WO2012038273A1

WO2012038273A1 - Polyurethane system for manufacturing elastic means with improved sanitary and hygienic properties

Info

Publication number: WO2012038273A1
Application number: PCT/EP2011/065637
Authority: WO
Inventors: Ara Arshavirovich Abramyan; Mikhail Mefodievich Afanasyev; Viacheslav Ivanovich Beklemyshev; Anatoly Ivanovich Grigoriev; Igor Ivanovich Makhonin; Petr Ivanovich Makhonin; Umberto Orazio Giuseppe Maugeri; Lana Nizamovna Mukhamedieva; Oleg Igorevich Orlov; Vladimir Aleksandrovich Solodovnikov
Original assignee: Fondazione Salvatore Maugeri Clinica del Lavora e della Riabilitazione; SIB LABORATORIES Ltd; CLOSED STOCK Co "INSTITUTE OF APPLIED NANOTECHNOLOGY"
Current assignee: Fondazione Salvatore Maugeri Clinica del Lavora e della Riabilitazione; SIB LABORATORIES Ltd; CLOSED STOCK Co "INSTITUTE OF APPLIED NANOTECHNOLOGY"
Priority date: 2010-09-22
Filing date: 2011-09-09
Publication date: 2012-03-29
Anticipated expiration: 2013-03-22
Also published as: RU2447098C1

Abstract

The invention concerns new compositions on the base of polyurethanes, in particular, polyurethane systems intended for manufacturing elastic products, preferably, for medical purposes, such as, orthopedic antibedsore mattresses, seats-pillows, anatomic pillows, insoles-instep supports, orthopedic corsets, kneecaps, bandage products, footwear for various kinds of defects of foots and the like. Also improved polyurethane wound dressings can be produced. The new modified polyurethanes have improved sanitary and hygienic properties which render them specifically suitable for the claimed uses. The polyurethane system of the invention, with improved sanitary and hygienic properties, contains a polyol compound (component А), a isocyanate compound (component В) and a mineral agent (С) dispersed into the polyol compound (component А). The mineral agent (C) consists of a mix of nanostructured powders of bentonite intercalated by ions of silver(Ag⁺) and ions of cerium (Ce³⁺ ), in a ratio between them of 1 : (5-10) parts by weight. The articles produced with the new polyurethane system have clearly improved characteristics in so far as suppression of growths of microorganisms and preventing evolution of volatile toxic organic compounds are concerned.

Description

POLYURETHANE SYSTEM FOR MANUFACTURING ELASTIC MEANS WITH IMPROVED SANITARY AND HYGIENIC PROPERTIES

Field of the invention

The invention concerns chemistry of polyurethanes, in particular a polyurethane system intended for manufacturing of elastic products, preferably for medical purpose, for example orthopedic antibedsore mattresses, seats-pillows, anatomic pillows for back and for head, insoles-instep supports, orthopedic corsets, kneecaps, bandage products, footwear for various kinds of flat-footedness and defects of foots etc. Their technical parameters have the improved sanitary and hygienic properties corresponding to the requirements for their operation. The present invention can be also used for obtaining polyurethane wound dressings.

Prior art

A process for obtaining polyurethane products is traditionally based on the use of a liquid polyurethane jet system whose components are mixed and filled in the form at low pressure; in alternative the formation of products is carried out with a reaction-injection method (REVI-technology). The components of polyurethane jet system are selected depending on requirements for the end-product (density, durability, elasticity, temperature constancy etc.).

At the basis of any polyurethane system there are the compositions containing the following components:

- polyol compounds (component A) intended for structuring and determining molecular weight of polyurethanes, density of the vulcanization grid, structure of the cross- section chemical bonds, i.e. a complex of properties of polyurethanes and their purposes;

- isocyanate compounds (component B) determining speed of urethane-formation, strength properties, light and radiating resistance and also rigidity of polyurethanes.

Prepolymers both on the basis of methylenediphenyldiisocyanates (prepolymer - MDI) and toluenediisocyanates (prepolymer - TDI) are used as isocyanate compounds.

Esters and ethers are used as polyol compounds.

So, for example, a polyurethane system on the basis of diphenylmethanediisocyanate, polyol and polymethylenepolyphenylenepolyiso-cyanate (polymeric MDI) is described for obtaining products from elastic polyurethane (EP 111 121). In the patent EP 392 788 elastic polyurethane products are obtained by interaction of obtained prepolymers or prepolymers with the reactivity composition in relation to isocyanate containing a plenty of water.

