FR2956405A1 - Composition, useful in part or object, comprises polyhydroxyalkanoic acid, core-shell elastomeric compound and olefin copolymer comprising ethylene monomer having an epoxy function - Google Patents

Abstract

Composition (I) comprises: polyhydroxyalkanoic acid; a core-shell elastomeric compound; and an olefin copolymer comprising ethylene monomer having an epoxy function. Independent claims are included for: (1) preparing (I) comprising mixing or extruding the mixture of polyhydroxyalkanoic acid, a core-shell elastomeric compound, the olefin copolymer, optionally an additional olefin polymer and optionally additives such as nucleating agent; (2) part or object, such as a package comprising (I); and (3) manufacturing a part or object comprising forming (I) by injection, pressing or calendering, where the part or object optionally undergoes an annealing step.

Description

Technical Field: The present invention relates to a polyhydroxyalkanoate (PHA) composition having improved impact resistance.

STATE OF THE ART Polyhydroxyalkanoate or polyhydroxyalkanoic acid (PHA) polymers, such as poly lactic acid (PLA), are polymers which can be obtained from a monomer of plant origin. Because of their biodegradable properties, they are of major interest.

However, these are particularly fragile polymers that require impact reinforcement. In the state of the art, JP H09-316310 describes PLA compositions containing ethylene-glycidyl methacrylate copolymers grafted with polystyrene or polydimethacrylate or polyolefins grafted with maleic anhydride. More recently, WO 2005/059031 discloses a PLA composition comprising from 3 to 40% by weight of a copolymer of ethylene, a carboxylic acid ester and a glycidyl ester. In US 2008/0071008 is described a composition of polyhydroalkanoic acid comprising from 0.2 to 10% of core-shell compound having a refractive index of less than 1.5 and not comprising vinyl aromatic monomer. These compositions certainly have improved impact resistance, however, this resistance is not completely satisfactory, especially at a temperature below 20 ° C. On the other hand, some of these compositions have a fluidity significantly lower than that of PHA. This significant drop in fluidity is detrimental to the implementation, especially for fine and large injected parts.

The object of the present invention is to provide a novel PHA composition which has good impact resistance, especially at low temperature.

Summary of the Invention: The present invention relates to a polyhydroxyalkanoate (PHA) composition further comprising a core-shell elastomeric compound (A) and an olefinic copolymer (B) comprising an epoxy functional ethylenic monomer. This particular composition comprising an impact modifier combining a core-shell compound with an olefinic copolymer has exceptional shock properties and, surprisingly, much greater than those of the compositions of the prior art and in particular far superior to compositions comprising a shock modifier consisting of an olefinic copolymer comprising an epoxy functional ethylenic monomer or a core-shell compound. The composition also has the advantage of having excellent fluidity during its implementation.

The epoxy functional ethylenic monomer is preferably glycidyl (meth) acrylate.

The copolymer (B) may be a copolymer of ethylene, of glycidyl methacrylate and optionally an acrylate and / or an alkyl methacrylate whose alkyl chain comprises from 1 to 30 carbon atoms, these being grouped under the alkyl (meth) acrylate term in the present description. The amount of alkyl (meth) acrylate may be in the range of 0 (i.e., does not include) to 40% based on the total weight of said olefinic copolymer (B ), advantageously from 5% to 35%, preferably from 20% to 30%. The amount of epoxy functional ethylenic monomer in said olefinic copolymer (B) is, for example, in the range of from 0.1 to 20% relative to its total weight, preferably from 2 to 15%, and preferably from 5 to 10% by weight. at 10%.

The composition may also further comprise an additional olefinic polymer (C) other than olefinic copolymers comprising an epoxy functional ethylenic monomer. Preferably, this additional olefinic polymer (C) is a copolymer of ethylene and an alkyl (meth) acrylate, a copolymer of ethylene and a vinyl ester of carboxylic acid, a copolymer of ethylene and of a (meth) acrylic acid or an ionomer, most preferably a copolymer of ethylene and an alkyl acrylate having an alkyl chain ranging from 1 to 20 such as for example methyl acrylate, acrylate and the like. ethylene or n-butyl acrylate. In this case, the composition advantageously has a mass ratio (B) / (C) in the range of 90/10 to 10/90, preferably 75/25 to 40/60.

