WO1990010436A2

WO1990010436A2 - Membrane encapsulated essential oil

Info

Publication number: WO1990010436A2
Application number: PCT/CA1990/000085
Authority: WO
Inventors: Ying Wang; Qilian Yang
Original assignee: International Applied Sciences, Inc.
Priority date: 1989-03-15
Filing date: 1990-03-14
Publication date: 1990-09-20
Also published as: IL93736A0; WO1990010436A3; AU5336390A; CN1045599A

Abstract

A perfuming agent which contains one or more of an essential oil capsule having a core of essential oil encapsulated within a membrane, the essential oil capsule being dispersed in an aqueous solution containing a surfactant. A method of preparing the perfuming agent and the use of the perfuming agent to scent a substrate is also provided.

Description

- 1 - _ -

TITLE. MEMBRANE ENCAPSULATED ESSENTIAL OIL

FIELD OF THE INVENTION

This invention generally relates to the fields of perfuming and membrane technology.

BACKGROUND OF THE INVENTION

Generally, essential oils are volatile materials produced from odorous plant material by water or steam distillation or by expressing. Examples of natural essential oils used in perfume include ambergris, benzoin, cast oreum, civet, clove leaf oil, galbanum, jasmine absolute, labdanum, mate, melilot, mimosa, musk tonquin, myrrh, oakmoss or mousse de chene, olibanum, opopanax, orris, patchouli, rose, rosemary oil, sandalwood oil, vetivert oil a d violet leaves absolute_* Many essential oils are also made synthetically.

Perfuming agents applied to substrates such as air fresheners contain an essential oil and ethanol solvent. Ethanol is used since the essential oil generally is not soluble in water. A disadvantage with perfuming agents employing ethanol is that both the ethanol and any alcohol and fusel oil in the ethanol give off an odour which may affect the quality of the fragrance. Furthermore, ethanol may irritate skin which limits its usefulness in a perfuming agent. Traditional methods of extending the release time of a small amount of essential oil in a perfuming- agent- include the addition of a carrier liquid such as polyethenoL res in, oleic acid,and glyceroX tα theperfuming; agent. These techniques, however, do not give the desired ^" amount of control over the release of the fragrance.

A more recent method includes the addition of a surfactant to the perfuming agent to dissolve the essential oil on the surfactant to form minute capsules having a diameter of less than 0.05 micron. The capsules separate out of the ethanol solution, thereby reducing the quantity present using this method which gives rise to the problem of an overly-fast release rate of the essential oil with a resultant undesirable scent.

It is desirable, therefore, to increase the release time of perfuming agents and to produce perfuming agents without the use of ethanol to both increase the quality of the perfuming agent and any substrate treated with this agent, preferably at a reasonable manufacturing cost.

SPMMARY OF THE INVENTION The present invention provides a perfuming agent comprising one or more of an essential oil capsule having a core of essential oil encapsulated within a membrane, the essential oil capsule being dispersed in an aqueous solution containing a surfactant. The invention also provides, a method of preparing a perfuming agent having one or more of an essential oil capsule dispersed in an aqueous solution containing a surfactant, the method comprising encapsulating an essential oil within a membrane, the encapsulating being effected by forming the membrane by contacting the essential oil with an aqueous solution containing a membrane forming material, a surfactant and a solvent capable of dissolving one or both of the essential oil or membrane forming material to form an essential oil droplet; crosslinking the membrane forming material to produce a membrane about the essential oil droplet by subjecting the essential oil droplet to a cross-linking agent; and allowing the solvent to evaporate to form an essential oil capsule. The invention further relates to the use of the perfuming agent of the invention to scent a variety of substrates; for example, cloth, wallpaper, silk flowers, dried natural flowers, shirts and air fresheners. __*- ^ _^

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by reference to the appended drawings in which:

Figure 1 diagrammatically shows the components of the perfuming agent of the invention during formation; and.

Figure 2 diagrammatically shows a formed essential oil capsule of the invention.

DETAILED DESCRIPTION OF THE INVENTION

As mentioned hereinbefore, the present invention provides a perfuming agent comprising one or more of an essential oil capsule having a core of essential oil encapsulated within a membrane, the essential oil capsule being dispersed in an aqueous solution containing a surfactant. Essential oils which may be used in the perfuming agent are rose oil, lilac oil or any other- variety of non-water soluble essential oils. The essential oils obtained from natural products or synthetic essential oil may be used in the perfuming agent of the invention.

