WO2008064750A2

WO2008064750A2 - Antimicrobial resin materials and method of manufacturing the same

Info

Publication number: WO2008064750A2
Application number: PCT/EP2007/009228
Authority: WO
Inventors: Jung H. Cho; Karl-Hans Leyrer
Original assignee: Polytech & Net GmbH
Current assignee: Polytech & Net GmbH
Priority date: 2007-10-24
Filing date: 2007-10-24
Publication date: 2008-06-05
Anticipated expiration: 2010-04-24
Also published as: WO2008064750A3

Abstract

The present invention relates to an anti-microbial resin composition comprising uniformly distributed functional particles in an amount of 0,1 % to 99% by weight of the anti-microbial resin composition, wherein the functional particles comprising a metal oxide and/or ceramic nano-particle core with a diameter of 5nm to 100nm and anti-microbial metal nano-particles with a diameter of 0,5nm to 10nm, wherein the anti-microbial metal nano-particles are fixed onto the surface of the metal oxide and/or ceramic nano-particle core and a method for preparing the resin composition.

Description

ANTIMICROBIAL RESIN MATERIALS AND METHOD OF MANUFACTURING

THE SAME

FIELD OF THE INVENTION

The present invention relates to anti-microbial resin materials and a method of manufacturing the same, and more specifically, to an anti-microbial synthetic- resin material which could be produced in master batch, powder and liquid form, which has an anti-microbial function and a method of manufacturing the same.

BACKGROUND OF THE INVENTION

There have been efforts to apply the functions of functional nano-particles to a variety of industrial fields by using silver, gold or platinum nano-particles with a diameter of several to dozens nanometers.

However, when the functional nano-particles are simply applied, the function thereof may be degraded by oxidation, discoloration, cohesion and precipitation of the nano-particles. Further, the functional nano-particles may irregular dispersed in a resin that can result in a conglomeration of the nano-particles. This makes it difficult to apply the functional nano-particles to achieve uniform properties in the resulting compounds.

In conventional methods, to impart functionality to various products such as textiles or containers using synthetic resins, the following methods are taken: a) functional nano-particle solution or stabilized powder is mixed with resin directly before extrusion (Korean patent registration no. KR10-0609596) or b) mixed with grains of resin to coat the resin surface with the functional nano- particles (Korean patent registration no.10-0702848) or c) directly coated on to application such as textiles, filament, non woven, etc.

(Korean patent registration no. KR10-0753752-0000). Then, the materials are used to manufacture synthetic resin products, such as textiles and containers in a way that the functionality is imparted to the products. However, oxidation of the functional nano-particles due to heat treatment of the synthetic-resin products can occur. Accordingly, oxidation may decrease functionality of the nano-particles in particular in view of the anti-microbial properties of the resin compounds. In addition the nano-particles are often not uniformly dispersed in the resin due to aggregation of the particles. Therefore, the functionality, including anti-microbial properties, is only existing in those parts of the compound where nano-particles are aggregated but does not exist in the other parts where the nano-particles are not present.

Furthermore the aggregation of the nano-particles in the resin compound could cause problems in view of its mechanical properties. For example, while nano- particles included in synthetic-resin products such as filaments are being manufactured, the filament can break easily in the parts where the nano- particles are aggregated.

In US 6,121 ,346 a rubber composition containing a filler having aggregates of small and large particles is described wherein the small particles are grafted onto the surface of the large particles to improve the distribution of the filler in the rubber material. WO 2005/049489 describes a particle composite made of a carrier surrounded by a layer made of oxidic material having an irregular surface wherein small active particles are fixed onto the surface of the coated particles. The described particles can be used as filler material in polymers to improve the mechanical properties or to reduce the amount of active materials distributed in the resulting compounds.

Objects of the present invention are to provide improved resin compounds for a homogeneous distribution of functional particles in particular to improve the antibacterial properties of the resulting resin compounds comprising the functional particles. A further object of the present invention is to prevent yellowish or khaki coloring of the resin which occurs usually due to silver or gold or platinum nano-particles and to facilitate mixing resin and nano particles preventing possible oxidization or aggregation of nano particles.

SUMMARY OF THE INVENTION

The present invention relates to an anti-microbial resin composition comprising particles with anti-microbial function (herein called "functional particles"). A functional particle comprising a metal oxide nano-particle core and/or ceramic nano-particle core with a diameter of 5nm to 100nm and anti-microbial metal nano-particles with a diameter of 0,5nm to 10nm, wherein the anti-microbial metal nano-particles are fixed onto the surface of the metal oxide and/or ceramic core nano-particle. The functional particles are suitable for an improved distribution in the resin. The above-mentioned diameters are average diameters values (D50) which can be determined e.g. by thermal-electron-microscopy (TEM).

