JPH11181109A - Antibacterial film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare an antibacterial film having surface scratch resistance, excellent appearance, and sustained antibacterial effect by mixing a synthetic resin with a particulate antibacterial agent such as a metal-carrying zeolite and a spherical antiblocking agent having a particle diameter larger than that of the antibacterial. SOLUTION: The synthetic resin used is exemplified by a polyolefin, a polyester, a nylon, or a polyvinyl chloride. The antibacterial agent used is the one prepared by impregnating a natural or synthetic zeolite comprising an aluminosilicate, a polyphosphate, or the like with a simple metal such as silver, copper, zinc or tin, or a compound thereof and is particularly desirably the one prepared by dissolving a soluble salt of such a metal in water and subjecting the solution and a carrier to ion exchange to effect firm adsorption of the metal on the carrier. It is desirable that the antibacterial agent has a particle diameter of, generally, 0.05-10 μm and is added in an amount of 0.05-10-wt.% to the film. The antiblocking agent used is a spherical inorganic oxide or an organic polymer and is desirably used in an amount of 0.05-10 wt.%. The antiblocking agent added improves the scratch resistance of the surface of the film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film having antibacterial properties. More specifically, it is a synthetic resin film in which the surface of the antibacterial film is easily damaged (hereinafter referred to as scratching property).

[0002]

2. Description of the Related Art Hitherto, films made of synthetic resins such as polyolefins containing an antibacterial agent have been known. However, the antibacterial film has a drawback that it lacks long-term stability due to the dropout of the antibacterial agent, has poor scratch resistance, and easily scratches the surface.

[0003]

In pursuit of the reason, generally, as an antibacterial agent, a metal having an antibacterial action on a solid substance having an adsorption ability such as zeolite, for example, silver,
Copper, zinc, a metal such as tin or a compound thereof is supported by physical adsorption or ion exchange, etc., and those granular antibacterial agents are exposed on the film surface,
Although the antibacterial agent that has been exposed works effectively, the film comes into contact with other substances and is rubbed. As a result, it was found that the projections of the antibacterial agent mutually scratched the surface.

Accordingly, the present invention provides an antibacterial effect,
Moreover, it is an object to provide a film having excellent appearance over a long period of time.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above-mentioned object, and as a result, while allowing a particulate antibacterial agent such as zeolite carrying a metal to be present on the film surface, and The inventors succeeded in solving the problem of improving the scratch resistance of the film surface, and have proposed the present invention.

That is, the present invention is an antibacterial film comprising a synthetic resin, a particulate antibacterial agent and a spherical antiblocking agent, wherein the average particle size of the spherical antiblocking agent is larger than the average particle size of the antibacterial agent.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The synthetic resin used in the antibacterial film of the present invention has a sufficient dispersibility of an antibacterial agent and an antiblocking agent and can be formed into a film.
It can be arbitrarily selected. For example, polyethylene, polypropylene, a copolymer of propylene and α-olefin and a mixture thereof, polyester, nylon, polyvinyl chloride and the like can be mentioned. However, polyolefin homo- or copolymers are most effective. Particularly preferred polyolefins include homopolypropylene, ethylene or butene-1 content of 10% by weight.
The following propylene copolymer is shown.

As the antibacterial agent used in the present invention, a known antibacterial agent obtained by physically or chemically adsorbing a metal or a metal compound on an inorganic compound carrier can be used without any limitation. Commonly used carriers are natural or synthetic zeolites composed of aluminosilicates, phosphates, silicates, alumina, silica, activated clay, activated carbon, and the like. Among them, substances having ion exchange ability, for example, zeolites, polyphosphoric acid Salts and the like are preferred.

The metal to be supported is used as a simple metal or a compound such as silver, copper, zinc, and tin. In particular, a soluble salt that can be dissolved in water or the like is preferable because it is strongly adsorbed to a carrier by an ion exchange reaction and also has a sufficient bactericidal activity. The amount of adsorption of these metals on the carrier is
Although not particularly limited, the metal content may be 0.01% by weight or more, preferably 1% by weight or more. Normally,
About 0.05 to 10% by weight is used.

[0010] Further, since the antibacterial agent is blended into the film, the smaller the particle size, the better.
〜１０10 μm. Usually, an antibacterial agent having an average particle size of 以下 or less, preferably １ ／ or less of the thickness of the target film is used.

