PP Woven Bags With Inner Liners
A woven bag stops product escaping through the fabric. A liner stops moisture, oxygen and contamination getting in — and stops fine powder sifting out through the weave. If you pack flour, sugar, milk powder, chemicals or fertiliser, the liner is the part your customer will judge you on.
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Liner types we produce
| Sewn-in PE liner | A polyethylene liner stitched into the bag so it cannot shift or be left out. Standard for powder, flour and chemicals. |
|---|---|
| Loose liner, cuffed at the mouth | A separate liner folded over the bag mouth. Easier to fill by hand, and the liner can be swapped without changing the bag. |
| Inside laminated bag | Fabric laminated on the inside only, closing the weave without an outer film. Cheaper than a full BOPP bag and still sift-proof. |
| Kraft paper liner | A paper inner ply for products where paper contact is preferred, or where the pack must feel paper based. |
| Aluminium foil laminate | Where a real moisture, oxygen or aroma barrier is needed — dairy powders, coffee, dehydrated ingredients. |
| Micro-perforated liner | For products that must release moisture rather than trap it — fresh produce, some seeds and feed. |
Choosing a liner
- Fine powder that sifts through the weave — inside laminated fabric, or a sewn-in PE liner.
- Moisture sensitive product — PE liner at minimum; aluminium foil laminate for a real barrier.
- Product that must breathe — no liner, or a micro-perforated one. Sealing fresh produce in a PE liner is how you create mould.
- Food contact — food grade PE or food grade kraft liner with the appropriate declaration.
- Valve filled bags — the liner has to suit the filling nozzle; we specify it against your equipment.
FAQ
Will a PE liner keep my product dry in a sea container?
A PE liner significantly reduces moisture transfer but it is not absolute. In humid trades or long transit, the answer is usually a thicker liner plus desiccant, or an aluminium laminate for a genuine barrier. Tell us the product, the route and the transit time and we will recommend accordingly.
Can the liner be recycled with the bag?
Not always — a PE liner inside a PP bag is a mixed structure. If end of life recyclability matters in your market, talk to us about mono-material options and about whether an inside laminated bag would meet your barrier requirement without a separate liner.
Does adding a liner change the bag size?
It does. A sewn-in liner takes up space inside the bag, so we increase the bag dimensions slightly to keep your filled weight and shape the same. This is one reason we always quote from the product and fill weight rather than from a stock size list.
Sending fine powder or moisture sensitive goods?
Tell us the product, the packing weight and the destination. We will specify the liner that protects it without over-engineering the cost.
- Emailsales@unisunpack.com
- Tel / WhatsApp+86 15825665852
- FactoryWenzhou, Zhejiang Province, China 325000
- Response timeWithin 24 hours, Monday to Saturday
