WO2024088902A1

WO2024088902A1 - Opacifier for liquid compositions

Info

Publication number: WO2024088902A1
Application number: PCT/EP2023/079300
Authority: WO
Inventors: Patricia LOPEZ GOMEZ; Luís TALARN MUNTER
Original assignee: Brenntag Holding Gmbh
Priority date: 2022-10-24
Filing date: 2023-10-20
Publication date: 2024-05-02

Abstract

The present invention relates to an opacifier for liquid compositions, which is an aqueous slurry consisting of an alkaline earth metal sulphate (optionally mixed with zeolite, preferably zeolite 4A), a dispersant, and water. The invention also relates to a process for preparing the slurry, to the use of the slurry for opacifying a liquid composition, to a process for opacifying a liquid composition with said slurry, and to opaque liquid compositions comprising the slurry. The invention also relates to a presuspended slurry, additionally comprising a suspending agent, which is useful for preparing the opacified liquid.

Description

“Opacifier for liquid compositions”

Technical field

The present invention relates to the field opacifiers for liquid compositions, in particular, for liquid compositions intended for fabric care, home care, skin care or hair care.

Technical background

Opacifiers are frequent components of liquid laundry and home care detergent compositions, and also are used in many other liquid compositions for hair and skin care, including, for example, shampoos and body washes and gels. Their purpose is to change the appearance of these liquid products from clear to opaque. The “milky” or “lotionized” visual aspect of the opacified liquid compositions is generally better perceived and accepted by consumers.

Opacity is achieved by suspended solid particles within the liquid. Most common opacifiers are based on acrylic polymers, in particular, styrene/acrylate or styrene acrylamide copolymers.

Said acrylic polymer particle suspensions, in general, provide satisfactory opacifying performance. However, their use in consumer products is being now questioned due to their environmental impact because they do not biodegrade, and therefore contribute to the presence of microplastics in the environment.

Microplastics are solid plastic particles, which are found in marine, freshwater and terrestrial ecosystems, as well as in food and drinking water. The origin of the microplastics found in the environment is both the degradation of large pieces of plastic and also those added intentionally in the formulation of consumer products, including detergents and cleaning products. Acrylic-type opacifiers fall into the category of these “intentionally” added microplastics. With the purpose of reducing the amount of microplastics in the environment, there is a decision of the European Comission (25.09.2023) based on a proposal from the European Chemicals Agency (ECHA), an agency of the European Union (EU), to ban microplastic ingredients in consumer products. Therefore, a necessity has arisen to substitute the usual opacifiers based on acrylic polymers with other eco- friendly substances.

Some proposals have been disclosed in the prior art with this purpose.

For example, the international patent application WO-A-2022/094128 relates to an opacified liquid detergent, free of microplastic opacifier, comprising at least one anionic surfactant, a fatty acid, calcium cations and water. It is stated that the calcium cations, in combination with the fatty acid, in a particular weight ratio, form crystals suspended in the liquid components of the detergent composition and give the composition an opacified appearance.

In view of the pressing need for avoiding the use of microplastics, there is the need for providing additional alternatives for substituting microplastic-based opacifiers in liquid compositions. Said alternatives, ideally, should provide effective opacifying effect, not be harmful to the environment, not interfere with the rest of components of the liquid composition, be easily incorporated into the liquid to be opacified, and to form stable suspensions therein.

Object of the invention

The object of the present invention is an aqueous slurry comprising opacifying substances.

Another aspect of the invention is a process for preparing said slurry.

Another aspect of the invention is the use of the slurry for opacifying a liquid composition.

Another aspect of the invention is a process for opacifying a liquid composition. Another aspect of the invention is a pre-suspended slurry, which is suitable for preparing the opacified liquid composition.

Another aspect of the invention is an opaque liquid composition comprising the slurry of the invention.

Detailed description of the invention

The object of the present is an aqueous slurry consisting essentially of an alkaline earth metal sulphate, optionally zeolite, preferably zeolite 4A, a dispersant and water.

The authors of the present invention have developed an opacifying agent, based on an alkaline earth metal sulphate, optionally in combination with zeolite, preferably zeolite 4A, formulated as an aqueous slurry, which is stable, can be easily incorporated into the liquid composition to be opacified, to form stable suspensions, and provides excellent opaque properties to it. Furthermore, the developed opacifier is not based on microplastics and is, therefore, environmentally acceptable.

Along the present description, as well as in the claims, the singular forms, generally preceded by the articles “a,” “an” and “the”, are intended to include the plural forms as well, unless the context clearly indicates otherwise. The ranges defined by the terms "between ... and ..." or by the terms “from ... to... ” are meant to include also said stated endpoints thereof, and they also include any narrower sub-range.

The terms “about” or “approximately” referred to amounts, as used herein, are meant to include the exact amount and also a certain deviation around the stated amount, namely of ±5%.

Unless stated otherwise, the percentages are meant to be by weight (wt%).

The numerical ranges disclosed herein are meant to include any number falling within the ranges and also the lower and upper limits.

The object of the present invention is a composition in the form of an aqueous slurry. The term “slurry”, as is commonly understood, is a fluid made of solids mixed with a liquid, in this case, water.

The main solid components of the slurry are particles of inorganic salts, namely, particles of an alkaline earth metal sulphate, optionally mixed with zeolite, preferably zeolite 4A, particles.

The term “optionally” has herein its common meaning, and it denotes that the opacifying substance of the slurry may be either the alkaline earth metal sulphate alone or a mixture of the alkaline earth metal sulphate and zeolite, preferably zeolite 4A.

The term “zeolite (if present)” as used herein is meant to include both options, i.e., when the slurry contains an alkaline earth metal sulphate and zeolite, preferably zeolite 4A, as opacifying substances, and also when the slurry contains the alkaline earth metal sulphate as the sole opacifying substance, and no zeolite is present.

The terms “consisting essentially of” or “consists essentially of” means that, occasionally, specific further components can be present in the slurry, namely those not materially affecting its essential characteristics, and present in very low concentrations, typically not exceeding 0.5 wt%.

Alternatively, the slurry composition may be defined as “consisting of” and “optionally” including such further component, i.e., that it may or may not include the further component.

In particular, for example, the slurry can occasionally also include an antifoaming agent, also known as defoamer or foam control agent, in order to prevent or reduce the formation of foam during the preparation of the slurry. Anti-foaming agents are well-known in the art. For example, silicones are effective for foam control, and also polypropylene glycols and ethylene oxide-propylene oxide copolymers. These antifoaming agents are widely commercially available from several companies, for example, from Dow. When the slurry contains an anti-foaming agent, it is in an amount generally lower than 0.5 wt%, for example, comprised between 0.001 wt% and 0.5 wt%, typically comprised between 0.01 wt% and 0.1 wt%.

In an embodiment, the slurry of the invention additionally contains an antifoaming agent, preferably in an amount comprised between 0.001 wt% and 0.5 wt%.

The alkaline earth metal sulphate can be selected from calcium sulphate, barium sulphate, strontium sulphate, and mixtures thereof, preferably is selected from calcium sulphate, barium sulphate, and mixtures thereof.

In an embodiment, the alkaline earth metal sulphate is calcium sulphate.

