What do AA, KK and TK in the carton stand for respectively?

The "=" of A=A means that five-layer corrugated board (or double corrugated board), face paper and inner paper use A paper, and corrugated and medium-thick paper use ordinary corrugated base paper.

KK is a hard carton material.

The hardness of general carton board is K>A & gtB& gt；; C.

K stands for one of the better materials in the carton, which is often called cow paper.

Then k paper also has good or bad points:

K = K & gtK = A & gtk = B& gt； K3K & gtK2A & gtK3B .

The strength decreases in turn, which is worse in K paper K3B.