A thermoplastic composition comprising PBAT, articles and stone paper containing the same, and a method for the production of a stone paper

Abstract

The invention relates to a thermoplastic composition comprising A) polybutylene adipate terephthalate (PBAT), B) CaCO3 powder, C) one or more citric acid triesters, and optionally D) optional auxiliary components, wherein the components A) to D) add up to 100 weight-%. The invention further relates to article comprising such compositions, a stone paper comprising a sheet structure consisting of the thermoplastic composition, and a method for the manufacture of such stone paper.

Description

[0001] Description

[0002] A thermoplastic composition comprising PBAT, articles and stone paper containing the same, and a method for the production of a stone paper

[0003] Field of the invention

[0004] The invention relates to a thermoplastic composition comprising polybutylene adipate terephthalate (PBAT), articles and stone paper containing a composition comprising PBAT, and to a method for the production of a stone paper containing a composition comprising PBAT.

[0005] Background art

[0006] Stone paper, also referred to as limestone paper, rock paper, mineral paper or rich mineral paper, is a type of strong and durable paper-like material typically manufactured from calcium carbonate bonded with a varying amount of a thermoplastic resin, wherein in most cases this resin is high-density polyethylene (HDPE). More generally, any type of paper containing a high percentage of grounded rocks or stones, i.e. a mineral powder, may be referred to as stone paper.

[0007] While the first types of stone paper consisting of paper or cardboard surface-treated with gypsum and limestone powder, clay, oils and metal oxides date back to the nineteenth century, the „modern“ stone paper as known today and as, for instance, disclosed in the patent EP0945244 B1 , is commercially available since the 1990s.

[0008] Some benefits of such stone papers when compared to conventional papers are that the stone paper sheets are water-resistant, they are tearproof, they do not contain natural fibers and do thus not contribute to deforestation or require cultivation of fiber plants for the sake of paper production. Further, the water consumption in the production process is much lower than in the production of conventional paper. In addition, the stone paper sheets can be well-printable with offset printing machines.

[0009] Stone paper is thus beneficially applied for stationery, leaflets, posters, books, magazines, bags, packaging, wallpaper, adhesives, tags, in-mould labels, plates, trays, containers, and maps, among other uses.

[0010] However, although the conventional stone paper referred to above already displays a number of benefits over traditional paper and cardboard, it still has some disadvantages and flaws.

[0011] Foremost, unless stone paper waste material of conventional polyethylene-based stone paper is collected for recycling, it has undesired properties insofar as the material is not biologically degradable, but, as for instance polyethylene (PE) packings and foils, is degraded by UV sunlight and mechanical friction in the environment, resulting in the formation of microplastic particles, which are considered to have a strongly negative environmental impact.

[0012] Problem to be solved

[0013] The conventional stone paper types mainly consisting of calcium carbonate and polyethylene displaying the above-cited benefits decompose under the influence of UV light. Typically, they are photodegradable within 14-18 months of sunlight exposure, but in this process, the material is not broken down entirely and does not return to the environment like traditional paper, and accordingly it is not truly biodegradable. To the contrary, the decomposition of conventional stone paper upon UV irradiation results in the generation of microplastic particles, which is an eminent environmental threat. Further, the production of PE thermoplastic resins mostly relies on fossil raw materials instead of renewable raw materials, which results in a net release of CO2 when stone paper waste materials are disposed by incineration. Accordingly, when leaving aside the lower water consumption in the production process when compared to conventional paper, unless it is collected for recycling, traditional stone paper does not display particularly environmentally benign properties. From a technical perspective, conventional thermoplastic compositions used in the production of stone papers do not provide optimal material properties for many applications. For example, PE-based stone papers usually do not display the laser-printability desired for stone papers useful in the applications as intended for the compositions and stone papers according to this invention, and wrinkle upon printing.

[0014] The problem to be solved by the present invention is the provision of thermoplastic compositions as well as articles and stone papers comprising the same which are manufactured from environmentally friendly and regenerative starting materials, which are biodegradable, and which at the same time display very good material properties regarding water-resistance, tear-resistance, workability, machinability and printability. Further, the thermoplastic compositions, articles and stone papers are hardly inflammable and coldresistant to -30 °C.

[0015] Summary of the invention

[0016] The above problem is solved by the provision of a thermoplastic composition comprising polybutylene adipate terephthalate (PBAT), articles containing the thermoplastic composition comprising PBAT, a stone paper containing the thermoplastic composition comprising PBAT, and a method for the manufacture of stone paper containing the thermoplastic composition comprising PBAT, respectively.

[0017] The invention relates to a thermoplastic composition comprising the components A) 15 to 53 weight-% polybutylene adipate terephthalate (PBAT), preferably 15 to 45 weight -% PBAT, more preferably 22 to 38 weight-% PBAT, still more preferably 26 to 34 weight-% PBAT,

[0018] B) 42 to 82 weight-% CaCCh powder, preferably 42 to 75 weight-% CaCCh powder, more preferably 42 to 67 weight-% CaCCh powder, still more preferably 48 to 63 weight-% CaCCh powder, most preferably 52 to 57 weight-% CaCCh powder,

[0019] C) 0.5 to 20 weight-% of one or more citric acid triesters, preferably 5 to 20 weight-%, more preferably 10 to 19 weight-%, still more preferably 11 to 18 weight-%, and most preferably 12 to 17 weight-% of one or more citric acid triesters,

[0020] D) optionally up to 10 weight-% of auxiliary compounds, preferably up to 5 weight-% of auxiliary compounds, more preferably up to 2 weight-% auxiliary compounds, even more preferably up to 0.5 weight-% auxiliary compounds; most preferably no further auxiliary compounds, wherein the components A) to D) add up to 100 weight-%.

[0021] In further aspects, the invention relates to an article comprising the above thermoplastic composition, a stone paper comprising at least one sheet structure having a thickness of 25 |_im to 2 mm, preferably 50 .m to 1 mm, more preferably 60 .m to 750 .m, most preferably 75 to 400 .m, wherein the sheet structure consists of the above thermoplastic composition, and to a method for the manufacture of stone paper comprising the steps of mixing the components of the above thermoplastic composition, feeding the mixture to a calander machine or to a blow-film device and forming a sheet structure of the composition by rolling and optionally stretching.

[0022] Detailed description of the invention

[0023] According to the invention, the thermoplastic composition comprising PBAT is characterized as described in the following embodiments.

[0024] The present invention generally relates to a thermoplastic composition comprising the components

[0025] A) 15 to 53 weight-% polybutylene adipate terephthalate (PBAT), preferably 15 to 45 weight -% PBAT, more preferably 22 to 38 weight-% PBAT, still more preferably 26 to 34 weight-% PBAT,

[0026] B) 42 to 82 weight-% CaCCh powder, preferably 42 to 75 weight-% CaCCh powder, more preferably 42 to 67 weight-% CaCCh powder, still more preferably 48 to 63 weight-% CaCCh powder, most preferably 52 to 57 weight-% CaCCh powder, C) 0.5 to 20 weight-% of one or more citric acid triesters, preferably 5 to 20 weight-%, more preferably 10 to 19 weight-%, still more preferably 11 to 18 weight-%, and most preferably 12 to 17 weight-% of one or more citric acid triesters,

[0027] D) optionally up to 10 weight-% of auxiliary compounds, preferably up to 5 weight-% of auxiliary compounds, more preferably up to 2 weight-% auxiliary compounds, even more preferably up to 0.5 weight-% auxiliary compounds; most preferably no further auxiliary compounds, wherein the components A) to D) add up to 100 weight-%.

[0028] According to the invention, a thermoplastic composition is a material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling. It is desired in view of its applications as stone paper or in diverse articles that the thermoplastic composition of the present invention is form-stable when handled at room temperature, below room temperature or at slightly elevated temperatures, i.e. temperatures up to 100 °C, preferably up to 120 °C, but can be formed by rolling, stretching, moulding and casting at higher temperatures. The compositions according to the invention are usually processed at a temperature of 130 °C to 180 °C. The thermoplastic property of the composition is due to the presence of the PBAT polymer component and can be modulated by the amount and kind of PBAT comprised by the composition, but also depends on the amount and type of CaCOs powder particles B), of the one or more citric acid esters C), and by optional auxiliary compounds present in the composition.

[0029] The term PBAT as used in this application refers to polybutylene adipate terephthalate, a random copolyester of adipic acid, 1 ,4-butanediol and terephthalic acid building blocks. Therein, the material is not restricted to a specific dispersity of the polymer chain lengths or chain structuring regarding the butylene terephthalate (BT) polyester building blocks and butylene adipate (BA) polyester building blocks. While there is no general restriction with regard to the average molecular weight of the PBAT used, in view of the desired thermoplastic properties the number average molecular weight is preferably at least 10.0 kg / mol, and preferably not more than 200.0 kg / mol. The amount of BT units in mol-%, based on the total molar amount of BT units and BA units in the PBAT polymer resin, is preferably in the range of 5 to 95 mol-%, more preferably of 10 to 90 mol-%, even more preferably 25 to 75 mol-%. According to the invention, it is preferred that PBAT is used as sole thermoplastic polymer in the composition, which excludes the use of blends of PBAT with other polymers. Accordingly, the polymer used is PBAT, which as far as technically possible consists exclusively of BA and BT building blocks. Preferably, the BT and and BA units constitute at least 95 weight-% of the PBAT, more preferably at least 97 weight-%, even more preferably at least 98 weight-%, still more preferably 99 weight-%, and most preferably more than 99 weight-% relative to the overall weight of the PBAT component.

[0030] The composition according to the present invention comprises CaCCh powder as inorganic particulate component, which is typically obtained by grinding minerals and carbonate rocks such as limestone, chalk, calcite or eggshells and gastropod shells, or which is obtained as precipitated calcium carbonate (PCC). Accordingly, the term CaCOs powder according to the invention is defined as particulate matter comprising at least 85 weight-% of CaCCh, more preferably at least 90 weight-%, even more preferably at least 95 weight-% of CaCCh and still more preferably at least 98 weight-% relative to the overall weight of the CaCCh powder, wherein the remaining amount of matter of the CaCCh powder component is an inorganic material. Most preferably, the CaCCh content of the CaCCh powder is 99 weight-% or above. In particular for food applications, it is preferred that the CaCCh content of the CaCCh powder is 99 weight-% or above, even more preferably 99.5 weight-% or above. Such CaCCh powder is preferably a precipitated CaCCh powder.

