WO2014086662A1

WO2014086662A1 - Solid glda compositions

Info

Publication number: WO2014086662A1
Application number: PCT/EP2013/075026
Authority: WO
Inventors: Robert Jan MOLL; Kees Bert Geerse
Original assignee: Unilever N.V.; Unilever Plc; CONOPCO, INC., d.b.a UNILEVER
Priority date: 2012-12-03
Filing date: 2013-11-29
Publication date: 2014-06-12

Abstract

This present invention is directed to solid compositions that comprise GLDA and have reduced hygroscopicity as compared to existing GLDA compositions. The invention is based on the discovery that solid materials produced by combining, in an aqueous phase, a GLDA sodium salt and sulfuric acid and subsequently allowing water to evaporate under mild temperatures, have reduced tendency to take up moisture have superiorstability and handling properties and do not require an additional coating. Particulate compositions comprising the GLDA material are provided by the invention, as well as processes for the production thereof. Furthermore, the use of the particulate compositions as builders in detergent products, especially machine dish-washing products is provided.

Description

SOLID GLDA COMPOSITIONS

Field of the Invention

This invention concerns solid compositions comprising GLDA. More in particular, solid compositions are provided comprising a GLDA material with reduced hygroscopicity that does not require a protective coating. Particulate compositions comprising the GLDA material are provided, as well as processes for the production thereof.

Background of the Invention

Detergent formulations typically contain a number of different active components, including builders, surfactants, enzymes and bleaching agents. Builders (complexing agents) are commonly applied in detergent compositions in order to negate the negative effects of calcium and magnesium ions on the removal of soils by detergent compositions. Phosphorous based builders, such as phosphates, have been used for many years in a wide variety of detergent compositions. However, as part of an increasing trend towards environmentally friendly detergent compositions, alternative building agents have been developed and these alternative builders have found their way into commercial detergent products. Glutamic acid diacetic acid (GLDA) is one of these new generation builders. GLDA is a safe and readily biodegradable alternative. It is predominately made from sugar waste material. GLDA is currently thought to have the smallest environmental impact of all strong builders. GLDA has satisfactory properties with regard to eco and human toxicity. In cleaning formulations and under harsh washing conditions, GLDA complexes hard water ions very well and also retains its high chelating value at elevated temperatures more than other chelating agents. GLDA shows good stain removing properties with tea, starch, meat and burnt milk stains. Also the biocidal boosting power is better than the current used boosters NTA or EDTA. A significant disadvantage of GLDA resides in the strongly hygroscopic behavior, causing serious difficulties in the manufacture, storage and handling of solid GLDA compositions. Many attempts have been made and described in the art to produce solid GLDA formulations which have satisfactory storage and handling properties. Solutions presented so far have involved the use of significant amounts of 'ballast materials' and/or the application of cumbersome manufacturing processes.

For instance, WO 201 1/133462 describes particulate compositions comprising an aminocarboxylic builder and sulfate or citrate in ratios of 6:1 to 1 :1. According to WO 201 1/133462 the particles are produced by combining the builder with sulfate or citrate in solution and converting the solution into particles. The sulfate or citrate is typically added as the respective sodium salt. It is furthermore advocated to add an acidifying agent before adding the sulfate or citrate, in case the aminocarboxylic builder is in the form or a salt mixed with alkaline material, so as to establish a final pH of, preferably, 5-8. Only the production of a particulate MGDA composition is exemplified. MGDA and GLDA differ significantly in hygroscopicity and other properties relevant to the storage and handling behaviour of their solid forms. This is illustrated by the invention described in WO201 1/079940, according to which core particles of GLDA and/or (partial) salts thereof are coated with a layer of MGDA, in order to produce a solid composition having sufficiently low hygroscopicity.

US 2012/0252708 teaches to prepare compositions containing a particle of GLDA and/or (partial) salts thereof and a coating. The process comprises the preparation of a solution containing GLDA having a pH of 4-1 1 , when measured as a 1 % solution in water, followed by a drying step and subsequently applying a coating. In the experimental section, the production of a powder is described by acidification of a GLDA solution to a pH of 3 and subsequent spray-drying thereof at a temperature of 150 °C. According to US 2010/0252708 the acidification results in powder with a reduced tendency to take up water. The gist of US 2012/0252708 is to provide the optimal GLDA material for producing coated GLDA particles. According to US 2012/0252708, at a high pH, GLDA is too brittle, making coating very cumbersome. At low pH, due to a low softening point, the materials are sticky, making coating difficult as well. It is an object of this invention to provide a solid GLDA material that has improved storage and/or handling properties, is more convenient to manufacture and/or comprises less ballast material, as compared to the solid GLDA formulations taught in the art.

Summary of the Invention

The present inventors have unexpectedly discovered that this objective can be achieved with a material comprising a combination of highly acidified GLDA and sodium sulfate salts.

