CA2030098A1

CA2030098A1 - Chlorine-free liquid automatic dishwashing compositions

Info

Publication number: CA2030098A1
Application number: CA 2030098
Authority: CA
Inventors: Le X. Huynh
Original assignee: Procter and Gamble Co
Current assignee: Procter and Gamble Co
Priority date: 1989-11-21
Filing date: 1990-11-15
Publication date: 1991-05-22
Also published as: EP0429124A1; JPH03210399A

Abstract

ABSTRACT

Liquid automatic dishwashing compositions are provided, which are free of chlorine bleach, contain a solid water-soluble peroxygen compound suspended in a liquid phase containing water and at least one water-miscible solvent and 5% to 30% of a silicate which creates a suspending structure for the solid bleach compound.

Preferred compositions are built with a non-phosphate builder.

Description

~? ~ 3 Chlorine-free liquid automatic dishwashing compositions Le Xuan HUYNH

Technical Field The present invention xelates to liquid automatic dishwashing compositions, which are free of chlorine bleach, and contain a solid water-soluble peroxygen bleach, suspended in a liquid phase;

Background Liquid automatic dishwashing products are well-known; such products usually contain chlorine bleaches.

There is a need for liquid automatic dishwashing products which are Eree of chlorine bleach, for environmental reasons and in view of the strong and unpleasant odor of chlorine.

In EP-A-293 040, published November 30, 1988 and Canadian Patent No. 1,307,714 have been disclosed liquid detergent compositions containing a water-soluble peroxygen bleach, such as perborate tetrahydrate, suspended in a liquid phase consisting of water and a water-miscible organic solvent.

The compositions disclosed in said documents are intended to be used ~or the washing of textiles and in fact, they have an alkalinity below 2 grams NaOH/100 ml of composition.

It is well-known that dishwashing products must have a higher alkalinity, in order to function effectively. It has now been surprisingly found that silicate can be used in liquid automatic dishwashing products, not only to provide at least partly the desired alkalinity, but also to create a suspending structure for the solid water-soluble peroxygen bleach, thus providing a remarkable physical stability to the present compositions, in addition to the chemical stability provided by the liquid phase disclosed in EP-A 293 040 and CP 1,307,714.

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Silicates have been widely described as alkalinity-building ingredients of aqueous thixotropic liquid compositions used for automatic dishwashing purposes. Representative of this art is EP 315 024.

Canadian Patents 1,197,160 and 1,227,719, EP-A-203 660, published December 3, 1~86 and EP-A-295 021, published December 14, 1988 describe liquid detergent compositions containing suspended builder particles where one or more "salting-out"
electrolytes, or "surfactant desolubilizing"
electrolytes are used, to build structured phases with the surfactant materials; such electrolytes include, among many other substances, silicates.

Other patent documents disclosing the use of silicates in cleaning/detergent compositions of the suspending type include GB-A-2031455, published April 23, 1980 and Canadian Patent 950,790 wherein the solid materials to be suspended include abrasives and water-insoluble phosphate builder salts, but do not encompass peroxygen bleach particles; actually, Canadian Patent 1,240,228 which mentions perborate as a possible bleaching ingredient in liquid compositions of the ; suspending type specifically advocates that the compositions must be free of silicate, and instead must contain a carboxylic antigelling agent.

It is provided herewith liquid dishwashing compositions which are chemically and physicall~
stable, environmentally friendly, performing at least equally as state of the art compositions and furthermore being perfectly pourable and exhibiting shear-thinning and thixotropic properties.

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The compositions of the inventioll are preferably built, with a non-phosphate builder, this latter feature completing the "environmentally friendly" character of the present composition.

Chlorine-free liquid automatic dishwashing compositions having an alkalinity of from 2 grams to 20 grams NaOH/100 ml of composition, said composition containing from 5% to 30%, preferably from 7% to 15% by weight of silicate and comprising a solid water-soluble peroxygen compound suspended in a liquid phase containing water and at least one water-miscible organic solvent. The amount of the solid water-solubl~ peroxygen compound being such that the amount of available oxygen provided by said peroxygen compound is from 0.5 to 3%. The compositions preferably contain from 5~ to 40% of a non-phosphate builder.

Detailed Description The alkalinity The present compositions have an alkalinity of from 2 gram to 20 gram NaOH per 100 ml of composition, preferably from 3 gram to 10 grams NaO~ per 100 ml of compositions.