[0031] According to the invention, the CaCCh powder preferably has a d95 particle diameter as determined by a technique generally used in the art, preferably by laser diffraction, for example by using a Malvern Mastersizer 3000 laser diffraction system using wet dispersion, of 0.5 to 400 .m, preferably of 1 to 100 .m, more preferably 2 to 80 .m, even more preferably 3 to 60 .m, and still more preferably of 4 to 40 .m, and further preferably of 7 to 20 .m.

[0032] With regard to the thermoplastic composition of the invention, the term “weight-%” refers to the mass of a specific component in relation to the overall mass of the composition.

[0033] According to the invention, the term “citric acid triesters” refers to derivatives of citric acid in which all three carboxylic groups are esterified, i.e. to citric acid esters having the general structure (I) wherein

[0034] R1, R2and R3may be the same or different from each other, preferably they are the same, and R1, R2and R3are selected from C1-C16 organyl residues, preferably from C1-C16 alkyl groups, more preferably from methyl, ethyl, propyl and butyl groups, and R4is selected from H and an acyl group of the formula -C(O)-R5, wherein R5is a C1-C24 hydrocarbyl group.

[0035] Preferably, R5is a C1-C24 alkyl group, more preferably a C1-C24 n-alkyl group, even more preferably a C1 to C8 n-alkyl group, most preferably a methyl group, i.e. , most preferably the acyl group is an acetyl group.

[0036] As optional auxiliary compounds D), any kind of component known in the art as additive for thermoplastic polymer compositions may be added. Specifically, the thermoplastic composition of the invention may comprise compounds acting as colorants, preservatives, binders, antioxidants, light stabilizers, antistatic agents and plasticizers.

[0037] While such auxiliary compounds may be added in view of the requirements of specific applications of the thermoplastic composition, the absence of auxiliary components D) is preferred according to the invention, i.e. preferably the components A), B) and C) add up to 100 weight-% of the thermoplastic composition.

[0038] In an embodiment of the invention, the composition comprises the components

[0039] A) 15 to 45 weight -% PBAT, preferably 22 to 38 weight-% PBAT, more preferably 26 to 34 weight-% PBAT,

[0040] B) 42 to 67 weight-% CaCCh powder, preferably 48 to 63 weight-% CaCCh powder, more preferably 52 to 57 weight-% CaCCh powder,

[0041] C) 5 to 20 weight-%, preferably 10 to 19 weight-%, more preferably 11 to 18 weight-%, and most preferably 12 to 17 weight-% of one or more citric acid triesters,

[0042] D) optionally up to 10 weight-% of auxiliary compounds, preferably up to 5 weight-% of auxiliary compounds, more preferably up to 2 weight-% auxiliary compounds, even more preferably up to 0.5 weight-% auxiliary compounds; most preferably no further auxiliary compounds, wherein the components A) to D) add up to 100 weight-%.

[0043] More preferred according to the embodiment, the composition comprises

[0044] A) 22 to 38 weight-% PBAT,

[0045] B) 48 to 63 weight-% CaCCh powder, and

[0046] C) 10 to 19 weight-% of one or more citric acid triesters, preferably 11 to 18 weight-% of one or more citric acid triesters, even more preferably 12 to 17 weight % of one or more citric acid triesters,

[0047] D) and up to 5 weight-% of auxiliary compounds, more preferably up to 2 weight-% auxiliary compounds, even more preferably up to 0.5 weight-% auxiliary compounds, wherein the components A) to D) add up to 100 weight-%. According to the embodiment, it is preferred that the CaCCh powder has a particle diameter d95 of 1 to 100 .m, more preferably of 2 to 60 .m. It is further preferred according to the embodiment that the component C) is a tributyl or triethyl citric acid ester, most preferably selected from triethyl citric acid ester and acetyl tributyl citric acid ester. Preferably, the components A), B) and C) add up to 100 weight-%.

[0048] In another embodiment, the composition comprises

[0049] A) 15 to 53 weight-% PBAT, preferably 18 to 50 weight-% PBAT,

[0050] B) 48 to 82 weight-% CaCCh powder, and

[0051] C) 0.5 to 2.0 weight-% of one or more citric acid triesters, preferably 0.7 to 1.7 weight-% of one or more citric acid triesters, even more preferably 0.8 to 1 .5 weight-% of one or more citric acid triesters, and

[0052] D) up to 5 weight-% of auxiliary compounds, more preferably up to 2 weight-% auxiliary compounds, even more preferably up to 0.5 weight-% auxiliary compounds, wherein the components A) to D) add up to 100 weight-%.

[0053] According to this embodiment, it is also preferred that the CaCCh powder has a particle diameter d95 of 1 to 100 .m, more preferably of 2 to 60 .m. It is further preferred according to the embodiment that the component C) is a tributyl or triethyl citric acid ester, most preferably selected from triethyl citric acid ester and acetyl tributyl citric acid ester. Preferably, the components A), B) and C) add up to 100 weight-%.

[0054] The composition of this embodiment shows a particularly low leaching of the citric acid triester compound C), which may be desirable in some applications. According to the embodiment, it is preferred that the composition comprises 50 weight-% or more of CaCCh powder, more preferably 60 weight-% or more CaCCh powder, and most preferably 70 weight-% or more of CaCCh powder. Accordingly, it is preferred that the amount of PBAT is 45 weight-% or lower, more preferably 40 weight-% or lower, and still more preferably 35 weight-% or lower.

[0055] In such composition, it is preferred that the composition comprises 0.5 to 1 .5 weight-% of the citric acid triester compound C) when the composition comprises 48 to 60 weight-% of CaCCh, powder, while it is preferred that the composition comprises 1.0 to 2.0 weight-% of the citric acid triester compound C) when the composition comprises 60 weight-% to 82 weight-% of CaCCh powder.

[0056] In a particularly preferred embodiment, the composition comprises

[0057] A) 36.5 to 51 .5 weight-% PBAT, B) 48 to 60 weight-% CaCCh powder, and

[0058] C) 0.5 to 1 .5 weight-% of one or more citric acid triesters, preferably 0.6 to 1 .4 weight-% of one or more citric acid triesters, even more preferably 0.7 to 1 .3 weight-% of one or more citric acid triesters, and

[0059] D) up to 2 weight-% auxiliary compounds, preferably up to 0.5 weight-% auxiliary compounds, wherein the components A) to D) add up to 100 weight-%.

[0060] Preferably, the components A) to C) add up to 100 weight-%.

[0061] In another particularly preferred embodiment, the composition comprises

[0062] A) 15.0 to 39.0 weight-% PBAT,

[0063] B) 60 to 82 weight-% CaCCh powder, and

[0064] C) 1 .0 to 2.0 weight-% of one or more citric acid triesters, preferably 0.6 to 1 .4 weight-% of one or more citric acid triesters, even more preferably 0.7 to 1 .3 weight-% of one or more citric acid triesters, and

[0065] D) up to 2 weight-% auxiliary compounds, preferably up to 0.5 weight-% auxiliary compounds, wherein the components A) to D) add up to 100 weight-%.

[0066] According to the embodiment, it is further preferred that the amount of CaCCh powder is in the range of 65 to 75 weight-% of CaCCh powder.

[0067] It is also preferred according to the embodiment that the components A) to C) add up to 100 weight-%.

[0068] In a specific embodiment according to the invention, the thermoplastic composition consists of

[0069] A) 43.8 to 51.5 weight-% of PBAT,

[0070] B) 48 to 55 weight-% of CaCCh powder having a particle diameter d95 of 1 to 100 .m, more preferably of 2 to 60 .m,

[0071] C) 0.5 to 1.2 weight-% of a citric acid triester compound, preferably triethyl citric acid ester, tributyl citric acid ester, acetyl triethyl citric acid ester or acetyl tributyl citric acid ester.

[0072] In another specific embodiment according to the invention, the thermoplastic composition consists of

[0073] A) 18.0 to 34.0 weight-% of PBAT,

[0074] B) 65 to 80 weight-% of CaCCh powder having a particle diameter d95 of 1 to 100 .m, more preferably of 2 to 60 .m,

[0075] C) 1 .0 to 2.0 weight-% of a citric acid triester compound, preferably triethyl citric acid ester, tributyl citric acid ester, acetyl triethyl citric acid ester or acetyl tributyl citric acid ester. In a further embodiment according to the invention, the component C) of the composition according to the invention is selected from trimethyl, triethyl, tripropyl or tributyl citric acid ester, wherein the hydroxyl group of the citric acid ester is optionally acylated.

[0076] The compounds selected as component C) are environmentally benign plasticizers which are either commercially available or may be produced easily at low cost. With regard to the composition of the invention, they provide superior material properties such as improved workability, in particular improved miscibility of the CaCCh powder and the PBAT. Furthermore, these plasticizers allow the omission of TiC>2, which is often used as plasticizer and whitening particle in stone paper composition, and of other bleaching agents as well.

[0077] In another embodiment according to the invention, the component C) of the composition according to the invention is an acylated citric acid ester, preferably an acetylated citric acid ester.

[0078] By the acylation of the hydroxy group of the citric acid ester, the polarity of the compound may be modified, and the properties of the composition may be tuned further.

[0079] While the acyl group is not particularly limited, it is preferred according to the embodiment that the acyl groups have the structural formula C(O)-R5with R5being selected from C1-C24 alkyl groups, more preferably from C1-C24 n-alkyl groups, even more preferably from C1 to C8 n- alkyl groups, and most preferably R5is a methyl group, i.e. , most preferably the acyl group is an acetyl group.

[0080] In a preferred embodiment according to the invention, the component C) is selected from the group consisting of triethyl citric acid ester and acetyl tributyl citric acid ester, preferably component C) is acetyl tributyl citric acid ester.

