Core Design

Some of you asked me to give some hints to design a core for a diaper.
Here you are: below you can find some indications to start design your own diaper core. But stay tuned for additional info and tools to improve your nappy!!

A core is made of a mix of fluff and SAP. Usually this mix is “homogeneously blended” (HB): it means that SAP and fluff are in the same ratio everywhere along the core.

The reason to have an HB core is because SAP works better when it is well mixed with fluff and this improves core general performances. Of course other type of constructions are possible although, with current cores available on the market today, they do not reach performances that HB cores can. Therefore my recommendation is to design an HB core.

Good products have core with a three-dimensional shape. It means that a core with uncompressed fluff show a typical increased thickness (it means more absorbent material) in the crotch area and especially in the front side.

See simplified core design in Pic1 on the side.

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 the 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 are what you see in Pic1. As you can imagine depending on deep zone shape and basis weights you choose for your core you will have a specific distribution of absorbent capacity from front to back.

See Pic2 hereunder.

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 will help you to obtain the proper “capacity diagram” and modify your core geometry accordingly.

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

Just their application requires more sophisticated tools to predict core performances. We will see them in a next post.

Something more on Change 'N Go

After many requests I received during past weeks hereunder I will list some applications about reusable diapers and specifically about diapers with repleaceble cores.
These applications have some links with new baby diaper launched by Pampers named Change 'N Go (www.pamperschangengo.com).

At the beginning of baby diaper history generally it was used a simple textile piece of cotton for this type of articles. This could be washed and reused many times but with poor performance and bulky appearance. To improve it evolved in a disposable product using high absorbtion powder in the core that allowed a slimmer product.

Moreover other features were added to the same disposable product (elastic panel, mechanical closures, printed and very soft materials). It is today a product so sophisticated that is a pity to throw it away after a single use. Many producers have been looking a way to improve the effectiveness of single diaper and increase its life. At the beginning it was obtained simply by increasing total capacity of absorbtion for a single diaper. But very soon it was clear it was not a direction suitable for ever.

A simpler and effective way to extend diaper life was to use inserts or additional cores. Hereunder some applications are listed as example.

• WO199415563
• WO2002080834
• WO2005020852

Those inserts had a common characteristic, or at least it appears at first glance as such: the absorbent insert typically is removable only from interior. The overgarment must be removed from the wearer in order to remove the insert.

The great innovation Pamper Change 'N Go brings on the market is the following: from now on there will be no need to remove diaper from the wearer when the insert is needed to be changed.

A few applications, listed here, disclose a specific design

• WO2006108029
• WO2008030984
• WO2008059401

consisting of a pocket, a space between backsheet and topsheet, configured to receive an absobent insert therin. In the backsheet it is provided a slit to easily access to the pocket. Moreover it is provided a flap that is positionable in an open configuration and a closed position. When it is in closed position the flap covers the slit and inhibits contact between the diaper wearer and absorbent insert positioned in the pocket.

Stay tuned for the next issue...

SCA WIPO Application in May/June 2008

In May/June 2008 WIPO published at least 14 applications from SCA. Mainly they are related to 3 projects:

1.- Antibacteria/odor control systems
The first project seems very important for SCA these months because it is the subject for 6 out of 14 applications (almost 50% of their bi-monthly production!). Altough some of them are related to the same invention but applied to different products (diapers and wipes) it represents a clear direction for future developments and news on the market. Anyway it seems some applications could face some opposition in the future for conflicts with previous applications and maybe they will be modified to have a patent granted. Here is the related applications about antibacteria/odor control project:

• WO 2008/060210
• WO 2008/060209
• WO 2008/060200
• WO 2008/060199
• WO 2008/058565
• WO 2008/054268

All of them disclose a system to reduce odor or infection through the usage of specific substance as monovalent salt, probiotic bacterium/organic acid, peroxy compound. See the applications for further details.


2.- Elastic laminates for improved pant type diapers
Additional applications are related to a new elastic material applied to construction of pant diapers. This material consists of 3 layers (outers of creped nonwoven and inner of elastic film). The laminate is activated through an incremental stretching process. According to SCA this production system should improve the usual laminates that today are available on the market. The possibility to have a specific material to produce a strechable pant with additional feature and less expensive compared to products available on the market today is a key point for SCA to keep on growing in this market sector. Howewer will wait for the next steps in the patent granting process to see if the applications will be successfull.

