Patent Application
20100233326
The present invention relates to an antibacterial film, an antibacterial sheet, and the like with laminate structure imparted with an antibacterial property, and in particular, the present invention relates to an antibacterial laminate preferably used as packaging bags or food-packaging films capable of preventing propagation of bacteria and the like and of maintaining quality when packaging snacks such as potato chips and sweets such as biscuits.
With the recent increase in the requests for hygiene, products with antibacterial properties and the like have been demanded, and such demands are striking, particularly for table wares and wrapping materials for foods. With such these backgrounds, as packaging materials for foods with antibacterial properties, proposals have been made for the packaging materials using the laminating film that has layers constituted of thermoplastic resins including organic or inorganic antibacterial agents on its surface (Patent Document 1: Japan Unexamined Patent Publication 2005-187062). However, since these packaging materials are used with the surface layer that includes the antibacterial agent inside of the package, that is, these packaging materials are used toward the food side, there is high possibility that the antibacterial agents directly contact with foods and there lies a concern for safety when organic antibacterial agents are used. In addition, when the inorganic antibacterial agents are used, since the antibacterial agents are exposed on the surface, the antibacterial capability is degraded due to the falling-off or oxidization of the antibacterial agents and also, aesthetic feeling is degraded due to the color changes by the excessive ionization of the antibacterial metal component, and thus, they are not suitable for packaging foods.
Therefore, the object of the present invention is to provide the antibacterial laminate used for packaging materials for foods with at least either of the antibacterial property and the antifungal property, and to provide the antibacterial laminate that does not directly contact with the packaged materials or air.
In order to solve the above mentioned problems, first, it is necessary that the layer having the antibacterial agents does not directly contact with air. For this, attention has been made not to provide the layer having antibacterial agents on the outermost surface and not to provide portions in which the layer having the antibacterial agents is exposed to the outside air, for example, by penetration pores. On the other hand, in order to ensure the antibacterial property of the laminate, it is necessary that the antibacterial agents in the layer inside of the laminate function on the surface of the laminate. Thus, the inventors have considered that the stable antibacterial function over a long term can be imparted to the laminate by the sustained release effect by designing the laminate so that the antibacterial agents that are liberated from the layer that has the antibacterial agents (hereinafter called “antibacterial layer”) are gradually emitted toward the laminate surface. And they have found the laminate capable of showing the effect of antibacterial function derived from the antibacterial layer on the laminate surface even when the antibacterial layer is coated, and have accomplished the present invention.
In the antibacterial laminate with at least either of the antibacterial property and the antifungal property, the antibacterial laminate of the present invention has the most important characteristics in that it is at least constituted of the substrate layer including a polymer film or paper, the antibacterial layer with a vapor deposition metal having at least either of the antibacterial property and the antifungal property, and the coating layer for coating the antibacterial layer, wherein the antibacterial layer is formed between the substrate layer and the coating layer and the coating layer is a substantially poreless polymer coated film.
It is preferable that the substrate layer is a stretched polymer film or the laminate of the stretched polymer film and the non-stretched polymer film and that in such a laminate, the antibacterial layer is formed in the side of the non-stretched polymer side.
It is preferable that a thickness of the coating layer is 0.1 to 1.0 μm.
That the coating layer is substantially poreless means that there is no pore whose diameter is not less than 0.1 μm.
It is preferable that the coating layer is a polyester resin, a cellulose derivative, an acrylic resin, an epoxy resin, an urethane resin, a phthalic acid resin, an amino resin, or a mixture of any of the above mentioned resins. In particular, it is preferable that the coating layer is constituted of the polyester resin, the cellulose derivative resin, or the mixture of any of the above mentioned resins.
It is preferable that the coating layer is formed by coating a polymer solution on the antibacterial layer.
Further, between the substrate layer and the antibacterial layer, it may have a metal deposition layer in which a metal or a metal oxide that has no antibacterial and antifungal property.
It is preferable that the metal that has at least either of the antibacterial property and the antifungal property is silver.
It is preferable that the metal or the metal oxide that has no antibacterial or antifungal property is aluminum, silica, or alumina.
It is preferable that the substrate layer is the stretched film constituted of a polyester, a polypropylene, or a polylactic acid.
