EP2408847A1

EP2408847A1 - Method for producing chemically modified lignin decomposition products

Info

Publication number: EP2408847A1
Application number: EP10709238A
Authority: EP
Inventors: Norman Blank; Irene Schober; Philipp Rudolf Von Rohr; Tobias Voitl
Original assignee: Sika Technology AG
Current assignee: Sika Technology AG
Priority date: 2009-03-20
Filing date: 2010-03-19
Publication date: 2012-01-25
Also published as: US20120012035A1; BRPI1009389A2; CN102395621A; WO2010106182A1

Abstract

The invention relates to a method for producing chemically modified lignin decomposition products. To this end, a lignin-containing starting material is decomposed into low-molecular and high-molecular lignin decomposition products under acid conditions in the presence of a liquid medium, and the low-molecular lignin decomposition products are at least largely separated in order to obtain a high-molecular fraction. Subsequently, the high-molecular lignin decomposition products present in the high-molecular fraction are converted into chemically modified lignin decomposition products. The chemically modified lignin decomposition products obtained in this way can be used, for example, as dispersing agents, complexing agents, phenol component, flocculant, thickener or auxiliary agents for cementous systems, coatings, paints or adhesives.

Description

PROCESS FOR PREPARING CHEMICALLY MODIFIED LIGNINA DERIVATIVES

Technical area

The invention relates to a process for the preparation of chemically modified lignin degradation products, their use as dispersants, and to a composition comprising a chemically modified lignin degradation product and a hydraulic binder.

Background Art Lignin, besides cellulose, is the most abundant material in living nature and is a major constituent of plants having the function of imparting rigidity to the cell scaffold. The lignin content can vary from plant to plant. The chemical structure of lignin also has plant-specific differences. Thus, depending on the type of plant, the macromolecule lignin is composed of different proportions of the monomers coniferyl alcohol, sinapyl alcohol and cumaryl alcohol, with the proportion of coniferyl alcohol dominating in many cases (especially in softwoods). In addition, there are numerous methods for separating the lignin from the other cell wall components, which in part considerably modify the chemical structure of the natural lignin.

While various processes for the production of chemicals from cellulose have reached the big-industrial scale, there are currently few economic opportunities to use the lignin content of biomass as a raw material for the production of chemicals. In papermaking, for example, large amounts of lignin fall as Nebenbzw. Waste product. Of the approximately 50 million tonnes of lignin produced each year in papermaking, only 1-2% are processed commercially. The use of lignin is limited mainly to relatively inexpensive dispersants and binders. Vanillin is the only lignin-based phenolic product that is commercially produced. One

Part of the world's vanillin production (12O00 tons / year) is realized by alkaline oxidative degradation of lignosulfonic acids.

Numerous methods of using lignin as a raw material are described in the literature. A frequently used approach is the gasification of biomass at high temperatures (800-1000 ⁰ C) with air and / or water vapor to synthesis gas (CO, H _2, CO ₂ and CH _4). From this synthesis gas various basic chemicals, such as methanol, ether, formic acid and higher molecular weight hydrocarbons (by Fischer-Tropsch synthesis), can be prepared in further stages.

Here, the originally existing complex chemical structure is completely lost. This decomposition and recombination strategy requires a lot of energy and produces unwanted by-products. In addition, only relatively cheap, cheap molecules can be produced with this method. For economic profitability large sales are necessary. Alternatively, various methods (eg, oxidative and non-oxidative hydrolysis, hydrogenolysis, pyrolysis) for the direct production of monomeric or low molecular weight chemicals are known. While these methods are suitable for breaking lignin into smaller fractions, no method is selective enough to produce a single product in high yield.

WO 2008/106811 describes a process for the direct production of molecules with a minimum molecular weight of 78 g / mol from lignin. For this purpose, lignin, lignin derivatives, lignin fragments and / or lignin-containing substances or mixtures in the presence of at least one

Polyoxometalat degraded to the desired products. Not to the

Target products converted lignin fragments or lignin are oxidized by means of oxygen to carbon dioxide and water or for energy

(eg thermal energy from oxidation) used. Lignins or lignosulfonates can be widely used. For example, US Pat. No. 6,313,055 and DE 101 16 849 A1 disclose lignosulfonates as dispersants or condenser for hydraulic binders.

DE 100 57 910 A1 discloses the treatment of lignin with a reactive spacer in order to convert low molecular weight constituents such that they are no longer volatile. So here's a chemical

Implementation of low molecular weight molecules revealed. As a result, however, these low molecular weight molecules or their derivatives remain in the lignin.

In addition, the low molecular weight molecules are not made available for any other use.

Presentation of the invention

The object of the present invention is to provide a simple and safe method for the chemical utilization of lignin, lignin derivatives, lignin fragments and / or lignin-containing substances or mixtures.

The object is achieved according to the invention by the process according to claim 1, the use according to claim 15 and the product according to claim 16. Preferred embodiments of the method are given in the dependent claims 2 to 14.

According to the process of the present invention, chemically modified lignin degradation products are prepared from a lignin-containing starting material. The method according to the invention comprises the following steps:

(A) degradation of a starting material which is selected from the group consisting of lignin, lignin derivatives, lignin fragments, lignin-containing substances and mixtures thereof under acidic conditions in the presence of a liquid medium to low molecular weight and high molecular lignin degradation products, wherein the low molecular weight Ligninabbauprodukte in their chemical Structural formula have a maximum of three benzene ring units and the high molecular lignin degradation in their chemical structural formula have more than three benzene ring units,

(B) at least substantial separation of the low molecular weight Ligninabbauprodukte to obtain a high molecular weight fraction and

(C) chemical modification of the high molecular weight lignin degradation products contained in the high molecular weight fraction to chemically modified Ligninabbauprodukten.

According to the invention, the chemical modification of the high-molecular-weight lignin degradation products according to step (c) takes place only after the steps (a) and (b).

The inventive method allows a chemical recovery of high molecular lignin degradation products and thus offers a more technologically valuable and useful alternative to the previously known methods for oxidation or energy by burning. The chemically modified Ligninabbauprodukte are for example extremely well as dispersants, for example for cementitious systems, as complexing agents for polyvalent metal cations, as a phenol component in binders or resins, or as flocculants, thickeners, components or auxiliaries for coatings, paints, adhesives or resins. The method according to the invention thus makes possible a very useful and meaningful utilization of the renewable raw material lignin. The degradation of lignin can increase the number of chemically modifiable functional groups in the degraded high-molecular-weight lignin molecules. In addition, additional, chemically modifiable functional groups that are not accessible without degradation can be introduced into the degraded high-molecular-weight lignin molecules. This leads to greater flexibility with regard to the use of chemically modified lignin degradation products. The chemical modification offers additional possibilities of functionalization and thus the possibility of further adapting the properties of the end product to the desired requirements. Due to the degradation of lignin, the molecular weight of the chemical is modified Ligninabbauprodukte after step c smaller than that of the same chemically modified undegraded starting lignins. The smaller molecular weight facilitates the solubility of the final products, improves the compatibility with other components, such as in formulations of cement liquefiers with other polymers, and improves the dispersing effect.

