GB1598449A - Airtreating gels - Google Patents

Description

(54) AIR-TREATING GELS (71) We, SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ B.V., a Company organised under the laws of the Netherlands, of 30 Carel van Bylandtlaan, The Hague. The Netherlands, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to air-treating gels.

Air treating compositions in the form of gels, e.g. air-freshening gels, are well known consumer products.

One type of composition, known as water-based gels, comprises a polysaccharide as gelling agent, an aqueous medium and a volatile air-treating component e.g. an odorant or a pesticide. The amount of water in such gels usually exceeds 80%w (weight, percent) and the polysaccharide is usually a carrageanate or an alginate. The aqueous medium may contain a small amount, usually less than 10%w, of an anti-freeze such as isopropanol, propylene glycol or the monoethyl ether of ethylene glycol. On exposure to air the aqueous medium and the air-treating component gradually evaporate from the gel into the surrounding atmosphere. One feature of such gels, which is exhibited by most air-treating gels, is that they shrink with usage which is used to provide an indication of when they are no longer performing satisfactorily. Gels of the above type are described in U.S.

Specifications Nos. U.S. 2,691,615 and 2,927,055 and U.K. Specification Nos. 1,241,914; 1,438,098 and 1,448,318.

Water-based gels suffer from various disadvantages. For example the mechanical strength thereof is usually poor which necessitates elaborate support structures therefor. In addition the maximum volatile air-treating component content of such gels is quite low, in practice about 5%w which, together with the rapid evaporation of the aqueous medium, means that such gels have to be quite bulky in order to remain active for a reasonable period.

Another type of gel, known as soap-gels, are based on a soap, e.g. sodium stearate, as gelling agent, and the medium is usually an alcoholic medium although water may also be present. A soap gel, using ethyl or isopropyl alcohol as the alcoholic medium, in the form of an insect repellant stick, is described in U.S. Specification No. 2,465,470. However, a problem of using soap gels as air-freshening compositions is that many alcohols deteriorate the odour quality of the volatile air-treating component and/or provide an inadequate indication of when such gels are no longer performing satisfactorily.

The Applicants have now found that soap-gels which are at least partly based on monoalkyl ethers of alkylene glycols are excellent air-treating gels, in particular air-freshening gels. Such gels are much more rigid than water-based gels and therefore do not require elaborate support structures. Moreover they have good odour quality and also shrink with usage to provide an indication of when they are no longer performing satisfactorily. In addition they may contain a large amount of the volatile air-treating component, e.g. from 10 to 30%w, and are less bulky than water-based gels; for example the weight of the soap-gels of the present invention is about 10% of the weight of water-based gels having the same life.

Accordingly. the present invention provides an air-treating gel comprising a substantially rigid composition containing (I) a soap, (II) an alcoholic medium comprising a monoalkyl ether of an alkylene glycol, and (III) one or more volatile air-treating components.

Suitable soaps, which are the gelling agents, are the salts, in particular the alkali-metal salts, of Cs to C30 monocarboxylic acids, in particular of C12 to C20 monocarboxylic acids.

The monocarboxylic acids may be natural or synthetic, linear or branched, saturated or unsaturated, with linear saturated monocarboxylic acids being preferred. Particularly suitable soaps are the sodium salts of C14 to C18 monocarboxylic acids. The most preferred soap is sodium stearate.

Suitable monoalkyl ethers of alkylene glycols are the C1 to C4 monoalkyl ethers of mono-, di- and triethylene glycols. Such ethers may be represented by the general formula: R-O-CHrCH2(-O-CH2CH2)n-OH wherein R is a C1 to C4 alkyl group, and n is 0,1 or 2.

The preferred ether is the monoethyl ether of diethylene glycol which is commercially available as "Dioxitol" (registered Trade Mark). The ether may be the only component of the alcoholic medium or may be in admixture with water, preferably distilled water. If water is present then the amount thereof is suitably from 1 to 90%w, based on the weight of the ether.

Preferred air-treating gels are those comprising from 5 to 25%w, based on the weight of gel, of component (I) i.e. the soap, the balance being components (II) and (III). Suitably the weight ratio of component (II) to component (III) may vary from 1:5 to 10:1, preferably from 1:1 to 10:1.

The volatile air-treating component may be for example, an odorant, a pesticide, a bactericide or a fungicide. Examples of pesticides include the volatile organic phosphorous containing components. Preferably, the air-treating component is an odorant (in which case the gels are usually referred to as air-freshening gels), which may be a substance that emits a pleasant odour (a perfume) or a substance that destroys or masks obnoxious odours (a deodorant). Suitable perfumes include the perfumes known as HX 4530 and Everfresh (ex IFF, Holland.

The air-treating gels of the present invention may contain components in addition to those described above. Examples of such additives include dyes, anti-oxidants and fillers.

The air-treating gels may be prepared by any convenient technique such as by mixing the components and refluxing the mixture, with stirring for 10 to 60 minutes at a temperature of from 80 to llO"C until the soap completely dissolves. A gel forms upon cooling of the mixture. The mixture may be poured into a suitable container or mould to prepare a gel of any desired shape. The air treating gels may be positioned or supported within a holder.

The invention will be illustrated by reference to the following Examples.

Examples I to 7 Air-treating gels were prepared having the compositions described in the table.

