EP0617733B1

EP0617733B1 - Granular laundry detergent and detergent builder

Info

Publication number: EP0617733B1
Application number: EP92925246A
Authority: EP
Inventors: Terry Crutcher; Joe D. Sauer; Kim R. Smith; James E. Borland
Original assignee: Albemarle Corp
Current assignee: Albemarle Corp
Priority date: 1991-12-19
Filing date: 1992-11-17
Publication date: 1997-04-23
Anticipated expiration: 2012-11-17
Also published as: CA2126238A1; JPH07509501A; WO1993012217A1; DE69219358D1; EP0617733A1; DE69219358T2

Abstract

A phosphate-free granular laundry detergent having a cleaning performance comparable to that of a premium phosphate-containing laundry detergent comprises: (A) 1-30 % by weight of a surfactant, (B) 1-50 % by weight of a sodium aluminum silicate detergent builder, (C) 1-20 % by weight of sodium silicate, (D) 0.1-5 % by weight of an anti-redeposition agent, and (E) 10-80 % by weight of inorganic filler, the surfactant consisting of: (1) a mixture of 20-98 % by weight of an ethoxylated fatty alcohol, 1-75 % by weight of an alkali metal or ammonium salt of an alkylbenzene sulfonate in which the alkyl group contains 10-18 carbons, and 1-20 % by weight of an amine oxide corresponding to the formula RR'R''NO in which R is a primary alkyl group containing 8-24 carbons; R' is methyl, ethyl, or 2-hydroxyethyl; and R'' is independently selected from methyl, ethyl, 2-hydroxyethyl, and primary alkyl groups containing 8-24 carbons, or (2) a mixture of 85-98 % by weight of the ethoxylate, 1-12 % by weight of a fatty acid soap, and 1-6 % by weight of the amine oxide.

Description

Field of Invention

This invention relates to phosphate-free granular laundry detergents and more particularly to such detergents having improved cleaning power.

Background

Granular laundry detergents, or laundry powders, typically comprise (A) one or more surfactants, such as alkyl sulfates, alkyl ether sulfates, alkylbenzene sulfonates, ethoxylated alkylphenols, ethoxylated alcohols, or amine oxides, and (B) one or more detergent builders, such as sodium tripolyphosphate, sodium nitrilotriacetate, or a sodium aluminum silicate. The use of a phosphate in these detergents is known to be undesirable from an environmental point of view, but the phosphate-free detergents hitherto obtained by replacing phosphate builders with other builders have suffered a considerable loss in cleaning power because of that replacement.

Summary of Invention

It has been found that the use of certain carefully proportioned mixtures of an ethoxylated fatty alcohol, an anionic surfactant, and an amine oxide corresponding to the formula RR'R"NO in which R is a primary alkyl group containing 8-24 carbons; R' is methyl, ethyl, or 2-hydroxyethyl; and R" is independently selected from methyl, ethyl, 2-hydroxyethyl, and primary alkyl groups containing 8-24 carbons can make it possible to provide a phosphate-free, sodium aluminum silicate (zeolite)-containing granular laundry detergent which has a cleaning performance comparable to that of a phosphate-containing laundry detergent.
It has also been discovered that, when the amine oxide is one in which R' and R" are independently selected from methyl, ethyl, and 2-hydroxyethyl, and it is blended with the zeolite so as to provide 2.3-7.0 mmols of amine oxide per gram of zeolite, it increases the divalent ion sequestration rate of the zeolite; and the use of the blend in the laundry detergent minimizes premature precipitation of the anionic surfactant from solution when the laundry detergent is used.
Thus, the invention resides in:

(A) a phosphate-free laundry detergent which comprises (1)1-30% by weight of a surfactant, (2) 1.50% by weight of a sodium aluminum silicate detergent builder, (3) 1-20% by weight of sodium silicate, (4) 0.1-5% by weight of an anti-redeposition agent, and (5) 10-80% by weight of inorganic filler, the surfactant consisting of (a) a mixture of 20-98% by weight of the aforementioned ethoxylate, 1-75% by weight of an alkali metal or ammonium salt of an alkylbenzene sulfonate in which the alkyl group contains 10-18 carbons, and 1-20% by weight of the aforementioned amine oxide containing one or two long-chain alkyl groups or (b) a mixture of 85-98% by weight of the ethoxylate, 1-12% by weight of a fatty acid soap, and 1-6% by weight of the amine oxide, and
(B) an amine oxide/zeolite mixture suitable for use in the laundry detergent and containing (1) 2.3-7.0 mmols/gram of zeolite of the aforementioned amine oxide containing only one long-chain alkyl group and (2) only 0-30% of water.

