Patent Application
20080274936
This invention relates to laundry detergent compositions having a high water soluble alkaline carbonate (soda ash) builder content.
Laundry detergent compositions comprising a water-soluble alkaline carbonate are well-known in the art. For example, it is conventional to use such a carbonate as a builder in detergent compositions which supplement and enhance the cleaning effect of an active surfactant present in the composition. Such builders improve the cleaning power of the detergent composition, for instance, by the sequestration or precipitation of hardness causing metal ions such as calcium, peptization of soil agglomerates, reduction of the critical micelle concentration, and neutralization of acid soil, as well as by enhancing various properties of the active detergent, such as its stabilization of solid soil suspensions, solubilization of water-insoluble materials, emulsification of soil particles, and foaming and sudsing characteristics. Other mechanisms by which builders improve the cleaning power of detergent compositions are probably present but are less well understood. Builders are important not only for their effect in improving the cleaning ability of active surfactants in detergent compositions, but also because they allow for a reduction in the amount of the surfactant used in the composition, the surfactant being generally much more costly than the builder.
Sodium carbonate (Na2CO3) and/or potassium carbonate (K2CO3) are the most common carbonates included in laundry detergents to impart increased alkalinity to wash loads, thereby improving detergency against many types of soils. In particular, soils having acidic components e.g. sebum and other fatty acid soils, respond especially well to increased alkalinity.
While laundry detergents containing a relatively large amount of carbonate builder are generally quite satisfactory in their cleaning ability, the use of such carbonate builders often results in the problem of calcium carbonate precipitation, which may give rise to fabric encrustation due to the deposition of the calcium carbonate on the fiber surfaces of fabrics which in turn causes fabric to have a stiff hand and gives colored fabrics a faded appearance. Thus, any change in available carbonate built laundry detergent compositions which reduces their tendency to cause fabric encrustation is highly desirable.
In many applications, it is desirable to include Na2CO3 and K2CO3 in detergent formulations at levels greater than 20%. This is readily achieved in the case of a powdered detergent. However, incorporating such large amounts into an aqueous liquid is much more difficult. In liquid laundry detergent compositions, the incorporation of a large amount of detergent builder poses a significant formulation challenge since the presence of a major quantity of detergent builder inevitably causes the detergent composition to phase separate. Liquid detergent formulations that contain a detergent builder ingredient require careful control of the surfactant to builder ratio so as to prevent salting-out of the surfactant phase. Liquid laundry detergent compositions are also susceptible to instability under extended freeze/thaw and high/low temperature conditions.
Additionally, sodium carbonate forms an extensive array of low water soluble hydrates at low temperatures and high, i.e., >15 wt. % levels of the sodium carbonate builder. For example, a system with 20% carbonate builder will form a decahydrate phase below 23° C. At 30% sodium carbonate, the decahydrate will form below 31° C. Therefore, even at room temperature, systems containing greater than 20% carbonate builder are inherently unstable and readily form decahydrate phases. Once the decahydrate forms, redissolution can take an inordinate amount of time.
Accordingly, there is still a desire and a need to provide a stable liquid laundry detergent which has a high ash content.
In accordance with the present invention, a stable aqueous-based liquid laundry detergent is provided with an ash content of greater than 15 wt. % by incorporating a hygroscopic agent therein in sufficient amounts to prevent excessive insoluble hydrate formation. One or more surfactants including anionic, non-ionic and amphoteric or zwitterionic surfactants can be added. Stability of the liquid composition is further provided by adjusting the ratio of anionic surfactant to zwitterionic surfactant contained in the composition.
The water-soluble alkaline carbonate builder in the detergent composition of this invention may be, for example, an alkali metal carbonate, bicarbonate or sesquicarbonate, preferably sodium or potassium carbonate, bicarbonate or sesquicarbonate, and most preferably sodium carbonate or mixtures of sodium carbonate and potassium carbonate. A combination of more than one of such compounds may be used, e.g., sodium carbonate and sodium bicarbonate. The total alkaline carbonate may be present in an amount, for example, of greater than 15 wt. %, up to about 40 wt. %. Preferably about 20 to about 30 wt. % of sodium carbonate or mixtures of sodium carbonate and potassium carbonate are used.
