EP0340371B1

EP0340371B1 - Bleaching composition containing alkaline hypochlorite and process for its manufacture

Info

Publication number: EP0340371B1
Application number: EP88500116A
Authority: EP
Inventors: Enrique Baixas Veiga; Antonio Rosas Girones; Bill Smith
Original assignee: Henkel Iberica SA
Current assignee: Henkel Iberica SA
Priority date: 1988-05-05
Filing date: 1988-11-28
Publication date: 1994-04-20
Anticipated expiration: 2008-11-28
Also published as: EP0340371A2; ES2007221A6; DK219189A; DE3889217D1; DK219189D0; EP0340371A3; ATE104697T1; DE3889217T2; PT90455B; PT90455A

Abstract

Whitening composition with an alkalinic hypochlorite base and the process to obtain this, where the composition consists of a solution of metal alkalinic hypochlorite, with a concentration of 1 to 10% in weight terms of the total weight, in an anionic surface active agent or mixture of surface active agents, where the predominant proportion is that of the anionic surface active agent, of the alkalinic metal alkylether sulphate type, in a concentration of between 0.1 and 10% in weight terms of the total weight; a neutral salt in a proportion of 0 to 4% in weight terms of the total weight, and additives and auxilliary products such as perfumes, optical whiteners and colourants of up to 0.5% in weight terms of the total weight. The process to obtain this is distinguished by the fact that the mentioned components are mixed in the proportions indicated, in a given case by agitation. The composition obtained in this way is used in the fields of hygiene and disinfection.

Description

This invention relates to a bleaching composition comprising an alkaline metal hypochlorite and a process for obtaining thereof. These compositions are used in the fields of hygiene and disinfection.
In the last few years bleaching compositions including alkaline metal hypochlorites have been acreditted due to the fact that they are remarkably viscous and, therefore, are appropriate for the treatment of not only horizontal and slanted surfaces but also for vertical surfaces since the viscosity of these compositions causes that the contact time between them and the surfaces to be treated is of much longer duration than that of fluid compositions which rapidly "run" from these surfaces.
This problem established the necessity of obtaining "viscous" bleaching compositions in order to increase the contact time between surfaces to be treated and the cleaning and disinfection compositions.
In this respect in the prior art have been described various attempts to resolve said problem, such as the addition of two o more surface active agents to said alkaline metal hypochlorites for obtaining thus viscosity levels of 100 to 150 centipoises in the finished product.
The principal surface active agent used to date has been an amine oxide, mixed with other surface active agents, which are generally anionic.
Thus in the US patent 3,684,722 has been proposed the use of an amine oxide with betaines; in the US patent 4,229,313 has been described the use of mixes of amine oxides; and in EP patent 137,871 the use of amine oxides together with other surface active agents was proposed.
In Spanish patent 506,624 has been proposed the use of an amine oxide in a higher proportion together with sodium lauryl ether sulphate in a lesser proportion, to prepare decoloring compositions for use in textile fibre dye baths comprising alkaline metal hypochlorites.
Likewise in the UK patent 1,128,411 to Cyclo Chemicals was claimed the use of an hypochlorite solution containing mixes of surface active agents which comprise an amine oxide and sodium lauryl ether sulphate.
On the other hand, by the DE patent 3,527,910 to Basf is known the use of mixes of sodium lauryl ether sulphate and sodium alkyl sulphate.
All of these compositions of the prior art have the disadvantage of giving viscosity levels of 200 centipoises only where their ionic strength is in the region of 4, this being achieved when the alkaline hypochlorite concentration is in the region of 8 to 9 % by weight. In this concentration range, said compositions have a very high decomposition power on organic products such as surface active agents and hydrotopes, thereby noticeably reducing the stability of the product in relation to its content of active chlorine.
Moreover, in the majority of the compositions of this type, known by the prior art, it is possible to observe inadmissable variations in viscosity levels, some of these drops being very marked in some cases.
On the other hand, the reaction of high alkaline hypochlorite concentrations with the organic products leads to the formation of high quantities of organochlorinated compounds (AOX = adsorbable organic halogens) which can reach concentrations in the region of 5.5 ppm (according to analysis method DIN 38409-H 14). These organochlorinated compounds are skin irritant and are not easily biodegradable, for which reason the concentration level of said compounds in sewage waters is strictly controlled by the public health standards in some countries. Therefore, it is desirable to reduce or even eliminate said compounds from sewage waters to improve environmental protection.
This invention resolves all and each one of these disadvantages given that it is based on the use of one sole surface active agent. In addition, by means of the compositions which are the subject of this invention, the concentration level of organochlorinated compounds is reduced drastically and that with the use of the same concentration of the surface active agent as in the case of amine oxide, and this reduction can reach values of O.7 ppm.
In this way the sewage waters originating from the usage of these compositions are more compatible with environmental protection.
According to another characteristic of the compositions of this invention, viscosity levels in the region of 700 to 800 centipoises are achieved, with chlorine concentrations lower than those of the compositions of the prior art, specifically in the region of 3 to 5% by weight, corresponding to an ionic strength of 1 to 2.
In addition, the compositions according to the invention are more stable in relation to hypochlorite than those of the prior art and thereby the finished product is more stable and has less inherent risk of accidents.
In the bleaching according to the invention, comprising an alkaline hypochlorite, the viscosity level remains stable with the passing of time.
Another advantage of the bleaching compositions according to the invention is that there are no hydrotopes causing the solubilitation of the surface active agent used.
Another advantage of the compositions according to the invention is that there is no nitrogen in the molecular structure of the surface active agents, thereby avoiding the risk of the formation of chloramines.
All these advantages of the bleaching compositions comprising alkaline hypochlorites are achieved because these compositions contain one sole surface active agent, of a determined nature, and at concentration levels which move between determined margins, totally eliminating the use of amine oxides.
According to the invention, the bleaching composition including an alkaline hypochlorite comprises:

from 1 to 10% by weight, preferably from 2 to 6% by weight, respect to the total weight of the composition, of an alkaline metal hypochlorite;
from O,1 to 10% by weight, preferably from O,2 to 5% by weight, and more preferably from O,5 to 2% by weight, respect to the total weight of the composition, of one sole anionic surface active agent; and
from 0 to 4% by weight, preferably from O,2 to 3% by weight, and more preferably from O,5 to 2% by weight, respect to the total weight of the composition, of a neutral salt.

The anionic surface active agent used in the bleaching compositions including an alkaline hypochlorite according to the invention, is an alkylether sulphate of an alkaline cation, which specifically has 2 to 4 units of ethylene oxide and, preferably, 2 to 3 units of ethylene oxide.
According to one preferential aspect of the invention, the alkyl chain of the alkylether sulphate of the alkaline metal is linear and has 6 to 20, preferably 12 to 18 and, more particularly 12 to 14, carbon atoms, the alkaline cation being selected preferably from sodium, potassium and lithium.
According to another aspect of the invention, the neutral salt which forms a part of the bleaching composition based in an alkaline hypochlorite is sodium chloride.
According to the invention, the compositions will preferably achieve viscosity levels of up to 800 centipoises at 20^oC, measured by a Brookfield viscosimeter, RVT model, with a no. 1 or no. 2 spindle at 20 r.p.m.
In addition and according to another preferential aspect of the bleaching compositions of this invention, these can contain an alkaline metal compound, such as a caustic hydroxide like sodium hydroxide or potassium hydroxide, preferably, however, sodium hydroxide, in such quantities that the pH value of the final composition is between 12.5 and 14 approximately.
The bleaching compositions according to the invention can contain additives and auxilliary products which are usual in this type of mixes, such as perfumes, optical whiteners and colourants, in a proportion of O.O1 to 0.5% by weight.
The optical whitener can be of the phorwhite BHC 766 type, which is a derivate of the 4,4'-bis-(1,2,3-triazolyl)-(2)-stilbene-2,2-sulphonic acid, in the form of potassium salt.
According to another aspect of the invention, the bleaching composition comprising an alkaline hypochlorite is prepared by mixing a solution of alkalinic metal hypochlorite with an alkaline metal alkylether sulphate, with a neutral salt, together with the additives and auxilliary agents which are usual in this type of mixes, such as perfumes, which can be chosen from a great variety of useable perfumes such as monoterpenic, monocyclic and bicyclic alcohols and their esters with alkanoic acids having 2 to 3 carbon atoms such as isoborneol, dihydroterpineol and isobornyl and dihydroterpinyl acetates or similar, as indicated in Spanish patent 554,709, in the name of the same applicant. In addition, optical whiteners can be added, together with perfumes and pigments such as copper phthalocyaninas and ultramarine which are stable in these mixes, and opcionally an alkalinising agent to regulate the pH value, such as sodium or potassium hydroxide, giving a final pH value of between 12.5 and 14 in the mix, with agitation, decantation and filtration to obtain a product which is viscous and free of foreign particles and/or any type of aglomerate.
The order in which the components are mixed is arbitrary, however, it is preferable to add the rest of the components to the alkaline hypochlorite solution, either separately or in any combination, under an eventual agitation, followed by an eventual decantation operation and/or filtration and final packaging.
The installations used to carry out this process according to the invention are of the usual type used for this kind of operations, which are usually carried out at room temperature.
The invention is described below in more detail by means of examples of preferable ways of carrying out the process; however, these are not of a restrictive nature.

EXAMPLE 1

Into a tank which can be agitated, an aqueous solution of sodium hypochlorite is placed, with an active chlorine content which varies between 3 and 7 % by weight and a pH value of between 13.0 and 13.5, and to this solution is added an alkaline metal alkylether sulphate, specifically Pulcra's Montosol PL 18, which is a natural alcohol with a linear chain of 12 to 14 carbon atoms in a proportion of 70:30, and an average ethylene oxide content of 2.3 mols per mol of alcohol, sulphated and neutralised with sodium salt, followed by the addition of the other components and, optionally, decantation and filtration.
Thirteen compositions are prepared in accordance with the general formulation and the components and proportions are as shown in table I below.

