Rotomolding product, method of manufacturing an article, article made of product, and use

Abstract

The present invention relates to powdered products, especially for rotomoulding, that contain free flowing particles formed of an impact modified thermoplastic composition comprising: an aliphatic polyamide and a polyolefinic impact modifier comprising at least a maleic acid modified polyolefinic impact modifier. The polyamide has a RV of at most 2.50; the polyolefinic impact modifier has a MFR of at most 15 g / 10 min. The thermoplastic composition comprises at least 22.5 pbw of the polyolefinic impact modifier per 100 parts of the polyamide and the polyolefinic impact modifier. The polyolefinic impact modifier has a maleic anhydride content greater 0.75 wt% - 3 wt%, relative to the combined weight of the polyolefinic impact modifier comprised in the product. The present invention further relates to rotomolded articles, especially hydrogen storage tanks made with the powdered product, a method of manufacturing such articles, and uses of the composition.

Description

[0001] ROTOMOLDING PRODUCT, METHOD OF MANUFACTURING AN ARTICLE, ARTICLE MADE OF PRODUCT, AND USE

[0002] The present invention relates to a powdered product, specifically a product for manufacturing of a rotomolded article, the powdered product containing free flowing particles formed of an impact modified thermoplastic composition. The present invention further relates to: a method of manufacturing a rotomolded article; the rotomolded article, preferably a container for storage of a fluid, such as hydrogen; to a use of the impact modified thermoplastic composition for the manufacturing of a container for storage of a fluid, such as pressurized gas; and to the use of a maleic anhydride modified polyolefin impact modifier to mitigate phase segregation during melt processing, in particular rotomolding, of an impact modified thermoplastic composition.

[0003] BACKGROUND

[0004] Impact modified polyamide compositions are known in the art. Impact modified polyamide compositions and rotational molded articles made thereof are described in, for example, US2021 / 0139699A1. In US2021 / 0139699A1 , two other patent documents are referred to: W02017 / 094720 (with English equivalent US2021 / 0301131A1) and JP2013-532748 (with English equivalent US9309406B2). Both documents describe impact modified polyamide compositions, with US2021 / 0301131A1 being primarily directed to injection molded parts, whereas US9309406B2 is directed to fuel parts which can be made by injection-molding, or blow molding, or rotomolding.

[0005] According to US2021 / 0301131A1 there has been a demand for a polyamide resin composition having excellent moldability (measured by spiral flowability during injection molding) or appearance (surface gloss) as a molded product, which does not impair the intrinsic mechanical strength (impact resistance) exhibited by a polyamide resin as much as possible and is provided with flexibility. US2021 / 0301131A1 mentions that there can be a problem with the flowability of polyamide compositions; and although the flowability can be improved by using a polyamide resin having a low molecular weight or using a fluidity modifier (plasticizers or waxes), these methods in return have different problems, such as reduction of impact strength, and thus have limitations in applications thereof. US2021 / 0301131A1 claims to have solved these problems by using a specific acid-modified modified polyolefin (Q) with a melt flow rate (MFR) at 230 °C under a load of 2.16 kg of 50 to 200 g / 10 min in an amount of 1 to 50 wt.%, in combination with 50 to 99 wt.% of a polyamide. According to US2021 / 0301131A1, by controlling the MFR of the acid-modified polyolefin (Q) within this range, a polyamide resin molded product having an excellent balance between impact resistance and specular glossiness or an excellent balance between impact resistance and fluidity during molding of a molded product is obtained. In the examples of US20210301131A1 , a polyamide 66 with a viscosity number 145-150 cm3 / g, was used for the polyamide (P) and two grades of modified polyolefins Q were tested individually and used in amounts of 10 wt.% or 20 wt.%. However, with 10 wt.%, the values for the elongation at break (23°C) were very low, whereas with the 20 wt.% the melt viscosities were very high, even at a temperature as high as 290 °C, making these materials unsuitable for use in rotational molding. Furthermore, US2021 / 0139699 also discloses that although in US20210301131A1 the liquidity is improved by using a polyolefin having a relatively lower viscosity as the acid modified polyolefin, the impact resistance particularly at low temperature is decreased.

[0006] US9309406B2 (corresponding with J P2013-532748) relates to a fuel part, comprising a polymer composition comprising: a polyamide which has a ratio of terminal carboxy group concentration over terminal amino group concentration of 1 or more, a micro talcum in an amount of 0.001 to 1 wt.% based on the total amount of the polymer composition, and an impact modifier in an amount of at least 1.0 wt.%, based on the total amount of the polymer composition. In the examples, the following components were used: polyamide PA6; micro-talcum (with a median diameter of 0.50 micrometer, 99% was less than 5 micrometer, 92% less than 2 micrometer and 75% less than 1 micrometer); and a maleic anhydride (MAH) grafted ethene copolymer as impact modifier. Examples with 9.75 wt.% and 20 wt.% of impact modifier were reported. The patent document JP2013-532748 was commented in US2021 / 0139699A1, by disclosing that the blend of the impact resistance improving agent and the polyamide resin results in significantly increase of the viscosity of the polyamide resin composition obtained by the chemical reaction between them; and that the rotational molded article obtained by rotational molding of such a polyamide resin composition has poor surface property such that a particulate tends to remain at the surface, which was not suitable for the application for rotational molding.

[0007] US2021 / 0139699A1 describes an impact modified polyamide resin composition for rotational molding and a rotational molded article using the same. The polyamide resin composition of US2021 / 0139699A1 comprises: component (A): an aliphatic polyamide having a relative viscosity (qr) of less than 2.6 (as measured according to JIS K6920 under the conditions of 96 wt.% of sulfuric acid, 1 wt.% of the polymer concentration and 25 °C) in an amount of ‘a’ parts by weight (pbw); component (B): a modified polyolefin having a density of 0.895 g / cm2or less as measured according to ASTM D1505 in an amount of ‘b’ pbw; and component (C): a non-modified polyolefin having an MFR value of 3.0 to 30 g / 10 min as measured in a load of 2.16 kg at 190 °C in an amount of ‘c’ pbw; wherein the polyamide resin composition satisfies the following equations: 50 < c / (b + c) x100 = 70, and 10 < (b + c) / (a + b + c) x100 < 40.

[0008] In other words, the amount of the modified polyolefin (B) is at most half of the combined amount of the modified polyolefin (B) and the non-modified polyolefin (C), and (B) also is at most 20 pbw, relative to the total amount of the polyamide (A) and components (B) and (C).

[0009] In the examples of US2021 / 0139699A1 , a polyamide 6 with a relative viscosity (qr) of 2.20, or with a relative viscosity (qr) of 2.45 was used for component (A), a maleic anhydride-modified ethylene-a-olefin copolymer (TAFMER MH5020, density=0.866) for component (B) (amount 6.8 to 13.0 pbw), and a non-modified polyolefin (EVOLUE SP0540, MFR value=3.8 g / 10 min at 190 °C, 2.16 kg; ISO 1133)) for component (C) (amount 13.2 - 17.2 pbw). In most compositions a semi-aromatic polyamide (8.0 pbw or 15 pbw) was present. The amount of polyamide 6 (component A) was making up for the total of 100 pbw. Among the properties reported are surface quality, Charpy impact strength values at -60 °C and tensile elongation at 23 °C, which show the presence of the non-modified polyolefin to being essential for the results. However, although the surface quality is better for the compositions with the polyamide 6 with a relative viscosity (qr) of 2.20, the mechanical properties of impact strength and tensile elongation are better for the composition with the polyamide 6 having a relative viscosity (qr) of 2.45 in combination with 15 pbw of semi-aromatic polyamide. Furthermore, comparative experiments show that mechanical properties improve with a higher content in non-modified polyolefin, but surface properties are not satisfactory, while the mechanical properties decrease with a lower content in non-modified polyolefin or the absence of the semi-aromatic polyamide.

[0010] US2021261773A1 relates to a composition comprising: a) 30-90 wt % of a polyamide and b) 10-40 wt % of a polyethylene elastomer (POE) composition, wherein the amounts of a) and b) are with respect to the total composition, wherein the total of a) and b) is at least 60 wt % with respect to the total composition, wherein the POE composition consists of: b1) 20-95 wt % of a non-functionalized polyethylene elastomer and b2) 5-80 wt % of a functionalized polyethylene elastomer, wherein the amounts of b1) and b2) are with respect to the POE composition. US2021261773A1 mentions that the composition may be used for rotational molding. JP 2004 346240 A concerns a polyamide resin composition which can give a molded article excellent in rigidity, heat-enduring rigidity, dimensional stability, impact resistance, toughness, flow property and appearance. The composition is described to be suitable as structural or exterior members of electrical / electronic and automobile parts. The thermoplastic polyamide resin composition contains (A) a thermoplastic polyamide resin component, (B) an olefin-based polymer component grafted / modified with an unsaturated dicarboxylic acid, (C) talc component, and (D) a pentaerythritol type phosphite component in specific ratios.

[0011] EP4198089A1 describes a polyamide resin composition described to give molded articles excellent in terms of mechanical strength and impact resistance. The polyamide resin composition comprises 52-88 mass% aliphatic polyamide resin (A), 5- 25 mass% copolyolefin resin (B) having functional groups, up to 20 mass% olefin homopolymer (C) containing no functional group, and 0.05-3.0 mass% both a primary antioxidant (D) and a secondary antioxidant (E), the amount of the polyamide resin composition being taken as 100 mass%, wherein the copolyolefin resin (B) having functional groups has an MFR, as determined at a temperature of 230°C and a load of 2,160 g in accordance with ASTM D1238, greater than 1.0 g / 10 min but less than 5.0 g / 10 min, the polyamide resin composition containing the secondary antioxidant (E) in an amount larger than that of the primary antioxidant (D).

[0012] Apart from the criticality of the flowability of the materials to obtain products with low porosity, evenness in wall thickness and smooth surface, good mechanical properties in tensile tests and a high impact resistance in Charpy impact tests, both at room temperature and at low temperature, the inventors have observed that impact modified polyamide compositions generally exhibit poor or even bad results in impact tests with a falling weight. Falling weight impact test result is an indication for the mechanical performance of the tank produced. A poor falling weight impact result indicates that the tank will not pass the mechanical requirements, usually a drop test at -40 °C from a certain height. This property can be relevant during transport of rotomolded products or in the practical use

[0013] Rotational molding is a known method for manufacturing of molded plastic articles. Rotational molding, also sometimes referred to as rotomolding, involves a heated mold which is filled with a charge of a material, e.g. a thermoplastic material. The mold is rotated (usually around two perpendicular axes), causing the heated and softened material to disperse and stick to the walls of the mold forming a hollow part. The process can be particularly beneficial for manufacturing of large hollow articles, such as fluid storage tanks, e.g. fuel. Disadvantages include long cycle times (e.g. approximately 30 minutes per article), and large heat loads to which the plastic material is exposed to as compared to other molding methods such as injection molding.

[0014] It is an object of the present invention to provide a product that is particularly suitable for manufacturing articles by a rotational molding, preferably a gas storage container, that are based on an impact modified polyamide composition. The product advantageously provides a good flowability and stability against phase segregation. The product can advantageously further provide a good balance between mechanical properties and impact resistance at room temperature and at low temperature and / or exhibit good results in a falling weight impact test. A further object is to provide a rotational molded article having a good balance in surface quality, mechanical properties and impact resistance at room temperature and at low temperature and exhibiting satisfactory results in a falling weight impact test. Advantageously, the product can yield a rotomolded article having good, or at least comparable, resistance to permeation of gases to be stored as compared to articles realized from grades with a similar base polyamide but with production methods involving a lower exposure to heat loads, such as injection molding.

[0015] BRIEF DESCRIPTION OF DRAWINGS

[0016] These and other features, aspects, and advantages of the present disclosure will become better understood from the following description, appended claims, and accompanying drawings wherein:

[0017] FIG 1 represents a schematic cross section size view of a container 1 having a wall structure 2 that bounding an internal storage volume;

[0018] FIGs 2A-D concern a rotomolded container based on a composition comprising 0.5 wt% (weight percent) MAH, whereby FIG 2A is a photo of a top part of the container as indicated in FIG 1 , wherein FIG 2B is an photo of the inside surface of a portion of the container wall; FIG 2C is an optical image of a slice spanning the thickness of the wall; and FIG 2D is a scanning electron micrograph illustrating a portion of a cut across the thickness of the wall,

[0019] FIGs 3A-D concern a rotomolded container based on a composition comprising 1.0 wt% MAH, whereby FIG 3A is a photo of a top part of the container as indicated in FIG 1 , wherein FIG 3B is an photo of the inside surface of a portion of the container wall; FIG 3C is an optical image of a slice spanning the thickness of the wall; and FIG 3D is a scanning electron micrograph illustrating a portion of a cut across the thickness of the wall; FIGs 4A-D concern a rotomolded container based on a composition comprising 2.0 wt% MAH, whereby FIG 4A is a photo of a top part of the container as indicated in FIG 1, wherein FIG 4B is an photo of the inside surface of portion of the container wall; FIG 4G is an optical image of a slice spanning the thickness of the wall; and FIG 4D is a scanning electron micrograph illustrating a portion of a cut across the thickness of the wall.

