WO2019121013A1

WO2019121013A1 - Coated solid active oxygen sources, their manufacture, and use

Info

Publication number: WO2019121013A1
Application number: PCT/EP2018/083626
Authority: WO
Inventors: Christoffer ÖDMAN; Paul LIND; Patrick Meyers; Pentti Pekonen
Original assignee: Kemira Oyj
Priority date: 2017-12-20
Filing date: 2018-12-05
Publication date: 2019-06-27

Abstract

The present invention relates to a coated solid active oxygen source comprising at least one layer of a first coating and at least one layer of a second coating, said first coating consisting essentially of inorganic material, and said second coating consisting essentially of organic polymer material, wherein the organic polymer material comprises a vinyl polymer or combination of vinyl polymers selected from polyvinyl alcohol based polymers. The present invention further relates to production thereof, cleaning formulations comprising such, and the use of said cleaning formulation.

Description

COATED SOLID ACTIVE OXYGEN SOURCES. THEIR MANUFACTURE.

AND USE

Field of the invention

The present invention related to coated solid active oxygen sources, their manufacture and use in cleaning formulations.

Background

Cleaning formulations may today contain solid active oxygen sources. Various processes are known for producing solid active oxygen sources. For example, in a typical fluid bed granulation process for manufacturing of e.g. sodium percarbonate particles (SPC), solid seeds are fluidized with air and the granulator is fed with solutions of hydrogen peroxide and soda ash forming droplets that attach to the solid seeds and growing particles of SPC. Water may be simultaneously removed by a drying mechanism.

Flowever, there is a limitation to the use of solid active oxygen sources, as they are reactive with water containing materials. Thus, solid active oxygen sources are today used for solid cleaning formulations as the presence of water in a fluid or semi-fluid formulation would cause reactions and influence the stability of the final formulation. Today no solid bleaching agents are used in liquid detergents due to the lack of long-term stability.

There is a need to provide new types of solid active oxygen source materials that would allow for incorporation in water-containing liquid, semi liquid, or gel-like cleaning formulations with a good stability of the final formulation.

Summary

The present invention has provided a way to produce coated solid active oxygen sources which are stable also when provided in a liquid, semi liquid, gel or gel-like composition, which may comprise water. The provided system of coated solid active oxygen source and liquid, semi-liquid, gel, or gel-like material is stable, also over time. Thus, the present invention may well be used with in the liquid or gel cleaning formulation area. The coated solid active oxygen sources of the present invention are well protected against ambient humidity and have good stability in a final detergent formulation, even in moist, gel or liquid formulations.

Short description of the drawings

Figure 1 shows a SEM image of coated solid active oxygen source particles according to the invention.

Figure 2 shows a SEM image of coated solid active oxygen source particles with non-homogenous coating due to too intensive drying during the manufacture.

Figure 3 show a SEM image of split particle of Figure 1.

Figure 4 show a SEM image of split particle of Figure 2.

Figure 5 show a graph of DSC measurements of coated solid oxygen source particles having: 1 ) just a first coating of sodium sulfate (see the upper curve), 2) additional second coating of partially hydrolyzed LMW polyvinyl acetate (see the middle curve), and 3) additional second coating of fully hydrolysed VLMW polyvinyl acetate (polyvinyl alcohol) (see the lower curve).

Figure 6 show a graph of pressure measurements of coated solid active oxygen source particles subjected to test liquid containing 5 wt% water using OxiTop measurement. The graph shows release of hydrogen peroxide (pressure of released gases as hectopascals) from the coated solid oxygen source particles over time.

Detailed description

The wording“solution” as used herein is intended to refer to a substantially homogenous mixture of two or more substances; a solid, semisolid, liquid, or gaseous substance is mixed with a liquid.

The wording“emulsion” is intended to refer to a system of two immiscible liquids.

The wording“dispersion” is intended to refer to a system of a dispersed material and a fluid in which it is dispersed.

The wording“suspension” is intended to refer to a dispersion of solid, semisolid, or liquid particles in a fluid. The wordings solution, emulsion, dispersion, and suspension may herein be used interchangeably. For easier reading, the wording solution is herein to be interpreted as encompassing also emulsion, dispersion, and suspension.

As mentioned above the present invention relates to coated solid active oxygen sources, their manufacture and use in cleaning formulations, such as in detergent formulations, including industrial and consumer cleaning formulations.

The coating compositions which are to be applied to the solid active oxygen source cores may comprise mixtures of two or more substances, wherein preferably a solid, semisolid, or liquid material is mixed with a liquid. Thus, the coating compositions to be applied may be in the form of a solution, emulsion, dispersion, or suspension, (which all herein may be referred to as “solution”) when applied to the solid active oxygen source cores.

In one aspect the present invention relates to a coated solid active oxygen source. The solid active oxygen source is a core and it has at least one layer of a first coating consisting essentially of inorganic material, and at least one layer of a second coating consisting essentially of organic polymer material. The at least one layer of the first coating is positioned between the active oxygen source core and at least one layer of the second coating. The solid active oxygen source may be selected from inorganic and/or organic compounds. Preferably the second coating comprises vinyl polymers.

The coated solid active oxygen source is stable also when provided in a liquid, semi-liquid, gel or gel-like compositions. Thus, due to its compatibility in fluid or semifluid systems the coated solid active oxygen sources are suitable for cleaning products. The present coated solid active oxygen source may preferably be introduced in gel or gel-like compositions, which e.g. may be used for cleaning products. The present coated solid active oxygen source is preferably not to be incorporated in solid formulations, e.g. detergents such as laundry detergents. The present coated solid active oxygen source is preferably as mentioned above, to be incorporated into liquid, semi-liquid, gel or gel-like formulations, e.g. fluid or gelatinous detergents. The present coated solid active oxygen source may be produced by the production process comprising the steps of:

providing a solid active oxygen source,

providing at least one layer of a first coating consisting essentially of inorganic material to the solid active oxygen source,

providing at least one layer of a second coating consisting essentially of organic polymer material to the solid active oxygen source provided with the at least one layer of the first coating.

In one embodiment the coated solid active oxygen source is provided by application on a solid active oxygen source at least one layer of a first coating, then application of at least one layer of a second coating, followed by another application of at least one layer of the first coating, and thereafter another application of at least one layer of the second coating.

The present process may further comprise subjecting the solid active oxygen source to an evaporation or dehydration step, herein also referred to as evaporation/dehydration step, during and/or after providing of said first and/or second coating. This step is to evaporate any solvent, such as water, that came into the system when applying the solutions of the inorganic material and the organic polymer material. This solvent or moisture removal step may be performed by heating.

The application of coating compositions and evaporation/dehydration step may be performed by an application and drying process, such as a combined application and evaporation/dehydration process. An application and evaporation/dehydration process may involve equipment selected from the group a multistage drier, drum, spouted bed, fluid bed, and any

combination thereof, preferably a fluid bed is used. In other words, any of these may be used for the providing of the first and/or the second coating.

