POLYESTER RESIN AND CAN COATING RESIN COMPOSITION COMPRISING THE SAME

PROBLEM TO BE SOLVED: To provide a polyester resin suitable for a can coating resin composition from which such a coating film can be formed that excels in anti-contamination property on a content and in alkali resistance and substantially prevents decrease in processability with time, and a can coating resin composition.SOLUTION: A polyester resin is obtained by reacting a polycarboxylic acid (A) and a polyol (B). The polycarboxylic acid (A) in total 100 mol% comprises 15 to 50 mol% of terephthalic acids and 50 to 85 mol% of isophthalic acids. And the polyol (B) in total 100 mol% comprises 35 to 70 mol% of a linear diol (a) having 4 to 6 carbon atoms and having a primary hydroxyl group at both ends and no side chain, 10 to 45 mol% of a branched diol (b) having two primary hydroxyl groups and an alkyl group having 1 to 4 carbon atoms as a side chain, and 5 to 40 mol% of a diol (c) having 2 to 3 carbon atoms.SELECTED DRAWING: Figure 1 【課題】耐内容物汚染性および耐アルカリ性が優れ、経時後の加工性が低下し難い塗膜を形成できる缶被覆用樹脂組成物に適したポリエステル樹脂、および缶被覆用樹脂組成物を提供すること。【解決手段】ポリカルボン酸（Ａ）とポリオール（Ｂ）とを反応させてなるポリエステル樹脂であって、前記ポリカルボン酸（Ａ）の合計１００モル％中、テレフタル酸類を１５〜５０モル％、イソフタル酸類を５０〜８５モル％含み、前記ポリオール（Ｂ）の合計１００モル％中、炭素数４〜６であり、１級の水酸基を両末端にそれぞれ有し、側鎖を有しない直鎖状ジオール（ａ）を３５〜７０モル％、１級の水酸基を２個有し、側鎖として炭素数１〜４のアルキル基を有する分岐型ジオール（ｂ）を１０〜４５モル％、および炭素数２〜３のジオール（ｃ）を５〜４０モル％含むポリエステル樹脂。【選択図】図１