Field

This invention relates generally to solvents and their use in cleaning compositions. More specifically, the solvents are alkoxylate compounds derived from propylene oxide.

Background

Cleaning compositions are well known and a large number are sold for both industrial and home use. Many cleaning compositions, including for instance hard surface cleaners, typically contain a surfactant, an organic solvent, and water, as well as a variety of other ingredients which may be chosen by the skilled formulator.

Organic solvents are usually present in cleaning compositions to achieve acceptable cleaning of the substrate, for instance for cleaning glass. An appropriate organic solvent having good cleaning efficiency enhances an aqueous cleaning composition's ability to remove soils and dirt which may contain organic matter from the substrate without leaving streaks or residues.

Many organic solvents used in cleaner compositions are volatile organic compounds (VOC) and as such have come under increased regulation in recent years. In California, for instance, the California Air Resources Board (CARB) has set restrictions on the permissible VOC level on various household cleaners. Such regulatory efforts to reduce exposure to VOCs have caused the industry to look for alternatives for cleaning compositions.

One common alternative is to formulate products in very dilute form (high water content), thus reducing the overall amount of VOC solvent in the composition.

Unfortunately, however, products sold in dilute form worsen greenhouse gas emission due to increase fuel consumption during transport. In addition, highly diluting a formulation to reduce its organic solvent content may also reduce the cleaning efficiency that would normally be provided by that solvent. Unsurprisingly, these compositions, when formulated in more concentrated form (less water content), will generally not satisfy the CARB regulations on VOC. There continues to be a need in the industry, therefore, for alternative solutions to the VOC solvent problem.

The problem is addressed by this invention through the provision of zero VOC solvents for use in cleaning compositions. Statement of Invention

We have now found that alkoxylate compounds of formula I as described herein function as excellent solvents for cleaning compositions. Advantageously, the alkoxylates exhibit very low volatility and are therefore suitable for use in zero VOC compositions, including high concentrate compositions, thus allowing formulators to comply with regulatory requirements, including those of CARB. In addition, the solvents of the invention exhibit favorable cleaning properties that render them viable replacements for organic solvents.

High molecular weight alcohol alkoxylates are known as surfactant ingredients in many cleaners; typically alkoxylates of HLB of 3 or higher are used. Because of their generally higher viscosity or their non-liquid form, alcohol alkoxylate surfactants would not have been considered useful as solvents in cleaning applications. Hence, current products formulate these alkoxylates with a low molecule weight organic solvent(s). It was a surprising discovery, therefore, that alkoxylates of formula I can be used as solvents in cleaner compositions, replacing the VOC contributing organic solvents.

Accordingly, in one aspect of the invention, there is provided a cleaning

composition comprising: a surfactant component; and a solvent component comprising an alkoxylate of formula I:

R-0-(PO) _n -H (I)

wherein R is linear or branched C8-C ₁₀ alkyl, PO is propyleneoxy, and n is from 3 to 7.

In another aspect, there is provided a method of cleaning a substrate (e.g., a hard surface, clothing, or body parts such as hands or hair), the method comprising applying to the substrate the cleaning composition described herein.

Detailed Description

Unless otherwise indicated, numeric ranges, for instance as in "from 2 to 10," are inclusive of the numbers defining the range (e.g., 2 and 10).

Unless otherwise indicated, ratios, percentages, parts, and the like are by weight. "Propyleneoxy" refers to -CH ₂ -CH(CH ₃ )-0- or -CH(CH ₃ )-CH ₂ -0-.

"Zero VOC composition" and like terms mean a composition in which all components, except water, have vapor pressure < 0.1 mmHg at 20 °C. A material is classified as being zero VOC if it exhibits a vapor pressure of < 0.1 mmHg at 20 °C.

Conversely, a material is classified as being a VOC contributor if it has a vapor pressure of 0.1 mmHg or greater at 20 °C, and all VOC contributors will be counted by weight present in a formulation.

As noted above, the invention provides a cleaning composition containing a surfactant component and a solvent component. The solvent component is an alkoxylate of formula I:

R-0-(PO) _n -H (I)

wherein R is linear or branched C8-C ₁₀ alkyl, PO is propyleneoxy, and n is a number from 3 to 7.

