Process for preparation of 1, 4: 3, 6-dianhydrohexitol diester compositions

Abstract

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

Description

Technical Field

[0001] The present invention relates to a method for preparing a 1,4:3,6-dianhydrohexitol alkyl diester composition and the use of the composition in preparing polycarbonate, in particular to the use of the composition for improving the melt flow of polycarbonate. Prior art

[0002] It is known that alkyl diesters of 1,4:3,6-dianhydrohexitols, such as isosorbide, can be added to polymers to facilitate their shaping. They then act as "plasticizers".

[0003] The most commonly used plasticizers today belong to the family of phthalates (ortho-phthalates). Phthalates are readily available on the market at low cost, but are being replaced due to toxicity issues.

[0004] For example, patent EP 3 443 033 B1 describes that C8 / C10 alkyl diesters of isosorbide, sold by the applicant under the trade name Polysorb ID46, facilitate the preparation of polycarbonates, in particular by improving their melt flow.

[0005] 1,4:3,6-dianhydrohexitol alkyl diesters are conventionally prepared by esterifying 1,4:3,6-dianhydrohexitol with excess fatty acid, usually in the presence of an acidic catalyst. The crude reaction product contains unreacted fatty acid (residual fatty acid). Since such fatty acid has a negative impact on the use of the diester composition as a plasticizer, the fatty acid is removed at the end of the esterification step by subjecting the crude reaction product to a distillation step or a liquid-liquid washing step (including washing with water in the presence of a weak base such as sodium bicarbonate), followed by a drying step.

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

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

[0008] In the course of its research, the applicant company found that in the polycarbonate preparation process, C8 / C10 alkyl diesters did not have the expected effect and additionally imparted coloration to the polycarbonate. New long-chain alkyl diesters of 1,4:3,6-dianhydrohexitol have been developed. During the development process, it was found that the application of a residual fatty acid removal step by liquid-liquid distillation or washing resulted in the degradation of part of the diester to monoesters and yellowing of the product.

[0009] It is therefore necessary to find a process which makes it possible to prepare compositions of long-chain alkyl diesters of 1,4:3,6-1,4:3,6-dianhydrohexitol with low coloration and minimal residual fatty acid content on an industrial scale in good yields, which compositions can be used in the preparation of polycarbonates, in particular in their molding processes. DETAILED DESCRIPTION

[0010] First aspect

[0011] According to a first aspect, the present invention relates to a method for preparing a composition of C13-C29 alkyl diesters of 1,4:3,6-dianhydrohexitol, the method comprising:

[0012] a) in a first step, 1,4:3,6-dianhydrohexitol is esterified with a fatty acid having a C13-C29 alkyl chain, the fatty acid being in excess, to form a crude reaction product comprising a C13-C29 alkyl diester of 1,4:3,6-dianhydrohexitol and unreacted fatty acid;

[0013] b) In the second step, the unreacted fatty acid is esterified with a primary diol or an aromatic diol.

[0014] As mentioned above, the Applicant Company has found that when the composition obtained by esterifying 1,4:3,6-dianhydrohexitol with long-chain fatty acids is purified by distillation, the resulting composition exhibits an undesirable coloration. As regards liquid-liquid washing, the Applicant Company has observed that the drying step applied after washing with water in the presence of a weak base produces coloration. It has also been found that in the case of saturated fatty acids, the resulting reaction crude product is solid and can only be washed at a temperature above its melting temperature (typically above 80° C.), which results in partial hydrolysis of the 1,4:3,6-dianhydrohexitol diesters.

[0015] Without wishing to be bound by any particular theory, the inventors believe that in prior art processes the risk of cleavage of the diester to the monoester increases with the temperature applied during removal by distillation or liquid-liquid washing, the risk being higher the longer the alkyl chain.

[0016] The present inventors have developed a process in which, unlike prior art processes, the removal of residual fatty acids does not require liquid-liquid distillation or washing.

[0017] The process according to the invention is easy to implement on an industrial scale and is cost-effective.The process is based on two consecutive esterification steps.

[0018] The first step involves the esterification of 1,4:3,6-dianhydrohexitol with a long-chain fatty acid in excess to obtain as much diester as possible.

[0019] The second step involves esterification of the residual fatty acid with a primary or aromatic diol to remove most, nearly all, or even all of the fatty acid that was unreacted in the first esterification step.

[0020] This elimination by esterification has the advantage of being easier to carry out than elimination by distillation and can be carried out directly in the esterification reactor used for the first esterification step.

[0021] Thus, the process according to the invention is advantageously a single-stage process, ie a preparation process whose various stages are carried out successively in the same reactor. The process according to the invention advantageously does not comprise an isolation, separation or purification step by evaporation, for example by distillation.

