WO2025131974A1

WO2025131974A1 - Method for manufacture of a water-soluble package for holding a detergent composition

Info

Publication number: WO2025131974A1
Application number: PCT/EP2024/085852
Authority: WO
Inventors: Alias Younis AL-BAYATI; Eleanor JENKINSON; Torsten Roth
Original assignee: Reckitt Benckiser Finish BV
Current assignee: Reckitt Benckiser Finish BV
Priority date: 2023-12-21
Filing date: 2024-12-12
Publication date: 2025-06-26
Anticipated expiration: 2026-06-21
Also published as: GB202319729D0

Abstract

The invention relates to a method of manufacturing a water-soluble package for holding a detergent composition, the method comprising: i) providing a liquid polyvinyl alcohol (PVOH) composition; ii) printing a first composition onto a transfer surface; iii) forming a PVOH membrane precursor on the transfer surface by depositing the liquid PVOH composition onto the transfer surface; iv) allowing the PVOH membrane precursor to solidify to form a first PVOH membrane comprising the first composition; and v) forming a water-soluble package comprising the first PVOH membrane.

Description

Method for manufacture of a water-soluble package for holding a detergent composition

The present invention relates to a method of providing a water-soluble package for holding a detergent composition, such as an automatic dishwasher detergent pouch, with an improved appearance or functional performance. In particular, the method provides approaches to providing branding or consumer-relevant information on a PVOH pouch.

Consumer products are commonly provided with branding to generate brand-awareness and to emphasise the premium appeal of products. It is also known to provide certain products, such as detergents, with safety information to meet certain regulatory requirements and to assist the end consumer. There are, however, certain products where it has historically been very difficult to provide this information. With such products it has generally been necessary to provide the information on secondary packaging or to provide the information using expensive or complex labelling or other processes.

WO2015160739 describes an apparatus for producing a printed film employing a PVOH homo- or co-polymer film roll and a rotating drum printing system.

WO2019099183 describes a process of transferring a UV (ultraviolet) curable ink composition onto a three-dimensional article.

EP2508436 describes a method for flexographic printing on a water-soluble detergent pouch.

US9969895 describes a process for printing on a water-soluble material using a self- dispersible pigment.

US8087357 describes a process for selectively and repeatedly printing at least two graphics onto a water-soluble material.

It is an object of the present invention to provide a new method for providing information and/or functional ingredients on a range of PVOH water-soluble packaging, or at least to tackle problems associated therewith in the prior art or provide a commercially viable alternative thereto. According to a first aspect there is provided a method of manufacturing a water-soluble package for holding a detergent composition, the method comprising: i) providing a liquid polyvinyl alcohol (PVOH) composition; ii) printing a first composition onto a transfer surface; iii) forming a PVOH membrane precursor on the transfer surface by depositing the liquid PVOH composition onto the transfer surface; iv) allowing the PVOH membrane precursor to solidify to form a first PVOH membrane comprising the first composition; and v) forming a water-soluble package comprising the first PVOH membrane.

The present disclosure will now be described further. In the following passages different aspects/embodiments of the disclosure are defined in more detail. Each aspect/embodiment so defined may be combined with any other aspect/embodiment or aspects/embodiments unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous. It is intended that the features disclosed in relation to the product may be combined with those disclosed in relation to the method and vice versa.

The present inventors have surprisingly found that certain compositions can be controllably transferred into flowable compositions of water-soluble PVOH films. The method was found to apply to both PVOH aqueous solutions and melts, during cast extrusion or solution casting processes, respectively. Cast extrusion and solution casting are discussed in more detail in WO 2022/253814 and WO 2023/174694 which are incorporated herein by reference. The transfer was able to produce an aesthetic benefit to the final film, enhancing the premium appeal of a branded product (e.g., visual, tactile, etc.), or to convey consumerrelevant product information (e.g., product identifier objects such as QR codes, usage instructions, warning symbols, caution statements, product logos, ingredients, etc.). Furthermore, depending on the selected composition, the techniques could be applied to impart additional functional benefits (e.g., material care actives).

