JPH04359028A - Antifungal stretch film for food packaging - Google Patents

Abstract

PURPOSE:To obtain the title film excellent in transparency, gloss and self-tack by providing a resin composition containing straight chain low-density polyethylene, etc., with a layer containing a cyclodextrin clathrate compound containing hinokitiol, etc. CONSTITUTION:(A) A straight chain low-density polyethylene and/or ethylene- vinyl acetate copolymer or a resin composition comprising these polymers as principal components and (B) another resin composition incorporated with at least one compound including a cyclodextrin clathrate compound containing hinokitiol, its salt or both of them are subjected to melt extrusion with separate extruders, respectively, and then subjected to inflation forming through an annular double-layer die, thus giving the objective film made up of double layers containing 0.1-5000mg (in terms of hinokitiol) of the cyclodextrin clathrate compound per m<2> of the film.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an antibacterial stretch film for food packaging, and more particularly, to an antibacterial stretch film for food packaging.
This invention relates to a stretch film for food packaging that has excellent self-adhesive properties and antibacterial properties.

0002

[Prior Art and Problems to be Solved by the Invention] Stretch packaging, in which fresh foods such as fruits and vegetables, fresh fish, and meat are packaged directly or on plastic trays while stretching the film, has been widely used with the development of supermarkets, and is now widely used. Nowadays, it has become widely used as an essential packaging method. And recently, this stretch packaging is
Going one step further than simply improving product value through food display effects, preventing the adhesion of germs, or preventing packaged items from drying out, there is now a need to maintain the freshness of packaged items. There is. Under such circumstances, for example, there are concerns that the freshness of food can be maintained by sterilizing the packaging film and container itself, and that the freshness of food can be maintained due to the volatilization of antibacterial substances from the packaging film and container itself. From the viewpoint of food maintenance, substances that suppress the growth of microorganisms and are safe should be adsorbed onto appropriate articles, such as various packaging materials and adhesives, and brought into contact with food surfaces, or such packaging Methods of coating or packaging foods with materials have been proposed (for example, Japanese Patent Application Laid-Open No. 108359/1983, Japanese Patent Application Laid-open No. 302442/1989).
Publication No., JP-A-2-302451, JP-A-2-2
74763, JP 2-292201, JP 3-39363, JP 3-43456, JP 3-43457, JP 1-3067
Publication No. 34).

On the other hand, in general food packaging, silver, copper,
Antibacterial agents in which metal ions such as zinc, gold, and platinum are supported on inorganic silicon compounds, for example, films made from compositions made by kneading inorganic substances such as antibacterial zeolite into thermoplastic resin, have significantly improved transparency. Moreover, it was difficult to add an amount sufficient to produce a sufficient effect. Particularly in the case of stretch films for food packaging, properties such as transparency, gloss, and self-adhesiveness are important, but conventional methods are unable to fully satisfy any of these properties. (For example, Japanese Patent Application Laid-Open No. 3-348
Publication No. 51). In this way, we have developed a stretch film for food packaging that has antibacterial properties without reducing the properties of the stretch film for food packaging that has been traditionally used.
The current situation is that it has not been proposed yet.

0004

[Means for solving the problem] Therefore, the present inventors
We conducted extensive research to solve the problems of conventional films mentioned above and develop an antibacterial stretch film for food packaging that has excellent transparency, gloss, and self-adhesiveness. As a result, it has been found that a film having a layer made of a specific resin or resin composition containing hinokitiol or the like is suitable for the above purpose. The present invention was completed based on this knowledge.

That is, the present invention provides linear low-density polyethylene and/or ethylene-vinyl acetate copolymer, or a resin composition containing these as main components, and the addition of hinokitiol, salts thereof, and cyclodextrin clathrate compounds containing them. The present invention provides an antibacterial stretch film for food packaging, which is characterized by containing at least one layer containing one or more of the above compounds.

