JPH08157750A - Antibacterial and fungiproof coating composition and formation of coating film therefrom - Google Patents

Abstract

PURPOSE: To obtain an antibacterial coating compsn. by compounding a liq. or powdery coating compsn. contg. a tetrafluoroethylene resin and a tetrafluoroethylene copolymer resin with an inorg. antibacterial agent prepd. by impregnating with specific metal ions. CONSTITUTION: An antibacterial and fungiproof coating compsn. is obtd. by mixing small amts. of a surfactant and a dispersant (e.g. an alkylarylsulfonate) into a liq. or powder coating compsn. mainly comprising a tetrafluoroethylene resin and a tetrafluoroethylene copolymer resin and then mixing the compsn. with 0.3-10wt.% (based on the solid content of the compsn.) inorg. antibacterial agent powder with a ball mill, etc. The powder is obtd. by fixing antibacterial metal ions selected from among Cu, Ag, Zn, etc., to the surface of a silica gel and has an average particle size of about 1-5μm. The obtd. compsn. is applied to the surface of a substrate (e.g. a stainless steel sheet) and baked at about 300-430 deg.C to form an antibacterial and fungiproof fluororesin coating film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to fields requiring antibacterial and antifungal properties, as well as water repellency, non-adhesiveness and slipperiness, which are characteristics of fluororesins, such as hopper storage tanks for food machinery. The present invention relates to an antibacterial / antifungal coating composition that can be widely used for toilet bowls related to sanitary equipment, kitchen appliances, and the like, and a method for forming a coating film using the same.

[0002]

2. Description of the Related Art In a high temperature and high humidity environment, bacteria and mold are liable to cause damage, and environmental pollution has become a problem in food and packaging factories. For example, the proliferation and spoilage of bacteria and mold during storage of food such as food tanks and hoppers in food factories.

On the other hand, fluororesin-coated articles are widely used in hoppers, storage tanks and the like by utilizing their non-adhesiveness, slipperiness and water repellency. In addition, attempts have been made to suppress the growth of bacteria and mold by coating an antibacterial composition obtained by mixing an antibacterial material with various general-purpose paints on a hopper, a storage tank or the like.

[0004]

However, although the above-mentioned fluororesin coating and antibacterial composition coating have the corresponding effects, the dispersion and volatilization of the antibacterial agent due to heating in the coating film forming step and the surface of the antibacterial material. Since the tension (for example, 500 to 1000 dynes / cm for inorganic materials) is higher than the surface tension of the coating material (for example, about 50 dynes / cm for epoxy resin, about 20 dynes / cm for fluororesin), the surface of the antibacterial material is changed by the paint. Since the antibacterial effect is lowered due to the fact that the film becomes easily wet, the antibacterial effect is lowered even if the film is slightly exposed. Therefore, an object of the present invention is to provide a coating composition capable of imparting non-adhesiveness, slipperiness, water repellency, heat resistance, and antibacterial and antifungal properties.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been proposed in view of the above, and it is proposed that silica gel is added to a liquid coating material and a powder coating material containing a tetrafluoroethylene resin, an ethylene tetrafluoride copolymer resin as a main component. The present invention relates to an antibacterial / antifungal coating composition comprising 0.3 to 10% of an inorganic antibacterial material impregnated with a metal ion having a bactericidal action. Alternatively, a fine powder of an inorganic antibacterial material obtained by impregnating silica gel surface with metal ions having a bactericidal action in a liquid coating or a powder coating containing a tetrafluoroethylene resin, an ethylene tetrafluoride copolymer resin as a main component. To 0.3 to 10% and further a dispersant is added to prevent the aggregation of the antibacterial material. The present invention relates to an antibacterial and antifungal coating composition. That is, by using the fine powder of the inorganic antibacterial material and the dispersant, the surface area of the antibacterial material is increased and the antibacterial effect is improved. Further, the present invention is to apply the above coating composition to the surface of the object to be treated, and then fire it to obtain antibacterial properties.
It is also proposed to form an antifungal coating.

The present inventors have made various studies on antibacterial materials having conditions (for example, heat resistance) for forming a fluororesin coating film containing a tetrafluoroethylene resin or a tetrafluoroethylene copolymer resin as a main component. did. That is, the thermal decomposition temperature of commercially available organic antibacterial materials is approximately 280 ° C. or lower, and it cannot be used at the firing temperature for forming a fluororesin coating film. Then, they have found an inorganic antibacterial material having a heat resistance of 400 ° C. or higher as described in detail below. In addition to heat resistance, this inorganic antibacterial material has the characteristics of being nontoxic and capable of maintaining long-term sustainability of antibacterial effect.