In the patent EP 439 792, the use of polyisocyanate compounds on the basis of MDI and TDI, in the presence of prepolymer TDI, in the amount of 21-95% on the polyurethane composition, are disclosed for improvement of tensile strength.

In the patent EP 679 671, the use of a mix of polymeric MDI and TDI containing 3- 20% of TDI, was described for obtaining a polyurethane with low density, increased resilience and improved permanent deformation at compression.

The above mentioned systems for obtaining polyurethanes are based on interaction of polyisocyanate with one or more simple polyesterpolyols and waters. They do not provide effective pores formation. As a result the density of obtained polyurethanes is increased and such parameters as sufficient resistance to stress, worsens.

For obtaining products with improved properties it is described the use of polymer- polyols in polyurethane systems on the following base:

- dispersions of polyacrylonitrile, polystyrene (SAN-polymeric polyols);

- polyols with a dispersion of polyurea (PHD-polyols);

- polyisocyanate polyols with polyadditives (PIPA-polyols) - dispersions of polyurethane and others copolymer-polyols.

In the patent EP 418 039 the method for obtaining PIPA-polyol and the method for obtaining elastic polyurethanes with improved resistance to stress by application of said PIPA-polyol is described. Application of PIPA-particles with a size from 100 up to 700 nm is described in said patent.

In the patent EP 555 721 is described a polyurethane system for obtaining elastic polyurethanes with a high amount of polyol having a high content of oxypropylene and, at the same time, a rather low amount of polyisocyanate.

It follows from the above mentioned results that a variety of initial components for polyurethane systems, and chemical reactions accompanying their synthesis, provides the opportunity of creation of various materials with the specified physical and chemical properties. According to this, new opportunities of application of polyurethane systems for obtaining products with improved technical characteristics, are continuously developped. For example, in the specification of the patent RU No. 2040530, a polyurethane system for obtaining products with improved properties on the basis of structures containing polyesterpolyol (component A), polyisocyanate (component B) and a component (C) dispersed in the component (A) is disclosed.

Particles of graphite foam are used as a component (C) in the given patent. They are dispersed in a part of polyesterpolyol and the last part of polyesterpolyol is mixed with other agents including the activator, the accelerator, etc. The use of particles of graphite foam in a polyurethane system and also an additional agent such as casein in the powdery form, provides an elastic polyurethane with improved properties of non inflammability derived from the given materials.

In the specification of the patent EP 2007/057405, published on 18 July 2007 (application of the Russian Federation N. 2009105824, published on 27 August 2010, application US N. 2009/0326148, published on 31 December 2009) a polyurethane system is described containing structures on the basis of polyol compounds (component A), isocyanate compounds (component B) and the mineral agent (C) which is dispersed in polyol compounds (component A).

The polyol component (A) contains the agent (C), on the basis of an aluminosilicate mineral, dispersed in it.

According to the given invention other agents (D) are dispersed in the polyol component (A) including the metal catalyst and a thixotropic agent such as silicon dioxide with a specific surface of 150m /g or more.

The agent (C) on the basis of the aluminosilicate mineral dispersed in the polyol component (A) has the average size of particles of 100 microns with a size of pores from 2 up to 5 A. The polyurethane composition contains 1.2-2 % b.w. (by weight) of the agent (C). Application of the named aluminosilicate mineral (the agent (C)) in the polyurethane composition provides adsorption of water during formation of urethane links. This promotes regulation of speed of interaction of isocyanate groups both with hydroxyl- containing oligomers and water, in the presence of the catalyst in the polyurethane system.

Polyester polyols are used as a component (A) in the given patent. Polyester polyols or a mix of polyester polyols consisting of high-molecular elastic polyols with molecular weight in the range from 1500 up to 10000, are preferably used. Prepolymers MDI, or a mix of polymers MDI with an amount of the isocyanate group (NCO) from 15 up to 40%, on the total weight of prepolymer, are preferably used as the component (B).

The specification of the patent RU No. 2379060, published on 10 September 2007, is also known. According to it a polyurethane system is known which contains structures on the basis of a polyol compound (component A), a isocyanate compound (component B) and the agent (C) which is dispersed into the polyol compound (component A).

