Composition of hydro-expandable liquid and its uses

Abstract

The present invention relates to the technical field of conditioning agents used in particular to block water ingress or to locally retain certain active molecules, such as fertilizers, during their dissolution in the presence of water (irrigation, rain, etc.) and thus prevent their leaching into the soil or to dry sludge. The hydro-expandable liquid composition of the invention is in the form of a dispersion comprising at least 10% and up to 40% by weight of a superabsorbent polymer in powder form, in an inverse emulsion previously distilled from an anionic or nonionic, linear, branched, or cross-linked organic polymer.

Description

Title of the invention: Hydro-expandable liquid composition and its uses

[0001] The present invention relates to the technical field of conditioning agents used in particular to block water ingress or to locally retain certain active molecules, such as fertilizers, during their dissolution in the presence of water (irrigation, rain, etc.) and thus prevent their leaching into the soil or to dry sludge. The hydro-expandable liquid composition of the invention is in the form of a dispersion comprising at least 10% and up to 40% by weight of a superabsorbent polymer in powder form, in an inverse emulsion previously distilled from an anionic or nonionic, linear, branched, or cross-linked organic polymer. Technical field of the invention

[0002] The invention relates to a new water-expandable liquid composition capable of swelling in the presence of water or aqueous solutions. Due to its ease of use, it meets various needs, such as: - For sealing cables (network, electrical, control): longitudinal sealing is designed with a barrier that prevents moisture from spreading along the cable, - or to prevent the leaching into the soil of products that are either high value added, such as fertilizers, or polluting. - or to dry out the sludge.

[0003] Packaging based on a material that swells upon contact with water, called a hydro-expansive material, designed to block water ingress and / or, conversely, to prevent any leaching, is then generally necessary. Among the existing packaging options, the use of a superabsorbent polymer can be mentioned. Superabsorbent polymers (SAPs) are polymers that can absorb and retain very large quantities of an aqueous liquid. They can thus absorb and retain up to several hundred times their mass in water.

[0004] The invention relates to a new water-expandable liquid composition in the form of a very stable, non-settling liquid dispersion of superabsorbent polymer(s) powder dispersed in an organic and / or mineral oil, having a high superabsorbent polymer content and characterized by the presence of a second organic polymer. Due to its ease of use, the new liquid composition of the invention allows, at very low dosages, the sealing of cables, and also prevents leaching of the fertilizers in the soils or also to absorb the liquid part of the sludge for its drying. Technical background

[0005] Among compositions comprising a superabsorbent polymer and a second organic polymer, patent FR3114980 of the applicant is known, which proposes to greatly improve the efficiency of the chemical conditioning of salt sludge through the combined use of a superabsorbent polymer (SAP) and a flocculant. However, this composition is in powder form.

[0006] Unlike powder formulations, compositions in liquid form, such as a dispersion, also called a suspension (an oil phase) or an emulsion (an oil phase and a water phase), greatly simplify the infrastructure required for their implementation and reduce the capital costs necessary for their use / preparation. However, it is well known to those skilled in the art that these liquid compositions have two major drawbacks: - a generally low percentage of active agents - and a relatively high risk of instability, namely phase separation (the oil and polymer molecules separate when exposed to cold, heat, during transport, or during storage...), which greatly reduces their effectiveness and shelf life. These two major drawbacks are the main obstacles to their commercial development. Presentation of the invention

[0007] Superabsorbent polymers belong to a group of polymers capable of absorbing large quantities of water or aqueous liquid (100, 200, 300 times or even more their weight in water). They are in the form of a white powder. When these polymers absorb water, they swell (they are said to be hydro-expandable) and form a gel, which gives them properties that allow for a wide range of uses. They are used, among other things: - for several decades in agriculture, particularly in regions with low rainfall and sandy soil. Their function is to retain water and water-soluble fertilizers and redistribute them as needed by the plant; - for the conditioning of sludge by drying it to facilitate handling, optimize and secure its transport, and allow, when possible, its recycling. - as a material blocking water ingress. They are used in water-repellent tapes / ointments / films and prevent water from entering cable assemblies (network, electrical, control), thus guaranteeing their longevity and reliability...