The amount of the antibacterial agent used in the present invention in the film is preferably from 0.05 to 10% by weight, more preferably from 0.1 to 5% by weight. The amount is 0.0
If the amount is less than 5% by weight, sufficient antibacterial effect is not exhibited. If the amount exceeds 10% by weight, the effect is saturated, the cost is increased, and the appearance of the film is deteriorated.

The anti-blocking agent used in the present invention is a spherical inorganic oxide or an organic polymer. Here, the term “spherical” means not only a true sphere but also an almond shape, which is a general term for a shape having no so-called sharp projecting portions. Of course, a shape closer to a true sphere is preferable. The types of the inorganic oxide and the organic polymer are not particularly limited, but are generally easily available, have good dispersion in a synthetic resin,
In addition, it is preferable to select a material having a value close to the refractive index because the transparency of the film can be maintained. For polyolefin films, such inorganic oxides, silica,
It is preferable to use a composite oxide containing silica as a main component, for example, 50 mol% or more, such as silica-alumina, silica-zirconia, and silica-titania. As the organic polymer, silicone resin particles, silicone rubber particles, polyamide particles, condensation type resin particles having a tridiane ring, crosslinked polystyrene particles, crosslinked polymethyl acrylate particles,
Crosslinked polymethyl methacrylate particles can be suitably used.

The addition amount of the spherical antiblocking agent used in the present invention is preferably 0.05 to 10% by weight, more preferably 0.1 to 5% by weight. If the amount is less than 0.05% by weight, the scratch resistance is not improved. If the amount exceeds 10% by weight, the effect is saturated and the cost is increased, and the appearance of the film is unfavorably deteriorated.

The most important feature of the present invention resides in the relationship between the particle size of the antibacterial agent and the particle size of the antiblocking agent incorporated in the synthetic resin. That is, it is essential that the antiblocking agent has a larger average particle diameter than the antibacterial agent. Accordingly, the particle size of the anti-blocking agent is selected depending on the particle size of the antibacterial agent to be added at the same time.
An antiblocking agent having an average particle size of 5 times or more, preferably 1.5 times or more is used. If the average particle size of the spherical anti-blocking agent is the same as or smaller than the average particle size of the antibacterial agent, the scratch resistance of the film surface is not improved and the effects of the present invention cannot be obtained.

The method of forming (forming a film) of the antibacterial film of the present invention is not particularly limited. For example, the film can be formed by a casting method, an extrusion method (such as an inflation method, a T-die method, or a calendar method). it can.

[0016]

As described above, the antibacterial film of the present invention can improve the antibacterial property and the antifungal property by increasing the average particle size of the spherical antiblocking agent to be larger than the average particle size of the antibacterial agent. It has excellent properties that have not been realized conventionally, such as being excellent and capable of preventing scratches on the film surface, being excellent in film appearance for a long period of time, and capable of maintaining antibacterial efficacy. The present invention, by increasing the average particle size of the spherical anti-blocking agent, than the average particle size of the antimicrobial agent, from the projections of the antimicrobial agent on the film surface, by increasing the projections of the spherical anti-blocking agent, If you rub against a comrade or other substance,
The anti-bacterial agent does not rub against the spherical anti-blocking agent with high protrusions, so it is possible to prevent the film surface from being scratched, and the film appearance is excellent for a long time, and the antibacterial effect can be maintained. Things.

[0017]

EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

The antibacterial agents and spherical antiblocking agents used in Examples and Comparative Examples are shown in Table 1.

[0019]

[Table 1]

The measurement method used in the examples and comparative examples was carried out by the following method.

(1) Antibacterial property The film was cut into 5 cm square, placed horizontally in a petri dish, and 0.5 cc of a solution containing E. coli was dropped on the film. It was stored at 35 ° C., and after a certain period of time, the bacteria on the film were washed, and the solution was mixed with an agar medium to grow the bacteria. The number of colonies formed was counted, and the antibacterial property was evaluated.

(2) Scratch resistance (scratch haze) In order to evaluate the easiness of scratching when the films are rubbed, two films were prepared and one of the films (20 ×
30 cm) was fixed as the lower film. The other film is used as the upper film, and the diameter of the upper film is 10 cm.
The lower film was brought into contact with a load of 4.6 kg on the area of the circle of, and the upper film was horizontally rubbed five times back and forth for 20 cm. The haze value before and after performing the above operation was measured, and it was evaluated that the smaller the haze value, the less likely it was to be damaged. The criteria are as follows.

The haze value was measured according to JIS K6714.

[0024]

(3) Average particle size 50% in volume integrated distribution by laser diffraction scattering method
Refers to the diameter.

