A emulsion for sealants, coatings and/or mastics having reduced volatile organic compounds is disclosed. The emulsion includes a slurry of substantially fully hydrated colloidal clay and a cutback in preferred ratios such that the emulsion has characteristics adapted to cold application processes. A method of reducing volatile organic compounds in sealants, coatings and/or mastics is also disclosed.

This invention relates generally to the field of sealants, coatings and mastics, and, more particularly to the use of emulsions as sealants, coatings and mastics for cold applications.
The use of bitumens and/or blends thereof for sealant, coating and mastic applications is well known. Bitumens are mixtures of heavy hydrocarbons, essentially naphthenic and paraffinic, originating from the distillation of crude oils. These products are distillation residues and are classified by their physical properties, their chemical properties varying very widely as a function of the origins of the crude. Generally speaking, conventional crudes contain up to 30% bitumen, and heavy crudes up to 50%. As bitumen requirements of the majority of countries represent 2 to 4% of their crude oil consumption, this means that bitumen is available in very plentiful supply. Bitumens contain such a diversity of constituents that it is impossible to define their exact composition; nevertheless, it is possible to classify these constituents into major chemical families:
saturated compounds, essentially paraffinic;
aromatic compounds, in which 30% of the carbon atoms are included in aromatic cycles, with a sulphur content of around 2 to 3%;
asphaltenes, which are insoluble in hydrocarbons, are aromatic and rich in sulphur, nitrogen, and oxygen; they take the form of black brittle solids practically incapable of being melted.
For given bitumens, the percentage of these various families depends heavily on the extraction method used. Thus, products of this type are essentially classified by the following physical properties: penetrability (NFT 66-004), softening point (NFT 66-008), density (NFT 66-007), flashpoint (NFT 60-118), solubility (NFT 66-012) ductility (NFT 66-006), brittleness point. Commercially available bitumens, classified by penetrability index, are generally situated between 10 and 200.
Such bitumens and/or blends can be applied to surfaces using xe2x80x9chot applicationxe2x80x9d or xe2x80x9ccold applicationxe2x80x9d methods. In hot applications, the composition is heated, typically to temperatures well over 100xc2x0 F., in order to decrease viscosity of the composition to facilitate application to the intended surface. Such heating requires special equipment and experienced personnel. Obviously, it is desirable to avoid working with a hot material at a job site, which may be a roof top, roadway, or similar surface, thus there has been a trend toward cold application compositions.
Various technologies have been developed to provide for cold application. They involve placing the bitumen in a fluid media, or vehicle, allowing for application without requiring heating. After application, the bitumen solidifies or cures through the elimination, in most cases by evaporation, of the vehicle. The two most common vehicles are solvents and water.
When using a solvent as the vehicle, the bitumen must be soluble in the solvent. Most often, the solvent is a petroleum distillate. Petroleum distillates produce blends that are commonly referred to as cutbacks or road oils. They vary in viscosity and cure rate depending on the type of base bitumen, type of solvent, and composition.
In such cutbacks, bitumens of differing physical characteristics may be blended to offer improved performance characteristics, e.g., elongation, recovery, and weatherability. Organic and inorganic fillers may be utilized to provide reinforcement and resistance to flow. The introduction of elastomers may be accomplished via solvation in aromatic and aliphatic hydrocarbon solvents, or combinations thereof. In such cases large amounts of various solvents are typically necessary to decrease the viscosity of the composition to facilitate spreading on the intended surface at ambient temperature. Typically, a standard composition of bitumen and solvent is modified by adding fillers, filbers, elastomers or other additives. When the desired amounts of such fillers, fibers, elastomer and/or other additives have been added to the composition it often must have more solvent added to allow for proper viscosity for pumping and/or application.
Such cutbacks have been used successfully in products for use as sealants, roof coatings and roof patches, mastics including plastic cements and the like. However, while these solvent-based compositions have great long term durability including a high degree of water resistance, the required use of large volumes of solvents results in the release of high levels of volatile organic compounds (xe2x80x9cVOCsxe2x80x9d) when the solvents evaporate as the compositions dries.
Many VOCs are known to be highly toxic and present health dangers. Others harm air quality, contribute to the creation of smog and are suspected to escalate global warming. Due to increasing concern over the effects of VOCs on humans and the environment, the need for compositions having lower levels of VOCs has become a high priority in the fields of sealants, coatings and mastics.
The use of water as the fluid media requires the action of surface active agents (emulsifiers). The mixture of water and bitumen produces a dispersion commonly called an emulsion. Bitumen emulsions consist of two types, those in which the bitumen is dispersed in an external or continuous phase of water, and those in which the water is dispersed in the external phase of bitumen.
The use of emulsions as compared to bitumen cutbacks is becoming increasingly popular as the product of choice for the non-heated applications. This is because of the dangers and hazards of solvent-containing compositions to the environment and hazards with employee exposure to solvents in manufacturing and application as discussed above. Storage stability, freeze thaw stability, limited compatibility with auxiliary additives, and low binder (bitumen solids) contents are deficiencies in current bitumen emulsions which hinder and often restrict their use.
For many years various clays have been used in combination with both petroleum- and coal tar-derived bitumens to form aqueous emulsions. These so-called xe2x80x9ccolloidal claysxe2x80x9d have many of the chemical and physical properties necessary to create and provide the emulsion the consistency and stability desired. However, colloidal clay emulsions have a tendency to phase-separate: the bitumen and clay particles (when in the discontinuous phase) settle over time, becoming a dense mass. Reblending into a homogeneous colloidal emulsion is often difficult and time-consuming. Phase-separation is especially troublesome and costly when extensive reblending is required just prior to application. The consequences of applying a phase-separated emulsion are even more undesirable and include: inadequate coverage rates, disabled spray equipment, non-uniform curing rates, varying cured-coating performance properties, and discolored and unsightly coating appearances, to mention but a few.
In order to reduce phase separation, manufacturers have attempted to achieve sufficient dispersion by extensive mixing of the water and colloidal clay slurry, typically for over 8 hours and often for much longer. However, such extensive mixing has still not led to a sufficiently stable bitumen emulsion mainly because full hydrolysis has not been obtained.
Concern over phase separation and the problems associated with it fostered the use of water-soluble gums, including cellulose ethers, which retard phase separation by absorbing water from the aqueous phase and increasing emulsion viscosity. While this approach is relatively inexpensive and alleviates many of the aforementioned concerns, it has associated with it a number of significant problems and deficiencies. Most are related to inadequate emulsion performance and phase-separation.
Another significant problem with the use of water-soluble gums is the required addition of biocides. Cellulose thickeners are, for the most part, vegetable matter. For example, cellulose gums are derived from various sources, including wood pulp and cotton. These materials support fungal and bacterial life, the bi-products of which are weakly acidic and may later xe2x80x9csourxe2x80x9d the emulsion causing phase separation. As a preventative measure, synthetic biocides must be added during emulsion formulation and represent an extra production cost.
In summary, a considerable number of drawbacks and problems exist in the art relating to bituminous emulsions and bituminous cutbacks. There is a need for an improved bitumen composition for safe application with reduced VOCs. The applicants have consequently set out to obtain bitumen cutback emulsions which retain stability, avoid flocculation, and achieve the desired characteristics for application while avoiding complex or expensive formulations.
