor, the polymerization rate is possibly influenced, and a large molecular weight long chain is not easy to obtain; 2. The chain scission process has poor controllability, the traditional sulfur-regulated CR latex needs to be added with TETD for chain scission, so that 'early slow and later dip' is easy to occur, the Mooney viscosity fluctuation is large, and the Mooney viscosity of the same batch is often higher than 10-30 ML (1+4) 100 ℃; 3. The molecular weight distribution is wide, the branching reaction is difficult to control in the polymerization process, the PDI is more than 2.5, the processing uniformity is affected, and the chlorine soluble substances are more than or equal to 15ppm. WO2023/103893A1, as disclosed in the prior art, while optimizing the mixing system, does not address the problem of uncontrolled viscosity at the end of chain scission. Therefore, how to develop a more suitable mixed regulation neoprene and a synthesis process thereof, which solve the above technical problems existing in the existing mixed regulation neoprene synthesis process, has become one of the important problems to be solved by many first-line production developers and industry manufacturers in the industry. Disclosure of Invention In view of the above, the technical problem to be solved by the present invention is to provide an application of sulfur and alkyl mercaptan as a composite regulator in the preparation of chloroprene rubber from chloroprene monomers, a mixed regulation type chloroprene rubber and a synthesis process thereof. The synthesis method provided by the invention gives consideration to the controllability of the Mooney viscosity, the uniformity of the molecular weight and the stability, obtains the mixed regulation type neoprene with narrow molecular weight distribution, controllable chain breakage and long storage period, has simple process, mild conditions, good controllability and high stability, and is more suitable for popularization and application of industrial production. The invention provides an application of sulfur and alkyl mercaptan as a composite regulator in chloroprene monomer preparation of chloroprene rubber; the alkyl mercaptans include n-dodecyl mercaptan and/or tert-dodecyl mercaptan; the mass ratio of the sulfur to the alkyl mercaptan is (3-5) 1. Preferably, the neoprene is neoprene rubber; the mass ratio of the composite regulator to the chloroprene monomer is (0.12-0.45): 1; such applications include applications to enhance processability of neoprene and to inhibit branching of neoprene. Preferably, the mode of preparation comprises a seed emulsion polymerization process; The seed emulsion is chloroprene-methyl methacrylate copolymer emulsion and/or chloroprene-methacrylic acid copolymer emulsion; such applications include narrowing the molecular weight distribution of neoprene. Preferably, the PDI of the neoprene is 1.8-2.2; In the preparation process, a chain scission agent is not used; the application also includes applications in improving the mooney viscosity controllability of neoprene. The invention provides mixed regulation type chloroprene rubber, which comprises the following raw materials in parts by weight: 100 parts by weight of chloropre