The chemically modified lignin degradation products obtained according to the invention have no or very low levels of low molecular weight lignin degradation products or chemically modified low molecular weight lignin degradation products due to step b. The presence of such, in particular phenolic, low molecular weight lignin degradation products or chemically modified low molecular weight lignin degradation products is particularly undesirable because they may be toxicologically disadvantageous on the one hand or because, especially when used in curable materials, such as concrete or mortar, washed out after or during curing or can be dissolved out, whereby the properties, in particular the environmental compatibility, of these cured materials is unfavorably influenced.

The low molecular weight lignin degradation products separated off in step (b), for example vanilin, can be used in other ways.

Thus, with the present process of lignin, both commercially interesting low molecular weight lignin

Mining products, as well as higher-value higher-molecular-weight lignin degradation products, thereby enabling the highest possible added value from the raw material lignin.

The term lignin describes a whole class of substances. This is known to the person skilled in the art.

With the method according to the invention, in principle, chemically modified lignin degradation products can be obtained from all lignin types, regardless of origin and pretreatment. It is also possible to have a aimed at pretreatment of the lignin used, for example, to modify the solubility in organic or inorganic solvent. Furthermore, it is also possible to use an already partially decomposed lignin.

Degradation takes place by cleavage of bonds in the lignin backbone, which reduces the molecular weight of the lignin and thus leads to degradation products which, depending on the molecular weight, are low molecular weight or high molecular weight lignin degradation products within the meaning of this document.

In a preferred embodiment, the degradation according to step (a) of the process according to the invention is carried out in the presence of at least one polyoxometalate. In contrast to the conventional methods for the degradation of lignins, which are usually based on purely chemophysical methods (high temperature and pressure), based on simple acid- or base-catalyzed hydrolysis, here Polyoxometallate allow the selective cleavage of bonds and thus the degradation of lignin already at comparatively low temperatures. The use of polyoxometalates as catalysts for the degradation of lignin, lignin derivatives, lignin fragments, lignin-containing substances and mixtures is described in WO 2008/106811, the disclosure of which is expressly incorporated herein by reference.

With regard to possible polyoxometalates, reference is also made to WO 2008/106811, where they are described in detail, Okuhara et al. (2001) Applied Catalysis A: General 222: 63-77, the disclosure of which is expressly incorporated herein by reference.

Polyoxometalates of molybdenum and phosphorus have been found to be particularly suitable. Most preferred phosphomolybdic acid (H3PM012O40 as representable), which is also referred to by the skilled person as 12-Phosphomolybdänsäure. Polyoxometalates are preferably used in step (a) in an amount of 0.01-50 g, preferably 0.1-10 g, per 1 g of starting material.

In a further preferred embodiment, the degradation according to step (a) is carried out in the presence of at least one acid, in particular in the presence of an acid having a pK _a i of less than 3, preferably less than 2.5. The use of an acid provides a simple and cost effective alternative to the polyoxometalate catalysts. Advantageous in the use of such acids is that the acids can be readily neutralized and without adversely affecting the chemical modification in step (c) without separation. On the contrary, it can also be advantageous that these acids even support or catalyze the chemical modification. Most acids are also less expensive than the polyoxometalates. It is possible to use both inorganic and organic acids, for example HCl, H ₂ SO ₄ , H ₂ SO ₃ , HNO ₃ , HNO ₂ , H ₃ PO ₄ , H ₃ PO ₃ , sulfonic acids, in particular benzenesulfonic acid, methanesulfonic acid or trifluoroacetic acid , Trichloroacetic acid.

In step (a), such acid (s) may also be used in combination with polyoxometalate (s).

An embodiment of step (a) provides a starting material selected from the group consisting of lignin, lignin derivatives,

Lignin fragments, lignocellulosic substances and mixtures thereof, in

Presence of at least one polyoxometalate or at least one

Reacting acid in a suitable reactor. This will be the

Starting material and the at least one polyoxometalate or the at least one acid dissolved or suspended in a suitable liquid medium. The mixture is left on for a sufficiently long time

Brought conditions that promote the degradation of lignin.

In this case, the pH can be in the range of 0.5 to 6 or be set, preferably in a range of 1 to 3. Under these acidic conditions, an optimal implementation of the lignin-containing starting material used to the low and high molecular weight

Ligninabbauprodukten. Preferably, the degradation of the lignin-containing starting material is carried out at a temperature of 20 to 300 ⁰ C, in particular at a temperature of 100 to 200 ⁰ C.

The degradation of lignin can be carried out at an overpressure of 0 to 200 bar, preferably at an overpressure of 0 to 50 bar. Preferably, the degradation takes place in the presence of N ₂ , air or O ₂ , preferably O ₂ .

Particularly good results of the degradation, ie particularly high yields of low molecular weight Ligninabbauprodukten were achieved when the degradation in a reactor at an excess pressure of oxygen and a temperature of 100 to 200 ⁰ C and in the presence of an acid having a pK _a i of less than 3 and / or a polyoxometalate.

The degradation of lignin in step (a) can also take place in a continuous process instead of in a batchwise, batchwise process. This has the particular advantage of lower labor and cleaning costs and therefore represents a cost reduction of the degradation process and is particularly preferred for industrial, large-volume lignin degradation or chemical modification of Ligninabbauprodukte particularly. Advantageously, in such a continuous process, the advantageously used polyoxometalates are continuously separated from the reaction mixture and recycled to the process.

According to a preferred embodiment, the degradation according to step (a) is carried out in the presence of at least one compound which prevents recombination of degradation products. In particular, such compounds are radical scavengers.

The following defines how the term "radical scavenger" is understood in the context of this document.

Radical scavengers serve in the context of this invention to scavenge the radicals formed during the degradation of lignin and thus to prevent repolymerization reactions. In particular, so should the Yield of the desired chemically modified lignin degradation products can be increased.

In a preferred embodiment, the degradation is carried out in the presence of a radical scavenger which is selected from the group consisting of alcohols, preferably methanol or ethanol; organic

Acids, preferably ascorbic acid; Phenols, preferably butylhydroxytoluene; and stabilized free radicals, preferably nitroxyl radicals.

