AQUEOUS LIQUID CLEANING FORMULATION
Field of the Invention This invention relates generally to a solvent composition for use in a liquid soap formulation. In particular, the present invention is directed to a solvent composition which provides high cleaning efficacy for the removal of oil-based ink, oil-based paint, and the like.
Background of the Invention The present invention is directed to a solvent composition comprising d-limonene and dibasic esters in a liquid soap formulation. The solvent combination of the present invention exhibits a synergistic effect, unexpectedly making the liquid cleaning composition more effective for removing oil-based ink, oil-based paint, and the like, than cleaning formulations containing either d-limonene or dibasic esters alone.
In the past, organic solvents such as d-limonene, isopars, odorless mineral spirits, mineral oil, soy oil, monoesters, diesters, and others were commonly used, either individually or in combination, for cleaning grease, tar, paint, ink, and other heavy soils. For example, U.S. Patent No. 4,867,800, to Dishart. et al., disclose a cleaning composition comprising a terpene and dibasic ester combination with particular suitability for removal of solder flux from the surface of printed circuit boards. However, the concentration of the solvent combination used is high, requiring 80% by weight terpene hydrocarbons and 20% by weight dibasic esters.
Likewise, a cleaning agent useful for industrial cleaning with a citric oil composition is disclosed in U.S. Patent 4,620,937, to Dellutri. The citric oil in the cleaning agent is mainly distilled d-limonene.
U.S. Patent No. 4,511 ,488, to Matta. discloses an aqueous cleaning composition containing d-Iimoπene combined with anionic, non- ionic, or mixed anionic-nonionic surfactants. The composition disclosed by Matta is useful for heavy industrial cleaning tasks. In U.S. Patent No. 4,414,128 to Goffinet. a liquid detergent composition is disclosed which incorporates a mono-or sesquiterpeπe material in combination with a polar solvent to provide cleaning characteristics especially useful to remove greasy or oily soils in inorganic particulate soils. Finally, U.S. Patent No. 5,736,500 to Farnsworth et al. discloses a surfactant-oil microemulsion useful as a cleaning composition for hard surfaces. The composition of Farnsworth et al. contains a surfactant system, comprising at least one alkoxylated alcohol nonionic surfactant, a solvent, and a water-insoluble oil which is a solvent for fats. Conventional liquid cleaning compositions still suffer from a number of drawbacks. Cleaning agents which are extremely mild, and thereby avoid irritation and toxicity, are generally ineffective at removing grease, paint, and similar stains and grime. Cleaning agents which are effective in cleaning greasy or oily soils, like oil-based ink and oil-based paint, require strong ingredients which irritate the user's skin, and may even be toxic to the user and to the environment. Additional disadvantages of prior art solvent compositions include flammability and water-immiscibility.
It is now been discovered that the defects of prior art cleaning compositions can be minimized or overcome by incorporating a solvent combination into an aqueous cleaning composition. The solvent combination unexpectedly exhibits a synergistic effect, such that the solvent combination cleans more effectively than a formulation containing either ingredient alone. Because of the synergistic effect, the solvent
concentration required to effectively clean greasy and oily soils is significantly reduced. Furthermore, the solvent combination is mild enough to be used as a personal cleaning agent, while still effective enough to be used as an all-purpose heavy-duty cleaner, to remove grease, oil-based paint, oil-based ink, and the like, from hard surfaces, such as in paint shops, print shops, and on printing plates.
Summary of the Invention According, it is an object of the present invention to provide an improved heavy-duty cleaning composition useful as a personal cleaner. Another object of the present invention is to provide a cleaning composition mild enough to be used as a hand cleaner, in addition to being effective as a heavy duty cleaning agent.
Still another object of the present invention is to provide a cleaning composition which can be used to remove oil-based ink, oil-based paint, grease, grime, and the like, without damaging the original surface being cleaned.
A further object of the present invention is to provide a solvent combination which exhibits a synergistic effect such that the solvent combination cleans with greater efficacy than a formulation containing either solvent alone.
Yet a further object of the present invention is to provide a heavy duty cleaning composition comprising a solvent combination which is environmentally safe.
The present invention provides a solvent combination for use in an aqueous liquid cleaning formulation. The solvent combination provides a cleaning formulation with high cleaning efficacy for the removal of oil- based ink, oil-based paint, and the like. The cleaning composition of the present invention is effective both as a personal cleaner and as an all- purpose cleaner, to remove grease, grime, oil-based paint, oil-based ink,
and the like. As used herein, a personal cleaner refers to a cleaner which can be used on the hands, or on other parts of the body, for the removal of oil-based paint, oil-based ink, grease, and the like.