To reduce the formation of water insoluble hydrates of the carbonate builder, the composition of the present invention includes one or more hygroscopic agents. Useful hygroscopic agents include polyols such as glycerin as well as urea. Other compounds known to bind water are useful hygroscopic agents for incorporation into the composition. In general, 5-25 percent by weight of the composition will comprise the hygroscopic agent.
The active surfactant component of the detergent composition of this invention may be, for example, one or more of many suitable synthetic detergent active compounds which are commercially available and described in the literature, e.g., in “Surface Active Agents and Detergents,” Volumes 1 and 2 by Schwartz, Perry and Berch. Several detergents and active surfactants are also described in, for example, U.S. Pat. Nos. 3,957,695; 3,865,754; 3,932,316 and 4,009,114. In general, the composition may include a synthetic anionic, nonionic, amphoteric or zwitterionic detergent active compound, or mixtures of two or more of such compounds.
More preferably, the laundry detergent compositions of this invention contain at least one anionic, and, most preferably, a mixture of at least one anionic and an amphoteric or zwitterionic surfactant.
The contemplated water soluble anionic detergent surfactants are the alkali metal (such as sodium and potassium) salts of the higher linear alkyl benzene sulfonates and the alkali metal salts of sulfated ethoxylated and unethoxylated fatty alcohols, and ethoxylated alkyl phenols. The particular salt will be suitably selected depending upon the particular formulation and the proportions therein.
The sodium alkybenzenesulfonate surfactant (LAS), if used in the composition of the present invention, preferably has a straight chain alkyl radical of average length of about 11 to 13 carbon atoms.
Specific sulfated surfactants which can be used in the compositions of the present invention include sulfated ethoxylated and unethoxylated fatty alcohols, preferably linear primary or secondary monohydric alcohols with C10-C18, preferably C12-C16, and more preferably, C11-C15, alkyl groups and, if ethoxylated, on average about 1-15, preferably 2-12, and most preferably 2-7 moles of ethylene oxide (EO) per mole of alcohol, and sulfated ethoxylated alkylphenols with C8-C16 alkyl groups, preferably C8-C9 groups, and on average from 4-12 moles of EO per mole of alkyl phenol.
The preferred class of anionic surfactants are the sulfated ethoxylated linear alcohols, such as the C12-C16 alcohols ethoxylated with an average of from about 1 to about 12 moles of ethylene oxide per mole of alcohol.
Specific non-ionic surfactants which can be used in the composition of the present invention include ethoxylated fatty alcohols, preferably linear primary or secondary monohydric alcohols with C10-C18 and preferably C12-C16, alkyl groups and on average about 1-15, preferably 1-12 moles of ethylene oxide (EO) per mole of alcohol, and ethoxylated alkylphenols with C8-C16 alkyl groups, preferably C8-C9 alkyl groups, and on average about 4-12 moles of EO per mole of alkyl phenol.
The preferred class of nonionic surfactants are the ethoxylated linear alcohols, such as the C12-C16 alcohols ethoxylated with an average of from about 1 to about 12 moles of ethylene oxide per mole of alcohol.
Mixtures of the foregoing synthetic detergent types of surfactants, e.g., of anionic and nonionic, or of different specific anionic or nonionic surfactants, may be used to modify the detergency, sudsing characteristics, and other properties of the composition. For example, a mixture of different fatty alcohols of 12 to 16 carbon atoms may be ethoxylated, directly sulfated, or sulfated after ethoxylation, a fatty alcohol may be partially ethoxylated and sulfated, or an ethoxylated fatty acid may be partially sulfated to yield a mixture of different anionic and nonionic surfactants or different specific anionic or nonionic surfactants.
Further surfactants which can be used in the laundry detergent formulations according to the invention are amphoteric or zwitterionic surfactants, e.g. alkylbetaines, alkylamidobetaines, alkyliminopropionates, aminoglycinates or amphoteric imidazolineum carboxylates, sulfobetaines, sultaines and amine oxide compounds.
Preferred amphoteric surfactants of this formula are monocarboxylates and dicarboxylates. Examples thereof are cocoamphocarboxypropionate, cocoamidocarboxypropionic acid, cocoamphocarboxyglycinate (also referred to as cocoamphodiacetate) and cocoamphoacetate.