The inventors found, in particular, that the desirable modifications could be achieved by solution casting a liquid PVOH material onto an ink/dye/colorant-coated surface, or by a cast-extrusion process wherein a molten PVOH material is extruded onto a chill roll precoated with ink/dye/colorant/ingredient for transfer. A number of particular benefits were observed compared to the established prior art. For example, whereas standard printing on water-soluble films is a two-step process, the approach described herein combines the film formation and a deposition of various ingredients on its surface. Thus, the process is quicker and less complex. The route herein allows the combination of surface structure modifications and the deposition of chemicals in a single step, and it can be performed using the conventional equipment in place, with only minor additional equipment (e.g., a printer).

In contrast, the standard off-line printing employs excessive process steps and significantly slows the process of producing packaging. Further, because the printing process is distinct from the actual packing process, the necessary equipment is remote from one another and therefore the entire operation requires a large area.

Furthermore, excessive manipulation of the water-soluble film in unwinding and rewinding the film may affect the integrity and robustness of the water-soluble film itself. Loss of integrity and robustness will negatively affect the quality of the final product. Excess manipulation can also lead to increased scrap levels due to start-up and shutdown of each process. Costs associated with handling this scrap must also be considered. Another disadvantage of off-line printing is the storage of the printed material, which requires additional space to be stored. Off-line printing also creates a risk of printing an excess of a design.

Many commercially available products with water-soluble films contain printed safety information displaying designs or safety information. Current applications range across dishwashing, laundry, and household cleaning products with the capability to transcend into further markets.

The present invention relates to a method of manufacturing a water-soluble package for holding a detergent composition. Suitable water-soluble packages, also known as pouches, are well known in the art. They are used, for example, for holding automatic dishwashing (ADW) detergent compositions, whereby in use the material forming the pouch (typically PVOH) softens and the package releases the detergent. During the course of the wash, the full package material desirably dissolves so that it does not leave any residue. The dissolution of the package can be used to achieve timed release of detergent ingredients and the package can be comprised of multiple compartments holding detergent ingredients separate from one another.

The precise nature of the detergent composition that can be held is not critical to the present invention. The composition will, however, typically be anhydrous to avoid softening of the PVOH package before use. Preferably the detergent composition is a dishwashing detergent composition, preferably an ADW dishwashing detergent composition for release during a dishwashing cycle. Alternatively, the detergent composition may be a laundry detergent composition.

The method comprises providing a liquid polyvinyl alcohol (PVOH) composition. PVOH is a well-known water-soluble film material for use in making packages for holding detergent compositions. PVOH is commonly produced from the hydrolysis of polyvinyl acetate (PVA) in the presence of methanol and a catalyst (for example, sodium hydroxide). The properties of the polymer can be affected by the degree to which the polyvinyl acetate has been hydrolysed. For example, the higher the degree of hydrolysis, the less water-soluble the PVOH. As a result of the hydrolysis method using polyvinyl acetate, the PVOH may comprise some acetate groups. Preferably the PVOH comprises at most 15 mol% acetate groups, preferably less than 10 mol% acetate groups, more preferably at most 8 mol% acetate groups.

The degree of hydrolysis is known to influence the temperature at which the PVOH starts to dissolve in water. A degree of hydrolysis of 88% corresponds to a film soluble in cold (i.e., room temperature of 20°C) water, whereas a degree of hydrolysis of 92% corresponds to a film soluble in warm water. The film may be cast, blown or extruded. It may further be unoriented, mono-axially oriented or bi-axially oriented.

As will be apparent, the present invention employs two different primary methods to achieve the inclusion of the first composition on the surface of the PVOH membrane - solution casting and cast extrusion. These underlying methods are well known for the formation of PVOH films and are discussed in more detail below. In each instance the method relies on a liquid form of PVOH, in contrast to the solid (albeit flexible and soft) form of the PVOH membrane in a final product. In solution casting the PVOH is liquid because it is provided as a dissolved aqueous solution, whereas in cast extrusion the PVOH is provided as a molten composition. Nonetheless, in each instance, the form of the PVOH is liquid.

The method comprises printing a first composition onto a transfer surface. Preferably the first composition in step ii) is an ink composition. The precise nature of the first composition is not critical since it has been found that a wide range of materials can be suitably transferred by the present method. It will be appreciated that the first composition can be selected to ensure sufficient compatibility with the PVOH such that it is transferred to the PVOH in step iv). For convenience and since the primary object of the invention is to convey information on the product packaging, it is preferred that the composition is an ink. Inks are well known in the art and can be used and applied using conventional printing processes, such as ink-jet printing.