A primary object of the present invention to provide bitumen cutback emulsions for use as sealants, coatings and/or mastics which may be easily and efficiently manufactured and applied.
Another object of the invention is to proved a cold application emulsion which is of durable and reliable construction.
Another object of the invention is to provide a low cost method of manufacturing a cold application bitumen cutback emulsion.
Another object of the invention is to reduce settling and storage separation in cold application emulsions of sealants, coatings and/or mastics.
Yet another object of the invention is to allow for precise viscosity control in a cold application emulsion.
Another object of the invention is to provide an emulsion for cold application of sealants, coatings and/or mastics which has substantially reduced levels of VOCs.
Another object of the invention is to provide a composition for cold application of sealants, coatings and/or mastics which provides for increased spreadability, greater control of spread rates, and more uniform film thickness.
Another object of the invention is to provide a composition which has a reduced flammability hazard.
Still another object of the invention is to provide a composition for cold application of sealants, coatings and/or mastics which has reduced film stresses and tensions when dried.
Another object of the invention is to provide an emulsion for cold application of sealants, coatings and/or mastics which results in increased abrasion and track resistance.
Another object of the invention is to provide a method of producing an effective composition for the cold application of sealants, coatings and/or mastics which has reduced VOC levels through the use of bentonite.
Still another object of the invention is to provide a stable emulsion of a slurry of substantially fully hydrated colloidal clay and water in a bitumen cutback.
Still another object of the invention is to provide a method of quickly producing a slurry of substantially fully hydrated colloidal clay and water for emulsion in a bitumen cutback.
These and other objects of the invention will be apparent from the disclosure and discussion herein.
This invention is an emulsion of a colloidal clay and water slurry in a cutback. The invention represents a significant advance over the state of the art by providing novel elements to provide increased stability and performance characteristics.
In accordance with the invention, an improved emulsion adapted for cold application of sealants, coatings and/or mastics is provided. The emulsion includes a reduced number of VOCs compared to typical cold application emulsions. More specifically, the emulsion provides for adequate use in cold applications through the use of colloidal clay, preferably treated bentonite, which preferably comprises between about 0.5-25 weight % of the emulsion (xe2x80x9cwt. %xe2x80x9d). The emulsion comprises a cutback in addition to the clay and water slurry, preferably a bitumen cutback.
A preferred embodiment of the emulsion includes between about 0.5-25 wt. % bentonite, between about 20-95 wt. % bitumen cutback, and between about 3-55 wt. % water. In certain embodiments, the emulsion may further include an additive comprising between about 0.2-1 wt. % of the emulsion, a non-asbestos fiber comprising between about 0-10 wt. % of the emulsion, a filler comprising between about 3-15 wt. % of the emulsion, and an elastomer comprising between about 0-8 wt. % of the emulsion since the slurry provides for excellent mixing with such additional components.
The inventive method of preparing a low-VOC cold-application emulsion for coatings comprises providing a cutback; providing a slurry of water and colloidal clay; adding fibers and/or fillers to the cutback; mixing the slurry with the cutback such that the resulting emulsion has desired characteristics such as an appropriate viscosity for pumping and/or application, color, spreadability, controlled spread rates, uniform film thickness and track resistance. The preferred method may further comprise creating the slurry by mixing the water and colloidal clay in a high-speed disperser which preferably operates between about 1500-5000 rpms, and most preferably operates at about 3000 rpms. Such mixing preferably continues until the colloidal clay is substantially fully hydrated, i.e., the clay can absorb substantially no more water. In a preferred method, the clay is substantially fully hydrated in a short period of time such as less than 30 minutes, and more preferably in about 10 to 15 minutes.
As stated above, the preferred colloidal clay is bentonite, most preferably treated bentonite. Treated bentonite meets the American Petroleum Institute""s requirements of having a Viscometer Dial Reading of 30 or more at 600 rpm; a Yield Point/Plastic Viscosity Ratio of 3 or more; a Filtrate Volume of 15.0 cubic cm or less; a Residue greater than 75 micrometers of 4.0 wt. % or less; and a Moisture of 10.0 wt. % or less. Such treated bentonite must yield approximately 120 to 280 barrels of 15 centipoises mud per ton, and preferably about 180 to 240 barrels per ton. Standard testing procedures for such properties can be found at the API""s Specification 13A. The slurry preferably comprises about 1-15% bentonite by weight, more preferably the slurry comprises about 8-12% bentonite by weight.
The cutback preferably comprises about 50-90% bitumen and about 10-50% solvent. More preferably, the cutback comprises about 60-80% bitumen and about 20-40% solvent. Most preferably, the cutback comprises about 70% bitumen and about 30% solvent. In some embodiments, the cutback comprises a resin rather than a bitumen or a resin in addition to a bitumen. The preferred solvent is a mineral spirit/Stoddard solvent.
The emulsion is preferably of the water-in-oil type such that the phase of water is discontinuous and the cutback phase is continuous. Such an emulsion allows for the cutback to xe2x80x9cbitexe2x80x9d into surfaces upon application, i.e., the emulsion has good adhesiveness such that it can adhere to asphalt shingles, galvanized steel and other difficult surfaces. In the emulsion, the water is preferably substantially de-ionized, although various levels of ions in the water may be desired in order to provide a specific formulation. The emulsion is preferably 0.5-11% colloidal clay and 20-95% cutback by weight. In more preferred embodiments, the emulsion is less than 15% solvent by weight.
Such a reduction is significant over typical prior art compositions. For instance, in the past 500 liters of 70/30 cutback may have 300 liters of fiber and/or filler added to provide desired application or endurance characteristics. In order to prepare such a composition for application, another 200 liters of solvent may be necessary to provide the appropriate viscosity. The applicants"" invention provides for the same application that 450 liters of 70/30 cutback may be mixed with 450 liters of the preferred slurry and 100 liters of fiber and/or filler. Such an emulsion uses a less than 40% as much solvent as in the prior art (135 liters vs. 350 liters).
The invention is also described as an emulsion for use as a low-VOC cold-application coating formed by a cutback and a slurry of bentonite and water. In such an emulsion, the bentonite is preferably substantially fully hydrated. The bentonite preferably meets the requirements of API specification 13A as discussed above. The emulsion may further comprise additives, non-asbestos fiber, fillers and/or an elastomer. Such components can be used to control specific characteristics of the emulsion such as color, spreadability, flexibility, etc.
As a low-VOC emulsion, the emulsion is comprised of preferably less than about 30% solvent by weight, more preferably less than about 20% solvent by weight and most preferably less than about 15% solvent by weight. In certain embodiments the emulsion comprises about 45% cutback, 45% slurry and 10% fiber and/or filler.
In certain preferred embodiments, the bitumen is asphalt or coal tar and is preferably a high melt bitumen, i.e., it has a melting point of at least about 160xc2x0 F. In certain other preferred embodiments, the bitumen has a melting point of at least about 180xc2x0 F. or of at least about 200xc2x0 F.
Bentonite is a colloidal clay mineral found throughout the world in deposits of volcanic origin. Chemically, bentonite clay is in the smectite group of colloidal clays which also includes hectorite, saponite and beidellite. Each of these materials exists as three layers which are typically 0.2 to 2.0 microns in diameter and 6 to 10 Angstroms in thickness. The layers may be separated by interlayer galleries containing cations and water. When exposed to water, the clay surface and interlayer cations hydrate and the interlayer spacing increases in a series of steps and may eventually exfolitiate to form a suspension of individual platelets.