[0020] The widths of the areas depicted in Figs 2B, 3B, and 4B are respectively about 7; 7.5; and 8 cm.

[0021] DESCRIPTION of EMBODIMENTS

[0022] These objects as described above have been achieved with product containing particles formed of an impact modified thermoplastic composition according to the invention.

[0023] The impact modified thermoplastic composition comprises: a polyamide (PA), and a polyolefinic impact modifier, wherein the polyolefinic impact modifier has a maleic anhydride (MAH) content of at least 0.75 wt% (weight percent) relative to the combined weight of polyolefinic impact modifier comprised in the product (i.e. sum of the weights of polyolefinic impact modifiers contained in the composition).

[0024] Typically, the MAH content does not exceed 4 wt%. Inventors find that modified impact modifiers having an MAH content in excess of 4 wt% become increasingly hard to process. Preferably, the MAH content does not exceed 3 wt%.

[0025] Advantageously the product can be in a form of a free flowing powder.

[0026] The polyamide is preferably comprises an aliphatic polyamide (APA) and / or has a relative viscosity (RV), measured at 0.01 g / ml in 96% sulphoric acid and at 25 °C by the method according to 180307:2019, of at most 2.50. Aromatic polyamides and / or polyamides with RV > 2.50 were found to be less suitable for rotomolding, especially for manufacturing of containers, like hydrogen storage containers with a comparatively large dimension. For reasons outlined hereinbelow the melt flow rate (MFR) of the polyolefinic impact modifier employed, measured at 230 °C and a test load of 2.16 kg by the method according to ISO 1133:2011 , is at most 15 g / 10 min.

[0027] As described hereinbelow in more detail the amount of the polyolefinic impact modifier, modified and the optional non-modified combined, is preferably at least 22.5 parts by weight (pbw) per 100 pbw of the sum of the polyolefinic impact modifier and the polyamide employed. Providing the powdered product in a form of a free-flowing powder has a benefit that the product can spread well and / or evenly during rotational molding.

[0028] Inventors surprisingly found that rendering the product from the composition as described herein reduces or even eliminates phase segregation and / or accumulation of impact modifier, especially at grain boundaries, during or as a result of rotomolding. Without wishing to be bound by theory inventors find the use of MAH in an amount of at least 0.75 wt% contributes to realizing a rotomolded article, wherein the wall structure as formed upon cooling and release from the mold displays minimal or even no observable phase segregation between the polyamide and impact modifier content, including modified impact modifier (MIM), as comprised in the composition within the powdered molding composition, in particular at boundaries between adjacent grains of particles of the powdered product fused during heat provided over the course of the rotomolding process. In contrast, compositions wherein the MAH content was somewhat lower, e.g. 0.5 wt%, were found to exhibit phase segregated fractions as identifiable by electron microscopy. These phase segregated sections were attributed to modified impact modifier accumulation, and non-modified impact modifier if present, at the particle or grain boundaries as a result of prolonged exposure to heat over the course of the rotomolding process. Notably, these accumulated fractions were found to form a continuous network across the thickness of walls of the rotomolded article, thus forming a permeation pathway. In contrast, accumulation at grain boundaries was not observed for articles realized by injection molding, even for composition having only 0.5 wt% of MAH. Inventors believe this discrepancy can be explained by the comparatively higher and / or longer exposures of the composition to heat in rotomolding as compared to injection molding. Without wishing to be bound by theory inventors find that mitigating or eliminating this accumulation improves the ability of the formed rotomolded article to resist permeation of liquids and / or gases, e.g. permanent gases such as N2, O2, and or H2, and / or gaseous hydrocarbons, e.g. CH4, C2H6, C3H8, etc. Further, inventors find that mitigating accumulation of impact modifier at grain boundaries contributes to improving mechanical performance and / or homogeneity of products, especially rotomolded products, based on compositions according to the invention.

[0029] It will be appreciated that use of the powdered product according to the invention is not restricted to rotomolding applications, but that the composition according to the invention can be applied in other thermoforming applications such as injection molding. However, it’s use can be particular beneficial in applications involving heating the composition to a temperature for a period at which for compositions that are comparable, except for the MAH content aspects described herein, display phase segregation.

[0030] Inventors find that mitigating permeation pathways formed by accumulated impact modified renders the permeation performance of formed article to be increasingly close to the permeation performance of the polyamide as used.

[0031] Advantageously, the powdered product as disclosed herein can allow the realization of articles using known rotomolding process, e.g. containers for storing fluid(s), while mitigating or even eliminating phase segregation or formation of a connected network of impact modifier accumulated at grain boundaries or otherwise. For storage applications of pressurized gases a reinforced outer layer, e.g. based on a fiber reinforced composite, may be provided. Applications may include, but are not limited to, hydrogen storage, compressed natural gas (CNG), and pressurized air products. The rotomolded article, which may be referred to as a liner, acts as a barrier layer for containing the fluid. As will become more apparent from the specification hereinbelow the powdered product and rotomolded container based thereon can be of particular advantage in the field of high pressure (e.g. 350-700 bar) hydrogen storage, particularly in mobility applications enabling replacing of comparatively heavier (e.g. steel) solutions.

[0032] The advantages as to mitigating accumulation of impact modifier can be of particular benefit for realization of containers, e.g. containers or liners for the storage containers. It will be appreciated that the application of the powdered product according to the invention is not limited to storage solutions but can be used for a broad range of rotomolded articles benefitting from reduced permeability and / or improved mechanical performance.

[0033] The powdered product is preferably characterized by having a size distribution having a d10, a d50, and / or a d90 that are each within a range from 10 pm to 2000 pm, preferably the d10 and the d50 are within 50-900 pm and the d90 is between 100-1200 pm. Inventors found that the size distribution as listed above constitutes an optimum for realizing good heat transfer and / or even distribution of the powder during rotomolding. Increasing particle size is believed to generally increase flowability of the powder, whereas smaller grains can improve heat transfer at a cost of reduced flowability.

[0034] Preferably, d10 is within 100 pm to 800 pm. Preferably d50 is within 175-800 pm. Preferably d90 is within 275-1100 pm. Inventors found at least acceptable powder flow performance for powders having characteristics within said ranges. More preferably, d10 is between 200-800 pm or even between 200-600; d50 is between 350 and 800 pm or even 350-700 pm, and d90 is between 100 and 1000 pm. Most preferably d10 is between 400 and 800 pm or even 400-600 pm; d50 is between 500 and 800 pm, and / or d90 is between 675 and 1000 pm. The ranges listed above were found to yield increasingly improved performed in terms of powder flow and / or homogeneity of realized wall thickness. Particle size analysis may be performed standard using particle size determination methods, for example by methods as described in ISO 13320:2020 or by imaging, e.g. using scanning electron microcopy, with image analysis, such as Smile view™ map software available from JEOL Ltd. The d 10, d50 and d90 refer to so-called percentile values, which are statistical parameters read the cumulative particle size distribution. They indicate the size below which respectively 10%, 50% or 90% of all particles are found.

[0035] Alternatively, or in addition, the powdered products can be characterized by having a size cut off for particles above a certain upper limit. The upper limit of can be 1000 pm or lower, such as 800 pm. Reducing a content of particles above the threshold mitigates a prevalence of potential point defects.

[0036] The hereinabove described characteristics as to particle size and size distribution can be realized using methods known in the field. Suitable processes included grinding and / or milling, for example cryogenic milling and one or more sieving steps.

[0037] In some variations the MAH content is greater than or equal to 0.75 wt% and less than or equal to 3 wt%, preferably between 0.75 and 2.5 wt%, more preferably between 0.75 and 1.5 wt%. Rotomolded articles based on a powder as disclosed herein having an MAH content between 0.75 and 2.5 wt% were found to have comparatively smoother inner surfaces (i.e. surfaces facing away from the mold wall), which inventors find can be an indicator for reduced surface reactions or degradation, e.g. under thermo-oxidative conditions. Rotomolded articles based on a powder as disclosed herein having an MAH content between 0.75 and 1.5 wt% were further found to found display less coloration (typically brown coloration). Without desired of being bound by theory inventors find coloration (typically browning) can be an indication of partial oxidative degradation (see e.g. D. Fdrsstrdm and B, Terselius, Polymer Degradation and Stability, volume 67 (2000) page 69-78) and / or formation of a crosslinked shell at the surface, which may reduce impact resistance, especially at low temperatures (increased embrittlement).

[0038] Typically, the composition comprises no modified impact modifiers other than MAH modified impact modifiers. It will be appreciated that a target MAH content can be provided by employing a MIM having an appropriate MAH content. Alternatively, an MAH content may be set my mixing / blending impact modifiers having different MAH content, e.g. equal amounts of a 0.5 wt% and unmodified impact modifier to obtain a 0.25 wt% modified IM.

[0039] The powdered product can be characterized by having a low water content. Water content is preferably <1 wt%, more preferably < 0.5 wt% or less, as based on the total weight of the product. Advantageously, the water content can be as low as < 0.2 wt%, e.g. < 0.15w t%. Having a low water content, preferably as low as possible, mitigates generation of vapors and / or side reactions during rotomolding. Drying, if needed, can be applied. Preferred driers are de-humidified driers, preferably with dew points maintained between -30 and -40°C. Vacuum driers with N2 purge can also be used. Hot air ovens or hopper driers are not or at least less suitable for pre-drying; the use of such driers may lower performance. Moisture absorption, e.g. from ambient, can be fully reversible. Preferably drying temperature does not exceed 100 °C.

[0040] According to a further aspect there is provided an impact modified polyamide composition. The composition comprises a polyamide (PA), and polyolefinic impact modifier, wherein the polyolefinic impact modifier has a maleic anhydride (MAH) content of at least 0.75 wt% relative to the combined weight polyolefinic impact modifier comprised in the rotomoulding product (i.e. sum of the weights of polyolefinic impact modifiers contained in the composition).

[0041] The composition as disclosed herein can advantageously be used to form the powdered product according to the invention.

[0042] The PA preferably comprises or consists of, at least predominantly contains, one or more aliphatic polyamides (APA). The relative amounts of PA, impact modifier having an MAH content > 0.75 wt%, and other constituents can depend on the nature type of PA employed, including its relative viscosity, as described herein below. Inventors find that compositions according to the invention can advantageously provide a polyamide composition that is preferably suitable for rotational molding and has a good balance in flowability and mechanical properties. Further, the composition can contribute to rendering a good balance in surface quality, mechanical properties and impact resistance at room temperature and at low temperature, while exhibiting satisfactory results in a falling weight impact test, for a molded articles formed by the composition, including articles made by rotational molding.

[0043] In a preferred variation the impact modified polyamide composition consists of:

[0044] X parts by weight (pbw) of an aliphatic polyamide (APA), and

[0045] Y parts by weight (pbw) of the olefinic impact modifier (with overall MAH content > 0.75 wt%) , and one or more other polymer components and / or one or more additives (together herein referred to as other components Z), which differ from X and differ from Y, and which combinedly add up to an amount of 0 - 30 pbw, as defined relative to 100 pbw of the sum of X and Y); wherein the aliphatic polyamide (APA) has a relative viscosity (RV), measured at 0.01 g / ml in 96% sulphuric acid and at 25 °C by the method according to IS0307:2019, of at most 2.50; the olefinic impact modifier has a melt flow rate (MFR) measured at 230 °C and with a test load of 2.16 kg by the method according to ISO 1133:2011 , of at most 15 g / 10 min; and the sum of X and Y is 100 pbw, and wherein X is at most 77.5 pbw and Y is at least 22.5 pbw, whereby

[0046] -for the relative viscosity (RV) of the aliphatic polyamide (APA) up to and including 2.20, X is at least 60 pbw and Y is at most 40 pbw;

[0047] -for the relative viscosity (RV) of the aliphatic polyamide (APA) in a range of between above 2.20 up to and including 2.33, X is at least 65 pbw and Y is at most 35 pbw; and

[0048] -for the relative viscosity (RV) of the aliphatic polyamide (APA) in a range of between above 2.33 up to and including 2.50, X is at least 70 pbw and Y is at most 30 pbw; and, wherein the other components Z comprise no more than 10 pbw of a non-modified polyolefin and no more than 2 pbw of a micro talcum, relative to the 100 pbw of the combined amount of X and Y, with the provisio that, the one or more other polymer components and the one or more additives (together referred to as other components Z) differ from X and differ from Y, and combinedly add up to an amount in the range of 0 - 30 pbw relative to 100 pbw of the sum of X and Y.