In particular, the present invention is based on the discovery that solid materials produced by combining, in an aqueous phase, GLDA sodium salts and sulfuric acid and subsequently allowing water to evaporate under mild temperatures, have reduced tendency to take up moisture and do not require an additional protective coating in order to assure satisfactory storage and handling properties.

Although the inventors do not wish to be bound by any particular theory, it is believed that the drying of the aqueous GLDA - sulfuric acid solutions under mild temperatures allows for the sodium sulfate and GLDA compounds to structure in a particular manner, which results in a morphology that is distinct from that of the prior art materials, produced at a temperature of approximately 150°C. The influence of the processing temperature on the tendency of the resulting material to take up additional water has been demonstrated by the inventors, as described in the experimental part. Analysis of the materials confirmed the distinction in morphologies, the materials of the invention being characterized by the presence of sodium sulfate crystals of such dimensions that they can be visualized by SEM, as is shown in the examples. The presence of these sodium sulfate crystals is believed to be directly related to the improved properties of the materials, e.g. by preventing GLDA from flowing out of the granule when exposed to an environment of high humidity.

The present inventors furthermore discovered that the stability of particles consisting of the GLDA material of this invention or particles comprising, as an outer layer, a GLDA material of this invention can be further optimized by proper adjustment of the size of the particles.

These and other aspects of the invention will be described and illustrated in more detail in the description below and the appending examples.

Definitions

Glutamic-N,N-diacetate is a compound known in the art as a chelating agent and detergent builder. It is generally referred to as GLDA. The term "glutamic-N,N- diacetate" or "GLDA", when used herein without further indication of the degree of neutralization refers to glutamic-N,N-diacetic acid and any (partial) salt thereof.

The term "sodium sulfate compound", when used herein without further specification, refers to any form of sodium sulfate. When in solid composition, this term thus encompassed amorphous as well as crystalline sodium sulfate and it encompasses, in particular, crystalline compounds including sodium sulfate and molecules of crystal water.

The term "particles" as used herein, unless indicated otherwise, refers to a solid material in the form of, for instance, particles, grains or granules.

Whenever a particle size characteristic of a composition is given herein, unless indicated otherwise, it refers to that characteristic on the basis of a weight distribution. In particular, the term 'weight geometric average diameter' is employed herein, which refers to the average major diameter of the particles on the basis of a weight distribution.

Whenever reference is made herein to a water content, unless indicated otherwise, said water content includes unbound (free) as well as bound water.

Whenever a parameter, such as a concentration or a ratio, is said to be less than a certain upper limit it should be understood that in the absence of a specified lower limit the lower limit for said parameter is 0. Whenever an amount or concentration of a component is quantified herein, unless indicated otherwise, the quantified amount or quantified concentration relates to said component per se, even though it may be common practice to add such a component in the form of a solution or of a blend with one or more other ingredients.

It is furthermore to be understood that the verb "to comprise" and its conjugations is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. Finally, reference to an element by the indefinite article "a" or "an" does not exclude the possibility that more than one of the elements is present, unless the context clearly requires that there be one and only one of the elements. The indefinite article "a" or "an" thus usually means "at least one". Detailed Description of the Invention

A first aspect of the invention concerns a solid GLDA material comprising a

combination of a highly acidified GLDA compound and a sodium sulfate compound, wherein the composition has a pH of below 4 (measured at 20°C) when dissolved in water at 1 wt%, said material comprising crystalline sodium sulfate and amorphous GLDA.

As explained herein before, the invention entails materials and compositions obtainable by the acidification of GLDA tetrasodium salt with sulfuric acid in specific relative amounts. These relative amounts are reflected by the final pH of the compositions, as will be understood by those skilled in the art. In accordance with the invention, the material produces a pH value of below 4 when dissolved in water at 1 wt%, at 20°C. In a preferred embodiment said pH value is below 3.75, more preferably below 3.5. It is typically preferred that said value exceeds 2. The aforementioned values represent the resultant pH of a 1 wt.% solution in pure water, as measured at 20°C using standard equipment.

In accordance with the invention, the GLDA compound of the material may comprise non-neutralized GLDA and/or partial GLDA sodium salts. The GLDA compound accordingly can be represented by the general formula H_nNa(4-_n)-GLDA, wherein n represents an average value (and H and Na represent hydrogen an sodium). In a preferred embodiment of the invention n represents a value within the range of 2-4, preferably 2,5-4, more preferably 3-4, most preferably 3,5-4.

The crystalline sodium sulfate compound may contain water molecules within the crystal lattice. As is known by those skilled in the art, sodium sulfate may exist in various hydrated and non-hydrated forms. Typically, the crystalline sodium sulfate compound may comprise up to 10 moles of crystal water per mole of crystalline sodium sulfate, e.g. at least 1 , at least 2, at least 3, at least 4, at least 5, at least 6, at least 7, at least 8 or at least 9 moles of crystal water per mole of crystalline sodium sulfate.