The base material of this inorganic antibacterial material is highly safe silica gel which is accepted as a food additive and is a porous substance containing silicon dioxide (SiO ₂ ) as a main component. A compound containing a metal ion having a bactericidal action is formed on the surface of the pores of this silica gel. Antibacterial, fixing of bactericidal metal ions (e.g., copper ions), alumino silicates ((formula _{xM 2 O · Al 2 O 3} · ySiO 2 · Z
H ₂ O and M are ion-exchangeable metals, x and y are metal oxide and silicon oxide coefficients, and Z is the number of water molecules). Since it is ion-exchanged with the bactericidal metal at a low temperature, it is firmly fixed in the pores of the silica gel by ionic bond and the durability is maintained. Since this inorganic antibacterial material is composed entirely of inorganic components, it has excellent heat resistance and
It does not change color even when heated to ℃, and it does not change at the melting temperature of the fluororesin or the firing temperature of the paint. Further, the antibacterial metal is sparingly soluble in water or an organic solvent, and the elution of the antibacterial metal is small, so that the antibacterial effect can be maintained for a long time. Further, since this inorganic antibacterial material is a white fine powder (particle size 1 to 5 μm) and is a uniform particle, it can be uniformly dispersed in a paint or the like and has little influence on the hue.

On the other hand, the fluororesin used in the present invention is mainly composed of tetrafluoroethylene resin or tetrafluoroethylene copolymer resin as described above. Fine particles of these fluororesins are mixed with water or water. It is possible to use an emulsion dispersed in a liquid such as an organic solvent, a suspension, or a powdered fluororesin.

The coating composition of the present invention is obtained by adding the inorganic antibacterial material powder (average particle size 1 to 5 μm) to the above fluororesin coating material.
m) is added in an amount of 0.3 to 10% with respect to the solid content in the paint. If the amount of the inorganic antibacterial material added is less than 0.3%, no antibacterial effect is observed. If it is more than 10%, the characteristics of the fluororesin are deteriorated.

The above coating composition of the present invention can be specifically manufactured by the following method. In the case of liquid paints, a small amount of surfactant (eg amphoteric surfactant) and dispersant (eg alkylallyl sulfonate, amines) are added to fluororesin paint, and the mixture is stirred and mixed with a predetermined amount of inorganic type Add and mix antibacterial material. In this case, the surfactant has an effect of improving compatibility between the fluororesin and the inorganic antibacterial material, and the dispersant is useful for preventing aggregation of the inorganic antibacterial material. In addition, as a masterbatch method, a small amount of a surfactant and a dispersant are added to a fluororesin paint, and 10 to 20 times the predetermined amount of an inorganic antibacterial material is added to the fluororesin paint, followed by stirring and mixing to form a masterbatch. It is possible to appropriately mix only the fluororesin paint in a predetermined amount taken out from the above to obtain a predetermined concentration. This method is suitable for blending a small amount of inorganic antibacterial material. It is desirable to mix the above blended materials by a method such as a ball mill roller, which does not apply much shearing force. That is, the coating material may solidify when the shearing force increases. Further, when the fluororesin coating material is powder, the above master batch method is suitable. A certain amount of 10 for powder coating
A masterbatch is prepared by uniformly mixing up to 20 times the inorganic antibacterial material powder with a mixer such as a Henschel mixer. A predetermined concentration can be obtained by appropriately adding powder coating material to a certain amount taken out from this and diluting it.

The coating composition produced by these methods is, for example, on the surface of a blast-treated steel plate as an object to be treated,
An antibacterial coating film can be obtained by applying the coating by the air spray method and forming the coating film under the heating and baking conditions of the fluororesin paint. As the coating method, not only the air spray method but also an airless spray method, an electrostatic spray method and an electrostatic powder coating method, a powder fluidized dipping method, a lot lining method, etc. can be applied, and are not particularly limited. Absent. The heating and firing conditions are not limited as long as they are above the melting point of the resin, and firing at a high temperature of 300 to 430 ° C. is performed for actual coating film formation.
It is baked at about 70 to 430 ° C.