Another embodiment provides to convert lignin-containing starting material in the presence of two liquid phases. In contrast to degradation in only one liquid phase, two liquid phases, which are only partly or immiscible, are in contact with each other. Preferably, the two liquid phases have a substantially different polarity. Due to different solubilities of polyoxometalate (s) or acid, of lignin and of lignin degradation products in the selected liquid phases, a partial or complete separation of the components can take place. For example, it is possible to choose a two liquid phase system wherein lignin, the high molecular weight lignin degradation products and polyoxometalate (s) are dissolved or suspended primarily in the first liquid phase (eg water) and the second liquid phase is higher Solubility for the low molecular weight Ligninabbauprodukte offers (eg chloroform). Thus, the low molecular weight Ligninabbauprodukte can be separated from the reaction medium before they react further in subsequent reactions. Preferably, the degradation of the lignin in the presence of two liquid phases is also carried out in the presence of a radical scavenger. It is advantageous if the liquid medium used in step (a) is water, optionally in combination with an alcohol. Preferably, an alcoholic radical scavenger is used in the degradation, in particular methanol and / or ethanol, wherein the volume ratio of water to alcoholic radical scavenger is particularly preferably in the range from 1:10 to 10: 1.

The at least substantial separation of the low molecular weight Ligninabbauprodukte can, for example, by distillation or extraction or precipitation or filtration or ultrafiltration. Extraction and ultrafiltration by means of membrane, which typically has a cut-off of 100 daltons or 1000 daltons, have proven particularly suitable. In addition, it is also possible, in addition to the low molecular weight lignin degradation products also separate any other components, eg. As solvents or excess reagents.

It has been found that, with as complete a separation as possible of the low molecular weight lignin degradation products, the advantages found in the context of the present invention are as strong as possible.

In a preferred embodiment, the separation of the low molecular weight lignin degradation products in step (b) is such that the proportion of the sum of low molecular weight lignin degradation products and chemically modified low molecular lignin degradation products less than 20 wt .-%, in particular in the chemically modified Ligninabbauprodukt after step (c) less than 10 wt%, preferably less than 5 wt%, most preferably less than 1 wt%.

It has been shown that particularly the separation of the low molecular weight constituents, which have only one benzene ring (referred to in this context as "monomers") corresponding to a molecular weight Mw of the low molecular weight degradation products of less than 200 g / mol, advantageously takes place as completely as possible the amount of monomers present in the reaction mixture after step (a) is separated off by means of step (b) to more than 90% by weight, in particular more than 95% by weight, preferably more than 97% by weight the high molecular weight fraction after step (b) less than 5 wt .-%, in particular less than 2 wt .-%, preferably less than 1 wt .-% of monomers.

It is basically possible to carry out step (b) during step (a), i. that the separation of the low-molecular

Lignin degradation products at least partially during the degradation of the Starting material can be carried out, for example by extraction in one operation (reactive extraction) or by separation (filtration) via a membrane in a membrane reactor.

The phenolic products separated as low-molecular-weight lignin degradation products can be used for a different purpose, for example as starting materials for the preparation of organic compounds.

By the chemical modification in step (c), the chemical properties of the high molecular weight lignin degradation products can be determined such that the modified products are suitable for the desired use. Depending on the intended use, the high-molecular lignin degradation products can be chemically modified, for example, by etherification, esterification, alkoxylation, sulfonation or graft polymerization. Preferably, the chemical modification of the high molecular weight lignin degradation products comprises a reaction selected from the group consisting of addition, condensation and graft polymerization.

The high molecular weight lignin degradation products contain after step (b) in particular chemically modifiable groups which are selected from the group consisting of aliphatic alcohol groups, aromatic alcohol groups (phenolic groups), carboxylic acid groups and carbonyl groups. In addition, they may possibly emerge as radicals from step (b). In particular, such groups are the chemical modification in step (c) accessible.

Furthermore, typical reactions on aromatic nuclei, such as electrophilic substitutions, can be carried out as a chemical modification in step (c). In a preferred embodiment, the chemical

Modification of the high-molecular lignin degradation products by reaction with at least one reactant which is selected from the group consisting of alcohols, carboxylic acids, hydroxycarboxylic acids, amino acids, acid chlorides, acid anhydrides, sulfonic acids, hydroxysulfonic acids, aminosulfonic acids, sulfamic acid, esters, lactones, lactams, alkyl halides, epoxides , Amines, hydroxylamines, sulfuric acid, oleum, Chlorosulfonic acid, adducts of SO3 such as DMF or pyridine, and olefinically unsaturated compounds.

As examples of such particularly preferred addition or condensation reactions, some typical chemical modification reactions are shown below schematically:

- Chemical modifications of alcohol groups of high-molecular-weight lignin degradation products: alkoxylation:

Phenolic and non-phenolic alcohol groups in the high-molecular-weight lignin decomposition products can be reacted with ethylene oxide, propylene oxide or butylene oxide or mixtures thereof, for example, under conditions customary for alkoxylations. Depending on the reaction control and the amount of alkylene oxide used, polyalkylene oxide chains of different lengths and compositions can be applied to the degraded lignin molecule. As a typical example of this, the following chemical groups can be introduced by means of alkoxylation:

In the above and the following formulas, the radical L linked via a dashed bond is intended in each case to represent the polymer backbone of a high-molecular-weight lignin degradation product before and after the chemical modification. It goes without saying that it is certainly also possible to append a number of - even different - of the functionalities shown to such a polymer backbone. - Chemical modifications of alcohol groups of high-molecular-weight lignin degradation products: addition of epoxides:

Phenolic and non-phenolic alcohol groups in the high molecular weight lignin degradation products can be further added to epoxides such as epoxidized fatty acids, glycidyl methacrylate or epoxidized maleic acid. As a typical example, the following chemical modified groups can be obtained by addition to epoxides:

- Chemical modifications of alcohol groups of high-molecular lignin decomposition products: Hetero-Michael addition: Possible alcohol groups present in the degraded lignin can with

Compounds containing activated C = C double bonds are etherified in a hetero-Michael addition. Examples of suitable compounds are (meth) acrylic acid, (meth) acrylates, (meth) acrylamides, (meth) acrylonitrile, vinylsulfonic acid or vinylphosphonic acid. Further possible compounds are maleic acid, crotonic acid or itaconic acid or their mono- or diesters and -amides and also the monoamide of maleic acid with sulphanilic acid. As a typical example, the following chemically modified groups can be obtained by addition to activated C =C double bonds:

- Chemical Modifications of Alcohol Groups of High Molecular Lignin Degradation Products: Esterification:

Phenolic and non-phenolic alcohol groups in the high molecular weight lignin degradation products can be esterified with mono- or dicarboxylic acids or their anhydrides or acid chlorides, or transesterified with simple carboxylic acid esters. Examples of these are acetic acid, maleic acid, fumaric acid, phthalic acid or Fatty acids such as lauric acid or oleic acid, their anhydrides, acid chlorides or simple esters. As a typical example of this, the following chemical modified groups can be obtained by esterification:

Chemical Modifications of Phenolic Groups of High Molecular Lignin Degradation Products: Methylolation & Mannich Base Preparation: Aromatic nuclei with aromatic alcohol groups, i.e., phenolic rings, can react with formaldehyde to form methylol compounds which can be further reacted. Reaction of the aromatic nuclei, in particular the phenolic rings, with formaldehyde or other aldehydes and amines or polyamines leads to Mannich bases. Alanine has been shown to be particularly suitable amine. These can be further functionalized as needed. As typical examples, the following chemical modified groups can be obtained:

- Chemical Modifications of Carboxylic or Carboxylic Ester Groups of High Molecular Lignin Degradation Products: Esterification, Amidation: Carboxylic acid or carboxylic ester groups in the high molecular lignin degradation products can be converted into the corresponding esters or amides with alcohols or amines or with epoxides.

