Crystalline and easily recyclable polyester heat shrinkable film and preparation method thereof

A crystalline and easily recyclable polyester heat shrinkable film, having a three-layer porous structure of layer A/layer B/layer C, wherein the layer A is prepared by raw materials consisting of polyethylene terephthalate glycol copolymer (PETG), a functional master batch and polyethylene terephthalate (PET), the layer B is prepared by raw materials consisting of a modified PET, PET, a nucleating agent, a chain extender, and a foaming agent, the modified PET being a neopentyl glycol (NPG) modified PET;

• a mass percentage ratio of PETG, the functional batch, and PET in layer A is in a range of 89.4-66.0%:1.6-4.0%:10.0-30.0%, a mass percentage ratio of the modified PET, PET, the nucleating agent, the chain extender, and the foaming agent in layer B is in a range of 42-65.4%:30-40%:0.6-4.0%:2.0-6.0%:2.0-8.0%;
• the functional master batch consisting of at least one selected from the group consisting of silicon dioxide, talcum powder, clay and kaolin, and at least one selected from the group consisting of oleamide and erucamide;
• the nucleating agent consists of dibutyl sebacate, ammonium phosphate and sodium benzoate in a ratio of 1:1:4;
• the chain extender is glycidyl methacrylate;
• and
• the foaming agent consists of barium azodicarboxylate and p-toluenesulfonyl semicarbazide in a ratio of 1:5.