NZ622629B2 - Rotomoulded articles comprising a layer of polyolefin and polyester - Google Patents

Abstract

rotomoulded article comprising one or more layers wherein a layer A comprises: from 50 to 99.4 wt% of a polyolefin, from 0.5 to 50 wt% of a polyester, wherein said polyester is an aliphatic polyester selected from polyhydroxyalkanoate, poly(lactic acid), polycaprolactone, copolyester and polyesteramides, from 0.1 to 20 wt% of a co- or ter-polymer comprising: a) 50 to 99.9 wt% of an ethylene or a styrene monomer, b) 0.1 to 50 wt% of an unsaturated anhydride-, epoxide- or car- boxylic acid-containing monomer, c) 0 to 50 wt% (meth)acrylic ester monomer. amides, from 0.1 to 20 wt% of a co- or ter-polymer comprising: a) 50 to 99.9 wt% of an ethylene or a styrene monomer, b) 0.1 to 50 wt% of an unsaturated anhydride-, epoxide- or car- boxylic acid-containing monomer, c) 0 to 50 wt% (meth)acrylic ester monomer.

Description

Rotomoulded articles comprising a layer of polyolefin and ter Field of the invention The invention pertains to polyolefin- and polyester-comprising rotomoulded articles.

Background of the invention The process of rotational moulding, also called rotomoulding, of plastic has been known since the 1940s for the preparation of hollow plastic articles.

This process consists of adding a thermoplastic polymer into a mould, rotating the mould so that all the points of the internal surface of the mould are in contact with the polymer while heating the mould, so as to deposit the aforementioned molten polymer on the internal surface of the mould. Thereafter, a stage of cooling allows the solidification of the plastic article, which is then removed from the mould.

Rotational moulding is ageous because it avoids applying stress and strain to the plastic, which generally occurs in other ormations, for example in injection moulding.

Indeed, the c does not undergo malaxation or compaction as in an extruder or in injection moulding. onal moulding is particularly suitable for preparing large-sized es, such as furniture, tanks, drums, reservoirs etc.

The most ly used polymer in rotational ng is polyethylene, but other polymers such as vinyl polychlorides (PVC), ides, polycarbonates and polypropylenes can also be used. However, alone, all of these polymers tend to shrink somewhat and deform within the mould, which causes considerable awal from the mould and non-uniform wall thicknesses. In addition, these polymers, used alone, are characterized either by slow coalescence, or by a raised melting point, which increases the duration of the production cycle. Polyesters, on the other hand, often lack in good thermal and mechanical properties.

There thus exists a need to produce articles by rotational moulding with polymer compositions, which coalesce more rapidly and which make it possible to obtain articles with minimal shrinkage and warpage.

The object of this invention is thus to provide rotationally moulded oulded) articles comprising polyolefin having less shrinkage and/or e.

Another object of this invention is to provide rotomoulded articles having a uniform wall thickness.

Another object of this invention is to provide rotomoulded es presenting a good aspect of internal and external surfaces, without any bubbles, ripples, or other defects.

Another object of this invention is to provide rotomoulded articles with good mechanical properties, in particular improved impact strength.

Another object of this ion is to provide ulded articles with good ical properties, in particular stiffness.

At least one of the objects mentioned above is carried out with the present invention.

The applicant found in a surprising way that by using a ter, for example poly(lactic acid) together with a efin, for example polyethylene, the disadvantages mentioned above can be overcome.

Summary of the invention The invention covers a rotomoulded article comprising one or more layers wherein a layer A comprises:  from 50 to 99.5 wt% of a polyolefin, preferably 60 to 99.4 wt%;  from 0.5 to 49.9 wt% of a polyester, preferably 1 to 30 wt%;  from 0 to 20 wt% of a co- or ter-polymer, preferably 0.1 to 20 wt%, comprising a) 50 to 99.9 wt% of an ethylene or a styrene r; b) 0.1 to 50 wt% of an unsaturated anhydride-, epoxide- or carboxylic acid-containing monomer; and c) 0 to 50 wt%, preferably 0.1 to 30 wt%, (meth)acrylic ester monomer.

Preferably, the invention covers a rotomoulded article comprising one or more layers n a layer A comprises:  from 50 to 99.4 wt% of a polyolefin, preferably 60 to 99.4 wt%;  from 0.5 to 49.9 wt% of a polyester, wherein said polyester is an aliphatic polyester ed from polyhydroxyalkanoate, poly(lactic acid), polycaprolactone, copolyesters and polyesteramides, preferably 1 to 30 wt%;  from 0.1 to 20 wt% of a co- or ter-polymer, preferably 0.1 to 20 wt%, comprising a) 50 to 99.9 wt% of an ethylene or a e monomer, b) to 50 wt% of an unsaturated anhydride-, epoxide- or carboxylic acid-containing monomer; and 2012/067529 c) to 50 wt%, preferably 0.1 to 30 wt%, (meth)acrylic ester monomer.

The article comprising layer A is preferably a mono-, bi- or tri-layered rotomoulded article.

The polyolefin is preferably polyethylene or polypropylene.

The polyester is preferably an aliphatic polyester. The majority of aliphatic polyesters (e.g. polyhydroxyalkanoate (PHA), poly(lactic acid) (PLA), polycaprolactone (PCL), copolyesters, polyesteramides, etc being able from renewal resources and/or being biodegradable constitutes an additional advantage when added in combination with polyolefins, currently used alone. Preferably the aliphatic ter is a poly(lactic acid).

The unsaturated anhydride-, epoxide-, or carboxylic acid-containing monomer is preferably ed from maleic anhydride, or glycidyl methacrylate. Preferably, it is present in an amount ranging from 0.2 to 30 wt% of the co- or ter-polymer.

The (meth)acrylic ester r is preferably selected from methyl, ethyl, n-butyl, iso- butyl, 2-ethylhexyl, or n-octyl (meth)acrylate. It is preferably present from 0.5 to 40wt%, more preferably 1 to 30 wt%, of the terpolymer.

The article may comprise a further layer B1 comprising from 50 to 100 wt% of an aliphatic polyester selected from polyhydroxyalkanoate, poly(lactic acid), polycaprolactone, copolyesters and polyesteramides; preferably from 60 wt% to 100 wt%, more preferably from 70 wt% to 100 wt%. Said layer B1 is preferably adjacent to layer A. Preferably the aliphatic polyester is a poly(lactic acid).

In a ular embodiment, the article may se layers A and B1, wherein: layer A is the outer layer, and layer B1 is the inner layer.

The article may comprise a r layer B comprising from 50 to 100 wt% of a polyolefin, which is ably adjacent to layer A. The polyolefin of said layer B is preferably a polyethylene. The efin can be different from the polyolefin of layer A. The polyolefin, being preferentially polyethylene, of said layer B is preferably foamed.

In a particular embodiment, the article may se layers A, B and B1, n layer A is the outer layer, layer B is the intermediate layer adjacent to layer A and layer B1, and layer B1 is the inner layer.

The article may comprise yet a further layer C comprising from 50 to 100 wt% of a polyolefin, which is preferably adjacent to layer B. The polyolefin can be different from the efin of layer A. The polyolefin of said layer C is preferably a polyethylene.

In a particular embodiment, the article may comprise, or consist of the three layers A, B and C, wherein: 0 layer A is the outer layer, 0 layer B is the intermediate layer adjacent to layer A and layer C, preferably comprising a foamed polyethylene from 50 to 100 wt%, 0 layer C is the inner layer, ably comprising polyethylene from 50 to 100 wt%.

In this case, layer C can be identical to layer A.

In particular embodiments, the article comprises at least one cavity which is ed with a polyurethane (PU); preferably a polyurethane foam.

The present invention also encompasses a polyurethane filled rotomoulded article comprising one or more layers wherein a layer A comprises: 0 from 50 to 99.5 wt% of a polyolefin, preferably 50 to 99.4 wt%; 0 from 0.5 to 50 wt% of a polyester, ably 1 to 30 wt%; 0 from 0 to 20 wt% of a co- or ter-polymer, preferably 0.1 to 20 wt%, comprising - 50 to 99.9 wt% of an ethylene or a styrene monomer; - to 50 wt% of an unsaturated anhydride-, epoxide- or carboxylic acid-containing monomer; - 0 to 50 wt%, preferably 0.1 to 30 wt%, acrylic ester monomer.

Such an e can be a can, a tank, car part, preferably a car door or car body.

Brief description of the s Figure 1 depicts a rotomoulded bottle.

Figure 2 shows the temperature cycle of a rotomoulding s to prepare a single- layered article.

Figure 3 shows a photograph of a car part.

Figures 4a and 4b show a diagrammatic image of a car part from above and from the side.

Figure 5 shows the temperature cycle of a rotomoulding process to prepare a multi- layered e.

Figure 6 represents a graph plotting the modulus as a function of temperature for resin 1 and composition 14.

Figure 7 represents the 3D volume shrinkage expressed in % with respect to the mould volume for resins 1 and 2 and compositions 7, 8, 9, 13, 14 and 15.

Figure 8 represents the g behavior expressed in % for resins 1 and 2 and compositions 8 and 9.

Figure 9 represents a photograph of a two-layers comparative article having an outer layer made of resin 2, and a foamed inner layer.

Figure 10 represents a graph plotting the Bell ESCR expressed in hours for resin 1 and composition 13 and 14.

Figure 11 represents a photograph of the cross section of a single-layered e made with composition 14 and filled with a PU foam.

Figure 12 represent a photograph of the cross section of a single-layered article made with composition 14 and filled with a PU foam, a the cross section of a single-layered article made with resin 2 and filled with a PU foam.

Detailed Description of the Invention 1 Layer A The rotomoulded article of the invention comprises one or more layers wherein a layer A comprises: 0 from 50 to 99.5 wt% of a polyolefin; ably from 50 to 99.4 wt% of a polyolefin; o from 0.5 to 50 wt% of a polyester, preferably wherein said polyester is an aliphatic polyester selected from poly(lactic acid), polyhydroxyalkanoate, polycaprolactone, esters and polyesteramides; more ably wherein said polyester is an aliphatic polyester selected from poly(lactic acid), polyhydroxyalkanoate, polycaprolactone, and polyesteramides; more preferably n said polyester is an aliphatic polyester selected from poly(lactic acid), polycaprolactone, and polyesteramides; o from 0 to 20 wt% of a co- or lymer; preferably from 0.1 to 20% of a co- or ter- polymer comprising: a) 50 to 99.9 wt% of an ethylene or a styrene monomer, b) 0.1 to 50 wt% of an unsaturated ide-, epoxide- or ylic acid-containing monomer, c) 0 to 50 wt%, preferably 0.1 to 30 wt%, (meth)acrylic ester monomer.

The optional co- or ter-polymer when used, can be present from 0.1 to 20 wt% of layer A, more preferably from 0.1 to 15 wt% of layer A. 1.1. The ol olefin e. . ol eth lene The efin is present preferably from 50,60, 65, 70, 75 or 80 up to 90, 95, 96, 97, 98, 99, 99.4, 99.5 wt% of layer A. In particular, the polyolefin can be present in amounts ranging preferably from 70 to 95 wt% of layer A, more preferably 75 to 90 wt%.

The efin can be selected from polyethylene, polypropylene, polybutene or polyhexene.

Preferably, the polyolefin is polyethylene. With hylene herein it is meant a polyethylene comprising at least 50 wt% of ethylene monomers. The polyethylene may comprise up to 50 wt% of alpha-olefin comonomers selected from alpha-olefins having from 3 to 12 carbon atoms. Preferably, the comonomer is selected from propylene, n- , iso-butene, n-pentene, iso-pentene, n-butene or iso-butene.

The polyethylene can be prepared with a Ziegler-Natta catalyst or a -site catalyst, such as a metallocene, ing to any known polymerization process in the art.