Examples of such reactions are the esterification or amidation with α-alkoxy-ω-hydroxy-polyalkylene glycols or α-alkoxy-ω-amino-polyalkylene glycols, preferably α-methoxy-ω-hydroxy-polyethylene glycols, α-alkoxy-ω- amino-polyethylene glycols or α-alkoxy-ω-amino-poly (ethylene / propylene glycols), or the esterification with fatty alcohols such as lauryl alcohol or oleyl alcohol.

- Chemical modifications of aldehyde or ketone groups of high molecular weight lignin degradation products:

Aldehyde or keto groups in the high molecular weight lignin degradation products can be converted with sulfite to the corresponding hydroxy sulfonic acids. As a typical example of this, the following chemical modified groups can be obtained from aldehyde groups:

Furthermore, the high molecular weight lignin degradation products can be reacted in a radical graft polymerization with at least one olefinically unsaturated compound. The at least one olefinically unsaturated compound is preferably selected from the group consisting of alkenes, dienes, olefinically unsaturated acids, olefinically unsaturated esters, olefinically unsaturated acid anhydrides, olefinically unsaturated amides, olefinically unsaturated ethers and olefinically unsaturated alcohols, preferably selected from the group consisting of acids or anhydrides or esters or amides of acrylic acid, methacrylic acid, maleic acid, fumaric acid or itaconic acid, vinyl ethers, vinylsulfonic acids, vinyl esters, allyl alcohol and allyl ether. In particular, such olefinically unsaturated compounds are (meth) acrylic acid, maleic acid, fumaric acid, crotonic acid or itaconic acid, their esters, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, (meth) acrylamide, 2-acrylamido-2-methyl-1-propanesulfonic acid , the half-amide of maleic acid and sulphanilic acid, polyalkylene glycol (meth) acrylates or maleic acid-polyalkylene glycol mono- or maleic acid polyalkylene glycol diesters or amides, styrene, styrenesulfonic acid, vinyl acetate, N-vinylpyrrolidone, vinylpolyalkylene glycols, vinylsulfonic acid, vinylphosphonic acid or allyl polyalkylene glycols.

These graft (co) polymerizations are generally carried out with a suitable initiator and, if necessary, molecular weight regulators and / or reducing agents. Examples of initiators are peroxides such as hydrogen peroxide or dibenzoyl peroxide (DBPO), persulfates such as sodium, potassium or ammonium persulfate, hydroperoxides such as cumene hydroperoxide or azo compounds such as aziosobutyronitrile (AiBN). Preference is given to hydrogen peroxide and persulfates. Suitable regulators are, for example, allyl compounds, alcohols, aldehydes, sulfur compounds, e.g. Mercaptans, such as thioacetic acid, mercaptopropionic acid, dodecyl mercaptan, suitable reducing agents are, for example, alkali metal sulfites or alkali hydrogen sulfites, alkali phosphites, ascorbic acid, thiosulfates or Rongalit or transition metals, for example. Fe (II) salts.

The graft polymerization is preferably carried out with H ₂ O ₂ together with Fe (II) sulfate and Rongalit or with alkali persulfate and alkali metal sulfite. However, if water-insoluble monomers are used, the polymerization is preferably carried out in an organic solvent. In this case, it is advisable to use initiator systems that are soluble in organic solvents such as AiBN or DBPO.

Furthermore, typical reactions on aromatic nuclei, such as electrophilic substitutions, can be carried out as a chemical modification in step (c). Aromatic nuclei, especially phenolic rings, in the high molecular weight

Lignin degradation products can be used, for example, with oleum or sulfuric acid be sulfonated or sulfomethylated with formaldehyde and sulfite. As a typical example, the following chemical modified groups can be obtained:

It is clear to the person skilled in the art that within the scope of the invention it is also possible to carry out a plurality of reaction steps for the modification in succession or else simultaneously. Thus, for example, a high-molecular-weight lignin degradation product can be alkoxylated in a first step and, in a second step, the resulting and the remaining alcohol groups can be esterified. Or, in a first step, amino groups are introduced, which are reacted with epoxides in a second step. Or it is sulfonated in a first step on the aromatic and in a second step, the alcohol groups reacted with alkylene oxide. Also, more than one functional group can be implemented simultaneously, e.g. the alkoxylation can be carried out simultaneously on the aromatic and on the aliphatic alcohol group.

The degradation of the starting material is advantageous from very distinctive

Extent. This greatly reduces the molecular weight. By "molecular weight" in the present document is always understood the weight average molecular weight M _w , which via SEC (Size

Exclusion Chromatography).

The SEC analysis was performed on an HPLC system (Alliance 2695,

Waters) equipped with a column cascade from the company Polymer Standards Service GmbH (MCX 10μm 1000Ä, MCX 10μm 100000Ä + precolumn) and a UV detector (320nm) carried out. As eluent and solvent for Lignin and the lignin degradation products were used 0.01 molar aqueous sodium hydroxide solution. The calibration was carried out by means of 9 narrow polymer standards of sulfonated polystyrene in the molecular weight range 1O20O00 Da to 3'420 Da. The weight average molecular weight was thus determined relative to sulfonated polystyrene.

In a preferred embodiment, the weight average molecular weight M _{w of} the high molecular lignin degradation products after step (a) is less than 80% of the molecular weight of the starting material used in step (a), preferably less than 60%. Thus, the degradation which takes place in step (a) advantageously leads to a very marked reduction in the molecular weight and thus to a strong degradation of the lignin.

The present invention further relates to the use of a chemically modified lignin degradation product prepared by a process according to the invention as a dispersant. Alternatively, the chemically modified lignin degradation products may also be used as complexing agents for polyvalent metal cations, as a phenolic component in binders or resins, or as flocculants, thickeners, component or auxiliaries for coatings, paints, adhesives or resins.

The present invention further relates to a composition comprising at least one chemically modified lignin degradation product prepared by a process according to the invention and at least one hydraulic binder.

As a "hydraulic binder", this document basically refers to all hydraulically setting substances known to the skilled worker, in particular the hydraulic binders are cements, such as Portland cements or high-alumina cements and their mixtures with fly ash, silica fume, slags, slag sands However, hydraulic binders are also understood as meaning the hydraulically setting substances gypsum, in the form of anhydrite or hemihydrate, or calcined lime. Cement is preferred as the hydraulically setting binder. The composition may have other ingredients in addition to hydraulic binder and chemically modified Ligninabbauprodukt. Such other ingredients include additives such as sand, gravel, stones, quartz, chalk, Kalksteinfiller and customary additives such as Betonverfüssiger, such as lignosulfonates, sulfonated naphthalene-formaldehyde condensates, sulfonated melamine-formaldehyde condensates or polycarboxylate, accelerators, corrosion inhibitors, retarders, Schwindreduzierer Defoamer or pore-forming agent.

