A Complete Guide to PE Flat Bags

Basic Definition and Characteristics

PE flat bags are flat plastic bags made primarily of Polyethylene, featuring a straight bag opening without handles or self-adhesive seals. They are also known as "inner liners" or "lining bags".

Appearance Features

Milky white or translucent, the effect is more obvious when stacked in multiple layers

• Smooth to the touch like waxed surface, with a crisp sound when shaken

• Combustion characteristics: Flammable, with a yellow flame, wax-like drippings, and a candle-burning odor

Material Classification and Differences

PE flat bags are divided into three main categories based on the density and structure of raw materials:

Differences between High-Pressure and Low-Pressure PE

• High-Pressure PE (LDPE): Soft and glossy to the touch, with a slight friction sound

• Low-Pressure PE (HDPE): Hard and matte to the touch, with a distinct friction sound

Manufacturing Process

Core Process

1. Raw material preparation: PE resin pellets (food-grade or industrial-grade)

2. Film blowing: Heating and melting the pellets via an extruder and blowing them into tubular film

3. Slitting: Cutting the tubular film into flat film of the required width

4. Bag making: Heat-sealing the bottom (temperature: 120-160℃, pressure: 0.2-0.4MPa)

5. Trimming: Cutting the film into individual bags according to specifications

Customization Options

• Color: Transparent, milky white, colored, etc.

• Printing: LOGOs and text can be added (using eco-friendly water-based inks)

• Special functions: Perforated for breathability, anti-static, anti-fog, etc.

Application Fields

Food Industry

• Packaging bread, snacks, dried foods, fruits and vegetables

• Compliant with food-grade standards, safe and non-toxic

Industry and Electronics

• Packaging small parts and electronic components (anti-static type available)

• Packaging chemical products (resistant to acid and alkali corrosion)

Daily Necessities

• Storage of garments, shoes, hats and home textiles (dust and moisture proof)

• Organization of household sundries and moving storage

Medical and Other Fields

• Packaging of medical devices and pharmaceuticals (non-toxic and sterile)

• Gift packaging and jewelry display

Performance Advantages

1. Lightweight and portable: Low weight, no extra burden when carried

2. Water and moisture proof: Blocks water vapor and protects contents from dampness

3. Excellent toughness: Tear and rub resistant, not easy to damage

4. Chemical stability: Resistant to acids and alkalis, no reaction with most chemicals

5. Cost-effective: Low manufacturing cost, suitable for mass use

6. Transparent and visible: Facilitates viewing of contents and improves selection efficiency

7. Low temperature resistance: Can be used at a minimum temperature of -70℃ to -100℃

Environmental Performance

• Recyclable: PE material is 100% recyclable and reusable, complying with environmental standards

• Degradable: Some PE bags added with degradation masterbatch can decompose in the natural environment

• Single-material design: Pure PE structure is easier to recycle, avoiding the recycling difficulties of composite materials

Usage Notes

• Temperature limit: Ordinary PE flat bags are suitable for use at -20℃ to 70℃ and are not for high-temperature items

• Load capacity: Depends on thickness, generally not exceeding 5kg; HDPE material or thickened versions are recommended for heavy items

• Sealing method: No built-in seal, need to be tied with rope, taped or heat-sealed

• Food use: Must select food-grade PE material, avoid contact between industrial-grade material and ready-to-eat food

Purchasing Guide

Characteristics of High-Quality PE Flat Bags

• Uniform appearance without air bubbles, impurities or obvious lines

• High transparency (unless specially required), no fog or turbidity

• Firm heat-sealed edges without missing or weak seals

• Moderate hand feel, non-sticky and odorless

Summary

With the characteristics of lightness, moisture resistance, cost-effectiveness and multi-functionality, PE flat bags have become an "unsung champion" in the modern packaging field, widely used in the food, garment, electronics, medical and other industries, as well as daily household storage. When selecting, the material, thickness and specifications should be chosen rationally according to the characteristics of the contents (weight, humidity, shape) and usage scenarios, to balance practicality and environmental considerations.