Reinforced branched poly(hydroxy acid) compositions

Abstract

The present invention relates to branched poly(hydroxy acid) polymers with an improved balance of mechanical properties.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 236,825, filed August 25, 2021, the entire contents of which are incorporated herein by reference for all purposes.

[0002] The present invention relates to poly(hydroxy acid) (PHA) compositions, specifically poly(glycolic acid) (PGA), endowed with high elastic modulus and high ductility. [Background technology]

[0003] Poly(glycolic acid) (PGA) is a polymer of high interest for a multitude of applications in consumer, oil and gas, and biomedical applications due to its excellent mechanical and barrier properties combined with biodegradability.

[0004] In oil and gas applications, PGA is typically used as downhole tools or downhole tool components during drilling and fracking operations. The strength and degradability allow the material to play a temporary role in the process and degrade away without the need for drilling out.

[0005] However, one of the major drawbacks of PGA is its low ductility, thus limiting its possible use in these demanding applications.

[0006] EP 3088657 A1 (Kureha Corporation) discloses a downhole tool or downhole tool component having sufficient mechanical strength under severe conditions and high impact resistance, said downhole tool or downhole tool component being made of a composition comprising a degradable resin, preferably selected from the group consisting of PGA, PLA, and glycolic acid-lactic acid copolymer (PGLA), and a toughness improver. The composition may further comprise a chain extender, in which case the composition contains 60-98.8% by mass of the degradable resin, 1-37% by mass of the toughness improver, and 0.2-3% by mass of the chain extender, the sum of the degradable resin, the toughness improver, and the chain extender being 100% by mass. The chain extender may be an oxazoline compound, an isocyanate compound, a carbodiimide compound, a carbodiimide-modified isocyanate compound, a fatty acid bisamide compound, an alkyl-substituted fatty acid monoamide compound, a mono- to trifunctional glycidyl-modified compound having a triazine skeleton, an epoxy compound, an acid anhydride, an oxazine compound, a ketene compound, etc.; oxazoline compounds and isocyanate compounds are preferred. EP 3088657 A1 does not disclose a composition containing a branched PGA or a branched PGA copolymer.

[0007] WO2020087205A1 (Pujing Chemical Ind Co Ltd) relates to polyglycolide copolymers comprising blocks of PGA with a length of 1-1500 units and blocks of aliphatic and / or aromatic polymers, bound together by covalent bonds of different nature. The copolymers can be prepared by ring-opening polymerizing glycolide and extruding / granulating it with additives having isocyanates, acid chlorides, oxazolyls, oxazolines, acid anhydrides, epoxy groups or amine groups. The structure of the polyglycolide blocks is believed to be linear.

[0008] It has now been discovered that the ductility and tensile elongation at break of certain branched poly(hydroxy acid) polymers can be successfully increased while maintaining the high tensile and flexural moduli of the unmodified resin by the incorporation of small amounts of select chain extenders. The resulting compositions have a good balance of mechanical and solubility properties that make them advantageous over the linear chain extended polymers of the prior art. Summary of the Invention

[0009] The object of the present invention is a composition comprising a branched poly(hydroxy acid) polymer, hereinafter [polymer (HAP)], and 0.01 to less than 1.00 wt. % of a chain extender [agent CE] having epoxy functional groups and a number average functionality of 2 or greater.

[0010] The branched poly(hydroxy acid) polymers are (i) at least one hydroxy acid having only one hydroxyl group and only one carboxylic acid group [hydroxy acid (A)]; (ii) optionally at least one carboxylic acid [acid (C)] having one or two carboxylic acid groups and no hydroxyl groups; (iii) - a compound containing at least one epoxy functional group, preferably a compound selected from the group consisting of epoxysilanes and polyepoxides; - a mixture comprising at least one polyol containing at least three hydroxyl groups and no carboxylic acid groups [polyol (H)], and at least one polyacid containing at least two carboxylic acid groups and no hydroxyl groups [polyacid (O)]; and a mixture comprising at least one polyol containing at least three hydroxyl groups and no carboxylic acid groups [polyol (H)] and at least one alcohol containing one or two hydroxyl groups and no carboxylic acid groups [alcohol (AO)] at least one polyfunctional reactant [reactant (F)] different from the hydroxy acid (A) and the acid (C) selected from the group consisting of: It is obtained by the polycondensation reaction of a monomer mixture containing

[0011] A further object of the invention is a chain extended polymer [polymer (CEHAP)] comprising a backbone of a branched poly(hydroxy acid) polymer, polymer (HAP), covalently bonded to units derived from a chain extender, agent (CE), the amount of units derived from agent (CE) being 0.01-1.00 wt % based on the total weight of polymer (CEHAP).

[0012] The chain-extended polymer (CEHAP) is typically obtained by reacting the polymer (HAP) with the agent (CE). The reaction is typically carried out in the melt phase of the polymer (HAP). Typically, the reaction is carried out in an extruder.

[0013] The chain extended polymer (CEHAP) can be formed into articles such as bottles, articles for hydrocarbon resource recovery, such as downhole tools or downhole tool components, packaging films, sanitary products, disposable pods, structural components for electronic applications, or biomedical articles. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] For the purposes of this discussion: - the use of parentheses around symbols or numbers identifying compounds, chemical formulae or parts of formulae has the sole purpose of better distinguishing those symbols or numbers from the rest of the text, and therefore said parentheses may also be omitted; - Where numerical ranges are given, the endpoints of the range are included.

[0015] Branched poly(hydroxy acid) polymer, polymer (HAP) Hydroxy Acid (A) Any hydroxy acid that can be polycondensed, i.e., can form a polymer by condensation, i.e., chain addition of monomers with elimination of water, can be used as hydroxy acid (A). Examples include glycolic acid, lactic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid, 5-hydroxyvaleric acid, 6-hydroxycaproic acid. In general, hydroxy acids with primary alcohols are preferred as they are more reactive.

[0016] Preferably, the hydroxy acid (A) is selected from the group consisting of glycolic acid, lactic acid (L or D isomer, either in a racemic mixture or as a single isomer), and mixtures thereof. Glycolic acid is particularly preferred.

[0017] The hydroxy acid (A) may consist of glycolic acid. Alternatively, the hydroxy acid (A) may comprise glycolic acid and at least one hydroxy acid (A) different from glycolic acid. In said alternative variant, glycolic acid is preferably at least 50 mol%, preferably at least 70 mol%, or even at least 95 mol% of the total amount of hydroxy acids (A). When present, the amount of hydroxy acids (A) different from glycolic acid is at most 5 mol%, generally at most 4 mol%, preferably at most 3 mol%, relative to the sum of the moles of glycolic acid and hydroxy acids (A); and / or said amount can be as low as 0.1 mol%.

[0018] Acid (C) The acid (C) is selected from among carboxylic acids having one or two carboxylic acid groups and not containing a hydroxyl group. It is generally understood that better results are obtained with an acid (C) having a total number of carbon atoms of at least 4, preferably at least 5, more preferably at least 6. In general, the acid (C) has from 4 to 36 carbon atoms, preferably from 6 to 24 carbon atoms.

[0019] Among the carboxylic acids having one carboxylic acid group which can be advantageously used as acid (C) are, inter alia, caprylic acid [CH3(CH2)6-COOH], capric acid [CH3(CH2)8-COOH], undecanoic acid [CH3(CH2)9-COOH], dodecanoic acid or lauric acid [CH3(CH2) 10 -COOH], tridecanoic acid [CH3(CH2) 11 -COOH], tetradecanoic acid or myristic acid [CH3(CH2) 12 -COOH], pentadecanoic acid [CH3(CH2) 13 -COOH], hexadecanoic acid or palmitic acid [CH3(CH2) 14 -COOH], octadecanoic acid or stearic acid [CH3(CH2) 16 -COOH], arachidic acid [CH3(CH2) 18 -COOH], behenic acid [CH3(CH2) 20 --COOH]. A fatty acid (C) which has been shown to give particularly good results is stearic acid, which is why stearic acid is particularly preferred.