[0049] The effect of the impact modified polyamide composition according to the invention comprising the polyamide and the olefinic impact modifier (with overall MAH content > 0.75 wt%) with the said parameters in the said amounts is not only that the polyamide composition has a good balance in flowability, mechanical properties and impact resistance at room temperature and at low temperature, but also a positive falling weight impact test result at low temperature. A further effect is that the polyamide composition is suitable for rotational molding and that a rotational molded article made thereof not only has a good balance in surface quality, mechanical properties and impact resistance at room temperature and at low temperature, but also shows a tough performance in a falling weight impact test at low temperature.

[0050] As to the restriction of the polyamide composition comprising a restricted amount of others Z it is noted that inventors found that presence of an excess of other constituents can negatively affect one or more of: flowability, mechanical properties, impact resistance at room temperature and at low temperature, falling weight impact properties at low temperature, and / or gas barrier properties of the polyamide composition. Inventors in particular find that one or more of flowability and barrier properties may be progressively negatively affected by excessive addition of nonmodified polyolefin (including non-modified impact modifiers), respectively excessive addition inorganic filler particles, specifically micro talcum.

[0051] These results are very surprising in several aspects, i.e., not only in that a good flowability is obtained with a olefinic impact modifier having a low melt flow rate, even when using said modified polyolefin impact modifier in a relatively large amount, but also that good mechanical properties and impact resistance are obtained with a polyamide having in particular a low relative viscosity (RV), even in the absence, or the presence of a low amount, of a non-modified polyolefin, or a semi-aromatic polyamide, and at the same time also showing positive results in a falling weight impact test.

[0052] It is to be appreciated the combined amount of constituents (Z) other than the aliphatic polyamide (APA) and the olefinic impact modifier having a MAH content > 0.75 wt% preferably does not exceed 30 pbw relative 100 pbw of APA and impact modifier (combined), whereby the amount of non-modified polyolefin(s) is no more than 10 pbw, and / or the amount of micro talcum does not exceed 2 pbw.

[0053] Accordingly, in a preferred embodiment of the composition an amount of constituents other than the APA and the olefinic impact modifier adds up to no more than 30 parts by weight (pbw) relative to 100 parts by weight of the APA and the MIM combined, wherein a non-modified polyolefin content adds up to no more than 10 parts by weight (pbw) relative to 100 parts by weight of the APA and the olefinic impact modifier with overall MAH content combined, and the amount of micro talcum does not exceed 2 pbw.

[0054] Inventors find that restricting the amount of tolerable constituents other than APA and MIM contributes to optimizing flowability of the composition during rotomolding.

[0055] The aliphatic polyamide in the composition according to the invention is a polyamide obtainable by polymerizing a lactam, or an aminocarboxylic acid, or an aliphatic diamine and an aliphatic dicarboxylic acid, as raw materials, or copolymerizing any combination thereof, via known methods such as melt polymerization, solution polymerization, or solid phase polymerization. The aliphatic polyamide can be either an AB type polyamide, obtainable by polymerizing a lactam and / or an aminocarboxylic acid; or an AABB type polyamide, obtainable by copolymerizing an aliphatic diamine and an aliphatic dicarboxylic acid; or an AB / AABB type polyamide, being a polyamide copolymer obtainable by copolymerizing a lactam and / or an aminocarboxylic acid in combination with an aliphatic diamine and an aliphatic dicarboxylic acid.

[0056] Examples of lactam include caprolactam, enantolactam, undecanelactam, dodecanelactam, a-pyrrolidone, and a-piperidone. Examples of the aminocarboxylic acid include 6-aminocaproic acid, 7-aminoheptanoic acid, 9-aminononanoic acid, 11- aminoundecanoic acid, and 12-aminododecanoic acid. In the AB type polyamide or AB / AABB copolymer, one kind of lactam or two or more kinds of lactam may be used.

[0057] In the AA / BB type polyamide or AB / AABB copolymer, one kind of aliphatic diamine or two or more kinds of them may be used. The aliphatic diamine suitably is a C2-C20 diamine, i.e., a diamine comprising 2 to 20 carbon atoms, preferably a C4-C12 diamine. The aliphatic diamine can be a linear aliphatic diamine, a branched aliphatic diamine, or a cyclic diamine, or any combination thereof. Examples of linear aliphatic diamine with 2 to 20 carbon atoms are 1,2 ethanediamine, 1,3-propanediamine, 1,4- butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8- octanediamine, 1,9-nonanediamine, 1 ,10-decanediamine, 1 ,11-undecanediamine, 1 ,12-dodecanediamine, 1 ,13-tridecanediamine, 1 ,14-tetradecanediamine, 1 ,15- pentadecanediamine, 1 ,16-hexadecanediamine, 1,17 heptadecanediamine, 1 ,18- octadecanediamine, 1 ,19-nonadecanediamine, 1 ,20-eicosanediamine. The branched aliphatic diamine suitably is a diamine with a methyl substituted aliphatic chain. Examples of branched aliphatic diamine with 4 to 12 carbon atoms are 2-methyl-1,5- pentanediamine, 3-methyl-1,5-pentanediamine, 2-methyl-1,8-octanediamine, 2,2,4- trimethyl-1 ,6-hexanediamine, 2,4,4 trimethyl-1,6-hexanediamine, and 5-methyl-1 ,9- nonanediamine.

[0058] Examples of the aliphatic dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecane diacid, dodecane diacid, tridecane diacid, tetradecane diacid, pentadecane diacid, hexadecane diacid, octadecane diacid, and eicosane diacid. In the AA / BB type polyamide or AB / AABB copolymer, one kind of aliphatic dicarboxylic acid or two or more kinds of them may be used. Examples of AB-type polyamides are the homopolymers polycaprolactam (polyamide 6), polyundecaneamide (polyamide 11), polydodecaneamide (polyamide 12); and any copolymers thereof. Examples of AA / BB type polyamide are polytetramethylene sebacamide (polyamide 410), polyhexamethylene adipamide (polyamide 66), polyhexamethylene suberamide (polyamide 68), polyhexamethylene azelamide (polyamide 69), polyhexamethylene sebacamide (polyamide 610), polyhexamethylene dodecamide (polyamide 612). Examples of copolymer of the AB / AABB type polyamide are polyamide 6 / 66, polyamide 6 / 410, polyamide 6 / 68, polyamide 6 / 610, and polyamide 6 / 6 / 12.

[0059] Preferably the aliphatic polyamide (APA) is an AB polymer. Compared to AABB type polymers AB type polyamide inventors find a reduced propensity to crosslinking and / or cycle formation, e.g. upon reaction with the MAH, which is believed to positively contribute to flowability under rotomolding compositions.

[0060] The aliphatic polyamide (APA) may comprise monomeric components others than those based on lactam, aminocarboxylic acid, aliphatic diamine, and aliphatic dicarboxylic acid; and referred to herein as other or additional monomeric components. Examples of other monomeric components include monoamine, triamine, and polyamine, monocarboxylic acid, dicarboxylic acid, and tricarboxylic acid. These other monomeric components may be either aliphatic monomeric components or aromatic monomeric components. The other monomeric components may also comprise other aromatic monomeric components such as aromatic diamine and aromatic dicarboxylic acid. The aliphatic polyamide in the composition according to the invention suitably comprises other monomeric components in an amount of at most 10 mole%. Herein the aliphatic polyamide may comprise up to and including 5 mole% of an aromatic monomeric component, while still being considered an aliphatic polyamide. For example, the aliphatic polyamide may comprise 3 mole% of an aromatic monomeric component, in combination with at most 7 mole% of other aliphatic monomeric components, or 5 mole% of an aromatic monomeric component, in combination with at most 5 mole% of other aliphatic monomeric components. Preferably, the aliphatic polyamide comprises 0 - 5 mole%, more preferably 0 - 2 mole% of another monomeric component. Herein the other monomeric component can be one other monomeric component, or two or more other monomeric components. Herein the mole percentage (mole%) is relative to the total molar amount of lactam or carboxylic acid, aliphatic diamine, aliphatic dicarboxylic acid, and other monomeric components copolymerized in the aliphatic polymer. Examples of other monomeric components that can be copolymerized into the aliphatic polyamide are known in the art. Among the aliphatic polyamides, that may be used in the composition according to the present invention, the following are preferred: polyamide 6, polyamide 11 , and polyamide 12; and polyamide-6 copolymer obtainable by copolymerization of caprolactam or 6-aminocaproic acid, or a combination thereof, with aliphatic comonomers selected from another lactam and / or aminocarboxylic acid, or an aliphatic diamine and an aliphatic dicarboxylic acid, or another lactam and / or aminocarboxylic acid, and an aliphatic diamine and an aliphatic dicarboxylic acid.

[0061] These polyamides are preferred for their heat stability during molding and for the molding processability. More preferably, the polyamide is a polyamide 6 polymer, being a polyamide 6 homopolymer; or a polyamide 6 copolymer comprising at most 25 mole% of aliphatic comonomer. Even more preferred, the polyamide-6 polymer comprises 0 - 10 mole%, and even more preferred 0 - 5 mole%, and most preferred 0 - 2 mole% of aliphatic comonomer. PA-6 based APA can be preferred for specific applications, such as gas storage tanks. Herein the mole percentage (mole%) is relative to the total amount of caprolactam or 6-aminocaproic acid and aliphatic comonomer copolymerized in the aliphatic polymer.

[0062] The aliphatic polyamide in the composition according to the present invention suitably is a semi-crystalline polyamide. The semi-crystalline polyamide may have a melting temperature (Tm) varying over a wide range. Suitably, the melting temperature Tmis as high as 280 °C or higher, or as low as 160 °C, or lower. Herein Tmis measured by the method according to ISO 11357-3:2018, with a heating ramp of 10 °C / min. Preferably, Tmis in the range of 180 - 260 °C, more preferably in the range of 190 - 240 °C. The advantage thereof is that the composition has a more balanced combination of properties in terms of molding processability, heat stability during molding and mechanical properties for the molded parts.

[0063] Herein, a range is understood to also include the lower and the upper limit. Thus, for instance, in the expression ‘in the range of 180 - 260 °C’, the range includes the lower limit of 180 °C, as well as the upper limit of 260 °C.

[0064] The aliphatic polyamide may be a mixture of two or more polyamides. Herein the polyamides may have a different relative viscosity (RV). In this case, the relative viscosity (RV) of the aliphatic polyamide in the composition according to the invention is the relative viscosity measured for the mixture of the two or more polyamides, at a concentration of 0.01 g of the mixture of the two or more polyamides in 1 ml in 96% sulphuric acid and at 25 °C by the method according to IS0307:2019. For the composition of the present invention, it is essential that the relative viscosity (RV) of the aliphatic polyamide is at most 2.50, not only to achieve good flowability, but also making it possible to use the modified polyolefin impact modifier (MIM) in a sufficiently high amount to obtain the effects of the present invention. For RV in excess of 2.50 inventors find the composition progressively less capable of simultaneously realizing appropriate qualities for rotomolding in combination with an appropriate amount of MIM. Below the 2.50, the relative viscosity (RV) may vary over a wide range. Suitably, the relative viscosity (RV) is as low as 1.90, or even lower, for example 1.80. Preferably, the relative viscosity (RV) is at least 1.90, more preferably at least 2.00. For example, the RV can be in a range of 1.80 - 2.50, preferably 1.90 - 2.50, more preferably 2.00 - 2.50 or 2.00 - 2.40. This has the advantage that the mechanical properties are better retained at a high level including good Charpy impact resistance and acceptable falling weight impact resistance. Also preferably, the viscosity is at most 2.35, more preferably at most 2.30 and even more preferably at most 2.25. This has the advantage that the flowability is improved while mechanical properties are retained at a prominent level including good Charpy impact resistance and acceptable falling weight impact resistance.

[0065] The olefinic impact modifier (MAH content > 0.75 wt%) in the composition according to the present invention has a melt flow rate (MFR) measured at 230 °C and with a test load of 2.16 kg by the method according to ISO 1133:2011 , of at most 15 g / 10 min. The MFR may vary over a broader range, and may be as low as, for example, 0.25 g / 10 min. At too low MFR values, the flowability of the composition is hampered too much for practical use thereof, for example in rotational molding. At too high MFR values for the olefinic impact modifier (MAH content > 0.75 wt%), the mechanical properties are not good, in particular with the polyamide having the relative viscosity (RV) according to the present invention.

