KR20060097222A - Antibio-composition for coating foodbowl - Google Patents

Abstract

The present invention relates to an antimicrobial coating composition for food containers, comprising a monomer mixture selected from the group consisting of carboxylic acids containing styrene and ethylenically unsaturated groups and derivatives thereof in an aqueous phase containing an emulsifier and a polymerization initiator in an aqueous phase containing 60 After emulsion polymerization at a temperature of ~ 85 ℃, prepared by adding 1 to 1000ppm silver nano solution, the copolymer obtained as a result of the emulsion polymerization reaction to the antimicrobial coating composition for food containers having a glass transition temperature of 30 ~ 80 ℃ It is about.

According to the present invention, by reducing the cost by applying a coating composition containing an expensive silver having excellent antibacterial and deodorizing effect in the form of nano silver to food containers such as disposable food containers, lunch boxes, etc. By preventing breeding, there is an effect that can prevent the contamination of bacteria during food storage.

Antibacterial, Colloid, Lunch Box, Food, Coating, Nano Silver

Description

Antimicrobial coating composition for food containers {Antibio-composition for coating foodbowl}

1 is a flow chart schematically showing a method for producing an antimicrobial coating composition for a food container according to an embodiment of the present invention.

The present invention relates to an antimicrobial coating composition for food containers, and more particularly to nano-sized silver particles (hereinafter referred to as nano silver), which can be used to cost-effectively apply expensive silver having an antibacterial effect to food containers. It relates to an antimicrobial coating composition for a food container comprising.

As the standard of living improves, interest in the environment and health increases, while the surroundings are contaminated day by day due to the flooding of various chemicals. Various harmful substances and germs are contaminating food, clothing, and houses, so removing these substances is an important industrial field today.

On the other hand, food packaging is also developing for a variety of uses, the coating material for food containers used here has also been developed a new physical properties, a material exhibiting a new function.

Korean Patent Publication No. 97-9884 describes an antimicrobial composition comprising a compound in the form of a quaternary ammonium compound, boric acid, citric acid and malic acid, which can be applied to a paper surface for food packaging containers. 2001-58565 describes a food container that can be recycled and harmless to humans by coating a polyacrylate copolymer on existing packaging paper.

On the other hand, silver has long been known as a metal that is beneficial to mankind, and has been used as silver cutlery, silver chopsticks, silverware and silver for removing bad breath. In addition, the herbaceous hardwood is said to have silver in the body, so that the five intestines are comfortable, the mind and body are stabilized, the bad body can be driven out, and the body can be lightly lived for a long time. In the agreement, it is noted that silver is effective in preventing and treating psychiatric diseases such as epilepsy and game and cold disease. Silver, which is known for its benefits to the human body, is expensive and is mainly used only for expensive products.

Silver is a well-known material as a general-purpose antimicrobial agent. Colloidal silver is known to have excellent effects on bacteria, fungi and viruses, but also has no side effects. Particularly, in the case of nanosilver solution in which silver is dispersed into fine particles (1 to 5 nm), it easily penetrates into cells, thereby killing them by suffocating by stopping the function of enzymes required when viruses, bacteria, fungi and the like breathe. This is because the germ's metabolism is prevented and sterilized, and the silver's electrical load from the silver inhibits germ's reproductive function.

By using the antibacterial and deodorizing effect of silver, silver eluate which dissolved high purity silver with ions in mineral distilled water in electrolysis device is coated with fiber, paper, or mixed with food and beverage as in Korea Patent Application No. 2001-16100. In addition, attempts have been made to apply antimicrobial and deodorizing effects to fibers or the like by applying a nano-ized silver compound or colloidal silver to a polyurethane film or by coating or incorporating it into a film as in Korean Patent Application No. 2003-22819.

However, due to the high cost, there have been limitations in the practical use in food containers for single use.

Accordingly, the present invention has been made in order to solve the above problems, by applying a coating composition formed of expensive silver to the nanoparticle size, such as paper, starch, styrofoam, plastic disposable food packaging containers or lunch boxes, etc. In addition, it was possible to easily apply an antimicrobial coating composition containing silver having an antimicrobial effect in a large area, the present invention was completed based on this.

Accordingly, an object of the present invention is to provide an antimicrobial coating composition for food containers containing silver nano which can provide an antimicrobial effect to a disposable food container simply and cost-effectively.

The antimicrobial coating composition for food containers for achieving the object of the present invention is a monomer mixture selected from the group consisting of carboxylic acid containing styrene and ethylenically unsaturated groups and derivatives thereof in an aqueous phase containing an emulsifier and a polymerization initiator. After emulsion polymerization at a temperature of 60 to 85 ℃, prepared by adding 1 to 1000ppm silver nano solution, the copolymer obtained as a result of the emulsion polymerization has a glass transition temperature of 30 to 80 ℃.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1 is a flow chart showing a method for producing a coating composition for food containers according to the present invention, it will be described with reference to this.

