SK154894A3 - Homogeneous isotropic cleaning mixture - Google Patents

Abstract

The invention provides a homogeneous, aqueous, cleaning composition which comprises surfactant and solvent, and is characterized in that it forms a solvent-water emulsion on evaporation of at least a portion of the solvent. In such systems the solvent system is selected such that it comprises: a first solvent component in an amount such that it is present at a level above the miscibility limit of that component with water, and, a second solvent component which is sufficiently volatile that, in use, it evaporates from the composition to leave a mixture of the first solvent component and water, said second solvent component being present at a level such that first solvent component is solubilised in the composition. By using the second solvent to assist in the solution of the first solvent it is possible to obtain compositions which are clear, stable, isotropic compositions. In use, the second, volatile solvent component evaporates from the overall composition and the remaining first solvent component and water phase-separate, thus forming an emulsion, whereby the cleaning action of the first solvent component is potentiated. The emulsion formed generally has a coarse dispersed phase. This yields the advantages of a stable non-emulsion product as regards storage, dosing and manufacture, employs a relatively low level of solvent and provides the cleaning benefits of a free-solvent system.

Description

Many cleaning compositions for use in the cleaning of hard surfaces in the home and industry contain, in addition to surfactants, solvent components. These solvents are generally intended to improve cleaning performance by cooperating in the removal of greasy or waxy contaminants. The advantages associated with the presence of solvents in such compositions are particularly significant at low levels of surfactant contents, such as in high-reflectance cleaning compositions, where high levels of surfactant residues cannot be tolerated.

Many of these solvent components are immiscible with water or have a relatively low level of miscibility above which they form emulsions, and therefore these compositions that contain solvent levels above the miscibility threshold must either be vigorously mixed prior to use or the solvent should be present as a stable emulsion.

One such emulsion is described in US 4689168 (The Drackett Company) which discloses an anisotropic hard surface cleaning composition that contains volatile silicones, a nonvolatile surfactant preferably selected from anionic, nonionic surfactants and mixtures thereof, and a polar organic solvent, which has a boiling point in the range of 75 to 250 ° C, which is preferably ethanol, propanol or butanol and water.

By shaking these components, semi-stable emulsions are formed which break in contact with the hard surface and release the components.

Stable emulsions are difficult to prepare and tend to phase separation. Since the consumer prefers stable, single-phase systems and single-phase systems are easier to prepare, process, store and dispense than emulsions, the use of immiscible solvents in single-phase mixtures has been limited to relatively low contents.

Compositions containing binary solvent systems of terpenes and polar solvents are described in EP 0040882 and EP 0080749.

Typical glass cleaning compositions are described in EP 261874 (The Procter and Gamble Company: 1986/87). Described herein are cleaning compositions comprising a specific isomer of n-butoxypropan-2-ol, commercially available as DOVANOL PnB (RTM, from DOV Chemical Company). n-butoxypropan-2-ol is miscible with water to a content of about 6% depending on temperature and isomer levels. It is stated herein that the use of sprays to apply the composition to the surface is unsuitable for odor problems.

A similar later application EP 0428816 (P&G: 1989/90) describes, in general terms, formulations containing, as a first solvent, from 1 to 9% ethanol, 0.5 to 3% n-butoxypropan-2-ol, 0.5 to 3% n-propoxypropanol as the second solvent 0.5 to 3% of a primary or secondary monoalcohol having a five carbon alkyl chain.

Other systems contained emulsions. GB 2144763 (P&G: 1983) relates to hard surface cleaners in the form of a so-called microemulsion of a solvent containing at least 5% solvent and a magnesium salt. The use of microemulsions was considered to be advantageous for the increased cleaning effect of the free solvent compared to solvent solutions in water or other aqueous media. Microemulsions are described herein as very fine emulsions that appear to be homogeneous mixtures.

