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CN-122011828-A - Polyamide toughening agent containing dynamic disulfide bonds, preparation method and self-repairing powder coating composition

CN122011828ACN 122011828 ACN122011828 ACN 122011828ACN-122011828-A

Abstract

The invention provides a polyamide toughening agent containing dynamic disulfide bonds, a preparation method and a self-repairing powder coating composition. The polyamide toughening agent containing dynamic disulfide bonds is of an organic-inorganic composite structure, the organic structure comprises a polyamide main body, the polyamide main body is formed by polycondensation reaction of at least one binary aliphatic diacid, at least one binary aliphatic diamine and cystamine, the polyamide toughening agent containing dynamic disulfide bonds can form a stable dispersed toughness phase in a powder coating system, effectively absorb and disperse external stress, so that a coating is not cracked under a 180-DEG bending condition, the impact resistance and flexibility of the coating are obviously improved, after scratches or microcracks are generated on the surface of the coating, the disulfide bonds can be subjected to molecular rearrangement and reconstruction under a mild heat treatment condition of about 60 ℃, the damaged area can be spontaneously healed, the scratches are obviously disappeared within 30 minutes, and the repair efficiency can reach more than 85%.

Inventors

  • XU JUNJIE
  • CAO WANGYANG
  • YU JIEBING

Assignees

  • 黄山佳杰新材料科技有限公司

Dates

Publication Date
20260512
Application Date
20260319

Claims (10)

  1. 1. A polyamide toughening agent containing dynamic disulfide bonds is characterized by being of an organic structure-inorganic composite structure, wherein the organic structure comprises a polyamide main body formed by polycondensation reaction of at least one binary aliphatic diacid, at least one binary aliphatic diamine and cystamine.
  2. 2. The dynamic disulfide bond containing polyamide toughener of claim 1, wherein the dibasic aliphatic diacid is selected from one or more of adipic acid, azelaic acid, sebacic acid, cyclohexanedicarboxylic acid, 2-methyl adipic acid, diglycolic acid, dithiodiacetic acid, or dodecanedioic acid.
  3. 3. The dynamic disulfide bond containing polyamide toughener of claim 1, wherein the dibasic aliphatic diacid is a mixed dibasic aliphatic diacid of adipic acid, sebacic acid, and cyclohexanedicarboxylic acid.
  4. 4. The dynamic disulfide bond containing polyamide toughener of claim 1, wherein the dibasic aliphatic diacid is a mixed dibasic aliphatic diacid of adipic acid, sebacic acid, and cyclohexanedicarboxylic acid in a molar ratio of 6-8:2-4:1.
  5. 5. The dynamic disulfide bond containing polyamide toughener of claim 1, wherein the dibasic aliphatic diamine is selected from one or more of 1, 6-hexamethylenediamine, 1, 8-octanediamine, 1, 10-decanediamine, in combination.
  6. 6. The dynamic disulfide bond containing polyamide toughener of claim 1, wherein the molar ratio of the dibasic aliphatic diamine to cystamine added is 80-95:5-20.
  7. 7. The method of preparing a dynamic disulfide bond containing polyamide toughener according to any one of claims 1-6, comprising the steps of: (1) Dispersing dry SiO 2 in a solvent, adding KH-550, heating and refluxing for reaction, and then centrifuging, washing and drying to obtain modified SiO 2 ; (2) Dispersing the modified SiO 2 in a solvent, adding the binary aliphatic diacid, heating and stirring uniformly; (3) Adding a mixture of binary aliphatic diamine and cystamine, and heating to perform polycondensation reaction; (4) Dewatering under vacuum, cooling, adding a large amount of deionized water for precipitation, washing, filtering, drying, and performing heat treatment to obtain the polyamide toughening agent containing dynamic disulfide bonds.
  8. 8. The method for preparing a polyamide toughening agent containing dynamic disulfide bonds according to claim 6, wherein the addition amount of KH-550 is 5-10 wt% of dry SiO 2 .
  9. 9. The method for producing a dynamic disulfide bond-containing polyamide toughener according to claim 6, wherein the heating temperature for heating and refluxing in the step (1) is 70-90 ℃, the refluxing time is 4-6 hours, the heating temperature for heating and stirring in the step (2) is 70-90 ℃, and the reaction temperature for polycondensation in the step (3) is 140-160 ℃ and the reaction time is 4-6 hours.
  10. 10. A self-healing powder coating composition comprising the dynamic disulfide bond containing polyamide toughener of any one of claims 1-6.