The temperature when the solid active oxygen source is coated and/or subjected to an evaporation or dehydration step may be in the range of about 50-100°C, such as 70-100°C, 70-95°C, 75-95°C, or 80-90°C.

Air flow used in some processes is a fixed parameter corresponding to lifting i.e. fluidizing, the bed of a fluidized bed. To avoid agglomeration spray rate and temperature can be adjusted. The temperature of the air flow in e.g. a fluid bed is higher than the temperature of the bed itself. If the temperature of a fluidized bed is as disclosed above, i.e. may be in the range of about 50- 100°C, such as 70-100°C, 70-95°C, 75-95°C, or 80-90°C, the temperature of the air flow is higher. The temperature of the air flow may be in the range of about 100-180°C, such as 110-180°C, 120-180°C, 130-180°C, 140-175°C, or 145-170°C. The temperature of the air flow may be lower during and/or after application of the second coating composition compared to during and/or after application of the first coating composition but before the application of the second coating composition, e.g. may be in the range 100-135°C, such as 105-130°C, or 1 10-125°C. The air flow rate used, e.g. in a fluid bed, may be related to the base size of the bed. The base size of the bed (i.e. the area of the base of the bed, the bottom plate) may when divided by the air flow be in the range of about 0.00010-0.00016 nr¹ IT¹ (m²/m³h), such as 0.0001 1 - 0.00015 m ¹h ¹, or 0.00012-0.00014 nr¹lr¹.

The spray feed rate at which the coating compositions may be applied to the core or coated core may be expressed in terms of about 15 g dry solids/h, suitable for example for a bed of 2 kg, to about 400 kg dry solids/h, suitable for example for a bed of 3500 kg. In a fluidized bed such values are dependent on the size of the equipment, wherein a high air flow, and large bed requires a high spray feed rate to provide said coatings on the solid active oxygen source cores, or coated cores.

The spray feed rate at which the coating compositions may be applied to the core or coated core disclosed above may correspond to a spray rate of solution (comprising said dry solids) of about 100 g solution/h to about 1350 kg solution/h.

The spray feed rate may also be expressed independently from e.g. bed size, as the ratio of spray feed time per weight-% of coating material (dry solids) (min/%coating), which may range from about 2 to 100 min/%coating. Preferably the ratio of spray feed time per weight-% of coating material (dry solids) (min/%coating) range from about 1 to 5 min/%coating for the first coating composition containing the inorganic material. Preferably the ratio of spray feed time per weight-% of coating material (dry solids) (min/%coating) range from about 20 to 80 min/%coating for the second coating composition containing the organic polymer material.

The second coating composition containing the organic polymer material forming the second coating may be preheated, before applying, to a temperature of about 70-100°C, such as 80-95°C, 85-95°C, or 85-90°C.

The second coating composition may contain 1 - 20 weight-% of the organic polymer material in an aqueous solution and have a viscosity of about 1 -200 mPas, preferably 1 -100 mPas, more preferably 1 -75 mPas, when heated to a temperature of 70-100°C, as measured using Brookfield DV-II+ viscometer, spindle LV2, 100 rpm.

The solid active oxygen source is provided with at least one layer of a first coating. The first coating may comprise different types of inorganic materials. Said first coating may comprise at least two layers of inorganic materials, different or similar.

The solid active oxygen source is provided with at least one layer of a second coating. The second coating may comprise different types of organic polymer materials, preferably water soluble or swellable polymer materials. Said second coating may comprise at least two layers of said organic polymer materials, wherein the layers may comprise same or different organic polymer materials.

Preferably, the coating composition(s) used to provide the second coating does not contain any inorganic materials. This provides a good control over the barrier function provided. If inorganic materials, e.g. a metal salts, are included in the composition(s) used to provide the second coating defects may arise in the barrier function which provides a deficiency in the desired effect of the materials. It is to be noted that an ionic strength influenced polymer will not behave as expected for the polymer, and the performance thereof will be more difficult to predict. The second coating will also be more difficult to manufacture, and the end-product properties will be different. Inclusion of inorganic materials may influence the product properties of the second coating composition such that a higher viscosity may be obtained making the compositions much more difficult to use in industrial processes requiring the material to be pumped between sections of the process, and/or they may contain higher amounts of water requiring evaporation of more water in the process.

If a batch reactor is used, it creates a single layer. Then several cycles may be needed for increasing the number of layers, and the total coating thickness. If a horizontal reactor is used, it may create multiple layers in one passage. Process-wise it may be more feasible and attractive to create several thin layers to build up the desired coating thickness.

The solid active oxygen source may be selected from the group of intermediate products; crystallisation products; granules; agglomerates; and particles, such as discrete particles; and any combination thereof. Preferably the solid active oxygen source is selected from crystallisation products, granules, and particles, such as discrete particles. The shape of the solid active oxygen source may be of any shape but preferably it is essentially spherical.

The starting material, i.e. the solid active oxygen source cores, may have a bulk density of 0.9 - 1.2 kg/I, such as 1.06-1.16 kg/I, or 1.09-1.12 kg/I.

Preferably the median particle size D50 of the starting material, i.e. the solid active oxygen source cores, is in the range of 300 - 900 pm. The particle size distribution for the solid active oxygen source cores may be inside 0.15 - 1.6 mm, and preferably at the same time median particle size D50 is in the range of 300 - 900 pm. Core particles passing sieve of mesh size 0,15 (mm) are preferably removed as they do not improve the yield, but may unnecessarily increase surface area consuming coating materials. Core particles not passing sieve of mesh size 1 ,6 (mm) are preferably removed as they may increase formation of agglomerates during coating. The D50 and particle size distribution test method uses the sieve analyses on rack of sieves having mesh size (mm) of 0,15; 0,25; 0,425, 0,6; 0,71 ; 1 ,0; 1 ,6

(Retsch) and are based on calculation, alternatively picture modelling with PartAn (video monitor).

The solid active oxygen source cores may be obtained by any known process, such as fluid bed granulation or crystallization. Solid active oxygen source cores, especially sodium percarbonate (SPC) particles, produced in a standard crystallisation process typically have an irregular and jagged shape originating from the crystal structure. Solid active oxygen source cores, especially SPC particles, manufactured by fluid bed granulation may be globular/spherical and may have a dense structure, a smooth surface, and a relatively narrow size distribution, thereby providing smaller surface area and better stability to the solid active oxygen source cores. According to preferred embodiments the solid active oxygen source cores are produced by fluid bed granulation.

Globular or spherical shape, dense structure, smooth surface, and/or relatively narrow size distribution obtainable by fluid bed granulation may provide enhanced stability also to the coated solid active oxygen core as these properties may contribute to the application of coating layers which may be essentially homogeneous and essentially completely encapsulate the core particles. These properties may also further decrease agglomeration tendency during the coating and/or drying.

