Method for preparing a 1,4:3,6-dianhydrohexitol diester composition

Abstract

The invention relates to a method for preparing a C13-C29 alkyl diester of 1,4:3,6-dianhydrohexitol, said method comprising: a) a first step of esterification of 1,4:3,6-dianhydrohexitol with a fatty acid having a C13-C29 alkyl chain, said fatty acid being in excess, so as to form a reaction crude comprising a C13-C29 alkyl diester of 1,4:3,6-dianhydrohexitol and unreacted fatty acid; b) a second step of esterification of the unreacted fatty acid with a primary or aromatic diol.

Description

METHOD FOR PREPARING A DIEYSTER COMPOSITION OF 1, 4:3,6- DIANYDROHEXITOL technical field

[0001] The invention relates to a process for preparing a 1,4:3,6-dianydrohexitol alkyl diester composition and their use in the preparation of polycarbonate, in particular to improve the flowability of polycarbonate in the molten state. State of the art

[0002] It is known that 1,4:3,6-dianydrohexitol alkyl diesters such as isosorbide can be added to a polymer to facilitate its shaping. They then act as a "plasticizer".

[0003] The plasticizers most commonly used today belong to the phthalate ester family. Phthalates are readily available on the market at low cost; however, efforts are underway to replace them due to toxicity concerns.

[0004] As an example, patent EP 3 443 033 B1 describes how C8 / C10 alkyl isosorbide diesters, marketed by the Applicant under the trade name Polysorb ID46, make it easier to prepare polycarbonates, in particular by improving their flow in the molten state.

[0005] Alkyl diesters of 1,4:3,6-dianydrohexitol are classically prepared by esterification of 1,4:3,6-dianydrohexitol with an excess fatty acid, typically in the presence of an acid catalyst. The crude reaction mixture includes unreacted fatty acid (residual fatty acid). Since this fatty acid negatively affects the use of the diester compositions as a plasticizer, it is removed after the esterification step by subjecting the crude reaction mixture to either a distillation step or a liquid-liquid washing step involving washing with water in the presence of a weak base such as sodium bicarbonate, followed by a drying step.

[0006] As detailed in application WO 2006 / 103338 A1, certain compositions of 1,4:3,6-dianydrohexitol diester exhibit an undesirable yellow coloration, particularly when these compositions are intended for use in the production of transparent plastics such as polycarbonate. The solution proposed in this patent document is to treat the crude reaction mixture with a specific acid, hypophosphorous acid, which acts as a decolorizing agent.

[0007] There is a continuous need to develop new additives for the preparation of synthetic polymers.

[0008] In the course of its research, the Applicant Company observed that in polycarbonate manufacturing processes, C8 / C10 alkyl diesters did not produce the desired effect and, moreover, imparted discoloration to the polycarbonate. It therefore developed new long-chain alkyl diesters of 1,4:3,6-dianhydrohexitol. During development, it found that applying a step to remove residual fatty acids by distillation or liquid-liquid washing resulted in the degradation of a fraction of the diester to a monoester and yellowing of the product.

[0009] There is therefore a need to find a process that makes it possible to prepare on an industrial scale, with good yields, a composition of a long-chain alkyl diester of 1,4:3,6-1,4:3,6-dianhydrohexitol with low colouring and minimal residual fatty acid content, which is usable in the preparation of polycarbonate, in particular during its shaping. Description First aspect

[0010] According to a first aspect, the present invention relates to a process for preparing a composition of a C13-C29 alkyl diester of 1,4:3,6-dianydrohexitol, said process comprising: a) a first step of esterification of 1,4:3,6-dianydrohexitol with a fatty acid having a C13-C29 alkyl chain, said fatty acid being in excess, so as to form a crude reaction comprising a C13-C29 alkyl diester of 1,4:3,6-dianydrohexitol and unreacted fatty acid; b) a second step of esterification of the unreacted fatty acid with a primary or aromatic diol.

[0011] As previously stated, the Applicant has observed that when a composition obtained by esterification of 1,4:3,6-dianydrohexitol with a long-chain fatty acid is purified by distillation, the resulting composition exhibits undesirable coloration. Regarding liquid-liquid washing, the Applicant has observed that the drying step, which is applied after washing with water in the presence of a weak base, generates coloration. It has also observed that in the case of saturated fatty acids, the crude reaction product obtained is solid and can only be washed at temperatures above its melting point, typically above 80°C, which results in partial hydrolysis of the 1,4:3,6-dianydrohexitol diester.

[0012] Without wishing to be bound by any particular theory, the inventors believe that in prior art processes, the risk of cleavage of the diester into monoester increases with the temperature applied during removal by distillation or liquid-liquid washing, which is higher the longer the alkyl chain.

[0013] The inventors have developed a process in which, unlike prior art processes, the removal of residual fatty acid does not require distillation or liquid-liquid washing.

[0014] The process according to the invention is simple to implement on an industrial and economical scale. It is based on two esterification steps carried out sequentially.

