Antimicrobial polymer composition

FIELD OF THE INVENTION
The present invention relates to an antimicrobial polymer composition.
BACKGROUND OF THE INVENTION
An antimicrobial polymer composition comprising a polymer and an antimicrobial composition having an antimicrobial coat of an aluminosilicate on the surface of silica gel, wherein said aluminosilicate containing antimicrobial metal ions, such as silver, copper and zinc, is disclosed in the U.S. Pat. Nos. 5,244,667 and 5,298,252.
Since said antimicrobial composition is effective against common fungi and also exhibits excellent biocidal activity against mildew, research and development leading to new applications have been carried out. Furthermore, research and development of an antimicrobial polymer composition comprising said antimicrobial composition is also carried out and some uses have been developed.
However, if said silica gel based antimicrobial composition is added to a polymer and molded under heating, it is known that an undesirable discoloration or coloring occurs in some polymers under certain processing conditions, due to an interaction of antimicrobial composition with polymer or an interaction of antimicrobial composition with additives or catalyst contained in a polymer.
Furthermore, an antimicrobial polymer molding may discolor or degrade with time and an economical value may be damaged. In some polymers, a discoloration is accelerated by a radiation of sunlight or ultraviolet light.
Many researches have been carried out to resolve the defects of the prior antimicrobial polymer composition containing the above mentioned antimicrobial composition. A discoloration resistance and a weatherability are improved, however, they are not satisfactory, yet. The technology that can prevent a coloration which occurs during blending or molding under heating or a variety of the molded article with time has not been developed.
Accordingly, it is desired to develop a novel technology that can prevent a discoloration or coloration of the antimicrobial polymer composition and improve the weatherability. The main object of the present invention is to provide a novel antimicrobial polymer composition which resolves the above mentioned defects of the prior art.
SUMMARY OF THE INVENTION
The present invention relates to an antimicrobial polymer composition comprising a thermosetting polymer and an antimicrobial composition having an antimicrobial coat of an aluminosilicate on the surface of silica gel wherein said aluminosilicate containing antimicrobial metal ions, characterized in that said antimicrobial polymer composition further comprises thiabendazole. Furthermore, the present invention relates to said antimicrobial polymer composition further comprising inorganic additives.
The antimicrobial polymer composition of the present invention has an excellent biocidal ability, a discoloration resistance and a weatherability and shows less variation with time.
DETAIL DESCRIPTION OF THE INVENTION
The present inventor has found that a selection of an additive is important to improve a heat resistance, a weatherability and a light-resistance and minimize a discoloration of the antimicrobial polymer composition comprising a thermosetting polymer and silica gel based antimicrobial composition.
As the result of research of additives, the inventor has found that thiabendazole (hereinafter referred as TBZ) improves a heat resistance, a weatherability and minimizes a discoloration of the antimicrobial polymer composition comprising a thermosetting olymer and an antimicrobial composition having an anti-microbial coat of an aluminosilicate on the surface of silica gel, wherein said aluminosilicate containing antimicrobial metal ions. In the present specification, an antimicrobial composition coat of an aluminosilicate on the surface of silica gel, wherein said aluminosilicate containing antimicrobial metal ions is occasionally referred to as silica gel based antimicrobial composition. Furthermore, an addition of the after mentioned inorganic additives further improves physical properties of the obtained antimicrobial polymer composition.
The present invention provides a novel antimicrobial polymer composition comprising a thermosetting polymer and an antimicrobial composition having an antimicrobial coat of an aluminosilicate on the surface of silica gel, wherein said aluminosilicate containing antimicrobial metal ions, characterized in that said antimicrobial polymer composition further comprises thiabendazole.
The silica gel to be used as the starting material may be in the form of a powder granules, beads or any other shaped parts. However, considering the case of performing a chemical treatment on silica gel with an alkali solution and an aluminate solution, silica gel in a fine form is preferred. A more preferred type is porous silica gel in which a great number of capillary pores are present to provide large pore sizes and specific surface areas. For example, silica gel that is preferably used as the staring material has a pore volume of at least 0.3 cm.sup.3 /g, and one having a void volume of at least 0.4 cm.sup.3 /g is more preferred. The pore size of silica gel is preferably as large as possible, for example, at least of 50 .ANG., more preferably at least 70 .ANG.. The specific surface area of silica gel is at least 100 m.sup.2 /g, more preferably at least 200 m.sup.2 /g.
The silica gel material having these characteristics is preferred for the following reasons. First, silica gel having the physical data listed above is very porous and the capillary pores in it have a very active surface. If such silica gel is chemically treated and aluminosilicate coat is formed on the active surface s of capillary pores, and if microbial metals are retained on that coat in a stable way by ion-exchange, chemical species and metal ions that take part in reaction will diffuse rapidly enough to permit the intended chemical reaction to proceed smoothly on the surfaces of pores in the silica gel. Further, the microbicidal metal in the antimicrobial composition of the present invention is distributed substantially uniformly on the surface of pores in silica gel in a preferred way, so microbial metal ions formed as a result of dissociation will diffuse rapidly through pores to insure that those microbial metal ions contact bacteria or fungi over a sufficiently large area to inhibit their growth or kill them effectively.
The aluminosilicate coat formed on the surface of the silica gel matrix is generally represented by the following general formula:
XM.sub.2/n O.Al.sub.2 O.sub.3.ySiO.sub.2.zH.sub.2 O
where x and y represent the numbers of molecules of the metal oxide and silicon dioxide, respectively: M is an ion-exchangeable metal: n is the atomic valence of M; and z is the number of molecules of water. M is usually a monovalent metal such as Li, Na or K and may sometimes be NH.sub.4.sup.+. If desired, such monovalent metals or NH.sub.4.sup.+ may be substituted either partially or totally with a divalent metal such as Mg, Ca, Sr, Ba, Mn, Ni, Co or Fe.
