Concentrated silicone antifoam emulsion

Abstract

The present invention relates to a concentrated silicone-in-water antifoam emulsion, a preparation process and a process for inhibiting foam.

Description

[0001] Description

[0002] Title: Concentrated silicone antifoam emulsion

[0003] Technical field

[0004] The present invention relates to the field of silicone antifoams. More specifically, the invention relates to a concentrated silicone antifoam emulsion in water, which is easy to handle, dispersible, stable in storage and effective. The present invention also relates to a method for preparing this concentrated low-viscosity antifoam emulsion and a method for inhibiting foam formation using this concentrated antifoam emulsion.

[0005] Technological background

[0006] Foams are dispersions of gas bubbles in liquids or solid matrices. Surfactants or surface active agents such as detergents, wetting agents, emulsifiers or dispersants, which are commonly used in different industries, reduce the surface tension of a liquid and, given their amphiphilic nature, tend to accumulate at the air-liquid interfaces, delaying the coalescence of gas bubbles and therefore stabilizing the foam.

[0007] Antifoam compositions are systems that, when added to the foaming liquid, accelerate foam collapse relative to foam formation. These compositions are usually added in small concentrations. Antifoam agents have found application in a wide variety of manufacturing and processing processes, for example, paints and latexes, coating processes, textiles, fermentation processes, polymer manufacturing, cleaning compounds, pulp and paper, wastewater treatment, and cooling towers. The addition of silicone antifoam compositions has been found to be particularly effective in controlling foam. Silicone antifoam compositions are dispersions of hydrophobic particles such as silica in a silicone matrix. US3383327 describes a composition comprising silica dispersed and heated in a polydimethylsiloxane.

[0008] To achieve improved antifoam performance, polydimethylsiloxane can be partially replaced by a three-dimensional network or branched polymer.

[0009] To this end, EP0163541 describes a process for preparing a silicone antifoam by a polycondensation reaction at temperature using a reactive organopolysiloxane with hydroxyl or alkoxyl functions in the presence of a catalyst, silicone resin, a filler and non-reactive organopolysiloxanes. Furthermore, EP2794760 describes a process for preparing a silicone antifoam at temperature from a mixture of reactive organopolysiloxane with hydroxyl functions, two silicas, respectively hydrophobic and hydrophilic, and a silicone resin, in the presence of a catalyst. This is also a polycondensation reaction. Documents EP0434060, US8053480 and WO2021167728 describe silicone antifoams derived from polyaddition chemistry. Patent applications WO2020108750 and 751 combine polyaddition and polycondensation chemistry. High-energy radiation irradiation chemistry is also described in WO2021126195.

[0010] These silicone antifoams can, however, be viscous, which does not favor their use, and they are not easily dispersible in aqueous media. In addition, they sometimes exhibit viscoelastic behavior also known as the Weissenberg effect. This so-called effect is a manifestation of a non-zero difference in normal stresses typical of certain polymer solutions (viscoelastic fluids). The phenomenon is manifested by the rise of the liquid along a rotating rod immersed in such a viscoelastic fluid. This is why they are formulated as silicone emulsions in water thanks to the addition of emulsifiers. Different compositions are described to obtain silicone antifoam emulsions. For example, WO2016107987 describes a method for preparing silicone droplets in water with a silicone content limited to 10% by weight.Higher concentrations are described in WO1998000216 in which the examples consist of emulsions at 35% solids. Emulsifying silicone antifoams often requires the use of specific surfactants such as the sorbitan esters cited in WO1998000216 and WO2016107987 which prevent the silicone antifoam from breaking the interfacial layer of the emulsion.

[0011] For productivity and eco-design reasons, it is increasingly desirable to limit the water concentration and therefore increase the silicone concentration in silicone antifoam emulsions. However, it is well known in the field of emulsions that an increase in the droplet volume fraction greatly increases the viscosity. By increasing the concentration, the emulsions evolve from Newtonian behavior to non-Newtonian pseudo-plastic behavior and become very difficult to handle, pour, pump and disperse.

[0012] In this context, there is on the one hand a need for a silicone antifoam emulsion of high viscosity or viscoelastic nature, with a high concentration of silicone while maintaining low emulsion viscosities typically less than 6000 mPa.s, preferably less than 3500 mPa.s, exhibiting good storage stability and on the other hand for these emulsions to be dispersible in water to ensure the availability of the active part at the liquid-gas interfaces meaning that the antifoam performances must not be impacted by the species used for the emulsion.

[0013] In this context, the present invention aims to satisfy at least one of the following objectives.

[0014] An objective of the present invention is to provide a silicone antifoam emulsion simultaneously meeting these needs, namely high silicone concentration while maintaining a low, dispersible, storage-stable viscosity and exhibiting good antifoam properties. Another essential objective of the invention is to provide a process for preparing a silicone antifoam emulsion, said emulsion obtained simultaneously meeting these needs, namely high silicone concentration while maintaining a low, dispersible, storage-stable viscosity and exhibiting good antifoam properties.

[0015] Another essential objective of the invention is to provide a method for inhibiting the formation of foams using a concentrated, low-viscosity silicone antifoam emulsion that is dispersible, stable in storage and has good antifoam properties.

[0016] Summary of the invention

[0017] These objectives, among others, are achieved by the present invention which relates firstly to a silicone antifoam emulsion in water EA comprising:

[0018] - at least one first silicone antifoam emulsion in water EA1 with a volume average diameter EAI greater than or equal to 6 μm comprising: a) at least one silicone antifoam AS comprising from 0.1 to 10% by weight of at least one mineral filler C, b) optionally at least one organopolysiloxane B1, c) at least one emulsifier D1, d) at least one additive F1, e) water W1, and

[0019] - at least one second silicone emulsion in water E2 with a volume average diameter dE2 less than dEAi and characterized in that the silicone antifoam emulsion in water EA comprises a water content of less than 65% by weight, preferably less than 60% by weight and preferentially less than 55% by weight.