[0066] Preferably, the MFR of olefinic impact modifier (MAH content > 0.75 wt%)is at least 0.5 g / 10 min, more preferably at least 0.6 g / 10 min, even more preferably at least 0.8 g / 10 min. Also preferably, the MFR of the olefinic impact modifier (MAH content > 0.75 wt%) is at most 10.0 g / 10 min, more preferably at most 7.0 g / 10 min, even more preferably at most 5.0 g / 10 min. Most preferred, the MFR of the olefinic impact modifier (MAH content > 0.75 wt%) is in the range of 0.5 - 10 g / 10 min, or in the range of 0.8 - 5 g / 10 min, or in the range of 1.0 - 3 g / 10 min.

[0067] With a modified polyolefin impact modifier is herein understood a polymer comprising a polyolefin backbone modified with functional groups. The polyolefin backbone is suitably a copolymer of different olefinic monomers, in particular a-olefinic monomers with 2 - 20 carbon atoms. Example of such a-olefinic monomers include ethylene, propylene, 1 -butene (butylene), isobutylene, 1 -pentene, 1 -hexene, 1- heptene, 1 -octene, 1 -decene, 1 -dodecene, 1 -hexadecene, 1 -octadecene, and 4- methyl-1 -pentene. The polyolefin backbone preferably is a copolymer of two olefins selected from ethylene, propylene, and butylene; or a copolymer of ethylene, propylene, and butylene; or a copolymer of at least one olefin selected from ethylene, propylene and butylene, and at least one other a-olefinic monomer with 4 - 20 carbon atoms. Herein, ethylene-a-olefin copolymers and propylene-a-olefin copolymers are preferred. Herein ethylene in the ethylene-a-olefin copolymers, respectively propylene in the propylene-a-olefin copolymers, is suitably present in an amount of at least 20 mole%, more preferably at least 40 mole%. Among these ethylene-a-olefin copolymers are more preferred, and ethylene-butylene copolymers and ethylene- 1 -octene copolymers, are even more preferred. Alternatively, the backbone can be a homopolymer of a-olefinic monomers.

[0068] The polyolefin backbone may further comprise monomeric units derived from unsaturated monomers other than olefinic monomers. These other unsaturated monomer, or other unsaturated monomers can be, for example, a diene monomer or an aromatic monomer, or a combination thereof. Examples of the diene monomers (for instance, contained in the ethylene-a-olefin copolymer, or in the propylene-a-olefin copolymer) include unconjugated diene components such as 1,4-hexadiene, dicyclopentadiene, 5-ethylidene-2-norbornene, and 2,5-norbornadiene; and conjugated diene components such as butadiene, isoprene and piperylene. Examples of the aromatic monomers (for instance, that may be contained in the ethylene-a-olefin copolymer or the propylene-a-olefin copolymer) include styrene. The other unsaturated monomer can be present, if at all, in an amount of at most 20 mole%, preferably at most 10 mole%, and more preferred in an amount of 0 - 5 mole%. Herein the mole% is relative to the total molar amount of olefinic monomer and other unsaturated monomer in the polyolefin backbone. Polyolefins comprising other unsaturated monomer copolymerized in combination with olefinic monomer, and modified polyolefin impact modifier comprising a polyolefin backbone comprising other copolymerized unsaturated monomer are known in the art.

[0069] The modified polyolefin impact modifier comprises a polyolefin backbone modified with functional groups. Examples of known functional groups include acid groups, epoxy groups and glycidyl groups. The modified polyolefin impact modifier used in the present invention is preferably an acid anhydride-modified polyolefin, preferably maleic acid anhydride. The MAH modified polyolefin can be obtained by modifying a polyolefin with an acid anhydride of an unsaturated carboxylic acid. Examples of the unsaturated anhydride of carboxylic, maleic anhydride, itaconic anhydride, and cis-4-cyclohexen-1 ,2 dicarboxylic acid anhydride. Among these, maleic anhydride or itaconic anhydride is preferred, and maleic anhydride is more preferred.

[0070] Conversely, with a non-modified polyolefin impact modifier is herein understood a polymer comprising a polyolefinic backbone modified without functional groups. The polyolefin backbone can suitably be a copolymer of different olefinic monomers, in particular a-olefinic monomers with 2 - 20 carbon atoms. Examples of such a-olefinic monomers include ethylene, propylene, 1 -butene (butylene), isobutylene, 1 -pentene, 1- hexene, 1 -heptene, 1 -octene, 1 -decene, 1 -dodecene, 1 -hexadecene, 1 -octadecene, and 4-methyl-1 -pentene. The polyolefin backbone preferably is a copolymer of two olefins selected from ethylene, propylene, and butylene; or a copolymer of ethylene, propylene, and butylene; or a copolymer of at least one olefin selected from ethylene, propylene and butylene, and at least one other a-olefinic monomer with 4 - 20 carbon atoms. The polyolefin backbone can suitably be a homopolymer of the olefinic monomers listed above.

[0071] The amount of the modifying functional groups in the modified polyolefin impact modifier may vary as discussed herein. The amount of the functional groups can be expressed as functional modification amount, expressed in weight percentage (wt.%), relative to the weight of the modified polyolefin impact modifier (MIM) or combined weight of olefinic of modified polyolefin impact modifiers, as appropriate.

[0072] Suitably, the modified polyolefin impact modifier (MIM) has a glass transition temperature (Tg) of below 0 °C, and may be as low as -70°C, and even lower. Preferably, the modified polyolefin impact modifier (MIM) has a Tgof at most -40°C, more particular in the range of -40 °C - -70 °C, more preferably at most -50 °C, more preferably at most -55 °C, and most preferably at most -60 °C. Herein Tgis measured by the method according to ISO 11357-2:2020, with a heating ramp of 10 °C / min.

[0073] The modified polyolefin impact modifier (MIM) preferably has a glass transition temperature (Tg) of -50 °C or below, and may be as low as -70°C, and even lower. More preferably, the modified polyolefin impact modifier (MIM) has a Tgof at most - 55°C, even more preferably at most -60 °C. Herein Tgis measured by the method according to ISO 11357-2:2020, with a heating ramp of 10 °C / min. A low Tgis preferred from the viewpoint of mechanical properties at low temperature.

[0074] Preferably, the modified polyolefin impact modifier (MIM) has a density of below 1 g / cm3The density may be as low as 0.80 g / cm3, or even lower, but suitably the density is 0.80 g / cm3or above, for example at least 0.84 g / cm3. More preferably, the modified polyolefin impact modifier (MIM) has a density of at most 0.95 g / cm3, even more preferably at most 0.90 g / cm3, more particularly in the range of 0.80 - 0.90 g / cm3, and most preferably at most 0.88 g / cm3. The density more particularly is in the range of 0.84 - 0.88 g / cm3. Herein the density is measured by the method according to ASTM D1505-03. A low density is preferred from the viewpoint of mechanical properties at low temperature.

[0075] Preferably, the modified polyolefin impact modifier (MIM) has a Shore A hardness of below 100. The Shore A hardness may be as low as 40, or even lower, but suitably is above 45 or above, for example at least 50. More preferably, the modified polyolefin impact modifier (MIM) has a Shore A hardness of at most 90, even more preferably of at most 80, more particularly in the range of 45 -80, and most preferably of at most 75. The Shore A hardness more particularly is in the range of 50 - 75. Herein the Shore A hardness is measured by the method according to ASTM D2240- 15. A low Shore A hardness is preferred from the viewpoint of mechanical properties at low temperature.

[0076] The olefinic impact modifier having an MAH content > 0.75 wt% can be present in the composition according to the invention in an amount of at least 22.5 pbw, and in a range depending on the relative viscosity of the aliphatic polyamide.

[0077] For the relative viscosity (RV) of the aliphatic polyamide (APA) up to and including 2.20, X is at least 60 pbw and Y is at most 40 pbw. For the relative viscosity (RV) of the aliphatic polyamide (APA) in said range, preferably X is in the range of 62.5 -75 pbw and Y is in the range of 25 - 37.5 pbw.

[0078] For the relative viscosity (RV) of the aliphatic polyamide (APA) in a range of higher than 2.20 and at most 2.33, X is at least 65 pbw and Y is at most 35 pbw. Preferably, for the relative viscosity (RV) of the aliphatic polyamide (APA) in a range of higher than 2.20 and at most 2.27, X is in the range of 65 -75 pbw and Y is in the range of 25 - 35 pbw; whereas for the relative viscosity (RV) of the aliphatic polyamide (APA) in a range of higher than 2.27 and at most 2.33, preferably X is at least 69 and Y is at most 31 pbw.

[0079] For the relative viscosity (RV) of the aliphatic polyamide (APA) in a range of higher than 2.33 and at most 2.50, X is at least 70 pbw and Y is at most 30 pbw. Preferably, for the relative viscosity (RV) of the aliphatic polyamide (APA) in said range, X is at least 72.5 pbw and Y is at most 27.5 pbw.

[0080] The advantage of the amount of the olefinic impact modifier having an MAH content > 0.75 wt% in the above preferred ranges in combination with the said ranges for the relative viscosity (RV) of the aliphatic polyamide (APA), is that the composition has an improved balance in properties, in particular in terms of flowability and mechanical properties.

[0081] Preferably, the impact modified polyamide composition has a combination of properties complying with all of the following parameters: a complex viscosity (Eta*) at 250 °C of at most 700 Pa s; an elongation at break at -40 °C of at least 17.5%; a notched impact strength at 23 °C of at least 70 KJ / m2; and a falling weight impact resistance at -40 °C with a success rate of at least 60%.

[0082] Herein the various properties are measured by the following methods: the complex viscosity (Eta*) is measured with dynamic mechanical spectroscopy (DMS) by the method according to ISO 6721-10, with loading time of 5 min, at an angular frequency of 0.1 rad / s. the elongation at break is measured by the method according to ISO 527- 2:2012 Type 1A at a drawing rate of 50 mm / min; the notched impact strength is measured by the method according to ISO 179- 2:2020; and the falling weight impact resistance is measured on 5 injection molded plaques of 80*80*2 mm by the method according to ISO 6603-2-2000-10, and the success rate is determined as the percentage of the plaques that passed the test.

[0083] The value for the complex viscosity (Eta*) of the composition can be, for example, about 550 Pa s, about 425 Pa s, about 300 Pa s, or about 250 Pa s. Suitably, the complex viscosity (Eta*) is at least 200 Pa s.

[0084] More preferably, the impact modified polyamide composition has a complex viscosity (Eta*) at 250 °C of at most 600 Pa s; more preferably at most 500 Pa s. The advantage of a lower complex viscosity is that processing of the composition runs smoother and, in the processing, a less high a molding temperature is needed to obtain high quality products.

[0085] Also more preferably, the impact modified polyamide composition has a combination of properties complying with one or more of the following parameters: an elongation at break at -40 °C of at least 20%; and / or a notched impact strength at 23 °C of at least 75 KJ / m2, most preferably at least 80 KJ / m2.

[0086] The value for the complex elongation-at-break at -40 °C of the composition can be, for example, about 20 %, about 25 %, about 36 %, about 43 % or about 48 %. Suitably, the elongation-at-break at -40 °C is at most 60 %, or even at most 50 %, while still obtaining good to very good results.

[0087] The notched impact strength at 23 °C can be, for example, about 83 KJ / m2, or about 88 KJ / m2, or about 97 KJ / m2, Whereas the notched impact strength may be higher than, for example, 110 KJ / m2, it suitably is at most 110 KJ / m2, more particular at most 105 KJ / m2.

[0088] More preferably, the impact modified polyamide composition has a falling weight impact resistance at -40 °C with a success rate of at least 80 %. The success rate can be as high as 100%, with all tested plaques passing the test successfully.

[0089] The impact modified polyamide composition according to the invention, may also comprise, in addition to the aliphatic polyamide and the MIM, one or more other polymer components and / or one or more additives, which constitute part of other components. These other components can be present, as desired, in an amount within a range not impairing the purpose of the present invention. The additive(s) and / or the other polymer component(s), may suitably be present in an amount in the range of 0.001 - 30 pbw, preferably in the range 0.01 - 20 pbw and more preferable in the range 0.1 - 10 pbw. Herein the parts by weight (pbw) are relative to the 100 pbw for the combined amount X and Y, wherein X represents the amount of the aliphatic polyamide in pbw, and wherein Y represents the amount of the olefinic impact modifier having an MAH content > 0.75 wt%in pbw. Inventors found that addition of other components (others Z) in an amount in excess 30 pbw (relative to the sum of X and Y) can negatively affect one or more of the properties of the composition.

[0090] The other polymer component can be any polymer component or a mixture of polymer components typically used in non-reinforced impact modified polyamide compositions, as long as it does not impair the purpose of the present invention. Suitable examples of other polymer components are semi-aromatic polyamides, other thermoplastic polymers, non-modified polyolefins, and rubbers.