Preferably, the polyethylene is ed with a single-site catalyst, in particular with a metallocene catalyst. This induces a narrow molecular weight distribution, r comonomer insertion, and uniform comonomer distribution. This means such a polyethylene preferably has a narrow molecular weight distribution of from 1 to 5 (measured by GPC) and a narrow comonomer distribution index (CDBI) i.e. at least 50%, preferably at least 60%, more preferably at least 75%, measured by TREF rature rising elusion onation). Any metallocene known in the art can be used to prepare the polyethylene. In one embodiment, the metallocene can be an ged metallocene, for example, selected from the group comprising bis(iso-butylcyclopentadienyl) zirconium dichloride, bis(pentamethylcyclopentadienyl) zirconium dichloride, bis(tetrahydroindenyl) zirconium dichloride, bis(indenyl) zirconium dichloride, bis(1,3-dimethylcyclopentadienyl) zirconium dichloride, bis(methylcyclopentadienyl) zirconium dichloride, bis(nbutylcyclopentadienyl ) ium dichloride, and clopentadienyl) zirconium dichloride; and preferably selected from the group comprising bis(cyclopentadienyl) zirconium dichloride, bis(tetrahydroindenyl) zirconium dichloride, bis(indenyl) ium dichloride, and bis(1-methylbutyl-cyclopentadienyl)zirconium dichloride. In another embodiment, the metallocene can be a bridged metallocene, for example, selected from the group comprising ethylene bis(4,5,6,7-tetrahydroindeny|) zirconium dichloride, ethylene bis(1- indenyl) zirconium dichloride, dimethylsilylene bis(2-methylphenyl-indenyl) zirconium dichloride, dimethylsilylene bis(2-methyl-1H-cyclopenta[a]naphthalenyl) zirconium dichloride, cyclohexylmethylsilylene bis[4-(4-tert-buty|phenyl)—2-methyl-indenyl] zirconium dichloride, dimethylsilylene bis[4-(4-tert-buty|phenyl)(cyclohexylmethyl)inden- 1-yl] zirconium dichloride. Bridged bis(tetrahydroindenyl) metallocenes are preferred, in ular ethylene bis(4,5,6,7-tetrahydroindenyl) zirconium ride.

The polyethylene preferably has a density of at least 0.900 g/cm3, more ably at least 0.910 g/cm3, even more preferably of at least 0.920 g/cm3 and most preferably of at least 0.930 g/cm3. It is of at most 0.965 g/cm3, preferably of at most 0.960 g/cm3. Most preferably, the polyethylene has a density of 0.932 to 0.945 g/cm3. The density is ed following the method of standard test ISO 1183 at 23°C.

The polyethylene preferably has a melt index Ml2 of at least 1 dg/min, preferably of at least 1.5 dg/min, more preferably of at least 2 dg/min. It is preferably at most 25 , more ably at most 20 dg/min. Most preferably, the polyethylene has an Ml2 of 1 dg/min to 10 dg/min. The melt flow index Ml2 is measured following the method of standard test ISO 1133 condition D at a temperature of 190°C and a load of 2.16 kg.

Most preferably the polyethylene is prepared with an ethylene bis(4,5,6,7-tetrahydro indenyl) zirconium dichloride metallocene, wherein the polyethylene has a density of 0.930 to 0.950 g/cm3 and a melt index Ml2 of 1 to 10 dg/min.

The polyolefin of layer A may contain additives, in particular additives suitable for rotational moulding, such as, by way of example, processing aids, mould-release agents, anti-slip , y and secondary antioxidants, light stabilizers, anti-UV agents, acid scavengers, flame retardants, s, nanocomposites, lubricants, antistatic additives, nucleating/clarifying agents, antibacterial agents, plastisizers, nts/pigments/dyes and mixtures thereof. Preferably the polyolefin comprises an anti-UV agent. Illustrative ts or colorants include titanium dioxide, carbon black, cobalt aluminum oxides such as cobalt blue, and chromium oxides such as chromium oxide green. Pigments such as ultramarine blue, phthalocyanine blue and iron oxide red are also suitable. Specific examples of additives include lubricants and mould-release agents such as calcium te, zinc te, SHT, antioxidants such as lrgafos 168”", lrganox 1010“", and lrganox 1076T'V', anti-slip agents such as erucamide, light stabilizers such as Cyasorb THT 4611 and 4802, tinuvin 622TM and tinuvin 326“", and nucleating agents such as Milliken HPN20ET'V', or en Hyperform® HPR-803i.

An overview of the additives that can be used in the injection-moulded articles of the present invention may be found in Plastics Additives Handbook, ed. H. Zweifel, 5th edition, 2001, Hanser Publishers.

In a preferred ment of layer A, the PLA s, polyolefin and optional co- or ter- polymer are compounded together according to any known compounding method in the art, e.g. mixer, like a y mixer, or an er, like a twin screw extruder. The extrusion is generally carried out at a temperature below 230°C. 1.2. Pol ester e. . PLA Preferably, the polyester is an aliphatic polyester, although any polyester known in the art can be used. The age of using an aliphatic polyester is that it is prepared from natural renewable ces. The aliphatic ter is preferably selected from polyhydroxyalkanoate (PHA), poly(lactic acid) (PLA), polycaprolactone (PCL), copolyesters and polyesteramides.

The polyester is ably present from 1 to 30 wt% of layer A, more preferably from 2 to 25 wt%, even more preferably from 3 to 20 wt%, yet even more preferably from 4 to 15 wt% and most preferably from 5 to 10 wt% of layer A.

A non-limiting example of a suitable ester includes TritanTM copolyester from Eastman: a copolyester based on the use of 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCD) as a comonomer.

Most preferably, the polyester is a actic acid) (PLA). In particular embodiments, layer A comprises 5 to 30 wt% PLA. Articles wherein the outer layer comprises between 5 and wt% PLA are particularly easy to demould, and show very little deformation, while providing excellent thermal and ical properties.

The poly(lactic acid) (also known as polylactide) is a thermoplastic resin derived from renewable resources.

The poly(lactic acid) also includes copolymers of lactic acid. For instance, copolymers of lactic acid and trimethylene carbonate according to EP application number 11167138 and copolymers of lactic acid and urethanes according to and PCT application number . The introduction of comonomers to PLA increases the ductility (i.e. decreases the brittleness) of the PLA. ably, the PLA used in the rotomoulded e of the invention can be a poly-L- lactide (PLLA), a poly-D-lactide (PDLA) and/or a mixture of PLLA and PDLA. By PLLA, it is meant a polymer in which the majority of the repetitive units are monomers of L-lactide and by PDLA, a polymer in which the majority of the repetitive units are D-lactide monomers. complexes of PLLA and PDLA, as described for example in WO 2010/097463, can also be used. ably, the ctide used is the PLLA.

Preferably, the PLLA or the PDLA respectively have an optical purity (called ic purity) of the L or D isomer, which is higher than 92 wt% of the PLA, preferably higher than 95 wt%. An optical purity from at least 99 wt% is more preferred.

The PLLA used in the invention thus includes a content of D isomer lower than 8 wt%, preferably lower than 5 wt%, more preferably lower or equal to 1 wt% of the PLLA. By analogy, the PDLA includes a content of L isomer lower than 8 wt%, preferably lower than 5 wt%, more preferably lower or equal to 1 wt% of the PDLA.

PLA (PLLA or PDLA) ably has a number e molecular weight (Mn) ranging between 30.000 and 0 g/mol, more preferably between 50.000 and 175.000 g/mol, even more preferably between 70.000 and 150.000 g/mol. The number average molecular weight is measured by chromatography by gel permeation compared to a standard polystyrene in chloroform at 30°C. The ratio of the weight average molecular weight (Mw) to the Mn is generally between 1.2 and 5.0.

The process for preparing PLA is well-known by the person skilled in the art. For example it can be obtained by the process describes in documents WO1998/002480, WO 2010/081887, FR2843390, US5053522, US 5053485 or US5117008.

In an embodiment, the PLA is obtained by polymerizing lactide, in the presence of a suitable catalyst and preferably in the presence of a nd of formula (I), acting as a co-initiator and transfer agent of the polymerization, R1-OH wherein R1 is selected from the group consisting of C1-20alkyl, C5-3oaryl, and C5-3oaryIC1- 20a|kyl, each group being optionally substituted by one or more substituents selected from the group ting of halogen, hydroxyl, and C1-6alkyl. ably, R1 is a group selected from C3_12alkyl, C6_10aryl, and C6_10aryIC3-12alkyl, each group being optionally substituted by one or more tuents each independently selected from the group consisting of halogen, yl, and C1_6alkyl; preferably, R1 is a group selected from C3-12alkyl, C6- 10aryl, and C6-1oary|C3-12alkyl, each group being optionally substituted by one or more substituents each independently selected from the group consisting of halogen, hydroxyl and C1-4alkyl. The l can be a polyol such as diol, triol or higher functionality polyhydric alcohol. The alcohol may be d from biomass such as for instance glycerol or propanediol or any other sugar-based alcohol such as for example itol.

The alcohol can be used alone or in combination with another alcohol.

In an embodiment, non-limiting examples of initiators include 1-octanol, isopropanol, propanediol, trimethylolpropane, 2—butanol, 3-butenol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, 1,7-heptanediol, benzyl alcohol, ophenol,1,4-benzenedimethanol, and (4-trifluoromethyl)benzyl alcohol; preferably, said compound of formula (I) is selected from 1-octanol, isopropanol, and 1,4-butanediol.

The PLA structure can be of the following types in terms of chain termination: R-OH and R-COOH, with R being the PLA chain, obtainable when using monoalcohol as co-initiator, HO-R-OH and HOOC-R-COOH obtainable when using diol as co-initiator, or multiple OH (e.g. 5 ), obtainable when using triol or higher onality polyhydric alcohol as co-initiator, Preferably, the PLA used in layer A has R-OH and , chain termination, and was obtained using a monoalcohol as co-initiator.

Preferably, the PLA used in the layer A of the ion has a crystallinity index (Cl), as measured by XRD, of at least 5%. Preferably the crystallinity index of the PLA is at most 60%.

Preferably, the PLA used in the process of the invention is in the form of particles with an average particle size between 20 um and 2000 um. However n 50 and 1000 pm is preferred and even more preferred is the average particle size of between 100 and 800 pm. In the present invention, by les one understands “grains”, which can be spherical, and/or ovoid forms, or any other shapes or forms. The size ponds to the t dimension of these particles. In the case of spherical particles, the size corresponds to the diameter of these particles. The particles of PLA can be obtained by extrusion of the PLA exiting the polymerization reactor through a die with die gaps having ponding ions.

The PLA defined in the present invention can be in the form of micropellets or powders.

The particles of PLA can be also obtained by grinding/milling pellets of PLA whose dimension is higher than 2000 pm, for example pellets whose dimension lies between 4000 um and 5000 um. Such pellets of PLA can be obtained after polymerization per extrusion while passing the PLA through a die whose openings have corresponding dimension. In this case, the grinding of PLA pellets can be carried out by various types of grinders, such as for example a grinder with a disc, a mill, or an electromagnetic grinder, for example with a piston. Grinding can be done at room temperature or cryogenically, i.e. carried out at a temperature ranging between -10 and -200°C, preferentially between -20 and -100°C. Cryogenic grinding allows in particular to avoid yellowing of the articles obtained and to obtain a highly grinded powder flow. Cryogenic grinding also makes it le to produce a powder t filaments, this being particularly d to the rotomoulding application. Grinding can be carried out under inert atmosphere, i.e. in the absence of oxygen; for example under nitrogen.

After grinding, it is possible to measure and/or modify the granulometry of the PLA by using rotating sieves. To determine the granulometry of the PLA one can use a method of sieving, for example, by using sieves of different mesh sizes, or with a laser Le. a Malvern Mastersizer.

In the present invention, one defines the PLA whose average particle size lies between 20 um and 2000 pm which was obtained from grinding PLA pellets with initial dimensions greater than 2000 um “PLA powder“. The PLA used in the process of the ion can be either in the form of powder, or in the form of micropellets, or in the form of a mixture of powder and micropellets. The powder or micropellets of PLA can be used as they are t the addition of other compounds or they can be mixed with various compounds, loads, agents and/or additives.

Many methods of mixing PLA with such additives can be used in the s of the invention: mixing the additives with PLA in the melt or adding the additives directly to the mould with the PLA powder or micropellets. They can also be mixed with the powder after grinding or with the micropellets before introduction into the rotational mould. They can also be introduced into the PLA still in the molten state obtained ly after rization. Some of these additives can even be added during the polymerization of the PLA. One can also consider the addition of these additives to PLA pellets having a dimension higher than 2.000 um before ng. The powder and ellets of PLA can thus include antioxidants, and light and heat stabilizers, as well as anti-UV agents.

