Tubular FFS Polyethylene Films: A Solution for Bulk Packaging

Tubular FFS Polyethylene Films (also called FFS sleeves or tubular PE roll stock) are seamless, heavy-duty polyethylene webs engineered for form-fill-seal machines. Unlike premade bags, these tubular films are fed continuously onto vertical baggers, where they are cut, filled and sealed in-line. In modern high-speed packaging of powders, granules or pellets, these films do more than just contain product - they act as active pressure-management layers. Specifically, films with micro-perforations provide controlled venting: tiny engineered holes that let trapped air escape during filling, without sacrificing moisture resistance or bag strength. The result is faster fill cycles, flatter "brick" bags, fewer deformed "pillow" sacks and stronger seals - all without the bulk and risk of macro-perforations.You will find more details on https://www.pp-wovenbags.com/pe-heavy-duty-form-fill-seal-tubular-roll-polyethylene-bags/

In this dossier we dive deep into the design, manufacture, and performance of Tubular FFS Polyethylene Films with micro-venting. We analyze why precise hole patterns matter, how film architecture and processing affect final bag behavior, and where these films deliver value (mineral powders, fertilizers, resin pellets, etc.). We compare VidePak's advanced film solutions with generic offerings, highlighting VidePak's multi-layer coextrusion capabilities, stringent quality controls, and specialized vent patterns. Throughout, we connect questions (like "How small should the vents be?" or "When do holes harm seals?") to engineering answers and measurable outcomes.Regarding VidePak, you wil find them on https://www.pp-wovenbags.com/tubular-ffs-polyethylene-films-with-micro-perforations/

What are Tubular FFS Polyethylene Films?

Tubular FFS Polyethylene Films are polyethylene tubes (often 3-9 layers thick) produced by blown-film extrusion and delivered on large rolls. Unlike flat sheets or premade sacks, they are continuous "sleeves" that run vertically through form-fill-seal (FFS) machines. A typical setup feeds the film by the meter: a bottom seal is made, the tube is filled with product, then a top seal completes the bag. This "endless bag" approach allows on-demand bag length, faster changeovers, and elimination of cutlery seams.

These films are built for heavy-duty use (covering 5-50 kg product, often up to 100 kg in capacity) and industrial environments. They are typically multi-layer coextrusions of high-performance polyethylenes (HDPE, LLDPE, mLLDPE, LDPE, etc.), sometimes including recycled content or UV stabilizers. Layers are tuned: e.g. a high-melt-strength core for bulk and stiffness, plus treated outer skins for printing. VidePak, for instance, makes up to 9-layer coex FFS films, providing "high durability and good thickness uniformity". All Tubular FFS Polyethylene Films share a common feature: they are made of polyolefin (PE), enabling strong seals and (if properly specified) full recyclability as mono-PE.

Key Industry Terms

These films go by many names across the industry. Common aliases include:

• FFS Sleeve - emphasizes form-fill-seal use.
• Tubular PE Roll Stock - refers to the seamless tube shape.
• Continuous Gusseted Film - often called "continuous gusseted film" (with folded sides), especially in North America.
• Heavy-Duty PE Web - highlights thickness (>100 μm) for big sacks.
• Degassing Tubular Sack Film, Breathable PE FFS tubular web, Micro-vented FFS film, Laser-micro-perforated FFS tube, Hot-needle micro-perforated FFS roll, etc.

Regardless of label, the core idea is the same: a self-forming bag material with engineered vents.

Why Micro-Perforations? The Venting Paradox

Features and Insights:

• Hole Diameter Matters: Studies find ~10-100 μm holes are ideal. Below ~10 μm airflow is choked; above ~100 μm particles or even water can pass. In practice, diameters around 60-80 μm are common. For example, a preferred design uses 70 μm holes: small enough that "insects and other contaminants cannot pass", and flour fines (down to 70 μm) won't leak, yet >10 μm holes easily vent air.

• Venting vs. Integrity: More holes = faster venting but weaker film. Each hole is a stress concentrator; a line of holes under a seal could compromise that seal. Thus pattern design is a lever: you tighten holes (reduce diameter, increase density) to tame a stubborn "pillow" problem, or back off (bigger holes, fewer per area) when moisture/moist powder is a concern. Modern engineering views these holes not as damage but as parameters: hole diameter, density, and offset can be tuned like knobs on a machine.