[0091] The non-modified polyolefin in the other polymer component can be, for example, a polyolefin homopolymer or a polyolefin copolymer. Examples of polyolefin homopolymers are polyethylene and polypropylene. Examples of polyolefin copolymers are the unmodified polyolefin copolymers used for the backbones in the MIM. Preferably, the non-modified polyolefin is selected from polyethylene, polypropylene, ethylene-a-olefin copolymer, and propylene-a-olefin copolymer., The non-modified polyolefin can be present in an amount of at most 10 pbw, more preferable at most 7.5 pbw, and at least 1 pbw. Even more preferably, the amount of non-modified polyolefin is in the range of 0 - 5 pbw, relative to the 100 pbw for the combined amount X and Y. The semi-aromatic polyamide in the other polymer component can be a copolymer of an aromatic dicarboxylic acid and an aliphatic diamine; or a copolymer of an aliphatic dicarboxylic acid, an aromatic dicarboxylic acid, and an aliphatic diamine; or a copolymer of an aliphatic dicarboxylic acid, an aromatic diamine and an aliphatic diamine; or a copolymer of an aliphatic dicarboxylic acid and an aromatic diamine; or a copolymer of an aliphatic dicarboxylic acid, an aromatic dicarboxylic acid, an aromatic diamine, and an aliphatic diamine. The semi-aromatic polyamide can be a semicrystalline semi-aromatic polyamide or an amorphous semi-aromatic polyamide. Preferably, the semi-crystalline semi-aromatic polyamide has a melting temperature (Tm), measured by the method mentioned herein, of at most 260 °C, more preferably at most 240 °C, and suitably at least 190 °C. Even more preferably, the semi-aromatic polyamide is an amorphous semi-aromatic polyamide.

[0092] The semi-aromatic polyamide in the other polymer component may comprise aliphatic diamine units having 6-12 carbon atoms, derived from a diamine, or a combination of diamines, selected from the group consisting of 1 ,6-hexanediamine, 1 ,7-heptanediamine, 1 ,8-octanediamine, 1 ,9-nonanediamine, 1 ,10-decanediamine, 1 ,11-undecanediamine, and 1 ,12-dodecanediamine. Next to the aliphatic diamine, the semi-aromatic polyamide may comprise aromatic dicarboxylic acid units derived from dicarboxylic acids selected from the group consisting of terephthalic acid, isophthalic acid and naphthalenedicarboxylic acid.

[0093] The semi-aromatic polyamide can be, in particular, a 6T copolymer, i.e. , a copolymer comprising 6T units next to units from other monomers. Specific examples of the semi-aromatic polyamide suitable for use in the composition according to the invention include poly(hexamethylene terephthalamide / hexamethylene isophthalamide) copolymer (polyamide 6T / 6I), poly(hexamethylene terephthalamide / hexamethylene adipamide) copolymer (polyamide 6T / 66), poly(hexamethylene terephthalamide / hexamethylene sebacamide) copolymer (polyamide 6T / 610), poly(hexamethylene terephthalamide / hexamethylene dodecamide) copolymer (polyamide 6T / 612), poly(hexamethylene terephthalamide / hexamethylene isophthalamide / hexamethylene adipamide) copolymer (polyamide 6T / 6I / 66), poly(hexamethylene terephthalamide / 2-methyl pentamethylene terephthalamide) copolymer (polyamide 6T / M5T), poly(hexamethylene terephthalamide / caproamide) copolymer (polyamide 6T / 6). More preferred examples include poly(hexamethylene isophthalamide / hexamethylene terephthalamide) copolymer (polyamide 6I / 6T), poly(hexamethylene isophthalamide / hexamethylene terephthalamide / hexamethylene adipamide) copolymer (polyamide 6I / 6T / 66), and mixtures thereof. Preferably, the semi-aromatic polyamide in the other polymer component is present in an amount of at most 10 pbw, more preferably at most 7.5 pbw, even more preferably at most 5.0 pbw. Most preferably, the amount of semi-aromatic polyamide is in the range of 0 - 2.5 pbw, relative to the 100 pbw for the combined amount X and Y.

[0094] The additive that may be further present in the impact modified polyamide composition according to the invention can be any additive, or a mixtures of additives, selected from auxiliary additives typically used in non-reinforced impact modified polyamide compositions. Without limiting to the following, the additive can be selected from the group of stabilizers (including heat stabilizers, UV absorbers, light stabilizers, and antioxidants), anti-static agents, lubricants, anti-blocking agents, fillers, crystal nucleating agents, mold release agents, plasticizers, crosslinking agents, foaming agents, colorants (pigments, dyes).

[0095] Preferably, the additive is in an amount of at most 10 pbw, more preferably at most 7.5 pbw. Although the amount may be 0 pbw, even more preferably, the amount of additive is in the range of 0.1 - 5 pbw, relative to the 100 pbw for the combined amount of X of and Y.

[0096] Inventors find that, a higher relative content of other constituents (Z) can negatively affect one or more of flow behavior, and mechanical properties of a rotomolded part, e.g. impact resistance, especially at low temperatures.

[0097] Preferably, the impact modified polyamide composition comprises at least one stabilizer. The advantage thereof is that in case of presence of oxygen during processing, the quality of the molded product is better retained. The stabilizer can be an organic stabilizer, or an inorganic stabilizer, or a combination thereof.

[0098] Examples of organic stabilizers include antioxidants, such as phenol-based antioxidants, thioether-based antioxidants, and / or phosphorus-based antioxidants. The organic stabilizer is preferably at least one selected from the group consisting of phenol-based antioxidants and phosphorus-based antioxidants, and more preferably is at least one selected from the group consisting of hindered phenol-based antioxidants having a t-butyl group at the ortho position, and phosphite ester-based antioxidants of a phenol having a t-butyl group at the ortho position. Suitably, the organic stabilizer is present in an amount in the range of 0.1 - 2 pbw, more particular 0.3 - 1.5 pbw and preferably 0.5 - 1.2 pbw, relative to the 100 pbw for the combined amount of X and Y.

[0099] Examples of inorganic stabilizers include metal halides, for example a copper halide. A particular example of such an inorganic stabilizer is a mixture of cuprous iodide with potassium bromide (Cul / KBr). Preferably, the impact modified polyamide composition comprises at least an inorganic stabilizer, that is more preferably a copper halide. Even more preferably, the composition comprises the copper halide stabilizer in an amount of at least 50 ppm, preferably at least 100 ppm of Cu, relative to the total weight of the impact modified polyamide composition.

[0100] More preferably, the impact modified polyamide composition comprises an organic stabilizer in an amount of at least 0.5 pbw and a copper based inorganic stabilizer in an amount of at least 50 ppm, preferably of at least 100 ppm of Cu. Herein, the parts by weight (pbw) are relative to 100 pbw for the combined amount of aliphatic polyamide (X) and modified polyolefin impact modifier MIM (Y). Herein, the parts per million (ppm) are relative to the total weight of the impact modified polyamide composition.

[0101] Most preferably, a combination of a hindered phenol-based antioxidant having a t-butyl group at the ortho position and a copper based inorganic stabilizer, more particular a combination of a hindered phenol-based antioxidant having a t-butyl group at the ortho position and Cul / KBr is used.

[0102] The additive in the impact modified polyamide composition may comprise a filler. An example thereof is talcum, which is a hydrated magnesium silicate, or microtalcum. Preferably, the composition comprises a micro-talcum. The micro-talcum may be any known micro-talcum suitable for use in polyamide compositions. The micro talcum preferably has a median diameter (d50) of less than 1 micrometer, more preferably less than 70 micrometer, even more preferred less than 50 micrometer. The particle size distribution of micro-talcum is determined by a high-speed image analyzer. This analyzer projects all particles in a limited sample into 2-dimensional images and measures the actual surface area of all captured separate particles. These surface areas are subsequently recalculated into circles having the same surface area of which the diameter is calculated. The median value (d50) of the particle size distribution is then determined by known means.

[0103] The micro-talcum may be present in the polymer composition in an amount up to 10 pbw, e.g. in an amount of 0.001 pbw up to 0 pbw. Preferably, the micro-talcum may be present in the impact modified polyamide composition in an amount in a range of 0.01 - 5.0, more preferably in a range of 0.01 - 3.0 pbw, even more preferably in a range of 0.01 - 2.0 pbw, most preferably from 0.01 to 0.5 pbw. For example, in an embodiment the amount of micro talcum can preferably be 0.05 wt% with respect to a total mass of the composition. Inventors find amounts in a range of at least 0.001 up to about 3 pbw, preferably up to about 2 pbw, most preferably up to 1 pbw, progressively beneficial in providing good impact resistance at low temperature. Excessive amounts of talcum, for example in case of use as a bulk-filler, can result in high brittleness at low temperatures. Herein the amount of micro-talcum in parts by weight (pbw), is relative to the 100 pbw for the combined amount of X and Y. Addition of micro talcum in referenced amounts was further found to improve barrier properties against gas permeation.

[0104] The impact modified polyamide composition is obtainable by melt-mixing the PA, preferably the aliphatic polyamide (APA) and the modified polyolefin impact modifier (MIM) with the parameters in the amounts mentioned herein above. The impact modified polyamide composition can be prepared by, for example, melt-mixing the aliphatic polyamide, the MIM, and the optional further components to be added, as desired, by various methods known in the related art. Specifically, the impact modified polyamide composition can be obtained by charging the respective components simultaneously or sequentially into a mixing device such as a Henschel mixer, a V-type blender, a tumbler mixer, and a ribbon blender, heating and mixing them, and meltkneading the mixture using, for example, a single-screw extruder, a multi-screw extruder, a kneader or a Banbury mixer. In particular, if a device having excellent kneading performance, such as a multi screw extruder, a kneader, and a Banbury mixer is used, a high-quality impact modified polyamide composition in which the respective components are more uniformly dispersed is obtained.

[0105] The present invention also relates to a process for producing a molded article from the impact modified polyamide composition, and to a molded article made of the impact modified polyamide composition.

[0106] The process according to the present invention is a rotational molding process using the impact modified polyamide composition according to the present invention, and any special or preferred embodiment thereof, as described herein above. Any rotational molding process known in the art can be used.

[0107] Powder rotomolding products according to the invention can be processed on general rotomolding equipment. The heating system and temperature control of the mold are preferably well defined. Heating of the mold can, for example, take place with electrical heating elements and / or heat transfer with hot air in a conventional oven, but is not necessarily limited thereto.

[0108] Temperature control of the PIAT (peak internal air temperature) (e.g measurable by a thermocouple) can be used to control and / or optimize flow behavior, surface quality and optimum product properties. Powder rotomolding products according to the invention can be processed with a range of tool temperatures (240-270°C). PIAT temperatures between Tmelt + 20-40°C (for PA6: 240-260°C) can yield a suitable and homogeneous melt.

[0109] After heating (typically 5-10 minutes), fast cooling is recommended for the crystallization of the polymer melt and to avoid / mitigate oxidation of the inner surface.

[0110] The optimum processing temperature and / or time, can depend on the heat transfer, and can found by routine experimentation.

[0111] After feeding the polymer powder into the mold, a small flow of N2 to displace the air inside can be provided to mitigate discoloration and / or oxidation. To reduce the amount of N2 during the cycle a compromise can be to only add the N2 during the heating.

[0112] A method of manufacturing a rotomolded article comprises: dispensing an amount of a powdered product according to any of claims 1-6 within a mold; spreading the powdered product along a wall of the mold; heating the powdered product above a sintering temperature of the particles comprised in the powdered product; cooling the mold with contents, and releasing the article from the mold.

[0113] The molding of the impact modified polyamide composition according to the present invention by rotational molding method can be performed, for example, by the following method. For instance, firstly, a metal mold can be attached to a known rotational molding apparatus which can turn, invert, or move in a pendulum motion at single axis or multiple axes, and impact modified polyamide composition in the form of a powdered product, is charged in the metal mold. Then, the inside the metal mold can be heated to a temperature of between a) Tm+ 5 °C and b) Tm+ 80 °C. Herein, Tmis the melting temperature of the aliphatic polyamide. In other words, the metal mold can be heated to a temperature in the range of 5 - 80 °C above the melting temperature of the aliphatic polyamide. Good results were, for example, in a range of 30±5 °C above Tmof the PA.

[0114] The impact modified polyamide composition is molded while melting the polyamide, preferably APA, at this temperature. After that, the metal mold is cooled to a temperature between c) the glass transition temperature (Tg) of the polyamide and d) the temperature Tm-10 °C, to cool and solidify the rotational molded article. After that, the rotational molded article is removed from the metal mold. The cooling time varies depending on the thickness of the rotational molded article, but the cooling time is generally within the range of a couple of minutes to several hours. During rotational molding, in order to mitigate discoloring and the deterioration of the rotational molded article, an inert gas atmosphere such as nitrogen gas is preferred because it is free or substantially free of oxygen inside the metal mold. The impact modified polyamide composition can alternatively be charged to the metal mold in a melted form; for example, by first charging the impact modified polyamide composition to an extruder, heating and melting the impact modified polyamide composition in the extruder, and then extruding the melted impact modified polyamide composition directly into a preheated metal mold.