The invention is intended for use in surgery and traumatology for healing wounds of various etiologies.

Simple high-molecular polyesterpolyol containing dispersed in it activating additives, namely: the catalyst of urethane-formation, on the basis of a mix of tertiary amines and organotin compounds; a chain extender of polyurethane; the foaming agent, a foam-opener and a foam-hardener, are used as the polyol compounds in polyurethane systems according to the given invention. A mix of prepolymers MDI is used as isocyanate compound (component B).

However, a wound dressing obtained according to the given invention is poorly effective for antimicrobic influence on wounds of various etiologies.

The Patent Application of the Russian Federation No. 2009105824 is the nearest analogue of the present declared invention, with reference to the set of components used in the polyurethane system.

The given polyurethane system is intended for manufacturing products used in motor industry, in particular for manufacturing seats, instrument panels, boards, boxes and details of internal or external car facing.

However this polyurethane system does not correspond to requirements for manufacturing products with improved sanitary- and-hygienic properties. Such requirements are necessary for products of medical use including: antibedsore mattresses, sitting-pillows, anatomic pillows for the back or for the head, insoles-instep supports, orthopedic corsets, kneecaps, footwear for various kinds of flat-footedness and defects of foot and also for obtaining polyurethane wound dressings.

Summary of the invention

The problem of the present invention consisted in the creation of a polyurethane system for manufacturing products with improved sanitary and hygienic properties under use, both due to suppression of growth of microorganism in the products and due to improvement of their chemical stability deriving from decreasing in gas evolution of the volatile toxic organic compounds, displaying at operation of products under influence of agents such as temperatures, light, mechanical loadings and other factors which lead to destruction of polymeric materials.

For the solution of the problem outlined, it is described a polyurethane system for manufacturing products with improved sanitary and hygienic properties containing structures, on the basis of polyol compounds (component A), isocyanate compounds (component B) and the mineral agent (C) which is dispersed in polyol compound (component A). According to the invention a mix of nano structured powders of bentonite intercalated by ions of silver (Ag⁺) and ions of cerium (Ce³⁺), in a ratio in the mix of 1 : (5- 10) (weight parts) is used as the agent (C) dispersed in the polyol component (A).

Thus the polyurethane system for manufacturing products according to the invention is used at the following contents of components, in % b.w.:

polyol component (A) 45.0 - 75.0 isocyanate component (B) 25.0 - 55.0 mix of nano structured powders of bentonite

on the total amount of the polyol component (A) 0.1 - 0.5

According to the invention a nanostructured powder of bentonite intercalated by ions of cerium (Ce³⁺) is obtained by modifying a semifinished product of bentonite with 0.3-2.0% water solution of nitrate salt of cerium Ce(N0₃)3-6H₂0. Semifinished product of bentonite is obtained, after its enrichment with cations of sodium (Na⁺), by processing with a 3-10% water solution of sodium chloride and subsequent cleaning from anions of chlorine. After intercalation bentonite is cleaned from salts of sodium by means of grinding.

According to the invention preferably is used as polyol compound (component A) with a hydroxyl number of mg(KON)/g of 66.0-77.0, and a content of water of 2-4% b.w..

According to the invention as isocyanate compound (component B) is used a compound on the basis of prepolymer MDI with an amount of isocyanate group (NCO) from 23 up to 40.0% on the total weight of the prepolymer, and preferably with an amount of group (NCO) of 30%. According to the invention the polyol compound (component A) and the isocyanate compound (component B), at formation of polyurethane system for manufacturing a product, have the following ratio: (2-3) : (1-3) (parts b.w.).

According to the invention, simple high-molecular polyesterpolyol with the molecular weight 3000-10000, obtained on the basis of propylene oxide or ethylene oxide, with a content of water of 2.0-4.0 % b.w., is preferably used as the polyol compound (component A).