Preferred hinokitiol, salts thereof, and cyclodextrin clathrate compounds containing them used in the present invention are hinokitiol itself, alkali metal salts of hinokitiol, such as sodium salts and potassium salts, and hinokitiol-cyclodextrin clathrate compounds. Examples include hinokitiol-β-cyclodextrin clathrate compounds. hinokitiol,
The salts and cyclodextrin clathrate compounds containing them (hereinafter referred to as hinokitiols) can be incorporated into stretch films for food packaging to achieve sustained release properties, maintain antibacterial properties, and reduce problems during storage and work. Can be done. However, simply coating the film surface with hinokitiol is not preferable because the hinokitiol exists on the surface and volatilization progresses during storage or operation, and sufficient self-adhesiveness cannot be obtained. moreover,
In the present invention, without impairing the transparency, gloss, and self-adhesiveness necessary for a stretch film for food packaging,
In order to obtain an appropriate sustained release effect of hinokitiol, this hinokitiol is combined with linear low density polyethylene and/or
Alternatively, it is necessary to include it in an ethylene-vinyl acetate copolymer or a resin composition containing these as main components.

[0007] The content of hinokitiol in this case may be appropriately selected depending on various situations, but preferably 0.1 to 5000 mg (in terms of hinokitiol) per 1 m2 of film, more preferably 10 to 2000 mg.
, more preferably 15 to 1000 mg. If this content is too small, the antibacterial effect will not be sufficiently exhibited, while if it is too large, the coloring and odor of the film will deteriorate significantly, which is not practical. Further, the thickness of the stretch film of the present invention is not particularly limited and may be determined as necessary, but is preferably 8 to 30 μm, more preferably 8 to 2 μm.
It is 0 μm. If the thickness of the film is too thin, the strength of the film will be low and there will be problems such as the film being torn after packaging.On the other hand, if the film is too thick, the tray or the packaged object will deform during stretch wrapping, which is undesirable. Furthermore, the thickness of the layer containing hinokitiols also varies depending on the overall thickness of the stretch film and other conditions and cannot be unambiguously determined, but is preferably 1 to 10 μm, more preferably 2 μm.
~6 μm. If the thickness of this layer is too thin, it may be difficult to develop sufficient antibacterial properties. Moreover, if it is too thick, transparency tends to decrease and is not practical.

Furthermore, the stretch film of the present invention only needs to have at least one layer containing hinokitiol, but it is preferable to have it on the food side during packaging, as this will enhance the antibacterial effect. In addition, the layer containing hinokitiol does not necessarily need to be the surface layer of the film because hinokitiol easily evaporates.
In order to improve the basic properties of a stretch film for food packaging such as transparency, gloss, and self-adhesiveness, we added linear low-density polyethylene or ethylene-vinyl acetate copolymer as a surface layer to the layer containing hinokitiol. It is preferable to laminate layers made of , or a resin composition containing these as main components.

The linear low-density polyethylene used in the present invention can be made of various copolymers of ethylene and α-olefin, but usually has a density of 0.860.
~0.910g/cm3, preferably 0.870~0
．． 900 g/cm 3 and a melt flow rate at 190° C. of 0.1 to 10 g/10 minutes, preferably 1 to 5 g/10 minutes. Here, as the α-olefin, for example, 1-propene, 1-butene,
Those having 3 to 12 carbon atoms such as 1-hexene, 1-octene, and 4-methyl-1-pentene are preferred. If the density of linear low-density polyethylene is too low, the strength properties will decrease,
On the other hand, if it is too large, uneven stretching may occur when the film is stretched during packaging, and transparency may be significantly reduced. Furthermore, if the melt flow rate at 190° C. is too small, the productivity of the film will decrease, and if it is too large, there will be a problem that the strength properties and molding stability will decrease.

Furthermore, the ethylene-vinyl acetate copolymer preferably has a vinyl acetate unit content of 5 to 3.
0% by weight, more preferably 5 to 25% by weight, even more preferably 8 to 20% by weight, and the melt flow rate at 190°C is 0.1 to 10 g/10 minutes, more preferably 1 to 5 g/10 minutes. Things can be given. If the vinyl acetate unit content is too small, flexibility, transparency, and deformation recovery properties tend to deteriorate, and if it is too large, strength properties deteriorate. Regarding the melt flow rate at 190° C., if the melt flow rate is too small, not only the elongation properties but also the moldability will be reduced, and if it is too large, the strength properties will be reduced.

