CZ2012651A3 - Process for preparing polyurethane materials containing lignin and polyurethane material prepared in such a manner - Google Patents

Abstract

A process for preparing polyurethane materials by reacting a polyol with an isocyanate, with the addition of lignin to at least one reactant, is that the lignin particles are reduced to a size of nanometers to microns in the dispersing device and dispersed without the use of solvents. at least one component for preparing a one-component or two-component polyurethane material. The process according to the invention does not burden the environment and allows production without the use of organic solvents. Lignin-containing polyurethane materials prepared according to the invention have a homogeneous structure and modified properties. The solution's polyurethane casting resin has significantly increased electrical resistance and improved thermo-mechanical properties for use in the electrical industry.

Description

Process for the preparation of lignin-containing polyurethane materials, polyurethane material prepared in this way

Field of technology

The invention relates to the chemical industry, in particular to a process for the preparation of one-component or two-component polyurethane materials with the addition of lignin formed as a by-product in the production of cellulose.

State of the art

Lignin is an important building material for wood, which has the function of binding the long cellulose fibers and thus gives the wood its strength. In addition to cellulose, it is the second most common wood-forming substance. It is a high molecular weight amorphous substance that has a complex polyphenolic structure. The irregular structure of lignin is a mixture of physical and chemically heterogeneous substances. Lignin makes up about 20 to 35% of the weight of soft and hard wood, in a concentration of about 8% it is further contained, for example, in cereals. Lignin is isolated from wood biomass by two basic chemical delignification processes to form sulphate and alkaline kraft lignin. The sulphate type is prepared by pulping wood biomass at boiling in a solution of various sulfuric acid salts. The alkaline process consists in pulping the wood mass under boiling in a solution of sodium hydroxide and sodium sulphide. These processes yield sulfite and so-called "black liquor". A newer method of obtaining lignin from wood is the so-called "organosolv process", which is based on pulping by the action of acetic acid and formic acid and hydrogen peroxide, where the starting product is a dark brown solution of lignin in water. Depending on the delignification process used and the plant origin, these three types of lignin differ from each other mainly in molecular weight, number and type of functional groups.

Due to the fact that it is formed as a by-product in the production of pulp for the paper industry, lignin is understood more as a waste raw material. Although it is an easily available natural raw material, its industrial use is currently limited mainly due to its physicochemical properties. For example, the sulfite type of lignin is used to make dispersants, emulsifiers or phenolic adhesives.

Lignin shows low thermal stability and begins to decompose at a temperature of about 140 ° C. It is not very water resistant and its low molecular weight fractions are biodegradable. After drying in the raw state, lignin is in the form of a dark brown powder with a very specific odor.

Lignin is composed of carbon, hydrogen and oxygen and contains hydroxyl, methoxy, carbonyl and carboxyl groups in its structure. The primary and secondary hydroxyl groups of lignin can react with the isocyanate to form a urethane bond. By this addition reaction, lignin can be used in the preparation of polyurethane materials. In this case, lignin can be used as a natural renewable raw material replacing petrochemical polyols.

A major problem with the applicability of lignin in the preparation of polyurethane materials is the insolubility of lignin in polyols, which prevents the reaction of hydroxyl groups of lignin with isocyanate leading to the formation of a polymer network. The miscibility of lignin with the polyol component can be achieved either

by dissolving the lignin in a suitable organic solvent, or by chemical modification.

JP163182327 (A) discloses the preparation of lignin-containing polyurethanes, in which the lignin from the organosol process is used in the form of a solution in organic solvents such as tetrahydrofuran or dioxane. The main disadvantage of this process is the high toxicity of these solvents. Another disadvantage is the partial solubility of only the low molecular weight fractions, which make up about 30 to 40% of the lignin. The presence of high molecular weight fractions is the reason for the generally very poor solubility of lignin in organic solvents.

