PL228387B1 - Nanocomposite material, method for producing nanocomposite material and its applications - Google Patents

Description

(12) PATENT DESCRIPTION ₍ i ₉₎ PL ₍ n) 228387 (13) B1 (21) Filing number: 408177 (22) Filing date: May 9, 2014 (51) Int.CI.

B65D 65/38 (2006.01) B65D 81/24 (2006.01) D21H 17/63 (2006.01) D21H 17/67 (2006.01) D21H 21/36 (2006.01) D21H 27/10 (2006.01) (54)

Nanocomposite material and its application

(73) The right holder of the patent: JAGIELLONIAN UNIVERSITY, Krakow, PL (72) Inventor (s): (43) Application was announced: JOANNA ŁOJEWSKA, Cracow, PL 23/11/2015 BUP 24/15 TOMASZ ŁOJEWSKI, Cracow, PL JACOB L. THOMAS, Krakow, PL ROMAN J. JĘDRZEJCZYK, Cracow, PL DOMINIKA PAWCENIS, Cracow, PL (45) The grant of the patent was announced: JAKUB M. MILCZAREK, Łódź, PL 30/03/2018 WUP 03/18 BARBARA GIL, Krakow, PL ANDRZEJ KOŁODZIEJ, Gliwice, PL (74) Representative: thing, pat. Piotr Godlewski

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PL 228 387 B1

Description of the invention

The subject of the invention is nanocomposite material and its application. More specifically, the solution concerns: nanocomposite packaging material, the active material of which is zeolite exchanged with silver ions bound in the form of silver cations; as well as the use of nanocomposite material for packaging works of art, archives and monuments, as well as food, plants, pharmaceuticals and animal feed.

The literature on the subject indicates that silver ions have both biostatic and biocidal properties, with a low toxicity (compared to other transition metals) towards higher organisms.

From European patent EP 0297538 B1, (publication date: June 29, 1988), a film containing zeolite with biocidal (antibiotic) properties is known. The patent describes a zeolite containing a polymer film with biocidal properties, where the zeolite content is minimized. The film is applied to at least one side of the polymeric support.

The international publication WO 2006/046837 A1, (publication date: May 4, 2006) discloses a method for the preparation of zeolite-fiber composite substrates. The application describes a method for preparing zeolite-fiber composites, and the subsequent steps involve reacting the fibers or zeolite with a binder to form an intermediate, and then using sonication to react between the intermediate and the remaining zeolite or fibers to form a composite material.

A biocidal (antibiotic) zeolite is known from the European patent EP 0270129 B1 (date of publication: April 12, 1987). The patent describes a biocidal zeolite and a resin containing either the zeolite or the biocidal zeolite. All natural and synthetic zeolites are described, including silver ions (0.1-15%), copper and / or zinc ions (0.1-8%) and ammonium ions (0.5-15%). Other heavy metals may also be mentioned in the zeolite and the described resins include the entire body of thermosetting and thermoplastic resins.

The international publication WO 01 / 94512A1 discloses a method of partial substitution (in the amount of 2-40 wt.%) Of the metal atoms (M) of the zeolite of formula M2 / n * AhO3 * xSiO2 * yH2O by a metal from groups III, IV and Mg, Ti, Cr , Fe, Ni, Cu, Zn, Zr, Ag, the metal mixed with the zeolite in the form of an aqueous solution of the salt of this metal, and the pH of the solution is in the range of 4-10.

The international publication WO 2007037195A1 describes an antibacterial zeolite in which the exchange ions are partially or completely replaced by hydrogen and silver ions. The solution concerns a resin-based material filled with hydrogen zeolite substituted with silver cations.

Publication TW 201215561 A discloses a zeolite with modified mechanical properties extending its service life. The zeolite has been substituted with copper and silver cations, which is aimed at cheaper production costs while maintaining microbicidal properties similar to purely silver. The modification consists in the optimization of the Si to Al ratio and the use of structural additives in the form of zirconium phosphate and gelling agents.

Chinese patent application CN 102452664 A relates to a zeolite material with a modified structure by adding ash, zirconium phosphate and refractory mortar and by optimizing the Si to Al ratio. in the zeolite itself. The zeolite contains silver and copper ions to maintain similar microbicidal properties at lower cost.

The techniques offered on the market are also known: MicroChamber and Artcare paper products containing zeolites in their structure that can remove exo- and endogenous gaseous pollutants from the microenvironment of historic buildings. MicroChamber paper, however, does not contain any zeolites containing exchanged metals or metallic nanoparticles. This type of paper also has no antimicrobial activity.

