FIELD OF THE INVENTION The current invention pertains to an improvement of gel-like deodorizing agents for household use, in particular to air fresheners.

BACKGROUND OF THE INVENTION Air Fresheners are a commonly used means for deodorizing rooms to avoid unwanted odor. Such air fresheners may comprise a liquid, gel-like or solid composition, containing a perfume, which will evaporate into the air. One major problem in this regard is the rate of evaporation. If this rate is too high, the air freshener will quickly lose its capability to deodorize the air, which is not acceptable for the user. On the contrary, a slow rate of evaporation may cause too low a level of perfume in the air, which is also detrimental to the expectations of the customers. The problem of high evaporation rates is critical in particular with any liquid or gel-like compositions. Therefore, there is a constant need to provide perfume compositions, preferably in gel-form, which have an improved evaporation rate. BRIEF SUMMARY OF THE INVENTION

It was a primary target of the present invention to provide a method to enhance the life time of air freshener gels. The length of life of an air freshener is significantly increased by slowing the evaporation rate of the gel. An additive comprising a blend of alkoxylated partial fatty acid esters of glycerol and alkoxylated glycerol was identified, that when added to a regular gel formula extends the life of the gel by 2 to 3 times. Other aspects of the invention will become apparent from the detailed description which follows. P2011/003208

BRIEF DESCRIPTION OF THE DRAWING

Figure 1 shows a graph of air freshener longevity, recorded as weight remaining versus time in days, for a composition of the invention compared with a control composition.

DETAILED DESCRIPTION OF THE INVENTION

The invention is characterized by adding a selected additive to a gel-formulation containing a volatile substance to decrease the evaporation of the volatile substance from the gel.

Gel-like air fresheners are known to the skilled person, for example from US 4, 178,264, pertaining to air- freshener gels, comprising carrageenan and a stearate salt as gelling or thickening agent. The compositions used in air- fresheners according to the current invention are aqueous gels. A gel in general is a jelly-like material that can have properties ranging from soft and weak to hard and tough. Gels are defined as a substantially dilute cross-linked system, which exhibits no flow when in the steady-state. By weight, gels are mostly liquid, yet they behave like solids due to a three-dimensional cross-linked network within the liquid. It is the cross- linking within the fluid that gives a gel its structure (hardness) and contributes to stickiness (tack). In this way gels are a dispersion of molecules or particles within a liquid in which the solid is the continuous phase and the liquid is the discontinuous phase.

To obtain an aqueous gel it is necessary to combine the water with a substance, called "gellants" or "thickeners" which have the capability to create such a cross-linked structure. In particular such gellants are preferably selected from polymeric compounds, either of natural or synthetic origin. Polymeric gellants or thickeners could be selected from cationic, anionic or nonionic polymers. Also amphoteric polymers could be used. Preferred polymeric agents are cross-linked polyacrylic acid-type thickening agents. As used herein the term "polyacrylic acid-type" refers to water-soluble homopolymers of acrylic acid or methacrylic acid, or water-dispersible or water-soluble salts, esters or amides thereof, or water-soluble copolymers of these acids of their salts, esters or amides with each other or with one or more other ethylenically unsaturated monomers, such as, for example, styrene, maleic acid, maleic anhydride, 2-hydroxyethylacrylate, acrylonitrile, vinyl acetate, ethylene, propylene, and the like.

These homopolymers or copolymers are characterized by their high molecular weight, in the range of from about 500,000 to 10,000,000, preferably 500,000 to 5,000,000, especially from about 1 ,000,000 to 4,000,000, and also by their water solubility, generally at least to an extent of up to about 5 percent by weight, or more, in water at 25 °C.

These thickening agents are used in their lightly cross-linked form wherein the cross- linking may be accomplished by means known in the polymer arts, as by irradiation, or, preferably, by the incorporation into the monomer mixture to be polymerized of known chemical crosslinking monomeric agents, typically polyunsaturated (e.g. diethylenically unsaturated) monomers, such as, for example, divinylbenzene, divinylether of diethylene glycol, Ν,Ν'-methylene-bisacrylamide, polyalkenylpolyethers (such as described above), and the like. Generally, those skilled in the art will recognize that the degree of cross-linking should be sufficient to impart some coiling of the otherwise generally linear polymeric compound while maintaining the cross-linked polymer at least water dispersible and highly water- swellable in an ionic aqueous medium. Further suitable types of gellants or thickeners are selected from polysaccharides like starches, vegetable gums, and pectin, or proteins. Preferred polysaccharide gellants are selected from the group alginic acid, agar and carrageenan.

The gels which are commonly used as air-fresheners contain gellants or any mixture of different gellants, in amounts of 0.5 to 25 wt%, preferably of 1.0 to 10 wt% and most preferred from 1.5 to 5 wt%, based on the weight of the gel. For the sake of clarity, it should be stated that the gels according to the invention show their gel-properties at room temperature (21 °C) at normal pressure.

