Polyoxymethylene film and preparation method thereof

A method for preparing polyoxymethylene film, the polyoxymethylene film comprising:

• 96 to 98 parts by weight of polyoxymethylene resin,
• 0.5 to 2 parts by weight of nucleating agent,
• 0.5 to 1 parts by weight of antioxidant, and
• 0.5 to 1 parts by weight of formaldehyde absorbent,
• wherein the polyoxymethylene resin has a molecular formula of —(CH2—O)n—(CH2—CH2—O)—m, wherein —(CH2—CH2—O)—m are copolymerization units accounting for a molar ratio 3% to 30%,
• the method comprising the following steps:
• (1) forming a mixture by putting the above parts by weight of the polyoxymethylene, the nucleating agent, the antioxidant, and the formaldehyde absorbent into a high-speed mixer and mixing them uniformly;
• (2) forming a tube by placing the mixture into a hopper of a screw extruder, melting the mixture to obtain a molten mass, and extruding the molten mass through a die;
• (3) forming polyoxymethylene films by a blown film process, comprising stretching the tube upward and blowing compressed air into the tube to form a blown film bubble, and simultaneously cooling the blown film bubble by using a multistage air cooling ring around the outer surface of the bubble, then collapsing the cooled blown film bubble by passing through a collapsing frame and thereafter through pulling rollers, then solidifying, cutting and winding onto rolls.