The EKOPAK-plus company produces packages with a special coating of silver nanoparticles. This coating protects the products against the growth of microorganisms (bacteria, viruses and fungi) during transport and storage. Nanosilver inhibits the enzymatic processes of bacteria and contributes to the formation of active oxygen in water and air, which effectively prevents the growth of microorganisms.

As it results from the presented literature and the state of the art, there is still a need for intensive work on the search for packaging materials that would differ from those currently available in many features, including multifunctional nature, and have properties limiting the migration of silver particles from the packaging to the packed object. .

PL 228 387 B1

The aim of the invention is to provide a packaging material with high biocidal activity and sorption properties with a minimum amount of silver introduced into the zeolite, which silver would be in a state of atomic dispersion (and not in the form of clusters or nanoparticles), i.e. in the form of ions firmly attached to the zeolite matrix to prevent their migration.

The subject of the invention is a nanocomposite material with antimicrobial properties based on cellulose filled with a mineral filler (zeolite) substituted with silver cations, characterized in that the mineral filler is Y type zeolites, while silver is in a form bound to the zeolite matrix in the form of cations, the silver content is in the range from 1 to 2% by weight, and the material, apart from antimicrobial properties, also shows sorption and catalytic properties.

In the material according to the invention, silver ions have preferably been introduced into the zeolite structure by ion exchange.

The solution according to the invention is a multifunctional nanocomposite material based on cellulose filled with a zeolite substituted with silver cations, showing antimicrobial properties, which can be used, among others for wrapping plants (live and cut flowers), food and pharmaceuticals, pet food, works of art and antiques, and as insulation material. The main problem in using the biocidal properties of silver is the migration of its nanoparticles to the protected object (food, organisms). The harmfulness of nanoparticles to the biosphere is still the subject of scientific disputes, and the content of silver nanoparticles in food and packaging is not currently regulated in the European Union or the United States of America. Studies show that silver nanoparticles have similar biostatic and biocidal properties to solutions containing silver ions or suspensions of silver microparticles. Thus, an issue that must be considered is the possible release of silver ions from the developed material into the environment. If such a phenomenon occurred, the present invention could be qualified under the existing regulations and regulations regarding the presence of silver ions in food / drugs, etc.

Preferably, in the material according to the invention, the zeolite matrix is free of silver in an unbound form in the form of silver oxide clusters.

The solution according to the invention uses a Y-type zeolite (mesoporous material with a fotosite structure) as a carrier for silver. Foyzyite is a fairly rare mineral, but it is synthesized in industry on a large scale. During ion exchange of the sodium form of the zeolite, sodium cations are replaced with silver cations (silver bound state), but it is also possible to deposit silver oxide crystals on the zeolite outer surface (silver unbound state). Thus, upon treatment with a solution of a silver salt in the zeolite, there is both a bound form of silver in the form of cations and an unbound form of crystallites (clusters) of its oxide. The invention provides a method of eliminating silver in the form of clusters from the zeolite surface to obtain pure zeolite substituted with silver cations, i.e. a material with silver in a bound state. As a result, the risk of silver contamination of the packaged products and the external environment is reduced.

The material according to the invention preferably exhibits sorption properties against volatile organic compounds and gaseous pollutants. The material according to the invention is particularly preferably characterized by sorption properties against both (VOC) and gaseous pollutants such as SO2 or NOx. The zeolite used in the present invention has a gas sorption capacity and has been shown to be effective as a component in other products as a material that reduces the concentration of volatile organic compounds (VOCs) and other odor-related gases, e.g. resulting from the degradation of stored materials.

Additionally, the silver inside the zeolites can be a catalyst for the oxidation of VOCs. Therefore, the material according to the invention preferably exhibits catalytic properties and promotes the self-degradability of the packaging material.

In this way, the present invention is new compared to other zeolite-containing cellulosic materials in that it can remove gases both by sorption and potentially by catalytic decomposition.

The material according to the invention has proven biostatic and biocidal properties against both bacteria and fungi. The material according to the invention has been shown to have beneficial bactericidal properties against Escherichia coli, Serratia marcescens, Bacillus suhtilis and Bacillus megatherium bacteria as well as fungicidal properties against Trichoderma viride, Chaetomium globosum, Aspergillus Niger, Cladosporium cladosporides, and Morterelpinum.

