JP7151294B2 - Freshness-keeping film, freshness-keeping sheet and package - Google Patents

Description

TECHNICAL FIELD The present invention relates to an antibacterial resin molded article, and more particularly to a freshness-keeping film, a freshness-keeping sheet, and a package used as a packaging material for the purpose of extending the freshness-keeping period of fruits and vegetables.

Conventionally, as antibacterial films used for food, there are films formed by kneading various antibacterial ingredients into plastic resins, and films in which antibacterial ingredients are applied to the surface of films. However, if the antibacterial component used is non-volatile, the antibacterial action is exerted only on the part where the film and food come into contact, and especially when the content is solid, the antibacterial action does not reach the entire content. there were.

In response to this, an antibacterial film using, for example, isothiocyanates, which are volatile antibacterial components, has been proposed, and antibacterial action can be expected even on parts where the film and food do not contact (Patent Document 1). .
However, this method has the drawback that the antibacterial component volatilizes or deteriorates under the influence of heat applied during the molding process of the resin because of its volatility, resulting in a decrease in the antibacterial effect. Furthermore, the antibacterial component tends to volatilize even after molding, making it difficult to control release.

As a means for solving these problems, a volatile antibacterial component is supported on a carrier (Patent Document 2), enclosed in cyclodextrin or the like, or used in microcapsules (Patent Document 3). , a method for reducing the effect of temperature in the molding process and obtaining sustained release of the antibacterial component has been proposed.

JP-A-3-151972 JP-A-3-178902 Japanese Patent Application Laid-Open No. 2007-230023

However, when the antibacterial component is supported on a carrier and contained in the resin, the amount of the antibacterial component contained in the resin molded product is reduced compared to the method in which the antibacterial component is directly contained in the resin without using a carrier or the like. end up Therefore, the amount of volatilization of the antibacterial component is small, and there is a possibility that a sufficient antibacterial effect cannot be obtained.

Therefore, in view of the above problems, the present invention provides a freshness-keeping film that can more efficiently release the antibacterial component out of the resin and can obtain a sufficient antibacterial effect even with a small amount of the antibacterial component. for the purpose.

The present invention was made to solve the above problems, and the first invention is
A freshness-keeping film comprising a resin layer containing carrier particles carrying a volatile antibacterial component, wherein the surface of the freshness-keeping film has an uneven structure.

With such a configuration, it is possible to impart a sustained release property by carrying the antibacterial component on the carrier, and by blending this in the film, a freshness-keeping film having an antibacterial effect can be obtained. Furthermore, by providing an uneven structure on the surface of the freshness-keeping film, it becomes possible to efficiently release the antibacterial component in the freshness-keeping film to the outside of the resin.

Moreover, the second invention of the present invention is
The uneven surface structure of the freshness-keeping film is composed of a set of protrusions, the arithmetic average of the distance d1 between adjacent protrusions is 1 μm or more and 50 μm or less, and the arithmetic average of the height h1 of the protrusions is 1 μm or more and 30 μm or less. It is a freshness-keeping film.

Furthermore, the third invention of the present invention is
The uneven surface structure of the freshness-keeping film is composed of a set of ridges, the arithmetic average of the distance d2 between adjacent ridges is 1 μm or more and 50 μm or less, and the arithmetic average of the width w of the ridges is 10 μm or more and 50 μm or less. and the arithmetic mean of the height h2 of the ridges is 1 μm or more and 30 μm or less.

A fourth aspect of the present invention is
The freshness-keeping film is such that the volatile antibacterial component is a natural component derived from any one of plants, mushrooms, and microorganisms.

A fifth aspect of the present invention is
The freshness-keeping film, wherein the support is silica, activated carbon, zeolite, mineral, metal, or metal oxide.

A sixth aspect of the present invention is
The freshness-keeping film according to any one of claims 1 to 5, wherein the amount of the volatile antibacterial component added is 5 to 10 parts by weight with respect to 10 parts by weight of the carrier.

A seventh aspect of the present invention is
7. The freshness-keeping film according to any one of claims 1 to 6, wherein the carrier particles carrying the volatile antibacterial component have an angle of repose of 20° or more and 40° or less.

The eighth invention of the present invention is
8. The freshness-keeping film according to any one of claims 1 to 7, wherein the amount of the support particles is 0.5 parts by weight or more and 5 parts by weight or less with respect to 100 parts by weight of the resin layer.