[0022] Furthermore, as will be described in detail below, the composition obtained by the process according to the present invention exhibits low coloration and is effective in the polycarbonate preparation process.

[0023] "C13-C29 alkyl diester" refers to an alkyl diester of 1,4:3,6-dianhydrohexitol, wherein an alkyl group is bonded to the hydroxyl group of 1,4:3,6-dianhydrohexitol. This C13-C29 alkyl diester is produced by the esterification reaction of 1,4:3,6-dianhydrohexitol with a fatty acid. The esterification reaction can be written as follows: R-OH+HO(O)C-R'=>RO(O)C-R'+H2O. Therefore, 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. If only one of the two alcohol functional groups of the diol has been reacted by the esterification reaction, the ester is a monoester. If both alcohol functional groups of the diol have been reacted in the esterification reaction, it is a diester. When the C13-C29 alkyl diester of 1,4:3,6-dianhydrohexitol is obtained using two different fatty acids, the diester may include different alkyl groups.

[0024] For the purposes of the present invention, the expression "fatty acid with C13-C29 alkyl chain" refers to a fatty acid R'-COOH comprising 14 to 30 carbon atoms, one carbon atom belonging to a carboxylic acid group (-COOH), and the remaining carbon atoms belonging to a substituted or unsubstituted straight or branched alkyl chain comprising 13 to 29 carbon atoms, or a mixture thereof. Preferably, the alkyl chain is saturated. The alkyl chain may be substituted by a group comprising at least one heteroatom selected from oxygen and nitrogen, preferably a ketone or hydroxyl group or an amido group. The chain may be substituted at the end of the alkyl chain by a cyclic group generally containing 5 to 12 carbon atoms, preferably 6 to 10 carbon atoms, preferably, the chain may be substituted at the end of the alkyl chain by a cyclohexane ring or a cyclopentane ring, or by a C2-C4 alkyl chain connected to the fatty acid alkyl chain at two attachment points, thereby forming an intrachain ring, preferably, forming an intrachain cyclopropane.

[0025] Step a)

[0026] In the first step, 1,4:3,6-dianhydrohexitol is esterified with a fatty acid having a C13-C29 alkyl chain.

[0027] 1,4:3,6-II Dehydration Hexitol

[0028] 1,4:3,6-dianhydrohexitol is a dianhydrohexitol with the empirical formula C6H 10 O4 diol.

[0029] The present invention uses three isomers of 1,4:3,6-dianhydrohexitol: isosorbide, isomannide and isoidide, or a mixture thereof.

[0030] Preferred is isosorbide.

[0031] fatty acid

[0032] Preferably, the fatty acid has a C13-C29, preferably C13-C17 alkyl chain.

[0033] By way of example, the fatty acid may be selected from stearic acid (octadecanoic acid C18:0), myristic acid (tetradecanoic acid C14:0), palmitic acid (hexadecanoic acid C16:0), isopalmitic acid (14-methylpentadecanoic acid), nacreous acid (heptadecanoic acid C17:0), tuberostearic acid (10-methylstearic acid), lactobacillus acid (10-[(1R,2S)-2-hexylcyclopropyl]decanoic acid), arachidic acid (eicosanoic acid C20:0), phytanic acid (3,7,11,15-tetramethylhexadecanoic acid), 11-cyclohexylundecanoic acid (11-cyclohexylundecanoic acid), or mixtures thereof.

[0034] The fatty acid is advantageously a C16 or C18 fatty acid, or a mixture thereof.

[0035] Preferred are stearic acid and myristic acid.

[0036] Excess fatty acids

[0037] In the first step, the fatty acid having a C13-C29 alkyl chain is in excess relative to the 1,4:3,6-dianhydrohexitol to promote the formation of the C13-C29 alkyl diester of the 1,4:3,6-dianhydrohexitol and minimize the formation of the corresponding monoester.

[0038] "Excess" means a stoichiometric excess, i.e. the amount of fatty acid having a C13-C29 alkyl chain is greater than the stoichiometric amount required for the esterification reaction with all the hydroxyl groups of the 1,4:3,6-dianhydrohexitol present. In other words, in the first step of the method according to the invention, 2y+z moles of fatty acid are preferably reacted with y moles of 1,4:3,6-dianhydrohexitol, wherein y and z are in moles, 2y represents the stoichiometric amount of fatty acid relative to y moles of 1,4:3,6-dianhydrohexitol, and z represents the amount of excess fatty acid relative to the stoichiometric amount. The stoichiometric excess of fatty acid relative to 1,4:3,6-dianhydrohexitol can also be expressed as a percentage using the formula (z / 2y+z)x100.