According to the invention, high-molecular polyesterpolyol on the basis of propylene oxide or ethylene oxide contains, in addition, dispersed in it, activating additives, namely: the catalyst of urethane-formation on the basis of a mix of tertiary amines and organotin compounds in a ratio 1: 1; a chain extender of polyurethane; a foaming agent; a foam-opener and a foam-hardener in the following contents with reference to the component (A), expressed as % b.w.:

foaming agent 2.0 - 4.0

catalyst of urethane-formation 0.05-0.4

chain extender of polyurethane 0.2-1.5

foam-opener 0.2-1.5

foam-hardener 0.2-1.5

According to the invention a mix of prepolymers is used as isocyanate compound (component B). One of prepolymers is obtained from a mix of 4.4, 2.4 and 2.2-isomers of diphenylmethanediisocyanate and low-molecular polyol from propylene oxide with molecular weight 240-250. The second prepolymer is synthesized by heat treatment of the specified mix of isomers of diphenylmethanediisocyanate.

According to the invention polyol compound (component A) on the basis of propylene oxide or ethylene oxide and isocyanate compound (component B) on the basis of the specified mix of prepolymers, have the ratio (2-4) : 1 (parts b.w.) in the formation of polyurethane systems.

By using the products realized according to the present invention, growth of microorganisms is suppressed and gas evolution of volatile toxic organic compounds is decreased. That considerably improves the properties and enlarges the use of elastomeric products, obtained on the basis of polyurethane system according to the invention, for medical purposes. Said results are explained as follows:

- presence in the polyurethane system of a nano structured powder of bentonite, intercalated by ions of silver (Ag⁺ ), in the polyol component (A). This system possesses both activity against many kinds of microorganisms (including aerobic and anaerobic bacteria, yeast and funguses) and prolongs antimicrobic and fungicidal action due to contact of a product with the biological environment;

- presence in the polyurethane system of a nano structured powder of bentonite intercalated by ions of cerium (Ce³⁺) included in the polyol component (A). This system possesses antimicrobic action and improves chemical resistance of obtained polyurethane products, owing to decrease in gas evolution of the volatile toxic organic compounds, arising when the products are used i.e. when influence of such factors as temperature, light, mechanical loadings, and like rises. These results are explained by high potential of activity of ions of cerium to inhibition of oxidation processes.

Analysis of the available art did not reveal technical documents describing products with a set of characteristics corresponding to those declared in the present application and providing results as described above.

The result of analysis of available art testifies the conformity of the present patent application to criteria of "novelty" and "degree of inventiveness".

The present patent application can be industrially realized by using known technological processes, available equipments and materials intended for manufacturing structures and means for medical purposes.

Brief description of the figures

The essence of the invention is explained by means of the submitted figures (Fig. 1 and Fig. 2), with chromatograms of full ionic current of volatile organic compounds released from polyurethane materials according to Examples 1 and 2, and also by choice of raw components, examples of its realization and results of the tests.

Detailed description of the invention

Active preparations and polymeric components known in the pharmaceutical industry and in medicine, intended for manufacturing various compounds, are used for realizing the present invention. Various polyurethane systems containing a polyol compound (component (A) and isocyanate compound (component (B) are used for the realization of the present invention by manufacturing polyurethane elastic means.

The choice of the components A and B is determined by the technological process for manufacturing the elastomeric products and by their intended use.

1. For obtaining elastomeric products by a method of formation which uses the RTM-technology (Reaction-Injection Method) which is preferably used for obtaining orthopedic means, such as antibedsore mattresses, sitting-pillows, anatomic pillows for back and for head, the following components have to be used:

1.1. A polyol component (A) - trade mark Voralux HK 490, with a hydroxyl number mg(KON)/g = 66.0-77.0, and a content of water of 2.16-2.54 %. The given polyol component preferably has a hydroxyl number mg(KON)/g = 74.2, and a content of water of 2,31 %.

1.2. An isocyanate component (B) - trade mark Specflex NE 371. It identifies prepolymers MDI, whose number of the isocyanate group (NCO) is from 28.8 up to 30.8 %, on the total weight of prepolymer. The mentioned isocyanate component (B) preferably has isocyanate groups (NCO) in amount of 30%.

The products named in item 1.1 and 1.2 are optimal for obtaining elastomeric articles with a method of formation which uses the RIM-technology; they are preferably used for obtaining orthopedic means.

The quantitative contents of a polyol component (A) and an isocyanate component (B), in polyurethane system specified in the invention, is the optimum, taking into account also the specified ratios; the process of urethane-formation qualitatively worsens, or the characteristics of the obtained products considerably change as to their density, at decrease in the quantitative content of the given components in the system and at change of their weight ratio. The given parameter is a determining parameter for manufacturing means of orthopedic use, of the above specified type, and it is preferably in limits from 80 up to 100 kg/m³.