It is preferable that at least any of the resins is included between the substrate layer and the antibacterial layer, said resin being selected from a group of a polyester resin, an acrylic resin, an urethane resin, an epoxy resin, a melamine resin, a polyamide resin and polyvinyl alcohol resin.
The antibacterial laminate of the present invention is effective for food packages or containers tightly packed or sealed, in particular, such as food packaging films, food packaging bags, packaging bags or containers, sheet-like strips sealed in the food packaging bags or food containers or attached to the wall surfaces. When used as food packaging bags, it is preferable to make long-scaled packaging materials capable of further laminating the sealant layer constituted of polymers with low melting points on certain portions of the coating layers of the antibacterial laminate of the present invention thereby being able to make the certain portions in the vertical direction and the horizontal direction to seal surfaces when the bags are formed.
Further, the antibacterial laminates of the present invention are effective for medical use such as sheet-like strips sealed in medical bags including transfusion bags, urine-collecting bags, peritoneal dialysis bags or the sheet-like strips attached to the wall surfaces, medical charts, consultation tickets, and the like.
By the present invention, the antibacterial laminated can be obtained that has stable antibacterial function and antifungal function over a long term without generating color changes and the like due to oxidization even when contacting with outside air.
Also, when the coating layer has a certain degree of oxygen permeability and when the metal of the metal deposition film has an oxygen trapping property by oxidization, the antibacterial laminate of the present invention has gas barrier property as well as antibacterial function and antifungal function, and therefore, it is further excellent when used as packaging materials.
Further, when the antibacterial layer is constituted of vapor deposition silver and is formed with a thickness of 100 to 200 Å, the vapor deposition layer has the antibacterial property and passes through visible light, and therefore, the antibacterial laminate of the present invention can form the packaging bag with the foods therein observed.
The utensils used in the medical scenes such as medical charts and consultation tickets utilizing the antibacterial laminates of the present invention and medical bags and the like such as transfusion bags or urine-collecting bags and the like with the sheet-like strips of antibacterial laminate sealed or attached are effective for preventing hospital infection.
1 shows a coating layer
2 shows an antibacterial layer
3 shows an adhesive layer
4 shows a substrate layer
5 shows a sealant layer
(Basic Structure of Laminate)
The antibacterial laminate of the present invention is at least provided with a coating layer (1), an antibacterial layer (2), and a substrate layer (4). Further, in order to surely laminate the antibacterial layer (2) on the substrate layer (4), as shown in the schematic sectional view in
In addition, although further providing the additional layers on the front surface or the rear surface of the antibacterial laminate is not prohibited, it should be noted that when the additional layers are provided over a whole surface on the coating layer (1), the effect of the present invention cannot be achieved. In other words, for example, when used as the food packaging bag for sealing the foods therein, it is preferable that at least a part of the coating layer (1) is exposed at the laminate's surface that contacts with the food as the outermost layer (viewed as a bag structure, the innermost layer) so that the part of the coating layer (1) can contact with sealed foods.
(Coating Layer)
The coating layer contributes to the sustained release property of the antibacterial agents in the antibacterial laminate and the coating layer is a substantially poreless polymer coated film obtained by the coating of a coating liquid. When further detailed explanation on “substantially poreless” should be required, it means that there is no pore present whose diameter is not less than 0.1 μm. When there are pores whose diameter of not less than 0.1 μm present in the coating layer (1), there is a concern, for example, that the food sealed in the food packaging bag using the antibacterial laminate of the present invention and the antibacterial layer (2) directly contacts with each other, and by this, there is a concern that the metal constituting the antibacterial layer (2) adheres to the sealed food.
As polymers used as materials of the coating layer, the resins harmless to human bodies even when contacting with food are used. In particular, such resins as polyester resins, cellulose derivative resins, acrylic resins, epoxy resins, urethane resins, phthalic resins, amino resins, and the like can be used either alone or in combinations. Further, it is preferable that the polyester resins or cellulose derivative resins are used alone or in combinations.
