Cross-linked Shrink Film Application Guide

2023-04-10 11:31:44 Zhejiang Zhongcheng Packing Material Co., Ltd Viewd 383

cross linked pof shrink film is an important material that plays a vital role in several industries. It is a polymer film with a modular structure that forms a three-dimensional network structure through cross-linking reactions, resulting in higher strength and durability. In this paper, we present the definition, types, advantages and disadvantages of cross-linked films as well as their applications, manufacturing process, market overview and environmental impact. 


What are the characteristics of cross-linked films?

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Cross-linked film is a polymeric material with high strength, durability and permeability that is used in a wide range of applications in the packaging, medical, agricultural and electronics industries. It is a film formed by cross-linking multiple polymers with a highly three-dimensional network structure, which makes it very durable and resistant to damage. 


What is a cross-linked film? 


A cross-linked film is a polymer material that is manufactured by adding a cross-linking agent to form a three-dimensional network structure through a cross-linking reaction. The cross-linking effect increases the strength and durability of the material while decreasing the plasticity of the material. Cross-linked films can be classified into linear cross-linked films, branching cross-linked films and network cross-linked films depending on the material construction method and application requirements. 


Linear cross-linked films have a relatively simple structure, formed by straight chains connected by a single cross-linking point; branch cross-linked films are formed by multiple straight chains cross-linked together; and network cross-linked films are formed by a complex network of several chains and cross-linking points. Different types of cross-linked films have different properties and applications. 


The advantages of cross-linked films are their high strength, durability, permeability, and chemical resistance, as well as their ability to withstand higher temperatures and pressures. However, cross-linked films have the disadvantage of not being flexible enough and deformable. 


What is the difference between cross-linked films and other shrink films?

Cross-linked films are films that have been chemically or physically treated so that the polymer chains in the film cross-link to form a network structure. Shrink films, on the other hand, are films that have been shrunk using heat or stretching, etc. The following are the differences between cross-linked and shrink films:

Feature

Cross-linked Film

Shrink Film

Manufacturing method

Manufactured through chemical or physical treatment

Manufactured through heating or stretching, etc.

Effect

Cross-linked structure strengthens strength and stability

Forms tight packaging through shrinkage

Characteristics

High temperature stability and mechanical strength

Good shrinkage performance and transparency

Application areas

Electronics, medical equipment, etc.

Food, pharmaceuticals, cosmetics, etc.

Applications of cross-linked films 


1. in the food industry 


Cross-linked films are widely used in the food industry for their excellent chemical stability and mechanical properties, and their ability to withstand high-temperature heating, heat sealing, and cooking operations. Common applications include various types of packaging, such as heat shrink shrinking chip bags, cling film, stretch film, etc. Cross-linked films are also widely used in molds for meat, cakes, bread, and other food products to facilitate making them into the desired shapes.


2. In the medical industry 


Cross-linked films are also widely used in the medical industry, mainly in artificial organs, drug delivery and medical dressings. Cross-linked films are particularly suitable for artificial organs, such as artificial blood vessels and cardiovascular stents, because they can naturally combine with human tissues. Also, because of their good chemical stability, cross-linked films are easy to disinfect and clean in daily hospital operations.


3. In agriculture 


As an important material in the agricultural industry, cross-linked films are mainly used in liquid fertilizer packaging, greenhouse mulch and floor coverings. The use of cross-linked films for liquid fertilizer packaging ensures that the fertilizer does not corrode and has good durability, thus maintaining its effectiveness over a long period of time. Cross-linked films covering greenhouses can mitigate damage to plants from high temperatures while preventing small insects and weeds from attacking plants; in addition, mulch films can be manufactured with cross-linked film technology to prevent weed growth and improve crop yields.


4. In the electronics industry 


Cross-linked films are also widely used in the electronics industry for circuit boards, electronic components, and flat panel displays. Its main role is to protect electronic components safely and can improve the stability of the entire circuit board or display. Cross-linked films can also be used to produce electronic components such as capacitors and battery cases.


The manufacturing process of cross-linked films 


The manufacturing process of cross-linked films mainly includes selecting the appropriate raw materials, mastering the appropriate cross-linking process and developing the corresponding quality control measures. 


1. Different methods for different types of films 


Different types of cross-linked films have different requirements in the manufacturing process. For example, linear cross-linked films and branch cross-linked films can be cross-linked at high temperatures by a method similar to hot-melt, which will allow the original linear structure to create cross-linked points, resulting in a cross-linked film with a rich structure. The manufacture of network cross-linked films, on the other hand, requires the use of special raw materials, the introduction of functional groups corresponding to cross-linking, and the formation of a network structure by the action of cross-linking agents. 


2. Raw materials used 


Different industries and applications require different raw materials for the manufacture of cross-linked films. For example, in the food packaging industry, cross-linked films are usually made of polyethylene, polypropylene and PET; in the medical industry, polyurethane, polylactide and polycaprolactone are mainly used; while in the electronics and agricultural industries, polyamide and polyamide ester are used. 


3. Quality control measures 


Quality control measures are essential in the manufacture of cross-linked films. By controlling parameters such as extrusion temperature, material volume, plate pressure, and product speed of the material, visible bubbles, oxidation, or other forms of damage or defects in the film can be effectively avoided. Sampling and quality monitoring of the products should also be performed so as to ensure stable and reliable product quality.

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Properties of cross-linked films 

Parameter

Description

Material

Low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), polypropylene (PP), etc.

Thickness

0.012-0.15 mm

Width

100-2000 mm

Length

Customized according to customer requirements

Surface tension

38-42 dyn/cm

Tensile strength

≥27 MPa

Elongation at break

≥450%

Heat shrinkage rate

Vertical ≤5%, horizontal ≤2%

Maximum use temperature

85℃

Puncture resistance

≥1.5 N

Transparency

≥90%

Moisture regain

≤1%

Testing methods

ASTM D882, ASTM D1922, ASTM D2732

Certification standards

FDA, EU RoHS

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  1. Excellent gloss and clarity with retail appeal

  2. Robust and durable seals on various sealing systems

  3. High tensile strength and tear resistance for added toughness

  4. Consistent processability with semi-automatic and automatic packaging machines

  5. High shrinkage allows film to fit tightly to irregular shapes

  6. Non-corrosive seals with no fumes or wire buildup

  7. Good resistance to burning despite tunnel temperature changes

  8. Suitable for a wide range of applications - multi-pack, toys and games, baked goods, printed materials

  9. Meets FDA and USDA regulations for direct contact food packaging

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