The surfactant which may be used in the perfuming agent of the invention is typically odourless. Examples of suitable surfactants include dodecyl sodium sulfate (DSS), sodium alkylsulfonate, polythene oxide, polyethenol, sodium oleate and sodium napthylate.

The essential oil capsules have a low surface tension, generally about 40 dyne per centimetre² so that they have generally good absorbability.

The essential oil capsules contain molecular interstices on their surfaces through which, the essential oil can permeate. Preferably, the. size of the molecular interstices may be selected so as to give a relatively even rate of fragrance release.

The diameter of the essential oil capsules is typically in the range of .05 to 50 microns and correspondingly, the surface area of the essential oil capsules is large. Thus, the capsules contain a relatively large amount of essential oil so that a substrate on which such capsules is deposited will be able to release fragrance over a longer period of time than a substrate treated directly with an essential oil in alcohol. Also, when alcohol is not used as the solvent, there is no negative effect from the smell of the alcohol on the scent of the essential oil.

The perfuming agent of the present invention is prepared by encapsulating the essential oil with a membrane. The encapsulation is effected by forming the membrane by contacting the essential oil with an aqueous solution containing a membrane-forming material, a surfactant and a solvent capable of dissolving one or both of the essential oil or membrane-forming material to form an essential oil droplet. The membrane forming material is crosslinked to produce a membrane about the essential oil droplet by subjecting the essential oil droplet to a cross¬ linking agent. The solvent is then, allowed to evaporate, to form an essential oil capsule.

The essential oils and surfactants which may be used in the method of the invention have been described above.

Suitable membrane-forming material which may be used in the method of the invention include organosilane or organosilicone rubber, in particular, methyl siloxane, ethyl siloxane or ethenyl siloxane. Typically, the concentration of the membrane forming material is from about 5 to 35% by weight.

Suitable crosslinking agents which may be used in the.- process of the invention include phosphoric acid, ethyl silicic acid, organic zinc. Typically the concentration, of crosslinking agents is. from,about.0.5, tα.5%. by weight.

Suitable solvents which may be used in the process of the invention include petroleum ether and benzene typically in concentrations of from about 30 to 85% by weight.

A detailed description of the formation of a preferred perfuming agent of the invention will now be discussed.

The surfactant is first dissolved in water to prepare a water/surfactant solution. A second solution is prepared _ ₅ _

by combining the membrane forming material, the crosslinking agent, the solvent and the essential oil.

The essential oil may be rose oil or any other variety of non-water soluble essential oil in a concentration of 5 from 5 to 35% by volume. The water/surfactant solution may be stirred in a mixer at approximately 100 revolutions per minute for from about 1 to 120 minutes. The second solution is added to the water/surfactant solution slowly while stirring and stirring is continued for 1 to 20 hours

10 after all of the second liquid has been added. After a period between about 1 to 20 hours has elapsed, the resulting mixture may be passed through a filter in- a separating funnel to separate out the water and surfactant. The filter should stop the passage of particles greater

15 than approximately 20 microns. In this manner, a concentrated solution of perfuming agent is formed. During this process, the weight ratio of the water/surfactant and second liquid is controlled from 100:10 to 100:200.

Microscopic examination of membrane encapsulated

20 essential oil droplets produced using the above method shows them to be approximately 5 to 25 microns in size and having a membrane thickness of approximately 2 - 3 microns. The content of essential oil inside the capsules is from 70 - 90% of the total volume of the capsules.

25 The perfuming agent of the present invention may be used to spray or coat for example, cloth, wallpaper, paper, silk flowers, dried natural flowers and shirts. Various sizes of molecular interstices on the surface polymer membrane may be used to give fragrance release times fro

30. 5 to 100 days.

In accordance with the objects and principles of the invention, and the accompanying drawing, a perfuming agent generally designated 2 is provided. In Figure 1, an essential oil droplet 11 is shown surrounded by a solvent

35 13 containing membrane forming material 12. The solvent 13, membrane forming material 12 and essential oil droplet /10436 _ g _

11 are suspended within a water/surfactant solution 15. Reference 14 indicates a surfactant layer.

Once the solvent evaporates from the system shown in Figure 1, ^"the water and essential oil, which are immiscible, are separated by a layer of membrane 16. The membrane generally has the shape of a hollow space with the essential oil droplet 11 contained therein. Outside of the membrane 16 is the water and surfactant solution 15. The essential oil capsules dispersed in the water and surfactant solution is referred to herein as a perfuming agent.

The present invention may be further illustrated by reference to the following examples.