As polyester resins, copolymers of polybasic acid and polyvalent alcohol are exemplified. As polybasic acid, adipic acid, succinic acid, isophthalic acid, terephthalic acid, phthalic anhydride, maleic anhydride, trimellitic acid, hexahydrophthalic anhydride, and the like are exemplified. As polyvalent alcohol, ethylene glycol, propylene glycol, glycerin, trimethylol propane, neopentyl glycol, 1,6hexanediol, pentaerythritol, sorbitol, and the like are exemplified.
In the present invention, it is preferable to use amorphous polyester soluble to the organic solvent obtained by copolymerizing these polybasic acids and polyvalent alcohol. To be specific, it is preferable to use polyester disclosed in the patent document 2 (Unexamined Patent Publication 2005-162960) (copolymerized polymer of terephthalic acid, isophthalic acid and ethylene glycol, neopentyl glycol, and the like) and polyester marketed under the name of “PYLON” (manufactured by TOYOBO CO., LTD.).
As cellulose derivative resins, nitro cellulose, cellulose acetate butyrate, cellulose acetate, cellulose acetate propionate, and the like can be exemplified, and in particular, nitro cellulose, cellulose acetate butyrate are preferable and nitro cellulose is further preferable.
As acrylic resins, (meth)acrylic resins obtained by copolymerizing derivatives of (meth)acrylic acid (methyl(meth)acrylate, n-propyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, (meth)acryl amide, and the like) are exemplified and every kind of (meth)acrylic resins used for coating can be used.
As epoxy resins, glycidyl ether type epoxy resin (bisphenol A glycidyl ether and the like), glycidyl ester type epoxy resin, glycidyl amino type epoxy resin, cyclic oxyrane type epoxy resin, and the like can be exemplified.
As urethane resins, the urethane resins obtained by reacting each kind of isocyanate compounds (hexamethylene diisocyanate, cyclohexane diisocyanate, and the like) with each kind of polyols (polyester polyol, polyether polyol, and the like) can be exemplified.
As phthalic acid resins, the resins obtained by condensation of each kind of polybasic acids (phthalic anhydride, adipic acid, and the like) and polyvalent alcohols (glycerin, pentaerythritol, and the like) can be exemplified.
As amino resins, the resins obtained by adding formaldehyde to each kind of amino compounds (melamine, guanamine, urea, and the like) and then modifying the addition products (methylol and the like) with alcohol can be used. To be specific, melamine resins, benzoguanamine resins, acetoguanamine resins, and urea resin used for coatings can be exemplified. Among them, melamine resins and benzoguanamine resins are preferable.
In the present invention, the above mentioned resins can be used in combinations as well.
In the present invention, other than the resins exemplified above, it is possible to use modified products of these resins, for example, acryl modified polyester resins, urethane modified polyester resins, urethane modified alkyd resins, and epoxy modified polyester resins.
It is necessary that a thickness of the coating layer is within the range of 0.1 to 1.0 μm and more preferably, it is 0.2 to 0.5 μm. When the thickness is less than 0.1 μm, a formation of the coated film becomes difficult and there is a concern that the antibacterial agents penetrate the coating layer and are exposed to the laminate surface, and when the thickness exceeds 1.0 μm, the antibacterial agents or antibacterial metal ions liberated from the antibacterial layer cannot reach to the laminate surface, thereby prohibiting the satisfactory antibacterial function.
(Antibacterial Layer)
The antibacterial layer (2) is a metal deposition film in which the metals with at least either of the antibacterial property and the antifungal property (hereinafter simply called “antibacterial metal”) are deposited by such methods as vacuum deposition methods or ion deposition methods. This is because that ionized antibacterial metals are liable to move to the surfaces of the laminates and that it is advantageous to obtain the desired antibacterial effect. As antibacterial metals, silver, gold, platinum, copper, aluminum, titanium, nickel, tin, zinc, palladium, bismuth, and chrome and the alloys thereof can be exemplified. Also, the film thickness of the vapor deposition film of the antibacterial layers is about 100 to 1000 Å.