In particular, the present invention is directed to a solvent combination comprising d-limonene and dibasic esters. The solvent combination unexpectedly exhibits a synergistic action, providing greater cleaning efficacy than is provided by a cleaning composition containing either component alone. The composition can further include preservatives, abrasives, emollients, humectants, surfactants, and the like.
Detailed Description of the Preferred Embodiment Reference now will be made in detail to the embodiments of the invention, one or more examples of which are set forth below. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment, can be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention cover such modifications and variations as come within the scope of the appended claims and their equivalents. Other objects, features and aspects of the present invention are disclosed in or are obvious from the following detailed description. It is to be understood by one of ordinary skill in the art that the present discussion is a description of exemplary embodiments only, and is not intended as limiting the broader aspects of the present invention.
The present invention encompasses an aqueous, heavy-duty liquid cleaning formulation. The aqueous, liquid cleaning formulation of the present invention utilizes a solvent combination comprising d-limonene
and dibasic esters to provide a heavy-duty liquid cleaning formulation that unexpectedly provides high cleaning efficacy for the removal of oil-based ink, oil-based paint, grease, and the like.
As used herein, the term "solvent" refers to a material that dissolves another substance while not changing its physical state. In the present invention, it is not required that the solvent be the majority component of the resultant solution. Examples of solvents include synthetic and natural hydrocarbons. Synthetic and natural hydrocarbons may include dibasic esters, terpenes like d-limonene, mixtures of isoprenoid and mineral oil substances, naphthas, glycol ethers, parrafinic and isoparrafinic hydrocarbons, aromatic hydrocarbons, petroleum distillates, vegetable oils, animal oils, organic halides, halogenated solvents, and alcohols.
As used herein, the term "dibasic ester" refers to an ester containing two hydrogens that may be replaced by a monovalent metal or radical. Examples of dibasic esters include dimethyl gluterate, dimethyl adipate, and dimethyl succinate.
Generally speaking, aqueous, heavy-duty liquid cleaning formulations refer to liquid soaps containing solvents which are useful for the removal of grease, oil-based paint, oil-based ink, paint, and similar stains and grime. The formulation may be typically applied to the skin, with or without water, worked into a lather, and then rinsed off with water. Alternatively, aqueous, heavy-duty liquid cleaning formulations may be used to apply to a hard surface for the removal of paint, grime, ink, and the like, without damaging the underlying surface.
The aqueous, heavy-duty liquid cleaning formulation of the present invention is comprised of: 1) a solvent combination comprising a mixture of d-limonene and one or more dibasic esters; 2) a surfactant system
composed predominately of non-ionic, anionic and/or amphoteric surfactants or combinations thereof; and 3) a carrier.
As used herein the term "surfactant" refers to a surface-active substance which can alter the surface tension of water. Surfactant compositions, which usually act to reduce the surface tension of water, are of three types: nonionic, anionic and cationic.
As used herein the term "carrier" refers to a liquid substance that supports another substance. In addition, a carrier may have other properties, such as cleaning properties, and particularly, may also act as the surfactant component of the present invention.
Embodiments of the present invention may also contain one or more conventional formulating components including, but not limited to abrasives, such as pumice, thickeners, preservatives, humectants, emollients, and combinations thereof. The solvent portion of the present invention comprises a mixture of dibasic esters and d-limonene. Dibasic esters used typically include dialkyl esters of dicarboxylic acids (dibasic acids). Dibasic esters are capable of undergoing reactions of the ester group, such as hydrolysis and saponification. Hydrolysis of dibasic esters at low and high pH typically produces the corresponding alcohols and dibasic acids or acid salts. Typical dibasic esters include dimethyl adipate, dimethyl gluterate, dimethyl succinate, and mixtures thereof. Other esters with longer chain alkyl groups derived from alcohols, such as methyl, ethyl, propyl, isopropyl, amyl and butyl can be employed. The acid portion of these esters may also be derived from other dibasic acids, such as oxalic, malonic, suberic, and pimelic acids and mixtures thereof.