Advantageously, the weight ratio (A) / ((B) + (C), if any) is in the range from 90/10 to 10/90, for example 85/15 to 40/60, more preferably 80/60. 20 to 50/50 and preferably 75/25 to 60/40.

The amount of modifier ((A) + (B) + (C), if any) may be in the range from 1 to 30% by weight of the total composition, advantageously from 2 to 15%, preferably from 3 to 9%. . The amount, in polymerized form, of ethylenic monomer comprising an epoxy functional group may be in the range from 0.01% to 2%, advantageously from 0.02 to 1%, preferably from 0.03 to 0.7%, relative to to the mass of the total composition. With regard to the elastomeric core-shell compound (A), the glass transition temperature of the core polymer is preferably less than 20 ° C, for example between -140 ° C and 0 ° C. Preferably, the glass transition temperature of the core polymer 30 is greater than 20 ° C, for example between 30 ° C and 250 ° C. With regard to the elastomeric core-shell compound (A), its shell portion preferably comprises in polymerized form: an alkyl methacrylate whose alkyl chain comprises from 1 to 12 carbon atoms, preferably from 1 to 4; and / or a vinyl aromatic organic compound comprising from 6 to 12 carbon atoms such as styrene; and / or acrylonitrile; this bark portion being or not crosslinked.

The core portion of the core-shell compound (A) advantageously comprises in polymerized form: a conjugated diene comprising from 4 to 12 carbon atoms, preferably from 4 to 8; or an alkyl acrylate whose alkyl chain comprises from 1 to 12 carbon atoms, preferably from 1 to 8.

The core-shell compound (A) may be chosen from: a compound having a core comprising butadiene and a bark comprising methyl methacrylate, ethyl acrylate, butyl acrylate and methacrylic acid and / or styrene; a compound having a core comprising butyl acrylate, n-octyl acrylate and / or 2-ethylhexyl acrylate and a bark comprising methyl methacrylate; a compound having a core comprising butadiene and a bark comprising a mixture of acrylonitrile and styrene.

As regards the core-shell compound, the amount of core mass is advantageously in the range of 10 to 99% of the total mass of the core-shell compound, for example 60 to 95%. The size of the core-shell compounds is advantageously between 50 and 600 nm.

Preferentially, the PHA is chosen from lactic acid polyacid (PLA) and glycolic polyacid (PGA).

The subject of the invention is also a process for preparing the modified PHA composition in which the mixture of PHA, (A), (B) and (C), optionally with one or more additives, is extruded by extrusion. a nucleating agent.

According to a preferred process of the invention, a mixture of (A), (B) and (C), if any, is produced to form an impact modifier in a first step and then, in a second step, the mixture of the impact modifier resulting from the first step with the PHA.

An object of the invention is a part or object, such as a package comprising the modified PHA composition.

The invention also relates to a method of manufacturing the part or object comprising a step of shaping said composition, for example by injection, pressing or calendering, said part or said object possibly undergoing an annealing step.

Detailed description of the invention

The present invention relates to a polyhydroxyalkanoate (PHA) composition further comprising a core-shell (A) compound and a polymer comprising an epoxy functional ethylenic monomer (B).

According to the invention, when one of the polymers of the composition or a composition "comprises a monomer", it means that it is present in polymerized form in said polymer or a polymer (or polymers) of said composition.

PHA type polymers are biodegradable polymers.