Among the above mentioned antibacterial metals, it is preferable to use silver with preferable property for every safety, antibacterial property, and antifungal property. When the silver vapor deposition layer is used, it has both antibacterial property and antifungal property even when it has a thickness of 100 Å. In addition, it has also been found that even when the silver deposition thickness is as thin as 100 Å, it shows a satisfactory gas barrier property from the practical viewpoint. In particular, when the silver deposition thickness is 550 Å, the gas barrier property becomes very high. Such a high gas barrier property is considered to be based on the fact that the silver activated by the deposition easily absorbs oxygen thereby becoming silver oxide. On the other hand, when the thickness of the silver deposition is not greater than 200 Å, transparent or translucent films can be prepared as antibacterial laminates, and therefore, the contents can be observed from outside in a tightly packed state and thus, the application range of the antibacterial laminate of the present invention can be enlarged.
Further, the antibacterial layer (2) can also be formed by vapor depositing the metal other than the already mentioned antibacterial metal or metal oxide with no antibacterial property or antifungal property on the substrate layer (4) or a adhesive layer (3) (not illustrated), further followed by depositing the antibacterial metal thereon. As preferable metals or metal oxides that have neither antibacterial property nor antifungal property, aluminum, silica, or alumina can be exemplified. It is preferable that these vapor deposition layers (3) are formed within the range of 200 to 1500 Å.
(Adhesive Layer)
An adhesive layer (3) plays a role as an anchor coating agent since the antibacterial layer (2) is a metal deposition film. As resins used for the adhesive layer (3), polyester resins, acrylic resins, urethane resins, epoxy resins, melamine resins, polyamide resins, polyvinyl alcohol resins, and the like used alone or in combinations can be exemplified. The adhesive layer (3) is formed by coating these resins as adhesive agents on the substrate layer (4). In addition, although these resins can be coated as the adhesives as they are, two-component types can be formed using isocyanate and the like as a curing agent and be coated, and it is particularly preferable to form the adhesive layer (3) by coating adhesive agents of polyester/isocyanate.
(Substrate Layer)
A substrate layer (4) imparts basic strength to the antibacterial laminate. Further, in the antibacterial laminate of the present invention, the antibacterial layer (2) is formed by vacuum deposition methods or ion deposition methods on the substrate layer (4) interposing the adhesive layer (3). Therefore, as materials used for the substrate layer (4), it is preferable to use layers formed of heat resistant polymer or paper. As specific polymer materials, polyethylene terephthalate (PET) films, polypropylene films, PVA films, polyamide films, polylactic acid films, and the like can be used.
As polymer materials used for the substrate layer (4), although non-stretched polymer films can be used alone, it is more preferable to use strong stretched polymer films. As the stretched films, either of monoaxially stretched films and biaxially stretched films may be used.
Or, it is also preferable to prepare the laminate of the stretched polymer film and the non-stretched polymer film. In this case, it is preferable to form the antibacterial layer (2) in the side of the non-stretched polymer by vapor deposition. To be specific, the substrate layer (4) is prepared by laminating the non-stretched polymer layer on the stretched polymer film and the antibacterial layer (2) is formed by the vapor deposition from the non-stretched polymer layer side and further, by forming the coating layer (1) on the antibacterial layer, thereby preparing the antibacterial laminate of the present invention. It is preferable to constitute the substrate layer of the laminate of the stretched polymer film and the non-stretched polymer film particularly when the antibacterial laminate of the present invention is used as a packaging material for forming the packaging bag. In other words, by making the non-stretched polymer film a sealant film, and then by masking the to-be-sealed portions among the non-stretched polymer film so as to prevent vapor deposition of the antibacterial layer, or by peeling off the deposition layer of the to-be sealed portions after the whole deposition, the heat-sealable packaging material in the sealed surface can be prepared. The packaging bags excellent in the antibacterial property or antifungal property can be formed of the packaging materials prepared as above.
As examples of the preferably used non-stretched polymers, polypropylene, polyethylene terephthalate, polylactic acid, and the like can be exemplified.
It is preferable, that the thickness of the substrate layer (4) in the present invention is within the range of 10 to 1000 μm. It is preferable that the thickness of the substrate layer is selected within the range of 10 to 200 μm particularly when the antibacterial laminate of the present invention is used for the food packaging bag for packaging.