[0008] The applicant carried out numerous tests and unexpectedly obtained a new extremely stable and efficient dispersion having a high superabsorbent polymer content by mixing - at least 10% and up to 40% by weight relative to the total weight of the composition obtained of a powdered superabsorbent polymer - with a previously distilled inverse emulsion of an anionic or nonionic, linear, branched or crosslinked organic polymer. Detailed description of the invention

[0009] The present invention relates to the technical field of conditioning agents used in particular to block water ingress or to locally retain certain active molecules, such as fertilizers, during their dissolution in the presence of water (irrigation, rain, etc.) and thus prevent their leaching into the soil or to dry sludge. The hydro-expandable liquid composition of the invention is in the form of a dispersion comprising at least 10% and up to 40% by weight of a superabsorbent polymer in powder form, in an inverse emulsion previously distilled from an anionic or nonionic, linear, branched, or cross-linked organic polymer.

[0010] An object of the invention is to propose new hydro-expandable compositions in the form of a dispersion of a powder in an oil phase (organic and / or mineral) having a high content of superabsorbent polymer and being extremely efficient and stable, namely insensitive to any phenomenon of decantation (separation of the powder and the oil resulting in a non-homogeneous mixture).

[0011] The present invention therefore relates to a new hydro-expandable composition comprising - at least 10% and up to 40% by weight relative to the total weight of the composition obtained of a superabsorbent polymer in powder form - and 60% to 90% of an oily phase and characterized in that the oily phase comprises a previously distilled inverse emulsion of an anionic or non-ionic, linear, branched or crosslinked organic polymer.

[0012] Hydro-expandable compositions are made by mixing at least one superabsorbent polymer with a previously distilled inverse emulsion of an anionic or non-ionic, linear, branched or crosslinked organic polymer.

[0013] In the context of the present invention, a distilled inverse emulsion is in the form of a linear, branched or crosslinked anionic or nonionic organic polymer dispersion in the form of (solid) particles, comprising between 40 and 60% by weight of polymer particles, less than 10% by weight of water, preferably less than 5%, and at least one hydrocarbon solvent and is characterized in that this dispersion is obtained by distillation of an inverse emulsion.

[0014] A water-in-oil emulsion, also called inverse, consists of a mixture of 2 liquids immiscible with each other in the presence of surfactants, a continuous oily phase and a discontinuous aqueous phase (i.e. dispersed in droplets) comprising the organic polymer.

[0015] As is well known to those skilled in the art, in order to evaporate the water and the lighter fractions of the oil, the inverse polymer emulsion is heated (generally to 90°C) in a reduced-pressure atmosphere (100 millibars). A polymer dispersion is thus obtained. This dispersion contains less than 10% water.

[0016] The present invention also relates to the use of the new hydro-expandable liquid composition in particular - for sealing cables (network, electrical, control) - to prevent the leaching into soils of products either with high added value, such as fertilizers, - or to dry sludge.

[0017] In the context of fertilizers, this new composition can be applied in the formulation for example - in the mass of powder of the compounds before compaction or - as a spray in the granulation trays or - in bulk as a surface spray.