[0020] When the acid (C) is an aromatic monocarboxylic acid, it is advantageously selected from the group consisting of benzoic acid, naphthoic acid and phenylacetic acid.

[0021] Among the dicarboxylic acids which can be advantageously used as acid (C) are succinic acid [HOOC-(CH2)2-COOH], glutaric acid [HOOC-(CH2)3-COOH], 2,2-dimethyl-glutaric acid [HOOC-C(CH3)2-(CH2)2-COOH], adipic acid [HOOC-(CH2)4-COOH], 2,4,4-trimethyl-adipic acid [HOOC-CH(CH3)-CH2-C(CH3)2-CH2-COOH], pimelic acid [HOOC-(CH2) 5- COOH], suberic acid [HOOC-(CH2)6-COOH], azelaic acid [HOOC-(CH2)7-COOH], sebacic acid [HOOC-(CH2)8-COOH], undecanedioic acid [HOOC-(CH2)9-COOH], dodecanedioic acid [HOOC-(CH2 10-COOH], tetradodecanedioic acid [HOOC-(CH2) 11 -COOH], octadodecane diacid [HOOC-(CH2) 16 --COOH] can be mentioned.

[0022] Multifunctional Reactant (F) Compounds containing at least one epoxy functional group Notable non-limiting examples of suitable compounds containing at least one epoxy functional group are selected from the group consisting of epoxy silanes, in particular glycidyloxypropyltrimethoxysilane, or polyepoxides, among which mention may be made of bisphenol A diglycidyl ether (BADGE) or epoxidized oils such as epoxidized soybean oil or epoxidized linseed oil.

[0023] A mixture comprising at least one polyol (H) and at least one polyacid (O). Polyol (H) The choice of polyol (H) is not particularly limited: any polyol containing at least three hydroxyl groups and no carboxylic acid groups can be used for the preparation of the branched poly(hydroxy acid).

[0024] The polyol (H) is In particular, glycerol, trimethylolpropane, trimethylolbutane, 2,3-di(2'-hydroxyethyl)-cyclohexan-1-ol, hexane-1,2,6-triol, 1,1,1-tris(hydroxymethyl)ethane, 3-(2'-hydroxyethoxy)propane-1,2-diol, 3-(2'-hydroxypropoxy)-propane-1,2-diol, 2-(2'-hydroxyethoxy)-hexane-1,2-diol, 6-(2'-hydroxypropoxy)-hexane-1,2-diol, 1 , a triol selected from the group consisting of 1,1-tris-[(2'-hydroxyethoxy)-methylethane, 1,1,1-tris-[(2'-hydroxypropoxy)-methyl-propane, 1,1,1-tris-(4'-hydroxyphenyl)ethane, 1,1,1-tris-(hydroxyphenyl)-propane, 1,1,5-tris-(hydroxyphenyl)-3-methylpentane, trimethylolpropane ethoxylate, trimethylolpropane propoxylate, and tris(hydroxymethyl)aminomethane; - tetraols, in particular selected from the group consisting of diglycerol, di(trimethylolpropane), pentaerythritol, 1,1,4-tris-(dihydroxyphenyl)-butane; - polyols containing five hydroxyl groups, in particular triglycerol; - polyols containing six hydroxyl groups, in particular dipentaerythritol; and - Polyols containing eight hydroxyl groups, especially tripentaerythritol The compound may be selected from the group consisting of:

[0025] Preferred polyols (H) are triols and tetraols. A polyol (H) which has been found to give particularly good results within the scope of the present invention is trimethylolpropane.

[0026] Polyacid (O) Polyacid (O) can be any polyacid containing at least two carboxylic acid groups and no hydroxyl groups. Polyacid (O) is different from acid (C), if present.

[0027] The polyacid (O) comprises at least two carboxylic acid groups, in particular 2, 3 or 4 carboxylic acid groups.

[0028] The polyacid (O) may be chosen from aliphatic, cycloaliphatic and aromatic polycarboxylic acids.

[0029] Examples of aliphatic polycarboxylic acids are propane 1,2,3-tricarboxylic acid (also known as tricarballylic acid); ethane-1,1,2,2 tetracarboxylic acid; butane-1,2,3,4 tetracarboxylic acid; pentane-1,2,4,5-tetracarboxylic acid. Among them, butane-1,2,3,4 tetracarboxylic acid is preferred.

[0030] Examples of alicyclic polycarboxylic acids are 1,2,3,4-cyclobutanetetracarboxylic acid; 2,2,6,6-tetra-(carboxyethyl)cyclohexanone; (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid; cyclopentane-1,2,3,4 tetracarboxylic acid; cyclohexane-1,2,4,5 tetracarboxylic acid; cyclohexane-2,3,5,6 tetracarboxylic acid; 3-ethylcyclohexane-1,2,4,5 tetracarboxylic acid; 1-methyl-3-ethylcyclohexane-3-(1,2)5,6 tetracarboxylic acid; 1-ethylcyclohexane-1-(1,2),3,4 tetracarboxylic acid; 1-propylcyclohexane-1-(2,3),3,4 tetracarboxylic acid; 1,3-dipropylcyclohexane-1-(2,3),3-(2,3) tetracarboxylic acid; and dicyclohexyl-3,4,3',4' tetracarboxylic acid.

[0031] Examples of aromatic polycarboxylic acids are phthalic acid, such as isophthalic acid and terephthalic acid, 2,5-pyridinedicarboxylic acid, 2,4-pyridinedicarboxylic acid, 3,5-pyridinedicarboxylic acid, 2,2-bis(4-carboxyphenyl)propane, bis(4-carboxyphenyl)methane, 2,2-bis(4-carboxyphenyl)hexafluoropropane, 2,2-bis(4-carboxyphenyl)ketone, 4,4'-bis(4-carboxyphenyl)sulfone, 2,2-bis(3-carboxyphenyl)propane, bis(3-carboxyphenyl)methane, 2,2-bis(3-carboxyphenyl)hexafluoropropane, 2,2-bis(3-carboxyphenyl)ketone, bis(3-carboxyphenoxy)benzene, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, and other naphthalenedicarboxylic acids.

[0032] Among the aromatic carboxylic acids having three or more carboxylic acid groups, pyromellitic acid (1,2,4,5-benzenetetracarboxylic acid); trimesic acid (1,3,5-benzenetricarboxylic acid); trimellitic acid (1,3,4-benzenetricarboxylic acid); benzophenone-3,3',4,4'-tetracarboxylic acid; tetrahydrofuran-2,3,4,5-tetracarboxylic acid; 4,4'-(hexafluoroisopropylidene)diphthalic acid; 4,4'-oxydiphthalic anhydride. 4,4'-(4,4'-isopropylidenediphenoxy)bis(phthalic acid);3,3',4,4'-biphenyltetracarboxylic acid;2,3,3',4'-biphenyltetracarboxylic acid;2,2',3,3'-biphenyltetracarboxylic acid;1,2,5,6-naphthalenetetracarboxylic acid;2,3,6,7-naphthalenetetracarboxylic acid;Perylene-3,4,9,10tetracarboxylic acid;Propane-2,2-bis(3,4-dicarboxyphenyl) acid;Ethane 1 ,1-Bis(2,3-dicarboxyphenyl) acid;Ethane 1,1-bis(3,4-dicarboxyphenyl) acid;Phenanthrene-1,8,9,10-tetracarboxylic acid;Tetrahydrofuran-2,3,4,5-tetracarboxylic acid;3,3',4,4'-Benzophenonetetracarboxylic acid;2,2',3,3'-Benzophenonetetracarboxylic acid;2,3,5,6-Pyridinetetracarboxylic acid;3,3',4,4'-Tetraphenylsilanetetracarboxylic acid;2,2 2,2-bis(3,4-dicarboxyphenyl)sulfonic acid; 4,4'-(hexafluoroisopropylidene)diphthalic acid; 3,3',4,4'-diphenylsulfonetetracarboxylic acid; ethylene glycol bistrimellitic acid; hydroquinone diphthalic acid; pyrazine-2,3,5,6-tetracarboxylic acid; thiophene-2,3,4,5-tetracarboxylic acid may be mentioned.

