PP(polypropylene) Block bottom valve bag types

PP Block bottom packaging bags are roughly divided into two types: open bag and valve bag.

At present, multi-purpose open-mouth bags are widely used. They have the advantages of the square bottom, beautiful appearance, and convenient connection of various packaging machines.

Regarding the valve sacks, it has many advantages such as cleanliness, safety, and high efficiency when packaging powders.

In principle, the open-mouth bag is fully opened on the top of the bag when packaging, and the packaged powder falls from the top to fill it. The valve bag has an insertion port with a valve port at the upper corner of the bag, and the filling nozzle is inserted into the valve port for filling during packaging. The filling process reaches a sealed state.

When the valve bag is used for packaging, only one packaging machine can basically complete the packaging work, without the use of additional processes or sewing machines for sewing. And it has the characteristics of small bags but high filling efficiency, good sealing, and environmental protection.

block bottom open bag block bottom bag


1.Types of valve pockets and sealing methods:

Regular internal valve bag

Common internal valve bag, the general term for the valve port in the bag. After packaging, the packaged powder pushes the valve port outward so that the valve port is squeezed and closed tightly. Play the role of preventing powder leakage. In other words, the inner valve port type valve bag is a packaging bag that can prevent the powder from leaking as long as the powder is filled in.

Extended internal valve bag

Based on the regular internal valve bag, the valve length is a bit longer which mainly used for heat sealing for one more secure lock.

Pocket valve bag

The valve bag with a tube (used when filling powder) on the bag is called a pocket valve bag. After filling, the outer valve bag can be sealed by folding the tube and stuffing it into the bag without glue. As long as the folding operation can achieve a sealing degree that will not cause problems in actual use. Therefore, this kind of bag is widely used for manual filling. If there is a need for further complete sealing, a heating plate can also be used for complete sealing.

2.Types of inner valve materials:

To respect different industry packaging requirements, the valve materials can be customized like in non-woven fabric, craft paper or other materials.

Kraft paper bag

The widely used raw material for powder packaging bags is paper. According to cost, strength, ease of use or handling, etc., the packaging bags constitute various standards.

The number of layers of kraft paper generally varies from one layer to six layers according to the application, and coating or PE plastic / PP woven fabric can be inserted in for special requirements.

Kraft paper bag with polyethylene film

The structure of the bag is a layer of polyethylene film sandwiched between kraft paper. Its specialty is that it has high moisture resistance and is suitable for packaging powders whose quality can deteriorate as long as they come in contact with air.

Inner coated kraft paper bag

The innermost layer of kraft paper is coated with a plastic coating to form a kraft paper bag. Because the packaged powder does not touch the paper bag, it is hygienic and has high moisture resistance and airtightness.

PP woven fabric combined bag

The bags are stacked in the order of PP woven layer, paper, and film from outside to inside. It is suitable for export and other places that require high packaging strength.

Kraft paper bag + polyethylene film with micro-perforation

Because the polyethylene film is pierced with holes, it can maintain a certain degree of moisture-proof effect and make the air escape from the bag. Cement generally uses this type of internal valve pocket.

PE bag

Commonly known as the weight bag, it is made of polyethylene film, and the thickness of the film is generally between 8-20 microns.

Coated PP woven bag

A single layer PP woven bag. This is a new and innovative packaging technology, a bag made without adhesives from coated woven polypropylene (WPP) fabric. It exhibits high strength; is weather-resistant; withstands rough handling; is tear-resistant; has varying air-permeability; is recyclable and reusable.

Since it was made by the ADStar machine, people also call it an ADStar bag. It is superior to other comparable products as far as resistance to breakage is concerned, is versatile, and also eco-friendly and economical. For unique packaging requirements, the bag can be produced with UV Protection and with various colored woven fabrics.

Laminations are also an option, to give a gloss or special matt finish, with high-quality graphics & printing up to 7 colors, including process printing (photographic), i.e.: Laminated with BOPP (gloss or matt) film with high-quality photographic printing for the ultimate presentation.

3.Advantages of the PP woven block bottom bag:

Higher Strength

Compared to other industrial sacks, Block Bottom Bags are the strongest bags in polypropylene woven fabric. That makes it resistant to dropping, pressing, puncturing, and bending.

Worldwide cement, fertilizers, and other industries have observed a zero breakage rate by using our AD * Star bag, doing all stages, the filling, the storage, the loading, and transportation.

Maximum protection

Coated with a layer of lamination, Block Bottom Bags keep your goods intact till they are delivered to the customer. Including the perfect shape and intact content.

Efficient stacking

Due to the perfect rectangular shape, Block Bottom Bags can be stacked high using space efficiently. And can be used in both manual & automatic loaders.

Fits perfectly with palletizing or truck loading equipment, as it is the same size as other sacks made from different materials.

Business benefits

Block Bottom Bags fits perfectly with palletizing or directly in trucks. So its transportation becomes very easy.

Packed goods will reach the end customers in perfect condition so it will give the factory more trust and market share.

No Spillage

Block Bottom Bags are perforated with a star micro-perforation system that allows air to come out holding the cement or other material without allowing any seepage.

More Market Value through more printing surface

Block Bottom bags takes a box-type shape after filling thus offers more printing surfaces on the bag through Top & Bottom Flat which can be read from the sides when the bags are stacked.

This increases visibility for the customers and adds to the brand image and better market value.

Resists water & humidity

High humidity and rough handling are easily tolerated by Block Bottom bags. So they arrive without any broken at the customer warehouse, resulting in utmost customer satisfaction.

Environment Friendly

Block Bottom bags are Fully Recyclable.

It has welded ends and no toxic glue is ever used, hence avoiding any pollution.

Block Bottom bags are required in low weight compared to other bags, so we can save raw material.

The low failure rate and breakage become an important economic factor and a big environmental benefit.

Bag size and valve size

Even if the same material and the same layer are used, the size of the packaging bag and the valve are very different. The size of the valve pocket is calculated using the length (L), width (W), and flattened diameter (D) of the valve port as shown on the right. Although the capacity of the bag is roughly determined by the length and width, the important thing when filling is the flattened diameter of the valve port. This is because most of the filling nozzle size is limited by the flattening diameter of the valve port. When selecting a bag, the valve port size of the bag must match the filling port size. And one more important thing is the air permission rate in case needed.

4.Bag application:

Block bottom bags are ideal for different sectors: building material like putty, gypsum; food products like rice, flour; chemical powder like food ingredient, Calcium carbonate, agricultural products like grains, seeds; resins, granules, carbon, fertilizers, minerals, etc.

And it is the best for packing concrete materials, cement.


Post time: May-29-2024