As shown in FIG. 1, according to an embodiment of the present invention, water (preferably deionized water as a dispersion medium), an emulsifier, and a polymerization initiator, which are primary raw materials, are first introduced into a reactor to a temperature of 60 to 85 ° C. Raise the temperature. Thereafter, the mixture of the monomer mixture and the chain transfer agent, which are uniformly mixed in a separate container, is added dropwise to the reactor while stirring, and the polymerization reaction is carried out. After completion of the reaction, the reactants are aged at a temperature of about 80 ° C., and then room temperature. Cool to (about 30 ° C.). The dispersion is neutralized and then mixed with the nanosilver solution to finally prepare the coating composition of the present invention.

 As described above, the present invention relates to an antimicrobial coating composition for food containers containing nano silver, wherein the coating composition is dispersed in a copolymer having a glass transition temperature (Tg) of about 30 to 80 ° C. in a dispersion. Present, the polymerization is carried out by emulsion polymerization which is already well known in the art.

In general, in the case of emulsion polymerization, micelles are formed in an aqueous solution due to the hydrophilic and hydrophobic portions of the emulsifier, and the initiator is decomposed into radicals at the polymerization temperature and enters the micelles. At the same time, the monomer diffuses from the dispersed phase and enters the micelle to meet radicals and start the polymerization reaction. As the polymerization reaction proceeds, the monomer dispersed phase becomes smaller as the monomer is polymerized and diffused, and the micelles in which the polymerization takes place become larger and larger as polymer particles, thereby increasing the solid content.

As such, in the present invention, monomers, emulsifiers, water-soluble initiators and water (preferably deionized water as dispersion medium) are essentially used, preferably 0.1 to 4 parts by weight of emulsifier and 0.05 to 2 initiators based on 100 parts by weight of the monomer mixture. Parts by weight are used, and the amount of water is preferably adjusted so that the solids content in the reinforcing composition is about 20 to 60%.

The monomer used in the polymerization reaction is in the form of a mixture of two or more monomers selected from the group consisting of styrene and carboxylic acids containing ethylenically unsaturated groups and derivatives thereof, and particularly preferably ester derivatives as derivatives of the carboxylic acids containing ethylenically unsaturated groups. Do. In addition, it is preferable to use the monomer in the form of a mixture of two or more kinds in order to improve adhesion to the container. Representative examples of the monomers include n-butyl acrylate, methyl methacrylate, styrene, methacrylate, methacrylic acid, acrylic acid, ethyl acrylate, 2-ethylhexyl acrylate, itaconic acid, 2-hydroxyethyl methacrylate. And lauryl methacrylate. The chemical formulas of representative monomers that can be used and the glass transition temperatures (Tg) of these polymers are shown in Table 1 below.

Monomer Chemical formula Glass transition temperature of polymer (℃) n-butyl acrylate CH ₂ = CH-COO- (n) C ₄ H ₉ -54 Methyl methacrylate CH ₃ ｜ CH ₂ = C-COOCH ₃ 105 Styrene CH ₂ = CH- 100 Methacrylate CH ₂ = CH-COOCH ₃ 10 Methacrylic acid CH ₃ | CH ₂ = C-COOH 228 Acrylic acid CH ₂ = CH-COOH 106 Ethyl acrylate CH ₂ = CH-COOC ₂ H ₅ -24 2-ethylhexyl acrylate CH ₂ = CHCOO-CH ₂ -CH-C ₄ H ₉ | C ₂ H ₅ -85

In the present invention, as an emulsifier added to provide a polymerization site, anionic, cationic and nonionic emulsifiers commonly known in the art may be used. Anionic emulsifiers include soap, LAS (linear alkylbenzenesulfonate), SLS (laurylsulfate salt), SLES (laurylethersulfate salt), DOS (dioctylsulfosuccinate salt), alkylpropylsulfosite Cationic emulsifiers include stearyltrimethyl ammonium salts, benzalkonium, and nonionic emulsifiers include NP (nonylphenol) or EO (ethylene oxide) adducts of lauryl alcohol. have. The emulsifier may be used in the form of a single substance or mixture depending on the reaction characteristics of the monomer mixture.

 As described above, the emulsifier is used in the range of 0.1 to 4 parts by weight based on 100 parts by weight of the monomer mixture, if less than 0.1 parts by weight, the reaction is difficult to progress, there is a problem in the generation of lumps and the stability of the emulsion, and more than 4 parts by weight If there is a lot of bubbles in the manufacturing process there is a problem when using.