Mixtures of dibasic esters are available commercially. For example, SANTOSOL (Monsanto, St. Louis, MO), a dibasic ester mixture comprising dimethyl gluterate (59 - 73 % weight); dimethyl succinate (17 -
25 % weight); dimethyl adipate (10 - 14 % weight) and methyl alcohol (0 - 0.2 %), may be used as the source of dibasic esters in the present invention. DuPont (Wilmington, DE) also provides a commercial product called DBE, containing a mixture of dibasic esters, which is equally useful as the source of dibasic esters in the present invention. DuPont's product comprises dimethyl gluterate (55 - 65 % weight); dimethyl adipate (10 - 25 % weight); and dimethyl succinate (15 - 25 % weight).
The concentration of dibasic esters as embodied by the present invention ranges from about 5 % to about 15 %; preferably from about 7 % to about 10 %; and most preferably about 9 %. The percentages expressed in the foregoing ranges refer to the ratio of the weight of a particular component to the total weight multiplied by 100. As an example, a liquid cleaning formulation containing 40 grams of a solvent dissolved into 100 grams total weight may be expressed as 40 % solvent.
In the present invention, d-limonene is used as the second component of the solvent combination. D-limoπene is derived from the rinds or peels of citrus fruits, such as oranges, lemons and grapefruits. The d-limonene employed in the composition of the present invention was obtained from Givaudan-Roure Corporation (Clifton, New Jersey), although it is to be recognized that other commercial d-limonene preparations are available which meet the following specifications:
The concentration of d-limonene in the solvent combination of the present invention ranges from about 15 %- to about 30 %, preferably from about 18% to about 25%, and most preferably about 21 %.
In addition to the solvent combination, the aqueous, heavy-duty liquid cleaning formulation of the present invention contains a surfactant system and a carrier. The surfactant system may be composed predominately of non-ionic, anionic and/or amphoteric surfactants or combinations thereof, well known to those of ordinary skill in the art. While it is desirable to use predominately nonionic and/or amphoteric surfactants in the liquid cleaning formulation of the present invention, it should be understood that the present invention contemplates formulations containing predominately nonionic and/or amphoteric surfactants balanced with relatively small amounts if anionic and/or cationic surfactants such that the presence of the anionic and/or cationic surfactants does not affect the mildness of the formulation.
Exemplary non-ionic surfactants include, but are not limited to, PLURAFAC (BASF Corp., Spartanburg, SC); NEODOL (Shell Chemical Company, Houston, TX); and TRITON (Rohm and Hass, Springhouse, PA). Exemplary amphoteric surfactants include, but are not limited to, cocamphocarboxypropionate, cocamphocarboxy propionic acid, cocamphoacetate and cocamphodiacetate. Generally speaking, commercially available amphoteric surfactants of this type are made and sold in the form of electroneutral complexes with, for example, hydroxide counterions or with anionic sulfate of sulfonate surfactants. Suitable commercial products include, but are not limited to, products sold under the trade names of EMPUGEN (Albright & Wilson); MIRANOL (Rhone- Pouleπc); ALKATERIC (Alkaπ'l Chemicals); AMPHOTERGE (Lonza, Inc.);
MONATERIC (Mona Industries); REWOTERIC (Rewo Chemical Group); and SCHERCOTIC (Scher Chemicals).
Exemplary anionic surfactants include, but are not limited to ethoxylated alkyl sulfates, alkyl glyceryl ether sulfonates, methyl acyl taurates, fatty acyl glycinates, alkyl sulfiosuccinates, alpha-sulfonated fatty acids, their salts and/or their esters, alkyl ethoxy carboxylates and mixtures thereof.
The surfactant systems may be composed of a combination of surfactants. For example, the surfactant systems may be composed of a mixture of one or more anionic surfactants with nonionic, amphoteric and/or betaine surfactants. Various conventional surfactant systems are commercially available and are known to those of skill in the art.
Suitable surfactant systems include MIRACARE MS-1 (available from Rhone-Poulenc, Cranbury, New Jersey), STANDAMID KDO (Henkel Corp., Hoboken, NJ), COLONIAL AGENT 230 (Colonial Chemical, Inc.,
Chattanooga, Tennessee), TWEEN 85 (ICI Americas, Wilmington, Delaware), and STANDAMOX CAW (Henkel Corp., Hoboken, NJ), and combinations thereof. MIRACARE MS-1 includes PEG 90 sorbitan laurate, sodium trideceth sulfate, PEG 150 distearate and lauroamphodiacetate in a water base (approximately 60%, by weight, water). STANDAMOX CAW includes cocamidopropylamine oxide in a water base (approximately 70%, by weight, water). It is contemplated that other individual surfactants and/or surfactant systems noted for their mildness may be used. Other suitable surfactant systems may include components such as, for example, sodium cocoyl isothionate, sodium laureth sulfate, ammonium sulfate, cocamidoproply betaine, ammonium lauryl sulfate, PEG 80 sorbitan laurate, PEG 20 sorbitan trioleate, and/or sodium trideceth sulfate.