Microbial metal ions are introduced by an ion-exchanging reaction with M of the above formula. Microbicidal metal ions may be any metal ions that effectively exhibit an antimicrobial and/or microbicidal action and such microbicidal metal ions are not limited to any particular kinds. Typical examples of microbicidal metal are silver, copper, zinc, mercury, tin, lead, bismuth, cadmium, and these metals may be used either on their own or as admixture.
Preferably, the antimicrobial metal ions are silver ions or silver ions and one or two metal ions selected from the group consisting of zinc ions and copper ions. A content of the antimicrobial composition is preferably at least 0.2% by weight of the antimicrobial polymer composition to provide satisfactory antimicrobial effects. A content of the silver ions is preferably at least 0.3% by weight of the antimicrobial composition to provide a good antimicrobial rate. A content of TBZ is preferably at least 0.03% by weight of the antimicrobial polymer composition to provide good weatherability and discoloration resistance.
An antimicrobial polymer composition of the present invention may further comprise at least one additive selected from the group consisting of titanium dioxide, zirconium oxide, cerium oxide and layer silicates. Such as antimicrobial polymer composition provides a remarkably improved weatherability and discoloration resistance. A natural resin, a semi-synthetic resin and a regenerated resin can be used as a polymer of the antimicrobial polymer composition of the present invention.
To prepare the antimicrobial polymer composition of the present invention, an amorphous antimicrobial composition having an antimicrobial coat of an aluminosilicate on the surface of micro pores and/or macro pores of silica gel wherein said aluminosilicate contains silver ions and one or two optional metal ions selected from the group consisting of zinc and copper is preferably used as an antimicrobial composition. Said antimicrobial composition may contain non-biocidal metal ions having valences of 1 to 3 or ammonium ions.
The process for preparing the amorphous antimicrobial composition is well known as disclosed in U.S. Pat. No. 5,244,667 and briefly stated below.
The process comprises a first step of chemically treating a porous silica gel with an alkali solution and an aluminate solution and then forming an antimicrobial coat on the thus-treated surface of the silica gel and the second step of treating with a salt solution comprising at least one type of antimicrobial metal ion to allow antimicrobial metal ions �preferably, Ag.sup.+ and optional Zn.sup.2+ and/or Cu.sup.2+ ! to be retained in the aluminosilicate coat so that an antimicrobial coat is formed. In the first step, aluminic acid ions �Al(OH).sub.4 ;AlO.sub.2 .multidot.2H.sub.2 O! react with Si(OH).sub.4 �SiO.sub.2 .multidot.2H.sub.2 O as a monomer! present on a surface of pores (micro pores and/or macro pores) in the silica gel to form negatively charged aluminosilicate ions.
A firm ionic bond is formed between aluminosilicate ions and porous silica gel so that the release of the former from the later gel body is completely prevented. In the second step, an ion-exchange treatment is carried out in order to retain antimicrobial and/or microbicidal ion, preferably Ag.sup.+ and optional Zn.sup.2+ and Cu.sup.2+ ions, in the thin aluminosilicate layer. By performing above process, antimicrobial metal ions are exchanged with ion-exchangeable metal ions in the aluminosilicate layer and thus formed antimicrobial layer is fixed strongly on the surface of the silica gel pores. Through the above procedure, the antimicrobial composition used in the present invention is prepared.
A predetermined amount of necessary antimicrobial metal ions in the antimicrobial composition is able to present in the form of single metal ion or composite metal ions, for example, Ag.sup.+, Ag.sup.+ --Zn.sup.2+, Ag.sup.+ --Cu.sup.2+, and Ag.sup.+ --Zn.sup.2+ --Cu.sup.2+. In addition to the above metal ions, the antimicrobial composition may contain non-biocidal metal ion having valences of 1 to 3, such as monovalent alkali metal ions, nickel and other alkaline earth metal ions with divalent, trivalent rare earth elements �lanthanoid elements: Ln.sup.3+, elements having an atomic number of from 58 to 71, 21 (Sc), 39(Y) and 57(La)! and zirconium (in a form of zirconyl:ZrO.sup.2+). Furthermore, the antimicrobial composition may contain ammonium ions, such as NH.sub.4.sup.+, C.sub.7 H.sub.15 N.sub.2.sup.+, C.sub.3 H.sub.16 N.sup.+, Me.sub.4 N.sup.+ (TMA:tetramethylammonium ion), Et.sub.4 N.sup.+ (TEA: tetraethylammonium ion), and Pr.sub.4 N.sup.+ ((TPA:tetrapropylammonium ion).
The antimicrobial composition used in the present invention is prepared by the above-mentioned process and comprises a silica as a major component thereof. It comprises preferably at least 70 wt % of SiO.sub.2 and 15 wt % or less of alumina (Al.sub.2 O.sub.3). It further comprises antimicrobial metal ions, such as Ag, Zn and Cu, and non-biocidal metal ions having a valence of 1 to 3. Such an antimicrobial composition has a large SSA, typically 350-600 m.sup.2 /g, leading to high porous. A form of the antimicrobial composition is not restricted and it is preferably used as a fine powder or a ground particle.
The antimicrobial composition used in the present invention exhibits an excellent antimicrobial effect against fungi and good mildeweidal effects.