A ninth invention of the present invention is
A freshness-keeping sheet is characterized by comprising the freshness-keeping film.

A tenth aspect of the present invention is
A package comprising the freshness-keeping film according to any one of claims 1 to 5.

The freshness-keeping film of the present invention has an uneven structure on the surface of a resin layer containing carrier particles carrying a volatile antibacterial component. By increasing the surface area due to this uneven structure, when used as a freshness-keeping film, the volatilization rate of the antibacterial component from the resin layer increases, and the concentration of the antibacterial component in the space can be instantaneously increased. Therefore, it is possible to obtain a freshness-keeping film exhibiting a suitable antibacterial action even with a small amount of chemical added.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram schematically showing a freshness-keeping film according to an embodiment of the present invention, in which the uneven structure on the surface is a collection of projections; FIG. 2 is an explanatory view schematically showing another embodiment of the freshness-keeping film according to the present invention, in which the uneven structure of the surface is an array of ridges.

An embodiment of a freshness-keeping film according to the present invention will be described with reference to the drawings.
FIG. 1 is an embodiment of a freshness-keeping film according to the present invention, and shows a basic configuration of a freshness-keeping film 10 whose uneven surface structure is a collection of projections.
The freshness-keeping film 10 includes a resin layer 1 containing carrier particles 2 carrying a volatile antibacterial component, and has protrusions 3 as an uneven structure on the surface of the resin layer 1 .

FIG. 2 is another embodiment of the freshness-keeping film according to the present invention, and is a diagram showing the basic configuration of a freshness-keeping film 20 having an uneven surface structure of ridges.
The freshness-keeping film 20 includes a resin layer 1 containing carrier particles 2 carrying a volatile antibacterial component, and has ridges 4 as an uneven structure on the surface of the resin layer 1 .

(resin layer)
The resin used for the resin layer 1 is one or more resins selected from thermoplastic resins such as polyethylene, polyethylene terephthalate, polyethylene naphthalate, polypropylene, polystyrene, and ethylene-vinyl acetate copolymer (EVA). may include Moreover, the resin layer 1 preferably has a film thickness of 10 μm or more and 100 μm or less. Good workability and handleability can be obtained by having a film thickness within the above range.

(Antibacterial ingredient)
The volatile antibacterial component may include at least one component having both volatility and antibacterial properties among compounds produced by organisms such as plants, mushrooms, and microorganisms. More specifically, plant extracts that use essential oils and fragrances such as lavender extract, rose extract, lemon extract, grapefruit extract, orange extract, bergamot extract, mint extract, etc. and phytoncides obtained from trees such as cinnamon bark, cypress, pine, cedar, camphor, and hiba, allelochemicals, phytoalexin, and volatile components MVOC produced by microorganisms.

The volatile antimicrobial component used in the present invention may contain a plurality of the antimicrobial components described above. By using multiple ingredients, it can be expected to have the effect of widening the antibacterial spectrum and preventing the emergence of resistant bacteria.

(Carrier)
The carrier used for the carrier particles 2 carrying a volatile antibacterial component may be at least one fine particle selected from the group consisting of activated carbon, silica, zeolite, minerals, metals, and metal oxides. As for the size of the particles, those having an average particle size of 30 μm or less, preferably 10 μm or less, more preferably 5 μm or less are used. Particles larger than 30 μm are not desirable because they cause molding defects when molding the resin, and the thickness of the film or sheet must be increased. The above average particle size is an arithmetic mean value measured by a laser diffraction/scattering method.

The amount of the volatile antibacterial component added to the carrier must be appropriately adjusted according to the type of carrier used. A higher antibacterial action can be obtained as the amount of the antibacterial component added increases. However, if the antibacterial component is added in excess of the amount of liquid absorbed by the carrier, the antibacterial component seeps out of the carrier, which not only causes stickiness but also causes cohesion between the carriers. This is not preferable because it significantly lowers the fluidity and dispersibility of the particles 2 .

