How to Increase Woven Sacks’ Strength Without Extra Cost?

Anyone who has ever used PP Woven Sacks understands the pain of receiving a pallet of perfectly packed sacks from the manufacturer to ship to their customer, only to have those bags tear on the way to the customer (i.e., loading, shipping, stacking). The loss is not just material; it also results in many rejections, complaints, and freight claims. What’s even more frustrating is that your GSM could have been correct, yet the PP Woven Sacks failed.

The reality is this: strength is not always a function of GSM. In many cases, modifications to the construction of PP Woven Sacks can increase their strength by 25-40% without increasing cost.

This is where Comsyn comes in. Comsyn is one of the largest and most technologically advanced manufacturers of PP Woven Sacks. They provide optimized production systems that create a stronger product than you are paying for today, without increased costs.

Why Do Woven Sacks Fail Even When GSM Looks Correct?

Even when a woven sack meets the specified weight, the manufacturer may have encountered internal engineering issues that significantly affect the bag’s strength. Here are some of the most common reasons that cause woven sacks to fail;

1. Loose or Irregular Weave

8×8 or 10×10 is an example of a low-mesh fabric with large spaces between the tapes. The gaps cause a decrease in;

• Tensile Strength
• Tear Resistance
• Bursting Strength

Even if the GSM (grams per square meter — a measurement of the density of the fabric) is higher, due to the loose weave, polypropylene (PP) woven sacks will be more vulnerable to damage by impact, dragging, or palletizing.

2. Wide, Low-Denier Tapes

A lot of suppliers choose to use low-denier (800-1000 denier) waiting tapes because they are bulkier. However, the “bulkiness” of the tape does not equal greater strength. Low-denier waiting tapes break very easily due to;

• Lower Molecular Orientation
• Poor Elongation Capacity
• Tape Edges (Tears) Open Up Upon Impact

By using narrow/high-denier waiting tapes, the overall strength of the woven sack is greatly increased without increasing the weight of the sack.

3. Poor Melt Flow Index (MFI) Control

Virgin polypropylene (PP) should be controlled with an MFI of approximately 3.0-3.8. When MFI is too high → it makes your tapes too brittle. When MFI is too low → it makes your tapes sticky and uneven. Having an incorrect MFI is one of the most common, unnoticed reasons why woven polypropylene sacks split open during handling.

4. Improperly dispersed filler or excessive filler.

Low-cost suppliers often include 10% or greater CaCO₃ as a way to save on production costs.

The impact of this is: weak areas in the tape, uneven distribution of the filler, reduced elongation, and poor resistance to impact.

The use of nano-dispersed CaCO₃ will fix the above issues, as well as significantly lower the overall cost.

5. Use of recycled materials in the critical layers of the tape.

When reprocessed PP is used to manufacture the tape, it degrades the overall quality significantly by reducing the tensile strength, elongation at break, and making the tape brittle. It also increases the likelihood of UV damage to the tape.

As food-grade woven sacks are a critical application, the use of 0% recycled material is mandatory.

How Much Stronger Can You Make a Sack Just by Changing the Weave Pattern?

Most customers overlook this, but the mesh pattern alone can change sack performance dramatically.

Mesh Count	Strength Gain vs 8×8	Benefits
8×8	Baseline	Cheapest but weakest
10×10	+10–15%	Slightly better weave
12×12	+25–35%	Best balance of strength + cost
14×14	+35–45%	High-performance sacks

Using a 12×12 mesh will produce an increase in softness, tensile, and tear strength of around 30% (when compared to 12×15 mesh) due to the resulting higher mesh count producing a more compact and better load distribution than the lower count.

For example, the transition from 12×15 to 12×12 for multiple types of bulk packaging (agriculture and cement) will be the simplest, easiest, and most cost-effective method of increasing the PP woven sack’s overall strength.

Which Tape Quality Parameters Actually Matter for Real-World Strength?

Better-Tape Products offers lower-weight tapes than its competitors because of the following characteristics.

Better Engineered Tapes Produce Greater Strength Than Heavier Tapes!

What Really Affects Performance:

1) High Molecular Weight Virgin Polypropylene (PP):

• Higher Elongation
• Better Orientation of Crystals
• Higher Load-Bearing Capacity

These are imperatives for all Woven Sack Manufacturers that utilize PP.

2) A Narrow Melt Flow Index (MFI) of 3.0 to 3.8

This is the optimum range for:

• Smooth Stretch of the Tape
• High Bonding Strength of Molecules
• Balance Between Stiffness and Flexibility

This is the most Important Indicator of the Performance of Tape.