Bitumens such as asphalt and coal tar are manufactured by a variety of methods producing types and grades of different specifications. The properties range from soft and flowable to hard and brittle. Bitumen has uses in coating, sealing, and adhesive applications in construction and industrial applications. It is thermoplastic in nature, that is, it needs to be heated above their melting point in order to be applied without a liquid vehicle.
Asphalt is a bitumen derived from a number of materials such as, for example, petroleum, gilsonite, shale oil, coal tar and the like. It is typically a viscous black mixture of compounds of parafinnic, cycloaliphatic and aromatic compounds. It may also contain sulfur, nitrogen and oxygen. While asphalt can be obtained from natural sources it is primarily derived as the residue of petroleum distillation (e.g. the bottom product of a vacuum distillation of a topped crude). Although not limited, preferred grades have a penetration value of (ASTM D5) of no more than 300 dmm, preferably 50 to 200 dmm, and conform in general to ASTM D312, D946 or D449.
Coal tar is a bitumen derived from crude coal tar, water gas tar, oil gas tar or from a combination of such tars with their constituents. Coal tar is black, viscous, with naphthalene-like odor, amorphous residue resulting mainly from the distillation of coal. The majority of its composition is polynuclear aromatic compounds such as aromatic hydrocarbon, naphthalenic, phenolic, anthracenic, quinolinic compounds with traces of insoluble materials. Different grades have different float tests and softening points. Although this invention is not constrained to such limitations, the preferred coal tars have a float test at 122xc2x0 F. ranging from about 75-230 seconds, and more preferably from about 180-220 seconds, and conform in general to the specification outlined by RT-10 (Road tar-10), RT-11 and RT-12 in ASTM D490. The coal tar can be utilized in the form of an aqueous emulsion readily available in the trade (see Federal Specification RP355e) and thus has a maximum water content of about 53 wt. %.
Bitumen cutback is a mixture of bitumen and hydrocarbon solvent. Hydrocarbon solvents include kerosene, fuel oils, jet fuel, mineral spirit/Stoddard, naphtha, high flash aromatic, low flash aromatic, xylene, toluene, and other petroleum solvent products. For certain embodiments of this invention, the preferred cutback is a mixture of asphalt bitumen and mineral spirit/Stoddard solvent.
Surprisingly, it has been found that certain high efficiency, low sodium bentonites, when dispersed under high-speed mixers in the presence of certain additives can become substantially fully hydrated and form water-based slurries that may be blended with solvent-based asphalt cutback to form stable emulsions for use as cold application sealants, coatings and/or mastics. The bentonite slurry can be used as a replacement for much of the solvents used in typical compositions since it provides for a stable, suitable emulsion viscosity. Therefore, lower levels of VOCs are found in the inventive emulsion, thereby reducing the level of VOC emissions, flammability and the odor of VOCs both when wet and dry.
The use of bentonite improves the emulsion beyond achieving lower VOC levels. First, it provides the emulsion with thixotropic viscosity in which the emulsion becomes fluid when stirred or shaken and returns to the semisolid state upon standing. Such behavior greatly reduces settling and storage separation between the slurry and cutback which allows for little or no stirring before use since the components need not be mixed back together.
Second, the presence of bentonite in the emulsion facilitates ease of formulation since various fibers, fillers and resins, among other additives, can be compounded in the emulsion for precise and stable viscosity control. Furthermore, such emulsions are not subject to bacteria degradation. Such characteristics result in emulsions which are equal to or even superior to asbestos-containing products without having the drawbacks associated with asbestos.
In addition, such bentonite-including emulsions have superior application characteristics including longer open time, greater ease when spreading the emulsion, greater control of spread rates, more uniform film application thicknesses and applicability on damp surfaces.
The inventive emulsion also has reduced film stresses and tensions when dried, meaning that the compound is less prone to cracks and, ultimately, failure. The more durable surface translates into superior abrasion resistance, superior track resistance, resistance to softening when warmed and superior solvent resistance.
Lastly, the emulsion including bentonite is less costly to produce than current products.
A preferred process of producing water reducible bituminous sealants, coatings and/or mastics and in accordance with the invention is as follows:
1. Treated bentonite clay is added into clean water in a high-speed mixing agitator such that the mixture comprises about 4-12% bentonite (more preferably 8-12%). During mixing, the clay is dispersed or high sheared in a colloid mill until it turns into a clay slurry. The viscosity of the clay slurry is preferably between about 20,000-180,000 centiposes (CPS) at 77xc2x0 F.
2. Cutback consisting of between about 50-90% bitumen and between about 10-50% mineral spirit Stoddard solvent is provided and is mixed with a selected amount of the slurry to form a soluble system.
3. An additive is added to the cutback to enhance the stability of the soluble system.
4. Non-asbestos fiber is added to reinforce the soluble system sealant/coating/mastic film strength. It also provides additional viscosity and texture. Such fibers may include cellulosic paper, fiberglass, mineral fiber, or polymer fiber including polypropylene and polyethylene.
5. Non-reactive fibers commonly called pigment extenders, e.g., natural or calcined clay, mica and silica powder, slate powder, coal ash, fly ash, etc., are added to the system to improve film strength and consistency.
6. Elastomers, which may include SBR, SBS, SIBS, acrylic, styrene, neoprene, polyvinyl, etc., are added to impart buffering as well as tensile strength to the emulsion.
7. If necessary, another selected amount of slurry may be mixed with the system to further control the desired characteristics for application without adding additional solvents.

Emulsion of a colloidal clay and water slurry in a bitumen cutback


All purpose cleaning or microemulsion compositions more environmentally friendly, which is especially effective in the removal of oily or greasy soils, contains a charged surfactant-polymer complex, a hydrocarbon ingredient, a cosurfactant, and water.

The present invention relates to a hard surface cleaning composition containing a charged surfactant-polymer complex.
This invention relates to an improved all-purpose liquid cleaner designed in particular for cleaning hard surfaces and which is effective in removing grease soil and/or bath soil and in leaving unrinsed surfaces with a shiny appearance.
In recent years all-purpose liquid detergents have become widely accepted for cleaning hard surfaces, e.g., painted woodwork and panels, tiled walls, wash bowls, bathtubs, linoleum or tile floors, washable wall paper, etc.. Such all-purpose liquids comprise clear and opaque aqueous mixtures of water-soluble synthetic organic detergents and water-soluble detergent builder salts. In order to achieve comparable cleaning efficiency with granular or powdered all-purpose cleaning compositions, use of water-soluble inorganic phosphate builder salts was favored in the prior art all-purpose liquids. For example, such early phosphate-containing compositions are described in U.S. Pat. Nos. 2,560,839; 3,234,138; 3,350,319; and British Patent No. 1,223,739.
In view of the environmentalist""s efforts to reduce phosphate levels in ground water, improved all-purpose liquids containing reduced concentrations of inorganic phosphate builder salts or non-phosphate builder salts have appeared. A particularly useful self-opacified liquid of the latter type is described in U.S. Pat. No. 4,244,840.