Such compositions cure as a result of the reaction of the hydraulic binder with water under the influence of water. In particular, such compositions may be used as mortar or concrete compositions.

It was found that the chemically modified lignin degradation products are best suited as dispersants, in particular as dispersants for hydraulic binders, in particular for cement and gypsum.

The chemically modified Ligninabbauprodukte also have a liquefying effect on hydraulic binders, or on compositions containing hydraulic binders. This means that, using a chemically modified lignin degradation product described above, a hydraulic binder or a composition comprising a hydraulic binder has a more fluid consistency or increased flow behavior than the corresponding hydraulic binder or the composition comprising the hydraulic binder, without chemically modified lignin degradation products with the same amount of water. In other words, the chemically modified lignin degradation products reduce the water requirement of a hydraulic binder, or a composition comprising the hydraulic binder, in order to achieve a specific flow behavior. The flow, or the flow behavior, is typically determined by the so-called slump size, measured according to EN 1015-3.

It has been found to be particularly advantageous that the chemically modified Ligninabbauprodukte described in the context of this invention in particular have a higher liquefaction effect for hydraulic binders, compared both with the corresponding chemically modified Ligninabbauprodukten where the low molecular weight Ligninabbauprodukte have not been separated before the chemical modification, as well as with the corresponding chemically modified lignins, which were not subjected to lignin degradation before the chemical modification , The higher liquefaction effect of the chemically modified Ligninabbauprodukte disclosed in the invention in hydraulic binders affects in improved processing properties, or in a lower water demand for the achievement of a specific processing consistency, which shows experience shows higher mechanical properties of the cured hydraulic system. On the other hand, the same processing consistency can be achieved even with a greatly reduced addition of chemically modified Ligninabbaudrodukten compared to the corresponding known undegraded lignins, despite the cost of degradation, separation and chemical modification slightly more expensive raw material costs nevertheless high savings in the end use can lead.

It has also been found that the low molecular weight lignin degradation products formed during lignin degradation can be separated easily and very efficiently, which is extremely advantageous and commercially highly attractive for their recovery and other uses.

The process presented in this document thus has a considerable potential in lignin, a natural raw material which is also present in large quantities and is also a waste product

To create value and thereby produce little or no waste products. Examples

The following examples serve to illustrate the invention and are by no means to be construed as limiting the invention.

For the examples, the following lignins were used:

• Lignin 1: Indulin® AT, an unmodified Kraft lignin from MeadWestvaco (USA), available for example from Staerkle & Nagler AG, Zollikon, Switzerland • Lignin 2: weakly sulphonated spruce kraft lignin supplied by Sigma Aldrich, Switzerland

Liqninabbau using sulfuric acid / separation

Example 1: Lignin 1 / Extraction via extraction. A mixture of 80 ml of methanol and 20 ml of water was added as

Reaction solution prepared. The pH of the solution was adjusted to pH 1.10 by addition of a few drops of concentrated sulfuric acid with simultaneous measurement with a Polilyte HT120 sensor (Hamilton Bonaduz AG, CH-Bonaduz). The solution was then transferred to a 400 ml autoclave (Premex Reactor AG, CH-Lengnau) equipped with a gassing stirrer. Before closing the reactor, 1 g of lignin 1 was added. The mixture was then charged three times with 11 bar of oxygen and then vented again to displace the initial air in the reactor. Finally, the reactor 11 was filled bar oxygen, and the mixture was heated at a stirrer speed of 1000 rev / min at a rate of 8 K / min to 170 ⁰ C. The mixture was kept at 170 ^° C. for 20 minutes and then cooled to below 30 ^° C. within 60 minutes. Thereafter, the reactor was depressurized, opened and the liquid reaction mixture (including the resulting solid) removed. In order to recover the degraded lignin as completely as possible from the reactor, the interior of the reactor was freed from solid deposits, the reactor was rinsed with a little water and the wash water added to the reaction mixture. This reaction mixture is referred to below as RG1.

After filtering off the solid S1, the filtrate was extracted three times with 30 ml of chloroform in a separating funnel and the extract was separated. The combined chloroform extracts are referred to as Ex-CI and the aqueous phase as Ex-WI. Ex-WI contained virtually no lignin degradation products.

The solid S1 was predried on a rotary evaporator and finally freeze-dried and designated as a separated high-molecular lignin degradation product AHLA1.

• Example 2: Lignin 21 separation via extraction

Example 2 was carried out in an analogous manner to Example 1, except that instead of the lignin 1 lignin 2 was used. The corresponding reaction mixture is hereinafter referred to as RG2, the solid as S2, the chloroform extract as Ex-C2 and the aqueous phase as Ex-W2. Since the aqueous phase Ex-W2 still contained lignin degradation products, in Example 2 the solid S2 was combined with aqueous phase Ex-W2, mixed, pre-dried on a rotary evaporator and finally freeze-dried and the separated high-molecular lignin degradation product designated AHLA2.

Example 3: Lignin 2 (larger autoclave) / separation via ultrafiltration

Example 3 was carried out in an analogous manner to Example 1, except that instead of the lignin 1 lignin 2 was used and a larger amount of lignin was used. The corresponding reaction mixture is hereinafter referred to as RG3. This reaction mixture was adjusted to pH 10.7 with NaOH and concentrated on a rotary evaporator and then freeze-dried. Of the 7.5 g of solid obtained, the majority of the low molecular weight decomposition products and the salts were separated by ultrafiltration with a 1000 Dalton membrane. In ultrafiltration, the solution is stirred in each case The ultrafiltration cell (300 ml volume) was separated at a pressure of about 4 bar via a membrane with a specified exclusion limit (for example 1000 daltons here). The phase passed through the membrane is referred to as filtrate, the remaining phase is referred to as residue. The filtrate obtained here was designated as filtrate F3. The residue was concentrated on a rotary evaporator and freeze-dried. 1.3 g of a powder having an organic carbon content of 48.0% (determined by TOC measurement) were obtained. This residue is the separated high molecular weight lignin degradation product and is referred to as AHLA3. The total organic carbon (TOC) indicated in this document

Values were determined in each case by measurements with a Sievers 5310C, Laboratory TOC Analyzer from Ionics Instruments in a known manner.