[0015] The first step involves the esterification of 1,4:3,6-dianydrohexitol by a long chain fatty acid, said fatty acid being in excess, so as to obtain the maximum amount of diester.

[0016] The second step involves esterification of the residual fatty acid by a primary or aromatic diol so as to eliminate most, almost all, or even all of the fatty acid that did not react during the first esterification step.

[0017] This esterification removal has the advantage of being simpler to implement than a distillation removal and of being able to be implemented directly in the esterification reactor than the one used in the first esterification step.

[0018] The process according to the invention is therefore advantageously a single-stage process, that is to say, a preparation process whose steps are carried out successively in the same reactor. The process according to the invention advantageously does not include any isolation, separation, or purification steps by evaporation, for example by distillation.

[0019] Furthermore, as will be detailed below, the compositions obtained according to the process according to the invention exhibit weak colorations and are effective in polycarbonate preparation processes.

[0020] A "C13-C29 alkyl diester" refers to an alkyl diester of 1,4:3,6-dianydrohexitol in which alkyl groups are bonded to the hydroxyl groups of 1,4:3,6-dianydrohexitol. This C13-C29 alkyl diester is produced by the esterification reaction of 1,4:3,6-dianhydrohexitol with a fatty acid. An esterification reaction can be written as follows: R-OH + HO(O)C - R' => RO(O)C-R' + H2O. Thus, if the fatty acid used for esterification has a C13 alkyl chain R', the alkyl group of the ester is R' and is therefore a C13 alkyl group. In the case where only one of the two alcohol functions When the diol reacts by esterification, the ester is a monoester. It is a diester when both alcohol groups of the diol have reacted in an esterification reaction. The C13-C29 alkyl diester of 1,4:3,6-dianhydrohexitol can contain different alkyl groups when the diester is obtained with two different fatty acids.

[0021] For the purposes of this invention, the term "fatty acid having a C13-C29 alkyl chain" refers to an R'-COOH fatty acid comprising 14 to 30 carbon atoms, one carbon atom belonging to the carboxylic acid group (-COOH), the remaining carbon atoms belonging to a substituted or unsubstituted linear or branched alkyl chain comprising between 13 and 29 carbon atoms, or a mixture thereof. The alkyl chain is preferably saturated. The alkyl chain may be substituted by at least one group comprising a heteroatom selected from oxygen and nitrogen, preferably by a ketone or hydroxyl group, or alternatively by an amine group.The chain can be substituted at the end of the alkyl chain by a cyclic group typically containing 5 to 12 carbon atoms, preferably 6 to 10 carbon atoms, preferably by a cyclohexane or cyclopentane ring, or by a C2-C4 alkyl chain linked to the fatty acid alkyl chain at two attachment points so as to form an intrachain ring, preferably an intrachain cyclopropane. Step a)

[0022] In the first step, a 1,4:3,6-dianydrohexitol is esterified by a fatty acid having an alkyl chain at C13-C29. 1,4:3,6-dianhydrohexitol

[0023] 1,4:3,6-dianhydrohexitol is a diol with the molecular formula C6H1O4.

[0024] According to the invention, three isomers of 1,4:3,6-dianhydrohexitol are used: isosorbide, isomannide and isoidide, or a mixture thereof.

[0025] Isosorbide is preferred. Fatty acids

[0026] The fatty acid preferably has an alkyl chain at C13-C29, preferably at C13-C17.

[0027] As an example, the fatty acid can be chosen from stearic acid (octadecanoic acid C18:0), myristic acid (tetradecanoic acid C14:0), palmitic acid (hexadecanoic acid C16:0), isopalmitic acid (14-methylpentadecanoic acid), margaric acid (heptadecanoic acid C17:0), tuberculostearic acid (10-methylstearic acid), lactobacillic acid (10-[(1R,2S)-2-hexylcyclopropyl]decanoic acid), arachidic acid (icosanoic acid C20:0), acid phytanic acid (3,7,11,15-tetramethylhexadecanoic acid), 11-cyclohexylundecanoic acid (11-cyclohexylundecanoic acid) or a mixture thereof.

[0028] The fatty acid is advantageously a C16 or C18 fatty acid, or a mixture thereof.

[0029] Stearic acid and myristic acid are preferred. Excess fatty acids

[0030] In the first step, the fatty acid with a C13-C29 alkyl chain is in excess relative to 1,4:3,6-dianydrohexitol in order to promote the formation of the C13-C29 alkyl diester of 1,4:3,6-dianydrohexitol and to minimize the formation of the corresponding monoester.

[0031] By "excess," we mean a stoichiometric excess, that is, an amount of fatty acid having a C13-C29 alkyl chain greater than the stoichiometric amount required for the esterification reaction with all the hydroxyl groups of the 1,4:3,6-dianydrohexitol present. In other words, in the first step of the process according to the invention, 2y + z moles of fatty acid are preferably reacted with y moles of 1,4:3,6-dianydrohexitol, where y and z are in moles, 2y representing the stoichiometric amount of fatty acid relative to y moles of 1,4:3,6-dianydrohexitol, and z representing the amount of fatty acid that is in excess of said stoichiometric amount. The stoichiometric excess of the fatty acid relative to 1,4:3,6-dianydrohexitol can also be expressed as a percentage using the formula (z / 2y+z)x100.