However, these prior art all-purpose liquid detergents containing detergent builder salts or other equivalent tend to leave films, spots or streaks on cleaned unrinsed surfaces, particularly shiny surfaces. Thus, such liquids require thorough rinsing of the cleaned surfaces which is a time-consuming chore for the user.
In order to overcome the foregoing disadvantage of the prior art all-purpose liquid, U.S. Pat. No. 4,017,409 teaches that a mixture of paraffin sulfonate and a reduced concentration of inorganic phosphate builder salt should be employed. However, such compositions are not completely acceptable from an environmental point of view based upon the phosphate content. On the other hand, another alternative to achieving phosphate-free all-purpose liquids has been to use a major proportion of a mixture of anionic and nonionic detergents with minor amounts of glycol ether solvent and organic amine as shown in U.S. Pat. No. 3,935,130. Again, this approach has not been completely satisfactory and the high levels of organic detergents necessary to achieve cleaning cause foaming which, in turn, leads to the need for thorough rinsing which has been found to be undesirable to today""s consumers.
Another approach to formulating hard surfaced or all-purpose liquid detergent composition where product homogeneity and clarity are important considerations involves the formation of oil-in-water (o/w) microemulsions which contain one or more surface-active detergent compounds, a water-immiscible solvent (typically a hydrocarbon solvent), water and a xe2x80x9ccosurfactantxe2x80x9d compound which provides product stability. By definition, an o/w microemulsion is a spontaneously forming colloidal dispersion of xe2x80x9coilxe2x80x9d phase particles having a particle size in the range of 25 to 800 xc3x85 in a continuous aqueous phase.
In view of the extremely fine particle size of the dispersed oil phase particles, microemulsions are transparent to light and are clear and usually highly stable against phase separation.
Patent disclosures relating to use of grease-removal solvents in o/w microemulsions include, for example, European Patent Applications EP 0137615 and EP 0137616xe2x80x94Herbots et al; European Patent Application EP 0160762xe2x80x94Johnston et al; and U.S. Pat. No. 4,561,991xe2x80x94Herbots et al. Each of these patent disclosures also teaches using at least 5% by weight of grease-removal solvent.
It also is known from British Patent Application GB 2144763A to Herbots et al, published Mar. 13, 1985, that magnesium salts enhance grease-removal performance of organic grease-removal solvents, such as the terpenes, in o/w microemulsion liquid detergent compositions. The compositions of this invention described by Herbots et al. require at least 5% of the mixture of grease-removal solvent and magnesium salt and preferably at least 5% of solvent (which may be a mixture of water-immiscible non-polar solvent with a sparingly soluble slightly polar solvent) and at least 0.1% magnesium salt.
However, since the amount of water immiscible and sparingly soluble components which can be present in an o/w microemulsion, with low total active ingredients without impairing the stability of the microemulsion is rather limited (for example, up to 18% by weight of the aqueous phase), the presence of such high quantities of grease-removal solvent tend to reduce the total amount of greasy or oily soils which can be taken up by and into the microemulsion without causing phase separation.
The following representative prior art patents also relate to liquid detergent cleaning compositions in the form of o/w microemulsions: U.S. Pat. Nos. 4,472,291xe2x80x94Rosario; 4,540,448xe2x80x94Gauteer et al; 3,723,330xe2x80x94Sheflin; etc.
Liquid detergent compositions which include terpenes, such as d-limonene, or other grease-removal solvent, although not disclosed to be in the form of o/w microemulsions, are the subject matter of the following representative patent documents: European Patent Application 0080749; British Patent Specification 1,603,047; 4,414,128; and 4,540,505. For example, U.S. Pat. No. 4,414,128 broadly discloses an aqueous liquid detergent composition characterized by, by weight:
(a) from 1% to 20% of a synthetic anionic, nonionic, amphoteric or zwitterionic surfactant or mixture thereof;
(b) from 0.5% to 10% of a mono- or sesquiterpene or mixture thereof, at a weight ratio of (a):(b) being in the range of 5:1 to 1:3; and
(c) from 0.5% 10% of a polar solvent having a solubility in water at 15xc2x0 C. in he range of from 0.2% to 10%. Other ingredients present in the formulations disclosed in this patent include from 0.05% to 2% by weight of an alkali metal, ammonium or alkanolammonium soap of a C13-C24 fatty acid; a calcium sequestrant from 0.5% to 13% by weight; non-aqueous solvent, e.g., alcohols and glycol ethers, up to 10% by weight; and hydrotropes, e.g., urea, ethanolamines, salts of lower alkylaryl sulfonates, up to 10% by weight. All of the formulations shown in the Examples of this patent include relatively large amounts of detergent builder salts which are detrimental to surface shine.
A pH neutral microemulsion composition based on paraffin sulfonate and ethoxylated nonionic surfactant is able to deliver improved grease cleaning versus built, alkaline compositions. Besides the improved grease cleaning, this approach is much safer to surfaces as well as less aggressive on consumer""s hands (Loth et alxe2x80x94U.S. Pat. No. 5,075,026).
The microemulsion technology provides outstanding oil uptake capacity because of the adjustment of the curvature of the surfactant micelles by the molecules of the cosurfactant. Rod-like micelles are preferred as they can xe2x80x9cswallowxe2x80x9d oil to become globular without increasing the surface of contact between the hydrophobic core of the micelle and the hydrophilic continuous phase.
In diluted usage however, the microemulsion state is usually lost and the cleaning performance relies on the adsorption efficacy and leaving character of the surfactant system. Nonionic surfactants perform very well on grease, as they are excellent grease xe2x80x9csolubilizersxe2x80x9d. Actually, they spontaneously form swollen micelles. In moderate climate countries such as the northern states of the United States and the northern countries of Europe, the soil on the hard surfaces contains a major proportion of greasy materials. It is accordingly not surprising that the anionic-nonionic surfactant based microemulsion is very efficient in those countries. However, nonionic surfactants do not impart oil repelling properties and can not deliver soil antiattachment properties on treated hard surfaces so as to achieve next time easier cleaning of said treated surface.
The instant invention teaches hard surface cleaning containing a charged complex of an anionic surfactant which is an alkali metal salt such as sodium of a fluoroalkyl sulfonate, or an ammonium salt of a fluoroalkyl sulfonate, or a mixture hereof, which exhibits very low surface tensions with either poly[4-vinyl pyridine N-oxide] or polyvinyl pyridine betaine which imparts oil repelling properties and delivers soil antiattachment properties on treated hard surfaces.
The present invention provides an improved, clear, liquid hard surface cleaning composition having improved interfacial tension which improves cleaning hard surfaces such as plastic, vitreous and metal surfaces having a shiny finish, oil stained floors, automative engines and other engines. More particularly, the improved cleaning compositions exhibit good grease soil removal properties and leave the cleaned surfaces shiny without the need of or requiring only minimal additional rinsing or wiping. The latter characteristic is evidenced by little or no visible residues on the unrinsed cleaned surfaces and, accordingly, overcomes one of the disadvantages of prior art products. The instant compositions exhibit a grease release effect in that the instant compositions impede or decrease the anchoring of greasy soil on surfaces that have been cleaned with the instant compositions as compared to surfaces cleaned with a microemulsion composition which means that the grease soiled surface is easier to clean upon subsequent cleanings.