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The alkalinity can easily be measured as it is well known, i.e., titration of a 1~ solution from initial pH to pH 9.5. The desired alkalinity is at least partly provided by the silicate described hereinbelow, which can also be used in combination with sodium or potassium carbonate.

The silicate In order to provide (at least partly) the desired alkalinity, and to create a structure to suspend the peroxygen bleach particles, a silicate is present in the present composition, at levels of from 5% to 30%, preferably 7% to 15% of the total composition; PrPferred is sodium silicate, while potassium silicate can also be used.
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me silicate materials for use herein have a ratio of SiC2 to Na20 of from l:1 to 4:1, preferably 1:1 (metasilicate) and 2:1.

e silicate herein also provides desriable shear-thinning and thixotropic properties to the present compositions.

The water-soluble solid peroxyqen compound :

The compositions herein are free of chlorine-bleach.
Instead, they contain a solid water-soluble percxygen compound.

m e water-soluble solid peroxygen compound is present in the compositions herein at levels such that the amount of available oxygen provided by said peroxygen compound is from 0.5% to 3%.

Examples of suitable water-soluble solid peroxygen compounds include the perborates, persulfates, peroxydisulfates, perphosphates and the crystalline peroxyhydrates formed by reacting hydrogen peroxide with sodium carbonate (fonning percarbonate) or urea. Preferred peroxygen bleach compo~lds are perborates and percarbonates.

Perborate tetrahydrates are especially preferred, and are present at levels of from 5% to 30% by weight of the total composition.

Most preferred in the present context is a perborate tetrahydrate bleach in the form of particles having a weight-average particle diameter of from 0.5 to 20 micrometers, preferably 3 to 15 micrometers.

m e required small particle size can best be achieved by in-situ crystallization, typically of perborate monohydrate.

In~situ crystallization encompasses processes involving dissolution and recrystallization, as in the dissolution of perborate monohydrate and subsequent formation of perborate tetrahydrate. Recrystallization may also take place by allowing perborate monohydrate to take up crystal water, whereby the monohydrate directly recrystallizes into the tetrahydrate, without dissolution step.

In-situ crystallization also encompasses processes involving chemical reactions, as when sodium perborate is formed by reacting stoichiometric amounts o~ hydrogen peroxide and sodium metaborate or borax.

he liquid phase The suspension system for the so:Lid peroxygen component herein consists in a liquid phase that comprises water and a water-miscible organic solvent;

m is makes it possible to incorporate in the llguid detergent compositions herein an high amount of solid water-soluble peroxygen compound, while keeping the amount of available oxygen in solution below 0.5~ by weight of the liquid phase, preferably below 0~1%o Less than one fifth by weight perox~gen compound is dissolved in the liquid phase; the low level of available oxygen in solution is in fact critical for the stability of the system.

The standard iodometric method tas described for instance in Methoden der Organischen Chemie, Houben Weyl, 1953, Vo. 2, page 562) i5 suitable to determine the available oxygen (AVO~ content of the composition.

In order to ensure complete equilibration between liquid and solid phases, the compositions are to be kept after mixing for three days at room temperature before the AVO titration. Before measuring the products are thoroughly shaken in order to ensure correct sampling.

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For the determination of the available oxygen (AV0) in the liquid phase, samples of the compositions are centrifuged for 10 minutes at 10.000 rpm. The liquid is then separated from the solid and titrated for available oxygen.
, It is not necessary that the organic solvent be fully miscible with water, provided that enough of the solvent mixes with the water of the composition to af~ect the solubility of the peroxygen compound in the described manner. Fully water-soluble solvents are preferred for use herein.

; The water-miscible organic solvent must, o~ course, be compa~ible with the peroxygen bleach compound at the pH
that is used. Therefore, polyalcohols having vicinal ~ hydroxy groups (e.g. 1,2-propanediol and glycerol) are less ; desirable when the peroxygen bleach compound is perborate.

Examples of suitable water-miscible organic solvents include the lower aliphatic monoalcohols; ethers of diethylene glycol and lower monoaliphatic monoalcohols;
specifically ethanol, n-propanol; iso-propanol; butanol;
polyethylene glycol (e.g., PEG 150, 200, 300, 400);
dipropylene glycol; hexylene glycol; methoxyethanol;
ethoxyethanol; butoxyethanol; ethyldiglycolether;
benzylalcohol; butoxypropanol; butoxypropoxypropanol; and mixtures thereof. Preferred solvents include ethanol;
iso-propanol, 1-methoxy2-propanol and butyldiglycolether.
A preferred solvent system is ethanol.

