[0001]The invention relates to an alkoxylated polyphenols manufacturing process, specifically alkoxylated lignins.

[0002] Lignin is one of the main components of wood, cellulose and hemicellulose. Lignin is the most abundant biopolymer on Earth after cellulose. It provides the rigidity of wood cellulose interpenetrating network while providing water resistance to certain pests and wood.

[0003] Though than abundant, it is clear that the lignin is undervalued as such. So far and still today, the first valuation of the lignin is energy recovery, especially through the burning of black liquor. This valuation is important to the economic balance pulp mills. However, faced with declining production of paper pulp and the surpluses of lignins, work is conducted for a better use of it.

[0004] Thus, the interest for the use of lignin has grown over the years. An area in which the lignin properties are exploited is the strengthening of a multitude of polymers, including urethane-based polymers. In fact, the lignin can be used for the manufacture of polyurethane foams derivatives. The lignin is a polyphenol, it presents a large number of alcohol functional groups capable of reacting, for example with isocyanates to form polyurethanes derivatives. However, these alcohol functions being inaccessible in this polyphenol, it is necessary beforehand to a propoxylation reaction of these functions, leading to less congested alcohol functions (furthest from the core of the polyphenol),

[0005] Generally, the method used by various authors firstly consists of a propoxylation lignin by reacting lignin with propylene in the presence of the oxide of a catalyst then reacting the product obtained by example of the isocyanate.

[0006] Regarding the propoxylation step of lignin, the authors usually operate in autoclaves or Parr bombs. All of the lignin, such as lignin kraft type, is charged with propylene oxide and a basic catalyst in suitable proportions under nitrogen. The reactor was then closed and heated.

[0007] The reaction is initiated around 150 ° C with a strong exotherm which causes

a sudden rise in temperature to 250 ° C and pressure of a few bars to more than 20 bar. The authors believe that the reaction is complete when the pressure and temperature decrease and reach a stable level.

[0008] Given the strong exothermic reaction, authors must ensure strict monitoring and control of the reaction conditions for safety reasons. The process widely used is not transposable industrially.

[0009] According to the thesis entitled "Lignin-based Polyurethanes: Characterization, Synthesis and Applications" Borges Cateto, (2008), lignin, propylene oxide and a catalyst are introduced into a reactor which is closed and which is then heated to 160 ° C. The pressure and temperature increase to a maximum that depends on a number of parameters. Propoxylated lignin is recovered at the end of reaction. It is stated in this document that the reaction was carried out on samples of 100 g.

[0010] Furthermore, since the conditions of temperature, pressure and the residual presence of water, a part of propylene oxide can be homopolymerized, as mentioned in the document EP2816052. Propoxylated lignin is then mixed with poly (propylene) glycols, which can not be separated easily from the propoxylated lignin.

[0011] That being said, some authors have managed to overcome the control of the exothermic problem as mentioned above. Indeed, the document WO2015 / 083092 discloses a method in which a solid dispersion of lignin is carried out in a polyethylene glycol dispersant, di or tetraethylene glycol or propoxylated glycerol followed by addition of a base. Then, propylene oxide is added continuously.

[0012] However, the product produced is a blend of propoxylated lignin dispersant and optionally propoxylated, difficult to separate from the propoxylated lignin. It is also noteworthy that the reaction times are extremely long, the temperature during the reaction is low and the pressure used in the reaction is low.

[0013] Similarly, document US2015 / 0038665 discloses a method in which propylene oxide is added continuously to a mixture consisting of lignin, glycerol, the polyol lignin and a catalyst. However, this method has the great disadvantage of leaving in the finished product a lignin mixture with propoxylated glycerol or propoxylated glycerol.

[0014] Furthermore, it is noted that the lignin is in solid form. Therefore, it is difficult to induce in the form of a homogeneous reaction medium. She, moreover, tend to generate deposits that can clog the various components of a facility, such as reactors, piping, valves, pipes, etc .. For this reason, it is difficult to handle the industrially. [0015] The above references disclose suspended in lignin dispersants, which can dissolve at least partially or lignin. However, these methods require further separation steps to isolate the propoxylated lignin reaction byproducts of the dispersant with the reactants. Furthermore,

[0016] Thus, there is sought an industrial process alkoxylation, in particular propoxylation, polyphenols, such as lignin, allowing sufficient solubilization and leading to a product directly usable, that is to say which can be used directly in the next step without an intermediate separation step is necessary.

[0017] The present invention is to propose a solution to solve all the above problems.