[0039] Preferably, the fatty acid is in a stoichiometric excess of 10% to 100% relative to the 1,4:3,6-dianhydrohexitol. Preferably, 2.2 to 4 moles of fatty acid are reacted per mole of 1,4:3,6-dianhydrohexitol.

[0040] In other words, 1,4:3,6-dianhydrohexitol is preferably reacted with fatty acid at a 1,4:3,6-dianhydrohexitol / fatty acid molar ratio of 1 / 2.2 to 1 / 4.

[0041] Reaction crude product

[0042] For the purposes of the present invention, "reaction crude product" means the product of the first step of esterification of 1,4:3,6-dianhydrohexitol with fatty acids having a C13-C29 alkyl chain, and preferably no step of removing residual fatty acids is applied, in particular no step of isolation, separation or purification is applied, in particular no step of removing unreacted fatty acids by distillation or liquid-liquid route is applied.

[0043] Preferably, the crude reaction product contains alkyl diester of 1,4:3,6-dianhydrohexitol, alkyl monoester of 1,4:3,6-dianhydrohexitol and unreacted fatty acid.

[0044] Step b)

[0045] In the second step, the fatty acid which has not reacted in the first step is esterified with a primary diol or an aromatic diol to remove as much of the fatty acid as possible from the crude reaction product.

[0046] The primary or aromatic diol has a higher reactivity than the 1,4:3,6-dianhydrohexitol from step a). Preferably, it is not transesterified with the C13-C29 alkyl diester of the 1,4:3,6-dianhydrohexitol of the crude reaction product obtained after step a).

[0047] Primary diol or aromatic diol

[0048] "Diol" means a compound containing two hydroxyl (-OH) groups. Preferably, the compound is a hydrocarbon structure generally containing from 2 to 20 carbon atoms, preferably from 2 to 12 carbon atoms.

[0049] The diol used in step b) is a primary diol or an aromatic diol.

[0050] "Primary diol" means a diol whose hydroxyl group is carried by a carbon atom which also carries at least 2 hydrogen atoms.

[0051] "Aromatic diol" means a diol whose hydroxyl groups are carried by carbon atoms of an aromatic ring.

[0052] "Aromatic ring" means a polyunsaturated cyclic hydrocarbon structure, wherein the ring structure is planar and has (4n+2) delocalized electrons, n is an integer, having a single ring or multiple rings fused together and generally containing 5 to 12 carbon atoms, preferably 6 to 10 carbon atoms. The preferred aromatic ring is phenyl.

[0053] The primary diol preferably contains 2 to 20 carbon atoms, more preferably 2 to 15 carbon atoms.

[0054] For example, the primary or aromatic diol can be selected 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-decanediol, 1,12-dodecanediol, or mixtures thereof.

[0055] Ethylene glycol is preferred.

[0056] In the second step, preferably, the primary or aromatic diol is introduced in a stoichiometric proportion or in a slight under-proportion relative to the fatty acids that were not reacted in the first step, in order to eliminate substantially all of such fatty acids. Without wishing to be bound by any particular theory, the inventors hypothesize that if the primary or aromatic diol is added in a stoichiometric excess relative to the residual fatty acids, the final composition runs the risk of containing monoesters of the primary or aromatic diol, which carries the risk of transesterification and thus produces 1,4:3,6-dianhydrohexitol monoesters.

[0057] "Slightly insufficient proportion of primary or aromatic diol relative to the fatty acid unreacted in the first step" means stoichiometric deficiency, i.e., the amount of primary or aromatic diol is slightly less than the stoichiometric amount required for esterification of all hydroxyl groups of the fatty acid unreacted in the first step.

[0058] The first esterification step generally comprises reacting 0.45 to 0.5 moles of primary or aromatic diol per mole of excess fatty acid. Typically, when the first esterification reaction in step a) is carried out with a molar amount of fatty acid in excess relative to the stoichiometric amount (which, as detailed above, can be indicated as "z"), the second esterification reaction in step b) is carried out with a molar amount of primary diol corresponding to a molar amount between 45% and 50% of the fatty acid used in excess relative to the stoichiometric amount in step a). By way of example, if 2.3 moles of fatty acid are introduced per mole of 1,4:3,6-dianhydrohexitol in step a) (i.e. excess z=0.3 moles of fatty acid), then in step b) preferably 0.3×45%=0.135 to 0.3×50% (i.e. 0.3 / 2)=0.15 moles of primary or aromatic diol.

[0059] Esterification conditions

[0060] The esterification step can be carried out under conventional conditions already used in the literature. These esterification processes are described, for example, in documents WO 99 / 45060 A1 or WO 2006 / 103338 A1.

[0061] The esterification step is preferably carried out in the presence of at least one acid catalyst.

