Innovative packaging solutions since 1992

WOVEN POLY BAGS

Excellent Strength Properties, Improved Tear Resistance, and Breathability

Material Motion provides a wide variety of Woven polypropylene (WPP) bags that are used across many industries, including agriculture, construction, food ingredients, animal nutrition, chemical, mining & minerals. Designed and manufactured from durable, lightweight woven polypropylene tapes, WPP bags offer excellent strength properties, improved tear resistance, breathability and added moisture protection when laminated.

They are a cost-effective packaging choice making them ideal for storing and transporting a wide assortment of dry flowable goods. Material Motion can provide an assortment of fabric colors, sizes and styles to meet all of your requirements and can print bags with up to 8 individual colors. They are a sustainable packaging option since they are fully recyclable and can be collected, washed, shredded and pelletized for use in other plastic products. We have a global network of manufacturing partners and also offer WPP bags proudly Made in the USA.

Offered in a wide array of designs and styles, Material Motion’s Woven Polypropylene bags can be customized to meet your specific needs. These bags have higher tensile strength, offer better moisture and oxygen barrier properties, when laminated, and are more impact resistant than paper bags.

Bag Styles:

Sewn Open Mouth (SOM)
Valve Bags

Features and Benefits:

Woven PP fabric weave options – 5 x 5, 8 x 8, 10 x 10
Multiple fabric colors – White, Green, Yellow, Blue, Orange with or without transparent/clear fabric gussets
Laminated fabric available
Tubular fabric up to 45” wide
Increased strength and durability
High impact resistance
Improved moisture resistance (MVTR) when laminated
High quality Flexographic printing up to 8 colors
Fully recyclable material
EZ Open Pull Tape
Custom Handles available
Imported bags – Leadtime 12-16 weeks
Bags Made in the USA – Leadtime 2 to 3 weeks
- smaller orders available with custom print capabilities up to 6 colors

Kraft Paper Laminated PP Bag Construction – Paper / Poly Bags

Kraft paper laminated polypropylene bags are a hybrid construction, combining a woven plastic fabric with an outer paper layer. Essentially, these bags combine the strength of plastic with the printability and feel of paper.

Key structural features of this composite design include:

Woven PP Core

The backbone of a kraft laminated PP bag is a woven polypropylene fabric. Polypropylene strips (called tapes) are extruded from PP resin, stretched for strength, and woven into a fabric much like weaving textile threads. This woven PP fabric is what gives the bag its exceptional tensile strength and tear resistance. It looks like a mesh or weave of plastic threads if viewed closely. Typically, the weaving is tight (i.e. 8 x 8 or 10×10) tapes per sq. inch to provide a solid structural net. This woven layer can bear heavy loads and resists punctures far beyond what paper alone can handle. It’s the same material base used in standard woven PP sacks (like those white grain or rice bags common worldwide).

Paper Outer Layer (Lamination)

The woven PP core is laminated with a layer of kraft paper on one side (usually the outside of the bag). Lamination is achieved by bonding the paper to the plastic fabric using a thin layer of molten polymer. In manufacturing, this is often done by extrusion coating: a thin film of polyethylene (PE) or polypropylene is extruded and acts like a glue between the Kraft paper and the PP weave. Once cooled and pressed, the result is a single composite material: paper on the outside, plastic woven on the inside. The kraft paper used for lamination is often in the range of 60–80 gsm – sturdy enough to add some stiffness and take print well, but not too thick as to make the bag unwieldy. The paper can be brown or white, depending on printing needs and aesthetic. After lamination, the paper and fabric move as one unit, so converting (cutting, folding) can be done similarly to other sack materials.

Hybrid Wall Structure

Effectively, a kraft laminated PP bag can be thought of as a two-layer structure (not counting the bonding resin): one layer of paper, one of woven PP. In some designs there may also be a very thin internal coating on the inner surface of the woven PP to improve moisture barrier or to make the inside smoother (important for certain products so they flow out easily). But generally, the structure isn’t “multiwall” in the traditional sense – it’s a single-wall composite. However, because the inner layer is woven plastic, it behaves differently than a simple single-layer paper bag; it’s far stronger and less prone to tearing.

Bag Conversion (Cutting & Sewing)

Once you have the laminated roll, the bag is formed similarly to other woven sacks. Usually, these bags are made as open-mouth sacks: the laminated material is cut to size, a tube is formed (with the paper side out), and then one end is folded and stitched shut. The stitching often goes through the laminated material; a strip of protective fabric or paper may be applied over the stitches for reinforcement. The top is left open for filling and will be sewn orotherwise sealed after filling. It’s also possible to create block-bottom paper-poly bags – newer machinery (including some Starlinger lines) can fold and glue the bottoms of woven bags to make a square-end sack much like a paper valve bag. In such cases, even valve openings can be added, giving a valve sack made of PP and paper composite. This is a more advanced configuration used for things like cement in some markets, where the bag has the brick shape of a paper cement bag but is a laminated woven sack.

Reinforcements and Features

Paper-laminated PP bags can also incorporate additional features. For example, micro-perforations can be added through the paper and fabric if the product inside needs to “breathe” (to let air escape during filling, which is common for fine powders). Handles can be die-cut into paper and fabric for smaller consumer-oriented sacks. The lamination process itself seals the outer surface, but if needed, an inner PE liner can still be inserted for extreme moisture-sensitive products (though often not necessary as the woven fabric plus lamination already provide substantial water resistance). The outer paper gives a somewhat rigid structure, so these bags hold their shape well when filled.

In summary, a Kraft paper laminated PP bag is built by fusing paper onto a plastic skeleton. It’s a composite wall – paper for printability and surface, polypropylene fabric for the muscle. This design results in a bag that looks and feels like a paper sack at first touch but has hidden reserves of strength and weather resistance courtesy of its PP core.

Industries Served:

Food Ingredients, Pet foods, Animal Nutrition, Bird Seed, Cat Litter, Grass Seed, Fertilizers, Pesticides, Polymer & Resins, Concrete, and Construction Materials.

ADDITIONAL WOVEN POLY BAGS RESOURCES

The Three Most Common Retail BOPP Bag Styles