[0033] Polyacids (O) which have proved to give particularly good results within the scope of the invention are phthalic acid, in particular isophthalic acid, tricarballylic acid, 1,2,4,5-benzenetetracarboxylic acid and butane-1,2,3,4 tetracarboxylic acid. Tricarballylic acid and isophthalic acid are particularly preferred.

[0034] A mixture comprising at least one polyol (H) and at least one alcohol (AO). The polyol (H) is as detailed above.

[0035] Alcohol (AO) The alcohol (AO) can be a monoalcohol (MO) containing one hydroxyl group, a diol (D) containing two hydroxyl groups, or a mixture of a monoalcohol (MO) and a diol (D).

[0036] When the alcohol (AO) is a monoalcohol (MO), it may be chosen from an aliphatic or aromatic monoalcohol.

[0037] The monoalcohols (MO) are advantageously characterized by a boiling point at atmospheric pressure of at least 90°C, preferably at least 100°C, more preferably at least 125°C, most preferably at least 150°C.

[0038] The aliphatic monoalcohol (MO) is advantageously of the formula: R Hm -OH (In the formula, R Hm is a monovalent aliphatic radical having 1 or 2 or more carbon atoms, particularly 3 or more carbon atoms. It is an aliphatic monoalcohol.

[0039] It is generally understood that better results are obtained with long chain aliphatic monoalcohols, i.e. aliphatic monoalcohols (MO) whose total number of carbon atoms is advantageously at least 6. The aliphatic monoalcohols (MO) preferably have from 6 to 36 carbon atoms, more preferably from 6 to 24 carbon atoms.

[0040] Among the aliphatic monoalcohols (MO) that can be advantageously used in the present invention, there are in particular 1-hexanol [CH3(CH2)5-OH], 1-dodecanol [CH3(CH2)11 -OH], 1-hexadecanol or cetyl alcohol [CH3(CH2) 15 -OH], 1-octadecanol or stearyl alcohol CH3(CH2) 17 -OH], arachidyl alcohol CH3(CH2) 18 -OH], 1-docosanol, or behenyl alcohol [CH3(CH2) 21 --OH], cyclohexanol and menthol.

[0041] When the monoalcohol (MO) is an aromatic monoalcohol, it is advantageously selected from the group consisting of phenol, cresol, naphthol, benzyl alcohol, 2-phenylethanol and 3-phenylpropanol.

[0042] The monoalcohol (MO) is preferably selected from the group consisting of dodecanol, benzyl alcohol, menthol and mixtures thereof.

[0043] When the alcohol (AO) is a diol (D), the diol (D) is advantageously characterized by a boiling point at atmospheric pressure of at least 100°C, preferably of at least 150°C, more preferably of at least 200°C and most preferably of at least 230°C.

[0044] Non-limiting examples of suitable diols (D) are, inter alia, ethylene glycol, 2,2-dimethylpropane-1,3-diol, pentane-1,2-diol, pentane-1,5-diol, hexane-1,2-diol, heptane-1,2-diol, diethylene glycol, hexane-1,6-diol, heptane-1,7-diol, 1,4-cyclohexanediol, cis 1,2-cyclohexanediol, trans 1,2-cyclohexanediol, polyether polyol diol Dianol® 220, 1,4-cyclohexanedimethanol, isosorbide, isoidide, dodecane 1,12 diol, and mixtures thereof.

[0045] The diol (D) is preferably selected from the group consisting of diethylene glycol, 1,4-cyclohexanedimethanol, isosorbide, isoidide, dodecane 1,12-diol, and mixtures thereof.

[0046] Diol (D) is more preferably selected from the group consisting of diethylene glycol, 1,4-cyclohexanedimethanol, and mixtures thereof.

[0047] A diol (D) which has been shown to give particularly good results is 1,4-cyclohexanedimethanol, which is therefore most particularly preferred, with the cis / trans isomer mixture of 1,4-cyclohexanedimethanol (CAS number 105-08-8) being very particularly preferred.

[0048] The alcohol (AO) is preferably selected from the group consisting of diethylene glycol, 1,4-cyclohexanedimethanol, isosorbide, isoidide, dodecane 1,12-diol, dodecanol, benzyl alcohol, menthol and mixtures thereof.

[0049] The branched poly(hydroxy acid) polymers used in the compositions of the present invention are (i) at least one hydroxy acid having only one hydroxyl group and only one carboxylic acid group [hydroxy acid (A)]; (ii) optionally at least one carboxylic acid [acid (C)] having one or two carboxylic acid groups and no hydroxyl groups; (iii) at least one multifunctional reactant [reactant (F)] as detailed above; It is obtained by the polycondensation reaction of a monomer mixture containing

[0050] The expression "branched polymer" is used herein in the sense given by IUPAC, i.e. to identify a polymer whose molecules are branched. In this context, the branches are introduced into the polymer chain by the presence of at least one multifunctional reactant, reactant (F).

[0051] In a first embodiment of the present invention, the branched poly(hydroxy acid) polymers may be selected from among those polymers comprising repeat units derived from the polycondensation reaction of a monomer mixture comprising at least one hydroxy acid (A) and at least one reactant (F) selected from the group consisting of compounds containing at least one epoxy functional group, preferably selected from the group consisting of compounds selected from the group consisting of epoxy silanes and polyepoxides.

[0052] The polymers of the first embodiment are, for example, those described in WO 2010 / 112602 A1 and can be prepared according to the methods described therein.

[0053] In a second embodiment of the present invention, the branched poly(hydroxy acid) polymers are selected from among those polymers comprising repeat units derived from the polycondensation reaction of a monomer mixture comprising at least one hydroxy acid (A) and at least one reactant (F) selected from a mixture comprising at least one polyol (H) having at least three hydroxyl groups and at least one polyacid (O) having at least three carboxylic acid groups.

[0054] In this second embodiment, the hydroxy acid (A) is preferably chosen from glycolic acid, lactic acid and mixtures thereof, more preferably, the hydroxy acid (A) is glycolic acid.

[0055] Advantageously, the mixture comprising at least one polyol (H) and at least one polyacid (O) is chosen from a mixture of pentaerythritol and butanetetracarboxylic acid or a mixture of trimethylolpropane and tricarballylic acid.

[0056] The polymers of the second embodiment are, for example, those described in WO 2010 / 112602 A1 and can be prepared according to the methods described therein.

[0057] In a third embodiment of the invention, the branched poly(hydroxy acid) polymers may be selected from among those polymers obtained from the polycondensation reaction of a monomer mixture comprising at least one hydroxy acid (A), optionally at least one acid (C), and at least one reactant (F) selected from a mixture comprising at least one polyol (H) containing at least three hydroxyl groups and at least one polyacid (O) containing at least three carboxylic acid groups. In particular, the branched poly(hydroxy acid) polymers may be selected from among those polymers in which the amount of acid (C) is such that the number of its carboxylic acid groups is comprised between 0.0001 and 0.010% relative to the number of hydroxyl groups of the hydroxy acid (A).

[0058] Preferably, the hydroxy acid (A) is selected from glycolic acid, lactic acid and mixtures thereof, more preferably, the hydroxy acid (A) is glycolic acid.

[0059] The polyol (H) is typically chosen from among the triols (especially trimethylolpropane) and the tetraols (especially pentaerythritol). A polyol (H) which has been found to give particularly good results is trimethylolpropane.

[0060] Polyacids (O) which have been found to give particularly good results are tricarballylic acid, 1,2,4,5-benzenetetracarboxylic acid and butane-1,2,3,4 tetracarboxylic acid, with tricarballylic acid being particularly preferred.

[0061] Generally, the amounts of polyacid (O) and polyol (H) in the branched poly(hydroxy acid) polymer of the third embodiment, expressed as moles per mole of hydroxy acid (A), are substantially similar. The molar ratio of polyacid (O):polyol (H) is in the range of 1.5:1 to 0.5:1, preferably in the range of 1.25:1 to 0.75:1, more preferably in the range of 1.10:1 to 0.9:1.

