Method for producing isocyanate-based stable dispersion containing derivatized polysaccharide

Abstract

The present invention relates to a method for making derivatized polysaccharides and to stable isocyanate-based dispersions containing the derivatized polysaccharides.

Description

Technical Field

[0001] The present invention relates to a method for producing a derivatized polysaccharide, a stable dispersion containing the derivatized polysaccharide in a dispersed state in an isocyanate-based liquid, and a product obtained using the stable dispersion.

Background Art

[0002] Cellulose is a fibrous and tough water-insoluble substance contained in the cell walls of plants. Cellulose is mainly a polysaccharide in which [β]-D-glucopyranose units are linked by 1→4 glycosidic bonds. Structurally, cellulose chains are arranged in microfibrils during crystallization, and intermolecular hydrogen bonds that rigidify the chains are formed at this time. Various crystalline polymorphs of cellulose are known.

[0003] To improve the (mechanical) properties of polyurethane materials, cellulose (and generally polysaccharides) is an attractive filler. However, cellulose has poor compatibility with isocyanate-based liquids, and it is extremely difficult to prepare a stable dispersion of cellulose materials in isocyanate-based liquids. Therefore, it is necessary to derivatize cellulose (polysaccharides) in advance.

[0004] The hydroxyl groups of cellulose are involved in many intramolecular and intermolecular hydrogen bonds and generally exhibit limited reactivity. Therefore, it is extremely difficult to chemically derivatize these hydroxyl groups. Even towards highly reactive molecules (such as isocyanates, etc.), these hydroxyl groups show little or no reactivity. Another drawback of these cellulose-based materials is that their melting points are high (usually higher than the thermal decomposition temperature), which limits the possibility of derivatization in the liquid phase.

[0005] Conventional approaches in the chemical derivatization of cellulose involve using chemically and / or physically harsh conditions (chemicals, temperature, pressure, pH, etc.) to dissolve or derivatize cellulose. This affects the bulk structure and related properties (such as crystallinity) of the substrate. These current solutions mainly focus on reducing or eliminating the hydrogen bonding patterns in cellulose-based substrates, as will be described later. Sometimes, this problem is simply ignored. In such cases, cellulose will act as an inert "filler".

[0006] One approach is to alkoxylate the substrate to enhance the solubility of the cellulose-based substrate and improve its compatibility with derivatizing agents. Alkoxylation affects crystallinity, leads to increased costs, and further involves environmental, health, and safety (EHS) risks.

[0007] Another possibility is to use monosaccharides, disaccharides, and / or oligosaccharides with various solubility characteristics. However, such use is limited in some applications when the bulk properties of the cellulose-based substrate are required (e.g., in composite materials).

[0008] Another approach is to break the hydrogen bonding network.

[0009] A commonly used method is to chemically delignify the cellulose-based substrate with sulfite or by alkali treatment (caustic soda, dilute NaOH) at high temperature in a pressure vessel (stepwise decomposition, molecular weight reduction, decrease in crystallinity). However, the aqueous media and residual moisture that are often bound in the hydrogen network are incompatible with isocyanate chemistry and cause side reactions. Furthermore, residues of the delignification medium (such as Na cations and / or K cations) may be released, which may cause side reactions with isocyanates (such as isocyanurate). Additionally, the stepwise decomposition of the structure leads to the deterioration of cellulose properties.

[0010] Furthermore, the hydrogen bond network can be partially or completely disrupted by using mechanical treatment (such as grinding or micronization), and the microfibrils are torn by mechanical energy to decompose the cellulose substrate. As a result, the molecular weight decreases and the amorphous content increases.

[0011] Alternatively, the cellulose-based substrate can be decomposed by using steam explosion under severe temperature / pressure conditions.

[0012] Patent Document 1 (EP2870181) discloses using a swelling agent (solvent) to derivatize a polysaccharide (such as cellulose) with a polyisocyanate (such as MDI) in order to activate the hydroxyl groups in the polysaccharide so that they can react with the polyisocyanate. However, this method has several drawbacks. In particular, after the derivatization process, it is necessary to precipitate, filter, wash, dry at high temperature, and finally disperse the derivatized polysaccharide in the target polyurethane prepolymer. Therefore, in this process, the production time of the derivatized polysaccharide becomes long and the production cost becomes high.

[0013] Therefore, there is still a need for a method for producing a derivatized polysaccharide that solves one or more of the above problems.

Prior Art Documents

Patent Documents

[0014]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0015] An object of the present invention is to provide an improved process for derivatizing a polysaccharide in order to produce a stable dispersion of the polysaccharide in an isocyanate-based liquid (such as an isocyanate prepolymer).

Means for Solving the Problems

[0016] Meaning of terms Unless otherwise specified, all terms used in the disclosure of the present invention, including technical and scientific terms, have the meanings commonly understood by those skilled in the technical field to which the present invention pertains. As further guidance, the meanings of the terms are explained below to better understand the teachings of the present invention.

[0017] (1) NCO value In the context of the present invention, the expression "NCO content" should be understood as the NCO value, which is defined as follows. That is, the isocyanate content (NCOv) of all isocyanate group-bearing compounds, also called NCO% or NCO content, is expressed in weight % and measured by a conventional NCO titration according to the DIN53185 standard. Briefly explained, isocyanate is reacted with an excess of di-n-butylamine to produce urea. Then the unreacted amine is titrated with standard nitric acid to the color change of the bromocresol green indicator or to the end point of potentiometric titration. The NCO% or NCO value is defined as the weight % of NCO groups present in the product. In the context of the present invention, the expression "NCO value" corresponds to the isocyanate value (also called isocyanate content or NCO content), which is the weight % of reactive isocyanate (NCO) groups in the isocyanate group-bearing compound and is determined using the following formula assuming the molecular weight of the NCO group is 42. "Isocyanate value" = weight % of NCO groups = 42 × functionality / molecular weight × 100 (%) (2) Isocyanate index or NCO index or index It is the ratio of NCO groups to isocyanate-reactive hydrogen atoms present in the formulation and is expressed as a percentage value as follows. [Moles of NCO] × 100 / [Moles of active hydrogen atoms] (%) That is, the NCO index represents the ratio of the isocyanate actually used in the formulation to the amount of isocyanate theoretically required to react with the amount of isocyanate-reactive hydrogen used in the formulation.

[0018] It should be noted that the isocyanate index used herein is considered from the perspective of the actual polymerization process for producing polyurethane materials, which includes an isocyanate component and an isocyanate-reactive component. Isocyanate groups consumed in preliminary steps for producing modified polyisocyanates (including isocyanate derivatives called prepolymers in the art), or active hydrogens consumed in preliminary steps (e.g., reacting with isocyanates to obtain modified polyols or modified polyamines), are not considered in the calculation of the isocyanate index.

[0019] (3) The expression "isocyanate-reactive hydrogen atoms" used herein to calculate the isocyanate index represents the total number of active hydrogen atoms of hydroxyl groups and amine groups present in the reactive composition. This means that in calculating the isocyanate index in the actual polymerization process, one hydroxyl group is regarded as containing one reactive hydrogen, and one primary amine group is regarded as containing one reactive hydrogen.

[0020] (4) In this specification, the term "average nominal hydroxyl functionality" (i.e., "functionality" for short) is used to indicate the number average functionality (the number of active hydrogen atoms per molecule) of a polyol or polyol composition, assuming that this is the number average functionality of the initiator used in the production (however, in reality, it is often slightly lower due to some terminal unsaturation).