TBZ is used to prevent a discoloration of the antimicrobial polymer composition and to improve a weatherability. The chemical formula of TBZ is 2-(4-thiazoyl)-benzimidazole, C.sub.10 H.sub.7 N.sub.3 S, and available from MELK Co. Ltd. TBZ is a pale yellow powder and has a molecular weight of 201.25, a melting point of 300.degree. C., a specific gravity of 1.44 and a decomposition temperature of 700.degree. C. TBZ has an imprimatur as a food additive from FDA (Food & Drug Administration in the U.S). TBZ has LD50s of 3600 mg/kg(mouse) and 3800 mg/kg(rabbit) and has a large safety to an organism. TBZ is used as a mildewcide, however it is known that TBZ has no biocidal ability.
It is unknown that TBZ prevents a discoloration, a coloration with time of antimicrobial polymer composition comprising silica gel based antimicrobial composition, and improve a weatherability of the antimicrobial polymer composition. The inventor investigated many kinds of weatherability modifiers, compounding ingredients, antioxidants, brighteners and pigments and found that Although, TBZ is an organic compound containing sulfur, there is no tendency to inhibit an antimicrobial ability of the silica gel based antimicrobial composition comprising silver ions.
Regarding to many kinds of polymers, a discoloration and variation with time of the compositions can be prevented by an addition of TBZ at the level from 0.03 to 3% by weight of the polymer. Furthermore, an antimicrobial ability of the polymer composition against fungi is not changed by the addition of TBZ. Accordingly the obtained antimicrobial polymer composition represents excellent antimicrobial ability.
The present invention further provide an antimicrobial polymer composition comprising thermosetting polymer, at least 0.2 wt % of before mentioned antimicrobial composition, at least 0.03 wt % of TBZ and at least one additive selected from the group consisting of titanium dioxide(TiO.sub.2), zirconium oxide(ZrO.sub.2), cerium oxide(CeO.sub.2) and layer silicate. A discoloration of the composition and a weatherability are improved significantly by an opacifying property thereof. The layer silicate includes talc; Mg.sub.3 (Si.sub.4 O.sub.10)(OH).sub.2, mica such as Muscovite: Kal.sub.2 (AlSi.sub.3 O.sub.10 (OH).sub.2, phlogopite: KMg.sub.3 (AlSi.sub.3 O.sub.10)(OH).sub.2, Lepidolite: K(Li.sub.2,Al)(Si.sub.4 O.sub.10)(F,OH).sub.2, Margarite: CaAl.sub.2 (Al.sub.2 Si.sub.2 O.sub.10)(OH).sub.2, and Vermiculite ((CaMg).sub.x/2 (Mg,Fe,Al).sub.3 (Al,Si).sub.4 O.sub.10 (OH).sub.2 .multidot.mH.sub.2 O; smectite such as Monmorillonite: Na.sub.x (Al.sub.2-X)Mg.sub.x (Si.sub.4 O.sub.10)(OH).sub.2 .multidot.mH.sub.2 O, Saponite: Ca.sub.x/2 Mg.sub.3 (AlxSi.sub.4-x O.sub.10)(OH).sub.2 .multidot.mH.sub.2 O, and Sauconite: M.sub.x (Zn,Mg).sub.3 (Al.sub.x Si.sub.4 XO.sub.10)(OH).sub.2 .multidot.mH.sub.2 O.
An explanation as to the polymer used in the present invention is provided in the following.
Both halogenated and non-halogenated organic thermosetting polymers may be used in preparing the antimicrobial polymer composition of the present invention. Non-halogenated organic polymers used in the present invention are not limited to any particular kinds and may be synthetic or semi-synthetic and include the following: thermosetting synthetic polymers such as phenolic resins, urea resins, melamine resins, unsaturated polyester resins, epoxy resins and urethane resins. If a strong antimicrobial and/or microbicidal effect is necessary, SSA of the polymer composition is preferably increased and is preferably foamed or otherwise shaped into a net, a fiber, etc. Halogenated organic polymers that can be used in the present invention also are not limited to any particular kinds.
The time at which the silica gel based antimicrobial composition is added to the polymer and the method by which it is added are not limited in any particular way in the present invention. For example, the antimicrobial composition may be mixed with a starting monomer and the mixture is then polymerized. In another method, the composition may be mixed with a reaction intermediate and the mixture is then polymerized. Alternatively, the composition may be mixed with the complete polymer, if desired, the silica gel based antimicrobial composition is mixed with polymer pellets or a master batch is prepared from a polymer composition containing the antimicrobial composition and the mixture or master batch is shaped to a desire form. In still another method, the antimicrobial composition is mixed with a molding dope, for example, a spinning solution. The procedure of these methods is hereinafter referred to simple as "mixing the silica gel based antimicrobial composition with a polymer or adding it to the polymer".
A suitable method may be adopted taking into account the characteristics of the polymer used and process conditions. In ordinary cases, the silica gel based antimicrobial composition is desirably mixed with the polymer just before molding. However, in order to insure more efficient dispersion of the silica gel based antimicrobial composition, it may be mixed with a monomer. When a predetermined amount of the antimicrobial composition is to be added to a polymer, the atmosphere (e.g. an oxidizing atmosphere such as the air or an inert gas atmosphere such as N.sub.2 or CO.sub.2), the temperature for mixing or the mixing time may be held at preferred conditions in accordance with the specific characteristics of the polymer used. The silica gel based antimicrobial composition is preferably used in an amount of 0.2-20 wt % of the total weight of the polymer composition. If the content of the silica gel based antimicrobial composition is less than 0.2 wt % of the total weight of the polymer composition, the antimicrobial and/or microbicidal activity of the polymer composition is often unsatisfactory against common bacteria and fungi. If the content of the silica gel based antimicrobial composition is more than 20 wt % of the total weight of the polymer composition, the antimicrobial and/or microbicidal activity of the resulting polymer composition is saturated and any further addition of the silica gel based antimicrobial composition will not contribute to an improved antimicrobial and/or microbicidal action. Furthermore, an excessive addition of the silica gel based antimicrobial composition has the potential to deteriorate the physical properties of the obtained polymer composition.