2. The following method is used for obtaining a polyurethane system which is used for obtaining elastomeric products, as wound dressings, according to techniques described in the Russian patent No. 2379060, when formation of dressings is carried out directly on the wound surface, after mixing the components A and B. 2.1 The polyol compound (component A) is a simple high-molecular polyesterpolyol with the molecular weight 3000-10000. It is obtained on the basis of propylene oxide or ethylene oxide, with a content of water of 2.0-4.0 % b.w.. The given product has a trade mark LAPROL 3003, 3603, 5003, 6003. Analogues of these products have trade marks "Raradol" and "Demosthenes".

2.1.1 Activation additives, namely the catalyst of urethane-formation, the chain extender of polyurethane, a foam-opener, a foam-hardener and the foaming agent are as follows: low-boiling organic liquids, for example, H-pentene, isopentene, methylcyclopentene, etc., are used as the foaming agent; a mix of tertiary amines and organotin compounds in the ratio of 1 : 1 (parts b.w.), for example, triethylenediamine and dibutyltindioleate is used as the catalyst for urethane-formation (mixes of tertiary amines and organotin compounds possess a synergistic effect); alkanolamines are used as the chain extender.

Polymethylenedisiloxanes, for example, Dabko 2525 of the company Ajr Prodaks or Tegostab 8715 of the company Goldshmidt are used as a foam-hardener. High- molecular polyols are used for adjustable foam-openers.

Above mentioned activation additives are dispersed into a polyol component (A) specified in the item 2.1. The quantitative contents of activation additives specified in the present invention are optimum for obtaining effective polyurethane system intended for obtaining means as bandages for closing of wounds of various etiologies. This is also proved in the known specification of the Russian patent N. 2379060.

2.2. An isocyanate component (B) is a mix of prepolymers. One of them is obtained from a mix of 4.4-, 2.4-and 2.2-isomers of diphenylmethanediisocyanate and low- molecular polyol from propylene oxide, with molecular weight 240-250. The second prepolymer is synthesized by heat treatment of the specified mix of isomers of diphenylmethanediisocyanate. The named isocyanate component (B) has a trade mark Suprasek 2456 (company Hantsman).

The isocyanate component B chosen for realization of the present invention, its quantitative content in polyurethane system, the weight ratio between used polyol and isocyanate components specified in the present invention are the optimum. Said conditions correspond also to conditions for manufacturing wound dressings with the specified characteristics, using a polyurethane; manufactured dressings have a wide range of density from 44 kg/m 3 up to 100 kg/m 3. This is proved by the known specification of the Russian Patent No. 2379060.

3. For realization of the present invention by creating a polyurethane system suitable to manufacture elastomeric products for medical purposes as mentioned above and without dependence from technological methods, it is used a mineral agent (C), on the basis of nanostructured powders of bentonite, which is dispersed into the polyol component A.

3a. Nanostructured powder of bentonite intercalated by ions of silver (Ag⁺).

Said antimicrobic agent is obtained according to the technology described in the Russian patent RU No. 2330673.

A natural mineral montmorillonite (bentonite in Na-form) is used for obtaining the antimicrobic agent. Bentonite is processed with 3-10% water solution of sodium chloride with subsequent washing and filtering of the obtained semifinished product for removal of chlorine. Then the semifinished product of bentonite is modified by 10-20% solution of silver nitrate, with retention interval of modified bentonite in the specified salt solution. After intercalation, the obtained product is cleaned from salts of sodium; then it is grinded thus obtaining a powder of bentonite. The size of the particles of the powder of bentonite is preferably no more than 150 nm. Processing of the mineral with the named solution of salts is carried out at the ratio in parts by weight of bentonite : solution as 1 : (10-40). The powder of bentonite intercalated by ions of silver contains from 2 up to 8% b.w. of silver, depending on the amount of activating and modifying agents.

The specified amount of the named metal in the bentonite powder is optimum. Increase in amount of metals leads to increase in costs for obtaining the antimicrobic agent and the decrease leads to worsening of antimicrobic activity.

