RU2256675C2 - Method of manufacturing silver-containing cellulose materials - Google Patents

Abstract

FIELD: modified cellulose materials.

SUBSTANCE: invention relates to silver-containing microcrystalline cellulose for use as bactericide dressing facilities. Silver-containing cellulose materials are manufactured by impregnating cellulose mixture at room temperature with 0.25-2.0% silver nitrate aqueous solution at ratio of 1 g cellulose material per 15-30 ml AgNO₃ solution. Reaction mixture is heated at 85-150°C during 1-4 h. In order to increase silver content, aqueous silver nitrate solution is supplemented by ammonia and/or glycerol to concentration of ammonia 0.5-15 vol % and that of glycerol 20-50 wt %, while observing the same operational conditions. Starting cellulose mixture can be microcrystalline cellulose, cotton fiber, linen and product thereof, and cotton dressing material.

EFFECT: enabled silver level control in modified cellulose material.

2 tbl, 12 ex

Description

The present invention relates to the production of modified cellulosic materials, more specifically to the production of silver-containing microcrystalline cellulose, silver-containing cotton fabrics, linen, dressings. The resulting materials with a metallic silver content of 0.2-1.0% have a high level of antimicrobial activity in relation to a wide range of different bacterial strains. Such materials can be used as bactericidal dressings, for the production of medical clothing, underwear, bedding, and hygiene items. It can be assumed that based on silver-containing microcrystalline cellulose, effective drugs can be created for the treatment of gastrointestinal diseases. With a higher silver content of 2 to 17.5 wt.%, The materials obtained in accordance with the present invention can be used as filters for disinfecting drinking water, as antistatic agents, for reflecting radar radiation, as screens for electromagnetic radiation.

Antibacterial cellulose fibers and a method for their preparation are described (US Patent No. 5985301, authors K. Nakamura and K. Nakamura, Japan, filing date February 11, 1998, publication date November 16, 1999). In accordance with this patent, cellulose fibers are obtained by dissolving viscose in tertiary N-oxide with a silver-containing material (silver zeolite, silver phosphate and zirconium, magnetized fine powder, followed by wet spinning of the fiber from the resulting mass into water. Strong synthetic fibers up to 5 cm long were obtained from which the dressings with high antimicrobial activity were obtained, however, using the known method, it is impossible to impart antimicrobial activity to natural cellulose fibers, but production of metallized textiles (US Patent No. 5981066, author J. Gabby, Israel, application priority August 9, 1996, publication date November 9, 1999). The process of applying a layer of metal to textile material is carried out by sequential impregnation activation operations material with a solution containing readily oxidizing cations, for example, Pt ²⁺ Sn ²⁺ , Ti ³⁺ Then, the listed metal cations are applied to recover the metals deposited on textiles, for example, Cu ²⁺ , Ag ⁺ , Zn ²⁺ , Ni ²⁺ . To intensify the process, reducers from the range of formaldehyde, hydrazine hydrate are additionally used. This gives a metallized material with a surface fully or partially covered with a layer of metal. In accordance with the known invention receive materials with bactericidal and fungicidal properties, which can be used as carpets, wall coverings, curtains, furniture upholstery, for application on the inner surface of food storage containers. However, such materials cannot be used to create dressings, outerwear, and linen. The known method is multi-stage and complex enough for reproduction.

The objective of the present invention is to provide a method for producing silver-containing microcrystalline cellulose, silver-containing cotton and linen fabrics, linen fiber, dressings with both a low content of metallic silver - 0.2-1.0%, and with a high concentration of silver from 2 to 11-17 wt.%, Material with a silver content of 0.2-1.0% is obtained by a method characterized by the following set of essential features.

1. The cellulosic material at room temperature is impregnated with an aqueous solution of AgNO ₃ and the reaction mixture is heated at 85-100 ° C for 1-4 hours.

2. As the cellulosic material, material from a series containing microcrystalline cellulose with a joint venture of 120 to 275, cotton fiber, fabric and articles made of them, linen fiber, linen and articles thereof, cotton dressing is used.

3. The concentration of AgNO ₃ is 0.25-2 wt.%.

4. The ratio of cellulosic material: AgNO ₃ solution is 1 g per 15-30 ml.

A material with a silver content of 2.0-17.5% is obtained by a method characterized by the following set of essential features.

1. The cellulosic material at room temperature is impregnated with an aqueous solution containing AgNO ₃ , as well as ammonia or glycerin, or a mixture thereof, and the reaction mixture is heated at 85-150 ° C for 0.5-4 hours.