As a guideline for the amount to be added, the amount of the volatile antibacterial component to be added is in the range of 5 to 40 parts by weight, preferably in the range of 15 to 30 parts by weight, per 10 parts by weight of the carrier.
However, since the upper limit of the liquid absorption amount that can be carried differs depending on the type of carrier, it is necessary to check the fluidity of the carrier particles 2 obtained. Therefore, the amount of the antibacterial component to be added is set so that the angle of repose of the support particles 2 supporting the antibacterial component falls within the range of 20° or more and 40° or less. The angle of repose is measured by measuring the dynamic angle of repose based on the angle of repose measurement method. If the angle of repose is less than 20°, the amount of the antibacterial component added may be insufficient and a sufficient antibacterial effect may not be exhibited.

Regarding the amount of the support particles 2 supporting the volatile antibacterial component, the support particles 2 supporting the volatile antibacterial component are 0.5 parts by weight or more and 5 parts by weight per 100 parts by weight of the resin layer 1. The range is as follows. If it exceeds 5 parts by weight, resin molding becomes extremely difficult. On the other hand, if it is less than 0.5 parts by weight, the amount of the antibacterial component contained in the resin molded article is too small to exhibit sufficient antibacterial action.

(Film manufacturing method)
The freshness-keeping film of the present invention can be produced by various film-forming methods such as the T-die molding method. It is preferable to add carrier particles 2 carrying a volatile antibacterial component to a resin and mold at 200° C. or less. Molding at a temperature higher than 200° C. causes the deterioration of the volatile antibacterial component, or an extremely large amount of volatilization, which causes a decrease in antibacterial properties.

(Surface uneven structure)
The shape of the uneven structure on the surface of the resin layer may be a projection shape or a ridge shape. The projection shape may be one of hemispherical, semielliptical, triangular pyramidal, quadrangular pyramidal, cylindrical, and polygonal prismatic shapes, or a combination of multiple types.
Further, the ridged shape means that the cross section is shaped like a half-moon shape, like the cut end of kamaboko with a plate. For example, the ridge shape corresponds to an inverted U shape, a convex shape, an arch shape, and the like. The inverted U shape is a shape “∩” obtained by vertically inverting the letter “U”. Alternatively, it may be a semi-circular shape, a semi-elliptical shape, a combination of a square or rectangle and a semi-circle, or a combination of a square or rectangle and a semi-ellipse.

As shown in FIG. 1 and FIG. 2, the uneven structure of the present invention is preferably a set of the projection-shaped protrusions 3 or the ridge-shaped ridges 4 . The protrusions 3 are preferably formed so that the average distance d1 between adjacent protrusions is 1 μm to 50 μm, and the average height h1 of the protrusions is in the range of 1 μm to 30 μm.
Regarding the ridges 4, it is preferable that the arithmetic average of the distance d2 between adjacent ridges is 1 μm to 50 μm, the average width w of the ridges is 10 μm to 50 μm, and the average height h2 of the ridges is 1 μm to 30 μm. It is preferable to mold so that
In addition, the said average value is an arithmetic mean.

The protrusions 3 and the ridges 4 are formed by embossing by selecting a pattern of protrusions and recesses on rolls in the film forming process, sandblasting, or the like.
The finer the uneven structure, the greater the effect of increasing the surface area. I don't like it. Further, if the uneven structure is rough, the increase in surface area is small, so the antibacterial component cannot be released efficiently, which is not preferable.

Various additives can be optionally added to the freshness-keeping film of the present invention within a range that does not impair the antibacterial action. More specifically, curing agents, curing accelerators, antioxidants, leveling agents, fluidity modifiers, catalysts, fillers, antistatic agents, ultraviolet absorbers, plasticizers, lubricants, colorants, etc. can be added. can.

By making a bag using the freshness-keeping film of the present invention, it is possible to obtain packages in various forms. For example, a package may be formed by appropriately selecting from bag-making methods such as horizontal pillow, vertical pillow, gusset, three-sided seal, four-sided seal, and standing pouch. Furthermore, a plastic zipper can be provided at the outlet of these packages.

In the case of a package for fruits and vegetables, it is necessary to ensure respiration of the fruits and vegetables. Therefore, the gas permeability of the freshness-keeping film of the present invention may be adjusted by forming micropores, forming cracks, or thinning the film, and processed as MA packaging. Also, in the stage of bag making, an MA packaging bag may be produced by using the freshness-keeping film of the present invention on one side and using an existing MA packaging film on the other side for three-sided sealing. As the simplest processing, a punch hole may be provided in the packaging bag to ensure the breathing of fruits and vegetables. In addition, after the contents are put in, the bag can be made breathable by sealing it with a collar tie or tape instead of sealing it.