[0032] The fatty acid is preferably in stoichiometric excess of 10% to 100% relative to 1,4:3,6-dianhydrohexitol. Preferably, 2.2 to 4 moles of fatty acid are reacted per mole of 1,4:3,6-dianhydrohexitol.

[0033] In other words, 1,4:3,6-dianydrohexitol is preferably reacted with the fatty acid at a molar ratio of 1,4:3,6-dianydrohexitol / fatty acid between 1 / 2.2 and 1 / 4. Raw reaction

[0034] For the purposes of the invention, "crude reaction" means the product of the first esterification step of 1,4:3,6-dianydrohexitol with a fatty acid having an alkyl chain at C13-C29, and to which preferably no step of removal of residual fatty acids has been applied, in particular no step of isolation, separation or purification, in particular no step of removal of unreacted fatty acids by distillation or by liquid-liquid method.

[0035] The crude reaction mixture preferably comprises an alkyl diester of 1,4:3,6-dianydrohexitol, an alkyl monoester of 1,4:3,6-dianydrohexitol and unreacted fatty acid. Step b)

[0036] In the second step, the fatty acid that did not react in the first step is esterified with a primary or aromatic diol, in order to remove as much of this fatty acid as possible from the crude reaction product.

[0037] The primary or aromatic diol exhibits greater reactivity than the 1,4:3,6-dianydrohexitol of step a). Preferably, it does not transesterify with the C13-C29 alkyl diester of the 1,4:3,6-dianydrohexitol of the crude reaction product obtained at the end of step a). Primary or aromatic diol

[0038] By "diol" we mean a compound comprising two hydroxyl groups (-OH). The compound is preferably a hydrocarbon structure comprising typically between 2 and 20 carbon atoms, preferably between 2 and 12 carbon atoms.

[0039] The diol used in step b) is a primary or aromatic diol.

[0040] By "primary diol" we mean a diol whose hydroxyl groups are carried by a carbon atom that also carries at least 2 hydrogen atoms.

[0041] By "aromatic diol" we mean a diol whose hydroxyl groups are attached to a carbon atom of an aromatic ring.

[0042] An "aromatic ring" is understood to be a polyunsaturated cyclic hydrocarbon structure in which the cyclic structure is planar and has (4n + 2) delocalized electrons, where n is an integer, having one or more rings condensed together and typically containing 5 to 12 carbon atoms, preferably 6 to 10 carbon atoms. A preferred aromatic ring is phenyl.

[0043] The primary diol preferably comprises 2 to 20 carbon atoms, preferably 2 to 15 carbon atoms.

[0044] As an example, the primary or aromatic diol may be chosen from ethylene glycol, cyclohexanedimethanol (CHDM), neopentyl glycol (NPG), 1,4-butanediol, 1,2-benzenedimethanol, 1,3-benzenedimethanol, 1,4-benzenedimethanol, resorcinol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decandiol, 1,12-dodecanediol or mixtures thereof.

[0045] Ethylene glycol is preferred.

[0046] In the second step, the primary or aromatic diol is preferably introduced in stoichiometric proportions or in slight deficiency relative to the unreacted fatty acid in the first step, in order to eliminate almost all of this fatty acid. Without wishing to be bound by any particular theory, the inventors consider that if the primary or aromatic diol is added in stoichiometric excess relative to the residual fatty acid, the final composition presents a risk of containing monoester of this primary or aromatic diol, which leads to a risk of transesterification and therefore the generation of 1,4:3,6-dianydrohexitol monoester.

[0047] By "primary or aromatic diol in slight deficiency with respect to the fatty acid which did not react in the first step", we mean a stoichiometric deficiency, that is to say a quantity of primary or aromatic diol slightly less than the stoichiometric quantity required for the esterification reaction of all the hydroxyl groups of the fatty acid which did not react in the first step.

[0048] In the first esterification step, between 0.45 and 0.5 moles of primary or aromatic diol are generally reacted per mole of excess fatty acid. Typically, when the first esterification reaction in step a) is carried out with a mole of fatty acid that is in excess of the stoichiometric amount (which can be denoted "z", as detailed above), the second esterification reaction in step b) is carried out with a mole of primary diol that is between 45% and 50% of the mole of fatty acid used in excess of the stoichiometric amount in step a). As an example, when in step a) 2.3 moles of fatty acid are introduced per mole of 1,4:3,6-dianydrohexitol (i.e. an excess of z=0.3 moles of fatty acid) then in step b) it is preferable to react between 0.3x45%=0.135 and 0.3x50% (i.e. 0.3 / 2) =0.15 moles of primary or aromatic diol. Esterification conditions

[0049] The esterification steps can be carried out under the standard implementation conditions already described in the literature. These esterification methods are described, for example, in documents WO 99 / 45060 A1 or WO 2006 / 103338 A1.