[0020] The invention also relates to a process for preparing a silicone antifoam emulsion in water EA, characterized in that it comprises the following essential steps: a) dispersion with stirring and at a temperature above 50°C and below 75°C of at least one silicone antifoam AS, optionally at least one organopolysiloxane B1, at least one emulsifier D1 and a portion of the water until the mixture is homogenized, b) cooling with stirring of the mixture obtained at the end of step a) to a temperature below or equal to 30°C and adding the second portion of water, then the additive F1 and stirring until the mixture is homogenized to obtain EA1, c) adding the silicone emulsion in water E2 to EA1 and stirring until the antifoam emulsion EA is completely homogenized.

[0021] The invention also relates to a method for inhibiting foam formation by adding an antifoam emulsion EA to the liquid surface.

[0022] Detailed description

[0023] EA silicone antifoam emulsion in water comprising:

[0024] - at least one first silicone antifoam emulsion in water EA1 with a volume average diameter dEAi greater than or equal to 6 μm comprising: a) at least one silicone antifoam AS comprising from 0.1 to 10% by weight of at least one mineral filler C, b) optionally at least one organopolysiloxane B1, c) at least one emulsifier D1, d) at least one additive F1, e) water W1, and

[0025] - at least one second silicone emulsion in water E2 with a volume average diameter dE2 less than dEAi and characterized in that the silicone antifoam emulsion in water EA comprises a water content of less than 65% by weight, preferably less than 60% by weight and preferentially less than 55% by weight.

[0026] The silicone antifoam emulsion in water EA is characterized in that it has a viscosity of less than 6000 mPa.s and preferably less than 3500 mPa.s.

[0027] All the viscosities referred to in the present disclosure correspond to a dynamic viscosity quantity at 25°C called “Newtonian”, that is to say the dynamic viscosity which is measured, in a manner known per se, with a Brookfield viscometer at a shear rate gradient sufficiently low so that the measured viscosity is independent of the rate gradient. According to another embodiment, the silicone antifoam emulsion in water EA is characterized in that the content of the silicone emulsion in water E2 is between 2 and 30% relative to the total weight of the silicone antifoam emulsion in water EA, preferably between 2.5 and 30% relative to the total weight of the silicone antifoam emulsion in water EA, more preferably between 4 and 24% and even more preferably between 6 and 20%.

[0028] According to another embodiment, the silicone antifoam emulsion in water EA is characterized in that the silicone emulsion in water E2 is an emulsion with a volume average diameter dE2 of between 0.01 and 6 μm.

[0029] The average particle size is measured by laser granulometry. The average particle size corresponds to the diameter D[4,3] which is the volume average diameter. The definition of the volume average diameter, D[4,3], is well known to those skilled in the art.

[0030] According to another embodiment, the silicone antifoam emulsion in water EA is characterized in that the silicone emulsion in water E2 is a silicone emulsion in water with a silicone concentration greater than 35% by weight of the total weight of E2.

[0031] According to another preferred embodiment, the silicone antifoam emulsion in water EA is characterized in that the silicone emulsion in water E2 comprises

[0032] - from 35 to 80 parts by weight of at least one organopolysiloxane B2,

[0033] - from 0.1 to 10 parts by weight of at least one emulsifier D2,

[0034] - from 0 to 5 parts by weight of at least one additive F2 and

[0035] - from 5 to 65 parts by weight of water W2 per 100 parts by weight of the sum of constituents B2, D2, F2 and W2.

[0036] The volume average diameter D[4,3] of the emulsion EA1 is preferably greater than 6 pm, preferably between 7 and 150 pm and preferably between 10 and 120 pm.

[0037] Adding to a silicone antifoam emulsion in water EA1 with a volume average diameter dEAi greater than 6 pm, a silicone emulsion in water E2 with a volume average diameter dE2 less than dEAi makes it possible to simultaneously obtain a concentrated silicone emulsion with low viscosity. This results in increased productivity, easier handling and transport, while maintaining good antifoam properties.

[0038] The silicone antifoam emulsion in water EA according to the invention simultaneously has a silicone content greater than 35%, a viscosity less than 6000 mPa.s, preferably less than 3500 mPa.s, good dispersibility in water, good storage stability and good antifoam properties.

[0039] E2 silicone emulsion is a water-based silicone emulsion based on organopolysiloxanes.

[0040] Organopolysiloxanes are described by the siloxyl units M, D, T, Q. The letter M represents the monofunctional unit of formula (R)sSiOi / 2, the silicon atom being linked to a single oxygen atom in the polymer comprising this unit. The letter D signifies a difunctional unit (R)2SiC>2 / 2 in which the silicon atom is linked to two oxygen atoms. The letter T represents a trifunctional unit of formula (R)SiOs / 2, in which the silicon atom is linked to three oxygen atoms. The letter Q represents a tetrafunctional unit of formula SiO4 / 2, in which the silicon atom is linked to four oxygen atoms. The symbol R has the same definition as the symbols R 2 , R 3 and R 4 defined below. The M, D, T motifs can be functionalized. We then speak of M, D, T motifs while specifying the specific radicals.

[0041] The silicone emulsion in water E2 comprises at least one organopolysiloxane B2, which can be chosen from the group consisting of:

[0042] - non-reactive organopolysiloxanes which, per molecule, have monovalent organic substituents, identical or different from each other, linked to the silicon atoms, and which are chosen from the group consisting of C1-C40 alkyl, C3-C8 cycloalkyl, C6-C10 aryl and C7-C50 alkylaryl radicals;

[0043] - reactive organopolysiloxanes comprising at least two silanol ^SiOH groups per molecule;

[0044] - and mixtures thereof. In the context of the invention, the term "non-reactive" means an organopolysiloxane which, under the conditions of emulsification, preparation of the silicone emulsion in water and use, does not react chemically with any of the constituents of the emulsion.