For example, suitable antioxidants include compounds containing phenol functional groups which are sterically hindered in simple or oligomeric form such as x® MD1024 from BASF. One can also use idants called secondaries" such as compounds containing phosphite functional groups such as Ultranox® 626 from Chemtura.

When one of these additives is present, its concentration in the PLA lies between 0.05 wt% and 5 wt%. s, impact resistance modifiers and other additives can also be included.

Fillers are preferentially selected from the group of fibrous compositions such as glass fibres, metal fibres, carbon fibres, ls such as clays, kaolin, or rticles such as carbon nanotubes, and powders such as talc.

Other additives which can be used include, for example, fire retardants, lubricants, plasticizers, anti-static agents, pigments, dyes, surfactants. Among plasticizers, one can in ular select those of the family of citrates, in particular citrate esters like citrate of terbutylene (TBC) or butyrate esters like tri-ethylene glycol di 2-ethyl utyrate or their mixtures. Preferably, TBC is used.

The polyester, in particular PLA, is then blended either in dry form or in the melt with the polyolefin, to create the ition required for layer A.

However, in a preferred embodiment of layer A, the PLA pellets, polyolefin and optional co- or ter-polymer are nded er according to any known compounding method in the art, e.g. mixer, like a Banbury mixer, or an extruder, preferably a twin screw er. The extrusion is generally d out at a temperature below 230°C. 1.3. Optional Co- or Ter-polymer (compatibilising agent) The al co- or ter-polymer comprises ethylene or styrene monomer, an unsaturated anhydride-, epoxide- or carboxylic acid-containing monomer and optionally a (meth)acrylic ester monomer. When present, the co- or ter—polymer acts as a compatibilizer between the polar polyester and the polyolefin. If present the co-or ter-polymer is preferably present from 0.1 to 20 wt%, more preferably from 0.1 to 15 wt%, even more preferably from 0.5 to 10 wt%, most preferably from 1 to 5 wt% of layer A. ably, the optional co- or ter-polymer comprises: a) 50 to 99.9 wt% of ethylene or styrene monomer, preferably 50 to 99.8 wt% , b) 0.1 to 50 wt% of an unsaturated anhydride-, epoxide- or carboxylic acid- containing monomer, c) 0 to 50 wt% of a (meth)acrylic ester monomer , the total sum of components being 100 wt%.

In the embodiment of the co-polymer, it comprises preferably: a) 50 to 99.9 wt% of ethylene or styrene monomer, preferably 50 to 99 wt%, b) 0.1 to 50 wt% of an rated anhydride-, epoxide- or carboxylic acid- containing monomer, preferably 1 to 50 wt% , the total sum of components being 100 wt%.

In the embodiment of the ter-polymer, it comprises preferably: a) 50 to 99.8 wt% of ethylene or styrene monomer, b) 0.1 to 50 wt% of an unsaturated anhydride-, epoxide- or carboxylic acid- containing monomer, c) 0.1 to 50 wt% of a (meth)acrylic ester monomer, the total sum of components being 100 wt%.

In all embodiments of the co- or ter-polymer, the ethylene or styrene monomer (a) is t from 50 to 99.9 wt%, preferably from 50 to 99.8 wt%, more preferably from 60 to 99.5 wt%, even more preferably from 65 to 99 wt%, most preferably from 70 to 98 wt%. In the embodiment of the copolymer, the ethylene or styrene monomer can be present from 90 to 98 wt%.

In all embodiments of the co- or lymer, the unsaturated monomer (b) is preferably selected from an unsaturated anhydride- or epoxide-containing r. More preferably, the rated monomer (b) is selected from a glycidyl (meth)acrylate or maleic anhydride. The unsaturated monomer (b) is preferably present from 0.1 to 40 wt%, more preferably from 0.2 to 30 wt%, even more preferably from 0.3 to 20 wt%, yet even more preferably from 0.3 to 15 wt% and most preferably from 0.3 to 10 wt% of the co- or ter- polymer.

The (meth)acrylic ester monomer (c), if present, is preferably selected from those acrylates which have between 1 and 10 carbon atoms such as for example methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, 2- ethylhexyl (meth)acrylate, or l (meth)acrylate. If present, it ably makes up 0.1 to 50 wt% of the terpolymer, preferably 0.5 to 40 wt%, more ably 1 to 30 wt%, even more preferably 2 to 25 wt% and most preferably 5 to 25 wt% of the terpolymer.

The copolymers of ethylene or styrene monomer and of a yl (meth)acrylate or maleic anhydride can n from 50 to 99 wt% of ethylene or styrene monomer and from 1 to 50 wt% of a glycidyl (meth)acrylate or maleic anhydride, preferably from 90 to 98 wt% WO 34702 of ethylene or styrene monomer and from 2 to 10 wt% of a glycidyl (meth)acrylate or maleic anhydride, the total sum of components being 100 wt%.

The terpolymers of ethylene or styrene monomer, of a glycidyl (meth)acrylate or maleic anhydride and of a (meth)acry|ic ester monomer can contain from 50 to 98.8 wt% of ethylene or styrene r, from 0.2 to 10 wt% of a glycidyl (meth)acrylate or maleic anhydride and from 1 to 50 wt% of a (meth)acry|ic ester monomer, the total sum of components being 100% of the terpolymer. Preferably the terpolymer can contain from 55 to 97.7 wt% of ethylene or styrene monomer, from 0.3 to 8 wt% of a glycidyl acrylate or maleic anhydride, and from 2 to 35 wt% of (meth)acry|ic ester monomer, the total sum of components being 100 wt% of the terpolymer.

Still more preferably, the co- or lymer is selected among copolymers of ethylene and glycidyl methacrylate and terpolymers of ethylene or styrene, acrylic ester monomers and glycidyl methacrylate or maleic anhydride. Among those one can use for example the copolymer of ethylene and glycidyl methacrylate sold under the trademark r®AX 8840 by Arkema France, the terpolymer of ethylene, ethylacrylate and maleic anhydride sold under the denomination Lotader @4700 by Arkema France, as well as the ymer of styrene monomer, acrylic esters and glycidyl methacrylate sold under the trademark Joncryl® by BASF.

In the most preferred embodiment, the co- or ter-polymer is selected from a ymer of ethylene or e monomer, c esters and glycidyl methacrylate. Preferably, the acrylic ester is methylacrylate. An example of such a terpolymer is Lotader®AX8900 sold by Arkema France sing 68 wt% of ethylene monomer, 8 wt% of glycidylmethacrylate and 24 wt% methyl acrylate.

The co- or terpolymer, is then d either in dry form or in the melt with the polyolefin, in particular a polyethylene, and the polyester, in particular PLA, to create the composition required for layer A.

The co- or terpolymer and the polyester can be added one by one to the polyolefin and mixed after each addition or they can be added together and mixed together once.

In a preferred embodiment of layer A, the PLA pellets, polyolefin and optional co- or ter- polymer are compounded together according to any known nding method in the art, e.g. mixer, like a Banbury mixer, or an extruder, preferably a twin screw extruder. The extrusion is generally carried out at a temperature below 230°C.

The composition for layer A can be in powder or micropellet form suitable for rotational moulding. 2 Layer B1 In particular ments, the rotomoulded article comprises one or more layers including a layer A as bed herein and a layer B1, wherein layer B1 comprises 50 to 100 wt% of a polyester, based on the total weight of layer B1, preferably wherein said ter is an aliphatic polyester ed from polyhydroxyalkanoate, poly(lactic acid), polycaprolactone, copolyesters and polyesteramides. The polyester can be present in amounts ranging from 50 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt% or 80 wt% up to 90 wt%, 95 wt%, 96 wt%, 97 wt%, 98 wt%, 99 wt%, 99.4 wt%, 99.5 wt% or 100 wt% of layer B1. In particular, the polyester is ably present from 70 to 95 wt% of layer B1, more preferably 75 to 90 wt%.

The polyester present in layer B1 can be the same as or different from the polyester present in layer A. The description of the polyester present in layer A applies mutatis mutandis to the polyester in layer B1, which can be the same as or different from any polyester present in layer A.

Most preferably, the ter in layer B1 is a poly(lactic acid) (PLA).

The poly(lactic acid) also es copolymers of lactic acid. For instance, copolymers of lactic acid and trimethylene carbonate according to EP application number 38 and copolymers of lactic acid and urethanes according to and PCT application number . The introduction of comonomers to PLA increases the ductility (i.e. decreases the brittleness) of the PLA.

Preferably, the PLA used layer B1 can be a poly-L-lactide (PLLA), a poly-D-lactide (PDLA) and/or a mixture of PLLA and PDLA. By PLLA, it is meant a polymer in which the majority of the repetitive units are monomers of L-lactide and by PDLA, a r in which the majority of the repetitive units are D-lactide monomers. Stereocomplexes of PLLA and PDLA, as described for example in , can also be used. Preferably, the polylactide used is the PLLA.

Preferably, the PLLA or the PDLA respectively have an optical purity (called isomeric purity) of the L or D , which is higher than 92 wt% of the PLA, ably higher than 95 wt%. An optical purity from at least 99 wt% is more preferred.

The PLLA used in layer B1 thus includes a content of D isomer lower than 8 wt%, preferably lower than 5 wt%, more preferably lower or equal to 1 wt% of the PLLA. By analogy, the PDLA includes a content of L isomer lower than 8 wt%, preferably lower than wt%, more preferably lower or equal to 1 wt% of the PDLA.

WO 34702 PLA (PLLA or PDLA) preferably has a number average molecular weight (Mn) ranging between 30.000 and 350.000 g/mol, more preferably between 50.000 and 175.000 g/mol, even more preferably between 70.000 and 150.000 g/mol. The number average molecular weight is measured by chromatography by gel permeation compared to a standard polystyrene in chloroform at 30°C. The ratio of the weight e molecular weight (Mw) to the Mn is generally between 1.2 and 5.0.

The process for preparing PLA is well-known by the person skilled in the art. For example it can be obtained by the process describes in documents WO1998/002480, WO 2010/081887, 390, US5053522, US 5 or US5117008.

In an embodiment, the PLA is obtained by polymerizing lactide, preferably in the ce of a compound of formula (I), acting as a co-initiator and transfer agent of the polymerization, R1-OH wherein R1 is selected from the group consisting of C1-20alkyl, ryl, and C5-30ary|C1- 20a|ky| optionally substituted by one or more substituents selected from the group consisting of halogen, yl, and C1_6alkyl. Preferably, R1 is ed from C3_12alkyl, C6-10ary|, and C6-1oaryIC3-12alkyl, optionally substituted by one or more substituents, each independently selected from the group consisting of halogen, hydroxyl, and C1_6alkyl; preferably, R1 is selected from C3-12a|ky|, C6_10aryl, and C6_10aryIC3_12alkyl, optionally substituted by one or more substituents, each independently selected from the group ting of halogen, hydroxyl and C1-4a|ky|. The alcohol can be a polyol such as dio|, trio| or higher functionality polyhydric alcohol. The alcohol may be derived from biomass such as for instance glycerol or propanediol or any other sugar-based alcohol such as for example erythritol. The alcohol can be used alone or in combination with another l.

In an embodiment, non-limiting examples of initiators include 1-octanol, isopropanol, propanediol, hylolpropane, 2—butanol, nol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, 1,7-heptanediol, benzyl alcohol, 4-bromophenol,1,4-benzenedimethanol, and (4-trifluoromethy|)benzy| l; preferably, said compound of formula (I) is selected from 1-octanol, isopropanol, and tanediol.

The PLA structure can be of the following types in terms of chain termination: R-OH and R-COOH, with R being the PLA chain, obtainable when using monoalcohol as co-initiator, 2012/067529 HO-R-OH and HOOC-R-COOH obtainable when using diol as co-initiator, or multiple OH (e.g. 5 ), obtainable when using triol or higher functionality polyhydric alcohol as co-initiator.

Preferably, the PLA used in layer A has R-OH and R-COOH, chain termination, and was obtained using a monoalcohol as co-initiator.