According to the present invention, at least one nonionic surfactant and/or amphoteric surfactant is combined with the other components. Of course, a predominately nonionic and/or amphoteric system may be used. The surfactant/surfactant system should be a nonionic surfactant and/or amphoteric surfactant that is mild to the skin and induces significantly less redness and dryness and is less disruptive to the statum corneum. It is contemplated that some anionic and/or cationic surfactants may be blended with the nonionic and/or amphoteric surfactants as long as they do not affect the mildness of the formulation. For example, the weight ratio of anionic surfactant: amphoteric surfactant is generally in the range from about 1 :5 to about 20:1. As another example, the weight ratio may be from about 1 :2 to about 5:1. As yet another example, the weight ratio may be from about 1 :2 to about 2:1. Generally speaking, the total level of surfactants may be from about 5% to about 60% of the weight of the formulation. For example, the total level of surfactants may generally be from about 5% to 40%, desirably from about 8% to about 25%, and more desirably from about 10% to about 30%, of the weight of the formulation.
Generally speaking, the carrier used for the formulations of the present invention is water. However, other carriers are well-known to those of ordinary skill in the art. It should be understood that the present invention contemplates the use of carriers other than water. The carrier may include viscosity modifiers, thickeners, colorants, fragrances, emollients, buffers, and/or pH control agents. For example, an exemplary thickener additive is available commercially as PRIMAFLO (Aqualon, Wilmington, Delaware). Additionally, one or more other conventional formulating components may be combined in the carrier portion of the liquid cleaning composition of the present invention. For example, abrasives, preservatives, humectants, solvents, emollients and the like, may be combined with the conventional formulating components. For
example, an exemplary additive to the carrier is polyquaternium-10, available under the trade name POLYMER UCARE JR 400 from Amerchol (Edison, New Jersey).
Useful humectants include, for example, glycerine. Useful abrasives include, for example, pumice. Useful preservatives include, for example, DMDM Hydantoin, which is available under the trade name GLYDANT XL 1000 (Lonza, Inc., Fairlawn, New Jersey). Preservative enhancers such as, for example, Tetrasodium ETDA may also be added to the formulation. An exemplary formulation may originate as a water phase, a surfactant phase, and a solvent phase, which are blended together utilizing conventional mixing techniques to produce the aqueous liquid cleaning formulation of the present invention.
In such an exemplary formulation, the water phase may be composed of sterile, de-ionized water and may include additives such as, for example, viscosity modifiers, abrasives, thickeners, colorants, fragrances, emollients, buffers, and/or pH control agents.
The surfactant phase may contain one or more nonionic or amphoteric surfactants or surfactant systems. It is contemplated that the surfactant phase may include minor amounts of cationic or anionic surfactants. Desirably, in such an exemplary formulation, surfactant systems such as, for example, MIRACARE MS-1 , STANDAMOX CAW, STANDAMID KDO, COLONIAL AGENT 230, and the like, may be employed. In an exemplary formulation, the solvent phase contains the solvent combination comprising d-limonene and dibasic esters. In a preferred embodiment of the present invention, it has been found that the combination of 21 % d-limonene and 9% dibasic esters may be the most effective.
The present invention may be better understood with reference to the following examples:
EXAMPLE 1
The following is one procedure that may be used in order to produce liquid cleaning formulations according to the present invention. Liquid cleaning formulations A, B, and C were prepared as follows:
The solvent phase is prepared by mixing TWEEN 85, d-limonene, and dibasic esters at room temperature (approximately 25° C). In a separate vat, the water phase is prepared by adding the following ingredients in the order listed: water, GLYDANT, and PRIMAFLO. The water phase is mixed until the resulting solution is thick and clear. Subsequently, during continous mixing, STANDAMID KDO and AGENT230 are added to the water phase. The water phase is again mixed until thick and clear, at which time the solvent phase, containing TWEEN 85, d-limonene, and dibasic esters, is added to the water phase. The resulting solution is mixed until smooth, and the pumice added. Other desired additives, such as viscosity modifiers, other abrasives, thickeners, colorants, fragrances, emollients, buffers, and/or pH control agents, may also be added at this
step. The solution is mixed well, so the abrasive is evenly dispersed, and the formula dispeπdsed into containers, such as bottles or bag-in-a-box.