Similar emulsion systems are described in EP 0347110 (Colgate: 1988) concerning pure liquid detergents containing anionic and nonionic surfactants, a polar solvent consisting of C 1 -C 4 alkyl ethers of ethylene or diethylene glycol, mono-, di- or tripropylene glycol and 2.5 to 5% fragrances at a pH of 6-7. The latter document also discusses the effect of magnesium on enhancing detergency in formulations containing anionic surfactants.

WO 80/02693 discloses mixtures of ethyl acetate, glycerol and water with an optional surfactant in mixtures that are normally biphasic systems in addition to the narrow formulation composition.

EP 105063 describes cleaning compositions comprising a basic solvent and, if necessary, a co-solvent which is used to solubilize the main solvent. The examples of EP 105063 use, as a water miscible solvent, diethylene glycol mono-n-butyl ether (commercially available as BUTYL DIGOL (TM)).

US-A-4212758 discloses a detergent comprising water-soluble components isopropanol and 1,2-propanediol together with oleic acid and water-insoluble ethyl acetate.

US-A-3764544 discloses the use of ethyl acetate or other similar acetates as an ester solvent in combination with a binding agent, for example, a glycol ether.

Despite the research conducted in this area, numerous technical problems remain.

When microemulsions are used, they are difficult to manufacture, but if not used, there may be a lack of solvent in the system to achieve effective purification.

In addition, the use of certain surfactants may lead to a product that is unstable or becomes so after a relatively short storage time. These products can be thrown away by consumers, releasing their sense of release of surfactants and solvents into the environment.

In addition, the normal use of surfactant / solvent cleaning compositions will increase the environmental burden of solvents and surfactants.

It is therefore desirable to ensure that surfactants released into the environment are readily biodegradable and it is advantageous to consistently use environmentally beneficial surfactants in cleaning compositions. Unfortunately, it has been found difficult to prepare homogeneous solvent-containing systems containing these surfactants.

Furthermore, the use of lower rather than higher solvent contents is advantageous as this reduces both the cost and the amount of solvent released into the environment. However, as mentioned above, the use of low levels of solvent can give poor cleaning results.

It is clear from the above that it is desirable to provide stable, biodegradable products that contain relatively low solvent levels and that provide an effective cleaning effect associated with a higher solvent level.

SUMMARY OF THE INVENTION

Systems containing a solvent and a surfactant have been proposed which decompose into emulsions in use.

Accordingly, the present invention provides a cleaning composition homogeneous, isotropic, containing solvent, wherein the solvent system comprises:

(a) the first solvent component in such an amount that it is present at a level above the water miscibility limit of that solvent component; and

b) a second solvent component in an amount such that the first solvent component is solubilized in a mixture characterized in that said first solvent component is selected from glycol ethers and said second solvent component is sufficiently volatile to evaporate said second component in use from the mixture leaving a solvent-water emulsion comprising the first solvent component and water.

By using a second volatile solvent to aid in the dissolution of the first solvent, it is possible to obtain compositions that are pure stable isotropic compositions and do not form microemulsions. When using the product, the second solvent is evaporated from the total mixture and the remaining first component and the aqueous phase are separated to form an emulsion, thereby condensing the cleaning ability of the first solvent component. The emulsion thus formed is generally coarsely dispersed. This provides the advantages of a stable, non-emulsion product in terms of storage, dosing and manufacturing, uses relatively low levels of solvent content, and provides the cleaning benefit of a solvent-free system.

First solvent

The presence of the first solvent component in an amount such that its content is above the miscibility limit of said solvent component in water is an essential feature of the invention.

Preferably, the first solvent component is selected from the group consisting of propylene glycol mono-n-butyl ether, dipropylene glycol mono-n-butyl ether, propylene glycol mono-t-butyl ether, dipropylene glycol mono-t-butyl ether, diethylene glycol, and mixtures thereof.

Most preferably, the first solvent component is propylene glycol mono-n-butyl ether (n-butoxypropan-2-ol), preferably present at a level of 6% to 12%.