U.S. Pat. No.,017,474 (A) claims the preparation of a polycarboxy-oxyalkylene polyester-polyether polyol as a lignin-based liquid intermediate suitable for the production of polyurethane materials. It is a chemical modification of sulphite or alkaline, but also organosolv of lignin, where lignin is reacted in the first phase by a radical reaction with maleic anhydride. Subsequent hydrolysis opens the anhydride ring to form carboxyl groups, which are alkoxylated in the final step. Alkoxylation forms sections of linear polyether chains terminated by a primary or secondary hydroxyl group. In this way, a liquid lignin-based polyol capable of reacting with isocyanates to form polyurethanes is formed. However, this procedure has a disadvantage in the technological and financial demands of the chemical modification of lignin.

Another method of chemical modification to ensure the miscibility of lignin with the polyol component is disclosed in US2005 / 0014919A1. The solubility of the sulfite type lignin in the polyols is ensured by the partial neutralization of the sulfonate salts to the sulfonic acid. Neutralization can be performed

3:

by acid hydrolysis or by cation exchange cation exchange. The lignin bearing on the surface of the sulfonate acid group is miscible with the polyols and according to the patent can be used for the preparation of biodegradable foamed polyurethane compositions containing 1 to 40% of lignin. However, this effective chemical modification procedure is limited to the sulfite type of lignin.

The disadvantage of the current processes is either the insufficient dispersion of lignin in the polyols or the dispersion of the lignin in the polyols by means of toxic solvents. This fact limits the use of lignin for the production of polyurethane materials, or the production of polyurethane materials is toxic and represents a burden on the environment.

The essence of the invention

This object is achieved by a process for the preparation of polyurethane materials according to the invention. The preparation takes place by reacting the polyol with isocyanate, with the addition of lignin to at least one reactant. The present invention relates to lignin powder particles being reduced in size from nanometers to micrometers in a dispersing device and dispersed without the use of solvents in an isocyanate-terminated prepolymer in the preparation of one-component polyurethane materials or in a polyol reactant, and and / or isocyanate reactants in the preparation of two-component polyurethane materials.

The preparation of the dispersion takes place on dispersing devices characterized by a balanced grinding effect, shear stress and circulation of the dispersed phase in a continuous phase. These devices can be, for example, a bead mill, a colloid wet grinding mill with a cone-shaped rotor, an attritor, f, t Λ 4 »· it 99 _ χΛ» * 4 β · »i) t% ♦ * * ·« ΐΛ » »« »» T í · 4 «· 4 * 4« * ·· «*» · five-cylinder friction equipment and others. The particular type of dispersing device is selected according to the viscosity of the continuous phase, the particle size of the dispersed phase and the viscosity of the final dispersion. Sufficient grinding effect will allow efficient breaking of agglomerates and aggregates of lignin powder. Shear stress in the order of 10 -p,

10 ⁵ s ^-1 ensures sufficient exfoliation of lignin micro- and nanoparticles in the dispersion. For this purpose, a combination of the above stresses with sufficient circulation is necessary to ensure an even distribution of the dispersed lignin particles in the reactant. The use of optimal dispersing equipment allows the omission of volatile and often toxic organic solvents or technologically and economically demanding chemical pre-modifications of lignin. The particular type of dispersing device is selected according to the viscosity of the continuous phase, the particle size of the dispersed phase and the viscosity of the final dispersion. The size ^of the dispersed lignin particles ranges from 1,109 m to ^999,10,6 m.

In a preferred embodiment of the invention, at least one substance is added to the lignin dispersion in the prepolymer and / or in the polyol reactant and / or in the isocyanate reactant to modify the chemical or physical properties of the resulting dispersion, in particular the viscosity. This substance may be an additive or another part of a reactant.

Preferably, in preparing two-component polyurethane materials, a lignin dispersion is first formed in the first part of the polyol reactant, then the dispersion is homogenized by mixing with the second part of the polyol reactant, and the resulting mixture is reacted with the isocyanate reactant. However, it is also possible for the lignin particles to be dispersed throughout the volume of the polyol component, which is no longer diluted and directly reacts with the isocyanate component. Similar

The 5 'methods can be used to disperse lignin in the isocyanate component, or in the case of one-component polyurethanes in the prepolymer.