[0062] The acid catalyst used can be of very different nature, for example being chosen from hypophosphorous acid, hydrochloric acid, sulfuric acid, p-toluenesulfonic acid (APTS), methanesulfonic acid (AMS), trifluoromethanesulfonic acid, trifluoroacetic acid, trichloroacetic acid, 2-ethyltin hexanoate, phosphotungstic acid, and silicotungstic acid, or mixtures of these acids, or an acid catalyst of a macroporous or non-macroporous resin comprising at least one of these acids.

[0063] In the case of a mixture of acid catalysts, they may or may not be introduced into the reaction medium simultaneously.

[0064] The mass of the acid catalyst may be 0.05% to 20%, such as 0.1% to 10%, of the mass of the 1,4:3,6-dianhydrohexitol introduced into the reactor.

[0065] It should be noted that hypophosphorous acid can also act as a color reducing agent. It can be introduced into the reaction medium simultaneously or not with another acid catalyst and / or fatty acid. According to a variation, the introduction is carried out before or at the beginning of the esterification reaction, i.e. before the introduction of the acid catalyst and / or fatty acid. Advantageously, whenever introduced, hypophosphorous acid is introduced in an amount of 0.05% to 2%, preferably 0.1% to 1%, based on the dry weight of the 1,4:3,6-dianhydrohexitol used. According to another variation, whether or not simultaneously with the acid esterification catalyst, hypophosphorous acid is introduced with a hypophosphorous acid / acid catalyst ratio of less than 1 / 1, the ratio being expressed as the dry weight of hypophosphorous acid relative to the dry weight of the acid catalyst. In particular, the ratio may be 0.01 / 1 to 0.9 / 1, preferably 0.02 / 1 to 0.8 / 1. When the catalyst is APTS, methanesulfonic acid or phosphotungstic acid, the ratio may advantageously be 0.05 / 1 to 0.4 / 1.

[0066] The temperature in the reactor may be from 90°C to 200°C, typically from 100°C to 160°C. For the esterification reaction, water is typically removed, for example by distillation of the reaction medium, to promote diester formation. To promote this removal, the reaction medium may be placed under vacuum, for example at a level of from 10 mbar to 200 mbar. Reaction conditions such as vacuum and temperature may vary during the reaction.

[0067] The first esterification step is generally continued for the time taken to achieve satisfactory conversion to the 1,4:3,6-dianhydrohexitol diester. This may vary widely, from 1 to 10 hours.

[0068] The second esterification stage usually lasts until the free fatty acids have been satisfactorily eliminated. This can vary widely, from 1 to 10 hours.

[0069] A neutralization step can also be carried out on the introduced catalyst by introducing a base, such as soda ash, in a molar amount equal to the molar amount of the introduced catalyst. This neutralization step is preferably carried out after the second esterification step.

[0070] Color reducing agent

[0071] The process according to the invention may further comprise a step for decolorizing the crude reaction product from step a) using a decolorizing agent such as activated carbon or hydrogen peroxide or a bleaching earth such as bleaching clay, bentonite or montmorillonite.

[0072] This step can be carried out continuously after one of steps a) and / or b). In this embodiment, the decolorizing agent is added after one of steps a) and / or b).

[0073] This step can also be carried out simultaneously with step a) and / or b). In this embodiment, the decolorizing agent is added after one of steps a) and / or b) has been started.

[0074] The treatment with activated carbon is carried out, for example, by contacting the reaction crude with 1 to 5% by weight of activated carbon. The temperature during this treatment may be about 100° C. The duration is generally several tens of minutes, for example about one hour. At the end of the treatment, the activated carbon is separated by filtration. The treatment with bleaching earth is similar to the treatment with activated carbon.

[0075] Conventional hydrogen peroxide decolorization treatments involve, for example, introducing 0.5% to 2% of 100% hydrogen peroxide into the composition to be decolorized over a period of 30 to 60 minutes at a temperature between 90° C. and 100° C., and then stirring the composition at that temperature for 1 to 2 hours. When it is desired to combine these two types of decolorization treatments, hydrogen peroxide treatment is preferred over activated carbon treatment.

[0076] Preferred Implementation

[0077] In a preferred embodiment, the process according to the invention makes it possible to prepare a composition of C13-C29 alkyl diesters of isosorbide, the process comprising:

[0078] a) in a first step, isosorbide is esterified with an excess of fatty acid having a C13-C29 alkyl chain, for example at an isosorbide / fatty acid molar ratio of 1 / 2.3 to 1 / 3, to form a crude reaction product comprising an alkyl diester of isosorbide and unreacted fatty acid;

[0079] b) in a second step, the unreacted fatty acid is esterified with a primary or aromatic diol, preferably ethylene glycol,

[0080] The fatty acids having C13-C29 alkyl chains are preferably C13, C14, C15,

[0081] Fatty acids with C16, C17 or C18 alkyl chains.

