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 pulp and lignin surpluses, 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 causes a sharp temperature rise 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, which 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 dispersing agent, such as polyethylene glycol, di- or tetra-ethylene 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.

[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 also difficult to handle 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.

[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] The invention relates to a method for 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 alkoxylated polyhydric phenol as a solvent, the mass ratio polyphenol / polyphenol alkoxylated as solvent is less than 2 , preferably less than or equal to 1, 5, more preferably less than or equal to 1, even more preferably less than or equal to 0.5; and

(B) remove residual alkoxylating agent.

[0019] The method of the invention uses as reaction solvent, in particular polyphenol, the polyphenol alkoxylated. Depending on the amount of solvent used, the reaction medium is heterogeneous or homogeneous, most generally heterogeneous. The alkoxylated polyhydric phenol as solvent serves to solubilize at least partially the polyphenol and disperse part of polyphenol which is not solubilized. Therefore, this specific choice of solvent solves the problems associated with separation of the resulting alkoxylated polyphenol. alkoxylated polyphenol obtained by the process according to the invention can be used crude without further purification as the elimination of the alkoxylating agent unreacted, and neutralization of the catalyst.

[0020] Moreover, the method according to the invention has the advantage 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 exotherm of the reaction is controlled in particular by the presence of a solubilising solvent partly polyphenol and diluting the alkoxylating agent.

[0021] Finally, the method according to the invention also has the advantage not to restrict the use of alkoxylating agent only propylene oxide. Ethylene oxide and / or butylene oxide or mixtures thereof may also be used.

[0022] 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.

[0023] 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 alkoxylated polyphenol as solvent, the mass ratio polyphenol / polyphenol alkoxylated as solvent is less than 2, preferably less than or equal to 1, 5, more preferably less than or equal to 1, even more preferably less than or equal to 0.5.

[0024] Polyphenols: The polyphenols used in the method according to the invention may be selected from tannins, lignins and various natural polyphenols tannins and lignins, preferably lignins. Advantageously, said polyphenol is a lignin, preferably selected from kraft lignin, lignosulfonates and lignin organosolv kind.

[0025] 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.

[0026] 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 ™.

[0027] 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. Preferably, the polyphenol used is lignin.

[0028] The alkoxylating agents: The alkoxylating agents used in the method according to the invention may be chosen 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, more preferably 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] Polyphenol alkoxylated: The alkoxylated polyhydric phenol used as the reaction solvent used in the method according to the invention is a solvent of the reagent, the polyphenol. In this sense, it dissolves at least a portion of the polyphenol. The alkoxylated polyhydric phenol obtained at the end of step (a) is the reaction product of a polyphenol and an alkoxylating agent.

[0035] Advantageously, the alkoxylated polyhydric phenol as the solvent and the alkoxylated polyphenol manufactured by the method according to the invention are identical or different, preferably identical.

[0036] Preferably, said alkoxylated polyhydric phenol as the solvent used in step (a) is obtained by reacting the polyphenol with the same alkoxylating agent as used in step (a). The latter may be chosen from ethylene oxide, propylene oxide, butylene oxide and mixtures thereof, in the presence of at least one catalyst.

[0037] Advantageously, said alkoxylated polyhydric phenol as the solvent is obtained by the process according to the invention. When the reaction is carried out in batch, part of polyphenol alkoxylated product during an operation can be reused for the operation

next. When the reaction is carried out continuously, part of the alkoxylated product polyphenol can be used as solvent for the reaction, which occurs in the alkoxylated polyphenol.

[0038] The first operation in batch or the start of the continuous reaction may use an alkoxylated polyhydric phenol as the solvent product according to another procedure of the invention. It can be obtained by any method known in the art, such as that described in the thesis entitled "Lignin-Based Polyurethanes: Characterization, Synthesis and Applications" Borges Cateto, (2008).

[0039] The mass ratio polyphenol / polyphenol alkoxylated as solvent is less than 2, preferably less than or equal to 1, 5, more preferably less than or equal to 1, even more preferably less than or equal to 0.5. Preferably, the mass ratio polyphenol / polyphenol alkoxylated as a solvent is greater than or equal to 0.05.

[0040] Advantageously, the mass ratio polyphenol / polyphenol alkoxylated as solvent is from 0.05 to 0.5, preferably from 0.1 to 0.4, and more preferably 0.1 to 0.3. Said mass ratio corresponds to the contents of the reactants.

[0041] According to a preferred embodiment of the method according to the invention, the alkoxylated polyhydric phenol as the solvent is the sole solvent of the reaction medium of step (a), that is to say that the solvent consists of alkoxylated polyphenol.

[0042] Reaction Conditions: Step (a) according to the invention can be carried out at a temperature ranging from 70 ° C to 200 ° C, preferably 70 ° C to 170 ° C, more preferably 100 ° C at 170 ° C. The reaction pressure may range from 0.1 MPa to 1, 8 MPa, and preferably from 0.1 MPa to 0.6 MPa.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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%.

[0047] The alkoxylated polyphenol obtained is in the form of a viscous liquid of a dark color. The crude product was directly used as such 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.

[0048] Preferably, the method according to the invention comprises the following successive steps:

(A1) mixing in a reactor at least one polyphenol, at least one alkoxylated polyhydric phenol as the 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.

[0049] Preferably, the optional step (b) drying the mixture is carried out by stripping with nitrogen or steam.