Lignin degradation by POM: H ^ PMo ^ OW separation • Example 4: Lignin 21 separation via extraction

9.128 g of H3PM012O40 (phosphomolybdic acid, No. 31426, Sigma-Aldrich, CH Buchs) were dissolved in a mixture of 80 ml of methanol and 20 ml of water, which corresponds formally to a 0.05 molar solution. The pH of the solution was then determined to be 1.13 with a Polylite HT120 sensor (Hamilton Bonaduz AG, CH-Bonaduz). The solution was then transferred to a 400 ml autoclave (Premex Reactor AG, CH-Lengnau) equipped with a gassing stirrer. Before closing the reactor, 1 g of lignin 2 was added. The mixture was then charged three times with 11 bar of oxygen and then vented again to displace the initial air in the reactor. Finally, the reactor 11 was filled bar oxygen, and the mixture was heated at a stirrer speed of 1000 rev / min at a rate of 8 K / min to 170 ⁰ C. The mixture was kept for 20 minutes at 170 ⁰ C and then cooled within 60 min to below 30 ° C. Thereafter, the reactor was depressurized, opened and the liquid reaction mixture (including small amounts of solid) removed. Around To remove the degraded lignin as completely as possible from the reactor, the interior of the reactor was freed from solid deposits, the reactor rinsed with a little water and the wash water added to the reaction mixture. This reaction mixture is referred to below as RG4. After filtering off the solid S4, the filtrate was extracted three times with 30 ml of chloroform in a separating funnel and the extract was separated. The combined chloroform extracts are designated Ex-C4 and the aqueous phase Ex-W4. Solid S4 and the aqueous extract Ex-W4 were combined, mixed, the pH adjusted to about 10 with NaOH and predried on a rotary evaporator and finally freeze-dried and referred to as a separated high molecular lignin degradation product AHLA4.

In each case several corresponding reactions were carried out to provide enough material of Examples 1 to 4 for the chemical reactions and tests available.

Chemical conversion

Sulfation of the separated high-molecular lignin degradation product AHLA1: B1 1.0 g of the separated high molecular lignin degradation product

AHLAI was almost completely dissolved in 10 ml of dry DMSO and 0.22 g of sulfamic acid added. The reaction mixture was stirred at 80 ^° C. for 17 hours. After cooling to room temperature, the reaction mixture was poured onto 300 ml of ethanol in which 1.3 g of NaOH had been dissolved. The resulting precipitate was filtered off and washed with ethanol. The after 2 days in the refrigerator from the filtrate further precipitated precipitate was also filtered off and combined with the first and dried. The solid was dissolved in water, the pH was adjusted to about 12 using NaOH, and the solution was ultrafiltered through a 1000 Dalton membrane to remove most of the inorganic salts. The residue was freeze-dried giving 0.7 g of a brown powder, which was designated B1. The TOC measurement of the dried residue gave 50.2% organic carbon.

Sulfation of the separated high-molecular lignin degradation product AHLA2: B2

1.52 g of the separated high-molecular lignin degradation product AHLA2 were dissolved in 20 ml of dry DMSO and treated with 0.22 g of sulfamic acid. The solution was slowly heated to 80 ⁰ C and stirred at this temperature for 3 hours. After cooling, the product was precipitated by pouring the reaction solution into 300 ml of ethanol in which 1.0 g of NaOH was dissolved, filtered off, washed with ethanol and dried. 1.9 g of dark brown solid were isolated. This solid was dissolved in water at pH 8.5. Some of the salts contained were separated by ultrafiltration using a 100 dalton membrane. The residue was concentrated on a rotary evaporator and freeze-dried. 0.97 g of a brown powder, designated B2, was obtained. The TOC measurement of the dry residue showed 10.0% organic carbon.

Comparative tests

For comparison purposes, the following reference reactions Ref.1, Ref.2, Ref.RGI and Ref.RG2 were carried out:

Sulfation of Lipnin 1: Ref.1 5 g of lignin 1 were dissolved in 30 ml of dry DMSO, 1.1 g

Sulfamic acid added and the solution stirred at 80 ⁰ C for 3 hours. After cooling to room temperature, it was poured onto 300 ml of ethanol in which 1.0 g of NaOH had been dissolved. The precipitated solid was filtered off and washed well with ethanol. After drying, the solid was dissolved in water and the solution ultrafiltered with a 1000 Dalton membrane to remove most of the inorganic salts. The residue became freeze-dried and labeled Ref.1. The TOC measurement of the dried residue showed 53.7% organic carbon.

• Sulfation of Lianin 2: Ref.2 5 g of lignin 2 were dissolved in 30 ml of dry DMSO at 35 ° C. 1.1 g

Sulfamic acid was added and the solution stirred at 80 ⁰ C for 3 hours. After cooling to room temperature was poured onto 300 ml of ethanol in which 1.0 g of NaOH was dissolved and the resulting solid was filtered off and washed well with ethanol. After drying, the solid was dissolved in water and ultrafiltered with a 100 dalton membrane to remove most of the inorganic salts. The residue was freeze-dried to give 6.1 g of brown powder, designated Ref.2. The TOC measurement of the dry residue showed 53.4% organic carbon.

• Sulfation of an unreacted reaction mixture RG1: Ref.RGI

The reaction mixture RG1 was concentrated on a rotary evaporator and freeze-dried. The 3.68 g solids contain 2.0 g of degraded lignin. This was dissolved in 40 ml of dry DMSO. After the addition of 0.44 g of sulfamic acid, the reaction mixture for 3 hours at 80 ⁰ C was stirred. After cooling, it was poured onto 600 ml of ethanol in which 2.0 g of NaOH were dissolved and the resulting precipitate was filtered off and washed with ethanol. The precipitate which precipitated from the filtrate after standing for 2 days in the refrigerator was also filtered off and combined with the first. The solid was dissolved in a little water, freeze-dried to give 3.9 g of powder, designated Ref.RGI. The TOC measurement gave 20.4% organic carbon.

• Sulfation of an unreacted reaction mixture RG2: Ref.RG2 The reaction mixture RG2 was dried on a rotary evaporator. The residue (2 g, equivalent to 1 g lignin degradation products) was dissolved in 20 ml of dry DMSO and treated with 0.22 g sulfamic acid. The solution was slowly heated to 80 ⁰ C and at this temperature 3 Hours stirred. After cooling, the product was precipitated by pouring the reaction solution into 300 ml of ethanol in which 1.0 g of NaOH was dissolved, and filtered off. The filtrate was stored in the refrigerator for 1 week and any precipitated solid also filtered and combined with the first. This solid was dissolved in water and the pH adjusted to 8.5. Some of the salts contained were separated by ultrafiltration using a 100 dalton membrane. The residue was concentrated on a rotary evaporator and freeze-dried. 0.96 g of a brown powder was obtained which was designated Ref.RG2. The TOC measurement of the dry residue gave 32.4% organic carbon.

Mannich reaction product of the separated high-molecular lignin degradation product AHLA3: B3

1.3 g of the separated high-molecular lignin degradation product AHLA3 (corresponding to 1.2 g degraded lignin) were dissolved in 4 ml of water and added 0.55 g of alanine and also dissolved. After adding 0.51 ml of a 36% formaldehyde solution, the pH was adjusted by adding

NaOH adjusted to approx. 9-10. Under nitrogen was heated to 85 ° C for 15 hours and it was obtained a Mannich base. The reaction conversion of alanine was 47% as determined by the decrease of alanine

Peaks in HPLC was calculated.