[0081] These preferred components C) have been found to be particularly useful as plasticizers in the composition according to the invention and thus provide improved workability to the composition while rendering the use of further other additives and auxiliary agents obsolete or optional. In addition, these compounds C) are readily available, biologically degradable and and environmentally benign at the same time.

[0082] In another preferred embodiment according to the invention, the thermoplastic composition consists of the components A), B) and C).

[0083] According to this embodiment, no further additives or auxiliaries D) are added to the composition, meaning that the components A), B) and C) add up to 100 weight-%, which results in a composition that is fully biologically degradable. Further, the use of potentially harmful or irritant substances which may leach from articles produced from the composition is thus avoided, which is an advantage for many applications beyond the environmental protection aspect, especially in foodstuff applications. At the same time, the composition consisting of the components A), B) and C) displays the material properties required for the desired technical applications.

[0084] According to this embodiment, it is preferred that the composition consists of the components

[0085] A) 22 - 38 weight- % PBAT,

[0086] B) 48 - 63 weight-% CaCCh powder, and

[0087] C) 10 - 19 weight-% of one or more citric acid triesters, further preferably it consists of

[0088] A) 25 - 35 weight-% PBAT,

[0089] B) 50 - 60 weight-% CaCCh powder, and

[0090] C) 11 - 18 weight-% of one or more citric acid triesters, and even further preferably it consists of

[0091] A) 27 - 33 weight-% PBAT,

[0092] B) 52 - 57 weight-% CaCCh powder, and

[0093] C) 13 - 17 weight-% of one or more citric acid triesters.

[0094] It is also preferred that the composition consist of the components

[0095] A) 36.5 to 51.5 weight-% PBAT,

[0096] B) 48 to 60 weight-% CaCCh powder, and

[0097] C) 0.5 to 1.5 weight-% of one or more citric acid triesters, or the composition consists of the components

[0098] A) 15.0 to 39.0 weight-% PBAT,

[0099] B) 60 to 82 weight-% CaCCh powder, and

[0100] C) 1 .0 to 2.0 weight-% of one or more citric acid triesters.

[0101] In these specific compositions, the amounts of components A), B) and C) add up to 100 weight- % of the composition.

[0102] Therein, the d95 particle size of the CaCCh powder is preferably in the range of 0.5 to 100 .m, more preferably in the range of 1 to 70 .m, even more preferably in the range of 2 to 60 .m, and most preferably in the range of 3 to 40 .m. The component C) therein is preferably a citric acid ester of the general structure (I) wherein R1, R2and R3are independently methyl, ethyl, propyl or butyl groups, or an acetylated citric acid ester wherein R1, R2and R3are methy, ethyl, propyl or butyl group, most preferably the component C) is acetylated tributyl citric acid ester or triethyl citric acid ester. In another embodiment according to the invention, the composition comprises an auxiliary component D) of 0.1 to 10 weight-%, preferably 0.5 to 8 weight-%, more preferably 1 to 7 weight-%, even more preferably 2 to 6 weight-% of one or more auxiliary compounds, such as colorants, preservatives, binders, anti-oxidants, light stabilizers, antistatic agents and plasticizers, preferably selected from the group consisting of fatty acids, in particular stearic acid, mineral powder, in particular talcum powder, kaolin powder, or pigments.

[0103] By the addition of such auxiliary compounds known in the art, the properties of the thermoplastic composition may be further enhanced with regard to technical and mechanical properties, for example rigidity, durability, or with regard to optical and haptic appearance.

[0104] Additional plasticizers which are preferred according to the embodiment are fatty acids and fatty acid ester, in particular linear C8 to C26 fatty acids and fatty acid ester, more preferably linear saturated C8 to C26 fatty acids and fatty acid ester, most preferably stearic acid. Preferred esters of the C8 to C26 fatty acid esters cited above are methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, and octyl esters.

[0105] Mineral powders which may be added to the composition according to this embodiment are talcum powder, kaolin powder or mica powder.

[0106] In another aspect, the invention relates to an article comprising a thermoplastic composition as described in detail above, wherein the article is selected from sheets, cards, books, bags, moulded articles, boxes and containers, separator sheets, cream jars, artificial sausage skins or artificial casings for foodstuff, filaments for 3D printing and a granulate.

[0107] Due to the thermoplastic nature of the composition and its rheological properties when heated, the composition can be used in the production of various articles by methods for shaping and molding thermoplastic compositions known in the art. Preferred methods for producing articles comprising the thermoplastic composition include extrusion, molding and casting of the thermoplastic composition.

[0108] Further, the thermoplastic composition according to the invention can be provided in the form of filaments for 3D printing and as a granulate, which can be used as starting materials for products and articles comprising the thermoplastic composition comprising PBAT according to the invention.

[0109] Filaments for 3D printing according to the invention consist of the thermoplastic composition described above, while the diameter of the filament and their length is not restricted in a particular way. Typical diameters of the filaments are between 1 mm and 5 mm, in particular 1.75 mm, 2.85 mm and 4 mm, and the filaments are produced by extrusion of the thermoplastic composition. Further, the thermoplastic composition can be provided as a granulate, wherein the size of the granules is not particularly restricted, but is preferably in the range of 1 mm to 5 mm diameter.

[0110] In a preferred embodiment according to the invention, the article comprising the thermoplastic composition according to the invention as defined above is an artificial sausage skin or artificial casing for foodstuff, which may be used for sausage-making and packaging of other foodstuff, such as stews, soups or porridges. The artificial sausage skins and artificial casings are characterized in that they can be produced by extrusion of the thermoplastic composition of the invention as known in the art to film tubes with a film thickness of 25 .m to 2 mm, preferably 50 .m to 1 mm, more preferably 60 .m to 750 .m, most preferably 75 .m to 400 .m as determined using a micrometer according to DIN EN ISO 534. Preferably, the artificial sausage skin or artificial casing for sausage-making or packaging foodstuff consist of the thermoplastic composition as defined above, more preferably they consist of the components A), B) and C) exclusively in view of their applicability in packaging foodstuff.

[0111] In another preferred embodiment according to the invention, the article comprising the thermoplastic composition according to the invention is a cream jar, i.e. a container for cosmetic or medical creams. The cream containers preferably have a round-shaped bottom side, and further preferably also a round-shaped top side. Typically, the top side is formed by a lid, more preferably a screw-lid, by which the cream jar can be closed reversibly. Such cream jars can be produced by molding or casting the thermoplastic composition according to the invention. Preferably, the cream jars consist of the thermoplastic composition as defined above, more preferably they consist of the components A), B) and C) exclusively. Preferably such a thermoplastic composition containing 60 weight-% of CaCCh powder B) or more and 1.0 to 2.0 weight-% of the citric acid triester C) as described above can be used in the production of cream jars.

[0112] In still another preferred embodiment according to the invention, the article comprising the thermoplastic composition according to the invention is a separator sheet, preferably a sausage separator sheet.

[0113] These separator sheets, which are preferably used in food applications, for instance as separator sheets for sausage, cold cut or cheese slices, preferably consist of the components A), B) and C) in order to provide food-safe separator sheets. In particular the compositions consisting of the components A), B) and C) as described in the embodiments above can be used for the production of the separator sheets. Such sheets are used to separate single slices of sausage or sliced roast meat, or for wrapping the same, and may also be used to separate single slices of cut cheese or to wrap cut cheese. The separator sheets are preferably of rectangular form and have a format of a= 3 cm x b = 3 cm to a = 60 cm x 40 cm, for instance 35 cm x 50 cm or 35 cm x 25 cm, or preferably to a = 30 cm x b = 30 cm, wherein the formats DIN A 4, DIN A5, DIN A 6, DIN A7, DIN A8 and DIN A 9 are preferred, and wherein the side lengths a and b may be varied independently within the ranges defined above, and have a thickness of 25 .m to 1 mm, preferably 50 .m to 750 .m, more preferably 60 .m to 400 .m, most preferably 75 .m to 250 .m as determined using a micrometer according to DIN EN ISO 534.

[0114] Preferably, the separator sheets consist of the thermoplastic composition as defined above, more preferably they consist of the components A), B) and C) exclusively. The separator slices further may be coated on one or both sides optionally, wherein a CaCCh-based coating is preferred.

[0115] The currently used separator sheets comprise at least two different layers, in most cases a paper layer and a polymer layer, which makes adequate waste separation and environmentally friendly waste disposal difficult.

[0116] The application of the separator sheets according to the invention is more environmentally benign, as the sheets are fully biologically degradable and do not require waste separation.

[0117] The articles comprising the thermoplastic composition according to the invention display good material properties regarding water-resistance, tear-resistance, workability, machinability and printability. Further, the articles according to the invention are hardly inflammable and coldresistant to -30 °C.

[0118] Cards, books and bags comprising the thermoplastic composition of the invention are mostly based on stone paper sheets as described in the following.

[0119] In still another aspect, the invention relates to a stone paper comprising at least one sheet structure having a thickness of 25 .m to 2 mm, preferably 50 .m to 1 mm, more preferably 60 |_im to 750 .m, most preferably 75 to 400 .m, wherein the sheet structure consists of a thermoplastic composition as described according to the embodiments above.

[0120] Stone paper, as described above, can replace fiber-based conventional paper as medium for writing and printing while displaying valuable mechanical properties such as tear resistance and resistance to humidity, but may also serve for packaging, construction and further applications. The stone paper according to the invention necessarily comprises a sheet structure having a thickness of 25 .m to 2 mm, preferably 50 .m to 1 mm, more preferably 60 .m to 750 .m, most preferably 75 to 400 .m, wherein the sheet structure consists of a thermoplastic composition according to the invention as disclosed above.

[0121] Therein, it is preferred that for thinner sheets having a thickness of 25 .m to 100 .m, a thermoplastic composition according to the invention with a lower ratio of CaCCh of 42 to 60 weight-% and a corresponding higher ratio of PBAT is used, as it provides a higher flexibility, while for thicker sheets having a thickness of 100 .m to 2 mm a higher content of CaCCh powder of 60 to 82 weight-% is considered to be preferable.

