MXPA97008870A

MXPA97008870A - Procedure for the manufacture of hipoclor whitening compositions

Info

Publication number: MXPA97008870A
Application number: MXPA/A/1997/008870A
Authority: MX
Inventors: Marchesini Maurizio; Trigiante Giuseppe
Original assignee: The Procter & Gamble Company
Priority date: 1995-05-16
Filing date: 1997-11-17
Publication date: 1998-10-15

Abstract

The present invention describes a process for the manufacture of aqueous and liquid bleaching compositions comprising hypochlorite, a concentrated source of alkalinity and water, said process comprising the steps of: mixing said hypochlorite and alkali metal, said concentrated source of alkalinity and said water , separating the insoluble species formed in said first step, and then adding a chelating agent capable of chelating heavy metal ions, the compositions provided by the process according to the present invention are substantially free of heavy metal ions, thus providing a yield of whiteness and / or improved fabric safety performance

Description

PROCEDURE PflRfl Lfl MANUFACTURE OF HYPOCHLORITE WHITENING COMPOSITIONS TECHNICAL FIELD The present invention relates to a process for the manufacture of a liquid bleaching composition that is suitable for laundry applications that include washing by hand, as well as washing with automatic washing machines.

A «BACKGROUND TO THE INVENTION Liquid bleaching compositions are well known in the art. Among the different bleaching compositions available, those based on bleaching by hypochlorite are commonly the most preferred.