In a preferred embodiment, the polyol component comprises at least one substance or combination of substances containing two or more hydroxyl groups. These substances can be, for example, glycols, sugars, polyester polyols, polyether polyols, oil polyols and / or combinations thereof.

In another preferred embodiment, at least one additive or combination of additives is added to any component of the polyurethane system. The addition of the additive depends on the specific end application of the polyurethane material produced. Additives improve the processing properties or the properties of the final product. E.g. catalysts are necessary in certain processes to activate the reaction. It is preferred that the additive is at least one substance or combination of substances from the group: catalysts, blowing agents, defoamers, emulsifiers, dispersants, moisture absorbers, pigments, fillers, stabilizers, flame retardants.

Finally, it is preferred that the isocyanate component comprises at least one substance or combination of substances from the group of polyisocyanates, or isocyanates with blocked reactive groups, or monomeric isocyanates of the following types: toluylene diisocyanate (TDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanenyl diisocyanate (HMDI), ).

The invention further relates to a polyurethane material prepared as described above. The essence of the material lies in the fact that it contains lignin powder with a particle size reduced to microparticles and nanoparticles dispersed in the prepolymer

K. ; / / «Network» 4 * ’», »·» * »« terminated by at least one reactive isocyanate group for one-component polyurethane materials, or in a polyol reactant and / or isocyanate reactant for two-component polyurethane materials.

In a preferred embodiment, the polyurethane material is formed as a polyurethane casting resin with a lignin content in the range from 0.1 to 60% by weight. Lignin-containing polyurethane casting resin is characterized by increased electrical resistance and improved thermo-mechanical properties.

In another preferred embodiment, the polyurethane material is formed as a polyurethane coating composition with a lignin content in the range from 0.1 to 30% by weight.

In another preferred embodiment, the polyurethane material is formed as a polyurethane foam with a lignin content in the range from 0.1 to 10% by weight. This design includes soft, semi-rigid, hard, etc. polyurethane foams.

In a last preferred embodiment, the polyurethane material is formed as an adhesive or sealant with a pre-dried lignin content in the range from 0.1 to 60% by weight.

The advantages of the process for the preparation of the polyurethane materials according to the invention are that the preparation process comprises a solvent-free process for the high-efficiency dispersion of lignin in polyurethanes, which is technically easy to carry out and environmentally friendly. By modifying the operating conditions, this procedure can be used to prepare a wide range of polyurethane materials. The polyurethane materials according to the invention thus obtain a number of better physical ___ ly s * »*» »♦ * * *

O / * '\ V'A' \ «J» t β · i ♦ $ *. # * «,» · Properties such as: increased tensile strength, tensile modulus, toughness, electrical properties and names.

Examples of embodiments of the invention

It is to be understood that the specific embodiments of the invention described and illustrated below are presented by way of illustration and not by way of limitation. Those skilled in the art will find, or be able to ascertain using routine experimentation, more or less equivalents to the specific embodiments of the invention specifically described herein. These equivalents will also be included within the scope of the following claims.

To compare the production method and to improve the properties, the usual production methods and conventional polyurethane materials (Examples 1, 3 and 5) are given under odd numbers, and the processes and polyurethane materials according to the invention formed by them are given under even numbers (Examples 2, 4, 6 and 7). ).

Example 1 Synthesis of PU casting resin based on castor oil and cured MDI (standard 1)

The preparation of the PU casting resin consists in the reaction of the polyol component A and the isocyanate component B of the reaction mixture.

In the first phase, polyol component A, which is 126.1 g of castor oil (No. OH = 165 mg KOH / g), is fed to the reactor. A vacuum source is then connected to the reactor (oil pump) and component A is heated to 90 DEG C. with vigorous stirring. Distillation at a pressure of <0.1 mbar for about 1 hour reduces the water content of the polyol component A to < .05% by weight Po - C / Ί „<,; _e ja = -»

I «'· *« i * ”» »: 8 S *’

8> ’>

At the end of the distillation, component A is cooled to room temperature and, after the vacuum has been released, an inert gas, predried nitrogen or argon is introduced into the reactor.