• WO 2008/060205
• WO 2008/060204
• WO 2008/060194

3.- Improved brethable backsheets
Some applications are related to new materials to improve breathability. This is a more and more important characteristic to improve comfort of the wearer especially for adult pant diapers.Some brethable materials seem good in terms of porosity but usually at same time they are poor in preventing leakage of liquid. In these months SCA claims a new material for breathable backsheet solving the issue of leakage of liquid through porous material. This material consists of a polymeric material that can change volume in response to liquid contact, presence of ions, change of temperature and as such closing porous when receiving insults - WO 2008/069711 and WO 2008/069752.


Other applications are related to typical belted adult diaper (WO2008/055520) with a specific ratio between belt and chassis widths, sensing magnetic device to detect diaper status (WO 2008/076005) and latest a coating of thermoplastic polymer to improve hydrophobic property of web materials and improve performances of finished product (WO 2008/071202).

KCC WIPO Applications in May/June 2008

Let's see what KCC published in May/June 2008 as Internatonal Patents Applications. Some of them are really interesting but maybe it is too early to see something on the market that incorporates any of those. But maybe we could be wrong...

Many applications are related to sensors/devices that are included or embedded in diapers to detect something. Specifically those sensors could be real electronic devices or otherwise they can be a simple chemicalstrip. Anyway the final goal is to embed additional detecting/analisys feature in diapers. This feature could be very useful with babies but even with elder people that are not anymore cooperative to perform some urine analisys.

One application is related to a system to carry out quality check on diapers incorporating such a sensor.

Standard method using metal detector could be influenced by the metallic sensor and for this reason KCC propose new system: X-Ray machine.

WO 2008/075227
WO 2008/075217
WO 2008/072118
WO 2008/072116
WO 2008/065550
WO 2008/053390

Other applicatiosn are mainly related to define new systems to dispose of sanitary napkins and reduce odor of bodily fluids. Two systems are disclosed:

a.- using a pocket that is previously filled with substances acting as odor control
b.- using a release liner (to wrap the used sanitary napkin in) printed with a special ink with substances reducing odors

Other applications are related to pants design. One is related to an integral waistband for adult pants. It is interesting but seems already seen in other applications from Unicharm. A second application is more interesting and deal with a design of a body panel. This panel should helps wearer to break the pants, following specific lines of weakness positioned on the front of the pants and not on the side as usual,or adjust its size around torso after the pant is opened with specific reclosable tabs.

Other applications are related to raw materials (flushable film and elastic nonwoven)

Hereunder you will find the complete list of all applications published by WIPO in May/June 2008.

1. WO 2008/075229 - TREATMENT OF PERSONAL CARE PRODUCTS TO REDUCE LEAKAGE
2. WO 2008/075227 - METHOD AND DEVICE FOR DETECTING THE PRESENCE OF MULTIPLE INSULTS IN AN ABSORBENT ARTICLE
3. WO 2008/075218 - DEODORIZING CONTAINER THAT INCLUDES AN ANTHRAQUINONE INK
4. WO 2008/075217 - LATERAL FLOW ASSAY DEVICE AND ABSORBENT ARTICLE CONTAINING SAME
5. WO 2008/075215 - DEODORIZING CONTAINER THAT INCLUDES A MODIFIED NANOPARTICLE INK
6. WO 2008/072118 - ABSORBENT ARTICLES INCLUDING A BODY FLUID SIGNALING DEVICE
7. WO 2008/072116 - ARRAY OF ABSORBENT ARTICLES WITH INDICATORS
8. WO 2008/072115 - DEODORIZING RELEASE LINER FOR ABSORBENT ARTICLES
9. WO 2008/072114 - WATER-SENSITIVE BIODEGRADABLE FILM
10. WO 2008/072111 - METHOD OF MANUFACTURING PLEATED DISPOSABLE GARMENT
11. WO 2008/068646 - INTEGRAL WAISTBAND FOR A DISPOSABLE ABSORBENT ARTICLE, AN ARTICLE AND A METHOD OF FORMING SAID ARTICLE
12. WO 2008/065550 - PROCESS FOR CONTROLLING THE QUALITY OF AN ABSORBENT ARTICLE INCLUDING A WETNESS SENSING SYSTEM
13. WO 2008/062327 - NONWOVEN-FILM COMPOSITE WITH LATENT ELASTICITY
14. WO 2008/056278 - BODY PANEL FOR AN ADJUSTABLE PANT-LIKE DISPOSABLE UNDERGARMENT AND THE UNDERGARMENT ITSELF
15. WO 2008/053390 - ABSORBENT ARTICLE CONTAINING LATERAL FLOW ASSAY DEVICE

P&G WIPO Applications in May/June 2008

In May/June 2008 P&G published a few Internatonal Patents Applications. Let's see what they are dealing with

The most interesting application is related to the usage of a replaceable core in a training pant (WO 2008/050309). This document is an extension of previous applications already published in the past months. This time what it is involved in the application is the method for using the diaper (and the changeable core) to selectively enable or disable the wetness indicator. Anyway it is interesting to know that P&G is working on this type of construction and maybe we will see soon something similar on the market.