The quantitative contents of a nanostructured powder of bentonite intercalated by ions of silver, specified in the present invention, is the optimum. Antimicrobic properties of polyurethane system, intended for obtaining elastomeric products, worsen at decrease in the content of the given antimicrobic agent in the structure of the polyol component (A). Increase in the quantitative content of the given antimicrobic agent increases expenses for its manufacturing.

3b. Nanostructured powder of bentonite intercalated by ions of cerium (Ce³⁺). Said product is obtained by modifying a semifinished product of bentonite with 0,3- 2,0% water solution of nitrate salt of cerium Ce(N0₃)₃-6H₂C). Bentonite is obtained after its enrichment with cations of Na⁺, by processing with 3-10% water solution of sodium chloride and subsequent cleaning from anions of chlorine. After intercalation bentonite is cleaned from salts of sodium with grinding up to the size of the particles preferably of no more than 150 nm. By testing the salt Ce(N0₃)₃-6H₂0, it was recognized that cerium (metal of variable valency) actively interacts with oxygen with formation of cerium dioxide (Ce0₂), which is an antioxidant having inactivating and blocking influence on formation of peroxides and hydroperoxide radicals, generated in oxidizing processes. The given metal pertains to biologically compatible materials and is used in medicine, for example in prosthetics and stomatology.

A 0,5% water solution of cerium nitrate Ce(N0₃)₃-6H₂0 was used in the process of intercalation of the semifinished product of bentonite, obtained after its enrichment with cations of Na⁺, for realization of the present invention.

The bentonite powder obtained after intercalation, cleaning and grinding contains cerium in the amount of no more than 0,5% b.w..

The quantitative contents of nano structured powder of bentonite intercalated by ions of cerium Ce³⁺ specified in the present invention are the optimum to create the conditions of blocking peroxides which are formed in the oxidizing processes in operating products.

At decrease in the content of the given preparation in a composition of ointment, the activity of ointment in interaction of ions of cerium with free radicals and peroxides is decreased. Increase of the quantitative content of the given component in the polyol component increases costs for its manufacturing.

A 5% water solution of chloride sodium was used at the stage of obtaining the semifinished products of bentonite enriched with cations of sodium; the ultrasonic dispersant Sonopuls HD-2070 (company Bandelin) with power 35-75 W/cm and frequency 20-50 kHz was used at the stage of nano structuring bentonite intercalated by ions of Ag⁺ or ions of Ce³⁺.

A method of microscopy was used for estimation of the size of particles of bentonite.

Polyurethane systems according to the following examples were obtained. Example 1

1. Manufacturing of a polyol component (A) for polyurethane system for obtaining elastomeric products by a method of formation using the RIM-technology (reactionary- injection method).

The given method was used for manufacturing polyurethane orthopedic pillows for the head. In total 163 pillows were produced. Special molds with the specified profile was used for manufacturing pillows.

A mix of nanostructured powders of bentonite intercalated by ions of silver (Ag⁺) and ions of cerium (Ce³⁺) in a ratio in the mix of 1 : 8 was introduced (by mixing over 2 hours under pressure) in a liquid polyol component (A) (trade mark Voralux HK490). 200 litres of polyol and 0.192 kg of the named mix of nanostructured powders of bentonite were used in total.

An isocyanate component (B) (trade mark Specflex NE 371), in amount of 72.0 kg, was used for 200 litres of the polyol component (A). The ratio of the polyol component (A) to the isocyanate component (B) was of 2,6 : 1,01 parts b.w..

The obtained polyurethane system, with kg 1,085 of the component (A) and kg 0,421 of the component (B), was used for manufacturing profiled polyurethane pillows with the following rough parameters: width = cm 34, length = cm 50, thickness of profile (min) = cm 7,0, thickness of profile (max) = cm 12,0. Rough volume of a pillow was 0,016-0,017 m³.

The polyol component (A) and the isocyanate component (B) were input in the profiled form from two nozzles under pressure. After the beginning of foaming (starts in 30sec) the form was closed with a cover. Reaction of urethane-formation lasts 10 minutes as a whole. The produced pillow was taken out from the mould and was dried at room temperature. Elastic means (orthopedic pillows for the head), with density from 87 kg/m up to 90 kg/m were manufactured as a result of the given technological process and the specified amount of components used in the polyurethane system. That corresponds to technology requirements for the given kind of products. Weight of pillows was 1.4 - 1.5 kg- Example 2 - control

The present example was carried out according to the Example 1, but at absence of the mineral component (C) on the basis of a mix of nanostructured powders of bentonite and dispersed into the polyol component (A).

