Air bubble film, production and inspection process


Air bubble film is the most common cushioning packaging material, with low cost, broad usage scenarios, and an excellent cushioning effect.
This article describes a real bubble film world from the dimensions of production principle, raw material ratio, cost analysis, product specifications and product quality inspection.

01 .Air bubble film production principle

The Americans invented the bubble film in the 1950s. Their original intention of creating the bubble film was to develop a new type of wallpaper. It was prevalent to use the chemical raw material polyethylene as the wallpaper material. They used polyethylene to blister out bubbles and covered them with polyethylene on the other side to lock the air, forming a bubble film.

At first, as for wallpaper, it was not popular in the market, and sales were poor. Later, IBM used this material to package computers, making the bubble film popular. After transforming from wallpaper to packaging material, air bubble film finally gained market recognition and is popular to this day.

Diagram of bubble film production process

The core production process of Air bubble film:

① Melting of raw materials: Polyethylene is heated and melted at a high temperature of 230 degrees Celsius, melted into a paste-like resin, and then sent to the film blowing machine.
② Film inflation: The generated bubbles are sucked into a vacuum to form a complete bubble.
③. Film synthesis: The backside of the film (the side without holes) and the front side (the side with gaps) are heated and bonded to form a finished bubble film product.
After forming a stable bubble film product, we generally control the density of the bubble film by adjusting the temperature of each temperature zone and the discharge speed to achieve the outcome we want.

02.Air bubble film Raw material ratio

Polyethylene is a significant category of chemical raw materials. In producing bubble film, we often use LDPE (high-pressure polyethylene) and LLDPE (linear polyethylene) to create bubble film products with qualified product quality through a specific ratio.
Advantages: good flexibility, extension line, transparency, cold resistance and processing performance.
Disadvantages: poor mechanical strength, moisture barrier, gas barrier, and flux resistance; inadequate heat and solar ageing resistance, easy to decompose and discolour under sunlight or high temperature, resulting in performance degradation.
Advantages: high strength, good toughness, muscular rigidity, heat and cold resistance
Disadvantages: poor transparency, dull surface
Calculated based on one ton of raw materials, when using new raw materials, the raw material ratio for producing bubble film products with stable product quality is as follows:
Primary material: LDPE ratio is 20%, which is 200KG; LLDPE ratio is 80%, which is 800KG;
Accessories: 0.2% of an antistatic agent, which is 2KG; 0.5% of an antistatic agent, which is 5KG;

03.Air bubble film product specifications

In theory, as long as the width of the bubble machine is sufficient, customers can customize bubble film products of any specification. The width of the standard bubble machine is 1M, 1.2M, 1.6M, 1.8M, 2M, etc. The width of the bubble machine determines the maximum capacity of the equipment and the entire width of the product.
The common factors that affect the product specifications of the bubble film are the bubble diameter, density, width, weight and number of composite layers:
①. Aperture: small bubble diameter 6mm, height 3mm; medium bubble diameter 10mm, height 5mm; large bubble diameter 28mm, height 10mm;
②. The density is expressed in terms of weight per square, that is, xx grams/square, which is often used to calculate the density of the coil; the density is expressed in squares per kilogram, that is, xx square/kg, which is often used to calculate the density of air bubble film sheets; common Bubble film product density: 40g/square, 50g/square, 60g/square, 80g/square, etc.;
③. Width: The width can be cut within the maximum width of the machine by using the aforementioned sub-rolling equipment. Common specifications are 20cm, 30cm, 40cm, and 50cm.
④. Weight: The weight is affected by the width, density and length of the roll. Generally, to facilitate settlement, an integer is used as the weight specification. The common weight is 1-10KG/roll.
⑤. Number of layers: common single layer, double layer, three-layer, five-layer, etc.; (the diagram is as follows)

Single and double layer bubble wrap

Combining different usage scenarios, we sort out common single-layer bubble film roll products as follows:

Common specifications and use scenarios of air bubble film rolls

04 .Air bubble film quality Inspection

The current industry standard is polyethylene air-cushion film QB1259-1991. The bar divides the bubble film into three categories: Z-type, Q-type, and Y-type, according to the application. Each class has an impact on the product’s bubble diameter and density (square/kg). , Physical properties, appearance performance and other quality indicators make reference standards. At the same time, combined with reference standards, a quality test method was developed. The core contents are listed as follows:
①. Product classification:
Divided into three categories according to use:
a. Z type-for heavy packaging, bubble diameter 10 ~ 25mm, bubble height 3 ~ 10mm;
b. Y type-for general packaging, bubble diameter 4~15mm, bubble height 3~7mm;
c. Type Q---for light packaging, bubble diameter 3 ~ 10mm, bubble height 2 ~ 5mmo
According to the size of the unit mass area, it is divided into two types: Q1 and Q2.
②. Density & limit deviation
Note: Both parties negotiate the specific indicators within the scope.
③Appearance requirements
④Physical properties
⑤ Hygienic performance

Under normal circumstances, after refining the company’s Air bubble film acceptance criteria by industry standards, we follow the steps below to inspect the product quality of Air bubble film:

Step 1: Check whether the colour and smell of the bubble film meet the requirements.
Step 2: Check the single roll weight of the bubble film to determine whether the importance of the bubble film meets the error requirements
Step 3: cut a piece of bubble film and weigh the density to determine whether the density meets the error requirements
Step 4: Check the quality of the bubbles, whether the number of flat bubbles/deflated bubbles meets the quality requirements, and whether there is air leakage/delamination

Generally, during the acceptance process, the product quality inspection shall be carried out in strict accordance with the above steps. If the inspection result meets the quality requirements, the batch of products is qualified.

For more industry consultation, follow Xuanwang.