In an embodiment, the alkaline earth metal sulphate is barium sulphate.

The term “alkaline earth metal sulphate” as used herein is meant to include also hydrated forms. Analogously, the terms “calcium sulphate”, “barium sulphate”, and “strontium sulphate” as used herein are meant to also include the hydrated forms.

Alkaline earth metal sulphates are white solids, which are widely available from different commercial sources. They are available in anhydrous form and some of them are also available as different hydrates. For example, calcium sulphate is available also as dihydrate or hemihydrate.

The alkaline earth metal sulphate used in the opacifier slurry, according to the present invention, is typically in the form of fine powder, for example, having an average particle size (D50) comprised between about 0.5 and about 4 micrometres, and/or D90 comprised between about 5 and 10 micrometres, determined by laser diffraction technology, as disclosed, for example, in Horiba Scientific, A guidebook to particle size analysis, 2014, Irvine (USA).

Alkaline earth metal sulphates are widely available from various commercial sources, such as, for example, Alquera (Spain), Altichem (France) or Venator (UK). The slurry optionally comprises also zeolite, preferably zeolite 4A.

Zeolites, as is well-known in the art, are crystalline microporous hydrated aluminosilicates of alkali and alkaline earth metals, which are used in different fields of the technology such as organic synthesis, ion exchange, catalysis, gas separation, building materials, soil treatment, as disclosed, for example, in R. W. Broach, Zeolite Types and Structures, in Zeolites in Industrial Separation and Catalysis. Edited by S. Kulprathipanja, 2010, Wiley, Weinheim [ISBN: 978-3-527-32505-4], pages 27 - 59, and in particular in detergents, as disclosed in Sekhon et al., Detergents - Zeolites and Enzymes Excel Cleaning Power, Resonance, August 2004, 35-45.

In the scope of the present disclosure, zeolites of the type A, P, X, AX and Y are suitable for being used as optional component in combination with the alkaline metal earth sulphate.

Zeolite P has usually a calcium binding capacity of at least 150 mg CaO per gram of anhydrous aluminosilicate. A preferred form of the zeolite P has a silicon to aluminium ratio up to 1.15, and preferably above 0.9, with a tetragonally distorted cubic crystal structure. A process of the preparation of zeolite P is disclosed in EP-0384070.

Zeolite X is the name given to synthetic zeolites having the crystal structure of the naturally occurring mineral, faujasite having an SiC>2 /AI2O3 ratio of less than 3. A process of the preparation of zeolite X is disclosed in US5487882.

Zeolite AX is a co-crystallite composed of 80% zeolite X and 20% zeolite A. This zeolite is commercially available, for example, through the company Nokan.

Zeolite Y belongs to the family of aluminosilicate molecular sieves with a faujasite-type structure, which is characterized by the basic formula |(Ca, Mg, Na2 )29 (H2<D)24O |[Al5sSii34O384]. A process of the preparation of zeolite Y is disclosed in US5785944.

Zeolite A has a Si/AI ratio of 1 . Diverse types of Zeolite A are available in the art, depending on the cation equilibrating the overall charge and the pore diameter. Zeolite 3A includes K⁺ as cation and shows a pore diameter of 3 A. Zeolite 5A includes Ca²⁺ as cation and the pore diameter is 5 A. Zeolite 4A is a synthetic sodium zeolite type A, having Na⁺ as cation and a pore diameter of 4 A , whose chemical formula may be represented as Na2<D. AI2O3. 2 SiC>2. nFW, wherein n is typically 4-4.5. Alternatively, the formula of zeolite 4A may be represented as Nai2 (AIO2)i2 (SiC>2)i2 ■ nFW, wherein n is typically 24-27.

Zeolite 4A is widely available from various commercial sources, such as, for example, IQE (Spain).

The zeolite 4A used for preparing the opacifier slurry is typically in the form of a fine powder, for example, having an average particle size (D50) comprised between about 0.5 and about 4 micrometres, and/or D90 comprised between about 5 and 10 micrometres, determined by laser diffraction technology.

In an embodiment, the slurry of the invention comprises zeolite, preferably zeolite 4A, and, therefore, the object of the invention is an aqueous slurry consisting essentially of an alkaline earth metal sulphate, zeolite, preferably zeolite 4A, a dispersant and water.

In an embodiment, the slurry of the invention consists essentially of calcium sulphate, zeolite, preferably zeolite 4A, a dispersant and water.

In an embodiment, the slurry of the invention consists essentially of barium sulphate, zeolite, preferably zeolite 4A, a dispersant and water.

In another embodiment, the slurry of the invention does not comprise zeolite, and, therefore, the object of the invention is an aqueous slurry consisting essentially of an alkaline earth metal sulphate, a dispersant and water.

In an embodiment, the slurry of the invention consists essentially of calcium sulphate, a dispersant and water.

In an embodiment, the slurry of the invention consists essentially of barium sulphate, a dispersant and water. When the slurry comprises zeolite, preferably zeolite 4A, it is typically in an amount of at least 10 wt%, preferably at least 30 wt%, more preferably at least 50 wt%, more preferably at least 60 wt%, and yet more preferably at least 80 wt%, relative to the total weigh of zeolite plus alkaline earth metal sulphate. The weight ratio alkaline earth metal sulphate:zeolite, preferably zeolite 4A, in the slurry is generally comprised between 9:1 and 1 :9, preferably comprised between 8:1 and 1 :8, more preferably comprised between 7:1 and 1 :7, still more preferably comprised between 6:1 and 1 :6, still more preferably comprised between 5:1 and 1 :5, still more preferably comprised between 4:1 and 1 :4, still more preferably comprised between 3:1 and 1 :3, still more preferably comprised between 2.5:1 and 1 :2.5, still more preferably comprised between 2:1 and 1 :2, still more preferably comprised between 1.8:1 and 1 :1.8, still more preferably comprised between 1.6:1 and 1 :1.6, still more preferably comprised between 1.5:1 and 1 :1.5, still more preferably comprised between 1.4:1 and 1 :1.4, still more preferably comprised between 1.3:1 and 1 :1.3, still more preferably comprised between 1.2:1 and 1 :1.2, still more preferably comprised between 1.1 :1 and 1 : 1.1 , and still more preferably is about 1 :1.

In a preferred embodiment, the weight ratio alkaline earth metal sulphate:zeolite, preferably zeolite 4A, in the slurry is comprised between 1 :4 and 1 :6, preferably 1 :5.

In a preferred embodiment, the weight ratio alkaline earth metal sulphate:zeolite, preferably zeolite 4A, in the slurry is comprised between 1 :4 and 1 :6, preferably 1 :5, wherein the alkaline-metal sulphate is barium sulphate.

Typically, the total concentration of the inorganic salts in the slurry, i.e., of the alkaline earth metal sulphate plus zeolite, preferably zeolite 4A, (if present) is comprised between 45 wt% and 85 wt%, preferably comprised between 50 wt% and 80 wt%, more preferably comprised between 55 wt% and 75 wt%, and still more preferably comprised between 60 wt% and 70 wt%, referred to the total weight of the slurry.