 The polymerization initiator may be used without particular limitation as long as it is a kind capable of initiating free radical polymerization, for example, potassium persulfate, ammonium persulfate, organic peroxide, hydrogen peroxide, which are known in the art. And redox system. The polymerization initiator is used in the range of about 0.05 to 2 parts by weight with respect to 100 parts by weight of the monomer mixture, if less than 0.05 parts by weight is difficult to proceed the reaction, if it exceeds 2 parts by weight problems in the stability of storage after the reaction There is this.

In addition to the components mentioned above, one or two or more of the additives may be reacted with a chain-transfer agent such as alkyl mercaptan, an electrolyte such as carbonate, sodium hydroxide, neutralizing agent such as aqueous ammonia, buffer, reducing agent, other supplements, or the like. It may be used in an appropriate amount depending on the conditions, such additive components are known in the art. For example, it is preferable to use up to about 2 parts by weight of the chain transfer agent (molecular weight regulator) and about 1 part by weight based on 100 parts by weight of the monomer mixture.

According to the invention, the above-mentioned polymerization reaction may be a batch process or a continuous process, preferably a reaction temperature of about 60 to 85 ℃ and an inert atmosphere (for example, nitrogen gas Under the atmosphere), but the reaction is carried out in various ways such as batch method, monomer addition method, emulsion addition method, seed method, but can be generally carried out by the following two methods.

First, in the monomer addition method, an emulsifier, water, and a polymerization initiator are initially added to a reactor, and a monomer mixture is continuously added while reacting for about 2 to 4 hours. In this case, the polymerization initiator may be optionally dissolved in water in a separate vessel and continuously added to the reactor with the addition of monomer. The above method has the advantage of easy removal of heat of polymerization, stability of polymerization, and particle size control.

Secondly, after the monomer mixture is emulsified in the emulsifier dispersion by the emulsion addition method, a part (about 10 wt% of the total monomer mixture) is introduced into the reactor and polymerized, followed by polymerization of the remaining monomer emulsion for about 2 to 5 hours continuously or stepwise. There is a way to react over. This method has the advantage of easy polymerization heat removal, the particle size distribution is wider than the monomer addition method.

As described above, although various methods can be used in the present invention, the above-mentioned two methods which are widely used are preferable, and among them, polymerization is most preferred according to the monomer addition method.

As a result of the completion of the above-mentioned polymerization, the copolymer has a glass transition temperature (Tg) of about 30 to 80 ° C. In addition, the weight average molecular weight of the copolymer is about 50,000 to 500,000, and the average particle diameter of the copolymer particles contained in the dispersion has about 0.05 to 0.5 탆 (500 to 5,000 kPa). In addition, the coating composition (dispersion) of the present invention is preferably to have a solid content of about 20 to 60%, which is a result of considering the ease of manufacture, storage distribution problems, mixing with other supplements and the like.

 The nanosilver solution used in the present invention uses a commercially available nanosilver distilled water dilution solution.

In the present invention, the nanosilver solution is added to include 1 to 1000 ppm of the nanosilver particles with respect to the entire coating composition.

The particle size of the nanosilver is 0.1 to 10 nanometers. The coating composition of the present invention is coated on the surface of the container when applied to the container surface for food and then dried. According to an embodiment of the present invention, the coating composition is mixed with water in a ratio of 4: 1, and is applied thinly on the surface of the food container to be coated, and dried in an oven at 100 to 170 ° C. for about 1 to 5 minutes. Cold packaging.

The coating composition of the present invention prepared as described above is not only usable for food containers because it is harmless to the human body, but also for food containers or lunch boxes made of disposable paper, starch, styrofoam, plastic, etc. When applied to the surface of the coating power is excellent, the nano silver contained in the composition of the present invention is uniformly distributed to be able to maintain the antibacterial effect continuously. Therefore, the use of the coating composition of the present invention has the advantage that can be used to reduce the cost and obtain expensive silver antibacterial effect.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention is not limited thereto.

Example 1

64 parts by weight of deionized water, 1 part by weight of an emulsifier (SLS), and 0.2 part by weight of a polymerization initiator (ammonium persulfate) were added into a reactor equipped with a circulation condenser and a stirrer, and the reactor was heated to 80 ° C. In a separate vessel, the monomer mixture consisting of 15 parts by weight of methyl methacrylate, 10 parts by weight of styrene and 10 parts by weight of n-butyl acrylate and 0.2 parts by weight of a chain transfer agent (lauryl mercaptan) are uniformly mixed, and then into the reactor. The reaction was carried out under stirring for 3 hours while dropping. At this time, the monomer mixture and the chain transfer agent were purged with nitrogen gas. After the end of the reaction the reactor contents were aged under stirring at 80 ° C. for 1 hour and then cooled to room temperature. Then, the dispersion was neutralized to pH 6.5 by adding ammonia water, and then 0.2% of nanosilver (5000 ppm) was added thereto.

