JP2006104272A - Resin product exhibiting antibacterial action - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin product such as a container or a package which exerts antibacterial actions on contents inside thereof and easily manufactured at a lower cost. <P>SOLUTION: The resin product has a substance having antibacterial actions fixed on the surface thereof (at least on the surface brought into contact with the contents). The resin product exhibiting antibacterial actions comprises a resin substrate composed of, for example, any one of polyethylene terephthalate, polyethylene, polypropylene, polycarbonate and polyvinyl chloride having silver colloid particles adsorbed on the surface thereof. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a resin product that becomes a container for pharmaceuticals, cosmetics, soft drinks, foods and the like. Specifically, the present invention relates to a resin product having an antibacterial action that prevents bacteria from growing in the contents.

  Resin materials such as polyethylene terephthalate, polyethylene, and polypropylene are strong and lightweight, and are therefore widely used as materials for containers or packaging of pharmaceuticals, cosmetics, soft drinks, foods, and the like.

  By the way, in recent consumer's desire for cleanliness, a container made of these resin materials with antibacterial properties is required. For example, PET bottles made from polyethylene terephthalate are widely used recently as containers for beverages such as soft drinks and tea. Many PET bottles have caps that can be opened and closed after opening, and can be closed when needed (when you are thirsty).

  When the cap is closed after opening the cap of the plastic bottle and drinking the beverage inside, there is a risk that bacteria may enter the bottle from the mouth of a person. The bacteria are expected to grow in the beverage depending on the environment such as temperature. In particular, when the beverage inside is exposed to a drinking state for a relatively long time, it is predicted that the corresponding bacteria are growing. Although this bacterial growth is not considered to impair hygiene to a significant extent that affects health, many consumers who seek cleanliness are concerned about this.

In response to such demands, for example, those described in Patent Documents 1 and 2 below have been proposed as resin products having an antibacterial action. In these prior arts, a plastic bottle is formed by mixing a constituent material with an antibacterial agent containing silver as an antibacterial agent.
JP-A-9-118373 JP 2003-165522 A

  Since silver is conventionally known as an antibacterial metal, resin products mixed with the above antibacterial agents are thought to have the effect of suppressing the growth of bacteria exposed on the surface, and are useful in that respect. It is a thing. However, mixing antibacterial agents with the entire materials that make up the container, etc. in order to impart antibacterial properties to the container contents is effective only for the surface antibacterial agents, and the amount of antibacterial agents is extremely large, which hinders cost. There is.

  The present invention has been made under the background as described above, and provides a resin product such as a container or a package that can exert an antibacterial action on the contents of the container, and can be easily manufactured at a lower cost. For the purpose.

  The present inventors have conducted intensive studies to solve the above-mentioned problems, and in order to exert an antibacterial effect on the contents inside the resin product, the surface of the resin product (at least the surface in contact with the content) has an antibacterial effect. We thought that it would be sufficient to fix the substances we had. Then, the inventors came up with the idea of adsorbing silver colloidal particles as an antibacterial agent that can be effectively and efficiently fixed on the surface of a resin product.

  That is, the present invention is a resin product having an antibacterial action formed by adsorbing silver colloidal particles on the surface of a resin substrate made of polyethylene terephthalate, polyethylene, polypropylene, polycarbonate, vinyl chloride, polyamide, cellulose acetate or the like.

  When fixing silver to the resin base material surface, it is difficult to uniformly coat silver by a general film forming method such as a vapor deposition method. In addition, for example, when a general silver powder dispersed in a solvent is applied to a resin substrate, the silver powder having a small particle diameter is easily adsorbed in the solvent, and uniform application becomes difficult. Further, when the particle size of the silver powder is increased, the silver powder tends to be precipitated with a solvent, and in this case, it is difficult to form a uniform coating.

  The colloidal particles applied in the present invention are fine particles such as metals and ceramics having a diameter of several to several hundreds of nanometers suspended in a medium. In colloidal particles, a compound called a protective agent is usually adsorbed to the fine particles, and the fine particle size is maintained without adsorbing the fine particles in the medium by the action of the protective agent. Uniformly suspended. Therefore, fine silver particles can be uniformly adsorbed on the surface of the resin substrate by applying the silver colloid solution to the resin substrate or immersing the resin substrate in the silver colloid solution. The operation of adsorbing the silver colloidal particles is a relatively simple operation and does not complicate the bottle manufacturing process.

  Further, in the resin product according to the present invention, silver colloidal particles are adsorbed only on the surface thereof, and the actual amount of silver used is small. Therefore, the increase in the manufacturing cost can be minimized.