A preferred ink composition is one comprising one or more pigments, dyes or colorants. Preferably the ink is not a permanent ink and it may, instead be a non-permanent or transferable ink formulation. This will increase the transfer to the PVOH in the present method and may help to increase the definition in the transferred images.

An alternative first composition comprises one or more functional ingredients, preferably a material care agent. Suitable functional ingredients include chemicals that are intended to be part of a washing process, such as surfactants. Preferred surfactants include anionic or non-ionic surfactants, preferably those which are water soluble. Advantageously, by providing such chemicals in this way, they can be provided on the surface of the package, such that they may dissolve into a washing medium before or concomitantly with the opening of the PVOH package during a washing cycle. It will generally be the case that these will also be printed onto the transfer surface using a conventional printing technique.

An exemplary non-permanent ink is described in US8227524. This describes how a typical ink composition comprises a combination of a solvent, hydrophobic surfactant (e.g, a fluorosurfactant), a pigment, a dispersant, and water. A combination of water and solvent based inks is what provides an optimal drying rate when printed on a surface. Suitable inks may also contain resin as the binder, solvents as the majority component in the ink formulation, surfactants to reduce the surface tension of the liquid to make it jet well onto a surface, defoamer to avoid bubbles during printing, and/or rheology modifiers for an optimal viscosity. Dyes may be cationic and/or anionic. Preferably the ink composition comprises a solvent, a pigment, a dispersant, and water, and optionally further comprises a hydrophobic surfactant and/or a resin and/or a defoamer and/or a rheology modifier.

The act of printing is synonymous with deposition of the first composition and will depend on the precise nature of the printing apparatus used. Ink-jet printing is especially preferred for its accuracy and flexibility in the present invention.

The transfer surface is the surface onto which the liquid PVOH would normally be placed to form a film in a conventional film formation process. Accordingly, in solution casting, the transfer surface is typically the surface onto which the aqueous solution of PVOH is normally cast. In a cast extrusion process, the transfer surface is typically the surface of the chill roller onto which the extruded molten PVOH is directed for shaping and cooling. In each instance, preferably the transfer surface is a non-absorbent substrate. This helps to ensure transfer of the first composition from the transfer surface to the PVOH in the subsequent step. In the Examples below, the printing was done onto transparent glossy plastic sheets and PVOH was solution cast or extruded on this. Preferably, the transfer surface is a hydrophobic water-repellant plastic sheet and may, for instance, be an acetate or polyester sheet.

The method comprises forming a PVOH membrane precursor on the transfer surface by depositing the liquid PVOH composition onto the transfer surface. Since the first composition has been printed onto the transfer surface before this deposition step, the PVOH will contact the first composition on the transfer surface. As shown in the Examples, this can then be efficiently transferred into the PVOH film as the PVOH undergoes a state change to solid (i.e., drying or solidifying).

The method comprises allowing the PVOH membrane precursor to solidify to form a first PVOH membrane comprising the first composition. Depending on the process that is employed, the step of solidifying can include a step of active cooling (such as cooled chill rollers in cast extrusion) or active drying (such as with forced air when solution casting). Such steps are well known and conventional in the art. The method comprises forming a water-soluble package comprising the first PVOH membrane. It is to be understood that the first PVOH membrane forms part of the package itself rather than being held by or contained within the package. In other words, the method comprises forming a water-soluble package from the first PVOH membrane. Techniques for forming such a package are well-known in the art.

Preferably the surface containing the first composition is used as the body of a package. Preferably step v) comprises: a) thermoforming the first PVOH membrane to produce at least one pocket; b) at least partially filling the or each pocket with a detergent composition; and c) placing a second PVOH membrane on top of the or each filled pocket; and d) sealing the first PVOH membrane and the second PVOH membrane together.

Alternatively or in addition, preferably the surface containing the first composition is used as the lid or sealing portion of a package. Preferably step v) comprises: a) thermoforming a second PVOH membrane to produce at least one pocket; b) at least partially filling the or each pocket with a detergent composition; and c) placing the first PVOH membrane on top of the or each filled pocket; and d) sealing the first PVOH membrane and the second PVOH membrane together.