[0045] The non-reactive organopolysiloxane may be an oil or a gum, and preferably has a dynamic viscosity of between 50 and 600,000 mPa.s at 25°C or a consistency of between 200 and 2000 expressed in tenths of a millimeter at 25°C.

[0046] The dynamic viscosity of silicones is measured at 25°C according to ASTM D 445.

[0047] The term gum is used for organopolysiloxane compounds with viscosities typically greater than -600000 mPa.s, which corresponds to a molecular weight greater than 260000 g / mol.

[0048] The consistency or penetrability of a rubber is determined at 25°C using a PNR12 type penetrometer or equivalent model allowing a cylindrical head to be applied to the sample under standardized conditions.

[0049] The penetrability of a rubber is the depth expressed in tenths of millimeters to which a calibrated cylinder penetrates the sample for one minute.

[0050] For this purpose, a sample of rubber is placed in an aluminum cup with a diameter of 40 mm and a height of 60 mm. The cylindrical head made of bronze or brass measures 6.35 mm in diameter and 4.76 mm in height and is carried by a metal rod 51 mm long and 3 mm in diameter which fits the penetrometer. This rod is weighted with a surcharge of 100 g. The total weight of the assembly is 151.8 g, of which 4.3 for the cylindrical part and its support rod. The cup containing the sample of rubber is placed in the thermostatic bath at 25 ± 0.5 °C for at least 30 minutes. The measurement is carried out following the manufacturer's instructions. The values ​​of the depth (V) in tenths of a millimeter and the time (t) in seconds to reach this depth are indicated on the device. The penetrability is equal to 60 V / t expressed in tenths of a millimeter per minute.The non-reactive organopolysiloxane gums that can be used in accordance with the invention are used alone or as a mixture in an inorganic solvent. This solvent can be chosen from volatile silicones, octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), polydimethylsiloxane oils (PDMS), polyphenylmethylsiloxane oils (PPMS) or mixtures thereof, in order to avoid the use of organic solvents that are harmful to the environment and the health of workers in tire manufacturing workshops.

[0051] Advantageously, the non-reactive organopolysiloxane is a non-reactive linear organopolysiloxane oil which is a linear homopolymer or copolymer. Preferably, the non-reactive linear organopolysiloxane oil has a dynamic viscosity of the order of 0.65 to 100,000 mPa.s at 25°C. Examples of linear organopolysiloxanes include:

[0052] - consisting along each chain: i) units of formula R 5 R 6 SiC>2 / 2, possibly associated with motifs of formula (R 5 )2SiC>2 / 2; ii) motifs of formula (R 6 )2SiC>2 / 2, possibly associated with motifs of formula (R 5 )2SiC>2 / 2, iii) motifs of formula R 5 R 6 SiC>2 / 2 and motifs of formula (R 6 )2SiC>2 / 2, possibly associated with motifs of formula (R 5 )2SiC>2 / 2,

[0053] - and blocked at each end of the chain by a motif of formula (R 7 )sSiOi / 2 whose radicals R 7 , identical or different, are chosen from radicals R 5 and R 6 ,

[0054] - where the radicals R 5 and R 6 , monovalent organic substituents of the various siloxyl units mentioned above, have the following definitions: a) the radicals R 5, identical or different from each other, are chosen from;

[0055] 1. linear C 1 -C 6 or branched C 3 -C 6 alkyl radicals such as, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, n-pentyl, n-hexyl, and

[0056] 2. Cs-Cs cycloalkyl radicals such as for example cyclopentyl, cyclohexyl, b) radicals R 6 , identical or different from each other, are chosen from

[0057] 1. Ce-Cio aryl radicals such as phenyl, naphthyl,

[0058] 2. C7-C15 alkylaryl radicals such as, for example, tolyl, xylyl, and

[0059] 3. C7-C15 arylalkyl radicals such as, for example, benzyl. The reactive organopolysiloxane may be an oil or a gum, and preferably has a dynamic viscosity of between 50 and 600,000 mPa.s at 25°C or a consistency of between 200 and 2,000 expressed in tenths of a millimeter at 25°C.

[0060] Preferably, the reactive organopolysiloxane of the silicone emulsion in water E2 comprises the following siloxyl units:

[0061] M° H = [(OH)(R 2 )2SiOi / 2] and D= [R 3 R 4 SiO2 / 2] in which:

[0062] R 2 , R 3 and R 4 are radicals, identical or different, chosen from the group consisting of:

[0063] - linear or branched C1-C6 alkyl radicals such as, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, n-pentyl, n-hexyl;

[0064] - Cs-Cs cycloalkyl radicals such as, for example, cyclopentyl, cyclohexyl;

[0065] - Ce-Cio aryl radicals such as for example phenyl, naphthyl; and

[0066] - C7-C15 alkylaryl radicals such as for example tolyl, xylyl.

[0067] The silicone-in-water emulsion E2 also includes an emulsifier D2. The nature of the emulsifier D2 will be easily determined by those skilled in the art, the objective being to prepare a stable emulsion. The anionic, cationic, non-ionic and zwitterionic surfactants can be used alone or in mixtures.

[0068] It should be noted that the silicone emulsion in water E2 can also include protective colloids such as polyvinyl alcohol, as described in patent EP0946240.