[0050] Moreover, the method may be implemented in batch, semi-continuously or continuously.

[0051] According to a first variant of the process according to the invention, the method according to the invention 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 alkoxylated polyhydric phenol as the solvent according to the pre-mentioned proportions, and at least one catalyst; (A2) optionally drying the mixture;

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

[0052] 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 0.001 MPa and 0.1 MPa.

[0053] In step (a3), the reactor is purged with nitrogen. Is pressurized to a pressure ranging from 0.05 to 0.4 MPa, and the reaction medium is heated under stirring at a temperature ranging from 100 to 160 ° C.

[0054] 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 generally carried out at a temperature ranging from 70 ° 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 varies from 0.1 to 1, 8 MPa.

[0055] 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.

[0056] A second variant of the process according to the invention is a continuous-type process, comprising the following successive steps:

(A1) Mix in a reactor at least one polyphenol, at least one alkoxylated polyhydric phenol as the solvent according to the pre-mentioned proportions, and at least one catalyst, said polyphenol, said alkoxylated polyhydric phenol as solvent and said catalyst being added in continued,

(A2) Optionally drying the mixture;

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

[0057] The step (a1) is carried out by feeding the polyphenol, the polyphenol alkoxylated as solvent and catalyst in a reactor. The reactor may be a stirred tank or a mixing device such as an extruder. It is operated at a temperature of 70 ° C to 200 ° C. The pressure may range from 0.001 MPa to 0.4 MPa, and preferably 0.001 MPa to 0.1 MPa. This step can be carried out continuously with continuous supply of reactants and continuous take off from the reaction mixture formed.

[0058] 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).

[0059] 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.

[0060] 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.

[0061] Advantageously, each continuous stirred tank is continuously supplied with a portion of the alkoxylating agent stream to obtain a narrower polydispersity polyphenol alkoxylated product.

[0062] In the reaction system, the temperature can be maintained from 80 to 200 ° C, and preferably 100 to 170 ° C and more preferably from 130 to 170 ° C. The pressure is generally between 0.1 and 1, 8 MPa.

[0063] When starting the installation, the reactor of step (a1) and the step of reactor system (a2) can be filled at least partially with at least one alkoxylated polyphenol.

[0064] The alkoxylated polyphenol obtained by the process according to the invention can be used as solvent in an alkoxylated polyphenols manufacturing method, in particular such as that defined above.

[0065] Preferably, the method according to the invention comprises a step (c) recovering the alkoxylated polyphenol obtained at the end of step (b).

[0066] The present invention also relates to an alkoxylated polyphenol obtainable by the process according to the invention.

[0067] 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.

[0068] The present invention is further illustrated by the following nonlimiting examples.

EXAMPLES

Example 1: Synthesis of a lignin propoxylated according to the invention

[0069] In a 6 L autoclave was charged with 500.4 g of propoxylated lignin obtained by the process described in the pre-cited thesis whose operation is specified on pages 97 and 98 (see Table 4.8 Indulin AT ™, formulation 30/70/2 p. 122), said process being repeated several times, and 144.8 g of lignin Indulin AT ™, predried.

[0070] The mass ratio of lignin / propoxylated lignin is 0.29 by weight and the weight ratio catalyst / lignin is 4.5% 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 up to 1 10 ° C. Is carried to a stripping nitrogen at this temperature and under 0.02 MPa to dry the medium for 1 hour. It returns under nitrogen pressure to 0.286 MPa is then introduced a fraction of 45 g of propylene oxide. The temperature is increased at a temperature ranging from 140 ° C to 150 ° C. At 145 ° C, there is the attachment of the reaction. Is introduced all propylene oxide or 830 g at a temperature of 150 ° C and a maximum pressure of 0.55 MPa, at an average rate of 200 g / h. The temperature was maintained at 150 ° C until a pressure bearing. At the end of 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 100 ° C. Is recovered 1455 g of product as a dark viscous liquid. The product is homogeneous and does not contain unreacted lignin bean. Its hydroxyl number (OHN) is 160 mg KOH / g.

example 2

[0072] 5 is carried out successive batches according to the protocol described in Example 1. Propoxylated lignin used in the first batch is the product obtained in Example 1. A portion of each batch is propoxylated lignin following batch.

[0073] It is noted that the product of each batch is a homogeneous dark viscous liquid which does not contain unreacted lignin grain.

CLAIMS

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 alkoxylated polyhydric phenol as a solvent, the mass ratio polyphenol / polyphenol alkoxylated as solvent is less than 2 , preferably less than or equal to 1, 5, more preferably less than or equal to 1, even more preferably less than or equal to 0.5; 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.

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 the mass ratio polyphenol / polyphenol alkoxylated as solvent is from 0.05 to 0.5, preferably from 0.1 to 0.4, and more preferably 0 1 to 0.3.

9. A method according to any preceding claim, wherein the temperature in step (a) is from 70 ° C to 200 ° C, preferably from 70 to 170 ° C, more preferably 100 to 170 ° C .

10. A method according to any preceding claim, wherein the pressure during step (a) is from 0.1 to 1, 8 MPa, and preferably from 0.1 to 0.6 MPa.

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 alkoxylated polyphenol obtained by the process as defined in any one of claims 1 to 12 as a solvent in an 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, non-ionic surfactants, nonionic surfactants or cationic biobased precursors of carbon fiber .