Further preferred amphoteric surfactants are alkyldimethylbetaines and alkyldipolyethoxybetaines with an alkyl radical having about 8 to about 22 carbon atoms, which may be linear or branched, preferably having 8 to 18 carbon atoms and particularly preferably having about 12 to about 18 carbon atoms. These compounds are marketed, for example, by Clariant GmbH under the trade name Genagen LAB.
The total active surfactant in the composition may be in the range, for example, of about 3 to 10 wt. %, preferably about 4 to 6 wt. % based on the weight of the composition. If, as preferred, the active surfactant contains of a combination of anionic and amphoteric surfactants, then the weight ratio of anionic surfactant to amphoteric surfactant should be in the range of about 1/30 to 8/1. A more preferred range would be from about 2/3 to about 3/1.
Other agents useful to stabilize the composition and prevent phase separation include thickening agents, gelling agents and dispersing agents. Examples include silica, polyacrylates such as Carbopols, alkyloxylated polycarboxylates, alkoyxylated diamines, e.g. Tetronics from BASF, and alkylpolyglucosides, etc. In general, the stabilizing agents will comprise from about 0.5 to 10 wt. % of the composition.
The balance of the detergent composition will comprise water, generally from about 15 to 75 wt. % of the composition. More preferably, the composition will contain at least 45 wt. % up to 75 wt. % water.
The following samples shown in Table 1 were made.
1ethoxylated polycarboxylate- BASF
The samples were prepared and allowed to sit for 24 to 48 hours. Following formulation, a portion of each was additionally frozen and thawed later at 25° C. to observe freeze-thaw recoverability. The results are summarized in Table 2.
Initially it was found that between 5 and 10 wt. % glycerin was required to produce liquid samples. It was further observed that compositions 7 and 11 recovered from the freeze-thaw cycle with some degree of flowability, however, the rate of flow was very slow. It was thought that the level of Carbopol (at 0.4%) may have been too high. Therefore, a series of samples based on samples 3, 4, 7, 8, 11, and 12 above, only with 0.2% Carbopol 676 instead, were prepared. Observations of these samples are recorded below in Table 3
The decrease in Carbopol level therefore improved the freeze-thaw recoverability of sample 11, but may have decreased the degree of structure for 3, 4, and 7.
Systems were also formulated containing urea. Compositions are shown in Table 4.
Both systems were pourable 24 hours later and recovered from 1 freeze-thaw cycle.
Additional samples as shown in Table 5 were formulated.
2Pluronic EO-PO surfactant- BASF
All formulas were shear-deformable gel-like slurries.
Compositions prepared substituting Pluronic L101 for P103 are shown in Table 6.
All formulas were shear-deformable gel-like slurries.
Compositions containing a mixture of alkali metal carbonates were prepared as shown in Table 7.
It has been found that at least two processing factors are useful to the stability of the system. A series of samples similar to composition 7-1 (only that Na2CO3 was added first) were prepared at different temperatures. Appearances of each are noted in Table 8.
A second useful processing factor was found to be the relative orders of K2CO3 and Na2CO3. It was found that samples based on Example 7-1, where K2CO3 was added first, did not exhibit creaming like similar samples made with the addition of Na2CO3 first. Thus, adding K2CO3 first promoted increased stability in these systems.
The following compositions encompassed varying ratios of Alkyl poly glucoside (APG) and Pluronic L101. Values are in weight % and presented on an as is basis in Table 9.
Samples were prepared at quantities of 300 g in a 600 mL beaker. Mixing was done with an overhead mixer, using a 1.5″ radial flow impeller (for example, Lightnin R-100).
All formulas were uniform, flowable dispersions.
Example 9-3, containing 4.8% total surfactant (actives basis), 25% Na2CO3, and 5% K2CO3, was evaluated for detergency against a commercial laundry detergent formula containing 6.9% total surfactant and 3.3% Na2CO3. Evaluations were performed in a Terg-o-Tometer (Instrument Marketing Services, Inc., Fairfield, N.J.). The device consists of six 1 L buckets with accompanying agitators in order to simulate a washing cycle.