[0069] As anionic surfactant, the following surfactants can be mentioned:

[0070] - alkyl ester sulfonates of formula R a -CH(SC>3M)-COOR b , where R a represents a Cs-C2o, preferably C10-C16, alkyl radical, R ba C1-C6 alkyl radical, preferably C1-C3 and M an alkali metal cation (sodium, potassium, lithium), substituted or unsubstituted ammonium (methyl-, dimethyl-, trimethyl-, tetramethylammonium, dimethylpiperidinium) or alkanolamine derivative (monoethanolamine, diethanolamine, triethanolamine), - alkyl sulfates of formula R c OSC>3M, where R c represents a C10-C24, preferably C12-C20, alkyl or hydroxyalkyl radical, M representing a hydrogen atom or a cation of the same definition as above, as well as their ethoxylated (EO) and / or propoxylated (OP) derivatives, preferably having from 1 to 20 EO units,

[0071] - alkylamide sulfates of formula R d CONHR e OS03M where R d represents a C2-C22, preferably C6-C20, alkyl radical, R ea C2-C3 alkyl radical, M representing a hydrogen atom or a cation of the same definition as above, as well as their ethoxylated (EO) and / or propoxylated (OP) derivatives, preferably having 1 to 20 EO units,

[0072] - salts of saturated or unsaturated C8-C24, preferably C14-C20, fatty acids, C9-C20 alkylbenzenesulfonates, as well as their ethoxylated (EO) and / or propoxylated (PO) derivatives, preferably having 1 to 20 EO units, - C9-C20 alkylbenzenesulfonates, primary or secondary C8-C22 alkylsulfonates, alkylglycerol sulfonates, sulfonated polycarboxylic acids described in GB-A-1 082 179, paraffin sulfonates, N-acyl N-alkyltaurates, mono- and dialkylphosphates, alkylisethionates, alkylsuccinamates, alkylsulfosuccinates, monoesters or diesters of sulfosuccinates, N-acyl sarcosinates, sulfates alkylglycosides, polyethoxycarboxylates, the cation being an alkali metal (sodium, potassium, lithium), a substituted or unsubstituted ammonium residue (methyl-, dimethyl-, trimethyl-, tetramethylammonium, dimethylpiperidinium) or derived from an alkanolamine (monoethanolamine, diethanolamine, triethanolamine).

[0073] Examples of non-ionic surfactants include poly(alkylene oxide) alkyl or aryl ethers, polyoxyethylene sorbitan hexastearate, polyoxyethylene sorbitan oleate and cetylstearyl poly(ethylene oxide) ethers. Examples of poly(alkylene oxide) aryl ethers include polyoxyethylene alkylphenols. Examples of poly(alkylene oxide) alkyl ethers include polyethylene glycol isodecyl ether and polyethylene glycol trimethylnonyl ether containing 3 to 15 ethylene oxide units per molecule. Examples of surfactants include: ionic, non-ionic or amphoteric fluorinated surfactants and mixtures thereof, for example:

[0074] - perfluoroalkyls,

[0075] - perfluorobetaines,

[0076] - ethoxylated polyfluoroalcohols,

[0077] - ammonium polyfluoroalkyls,

[0078] - surfactants whose hydrophilic part contains one or more saccharide unit(s) carrying five to six carbon atoms and whose hydrophobic part contains a unit of formula R f (CH2)n-, in which n = 2 to 20 and Rf represents a perfluoroalkyl unit of formula CmF2m+i, in which m = 1 to 10; and

[0079] - polyelectrolytes having fatty perfluoroalkyl side groups.

[0080] By fluorinated surfactant is meant, as is perfectly known per se, a compound formed from an aliphatic perfluorocarbon part, comprising at least three carbon atoms, and a hydrophilic, ionic, non-ionic or amphoteric part. The perfluorocarbon part of at least three carbon atoms can represent either all or only a fraction of the fluorocarbon part of the molecule. Concerning this type of compound, a large number of references can be found in the literature. Those skilled in the art may refer in particular to the following references:

[0081] - FR-A-2 149 519, WO-A-94 21 233, US-A-3, 194,767, the work "Fluorinated Surfactants", Erik Kissa, Publisher Marcel Dekker Inc. (1994) Chapter 4, in particular Tables 4.1 and 4.4.

[0082] In particular, we can cite the products sold by the Du Pont company under the name ZONYL®, for example FSO, FSN-100, FS-300, FSD, as well as the fluorinated surfactants under the name FORAFAC® distributed by the DU PONT company and the products sold under the name FLUORAD® by the 3M company.

[0083] Among these surfactants, mention will be made, in particular, of anionic, cationic, non-ionic and amphoteric perfluoroalkyl compounds, and among them, more particularly, the surfactants of the ZONYL® class marketed by DU Pont, marketed by Du Pont respectively under the names ZONYL® FSA, ZONYL® FSO, ZONYL® FSC and ZONYL® FSK. It may also be specified with regard to them:

[0084] - ZONYL® FSO 100: CAS 65545-80-4, (non-ionic) 99 to 100%, the remainder being 1,4-dioxane,

[0085] - ZONYL® FSN: CAS 65545-80-4, 99 to 100%, the remainder being sodium acetate and 1,4-dioxane,

[0086] - ZONYL® FS-300: CAS 65545-80-4, 40%, the remainder being 1,4-dioxane (<0.1%) and water,

[0087] - ZONYL®FSD: CAS 70983-60-7 30%, (cationic), the remainder being hexylene glycol (10%), sodium chloride (3%) and water (57%).

