Lignin monomer-derived thermoplastic polyurethane

Abstract

This invention provides a method for synthesizing thermoplastic polyurethane. [Solution] The present invention provides a method for synthesizing thermoplastic polyurethanes containing lignin-derived monomers, lignin-type compounds, or products obtained by the functionalization of each thereof in their structure. More specifically, the process relates to the use of 4-hydroxylalkylphenols and their derivatives as lignin-derived monomers or lignin-type compounds. These can act as chain extenders or become part of a polyol. The thermoplastic polyurethanes can be partially or completely bio-based.

Description

[Technical Field]

[0001] This invention generally relates to thermoplastic polyurethanes containing lignin-derived monomers, lignin-type compounds, or products obtained by the functionalization of each thereof in their structure. More specifically, this process relates to the use of 4-hydroxylalkylphenols and their derivatives as lignin-derived monomers or lignin-type compounds. These can act as chain extenders or become part of a polyol. Thermoplastic polyurethanes can be partially or completely bio-based. Furthermore, this invention relates to methods for preparing these thermoplastic polyurethanes and their uses. [Background technology]

[0002] Polyurethanes are polymers widely used, particularly in applications such as coatings, molded articles, foams (rigid and flexible), sealants, and synthetic fibers. Current synthetic polyurethanes are the result of reactions between diisocyanate monomers or high molecular weight isocyanate monomers and hydroxyl group-containing monomers (diols, triols, or polyols).

[0003] Lignin is the second largest biopolymer on Earth after cellulose, but unlike the latter, lignin is currently undervalued. Due to its high content of hydroxyl groups (both aliphatic and aromatic), lignin is being sought as a polyol substitute in polyurethane synthesis (Non-Patent Document 1). However, lignin derived from the isolation of cellulose, also known as industrial lignin, has a high molecular weight and polydispersity due to condensation that occurs under the harsh reaction conditions of cellulose isolation. As a result, these types of lignin typically yield poor-performing polymers. Depolymerization or fractionation of lignin can yield low molecular weight oligomers with increased hydroxyl functional value, resulting in polyurethane polymers with improved properties. This concept has been demonstrated in several scientific papers (Non-Patent Document 2), and patent documents also exist (Patent Document 1). As shown in Patent Documents 2 and 3, depolymerized lignin can also be chemically modified before polyurethane synthesis.

[0004] Despite the advantages of depolymerized lignin over non-depolymerized lignin, most depolymerization protocols still use high temperatures and acidic / basic media, resulting in low monomer yields. In fact, using lignin-derived monomers in polyurethane synthesis is an ideal scenario because it allows for defined structures and provides a temporary substitute for petroleum-derived monomers. Several lignin-type compounds, such as dimerized ferulic acid (Non-Patent Literature 3) or dimerized cresol (Non-Patent Literature 4), have been used in polyurethane synthesis.

[0005] A novel technique has recently been developed that enables the isolation of monomers from lignin in good yield and selectivity, based on mild fractionation and / or depolymerization conditions and strategies for stabilizing intermediates formed during depolymerization (Non-Patent Documents 5 and 6). These monomers can be divided into two major categories based on the terminal groups on the alkyl chain: 4-alkylphenols and 4-hydroxyalkylphenols. This patent relates to the use of 4-hydroxyalkylphenol (formula Ia) and its derivatives (formula Ib) for polyurethane synthesis. [ka] Equation Ia (In the formula, R 1 and R 2 represents H or CH3 independently, R 3 and R 4 This independently represents H or OCH3, n is between 0 and 3.

[0006] The use of these monomers enables bio-based molecules to serve as diol alternatives, thus bringing new possibilities to polyurethane synthesis. Lignin-derived diols can be used as part of a chain extender and / or polyol. By using lignin-derived monomers as diols, (partially) bio-based thermoplastic polyurethanes (hereinafter referred to as TPU) can be produced. In contrast to standard polyurethanes, TPU typically consists of linear segmented block copolymers in which hard segments and soft segments are alternately arranged. The hard segments are the result of the reaction of diisocyanates with short-chain diols, so-called chain extenders in the art, and the soft segments are composed of long-chain diols, so-called polyols in the art. In this patent, both lignin-derived 4-hydroxyalkylphenol molecules of formula I and petroleum-derived 4-hydroxyalkylphenol-type compounds (both of which are collectively referred to as lignin-derived 4-hydroxyalkylphenol monomers and represented by formula I) are used as short-chain diols, i.e., as chain extenders for forming TPU, or as part of the soft phase. Since TPU needs to have a straight chain, monomers having two hydroxyl groups, i.e., diols, are required. As a result, the use of lignin in polymeric form or oligomers derived from its depolymerization is not suitable. Although thermoplastic behavior has been reported for TPU formed from partially acetylated lignin (Non-Patent Document 7), in the case of polymeric lignin, the hydroxyl value, and thus the properties of the resulting polymer, cannot be accurately controlled.

[0007] TPU typically exhibits high elasticity, along with high mechanical strength, high impact properties, high abrasion resistance, low-temperature performance, and oil resistance. Due to these properties, TPU is suitable for a wide range of applications, such as sports goods, medical devices, mobile electronic devices, laptop keyboard protectors, automotive instrument panels, caster wheels, power tools, footwear, performance films, wire and cable jackets, adhesive and fabric coating applications, and 3D printing, etc. Novel, fully or partially bio-based TPU can be used in the applications listed above.