Some of them are also biorenewable, the monomers being produced by fermentation processes by bacteria or plant extracts. The term "biodegradable" applies to a material if it can be degraded by microorganisms. The result of this degradation is the formation of water, CO2 and / or CH4 and, possibly, by-products (residues, new biomass) that are not toxic to the environment. For example, EN13432 can be used to determine if the material is biodegradable. To determine whether a polymer is "biorenewable", ASTM D 6866 can be used. Biorenewable polymers are characterized by having carbon of renewable origin, i.e., 14C. Indeed, all the carbon samples taken from living organisms and in particular from the plant material used to form the biorenewable polymers, are a mixture of three isotopes: 12C, 13C and 14C in a ratio 14C / 12C kept constant by continuous exchange of carbon with the environment which is equal to 1.2 x 10-12. Although 14C is radioactive and its concentration decreases over time, its half-life is 5730 years, so it is estimated that the 14C content is constant from the extraction of plant material to the manufacture of biorenewable polymers and even until the end of their use. For example, it can be considered that the polymer is biorenewable when the ratio 14C / 12C is greater than or equal to 1 x 10-12. The 14C content of the biorenewable polymers can be measured, for example, according to the following techniques of liquid scintillation spectrometry or mass spectrometry. These methods of measuring the 14C content of the materials are precisely described in ASTM D 6866 (including D6866-06) and ASTMD 7026 (including 7026-04) standards. These methods measure the 14C / 12C ratio of a sample and compare it with the 14C / 12C ratio of a 100% renewable source reference sample to give a relative percentage of renewable carbon in the sample. The measurement method preferably used in the case of biorenewable polymers is the mass spectrometry described in the ASTM D6866-06 standard ("accelerator mass spectroscopy"). PHAs are polymers comprising hydroxyalkanoic acid units, for example having 2 to 10 carbon atoms. Examples include the polymer comprising 6-hydroxyhexanoic acid known as polycaprolactone (PCL), the polymers comprising 3-hydroxyhexanoic acid, 4-hydroxyhexanoic acid or 3-hydroxyheptanoic acid. Particularly noteworthy are polymers having 5 or less carbon atoms, for example polymers comprising glycolic acid (PGA), lactic acid (PLA), 3-hydroxypropionate, 2-hydroxybutyrate, 3-hydroxybutyrate ( PHB), 4-hydroxybutyrate, 3-hydroxyvalerate, 4-hydroxyvalerate and 5-hydroxyvalerate. Preferred polymers are PGA, PCL, PLA and PHB. PHAs can be aliphatic. The PHAs may also be copolymers, that is to say comprise a first hydroxyalkanoic acid and another unit which may be either a second hydroxyalkanoic acid other than the first, or another monomer such as diols such as ethylene glycol, 1,3-propanediol and 1,4-butanediol or diacids such as succinic acid, adipic acid and terephthalic acid.

The compositions of the invention may also comprise mixtures of these polymers. PHAs are often polymerized in bulk. A PHA can be synthesized by dehydration and condensation of hydroalkanoic acid. It can also be synthesized by dealcoholization and condensation of an alkyl ester of a hydroalkanoic acid or by ring-opening polymerization of a cyclic derivative of the corresponding lactone or of the dimer of the cyclic ester. Bulk polymerization is generally carried out by a batch or continuous process. Examples of continuous PHA manufacturing processes include the processes of JP-A-03502115, JP-A 07-26001, JP-A 07-53684. US Pat. Nos. 2,668,162 and 3,297,033 describe batch processes.

As regards the core-shell copolymer (A), it is in the form of fine particles having a soft polymer core and at least one hard polymer shell, the size of the particles is generally less than the pm and advantageously between 50 and 600 nm.

Preferably, the core polymer has a glass transition temperature below 20 ° C, for example between -140 ° C and 0 ° C, preferably between -120 and -30 ° C. Preferably, the polymer of the bark has a glass transition temperature greater than 20 ° C, for example between 30 ° C and 250 ° C.