The particle size of the silica gel based antimicrobial composition that is advantageously used to produce the antimicrobial polymer composition of the present investigation is discussed below.
While there is no particular limitation on the particle size of the silica gel based antimicrobial composition, there is of course a preferred range depending on the specific use of the product. For example, particles of the antimicrobial composition with sizes of 548-149 micro meters (30-100 mesh) can be used for mixing with the polymer but in order to insure more uniform dispersion in the polymer, smaller particles, for example, those having sizes of 200-300 mesh or much finer particles with sizes of from several micro meters to less than a hundred micro meters, may be used.
The particle size of the antimicrobial composition may be adjusted by selecting a preferable mill, such as JET mill depending on a purpose of the product. When the antimicrobial polymer composition of the present invention is a shaped part having a certain thickness, for example, in the case where it is to be applied to various types of containers, pipes, granules of filaments of large denier, the silica gel based antimicrobial composition may have particle sizes of larger than several tens or several hundreds micro meters. If, on the other hand, the polymer composition is tube shaped into fibers of fine denier or thin films, the particle size of the silica gel based antimicrobial composition is desirably small For example, in the case of manufacturing fibers for apparel particle sizes of not more than 5 micro meters are preferred.
In addition to the silica gel based antimicrobial composition, the antimicrobial polymer composition of the present invention may contain other ingredients that are commonly used in the art. Examples of such secondary ingredients include: polymerization catalysts, stabilizers, weathering (lightfast) agents, compounding agents, antioxidants, activators, matting agents, foaming agents, flame retardants, modifiers, brighteners, pigments (colorants), inorganic or organic fillers, various plasticizers and lubricants. These additives may be incorporated as required. The antimicrobial polymer composition of the present invention may also contain liquids or organic solvents. When said composition is to be used as a shaped part, its shape and size are in no way limited. In order to provide the shaped part with an antimicrobial and/or microbicidal activity, it may be imparted to the whole part of the polymer, or if desired, to only part thereof When the microbicidal polymer composition of the present invention is shaped part, its microbicidal action is considered to be largely dependent on the silica gel based antimicrobial composition present near the surface of the shaped part, so it may be advisable to provide the shaped part with a multilayer structure and treat its outer layer to acquire a microbicidal activity. In the case of fibers, a core/sheath yarn may be prepared by a known conjugate fiber spinning technique, with the antimicrobial polymer composition of the present invention being used as the sheath component.
The antimicrobial polymer composition of the present invention comprising the silica gel based antimicrobial composition at least 0.2% by weight of the antimicrobial polymer composition and TBZ at least 0.03% by weight of the antimicrobial polymer composition keeps excellent biocidal ability against fungi for a long time and shows good weatherability. It shows little coloration or discoloration over time. Furthermore, since the antimicrobial polymer composition of the present invention has a good water-resistance, it shows little change in water or hot water over time.
By incorporating effective amount of at least one additive selected from the group consisting of titanium dioxide, zirconium oxide, cerium oxide and layer silicate into the present antimicrobial polymer composition, a discoloration of the antimicrobial polymer composition is further lowered and a weatherability is further improved. These advantageous effects are obtained by an addition at a few percentage by weight of antimicrobial polymer composition.
TBZ improves a discoloration and a weatherability and causes no adverse effects on antimicrobial ability of the silica gel based antimicrobial composition. Furthermore, the silica gel based antimicrobial composition causes no adverse effects on mildewcidal ability of TBZ. Accordingly, an incorporation of silica gel based antimicrobial composition and TBZ causes no inconvenience. A mildewcidal ability is strengthen by the incorporation, because both have mildeweidal ability.
The antimicrobial polymer composition of the present invention has the following advantages:
(a) The antimicrobial polymer composition comprising silica gel based antimicrobial composition, TBZ and polymer has an excellent discoloration resistance and weatherability.
(b) An incorporation of at least one additive selected from the group consisting of titanium oxide, zirconium oxide, cerium oxide and layer silicate to the present antimicrobial polymer composition further improves a discoloration resistance and a weatherability.
(c) The antimicrobial polymer composition in the above (a) or (b) have an excellent antimicrobial ability against fungi.
(d) The antimicrobial polymer composition has an excellent mildewcidal ability. Since it contains TBZ and silica gel based antimicrobial composition, both of which have mildewcidal ability.

The present invention is described in detail by working examples, however they are not intended to restrict the scope of the present invention.
An antimicrobial ability of the antimicrobial polymer composition was measured by the following "Drop method."
1) The tested bacterium or fungus
Escherichia coli (IFO 12734)
StaphyIococcus aureus (IFO 12732)
Aspergillus niger (IFO 4407)
2) Preparation of the suspension of the tested bacterium or fungus
The cells of Escherichia coli or Staphylococcus aureus that had been cultivated in Nutrient Agar (Oxoid) for 18-24 hours were suspended in sterile phosphate buffer at a concentration of from 10.sup.5 to 10.sup.6 cells/ml. To prepare a cell suspension of Aspergillus niger, the conidia of the Aspergillus niger that had been cultivated in a potato dextrose agar medium (available from Eiken Chemical Corp.) at 25.degree. C. for 7-10 days were suspended in sterile 0.005% dioctyl sodium sulfosuccinate aqueous solution and filtered with sterile gauze to prepare a suspension at a concentration of 10.sup.6 cells/ml.