[0008] There is no prior art regarding the use of the structure of Formula I for polyurethane synthesis, nor is there prior art regarding the functionalization of that structure for subsequent polyurethane synthesis. There are examples of the functionalization of similar structures (4-hydroxylalkylphenols), but the purpose is not to make them into polymeric monomers. There are several reports on functionalizing phenolic hydroxyls to anchor aliphatic hydroxyls to form dialiphatic diols. Patent Document 4 has an example of synthesizing 4-(3-hydroxypropoxy)benzeneethanol by reacting 2-(4-hydroxyphenyl)ethanol with ethylene carbonate or 3-chloro-1-propanol. In a scientific paper (Non-Patent Document 8), 4-hydroxybenzene methanol is reacted with 3-bromo-1-propanol to produce 4-(3-hydroxypropoxy)benzene methanol. In a scientific paper (Non-Patent Document 9), 4-(3-hydroxypropyl)-2-methoxyphenol is reacted with ethylene oxide to obtain 3-(4-(2-hydroxyethoxy)-3-methoxyphenyl)propan-1-ol.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

[0010] [Non-Patent Document 1] Rev. Adv. Mat. Sci. 2015, 40, 146-154 [Non-Patent Document 2] Top Curr Chem, 2018, 373: 32 [Non-Patent Document 3] Eur. Polym. J. 2015, 63, 186-193 [Non-Patent Document 4] Green Chem. 2015, 17, 4546-4551 [Non-Patent Document 5] Chem. Rev. 2018 118, 614 [Non-Patent Document 6] Chem. Soc. Rev. 2018, 47, 852 [Non-Patent Document 7] Fibers and Polymers, 2013, 14, 1082-1093 [Non-Patent Document 8] Synthesis 2001, 382-388 [Non-Patent Document 9] Appita 1982, 3, 192-196 [Overview of the project]

[0011] Therefore, the present invention aims to provide the use of a lignin-derived 4-hydroxyalkylphenol monomer, which can be represented by formula I, as a diol in the synthesis of thermoplastic polyurethane (TPU). [ka] Equation I (In the formula, R 1 and R 2 each independently represents H or alkyl, especially H or C 1-6 alkyl, more particularly H or CH3, R 3 and R 4 each independently represents H or oxyalkyl, especially H or oxyC 1-6 alkyl, more particularly H or OCH3, R 5 is H or hydroxyalkyl, especially H or hydroxyC 1-12 alkyl, n is 0 to 3)

[0012] By the depolymerization of lignin, the 4-hydroxyalkylphenol monomers described in formula Ia can be obtained. These compounds can also be synthesized from petrochemical substances. The 4-hydroxyalkylphenol monomers have two aliphatic diols and can be functionalized to give functionalized 4-hydroxyalkylphenol monomers (formula Ib). Either the 4-hydroxyalkylphenol (the above formula Ia) or their derivatized products (formula Ib) can be used in the synthesis of TPU as a short-chain diol (also called a chain extender) or as part of a polyol mixture.

Chemical formula

[0013] Generally, lignin-derived monomers, defined by formula I, or products resulting from their functionalization, are components of a reaction mixture that also includes diisocyanates and long-chain diols (also called polyols). When lignin-derived monomers are used as chain extenders, the composition may also include additional chain extenders, and one or more catalysts may be added as optional additions. The chemical and physical properties of TPUs can be fine-tuned by varying the types and ratios of various reagents. TPUs can be synthesized using conventional equipment, catalysts, and processes. In this process, various components can be bio-based.

[0014] Polymerization techniques useful for producing the TPU of the present invention include conventional methods such as reaction extrusion, batch processing, solution polymerization, reaction injection molding, and cast polymerization. (Partially) bio-based TPUs can serve as a substitute for petroleum-based TPUs.

[0015] In a first embodiment, the present invention relates to a lignin-derived monomer according to formula I, a lignin-type compound, or a product obtained by functionalizing these in the synthesis of thermoplastic polyurethane (TPU): [ka] Equation I (In the formula, R 1 and R 2 These are independently H or alkyl, particularly H or C 1-6 Alkyl, and more specifically H or CH3, R 3 and R 4 These are independently H or oxyalkyl, particularly H or oxyC 1-6 Alkyl, and more specifically H or OCH3, R 5 is H or hydroxyalkyl, especially H or hydroxyC 1-12 Represents alkyl, Provides the use of n (where n is between 0 and 3).

[0016] In another embodiment, the present invention provides thermoplastic polyurethanes (TPUs) comprising, namely, lignin-derived monomers of formula I, lignin-type compounds, or products obtained by the functionalization thereof.

[0017] The synthesis of thermoplastic polyurethane (TPU) according to the present invention comprises a reaction product of at least (a) an isocyanate composition, (b) a lignin-derived monomer, lignin-type compound, or a product obtained by functionalizing any one of these according to formula I, formula Ia, or formula Ib, and (c) a polyol composition. In this reaction, the lignin-derived monomer, lignin-type compound, or a product obtained by functionalizing any one of these according to formula I, formula Ia, or formula Ib functions as a chain extender. In one embodiment, no further chain extenders are used. In another embodiment, additional chain extenders are used.