For example, UO-88-05461 is representative of the art, describes an aqueous composition comprising hypochlorite, sodium carbonate and sodium hydroxide and the use of said composition to remove stains from the fabrics. However, the disadvantages associated with the use of the chlorine-based compositions are that said compositions can both damage and yellow the fabrics. It has now been discovered that the whiteness yield and / or the safety performance of the fabric of a liquid aqueous composition containing hypochlorite depends mainly on two factors: the pH of the bleaching environment and the presence of heavy metal ions in said environment bleaching. It is believed that a higher pH of the bleaching environment is beneficial for the whiteness and safety performance of the fabric because it displaces the chemical balance between hypochlorite and hypochlorous acid to reduce the level of acid or hypochlorine, the species that has been discovered is the responsible for the arillamiento and the damage to the + ela. The presence of heavy metal ions such as Ni, Co, Cu, Mn, Cr, and Fe adversely affects the bleaching performance of the hypoclope. It is believed that in the washing environment said heavy metal ions catalyze the attack of hypochlorous acid in the fabrics with the generation of yellow oxidized species. Said heavy metal ions also lead to a tension force of the fabrics, thus reducing the resistance to the fabric. It is further believed that said heavy metal ions are adsorbed per se on the oxidized fabrics or dyed species, and that they catalyze the degradation of the brighteners adsorbed on the fabrics, thus generating highly dyed species on the fabrics. In the same way, said heavy metal ions stabilize pigments stained with enzymatic stains such as blood or grass. Moreover, it is believed that said heavy metal ions are harmful to the performance of a hypochlo- prate composition, since they tend to react with the hypochlorite present in said composition and therefore catalyze the decomposition of said hypochlorite. In current industrial manufacturing processes, liquid aqueous compositions comprising hypochlo- phate and a concentrated source of alkalinity, such as sodium hydroxide, are prepared using the cheapest and most commonly available raw material. Such commercially available raw material is normally contaminated by impurities such as heavy metal ions. For example, commercially available and commonly used hypochlorite may contain proportions of other materials such as sodium carbonate and / or caustic soda and / or heavy metal ions. Likewise, normal acoustic soda is contaminated with heavy metal ions such as iron. More particularly, in current industrial manufacturing processes, such liquid aqueous compositions comprising hypochlorite are prepared by diluting a concentrated hypochlorite solution with tap water, ie, non-demineralized water, in the presence of said alkalinity source, allowing precipitation of the insoluble salts, such as metal hydroxides and metal carbonates, and finally removing said insoluble salts from said compositions. However, the compositions obtained are not satisfactory in terms of their purity, because they still contain a certain level of heavy metal ions that have not been retained / removed by a conventional separation means, such as by filtering said compositions with a desoan-ation fi lter. The amount of heavy metal ions in the finished composition is usually lower when a liquid aqueous composition is manufactured which makes hypochlorite at high pH values such as 13 and above. In fact, the solubility of most of the heavy metal ions that must be removed to ensure good whiteness and / or safety performance of the fabric increases with the pH of the composition. It has now been discovered that it is essential that heavy metal ion levels be controlled per se in liquid aqueous compositions containing hypochlorite, thereby providing enhanced whiteness and / or fabric performance performance when treating fabrics with such compositions It is therefore an object of the present invention to provide a process for the manufacture of liquid aqueous compositions comprising hypoclope and a concentrated source of alkalinity, said compositions having a particularly low content of heavy metal ions, then exhibiting a whiteness and / or improved fabric security. It is a further object to provide such a process for the manufacture of liquid aqueous compositions containing hypochlorite at reasonable overall costs, e.g., to provide compositions exhibiting an improved whiteness yield and / or fabric security performance, by a procedure in which the maternal premium used is the most bar-ata and the most commonly available commercially. It has now been discovered that particularly efficient control of heavy metal ions can be achieved using a manufacturing process wherein a chelating agent capable of chelating heavy metal ions is added to a liquid aqueous composition which comprises a concentrated source. of alkalinity, such as sodium hydroxide, hypochlorite and water after said composition has passed through a separation step wherein the more soluble species present in said composition have been renewed / removed from said composition. In fact, the separation step must remove from said liquid aqueous composition containing hypochlorite any more soluble species such as sodium hydroxides and / or metal salts present in said composition. Said chelating agent allows to remove residual heavy metal ions that have not been removed / removed by the separation step, i.e., by any conventional separation means such as filtration with a dewatering filter. Adding the chelating agents capable of chelating heavy metal ions after the separation step allows to use amounts of said chelating agents that would otherwise be required if they were added before said separation step in order to obtain a composition of the same purity. In fact, when added before said separation step, said chelating agents interact with metal ions such as magnesium and / or calcium present in the composition that would otherwise remove as metal salts due to the presence of anions such as carbonate found. commonly in hypochlorite solutions suitable for use in making said hypochlorite-containing composition according to the present process, thereby leaving less chelating agents available for heavy metal chelators present in said composition. The compositions obtained by the process of the present invention have improved physical and chemical stability. An additional feature of the compositions obtainable by the process of the present invention is that in addition to their surprising whiteness action, said compositions also allow good stain removal.

BRIEF DESCRIPTION OF THE INVENTION The present invention encompasses a process for the manufacture of a liquid and aqueous bleaching composition having a pH of 10 to 14 and comprising an alkali metal hypochlorite, a concentrated source of alkalinity and water. Said method includes the steps of: - mixing said alkali metal hypochlorite, said concentrated source of alkalinity and said water, - separating in a second step the insoluble species formed in said first step, and then adding a chelating agent capable of chelating ions of heavy metal. In a preferred embodiment of the process of the present invention, a precipitating agent capable of binding heavy metal ions is also added to said composition before the separation step thus forming salts having a product of water solubility not exceeding .1.0 -6 at a temperature of 25 ° C.