[0088] We can also cite:

[0089] - perfluoroalkyl betaines (amphoterics) such as that marketed by DU PONT under the name FORAFAC® 1157, ethoxylated polyfluoroalcohols (non-ionic), such as that marketed by DU PONT under the name FORAFAC 1110 D, polyfluoroalkyl ammonium salts (cationic), such as that marketed by DU PONT under the name FORAFAC 1179;

[0090] - surfactants whose hydrophilic part contains one or more saccharide unit(s) containing 5 to 6 carbon atoms (units derived from sugars such as fructose, glucose, mannose, galactose, talose, gulose, allose, altose, idose, arabinose, xylose, lyxose and / or ribose) and whose hydrophobic part contains a unit of formula R F (CH2)n, where n can range from 2 to 20, preferably from 2 to 10 and R F represents a perfluoroalkyl unit of formula CmF2m+i with m ranging from 1 to 10, preferably from 4 to 8, chosen from those having the characteristics defined above; mention may be made of monoesters of perfluoroalkylated fatty acids and sugars such as sucrose, the monoester function being able to be represented by the formula R F (CH2)nC(O), where n can range from 2 to 10 and R Frepresents a perfluoroalkyl unit of formula CmF2m+i with m ranging from 4 to 8, described in Journal of the American Oil Chemists' Society (JAOCS), Vol. 69, No. 1 (January 1992) and chosen from those having the characteristics defined above; and

[0091] - polyelectrolytes having fatty perfluoroalkyl side groups such as polyacrylates having R groups F (CH2)n where n can range from 2 to 20, preferably from 2 to 10 and R F represents a perfluoroalkyl unit of formula CmF2m+i with m ranging from 1 to 10, preferably from 4 to 8, chosen from those having the characteristics defined above; mention may be made of polyacrylates having — CH2C7F15 groups described in J. Chim. Phys. (1996) 93, 887-898 and chosen from those having the characteristics defined above.

[0092] The amount of emulsifier D2 depends on the type of each of the constituents present as well as the nature of the emulsifier used. As a general rule, the emulsion comprises from 0.1 to 10% by weight of emulsifier relative to the total weight of the emulsion.

[0093] Furthermore, in a conventional and non-limiting manner, F2 additives such as film-forming polymers, biocides, rheology modifiers, coalescing agents, dispersing agents, acidifying agents, neutralizing agents, bases and / or thickening agents alone or in a mixture can also be used in the emulsions.

[0094] The concentrations of such adjuvants are known to those skilled in the art.

[0095] According to another embodiment, the silicone antifoam emulsion in water EA is characterized in that the silicone antifoam AS is obtained by polycondensation chemistry.

[0096] Said polycondensation chemistry is well known to those skilled in the art. Without being limiting, examples that may be cited are documents EP0163541 and EP2794760.

[0097] According to another embodiment, the silicone antifoam emulsion in water EA is characterized in that the silicone antifoam AS is obtained by polyaddition chemistry.

[0098] Said polyaddition or hydrosilylation chemistry is well known to those skilled in the art. Without being limiting, examples that may be cited are documents EP0434060, US8053480, WO2018224131 and WO2021167728. According to another embodiment, the silicone antifoam emulsion in water EA is characterized in that the silicone antifoam AS is obtained by radical chemistry.

[0099] Said radical chemistry is well known to those skilled in the art. Without being limiting, we can cite for example document WO2021126195.

[0100] According to another embodiment, the silicone antifoam emulsion in water EA is characterized in that the silicone antifoam AS is obtained by mixing different silicone antifoams AS.

[0101] The mineral filler C of the silicone antifoam AS is a compound selected from the group comprising silicas, preferably combustion silicas and / or precipitation silicas and / or colloidal silicas, diatomaceous earths, ground quartz, calcium carbonate, hydrated alumina, magnesium hydroxide, carbon black, titanium dioxide, aluminum oxide, vermiculite, zinc oxide, mica, talc, iron oxide, barium sulfate, slaked lime, and mixtures thereof.

[0102] The mineral filler C of the silicone antifoam AS is preferably silica. It may be precipitated silica or combustion silica, treated or untreated. The precipitated silica is preferably prehydrophobicized by conventional treatment with one or more organosilicon compounds. It may be incorporated untreated, then treated (hydrophobicized) in situ with one or more organosilicon compounds. These compounds include methylpolysiloxanes such as hexamethyldisiloxane, octamethylcyclotetrasiloxane, methylpolysilazanes such as hexamethyldisilazane, hexamethylcyclotrisilazane, chlorosilanes such as dimethyldichlorosilane, trimethylchlorosilane, methylvinyldichlorosilane, dimethylvinylchlorosilane, alkoxysilanes such as dimethyldimethoxysilane. During this treatment, silicas can increase their initial weight by up to 20%. Combustion silica can be used untreated.If necessary, however, it can be treated like precipitated silica.

[0103] Mineral fillers C generally have a specific surface area, measured according to BET methods, of at least 10 m 2 / g, particularly between 20 and 300 m 2 / g. A mixture of C fillers can be used.

[0104] The content of mineral filler C is generally between 0.1 and 10% by weight of the silicone antifoam AS, preferably between 0.5 and 10% by weight of the silicone antifoam AS.

[0105] The silicone antifoam AS or the silicone antifoam emulsion in water EA1 may optionally contain polyether silicones to improve the antifoam properties. These are well known to those skilled in the art. By way of non-limiting illustration, reference may be made to documents WO2020228212, EP3423165, EP2563491 and EP2563491.

[0106] According to another embodiment, the silicone antifoam emulsion in water EA is characterized in that it comprises a silicone antifoam emulsion in water EA1 with a water content of less than 65% by weight and a silicone emulsion in water E2 with a water content of less than 65% by weight.

[0107] According to another embodiment, the silicone antifoam emulsion in water EA is characterized in that the particle size distribution of the dispersed silicone phases is of the bimodal type with a ratio of percentage of large particles / percentage of fine particles of between 98 / 2 and 60 / 40, the percentage of large particles being calculated as follows: (weight of silicone antifoam AS + weight of organopolysiloxane B1 + weight of emulsifiers D1) of the antifoam emulsion EA1 / Sum of ((weight of silicone antifoam AS + weight of organopolysiloxane B1 + weight of emulsifiers D1) of the antifoam emulsion EA1 and the weight of dry matter of the emulsion E2) and the percentage of fine particles being the complement to 100%.