[0018] In the lignin depolymerization process, polyols containing lignin-derived monomers, lignin-type compounds, or products obtained by the functionalization thereof according to any one of formulas I, Ia, or Ib can be similarly obtained. In the synthesis of thermoplastic polyurethane (TPU) according to the present invention, such polyols can be used as one of the reagents, so in one embodiment, the TPU according to the present invention is a reaction product of (a) an isocyanate, (b) a polyol composition containing as repeating units a lignin-derived monomer, lignin-type compound, or product obtained by the functionalization thereof according to any one of formulas I, Ia, or Ib, and (c) a chain extender. Such polyols can be used alone or in combination with other polyols. Therefore, in further embodiments, TPU is a reaction product of (a) an isocyanate, (b) a polyol mixture in which at least one of the polyols contains as a repeating unit a lignin-derived monomer, a lignin-type compound, or a product obtained by functionalization thereof, according to formula I, formula Ia, or formula Ib, and (c) a chain extender.

[0019] With respect to polyols, the chain extender may be a lignin-derived monomer, a lignin-type compound, or a product obtained by the functionalization of any one of formulas I, Ia, or Ib, or a combination with further chain extenders. In one embodiment, the thermoplastic polyurethane (TPU) according to the present invention comprises (a) an isocyanate, (b) a polyol mixture in which at least one of the polyols contains as repeating units a lignin-derived monomer, a lignin-type compound, or a product obtained by the functionalization of any one of formulas I, Ia, or Ib, and (c) an optional additional chain extender, comprising a reaction product with a lignin-derived monomer, a lignin-type compound, or a product obtained by the functionalization of any one of formulas I, Ia, or Ib that acts as a chain extender.

[0020] In the synthesis of thermoplastic polyurethane (TPU) according to the present invention, the isocyanate composition preferably comprises an aromatic diisocyanate, an aliphatic diisocyanate, an alicyclic diisocyanate, or any mixture thereof.

[0021] In a particular embodiment of the present invention, the lignin-derived monomer, lignin-type compound, or product obtained by functionalizing these used in the TPU synthesis according to the present invention has the following structure. [ka] Lignin-derived monomers Equation Ia [ka] Monomers derived from functionalized lignin Formula Ib (In the formula, R 1 and R 2 These are independently H or alkyl, particularly H or C 1-6 Alkyl, and more specifically H or CH3, R 3 and R 4These are independently H or oxyalkyl, particularly H or oxyC 1-6 Alkyl, and more specifically H or OCH3, n is between 0 and 3. m is between 1 and 12.

[0022] In certain embodiments, the lignin-derived monomers or products obtained by functionalization thereof as defined in the various embodiments described above exist as extracts of depolymerized lignin containing at least 80% by weight of the lignin-derived monomer of formula I, formula Ia, or formula Ib, and more particularly as extracts of depolymerized lignin containing at least 80% by weight of the lignin-derived monomer of formula III, and even more particularly, at least 90% by weight of the lignin-derived monomer of formula III.

[0023] In certain embodiments, the polyol composition used for TPU synthesis according to the present invention includes a polyether polyol, polyester polyol, polyacrylic polyol, polycarbonate polyol, polysiloxane polyol, or a mixture thereof, having a molecular weight of 200 to 8000.

[0024] As described above, the polyol composition may be based on a repeating unit consisting of a lignin-derived monomer according to formula I, formula Ia, or formula Ib, a lignin-type compound, or a product obtained by the functionalization thereof, or may contain a repeating unit consisting of a lignin-derived monomer according to formula I, formula Ia, or formula Ib, a lignin-type compound, or a product obtained by the functionalization thereof. Therefore, in one embodiment, the polyol composition contains a repeating unit consisting of a lignin-derived monomer according to any one of formula I, formula Ia, or formula Ib, a lignin-type compound, or a product obtained by the functionalization thereof, and optionally further contains a polyether polyol, polyester polyol, polyacrylic polyol, polycarbonate polyol, polysiloxane polyol, or a mixture thereof, having a molecular weight of 200 to 8000.

[0025] Lignin-derived monomers or products obtained by functionalization thereof, as defined in various embodiments herein, act as chain extenders in TPU synthesis according to the present invention, optionally in combination with additional chain extenders. In certain embodiments, the additional chain extender composition includes C2-C12 diols, diamines, and combinations thereof.

[0026] Depending on the lignin-based material, one, some, or all components of the TPU according to the present invention can be bio-based or are bio-based. The equivalent amount of diisocyanate to the active hydrogen-containing component is typically in the range of 0.3 to 2. The molar ratio of the polyol component to the full-chain extender (lignin-derived monomer + additional chain extender) is typically in the range of 99:1 to 1:99. In one embodiment, the molar ratio of the (functionalized) lignin-derived monomer to the additional chain extender is in the range of 99:1 to 1:99.

[0027] The TPUs described herein can be obtained by reactive extrusion, batch processing, solution polymerization, reactive injection molding, and cast polymerization, and can be used in a variety of applications, mainly as substitutes for petroleum-based thermoplastic polyurethanes.

[0028] In further embodiments, the present invention provides an extract of depolymerized lignin oil containing at least 80% by weight, particularly at least 90% by weight, of the monomer according to Formula III, and also provides the use of the extract in the synthesis of thermoplastic polyurethanes, or the use of monomers as defined herein, i.e., monomers of Formula I, Formula Ia, or Formula Ib, in the synthesis of thermoplastic polyurethanes. [Modes for carrying out the invention]

[0029] The TPU of the present invention comprises, in its composition, a lignin-derived monomer, a lignin-type compound, or a product obtained by the functionalization of each thereof. As already stated herein, the present invention uses a lignin-derived monomer, a lignin-type compound, or a product obtained by the functionalization of each thereof, which is usually represented by formula I and referred to as a lignin-derived 4-hydroxyalkylphenol monomer, as part of a short-chain diol (also called a chain extender) or polyol mixture in the synthesis of TPU.

