Heat Resistant
Heatproof
noun, の adjective
If something is resistant to heat then it is heat resistant or heatproof.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
友達が耐熱容器の漫画を書いてるんだけど、主人公の容器の「耐熱容器としての限界を感じた」っていう台詞が気に入ってるのよね。
My friend is writing a manga about heat-resistant containers. The protagonist container said, "I’ve reached my limit as a heat-resistant container." I really like that line.