The content of solids in the dispersion was 35.3%, the measured glass transition temperature of the copolymer was 58 ℃, the average particle diameter of the copolymer particles was 0.12㎛.

Example 2

38.2 parts by weight of deionized water and 0.7 parts by weight of emulsifier (SLES, NP 40 moles) were added to the reactor to which the circulation condenser and the stirrer were attached, and the reactor was heated to 75 ° C. In a separate vessel, 0.2 parts by weight of a monomer mixture consisting of 28 parts by weight of methyl methacrylate and 12 parts by weight of n-butyl acrylate and 0.2 parts by weight of a chain transfer agent (lauryl mercaptan) were added dropwise to the reactor, and then added to another container. 0.2 part by weight of a polymerization initiator (ammonium persulfate) was dissolved in 20 parts by weight of water, and reacted under stirring for 3 hours while dropping together. At this time, the mixture of the monomer mixture and the chain transfer agent was purged with nitrogen gas. After the end of the reaction the reactor contents were aged under stirring at 75 ° C. for 1 hour and then cooled to room temperature. Then, the aqueous dispersion was neutralized to pH 6.5 by adding ammonia water, and 0.4% of nanosilver (5000 ppm, nanotech) was added thereto.

The content of solids in the dispersion was 41.5%, the measured glass transition temperature of the copolymer was 57 ℃, the average particle diameter of the copolymer particles was 0.081㎛.

Table 1 shows the results of the antimicrobial effect of the antimicrobial coating composition according to the present invention, the measuring method of the antimicrobial effect is as follows.

* Antimicrobial test method

JIS Z 2801 antibacterial products-antibacterial test method, antibacterial effect (2000)

 Note) Test condition

 1. Test spawn

       Test organism 1: Staphyloccocus aureus ATCC 6538

       Test bacterium 2: Escherichia coli ATCC 8739

 2. Concentration and amount of inoculation

Test strain 1: 3.8 × 10 ⁶ / ml, 0.1 ml

Test bacterium 2: 1.1 × 10 ⁶ / ml, 0.1 ml

 3. Type and concentration of inoculum: 1/100 Nutrient broth

 4. Type and size of test piece: paper coated with the antimicrobial coating agent 50 × 50 mm

 5. Nonionic surfactant: Tween 80, 0.05% added to inoculum

division Bacteriostatic reduction rate (%) Test bacteria 1 Test bacteria 2 Example 1 99.9 99.9 Example 2 99.9 99.9

 As shown in Table 2 it was confirmed the excellent antimicrobial properties of the coating composition of the present invention.

The coating composition comprising nanosilver (silver nano) particles according to the present invention is a food prepared from disposable paper (pulp), starch, styrofoam, plastic, etc., which has been difficult to apply silver having excellent antimicrobial effect for conventional cost reasons. It is expected to be applicable to the manufacturing field of food containers, etc., which can maintain the freshness of foods for a long time while preventing the propagation of harmful germs, since it can be applied at a reduced cost for packaging containers or lunch boxes.

Claims (5)

A monomer mixture selected from the group consisting of carboxylic acids containing styrene and ethylenically unsaturated groups and derivatives thereof is emulsified in an aqueous solution containing an emulsifier and a polymerization initiator at a temperature of 60 to 85 ° C., and then 1 to 1 to the total reactants. It is prepared by adding a silver nano solution to a concentration of 1000ppm, the coating composition for a food container having an antimicrobial effect, characterized in that the copolymer obtained as a result of the emulsion polymerization has a glass transition temperature of 30 to 80 ℃. The coating composition of claim 1, wherein the nanosilver has a particle size of 0.1 to 10 nanometers. The coating composition of claim 1, wherein the copolymer has a weight average molecular weight of 50,000 to 500,000, and an average particle diameter of 0.05 to 0.5 μm. The method of claim 1, wherein the monomer is n-butyl acrylate, methyl methacrylate, styrene, methacrylate, methacrylic acid, acrylic acid, ethyl acrylate, 2-ethylhexyl acrylate, itaconic acid, 2-hydroxyethyl Coating composition for food containers, characterized in that selected from the group consisting of methacrylate and lauryl methacrylate.   The coating composition of claim 1, wherein the solid content in the composition is 20 to 60%.

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