NO138931B - GEL WITH AIR REFRESHING EFFECT. - Google Patents

Description

The present invention relates to an improved air freshening gel where an aqueous medium containing a volatile air freshening component is gelled using a new gelling

medium. More particularly, the invention relates to a new gelling agent preparation comprising carrageenan, locust bean gum and ammonium chloride, where the carrageenan contains at least 40% by weight of the kappa-carrageenan of the total carrageenan.

Air freshening gels and their gelling agents are well known. Air freshening gels usually comprise an aqueous medium containing a volatile air freshening ingredient and a gelling agent which gels the essentially aqueous medium. Air freshening gels are ideal means of freshening air and are popular consumer products.

Air freshening gels work by continuously releasing

make air freshening ingredients from the gel by room temperature evaporation of the aqueous medium inside the gel. The volatile air freshening ingredients may include disinfectants, bactericides, insecticides and scented materials, or oils that de-

gives a pleasant smell and/or reduces unpleasant smells.

According to US-PS 2,927,055 air freshening gels are to date

have been produced by using as gelling agent a mixture of carrageenan, locust bean gum and potassium chloride together with sodium carboxymethyl cellulose. According to the patent, the composition of the ingredients in the gelling preparation is indicated in % by weight of the total gel preparation as follows: 0.75 to 1.8% carrageenan, 0.2 to 0.75% locust bean gum, 0.1 to 0.75% potassium chloride and 0.15 to 0.7% carboxymethyl cellulose. According to US-PS 2,927,055, the air freshener gel is prepared by mixing the components of the gelling agent in the dry state, adding the mixed components to cold water and heating the components to 82-88°C with stirring until the solids are completely dissolved. The aqueous dispersion is then cooled to 77°C

and the pre-mixed air freshening ingredients are added with stirring until a uniform dispersion is formed, the dispersion is transferred to molds and cooled to form a shaped gel.

According to Canadian patent 895,825, air freshening gels can be prepared with gelling agents comprising mixtures of special carrageenan fractions, namely kappa and iota carrageenan. The Canadian patent specifically teaches the use of a gelling agent preparation in air freshening gels comprising kappa and iota fractions of carrageenan where the weight ratio between respective constituents lies between approx. 1.5:1 and approx. 7:1. The Canadian patent also teaches the optional addition of calcium and/or potassium ions in the form of their chlorides to the gelling agent preparation. The optional addition of calcium or potassium ions to the gelling agent according to the Canadian patent is particularly useful when the gelling agent contains high concentrations of kappa-carrageenan.

The air freshening gels obtained according to US-PS 2,927,055 and Canadian patent 895,825 have been found to exhibit undesirable gel syneresis, i.e. separation of the aqueous medium from the gel due to gel contraction and/or insufficient water gel strength.

It has now been found that gel syneresis problems associated with gelling agent combinations set forth in US-PS 2,927,055 and Canadian Patent 895,825 can be overcome by the improved gelling agent preparation according to the invention. It was unexpectedly found that the three-component gelling agent preparation according to the invention provides an air freshening gel which exhibits negligible syneresis and improved water gel strength when used for the production of air freshening gels.

According to the present invention, an improved air freshening gel is obtained which essentially consists of 1.5 - 4% of a gelling agent and 9 8.5 - 96% of an aqueous medium containing a volatile air freshening component. The gelling agent comprises: a carrageenan containing at least 40% by weight of the carrageenan in the form of kappa-carrageenan, in the range of from 0.6 to 2.0%, locust bean gum in the range of from 0.2 to 1.0%, and the characteristic is that it contains a water-soluble ammonium salt selected from ammonium chloride, ammonium sulfate, ammonium acetate, ammonium phosphate (dibasic) and mixtures thereof, in an amount of from 0.1 to 1.0%, where the percentages are percentages by weight of the air freshening gel. • Throughout the application and in the examples, all parts and percentages are parts and percentages by weight of total air freshening gel unless otherwise stated.

The new air freshening gel exhibits negligible

syneresis and improved water gel strength.

The term "carrageenan" is used here to denote a sulfated polysaccharide with at least 40% by weight of the carrageenan in the form of kappa-carrageenan, and the rest essentially in the form of lambda-carrageenan. Carrageenan can be obtained from a class of seaweed known as Rhodophyceae (red algae), subclass Florideae and order Gigartinales. Speci-

Alternatively, the carrageenan can be obtained from species within the families Gigartinaceae, Solieriaceae and Hypneaceae, Furcellariaceae and combinations thereof.