Second solvent

The presence of a second volatile solvent component is an essential feature of the invention.

Preferably, the second solvent component is selected from volatile alcohols; miscible with water volatile glycol ethers, aldehydes, ketones, dialkyl ethers and mixtures thereof.

More preferably said second solvent component is selected from the group consisting of: methanol, ethanol, isopropanol, ethylene glycol monobutyl ether, and mixtures thereof.

Most preferably, the second solvent component comprises ethanol, isopropanol, and mixtures thereof. Ethanol in the form of technical methylated spirit is suitable for the practice of the present invention.

Surfactants

Surfactants are optional ingredients of the compositions of the invention, although it is desirable that the compositions of the invention further comprise one or more surfactants.

The type of surfactant is not critical to the general function of the invention.

In embodiments of the invention, the surfactants are generally anionic or nonionic, although it is contemplated that cationic, zwitterionic and amphoteric surfactants may be used. Mixtures of both anionic and nonionic surfactants may be used.

In particularly preferred embodiments of the invention, the cleaning compositions further comprise an anionic surfactant. It is contemplated that a wide range of anionic surfactants may be used in embodiments of the invention, some of which are listed below. In any case, the anionic surfactant will be present together with a suitable counter ion.

Preferably, the compositions further comprise magnesium ions in an amount corresponding to at least 0.02 M, where M is the molar amount of anionic surfactant in the composition.

The magnesium salt of the anionic synthetic detergent used in the invention may byf magnesium salt of a well known type of anionic detergent surfactants, e.g., C ^ g alkyl benzene sulfonates QC ^, C ^ g ^ QC alkane sulfonates, sulfonated ^mastn s acid esters, ^C 10 ~ ^C 18 are olefin sulfonates, di-C 1 -C 6 alkyl) sulfosuccinates, C 1 -C 18 alkyl sulfates, C 1 -C 16 alkyl ether sulfates containing from 1 to 10 moles of ethylene oxide. Further examples can be found in Schwarz-Perry Surface Active Agents and Detergents, Vol.

I (1949) and Vol. II (1958).

Especially preferred among the anionic detergents are magnesium salts of primary alcohol sulphates. These are considered to be more readily biodegradable than other surfactants and are available in commercial quantities from renewable sources.

Primary alcohol sulphates are mixtures of materials of the general formula:

Rosa ₃ X wherein R is a Cg-C ^ g primary alkyl group and X is a solubilising cation. Suitable cations include sodium, magnesium, potassium, ammonium, and mixtures thereof.

In general, the final composition should contain from 0.05 to 10% by weight of the magnesium salt of an anionic synthetic detergent, preferably from 0.1 to 7.5% by weight. The magnesium salt may be incorporated directly into the final composition, or may be formed in situ by neutralizing the anionic synthetic detergent in acid form with a suitable neutralizing magnesium substance, for example magnesium oxide, magnesium hydroxide, magnesium carbonate, etc. The magnesium salt of the anionic synthetic detergent may also be formed in situ by adding a magnesium salt, for example magnesium sulfate, to the alkali metal and ammonium synthetic detergent salt or to the alkanolamine salt in the composition.

In addition, or as an alternative to anionic surfactants, nonionic surfactants may be used. A preferred nonionic surfactant is selected from the group consisting of ethoxylated alcohols of the formula:

R ₁ - (OCH ₂ CH ₂ ) _m -OH where the straight or branched C 8 -C 18 alkyl is and the mean degree of ethoxylation (ie, the length of the ethylene oxide chain) m is 1 to 14.

As illustrated by reference to the examples below, it has been determined that particularly effective compositions are formed when the surfactant system consists solely of the magnesium salt of the anionic surfactant, in particular the magnesium salt of the primary alcohol sulfate.

Thus, preferred compositions of the invention include:

a) a magnesium salt of an anionic surfactant, preferably a magnesium salt of a primary alcohol sulfate.

b) 6% to 12% by weight of n-butoxypropanol

(c) water; and

(d) sufficiently volatile alcohol to prevent phase separation between water and n-butoxypropanol.