[0021] (5) The terms "derivatized polysaccharide", "polysaccharide derivative", "modified polysaccharide", and "functionalized polysaccharide" as used herein are synonymous and used interchangeably to represent isocyanate-functionalized polysaccharides. The reaction product can be obtained by adding, reacting, contacting, or mixing various components.

[0022] (6) As used herein, the terms "prepolymer" and "isocyanate prepolymer" represent reactive intermediates between monomeric isocyanates and fully reacted polyurethane or polyurea polymers. A prepolymer is an isocyanate-terminated polymer containing polyurethane bonds (or urea bonds) and reactive NCO groups, and these reactive NCO groups further react with hydroxyl groups or amine groups to chain-extend the prepolymer and cause further cross-linking.

[0023] (7) The term "dispersion" represents a system in which distributed particles or granules of a substance are dispersed in a continuous phase of another substance. These two phases may be in the same state of matter or different states of matter. In the present invention, the derivatized polysaccharide may exist as a dispersion of derivatized polysaccharide particles in an isocyanate-based liquid in the isocyanate-based liquid.

[0024] (8) The term "stable dispersion" represents a dispersion in which the distributed particles or granules remain as individual particles over time. On the other hand, in an unstable dispersion, aggregation or precipitation of the particles or granules occurs over time.

[0025] (9) The term "shear thinning" represents the non-Newtonian behavior of a fluid whose viscosity decreases under shear strain. Shear thinning is considered synonymous with pseudoplastic behavior and is usually defined excluding time-dependent effects (such as thixotropy).

[0026] (10) The term "room temperature" as used in this specification refers to a temperature in the range of 15°C to 35°C, preferably a temperature in the range of 18°C to 25°C. Such temperatures include, for example, 18°C, 19°C, 20°C, 21°C, 22°C, 23°C, 24°C, and 25°C.

[0027] (11) "Average" means "number average" unless otherwise specified.

[0028] (12) The singular forms ("a", "an", and "the") as used in this specification include both singular and plural referents unless the context clearly dictates otherwise. For example, "an isocyanate group" means one isocyanate group or two or more isocyanate groups.

[0029] (13) The terms "comprising", "comprise", and "comprised of" as used in this specification are synonymous with "including", "includes", "containing", and "contains", are inclusive and without limitation, and do not exclude additional members, elements, or method steps not recited. Needless to say, the terms "comprising", "comprise", and "comprised of" as used in this specification include "consisting of", "consists", and "consists of".

[0030] (14) Throughout this application, the term "about" is used to indicate that a value includes the standard deviation or error with respect to the apparatus or method used to determine that value.

[0031] As used herein, “% by weight,” “wt%,” “weight percentage,” or “percentage by weight” are used interchangeably.

[0032] (16) The recitation of numerical ranges by endpoints includes all integers and, where appropriate, fractions included within that range (e.g., 1 to 5 includes, for example, 1, 2, 3, 4 when referring to the number of elements, and may also include 1.5, 2, 2.75, and 3.80 when referring to, for example, measured values). Further, the recitation of endpoints includes the endpoint values themselves (e.g., 1.0 to 5.0 includes both 1.0 and 5.0). Any numerical range recited herein is intended to include all subranges subsumed within that numerical range.

[0033] Detailed description In the following paragraphs, various aspects of the present invention will be described in more detail. Each aspect thus described can be combined with other aspects unless expressly stated to the contrary. In particular, any feature indicated as being preferred or advantageous can be combined with any other feature or function indicated as being preferred or advantageous.

[0034] References throughout this specification to “one embodiment” or “an embodiment” mean that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment (although they may). Further, as will be apparent to those of ordinary skill in the art from this disclosure, the particular features, structures, or characteristics can be combined in any suitable manner in one or more embodiments.

[0035] Furthermore, some embodiments described herein include some features included in other embodiments (but not other features), and combinations of features of different embodiments are considered to be within the scope of the present invention and to form different embodiments (which is self-evident to those skilled in the art). For example, in the appended claims, any of the claimed embodiments can be used in any combination.

[0036] Surprisingly, the inventors have found that one or more of the objects of the present invention are achieved by a one-pot multi-step process according to the present invention.

[0037] In a first step, at least one polysaccharide containing at least one polysaccharide compound is pre-reacted with an isocyanate-based liquid containing a specific amount of at least one isocyanate group-bearing compound under specific reaction conditions to enable derivatization of the polysaccharide compound so as to obtain a derivatized polysaccharide, and by improving the compatibility between the polysaccharide and the isocyanate-based liquid, a derivatized polysaccharide (also called a functionalized polysaccharide) is obtained. This first step is also called a derivatization step.

[0038] The derivatized polysaccharide according to the present invention contains a pendant-free isocyanate group, and by this isocyanate group, the polysaccharide derivative becomes compatible with the isocyanate-based liquid, and thus is extremely suitable for preparing a stable dispersion of the derivatized polysaccharide in the isocyanate-based liquid.

[0039] In a second step, the derivatized polysaccharide is diluted with an isocyanate-based liquid containing at least one isocyanate group-bearing compound under stirring conditions to prepare a dispersion of the derivatized polysaccharide in the isocyanate-based liquid. This second step is also called a dilution step.

[0040] In the third step, a composition containing at least one isocyanate-reactive compound is added to the diluted polysaccharide derivative obtained in step 2 at a high temperature for a predetermined time using specific stirring conditions, preferably 5 to 20% by weight, more preferably 8 to 15% by weight, and most preferably about 10% by weight of the derivatized polysaccharide based on the total weight of the dispersion, to obtain a stable dispersion of the derivatized polysaccharide in an isocyanate prepolymer having 6% to 25% NCO. This step is also called the dispersion step. The obtained stable dispersion can be further diluted with an isocyanate-based liquid if necessary.

[0041] The stable dispersion of the derivatized polysaccharide according to the present invention can be subsequently used in various applications by further reaction / derivatization with other isocyanate-reactive substances (substrates, specialty chemicals, polyurethane components, etc.).

[0042] Therefore, the present invention includes at least a first step (derivatization step) of derivatizing a polysaccharide to obtain a derivatized polysaccharide, a second step (dilution step) of further diluting the derivatized polysaccharide obtained in step 1 with an isocyanate-based liquid, and a third step (dispersion step) of preparing a stable dispersion of the derivatized polysaccharide in an isocyanate-based liquid of the polysaccharide. The stable dispersion of the derivatized polysaccharide is preferably a dispersion of the derivatized polysaccharide in an isocyanate prepolymer prepared by adding an isocyanate-reactive compound to the derivatized polysaccharide in step 3.

[0043] One of the advantages of the present invention is the fact that various processing steps for preparing a stable dispersion of a polysaccharide in an isocyanate-based liquid can be carried out in one reaction vessel (referred to as a "one-pot process").

[0044] Therefore, the process of the present invention for preparing a stable dispersion of a derivatized polysaccharide in an isocyanate-based liquid includes at least the following steps. (1) Supplying at least one polysaccharide containing at least one polysaccharide compound and having a water content of less than 6% by weight, preferably less than 4% by weight, more preferably less than 2% by weight based on the total weight of the polysaccharide, and an isocyanate-based liquid containing at least one isocyanate group-bearing compound, pre-reacting at least one polysaccharide with the isocyanate-based liquid, and mixing the resulting composition at room temperature Tr or, when Tm > Tr, at the melting temperature Tm of the isocyanate-based liquid for at least 10 minutes so that the molar ratio of the number of moles of isocyanate groups in the isocyanate group-bearing compound to the number of moles of OH groups derived from the polysaccharide compound is in the range of 0.3 to 0.7 to obtain a derivatized polysaccharide (derivatization step) (2) Diluting the derivatized polysaccharide obtained in step (1) with an isocyanate-based liquid containing at least one isocyanate group-bearing compound so that the amount of the derivatized polysaccharide in the isocyanate-based liquid is in the range of 10 to 33% by weight based on the total weight of [derivatized polysaccharide + isocyanate-based liquid] (dilution step) (3) Adding an isocyanate-reactive composition containing at least one isocyanate-reactive compound to the composition obtained after the dilution step at a high temperature higher than the melting temperature Tm of the isocyanate-based liquid and lower than 120°C to obtain a stable dispersion of the derivatized polysaccharide in the isocyanate-based liquid having an NCO value in the range of 6 to 25%, preferably 8 to 21%, more preferably 10 to 16% (dispersion step)

Embodiments for Carrying Out the Invention

[0045] In a preferred embodiment, the derivatization step, the dilution step, and the dispersion step are carried out in the same reaction vessel.