[0030] In the first embodiment, the TPU of the present invention comprises a reaction product of (a) an isocyanate, (b) a lignin-derived 4-hydroxyalkylphenol monomer defined by any one of formulas I, Ia, or Ib, and (c) any long-chain diol (a polymeric diol also known in the art as a polyol).

[0031] In TPU synthesis, other chain extenders can also be used in addition to lignin-derived monomers. Thus, in the second embodiment, the TPU of the present invention comprises a reaction product of (a) an isocyanate, (b) a lignin-derived 4-hydroxyalkylphenol monomer defined by any one of formulas I, Ia, or Ib, (c) a long-chain diol (a polymeric diol also called a polyol in the art), and (d) an additional chain extender.

[0032] In a third embodiment, the TPU of the present invention comprises a reaction product of (a) an isocyanate, (b) a long-chain diol (a polymer diol also called a polyol in the art) containing a lignin-derived 4-hydroxyalkylphenol monomer defined by any one of formulas I, Ia, or Ib as a repeating unit, and (c) a chain extender.

[0033] In a fourth embodiment, the TPU of the present invention comprises a reaction product of (a) an isocyanate, (b) a long-chain diol mixture (also known in the art as a polymeric diol), of which at least one contains a lignin-derived 4-hydroxyalkylphenol monomer defined by formula I as a repeating unit, and (c) a chain extender.

[0034] In a fifth embodiment, the TPU of the present invention comprises a reaction product of (a) an isocyanate, (b) a mixture of long-chain diols (also called polyols in the art), of which at least one contains a lignin-derived 4-hydroxyalkylphenol monomer defined by formula I as a repeating unit, and (c) a lignin-derived 4-hydroxyalkylphenol monomer defined by any one of formula I, formula Ia, or formula Ib acting as a chain extender.

[0035] In each of the embodiments described above, the lignin-derived 4-hydroxyalkylphenol monomer may be 4-hydroxyalkylphenol (formula Ia), its derivative (formula Ib), or a combination thereof. In certain embodiments, the lignin-derived 4-hydroxyalkylphenol monomer used in TPU synthesis may be either 4-hydroxyalkylphenol according to formula Ia or a derivative according to formula Ib.

[0036] In each of the embodiments described above, the chemical and physical properties of TPU can be fine-tuned by changing the types and ratios of various reagents. TPU can be synthesized using conventional processing equipment, catalysts, and processes. In this process, various components can be bio-based.

[0037] Diisocyanate composition In one embodiment, the isocyanate suitable for synthesizing TPU may be any of the isocyanates previously disclosed as suitable for the preparation of TPU, and may include aliphatic diisocyanates, aromatic diisocyanates, alicyclic diisocyanates, and mixtures thereof.

[0038] Examples of diisocyanates include methylenebis(phenylisocyanate), 2,4-toluenediisocyanate and 2,6-toluenediisocyanate, including 4,4'-isomers, 2,4'-isomers and mixtures thereof, m-phenylenediisocyanate and p-phenylenediisocyanate, chlorophenylenediisocyanate, a,a'-xylylenediisocyanate, o-tolidinediisocyanate, and 1,5-naphthylene. Examples include, but are not limited to, methylenebis(cyclohexyl isocyanates) and cyclohexylenebis(cyclohexyl isocyanates) (1,2-, 1,3- or 1,4-, and mixtures thereof), including tallen diisocyanate, hexamethylene-1,6-diisocyanate, pentamethylene-1,5-diisocyanate, 1,4-butane diisocyanate, isophorone diisocyanate, 4,4'-isomers, 2,4'-isomers, and mixtures thereof. Modified forms of methylenebis(phenyl isocyanate) that can be stable liquids at ambient temperature are also examples. The dimers and trimers of the above-mentioned diisocyanates can also be used in TPU synthesis.

[0039] More preferably, the diisocyanate is selected from methylenebis(phenyl isocyanate) containing 4,4'-isomers, 2,4'-isomers, and mixtures thereof, 2,4-toluene diisocyanate and 2,6-toluene diisocyanate, and mixtures thereof, hexamethylene-1,6-diisocyanate, pentamethylene-1,5-diisocyanate, 4,4'-isomers, 2,4'-isomers, and mixtures thereof, methylenebis(cyclohexyl isocyanate).

[0040] Lignin-derived monomers In one embodiment, a lignin-derived monomer of formula Ia and / or a product obtained by functionalizing it (formula Ib) is used as a chain extender in TPU synthesis. In a particular embodiment, the lignin-derived monomer is defined by formula III, and the functionalized lignin-derived monomer is defined by formula IV. [ka] Lignin-derived monomers Formula III [ka] Monomers derived from functionalized lignin Formula IV (In the formula, R 1 and R 2 R independently represents H or CH3, 3 and R 4 This independently represents H or OCH3, n is between 0 and 3, and m is between 1 and 12.

[0041] In one embodiment, lignin-derived monomers defined by formula I, formula Ia, or formula Ib are used directly in TPU synthesis. The monomer composition in the depolymerized lignin depends on the type of lignocellulose selected as the starting material, as well as the depolymerization conditions and reaction. Several types of depolymerization methods, particularly the reductive catalytic method, can isolate 4-hydroxylalkylphenols defined by formula I, formula Ia, or formula Ib in good yield.