Preferably, the PLA used in the layer B1 of the invention has a llinity index (Cl), as measured by XRD, of at least 5%. Preferably the llinity index of the PLA is at most 60%.

Preferably, the PLA used in layer B1 is in the form of les with an average particle size between 20 um and 2000 um. However between 50 and 1000 pm is preferred and even more preferred is the average particle size of between 100 and 800 pm. In the present invention, by particles one understands “grains”, which can be spherical and/or ovoid forms, or can be of any other shapes or forms. The size corresponds to the longest dimension of these particles. In the case of spherical particles, the size ponds to the diameter of these particles. The particles of PLA can be ed by extrusion of the PLA exiting the polymerization reactor through a die with die gaps having corresponding dimensions.

The PLA used in layer B1 can be in the form of micropellets or powders. The particles of PLA can be also obtained by grinding/milling pellets of PLA whose dimension is higher than 2000 pm, for example pellets whose dimension lies n 4000 um and 5000 um.

Such pellets of PLA can be obtained after polymerization per extrusion while g the PLA through a die whose openings have corresponding ion. In this case, the grinding of PLA pellets can be carried out by s types of grinders, such as for example a grinder with a disc, a mill, or an omagnetic grinder, for example with a piston. Grinding can be done at room temperature or cryogenically, i.e. carried out at a temperature ranging between -10 and -200°C, preferentially between -20 and -100°C.

Cryogenic grinding allows in ular to avoid yellowing of the articles obtained and to obtain a highly grinded powder flow. Cryogenic grinding also makes it possible to produce a powder without filaments, this being particularly adapted to the rotomoulding application.

Grinding can be carried out under inert atmosphere, i.e. in the e of oxygen; for example under nitrogen.

After grinding, it is possible to measure and/or modify the granulometry of the PLA by using rotating sieves. To determine the granulometry of the PLA one can use a method of sieving, for example, by using sieves of different mesh sizes, or with a laser Le. a Malvern Mastersizer.

In the present invention, one defines the PLA whose average particle size lies between 20 um and 2000 pm which was obtained from grinding PLA pellets with initial dimensions greater than 2000 um “PLA powder“. The PLA used in layer B1 can be either in the form of powder, or in the form of micropellets, or in the form of a e of powder and micropellets. The powder or micropellets of PLA can be used as they are without the addition of other nds or they can be mixed with various compounds, loads, agents and/or additives, as described for the PLA of layer A.

In particular ments, layer B1 comprises 50 to 99.9 wt% of the polyester and from 0.1 to 10 wt% of a co- or ter-polymer comprising a) 50 to 99.9 wt% of an ethylene or a styrene monomer, b) 0.1 to 50 wt% of an unsaturated anhydride-, epoxide- or carboxylic acid-containing monomer, and c) 0 to 50 wt%, preferably 0.1 to 30 wt%, (meth)acrylic ester monomer.

The co- or ter-polymer can be the same as or different from the co- or ter-polymer present in layer A. The description of the co- or ter-polymer present in layer A s mutatis mutandis to the co- or ter-polymer in layer B1, which can be the same as or different from any co- or lymer present in layer A.

The ition for layer B1 can be in powder or micropellet form, or a blend of both, suitable for rotational moulding.

Layer B1 is preferably adjacent to layer A. The polymer compositions of layer A and B1 typically exhibit an excellent adherence between the two rotomoulded layers.

In particular embodiments, the rotomoulded article ses a layer A and a layer B1.

In a particular embodiment, the rotomoulded article may comprise two layers: layer A and layer B1, n: 0 layer A is the outer layer, 0 layer B1 is adjacent to layer A, and comprises from 50 wt% to 100 wt% of a polyester, preferably from 80 wt% to 100 wt%, more preferably from 95 wt% to 100 wt%.

In certain embodiments, layer B1 is the inner layer. This is particularly advantageous when it is envisaged to fill the rotomoulded e with a polyurethane. Although the inventors have found that ethane adhere well particularly well on layer A, the increased polyester content of layer B1 allows for an enhanced foam adherence. Thus, in such embodiments, layer A provides the required strength and protection against deformation of the e, while layer B1 provides an enhanced nce to a polyurethane, such as a polyurethane foam. 3 LayerB 3.1 Polyolefin Layer B is preferably adjacent to layer A.

The polyolefin is present from 50, 60 or 70 up to 100 wt% of layer B, or up to 99.8, 99, 97.5, 97, or 95 wt% of layer B.

The polyolefin can be the same as or different from the efin t in layer A.

The polyolefin can be selected from polyethylene, polypropylene, polybutene or polyhexene.

Preferably, the polyolefin is polyethylene. The description of polyethylene present in layer A applies mutatis mutandis to the polyethylene in layer B, which can be the same as or different from any polyethylene present in layer A.

The composition for layer B can be in powder or micropellet form, suitable for rotational moulding. When al chemical blowing agent is present and micropellets are used, the polyolefin and al blowing agent are preferably compounded together instead of dry blended. 3.2 The polyolefin optionally foamed — chemical blowing agents Optionally, layer B is a foamed polyolefin layer. In order to foam efin a chemical blowing agent can be included into layer B, which causes the polyolefin to foam under the riate conditions in the presence of a blowing gas in the mould during rotational moulding. The chemical blowing step generally fulfils several requirements: -the decomposition temperature range of the blowing agent is compatible with the processing temperature of the polyolefin; -the liberation of the blowing gas occurs within a defined temperature range of about 10 °C and is controllable during the process; -the osition is not autocatalyzed in order to avoid overheating; WO 34702 -the blowing gas is chemically inert, such as preferably nitrogen, carbon dioxide and water; -the chemical blowing agent is homogeneously and easily incorporated in and ible with polyethylene.

During the foaming s, at elevated temperatures, chemical blowing agents undergo chemical reactions that liberate gas, typically N2, CO, C02 and NH3 and water.

The chemical agents that can be used in the present invention can function according to three main ses: Irreversible on: AB --> C + gas. They can be selected from the group consisting of azo compounds, hydrazine derivatives, semicarbazides, tetrazoles and nitroso compounds.

Equilibrium reactions: AB <---> C + gas. They can be selected from the group consisting of bicarbonates and carbonates.

Combination of compounds that liberate gases as a result of their chemical interactions: A + BG --> AB + gas.

The chemical blowing agents can be: Exothermic, such as for example azodicarbonamide (AZ) or 4,4'-oxy- bis(benzenesulfonylhydrazide) (OB); or Endothermic, such as for example sodium bicarbonate (SB).

Suitable chemical blowing agents include: Organic al blowing agents: Azo compounds such as for e azodicarbonamide decompose at a temperature range of from 160 to 215 °C and liberate about 220 ml/g of gas, mostly N2, CO, C02, NH3 and water.

Hydrazides such as for example or 4,4'-oxy-bis(benzenesulfonylhydrazide) (from example Genitron®OB from LANXESS). lt decomposes at a temperature range of from 140 to 160 °C and liberates 120 to 140 ml/g of gas, mostly N2 and H20. This type of agent is ularly preferred as it is exothermic and releases only neutral gases.

Other examples include modified arbonamide, i.e., azodicarbonamide modified with zinc oxide, calcium carbonate or the like to lower the decomposition WO 34702 temperature, 5-phenyltetrazole, dinitrosopentamethylene tetramine, isobutyronitrile, diazoaminobenzene, oxybis(benzenesulfonylhydrazide) and the like. nic chemical blowing : Carbonates such as for example sodium bicarbonate Nchog. lt decomposes at a temperature range of from 150 to 230 °C and liberates 140 to 230 ml/g of gas, mostly 002 and H20.

Other examples include sodium borohydride, ammonium carbonate, and modified sodium bicarbonate, i.e. sodium bicarbonate modified with a proton donor such as citric acid, and the like.

The amount of blowing agent added to the polyolefin is of at least 0.2 wt% based on the total weight of layer B, preferably of at least 1 wt%. It is of at most 5 wt%, preferably of at most 3 wt%. The most preferred amount is of about 2.5 wt%. The al blowing agent totally oses upon foaming. 3.3 Preparing the optionally foamed polyolefin layer B The foamed polyolefin layer is prepared by rd techniques with one or more chemical blowing agent(s). The chemical blowing agent is incorporated into the polyolefin to form a blend. The blend may be prepared by extruding the polyolefin either with a masterbatch comprising the chemical blowing agent or directly with the blowing agent. In both cases, the extrusion temperature of must be kept above the melt temperature of the polyolefin but below the decomposition temperature range of the chemical blowing s). The melt is passed through a suitable die, such as used with a pelletizer, to obtain the ized resin.

Alternatively, and preferably, the polyolefin is dry blended with the al blowing agent(s) and introduced directly into the mould during the rotomoulding cycle. Dry blending is favoured over compounding the chemical blowing agent with the polyolefin, because the mixing has to be carried out below the decomposition temperature of the chemical blowing agent.

While it is not necessary, additives which function to control or modify foam cell size or foam density or modify/control the activator temperature or rate of decomposition of the al blowing agent may also be included in the polyolefin. Useful additives of this type include calcium carbonate, titanium dioxide, zinc oxide, talc, calcium stearate, nanocomposites and the like. When present, the amount of these ves typically ranges from about 0.01 to about 1 percent by weight, based on the weight of the foamed polyolefin layer.

The preferred density of the foamed layer is between 100 to 200 kg/m3.

The preferred thickness of the foamed layer is from 10 to 500 mm, preferably 100 to 200 mm, according to the desired use of the u|ded article. 3.4 Further optional components In another embodiment, layer B may also comprise other ents besides the polyolefin. For example, it may comprise: Ofrom 50 to 99.5 wt%, preferably 60 to 99.4 wt%, of the efin, which can be different from the polyolefin of layer A, o from 0 to 50 wt%, preferably 0.5 to 50 wt%, more preferably 0.5 to 30 wt% , of a polyester (preferably PLA), which can be ent from the polyester of layer A, o from 0 to 20 wt%, preferably 0.1 to 15 wt%, of a co- or ter-polymer, which can be different from the co- or ter-polymer of layer A, comprising: a) 50 to 99.9 wt% of an ethylene or a e r, b) 0.1 to 50 wt% of an unsaturated anhydride-, epoxide- or carboxylic acid- containing monomer, c) 0 to 50 wt% (meth)acry|ic ester monomer.

The ption of the polyester (section 1.2 above) and the co- or ter-polymer (section 1.3 above) present in layer A applies mutatis mutandis to layer B. The optional polyester (preferably PLA) and the optional co- or ter-polymer can be the same as or different from those present in layer A.

Thus, layer B can be the same as or different from layer A. 4 LayerC 4.1 Polyolefin Layer C is preferably nt to layer B. In a particular embodiment, |ayer C is adjacent to layer B, which is adjacent to layer A. Layer A is preferably the outer lay in this case, layer B in the intermediate layer and layer C the inner layer. Layer C can be the same as or different from layer A.

The po|yo|efin is present from 50, 60 or 70 up to 100 wt% of layer C, or up to 99.8, 99, 97.5, 97, or 95 wt% of layer B.

The polyolefin can be the same as or different form the polyolefin present in layer A.

The polyolefin can be selected from polyethylene, polypropylene, polybutene or xene.

Preferably, the efin is hylene. The description of polyethylene t in layer A applies mutatis mutandis to the polyethylene in layer C, which can be the same as or different from any polyethylene present in layer A.

The composition for layer C can be in powder or micropellet form, suitable for rotational moulding. 4.2 Further optional components In another embodiment, particularly when layer C is the inner, layer C may also comprise other components besides the polyolefin. For example, it may comprise: Ofrom 50 to 99.5 wt%, preferably 60 to 99.4 wt%, of the efin, which can be different from the polyolefin of layer A, o from 0 to 50 wt%, preferably 0.5 to 50 wt%, more preferably 0.5 to 30 wt% , of a polyester (preferably PLA), which can be different from the polyester of layer A, o from 0 to 20 wt%, preferably 0.1 to 15 wt%, of a co- or ter—polymer, which can be different from the co- or ter-polymer of layer A, comprising: a) 50 to 99.9 wt% of an ethylene or a styrene monomer b) 0.1 to 50 wt% of an unsaturated anhydride-, epoxide- or carboxylic acid- containing monomer c) 0 to 50 wt% (meth)acrylic ester monomer The description of the polyester (section 1.2 above) and the co- or ter—polymer (section 1.3 above) present in layer A applies mutatis mutandis to layer C. The optional ter (preferably PLA) and the optional co- or ter-polymer can be the same as or different from those present in layer A. Thus, layer C can be the same as or different from layer A.