Another application of interest could be the WO2008/050275 related to a new construction of closing system. We all know how it is easy to damage hooks of mechanical closures during conversion process. This application covers a design to fold properly a MF tab avoiding risk of pop open.

It worth a mention the application WO2008/056315 where it is claimed type of graphics to be applied to training pants to let them look more real pants alike. Good idea but it seems facing some conflicts with other previous applications

Then we find an interesting application on individually wrapping of sanitary napkins (WO 2008/075290). The aim is to reduce the thickness of wrapping film and avoid damages during the process (eg hot melt application). The result is pretty interesting, howewer the relevant search report shows some conflicts with previous applications.

The last application I would like to highlight this time is the WO2008/056315. Here it is described a method to manufacture a diaper with changeable core replaceble from outside "on the fly". It will be one of the applications to deal with when somebody else decide to follow P&G on this field especially converting machinery manufacturer

Hereunder you will find a list of all International Patent Application published under the PCT by Procter & Gamble in May/June 2008

1. WO 2008/075290 - INDIVIDUALLY PACKAGED DISPOSABLE ABSORBENT ARTICLE
2. WO 2008/070131 - ABSORBENT ARTICLES COMPRISING GRAPHICS
3. WO2008/065627 - DISPOSABLE ABSORBENT ARTICLES HAVING AN INTERIOR DESIGN SIGNAL
4. WO2008/062362 - WRAPPER HAVING A PREDETERMINED LINE OF WEAKNESS
5. WO2008/059461 - DISPOSABLE ABSORBENT ARTICLE HAVING A WRAP AND TUCK CONFIGURATION
6. WO2008/059403 - ABSORBENT ARTICLES WITH REPLACEABLE CORE COMPONENT HAVING FLUID PARTITIONING CHARACTERISTICS AND METHOD FOR EVALUATING SUCH CHARACTERISTICS
7. WO2008/059402 - METHOD FOR MAKING A REUSABLE DISPOSABLE ARTICLE HAVING A REPLACEABLE ABSORBENT INSERT
8. WO2008/059401 - ABSORBENT ARTICLES WITH REPLACEABLE CORE COMPONENTS HAVING STIFFNESS CHARACTERISTICS AND METHOD FOR EVALUATING SUCH CHARACTERISTICS
9. WO2008/056315 - DISPOSABLE PULL-ON ABSORBENT ARTICLE COMPRISING AN OUTERGARMENT-LIKE GRAPHIC
10. WO2008/053456 - ABSORBENT ARTICLE WITH HANDLES OF SLOW RECOVERY MATERIAL
11. WO2008/053453 - ARTICLE WITH SECONDARY FASTENING SYSTEM
12. WO2008050310 - METHOD FOR USING A DISPOSABLE ABSORBENT ARTICLE AS A SWIM PANT
13. WO2008/050309 - METHOD FOR USING A DISPOSABLE ABSORBENT ARTICLE AS TRAINING PANT
14. WO2008/050275 - RELEASE TAPE-FREE FASTENERS AND DISPOSABLE ABSORBENT ARTICLES UTILIZING THE SAME

New reusable diaper from P&G

Pampers introduced a new baby diapers in US. For the time being it seems it is available just if ordered on line but we are waiting for some other news in the next weeks (available in store?)
This diaper is very innovative because it introduce a new structure design to include additional functionalities to the standard product.

It is named Change 'N Go and consists of a baby diaper having a replaceble absorbent core. This can be replaced "on the fly" while baby is wearing the diaper. More info and video can be obtained at http://www.pamperschangengo.com/

I am pretty sure we will see many patents applications on this subject coming up in the next months from many diaper producers in order to be prepared and not to loose positions in this possible niche market.

In the meantime I can highlight a first patent application on "reusable diaper" related to this product describing all news. It is the WO2008/059402 and it claims the innovative construction based on chassis with an opening window to slip in and out absorbent cores without removing the diaper from the baby.

Other patents available are related to stiffness of absorbent core (it is important to guarantee functionality to the product and avoid folding during pad changes). See for example WO2008/059401.