Polystyrene polymer formulation

Abstract

The present invention relates to a polystyrene polymer formulation comprising a polystyrene comprising polymer material and from > 3 to 15 wt.-%, based on the total weight of the formulation, of at least one nucleating agent selected from the group consisting of a particulate earth alkali carbonate- comprising material, a particulate earth alkali phosphate-comprising material, a particulate hydroxide- comprising material and mixtures thereof, a polystyrene foam, a process for preparing the polystyrene polymer formulation and a process for preparing the polystyrene foam, an article comprising the polystyrene foam as well as the use of a particulate earth alkali carbonate-comprising material, a particulate earth alkali phosphate-comprising material, a particulate hydroxide-comprising material and mixtures thereof as nucleating agent in a polystyrene polymer formulation.

Description

[0001] Polystyrene polymer formulation

[0002] The present invention relates to a polystyrene polymer formulation comprising a polystyrene comprising polymer material and from > 3 to 15 wt.-%, based on the total weight of the formulation, of at least one nucleating agent selected from the group consisting of a particulate earth alkali carbonate- comprising material, a particulate earth alkali phosphate-comprising material, a particulate hydroxide- comprising material and mixtures thereof, a polystyrene foam, a process for preparing the polystyrene polymer formulation and a process for preparing the polystyrene foam, an article comprising the polystyrene foam as well as the use of a particulate earth alkali carbonate-comprising material, a particulate earth alkali phosphate-comprising material, a particulate hydroxide-comprising material and mixtures thereof as nucleating agent in a polystyrene polymer formulation.

[0003] The use of particulate materials such as talc or calcium carbonate as nucleating agent in polystyrene foams is known in the art. For example, the article of Demirta§, E, Ozkan H, Nofar M. “Extrusion Foaming of High Impact Polystyrene: Effects of Processing Parameters and Materials Composition”, Int J Mater Sci Res. 2018; 1 (1): 9-15, refers to the extrusion foaming behavior of high impact polystyrene (HIPS) through a twin-screw extruder using two various types of chemical blowing agents (CBA) with different inorganic fillers such as micro-lamellar talc and talc, at three different contents of 1 , 2, and 3 wt.-%. CN103450574 A refers to a composition for preparing polystyrene sheets, characterized in that the composition is mainly composed of the following parts by weight: polystyrene 10-15, rubber 1-2, degradation additives 5-7, titanium dioxide 0.3-0.5.

[0004] However, the use of talc as nucleating agent in these compositions is limited by its amount because at higher amounts the mechanical properties of the foam are becoming worse, i.e. usually the foams become too brittle. In view of this, also calcium carbonates are typically used in low amounts of about 1 to 2 wt.-% as nucleating agent in polystyrene polymer formulations.

[0005] In view of the foregoing, there is an ongoing need for polystyrene polymer formulations providing excellent mechanical properties and pore structure to the polystyrene foam prepared therefrom.

[0006] Accordingly, it is an object of the present invention to provide a polystyrene polymer formulation suitable for preparing a polystyrene foam, especially a XPS foam or an EPS foam. Furthermore, it is desirable to provide a polystyrene polymer formulation that imparts excellent mechanical properties, and especially mechanical compression strength, to the polystyrene foam prepared therefrom when keeping the foam density on comparable level. Furthermore, it is desirable to provide a polystyrene polymer formulation that imparts excellent pore structure to the polystyrene foam prepared therefrom.

[0007] The foregoing and other objects are solved by the subject-matter as defined in the independent claims. Advantageous embodiments of the present invention are defined in the corresponding subclaims.

[0008] According to one aspect of the present invention, a polystyrene polymer formulation comprising a polystyrene comprising polymer material and from > 3 to 15 wt.-%, based on the total weight of the formulation, of at least one nucleating agent selected from the group consisting of a particulate earth alkali carbonate-comprising material, a particulate earth alkali phosphate-comprising material, a particulate hydroxide-comprising material and mixtures thereof, is provided.

[0009] It has surprisingly been found out by the inventors that at least one nucleating agent selected from the group consisting of a particulate earth alkali carbonate-comprising material, a particulate earth alkali phosphate-comprising material, a particulate hydroxide-comprising material and mixtures thereof can be used in amounts of > 3 to 15 wt.-%, based on the total weight of the formulation, in a polystyrene polymer formulation without worsening the mechanical properties of the resulting foam when keeping the foam density on comparable level. Especially, such a polystyrene polymer formulation imparts excellent mechanical properties such as mechanical compression strength to the polystyrene foam prepared therefrom. In addition thereto, such a polystyrene polymer formulation imparts excellent pore structure to the polystyrene foam prepared therefrom.

[0010] According to one embodiment, the at least one nucleating agent is selected from the group consisting of natural ground calcium carbonate, precipitated calcium carbonate, surface-modified calcium carbonate, apatite, magnesium carbonate, hydromagnesite, dolomite, brucite, precipitated magnesium hydroxide, aluminium hydroxide and mixtures thereof, preferably natural ground calcium carbonate, precipitated calcium carbonate and mixtures thereof, and most preferably natural ground calcium carbonate.

[0011] According to another embodiment, the at least one nucleating agent has a weight median particle size cfeo value, measured by the sedimentation method, ranging from 0.3 to 5.5 pm, preferably from 0.5 to 4.0 pm and most preferably from 0.7 to 3.5 pm.

[0012] According to yet another embodiment, the formulation comprises the at least one nucleating agent in an amount ranging from > 3 to 10 wt.-%, preferably from 4 to 10 wt.-% based on the total weight of the formulation.

[0013] According to one embodiment, the at least one nucleating agent is treated with at least one surface-treatment agent selected from the group consisting of

[0014] I) a phosphoric acid ester blend of one or more phosphoric acid mono ester and / or salts thereof and / or one or more phosphoric acid di-ester and / or salts thereof, and / or

[0015] II) at least one saturated or unsaturated aliphatic linear or branched carboxylic acid and / or salts thereof, preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C4 to C24 and / or a salt thereof, more preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C12 to C20 and / or a salt thereof, most preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C16 to C18 and / or a salt thereof and / or

[0016] III) at least one mono-substituted succinic anhydride consisting of succinic anhydride mono-substituted with a group selected from a linear, branched, aliphatic and cyclic group having a total amount of carbon atoms from at least C2 to C30 in the substituent and / or salts thereof, and / or

[0017] IV) at least one polydialkylsiloxane, and

[0018] V) mixtures of one or more materials according to I) to IV).

[0019] According to another embodiment, the entirety of the polymer material consists of polystyrene.

[0020] According to yet another embodiment, the polymer formulation further comprises one or more additives selected from the group comprising crosslinking agents, colouring pigments, filler, fibers, dyes, waxes, lubricants, oxidative- and / or UV-stabilizers, adhesion promoter, antioxidants, process stabilizers, flame retardants, anti-dripping agents, blowing agents, processing aids and mixtures thereof.

[0021] According to one embodiment, the polymer formulation is a foam formulation.

[0022] According to a further aspect of the present invention, a polystyrene foam comprising a polystyrene comprising polymer material and from > 3 to 15 wt.-%, based on the total weight of the formulation, of at least one nucleating agent selected from the group consisting of a particulate earth alkali carbonate-comprising material, a particulate earth alkali phosphate-comprising material and mixtures thereof is provided.

[0023] According to one embodiment, the foam has a density from 15 to 100 g / l, and / or a mechanical compression strength at 10% compression force, determined according to ISO EN 826, from 50 to 1000 N, and / or a median pore circumference, measured by light microscopy, from 150 to 2000 pm.

[0024] According to another embodiment, the foam is a XPS foam or an EPS foam.

[0025] According to yet another embodiment, the foam is obtained by foaming the polystyrene polymer formulation defined herein.

[0026] According to another aspect of the present invention, a process for preparing a polystyrene polymer formulation as defined herein is provided, wherein the process comprises the steps of a) providing a polystyrene comprising polymer material, b) providing from > 3 to 15 wt.-%, based on the total weight of the formulation, of at least one nucleating agent selected from the group consisting of a particulate earth alkali carbonate- comprising material, a particulate earth alkali phosphate-comprising material and mixtures thereof, and c) contacting the components of step a) and step b) and optional additives in any order such that a polystyrene polymer formulation is formed.

[0027] According to still another aspect of the present invention, a process for preparing a polystyrene foam as defined herein is provided, wherein the process comprises the steps of i) providing the polystyrene polymer formulation defined herein, and ii) foaming the formulation of step i) such that a foam is formed.

[0028] According to a further aspect of the present invention, an article, preferably thermal insulation boards, acoustic insulation boards and packaging, comprising a polystyrene foam as defined herein is provided.

[0029] According to another aspect of the present invention, the use of a particulate earth alkali carbonate-comprising material, a particulate earth alkali phosphate-comprising material, a particulate hydroxide-comprising material and mixtures thereof as nucleating agent in a polystyrene polymer formulation, wherein the at least one nucleating agent is present in an amount from > 3 to 15 wt.-%, based on the total weight of the formulation, is provided.

[0030] It should be understood that for the purpose of the present invention, the following terms have the following meaning:

[0031] Where an indefinite or definite article is used when referring to a singular noun, e.g., “a”, “an” or “the”, this includes a plural of that noun unless anything else is specifically stated. Where the term “comprising” is used in the present description and claims, it does not exclude other elements. For the purposes of the present invention, the term “consisting of’ is considered to be a preferred embodiment of the term “comprising”. If hereinafter a group is defined to comprise at least a certain number of embodiments, this is also to be understood to disclose a group, which preferably consists only of these embodiments.

[0032] Terms like “obtainable” or “definable” and “obtained” or “defined” are used interchangeably. This, for example, means that, unless the context clearly dictates otherwise, the term “obtained” does not mean to indicate that, for example, an embodiment must be obtained by, for example, the sequence of steps following the term “obtained” though such a limited understanding is always included by the terms “obtained” or “defined” as a preferred embodiment.

[0033] Whenever the terms “including” or “having” are used, these terms are meant to be equivalent to “comprising” as defined hereinabove.

[0034] The polystyrene polymer formulation of the present invention comprises a polystyrene comprising polymer material and from > 3 to 15 wt.-%, based on the total weight of the formulation, of at least one nucleating agent selected from the group consisting of a particulate earth alkali carbonate- comprising material, a particulate earth alkali phosphate-comprising material, a particulate hydroxide- comprising material and mixtures thereof.

[0035] In the following, preferred embodiments of the inventive products will be set out in more detail. It is to be understood that these embodiments and details also apply to the inventive methods fortheir preparation and their uses described herein.

[0036] Polystyrene polymer formulation

[0037] The polystyrene polymer formulation comprises a polystyrene comprising polymer material and from > 3 to 15 wt.-%, based on the total weight of the formulation, of at least one nucleating agent selected from the group consisting of a particulate earth alkali carbonate-comprising material, a particulate earth alkali phosphate-comprising material, a particulate hydroxide-comprising material and mixtures thereof.

[0038] It is appreciated that a variety of thermoplastic homopolymers, copolymers and polymer blends can contain the at least one nucleating agent. These polymers are derived from one or more alkenyl aromatic compounds, including styrene, alpha-methylstyrene, nuclear methylstyrenes, nuclear ethylstyrenes, nuclear vinylxylenes, nuclear chlorostyrenes and nuclear bromostyrenes, with minor amounts of other readily polymerizable compounds such as butadiene or polybutadiene, alkyl methacrylates, alkyl acrylates, acrylonitrile, maleic anhydride and rubber reinforced (either natural or synthetic) styrene polymers. For the purpose of convenience, these polymers, copolymers, interpolymers and polymer blends are referred to as "polystyrene comprising polymer material" and comprise in chemically combined form, at least 60 wt.-% of at least one alkenyl aromatic compound, preferably styrene. Preferably, the polystyrene comprising polymer material comprises in chemically combined form, at least 80 wt.-% of at least one alkenyl aromatic compound, preferably styrene.

[0039] For instance, general purpose polystyrene (GPPS) or high impact polystyrene (HIPS), or a combination of both, can be used, which are well known in the art. An example for a GPPS grade that can be used is Styrolution® PS 158N from Ineos (MVR of 3.0 cm3 / 10min, measured according to ISO 1133 at 200°C under 5 kg load), and an example for a HIPS grade is Styrolution® PS 486N from Ineos (MVR of 3.9 cm3 / 1 Omin, measured according to ISO 1133 at 200°C under 5 kg load). More preferably, the polystyrene comprising polymer material comprises in chemically combined form, at least 90 wt.-% of at least one alkenyl aromatic compound, preferably styrene. For example, the polystyrene comprising polymer material comprises in chemically combined form, at least 93 wt.-%, more preferably at least 95 wt.-% and most preferably at least 98 wt.-% of at least one alkenyl aromatic compound, preferably styrene.

[0040] In one embodiment, the entirety of the polystyrene comprising polymer material essentially consists of polystyrene. For example, the entirety of the polystyrene comprising polymer material consists of polystyrene.