Preferably the first composition is provided on an outer surface of the water-soluble package. This means that any functional compound is exposed quickly to the washing medium in use. It also means that any ink is not exposed to any detergent held within the package and does not need to be read through the thickness of the formed PVOH film.

Preferably the first PVOH membrane and, where present, the second PVOH membrane, each have a thickness of 60 to 200 pm, preferably 70 to 120 pm. These thicknesses are optimal for applications where the PVOH will suitably dissolve in a wash cycle and detergent held in the package will be suitably released. Preferably the package is a multicompartment detergent package.

A preferred embodiment of the method will now be described further in which the method comprises a cast extrusion process. Preferably the cast extrusion process involves the following steps: in step i) the liquid PVOH composition is a melted PVOH composition; in step ii) the transfer surface is a contact surface of a chill roller; in step iii) the PVOH membrane precursor is formed by extrusion through a die, and in step iv) the PVOH membrane precursor is cooled to solidify, thereby forming the first PVOH membrane comprising the first composition.

A simplified overview of the cast extrusion process and its corresponding film states is provided as follows: i) an extruder produces a liquid flowable melt, at an elevated temperature. The PVOH is in a liquid form. ii) the melt exits the extruder die and passes over the first chill roll. The PVOH is in a liquid or malleable gel form. In accordance with the invention, the chill roller is preprinted with the first composition, such as branding or consumer instructions. iii) the melt passes over subsequent chill rolls and becomes solid at a lower temperature. iv) the film is cut and wound onto a reel.

In prior art processes, this approach would not have had the composition pre-loaded onto the chill roller and there would be a further step of unrolling and printing on the reel of film.

A preferred embodiment of the method will now be described further in which the method comprises a solution cast process. Preferably the solution cast process involves the following steps: in step i) the liquid PVOH composition is an aqueous PVOH solution; in step ii) the transfer surface is a casting surface; in step iii) the PVOH membrane precursor is formed by solution casting, and in step iv) the PVOH membrane precursor is dried to solidify, thereby forming the first PVOH membrane comprising the first composition.

A simplified overview of the solution casting process and corresponding film states is provided as follows: i) an aqueous solution of PVOH is formed in a liquid state with a high moisture content. ii) the solution is cast onto a surface which, in accordance with the invention has been pre-printed with the first composition, such as branding or consumer instructions. iii) the solution is dried, first becoming a malleable gel and then a solid as the moisture content is reduced. Note, once the film reaches its solid state, no more ink transfer occurs. iv) the film is transferred to a reel and wound.

In prior art processes, this approach would not have had the composition pre-loaded onto the chill roller and there would be a further step of unrolling and printing on the reel of film. The water content of the casted film changes substantially (from high to low) over the course of the solution casting and drying process.

According to a further aspect there is provided a water-soluble package obtained or obtainable by the method described herein.

According to a further aspect there is provided the use of a water-soluble package as described herein to package a detergent composition, preferably a dishwashing detergent composition or a laundry detergent composition, more preferably an automatic dishwashing detergent (ADW) composition.

Examples

The invention will now be described further in relation to the following non-limiting Example.

Example 1

Trial 1

Initially, an aqueous solution of PVOH was cast onto surfaces using an Erichsen Coatmaster 510 Basic-G. During trials, it was noticed that inks and colorants on the casting surface could be transferred onto the surface of a newly casted film. Notably, this transfer is only viable if the PVOH solution remains in a liquid or malleable state, and if it does not occur effectively with a finished PVOH film. Once the casted film had dried, it was removed from the surface and the ink was fully transferred into the film. Trial 2

Next, labels were printed using a DYMO LetraTag 100H Label Maker and DYMO LetraTag Plastic Labels in White. The device uses thermal printing to print black text onto "white paper" label strips. When a PVOH solution was cast upon the label, the ink and the white background were transferred to the surface of the film.

Trial 3

Subsequently, using the Silhouette Cameo 4 Plus Plotting Device and a semi-permanent ink marker, a design was drawn upon a PVC (Poly Vinyl Chloride) plastic sheet. Then, an aqueous PVOH solution was cast upon the surface with the Erichsen Coatmaster 510 Basic-G; all ink transferred into the film. It was noted that when a permanent ink marker was used, the ink did not transfer effectively. Inks which are marketed as permanent to prevent or limit the "bleeding" of inks may reduce the clarity of the chosen designs using the inventive process.

