KR101802362B1 - Polylactic acid based-foaming extruded sheet containing inorganic antibiotics and biodegradable foam-molding product using the same - Google Patents

Abstract

The present invention relates to a polylactic acid-based extrusion foamed sheet containing an inorganic antibacterial agent and a biodegradable antibacterial foam molded product using the polylactic acid-based extrusion foamed sheet. The polylactic acid-based extrusion foamed sheet of the present invention is formed in a biodegradable foamed sheet formed of polylactic acid, or a composite degradable foamed sheet which contains polylactic acid as a main material, and in which a petrochemical resin is mixed with the polylactic acid within a range satisfying requirements of bio-based plastics considering strength, productivity and the like. The polylactic acid-based extrusion foamed sheet of the present invention is degraded in the natural state according to characteristics of polylactic acid-based materials by containing the inorganic antibacterial agent. The biodegradable antibacterial foam molded product using the polylactic acid-based extrusion foamed sheet according to the present invention is advantageous in maintaining freshness of breads, fruits, vegetables, mushrooms, cut meats and the like and preventing spoilage thereof since the polylactic acid-based extrusion foamed sheet according to the present invention maintains antibacterial properties and freshness from the inorganic antibacterial agent.

Description

TECHNICAL FIELD The present invention relates to an antimicrobial polylactic acid-based extruded foam sheet containing an inorganic antibacterial agent and a biodegradable antibacterial foamed molded article using the same. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antimicrobial polylactic acid-

The present invention relates to an antimicrobial polylactic acid-based extruded foam sheet containing an inorganic antibacterial agent and a biodegradable antibacterial foamed article using the same. More particularly, the present invention relates to a biodegradable foam sheet comprising polylactic acid or polylactic acid as a main ingredient, In consideration of productivity and the like, the polylactic acid is composed of a complex-decomposable foam sheet obtained by mixing a petrochemical resin with the polylactic acid in a range satisfying the requirements of the bio-based plastics. By containing the inorganic antibacterial agent, To an antimicrobial polylactic acid-based extruded foam sheet containing an inorganic antibacterial agent, which is decomposed in a natural state and maintained in antimicrobial activity and freshness from an inorganic antimicrobial agent, and a biodegradable antibacterial foamed article using the same.

Conventionally, foams composed of general-purpose resins such as polyethylene-based resin, polypropylene-based resin and polystyrene-based resin have been widely used for various fields for a long time because of their excellent lightweight property, heat insulating property and buffering property.

However, most of the foam composed of the general-purpose resin is not decomposed when left in a natural environment after use. Recently, a poly (lactic acid) (PLA) derived from plants has been substituted for the general- Resin is attracting attention.

PLA resin is a thermoplastic resin which is made from a plant such as corn as a starting material and which is decomposed into carbon dioxide and water even if it is left in a natural environment after use. Therefore, the PLA resin is expected to be used as an environment-friendly plant-derived general-purpose resin for foaming showing degradability in a natural environment. Research has been conducted on a foam made from a PLA resin as a raw material. Development is underway.

For example, Japanese Patent Application Laid-Open No. 2002-322309 discloses a polylactide-based resin foam which is uniformly and finely foamed by extruding and foaming a polylactide resin, and foamed at a high magnification. However, since the above-mentioned foam contains amorphous polylactide as a main component, there is a problem in that it is excellent in moldability but has a problem in heat resistance and deforms at room temperature.

Therefore, when the crystalline polylactide is contained in order to improve the heat resistance of the PLA resin, the heat resistance can be expected to be improved. On the other hand, there is a problem in foaming property and heat generation property and the function equivalent to that of the conventional sheet or plate polystyrene resin foam Can not be obtained.

In particular, PLA resins are produced from 100% renewable raw materials and are used in bottles, films, containers, fibers, etc., and are environmentally friendly enough to be used in medical applications such as sutures, plates and bone fixation screws.

Recently, antimicrobial PLA based on PLA resin has been reported, and the deodorization and antimicrobial properties of PLA film containing TiO 2 nanoparticles as a photocatalyst have been reported [Journal of the Dyeing and Finishing Society of Korea, 2008, Vol. 20, 1 ~ 7], and PLA antimicrobial yarn for PLA antioxidation with a phytonide-based organic antimicrobial agent incorporated into PLA yarn [Journal of the Dyeing and Finishing Society of Korea, 2011, 45th Conference 2011, Vol. 04, 52].