Core Features of Venting FFS Films

Tubular FFS Polyethylene Films with micro-holes are more than just holes. Their feature set is a carefully balanced toolkit of functionalities. Key attributes include:

• Engineered Airflow (Microholes): Holes ~60-80 μm in diameter (typically 0.01-0.02 mm2 each) and very low overall open-area (few hundredths of a percent) create laminar-leaning airflow paths during filling. These precisely sized orifices let air out swiftly under pressure, but block most dust and liquid under static conditions. The shape of hot-needle holes (trumpet rims) or laser-drilled holes can also improve toughness, preventing micro-tears around the aperture.

• Slip/Anti-Block Coatings: To handle fast FFS lines, films use low-migration slip additives and anti-block agents. A typical static/dynamic coefficient of friction (COF) is ~0.20-0.35, so the film glides over forming shoulders and conveyor rails without sticking or jerking. Stable slip keeps print registration consistent and prevents bag pile-ups on the neck rail. Anti-block (often micro-bead silica) ensures the film layers don't fuse together on the roll even though perforations expose more surface area. These coatings are selected to be permanent (non-bleeding), preserving COF over storage and meeting food-contact additive guidelines if needed.

• Mechanical Strength & Material: Despite micro-holes, these films remain tough. The base resin is usually a blend of metallocene LLDPE and LDPE; this tie-chain rich matrix gives high puncture and tear resistance. Typical properties: MD tensile ~35-55 MPa, TD 28-50 MPa (ISO 527); dart impact ~600-1500 g (ISO 7765); Elmendorf tear MD 200-600 mN, TD 400-1200 mN (ISO 6383). To mitigate holes as split starters, holes are staggered (not in a straight row) and avoid the jaw zone. In practice, even a film with ~0.1% open area shows only modest impact on strength - the increase in seal initiation temperature or drop-test failures is minor if the film design (orientation, thickness) is robust.

• Printability: The face skin of the film is corona-treated (≥38-42 mN/m) for ink adhesion. Many producers recommend printing before perforating (especially for laser-drilled films), to keep ink layers intact. If perforating after print, masks or selective plating avoid punching through heavy solids. Primer coatings or special inks compatible with recycling classes may be used near vent zones. The goal is crisp, glossy graphics even around vent fields. VidePak specifies dyne >38 mN/m as a baseline, and monitors dyne decay to guarantee adhesion long after film processing.

Manufacturing: From Resin to Perforated Tubing

Producing high-performance Tubular FFS Polyethylene Films is a controlled sequence - each step affects the final behavior of bags. The key stages are:

• Resin Blending: It starts with selecting the right base PE polymers. Typically a metallocene-based LLDPE/LDPE mix (density ~0.918-0.928, MFR ~0.3-1.2 g/10min) is chosen for a balance of puncture and processability. Filler-worn supply chains often include 20-40% post-consumer recycled (PCR) PE in the core layer (as VidePak reports from its R&D lab). A masterbatch of low-migration slip/anti-block (e.g. 2-6 μm silica, 500-1500 ppm) is added to ensure a stable COF and to prevent blocking, while external layers get anti-block-free mix for print clarity. UV stabilizers or antioxidants are also compounded as needed, with all additives meeting food-contact (EU 10/2011, FDA 21 CFR 177.1520) and RoHS/REACH restrictions.

• Co-Extrusion & Blown Film: The molten polymer goes through a spiral mandrel blown-film die. To achieve uniform thickness and optical quality, the setup often uses Internal Bubble Cooling (IBC) and oscillating haul-offs. Typical blow-up ratios (BUR) are 2.2-3.0, balancing machine direction (MD) vs transverse (TD) orientation. The target layflat width tolerance is very tight (±3-5 mm over the roll) because any bag misalignment would skew perforation zones. VidePak (using German W&H lines) maintains gauge variance within ±5-7%. As the bubble is drawn, an operator may route part of the surface through a corona treater. The treated side (usually interior of bubble) will be printed, so dyne is raised to ≥38 mN/m. Corona power, spacing and amperage are monitored to hold treatment within the target window.