[0122] While the method for forming the sheet structure is not restricted in a particular manner, methods including an extrusion step are preferred, more preferably it is formed by blown film technique or flat film extrusion. Rolling and stretching may also be included in the production of the sheets comprised by the stone paper.

[0123] While the format of the sheets is not restricted in a particular manner, the sheets are preferably obtained in the form of a band with a fixed width, that may be stored on a roll and be cut to the desired form at a later point in time. The stone paper of the invention may in particular comprise sheets having a rectangular shape, in particular sheets having a format according to DIN A- Standard.

[0124] The thickness of the sheet structure is determined using a micrometer according to DIN EN ISO 534. The thickness of the sheet structure is determined in the absence of further coatings, laminates or the like.

[0125] In order to obtain a stone paper according to the invention, the sheet structure described above may optionally be further coated or laminated on one side or on both sides thereof.

[0126] In an embodiment, no further coating, laminate or film is added to the sheet structure obtained from the thermoplastic composition as described above.

[0127] In an embodiment of the invention, the stone paper further comprises a coating layer on one or both sides of the sheet structure, wherein the coating layer preferably comprises at least one coating powder selected from kaolin powder, chalk powder, talcum powder, calcium carbonate or marble powder, wherein the coating powder preferably has a d95 to d99 particle size of 0.05 .m to 2 .m, most preferably talcum powder having a d98 particle size of 0.1 .m to 0.4 .m, or a silicone composition, wherein it is further preferred that there is a coating layer on one side of the sheet structure.

[0128] According to the invention, the terms “particle size” and “particle diameter” may be used interchangeably. The amount of material added to the sheet structure to form a coating layer is not restricted in a particular manner, however, preferably an amount of 0.5 g to 50 g per m2is applied, more preferably 1 to 40, even more preferably 5 to 30, and still more preferably 10 to 25 g per m2.

[0129] In general, coating layers according to the invention may be starch coatings, which are starch solutions comprising further additives, and pigment coatings, which are pigment-containing paints.

[0130] Further, coatings comprising polymers, for example acrylates, and coatings comprising silicones may be applied.

[0131] Starch coatings according to the invention comprise starch, which are applied as an aqueous solution or slurry, or as dry powder.

[0132] Besides starch, the starch coating may comprise water, pigments, binders and thickeners. Preferably, the starch coating further comprises at least one pigment selected from lithopone, barium sulfate, zinc oxide, zinc sulfide, lead carbonate or calcium carbonate, most preferably calcium carbonate.

[0133] Pigment coatings according to the invention comprise at least one type of pigments, which are preferably selected from, lithopone, barium sulfate, zinc oxide, zinc sulfide, lead carbonate or calcium carbonate, most preferably calcium carbonate.

[0134] For some applications, especially for foodstuff applications, in particular for food packaging, calcium carbonate is the most preferred coating material, which may be applied as a dry powder, a slurry or in compositions such as starch coatings or pigment coatings comprising further constituents compatible with foodstuff applications.

[0135] Thus, the stone paper preferably further comprises a coating layer on one or both sides of the sheet structure, wherein the coating layer comprises calcium carbonate powder, and wherein the coating powder preferably has a d95 to d99 particle size of 0.05 .m to 2 .m, most preferably talcum powder having a d98 particle size of 0.1 .m to 0.4 .m, or a silicone composition comprising calcium carbonate powder. It is further preferred that there is a coating layer comprising calcium carbonate powder on one side of the sheet structure.

[0136] The pigment coatings optionally further comprise water, dispersants for pigments, in particular polyacrylates, binders, thickeners, rheological additives, and defoamers.

[0137] Pigment coatings according to the invention are applied as an aqueous solution or slurry, or as dry powder.

[0138] A particularly preferred coating comprises kaolin powder, an acrylate polymer acting as binder, calcium carbonate powder having a particle size below 1.5 .m, and polyvinyl alcohol.

[0139] It is preferred that the sheet structure of the stone paper is coated with such coating on one side, wherein 1 to 10 g per m2are applied. Such stone paper is characterized in that it displays particularly good laserprintability, while maintaining good mechanical and haptic properties, such as water-resistance, tear-resistance, workability, machinability and printability, low inflammability and cold resistance to -30 °C. The properties of the stone paper according to this embodiment can be further controlled and tuned by the choice and / or addition of specific additives.

[0140] The amount of coating per m2refers to the amount of coating material present in the final stone paper product, i.e. after drying of the coating and removal of excess coating material.

[0141] The coating layer may provide the stone paper with enhanced properties regarding haptic or optical appearance, printability and durability.

[0142] A preferred coating layer is selected to enhance the laser-printability of the stone paper sheets. According to the invention, it is preferred that there is a coating layer on one side of the sheet structure.

[0143] In an embodiment of the invention, the sheet thickness is in the range from 60 .m to 350 .m, more preferably 80 .m to 300 .m, most preferably 100 .m to 250 .m.

[0144] In another embodiment according to the invention, the sheet thickness is in the range of from 25 .m to 100 .m, and the sheet structure of the stone paper consists of a composition comprising

[0145] A) 36.5 to 51.5 weight-% PBAT,

[0146] B) 48 to 60 weight-% CaCCh powder, and

[0147] C) 0.5 to 1.5 weight-% of one or more citric acid triesters, preferably 0.6 to 1.4 weight-% of one or more citric acid triesters, even more preferably 0.7 to 1 .3 weight-% of one or more citric acid triesters, and

[0148] D) up to 2 weight-% auxiliary compounds, preferably up to 0.5 weight-% auxiliary compounds, wherein the components A) to D) add up to 100 weight-%, and preferably the components A) to C) add up to 100 weight-%.

[0149] Preferably, the sheet structure of the stone paper according to the embodiment consists of a composition consisting of the components

[0150] A) 36.5 to 51.5 weight-% PBAT,

[0151] B) 48 to 60 weight-% CaCCh powder, and

[0152] C) 0.5 to 1.5 weight-% of one or more citric acid triesters. According to this embodiment, the citric acid triester compound is preferably selected from triethyl citric acid ester, tributyl citric acid ester, acetyl triethyl citric acid ester or acetyl tributyl citric acid ester.

[0153] In still another embodiment according to the invention, the sheet thickness is in the range of from 100 .m to 2 mm, preferably 200 .m to 1 mm, and the sheet structure of the stone paper consists of a composition comprising

[0154] A) 15.0 to 39.0 weight-% PBAT,

[0155] B) 60 to 82 weight-% CaCCh powder, and

[0156] C) 1 .0 to 2.0 weight-% of one or more citric acid triesters, preferably 0.6 to 1.4 weight-% of one or more citric acid triesters, even more preferably 0.7 to 1 .3 weight-% of one or more citric acid triesters, and

[0157] D) up to 2 weight-% auxiliary compounds, preferably up to 0.5 weight-% auxiliary compounds, wherein the components A) to D) add up to 100 weight-%, and preferably the components A) to C) add up to 100 weight-%.

[0158] Preferably, the sheet structure of the stone paper according to the embodiment consists of a composition consisting of the components

[0159] A) 15.0 to 39.0 weight-% PBAT,

[0160] B) 60 to 82 weight-% CaCCh powder, and

[0161] C) 1 .0 to 2.0 weight-% of one or more citric acid triesters.

[0162] According to this embodiment, the citric acid triester compound is preferably selected from triethyl citric acid ester, tributyl citric acid ester, acetyl triethyl citric acid ester or acetyl tributyl citric acid ester.

[0163] The thermoplastic composition according to the invention allows the production of a wide range of sheet thicknesses, wherein the above-cited range of 60 .m to 350 .m, more preferably 80 |_im to 300 .m, most preferably 100 .m to 250 .m is preferred due to rendering the stone paper digitally printable, offset printable, stiffer and providing it with a higher hardness, which makes the stone paper particularly suitable for the use in the production of bags and boxes or for the use in cards, books and notebooks, all types of light packaging, laserprintable paper and plates for book covers.

[0164] In a preferred embodiment according to the invention, the sheet structure of the stone paper as described above consists of a composition comprising A) 22 to 38 weight-% PBAT, more preferably 26 to 34 weight-% PBAT,

[0165] B) 48 to 63 weight-% CaCCh powder, more preferably 52 to 57 weight-% CaCCh powder,

[0166] C) 5 to 20 weight-%, preferably 10 to 19 weight-%, more preferably 11 to 18 weight-%, even more preferably 12 to 17 weight-% of one or more citric acid triesters,

[0167] D) and optionally up to 5 weight-% of auxiliary compounds, more preferably up to 2 weight- % auxiliary compounds, even more preferably up to 0.5 weight-% auxiliary compounds, wherein the component C) is preferably selected from trimethyl, triethyl, tripropyl or tributyl citric acid ester, and wherein the hydroxyl group of the citric acid is optionally acylated, and wherein the components A) to D) add up to 100 weight-%.

[0168] Preferably, the components A) to C) add up to 100 weight-%.

[0169] In another preferred embodiment according to the invention, the sheet structure of the stone paper as described above consists of a composition comprising

[0170] A) 15 to 53 weight-% PBAT, preferably 18 to 50 weight-% PBAT,

[0171] B) 48 to 82 weight-% CaCCh powder, and

[0172] C) 0.5 to 2.0 weight-% of one or more citric acid triesters, preferably 0.7 to 1.7 weight-% of one or more citric acid triesters, even more preferably 0.8 to 1 .5 weight-% of one or more citric acid triesters, and

[0173] D) up to 5 weight-% of auxiliary compounds, more preferably up to 2 weight-% auxiliary compounds, even more preferably up to 0.5 weight-% auxiliary compounds, wherein the components A) to D) add up to 100 weight-%, and preferably A) to C) add up to weight-%.

[0174] According to the invention, the sheet structure can consist of any type of thermoplastic composition according to the invention as disclosed above. These sheet structures can have any further features as disclosed herein with regard to the stone paper containing the sheet structure comprising the thermoplastic composition as disclosed above.

