Courier packages bring us food, clothing, and everyday essentials.
Consequently, various types of courier packaging bags have become commonplace items for us.
And those that are thrown away immediately after the delivery package is opened
The delivery packaging bags closely tied to the products,
How much do you actually know about them?
Now, Sister Xiaomin will take you on a tour.
From From the perspective of packaging inspection Let's get to know each other again. Courier packaging bag
1. Thickness
The thickness of the membrane.
Xiaomin on Testing: You can learn the specifications of the plastic film you produce.
2. Thickness Deviation
Maximum allowable manufacturing tolerance for plastic film thickness.
Xiaomin Talks Testing: Thickness tolerance testing can promptly identify deviations in plastic film thickness, enabling timely corrective actions to prevent large-scale product defects and minimize losses.
The maximum initial stress observed during the tensile test.
Xiaomin on Inspection: Plastic film is typically pre-stretched before coming into contact with goods, ensuring that the film is subjected to a consistent tensile force as it wraps around the product—and that this force is evenly distributed across the entire width of the film.
4. Nominal Strain at Fracture
The fracture nominal strain refers to the maximum strain a material reaches before fracturing.
Xiaomin Talks Testing: Nominal strain at break is an important performance indicator for plastic films, enabling the evaluation of their toughness, ductility, and other key characteristics.
5. Right-Angle Tensile Strength
Tensile tear strength refers to a material's ability to undergo tearing failure when subjected to stress.
Xiaomin Talks Testing: Since the film may be subjected to various forces during packaging, transportation, and use, potentially leading to tears or damage, testing its tear resistance is essential for determining the material's durability—and also serves as a critical benchmark for quality assessment.
Thermal seal strength is used to evaluate the quality of heat sealing between films—or between a film and other substrates—and the performance directly determines the effectiveness of the heat seal.
Xiaomin on Testing: Heat-seal strength directly affects the appearance and sealing performance of courier bags. To ensure that items can withstand external forces during packaging, transportation, storage, and consumption—preventing cracks, leaks, and ultimately protecting the product—it’s crucial that the sealed areas of plastic film packaging materials possess sufficient strength and airtightness. As such, heat-seal strength in plastic film bags is a key testing indicator.
7. Pendulum Impact Resistance
Used to measure the resistance of plastic films under impact loads.
Xiaomin Talks Testing: Simulating real-world scenarios where plastic films are subjected to impacts, such as items being dropped or experiencing mechanical shocks. These tests help assess the film's impact resistance, ensuring it meets application requirements—like preventing damage during packaging, transportation, and use—by withstanding unexpected forces without breaking.
It is an indicator that measures the magnitude of puncture resistance a material can withstand under specific conditions.
Xiaomin on Testing: The purpose is to evaluate the strength and durability of plastic films when subjected to puncture. This helps ensure that the films can withstand various piercing forces during transportation, handling, and use—such as punctures from sharp objects, friction from items, and impacts—without compromising their integrity.
9. Light Transmittance
It refers to the ability of light to pass through a medium—a measure expressed as the percentage of light flux transmitted through a transparent or translucent material relative to the incident light flux.
Xiaomin on Testing: The translucent film is tested for its light transmittance to evaluate how well the film allows light to pass through, ensuring that the product meets performance standards for light transmission—and ultimately guaranteeing both quality and safety.
10. Surface Requirements
The surface requirements for plastic films involve several aspects, including appearance, transparency, thickness, glossiness, and surface tension.
Xiaomin Talks Testing: The surface of the courier bag should be smooth and even, free from noticeable damage or dirt. It must not have defects such as bubbles, punctures, poor plasticization, hard lumps, or wrinkles. Additionally, the bag should be suitable for adhering barcode labels and shipping documents with adhesive backing, ensuring that once cured, these labels remain firmly in place without any significant odor.
11. Production Requirements
Production requirements refer to a set of specific standards or regulations that must be met during the manufacturing or production process of courier bags.
Xiaomin on Testing: The production requirement testing is conducted to ensure the quality and safety of courier bags, enhance the efficiency and reliability of delivery services, and meet relevant industry standards as well as customer expectations. Courier bags must feature three-sided sealing with secure closures that can withstand the required load capacity. Additionally, a sealing flap should be left at either the top-right corner or the upper edge of the bag’s front panel.
The sealing requirement refers to a set of specific standards or regulations that must be met during the sealing process of courier bags.
Xiaomin on Inspection: This effectively prevents courier bags from being opened or torn during transit, ensuring the safety and integrity of the items inside. It also safeguards contents from moisture, dust, and other environmental threats. The sealing flap should be at least 25mm wide, and the tape used on the courier bag must have a peel strength of no less than 5 N/cm—meaning that after adhering, it should visibly deform when peeled apart.
Heavy metals pose certain risks to human health and the environment. Standards require the detection of lead, mercury, cadmium, and chromium, with maximum allowable levels set at or below 100 mg/kg.
Xiaomin Talks Testing: This test determines whether lead, mercury, cadmium, or chromium—these heavy metals—have been added to the plastic film's raw materials or during the manufacturing process, and whether their concentrations exceed the relevant standards, ensuring safety for both people and the environment.
Phthalate substances exhibit chronic toxicity, mutagenicity, carcinogenic effects, and reproductive and developmental toxicity in both animals and humans. They can enter the human body through inhalation, ingestion, and skin contact, posing serious risks to health.
Xiaomin on Testing: This test determines whether phthalate substances were added to the plastic film's raw materials during production, and whether their concentration exceeds the relevant standards.
Solvent residues in plastic film packaging typically arise from inks, solvents, and the production process, which may involve significant use of organic solvents. The content of these organic solvents is tested according to standard requirements.
Xiaomin on Testing: This test allows you to quickly determine whether plastic films contain residual solvents, which plays a critical role in ensuring product safety. The total solvent residue must be less than 10 mg/㎡, with benzene-based solvents accounting for less than 3 mg/㎡—helping minimize the environmental impact of organic solvents.
16. Limit Requirements for Specific Substances (Biodegradable Plastics Requirement)
It refers to the maximum allowable concentration of a specific substance. In the field of environmental protection, the limit for a particular substance indicates the largest amount of pollutant that the entire ecosystem can safely tolerate.
Xiaomin on Testing: In addition to heavy metals, solvent residues, and phthalates, the biodegradability of courier packaging bags also requires testing against regulatory limits for heavy metals such as zinc, copper, nickel, cadmium, lead, and mercury.