The rotomoulding process The rotomoulded article according to the invention ses at least one layer, namely layer A. The article can be a mono-layered article only having layer A, or it can be a bi- layered or tri-layered rotomoulded article.

According to the invention, the article may further comprise a layer B1 and/or B, preferably adjacent to layer A. In addition, a third layer, layer C, can be present, preferably adjacent to layer B.

The onal moulding is a process nown to the person skilled in the art. The various processes of rotational moulding usually comprise the following stages: a) loading of the mould, b) on of the mould, c) heating of the mould, d) cooling and e) release from the mould.

The mould can be made of any material known in the art for such a purpose. For example, the mould can be an aluminum mould or a Teflon mould. Teflon moulds are preferred to avoid any sticking to the mould due to the decreased shrinkage and warpage according to the article of the invention.

The rotation of the mould is generally carried out around two perpendicular axes.

The quantity of powder and/or of micropellets introduced into the mould depends on the size of the article and on the desired wall thickness.

The heating step (c) of the mould occurs simultaneously with the rotation of the mould in step (b).

In one embodiment, the heating step can be carried out in an oven or by electric heating ts. In another preferred embodiment g can be carried out with a mould heated by an oil-filled heating jacket, as in for example, the do® ulding machine from Persico®. The heating temperature of the oven, ic heating elements or oil can vary from 150 to 350°C. One generally uses a temperature of at least of 10°C higher, preferentially at least of 20°C higher, more preferentially at least of 30°C higher compared to the melting point of the layer that one wishes to mould. A heating ature ranging from 180 and 270°C is preferably used. In another embodiment, heating can also be carried out by microwaves.

The duration of the moulding varies according to dimensions and the ess of rotomoulded article, it can be range from 5 to 600 minutes.

The duration and the time of cooling step depends on the installation, on the dimensions of the article to be moulded and of the type of article which one wishes to obtain. As 2012/067529 mentioned previously, it is possible to cool the mould and/or the article contained in the mould. To cool the mould from the outside, one can use air at room temperature, water between 5 and 25°C or oil between 5 and 80°C. To cool the article from the inside of the mould, one can inject air and/or inert gas such as nitrogen and/or spray water (like a mist) within the interior of the mould, for example at a temperature of 25°C. The time of cooling lly varies between 5 and 500 minutes ing on the thickness of the rotomoulded article and the process used for cooling. When the article has a thickness of more than 10 mm, the mould should preferably be cooled from both the inside of the mould and the outside, preferably using air or inert gas such as nitrogen or a spray of water (mist).

According to a mode of realization, the cooling of the mould and/or article obtained are done in just one step until a temperature ranging between room temperature and a temperature lower than 100°C is obtained. According to this mode of realization, cooling in this way results in a crystalline ulded object.

Thereafter, the article is released from the mould. Release of the article from the mould is generally carried out when the article has sufficient rigidity. The release from the mould is generally done at a temperature lower than 100°C.

The rotational moulding can be carried out under inert gas in the absence of oxygen. In order to do so, one can for example add into the mould a compound which liberates carbon dioxide, such as dry ice. This can be for example together with the powder or pellets of the different components. Dry ice tes carbon e during the heating and rotating steps of the moulding process. One can also purge the mould with an inert gas, such as nitrogen, by injecting en after closing the mould.

The walls of the articles can comprise one or more successive layers, at least having layer A as claimed. It is thus possible to manufacture articles with walls comprising for es two or three layers e.g. optionally having a layer B1, and/or a layer B and/or a layer C. In one embodiment, layer B can be .

In a particular ment, layer A is the outer layer, layer B1 is the inner layer.

In a particular embodiment, layer A is the outer layer, layer B is the intermediate layer and layer B1 is the inner layer.

In a particular embodiment, layer A is the outer layer, layer B is the intermediate layer and layer C is the inner layer. In this particular ment, layer C may further comprise a polyester and optionally a co- or terpolymer according to the same definitions as in layer A.

Layer C can be same as or different from layer A.

In another embodiment, layer A is the intermediate layer adjacent to layers B and C, wherein layers B and C are either the outer or inner layers respectively. Layers B and C can be same or different in this embodiment.

There are several known methods to manufacture multilayered rotomoulded articles: by manual introduction of material during the rotomoulding cycle, or by the use of a drop-box, or by a one-shot system wherein each layer has a different melting temperature and are introduced into the mould together.

Manual addition involves moving the mould from the oven, removing a vent tube or plug that creates an opening in the part and adding more material using a funnel or wand. This ion must be repeated for each additional layer.

A drop-box typically contains the al for a particular layer and it is an insulated container that holds material until it is ed at the appropriate time during the cycle.

The signal for release of material is usually transmitted as a pressure pulse via the airline through the arm of the machine. The insulation is kept cool to prevent the material inside the box from melting.

In either of these two methods, there are two factors to consider, which are in fact known to the skilled person in multilayered rotomoulding applications: i. the ature at which the subsequent layer is added for determining the wall thickness of the previous skin formed and how well the two layers may be bound together; ii. the time elapsed before addition of the uent layer of material to avoid sag.

It is possible to control these by lowering the melt index of the first layer and/or by reducing the injection temperature of the next layer, and/or by cooling the mould slightly before injection of the next layer.

The cycle time necessary to produce multilayer rotomoulded articles depends upon the number of layers and upon the mass injected for each layer.

The present ion also discloses a method for rotomoulding the articles ing to the invention for one or more layers comprising the steps of (in no particular order) according to the process known to the skilled : a) feeding the composition for layer A) into a mould; b) g the filled mould in pre-heated oven; c) rotating the filled mould about two perpendicular axes; d) optionally feeding the composition for layer B1, followed by repeating steps (b) and (c); e) optionally feeding the composition for layer B, optionally with a chemical blowing agent and blowing gas to prepare a foamed layer B, followed by ing steps (b) and (c); f) optionally feeding the composition for layer C), followed by ing steps (b) and (c); g) optionally g desired additional layers, each addition followed by repeating steps (b) and (c), h) cooling and retrieving the rotomoulded article.

Preferably, the process is d out in the order described.

Alternatively, the optional chemical blowing agent for creating a foamed layer B can be introduced during the rotomoulding cycle by a Teflon tube.

The first key point in the process is the time at which the temperature inside the mould reaches the melting temperature of the composition for layer A. ition for layer B1 (if adjacent to layer A) comprising polyester can be injected as soon as orjust before that first melting temperature is reached.

Composition for layer B (if adjacent to layer A) sing polyolefin (and optionally a chemical blowing agent) is ed as soon as orjust before that first melting temperature is reached. The composition for layer B is preferably injected at an internal air temperature ed between 125 and 160°C.

The second key point in the process is the time at which the temperature inside the mould reaches the melting temperature of ition for layer B. Composition for layer C is ed as soon as or just before that second melting temperature is reached. The composition for layer C is ed at an internal air temperature situated n 125 and 160°C. The internal air temperature must be compatible with the temperature and is preferably of at most 170°C during the whole cycle time.

The articles obtained by rotational moulding are generally hollow parts without any welding lines, such as for tanks, drums, containers, vats, jerrycans, cans, cisterns, boxes, bumpers, furniture (bath tubs), car parts such as car doors, car bodies and car seats, nautical and aquatic equipment, buoys, floats, boards, planks and joints. The rotomoulded article is preferably selected from the group comprising car parts. Among the car parts, one can for example quote the car body and car door and interior components such as the instrument panel and door handles.

These articles can have one or more openings and/or inserts of plastic or metal and/or “kiss offs” which are reinforcing junctions or bridges between two surfaces within the article.

Articles obtained by the rotational moulding s according to the invention do not have a point of weakness. They show homogeneous characteristics, such as for example a uniform ess of the walls as well as a good surface aspects both internally and internally and externally, without any deformation, bubble or other defects. In addition, the compositions for use in the present process do not t any sagging behavior during the rotomoulding process.

In particular, the articles obtained have a very little shrinkage and warpage. In addition, the presence of the co- or terpolymer (compatibilising agent) increases the impact strength of the article.

Note, also when layer A is the outer layer they can be painted very easily because of the high surface tension due to the presence of polyester. 6 Filling with ethane foam The articles obtained by rotational moulding are lly hollow parts without any welding lines. Being hollow the rotomoulded articles according the present invention typically se one or more cavities. In an embodiment, enhanced insulation properties or ural properties can be ed by filling these cavities with a polyurethane (PU), such as a ethane foam.

The inventors surprisingly found that for the rotomoulded articles according to the present invention the adherence between the article inner wall and a PU foam is excellent.

Accordingly, in particular embodiments, the present rotomoulded articles comprise at least one cavity which comprises, preferably which is filled with a polyurethane, such as a ethane foam.

PU foams can greatly enhance the structural and insulating properties of the rotomoulded article, without adding much weight to the article. The PU foam may be a rigid, igid, or soft PU foam. Rigid PU foams are preferred to enhance the structural properties of the rotomoulded article. The softness and elastic ties of the polyurethane foams depend on the choice of the polyol and isocyanate monomers, as the polyol monomers typically provide soft domains, and the isocyanate monomers form harder domains.

The type of PU polymer comprised by the PU foam is not critical to the present invention.

The PU polymer may be made by introduction into the rotomoulded article of a PU forming composition as described below.

The filling with PU foam can be obtained by introducing a PU forming composition into one or more cavities of the rotomoulded article.

In general, such a PU g composition comprises : at least one isocyanate compound, hereinafter also referred to as anate monomer”; and at least one polyol, hereinafter also referred to as “polyol r”.

Suitable isocyanate monomers include polyisocyanates, such as diisocyanates and/or triisocyanates. The polyisocyanates may be aliphatic, araliphatic and/or aromatic polyisocyanates, typically of the type RZ-(NCO)X with x being at least 2 and R2 being an aromatic, aliphatic or combined aromatic/aliphatic group. Examples of R2 are diphenylmethane, toluene, ohexylmethane, thylene, or groups providing a similar polyisocyanate.

Non-limiting examples of suitable polyisocyanates are diphenylmethane diisocyanate (MDI) — type isocyanates in the form of its 2,4'-, 2,2'- and 4,4'-isomers and mixtures thereof (also referred to as pure MDI), the mixtures of diphenylmethane diisocyanates (MDI) and oligomers f (known in the art as "crude" or polymeric MDI ), and reaction products of polyisocyanates (e.g. polyisocyanates as set out above), with ents containing nate-reactive hydrogen atoms forming polymeric ocyanates or so- called prepolymers. Other examples are tolylene diisocyanate (also known as e diisocyanate, and referred to as TDI), such as 2,4 TDI and 2,6 TDI in any suitable isomer mixture, hexamethylene diisocyanate (HMDI or HDI), isophorone diisocyanate (lPDl), butylene diisocyanate, trimethylhexamethylene diisocyanate, di(isocyanatocyclohexyl)methane, e.g. 4,4’-diisocyanatodicyclohexylmethane (H12MDI), isocyanatomethyl-1,8—octane diisocyanate and ethylxylene diisocyanate (TMXDI), 1,5-naphtalenediisocyanate (N DI), p-phenylenediisocyanate (PPDI), 1,4- cyclohexanediisocyanate (CDI), tolidine diisocyanate (TODI), any suitable mixture of these polyisocyanates, and any suitable mixture of one or more of these polyisocyanates with MDI-type polyisocyanates.

The polyurethane is generally prepared by reacting an isocyanate monomer with one or more polyol monomers. Suitable polyol monomers e a hydroxyl ated polyester (polyester s), a hydroxyl terminated polyether (polyether polyols), a hydroxyl terminated polycarbonate, or a mixture thereof. In particular embodiments, the polyol monomers comprise one or more monomers selected from the group consisting of a polyether diol, a polyether triol, a polyester diol, and a polyester triol.