The anti-microbial resin composition could be produced e.g. in form of a dried concentrate (e.g. for production of a master batch composition), in form of a master batch, powder, finished resin or end-product or in form of a liquid wherein the components are dispersed or solved in a solvent. Consequently the term anti-microbial resin composition encompasses solid and liquid compositions comprising the resin and the functional particles.

The amount of functional particles present in the anti-microbial resin composition is from 0,1% to 99% by weight of the solid compounds (that means of the dried anti-microbial resin composition or without the solvent if the composition is present in its liquid form), preferred between 40% and 80% if a anti-microbial resin composition concentrate is prepared, preferred between 1% and 50%, in particular between 4% and 40% for master batch compositions and preferred between 0,1% to 5%, in particular between 0,4% to 2% for finished resins or end-products. The metal oxide nano-particle cores respectively the ceramic nano-particle cores are preferred selected from a group consisting of silicas, like silicon dioxide, alkali metal or earth alkali metal oxides, in particular magnesium oxide and calcium oxide, zirconium oxides, aluminum oxides, scandium oxides, yttrium oxides or titanium oxides or nitrides, borides, carbides, chalcogenides or silicates of these metals or mixtures thereof. Preferred core nano-particles are zirconium dioxide or titanium dioxide. E.g. zirconium dioxide (zirconia) is a ceramic material that is used preferred in pure form but it can be also applied in combination with other oxides like magnesium oxide, calcium oxide, yttrium oxide or cerium oxide.

The used core nano-particles have preferred a surface in a range between 10 square meters / gram and 400 square meters per gram, in particular between 10 square meters / gram and 200 square meters / gram (BET, Journal of American Society, Volume 60, page 304 (1930)).

For the preparation of the core nano-particles the metal oxide respectively the ceramic compound can be dispersed in an organic solvent using an organic dispersing agent while breaking the metal oxides or ceramic compounds such as zirconium oxide into nano-particles in particular by attrition, pyrolysis or milling, using for example a ball mill. Preferred dispersing agents are acrylic polymers or organic silicates, e.g. tetraethyl orthosilicate (TEOS). The used core nano-particles have a diameter of 5nm to 100nm, preferred between 20nm and 40nm, which can be reached for example by mechanically treating the raw material with a ball mill. The treatment may comprise mechanically breaking the raw material into core nano-particles. In a preferred embodiment at least 70%, in particular at least 90% of the core nano-particles distributed in the antimicrobial resin fall into the mentioned diameter range.

The anti-microbial metal nano-particles are preferred selected from the group consisting of silver, gold and platinum nano-particles. The anti-microbial nano- particles are fixed on the surface of the core nano-particles. The fixed anti- microbial metal nano-particles may be prepared by coating the core nano- particles with a metal salt or complex. In a following step the adsorbed metal ions or complexes have to be reduced to form a metal nano-particle with antimicrobial properties. The resulting particles are fixed on the surface of the core nano-particle and have a diameter in the range between 0,5nm and 10nm, preferred between 1nm and 5nm, in particular between 1nm and 2nm. In a preferred embodiment at least 70%, in particular at least 90% of the antimicrobial metal nano-particles fixed onto the surfaces of the core nano-particles fall into this diameter range.

The preferred diameter ratio of the core nano-particles to the anti-microbial metal nano-particles is between 1 : 4 and 1 : 100, in particular between 1 : 10 and 1 : 40.

The term "anti-microbial" covers in particular the anti-microbial function against eukaryotic microbes such as fungi and protists, and the anti-microbial function against prokaryotic microbes such as bacteria and prokaryotic algae and viruses.

The anti-microbial resin composition according to the present invention comprise polymers such as polyolefins, polyesters, polyvinylesters, poly(meth)acrylates, polyamides etc including homo- and co-polymers of the mentioned polymeric compounds. Preferred resin compositions comprise at least one polymer selected from the group consisting of polybutylene terephthalate (PBT)₁ polyethylene terephthalate (PET), acrylnitrile butadiene styrene (ABS), polycarbonate (PC), polystyrene (PS), polyester sulfone (PES), polyamides (PA, e.g. PA 612, PA610, PA66, PA6), polypropylene (PP), polyvinyl butyral (PVB) and polyethylene (PE).

A further aspect of the present invention is to provide a method for the preparation of the anti-microbial resin, wherein the distribution of the functional nano-particles in the resin is improved. The method comprising the steps of: (a) mixing the metal oxide and/ or ceramic core raw material with an organic solvent and an organic dispersing agent and

(b) breaking the metal oxide and/or ceramic core raw material into nano- particles e.g. by using equipment such as ball mill and dispersing the core nano-particles in the organic solvent preferably at the same time.