Table Examples Components 1 2 3 4 5 6 7 (%w) Sodium stearate 20 15 15 15 10 10 15 Monoethyl ether of 55 65 50 55 65 60 diethylene glycol Monoethyl ether - - - - - - 50 of triethylene glycol water (distilled 5 - 15 20 10 - 15 perfume (Everfresh) 20 20 20 10 15 30 20 The air-freshener gels had excellent odour quality and shrank upon usage to provide an indication of when substantially all of the perfume had been emitted, although the gel of Example 7 was inferior in this latter respect. In addition the gels remained rigid at temperatures of up to at least 55"C.

WHAT WE CLAIM IS: 1. An air-treating gel comprising a substantially rigid composition containing: (I) a soap,

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (10)

**WARNING** start of CLMS field may overlap end of DESC **. (I) a soap, (II) an alcoholic medium comprising a monoalkyl ether of an alkylene glycol, and (III) one or more volatile air-treating components. Suitable soaps, which are the gelling agents, are the salts, in particular the alkali-metal salts, of Cs to C30 monocarboxylic acids, in particular of C12 to C20 monocarboxylic acids. The monocarboxylic acids may be natural or synthetic, linear or branched, saturated or unsaturated, with linear saturated monocarboxylic acids being preferred. Particularly suitable soaps are the sodium salts of C14 to C18 monocarboxylic acids. The most preferred soap is sodium stearate. Suitable monoalkyl ethers of alkylene glycols are the C1 to C4 monoalkyl ethers of mono-, di- and triethylene glycols. Such ethers may be represented by the general formula: R-O-CHrCH2(-O-CH2CH2)n-OH wherein R is a C1 to C4 alkyl group, and n is 0,1 or 2. The preferred ether is the monoethyl ether of diethylene glycol which is commercially available as "Dioxitol" (registered Trade Mark). The ether may be the only component of the alcoholic medium or may be in admixture with water, preferably distilled water. If water is present then the amount thereof is suitably from 1 to 90%w, based on the weight of the ether. Preferred air-treating gels are those comprising from 5 to 25%w, based on the weight of gel, of component (I) i.e. the soap, the balance being components (II) and (III). Suitably the weight ratio of component (II) to component (III) may vary from 1:5 to 10:1, preferably from 1:1 to 10:1. The volatile air-treating component may be for example, an odorant, a pesticide, a bactericide or a fungicide. Examples of pesticides include the volatile organic phosphorous containing components. Preferably, the air-treating component is an odorant (in which case the gels are usually referred to as air-freshening gels), which may be a substance that emits a pleasant odour (a perfume) or a substance that destroys or masks obnoxious odours (a deodorant). Suitable perfumes include the perfumes known as HX 4530 and Everfresh (ex IFF, Holland. The air-treating gels of the present invention may contain components in addition to those described above. Examples of such additives include dyes, anti-oxidants and fillers. The air-treating gels may be prepared by any convenient technique such as by mixing the components and refluxing the mixture, with stirring for 10 to 60 minutes at a temperature of from 80 to llO"C until the soap completely dissolves. A gel forms upon cooling of the mixture. The mixture may be poured into a suitable container or mould to prepare a gel of any desired shape. The air treating gels may be positioned or supported within a holder. The invention will be illustrated by reference to the following Examples. Examples I to 7 Air-treating gels were prepared having the compositions described in the table. Table Examples Components

1 2 3 4 5 6 7 (%w) Sodium stearate 20 15 15 15 10 10 15 Monoethyl ether of 55 65 50 55 65 60 diethylene glycol Monoethyl ether - - - - - - 50 of triethylene glycol water (distilled 5 - 15 20 10 - 15 perfume (Everfresh) 20 20 20 10 15 30 20 The air-freshener gels had excellent odour quality and shrank upon usage to provide an indication of when substantially all of the perfume had been emitted, although the gel of Example 7 was inferior in this latter respect. In addition the gels remained rigid at temperatures of up to at least 55"C.

WHAT WE CLAIM IS: 1. An air-treating gel comprising a substantially rigid composition containing: (I) a soap,

(II) an alcoholic medium comprising a monoalkyl ether of an alkylene glycol, and (III) one or more volatile air-treating components.

2. A gel as claimed in claim 1, wherein the soap is an alkali-metal salt of a C8 to C30 monocarboxylic acid.

3. A gel as claimed in claim 2, wherein the C8 to C30 monocarboxylic acid is stearic acid.

4. A gel as claimed in any one of claims 1 to 3, wherein the alcoholic medium comprises an ether of general formula: R - O - CH2 - CH2 (- O - CH2CH2)n-OH wherein R is a C1 to C4 alkyl group, and n is 0,1 or 2.

5. A gel as claimed in claim 4, wherein the ether is the monoethyl ether of diethylene glycol.

6. A gel as claimed in any one of claims 1 to 5, wherein the alcoholic medium also comprises water.

7. A gel as claimed in claim 6 wherein the water is present in an amount of from 1 to 90%w based on the weight of the ether.

8. A gel as claimed in any one of claims 1 to 7, wherein the amount of component (I) is from 5 to 25%w.

9. A gel as claimed in any one of claims 1 to 8, wherein the weight ratio of component (II) to component (III) is from 1:5 to 10:1.

10. A gel as claimed in claim 1, substantially as herein described with particular reference to any one of Examples 1 to 7.