Formula I includes the variable "n." This variable represent an average degrees of propoxylation in an oligomer distribution and is determined from the relative mole amounts of the alcohol and propylene oxide starting materials used in the synthesis of the alkoxylate. In some embodiments, n is from 4 to 6, alternatively n is 5.

In some embodiments of the invention, R in the alkoxylate of formula I is branched C ₈ -C ₁₀ alkyl.

In some embodiments, R is 2-ethylhexyl (CHsCHaCHaCHaCHCCHaCI^CHa-). In some embodiments, R is 2-propylheptyl (CHsCHaCHaCHaCHaCHCCHaCHaCI^CHa-).

A preferred alkoxylate of formula I is 2EH-0-(PO)5-OH, wherein 2EH is 2- ethylhexyl. Another preferred alkoxylate of formula I is 2PH-0-(PO)5-OH, wherein 2PH is 2-propylheptyl.

The alkoxylates of formula I of the invention may be prepared by synthetic methods known to those skilled in the art. For example, in a typical procedure, a suitable alcohol or fatty acid alcohol is alkoxylated with propylene oxide. Alkoxylation processes may, for instance, be carried out in the presence of acidic or alkaline catalysts, or by using metal cyanide catalysts. Alkaline catalysts may include, for instance, hydroxides or alcoholates of sodium or potassium, including NaOH, KOH, sodium methoxide, potassium methoxide, sodium ethoxide and potassium ethoxide. Base catalysts are normally used in a

concentration of from 0.05 percent to about 5 percent by weight, preferably about 0.1 percent to about 1 percent by weight based on starting material.

The addition of propylene oxide may, for instance, be carried out in an autoclave under pressures from about 10 psig to about 200 psig, preferably from about 60 to about 100 psig. The temperature of alkoxylation may range from about 30 °C to about 200 °C, preferably from about 100 °C to about 160 °C. After completion of oxide feed, the product is typically allowed to react until the residual oxide is less than about 10 ppm. After cooling the reactor to an appropriate temperature ranging from about 20 °C to 130 °C, the residual catalyst may be left unneutralized, or neutralized with organic acids, such as acetic, propionic, or citric acid. Alternatively, the product may be neutralized with inorganic acids, such as phosphoric acid or carbon dioxide. Residual catalyst may also be removed using ion exchange or an adsorption media, such as diatomaceous earth.

The amount of the formula I alkoxylate solvent used in the cleaning compositions of the present invention will vary depending on the type and amount of other ingredients present, and whether a concentrated or diluted formulation is being prepared. The amount of the alkoxylate needed to achieve an optimum balance between cleaning efficiency and other properties such as cloud point can readily be determined by the skilled formulator. By way of non-limiting example, a diluted (non concentrate) cleaning composition may contain from 0.1 to 50 percent, alternatively 0.1 to 20 percent, by weight of the alkoxylate of formula I based on the total weight of the composition.

In some embodiments, preferred where the cleaning composition is a hard surface cleaner, the diluted composition may for instance contain at least -0.5 percent, alternatively at least 4 percent, by weight of the alkoxylate of formula I based on the total weight of the composition.

In some embodiments, preferred where the cleaning composition is hand dish soap, the diluted composition may for instance contain at least 1 percent, alternatively at least 2 percent, by weight of the alkoxylate of formula I based on the total weight of the

composition.

In some embodiments, preferred where the cleaning composition is laundry detergent, the diluted composition may for instance contain at least 10 percent, alternatively at least 20 percent, by weight of the alkoxylate of formula I based on the total weight of the composition.

The water-based cleaning compositions of the invention may contain other organic solvents in addition to the alkoxylate of formula I. Suitable compounds which may be useful as cosolvents are well known and may include alcohols, glycols, glycol ethers, glycol ether esters, ketones, esters, hydrocarbons, terpenes, and the like. Examples of such compounds include, without limitation, ethanol, propanol, isopropanol, butanol, glycol, ethylene glycol ethyl ether, ethylene glycol propyl ether, ethylene glycol butyl ether, ethylene glycol hexyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether, propylene glycol t-butyl ether and mixtures thereof.