[0050] The esterification steps are preferably carried out in the presence of at least one acid catalyst.

[0051] The acid catalyst used can be of a very diverse nature; for example, it can be an acid catalyst chosen from hypophosphorous acid, hydrochloric acid, sulfuric acid, para-toluenesulfonic acid (PTSA), methanesulfonic acid (MSA), trifluoromethanesulfonic acid, trifluoroacetic acid, trichloroacetic acid, ethyl- 2-tin hexanoate, phosphotungstic acid and silicotungstic acid or a mixture of these acids or a macroporous or non-macroporous resin comprising at least one of these acids.

[0052] In the case of mixtures of acid catalysts, they may be introduced into the reaction medium simultaneously, or not.

[0053] The mass amount of acid catalyst can range from 0.05 to 20% relative to the mass of 1,4:3,6-dianhydrohexitol introduced into the reactor, for example from 0.1 to 10%.

[0054] It should be noted that hypophosphorous acid can also act as a color reducer. It can be introduced into the reaction medium simultaneously or separately from another acid catalyst and / or the fatty acid. In one variation, this introduction occurs before or at the beginning of the esterification reaction, i.e., before the introduction of the acid catalyst and / or the fatty acid. Advantageously, and regardless of when it is introduced, the hypophosphorous acid is introduced in an amount between 0.05% and 2%, preferably between 0.1% and 1%, expressed as a dry weight relative to the dry weight of 1,4:3,6-dianydrohexitol(s) used. In another variation, the hypophosphorous acid is introduced, simultaneously or separately from the acid esterification catalyst, in a hypophosphorous acid / acid catalyst ratio of less than 1:1, this ratio being expressed as the dry weight of hypophosphorous acid relative to the dry weight of the acid catalyst.The said ratio may in particular be between 0.01 / 1 and 0.9 / 1, preferably between 0.02 / 1 and 0.8 / 1. When the catalyst is APTS, methanesulfonic acid or phosphotungstic acid, the said ratio may advantageously be between 0.05 / 1 and 0.4 / 1.

[0055] The temperature in the reactor can range from 90 to 200°C, but is generally from 100 to 160°C. To carry out the esterification reaction, water is usually removed to promote the formation of the diester; this removal can be achieved, for example, by distilling the reaction mixture. To facilitate this removal, the reaction mixture can be placed under vacuum, for example, at a level ranging from 10 to 200 mbar. Reaction conditions such as vacuum level and temperature can be varied during the reaction.

[0056] The first esterification step typically lasts until satisfactory conversion to 1,4:3,6-dianhydrohexitol diester is achieved. It can vary widely, ranging from 1 to 10 hours.

[0057] The second esterification stage generally lasts until a satisfactory level of free fatty acid is removed. It can vary widely, ranging from 1 to 10 hours.

[0058] A neutralization step of the introduced catalyst can also be carried out by introducing a base, for example sodium hydroxide, in molar quantities equivalent to the molar quantities of catalyst introduced. This neutralization step is preferably carried out after the second esterification step. Colour reducer

[0059] The process according to the invention may also include a step of decolorizing the reaction crude from step a) using color reducing agents, for example activated carbon or hydrogen peroxide, or bleaching earths such as bleaching clay, bentonite or montmorillonite.

[0060] This step can be carried out successively in one of steps a) and / or b). In this embodiment, the bleaching agents are added at the end of one of steps a) and / or b).

[0061] This step can also be carried out simultaneously with steps a) and / or b). In this embodiment, the bleaching agents are added at the beginning of one or both of steps a) and / or b).

[0062] Activated carbon treatment is carried out, for example, by contacting the crude reaction product with 1 to 5% by weight of activated carbon. The temperature during this treatment can be close to 100°C. The duration is generally several tens of minutes, for example, about an hour. At the end of the treatment, the activated carbon is separated by filtration. For treatment with bleaching earths, the process is similar to that with activated carbon.

[0063] A typical hydrogen peroxide bleaching treatment involves adding 0.5% to 2% of 100% hydrogen peroxide to the fabric to be bleached over a period of 30 to 60 minutes, at a temperature between 90°C and 100°C. The mixture is then agitated at this temperature for one to two hours. When combining these two bleaching methods, the hydrogen peroxide treatment is preferably applied before the activated charcoal treatment. Favorite mode

[0064] In a preferred embodiment, the process according to the invention allows the preparation of a composition of a C13-C29 alkyl diester of isosorbide, said process comprising: a) a first step of esterification of isosorbide by a fatty acid having an excess of a C13-C29 alkyl chain, for example in an isosorbide / fatty acid molar ratio of between 1 / 2.3 and 1 / 3 so as to form a crude reaction comprising an alkyl diester of isosorbide and the unreacted fatty acid; b) a second step of esterification of the unreacted fatty acid by a primary or aromatic diol, preferably by ethylene glycol, in which the fatty acid having a C13-C29 alkyl chain is preferably a fatty acid having an alkyl chain of C13, C14, C15, C16, C17 or C18. Second aspect

[0065] A second object of the invention relates to a C13-C29 alkyl diester composition of 1,4:3,6-dianydrohexitol capable of being obtained by the process of the first object of the invention.