Example A A perfuming agent with a lilac scent was prepared using the solutions described belo r

A water/surfactant solution was made by dissolving 0.25 g of dodecyl sodium sulfate. in 99.75 g of water.

A second solution was prepared by combining 10 g dimethyl siloxane, 10 g ethyl silicic acid, 0.5 g zinc dodecylate, 10 g lilac essential oil and 28.5 g petroleum ether. The second liquid was stirred for twelve hours at a temperature of 60°C and a stirring speed of 40 rpm.

The water surfactant solution was first stirred in a mixer at approximately 100 revolutions per minute from 1 to 120 minutes. The second solution was added to the water/surfactant solution slowly while stirring. The mixture was stirred for 1 to 20 hours after which it was passed through a filter (approximately 20 μ.) in a separating funnel to separate out the water and surfactant

Example B

A perfuming agent with an otto of rose style essential oil was prepared using the solutions described below:

A water/surfactant solution was prepared by dissolving 1 g sodium alkyl sulfonate in 99 g of water. _ _

A second solution was prepared by combining 10 g of essential oil, 10 g diethenyl siloxane, 10 g of 15% phosphoric acid solution and 25 g of benzene. The second solution was stirred for 16 hours at 65°C and a stirring speed of 60 rpm.

The method of preparing the perfuming agent was as described in Example A.

Example C

A perfuming agent with jasmin essential oil was prepared using the solutions described below:

A water/surfactant solution was prepared by dissolving 0.5 g polyethenyl oxide in 99.5 g water.

A second solution was prepared by combining 5 g of jasmin essential oil, 3 g of diethenol metholcyloxane, 5 g of phosphoric acid solution and 17 g of benzene. The second solution was stirred for 10 hours at a temperature of 65°C and a stirring speed of 40 rpm.

The method of preparing the perfuming agent was as described in Example A. It is to be understood that variations to the above specific examples may be apparent to one skilled in the relevant art without departing from the spirit and scope of the present invention.

Claims

We Claim:

1. A perfuming agent comprising one or more of an essential oil capsule having a core of essential oil encapsulated within a membrane, the essential oil capsule being dispersed in an aqueous solution containing a surf ctant.

2. The perfuming agent as claimed in claim 1, wherein the essential oil capsule has a diameter of from about 0.05 to 50 microns.

3. The perfuming agent as claimed in claim 1, wherein the membrane has a thickness of between about 2 to 3 μ and consists of crosslinked organosilane or organosilane rubber.

4. The perfuming agent as claimed in claim 1, wherein the volume of essential oil in the essential oil capsule is from 70 to 90 % of the total volume of the essential oil capsule.

5. A method of preparing a perfuming agent having one or more of an essential oil capsule dispersed in an aqueous solution containing a surfactant, which comprises encapsulating an essential oil within a membrane, the encapsulating being effected by forming the membrane by contacting the essential oil with an aqueous solution containing a membrane forming material, a surfactant and a. solvent capable of dissolving,one o both, of the essential oil or membrane forming material to form an essential oil droplet; crosslinking the membrane forming material to produce a membrane about the essential oil droplet by subjecting the essential oil droplet to a cross-linking agent; and allowing the solvent to evaporate to form an essential oil capsule. _ - _

6. The method as claimed in claim 4 wherein the essential oil is an non-water soluble essential oil.

7. The method as claimed in claim 6, wherein the essential oil is rose oil, lilac oil or jasmin oil.

8. The method as claimed in claim 5, wherein the surfactant is selected from the group consisting of dodecyl sodium sulfate (DSS), sodium alkylsulfonate, polythene oxide, pαlyethenol, sodium oleate and sodium napthylate.

9. The method as claimed in claim 5, wherein the membrane forming material is selected from the group consisting of organosilane and organosilicone rubber.

10. The method as claimed in claim 8, wherein. he membrane forming material is selected from the- group consisting of organosilane and organosilicone rubber.

11. The method as claimed in claim 9, wherein the membrane material is selected from the group consisting of methyl silane, ethyl siloxane or ethenyl siloxane.

12. The method as claimed in claim 9 or 10, wherein the concentration of the membrane forming material is between about 5 to 35%.

13. The method as claimed in claim 9, 10 or 11, wherein the crosslinking agent is phosphoric acid, ethyl, silica acid or organic zinc.

14. The use of a perfuming agent as claimed in claims 1 to 4, to scent a substrate.

15. The use as claimed in claims 14, wherein the substrate is cloth, wallpaper, silk flowers, dried natural flowers, shirts or air fresheners.