Trial 4

A design was printed onto an LMG Premium Inkjet Transparency Paper using a Canon Pixma TR4500 Inkjet Printer. Next, a solution of PVOH in water was cast upon the surface using the Erichsen Coatmaster 510 Basic-G device. Again, the design transferred into the film and no ink was left on the surface of the transparency paper. The final film displayed high clarity and even small designs and letters remained legible, including a scannable QR code.

The methods outlined above differ from current printing methods which print onto water- soluble films in a secondary stage, post film production. Among the distinctions between the work herein and the prior art, the rheological properties, the flowability and the malleability, of the films while the ingredient, dye, etc. is transferred, are substantially different, as these characteristics change along the stages.

All percentages are by weight unless otherwise specified. The foregoing detailed description has been provided by way of explanation and illustration and is not intended to limit the scope of the appended claims. Many variations in the presently preferred embodiments illustrated herein will be apparent to one of ordinary skill in the art and remain within the scope of the appended claims and their equivalents.

For the avoidance of doubt, the entire contents of all documents acknowledged herein are incorporated herein by reference.

Claims

Claims:

1 . A method of manufacturing a water-soluble package for holding a detergent composition, the method comprising: i) providing a liquid polyvinyl alcohol (PVOH) composition; ii) printing a first composition onto a transfer surface; iii) forming a PVOH membrane precursor on the transfer surface by depositing the liquid PVOH composition onto the transfer surface; iv) allowing the PVOH membrane precursor to solidify to form a first PVOH membrane comprising the first composition; and v) forming a water-soluble package comprising the first PVOH membrane.

2. The method according to claim 1 , wherein the first composition in step ii) is an ink composition comprising one or more pigments, dyes or colorants, and/or wherein the first composition comprises one or more functional ingredients, preferably a material care agent.

3. The method according to claim 2, wherein the ink composition comprises a solvent, a pigment, a dispersant and water, and optionally further comprises a hydrophobic surfactant and/or a resin and/or a defoamer and/or a rheology modifier.

4. The method according to any preceding claim, wherein the method comprises a cast extrusion process, preferably wherein: in step i) the liquid PVOH composition is a melted PVOH composition; in step ii) the transfer surface is a contact surface of a chill roller; in step iii) the PVOH membrane precursor is formed by extrusion through a die, and in step iv) the PVOH membrane precursor is cooled to solidify, thereby forming the first PVOH membrane comprising the first composition.

5. The method according to any of claims 1 to 3, wherein the method comprises a solution cast process, preferably wherein: in step i) the liquid PVOH composition is an aqueous PVOH solution; in step ii) the transfer surface is a casting surface; in step iii) the PVOH membrane precursor is formed by solution casting, and in step iv) the PVOH membrane precursor is dried to solidify, thereby forming the first PVOH membrane comprising the first composition.

6. The method according to any preceding claim, wherein step v) comprises: e) thermoforming the first PVOH membrane to produce at least one pocket; f) at least partially filling the or each pocket with a detergent composition; g) placing a second PVOH membrane on top of the or each filled pocket; and h) sealing the first PVOH membrane and the second PVOH membrane together.

7. The method according to any of claims 1 to 5, wherein step v) comprises: e) thermoforming a second PVOH membrane to produce at least one pocket; f) at least partially filling the or each pocket with a detergent composition; g) placing the first PVOH membrane on top of the or each filled pocket; and h) sealing the first PVOH membrane and the second PVOH membrane together.

8. The method according to any preceding claim, wherein the first composition is provided on an outer surface of the water-soluble package.

9. The method according to any preceding claim, wherein the first PVOH membrane and, where present, the second PVOH membrane, has a thickness of 60 to 200 pm, preferably 70 to 120 pm.

10. The method according to any preceding claim, wherein the package is a multicompartment detergent package.

11 . The method according to any preceding claim, wherein the detergent composition is a dishwashing detergent composition, preferably a machine dishwashing detergent composition for release during a dishwashing cycle.

12. A water-soluble package obtained or obtainable by the method according to any preceding claim.

13. The use of a water-soluble package according to claim 12 to package a detergent composition, preferably a dishwashing detergent composition or a laundry detergent composition, more preferably an automatic dishwashing detergent composition.