The present coated solid active oxygen source comprises at least one layer of the first coating on the solid active oxygen source core, and at least one layer of the second coating on the first coating. At least one layer of the first coating may be provided to encapsulate the active oxygen source. At least one layer of the second coating, the outer coating, may be provided to encapsulate the active oxygen source already encapsulated with the at least one layer of the first coating. The solid active oxygen source cores are coated in such a way that agglomeration of the particles is decreased or substantially avoided, the spray picture of the coating media is adapted to the bed movement and the drying capacity in such a way that the coatings are built up on each core without clogging together. Amount of bed material may be adjusted to allow the free movement of the cores to utilize the drying capacity of the coater. When the cores grow, as a consequence of adding more coating material, the bed amount in total may be decreased to ensure that the air flow is sufficient to carry the bed movement at a sufficient level and ensuring that there is enough of moisture removal.

The solid active oxygen source may be any type of solid active oxygen source which is of the type inorganic and/or organic materials. Inorganic solid active oxygen sources may be selected from the group consisting of percarbonates, perborates, persulfate, perchlorates,

hypochlorites, and any combination thereof. It is to be noted that some of the mentioned active oxygen source compounds may in some forms be available as liquids, but herein the present solid active oxygen source is meant to cover forms or species available as solids.

The inorganic solid active oxygen source may be selected from the group consisting of alkali metal salts of percarbonates, perborates, persulfate, perchlorates, and hypochlorites, and any combination thereof. Hypochlorites of alkaline earth metals may also be used, such as calcium hypochlorite. For example, they may be selected from the group consisting of sodium or potassium salts of said percarbonates, perborates, persulfate, perchlorates, hypochlorites, alkaline earth metal hypochlorite, and any combination thereof. The compounds may contain hydrates. Hydrate containing peroxy

compounds may be beneficial as it provides also an increase in alkalinity, which improves the cleaning performance of the compounds. In a preferred embodiment the inorganic solid active oxygen source may comprise sodium percarbonate (SPC). Sodium percarbonate may also be named disodium carbonate, compound with hydrogen peroxide (2:3), sodium carbonate- hydrogen peroxide (2/3), or sodium carbonate peroxide. Sodium persulfate may also be named disodium peroxodisulfate or sodium peroxydisulfate. Potassium persulfate may also be named dipotassium peroxodisulfate or potassium peroxydisulfate. Sodium perborate can also be disclosed as NaB03 · n H20 (n: 1 -4), and may e.g. be selected from sodium perborate monohydrate, and sodium perborate tetrahydrate; preferably sodium perborate tetrahydrate. Potassium perborate can also be disclosed as KB03 · n H20 (n: 0-1 ), and may e.g. be selected from potassium perborate with no hydrate, and potassium perborate monohydrate; preferably potassium perborate monohydrate. Sodium perchlorate can also be disclosed as

NaCI04 · n H20 (n: 0-1 ), and may e.g. be selected from sodium perchlorate with no hydrate, and sodium perchlorate monohydrate. Sodium hypochlorite is preferably used in its pentahydrate from, i.e. as sodium hypochlorite pentahydrate. Organic solid active oxygen sources may comprise for example phtalimido-peroxy-caproic acid (PAP), which also may be named 6- (phthalimido)peroxyhexanoic acid.

Preferably the solid active oxygen source is selected from the group consisting of percarbonates, perborates, persulfate, phtalimido-peroxy- caproic acid (PAP), and any combination thereof; more preferably from the group consisting of percarbonates, phtalimido-peroxy-caproic acid (PAP), and any combination thereof. From a working environment and safety issue point of view, perborates and persulfates may be considered less preferable. Thus, percarbonates, and/or phtalimido-peroxy-caproic acid (PAP) are preferable for the present invention.

In a preferred embodiment the solid active oxygen source cores consist essentially of sodium percarbonate.

The present second coating consists essentially of organic polymer material, preferably of a water soluble or swellable organic polymer material, most preferably water soluble. The water soluble or swellable, preferably water soluble, organic polymer material that may be provided as the second coating may comprise a vinyl polymer or combination of vinyl polymers.

Preferably said organic polymer material consists essentially of the vinyl polymer or combination of vinyl polymers. By a second coating consisting essentially of water soluble or swellable, preferably water soluble, organic polymer material, which consists essentially of combination of vinyl polymers, is meant for example a single layer made of a blend of vinyl polymers, or at least two layers where one of the layers is made of one or more vinyl polymers, and another layer is made of a different vinyl polymer or

combination of vinyl polymers.

The vinyl polymer is preferably selected from polyvinyl alcohol based polymers. As used herein by polyvinyl alcohol based polymers is meant polymers that contain or that are capable of forming pendant alcohol groups. The latter polymers include polyvinyl esters whose pendant ester groups may be readily hydrolyzed into alcohol groups. Examples of polyvinyl esters include polyvinyl acetates, polyvinyl benzoate, polyvinyl butyrate, polyvinyl formate, polyvinyl propionate, polyvinyl stearate, or any combination thereof. Preferred examples of polyvinyl esters include polyvinyl acetates. The polyvinyl alcohol based polymers may also include polyvinyl acetals, which is a family of thermoplastic vinyl resins produced by the condensation of polyvinyl alcohol with an aldehyde. Examples of polyvinyl acetals include polyvinyl acetal, polyvinyl formal, and polyvinyl butyral. Any conditions or methods well known in the art may be used for obtaining the polyvinyl alcohol based polymers. For example, pendant ester groups of polyvinyl esters may be hydrolyzed into pendant alcohol groups by reacting the polyvinyl ester with an alcohol, such as methanol, in the presence of a small amount of an alkali or an acid as a hydrolysis catalyst. In some embodiments the pendant ester groups may be hydrolyzed into alcohol groups before, during, and/or after providing of the second coating, caused by the prevailing conditions. For example, the pendant ester groups may be hydrolyzed into alcohol groups during pretreatment, such as preheating, of the organic polymer material. The hydrolysis may be partial, meaning that only some of the pendant ester groups are hydrolyzed, or full, meaning that all or essentially all ester groups are hydrolyzed into alcohol groups resulting in a polyvinyl alcohol. Preferably the polyvinyl ester is polyvinyl acetate. Copolymers of vinylalcohol and vinylacetate, i.e. poly(vinyl-alcohol-co-vinylacetates) are obtainable by partial hydrolysis of polyvinyl acetate. The polyvinyl alcohol based polymers may be selected from the group of polyvinyl alcohols, polyvinyl esters, partially hydrolyzed polyvinyl esters, and any combination thereof. Preferred polyvinyl alcohol based polymers may be selected from the group consisting of polyvinyl alcohols, polyvinyl acetates, partially hydrolyzed polyvinyl acetates i.e. poly(vinyl-alcohol-co-vinylacetates), and any combination thereof.

Typically, polyvinyl alcohols are manufactured by polymerizing vinyl acetate monomers, and hydrolyzing the formed polyvinyl acetate to obtain polyvinyl alcohols. Even when aiming at full hydrolysis some acetate groups may be present as minor parts or residues on the produced polyvinyl alcohol.