However, the known antimicrobial PLA-related products are non-inclusive and can not be used as degradable extruded foams for application in food container applications.

As a result of various efforts to obtain a biodegradable extruded foam suitable for application in the field of food containers, the present inventors have found that a biodegradable foam sheet comprising polylactic acid or polylactic acid as a main material, By mixing a petrochemical resin with lactic acid to optimize the material of the polylactic acid polymer resin and providing an extruded foam sheet containing an inorganic antimicrobial agent, it is decomposed in a natural state according to the polylactic acid-based material characteristic, The present invention has been accomplished by confirming that it is beneficial to maintain the freshness of breads, fruits, vegetables, mushrooms, and cut meat and to prevent their decay.

It is an object of the present invention to provide an antibacterial polylactide-based extruded foam sheet which contains an inorganic antibacterial agent and optimizes the material of the polylactic acid polymer resin.

Another object of the present invention is to provide a biodegradable antibacterial foamed article using an antibacterial polylactide-based extruded foam sheet.

In order to achieve the above object, the present invention provides a biodegradable polymer resin comprising a polylactic acid polymer; 0.05 to 4 parts by weight of a chain extender, 0.01 to 4 parts by weight of a foam nucleating agent and 0.01 to 4 parts by weight of a polylactic acid polymer composition comprising 100 parts by weight of a polylactic acid polymer composition consisting of a biodegradable resin comprising a polylactic acid and a polylactic acid, 0.1 to 5 parts by weight of an antimicrobial agent are mixed to provide a compressed foamed antimicrobial polylactide-based extruded foam sheet.

In the antibacterial polylactide-based extruded foam sheet of the present invention, the inorganic antimicrobial agent is preferably a mineral obtained by ion-exchanging an antimicrobial metal.

Wherein the mineral comprises 62.0-68.0 wt% SiO _2, 18.0-25.0 wt% Al ₂ O _3, 1.3-2.5 wt% Fe ₂ O _3, 0.1-1.9 wt% MgO, 0.05-1.5 wt% Na ₂ O, and K ₂ O 5.0 to 8.0% by weight.

Further, another inorganic antimicrobial agent may be selected from nanoparticles composed of any one of transition metal oxides selected from the group consisting of zirconium, titanium, zinc, copper, and combinations thereof, or a mixture thereof.

In the antimicrobial polylactide-based extruded foamed sheet of the present invention, the polylactic acid polymer composition is composed of crystalline polylactic acid alone or from 55 to 98% by weight of crystalline polylactic acid and 2 to 45% by weight of amorphous polylactic acid.

The polylactic acid polymer composition comprises 60 to 99% by weight of a biodegradable resin containing polylactic acid and 1 to 40% by weight of a petrochemical resin.

The present invention provides a biodegradable antibacterial foamed article which is applied to a food container or a food container packaging material in which the antibacterial polylactide-based extruded foam sheet is molded.

The present invention can provide an antibacterial polylactide-based extruded foam sheet by optimizing the material of the polylactic acid polymer resin as a biodegradable material in consideration of the strength and productivity of the final product and containing an inorganic antibacterial agent.

Accordingly, the present invention is to provide an antimicrobial agent and an antimicrobial property from an inorganic antimicrobial agent while retaining the polylactic acid-based material characteristic, thereby preserving freshness and preserving freshness of breads, fruits, vegetables, mushrooms and cut meat, , And a biodegradable antibacterial foamed molded article obtained by molding the same can be provided.

FIG. 1 is a result of observing the storage state of the bread for 10 days after storing the bread according to the embodiment of the present invention and the tray of Comparative Example 1. FIG.

Hereinafter, the present invention will be described in detail.

The present invention relates to a biodegradable polymer resin comprising a polylactic acid polymer; 0.05 to 4 parts by weight of a chain extender, 0.01 to 4 parts by weight of a foam nucleating agent and 0.01 to 4 parts by weight of a polylactic acid polymer composition comprising 100 parts by weight of a polylactic acid polymer composition consisting of a biodegradable resin comprising a polylactic acid and a polylactic acid, 0.1 to 5 parts by weight of an antimicrobial agent are mixed to provide a compressed foamed antimicrobial polylactide-based extruded foam sheet.