[0175] In a further aspect, the invention relates to a method for the manufacture of stone paper comprising the steps of a) mixing the components A), B), C) and D) of the thermoplastic composition as described above, wherein optionally one or more further steps of mixing, compacting and smoothing may be performed, b) feeding the mixture of the components obtained in step a) to a calander machine, to a blow-film device or to a plate extrusion system through a feed device, c) forming a sheet structure of the composition for the production of stone paper, optionally comprising the steps of rolling and optionally stretching of the composition, wherein optionally one or more of these steps are performed repeatedly, and optionally d) applying a coating layer to one or both sides of the sheet structure obtained from step c) by a liquid coating process or a dry coating process, and further optionally e) applying a barrier film by bathing the product obtained from step c) or step d) in a dry or liquid coating process.

[0176] Mixing can be performed by any machine or apparatus capable of producing a homogeneous composition of the components A), B), C) and D), including ball mills, mixing machines, kneading machines, extruders, in particular twin screw extruders, and planetary mixers.

[0177] Compacting devices for compacting the composition and smoothing devices are known in the art. Likewise, any suitable calander device, blow-film device or plate extrusion device known in the art may be used for the production of the stone paper sheets.

[0178] Rolling of the films or sheets of the composition according to the invention in the above-defined process refers to the rolling of the extruded stone paper film by rollers, whereby devices with one, two or three, preferably two, rollers can be used. By rolling, the thickness of the stone paper film can be adjusted. Optionally, the film or sheets can then be cooled and / or rolled a second time to improve the surface properties.

[0179] According to the invention, stretching as used above means that thermoplastic films or sheets can be stretched in one direction longitudinally or transversely (monoaxially) or in both directions (biaxially). This allows the desired film thickness to be achieved and the weight per unit area to be reduced, as well as improving the mechanical properties, e.g. strength properties, increasing transparency, improving cold resistance and reducing gas permeability. Typically, the films obtained by film-blowing are stretched upon blowing and then cooled down and optionally rolled. For such process, commercially available film stretching lines may be used. Liquid coating processes for applying a coating layer may be selected from slot die coating, blade coating, dip coating, spray coating, roller coating and multiple coating by cascade or curtain coating, for example. In a dry coating process for applying a coating layer, stone paper sheets or films are heated, contacted with an adhesive in powder form, preferably a thermoplastic hot-melt adhesive, a dry coating powder, in particular powdered CaCCh or talcum, are applied to the surface of the film or sheet. Preferably, the film or sheet is then pressed and allowed to cool down and dry. For example, powder coating lines produced by Maschinenfabrik Herbert Meyer can be used for dry coating of stone paper sheets or films.

[0180] A barrier film is a thin coating layer which is non-permeable to water and / or oils, which may be an oil, a fatty acid, a fatty acid ester or a polymer coating.

[0181] In an embodiment according to the invention, in the method for the manufacture of stone paper the d95 particle size of the component B) is 90 .m or lower and the mixture of components in step b) is fed to a blow-film device or extrusion device, and step c) comprises rolling and stretching of the composition.

[0182] By such method, a stone paper displaying superior mechanical properties may be obtained. Preferably, the d95 particle size of the component (B) is 80 .m or lower, more preferably 60 |_im or lower, even more preferably 40 .m or lower and more than 1 .m, and most preferably 30 .m or lower and more than 2 .m.

[0183] It is preferred that the thickness of such stone paper sheets is relatively low, preferably in the range of 25 to 300 .m, more preferably in the range of 45 to 225 .m, even more preferably in the range of 60 to 200 .m, and most preferably in the range of 75 to 175 .m.

[0184] In another embodiment according to the invention, in the method for the manufacture of stone paper the d95 particle size of the component B) is 90 .m or higher and the mixture of components in step b) is fed to a calander device or a plate extrusion system, and step c) extrusion comprises rolling of the composition.

[0185] For the manufacture of stone paper comprising CaCCh powder having a particle size of 90 .m or higher, the use of a calander machine is beneficial, and thus products displaying superior mechanical properties, for example stiffness, and improved printability can be obtained. The thickness of the stone paper sheets obtained is relatively high, preferably in the range of 250 |_im to 2.5 mm, more preferably in the range of 300 .m to 1 mm, even more preferably in the range of 350 .m to 900 .m, and most preferably in the range of 400 .m to 800 .m. A further advantage of the method according to the embodiment is that CaCCh dust obtained from limestone in the production of cement may be used as CaCCh powder, which is thus easily available at a moderate price. In general, the PBAT used in the products and methods according to the invention can be PBAT provided by the recycling industry.

[0186] In a further embodiment according to the invention, in the method for the manufacture of stone paper a coating layer is applied to the product of step c), preferably in a dry or liquid coating process.

[0187] Applying a coating layer as disclosed above with regard to the stone paper according to the invention can improve the haptic properties of the stone paper and may in particular improve the printability of the stone paper sheets.

[0188] In still a further embodiment according to the invention, in the method for the manufacture of stone paper a barrier film is applied to the product of step c) or d), preferably in a dry or liquid coating process.

[0189] According to the invention, a barrier film is a thin coating layer which is non-permeable to water and / or oils, which may be an oil, a fatty acid, a fatty acid ester or a polymer coating. It is preferable that the barrier film is food-safe, i.e. it meets the requirements of the European Food Regulation for materials that may come into contact with food for consumption.

[0190] In the following, the preferred embodiments according to the invention are summarized.

[0191] List of preferred embodiments according to the invention

[0192] 1 . A thermoplastic composition comprising the components

[0193] A) 15 to 53 weight-% polybutylene adipate terephthalate (PBAT), preferably 15 to 45 weight -% PBAT, more preferably 22 to 38 weight-% PBAT, still more preferably 26 to 34 weight-% PBAT,

[0194] B) 42 to 82 weight-% CaCCh powder, preferably 42 to 75 weight-% CaCCh powder, more preferably 42 to 67 weight-% CaCCh powder, still more preferably 48 to 63 weight-% CaCCh powder, most preferably 52 to 57 weight-% CaCCh powder,

[0195] C) 0.5 to 20 weight-% of one or more citric acid triesters, preferably 5 to 20 weight-%, more preferably 10 to 19 weight-%, still more preferably 11 to 18 weight-%, and most preferably 12 to 17 weight-% of one or more citric acid triesters,

[0196] D) optionally up to 10 weight-% of auxiliary compounds, preferably up to 5 weight-% of auxiliary compounds, more preferably up to 2 weight-% auxiliary compounds, even more preferably up to 0.5 weight-% auxiliary compounds; most preferably no further auxiliary compounds, wherein the components A) to D) add up to 100 weight-%. 2. The thermoplastic composition according to embodiment 1 , wherein the composition comprises

[0197] A) 15 to 53 weight-% PBAT, preferably 18 to 50 weight-% PBAT,

[0198] B) 48 to 82 weight-% CaCCh powder, and

[0199] C) 0.5 to 2.0 weight-% of one or more citric acid triesters, preferably 0.7 to 1.7 weight-% of one or more citric acid triesters, even more preferably 0.8 to 1 .5 weight-% of one or more citric acid triesters, and

[0200] D) up to 5 weight-% of auxiliary compounds, more preferably up to 2 weight-% auxiliary compounds, even more preferably up to 0.5 weight-% auxiliary compounds, wherein the components A) to D) add up to 100 weight-%.

[0201] 3. The thermoplastic composition according to embodiment 1 or 2, wherein the composition comprises 50 weight-% or more of CaCCh powder, more preferably 60 weight-% or more CaCCh powder, and most preferably 70 weight-% or more of CaCCh powder.

[0202] 4. The thermoplastic composition according to any of the embodiments 1 to 3, wherein the composition comprises 0.5 to 1.5 weight-% of the citric acid triester compound C) when the composition comprises 48 to 60 weight-% of CaCCh, powder, and the composition comprises 1.0 to 2.0 weight-% of the citric acid triester compound C) when the composition comprises 60 weight-% to 82 weight-% of CaCCh powder.

[0203] 5. The thermoplastic composition according to any of the previous embodiments 1 to 4, wherein the composition comprises

[0204] A) 36.5 to 51.5 weight-% PBAT,

[0205] B) 48 to 60 weight-% CaCCh powder, and

[0206] C) 0.5 to 1 .5 weight-% of one or more citric acid triesters, preferably 0.6 to 1 .4 weight-% of one or more citric acid triesters, even more preferably 0.7 to 1.3 weight-% of one or more citric acid triesters, and

[0207] D) up to 2 weight-% auxiliary compounds, preferably up to 0.5 weight-% auxiliary compounds, wherein the components A) to D) add up to 100 weight-%, preferably the components A) to C) add up to 100 weight-%.

[0208] 6. The thermoplastic composition according to any of the previous embodiments 1 to 4, wherein the composition comprises

[0209] A) 15.0 to 39.0 weight-% PBAT, B) 60 to 82 weight-% CaCCh powder, and

[0210] C) 1.0 to 2.0 weight-% of one or more citric acid triesters, preferably 0.6 to 1.4 weight-% of one or more citric acid triesters, even more preferably 0.7 to 1 .3 weight-% of one or more citric acid triesters, and

[0211] D) up to 2 weight-% auxiliary compounds, preferably up to 0.5 weight-% auxiliary compounds, wherein the components A) to D) add up to 100 weight-%, preferably the components A) to C) add up to 100 weight-%.

[0212] 7. The thermoplastic composition according to any of the previous embodiments 1 to 5, wherein the composition consists of

[0213] A) 43.8 to 51 .5 weight-% of PBAT,

[0214] B) 48 to 55 weight-% of CaCCh powder having a particle diameter d95 of 1 to 100 .m, more preferably of 2 to 60 .m

[0215] C) 0.5 to 1.2 weight-% of a citric acid triester compound, preferably triethyl citric acid ester, tributyl citric acid ester, acetyl triethyl citric acid ester or acetyl tributyl citric acid ester.

[0216] 8. The thermoplastic composition according to any of the previous embodiments 1 to 4 or 6, wherein the composition consists of

[0217] A) 18.0 to 34.0 weight-% of PBAT

[0218] B) 65 to 80 weight-% of CaCCh powder having a particle diameter d95 of 1 to 100 .m, more preferably of 2 to 60 .m

[0219] C) 1 .0 to 2.0 weight-% of a citric acid triester compound, preferably triethyl citric acid ester, tributyl citric acid ester, acetyl triethyl citric acid ester or acetyl tributyl citric acid ester.