In a preferred embodiment, the weight ratio alkaline earth metal sulphate:zeolite, preferably zeolite 4A, in the slurry is comprised between 1 :4 and 1 :6, preferably 1 :5, and the total concentration of the inorganic salts in the slurry is comprised between 55 wt% and 65 wt%, preferably between 57 wt% and 62 wt%, and more preferably between 59 wt% and 61 wt%, referred to the total weight of the slurry.

In a preferred embodiment, the weight ratio alkaline earth metal sulphate:zeolite, preferably zeolite 4A, in the slurry is comprised between 1 :4 and 1 :6, preferably 1 :5, wherein the alkaline-metal sulphate is barium sulphate, and the total concentration of the inorganic salts in the slurry is comprised between 55 wt% and 65 wt%, preferably between 57 wt% and 62 wt%, and more preferably between 59 wt% and 61 wt%, referred to the total weight of the slurry.

The slurry also comprises a dispersing agent or dispersant.

Any suitable substance can be used as dispersing agent, as are well- known in the art. Dispersants, as is well-known, are typically added to mineral slurries for stabilizing the suspended particles, to avoid the aggregation of said particles, and to reduce the viscosity of the slurry, thus allowing for the preparation of stable slurries of high solid content.

The dispersant is used in very small amounts in the slurry, typically, of up to about 1 wt%, for example, in an amount comprised between 0.05 wt% and 1.0 wt%, preferably comprised between 0.1 wt% and 0.8 wt%, more preferably comprised between 0.2 wt% and 0.6 wt%, and still more preferably comprised between 0.3 wt% and 0.5 wt%, referred to the total weight of the slurry. In this way, a stable slurry comprising even more than 60 wt% of solids can be obtained. The stated amounts of dispersant in the slurry relate to the amount active dispersant substance, or dry matter, irrespective that if, for convenience, it can be added to the slurry as a mixture with water, in different concentrations.

Typical dispersants are polymers, for example, polycarboxylic acids, such as homo-polymers and co-polymers of acrylic acid or methacrylic acid, or co-polymers of maleic acid or maleic anhydride with hydrophobic monomers, wherein the acrylic and methacrylic polymers can be partially or completely in the form of their ammonium, alkali metal or alkaline earth metal salts. Suitable examples are, among others, co-polymers of acrylic acid with a monomer selected from maleic acid, maleic anhydride, 2- acrylamido-2-methyl-1-propanesulfonic acid (also known as its acronym AMPS), an alkali salt of AMPS, hydrophobic monomers, and mixtures thereof.

A preferred dispersant is a co-polymer of acrylic acid, further comprising 2-acrylamido-2-methyl-1 -propanesulfonic acid (AMPS), or an alkali metal salt thereof.

For example, a preferred dispersant is an acrylic terpolymer comprising acrylic acid, a N-substituted acrylamide and AMPS, or an alkali metal salt thereof. A particularly preferred acrylic terpolymer comprises the following monomers: acrylic acid, /V-t-butyl acrylamide and sodium 2-acrylamido-2-methyl-1 -propanesulfonate.

Another preferred dispersant is a bipolymer of acrylic acid and 2- acrylamido-2-methyl-1 -propanesulfonic acid (AMPS), or an alkali metal salt thereof.

Another preferred dispersant is a co-polymer of maleic acid or maleic anhydride with an olefine.

Said polymeric dispersants may be optionally blended with a non-ionic surfactant.

In an embodiment, the dispersant is a mixture of a polymer dispersant, as described hereinabove, and a non-ionic surfactant.

According to this embodiment, the dispersant polymer is mixed with a small amount of a non-ionic surfactant. When a non-ionic surfactant is added, the weight ratio polymer:non-ionic surfactant is typically comprised between 2:1 and 20:1 , preferably between 5:1 and 15:1 , more preferably between 7:1 and 13:1 , for example of about 10:1.

The non-ionic surfactant is, for example, an alcoxylated fatty alcohol, preferably, an ethoxylated fatty alcohol, typically, a Cs-C ethoxylated fatty alcohol, either primary or secondary. The ethoxylated fatty alcohol typically comprises from 3 to 10 ethylene oxide units. Furthermore, it can optionally be additionally propoxylated or butoxylated. Examples of suitable ethoxylated fatty alcohols are, for example, an ethoxylated and butoxylated secondary C11-C15 alcohol, an etholylated and propoxylated primary Cs-C alcohol, or an etholylated and propoxylated primary C10-C12 alcohol.

To prepare the slurry, the dispersant is preferably used as pre-prepared aqueous emulsion/dispersion in water, typically comprising about 30-60% of active dispersant substances and the rest of water.

For preparing the slurry, the components, i.e., water, the alkaline earth metal sulphate, zeolite, preferably zeolite 4A, (if present), and the dispersing agent, are thoroughly mixed until obtaining a stable homogeneous slurry. Of course, when the slurry contains an additional component, such as an anti-foaming agent, as discussed above, it is also added and mixed.

The mixing process can be performed according to standard methods, for example, by using a ball mill, a high shear mixer, colloidal mill, or any other device capable of dispersing the particles of the inorganic salts and/or reducing the mean particle size of said materials.

Another aspect of the invention is a process for preparing the aqueous slurry comprising the step of dispersing the alkaline earth metal sulphate, the zeolite, preferably zeolite 4A, (if present) and the dispersing agent in water.

The aqueous slurry, based on alkaline earth metal sulphate and, optionally, zeolite, preferably zeolite 4A, as described above, can be used as opacifier for liquid compositions.

Surprisingly, it was found that liquid compositions comprising the slurry of the invention were perfectly opaque, providing an opacity analogous to that obtained with the microplastic-based commercial opacifier Acusol® OP301 (Dow), comprising styrene/acrylate co-polymer as opacifying substance.

Furthermore, the aqueous slurry of the invention can be easily dispersed into any liquid composition, to provide a stable opaque liquid by simply pouring the slurry into the composition to be opacified and mixing using conventional mixer apparatus, such as paddle mixer.

Therefore, another aspect of the invention is the use of the slurry of the invention for opacifying a liquid composition.

In order to opacify the liquid composition, the slurry of the invention is typically added in an amount comprised between 0.5 wt% and 5 wt%, preferably comprised between 1 wt% and 4 wt%, more preferably comprised between 1.5 wt% and 3.5 wt%, and still more preferably comprised between 2 wt% and 3 wt%, expressed as weight percentage relative to the total weight of the final liquid composition.

Another aspect of the invention is therefore a process for opacifying a liquid composition comprising the step of adding the slurry of the invention to the liquid composition to be opacified, in the proportions as disclosed hereinabove.

In an embodiment, the use of the slurry as opacifier involves adding the aqueous slurry to the liquid to be opacified, together with an auxiliary suspending agent, in order to improve the stability of the final opacified composition.

The auxiliary suspending agent may be any rheology additive providing high viscosity at low shear stress. Usually said additive form three-dimensional networks preventing the sedimentation of pigments and fillers. Among the suspending agents, cellulose polymers, ASE (alkali swellable emulsions) polymers, HASE (hydrophobically modified alkali swellable emulsions) polymers, HEUR (hydrophobically modified polyurethanes), and HMPE (hydrophobically modified polyethers) polymers are well- known in the art.