Minority ingredients

The compositions of the invention may further comprise other ingredients selected from the group consisting of surfactants, perfumes, electrolytes, dyes, abrasives, hygiene reagents, hydrotropes, and mixtures thereof. Provided that these components are present at sufficiently low levels, they do not interfere with the function of the invention.

Process aspects of the invention

It is preferred to spray the compositions directly onto the contaminated surface rather than cleaning the surface with a cloth or sponge soaked in the composition. It is believed that evaporation of one component of the cleaning composition is critical to the practice of the inventive compositions and that evaporation proceeds more effectively during the spraying operation and from the surface than from the rag.

Accordingly, another aspect of the invention includes a method comprising the steps of:

a) direct treatment of the surface with the composition of the invention

(b) leaving the second solvent component at least partially evaporated; and

c) performing a mechanical cleaning operation.

Yet another aspect of the invention relates to a homogeneous mixture comprising a solvent and a surfactant that decomposes into a water-solvent emulsion when part of the solvent evaporates, packaged in a spray-ready container.

In order that the present invention may be better understood, it will be described by way of example and with reference to the accompanying figures 1 and 2;

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a graph showing the concentration-dependent cleaning performance of commercial n-butoxypropan-2-ol, and Figure 2 illustrates the cleaning performance of compositions prepared as examples in graphical form.

DETAILED DESCRIPTION OF THE INVENTION

Examples 1 to 4

The cleaning compositions were prepared as shown in Table 1 below, all figures given in% by weight of the product and made up to 100% by weight with water. The following abbreviations are used to identify the components listed in Tables 1, 2 and 3:

PnB: Dowanol PnB [RTM]: n-butoxypropan-2-ol.

P2L: Pentan-2-ol.

IMS: Industrial methylated spirit, ethanol.

BD: Butyl Digol [RTM]: diethylene glycol butyl ether.

DOB: Dobanol 91-8 [RTM]: nonionic surfactant. NH3: Ammonia.

LAS: Linear alkylsulfonate: surfactant (as ammonium salt).

PAS: Magnesium Sulfate of C 1 -C 10 C primary alcohol: anionic surfactant.

NON: Dobanol 91-350FA [RTM]: nonionic surfactant

It can be seen from Figure 1 that the cleaning performance of the PnB-based compositions appears to be dependent on a PnB concentration ranging between 5 and 7% by weight of the concentration in the product. To obtain these results, 1.0 ml of each undiluted sample was applied with a sponge to contaminated Decamel 9 [RTM] tiles (contaminated with 0.25 mg / cm with 80/20 fat / particle mixture) wiped using 10 upstream Sheen friction cycles (so o

load 76 g / cm). Percent purification efficiency was calculated from reflectance measurements.

The maximum miscibility of PnB with water is about 6% by weight, and consequently preparations containing> 6% by weight are normally separated into an aqueous and excess solvent phase. It is clear from Figure 1 that the free solvent is much more effective than the solvent that is dissolved in an aqueous medium.

Single-phase mixtures were formed by simply mixing the ingredients according to the regulations given in Table 1, the balance in the formulation being water.

To determine the efficacy of the mixtures, 0.6 ml of each undiluted sample was sprayed onto contaminated Decamel [RTM] tiles (contaminated with 0.25 mg / cm with 80/20 fat / particle mixture) and left one minute before wiping with a sponge cloth using 10 upstream Sheen friction cycles (76 g / cm load). The percentage of cleaning efficiency was calculated from the reflectance measurements of the tile surface. Comparative examples are marked with an asterisk.

Table 1

Example DOB IMS BD PnB` * 1 0.09% 5% 2 * 0.09% 20% - 5% 3 0.09% 13% - 7% 4 * 0.09% 13% 7% -

The percent cleaning performance results for the above formulations are shown in Figure 2. In decreasing order, the cleaning efficiency was 3> 2> 1> 4.