[0046] In a preferred embodiment, the isocyanate-based liquids used in the derivatization step and the dilution step may be the same or different.

[0047] According to some embodiments, both the dilution step and the derivatization step are carried out at room temperature Tr or, if Tm > Tr, at the melting temperature Tm of the isocyanate-based liquid.

[0048] In some embodiments of the present invention, the process of the present invention includes one or more additional steps such as further diluting with an isocyanate-based liquid and / or adding additives such as fillers, rheology modifiers, biocides, colorants, catalysts, plasticizers, adhesion promoters, defoamers, and stabilizers (not limited thereto).

[0049] Derivatization process According to a preferred embodiment, a derivatized polysaccharide is obtained after the derivatization step. The derivatized polysaccharide is a reaction product of at least one polysaccharide compound and at least one isocyanate group-bearing compound, where the molar ratio of [the number of moles of OH groups derived from the polysaccharide compound] to [the number of moles of the isocyanate group-bearing compound] is in the range of 0.3 to 0.7, preferably in the range of 0.3 to 0.6.

[0050] According to a preferred embodiment, at least one isocyanate group-bearing compound used in the derivatization step is a bifunctional isocyanate compound such as MDI, and during the derivatization step, 1 NCO equivalent reacts with 1 OH equivalent present in the polysaccharide compound of the polysaccharide. Since the number of hydroxyl groups available for reaction with the isocyanate group-bearing compound is limited, another NCO equivalent of the bifunctional isocyanate compound is likely to be available (in a free state) for further reaction.

[0051] According to some embodiments, the isocyanate-based liquid used in the derivatization step may be an isocyanate prepolymer having an NCO value of 5% or more, preferably in the range of 10% to 30%, more preferably in the range of 15% to 25%.

[0052] According to some embodiments, the mixing of at least one polysaccharide and an isocyanate-based liquid is carried out for at least 10 minutes, preferably for 10 to 70 minutes, more preferably for 20 to 50 minutes, and most preferably for 30 to 40 minutes.

[0053] According to some embodiments, the water content of the polysaccharide used in the derivatization step of the present invention needs to be less than 6% by weight, preferably less than 4% by weight, and more preferably less than 2% by weight. The polysaccharide may need to be pretreated to remove excess water. This pretreatment may include placing the polysaccharide in an oven at a temperature in the range of 70°C to 130°C for a predetermined time (e.g., 2 to 3 hours) to reduce the water content to 2% by weight or less (based on the total weight of the polysaccharide). Conditions such as 3 hours at about 80°C or 1 hour at about 120°C can be used to remove the excess water content. The removal of excess water in the polysaccharide is preferably carried out such that the crystallinity of the polysaccharide remains mostly unchanged.

[0054] In a preferred embodiment, at least one polysaccharide in the derivatization step is present in an amount in the range of 13 to 57% by weight based on the total weight of at least one polysaccharide and an isocyanate-based liquid combined. At least one polysaccharide in step (a) is preferably present in an amount in the range of 18 to 42% by weight based on the total weight of at least one polysaccharide and an isocyanate-based liquid combined, more preferably in the range of 25 to 35% by weight, and most preferably in the range of 20 to 30% by weight.

[0055] The derivatization step of the process of the present invention is preferably carried out at a temperature of less than 70°C, more preferably at a temperature of less than 60°C, even more preferably at a temperature of less than 50°C, and most preferably at a temperature of less than 43°C, at least higher than the melting temperature Tm of the isocyanate-based liquid. When the room temperature Tr is higher than the melting temperature Tm of the isocyanate-based liquid, the derivatization step is carried out at the room temperature Tr. When the melting temperature Tm of the isocyanate-based liquid is higher than Tr, the derivatization step is carried out at the melting temperature Tm of the isocyanate-based liquid.

[0056] In a preferred embodiment, the derivatization step of the process of the present invention is carried out for at least 30 minutes before the dilution step. The derivatization step includes mixing at least one polysaccharide and an isocyanate-based liquid, preferably for at least 10 minutes, more preferably for 10 to 70 minutes, even more preferably for 20 to 50 minutes, and most preferably for 30 to 40 minutes. The above time is the preferred time for a temperature of up to 50°C.

[0057] According to some embodiments, the polysaccharide derivative obtained by the process of the present invention includes a polysaccharide backbone and one or more pendant groups linked to the polysaccharide backbone via a carbamate bond -O-C(=O)-NH-. Such a carbamate bond can be formed by the reaction of a free isocyanate group -N=C=O and a hydroxyl group of the polysaccharide backbone.

[0058] According to some embodiments, the polysaccharide derivative obtained by the process of the present invention includes a polysaccharide backbone and one or more pendant groups linked to the polysaccharide backbone via a urea bond -NH-C(=O)-NH-. Such a urea bond can be formed by the reaction of a free isocyanate group -N=C=O and an amine group of the polysaccharide backbone.

[0059] According to some embodiments, the polysaccharide derivative obtained by the process of the present invention comprises a polysaccharide backbone and one or more pendant groups linked to the polysaccharide backbone via allophanate linkages -NH-C(=O)-N(-C(=O)-O-)-. Such allophanate linkages can be formed by the reaction of free isocyanate groups -N=C=O with urethane groups of the polysaccharide backbone.

[0060] According to some embodiments, the polysaccharide derivative obtained by the process of the present invention comprises a polysaccharide backbone and one or more pendant groups linked to the polysaccharide backbone via biuret linkages -NH-C(=O)-N(-C(=O)-NH-)-. Such biuret linkages can be formed by the reaction of free isocyanate groups -N=C=O with urea groups of the polysaccharide backbone.

[0061] According to some embodiments, the polysaccharide derivative obtained by the process of the present invention comprises a polysaccharide compound having on its backbone pendant groups linked to the polysaccharide backbone via carbamate linkages, urea linkages, allophanate linkages, and / or biuret linkages.

[0062] One or more pendant groups attached to the polysaccharide backbone contain at least one free isocyanate group -N=C=O, which can be used for further functionalization.

[0063] Dilution process In a preferred embodiment, the derivatized polysaccharide obtained in the derivatization step of the present invention is further diluted with an isocyanate-based liquid. The dilution step is preferably carried out by mixing the derivatized polysaccharide and the isocyanate-based liquid, preferably by stirring or shaking at a low speed, and preferably using a dynamic mixer or a static mixer at a speed of 200 to 500 rpm (e.g., about 250 rpm). Mixing is preferably carried out at a speed of less than 3000 rpm, more preferably at a speed of less than 2000 rpm, and even more preferably at a speed of less than 1000 rpm.

[0064] According to some embodiments, the isocyanate-based liquids used for the derivatization step and the dilution step may be the same or different.