3) Medium and cultivation condition
For Esehenchia coli or Staphylococcus aureus
Mueller Hinton Medium (Difco): 35.degree. C. for 2 days
For Aspergillus niger
Sabouraud Dextrose Agar (Difco): 25.degree. C. for 7 days
4) Preparation of the test piece
25 mm.times.25 mm.times.1.5 mm (thickness) sized test piece was cleaned with alcohol-impregnated cotton and air-dried. The obtained test piece was provided to the test.
5) Test procedure
0.3 ml of the suspension of E. coli, S. aureus or A. niger was dropped on a surface of the test piece. The test piece was stood for a given time. At 8, 12 and 24 hours later, a number of viable cells was counted by mixed plate culture method. In the tables 1-5, "<10" represents that a number of viable cells was lower than a limit of detection. The number represented in the tables 1-5 is a number of viable cells per test piece.
EXAMPLE 1
In this example, antimicrobial low density polyethylene (LDPE) compositions comprising antimicrobial composition at less than 1% by weight were prepared and the antimicrobial ability thereof were measured.
Sumikasen F101-3 available from Sumitomo Chemical Co.Ltd is used as LDPE. Bactenon AZ, which is a powdery antimicrobial composition having an antimicrobial coat of aluminosilicate on the surface of silica gel and said antimicrobial coat contains metal ions, is used as the silica gel based antimicrobial composition. Its water content was controlled below 1% by weight. A predetermined amount of Bectenon AZ, TBZ, zirconia(ZrO.sub.2) and talc were mixed with the LDPE. The obtained mixture was melted and kneaded at 195-210.degree. C. and molded.
The moldings were cut into test pieces sized 25 mm.times.25 mm and 1.5 mm thick. In the test pieces 1-1, 1-2 and C-1, Bactenon AZ containing 3.51% of Ag, 1.96% of Zn and 0.95% of Na and having 2.8 micro meters of Dav was used. Dav means an averaged diameter. In the test piece 1-3, Bactenon AZC containing 3.82% of Ag, 1.13% of Zn, 1.24% of Cu and 0.89% of Na and having 3.2 micro meters of Dav was used. The compositions of the prepared antimicrobial LDPE compositions are shown in the Table 1, where the test piece C-1 is a comparative example and 1-BL is a blank test piece containing no antimicrobial composition.
The antimicrobial LDPE compositions of the present invention show a good antimicrobial ability against S. aureus. TBZ, zirconia and talc do not interfere an antimicrobial ability of Bactenon AZ.
TABLE 1__________________________________________________________________________ Composition ofSample molded antimicrobial Number of viable cells (hrs.)No. polymer Fungus 0 12 24__________________________________________________________________________1-1 LDPE-Bactenon AZ, 0.7% S. aureus 9.4 .times. 10.sup.5 0 -- --ZrO.sub.2, 2%TBZ, 0.5%1-2 LDPE-Bactenon AZ, 0.7% S. aureus 9.4 .times. 10.sup.5 0 --Talc, 5%TBZ, 0.2%C-1 LDPE-Bactenon AZ, 0.7% S. aureus 9.4 .times. 10.sup.5 0 -- --ZrO.sub.2, 2% 1-BL LDPE plate S. aureus 9.4 .times. 10.sup.5 3.1 .times. 10.sup.5 -- (Blank: without anti- microbial composition)1-3 LDPE-Bactenon AZC, 0.5% S. aureus 9.2 .times. 10.sup.5 2.1 .times. 10.sup.4 8.3 .times. 10.sup.2Talc, 1%TBZ, 0.2% 1-BL LDPE plate S. aureus 9.2 .times. 10.sup.5 4.9 .times. 10.sup.5 2.3 .times. 10.sup.5 (Blank: without anti- microbial composition)__________________________________________________________________________
EXAMPLE 2
In this example, antimicrobial low density polyethylene (LDPE) compositions comprising antimicrobial composition at greater than 1% by weight were prepared and the antimicrobial ability thereof were measured.
Sumikasen F101-3 available from Sumitomo Chemical Co.Ltd. is used as LDPE. A predetermined amount of Bectenon AZ, TBZ and an optional titanium dioxide were mixed with the LDPE. The obtained mixture was melted and kneaded at 195-210.degree. C. and molded.
The moldings were cut into test pieces sized 25 mm.times.25 mm and 1.5 mm thick. In the test piece 2-1, Bactenon AZ containing 3.51% of Ag, 1.46% of Zn, 0.91% of Na and 1.02% of NH.sub.4 and having 3.3 micro meters of Dav was used. In the test pieces 2-2, 2-3 and 2-4, Bactenon AZ containing 3.21% of Ag, 1.45% of La and 1.16% of Na and having 3.2 micro meters of Dav was used. A water content of hese Bactenon was decreased below 1% by weight before use. The result of a measurement of an antimicrobial ability is shown in the Table 2. All test pieces of the present invention show a good antimicrobial ability against E. coli, where the test piece 2-BL is a blank test piece containing no antimicrobial composition and it shows no antimicrobial ability.