In the second phase, 50.0 g of component B (NCO index = 105) are metered into component A with vigorous stirring and at room temperature. Isocyanate component B is Suprasec® 2642 (medium functional polymerized hexamethylene diisocyanate, NCO = 32.7 from Huntsman). A vacuum source (oil pump) is again connected to the reactor. The reaction mixture is homogenized at room temperature and under reduced pressure <0.1 mbar by vigorous stirring for about 30 minutes.

After homogenization is complete, the reactor is disconnected from the vacuum source. The reaction mixture is transferred from the reactor by casting into a pre-prepared metal mold measuring 0.2 x 15 x 20 cm.

The curing of the polyurethane mixture takes place in metal form at room temperature for 24 hours and then at 80 ° C for 1 hour, during which the polyurethane is crosslinked.

The properties of the PU elastomer (standard 1) are listed in Table 1.

Example 2 Synthesis of PU casting oil based on castor oil cured by MDI and containing 15 wt. lignin

In the first phase, a 50% dispersion of lignin organosolv in castor oil is prepared. 28.0 g of castor oil and 28.0 g of lignin are mixed in a 100 ml beaker. The mixture is then repeatedly dispersed ten times with high shear forces at 25 ° C in a size reduction shear device and

particle dispersion (Three Roll Mill EXAKT 80 E, by EXAKT technologies, Inc.). The prepared dispersion is a highly viscous paste without the presence of lignin aggregates.

In the second phase, polyol component A, which is a mixture of 56.0 g of castor oil and 56.0 g of a 50% dispersion of lignin in castor oil prepared in the first phase, is fed to the reactor. A vacuum source (oil pump) is then connected to the reactor and component A is heated to 90 DEG C. with vigorous stirring. Distillation at a pressure of <0.1 mbar for about 1 hour reduces the water content of the polyol component A to <0.05% by weight. At the end of the distillation, component A is cooled to room temperature and, after the vacuum has been released, an inert gas, predried nitrogen or argon is introduced into the reactor.

In the third phase, 50.0 g of component B (NCO index = 105) are metered into component A with vigorous stirring and at room temperature. The isocyanate component B is Suprasec® 2642 (medium functional polymerized hexamethylene diisocyanate, NCO = 32.7%, Huntsman). A vacuum source (oil pump) is again connected to the reactor. The reaction mixture is homogenized by vigorous stirring for about 30 minutes at room temperature and under reduced pressure <0.1 mbar.

After homogenization is complete, the reactor is disconnected from the vacuum source. The reaction mixture is transferred from the reactor by casting into a pre-prepared metal mold measuring 0.2 x 15 x 20 cm.

Curing of a polyurethane mixture with a content of 15% by weight. The lignin organosol takes place in metallic form at room temperature for 24 hours and then at 80 DEG C. for 1 hour, during which the polyurethane is crosslinked.

Id

Properties of PU elastomer with a content of 15% by weight. "The lignin organosolves are listed in Table 1.

Example 3 Synthesis of solvent-free PU coating based on castor oil and cured TDI (standard 2)

The preparation of the PU casting resin consists in the reaction of the polyol component A and the isocyanate component B of the reaction mixture.

In the first phase, polyol component A, which is 10.0 g of castor oil (No. OH = 165 mg KOH / g), is fed to the reactor. A vacuum source (oil pump) is then connected to the reactor and component A is heated to 90 with vigorous stirring; J2. Distillation at a pressure of <0.1 mbar for about 1 hour reduces the water content of the polyol component A to <0.05% by weight. inert gas, predried nitrogen or argon.