[0018] In practice, the superabsorbent polymer used is a water-retaining agent of natural or synthetic origin that has a water retention capacity greater than or equal to 30 times its weight in demineralized water, preferably greater than or equal to 50 times, advantageously greater than or equal to 100 times. This type of polymer is generally known by the abbreviation: SAP ("superabsorbent polymer"). It is generally in powder form, agglomerated or not. Its structure, based on a three-dimensional network resembling a multitude of small cavities, each capable of deforming and absorbing water, gives it the property of absorbing very large quantities of water and thus swelling. - Superabsorbent polymers of natural origin, usable within the framework of the present invention, are for example those described in patents US358364, US1693890, US3846404, US3935099 or US3661815... Examples include, but are not limited to: guar gum, alginates, carboxymethyl cellulose, dextran, xanthan gum... - Synthetic SAPs usable within the framework of the present invention are, for example, crosslinked or crosslinkable water-soluble polymers. Many types exist. Such polymers are described, for example, in French patent FR 2559158, which describes crosslinked polymers of acrylic or methacrylic acid, crosslinked grafted copolymers of the polysaccharide / acrylic or methacrylic acid type, crosslinked terpolymers of the acrylic or methacrylic acid / acrylamide / sulfonated acrylamide type, and their alkaline earth or alkali metal salts. In a preferred embodiment, the monomers used for preparing the superabsorbent polymers are selected from racrylamide and / or partially or totally salified acrylic acid and / or partially or totally salified ATBS (acrylamido tert-butylsulfonate) and / or NVP (N-vinylpyrrolidone) and / or acryloylmorpholine and / or partially or totally salified itaconic acid. In a preferred embodiment, the superabsorbent polymers are anionic crosslinked homopolymers or copolymers based on partially or totally salified acrylic acid. Other hydrophilic monomers, such as cationic monomers, as well as hydrophobic monomers, can be used to produce superabsorbent polymers. Examples of cationic monomers include diallyldialkyl ammonium salts and dialkylaminoalkyl (meth)acrylate and dialkylaminoalkyl (meth)acrylamide monomers, as well as their quaternary ammonium or acid salts. Specifically, quaternary or salified dimethylaminoethyl acrylate (ADAME) and / or dimethylaminoethyl methacrylate (MADAME), acrylamidopropyltrimethylammonium chloride (APTAC), and / or methacrylamidopropyltrimethylammonium chloride (MAPTAC) are examples. - Synthetic superabsorbent polymers are generally crosslinked with 100 to 6000 ppm of at least one crosslinking agent chosen from the group including acrylic compounds such as methylene bis acrylamide, allylic compounds such as tetra-allylammonium chloride, vinyl compounds such as divinyl benzene, diepoxy compounds, metallic salts... Some may also have double crosslinking such as with an acrylic crosslinker.

[0019] For cost reasons, synthetic superabsorbent polymers of the crosslinked sodium polyacrylate type will be preferred.

[0020] SAP can be obtained by all polymerization techniques well known to those skilled in the art: gel polymerization, precipitation polymerization, emulsion polymerization (aqueous or reverse) followed or not by a distillation step, suspension polymerization, solution polymerization, these polymerizations being followed or not by a step allowing isolation of a dry form of the (co)polymer by all types of means well known to those skilled in the art.

[0021] According to the invention, the superabsorbent polymers can be post-crosslinked on the surface, namely that they: - result from the polymerization with partial crosslinking of water-soluble ethylenically unsaturated monomers comprising at least one carboxylic function, in particular acrylic and methacrylic acids and their alkali salts, whether obtained by a polymerization process in solution, in bulk or in reverse suspension, such as described for example in patent applications EP312952, EP441507 or EP742231... - and exhibit cross-linking on the exterior of the polymer grains. This surface cross-linking is called post-cross-linking because it occurs on the SAP powder after polymerization is complete and the SAP is partially dehydrated, during drying. Post-cross-linking allows the formation of a highly cross-linked shell around the SAP particles. The SAP particles then exhibit a "core-shell" structure.

[0022] The post-crosslinking steps of hydrophilic polymers possessing carboxylic and / or carboxylate groups with a polyfunctional agent are well known to those skilled in the art. The dry powder is typically post-crosslinked by reacting it with other crosslinking agents such as, for example, organic crosslinking agents and / or multivalent cations, to produce a surface layer that is more strongly crosslinked compared to the interior of the particles. Commonly used processes for surface post-crosslinking include a step of contacting the base polymer with a surface post-crosslinking agent followed by a subsequent heat treatment step. This latter step is intended to complete the surface post-crosslinking, the heat treatment generally being carried out hot, usually using continuous dryers. Examples include documents GB 2126591, EP789048, FR2923830...Many molecules described in the literature are capable of reacting quickly enough with the carboxyl groups of superabsorbent polymers (SAPs) to bridge the polymer chains. A well-known method involves post-treating the base superabsorbent polymer. This is done by subjecting the dried powder of the base superabsorbent polymer to additional cross-linking on a surface layer of its particles through a surface post-cross-linking step. This surface post-cross-linking increases the cross-linking density on the surface of the superabsorbent polymer particles, thereby reducing the absorption capacity of the superabsorbent polymer in the surface layer.