[0041] The polystyrene comprising polymer material preferably has a MVR value, determined according to ISO 1133 at 200°C and 5 kg load, in the range from 0.7 to 20.0 cm3 / 1 Omin, more preferably from 1 .0 to 16.0 cm3 / 10min and most preferably from 1 .0 to 14.0 cm3 / 10min.

[0042] It is appreciated that the polystyrene polymer formulation may comprise polymer materials differing from the polystyrene comprising polymer material. In particular, the polystyrene polymer formulation may comprise acrylic co-polymer(s), e.g. with high molecular weight, as processing aid(s). Such polymer material(s), especially processing aid(s) such as acrylic co-polymer(s), differing from the polystyrene comprising polymer material can be present in an amount < 7 wt.-%, based on the total weight of the polystyrene polymer formulation. For example, if such polymer materials, especially processing aid(s) such as acrylic co-polymer(s), differing from the polystyrene comprising polymer material are present, the amounts range from 0.1 to 7 wt.-%, preferably from 0.5 to 5 wt.-%, based on the total weight of the polystyrene polymer formulation.

[0043] In one embodiment, the polystyrene polymer formulation according to this invention does not comprise (a) further polymer(s) different to the polystyrene comprising polymer material present in the formulation. Typically, if an additional polymer is present, such a polymer is a processing aid, i.e. an additive.

[0044] Accordingly in one embodiment, the polystyrene polymer formulation consists of the polystyrene comprising polymer material, the at least one nucleating agent, and the optional one or more additive(s), which might contain low amounts of acrylic co-polymer(s), e.g. with high molecular weight, as processing aid(s), e.g. in amounts ranging from 0.1 to 7 wt.-%, preferably from 0.5 to 5 wt.-%, based on the total weight of the polystyrene polymer formulation.

[0045] The polystyrene polymer formulation comprises at least one nucleating agent selected from the group consisting of a particulate earth alkali carbonate-comprising material, a particulate earth alkali phosphate-comprising material, a particulate hydroxide-comprising material and mixtures thereof.

[0046] As used herein, the term “nucleating agent” refers to an inorganic compound that induces the formation of foam cells (foam bubbles), i.e., regulate and control the foam cell structure of the resulting foam by the size and number of foam.

[0047] The at least one nucleating agent of the present invention is selected from the group consisting of a particulate earth alkali carbonate-comprising material, a particulate earth alkali phosphate-comprising material, a particulate hydroxide-comprising material and mixtures thereof. Preferably, the at least one nucleating agent is selected from the group consisting of a particulate earth alkali carbonate-comprising material and / or a particulate earth alkali phosphate- comprising material. More preferably, the at least one nucleating agent is a particulate earth alkali carbonate-comprising material.

[0048] The term “earth alkali” in the earth alkali carbonate-comprising material and in the earth alkali phosphate-comprising material in the meaning of the present invention refers to the divalent cations of the earth alkali metals, like magnesium ions, calcium ions, strontium ions or mixtures thereof, preferably magnesium ions, calcium ions or mixtures thereof, most preferably calcium ions.

[0049] The term “earth alkali carbonate-comprising material” refers to a material that comprises at least 40.0 wt.-% earth alkali carbonate, based on the total dry weight of the earth alkali carbonate- comprising material. Preferably, the material comprises at least 60.0 wt.-% and more preferably at least 80.0 wt.-% most preferably 90 to 100 wt.-% earth alkali carbonate, based on the total dry weight of the earth alkali carbonate-comprising material.

[0050] The term “earth alkali phosphate-comprising material” refers to a material that comprises 8.0 to 100 wt.-% earth alkali phosphate, based on the total dry weight of the earth alkali phosphate- comprising material. Preferably, the material comprises 20.0 to 80.0 wt.-% and more preferably 25.0 to 60.0 wt.-% earth alkali phosphate, based on the total dry weight of the earth alkali phosphate- comprising material.

[0051] The term “hydroxide-comprising material” refers to a material that comprises 8.0 to 100 wt.-% of a hydroxide compound, based on the total dry weight of the hydroxide-comprising material. Preferably, the material comprises at least 60.0 wt.-% and more preferably at least 80 wt.-% most preferably 90 to 100 wt.-% of a hydroxide compound, based on the total dry weight of the hydroxide- comprising material.

[0052] It is appreciated that the expression "at least one" nucleating agent means that one or more kind(s) of nucleating agent(s) selected from the group consisting of a particulate earth alkali carbonate-comprising material and / or a particulate earth alkali phosphate-comprising material and / or a particulate hydroxide-comprising material can be present in the polystyrene polymer formulation.

[0053] Accordingly, it should be noted that the at least one nucleating agent can be one kind of a particulate earth alkali carbonate-comprising material or a particulate earth alkali phosphate- comprising material or a particulate hydroxide-comprising material. Alternatively, the at least one nucleating agent can be a mixture of two or more kinds of particulate earth alkali carbonate-comprising material(s) and / or particulate earth alkali phosphate-comprising material(s) and / or particulate hydroxide-comprising material(s). In one embodiment, the at least one nucleating agent can be a mixture of two or three kinds of particulate earth alkali carbonate-comprising material(s) and / or particulate earth alkali phosphate-comprising material(s) and / or particulate hydroxide-comprising material(s), like two kinds of particulate earth alkali carbonate-comprising material(s) and / or particulate earth alkali phosphate-comprising material(s) and / or particulate hydroxide-comprising material(s). For example, the at least one nucleating agent is a mixture of a particulate earth alkali carbonate- comprising material and a particulate hydroxide-comprising material, e.g. a calcium carbonate- comprising material in combination with brucite, precipitated magnesium hydroxide or aluminium hydroxide. In one embodiment of the present invention, the at least one nucleating agent is one kind of a particulate earth alkali carbonate-comprising material or a particulate earth alkali phosphate- comprising material or a particulate hydroxide-comprising material.

[0054] For example, the particulate earth alkali carbonate-comprising material is a calcium carbonate- comprising material and / or a magnesium carbonate-comprising material, preferably a calcium carbonate-comprising material. Additionally or alternatively, the particulate earth alkali phosphate- comprising material is a calcium phosphate-comprising material and / or a magnesium phosphate- comprising material, preferably a calcium phosphate-comprising material. Additionally or alternatively, the particulate hydroxide-comprising material is an earth alkali hydroxide-comprising material and / or a hydroxide of the boron group-comprising material, preferably a calcium and / or magnesium hydroxide- comprising material.

[0055] In one embodiment, the at least one nucleating agent is selected from the group consisting of natural ground calcium carbonate, precipitated calcium carbonate, surface-modified calcium carbonate, apatite, magnesium carbonate, hydromagnesite, dolomite, brucite, precipitated magnesium hydroxide, aluminium hydroxide and mixtures thereof.

[0056] Thus, the at least one nucleating agent is preferably a particulate earth alkali carbonate- comprising material selected from the group comprising, more preferably consisting of, natural ground calcium carbonate, precipitated calcium carbonate, surface-modified calcium carbonate, magnesium carbonate, hydromagnesite, dolomite and mixtures thereof.

[0057] Additionally or alternatively, the at least one nucleating agent is preferably a particulate earth alkali phosphate-comprising material selected from the group comprising, more preferably consisting of, apatite.

[0058] Additionally or alternatively, the at least one nucleating agent is preferably a particulate hydroxide-comprising material selected from the group comprising, more preferably consisting of, brucite, precipitated magnesium hydroxide, aluminium hydroxide and mixtures thereof.

[0059] Preferably, the at least one nucleating agent is selected from the group consisting of natural ground calcium carbonate, precipitated calcium carbonate and mixtures thereof. Most preferably, the at least one nucleating agent is natural ground calcium carbonate.

[0060] “Natural ground calcium carbonate” (NGCC) preferably is selected from calcium carbonate containing minerals selected from the group comprising marble, chalk, limestone and mixtures thereof. Natural calcium carbonate may comprise further naturally occurring components such as magnesium carbonate, alumino silicate etc.

[0061] “Precipitated calcium carbonate” (PCC) in the meaning of the present invention is a synthesized material, generally obtained by precipitation following reaction of carbon dioxide and calcium hydroxide in an aqueous environment or by precipitation of calcium and carbonate ions, for example CaCh and Na2COs, out of solution. Further possible ways of producing PCC are the lime soda process, or the Solvay process in which PCC is a by-product of ammonia production. Precipitated calcium carbonate exists in three primary crystalline forms: calcite, aragonite and vaterite, and there are many different polymorphs (crystal habits) for each of these crystalline forms. Calcite has a trigonal structure with typical crystal habits such as scalenohedral (S-PCC), rhombohedral (R- PCC), hexagonal prismatic, pinacoidal, colloidal (C-PCC), cubic, and prismatic (P-PCC). Aragonite is an orthorhombic structure with typical crystal habits of twinned hexagonal prismatic crystals, as well as a diverse assortment of thin elongated prismatic, curved bladed, steep pyramidal, chisel shaped crystals, branching tree, and coral or worm-like form. Vaterite belongs to the hexagonal crystal system. The obtained PCC slurry can be mechanically dewatered and dried.

[0062] According to one embodiment of the present invention, the precipitated calcium carbonate is precipitated calcium carbonate, preferably comprising aragonitic, vateritic or calcitic mineralogical crystal forms or mixtures thereof.

[0063] The “surface-modified calcium carbonate” is a reaction product of natural ground calcium carbonate or precipitated calcium carbonate with carbon dioxide and one or more HsO+ion donors, wherein the carbon dioxide is formed in situ by the HsO+ion donors treatment and / or is supplied from an external source.

[0064] “Dolomite” in the meaning of the present invention is a carbonatic calcium-magnesium-mineral having the chemical composition of CaMg(CC>3)2 (“CaCCh ■ MgCCh”). Dolomite mineral contains at least 30.0 wt.-% MgCCh, based on the total weight of dolomite, preferably more than 35.0 wt.-%, more than 40.0 wt.-%, typically from 45.0 to 46.0 wt.-% MgCCh.

[0065] “Hydromagnesite” or basic magnesium carbonate, which is the standard industrial name for hydromagnesite, is a naturally occurring mineral which is found in magnesium rich minerals such as serpentine and altered magnesium rich igneous rocks, but also as an alteration product of brucite in periclase marbles. Hydromagnesite has the chemical composition of Mgs(CO3)4(OH)2 ■ 4H2O. It should be appreciated that hydromagnesite is a very specific mineral form of magnesium carbonate and occurs naturally as small needle-like crystals or crusts of acicular or bladed crystals. Besides the natural hydromagnesite, synthetic hydromagnesites (or precipitated magnesium carbonates) can be also prepared.

[0066] “Apatite” is a naturally occurring mineral and has the chemical composition of Caio(PC>4)6(OH,F,CI)2. The chemical composition of the crystal unit cell formulae of the individual minerals is Caio(P04)e(OH)2, Caio(P04)e(F)2 and Caio(P04)e(CI)2.

[0067] “Brucite” is a is a naturally occurring mineral and has the chemical composition of Mg(OH)2.

[0068] It is required that the at least one nucleating agent is a particulate material. That is to say, the at least one nucleating agent is present in form of solid particles.

[0069] It is to be noted that particulate nucleating agents and corresponding particle sizes are know to the skilled person for the products to be prepared. Depending on the specific need, the skilled person will thus adapt the particle size of the at least one nucleating agent in view of the at least one nucleating agent used and the products to be prepared.

[0070] However, the inventors found out that it may be specifically advantageous that the at least one nucleating agent has a weight median particle size cfeo value, measured by the sedimentation method, ranging from 0.3 to 5.5 pm. Preferably, the at least one nucleating agent has a weight median particle size c o value, measured by the sedimentation method, ranging from 0.5 to 4.0 pm and most preferably from 0.7 to 3.5 pm. In one embodiment, the at least one nucleating agent has a weight median particle size cfeo value, measured by the sedimentation method, ranging from 0.3 to 3.5 pm, preferably from 0.5 to 3.2 pm and most preferably from 0.7 to 3.0 pm. Additionally or alternatively, the at least one nucleating agent has a weight particle size cfos value, measured by the sedimentation method, ranging from 1 .5 to 50.0 pm. Preferably, the at least one nucleating agent has a weight particle size daa value, measured by the sedimentation method, ranging from 1 .5 to 30.0 pm and most preferably from 2.0 to 25.0 pm.

[0071] Thus, the at least one nucleating agent has a weight median particle size dso value, measured by the sedimentation method, ranging from 0.3 to 5.5 pm and a weight particle size daa value, measured by the sedimentation method, ranging from 1 .5 to 50.0 pm. Preferably, the at least one nucleating agent has a weight median particle size dso value, measured by the sedimentation method, ranging from 0.5 to 4.0 pm and a weight particle size daa value, measured by the sedimentation method, ranging from 1 .5 to 30.0 pm. Most preferably, the at least one nucleating agent has a weight median particle size dso value, measured by the sedimentation method, ranging from 0.7 to 3.5 pm and a weight particle size daa value, measured by the sedimentation method, ranging from 2.0 to 25.0 pm.