PL 228 387 B1

The solution according to the invention differs from the presented solutions from the prior art by the use of zeolites with silver cations bound in their structure. The use of zeolites has a stabilizing effect on the obtained material. In particular, one should consider limiting the migration of silver nanoparticles (accumulated in the packaging material) to objects or substances stored in the packaging. Silver nanoparticles can catalyze many reactions, including oxidation reactions, which can ultimately lead to the destruction of the packed object. The inventive solution differs significantly from the prior art products in that, due to the use of silver-substituted zeolites, the inventive material is a multifunctional paper product that absorbs contaminants and exhibits antimicrobial properties.

Another subject of the invention is the use of a nanocomposite material with antimicrobial properties based on cellulose filled with a mineral filler (zeolite) substituted with silver cations, characterized in that the mineral filler is Y type zeolites, while silver is in the form bound to the zeolite matrix in the form of cations, silver content ranges from 1 to 2% by weight for packaging.

The inventive material can advantageously be used as a packaging material for storing works of art, archives and antiques, as well as food plants, pharmaceuticals and animal feed.

The market for active multifunctional materials is a growing market. Consequently, there are clear fields in which the present invention can find versatile application. Due to the nature of the material according to the invention, it is advantageous for the material according to the invention to find customers in libraries, archives and museums, in particular as packaging material for works of art and archives. It is worth noting that currently the interest of the societies of developed countries in preserving cultural and archival heritage is increasing, as evidenced by a number of programs adopted by the EU and the Americas that finance both activities and research in this field.

The solution according to the invention can be used in the area of securing works of art and monuments. The material according to the invention can be part of cardboard elements in contact with a work of art, particularly for fixtures that will come into contact with the exterior walls of buildings. During winter, exterior walls, especially in poorly insulated buildings such as historic houses and churches, can become cold, creating a moist microclimate inside the building. This is a particularly dangerous situation in the spaces behind and between the objects of interest, where the risk of mold growth increases. The solution according to the invention, prepared in the form of a cardboard and used as a mounting support or as a back wall for an object in a frame, can serve as a preventive tool to limit the growth of mold. As a result of increased humidity, water bridges will form between the cardboard board and our facility, which should further strengthen the biostatic effect. Another application in this group may be the use of the material according to the invention for wrapping materials of organic origin (fabric, leather, parchment, paper, wood, fossils etc.) which may also be susceptible to microbial attack. The tissue paper material of the invention may also be prepared and delivered as a ready-made kit for use in the event of a disaster such as a flood or flooding. For these types of disasters or breakdowns, wet items are often blotted and wrapped in wipes prior to vacuum packing. In the next step, items are kept at a low temperature, which inhibits or significantly reduces microbial growth. The use of the material according to the invention, in contrast to conventional tissue paper, offers the possibility of additional antimicrobial protection. In all the cases illustrated, the sorption properties of the material according to the invention are also of importance. For the storage of archives or library collections, boxes or envelopes made of the material according to the invention with these sorptive and biocidal properties can be used.

In protecting works of objects of cultural value, it is necessary to cut them off from the influence of gaseous harmful air pollutants, such as acid gases present in high concentration in urban agglomerations (NOx, SO2, CO2), as well as to remove gaseous products of its degradation from the atmosphere surrounding the object, which also often have a destructive effect on the object. The undesirable effects of microorganisms (molds and bacteria) on works of art are known and described many times in the literature on the subject.

PL 228 387 B1

The use of the material according to the invention, which combines antifungal, antibacterial, biocidal and biostatic properties and at the same time has sorptive properties as a protective packaging, gives a unique possibility of comprehensive protection of various types of objects, especially historic and archival ones, against damage caused by various factors.

According to the inventors' knowledge, the present solution is the only currently known product that combines various desirable features and enables universal application. The stabilizing properties, multi-functionality, the use of renewable materials, simple and scalable production methods and the approach in line with the "green chemistry" trend distinguish the present invention from other products commercially available on the market.

The material according to the invention has been subjected to comprehensive physicochemical tests. They show, among others, that silver ions substituted in zeolite to the mineral filler are permanently bound to it and do not penetrate into the environment, which is important due to the invariability of the biostatic properties of the material and the safety of its use. The tests for the presence of silver ions in the aqueous filtrate, which were in contact with the processed material (the sample marked P_ZAg0 was used) gave a negative result - neither cold nor hot, no silver ions were extracted into the water, which was confirmed by the test with chloride ions and XRF measurement.