Preferably however the sodium sulfate compound comprises less than 9, less than 8, less than 7, less than 6, less than 5, less than 4, less than 3, less than 2 or less than 1 moles of crystal water per mole of crystalline sodium sulfate. In an embodiment of the invention the crystalline sodium sulfate is substantially anhydrous.

Typically, the GLDA compound of the material is in amorphous form and the sodium sulfate is present in crystalline form. In an embodiment of the invention, the material has a morphology characterized by the presence of sodium sulfate crystals embedded in a matrix of amorphous GLDA. In an embodiment of the invention the material comprises a continuous GLDA matrix and sodium sulfate crystals that can be visualized using standard SEM analysis, which typically means that they have dimensions in the micrometer range. In a preferred embodiment of the invention, sodium sulfate crystals are present in the material having a major diameter of above 1 μηι, more preferably of above 2 μηι, more preferably of above 5 μηι, more preferably of above 10 μηη. In a particularly preferred embodiment, at least 5% of the total volume of the material, more preferably at least 10 %, more preferably at least 20%, most preferably at least 25%, is occupied by discrete sodium sulfate crystals having a major diameter of above 1 μηη. In an even more preferred embodiment of the invention at least 5% of the total volume of the material, more preferably at least 10%, more preferably at least 20%, most preferably at least 25%, is occupied by discrete sodium sulfate crystals having a major diameter of above 5 μηη. This parameter can be determined by visual assessment of the material using standard SEM equipment. According to an embodiment, a material as defined herein before is provided, comprising sodium sulfate crystals, typically being monoclinic or orthorhombic in shape, having a (major) diameter size distribution (volume-weighted), characterized by an average (major) diameter within the range of 1 -50 μηη, more preferably within the range of 1-25 μηη, most preferably within the range of 1 -15 μηη, as determined using XRT visualization.

The solid GLDA material of the invention preferably contains 30-80 wt.% of the GLDA compound and 30-70 wt.% of the sodium sulfate compound, more preferably 40-70 wt% of the GLDA compound and 35-70 wt.% of the sodium sulfate compound, most preferably 45 -65 wt% of the GLDA compound and 35-55 wt.% of the sodium sulfate compound.

In a preferred embodiment of the invention, the ratio of the GLDA compound and the sodium sulfate compound, on a w/w basis, is within the range of 2:1-1 :2, more preferably within the ration of 3:2-2:3 most preferably within the range of 3:2-1 :1.

In a preferred embodiment of the invention, the combination of the GLDA compound and the sulfate compound make up at least 70 wt.% of the material, more preferably at least 80 wt.%, at least 85 wt.%, at least 90 wt.%, at least 95 wt.% or at least 97 wt.%. In a preferred embodiment of the invention, the material essentially consists of the combination of the GLDA compound and the sodium sulfate compound. Minor components that may be present in the composition include water (i.e. other than the sodium sulfate crystal water), sulfuric acid and processing aids.

Typically, the GLDA material of the invention has a water content of less than 30 wt.%, preferably less than 20 wt.%, more preferably less than 10 wt.%. Furthermore, the water activity of the material typically does not exceed 0.5. The water activity of the material may suitably be determined by a Novasina labmaster conditioned Aw measuring device that is set at 25°C and measured until stable.

A particularly preferred embodiment of the present invention concerns a composition comprising solid GLDA particles, said particles comprising a core and optionally one or more surrounding layers, wherein at least one of the core and the one or more surrounding layers comprises the afore-defined solid GLDA material.

As will be understood by those skilled in the art, the low pH GLDA - sulfuric acid solutions that form the starting material for making the compositions of this invention can be processed into particles using conventional drying or coating techniques. Some drying techniques will yield solid particles comprising or consisting of the GLDA material of this invention. Coating techniques can typically be employed to produce a layer of the GLDA material deposited on a core or seeding material.

Hence, in one embodiment of the invention, a composition comprising solid GLDA particles is provided, wherein the particles essentially consist of cores comprising the solid GLDA material. In an embodiment of the invention the solid GLDA particles comprise granules made up of a plurality of agglomerated cores comprising the GLDA material of the invention.