[0072] The “particle size” of particulate materials herein is described by its weight-based distribution of particle sizes dx. Therein, the value dx represents the diameter relative to which x % by weight of the particles have diameters less than dx. This means that, for example, the dgs value is the particle size at which 98 wt.-% of all particles are smaller than that particle size. The dso value is thus the weight median particle size, i.e. 50 wt.-% of all particles are smaller than this particle size. For the purpose of the present invention, the particle size is specified as weight median particle size cfeo(wt) unless indicated otherwise. Particle sizes were determined by using Sedigraph™ 5120 instrument of Micromeritics Instrument Corporation. The method and the instrument are known to the skilled person and are commonly used to determine the particle size of fillers and pigments. The measurements were carried out in an aqueous solution of 0.1 wt.-% Na4P2O?.

[0073] Additionally, the at least one nucleating agent may have a high specific surface area.

[0074] The “specific surface area” (expressed in m2 / g) of a material as used throughout the present document can be determined by the Brunauer Emmett Teller (BET) method with nitrogen as adsorbing gas and by use of a ASAP 2460 instrument from Micromeritics. The method is well known to the skilled person and defined in ISO 9277:2010. Samples are conditioned at 100 °C under vacuum for a period of 30 min prior to measurement. The total surface area (in m2) of said material can be obtained by multiplication of the specific surface area (in m2 / g) and the mass (in g) of the material.

[0075] Additionally or alternatively, the at least one nucleating agent has a specific surface area (BET) of from 1 .5 to 20 m2 / g as measured using nitrogen and the BET method according to ISO 9277:2010. For example, the at least one nucleating agent has a specific surface area (BET) of from 2.0 to 18 m2 / g as measured using nitrogen and the BET method according to ISO 9277:2010, preferably from 2.0 to 16 m2 / g, and most preferably from 2.0 to 15 m2 / g.

[0076] Additionally, it is preferred that the at least one nucleating agent has a very low residual moisture content.

[0077] Unless specified otherwise, the term “residual moisture content” refers to a process according to which at least a portion of water is removed from a material such that a constant weight of the obtained “dried” material at 105°C is reached. In general, a “dried” or “dry” material has a residual moisture content, unless specified otherwise, of less than or equal to 0.2 wt. %, based on the total dry weight of the at least one nucleating agent.

[0078] In particular, it has been found out that the at least one nucleating agent preferably has a residual moisture content of < 0.2 wt.-%, based on the total dry weight of the at least one nucleating agent. Preferably, the at least one nucleating agent has a residual moisture content of < 0.15 wt.-%, and most preferably of < 0.1 wt.-%, based on the total dry weight of the at least one nucleating agent. For example, the at least one nucleating agent has a residual moisture content ranging from 0.03 to

[0079] < 0.2 wt.-%, preferably from 0.05 to < 0.15 wt.-%, and most preferably from 0.05 to < 0.1 wt.-%, based on the total dry weight of the at least one nucleating agent.

[0080] Thus, the at least one nucleating agent preferably has i) a weight median particle size cfeo value measured by the sedimentation method from 0.3 to 5.5 pm, and ii) a specific surface area (BET) of 1 .5 to 20 m2 / g as measured using nitrogen and the BET method according to ISO 9277:2010, and iii) a residual moisture content of < 0.2 wt.-%, based on the total dry weight of the at least one nucleating agent.

[0081] In a preferred embodiment, the at least one nucleating agent has i) a weight median particle size cfeo value measured by the sedimentation method from 0.3 to 5.5 pm, preferably from 0.5 to 4.0 pm and most preferably from 0.7 to 3.5 pm, and ii) a specific surface area (BET) of 1 .5 to 20 m2 / g as measured using nitrogen and the BET method according to ISO 9277:2010, preferably from 2.0 to 18 m2 / g, more preferably from 2.0 to 16 m2 / g, and most preferably from 2.0 to 15 m2 / g, and iii) a residual moisture content of < 0.2 wt.-%, e.g. from 0.03 to < 0.2 wt.-%, preferably of

[0082] < 0.15 wt.-%, e.g. from 0.05 to < 0.15 wt.-%, and most preferably of < 0.1 wt.-%, e.g. from 0.05 to

[0083] < 0.1 wt.-%, based on the total dry weight of the at least one nucleating agent.

[0084] Additionally, the at least one nucleating agent may have a top cut (daa) measured by the sedimentation method of 1 .5 to 50.0 pm, more preferably of 1 .5 to 30.0 pm, and most preferably of 2.0 to 25.0 pm.

[0085] In one embodiment, the at least one nucleating agent thus has i) a weight median particle size dso value measured by the sedimentation method from 0.3 to 5.5 pm, preferably from 0.5 to 4.0 pm and most preferably from 0.7 to 3.5 pm, and ii) a specific surface area (BET) of 1 .5 to 20 m2 / g as measured using nitrogen and the BET method according to ISO 9277:2010, preferably from 2.0 to 18 m2 / g, more preferably from 2.0 to 16 m2 / g, and most preferably from 2.0 to 15 m2 / g, and iii) a residual moisture content of < 0.2 wt.-%, e.g. from 0.03 to < 0.2 wt.-%, preferably of

[0086] < 0.15 wt.-%, e.g. from 0.05 to < 0.15 wt.-%, and most preferably of < 0.1 wt.-%, e.g. from 0.05 to

[0087] < 0.1 wt.-%, based on the total dry weight of the at least one nucleating agent, and iv) a top cut (cfeo) measured by the sedimentation method of 1 .5 to 50.0 pm, more preferably of 1 .5 to 30.0 pm, and most preferably of 2.0 to 25.0 pm.

[0088] It is preferred that the at least one nucleating agent can be treated with at least one surfacetreatment agent and thus is preferably a surface-treated nucleating agent. In another embodiment, the at least one nucleating agent is not surface-treated with at least one surface-treatment agent and thus is an untreated nucleating agent.

[0089] A “surface-treatment agent” in the meaning of the present invention is any material, which is capable of reacting and / or forming an adduct with the surface of the at least one nucleating agent, thereby forming a surface-treatment layer on at least a part of the surface of the at least one nucleating agent. It should be understood that the present invention is not limited to any particular surface-treatment agents. The skilled person knows how to select suitable materials for use as surface-treatment agents.

[0090] The term “at least one” surface-treatment agent in the meaning of the present invention means that the surface-treatment agent comprises, preferably consists of, one or more surface-treatment agent(s).

[0091] In one embodiment of the present invention, the at least one surface-treatment agent comprises, preferably consists of, one surface-treatment agent. Alternatively, the at least one surfacetreatment agent comprises, preferably consists of, two or more surface-treatment agents. For example, the at least one surface-treatment agent comprises, preferably consists of, one surfacetreatment agent.

[0092] In one embodiment, the at least one nucleating agent is treated with at least one surfacetreatment agent, preferably one surface-treatment agent, selected from the group consisting of

[0093] I) a phosphoric acid ester blend of one or more phosphoric acid mono ester and / or salts thereof and / or one or more phosphoric acid di-ester and / or salts thereof, and / or

[0094] II) at least one saturated or unsaturated aliphatic linear or branched carboxylic acid and / or salts thereof, preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C4 to C24 and / or a salt thereof, more preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C12 to C20 and / or a salt thereof, most preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C16 to C18 and / or salts thereof and / or

[0095] III) at least one mono-substituted succinic anhydride consisting of succinic anhydride mono-substituted with a group selected from a linear, branched, aliphatic and cyclic group having a total amount of carbon atoms from at least C2 to C30 in the substituent and / or salts thereof, and / or

[0096] IV) at least one polydialkylsiloxane, and / or

[0097] V) mixtures of one or more materials according to I) to IV).

[0098] According to one embodiment of the present invention, the at least one nucleating agent is treated with at least one surface-treatment agent, which is a phosphoric acid ester blend of one or more phosphoric acid mono-ester and / or salts thereof and / or one or more phosphoric acid di-ester and / or salts thereof.

[0099] In one embodiment of the present invention, the one or more phosphoric acid mono-ester consists of an o-phosphoric acid molecule esterified with one alcohol selected from saturated, branched or linear, aliphatic or aromatic alcohols having a total amount of carbon atoms from C6 to C30 in the alcohol substituent. For example, the one or more phosphoric acid mono-ester consists of an o-phosphoric acid molecule esterified with one alcohol selected from saturated, branched or linear, aliphatic or aromatic alcohols having a total amount of carbon atoms from C8 to C22, more preferably from C8 to C20 and most preferably from C8 to C18 in the alcohol substituent.

[0100] Alkyl esters of phosphoric acid are well known in the industry especially as surfactants, lubricants and antistatic agents (Die Tenside; Kosswig und Stache, Carl Hanser Verlag Munchen, 1993).

[0101] The synthesis of alkyl esters of phosphoric acid by different methods and the surface treatment of minerals with alkyl esters of phosphoric acid are well known by the skilled person, e.g. from Pesticide Formulations and Application Systems: 15th Volume; Collins HM, Hall FR, Hopkinson M, STP1268; Published: 1996, US3897519 A, US4921990A, US4350645A, US6710199B2, US4126650A, US5554781A, EP1092000B1 and W02008023076A1 .

[0102] In one embodiment of the present invention, the one or more phosphoric acid mono-ester consists of an o-phosphoric acid molecule esterified with one alcohol selected from saturated and linear or branched and aliphatic alcohols having a total amount of carbon atoms from Ce to C30 in the alcohol substituent. For example, the one or more phosphoric acid mono-ester consists of an 0- phosphoric acid molecule esterified with one alcohol selected from saturated and linear or branched and aliphatic alcohols having a total amount of carbon atoms from C8 to C22, more preferably from C8 to C20 and most preferably from C8 to C18 in the alcohol substituent.

[0103] In one embodiment of the present invention, the one or more phosphoric acid mono-ester consists of an o-phosphoric acid molecule esterified with one alcohol selected from saturated and linear and aliphatic alcohols having a total amount of carbon atoms from C6 to C30, preferably from C8 to C22, more preferably from C8 to C20 and most preferably from C8 to C18 in the alcohol substituent. Alternatively, the one or more phosphoric acid mono-ester consists of an o-phosphoric acid molecule esterified with one alcohol selected from saturated and branched and aliphatic alcohols having a total amount of carbon atoms from C6 to C30, preferably from C8 to C22, more preferably from C8 to C20 and most preferably from C8 to C18 in the alcohol substituent.

[0104] In one embodiment of the present invention, the one or more phosphoric acid mono-ester is selected from the group comprising hexyl phosphoric acid mono-ester, heptyl phosphoric acid monoester, octyl phosphoric acid mono-ester, 2-ethylhexyl phosphoric acid mono-ester, nonyl phosphoric acid mono-ester, decyl phosphoric acid mono-ester, undecyl phosphoric acid mono-ester, dodecyl phosphoric acid mono-ester, tetradecyl phosphoric acid mono-ester, hexadecyl phosphoric acid monoester, heptylnonyl phosphoric acid mono-ester, octadecyl phosphoric acid mono-ester, 2-octyl-1- decylphosphoric acid mono-ester, 2-octyl-1 -dodecylphosphoric acid mono-ester and mixtures thereof.

[0105] For example, the one or more phosphoric acid mono-ester is selected from the group comprising 2-ethylhexyl phosphoric acid mono-ester, hexadecyl phosphoric acid mono-ester, heptylnonyl phosphoric acid mono-ester, octadecyl phosphoric acid mono-ester, 2-octyl-1- decylphosphoric acid mono-ester, 2-octyl-1 -dodecylphosphoric acid mono-ester and mixtures thereof. In one embodiment of the present invention, the one or more phosphoric acid mono-ester is 2-octyl-1- dodecylphosphoric acid mono-ester.

[0106] It is appreciated that the expression “one or more” phosphoric acid di-ester means that one or more kinds of phosphoric acid di-ester may be present in the treatment layer of the surface-treated material product and / or the phosphoric acid ester blend. Accordingly, it should be noted that the one or more phosphoric acid di-ester may be one kind of phosphoric acid di-ester. Alternatively, the one or more phosphoric acid di-ester may be a mixture of two or more kinds of phosphoric acid di-ester. For example, the one or more phosphoric acid di-ester may be a mixture of two or three kinds of phosphoric acid di-ester, like two kinds of phosphoric acid diester.

[0107] In one embodiment of the present invention, the one or more phosphoric acid di-ester consists of an o-phosphoric acid molecule esterified with two alcohols selected from saturated, branched or linear, aliphatic or aromatic alcohols having a total amount of carbon atoms from C6 to C30 in the alcohol substituent. For example, the one or more phosphoric acid di-ester consists of an o- phosphoric acid molecule esterified with two fatty alcohols selected from saturated, branched or linear, aliphatic or aromatic alcohols having a total amount of carbon atoms from C8 to C22, more preferably from C8 to C20 and most preferably from C8 to C18 in the alcohol substituent.