The transfer of silver nanoparticles and silver ions during contact with model food can be checked using appropriate analytical techniques. In the tests that the authors of the application performed using the XRF technique, no silver was found on agar media in long contact with silver-containing paper discs.

The results of the physicochemical analyzes of the material according to the invention are shown in Figures 1-7, in which

Fig. 1 shows the quantitative characteristics of the sorption of silver cations during zeolite ion exchange in the form of a silver ion sorption isotherm prepared on the basis of the quantitative analysis performed by means of XRF;

Fig. 2 shows the results of quantitative and qualitative analyzes of the zeolite material in the form of an XPS spectrum with a marked band on which the optimization of leaching of unbound silver was based;

Fig. 3 shows the concentration of silver in the final material and in the reference samples;

Fig. 4 shows the stability of the paper material as determined by measuring the pH of the samples at various stages of the preparation as well as the reference samples;

Fig. 5 shows the durability of the paper material after aging tests performed according to the ASTM standard and expressed as the degree of polymerization of cellulose;

Fig. 6 shows the results of microbiological testing for bacteria;

Fig. 7 shows the results of microbiological tests for fungi.

The invention is illustrated in more detail in non-limiting examples.

P r z k ł a d 1

Ion exchange of zeolite

In the first stage of material preparation optimization, the silver sorption isotherm from 0.1 M aqueous silver nitrate (V) solution was determined. For this purpose, 0.50 ± 0.01 g of CBV100 zeolite was weighed and transferred quantitatively to an Erlenmeyer flask, and then flooded (100 ml) with the previously prepared 0.1 M silver nitrate solution. The suspension was shaken at 300 rpm at 23.5 ° C and then filtered on a quality funnel (paper filter). The precipitate was washed with 150 ml of distilled water and dried at 60 ° C. The dried sediment was weighed and the water content was determined at 200 ° C - the water content was determined using a moisture analyzer (HR.83 - Mettler Toledo).

The precipitate was quantitatively transferred to a beaker and quenched with 10 ml of nitric acid, heated to boiling and kept at reflux for 20 minutes. The suspension was cooled to room temperature, transferred to a thimble and centrifuged (2000 rpm, 4 min time) with a centrifuge (MPW-223e). The supernatant solution was quantitatively transferred to a 25 ml volumetric flask. The sediment in the thimble was covered with distilled water (approx. 3 ml), shaken by hand for 30 seconds, and then the centrifugation procedure was repeated (5 times), each time transferring the supernatant solution to the same volumetric flask as the first time. The solution was made up to the mark (Vr-ru = 25 ml). The sediment remaining in the thimble was dried and secured in order to check the effectiveness of the silver leaching.

PL 228 387 Β1

a) Determination of silver in zeolite by X-ray fluorescence spectroscopy (XRF)

Measurements were made using an ED-XRF (Quant'x - Thermo) spectrometer. Measurement parameters: t = 60 s, measurement in an oxygen atmosphere, thick copper filter, large measuring cup. The Kot line for silver was selected for the determination (integrated with background cut-off in the range of 21.46-22.60 keV). The determination of silver was carried out in solutions with zeolite dissolved in HNO3 and the results are presented in Table 1. The determination of the silver content is affected by a 5% error, determined on the basis of the reference to the blank. Problem results from the scatter of the - correlation coefficient for fitting the calibration curve prepared on the basis of analysis of the standard solution of AgNO3 (see Table 1) is R ² = 0.9819. The error is also brought about by incomplete elution of silver from the zeolite with hot HNO3.

The content of silver in the part of undissolved zeolite in the form of sediment was also checked, but the amount of silver in the sediments did not exceed 1% by weight. For this reason, determinations of silver content in zeolite were based on analyzes of dissolved material.

Table 1.

XRF test results for silver content in solutions after washing with hot HNO3. Z_Ag ⁺ - silver-substituted Y zeolite; index 0.1 in the sample name means the concentration of AgNC> 3 solution during ion exchange; the next index in the name means the ion exchange time in h.