[0082] Second aspect

[0083] The second object of the present invention relates to a C13-C29 alkyl diester composition of 1,4:3,6-dianhydrohexitol obtainable by the process of the first object of the present invention.

[0084] In fact, when the diester composition is obtained from different 1,4:3,6-dianhydrohexitols, different primary and / or aromatic diols, and / or different fatty acids with a C13-C29 alkyl chain, very complex and varied compositions are obtained, which can only be more satisfactorily defined by the preparation process.

[0085] However, when using limited amounts of 1,4:3,6-dianhydrohexitols, primary and / or aromatic diols, and / or fatty acids with a C13-C29 alkyl chain, the composition according to the invention can be defined relatively easily.

[0086] The third aspect

[0087] Therefore, a third object of the present invention relates to a C13-C29 alkyl diester composition comprising, by weight of the composition:

[0088] - 35 to 85% of C13-C29 alkyl diester of 1,4:3,6-dianhydrohexitol (A),

[0089] - 10 to 50% of diesters of primary or aromatic diols (B),

[0090] - less than 6% of C13-C29 alkyl monoesters of 1,4:3,6-dianhydrohexitol (C),

[0091] - less than 3% of fatty acids with a C13-C29 alkyl chain (D),

[0092] The total content of the C13-C29 alkyl diester of 1,4:3,6-dianhydrohexitol (A) and the diester of primary or aromatic diol (B) is 80 to 99%, preferably 90 to 99%.

[0093] The total content of the C13-C29 alkyl diester of 1,4:3,6-dianhydrohexitol (A) and the diester of primary or aromatic diol (B) is 80 to 99%, preferably 90 to 99%.

[0094] 1,4:3,6-dianhydrohexitol, primary or aromatic diol, fatty acid and ester are as defined in the first object of the present invention.

[0095] The compositions according to the invention have the advantage of being light-colored.

[0096] The Applicant Company has also surprisingly found that a composition comprising a mixture of C13-C29 alkyl diesters of 1,4:3,6-dianhydrohexitol and diesters of primary or aromatic diols shows comparable or even superior performance to a composition obtained by removing residual fatty acids by distillation or liquid-liquid washing according to the prior art methods, thus comprising only one or more alkyl diesters of 1,4:3,6-dianhydrohexitol, but no diesters of primary or aromatic diols.

[0097] The composition according to the invention preferably comprises from 50% to 85% of diester (A).

[0098] The composition according to the invention preferably comprises from 10% to 50%, more preferably from 10% to 35% of diester (B).

[0099] The composition according to the invention preferably comprises less than 5%, 4%, 3% or less than 2% of monoester (C), typically from 0.5% to 6%, even more typically from 2% to 6% of monoester (C).

[0100] The composition according to the invention preferably comprises less than 2% or 1% fatty acid (D), typically 0.5 to 3%, even more typically 1 to 3% fatty acid (D).

[0101] The 1,4:3,6-dianhydrohexitol is preferably isosorbide.

[0102] Preferably, the alkyl diester is C13-C17 and the fatty acid has a C13-C17 alkyl chain.

[0103] The primary or aromatic diol is preferably ethylene glycol.

[0104] In a preferred embodiment, the composition according to the invention comprises, by weight of the composition:

[0105] - 35% to 85% of isosorbide distearate (A),

[0106] - 10% to 50% of ethylene glycol distearate (B),

[0107] - less than 6% of isosorbide monostearate (C),

[0108] - Less than 3% stearic acid.

[0109] In a preferred embodiment, the composition according to the invention comprises, by weight of the composition:

[0110] - 35% to 85% of isosorbide dimyristate (A),

[0111] - 10% to 50% of ethylene glycol dimyristate (B),

[0112] - less than 6% of isosorbide monomyristate (C),

[0113] - Less than 3% myristic acid.

[0114] The relative amounts of the various esters and fatty acids can be determined by standard methods known to those skilled in the art, typically by gas chromatography or HPLC.

[0115] The composition may also contain trace amounts of monoesters (E) of primary or aromatic diols, for example 0% to 1%, preferably 0% to 0.1% of monoesters (E) by weight of the composition.

[0116] The composition may also comprise trace amounts, for example 0% to 1%, preferably 0% to 0.1%, even more preferably 0% to 0.01% by weight of the composition, of primary or aromatic diols (F).

[0117] The sum of the contents of ester (A), (B), (C), (E), fatty acid (D) and primary or aromatic diol (F) is preferably 100%.

[0118] APHA Coloring

[0119] The composition advantageously has an APHA tint index of less than 30.

