Cardboard is a kind of thick paper between paper and cardboard, and its weight per square meter exceeds 120g. It is used for postcards, cards, album liners and so on. The paper is fine and smooth, strong and wear-resistant.
Cardboard is divided into blue-white single-sided copper card and white-gray bottom copper card. Blue and white double-sided coated paper is obtained by full chemical bleaching, which is divided into western coated paper and copper sika. West cardboard is mainly used to make wedding invitations and other cards, while copper sika is used to make magazine covers and tags.
White coated paper is often used to make high-grade cartons because of its high whiteness. Gray coated paper is often used for beautifully packaged books.