Although the presence or ahsence of other ingredients plays a role, the amount of available. oxygen in solution is largely determined by the ratio water:organic solvent. It is not necessary however to use more organic solvent than is needed to keep the amount of avail.able oxygen in solution below 0.5~, preferably below 0~1%.
In practical terms, the ratio water:organic solvent is, for most systems, in the range from 0:1 to 1:3, preferably from 5:1 to 1:2.

The present liquid compositions are formulated at a pH
of from 9.5 to 12.5, preferably from 10 to 11.5. The alkaline pH allows to get a good bleaching action of the peroxygen compound, particularly when the peroxygen is a perborate.

O~t.ional ingredients The present compositions may contain a series of ingredients which, while being optional, are often desirable.

First of all, it is highly preferred that the present compositions contain a builder :

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The present compositions can contain from 5% to 40% of a builder which is a non-phosphate material; inorganic builders useful in the present compositions include aluminosilicates (zeolites), while or~anic builders include polyacids such as citric acid, nitrilotriacetic acid, certain alk(en)yl-substituted succinic acid/anhydride compounds, and mixtures of tartrate monosuccinate with tartrate disuccinate. Polymeric carboxylate builders inclusive of polyacrylates, polyhydroxy acrylates and polyacrylates/polymaleates copolymers can also be used.
Iminodiacetic acid derivatives such as N-glyceryl imino N,N
diacetic acid, N(-2-hydroxypropyl)imino N,N-diacetic acid are also suitable as builders. Preferred builders for use herein are citric acid and alk(en)yl-substituted succinic acid/anhydride compounds, wherein alk(en)yl contains from 10 to 16 carbon atoms and mixtures thereof. An example of this group of compounds is dodecenyl succinic acid/anhydride, especially preferred for the present compositions are mixtures of dodecenyl succinic/anhydride and citric acid, at ratios of dodecenyl succinic acid/anhydride to citric acid of from 2:1 to 1:1.

It is also preferred that the present compositions contain a surface-active agent, at levels of from 1% to 10%
by weight of the total composition;

Said surface-active agents are preferably nonionic surfactants :

The nonionic surfactants are conventionally produced by condensing ethylene oxide with a hydrocarbon having a reactive hydrogen atom, e.g., a hydroxyl, carboxyl, or .

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amido group, in the presence of an acidic or basic catalyst, and include compounds having the general formula RA(CH2CH2O)nH wherein R represents the hydrophobic moiety, A represents the group carrying the reactive hydrogen atom and n represents the average number of ethylene oxide moieties. R typical:Ly contains from about 8 to 22 carbon atoms. They can also be formed by the condensation of propylene oxide with a lower molecular weight compound. n usually varies from about 2 to about 24.

The hydrophobic moiety of the nonionic compound is prefPrably a primary or secondary, straight or branched, aliphatic alcohol having from about 8 to about 24, preferably from about 12 to about 20 carbon atoms. A more complete disclosure of .suitable nonionic surfactants can be found in U.S. Patent 4tl11,855. ~ixtures of nonionic surfactants can be desirable.

A preferred class of nonionic ethoxylates is represented by the condensation product of a fatty alcohol having from 12 to 15 carbon atoms and from about 4 to 10 moles of ethylene oxide per mole of fatty alcohol.

Suitable species of this class of e~hoxylates include -the condensation product of C12-C15 oxo-alcohols and 7 moles of ethylene oxide per mole of alcohol; the condensation product of narrow cut C14-C15 oxo-alcohols and 7 or 9 moles of ethylene oxide per mole of fatty(oxo~alcohol; the condensation product of a narrow cut C12-C13 fatty(oxo)alcohol and 6,5 moles of ethylene oxide per mole of fatty alcohol; and the condensation ~"` i !?, '~ ` ~,?

products of a C10-Cl4 coconut fatty alcohol with a degree of ethoxylation (moles EO/molle fatty alcohol) in the range from 5 to 8~ The fatty oxo alcohols while mainly linear can have, depending upon the ]processing conditions and raw material olefins, a certain degree of branching, particularly short chain such as methyl branching.

A degree of branching in the range from 15~ to 50%
(weight ~) is frequently found in commercial oxo alcohols.