The polyester polyols may be generally a linear polyester, and may have an average molecular weight (Mn) of from about 500 to 10000. The lar weight may be determined by assay of the terminal functional groups and is related to the number average molecular weight. The polymers can be produced by (1) an esterification on of one or more glycols with one or more oxylic acids or anhydrides or (2) by transesterification reaction, i.e. the reaction of one or more glycols with esters of dicarboxylic acids. Mole ratios generally in excess of more than one mole of glycol to acid are preferred so as to obtain linear chains having a preponderance of terminal hydroxyl groups. Suitable polyester intermediates also include various lactones such as polycaprolactone typically made from caprolactone and a bifunctional initiator such as diethylene glycol. The dicarboxylic acids of the desired polyester can be aliphatic, cycloaliphatic, aromatic, or combinations thereof. Suitable dicarboxylic acids which can be used alone or in mixtures generally have a total of from 4 to 15 carbon atoms and include: succinic, glutaric, adipic, c, suberic, azelaic, sebacic, dodecanedioic, isophthalic, terephthalic, cyclohexane dicarboxylic, and the like. Anhydrides of the above dicarboxylic acids such as phthalic ide, tetrahydrophthalic anhydride, or the like, can also be used. The glycols which are reacted to form a desirable polyester intermediate can be tic, aromatic, or combinations thereof, and have a total of from 2 to 12 carbon atoms, and e ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4- diol, 1,5-pentanediol, 1,6-hexanediol, 2,2-dimethyl-1,3-propanediol, 1,4- exanedimethanol, thylene glycol, dodecamethylene glycol, and the like.

Polyether polyols may be derived from a diol or polyol having a total of from 2 to 15 carbon atoms, preferably an alkyl diol or glycol which is reacted with an ether comprising an alkylene oxide having from 2 to 6 carbon atoms, typically ethylene oxide or propylene oxide or es thereof. For example, yl functional polyether can be produced by first reacting ene glycol with propylene oxide followed by subsequent reaction with ethylene oxide. Primary hydroxyl groups resulting from ethylene oxide are more reactive than secondary hydroxyl groups and thus are red. Useful commercial polyether polyols include thylene glycol) comprising ne oxide reacted with ethylene glycol, ropylene glycol) comprising propylene oxide reacted with propylene glycol, poly(tetramethyl glycol) (PTMG) comprising water reacted with tetrahydrofuran (THF). her polyols further include polyamide adducts of an alkylene oxide and can include, for example, ethylenediamine adduct comprising the reaction product of ethylenediamine and propylene oxide, diethylenetriamine adduct sing the reaction product of diethylenetriamine with propylene oxide, and similar polyamide type polyether polyols.

Copolyethers can also be ed in the current invention. Typical copolyethers include the reaction product of glycerol and ethylene oxide or glycerol and propylene oxide.

Hydroxyl ated polycarbonate intermediates can be prepared by ng a glycol with a carbonate. US 4131731 is hereby incorporated by reference for its disclosure of hydroxyl terminated polycarbonates and their preparation. Such polycarbonates are linear and have terminal hydroxyl groups with essential exclusion of other terminal groups. The essential reactants are glycols and carbonates. Suitable s are selected from cycloaliphatic and aliphatic diols containing 4 to 40, and preferably 4 to 12 carbon atoms, and from yalkylene glycols containing 2 to 20 alkoxy groups per le with each alkoxy group containing 2 to 4 carbon atoms. Diols le for use in the present ion include aliphatic diols containing 4 to 12 carbon atoms such as butanediol-1,4, pentanediol-1,4, neopentyl glycol, hexanediol-1,6, 2,2,4-trimethylhexanedion-1,6, decanediol-1,10, hydrogenated dilinoleylglycol, hydrogenated diolelylglycol; and cycloaliphatic diols such as cyclohexanediol-1,3, dimethylolcyclohexane-1,4, cyclohexanediol-1,4, dimethylolcyclohexane-1,3, 1,4-endomethylenehydroxy hydroxymethyl cyclohexane, and polyalkylene glycols. The diols used in the on may be a single diol or a mixture of diols ing on the properties desired in the finished product.

Non-limiting examples of suitable carbonates for use herein include ne carbonate, trimethylene carbonate, tetramethylene carbonate, 1,2-propylene carbonate, 1,2-butylene carbonate, tylene carbonate, 1,2-ethylene carbonate, ntylene carbonate, 1,4- pentylene carbonate, 2,3-pentylene carbonate and 2,4-pentylene carbonate.

Also suitable herein are dialkylcarbonates, cycloaliphatic ates, and diarylcarbonates. The dialkylcarbonates can contain 2 to 5 carbon atoms in each alkyl group and specific examples thereof are diethylcarbonate and dipropylcarbonate. liphatic carbonates, especially dicycloaliphatic carbonates, can contain 4 to 7 carbon atoms in each cyclic structure, and there can be one or two of such structures.

When one group is cycloaliphatic, the other can be either alkyl or aryl. On the other hand, if one group is aryl, the other can be alkyl or cycloaliphatic. Preferred examples of diarylcarbonates, which can contain 6 to 20 carbon atoms in each aryl group, are diphenylcarbonate, ditolylcarbonate and dinaphthylcarbonate.

The reaction is carried out by reacting a glycol with a carbonate, preferably an alkylene carbonate in the molar range of 10:1 to 1:10, but preferably 3:1 to 1:3 at a temperature of 100°C to 300°C and at a pressure in the range of 0.1 to 300 mm Hg in the presence or e of an ester interchange catalyst, while removing low boiling glycols by lation.

In particular embodiments, the PU forming composition can comprises one or more polyether diols or triols. The choice of polyol monomer may depend on the required specifications of the rotomoulded, PU filled article. For example, polyethers typically provide a better microbial and fungal resistance, are easier to process (due to the lower viscosity), and have a lower cost, compared to polyesters. On the other hand, polyesters may provide a better wear resistance; load bearing properties; heat aging properties; reactivity; and oxygen, ozone and UV stability. Polyesters may further swell less in oils, grease and solvents.

The PU forming composition may further comprise one or more chain extenders, all of which are well known to those skilled in the art. Non-limiting es of suitable chain extenders are lower tic or short chain glycols having from about 2 to about 10 carbon atoms and include, for instance, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,3-butanediol, 1,5-pentanediol, 1,4-cyclohexanedimethanol, hydroquinone roxyethyl)ether, neopentylglycol, and the like.

In ular embodiments, the PU ation can comprise one or more catalysts, for example ed from the group consisting of a tertiary amine, such as bis-(2- dimethylaminoethyl)ether, N-ethylmorpholine, triethylenediamine, dimethylcyclohexylamine, or dimethylethanolamine; and an organotin compound, such as dibutyltin dilaurate, dioctyltin tide, or dibutyltin oxide.

In certain embodiments, the PU forming composition may comprises one or more mineral fillers such as certain oxides, carbonates, silicates, borates, tes, mixed oxide hydroxides, oxide hydroxide carbonates, hydroxide silicates, or hydroxide borates, or a mixture of these substances. By way of example, use may be made of calcium oxide, aluminum oxide, manganese oxide, tin oxide, te, dihydrotalcite, hydrocalumite, or calcium carbonate.

In n ments, the PU g composition may se one or more foam stabilizers. Foam stabilizers are substances which promote the formation of a regular cell structure during foaming. Non-limiting examples of foam stabilizers are silicone- comprising foam stabilizers such as siloxane-oxalkylene copolymers or other 2012/067529 organopolysiloxanes, alkoxylation products of fatty alcohols, oxo alcohols, fatty amines, alkylphenols, dialkylphenols, alkylcresols, alkylresorcinol, ol, alkylnaphthol, naphthylamine, aniline, alkylaniline, ine, bisphenol A, alkylated bisphenol A, and polyvinyl alcohol.

The PU forming composition can further se one or more solvents, as known by the person skilled in the art.

The polyurethane is generally made from the abovementioned polyol monomer, preferably polyether, which is further reacted with an isocyanate monomer, preferably a diisocyanate, along with one or more additives selected from a chain extender, a catalyst, a foam stabilizer, a filler, a dye, a pigment, a flame retarder, an antioxidant, a fungicide, and a biocide.

Foams can be made by using chemical or inert blowing agents while ting above reactions, or by using a gas in order to create a froth during these reactions. A particularly suitable chemical blowing agent is water. Water can react with isocyanate functional groups, thereby releasing carbon dioxide, which can act as blowing gas. Accordingly, in particular embodiments, the PU forming composition comprises water.

The amount of blowing agent present in the PU forming mixture influences the density of the PU foam formed by the PU forming composition. 7 Coating of the rotomoulded article The inventors have found that the rotomoulded articles of the invention are easy to coat or paint. Surprisingly, the inventors further found that the rotomoulded articles can be coated as soon as the articles are demoulded, without any surface treatment.

The rotomoulded articles described herein may be coated for various es, for example for aesthetic s, for ing fire-retardant properties, for ing hydrophilic or hobic properties, for protecting the surface against UV-light, scratching, heat, etc.

In particular embodiments, the rotomoulded article described herein is painted. Suitable paints which provide good results include polyurethane-based , epoxy based paints, and ellulose-based paints, acrylic , and alkyd paints. In preferred embodiments, the paint is selected from the group consisting of polyurethane-based paints, epoxy based paints, and nitrocellulose-based paints. The adherence of the paint was tested via a cross-cut test according to NF EN ISO 2409.

In particular embodiments, the article is painted or coated with a flame-retardant substance, for example a flame-retardant paint or varnish. In particular embodiments, the articles may comprise a flame-retardant coating, wherein said coating preferably comprises one or more intumescent substances, i.e. substances that swell as a result of heat exposure, thus increasing in volume and decreasing in density, y ing a passive fire protection. Examples of intumescents include sodium silicates and materials which comprise a significant amount of hydrates.

In certain embodiments, the rotomoulded article is coated with a topcoat. miting examples of topcoat materials include a polyester resin, an amino resin, or isophthalic celerated unsaturated polyester such as r iso PA F from CCP composites, or combinations thereof. Such articles may be car parts, boat parts, or the like.

The coatings described herein may be applied by any suitable coating technique, including but not limited to spray coating, and dip coating.

EXAMPLES The following examples illustrate the invention, but by no means intend to limit the scope of the invention. ical methods 1. Determination of the optical purity of the PLA In the examples which follow, the determination of the optical or ic purity of the PLA is done by the enzymatic method. The principle of the method is the following: The ions Lactate and D-Lactate are oxidized in pyruvate respectively by the enzymes ate dehydrogenase and D-lactate dehydrogenase using the nicotinamide adenine dinucleotide (NAD) as the coenzyme. To force the reaction in the direction of pyruvate formation, it is ary to trap this nd by reaction with ine. The optical density increase to 340 Nm is proportional to the quantity of L-lactate or D-lactate present in the sample.

The samples of PLA were prepared by mixing 25 ml of sodium hydroxide (1mol/L) with 0.6 g of PLA. The solution was refluxed for 8 hours and then cooled. The on was then lized to pH 7 using a hydrochloric acid solution (1mol/L), then sufficient deionized water was added to obtain 200 ml of on.

The samples were then analyzed on a Vital Scientific Selectra Junior analyzer used for the determination of L isomer of the poly-L-lactide, the box entitled “L-lactic acid 5260” marketed by the company Scil was used and for the determination in D isomer of the poly- D-lactide, the box entitled “L-lactic acid 5240” marketed by the company Scil was used.

During the analysis, a reactive blank and a calibration solution called “Scil 5460” were used. 2. Determination of the molecular weight of the PLA In the examples which , the ement of the lar weight is carried out at °C by using a liquid chromatograph WATERS 610. A solution of the polymer in chloroform at a concentration of 1mg/mL was prepared. 100 pl of this solution is injected, through a filter having pores of 0.2 pm in diameter, in the column of the chromatograph at °C. The molecular weight is given on the basis of the retention time in the column. One sample is carried out as the nce using standard polystyrene s and a universal calibration curve. 3. Determination of the shrinkage/warpage of the moulded object The measurement of the rotomoulded article compared to the mould itself is done by three-dimensional analysis according to the method described in ational patent application published .