(c) dissolving the resin in an organic solvent preferably the same solvent used in step (a), e.g. by heating the mixture and

(d) preparing a solution of metal salts or metal complexes of anti-microbial metals, preferred in an organic solvent preferably in the same solvent used in step (a) and/or step (c) and

(e) mixing the solution of step (b) with the dispersion of the metal oxide core nano-particles and/or ceramic core nano-particles of step (d) and agitating the mixture that the surface of the metal oxides core nano-particles or ceramic core nano-particles is coated with the metal salt and/or complex and

(f) mixing the resin solution of step (c) with the resultant product of step (e)

(g) forming the anti-microbial metal nano-particles on the surface of the core nano-particles after mixing step (e) and prior, during or after mixing step (f),

(h) optionally removal of the solvents and, if appropriate, removal of the dispersing agent and resulting side products.

For dispersing the metal oxide and/or ceramic nano-particles in an organic solvent a dispersing agent, preferably an organic dispersing agent is used. Preferred dispersing agents are selected from the group of polymeric dispersing agents, like acrylic polymers or polyvinyl alcohols, or of silicates with at least one organic group (organic silicates), like tetraethyl orthosilicate. The organic dispersing agent is added preferably in an amount between 0.5% and 50% by weight, in particular between 5% and 20% by weight, with respect to the amount of metal oxide and/or ceramic compounds to be dispersed.

Preferred the metal oxide and/or ceramic compounds are mixed with the organic solvent in weight ratio between 1 : 5 and 5 : 1 , in particularly between 1 : 2 and 2: 1.

As organic solvent a solvent selected from the group of aliphatic or cyclic hydrocarbons which may be halogenated (e.g. hexane, toluene, chloroform or dichlormethane), ethers(e.g. diethyl ether, 1 ,4 dioxane), esters (e.g. ethyl acetate), ketones (e.g. Acetone), nitriles (e.g. Acetonitrile), and formamides (e.g. Dimethylformamide (DMF)) is preferred in particular a solvent of the group of petroleum such as N-methyl pyrolidone (NMP), meta cresol, dimethyl sulfoxide (DMSO), 1 ,1 ,2,2- tetrachloroethane or N-methyl formamide (NMF) is preferred. It is advantageous in view of the described method to use the same organic solvent in steps (a) to (d), in particular at least in steps (a) and (c).

In particular the use of N-methyl pyrolidone (NMP) or meta cresol is preferred as organic solvent, when the resin is selected from the group consisting of PBT, PET, ABS, PC, PS, PVB and PES. Dimethyl sulfoxide (DMSO), 1 ,1 ,2,2- tetrachloroethane, or N-methyl formamide (NMF) is used preferred as organic solvent when the resin is selected from the group consisting of PA, PP, PVB and PE.

Advantageously metal salts or complexes are used in step (d) which can be easily dissolved preferably in an organic solvent like NMP, meta cresol, DMSO or NMF. Preferred is the use of silver, gold or platinum salts, in particular their nitrates or halogenides, e.g. chlorides, fluorides or bromides or the use of silver, gold or platinum complexes with e.g. ammonia, thiosulfate, cyanide or thiocyanide ligands (examples are [Ag(NH₃)₂]⁺, [Ag(S₂O₃^]^3- or [Ag(CN)₂]^"). In addition platinum carbonyl, π-allyl, alkene or alkine complexes are suitable. Particularly preferred is the use of silver nitrate (AgNO₃) or platinum chloride (PtCI₃). However, in the case that the metal salt or complex can not be sufficient dissolved in the organic solvent a further dissolving agents can be applied. As dissolving agents are in particular acids or bases preferred. E.g. to prepare a metal salt solution of gold or platinum a treatment with aqua regia is possible. Subsequently the treated gold or platinum solution can be diluted in an organic solvent and used according to the above described method.

Preferred the metal salt to be reduced to the anti-microbial metal nano-particles are mixed with the organic solvent in a weight ratio of at least 1 : 1 , in particularly between 1 : 2 and 1 : 5. For dissolving the metal salt or complex in an organic solvent the mixture of the metal salt or complex and the organic solvent can be heated in particular between 40⁰C and 80⁰C.

The weight ratio of the used anti-microbial metal nano-particles to the core nano-particles is between 0,000001 : 1 and 0,1 : 1 , preferred between 0,00001 : 1 and 0,01 : 1 , in particular between 0,0001 : 1 and 0,001 : 1. So e.g. if silver nitrate is used as metal salt and zirconium dioxide is used as ceramic core nano-particle preferred 0,0157g - 0,157g AgNO₃ is solved with respect to 100g zirconium dioxide; if e.g. PtCI₃ is used as metal salt, then preferred 0,0155g - 0,155g of the salt is used with respect to 100g zirconium dioxide.

Subsequently the solution of the anti-microbial metal salt or complex is added to the dispersion of the metal oxide and/or ceramic core nano-particles. The mixture can be agitated so that the metal salt is adsorbed on the surface of the core nano-particles.

