If you import vacuum compression bags from China, you will encounter a wall of technical jargon: blown film extrusion, dart drop testing, corona treatment, gel count. Misunderstanding a single term can cost you a container of defective product. This glossary covers every technical term you will encounter in factory communications, QC reports, and certification documents.
A–C
- ASTM D1709
- Standard test method for impact resistance of plastic film by the free-falling dart method. Measures puncture resistance.
- Blown Film Extrusion
- The manufacturing process where molten plastic resin is extruded through a circular die and inflated into a thin bubble, then cooled and collapsed into flat film tubing. Used for virtually all vacuum bag production.
- Check Valve
- A one-way valve that allows air to exit but not enter. In vacuum bags, typically a thin flexible membrane inside a plastic housing.
- Co-extrusion
- Simultaneous extrusion of two or more polymer layers through a single die to create a multi-layer film (e.g., PA+PE).
- Corona Treatment
- Electrical discharge treatment that increases the surface energy of plastic film, enabling ink adhesion for printing. Measured in dynes/cm.
D–G
- Dart Drop Test
- Impact resistance test (ASTM D1709). A weighted dart is dropped from a specified height onto stretched film. Higher weight at failure = better puncture resistance.
- Double-Track Zipper
- A sealing mechanism with two parallel interlocking tracks, providing redundancy. Standard on quality bags; single-track is economy grade.
- Dyne Level
- Measure of surface energy. Film needs 38+ dynes/cm for good ink adhesion. Corona treatment raises dyne levels.
- EVOH (Ethylene Vinyl Alcohol)
- A high-barrier copolymer sometimes used as a middle layer in premium vacuum bags for superior oxygen barrier properties. More expensive than standard PA+PE.
- FDA 21 CFR 177.1520
- US regulation covering olefin polymers (PE, PP) for food contact. Required for any vacuum bag marketed as food-safe in the US.
- Gel Count
- Number of unmelted or partially melted resin particles (gels) visible per square meter of film. Lower is better. Premium film: under 5 gels/m².
H–M
- HS Code (Harmonized System)
- International product classification code for customs. Vacuum storage bags typically fall under 3923.21 (sacks and bags of polymers of ethylene) or 3923.29.
- Heat Seal Strength
- The force required to separate a heat-sealed joint. Measured in N/15mm. Minimum acceptable: 30 N/15mm for vacuum bag bottom seals.
- LDPE (Low-Density Polyethylene)
- A flexible, tough PE variant used in the inner sealing layer of vacuum bags. Lower melting point than HDPE, making it ideal for heat sealing.
- LLDPE (Linear Low-Density Polyethylene)
- PE variant with higher tensile strength and puncture resistance than LDPE. Commonly used in premium vacuum bag inner layers.
- Micron (µm)
- Unit of film thickness. 1 micron = 0.001 mm. Common vacuum bag thicknesses: 50µ (economy), 70µ (standard), 90µ (heavy-duty).
- MOQ (Minimum Order Quantity)
- The smallest production run a factory will accept. For custom-printed vacuum bags: typically 5,000–10,000 units per SKU.
N–R
- Oxygen Transmission Rate (OTR)
- The rate at which oxygen passes through film. Measured in cc/m²/day. Lower OTR = better air barrier. PA+PE: ~25–40 cc/m²/day.
- PA (Polyamide / Nylon)
- The outer layer in PA+PE vacuum bags. Provides strength, puncture resistance, and oxygen barrier. Typical thickness: 15–20 microns.
- PE (Polyethylene)
- The inner sealing layer in vacuum bags. Provides heat sealability, flexibility, and moisture barrier. Typical thickness: 30–50 microns.
- PET (Polyethylene Terephthalate)
- Alternative outer layer used in PET+PE bags. Higher clarity than PA but lower puncture resistance. Common in economy-grade bags.
- PPWR (Packaging and Packaging Waste Regulation)
- EU regulation effective 2026–2027 requiring all packaging to be recyclable by 2030 and setting recycled content minimums. Impacts vacuum bag packaging design.
- REACH (EC 1907/2006)
- EU regulation on Registration, Evaluation, Authorisation and Restriction of Chemicals. Vacuum bags sold in the EU must comply with REACH substance restrictions.
S–Z
- Slip Agent
- Additive (typically erucamide) that migrates to the film surface and reduces friction, making bags easier to open and handle.
- Tensile Strength
- The maximum stress a film can withstand while being stretched before breaking. Measured in MPa. Vacuum bag film typically: 25–40 MPa (MD), 20–35 MPa (TD).
- Tie Layer / Tie Resin
- Adhesive polymer layer that bonds PA to PE in multi-layer films. Without it, the layers delaminate.
- UV Stabilizer
- Additive that prevents polymer degradation from ultraviolet light exposure. Important for bags stored in sunlight or used outdoors.
- Water Vapor Transmission Rate (WVTR)
- The rate at which moisture passes through film. Measured in g/m²/day. Lower is better for long-term storage.
- Zipper Slider
- A plastic clip that slides along the double-track zipper to ensure complete closure. Included with premium bags; economy bags may omit it.
Common Factory Floor Abbreviations
| Abbreviation | Meaning | Context |
|---|---|---|
| BOPP | Biaxially Oriented Polypropylene | Used for retail packaging overwrap, not the bag itself |
| MD / TD | Machine Direction / Transverse Direction | Film properties differ by direction; always ask for both values |
| COF | Coefficient of Friction | How slippery the film surface is; affects bag opening and handling |
| AQL | Acceptable Quality Level | QC sampling standard; AQL 2.5 = reject batch if defects exceed 2.5% |
| GMP | Good Manufacturing Practice | Factory hygiene and process standards; ask for GMP certificate |
Sources: ASTM International standards; FDA regulations; EU REACH/PPWR documentation; packaging industry technical references.