Mannich reaction product of the separated high molecular lignin degradation product AHLA4. B4 23.4 g of the separated high-molecular lignin degradation product

AHLA4 with a carbon content of 1.8% was largely dissolved in 18.8 ml of water. After adding 0.40 g of DL-alanine, the pH was adjusted to 9-10 by adding 100 mg of NaOH. 0.35 ml of a 36% formaldehyde solution was added, and after purging with nitrogen, the reaction mixture was stirred at 85 ° C for 16 hours to obtain a Mannich base. Verqleichsversuche

For comparison purposes, the following reference reactions Ref.3, Ref.4, Ref.RG3 and Ref.RG4 were carried out:

• Mannich reaction product of Lipnin 2: Ref.3. = Ref.4

10 g of lignin 2 were dissolved in 30 ml of water. 4.8 g of DL-alanine were added and also dissolved. By adding NaOH, the pH was adjusted to 9-10. 4.2 ml of a 36% formaldehyde solution were added, and the solution was heated to 85 ° C. under nitrogen for 16 hours under nitrogen to obtain a Mannich base. The reaction conversion of alanine was 40% as calculated from the decrease of the alanine peak in the HPLC.

Mannich reaction product of unseparated reaction mixture RG3. Ref.RG3

The reaction mixture RG3 was adjusted to pH 10 with NaOH, concentrated on a rotary evaporator and freeze-dried. 5.9 g of this powder with an organic carbon content of 28.7% (determined by TOC measurement) (corresponds to 3.4 g degraded lignin) were dissolved in 15 ml of water and 1.7 g of DL-alanine was added and also dissolved. The pH of the solution was adjusted to 9-10 by adding NaOH. After the addition of 1.5 ml of a 36% formaldehyde solution was heated with stirring for 16 hours under nitrogen to 85 ° C and it was obtained a Mannich base. The reaction conversion of alanine was 28%, as calculated from the decrease of the alanine peak in HPLC.

Mannich reaction product of unseparated reaction mixture RG4. Ref.RG4

The reaction mixture RG4 was brought to pH 10-10.5 with NaOH, concentrated by rotary evaporation and freeze-dried. 12.4 g of a powder were isolated. The TOC measurement has an organic carbon content of 3.6%. 12.3 g (corresponds to approx. 0.9 g mined Lignin) were mixed with 11.9 ml of water and partially dissolved. 0.48 g of DL-alanine was added and the pH of the solution was adjusted to 9-10 by addition of 250 mg of NaOH. 0.42 ml of a 36% formaldehyde solution was added and the mixture was stirred under nitrogen at 85 ° C for 16 hours to obtain a Mannich base.

Characterization degradation by SEC

For the characterization of lignin degradation, the weight average molecular weight M _{w was determined} via SEC (Size Exclusion Chromatography). The SEC analysis was carried out on a HPLC system (Alliance 2695, Waters) equipped with a column cascade from Polymer Standards Service GmbH (MCX 10 μm 1000A, MCX 10 μm 100000A + precolumn) and a UV detector (320 nm). As solvent and solvent for lignin and lignin degradation products, 0.01 molar aqueous sodium hydroxide solution was used. The calibration was carried out by means of 9 narrow polymer standards of sulfonated polystyrene in the molecular weight range 1'020'0OO Da to 3'420 Da. The weight average molecular weight was thus determined relative to sulfonated polystyrene.

The measured absorption signal of the UV detector (320 nm) was normalized in the chromatograms to the highest peak (corresponds to the unit (AU) 1). Plotted as X-axis is the elution volume (V _e ) or the corresponding molecular weight M _w (g / mol).

FIG. 1 shows the comparison of the SEC chromatograms of lignin 1 with the reaction mixture RG1.

FIG. 2 shows the comparison of the SEC chromatograms of lignin 2 with the reaction mixture RG2.

FIG. 3 shows the comparison of the SEC chromatograms of lignin 2 with the reaction mixture RG3. FIG. 4 shows the comparison of the SEC chromatograms of lignin 2 with the reaction mixture RG4. From the shift in the maximum molecular weight in the respective reaction mixture, it can be seen that a considerable reduction in the molecular weight has taken place during the degradation.

Characterization Separation by SEC

FIG. 5 shows by way of example the comparison of the SEC chromatograms of the chloroform extracts Ex-CI with the separated high-molecular lignin degradation product AHLA1 in Example 1.

FIG. 6 shows the comparison of the SEC chromatograms of the filtrate F3 and the separated high-molecular lignin degradation product AHLA3 of the reaction mixture RG3 separated by ultrafiltration in Example 3.

Both studies prove that the low molecular weight components were separated from the reaction mixture via extraction or ultrafiltration. FIG. 7 shows the comparison in Example 3 of the SEC chromatograms of the reaction mixture RG3 and of the high molecular weight lignin decomposition product AHLA3 separated by ultrafiltration from the reaction mixture RG3.

For the estimation of the monomer separation, the normalized SEC chromatograms as shown in FIG. 7 were used. For the determination of the separation of the monomers (i.e., having 1 benzene ring) (elution volume ~17.5ml), the monomer peak area of the reaction mixture RG3 (=, AM, RGI ") and AHLA3 (=, AM, AHLA3", respectively) were determined. The separation efficiency AE was calculated therefrom according to the following formula:

AE = (AM, RGI-AM, AHLÄ3) I AM, RGI The thus calculated separation efficiency AE for the monomers was found in

Example 3 is 98%.

For the dimers (i.e., having 2 benzene rings) (elution volume

~ 16.5ml) and trimers (i.e., having 3 benzene rings) (elution volume

~ 16ml), the respective peak areas were not easy to determine without complex deconvolution procedures. Therefore, for the sake of simplicity, when calculating AE instead of the peak areas, the respective peak heights at Peak maximum used. The corresponding calculation of the separation efficiency gave a value of 87% for the dimers and a value of 54% for the trimers.

The separated mono-, di- and trimers appear in the SEC chromatogram of the filtrate F3 (permeate). In addition, small amounts of degradation products larger than trimers are detectable in F3. The largest components found in the filtrate F3 have a molecular weight in the order of the cut-off of the membrane of 1000 daltons.