[0108] Preferably, the ratio of large particle percentage to fine particle percentage of the EA antifoam emulsion is between 98 / 2 and 70 / 30.

[0109] According to another embodiment, the silicone antifoam emulsion in water EA is characterized in that it comprises per 100 parts by weight of antifoam emulsion EA:

[0110] - from 70 to 98 parts by weight of a silicone antifoam emulsion in water EA1 with a volume average diameter dEAi greater than or equal to 6 μm comprising: a) from 15 to 55 parts by weight of at least one silicone antifoam AS comprising from 0.1 to 10 parts by weight of at least one mineral filler C, b) from 0 to 25 parts by weight of at least one organopolysiloxane B1, c) from 0.1 to 12 parts by weight of at least one emulsifier D1, d) from 0.01 to 5 parts by weight of at least one additive F1, e) from 3 to 65 parts by weight of water W1 and

[0111] - from 2 to 30 parts by weight of at least one second silicone emulsion in water E2 with a volume average diameter dE2 less than dEAi.

[0112] Organopolysiloxane B1 may be the same as or different from B2 and may be reactive or non-reactive as described for B2.

[0113] Emulsifier D1 may be the same or different from D2. It may be a protective colloid such as polyvinyl alcohol or a non-ionic, anionic, or cationic surfactant alone or in a mixture.

[0114] Additive F1 may be the same or different from F2.

[0115] Another subject of the present invention relates to a process for preparing a silicone antifoam emulsion in water EA, characterized in that it comprises the following essential steps: a) dispersion with stirring and at a temperature above 50°C and below 75°C of at least one silicone antifoam AS, optionally at least one organopolysiloxane B1, at least one emulsifier D1 and a portion of the water until the mixture is homogenized, b) cooling with stirring of the mixture obtained at the end of step a) to a temperature below or equal to 30°C and adding the second portion of water, then the additive F1 and stirring until the mixture is homogenized to obtain EA1, c) adding the silicone emulsion in water E2 to EA1 and stirring until the silicone antifoam emulsion in water EA is completely homogenized.

[0116] More particularly, the invention relates to a method for inhibiting the formation of foams by adding a silicone antifoam emulsion in water EA, to the surface of the liquid. Other advantages and characteristics of the present invention will appear on reading the following examples given for illustrative purposes only and are not limiting.

[0117] Examples

[0118] In the following examples, different silicone antifoams AS, polydimethylsiloxane silicone oils B1, silicone emulsions in water E2 and emulsifiers D1 were used to prepare silicone antifoam emulsions in water EA according to the invention. Unless otherwise stated, throughout this document, the % are expressed as % by weight.

[0119] Raw materials used

[0120] Different commercial AS antifoams with a silica C content between 0.5 and 10% were used:

[0121] - Silcolapse ™ 825, sold by the company Elkem Silicones, is a silicone AS antifoam derived from polycondensation chemistry as described in EP0163541;

[0122] - Silcolapse ® 120, sold by the company Elkem Silicones, is a silicone antifoam AS as described in US3383327;

[0123] - Silcolapse ® 490, sold by the company Elkem Silicones, is a silicone AS antifoam resulting from polycondensation chemistry as described in EP0163541.

[0124] Bluesil™ FLD 47V350, sold by Elkem Silicones, is a non-reactive B1 polydimethylsiloxane silicone oil with a viscosity of -350 mPa.s.

[0125] Bluesil™ FLD 48V135000, sold by Elkem Silicones, is a reactive polydimethylsiloxane (a,œ-di hydroxy) B1 silicone oil with a viscosity of -135000 mPa.s.

[0126] Different commercial E2 emulsions were used:

[0127] - Bluesil ™ Emul 872, sold by the company Elkem Silicones, is an E2 emulsion of non-reactive B2 polydimethylsiloxane silicone oil 47V350 at -61% dry matter and with a volume average diameter D[4.3] of 0.16pm;

[0128] - Bluesil Emul 284, from Elkem Silicones, is an E2 emulsion of reactive polydimethylsiloxane (a,œ-dihydroxy) silicone oil B2 48V135000 at -51% dry matter and with a volume average diameter D[4,3] of 0.26pm.

[0129] Radiasurf 7145, sold by Oleon, is a D1 emulsifier: Sorbitan monostearate. Myrj S40, sold by Croda, is a D1 emulsifier: PEG-40 stearate. Rhodasurf ROX, sold by Solvay, is a D2 emulsifier: ethoxylated branched alcohol.

[0130] Proxel GXL, sold by Lonza, is an F1 additive: 20% solution of 1,2-benzisothiazolin-3-one.

[0131] Characterization of emulsions - measurement methods:

[0132] The dry extract is expressed as % residue and is measured using a halogen moisture analyzer (1g - 105°C - 60 min).

[0133] The viscosity of the emulsion is measured initially and after 1 month at 40°C using a Brookfield viscometer (A4V20).

[0134] The PSD particle size distribution is measured with a Mastersizer 3000 Laser Granulometer from Malvern. D[4,3] corresponds to the volume average diameter and is expressed in pm.

[0135] The ease of use of emulsions is estimated by filtration through a 250 µm nylon sieve.

[0136] To estimate the dispersibility of the emulsion, a drop of emulsion is placed in a cylindrical tube 4.5 cm high and 1.4 cm in diameter, filled with 3 ml of deionized water, from a pipette. The number of complete inversions required for total dispersibility is quantified. The emulsion is considered dispersible if the number of complete inversions is less than 10, preferably less than 5.

[0137] Regarding storage stability, it is visually checked every two months. The number of months after which a phase shift is observed is noted.