Preferred nonionic ethoxylated components can also be represented by a mixture of 2 separately ethoxylated nonionic surfactants having a different degree of ethoxylation. For example, the nonionic ethoxylate surfactant containing from 3 to 7 moles of ethylene oxide per mole of hydrophobic moiety and a second ethoxylated species havin~ from 8 to 14 moles of ethylene oxide per mole of hydrophobic moiety. A preferred nonionic ethoxylated mixute contains a lower ethoxylate which is the condensation product of a C12-C15 oxo-alcohol, with up to ~0% (wt) branching, and from about 3 to 7 moles of ethylene oxide per mole of fatty oxo-alcohol, and a higher ethoxylate which is the condensation product of a C16-Clg oxo-alcohol with more than 50% (wk) branching and from about 8 to 14 moles of ethylene oxide per mole of branched oxo-alcohol.

m e compositions herein may, however, also contain other types of surfactant, like anionic or cationic surfactants, possibly in combination with the nonionic surfactants described above.

Synthetic anionic surfactants can be represented by the general formula RlSo3M wherein Rl represents a hydrocarbon group selected from the group consisting of straight or branched alkyl radicals containing from about 8 to a~out 24 carbon atoms and alkyl phenyl radicals containing from about 9 to about 15 carbon atoms in the alkyl group. M is a salt forming cation which typically is selected from the group consisting of sodium, potassium, ammonium, and mixtures thereof.

A preferred synthetic anionic surfactant is a water-soluble salt of an alkylbenzene sulfonic acid containing from 9 to 15 carbon atoms in the alkyl group~
Another preferred synthetic anionic surfactant is a water-soluble salt of an alkyl sulfate or an alkyl polyethoxylate ether sulfate wherein the alkyl group contains from about 8 to about 24, preferably from about 10 to about 20, preferably from about 1 to about 12 ethoxy groups. Other suitable anionic surfactants are disclosed in U.S. Patent 4,170,565, Flesher et al., issued October 9, 1979.

Examples of suitable cationic surfactants include quaternary ammonium compounds of the formula RlR2R3R4N+X , wherein Rl is Cl2-c20 alkyl or hydroxyalkyl; R2 is Cl-C4 alkyl or C12-C20 alkyl or hydroxyalkyl or Cl-C4 hydroxyalkyl; R3 and R4 are each Cl-C4 alkyl or hydroxyalkyl, or C6-C8 aryl or alkylaryl; and X is halogen. Preferred are mono-long chain quaternary ammonium compounds (i.e., compounds of the above formula wheren R2 is Cl-C4 alkyl or hydro~yalkyl).

~ etergent enzymes can be used in the present o~

composition. Suitable enzymes include the detergent proteases, amylases, lipases and cellulases;

Enzymatic stabilizing ag~nts for use herein include the salts of formic acid, e.g. sodium formate, but also the salts of higher carboxylic acids, such as sodium acetate, and mixtures of above species.

The total amount of enzymatic stabilizing agent typically ranges from 0.5 to 5%.

The present compositions may also contain relatively small amounts of :

- Bieach stabilizers such as following organo-phosphonic acids :

- ethylenediamino tetramethylenephosphonic acid, ; hexamethylenediamino tetramethylenephosphonic acid, diethylenetriamino pentamethylenephosphonic acid, amino-trime~hylenephosphonic acid, hydr~xyethylidene 1,1 diphosphonic acid and mixtures thereof.
- Other bleach stabilizers such as ascorbic acid, dipicolinic acid, sodium stannates and 8-hydroxyquinoline.

- polyaminocarboxylates ~uch as ethylene-diaminotetracetic acid, diethylenetriaminopentacetic acid, ethylenediamino disuccinic acid or the water-soluble alkali metals thereof.

- Silicone suds regulants - Sodium peroxide to adjust to the desired pH
- opacifiers, bactericides, dyes, perfumes, etc...

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The following compositions illustrate the present invention :

Ingredients % bY wei~ht Ex I Ex II Ex III Ex IV

water 24 26 24 26 ethanol 10 9 9 7 propylene glycol C12_14 succinic anhydride 8 8 8 8 citric acid 3 3 7 7 metasilicate (sodium) 10 10 10 Sodium silicate w/ratio SiO2/Na20 ~ - - 10 of 2:1 Sodium carbonate 12 Potassium carbonate - 10 12 10 Per~orate tetrahydrate 20 20 20* 20*
condensation product of 1 mole C13 15 oxo alcohol and 7 moles ethylene oxids 2 2 2 2 Protease 0.3 0.3 0.3 0.3 Amylase - - - 0.3 Sodium formate 1.5 l.S 1.5 1.5 Sodium Acetate 2.0 2.0 2.0 2.0 Pent~methylene phosphonic acid0.4 0.4 0.4 0-4 Hydroxy ethylidene diphosphonic acid0.2 0.2 0.2 0.2 Suds suppressor, Scdium hydroxide ) to adjust pH, minors ~ -- balance -~