  Furthermore, the colloidal silver particles have good adhesion to the resin base material due to the action of the protective agent, and are difficult to elute even after being filled with beverages or medicines in the resin product after adsorption, and have an antibacterial effect over a long period of time. Can last. Further, according to the study by the present inventors, the antibacterial action by the silver colloidal particles is uniformly applied to the contents of the resin product, and the antibacterial action extends not only to the surface in contact with the resin product surface but also to the inside. Therefore, the present invention is suitable for a resin product that contains a solid or highly viscous product having a low fluidity in addition to a beverage product having a high fluidity.

  Here, the silver colloid particles to be adsorbed will be described. First, the particle diameter of silver in the colloidal particles is preferably several nm to several hundred nm, more preferably 20 nm or less, and still more preferably 10 nm or less. . This is because the surface area can be secured by making the particle size small, and the antibacterial action can be exhibited more effectively.

  The colloidal particles usually contain a protective agent, but preferred protective agents in the present invention are polyvinylpyrrolidone, polyacrylic acid, polyethyleneimine, carboxymethylcellulose, sodium citrate, sodium oxalate, glucose, oligosaccharide, Cyclic oligosaccharide, oligoglucosamine, chitosan, thickening polysaccharide (carrageenan, xanthan gum, guar gum, roast bean gum, tara gum, gum arabic), agar, gelatin starch, sodium alginate. Among them, the adsorptivity of polyvinylpyrrolidone is excellent and preferable. This is because the silver colloidal particles containing these protective agents are particularly excellent in affinity with the resin base material and exhibit antibacterial action without desorption after adsorption. In addition, these protective agents do not adversely affect the human body and do not harm health even when contacted with drinking water or the like.

The adsorption amount of the silver colloidal particles is preferably 0.1 mg / m ^{2 to 1} g / m ^{2 in} terms of silver weight with respect to the surface area of the resin base material to be applied. This is because if it is less than 0.1 mg / m ² , sufficient antibacterial action cannot be exerted, and if it exceeds 1 g / m ² , there is no significant difference in action, and only increases costs. In addition, you may change this adsorption amount with the kind of content of the resin product. For example, for a container with no nutrients such as mineral water, 0.3 mg / m ² (9 μg for a 500 mL PET bottle (with an internal surface area of about 300 cm ² )) is sufficient. In the case of a container or the like, it is preferably 170 mg / m ² (5 mg for a 500 mL PET bottle) or more. The adsorption amount per unit area of silver was measured by ICP emission spectroscopic analysis.

  In the present invention, the form of the resin base material on which the silver colloid particles are adsorbed is not particularly limited, and can be applied to bottle-shaped, sheet-shaped, bag-shaped, container-shaped, and tube-shaped resins. In addition, this shape may be combined with paper, metal foil, or the like on the outside of the resin. And thereby, it can be set as containers, tubes, such as a bottle, a sheet | seat (wrap), a cup, a tray, and a bowl which have an antimicrobial effect. Moreover, the silver colloidal particle should just be adsorb | sucked by the surface which contact | connects the substance which has an antimicrobial effect. Therefore, for example, in a bottle, silver colloid particles may be adsorbed on the inner surface of the bottle in contact with the contents, and the sheet may be adsorbed only on one side.

  As a method for adsorbing silver colloidal particles on a resin base material, either a method of immersing a resin base material in a silver colloid solution or a method of applying a silver colloid solution to a resin base material can be applied. Moreover, when apply | coating a silver colloid solution, various methods, such as a spray method and a printing method, are applicable.

  As a method for producing a silver colloid solution, a reduction method that has been conventionally known as a method for producing a colloid solution is preferably used. In the reduction method, the metal salt of the metal constituting the fine particles is dissolved in a solvent and ionized, and a protective agent and, if necessary, a reducing agent are added to reduce the metal ions to form fine particles. It protects the fine particles produced by the agent. The protective agent may be dissolved simultaneously with the metal salt. In order to disperse fine particles composed of a plurality of metals, it is possible to dissolve a plurality of metal salts in a solvent.

  As a metal salt used as a raw material, silver chlorate, silver nitrate, silver acetate, and organic acid silver such as silver lactate can be applied. Moreover, a protective agent can be manufactured with the well-known manufacturing method according to the said compound, and a commercially available thing may be applied. Further, the reducing agent is not particularly limited as long as it can be applied to the chemical reduction method, and any reducing agent may be used as long as it can reduce the mixed solution of the metal salt and the protective agent. Preferred reducing agents are alcohols such as ethanol, formic acid, hydrogen, hydrazine, amines, sodium borohydride, and dimethylamine borane. Some protective agents have a reducing action, and in this case, it is not necessary to add a reducing agent.

  And the density | concentration of the silver colloid solution made to adsorb | suck is preferable to set it as 0.1-1000 ppm by silver concentration, when apply | coating, such as a spray method. Moreover, when making it adsorb | suck by an immersion method, it is preferable to use a silver colloid solution with a density | concentration of 10-10000 ppm.