In another embodiment of the invention, a composition comprising solid GLDA particles is provided, wherein the particles comprise a solid core material surrounded by a layer of the solid GLDA material as defined herein. The core material can be an inert particulate material that is merely used as a seeding material. Suitable examples thereof include materials selected from alkali metal sulfates and citrates. In another embodiment of the invention, the core material can be another detergent active component in particulate form. Suitable examples thereof include MGDA, silicates, citrates, percarbonates, phosphonates, polyacrylates and other chelates. Yet, in another embodiment of the invention, the core material can be a particulate GLDA composition that may be the same or different as the GLDA material surrounding said core. As will be understood by those skilled in the art, the surrounding layer of the non- hygroscopic GLDA material of this invention will prevent the core material from taking up water, so that embodiments are envisaged wherein a hygroscopic GLDA material is surrounded by a layer of the solid GLDA material of this invention so as to obtain a satisfactory product. In a preferred embodiment, the core material and the material making up the surrounding layer are employed in a ratio (w/w) within the range of 1 :1-9:1 , more preferably within the ration of 7:3-4:3 most preferably within the range of 4:1-3:2. Apart from the fact that certain particle sizes will be preferable from a practical point of view, the present inventors, as indicated herein before, also observed that the tendency of the particles to take up water can be further optimized by appropriate selection of the particle size and/or shape. Typically, the GLDA particles are spherical or substantially spherical in shape, which is e.g. reflected by an aspect ratio within the range of 0.2-1 .8, more preferably within the range of 0.6-1.4, e.g. about 1. The GLDA particles contained in the compositions of this invention, preferably have a weight geometric average particle diameter within the range of 50-1200 μηη, more preferably within the range of 100-1000 μηη, most preferably within the range of 200-800 μηη, e.g. 500 μηη. The GLDA particles contained in the compositions of this invention, preferably have a weight geometric mean particle diameter within the range of 50-1200 μηη, more preferably within the range of 100-100 μηη, most preferably within the range of 200-800 μηη, e.g. 500 μηη. Preferably the particulate GLDA composition of this invention comprises low levels of fines and coarse particles, in particular less than 10% by weight of the GLDA particles are above 1200 μηη and/or less than 10% by weight of the GLDA particles are below 50 μηη , more preferably less than 10% by weight of the GLDA particles are above 1000 μηη and/or less than 10% by weight of the GLDA particles are below 100 μηη. The particle size average and mean can be determined using a Malvern particle size analyser based on laser diffraction. The GLDA particles of this invention are characterized, as explained before, by a low tendency to take up moisture. Typically, GLDA particles can be produced in

accordance with this invention, which are characterized by a weight increase of less than 6%, more preferably less than 5.5%, more preferably less than 5%, when stored for 2 hours in an environment that is constantly kept at 20°C and 75% relative humidity.

The composition comprising solid GLDA particles as defined herein before may be a semifinished product consisting essentially or entirely of the solid GLDA particles. Such compositions typically will be employed as an ingredient in the manufacture of detergent products. Hence, in accordance with this embodiment a composition as defined herein before is provided comprising at least 50 wt.%, at least 60 wt.%, at least 70 wt.%, at least 80 wt.%, at least 90 wt.%, at least 95 wt.% or at least 99 wt.% of solid GLDA particles. In another embodiment a composition as defined herein before is provided comprising at least 50 wt.%, at least 60 wt.%, at least 70 wt.%, at least 80 wt.%, at least 90 wt.%, at least 95 wt.% or at least 99 wt.% of the GLDA material of this invention.

The compositions defined herein before, in another embodiment, may be a ready-to- use detergent product comprising solid GLDA particles in conjunction with other detergent active components.

Examples of detergent products encompassed by the invention include dishwashing compositions, laundry detergents and hard surface cleaning compositions. Certain ready-to-use detergent compositions, such as a limescale remover, may contain up to 90 wt.% of detergent builder. Hence, in accordance with this embodiment a detergent product as defined herein before is provided comprising up to 90 wt.%, up to 80 wt.%, up to 70 wt.% or up to 60 wt.% of the solid GLDA particles or the solid GLDA material of this invention. Typically the products contain at least 5 wt.%, at least 10 wt.%, at least 15 wt.% or at least 20 wt.% of the solid GLDA particles or the solid GLDA material of this invention.

According to a particularly preferred embodiment, the detergent product is a

dishwashing composition, especially a machine dishwashing composition. Hence, in accordance with this embodiment a detergent product as defined herein before is provided, in the form of a machine dishwashing product comprising 20-60 wt.%, more preferably 25-55 wt.%, most preferably 30-50 wt.% of the solid GLDA particles of this invention. In another embodiment a detergent product as defined herein before is provided, in the form of a machine dishwashing product comprising 5-50 wt.%, more preferably 10-45 wt.%, most preferably 15-40 wt.% of the GLDA material of this invention. Compositions of this invention in the form of dishwashing compositions may typically comprise further detergent active components, e.g. detergent active components selected from the group consisting of nonionic surfactants, enzymes, enzyme- stabilizers, bleaching agents, bleach activator, bleach catalyst, bleach scavengers, polymers, drying aids, silicates, metal care agents, colorants, scents/perfumes, lime soap dispersants, anti-foam, anti-tarnish and anti-corrosion agents. The further detergent active components may also comprise further detergent builders, although in one embodiment of the invention, the dishwashing composition does not comprise appreciable amounts of phosphates. More preferably it is free from phosphates.

Compositions of this invention in the form of ready-to-use detergent products may be in the form of powders, compressed tablets, encapsulated powders, grains, pastilles or sachets. A second aspect of this invention concerns a process of producing a composition comprising solid GLDA particles, said process comprising the consecutive steps of: a) combining a GLDA sodium salt and sulfuric acid in a high water activity phase; and

b) allowing water to evaporate from said phase to produce a precipitate, wherein, during step b), the temperature of the materials is kept below 107°C.