[0042] However, typically, 4-hydroxyalkylphenols defined by formula I, formula Ia, or formula III are R 1 and R 2 Each of them is independently H or CH3, and R 3 and R 4 Each of these is independently H or OCH3 (position R 1 , R 2 , R 3 and R 4It is obtained as a mixture of monomers (which change). The most common 4-hydroxyalkylphenol monomer is R 1 and R 2 H is R 3 OCH3 is R 4 This monomer is a monomer according to formula Ia, where is H or OCH3 and n is 3. Mixtures of such monomers can be used in the protocol described.

[0043] However, the depolymerization of lignin also yields other monomers, such as 4-alkylphenols (R=CH3) and higher molecular weight molecules (dimers, oligomers), in addition to these types of monomers, i.e., 4-hydroxyalkylphenols. While 4-hydroxyalkylphenols can be separated from 4-alkylphenols by chemical or physical means, some 4-alkylphenols may remain in the monomer mixture. On the other hand, if trifunctional monomers or oligomers are present in the mixture, they can act as branching components, potentially resulting in branched or partially crosslinked polymers. When a monomer mixture rich in 4-hydroxyalkylphenols is used as a chain extender, thermoplastic materials can be obtained by reducing the ratio of polyol to diisocyanate to less than 1. In addition to lignin-derived monomers, lignin-type compounds can be used. Lignin-type compounds are petroleum-derived compounds that replicate the structure of lignin-derived molecules. Therefore, although their origins differ, their molecular structures and, consequently, the properties of the resulting polymers are the same. Accordingly, in this patent, they are included in the term "lignin-derived monomers."

[0044] In one embodiment, a lignin-derived monomer is functionalized to obtain a dialiphatic diol (formula Ib). This reaction can be carried out using a variety of chemicals, for example, non-limitedly, cyclic ethers such as ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran or 5-methyltetrahydrofuran; cyclic carbonates such as ethylene carbonate and propylene carbonate; and haloalcohols such as 2-chloroethanol, 2-iodoethanol, 3-chloro-1-propanol, 3-bromo-1-propanol, and 4-chlorobutanol, 5-bromo-1-pentanol, 6-chlorohexanol, 8-chloro-1-octanol, 10-chloro-1-decanol.

[0045] Selective functionalization of phenolic hydroxyl groups can be achieved in various ways. One option is to use a base that deprotonates phenolic hydroxyls but not aliphatic hydroxyls. Examples of common bases that satisfy this criterion include ammonia and metal hydroxides M(OH) x Preferably alkali metal hydroxides (e.g., NaOH or KOH), formula M x (CO3) y Examples include, but are not limited to, carbonates containing (e.g., Na2CO3 or K2CO3).

[0046] In one embodiment, lignin-derived monomers and functionalized lignin-derived monomers can be converted to amino alcohols or diamines. These can also be used in TPU synthesis.

[0047] Short-chain diols (chain extenders) In some embodiments, lignin-derived monomers act as chain extenders. In other embodiments, standard short-chain diols (chain extenders) are used. In yet another embodiment, there are two chain extenders, namely a standard one and a lignin-derived monomer. In this last case, the molar ratio of lignin-derived 4-hydroxyalkylphenol monomer to additional chain extender can be 99:1 to 1:99, preferably 90:10 to 10:90, and most preferably 80:20 to 20:80. The additional chain extender includes diols, diamines, and combinations thereof having 2 to 12 carbon atoms.

[0048] Examples of chain extenders include, but are not limited to, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,3-butanediol, 1,5-pentanediol, neopentyl glycol, 2-ethyl-2-butyl-1,3-propanediol, 1,4-cyclohexanedimethanol, hexamethylenediol, heptanediol, nonanediol, dodecanediol, benzenedimethanol (1,2-, 1,3- or 1,4-, and mixtures thereof), bis(2-hydroxyethoxy)benzene (1,2-, 1,3- or 1,4-, and mixtures thereof), ethylenediamine, butanediamine, 1,2-propylenediamine, 1,6-hexamethylenediamine, piperazine, ethanolamine, N-methyl-diethanolamine, N-ethyldiethanolamine, N-phenylpropanolamine, and mixtures thereof.

[0049] Long-chain diols (polyols) In some embodiments, suitable long-chain diol (also called polyol) components for synthesizing TPU can be any from the categories of polyether polyols, polyester polyols, polyacrylic polyols, polycarbonate polyols, or polysiloxane polyols, or mixtures thereof, having a molecular weight of preferably 200 to 8000, more preferably 300 to 4000, and most preferably 400 to 2000.

[0050] In one embodiment, the polyol may include a polyether polyol. Suitable polyether polyols may include polyether polyols derived from diols or polyols reacted with alkylene oxides, typically ethylene oxide or propylene oxide, or mixtures thereof, with ethers. Examples of polyether polyols include, but are not limited to, poly(ethylene glycol), poly(propylene glycol), and poly(tetramethylene ether glycol), also known as polytetrahydrofuran. Suitable polyether polyols also include polyetheramines, particularly diamines, and polyamide adducts, such as reaction products of ethylenediamine and propylene oxide. Copolyethers obtained from the reaction of tetrahydrofuran with ethylene oxide or propylene oxide can also be used in the present invention. The polyether composition may include a mixture of polyethers.