Mark Number of counts Silver content [mg Ag / g zeolite] Zeolite analysis Z_Ag ⁺ _0.1_l 280 009 94 Z_Ag ⁺ _0.1_2 429 447 263 Z_Ag ⁺ _0.1_3 422 800 253 ZAg ⁺ 0.1_2 () 396 006 246 Z_Ag * _0.1_29 423 703 265 Z_Ag ⁺ _0.l 39 374 803 225 Z_Ag ⁺ _0.I_92 439 191 254 Data for the calibration curve 0.1 M AgNOj 681 895 - 0.05 M AgNOj 430 140 - 0.033 M AgNO ₃ 365 614 - 0.025 M AgNO, 298 052 - The determined concentration [moI / LJ Blank 0.05 M. 424 895 0.0475

Based on the obtained results (Table 1), the silver sorption isotherm was determined. The appropriate silver content converted to the mass of zeolite was calculated in relation to the calibration curve (Fig. 1). The results showed that the half exchange of zeolite with silver ions under the described conditions is achieved after approx. 1 hour. (fig. 1)

PL 228 387 Β1

b) Preparation of the zeolite matrix

On the basis of the determined sorption isotherm, 1 hour was selected as the optimal time of ion exchange. Three portions of 5.00 g each were weighed. The first portion was placed in a beaker and quenched with 100 ml of 0.1 M aqueous silver nitrate solution. The suspension was shaken for one hour at 300 rpm. The precipitate was filtered off and the recovered nitrate solution was reused for sorption for the second and third batches. The pellets were rinsed with 500 ml of distilled water to wash out excess silver nitrate. After the pellets were dried at 60 ° C, they were mixed to obtain a homogeneous sample. From the thus prepared basic material, a representative sample was collected in order to perform physicochemical analyzes (the results are presented below). The base material (silver exchanged zeolite) was used as a filler for paper sheets in the further preparation.

Example 2

Modification of the structure and composition of the zeolite matrix

Before applying the procedure for removing silver ions from the outer surfaces of zeolite crystallites, the effect of washing on sample dealumination was checked. For this, reference samples of crude zeolite were washed with an aqueous solution of disodium ethylenediaminetetraacetic acid (EDTA). The procedure consisted of three stages:

a) washing the zeolite on a funnel (paper filter) with 150 ml of 0.01 M EDTA solution (room temperature),

b) rinsing at boiling point with 150 ml of 0.01 M EDTA solution (holding time -1 hour),

c) washing with 150 ml of 0.1 M EDTA solution.

The rinsing was carried out in a quality funnel with the use of quality paper points. The appropriate solutions were dosed in such a way that the sediment was immersed in the solution throughout the washing period. The sediment was washed with a fresh portion of complexone each time - no recirculation of solutions was used. In the case of hot washing, the modified material was placed in a beaker and poured with 0.01 M EDTA solution. The solution was stirred with a magnetic stirrer and kept at reflux for one hour.

a) Exclusion of zeolite dealumination

The filtrates were centrifuged (4000 rpm, 4 min) and then characterized by ASA atomic absorption spectrometry (Zeeman Z 2000 polarized atomic absorption spectrometer, HITACHI) to eliminate the possibility of zeolite dealumination during leaching. Table 2 shows the results of tests performed on the filtrates after treatment of zeolites with Na2EDTA.

Table 2.

Results of the determination of aluminum in the filtrates after EDTA washing.

EZ1-EZ3 - consecutive zeolite samples were treated as shown in the table.

Mark Treatment method Occurrence aluminum in the filtrate | j.u.] NMR signal for dried sludge ϋ · «·] EZ1 Cold 150 ml 0.01 M EDTA not detected (1) 1.0204 EZ2 Cook for one hour in 0.01 M EDTA detected (33) 0.9979 EZ3 Washed with 150 ml of 0.1 M EDTA not detected (1) 1.0370

PL 228 387 Β1

The fact that no aluminum was detected in the solutions does not mean that there is no dealumination in the zeolite network, hence the material characteristics have been extended to include ²⁷ AI MAS NMR studies. For this purpose, the dried pellets after washing with an aqueous EDTA solution were tested for changes in the aluminum NMR signal. Normalization was performed to the surface area of the main signal for the unmodified tetrahedral aluminum starting zeoliote Y (A = 1.0000). The values for the measured samples are also given in Table 2. The obtained results indicate that the conducted process does not cause dealumination. This proves that the zeolite structure is maintained in the further preparation stages.

b) Optimization of the zeolite washing process

In addition to checking the presence of dealumination, the amount of 0.01 M EDTA solution necessary to complex the silver in the form of an oxide on the outer surfaces of the zeolite grains was determined during the preparation. The washing procedure was the same as for the determination of the degree of dealumination. During the silver leach, in addition to treating the silver ion exchanged zeolite with EDTA solution, it was rinsed with deionized water to remove excess complexing agent. Leaving EDTA in the zeolite volume caused changes in the zeolite structure during drying, which manifested itself in a significant color change (to green, and later to black). No such effect was observed after the rinse with deionized water was applied.