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the manufacture of an aqueous and liquid whitening composition. The process of the present invention for the manufacture of a liquid and aqueous bleaching composition, as hereinafter described, having a pH of 10 to 14 and comprising an alkali metal hypochlorite, a concentrated source of alkalinity and water , includes the following steps. In a first step, an alkali metal hypochlorite, a concentrated source of alkalinity and water are mixed. In the next step the insoluble species formed in said first step are separated from said composition. And then a chelating agent capable of chelating heavy metal ions is added after said separation step. By "insoluble species formed" is meant herein any solid phase present in the composition made in accordance with the present invention, ie, any kind of species that is insoluble in said composition and thus capable of being separated from said composition when any conventional separation means is used. The insoluble species formed include, for example, metal hydroxides arising from the precipitation of sodium hydroxide with metal ions, and metal salts arising from the precipitation of impurities such as sodium carbonate, commonly present in the solutions of commercially available hypochlorite suitable for use in the process of the present invention, with metal ions. Metal ions such as calcium / magnesium as well as heavy metal ions, present in the compositions made in accordance with the process of the present invention arise from starting materials and tap water used in said process. By "separating the insoluble species formed" it is meant herein that any known means can be used to remove a solid phase from a liquid phase according to the present invention. Accordingly, the formed precipitates can be removed from the compositions of the present invention by sedimentation and / or filtration and / or centrifugation. Filtration is preferred herein. Filters suitable for use in the process according to the present invention are any commercially available filters known as dewatering filters, including cartridge filters, mesh filters, filter cakes and the like. The chelating agents according to the present invention are any chelating agent having a binding constant K to heavy metal ions defined as follows, or mixtures thereof: when n = 1, then K > 105, preferably K > . 105 and most preferably K > 10 *, when n = 2, then K > 106, preferably K > . 106 and rnuy preferably K > 107, when n = 3, then K > 107, preferably K > . 107 and most preferably K > 108. where n is the number of molecules of chelating agent per heavy metal ion and where K = (MLn) / (M) (L) «and (MLn) is the concentration of the heavy metal ion complexes / chelating agent, (M) is the concentration of free heavy metal ions and (L) is the concentration of free chelating agents. Examples of chelating agents suitable for use herein are pyridine polycarboxylic acid or salts thereof having one of the following formulas: wherein R is hydrogen, a halogen atom, a hydroxyl group, an amino group, a carboxyl group or a short chain alkyl group (C? -C <;) and n is 1 or 2. Preferred herein are polycarboxylic acid derivatives of pyridine selected from the group of dipicolinic acid (2,6-pyridenedicarboxylic acid) and derivatives thereof obtained by substitution of the hydrogen in the para position with a halogen, a carboxyl group or a short chain alkyl group (C1-C4). Said chelating agents that will be used herein are stable to hypochlorite and high alkalinity. By "stable to hypochlorite and high alkalinity" it is tried here to say that the concentration of said chelating agents does not change after a period of two months at room temperature, at about 25 ° C. The compositions made according to the process of the present invention comprise from 0.01% to 5% by weight of the total composition of said chelating agent, or mixtures thereof, preferably from 0.01% to 3%, preferably from 0.01% to 2%. % and more preferably from 0.01% to 1%. It has now been discovered that the addition of a chelating agent capable of chelating heavy metal ions after the separation step, in a process for the manufacture of aqueous and liquid compositions containing hypochlorite, reduces the content of heavy metal ions in said compositions. In fact, the present invention provides liquid aqueous compositions containing hypochlorite that are substantially free of heavy metal ions, ie, compositions in which the heavy metal ions have been chelated and thus are present in an unactivated form. In fact, it has now been discovered that the use of said chelating agents after the separation step, in a process for manufacturing hypochlorite-containing compositions comprising a concentrated source of alkalinity and water, wherein said different ingredients are mixed before being subjected to the separation step, allows to provide compositions containing hypochlorite with improved whiteness yield and / or fabric safety performance. By "substantially free of heavy metal ions" it is meant herein that the concentrations of different heavy metal ions in said compositions made in accordance with the present invention are very low, e.g., the level of Te is not greater than 1 ppm, the Ni level is not higher than 20 ppb, the Cu level is not higher than 20 ppb, the Mn level is not higher than 10 ppb, and / or the Co level is not greater than 10 ppb. In fact, in the process of the present invention, said chelating agents are added in excess to chelate all the heavy metal ions present in the composition made according to said process, and to be further available to chelate the ions. of heavy metal present in the washing / bleaching solution. The compositions made according to the process of the present invention are physically and chemically stable. By "chemically stable" it is meant herein that the hypochlorite bleach compositions of the present invention should not suffer a loss of more than 25% of the available chlorine after 10 days of storage at 5 ° C +/- 0.5 ° C. . The percentage of loss of available chlorine can be measured using the method described, for example, in "flnalyses des Eaux et Extrais de Javel" by "La chambre syndicale nationale de L'eau de Javel et des produits connexes", pages 9-10 (1984) This method consists of measuring the available chlorine in the fresh compositions, that is, just after they are manufactured, and in the same compositions 10 days after storage at 50 ° C.