The freshness-keeping film of the present invention can also be used by laminating it with other resin films, paper, non-woven fabrics, and various materials derived from natural products. For example, when it is desired to provide a barrier property, a vapor-deposited thin film layer made of an inorganic oxide may be provided on the surface of the freshness-keeping film. It is not limited to these examples, and a laminate can be formed according to any application.

The freshness-keeping film of the present invention can exert its effect to the maximum by using it on contents such as fruits and vegetables that have many microorganisms, but the contents are not limited to fruits and vegetables. In addition to fruits and vegetables, fresh fish, meat, dairy products, unbaked sweets, baked sweets, cut rice cakes, and other perishable and processed foods, as well as wood, paper, clothing, and cultural assets, which may be contaminated with microorganisms. Anything can be saved as content.

The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these.

<Example 1>
First, 10 parts by weight of silica (trade name: Aerosil 200FDA, manufactured by Nippon Aerosil Co., Ltd.) as a carrier was allowed to carry 30 parts by weight of bergamot extract as a volatile antibacterial component to obtain carrier particles having an angle of repose of 35°. rice field.

Subsequently, as a resin, 95 parts by weight of linear low-density polyethylene: SP2040 (manufactured by Prime Polymer Co., Ltd.) and 5 parts by weight of the carrier particles described above are put into a twin-screw extruder, heated to 200 ° C., melted, and T-die A film having a film thickness of 100 μm was formed in the above. The film was embossed so that the average distance d1 of the projections forming the uneven structure was 50 μm and the average height h1 of the projections was 30 μm to obtain a freshness-keeping film.

The resulting film was cut into 15 cm squares, and two films were stacked and three packages were sealed to form a packaging bag. Four cherry tomatoes were placed in the bag, and the opening of the bag was closed with a collar tie. The bag was stored at 25°C, and after 7 days, the freshness-keeping performance and the growth of mold were observed with the naked eye. The term "freshness-keeping performance" as used herein refers to how much initial freshness can be maintained, using the presence or absence of wilting of cherry tomatoes and seepage of eluate as an index.
○: Good (Freshness is maintained)
△: Partially degraded (partially wilted and seeps out of eluate)
×: Remarkably deteriorated (withering and seepage of eluate occur in more than half)

<Example 2>
Support particles similar to those used in Example 1 were used.
Subsequently, the resin and film forming method were the same as in Example 1, and embossing was performed so that the average distance d1 of the protrusions forming the uneven structure was 1 μm and the average height h1 of the protrusions was 1 μm. , a freshness-keeping film was obtained.
Others were carried out in the same manner as in Example 1.

<Example 3>
Support particles similar to those used in Example 1 were used.
Subsequently, the resin and film forming method were performed in the same manner as in Example 1, and the average distance d2 of the ridges forming the uneven structure was 50 μm, the average width w of the ridges was 50 μm, and the height h2 of the ridges was 50 μm. Embossing was applied so that the average was 30 μm to obtain a freshness-keeping film.
Others were carried out in the same manner as in Example 1.

<Example 4>
Support particles similar to those used in Example 1 were used.
Subsequently, the resin and the film forming method were performed in the same manner as in Example 1, and the average distance d2 of the ridges forming the uneven structure was 1 μm, the average width w of the ridges was 10 μm, and the height h2 of the ridges was 10 μm. Embossing was applied so that the average was 1 μm to obtain a freshness-keeping film.
Others were carried out in the same manner as in Example 1.

<Comparative Example 1>
Support particles similar to those used in Example 1 were used.
Subsequently, the resin and the film-forming method were performed in the same manner as in Example 1, but a flat freshness-keeping film was obtained without performing the final formation of the concave-convex structure.
Others were carried out in the same manner as in Example 1.

<Comparative Example 2>
Support particles similar to those used in Example 1 were used.
Subsequently, the resin and the film forming method were the same as in Example 1, and embossing was performed so that the average distance d1 of the projections forming the uneven structure was 70 μm and the average height h1 of the projections was 30 μm. , a freshness-keeping film was obtained.
Others were carried out in the same manner as in Example 1.