The water soluble or swellable vinyl polymer, such as the polyvinyl alcohol based polymer may also contain minor amounts of other pendant groups than ester and alcohol groups, for example for adjusting the water solubility or swelling behavior, or some other property, such as viscosity, of the polyvinyl alcohol based polymer. Such other pendant groups may be introduced to the polymer backbone by post-derivatization, for example by oxidation, or by incorporation of desired monomers to vinylester monomers when polymerizing the polyvinylester.

The polyvinyl alcohol based polymers may be selected from the group of polyvinyl alcohols, polyvinyl esters, partially hydrolyzed polyvinyl esters, polyvinyl acetals, and any combination thereof; such as selected from the group of polyvinyl alcohols, polyvinyl acetates, partially hydrolyzed polyvinyl acetates, polyvinyl acetals, and any combination thereof. The organic polymer material may comprise a vinyl polymer or combination of vinyl polymers selected from polyvinyl alcohol, polyvinyl acetate, polyvinyl acetal, polyvinyl benzoate, polyvinyl butyral, polyvinyl butyrate, polyvinyl formal, polyvinyl formate, polyvinyl propionate, polyvinyl stearate, or any combination thereof.

The vinyl polymer, preferably the polyvinyl alcohol based polymer, may have a degree of polymerisation of about 100-3000, preferably 150-2500.

The vinyl polymer, preferably the polyvinyl alcohol based polymer, may have a weight average molecular weight of about 10000-200000, preferably 12000-190000. The weight average molecular weight may be determined by gel permeation chromatography.

The vinyl polymer, preferably the polyvinyl alcohol based polymer, may have a number average molecular weight of about 5000-120000, preferably 7000-101000. The number average molecular weight may be determined by gel permeation chromatography.

The vinyl polymer, preferably the polyvinyl alcohol based polymer, may have a pH of about 4-8, preferably 4.5-7.5, such as 5.0 - 6.5.

The vinyl polymer, preferably the polyvinyl alcohol based polymer, may have an acid value of not more than 4, preferably not more than 3.

The vinyl polymer, preferably the polyvinyl alcohol based polymer, may have an ester value of 100 - 180 mg KOH/g, such as 120 - 160 mg KOH/g.

The vinyl polymer, preferably the polyvinyl alcohol based polymer, may have a degree of hydrolysis of at least 75 %, preferably at least 80 %, more preferably at least 85 %, such as 75-100 %, or 80-99%, or 85-98%. The vinyl polymer, such as the polyvinyl alcohol based polymer, may have a viscosity of 1 - 100 mPas, preferably 1 - 10 mPas, such as 4 - 6 mPas, as measured from 4 wt% aqueous polymer solution at 20°C, using a Brookfield DV-II+ viscometer; spindle LV2, 100 rpm.

The following methods may be used for determination of the above parameters.

Acid value

Add 200 ml of water and a stir bar into a 500-ml round-bottom flask, attach a reflux condenser and begin heating in a boiling water bath. Add 10.0 g of the sample and continue heating for 30 min while stirring continuously. Remove the flask from the water bath and continue stirring until the solution reaches room temperature. Quantitatively transfer this solution to a 250-ml volumetric flask and dilute to volume with water. Take 50 ml of the solution, add 1 ml of phenolphthalein TS and titrate with 0.05 M potassium hydroxide until the pink colour persists for 15 sec; record the titre in ml (V). Calculate the acid value, A: A = 5.0(56.1 xVxM)/W, where 56.1 is the formula weight of KOH, M is the molarity of the KOH solution, and W is the weight of sample

(g)·

Ester value

Accurately weigh about 1.0 g of sample into a 250-ml round-bottom flask, add 25 ml 0.5 M alcoholic potassium hydroxide, 25.0 ml of water and a few glass beads. Attach a condenser and allow the contents to reflux for 30 minutes in a boiling water-bath. Let cool to room temperature, remove the condenser, add 1 ml of phenolphthalein TS and titrate immediately with 0.5 M hydrochloric acid; record the titre in ml (V1 ). Carry out a blank test under the same conditions. Titrate with 0.5 M hydrochloric acid and record the titre in ml (V2). Calculate the saponification value, S: S = 56.1 (V2 - V1 ) x M/W, where 56.1 is the formula weight of KOH, M is the molarity of the hydrochloric acid solution, and W is the weight of the sample in (g). Calculate the ester value,

E: E = S - A, where S is the saponification value and A is acid value.

Degree of hydrolysis

Convert the saponification value obtained during the determination of the ester value to the“dried basis” (Sdb): Sdb = (S x 100)/(100 - LOD), where LOD is Loss on Drying. The degree of hydrolysis is: 100 - [7.84 Sdb /(100 - 0.075 Sdb)].

The organic polymer material of the second coating or the second coating composition for applying the second coating, may further contain additives, e.g. polymeric and/or non-polymeric additives, such as plasticizers.

The second coating composition for applying the second coating may further contain other polymers.

If the second coating composition for applying the second coating contains hydrolyzed organic polymer, it may be hydrolyzed in an amount of at least 75 %, preferably at least 80 %, more preferably at least 85 %.

The organic polymer material may have improved adherence to the inorganic material of the first coating, thereby reducing e.g. flaking of the second coating.

The coating compositions used herein are for application onto the solid active oxygen source. The coatings used herein are found on the solid active oxygen source. It is to be noted that the coating compositions in relation to the final coatings comprise higher amount of solvent such as water which may be removed during the present process to provide said coatings. The coating compositions are provided as material mixtures which are to be easy to apply to the solid active oxygen source. After application a coating compositions a coating is formed.

The coatings provided to the active oxygen source may be

homogenous in terms of the coating composition applied to the solid active oxygen source. The coatings provided to the solid active oxygen source may be homogenous in terms of the coverage, or extent of encapsulation, of the coating on the solid active oxygen source. For example, said first coating may be a homogenous coating covering the oxygen source. If more than one layer of the first coating is provided they may individually at least partially cover the solid active oxygen source but together they preferably cover the whole solid active oxygen source, i.e. enclose it. The similar interpretation may be made for the second coating. For example, said second coating may be a

homogenous coating covering the solid active oxygen source having the first coating. If more than one layer of the second coating is provided they may individually at least partially cover the coated solid active oxygen source but together they preferably cover the whole coated active oxygen source, i.e. enclose it.

The homogenous coatings are intended to be interpreted as a single or plurality of layers of the first coating containing the inorganic material or the second coating containing the organic polymer material provided to the solid active oxygen source. The layers may be provided sequentially or

simultaneously. If more than one layer is provided they may not be separable from each other. Thus, they may have the appearance of a single coating.

The coatings provided to the active oxygen source may be made from homogenous materials or combinations of the first and the second coating materials, respectively. The first and second coatings may also be arranged as alternating layers, for example one layer of the first coating, followed by one layer of the second coating, a further layer of the first coating and a further layer of the second coating.