As mentioned herein before, it is an essential aspect of the invention that, during step b), the temperature of the materials is kept below a certain maximum. Without wishing to be bound by any theory, the inventors hypothesize that this temperature greatly affects the morphology of the sodium sulfate crystals and amorphous GLDA in the material of the invention. It is preferred to carry out step b) under operating conditions that result in a temperature of the materials not exceeding 107°C. Preferably, during step b), the temperature of the materials will not exceed 70°C, more preferably it will not exceed 70 °C, still more preferably it will not exceed 50°C. In a preferred embodiment of the invention the temperature of the materials of the aqueous phase reaches a temperature in excess of 25°C, more preferably a temperature of 32°C. How to accomplish this exactly will depend on the technique and equipment employed to perform step b). Those of average skill in the art will be able to determine appropriate operating conditions and equipment settings to accomplish the desired effect. For example, in a low throughput process, wherein the particles remain inside the equipment for a relatively long time (in the order of minutes), the operating temperature should typically not exceed the maximum temperature defined above, as the material may heat up to that temperature. In a high throughput process, the temperature in the equipment may be significantly higher, e.g. up to 300°C, without the materials heating up to the indicated maximum temperatures, provided the retention time is short enough. Nevertheless, the present inventors established that processes involving 'slow drying', i.e. using low temperatures and relatively long retention times, give particularly good results and are thus preferable. In one particularly preferred embodiment of the invention, a fluid-bed drying process is used with a powder bed temperature of 30- 85°C, preferably 30-70°C, more preferably 35-65°C, and a retention time of more than 5 minutes, preferably more than 10 minutes, most preferably more than 20 minutes. In accordance with the invention, a first embodiment of the process is envisaged wherein step a) comprises consecutive steps of:

a1 ) providing solid GLDA particles comprising a GLDA sodium salt in highly

neutralized form; and

a2) applying on the surface of these particles an aqueous sulfuric acid solution.

In accordance with this embodiment of the invention, during step a2) an aqueous phase will be produced on the surface of the GLDA particles comprising dissolved sulfuric acid and GLDA salt, thus allowing for the exchange of protons and sodium ions between the sulfuric acid and GLDA salt. Removal of water under mild temperatures during step b) yields particles wherein the inner region still contains the highly hygroscopic highly neutralized GLDA sodium salt, while the surrounding region comprises a GLDA and sulfate containing precipitate that has a significantly reduced tendency to take up moisture and thus inhibits moisture uptake by the hygroscopic core material.

As will be appreciated by those skilled in the art, one particularly convenient way to perform the process according to this embodiment of the invention, will be to a1 ) produce a fluidized bed of solid GLDA particles, a2) spray an aqueous sulfuric acid solution on the fluidized bed of GLDA particles, and b) maintain the particles in the fluidized bed for a time sufficient to evaporate the water from the particle surfaces and produce the precipitate. In accordance with this embodiment of the invention, the starting material preferably is the highly neutralized GLDA, preferably a GLDA salt having the formula H_nNa(4_-n)- GLDA, wherein n represents an average value and is 1 or less. Most preferably, the starting material is the GLDA tetrasodium salt. Solid highly neutralized GLDA particles are commercially available, e.g. as Dissolvine GL-74. It is, furthermore, within the routine capabilities of those skilled in the art to produce particulate compositions having a preferred particle size distribution starting from a GLDA solution, such as a commercially available liquid GLDA product, e.g. Dissolvine GL-38 or a solution produced by dissolving Dissolvine GL-74. Although the precise concentration of the aqueous sulfuric acid solution is not critical, it is preferable to use a highly concentrated sulfuric acid solution, which may be up to 98% (w/v) sulfuric acid, corresponding to approximately 18 M. In a preferred embodiment of the invention the sulfuric acid concentration is at least 30% (w/v), more preferably at least 50% (w/v), more preferably at least 70 % (w/v), still more preferably at least 80% (w/v). In a preferred embodiment the sulfuric acid concentration is below 95 % (w/v), more preferably below 90 % (w/v).

In a preferred embodiment, the GLDA particles and sulfuric acid are combined in a ratio (w/w) of 3:2 to 2:1 , based on the weight of the sulfuric acid excluding water.

In accordance with the invention, a second embodiment of the process is envisaged, which comprises the consecutive steps of:

a) producing an aqueous solution comprising dissolved GLDA sodium salt and dissolved sulfuric acid; and

b) drying the aqueous phase to produce a precipitate.

