Optimizing Your Autobag System: The Science of Choosing PE, PP, and Co-Ex Films

Imagine this: You have invested thousands in a high-speed Autobag® or Sharp® system. The machine is running at 40 bags per minute, and suddenly—JAM. The film snaps, or the seal fails, or the bag just refuses to open.

The problem often isn't the machine. It's the material.

Choosing the right film—Polyethylene (PE), Polypropylene (PP), or Co-Extruded (Co-Ex)—is not just about price. It is about physics. The right choice can increase your throughput by 20% and reduce material costs; the wrong choice can shut down your production line.

In this guide, Adsure’s engineering team breaks down the molecular differences, machine performance, and best applications for each film type.

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1. Polyethylene (PE): The Versatile Workhorse

LDPE (Low-Density Polyethylene) and LLDPE (Linear Low-Density Polyethylene) are the industry standards for 80% of auto-bagging applications. They offer the best balance of flexibility, seal strength, and cost.

Why Choose PE?

• Superior Toughness: Unlike brittle films, PE stretches before it breaks. It is ideal for bulky or irregularly shaped items.

• Wide Sealing Window: PE melts and seals reliably across a broad temperature range, making it forgiving for operators who aren't machine experts.

  
  

The "Science" Factor: COF (Coefficient of Friction)

This is where generic bags fail. For a film to run smoothly on drive rollers without slipping or jamming, its COF must be precise.

• Too High (Sticky): The bag drags, causing misfeeds and length errors.

• Too Low (Slippery): The bag "telescopes" on the roll and drifts off-center.

• Adsure Advantage: We engineer our PE films with a specific slip agent formulation to maintain a consistent COF, ensuring high-speed tracking stability on Autobag AB 180/500/850S systems.

Best For: Hardware kits, e-commerce fulfillment, instruction manuals.

2. Polypropylene (PP): The Retail "Crystal"

If your product needs to sparkle on a retail shelf, you need Polypropylene (PP). It is the material of choice for "high-end" presentation.

Why Choose PP?

• Optic Clarity: PP is glass-like. It allows consumers to see every detail of a jewelry piece, toy, or garment without the "haze" typical of PE.

• Stiffness: PP bags are crinkly and stiff. They stand up straight on peg hooks and don't sag, offering a premium look that enhances your brand image.

  
  

The Trade-Off

• Brittleness: PP has poor tear resistance. If you puncture it with a sharp screw, the bag will likely split open entirely. It is not recommended for heavy or sharp industrial parts.

• Static Sensitivity: PP is naturally prone to static buildup, which can cause light items (like seeds or small electronics) to stick to the bag walls. Adsure counters this with high-grade anti-static additives to ensure smooth opening.

Best For: Jewelry, retail apparel, stationery, craft supplies.

3. Co-Extruded Films (Co-Ex): The Performance Beast

Why settle for one property when you can have three? Co-Extrusion creates a multi-layer "sandwich" film that outperforms mono-layer films.

The 3-Layer Advantage

• Outer Layer: Optimized for printing and controlled friction (COF) for machine feeding.

• Middle Layer: The core strength. We use tough resins here to provide puncture resistance, allowing you to down-gauge (e.g., replace a 3-mil PE bag with a stronger 2-mil Co-Ex bag), saving material costs.

• Inner Layer: Engineered for "Hot Tack"—the ability to seal instantly and hold heavy products even while the seal is still hot.

  
  

Application Spotlight: Opaque Mailers

For e-commerce privacy (HIPAA compliance or high-value items), Co-Ex is the only solution. We extrude a white outer layer for clean labeling and a grey/black inner layer to block 100% of light.

Best For: E-commerce shipping bags, heavy automotive parts, medical devices.

4. Sustainability: The New Decision Factor

In 2026, material selection isn't just about function; it's about your carbon footprint.

• Recyclability: Standard PE and Co-Ex PE films are Class 4 recyclable. Even our 3-layer films are "Mono-Material" (all PE-based), ensuring they enter the same recycling stream without contamination.

• Recycled Content (PCR): Adsure offers GRS Certified PCR (Post-Consumer Recycled) films. Thanks to our 3-layer technology, we can bury the recycled resin in the middle layer, keeping the outer surface smooth and printable—solving the common "rough surface" issue of recycled bags.

  
  

Decision Matrix: Choosing Your Champion

Feature	Polyethylene (PE)	Polypropylene (PP)	Co-Extruded (Co-Ex)
Clarity	Good (Slight Haze)	Excellent (Glass-like)	Variable (Clear or Opaque)
Puncture Resistance	High	Low (Brittle)	Very High
COF / Run Speed	Excellent	Good (Static risk)	Excellent
Sealing Ease	Easy	Difficult (Narrow Temp)	Superior (Hot Tack)
Cost Efficiency	Lowest Cost	High Cost	Medium (Savings via down-gauging)
Best Use Case	General Industrial / Bulk	Retail Display / Jewelry	E-commerce / Heavy Parts

Summary: Stop Paying for "Hidden Costs"

Choosing the wrong film doesn't just cost you a few cents per bag—it costs you in downtime, wasted labor, and damaged product returns.

• Need speed and economy? Go with PE.

• Need shelf appeal? Go with PP.

• Need strength and privacy? Go with Co-Ex.

  
  

Still Unsure? Let Your Machine Decide.

Don't guess. Test. [Request a Free Sample Kit] containing all three material types. Run them on your Autobag® or Sharp® machine and see the difference in COF and seal quality for yourself.

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FAQ

Q1: Which film offers the best clarity for retail display: PE or PP?

Polypropylene (PP) is the clear winner for retail aesthetics. It offers a "sparkle" and glass-like clarity that makes products pop on the shelf, which is why it's preferred for apparel and jewelry. However, standard Polyethylene (PE) is slightly hazier but far more durable and resistant to tearing. If your priority is shelf appeal, choose PP; if it's shipping protection, stick to PE or Co-Ex

Q2: Can I save money by switching to Co-Extruded (Co-Ex) film?

Surprisingly, yes. While the manufacturing technology is more advanced, Co-Ex films use 3 layers of material, allowing for "down-gauging" (using a thinner film without sacrificing strength). For example, a 2.5 mil Co-Ex bag often matches the puncture resistance of a 4 mil Mono-layer PE bag. This reduces your material usage by ~30%, lowering both cost per bag and shipping weight.

Q3: Why does my auto-bagger jam when I switch to PP bags?

PP is naturally stiffer and more prone to static buildup than PE, which can cause bags to stick to the machine’s feed rollers or cutter. To fix this, Adsure treats our PP films with specific slip agents and corona treatments to optimize the Coefficient of Friction (COF). This ensures they run smoothly on high-speed machines like the Autobag® 500 or Sharp® SX™ without "flying" or misfeeding.

Q4: Are multi-layer Co-Ex films recyclable?

Yes, as long as the layers are in the same polymer family. Adsure’s Co-Ex films are typically made from 100% Polyethylene variants (e.g., HDPE/LDPE/LLDPE layers), qualifying them for standard Recycle Code 4 (LDPE) streams. We also offer GRS-certified Co-Ex films where the middle core layer contains 30-50% Post-Consumer Recycled (PCR) resin, keeping the outer layers virgin for perfect printing and sealing.

Q5: Do I need to change my machine settings when switching between PE and Co-Ex films?

Generally, yes. Because Co-Ex films often have better "Hot Tack" (seal strength while hot) properties, you can typically lower your seal temperature and dwell time. This not only speeds up your cycle time (increasing bags per minute) but also extends the life of your heater bar and PTFE Teflon tape. Always run a test batch to find the "sweet spot" settings.