Preferably, when said auxiliary suspending agent is used, it is a cellulose polymer, preferably provided as an aqueous dispersion, which is readily incorporated into the liquid composition. The cellulose material may be either of plant origin or may be produced by bacterial fermentation, for example, as those supplied by the company CP Kelco. The auxiliary suspending agent is added to the liquid composition in an amount sufficient such as to provide a content of suspending agent in the final opacified liquid typically ranging from 0.01 wt% to 1.0 wt%, preferably ranging from 0.05 wt% to 0.8 wt%, preferably ranging from 0.1 wt% to 0.5 wt%, expressed as percentage of dry suspending agent (e.g., dry cellulose) relative to the total weight of the final opacified liquid composition.

In a particular embodiment, alternatively, said suspending agent can be previously added to the slurry, rather than to the final liquid composition, to prepare a slurry-suspensor mixture, which will referred to herein as “pre-suspended slurry”, which is then added to the liquid composition and thoroughly mixed, to provide the final opacified liquid composition.

According to this particular embodiment, said pre-suspended slurry can be simply prepared by mixing a suitable amount of the slurry of the invention, as described above, with a suitable amount of the suspending agent. The proportion of slurry and suspending agent used to prepare this pre-suspended slurry can be easily calculated based on the required proportion of both components in the final detergent composition, as defined above, and also considering the concentration of the suspending agent (e.g., cellulose) dry matter, when an aqueous dispersion of the suspending agent is used.

Another aspect of the invention is a pre-suspended slurry consisting essentially of an alkaline earth metal sulphate, optionally zeolite, preferably zeolite 4 A, a dispersing agent, a suspending agent, and water; wherein the characteristics of the alkaline earth metal sulphate, zeolite, preferably zeolite 4A, dispersing agent and the suspending agent are as disclosed above.

In a particular embodiment, the pre-suspended slurry consists essentially of an alkaline earth metal sulphate, zeolite, preferably zeolite 4 A, a dispersing agent, a suspending agent, and water; wherein the characteristics of the alkaline earth sulphate, zeolite, preferably zeolite 4A, dispersing agent and the suspending agent are as disclosed above for the slurry. In an embodiment, this pre-suspended slurry consists essentially of about 25-50 wt%, preferably about 30-40 wt% of an alkaline earth metal sulphate, optionally mixed with zeolite, preferably zeolite 4A; about 0.05-1 wt%, preferably about 0.1 -0.5 wt%, of a dispersant; about 1-10 wt%, preferably about 3-6 wt%, of a suspending agent, preferably of cellulose; and water up to the 100 wt%; wherein the characteristics of the alkaline earth sulphate, zeolite, preferably zeolite 4A, dispersing agent and the suspending agent are as disclosed above.

In an embodiment, the pre-suspended slurry does not comprise zeolite.

In an embodiment, the pre-suspended slurry comprises a combination of alkaline earth sulphate and zeolite, preferably zeolite 4A, in the weight ratios disclosed above for the slurry.

In a particular embodiment, the alkaline earth metal sulphate in the presuspended slurry is selected from calcium sulphate, barium sulphate, strontium sulphate, and mixtures thereof, preferably is selected from calcium sulphate, barium sulphate and mixtures thereof.

In an embodiment, the alkaline earth metal sulphate is calcium sulphate.

In an embodiment, the alkaline earth metal sulphate is barium sulphate.

In a preferred embodiment, the weight ratio alkaline earth metal sulphate:zeolite, preferably zeolite 4A, in the pre-suspended slurry is comprised between 1 :4 and 1 :6, preferably 1 :5.

In a preferred embodiment, the weight ratio alkaline earth metal sulphate:zeolite, preferably zeolite 4A, in the pre-suspended slurry is comprised between 1 :4 and 1 :6, preferably 1 :5, wherein the alkaline-metal sulphate is barium sulphate.

The term “opaque” as used herein has its common meaning. An object, in particular, a liquid composition, is considered to be opaque when it does not allow visible light to pass through it and, consequently, objects placed behind the opaque liquid composition cannot be seen. The term opaque is understood as contrary to transparent, as transparent objects allow all light to pass through them and therefore allow to see objects placed behind. However, as used herein, some degrees of opacity are also contemplated, so the term opaque also includes intermediate states between complete opacity and transparency, namely, also includes a translucent appearance in which part of the light, but not all, can pass though the liquid and, therefore, objects placed behind can be discerned but yet not clearly seen.

The opacity of the liquid composition, therefore, can be assessed by simple visual inspection. Furthermore, the degree of opacity can also be determined measuring the turbidity of the opacified liquid, in nephelometric turbidity units (NTU), typically, using a turbidimeter. The turbidimeter operates by measuring light scattering of a sample compared to a reference solution, typically, using a formazin solution as standard. The higher the measured value, the more turbid the solution.

Additionally, or alternatively, for opaque liquids, their opacity may be also indirectly assessed by measuring their lightness using the CIELAB colour scale, based on the colour coordinates (L* a* and b*), wherein the L* value indicates the lightness: an L* value of zero is black while an L* value of 100 is pure white, the a*-axis goes from green (-a*) to red (+a) and the b*-axis goes from blue (-b*) to yellow (+b*).

As shown in the examples, the liquid detergents comprising the opacifier slurry of the invention were completely opaque, analogously to comparative liquid detergents opacified with commercial microplastic-based opacifiers.

Therefore, another aspect of the invention is a liquid composition, typically, an opaque liquid composition, comprising the slurry or the pre-suspended slurry of the invention.

The term “liquid composition”, as used herein, means any liquid composition suitable to be used for skin care, hair care, fabric care or home care.

In a particular embodiment, the liquid composition is a “liquid detergent”, meaning a liquid composition comprising at least one surface-active agent. As used herein, a “liquid detergent” is a liquid composition suitable for cleaning/washing different substrates, including liquid detergents for personal hygiene, such as shampoos, hand soaps, shower gels, or body washes; as well as liquid laundry detergents and liquid hard- surface cleaners for example, for floors, hand dishwashing liquids and liquid degreasers.

The preparation of said liquid detergents is well-known for the skilled in the art.

Typically, the opacified liquid detergent comprises at least one surfactant, and additional components selected from enzymes, builders, co-solvents, hydrotropes, optical whiteners, viscosity adjusters, anti-foaming agents, anti-redeposition agents, antigreying agents, preservatives, dye-transfer inhibitors, colorants, perfumes, among others, and mixtures thereof, as disclosed, for example, in J. J. Garcia Dominguez, Tensioactivos y Detergencia, Editoral Dossat SA, Madrid, 1986. Depending on the enduse of the liquid detergent, different components and/or percentages thereof are selected, as is well-known for the skilled in the art.

The surfactant used in the compositions may be anionic, non-ionic, zwitterionic (or amphoteric), or mixtures thereof, as are well-known in the art, as disclosed, for example, in X. Domingo, A guide to surfactants world, Proa, Barcelona, 1995.

