Abstract:
Non-ionic water-soluble cellulose ethers modified with 3-azido-2-hydroxypropyl groups bound via an ether link are provided having a molar degree of substitution MSAHP in the range from 0.001 to 0.50. Exemplary cellulose ethers are alkyl celluloses, including methyl, hydroxyalkyl (e.g. hydroxyetbyl or hydroxypropyl) or alkylhydroxyalkyl cellulose (e.g. methylhydroxyethyl). Reaction products with alkyne compounds are also provided, resulting in a terminal alkyne group. The reaction of azide with the alkyne proceeds as a 1,3-dipolar cycloaddition reaction, advantageously with Cu(I) or ruthenium catalysts. A multiplicity of cellulose ethers can be obtained from the conversion reaction. Variations in the macroscopic properties can be achieved by controlled modification, ranging from increased or reduced viscosity. The reaction, taking place within a few seconds, requires only minimal catalyst. Gel formation is reversible by adjustment of the pH such that a monophasic system (high-viscous fluid) arises again from a biphasic system (gel+low-viscous water phase).
Abstract:
The invention relates to the use of non-ionic, insoluble cellulose ethers having 3-azido-2-hydroxypropyl (AHP) groups, which are linked to the cellulose via an ether link, wherein the molar substitution degree MSAHP is in the region of 0.001 to 0.30, for the production of insoluble, solid adhesives. The cellulose ethers substituted by AHP groups are reacted in the presence of a copper or ruthenium catalyst with alkine compounds, such as phenylacetylene, propargyl alcohol, propiolic acid or heterocyclic compounds, which have a substituent with a terminal alkine group. The reaction of the azide with the alkine occurs as a 1,3-dipolar cyclcoaddition reaction at room temperature within a few seconds, and an insoluble, solid adhesive is obtained. The adhesive is suitable in particular for adhering paper, cardboard or wood.
Abstract:
Non-ionic water-soluble cellulose ethers modified with 3-azido-2-hydroxypropyl groups bound via an ether link are provided having a molar degree of substitution MSAHP in the range from 0.001 to 0.50. Exemplary cellulose ethers are alkyl celluloses, including methyl, hydroxyalkyl (e.g. hydroxyethyl or hydroxypropyl) or alkylhydroxyalkyl cellulose (e.g. methylhydroxyethyl). Reaction products with alkyne compounds are also provided, resulting in a terminal alkyne group. The reaction of azide with the alkyne proceeds as a 1,3-dipolar cycloaddition reaction, advantageously with Cu(I) or ruthenium catalysts. A multiplicity of cellulose ethers can be obtained from the conversion reaction. Variations in the macroscopic properties can be achieved by controlled modification, ranging from increased or reduced viscosity. The reaction, taking place within a few seconds, requires only minimal catalyst. Gel formation is reversible by adjustment of the pH such that a monophasic system (high-viscous fluid) arises again from a biphasic system (gel+low-viscous water phase).
Abstract:
Solutions of cellulose or cellulose ethers in solvent containing triethylheptylammonium chloride, triethyloctylammonium chloride, triethylhexylammonium acetate, triethylheptylammonium acetate, triethyloctylammonium acetate, triethylnonylammonium acetate and/or triethyldecylammonium acetate are provided. The solvent may further include up to 70 wt % of at least one organic solvent, with acetone being the preferred organic solvent. The solution can be formed into a paste for removing paint from wood or metal surfaces. The cellulose (ether) solution can also serve as a reaction medium in which the cellulose and/or the cellulose ether are chemically modified. Finally, the cellulose (ether) solution can be processed into cellulosic shaped articles.
Abstract:
The invention relates to a method for preparing cellulose derivatives which are reversibly crosslinked with glyoxal and thus display delayed water solubility. In the methods, a water-wetted cellulose derivative is mixed at a temperature of between 20 to 70° C. with an aqueous solution containing glyoxal, a monovalent or polyvalent organic acid, and at least one alkaline earth salt and/or alkali salt of phosphoric acid as a buffer substance to reversibly crosslink the cellulose derivative. The amount of glyoxal is 0.010 to 0.050 mol, in each case in relation to 1 mol of anhydroglucose units of the cellulose derivative, and the molar ratio of monovalent or polyvalent organic acid to glyoxal is in the range of 1:1 to 1:12. The cellulose derivative is then dried and milled, and the drying and milling may also be combined. The invention also relates to cellulose derivatives produced according to the method.
Abstract:
Provided is a method for producing an alkyl cellulose having a high viscosity and not having an excessively high gel strength. More specifically, there is provided a method for producing an alkyl cellulose comprising the steps of: mixing a cellulose pulp with a first alkali metal hydroxide solution with stirring to obtain alkali cellulose; reacting the alkali cellulose with an alkylating agent to obtain a first reaction mixture; blending a second alkali metal hydroxide solution with the first reaction mixture with stirring, without further blending of the alkylating agent, to obtain a second reaction mixture; and purifying the second reaction mixture to obtain an alkyl cellulose. There is also provided an alkyl cellulose being produced by the above method and having a degree of substitution of alkyl group of 27 to 33% by weight.
Abstract:
Provided is a method for producing an alkyl cellulose having a high viscosity and not having an excessively high gel strength. More specifically, there is provided a method for producing an alkyl cellulose comprising the steps of: mixing a cellulose pulp with a first alkali metal hydroxide solution with stirring to obtain alkali cellulose; reacting the alkali cellulose with an alkylating agent to obtain a first reaction mixture; blending a second alkali metal hydroxide solution with the first reaction mixture with stirring, without further blending of the alkylating agent, to obtain a second reaction mixture; and purifying the second reaction mixture to obtain an alkyl cellulose. There is also provided an alkyl cellulose being produced by the above method and having a degree of substitution of alkyl group of 27 to 33% by weight.
Abstract:
Non-ionic water-soluble cellulose ethers modified with 3-azido-2-hydroxypropyl groups bound via an ether link are provided having a molar degree of substitution MSAHP in the range from 0.001 to 0.50. Exemplary cellulose ethers are alkyl cell doses, including methyl, hydroxyalkyl (e.g. hydroxyethyl hydroxypropyl) or alkylhydroxyalkyl cellulose (e.g. methylhydroxyethyl). Reaction products with alkyne compounds are also provided, resulting in a terminal alkyne group. The reaction of azide with the alkyne proceeds as a 1,3-dipolar cycloaddition reaction, advantageously with Cu(I) or ruthenium catalysts. A multiplicity of cellulose ethers can be obtained from the conversion reaction. Variations in the macroscopic properties can be achieved by controlled modification, ranging from increased or reduced viscosity. The reaction, taking place within a few seconds, requires only minimal catalyst. Gel formation is reversible by adjustment of the pH such that a monophasic system (high-viscous fluid) arises again from a biphasic system (gel+low-viscous water phase).
Abstract:
The invention relates to a preparation comprising at least one cellulose ether and/or at least one polysaccharide and at least one fatty alcohol, and to the production and use thereof, in particular in construction materials.