[0115] Herein, the Tgof the polyamide, mentioned above, is measured by the method according to ISO 11357-2:2020, with a heating ramp of 10 °C / min. Herein, the Tmof the aliphatic polyamide, mentioned above, is measured by the method according to ISO 11357-3:2018, with a heating ramp of 10 °C / min.

[0116] The present invention further pertains to a rotomolded article based on the powdered product as disclosed herein. Application of the powdered product is not particularly limited to a specific article. Inventers find the powdered product to be particularly beneficial for the manufacture, by rotomolding, of a container for storage of fluids, including but not limited to pressurized gases. The container having a wall structure bounding a volume for storing the fluid, wherein the wall structure is formed of a plurality of at least partly fused particles composed of the impact modified thermoplastic molding composition as described herein.

[0117] The container can be particularly equipped for storing permanent gases and / or lower hydrocarbon gases. A permanent gas is defined as a gas having a critical temperature Tc < -100°C, wherein the critical temperature can be defined as the highest possible temperature value at which the gas can be liquefied, such as H2, O2 and N2, preferably H2. Lower hydrocarbon gases include gases with 4 or fewer carbon atoms, such as CH4, C2H6, and C3H8, preferably CH4, C2H6, and / or mixtures thereof.

[0118] Advantageously the powdered product allows manufacturing of containers with a comparatively large dimension than with conventional injection molding. Additionally, the rotomolded product can be without a weld line. Rendering the container using rotomolding can eliminate seam lines which can be potential defects for mechanical failure and / or gas diffusion. In a preferred variation the container is a rotomolded part having a wall structure that extends continuously around a perimeter of said volume without a welded seam line.

[0119] In some embodiments there is provided a hydrogen tank comprising the container as disclosed herein.

[0120] The present invention further relates to a use of the impact modified thermoplastic composition according to the invention for the manufacturing of a container for storage of fluids, such as a pressurized gas, wherein the manufacturing comprises molding, preferably rotomolding.

[0121] The present invention further relates to a use of a maleic anhydride modified polyolefin impact modifier to mitigate phase segregation during or a result of melt processing, in particular rotomolding, of an impact modified thermoplastic composition comprising a polyamide, wherein the maleic anhydride (MAH) content is > 0.75 wt% relative to the weight of the modified polyolefin impact modifier.

[0122] EXAMPLES

[0123] The invention is further illustrated with the following examples and comparative experiments.

[0124] SET 1

[0125] Materials

[0126] Polyamide-1 Polyamide 6 (PA6), Tm=220 °C, relative viscosity (RV) at 0.01 g / ml in 96% sulphuric acid and at 25 °C of 2.51 (ex DSM).

[0127] Polyamide-2 Polyamide 6 (PA6), Tm=220 °C, relative viscosity (RV) at 0.01 g / ml in 96% sulphuric acid and at 25 °C of 2.09 (ex DSM).

[0128] Impact modifier-1 Acid modified ethylene-butylene polyolefin: 0.5 wt.% maleic anhydride; MFR 0.9 g / 10 min at 190°C, 2.16 kg; MFR 1.8 g / 10 min at 230 °C, 2.16 kg; Tg-65°C; density 870 kg / m3Shore A hardness 70 (ex Mitsui).

[0129] Impact modifier-2 Acid modified ethylene-butylene polyolefin: 1 wt.% maleic anhydride; MFR 0.6 g / 10 min at 190°C, 2.16 kg; MFR 1.2 g / 10 min at 230°C, 2.16 kg; Tg-65°C; density 866 kg / m3;Shore A hardness 55; (ex Mitsui).

[0130] Impact modifier-3 Acid modified ethylene-butylene polyolefin, 1.0 wt.% maleic anhydride; MFR 3.6 g / 10 min at 190 °C, 2.16 kg; MFR 7.4 g / 10 min at 230 °C, 2.16 kg; Tg-48°C; density 882 kg / m3(ex DOW).

[0131] Impact modifier-4 Ethylene 1-octene polyolefin; MFR 1.1 g / 10 min at 190°C, 2.16 kg; Tg-50 °C; density 885 kg / m3(ex Borealis).

[0132] Impact modifier-5 Acid modified ethylene-butylene polyolefin: 0.5 wt.% maleic anhydride; MFR 40 g / 10 min at 190 °C, 2.16 kg; MFR 70 g / 10 min at 230 °C, 2.16 kg; density 872 kg / m3Shore A hardness 72 (ex

[0133] Mitsui).

[0134] Impact modifier-6 Acid modified ethylene-butylene polyolefin: 0.75 wt.% maleic anhydride; MFR 11 g / 10 min at 190 °C, 2.16 kg; MFR 23 g / 10 min at 230 °C, 2.16 kg; Tg-65°C; density 896 kg / m3;Shore A hardness 89; (ex Mitsui).

[0135] Lubricant Calcium salt of long chain, saturated, linear carboxylic acids (montanic acids) (ex Clariant).

[0136] Talcum Microtalcum (ex Mineral Group).

[0137] Stabilizer-1 Irganox 1098 (N,N'-(hexane-1,6-diyl)bis[3-(3,5-di-tert-butyl-4- hydroxyphenyl)propanamide], primary antioxidant) (ex BASF)

[0138] Stabilizer-2 Chimassorb 944 (poly[[6-[(1 , 1 ,3,3-tetramethylbutyl)amino]-1 ,3,5- triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidinyl)imino]-1 ,6 hexanediyl[(2,2,6,6-tetramethyl-4-piperidinyl)imino]]): an oligomeric hindered amine light stabilizer (HALS) and heat stabilizer) (ex BASF).

[0139] Stabilizer-3 Cul / KBr (3 wt.% copper) (ex PolyAdd Services).

[0140] Aromatic PA Zytel HTN301, Tm=230-280 °C, density 1190 kg / ma (ex DuPont).

[0141] Glass fiber E6CR10-4,5-568H, filament diameter 9-11 micrometre, chop length 3.50-5.50 micrometer (ex Jushi).

[0142] Black colorant N54-1033, 40% solvent black ? (nigrosine) in PA6, density 1.19 g / cm3(ex Colloids).

[0143] Compounding

[0144] The molding compositions were produced in a ZSK25 twin-screw extruder with a flat temperature profile from 250 to 260 °C and with pelletization. The components

[0145] (see Table 1) were premixed and dosed at the throat. Unless specified otherwise, all compositions were prepared with an additive package consisting of 8.5 wt.% of a lubricant, 1.5 wt.% of talcum, 20 wt.% of Irganox 1098, 10 wt.% of Chimassorb 944, and 10 wt.% of Cul / KBr, the weight percentages (wt.%) based on the total weight of the additive package, all premixed in a masterbatch having 50 wt% of polyamide-1.

[0146] Comparative examples and compositions according to the invention listed under Tables 5-6 were prepared as specified above with additional of micro talcum and IM-4 to contents as specified in Tables 5-6.

[0147] Molding

[0148] Prior to molding, all materials were dried for 16 h at 120 °C inside a vacuum oven with a N2 purge. For the preparation of the test samples, injection molding was done on a Fanuc-2 injection machine, type a-S50iA, provided with an appropriate mold cavity, and applying a barrel temperature of 260 °C and a mold cavity temperature of 90 °C.

[0149] Relative Viscosity The relative viscosity of the polyamide polymers, respectively of the mixture thereof, was measured in sulphuric acid at a concentration of 1 g in 100 g m-cresol at a temperature of 25 °C by the method according to ISO 307. Flow resistance

[0150] The flow resistance was measured as a dynamic viscosity with dynamic mechanical spectroscopy (DMS) by the method according to ISO 6721-10, with loading time t=5 min, angular frequency 100 - 0.1 rad / s and 3 measuring points per decade. From these measurements, the complex viscosity (Eta*) at 0.1 rad / s is reported. Tensile properties DAM

[0151] The elongation at break was measured in a tensile test at -40 °C, with a drawing rate of 50 mm / min, on Type 1A test samples, by the method according to ISO 527- 2:2012.

[0152] Notched Impact resistance

[0153] The notched impact strength was measured at 23 °C by the method according to ISO 179-2:2020.

[0154] Falling weight impact resistance

[0155] The falling weight impact resistance was measured at -40 °C on injection molded plaques of 80*80*2 mm by the method according to ISO 6603-2-2000-10. The number of brittle failures out of 5 tests was reported.

[0156] Compositions and test results

[0157] The compositions according to the present invention (Examples, EX) and the Comparative Experiments (CE), and test results obtained with these Examples and Comparative Experiments are reported in Tables 1 , 2, 3, 4, 5, and 6. The wt% are based on the total weight of the impact modified polyamide composition.

[0158] Table 1. Compositions and test results for Comparative Experiments 1-9. a) Above 700 Pa.s: x = bad; 500-700 Pa.s: o = acceptable; below 500 Pa.s: oo = good; b) Below 17.5 %: x = bad; 17.5-20%: o = acceptable; above 20%: oo = good; c) Below 60 KJ / m3: x = bad; 60-80 KJ / m3: o = acceptable; above 80 KJ / m3: oo = good; d) 3-5 failures out of 5: x = bad; 2 failures out of 5: o = acceptable; 0-1 failures out of 5: oo = good.

[0159] The results in Table 1 show that the mechanical properties of a polyamide without impact modifier (CE-1) can be improved by addition of an impact modifier, however at the cost of an increased flow resistance (see CE-2; comprising an acid modified polyolefin impact modifier; CE-4 comprising a combination of an acid modified polyolefin impact modifier and a non-modified polyolefin). The flow can be improved by using a polyamide with a lower viscosity; however, the mechanical properties hardly increase, or even go down, in particular the impact resistance drops drastically upon further lowering the relative viscosity of the polyamide (see CE-3; comprising an acid modified polyolefin impact modifier; and CE-4 and CE-5 comprising the same combination of acid modified polyolefin impact modifier and non-modified polyolefin). Furthermore, the difference between the compositions CE-2 and CE-3 on one hand (comprising the single acid modified polyolefin impact modifier) and CE-4 and CE-6 on the other hand (comprising the same combination of acid modified polyolefin impact modifier and non-modified polyolefin) are limited, one performing slightly better in one property, less in another property. Moreover, all these comparative experiments failed in the impact test with the falling weight.

[0160] By further increasing the amount of acid modified polyolefin impact modifier in combination with the non-modified polyolefin, the impact resistance becomes better, but in an insufficient degree, and at the cost of a drastic reduction in flowability. This is illustrated with CE-8 in comparison with CE-7 and CE-5. When the polyamide of CE-8 is substituted with the polyamide with the lower viscosity, not only the flowability is improved, but also the impact resistance, which highly surprisingly, contrary to general observations, and contrary to the result observed above for CE-3 compared to CE-2, whereas the values for the elongation at break are also acceptable to good. However, also this composition fails in the impact test with the falling weight.

[0161] Table 2 shows the compositions and results for Comparative Experiments IQ- 12 and Examples A-D with a modified polyolefin impact modifier according to the present invention. The compositions of Comparative Experiments CE-10-12 comprise the modified polyolefin impact modifier in an amount of 20 wt.% based on the total weight of the composition. Although the impact resistance for CE-10 is at an acceptable level, the flow resistance is too high. The flow resistance can be lowered by using a polyamide with a lower relative viscosity (RV), as is illustrated by CE-11 and CE-12; however, the impact resistance decreases drastically, in particular when lowering further from a relative viscosity (RV) of 2.31 in CE-11 to 2.09 in CE-12. Meanwhile, also these compositions fail in the impact test with the falling weight, as shown for CE-11.

[0162] Table 2. Compositions and test results for Comparative Experiments 10-12 and A-D.

[0163] Ratings for a), b), c), and d) same as above in Table 1.

[0164] Contrary to the above results for CE-10-12, the compositions of A-D show good or improved results for all properties, including good values for falling weight resistance. However, since MAH content is below 0.75 wt% performance as to accumulation of impact modifier at grain boundaries as a result of prolonged thermal exposure leaves room for improvement. As for the properties reported in Table 2 CE-A comprises a higher amount of modified polyolefin impact modifier, compared to CE-11, which results not only in an improvement in impact resistance, and good values for the elongation at break, but also in retention of the flowability and, surprisingly, in an acceptable result for the falling weight impact test.