TABLE 2______________________________________ Composition of molded anti-Sample microbial Number of viable cells (hrs.)No. polymer Bacteria 0 8 24______________________________________2-1 LDPE-Bactenon E. Coli 1.0 .times. 10.sup.5 <10 <10 AZ, 2%TBZ, 0.5%2-2 LDPE-Bactenon E. Coli 1.0 .times. 10.sup.5 -- 7.6 .times. 10.sup.2 AZ, 1%TBZ, 0.2%2-3 LDPE-Bactenon E. Coli 1.0 .times. 10.sup.5 <10 <10 AZ, 2%TBZ, 0.2%2-4 LDPE-Bactenon E. Coli 1.0 .times. 10.sup.5 <10 <10 AZ, 2%TBZ, 0.2% --Ti0.sub.2, 1% 2-BL LDPE plate E. Coli 1.0 .times. 10.sup.5 6.7 .times. 10.sup.4 2.2 .times. 10.sup.5 (Blank: without antimicrobial composition)______________________________________
EXAMPLE 3
In this example, antimicrobial polypropylene (PP) compositions were prepared and the antimicrobial ability thereof were measured.
K-1008N available from Chisso Corp., Hipole J740 available from Mitsui Petrochemical Industries, Ltd. and 7510AG available from Mitsubishi Rayon Co.,Ltd are used as polypropylene. A predetermined amount of Bectenon having a water content below 1% by weight, TBZ, and optional zirconia, talc and cerium oxide were mixed with PP. The obtained mixture was melted and kneaded at 185-190.degree. C. and molded. The moldings were cut into test pieces sized 25 mm.times.25 mm and 1.5 mm thick.
In the test pieces 3-1, 3-2, 3-3 and 3-4, K-1008N was used as PP and Bactenon AZ containing 3.51% of Ag, 1.91% of Zn and 0.95% of Na and having 2.8 micro meters of Dav was used. All of the test pieces show a good antimicrobial ability against E. coli as represented in the Table 3A, where the test piece 3-BL is a blank test piece containing no antimicrobial composition and it shows no antimicrobial ability.
In the test piece 3-5, Hipole J740 was used as PP, while in the test pieces 3-6 and 3-7, 7510AG was used as PP, while in the test pieces 3-5 and 3-6, Bactenon AZ containing 3.62% of Ag, 2.01% of Zn and 1.12% of Na and having 2.9 micro meters of Dav was used. In the test piece 3-7, Bactenon AZC containing 3.82% of Ag, 1.13% of Zn, 1.24% of Cu and 0.89% of Na and having 3.2 micro meters of Dav was used. All of the test pieces show a good antimicrobial ability against S. aureus as represented in the Table 3B.
TABLE 3A______________________________________ Composition of molded anti-Sample microbial Number of viable cells (hrs.)No. polymer Bacteria 0 8 24______________________________________3-1 PP-Bactenon AZ, E. Coli 3.8 .times. 10.sup.5 <10 <10 2%TBZ, 0.2%3-2 PP-Bactenon AZ, E. Coli 3.8 .times. 10.sup.5 3.6 .times. 10.sup.2 <10 3%TBZ, 0.2%3-3 PP-Bactenon AZ, E. Coli 3.8 .times. 10.sup.5 <10 <10 3%TBZ, 0.5%3-4 PP-Bactenon AZ, E. Coli 3.8 .times. 10.sup.5 <10 <10 3%TBZ, 0.3% --ZrO.sub.2, 1% 3-BL PP plate E. Coli 3.8 .times. 10.sup.5 4.1 .times. 10.sup.5 3.0 .times. 10.sup.5 (Blank: without antimicrobial composition)______________________________________
TABLE 3B______________________________________ Number of viableSample Composition of molded cells (hrs)No. antimicrobial polymer Bacteria 0 24______________________________________3-5 PP-Bactenon AZ, 2% S. aureus 9.2 .times. 10.sup.5 5.2 .times. 10.sup.1 --Ti0.sub.2, 0.2%TBZ, 0.2%3-6 PP-Bactenon AZ, 2% S. aureus 9.2 .times. 10.sup.5 <10TBZ, 0.1%Talc, 1%3-7 PP-Bactenon AZC, 2% S. aureus 9.2 .times. 10.sup.5 7.2 .times. 10.sup.1TBZ, 0.5% --Ce0.sub.2, 1%______________________________________
EXAMPLE 4
In this example, antimicrobial polycarbonate (PC) compositions were prepared and the antimicrobial ability thereof was measured.
L1225W available from Teijin Kasei Corp. is used as polycarbonate. A predetermined amount of Bectenon AZ having a water content below 1% by weight, TBZ, and optional titanium dioxide were mixed with PC. The obtained mixture was melted and kneaded at 280-290.degree. C. and molded. The moldings were cut into test pieces sized 25 mm.times.25 mm and 1.5 mm thick. In this example, Bactenon AZ containing 3.57% of Ag, 1.96% of Zn and 0.95% of Na and having 2.8 micro meters of Dav was used. The test piece C-2 is a comparative example and 4-BL is a blank test piece containing no antimicrobial composition.
The antimicrobial PC compositions of the present invention show a good antimicrobial ability against S. aureus. As both 4-2 and C-2 show a good antimicrobial ability against S. aureus, it is obvious that TBZ does not interfere an antimicrobial ability of Bactenon AZ.
TABLE 4______________________________________ Number of viableSample Composition of molded cells (hrs)No. antimicrobial polymer Bacteria 0 24______________________________________C-2 PC-Bactenon AZ, 3% S. aureus 2.9 .times. 10.sup.5 <10 --Ti0.sub.2, 0.5%4-2 PC-Bactenon AZ, 3% S. aureus 2.9 .times. 10.sup.5 <10 --Ti0.sub.2, 0.5%TBZ, 0.2% 4-BL PC plate S. aureus 2.9 .times. 10.sup.5 2.0 .times. 10.sup.5 (Blank: without anti- microbial composition)______________________________________
EXAMPLE 5
In this example, antimicrobial ABS compositions were prepared and the antimicrobial ability thereof were measured.