More particularly, the carrageenan can be obtained from the genera Gigartina, Chondrus, Eucheuma, Hypnea, Furcellaria and combinations thereof. Most spe-

Alternatively, the carrageenan according to the invention can be obtained from extracts of Gigartina stellata, Chondrus crispus, Chondrus ocellatus, Eucheuma cottonii, Hypnea musciformis, Furcellaria fastigiata and combination

is hence. The ideal is that the carrageenan according to the invention is obtained from Chondrus crispus (Irish moss), Furcellaria fastigiata and Hypnea musciformis.

The sulfated polysaccharides in the present invention

are well known in the art and are more fully discussed in the following publications: "Polysaccharide Gels" by Reese, D.A., Chemistry and Industry, vol. 19, p. 630 (1972).

Lerring, T., Hoppe, H.A., Schmid, 0.J., Marine Algae,

p. 342, Cram, DeGruyter & Co. (1969).

Carrageenan can be extracted from

dried seaweed by first washing the dried seaweed with water, extracting the washed seaweed at alkaline pH, removing the residue by filtration,

dry the extract and grind the dried carrageenan extract. Any commercially available carrageenan which contains at least 40% by weight of the carrageenan as kappa-carrageenan, obtained from the genera and species mentioned above can be used in the gelling agent according to the invention.

The locust bean gum is

easily available and usually contains approx. 88% D-galacto-D-mannoglucan, 4% pentane, 6% protein, 1% cellulose and 1% ash. John's wort gum is also known by other names such as e.g. carob gum,

gatto gum, hevo gum, janda gum, lackey gum, Rubigum, Lupogum, Luposol, Tragon gum, Tragarab and Tragasol. Locust bean gum is chemically characterized as a neutral polysaccharide with a main content of D-galacto-D-mannoglucan.

The most preferred ammonium salt is ammonium chloride. The ammonium chloride is usually added to the gelling agent preparation

in dry form. Any commercially available ammonium chloride,

i.e. of technical or reagent grade, can be used in the new gelling agent preparation according to the invention.

The gelling agent preferably comprises the carrageenan containing at least 40% by weight of the carrageenan as kappa-carrageenan in the range of from 1.0 to 1.8%/locust gum in the range of from 0.4 to 0.8% and a water-soluble ammonium salt selected from ammonium chloride , ammonium sulfate, ammonium acetate, ammonium phosphate (dibasic) and mixtures thereof, said salt being present in a concentration in the range from 0.5 to 1.0%. Most preferably, the gelling agent according to the present invention comprises approx. 1.5% carrageenan which contains at least 40% by weight of the carrageenan as kappa-carrageenan, approx. 0.6% locust bean gum and approx. 0.75% ammonium chloride.

The above-described ranges indicated for the components of the new gelling agent according to the invention have been found necessary to obtain air freshening gels which exhibit negligible syneresis, improved water viscosity and water gel strength.

However, the respective ranges of the constituents of the gelling agent preparation may be varied within the above ranges to provide air freshening gels exhibiting different degrees of water viscosity, water gel strength and syneresis, which may be desirable for particular applications.

In the composition of air freshening gels, the gelling agent comprises from 1.5 to 4% of the total air freshening gel, while the aqueous medium containing an air treatment component comprises the remaining 98.5 to 96%. The air treatment components make up from 2 to 10% of the aqueous medium.

By "air treatment ingredient" is meant perfumes, bactericides, essential oils, fungicides or other desirable air treatment ingredients or mixtures thereof. The air treatment ingredients are preferably a volatile material at room temperature, compatible with the other ingredients in the air freshening gel and dispersible in the aqueous medium. Oils that can be used to cover up bad odors can be used, e.g. rose oil, orange oil, pine oil, lemon oil, spearmint oil, wintergreen oil, cedar oil, Canadian fir oil and the like. The above-mentioned oils can also be used in combination with good-smelling substances such as e.g. aromatic esters, aldehydes, ketones and other compounds known to those skilled in the art when it comes to mixing fragrant substances.

The aqueous medium in the air-freshening gel may also contain carriers that provide increased solubility for the special oils or fragrant substances to be used in the aqueous medium in the air treatment gel. The carriers can be present in the aqueous medium in the air freshening gel in the range of from approx. 2 to approx. 6%. Typically, the carriers include ethanol, isopropanol, ethylene glycol, propylene glycol, hexylene glycol, cellosolve or the like.

