FIELD OF THE INVENTION

Process for making water soluble pouches containing a substrate treatment agent.

BACKGROUND OF THE INVENTION

Water soluble pouches for delivering substrate treatment agents, such as dishwashing detergents, laundry detergents, surface cleaning compositions, and laundry treatment compositions, are increasing in popularity globally. Typically, the consumer places the pouch in a compartment in the dishwashing machine or in the drum of a clothing washing machine or bucket of water, the pouch is exposed to water, and the pouch dissolves and releases the treatment agent.

The substrate treatment agent can be a solid or liquid. Some pouches have multiple compartments and liquids in each of the compartments. Some pouches have multiple compartments with one compartment containing a solid and another compartment containing a liquid. Individual compartments of multi-compartment pouches can have different dissolution rates, thereby providing for delivery of the substrate treatment agents within individual compartments at different times during the cycle of the wash.

Typically, marketers of pouches of substrate treatment agents sell a plurality of pouches within a single container. To promote ease of use and minimize waste, the pouches within a container are not individually packaged in secondary packages.

During manufacture and storage of the pouches in a consumer's home, the pouches can be exposed to small amounts of water and humidity. One example of how this can occur in a consumer's home is when the consumer reaches into a container of pouches to retrieve one for use. Her hand may be wet from washing dishes or pre-treating a clothing article. Water or other liquid may drip from her hand onto a pouch within the container. That pouch may sit in the container for weeks or months until it is used. This limited exposure to water or liquid can result in some amount of dissolution of the pouch which can cause a local weakness in the pouch. These local weaknesses can develop into leaks in the pouch during storage or pouches that rupture prematurely when placed in a washing machine or dishwasher.

With these limitations in mind, there is a continuing unaddressed need for water soluble pouches that can maintain their structural integrity during storage and not be prone to premature rupture during use.

SUMMARY OF THE INVENTION

A process of making a water soluble pouch comprising the steps of: providing a first mold (530) comprising a first cavity (570), wherein the first cavity comprises a first porous face (575); providing a water soluble first web (505) carried on the first mold; forming the water soluble first web to form a compartment (580) by applying a first pressure difference across the water soluble first web with the water soluble first web at a first maximum temperature and subsequently applying a second pressure difference across the water soluble first web, wherein the second pressure difference is greater than or equal to the first pressure difference; placing a substrate treatment agent (50) on the water soluble first web; providing a water soluble second web (565); and sealing the first web and the second web to one another to form an enclosed pouch (10) having a chamber (40) containing the substrate treatment agent.

The water soluble first web can be at a second maximum temperature when the second pressure difference is applied. The second maximum temperature can be greater than or equal to the first maximum temperature.

The first pressure difference can be applied by applying a first negative gage pressure to the first porous face and the second pressure difference can be applied by applying a second negative gage pressure to the first porous face, wherein the second negative gage pressure is less than or equal to the first negative gage pressure.

The step of forming the water soluble first web to form the compartment can be performed by thermoforming the water soluble first web to form the compartment.

The step of placing the substrate treatment agent on the water soluble first web can be performed by placing the substrate treatment agent in the compartment.

The process of making a water soluble pouch can further comprise the steps of: providing a second mold comprising a second cavity, wherein the second cavity comprises a second porous face; providing a water soluble third web carried on the second mold; forming the water soluble third web to form a second compartment by applying a third pressure difference across the second porous face with the water soluble third web at a temperature of from about 100° C. to about 135° C.; placing a second substrate treatment agent on the water soluble third web; sealing the second web to the water soluble third web to form an enclosed pouch having a second chamber containing the second substrate treatment agent.

The third pressure difference can be applied by applying a third negative gage pressure to the second porous face.