• Embossing (Optional): Some films add embossing rolls (e.g. micro-diamond knurls at the edges) to mechanically reinforce seals and improve slide. Thin embossed ribs (0.2-0.5 mm) along the edges can increase seal seam line roughness and improve jaw grip. VidePak data shows small micro-embossed pockets can boost ASTM F88 peel strength by ~15% and reduce static friction by ∼0.05 units. If used, embossing is done hot on-line before slit-rolling.

• Perforation: This is the defining step. Tubular FFS Polyethylene Films may be perforated using:

• Hot-Needle Perforation: A heated pin or wheel pierces the film, creating a hole with a thermally fused rim. This "trumpet" shape often blunts split initiation. Hot needles run at line speed and are cost-effective. Hole size is controlled by dwell (needle time vs web) and temperature. Typical tolerance is ±10-15 μm.

• Laser Drilling: A CO2 or UV laser ablates holes post-extrusion (often after printing to avoid ink damage). This yields very precise, sharp holes (±5-10 μm tolerance) and can create complex zone patterns via software control. Laser has higher capex, but excels at fine patterns and off-seam holes.

• Punch/Cold-Needle: Less common for high-speed film, but uses a mechanical pin at room temperature. It yields clean holes without heat-affected zones, with tight diameter control. However, it's slower and can burr edges if not finely machined.

• Hybrid: Some converters combine methods. For example, hot-needle might lay a base grid of vents, while a laser then "touches up" certain high-flow bands or printed-over sections.

Regardless of method, the film is driven under the perforator in precise registration: rollers and edge guides keep the web aligned so the holes hit exactly the planned zones. After perforation, quality checks measure actual hole diameters, count per area, and registration vs gusset fold or seal markers.

• Winding & Cure: After perforation, the film is slit to width (e.g. 300-1200 mm flat). Rolls are wound under controlled tension to avoid blocking (especially critical with micro-holes). A dwell time under ambient or mild heat lets slip-migration and dyne stabilize, a process called "roll conditioning." Final rolls are typically marked with open-area fraction, mean hole diameter and pattern description.

• Quality Inspection: Every batch undergoes metrology. Typical tests include:

• Optical Hole Inspection: A microscope or camera scans a sample section to verify hole size distribution and density (often reported as holes/cm2 in each zone).

• Airflow Test: Using a fixture or "flow rig," a known pressure (e.g. 20 mbar) is applied across a film sample to measure flow rate. This yields a pressure-flow curve, which is sensitive to total open area. It's a quick proxy for on-line deaeration performance.

• Thickness Map: A multi-point thickness gauge (ISO 4593) checks uniformity across the web, ensuring within ±5%.

• COF and Dyne: COF (ASTM D1894) is mapped across each roll edge-to-edge to ensure no sticky or too-slippery zones. Dyne pens test surface energy on random spots to confirm print-side treatment.

• Seal Window (ASTM F2029): Small bags are made and sealed under varying conditions to find the optimal seal temperature and to ensure no perforation overlaps the vertical seal.

• Mechanical Tests: Tensile, tear, dart impact (as noted above) are run on film with and without perforations. If values fall outside spec, the pattern or resin may be adjusted.

Contact details:

Email: Info@pp-wovenbags.com
Headquarters Address:No.57 Jinliang Rd, Pudong, Shanghai P.R.C 201323
Website: https://www.pp-wovenbags.com/

__________________________________
About Us:
Established in 2008, VidePak is dedicated to producing high-quality PP woven bags, BOPP woven bags, valve bags, kraft paper bags, HDPE FFS PE bags, and FIBC ton bags. With over 500 employees and more than 25 years of experience in the industrial bag industry, our products are exported to over 70 countries and regions, including Japan, South Korea, Europe, the UAE, Eastern Europe, South Africa, the USA, Brazil, and South America. We adhere to the principles of quality first, innovation-driven development, and customer focus, striving to become an industry leader. To ensure stable and reliable product quality, we utilize equipment from renowned suppliers such as W&H and Starlinger, and are equipped with over 100 circular looms, 16 extrusion production lines, and over 30 laminating and printing machines.

This release was published on openPR.