[0120] The APHA tint index of the composition according to the invention is preferably from 10 to 30, more preferably from 15 to 25, more preferably from 18 to 22.

[0121] This is particularly advantageous for using the composition according to the invention as additive, typically as flow agent in the production of transparent synthetic polymers such as polycarbonate.

[0122] 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, March 2018. It should be noted that some compositions may be in solid form with a melting point of about 80° C. In this case, the color index is measured according to ASTM D8005-18, 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.

[0123] The fourth aspect

[0124] 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.

[0125] The composition according to the second object or the third object of the present invention is preferably used as a plasticizer.

[0126] "Plasticizer" generally means a product that, when mixed in sufficient amounts with a polymer, facilitates its shaping, for example by lowering the glass transition temperature of the polymer.

[0127] The compositions according to the second or third object of the invention are particularly useful in the preparation of transparent synthetic polymers where color is a problem, such as polycarbonate.

[0128] The composition according to the second object or the third object of the present invention is preferably used in a method for preparing polycarbonate, especially in a molding process of polycarbonate, to improve melt flow.

[0129] The method for preparing polycarbonate comprises at least one step of forming polycarbonate by extruding a mixture comprising a diester composition according to the second or third object of the present invention and polycarbonate, the mixture typically containing between 3% and 5% by weight of the composition according to the second or third object of the present invention.

[0130] The polycarbonate may be an aliphatic polycarbonate or an aromatic polycarbonate. For example, the polycarbonate may be an aromatic polycarbonate, typically such as those described in patent EP 3 443 033 B1. The aromatic polycarbonate is preferably a polycarbonate containing the formula -[CO-0-pR1-R2-pR1-O] n An aromatic polycarbonate of monomer units of , wherein R1 represents a phenyl group optionally substituted by a C1-C4 alkyl group; R2 represents a group R3(R4R5), wherein R3 is a carbon atom or a ring having 6 carbon atoms, and R4 and R5 may be the same as or different from each other and each represents a hydrogen atom or a group (R6)n, wherein R6 represents a C1-C4 alkyl group and n represents 1, 2 or 3.

[0131] Example

[0132] Analytical methods

[0133] Measurement of ester and fatty acid mass

[0134] The relative proportion of each ester was measured by gas chromatography on a Varian 3400 with FID detection and a model 1077 split / splitless injector. The column used was a DB1 from JW Scientific, 30 meters long, 0.32 mm inner diameter, 0.25 mm film thickness. The temperature conditions were: injector and detector: 300°C; column: programmed from 100°C to 320°C at 7°C / min, held at 320°C for 15 min. Injection was carried out in split mode at 80 ml / min, column pressure head was 14 psi, and helium was used as carrier gas.

[0135] The relative amount of diesters is given by the ratio of the sum of the areas of compounds corresponding to isosorbide diesters to the external standard (ie heptadecanoic acid).

[0136] APHA coloration measurement

[0137] APHA Color Index is measured according to ASTM D8005-18, March 2018.

[0138] Example 1: Synthesis of isosorbide distearate followed by esterification of residual fatty acids by addition of ethylene glycol (According to the present invention)

[0139] In a 2L jacket reactor, 150g of isosorbide (1 equivalent) and 876g of stearic acid (C18:0, 3 equivalents) were introduced. Under nitrogen purge, the reactor was heated to 90°C to melt the medium. When the medium was melted, dyeing (APHA=17) was performed. Then the following substances were introduced still under nitrogen: 3% methanesulfonic acid (relative to isosorbide) by mass, 5% hypophosphorous acid (relative to isosorbide) by mass, and 1% powdered activated carbon (relative to the total mass of the feed) by mass. The medium was heated to 160°C, and then a vacuum gradient from 100mbar to 5mbar was applied in 1 hour.

[0140] After 2 hours, the medium was cooled to 100° C. under a stream of nitrogen. A sample was taken for analysis, which showed the presence of 34% fatty acids, 2% isosorbide monoesters and 64% isosorbide diesters.

[0141] 0.5 equivalent of ethylene glycol (relative to isosorbide) is then added to the medium. The temperature is lowered to 180° C. and the medium is stirred for a further 2 hours under a vacuum of 5 mbar.