[0062] If present, the amount of acid (C) is such that the number of its carboxylic acid groups is comprised between 0.0001 and 0.010% relative to the number of hydroxyl groups of hydroxy acid (A).Preferably, said amount is such that the number of carboxylic acid groups of said acid (C) is at least 0.0005%, preferably at least 0.001% relative to the number of hydroxyl groups of hydroxy acid (A) and / or at most 0.010%, preferably at most 0.008%, most preferably at most 0.007% and even more preferably at most 0.006% relative to the number of hydroxyl groups of hydroxy acid (A).

[0063] The acid (C) is preferably a monocarboxylic acid. Stearic acid is particularly preferred.

[0064] The polymer of the third embodiment is, for example, one described in WO2016173640A1 and can be prepared according to the methods described therein.

[0065] In a fourth embodiment of the invention, the branched poly(hydroxy acid) polymers may be selected from among those polymers obtained from the polycondensation reaction of a monomer mixture comprising glycolic acid; optionally at least one hydroxy acid (A) different from glycolic acid, in an amount of at most 5 mol % relative to the sum of the moles of glycolic acid and hydroxy acid (A); optionally at least one acid (C) having one carboxylic acid group; and at least one reactant (F) selected from a mixture comprising at least one polyol (H) containing at least three hydroxyl groups and at least one polyacid (O) selected from aromatic acids containing two aromatic carboxylic acid groups. In particular, the amount of polyol (H) is such that the number of its hydroxyl groups is comprised between 0.050 and 1.200% relative to the total number of carboxyl groups of glycolic acid and, if present, of hydroxy acid (A); the amount of polyacid (O) is such that the number of its carboxylic acid groups is comprised between 0.050 and 0.750% relative to the total number of hydroxyl groups of glycolic acid and, if present, of hydroxy acid (A); and the amount of acid (C), if present, is such that the number of its carboxylic acid groups is comprised between 0.0001 and 0.010% relative to the total number of hydroxyl groups of glycolic acid and, if present, of hydroxy acid (A).

[0066] The polyol (H) is typically chosen from among triols (especially trimethylolpropane) and tetraols (especially pentaerythritol). Preferably, the polyol (H) is trimethylolpropane.

[0067] Non-limiting examples of suitable polyacids (O) containing two aromatic carboxylic acid groups include phthalic acid, such as isophthalic acid and terephthalic acid, 2,5-pyridinedicarboxylic acid, 2,4-pyridinedicarboxylic acid, 3,5-pyridinedicarboxylic acid, 2,2-bis(4-carboxyphenyl)propane, bis(4-carboxyphenyl)methane, 2,2-bis(4-carboxyphenyl)hexafluoropropane, 2,2-bis(4-carboxyphenyl)ketone, 4,4'-bis(4-carboxyphenyl)sulfonyl ether ... Examples of suitable phthalic acids include phthalic acid, ...

[0068] The acid (C) is a monocarboxylic acid. Stearic acid is particularly preferred.

[0069] The polymer of the fourth embodiment is, for example, one described in WO2018115008A1 and can be prepared according to the methods described therein.

[0070] In a fifth embodiment of the invention, the branched poly(hydroxy acid) polymer is selected from among those polymers obtained from the polycondensation reaction of a monomer mixture comprising glycolic acid; optionally at least one hydroxy acid (A) different from glycolic acid, where the molar amount of hydroxy acid (A) is at most 5 mol % relative to the sum of the moles of glycolic acid and hydroxy acid (A); optionally at least one acid (C), said acid (C) having one carboxylic acid group; optionally at least one polyacid (O); and at least one reactant (F) selected from a mixture comprising at least one polyol (H) and at least one alcohol (AO).

[0071] Preferably, the branched poly(hydroxy acid) polymer is obtained from a polycondensation reaction of a monomer mixture consisting of glycolic acid; optionally at least one hydroxy acid (A) different from glycolic acid, where the molar amount of hydroxy acid (A) is at most 5 mol % relative to the sum of the moles of glycolic acid and hydroxy acid (A); at least one polyol (H); and at least one alcohol (AO), preferably at least one diol (D).

[0072] Most preferably, the branched poly(hydroxy acid) polymer is obtained from the polycondensation reaction of a monomer mixture consisting of glycolic acid; optionally at least one hydroxy acid (A) different from glycolic acid, where the molar amount of hydroxy acid (A) is at most 5 mol % relative to the sum of the moles of glycolic acid and hydroxy acid (A); at least one polyol (H); and at least one diol (D).

[0073] The hydroxy acid (A) is advantageously selected from the group consisting of lactic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxyvaleric acid, 5-hydroxyvaleric acid, 6-hydroxycaproic acid, and is preferably lactic acid.

[0074] Preferred polyols (H) are the triols, as detailed above, in particular those selected from the group consisting of glycerol, trimethylolpropane and trimethylolbutane, and tetraols, in particular pentaerythritol.

[0075] A polyol (H) which has been found to give particularly good results is trimethylolpropane.

[0076] The polyol (H) is used in an amount such that the number of its hydroxyl groups is advantageously comprised between 0.050 and 1.200% relative to the total number of carboxyl groups of the glycolic acid and, if present, of the hydroxy acid (A). Advantageously, the polyol (H) is present in an amount such that the number of its hydroxyl groups is at least 0.075%, even at least 0.100%, preferably at least 0.120%, relative to the total number of carboxyl groups of the glycolic acid and, if present, of the hydroxy acid (A). The polyol (H) is present in an amount such that the number of its hydroxyl groups is at most 1.000%, even at most 0.750%, preferably at most 0.600%, relative to the total number of carboxyl groups of the glycolic acid and, if present, of the hydroxy acid (A).

[0077] When the alcohol (AO) is a monoalcohol (MO), it is preferably selected from the group consisting of dodecanol, benzyl alcohol, menthol and mixtures thereof.

[0078] When the alcohol (AO) is a diol (D), the diol (D) is preferably selected from the group consisting of diethylene glycol, 1,4-cyclohexanedimethanol, isosorbide, isoidide, dodecane 1,12-diol and mixtures thereof, more preferably selected from the group consisting of diethylene glycol, 1,4-cyclohexanedimethanol and mixtures thereof.

[0079] A diol (D) which has been shown to give particularly good results is 1,4-cyclohexanedimethanol, which is therefore most particularly preferred, with the cis / trans isomer mixture of 1,4-cyclohexanedimethanol (CAS number 105-08-8) being very particularly preferred.

[0080] The alcohol (AO) is preferably selected from diethylene glycol, 1,4-cyclohexanedimethanol, isosorbide, isoidide, dodecane 1,12-diol, dodecanol, benzyl alcohol, menthol and mixtures thereof.

[0081] The alcohol (AO) is more preferably a diol (D), which is preferably characterized by a boiling point at atmospheric pressure of at least 100° C. and / or which is preferably used in the amounts as specified below.

[0082] The alcohol (AO) is advantageously used in an amount such that the number of its hydroxyl groups is comprised between 0.010 and 1.200% relative to the total number of carboxylic acid groups of the glycolic acid and, if present, of the hydroxy acid (A).

[0083] The alcohol (AO) is used in an amount such that the number of its hydroxyl groups is advantageously at least 0.010%, preferably at least 0.050%, more preferably at least 0.080%, most preferably at least 0.100%, and / or advantageously at most 1.200%, even at most 1.000%, preferably at most 0.750%, more preferably at most 0.700%, most preferably at most 0.650%, relative to the total number of carboxylic acid groups of glycolic acid and, if present, of hydroxy acids (A).

[0084] Advantageously, the alcohol (AO) is in such a quantity that the number of its hydroxyl groups is between 0.010 and 0.650% relative to the total number of carboxylic acid groups of the glycolic acid and of the hydroxy acid (A).