Preferably, in accordance with this embodiment, step a) comprises combining GLDA and sulphuric acid in an aqueous liquid, preferably water. GLDA sodium salt is included in the aqueous liquid at a concentration within the range of 10-60% (w/v), more preferably within the range of 20-55 % (w/v), most preferably within the range 22.5- 50% (w/v). Preferably, sulfuric acid is included in the aqueous liquid at a concentration of 2-20% (w/v), more preferably 4-16% (w/v), most preferably 8-12% (w/v) The starting material preferably is the highly neutralized GLDA, preferably a GLDA salt having the formula H_nNa(4_-n)-GLDA, wherein n represents an average value and and is within the range of 0-1. Most preferably, the starting material is the GLDA tetrasodium salt. GLDA tetrasodium salts are commercially available in solid as well as liquid forms, as indicated herein before.

In accordance with the invention, the GLDA sodium salt and sulfuric acid are combined in amounts that produce a GLDA : sulfate ratio within the range of 4/1 -4/5 preferably within the range of 7/3-1/1 , most preferably within the range of 3/2-2/1. Furthermore, the amounts of water, GLDA sodium salt and sulfuric acid are chosen such as to produce a final pH of the aqueous phase within the range of 0.5-3, more preferably within the range of 0.7-2.5, most preferably within the range of 1 -2.

In a first variant of the above defined second embodiment of the process, the aqueous solution is dried so as to produce a precipitate consisting of 'single phase' particulate matter. In this variant, drying of the aqueous solution can be done by any drying method known to the person skilled in the art, for instance by spray-drying or fluid-bed drying. As noted before, during step b), the temperature of the materials should not exceed 107 °C, in order to produce a material having the advantageous characteristics. It will be within the routine capacity of those skilled in the art to determine the proper operating conditions to accomplish this. In a particularly preferred embodiment of the invention, a particulate composition is produced by fluid-bed drying.

Depending on the form of the material after the drying step, further processing steps may be applied, e.g. compacting and/or crushing of the dried material, until it has the desired shape. The step of crushing includes any method whereby the size of the particles is decreased and is intended to include methods like breaking, crushing, or milling. The step of compacting includes, in particular, methods wherein particles are agglomerated by applying an external force. In a preferred embodiment of the invention, the dried material is processed into a granulate.

In an alternative variant of the afore-defined process, the drying step involves producing a precipitate from the aqueous solution on the surface of a core particle. Hence, in this variant, a process is provided as defined herein before, wherein step b) comprises the consecutive steps of:

b1 ) providing core particles; and

b2) applying to the surface of the core particles the aqueous solution produced in step a) and allowing water to evaporate to produce a precipitate on the surface of said core particles.

In principle, the choice of the core particle material is not particularly limited, provided that the material is able to withstand the processing conditions, without affecting the process of GLDA and sulfate compounds precipitating from the solution. In one embodiment, an inert material is used selected from the group consisting of alkali metal sulfates and citrates In another preferred embodiment the core particles comprise or consist of a material that is a detergent active component selected from the group consisting of MGDA, silicates, citrates, percarbonates, phosphonates, polyacrylates and other chelates/polymers. In another preferred embodiment the core particles comprise or consist of a GLDA material, which may be commercially available highly neutralized GLDA solid composition, highly neutralized GLDA particulate compositions obtained by drying commercially available GLDA liquid compositions or GLDA particulate compositions obtained using any one of the methods described here above.

Preferably the core particles are spherical or substantially spherical in shape, which is e.g. reflected by an aspect ratio within the range of 0.6-1.4., more preferably within the range of 0.8-1 .2, e.g. about 1. The core particles, preferably have a weight geometric average particle diameter within the range of 500-15 μηη, more preferably within the range of 400-80 μηη, most preferably within the range of 200-160 μηη, e.g. 180 μηη. The core particles preferably have a weight geometric mean particle diameter within the range of 500-1 δμηη, more preferably within the range of 400-80 μηη, most preferably within the range of 200-160 μηη, e.g. 180 μηη. Preferably less than 10% by weight of the core particles are above 500 μηι and/or less than 10% by weight of the core particles is below 100 μηη , more preferably less than 10% by weight of the GLDA particles are above 400 μηη and/or less than 10% by weight of the GLDA particles are below 60 μηη. In one embodiment, a process is provided wherein step b2) comprises producing a fluidized bed of the core particles and spraying the aqueous phase onto said fluidized bed of the core particles. This may be accomplished using conventional equipment and techniques, familiar to those skilled in the art. The process of the invention may contain additional steps of combining the particles obtained in step b) with other detergent active components and/or processing the particles obtained in step b), typically in combination with other detergent active components, into a ready-to-use detergent product. The process may include a final step of packaging the particles obtained in step b), the combination of particles obtained in step b) with other detergent active components, or the ready-to-use detergent product.

A further aspect of the invention concerns a composition obtainable by the process of the invention, the use of the product obtainable by the process of the invention as a detergent builder and a detergent product comprising the composition obtainable by the process of the invention.