The aqueous medium in the air freshening gel may also contain bactericides or fungicides to prevent microbial or fungal growth inside the air freshening gel. The bactericides or fungicides can be present in the aqueous medium in the air freshening gel in an amount of from approx. 0.001 to approx. 0.01%. Typically, the bactericide or fungicide comprises sodium benzoate, methyl, butyl or propyl parahydroxybenzoate, mixtures thereof and the like.

The aqueous medium in the air-freshening gel can also contain water-soluble or oil-soluble dyes which can give color to the air-freshening gel. In particular, the water-soluble or oil-soluble dyes can be present in the aqueous medium in the air freshening gel in an amount of up to approx. 0.05%. Typical examples of suitable water-soluble or oil-soluble dyes are Rose Bengal dye, Uramine dye, Rhoda-mine dye and the like.

The aqueous medium in the air freshening gel may also contain emulsifiers which are well known in the field. The emulsifiers can be anionic, such as e.g. the alkyl sulphonates, the alkyl sulphates or the alkyl ether sulphates, or they can be non-ionic compounds such as e.g. the polyethoxylates, the sorbitan esters or the polyethoxylates of the sorbitan esters.

The air-freshening gels according to the invention are typically produced as follows: dry mixing of the gelling agent components, i.e. carrageenan, locust bean gum and ammonium chloride, dispersion of the dry-mixed gelling agent components in water at a temperature below approx. 32°C with stirring, heating the dispersed gelling agent to a temperature between approx. 66 and approx. 88°C with stirring until the dispersed gelling agent is completely dissolved, cooling the aqueous solution of the gelling agent to a temperature between approx. 57 and approx. 66°C, adding an air conditioning agent to the cool solution of the gelling agent with stirring to provide a uniform mixture of air freshening ingredients and cooling to a temperature below approx. 38°c to cause gel formation and thus provide the air freshening gel. The dispersed gelling agent is preferably heated to a temperature of approx. 82°C with stirring until the solids are completely dissolved. It is also preferred that the uniform mixture of air freshening gel is poured into a suitable container or mold to give a gel of the desired shape.

The new gelling agent according to the invention is further illustrated by the examples that follow. All parts and percentages are by weight unless otherwise stated.

Example 1

The air freshening gel can be produced with the new gelling agent preparation according to the invention as follows. 500 grams of air freshening gel was prepared by first dry mixing 7.5 grams of carrageenan, 3.0 grams of commercial locust bean gum and 3.75 grams of reagent grade ammonium chloride. The carrageenan mainly comprises kappa-carrageen, i.e. 70-80% kappa-carrageen and 20-30% lamda-carrageen. The carrageenan used in this example was purchased from Stauffer Chemical Company as an extract of chondrus crispus (Irish moss).

The dry mixed gelling agent was then dispersed

for about. 440 grams of water with stirring. The dispersed gelling agent was then heated to a temperature of approx. 82°C with stirring until the dispersed solids were dissolved. The gelling agent solution was then allowed to cool to approx. 66°C. The weight of the gelling agent solution was adjusted to 460 grams by adding water. It was then added to the gelling agent solution at a temperature of approx. 66°C, 40 grams of the air conditioner comprising 6.6 grams of lemon oil, 3.3 grams of orange oil, 20 grams of isopropyl alcohol, 10 grams of ethylene glycol and 0.1 gram of Uramine dye. The air conditioning agent was then mixed to provide a uniform air freshening dispersion. The air freshening dispersion was then poured into crystallization dishes 7.0 cm in diameter and 5.0 cm in height. The air freshening dispersion was then allowed to cool to room temperature so that an air freshening gel was obtained.

Syneresis of air freshening gels was determined as follows: The air freshening gel crystallization dish was covered with paraffin paper and kept in a constant temperature incubator at

4°C. After overnight incubation, the air freshening gel was removed from the incubator and allowed to equilibrate to room temperature. The paraffin paper was then removed from the air freshening gel and the gel carefully tapped into a pre-weighed paper towel. The air freshening gel was then moved around on the paper towel to allow the paper towel to absorb excess liquid from the gel. The weight of the air freshening gel and the weight of the paper towel were then determined. Percent syneresis is expressed as the amount of liquid absorbed by the paper towel, divided by the total gel weight, multiplied by 100.

The air freshening gel sample from example 1 was found

to exhibit a degree of syneresis of less than 0.3%, when determined as described above. The air freshening gel that was developed

prepared according to Example 1, showed no visible syneresis. Air freshening gels which therefore exhibit less than 0.3% syneresis, determined as described above, exhibit negligible syneresis, i.e. no free-flowing liquid can be seen.