  The silver colloid particles can be adsorbed by producing a silver colloid solution in a resin substrate to be adsorbed and allowing it to stand, in addition to a production method of applying a colloidal silver solution produced in advance. In this case, after putting a solvent such as water into the resin product, a silver colloid solution can be produced by adding a silver compound, a protective agent and, if necessary, a reducing agent. Adsorb to the inner surface of the product.

  As described above, according to the present invention, various resin products having an antibacterial action can be easily provided at a relatively low cost.

  Hereinafter, preferred embodiments of the present invention will be described together with comparative examples. In this embodiment, silver colloid particles were adsorbed to a polyethylene terephthalate bottle (pet bottle) to give an antibacterial action.

Production of silver colloid : 0.16 g of silver nitrate was dissolved in 90 mL of pure water, 1.6 g of polyvinylpyrrolidone (hereinafter referred to as PVP) was added as a protective agent, and 10 g of ethanol was further added dropwise as a reducing agent. The mixture was stirred at 90 ° C. for 1 hour for sufficient reaction. Thereafter, this solution was poured into 500 mL of acetone, the precipitated silver colloid particles were collected, acetone was distilled off, and the silver concentration was adjusted with pure water to obtain a silver colloid solution (silver concentration 2%).

Adsorption of silver colloidal particles :
[Example 1] The silver colloid solution was diluted with ethanol to a silver concentration of 0.1%, and this was applied to a 330 mL PET bottle by a spray method to adsorb silver colloid particles on the inner surface of the bottle. Thereafter, it was washed with sterilized purified water. The inner surface of the bottle after washing was colorless and transparent, and the presence of silver colloid particles could not be confirmed with the naked eye. The amount of silver adsorbed was 270 mg / m ² .

The antibacterial action was confirmed about the PET bottle which adsorb | sucked the silver colloid particle in the above process. Sterilized purified water (330 mL) was added to the above-mentioned PET bottle, and 100 μL of a diluted solution (10 ⁻⁶ ) of S. aureus (JCM No. 2151) was added and left at 32 ° C. for 24 hours. Thereafter, the total amount of water in the bottle was filtered through a sterilized membrane filter (0.45 μ), and the number of colonies after culturing at 32 ° C. for 5 days was counted. The above test was performed on three bottles. As a result, the count number was 0 CFU in any bottle, and no bacteria were detected.

  A similar test was performed on the same kind of PET bottles on which silver colloid particles were not adsorbed, and the count after culture was 4 to 10 CFU. Therefore, the antibacterial property of the PET bottle manufactured in this embodiment was confirmed.

  Next, the affinity of the silver colloid particles to the resin was confirmed in the PET bottle manufactured in the present embodiment. In this examination, as a comparative example, a silver nitrate solution (silver concentration 0.1%, ethanol 80% solution) was sprayed on the same kind of PET bottle and then washed.

  And two PET bottles of this embodiment and a comparative example were prepared, and about each bottle, after putting 50 mL pure water and stirring, water was extracted and the silver concentration in water was measured. This operation was performed twice and the silver concentration of each time was measured. Table 1 shows the results.

  As can be seen from the above results, elution of 1 ppm or more of silver was confirmed in the PET bottle of the comparative example, and the same amount of elution occurred when water was added for the second time. On the other hand, in the bottle according to this embodiment, the silver elution amount is extremely small and the second elution amount is reduced. From this, it was confirmed that the PET bottle according to the present embodiment is excellent in the adhesion of the silver colloid particles that are antibacterial agents.

[Example 2] Instead of PET bottles, the same procedure as in Example 1 was carried out except that the colloidal silver solution was spray-dried onto 20 μm thick polyethylene and then heat-sealed to change the bag of the present invention. The number of colonies after culturing for 5 days was counted. The above test was performed on three bags. As a result, in any bag, the count was 0 CFU, and no bacteria were detected. The amount of silver adsorbed was 180 mg / m ² .

Claims (5)

A resin product with antibacterial action, formed by adsorbing silver colloidal particles on the surface of a resin substrate. The resin product according to claim 1, wherein the resin is made of any of polyethylene terephthalate, polyethylene, polypropylene, polycarbonate, and vinyl chloride. The resin product according to claim 1 or ² , wherein the adsorption amount of the silver colloidal particles is 0.1 mg / m2 to ¹ g / m2 with respect to the surface of the resin substrate. The colloidal silver particles are composed of silver particles and a protective agent for protecting the silver particles. The protective agent is polyvinylpyrrolidone, polyacrylic acid, polyethyleneimine, carboxymethylcellulose, sodium citrate, sodium oxalate, glucose, oligosaccharide, The resin product according to any one of claims 1 to 3, which is at least one of cyclic oligosaccharide, oligoglucosamine, chitosan, thickening polysaccharide, agar, gelatin starch and sodium alginate. The resin product according to any one of claims 1 to 3, wherein the resin substrate shape is a bottle shape, a sheet shape, a bag shape, a container shape, or a tube shape resin.