Elastic means (orthopedic pillows for the head) with density from 80 kg/m up to 83 kg/m were manufactured at realization of the given example.

Example 3

A polyol component (A) (trade mark LAPROL 3003) was prepared by careful mixing 100 parts b.w. of polyol and the following additives, parts b.w.:

A mineral component (C) on the basis of a mix of a nanostructured powder of bentonite intercalated by ions of silver (Ag⁺) or ions of cerium (Ce³⁺) at a ratio in the mix, of 1:8, and 0.1 parts b.w. of the polyol component (A) are further input in the polyol component (A), containing the named activation additives.

Suprasek 2456 (company Hantsman) containing 29.5% b.w. of NCO-groups was used as the isocyanate component (B).

33 parts b.w. of the isocyanate component (B) are added for 100 parts b.w. of the polyol component (A) for manufacturing the polyurethane system.

Mixture of the polyol component (A) with the isocyanate component (B) was carried out in a polyethylene vessel of 350-400 ml, at room temperature (20°C). After 50- 60 sec from the mixture, the composition was placed on a model of wound. Within 3-5 minutes after placing, the composition turns in porous "sponge" which is firmly kept on the surface of the wound. Formation of polyurethane "sponge" (polyurethane bandages) is characterized by the following parameters:

start - 25 sec,

swelling - 140 sec,

density of the obtained polyurethane mass (product) - 63 kg/m .

Example 4- control.

The present example was carried out according to the Example 3, but at absence of the mineral component (C) on the basis of a mix of nano structured powder of bentonite dispersed into the component (A).

Polyurethane material with a density of 60 kg/m was obtained at realization of the given example.

Example 5- control.

The given example was carried out according to the Example 3, but at presence of a dispersed mineral component (C) on the basis of nanostructured powder of bentonite intercalated by ions of cerium (Ce³⁺) in amount of 0,1 parts b.w. in the polyol component (A).

Polyurethane material with the density of 63 kg/m was obtained at realization of the given example.

Efficiency of used polyurethane systems for manufacturing products with improved sanitary and hygienic properties, according to Examples 3, 4 and 5, was estimated basing on the presence of antiseptic properties in the products. Estimation of antiseptic properties was carried out by cultivation of colonies of microorganisms (S. aureus) in Petri dishes. Then samples of polyurethane products manufactured according to Examples 3, 4 and 5 were placed in dishes with retention intervals within 5-7 days, at room temperature. Measurement of growth inhibition of test- organisms was carried out after expiration of retention interval. Correlation was carried out according to 4-5 tests.

The research displayed the following results:

- absence of growth of colonies of S. aureus in the samples of products manufactured according to the Example 3, in 7 days (under microscope);

- presence of growth of colonies of S. aureus on the surface of samples of products manufactured according to the Example 4, in 5 days (under microscope); - growth of colonies of S. aureus on the surface of samples of products manufactured according to the Example 5 (under microscope), took place in 5 days but the surface of semination with microorganisms was 3% from the total surface of semination of the sample manufactured according to the Example 4.

The result of the researches testify that sanitary and hygienic properties of the means obtained by use of polyurethane systems are most effective at presence of mixes of nanostructured powders of bentonite intercalated by ions of silver (Ag⁺) and ions of cerium (Ce³⁺) in the polyol component (A).

Efficiency of used polyurethane systems for obtaining products with improved sanitary and hygienic properties according to the Examples 1 and 2, was estimated basing on the presence of gas evolution of toxic volatile organic compounds from the products obtained according to these Examples. What characterizes the chemical stability of polyurethane systems used for manufacturing elastomeric products of medical use.

The estimation was carried out with the method of thermal desorption gas chromatography/mass spectrometry (GOST P ISO 1600 «Air of the closed premises*, section 6). As a result of sanitary-chemical tests of products manufactured with the use of polyurethane systems according to the Examples 1 and 2, it was established the following: release of highly toxic chemical compounds (volatile organic compounds, mainly the residual monomeric compounds) at thermal-oxidative destruction of polyurethane materials, using the polyol component (A) modified by the agent (C), on the basis of a mix of a nanostructured powder of bentonite intercalated by ions of Ag⁺ and Ce³⁺, in polyurethane system according to the Example 1, is lower of 1-2 orders of magnitude, in comparison with the products manufactured without application of the specified agent (C) of the Example 2.