[0018] Thus, the present invention relates to a method for producing at least one alkoxylated polyphenol comprising the following successive steps:

(A) reacting at least one polyphenol, at least one alkoxylating agent, at least one catalyst in the presence of at least one poly (oxyalkylene glycol) as a solvent at a temperature ranging from 80 ° C to 200 ° C, preferably 100 ° C to 170 ° C, under a pressure ranging from 0.15 to 2 MPa, preferably 0.2 MPa to 1, 8 MPa; then

(B) remove residual alkoxylating agent.

[0019] The method of the invention allows to synthesize the alkoxylated polyphenol in safe conditions, so that it can be carried out on an industrial scale. Indeed, the operating conditions in terms of temperature and pressure are controlled by the method according to the invention. The exothermic reaction is controlled in particular. In addition, the method of the invention provides an alkoxylated polyphenol with a good yield and in reaction times quite reasonable, consistent with industrial use.

[0020] Moreover, the alkoxylated polyphenol obtained by the process according to the invention can be used crude without purification. The method of the invention also has the advantage of not restrict the use of alkoxylating agent only propylene oxide. Ethylene oxide and / or butylene oxide or mixtures thereof may for example be also used.

[0021] It is specified that the expressions "from ... to ..." used herein shall be construed as including each of the mentioned limits. Throughout the text, the pressures are expressed in megapascals (MPa) absolute.

[0022] Step (a): The process according to the invention comprises a step (a) reacting at

least one polyphenol, at least one alkoxylating agent, at least one catalyst in the presence of at least one poly (oxyalkylene glycol) as a solvent at a temperature ranging from 80 ° C to 200 ° C, preferably 100 ° C at 170 ° C under a pressure ranging from 0.15 MPa to 2 MPa, preferably 0.2 MPa to 1, 8 MPa.

[0023] Polyphenols: The polyphenols used in the method according to the invention may be selected from tannins, lignins and various natural polyphenols tannins and lignins. Advantageously, said polyphenol is a lignin, preferably selected from kraft lignin, lignosulfonates and lignin organosolv kind.

[0024] The Kraft lignin is derived from the papermaking process of the same name. Regarding the chemical structure, the kraft lignin is a combination of three phenolic compounds, coumaryl alcohol, coniferyl alcohol and sinapyl alcohol. As an example of kraft lignin can be used among other Nndulin AT ™ sold by the company Ingevity, kraft lignin Fibria sold by the company, or lignin marketed by Stora Enso.

[0025] The lignosulfonates differ structurally from kraft lignin by adding sulfonic functions generally salified, which ensures their better solubility in water. Examples of lignosulfonates are Borresperse ™ type lignosulfonates Ultrazine ™, Ufoxane ™ or Vanisperse ™.

[0026] The type of organosolv lignins are obtained by chemical attack of woody plants, such as cereal straw, using various solvents, such as formic acid or acetic acid. Among the various sources of lignins organosolv kind, there is the Biolignin ™ marketed by the company CIMV or sold by the company Fibria.

[0027] Preferably, the polyphenol used is lignin.

[0028] The alkoxylating agents: The alkoxylating agents used in the method according to the invention may be selected from those of formula (I):

wherein Ri denotes a hydrogen atom or an alkyl radical C1-C6.

[0029] Preferably, Ri denotes a hydrogen atom or an alkyl radical in C1-C2. Thus, the alkoxylating agent is preferably selected from ethylene oxide, propylene oxide, butylene oxide, and mixtures thereof, preferably propylene oxide.

[0030] Preferably, the mass ratio polyphenol / alkoxylating agent is from 0.05 to 2,

preferably from 0.1 to 1, more preferably from 0.15 to 0.9, even more preferably from 0.15 to 0.7.

[0031] Catalyst: The catalyst used in the process according to the invention may be selected from alkali metal hydroxides, sodium or potassium alcoholates, and tertiary amines chosen from trialkylamines and tetramethylguanidine, preferably selected from alkali metal hydroxides.

[0032] More preferably, the catalyst used in the process according to the invention can be chosen from lithium hydroxide, sodium hydroxide, potassium hydroxide and cesium hydroxide.

[0033] Advantageously, the catalyst represents 0.01% to 10% by weight, preferably from 1% to 6% by weight relative to the weight of polyphenol.

[0034] Poly (oxyalkylèneglvcol): Advantageously, said poly (oxyalkylene glycol) is selected from polypropylene glycol, polybutylene glycol, block copolymers, alternating or statistics obtained from these monomers, and mixtures thereof. The alkoxylated polyhydric phenol obtained by using this poly (oxyalkylene) is preferably a specific liquid and homogenous.

