Tel:86-0750-6228802
Fax:86-0750-6228277
Mobile Phone:+8617718861990
Email:yingtong@yingtongpack.com
Address:Xinsha Industry, Muzhou Town, Xinhui District, Jiangmen, Guangdong Country Region China
Kraft bags (made from strong paper pulp, often unbleached or lightly bleached) are widely used for packaging in industries like food, cement, chemicals, fertilizers, feedstuff, etc. While kraft paper has good strength, it has limitations in moisture, gas, odor, light barrier, and sometimes grease protection. That’s where liners come in.
A liner is a material inserted or laminated inside the kraft bag structure to enhance performance. The liner helps protect the contents from external conditions, improves shelf life, maintains product quality, and can ensure compliance with regulatory or customer requirements.
Here are the most frequently used liner materials, what attributes they bring, and what trade-offs they involve.
| Liner material | Properties / Benefits | Common Use Cases | Drawbacks / Considerations |
|---|---|---|---|
| Polyethylene (PE) film | Excellent moisture barrier, flexible, food-grade options, low cost. HDPE or LDPE can be used depending on toughness needed. Provides reliable protection against water vapor and dust. | Food powders, cement, fertilizers, feed, resins, any moisture-sensitive goods. | Plastic adds to cost; may reduce recyclability if mixed layers are hard to separate; may need thicker PE or double layers for heavy or sharp materials. |
| Aluminum foil / foil composite | Blocks light, odor, gases; very strong barrier to moisture. Good for products sensitive to oxygen or that need protection from UV/light. | Coffee, tea, dried foods, certain chemicals or biotech materials, or any application needing strong barrier & shelf life. | More expensive; can affect flexibility; laminating and sealing must be well done; sometimes heavier; recycling can be more complicated. |
| Polylactic Acid (PLA) / Bio-based liners | Compostable, more eco-friendly; can offer moderate barrier properties, often used for “green” products. | Food items, boutique or ecological product lines; where branding or environmental credentials are important. | Generally weaker barrier than foil or thick PE; cost may be higher; heat sealing and processing may need care; compostability depends on local infrastructure. |
| Multi-layer films / Laminated liners | Combines different materials (e.g. PE + foil + polymer or PE + EVOH, etc.) to get a tailored set of barriers: moisture, gas, odor, light. The layering lets you balance cost vs. performance. | High-value food items; chemical/petrochemical powders; when long shelf life or extreme conditions (humidity, light, oxygen) are concerns. | More complex to manufacture; higher cost; sometimes heavier; may complicate recycling or disposal; sealing challenges. |
| Grease- or oil-resistant coatings (less common as full liner, more often as inner coating) | Protects against oil/grease penetration; helps with food packaging where fat content could degrade kraft paper. | Food packaging (snacks, fried items), grease-heavy substances. | May reduce breathability; coatings may need food-safe certification; may increase cost; may complicate recycling. |
When selecting liner material, you also have to consider:
Barrier Requirements: Moisture, oxygen, light, odor. What is the most critical for your product?
Durability: Is the product heavy, sharp, or abrasive? Will the bag be handled roughly?
Food Safety / Regulatory: If food or consumables, liner must be food-grade; whether foil-wrapped or plastic.
Environmental / Sustainability Goals: Compostability, recyclability, reducing plastic content; use of biodegradable or bio-based liners.
Printing & Branding: Some liners affect how well graphics show or how the bag can be printed.
Cost & Weight Trade-off: Heavier liners cost more and add weight; sometimes it’s better to over-engineer the kraft layers or use more plies rather than thick liner.
Looking at the product range from Yingtong (Guangdong Yingtong Paper Co., Ltd.), some of the kraft paper bag types already indicate liner usage:
Kraft Paper Bag with PE Liner — Yingtong offers 2-ply, 3-ply, 4-ply kraft paper bags with a PE liner inside.
valve bags, Cement Bags — These may need higher durability and moisture protection, so PE liners or multi-layer combinations are common.
This shows Yingtong has experience producing bags with different number of kraft layers plus PE liner to suit various industrial needs.
| Advantage | Disadvantage |
|---|---|
| Enhances product protection (moisture, light, oxygen, odor). | Increased cost, especially for high-barrier liners like foil or multi-layer composites. |
| Extends shelf life, reduces spoilage or product degradation. | Manufacturing complexity: sealing, lamination, layer adhesion, etc. |
| Allows use of kraft paper even for sensitive products. | Environmental concerns if non-recyclable layers are used; may reduce compostability or recycle value. |
| Flexibility in tailoring barrier vs cost trade-off. | Adds weight; may complicate shipping or handling; liner failures (leaks, perforations) can negate benefit. |
To pick the right liner for your kraft bag, follow a process like:
Define product vulnerabilities: Is moisture the main concern? Or oxygen? Light? Taste/odor migration?
Sketch usage scenario: Storage time, environment (humid vs dry), temperature, handling / transport severity.
Determine regulatory / safety requirements: Food safety, certifications, biodegradability, etc.
Estimate cost vs benefit: Over‐engineering costs more; is the extra protection needed?
Prototype and test: Try sample bags under real conditions to see barrier performance, durability, handling, etc.
If you work with Yingtong Packing, here’s how their OEM/ODM capabilities can support you:
Custom liner selection: You can request bags with specific liner materials (e.g. PE, foil, bio-based, multi-layer) matched to your product’s protection needs. Yingtong has product types like kraft paper bags with PE liner.
Multi-ply kraft structures: Yingtong offers 2-ply, 3-ply, 4-ply bag options with liner inside. Thicker kraft layers plus liner for heavy duty or industrial use.
Custom printing & design: If you need branding, graphics, or special finishes, OEM/ODM means you provide artwork/designs and Yingtong can integrate them.
Optimizing for sustainability: Yingtong can help balance liner type vs environmental goals — for example by using thin, food-grade PE rather than heavier foil if high barrier is not essential.
Full service: From material sourcing, prototyping, production, to packaging and shipping. Working with Yingtong allows control over specifications (liner type, kraft layer count, sealing, valve bags etc.) to get what you need rather than “off the shelf”.
Choosing the right liner material for kraft bags is a crucial decision that affects product protection, cost, sustainability, and customer satisfaction. Options range from simple PE liners, foil composites, bio-based materials, to multilayer laminates. Each option offers different trade-offs in terms of barrier performance, cost, environmental impact, and manufacturing complexity.
If you are sourcing kraft bags and want to ensure the liner inside meets your precise needs, partnering with a manufacturer like Yingtong Packing with strong OEM/ODM services gives you flexibility. You can tailor the kraft ply count, liner type, printing, and sealing to your product’s requirements, ensuring you get quality bags with the correct barrier and cost profile.
WhatsApp:
Phone:
Contact Now