Description

Polyamide toughening agent containing dynamic disulfide bonds, preparation method and self-repairing powder coating composition Technical Field The invention relates to the technical field of self-repairing coating, in particular to a polyamide toughening agent containing dynamic disulfide bonds, a preparation method and a self-repairing powder coating composition. Background The powder coating is widely applied to the fields of household appliances, building materials, automobile parts, industrial protection and the like because of the advantages of no or basically no organic solvent, high utilization rate, high construction efficiency, environmental friendliness and the like. Along with the continuous expansion of the application scene of the powder coating, higher requirements are put on the comprehensive performance of the coating under the complex service condition, especially on the aspects of impact resistance, flexibility and mechanical damage resistance. However, existing powder coating systems often employ thermosetting resins (such as epoxy resins, polyester resins, or mixtures thereof) of high crosslink density, which, while achieving higher hardness and chemical resistance, generally suffer from insufficient toughness, susceptibility to microcracking, and irrecoverability after scratching. In order to improve the impact resistance and bending property of the powder coating, rubber toughening agents, thermoplastic resin toughening agents or inorganic fillers and the like are generally introduced in the prior art. The rubber toughening agent can improve the impact strength of the coating to a certain extent, but easily causes the reduction of the hardness, heat resistance and solvent resistance of the coating, and has the problems of phase separation, migration and the like in the high-temperature curing or long-term service process, the thermoplastic resin toughening agent can improve the extensibility and simultaneously has adverse effects on the leveling property, the gloss and the construction stability of the powder coating, the inorganic filler mainly plays a role in reinforcing, and has limited capability of inhibiting crack expansion, so that the problem of failure of the coating after mechanical damage is difficult to fundamentally solve. On the other hand, for repairing scratches or microcracks on the surface of a coating, the existing self-repairing technology is mostly focused on the field of solvent-type or water-based paint, for example, local repairing is realized by releasing repairing agents from microcapsules or introducing reversible physical effects. However, the technical scheme is difficult to directly apply in a powder coating system, and is difficult to stably exist due to the fact that the powder coating needs to undergo high-temperature melting and curing processes, the microcapsule structure is easy to damage, and meanwhile, the existing self-repairing system based on physical action is limited in repairing efficiency, the repairing process is not repeatable, and the requirement of industrial application on durability is difficult to meet. In addition, powder coatings inevitably produce scrap and reclaimed powder during production and construction. The existing high-crosslinking thermosetting powder coating system is irreversible in molecular structure, and the recycled powder can only be used as low-value filler, so that the material waste and the cost rise are caused. Therefore, how to realize the repeatability and the efficient utilization of resources of the powder coating system without obviously reducing the mechanical property and the heat resistance of the coating is also a technical problem to be solved in the field. In summary, the existing powder coating toughening technology generally has the defects that the toughening and mechanical properties are difficult to be compatible, the coating cannot be self-repaired after being damaged, the repairing efficiency is low and can not be repeated, the leftover materials are difficult to recycle, and the like. Therefore, the powder coating toughening agent with excellent toughening effect, self-repairing capability and repeatable processing characteristics is developed, and the stable application of the powder coating toughening agent in a powder coating system is realized, so that the powder coating toughening agent has important practical significance for improving the service reliability and the resource utilization efficiency of the powder coating. Disclosure of Invention The invention aims to provide a polyamide toughening agent containing dynamic disulfide bonds, a preparation method thereof and a self-repairing powder coating composition, wherein the dynamic covalent disulfide bonds are introduced into a polyamide molecular structure, so that the toughening agent not only can remarkably improve the flexibility and impact resistance of a coating in a powder coating system, but also can realize self-repairing und