[0035] Preferably, the poly (oxyalkylene) used in the method according to the invention is selected from dipropylene glycol, tripropylene glycol, tetrapropylene glycol, polypropylene glycol 220, polypropylene glycol 400 and the mixture thereof, more preferably selected from polypropylene glycol 220, polypropylene glycol 400 and mixtures thereof.

[0036] Preferably, the molar mass of the poly (oxyalkylene) is greater than or equal to 100 g. mol "1 , more particularly from 100 g. mol " 1 to 6000 g. mol "1 , and even more preferably from 150 g. mol " 1 to 2000 g. mol "1 .

[0037] According to a particular embodiment of the invention, the mass ratio polyphenol / poly (oxyalkylene) is less than or equal to 2, preferably less than or equal to 1, more preferably less than or equal to 0.5.

[0038] Preferably, the mass ratio polyphenol / poly (oxyalkylene) is greater than or equal to 0.05. Advantageously, the mass ratio polyphenol / poly (oxyalkylene) is from 0.05 to 0.5. According to a preferred embodiment of the method according to the invention, the poly (oxyalkylene) is the only solvent in the reaction medium of step (a).

[0039] Reaction Conditions: Step (a) according to the invention is carried out at a temperature ranging from 80 ° C to 200 ° C, preferably 100 ° C to 170 ° C. The reaction pressure is from 0.15 MPa to 2 MPa, preferably 0.2 MPa to 1, 8 MPa, more preferably from 0.2 MPa to 0.6 MPa.

[0040] Preferably, the duration of step (a) varies from a few minutes to several hours, preferably 5 minutes to 72 hours, more preferably from 10 minutes to 24 hours, more preferably from 10 minutes to 12 hours.

[0041] Step (b): As indicated above, the method according to the invention comprises a step (b) removal of residual alkoxylating agent. meaning the means of the present invention by "residual alkoxylating agent" an alkoxylating agent which has not reacted.

[0042] Preferably, said removing residual alkoxylating agent step is carried out by cooking, that is to say, by maintaining the temperature from 70 ° C to 170 ° C, preferably 70 ° C to 130 ° C to consume residual alkoxylating agent, and / or a stripping step under an inert gas stream. Alternatively, said stripping step can be performed by steam or under vacuum.

[0043] Preferably, after said step (b), the mass content of residual alkoxylating agent is less than or equal to 1% by weight of alkoxylated polyphenols obtained at the end of step (b), preferably less than or equal to 0.1%, more preferably less than or equal to 0.01%.

[0044] The alkoxylated polyphenol obtained is in the form of a viscous liquid of a dark color.

[0045] The crude product is directly used as it is for the manufacture of derivatives of polyurethane foams (PU) rigid thermal insulation for example. For other applications, it can be eliminated by methods known to the skilled artisan, traces of catalyst.

[0046] Preferably, the method according to the invention comprises the following successive steps:

(A1) mixing in a reactor at least one polyphenol, at least one poly (oxyalkylene glycol) as solvent according to the pre-mentioned proportions, and at least one catalyst;

(A2) optionally drying the mixture;

(A3) adding to the mixture at least one alkoxylating agent.

[0047] Advantageously, step (a) is conducted at a temperature ranging from 80 ° C to 200 ° C, preferably from 100 ° C to 170 ° C under a pressure ranging from 0.15 MPa to 2 MPa, preferably 0.2 MPa to 1, 8 MPa.

[0048] Preferably, the optional step (b) drying the mixture is carried out by stripping with nitrogen or steam.

[0049] Moreover, the method may be implemented in batch, semi-continuously or continuously.

[0050] According to a first variant of the process according to the invention, the method according

the invention is of batch type or semi-continuous. In this variant, step (a) can be decomposed into the following 3 successive steps:

(A1) mixing in a reactor at least one polyphenol, at least one poly (oxyalkylene glycol) as solvent according to the pre-mentioned proportions, and at least one catalyst, at a temperature ranging from 80 to 200 ° C, preferably 100 to 170 ° C, under a pressure ranging from 0.15 to 2 MPa, preferably from 0.2 to 1, 8 MPa;

(A2) optionally drying the mixture;

(A3) adding to the mixture in at least one step in semi-continuously at least one alkoxylating agent.

[0051] The step (a2) optionally comprises removing any water formed during the reaction of the catalyst on the polyphenol or feed by the catalyst in aqueous solution. This drying step (a2) may be effected by hot nitrogen stripping, that is to say at a temperature ranging from 50 ° C to 130 ° C and optionally under reduced pressure between 0.002 MPa and 0.1 MPa.