[0165] The differences in effects with the impact modifier combination used in the comparative experiments is clearly demonstrated with the comparison between CE-7 and CE-8 on one hand, and CE-11, CE-A and CE-B on the other hand, all based on the same mixture of polyamide. CE-7 comprises 20 wt.% of the impact modifier combination and has a Charpy impact resistance of 48.0 kJ / m2. In CE-8 the amount of the impact modifier combination is increased to 30 wt.%, which results in a moderate increase in Charpy impact resistance to 55.4 kJ / m2. CE-11 comprises 20 wt.% of the modified polyolefin impact modifier complying with the invention, showing a Charpy impact resistance of 56.15 kJ / m2. In A (CE-A), the amount of the modified polyolefin impact modifier is increased to 25 wt.%, which results in a significant increase in Charpy impact resistance to 86.7 kJ / m2. In B (CE-B), the amount of the modified polyolefin impact modifier is further increased to 30 wt.%, which results in a further increase in Charpy impact resistance to 96.0 kJ / m2. Further increasing the amount of modified polyolefin impact modifier, as in B, results in a further improvement in impact resistance, as well as in elongation at break, but also in retention of the flowability at an acceptable level, and in a good result for the falling weight impact test. Lowering the relative viscosity (RV) for the composition with 30 wt.% of modified polyolefin impact modifier, as is done in C (CE-C), in comparison with B, not only improves the flow resistance, but also even further improves the elongation at break, with retention of the impact resistance at a high level, which is in contrast with the opposite results for CE- 11 and CE12, and in a good result for the falling weight impact test, which is in clear contrast with the result for CE-9, mentioned above. As shown by D (CE-D), the amount of impact modifier can be even further increased, with retention of very good mechanical properties while flowability is still at an acceptable level.

[0166] Table 3 shows the compositions and test results for Examples E-F and Comparative Experiments 13-14, wherein the only difference is in the modified impact modifier. Examples E-F comprise a modified impact modifier according to the present invention, different from the one used in Examples A-D, but both having a melt flow rate (MFR), measured at 230 °C and a test load of 2.16 kg by the method according to ISO 1133:2011 , of at most 15 g / 10 min. As the results show, both Example E (EX-E) and Example F (EX-F) show good mechanical properties, including a good falling weight resistance at low temperature, in combination with a good flowability. As demonstrated in more detail with regard to experiments according to Set 2 the compositions according to Examples E and F show reduced accumulation of impact modifier at grain boundaries as a result of prolonged thermal exposure as compared to examples having a lower MAH content

[0167] Table 3. Compositions and test results for Examples E-F and Comparative Experiments 13-14

[0168] Ratings for a), b) c) and d) same as above in Table 1.

[0169] Comparative Experiments 13-14 (CE-13 and CE14) comprise different modified impact modifier, both not according to the present invention, whilst having a melt flow rate (MFR), measured at 230 °C and a test load of 2.16 kg by the method according to ISO 1133:2011, of at most 15 g / 10 min. As the results show, both Comparative Experiments show good flowability but fail in mechanical properties, in particular in the falling weight resistance at low temperature.

[0170] Table 4 shows various examples (Examples CE-G to M) with different compositions according to the present inventions, except that the MAH is below 0.75 wt%. While performing well in several aspects accumulation performance could be improved improvement. As for the mechanical characteristics listed Examples CE-G to CE-K show that the additive package can be varied widely without hardly affecting the mechanical properties while retaining a good flowability. Examples CE-L to CE-N show that polymers, other than the modified polyolefin impact modifier, can be added while retaining good mechanical properties in combination with an acceptable flowability, provided that the amount (Y) of modified polyolefin impact modifier in the composition is at least 22.5 pbw, relative to 100 pbw for the combined amount (Y) of modified polyolefin impact modifier (MIM) and the amount (X) of aliphatic polyamide (APA). This in contrast with compositions wherein the amount of modified impact modifier is below the minimum amount according to the present invention, even when the total amount of impact modifier is kept constant. In this respect, comparison of Example M (EX-M) and for Comparative Experiments 8 and 9 (CE-8 and CE-9) show relevant results. All three compositions have the same total amount of impact modifier (30 wt.%), however, CE-8 and CE-9 (compositions and results shown in Table 1) comprise less modified polyolefin impact modifier (MIM) and more non-modified polyolefin impact modifier, compared to EX-M. The composition according to CE-M shows an acceptable flowability and good mechanical properties, whereas Comparative Experiments CE-8 and CE-9 fail at least on either flowability or on the falling weight resistance at low temperature. Table 4. Compositions and test results for CE G-N.

[0171] Table 5 shows examples with different compositions according to the present invention, except for the MAH content. Examples CE-0 to CE-P show that compositions with a micro talcum content 0.5 and 1 .85 wt% (with respect to total mass of the composition) realize beneficial properties. From comparative examples 15-19 it follows that incorporation of an excess of other constituents Z, specifically exemplified for compositions having more than 30 pbw glass fiber (CE-15), more than 30 pbw of an aromatic polyamide (CE-16), more than 30 pbw of an aromatic PA + GF (CE-17), respectively more than 2 pbw of micro talcum (CE-18 and CE-19), negatively affects one or more of: flow properties, tensile properties, notched impact resistance, and falling weight resistance.

[0172] Note that for samples according to the invention, i.e. having their respective constituents within the claimed ranges and no-excess of others (components Z) such negative effects were not observed. In terms of impact resistance, the results confirm good performance for samples having up to 1 pbw of micro talcum, acceptable impact rating for samples with up to 2 pbw micro talcum, and comparatively reduced performance for samples with a higher micro talcum content. Table 5. Compositions and test results for CE-0 to CEP and CE-15 to CE-19

[0173] Ratings for a), b) c) and d) same as above in Table 1. e) 0 failures out of 4 tests.

[0174] Table 6 displays results for example (EX-R) with a compositions according to the present inventions as well as comparative examples CE-Q, CE-20 and CE-21. It follows that addition of more than 10 pbw of an unmodified IM (IM-4) negatively affects rotomoldability, especially in terms of displaying a comparatively poor flowability, which is believed to be occasioned by a phase inversion to a system having a discontinuous polyamide phase in an olefin matrix. In contrast examples L, M, Q and R, having no excess of unmodified impact modifier, display good performance in flowability, tensile properties, and falling weight resistance, in combination with an at least acceptable performance in terms of impact resistance. Differences in performances in flow properties and impact rating between EX-R and EX-Q are believed to related to differences in maleic anhydride content. Inventors find that rotomolded articles based on composition according to the invention, such as EX-3, can advantageously combined good mechanical characteristics with mitigated phase segregation (see also results of samp les according to Set 2).

[0175] Table 6. Compositions and test results for and Examples Q-R and Comparative Experiments 20-21

[0176] Ratings for a), b) c) and d) same as above in Table 1 .

[0177] SET 2

[0178] Materials

[0179] Impact modifier-A TAFMER, MH7010\8000A Ex Mitsui, MAH modified impact modifier, MAH content 0.5 wt%, supplier: Mitsui, density 870 kg / m3, MFR (190°C, 2.16 kg) 0.9.

[0180] Impact modifier-B TAFMER DF710, Unmodified impact modifier, supplier: Mitsui, density 870 kg / m3, MFR (190°C,2.16 kg) 1.2.

[0181] Impact modifier-C TAFMER MH7020, Tafmer MH7020: MAH modified impact modifier, supplier: Mitsui, MAH content 1 wt%, density 870 kg / m3, MFI (190°C, 2.16 kg) 0.7

[0182] Impact modifier-D TAFMER MH5040: MAH modified impact modifier, supplier: Mitsui, MAH content 2 wt%, density 870 kg / m3, MFI (190°C, 2.16 kg) 0.5

[0183] MB-Carrier-A MB carrier polymer: Polyamide-1 (SET 1)

[0184] Stabilizer-A Oligomeric hindered amine light stabilizer, Hostavin N 30 P, ex Clariant

[0185] Stabilizer-B Phosphite antioxidant ADK STAB PEP-36, Ex Adeka

[0186] Stabilizer-C IRGANOX 1098 (N,N'-(hexane-1 ,6-diyl)bis[3-(3,5-di-tert- butyl-4-hydroxyphenyl)propanamide], primary antioxidant) (ex BASF)

[0187] Stabilizer-D Cul / KBr (3 wt.% copper) (ex PolyAdd Services).

[0188] Lubricant-A LICOMONT CAV 102, Calcium salt of long chain, saturated, linear carboxylic acids (montanic acids) (ex Clariant). Polyamide-A Novamid® 1007J - Polyamide 6 (PA6), supplier Envalior, viscosity 96% H2SO4, 25 C, 0.01 g / L: 2.09 (same Polyamide-2 in SET 1)

[0189] Polyamide-B Durethan B 24 00000 (PA6), supplier Envalior, relative viscosity 96% H2SO4, 25 C, 0.01 g / L: 2.36

[0190] Unless stated to the contrary materials were compounded as identified above. Masterbatch (MB) carrier-A polymer, was added as part of an additive package including stabilizer and / or further additives as appropriate. Inventors find it imparts a negligible effect on the performance (including flow and mechanical properties) of the composition.

[0191] Powder

[0192] Various powders were prepared by cryomilling and / or ambient milling from compositions compounded using processes described above. As indicated powders were sieved or fractionated.

[0193] Rotomolding

[0194] Rotomolded articles were made on a standard rotomolding setup using a two-halve shell metal mold using the procedure as described hereinabove, both in presence and absence of air. Samples prepared under N2 generally displayed les discoloration.

[0195] Flow characteristics

[0196] Powder flow properties, angle of repose and cohesive index, have been determined as described by A. Neveu, F. Francqui, G. Lumay in Measurement 200 (2022) 111548, which is hereby incorporated by reference. Flow characteristics were measured at 2, 4, 6, 8 & 10 rpm.

[0197] Compositions and test results

[0198] Samples according to the present invention (Examples, E2) and the Comparative Experiments (C2), and test results obtained with these samples and Comparative Experiments are reported in Tables 7 and further. The wt% are based on the total weight of the weight of the impact modified polyamide composition.

[0199] Table 7. Compositions for comparative examples (C2-#) and examples according to the invention (E2-#).

[0200] Batches of powders for rotomolding experiments have been prepared for compositions as listed in Table 7 by milling under ambient or cryogenic conditions. Rotomoldability has been confirmed for all powders, including powders having a size distribution between a biggest particle size a d50= 599.78 pm, and a d90= 739.66 pm and a largest particle size characterized by a d50= 599.78 pm, d90= 739.66 pm.

[0201] Table 8 summarizes representative powder flow characteristics and rotomolded wall characteristics for powdered products that differ only in size distribution characteristics. For powdered based on compositions with different MAH content similar trends are observed.

[0202] Table 8: powder flow characteristics and wall thickness homogeneity of products based on powders that differ only in size characteristics. a) Cohesion index (values@6 rpm), lower values correspond to higher flowability b) Dynamic angle of repose (values @6rpm), lower values correspond to higher flowability. c) Score values: o = acceptable, + = good, ++ = very good, - = poor, -- = very poor.

[0203] It was observed that rotomolded articles based on the sample with the biggest size particles were found to have comparatively darker brown discoloration, which may be an indication of comparatively higher surface degradation during rotomolding.

[0204] Figures 2-4 illustrate experimental observations for rotomolded containers based on powders having a composition with: 0.5 wt% MAH (FIG 2: C2-3); 1 wt% MAH (FIG 3: E2-2); and 2 wt% MAH (FIG 4: E2-4), whereby the A-Figures are pictures of the upper part of each rotomolded container 1 , the B-Figures are light table photos of a bottom portion of each tank, the C-figures are optical micrographs of a respective slice across a thickness of the wall 3 of each container, and the D-figures are scanning electron microscopy images detailing the internal structure of each respective wall. All articles were realized under similar rotomolding conditions.

[0205] As can be seen by comparing Figs 2a and 2b with Figs 2a and 3b and with Figs 4a and 4b respectively, the color of the wall at its surface facing the interior of the tank is lightest for samples with 1 wt% MAH (E2-2) and highest for samples with 2 wt% MAH (E2-4), with C2-2 in between. Scores for C2-2, E2-2 and E2-4 are in this order '++’, and Sample C2-1 (not illustrated) was rated see c) under table 8 for scoring scale.

[0206] As best seen in Fig 2B by variations in color intensity the sample with 0.5 wt% was observed to have the largest surface roughness. Samples E2-2 and E2-4 were each found to have a smooth inner surface (score '++’), whereas C2-1 was even less smooth than C2-2.