[0066] Indeed, when the diester composition is obtained from different 1,4:3,6-dianydrohexitols, different primary and / or aromatic diols, and / or different fatty acids having a C13-C29 alkyl chain, very complex and diverse compositions are obtained which can only be defined more satisfactorily by the preparation process.

[0067] However, compositions according to the invention can be defined relatively easily when using a limited number of 1,4:3,6-dianydrohexitol(s), primary and / or aromatic diol(s), and / or fatty acids having a C13-C29 alkyl chain. Third aspect

[0068] Thus, a third object of the invention relates to a C13-C29 alkyl diester composition comprising, by composition weight: from 35 to 85% of a C13-C29 alkyl diester of 1,4:3,6-dianydrohexitol (A), from 10 to 50%, %, of diester of a primary or aromatic diol (B), less than 6% of a C13-C29 alkyl monoester of 1,4:3,6-dianydrohexitol (C), less than 3% of fatty acid having a C13-C29 alkyl chain (D), the total content of C13-C29 alkyl diester of 1,4:3,6-dianydrohexitol (A) and of diester of a primary or aromatic diol (B) being between 80% and 99%, preferably between 90% and 99%. the total content of C13-C29 alkyl diester of 1,4:3,6-dianydrohexitol (A) and of diester of a primary or aromatic diol (B) being between 80% and 99%, preferably between 90% and 99%.

[0069] The 1,4:3,6-dianydrohexitol, the primary or aromatic diol, the fatty acid, and the esters are as defined in the first object of the invention.

[0070] The composition according to the invention has the advantage of being lightly colored.

[0071] The Applicant company has also discovered that, surprisingly, compositions comprising a mixture of C13-C29 alkyl diester of 1,4:3,6-dianydrohexitol and diester of a primary or aromatic diol exhibit performance equivalent to or even superior to compositions obtained by removing the residual fatty acid in accordance with prior art processes, by distillation or by liquid-liquid washing, and therefore comprising only one or more alkyl diesters of 1,4:3,6-dianydrohexitol, but no diester of a primary or aromatic diol.

[0072] The composition according to the invention preferably comprises 50 to 85% of diester (A).

[0073] The composition according to the invention preferably comprises 10 to 50%, more preferably 10 to 35% of diester (B).

[0074] The composition according to the invention preferably comprises less than 5%, 4%, 3%, or less than 2% of monoester (G), typically from 0.5 to 6%, typically again from 2 to 6% of monoester (C).

[0075] The composition according to the invention preferably comprises less than 2% or 1% of fatty acid (D), typically from 0.5 to 3%, typically again from 1 to 3% of fatty acid (D).

[0076] 1,4:3,6-dianydrohexitol is preferably isosorbide.

[0077] Preferably, the alkyl diester is C13-C17 and the fatty acid has a C13-C17 alkyl chain.

[0078] The primary or aromatic diol is preferably ethylene glycol.

[0079] In a preferred embodiment, the composition according to the invention comprises, by weight of composition: 35 to 85% isosorbide distearate (A), 10 to 50% ethylene glycol distearate (B), less than 6% isosorbide monostearate (C), less than 3% stearic acid.

[0080] In a preferred embodiment, the composition according to the invention comprises, by composition weight: 35 to 85% of isosorbide dimyristate (A), 10 to 50% of ethylene glycol dimyristate (B), less than 6% of isosorbide monomyristate (C), less than 3% of myristic acid.

[0081] The relative amounts of different esters and fatty acids can be determined by usual methods known to those skilled in the art, typically by gas chromatography or HPLC.

[0082] The composition may also include traces of monoester of a primary or aromatic diol (E), for example 0 to 1% preferably 0 to 0.1% monoester (E), by weight of composition.

[0083] The composition may also include traces, for example from 0 to 1%, preferably from 0 to 0.1%, preferably still from 0 to 0.01% of primary or aromatic diol (F), by composition weight.

[0084] The sum of the contents of esters (A), (B), (C), (E), fatty acids (D) and primary or aromatic diol (F) is preferably equal to 100%. APHA hair color

[0085] The composition advantageously presents an APHA color index of less than 30.

[0086] The APHA color index of the composition according to the invention is preferably between 10 and 30, more preferably between 15 and 25, and even more preferably between 18 and 22.

[0087] This is particularly advantageous for use of the composition according to the invention as an additive, typically as a flow agent in the manufacture of a transparent synthetic polymer such as polycarbonate.