Of course, for low VOC formulations, it is desirable to minimize the inclusion of VOC contributing co-solvents. Thus, in some embodiments, the invention provides cleaning compositions that are substantially free of volatile organic solvents other than the alkoxylate of formula I. By "substantially free" is meant that no more than 5 weight percent, alternatively no more than 3 weight percent, alternatively no more than 1 weight percent, or alternatively no more than 0.1 weight percent, of additional organic solvent is present in the composition, based on the total weight of the alkoxylate of formula I, the surfactant component, and any additional organic solvents.

Surfactants useful in the cleaning compositions of the invention are well known and include anionic, nonionic cationic and amphoteric compounds. Combinations of more than one such surfactant compound may be used in the cleaning compositions of the present invention.

Amphoteric surfactants suitable for use include, for example, betaines, alkyl imidazolines, cocoamphopropionates, disodium cocoamphodipropionate (also known as cocoimidazoline carboxylate), or combinations thereof.

Suitable anionic surfactants for use include alkyl sulfates, alkyl benzene sulfonates, a-olefin sulfonates, alkyl taurates, alkyl sacrosinates, alkyl diphenyloxide disulfonates, alkyl naphthalene sulfonates, alkyl ether sulfates, alkyl ether sulfonates, sulfosuccinates, and other anionic surfactants as known for use in cleaning compositions, including linear Cg_ ₁₆ alkyl sulfates, Cg_ ₁₆ alkyl sulfonates, Cg_ ₁₆ alkyl benzene sulfonates and Cg_ ₁₆ alkyl diphenyloxide disulfonates, decyl sulfophenoxy benzene/oxybis decyl benzene sulfonic acid disodium salt, and sodium octane sulfonate, sodium dodecyl sulfonate, and sodium lauryl sulfate, and combinations of the foregoing. The surfactants are typically available as the alkali metal, alkaline earth and ammonium salts thereof.

Suitable nonionic surfactants for use in the cleaning composition include

alkoxylated alcohols, alkoxylated ether phenols, silicone-based compounds such as silicone glycol copolymers, and semi-polar nonionics such as trialkyl amine oxides.

Cationic surfactants are also available for inclusion, both for cleaning ability and, upon suitable selection, anti-bacterial/germicidal characteristics, e.g. quaternary ammonium compounds. Examples of useful cationic surfactants include N-alkyl trimethyl ammonium chloride, and dimethyl dicoco quaternary ammonium chloride. The amount of surfactant that should be used in a particular composition is not critical and can be readily determined by a person of ordinary skill in the art. By way of non-limiting example, a typical amount is from 99.9 percent to 15 percent, alternatively from 99.9 percent to 25 percent, or alternatively from 99.9 percent to 55 percent, by weight of the surfactant based on the total weight of the alkoxylate of formula I and the surfactant component.

The composition of the invention may be formulated as a concentrate, which may contain water as an aqueous carrier, or the composition may be formulated as a diluted, ready to use, composition. For the concentrate, the amount of water may, for instance, be from 0 to 50 weight percent, based on the total weight of the composition. For the diluted composition, the amount of water may, for instance, be from 50 to 99.5 weight percent, based on the total weight of the composition.

The cleaning compositions of this invention may include any of the well-known and conventional components used in such compositions. Such components include, for example, but without limitation, pH modifying agents, thickening agents, anti- streaking agents, buffers, builders, chelating or sequestering agents, hydrotopes, anti-microbial agents, colorants, and perfumes. Selection and use of such components is well within the capabilities of the skilled formulator.

As noted above, the alkoxylates of formula I of the invention function as zero VOC solvents for cleaners according to CARB definition. Because of this property, the alkoxylates of formula I may be used as replacements for other VOC contributing organic solvents. Thus, in some embodiments, the invention provides cleaning composition that are zero or low VOC.

The cleaning composition of the invention is useful in industrial or consumer applications including, but not limited to, as a home care consumer aerosol cleaner, a cold water laundry formulation, a hand dish cleaner, a machine dish cleaner, a degreaser formulation, a graffiti cleaner, a hard surface cleaner, and any combination thereof.