[0108] It is appreciated that the two alcohols used for esterifying the phosphoric acid may be independently selected from the same or different saturated, branched or linear, aliphatic or aromatic alcohols having a total amount of carbon atoms from C6 to C30 in the alcohol substituent. In other words, the one or more phosphoric acid di-ester may comprise two substituents being derived from the same alcohols or the phosphoric acid di-ester molecule may comprise two substituents being derived from different alcohols.

[0109] In one embodiment of the present invention, the one or more phosphoric acid di-ester consists of an o-phosphoric acid molecule esterified with two alcohols selected from the same or different, saturated and linear or branched and aliphatic alcohols having a total amount of carbon atoms from C6 to C30 in the alcohol substituent. For example, the one or more phosphoric acid di-ester consists of an o-phosphoric acid molecule esterified with two alcohols selected from the same or different, saturated and linear or branched and aliphatic alcohols having a total amount of carbon atoms from C8 to C22, more preferably from C8 to C20 and most preferably from C8 to C18 in the alcohol substituent.

[0110] In one embodiment of the present invention, the one or more phosphoric acid di-ester consists of an o-phosphoric acid molecule esterified with two alcohols selected from the same or different, saturated and linear and aliphatic alcohols having a total amount of carbon atoms from C6 to C30, preferably from C8 to C22, more preferably from C8 to C20 and most preferably from C8 to C18 in the alcohol substituent. Alternatively, the one or more phosphoric acid di-ester consists of an o-phosphoric acid molecule esterified with two alcohols selected from the same or different, saturated and branched and aliphatic alcohols having a total amount of carbon atoms from C6 to C30, preferably from C8 to C22, more preferably from C8 to C20 and most preferably from C8 to C18 in the alcohol substituent.

[0111] In one embodiment of the present invention, the one or more phosphoric acid di-ester is selected from the group comprising hexyl phosphoric acid di-ester, heptyl phosphoric acid di-ester, octyl phosphoric acid di-ester, 2-ethylhexyl phosphoric acid di-ester, nonyl phosphoric acid di-ester, decyl phosphoric acid di-ester, undecyl phosphoric acid di-ester, dodecyl phosphoric acid di-ester, tetradecyl phosphoric acid di-ester, hexadecyl phosphoric acid di-ester, heptylnonyl phosphoric acid di-ester, octadecyl phosphoric acid di-ester, 2-octyl-1 -decylphosphoric acid di-ester, 2-octyl-1- dodecylphosphoric acid di-ester and mixtures thereof. For example, the one or more phosphoric acid di-ester is selected from the group comprising 2-ethylhexyl phosphoric acid di-ester, hexadecyl phosphoric acid di-ester, heptylnonyl phosphoric acid di-ester, octadecyl phosphoric acid di-ester, 2-octyl-1 -decylphosphoric acid di-ester, 2-octyl-1- dodecylphosphoric acid di-ester and mixtures thereof. In one embodiment of the present invention, the one or more phosphoric acid di-ester is 2-octyl-1 -dodecylphosphoric acid di-ester.

[0112] In one embodiment of the present invention, the one or more phosphoric acid mono-ester is selected from the group comprising 2-ethylhexyl phosphoric acid mono-ester, hexadecyl phosphoric acid mono-ester, heptylnonyl phosphoric acid mono-ester, octadecyl phosphoric acid mono-ester, 2- octyl-1 -decylphosphoric acid mono-ester, 2-octyl-1 -dodecylphosphoric acid mono-ester and mixtures thereof and the one or more phosphoric acid di-ester is selected from the group comprising 2- ethylhexyl phosphoric acid di-ester, hexadecyl phosphoric acid di-ester, heptylnonyl phosphoric acid di-ester, octadecyl phosphoric acid di-ester, 2-octyl-1 -decylphosphoric acid di-ester, 2-octyl-1- dodecylphosphoric acid di-ester and mixtures thereof.

[0113] According to another embodiment of the present invention, the at least one nucleating agent is treated with at least one surface-treatment agent, which is at least one saturated or unsaturated aliphatic linear or branched carboxylic acid and / or salts thereof preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C4 to C24 and / or a salt thereof, more preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C12 to C20 and / or a salt thereof, most preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C16 to C18 and / or a salt thereof.

[0114] The carboxylic acid in the meaning of the present invention may be selected from one or more linear chain, branched chain, saturated, or unsaturated and / or alicyclic carboxylic acids. Preferably, the aliphatic carboxylic acid is a monocarboxylic acid, i.e. the aliphatic carboxylic acid is characterized in that a single carboxyl group is present. Said carboxyl group is placed at the end of the carbon skeleton.

[0115] In one embodiment of the present invention, the aliphatic linear or branched carboxylic acid and / or salt thereof is selected from saturated unbranched carboxylic acids, preferably selected from the group of carboxylic acids consisting of pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid, nonadecanoic acid, arachidic acid, heneicosylic acid, behenic acid, tricosylic acid, lignoceric acid, their salts, their anhydrides and mixtures thereof.

[0116] In another embodiment of the present invention, the aliphatic linear or branched carboxylic acid and / or salt thereof is selected from the group consisting of octanoic acid, decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid and mixtures thereof. Preferably, the aliphatic carboxylic acid is selected from the group consisting of myristic acid, palmitic acid, stearic acid, their salts, their anhydrides and mixtures thereof.

[0117] Preferably, the aliphatic carboxylic acid and / or a salt or anhydride thereof is stearic acid and / or a stearic acid salt or stearic anhydride.

[0118] Alternatively, the unsaturated aliphatic linear or branched carboxylic acid is preferably selected from the group consisting of myristoleic acid, palmitoleic acid, sapienic acid, oleic acid, elaidic acid, vaccenic acid, linoleic acid, a-linolenic acid, eicosapentaenoic acid, docosahexaenoic acid and mixtures thereof. More preferably, the unsaturated aliphatic linear or branched carboxylic acid selected from the group consisting of myristoleic acid, palmitoleic acid, sapienic acid, oleic acid, elaidic acid, vaccenic acid, linoleic acid, a-linolenic acid and mixtures thereof. Most preferably, the unsaturated aliphatic linear or branched carboxylic acid is oleic acid and / or linoleic acid, preferably oleic acid or linoleic acid, most preferably linoleic acid.

[0119] Additionally or alternatively, the surface-treatment agent is a salt of an unsaturated aliphatic linear or branched carboxylic acid.

[0120] The term “salt of an unsaturated aliphatic linear or branched carboxylic acid” refers to an unsaturated fatty acid, wherein the active acid group is partially or completely neutralized. The term “partially neutralized” unsaturated aliphatic linear or branched carboxylic acid refers to a degree of neutralization of the active acid groups in the range from 40 and 95 mole-% preferably from 50 to 95 mole-%, more preferably from 60 to 95 mole-% and most preferably from 70 to 95 mole-%. The term “completely neutralized” unsaturated aliphatic linear or branched carboxylic acid refers to a degree of neutralization of the active acid groups of > 95 mole-%, preferably of > 99 mole-%, more preferably of > 99.8 mole-% and most preferably of 100 mole-%. Preferably, the active acid groups are partially or completely neutralized.

[0121] The salt of unsaturated aliphatic linear or branched carboxylic acid is preferably a compound selected from the group consisting of sodium, potassium, calcium, magnesium, lithium, strontium, primary amine, secondary amine, tertiary amine and / or ammonium salts thereof, whereby the amine salts are linear or cyclic. For example, the unsaturated aliphatic linear or branched carboxylic acid is a salt of oleic acid and / or linoleic acid, preferably oleic acid or linoleic acid, most preferably linoleic acid.

[0122] According to another embodiment of the present invention, the at least one nucleating agent is treated with at least one surface-treatment agent, which is at least one mono-substituted succinic anhydride consisting of succinic anhydride mono-substituted with a group selected from a linear, branched, aliphatic and cyclic group having a total amount of carbon atoms from at least C2 to C30 in the substituent and / or salts thereof. Preferably, the at least one nucleating agent is treated with at least one surface-treatment agent, which is at least one mono-substituted succinic anhydride consisting of succinic anhydride mono-substituted with a group being a linear aliphatic group having a total amount of carbon atoms from at least C2 to C30 in the substituent and / or salts thereof. Additionally or alternatively, the at least one nucleating agent is treated with at least one surfacetreatment agent, which is at least one mono-substituted succinic anhydride consisting of succinic anhydride mono-substituted with a group being a branched aliphatic group having a total amount of carbon atoms from at least C3 to C30 in the substituent and / or salts thereof. Additionally or alternatively, the at least one nucleating agent is treated with at least one surface-treatment agent, which is at least one mono-substituted succinic anhydride consisting of succinic anhydride monosubstituted with a group being a cyclic aliphatic group having a total amount of carbon atoms from at least C5 to C30 in the substituent and / or salts thereof.

[0123] Accordingly, it should be noted that the at least one mono-substituted succinic anhydride may be one kind of mono-substituted succinic anhydride. Alternatively, the at least one mono-substituted succinic anhydride may be a mixture of two or more kinds of mono-substituted succinic anhydride. For example, the at least one mono-substituted succinic anhydride may be a mixture of two or three kinds of mono-substituted succinic anhydride, like two kinds of mono-substituted succinic anhydride.

[0124] In one embodiment of the present invention, the at least one mono-substituted succinic anhydride is one kind of mono-substituted succinic anhydride.

[0125] It is appreciated that the at least one mono-substituted succinic anhydride represents a surface treatment agent and consists of succinic anhydride mono-substituted with a group selected from any linear, branched, aliphatic, and cyclic group having a total amount of carbon atoms from C2 to C30 in the substituent.

[0126] In one embodiment of the present invention, the at least one mono-substituted succinic anhydride consists of succinic anhydride mono-substituted with a group selected from a linear, branched, aliphatic, and cyclic group having a total amount of carbon atoms from C3 to C20 in the substituent. For example, the at least one mono-substituted succinic anhydride consists of succinic anhydride mono-substituted with a group selected from a linear, branched, aliphatic, and cyclic group having a total amount of carbon atoms from C4 to C18 in the substituent. Preferably, the surfacetreatment composition comprises a further surface-treatment agent, which is at least one monosubstituted succinic anhydride consisting of succinic anhydride mono-substituted with a group being a linear aliphatic group having a total amount of carbon atoms from C3 to C20, more preferably from C4 to C18, in the substituent and / or salts thereof. Additionally or alternatively, the surface-treatment composition comprises a further surface-treatment agent, which is at least one mono-substituted succinic anhydride consisting of succinic anhydride mono-substituted with a group being a branched aliphatic group having a total amount of carbon atoms from C3 to C20, more preferably from C4 to C18, in the substituent and / or salts thereof. Additionally or alternatively, the surface-treatment composition comprises a further surface-treatment agent, which is at least one mono-substituted succinic anhydride consisting of succinic anhydride mono-substituted with a group being a cyclic aliphatic group having a total amount of carbon atoms from C5 to C20, more preferably from C5 to C18 in the substituent and / or salts thereof.

[0127] In one embodiment of the present invention, the at least one mono-substituted succinic anhydride consists of succinic anhydride mono-substituted with one group being a linear and aliphatic group having a total amount of carbon atoms from C2 to C30, preferably from C3 to C20 and most preferably from C4 to C18 in the substituent. Additionally or alternatively, the at least one monosubstituted succinic anhydride consists of succinic anhydride mono-substituted with one group being a branched and aliphatic group having a total amount of carbon atoms from C3 to C30, preferably from C3 to C20 and most preferably from C4 to C18 in the substituent.

[0128] Thus, it is preferred that the at least one mono-substituted succinic anhydride consists of succinic anhydride mono-substituted with one group being a linear alkyl group having a total amount of carbon atoms from C2 to C30, preferably from C3 to C20 and most preferably from C4 to C18 in the substituent. Additionally or alternatively, it is preferred that the at least one mono-substituted succinic anhydride consists of succinic anhydride mono-substituted with one group being a branched alkyl group having a total amount of carbon atoms from C3 to C30, preferably from C3 to C20 and most preferably from C4 to C18 in the substituent. For example, the at least one mono-substituted succinic anhydride consists of succinic anhydride mono-substituted with one group being a linear alkyl group having a total amount of carbon atoms from C2 to C30, preferably from C3 to C20 and most preferably from C4 to C18 in the substituent. Additionally or alternatively, the at least one mono-substituted succinic anhydride consists of succinic anhydride mono-substituted with one group being a branched alkyl group having a total amount of carbon atoms from C3 to C30, preferably from C3 to C20 and most preferably from C4 to C18 in the substituent.