In the antimicrobial polylactide-based extruded foamed sheet of the present invention, the biodegradable polymeric resin material may contain only polylactic acid resin or contain polylactic acid as a main material. However, in view of strength and productivity, it is possible to use a polylactic acid polymer composition in which the material of the complex decomposing polymer resin in which the petroleum resin is mixed with the polylactic acid is optimized.

Hereinafter, the characteristics of each composition of the composition will be described in detail.

1) Polylactic acid polymer composition

The polylactic acid polymer composition of the first embodiment of the present invention is composed of crystalline polylactic acid alone or from 55 to 98% by weight of the crystalline polylactic acid and 2 to 45% by weight of the amorphous polylactic acid.

Lactic acid, which is a raw material of polylactic acid, has optical isomers of L-lactic acid and D-lactic acid because it has an arrangement of carbon atoms showing optical activity in molecules. Furthermore, it is present as poly-L-lactic acid (hereinafter referred to as "PLLA") and poly-D-lactic acid (hereinafter referred to as "PDLA").

The crystalline polylactic acid in the present invention refers to a case where the proportion of L-lactic acid in PLLA and the proportion of D-lactic acid in PDLA is high in polylactic acid, that is, when the optical purity is high, the crystalline is high and the heat resistance and mechanical properties are excellent .

Further, another polylactic acid polymer composition of the present invention comprises 55 to 98% by weight of the crystalline polylactic acid and 2 to 45% by weight of the amorphous polylactic acid, wherein the crystalline polylactic acid exhibits impact resistance and heat resistance , Flexibility is imparted by the amorphous polylactic acid polymer, and the physical properties are improved. Particularly, since the content of the amorphous polylactic acid is less than that of the crystalline polylactic acid, flex resistance is improved and the change in shape of the molded article due to heat can be minimized.

If the amorphous polylactic acid is contained in an amount of less than 2% by weight, the effect of the amorphous polylactic acid polymer can not be expected. If the amorphous polylactic acid is contained in an amount exceeding 45% by weight, Transition to amorphous nature, resulting in final shape changes. More preferably, by blending 2 to 30% by weight, and most preferably 2.5 to 10% by weight, of amorphous polylactic acid in the crystalline polylactic acid, not only the impact resistance and molding stability of the polylactic acid resin but also the heat resistance Stability.

The polylactic acid polymer composition of the second embodiment of the present invention comprises 60 to 99% by weight of a biodegradable resin containing polylactic acid and 1 to 40% by weight of a petrochemical resin.

The biodegradable resin containing polylactic acid includes the polylactic acid (hereinafter referred to as "PLLA") and poly-D-lactic acid (hereinafter referred to as "PDLA") described in the first embodiment, And may further include a biodegradable resin.

Preferred biodegradable resins include polyhydroxyalkanoates (PHA), polybutylene terephthalate (PBAT), polybutylenesuccinate-co-adipate (PBSA), polybutylene terephthalate Polybutylene succinate (PBS), polyvinyl alcohol (PVA), poly glycolic acid (PGA), polyvinyl pyrrolidone (PVA), polyvinyl pyrrolidone ) And polycaprolactone (PCL), or a mixture of two or more thereof.

As the petrochemical resin, it is preferable to use any one or a mixture of two or more selected from among polyethylene, polypropylene, polyester, polycarbonate, polyacrylic, ethylene vinyl acetate or thermoplastic resin of polyvinyl chloride. In addition to the proposed polymeric resin, there is no particular restriction on the use of the polymeric resin.

In the present invention, at least one selected from the group consisting of polyethylene and polypropylene is preferably used. In this case, the petrochemical resin is contained in an amount of 1 to 40% by weight. When the content of the biodegradable polymer resin is less than 1% by weight, the degradability is improved but the improvement in heat resistance is insufficient. On the other hand, if the content of the petrochemical resin is more than 40% by weight, there is a problem that the period of time required for resolution increases.

