The retort bag is made of multi-layer film materials, which are made into a certain size packaging bag by dry lamination or co-extrusion lamination.Its constituent materials are usually divided into 9 types. The retort bags made must be able to withstand high temperature sterilization, and its structural design should also meet the requirements of good heat sealability, heat resistance, water resistance, high strength and high barrier performance. Next, the professional packaging manufacturer Lucky Time Pack will analyze the materials used as retort bags.
PET film
BOPET film is made by PET resin extruded by T film and then biaxially stretched, and has excellent performance. For example:
Good mechanical properties. The tensile strength of BOPET film is the highest among all plastic films. The extremely thin products can meet the needs, with strong rigidity and high hardness.
Cold resistance and excellent heat resistance. The applicable temperature range of BOPET film is from 70 to 150°C. It maintains excellent physical properties in a wide temperature range and is suitable for most product packaging.
Good barrier performance. It has excellent water and gas barrier properties, its water barrier rate is similar to PE, and its ventilation coefficient is extremely small. It has extremely high barrier to air and odor, and is one of the fragrance-preserving materials.
Resistant to grease and most solvents, dilute acids, dilute alkalis, etc. These properties make PET films ideal for retort bags.
BOPA film
BOPA film is a biaxially stretched film, which can be obtained by simultaneous biaxial stretching with blow molding. The characteristics of BOPA film are as follows:
Excellent toughness. The tensile strength, tear strength, impact strength and burst strength of BOPA film are one of the best among plastic materials.
Outstanding flexibility and not easy to be pierced by the contents are the characteristics of BOPA. It has good flexibility and makes the packaging bag feel good.
It has good barrier properties, good fragrance retention, and resistance to chemicals other than strong acids, especially oil. So it’s quite suitable for retort bags.
The temperature range is wide, the melting point is 225℃, and it can be used for a long time between -60~130℃. BOPA film’s mechanical properties remain stable at low and high temperatures.
The performance of BOPA film is greatly affected by humidity, especially the dimensional stability and barrier properties. After being damp, in addition to wrinkle, generally transverse elongation and longitudinal shortening, elongation up to 1%.
In addition, common materials used for retort bags are CPP film, aluminum foil, ceramic evaporation film, PEN film, BOPI film, PBT film, TRX film, etc. As a professional food packaging company, Lucky Time Pack has a lot of experience in the production and design of retort bags. Lucky Time Pack is committed to providing all customers with packaging that meets their standards, hoping to become a supplier who can be believed by all customers.