Optimization of the concentration and quantity of the EDTA solution used to wash the Ag ⁺ cation substituted zeolite samples was performed on the basis of XPS analyzes for the Ag ⁺ band in the XPS spectrum with a binding energy of 432 eV (Fig. 2). Table 3 shows the results of the quantitative analysis of modified zeolite samples (symbols mean, respectively: Z_Ag + means zeolite substituted with silver ions, not rinsed, Z_Ag + _H2O - zeolite substituted with silver ions, washed with deionized water, Z_Ag + _0.01 M_EDTA_150 - zeolite substituted with silver ions 150 ml 0 rinses , 01 M EDTA and water, Z_Ag + _0.01M_EDTA150 - zeolite substituted with silver ions, rinsed with 150 ml 0.1 M EDTA and water, Z_Ag + _0.01M_EDTA_300 - zeolite substituted with silver ions, rinsed with 300 ml 0.01 M EDTA and water.

The results show that increasing the EDTA concentration from 0.01 M to 0.1 M for the samples Z_Ag + _0.01M_EDTA_150 and Z_Ag + _0.1M_EDTA_150, respectively, resulted in further leaching of silver from the zeolite. In order to minimize the amount of silver, a more concentrated EDTA solution was used for further washing tests. On the other hand, an increase in the amount of washing solution from 150 to 300 ml for the samples Z_Ag + _0.1M_EDTA_150 and Z_Ag + _0.1M_EDTA_300, respectively, does not cause further leaching of silver, and the differences in the determined amounts of Ag ⁺ are within the measurement error.

Table 3.

Quantitative results for silver on the surface of crystallites after washing with EDTA.

A sample Washing [ml] XPS signal for silver after normalization [j.u.] first the second AgY - - 1.05 Z_Ag + _H ₂ O 150 H ₂ O 150 H ₂ O 1.19 Ż_Ag + _0.01 MEDT A 150 150 EDTA 150H ₂ O 1.25 Z_Ag + _0, lM_EDTA_150 150 EDTA 150 HzO 0.29 Z_Ag + _0.1 MEDTA300 300 EDTA 150 H ₂ O 0.31

Example 3

Development of a method of forming paper sheets filled with zeolite

The paper samples were prepared by disintegrating 4.00 g Whatman filter paper in 400 ml of distilled water using a homogenizer (IKA T18 Ultra-Turrax). Depending on the type of the prepared sample, an appropriately prepared active material was added to the pulp prepared in this way (Table 4).

PL 228 387 Β1

Table 4.

The method of preparing model samples of packaging material.

Mark Active material The method of preparation of the active material - addition to the paper pulp P. Lack Not applicable PAg + Silver ions 0.51 g of silver nitrate (V), corresponding to 0.003 mol Ag in the volume of the material PZO Zeolite Y 1.77 g of unmodified Y zeolite PZAg + Zeolites exchanged with silver ions 1.77 g of zeolite exchanged with silver ions according to the methodology described. PZAg + EDTA Zeolites exchanged with silver ions - washed with EDTA 1.77 g of zeolite Y exchanged with silver ions washed with 530 ml 0.1 M EDTA solution and 250 ml of water distilled

The prepared furnish as described in Table 4 was formed into sheets of paper with a papermaking machine connected to a suction system. A hydrophobic fabric was used as a supporting element for the drained paper pulp. The sheets were dried on the glass in a room atmosphere. The samples were cut from the dried paper sheets in the form of disks 6 mm in diameter. The samples were secured by placing them in paper envelopes. The samples were disinfected at the stage of microbiological tests.

a) Determination of the concentration of silver in paper sheets

During the optimization of the silver content in the final material, the quantitative analysis was synchronized with the microbiological analysis in order to determine the minimum amount of silver in the paper that guarantees satisfactory biocidal activity. Table 5 shows the microbial activity against the tested model organisms.

Table 5.

Microbiological activity of paper materials with different silver content for selected test organisms.