Anionic surfactants, as is well-known, have a negative charge on their hydrophilic end. Suitable anionic surfactants are, for example, linear alkylbenzene sulphonates, alkyl sulphonates, a-olefine sulphonates, alkyl sulphates, fatty alcohol ether sulphates, glycerine ether sulphates, alkyl sulphosuccinates, alkyl phosphates, alky ether phosphates, alkyl phenol and alkyl phenol ether sulphates, fatty acid salts, fatty acid sarcosinates, fatty acid isethionates or fatty acid taurates, among others.

The preferred amount of anionic surfactant in the composition varies depending on the end-use of the liquid detergent. For laundry detergents and hand dishwashing liquids, for example, the amount of anionic surfactant is typically comprised between 5 and 25 wt%, relative to the total weight of the liquid detergent. For hard- surfaces cleaners, the amount used is typically lower, of about 1-5 wt%, relative to the total weight of the liquid detergent. Some examples of suitable non-ionic surfactants are, for example, ethoxylated fatty alcohols, ethoxylated fatty acids, ethoxylated alkylphenols, fatty acid alkanolamides, ethoxylated fatty acid alkanolamides, ethoxylated fatty amines, fatty amine oxides, fatty amidoamine oxides, esters of glycerine and fatty acids, sorbitan and ethoxylated sorbitan esters, sucrose esters, alkyl polyglycosides, ethylene/propylene oxide copolymers, among others.

The amount of non-ionic surfactant also typically varies depending on the end-use of the liquid detergent. For laundry detergents, the preferred amount typically ranges from 5 wt% to 25 wt%. For hand dishwashing liquids the amount typically ranges from 0.5 wt% to 5 wt%. And in hard-surface cleaners, and degreasing agents, the amount typically ranges from about 1 wt% to about 5 wt%, wherein the weight percentages are relative to the total weight of the liquid detergent.

Zwitterionic surfactants are surfactants that carry both a positive and a negative charge. They are typically added to hand dishwashing detergents, in amounts ranging from about 1 wt% to about 5 wt%, relative to the total weight of the liquid detergent, due to their ability to ameliorate skin irritation caused by other surfactants. Some examples of zwitterionic surfactants are alkyl dimethyl betaines, alkylamidobetaines, alkyl and alkylamido sulphobetaines, imidazolinebetaine derivatives and alkylaminopropionates, among others.

Other common ingredients of the liquid detergent are enzymes. Enzymes are typically added for specifically degrading and removing certain type of dirt. Enzymes are typically obtained from microorganism cultures and are used at low concentrations. The most common enzymes used in liquid detergents are proteases, amylases, lipases, cellulases, mananases and pectinases. The enzymes present in liquid detergents generally require stabilizers (glycols, boric acid, phosphonates, calcium chloride, etc...). Enzymes are generally added to laundry liquid detergents, in amounts generally ranging from about 0.2 wt% to about 4 wt%, relative to the total weight of the liquid detergent.

As is well-known, detergent builders being substances that are able to bind cations (mainly calcium, Ca²⁺, and magnesium Mg²⁺) contained in wash solutions, resulting in water softening. Builders are typically incorporated into detergent formulations in order to reduce the negative effect that water hardness causes on detergency. Insoluble calcium or magnesium salts interfere with the effectiveness of the surfactants. Typical builders can be selected from phosphates, carbonates, carboxylates, polycarboxylates (such as polyacrylates or maleic/(meth)acrylic acid copolymers), nitrile triacetic acid (NTA), ethylene diamine tetraacetic acid (EDTA), ethylene diamine disuccinate (EDDS), phosphonates, amino acid derivatives (such as MGDA: Methylglycine /V,/V-diacetic acid), citrates, among others, or mixtures thereof.

The amount of builder in the detergent composition varies depending on the builder selected and the end-use of the composition. For example, amounts ranging from about 0.1 wt% to about 40 wt%, relative to the total weight of the liquid detergent, may be used.

Co-solvents may be incorporated into liquid detergent formulations to help solubilizing active ingredients (especially surfactants) that are in high concentrations. Some suitable co-solvents are, for example, ethanol, isopropyl alcohol, glycerol, ethylene glycol, propylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, dimethyl glutarate, dimethyl adipate, dimethyl succinate or fatty acid esters, among others, or mixtures thereof. Some of them may provide additional effects. For example, alcohols may also act as preservatives, glycols may also act as enzyme stabilizers, or dimethyl esters may provide additional emulsifying capacity.

When a solvent is used, it is typically added in an amount of up to about 10 wt%, relative to the total weight of the liquid detergent.

Hydrotropes may be also added as solubilizing aids of the liquid formulations. Suitable hydrotropes are, for example, sodium or potassium toluene sulphonate; sodium, potassium, calcium, or ammonium xylene sulphonate; or sodium cumene sulphonate. When present in the formulation, they are typically added in amounts ranging from 0.1 to 5 wt%, relative to the total weight of the liquid detergent.

Optical whiteners may also be added to laundry detergents, to make clothes appear whiter and brighter. They are molecules capable of absorbing ultraviolet radiation and re-emitting it in the visible part of the spectrum. In this way, they provide an optical appearance of increased whiteness. Optical brighteners used in detergency have an affinity for fibers of cellulosic origin, such as cotton, depositing on them to exert their optical effect. Suitable optical brighteners are, for example, sulfonated triazolstilbenes, sulfonated biphenylstilbenes, coumarins and imidazolines.

Viscosity adjusters may also be added to the liquid formulations, to achieve a particular preferred viscosity. Suitable viscosity adjusters are, for example, salts (NaCI, MgCh, for example), cellulosic polymers, xanthan gums, acrylic polymers, microgels, layered silicates and organoclays, among others.

When a viscosity adjuster is used, it is typically added in an amount comprised between 0.1 and 5 wt%, relative to the total weight of the liquid detergent.

Liquid detergents occasionally contain anti-foaming agents, for controlling the amount of foam produced by the surface-active agents. Suitable anti-foaming agents are, for example, soaps (which additionally may have builder and emulsifying function), silicones or paraffins, among others.

Liquid detergents usually comprise preservatives to avoid microbiological contamination. Suitable preservatives for liquid detergents are, for example, isothiazolinones, phenoxyethanol, glutaraldehyde, 2-bromo-2-nitropropane-1 ,3-diol (bronopol), essential oils and plant extracts, among others.

Laundry detergents may optionally contain dye-transfer inhibitor polymers, whose function is to block the deposition of dye molecules released (“bleed”) by colored garments onto other garments during laundry. Suitable dye-transfer inhibitor polymers are, for example, polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), polyvinyl Imidazole (PVI), or quaternized starch, among others.

Other possible additives are colorants and perfumes, which have an aesthetic function, to improve appearance and sensory perception of the product; and anti-redeposition and/or anti-greying polymers; or pH adjusters.

The present invention may be defined by the following embodiments:

1 .- An aqueous slurry consisting essentially of an alkaline earth metal sulphate, optionally zeolite, preferably zeolite 4A, a dispersant and water. 2. The slurry according to embodiment 1 , wherein the alkaline earth metal sulphate is selected from calcium sulphate, barium sulphate, strontium sulphate, and mixtures thereof.

3.- The slurry according to embodiment 2, wherein the alkaline earth metal sulphate is selected from calcium sulphate, barium sulphate, and mixtures thereof.