The water viscosity of the air freshening dispersion

was determined as follows, the water viscosity of the air freshening dispersion was determined at 63°C with a Brookfield viscometer, model LVT, using the appropriate spindle and rotation speed. The water viscosity of the air freshening dispersion was 1100

centipois, determined as above described.

The water gel strength of the air freshener gel was determined in a gel tester, Model GT-3 from Marine Colloids Inc. For the gel tester, a flat piston having a diameter of 1.1 cm was used. A dietetic scale was placed directly under the plunger and was used to measure the breaking strength required for the plunger to penetrate the material to be measured. After the syneresis calculation, the air freshening gel was placed in a crystallization dish. The water gel strength was then determined by placing the crystallization dish containing the sample of the air freshening gel to be determined on top of the scale. The scale was then set to zero and the flat plunger brought into contact with the surface of the gel material. The plunger was continuously pressed into the gel until the maximum force required to break the gel surface was indicated. The weight indicated on the scale and required to break the gel surface for the sample in Example 1 was 710 grams.

The composition of the air freshening gel prepared according to Example 1 is given in Table I. The results of the evaluation of the air freshening gel in terms of water viscosity, water gel strength and syneresis are shown in Table VI-

Example 2

This example represents a control sample of air freshening gel prepared in accordance with Example 1 of US-PS 2,927,055. The air freshening gel was produced according to the method described for example 1 in the present application. The

the air freshening gel preparation is presented in Table II.

The water viscosity, water gel strength and syneresis were determined as described above in Example 1. The results of the determinations of water viscosity, water gel strength and syneresis for the air freshener

the gel is shown in Table VI.

v Example 3

An air freshening gel was prepared in accordance with Example 1 of Canadian Patent No. 895,825. The air freshening gel was prepared using the method set out in Example 1. The composition of the air freshening gel is set out below in Table III.

The air freshening gel prepared in accordance with example 3 was determined with regard to water viscosity, water gel strength and syneresis according to the methods indicated in example 1. The results of the determination of the air freshening gel are shown in table VI.

Example 4

An air freshening gel was prepared with the composition set forth in Example 2 of Canadian Patent No. 895,825. The procedure for making the air freshening gel was

as indicated in Example 1 above. The composition of the air freshening gel is given in Table IV.

The air freshening gel prepared as described above was determined with regard to water viscosity, water gel strength and syneresis. The results of the determinations are shown in Table VI.

Examples 5-9

In examples 5-9, air freshening gels were prepared according to the method indicated in example 1 above. The gelling agent preparations were varied as indicated in Table V below. The air freshening gels prepared in accordance with Examples 5-9 were determined for water viscosity, water gel strength and syneresis as previously stated in Example 1. The results of these determinations are set forth in Table VI.

Examples 10 and 11

In example 10, an air freshening gel was prepared with the carrageenan obtained from chondrus crispus containing approx. 80% by weight of the carrageenan as kappa-carrageenan. The composition of the air freshening gel is set out in Table V. The procedure for producing the air freshening gel in this example was as set out in example 1 above.

In example 11, an air freshening gel was prepared with a polysaccharide extract from Hypnea musciformis corresponding to carrageenan. The composition of the air freshening gel produced with this particular gelling agent combination is set out in Table v. The procedure for producing the air freshening gel in this example was as set out above in example 1.

Examples 10 and 11 were determined with respect to water viscosity, water gel strength and syneresis as indicated above in Example 1. The results of these determinations are shown in Table VI.

It is clear from table VI in relation to examples 1-4 that the air freshening gel produced with the new gelling agent preparation according to the invention exhibits improved physical properties, the syneresis level being below 0.5%, the water gel strength being above 400 grams and the water viscosity being below 2,700 centipoises. In contrast, it is apparent from Table VI, Example 2 that air freshening gels prepared in accordance with US-PS 2.92 7.055 where gelling agents are used comprising carrageenan, locust bean gum, potassium chloride and carboxymethyl cellulose, exhibit an undesirable level of syneresis, i.e. 0.67% . It is also apparent from Table VI, Example 3, which represents an air freshener gel prepared in accordance with Example 1 of Canadian Patent No. 895,825, where an air freshener gel is prepared with a gelling agent comprising kappa-carrageenan and iota-carrageenan, that the water gel strength of the air freshener gel is unwanted, i.e. 88 grams. In terms of water gel strength, it has been found that air freshening gels exhibiting water gel strengths below approx. 400 grams is undesirable because the gel is not able to retain its original shape. Furthermore, it is apparent from Table VI, Example 4, which represents an air freshener gel prepared in accordance with Example 2 of Canadian Patent No. 895,825, where a gelling agent comprising .kappa-carrageenan, iota-carrageenan and calcium chloride is used, that the air freshener gel exhibits undesirable water gel strength, i.e.