Usage tests in a hydraulic binder

The amounts of lignin or chemically modified degraded lignin indicated in Table 1 were weighed into the mixing water and dissolved in a 250 ml mixing vessel. In each case, 200 g of a mixture of 3 Swiss CEM I 42.5 cements (1: 1: 1 by weight) were sprinkled in each case. The cement paste thus formed was well mixed with a 2 cm diameter propeller stirrer at 2000 rpm for 2 minutes. An open measuring cylinder (50 mm diameter, 51 mm height) standing on a clean glass plate with a diameter of 30 cm was filled flat with the cement paste. The measuring cylinder is lifted so that the cement paste can flow out. The diameter of the cement paste cake formed is measured to an accuracy of 1 mm and recorded as flow grade {"FM2mιn"). The cement paste is filled back into the mixing vessel after the measurement and the measurement is repeated after 30 or 60 minutes from the addition of the mixing water the cement paste was mixed again for 15 seconds, and noted as a flow of the material after 30 minutes ("FM ₃₀ mm") or 60 minutes ("FM ₆₀ mm").

In the following tables, on the one hand, the amount of lignin used in each case as wt .-%, based on the cement, "m / Z" (calculated on the TOC).) Furthermore, the important in cement chemistry weight ratio of water to cement "W / Z ". Undegraded and non-chemically modified lignin 1 was used in Comparative Example R1-0. Undegraded and non-chemically modified lignin 2 was used in each case in Comparative Example R2-0 and R3-0 and R4-0.

When assessing the results in Table 1, it is important to consider that the same cement mix was used for one set of measurements at a time, so when comparing results from different series of measurements, slight variations due to different cement needs to be taken into account. This explains, for example, the deviations of the values of R3-0 compared to R4-0.

Table 1. Results of lignins or chemically modified lignin degradation products in cementitious binder. 1 nm = not measured It can be seen from the results in Table 1 that the examples Ex1, Ex2, Ex 3 or Ex4 which contain chemically modified lignin decomposition products B1, B2, B3 or B4 according to the invention have significantly better liquefaction (evident from the fluidity), when the corresponding undegraded and non-chemically modified lignins identify lignin 1 and lignin 2, respectively. Furthermore, the results also show that the examples which are based on chemically modified lignin degradation products B1, B2, B3 or B4 according to the invention have a significantly improved flow behavior than the comparative examples with the corresponding chemically modified degradation products not separated from the low molecular weight degradation products, or the chemical modified undegraded lignins.

The comparison of Example Ex2 with Comparative Examples R2-1 and R2-2 shows that with the additive B2 according to the invention, a comparable fluidity can already be achieved with just one third of the dosage as in the comparative additives Ref. 2 or Ref. R2G2 ,

Despite the fact that unreacted alanine is still present in the products in Mannichbase production, it is irrelevant to the flow behavior since a corresponding comparative test with a corresponding addition of alanine to the cement paste did not noticeably change the flow behavior.

Claims

claims

A process for the preparation of chemically modified lignin degradation products comprising the steps of:

(a) decomposing a starting material which is selected from the group consisting of lignin, lignin derivatives,

Lignin fragments, lignin-containing substances and mixtures thereof under acidic conditions in the presence of a liquid medium to low molecular weight and high molecular lignin degradation products, the low molecular weight Ligninabbauprodukte in their chemical structural formula have a maximum of three benzene ring units and the high molecular lignin degradation in their chemical structural formula more than three benzene ring units,

(B) at least substantial separation of the low molecular weight Ligninabbauprodukte to obtain a high molecular weight

Fraction and

(c) chemically modifying the high molecular weight lignin decomposition products contained in the high molecular weight fraction to chemically modified lignin decomposition products,

wherein the chemical modification of the high molecular lignin degradation products according to step (c) takes place only after the steps (a) and (b).

2. The method according to claim 1, characterized in that the degradation is carried out in the presence of at least one polyoxometalate.

3. The method according to claim 1, characterized in that the degradation in the presence of at least one acid, in particular in the presence of an acid having a pK _a i of less than 3, preferably less than 2.5, is performed.

4. The method according to any one of the preceding claims, characterized in that the degradation is carried out at a pH of 0.5 to 6, preferably at a pH of 1 to 3.

5. The method according to any one of the preceding claims, characterized in that the degradation is carried out at a temperature of 20 to 300 ⁰ C, preferably at a temperature of 100 to 200 ⁰ C.

6. The method according to any one of the preceding claims, characterized in that the degradation is carried out at an overpressure of 0 to 200 bar, preferably at an overpressure of 0 to 50 bar.

7. The method according to any one of the preceding claims, characterized in that the degradation in the presence of N ₂ , air or O ₂ , preferably O ₂ , is performed.

8. The method according to any one of the preceding claims, characterized in that the degradation takes place in a continuous process

9. The method according to any one of the preceding claims, characterized in that the degradation in the presence of at least one compound which prevents recombination of degradation products, in particular in the presence of a radical scavenger, which is preferably selected from the group consisting of alcohols, preferably methanol or ethanol; organic acids, preferably ascorbic acid; Phenols and stabilized free radicals is performed.

10. The method according to any one of the preceding claims, characterized in that the separation of the low molecular lignin degradation products in step (b) is such that in the chemically modified Ligninabbauprodukt after step (c) the proportion of the sum of low molecular lignin degradation products and chemically modified low molecular lignin degradation products less than 20 wt .-%, in particular less than 10 wt .-%, preferably less than 5 wt .-%, most preferably less than 1 wt .-%, is.

11. The method according to any one of the preceding claims, characterized in that the chemical modification of the high molecular lignin decomposition products comprises a reaction which is selected from the group consisting of addition, condensation and graft polymerization.

12. The method according to any one of the preceding claims, characterized in that the chemical modification of the high molecular lignin degradation products by reaction with at least one Reaktan-, which is selected from the group consisting of alcohols, carboxylic acids, hydroxycarboxylic acids, amino acids, acid chlorides,

Acid anhydrides, sulfonic acids, hydroxysulfonic acids, aminosulfonic acids, amidosulfonic acids, esters, lactones, lactams, alkyl halides, epoxides, amines, hydroxylamines, sulfuric acid, oleum, chlorosulfonic acid and olefinically unsaturated compounds.

13. The method according to any one of the preceding claims, characterized in that the chemical modification of the high molecular lignin degradation products is a radical graft polymerization with at least one olefinically unsaturated compound which is in particular selected from the group consisting of alkenes, dienes, olefinically unsaturated acids, olefinically unsaturated esters , olefinically unsaturated acid anhydrides, olefinically unsaturated amides, olefinically unsaturated ethers and olefinically unsaturated alcohols, preferably selected from the group consisting of acids or anhydrides or esters or amides of acrylic acid, methacrylic acid, maleic acid, fumaric acid, or itaconic acid,

Vinyl ethers, vinylsulfonic acids, vinyl esters, allyl alcohol and allyl ethers.

14. The method according to any one of the preceding claims, characterized in that the weight average molecular weight M _{w of} the high molecular lignin degradation products after step (a) is less than 80% of the molecular weight of the starting material used in step (a), preferably less than 60%.

15. Use of a chemically modified lignin degradation product prepared by a process according to any one of claims 1 to 14 as a dispersant.

16. A composition comprising at least one chemically modified lignin degradation product prepared by a process according to any one of claims 1 to 14 and at least one hydraulic binder.