4.- The slurry according to any one of embodiments 1 to 3, wherein it consists essentially of an alkaline earth metal sulphate, a dispersant and water.

5.- The slurry according to embodiment 4, wherein it consists essentially of barium sulphate, a dispersant and water.

6.- The slurry according to any one of embodiments 1 to 3, wherein it consists essentially of an alkaline earth metal sulphate, zeolite, preferably zeolite 4A, a dispersant and water.

7.- The slurry according to embodiment 6, wherein it consists essentially of calcium sulphate, zeolite, preferably zeolite 4A, a dispersant and water.

8.- The slurry according to embodiment 6, wherein it consists essentially of barium sulphate, zeolite, preferably zeolite 4A, a dispersant and water.

9.- The slurry according to any one of embodiments 6 to 8, wherein the weight ratio alkaline earth metal sulphate:zeolite, preferably zeolite 4A, in the slurry is comprised between 9:1 and 1 :9, preferably comprised between 8:1 and 1 :8, more preferably comprised between 7:1 and 1 :7, still more preferably comprised between 6:1 and 1 :6, still more preferably comprised between 5:1 and 1 :5, still more preferably comprised between 4:1 and 1 :4, still more preferably comprised between 3:1 and 1 :3, still more preferably comprised between 2.5:1 and 1 :2.5, still more preferably comprised between 2:1 and 1 :2, still more preferably comprised between 1.8:1 and 1 :1.8, still more preferably comprised between 1.6:1 and 1 :1.6, still more preferably comprised between 1.5:1 and 1 :1.5, still more preferably comprised between 1.4:1 and 1 :1.4, still more preferably comprised between 1.3:1 and 1 :1.3, still more preferably comprised between 1.2:1 and 1 :1.2, still more preferably comprised between 1.1 :1 and 1 : 1.1 , and still more preferably is about 1 :1. 10.- The slurry according to embodiment 9, wherein the weight ratio alkaline earth metal sulphate:zeolite, preferably zeolite 4A, in the slurry is comprised between 1 :4 and 1 :6, preferably 1 :5.

11.- The slurry according to any one of embodiments 1 to 10, wherein the total concentration of alkaline earth metal sulphate plus zeolite, preferably zeolite 4A, (if present) in the slurry is comprised between 45 wt% and 85 wt%, preferably comprised between 50 wt% and 80 wt%, more preferably comprised between 55 wt% and 75 wt%, and still more preferably comprised between 60 wt% and 70 wt%, referred to the total weight of the slurry.

12.- The slurry according to embodiment 11 , wherein the weight ratio alkaline earth metal sulphate:zeolite, preferably zeolite 4A, in the slurry is comprised between 1 :4 and 1 :6, preferably 1 :5 and the total concentration of the inorganic salts in the slurry is comprised between 55 wt% and 65 wt%, preferably between 57 wt% and 62 wt%, and more preferably between 59 wt% and 61 wt%, referred to the total weight of the slurry.

13.- The slurry according to any one of embodiments 10 to 12, wherein the alkaline-metal sulphate is barium sulphate.

14.- The slurry according to any one of embodiments 1 to 13, wherein the concentration of dispersant in the slurry is comprised between 0.05 wt% and 1.0 wt%, preferably comprised between 0.1 wt% and 0.8 wt%, more preferably comprised between 0.2 wt% and 0.6 wt%, and still more preferably comprised between 0.3 wt% and 0.5 wt%, referred to the total weight of the slurry.

15.- The slurry according to anyone of embodiments 1 to 14, wherein the dispersant is a polymer, which is preferably selected from homo-polymers and co-polymers of acrylic acid or methacrylic, co-polymers maleic acid or maleic anhydride with hydrophobic monomers, and mixtures thereof; wherein the acrylic and methacrylic polymers can be partially or completely in the form of their ammonium, alkali metal or alkaline earth metal salts. 16.- The slurry according to embodiment 15, wherein the polymer is a co-polymer of acrylic acid further comprising 2-acrylamido-2-methyl-1 -propanesulfonic acid (AMPS), or an alkali metal salt thereof.

17.- The slurry according to embodiment 15, wherein the polymer is an acrylic terpolymer comprising acrylic acid, an acrylamide and 2-acrylamido-2-methyl-1 -propanesulfonic acid or an alkali metal salt thereof, preferably, the acrylic terpolymer comprises acrylic acid, f-butyl acrylamide, and sodium 2-acrylamido-2-methyl-1 -propanesulfonate.

18.- The slurry according to embodiment 15, wherein the polymer is a bipolymer of acrylic acid and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS), or an alkali metal salt thereof.

19.- The slurry according to embodiment 15, wherein the polymer is a co-polymer of maleic acid or maleic anhydride with an olefine.

20.- The slurry according to any one of embodiments 1 to 14, wherein the dispersant is a mixture of a polymer dispersant as defined in any one of embodiments 15 to 19 and a non-ionic surfactant.

21.- The slurry according to embodiment 20, wherein the non-ionic surfactant is an ethoxylated fatty alcohol, preferably, a C11-C15 ethoxylated fatty alcohol.

22.- The slurry according to embodiments 20 or 21 , wherein the weight ratio polymer:non-ionic surfactant is comprised between 2:1 and 20:1 , preferably comprised between 5:1 and 15:1 , more preferably comprised between 7:1 and 13:1 , and still more preferably is about 10:1.

23.- The slurry according to any one of embodiments 1 to 22, wherein the slurry additionally contains an anti-foaming agent, preferably in an amount comprised between 0.001 wt% and 0.5 wt%.

24.- A process for preparing the slurry according to any one of embodiments 1 to 23 comprising the step of dispersing the alkaline earth metal sulphate, the zeolite, preferably zeolite 4A, (if present), and the dispersing agent in water. 25.- Use of the slurry according to any one of embodiments 1 to 23 for opacifying a liquid composition.

26.- Process for opacifying a liquid composition comprising the step of adding the slurry according to any one of embodiments 1 to 23 to the liquid composition, wherein the slurry is added in an amount comprised between 0.5 wt% and 5 wt%, preferably comprised between 1 wt% and 4 wt%, more preferably comprised between 1.5 wt% and 3.5 wt%, and still more preferably comprised between 2 wt% and 3 wt%, expressed as weight percentage relative to the total weight of the final opacified liquid composition.

27.- Process according to embodiment 26, characterised in that it comprises an additional step of adding a suspending agent to the liquid composition.

28. Process according to embodiment 27, wherein the suspending agent is a cellulose polymer.

29. Process according to embodiments 27 or 28, wherein the suspending agent is added in an amount comprised between 0.01 wt% and 1.0 wt%, preferably comprised between 0.05 wt% and 0.8 wt%, more preferably comprised between 0.1 wt% and 0.5 wt%, expressed as weight of the suspending agent (as dry matter) relative to the total weight of the final opacified liquid composition.

30.- Process according to anyone of embodiments 27 to 29 comprising the following steps: a) combining the slurry of any one of embodiments 1 to 23 with the suspending agent to form and pre-suspended slurry, and b) adding the pre-suspended slurry of step a) to the liquid composition.