Example 1 is a control experiment to illustrate the basic purification effect of a single phase PnB-containing system. The PnB level in this example was chosen to lie below the maximum miscibility with water and subsequently to form a homogeneous mixture. It can be seen from Comparative Example 2 that the addition of IMS increases the cleaning efficiency only slightly.

A significant increase is achieved when the initial PnB concentration is above the maximum miscibility level, as in Example 3. The mixtures of Example 3 are pure, homogeneous systems that, in use, lose the alcoholic solvent to the environment and achieve a composition in which only enough alcohol is present. solubilizing all PnB present. In this mixture, further loss of volatile solvent results in PnB phase separation.

Comparative Example 4 shows that when BD is present below its maximum miscibility in the initial mixture, purification is less efficient.

Examples 5 to 13

In order to further demonstrate the features of the present invention, numerous known compositions have been prepared as described in EP 0428816 with the composition shown in Table 2 below, and attention has been paid to their evaporative phase behavior. The balance in each mixture was water and the numbers quoted are percentages by weight in the product. Examples 5 to 12 marked with an asterisk are comparative examples, while Example 13 is an embodiment of the invention identical to Example 3 above.

Table 2

Example LA S NH3 IMS PnB` P2L DOB 5 0.1 9.0 0.5 0.5 6 0.1 - 9.0 0.5 1.0 - 7 0.1 - 9.0 0.5 1.5 - 8 0.1 - 9.0 0.5 2.0 - 9 0.1 - 9.0 0.5 2.5 - 10 0.1 - 9.0 0.5 3.0 - 11 0.1 0.2 9.0 1.5 1.5 12 0.1 - 8.0 3.0 3.0 - 13 - - 13 7.0 - 0.09

All samples were pure isotropic liquids at room temperature, not stroking sample 8, which was cloudy. This sample was therefore excluded from the following experiment.

In separate experiments, each sample was applied to black ceramic tiles and applied to a clean dry cloth surface to form a thin film that was allowed to evaporate to dryness. The film was observed up close by eyes to detect emulsion formation (indicated by conversion from transparent film to opaque film). The only sample in which emulsion formation was observed was sample 13, i. Embodiments of the invention.

Examples 14 to 27

Further examples are given in Table 3 below. Examples 14 to 27 illustrate the effect of surfactant selection on product production.

To obtain the results shown in Table 3, 1.0 ml of each undiluted sample was applied with a sponge for zney-cleaned Decamel [RTM] tiles (contaminated with 0.25 mg / cm with 80/20 fat / particle mixture) wiped manually using counter-friction cycles. The cleaning efficiency was determined in relation to the effort required: 1 corresponds to a small effort while 5 corresponds to some difficulty in removing the contamination. Comparative examples are marked with an asterisk.

As noted above, the maximum miscibility of PnB with water is about 6% by weight, and consequently formulations containing> 6% by weight are normally separated into an aqueous and excess solvent phase. However, in the presence of a co-solvent, the formulations of Examples 16-19 exhibit a single phase.

Table 3

Weight. % of the component PAS NON PnB` IPA IMS BD score samples * 14 - 0.1 5.0 - - - 4.7 * 15 0.1 - 5.0 - - - 5 16 0.1 7 13 - 2.3 17 0.1 - 7 13 - - 1.3 18 0.1 7 __ 13 2.3 19 0.1 - 7 - 13 - 2.3 * 20 0.1 20 5 * 21 - 0.1 - 20 - - 5 * 22 0.1 20 5 * 23 - 0.1 - - 20 - 5 * 24 0.1 10 5 * 25 0.1 - - - - 5 5 * 26 0.1 - - 5 - 5 5 * 27 0.1 - - - 5 5 5

Examples 14 and 16 are control experiments to illustrate the purification effect of a single phase PnB-containing system below the maximum miscibility. The cleaning performance of these compositions appears to be slightly better in the presence of a nonionic surfactant (Comparative Example 14) than in the presence of an anionic surfactant (Comparative Example 15). This is consistent with the results of the corresponding Comparative Example 1 above.