Applying the first coating composition and/or the second coating composition to provide homogeneous layers of the first and/or the second coating may improve the stability of the coated solid active oxygen sources. Also reduced agglomeration during coating may improve the stability of the coated solid active oxygen sources. The physical strength of the coated solid active oxygen sources agglomerated during coating may be inferior, and such agglomerates may easily break during handling, storing, or transportation, thereby revealing only partially coated surface, or even uncoated surface of the solid active oxygen source core. Both homogeneous layer(s) and reduced agglomeration are obtainable by using e.g. fluid bed technologies for the coating. In a preferred embodiment at least one of the layers of the first coating and/or at least one of the layers of the second coating is provided by fluid bed technologies. Preferably all layers of the first coating and/or all layers of the second coating are provided by fluid bed technologies. Most preferably both the first coating and the second coating are provided by fluid bed technologies. For example, the solid active oxygen cores may be coated in a fluid bed with a reactive gas to form e.g. a bicarbonate layer, and simultaneously or subsequently be coated with sodium sulfate forming the layers of the first coating, and thereafter be coated with a second coating composition containing organic polymer material forming the second coating consisting essentially of organic polymer in a fluid bed coater.

The first coating may comprise a water soluble metal salt. Preferably the first coating consists essentially of inorganic material which is a water soluble metal salt. The water soluble metal salt may comprise or be selected from the group consisting of metal sulfates, metal carbonates, metal bicarbonates, metal silicates, or any combination thereof. Alkali metal salts are preferred materials for the inorganic coating. The water soluble alkali metal salts may be selected from the group of alkali metal carbonates, alkali metal bicarbonates, alkali metal sulfates, alkali metal silicates, and any combination thereof. Of the alkali metal salts, preferably sodium and potassium may be used as the metal, providing e.g. sodium or potassium carbonate, bicarbonate, sulfate, silicate, or any combination thereof. Preferred water soluble metal salts are sodium bicarbonate, sodium carbonate, sodium sulfate, sodium silicate (also referred to as waterglass), and any combination thereof.

The first coating may provide desired physical strength and resistance to attrition to the coated solid active oxygen source, thereby reducing dusting during handling and application of the second coating. The first coating may provide improved flowing properties to the solid active oxygen source cores coated with it. Although the first coating comprising the inorganic material may significantly improve the stability of the cores, i.e. the solid active oxygen source, the combination of both the first and the second coatings is necessary for obtaining the stability required e.g. for end-use formulations containing moisture, such as gel-like or liquid detergents.

The inorganic coating consisting essentially of the water soluble metal salts provide an improved stability of the final product. The solid active oxygen source is easily coated with the metal salt and a smooth surface is obtainable. It is believed that the water soluble metal salts, especially sodium bicarbonate, sodium sulfate, sodium silicate, or any combination thereof, are capable of filling in and smoothing surface roughness of the solid active oxygen source core. The cores may have higher or lower surface roughness, depending on e.g. how they were manufactured. For example, SPC core particles obtained by crystallization from aqueous solution may have rough, rugged surface, while fluidized bed granulation process typically provides smooth SPC particles. Smooth surface is beneficial for stability, as the surface area is minimized, and the subsequent layers may be formed with homogenous thickness, which is especially desirable if thin layers are to be provided covering the core. The smoothness may be further improved by controlling the crystallization of e.g. the water-soluble metal salt of the first coating, for example by thermal post-treatment of the coated cores by heating after spraying the first coating composition containing the water-soluble metal salt on the core particles, advantageously with humidity control; by using reactive gas for obtaining the coating; or by incorporating well-known crystal modification agents e.g. in the first coating composition containing the water- soluble metal salt. In preferred embodiments at least part of the water soluble metal salts of the first coating containing inorganic coating are provided using gas phase reactants, because these may be more efficient in surface smoothening as even the smallest notches and grooves are accessible by gas phase reactants. Examples of generation of inorganic sodium salts on wet or moist SPC core particles using gas phase reactants include generation of sodium carbonate and/or sodium bicarbonate layer(s) using CO2, and sodium sulfate layer(s) using SO3.

The solid active oxygen source may first be provided with a first coating, which first coating may be made from a single or multiple layers comprising the same or different inorganic components, and thereafter the second coating may be provided to the coated solid active oxygen source, which second coating may be made from a single or multiple layers comprising the same or different polymer material. The coated solid active oxygen source comprising the first and the second coatings may be further coated with additional coatings. The additional coatings may be applied onto the second coating or any subsequent coatings applied thereon. The additional coatings may comprise same or different materials as the first and the second coatings. The coated solid active oxygen source may be provided by application on a solid active oxygen source at least one layer of a first coating, then application of at least one layer of a second coating, followed by another application of at least one layer of the first coating, and thereafter another application of at least one layer of the second coating.

The first coating provided to the solid active oxygen source may comprise a first layer and a second layer comprising the same or different inorganic components; or the first coating provided to the solid active oxygen source may comprise a mixture of different inorganic components and is provided as a single layer.

The first coating may provide a smoother surface which aids the application of the second coating. As mentioned previously a fluidized bed is preferably used for the production as it assists in the production of preferably round, smooth coated solid active oxygen source cores.

As an example, the solid active oxygen source may comprise a first coating comprising an alkali metal bicarbonate, preferably sodium

bicarbonate, and alkali metal sulfate, preferably sodium sulfate, either as a combination in the layer(s) or as separate layers within the coating; and a second coating comprising the organic polymer material, preferably

comprising polyvinyl alcohol based polymer.

The coatings, in total, may be present in an amount of 2-40% by weight of the total coated solid active oxygen source, such as 3-35 wt%, 4-30 wt%,

5-30 wt%, 6-25 wt%, 7-20 wt%, 9-30 wt%, 9-25 wt%, 9-20 wt%, 9-18 wt%,

10-24 wt%, 12-20 wt%, or 12-18 wt%. Here the amount of the coatings relates to the sum of the first and the second coating provided to the solid active oxygen source.

Said second coating may be present in an amount of 1 -20% by weight of the total coated solid active oxygen source, such as 4.5-15 wt%, 5-12 wt%, or 6-12 wt%.

Said first coating may be present in an amount of 1 -20% by weight of the total coated solid active oxygen source, such as 4.5-15 wt%, 5-12 wt%, or

6-10 wt%.

The second coating may have a coating thickness of 1 -15% of the particle diameter. This may provide a sufficient coverage and protection of the solid active oxygen core, while still having a high enough active content in the final product and sufficiently quick release of the active oxygen. The second coating may have a coating thickness of 6-15%, or 10-15% of the particle diameter. This provides a good coverage and protection of the solid active oxygen core, while still having high enough active content in the final product and good operating window, i.e. active oxygen may be released quickly enough but not too early so that enzyme in the cleaning composition is not deactivated before it has had sufficient time to act on proteinaceous and other stains.