[0088] In the present invention, the APHA color index is measured directly on a sample of the composition according to the procedure in ASTM D8005-18 of March 2018. It should be noted that some compositions may be in solid form with a melting point of approximately 80°C. In this case, the color index is measured according to the procedure in ASTM D8005-18 of March 2018, except that the measurement is performed at a temperature of 90°C (i.e., above the melting point of the composition) so that the composition is in liquid form. Fourth aspect

[0089] A third object of the invention relates to the use of a composition according to the second or third object of the invention in a process for preparing a synthetic polymer.

[0090] The composition according to the second or third object of the invention is preferably used as a plasticizer.

[0091] The term "plasticizer" generally refers to a product which, when mixed in sufficient quantity with a polymer, facilitates its shaping, for example by lowering the glass transition temperature of said polymer.

[0092] The composition according to the second or third object of the invention is particularly suitable for the preparation of transparent synthetic polymers, in which color is an issue, such as polycarbonate.

[0093] The composition according to the second or third object of the invention is preferably used in a process for preparing a polycarbonate, in particular during the shaping of a polycarbonate, to improve the flow of the molten material.

[0094] The polycarbonate preparation process includes at least one step of shaping a polycarbonate by extruding a mixture comprising a diester composition according to the second or third object of the invention with a polycarbonate, the mixture typically containing between 3 and 5% by weight of composition according to the second or third object of the invention.

[0095] Polycarbonate can be aliphatic or aromatic. For example, it can be aromatic, typically such as those described in patent EP 3 443 033 B1. Aromatic polycarbonate is preferably aromatic, containing monomer units of the formula -[CO-O-pR1-R2-pR1-O]. n , in which R1 represents a phenyl group possibly substituted by an alkyl group at C1-C4; R2 represents a group R3(R4R5), with R3 a carbon atom or a 6-carbon ring and R4 and R5, which may be identical or different from each other, each represent a hydrogen atom or a (R6)n group, in which R6 represents a C1-C4 alkyl, n representing 1, 2 or 3. EXAMPLES Analytical methods

[0096] Measurement of the mass quantities of esters and fatty acids

[0097] The relative proportions of each ester were measured by gas chromatography on a Varian 3400 instrument with FID detection and a split / splitless injector (type 1077). The column used was a J & W Scientific DB1, 30 meters long, with an internal diameter of 0.32 mm and a film thickness of 0.25 mm. The temperature conditions were as follows: injector and detector: 300°C; column: programmed from 100°C to 320°C at a rate of 7°C / min, held for 15 minutes at 320°C. Injection was performed in split mode at 80 ml / min, with a column head pressure of 14 psi and helium as the carrier gas.

[0098] The relative quantity of diester is given by the ratio of the sum of the areas of the compounds corresponding to the isosorbide diesters relative to an external standard, heptadecanoic acid.

[0099] APHA color measurement

[0100] The APHA color index is measured according to the procedure of the ASTM D8005-18 standard of March 2018. Example 1: Synthesis of isosorbide distearate followed by esterification of residual fatty acids by addition of ethylene glycol (ACCORDING TO THE INVENTION)

[0101] In a 2 L double-jacketed reactor, 150 g of isosorbide (1 eq) and 876 g of stearic acid (C18:0, 3 eq) were introduced. Under nitrogen purging, the reactor was heated to 90°C to melt the mixture. Once melted, a color change was observed (APHA = 17). Next, still under nitrogen purging, the following were added: 3 wt% methanesulfonic acid (relative to the isosorbide), 5 wt% hypophosphorous acid (relative to the isosorbide), and 1 wt% powdered activated carbon (relative to the total mass of the input). The mixture was heated to 160°C, and a vacuum ramp was then applied from 100 mbar to 5 mbar over 1 hour.

[0102] After 2 hours, the medium was cooled under a flow of nitrogen to 100°C. A sample was taken for analysis and showed the presence of 34% fatty acid, 2% isosorbide monoester and 64% isosorbide diester.

[0103] Then, 0.5eq of ethylene glycol (relative to isosorbide) was added to the medium. The temperature was brought back to 180°C and the medium was left to be stirred for an additional 2 hours under a vacuum of 5 mbar.

[0104] The mixture was then cooled to 100°C and brought back under nitrogen, and a stoichiometric amount of sodium hydroxide was added to neutralize the AMS and hypophosphorous acid. The reaction mixture was hot-filtered (100°C) using a Beko KD3 filter. The results are as follows (relative percentage in the composition compared to the total weight of the composition). Example 2: Synthesis of isosorbide distearate and purification via distillation (COMPARATIVE)

[0105] In a 2 L double-jacketed reactor, 150 g of isosorbide (1 eq) and 876 g of stearic acid (C18, 3 eq) were introduced. Under nitrogen purging, the reactor was heated to 90°C to melt the mixture. Once melted, a color change was recorded (APHA = 19). Next, still under nitrogen purging, the following were added: 3 wt% methanesulfonic acid (relative to the isosorbide), 5 wt% hypophosphorous acid (relative to the isosorbide), and 1 wt% powdered activated carbon (relative to the total mass of input). The mixture was heated to 160°C, and a vacuum ramp was then applied from 100 mbar to 5 mbar over 2 hours to distill the reaction water. The mixture was then cooled to 100°C and a stoichiometric amount of sodium hydroxide was added to neutralize the MSA and hypophosphorous acid. The reaction mixture was hot-filtered (100°C) through a Beko KD3 filter. Still at 100°C, 3000 ppm of Irganox 1010 was added.