[0085] The polyols (H) and the alcohols (AO) are used in amounts such that the total number of moles of their hydroxyl groups divided by the total number of moles of carboxylic acid groups of glycolic acid and, if present, of hydroxy acids (A) is advantageously comprised between 0.0 and 1.0%, preferably between 0.1 and 1.0% and more preferably between 0.3 and 0.9%.

[0086] The acid (C) is a monocarboxylic acid. Among the aliphatic monoacids, stearic acid is particularly preferred. When the acid (C) is an aromatic monoacid, it is advantageously selected from the group consisting of benzoic acid, naphthoic acid and phenylacetic acid.

[0087] When present, the acid (C) is preferably an aromatic monoacid.

[0088] If present, the acid (C) is a monoacid and is used in an amount such that the number of its carboxylic acid groups is advantageously comprised between 0.010 and 2.0% relative to the total number of hydroxyl groups of the glycolic acid and, if present, of the hydroxyl acid (A). The acid (C) is advantageously used in an amount such that the number of its carboxylic acid groups is advantageously at least 0.010%, preferably at least 0.030%, more preferably at least 0.075%, relative to the total number of hydroxyl groups of the glycolic acid and, if present, of the hydroxyl acid (A); and / or is advantageously at most 2.0%, preferably at most 1.50%, more preferably at most 1.20%, most preferably at most 1.00%, even more preferably at most 0.75%, relative to the total number of hydroxyl groups of the glycolic acid and of the hydroxyl acid (A).

[0089] The branched poly(hydroxy acid) polymer according to this fifth embodiment may optionally comprise repeat units derived from at least one polyacid (O) as defined above. The polyacid (O) may comprise two carboxylic acid groups or more than two carboxylic acid groups, in particular three or four carboxylic acid groups.

[0090] Among suitable polyacids (O) there may be mentioned phthalic acid, tricarballylic acid, butane-1,2,3,4 tetracarboxylic acid, 1,2,4,5-benzenetetracarboxylic acid (pyromellitic acid). The polyacid (O) is preferably an aromatic diacid, more preferably phthalic acid, most preferably isophthalic acid.

[0091] If present, the polyacid (O) is used in an amount such that the number of its carboxylic acid groups is comprised between 0.025 and 1.200% relative to the total number of hydroxyl groups of the glycolic acid and, if present, of the hydroxyl acid (A). If present, the polyacid (O) is used in an amount such that the number of its carboxylic acid groups is advantageously at least 0.025%, preferably at least 0.050%, more preferably at least 0.100% and / or advantageously at most 1.200%, preferably at most 1.000%, more preferably at most 0.900%, most preferably at most 0.750%, especially most preferably at most 0.650% relative to the total number of hydroxyl groups of the glycolic acid and, if present, of the hydroxyl acid (A). It has been found that an amount of polyacid (O) such that the number of its carboxyl groups is comprised between 0.150 and 0.550% relative to the total number of hydroxyl groups of the glycolic acid and, if present, of the hydroxyl acid (A) is particularly useful.

[0092] The branched poly(hydroxy acid) polymers as detailed above may be obtained by a process comprising polycondensing glycolic acid, optionally at least one hydroxy acid (A), at least one polyol (H), at least one alcohol (AO), optionally at least one acid (C) and optionally at least one polyacid (O). In said process, a polycondensation catalyst may optionally be added to the monomer mixture. Such polycondensation catalysts are well known to those skilled in the art and may be selected, for example, from tin(II) chloride, stannous octoate, zinc acetate, zinc lactate, antimony trioxide, benzenesulfonic acid, para-toluenesulfonic acid, methanesulfonic acid, orthophosphoric acid and mixtures thereof. Methanesulfonic acid and mixtures of methanesulfonic acid with other catalysts, those disclosed above or others, are particularly preferred.

[0093] If added, such catalysts are usually added in an amount of about 0.001 to 2 mole %, particularly about 0.002 to 0.1 mole %, based on the total moles of monomers in the monomer mixture.

[0094] Preferably, the polycondensation step is at least partially carried out at a temperature such that the mixture of monomers and the growing polymer formed are in the molten phase. Generally, after the step of polycondensation in the melt, which provides a prepolymer optionally comprising unreacted glycolic acid, hydroxy acid (A) (if present), polyol (H), alcohol (AO), monoacid (C) (if present) and polyacid (O) (if present), the polycondensation is then continued at a temperature such that the prepolymer is in the solid state (this step will be referred to hereinafter as solid state polymerization or SSP).

[0095] Hence, the process generally comprises a first step of polymerization in the melt to form a prepolymer and a second step of solid state polymerization (SSP) to increase the molecular weight of the prepolymer.

[0096] In the first step, a temperature is selected to maintain the monomer mixture and, as the reaction proceeds, the prepolymer that is formed, in a molten state.

[0097] Generally, the first step of polycondensation in the melt is accomplished by maintaining the reaction mixture at a temperature in the range of 160-240° C. with stirring.

[0098] The prepolymer, optionally containing residual monomers, as detailed above, obtained from the first step of polymerization in the molten state, is subjected to a solidification and compaction step so as to provide a particulate prepolymer material in the form of discrete particles.

[0099] The particulate prepolymer can be processed from the molten state in the form of pearls or pellets by standard techniques of pelletizing and / or pastillization, or can be recovered as solidified pieces and milled to provide a powder.

[0100] As detailed above, if the prepolymer, possibly containing residual monomers, is recovered by solidification in the form of small pieces, a milling step is required, which can be carried out by any means known to the skilled artisan, for example by milling in a high speed grinder or in a rotary mill.

[0101] The SSP step may be carried out by exposing the prepolymer, optionally containing residual monomers as detailed above, in its solid state, either under vacuum or under an inert gas atmosphere (e.g. under nitrogen) or both, for one hour or even several days, to a temperature higher than the glass transition temperature of said prepolymer, optionally containing residual monomers as detailed above, but lower than its melting temperature. Typically, such an SSP step may be carried out at a temperature of 140-240°C, in particular 150-230°C, for example at about 170-220°C and at a pressure of less than 5 kPa.

[0102] Depending on the nature of the residual monomers in the prepolymer, their proportion and the target final viscosity / molecular weight, the temperature and pressure during the overall polycondensation step, the duration of the SSP step may be from a few hours to a week, in particular from 6 to 200 h, for example about 10 to 150 h.

[0103] Preferably, the polycondensation reaction in the melt phase is carried out under vacuum in order to evaporate the water of reaction and to prevent it from hydrolyzing the polymer chains that are being formed. Very particularly preferably, the polycondensation reaction in the melt phase is started at atmospheric pressure and reduced pressure is gradually applied until a pressure of the order of a few kPa is reached, in particular less than 5 kPa, preferably less than 2 kPa. The SSP step is typically carried out at a pressure of about 0.01 to 5 kPa, preferably about 0.01 to 2 kPa.

[0104] Chain extender, agent (CE) The chain extender, agent (CE), used in the compositions of the present invention contains epoxy functionality and has a number average functionality of 2 or greater.

[0105] Suitable agents (CE) include oligomeric or polymeric compounds that contain an average of two or more epoxy functional groups per molecule.

[0106] Notable non-limiting examples of suitable agents (CE) are, for example, di- or polyglycidyl esters of di- or polycarboxylic acids or di- or polyglycidyl ethers of di- or polyols, poly(ethylene-co-glycidyl methacrylate) copolymers, poly(ethylene-co-methyl(meth)acrylate-co-glycidyl acrylate) copolymers, poly(ethylene-co-n-butylacrylate-co-glycidyl acrylate) copolymers and copolymers of styrene and glycidyl(meth)acrylate.

[0107] Advantageously, the agent (CE) useful for forming the composition of the invention, as defined above, is a low molecular weight styrene-acrylate copolymer containing epoxy functional groups.

[0108] In particular, the agent (CE) is the polymerization product of (i) at least one epoxy-functional (meth)acrylic monomer; and (ii) at least one styrenic and / or (meth)acrylic monomer, where the polymerization product has a number average functionality of at least 2.