[0052] In step (a3), the reactor is purged with nitrogen. Is pressurized to a pressure ranging from 0.15 MPa to 0.4 MPa, and the reaction medium is heated under stirring at a temperature ranging from 100 ° C to 150 ° C.

[0053] then introduced semi-continuously the alkoxylating agent or mixture of alkoxylating agents to a feed rate to control the temperature and the safety pressure. The reaction is carried out at a temperature ranging from 80 ° C to 200 ° C with a preference of 100 ° C to 170 ° C. The pressure varies depending on the reactor type and degree of filling of the latter and ranges from 0.15 MPa to 2 MPa.

[0054] At the end of reaction, is carried out in step (b) removal of residual alkoxylating agent which is to consume the rest of alkoxylating agent by maintaining the temperature. There is a drop in pressure until the theoretical pressure caused by nitrogen alone. One can also perform a stripping step with an inert gas such as nitrogen, or steam and / or vacuum to remove the last traces of alkoxylating agent.

[0055] A second variant of the process according to the invention is a continuous-type process, comprising the following successive steps:

(A1) mixing in a reactor at least one polyphenol, at least one poly (oxyalkylene glycol) as solvent according to the pre-mentioned proportions, and at least one catalyst, at a temperature ranging from 80 to 200 ° C, preferably 100 to 170 ° C, under a pressure ranging from 0.15 to 2 MPa, preferably from 0.2 to 1, 8 MPa, said polyphenol, said poly (oxyalkylene) and said catalyst is added continuously,

(A2) optionally drying the mixture;

(A3) adding at least one step of continuously at least one alkoxylating agent, the reaction medium being continuously withdrawn.

[0056] The step (a1) is carried out by feeding the polyphenol, poly (oxyalkylene), and catalyst in a reactor. The reactor may be a stirred tank or a mixing device such as an extruder. This step can be carried out continuously with continuous supply of reactants and continuous take off from the reaction mixture formed.

[0057] It can also be carried out in batch with a sequential feeding of the reagents, and then a mixing step and a drying step as described in the first embodiment. The reaction product can then be continuously fed to step (a3).

[0058] In step (a3), the reaction mixture from step (a1) or optionally of step (a2) and at least one alkoxylating agent are added continuously in a reactor system, which may consist a continuous stirred tank or a cascade of continuous stirred tanks or an extruder. The crude alkoxylated polyphenol is continuously withdrawn from the reactor system.

[0059] Preferably, the step (a3) ​​comprises a cascade February to June continuous stirred tanks. The first tank is continuously supplied with the reaction mixture from step (a1) or step (a2) and each subsequent tank is fed continuously by the flow drawn off from the preceding tank.

[0060] Advantageously, each continuous stirred tank is continuously supplied with a portion of the alkoxylating agent stream to obtain a narrower polydispersity polyphenol alkoxylated product.

[0061] Preferably, the method according to the invention comprises a step (c) recovering the alkoxylated polyphenol obtained at the end of step (b).

[0062] The present invention also relates to an alkoxylated polyphenol obtainable by the process according to the invention.

[0063] The invention also relates to the use of poly (oxyalkylene glycol) as a solvent in a alkoxylated polyphenols manufacturing method, in particular such as that defined above.

[0064] The present invention finally has for alkoxylated polyphenol using object obtained by the method according to the invention for making polyurethanes, polyesters, nonionic or cationic, biobased precursor of carbon fiber.

[0065] The present invention is further illustrated by the following nonlimiting examples.

EXAMPLES

Example 1 (according to invention): Synthesis propoxylated lignin in the presence of PPG 220

[0066] In an autoclave of 6 L, 208.4 g of lignin Indulin AT ™ were charged, previously dried in an oven, in 479.3 g of polypropylene glycol 220 (PPG 220) and 8.3 g of cesium hydroxide finely ground. The mass ratio lignin / PPG 220 was 43.5 wt% and the mass ratio catalyst / lignin is 4% by weight.

[0067] The procedure to 3 successive purges with nitrogen. We also conduct leak tests. Is progressively increased temperature with stirring of the reaction medium to 80 ° C. It returns under nitrogen pressure to 0.25 MPa, and then introducing a fraction of 50 g of propylene oxide. The temperature rose gradually to a temperature of 120 ° C, at which temperature one can see the attachment of the reaction.

[0068] We introduce the whole of the propylene oxide, 488 g at a temperature of from 120 ° C to 130 ° C at a maximum pressure of 0.6 MPa and at an average throughput of 140 g. h "1 . The temperature was maintained at 130 ° C until a pressure stage. After the addition, the mixture is stirred for one hour so that all of the propylene oxide is consumed, then the residual stripped with nitrogen for 1 hour at 80 ° C.