<Comparative Example 3>
Support particles similar to those used in Example 1 were used.
Subsequently, the resin and film forming method were performed in the same manner as in Example 1, and the average distance d1 of the projections forming the uneven structure was 0.5 μm, and the average height h1 of the projections was 0.5 μm. It was embossed to obtain a freshness-keeping film.
Others were carried out in the same manner as in Example 1.

<Comparative Example 4>
Support particles similar to those used in Example 1 were used.
Subsequently, the resin and film forming method were performed in the same manner as in Example 1, and the average distance d2 of the ridges forming the uneven structure was 70 μm, the average width w of the ridges was 70 μm, and the height h2 of the ridges was 70 μm. Average is 30μm
embossed to obtain a freshness-keeping film.
Others were carried out in the same manner as in Example 1.

<Comparative Example 5>
Support particles similar to those used in Example 1 were used.
Subsequently, the resin and the film forming method were performed in the same manner as in Example 1, and the average distance d2 of the ridges forming the uneven structure was 0.5 μm, the average width w of the ridges was 5 μm, and the height of the ridges was 5 μm. Embossing was applied so that the average h2 was 0.5 μm to obtain a freshness-keeping film.
Others were carried out in the same manner as in Example 1.
The results of Examples 1 to 4 and Comparative Examples 1 to 5 are shown in Table 1.

From Examples 1 to 4 and Comparative Example 1, it was found that a flat film without an uneven structure on the surface could not sufficiently release the antibacterial component, and could not obtain freshness-keeping performance and antibacterial action.
From Example 1 and Comparative Example 2, even if the surface has an uneven structure as a set of protrusions, if the distance between the protrusions is too large as in Comparative Example 2, sufficient freshness-keeping performance and antibacterial action can be obtained. It turns out that you can't get it. Compared to the flat film of Comparative Example 1, the film of Comparative Example 2 has slightly higher freshness-keeping performance, so it is considered that the presence of the uneven structure increases the surface area and releases the antibacterial component. However, it has not yet achieved a sufficient effect. This is probably because the number of protrusions on the film surface was small and the effect of increasing the surface area was only slight.
In Comparative Example 3, the effect of increasing the surface area was expected by reducing the distance and height of the protrusions. . Film cracks and wrinkles originated from the carrier particles.

Furthermore, from Example 3, Example 4, Comparative Example 4, and Comparative Example 5, a comparison was also made in the case of using ridges as the concave-convex structure, and the results were the same as in the case of protrusions.
From these results, it was found that the present invention makes it possible to obtain a film capable of preserving the freshness of fruits and vegetables.

DESCRIPTION OF SYMBOLS 1... Resin layer 2... Carrier particle 3... Projection part 4... Ridge part 10... Freshness-keeping film 20... Freshness-keeping film

Claims (7)

A freshness-keeping film in which carrier particles carrying a volatile antibacterial component are blended in a resin layer, wherein the surface of the freshness-keeping film has an uneven structure, and the surface uneven structure of the freshness-keeping film has protrusions. A freshness-keeping film comprising a set of portions, wherein the arithmetic mean of the distance d1 between adjacent projections is 1 μm or more and 50 μm or less, and the arithmetic mean of the height h1 of the projections is 1 μm or more and 30 μm or less . A freshness-keeping film in which carrier particles carrying a volatile antibacterial component are blended in a resin layer, wherein the surface of the freshness-keeping film has an uneven structure, and the surface uneven structure of the freshness-keeping film has ridges. The arithmetic mean of the distance d2 between adjacent ridges is 1 μm or more and 50 μm or less, the arithmetic mean of the width w of the ridges is 10 μm or more and 50 μm or less, and the arithmetic mean of the height h2 of the ridges is 1 μm or more and 30 μm or less. The freshness-keeping film according to any one of claims 1 and 2, wherein said volatile antimicrobial component is a natural component derived from any one of plants, mushrooms and microorganisms. The freshness-keeping film according to any one of claims 1 to 3, wherein the carrier is silica, activated carbon, or zeolite. 5. The freshness-keeping film according to any one of claims 1 to 4, wherein the carrier particles carrying the volatile antibacterial component have an angle of repose of 20° or more and 40° or less. A freshness-keeping sheet comprising the freshness-keeping film according to any one of claims 1 to 5. A package comprising the freshness-keeping film according to any one of claims 1 to 5.

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