[0109] The agent (CE) may advantageously be selected from among the polymerization products of (i) at least one epoxy-functional (meth)acrylic monomer and (ii) at least one styrenic and / or (meth)acrylic monomer having an epoxy equivalent weight of about 180 to about 2800, a number average epoxy functionality of at least 2 and less than about 30, a weight average epoxy functionality up to about 140, and a number average molecular weight (Mn) of less than 6000. The agent (CE) may have a polydispersity index of 1.5 to 5.0.

[0110] Preferably, the agent (CE) is a copolymer of styrene and glycidyl (meth)acrylate. Notable examples are, for example, Joncryl® ADR4368 and Joncryl® ADR4468 sold by BASF.

[0111] The agent (CE) is present in the composition of the present invention in an amount of from 0.01 to less than 1.00% by weight, based on the combined weight of the polymer (HAP) and the agent (CE).

[0112] The agent (CE) may advantageously be present in an amount ranging from 0.05 to 0.95% by weight, preferably from 0.08 to 0.90% by weight, or even from 0.10 to 0.85% by weight, and more preferably from 0.10 to 0.80% by weight.

[0113] A good balance of properties was obtained using compositions containing 0.10-0.75 wt.% of the agent (CE) based on the combined weight of the polymer (HAP) and the agent (CE).

[0114] Chain extended polymer, polymer (CEHAP) A further object of the present invention is a chain extended polymer [polymer (CEHAP)] comprising a backbone of a branched poly(hydroxy acid) polymer, polymer (HAP), covalently bonded to a chain extender, a unit derived from agent (CE). The amount of units derived from agent (CE) is from 0.01 to less than 1.00% by weight, based on the total weight of polymer (CEHAP). The amount of units derived from agent (CE) is from 0.05 to 0.95% by weight, preferably from 0.08 to 0.90% by weight, even from 0.10 to 0.85% by weight, more preferably from 0.10 to 0.80% by weight, even from 0.10 to 0.75% by weight, based on the total weight of polymer (CEHAP).

[0115] Advantageously, the polymer (CEHAP) comprises a branched poly(hydroxy acid) polymer, a backbone of the polymer (HAP), covalently bonded to units derived from at least one compound selected from the group consisting of di- or polyglycidyl esters of di- or polycarboxylic acids, di- or polyglycidyl ethers of di- or polyols, poly(ethylene-co-glycidyl methacrylate) copolymers, poly(ethylene-co-methyl(meth)acrylate-co-glycidyl acrylate) copolymers, poly(ethylene-co-n-butylacrylate-co-glycidyl acrylate) copolymers, copolymers of styrene and glycidyl(meth)acrylate.

[0116] More advantageously, the polymer (CEHAP) comprises a backbone of a branched poly(hydroxy acid) polymer, the polymer (HAP), covalently bonded to units derived from at least one compound selected from the group consisting of: (i) the polymerization product of at least one epoxy-functional (meth)acrylic monomer; and (ii) at least one styrenic and / or (meth)acrylic monomer, wherein the polymerization product has a number average functionality of at least 2.

[0117] In an advantageous embodiment of the invention, the polymer (CEHAP) comprises a backbone of the polymer (HAP) covalently bonded to units derived from at least one compound selected from the group consisting of: (i) the polymerization product of at least one epoxy-functional (meth)acrylic monomer; and (ii) at least one styrenic and / or (meth)acrylic monomer, wherein the polymerization product has a number average functionality of at least 2. The covalently bonded units are present in an amount of from 0.01 to less than 1.00 wt%, from 0.05 to 0.95 wt%, from 0.08 to 0.90 wt%, from 0.10 to 0.85 wt%, from 0.10 to 0.80 wt%, from 0.10 to 0.75 wt%, based on the total weight of the polymer (CEHAP).

[0118] The polymer (CEHAP) can be obtained by reaction of the polymer (HAP) with the agent (CE). The reaction is preferably carried out in the melt phase of the polymer (HAP), i.e. in the absence of bulk solvent, according to any method known in the art.

[0119] In a first embodiment, a chain-extended polymer (CEHAP) can be prepared from the composition of the invention comprising the polymer (HAP) and the agent (CE). Advantageously, after mixing the polymer (HAP) and the agent (CE), the composition is fed into an extruder or any other suitable device for carrying out a reaction in the melt phase of the polymer.

[0120] Alternatively, the polymer (HAP) and the agent (CE) may be fed separately to the extruder at different times.

[0121] After a length of extrusion sufficient to effect reaction between the epoxy functional groups in the agent (CE) and the polymer (HAP), the polymer (CEHAP) is obtained from the extruder, typically in the form of pellets.

[0122] A suitable extruder may be a co-rotating, twin-screw extruder, which is known to provide high intensity distributive and dispersive mixing.

[0123] In a second embodiment, the agent (CE) could be reacted with the polymer (HAP) during or at the end of the solid state polymerization step (SSP) as detailed above.

[0124] Hence, in this embodiment, the process for preparing the polymer (CEHAP) comprises a first step of polycondensing in the melt (i) at least one hydroxy acid (A), (ii) optionally at least one acid (C), and (iii) at least one multifunctional reactant (F) to form a prepolymer, as detailed above, and a second step of solid state polymerization (SSP) in the presence of an agent (CE) in an amount of 0.01 to less than 1.0 wt. % relative to the total weight of the monomers.

[0125] In a further embodiment, the agent (CE) could be added to the monomer mixture during the first polycondensation step in the melt.

[0126] In such an embodiment, the method thus comprises a first step of polycondensing (i) at least one hydroxy acid (A), (ii) optionally at least one acid (C), (iii) at least one multifunctional reactant (F) and from 0.01 to less than 1.0 wt. % of a reagent (CE) relative to the total weight of monomers in the melt to form a prepolymer, and a second step of solid state polymerization (SSP).

[0127] The resulting polymer (CEHAP) can then be processed in a number of ways, such as being extruded through a die, injection molded or blow molded into a desired shape.

[0128] The composition or chain extended polymer (CEHAP) of the present invention may further comprise fillers and other additives known in the art.

[0129] The nature of the filler is not particularly limited, and any filler in fiber or whisker form can be used. Fillers other than fiber or whisker-like fillers can also be used, such as sheet-like (layered), powder-like, or granular fillers. Furthermore, fillers of various compositions can be used, such as carbon-based, metal-based, or silicon-based fillers.

[0130] The chain extended polymers (CEHAP) of the present invention may be fabricated into articles using known melt processing techniques such as injection molding, extrusion or any other molding or thermoforming technique.

[0131] A further object of the invention is therefore an article made of the polymer (CEHAP). Notable non-limiting examples of suitable articles are, for example, bottles, articles for hydrocarbon resource recovery, packaging films, sanitary products, disposable pods, structural parts for electronic applications or biomedical articles.

[0132] The polymer (CEHAP) has particularly advantageous decomposition behavior that makes it particularly useful in the manufacture of articles for hydrocarbon resource recovery that decompose favorably into the ground even at low temperatures. The article is preferably a downhole tool, a downhole tool component or an element of a downhole tool component.

[0133] "Downhole tool" means, according to the present invention, a tool used in a wellbore or borehole provided during drilling of an oil well from land (including above water) towards a producing reservoir to obtain hydrocarbon resources such as oil, g. shale oil and natural gas such as shale gas, and that serves as a flow path for the hydrocarbon resources to be recovered after the completion of the well. Downhole tool or downhole tool member or element of downhole tool member advantageously refers to a piece of oilfield equipment used during drilling, downhole completion or workover, including the tools used to plug and fracture the borehole.

[0134] The downhole tool or downhole tool member or element of a downhole tool member is preferably selected from the group consisting of frac plugs or disassemblable plugs, bridge plugs, cement retainers, perforating gums, ball sealers, frac balls, diverting balls, ball seats, mandrels, slips, wedges, rings, sealing plugs, frac sleeves, fracturing sleeve pistons (also known as "pistons" or "piston plugs") and packers.

