Prill power: P&G files patent for dissolvable hair care pouches

Writing in its international patent​​, P&G said the water-soluble pouches were made from fibrous sheets and could contain one or several types of personal care pellets/prills that dissolved into a creamy product when in contact with hot water. Designed to fit in the palm of a user’s hand, the pouches had been designed to contain prill blends for shampooing and/or conditioning of the hair.

P&G said the invention offered a sustainable alternative to liquid shampoo and conditioner products that contained “significant bulk” ​with extra water, preservatives and stabilisers, but also an alternative to solid format alternatives that were often associated with poor usability. Many bars or prills, the company said, did not dissolve fast enough on impact with water and others melted during shipping or storage, ahead of reaching the consumer.

“As such, there remains a need for an easy to use, solid personal care article that has a melt point greater than 45​°C and rapidly disintegrates into a smooth, creamy, homogenous product upon hydration,”​ the company wrote in its patent filing.

The pros of solid hair care formats ​

P&G said there were “many advantages” ​to using a solid shampoo or conditioner product alternative versus traditional liquid, bottled compositions.

“For instance, solid personal care articles are less expensive to ship because solid articles can be substantially free of water, preservatives, and stabilisers. Furthermore, solid personal care articles can be easier to control the dosing and delivery of the product and in some instances, actives that are generally incompatible in a liquid composition can be stable in a solid article,”​ the company said.

“However, a drawback to solid articles is that they can take a long time to dissolve and users are impatient, especially when they are hydrating a solid article in their hands while in the shower, bath, or at a sink, where a relatively short period of time, for example 15-20 seconds, can feel like an eternity.”​

‘The pouch seems to dissolve instantaneously’​

In the current invention, P&G said the use of prills reduced this dissolution time significantly for consumers – to less than 10 strokes according to the Hand Dissolution Method which equated to around 5-10 seconds. Designing the prills into a ready-made, thermally sealed fibrous pouch also made using the product simpler for consumers, the company said.

“When the pouch is exposed to water, the fibrous sheet(s) and water-soluble prills quickly dissolve into a homogenous, uniform, smooth, creamy, liquid personal care composition, such as a shampoo or a creamy conditioner. In some instances, the pouch seems to dissolve instantaneously.”​

P&G said each pouch should contain enough prills to “sufficiently clean and/or condition a user’s hair”​ – anywhere between 0.5 – 5 grams. The prills could include both cationic surfactants and fatty alcohols along with a variety of active ingredients, the latter of which could also be incorporated into the fibrous element. Some pouch designs could also feature more than one internal compartment, P&G said.

Importantly, any prills used had to be formulated to be “water soluble, have a relatively high melting point, relatively fast dissolution rate, and dissolve to form a creamy and/or homogenous composition”. ​More specifically, the prills should have a melting point higher than 50°C.

P&G said the fibrous sheets making up the front and back of the pouch could be made from “a plurality of two or more fibrous elements” ​– inter-tangled or otherwise associated with one another to form a fibrous structure. The thermally sealed edging was made using a polymeric structurant like a starch.

WIPO International Patent No. WO/2022/027067​​
Published on: February 3, 2022. Filed on: July 30, 2021.
Title: “Water-soluble fibrous pouch containing prills for hair care”​
Inventor: Procter & Gamble – JE. Hilvert et al.