Surprisingly, these desirable results are accomplished even in the absence of polyphosphate or other inorganic or organic detergent builder salts and also in the complete absence or substantially complete absence of grease-removal solvent.
In one aspect, the invention generally provides a stable, clear all-purpose, hard surface cleaning composition especially effective in the removal of oily and greasy oil. The cleaning composition includes, on a weight basis:
about 0.1% to about 20%, more preferably about 0.2% to about 15% of a charged complex comprising at least one alkali metal salt of a fluoroalkyl sulfonate surfactant, or at least one ammonium salt of a fluoroalkyl sulfonate surfactant, or mixtures thereof, and either poly[4-vinyl pyridine N-oxide] or polyvinylpyridine betaine;
about 0 to about 25%, more preferably 1% to 20%, of a water-mixable cosurfactant having either limited ability or substantially no ability to dissolve oily or greasy soil;
0 to about 1.5% of a fatty acid;
0 to about 5% of magnesium sulfate heptahydrate;
about 0 to about 5.0% of a perfume or water insoluble hydrocarbon; and
the balance being water, said proportions being based upon the total weight of. the composition.
The cleaning composition can be in the form of a microemulsion in which case the concentration of the water mixable cosurfactant is about 0 to about 25 wt. %, preferably about 1 wt. % to about 20 wt. % and the concentration of the perfume or water insoluble hydrocarbon is about 0.4 wt. % to about 5.0 wt. %. The dispersed oil phase of the o/w microemulsion is composed essentially of a water-immiscible or hardly water-soluble perfume.
The present invention relates to a stable all purpose hard surface cleaning or microemulsion composition containing a surfactant-polymer complex for delivering soil antiattachment properties. The invention also relates to a light duty liquid composition or light duty liquid microemulsion composition. This present invention also useful in the formation of toilet bowl cleaners.
The present invention relates to a stable hard surface cleaning composition approximately by weight: 0.1% to 20% of a charged complex of an alkali metal salt of a fluoroalkyl sulfonate surfactant, or an ammonium salt of a fluoroalkyl sulfonate surfactant, or mixtures thereof, and a vinyl pyridine compound selected from the group consisting of poly[4-vinyl pyridine N-oxide] (PVNO) having an average molecular weight of 20,000 to 50,000 and polyvinyl pyridine betaine (PVB) having a molecular weight of 10,000 to 250,000 and mixtures thereof, 0 to 25% of a cosurfactant, 0 to 5% of a water insoluble hydrocarbon or a perfume and the balance being water, wherein the cleaning composition can be in the form of a microemulsion in which case the concentration of the water mixable cosurfactant is about 0 to about 25.0 wt. %, preferably about 0.1 wt. % to about 25.0 wt. % and the concentration of the perfume or water insoluble hydrocarbon is about 0.4 wt. % to about 5.0 wt. %.
When mixing an alkali metal salt such as the sodium salt of a fluorinated anionic surfactant, or an ammonium salt of a fluorinated anionic surfactant, or a mixture thereof, and a polymer bearing positively charged sites or highly dipolar groups along its backbone, attractive interactions are developed that are very strong and lead to the formation of anionic-cationic complexes in-situ. The complex interactions take place along the polymer backbone, so that surfactant-polymer complexes exist in solution. Attention must be paid not to complex all the positively charged sites or all the highly dipolar groups on the polycationic polymer so as to still have enough electric charges or highly dipolar groups on the whole structure so as to keep the complex water soluble (otherwise phase separation or precipitation might occur). The presence of positive charges on the surfactant-polymer system allows subsequent anchorage on substrate surface for modifying the surface energy.
One of the objects of the instant invention is to deliver higher proportions of a fluoroalkyl anionic surfactant in the adsorbed layer at the solid-water interface by means of surfactant-polymer mixtures. This is due to a boosted adsorption tendency, as compared to fluoroalkyl anionic individual surfactant, by means of neutralization between the negative charge of the anionic surfactant and the positive charge of the polymer, or by means of strongly attractive interactions between the negative charge of the anionic surfactant and the positive side of dipolar groups of the polymer that is used in admixture with the anionic surfactant in the instant compositions, and due to an increased hydrophobic character imparted to the polymer by the anionic surfactant linked to its backbone. Two anionic surfactants can be used in composition wherein one of the anionic surfactants will possibly preferentially associate with the polymer through electrostatic interactions.
According to the present invention, the role of the hydrocarbon is provided by a non-water-soluble perfume. Typically, in aqueous based compositions the presence of a solubilizers, such as alkali metal lower alkyl aryl sulfonate hydrotrope, triethanolamine, urea, etc., is required for perfume dissolution, especially at perfume levels of 1% and higher, since perfumes are generally a mixture of fragrant essential oils and aromatic compounds which are generally not water-soluble. Therefore, by incorporating the perfume into the aqueous cleaning composition as the oil (hydrocarbon) phase of the ultimate o/w microemulsion composition, several different important advantages are achieved.
First, the cosmetic properties of the ultimate cleaning composition are improved: the compositions are both clear (as a consequence of the formation of a microemulsion) and highly fragranced (as a consequence of the perfume level).
Second, the need for use of solubilizers, which do not contribute to cleaning performance, is eliminated.
Third, an improved grease release effect and an improved grease removal capacity in neat (undiluted) usage of the composition or after dilution of the composition can be obtained without detergent builders or buffers or conventional grease removal solvents at neutral or acidic pH and at low levels of active ingredients while improved cleaning performance can also be achieved in diluted usage.
As used herein and in the appended claims the term xe2x80x9cperfumexe2x80x9d is used in its ordinary sense to refer to and include any non-water soluble fragrant substance or mixture of substances including natural (i.e., obtained by extraction of flower, herb, blossom or plant), artificial (i.e., mixture of natural oils or oil constituents) and synthetically produced substance) odoriferous substances. Typically, perfumes are complex mixtures of blends of various organic compounds such as alcohols, aldehydes, ethers, aromatic compounds and varying amounts of essential oils (e.g., terpenes) such as from 0% to 80%, usually from 10% to 70% by weight. The essential oils themselves are volatile odoriferous compounds and also serve to dissolve the other components of the perfume.
In the present invention the precise composition of the perfume is of no particular consequence to cleaning performance so long as it meets the criteria of water immiscibility and having a pleasing odor. Naturally, of course, especially for cleaning compositions intended for use in the home, the perfume, as well as all other ingredients, should be cosmetically acceptable, i.e., non-toxic, hypoallergenic, etc.
The hydrocarbon such as a perfume is present in the hard surface cleaning composition in an amount of from 0 to 5% by weight, preferably 0.4% to 5% by weight, more preferably from 0.4% to 3.0% by weight, especially preferably from 0.5% to 2.0% by weight. If the hydrocarbon (perfume) is added in amounts more than 5% by weight, the cost is increased without any additional cleaning benefit and, in fact, with some diminishing of cleaning performance insofar as the total amount of greasy or oily soil which can be taken up in the oil phase of the microemulsion will decrease proportionately.
Furthermore, although superior grease removal performance will be achieved for perfume compositions not containing any terpene solvents, it is apparently difficult for perfumers to formulate sufficiently inexpensive perfume compositions for products of this type (i.e., very cost sensitive consumer-type products) which includes less than 20%, usually less than 30%, of such terpene solvents.
