The Back Page: Taking it back 64 years

Originally published in Paper, Film and Foil Converter in March 1957

Pouch Papers Keep Rolling to Greater Future

For packaging high-volume, mass distributed items economically, pouch materials are hard to beat. Close teamwork between converter, customer and package machine maker is essential to production of better packages and this expanding and increasingly diversified market.

A greater swing in pouch packaging may be expected in coming months as large volume packagers seek to economize. 

Depending on the size, type, distribution and merchandising of the product to be packaged, and honest adaptability to machine handling, the pouch is inherently an economical flexible package. It eliminates separate production operations.  Beginning with base flexible materials in rolls, packaging machines form, fill and seal pouches (or packets as they are also called) automatically. The result is savings in time and labor to the product manufacturer. A further saving is realized in the cost of roll stock compared with converted bags or other packaging media. 

Aware of the trend to expanding pouch packaging, Thilmany Pulp and Paper Co. has developed a line of polyethylene-coated papers that meet a variety of packaging needs.

In airing the subject at a seminar for distributors, Thilmany reviewed the various types of pouches and the requirements of good pouch papers.

There are four basic styles of pouches, all of which can be produced by automatic machines. They are:

• THE PILLOW POUCH: This is most commonly used and was the first to be developed for automatic packaging. It is still widely employed for packaging free-flowing solids such as soap and coffee. It has a center seam seal plus a head seal at both ends and is formed from a single sheet. Although it has the advantage of a large capacity, its disadvantage as a paper pouch is a weaker center seam because the bond on one side is made to an uncoated surface. This disadvantage, plus operating difficulties (such as friction) in producing it, prompted manufacturers to develop other types.
• THE 4-SEAL POUCH Is the second most commonly used style and is formed by combining two sheets. Obviously, this eliminates the weak seen problem with pouch papers because the coated surfaces of each sheet can be bonded. Its advantage of extreme strength is offset to some extent by its capacity limitations, making it suitable for packaging small items. It can, however, be adapted to packaging shaped solids (screws, washers, etc.) by using a horizontal rather than a vertical feed, and by changing the sealing mechanisms to eliminate the reciprocating operation and thus reduce friction. Another desirable quality for some uses is that the pouches need not be cut apart individually, but can be used in “tandem” or “strip” with serrations between for later cutting or tearing by the consumer.
• THE 3-SEAL POUCH is fed into the machine from a single roll and is folded over and sealed on the three “open” sides. Not too common, its most popular acceptance is in small sugar packs for individual servings. Actually, it is a variation of the pillow pouch with the center seam problem eliminated, but with a much smaller capacity.
• THE 3-SEAL POUCH WITH GUSSET: One manufacturer researched an improvement in the 3-SEAL pouch and developed a style that is formed from a single sheet but provides a double gusset at the bottom. It's Advantage is that it provides greater capacity without the center seam sealing problem. This type has found wide acceptance in the food industry for packaging cake mixes, dry cream and similar products. The same manufacturer pioneered the development of an attachment which allows packaging in an inert atmosphere (gas packaging), prolonging the shelf life of products subject to rapid spoilage by eliminating oxygen from the package.

Pouch papers can be defined as any paper coated or treated with a heat sealable material, used in roll form, that is formed, filled and sealed in one operation on an automatic piece of equipment. The definition may also be applied to foil, cellophane, other films and combinations of these materials.

Heat seal ability is of prime importance to pouch papers. The bond is made by the single application of heat without other glues or adhesives to Siri. This is important in speeding production by eliminating drying time for adhesive to “set.”  Further, it eliminates handling and application of sealing material by the packager and may contribute to simplified machine design.

Thilmany features polyethylene coatings on its pouch papers which are distributed under the name of Polly-Kraft. In addition to polyethylene, other coatings can be applied for heat seal ability including nitrocellulose coatings, poly vinyls, Philofilm, specialized lacquers and waxes.

The paper company is coding most of its pouch papers with extruded polyethylene because the plastic rates so highly in a number of properties essential to good pouch packaging…

Relation to Machines

Converters who supply pouch papers to packagers should be aware of the minimum requirements necessary to produce a package from the standpoint of end product protection, shipping and merchandising. Also, they should be familiar with the type of machinery on which their rolls are to be run.

Briefly, pouch packaging machines operate on a reciprocating or non reciprocating principle. The first is a start and stop operation while the latter, once started, continuous without interruption.

This difference in machine operation may have a bearing on the type of material the converter suggests for packaging since:

Reciprocating machines usually require:

1. Higher tensile strength.
2. Better slip qualities of heat seal coating and paper.

Non-reciprocating machines can usually tolerant:

1. Lower tensile strength
2. Poorer slip qualities (or none) of heat seal coating and paper.

Another factor the converter must consider is pliability vs stiffness. These qualities can have a definite effect on machine operation and will vary from machine to machine. Some require pliability to form packages properly while others require stiffness to fill properly.

The type of heat seal is important. If the seal is face to face, the coated surfaces are brought together and fuse to each other, giving a very strong seal. Generally, and disregarding the protective requirements for the product, less heat seal material is required to give a satisfactory closure. 

If the closure is face to back, the heat seal material is in contact with an uncoated surface. This type of sealing may result in a weaker seam and normally requires more heat seal material. (It is understood that the former refers to coated pouch papers and not to films such as cellophane which are heat sealable in themselves.). *

*The full version of this article can be found in the March 1958 issue of Paper, Film and Foil Converter.