In a further step the adsorbed metal ions or complexes are reduced to form the metal nano-particles. The reducing step is carried out on the surface of the core nano-particle after the coating step (e) and before, during or after mixing the resulting particles with the dissolved resin (step (f)). The reducing step can be carried out simply by heating the mixture which comprises the metal salt or metal complex coated core nano-particles. In an alternative embodiment a reducing agent can be used instead or in addition. As reducing agent e.g. sodium borhydride (NaBH₄), lithium aluminum hydride, sodium sulfite, sodium dithionite or sodium thiosulfate may be used. Preferred the metal ions or complexes are reduced when the resulting solution of step (c) and the dispersion of step (e) is mixed by heating the mixture to a temperature above 60 ⁰C without additional reducing agents, in particular at a temperature between 100 ⁰C and 250 ⁰C, preferably between 140 ⁰C and 170 ⁰C. By reducing the adsorbed metal ions or complexes on the surface of the core nano-particles, fixed anti-bacterial metal nano-particles can be obtained with diameters between 0,5nm and 10nm. Advantageously fixed anti-bacterial metal nano- particles having a very low diameter size mainly between 1nm and 2nm can be reached, if prepared with the described method, in particular in the case that zirconium dioxide core nano-particles are used. The anti-microbial metal nano- particles are preferred attached on the surface of the core nano-particle physically (physisorption, via van der Waals forces). The metal nano-particles prepared with the described method are advantageously spherical, wherein "spherical" means that the ratio of the smallest to the greatest diameter of a metal nano-particle is greater than 0,7, preferably greater than 0,8.

The resin polymer can be dissolved in an organic solvent by heating the mixture of the polymer. Therefore advantageously organic solvents are used allowing the heating of the mixture until the polymeric resin is dissolved without vaporization of considerable amounts of the organic solvent. The preferred weight ratio of the polymeric resin and the used organic solvent is between 1 : 1 and 1 : 10, in particular between 1 : 3 and 1 : 7. E.g. in the case that PBT, PET or PA are used as resin material the preferred resin: solvent weight ratio is between 1 : 2 and 1 : 5, if one of the preferred organic solvents, NMF, DMSO₁ NMP or meta cresol, is used.

E.g. in the case that a polymer of the group acrylnitrile butadiene styrene (ABS), polycarbonate (PC), polystyrene (PS), polyester sulfone (PES), polypropylene (PP). polyvinyl butyral (PVB) and polyethylene (PE), in particular polybutylene terephthalate (PBT), polyethylene terephthalate (PET) and polyamide (PA), shall be solved in an organic solvent like NMP, meta cresol, DMSO or NMF the mixture can be heated up to 250⁰C, preferred between 100⁰C and 200⁰C, in particular preferred between 14O⁰C and 170⁰C which leads advantageously to a completely dissolved resin.

After mixing the resulting solutions of step (c) and step (e) the obtained mixture of step (f) and (g) can be treated in various methods to prepare alternative forms of an anti-microbial resin composition, e.g. a master batch. For example, the resulting mixture of step (f) and optionally after step (g) can be agitated with a polar solvent, like water, to remove polar side-products, in particular water soluble solvents, acids, like nitric acid or hydrochloric acid, and the dispersing agent. The water can be removed by using a tool such as centrifugal dehydrator. After removal of the water phase the anti-microbial resin composition can be dried in either a vacuum drying equipment or thermal drying equipment in a temperature range between 40 ⁰C and 100 ⁰C in order to attain powder form.

Another example is to form master batch chip with the resulting mixture of step (f) and optionally after step (g). That is by removing the solvents and dispersing agents in vacuum batch dryer by heating at a temperature range between 25O⁰C and 300⁰C and get a concentrate or master batch of anti-microbial resin composition. Then the resin composition can be cooled and cut into a grain form of master batch.

Another example is to mix the resulting mixture of step (f) and optionally after step (g) with resins in which the anti-microbial function is required and drying the composition to get a coated resin. In this way the resin surface shall be coated with the anti-microbial resin composition of this invention.

In a further embodiment an anti-microbial resin composition suitable for the direct preparation of final products can be produced with the described method of steps (a) to (g) if the resulting liquid resin composition shall be used or of steps (a) to (h) if a dried resin composition shall be used.