[0065] According to some embodiments, the derivatized polysaccharide obtained in the derivatization step is diluted with an isocyanate-based liquid containing at least one isocyanate group-bearing compound such that the amount of the derivatized polysaccharide in the isocyanate-based liquid ranges from 10 to 33% by weight, preferably from 14 to 20% by weight, based on the total weight of [derivatized polysaccharide + isocyanate-based liquid].

[0066] According to some embodiments, the derivatized polysaccharide obtained in the derivatization step is diluted with an isocyanate-based liquid containing at least one isocyanate group-bearing compound such that the NCO value of the diluted composition ranges from 14 to 50%, preferably from 22 to 30%, more preferably from 23 to 28%.

[0067] Dispersion process According to some embodiments, the dispersion step is performed by mixing the composition obtained in the dilution step with at least one isocyanate-reactive compound and optionally at least one catalyst. Any other step can also be performed in the presence of a catalyst.

[0068] According to a preferred embodiment, the isocyanate-reactive compound used in the dispersion step is selected from isocyanate-reactive compounds having isocyanate-reactive hydrogen atoms (such as amines and polyols). Generally, the isocyanate-reactive compound is selected from hydroxyl-terminated polyethers (polyether polyols), hydroxyl-terminated polycarbonates, hydroxyl-terminated polyesters (polyester polyols), or mixtures thereof.

[0069] According to some embodiments, the dispersion step is carried out at a high temperature that is higher than the melting temperature Tm of the isocyanate-based liquid used in the dilution step and less than 120°C. The temperature is preferably above the melting temperature Tm of the isocyanate-based liquid and less than 120°C, more preferably in the range of 50°C to 100°C, and most preferably in the range of 50°C to 85°C (varies depending on the type of isocyanate group-bearing compound used). When the isocyanate-based liquid is MDI, a temperature in the range of 70°C to 85°C (preferably about 80°C) is preferred.

[0070] According to some embodiments, before adding the isocyanate-reactive compound to the reaction vessel, the reaction vessel is heated to a temperature suitable for prepolymerization of the isocyanate group-bearing compound in the isocyanate-based liquid and the added isocyanate-reactive compound. This may include heating the diluted polysaccharide derivative to 50°C to 60°C, then gradually adding the isocyanate-reactive compound into the reaction vessel, adjusting the addition rate so that the temperature does not exceed 120°C, and cooling the reaction vessel as necessary.

[0071] According to some embodiments, the dispersion step is carried out by adding an isocyanate-reactive composition containing at least one isocyanate-reactive compound to the composition obtained after the dilution step to obtain a stable dispersion of derivatized polysaccharide in an isocyanate-based liquid having an NCO value in the range of 6 to 25%, preferably 8 to 21%, more preferably 10 to 16%. The isocyanate-based liquid of the stable dispersion thus obtained can also be referred to as an isocyanate prepolymer having unreacted free NCO groups.

[0072] According to some embodiments, the dispersion step is carried out by adding an isocyanate-reactive composition containing at least one isocyanate-reactive compound to the composition obtained after the dilution step at a high temperature for a predetermined time and then mixing for at least 60 minutes, preferably at least 90 minutes, more preferably at least 120 minutes.

[0073] According to some embodiments, the catalyst used in the dispersion step can be selected from organometallic catalysts.

[0074] According to some embodiments, the catalyst may be present in an amount of at least 10 ppm (e.g., at least 0.01 wt% or at least 0.20 wt%) based on the total weight of the diluted polysaccharide derivative (the mixture obtained after the dilution step).

[0075] In some embodiments, the catalyst may be present in an amount of at most 5 wt% based on the total weight of the mixture obtained after the dilution step.

[0076] According to some embodiments, the stable dispersion containing the derivatized polysaccharide of the present invention is an isocyanate prepolymer having shear-thinning viscosity behavior and containing the dispersed derivatized polysaccharide.

[0077] According to a preferred embodiment, the stable dispersion containing the derivatized polysaccharide of the present invention is an isocyanate prepolymer containing preferably 5 to 20 wt%, more preferably 8 to 15 wt%, and most preferably about 10 wt% of the dispersed derivatized polysaccharide based on the total weight of the stable dispersion. This dispersion can be further diluted with an isocyanate-based liquid as needed to lower the weight percentage of the derivatized polysaccharide.

[0078] The stable dispersion of the derivatized polysaccharide of the present invention is extremely suitable for producing composite materials, adhesives, paints, fillers, fibers, packaging materials, films, foams, fabrics, sealants, rheology modifiers, paints, and chromatography packing materials (solid phase), etc.

[0079] The stable dispersion containing the derivatized polysaccharide of the present invention (isocyanate prepolymer containing a dispersed polysaccharide derivative) is a dispersion that exhibits improved strength when used for adhesion to metals, plastics, and wood. When applied to adhere wood substrates and / or plastic substrates to each other, these dispersions cause 80 - 100% substrate failure. The stable dispersion containing the derivatized polysaccharide of the present invention (isocyanate prepolymer containing a dispersed polysaccharide derivative) is a dispersion that exhibits improved strength when used for adhesion to metals, plastics, and wood. When applied to adhere wood substrates and / or plastic substrates to each other, these dispersions cause faster curing.

[0080] Polysaccharides suitable for use according to the present invention As used herein, "polysaccharide" refers to a compound containing at least five monosaccharide monomer subunits linked by glycosidic bonds.

[0081] Preferably, at least one polysaccharide has a degree of polymerization of at least 10, more preferably at least 20, even more preferably at least 50, such as at least 100, such as at least 150, such as at least 200, such as at least 500.

[0082] At least one polysaccharide may be a natural substance or a synthetic substance. At least one polysaccharide may be crude or purified. At least one polysaccharide may be as obtained, (partially) pre-derivatized, or modified. At least one polysaccharide may be linear, branched, or cyclic. At least one polysaccharide may be a homopolysaccharide (also called a homoglycan) or a heteropolysaccharide (also called a heteroglycan).

[0083] At least one polysaccharide is hexose-based (i.e., at least one polysaccharide contains at least one hexose subunit). Preferably, at least one polysaccharide contains at least 50% by weight of hexose subunits, more preferably at least 75% by weight of hexose subunits, and even more preferably at least 90% by weight of hexose subunits, based on the total weight of the polysaccharide. At least one polysaccharide is preferably based on cyclic hexose.

[0084] In a preferred embodiment, at least one polysaccharide contains at least one glucose subunit. Preferably, at least one polysaccharide contains at least 50% by weight of glucose subunits, more preferably at least 75% by weight of glucose subunits, and even more preferably at least 90% by weight of glucose subunits, based on the total weight of the polysaccharide. The glucose subunit may be a modified glucose subunit (e.g., an amino glucose subunit having a substituent at the C2 or C3 position).

[0085] In some embodiments, at least one polysaccharide is selected from the group consisting of cellulosic compounds; starches (such as amylose, amylopectin, or mixtures thereof); agarose; alginic acid; alguronic acid; α-glucan; amylopectin; amylose; arabinoxylan; β-glucan; carlose; capsulan; carrageenan; cellodextrin; cellulins; chitin; chitosan; chrysolaminarin; curdlan; cyclodextrin; DEAE-sepharose; dextran; dextrin; α-cyclodextrin; ficoll; fructan; fucoidan; galactoglucomannan; galactomannan; gellan gum; glucan; glucomannan; glycocalyx; glycogen; hemicellulose; hypromellose; icodextrin; kefiran; laminarin; lentinan; levan; lichenin; maltodextrin; mixed-linkage glucan; mucus; natural gums; oxidized cellulose; paramylon; pectic acid; pectin; pentastarch; pullulan; polydextrose; polysaccharide peptides; porphyran; pullulan; schizophyllan; sepharose; sinistrin; schizophyllan; sugammadex; welan gum; xanthan gum; xylan; xyloglucan; dimosan; glycosaminoglycans, chondroitin, chondroitin sulfate, dermatan sulfate, heparan sulfate, heparin, heparinoid, hyaluronan, keratan sulfate, restylene, sodium hyaluronate, and slodexide, and mixtures thereof. In preferred embodiments, at least one polysaccharide is selected from the group consisting of cellulosic compounds and starch.

