Applications of Encapsulated Oil Emulsions and Method of Preparation Therefor

This invention relates to encapsulated oil emulsions and methods of preparation of said encapsulated oil emulsions and applications therefor, and in particular encapsulated oil emulsion systems for encapsulating an active ingredient.

The present invention is suited for encapsulation of active ingredients, such as biocidally active products that are directed towards infection/bacterial control, and the use of such products in relation to user products supplied for use in particular environments where such control of infection/bacterial contamination is important, for example, in the Healthcare Industry.

Encapsulated materials have been used for several years in various applications, and consequently, the methodology in creating such encapsulated materials is already in the public domain. The present invention utilises already known encapsulation techniques in creating new and inventive encapsulated products and applications therefor.

For a number of years some user products have included additional materials that provide the user product with an enhanced or beneficial property in order to make the user product more suitable for its particular application. One typical example of this type of enhanced user product would be tissues that include within their infrastructure aloe vera oil extract to act as a softener/lubricator of peoples skin. This application would reduce the effect of wear damage to the skin caused by rubbing of the skin with the bare tissue material. In this application, the aloe vera oil extract is directly located in the infrastructure of the tissue and is not deployed as an encapsulated material. Consequently, these tissues have a shelf life and degrade after a short time.

The present invention is concerned with providing an encapsulation system and technique that can readily be used producing products for use in particular applications. Further said products would have an extended shelf life for the active material and which become activated at the point of use either on dispersal or after a period of time.

In accordance with a first aspect of the present invention, there is provided a product including a particulate material, which particulate material comprises a microencapsulated active ingredient and the encapsulating material forms a shell to seal the active ingredient from the surrounding atmosphere and the active ingredient is released when the encapsulating shell is ruptured or broken and wherein the encapsulated active material is carried in one or more oils selected from aromatic oils, aliphatic oils, paraffϊnic oils or napthenic oils.

The particulate materials are manufactured and suited for dispersal into a particular environment. That environment could require for the most effective operation of the material that the particulate material is capable of being retained in situ for a long period of time. Consequently the properties of the encapsulating material would need to meet certain external factors as well as sealing the active material against premature release and/or loss of efficacy. In one potential usage of the particulate material it may be important to secure the particulate material in place and to enhance this the adherence of the encapsulate material may be further enhanced by the addition of an additional resin, polymeric material or natural adhesive to the encapsulate material. This may be applied at a secondary stage in the manufacture.

The active ingredient may be selected from the following groups of materials

Biocides;

Lubricant additives, such as polyiosbutaliene, or polytetrafluoroethylene (PTFE) or graphite and molybdenum disulphide dispersions; Tracers, for example UV fluorescent tracers; silicone oils: or natural waxes.

The active ingredient may include a mixture of active ingredients including one or more of the above examples.

A product made in accordance with the present invention may comprise a mixture of particulate materials, at least one of which is made in accordance with the present

invention.

The particulate material of the present invention may have a particle size in the range of 5 to 30 microns, and more preferably in the range of 10 to 20 microns, and most preferable in the range of 10 to 15 microns.

In one embodiment of the present invention, the active ingredient includes biocidic material and the active biocide is selected from the group of triclosan (2,4,4'-trichloro-2'- hydroxydiphenyl ether); trichlorocarban (l-(3',4'-dichlorophenyl)-3-(4'- chlorophenyl)urea); PCMX (p-Chloro-m-xylenol); Hexahydro- 1 ,3 ,5,-Tris(2- Hydroxyethyl)-S-Triazine, and DCMX (2,4-Dichloro-3,5-xylenol).

The oil used to carry the encapsulated active material is preferably selected from the group of materials comprising essential oils; naturally derived oils; or petroleum oils.

In accordance with one embodiment of the present invention, the essential oils include peppermint oil; eucalyptus oils; jojoba oils; and sweet almond oil or a mixture thereof.

In accordance with one embodiment of the present invention, the naturally derived oils may be selected from coconut oil; corn oil; and olive oil or a mixture thereof.

The oil used with the present invention may include a mixture of one or more essential oils and one or more naturally derived oils.

In accordance with another embodiment of the present invention, the petroleum oils may be selected from paraffin waxes or polyolefin based oils.

The product made in accordance with the present invention may be a coating material or dispersion such as an aqueous suspension.

It will be noted that all of the above mentioned oils include glycerides, turpenes, esters

and/or hetero-cyclic materials, and the most suitable types of oils selected from each of the groupings will be a liquid material at or below 7O ⁰ C, and also as the preferred method for encapsulating the material comprises and aqueous based dispersion/suspension, the material is preferable not soluble in water and not miscible with water.

The preferred method for micro-encapsulation is melamine/formaldehyde encapsulation. In this system, standard quality melamine and 37% formaldehyde were used as microencapsulate raw materials with suitable surfactant materials and stabilisers, as well as PH controllers. More detail concerning the exact method and materials used to provide example materials of the present invention is provided below.

Suitable final use products for the product of the present invention, include paper towels having a coating including the product of the present invention, as well as other fibrous materials (natural or synthetic), to which the product of the present invention can be adhered; temporary lacquers and coatings; and air fresheners.