[0138] The antifoam properties are verified using a recirculation test. 800 ml of detergent solution (aqueous solution at 3 g / l of sodium dodecyl benzene sulfonate and C12-C18 fatty alcohol ethoxylated on average 7 times) are pumped in recirculation into a 2 liter test tube at a flow rate of 200 l / h at 60°C. As soon as the foam level reaches the H1 graduation in ml, 50 mg of antifoam emulsion are injected, and the foam level is monitored over time. Initially, the foam level drops, and the reading of its low point (H2 in ml) allows the calculation of the "shock effect" (1 -(H2 / H 1)), expressed as a percentage. Compositions and characteristics of EA emulsions obtained from a single silicone antifoam AS.

[0139] [Table 1]

[0140] Example 1 according to the invention: In a glass container equipped with a stirring anchor, load 154g of Silcolapse 825 AS, 110g of Bluesil 47V350 B1, 49.5g of Radiasurf 7145 D1, 16.6g of Myrj S40 D1 and 65.1g of deionized water W1 (first part). Stir at 60 rpm for 45 minutes while heating until a temperature of 65°C is reached in order to melt the emulsifiers and homogenize the mixture.

[0141] Stirring is then increased to 150 rpm for 20 minutes before cooling the mixture to 30°C, at which temperature 329 g of deionized water W1 (second part) are added over one hour at a rate of 10 rpm while continuing to cool to room temperature. The stirring speed is increased to 50 rpm for 25 minutes. Then add over 15 minutes, 176 g of Bluesil Emul 872 E2 emulsion. Finally add 1.4 g of Proxel GXL F1 and continue stirring for 15 minutes.

[0142] The concentrated silicone antifoam emulsion in water obtained is a white emulsion with a bimodal particle size distribution, a volume average diameter [D(4.3)] of 54 pm, a dry extract of 48% and a viscosity of 270 mPa.s, i.e. ~ 37 times lower than comparative example 1 with comparable dry extract. Unlike comparative example 1, the emulsion is also filtered without problem through a 250 pm sieve and is dispersible. Its viscosity after one month at 40°C is well below 3500 mPa.s. if 1 The procedure is as in Example 1 except for the addition of Bluesil Emul 872 E2 emulsion and this with the quantities of each ingredient mentioned in Table 1. In the absence of Bluesil Emul 872 E2 emulsion, the emulsion obtained has a monomodal particle size distribution, the volume average diameter [D(4.3)] is ~90 pm, the viscosity is greater than 10000 mPa.s for a dry extract comparable to Example 1 according to the invention. Unlike Example 1 according to the invention, the emulsion cannot be filtered through a 250 pm sieve, its dispersibility is poor and a phase shift is observed after 4 months.

[0143] Compositions and characteristics of EA emulsions obtained from a mixture of 2 silicone AS antifoams.

[0144] [Table 2]

[0145]

[0146] Examples 2 to 5 according to the invention: The procedure is as for example 1 with the quantities of each ingredient mentioned in table 2. A mixture of 2 silicone antifoams AS is used instead of just one. White emulsions are obtained having a bimodal particle size distribution, a volume average diameter [D(4.3)] between 34 and 13 pm, a viscosity of less than 6000 mPa.s for a dry extract close to 50%, namely a viscosity 2 to 10 times lower than comparative example 2 with a comparable dry extract. All the emulsions are filterable through a 250 pm sieve, have good dispersibility, namely less than or equal to 5 inversions, a viscosity after one month at 40°C of less than 6000 mPa.s. No phase separation is observed after 12 months of storage, while still presenting good anti-foam properties: the measured shock effect is greater than 89%.Comparative example 2: The procedure is as in examples 2 to 5 except for the addition of emulsion E2 and this with the quantities of each ingredient mentioned in table 2. The emulsion obtained is a very viscous white paste with a monomodal particle size distribution. The volume average diameter is ~70|jm, the viscosity is greater than 10000 mPa.s for a dry extract comparable to examples 2 to 5 according to the invention. Unlike examples 2 to 5 according to the invention, the emulsion cannot be filtered on a 250 μm sieve, its dispersibility is poor (> 20 inversions) and a phase shift is observed after 6 months.

[0147] Compositions and characteristics of EA emulsions obtained from emulsions

[0148] E2 of different average diameter in volume.

[0149] [Table 3]

[0150] Preparation of E2 emulsions:

[0151] Bluesil Emul 284 type emulsion: E2 D[4.3]=3.5|jm

[0152] In a glass container equipped with a stirring anchor, charge 195g of Bluesil FLD 48V135 000 B2 oil, 16.1g of Rhodasurf ROX D2 and 6.5g of deionized water W2 (first part). Stir at 30 rpm for 20 minutes, then add 134g of deionized water W2 (second part) over 15 minutes. When all the water is incorporated, continue stirring for 15 minutes at 100 rpm, and add 0.5g of Proxel GXL F2. The resulting silicone oil-in-water emulsion is a white emulsion with a volume average diameter [D(4.3)] of 3.5 μm and a solids content of 58.5%.

[0153] Bluesil Emul 284 type emulsion: E2 D[4.3]=5.5|jm

[0154] In a glass container equipped with a stirring anchor, charge 177g of Bluesil FLD 48V135 000 B2 oil, 9.6g of Rhodasurf ROX D2 and 9.0g of deionized water W2 (first part). Stir at 40 rpm for 10 minutes, then add 157g of deionized water W2 (second part) over 20 minutes. When all the water is incorporated, continue stirring for 15 minutes at 100 rpm, and add 0.5g of Proxel GXL F2. The resulting silicone oil-in-water emulsion is a white emulsion with a volume average diameter [D(4, 3)] of 5.5 μm and a solids content of 51.6%.