Thus, merely as a practical matter, based on economic consideration, the microemulsion compositions of the present invention may often include as much as 0.2% to 7% by weight, based on the total composition, of terpene solvents introduced thereunto via the perfume component. However, even when the amount of terpene solvent in the cleaning formulation is less than 1.5% by weight, such as up to 0.6% by weight or 0.4% by weight or less, satisfactory grease removal and oil removal capacity is provided by the inventive diluted microemulsions.
In place of the perfume one can employ a water insoluble paraffin or isoparaffin having 6 to 18 carbon at a concentration of 0 to 5 wt. percent, preferably 0.4 to 5.0 wt. percent, more preferably 0.4 to 3.0 wt. %.
The charged complex contained in the instant compositions comprises a complex of:
(a) an alkali metal salt such as sodium of a fluoroalkyl sulfonate anionic surfactant, or an ammonium salt of a fluoroalkyl sulfonate anionic surfactant, or mixtures thereof; and
(b) a polymer which is selected from the group consisting of poly[4-vinyl pyridine N-oxide] (PVNO) and polyvinyl pyridine betaine (PVB) and mixtures thereof, wherein the molar ratio of the anionic surfactant to the highly dipolar or positively charged binding sites available on the polymer backbone is 0.95:1 to 0.05:1, more preferably 0.9:1 to 0.1:1. The instant composition contains about 0.1 to about 20 wt. %, more preferably about 0.2 to about 15 wt. % of the charged complex.
The fluoroalkyl sulfonate anionic surfactant which has a RF fluoroalkyl group which is a C16F33 to C5F11, preferably a C6F13 to C10F21 fluoroalkyl group and can be selected among the different compounds being depicted by the following structures of, perfluoroalkane sulfonate salt:
RFxe2x80x94SO3xe2x88x92X+
perfluoroalkylethane sulfonate salt:
perfluoroalkyl group containing sulfonate with sulfide and carbonamide linkages:
wherein, X can be an alkali metal counterion such as sodium, or an ammonium counterion such as NH4+, and R1 and R2 are H or methyl groups.
A cosurfactant can be optionally used in forming the microemulsion composition. Three major classes of compounds have been found to provide highly suitable cosurfactants over temperature ranges extending from 5xc2x0 C. to 43xc2x0 C. for instance; (1) water-soluble C3-C4 alkanols, polyethylene glycols of the formula HO(CH2CH2O)nH wherein n is about 8 to about 14, polypropylene glycol of the formula HO(CH3CHCH2O)nH wherein n is a number from 2 to 18 and copolymers of ethylene oxide and propylene oxide and mono C12-C6 alkyl ethers and esters of ethylene glycol and propylene glycol having the structural formulas R(X)nOH and R1(X)nOH wherein R is C1-C6 alkyl, R1 is C2-C4 acyl group, X is (OCH2CH2) or (OCH2(CH3)CH) and n is a number from 1 to 4; (2) aliphatic mono- and di-carboxylic acids containing 2 to 10 carbon atoms, preferably 3 to 6 carbons in the molecule; and (3) triethyl phosphate. Additionally, mixtures of two or more of the three classes of cosurfactant compounds may be employed where specific pH""s are desired.
When the mono- and di-carboxylic acid (Class 2) cosurfactants are employed in the instant microemulsion compositions at a concentration of 0.5 to 10 wt. %, the microemulsion compositions can be used as a cleaners for bathtubs and other hard surfaced items, which are acid resistant thereby removing lime scale, soap scum and greasy soil from the surfaces of such items damaging such surfaces. If these surfaces are of zirconium white enamel, they can be damaged by these compositions.
An aminoalkylene phophoric acid at a concentration of 0.01 to 0.2 wt. % can be optionally used in conjunction with the mono- and di-carboxylic acids, wherein the aminoalkylene phosphoric acid helps prevent damage to zirconium white enamel surfaces. Additionally, 0.05 to 1% of phosphoric acid can be used in the composition.
Representative members of the polypropylene glycol include dipropylene glycol and polypropylene glycol having a molecular weight of 200 to 1000, e.g., polypropylene glycol 400. Other satisfactory glycol ethers are ethylene glycol monobutyl ether (butyl cellosolve), diethylene glycol monobutyl ether (butyl carbitol), propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, triethylene glycol monobutyl ether, mono, di, tri propylene glycol monobutyl ether, tetraethylene glycol monobutyl ether, triethylene glycol monohexyl ether, tetraethylene glycol monohexyl ether, pentaethylene glycol monohexyl ether, propylene glycol tertiary butyl ether, ethylene glycol monoacetate and dipropylene glycol propionate.
Representative members of the aliphatic carboxylic acids include C3-C6 alkyl and alkenyl monobasic acids such as acrylic acid and propionic acid and dibasic acids such as glutaric acid and mixtures of glutaric acid with adipic acid and succinic acid, as well as mixtures of the foregoing acids.
While all of the aforementioned glycol ether compounds and acid compounds provide the described stability, the most preferred cosurfactant compounds of each type, on the basis of cost and cosmetic appearance (particularly odor), are diethylene glycol monobutyl ether, or pentaethylene glycol monohexyl ether, and a mixture of adipic, glutaric and succinic acids, respectively. The ratio of acids in the foregoing mixture is not particularly critical and can be modified to provide the desired odor. Generally, to maximize water solubility of the acid mixture glutaric acid, the most water-soluble of these three saturated aliphatic dibasic acids, will be used as the major component.
Generally, weight ratios of adipic acid: glutaric acid:succinic acid is 1-3:1-8:1-5, preferably 1-2:1-6:1-3, such as 1:1:1, 1:2:1, 2:2:1, 1:2:1.5, 1:2:2, 2:3:2, etc. can be used with equally good results.
Still other classes of cosurfactant compounds providing stable microemulsion compositions at low and elevated temperatures are the mono-, di- and triethyl esters of phosphoric acid such as triethyl phosphate.
The amount of cosurfactant which might be required to stabilize the microemulsion compositions will, of course, depend on such factors as the surface tension characteristics of the cosurfactant, the type and amounts of the complex and perfumes, and the type and amounts of any other additional ingredients which may be present in the composition and which have an influence on the thermodynamic factors enumerated above. Generally, amounts of cosurfactant in the range of from 0 to 25 wt. %, preferably from 0.5 wt. % to 15 wt. %, especially preferably from 1 wt. % to 7 wt. %, provide stable microemulsions for the above-described levels of primary surfactants and perfume and any other additional ingredients as described below.
As will be appreciated by the practitioner, the pH of the final microemulsion will be dependent upon the identity of the cosurfactant compound, with the choice of the cosurfactant being effected by cost and cosmetic properties, particularly odor. For example, microemulsion compositions which have a pH in the range of 1 to 10 may employ either the class 1 or the class 4 cosurfactant as the sole cosurfactant, but the pH range is reduced to 1 to 8.5 when the polyvalent metal salt is present. On the other hand, the class 2 cosurfactant can only be used as the sole cosurfactant where the product pH is below 3.2. However, where the acidic cosurfactants are employed in admixture with a glycol ether cosurfactant, compositions can be formulated at a substantially neutral pH (e.g., pH 7xc2x11.5, preferably 7xc2x10.2).