Detailed Description

The surfactant which comprises 1-30% by weight of the laundry detergent is preferably employed in an amount such as to constitute 10-20% of the total detergent weight, and its components are preferably proportionated so that the surfactant consists of at least 80% by weight of the ethoxylated fatty alcohol and up to 10% by weight of each of the other components when the anionic surfactant is an alkylbenzene sulfonate and at least 90% by weight of the ethoxylate and up to 5% by weight of each of the other components when the anionic surfactant is a fatty acid soap.
Ethoxylated fatty alcohols which may be used in the practice of the invention are ordinarily compounds corresponding to the formula Z(OCH₂CH₂)_nOH in which Z is an alkyl group containing 4-30 carbons, preferably 10-18 carbons, and n is an integer of 1-50, preferably 2-15. Particularly preferred ethoxylated fatty alcohols are apt to be (1) the ethoxylate of a mixture of C₆ and C₁₀ alcohols in which n is 3, (2) the ethoxylate of a mixture of C₁₂ and C₁₄ alcohols in which n is 3, and (3) the ethoxylate of a mixture of C₁₂ and C₁₄ alcohols in which n is 6. However, other ethoxylates corresponding to the formula, such as those formed from one or more alcohols such as butanol, isobutanol, hexanol, octanol, decanol, dodecanol, tetradecanol, pentadecanol, hexadecanol, octadecanol, eicosanol, docosanol, tetracosanol, and triacontanol, are also utilizable.
The alkylbenzene sulfonate component of the laundry detergent may be any alkali metal or ammonium salt of an alkylbenzene sulfonate in which the alkyl group contains 10-18 carbons, but it is preferably sodium dodecylbenzene sulfonate.
The fatty acid soap may be any of the fatty acid salts, usually sodium salts, known as soaps - usually a salt of a fatty acid containing 12-20 carbons, such as oleic, ricinoleic, and stearic acids, tallow fatty acid mixtures, and coco fatty acid. The C₁₂ coco soaps are preferred however.
As already indicated, the amine oxide component may be one containing one or two long-chain alkyl groups, although - to permit increasing the divalent ion sequestration rate of the zeolite - it is preferred for the amine oxide to contain only one long-chain alkyl group, most preferably such a group containing 10-18 carbons and having a straight chain in at least most of the molecules, generally at least 70%, preferably at least 90% of the molecules. Especially preferred are the amine oxides in which both R' and R" are methyl.
The utilizable amine oxides include, e.g., N-octyldimethylamine oxide, N,N-didecylmethylamine oxide, N-decyl-N-dodecylethylamine oxide, N-dodecyldimethylamine oxide, N-tetradecyldimethylamine oxide, N-tetradecyl-N-ethylmethylamine oxide, N-tetradecyl-N-ethyl-2-hydroxyethylamine oxide, N,N-ditetradecyl-2-hydroxyethylamine oxide, N-hexadecyldimethylamine oxide, N-hexadecyldi-2-hydroxyethylamine oxide, N-octadecyldimethylamine oxide, N,N-dieicosylethylamine oxide, N-docosyl-N-2-hydroxyethylmethylamine oxide, N-tetracosyldimethylamine oxide, and mixtures thereof. N-tetradecyldimethylamine oxide is particularly preferred.
Although the amine oxide used in the practice of the invention may be a conventional amine oxide (i.e., one prepared as a dilute aqueous solution), it is preferable for the amine oxide to be one that has been prepared in solid form, such as the amine oxide dihydrates and dihydrate-containing materials of U.S. Patent 5,071,594 (Borland et al.). Dilute aqueous solutions have to be dried in the production of a laundry powder. Moreover, when the amine oxide is blended with the zeolite so as to increase its divalent ion sequestration rate, it is important for the resulting mixture to contain 0-30% by weight of water so that it will be a powder rather than a paste.
The detergent builder which is employed together with the aforementioned surfactant mixture is a sodium aluminum silicate, and it is used in an amount such as to constitute 1-50%, preferably 20-40%, of the total weight of the laundry detergent. Any suitable zeolite, e.g., zeolite A, X, or Y, may be utilized as the sodium aluminum silicate; but zeolite A is ordinarily preferred.
The remaining essential components of the laundry detergent are (1) sodium silicate, which makes up 1-20%, preferably 5-15%, of the total weight of the detergent, (2) an anti-redeposition agent, such as sodium polyacrylate or sodium carboxymethylcellulose, which constitutes 0.1-5%, preferably 0.1-1%, of that total weight, and (3) one or more inorganic fillers, or processing aids, such as sodium sulfate, carbonate, or bicarbonate, which make up 10-80% of the weight of the detergent. If desired, however, the detergent may also contain optional ingredients, e.g., one or more bleaching agents, such as sodium percarbonate or perborate, and one or more of the fabric softeners, such as quaternary ammonium salts, sometimes used in laundry detergents.
Although the components of the laundry detergent may be combined in any suitable manner, it is frequently preferred to preblend the zeolite and the amine oxide, especially when the amine oxide is contains only one long chain and is to be mixed with the zeolite in such proportions as to increase the divalent ion sequestration rate, i.e., so as to provide 2.3-7, preferably 3.1-5.4, more preferably 3.5-4.7, and most preferably about 3.9 mmols of the amine oxide per gram of the zeolite. Such an increase in sequestration rate is important, since (1) builders generally have to function adequately in the first two minutes of detergent use in order to be most effective and (2) the relatively slow sequestration rate of conventional zeolite builders, especially at the lower wash temperatures (30-40°C) frequently used today, has been a factor in making zeolites much less desirable than phosphates as builders in cleaning compositions containing anionic surfactants.
These amine oxide/zeolite builder systems may be incorporated into the laundry detergents of the invention or other anionic surfactant-containing cleaning compositions in the same manner as conventional detergent builders to produce formulations from which the anionic surfactants are less apt to precipitate prematurely. In general, such cleaning compositions include:

(A) hard surface cleaners, which typically comprise 1-25% by weight of one or more surfactants; 0-25% by weight of one or more bleaching agents, such as sodium percarbonate or perborate; 1-20% by weight of a pH modifier, such as sodium silicate; 10-80% by weight of one or more processing aids, such as sodium sulfate or sodium carbonate; and 1-50% by weight of the builder, and
(B) laundry detergent powders, which typically have the same ingredients as the hard surface cleaners in essentially the same proportions but also contain 0.1-5% by weight of one or more anti-redeposition agents.

The laundry detergents of the invention are advantageous in that they match premium phosphate-containing detergents in performance while being free of (1) the phosphates that are already of environmental concern and (2) any unusual ingredients that would require new environmental or toxicological testing. Moreover, they are effective over a wide range of soils and conditions; impart softening to laundered fabrics even without the inclusion of additional fabric softeners, such as the quaternary ammonium salts mentioned above; and can actually be less costly to make than premium phosphate-containing and phosphate-free laundry detergents that are already commercially available.
The following examples are given to illustrate the invention and are not intended as a limitation thereof. Unless otherwise specified, quantities mentioned in the examples are quantities by weight.

EXAMPLE 1

Part A - Control

Stir a 250 mL solution of water containing 500 ppm of calcium with 0.10g of zeolite A for 20 minutes at 22°C while monitoring the amount of calcium remaining in solution with a calcium ion selective electrode. At the end of the 20-minute period, there is a 100 ppm decrease in the calcium content of the solution, but no significant uptake of calcium by the zeolite A is noted at the critical two-minute point.

Part B - Control

Repeat Part A except for replacing the 0.10g of zeolite A with 0.10g of N-tetradecyldimethylamine oxide (C₁₄AX). The ultimate uptake of calcium is 30 ppm, all of which is taken up during the first two minutes.

Part C- Control

Repeat Part A except for replacing the 0.10g of zeolite A with 0.20g of a 25/75 blend of C₁₄AX and zeolite A (1.3 mmols of amine oxide/gram of zeolite). As in Part A, there is a 100 ppm decrease in the calcium content of the solution at the end of the 20-minute period but no measurable amount of calcium uptake during the first two minutes.

Part D - Control

Repeat Part C except for using a 3/1 blend of C₁₄AX and zeolite A (11.7 mmols of amine oxide/gram of zeolite). The ultimate uptake of calcium is 10 ppm, all of which is taken up during the first two minutes.

Part E

Repeat Part C except for using a 1/1 blend of zeolite A and C₁₄AX (3.9 mmols of amine oxide/gram of zeolite). As in Parts A and C, there is a 100 ppm decrease in the calcium content of the solution at the end of the 20-minute period. However, the majority of the calcium uptake, i.e., 70 ppm, occurs by the critical two-minute point.

EXAMPLE 2

Prepare four laundry detergents from the indicated number of parts of the ingredients shown in Table I to produce Blends A and B (phosphate-free laundry detergents of the invention), Blend C (a phosphate-free control laundry detergent), and Blend D (a phosphate-containing control laundry detergent) - the two control blends being formulated to match premium commercial laundry detergents.