The second coating may have a coating thickness of 5-200 pm. This may provide a sufficient coverage and protection of the solid active oxygen core, while still having high enough active content in the final product and sufficiently quick release of the active oxygen. The second coating may have a coating thickness of 5-150 pm, 7-110 pm, or 35-105 pm. This may provide a good coverage and protection of the solid active oxygen core, while still having high enough active content in the final product and good operating window, i.e. active oxygen is released quickly enough but not too early so that enzyme in the cleaning composition is not deactivated before it has had sufficient time to act on proteinaceous and other stains.

The coated solid active oxygen source may have a median particle size D50 of 0.01 -3 mm, preferably 0.02-2 mm, preferably 0.05-1.6 mm. This median particle size is found beneficial as larger granules may segregate and smaller particles may not be sufficiently covered by the coating, when applying the coating.

The second coating with organic polymer material may further be provided with a plasticizer. The second coating may comprise internal, external and/or secondary plasticizers. The plasticizer may be selected for example from the group consisting of sugars, sugar alcohols, polyethylene glycols (PEGs), urea, glycol, ethylene glycol ether derivatives, propylene glycol, propylene glycol derivatives, butyl glycol, citrates such as triethyl citrate, tributyl citrate, acetyl triethylcitrate, acetyl tributylcitrate, phthalates such as diisobutyl phthalate, dibutyl phthalate, diisoheptyl phtalate,

dibutylphtalate, diethylphtalate or dimethyl phthalate, polyethylene glycerin, sorbitol, dibutyl sebacate, polysorbates, adipates such as di-2- ethylhexyladipate, diisononyl adipate, or diisodecyladipate, trimellitates such as tris-2-ethylhexyl trimellitate, L7,9-trimellitate, or L8,10-trimellitate, phosphates such as tri-2-ethylhexyl phosphate, 2-ethylhexyl diphenyl phosphate, or tricresyl phosphate, and any combination thereof.

The final coated solid active oxygen source may have a

microcalorimeter measurement TAM (Thermal Activity Monitor from

Thermometric AB) value of at most 10 pW/mg, or at most 5 pW/mg, such as below 5 pW/mg, at most 4.8 pW/mg, or at most 4.6 pW/mg, typically at least 1 pW/mg, preferably at least 2 pW/mg, measured over at least 24 h, and at 40^QC. This may be used to show successfully applied coatings onto the solid active oxygen source, indicating for example that the cores were not negatively affected during coating process.

The present invention further relates to a cleaning formulation, such as detergent formulation, including industrial and consumer cleaning

formulations, comprising the present coated solid active oxygen source.

The present invention further relates to a cleaning formulation comprising the present coated solid active oxygen source. The coated solid active oxygen source may be present in an amount of about 5-50 wt% of the cleaning formulation, such as 7-35 wt%, or 10-20 wt%. In one embodiment the moisture content of the cleaning formulation is at most 30 wt%, such as at most 20 wt%, at most 15 wt% water, or at most 10 wt% water. The cleaning formulation may be selected from detergents, such as being selected from the group consisting of gel, gel-like, liquid or semi-liquid detergents, and any combination thereof.

The cleaning formulation may further comprise at least one material selected from:

a) an anionic surfactant and/or a nonionic surfactant;

b) a solvent;

c) water; and

d) optionally one or more materials selected from the group consisting of:

(i) a bleach compatible clay clean polymer;

(ii) a brightener; (iii) a builder;

(iv) a chelant; and

(v) a perfume.

The cleaning formulation may have a neat pH of from 6.5 to 10.5. The cleaning formulation may comprise 0.0001 - 8 % by weight of a detersive enzyme. The detersive enzyme may comprise an enzyme selected from the group consisting of lipase, protease, amylase, cellulase, pectate lyase, xyloglucanase, and any combination thereof.

The bleach compatible clay clean polymer of the cleaning formulation may comprise ethoxylated hexamethylene diamine dimethyl quat,

ethoxysulfated hexamethylene diamine dimethyl quat, or any combination thereof.

The cleaning formulation may be enclosed within a water soluble pouch material, for example within a single compartment pouch or within a multi compartment pouch.

The present coated solid active oxygen source is preferably to be used in liquid or gelatinous systems, such as liquid or gelatinous cleaning formulations. It is preferable that the cleaning formulations not contain any silicate based detergents.

The present invention further relates to use of the cleaning formulation in cleaning or washing of materials selected from the group hard surfaces, textiles, and fabrics.

To further exemplify the invention a more detailed disclosure of embodiments is disclosed below.

As an example, naturally depending on the size of the fluidized bed equipment used, a bed amount of 2 kg may be sufficient for the process and depending on the drying capacity of the coating media the tolerance in deviation may be 100-200 g.

A fluidized bed having a base bed size of about 0.02 m², is provided with an air flow of about 120 m³/h.

As first coating composition, a sodium sulfate solution, may be applied to sodium percarbonate particles. A solution feeding rate of about 4600 g solution/h of readily made coating composition/solution is provided, corresponding to a feeding rate of about 1250 g dry solids/h, and to a ratio of spray feed time per weight-% of coating material (dry solids) of 1

min/%coating. The temperature of the bed was kept at about 90^QC, and the air flow was at about 170^QC.

When applying second coating composition containing fully hydrolyzed very low molecular weight (VLMW, corresponding to a very low solution viscosity) polyvinyl acetate (polyvinyl alcohol / PVOH) adjustment in bed amount seems to be sufficient at a 10 % growth, but for partially hydrolyzed polymer grades of low molecular weight (LMW, corresponding to a low solution viscosity) adjustment may be needed already at 5 % growth or less. This means that for example when providing the second coating of VLMW PVOH to 2 kg of solid active oxygen source coated with the first coating, after applying 0.2 kg of VLMW PVOH on said particles resulting in 10 wt% PVOH coating, 0.2 kg of the PVOH coated particles may need to be withdrawn from the reactor for successfully applying further 0.2 kg of VLMW PVOH, to achieve 20 wt% PVOH coating. But when using the LMW polymer having a bit higher molecular weight and solution viscosity, withdrawal of part of the polymer coated particles may need to be done after applying 0.1 kg (5 wt%) of the LMW polymer for successfully applying further LMW polymer on the particles.

Additionally, the feeding rate can be adjusted to avoid agglomeration.

A feeding rate of 300 g solution/h of readily made second coating

composition/solution, corresponding to a ratio of spray feed time per weight-% of coating material (dry solids) of 27 min/%coating, is possible when the viscosity is fairly low. The feeding rate of second coating material rapidly decrease as the viscosity goes up or when coating material of higher molecular weight is applied. When second coating composition containing partially hydrolyzed organic polymer material is applied the feed rate may be significantly lower starting at about 200 g solution/h, corresponding to a ratio of spray feed time per weight-% of coating material (dry solids) of 40 min/%coating, but shortly decrease to about 100 g solution/h, corresponding to a ratio of spray feed time per weight-% of coating material (dry solids) of 80 min/%coating, or even higher ratio of spray feed time per weight-% of coating material (dry solids).