[0023] The invention will advantageously be implemented with superabsorbent polymer particles of spherical or non-spherical shape and whose average diameter is generally between 5 pm and 500 pm and preferably between 50 and 300 pm.

[0024] In practice, the oily phase constituting one of the 2 essential elements of the composition according to the invention comprises a previously distilled reverse emulsion of an anionic or nonionic, linear, branched, or crosslinked organic polymer. Said organic polymer was obtained by reverse emulsion polymerization, water in oil, of at least one monomer selected from: - Nonionic monomers: water-soluble vinyl monomers. Preferred monomers in this class include acrylamide and methacrylamide, acrylamide derivatives such as N-alkylacrylamide (e.g., N-isopropylacrylamide, N-tert-butylacrylamide, octylacrylamide), and N,N-dialkylacrylamides such as NN-dimethylacrylamide and N-methylolacrylamide. Vinylformamide, N-vinylpyridine, N-vinylpyrrolidone, hydroxyalkyl acrylates, and methacrylates can also be used. Acrylamide is a preferred nonionic vinyl monomer. - and / or anionic monomers exhibiting acrylic, vinyl, maleic, fumaric, or allylic functionalities and containing a carboxy, phosphonate, sulfonate, or other anionically charged group, or the corresponding ammonium, alkali earth, or alkali metal salt of such a monomer. These include acrylic acid, methacrylic acid, acrylamidomethylpropanesulfonic acid, acrylamidomethylbutanoic acid, maleic acid, fumaric acid, itaconic acid, vinylsulfonic acid, styrene sulfonic acid, vinylphosphonic acid, allylsulfonic acid, allylphosphonic acid, and their water-soluble salts of an alkali metal, an alkali earth metal, and ammonium. - And possibly a branching and / or crosslinking agent.

[0025] As is well known to those skilled in the art, the inverse emulsion of an anionic or nonionic, linear, branched or crosslinked organic polymer is prepared by radical polymerization - of 15% and 40% by weight of one (or a mixture of) monomer(s) previously mentioned - between 20 and 60% by weight of water - and at least one hydrocarbon solvent as well as surfactants, the percentages being expressed by weight relative to the weight of the emulsion.

[0026] The resulting inverse emulsion of an anionic or nonionic, linear, branched, or cross-linked organic polymer is then distilled to evaporate the water and the lighter fractions of the oil. To do this, the polymer inverse emulsion is heated (generally to 90°C) in a reduced-pressure atmosphere (100 millibars). This produces a polymer dispersion in an oil phase. This dispersion contains less than 10% water. The superabsorbent polymer powder is then added to this polymer dispersion while stirring to obtain the composition of the invention having a high content of superabsorbent polymer, namely at least 10% and up to 40% by weight relative to the total weight of the composition.

[0027] Contrary to what might have been anticipated given the residual presence of water in the distilled emulsion, the dispersions of the invention are extremely stable and effective. These compositions—at least 10% and up to 40% by weight relative to the total weight of the composition obtained from a superabsorbent polymer in powder form—are made with a previously distilled inverse emulsion of an anionic or nonionic, linear, branched, or crosslinked organic polymer.

[0028] The presence of a second anionic or nonionic, linear, branched, or cross-linked organic polymer, obtained in the form of a distilled inverse emulsion, appears, for reasons that cannot be explained, to have a beneficial effect on the composition of the invention, not only by making it more stable (less sensitive to settling) but also by improving the properties of the superabsorbent. There is therefore a genuine and unexpected synergy between the two ingredients in the liquid composition of the invention.

[0029] The present invention also relates to any variant or adaptation which will become clear to a person skilled in the art, if necessary by resorting to some routine trials. Examples

[0030] To test the properties of the new compositions prepared according to the invention, trials were carried out on the soilless cultivation of tomato plants for 4 months. The aim here is to observe whether these compositions prevent / limit the leaching of fertilizers into the soil, thus allowing for better availability to the plant.

[0031] Chemical nature of the ingredients used: a. Distilled emulsion - Aprodev D01: Sodium acrylate-acrylamide copolymer - 30% anionic presented as a dispersion comprising 50% by weight of said copolymer, 5% by weight of water, the remainder being composed of an oil of mineral origin and surfactants. - Aprodev D02: Crosslinked sodium acrylate-acrylamide copolymer - 30% anionic presented as a dispersion comprising 50% by weight of said copolymer, 5% by weight of water, the remainder being composed of a mineral oil and surfactants.