[0051] In one embodiment, the polyol may include a polyester polyol. The polyester polyol is produced by either an esterification reaction of one or more glycols with one or more dicarboxylic acids or anhydrides, or a transesterification reaction of one or more glycols with esters of dicarboxylic acids. The dicarboxylic acid of the desired polyester may be aliphatic, alicyclic, aromatic, or a combination thereof. Exemplary examples of dicarboxylic acids include, but are not limited to, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, and mixtures thereof. Anhydrides of the above-mentioned dicarboxylic acids, such as phthalic anhydride, tetrahydrophthalic anhydride, and mixtures thereof may also be used. The glycol that reacts to form the desired polyester intermediate may be aliphatic, aromatic, or a combination thereof, and may include any of the glycols described in the section on chain extenders above. Examples include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, decamethylene glycol, dodecamethylene glycol, and mixtures thereof.

[0052] In one embodiment, the polyol may include a polyacrylic polyol.

[0053] In one embodiment, the polyol may include a polycarbonate polyol. A polycarbonate polyol can be produced by reacting a diaryl carbonate with a diol, such as propylene glycol, 1,4-butanediol, or 1,6-hexendiol, or a mixture thereof.

[0054] In one embodiment, the polyol may include a polysiloxane polyol. Polysiloxane polyols can be produced by a dehydrogenation reaction of a hydrogenated polysiloxane with an aliphatic polyhydric alcohol or a polyoxyalkylene alcohol. Exemplary examples include α-ω-hydroxypropyl-terminated poly(dimethylsiloxane), α-ω-aminopropyl-terminated poly(dimethylsiloxane), and copolymers of poly(dimethylsiloxane) material and poly(alkylene oxide).

[0055] In one embodiment, a polyol from any of the categories listed above (polyether polyols, polyester polyols, polyacrylic polyols, polycarbonate polyols, or polysiloxane polyols) contains at least one lignin-derived 4-hydroxyalkylphenol monomer, as defined by formula I, as a repeating unit. Polyols containing lignin-derived monomers can be synthesized according to any of the methods used to convert diols into polyols.

[0056] In one embodiment, the polyol is a mixture of polyols from any of the categories listed above (polyether polyols, polyester polyols, polyacrylic polyols, polycarbonate polyols, or polysiloxane polyols), wherein at least one of these polyols contains at least one lignin-derived 4-hydroxyalkylphenol monomer defined by formula I as a repeating unit.

[0057] TPU formulation The ratio of the total equivalent of all diisocyanates to the total equivalent of the active hydrogen-containing components (lignin-derived monomers acting as short-chain diols, any further short-chain diols (chain extenders), and long-chain diols (polyols)) is in the range of 0.3 to 2, more preferably 0.5 to 1.5, and most preferably 0.7 to 1.2. When using a lignin-derived mixture rich in 4-hydroxyalkylphenols containing molecules (dimers, oligomers) with a functional value greater than 2, the ratio of diisocyanates to the isocyanate-reactive groups used is less than 1. The molar ratio of polyols to total short-chain diols (lignin-derived monomers + any chain extenders) can be preferably 99:1 to 1:99, more preferably 90:10 to 10:90, and most preferably 80:20 to 20:80. The higher the proportion of short-chain diols, the harder the resulting TPU becomes.

[0058] A catalyst to facilitate the reaction between the isocyanate group and the isocyanate-reactive group (hydroxyl or amine) is not essential but can be used. The following two types of catalysts can be used independently: Tertiary amines, for example, non-limitingly, triethylamine, triethylenediamine, dimethylcyclohexylamine, N-methylmorpholine, N-ethylmorpholine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetraethylethylenediamine, N,N-dimethylethanolamine, N,N-diethylethanolamine, N,N'-dimethylpiperazine, N,N,N',N'-tetramethylguanidine, N,N,N',N'-tetramethyl-1,3-butanediamine, 2-(dimethylaminoethoxy)ethanol, diazabicyclo[2.2.2]octane, and mixtures thereof. Organometallic compounds, such as, without limitation, stannous octanoate, stannous oleate, lead octanoate, dibutyltin dioctanoate, dibutyltin dilaurate, dibutyltin diacetate, iron(III) acetylacetone, magnesium acetylacetone, bismuth neodecanoate, and mixtures thereof. The amount of catalyst used is usually in the range of 0.0001% to 1.0% by weight of the total weight of the reactants.

[0059] In addition to catalysts, conventional auxiliary agents and additives can also be added to the components, reaction mixture, or after TPU production. Examples of these include, but are not limited to, flame retardants, antioxidants, nucleating agents, stabilizers against hydrolysis, light, heat, oxidation or discoloration, surfactants, lubricants and release agents, dyes and pigments, inhibitors, antimicrobial agents, impact modifiers, rheological modifiers, UV absorbers, inorganic and / or organic fillers, reinforcing agents, and plasticizers. Chain modifiers may be optionally added. These compounds have only one functional group that is reactive with the isocyanate.

[0060] Polymerization techniques useful for producing the TPU of the present invention include conventional methods such as reaction extrusion, batch processing, solution polymerization, reaction injection molding, and cast polymerization.

[0061] (Partially) bio-based TPUs can be used as a substitute for petroleum-based TPUs, for example, not limited to, sporting goods, medical devices, mobile electronic devices, laptop keyboard protectors, automotive instrument panels, caster wheels, power tools, footwear, performance films, wire and cable jackets, adhesives and textile coatings, and 3D printing applications. [Brief explanation of the drawing]

[0062] [Figure 1] 1H NMR of a highly concentrated DCA mixture extracted from lignin. [Figure 2] 1H NMR of pure DCA extracted from lignin [Examples]

[0063] Lignin-derived monomers Lignin-derived monomers can be extracted from lignin or synthesized from petroleum-derived chemicals. Extraction of 4-(3-hydroxypropyl)-2-methoxyphenol (dihydroconiferyl alcohol, DCA) or 4-(3-hydroxypropyl)-2,6-dimethoxyphenol (dihydrosinapyrus alcohol, DSA) can be carried out according to the following method.