By "physically stable" it is meant herein that no phase alteration occurs after prolonged storage periods, such as 10 days at 50 ° C. By "phase alteration" one tries to say in the present any change in the physical properties of the phases of the solution, for example phase separation. In a preferred embodiment of the process of the present invention, a precipitating agent, or mixtures thereof, may be added before the separation step of the process of the present invention. The precipitating agents according to the present invention can be defined as any agent that is capable of binding to heavy metal ions, thereby forming insoluble salts, ie, salts having a product of water solubility not exceeding 10%. 6 at a temperature of 25 ° C, most preferably not above IO-8 and more preferably not more than 10 -10. It has now been discovered that the addition of said precipitating agent or mixtures thereof to an aqueous and liquid composition containing hypochlorite in the process of the present invention before said composition is subjected to the separation step, assists in the chelating action achieved by the chelating agents. In fact, it has been discovered that the precipitation agents added before the separation step and the chelating agents added after said separation step of the process of the present invention act together to provide a hypochlorite-containing composition that is substantially free of ions. of heavy metal. When precipitation agents are added before the separation step in the process of the present invention, more heavy metal ions are precipitated as salts and thus are removed by the separation step compared to the same procedure without the addition of said precipitation agents. Accordingly, this allows to use rnenos of said chelating agents after the separation step that would otherwise be required in the absence of said precipitating agents before said separation step, this in order to obtain a composition containing hypochlorite with the same purity . Also, adding said chelating agents after the separation step, in comparison with their addition before said separation step, allows use of said chelating agents. In fact, when added before the separation step, said chelating agents interact with the magnesium and / or calcium present in the hypochlorite-containing composition, leaving less chelating agents available to chelate the heavy metal ions present in said composition. It is further believed that, when added before the separation step, said chelating agents also interact with the precipitation agents, if present, thus leaving less chelating agents available to chelate the heavy metal ions present in said composition, as well as less. precipitation agents available to precipitate heavy metal ions as salts. Examples of suitable precipitating agents for use herein are the alkali metal salts of oxalate, phosphonate, borate, sesquicarbonate, selenide, vanadate, telluride, thiocarbonate, polyoxide, or mixtures thereof. Preferred alkali metal salts of said precipitating agents are sodium oxalate, sodium fostonate, sodium borate, sodium sesquicarbonate, sodium selenide, sodium vanadate, sodium telluride, sodium thiocarbonate, sodium polyoxide, or mixtures thereof. Particularly useful precipitation agents that are used herein also include silicate or carbonate salts, or mixtures thereof. Preferred alkali metal silicate and carbonate salts are sodium silicate and sodium carbonate, both of which are commercially available, or mixtures thereof. Preferred compositions made according to the process of the present invention comprise a mixture of sodium carbonate, sodium silicate and sodium oxalate. The compositions made according to the process of the present invention comprise from 0.01% to 10% by weight of the total composition of each precipitation agent present, preferably from 0.01% to 7%, most preferably from 0.1% to 5% and preferably from 0.2% to IB 3%. As a further essential feature, the compositions made according to the process of the present invention comprise an alkali metal hypochlocite or mixtures thereof. Various forms of alkali metal hypochlo- type are commercially available and, although this is not critical to the present invention, sodium hypochlorite is preferred herein. Compositions made in accordance with the present invention comprise an alkali metal hypochlorite bleaching agent, typically representing from 0.1% to 10% by weight of the total composition, based on the active chlorine, of alkali metal hypochlocite. Preferred compositions herein comprise from 3% to 6% alkali metal hypochloride. As another essential feature, compositions made according to the process of the present invention comprise a concentrated source of alkalinity, or mixtures thereof. Compositions made in accordance with the present invention comprise from 0.04% to 2% by weight of the total composition of said concentrated source of alkalinity, or mixtures thereof, preferably from 0.1% to 1.5% by weight and most preferably from 0.2% to 0.9% by weight. Examples of concentrated alkalinity sources are alkali metal hydroxides, such as potassium and / or sodium hydroxide, or alkali metal oxides such as sodium and / or potassium oxide.