The ability to formulate neutral and acidic products without builders which have grease removal capacities is a feature of the present invention because the prior art o/w microemulsion formulations most usually are highly alkaline or highly built or both.
The final essential ingredient in the inventive hard surface cleaning compositions is water. The proportion of water in the microemulsion compositions generally is in the range of 60 wt. % to 97 wt. %, preferably 80 wt. % to 97 wt. % of the usual diluted o/w microemulsion composition.
The present invention also relates to a stable neutral microemulsion or acidic microemulsion composition comprising approximately by weight:
(a) 0.1 to 20% of a charged complex as previously herein defined;
(b) 0 to 1.5% of a fatty acid;
(c) 1 to 25% of a cosurfactant;
(d) 0.4 to 5% of a water insoluble hydrocarbon or perfume;
(e) 0 to 10% of at least one dicarboxylic acid;
(f) 0 to 1% of phosphoric acid;
(g) 0 to 0.2% of an aminoalkylene phosphoric acid;
(h) 0 to 5% of magnesium sulfate heptahydrate; and
(i) the balance being water.
The present invention also relates to a light duty liquid composition or light duty liquid microemulsion composition which comprises approximately by weight:
(a) 0.1% to 20% of the previously defined charged complex;
(b) 0 to 5% of a perfume, an essential oil or a water insoluble hydrocarbon;
(c) 0 to 25% of a cosurfactant; and
(d) the balance being water.
In addition to the above-described essential ingredients required for the formation of the all purpose cleaning or microemulsion composition, the compositions of this invention may often and preferably do contain one or more additional ingredients which serve to improve overall product performance.
One such ingredient is a source of acidity such as hydrochloric acid or sulfuric acid for use in the formation of toilet bowl cleaners.
Another optional ingredient for use herein is an inorganic or organic salt of oxide of a multivalent metal cation, particularly Mg++. The metal salt or oxide provides several benefits including improved cleaning performance in dilute usage, particularly in soft water areas, and minimized amounts of perfume required to obtain the microemulsion state. Magnesium sulfate, either anhydrous or hydrated (e.g., heptahydrate), is especially preferred as the magnesium salt. Good results also have been obtained with magnesium oxide, magnesium chloride, magnesium acetate, magnesium propionate and magnesium hydroxide. These magnesium salts can be used with formulations at neutral or acidic pH since magnesium hydroxide will not precipitate at these pH levels.
Although magnesium is the preferred multivalent metal from which the salts (inclusive of the oxide and hydroxide) are formed, other polyvalent metal ions also can be used provided that their salts are nontoxic and are soluble in the aqueous phase of the system at the desired pH level.
Thus, depending on such factors as the pH of the system, the nature of the surfactant-polymer complex and cosurfactant, as well as the availability and cost factors, other suitable polyvalent metal ions include aluminum, copper, nickel, iron, calcium, etc. It should be noted, for example, that with the preferred fluoroalkyl sulfonate anionic detergent calcium salts will precipitate and should not be used. It has also been found that the aluminum salts work best at pH below 5 or when a low level, for example 1 weight percent, of citric acid is added to the composition which is designed to have a neutral pH. Alternatively, the aluminum salt can be directly added as the citrate in such case. As the salt, the same general classes of anions as mentioned for the magnesium salts can be used, such as halide (e.g., bromide, chloride), sulfate, nitrate, hydroxide, oxide, acetate, propionate, etc.
The proportion of the multivalent salt generally will be selected so that at the appropriate weight ratio between the anionic surfactant and the polymer to deliver desired performance from the surfactant-polymer mixture in terms of adsorption properties on hard surfaces and soil antiattachment on treated hard surfaces, the physical stability of the total composition is kept, that can be impaired due to an increased hydrophobicity of the anionic surfactant in the presence of multivalent salt instead of alkali metal cation such as the sodium salt thereof. As a consequence, the proportion of the multivalent salt will be selected so that the added quantity will neutralize from 0.1 to 1.5 equivalents of the anionic surfactant, preferably 0.9 to 1.4 equivalents of the acid form of the anionic surfactant. At higher concentrations of anionic surfactant, the amount of multivalent salt will be in range of 0.5 to 1 equivalents per equivalent of anionic surfactant.
The hard surface cleaning compositions can optionally include from 0 to 1.5 wt. %, preferably from 0.1 wt. % to 1.0 wt. % of the composition of a C8-C22 fatty acid or fatty acid soap as a foam suppressant. The addition of fatty acid or fatty acid soap provides an improvement in the rinseability of the composition whether applied in neat or diluted form. Generally, however, it is necessary to increase the level of cosurfactant to maintain product stability when the fatty acid or soap is present. If more than 1.5 wt. % of a fatty acid is used in the instant compositions, the composition will become unstable at low temperatures as well as having an objectionable smell.
As example of the fatty acids which can be used as such or in the form of soap, mention can be made of distilled coconut oil fatty acids, xe2x80x9cmixed vegetablexe2x80x9d type fatty acids (e.g. high percent of saturated, mono-and/or polyunsaturated C18 chains); oleic acid, stearic acid, palmitic acid, eiocosanoic acid, and the like, generally those fatty acids having from 8 to 22 carbon atoms being acceptable.
The all-purpose liquid cleaning or microemulsion composition of this invention may, if desired, also contain other components either to provide additional effect or to make the product more attractive to the consumer. The following are mentioned by way of example: Colors or dyes in amounts up to 0.5% by weight; bactericides in amounts up to 1% by weight; preservatives or antioxidizing agents, such as formalin, 5-chloro-2-methyl-4-isothaliazolin-3-one, 2,6-di-tert.butyl-p-cresol, etc., in amounts up to 2% by weight; and pH adjusting agents, such as sulfuric acid or sodium hydroxide, as needed. Furthermore, if opaque compositions are desired, up to 4% by weight of an opacifier may be added.
In final form, the all-purpose cleaning or clear microemulsions exhibit stability at reduced and increased temperatures. More specifically, such compositions remain clear and stable in the range of 4xc2x0 C. to 50xc2x0 C., especially 10xc2x0 C. to 43xc2x0 C. Such compositions exhibit a pH in the acid or neutral range depending on intended end use. The liquids are readily pourable and exhibit a viscosity in the range of 6 to 60 milliPascalxc2x7Second (mPas.) as measured at 25xc2x0 C. with a Brookfield RVT Viscometer using a #1 spindle rotating at 20 RPM. Preferably, the viscosity is maintained in the range of 10 to 40 mPas.
The compositions are directly ready for use or can be diluted as desired and in either case no or only minimal rinsing is required and substantially no residue or streaks are left behind. Furthermore, because the compositions are free of detergent builders such as alkali metal polyphosphates they are environmentally acceptable and provide a better xe2x80x9cshinexe2x80x9d on cleaned hard surfaces.
When intended for use in the neat form, the liquid compositions can be packaged under pressure in an aerosol container or in a pump-type sprayer for the so-called spray-and-wipe type of application.
Because the compositions as prepared are aqueous liquid formulations and since no particular mixing is required to form the all purpose cleaning or microemulsion compositions, the compositions are easily prepared simply by combining all the ingredients in a suitable vessel or container. The order of mixing the ingredients is not particularly important and generally the various ingredients can be added sequentially or all at once or in the form of aqueous solutions of each or all of the primary detergents and cosurfactants can be separately prepared and combined with each other and with the perfume. The magnesium salt, or other multivalent metal compound, when present, can be added as an aqueous solution thereof or can be added directly. It is not necessary to use elevated temperatures in the formation step and room temperature is sufficient.
