EP-4737422-A1 - EXPANDED MICROSPHERES FORMULATION

Abstract

The present disclosure relates to a composition comprising thermally expanded microspheres suspended in a non-Newtonian fluid, and the use of said composition for water-based applications, such as emulsion explosives, paint, water based coatings, coatings for thermal printing paper and other, porous ceramics, gypsum board, modelling clay, crack fillers, and cementitious compositions.

Inventors

• SVENSSON, Per Olov Fredrik
• AJDÉN, Per Erik

Assignees

• Nouryon Chemicals International B.V.

Dates

Publication Date

20260506

Application Date

20251016

Claims (14)

1. A composition comprising thermally expanded microspheres suspended in a non-Newtonian fluid, wherein the composition has a solids content of about 0.5-20 wt.%, relative to the total weight of the composition.
2. The composition of claim 1, wherein the non-Newtonian fluid is a liquid comprising a non-Newtonian thickener.
3. The composition of claim 2, wherein the liquid is a water-based liquid, an organic liquid, an inorganic liquid, or combinations thereof.
4. The composition of claims 2 or 3, wherein the non-Newtonian thickener is a polysaccharide.
5. The composition of claim 4, wherein the polysaccharide is a diutan gum, a xanthan gum, a cellulose gum, a carrageenan, or combinations thereof.
6. The composition of claims 4 or 5, wherein the polysaccharide is a diutan gum.
7. The composition of any one of claims 1 to 6, wherein the composition further comprises a biocide.
8. The composition of any one of claims 1 to 7, wherein the thermally expanded microspheres comprise a polymeric shell encapsulating a hollow core, wherein the hollow core optionally comprises a blowing agent.
9. The composition of claim 8, wherein the polymeric shell comprises or consists of one or more thermoplastic polymers.
10. The composition of claim 9, wherein the one or more thermoplastic polymers is selected from polymers obtained by polymerizing one or more vinyl monomers, lignins, polysaccharides, polysaccharide derivatives, polyesters, polyethers, polyacids, polyols, polyalkenes, polyanhydrides, or any combination thereof.
11. The composition of any one of claims 2-10, wherein the thickener is present in an amount of about 0.01-10 wt.% relative to the total weight of the non-Newtonian fluid.
12. The composition of any one of claims 1-11, wherein the composition has a solids content of about 1-10 wt.%, relative to the total weight of the composition.
13. Use of a composition according to any one of claims 1-12 for water-based applications.
14. The use of claim 13, wherein the water-based applications include emulsion explosives, paint, water based coatings, coatings for thermal printing paper and other, porous ceramics, gypsum board, modelling clay, crack fillers, and cementitious compositions.

Description

Technical Field The present disclosure relates to a composition comprising thermally expanded microspheres suspended in a non-Newtonian fluid, and the use of said composition in water-based applications, such as for sensitizing emulsion explosives, paint, water based coatings, coatings for thermal printing paper and other, porous ceramics, gypsum board, modelling clay, crack fillers, and cementitious compositions. Background Thermally expandable microspheres are known in the art and described in detail in, for example, US Patent No. 3615972. Various grades of expandable microsphere, having different expansion temperature, are commercially available from Nouryon under the trademark Expancel™, both as dry free flowing microspheres and as an aqueous slurry of microspheres. Thermally expandable microspheres typically comprise a blowing agent encapsulated within a thermoplastic shell. Upon heating, the blowing agent evaporates to increase the internal pressure, at the same time as the shell softens, resulting in significant expansion of the microspheres, normally from 2 to 5 times their diameter. Thermoplastic microspheres can be used in various applications as unexpanded or expanded. Examples of products where dry (essentially water free) expanded microspheres are used are as sensitizer in emulsion explosives and as light weight filler in solvent based paints and various thermosetting materials such as cultured marble, polyester putty and artificial wood. In many products, such as water based paints and coatings, thermal printing papers, porous ceramics and emulsion explosives, slurries (i.e., liquid suspensions) of expanded microspheres are used. A significant issue with the use of slurries of expanded microspheres in many applications, however, is slurry stability. It has been found that slurries of the expanded microspheres (prior to use in subsequent applications), which usually have a low final solids content of around 0.5-20 wt.% (typically around 1-10 wt.%), tend to be unstable (which is not typically a problem observed for equivalent slurries of unexpanded microspheres), hence there is generally a limited operating window between slurry formation and subsequent use in applications (usually in the region of a few minutes to a few hours, depending on the type of expanded microsphere, before the slurry becomes too unstable to be successfully used in the intended application). The same stability issue for expanded microspheres is not typically observed in the final application product (e.g., water based paints and coatings, thermal printing papers, porous ceramics, emulsion explosives, etc.) likely due to the presence of application-specific stabilizers/binders/matrices/etc. and/or the substantial increase in solids content in the application product formulation, In view of this, slurries of expanded microspheres generally need to be produced on-site using specialist equipment and then used immediately. It would be preferable to find a solution to this slurry instability issue, such that said pre-application slurry of expanded microspheres could be produced off-site (e.g., at a single production facility) and transported to the place of application. Description The inventors have found a highly effective solution to this issue: use a non-Newtonian fluid to suspend the expanded microspheres. To the best of the inventors' knowledge, to date slurries of expanded microspheres have always used a Newtonian liquid to suspend the expanded microspheres (e.g., water, or water comprising an additive (e.g., a thickener) that yields a Newtonian solution, such as a Newtonian starch solution). By using non-Newtonian fluids (e.g., shear-thinning liquids) instead of Newtonian fluids, the resulting slurries were found to be surprisingly stable (i.e., stable for months). Accordingly, in a first aspect, the present disclosure relates to a composition comprising thermally expanded microspheres suspended in a non-Newtonian fluid. A non-Newtonian fluid is a fluid that does not follow Newton's law of viscosity, i.e., it has variable viscosity dependent on stress (e.g., viscosity varies in response to application of shear). Conversely, a Newtonian fluid is a fluid in which viscosity is independent of the shear rate. A non-Newtonian fluid that has a reduced viscosity in response to application of shear is known as a "shear-thinning fluid". Shear-thinning liquids are the preferred non-Newtonian fluids of the present disclosure. The non-Newtonian fluid is preferably a liquid comprising a non-Newtonian thickener. As used herein, the term "non-Newtonian thickener" means a thickener that, when dissolved in a liquid, yields a non-Newtonian fluid, preferably a shear-thinning fluid. The liquid is not considered to be a limiting factor, hence the liquid may be a water-based liquid, an organic liquid, an inorganic liquid, or combinations thereof. For example, the non-Newtonian fluid may be an aqueous solution of a water-soluble non-Newtonian