87 grams.

It is clear from Table VI, examples 5-9, that air freshening gels can be prepared with the new gelling agent preparation according to the invention, i.e. carrageenan, locust bean gum and ammonium chloride. The level of syneresis, water gel strength and water viscosity as indicated in Table VI is well within the desirable limits required for these determination parameters.

It is clear from Table VI, Examples 10 and 11, that air freshening gels exhibiting desirable water viscosity, water gel strength and syneresis properties can be prepared with gelling agents mainly containing kappa-carrageenan, as indicated by Example 10 and a polysaccharide extract from Hypnea musciformis.

Variations can be made in terms of quantities, methods and materials without deviating from the scope of the invention as defined in the subsequent claims.

Comparative experiments have been carried out to illustrate the difference between a gel with a gelling agent containing ammonium chloride and one containing potassium chloride instead of ammonium chloride.

Air freshening gels were produced according to the method described in the second entire section on page 6. This method is essentially the same as that described in US patent 2.9 27.055. The sodium carboxymethyl cellulose, which is indicated as a component in the system according to US patent 2,927,055, was not used.

The amount of materials used in the examples,

are indicated in Table VII. The carrageenan used was calcium carrageenan unless otherwise stated. In addition to the carrageenan, locust bean gum and chloride salt in the amounts listed in Table VII, each sample also contained 2.0% rose oil, 4.0% isopropyl alcohol, 2.0% ethylene glycol, 0.02% Rose Bengal dye and sufficient water to bring the entire mixture to 100%.

The air freshening gels were examined with regard to gel syneresis, water viscosity of the air freshening dispersion and water gel strength of the air freshening gel. These three factors were determined by the examination methods indicated above, respectively in the 1st full paragraph page 7, the paragraph connecting pages 7 and 8 and the 1st full paragraph on page 8, with the exception of the crystallization bowl mentioned in connection with the water gel strength on page 8, lines 8 and 9, was a petri dish.

The comparative results between air freshening gels prepared with ammonium chloride according to the invention and potassium chloride as known from the prior art, at different concentrations and different amounts of carrageenan, locust bean gum and chloride salt are given in the following Table VII:

These data show that the use of ammonium chloride instead of potassium chloride leads to a reduction in the percentage of syneresis in air freshening gels.

The same effect is achieved using potassium carrageenan (a carrageenan prepared using potassium chloride in the washing step and lime in the extraction step so that the potassium ion is the dominant cation, with calcium and sodium present in smaller amounts). The same methods and additional ingredients as described above were used. The results are reproduced in table VIII.

The results obtained with different samples of the carrageenan can be compared with each other. Certain deviations in the results from different days are possible due to variation in the carrageenan used.

These data show that of all the samples, both of the gels according to the invention and the known gels, which passed the requirements mentioned at the top of page 14 for water viscosity (below 2700 centipoise) and water gel strength (above 400 g), only those samples which was prepared with ammonium chloride, which passed the requirements set for syneresis.

Claims (2)

1. Air freshening gel consisting mainly of 1.5 to 4% of a gelling agent and 98.5 to 96% of an aqueous medium containing a volatile air freshening component, where the gelling agent comprises a carrageenan containing at least 40% by weight of the carrageenan in the form of kappa- the carrageenan, said carrageenan being present in a concentration in the range from 0.6 to 2.0%, and a locust bean gum in a concentration in the range from 0.2 to 1.0%, characterized in that the gelling agent also comprises a water-soluble ammonium salt which is ammonium chloride, ammonium sulphate, ammonium acetate, ammonium phosphate (dibasic) or mixtures thereof, said salt being present in a concentration in the range of from 0.1 to 1.0%, where said percentages are weight percentages of said air freshening gel. 2. Air freshening gel according to claim 1, where said gelling agent comprises carrageenan in a concentration in the range of from 1.0 to 1.8%, and a locust bean gum in a concentration in the range of from 0.4 to 0.8%, characterized by that the water-soluble ammonium salt is present in a concentration in the range from 0.5 to 1.0%.