The average withdrawal measured on the moulded object is expressed in % compared to the internal volume of the mould. 4. Determination of the aspect of the walls of the moulded object The aspects of the interior and exterior walls, uniformity, presence of bubbles, ripples etc were visually evaluated.

. Determination of the regularity thickness of the walls of the moulded object The regularity ess of the walls is determined by tomography, technique well-known by the man of art.

Example 1 Resins used in the examples The resins identified ter were used: As the polyolefin, the following polyethylenes were used.

Resin 1: M4041UV® from Total Petrochemicals The white polyethylene powders were obtained after grinding the polyethylene s.

The polyethylene having a density of 0.940 g/cm3 (ISO 1183) and melt index Ml2 of 4 g/10 min (ISO 1133 condition D under a load of 2.16 kg at 190°C). The average particle size of the powder after grinding is of 300 pm. The polyethylene was prepared with ethylene bis(tetrahydroindenyl) zirconium dichloride catalyst. The tensile modulus is around 800 MPa measured according to ISO527.

Resin 2: M3581 UV® from Total Petrochemicals The white polyethylene powders were obtained after grinding the polyethylene pellets.

The polyethylene having a density of 0.935 g/cm3 (ISO 1183) and melt index MI2 of 6 g/10 min (ISO 1133 condition D under a load of 2.16 kg at 190°C). The average particle size of the powder after grinding is of 300 pm. The polyethylene was prepared with ethylene bis(tetrahydroindenyl) ium dichloride catalyst. The tensile modulus is around 800 MPa measured ing to ISO527.

Resin 3: M3671® from Total Petrochemicals The white polyethylene powders were obtained after ng the polyethylene s.

The hylene having a y of 0.941 g/cm3 (ISO 1183) and melt index MI2 of 3.5 g/10 min (ISO 1133 condition D under a load of 2.16 kg at 190°C). The average particle size of the powder after grinding is of 300 pm. The polyethylene was prepared with ethylene bis(tetrahydroindenyl) ium dichloride catalyst. The tensile s is around 800 MPa measured according to ISO527.

Polyester Resin 4: As the polyester a PLA was used, namely a poly-L-Iactide (PLA HIGH PURITY from Futerro®) in the form of powder obtained after grinding pellets of PLLA having an optical purity of at least 99% w/w, a water content of maximum 250 ppm, free Iactide content of maximum 0.1 % w/w and a number average lar weight Mn of approximately 100,000 (using a polystyrene reference). The average particle size of the particles of the powder after grinding is of 300 um.

Physical Properties of the PLA: 0 ic Gravity at 25°C of 1.24 measured according to ISO 1183. 0 Melt density at 230°C of 1.08-1.12. 0 Melt index measured at 190°C under a load of 2.16 kg of 10-30 g/10min measured according to ISO 1133. 0 Melt index measured at 210°C under a load of 2.16 kg of 30-60 g/10min measured according to ISO 1133.

WO 34702 0 Haze at 2mm thickness of less than 5%, measured according to ISO 14782. 0 Transmittance at 2mm thickness of greater than 90%, measured ing to ISO 14782/ 0 Glass transition temperature of 52-60°C ed according to ISO 11357. o Crystalline melt temperature of 145-175°C also measured according to ISO 11357. 0 The tensile modulus is around 4000 MPa measured according to ISO527.

Copo/ymer Resin 5: Lotader 8840®(sold by Arkema®) was used as the copolymer compatibilising agent. LOTADER® AX8840 is a random copolymer of ethylene and glycidyl methacrylate, polymerized under high-pressure in an autoclave s.

Physical properties of Lotader® as sold: 0 Melt index measured at 190°C under a load of 2.16 kg of 5 g/10min measured according to ISO 1133 0 Glycidyl methacrylate content of 8 wt% as measured by FTIR o Ethylene monomer of 92 wt% as measured by FTIR 0 Density (at 23°C) of 0.94 g/cm3 measured ing to ISO 1183 o Melting point at 106 °C ed according to ISO 11357-3 The following are given as physical ties measured on compression moulded o Vicat softening point (at 10N) of 87 °C measured according to ISO 306 0 e modulus of 104 MPa measured according to ISO 527-2 0 Flexural modulus of 85 MPa measured according to ISO 178 0 Elongation at break of 400 % measured according to ISO 527-2 0 Tensile strength at break of 8 MPa measured according to ISO 527-2 0 Hardness Shore D (at 1s) of 50 measured according to ISO 868 Compositions for Layer A The following compositions for layer A according to the invention were prepared. 0 Composition 1 = Compounded and formed to micropellets 300 pm average particle size — Resin 2 = 88 wt% — Resin 4 PLA High Purity Futerro® = 10 wt% — Green Master batch color (pigment Gymap® GM11725) = 2 wt% 0 Composition 2 = Compounded and formed to micropellets 300 pm in average le size — Resin 2 = 86 wt% — PLA high Purity Futerro® = 10 wt% — Green Master batch color (pigment Gymap® GM11725) = 2 wt% — Lotader 8840® (Arkema®) = 2 wt% 0 Composition 3 = Compounded and formed to micropellets 300 pm in average particle size — Resin 2 = 81 wt% — PLA high Purity Futerro® = 15 wt% — Green Master batch color (pigment Gymap® 5) = 2 wt% — Lotader 8840® (Arkema®) = 2 wt% Composition 4 and 5 are ous to compositions 1 and 2, however using Resin 1 instead of Resin 2. These were tested for impact strength. 0 Composition 4 = Compounded and formed to micropellets 300 pm in average particle size — Resin 1 = 88 wt% — PLA high Purity o® = 10 wt% — Green Master batch color (pigment Gymap® 5) = 2 wt% 0 Composition 5 = Compounded and formed to micropellets 300 pm in average particle size — Resin 1 = 86 wt% — PLA high Purity Futerro® = 10 wt% — Green Master batch color (pigment Gymap® GM11725) = 2 wt% — Lotader 8840® (Arkema®) = 2 wt% Compositions 1 to 5 have a tensile modulus measured according to ISO527 of around 1100 MPa.

Machine and Mould Configuration A carousel oven machine was used, wherein the process with following conditions were present: 0 Oven set temp for all trials 270°C 0 Aluminium moulds 0 al air cooling only. Air was used at room temperature (between 20 to 25°C) 0 A dropbox used for all additional layers to form the ayered articles Manufacture of single layered bottles by rotational moulding These were carried out on a “FERRY Rotospeed RS2 — 160 Independent Arm” rotomoulding e having a swing diameter of 1.6m.

Bottles were rotomoulded having the shape and dimensions as indicated in FIGURE 1.

The temperature cycle is shown in FIGURE 2. The ters are the following: - Heating of the oven to a temperature of 300°C - PIAT (peak internal air temperature): 230°C - onal ratio: 4/1 - Cooling of the mould from the outside from 230°C at a rate of 3°C / minute using air at room temperature to 50°C - e from the mould at 50°C Various bottles from the powders as mentioned above are used separately to form bottles by rotomoulding, namely using o BOTTLE 1: Only Resin 2 alone to form a rotomoulded bottle according to the prior 0 BOTTLE 2: Composition 2 to form a rotomoulded bottle according to the invention 0 BOTTLE 3: Composition 3 to form a rotomoulded bottle ing to the invention The internal and external surface s of the walls were examined. The surface of the bottles according to the invention were shinier and smoother than the bottle of the prior art.

The shrinkage and warpage of the es with respect to the mould were analyzed (see ). The rotomoulded article and the mould have been scanned: 0 Approximately 540000 points of comparison were carried out on both the article and the mould 0 The nce mould/part” comparison was analyzed using Statistica®8.0 software. 0 The Mean distance between the article and the mould was accordingly determined 0 Box & whisker plots were carried out. o The dispersion index was calculated (inter quartile split) (Reference: « La boite a Moustache de Tukey » a Statistics tool by Monique Le Geun (available on the Internet)) The results are presented in table 1.

TABLE 1 Biggest Dispersion Mean distance (mm) between index (mm) mould/bottle (mm) BOTTLE 1 news (invention) ——-n.2 It can be seen that s 2 and 3 ing to the invention have a smaller mean ce from the mould, meaning that both bottles 2 and 3 shrunk and warped less than the bottle 1 according to the prior art.

Thus, the ce of the PLA improves the shrinkage and warpage of the rotomoulded article.

The presence of copolymer (Lotader 8840®) also improves impact strength, as can be seen in Table 2 below. The Charpy impact th was tested on injection moulded samples according to ISO 179/1eU and 1eA at 23°C. The presence of only 2wt% of copolymer according to the invention greatly improves the impact strength of the composition.

WO 34702 TABLE 2 Composition Charpy Impact Strength Charpy Impact Strength None notched sample d sample according to ISO 179/1 eU according to at 23°C ISO 179l1eA at 23°C (in lem2) (in lem2) Composition 1 absence of Lotader 8840® ition 2 (2wt% of Lotader 8840®) ntion 4 absence of Lotader 8840® Composition 5 (2wt% of Lotader 8840®) Manufacture of 3-layered car parts by onal moulding These were manufactured according to TP-SEAL® technology.

The three layers consist of an outer “skin” layer, an intermediate foamed layer and an inner “skin” layer.

A car part (part of a car body) was manufactured by rotational moulding, as shown in FIGURE 3 and 4a and 4b.

The temperature cycle is shown in FIGURE 5. The parameters are the following: - Heating of the oven to a temperature of 270°C - PIAT 1(peak internal air temperature): 140°C -P|AT 2: 140°C -P|AT 3: 170°C - rotational ratio: 4/1 - Cooling of the mould from the outside from 180°C at a rate of 3°C / minute using air at room temperature to 100°C - Release from the mould at 100°C.

Car parts of different compositions were rotomoulded, namely: CAR 1: according to the prior art -> no polyester 0 Outer Layer: 15 kg of Resin 1 dry blended with 15 kg of Resin 3 (introduced while starting the cycle) 0 Intermediate Foamed layer: 15 kg of Resin 3 dry blended with 2wt% of Genitron OB® chemical blowing agent (dropped into mould during cycle) 0 Inner layer: 10 kg of Resin 2 (dropped into mould during cycle) CAR 2: according to the ion -> PLA and mer Lotader 8840® present in layer 0 Outer Layer A: 30 kg of Composition 2 (introduced while starting the cycle) 0 Intermediate Foamed layer B: 15 kg of Resin 3 dry blended with 2wt% of Genitron OB® al blowing agent ed into mould during cycle) 0 Inner layer C: 10 kg of Resin 2 (dropped into mould during cycle) CAR 3: according to the invention -> PLA and copolymer Lotader 8840® present in layer 0 Outer Layer A: 15 kg of Composition 1 dry blended with 15 kg of Composition 2 (introduced while starting the cycle) 0 Intermediate Foamed layer B: 15 kg of Resin 3 dry blended with 2wt% of Genitron OB® chemical blowing agent (dropped into mould during cycle) 0 Inner layer C: 10 kg of Resin 2 (dropped into mould during cycle) The internal and external surface aspects of the walls were examined. The surface of the bottles according to the invention were shinier and smoother than the bottle of the prior art.

The shrinkage and warpage of the articles with respect to the mould were analyzed (see ). The rotomoulded car part and the mould have been scanned: 0 imately 1,600,000 points of comparison were d out on both the e and the mould 0 The “distance mould/car part” comparison was analyzed using Statistica®8.0 software. 0 The Mean distance between the article and the mould was accordingly determined 0 Box & whisker plots were carried out. o The dispersion index was ated (inter quartile split) (Reference: « La boite a Moustache de Tukey » a Statistics tool by Monique Le Geun (available on the Internet)) The results are presented in Table 3.

TABLE 3 Dispersion index (mm) It can be seen that Car parts 2 and 3 according to the invention have a smaller mean distance from the mould, meaning that both Car parts 2 and 3 shrunk and warped less than the Car part 1 according to the prior art.

Thus, the ce of the PLA improves the shrinkage and warpage of the rotomoulded article.

Example 2 The resins identified hereafter were used: Po/yolefln Resin 1: M4041UV® from Total Petrochemicals The white polyethylene s were ed after grinding the polyethylene pellets.