The indicated viscosity levels in each case were obtained after 24 hours, and after 8 weeks of storage at room temperature.

TABLE 1

Example Nr.	NaOCl % w	Montosol PL 18 content (LES 100 %) % w	Viscosity at 20^o after 24 hrs.	Viscosity at 20^o after 8 weeks
I-1	3.0	1.0	16	16
I-2	3.5	1.0	24	24
I-3	4.0	1.0	36	36
I-4	4.5	1.0	100	95
I-5	5.0	1.0	182	175
I-6	5.0	1.5	470	450
I-7	5.0	2.0	790	730
I-8	5.5	1.0	230	225
I-9	5.5	1.5	480	460
I-10	5.5	2.0	680	645
I-11	6.0	1.0	160	155
I-12	6.0	1.5	190	182
I-13	6.0	2.0	260	250
LES = alkaline metal lauryl ether sulphate

* = measured in a Brookfield viscosimeter, RVT model, with spindles no. 1 or no. 2 at 20 r.p.m.

EXAMPLE II

Into a tank which can be agitated, an aqueous solution of sodium hypochlorite is placed, with an active chlorine content which varies between 3 and 7% by weight and a pH value of between 13.0 and 13.5, and to this solution is added an alkaline metal alkylether sulphate, specifically Henkel KGaA's Texapon N-70, which is a natural alcohol with a linear chain of 12 to 14 carbon atoms in a proportion of 70:30, and an average ethylene oxide content of 2.0 mols per mol of alcohol, sulphated and neutralised with a sodium salt, followed by the addition of the other components and, optionally, decantation and filtration.
Eight compositions are prepared in accordance with the general formulation and the components and proportions are as shown in tabla II below.

The viscosity levels indicated in each case were obtained after 24 hours, and after 4 weeks of storage at a temperature of 40^oC.

TABLE II

Example Nr.	NaOCl % w	% w Texapon N70	Viscosity at 20^oC after:
			24	1 wk	2 wk	3 wk	4 wk
II-1	3.5	1.0	136	130	120	116	112
II-2	4.0	1.0	256	248	196	164	146
II-3	3.5	1.5	422	420	346	360	316
II-4	4.0	1.5	260	242	192	190	172
II-5	4.5	1.5	222	32	16	16	14
II-6	3.5	2.0	732	742	618	644	596
II-7	4.0	2.0	736	792	672	712	656
II-8	4.5	2.0	760	532	398	414	336

Claims

A bleaching composition based on alkaline hypochlorites, characterized in that it comprises:
- from 1 to 10% by weight, with respect to the total weight of the composition, of an alkaline metal hypochlorite;

- from O.1 to 10% by weight, with respect to the total weight of the composition, of an anionic surface active agent of the type alkylether sulphate of alkaline metal as the sole surface active agent;

- from 0 to 4% by weight, with respect to the total weight of the composition, of a neutral salt; and

- up to 0.5 % by weight, with respect to the total weight of the composition, of additives and auxilliary products such as perfumes, optical whiteners, colourants and pigments.
A bleaching composition according to claim 1, characterized in that the proportion of alkaline metal hypochlorite is from 2 to 6% by weight and the proportion of anionic surface active agent is from O.5 to 3.0% by weight, respect to the total weight.
A bleaching composition according to claims 1 and 2, characterized in that the alkaline metal alkylether sulphate can be chosen from those having 6 to 20 carbon atoms, preferably 12 to 18 and more particularly 12 to 14 carbon atoms in their alkyl chain, the preferable alkaline metal being either sodium, potassium or lithium.
A bleaching composition according to claims 1 to 3, characterized in that the alkaline metal alkylether sulphate has an ethoxylation grade of between 2 and 4 mols, and preferably between 2 and 3 mols of ethylene oxide per mol.
A bleaching composition according to claims 1 to 4, characterized in that it has a viscosity level from 14 to 792 centipoises, preferably from 150 to 300 centipoises.
A bleaching composition according to claims 1 to 5, characterized in that it has a strong ionic strength of between 1 and 5 and a pH value of between 12.5 and 14.
A bleaching composition according to claims 1 to 6, characterized in that it contains an optical whitener derived from 4,4'-bis-(1,2,3-triazolyl)-(2)-stilbene-2,2-sulphonic acid, in the form of potassium salt.
A bleaching composition according to claims 1 to 7, characterized in that it contains a perfume chosen, amongst others, from monoterpenic, monocyclic and bicyclic alcohols and their esthers with alkanoic acids having 2 to 3 carbon atoms, such as isoborneol, dihydroterpineol and isobornyl and dihydroterpinyl acetates.
A process for the obtention of a bleaching composition according to claims 1 to 8, characterized in that comprises mixing a solution of alkaline metal hypochlorite with an alkaline metal alkylether sulphate and with a neutral salt and additives and auxilliary agents for this type of mixture, such as perfumes, optical whiteners and colourants which are stable in such mixtures and adjusting the pH value of the mixture formed to a value of between 12.5 and 14 by means of adding an alkalinising agent such as sodium or potassium hydroxide, followed by decantation and/or filtration and final packaging.