Example 1 A polypropylene homopolymer having a melt index of 1.8 was extruded into a sheet at a resin temperature of 260 ° C. by a T-die extruder, and cooled and solidified by a chill roll maintained at 40 ° C. to obtain a polypropylene having a thickness of 900 μm. I got a sheet. Next, this sheet is heated to 100 to 150 by a hot roll stretching machine.
The film was stretched at 4.5 ° C. by 4.5 times to obtain a 200 μm uniaxially stretched sheet. Next, as a particulate antibacterial agent, an antibacterial zeolite having an average particle size of 1.0 μm and carrying silver was contained at 1.0% by weight, and as a spherical antiblocking agent, 0.3% by weight of silica having an average particle size of 1.5 μm was contained. A polypropylene homopolymer having a melt index of 8.0 was extruded into a sheet at a resin temperature of 230 ° C. using a T-die extruder, and bonded to the uniaxially stretched sheet to obtain a 210 μm two-layer sheet. This two-layer sheet was stretched 10 times with a transverse stretching machine.

The scratch resistance and antibacterial property of the obtained film were measured, and the results are shown in Table 2. Example 2 A film formation evaluation was performed in exactly the same manner as in Example 1 except that the addition amount of the particulate antibacterial agent of Example 1 was changed to 0.5% by weight. Table 3 shows the results.

Example 3 The spherical anti-blocking agent of Example 1 was used with an average particle size of 1.8.
Except that the crosslinked polymethyl methacrylate of μm was used, the film formation was evaluated in exactly the same manner as in Example 1. Table 3 shows the results.

Example 4 Example 1 was repeated except that the average particle size of the granular antibacterial agent of Example 1 was changed to 3.0 μm, and the spherical antiblocking agent was changed to 0.1% by weight of silica having an average particle size of 5.0 μm. The film formation was evaluated in exactly the same manner as in the above. Table 3 shows the results.

Example 5 A polypropylene homopolymer having a melt index of 8.0 was used for the outer layer as a particulate antibacterial agent for the inner layer, and the average particle size was 1.0 μm.
m, 1.0% by weight of antibacterial zeolite carrying silver and 1.5 μm
Extruded at a resin temperature of 230 ° C by a two-layer, two-layer coextrusion method using a polypropylene homopolymer having a melt index of 8.0 containing 0.3% by weight of silica (silicon dioxide).
After being solidified by a cooling roll, a film having a thickness of 30 μm was obtained. The layer structure of the obtained film is as follows: outer layer 28 μm, inner layer 2 μm
Met. Table 3 shows the results.

Comparative Example 1 A film was formed and evaluated exactly in the same manner as in Example 1 except that the granular antibacterial agent of Example 1 was not added. Table 3 shows the results.

Comparative Example 2 A film was formed and evaluated exactly in the same manner as in Example 1 except that the spherical antiblocking agent of Example 1 was not added. Table 3 shows the results.

Comparative Example 3 The spherical anti-blocking agent of Example 1 was used with an average particle size of 1.0
The film formation was evaluated in exactly the same manner as in Example 1 except that the silica was changed to μm. Table 3 shows the results.

Comparative Example 4 The spherical anti-blocking agent of Example 1 was used with an average particle size of 0.7
0.05% by weight of μm crosslinked polymethyl methacrylate
The film formation was evaluated in exactly the same manner as in Example 1, except that Table 3 shows the results.

Comparative Example 5 The amount of the particulate antibacterial agent of Example 1 was 0.03% by weight.
Except that the spherical antiblocking agent was changed to 0.03% by weight of silica having an average particle size of 1.0 μm, film formation evaluation was performed in the same manner as in Example 1. Table 3 shows the results.

Comparative Example 6 A film was formed and evaluated exactly in the same manner as in Example 1 except that zeolite not supporting a metal was added to the granular antibacterial agent of Example 1. Table 3 shows the results.

[0037]

[Table 3]

Claims (4)

[Claims] 1. An antibacterial film comprising a synthetic resin, a particulate antibacterial agent and a spherical antiblocking agent, wherein the average particle size of the spherical antiblocking agent is larger than the average particle size of the antibacterial agent. 2. The antibacterial film according to claim 1, wherein the particulate antibacterial agent is zeolite supporting a metal. 3. The antibacterial film according to claim 1, wherein the spherical antiblocking agent is an inorganic oxide or an organic polymer. 4. The antibacterial film according to claim 1, wherein the amounts of the particulate antibacterial agent and the spherical antiblocking agent are each 0.05 to 10% by weight.