In the third phase, DABCO 33-LV® Catalyst (tertiary amine, Air Products) with a concentration of 0.1% is metered in to component A with vigorous stirring and at room temperature. wt. %: by weight of the reaction mixture. Subsequently, it is mixed with component g with 2.4 g of component B (NCO index = 105). The isocyanate component B is Scuranate® TDI 80 (toluylene diisocyanate, NCO = 48.2%, Perstorp).

After homogenization, the reaction mixture is stretched with a metal scraper with a slit of 200 [mu] m onto a glass and polypropylene separation pad.

; ’V * ~ β í; t j »*’ i J ‘♦ t '1'} * lít» ‘4 - A 4 í * ·

The curing of the polyurethane film takes place first by free drying at room temperature for 24 hours and then at 70 DEG C. for a further 24 hours. The film is cured at 120 DEG C. for 1 hour.

The properties of the high solids PU coating material (standard 2) are given in Table 2.

Example 4 Synthesis of a solvent-free PU coating material based on castor oil cured by TDI and containing 15% by weight. lignin

In the first phase, a 50% dispersion of lignin organosolv in castor oil is prepared. 25.0 g of castor oil and 25.0 g of lignin are mixed in a 100 ml beaker. The mixture is then repeatedly dispersed ten times with high shear forces at 25 ° C in a particle size reduction and dispersion shear device (Three Roll Mill EXAKT 80 E, EXAKT technologies, Inc.). The prepared dispersion is a highly viscous paste without the presence of lignin aggregates.

In the second phase, polyol component A, which is a mixture of 7.4 g of castor oil (No. OH = 165 mg KOH / g) and 2.6 g of a 50% dispersion of organosolv lignin in castor oil, is metered into the reactor. A vacuum source (oil pump) is then connected to the reactor and component A is heated to 90 DEG C. with vigorous stirring. Distillation at a pressure of <0.1 mbar for about 1 hour reduces the water content of the polyol component A to < At the end of the distillation, component A is cooled to room temperature and, after the vacuum has been released, an inert gas, predried nitrogen or argon is introduced into the reactor.

In the third phase, DABCO 33-LV® Catalyst (tertiary amine, Air Products) with a concentration of 0.1 wt.% Is metered in to component A with vigorous stirring and at room temperature. % by weight of the reaction mixture. Subsequently, it is mixed with component g with component 2.3 g (NCO index = 105). The isocyanate component B is Scuranate® TDI 80 (toluylene diisocyanate, NCO = 48.2%, Perstorp).

After homogenization, the reaction mixture is stretched with a metal scraper with a slit of 200 [mu] m onto a glass and polypropylene separation pad.

The curing of the polyurethane film takes place first by free drying at room temperature for 24 hours and then at 70 DEG C. for a further 24 hours. The film is cured at 120 DEG C. for 1 hour.

Properties of solvent-free PU paint with a content of 10% by weight. lignin are listed in Table 2.

Example 5 Synthesis of soft PU foam standard

The preparation of the soft PU foam consists in the reaction of the polyol component A and the isocyanate component B of the reaction mixture.

In the first phase, component A of the reaction mixture, which consists of 50.00 g of Slovaprop® G-48 S polyol (copolymer of propylene and ethylene oxide, No. OH = 48 mg KOH / g), is metered into a waxed paper crucible with a volume of 1 L ·. , Novácké chemical plants), 0.08 g Dabco® 33LV urethane bonding promoter (Air Products), 0.50 g Dabco® DC5906 silicone surfactant (Air Products), 0.10 g Kosmos® 29 tin crosslinking catalyst

13'.

-Ν '; i »

- ¹ and 4 * ^; ·? * «« «£ t« «(Evonik), and 1.78 g of distilled water used as blowing agents. The components of component A are homogenized for 30 s with vigorous stirring at 2000 rpm.

In the second phase, isocyanate component B, which is 23.48 g of Scuranate® TDI 80 (toluylene diisocyanate, NCO = 48.2%, by Perstorp), is metered in one portion to component A. The reaction mixture is then homogenized for 30 s at a stirrer speed of 2000 rpm.