The composite degradable foam sheet according to the second embodiment of the present invention is produced from the composite degradable polymer resin composition obtained by mixing the biodegradable resin and the petrochemical resin commonly used as foams to provide a biodegradable polymer resin with a cost, , Strength and productivity.

Thus, the complex decomposable polymer resin composition is decomposed by light, heat, microorganisms, and chemical decomposition even though the decomposition period of the biodegradable resin is longer than 1 to 2 years, rather than 6 to 12 months. Adjustable, and improved productivity to meet price competitiveness.

2) Inorganic antibacterial agent

In the antibacterial polylactide-extruded foam sheet of the present invention, the inorganic antimicrobial agent of the first embodiment is preferably a mineral ion-exchanged with an antimicrobial metal.

The mineral is a mineral having a layered structure, easy to purchase, low cost, and high foaming rate. Wherein the mineral component comprises 62.0-68.0 wt% of SiO _2, 18.0-25.0 wt% of Al ₂ O _3, 1.3-2.5 wt% of Fe ₂ O ₃ , 0.1-1.9 wt% of MgO, 0.05-1.5 wt% of Na ₂ O, Minerals containing 5.0 to 8.0% by weight of K ₂ O are used.

The particle size of the mineral used in the present invention is preferably from 0.001 to 0.005 mm, and the range is selected so as not to affect the compatibility with other components.

In the embodiment of the present invention, silver (Ag) ion is selected as the antibacterial metal, but any known antimicrobial metal ion may be used. Preferably, any one selected from the group consisting of Ag, Fe, Zn, and Cu can be used.

The way in which the antimicrobial metal ions are introduced into the mineral may be introduced by exchanging a portion of potassium or sodium present in the mineral with the antimicrobial metal ions. Specifically, potassium or sodium in the mineral is ionized and separated from the mineral, and instead the antimicrobial metal ion is bound to the mineral, so that ion exchange can be carried out.

As described above, by ion-exchanging the antimicrobial metal, denaturation of the antimicrobial metal ion can be suppressed, the life of the antibacterial performance can be prolonged, and the discoloration can be minimized.

When the antimicrobial metal ion-exchanged mineral of the first embodiment is used as the inorganic antimicrobial agent of the present invention, the amount is preferably 0.1 to 5 parts by weight, more preferably 0.5 to 3 parts by weight per 100 parts by weight of the polylactic acid polymer composition To use the part. If the amount is less than 0.1 part by weight, the antibacterial performance is insufficient. If the amount is more than 5 parts by weight, economical efficiency is not preferable.

In the antibacterial polylactide-based extruded foam sheet of the present invention, as the inorganic antibacterial agent of the second embodiment, any one transition metal oxide selected from the group consisting of zirconium, titanium, zinc, copper, and combinations thereof is used . In the embodiment of the present invention, nanoparticle size ZnO is used.

At this time, the nanoparticles of the transition metal oxide can be surface-treated to be hydrophilic or hydrophobic and contained in the form of nanoparticles, thereby minimizing discoloration while maintaining antibacterial performance.

The inorganic antibacterial agent of the second embodiment is preferably used in an amount of 0.1 to 5 parts by weight, more preferably 0.1 to 3 parts by weight, and most preferably 0.5 to 1 part by weight, based on 100 parts by weight of the polylactic acid polymer composition .

Further, the inorganic antimicrobial agent of the present invention can be used singly or in combination with the inorganic antibacterial agent selected in the first or second embodiment.

3) chain extender

The polylactic acid to be used in the present invention has poor molecular weight even if it is well dried in water, and it is difficult to proceed with the post-treatment due to a problem that the polylactic acid is scarcely broken due to lack of strength. Therefore, for the purpose of increasing the molecular weight of the polylactic acid, ) Is used.

As a preferred example of the chain extender used in the present invention, there is preferably used a chain extender comprising bisphenol A diglycidyl ether, terephthalic acid diglycidyl ether, trimethylolpropane diglycidyl ether and 1,6-hexanediol diglycidyl ether An epoxy-based compound selected from the group; Or an isocyanate compound selected from the group consisting of hexamethylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate and triisocyanate; Or an acrylic compound is used.