(Use)
Since the antibacterial laminate of the present invention can show the antibacterial property without directly contacting with the antibacterial layer, its safety is high. Also, the antibacterial laminate of the present invention can show the antifungal property and the oxygen barrier property as well. The antibacterial laminate of the present invention with such characteristics can be applicable to various uses. Further, depending on the thickness of the antibacterial laminate layers, the laminate can be made into a transparent or a translucent film, and therefore, it is preferable for the uses for acknowledging the substrate or contents through the antibacterial laminate. As specific applications, the followings can be exemplified.
[1. Food Packaging Bag]
The antibacterial laminate can be used as a starting laminated film to prepare a food packaging bag for packaging such as pillow type bags, square bags with gussets or rectangular sealed bags and the like. It is preferable that the laminating film has a thickness of 30 to 100 μm as a whole. In addition, in order to secure the antibacterial property in the bag, the inside surface of the bag should be the coating layer and therefore, the sealant layer is laminated only on the portions used for bonding for producing the bag when the sealant layer for producing the bag is provided on the coating layer. In
As methods for making the antibacterial laminate of the present invention into the food packaging bag, for example, the methods comprising preparing the long-scaled packaging materials coated with polymer that is to be a sealant layer at the predetermined sealed portions (vertical direction, horizontal direction) of the antibacterial laminate of the present invention, supplying the above structured long-scaled packaging materials to the packaging machine thereby shaping the film into tubular, while at the same time, supplying the food from the apex and performing vertical sealing and horizontal sealing, thereby forming into the food packaging bag can be exemplified.
As materials used for the sealant layer, polymer with a low melting point, low density polyethylene, copolymer of propylene and other olefin, non-stretched polypropylene, ethylene vinyl acetate resin and the like can be exemplified.
Foods sealed in the food packaging bag enjoy benefit of the antibacterial or antifungal effect of the antibacterial layer via the coating layer. Examples of the sealed foods include snacks such as potato chips, rice crackers (dried rice crackers and wet rice crackers) and sweets such as biscuits, sponge cakes and the like, and the food packaging bags using the antibacterial laminate of the present invention can preserve these sealed foods for a long time. In particular, the food packaging bag using the antibacterial laminate of the present invention can preserve even the foods that contain water such as sponge cakes or wet rice crackers without being contaminated by bacteria or molds.
Further, since the coating layer is present, the antibacterial and the antifungal property is maintained without letting the deposited metal, particularly silver, in the antibacterial layer fall off and even without color changes due to oxygen or small amount of SO2 contained in the air.
[2. Sheet-Like Strip Sealed in or Bonded to the Package for Foods]
In general, a drying agent and a deoxidizer are contained in the packaging bag for sealing the foods. However, the packaging bag with a sheet-like strip of the antibacterial laminate of the present invention sealed in or bonded to the inner side can be used as the food-sealed packaging bag without sealing in such a deoxidizer. Likewise, the above mentioned sheet-like antibacterial laminate can be used sealed in or bonded to the inner side of the food containers in which cupped noodles are tightly packed or sealed in.
When the antibacterial laminate of the present invention is used as the sheet-like strip, those formed with the antibacterial layer and the coating layer on paper or stretched films maybe laminated to a plastic sheet with thickness as further required.
The antibacterial laminate of the present invention is used by cutting it into an appropriate size in order to seal it in the packaging bag or to bond it to the inner side of the packaging bag. Sealing of the antibacterial laminate of the present invention to the packaging bag is made by forming the packaging bag by the bag making-packaging machine with each strip being added when the food measured by one package by a weighing apparatus provided on the packaging machine is supplied to the packaging machine.
On the other hand, in order to form the packaging bag to which the laminate strip of the present invention is bonded, the food packaging bag can be formed by laminating the strip to the portions on which the inner surface of the bag is formed of the general packaging material film except for the predetermined sealed portions so that the coating layer side contacts with the food and by supplying the laminated packaging material film to the bag making-packaging machine thereby forming the food packaging bag. In addition, generally, in the packaging material film, there is a substrate layer at the outer side and a sealant layer at the inner side and at the rear side of the substrate layer, a printing layer and a deposition layer are formed and on the deposition layer surface, the sealant layer film is formed laminatedly interposing the adhesive or extrude polyethylene.
[3. Medical Bag, Medical Chart, Consultation Ticket]
Since the antibacterial laminates of the present invention themselves used as the substrates or the medical bags such as transfusion bags bonded to some substrate can safely show the antibacterial property, they can prevent hospital infection.