[0142] The medium is then cooled to 100° C. and returned to nitrogen, a stoichiometric amount of sodium hydroxide is added to neutralize the AMS and hypophosphorous acid. The reaction medium is filtered hot (100° C.) on a Beko KD3 filter. The results are as follows (relative % in the composition compared to the total weight of the composition):

[0143]

[0144] Example 2: Synthesis and distillation purification of isosorbide distearate (comparative example)

[0145] In a 2L jacketed reactor, 150 g of isosorbide (1 equivalent) and 876 g of stearic acid (C18, 3 equivalents) are introduced. Under nitrogen purge, the reactor is heated to 90°C to melt the medium. Once the medium has melted, dyeing is performed (APHA=19). Then, still under nitrogen, 3% by mass of methanesulfonic acid (relative to isosorbide), 5% by mass of hypophosphorous acid (relative to isosorbide), and 1% by mass of powdered activated carbon are introduced. The medium is heated to 160°C (relative to the total mass of the feed) and a vacuum gradient from 100 mbar to 5 mbar is applied for 2 hours to distill the reaction water. The medium is then cooled to 100°C and a stoichiometric amount of sodium hydroxide is added to neutralize AMS and hypophosphorous acid. The reaction medium is hot filtered (100°C) on a Beko KD3 filter. Still at 100°C, 3000 ppm of Irganox 1010 are added.

[0146] The crude product was evaporated in a wiper film evaporator (distillation area: 0.0045 m 2 ) was distilled at 190° C. in vacuum at 0.1 mbar and at a feed rate of 1 Kg / h to distill off excess fatty acids. The composition of the diesters in the residue was as follows (relative % in the composition relative to the total weight of the composition):

[0147]

[0148] Example 3: Modification of the fatty acid excess of Example 1 (according to the present invention)

[0149] In a 2L jacketed reactor, 150 g of isosorbide (1 equivalent) and 671 g of stearic acid (C18, 2.3 equivalents) are introduced. Under nitrogen purge, the reactor is heated to 90° C. to melt the medium. Once the medium has melted, dyeing (APHA=19) is performed. The following substances are then introduced, still under nitrogen: 3% methanesulfonic acid (relative to isosorbide), 5% hypophosphorous acid (relative to isosorbide) by mass, and 1% powdered activated carbon (relative to the total mass of the feed) by mass. The medium is heated to 160° C., and a vacuum gradient from 100 mbar to 65 mbar is then applied over 2 hours.

[0150] After 2 hours, the medium is cooled to 100° C. under a stream of nitrogen. 0.15 equivalents of ethylene glycol (relative to isosorbide) are then added to the medium. The temperature is lowered to 180° C. and the medium is stirred for a further 2 hours.

[0151] The medium is then cooled to 100° C. and a stoichiometric amount of sodium hydroxide is added to neutralize the AMS and hypophosphorous acid. The reaction medium is filtered hot (100° C.) on a Beko KD3 filter. The results are as follows (relative % in the composition compared to the total weight of the composition):

[0152]

[0153] Example 4: Direct introduction of the second diol, non-sequential esterification (comparative example) :

[0154] In a 2L jacketed reactor, 150g of isosorbide (1 equivalent) was introduced with 671g of stearic acid (C18, 2.3 equivalents) and 0.15 equivalents of ethylene glycol. Under nitrogen purge, the reactor was heated to 90°C to melt the medium. When the medium was melted, dyeing (APHA=19) was performed. Then, still under nitrogen, 3% by mass of methanesulfonic acid (relative to isosorbide), 5% by mass of hypophosphorous acid (relative to isosorbide), and 1% by mass (relative to the total input mass) of powdered activated carbon were introduced. The medium was heated to 160°C and then a vacuum gradient from 100mbar to 5mbar was applied over 4 hours.

[0155] The medium is then cooled to 100° C. and a stoichiometric amount of sodium hydroxide is added to neutralize the AMS and hypophosphorous acid. The reaction medium is filtered hot (100° C.) on a Beko KD3 filter to give the following results (relative % of the composition):

[0156]

[0157] The introduction of the second diol directly at the beginning is accompanied by an increase in monoesters and a higher residual fatty acid content.

[0158] Example 5: Synthesis of Isosorbide Myristate Composition (According to the Invention)

[0159] Example 1 was repeated with myristic acid replacing stearic acid (C14:0). The results are as follows:

[0160] The composition of the medium is as follows (relative % in the composition relative to the total weight of the composition):

[0161]

[0162] Example 6: Synthesis and distillation purification of isosorbide distearate (comparative example)

[0163] A comparative example was prepared in the same manner as Example 2 except that stearic acid (C18:0) was replaced with myristic acid (C14:0). The results after distillation are as follows (relative % in the composition compared to the total weight of the composition):

[0164] Diester (%) Monoester(%) Residual fatty acids (%) APHA Coloring 93 5 2 77

[0165] Example 7: (According to the present invention)

[0166] Example 2 was repeated by replacing ethylene glycol with cyclohexanedimethanol (CHDM).