[0207] As can be in by comparing Figs 2C and 2C with Figs 3C and 3C and with Figs 40 and 40 respectively the sample having only 0.5 wt% of MAH has the highest degree of accumulation at boundaries between adjacent grains. This accumulation at grain boundaries forms in interconnected network of a comparatively MIM-richer phase that extends between opposing ends of the molded wall. For samples with 1 wt% and 2 wt% MAH accumulation of MIM is essentially non-observable. The inventors did not observe an interconnected network of an MIM-rich phase that extends across opposing faces of the wall for samples with an MAH content > 0.75 wt%.

[0208] Note that for each wall a small fraction of distributed and isolated pores (visible as largely round lighter colored areas in Fig 2C, 3C and 4C) was observed. These pores are believed to relate gas present between adjacent powder particles upon charging of the rotomold and unable to degas during rotomolding and fusing of the powder.

[0209] Inventors find that mitigating MIM network formation has a particular positive contribution to reducing gas permeation rates across the contained wall. As such the overall permeability across the rotomolded wall is found to increase with decreasing accumulation. Rotomolded articles based on powders according to the invention and having no visible accumulation of MIM are found to offer permeation rate performance that is highly similar to articles based on the same composition but made under less demanding thermo-oxidative conditions, such as injection molding.

[0210] Presence of isolated pores was found to have a minor contribution to overall permeability. This relation was confirmed by permeation modelling experiments where the introduction of an interconnected network of rubbery phases within a PA matrix was found to correspond to a 38% higher permeation rate than without such network, despite accounting for only 1% of the total volume. In contrast, an introduced volume of 1% of isolated pores was found to correlate to an increase in permeation rate of only 3%. In addition, inventors found that permeation rate (O2) in rotomolded products based on sample C2-2 was 35% higher than for an injection molded product based on the same composition. Inventors find the poorer performance at rotomolded articles can advantageously be decreased or even eliminated by employing powders according to the invention that are less prone to accumulation.

[0211] Clauses

[0212] In addition to the subject matter and variations described herein above the pertinent disclosure additionally relates to the embodiments according the clauses listed.

[0213] Clause 1. Rotomolding product containing free flowing particles formed of an impact modified thermoplastic composition comprising: a polyamide (PA), and a polyolefinic impact modifier, wherein the polyolefinic impact modifier has a maleic anhydride (MAH) content of at least 0.75 wt% relative to the combined weight of polyolefinic impact modifier comprised in the rotomolding product. Clause 2. The product according to any of the preceding clauses, wherein the MAH content is greater than or equal to 0.75 wt% and less than or equal to 3 wt%, preferably between 0.75 and 2 wt%, more preferably between 0.75 and 1.5 wt%.

[0214] Clause 3. The product according to any of the preceding clauses, wherein the molding composition comprises

[0215] X parts by weight (pbw) of the polyamide as an aliphatic polyamide (APA) as the polyamide, and

[0216] Y parts by weight (pbw) of the polyolefinic impact modifier, and wherein the aliphatic polyamide APA has a relative viscosity (RV), measured at 0.01 g / ml in 96% sulphuric acid and at 25 °C by the method according to 180307:2019, of at most 2.50; the polyolefinic impact modifier has a melt flow rate (MFR), measured at 230 °C and a test load of 2.16 kg by the method according to ISO 1133:2011 , of at most 15 g / 10 min; and the sum of X and Y is 100 pbw, and wherein

[0217] X is at most 77.5 pbw and Y is at least 22.5 pbw, and for the relative viscosity (RV) of the aliphatic polyamide (APA) up to and including 2.20, X is at least 60 pbw and Y is at most 40 pbw; for the relative viscosity (RV) of the aliphatic polyamide (APA) in a range between above 2.20 and up to and including 2.33, X is at least 65 pbw and Y is at most 35 pbw; and for the relative viscosity (RV) of the aliphatic polyamide (APA) in a range between above 2.33 and up to and including 2.50, X is at least 70 pbw and Y is at most 30 pbw.

[0218] Clause 4. The product according to clause 3, wherein further constituents other than the APA and the polyolefinic impact modifier as comprised in the molding composition add up to no more than 30 parts by weight (pbw) relative to 100 parts by weight of the APA and the polyolefinic impact modifier combined and wherein a nonmodified polyolefin content adds up to no more than 10 parts by weight (pbw) relative to 100 parts by weight of the APA and the polyolefinic impact modifier combined. Clause 5. The product according to any of the preceding clauses, wherein the polyamide is an AB polyamide, preferably comprising repeat units selected from the group consisting of: caprolactam; enantolactam; undecanelactam; dodecanelactam; a- pyrrolidone; and / or a-piperidone; and a copolymer or mixture thereof; most preferably caprolactam. Clause 6. The product according to any of the preceding clauses, wherein the molding composition comprises 0.001 - 1 pbw of micro talcum relative to 100 parts by weight of the polyamide and the polyolefinic impact modifier combined.

[0219] Clause 7. A method of manufacturing a rotomolded article comprising dispensing an amount of a powdered product according to any of clauses 1-6 within a mold spreading the powdered product along a wall of the mold heating the powdered product above a sintering temperature of the particles comprised in the powdered product cooling contents of the mold, and releasing the article from the mold.

[0220] Clause 8. Rotomolded article based on the powdered product according to any of clauses 1-6.

[0221] Clause 9. The article according to clause 8, wherein the article is a container (1) for storage of a fluid, such as a pressurized gas, the container having a wall structure (2) bounding a volume (3) for storing the fluid, wherein the wall structure is formed of a plurality of fused particles composed of the impact modified thermoplastic molding composition as in any of claims 1-6.

[0222] Clause 10. The container according to clause 9, wherein the container is a rotomolded part having a wall structure that extends continuously around a perimeter of said volume without a welded seam line.

[0223] Clause 11. A hydrogen tank comprising the container according to any of the preceding clauses 9-10.

[0224] Clause 12. Use of an impact modified thermoplastic composition comprising: a polyamide (PA), preferably an aliphatic polyamide (APA), and an polyolefinic impact modifier having a maleic anhydride (MAH) content of at least 0.75 wt% relative to the combined weight of polyolefinic impact modifiers comprised in the composition, wherein the polyolefinic impact modifier has a maleic anhydride (MAH) content of at least 0.75 wt% for manufacturing of a container for storage of a fluid, wherein the manufacturing comprises molding, preferably rotomolding.

[0225] Clause 13. Use of a maleic anhydride modified polyolefin impact modifier to mitigate phase segregation as a result of melt processing, in particular rotomolding, within an impact modified thermoplastic composition comprising a polyamide, preferably an aliphatic polyamide, wherein the maleic anhydride (MAH) content is > 0.75 wt% relative to the combined weight of polyolefinic impact modifiers comprised in the composition.

Claims

CLAIMS1 . Powdered product, especially for application in rotomoulding, said powdered product containing free flowing particles formed of an impact modified thermoplastic composition comprising: a polyamide (PA), and a polyolefinic impact modifier, said polyolefinic impact modifier comprising at least a maleic acid modified polyolefinic impact modifier constituent (MIM), and optionally one more further polyolefinic impact modifier constituent different from the MIM, such as a non-modified polyolefinic impact modifier constituent, wherein: the polyamide is an aliphatic polyamide (APA) having a relative viscosity (RV), measured at 0.01 g / ml in 96% sulphuric acid and at 25 °C by the method according to IS0307:2019, of at most 2.50; the polyolefinic impact modifier has a melt flow rate (MFR), measured at 230 °C and a test load of 2.16 kg by the method according to ISO 1133:2011 , of at most 15 g / 10 min; and the impact modified thermoplastic composition comprises at least 22.5 pbw of the polyolefinic impact modifier per 100 parts of the sum of the polyamide and the polyolefinic impact modifier employed; and wherein the polyolefinic impact modifier has a maleic anhydride (MAH) greater than or equal to 0.75 wt% and less than or equal to 3 wt%, relative to the combined weight of the polyolefinic impact modifier comprised in the product.

2. The powdered product according to any of the preceding claims, wherein the MAH content is between 0.75 and 2 wt%, more preferably between 0.75 and 1.5 wt%.

3. The powdered product according to any of the preceding claims, wherein the thermoplastic composition comprisesX parts by weight (pbw) of the polyamide as an aliphatic polyamide (APA) as the polyamide, andY parts by weight (pbw) of the polyolefinic impact modifier, and wherein the aliphatic polyamide APA has a relative viscosity (RV), measured at 0.01 g / ml in 96% sulphuric acid and at 25 °C by the method according to IS0307:2019, of at most 2.50;the polyolefinic impact modifier has a melt flow rate (MFR), measured at 230 °C and a test load of 2.16 kg by the method according to ISO 1133:2011, of at most 15 g / 10 min; and the sum of X and Y is 100 pbw, and whereinX is at most 77.5 pbw and Y is at least 22.5 pbw, and for the relative viscosity (RV) of the aliphatic polyamide (APA) up to and including 2.20, X is at least 60 pbw and Y is at most 40 pbw; for the relative viscosity (RV) of the aliphatic polyamide (APA) in a range between above 2.20 and up to and including 2.33, X is at least 65 pbw and Y is at most 35 pbw; and for the relative viscosity (RV) of the aliphatic polyamide (APA) in a range between above 2.33 and up to and including 2.50, X is at least 70 pbw and Y is at most 30 pbw.

4. The powdered product according to claim 3, wherein further constituents other than the APA and the polyolefinic impact modifier as comprised in the molding composition add up to no more than 30 parts by weight (pbw) relative to 100 parts by weight of the APA and the polyolefinic impact modifier combined and wherein a non-modified polyolefin content adds up to no more than 10 parts by weight (pbw) relative to 100 parts by weight of the APA and the polyolefinic impact modifier combined.

5. The powdered product according to any of the preceding claims, wherein the polyamide is an AB polyamide, preferably comprising repeat units selected from the group consisting of: caprolactam; enantolactam; undecanelactam; dodecanelactam; a-pyrrolidone; and / or a-piperidone; and a copolymer or mixture thereof; most preferably caprolactam.

6. The powdered product according to any of the preceding claims, wherein the molding composition comprises 0.001 - 1 pbw of micro talcum relative to 100 parts by weight of the polyamide and the polyolefinic impact modifier combined.

7. A method of manufacturing a rotomolded article comprising dispensing an amount of the powdered product according to any of claims 1-6 within a mold spreading the powdered productheating the powdered product above a sintering temperature of the particles comprised in the powdered product cooling the contents of the mold, and releasing the article from the mold.

8. Rotomolded article based on the powdered product according to any of claims 1-6.

9. The article according to claim 8, wherein the article is a container (1) for storage of a fluid, such as a pressurized gas, the container having a wall structure (2) bounding a volume (3) for storing the fluid, wherein the wall structure is formed of a plurality of fused particles composed of the impact modified thermoplastic molding composition as in any of claims 1-6.

10. The container according to claim 9, wherein the container is a rotomolded part having a wall structure that extends continuously around a perimeter of said volume without a welded seam line.

11. A hydrogen tank comprising the container according to any of the preceding claims 9-10.

12. Use of an impact modified thermoplastic composition comprising: a polyamide (PA), preferably an aliphatic polyamide (APA), and an polyolefinic impact modifier said polyolefinic impact modifier comprising at least a maleic acid modified polyolefinic impact modifier constituent (MIM) [and optionally one more further polyolefinic impact modifier constituent different from MIM, such as non-modified polyolefinic impact modifier constituent for the manufacturing of a container for storage of a fluid, wherein the polyamide is an aliphatic polyamide (APA) having a relative viscosity (RV), measured at 0.01 g / ml in 96% sulphuric acid and at 25 °C by the method according to IS0307:2019, of at most 2.50; the polyolefinic impact modifier has a melt flow rate (MFR), measured at 230 °C and a test load of 2.16 kg by the method according to ISO 1133:2011, of at most 15 g / 10 min; the impact modified thermoplastic composition comprises at least 22.5 pbw of the polyolefinic impact modifier per 100 parts of the sum of the a polyamide and the polyolefinic impact modifier employed;wherein the polyolefinic impact modifier has a maleic anhydride (MAH) greater than or equal to 0.75 wt% and less than or equal to 3 wt%, relative to the combined weight of the polyolefinic impact modifier comprised in the product; and wherein the manufacturing comprises molding, preferably rotomolding.

13. Use of a maleic anhydride modified polyolefin impact modifier to mitigate phase segregation as a result of melt processing, in particular rotomolding, within an impact modified thermoplastic composition comprising a polyamide, preferably an aliphatic polyamide, said polyolefinic impact modifier comprising at least a maleic acid modified polyolefinic impact modifier constituent (MIM) [and optionally one more further polyolefinic impact modifier constituent different from MIM, such as a non-modified polyolefinic impact modifier constituent, wherein the polyolefinic impact modifier has a maleic anhydride (MAH) content greater than or equal to 0.75 wt% and less than or equal to 3 wt%, relative to the combined weight of polyolefinic impact modifiers comprised in the composition.

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