With the described method an anti-microbial resin composition concentrate with an amount of above 40% by weight of the functional particles or an anti- microbial resin composition master batch with an amount of between 1% and 50% by weight of functional particles or a finished anti-microbial resin composition with an amount between 0.1% and 5% by weight of the functional particles can be prepared directly. The concentrate may be used for the preparation of a master batch or finished anti-microbial composition by mixing the concentrate with a polymer. Analogously a finished anti-microbial resin composition can be prepared by mixing an anti-microbial resin composition master batch with a polymer. All polymers which can be mixed with the resin of the anti-microbial resin composition may be added to the anti-microbial resin composition concentrate or master batch. Preferred the same polymers are used which are suitable for the preparation of the anti-microbial resin composition, in particular selected from the group of polyolefins, polyesters, polyvinylesters, poly(meth)acrylates and polyamides, like polybutylene terephthalate (PBT), polyethylene terephthalate (PET), acrylnitrile butadiene styrene (ABS), polycarbonate (PC), polystyrene (PS), polyester sulfone (PES), PA 612, PA610, PA66, PA6, polypropylene (PP), polyvinyl butyral (PVB) and polyethylene (PE) including homo- and co-polymers of these compounds.

By the mechanical treatment process for the preparation of the core nano- particles, in particular the ceramic core nano-particles, in the presence of a dispersing agent and an organic solvent, an advantageous surface structure with almost regular distributed deepenings can be generated. Into the deepenings the anti-microbial metal nano-particles coated with polymer can be arranged in the following steps, in particular by the preferred thermal treatment (100°C-250°C). Because of the advantageous surface structure the antimicrobial nano-particles are almost regular distributed on the surface. Due to these improved distribution and fixation of the functional particles by the added resin the functional particles are not aggregated and kept unchanged in following production steps, e.g. during the preparation of a finished polymer composition with a master batch composition prepared with the described method. By the disclosed method the preparation of an anti-microbial resin composition is possible preventing oxidization or aggregation of the anti-microbial metal nano-particles by preparation of resin solution with an organic solvent rather than melting it at high melting temperatures and by the use of a dispersion of functional nano-particles, comprising suitable core nano-particles with antimicrobial metal nano-particles on its surface preferred in the same organic solvent. Due to the fact that small functional particles or core nano-particles coated with a metal salt or complex dispersed in an organic solvent with a diameter of size under 110nm are used which can be easily mixed with a dissolved resin an improved distribution of the particles in the resin is reached. The improved distribution can be also reached in an end-product or in an intermediate resin product (e.g. a resin powder) by using a concentrate or master batch of the claimed anti-microbial resin composition, because an agglomeration of the functional particles during further manufacturing steps is prevented by the presence of a polymeric compound in the claimed resin composition. In addition the amount of anti-microbial metal can be reduced between 5 to 150 times compared with the use of silver nano-particles which are not fixed on the surface of a carrier. The immense reduction of the metal amount necessary for sufficient anti-microbial function is caused by the very small diameter of fixed metal nano-particles and the improved distribution of the functional particles in the resin.

A further embodiment of the present invention is the use of functional particles comprising a metal oxide and/or ceramic nano-particle core with a diameter of 5nm to 100nm and anti-microbial metal nano-particles with a diameter of 0,5nm to 10nm, wherein the anti-microbial metal nano-particles are fixed onto the surface of the metal oxide and/or ceramic nano-particle core for the preparation of anti-microbial resin compositions.

The described anti-microbial resin compositions optionally comprise further additives e.g. anti-oxidizing agents, nucleating agents, lubricants, pigments etc. in a preferred amount of less than 30% by weight, in particular between 1% and 15% by weight, with respect to the weight of the anti-microbial resin composition BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a flow chart illustrating a method of manufacturing an anti-microbial PBT, PET or PA resin composition according to an exemplary embodiment of the invention. According to FIG. 1 , step 1 zirconia raw material is dissolved in an organic solvent and supplemented with an organic dispersing agent (e.g. TEOS). The mixture is dispersed while breaking the zirconia material into nano- particles with a size of 5nm to 100nm e.g. by a ball mill (step 2).

In addition a polymer, e.g. PBT, PET or PA is heated together with an organic solvent to melt and dissolve the polymer (step 3). In a further parallel step AgNO₃ is diluted in an organic solvent (step 4). The resulting silver salt solution is added to the dispersion resulting from step 2 and agitated that zirconia nano- particles are obtained coated with silver ions (step 5). In a further step the resulting product of step 5 is mixed with the polymer solution of step 3 and subsequently the silver ions are reduced to silver nano-particles. To purify the resulting resin composition water is added to the mixture to remove water soluble materials in particular the dispersing agent and side products of the reduction step (step 6). Subsequently the mixture is dried (step 7). The resulting resin composition comprise zirconia nano-particles having a surface coated with silver nano-particles with anti-microbial properties which are almost uniformly distributed in the resin.