The glass transition temperatures of the polymers of the composition can be measured according to ISO 11357-2: 1999. By way of example of a core polymer, homopolymers of isoprene or butadiene, isoprene-butadiene copolymers, copolymers of isoprene with at most 98% by weight of a vinyl monomer and copolymers of butadiene with at most 98% by weight of a vinyl monomer. The vinyl monomer may be styrene, alkylstyrene, acrylonitrile, alkyl (meth) acrylate, butadiene or isoprene. The core polymer may also comprise siloxane, optionally copolymerized with an alkyl acrylate. The core of the core shell copolymer may be crosslinked in whole or in part. It suffices for this to add at least difunctional monomers during the preparation of the core, these monomers can be chosen from poly (meth) acrylic esters of polyols such as butylene di (meth) acrylate and trimethylolpropane trimethacrylate . Other multifunctional monomers are, for example, divinylbenzene, trivinylbenzene, vinyl acrylate and vinyl methacrylate, triallyl cyanurate. The core can also be crosslinked by introducing, by grafting or as comonomer during the polymerization, unsaturated functional monomers such as anhydrides of unsaturated carboxylic acids, unsaturated carboxylic acids and unsaturated epoxides. Mention may be made, for example, of maleic anhydride, (meth) acrylic acid and glycidyl methacrylate. It is also possible to crosslink using the intrinsic reactivity of the monomers, for example the dienic compounds. The bark or barks are homopolymers of styrene, an alkylstyrene or methyl methacrylate or copolymers comprising at least 70% by weight of one of these monomers and at least one comonomer chosen from the other monomers above another alkyl (meth) acrylate, vinyl acetate and acrylonitrile. The bark may be functionalized by introducing, by grafting or as comonomer during the polymerization, unsaturated functional monomers such as unsaturated carboxylic acid anhydrides, unsaturated carboxylic acids and unsaturated epoxides. Mention may be made, for example, of maleic anhydride, (meth) acrylic acid, glycidyl methacrylate, hydroxyethyl methacrylate and alkyl (meth) acrylamides. By way of example, mention may be made of core-bark copolymers having a polystyrene bark and core-bark copolymers having a PMMA bark. The bark may also contain imide functions, either by copolymerization with a maleimide or by chemical modification of PMMA with a primary amine. Advantageously, the mol% of imide functions is 30 to 60% (relative to the whole of the bark). There are also core-bark copolymers having two barks, one made of polystyrene and the other outside made of PMMA. Examples of copolymers and their process of preparation are described in the following patents: US 4,180,494, US 3,808,180, US 4,096,202, US 4,260,693, US 3,287,443, US 3,657,391, US 4,299,928. , US 3,985,704, US5773520. The core is, for example, in this invention, by weight, 5 to 95% of the core bark compound and the 5% bark 95.

By way of example of copolymer, mention may be made of (i) from 50 to 95 parts of a core comprising in moles at least 93% of butadiene, 5% of styrene and 0.5 to 1% of divinylbenzene and (ii) ) from 5 to 50 parts of two barks of essentially the same weight, one in polystyrene and the other in PMMA. Preferably, it is possible to use the core-shell compounds having a copolymer core of butyl acrylate and a PMMA bark.

These compounds have the advantage of being particularly transparent. All these core-bark compounds are sometimes called soft / hard because of the elastomeric core. It would not be departing from the scope of the invention by using core-shell copolymers such as hard / soft / hard, ie copolymers which have in this order a hard core, a soft bark and a hard bark. The hard parts may consist of the above soft / hard bark polymers and the soft part may consist of the above soft / hard core polymers. Mention may be made, for example, of those described in EP 270865, and those constituted in this order: of a copolymer core of methyl methacrylate and ethyl acrylate, of a bark made of butyl acrylate copolymer and styrene, a bark copolymer of methyl methacrylate and ethyl acrylate.

There are still other types of core bark copolymers such as hard (heart) / soft / medium hard. Compared to the previous ones, the difference comes from the outer bark "mi dur" which consists of two barks: one intermediate and one outer. The intermediate bark is a copolymer of methyl methacrylate, styrene and at least one monomer selected from alkyl acrylates, butadiene and isoprene. The outer bark is a PMMA homopolymer or copolymer. Mention may be made, for example, of those consisting of: a copolymer core of methyl methacrylate and of ethyl acrylate, of a bark made of butyl acrylate and styrene copolymer, of a bark copolymer of methyl methacrylate, butyl acrylate and styrene, a bark copolymer of methyl methacrylate and ethyl acrylate. Compounds (A) are marketed by the applicant under the Biostrength®, Durastrength® and Clearstrength® brands.