The gels contain water, wherein amounts of at least 75 wt%, or 85 wt% and more are common. A preferred range is from 85 to 98 wt% or from 90 to 96 wt% of water, based on the total weight of the gel. It is possible and preferred to use deionized or distilled water, but also tap water may be sufficient to provide the air-freshener gels.

Furthermore, the gels contain a volatile substance, preferably selected from perfumes or fragrances. It is possible to select water-soluble and water-insoluble perfumes or fragrances or mixtures thereof. If water insoluble perfumes are used, the presence of emulsifiers or solubilizers is necessary.

The core aspect of the present invention pertains to the additive, which is a blend of alkoxylated partial fatty acid esters of glycerol and alkoxylated glycerol. The fatty acid portion of the ethoxylated glycerol esters are preferably selected from saturated or unsaturated, linear or branched carboxylic acids with 8 to 22 C-atoms. Preferred acids contain from 10 to 18, and more preferably from 12 to 14 C-atoms. Acid mixtures, such as coconut carboxylic acids may be used with advantage.

Such blends could be prepared by reacting glycerol fatty acids with alkoxylates. _^ or glycerol alkoxylates with fatty acids _i in the presence of catalysts, and under conditions well known to the skilled persons. The term "alkoxylates" in the sense of the present invention means either ethylene oxide or propylene oxide. In a preferred embodiment the glycerol alkoxylates contain only ethylene oxide moieties, however, mixed alkoxylates, containing both, ethylene oxide and propylene oxide (random or block-wise added) are also suitable.

It is preferred to use such glycerol alkoxylates which contain from 2 to 20, preferably 3 to 9 moles of ethylene oxide or propylene oxide or both per mol of glycerol esters or moles of glycerol. In a preferred embodiment the blend contains the alkoxylated partial fatty acids esters of glycerol and the alkoxylated glycerol in a weight ratio of 10 : 1 to 1 : 10, preferably 3 : 1 to 6 : 1 , and most preferably about 1 : 1. The blend may further optionally also contain alkoxylated fully esterified glycerol and/or glycerol.

Those blends are well known, for example from European patent application number 1 106 675, the contents of which is hereby incorporated by reference. According to the teaching of this reference those blends contain

46 - 90 wt% of alkoxylated monoester,

9 - 30 wt% of alkoxylated diester, and

1 - 15 wt% of alkoxylated triester,

and may be used in the method of the present invention with advantage. The blends will be used in small amounts, preferably in the range from 0.5 to 5.0 wt% or more preferred from 1.0 to 2.0 wt%, based on the weight of the total gel.

Such additives are commercially available, for example, Cetiol ^® HE from the applicant, which is a preferred additive for use according to the present invention.

The air freshener gel may contain small amounts of various optional ingredients. Such optional ingredients may include up to about 3.0 percent of silicone emulsion, up to about 3 percent of nonionic emulsifiers, up to about 1 percent of preservative and up to about 1 percent of pigment dispersions or water soluble dyes, as well as bacteriostats and the like. Furthermore, other common additives may be present, including dyes, organic or inorganic salts and/or pH-regulating agents. These additives may be present, if desired, in amounts from 0.5 to 5 % by weight.

The use of one or more non-aqueous solvents is also possible. Such solvents are selected for example from short chain alcohols, including, but not limited to ethanol propanol, isopropanol, butanol, isobutanol, and glycol solvents, such as ethylene glycol, propylene glycol, and the like. Such solvents may be present in amounts of 1 to 15 wt% based on the weight of the gel. The preparation of the gels is possible using various means and methods known to those skilled in the art. The blend of glycerol derivatives according to the invention is added during or after the manufacturing process to obtain the desired effect. A further embodiment of the invention pertains to an aqueous gel composition, containing a gellant and at least 0.5 to 5.0 wt%, based on the total weight of the composition of a blend of ethoxylated partially esterified glycerol, and ethoxylated glycerol as described above.

EXAMPLES

Two gel air freshener compositions have been prepared, one (Test) containing the inventive additive, the other one without it (Control). As gellant, a polysaccharide- comprising additive has been used.

Current gel formula (Control) Improved gel formula (Test)

% t %wt

Water 95.0 94.0

Gellant 2.0 2.0

Solvent 2.5 2.5

Fragrance 0.5 0.5

Cetiol ^® HE - 1.00

Weight loss data was measured over time (see Figure 1). Samples were stored at 23°C, 75% relative humidity. After 15 days, the control had lost 76.4% of its weight due to evaporation, while Test, with 1% wt. Cetiol ^® HE, had lost only 49.2%. The control weight remaining after 6 days was less than the Test weight remaining after 15 days. Therefore, the longevity of the control formulation is more than doubled when 1 % wt. Cetiol ^® HE is added.