FIG. 2a and 2b shows schematically the formation of the metal nano-particles on the surface of zirconia core nano-particles. Fig. 2a shows a zircona core nano-particle coated with AgNO₃ salt, prepared e.g. in accordance with step (e) of the described method. Fig. 2b shows the zirconia core nano-particle after mixing the dispersed zirconia particles of Fig. 2a with the solved resin and heating of the mixture to reduce the silver ions on the surface of the zirconia particles to silver nano-particles. Fig. 2c shows an enlarged scheme of the surface of the zirconia particle of Fig. 2b with physicochemically fixed silver nano-particles. DETAILED DESCRIPTION OF THE INVENTION

Although the present invention is described with reference to the following certain exemplary embodiments it will be understood by those skilled in the art that a variety of modifications and variations may be made to the present invention without departing from the spirit and scope of the present invention as defined in the appended claims and their equivalents.

Example 1 : The first exemplary embodiment is a method of manufacturing an anti-microbial polybutylene terephthalate (PBT) composition.

In a first step, 7Og of zirconia powder which comprise aggregated particles with a size of 0.1 micrometer to 500 micrometer is put into a 7Og of NMP. Then, 21 g of tetraethyl orthosilicate (TEOS) serving as a dispersing agent is added. Then, the prepared zirconia mixture is broken into nano size particles and dispersed by using a ball mill, so that the zirconia nano-particles with a size of 5nm to 100nm are prepared. The zirconia solution is milled at 200rpm for 48 hours. 90Og of zirconia balls of which the diameter is 1mm to 3mm are used. Then the zirconia nano-particles in the solution is further homogenized.

In the next step 3Og of PBT is added to 12Og of NMP. After the PBT is added to the solvent the mixture is heated to the temperature of 140 ⁰C such that the PBT is completely dissolved in the solvent.

In a further step, 0.055g of AgNO₃ is dissolved in the 0.55g of NMP. AgNO₃ is used to obtain silver nano-particles. AgNO₃ includes 63.5wt% silver ions. The amount of the solvent into which AgNOβ is dissolved does not have an effect upon reaction, but the weight of the solvent should be preferably not smaller than that of AgNOβ. The solvent is heated at a temperature of 60⁰C so as to prepare a silver ion solution. In a further step the zirconia nano-particle solution and the silver ion solution are mixed and agitated. By the agitation, the dispersed zirconia nano-particles are coated with silver ions. Subsequently the resultant product and the PBT solution are mixed at a temperature of approx. 140 ⁰C. During this process the silver ions coated on the zirconia surface are reduced to silver nano-particles mostly with a size of 1 nm to 2nm by reduction.

Then, 1000g of water is added to the mixture, and the mixture is agitated to remove water-soluble materials. The water-soluble materials are in particular the solvent, nitric acid or hydrochloric acid, and the dispersing agent. The water, the solvent, the nitric acid, the hydrochloric acid, and the dispersing agent are all removed through dehydration in a centrifugal dehydrator so a PBT antimicrobial synthetic-resin composition is obtained in which the zirconia nano- particles having a surfaces coated with silver nano-particles are almost uniformly distributed in the resin.

The PBT resin compositions in which the zirconia nano-particles having a surfaces coated with silver nano-particles are nearly homogenous distributed exhibit an excellent anti-microbial characteristic and additionally a far-infrared radiation characteristic through the silver nano-particles and the zirconia nano- particles, regardless of the position thereof.

Further, when textiles such as fibers or filaments are manufactured using the PBT resin materials, the textiles such as fibers or filaments can exhibit an nearly homogenous anti-microbial characteristic and far-infrared radiation characteristic across the entire area thereof. Furthermore, the zirconia nano- particles with a size of 5nm to 100nm almost uniformly dispersed without being conglomerated. Therefore, when textiles such as fibers or filaments are manufactured, the textiles have no increased risk of being broken during the manufacturing process.

Example 2: The second exemplary embodiment is a method of manufacturing an anti-microbial polyethylene terephthalate (PET) composition. In a first step 7Og of zirconia powder is mixed into 7Og of NMP. Then, 21 g of TEOS serving as a dispersing agent is added to the solvent, in which the zirconia powder is mixed, so that the zirconia powder is almost uniformly dispersed in the solvent. In a next step, the prepared zirconia mixture is further dispersed while being broken into nano size particles by using a ball mill. The zirconia solution is milled at 200rpm for 48 hours using 90Og of zirconia ball of which diameter is 1mm to 3mm. The zirconia powder is thereby cut into zirconia nano-particles with a diameter of 5nm to 100nm, and the dispersion degree of the zirconia nano-particles within the dispersion solution is further homogenized.

In a further step 3Og of PET is added to 12Og of NMP, and the mixture is dissolved by heating at a temperature of 140 ⁰C.

In addition 0.055g of AgNO₃ is dissolved in 0.55g of NMP and heated at a temperature of 60 ⁰C so as to prepare a silver ion solution.

In the next step, the zirconia nano-particle solution resulting from the previous step and the silver ion solution are mixed and agitated. By the agitation, the dispersed zirconia nano-particles are coated with silver ions. "Coating" means that the silver ions are physically attached on the surface of the zircoina nano- particles with a diameter of 5nm to 100nm.