After mixing, foaming occurs. The resulting polyurethane foam is then placed in an oven preheated to 100 ° C for 15 minutes. Curing of the prepared soft polyurethane foam takes place for 24b at a temperature of 25; C.

The properties of the soft polyurethane foam standard with a theoretical density of 30 kg / m ³ are given in Table 3.

Example 6 Synthesis of soft PU foam containing 1 wt. lignin

In the first phase, a 50% dispersion of lignin organosolv in Slovaprop® G-48 S polyol (copolymer of propylene and ethylene oxide, No. OH = 48 mg KOH / g, Novácké chemical plants) is prepared. 25.0 g of castor oil and 25.0 g of lignin are mixed in a 100 ml beaker. The mixture is then repeatedly dispersed ten times with high shear forces at 25 ° C in ^a particle size reduction and dispersion shear device (Three Roll Mill EXAKT 80 E, EXAKT technologies, Inc.). The prepared dispersion is a highly viscous paste without the presence of lignin aggregates.

* * ♦ ‘·» * * i 4 i * # i »·» »<* ·» * i? ·> * »Ό 5 •» · · * · ·? ♦ * · i * * * * · »

In the second phase, component A of the reaction mixture, which consists of 3.04 g of a 50% dispersion of lignin in a polyol, 48.48 g of a Slovaprop G-48 S polyol, 0.08 g of promoter, is metered into a 1 L waxed paper crucible. urethane bonding Dabco 33LV (Air Products), 0.50 g of silicone surfactant Dabco® DC5906 (Air Products), 0.10 g of tin catalyst Kosmos' 29 (Evonik), and 1.78 g of distilled water used as blowing agents . The components of component A are homogenized for 30 s with vigorous stirring at 2000 rpm.

In the third phase, isocyanate component B, which is 23.48 g of Scuranate® TDI 80 (toluylene diisocyanate, NCO = 48.2%, by Perstorp), is metered in one portion to component A. The reaction mixture is then homogenized for 30 s at a stirrer speed of 2000 rpm.

After mixing, foaming occurs. The resulting polyurethane foam is then placed in an oven preheated to 100 ° C for 15 minutes. Curing of the prepared soft polyurethane foam takes place for 24 hours at a temperature of 25 ° C.

Properties of soft polyurethane foam with a content of 1% by weight.

lignin and a theoretical density of 30 kg / m ³ are given in Table.p, 31

Example 7 Preparation of PU lignin-containing adhesive

100 g of pre-dried lignin (60 DEG C., 24 h) are mixed with a slow-running stirrer into a polyurethane prepolymer containing 12.6% of free isocyanate groups. The premix is then repeatedly dispersed on a five-cylinder friction device to form a perfectly smooth paste with a viscosity of 65 Pa.s. The prepared dispersion is used as a structural adhesive for bonding selected ΆΒ3 substrates. The shear strength of said adhesive on the pretreated surface of the plastic substrate is 6-8 MPa.

Table 1 Properties of polyurethane casting resins

Example 1 and d Rv [Ω] P [Om] O [MPa] ε [%] E [MPa] W [N / mm ² ] HD [Shore AND] Tg [° C] WA [%] 1 2.6e ^llJ 1, 9e ^lu 1.4 62 3.0 0.5 68 0 0.71 2 2.2 ⁱ² 1.9e ¹² 5.2 91 7.1 2.4 85 10 1.18

Rv ... electrical resistance p ... electrical resistivity o ... tensile strength ε ... elongation at break

E ... module

W ... transformation work

HD ... surface hardness (Durometer)

Tg ... glass transition temperature (DMA)

WA ... water absorption

Table 2 Properties of solvent-free polyurethane coatings

Example σ [MPa] ε [%] E [MPa] W [MPa] Tg [° C] 3 0.7 223 0.6 0.9 -16 4 3.3 135 3.6 2.2 -8

* 9 <· 4 and 4 »