The instant all purpose cleaning or microemulsion composition explicitly exclude alkali metal silicates and alkali metal builders such as alkali metal polyphosphates, alkali metal carbonates, alkali metal phosphonates and alkali metal citrates because these materials, if used in the instant composition, would cause the composition to have a high pH as well as leaving residue on the surface being cleaned.
It is contemplated within the scope of the instant invention that the instant charged surfactant-polymer complex can be employed in hard surface cleaning compositions such as wood cleaners, window cleaners and light duty liquid cleaners.
The following examples illustrate liquid cleaning compositions of the described invention. Unless otherwise specified, all percentages are by weight. The exemplified compositions are illustrative only and do not limit the scope of the invention. Unless otherwise specified, the proportions in the examples and elsewhere in the specification are by weight.


An interference filter having a layer with an area consisting of a porous material extending from the surface of the layer to the interior, the dimensions of the porous layer area in a direction normal to the layer surface have different values to provide for varying reflection or, respectively, transmission characteristics.

The invention relates to a layer with a porous area for use, for example, in an interference filter. The invention further relates to a process of manufacturing such a layer.
Porous silicon (PS) is known which, because of its compatibility with the highly developed Si-microelectronics and because it is easy and inexpensive to manufacture, is a promising material for use as sensors (M. Thust et al., Meas. Sci. Technol. 6, (1995), as well as Y. Duvault-Herrera et al., colloid. Surf., 50,197, (1990) and, because of its electroluminescence, is suitable for applications in the area of display technology (P. Steiner et al., Appl. Phys. Lett., 62(21), 2700, (1993). Furthermore, porous silicon is known to be used in connection with color-sensitive photo detectors (M. Krxc3xcger et al., EMRS 96, Thin Solid films) or passive reflection filters.
The manufacture of layer systems of PS has been demonstrated (M. G. Berger et al., J. Phys. D: Appl. Phys. 27, 1333, (1994), DE P 43 19 413.3 or M. G. Berger et al., Thin Solid Films, 255, 313, (1995)). These layer systems exhibit for example, a color-selective reflectivity depending on the manufacturing parameters. Furthermore, the structured manufacturing of PS is known, whereby areas with different spectral behavior an be made (M. Krxc3xcger et al., EMRS 95, Thin Solid films).
Specifically, porous silicon consists of a foam-like skeleton of silicon crystallites, which include pores. The size of the crystallites and of the pores varies, depending on the doping and the manufacturing parameters, between some nanometers and some micrometers. If the wave length of the light is much greater than the structures in the PS, the PS appears to the light to be a homogeneous material (xe2x80x9ceffective mediumxe2x80x9d) and its properties can therefore be described by an effective refraction index (W. Theiss: The Use of Effective Medium Theories in Optical Spectroscopy, in Festkxc3x6rperprobleme/Advances in Solid State Physics, Volume 33, page 149, Vieweg, Braunschweig/Wiesbaden), which depends on the refraction indices of the silicon crystallite, an oxide possibly present on the surface of the crystallite and of the material in the pores. Consequently, interference filters can be constructed from various porous layers, which extend parallel to one another and have different optical properties. The various layers are constructed parallel to one another and have, within the respective layer, a constant layer thickness normal to the layer surface. It is however disadvantageous that for each of the different spectral characteristics, a separate filter must be made in separate manufacturing steps.
It is also disadvantageous that, in the known methods, the manufacture of adjacent filters with different characteristcs can be achieved only by photolithographic steps, or respectively, by separate etching of the filters with particular characteristics.
It is therefore the object of the invention ti provide a layer including a porous layer and an interference filter including such a layer as well as a process of manufacturing such an interference filter wherein a simplified establishment of interference filter functions of porous silicon with laterally gradually variable reflection and transmission characteristics is achieved.
In an interference filter having a layer with an area consisting of a porous material extending from the surface of the layer to the interior, the dimensions of the porous layer area in a direction normal to the layer surface have different values to provide for varying reflection or, respectively, transmission characteristics.
It has been found that, based on the well known manufacture of layer systems of porous silicon, a method could be provided wherein a lateral change of the reflection and transmission capabilities is achieved.
In particular, a layer system with a well-defined laterally variable spectral characteristic is manufactured thereby in a single process step. In this process, a porous layer area is so formed that the porous layer thickness assumes different values within this layer. In this way with such a porous area adjustable characteristics within this single layer can be achieved depending on desired boundary conditions. It is no longer necessary to manufacture several components individually which have different characteristics and which are then combined.
Furthermore, it may be advantageous to provide within the porous area several different porosity values in order to provide for individually desired characteristics in a controllable manner. Also, the degree of porosity may be established laterally for example in a continuous way. The area furthermore may have several partial layer areas with different degrees of porosity.
For a simplified manufacture, it may be advantageous to form the porous layer and/or the partial layer areas such that they are wedge-shaped. Preferably Al, GaAs, or SiGe are suitable materials, but most advantageous is the silicon which is used in many ways in microelectronics.
It has been realized that it is advantageous to establish during the manufacture of such a layer, upon etching for making the material porous, a gradient with respect to a physical value which corresponds to the etching velocity of such an etching procedure. Alternatively, or additionally, a value can be selected which corresponds to the porosity of the material. As physical value, preferably the electric field is employed and, the temperature is used. The material of the substrate or the doping of the material may be employed. The values may be employed individually or in combination together.
It is advantageous to utilize the electrodes provided for the electrochemical etching for the formation of the field gradient. In this case, a first electrode may be arranged in the electrolyte disposed above the surface to be etched, whereas a second electrode is disposed on the side of the substrate remote from this surface. Furthermore, such an electrode may be arranged in a tilted fashion so as to form a field gradient. Furthermore, the electrode or electrodes may be in the form of a net and may include a mesh structure to form gradients wherein the mesh openings are increasingly narrower in the direction of the gradient.
The layer system according to the invention can be made for example by current flow with a lateral gradual change of the reflection or respectively, transmission characteristic utilizing the temperature dependency of the etching process. As a result of the temperature dependency, the etching rate or, respectively, the porosity changes when the temperature of the electrolyte/substrate changes. Consequently, temperature gradients in the electrolyte or in the substrate can change locally the etching rate and, as a result, also the optical properties of a filter.
Alternatively, the layer system according the invention can be made with a laterally gradual change of the reflection and or, respectively, transmission characteristics utilizing a changed anode or, respectively, cathode arrangement. As a result of the dependency of the etching process on the field strength between the anode and the cathode, the etching rate or, respectively, porosity is changed between the electrodes. Consequently, field strength gradients may change the etching rate between the electrodes and consequently also the optical properties of a filter.
The invention however is not limited to such processes. In accordance with the invention, alternative processes are possible wherein another value, which affects the etching process, is used to achieve a gradual change of the porosity. For example, the doping of the substrate material before the etching may be so selected that there is a lateral gradient in the substrate.
The invention is explained below in greater detail on the basis of figures and embodiments.

Method for the production of a porous layer