Further, sometimes, not only the medical bags but also those used in the medical field such as medical charts and the like are not fully sterilized. The medical charts, consultation tickets formed of the antibacterial laminates of the present invention themselves have antibacterial property, which shows great effect in preventing hospital infection.
When the medical bags such as transfusion bags, urine-collecting bags, peritoneal dialysis bags and a like are made of the antibacterial laminate of the present invention, as in the case of food packaging bags, the antibacterial layer with the antibacterial or the antifungal metal deposited on polypropylene or polyester film is formed, the coating layer is formed thereupon to obtain the laminated film, and further, the medical bags are formed using the laminated film. In forming the medical bags, by forming the sealant layer in the sealed portions of the laminated film as in the case of the food packaging bags, and by sealing them with this sealant layer, the medical bags can be produced.
Also, the antibacterial laminate of the present invention may be bonded to the inner side surface of the medical bags as in the case of the sheet-like strips.
The consultation tickets made of the antibacterial laminate of the present invention can be obtained by forming the antibacterial layer on paper or a polymer film sheet, and by further forming the coating layer thereupon. To be specific, the antibacterial layer is formed on the paper or the polymer film with a thickness of 500 to 2000 μm by deposition and further, the coating layer is formed. Or, using a thin polymer film as a substrate layer, followed by forming the antibacterial layer by deposition thereupon and further followed by forming the coating layer thereby obtaining a complex, and by laminating the complex in the substrate layer side on the plastic sheet such as hard vinyl chloride resins and the like.
In order to manufacture medical charts made of the antibacterial laminate of the present invention, the antibacterial layer and the coating layer are formed on paper (including artificial paper). In this case, the antibacterial layer may be formed not only on one side but also on both sides.
[4. Food Packaging Film]
Also, since the antibacterial laminate of the present invention is film-like, it can be used as a film for packaging foods as it is. In the case of the food packaging film, it is used packaging foods so as to make the coating layer side inner side. The food packaging film can be used by taking out the amount required for use from the tabularly laminated film as in the case of a wrapping film for foods or an aluminum foil for foods.
(Production of the Antibacterial Laminate)
An adhesive agent (polyester/isocyanate) was coated with a film thickness of 0.3 μm on a biaxially stretched PET film whose thickness is 38 μm. On the film, a silver ion was deposited by an ion deposition method thereby producing a deposition film with a thickness of 800 Å to be the antibacterial layer. Next, a top coating solution (polyester (amorphous)/nitrocellulose/benzoguanamine (composition ratio: 30:30:40 wt %); resin concentration 7.3%) was coated on the antibacterial layer so as to have a thickness of 0.5 μm, and after drying, the film-like antibacterial laminate was obtained. When the coating layer of the antibacterial laminate is observed with an electronic microscope, it was acknowledged to have no pores. As a strip of Example 1, the antibacterial laminate was subject to evaluation tests for the antibacterial property as follows.
Also, as comparison, a biaxially stretched PET film with a thickness of 38 μm was used (Comparative Example 1).
(Evaluation Test for Antibacterial Capability)
[1] Test Method
[Film Contact Method]
According to JIS Z 2801, on a test piece surface, bacterial liquid adjusted by 1/500 standard bouillon was dripped, followed by contacting with a film, thereafter preserving it under the temperature of 35° C. After that, the viable cell number was measured for the bacterial liquid on the test pieces by the lapsed time (0 hour, 24 hours, 48 hours, and 72 hours) and the evaluation of the antibacterial capability was made. The result is shown in Table 1.
[2] Used Strain
(Production of Antibacterial Laminate Film)
The adhesive agent (polyester/isocyanate) with a film thickness of 0.3 μm was coated on a biaxially stretched PET film with a thickness of 12 μm. On the film, silver was deposited by a vacuum deposition method thereby preparing a deposition film whose thickness is varied, as an antibacterial layer. Next, the top coating solution (polyester (amorphous)/nitrocellulose/benzoguanamine (composition ratio: 30:30:40 wt %); resin concentration 7.3%) was coated on the antibacterial layer so as to have a thickness of 0.2 μm, and after drying, the film-like antibacterial laminate was obtained. When each coating layer of the antibacterial laminate is observed with the electronic microscope, it was acknowledged to have no pores for each layer. As strips of Examples 2 to 4, the antibacterial laminates were subject to the test for evaluating the antibacterial property as follows, respectively.