available oxygen ~%) 2 2 2 2 alkalinity (~NaOH~100 ml) 7.5 4 4 4 pH 10.810.8 10.5 10.5 * recrystallized in-situ from 12.5% perborate monohydrate , , The compositions of example I to IV are pourable, show no phase separation after storage (3 weeks), and feature a remaining percentage of initial aVO of 90%, after 3 weeks.

The compositions of example I to IV perform equally well vs. commercially available dishwashing products containing chlorine bleach.

Claims

1. A chlorine-free liquid automatic dishwashing composition having an alkalinity of from 2 grams to 20 grams NaOH/100 ml of composition, said composition containing from 5% to 30% by weight of silicate and comprising a solid water-soluble peroxygen compound suspended in a liquid phase containing water and at least one water-miscible organic solvent; the amount of the solid water-soluble peroxygen compound being such that the amount of available oxygen provided by said peroxygen compound is from 0.5% to 3%.

2. A liquid detergent composition according to Claim 1, wherein the water miscible organic solvent is an aliphatic monoalcohol.

3. A liquid detergent composition according to Claim 2 wherein the water-miscible organic solvent is ethanol, and the water:ethanol ratio of from 8:1 to 1:3; preferably 5:1 to 1:2.

4. A liquid detergent composition according to Claim 1, wherein the solid, water-soluble peroxygen compound is perborate tetrahydrate, and present at levels of from 5% to 30% by weight of the total composition.

5. A liquid detergent composition according to Claim 2, wherein the solid, water-soluble peroxygen compound is perborate tetrahydrate, and present at levels of from 5% to 30% by weight of the total composition.

6. A liquid detergent composition according to Claim 3, wherein the solid, water-soluble peroxygen compound is perborate tetrahydrate, and present at levels of from 5% to 30% by weight of the total composition.

7. A composition according to Claim 4 wherein the perborate tetrahydrate bleach is in the form of particles having a weight-average particle diameter of from 0.5 micrometer to 20 micrometer.

8. A composition according to Claim 5 wherein the perborate tetrahydrate bleach is in the form of particles having a weight-average particle diameter of from 0.5 micrometer to 20 micrometer.

9. A composition according to Claim 6 wherein the perborate tetrahydrate bleach is in the form of particles having a weight-average particle diameter of from 0.5 micrometer to 20 micrometer.

10. A composition according to Claim 7 wherein the perborate tetrahydrate particles have been formed by recrystallization of perborate monohydrate.

11. A composition according to Claim 8 wherein the perborate tetrahydrate particles have been formed by recrystallization of perborate monohydrate.

12. A composition according to Claim 9 wherein the perborate tetrahydrate particles have been formed by recrystallization of perborate monohydrate.

13. A composition according to Claim 1, wherein the solid, water-soluble peroxygen compound is a percarbonate.

14. A composition according to Claim 2, where m the solid, water-soluble peroxygen compound is a percarbonate.

15. A composition according to Claim 3, wherein the solid, water-soluble peroxygen compound is a percarbonate.

16. A composition according to Claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15 containing from 7% to 15% of silicate.

17. A composition according to Claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15 having an alkalinity of from 3 grams to lo grams NaOH/100 ml of composition.

18. A composition according to Claim 16 having an alkalinity of from 3 grams to 10 grams NaOH/100 ml of composition.

19. A composition according to Claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15 which contains from 5% to 40% of a builder selected from dodecenyl succinic acid, citric acid, iminodiacetic acid derivatives, and mixtures thereof.

20. A composition according to Claims 16 which contains from 5%
to 40% of a builder selected from dodecenyl succinic acid, citric acid, iminodiacetic acid derivatives, and mixtures thereof.

21. A composition according to Claims 17 which contains from 5%
to 40% of a builder selected from dodecenyl succinic acid, citric acid, iminodiacetic acid derivatives, and mixtures thereof.

22. A composition according to Claims 18 which contains from 5%
to 40% of a builder selected from dodecenyl succinic acid, citric acid, iminodiacetic acid derivatives, and mixtures thereof.