[0086] In certain embodiments, at least one polysaccharide is a starch selected from the group consisting of corn starch, amylose, acetylated distarch adipate, amylomaize, amylopectin, cyclodextrin, dextrin, dialdehyde starch, erythronium japonicum, high fructose corn syrup, hydrogenated starch hydrolysate, hydroxyethyl starch, hydroxypropyl distarch phosphate, maltitol, maltodextrin, maltose, pentastarch, phosphorylated distarch phosphate, potato starch, starch, waxy corn, waxy potato starch, and mixtures thereof.

[0087] In certain embodiments, at least one polysaccharide is a cellulose-based compound selected from the group consisting of cellulose, nanocellulose, art silk, bacterial cellulose, bamboo fiber, carboxymethyl cellulose, cellodextrin, cellophane, celluloid, cellulose acetate, cellulose acetate phthalate, triacetate cellulose, cellulosome, cotton, croscarmellose sodium, crystalate, cyethylaminoethyl cellulose, dissolved pulp, ethulose, ethyl cellulose, fique, hydroxyethyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl cellulose, hypromellose, lyocell, mercerized pulp, methyl cellulose, microbial cellulose, microcrystalline cellulose, modal (fabric), nitrocellulose, parksin, perloid, pulp, paper, rayon, sodium cellulose phosphate, supima, viscose, vulcanized fiber, wood fiber, and mixtures thereof.

[0088] In a preferred embodiment, the polysaccharide is cellulose. As used herein, "cellulose" refers to a polysaccharide containing a linear chain of several hundred to over ten thousand β(1→4)-linked D-glucose units.

[0089] Isocyanate group-bearing compounds suitable for use according to the present invention As used herein, the "isocyanate group-bearing compound" includes any compound containing at least one isocyanate group -N=C=O, where the isocyanate group may be a terminal group. Preferably, the isocyanate group is a terminal group. The isocyanate group-bearing compound is preferably a polyisocyanate compound. Suitable polyisocyanates used are generally of the type R-(NCO) x (where x is at least 1, preferably at least 2, and R is an aromatic group or an aromatic / aliphatic mixed group) and may be an arylaliphatic polyisocyanate and / or an aromatic polyisocyanate. Examples of R include diphenylmethane, toluene, or groups that give similar polyisocyanates, etc.

[0090] In a preferred embodiment, the isocyanate group-bearing compound is a polyisocyanate. By partial surface cross-linking with the polyisocyanate (intra-chain and inter-chain cross-linking between cellulose chains), most of the cellulose substrate can be protected from further derivatization. In this way, the crystalline and rigid properties of the cellulose backbone can be retained for further applications (such as composite materials) where the bulk properties of the cellulosic material are required. The free isocyanate groups can further be used for further functionalization or derivatization. The free isocyanate groups of the polyisocyanate may further trimerize to form isocyanurate groups.

[0091] In a preferred embodiment, at least one isocyanate group-bearing compound is methylene diphenyl diisocyanate in the form of 2,4'-isomer, 2,2'-isomer, 4,4'-isomer, and mixtures thereof, a mixture of methylene diphenyl diisocyanate and its oligomers, urethane groups, isocyanurate groups, allophanate groups, biuret groups, uretonimine groups, uretdione groups, and / or their derivatives having iminooxadiazinedione groups, and mixtures of the above substances; toluene diisocyanate and mixtures of their isomers; tetramethylxylylene diisocyanate; 1,5-naphthalene diisocyanate; p-phenylene diisocyanate; tolidine diisocyanate; or mixtures of these organic polyisocyanates, mixtures of one or more of these organic polyisocyanates and methylene diphenyl diisocyanate in the form of 2,4'-isomer, 2,2'-isomer, 4,4'-isomer, and mixtures thereof, a mixture of methylene diphenyl diisocyanate and its oligomers; a polyisocyanate selected from the group consisting of.

[0092] In one embodiment, at least one isocyanate group-bearing compound is a reaction product of a polyisocyanate (e.g., a polyisocyanate as shown above) and a component containing isocyanate-reactive hydrogen atoms that forms a high molecular weight polyisocyanate (so-called prepolymer). The prepolymer can usually be produced by reacting an isocyanate-reactive component, which is a component containing isocyanate-reactive hydrogen atoms [e.g., hydroxyl-terminated polyethers (polyether polyols), hydroxyl-terminated polycarbonates, or mixtures thereof, and hydroxyl-terminated polyesters (polyester polyols), etc.] with a polyisocyanate.

[0093] In a preferred embodiment, the isocyanate group-bearing compound comprises MDI. MDI is preferably in the form of the 2,4'-isomer, 2,2'-isomer, 4,4'-isomer, and mixtures thereof, or in the form of a mixture of diphenylmethane diisocyanate (MDI) and their oligomers. In some embodiments, MDI is in the form of the 2,4'-isomer, 2,2'-isomer, 4,4'-isomer, and mixtures thereof, or in the form of a mixture of these diphenylmethane diisocyanates (MDI) and their oligomers. In some embodiments, MDI is in the form of the 2,4'-isomer, or in the form of a mixture of the 2,4'-isomer and their oligomers. When using 2,4'-MDI-containing isocyanate, the crosslinking between two cellulose chains is inhibited to some extent compared to using pure 4,4'-MDI, and as a result, more crosslinking occurs. Therefore, by selecting the type of the first MDI, the amount of pendant isocyanate and the degree of crosslinking can be adjusted. At least one isocyanate is preferably a mixture of 2,4'-MDI and 4,4'-MDI. In some embodiments, the polyisocyanate comprises a high molecular weight polyisocyanate. In some embodiments, the polyisocyanate comprises a high functionality high molecular weight polyisocyanate having a functionality of at least 2.5 (preferably at least 2.7). As used herein, "functionality" refers to the average number of isocyanate groups per molecule averaged over the statistically relevant number of molecules present in the isocyanate.

[0094] In some embodiments, at least one isocyanate group-bearing compound comprises high molecular weight methylene diphenyl diisocyanate (MDI).

[0095] High molecular weight methylene diphenyl diisocyanate may be any mixture of pure MDI (2,4'-, 2,2'-, and 4,4'-methylene diphenyl diisocyanate) and their higher homologues.