Further, the resultant product of the above step and the PET solution are mixed at a temperature of 140 ⁰C. During this process metal ions coated on the zirconia surface are reduced to silver nano-particles mostly with a size of 1 nm to 2nm by reduction.

After mixing the resulting functional particle dispersion with the PET solution is completed, 1000 g of water is added to the mixture, and the mixture is agitated to remove water-soluble materials. The water, the solvent, the nitric acid, and the dispersing agent are removed by drying steps in a centrifugal dehydrator, thereby obtaining an anti-microbial PET resin composition in which the zirconia nano-particles having surfaces coated with silver nano-particles are almost uniformly distributed.

The silver nano-particles of the first and second example can be substituted with platinum or gold nano-particles. To apply the platinum or gold nano- particles, a solution in which 0.1g of platinum or gold is melted 0.5g of aqua regia and dissolved into 5.4g of a solvent, and the solution is added to the zirconia nano-particle solution and then agitated with the core nano-particle dispersion. Then, it is possible to obtain an anti-microbial PET resin composition in which the zirconia nano-particles having surfaces coated with platinum or gold nano-particles with a diameter of 0,5nm to 10nm which are uniformly distributed.

In the first and second exemplary embodiments, the method of manufacturing PBT and PET materials can be in particular applied to manufacture also acrylonitrile dutadiene styrene (ABS), polycarbonate (PC), polystyrene (PS)₁ polyvinyl butyrul (PVB) and polyester sulfone (PES) resin compositions.

Example 3: The third exemplary embodiment is a method of manufacturing an anti-microbial polyamide resin composition, wherein the polyamides was chosen from e.g. PA612, PA610, PA66, PA6.

In a first step, 7Og of zirconia powder is mixed into 7Og of dimethyl sulfoxide (DMSO). Then, 21g of TEOS serving as dispersing agent is added to the solvent, in which the zirconia powder is mixed, such that the zirconia powder is uniformly dispersed in the solvent. In the next step the prepared zirconia mixture is dispersed and broken into nano-particles by using a ball mill. The ball mill is operated with 200rpm for 48 hours by using 90Og of zirconia balls of which the diameter is 1mm to 3mm. The zirconia powder is cut into zirconia nano-particles with a diameter of 5nm to 100nm, and the dispersion degree of the zirconia nano-particles within the dispersion solution is further homogenized. In a further step 3Og of polyamide is added to 12Og of DMSO, and the mixture is heated at a temperature of 140⁰C until the polyamide is dissolved.

In addition 0.055g of AgNO₃ are dissolved in 0.55g of the same solvent (DMSO) as that used above, and the mixture is heated at a temperature of 60⁰C to prepare a silver ion solution. Subsequently, the zirconia nano-particle solution as the resultant product of the previous step and the silver ion solution are mixed and agitated. By the agitation, the dispersed zirconia nano-particles are coated with silver ions. Then, the resultant product and the polyamide solution are mixed at a temperature of 140 ⁰C. During this process metal ions coated on zirconia surface became nano-particles mostly with a size of 1nm to 2nm by reduction.

Then, 100Og of water is added to the mixture, and the mixture is agitated to remove water-soluble materials. The water, the solvent, the nitric arid, and the dispersing agent are removed by drying the resin composition in a centrifugal dehydrator, thereby obtaining a polyamide composition in which the zirconia nano-particles having a surface coated with silver nano-particles are almost uniformly distributed.

The silver nano-particles can be substituted with platinum or gold nano- particles.

In the third exemplary embodiment, the method of manufacturing the PA resin compositions can be preferred applied to manufacturing polypropylene (PP), polyvinyl butyral (PVB) and polyethylene (PE) resin compositions using the same method.

The concentrates of the anti-microbial resin composition produced in accordance to the first, second and third example comprising approx. 70% by weight of zirconia core nano-particles coated with anti-microbial silver metal nano-particles. The concentrates are subsequently extruded together with additional polymer wherein the amount of concentrate was 20% by weight in respect to the added polymer. Then a mono filament was produced by mixing 4% by weight of the master batch in respect of the polymer further added to the composition.

The resulting anti-microbial resin compositions manufactured in such a manner exhibit more than 90.0%, in particular more than 99.9% monovalency with respect to Staphylococcus aureus ATCC 6538 and Klebsiella pneumoniae ATCC 4352 in an antimicrobial test (TEST METHOD; ASTM 2149E).

In a far-infrared radiation test performed at a temperature of 40⁰C, the radiation rate and radiation energy of the resin compositions have been measured as 0.920 and 371 W/m2, respectively. All the samples have exhibited identical monovalency and far-infrared radiation characteristics.