[0064] DCA and / or DSA can be extracted from depolymerized lignin oil containing this compound according to the extraction protocol. In one embodiment, DCA and / or DSA are extracted from depolymerized lignin oil with water. The lignin oil is mixed with water in a gram-to-ml ratio, preferably 1:1 to 1:100, more preferably 1:2 to 1:50, and most preferably 1:5 to 1:20 by mass. The lignin mixture in water is heated to the boiling point of water and stirred for a period of time from 5 minutes to 72 hours, preferably 10 minutes to 48 hours, and most preferably 20 minutes to 24 hours. After the corresponding time, the mixture is cooled to settle, and the aqueous layer is collected and filtered. The remaining lignin can be extracted again. The extraction cycle can be repeated several times to increase the yield of the extracted monomers. The aqueous layers are combined and mixed, and the water is removed to obtain a mixture highly concentrated with DCA and / or DSA, along with some DCA dimers and / or DSA dimers. Alternatively, DCA can be extracted from the aqueous phase using an organic solvent and then concentrated. The mixture can be further purified by column chromatography or crystallization.

[0065] In another embodiment, the depolymerized lignin oil can first be fractionated using an organic solvent in which DCA and / or DSA are soluble, such as, not limited to, diethyl ether, ethyl acetate, methanol, ethanol, tetrahydrofuran, dioxane, dichloromethane, acetone, ethyl methyl ketone, etc. Non-polar solvents, such as hexane and toluene, are not suitable. The fractionation involves stirring a certain amount of lignin in a certain volume of solvent, preferably in a gram-to-ml ratio of 1:1 to 1:100, more preferably 1:2 to 1:50, and most preferably 1:5 to 1:20. The lignin mixture in the solvent can be heated to the boiling point of the solvent. The stirring time is 10 minutes to 72 hours, preferably 1 hour to 48 hours, and most preferably 2 hours to 24 hours. After filtration, the soluble fraction is recovered and the solvent is removed. Sequential fractionation using different solvents is possible. The lignin fractionated with the solvent is richer in DCA and / or DSA compared to the starting lignin oil. Next, this fraction is separated with water. The lignin oil is mixed with water in a gram-to-ml ratio, preferably 1:1 to 1:100, more preferably 1:2 to 1:50, and most preferably 1:5 to 1:20 by mass. The lignin mixture in water is heated to the boiling point of water and can be stirred for a period of time from 5 minutes to 72 hours, preferably 10 minutes to 48 hours, and most preferably 20 minutes to 24 hours. After the corresponding time, the mixture is cooled to settle, the aqueous layer is collected and filtered. The remaining lignin can be extracted again. The extraction cycle can be repeated several times to increase the yield of the extracted monomers. The aqueous layers are combined and mixed, and the water is removed to obtain a mixture highly concentrated with DCA and / or DSA, along with some DCA dimers and / or DSA dimers (Figure 1, 1H NMR of the highly concentrated DCA mixture extracted from lignin). Alternatively, DCA and / or DSA can be extracted from the aqueous phase using an organic solvent and then concentrated. The mixture can be further purified by column chromatography, distillation, or crystallization (Figure 2: 1H NMR of pure DCA extracted from lignin).

[0066] DCA and DSA can also be synthesized from petroleum-derived chemicals (Examples 1 and 2, respectively). Example 1 4-(3-hydroxypropyl)-2-methoxyphenol, dihydroconiferyl alcohol (DCA) [ka] Following the modified literature procedure (Can. J. Chem. 1971, 49, 3394-3395), eugenol (18.9 mL, 122.0 mmol) was dissolved in anhydrous THF under an anhydrous atmosphere. The mixture was cooled to 0°C, and then boranedimethyl sulfide complex (15 mL, 158.2 mmol) was added dropwise over 20 minutes. After stirring at 0°C for 1 hour, the reaction mixture was carefully quenched with water (40 mL). Sodium hydroxide aqueous solution (3 M, 48 mL) was added, and the reaction mixture was cooled again to 0°C. Hydrogen peroxide aqueous solution (30%, 28 mL) was carefully added, and the solution was warmed to room temperature and stirred for 1.5 hours. The mixture was then poured into a beaker, and diethyl ether was added to precipitate the salt. The two layers were transferred to a separatory funnel and extracted using diethyl ether. After two extractions, the aqueous solution was acidified with hydrochloric acid, and then extracted two more times using diethyl ether. All organic layers were washed together with brine. The solvent was dried using magnesium sulfate and removed by filtration under vacuum. The resulting crude product was purified by recrystallization in a chloroform / carbon disulfide mixture. Colorless crystals were obtained in 73% yield. 1 H NMR (600 MHz, CDCl3) δ 6.83 (d, J = 7.9 Hz, 1H), 6.72 - 6.67 (m, 2H), 3.87(s, 3H), 3.68 (t, J = 6.4 Hz, 2H), 2.64 (t, J = 7.6 Hz, 2H), 1.91 - 1.83 (m,2H).