[0135] The downhole tools or downhole tool components or elements of downhole tool components of the present invention may be manufactured using known melt processing techniques, such as injection molding, cast molding, extrusion, or any other molding or thermoforming technique. Additional manufacturing processes may be applied to modify the shape of the downhole tool after melt processing, such as cutting or drilling. Furthermore, the downhole tool may include a combination of moldings using any number of the aforementioned melt processing techniques and subsequent manufacturing processes as required.

[0136] To the extent that the disclosures of any patents, patent applications, and publications incorporated herein by reference conflict with the statements of this application to the extent that a term may be unclear, the statements of this application shall control.

[0137] The present invention will now be described in more detail with reference to the following examples, the purposes of which are merely illustrative and are not intended to limit the scope of the invention.

[0138] To the extent that the disclosures of any patents, patent applications, and publications incorporated herein by reference conflict with the statements of this application to the extent that a term may be unclear, the statements of this application shall control. EXAMPLES

[0139] Example 1 A 7.5 L stainless steel double jacketed reactor equipped with a heater, condenser, temperature and pressure sensors, and mechanical stirrer was charged with 4500 g (41.420 moles, based on 1.0000 moles) of 70 wt % aqueous glycolic acid solution, 10.004 g (0.075 moles, 0.0018 moles per mole of glycolic acid), 3.584 g (0.025 moles, 0.0006 moles per mole of glycolic acid), and 0.536 g (0.006 moles, 0.00014 moles per mole of glycolic acid) of methanesulfonic acid.

[0140] The reactor was then closed and purged three times using alternating vacuum and nitrogen. The reaction solution was rapidly heated to 50° C. under mechanical stirring. The pressure was reduced to 60 kPa and heating was continued from 50° C. to 100° C. over 30 minutes. Water distillation was started. The temperature was slowly increased to 130° C. over 60 minutes to allow water distillation to continue gently. When most of the water had been removed, the temperature was increased more quickly to 220° C. over 30 minutes.

[0141] Once 220° C. was reached, the pressure was gradually reduced to 3 kPa over 30 min. The temperature was then finally increased to 230° C. and held steady for the remainder of the synthesis. Vacuum was applied for an additional 270 min to increase the glycolic acid conversion.

[0142] The reaction mixture was then returned to atmospheric pressure using nitrogen. The polymer was removed from the kettle through the bottom valve and collected in a stainless steel (SS) tray on dry ice. The hard solidified polymer mass was removed and weighed. The crude yield was: 2.10 kg (about 88%).

[0143] The polymer was ground into small particles less than 2 mm in diameter using a high speed grinder, sieved through a 2 mm sieve, and further dried in a vacuum oven at 90° C. overnight.

[0144] The powder was pelletized in a BRABENDER extruder, 19 mm diameter, equipped with a 25 L / D monoscrew with a compression ratio of 3:1 to obtain uniform particle size distribution and consistency. The die was a one-strand die (2 mm hole) and the strands were "die face cut" in dry conditions. The screw speed used was 60 rpm and the temperature profile was kept low (flat temperature profile of 195° C., 4 heating zones in the extruder; 1 heating zone in the die) to counter the low viscosity of the molten polymerized prepolymer. Typical throughput was about 2.1 kg / h. The resulting pellet size was approximately 2 mm in diameter and approximately 3 mm in length.

[0145] The pellets so obtained were introduced into a double-walled rotary tumbler unit for uniform mixing and further polymerized in solid phase by heating and vacuuming. The tumbler used had a total volume of 15 L / effective volume of 6 L. Approximately 2 kg of polymer was used per batch.

[0146] After closing the tumbler, rotation was started at 8 rpm. The vacuum pump was started to achieve a 0.5-1 kPa vacuum in the tumbler. At the same time, the tumbler was flushed with nitrogen (flow rate set at 50 L / h). The oil circulating in the double wall was heated in order to increase the temperature from room temperature to 214 °C in 16 h.

[0147] The tumbler was equipped with a sampling valve so that samples of the reduced amount of polymer could be carefully removed and the melt viscosity analyzed using a parallel plate rheometer at various points during the solid state polymerization (SSP).After achieving the desired melt viscosity, the heat was turned off, the SSP was stopped, and the product was cooled.

[0148] After 66 hours of SSP at 214°C, 10 seconds -1 This resulted in 1.8 kg of a branched poly(glycolic acid) polymer, polymer HAP-1, having a melt viscosity of 647 Pa×sec at a shear rate of 1000 rpm.

[0149] Residual methanesulfonic acid in the final polymer after SSP was titrated according to the described method and found to be 0.005 mol % with respect to glycolic acid units.

[0150] Example 2 The polymer of Example 1 (HAP-1; 9.053 kg) and Joncryl® ADR 4468 (CE-1; 0.01814 kg, 0.2 wt%) were added to a plastic container, sealed, and mixed by vigorously shaking at room temperature for 3 minutes to produce a preblend. The preblend was then dried at 80° C. in a drying oven (dew point −40° C.) for 15 h. The preblend was fed by a nitrogen blanketed weight loss feeder into a twin-screw co-rotating, partially intermeshing extruder with 26 mm Coperion® ZSK-26, 12 barrel sections, and an overall L / D ratio of 48. Barrel sections 2-12 were heated to set point temperatures as follows: 2-9 240-250° C., 10-12 220° C., die temperature 250° C. The extruder screw speed was operated at 200 rpm with a throughput of 11 kg / h and 3.3 kPa applied vacuum. The resulting strand was quenched with water and pelletized to obtain 8.392 kg of CEHAP-1. The pellets of CEHAP-1 were dried at 70°C for 1.5 h and then at 90-110°C until the moisture level was less than 100 ppm as measured by coulometric Karl Fischer titration. The dried pellets of CEHAP-1 were then molded into test specimens (ASTM D638 Type I tensile bars and ASTM D790 flexural bars) using an injection molding machine operating at an injection temperature of 260°C and a mold temperature of 130°C. The samples were then annealed in an oven at 150°C under nitrogen atmosphere for 1 h, followed by heat treatment at 80°C under nitrogen atmosphere for 4 h.

[0151] Example 3 The procedure of Example 2 was followed, but using a preblend prepared from 9.026 kg of polymer HAP-1 and 0.04536 kg (0.5 wt%) of CE-1. Polymer CEHAP-2 was obtained.

[0152] Comparative Example 1 The procedure of Example 2 was followed, except that a preblend made with only HAP-1 was used.

[0153] Comparative Example 2 The procedure of Example 2 was followed, but using a preblend prepared from 8.9811 kg of HAP-1 and 0.0907 kg (1.0 wt%) of CE-1. This composition caused fluctuations in extruder pressure, resulting in irregular flow through the die and non-melt. Therefore, proper pellets could not be formed and specimens were not molded for testing.

[0154] Mechanical property measurements Tensile properties were measured according to the procedures set forth in ASTM D638, and flexural properties were measured according to the procedures set forth in ASTM D790. Tensile tests were performed at a test speed of 50.8 mm / min. Data are reported as the mean ± standard deviation of five to six specimens. Properties are summarized in Table 1.

[0155] [Table 1]

[0156] Polymers CEHAP-1 and CEHAP-2, with 0.2 and 0.5 wt % units derived from CE-1, respectively, exhibit increased ductility (measured in terms of elongation at break) while retaining the high modulus of the branched polymer HAP-1.

[0157] The polymer of Comparative Example 2, containing 1.0 wt. % units derived from Agent CE-1, could not be molded into a finished part suitable for testing.

[0158] Example 4 Evaluation of decomposition behavior Injection molded ASTM D790 flex bar PGA was cut to 5 g. A 500 mL Erlenmeyer flask was charged with 5 g of flex bar PGA sample, a magnetic stir bar, and DI water (250 ml). The flask was set to stir at 60 rpm and the water was heated to 65° C. During the experiment, the temperature and water level were monitored and adjusted as necessary to maintain constant conditions. After 7 days of stirring at 65° C., the water mixture was filtered through a Buchner funnel (2 mm pore size) and the remaining PGA portion was dried in a vacuum oven at 30° C. to constant weight. The remaining weight is reported as a percentage of the original weight of the flex bar. The experiment was performed in triplicate and the average remaining weight is reported in Table 2.

