Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – Liquid composition
Reexamination Certificate
2001-09-07
2002-11-19
Ogden, Necholus (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
Liquid composition
C510S424000, C510S426000, C510S428000, C510S536000
Reexamination Certificate
active
06482792
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a process for producing an aqueous liquid laundry detergent composition of desired viscosity and containing nonionic and anionic surfactants.
2. Description of the Related Art Including Information Disclosed Under 37CFR 1.97 and 1.98
Laundry detergent compositions are sold as either solid, i.e., powder or granular compositions, or liquid compositions. The advantages of liquid over solid compositions are that the caking tending to occur with solid compositions is avoided, the liquid composition is more easily dispersed in wash water, and a liquid is more easily measured and added to the washing machine without spillage than is a solid composition. In addition, larger percentages of nonionic surfactants can be incorporated in liquid detergents than in powdered detergents, resulting in greater effectiveness of liquid detergents in removing oily and greasy soils.
A class of liquid laundry detergent compositions comprising an aqueous medium in which is dissolved a sodium carbonate builder, a surfactant blend comprising two ethoxylated long chain alcohol nonionic surfactants, and two sulfated ethoxylated long chain alcohol anionic surfactants, one nonionic and anionic surfactant containing a larger average number of ethoxy groups per molecule than the other nonionic and anionic surfactant, has been found to have superior freeze/thaw and high/low temperature stability as well as excellent detergency, i.e., cleaning ability. However, to achieve a viscosity of this type of liquid detergent within certain desirable limits, it is often necessary to incorporate in the composition additional components such as a hydrotrope, e.g., alcohol or sodium xylene sulfonate, or a high molecular weight polymer viscosity control agent, which materials may detract from the otherwise desirable properties of the composition. Thus, any method for achieving a desired viscosity while eliminating or reducing the need for the use in the composition of a hydrotrope and/or polymeric viscosity control agent is very desirable.
U.S. Pat. No. 4,464,292, issued Aug. 7, 1984 to Lengyel, discloses mixtures of an ethoxylated long chain alcohol nonionic surfactant and an ethoxylated long chain alcohol sulfate anionic surfactant for use in laundry detergents. Also disclosed is the preparation of such mixtures by partially sulfating the nonionic surfactant with concentrated sulfuric acid.
U.S. Pat. No. 5,004,557, issued Apr. 2, 1991 to Nagarajan et al., teaches aqueous liquid laundry detergent compositions comprising a surfactant, a water-soluble sequester builder, and 0.1 to 2% of a homopolymer or copolymer of acrylic acid having a molecular weight in excess of 100,000 as an anti-redeposition and viscosity control agent. The surfactant may be anionic such as an alkylbenzenesulfonate, nonionic such as a condensation product of ethylene oxide with a C
8
-C
18
primary or secondary aliphatic alcohol, amphoteric such as an N-alkylamino acid, or a combination of such surfactants.
U.S. Pat. No. 5,308,530, issued May 3, 1994 to Aronson et al., discloses a liquid detergent composition comprising a surfactant which may be anionic, nonionic, cationic, zwitterionic or ampholytic, or any combination thereof; a calcium-stabilized enzyme; and as a builder or anti-redeposition agent, a copolymer of an unsaturated carboxylic acid and a hydrophobic monomer prepared by solution polymerization.
Pending U.S. patent application Ser. No. 08/851,034, filed May 5, 1997, discloses and claims liquid laundry detergent compositions comprising a sodium carbonate detergent builder; and a surfactant blend of two anionic surfactants, one of which has the formula R—O—(CH
2
CH
2
O)
3
SO
3
M and the other the formula R—O—(CH
2
CH
2
O)
7
SO
3
M, where R is a C
10
-C
16
alkyl group and M is an alkali metal or ammonium cation; and two nonionic surfactants, one of which has the formula R—O—(CH
2
CH
2
O)
3
—H and the other the formula R—O(CH
2
CH
2
O)
7
—H where R is a C
10
-C
16
alkyl group.
Pending U.S. application Ser. No. 08/906,440, filed Aug. 5, 1997, discloses and claims compositions similar to those of Ser. No. 08/851,034 described in the previous paragraph except that the compositions also contain an amphoteric surfactant.
BRIEF SUMMARY OF THE INVENTION
In accordance with this invention, a liquid laundry detergent composition of desired viscosity is produced by a process comprising dissolving in an aqueous medium a water-soluble builder and a surfactant blend comprising two nonionic surfactants and two anionic surfactants, such surfactant blend being prepared by partially sulfating and subsequently neutralizing a mixture of two ethoxylated long chain alcohol nonionic surfactants containing different average numbers of ethoxy groups per molecule, while employing certain values of the weight ratio or “split” of the two nonionic surfactants, and the percent conversion of the nonionic surfactants to sulfated anionic surfactants. These values, which result in a viscosity of the finished detergent formulation within a desired range, are determined by reference to and consistent with preestablished correlations of said ratio and percent conversion with the viscosity of a liquid detergent composition comprising an aqueous solution of the neutralized surfactant blend, indicating that when the percent conversion is increased from lower to higher values at a constant ratio of the two nonionic surfactants, the viscosity increases with the percent conversion, and that when said ratio is increased from lower to higher values at a constant percent conversion, the viscosity rises and reaches a maximum at an intermediate ratio and then falls as the ratio is increased further.
It has been found that when appropriate values of the weight ratio or split of the two nonionic surfactants, and the percent conversion of nonionic surfactants to the anionic sulfates, are employed to obtain a viscosity as close as possible to a desired range consistent with the preestablished correlations discussed previously, the use of such viscosity controlling agents as hydrotropes and/or polymeric carboxylates can be eliminated or reduced.
DETAILED DESCRIPTION OF THE INVENTION
The water-soluble detergent builders contemplated in the liquid detergent compositions of the present invention are, for example, the ammonium and alkali metal carbonates, bicarbonates, sesquicarbonates, orthophosphates, tripolyphosphates, pyrophosphates, hexametaphosphates, borates, silicates, citrates, and mixtures thereof. A preferred group of builders are the sodium and potassium carbonates, bicarbonates, sesquicarbonates, and mixtures thereof and particularly preferred is sodium carbonate (soda ash), as the sole builder or in combination with a minor amount of sodium bicarbonate. The builder may be present in the detergent composition in an amount, for example, of about 0.5 to about 12 wt. %, preferably about 0.5 to about 5 wt. %, based on the weight of the final detergent composition, such amount being independent of the amount of any compound suitable as a builder, e.g. sodium carbonate, used to neutralize the sulfated anionic surfactant component.
As stated, the two nonionic surfactants which are partially sulfated to obtain the surfactant blend of the detergent composition of this invention contain different average numbers of ethoxy groups per molecule. The nonionic surfactant containing the smaller number of ethoxy groups (first nonionic surfactant) is an ethoxylated long chain, preferably straight chain, primary or secondary single alcohol or mixture of alcohols, such alcohols containing about 10 to about 16 carbon atoms, preferably about 12 to about 14 carbon atoms, and an average number of about 1 to about 5 ethoxy groups, preferably about 3 ethoxy groups. The first nonionic surfactant thus has the formula
R—O(CH
2
CH
2
O)
x
—H
where R is one or more primary or secondary alkyl groups, preferably straight chain, each having about 10 to about 16 carbon atoms, preferably about 12 to about 14 carbon atoms, and x is an average
Church & Dwight & Co., Inc.
Ogden Necholus
Shear Stephen
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