Examples of detergent products encompassed by the invention include dishwashing compositions, laundry detergents and hard surface cleaning compositions. Certain ready-to-use detergent compositions, such as a limescale remover, may contain up to 90 wt.% of detergent builder. Hence, in accordance with this embodiment a detergent product as defined herein before is provided comprising up to 90 wt.%, up to 80 wt.%, up to 70 wt.% or up to 60 wt.% of the solid GLDA particles or the solid GLDA material of this invention. Typically the products contain at least 5 wt.%, at least 10 wt.%, at least 15 wt.% or at least 20 wt.% of the solid GLDA particles or the solid GLDA material of this invention. According to a particularly preferred embodiment, the detergent product is a dishwashing composition, especially a machine dishwashing composition. Hence, in accordance with this embodiment a detergent product as defined herein before is provided, in the form of a machine dishwashing product comprising 20-60 wt.%, more preferably 25-55 wt.%, most preferably 30-50 wt.% of the solid GLDA particles of this invention. In another embodiment a detergent product as defined herein before is provided, in the form of a machine dishwashing product comprising 5- 50 wt.%, more preferably 10-45 wt.%, most preferably 15-40 wt.% of the GLDA material of this invention. According to this embodiment of the invention, detergent compositions in the form of dishwashing compositions may comprise further detergent active components selected from the group of nonionic surfactants, enzymes, enzyme- stabilizers, bleaching agents, bleach activator, bleach catalyst, bleach scavengers, polymers, drying aids, silicates, metal care agents, colorants, scents/perfumes, lime soap dispersants, anti-foam, anti-tarnish and anti-corrosion agents. The detergent compositions may also comprise further detergent builders, although in one particularly preferred embodiment of the invention, the detergent composition does not comprise appreciable amounts of phosphates. More preferably it is free from phosphates.

Detergent products may be in the form of ready-to-use detergent products may be in the form of powders, compressed tablets, encapsulated powders, grains, pastilles or sachets.

Thus, the invention has been described by reference to certain embodiments discussed above. It will be recognized that these embodiments are susceptible to various modifications and alternative forms. The principal features of this invention can be employed in various embodiments without departing from the scope of the invention. In particular, It is contemplated that any feature or embodiment discussed in this specification can be implemented with respect to any of the products, methods, objects, compositions and uses of the invention, and vice versa. Furthermore, those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, numerous equivalents to the specific features described herein. Such equivalents are considered to be within the scope of this invention and are covered by the claims.

All patent and literature references cited in the present specification are hereby incorporated by reference in their entirety. The following examples are offered for illustrative purposes only, and are not intended to limit the scope of the present invention in any way Examples

In these examples, the following materials were used:

Dissolvine GL 47 S, a 47 wt% solution of GLDA tetrasodium salt ex Akzo nobel.

Sulfuric acid 98%, a 98 wt% solution of sulfuric acid ex Merck

Sulfuric acid 37%, a 37 wt% solution of sulfuric acid ex Merck

Sodium sulfate anhydrate granular 99 wt% ex MSM

Example 1 - effect of drying temperature A homogenized aqueous mix of GLDA and sulfuric acid is prepared, having the composition set out in table 1 below.

Table 1 : GLDA-sulfuric acid solution

The aqueous solution is dried by priling the homogenized mix into a heated Tefal frying pan at two different temperatures while making sure the prils do not exceed 0.5 cm in diameter:

1. 120°C for 15 min

2. 70°C for 60 min

After drying, the granules are cooled until ambient. The excicator with a measurement device has been pre-conditioned until the RH is between 70 - 75% at ambient temperature (20-25°C). The Granules are put on a watch glass at an amount of +/- 0.3 gr. in the excicator in duplo. After two hours in the excicator the watch glass with granules are taken out and weighed immediately. Also the condition of the granules and the structure is visual assessed. The results are summarized in table 2 below, the above shows that drying on a lower temperature is beneficial to the structure of the glda granules.

Table 2: Results of weight measurement and visual inspection

The granules produced in accordance with this example, also were assessed using a SEM scanning electron microscope. The assessment by SEM revealed that the materials produced at different drying temperatures had distinct morphologies, as can be seen from comparison of figures 1A-C and 2A-C, which show the SEM images of the material obtained by drying at 70°C and the material obtained by drying at 120°C respectively. The images clearly show that the low temperature process conditions result in sodium sulfate crystals that can be visually detected on SEM images, while the high temperature process conditions do not result in such sodium sulfate crystals.

X-ray diffraction analysis revealed that the chemical make-up of both materials is largely the same, as shown in figures 3A and 3B (showing the spectra of the low and high temperature products respectively). Both materials contain crystalline sodium sulfate and amorphous GLDA in the same relative amounts, despite their being very distinct in terms of morphology, hygroscopicity and stability. Example 2 - Production of particulate composition

In a liquid mixing vessel of 100L, 30L of dissolvine GL47 S and 20L of a 37% sulfuric acid solution were combined and mixed for 15 minutes until a slurry was formed containing some crystals, to this slurry 50L of water was added so that a transparent slurry without crystals was formed.