The polyethylene having a density of 0.940 g/cm3 (ISO 1183) and melt index MI2 of 4 g/10 min (ISO 1133 condition D under a load of 2.16 kg at 190°C). The average particle size of the powder after grinding is of 300 pm. The polyethylene was prepared with ethylene bis(tetrahydroindenyl) zirconium dichloride catalyst. The tensile modulus is around 800 MPa measured according to .

Resin 2: M3581 UV® from Total hemicals The white polyethylene powders were obtained after grinding the polyethylene s.

The polyethylene having a density of 0.935 g/cm3 (ISO 1183) and melt index MI2 of 6 g/10 min (ISO 1133 condition D under a load of 2.16 kg at 190°C). The average particle size of the powder after grinding is of 300 pm. The hylene was prepared with ethylene bis(tetrahydroindenyl) zirconium dichloride catalyst. The tensile modulus is around 800 MPa measured according to ISO527.

Polyester Resin 6: NatureWorks® PLA polymer 6201 D 2012/067529 As the polyester a PLA was used, namely a poly-L-lactide (NatureWorks® PLA polymer 6201 D) in the form of powder obtained after grinding pellets of PLLA.

Physical Properties of the PLA: 0 Specific y at 25°C of 1.24 measured according to D792. 0 Melt density at 230°C of 1.08. 0 Melt index measured at 210°C under a load of 2.16 kg of 15-30 g/10min measured according to D1238. 0 Glass transition temperature of C measured according to D3417. 0 Crystalline melt temperature of 160-170°C also measured according to D3418.

Copo/ymer Resin 5: Lotader 8840®(sold by ®) was used as the copolymer compatibilising agent. LOTADER® AX8840 is a random copolymer of ethylene and glycidyl methacrylate, rized under high-pressure in an autoclave process. Physical properties of Lotader® as described in example 1.

Compositions for Layer A The following compositions for layer A according to the invention were prepared. ition 7 = nded and formed to micropellets 300 um average particle size 0 Resin 2 = 88 wt% 0 Resin 6 = 10 wt% 0 Green Master batch color (pigment Gymap® GM11725) = 2 wt% Composition 8 = Compounded and formed to micropellets 300 pm in average particle size 0 Resin 2 = 86 wt% 0 Resin 6 = 10 wt% 0 Green Master batch color (pigment Gymap® GM11725) = 2 wt% 0 Resin 5: Lotader 8840® (Arkema®) = 2 wt% Composition 9 = Compounded and formed to micropellets 300 pm in average particle size 0 Resin 2 = 81 wt% 0 Resin 6 =15wt% 2012/067529 0 Green Master batch color (pigment Gymap® 5) = 2 wt% Resin 5: Lotader 8840® (Arkema®) = 2 wt% 0 Composition 13 = Compounded and formed to micropellets 300 pm in average particle size 0 Resin 1 = 88 wt% 0 Resin 6 = 10 wt% 0 Green Master batch color (pigment Gymap® GM11725) = 2 wt% Composition 14 = Compounded and formed to micropellets 300 pm in average particle size 0 Resin 1 = 86 wt% 0 Resin 6 = 10 wt% 0 Green Master batch color (pigment Gymap® GM11725) = 2 wt% 0 Resin 5: Lotader 8840® (Arkema®) = 2 wt% Composition 14 had a density of about 0.950 or superior to 0.950 g/cm3 as ed according to ISO 1183, a Melt index as ed at 190°C under a load of 2.16 kg of 4 g/10min (measured according to ISO ). The Flexural modulus is around 900 MPa measured according to ISO 178. The tensile strength at yield is around 18 MPa measured according to ISO 527-2. The tensile strength at break is around 16 MPa measured ing to ISO 527-2. The elongation strength at yield is around 10 % measured according to ISO 527-2. The elongation strength at break is around 500 % measured according to ISO 527-2.

Composition 15 = Compounded and formed to micropellets 300 pm in average particle size 0 Resin 1 = 76 wt% 0 Resin 6 = 10 wt% 0 Green Master batch color (pigment Gymap® GM11725) = 2 wt% 0 Resin 5: Lotader 8840® (Arkema®) = 2 wt% 0 demoulding agent: CaC03 or talc 10 wt% The compositions were compounded on a co-rotative twin screw extruder 60 mm diameter, L/D = 40.

All the compositions were ground into powder at room temperature to produce a powder with following teristics: Bulk density: 0.30 to 0.40 g./cm3 Dry flow: 20 to 30 seconds Grinding of the composition was performed at room temperature and with the same throughput as the resin 1 (mPEM4041 UV) (market reference for grinding capability).

The compositions were also produced in e||et form with ing characteristics: Bulk density: > 0.45 g./cm3 Dry flow : < 20 seconds.

Tensile analysis of composition 14 compared to resin 1 showed that the PLA used in the composition was at least partly crystalline. This can be observed in FIGURE 6 where the tensile modulus for resin 1 and ition 14 is plotted as a function of temperature.

This figure shows that PLA used in the resin composition 14 is at least partly crystalline, since if the PLA was not in crystalline form the modulus would drop close to zero after 60°C (above PLA Tg) as shown in Table 4. Tensile analysis was performed by measuring the non-linear viscoelastic properties. The ements were carried out with the raction® system developed by Company APOLLOR. The VideoTraction® system tracks in real-time the barycentres of markers deposited on the sample surface and pilots the testing e according to the material's behavior. The system uses movie camera, image analysis and data acquisition, the whole joined together in a PC. Tensile tests were carried out at constant local strain rate at 23°C, 40°C and 80°C. Longitudinal and transversal deformations were measured. The true stress was calculated according to the hypothesis of transverse isotropy.

TABLE 4 pure PLA modulus as a function of Temperature and microstructure: 39'0“” s (MPa) 4366 3916 397.8 3602 3532 _T9/ ”0 measure. < 10 Mpa Manufacture of sin le la ered bottles b rotational n Rotomoulded bottles were produced with all the compositions with a wall ess 4.5 mm and Peak internal air temperature (PIAT ) = about 210°C.

The bottles were produced using two release agents in the mould: -non permanent release agent: using Frekote® from Henkel -permanent release agent: Teflon.

The easiness of release of the es with respect to the mould were ed. __The results are shown in Table 5.

TABLE 5: demoulding easiness "easine55” to d Al uminium mouldj’ Freeimte release agent Aluminium mum ld fTeflon coated niooowii coinnooinon i Conn-onion ,3 coin nooiiion o Conwnosiiion 13 mono-onion in c-omoooiiion in 3D age The 3D shrinkage was evaluated as described in example 1, following the method described in . 3D shrinkage was assessed using a mould of 8.615 liters in volume. This mould was used on a Ferry Carousel machines (Standard oven type). A 3D optical scanning was made of the inner surface of the mould. A 3D optical scan was made of the rotomoulded article and a best fit calculation was done to compare the mould and the e.

The rotomoulded article and the mould have been scanned: imately 330000 points of comparison were carried out on both the article and the mould. A design of experiment (DOE) was performed to obtain the correlation between material, processing conditions and 3D volume ties of rotomoulded articles. This DOE was used to calculate 3D “shrinkage”. The average 3D deviation was used calculate the 3D shrinkage with the on: y(% shrinkage) = -1.2298103 + -2.9087107 x (Avg 3D deviation) The results are presented in FIGURE 7. The results confirms that compositions according to the ion present much less shrinkage compared to the polyethylene resins. g behavior: The sagging behaviors of compositions 8 and 9 were analyzed and compared to the behavior of resin 1 following the method described herein: 2012/067529 The analysis of g behavior in rotational moulding machines were made on a cube mould having the ing dimension 330x300x300 mm.

An article with “exaggerated” sagging was first produced, by stopping the mould in vertical position at the end of the heating cycle with Peak internal air temperature at 230°C (sagging part). In parallel to this moulding, an article was produced in standard condition with an internal air temperature of ~ 210°C (reference article). 3D scanning of both articles were then produced (with about 150000 to 400000 points of thickness measurement) and the results are compared to give a ng percentage”. resin 1 is a reference resin in the tank market in terms of processability and low sagging behavior. The results are shown in FIGURE 8 which shows the g or expressed in % for resins 1 and 2 and compositions 8 and 9.

Comparatively, a two-layers comparative article was made with an outer layer made of resin 2, and a foamed inner layer. The comparative article presented sagging as shown in FIGURE 9. This figure shows that resin 2 is sensitive to sagging, this generates deformation inside and e the article.

Stress cracking Stress cracking of compositions 13, 14 were compared to resin 1 following the procedure described in standard ASTM D1693, conditions B , lgepal CO630/ 10% in water. The results are shown in FIGURE 10. The figure shows a remarkable improvement in ESCR for ition according to the ion.

Article filling with polyurethane foam In this experiment, a single-layered car part, comprising composition 14, was produced by rotational moulding with a PIAT at 190°C. A carrousel machine (Model Carrousel RC 4000 from Roto Plastic International srl) was used, with aluminium moulds.

The car part did not stick to the mould walls, such that demoulding of the part was straightforward. Moreover, the surface finish was excellent.

The car part was then filled with a PU foam such as Soudafoam FR from Soudal. One hour after filling the part with the composition, the part was cut and pictures were taken as shown in FIGURE 11. It was found that the part was tely filled with the PU foam. It was surprising that the bond in between the composition 14 and the PU foam was very good.

A comparison with a similar single-layer car part produced with resin 2 was made. The results are shown in FIGURE 12, where it can be seen that in contrast with the car part according to the ion, there was no adhesion of the PU foam to the car part made with resin 2.

Claims (15)

1. A rotomoulded article comprising one or more layers wherein a layer A comprises:  from 50 to 99.4 wt% of a polyolefin;  from 0.5 to 49.9 wt% of a polyester, wherein said polyester is an aliphatic polyester selected from polyhydroxyalkanoate, poly(lactic acid), polycaprolactone, esters and polyesteramides;  from 0.1 to 20 wt% of a co- or ter-polymer comprising a) 50 to 99.9 wt% of ethylene or styrene monomer; b) 0.1 to 50 wt% of an unsaturated anhydride-, epoxide- or carboxylic acidcontaining monomer; and c) 0 to 50 wt% of a (meth)acrylic ester monomer.

2. The article according to claim 1, wherein the ter is a poly(lactic acid).

3. The article according to any one of claims 1 or 2, n the polyolefin is a polyethylene.

4. The article according to any one of claims 1 to 3, wherein the unsaturated anhydride-, epoxide-, or carboxylic acid-containing monomer is selected from maleic anhydride, or glycidyl methacrylate.

5. The article ing to any one of claims 1 to 4, wherein the acrylic ester monomer is t from 0.1 to 50 wt% of the terpolymer and is selected from methyl, ethyl, n-butyl, iso-butyl, 2-ethylhexyl, or n-octyl (meth)acrylate.

6. The article according to any one of claims 1 to 5, wherein the e comprises a layer B1 comprising from 50 to 100 wt% of an aliphatic polyester selected from polyhydroxyalkanoate, poly(lactic acid), polycaprolactone, esters and polyesteramides.

7. The article according to claim 6 wherein layer B1 is adjacent to layer A.

8. The article according to any one of claims 6 or 7 wherein the aliphatic ter is a poly(lactic acid).

9. The article according to any one of claims 6 to 8, comprising layers A and B1, wherein:  layer A is the outer layer, 0 layer B1 is the inner layer.

10. The article according to any one of claims 1 to 9 wherein the article comprises a layer B comprising from 50 to 100 wt% of a polyolefin, ably adjacent to layer A.

11. The article according to claim 10 wherein the polyolefin of layer B is a polyethylene.

12. The article according to any one of claims 10 or 11, wherein said layer B is foamed.

13. The article according to any one of claims 10 to 12 comprising layers A, B and B1, wherein: 0 layer A is the outer layer, 0 layer B is the intermediate layer adjacent to layer A and layer B1, 10 0 layer B1 is the inner layer.

14. The article according to any one of claims 1 to 13, wherein said article ses at least one cavity provided with polyurethane.

15. The article according to any one of claims 1 to 14 wherein the e is a bottle, a can, a tank or a car part, preferably a car door or car body.