It started in Germany and it is expected to spread in other country depending on the capacity of new diaper manufacturer.

Drylock Technologyes is the new venture of a long-time private label hygiene executive Bart Van Malderen that is getting back into European diaper markets. The biggest distinctive feature of this venture is that diapers they are going to produce will be the first fully fluffless diaper ever (at least for EU market). And they will be the only alternative to DryMax technology from Pampers that introduced a couple of years ago the almost fluffless diaper core. In fact Pampers contains a small amount of fluff (so called curly fibers) in the product altough its main function is to acquire and distribute liquid and not to absorb it.

Core is made of super absorbent polymer encapsulated between 2 layers. The distinctive feature is that SAP is contained in small pockets formed by combination of two layers and are kept in place without (or with a very low amount) additional thermoplastic material but only by means of bonds all over the 2 webs. These bonds are designed to allow controlled and gradual loosening when SAP swallow and expand. This design provide space for SAP volume growth and avoid reduction of SAP performances because of consequent pressure increase after swallowing. More liquid is absorbed and more bonds are broken releasing more space.

The new diaper is made of a new fluffless core consisting of SAP in larger quantity than standard diaper. In order to avoid gel blocking phenomena Drylock uses a very thick acquisition layer (around 150 gsm) that grant some softness to the product. This gives to the product a very thin profile and possibility to claim a great saving in shelf space and transport cost. Additionally it provides great benefit to the user because it fits perfectly as an underwear.

Technology used to produce this core is not so innovative because it is derived by printing process. But it is the first time it is used in diaper manufacturing. It should consists of a drum with a clustering means, an injection nozzle to provide SAP into perforated side of previous means and a system to transport carrier web in a position to properly receive SAP. More info  in the coming days. Stay tuned. 

 

2.- diaper with narrow and straight central chassis with elasticated side panels in the front and in the back. This is a concept introduced by P&G and KCC and it is greatly widespread in US and EU. 

3.- Diaper with refastenable closure system on the side panels. Mainly present in US. 

Janus eliminates the need of side seam to connect the front and back portion of the pant-diaper and therefore simplify significantly the whole production process. The innovation consists of new product design with lateral elasticated panels with a mechanical closure system to connect each other. Even though this product configuration is not totally new the method to manufacture such product gives some advantage eliminating a lot of bottle necks in these type of processes. 

Our recommendation is to design an HB core.

Good products have core with a tridimensional shape. It means that a core with uncompressed fluff show a tipical increased thickness (it means more absorbent material) in the crotch area and especially in the front side. See simplified core design on the right. You can see there is a first layer along the whole core and a second one positioned in the center/front area. These two layers can be two distinct cores but generally it is a single core with a 3D profile (usually it is obtained through a profiled mould filled by absorbent material).

You can identify 3 different zones

        * shallow zone:    it is the lightest area mainly teh back of the core

        * deep zone:    it is the heaviest area and it is located where you need more absorbency

        * transition zone:    it is the area between shallow and deep

Typical basis weights vary from 100 to 200 for shallow zone and fro 400 to 700 for deep zone. As you can easily understand depending on what deep zone shape and basis weights you choose for your core you will have a specific distribution of absorbent capacity from front to back. Pic shows a graph of capacity profile for a specific product obtained through a xls software developed by iResolve named PocketShape

Since we choosed to design an HB core it means SAP will follow fluff distribution (if our equipment is able to do it!!). More SAP we add more absorbent capacity you have distributed along the core with same “capacity diagram” that fluff defined.

A simple spreadsheet like PocketShape will help you to obtain the proper “capacity diagram” and modify your core geometry accordingly.

Of corse you can design a more stylish cores, rounded and narrow at crotch area  but the basic rules we have described here above are the same.

Just their application requires more sophisticated tools to predict core performances.

These SAPs are superior to fluff in their ability to absorb large volumes of aqueous body fluids, such as urine (i.e., at least about 15 g/g), thus making smaller, thinner absorbent structures feasible. In addition SAP particles typically pack closer than fibrous structures, thus achieving even thinner cores at elevated concentrations.

These SAPs are often made by initially polymerizing unsaturated carboxylic acids or derivatives thereof, such as acrylic acid, alkali metal (e.g., sodium and/or potassium) or ammonium salts of acrylic acid, alkyl acrylates, and the like. These polymers are rendered water-insoluble, yet water-swellable, by slightly cross-linking the carboxyl group-containing polymer chains with conventional di- or poly-functional monomer materials, such as N, N'-methylene-bisacryl-amide, trimethylol-propane-triacrylate or triallyl-amine. These slightly cross-linked absorbent polymers still comprise a multiplicity of anionic (charged) carboxyl groups attached to the polymer backbone. It is these charged carboxyl groups that enable the polymer to absorb body fluids as the result of osmotic forces, thus forming hydrogels.