4 4 »4 '· * *» ϊ · · ». · 9 «· 4 ·« · σ ... tensile strength

... elongated at break

E ... module

W ... transformation work

Tg ... glass transition temperature (DMA)

Table 3 Properties of soft polyurethane foams

Example pv [kg / m ³ ] IFD 25 [N] IFD 65 [N] Tg [° C] 5 31.33 9.5 16.8 -51 6 32.09 11.2 19.0 -50

pv .. bulk density IFD 25. .. the force needed to compress the sample to 25% of the original height IFD 65. .. the force needed to compress the specimen to 65% of the original height Tg .. glass transition temperature (DSC)

Industrial applicability

The process for the preparation of polyurethane materials according to the invention can be used for the industrial production and industrial applications of lignin-containing polyurethane materials in various fields of application, for example in electrical engineering, construction, the chemical and consumer industries.

Claims (12)

PATENT CLAIMS A process for the preparation of polyurethane materials by reacting a polyol with an isocyanate, with the addition of lignin to at least one reactant, characterized in that the lignin powder particles are reduced to a size in the order of nanometers to micrometers and dispersed without the use of solvents. to a prepolymer terminated by reactive isocyanate groups in the preparation of one-component polyurethane materials, or to a polyol reactant and / or an isocyanate reactant in the preparation of two-component polyurethane materials. Preparation process according to Claim 1, characterized in that at least one substance for adjusting the chemical or physical properties of the resulting dispersion, in particular the viscosity, is added to the lignin dispersion in the prepolymer and / or in the polyol reactant and / or in the isocyanate reactant. preferably an additive consisting of at least one substance or combination of substances from the group: catalysts, blowing agents, defoamers, emulsifiers, dispersants, absorber / moisture, pigments, fillers, stabilizers, flame retardants, or another part of a reactant. Process according to claim 2, characterized in that in the preparation of two-component polyurethane materials a lignin dispersion is first formed in the first part of the polyol reactant, then this dispersion is homogenized by mixing with the second part of the polyol reactant, and the resulting mixture is reacted with the isocyanate reactant. . Process according to Claim 2, characterized in that at least one additive consisting of at least one substance or combination of substances from the group: catalysts, blowing agents is added to the lignin dispersion in the prepolymer and / or in the polyol reactant and / or in the isocyanate reactant. agents, defoamers, emulsifiers, dispersants, moisture absorbers, pigments, fillers, stabilizers, flame retardants. Process according to at least one of Claims 1 to 4, characterized in that the polyol reactant comprises at least one substance or combination of substances containing two or more hydroxyl groups, from the group consisting of glycols, sugars, polyester polyols, polyether polyols, oil polyols and / or combinations thereof . Process according to at least one of Claims 1 to 5, characterized in that the isocyanate reactant comprises at least one substance or combination of substances from the group of polyisocyanates or monomeric isocyanates: toluylene diisocyanate (TDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HMDI) , diphenylmethane diisocyanate (HDI). , ΖλΖ; you Polyurethane material prepared by the process according to at least one of Claims 1 to 6, characterized in that it comprises lignin powder with a particle size reduced to microparticles and nanoparticles dispersed in a prepolymer terminated by reactive isocyanate groups for one-component polyurethane materials or in a polyol reactant. or an isocyanate reactant for two-component polyurethane materials. Polyurethane material according to Claim 7, characterized in that it is formed as a polyurethane casting resin with a lignin content in the range from 0.1 to 60% by weight. Polyurethane material according to Claim 7, characterized in that it is formed as a polyurethane coating material with a lignin content in the range from 0.1 to 30% by weight. Polyurethane material according to Claim 7, characterized in that it is formed as a polyurethane foam with a lignin content in the range from 0.1 to 10% by weight. Polyurethane material according to Claim 7, characterized in that it is formed as a polyurethane adhesive with a pre-dried lignin content in the range from 0.1 to 60% by weight. Polyurethane material according to Claim 7, characterized in that it is formed as a polyurethane sealant with a pre-dried lignin content in the range from 0.1 to 60% by weight.