The thickness of the silver deposited film in the Examples of 2 to 4 is as follows.
Example 2: 550 Å
Example 3: 200 Å
Example 4: 10 Å
Also, as comparison, in the above mentioned operation, the laminating film with no silver deposited layer provided was manufactured (Comparative Example 2).
As in the Examples 2 to 4, an anchor coating adhesive agent (polyester/isocyanate) with a film thickness of 0.3 μm was coated on the biaxially stretched PET film with a thickness of 12 μm. On the film, silver was deposited with a thickness of 100 Å by a vacuum deposition method thereby preparing an antibacterial layer. Next, the same top coating solution as in the Examples 2 to 4, was coated on the antibacterial layer so as to have a thickness of 0.2 μm. After drying, the adhesives as mentioned above (polyester/isocyanate) were coated so as to have a film thickness of 0.85 μm, thereby obtaining the film-like antibacterial laminate after drying. When the coating layer of the antibacterial laminate is observed with the electronic microscope, it was acknowledged to have no pores. As a strip of Example 5, the antibacterial laminate was subject to evaluation tests for the antibacterial property as follows.
(Appearance)
When the appearance of each antibacterial laminate of the Examples 2 to 5 was observed visually, it was found that the antibacterial laminate of the Example 2 was opaque silver, the antibacterial laminate of the Example 3 was translucent, and the antibacterial laminates of the Examples 4 and 5 were transparent.
(Test for Antibacterial or Antifungal Property)
Each of the antibacterial laminates of Examples 2 to 5 was used as a test piece and subject to evaluation tests for the antibacterial or the antifungal property according to following methods.
[1] Test Method
[Film Contact Method]
According to JIS Z 2801, the bacterial liquid adjusted by 1/500 standard bouillon was dripped on a test piece surface, and followed by contacting with a film thereby preserving it under the temperature of 35° C. For information, the initiation cell number was 1.0×105 to 1.9×105. After that, the viable cell number was measured for the bacterial liquid on the test pieces by the lapsed time (6 hours and 24 hours) and the evaluation of the antibacterial capability of the film surface was made. The result is shown in Table 2.
[2] Used Strain
E. coli NBRC-397
St. aureus
As. niger NBRC-634
As shown in Table 2, not only against escherichia coli and staphylococcus aureus, but the antifungal property against aspergillus niger was acknowledged in Example 2 that the number of cell was reduced from initiation cell number of 100,000 to 130 in 24 hours, in Example 3 that the number of bacteria was reduced from initiation cell number of 100,000 to 4,900, and in Example 4 that the number of cell was reduced to not more than 10. Also, as in Example 5, when the adhesion layer is further provided on the whole surface of the coating layer, although the cell number was acknowledged to be reduced compared with the initiation cell number, it cannot be said that the antibacterial property is high in comparison with Examples 1 to 4.
(Evaluation test for Oxygen Barrier Property)
Regarding oxygen barrier property, measurement was made under the following condition.
Measuring apparatus: Oxtran 2/20MG, manufactured by MOCON
Measuring temperature 23° C., dried
The result is shown in Table 3.
As in Example 3, in Comparative Example 2 with no silver deposition, the numerical value of oxygen permeability exceeding the 100 ml/m2·day·atm was acknowledged. On the other hand, in Example 2 with silver deposition of 550 Å, the oxygen barrier property with the oxygen permeability of less than 1 ml/m2·day·atm was acknowledged and it was acknowledged to have the very high level of the oxygen barrier property.
Since the antibacterial laminate of the present invention has no color changes due to oxidization, sustains the antibacterial property for a long time, and has high safety, it can preferably be used for food packaging bags, food packaging sheets, medical bags such as transfusion bags, urine-collecting bags, medical charts, consultation tickets, and the like.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-138288 | May 2006 | JP | national |
| 2006-339012 | Dec 2006 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2007/060152 | 5/17/2007 | WO | 00 | 9/17/2008 |