[0106] The crude reaction product was distilled on a scraped film evaporator (distillation area: 0.0045m²). 2 ) at 190°C under vacuum at 0.1 mbar and at a feed rate of 1 kg / h to distill excess fatty acids. The composition of the diester in the residue is as follows (relative percentage in the composition compared to the total weight of the composition): Example 3: Variation in excess fatty acid of (Example 1 (ACCORDING TO THE INVENTION)

[0107] In a 2 L double-jacketed reactor, 150 g of isosorbide (1 eq) and 671 g of stearic acid (C18, 2.3 eq) were introduced. Under nitrogen purging, the reactor was heated to 90°C to melt the mixture. Once melted, a color change was recorded (APHA = 19). Next, still under nitrogen purging, the following were added: 3 wt% methanesulfonic acid (relative to the isosorbide), 5 wt% hypophosphorous acid (relative to the isosorbide), and 1 wt% powdered activated carbon (relative to the total mass of the input). The mixture was heated to 160°C, and a vacuum ramp was then applied from 100 mbar to 65 mbar over 2 hours.

[0108] After 2 hours, the medium was cooled under a flow of nitrogen to 100°C. Then, 0.15 eq of ethylene glycol (relative to isosorbide) was added to the medium. The temperature was raised to 180°C and the medium was stirred for another 2 hours.

[0109] The mixture is then cooled to 100°C and a stoichiometric amount of sodium hydroxide is added to neutralize the AMS and hypophosphorous acid. The reaction mixture is hot-filtered (100°C) using a Beko KD3 filter. The results are as follows (relative percentage in the composition compared to the total weight of the composition): Example 4: Direct incorporation of the second diol, non-sequenced esterification (COMPARATIVE):

[0110] In a 2 L double-jacketed reactor, 150 g of isosorbide (1 eq) is introduced, along with 671 g of stearic acid (C18, 2.3 eq) and 0.15 eq of ethylene glycol. Under nitrogen purging, the reactor is heated to 90°C to melt the mixture. Once melted, a color change is observed (APHA = 19). Next, still under nitrogen purging, 3 wt% of methanesulfonic acid (relative to the isosorbide), 5 wt% of hypophosphorous acid (relative to the isosorbide), and 1 wt% (relative to the total mass of input) of powdered activated carbon are introduced. The mixture is heated to 160°C, and a vacuum ramp is then applied from 100 mbar to 5 mbar over 4 hours.

[0111] The mixture is then cooled to 100°C and a stoichiometric amount of sodium hydroxide is added to neutralize the MSA and hypophosphorous acid. The reaction mixture is hot-filtered (100°C) using a Beko KD3 filter. The following results are obtained (relative percentage in the composition):

[0112] The direct incorporation of the second diol at the start is accompanied by an increase in monoester and a higher residual fatty acid content. Example 5: Synthesis of an isosorbide myristate composition (ACCORDING TO THE INVENTION)

[0113] Example 1 was reproduced by replacing stearic acid with myristic acid (C14:0). The results are as follows:

[0114] The composition of the medium is as follows (relative percentage in the composition compared to the total weight of the composition): Example 6: Synthesis of isosorbide dimyristate and purification via distillation (COMPARATIVE)

[0115] A comparative example identical to example 2 was carried out except that stearic acid (C18:0) was replaced by myristic acid (C14:0). The results after distillation are as follows (relative percentage in the composition compared to the total weight of the composition): Example 7: (ACCORDING TO THE INVENTION)

[0116] Example 2 was reproduced by replacing ethylene glycol with cyclohexanedimethanol (CHDM). The results are as follows (relative percentage in the composition compared to the total weight of the composition):

[0117] Example 8 (ACCORDING TO THE INVENTION):

[0118] Example 2 was reproduced by replacing ethylene glycol with neopentyl glycol (NPG). The results are as follows (relative percentage in the composition compared to the total weight of the composition): Example 9 (ACCORDING TO THE INVENTION):

[0119] Example 2 was reproduced by replacing ethylene glycol with 1,4-butanediol. The results are as follows (relative percentage in the composition compared to the total weight of the composition):

[0120] Example 10 (ACCORDING TO THE INVENTION):

[0121] Example 2 was reproduced by replacing ethylene glycol with 1,4-benzenedimethanol. The results are as follows (relative percentage in the composition compared to the total weight of the composition): Example 11 (ACCORDING TO THE INVENTION):

[0122] Example 2 was reproduced by replacing ethylene glycol with resorcinol. The results are as follows (relative percentage in the composition compared to the total weight of the composition):

[0123] Example 12: Use in a polycarbonate preparation process (ACCORDING TO THE INVENTION)

[0124] The diester compositions of Examples 1, 3, 5 and 7 to 11 (ACCORDING TO THE INVENTION) were used in a process for preparing polycarbonate.