[0012]

【Example】

[Example 1] Ethylene tetrafluoride resin coating (Teflon 85
1-224 Green, manufactured by DuPont Co., Ltd.) 250 g was sampled in a polyethylene container, and a small amount of a surfactant (amphoteric surfactant) and a dispersant (alkyl sulfonate) were added thereto and mixed, and then an inorganic type. 2.5% of the antibacterial material powder (antibacterial powder in which antibacterial metal [silver, copper, zinc] ions are immobilized on the surface of silica gel, average particle size 3 μm, hereinafter referred to as inorganic antibacterial material A) is 2.5% ( 2.8g)
Was added. Using a ball mill roller, add about 30
The mixture was mixed for a minute to obtain an antibacterial coating composition. The obtained paint is a stainless steel plate (50 mm x 40 mm x 1 mm thick)
After painting on the surface of the, heat baking at about 400 ℃, about 30
A fluororesin-coated article having a film thickness of -40 μm was prepared.

[Example 2] 100 g of the fluororesin paint used in Example 1 was sampled in a polyethylene container, and a small amount of a surfactant (amphoteric surfactant) and a dispersant (alkyl sulfonate) were added thereto. After adding and mixing, inorganic antibacterial material powder (antibacterial powder in which antibacterial metal [silver, copper, zinc] ions are immobilized on the surface of silica gel, average particle size 1 μm,
Hereinafter, 28 g of an inorganic antibacterial material B) was added and mixed by a ball mill roller for about 30 minutes to obtain a high-concentration masterbatch paint. 10 g of the masterbatch paint prepared above and fluororesin paint (Teflon 851-224 Green, manufactured by DuPont Co., Ltd.) in another polyethylene container.
240 g was put and mixed by a ball mill roller for about 30 minutes to obtain a coating composition (antibacterial powder concentration ... 2.5% with respect to coating solid content). Using the obtained coating composition, coating was performed under the same conditions as in Example 1 to prepare a fluororesin-coated article.

[Example 3] To the same fluororesin paint as in Example 1 above, 3.5% of the inorganic antibacterial material A was mixed in the same manner as in Example 1 with respect to the solid content of the paint. A composition was obtained. The obtained coating composition was applied under the same conditions as in Example 1 to prepare a fluororesin-coated product.

[Example 4] A fluororesin-coated product was prepared under exactly the same conditions as in Example 3 except that 5.0% of the inorganic antibacterial material A was added to the coating solid content.

[Example 5] 14 g of the masterbatch coating prepared in Example 2 (containing 3.9 g of inorganic antibacterial material B)
And fluororesin paint (Teflon 851-224 green,
240 g of DuPont Co., Ltd.) was placed in a polyethylene container and mixed by a ball mill roller for about 30 minutes to obtain a coating composition (concentration of inorganic antibacterial material B ...
5%). The coating composition was applied under the same conditions as in Example 1 to prepare a fluororesin-coated product.

[Example 6] 20 g of the masterbatch paint prepared in Example 2 (containing 5.6 g of inorganic antibacterial material B)
And fluororesin paint (Teflon 851-224 green,
240 g of DuPont Co., Ltd.) was placed in a polyethylene container and mixed by a ball mill roller for about 30 minutes, and the coating composition (inorganic antibacterial material B concentration ...
0%). The coating composition was applied under the same conditions as in Example 1 to prepare a fluororesin-coated product.

[Comparative Example] Ethylene tetrafluoride resin coating (Teflon 851-224 Green, manufactured by DuPont)
Is applied to the surface of a stainless steel plate (50 mm x 40 mm x 1 mm thick) and heated and baked at about 400 ° C, then about 30 ~
A fluororesin-coated article having a film thickness of 40 μm was prepared.

<Antibacterial Test> An antibacterial test was carried out by the following method using the fluororesin-coated articles prepared in Examples 1 to 6 and Comparative Example. (Test 1) On the coating film surfaces of the fluororesin-coated articles of Examples 1 and 2 and Comparative Example, a fungal suspension of Salmonella (initial number of bacteria: 7.
(2 × 10 ⁵ cells / ml) was added dropwise, and the mixture was allowed to stand at 25 ° C. for 3 hours, then the bacteria adhering to the coating film surface were washed, and the number of bacteria was measured. The results are shown in Table 1. (Test 2) A suspension of fungi of Aspergillus niger was dropped onto the coating film surfaces of the fluororesin-coated articles of Examples 3 to 6 and Comparative Example (initial bacterial cell number: 3.6 × 10 ⁵ cells / 50 mm × 40 mm), and 25 ℃
The number of bacteria on the surface of the coating film after standing for 48 hours was measured. The results are shown in Table 1.