The polymer (B) comprises an ethylenic monomer carrying an epoxy function. Preferably, it is a statistical copolymer. The epoxy functional ethylenic monomer is an unsaturated epoxide such as: aliphatic glycidyl esters and ethers such as allyl glycidyl ether, glycidyl ether vinyl, glycidyl maleate and itaconate, glycidyl (meth) acrylate, and alicyclic glycidyl esters and ethers such as 2-cyclohexene-1-glycidyl ether, cyclohexene-4,5-diglycidyl carboxylate, cyclohexene-4-glycidyl carboxylate, 5-norbornene-2-methyl-2-glycidyl carboxylate and endo cisbicyclo (2,2,1) -5-heptene-2,3-diglycidyl dicarboxylate. Glycidyl methacrylate is preferred as the epoxy functional ethylenic monomer. Preferably, the polymer (B) is an olefinic copolymer comprising an epoxy functional ethylenic monomer, ie it is a copolymer of the abovementioned ethylenic monomer and at least one alpha-olefin, which may comprise from 2 to 20 carbon atoms, such as ethylene or propylene, preferably ethylene. The olefinic copolymer may further comprise at least one monomer different from the aforementioned alpha-olefins and the epoxy functional ethylenic monomer. Nonlimiting examples include: a conjugated diene, such as, for example, 1,4-hexadiene; - carbon monoxide; An unsaturated carboxylic acid ester such as, for example, alkyl (meth) acrylates; A saturated carboxylic acid vinyl ester such as, for example, vinyl acetate or vinyl propionate. According to an advantageous embodiment, the olefinic copolymer comprises an alkyl (meth) acrylate. The alkyl chain can have up to 24 carbons. Preferred are those whose alkyl chain comprises from 1 to 12 carbon atoms, advantageously from 1 to 6, or even from 1 to 4. Advantageously, the (meth) acrylates of alkyl are n-butyl acrylate, acrylate isobutyl acrylate, 2-ethylhexyl acrylate, ethyl acrylate and methyl acrylate. Preferably, the alkyl (meth) acrylates are n-butyl acrylate, ethyl acrylate and methyl acrylate. Most preferably, it is methyl acrylate. The most preferred polymers are ethylene-alkyl acrylate-glycidyl methacrylate copolymers and ethylene-glycidyl methacrylate copolymers.

The amount of monomer other than the epoxy functional ethylenic monomer and alpha-olefins, such as the alkyl (meth) acrylate, can be in the range of 0 (i.e. does not comprise) at 40% relative to the total mass of said olefinic copolymer (B), advantageously from 5% to 35%, preferably from 20 to 30%.

The amount of epoxy functional ethylenic monomer in said olefinic copolymer (B) is, for example, in the range of from 0.1 to 20% relative to its total weight, preferably from 2 to 15%, and preferably from 5 to 10% by weight. at 10%. Copolymers (B) are marketed by the applicant under the trademark Lotader®. The composition of the invention may also comprise an additional olefinic polymer (C) such as, for example, copolymers of ethylene different from (B), that is to say not comprising monomer bearing an epoxy function. These can be chosen from copolymers comprising ethylene and a vinyl ester or copolymers comprising ethylene and an alkyl (meth) acrylate, such as copolymers consisting of ethylene and a (meth) ) alkyl acrylate. The alkyl chain of the (meth) acrylate can have up to 20 carbons. Preferred are those whose alkyl chain comprises from 1 to 12 carbon atoms, advantageously from 1 to 6, or even from 1 to 4. Advantageously, the (meth) acrylates of alkyl are n-butyl acrylate, acrylate isobutyl acrylate, 2-ethylhexyl acrylate, ethyl acrylate and methyl acrylate. Preferably, the alkyl (meth) acrylates are n-butyl acrylate, ethyl acrylate and methyl acrylate. Preferably, the amount of alkyl (meth) acrylate ranges from 1 to 40% relative to the total weight of said olefinic copolymer (C), advantageously from 5% to 35%, preferably from 20 to 30%.

Copolymers (C) are marketed by the applicant under the trademark Lotryl®. The amounts of the various monomers present in the various polymers of the invention can be measured by infrared spectroscopy, for example using the method described in the ISO8985 standard.

The processes for producing copolymers (B) and (C) are known. They can be produced by radical polymerization at high pressure, for example in a tubular reactor or autoclave.

In a most preferred embodiment of the invention, the hydroxyalkanoic acid polyacid (PHA) composition further comprises: (A) an elastomeric core-shell compound; (B) a copolymer selected from copolymers of ethylene and glycidyl methacrylate; and (C) a copolymer of ethylene and an alkyl (meth) acrylate of which the alkyl chain comprises from 1 to 20 carbon atoms.