2. As the cellulosic material, material from a series containing microcrystalline cellulose with a joint venture of 120 to 275, cotton fiber, fabric and articles made of them, linen fiber, linen and articles thereof, cotton dressing is used.

3. The concentration of AgNO ₃ is 0.25-2 wt.%, The concentration of ammonia is 0.5-15 wt.%, The concentration of glycerin is 20-50 wt.%.

4. The ratio of cellulosic material: AgNO ₃ solution is 1 g per 15-30 ml.

The information search conducted in the INTERNET databases did not allow finding solutions that completely coincided with the totality of essential features with the declared options. This indicates the compliance of the invention with such a condition of protection as "novelty."

An information search did not reveal the popularity of the proposed systems for introducing finely dispersed silver metal into cellulosic materials, which provides a high level of antimicrobial properties at a low silver concentration: cellulosic material - an aqueous solution of AgNO ₃ , cellulosic material - an aqueous solution of AgNO ₃ , ammonia and glycerol. Based on the information published in the scientific literature, one could not expect such systems to be able to provide a solution to the problem. This non-obviousness of the claimed invention allows us to argue that the solution as a whole (options) corresponds to such a condition of patentability as "inventive step".

To confirm the compliance of the invention with the condition "industrial applicability" and to better understand the essence of the invention, we give examples of specific implementations of the invention. Obviously, the examples do not exhaust the essence of the invention.

Example 1. 0.5 g of microcrystalline cellulose with SP 170 is placed in a 50 ml flask. At room temperature, 10 ml of a 2% (wt.) Aqueous solution of AgNO _{3 are} added. The reaction mixture is heated in a boiling water bath. In this case, the material darkens. Heating is stopped when a constant color is achieved - 1.5 hours. The sample is washed with excess water until a quality reaction to ion silver occurs. The amount of silver in the sample of the obtained material is determined by elemental analysis with a silver content of 0.8 wt.% Or higher, or by X-ray fluorescence analysis and X-ray photoelectron spectroscopy with a metallic silver content of 0.1 to 0.8 wt.%. The average grain size of finely divided silver is determined by electron microscopy.

Notes: Example 2 uses microcrystalline cellulose with SP 250; Example 3 uses cotton (article 142, grade 1); in Example 4, dressing material is used - medical gauze (GOST-1172-93) manufactured by Medstroyproekt JSC; in Example 5, linen is used from the production of the Orsha Flax Mill.

Example 6. 10 ml of a 0.25 wt.% Aqueous solution of AgNO ₃ containing 1 wt.% Ammonia solution is added to 0.5 g of linen. The reaction mixture is heated at 100 ° C until the browning stops - 1.5 hours. The material turns dark brown or dark gray. The material is washed with excess water and dried at a temperature of 35-40 ° C.

Example 7. The process is carried out under the conditions of example 6, but glycerol is additionally added to the solution.

Note: in Examples 8, 9, 11, microcrystalline cellulose with SP = 120, 170 and 250 is modified, respectively, in Examples 10 and 12, cotton fabric of the brand is used (article 142, grade 1).

The examples suggest that cellulosic materials containing small amounts of silver have the maximum antimicrobial activity.

Dissolved silver was regenerated by treating the washings and filtrates with ion-exchange resins.

Claims (4)

1. The method of obtaining silver-containing cellulosic materials by exposing them to a water-soluble silver salt, consisting in the fact that the cellulosic material is impregnated at room temperature with an aqueous solution of 0.25 - 2.0 wt.% AgNO ₃ and the reaction mixture is heated at 85 - 150 ° C within 1 to 4 hours 2. The method of producing silver-containing cellulosic materials according to claim 1, wherein the material from the series containing microcrystalline cellulose with a joint venture of 120 to 275, cotton fiber, fabric and products from them, linen fiber, linen and products made from them are used as cellulosic material cotton dressings. 3. The method for producing silver-containing cellulosic materials according to claim 1, wherein the ratio of cellulosic material: AgNO ₃ solution is 1 g per 15 - 30 ml. 4. The method of obtaining silver-containing cellulosic materials according to claim 1, which consists in the fact that ammonia, glycerin, or a mixture of ammonia and glycerol are additionally added to an aqueous solution of AgNO ₃ ; the concentration of AgNO ₃ is 0.25 - 2.0 wt.%, the concentration of ammonia is 0.5 - 15 vol.%, the concentration of glycerol is 20 - 50 wt.%, the ratio of cellulosic material: aqueous solution is 1 g per 15-30 ml, heat the reaction mixture at 85 - 150 ° C for 1 to 4 hours