Readily dissolved solution for coating may be 15 wt% of dry content, when kept preheated to lower the viscosity. Alternatively, it can be lowered to 10 wt% of dry content to keep up the spray speed, but consequently extend the drying time. Especially for grades of partially hydrolyzed organic polymer material of higher molecular weight it is seen as beneficial to lower the dry content of spray solution in attempt not to lower the spray feed too much.

A balance between the different parameters in the coating stage is preferably to be adopted in such a way that in one end agglomeration is substantially avoided as a result of insufficient drying (moist or semi moist particles come in contact with each other and stick together), and in the other end that the coating is not drying on to the surface of the material as the spray droplets start to solidify before hitting it, resulting in porous and bulky material.

Figure 1 is a scanning electron microscope (SEM) image of sample A1 i.e. SPC particles coated with 8 wt% of Na2S04 and 5 wt% of PVOH1 (fully hydrolyzed VLMW PVOH) that has dried on to the granule as a spray film creating a solid and homogenous coating layer, in comparison to Figure 2, which shows sample A2 i.e. SPC particles coated with 8 wt% of Na2S04 and 5 wt% of PVOFI2 (about 90% hydrolyzed LMW polyvinyl acetate) obtained by fluidized bed not having balanced spray picture so that the polymer material has started to solidify already before catching on to the SPC granules, providing a porous and bulky coating as a result.

When evaluating the coating material on split granules it is possible to see the effect of getting the coating material to build up properly on the surface of the granules, with a solid homogenous layer that grows steadily over time, see Figure 3 which is a SEM image of sample A1 , in comparison to the when the coating material starts to solidify already before it is caught on the surface, see Figure 4 which is a SEM image of sample A2, and thus leaving hole formation, cavities, and defects that might reach through the whole layer of coatings added. When applying the coating compositions, the parameters for drying off the water is preferably chosen so that it doesn’t impact on the core granules as such. As the core granule of e.g. SPC has limitation in tolerance to moisture and heat it must be ensured that there is not a decomposition reaction created. The available oxygen level, measured as hydrogen peroxide content, gives a good indication of that the coating has been correctly applied. Verifying the AvOx% (available oxygen %, mass divided by molecular weight of peroxide (H2O2) x molecular weight of oxygen (O), obtained by titration of peroxide) before and after adding the coating layer and deducting the amount of coating added should be a balanced equation.

Correspondingly tracing unbound or free water utilizing

microcalorimeter measurements with a TAM Thermal Activity Monitor from Thermometric AB, showing that the core material stays unharmed after the treatment. It may be with regards of TAM that a slightly lower measurement may be received after coating due to the lower activity in the new coating material. As TAM values of at most 10 pW/mg, or at most 5 pW/mg, is normal for the core granule corresponding values is to be found in the coated material when successfully applied and measured over at least 24 h at 40^QC.

That the coating has been added properly and doesn’t expose the material to elevated risks can be verified with DSC measurements which also support the findings in unchanged TAM values. In Figure 5 there is shown DSC measurements (run from 25 to 130 °C in Al crucible under N2

atmosphere) of reference sample Ref1 (SPC coated with 8 wt% of Na2S04) as the upper curve, of sample B (SPC coated with 8 wt% of Na2S04 and 5 wt% of PVOH2) as middle curve, and of sample C (SPC coated with 8 wt% of Na2S04 and 7.5 wt% of PVOH1 ) as lower curve. As the curves are of similar shape and start to rise at same temperature, at about 1 15 °C, it can be concluded that the coating material or process does not affect the onset temperature of the SPC.

The function of the coatings is to act as a barrier to the surrounding media which is intended to be a liquid or semi-liquid solution with various amounts of water. Physical properties to be successful is to have a

homogenous and solid coating, the both extremes are not sufficient as agglomerates would expose a risk in the fact that there is uneven distribution of coating material especially if agglomerates are broken up. The porous coating has obvious limitations in the fact that there might be openings, holes, pores, and other defects in the coating layer that leaves the core granule completely exposed or with too thin of a layer to have the proper barrier function.

To evaluate this a method using pressure measurements is presented. In closed bottles a mixture of coated solid active oxygen source particles and a test liquid solution (1 ,2- propanediol with varying water content of e.g. 0...15 weight-%) is provided, and a pressure increase is recorded over time due to reaction between the coated particles and the test liquid solution.

Using a pressure devise (OxiTop) to explore the function of the applied coating in a liquid solution of limited water content show that a homogenous and dense coating is beneficial. As the coating material as such is water soluble the amount of water needs to be controlled, but when compared to untreated material of SPC the difference is evident. To stress forward the reaction, the test may be performed at elevated temperature, in this case at 30^QC. With the correct amount and correct application, a coated sample can when tested at elevated temperature at water content below 10 wt% in this type of testing, remain unchanged for a follow-up period of at least 10 days, whereas an uncoated sample of market quality SPC start to react

immediately, and the development in gas production is only depending on granulometry (particle size and dissolution rate).

From Figure 6 it is apparent that a test liquid solution of 1 ,2- propanediol comprising 5 wt% water affect the tested materials very differently. Reference sample Ref1 (SPC coated with 8 wt% of Na2S04) shows immediate impact indicating lowest storage stability in the presence of water, while sample D (SPC coated with 8 wt% of Na2S04 and 7 wt% of PVOFI2) shows improved storage stability. Results for samples E (SPC coated with 9 wt% of Na2S04 and 5 wt% of PVOFI1 , the layers of the first and second coating being organized as follows: 8 wt% Na2S04 layer innermost, followed by 3 wt% PVOFI1 layer, 1 wt% Na2S04 layer, and 2 wt% PVOFI1 layer) and F (SPC coated with 8 wt% of Na2S04 and 1 1 wt% of PVOFI1 ) indicate best storage stability in the presence of water, remaining below 10 hectopascals, sample E even below 5 hectopascals, for a period of over 240 hours / 10 days.

Claims

1. A coated solid active oxygen source comprising at least one layer of a first coating and at least one layer of a second coating, said first coating

consisting essentially of inorganic material, and said second coating consisting essentially of organic polymer material, wherein the organic polymer material comprises a vinyl polymer or combination of vinyl polymers selected from polyvinyl alcohol based polymers.

2. The coated solid active oxygen source according to claim 1 , wherein the solid active oxygen source is selected from the group of percarbonates, perborates, persulfate, perchlorates, hypochlorites, phtalimido-peroxy-caproic acid (PAP), and any combination thereof; preferably from percarbonates.

3. The coated solid active oxygen source according to claim 2, wherein the solid active oxygen source is selected from the group consisting of alkali metal salts of percarbonates, perborates, persulfate, perchlorates,

hypochlorites, and any combination thereof; preferably selected from the group consisting of sodium or potassium salts of said percarbonates, perborates, persulfate, perchlorates, hypochlorites, and any combination thereof; more preferably selected from sodium percarbonate (SPC).

4. The coated solid active oxygen source according to any one of claims 1 -3, wherein the organic polymer material consists essentially of a vinyl polymer or a combination of vinyl polymers.