With the use of the invention as a coating for paper towels, as the towel is used the particulate material is broken, so releasing the active materials. This is particularly suited for applications where infection/bacterial control is the primary feature to be considered.

With regard to the use of the invention in temporary lacquers and coatings, the invention is directed to use of biocides, which are released over a period of time, so preventing micro-organisms from developing on the treated surface.

In similar regard to the use of the invention, directed towards biocides whose actions might be activated by the passing contact of the surface by persons, animals or objects thereby destroying any micro-organisms.

With regards to use in an air freshener, the encapsulated material is expelled in the aerosol with the particles towards the periphery of the spray being ruptured/broken on ejection, and the particles in the central area of the spray being allowed to fall and rest on

surrounding surfaces. The particles allowed to fall and rest will be ruptured/broken subsequently by, for example, people walking in he room and crushing the settled particles. One particular example of the invention envisaged would be as a means to supply treatment agents or paliative materials for the control of asthma where the aerosol is sprayed over the patients pillow and the particular material is ruptured through the night by the movement of the patient.

The invention will now be described by way of example.

The method used to encapsulate the active materials is as follows.

Standard quality melamine, 37% formaldehyde were used as the micro-encapsulate wall material; sodium lauryl sulphate (SLS) and Tween 20 were used as surfactants; and poly vinyl alcohol (PVA) as a stabiliser. Further, sodium hydroxide and citric acid were used as pH controllers.

In order to prepare the micro-capsules for encapsulation, two sets of equipment were required to produce the micro-encapsulates. The specification for the apparatus comprised an overhead stirrer, capable of stirring a maximum of 15 litres at 2000 rpm; a hot plate with a temperature range of 20 to 200 ⁰ C and a balance capable of weighing a minimum of 200 grams with an accuracy of at least 0.01 grams were provided. Other equipment included one litre beakers, 0 to HO ⁰ C thermometers, stirring rods, paddle heads and a PH probe.

A solution of melamine, formaldehyde and water was prepared and heated to approximately 85 ⁰ C, whilst continuously stirring at 200 rpm. Once a clear liquid had formed, the PH was adjusted to be between 8.7 and 8.9.

An oil in water emulsion was prepared using the selected oil. A solution of SLS dissolved in water was prepared. A solution of Tween 20 in the selected oil was also prepared.

The SLS solution and the Tween 20 solution were steadily added to one another, with continuous stirring at 200 rpm.

A small quantity of PVA emulsion was added after approximately ten minutes stirring to assist the emulsion stability. The PH of the resultant emulsion was adjusted to approximately 7.5 and the solution heated to a temperature of approximately 5O ⁰ C.

The melamine/forrnaldehyde solution was slowly added to the emulsion mentioned above, and the PH adjusted to approximately 5.5 to 6. Throughout this process, a steady temperature of 50 ⁰ C was maintained and the reaction allowed to progress for a period of two to four hours whilst maintaining this steady temperature. A few drops of isopropyl alcohol were added to the resultant solution to terminate the reaction.

Using the above-mentioned methodology, the following examples of emulsion materials were prepared. All the composition detail provided below is provided as W/W%.

The following examples were prepared by the methodology above where the selected biocide was incorporated to fall within the range 0.25% - 2.00% expressed on the weight of the incorporated oil.

Example 1

Example 2

Example 3

Example 4

Example 5

The above-mentioned sample materials were then used to produce certain derived products examples of which are given below. It should be noted that any of the examples above can be substituted in the product examples. The actual choice will depend on the particular application or use that is being considered and a particular system can be

applied to particular circumstances.

Aerosol Coating

Samples of the above mentioned bases were diluted with water and an alcohol solvent to form a base material for packing into aerosol sprays. The propellant material used was that typically used with current aerosols, namely (1,1 Dichloro-1-Fluoroethane, 1,1,1,2 Tetrafluoroethane , or Butane/Propane mixtures).

The emulsion described in example 3, was prepared in a formulation of 20.33%, with isopropyl alcohol 36.88% and water 42.79%.

When the formulation is dispensed from the aerosol, the product is dispersed to form a fine mist of micro-capsules which settle on the sprayed surface to produce a fine film, and the capsules are bound to the surface on drying by the included PVA resin. On disbursal from the aerosol, the micro-capsules towards the periphery of the spray plume are ruptured/broken, providing immediate activation of the active material contained within the formulation.

Paper Towel In this particular derived product, the material details in example 1 above were used to produce a coating on commercially available paper towels. The particulate matter of the present invention is disbursed into the interstices of the fibres make up of the towel, so that when the towel is used for cleaning hand, the micro-capsulate particulate is broken, so that the towels sanitise the skins surface.

Hard Surface Coating

The present invention can be provided for supply as a hard surface coating for coating of, for example, concrete surface. In this particular example, a biocidal particulate material and examples of formula used in these flooring surfaces are as follows.

Example A

Jojoba oil / PCMX base 20.5; Acrylic resin solution 8.8; and Water 71.7

Example B

Peppermint oil / triclosan base 19.5; Acrylic resin emulsion 10; and Water 70.5