According to the present invention, an anti-microbial resin composition is manufactured, wherein the zirconia nano-particles coated with silver or platinum nano-particles are almost uniformly distributed in the resin. Therefore, resin products such as fibers and filaments manufactured using the resin compositions can exhibit improved, nearly uniform functionality across the whole product, and manufacturing problems caused by functional nano-particles aggregation are prevented.

The described anti-microbial resin compositions respectively the method for preparing the same could be used in the following applications:

Masterbatch production or compounding:

The anti-microbial resin compositions produced according to the invention could be used for various anti-microbial plastic masterbatch productions. In such a case, a master batch of an anti-microbial synthetic-resin compositions produced by this invention should be added to and dispersed in plastics evenly. The mixing ratio could be widely varied dependent on the application. In compounding industry, the anti-microbial resin composition could be added to a plastic extruding process directly. The mixing ratio could be also widely varied dependent on the application.

Plastic industry:

Anti-microbial resin compositions produced according to this invention could be applied to the various plastic forms such as resin, film, sheet, filament, fiber, non-woven, injection molding etc. Corresponding methods are the use of master batch technology e.g. as described above or compounding in an extrusion process.

Finished products:

Various product types described in the previous paragraph could be used in various industries where anti-microbial function is needed such as food, medical, cosmetic, textile, building, packaging industries. Final products in those industries could be for example tooth brushes, clothes, food and medical packaging, paints, toys, cosmetic brushes, building interiors, non woven sanitary products etc.

Claims

PATENT CLAIMS

1. An anti-microbial resin composition comprising functional particles in an amount of 0,1% to 99% by weight of the solid compounds of the anti- microbial resin composition, wherein the functional particles comprising a metal oxide nano-particle core and/or ceramic nano-particle core with a diameter of 5nm to 100nm and anti-microbial metal nano-particles with a diameter of 0,5nm to 10nm, wherein the anti-microbial metal nano- particles are fixed onto the surface of the metal oxide and/or ceramic nano-particle core.

2. The anti-microbial resin composition according to claim 1 , wherein the anti-microbial metal nano-particles comprise particles selected from the group consisting of silver, platinum and gold.

3. The anti-microbial resin composition according to claim 1 , wherein the resin comprises a polymer selected from the group consisting of polybutylene terephthalate (PBT), polyethylene terephthalate (PET), acrylnitrile butadiene styrene (ABS), polycarbonate (PC), polystyrene (PS), polyester sulfone (PES), polyamide (PA), polypropylene (PP), polyvinyl butyral (PVB) and polyethylene (PE).

4. A method of manufacturing an anti-microbial resin composition according to any one of claim 1 to 3 comprising the steps of

(a) mixing the metal oxide and/ or ceramic core raw material with an organic solvent and an organic dispersing agent and

(b) breaking the metal oxide and/or ceramic core raw material into nano- particles and dispersing the core nano-particles in the organic solvent.

(c) solving the resin in an organic solvent and (d) preparing a solution of metal salts or metal complexes of antimicrobial metals by using an organic solvent and

(e) mixing the solution of step (d) with the dispersion of the metal oxide core nano-particles and/or ceramic core nano-particles of step (b) that the surface of the metal oxides core nano-particles or ceramic core nano- particles is coated with the metal salt or metal complex and

(f) mixing the resin solution of step (c) with the resultant mixture of step (e) and

(h) optionally removal of the solvents.

5. The method according to claim 4, wherein N-methyl pyrolidone (NMP) or meta cresol is used as organic solvent when the resin is selected from the group consisting of PBT, PET, ABS₁ PC, PS, PVB and PES.

6. The method according to claim 4, wherein dimethyl sulfoxide (DMSO) or N-methyl formamide (NMF) or 1 ,1 ,2,2-tetrachloroethane is used as organic solvent when the resin is selected from the group consisting of PA, PP, PVB and PE.

7. The method according to any one of claims 4 to 6, wherein the metal salt in step (d) is AgNO₃ solution or PtC^.

8. The method according to any one of claims 4 to 6, wherein the metal salt is a gold or platinum salt dissolved in aqua regia supplemented with the same organic solvent as used in step (a).

9. The method according to any one of claims 4 to 8, wherein the dispersing agent in step (a) is an acrylic polymer or an organic silicate.

10. The method according to any one of claims 4 to 9, wherein the anti- microbial metal nano-particles are formed on the surface of the core nano-particles by reducing the metal salt or metal complex by heating the resin composition during or after mixing step (f).

11. Use of functional particles comprising a metal oxide nano-particle core and/or ceramic nano-particle core with a diameter of 5nm to 10Onm and anti-microbial metal nano-particles with a diameter of 0,5nm to 10nm, wherein the anti-microbial metal nano-particles are fixed onto the surface of the metal oxide nano-particle core and/or ceramic nano-particle core for the preparation of anti-microbial resin compositions.