TABLE I

Ingredients	Blends
	A	B	C*	D*
N-tetradecyldimethylamine oxide	1	1	--	--
Sodium dodecylbenzene sulfonate	1	--	13	10
C₁₂ coco soap	--	1	--	--
6-EO ethoxylate of a mixture of C₁₂ and C₁₄ alcohols	18	18	--	--
Soda ash	41.6	41.6	22	24
Sodium sulfate	--	--	25	25
Sodium silicate	8	8	2	5
Sodium carboxymethylcellulose	--	--	1	1
Sodium polyacrylate	0.4	0.4	--	--
Sodium tripolyphosphate	--	--	--	30
Zeolite A	30	30	30	--
Tridecyl sulfate	--	--	7	5

* comparative blends

EXAMPLE 3

Part A

Test the cleaning performance of laundry detergents A, C, and D of Example 2 by (1) placing six standard dust-sebum soiled cotton/polyester swatches in a vessel containing one liter of 200 ppm hard water (Ca⁺⁺/Mg⁺⁺ratio of 3/2), (2) adding 1.5g of the detergent to be tested, (3) agitating the contents of the vessel for ten minutes at 100 rpm, (3) rinsing the swatches with the hard water for five minutes at the same temperature used for the washing, (4) drying the rinsed swatches on a flat bed press for ten minutes, (5) measuring the reflectance of each of the swatches in a tergotometer, (6) averaging the results, and (7) calculating the difference between the average reflectance and the reflectance of a zero control as the detergency (L). In one test, use a temperature 38°C, the temperature now most commonly used for laundering; and use temperatures of 22°C and 55°C in two other tests. The results of the tests are shown in Table II.

Part B

Repeat Part A except for using EMPA 101 (a mixture of motor oil and charcoal) soiled swatches instead of the dust-sebum soiled swatches. The results of the tests are shown in Table II.

Part C

Repeat Part A except for using clay soiled swatches instead of the dust-sebum soiled swatches. The results of the tests are shown in Table II.

TABLE II

Increase in Reflectance
Soil Type	Test Temperature	Blend A	Blend C	Blend D
Dust-sebum	38°C	24.1	18.8	24.0
	55°C	24.0	18.5	21.2
	22°C	22.5	16.0	23.5
EMPA 101	38°C	21.2	22.2	19.8
	55°C	20.5	22.0	21.0
	22°C	15.5	14.8	14.8
Clay	38°C	14.7	14.1	15.0
	55°C	15.0	13.8	16.0
	22°C	14.0	13.1	14.1

The test results obtained with Blend B are similar to those obtained with Blend A, which, as demonstrated above, compares very favorably with premium commercial laundry detergents in cleaning performance when used in water having a hardness of 200 ppm Ca and in an amount comparable to one cup of detergent in a normal washing machine. The following examples show that a favorable comparison in its performance is also found when the water used for the test has different degrees of hardness or when different amounts of detergent are utilized.

EXAMPLE 4

Repeat the Example 3 test at 38°C on dust-sebum soiled swatches except for varying the water hardness as shown in Table III, which also shows the increases in reflectance determined by the tests.

TABLE III

Increase in Reflectance
ppm Ca in Water	Blend A	Blend C	Blend D
0	27.0	25.9	27.9
50	25.9	26.1	26.9
100	25.9	24.0	26.9
150	25.0	19.5	25.9
200	24.1	18.8	24.0
250	21.9	15.3	18.5
300	20.0	15.1	18.5
350	17.9	15.0	18.1
400	18.1	15.5	17.9

EXAMPLE 5

Repeat the Example 3 test at 38°C on dust-sebum soiled swatches except for (1) using polyester/cotton swatches provided by a different manufacturer and having a higher loading of soil and (2) varying the amount of detergent employed as shown in Table IV, which also shows the increases in reflectance determined by the tests.

TABLE IV

Increase in Reflectance
g Detergent per L Water	Blend A	Blend C	Blend D
0.5	11.0	5.9	6.5
1.0	15.0	13.0	11.5
1.5	19.9	15.0	20.0
2.0	20.5	16.0	22.0
2.5	22.0	21.0	22.0
3.0	22.5	21.5	22.6
3.5	23.0	21.5	23.0

