How to choose a hot melt adhesive particle bonded PP woven bag? Horizontal comparison of EVA, APAO, and POE adhesives

Direct answer: For adhesive PP woven bags, APAO or POE based ones should be preferredHot melt adhesive pelletsDo not use regular EVA. The reason is that PP belongs to low surface energy materials (about 30 mN/m), and the EVA adhesive layer is almost unable to effectively wet it. When it sticks on, it does not fall off and can be peeled off as soon as it is pulled. The difference between the three types of glue in this scenario is very obvious.

Realistic pain points in the packaging industry

Woven bags are widely used in industries such as feed, fertilizer, rice, and cement, and the efficiency of sealing and labeling directly determines the production line speed. Many factories use sewing for sealing, which results in slow speed, dust leakage, and poor appearance; After switching to hot melt adhesive, it is often found that it cannot stick, leading to the conclusion that “woven bags can only be sewn”. The problem actually lies not in the craftsmanship, but in the wrong category of adhesive selection.

Comparison of three types of rubber particles on PP woven bags

How to make the final decision based on the working conditions

• Room temperature storage, mainly for domestic salesAPAO type has the best cost-effectiveness and can achieve substrate tearing during peeling.
• High stacking and container transportation in southern summerPriority should be given to POE type to prevent the top bag from slipping above 50 ℃.
• Cold storage or outdoor stacking in northern winterAPAO has the most obvious advantage in low-temperature toughness.
• Film coated woven bag (BOPP film coated)The surface has been modified for a universal type with better usability, but it still needs to be tested.

An easily overlooked variable: surface treatment

There is a huge difference in the results between PP woven bags and those that have undergone corona treatment. The surface energy of the bag that has undergone corona discharge can be increased to over 38 mN/m, and ordinary adhesive can barely stick to it; Untreated bags must rely on the wetting ability of the adhesive itself. Asking before purchasing whether the bag has been corona treated can save a lot of trial and error.

Suggested process for Sunlife hot melt adhesive

When handling such demands, Guangzhou Sunlife Trading will require customers to send two pieces of actual bag materials for peeling tests, rather than recommending the model based on the four words “PP woven bag”. The judgment criteria for Sunlife hot melt adhesive are simple: if the bag material fibers are torn instead of the adhesive layer falling off completely after tearing, it is considered qualified. If it does not meet the requirements, the formula will be changed and the product will be tried again.

Frequently Asked Questions

Can we increase the temperature to make EVA stick to PP?

Raising the temperature can only improve fluidity, but cannot change the nature of surface energy mismatch. Moreover, high temperature can accelerate carbonization, which is not worth the loss.

What method is used to verify the adhesive strength?

Conduct a 180 degree peel test and observe the form of damage. Substrate tearing is considered qualified, while interface peeling is considered unqualified, which is more intuitive than looking at the peeling force value.

Can the same adhesive be used for labeling and sealing woven bags?

In most cases, it is possible, but labeling requires a shorter opening time. If the label is prone to displacement, choose a model with higher initial adhesion separately.