[0159] [Table 2]

[0160] Polymers CEHAP-1 and CEHAP-2, having 0.2 and 0.5 wt. % units derived from CE-1, respectively, exhibit increased ductility and high modulus while exhibiting high degradability, making them particularly useful for the manufacture of articles for hydrocarbon resource recovery, such as downhole tools, that also degrade favorably into the ground.

Claims

1. A composition comprising: (i) at least one hydroxy acid [hydroxy acid (A)] having only one hydroxyl group and only one carboxylic acid group; (ii) optionally, at least one carboxylic acid [acid (C)] having one or two carboxylic acid groups and no hydroxyl group; (iii) - a compound containing at least one epoxy functional group, preferably a compound selected from the group consisting of epoxy silanes and polyepoxides; and - a mixture containing at least one polyol [polyol (H)] containing at least three hydroxyl groups and no carboxylic acid group, and at least one polyacid [polyacid (O)] containing at least two carboxylic acid groups and no hydroxyl group; and - a mixture containing at least one polyol [polyol (H)] containing at least three hydroxyl groups and no carboxylic acid group, and at least one alcohol [alcohol (AO)] containing one or two hydroxyl groups and no carboxylic acid group and at least one polyfunctional reactant [reactant (F)] different from hydroxy acid (A) and acid (C), selected from the group consisting of A branched poly(hydroxy acid) polymer [polymer (HAP)] obtained from the polycondensation reaction of a monomer mixture containing A chain extender [reagent (CE)] containing an epoxy functional group and having a number average functionality of 2 or more in an amount of 0.01 to less than 1.00% by weight based on the total weight of polymer (HAP) and reagent (CE). A composition containing

2. The composition according to claim 1, wherein the polymer (HAP) is obtained from the polycondensation reaction of a monomer mixture containing at least one hydroxy acid (A) which is glycolic acid, and a reactant (F) which is a mixture containing at least one polyol (H) containing at least three hydroxyl groups and at least one polyacid (O) containing at least three carboxylic acid groups.

3. The polymer (HAP) is obtained from the polycondensation reaction of a monomer mixture containing at least one hydroxy acid (A) which is glycolic acid; optionally at least one acid (C); and at least one reactant (F) selected from a mixture containing at least one polyol (H) containing at least three hydroxyl groups and at least one polyacid (O) containing at least three carboxylic acid groups, and, when present, the amount of acid (C) is such that the number of its carboxylic acid groups is included in the range of 0.0001 to 0.010% with respect to the number of hydroxyl groups of the hydroxy acid (A). The composition according to claim 1 or 2.

4. The polymer (HAP) is obtained from the polycondensation reaction of a monomer mixture containing glycolic acid; optionally at least one hydroxy acid (A) in an amount of at most 5 mol% with respect to the total moles of glycolic acid and the hydroxy acid (A) different from glycolic acid; optionally at least one carboxylic acid (C) having one carboxylic acid group; and at least one reactant (F) selected from a mixture containing at least one polyol (H) containing at least three hydroxyl groups and at least one polyacid (O) selected from an aromatic acid containing two aromatic carboxylic acid groups, and: the amount of polyol (H) is such that the number of its hydroxyl groups is included in the range of 0.050 to 1.200% with respect to the total number of carboxyl groups of glycolic acid and, when present, the hydroxy acid (A); the amount of polyacid (O) is such that the number of its carboxylic acid groups is included in the range of 0.050 to 0.750% with respect to the total number of hydroxyl groups of glycolic acid and, when present, the hydroxy acid (A); and, when present, the amount of acid (C) is such that the number of its carboxylic acid groups is included in the range of 0.0001 to 0.010% with respect to the total number of hydroxyl groups of glycolic acid and, when present, the hydroxy acid (A). The composition according to claim 1.

5. The polymer (HAP) is obtained from a polycondensation reaction of glycolic acid with; optionally, at least one hydroxy acid (A) different from glycolic acid (wherein the molar amount of hydroxy acid (A) is at most 5 mol% based on the total moles of glycolic acid and hydroxy acid (A)), if any; optionally, at least one carboxylic acid (C); optionally, at least one polyacid (O); and at least one reactant (F) selected from a mixture containing at least one polyol (H) and at least one alcohol (AO), and the amount of polyacid (O) is such that the number of its carboxylic acid groups is included in the range of 0.025 to 1.200% based on the total number of hydroxyl groups of glycolic acid and, if present, said hydroxy acid (A). The composition according to claim 1.

6. The reagent (CE) is selected from the group consisting of di- or polyglycidyl esters of di- or polycarboxylic acids, di- or polyglycidyl ethers of di- or polyols, poly(ethylene-co-glycidyl methacrylate) copolymers, poly(ethylene-co-methyl(meth)acrylate-co-glycidyl acrylate) copolymers, poly(ethylene-co-n-butyl acrylate-co-glycidyl acrylate) copolymers, and copolymers of styrene and glycidyl (meth)acrylate. The composition according to claim 1 or 2.

7. The reagent (CE) is selected from the group consisting of polymerization products of (i) at least one epoxy-functional (meth)acrylic monomer and (ii) at least one styrenic and / or (meth)acrylic monomer. The composition according to claim 1 or 2.

8. The composition according to claim 1 or 2, comprising 0.05 to 0.95% by weight of the reagent (CE) based on the total weight of the polymer (HAP) and the reagent (CE).

9. A chain-extended polymer [polymer (CEHAP)] comprising a backbone containing a polymer (HAP) covalently bonded to units derived from the reagent (CE) as defined in claim 1 or 2, wherein the amount of units derived from the reagent (CE) is less than 0.01 to 1.00% by weight based on the weight of the polymer (CEHAP).

10. A method for preparing a polymer (CEHAP) comprising reacting a molten polymer (HAP) with a reagent (CE) in an amount of from 0.01 to less than 1.00% by weight based on the total weight of the polymer (HAP) and the reagent (CE).

11. The method according to claim 10, which is carried out in an extruder and comprises either feeding the composition according to claim 1 or 2 into the extruder or feeding the polymer (HAP) and the reagent (CE) separately into the extruder.

12. A method for preparing a polymer (CEHAP) comprising a first step of polycondensing (i) at least one hydroxy acid (A), (ii) optionally at least one acid (C), and (iii) at least one polyfunctional reactant (F) in a molten state to form a prepolymer, and a second step of solid state polymerization (SSP), as defined in claim 1, wherein the reagent (CE) is added in an amount of from 0.01 to less than 1.0% by weight based on the total weight of the polymer (HAP) and the reagent (CE) either during the first polycondensation step or during the second solid state polymerization step.

13. A chain-extended polymer [polymer (CEHAP)] comprising a backbone containing a polymer (HAP) covalently bonded to units derived from a reagent (CE), as defined in claim 1 or as defined in claim 1, wherein the amount of units derived from the reagent (CE) is from 0.01 to less than 1.00% by weight based on the weight of the polymer (CEHAP), and an article comprising the polymer (CEHAP).

14. An article according to claim 13, which is a bottle, an article for hydrocarbon resource recovery, preferably a downhole tool or a downhole tool member, a packaging film, a sanitary product, a disposable pod, a structural component for electronic applications or a biomedical article. **Claim 15** A method for manufacturing an article comprising a chain-extended polymer [polymer (CEHAP)] comprising a backbone comprising a polymer (HAP) covalently bonded to a unit derived from a reagent (CE) as defined in claim 1 or in the composition according to claim 1, wherein the amount of the unit derived from the reagent (CE) is less than 0.01 to 1.00% by weight based on the weight of the polymer (CEHAP), said method comprising melt processing and injection molding or extrusion of a polymer (CEHAP) comprising a backbone comprising a polymer (HAP) covalently bonded to a unit derived from a reagent (CE) as defined in claim 1 or in the composition according to claim 1, wherein the amount of the unit derived from the reagent (CE) is less than 0.01 to 1.00% by weight based on the weight of the polymer (CEHAP).