5. The coated solid active oxygen source according to any one of claims 1 -4, wherein the polyvinyl alcohol based polymers are selected from the group of polyvinyl alcohols, polyvinyl esters, partially hydrolyzed polyvinyl esters, and any combination thereof; preferably selected from the group of polyvinyl alcohols, polyvinyl acetates, partially hydrolyzed polyvinyl acetates, and any combination thereof.

6. The coated solid active oxygen source according to claims 4 or 5, wherein the polyvinyl alcohol based polymer, has at least one feature selected from: a degree of polymerisation of about 100-3000, preferably 150-2500; a weight average molecular weight range of about 10000-200000, preferably 12000-190000;

a number average molecular weight range of about 5000-120000, preferably 7000-101000;

a pH of about 4-8, preferably 4.5-7.5;

an acid value not more than 4, preferably not more than 3;

an ester value of 100 - 180 mg KOH/g, such as 120 - 160 mg KOH/g; a degree of hydrolysis of at least 75 %, preferably at least 80 %, more preferably at least 85 %; and

a viscosity of 1 - 10 mPas, such as 4 - 6 mPas, as measured from 4 wt% polymer solution at 20°C, using Brookfield DV-II+ viscometer, spindle LV2, 100 rpm.

7. The coated solid active oxygen source according to any one of claims 1 -6, wherein the inorganic material comprises a metal salt; preferably comprising metal sulfates, metal carbonates, metal bicarbonates, metal silicates, or any combination thereof; more preferably comprising alkali metal carbonates, alkali metal bicarbonate, alkali metal sulfate, alkali metal silicates, and any combination thereof; more preferably comprising sodium or potassium carbonate, sodium or potassium bicarbonate, sodium or potassium sulfate, sodium or potassium silicate, or any combination thereof; more preferably comprising sodium bicarbonate, sodium carbonate, sodium sulfate, sodium silicate, or any combination thereof.

8. The coated solid active oxygen source according to any one of claims 1 -7, wherein the first and the second coatings, in total, are present in an amount of 2-40% by weight of the total coated solid active oxygen source, preferably 3- 35 wt%, preferably 4-30 wt%, preferably 6-25 wt%, preferably 7-20 wt%, preferably 9-18 wt%.

9. The coated solid active oxygen source according to any one of claims 1 -8, wherein the second coating is present in an amount of 1 -20% by weight of the total coated solid active oxygen source, preferably 4.5-15 wt%, preferably 5-

12 wt%, preferably 6-12 wt%.

10. The coated solid active oxygen source according to any one of claims 1 -9, wherein the first coating is present in an amount of 1 -20% by weight of the total coated solid active oxygen source, preferably 4.5-15 wt%, preferably 5- 12 wt%, preferably 6-10 wt%.

1 1 . The coated solid active oxygen source according to any one of claims 1 -

10, wherein the second coating has a coating thickness of 1 -15% of the particle diameter of the total coated solid active oxygen source, preferably 6- 15%, preferably 10-15%.

12. The coated solid active oxygen source according to any one of claims 1 -

1 1 , wherein the second coating of the total coated solid active oxygen source has a mean coating thickness of 5-200 pm, preferably 5-150 pm, preferably 7-1 10 pm, preferably 35-105 pm.

13. The coated solid active oxygen source according to any one of claims 1 -

12, wherein the total coated solid active oxygen source has a median particle size of 0.01 -3 mm, preferably 0.02-2 mm, preferably 0.05-1 .6 mm.

14. A process for production of a coated solid active oxygen source according to any one of claim 1 -13, comprising the steps of:

providing a solid active oxygen source,

providing to the solid active oxygen source at least one layer of a first coating consisting essentially of inorganic material,

providing to the solid active oxygen source provided with the at least one layer of the first coating, at least one layer of a second coating consisting essentially of organic polymer material, wherein the organic polymer material comprises a vinyl polymer or combination of vinyl polymers selected from polyvinyl alcohol based polymers.

15. The process according to claim 14, further comprising subjecting the solid active oxygen source to an evaporation or dehydration step during and/or after providing of said coatings, preferably by heating.

16. The process according to claim 14 or 15, using at least one apparatus selected from the group a multistage drier, drum, spouted bed, fluid bed, and any combination thereof, preferably fluid bed, for the providing of the first and/or the second coating.

17. The process according to any one of claims 14-16, wherein the second coating is provided by applying a second coating composition containing said organic polymer material, the second coating composition being preheated, before applying, to a temperature of about 70-100°C, preferably 80-95°C, more preferably 85-95°C.

18. The process according to any one of claims 17, wherein the second coating composition contains 1 - 20 wt% of said organic polymer material in an aqueous solution and has a viscosity of about 1 -200 mPas, preferably 1 - 100 mPas, more preferably 1 -75 mPas, when heated to a temperature of 70- 100°C, as measured using Brookfield DV-II+ viscometer, spindle LV2, 100 rpm.

19. A cleaning formulation comprising the coated solid active oxygen source according to any one of claims 1 -13, or the coated solid active oxygen source obtained according to the process of anyone of claims 14-18.

20. The cleaning formulation according to claim 19, comprising the coated solid active oxygen source in an amount of about 5-50 wt% of the cleaning formulation, preferably 7-35 wt%, preferably 10-20 wt%.

21. The cleaning formulation according to claim 19 or 20, wherein the moisture content of the cleaning formulation is at most 30 wt%, preferably at most 20 wt%, more preferably at most 15 wt% water.

22. The cleaning formulation according to any one of claims 19-21 , wherein the cleaning formulation is selected from detergents; preferably selected from the group consisting of gel, gel-like, liquid or semi-liquid detergents, and any combination thereof; more preferably selected from gel, and/or gel-like detergents.

23. The cleaning formulation according to any one of claims 19-22, wherein the cleaning formulation further comprises at least one material selected from: a) an anionic surfactant and/or a nonionic surfactant;

b) a solvent;

c) water; and

d) optionally one or more materials selected from the group consisting of:

(i) a bleach compatible clay clean polymer, preferably comprising ethoxylated hexamethylene diamine dimethyl quat, ethoxysulfated hexamethylene diamine dimethyl quat or any combination thereof;

(ii) a brightener;

(iii) a builder;

(iv) a chelant; and

(v) a perfume.

24. The cleaning formulation according to any one of claims 19-23,

comprising 0.0001 - 8 % by weight of a detersive enzyme, and/or has a neat pH from 6.5 to 10.5.

25. The cleaning formulation according to any one of claims 19-24, wherein the detersive enzyme comprises an enzyme selected from the group consisting of lipase, protease, amylase, cellulase, pectate lyase, xyloglucanase, and any combination thereof.

26. The cleaning formulation according to any one of claims 19-25, wherein the cleaning formulation is enclosed within a water soluble pouch material.

27. Use of the cleaning formulation according to any one of claims 19-26 in cleaning or washing of materials selected from the group of hard surfaces, textiles, and fabrics.