Some embodiments of the invention will now be described in detail in the following Examples.

EXAMPLES

Example 1. Synthesis of 2EH-0-P0 ₅ -OH

Propoxylation of 2-ethylhexanol is performed in a jacketed, autoclave reactor. Solid double metal cyanide catalyst (DMC, 0.48 g) is charged with 2-ethylhexanol (1850.90 g). The mixture is heated to 130 °C. Propylene oxide (PO, 4171.90 g) is added to the 2- ethylhexanol-DMC mixture over 8 hours 16 minutes, during which the temperature is kept at 130 °C. The mixture is kept at 130 °C for 14 h before being cooled back to room temperature. Analysis of the reaction mixture determined that the product has a molecular weight of 426 based on a percent hydroxyl analysis, which is consistent with the average molecular weight for 2ΕΗ-0-Ρ0 ₅ -ΟΗ.

Example 2. Vapor Pressure Measurement of Example 1

Vapor pressure of Example 1 material (2ΕΗ-0-Ρ0 ₅ -ΟΗ) at room temperature was determined by measuring its vapor pressure at various temperatures. The data were fitted to the Antoine equation (Reference: http://en.wikipedia.org/wiki/Antoine_equation) to determine Antoine constants A, B, and C. Vapor pressure at 20 °C was then calculated using the following equation:

B

log jD = A

^{5 F} C + T

p = vapor pressure (mmHg); T = temperature (°C); A, B, C are Antoine constants.

Example l's vapor pressure was calculated to be < 0.1 mmHg. Example 1 therefore is not considered a VOC according to CARB, i.e., it is a zero VOC solvent according to the definition from CARB.

Performance Testing

Example 3. Removal of greasy soil containing carbon black on a hard surface.

The efficiency for a formulation to remove greasy soil containing carbon black on a hard surface is evaluated by a scrubbing test. A vinyl tile is soiled by spreading 500 uL of a carbon black soil (57.7% naphtha, 26.1% caprylic/capric triglyceride, 7.7% soybean oil, and 8.5% carbon black) uniformly using a foam brush. The tile is air-dried in a fume hood. The soiled tile is divided into 24 wells by compressing a metal block containing 24 cylindrical holes on the soiled tile. Each formulation is added to three wells (250 uL in each well) in random locations. A scrubber is placed in each well. The setup is shaken on an orbital shaker at 700 rpm for 5 min. After scrubbing, cleaning solutions are removed and the wells are rinsed gently with DI water. The vinyl tile is dried overnight.

An image of the vinyl tile is recorded with a scanner, and analyzed by imaging software ImageJ to determine the grey scale in each well. Since each formulation is tested in three wells, three grey scale values are obtained for each formulation. The average grey scale value is reported. The larger the grey scale value, the whiter the tile and therefore the better a formulation removes carbon black from greasy soil. Table 1 summarizes the grey value of 8 formulations.

Table 1. Composition (wt%) of hard surface cleaner formulations and grey scale value after a scrubbing test

Versene 100 = EDTA = Ethylenediaminetetraacetic acid tetrasodium salt

Surfactant blend A= 33.3 wt% TERGITOL™ 15S15, 33.3 wt% ECOSURF™ EH6, 33.4% ECOSURF™ EH9. ECOSURF™ EH-6, ECOSURF™ EH-9, and TERGITOL™ 15S15 are nonionic, alcohol -alkoxylate surfactants available from Dow.

Surfactant blend B = 25 wt% ECOSURF™ EH6, 25 wt% ECOSURF™ EH9, 50 wt% TERGITOL™ 15S15

HEIDA = 2-hydroxyethyliminodiacetic acid, disodium salt

EH-9 = ECOSURF™ EH9

LAS = linear alkyl benzene sulfonate

It can be concluded from replacing hydrocarbon solvent such as dodecane with example 1 (2ΕΗ-0-Ρ0 ₅ -ΟΗ) significantly improved the ability of a cleaning formulation to remove greasy carbon black soil from a hard surface.