3) Controlled level of Calcium Carbonate (CaCO₃) of less than 8% with Nano Dispersion (e.g., like microscopic dust particles)

By Nano Dispersion, we achieve:

• Greater Rigidity of Tape
• Higher Resistance to Impact; and
• Higher Resistance to Puncturing, without Increasing the GMS (i.e., Weight Per Square Meter of Film).

4) No Re-Processed Polypropylene (PP) Used to Manufacture Food Grade Sacks:

Food Customers want NO reprocessed resins in their Products due to the Following Reasons:

• Low Strength of Re-Processed Resins (PP)
• Contamination Risks; and
• Poor Sealing Properties.

Therefore, using ONLY Virgin PP gives us the Original Mechanical Properties with NO Compromises.

5) Uniformity of Tape Thickness +/-3%:

When Tape Varies in Thickness, one tape has to be Strong and One Weak; therefore, Uniformity of Tapes = Uniformity of Strength.

How Does Denier and Tape Width Affect Bursting Strength?

Conventional designs utilize 1000D wide tape for their strength; however, this tape is not flexible enough for use in the sack market.

Using 1200-1400D narrower tapes instead of 1000D tapes will increase the following:

• Maximum tensile load
• Elongation at break
• Impact absorption
• Bursting strength
• Without increasing the weight per square meter (GSM) of the tape.

By switching to narrower tapes between 1200-1400D, you can have a 20-30% increase in performance from just this change.

How Can UV Stabilization Be Improved Without Raising Cost?

When it comes to damage to outdoor storage bags, “UV Failure” is one of the main causes.

The solution?

Instead of adding a UV masterbatch only to the outer (skin) layer, you need to put the UV masterbatch into the middle (core) layer as well.

Benefits:

• UV life is increased by an average of 2x
• Degradation time is extended
• Heat resistance is greatly improved

When using the correct placement and a dosage of 2-3%, your overall lifespan will go from 600-800klY to 1200-1600klY at the same cost.

How to Reduce Coating Weight Yet Increase Lamination Strength?

Users often believe that having more coating equals more strength, which is not accurate. Strength is derived from the bond quality of the adhesive rather than the quantity of the coating.

By changing the corona treatment (at least 42 dynes), adhesive formulation, and melt coat distribution, it is possible to decrease the overall amount of coating used from 22 gsm to 16-18 gsm while actually increasing peel strength.

Doing this will lower your costs and provide you with better performance.

Comsyn – Engineered Strength You Don’t Pay Extra For

At Comsyn, stronger woven sacks aren’t considered to be a special feature; they will simply be what you will receive from the very start. They engineer performance through improved tapes, tighter woven patterns, accurate MFI control, and advanced Nano-Dispersion Technology to produce woven sacks that have high tensile-strength, high tear-strength, and high impact-strength while costing the same as the current production of your existing woven sacks. Therefore, you won’t pay any more for producing stronger packaging with Comsyn; rather, you will produce better and smarter.

Quick Checklist – 8 Zero-Cost Strength Boosters

To instantly upgrade your woven sacks (without increasing cost):

• Use 12×12 or 14×14 mesh
• Narrow tapes at 1200-1400 denier
• Select an MFi of 3.0-3.8
• Only use ≤8% CaCO₃ nanodispersed
• Corona treatment required ≥42 dynes
• Coating should be 16-18 gsm
• Place a UV masterbatch in the core
• Store rolls vertically and in a place where they won’t receive direct sunlight

Conclusion

It is essential to produce your products with more intelligent methods rather than spending additional money to get stronger bags. With proper selection of materials such as mesh characteristics and denier, MFI control, consistent tape, and UV treatment, bags can be manufactured to be 25% to 40% stronger than what is currently available, while still maintaining the same GSM and price as current products. Working with Comsyn, you can upgrade the quality of your woven sacks to be best-in-class engineered strength without any additional expense.

FAQs

• How can I determine whether my current supplier is using a 1300D tape rather than a 1000D tape?

Requesting a tape denier test report, a tensile test report for the tape used, or requesting a sample to be tested at Comsyn’s testing lab. The denier rating can be verified through standardized gravimetric analysis.

• Is it acceptable to reduce the coating weight from 22 gsm to 16 gsm when applied during monsoon months to protect food grains?

Yes — provided that the corona treatment reaches or exceeds 42 dynes and that adhesive bonding has been maximized. The final strength actually increases even with the lower coating weight.

• Can stronger bags handle high-speed cement valve-filling machines?

Yes — a tighter 12×12 mesh and 1300D is a great combination for providing increased bag mouth stability and bursting strength, which is required for valve-filling applications.

• Does stronger construction allow for more pallet stacking height?

Yes. Increased tensile strength, elongation, and bursting strength all contribute to improved pallet stacking stability, and can increase stacking stability by 10-25% depending upon product density.