[0020]

[Table 1]

The test results will be described based on Table 1 above.
In Examples 1 and 2 and Comparative Example-1, Salmonella as a test bacterial species was cultured on the surface of the coating film, and the number of bacteria on the coating film surface was measured after 3 hours. As a result, in the samples of Examples 1 and 2 to which the inorganic antibacterial material was added, the bacteria were dead after 3 hours, and the effect of the inorganic antibacterial material was remarkably exhibited. On the other hand, in the case where the inorganic antibacterial material is not added as in Comparative Example-1, the bacterial survival rate is 93%. In Examples 3 to 6 and Comparative Example-2, black mold fungi were cultured on the coating film surface as the test bacterial species, and the number of bacteria after 48 hours was measured. As a result, in Examples 3 to 6 in which the inorganic antibacterial material is added, the survival rate of the bacterium is 2 to 3%, whereas in Comparative Examples-2, the inorganic antibacterial material is not added. Bacterial survival rate is 8.3%
It has become. Therefore, the effect of imparting antibacterial properties by the coating composition of the present invention was confirmed.

<Change in Characteristics of Fluorine Resin Coating Film According to Addition Amount of Inorganic Antibacterial Material> Changes in coating film physical properties were investigated by changing the content of the inorganic antibacterial material in the coating composition. Fluororesin paint (Teflon 851-224 Green, manufactured by DuPont)
0.3% of the inorganic antibacterial materials A and B with respect to the coating solid content of
Different coating compositions were prepared within the range of -10%, and a fluororesin-coated article was prepared under exactly the same conditions as in Example 1 above. The static friction coefficient and water repellency were measured and observed as the coating film physical properties of the fluororesin coating film. The results are shown in Table 2.

[0023]

[Table 2]

From Table 2 above, the static friction coefficient of the coating film increases as the amount of the inorganic antibacterial material added increases. Also,
Water repellency also tended to decrease slightly as the amount of inorganic antibacterial material added increased. Therefore, the addition amount of the inorganic antibacterial material for maintaining the static friction coefficient and the water repellency, which are one of the characteristics of the fluororesin, is limited to the range of 10% or less. However, even if the inorganic antibacterial material is added by 10%, the coefficient of static friction is smaller than that when other resins are used.

[0025]

As is clear from the above description, the coating composition of the present invention has antibacterial and antifungal properties as well as water repellency, non-adhesiveness, low friction, heat resistance, etc. It is possible to provide an excellent coating film. Therefore, for example, hoppers, containers, screens, steel plate belts, food molds, food cans, batter rolls, etc. for food products, kitchen sets for kitchen products, rice cookers, toilet seats for toilet products,
It can be applied to a wide variety of applications such as toilet bowls, medical equipment parts, bed parts, medical equipment in hospitals, interior parts, seats, air-conditioning parts in automobiles, and places where fungi and molds are generated. Further, the method for forming a coating film of the present invention is to perform a usual fluororesin coating operation and treatment using the coating composition, and since it does not use particularly complicated treatment or special equipment, it is extremely It has high practical value.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location C09D 127/18 PFH

Claims (3)

[Claims] 1. An inorganic antibacterial material obtained by impregnating a surface of silica gel with a metal ion having a bactericidal action in a liquid coating material and a powder coating material containing a tetrafluoroethylene resin, an ethylene tetrafluoride copolymer resin as a main component. An antibacterial and antifungal coating composition characterized by being added in an amount of 0.3 to 10%. 2. An inorganic antibacterial material finely-divided into a liquid coating material and a powder coating material containing a tetrafluoroethylene resin, an ethylene tetrafluoride copolymer resin as a main component, and a surface of silica gel impregnated with a metal ion having a bactericidal action. An antibacterial and antifungal coating composition, characterized in that 0.3 to 10% of powder is added and a dispersant is further added. 3. A metal ion having a bactericidal action on the surface of silica gel is added to the surface of the object to be treated in a liquid coating material and a powder coating material containing an ethylene tetrafluoride resin or an ethylene tetrafluoride copolymer resin as a main component. 0.3-10% of impregnated inorganic antibacterial material
A method for forming an antibacterial and antifungal coating film, which comprises firing after coating the coating composition obtained by adding.