TS20P available from Mitsubishi Rayon Co., Ltd. is used as ABS resin.
A predetermined amount of Bectenon AZ having a water content below 1% by weight, TBZ, and optional titanium dioxide were mixed with the ABS resin. The obtained mixture was melted and kneaded at 245-250.degree. C. and molded. The moldings were cut into test pieces sized 25 mm.times.25 mm and 1.5 mm thick. In this example, Bactenon AZ containing 3.39% of Ag, 1.93% of Zn and 1.01% of Na and having 2.9 micro meters of Dav was used.
The test piece C-3 is a comparative example.
As both of 5-2 and 5-3 show a good antimicrobial ability against A. niger, it is obvious that TBZ and titanium dioxide do not interfere an antimicrobial ability of Bactenon AZ.
TABLE 5______________________________________ Composition of molded anti-Sample microbial Number of viable cells (hrs.)No. polymer Fungus 0 8 12______________________________________C-3 ABS-Bactenon A. niger 6.7 .times. 10.sup.5 8.7 .times. 10.sup.4 6.5 .times. 10.sup.3 AZ, 2%5-2 ABS-Bactenon A. niger 6.7 .times. 10.sup.5 1.4 .times. 10.sup.2 <10 AZ, 3%TBZ, 1%5-3 ABS-Bactenon A. niger 6.7 .times. 10.sup.5 -- 2.4 .times. 10.sup.3 AZ, 2.5%TBZ, 2% --Ti0.sub.2, 0.3%______________________________________
EXAMPLE 6
This example is a daylight exposure test of the present antimicrobial polymer composition.
The antimicrobial polypropylene compositions were prepared in accordance with the procedure of the example 3. The compositions thereof are shown in the Table 6. The obtained moldings were cut into test pieces sized 50 mm.times.50 mm and 1.5 mm thick. The test pieces were exposed to sun for 6 months. In this example, Bactenon AZ containing 3.51% of Ag, 1.96% of Zn and 0.95% of Na and having 2.8 micro meters of Dav was used. A water content of the Bactenon was controlled below 1% by weight before use.
An initial color of the test pieces P-1 to P-6 were creamy white and the color did not change after the exposure test. On the other hand, a color of the comparative example C-1 changed from an initial color of white to gray with time.
An initial color of the test piece P-7 was creamy white and the color did not change after the exposure test. On the other hand, a color of the comparative example C-2 changed from an initial color of white to brown with time and became dark brown after 2 months.
An initial color of the test piece P-8 was white with pale yellow and the color did not change after the exposure test. A color of pale yellow is the color of contained TBZ. On the other hand, a color of the comparative example C-3 changed from an initial color of white to dark brown with time.
It is obvious that the antimicrobial polymer composition of the present invention has a superior discoloration resistance and weatherability to those of prior arts.
TABLE 6__________________________________________________________________________Sample Composition of InitialNo. molded antimicrobial polymer color Change with time after molding__________________________________________________________________________P-1 LDPE(F101-3)-Bactenon AZ, 0.7% creamy no change was observed --ZrO.sub.2, 2%-TBZ, 0.5% whiteP-2 LDPE(F101-3)-Bactenon AZ, 2% creamy no change was observed --Zr0.sub.2, 2%-TBZ, 0.5% whiteP-3 LDPE(F101-3)-Bactenon AZ, 0.7% creamy no change was observedTBZ, 0.18% whiteC-1 LDPE(F101-3)-Bactenon AZ, 0.7% white color changed to gray and --Zr0.sub.2, 2% a degree of the coloring became stronger with timeP-4 LDPE(F101-3)-Bactenon AZ, 2% creamy no change was observedTalc, 5%-TBZ, 0.5% whiteP-5 LDPE(F101-3)-Bactenon AZ, 2% creamy no change was observed --TiO.sub.2, 1%-TBZ, 0.3% whiteP-6 LDPE(F101-3)-Bactenon AZ, 0.7% creamy no change was observed --Ce0.sub.2, 1%-TBZ, 0.5% whiteP-7 PP(J740)-Bactenon AZ, 2% creamy no change was observedTBZ, 0.5% whiteC-2 PP(J740)-Bactenon AZ, 2% white color changed to brown with time and became dark brown after two monthsP-8 PP(7510AG)-Bactenon AZ, 2% creamy no change was observedTBZ, 0.5%--Ti0.sub.2, 0.5% whiteC-3 PP(7510AG)-Bactenon AZ, 2% white color changed to brown with time and became dark brown after two months__________________________________________________________________________
EXAMPLE 7
This example shows that the antimicrobial composition contained in the antimicrobial polymer composition of the present invention does not interfere a mildewcidal ability of TBZ.
The antimicrobial LDPE composition was prepared in accordance with the procedure of the example 1 employing Sumikasen F101-3 as LDPE. The antimicrobial LDPE composition comprises 3% by weight of Bactenon AZ and 0.4% by weight of TBZ. The obtained moldings were cut into test pieces sized 50 mm.times.50 mm and 1.5 mm thick. In this example, Bactenon AZ containing 3.51% of Ag, 1.96% of Zn and 0.95% of Na and having 2.8 micro meters of Dav was used. A water content of the Bactenon was controlled below 1% by weight before use. For a blank test, the sample without Bactenon was prepared.
A measurement of mildeweidal ability was carried out in accordance with the procedure defined in the Japanese Industrial Standard (JIS Z 2911) and described in the following.