[0129] In one embodiment of the present invention, the at least one mono-substituted succinic anhydride is at least one linear or branched alkyl mono-substituted succinic anhydride. For example, the at least one alkyl mono-substituted succinic anhydride is selected from the group comprising ethylsuccinic anhydride, propylsuccinic anhydride, butylsuccinic anhydride, triisobutyl succinic anhydride, pentylsuccinic anhydride, hexylsuccinic anhydride, heptylsuccinic anhydride, octylsuccinic anhydride, nonylsuccinic anhydride, decyl succinic anhydride, dodecyl succinic anhydride, hexadecanyl succinic anhydride, octadecanyl succinic anhydride, and mixtures thereof.

[0130] Accordingly, it is appreciated that, e.g., the term “butylsuccinic anhydride” comprises linear and branched butylsuccinic anhydride(s). One specific example of linear butylsuccinic anhydride(s) is n-butylsuccinic anhydride. Specific examples of branched butylsuccinic anhydride(s) are isobutylsuccinic anhydride, sec-butylsuccinic anhydride and / or tert-butylsuccinic anhydride.

[0131] Furthermore, it is appreciated that, e.g., the term “hexadecanyl succinic anhydride” comprises linear and branched hexadecanyl succinic anhydride(s). One specific example of linear hexadecanyl succinic anhydride(s) is n-hexadecanyl succinic anhydride. Specific examples of branched hexadecanyl succinic anhydride(s) are 14-methylpentadecanyl succinic anhydride, 13- methylpentadecanyl succinic anhydride, 12-methylpentadecanyl succinic anhydride, 11- methylpentadecanyl succinic anhydride, 10-methylpentadecanyl succinic anhydride, 9-methylpentadecanyl succinic anhydride, 8-methylpentadecanyl succinic anhydride, 7- methylpentadecanyl succinic anhydride, 6-methylpentadecanyl succinic anhydride, 5- methylpentadecanyl succinic anhydride, 4-methylpentadecanyl succinic anhydride, 3- methylpentadecanyl succinic anhydride, 2-methylpentadecanyl succinic anhydride, 1- methylpentadecanyl succinic anhydride, 13-ethylbutadecanyl succinic anhydride, 12-ethylbutadecanyl succinic anhydride, 11-ethylbutadecanyl succinic anhydride, 10-ethylbutadecanyl succinic anhydride, 9-ethylbutadecanyl succinic anhydride, 8-ethylbutadecanyl succinic anhydride, 7-ethylbutadecanyl succinic anhydride, 6-ethylbutadecanyl succinic anhydride, 5-ethylbutadecanyl succinic anhydride, 4-ethylbutadecanyl succinic anhydride, 3-ethylbutadecanyl succinic anhydride, 2-ethylbutadecanyl succinic anhydride, 1-ethylbutadecanyl succinic anhydride, 2-butyldodecanyl succinic anhydride, 1- hexyldecanyl succinic anhydride, 1-hexyl-2-decanyl succinic anhydride, 2-hexyldecanyl succinic anhydride, 6,12-dimethylbutadecanyl succinic anhydride, 2,2-diethyldodecanyl succinic anhydride, 4,8,12-trimethyltridecanyl succinic anhydride, 2,2,4,6,8-pentamethylundecanyl succinic anhydride, 2- ethyl-4-methyl-2-(2-methylpentyl)-heptyl succinic anhydride and / or 2-ethyl-4,6-dimethyl-2-propylnonyl succinic anhydride.

[0132] Furthermore, it is appreciated that e.g. the term “octadecanyl succinic anhydride” comprises linear and branched octadecanyl succinic anhydride(s). One specific example of linear octadecanyl succinic anhydride(s) is n-octadecanyl succinic anhydride. Specific examples of branched hexadecanyl succinic anhydride(s) are 16-methylheptadecanyl succinic anhydride, 15- methylheptadecanyl succinic anhydride, 14-methylheptadecanyl succinic anhydride, 13- methylheptadecanyl succinic anhydride, 12-methylheptadecanyl succinic anhydride, 11-methylheptadecanyl succinic anhydride, 10-methylheptadecanyl succinic anhydride, 9- methylheptadecanyl succinic anhydride, 8-methylheptadecanyl succinic anhydride, 7- methylheptadecanyl succinic anhydride, 6-methylheptadecanyl succinic anhydride, 5- methylheptadecanyl succinic anhydride, 4-methylheptadecanyl succinic anhydride, 3- methylheptadecanyl succinic anhydride, 2-methylheptadecanyl succinic anhydride, 1- methylheptadecanyl succinic anhydride, 14-ethylhexadecanyl succinic anhydride, 13- ethylhexadecanyl succinic anhydride, 12-ethylhexadecanyl succinic anhydride, 11-ethylhexadecanyl succinic anhydride, 10-ethylhexadecanyl succinic anhydride, 9-ethylhexadecanyl succinic anhydride, 8-ethylhexadecanyl succinic anhydride, 7-ethylhexadecanyl succinic anhydride, 6-ethylhexadecanyl succinic anhydride, 5-ethylhexadecanyl succinic anhydride, 4-ethylhexadecanyl succinic anhydride, 3-ethylhexadecanyl succinic anhydride, 2-ethylhexadecanyl succinic anhydride, 1-ethylhexadecanyl succinic anhydride, 2-hexyldodecanyl succinic anhydride, 2-heptylundecanyl succinic anhydride, iso- octadecanyl succinic anhydride and / or 1-octyl-2-decanyl succinic anhydride.

[0133] In one embodiment of the present invention, the at least one alkyl mono-substituted succinic anhydride is selected from the group comprising butylsuccinic anhydride, hexylsuccinic anhydride, heptylsuccinic anhydride, octylsuccinic anhydride, hexadecanyl succinic anhydride, octadecanyl succinic anhydride, and mixtures thereof.

[0134] In one embodiment of the present invention, the at least one mono-substituted succinic anhydride is one kind of alkyl mono-substituted succinic anhydride. For example, the one alkyl monosubstituted succinic anhydride is butylsuccinic anhydride. Alternatively, the one alkyl mono-substituted succinic anhydride is hexylsuccinic anhydride. Alternatively, the one alkyl mono-substituted succinic anhydride is heptylsuccinic anhydride or octylsuccinic anhydride. Alternatively, the one alkyl monosubstituted succinic anhydride is hexadecanyl succinic anhydride. For example, the one alkyl monosubstituted succinic anhydride is linear hexadecanyl succinic anhydride such as n-hexadecanyl succinic anhydride or branched hexadecanyl succinic anhydride such as 1-hexyl-2-decanyl succinic anhydride. Alternatively, the one alkyl mono-substituted succinic anhydride is octadecanyl succinic anhydride. For example, the one alkyl mono-substituted succinic anhydride is linear octadecanyl succinic anhydride such as n-octadecanyl succinic anhydride or branched octadecanyl succinic anhydride such as iso-octadecanyl succinic anhydride or 1-octyl-2-decanyl succinic anhydride.

[0135] In one embodiment of the present invention, the one alkyl mono-substituted succinic anhydride is butylsuccinic anhydride such as n-butylsuccinic anhydride.

[0136] In one embodiment of the present invention, the at least one mono-substituted succinic anhydride is a mixture of two or more kinds of alkyl mono-substituted succinic anhydrides. For example, the at least one mono-substituted succinic anhydride is a mixture of two or three kinds of alkyl mono-substituted succinic anhydrides.

[0137] According to another embodiment of the present invention, the at least one nucleating agent is treated with at least one surface-treatment agent, which is at least one polydialkylsiloxane. Preferred polydialkylsiloxanes are described e.g. in US 2004 / 0097616 A1. Most preferred are polydialkylsiloxanes selected from the group consisting of polydimethylsiloxane, preferably dimethicone, polydiethylsiloxane and polymethylphenylsiloxane and / or mixtures thereof.

[0138] For example, the at least one polydialkylsiloxane is preferably a polydimethylsiloxane (PDMS).

[0139] In one embodiment, the at least one nucleating agent is treated with at least one surfacetreatment agent, preferably one surface-treatment agent, selected from the group consisting of

[0140] I) a phosphoric acid ester blend of one or more phosphoric acid mono ester and / or salts thereof and / or one or more phosphoric acid di-ester and / or salts thereof, and / or

[0141] II) at least one saturated or unsaturated aliphatic linear or branched carboxylic acid and / or salts thereof, preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C4 to C24 and / or a salt thereof, more preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C12 to C20 and / or a salt thereof, most preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C16 to C18 and / or salts thereof, and / or

[0142] III) at least one mono-substituted succinic anhydride consisting of succinic anhydride mono-substituted with a group selected from a linear, branched, aliphatic and cyclic group having a total amount of carbon atoms from at least C2 to C30 in the substituent and / or salts thereof, and / or

[0143] V) mixtures of one or more materials according to I) to III).

[0144] For example, the at least one nucleating agent is treated with one surface-treatment agent selected from the group consisting of

[0145] I) a phosphoric acid ester blend of one or more phosphoric acid mono ester and / or salts thereof and / or one or more phosphoric acid di-ester and / or salts thereof, or

[0146] II) at least one saturated or unsaturated aliphatic linear or branched carboxylic acid and / or salts thereof, preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C4 to C24 and / or a salt thereof, more preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C12 to C20 and / or a salt thereof, most preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C16 to C18 and / or salts thereof, or

[0147] III) at least one mono-substituted succinic anhydride consisting of succinic anhydride mono-substituted with a group selected from a linear, branched, aliphatic and cyclic group having a total amount of carbon atoms from at least C2 to C30 in the substituent and / or salts thereof.

[0148] Preferably, the at least one nucleating agent is treated with one surface-treatment agent selected from the group consisting of

[0149] I) a phosphoric acid ester blend of one or more phosphoric acid mono ester and / or salts thereof and / or one or more phosphoric acid di-ester or a salt thereof, or

[0150] II) a saturated or unsaturated aliphatic linear or branched carboxylic acid and / or a salt thereof, preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C4 to C24 and / or a salt thereof, more preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C12 to C20 and / or a salt thereof, most preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C16 to C18 or a salt thereof, or III) a mono-substituted succinic anhydride consisting of succinic anhydride monosubstituted with a group selected from a linear, branched, aliphatic and cyclic group having a total amount of carbon atoms from at least C2 to C30 in the substituent or a salt thereof.

[0151] In another embodiment, the at least one nucleating agent is treated with at least one surfacetreatment agent, preferably one surface-treatment agent, selected from the group consisting of

[0152] II) at least one saturated or unsaturated aliphatic linear or branched carboxylic acid and / or salts thereof, preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C4 to C24 and / or a salt thereof, more preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C12 to C20 and / or a salt thereof, most preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C16 to C18 and / or a salt thereof and / or

[0153] III) at least one mono-substituted succinic anhydride consisting of succinic anhydride mono-substituted with a group selected from a linear, branched, aliphatic and cyclic group having a total amount of carbon atoms from at least C2 to C30 in the substituent and / or salts thereof.

[0154] For example, the at least one nucleating agent is treated with one surface-treatment agent selected from the group consisting of

[0155] II) at least one saturated or unsaturated aliphatic linear or branched carboxylic acid and / or salts thereof, preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C4 to C24 and / or a salt thereof, more preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C12 to C20 and / or a salt thereof, most preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C16 to C18 and / or salts thereof, or

[0156] III) at least one mono-substituted succinic anhydride consisting of succinic anhydride mono-substituted with a group selected from a linear, branched, aliphatic and cyclic group having a total amount of carbon atoms from at least C2 to C30 in the substituent and / or salts thereof.

[0157] Preferably, the at least one nucleating agent is treated with one surface-treatment agent selected from the group consisting of

[0158] II) a saturated or unsaturated aliphatic linear or branched carboxylic acid and / or salts thereof, preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C4 to C24 and / or a salt thereof, more preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C12 to C20 and / or a salt thereof, most preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C16 to C18 or a salt thereof, or

[0159] III) a mono-substituted succinic anhydride consisting of succinic anhydride monosubstituted with a group selected from a linear, branched, aliphatic and cyclic group having a total amount of carbon atoms from at least C2 to C30 in the substituent or a salt thereof.

[0160] In a preferred embodiment, the at least one nucleating agent is surface-treated with at least one saturated or unsaturated aliphatic linear or branched carboxylic acid and / or salts thereof, preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C4 to C24 and / or a salt thereof, more preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C12 to C20 and / or a salt thereof, most preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C16 to C18 and / or a salt thereof. Alternatively, the at least one nucleating agent is surface-treated with at least one mono-substituted succinic anhydride consisting of succinic anhydride mono-substituted with a group selected from a linear, branched, aliphatic and cyclic group having a total amount of carbon atoms from at least C2 to C30 in the substituent and / or salts thereof. Preferably, the at least one nucleating agent is surface-treated with at least one saturated or unsaturated aliphatic linear or branched carboxylic acid and / or salts thereof, preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C4 to C24 and / or a salt thereof, more preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C12 to C20 and / or a salt thereof, most preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C16 to C18 and / or a salt thereof.