Accordingly, the compositions made according to the process of the present invention have a pH of from 10 to 14, preferably from 11 to 14 and rnuy preferably from 12 to 14. It is in the alkaline scale that the stability and optimal performance of hypochlorite. The compositions made according to the process of the present invention further comprise water in the amount necessary to complete said compositions. The water used in the process of the present invention is tap water, ie non-demystified water. The compositions made according to the process of the present invention may further comprise optional ingredients, including bleach-stable surfactants, organic and inorganic alkalis, perfumes, bleach-stable perfume solubilizer, colorants, optical brighteners, solvents and the like. If present, said optional ingredients are added to the compositions made according to the method of the present invention at any step, ie before or after the separation step. The compositions made according to the process of the present invention are used in diluted form for laundry application. The term "used in diluted form" herein includes dilution by the user, which occurs for example in laundry applications by hand, as well as dilution by other means, such as in a washing machine. Typical dilution levels are from 0.5% to 20% for a laundry application by hand and 0.1% to 10% in a washing machine. The present invention will be further illustrated by means of the following examples.

EXAMPLES The following compositions are manufactured according to the process of the present invention: Compositions 1 2 3 Sodium hypochlorite 5.0 5.0 5.0 Sodium hydroxide 1.0 1.0 1.0 Sodium carbonate / 1.3 1.3 Dipicolinic acid 2.0 1.0 1.0 Sodium oxalate / 1.0 / PH 13 13 13 Water and minor ingredients 100% - The above compositions are manufactured at room temperature, i.e., at about 25 ° C. In the first step of the process according to the present invention, sodium hypochlorite, sodium hydroxide, tap water, and sodium carbonate if present as well as sodium oxalate are mixed. In the next step the resulting composition is filtered with a dewatering filter. And finally, dipicolic acid is added after the filtration step. The compositions 1, 2 and 3 obtained in accordance with the process of the present invention provide excellent whiteness and safety of the fabric to the fabrics treated therewith. These compositions also exhibit excellent stability. In fact, after 10 days of storage at 50 ° C, the content of active chlorine in compositions 1, 2 and 3 manufactured according to the process of the present invention is higher compared to the content of active chlorine in compositions similar products manufactured without adding any chelating agent capable of chelating heavy metal ions (eg, dipicolimic acid) after the filtration step.

Claims

NOVELTY OF THE INVENTION CLAIMS

1. - A process for the manufacture of a liquid and aqueous bleaching composition having a pH of about 10 to about 14 and comprising an alkali metal hypochlorite, a concentrated alkalinity and water stream, said process includes the steps of: - mixing in a first step said alkali metal hypochlorite, said concentrated source of alkalinity and said water, -separate a second step the insoluble species formed in said first step, -and then add a chelating agent capable of chelating heavy metal ions.

2. A process according to claim 1, further characterized in that said chelating agent has a binding constant K to heavy metal ions defined in the following manner, or mixtures thereof: when n = l, then K > ID5, when n = 2, then K > 106, when n = 3, then K > 107, where n is the number of molecules of chelating agent per heavy metal ion and where K is = (MLn) / (M) (L) ny (MLn) is the concentration of heavy metal ion complexes / chelating agent, (M) is the concentration of free heavy metal ions and (L) is the concentration of free chelating agents.

