The global demand for printed non woven bags is growing. Grocery brands, retail chains, and industrial distributors need these bags to carry the branding and products. As a company that produces these bags on a large-scale basis, choosing the printing method determines the cost-per-unit, color consistency, and production speed.
This guide discusses the different methods on how to print on non woven bags. It discusses right from selecting the substrate to choosing the right non woven fabric bag printing machine for your production needs.
What is a Non Woven Material?
A non woven material is a fabric that bonds polypropylene or PP fibers through heat, pressure, or chemical processes. The result is a porous, fibrous surface with low surface energy. This affects how ink bonds to the substrate or fabric.
The common weight range for each production is from 60 to 120 GSM. Each non-woven variant processes differently using a flexo press.
Below are examples of non-woven materials and how they are used in flexo printing:
- Spunbound PP: This substrate is widely used for reusable shopping and grocery bags. Its semi-smooth surface supports clean flexo ink transfer with minimal bleed. Most non woven bag printing lines start here.
- Spunbound-Meltblown-Spunbound or SMS: This three-layer laminate is used in industrial and medical-grade bags. Its denser surface requires a higher anilox cell volume to ensure adequate ink deposit.
- Laminated Non Woven or PP + PE Film: The polyethylene or PE layer creates a surface that is similar to flexible film. It accepts UV-curable inks well and supports high-detail, multi-color designs with sharper dot gain control.
- Stitchbond or Needle-Punched Non Woven: This non woven substrate has a coarser structure and is ideal for heavy-duty industrial packaging. It works best with large-format, lower line-screen flexo graphics where fine details are not required.
- Embossed Non Woven Polypropylene: This substrate is used in promotional and retail bags where a textured surface adds visual appeal. Softer flexo plates maintain ink contact across the raised pattern without smearing.
Proper machine setup prevents ink peeling and registration errors during high-speed production.
How to Print on Non Woven Bags
To ensure that the output matches the required quality, it is crucial to understand how to print on non woven polypropylene bags. The flexo press involves five process stages where operators must specifically calibrate for PP substrates.
Step 1: Preparing the Surface for Corona Treatment
Polypropylene has a surface energy of approximately 30 to 34 mN/m (millinewtons per meter) in its untreated state. Ink adhesion requires a minimum of 38 to 42 mN/m. What is corona pre-treatment increases the surface energy by shocking the fabric with electricity to help the ink stick. In this stage, operators verify the dyne levels with test inks before each production run.
Step 2: Selecting the Ink
Water-based inks are the standard for spunbound polypropylene and SMS substrates. These inks dry fast, have lower VOC emissions, and can meet EU food-safety standards (Regulation No 1935/2004) for safe packaging contact. UV-curable inks are ideal for laminated non-woven substrates where ink adhesion demands are higher, and a gloss finish is required.
Step 3: Configuring the Plate and Anilox
For spunbond PP, using a plate with Shore A hardness of 55 to 65 prevents ink squeeze-out on the fibrous surface. Anilox cell volumes of 6 to 10 cm³/m² ensure enough ink reaches the material without flooding the open fiber structure. Laminated non woven supports 150 to 200 lpi line screens for sharper graphics.
Step 4: Controlling the Tension and Registration
Non woven fabric stretches at a lower tension than Polyethylene (PE) or Polyethylene Terephthalate (PET) film. Servo-driven tension management at ±2 N (Newtons) prevents the fabric from stretching and causing color misregister. Without this, the tension drift on a 6-color job compounds and ruins the registration of fine overprint elements.
Step 5: The Drying System
Hot-air drying towers operating at 50 to 80°C between color stations cure water-based inks before the next unit prints. UV lamp systems (80 to 120 W/cm or Watts per cm) cure UV inks instantly. Inline drying is essential for non-woven fabrics because the porous surface slows troubleshooting flexo printing defects more than film.
How to Choose the Right Non Woven Fabric Bag Printing Machine
Choosing between a stack press and a CI press determines how your non woven fabric bag printing machine handles substrate variation and color count. This decision also impacts your total production length and efficiency.
Below is a guide on how to choose between the two printing machines:
Stack Type Flexo Presses
Stack-type flexo presses place each color station on an independent frame above or below the substrate path. This allows operators to set the independent tension per station. This setting is critical for heavier non woven substrates (90 to 120 GSM) that respond differently to nip pressure at each unit.
Stack flexo printing machine advantages work well for bag converters running mixed substrate lines: non woven in the morning, kraft paper in the afternoon. Changeover requires fewer adjustments when switching between different substrate weights.
Max. material width: 850mm, 1050mm, 1250mm, 1450mm
Max. printing width: 800mm, 1000mm, 1200mm, 1400mm
Printing length: 340−1000mm
Printing speed: 200m/min
CI (Central Impression) Flexographic Machines
Central Impression, or what is CI flexo press machines wrap the substrate around a single large central drum. This keeps all color stations in contact with one reference surface. This design delivers registration accuracy of ±0.1 mm across 6 to 8 colors. This is ideal for fine-detail logos and small text on printed non-woven bags.
CI presses suit high-volume operations printing spunbond PP or flexible packaging printing machines at 150 to 200 m/min. The central drum keeps stretchy materials stable, preventing the drift common in stack presses at high speeds.
Conclusion
Deciding on the correct method on how to print on non woven bags relies on choosing the right substrate type and machine configuration. Compatibility among the correct method, substrate type, and machine configuration ensures that your client’s non-woven bags represent their brand and serve their purpose.
RAZP’s stack and CI flexographic machines feature 100 mm-thick reinforced frames and servo-driven controls to ensure stability on challenging polypropylene materials.
RAZP operates as an ISO 9001:2015 certified manufacturer and a recognized National High-Tech Enterprise. With over 25 years of engineering expertise, we have delivered more than 500 machines to 15+ countries.