[0161] For example, the at least one nucleating agent is surface-treated with one saturated or unsaturated aliphatic linear or branched carboxylic acid or a salt thereof, preferably one aliphatic carboxylic acid having a total amount of carbon atoms from C4 to C24 or a salt thereof, more preferably aliphatic carboxylic acid having a total amount of carbon atoms from C12 to C20 or a salt thereof, most preferably one aliphatic carboxylic acid having a total amount of carbon atoms from C16 to C18 or a salt thereof.

[0162] Most preferably, the at least one nucleating agent is surface-treated with stearic acid.

[0163] The surface-treated nucleating agent of the present invention is preferably formed in that the at least one nucleating agent is contacted with the at least one surface-treatment agent such that a treatment layer comprising the at least one surface-treatment agent and / or salty reaction products thereof is formed on the surface of the at least one nucleating agent.

[0164] The at least one nucleating agent is contacted with the surface-treatment agent preferably in an amount from 0.3 to 10 mg / m2of the at least one nucleating agent surface, preferably 0.5 to 8 mg / m2, more preferably 0.8 to 3 mg / m2. For example, at least one nucleating agent is contacted with the surface-treatment agent preferably in an amount from 0.8 to 2.8 mg / m2or from 0.8 to 2.6 mg / m2of the at least one nucleating agent surface.

[0165] Preferably, the at least one surface-treatment agent is present on the at least one nucleating agent in an amount ranging from 0.2 to 4.5 wt.-%, more preferably from 0.3 to 3 wt.-% and most preferably from 0.5 to 1 .5 wt.-%, based on the total weight of the at least one nucleating agent. That is, a chemical reaction may take place between the at least one nucleating agent and the surface treatment agent. In other words, the treatment layer may comprise the surface treatment agent and / or salty reaction products thereof.

[0166] The term "salty reaction products" of the further surface-treatment agent refers to products obtained by contacting the at least one nucleating agent with the surface-treatment agent. Said reaction products are formed between at least a part of the applied surface-treatment agent and reactive molecules located at the surface of the at least one nucleating agent.

[0167] Thus, the at least one nucleating agent of the present invention is preferably a surface-treated (e.g. stearic acid treated) nucleating agent.

[0168] It is required that the polystyrene polymer formulation comprises the at least one nucleating agent, e.g. the untreated or (stearic acid) surface treated nucleating agent, in an amount ranging from > 3 to 15 wt.-%, based on the total weight of the formulation. For example, the polystyrene polymer formulation comprises the at least one nucleating agent, e.g. the untreated or (stearic acid) surface treated nucleating agent, in an amount ranging from 3.8 to 15 wt.-%, preferably from 4 to 15 wt.-%, more preferably from 4.5 to 15 wt.-%, even more preferably from 5 to 15 wt.-% and most preferably from 5.5 to 15 wt.-%, based on the total weight of the formulation.

[0169] In one embodiment, the polystyrene polymer formulation comprises the at least one nucleating agent, e.g. the untreated or (stearic acid) surface treated nucleating agent, in an amount ranging from

[0170] > 3 to 10 wt.-%, preferably from 3.8 to 10 wt.-% and most preferably from 4 to 10 wt.-%, based on the total weight of the formulation.

[0171] Preferably, the polystyrene polymer formulation comprises the at least one nucleating agent, e.g. the untreated or (stearic acid) surface treated nucleating agent, in an amount ranging from > 3 to 10 wt.-%, more preferably from 4 to 10 wt.-%, based on the total weight of the formulation.

[0172] In one embodiment, the polystyrene polymer formulation comprises the at least one nucleating agent, e.g. the untreated or (stearic acid) surface treated nucleating agent, in an amount ranging from

[0173] > 3.8 to 15 wt.-%, more preferably from > 4 to 15 wt.-%, even more preferably from > 4.5 to 15 wt.-%, still more preferably from > 5 to 15 wt.-% and most preferably from > 5.5 to 15 wt.-%, based on the total weight of the formulation. For example, the polystyrene polymer formulation comprises the at least one nucleating agent, e.g. the untreated or (stearic acid) surface treated nucleating agent, in an amount ranging from 3.8 to 10 wt.-%, e.g. from > 3.8 to 10 wt.-%, more preferably from 4 to 10 wt.-%, e.g. from > 4 to 10 wt.-%, even more preferably from 4.5 to 10 wt.-%, e.g. from > 4.5 to 10 wt.-%, still more preferably from 5 to 10 wt.-%, e.g. from > 5 to 10 wt.-%, and most preferably from 5.5 to 10 wt.- %, e.g. from > 5.5 to 10 wt.-%, based on the total weight of the formulation.

[0174] In one embodiment, the polystyrene polymer formulation comprises the at least one nucleating agent, e.g. the untreated or (stearic acid) surface treated nucleating agent, in an amount ranging from

[0175] > 5 to 15 wt.-%, more preferably from > 5 to 10 wt.-%, preferably from 5.5 to 10 wt.-%, based on the total weight of the formulation.

[0176] It is appreciated that the polystyrene polymer formulation may comprise typical additives that are used in the field of polystyrene foams. For example, the polymer formulation further comprises one or more additives selected from the group comprising crosslinking agents, colouring pigments, filler, fibers, dyes, waxes, lubricants, oxidative- and / or UV-stabilizers, adhesion promoter, antioxidants, process stabilizers, flame retardants, processing aids and mixtures thereof. In one embodiment, the polymer formulation further comprises one or more additives selected from the group consisting of crosslinking agents, colouring pigments, filler, fibers, dyes, waxes, lubricants, oxidative- and / or UV- stabilizers, adhesion promoter, antioxidants, process stabilizers, flame retardants, anti-dripping agents, blowing agents, processing aids and mixtures thereof.

[0177] In a preferred embodiment, the polystyrene polymer formulation comprises one or more blowing agents. Such blowing agents are well known in the art. For example, pentane, carbon dioxide and / or ethanol, preferably carbon dioxide and ethanol, are used as blowing agent(s). If carbon dioxide and ethanol are used as blowing agent, their weight ratio [carbon dioxide:ethanol] is preferably from 90:10 to 10:90, more preferably from 70:30 to 30:70, e.g. about 60 / 40. In one embodiment, the polystyrene polymer formulation thus comprises, preferably consists of, a polystyrene comprising polymer material, from > 3 to 15 wt.-%, based on the total weight of the formulation, of at least one nucleating agent selected from the group consisting of a particulate earth alkali carbonate-comprising material, a particulate earth alkali phosphate-comprising material, a particulate hydroxide-comprising material and mixtures thereof, and one or more additives selected from the group comprising, e.g. consisting of, crosslinking agents, colouring pigments, filler, fibers, dyes, waxes, lubricants, oxidative- and / or UV-stabilizers, adhesion promoter, antioxidants, process stabilizers, flame retardants, anti-dripping agents, blowing agents, processing aids and mixtures thereof.

[0178] It is preferred that the polystyrene polymer formulation comprises a processing aid. In a preferred embodiment, the polystyrene polymer formulation thus comprises, preferably consists of, a polystyrene comprising polymer material, from > 3 to 15 wt.-%, based on the total weight of the formulation, of a nucleating agent selected from the group consisting of a particulate earth alkali carbonate-comprising material, a particulate earth alkali phosphate-comprising material, a particulate hydroxide-comprising material and mixtures thereof, and a processing aid as additive and one or more additives selected from the group comprising, e.g. consisting of, crosslinking agents, colouring pigments, filler, fibers, dyes, waxes, lubricants, oxidative- and / or UV-stabilizers, adhesion promoter, antioxidants, process stabilizers, flame retardants anti-dripping agents, blowing agents and mixtures thereof.

[0179] It is appreciated that acrylic co-polymer(s), e.g. with high molecular weight, can be used as processing aid(s). Such processing aid(s) may contribute to the melt strength of the polystyrene polymer formulation and thus may stabilize the foam bubbles before "freezing" of the cell structure by cooling down. Thus, the polystyrene polymer formulation preferably comprises such processing aid(s) in an amount ranging from 0.1 to 7 wt.-%, preferably from 0.5 to 5 wt.-%, based on the total weight of the polystyrene polymer formulation.

[0180] In one embodiment, the polystyrene polymer formulation preferably comprises the one or more additives in an amount ranging from 0.1 to 25 wt.-%, based on the total weight of the polystyrene polymer formulation, preferably from 0.5 to 23 wt.-%, more preferably from 1 to 20 wt.-% and most preferably from 1 .2 to 18 wt.-%. It is appreciated that the amount of the one or more additives refers to the total amount of the one or more additives.

[0181] If the polystyrene polymer formulation comprises one or more blowing agents as additive(s), the total amount of the blowing agents depends on the target foam density and may go up to several wt.-%, based on the total weight of the polystyrene comprising polymer material.

[0182] In a preferred embodiment, the polystyrene polymer formulation comprises, preferably consists of, a polystyrene comprising polymer material, from > 3 to 15 wt.-%, based on the total weight of the formulation, of at least one nucleating agent selected from the group consisting of a particulate earth alkali carbonate-comprising material, a particulate earth alkali phosphate-comprising material, a particulate hydroxide-comprising material and mixtures thereof, and from 0.1 to 25 wt.-%, based on the total weight of the polystyrene polymer formulation, of one or more additives selected from the group comprising, e.g. consisting of, crosslinking agents, colouring pigments, filler, fibers, dyes, waxes, lubricants, oxidative- and / or UV-stabilizers, adhesion promoter, antioxidants, process stabilizers, flame retardants, anti-dripping agents, blowing agents, processing aids and mixtures thereof.

[0183] For example, the polystyrene polymer formulation comprises, preferably consists of, a polystyrene comprising polymer material, from > 3 to 15 wt.-%, based on the total weight of the formulation, of at least one nucleating agent selected from the group consisting of a particulate earth alkali carbonate-comprising material, a particulate earth alkali phosphate-comprising material, a particulate hydroxide-comprising material and mixtures thereof, and from 0.1 to 7 wt.-%, based on the total weight of the polystyrene polymer formulation of a processing aid as additive.

[0184] In another embodiment, the polystyrene polymer formulation comprises, preferably consists of, a polystyrene comprising polymer material, from > 3 to 15 wt.-%, based on the total weight of the formulation, of at least one nucleating agent selected from the group consisting of a particulate earth alkali carbonate-comprising material, a particulate earth alkali phosphate-comprising material, a particulate hydroxide-comprising material and mixtures thereof, and from 0.1 to 7 wt.-%, based on the total weight of the polystyrene polymer formulation of a processing aid as additive and one or more additives selected from the group comprising, e.g. consisting of, crosslinking agents, colouring pigments, filler, fibers, dyes, waxes, lubricants, oxidative- and / or UV-stabilizers, adhesion promoter, antioxidants, process stabilizers, flame retardants anti-dripping agents, blowing agents and mixtures thereof such that the total amount of additives ranges from 0.1 to 25 wt.-%, based on the total weight of the polystyrene polymer formulation.

[0185] In an alternative embodiment, the polystyrene polymer formulation comprises, preferably consists of, a polystyrene comprising polymer material, from > 3 to 15 wt.-%, based on the total weight of the formulation, of at least one nucleating agent selected from the group consisting of a particulate earth alkali carbonate-comprising material, a particulate earth alkali phosphate-comprising material, a particulate hydroxide-comprising material and mixtures thereof, and from 0.5 to 1 .5 wt.-%, based on the total weight of the polystyrene comprising polymer material, of one or more blowing agents and optionally stabilizer(s).

[0186] The polystyrene polymer formulation is preferably used for the preparation of polystyrene foam. Thus, the polystyrene polymer formulation is preferably a foam formulation.

[0187] The polystyrene polymer formulation is preferably present in the form of pellets. Such pellets preferably have particle sizes of from 1 to 6 mm, more preferably from 2 to 5 mm. The particle size refers to the longest dimension and is preferably controlled (selected) by sieving the pellets through a screen of defined size. The skilled person is well aware of such methods.

[0188] Alternatively, the polystyrene foam may be obtained by directly adding the at least one nucleating agent and optional one or more blowing agent into the polystyrene comprising polymer material in a foam extrusion process. In this embodiment, the polystyrene polymer formulation is thus formed in an extruder, e.g. in a twin-screw extruder, directly during the foaming process.

[0189] Process for preparing the polystyrene polymer formulation

[0190] According to one aspect of the present invention, the polystyrene polymer formulation of the present invention is prepared by a process comprising the following steps: a) providing a polystyrene comprising polymer material, b) providing from > 3 to 15 wt.-%, based on the total weight of the formulation, of at least one nucleating agent selected from the group consisting of a particulate earth alkali carbonate- comprising material, a particulate earth alkali phosphate-comprising material and mixtures thereof, and c) contacting the components of step a) and step b) and optional additives in any order such that a polystyrene polymer formulation is formed.