[0032] b) SAP powder (average particle size: 150 pm) - Apromud GP150XL: Sodium polyacrylate - 100% anionic - Apromud P150: Sodium polyacrylate - 100% anionic

[0033] A quantity of superabsorbent polymer powder is added under stirring to the distilled emulsion in order to obtain the tested compositions of the invention. These The compositions are then added, under agitation, to a 15 / 15 / 15 NPK fertilizer formulation (composition / fertilizer ratio: 2 / 98 by weight) before compaction to form fertilizer granules. All comparative trials were conducted under strictly identical conditions using tomato seedlings (cherry tomato variety). The aim was to observe the growth of tomato plants in open ground within a greenhouse. Each condition was replicated 10 times, and the results presented are an average of the measurements taken.

[0034] The trials were conducted in a greenhouse after transplanting cherry tomato seedlings according to the following protocol: - Add a single application of fertilizer granules to the soil surface on the first day, spreading them evenly at a rate of 33g / m2 - Water every 3 days at a rate of 10 litres per m2

[0035] The variation in the mass of the raw material is expressed as a percentage relative to the control sample. This percentage is calculated using the formula (M - Mcontrol) / Mcontrol x 100

[0036] [Tables 1] Distilled Emulsion Superabsorbent Polymer (SAP) Weight Ratio Distilled Emulsion / SAP Sample Control Raw Material Variation Control Fertilizer 1 None P150 NA NA NA Control Fertilizer 2 None P150 XL NA NA NA Control Fertilizer 3 Aprodev D01 None NA NA NA Exl Aprodev D01 Apromud P150 100 / 40 Control 1 +28% EX2 Aprodev D01 Apromud P150 XL 100 / 40 Control 2 +26% EX3 Aprodev D02 Apromud P150 100 / 30 Control 1 +22% EX4 Aprodev D02 Apromud P150 XL 100 / 30 Control 2 +19% EX5 Aprodev D01 Apromud P150 100 / 40 Control 3 + 20% EX5 Aprodev D01 Apromud P150 XL 100 / 40 Control 3 + 19%

[0037] The examples described in Table 1 (annotated Ex) show that fertilizers made with the compositions of the invention significantly promote the development of tomato plants. A true and unexpected synergy is observed between the two ingredients present in the liquid composition of the invention.

[0038] Furthermore, it has been observed that, despite their very high polymer content (that of the distilled emulsion + the SAP), the hydro-expandable liquid compositions of the invention are insensitive to decantation and appear very stable while remaining pumpable.

Claims

Demands

1. Hydro-expandable composition comprising - at least 10% and up to 40% by weight relative to the total weight of the composition obtained of a superabsorbent polymer in powder form - and 60% to 90% of an oily phase and characterized in that the oily phase comprises a previously distilled inverse emulsion of an anionic or non-ionic, linear, branched or crosslinked organic polymer.

2. Hydro-expandable composition according to claim 1 in which said superabsorbent polymer in powder form has an average diameter of between 5 pm and 500 pm and preferably between 50 and 300 pm.

3. Hydro-expandable composition according to any one of claims 1 or 2 wherein said superabsorbent polymer is a homopolymer or a crosslinked synthetic copolymer comprising partially or totally salified acrylic acid, of the crosslinked sodium polyacrylate type.

4. Hydro-expandable composition according to any one of the preceding claims wherein a previously distilled reverse emulsion comprises an anionic organic polymer.

5. Use of the composition according to any one of claims 1 to 4 for the drying of sludge.

6. Use of the composition according to any one of claims 1 to 4 for sealing cables: network, electrical, control.

7. Use of the composition according to any one of claims 1 to 4 applied in the formulation of fertilizers to limit their leaching into the soil.

8. A method for manufacturing the hydro-expandable composition according to any one of claims 1 to 4, characterized in that said superabsorbent polymer in powder form is added under stirring to an oily phase, characterized in that the oily phase comprises a previously distilled inverse emulsion of an anionic or non-ionic, linear, branched or crosslinked organic polymer.