31.- Process according to embodiment 30, wherein the pre-suspended slurry of step a) comprises 25-50 wt%, preferably 30-40 wt%, of the alkaline earth metal sulphate plus zeolite, preferably zeolite 4A, (if present); 0.05-1 wt%, preferably 0.1 -0.5 wt%, of dispersant; 1-10 wt%, preferably 3-6 wt%, of suspending agent; and water.

32.- Process according to embodiment 31 , wherein the pre-suspended slurry of step a) consists essentially of 25-50 wt%, preferably 30-40 wt%, of the alkaline earth metal sulphate plus zeolite, preferably zeolite 4A, (if present); 0.05-1 wt%, preferably 0.1 -0.5 wt%, of dispersant; 1-10 wt%, preferably 3-6 wt%, of suspending agent; and water up to the 100 wt%.

33.- Pre-suspended slurry consisting essentially of 25-50 wt%, preferably 30-40 wt%, of an alkaline earth metal sulphate, optionally mixed with zeolite, preferably zeolite 4A; 0.05-1 wt%, preferably 0.1 -0.5 wt%, of a dispersant; 1-10 wt%, preferably 3-6 wt%, of a suspending agent; and water up to the 100 wt%.

34.- Pre-suspended slurry according to embodiment 33, wherein it does not comprise zeolite.

35.- Pre-suspended slurry according to embodiment 33, wherein it comprises zeolite, preferably zeolite 4A.

36.- Pre-suspended slurry according to embodiment 35, wherein the weight ratio alkaline earth metal sulphate:zeolite, preferably zeolite 4A, is comprised between 9:1 and 1 :9, preferably comprised between 8:1 and 1 :8, more preferably comprised between 7:1 and 1 :7, still more preferably comprised between 6:1 and 1 :6, still more preferably comprised between 5:1 and 1 :5, still more preferably comprised between 4:1 and 1 :4, still more preferably comprised between 3:1 and 1 :3, still more preferably comprised between 2.5:1 and 1 :2.5, still more preferably comprised between 2:1 and 1 :2, still more preferably comprised between 1.8:1 and 1 :1.8, still more preferably comprised between 1.6:1 and 1 :1.6, still more preferably comprised between 1.5:1 and 1 :1.5, still more preferably comprised between 1.4:1 and 1 :1.4, still more preferably comprised between 1.3:1 and 1 :1.3, still more preferably comprised between 1.2:1 and 1 :1.2, still more preferably comprised between 1.1 :1 and 1 : 1.1 , and still more preferably is about 1 :1.

37.- Pre-suspended slurry according to embodiment 36, wherein the weight ratio alkaline earth metal sulphate:zeolite, preferably zeolite 4A, is comprised between 1 :4 and 1 :6, preferably 1 :5.

38.- Pre-suspended slurry according to embodiment 37, wherein the alkaline-metal sulphate is barium sulphate. 39.- Pre-suspended slurry according to any one of embodiments 33 to 38, wherein the suspending agent is a cellulose polymer.

40.- Pre-suspended slurry according to any one of embodiments 33 to 39, wherein the dispersant is as defined in any one of embodiments 14 to 22.

41.- Pre-suspended slurry according to any one of embodiments 32 to 39, wherein the alkaline earth metal sulphate is selected from calcium sulphate, barium sulphate, strontium sulphate, and mixtures thereof, preferably is selected from calcium sulphate, barium sulphate, and mixtures thereof, and more preferably is calcium sulphate.

42.- Opaque liquid composition comprising the slurry according to any one of embodiments 1 to 23 or the pre-suspended slurry according to any one of embodiments 33 to 41.

43.- Opaque liquid composition according to embodiment 42, wherein it comprises between 0.5 wt% and 5 wt%, preferably between 1 wt% and 4 wt%, more preferably between 1 .5 wt% and 3.5 wt%, and still more between 2 wt% and 4 wt% of the slurry.

44.- Use according to embodiment 25 or process according to any one of embodiments 26 to 32 or opaque liquid composition according to embodiments 42 or 43, wherein the liquid composition is any liquid composition suitable to be used for skin care, hair care, fabric care or home care, preferably is a liquid detergent composition, and more preferably is selected from a shampoo, a liquid hand soap, a shower gel, a body wash, a liquid laundry detergent, a liquid hard-surface cleaner, a hand dishwashing liquid and a liquid degreaser.

Examples

Example 1.- Preparation of an opacifier slurry according to the invention comprising calcium sulphate and zeolite 4A

A slurry according to the present invention was prepared with the following ingredients:

The dispersant was prepared in advance by mixing 96 wt% of an acrylic acid terpolymer (comprising acrylic acid, sodium AMPS and f-butyl acrylamide as monomers, provided as an aqueous suspension having 43% solids) and 4 wt% of an ethoxylated/butoxylated. secondary C11-C15 alcohol.

The ingredients of the slurry were thoroughly mixed using a high-shear mixer.

Example 2.- Preparation of an opacifier slurry according to the invention comprising barium sulphate

The dispersant used was a co-polymer of acrylic acid.

The ingredients of the slurry were thoroughly mixed using a high-shear mixer.

Example 3.- Preparation of an opacifier slurry according to the invention comprising barium sulphate and zeolite 4A

The ingredients of the slurry were thoroughly mixed using a high-shear mixer.

Example 4.- Preparation of an opacifier slurry according to the invention comprising barium sulphate and zeolite 4A

The ingredients of the slurry were thoroughly mixed using a high-shear mixer.

Example 5.- Preparation of an opaque liquid laundry detergent comprising the opacifier of Example 1

An opacified liquid laundry detergent was prepared with the following ingredients:

The cellulose used was a ready-to-use dispersion in water, comprising 12% dry matter (Cellulon®, CP Kelco). The liquid detergent base used (liquid detergent base_1 ) had the following composition:

Said detergent base was transparent, blue coloured, had a pH value of

7.7 and dry matter content of 23.30%. To prepare the opacified detergent, this detergent base, the cellulose and the slurry were thoroughly mixed using a conventional in a blade mixer. The obtained liquid detergent was blue and completely opaque.

Example 6.- Preparation of an opaque liquid laundry detergent comprising the opacifier of Example 1

Another opacified liquid laundry detergent was prepared with the following ingredients:

The cellulose used was a ready-to-use dispersion in water, comprising

12% dry matter (Cellulon®, CP Kelco).

The base liquid detergent used (liquid detergent base_2) had the following composition:

Said base detergent was transparent, had a pH value of 8.58 and dry matter content of 16%.

To prepare the opacified detergent, the base detergent, the cellulose and the slurry were thoroughly mixed using a conventional in a blade mixer. The obtained liquid detergent was white and completely opaque.

Comparative Example 1.- Preparation of liquid laundry detergent comprising microplastic-based opacifier

An opacified liquid detergent according to the prior art was prepared by mixing 99 wt% of the same base liquid detergent described above in Example 2 (liquid detergent base_1) and 1 wt% of the commercial opacifier Acusol® OP301 , comprising styrene/acrylate co-polymer as opacifying substance.

The obtained opacified detergent was also blue and completely opaque.