The slurry was then sprayed onto HDPE petals, fluidized in a Vomatec fluidized bed.

The inlet air temperature was 30-35°C. The powder bed containing the petals was kept constantly at a temperature of 32-34°C. The solution was sprayed with a standard 2 phase nozzle onto the petals in a total amount of 50% of the weight of the petals. The petals were then dried at 32-34°C for about 2 hours.

After drying, the petals were cooled to 15°C and sieved using a 1000 Urn screen. The sieved residue material was tested for water uptake with the dessicator test for 2 hours at 75%, 20° C The water uptake was 4.0%. The structure of the material was not substantially affected in the dessicator test.

Example 3 - Effect of drying temperature and drying time A homogenized aqueous mix of GLDA and sulfuric acid is prepared, having the composition set out in table 3 below.

Table 3: GLDA-sulfuric acid solution

The mix had a pH of about 3 in a 1 % solution (w/w). This mix was sprayed on a GLDA seeding material (Dissolvine PD-S) with a Vomatec fluidized bed dryer operated with the settings summarized in table 4 Table 4: operating parameters

Three products were produced using different temperatures and retention times, as indicated in table 5. These three products were stored in an open tub under ambient conditions (20-25°C/60-70% RH) and measured every day for weight increase, this weight increase being a measure for hygroscopicity. As a reference, untreated

Dissolvine GL-PD-S was subjected to the same test. The results are summarized in table 5. Table 5: drying temperature, retention time and water uptake of the test products

^*1 ) corresponding to an inlet air temperature of about 100°C

*2) corresponding to an inlet air temperature of about 75°C

*3) corresponding to an inlet air temperature of about 35-40°C

The results as summarized in table 5 clearly show that hygroscopicity decreases as the drying temperature decreases (with a corresponding increase in retention time). The same trend was observed with respect to the structural integrity of the products.

Products 2 and 3 have properties that are particularly advantageous for commercial application in accordance with the invention. These findings correlate with the presence of sodium sulphate crystals in the particles that could be visualized by SEM. Based on experimental findings, it is concluded that in order to create the desired size and morphology of the sodium sulphate crystals a 'slow drying' process, using relatively low temperatures and a relatively long retention/drying time (e.g. typically of more than +/- 5 minutes), is preferable.

Claims

1. Solid GLDA material comprising a combination of a highly acidified GLDA

compound and a sodium sulfate compound, wherein the composition has a pH of below 4 (measured at 20°C) when dissolved in water at 1 wt%, said material comprising amorphous GLDA and sodium sulfate crystals having a major diameter of above 1 μηη.

2. Solid GLDA material according to claim 1 , comprising sodium sulfate crystals having a major diameter of above 5 μηη,

3. Solid GLDA material according to claim 1 or 2, wherein the sodium sulfate

crystals have a volume-weighted average major diameter within the range of 1 -50 μηι.

4. Solid GLDA material according to any one of the preceding

claims, wherein the GLDA sodium salt and the sulfate compound make up at least 80 wt.% of the material.

5. Solid GLDA material according to any one of the preceding claims, wherein the ratio of the GLDA compound and the sodium sulfate compound, on a w/w basis, is within the range of 2:1-1 :2

6. Composition comprising solid GLDA particles, said particles comprising a core and optionally one or more surrounding layers, wherein at least one of the core and the one or more surrounding layers comprises a solid GLDA material as defined in any one of claims 1-5.

7. Composition according to claim 6, wherein the particles have weight geometric average particle diameter within the range of 50-1200 μηη.

8. Composition according to claim 6 or 7, wherein the particles comprise a solid non-hygroscopic core material surrounded by a layer of the GLDA material as defined in any one of claims 1-5.

9. Composition according to claim 6 or 7, wherein the particles comprise a core of hygroscopic GLDA material surrounded by a layer of the GLDA material as defined in any one of claims 1-5.

10. Process of producing a solid GLDA composition comprising the consecutive steps of:

a) combining a GLDA sodium salt and sulfuric acid in a high water activity phase; and

b) allowing water to evaporate from said phase to produce a precipitate; characterized in that, during step b), the temperature of the materials is kept below 107°C.

11. Process according to claim 10, wherein during step b) the temperature of the materials is kept below 70°C.

12. Process according to claim 10 or 1 1 , comprising the consecutive steps of

a) producing an aqueous phase comprising dissolved GLDA sodium salt and dissolved sulfuric acid; and

b) drying the aqueous phase to produce a precipitate.

13. Process according to claim 12, wherein step b) comprises the consecutive steps of:

b1 ) providing core particles; and

b2) applying to the surface of the core particles the aqueous phase produced in step a) and allowing water to evaporate to produce a precipitate on the surface of said core particles.

Process according to any one of claims 10-13, wherein step a) comprises dissolving GLDA sodium salt at a concentration of 10-60% (w/v) and sulfuric acid at a concentration of 2-20% (w/v).

15. Product obtainable by the process of any one of claims 10-14.