Claims

A phosphate-free granular laundry detergent comprising (A) 1-30% by weight of an ethoxylated fatty alcohol/anionic surfactant/amine oxide surfactant mixture wherein the amine oxide corresponds to the formula RR'R"NO in which R is a primary alkyl group containing 8-24 carbons; R' is methyl, ethyl, or 2-hydroxyethyl; and R" is independently selected from methyl, ethyl, 2-hydroxyethyl, and primary alkyl groups containing 8-24 carbons, (B) 1-50% by weight of a sodium aluminum silicate detergent builder, (C) 1-20% by weight of sodium silicate, (D) 0.1-5% by weight of an anti-redeposition agent, and (E) 10-80% by weight of inorganic filler, the surfactant mixture consisting of (1) a mixture of 20-98% by weight of the ethoxylate, 1-75% by weight of an alkali metal or ammonium salt of an alkylbenzene sulfonate in which the alkyl group contains 10-18 carbons, and 1-20% by weight of the amine oxide or (2) a mixture of 85-98% by weight of the ethoxylate, 1-12% by weight of a fatty acid soap, and 1-6% by weight of the amine oxide.
The laundry detergent of claim 1 comprising 10-20% by weight of the surfactant, 20-40% by weight of the builder, 5-15% by weight of the sodium silicate, and 0.1-1% by weight of the anti-redeposition agent.
The laundry detergent of claim 2 wherein (A) the surfactant consists of a mixture of at least 80% by weight of an ethoxylated fatty alcohol corresponding to the formula Z(OCH₂CH₂)_nOH in which Z is an alkyl group containing 10-18 carbons and n is an integer of 2-15, up to 10% by weight of sodium dodecylbenzene sulfonate, and up to 10% by weight of an amine oxide corresponding to the formula RR'R"NO in which R is a primary alkyl group containing 8-24 carbons and R' and R" are independently selected from methyl, ethyl, and 2-hydroxyethyl, (B) the detergent builder is zeolite A, (C) the anti-redeposition agent is selected from sodium polyacrylate, sodium carboxymethylcellulose, and mixtures thereof, and (D) the inorganic filler is one or more compounds selected from sodium sulfate, sodium carbonate, and sodium bicarbonate.
The laundry detergent of claim 3 wherein (A) the surfactant consists of a mixture of 90% by weight of the ethoxylate of a mixture of C₁₂ and C₁₄ alcohols in which n is 6, 5% by weight of sodium dodecylbenzene sulfonate, and 5% by weight of N-tetradecyldimethylamine oxide, (B) the anti-redeposition agent is sodium polyacrylate, and (C) the inorganic filler is sodium carbonate.
The laundry detergent of claim 4 consisting of 20% by weight of the surfactant mixture, 30% by weight of zeolite A, 8% by weight of sodium silicate, 0.4% by weight of sodium polyacrylate, and 41.6% by weight of sodium carbonate.
The laundry detergent of claim 2 wherein (A) the surfactant consists of a mixture of at least 90% by weight of an ethoxylated fatty alcohol corresponding to the formula Z(OCH₂CH₂)_nOH in which Z is an alkyl group containing 10-18 carbons and n is an integer of 2-15, up to 5% by weight of a C₁₂ coco soap, and up to 5% by weight of an amine oxide corresponding to the formula RR'R"NO in which R is a primary alkyl group containing 8-24 carbons and R' and R" are independently selected from methyl, ethyl, and 2-hydroxyethyl, (B) the detergent builder is zeolite A, (C) the anti-redeposition agent is selected from sodium polyacrylate, sodium carboxymethylcellulose, and mixtures thereof, and (D) the inorganic filler is one or more compounds selected from sodium sulfate, sodium carbonate, and sodium bicarbonate.
The laundry detergent of claim 6 wherein (A) the surfactant consists of a mixture of 90% by weight of the ethoxylate of a mixture of C₁₂ and C₁₄ alcohols in which n is 6,5% by weight of the soap, and 5% by weight of N-tetradecyldimethylamine oxide, (B) the anti-redeposition agent is sodium polyacrylate, and (C) the inorganic filler is sodium carbonate.
The laundry detergent of claim 7 consisting of 20% by weight of the surfactant mixture, 30% by weight of zeolite A, 8% by weight of sodium silicate, 0.4% by weight of sodium polyacrylate, and 41.6% by weight of sodium carbonate.
A mixture suitable for use as a detergent builder and consisting of (A) a zeolite, (B) 2.3-7.0 mmols per gram of zeolite of an amine oxide corresponding to the formula RR'R"NO in which R is a primary alkyl group containing 6-24 carbons and R' and R" are independently selected from the group consisting of methyl, ethyl, and 2-hydroxyethyl, and (C) 0-30% of water, based on the weight of the mixture.
The mixture of claim 9 wherein R is a primary alkyl group containing 10-18 carbons, R' and R" are methyl, and the amount of amine oxide is 3.1-5.4 mmols per gram of zeolite.
The mixture of claim 10 wherein the amount of amine oxide is 3.5-4.7 mmols per gram of zeolite.
The mixture of claim 11 wherein the amine oxide is N-tetradecyldimethylamine oxide and the zeolite is zeolite A.