Comparative Example 2.- Preparation of liquid laundry detergent comprising microplastic-based opacifier

Another opacified liquid detergent according to the prior art was prepared by mixing 99 wt% of the same base liquid detergent described above in Example 3 (liquid detergent base_2) and 1 wt% of the commercial opacifier Acusol® OP301 , comprising styrene/acrylate co-polymer as opacifying substance. The obtained opacified detergent was also white and completely opaque.

Example 7.- Preparation of an opaque liquid laundry detergent comprising the opacifier of Example 2

The base liquid detergent used (liquid detergent base_2) was the same as disclosed in Example 6.

To prepare the opacified detergent, the base detergent and the slurry were thoroughly mixed using a conventional in a blade mixer. The obtained liquid detergent was white and completely opaque.

Example 8.- Preparation of an opaque liquid laundry detergent comprising the opacifier of Example 4

The cellulose used was a ready-to-use dispersion in water, comprising 12% dry matter (Cellulon®, CP Kelco).

To prepare the opacified detergent, this detergent base, the cellulose and the slurry were thoroughly mixed using a conventional in a blade mixer. The obtained liquid detergent was blue and completely opaque. Example 9.- Preparation of an opaque liquid laundry detergent comprising the opacifier of Example 4

To prepare the opacified detergent, this detergent base, the cellulose and the slurry were thoroughly mixed using a conventional in a blade mixer. The obtained liquid detergent was blue and completely opaque.

Example 10.- Opacity and colour of liquid detergents of Examples 5, 6, 8 and 9 compared to Comparative Examples 1 and 2

No difference was found between the opacity of the liquid detergents opacified with the slurry of the invention (Examples 2 and 3) and the liquid detergents containing microplastic-based opacifiers (Comparative examples 1 and 2), and all of them were completely opaque.

Colour differences between them were determined using the Cl ELAB colour scale. Colour measurements of detergent samples were determined by an X-RITE SP60 Series Sphere Spectrophotometer X-64, using a light source D65 and an observer angle of 10 degrees (D65/10 degrees), and the data was recorder for Specular reflection excluded (SPEX).

10 measurements were made for each tested sample, varying the position of the spectrophotometer in each of them, so that the spectrophotometer was rotated for each measurement up to 360°C. The following table represents the mean values of the 10 measurements for the colour coordinates (L* a* and b*). The L* value indicates the lightness: an L* value of zero is black while an L* value of 100 is pure white. The a*-axis goes from green (-a*) to red (+a) and the b*-axis goes from blue (-b*) to yellow (+b*).

In order to evaluate the effect of the opacifier on the final colour of the opacified liquid detergent, comparison has to be made between the pairs Example 2- Comparative Example 1 and Example 3-Comparative Example 2, as they have the same detergent composition base and only differ in the opacifying system.

The main differences were found in L* value indicating the lightness, with higher values (whiter) for the comparative formulas, compared to the detergents with the mineral opacifier according to the present invention.

That was observable to the naked eye, for example, for blue-coloured liquid detergents of Examples 5 and 8 and Comparative Example 1. The former had a more intense blue colour, while the latter acquired a whitish-blue tone.

Example 11.- Viscosity of liquid detergents of Examples 5 and 6 compared to

Comparative Examples 1 and 2

The viscosity of samples of the liquid detergent compositions, either nonopacified or opacified with the slurry of the invention or with commercial microplasticbased opacifier were measured using a Brookfield viscometer, spindle 2, at 30 or 60 rpm, at 20°C. The results are shown in the table below:

No significative changes were observed in the viscosity of the base formulations after adding the opacifiers.

Claims

1 .- An aqueous slurry consisting essentially of an alkaline earth metal sulphate, optionally zeolite, preferably zeolite 4A, a dispersant and water.

2. The slurry according to claim 1 , wherein the alkaline earth metal sulphate is selected from calcium sulphate, barium sulphate, strontium sulphate, and mixtures thereof; preferably, is selected from calcium sulphate, barium sulphate, and mixtures thereof.

3.- The slurry according to claims 1 or 2, wherein it consists essentially of an alkaline earth metal sulphate, a dispersant and water.

4.- The slurry according to claims 1 or 2, wherein it consists essentially of an alkaline earth metal sulphate, zeolite, preferably zeolite 4A, a dispersant and water; wherein, preferably, the weight ratio alkaline earth metal sulphate:zeolite, preferably zeolite 4A, in the slurry is comprised between 9:1 and 1 :9.

5.- The slurry according to any one of claims 1 to 4, wherein the total concentration of alkaline earth metal sulphate plus zeolite, preferably zeolite 4A, (if present) in the slurry is comprised between 45 wt% and 85 wt%.

6.- The slurry according to any one of claims 1 to 5, wherein the concentration of dispersant in the slurry is comprised between 0.05 wt% and 1.0 wt%, referred to the total weight of the slurry.

7.- The slurry according to anyone of claims 1 to 6, wherein the dispersant is a polymer, which is preferably selected from homo-polymers and co-polymers of acrylic acid or methacrylic, co-polymers maleic acid or maleic anhydride with hydrophobic monomers, and mixtures thereof; wherein the acrylic and methacrylic polymers can be partially or completely in the form of their ammonium, alkali metal or alkaline earth metal salts.

8.- The slurry according to any one of claims 1 to 6, wherein the dispersant is a mixture of a polymer as defined in claim 7 and a non-ionic surfactant; wherein, preferably, the weight ratio polymer: non-ionic surfactant is comprised between 2:1 and 20:1.

9.- A process for preparing the slurry according to any one of claims 1 to 8 comprising the step of dispersing the alkaline earth metal sulphate, the zeolite, preferably zeolite 4A, (if present), and the dispersing agent in water.

10.- Use of the slurry according to any one of claims 1 to 8 for opacifying a liquid composition.

11.- Process for opacifying a liquid composition comprising the step of adding the slurry according to any one of claims 1 to 8 to the liquid composition, wherein the slurry is added in an amount comprised between 0.5 wt% and 5 wt%, preferably comprised between 1 wt% and 4 wt%, more preferably comprised between 1.5 wt% and 3.5 wt%, and still more preferably comprised between 2 wt% and 3 wt%, expressed as weight percentage relative to the total weight of the final opacified liquid composition.

12.- Process according to claim 11 , characterised in that it comprises an additional step of adding a suspending agent to the liquid composition; wherein, preferably, the suspending agent is a cellulose polymer.

13.- Pre-suspended slurry consisting essentially of 25-50 wt%, preferably 30-40 wt%, of an alkaline earth metal sulphate, optionally mixed with zeolite, preferably zeolite 4A; 0.05-1 wt%, preferably 0.1 -0.5 wt%, of a dispersant; 1-10 wt%, preferably 3-6 wt%, of a suspending agent; and water up to the 100 wt%.

14.- Opaque liquid composition comprising the slurry according to any one of claims 1 to 8, or the pre-suspended slurry according to claim 13.

15.- Use according to claim 10, or process according to claims 11 or 12, or opaque liquid composition according to claim 14, wherein the liquid composition is any liquid composition suitable to be used for skin care, hair care, fabric care or home care, preferably is a liquid detergent composition, and more preferably is selected from a shampoo, a liquid hand soap, a shower gel, a body wash, a liquid laundry detergent, a liquid hard-surface cleaner, a hand dishwashing liquid and a liquid degreaser.