[0096] Isocyanate-reactive compounds suitable for use according to the present invention Isocyanate-reactive compounds suitable for making isocyanate prepolymers and / or stable dispersions of derivatized polysaccharides according to the present invention are compounds containing isocyanate-reactive hydrogen atoms (such as amines and polyols). Generally, the isocyanate-reactive compounds are hydroxyl-terminated polyethers (polyether polyols), hydroxyl-terminated polycarbonates, hydroxyl-terminated polyesters (polyester polyols), or mixtures thereof. Examples of suitable polyether polyols include diols or polyols having a total of 2 to 15 carbon atoms [preferably, ethers containing alkylene oxides having 2 to 6 carbon atoms (generally ethylene oxide, propylene oxide, or mixtures thereof) and reacting with, preferably, alkyldiols or alkyl glycols], and preferably polyether polyols having at least 2 (e.g., 2 to 6) functional values, but are not limited thereto. Hydroxyl-functional polyethers can be produced by first reacting propylene glycol with propylene oxide and then reacting with ethylene oxide. The primary hydroxyl groups resulting from ethylene oxide are more reactive than secondary hydroxyl groups and are thus preferred. Useful commercially available polyether polyols include poly(ethylene glycol) containing ethylene oxide reacted with ethylene glycol, poly(propylene glycol) containing propylene oxide reacted with propylene glycol, and poly(tetramethylene glycol) (PTMG) containing water reacted with tetrahydrofuran (THF). The polyether polyol may further contain polyamide adducts of alkylene oxides, for example, ethylenediamine adducts containing reaction products of ethylenediamine and propylene oxide, diethylenetriamine adducts containing reaction products of diethylenetriamine and propylene oxide, and similar polyamide-type polyether polyols. In the present invention, copolyethers can also be used. Representative copolyethers include reaction products of glycerol and ethylene oxide, or reaction products of glycerol and propylene oxide.The various polyether intermediates generally have a number average molecular weight (Mn) of from about 200 to about 10,000, desirably from about 200 to about 5,000, preferably from about 200 to about 3,000, as measured by analysis of the terminal functional groups.

[0097] According to some embodiments, the isocyanate-reactive compound is a polyether polyol such as a terminal EO polyether polyol. Suitable terminal EO polyether polyols include polyether polyols having the structure of I-[R-(CH2CH2O) p H] x wherein x is an integer of 1 or more, p is a number varying between 1 and 100, I is an initiator, R represents a series of epoxides, and the (CH2CH2O) p H group is bonded to R via an ether bond. The initiator I may be an alcohol, an amine, a polyhydric alcohol, a polyamine, or a component containing one or more alcohol groups and one or more amine groups.

[0098] Catalysts suitable for use in the process according to the present invention According to some embodiments, a catalyst can be used in the dispersion step to catalyze the prepolymerization of the isocyanate group-bearing compound and the isocyanate-reactive compound to produce an isocyanate prepolymer. Any catalyst known to those skilled in the art for producing polyurethane materials can be used.

[0099] According to some embodiments, the catalyst may be an organometallic catalyst. In these embodiments, the catalyst comprises an element selected from the group consisting of tin, iron, lead, bismuth, mercury, titanium, hafnium, zirconium, and combinations thereof. In certain embodiments, the catalyst comprises a tin catalyst. Suitable tin catalysts suitable for the purposes of the present invention can be selected from tin(II) salts of organic carboxylic acids [such as tin(II) acetate, tin(II) octoate, tin(II) ethylhexanoate, and tin(II) laurate]. In one embodiment, the organometallic catalyst comprises dibutyltin dilaurate, which is a dialkyltin(II) salt of an organic carboxylic acid. The organometallic catalyst may further comprise other dialkyltin(II) salts of organic carboxylic acids such as dibutyltin diacetate, dibutyltin maleate, and dioctyltin diacetate. Specific examples of suitable organometallic catalysts suitable for the purposes of the present invention (such as dibutyltin dilaurate) are commercially available under the trade name DABCO® from Air Products and Chemicals, Inc. Preferred catalysts according to the present invention are dibutyltin dilaurate, dibutyltin diacetate, dioctyltin diacetate, and tin octoate.

[0100] Examples of other suitable catalysts include iron(II) chloride; zinc chloride; lead octoate; tris(dialkylaminoalkyl)-s-hexahydrotriazines including tris(N,N-dimethylaminopropyl)-s-hexahydrotriazine; tetraalkylammonium hydroxides including tetramethylammonium hydroxide; alkali metal hydroxides including sodium hydroxide and potassium hydroxide; alkali metal alkoxides including sodium methoxide and potassium isopropoxide; alkali metal salts of long-chain fatty acids having 10 to 20 carbon atoms and / or OH side groups; triethylamine; N,N,N',N'-tetramethylethylenediamine; N,N-dimethylaminopropylamine; N,N,N',N',N''-pentamethyldipropylenetriamine; tris(dimethylaminopropyl)amine; N,N-dimethylpiperazine; tetramethylimino-bis(propylamine); dimethylbenzylamine; trimethylamine; triethanolamine; N,N-diethylethanolamine; N-methylpyrrolidone; N-methylmorpholine; N-ethylmorpholine; bis(2-dimethylamino-ethyl)ether; N,N-dimethylcyclohexylamine (DMCHA); N,N,N',N',N''-pentamethyldiethylenetriamine; 1,2-dimethylimidazole; 3-(dimethylamino)propylimidazole; N,N,N-dimethylaminopropylhexahydrotriazine; potassium acetate; N,N,N-trimethylisopropylamine / formate; and combinations thereof; and can be selected from the group comprising.

[0101] The stabilized dispersions comprising the derivatized polysaccharides according to the invention and the derivatized polysaccharides obtained by the process of the invention can be used in packaging materials, films, foams, composite materials, adhesives, paints, fabrics, sealants, rheology modifiers, paints, and chromatography packing materials (solid phase), etc.

[0102] In a preferred embodiment, the derivatized polysaccharide of the present invention is in the form of granules as such or as present in the stable dispersion of the present invention. At this time, the granules have a particle size distribution with a D50 of at most 1.0 mm, preferably at most 200 microns (μm), and most preferably at most 30 microns (μm), where D50 is defined as the particle size at which 50% by weight of the particles have a size smaller than 30 microns (μm). For example, D50 (and / or D90 or D95) can be measured by sieving, BET surface measurement, or laser diffraction analysis, for example, in accordance with ISO standard 13320:2009.

[0103] In a preferred embodiment, the derivatized polysaccharide of the present invention is in the form of a thread or fiber as such or as present in the stable dispersion of the present invention, and has a linear mass density of at most 2000 denier, preferably 5 - 2000 denier, preferably 5 - 500 denier, and in the most preferred embodiment, 5 - 200 denier.

[0104] In a preferred embodiment, the derivatized polysaccharide of the present invention is in the form of a fabric or cloth as such or as present in the stable dispersion of the present invention, and at this time, the fabric or cloth may or may not be woven. The crystallinity index (CI) of at least one polysaccharide may be at least 10%, for example, at least 20%, for example, at least 30%, for example, at least 40%, for example, at least 50%, for example, at least 60%, for example, at least 70%.

Examples

[0105] The examples described below illustrate the processes and properties of the polysaccharide derivatives according to the embodiments of the present invention. Unless otherwise specified, all parts and percentage values throughout the following examples and this specification are by weight parts and weight %, respectively.

[0106] Chemical substances SUPRASEC (registered trademark) 2020 (S2020) is a uretonimine-modified MDI with an NCO value of 29.5% and a functionality (f) of 2.11, which is commercially available from Huntsman and was used as it was.

[0107] SUPRASEC 2144 (S2144) is an MDI prepolymer with an NCO value of 15.2%.

[0108] SUPRASEC (registered trademark) 3050 (S3050) is a mixture of 4,4'-MDI and 2,4'-MDI with an NCO value of 33.6% and a functionality (f) of 2, which is commercially available from Huntsman and was used as it was.

[0109] ARBOCELL (registered trademark) BE600 / 30 is a high-purity white α-cellulose fiber with an average fiber length of 30 μm, which is commercially available from J. Rettenmair & Sohne (JRS) and was used after drying.

[0110] Avicel (registered trademark) is microcrystalline cellulose with an average fiber length of 50 μm and was used after drying.

[0111] DALTOCELL (registered trademark) F456 (F456) is a polyether polyol with a hydroxyl value of 56 mg KOH / g and an f of 2, which is commercially available from Huntsman and was used after drying.

[0112] Acetonitrile (AN) of HPLC grade, commercially available from Rathburn, was used as it was.