The composition may further comprise additives for improving certain properties of the PHA composition, such as nucleating agents, plasticizers, dyes, UV absorbers, stabilizers, antioxidants, fillers, flame retardants, lubricants, antiblocking agents, release agents or process-facilitating additives commonly referred to as "processing aids".

The composition according to the invention can be manufactured by mixing the various constituents by the conventional means for using the thermoplastics, such as, for example, extrusion or kneading. It is possible to use internal mixers with blades or rotors, an external mixer, co-rotating or counter-rotating single-screw, twin-screw extruders. Preferably, the composition is carried out at a temperature greater than or equal to the glass transition temperature of the PHA, or even above. The composition may be carried out for example at a temperature in the range of 160 ° C to 260 ° C.

According to a preferred method of the invention, a step of mixing a shock modifier in the PHA is carried out, said impact modifier being a mixture comprising (A), (B) and the optional (C).

Since the compound (A) is powdery, the process for manufacturing the PHA composition is facilitated by mixing (A) with (B) and the optional (C), the impact modifier thus obtained then being in the form of granules which are more easily manipulated during the PHA transformation process.

Another object of the invention is a part or an object, such as a package, a film or a sheet, made from the composition according to the invention. To manufacture this part or this object, it is possible to use the known molding techniques, such as a press, an injected press or the known blow molding extrusion techniques known as "blow molding". The films or sheets can also be made by the techniques of extrusion of flat film ("cast film"), blown film extrusion ("blown film") or calendering. The method of manufacturing this part may also include an annealing step to crystallize the PHA and thus improve its mechanical properties.

Examples of compositions will now be described in the examples which follow; these examples are given for illustrative purposes and in no way limit the scope of the claimed invention.

Examples

For carrying out examples of the composition and structures according to the invention, the following products were used: (a1): core-shell core-shell compound based on butadiene, methyl methacrylate, ethyl acrylate and butyl acrylate . (a2): core-shell compound based on butyl acrylate and methyl methacrylate. (a3): core-shell compound comprising acrylonitrile, butadiene and styrene. (b): ethylene-methyl acrylate-glycidyl methacrylate copolymer comprising, by weight, 25% of acrylate and 8% of glycidyl methacrylate (Lotader® AX 8900) whose melting point measured by DSC (ISO 11357-03) is 65 ° C. (c): ethylene-butyl acrylate copolymer comprising by weight 30% of acrylate (Lotryl® 30BA02) whose melting point measured by DSC (ISO 11357-03) is 78 ° C. (d): Poly lactic acid 2002D marketed by NatureWorks®.

The compositions according to the invention (4) and (5) and comparative (1) (2) and (3) comprise the constituents (a), (b1), (b2), (b3), (c) and (d). ) in the proportions of Table 1.

The compositions (1) to (5) were prepared in a single step. The mixture of constituents in the ratio of Table 1 is made by extrusion.

The extrusion is carried out in a twin-screw co-rotating extruder whose diameter is 16 mm and the L / D ratio is 25 (Haake PTW16 / 25). The maximum temperature of the mixture is 240 ° C.

The constituents (b1), (b2) and (b3) being powders and the aforementioned extruder being equipped with only one metering device, it is necessary to grind the constituents (a) and (d) by cryomilling until obtaining a fine powder so as to obtain a correct dosage of the constituents in the extruder for the preparation of the mixtures (2) to (5).

The compositions are then injected at 200 ° C. into a mold controlled at 30 ° C. using an Krauss Maffei 60-210 B1 injection press.

The properties "Choc Charpy notched" are measured according to the ISO 179: 2000 standard after annealing the samples 1 hour at 110 ° C to crystallize the poly lactic acid. The higher the charpy impact value, the better the impact resistance. These properties were measured at room temperature (23 ° C) and cold (0 ° C and / or -40 ° C). The values obtained are reported in Table 2.

The "Notched Shock Charpy" properties are also measured at room temperature according to ISO 179: 2000 without annealing. The values obtained are reported in Table 3.