[0067] Example 2 4-(3-hydroxypropyl)-2,6-dimethoxyphenol, dihydrosinapyr alcohol (DSA) [ka] Under an anhydrous atmosphere, dihydrosinapic acid (8 g, 35 mmol) was dissolved in anhydrous THF and cooled to 0°C. Lithium aluminum hydride (3.00 g, 79 mmol) was gradually added over 1 hour. The reaction mixture was stirred overnight at room temperature. The reaction was rapidly cooled by slowly pouring the mixture into ethyl acetate and then adding water. The aqueous layer was extracted with ethyl acetate, and the organic layers were washed together with brine. The solvent was dried using magnesium sulfate, filtered under vacuum, and removed. The product was obtained as a yellow liquid in 91% yield. 1 H NMR (400 MHz, CDCl3) δ 6.42 (s, J = 3.8 Hz, 2H), 3.86 (s, J = 6.2 Hz, 6H),3.67 (t, J = 6.4 Hz, 2H), 2.63 (t, 2H), 1.91 - 1.82 (m, 2H).

[0068] Functionalization of lignin-derived monomers Whether synthetic or lignin-derived, 4-hydroxyalkylphenols can be functionalized.

[0069] Example 3 3-(4-(3-hydroxypropoxy)-3-methoxyphenyl)propan-1-ol, BA-DCA [ka] 4-(3-hydroxypropyl)-2-methoxyphenol (4.00 g, 22 mmol) was dissolved in isopropyl alcohol, followed by the addition of sodium hydroxide (1 g, 26.5 mmol, 1.2 equivalents). The mixture was stirred for 30 minutes, after which 3-chloro-1-propanol (2.4 mL, 28 mmol, 1.3 equivalents) was added. After the addition of 3-chloro-1-propanol, the reaction flask was refluxed for at least 24 hours. After the reaction was complete, the solvent was removed and water was added. The aqueous mixture was then extracted using ethyl acetate, and the organic phase was washed with brine. The solvent was dried using magnesium sulfate and removed by filtration under vacuum. The crude product was purified by column chromatography using ethyl acetate as the mobile phase. The product was obtained as a clear liquid in 86% yield and subsequently solidified as a white solid. 1 H NMR (600 MHz, CDCl3) δ 6.82 (d,J = 7.7 Hz, 1H), 6.73 - 6.70 (m, 2H), 4.16 (t, J = 5.8 Hz, 2H), 3.87 (t, J =5.5 Hz, 2H), 3.83 (s, 3H), 3.67 (t, J = 6.4 Hz, 2H), 2.75 (br),2.65 (t, J = 7.5 Hz, 2H), 2.05 (tt, J = 5.8, 5.5 Hz,2H), 1.87 (tt, J = 7.5, 6.4 Hz, 2H), 1.71 (br). 13 C NMR (101 MHz, CDCl3) δ 149.44,146.40, 135.38, 120.37, 113.60, 112.08, 68.71, 62.29, 61.58, 55.90, 34.49,31.89, 31.86.

[0070] Example 4 3-(4-(3-hydroxypropoxy)-3,5-dimethoxyphenyl)propan-1-ol, BA-DSA [ka] The compound was synthesized using 4-(3-hydroxypropyl)-2,6-dimethoxyphenol as a starting material, following the procedure of Example 3 described above. The product was obtained in a yield of 17%. 1 H NMR (400 MHz, CDCl3) δ 6.42 (s, 2H), 4.11 (t, J = 5.6 Hz, 2H), 3.91 (t, J = 5.5 Hz, 2H),3.83 (s, 6H), 3.69 (t, J = 6.4 Hz, 2H), 3.37 (s, 1H), 2.66 (t, J = 7.6 Hz, 2H), 2.06 (s, 1H), 1.99 - 1.84 (m, 4H). 13 C NMR (101 MHz, CDCl3) δ 153.02,138.00, 135.03, 105.36, 72.20, 62.17, 61.38, 56.09, 34.36, 32.64, 32.16.

[0071] Polymer synthesis TPUs can be synthesized using the lignin-derived monomers (DCA and / or DSA) or the functionalized lignin-derived monomers (BA-DCA and / or BA-DSA) described above, according to the following general protocol. In a dry round-bottom flask, the polyol (long-chain diol) was dissolved in dry DMF and stirred at approximately 80°C or 100°C. Diisocyanate (MDI or HDI) was added to this solution and reacted for 10 to 30 minutes. Then, a chain extender (lignin-derived monomer and, if present, additional chain extender) was added, followed by the addition of a catalyst (tin octanoate, 1 mol%). The mixture was reacted for 10 to 20 hours, particularly for at least 3 hours, and more particularly for 3 to 20 hours, then precipitated in water, and the solid, i.e., polymer, was filtered. The resulting polymer was then dried in a vacuum oven, or alternatively, the filtered polymer was dissolved in THF, poured into a mold, and dried in a vacuum oven.

[0072] Several polymers were characterized by gel permeation chromatography and differential scanning calorimetry. Some polymers exhibited two glass transition temperatures, one of which, corresponding to the hard phase, was very weak; this is not shown in the table.

[0073] [Table 1]

Claims

1. Formula Ib 【Chemistry 1】 (In the formula, R 1 and R 2 represents H or alkyl independently, R 3 and R 4 This independently represents H or oxyalkyl, n is between 0 and 3. m is between 1 and 12. A method for synthesizing thermoplastic polyurethane, comprising the reaction of a lignin-derived monomer, as defined by [definition], with an isocyanate composition and a polyol composition.

2. Use of a lignin-derived monomer defined by formula Ib, comprising the reaction of the lignin-derived monomer with an isocyanate composition and a polyol composition, in the synthesis of a thermoplastic polyurethane.

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