[0167] The results are as follows (relative % in the composition compared to the total weight of the composition):

[0169]

[0170] Example 8 (according to the present invention) :

[0171] Example 2 was repeated by replacing ethylene glycol with neopentyl glycol (NPG). The results are as follows (relative % in the composition compared to the total weight of the composition):

[0172]

[0173] Example 9 (according to the present invention) :

[0174] Example 2 was repeated by replacing ethylene glycol with 1,4-butanediol. The results are as follows (relative % in the composition compared to the total weight of the composition):

[0175]

[0176] Example 10 (according to the present invention) :

[0177] Example 2 was repeated by replacing ethylene glycol with 1,4-benzenedimethanol. The results are as follows (relative % in the composition compared to the total weight of the composition):

[0178]

[0179] Example 11 (according to the present invention) :

[0180] Example 2 was repeated by replacing ethylene glycol with resorcinol. The results are as follows (relative % in the composition compared to the total weight of the composition):

[0181]

[0182] Example 12: Use in a process for producing polycarbonate (according to the invention)

[0183] The diester compositions of Examples 1, 3, 5 and 7 to 11 (according to the invention) have been used in a process for preparing polycarbonates.

[0184] A mixture comprising polycarbonate and about 0.5% (% by weight of the mixture) of the diester composition was extruded.

[0185] The compositions of Examples 1, 3, 5 and 7 to 11 (according to the invention) have proven to be effective in improving the melt flow of polycarbonates. By way of example: In the case of the compositions of Examples 1 and 3, the melt flow index (MFI) was determined according to ISO 1133 on a dedicated instrument (CEAST brand, model 7024). The unadded extruded polycarbonate had an MFI of 12.9 g / 10 min. The same polycarbonate with 0.5% of the composition from Example 1 added had an MFI of 43.5 g / 10 min. The same polycarbonate with 0.5% of the composition from Example 3 added had an MFI of 42.75 g / 10 min.

[0186] Furthermore, no yellowing of the final product was observed.

[0187] Example 13: Use in a method for preparing polycarbonate (Comparative Example)

[0188] The composition of C8 / C10 alkyl diesters of isosorbide sold under the name Polysorb ID46 by the applicant company has been used in the polycarbonate preparation process.

[0189] The composition of Polysorb ID46 did not improve the melt flow of the polycarbonate. It seems that due to the short alkyl chain, the diester evaporates during the molding process. For example, the extruded polycarbonate without addition has an MFI of 12.9 g / 10 min. The same polycarbonate with 0.5% of Polysorb ID46 added has an MFI of 15.7 g / 10 min.

[0190] The polycarbonate obtained after extrusion has an undesirable yellow colour.

Claims

1. A method for preparing a C13-C29 alkyl diester composition of 1,4:3,6-dianhydrohexitol, the method comprising: a) in a first step, 1,4:3,6-dianhydrohexitol is esterified with a fatty acid having a C13-C29 alkyl chain, wherein the fatty acid is in excess, to form a crude reaction product comprising a C13-C29 alkyl diester of 1,4:3,6-dianhydrohexitol and unreacted fatty acid; b) In the second step, the unreacted fatty acid is esterified with a primary diol or an aromatic diol.

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

3. The 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, pearlitic acid, tuberostearic acid, lactobacillic acid, arachidic acid, phytanic acid, succinic acid, 11-cyclohexylundecanoic acid, or a mixture thereof.

4. The method 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-decanediol, 1,12-dodecanediol, or mixtures thereof.

5. The method according to any one of claims 1 to 4, wherein the first esterification step and the second esterification step are performed in the presence of an acid catalyst.

6. A C13-C29 alkyl diester composition of 1,4:3,6-dianhydrohexitol obtainable by the method according to any one of claims 1 to 5.

7. A C13-C29 alkyl diester composition of 1,4:3,6-dianhydrohexitol, comprising, by weight of the composition: - 35 to 90% of C13-C29 alkyl diester of 1,4:3,6-dianhydrohexitol (A), - 10 to 50% of diesters of primary or aromatic diols (B), - less than 6% of C13-C29 alkyl monoesters of 1,4:3,6-dianhydrohexitol (C), - less than 3% of fatty acids with a C13-C29 alkyl chain (D), The total content of the C13-C29 alkyl diester of 1,4:3,6-dianhydrohexitol (A) and the diester of primary or aromatic diol (B) is 80 to 99%, preferably 90 to 99%.

8. The composition according to one of claims 6 or 7, wherein the 1,4:3,6-dianhydrohexitol is isosorbide.

9. The composition of any one of claims 6 to 8, wherein the alkyl diester is C13-C17 and the fatty acid has a C13-C17 alkyl chain.

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

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

12. A composition according to any one of claims 6 to 10 comprising, by weight of the composition: - 35% to 90% 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 (D).

13. The composition of any one of claims 6 to 12, having an APHA color index of less than 30.

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

Images