It can be seen from embodiments 17 and 19 that the addition of IPA or IMS as a co-solvent in the presence of a slightly elevated level of PnB greatly increases the cleaning performance. This is in line with the results discussed in Comparative Examples 1 and 3 above, as described above.

Examples 16 and 18 are examples of the use of a nonionic surfactant. Although these compositions had a cleaning performance attaining that of embodiments 17 and 19, the compositions became cloudy when stored. It should be noted that the anionic surfactant in the composition of the preferred embodiment of the present invention exhibits a better cleaning performance than the nonionic surfactant (cf. Examples 16 and 17).

Comparative Examples 20 to 27 show that solvent combinations falling outside the scope of the present invention did not have effective cleaning performance. In these comparative mixtures, no emulsion was formed when the volatile solvent component was evaporated.

From the examples above, it can be seen that homogeneous solvent systems that separate the emulsion-forming phases upon evaporation of a portion of the solvent provide increased cleaning performance over homogeneous systems that contain similar amounts of solvent but which do not exhibit phase separation behavior in use.

Claims (14)

A homogeneous, isotropic cleaning composition, containing a solvent, wherein the solvent system comprises: (a) the first solvent component in such an amount that it is present at a level above the water miscibility limit of that solvent component; and (b) a second solvent component in an amount such that the first solvent component is solubilized in the mixture, characterized in that the first solvent component is selected from glycol ethers and the second solvent component is sufficiently volatile to evaporate from the mixture leaving the emulsion in use solvent-water, which comprises a first solvent component and water. The composition of claim 1, wherein the first solvent component is selected from the group consisting of propylene glycol mono-n-butyl ether, dipropylene glycol mono-n-butyl ether, propylene glycol mono-t-butyl ether, di propylene glycol mono-tert-butyl ether. butyl ether, diethylene glycol hexyl ether and mixtures thereof. The composition of claim 1, wherein the second solvent component is selected from volatile alcohols; miscible with water volatile glycol ethers, aldehydes, ketones, dialkyl ethers and mixtures thereof. 4. The composition of claim 3 wherein the second solvent component is selected from the group consisting of: methanol, ethanol, isopropanol, ethylene glycol monobutyl ether, and mixtures thereof. The composition of claim 1, further comprising a surfactant. 6. A composition according to claim 5 comprising an anionic surfactant. The composition of claim 6, wherein the anionic surfactant is a primary alkyl sulfate salt of the formula: (ROSO ₃ ) X wherein R is a C 8 to C ₁₈ primary alkyl group and X is a suitable counterion. The composition of claim 7, further comprising magnesium ions in an amount corresponding to at least 0.02 M, wherein M is the molar amount of anionic surfactant in the composition. 9. The composition of claim 5 comprising a nonionic surfactant. 10. The composition of claim 5 comprising a nonionic surfactant selected from the group consisting of ethoxylated alcohols of the formula: R ₁ - (OCH ₂ CH ₂ ) _m -OH wherein straight or branched C 8 -C 18 alkyl and the mean degree of ethoxylation (ie the length of the ethylene oxide chain) m is 1 to 14. 11. A cleaning composition as claimed in claim 1 comprising: (a) 6% to 12% by weight of n-butoxypropanol; (b) water; (c) a sufficiently volatile alcohol to prevent phase separation between water and n-butoxypropanol. 12. The composition of claim 11, further comprising: (a) the magnesium salt of the anionic surfactant. 13. A method of purification comprising the steps of: a) direct treatment of the surface with the composition of the invention (b) at least partial evaporation of the second solvent component; and c) performing a mechanical cleaning operation. A composition according to any one of claims 1 to 12, characterized in that it is packaged in a container adapted to form a spray of said composition.