[0191] In one embodiment, the process comprises a further step b1) of providing one or more additives selected from the group comprising crosslinking agents, colouring pigments, filler, fibers, dyes, waxes, lubricants, oxidative- and / or UV-stabilizers, adhesion promoter, antioxidants, process stabilizers, flame retardants, anti-dripping agents, blowing agents, processing aids and mixtures thereof.

[0192] In this case, the process for preparing the polystyrene polymer formulation comprises the steps of: a) providing a polystyrene comprising polymer material, b) providing from > 3 to 15 wt.-%, based on the total weight of the formulation, of at least one nucleating agent selected from the group consisting of a particulate earth alkali carbonate- comprising material, a particulate earth alkali phosphate-comprising material and mixtures thereof, b1) providing one or more additives selected from the group comprising crosslinking agents, colouring pigments, filler, fibers, dyes, waxes, lubricants, oxidative- and / or UV-stabilizers, adhesion promoter, antioxidants, process stabilizers, flame retardants, anti-dripping agents, blowing agents, processing aids and mixtures thereof, and c) contacting the components of step a), step b) and step b1) in any order such that a polystyrene polymer formulation is formed.

[0193] As regards the polystyrene comprising polymer material, the at least one nucleating agent and preferred embodiments thereof, reference is made to the comments provided above when discussing the polystyrene polymer formulation in detail.

[0194] It is appreciated that the polystyrene comprising polymer material in step a) is preferably provided in dry form. Additionally or alternatively, the at least one nucleating agent in step b) is preferably provided in dry form. Additionally or alternatively, the one or more additive(s) in step b1), if present, is / are preferably provided in dry form.

[0195] In a preferred embodiment, the polystyrene comprising polymer material in step a) is provided in dry form, the at least one nucleating agent in step b) is provided in dry form, and the one or more additive(s) in step b1), if present, is / are provided in dry form.

[0196] In a preferred embodiment, the polystyrene polymer formulation is thus prepared in a dry process. With respect to the process, it is to be noted that the wording “dry form” or “dry process” means that the compounds of step a), step b) and optional step b1) are provided without the use of solvent(s) such as water.

[0197] It is appreciated that the polystyrene comprising polymer material of step a) may be in solid, highly viscous or liquid state. Typically, the polystyrene comprising polymer material of step a) is in highly viscous or liquid state. It is preferred that the polystyrene comprising polymer material of step a) is provided in liquid state in process step c). Thus, the polystyrene comprising polymer material of step a) is optionally heated to provide the polystyrene comprising polymer material in liquid or molten stated, i.e. in a less viscous state. In one embodiment, contacting step c) of the process thus includes a heating of the polystyrene comprising polymer material of step a). Such a heating is preferably carried out in case the polystyrene comprising polymer material of step a) is solid or highly viscous. However, even if the polystyrene comprising polymer material of step a) is in liquid state it may be favourable to carry out a heating in step e) in order to speed up and increase the reaction.

[0198] In general, step c) is preferably carried out at a temperature from 180 to 280°C, preferably from 180 to 230°C, and most preferably from 190 to 220°C, e.g. at 210°C. It is appreciated that the temperature in step c) is adjusted such that the polystyrene comprising polymer material is in a liquid or molten state but without thermally decomposing the polystyrene comprising polymer material.

[0199] In one embodiment, the polystyrene comprising polymer material of step a) is preferably added in dry form and heated (i.e. the polystyrene comprising polymer material is made less viscous) once in contact with the at least one nucleating agent of step b). It is also possible that at least one nucleating agent is contacted under mixing, in one or more steps, with the polystyrene comprising polymer material and subsequently heated.

[0200] Step c) is preferably carried out under mixing. It is appreciated that the mixing can be carried out by any method known to the skilled person resulting in a homogeneous composition. For example, step c) is carried out in a twin screw extruder with one or more side feeders.

[0201] It is appreciated that step c) can be carried out in that the components of step a), step b), and optional step b1) are contacted in any order.

[0202] In a preferred embodiment, contacting step c) is carried out in that firstly the at least one nucleating agent of step b) is contacted under mixing, in one or more steps, with the polystyrene comprising polymer material of step a).

[0203] If one or more additive(s) is / are added, contacting step c) is preferably carried out in that firstly the at least one nucleating agent of step b) is contacted under mixing, in one or more steps, with the one or more additive(s) of step b1) and the mixture obtained is contacted under mixing, in one or more steps, with the polystyrene comprising polymer material of step a).

[0204] The term “one step” means that the respective compound is completely added into the contacting step c). Contrary thereto, “(two or) more steps” are carried out if the respective compound is added in several portions into contacting step c).

[0205] In this embodiment, the present process comprises the following steps: a) providing a polystyrene comprising polymer material, b) providing from > 3 to 15 wt.-%, based on the total weight of the formulation, of at least one nucleating agent selected from the group consisting of a particulate earth alkali carbonate- comprising material, a particulate earth alkali phosphate-comprising material and mixtures thereof, and c) contacting the components of step a) and step b) in any order such that a polystyrene polymer formulation is formed, wherein the at least one nucleating agent of step b) is contacted under mixing, in one or more steps, with the polystyrene comprising polymer material.

[0206] If one or more additive(s) is / are added, the present process preferably comprises the following steps: a) providing a polystyrene comprising polymer material, b) providing from > 3 to 15 wt.-%, based on the total weight of the formulation, of at least one nucleating agent selected from the group consisting of a particulate earth alkali carbonate- comprising material, a particulate earth alkali phosphate-comprising material and mixtures thereof, b1) providing one or more additives selected from the group comprising crosslinking agents, colouring pigments, filler, fibers, dyes, waxes, lubricants, oxidative- and / or UV-stabilizers, adhesion promoter, antioxidants, process stabilizers, flame retardants, anti-dripping agents, blowing agents, processing aids and mixtures thereof, and c) contacting the components of step a), step b) and step b1) in any order such that a polystyrene polymer formulation is formed, wherein firstly the at least one nucleating agent of step b) is contacted under mixing, in one or more steps, with the one or more additive(s) of step b1) and the mixture obtained is contacted under mixing, in one or more steps, with the polystyrene comprising polymer material of step a).

[0207] It is appreciated that contacting step c) is preferably an extrusion step resulting in pellets. Such extrusion processes, e.g. in a twin screw extruder, for obtaining pellets of a polymer formulation are well known in the art. Alternatively, contacting step c) is a direct foam extrusion process, or a process for preparing so-called micro-granules for the expanded polystyrene (EPS) foam process, where no further extrusion process is available in which the blowing agent can be implemented into the polymer material later on. Thus, the polystyrene polymer formulation is thus formed in an extruder, e.g. in a twin-screw extruder, during the foaming process, or during the preparation of the microgranules for the EPS process. The micro-granules preferably have particle sizes of from 0.1 to 3 mm, more preferably from 0.1 to 2 mm. The micro-granules are preferably round shaped (spherical), and their particle size refers to the longest dimension and is preferably controlled (selected) by sieving the micro-granules through a screen of defined size. The skilled person is well aware of such methods. In this embodiment, the present process preferably comprises the following steps: a) providing a polystyrene comprising polymer material, b) providing from > 3 to 15 wt.-%, based on the total weight of the formulation, of at least one nucleating agent selected from the group consisting of a particulate earth alkali carbonate- comprising material, a particulate earth alkali phosphate-comprising material and mixtures thereof, b1) providing one or more blowing agents and optionally stabilizer(s), and c) contacting the components of step a), step b) and step b1) in any order such that a polystyrene polymer formulation is formed, preferably the polystyrene comprising polymer material of step a) is contacted under mixing, in one or more steps, with the at least one nucleating agent of step b) and the one or more blowing agents and optional stabilizer(s) of step b1).

[0208] It is appreciated that the pellets are then preferably further processed, e.g. by foaming, to generate foams and articles of the inventive formulation.

[0209] Polystyrene foam, process and use

[0210] Another aspect of the present invention refers to a polystyrene foam comprising a polystyrene comprising polymer material and from > 3 to 15 wt.-%, based on the total weight of the formulation, of at least one nucleating agent selected from the group consisting of a particulate earth alkali carbonate- comprising material, a particulate earth alkali phosphate-comprising material and mixtures thereof. It is appreciated that that the polystyrene foam is obtained by foaming the polystyrene polymer formulation. Preferably, the polystyrene foam is a XPS foam or an EPS foam. For example, the polystyrene foam is a XPS foam.

[0211] The polystyrene foam can be prepared by any method known to the skilled person. A suitable process for preparing the polystyrene foam comprises the steps of i) providing the polystyrene polymer formulation defined herein, and ii) foaming the formulation of step i) such that a foam is formed.

[0212] As regards the polystyrene polymer formulation and preferred embodiments thereof, reference is made to the comments provided above when discussing the polystyrene polymer formulation in detail.

[0213] The foaming in step ii) may be performed by any method known to the skilled person resulting in a foaming of the polystyrene polymer formulation.

[0214] However, it is appreciated that the polystyrene foam is preferably a XPS (extruded polystyrene) foam. Thus, the XPS foam is preferably obtained via an extrusion process where the polystyrene polymer formulation is extruded through a die. Often a so-called tandem extrusion line is used, where the primary extruder is a single or twin-screw extruder with injection units for the blowing agent(s), and the secondary extruder is used for a highly efficient cooling down of the polymer melt before leaving the extruder via the die into a calibration unit. The extruded foam then cools and expands into its final shape.

[0215] Alternatively, it is appreciated that the polystyrene foam is preferably an EPS (expanded polystyrene) foam. Thus, the EPS foam is preferably produced from micro-granules prepared by extrusion of the polystyrene polymer formulation, pre-expansion of them typically by hot water steam and finally processing the expanded beads into a mold again typically by support of hot water steam. Heat or hot water steam finally expands the pre-expanded polystyrene polymer formulation beads and fuses them together. The expansion process under heat causes the expanded foam to fuse together. The fusion results in an irregular pattern that leaves irregular gaps in-between the originally preexpanded foam beads. The size of those gaps can be controlled by process parameters.

[0216] In one embodiment, foaming step ii) is carried out in case of XPS foams at a temperature ranging from 180 to 240°C, e.g. from 190 to 230°C. Preferably, foaming step ii) is carried out at a temperature of 190 to 220°C. In case of EPS foams the temperature of the steam of the usually applied hot water steam process (controlled by the steam pressure) can be in the range of 100 to around 150 to 160°C for both, the pre-expansion of the micro granules and the molding step.

[0217] It is appreciated that foaming step ii) may be performed in combination with molding. During molding, pressure may be applied to force the composition into the defined shape of the mold, such that the composition is in contact with all areas of the mold, and the composition is foamed in the mold, such that the product retains the desired shape.

[0218] Alternatively, the foamed article obtained in curing step ii) may be shaped into the desired shape.

[0219] Thus, the process may comprise further steps such as processing / forming the polystyrene foam in any desired shape. Such steps of processing / forming are well known to the skilled person and can be e.g. carried out by shaping the polystyrene foam. In one embodiment, the process for preparing the polystyrene foam comprises the steps of i) providing the polystyrene polymer formulation defined herein, ii) foaming the formulation of step i) such that a foam is formed, and iii) processing / forming the foam into a desired shape during or after step ii).

[0220] In particular, the density of the foam is sufficient. More precisely, the foam has a density from 15 to 100 g / l.

[0221] Additionally or alternatively, the mechanical properties of the foam are excellent. More precisely, the foam has a mechanical compression strength at 10% compression force, determined according to ISO EN 826, from 50 to 1000 N.

[0222] Additionally or alternatively, the pore structure of the foam is excellent. More precisely, the foam has a median pore circumference, measured by light microscopy, from 150 to 2000 pm.

[0223] In one embodiment, the foam has a density from 15 to 100 g / l, or a mechanical compression strength at 10% compression force, determined according to ISO EN 826, from 50 to 1000 N, or a median pore circumference, measured by light microscopy, from 150 to 2000 pm. Alternatively, the foam has a density from 15 to 100 g / l, and a mechanical compression strength at 10% compression force, determined according to ISO EN 826, from 50 to 1000 N, and a median pore circumference, measured by light microscopy, from 150 to 2000 pm.

[0224] In view of this, the present invention relates in another aspect to an article comprising the polystyrene foam. Preferably, the article is preferably selected from thermal insulation boards, acoustic insulation boards and packaging.

[0225] In a further aspect, the present invention relates to the use of a particulate earth alkali carbonate-comprising material, a particulate earth alkali phosphate-comprising material, a particulate hydroxide-comprising material and mixtures thereof as nucleating agent in a polystyrene polymer formulation, wherein the at least one nucleating agent is present in an amount from > 3 to 15 wt.-%, based on the total weight of the formulation.

[0226] The scope and interest of the invention will be better understood based on the following examples which are intended to illustrate certain embodiments of the present invention and are non- limitative.

[0227] Examples

[0228] 1. Measurement methods

[0229] In the following, measurement methods implemented in the examples are described.