1) The Tested Fungus
Aspergillus niger (IFO-4407)
Penicillium funiculosum (IFO-6345)
Chaetomium globosum (IFO-6347)
Gliocladium virens (IFO-6355)
Aureobasidium pulluland (IFO-6353)
2) Preparation of the Suspension of the Tested Fungus
Each of the fungi was cultivated in a potato dextrose agar medium until enough spores were obtained. Each of the fungi was suspended in sterile 0.005% dioctyl sodium sulfosuccinate aqueous solution and form a suspension of each fungus. The same amount of each suspension was mixed to prepare a suspension of mixed spores.
3) Procedure of the Test
a) A sample was put in a laboratory dish and spray the suspension of mixed spores to wet a surface of the sample in accordance with the JIS methods.
b) The dish was kept at 29.degree. C. and relative humidity 85% for 30 days. A growth of mycelium was visually observed. The result is shown in the Table 7.
It is obvious from the result that the antimicrobial composition contained in the antimicrobial polymer composition of the present invention does not interfere a mildeweidal ability of TBZ.
TABLE 7______________________________________Composition ofmolded antimicrobial polymer Result______________________________________LDPE-Bactenon AZ, 3%-TBZ, No growth of mycelium was observed0.4% at all of four surfaces of the test piecesLDPE-Blank A growth of mycelium was observed(without antimicrobial at all of four surfaces ofcomposition) the test pieces______________________________________
EXAMPLE 8
In this example, polyvinyl chloride (PVC), melamine resin(MEL) and polystyrene (PS) are used as polymer of the antimicrobial composition.
PVC is a halogenated organic polymer. MEL is an example of thermosetting resin. PS is one of the typical thermoplastic resins.
In the samples 8-1, 8-2 and 8-3, PVC was used as a polymer. A powdery PVC having a degree of polymerization of about 1,000 was used as a raw material. Di-2-ethylhexylphthalate was used as a plasticizer at an amount of about 15 wt %. Bactenon AZ and Zn, which are powdery antimicrobial compositions having an antimicrobial coat of aluminosilicate on the surface of silica gel and said antimicrobial coat contains metal ions, are used as the silica gel based antimicrobial compositions. Bactenon AZ contains 3.5% of Ag and 2.3% of Zn and has 2.94 micro meters of Dav. Bactenon Zn contains 3.1% of Zn and has 2.78 micro meters of Dav. The molding was carried out at from 140 to 145.degree. C. The moldings were cut into test pieces sized 50 mm.times.50 mm and 2 mm thick.
In the samples 9-1, 9-2 and 9-3, MEL was used as a polymer. Molding was carried out at from 167 to 170.degree. C. for 150 seconds. The moldings were cut into test pieces sized 50 mm.times.50 mm and 2 mm thick.
In the samples 10-1, 10-2 and 10-3, PS was used as a polymer. Molding was carried out at about 230.degree. C. The moldings were cut into test pieces sized 50 mm.times.50 mm and 1.5 mm thick. The samples 8-1, 9-1 and 10-1 were blank samples, which do not contain antimicrobial compound and TBZ. The samples 8-2, 9-2 and 10-2 were comparative samples, which contain antimicrobial compound solely. The samples 8-3, 9-3 and 10-3 were working examples of the present invention, which contain both antimicrobial compound and TBZ.
The results of antimicrobial ability test were shown in Table 8. It is revealed that antimicrobial ability was not adversely affected by an addition of TBZ.
A daylight exposure test was carried out for all of the above samples. For PVC and MEL the test piece was exposed under daylight for 3 months. For PS, the test piece was exposed under daylight for 4 months. The results were shown in Table 9. It is revealed that an addition of antimicrobial compound adversely affects a weatherability. An addition of TBZ recovers said adversely effects and the weatherability of the samples 8-3, 9-3 and 10-3 were as good as that of the samples 8-1, 9-1 and 10-1, respectively.
TABLE 8______________________________________ Number of viableSample Composition of molded cells (hrs)No. antimicrobial polymer Bacteria 0 24______________________________________8-1 PVC plate E. coli 4.8 .times. 10.sup.5 6.4 .times. 10.sup.5 (Blank; without antimicrobial composition)8-2 PVC-Bactenon Zn, 1.0% E. coli 4.8 .times. 10.sup.5 <108-3 PVC-Bactenon Zn, 1.0% E. coli 4.8 .times. 10.sup.5 <10TBZ, 0.1%9-1 MEL plate E. coli 7.6 .times. 10.sup.5 2.2 .times. 10.sup.6 (Blank; without antimicrobial composition)9-2 MEL-Bactenon Zn, 5.0% E. coli 7.6 .times. 10.sup.5 <109-3 MEL-Bactenon Zn, 5.0% E. coli 7.6 .times. 10.sup.5 <10TBZ, 0.5%10-1 PS plate E. coli 2.4 .times. 10.sup.5 2.1 .times. 10.sup.5 (Blank; without antimicrobial composition)10-2 PS-Bactenon AZ, 3.0% E. coli 2.4 .times. 10.sup.5 <1010-3 PS-Bactenon AZ, 3.0% E. coli 2.4 .times. 10.sup.5 <10TBZ, 0.3%______________________________________
TABLE 9______________________________________Sample No. Initial color Change with time after molding______________________________________8-1 gray white no change was observed8-2 gray white became yellowish gray white8-3 gray white no change was observed9-1 white no change was observed9-2 white became yellowish white9-3 white no change was observed10-1 white no change was observed10-2 white became gray white10-3 white no change was observed______________________________________

Number	Name	Date	Kind
5413789	Hagiwara	May 1995
5698212	Hagiwara et al.	Dec 1997

Antimicrobial polymer composition

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