Example 4. Removal of food soil with hand dish detergent formulation

The efficiency of a hand dish detergent formulation to clean plates with food soil is determined by a manual hand dish scrubbing test. Two grams of food soil (freshly prepared from 21% soybean oil, 11% lard, 13% whole egg powder, 11% potato flour, 44% water) is spread on a clean plate with a finger. A set of plates are prepared this way and are stacked. The soil is dried to 2 hours. Warm water (4L, 43 °C) is added to a dish pan. A cellulose sponge is wetted in the warm water and wringed out completely. Add 2 g dish detergent formulation to the warm water by dropping the cleaner into the water in a figure 8 pattern. A plate is dipped into the warm detergent solution for several seconds and removed from the detergent solution. The plate is hand-scrubbed in a circular motion by a sponge for 10- 20 seconds. The plate is rinsed in clean hot water. The plate is visually inspected to determine whether or not the plate is cleaned. The process is repeated with a new soiled plate until the plate remains dirty after scrubbing. Additive (Example 1) is added to Dawn hand dish detergent to determine if this additive improves the food soil removal efficiency of Dawn detergent. Table 2 summarizes the formulation composition and the cleaning results.

Table 2. Composition (wt%) of hand dish detergent formulations containing different solvents

It can be concluded that more plates can be cleaned by adding example 1 to Dawn detergent.

In another comparison study to evaluate food soil removal efficiency, Example 1 is compared with a glycol ether solvent of lower molecular weight (hexyl carbitol). Table 3 summarizes the formulation composition and the cleaning results. The formulations containing low molecular weight glycol ether (hexyl carbitol) cleaned four plates (4i and 4j), whereas formulation containing Example 1 cleaned five plates (4g and 4h).

Table 3. Com osition (wt ) of hand dish deter ent formulations containin different solvents

AL - Ammonyx-LO (an -amine oxide surfactant from Stepan)

CS-270 = Steol CS270 (-a sodium laureth sulfate surfactant from Stepan)

CG-650 = TRITON CG650 (an alkyl polyglucoside surfactant from Dow)

EH6 = ECOSURF EH6 (a nonionic alcohol alkoxylate surfactants from Dow)

Example 5. Removal of Fabric Soils by Laundry Detergent Formulations

In this example, common laundry soils such as crayon, lipstick, and grease on fabric are cleaned with laundry detergent formulations in a tergotometer and the cleaning results are compared with Tide 2X Ultra Original Scent detergent. Pre-soiled fabric (with crayon, lipstick, and grease stain) is purchased from Scientific Services S/D Inc. The color of the fabric is analyzed by Ultra Scan UV spectrometer before the cleaning experiment.

A tergotometer pot is filled with deionized water (1L). Detergent (2 g) is added, followed by a piece of pre-soiled fabric. For each formulation a total of 2 replicates are evaluated with each type of soiled fabric. The tergotometer set up is agitated for 15 minutes at 50 °C. Detergent solution is removed and the fabric is returned to the tergotometer pot for 1 rinse cycle. The rinse cycle involves 1L of water and 15 minutes of agitation at 50 °C. After the rinse cycle is completed, the fabric is put on a drying rack to dry. The color of the dried fabric after the cleaning experiment is analyzed by the same Ultra Scan UV spectrometer and the change in whiteness (dE) is recorded. The larger the value of dE, the whiter the fabric after cleaning, which indicates better cleaning performance.

Table 4 summarizes the recipe of formulations 5a and 5b. Table 5 shows the results. Formulation 5b, which contains more example 1 than formulation 5a, removes crayon and lipstick soil more effectively than Tide 2X Ultra.

Table 4. Composition (wt ) of laundry formulations containing different solvents

Di-PPh = DOWANOF DiPPH (a glycol ether solvent from Dow)

TPM = DOWANOF TPM (a glycol ether solvent from Dow)

15S15 = TERGITOF 15S15 (nonionic surfactant from Dow)

FAS = Finear alkyl benzene sulfonate

EH6= ECOSURF EH6 (nonionic surfactant from Dow)

EH9= ECOSURF EH9(nonionic surfactant from Dow)

Table 5. Cleaning results of laundry formulations