Six soils were chosen for evaluation:
Swatches of each were cut to 2 and ¼ inches square peak to valley with a pinked (zig-zag) cut.
Detergents were added to the Terg buckets at a level of 1.3 g. An appropriate level of water was then added in order to make a total of 990 mL. The water had previously been pre-heated to about 88° F. (the target wash temperature). The solutions in the buckets were then allowed to equilibrate with the terg bath to a temperature of 88±1° F. The terg timer was then set at 11 minutes. The terg was started, and 10 mL of 10,000 ppm (calculated as equivalent level of CaCO3) hard water was added to each bucket. The hardness of each bucket was therefore 100 ppm. With approximately 10 minutes remaining in the wash cycle, 2 swatches of each soil were added to each terg bucket (for a total of 14 swatches per bucket).
At the conclusion of the wash cycle, the swatches were removed from each bucket, squeezed by hand, and placed on a screen. The buckets were then rinsed. To each bucket was then added 990 ml of fresh deionized water along with 10 mL of 10,000 ppm water. Solutions in each bucket were mixed as before. The temperature in each bucket was then allowed to equilibrate at 88±1° F. The terg timer was set to 5 minutes, started, and swatches were added to each bucket. Following this rinse process, the swatches were removed, squeezed by hand, and placed on sieves.
To dry the swatches, a cap was placed on top of the sieve holding the swatches. A heat gun was then used to blow hot air up beneath and through the sieve. Drying of the swatches typically took a couple of minutes.
Runs were performed in duplicate with samples assignments randomized between the buckets for each run.
Soil removal was evaluated by comparing color assessments on swatches before washing and after washing. Color assessments in the CIE L*a*b* color space were performed on unwashed and washed swatches via a BYK Gardner Color-view spectrophotometer.
Summaries of % SR for each detergent are shown in Table 10. Values represent the average of four values. Standard deviations (SD) are also shown. Each of the values were assessed for significance versus the control using a double-sided t-test, with the assumption that the variability between the assessments was unknown, but about equal. Significance was assessed at a level of α=0.05. In Table 10 below, values of % SR from the 9-3 formula not determined to be significantly different from the control are noted as “parity,” while % SR values significantly greater than those of the control are noted as “significantly greater.”
The experimental formula, with a lower total surfactant level than that of the control, performed at a level equal to or significantly greater than that of the control.
The following compositions in Table 11 were made with Pluronic L121 (MW=4400, HLB=1). The compositions differ in the levels of Na2CO3 and K2CO3. All values are in weight % on an as is basis:
Both compositions were uniform, flowable dispersions.
The 11-1 and 11-2 formulas were assessed for detergency as described above. Results are shown in Tables 12 and 13.
Both formulas (containing 4.96% total surfactant) performed at parity or significantly better than the control having 6.9% surfactant.
The experimental formula 9-1 was tested at dose levels of 2.37 and 1.56 oz., and compared with a standard 3.125 oz. dose of a typical commercial laundry detergent. The effective surfactant levels at each dose are compared in Table 14.
Therefore, the levels of surfactant in the experimental detergent doses were less than that in the standard detergent.
The following swatches were evaluated:
Four total replicates of each swatch were run by fastening one swatch of each type to a pillowcase (for a total of four pillowcases). Two pillowcases were washed in one washer while the remaining two pillowcases were washed in another washer of the same make and model. The water hardness was carefully controlled at 100 ppm and the temperature was kept constant at 88° F.
Degrees of soil removal were evaluated as noted in the previous terg-o-tometer results. Results are summarized below. In tests of statistical significance, % SR (% Soil or % Stain Removal) results significantly higher than the control are denoted with (+), less than the control as (−), and equal as (=):
At the 2.37 oz. dose, overall stain removal was about the same as that of the control, while overall soil removal was higher. At the 1.56 oz. dose, performance was at about parity with the control. Among the different stain and soil types, some examples of higher and lower comparative performance levels were seen.
This application claims priority to Provisional Application 60/914,599, filed Apr. 27, 2007.
| Number | Date | Country | |
|---|---|---|---|
| 60914599 | Apr 2007 | US |