[0230] Particle size distribution

[0231] The weight median particle size d5o(wt) and weight top cut particle size dgs(wt) is determined by the sedimentation method, which is an analysis of sedimentation behaviour in a gravimetric field. The measurement is made with a Sedigraph™ 5120, Micromeritics Instrument Corporation. The method and the instrument are known to the skilled person and are commonly used to determine grain size of fillers and pigments. The measurement is carried out in an aqueous solution of 0.1 wt.-% N34P2O7. The samples were dispersed using a high speed stirrer and sonicated. The processes and instruments are known to the skilled person and are commonly used to determine the particle size of fillers and pigments.

[0232] Specific surface area (SSA)

[0233] The specific surface area was measured via the BET method according to ISO 9277:2010 using nitrogen as adsorbing gas on a Micro me ritics ASAP 2460 instrument from Micro me ritics. The samples were pretreated in vacuum (10-5bar) by heating at 150°C for a period of 60 min prior to measurement.

[0234] Amount of surface-treatment layer

[0235] The amount of the treatment layer on the nucleating agent is calculated theoretically from the values of the BET of the untreated nucleating agent and the amount of the one or more compound(s) that is / are used for the surface-treatment. It is assumed that 100 % of the one or more compound(s) are present as surface treatment layer on the surface of the nucleating agent.

[0236] Residual moisture content

[0237] The residual moisture content was determined by thermogravimetric analysis (TGA). The equipment used to measure the TGA was the Mettler-Toledo TGA / DSC1 (TGA 1 STARe System) and the crucibles used were aluminium oxide 900 pl. The method consists of several heating steps under air (80 mL / min). The first step was a heating from 25 to 105°C at a heating rate of 20°C / minute (step 1), then the temperature was maintained for 10 minutes at 105°C (step 2). The residual moisture content is the cumulated weight loss after steps 1 and 2.

[0238] Mechanical properties

[0239] The mechanical properties of the foams were determined according to ISO EN 826.

[0240] Density

[0241] The density of the foams was calculated by determining of the foam volume, i.e. dimensions of the samples, and its mass. The density was then calculated by the following formula: density = mass / volume formula I

[0242] Pore structure

[0243] The median pore circumference of the foams was determined by light microscopy of Leica Microsystems.

[0244] Thermal conductivity

[0245] The thermal conductivity (lambda value) of the foams was determined with an equipment from NETZSCH (HFM 446). The foam specimen were cut to a size of 6 x 6 cm with a thickness of around 1 .5 cm. The measurement was performed after conditioning the specimen for 48h at 20°C and 50- 60% RH. The mean temperature for the thermal conductivity measurement was set to 20°C with a temperature gradient of 20 K (i.e. from 10°C to 30°C) and a heat rate of 2.0 K / min. The force of the sensors on the specimen were set to 12.0 N. The obtained lambda value is calculated and displayed by the device after finishing the measurement (reaching the equilibrium). 2. Examples

[0246] Inventive and comparative polystyrene polymer formulations were prepared by using the following nucleating agents and polystyrene comprising polymer material:

[0247] Nucleating agent 1 A to C

[0248] Talc is used in the polystyrene polymer formulation amounts of 2 wt.-% (Formulation 1A - comparative) 1 4 wt.-% (Formulation 1 B - comparative) 16 wt.-% (Formulation 1 C - comparative) Nucleating agent 2A to D

[0249] Nucleating agent 2 is a commercial grade natural ground calcium carbonate material (GCC) surface treated with 0.9 wt.-% stearic acid which is sold by Omya International AG.

[0250] Nucleating agent 2 is characterized by: a weight median particle size cfeo of 2 pm, a specific surface area (BET) of 3.8 m2 / g, and a moisture content of 0.08%.

[0251] Nucleating agent 2 is used in the polystyrene polymer formulation in amounts of 2 wt.-% (Formulation 2A - comparative) 1 4 wt.-% (Formulation 2B - inventive) 1 6 wt.-% (Formulation 2C - inventive) 1 8 wt.-% (Formulation 2D - inventive)

[0252] Nucleating agent 3A to D

[0253] Nucleating agent 3 is a commercial grade natural ground calcium carbonate material (GCC) surface treated with 0.8 wt.-% ASA which is sold by Omya International AG.

[0254] Nucleating agent 3 is characterized by: a weight median particle size cfeo of 2 pm, a specific surface area (BET) of 4.1 m2 / g, and a moisture content of 0.06%.

[0255] Nucleating agent 3 is used in the polystyrene polymer formulation in amounts of 2 wt.-% (Formulation 3A - comparative) 1 4 wt.-% (Formulation 3B - inventive) 1 6 wt.-% (Formulation 3C - inventive) I 8 wt.-% (Formulation 3D - inventive)

[0256] Nucleating agent 4A to D

[0257] Nucleating agent 4 is a commercial grade natural ground calcium carbonate material (GCC) surface treated with 1 .0 wt.-% stearic acid which is sold by Omya International AG.

[0258] Nucleating agent 4 is characterized by: a weight median particle size cfeo of 1 pm, a specific surface area (BET) of 8.2 m2 / g, and a moisture content of 0.11 %.

[0259] Nucleating agent 4 is used in the polystyrene polymer formulation in amounts of 2 wt.-% (Formulation 4A - comparative) 1 4 wt.-% (Formulation 4B - inventive) 1 6 wt.-% (Formulation 4C - inventive) I 8 wt.-% (Formulation 4D - inventive)

[0260] Polystyrene comprising polymer material

[0261] The polystyrene comprising polymer material used was a blend of 90 wt.-% of a GGPS grade, e.g. Styrolution® PS 158N of Ineos, with a MVR of 3.0 cm3 / 10min (200°C / 5kg) with 10 wt.-% of a HIPS grade, e.g. Styrolution® PS 486N of Ineos, with a MVR of 3.9 cm3 / 10min (200°C / 5kg).

[0262] The polystyrene polymer formulations were prepared by mixing and extruding the polystyrene comprising polymer material with the nucleating agent in the amounts defined above directly during the foaming extrusion process, as described in the next paragraph.

[0263] XPS foams were prepared from the above formulations by extrusion using a tandem twin- screw eguipment from Reifenhaeuser. The nucleating agent was added into the primary extruder via a side feeder in the amounts mentioned above. A combination of CO2 and ethanol has been used as blowing agents in a ratio 60 / 40 (in total around 1 .0 wt.-% on the polymer amount) and were injected via injectors in the primary extruder. The extrusion temperature in the primary extruder was set to 205°C. The pressure in the primary extruder was between 220 and 240 bar. The melt was cooled down continuously in the connected secondary extruder to a set die temperature of 105°C. The resulting melt at the die had a measured temperature of around 118°C and a pressure between 18 and 33 bar. The die dimensions were 30 mm x 1 mm. The expanded foam was calibrated by an upper and lower plate with a set distance of 50 mm. Regarding the foam density the target during the trials was to keep it as constant as possible for all foam samples to be able to compare the foam properties measured afterwards. The mechanical properties, density and pore structure of the obtained foams are set out in the following table 1 :

[0264] Table 1

[0265] It can be gathered from table 1 that foams prepared from the inventive polystyrene polymer formulations (formulations 2B-2D, 3B-3D and 4B-D4, have excellent mechanical properties, especially an excellent mechanical compression strength at 10% compression force compared to the comparative foams prepared from formulations 1A to 1C, formulation 2A, formulation 3A and formulation 4A.

[0266] In addition thereto, foams prepared from the inventive polystyrene polymer formulations (formulations 2B-2D, 3B-3D and 4B-D4, have excellent densities and pore structure compared to the comparative foams prepared from formulations 1A to 1C, formulation 2A, formulation 3A and formulation 4A.

Claims

Claims1 . Polystyrene polymer formulation comprising a polystyrene comprising polymer material and from > 3 to 15 wt.-%, based on the total weight of the formulation, of at least one nucleating agent selected from the group consisting of a particulate earth alkali carbonate-comprising material, a particulate earth alkali phosphate-comprising material, a particulate hydroxide-comprising material and mixtures thereof.

2. The polystyrene polymer formulation according to claim 1 , wherein the at least one nucleating agent is selected from the group consisting of natural ground calcium carbonate, precipitated calcium carbonate, surface-modified calcium carbonate, apatite, magnesium carbonate, hydromagnesite, dolomite, brucite, precipitated magnesium hydroxide, aluminium hydroxide and mixtures thereof, preferably natural ground calcium carbonate, precipitated calcium carbonate and mixtures thereof, and most preferably natural ground calcium carbonate.

3. The polystyrene polymer formulation according to claim 1 or 2, wherein the at least one nucleating agent has a weight median particle size cfeo value, measured by the sedimentation method, ranging from 0.3 to 5.5 pm, preferably from 0.5 to 4.0 pm and most preferably from 0.7 to 3.5 pm.

4. The polystyrene polymer formulation according to any one of claims 1 to 3, wherein the formulation comprises the at least one nucleating agent in an amount ranging from > 3 to 10 wt.-%, preferably from 4 to 10 wt.-% based on the total weight of the formulation.

5. The polystyrene polymer formulation according to any one of claims 1 to 4, wherein the at least one nucleating agent is treated with at least one surface-treatment agent selected from the group consisting ofI) a phosphoric acid ester blend of one or more phosphoric acid mono ester and / or salts thereof and / or one or more phosphoric acid di-ester and / or salts thereof, and / orII) at least one saturated or unsaturated aliphatic linear or branched carboxylic acid and / or salts thereof, preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C4 to C24 and / or a salt thereof, more preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C12 to C20 and / or a salt thereof, most preferably at least one aliphatic carboxylic acid having a total amount of carbon atoms from C16 to C18 and / or a salt thereof and / orIII) at least one mono-substituted succinic anhydride consisting of succinic anhydride mono-substituted with a group selected from a linear, branched, aliphatic and cyclic group having a total amount of carbon atoms from at least C2 to C30 in the substituent and / or salts thereof, and / orIV) at least one polydialkylsiloxane, andV) mixtures of one or more materials according to I) to IV).

6. The polystyrene polymer formulation according to claim 5, wherein the at least one surfacetreatment agent is present on the at least one nucleating agent in an amount ranging from 0.5 to 4.5 wt.-% based on the total weight of the at least one nucleating agent.

7. The polystyrene polymer formulation according to any one of claims 1 to 6, wherein the entirety of the polymer material consists of polystyrene.

8. The polystyrene polymer formulation according to any one of claims 1 to 7, wherein the polymer formulation further comprises one or more additives selected from the group comprising crosslinking agents, colouring pigments, filler, fibers, dyes, waxes, lubricants, oxidative- and / or UV- stabilizers, adhesion promoter, antioxidants, process stabilizers, flame retardants, anti-dripping agents, blowing agents, processing aids and mixtures thereof.

9. The polystyrene polymer formulation according to any one of claims 1 to 8, wherein the polymer formulation is a foam formulation.

10. A polystyrene foam comprising a polystyrene comprising polymer material and from > 3 to 15 wt.-%, based on the total weight of the formulation, of at least one nucleating agent selected from the group consisting of a particulate earth alkali carbonate-comprising material, a particulate earth alkali phosphate-comprising material and mixtures thereof.11 . The polystyrene foam according to claim 10, wherein the foam has a density from 15 to100 g / l, and / or a mechanical compression strength at 10% compression force, determined according to ISO EN 826, from 50 to 1000 N, and / or a median pore circumference, measured by light microscopy, from 150 to 2000 pm.

12. The polystyrene foam according to claim 10 or 11 being a XPS foam or an EPS foam.

13. The polystyrene foam according to any one of claims 10 to 12, wherein the foam is obtained by foaming the polystyrene polymer formulation of any one of claims 1 to 9.

14. A process for preparing a polystyrene polymer formulation as defined in any one of claims 1 to 9, wherein the process comprises the steps of a) providing a polystyrene comprising polymer material, b) providing from > 3 to 15 wt.-%, based on the total weight of the formulation, of at least one nucleating agent selected from the group consisting of a particulate earth alkali carbonate- comprising material, a particulate earth alkali phosphate-comprising material and mixtures thereof, and c) contacting the components of step a) and step b) and optional additives in any order such that a polystyrene polymer formulation is formed.

15. A process for preparing a polystyrene foam as defined in any one of claims 10 to 13, wherein the process comprises the steps of i) providing the polystyrene polymer formulation according to any one of claims 1 to 9, and ii) foaming the formulation of step i) such that a foam is formed.

16. Article, preferably thermal insulation boards, acoustic insulation boards and packaging, comprising a polystyrene foam according to any one of claims 10 to 13.

17. Use of a particulate earth alkali carbonate-comprising material, a particulate earth alkali phosphate-comprising material, a particulate hydroxide-comprising material and mixtures thereof as nucleating agent in a polystyrene polymer formulation, wherein the at least one nucleating agent is present in an amount from > 3 to 15 wt.-%, based on the total weight of the formulation.

Images