Easy-open films are mainly used in the packaging of after-dinner snacks and other related leisure foods, and are a functional packaging material that has been developed in response to the demand for ease of use. According to traditional thinking, the requirement for packaging is to be as strong as possible, believing that the stronger the packaging the better the protection of the product and therefore the more desirable it is. However, with the development of society, especially in recent years, due to the arrival of an ageing society, there is a strong objective demand for convenient opening, the previous one-sided emphasis on the protection of the packaging of goods, at the expense of the concept of openness has been greatly impacted, while a new way of thinking: the requirement for packaging, especially the packaging of convenience foods and other goods, should be able to effectively protect the contents of its packaging, but also to This has led to the development and application of easy-open functional packaging films - easy-open films. www.susumino. com
1. Classification of easy-to-open films
Industrialized easy-to-open films have two major categories: easy-to-peel and easy-to-tear.
(1) Easy-to-peel easy-to-open films
The easy-to-peel easy-to-open film is a more widely used variety of easy-to-open film, which is used as the cover material for plastic cups, bowls and other packaging containers. The basic principle behind the production of easy-to-peel easy-to-open films is that the peel strength of the film decreases moderately after heat sealing through a specific formula, in order to achieve both effective protection of the packaged goods and the original intention of easy opening; easy-to-peel easy-to-open films are generally multi-layered composite structures, with at least two main layers and a heat sealing layer. The role of the main layer is to give the film high mechanical properties, such as high rigidity, high tensile strength and tear strength, while the main layer of the easy-to-peel easy-to-open film has a high
The melting point of the main layer of the easy-to-peel easy-to-open film allows for a larger melt temperature difference between the main layer and the heat seal layer, thus improving the heat seal processing performance of the film. The heat seal layer is also known as the adhesive layer, and its function is mainly to give the film sealing reliability and the film's ease of peeling. In order to obtain high quality easy-to-peel easy-to-open films, the material of the heat seal layer often uses special adhesives or special formulations; when the requirements of the product are not high, the material of the heat seal layer can also be formulated using specific grades of general-purpose resin. www.susumino. com
(2) Easy-tear, easy-open films
Easy-tear easy-open films are used to manufacture plastic packaging bags that are easy to tear open. Easy-tear easy-open films are currently used in fewer applications and are not well reported in the literature. The ideal easy-to-tear easy-to-open film does not only require a low tear strength, but also requires the film to be torn with a relatively good linear cleavage, that is, when the film bag is opened and sealed, the cracks along the desired direction of linear expansion to prevent irregular cleavage of the broken bag, resulting in the loss of the contents. In addition to a specific formulation (or a specific grade of resin) when preparing an easy-tear easy-open film, an appropriate processing (moderate stretching) is often required to produce a specific orientation of the macromolecules in the film. Tear-prone easy-open films can be either single-layer structures or multi-layer composite films made by laminating a single layer of tear-prone film with a bi-oriented film. www.susumino. com
2. Application of easy-open films
At the beginning, easy-open films were mainly used for after-dinner snacks, jellies and other casual foods. With the advent of the ageing era and the improvement of people's living standards, the application surface is rapidly expanding as easy-open films for the lids of plastic containers such as yoghurt, jelly, jam, milk, pudding, cold drinks, cup noodles, lactic tofu, wave foods, bottled medicines, etc.; and the materials for containers are mainly polypropylene (PP), high-density polyethylene ( HDPE), polyvinyl chloride (PVC), high impact strength polystyrene (HIPS), polystyrene (PS), copolyester (PETG), non-crystalline polyester (APET).
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