Ziplock plastic bag is a kind of packaging product that has been used by people for many years. It is widely used for packaging medicine, food and other small bulk items. The self-sealing plastic bag uses a female button to realize the self-sealing function; the child button and the female button are arranged symmetrically and oppositely on the inner side of the plastic bag, and the length of the child button and the female button are equal, and the shapes and sizes match. The sub button is a straight plastic strip with a symmetrical arrow-shaped cross section, and the female button is a straight plastic strip with a semicircular cross section and inwardly bent claws at both ends of the semicircle. When the sub buckle is pressed into the female buckle with a slight force, the two wings of the arrow-shaped part of the sub buckle are respectively clamped on the two claw hooks of the female buckle, thereby closing the plastic bag mouth; when the plastic bag mouth is pulled slightly harder, The two arrow-shaped wings of the sub-buckle can be disengaged from the corresponding two claws of the female buckle, thereby opening the mouth of the plastic bag for taking out or loading articles. Plastic bags with this structure are usually made of polyethylene. The main disadvantages of polyethylene are poor transparency, poor high-temperature performance, poor strength, poor heat sealability, and poor printability. Therefore, people have been looking for a material with better performance. To replace polyethylene to produce self-sealing plastic bags.

Polypropylene material whose transparency, high temperature performance, mechanical strength, heat sealability and printability are better than polyethylene should be an ideal substitute material, but ziplock bags made of polypropylene have the following problems

1. The child buckle is difficult to insert into the female buckle, making the bag mouth difficult to self-seal;

2. Even if you use force to insert the sub-buckle into the female buckle, it is difficult to separate the two. Sometimes even the plastic bag cannot be opened even if the plastic bag is torn.

After analysis, it is found that the existing sealing structure of polyethylene bags is not suitable for polypropylene materials.

In addition, the polypropylene ziplock bag formed by the blow molding machine is white and opaque, and because it is brittle and lacks toughness, the technical field is looking forward to providing 1. A ziplock plastic bag made of polypropylene material; 2 . A polypropylene plastic bag with the mouth closed and open freely; 3. The production method of the above-mentioned polypropylene self-sealing plastic bag.

The present invention provides a ziplock plastic bag, which is characterized in that the ziplock plastic bag is made of polypropylene; the inside of the mouth of the ziplock plastic bag is symmetrically and oppositely provided with a snap button and a female button. The self-sealing structure; the cross section of the sub buckle is an asymmetrical arrow shape; the cross section of the female buckle is a semi-elliptical ring, and its two ends have the same width as the semi-elliptical ring and extend downward and Inwardly bent claw hooks; the shape and size of the cross section of the sub-buckle match the shape and size of the cross-section of the female buckle.