At this time, when the chain extender is used in an amount of 0.05 to 4 parts by weight, more preferably 0.1 to 2 parts by weight, based on 100 parts by weight of the polylactic acid, the heat resistance improving effect is remarkable. If the content of the chain extender is less than 0.05 parts by weight, the effect of increasing the molecular weight is insufficient and can not be formed into a sheet. If the content of the chain extender is more than 4 parts by weight, crystallinity and heat resistance are improved. However, .

4) Foam nucleating agent

The foam nucleating agent used in the present invention may be selected from known materials. As an example thereof, an inorganic foaming nucleating agent such as talc or silica or an organic foaming nucleating agent such as calcium stearate may be used. May be added as a form. When the master batch is prepared, a dispersant or the like may be further added to control the dispersibility of the foam nucleating agent. In addition, a dispersant may be added in place of the dispersant in the preparation of the masterbatch. As the dispersing agent, stearamide amide may be used.

The foaming agent preferably contains 0.01 to 4 parts by weight based on 100 parts by weight of the polylactic acid polymer composition. When the content is less than 0.01 part by weight, the polylactic acid resin particles can be sufficiently foamed If the amount is more than 4 parts by weight, the function of the further foaming nucleating agent can not be expected, and there is a fear that the expanded particles and the fusion-bonding property of the obtained expanded particles in molding are insufficient.

On the first extruder, the foaming agent is pressed together with the above-mentioned polylactic acid resin particles and the foam nucleating agent, and the content of the foaming agent is 1 to 30 parts by weight, preferably 3 to 20 parts by weight. Examples of the foaming agent include propane, isobutane, n-butane, cyclobutane, isopentane, n-pentane, cyclopentane, isohexane, n-hexane, cyclohexane, trichlorofluoromethane, dichlorodifluoromethane, 1-chloro-1,1-difluoroethane, 1,1-difluoroethane, 1-chloro-1,2 , 2,2-tetrafluoroethane, nitrogen, carbon dioxide, argon, air and the like. Of these, physical foaming agents free from destruction of the ozone layer and being inexpensive are preferable. Specific examples thereof include nitrogen, air, carbon dioxide . Further, carbon dioxide is preferable in that expanded particles having a smaller apparent density are obtained relative to the amount of the foaming agent used. Further, two or more kinds of foaming agents such as carbon dioxide and isobutane may be used in combination.

Further, the present invention provides a biodegradable antibacterial foamed article to which the antibacterial polylactide-based extruded foam sheet is applied to a molded food container or food container packaging material.

An example of a specific molded article can be applied to food trays, cups, cup noodles, lunch boxes, and other food container packaging materials.

Through the embodiments of the invention, the antimicrobial polylactide-based food trays for the production by molding the extruded foam sheet of the present invention is eluted as low as less hazardous minutes reference value and securing the food and on contact safety Table 2, The antimicrobial activity achieving the target activity value for E. coli, P. aeruginosa, P. aeruginosa and Salmonella is realized [ Table 3 ].

Further, the inorganic antibacterial agent containing in poly biodegradable performance of the lactic acid-based extruded foam sheet are retained, and Table 4, since in the constant temperature and humidity conditions of 30 ℃ food freshness preservation for 10 days, breads, fruit, vegetables, mushrooms, cut It is possible to confirm that it is advantageous to maintain the freshness of the meat and the like and to prevent their corruption.

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

The present invention is intended to more specifically illustrate the present invention, and the scope of the present invention is not limited to these embodiments.

< Example  1>

10% by weight of amorphous polylactide (trade name: Revode 101, manufactured by Zhejiang Hisun Biomaterials) was mixed with 90% by weight of a crystalline polylactide resin (Revode 190, manufactured by Hisun) to prepare a basic resin composition containing polylactide. Based on 100 parts by weight of the polylactide-based polymer composition, 1.0 part by weight of an epoxy chain extender as a chain extender, 1.8 parts by weight of talc having a size of 0.1 to 5 mu m as a nucleating agent, 1.0 part by weight of acetyl tributyl citrate 1 part by weight of a silver ion-exchanged mineral as an inorganic and an inorganic antimicrobial agent was mixed well using a general mixer such as a tumbling mixer and then pellets of a uniform composition were prepared using a twin screw extruder having an inner diameter of 65 mm, The pellets were poured into a first extruder having an inner diameter of 90 mm, and extruded foam sheets were produced using a tandem type extruder connected to a first extruder having an inner diameter of 90 mm and a second extruder having an inner diameter of 120 mm. The polylactic acid resin particles were fed to a first extruder, heated and melt kneaded, and then 2.5 parts by weight of butane as a blowing agent was injected into the first extruder and the retention time was maintained at 10 minutes.