[0220] 9. A thermoplastic composition according to embodiment 1 , comprising the components

[0221] A) 15 to 45 weight -% PBAT, preferably 22 to 38 weight-% PBAT, more preferably 26 to 34 weight-% PBAT,

[0222] B) 42 to 67 weight-% CaCCh powder, preferably 48 to 63 weight-% CaCCh powder, more preferably 52 to 57 weight-% CaCCh powder,

[0223] C) 5 to 20 weight-%, preferably 10 to 19 weight-%, more preferably 11 to 18 weight-%, and most preferably 12 to 17 weight-% of one or more citric acid triesters,

[0224] D) optionally up to 10 weight-% of auxiliary compounds, preferably up to 5 weight-% of auxiliary compounds, more preferably up to 2 weight-% auxiliary compounds, even more preferably up to 0.5 weight-% auxiliary compounds; most preferably no further auxiliary compounds, wherein the components A) to D) add up to 100 weight-%.

[0225] 10. The thermoplastic composition according to embodiments 1 or 9, wherein the composition comprises

[0226] A) 22 to 38 weight-% PBAT,

[0227] B) 48 to 63 weight-% CaCCh powder, and

[0228] C) 10 to 19 weight-% of one or more citric acid triesters, preferably 11 to 18 weight- % of one or more citric acid triesters, even more preferably 12 to 17 weight-% of one or more citric acid triesters, and

[0229] D) up to 5 weight-% of auxiliary compounds, more preferably up to 2 weight-% auxiliary compounds, even more preferably up to 0.5 weight-% auxiliary compounds, wherein the components A) to D) add up to 100 weight-%.

[0230] 11 . The thermoplastic composition according to any of the embodiments 1 to 10, wherein the component C) is selected from trimethyl, triethyl, tripropyl or tributyl citric acid ester, and wherein the hydroxyl group of the citric acid ester is optionally acylated.

[0231] 12. The thermoplastic composition according to any of embodiments 1 to 11 , wherein the component C) is an acylated citric acid ester, preferably an acetylated citric acid ester.

[0232] 13. The thermoplastic composition according to any of embodiments 1 to 12, wherein the component C) is selected from the group consisting of triethyl citric acid ester and acetyl tributyl citric acid ester, preferably component C) is acetyl tributyl citric acid ester.

[0233] 14. The thermoplastic composition according to any of the previous embodiments 1 to 13, wherein the composition consists of the components A), B) and C).

[0234] 15. The thermoplastic composition according to any of the previous embodiments 1 to 14, wherein the composition comprises an auxiliary component D) of 0.1 to 10 weight-%, preferably 0.5 to 8 weight-%, more preferably 1 to 7 weight-%, even more preferably 2 to 6 weight-% of one or more auxiliary compounds, such as colorants, preservatives, binders, antioxidants, light stabilizers, antistatic agents and plasticizers, preferably selected from the group consisting of fatty acids, in particular stearic acid, mineral powder, in particular talcum powder, kaolin powder, or pigments. 16. An article comprising the thermoplastic composition according to any of the previous embodiments 1 to 15, wherein the article is selected from sheets, cards, books, bags, moulded articles, boxes and containers, separator sheets, cream jars, artificial sausage skins or artificial casings for foodstuff, filaments for 3D printing and a granulate.

[0235] 17. A stone paper comprising at least one sheet structure having a thickness of 25 .m to 2 mm, preferably 50 .m to 1 mm, more preferably 60 .m to 750 .m, most preferably 75 to 400 .m, wherein the sheet structure consists of a thermoplastic composition as defined in any of the previous embodiments 1-15.

[0236] 18. The stone paper according to embodiment 17, further comprising a coating layer on one or both sides of the sheet structure, wherein the coating layer comprises preferably at least one coating powder selected from kaolin powder, chalk powder, talcum powder , calcium carbonate or marble powder, wherein the coating powder preferably has a d95 to d99 particle size of 0.05 .m to 2 .m, most preferably talcum powder having a d98 particle size of 0.1 .m to 0.4 .m, or a silicone composition, wherein it is further preferred that there is a coating layer on one side of the sheet structure.

[0237] 19. The stone paper according to embodiment 17 or embodiment 18, wherein the sheet thickness is in the range from 60 .m to 350 .m, more preferably 80 .m to 300 .m, most preferably 100 .m to 250 .m.

[0238] 20. The stone paper according to any of the embodiments 17 to 19, wherein the sheet structure consists of a composition comprising

[0239] A) 22 to 38 weight-% PBAT, more preferably 26 to 34 weight-% PBAT,

[0240] B) 48 to 63 weight-% CaCCh powder, more preferably 52 to 57 weight-% CaCCh powder,

[0241] C) 5 to 20 weight-%, preferably 10 to 19 weight-%, more preferably 11 to 18 weight-%, even more preferably 12 to 17 weight-% of one or more citric acid triesters,

[0242] D) and optionally up to 5 weight-% of auxiliary compounds, more preferably up to 2 weight- % auxiliary compounds, even more preferably up to 0.5 weight-% auxiliary compounds, wherein the component C) is preferably selected from trimethyl, triethyl, tripropyl or tributyl citric acid ester, and wherein the hydroxyl group of the citric acid is optionally acylated, wherein the components A) to D) add up to 100 weight-%.

[0243] 21. The stone paper according to any of the embodiments 17-19, wherein the sheet structure consists of a composition comprising A) 15 to 53 weight-% PBAT, preferably 18 to 50 weight-% PBAT,

[0244] B) 48 to 82 weight-% CaCCh powder, and

[0245] C) 0.5 to 2.0 weight-% of one or more citric acid triesters, preferably 0.7 to 1.7 weight-% of one or more citric acid triesters, even more preferably 0.8 to 1 .5 weight-% of one or more citric acid triesters, and

[0246] D) up to 5 weight-% of auxiliary compounds, more preferably up to 2 weight-% auxiliary compounds, even more preferably up to 0.5 weight-% auxiliary compounds, wherein the components A) to D) add up to 100 weight-%.

[0247] 22. The stone paper according to any of the embodiments 17, 18 or 21 , wherein the sheet thickness is in the range of from 25 .m to 100 .m, and the sheet structure of the stone paper consists of a composition comprising

[0248] A) 36.5 to 51.5 weight-% PBAT,

[0249] B) 48 to 60 weight-% CaCCh powder, and

[0250] C) 0.5 to 1.5 weight-% of one or more citric acid triesters, preferably 0.6 to 1.4 weight-% of one or more citric acid triesters, even more preferably 0.7 to 1.3 weight-% of one or more citric acid triesters, and

[0251] D) up to 2 weight-% auxiliary compounds, preferably up to 0.5 weight-% auxiliary compounds, wherein the components A) to D) add up to 100 weight-%, and preferably the components A) to C) add up to 100 weight-%.

[0252] 23. The stone paper according to the previous embodiment 22, wherein the sheet structure of the stone paper consists of a composition consisting of the components

[0253] A) 36.5 to 51.5 weight-% PBAT,

[0254] B) 48 to 60 weight-% CaCCh powder, and

[0255] C) 0.5 to 1.5 weight-% of one or more citric acid triesters.

[0256] 24. The stone paper according to any of the embodiments 17, 18 or 21 , wherein the sheet thickness is in the range of from 100 .m to 2 mm, preferably 200 .m to 1 mm, and the sheet structure of the stone paper consists of a composition comprising

[0257] A) 15.0 to 39.0 weight-% PBAT,

[0258] B) 60 to 82 weight-% CaCCh powder, and

[0259] C) 1 .0 to 2.0 weight-% of one or more citric acid triesters, preferably 0.6 to 1.4 weight-% of one or more citric acid triesters, even more preferably 0.7 to 1.3 weight-% of one or more citric acid triesters, and D) up to 2 weight-% auxiliary compounds, preferably up to 0.5 weight-% auxiliary compounds, wherein the components A) to D) add up to 100 weight-%, and preferably the components A) to C) add up to 100 weight-%.

[0260] 25. The stone paper according to the previous embodiment 24, wherein the sheet structure of the stone paper consists of a composition consisting of the components

[0261] A) 15.0 to 39.0 weight-% PBAT,

[0262] B) 60 to 82 weight-% CaCCh powder, and

[0263] C) 1.0 to 2.0 weight-% of one or more citric acid triesters.

[0264] 26. A method for the manufacture of stone paper, comprising the steps of a) mixing the components A), B), C) and D) of the thermoplastic composition according to embodiments 1 to 15, wherein optionally one or more further steps of mixing, compacting and smoothing may be performed, b) feeding the mixture of the components obtained in step a) to a calander machine, to a blow-film device or to a plate extrusion system through a feed device, c) forming a sheet structure of the composition for the production of stone paper, optionally comprising the steps of rolling and optionally stretching of the composition, wherein optionally one or more of these steps are performed repeatedly, and optionally d) applying a coating layer to one or both sides of the sheet structure obtained from step c) by a liquid coating process or a dry coating process, and further optionally e) applying a barrier film by bathing the product obtained from step c) or step d) in a dry or liquid coating process. 27. The method for the manufacture of stone paper according to embodiment 26, wherein the d95 particle size of the component B) is 90 .m or lower and the mixture of components in step b) is fed to a blow-film device or extrusion device, and step c) comprises rolling and stretching of the composition.

[0265] 28. A method for the manufacture of stone paper according to embodiment 26, wherein the d95 particle size of the component B) is 90 .m or higher and the mixture of components in step b) is fed to a calander device, and step c) extrusion comprises rolling of the composition. 29. A method for the manufacture of stone paper according to any of the embodiments 26 to 28, wherein a coating layer is applied to the product of step c), preferably in a dry or liquid coating process.

[0266] 30. A method for the manufacture of stone paper according to any of the embodiments 26 to 29, wherein a barrier film is applied to the product of step c) or d), preferably in a dry or liquid coating process.

[0267] In the following, the invention is explained further by means of examples, without being limited to these specific examples.