[0125] A mixture comprising polycarbonate and approximately 0.5% of a diester composition, % by weight of mixture, was extruded.

[0126] The compositions of Examples 1, 3, 5, and 7 through 11 (according to the invention) have proven effective in improving the flow of molten polycarbonate. For example: In the case of the composition from Examples 1 and 3, the melt flow index (MFI) was determined according to ISO 1133 using a dedicated apparatus (CEAST brand, model 7024). The extruded polycarbonate without additives has an MFI of 12.9 g / 10 min. The same polycarbonate with 0.5% of the composition from Example 1 has an MFI of 43.5 g / 10 min. The same polycarbonate with 0.5% of the composition from Example 3 has an MFI of 42.75 g / 10 min.

[0127] Furthermore, no yellowing of the final product was observed. Example 13: Use in a polycarbonate preparation process (COMPARATIVE)

[0128] A C8 / C10 alkyl isosorbide diester composition marketed by the Applicant under the name Polysorb ID46 was used in a polycarbonate preparation process.

[0129] The composition of Polysorb ID46 did not improve the flow of the molten polycarbonate. It appears that the diesters are vaporized during forming due to excessively short alkyl chains. For example, extruded polycarbonate without the additive has a flow rate of 12.9 g / 10 min. The same polycarbonate with 0.5% Polysorb ID46 added has a flow rate of 15.7 g / 10 min.

[0130] The polycarbonate obtained after extrusion has an undesirable yellow color.

Claims

DEMANDS

1. A process for preparing a C13-C29 alkyl diester composition of 1,4:3,6-dianydrohexitol, said process comprising: a) a first step of esterifying 1,4:3,6-dianydrohexitol with a fatty acid having a C13-C29 alkyl chain, said fatty acid being in excess, so as to form a crude reaction comprising a C13-C29 alkyl diester of 1,4:3,6-dianydrohexitol and unreacted fatty acid; b) a second step of esterifying the unreacted fatty acid with a primary or aromatic diol.

2. A method according to claim 1, wherein 1,4:3,6-dianhydrohexitol is selected from isosorbide, isomannide, isoidide, or a mixture thereof.

3. A method according to any one of claims 1 or 2, wherein the fatty acid is selected from stearic acid, myristic acid, palmitic acid, isopalmitic acid, margaric acid, tuberculostearic acid, lactobacillic acid, arachidic acid, phytanic acid, chaulmoogric acid, 11-cyclohexylundecanoic acid or a mixture thereof.

4. A process according to any one of claims 1 to 3, wherein the primary or aromatic diol is selected from ethylene glycol, cyclohexanedimethanol (CHDM), neopentyl glycol (NPG), 1,4-butanediol, 1,4-benzenedimethanol, resorcinol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decandiol, 1,12-dodecanediol or a mixture thereof.

5. A process according to any one of claims 1 to 4, wherein the first and second esterification steps are carried out in the presence of an acid catalyst.

6. C13-C29 alkyl diester composition of 1,4:3,6-dianydrohexitol capable of being obtained according to the process of any one of claims 1 to 5.

7. Composition of a C13-C29 alkyl diester of 1,4:3,6-dianydrohexitol comprising, by composition weight: from 35 to 90% of a C13-C29 alkyl diester of 1,4:3,6-dianydrohexitol (A), from 10 to 50% primary or aromatic diol diester (B), less than 6% C13-C29 alkyl monoester of 1,4:3,6-dianydrohexitol (C), less than 3% fatty acid having a C13-C29 alkyl chain (D), the total content of C13-C29 alkyl diester of 1,4:3,6-dianydrohexitol (A) and primary or aromatic diol diester (B) being between 80% and 99%, preferably between 90% and 99%.

8. Composition according to any one of claims 6 or 7, wherein 1,4:3,6-dianydrohexitol is the isosorbide.

9. Composition according to any one of claims 6 to 8, wherein the alkyl diester is in C13-C17 and the fatty acid has an alkyl chain in C13-C17.

10. Composition according to any one of claims 6 to 9, wherein the primary or aromatic diol is ethylene glycol.

11. Composition according to any one of claims 6 to 10 comprising, by composition weight: 35 to 90% isosorbide distearate (A), 10 to 50% ethylene glycol distearate (B), less than 6% isosorbide monostearate (C), less than 3% stearic acid (D).

12. Composition according to any one of claims 6 to 10 comprising, by composition weight: 35 to 90% isosorbide dimyristate (A), 10 to 50% ethylene glycol dimyristate (B), less than 6% isosorbide monosmyristate (C), less than 3% myristic acid (D).

13. Composition according to any one of claims 6 to 12, which has an APHA colour index of less than 30.

14. Use of a composition according to any one of claims 6 to 13 in a process for preparing a polycarbonate, in particular during its shaping, to improve the flow of a polycarbonate melt.

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