At this time, the heating and melting temperature was maintained at 170 to 230 占 폚 based on the resin temperature. Then, the temperature of the melt-mixing reaction product was slightly reduced in the second extruder connected to the first extruder so that the resin temperature was 120 to 150 ° C. Thereafter, the resultant was extruded from a ring-shaped die having a circular cross-section with a diameter of 110 mm and a slit interval of 0.5 mm, and was foamed cylindrically, and the cylindrical foamed material was cooled and discharged in the extrusion and extrusion directions to obtain a foamed sheet.

< Example  2 to 3>

The extruded foam sheet was obtained in the same manner as in Example 1 except that 2 parts by weight and 3 parts by weight of the silver (Ag) ion-exchanged mineral as the inorganic antibacterial agent were respectively contained.

< Example  4-5>

An extruded foamed sheet was obtained in the same manner as in Example 1 except that 1 part by weight of ZnO and 1.5 parts by weight of an inorganic antibacterial agent were contained.

< Example  6>

An extruded foamed sheet was obtained in the same manner as in Example 1 except that 1 part by weight of a silver ion-exchanged mineral as an inorganic antimicrobial agent and 0.5 part by weight of ZnO were contained in a mixed form.

< Example  7>

The extruded foam sheet was obtained in the same manner as in Example 1, except that 0.5 parts by weight of silver (Ag) ion-exchanged mineral as an inorganic antibacterial agent and 1 part by weight of ZnO were mixed.

< Example  8>

An extruded foam sheet was obtained in the same manner as in Example 1, except that a composite degradable polymer resin composition consisting of 80% by weight of crystalline polylactic acid (PLA Revode 190 from Hisun Co., Ltd.) and 20% by weight of a polyethylene resin was used .

< Comparative Example  1>

An extruded foamed sheet was obtained in the same manner as in Example 1, except that no inorganic antimicrobial agent was added.

< Experimental Example  1> Property evaluation

The properties of the extruded foamed sheets prepared in Examples 1 to 7 were measured and the results are shown in Table 1 below.

From the physical properties results shown in Table 1, the polylactide-based extruded foamed sheet containing an inorganic antibacterial agent exhibited heat resistance resistant to 70 ° C water for 10 minutes since all of the polylactide-based extruded foamed sheet had no deformation while being immersed in water at 70 ° C for 10 minutes. In addition, the tensile strength measurement results also satisfied the evaluation criteria.

< Experimental Example  2> Hazardous component release evaluation

The extruded foamed sheets prepared in Examples 1 to 7 were matured for a certain period of time and then molded into a product mold to prepare food trays. According to the testing method of the food instrument and container packaging process, Environmental Testing Laboratory) to perform dissolution test of harmful components, and the results are shown in Table 2 below.

From the results shown in Table 2, the food tray formed with the polylactide-based extruded foam sheet containing the inorganic antibacterial agent of the present invention is suitable for application to food containers by confirming that the harmful components are eluted at a low level, The safety of the system was confirmed.

< Experimental Example  3> Antibacterial performance evaluation

The extruded foam sheet containing the inorganic antibacterial agents prepared in Examples 1 to 7 was aged for a certain period and then molded into a product mold to produce a food tray and commissioned by an accredited certification body The antibacterial performance was evaluated and the results are shown in Table 3 below.

As a result of the evaluation of antibacterial activity in Table 3, the food tray formed with the polylactide-based extruded foam sheet containing the inorganic antibacterial agent showed the same results as those of the polylactide-based extruded foam sheet containing no inorganic antibacterial agent, Showed superior antimicrobial activity against various strains presented.