The degree of cross-linking determines not only the water-insolubility of these SAPs, but is also an important factor in establishing two other characteristics of these polymers: their absorbent capacity and gel strength.

Absorbent capacity or "gel volume" is a measure of the amount of water or body fluid that a given amount of SAPs will absorb. Gel strength relates to the tendency of the SAPs to deform or "flow" under an applied stress. SAPs useful as absorbents in absorbent structures and articles such as disposable diapers need to have adequately high gel volume, as well as adequately high gel strength. Gel volume needs to be sufficiently high to enable the SAP to absorb significant amounts of the aqueous body fluids encountered during use of the absorbent article. Gel strength needs to be such that the SAP formed does not deform and fill to an unacceptable degree the capillary void spaces in the absorbent structure or article, thereby inhibiting the absorbent capacity of the structure/article, as well as the fluid distribution throughout the structure/article.

Prior absorbent structures have generally comprised relatively low amounts (e.g., less than about 50 % by weight) of these SAPs. There are several reasons for this. The SAPs employed in prior absorbent structures have generally not had an absorption rate that would allow them to quickly absorb body fluids, especially in "gush" situations. This has necessitated the inclusion of fibers, typically wood pulp fibers, to serve as temporary reservoirs to hold the discharged fluids until absorbed by the SAP.

More importantly, many of the known SAPs exhibited gel blocking.

"Gel blocking" occurs when particles of the SAP are wetted and the particles swell so as to inhibit fluid transmission to other regions of the absorbent structure. Wetting of these other regions of the absorbent member therefore takes place via a very slow diffusion process. In practical terms, this means acquisition of fluids by the absorbent structure is much slower than the rate at which fluids are discharged, especially in gush situations. Leakage from the absorbent article can take place well before the particles of SAP in the absorbent member are even close to being fully saturated or before the fluid can diffuse or wick past the "blocking" particles into the rest of the absorbent member. Gel blocking can be a particularly acute problem if the particles of SAP do not have adequate gel strength and deform or spread under stress once the particles swell with absorbed fluid.

This gel blocking phenomena has typically necessitated the use of a fibrous matrix in which are dispersed the particles of SAP. This fibrous matrix keeps the particles of SAP separated from one another. This fibrous matrix also provides a capillary structure that allows fluid to reach the SAP located in regions remote from the initial fluid discharge point. However, dispersing the SAP in a fibrous matrix at relatively low concentrations in order to minimize or avoid gel blocking can lower the overall fluid storage capacity of thinner absorbent structures. Usage of lower concentrations of these SAPs limits somewhat the real advantage of these materials, namely their ability to absorb and retain large quantities of body fluids per given volume.

Another reason why extremely high concentrations of SAP were not possible resides in the physical integrity disadvantage of structures made of particulate material. Creating a fibrous matrix therefore also had the advantage of providing a fiber re-enforced structure, similar to those used in many other technical situations where structural re-enforcement is provided by fibrous elements, such as in fiberglass. 

Besides increasing gel strength, other physical and chemical characteristics of these SAPs have been manipulated to improve their performance especially to decrease gel blocking.

This product is quite new because absorbent core is made of 2 nonwovens wrapped around a mix of SAP. SAP is kept in position witout use of any fluff but only with a special glue. This system allow to place SAP only where it is needed (and you will see there is no SAP in the back) and of course to save a lot of fluff.

In a size 5 in US you will find about 14g of SAP (and positioning glue). In this way the same absorbency of previous product version is guaranteed.

As we have stated at the beginning it is not completely true it is fluffless because the acqusition layer is still made of fluff. As the previos product there is a patch consisting of a web (usually a resin bonded material) and a layer of curly fibers without any SAP. This is a design very peculiar and it is needed to give to consumers the feeling of a (altough very little) thickness. A completely fluffless core with a very thin product could cause some complaints from the market. Anyhow this design allow to keep the same structure of previous product in contact with the skin of babies. It should reduce possibilities to generate negatives (eg rushes) because hte product is more or less the same.

Here you will find some drawings showing the Pampers Cruiser structure obtained throug a reverse engineering approach.

More detailed info are available.