[0113] DMSO (dimethyl sulfoxide) of anhydrous grade, commercially available from Sigma-Aldrich, was used as it was.

[0114] Methods The following method was used in the examples.

[0115] The urethane bond stretching mode and the isocyanate bond stretching mode were identified using FT-IR analysis (ATR mode).

[0116] Example 1 according to the present invention (MDI-derivatized cellulose-containing prepolymer) α-Cellulose (ARBOCEL BE600-30) was dried at 80 °C for 3 hours under reduced pressure to reduce the moisture content in the cellulose from 6.6 wt% to 2 wt% (based on the total weight of the cellulose). 100 g of the dried cellulose was weighed into a reaction flask, and subsequently 280 g of SUPRASEC2020 (S2020) was added to the reaction flask under a nitrogen atmosphere. This slurry was stirred at 150 rpm at room temperature (20 °C) for 40 minutes to obtain derivatized cellulose. The mixture obtained here is a 26 wt% dispersion of derivatized cellulose solids in S2020.

[0117] After 40 minutes, 233 g of S2020 was added to the derivatized cellulose (16 wt% solids in the dispersion). This gives a mixture in S2020 of about 16 wt% derivatized cellulose solids.

[0118] The mixture was then heated to 78 °C ± 1.5 °C and continuously stirred while adding dried DALTOCELL F456 through a dropping funnel. The reaction mixture was then left stirring until an isocyanate prepolymer with an NCO value of about 12% was obtained (measured by titration according to DIN53185). A stable dispersion containing 10 wt% of derivatized cellulose as a solid in the dispersion was obtained, and no significant sedimentation was observed even after 24 hours.

[0119] The mixture was filtered off, washed with acetonitrile, and by FT-IR analysis (in AIR mode) of the dried cellulose, the urethane peak (1730 cm -1 ) and the isocyanate peak (2240 cm -1 ) were confirmed.

[0120] Comparative Example 1 Microcrystalline cellulose (Avicel) was dried at 60 °C under reduced pressure for 12 hours to reduce the moisture content in the cellulose from 6.6 wt% to 2 wt% (based on the total weight of the cellulose). 40 g of the dried cellulose was weighed into a reaction flask, and subsequently anhydrous dimethyl sulfoxide (solvent) was added, and the mixture (20% cellulose in the solvent) was stirred at room temperature for 1 hour. While vigorously stirring for 30 minutes under a nitrogen atmosphere, 56 g of isocyanate S3050 (a mixture of 50% 4,4’-MDI and 50% 2,4’-MDI) was added to the reaction flask (0.3 mol of MDI per mol of OH1). The cellulose was filtered off and washed with dry acetonitrile. Then it was dried under reduced pressure. By FT-IR analysis, the urethane peak (1730 cm -1 ) and the isocyanate peak (2240 cm -1 ) were confirmed.

[0121] The derivatized cellulose prepared as described above was dispersed by high-shear mixing at 3000 rpm for 4 hours in SUPRASEC 2144 (MDI prepolymer). A stable dispersion containing 10 wt% of the derivatized cellulose as a solid in the dispersion was obtained, and no significant sedimentation was observed even after 24 hours.

[0122] Comparative Example 2 α - cellulose (ARBOCEL BE600 - 30) was dried at 80 °C for 3 hours under reduced pressure to reduce the moisture content in the cellulose from 6.6 wt% to 2 wt% (based on the total weight of the cellulose). 100 g of the dried cellulose was weighed into a reaction flask, and subsequently 513 g of SUPRASEC2020 (S2020) was added into the reaction flask under a nitrogen atmosphere. Thereby, a mixture in S2020 with a cellulose solid content of about 16 wt% was obtained. This mixture was heated to 78 °C ± 1.5 °C and continuously stirred while adding the dried DALTOCELL F456 through a dropping funnel. Then, the reaction mixture was left while being mixed until an isocyanate prepolymer having an NCO value of about 12% was obtained (measured by titration according to DIN53185). A mixture containing 10 wt% of cellulose as a solid in the mixture was obtained, and this mixture was not stable, and sedimentation was observed after 24 hours.

[0123] Filtered from the mixture, washed with acetonitrile, and according to the FT - IR analysis (in AIR mode) of the dried cellulose, the peak of urethane (1730 cm -1 ) and the peak of isocyanate (2240 cm -1 ) were not confirmed.

[0124] Comparative Example 3 α - cellulose (ARBOCEL BE600 - 30) was dried at 80 °C for 3 hours under reduced pressure to reduce the moisture content in the cellulose from 6.6 wt% to 2 wt% (based on the total weight of the cellulose). 100 g of the dried cellulose was weighed into a reaction flask, and subsequently 443 g of SUPRASEC2020 (S2020) was added into the reaction flask under a nitrogen atmosphere. This slurry was stirred at 150 rpm at room temperature (20 °C) for 40 minutes. The resulting mixture is a mixture with a cellulose solid content of 18.4 wt% in S2020.

[0125] After 40 minutes, 70 g of S2020 was added to the derivatized cellulose. Thereby, a mixture with a cellulose solids content of about 16% by weight in S2020 was obtained. The mixture was heated to 78 °C ± 1.5 °C and continuously mixed while adding dry DALTOCEL F456 with a dropping funnel. The reaction mixture was left mixing until an isocyanate prepolymer with an NCO value of about 12% was obtained (measured by titration according to DIN53185). A mixture containing 10% by weight of cellulose as a solid was obtained, but this mixture was not stable and sedimentation was observed after 24 hours.

[0126] According to FT-IR analysis (in AIR mode) of the cellulose separated by filtration from the mixture, washed with acetonitrile, and dried, the urethane peak (1730 cm -1 ) and the isocyanate peak (2240 cm -1 ) were not confirmed.

[0127] Application examples The following examples show that a stable dispersion containing a derivatized polysaccharide produced according to the present invention is very suitable for use as an adhesive when applied to a lap joint.

[0128] The following examples compare a stable dispersion containing a derivatized polysaccharide produced according to the present invention with an equivalent isocyanate prepolymer not containing the derivatized polysaccharide.

[0129] Production of lap joints The stable dispersion obtained in Example 1 was spread on the adjusted surface of a beech support at an application amount of 0.032 g / cm 2 (resin amount 0.2 g) to form an adhesive line with a thickness of 0.1 mm, and a lap joint according to the present invention was produced in pairs with a support not containing an adhesive. A comparative lap joint was produced by applying the prepolymer from Example 1 that does not contain the dispersed polysaccharide (referred to as prepolymer S2144). Each support series consisted of 6 lap joints.

[0130] The mechanical properties of the lap joints were then tested (shear strength testing). The maximum breaking load of the beech wood lap joints was compared for each prepolymer. From this data it can be concluded that the lap shear strength for the inventive lap joints is 100% higher than the comparative lap joints.

[0131] These results indicate that adhesives made from stable dispersions containing the derivatized polysaccharides of the present invention are stronger than wood, resulting in failure of the substrate.

[0132] In summary, these results show a significant improvement in mechanical properties compared to the cellulose-free prepolymer.