[0268] Examples

[0269] Example 1a): Production of a thermoplastic composition and a stone paper

[0270] In a Hosokawa Alpine AHM 132 mill, 550kg of coated calcium carbonate powder (55 weight- %; 99.10 % CaCC>3 (w / w), 0.8 % MgCCh (w / w), D50: 2.9 m, D98: 10 pm, Mikhart C), 150 kg of tributyl O-acetyl citrate (15 weight-%; Citrofol Bl I (Jungbunzlauer), min 99.0 % pure (GC assay)) and 300 kg polybutylene adipate terephthalate (PBAT) (30 weight-%; ECOPOND® KB100, Zhuhai Kingfa Biomaterial Co., Ltd.) were mixed. 1000 kg of the composition thus obtained were granulated using a Leistritz ZSE 75Maxx extruder.

[0271] Then, the granulated composition was submitted to flat film extrusion using a Leistritz single screw extruder to obtain a flat film having a thickness of 1 mm.

[0272] By cutting the film into sheets having the format 72 cm x 102 cm, stone paper sheets were provided. and a stone

[0273] The film is obtained as described in Example 1a), but is surface-coated using a side-feeder.

[0274] Then, the film is rolled to a thickness of 120 pm.

[0275] The film was rolled up, and later cut to sheets having the format 72 cm x 102 cm, thus providing stone paper sheets. and a stone

[0276] The film is obtained as described in Example 1a), but the film obtained by flat film extrusion has a thickness of 70 pm (1c), 100 pm (1 d), 150 pm (1e), 200 pm (1 f), 250 pm (1g), 300 pm (1 h), 350 pm (1 i), 400 pm (1j), or 450 pm (1 k).

[0277] Example 11): Production of a thermoplastic composition and a stone paper

[0278] In a Hosokawa Alpine AHM 132 mill, 500kg of coated calcium carbonate powder (50 weight- %; 99.10 % CaCC>3 (w / w), 0.8 % MgCCh (w / w), D50: 2.9 pm, D98: 10 pm, Mikhart C), 10 kg of tributyl O-acetyl citrate (1.0 weight-%; Citrofol BII (Jungbunzlauer), min 99.0 % pure (GC assay)) and 490 kg polybutylene adipate terephthalate (PBAT) (49.0 weight-%; ECOPOND® KB100, Zhuhai Kingfa Biomaterial Co., Ltd.) were mixed. 1000 kg of the composition thus obtained were granulated using a Leistritz ZSE 75Maxx extruder.

[0279] Then, the granulated composition was submitted to flat film extrusion using a Leistritz single screw extruder to obtain a flat film having a thickness of 50 pm.

[0280] By cutting the film into sheets having the format 35 cm x 50 cm and 35 cm x 25 cm, stone paper sheets were provided. The stone paper sheets can be applied as food-safe separator sheets in selling slices of sausage and cheese slices.

[0281] Example 1m) and 1 n): Production of a thermoplastic composition and a stone paper

[0282] A film is obtained by flat film extrusion as described in Example 11), but the film obtained by flat film extrusion has a thickness of 40 m (1m) or 70 pm (1n).

[0283] From both films, a stone paper has been prepared by cutting the film into sheets having the format 35 cm x 50 cm and 35 cm x 25 cm.

[0284] Example 1o-q): Production of a thermoplastic compositions and coated printable stone paper

[0285] In a Hosokawa Alpine AHM 132 mill, 650 kg of coated calcium carbonate powder (65 weight- %; 99.10 % CaCC>3 (w / w), 0.8 % MgCCh (w / w), D50: 2.9 pm, D98: 10 pm, Mikhart C), 10 kg of tributyl O-acetyl citrate (1.0 weight-%; Citrofol BII (Jungbunzlauer), min 99.0 % pure (GC assay)) and 340 kg polybutylene adipate terephthalate (PBAT) (34.0 weight-%; ECOPOND® KB100, Zhuhai Kingfa Biomaterial Co., Ltd.) were mixed. 1000 kg of the composition thus obtained were granulated using a Leistritz ZSE 75Maxx extruder.

[0286] Then, the granulated composition was submitted to flat film extrusion using a Leistritz single screw extruder to obtain a flat film having a thickness of 250 pm (Example 1o) ), 300 pm (Example 1p) ), or 350 pm (Example 1q) ).

[0287] Thus obtained extruded flat films were reheated, rolled and given a paper coating (curtain coating process using a calcium carbonate (GCC) dispersion; Omya HYDROCARB 90-ME 78% in a variable Coater of Contiweb, NL), and drawn onto a roll using a SOMATEC winding machine. The rolls were then cut to sheets in the format of 72 x 102cm. The sheets were further cut to sheets having a width 560mm for printing, and were then printed using an offset printing machine (Heidelberger Offset Druckmaschine) or a digital printing machine (HP Indigo).

[0288] In order to produce moisture- and dirt resistant menues with good haptic properties, e.g for restaurants, the printed sheets were cut into 2 or 4 cards.

[0289] Example 2: Production of a notebook comprising the thermoplastic composition of the invention in the form of a stone paper (“stonebook”)

[0290] The sheets obtained in Example 1a) were offset-printed, then cut to DIN A5 size and then mounted on a stone paper cover having a thickness of 2.5 mm, which is obtained by pressing and heating a granulate of the composition described in Example 1 in a plate mold at 245 °C. 128 additional sheets are glued to the book cover. Thus, the stonebook was finished. Example 3: Production of a bag comprising the thermoplastic composition of the invention

[0291] As described in Example 1a), a flat film is produced by extrusion. The flat film is reheated, rolled and given a paper coating (curtain coating process using a calcium carbonate (GCC) dispersion; Omya HYDROCARB 90-ME 78% in a variable Coater of Contiweb, NL) and drawn onto a roll using a SOMATEC winding machine. The roll is then cut to sheets in the format of 72 x 102cm. The sheets are then printed using an offset printing machine (Heidelberger Offset Druckmaschine) or a digital printing machine (HP Indigo).

[0292] After the sheets are dried, the sheets are creased, and the sheets are glued on both sides of a stronger stone paper (thickness 2.5 mm) and formed into the shape of a bag using a paper machine.

[0293] Example 4: Production of a stone paper film

[0294] The composition as obtained in Example 1 is pregranulated, heated and fed to an extruder (Reifenhauser). In the extruder, air is supplied and the material is inflated using the blown film technique to a height of 14.5m, cooled and processed as a roll. After storage, this roll is cut into the dimensions 50 cm x 35 cm, thus providing stone paper sheets, and printed.

Claims

Claims1. A thermoplastic composition comprising the componentsA) 15 to 53 weight-% polybutylene adipate terephthalate (PBAT), preferably 15 to 45 weight -% PBAT, more preferably 22 to 38 weight-% PBAT, still more preferably 26 to 34 weight-% PBAT,B) 42 to 82 weight-% CaCCh powder, preferably 42 to 75 weight-% CaCCh powder, more preferably 42 to 67 weight-% CaCCh powder, still more preferably 48 to 63 weight-% CaCCh powder, most preferably 52 to 57 weight-% CaCCh powder,C) 0.5 to 20 weight-% of one or more citric acid triesters, preferably 5 to 20 weight-%, more preferably 10 to 19 weight-%, still more preferably 11 to 18 weight-%, and most preferably 12 to 17 weight-% of one or more citric acid triesters,D) optionally up to 10 weight-% of auxiliary compounds, preferably up to 5 weight-% of auxiliary compounds, more preferably up to 2 weight-% auxiliary compounds, even more preferably up to 0.5 weight-% auxiliary compounds; most preferably no further auxiliary compounds, wherein the components A) to D) add up to 100 weight-%.

2. The thermoplastic composition according to claim 1 , wherein the composition comprisesA) 15 to 53 weight-% PBAT, preferably 18 to 50 weight-% PBAT,B) 48 to 82 weight-% CaCCh powder, andC) 0.5 to 2.0 weight-% of one or more citric acid triesters, preferably 0.7 to 1.7 weight-% of one or more citric acid triesters, even more preferably 0.8 to 1.5 weight-% of one or more citric acid triesters, andD) up to 5 weight-% of auxiliary compounds, more preferably up to 2 weight-% auxiliary compounds, even more preferably up to 0.5 weight-% auxiliary compounds, wherein the components A) to D) add up to 100 weight-%.

3. The thermoplastic composition according to claim 1 or 2, wherein the composition comprises 50 weight-% or more of CaCCh powder, more preferably 60 weight-% or more CaCCh powder, and most preferably 70 weight-% or more of CaCCh powder.

4. The thermoplastic composition according to any of the claims 1 to 3, wherein the composition comprises 0.5 to 1.5 weight-% of the citric acid triester compound C) when the composition comprises 48 to 60 weight-% of CaCCh, powder, and the composition comprises 1.0 to 2.0 weight-% of the citric acid triester compound C) when the composition comprises 60 weight-% to 82 weight-% of CaCCh powder.

5. The thermoplastic composition according to any of the previous claims 1 to 4, wherein the composition comprisesA) 36.5 to 51.5 weight-% PBAT,B) 48 to 60 weight-% CaCCh powder, andC) 0.5 to 1.5 weight-% of one or more citric acid triesters, preferably 0.6 to 1.4 weight-% of one or more citric acid triesters, even more preferably 0.7 to 1.3 weight-% of one or more citric acid tri esters, andD) up to 2 weight-% auxiliary compounds, preferably up to 0.5 weight-% auxiliary compounds, wherein the components A) to D) add up to 100 weight-%, preferably the components A) to C) add up to 100 weight-%.

6. The thermoplastic composition according to any of the previous claims 1 to 4, wherein the composition comprisesA) 15.0 to 39.0 weight-% PBAT,B) 60 to 82 weight-% CaCCh powder, andC) 1 .0 to 2.0 weight-% of one or more citric acid triesters, preferably 0.6 to 1.4 weight-% of one or more citric acid triesters, even more preferably 0.7 to 1 .3 weight-% of one or more citric acid triesters, andD) up to 2 weight-% auxiliary compounds, preferably up to 0.5 weight-% auxiliary compounds, wherein the components A) to D) add up to 100 weight-%, preferably the components A) to C) add up to 100 weight-%.