[0155] 6 to 9 according to the invention The procedure is as for example 1 with the quantities of each ingredient mentioned in table 3. E2 emulsions of different volume average diameters are used. White emulsions are obtained having a bimodal particle size distribution, a volume average diameter [D(4,3)] between 12.3 and 4.5 pm, a viscosity lower than 6000 mPa.s for a dry extract close to 66%, namely a viscosity 2 to 7 times lower than comparative example 3 with comparable dry extract. All the emulsions are filterable on a 250 pm sieve, have good dispersibility, namely less than or equal to 5 inversions, a viscosity after one month at 40°C lower than 6000 mPa.s. if 3 The procedure is as in Examples 6 to 9 except for the addition of emulsion E2 and this with the quantities of each ingredient mentioned in Table 3. The emulsion obtained is a viscous white paste with a monomodal particle size distribution. The volume average diameter is ~70 pm and the viscosity is 9950 mPa.s for a dry extract comparable to Examples 6 to 9 according to the invention. Unlike Examples 6 to 9 according to the invention, the emulsion cannot be filtered through a 250 pm sieve and its dispersibility is poor (9 inversions).

Claims

Demands 1. Silicone antifoam emulsion in water EA comprising: - at least one first silicone antifoam emulsion in water EA1 with a volume mean diameter dEAi greater than or equal to 6 pm comprising: a) at least one silicone antifoam AS comprising from 0.1 to 10% by weight of at least one mineral filler C, b) optionally at least one organopolysiloxane B1, c) at least one emulsifier D1, d) at least one additive F1, e) water W1, and - at least one second silicone emulsion in water E2 of average volume diameter dE2 less than dEAi and characterized in that the silicone antifoam emulsion in water EA comprises a water content of less than 65% by weight.

2. Silicone antifoam emulsion in water EA according to claim 1, characterized in that it has a viscosity of less than 6000 mPa.s.

3. Silicone antifoam emulsion in water EA according to claim 1, characterized in that the content of the silicone emulsion in water E2 is between 2 and 30% relative to the total weight of the silicone antifoam emulsion in water EA.

4. Silicone antifoam emulsion in water EA according to claim 1, characterized in that the silicone emulsion in water E2 is an emulsion with a volume average diameter dE2 between 0.01 and 6 pm.

5. Silicone antifoam emulsion in water EA according to claim 1, characterized in that the silicone emulsion in water E2 is a silicone emulsion in water with a silicone concentration greater than or equal to 35% by weight of the total weight of E2.

6. Silicone antifoam emulsion in water EA according to claim 1, characterized in that the silicone emulsion in water E2 comprises - 35 to 80 parts by weight of at least one organopolysiloxane B2, - from 0.1 to 10 parts by weight of at least one D2 emulsifier, - 0 to 5 parts by weight of at least one F2 additive and - from 5 to 65 parts by weight of water W2 for 100 parts by weight of the sum of constituents B2, D2, F2 and W2.

7. Silicone antifoam emulsion in water EA according to claim 1, characterized in that the silicone antifoam AS is obtained by a polycondensation chemistry.

8. Silicone antifoam emulsion in water EA according to claim 1, characterized in that the silicone antifoam AS is obtained by a polyaddition chemistry.

9. Silicone antifoam emulsion in water EA according to claim 1, characterized in that the silicone antifoam AS is obtained by radical chemistry.

10. Antifoam emulsion EA silicone in water according to claim 1, characterized in that the silicone antifoam AS is obtained by mixing different silicone antifoams AS.

11. Silicone antifoam emulsion in water EA according to claim 1, characterized in that it comprises a silicone antifoam emulsion in water EA1 of water content less than 65% and a silicone emulsion in water E2 of water content less than 65%.

12. Silicone antifoam emulsion in water EA according to claim 1 characterized in that the particle size distribution of the dispersed oily phases is of the bimodal type with a ratio of percentage large particles / percentage fine particles between 98 / 2 and 60 / 40, the percentage of large particles being calculated as follows: (weight silicone antifoam AS + weight organopolysiloxane B1 + weight emulsifiers D1) of the antifoam emulsion EA1 / Sum of the ((weight silicone antifoam AS + weight organopolysiloxane B1 + weight emulsifiers D1) of the antifoam emulsion EA1 and the weight of dry matter of the emulsion E2) and the percentage of fine particles being the complement to 100%.

13. Silicone antifoam emulsion in water EA according to any one of claims 1 to 12, characterized in that it comprises, for 100 parts by weight of antifoam emulsion EA: - 70 to 98 parts by weight of a silicone antifoam emulsion in water EA1 with a mean volume diameter dEAi greater than or equal to 6 pm comprising: a) 15 to 55 parts by weight of at least one silicone antifoam AS comprising 0.1 to 10 parts by weight of at least one mineral filler C, b) 0 to 25 parts by weight of at least one organopolysiloxane B1, c) 0.1 to 12 parts by weight of at least one emulsifier D1, d) 0.01 to 5 parts by weight of at least one additive F1, e) 3 to 65 parts by weight of water W1 and - 2 to 30 parts by weight of at least a second silicone emulsion in water E2 of average diameter by volume dE2 less than dEAi.

14. A process for preparing a silicone antifoam emulsion in water EA according to claim 1, characterized in that it comprises the following essential steps: a) dispersion under stirring and at a temperature above 50°C and below 75°C of at least one silicone antifoam AS, optionally of at least one organopolysiloxane B1, of at least one emulsifier D1 and of a part of the water, until homogenization of the mixture, b) cooling under stirring of the mixture obtained at the end of step a) to a temperature less than or equal to 30°C and addition of the second part of the water, then of the additive F1 and stirring until homogenization of the mixture to obtain EA1, c) addition in EA1 of the silicone emulsion in water E2 and stirring until complete homogenization of the silicone antifoam emulsion in water EA.

15. A method for inhibiting foam formation by adding a silicone antifoam emulsion in water EA to the liquid surface, characterized in that the silicone antifoam emulsion in water EA is that according to claims 1 to 13 or obtained according to claim 14.

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