EXAMPLE 2 The cleaning formulations prepared in Example 1 were then tested for cleaning efficacy. After cleaning, the soil removal percent was calculated by comparing measurements taken prior to and after soiling. The equipment used included a GARDNER ABRASION TESTER apparatus manufactured by BYK Gardner (Columbia, Maryland) and a CR-310 CHROMA METER™ reflectometer manufactured by Minolta of
101 Williams Drive, Ramsey, NJ 07446. Furthermore, the tiles used were vinyl flooring tiles manufactured by Armstrong World Industries of Lancaster, PA 17604. Also, towels were used during the cleaning of the tiles. These towels are sold under the trade designation WORKHORSE™ Rag Number 41200, manufactured by Kimberly-Clark Corporation, of 200
Bay Bridge Road, Mobile, AL 36610.
Soils tested included an oil-based printer's ink and an oil-based paint. The test procedure for a trial run included testing each cleansing formulation with each soil in triplicate on about a 30.48 centimeter (hereinafter may be referred to as "cm") by about a 7.62 cm rectangular tile. The tests were conducted on a smooth, finished tile side. Each tile was cleaned with a multipurpose cleaner and allowed to air dry prior to the initial reflectometer measurements.
After standardizing the reflectometer, initial readings were taken and marked using a template. Afterwards, three tiles were soiled for each cleansing product and soil combination. The applied soil was spread evenly in circular strokes across the tile surface, and finished with smooth, even lengthwise strokes. Afterwards, the soil was allow to cure for about 18 hours.
After curing, three reflectometer readings were taken of each tile at the same positions as the initial readings by using the template. After the readings, the tiles were cleaned in a GARDNER ABRASION TESTER™ apparatus. A rectangular WORKHORSE™ towel having dimensions of about 17 cm by about 34 cm was cut in about half and wrapped around a wooden block with its smooth side facing the block. Two grams of a cleaning formulation was applied to the towel for each test and the block was mounted in the tester. Each soiled tile was clamped into a pan facing the block. The tester was run for 50 cycles. After 50 cycles, the towel was removed and about half of a clean towel without cleaning formulation was wrapped on the block and run for 5 cycles. Afterwards, the tile was removed and three measurements were taken with the reflectometer at the same positions as before using the template.
The percent of soil removal was calculated using the following formula:
(Rc - Rs)/(Ri - Rs) * 100%
where Re = Cleaned Tile Reflectance; Rs = Soiled Tile Reflectance; and Ri = Initial Tile Reflectance. Three readings were taken on each tile, and each soil and cleaning product combination was applied to three tiles. Thus, nine readings were taken for each soil and cleansing product combination. The mean of the nine readings was reported for each cleansing product and soil combination, thus completing the data compiling for the first trial run. Afterwards, a second trial run was completed and the data was compiled using the same procedure as described above to confirm the first trial run data. The readings from the first and second trial runs were averaged to compare the percent cleaning of each cleansing product.
Results of cleaning performance are summarized as follows:
Cleaning formulation A, containing 21 % d-limonene and 9% dibasic esters as the solvent phase, was significantly more effective in removing both oil-based paint and oil-based ink from the tiles than cleaning formulations containing either d-limonene (30%) or Dibasic esters (30%) alone (formulation B and C respectively).
The cleaning agent of the present invention has been found most useful in heavy duty cleaning such as for the removal of oil-based paint, oil-based ink, grease, grime, and the like from walls, furniture, and other surfaces. In an alternative embodiment the solvent combination of the present invention can be blended with surfactants and water to produce a liquid hand soap for use in auto shops, print shops, manufacturing plants, and many other operations, for cleaning hands.
Although preferred embodiments of the invention have been described using specific terms, devices, and methods, such description is for illustrative purposes only. The words used are words of description rather than of limitation. It is to be understood that changes and variations may be made by those of ordinary skill in the art without departing from the spirit or the scope of the present invention, which is set forth in the following claims. In addition, it should be understood that aspects of the various embodiments may be interchanged both in whole or in part. Therefore, the spirit and scope of the appended claims should
not be limited to the description of the preferred versions contained therein.