7. The thermoplastic composition according to any of the previous claims 1 to 5, wherein the composition consists ofA) 43.8 to 51 .5 weight-% of PBAT,B) 48 to 55 weight-% of CaCCh powder having a particle diameter d95 of 1 to 100 .m, more preferably of 2 to 60 .m,C) 0.5 to 1.2 weight-% of a citric acid triester compound, preferably triethyl citric acid ester, tributyl citric acid ester, acetyl triethyl citric acid ester or acetyl tributyl citric acid ester.

8. The thermoplastic composition according to any of the previous claims 1 to 4 or 6, wherein the composition consists ofA) 18.0 to 34.0 weight-% of PBAT,B) 65 to 80 weight-% of CaCCh powder having a particle diameter d95 of 1 to 100 .m, more preferably of 2 to 60 .m,C) 1.0 to 2.0 weight-% of a citric acid triester compound, preferably triethyl citric acid ester, tributyl citric acid ester, acetyl triethyl citric acid ester or acetyl tributyl citric acid ester.

9. A thermoplastic composition according to claim 1 , comprising the componentsE) 15 to 45 weight -% PBAT, preferably 22 to 38 weight-% PBAT, more preferably 26 to 34 weight-% PBAT,F) 42 to 67 weight-% CaCCh powder, preferably 48 to 63 weight-% CaCCh powder, more preferably 52 to 57 weight-% CaCCh powder,G) 5 to 20 weight-%, preferably 10 to 19 weight-%, more preferably 11 to 18 weight-%, and most preferably 12 to 17 weight-% of one or more citric acid triesters,H) optionally up to 10 weight-% of auxiliary compounds, preferably up to 5 weight-% of auxiliary compounds, more preferably up to 2 weight-% auxiliary compounds, even more preferably up to 0.5 weight-% auxiliary compounds; most preferably no further auxiliary compounds, wherein the components A) to D) add up to 100 weight-%.

10. The thermoplastic composition according to claim 1 or claim 9, wherein the composition comprisesA) 22 to 38 weight-% PBAT,B) 48 to 63 weight-% CaCOs powder, andC) 10 to 19 weight-% of one or more citric acid triesters, preferably 11 to 18 weight-% of one or more citric acid triesters, even more preferably 12 to 17 weight-% of one or more citric acid triesters, andD) up to 5 weight-% of auxiliary compounds, more preferably up to 2 weight-% auxiliary compounds, even more preferably up to 0.5 weight-% auxiliary compounds, wherein the components A) to D) add up to 100 weight-%.

11. The thermoplastic composition according to any of claims 1 to 10, wherein the component C) is selected from trimethyl, triethyl, tripropyl or tributyl citric acid ester, and wherein the hydroxyl group of the citric acid ester is optionally acylated, and wherein preferably the component C) is selected from the group consisting of triethyl citric acid ester and acetyl tributyl citric acid ester, most preferably component C) is acetyl tributyl citric acid ester.

12. The thermoplastic composition according to any of claims 1 to 11 , wherein the component C) is an acylated citric acid ester, preferably an acetylated citric acid ester.

13. The thermoplastic composition according to any of the previous claims 1 to 12, wherein the composition consists of the components A), B) and C).

14. The thermoplastic composition according to any of the previous claims 1 to 12, wherein the composition comprises an auxiliary component D) of 0.1 to 10 weight-%, preferably 0.5 to 8 weight-%, more preferably 1 to 7 weight-%, even more preferably 2 to 6 weight-% of one or more auxiliary compounds, such as colorants, preservatives, binders, anti-oxidants, light stabilizers, antistatic agents and plasticizers, preferably selected from the group consisting of fatty acids, in particular stearic acid, mineral powder, in particular talcum powder, kaolin powder, or pigments.

15. An article comprising the thermoplastic composition according to any of the previous claims 1 to 14, wherein the article is selected from sheets, cards, books, bags, moulded articles, boxes and containers, separator sheets, cream jars, artificial sausage skins or artificial casings for foodstuff, filaments for 3D printing and a granulate.

16. A stone paper comprising at least one sheet structure having a thickness of 25 .m to 2 mm, preferably 50 .m to 1 mm, more preferably 60 .m to 750 .m, most preferably 75 to 400 .m, wherein the sheet structure consists of a thermoplastic composition as defined in any of the previous claims 1-14.

17. The stone paper according to claim 16, further comprising a coating layer on one or both sides of the sheet structure, wherein the coating layer comprises preferably at least one coating powder selected from kaolin powder, chalk powder, talcum powder , calcium carbonate or marble powder, wherein the coating powder preferably has a d95 to d99 particle size of 0.05 |_im to 2 .m, most preferably talcum powder having a d98 particle size of 0.1 .m to 0.4 .m, or a silicone composition, wherein it is further preferred that there is a coating layer on one side of the sheet structure.

18. The stone paper according to claim 16 or claim 17, wherein the sheet thickness is in the range from 60 .m to 350 .m, more preferably 80 .m to 300 .m, most preferably 100 .m to 250 .m.

19. The stone paper according to any of the claims 16 to 18, wherein the sheet structure consists of a composition comprisingA) 22 to 38 weight-% PBAT, more preferably 26 to 34 weight-% PBAT,B) 48 to 63 weight-% CaCCh powder, more preferably 52 to 57 weight-% CaCCh powder,C) 5 to 20 weight-%, preferably 10 to 19 weight-%, more preferably 11 to 18 weight-%, even more preferably 12 to 17 weight-% of one or more citric acid triesters,D) and optionally up to 5 weight-% of auxiliary compounds, more preferably up to 2 weight- % auxiliary compounds, even more preferably up to 0.5 weight-% auxiliary compounds, wherein the components A) to D) add up to 100 weight-%, and wherein the component C) is preferably selected from trimethyl, triethyl, tripropyl or tributyl citric acid ester, and the hydroxyl group of the citric acid is optionally acylated.

20. The stone paper according to any of the claims 16 to 18, wherein the sheet structure consists of a composition comprisingA) 15 to 53 weight-% PBAT, preferably 18 to 50 weight-% PBAT,B) 48 to 82 weight-% CaCCh powder, andC) 0,5 to 2,0 weight-% of one or more citric acid triesters, preferably 0,7 to 1 ,7 weight-% of one or more citric acid triesters, even more preferably 0,8 to 1 ,5 weight-% of one or more citric acid tri esters, andD) up to 5 weight-% of auxiliary compounds, more preferably up to 2 weight-% auxiliary compounds, even more preferably up to 0.5 weight-% auxiliary compounds, wherein the components A) to D) add up to 100 weight-%.

21. The stone paper according to any of the claims 16, 17 or 20, wherein the sheet thickness is in the range of from 25 .m to 100 .m, and the sheet structure of the stone paper consists of a composition comprisingA) 36.5 to 51.5 weight-% PBAT,B) 48 to 60 weight-% CaCCh powder, andC) 0.5 to 1.5 weight-% of one or more citric acid triesters, preferably 0.6 to 1.4 weight-% of one or more citric acid triesters, even more preferably 0.7 to 1 .3 weight-% of one or more citric acid tri esters, andD) up to 2 weight-% auxiliary compounds, preferably up to 0.5 weight-% auxiliary compounds, wherein the components A) to D) add up to 100 weight-%, and preferably the components A) to C) add up to 100 weight-%.

22. The stone paper according to the previous claim 21 , wherein the sheet structure of the stone paper consists of a composition consisting of the componentsA) 36.5 to 51.5 weight-% PBAT,B) 48 to 60 weight-% CaCCh powder, andC) 0.5 to 1.5 weight-% of one or more citric acid triesters23. The stone paper according to any of the claims 16, 17 or 20, wherein the sheet thickness is in the range of from 100 .m to 2 mm, preferably 200 .m to 1 mm, and the sheet structure of the stone paper consists of a composition comprisingA) 15.0 to 39.0 weight-% PBAT,B) 60 to 82 weight-% CaCCh powder, andC) 1.0 to 2.0 weight-% of one or more citric acid triesters, preferably 0.6 to 1.4 weight-% of one or more citric acid triesters, even more preferably 0.7 to 1.3 weight-% of one or more citric acid tri esters, andD) up to 2 weight-% auxiliary compounds, preferably up to 0.5 weight-% auxiliary compounds, wherein the components A) to D) add up to 100 weight-%, and preferably the components A) to C) add up to 100 weight-%.

24. The stone paper according to the previous claim 23, wherein the sheet structure of the stone paper consists of a composition consisting of the componentsA) 15.0 to 39.0 weight-% PBAT,B) 60 to 82 weight-% CaCCh powder, andC) 1.0 to 2.0 weight-% of one or more citric acid triesters.

25. A method for the manufacture of stone paper, comprising the steps of a) mixing the components A), B), C) and D) of the thermoplastic composition according to claims 1 to 14, wherein optionally one or more further steps of mixing, compacting and smoothing may be performed, b) feeding the mixture of the components obtained in step a) to a calander machine, to a blow-film device or to a plate extrusion system through a feed device, c) forming a sheet structure of the composition for the production of stone paper, optionally comprising the steps of rolling and optionally stretching of the composition, wherein optionally one or more of these steps are performed repeatedly, and optionally d) applying a coating layer to one or both sides of the sheet structure obtainedfrom step c) by a liquid coating process or a dry coating process, and further optionally e) applying a barrier film by bathing the product obtained from step c) or step d) in a dry or liquid coating process.

26. The method for the manufacture of stone paper according to claim 25, wherein the d95 particle size of the component B) is 90 .m or lower and the mixture of components in step b) is fed to a blow-film device or extrusion device, and step c) comprises rolling and stretching of the composition, or wherein the d95 particle size of the component B) is 90 .m or higher and the mixture of components in step b) is fed to a calander device, and step c) is extrusion comprising rolling of the composition.

27. A method for the manufacture of stone paper according to any of the claims 25 or 26, wherein a coating layer is applied to the product of step c), preferably in a dry or liquid coating process.

28. A method for the manufacture of stone paper according to any of the claims 25 to 27, wherein a barrier film is applied to the product of step c) or d), preferably in a dry or liquid coating process.

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