A method for preparing size-controllable high-crystallinity flaky silver powder

Nanosilver seeds were prepared by using PVP K30 and trisodium citrate, and PVA was used to control the growth direction of silver seeds, and the reduction reaction was carried out in the mixed solution of ascorbic acid and nitric acid, which was difficult to obtain both high crystallinity and high dispersion in the prior art, and high performance sheet silver powder sintered at a lower temperature was achieved.

CN119237726BActive Publication Date: 2025-03-25ZHU HAI JING RUI DIAN ZI CAI LIAO KE JI YOU XIAN GONG SI
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Patent Information

Application Number
CN202411324407.X
Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Filing Date
2024-09-23
Publication Date
2025-03-25
Estimated Expiration
2044-09-23

AI Technical Summary

Technical Problem

The prior art is difficult to achieve sheet silver powder with high crystallinity and high dispersion at the same time, and the existing methods have high reaction temperature and long reaction time, and the product aggregation is severe, which cannot meet the needs of modern applications.

Method used

Polyvinylpyrrolidone (PVP K30) is used as a dispersant, and nanosilver seeds are prepared by reducing silver nitrate by trisodium citrate. Polyvinyl alcohol (PVA) is used as a capping agent to control the growth direction of silver seeds. Finally, the reduction reaction is carried out in the mixture of ascorbic acid and nitric acid, and the pH value and crystallization direction are adjusted to prepare the silver powder with high crystallinity controllable size.

Benefits of technology

A high crystallinity sheet silver powder sintered at a lower temperature is realized, and a conductive film with high specific surface area, excellent printing and low resistance value is achieved, meeting the performance requirements of modern electronic components for conductive silver paste.

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Abstract

A method for preparing a flaky silver powder with controllable single crystal structure size comprises the following steps: first preparing a silver nitrate aqueous solution, then adding a dispersant polyvinyl pyrrolidone aqueous solution and stirring evenly, then adding a trisodium citrate aqueous solution to react and prepare a nano silver seed; finally adding a polyvinyl alcohol aqueous solution as a capping agent to the above solution, coating PVA on the {100} crystal surface of the nano silver seed by a grinding and dispersing machine, and forming a mixed solution containing silver nitrate, polyvinyl pyrrolidone, and nano silver seed coated with PVA; then preparing a nitric acid and ascorbic acid aqueous solution and mixing them into a reactor, adding the above mixed solution containing silver nitrate, polyvinyl pyrrolidone, and nano silver seed coated with PVA under stirring conditions, and mixing to cause a reduction reaction. The reduction reaction speed is controlled by adjusting the pH value of nitric acid, the growth direction of the nano silver seed is controlled by PVA, and the particle size growth size is controlled by polyvinyl pyrrolidone, and finally a flaky silver powder with controllable single crystal structure size is obtained.
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