Integrated solution for plastic shopping bag detection based on GB/T 21661-2025 by Sanquan Zhongshi

Plastic shopping bags, as one of the most common load-bearing products in retail, distribution, and daily life, have always been the focus of quality supervision for their safety, reliability, and durability during use. With the official release of GB/T 21661-2025 "Plastic Shopping Bags" standard, enterprises have put forward clear requirements for the control of physical properties such as thickness deviation, sealing quality, and load-bearing capacity in the production inspection process. The accuracy and stability of corresponding testing instruments also directly affect whether the testing results comply with the standard requirements.

This article combines standard requirements to analyze in detail the key physical testing items of plastic shopping bags, and introduces the supporting testing instruments provided by Sanquan Zhongshi and their application advantages.

1、 Scope and classification of plastic shopping bags

According to GB/T 21661-2025, plastic shopping bags are bag products made of traditional plastic resins or plastic composite materials, with carrying structures, used for storing and carrying goods in sales venues.

The standard divides shopping bags into:

• Shopping bags for food contact: may come into contact with food and must meet stricter safety requirements

• Non food contact shopping bags: do not come into direct contact with food

This standard does not apply to:

• Non carrying plastic bags such as continuous roll bags and broken bags

• Starch based, biodegradable plastic shopping bags

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2、 Thickness deviation detection (key basic indicator)

The thickness of plastic shopping bags directly affects their load-bearing capacity and durability. The standard provides clear provisions for thickness limit deviation and average thickness deviation.

Recommendations for thickness measurement methods and instruments

Thickness measurement shall be carried out in accordance with GB/T 6672.

After cutting open the sample, lay it flat on a single layer and measure at least 8 points in the width direction of the bag.

Recommended instrument: Sanquan Zhongshi CHY-HS plastic shopping bag thickness gauge

• Resolution up to 0.1 μ m, widely used in film and aluminum foil production enterprises, quality inspection institutions and other units

• Measurement stability is superior to similar contact thickness measuring equipment

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3、 Physical and mechanical performance testing (load-bearing and impact resistant core parts)

1. Lifting test

SPL-50S Bag Fatigue Testing Machine for Sanquan Zhongshi

The lifting test is used to verify whether the shopping bag has sufficient durability when carrying goods.

Test conditions (standard regulations):

• Vibration distance: 30 ± 2 mm

• Vibration frequency: 2.2 ± 0.2 Hz

• Cycle times: 3600 times

• Test quantity: 3 bags

• Qualification requirement: None of the 3 bags are broken

Characteristics of SPL-50S Bag Fatigue Testing Machine:

• Four column structure, stable results, precise and controllable test frequency

• Can simulate the fatigue conditions during the actual shopping and carrying process

• Suitable for batch testing in manufacturing enterprises

2. Drop test

DL-2000 Drop Testing Machine for Sanquan Zhongshi

Used to evaluate the impact and rupture resistance of shopping bags when carrying objects.

Standard requirements:

• Load no more than 2/3 of the effective volume of simulated objects (rice grains, sand)

• Falling height: 0.5 meters (free fall)

• Ground: hard, smooth

• Qualification requirements: The bag body must be free from breakage and leakage of materials

DL-2000 can achieve stable single free drop testing with reliable repeatability.

Note: This test is not required for shopping bags with special purposes (such as beverage bags) where stress concentration is caused by local heat sealing structures.

3. Sealing strength test

RFY-05 heat sealing tester and XLW-500N sealing strength tester for Sanquan Zhongshi

The sealing area is the most prone to breakage in shopping bags, and the sealing strength is an important indicator for quality judgment.

Test basis: QB/T 2358, requirements:

• Test speed: 300 ± 50 mm/min

• Sample quantity: ≥ 3

• Take the average as the result

• The sample should avoid the folded edges and bottom sealing areas

The RFY-05 heat sealing tester from Sanquan Zhongshi provides standardized preparation of heat sealing samples, while the XLW-500N sealing strength tester achieves high-precision tensile and sealing strength testing, both of which can form a complete sealing performance testing scheme.

4. Dart impact test

BMC-AB Dart Impact Tester for Sanquan Zhongshi

Used to evaluate the damage resistance of shopping bag film under instantaneous impact.

Standard requirements (GB/T 9639.1 Method A):

• Dart head diameter: 38 ± 1 mm

• Falling height: 0.66 ± 0.01 m

• Using the fixed dart quality method instead of the step method

• Sample quantity: 10 pieces

• A non rupture count of ≥ 8 pieces is considered qualified

The drop dart impact tester BMC-AB performs outstandingly in terms of dart stability, detection efficiency, and repeatability, and can meet the high standard impact testing requirements of thin films.

4、 Sanquan Zhongshi: Comprehensive solution for plastic shopping bag detection

As a research and manufacturing enterprise specializing in packaging material testing instruments, Sumspring has been deeply involved in the industry for nearly 20 years and has formed a product system covering multiple fields such as film, plastic bags, food packaging, and pharmaceutical packaging. The company has multiple independent and software copyrights, and has passed ISO 9001 quality system certification and "high-tech enterprise" certification, with significant advantages in standardized instrument research and development.

For the full project testing of plastic shopping bags GB/T 21661-2025, Sanquan Zhongshi can provide:

• Thickness detection: CHY-HS thickness measuring instrument

• Lifting fatigue test: SPL-50S bag fatigue testing machine

• Drop performance test: DL-2000 drop testing machine

• Sealing strength test: RFY-05 heat sealing tester+XLW-500N sealing strength tester

• Dart impact test: BMC-AB Dart impact tester

Covering all physical and mechanical performance requirements in the standard, providing a complete testing plan for enterprise production inspection, quality control, and regulatory sampling.