3. A process according to claim 1, further characterized in that said chelating agent has a binding constant K to heavy metal ions defined as follows, or mixtures of the ism: when n = l, then K > 5.105, when n = 2, then K > 5.106, when n = 3, then K > 5.107, where n is the number of molecules of heavy metal chelating agent and where K is = (MLn) / (M) (L) ny (MLn) is the concentration of heavy metal ion complexes / chelating agent, (M) is the concentration of free heavy metal ions and (L) is the concentration of free chelating agents.

4. A process according to claim 1, further characterized in that said chelating agent is polycarboxylic acid of pyridine, or salts thereof having one of the following formulas: ")" > wherein R is hydrogen, a halogen atom, a hydroxyl group, an amino group, a carboxyl group or a short chain alkyl group (Ci-Cii) and n is 1 or 2, or mixtures thereof; and preferably it is selected from the group consisting of dipicolinic acid, derivatives thereof, or mixtures thereof.

5. A method according to claim 1, further characterized in that said chelating agent, or mixtures of. same, it is added in amounts of about 0.01% to about 5% by weight of the total composition.

6. A method according to claim 1, further characterized in that said chelating agent, or mixtures thereof, is added in amounts of about 0.01% to about 3% by weight of the total composition.

7. A process according to any of claims 1, 2 or 4, further characterized by a precipitation agent that binds heavy metal ions thus forming salts that have a water solubility product that is not greater than about of 10-6 at a temperature of about 25 ° C, is added to said composition before the separation step.

8. A process according to claim 1, further characterized in that a precipitating agent is added to said composition before said separation step, said precipitating agent being selected from the group consisting of alkali metal oxalate, phosphonate , borate, sesquicarbonate, silicate, carbonate, selenide, vanadate, telluride, thiocarbonate, polonide or mixtures thereof.

9. A process according to claim 1, further characterized in that a precipitating agent is added to said composition before said separation step, said precipitating agent being selected from the group consisting of sodium oxalate, sodium phosphonate, sodium borate, sodium sesquicarbonate, sodium selenide, sodium vanadate, sodium telluride, sodium thiocarbonate, sodium polonide, sodium carbonate or sodium silicate, or mixtures thereof.

10. A method according to claim 8, further characterized in that each precipitating agent present is added in an amount of about 0.01% to about 10% by weight of the total composition.

11. A method according to claim 8, further characterized in that each precipitating agent present is added in an amount of about 0.01% to about 7% by weight of the total composition. 12.- A process according to claims 1 or 8, further characterized in that said composition comprises from about 0.1% to about 10% by weight of the total composition, based on active chlorine, of hipodorito. 13. A process according to claims 1 or 8, further characterized in that said concentrated alkalinity stream is an alkali metal hydroxide, preferably sodium hydroxide, and wherein the pH is from about 11 to about 14. A process according to claims 1 or 8, further characterized in that the more soluble species formed are separated from said composition by filtering said composition with a dewatering filter. 15.- A process for the manufacture of an aqueous liquid bleaching composition having a pH of about 1 to about 14 and comprising from about 0.01% to about 10% by weight of the total composition, based on active chlorine , of hypochlopty, a concentrated source of alkalinity and water, said process including the steps of: mixing said hypochlorite, said concentrated source of alkalinity and said water, adding a precipitating agent selected from the group consisting of alkali metal salts oxalate, foefonato, borate, sesquicarbonate, silicate, carbonate, selenide, vanadate, telluride, thiocarbonate, polonuro or mixtures thereof; each precipitating agent present being preferably added in amounts of from about 0.01% to about 10% by weight of the composition, separating the more soluble species formed from said composition, and then adding a chelating agent having a constant of K binding to ions of heavy metal defined as follows, or mixtures thereof: when n = l, then K > 105, when n = 2, then K > 106, when n = 3, then K > 107, where n is the number of molecules of chelating agent per heavy metal ion and where K is = (MLn) / (M) (L) ny (MLn) is the concentration of heavy metal ion complexes / agent chelator, (M) is the concentration of free heavy metal ions and (L) is the concentration of free chelating agents, preferably in amounts of about 0.01% to about 5% by weight of the total composition.