Table 1 Compositions Percentage Percentage Percentage mass by mass (a) / (b) / (c) / ((a) + (b) + (c) + (d)) ((a) + (b) + (c) + (d)) ((a) + (b) + (c) + (d)) (1) 0% 2% 8% (2) a3: 10% 0% 0% (3) a1: 10% 0 % 0% (4) a1: 7% 3% 0% (5) a1: 5% 5% 0% (6) a2: 7.5% 7.5% 0% (7) a2: 3% 3% 0 % Table 2 Compositions Choc Charpy Choc Charpy Choc Charpy 23 ° C OC -40 ° C (1) 11 Not measured 6 (2) 13.5 Not measured 6.5 (3) 38 15 9 (4) 68 39 10 (5) 54 39 10 (6) 62 Not measured Not measured (7) 20 Not measured Not measured Table 3 (without annealing) Compositions Choc Charpy (1) 5 (2) 9 (3) 14 (4) 27 (6) 50 Compositions prepared according to US Pat. The invention has improved impact properties compared with those obtained from the prior art.

Claims (15)

Revendications1. A hydroxyalkanoic polyacid (PHA) composition further comprising: (A) an elastomeric core-shell compound; (B) and an olefinic copolymer comprising an ethylenic monomer carrying an epoxy function. 2. Composition according to Claim 1, characterized in that the epoxy functional ethylenic monomer is glycidyl (meth) acrylate. 3. Composition according to one of the preceding claims characterized in that (B) is a copolymer of ethylene, glycidyl methacrylate and optionally alkyl (meth) acrylate whose alkyl chain comprises from 1 to 30 atoms of carbon. 4. Composition according to one of the preceding claims further comprising an additional olefinic polymer (C) other olefinic copolymers comprising an ethylene monomer bearing an epoxy function. 5. Composition according to the preceding claim wherein the additional olefinic polymer (C) is a copolymer of ethylene and an alkyl (meth) acrylate, a copolymer of ethylene and a vinyl ester of carboxylic acid. a copolymer of ethylene and a (meth) acrylic acid or an ionomer, preferably a copolymer of ethylene and of an alkyl acrylate having an alkyl chain ranging from 1 to 20, for example methyl acrylate ethylene acrylate or n-butyl acrylate. 30 6. Composition according to one of claims 4 or 5 wherein the mass ratio (B) / (C) is in the range of 90/10 to 10/90, preferably 75/25 to 40/60. 7. Composition according to one of the preceding claims wherein the weight ratio (A) / ((B) + (C) optional) is in the range from 90/10 to 10/90, for example 85/15 to 40/60, advantageously from 80/20 to 50/50 and preferentially from 75/25 to 60/40. 8. Composition according to one of the preceding claims wherein the amount of ((A) + (B) + (C) optional) is in the range of 1 to 30% by weight of the total composition, preferably 2 at 15%, preferably 3 to 9%. 9. Composition according to one of the preceding claims wherein the amount, in polymerized form, of ethylenic monomer comprising an epoxy function is in the range of 0.01% to 2%, preferably 0.02 to 1% preferentially. from 0.03 to 0.7% by weight of the total composition. 10. Composition according to one of the preceding claims wherein the core polymer of the heart-shell compound (A) has a glass transition temperature of less than 20 ° C and the polymer of the bark has a glass transition temperature greater than 20. ° C. 11. Composition according to one of the preceding claims wherein the amount of core mass is in the range of 60 to 95% of the total mass of the core-shell compound. 12. Composition according to one of the preceding claims wherein the size of the core-shell compounds is between 50 and 600nm. 13. Composition according to one of the preceding claims wherein the PHA is selected from poly lactic acid (PLA) and poly glycolic acid (PGA). 14. A process for the preparation of the composition according to any one of the preceding claims wherein the mixture of PHA, (A), (B), (C) and optionally additives such as is prepared by kneading or extrusion. a nucleating agent. 15. Process for the preparation of the composition according to one of claims 1 to 13, in which is carried out: in a first step a mixture of (A), (B) and (C) optionally to form an impact modifier then, in a second step, mixing the impact modifier resulting from the first step with the PHA. 18. Part or object, such as a package comprising a composition according to one of claims 1 to 13 or a composition resulting from the process according to claim 14 or 15. 19. A method of manufacturing a part or an object according to claim 16 comprising a step of shaping the composition, for example by injection, pressing or calendering, said part or said object possibly undergoing an annealing step.