[0069] is recovered 1125 g of product as a dark viscous liquid. The product is homogeneous and does not contain unreacted lignin bean. Its hydroxyl number (OHN) is 290 mg KOH.g "1 .

Example 2 (according to invention): Synthesis propoxylated lignin in the presence of PPG 400

[0070] In a 6 L autoclave was charged with 215 g of lignin Indulin AT ™, previously dried in an oven, 500 g of polypropylene glycol 400 (PPG 400) and 8.6 g of finely ground cesium hydroxide. The mass ratio lignin / PPG 400 is 43 wt% and the mass ratio catalyst / lignin is 4% by weight.

[0071] The procedure to 3 successive purges with nitrogen. We also conduct leak tests. Is progressively increased temperature with stirring of the reaction medium to 80 ° C. It returns under nitrogen pressure to 0.25 MPa is then introduced a fraction of 50 g of propylene oxide. The temperature rose gradually to a temperature of 130 ° C, at which temperature one can see the attachment of the reaction.

[0072] We introduce the totality of propylene oxide, 500 g, at a temperature ranging from 130 ° C to 140 ° C and a maximum pressure of 0.6 MPa at an average rate of 85 g. h "1 . The temperature was maintained at 130 ° C until a pressure level. At the end

addition, the mixture is stirred for one hour so that all of the propylene oxide is consumed and then the residual stripped with nitrogen for 1 hour at 80 ° C.

[0073] is recovered 1100 g of product as a dark viscous liquid. The product is homogeneous and does not contain unreacted lignin bean. Its hydroxyl number (OHN) is 202 mg KOH.g "1 .

CLAIMS

1. A method of manufacturing at least one alkoxylated polyphenol comprising the following successive steps:

(A) reacting at least one polyphenol, at least one alkoxylating agent, at least one catalyst in the presence of at least one poly (oxyalkylene glycol) as a solvent at a temperature ranging from 80 ° C to 200 ° C, preferably 100 ° C to 170 ° C under a pressure ranging from 0.15 MPa to 2 MPa, preferably 0.2 MPa to 1, 8 MPa; then

(B) remove residual alkoxylating agent.

2. The method of claim 1, wherein said polyphenol is selected from tannins, lignins and various natural polyphenols tannins and lignins, preferably lignins.

3. The method of claim 2, wherein said polyphenol is a lignin, preferably selected from kraft lignin, lignosulfonates and lignin organosolv kind.

4. A method according to any preceding claim, wherein said alkoxylating agent is of formula (I):

wherein Ri denotes a hydrogen atom or an alkyl radical C1-C6.

5. A method according to any preceding claim, wherein said alkoxylating agent is selected from ethylene oxide, propylene oxide, butylene oxide, and mixtures thereof.

6. A method according to any preceding claim, wherein the mass ratio polyphenol / alkoxylating agent is from 0.05 to 2, preferably from 0.1 to 1, more preferably from 0.15 to 0.9, even more preferably from 0.15 to 0.7.

7. A method according to any preceding claim, wherein the catalyst is selected from alkali metal hydroxides, sodium or potassium alcoholates, and tertiary amines chosen from trialkylamines and tetramethylguanidine, preferably selected from alkali metal hydroxides.

8. A method according to any preceding claim, wherein said poly (oxyalkylene glycol) is selected from polypropylene glycol, polybutylene glycol, block copolymers, alternating or statistics obtained from these monomers, and mixtures thereof.

9. A method according to any preceding claim, wherein said said poly (oxyalkylene glycol) is selected from dipropylene glycol, tripropylene glycol, tetrapropylene glycol, polypropylene glycol 220, polypropylene glycol 400 and the mixtures thereof, preferably selected from polypropylene glycol 220, polypropylene glycol 400 and mixtures thereof.

10. A method according to any preceding claim, wherein the mass ratio polyphenol / poly (oxyalkylene) is less than or equal to 2, preferably less than or equal to 1, more preferably less than or equal to 0.5.

11. A method according to any preceding claim, wherein it is carried out batchwise, semi-continuously or continuously.

12. A method according to any preceding claim, comprising a step (c) recovering the alkoxylated polyphenol obtained at the end of step (b).

13. Polyphenol alkoxylated obtainable by the process as defined in any one of the preceding claims.

14. Use of poly (oxyalkylene glycol) as a solvent in a alkoxylated polyphenols manufacturing process.

15. Use of alkoxylated polyphenol obtained by the process as defined in any one of claims 1 to 12 for the manufacture of polyurethanes, polyesters, nonionic or cationic surfactants, bio-based carbon fiber precursors.