This is demonstrated by Fig. 1 and Fig. 2 in which chromatograms of full ionic current of volatile organic compounds released from polyurethane materials are submitted.

The result of the researches confirms in the whole that the use of a polyurethane system according to the present invention, for manufacturing elastic products, considerably improves their sanitary and hygienic properties, both regarding suppression of growth of microorganisms and decrease in gas evolution of volatile toxic organic compounds, at operation of the products.

Claims

Polyurethane system for manufacturing elastic products having improved sanitary and hygienic properties, both regarding suppression of growth of microorganism and decrease in gas evolution of volatile organic compounds, comprising a polyol compound (component A) and an isocyanate compound (component B), characterized in that the component (A) contains dispersed therein, as component (C), a mixture of nanostructured powders of bentonite intercalated by ions of silver (Ag⁺) and by ions of Ce³⁺, where the ratio of the ions Ag⁺ to the ions of Ce³⁺ is of 1 : (5-10) parts by weight.

Polyurethane system according to claim 1, wherein the mixture of nanostructured powders of bentonite constitutes the 0,1-0,5% by weight of the component (A).

Polyurethane system according to claim 1 having the following content of the essential components:

component (A) 40 - 75 % b.w. component (B) 25 - 60% b.w. component (C) 0.1 - 0.5%

referred to the component (A) Polyurethane system according to claim 1, wherein a bentonite intercalated by ions of Ce³⁺ is used, obtained by treatment of a semifinished product of bentonite with a 0,3- 2% water solution of nitrate salt of cerium Ce(N0₃)3 · 6H₂0.

Polyurethane system according to claim 4, wherein the semifinished product of bentonite is obtained by enrichment with cations of Na⁺, through treatment with a 3- 10% water solution of NaCl, followed by cleaning from the CI^" anions and subsequent grinding of the bentonite, after intercalation.

Polyurethane system according to claim 1, wherein the component (A) is a polyol compound with a hydroxyl number of mg(KON)/g = 66.0-77.0 and a content of water of 2,0-4% b.w..

Polyurethane system according to claim 1, wherein the component (B) is a isocyanate compound, on the basis of prepolymer MD1, with an amount of isocyanate groups (NCO) from 23,0 up to 40.0%, preferably of 30%.

8. Polyurethane system according to claims (6) and (7), wherein the ratio of the polyol compound (component A) to the isocyanate compound (component B) is of A : B = (2-3) : (1 : 3) in parts b.w..

9. Polyurethane system according to claim 1, wherein the component (A) is a polyester polyol with the molecular weight 3.000-10.000, obtained from propylene oxide or ethylene oxide, with a content of water of 2,0-4,0% b.w.

10. Polyurethane system according to claim (9), wherein the component (A) contains activation additives, namely the catalyst of urethane formation on the basis of a mix of tertiary amines and organotin compounds in a ratio 1 : 1 b.w., a chain extender of polyurethane, a foaming agent, a foam-opener and a foam-hardener.

11. Polyurethane system according to claim (10), wherein the additives are contained in the component (A) in the following amounts in % b.w.:

- catalyst of urethane formation 0.05 - 0.4

- chain extender of polyurethane 0.2 - 1.5

- foaming agent 2.0 - 1.5

- foam hardener 0.2 - 1.5

12. Polyurethane system according to claim 1, wherein the isocyanate compound, component (B) is a mix of prepolymers.

13. Polyurethane system according to claim (12), wherein the prepolymer is obtained from a mix of 4,4 / 2,4 / 2,2 isomers of diphenylmethanediisocyanate and a polyol from propylene oxide, with a molecular weight 240-250.

14. Polyurethane systems according to claim (12), wherein a prepolymer is obtained by thermal processing of 4,4 / 2,4 / 2,2 isomers of diphenylmethanediisocyanate.

15. Polyurethane systems according to claims (9) and (12), containing a polyol compound (component (A)), on the basis of propylene oxide or ethylene oxide, and a isocyanate compound (component (B)) on the basis of prepolymers of diphenylmethanediisocyanate, in a ratio (A) : (B) of (2-4) : 1 parts by weight.