< Experimental Example  4> Evaluation of biodegradability

The extruded foam sheet containing the inorganic antibacterial agent prepared in Example 1 was aged for a certain period of time and molded into a product mold to prepare a tray for food and submitted to an authorized certification body (FITI test institute) for biodegradation And the results of the biodegradation analysis measurement are shown in Table 4 below. At this time, according to KS M ISO 14855-1, the test method was a method of measuring aerobic biodegradation of a plastic material under composting conditions and a method of carbon dioxide.

From the measurement results of Table 4, the biodegradability of the test substance with respect to the standard substance was calculated, and the results are shown in Table 5.

< Experimental Example  5> Freshness evaluation

The bread was placed in a food tray using the extruded foam sheet containing the inorganic antibacterial agent prepared in Examples 1 and 2, and then kept for 10 days under the constant temperature and humidity conditions maintained at 30 ° C, and the state was observed .

The results are compared with those of the general tray of Comparative Example 1, and the result is shown in FIG.

As a result, in the tray of Comparative Example 1, fungus was generated from the 5th day and a large amount of mold was formed on the 10th day. However, when stored in the tray manufactured in Example 1 and Example 2, No mold formation was observed.

As described above, the present invention provides a polylactide-based extruded foam sheet in which the polylactic acid polymer composition is optimized as a biodegradable material to improve strength and productivity along with biodegradability, and an antibacterial agent containing an inorganic antibacterial agent to achieve antibacterial properties .

Thus, the food container prepared by molding and processing the antimicrobial polylactide-based extruded foam sheet of the present invention has a structure in which the harmful component is eluted to a level lower than the standard value, the safety is secured when it comes in contact with food, and the antimicrobial activity against Escherichia coli, And preserves the freshness under constant temperature and humidity conditions at 30 ° C. Therefore, it is advantageous in maintaining the freshness of breads, fruits, vegetables, mushrooms, and cut meat and preventing their decay.

Further, the present invention can be applied to a biodegradable antibacterial foamed molded article comprising a food container or a food container packaging material.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art.

Claims (7)

A biodegradable polymer resin comprising a polylactic acid polymer; or
100 parts by weight of a polylactic acid polymer composition comprising a biodegradable resin including a polylactic acid and a complex decomposing polymer resin comprising a petrochemical resin,
0.05 to 4 parts by weight of a chain extender,
0.01 to 4 parts by weight of any one of the foaming agents selected from the group consisting of talc, silica and calcium stearate,
1 to 30 parts by weight of a physical foaming agent and
0.1 to 5 parts by weight of an inorganic antibacterial agent are mixed and foamed under compression,
Wherein the inorganic antimicrobial agent is a mineral ion-exchanged with an antimicrobial metal; Or a nanoparticle of a transition metal oxide; or an antimicrobial polylactide-based extruded foam sheet in which discoloration is suppressed. The antibacterial polylactide-based extruded foam according to claim 1, wherein the antimicrobial metal ion-exchanged mineral is one selected from the group consisting of Ag, Fe, Zn and Cu ion-exchanged with ions in the mineral. Sheet. The antimicrobial polylactide system according to claim 1, wherein the nanoparticles of the transition metal oxide are nanoparticles of any transition metal oxide selected from the group consisting of zirconium, titanium, zinc, copper, and combinations thereof Extruded foam sheet. The method of claim 2, wherein the mineral is SiO ₂ 62.0~68.0 wt%, Al ₂ O ₃ 18.0~25.0 wt.%, Fe ₂ O ₃ 1.3~ 2.5 wt%, MgO 0.1~1.9% by weight, Na ₂ O 0.05~1.5 By weight and K ₂ O in an amount of 5.0 to 8.0% by weight based on the total weight of the foamed polylactide-based foamed sheet. The polylactic acid polymer composition according to claim 1, wherein the polylactic acid polymer composition
Crystalline polylactic acid alone or in combination with
55 to 98% by weight of crystalline polylactic acid and 2 to 45% by weight of amorphous polylactic acid. The polylactic acid polymer composition according to claim 1, wherein the polylactic acid polymer composition
60 to 99% by weight of a biodegradable resin containing polylactic acid and 1 to 40% by weight of a petrochemical resin. A biodegradable antibacterial foamed article, wherein the antibacterial polylactide-based extruded foam sheet of any one of claims 1 to 6 is molded into a food container or food container packaging material.

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