Silver content mg Ag / g paper Bacteria Mushrooms 87 + + + + 46 + 10 + + 1 + + - / -

The silver content was determined according to the following procedure:

0.02 g of paper is weighed, about 7.5 ml of 65% nitric acid (V) are poured in and brought to the boil. The slurry was held at reflux for 15 minutes while stirring. The suspension was quantitatively transferred to a tube and centrifuged at 4000 rpm. The supernatant solution was quantitatively transferred to a 25 ml volumetric flask. The sediment in the test tube was covered with water

PL 228 387 Β1 distilled, mixed to a suspension, then centrifuged again. The procedure was repeated four times. The solution in the flask (after the end of the procedure) was made up to the mark. These solutions were the basis for the determination of silver by means of XRF.

The concentration of silver in the prepared samples was determined by the XRF method from the calibration curve. The results are presented in Fig. 3 and the percentages are presented in Table 6.

Table 6.

Percentage of silver in the final material and in the reference samples

A sample Mg Ag content / g paper % Silver in the paper PAg + 2.69 0.3 PZAg + 14.9 1.5 PZAg + _EDTA 10.9 1.1

b) Durability of the resulting paper material

One of the parameters determining the durability of the paper is its pH. The pH measurements of the paper samples were made with a flat electrode (Flatrode Hamilton, 809 Titrando - Metrohm). Samples and a drop of water were cut from the prepared paper sheets. Then the flat electrode was placed on the sample and the pH was measured until stabilization was achieved (not less than 120 s). The measured pH values are shown in Figure 4.

Another parameter determining the durability of the paper may be its grade after aging tests. The conditioning of the samples was performed according to ASTM D685 at 23 ° C and RH = 50%. The procedure described in ASTM D6819-02 (2007) was used for the aging tests. Aging was carried out in a climate chamber at 90 ° C and 59% relative humidity. The samples were aged for 12 days. Both pure cellulose and zeolite papers have been aged.

The degree of weight average polymerization (DPw) of cellulose in the form of cellulose triphenyl carbamate (CTC) was determined. Molecular weight distribution analysis was performed in tetrahydrofuran, with dual detection: multi-angle light scattering (MALLS) and refractometric (RI) detection. Both detectors operated at a wavelength of 658 nm. The measurements used the value of a specific refractive index increment equal to 0.162 ml / g, determined experimentally on the chromatographic set, on which subsequent measurements of the molecular weight distributions of the material were performed.

The cellulose material with the zeolite was subjected to the normal sample preparation procedure as described above, the zeolite was separated from the CTC solution by filtering the solution through a 0.45 μπι Teflon syringe filter. The filtered solution was subjected to further SEC analysis.

Paper with silver ions / nanoparticles and silver ions / nanoparticles and zeolite before derivatization was rinsed to remove silver ions / nanoparticles to avoid contamination of the chromatography column. Paper samples containing AgO, Ag + and zeolite were defibrated in a beaker with 50 ml of water (the process was assisted by an ultrasonic bath).

The results of DPw measurements of aged and reference samples are presented in Figure 5. The results show that the presence of zeolite substituted with silver cations causes faster degradation of the paper. However, the smallest degradation effect was observed for the target zeolite sample washed with the ESTA - PZAg + _EDTA solution. The result indirectly indicates the catalytic properties of the materials obtained. The faster degradability of zeolite materials has value in considering packaging materials to self-decompose in nature.

Example 4

Determination of the microbial activity of paper material with a modified zeolite filling

The tests were performed using the following test organisms:

PL 228 387 B1

1. Escherichia coli

2. Serratia marcescens

3. Bacillus subtilis

4. Bacillus megatherium

5. Trichoderma viride

6. Chaetomium globosum

7. Aspergillus niger

8. Cladosporium cladosporioides

9. Mortierella alpinum

The above strains are stored on media at the Laboratory of the Plant-Microorganism Interaction Team, Institute of Environmental Sciences, Jagiellonian University (Krakow) and are used for comparative studies after inoculation on appropriate media. Some of these strains come from paper isolation and some were obtained during other types of research.

Samples of materials prepared at the Faculty of Chemistry of the Jagiellonian University were used for the test. These samples were sterilized on Whatman paper in Petri dishes before being used in the experiment.

Bacteria (strains 1-4) were spread on the agar surface (NA) and spread with a disposable stick (a single stick was used for a given strain). For each of the strains and each type of paper test, 3-5 replicates were used (some of the replicates were rejected due to uneven application of the material, which is visible after a few days from the time of the test; min. N = 3). A single disc of paper was placed on each Petri dish containing the bacteria. The cultures were placed at 32 ° C for three days and then the temperature was lowered to 25 ° C for a further few days. The growth of microorganisms was observed daily.

