noun
hardener; curing agent; stiffening agent
Technical term used in chemistry, materials science, and manufacturing for a substance that causes another material to harden or cure.
エポキシ樹脂には硬化剤が必要です。
Epoxy resin requires a hardener.
この接着剤は硬化剤を混ぜると固まります。
This adhesive hardens when mixed with a curing agent.
触媒 is a catalyst that speeds up a reaction without being consumed, while 硬化剤 is a substance that directly participates in the hardening process.
Compound of 硬化 (hardening) + 剤 (agent, chemical).