Claims

**Claim 1** A method for producing a stable dispersion of derivatized polysaccharide in an isocyanate-based liquid, comprising: (1) Supplying at least one polysaccharide containing at least one polysaccharide compound and having a water content of less than 6% by weight based on the total weight of the polysaccharide, and an isocyanate-based liquid containing at least one isocyanate group-bearing compound, and pre-reacting the at least one polysaccharide with the isocyanate-based liquid. The resulting composition is then mixed at room temperature Tr or, when Tm > Tr, at the melting temperature Tm of the isocyanate-based liquid for at least 10 minutes so that the molar ratio of the number of moles of isocyanate groups in the isocyanate group-bearing compound to the number of moles of OH groups derived from the polysaccharide compound is in the range of 0.3 to 0.7 to obtain a derivatized polysaccharide (derivatization step); (2) Diluting the derivatized polysaccharide obtained in step (1) with an isocyanate-based liquid containing at least one isocyanate group-bearing compound so that the amount of the derivatized polysaccharide in the isocyanate-based liquid is in the range of 10 to 33% by weight based on the total weight of [derivatized polysaccharide + isocyanate-based liquid] (dilution step); (3) Adding an isocyanate-reactive composition containing at least one isocyanate-reactive compound to the composition obtained after the dilution step at a high temperature higher than the melting temperature Tm of the isocyanate-based liquid used in the dilution step and lower than 120°C, and mixing for at least 60 minutes to obtain a stable dispersion containing 5 to 20% by weight of the derivatized polysaccharide in the isocyanate-based liquid based on the total weight of the stable dispersion, wherein the stable dispersion has an NCO value in the range of 6 to 25% (dispersion step); The above method comprising at least the above steps. **Claim 2** The production method according to claim 1, wherein the derivatization step, the dilution step, and the dispersion step are carried out in the same reaction vessel. **Claim 3** The production method according to any one of claims 1 to 2, wherein the isocyanate-based liquid used in the derivatization step and the dilution step is the same or different. **Claim 4** The production method according to any one of claims 1 to 3, wherein both the dilution step and the derivatization step are carried out at room temperature Tr or, when Tm > Tr, at the melting temperature Tm of the isocyanate-based liquid. **Claim 5** The manufacturing method according to any one of claims 1 to 4, wherein at least one polysaccharide in the derivatization step is present in an amount in the range of 13 to 57% by weight based on the total weight of at least one polysaccharide and at least one compound used in combination therewith.

6. The manufacturing method according to any one of claims 1 to 5, wherein the derivatization step is carried out at a temperature lower than 70°C and higher than at least the melting temperature Tm of the isocyanate-based liquid. Method.

7. The manufacturing method according to any one of claims 1 to 6, wherein the derivatization step is carried out for at least 10 minutes.

8. The manufacturing method according to any one of claims 1 to 7, wherein the derivatized polysaccharide obtained in the derivatization step is diluted with an isocyanate-based liquid containing at least one isocyanate group-bearing compound so that the amount of the derivatized polysaccharide in the isocyanate-based liquid is in the range of 10 to 33% by weight based on the total weight of the derivatized polysaccharide and the isocyanate-based liquid.

9. The manufacturing method according to any one of claims 1 to 8, wherein the derivatized polysaccharide obtained in the derivatization step is diluted with an isocyanate-based liquid containing at least one isocyanate group-bearing compound so that the NCO value of the dilution composition is in the range of 14 to 50%.

10. The production method according to any one of claims 1 to 9, wherein at least one polysaccharide is selected from the group consisting of cellulose-based compounds; starch; agarose; alginic acid; alguronic acid; α-glucan; amylose; amylopectin; arabinoxylan; β-glucan; carlose; capsulan; carrageenan; cellodextrin; celluline; chitin; chitosan; chrysolaminarin; curdlan; cyclodextrin; DEAE-sepharose; dextran; dextrin; α-cyclodextrin; ficoll; fructan; fucoidan; galactoglucomannan; galactomannan; gellan gum; glucan; glucomannan; glycocalyx; glycogen; hemicellulose; hypromellose; icodextrin; kefiran; laminarin; lentinan; levan; lichenin; maltodextrin; mixed-linkage glucan; mucus; natural gum; oxidized cellulose; paramylon; pectic acid; pectin; pentastarch; pullulan; polydextrose; polysaccharide peptide; porphyran; pullulan; schizophyllan; sepharose; sinistrin; schizophyllan; sugammadex; welan gum; xanthan gum; xylan; xyloglucan; dimosan; glycosaminoglycan, chondroitin, chondroitin sulfate, dermatan sulfate, heparan sulfate, heparin, heparinoid, hyaluronan, keratan sulfate, restylene, sodium hyaluronate, and slodexide; and mixtures thereof.

11. The production method according to any one of claims 1 to 10, wherein at least one polysaccharide is a cellulose-based compound selected from the group consisting of cellulose, nanocellulose, art silk, bacterial cellulose, bamboo fiber, carboxymethyl cellulose, cellodextrin, cellophane, celluloid, cellulose acetate, cellulose acetate phthalate, triacetate cellulose, cellulosome, cotton, croscarmellose sodium, crystallate, cyethylaminoethyl cellulose, dissolved pulp, ethulose, ethyl cellulose, fique, hydroxyethyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl cellulose, hypromellose, lyocell, mercerized pulp, methyl cellulose, microbial cellulose, microcrystalline cellulose, modal (fabric), nitrocellulose, parkesine, perloid, pulp, paper, rayon, sodium cellulose phosphate, supima, viscose, vulcanized fiber, wood fiber, and mixtures thereof.

12. The production method according to any one of claims 1 to 10, wherein at least one polysaccharide is a starch selected from the group consisting of corn starch, amylose, acetylated distarch adipate, amylomaize, amylopectin, cyclodextrin, dextrin, dialdehyde starch, erythronium japonicum, high fructose corn syrup, hydrogenated starch hydrolysate, hydroxyethyl starch, hydroxypropyl distarch phosphate, maltitol, maltodextrin, maltose, pentastarch, phosphorylated distarch phosphate, potato starch, starch, waxy corn, waxy potato starch, and mixtures thereof.

13. At least one isocyanate group-bearing compound is methylene diphenyl diisocyanate in the form of 2,4'-isomer, 2,2'-isomer, 4,4'-isomer, and mixtures thereof, a mixture of methylene diphenyl diisocyanate and its oligomers, or their derivatives having urethane groups, isocyanurate groups, allophanate groups, biuret groups, uretonimine groups, uretdione groups, and / or iminooxadiazinedione groups, and mixtures of the above substances; toluene diisocyanate and mixtures of their isomers; tetramethylxylylene diisocyanate; 1,5-naphthalene diisocyanate; p-phenylene diisocyanate; tolidine diisocyanate; or a mixture of these organic polyisocyanates, a mixture of one or more of these organic polyisocyanates and methylene diphenyl diisocyanate in the form of 2,4'-isomer, 2,2'-isomer, 4,4'-isomer, and mixtures thereof, a mixture of methylene diphenyl diisocyanate and its oligomers; a polyisocyanate selected from the group consisting of, the production method according to any one of claims 1 to 12.

14. The polysaccharide derivative is in the form of granules, and at this time the granules have a particle size distribution with a D50 of at most 1.0 mm, where D50 is defined as the particle size when 50% by weight of the particles have a size smaller than D50 in accordance with ISO standard 13320:2009, the production method according to any one of claims 1 to 13.

15. The water content in at least one polysaccharide is less than 6% by weight, the production method according to any one of claims 1 to 14.

16. Mixing in the dispersion step is carried out for at least 90 minutes, and the stable dispersion of the derivatized polysaccharide has an NCO value in the range of 6 to 25% by weight, the production method according to any one of claims 1 to 15.

17. The stable dispersion contains 5 to 20% by weight of the derivatized polysaccharide based on the total weight of the stable dispersion, the production method according to any one of claims 1 to 16.

18. Use of the stable dispersion produced according to the production method according to any one of claims 1 to 17 in any one of packaging materials, films, foams, composite materials, adhesives, paints, fabrics, sealants, rheology modifiers, paints, and chromatographic packing agents.