No zone of no growth was found around the disc material in any of the cases tested. The rest of the experiment was transferred to a laminar chamber (sterile conditions). A significant reduction in bacterial growth was found under the discs with the addition of silver (in any form). Each of the Petri dishes was opened, and a disc of paper was placed on the back of the upper dish with sterile tweezers, turning it upside down and thus exposing the part that adhered to the agar. To assess the number of bacteria, the LuciPac Pen test (ATP + AMP Hygiene Monitoring test kit by Kikkoman Corp. code 60331) was used, following the recommendations with minor innovations. The swab was positioned perpendicular to the disc in the central part, and resting the tip in the "screwdriver" position was turned 360 °. The result defining the relative ATP + AMP content was then read on a lumitester reader.

Mushrooms (strains 5-9) were introduced into Petri dishes containing PDA medium and three filters of each type were placed centrally. In each case, three repetitions were assumed. The strains were introduced as an agar disc with mycelium 2 cm from the center disc. Due to the different growth rates of the mycelium, it was necessary to conduct the test for a longer period (approximately 2 weeks). Each of the tested strains showed slightly different problems during the observation.

Trichoderma viride - the strain formed colonies with spores in the circular area of the colony outside; in some cases the disc fell out of place, making observations difficult. In a few cases, delayed maturation of conidia in the form of light green or yellow conidiophores (outside this area of blue-green conidia) was observed.

Chaetomium globosum - fruiting body formation was generally delayed on the surface of the paper samples used where the mycelial activity was probably concentrated on the decomposition of the paper, while fruiting was a sign of a lack of nutrients.

Aspergillus niger - well suited for quick tests, although as the test passed, spores released from the surrounding conidiophores appeared on the surface of the silver discs, which made the analysis somewhat difficult, but such conidia did not germinate in such places, although they probably remained viable.

Cladosporium cladosporioides - species characterized by relatively slow growth; it was necessary to reapply the inoculum to the dishes to speed up the moment when the mycelia would reach the disks; the advantage of this species is the production of black mycelium visible within the paper discs in cases where the colonization of the paper took place.

Mortierella alpina - light mycelium with conidia devoid of dark pigments.

The results presented in Figures 6 and 7 show that the paper filled with zeolite substituted with silver cations PZAg + EDTA has the best microbicidal properties. Taking into account four parameters: silver content in paper preparations, durability of the paper (not indicated), number of stages during

The most optimal material is paper filled with silver cation substituted zeolite PZAg + EDTA. Based on the optimization of silver content, a material containing 1% (w / w) silver was selected for physicochemical tests. This is the lowest value for which biocidal activity was observed in relation to all tested organisms.

Claims (11)

Patent claims 1. Nanocomposite material with antimicrobial properties, based on cellulose filled with a mineral filler (zeolite) substituted with silver cations, characterized in that the mineral filler is Y-type zeolites, and silver is in a form bound to the zeolite matrix in the form of cations, the silver content is in the range from 1 to 2% by weight, and the material, apart from antimicrobial properties, also shows sorption and catalytic properties. 2. The material according to claim The process of claim 1, wherein the silver ions are introduced into the zeolite structure by ion exchange. 3. The material according to p. The process of claim 1, wherein the zeolite matrix is free of silver in unbound form in the form of silver oxide clusters. 4. The material according to p. The method of claim 1, characterized in that it exhibits sorption properties towards volatile organic compounds and gaseous pollutants. 5. The material according to p. The method of claim 1, characterized in that it exhibits catalytic properties and promotes the self-degradability of the packaging material. 6. The material according to p. The method of claim 5, characterized in that it exhibits bactericidal properties against Escherichia coli, Serratia marcescens, Bacillus subtilis and Bacillus megatherium. 7. The material according to p. The method of claim 5, characterized in that it exhibits fungicidal properties against the fungi Trichoderma viride, Chaetomium globosum, Aspergillus Niger, Cladosporium cladosporides. 8. The material according to any of the preceding claims, characterized by bactericidal and fungicidal properties. 9. Use of a nanocomposite material as defined in claims 1 to 8 as a packaging material. Use according to claim 1 9 for packaging plants, works of art, archives and antiques. 11. The use according to claim 1 9 for food, pharmaceutical and pet food packaging.