In the present invention, in order to adjust flexibility, self-adhesiveness, antifogging properties, etc., various resins and additives can be added to the above-mentioned resin as necessary. . Therefore, in the present invention, linear low-density polyethylene and/or ethylene-vinyl acetate copolymer, or a resin composition containing these as main components, refers to linear low-density polyethylene or ethylene as the main component. −
It refers to a vinyl acetate copolymer containing such various resins, additives, and other auxiliary components as necessary. Ingredients that can be added as needed include:
For example, rubber made of ethylene-propylene copolymer etc. to adjust flexibility, as well as appropriate slipperiness, self-adhesiveness, antifogging properties and antistatic properties, which are basically required properties for stretch films for food packaging. The following additives can be used to impart this. That is, examples of the additive include sorbitan monooleate, sorbitan monolaurate, sorbitan monobehenate, sorbitan monostearate, glycerin monooleate, glycerin monostearate, etc., such as sorbitan fatty acid ester, glycerin fatty acid ester, and polyglycerin fatty acid ester. rate, glycerin monolaurate, glycerin monobehenate, diglycerin monolaurate, diglycerin monostearate, diglycerin monooleate, tetraglycerin monooleate, tetraglycerin monostearate, hexaglycerin monolaurate, hexaglycerin monooleate , decaglycerin monolaurate,
Examples include, but are not limited to, decaglycerin monostearate and decaglycerin monooleate. These fatty acid esters are used alone or as a mixed composition, but the amount added is usually 0.1
It may be appropriately selected within the range of 5.0% by weight, preferably 0.5% to 3.0% by weight.

The stretch film of the present invention may consist of only a layer containing the above-mentioned hinokitiol, but preferably consists of a laminated film in which other layers are laminated. Here, typical examples of other layers to be laminated include various properties required for a stretch film for food packaging, such as tear strength,
This layer provides or improves breaking strength and heat resistance. Specifically, low density polyethylene, ethylene-α
- One or more olefin polymer resins such as olefin copolymer, propylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, crystalline polybutene-1, butene-1-ethylene copolymer, etc. Examples include those consisting of a resin composition. These other layers may have a single layer structure or a multilayer structure combining these layers. By laminating these layers, a multilayer laminated film including a hinokitiol-containing layer can be obtained. In particular, the above-mentioned other olefin polymer resin layer is used as the center layer, and on that side, a layer containing linear low density polyethylene and/or ethylene-vinyl acetate copolymer or hinokitiol containing these as the main component is laminated. A four-layer structure in which a layer containing no hinokitiol is laminated on the other side, and a linear low-density polyethylene and/or an ethylene-vinyl acetate copolymer or a resin composition containing these as main components is laminated on the hinokitiol-containing layer. A film is preferred because it has good transparency, gloss, and self-adhesion.

[0013] The antibacterial stretch film for food packaging of the present invention can be produced by various conventional and well-known methods employed in the production of general laminated films, particularly stretch films for food packaging. . For example, the resin compositions to constitute each layer may be laminated and molded by a known method such as inflation molding using multiple extruders, coextrusion using T-die molding, or extrusion lamination. can. Among these, coextrusion using inflation molding is preferred. Furthermore, the layer containing hinokitiol can be easily made to contain hinokitiol by adding it to the resin during molding. Alternatively, a resin composition containing hinokitiol at a high concentration may be prepared in advance, and the resin composition may be diluted to a desired amount at the time of molding.

[0014]

EXAMPLES Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples. Example 1 Ethylene-vinyl acetate copolymer (vinyl acetate unit content 15% by weight, melt flow rate at 190°C 2.
0g/10min) 80% by weight and polybutene-1 (density 0
．． 915 g/cm3, melt flow rate at 190°C 2.0 g/10 minutes) and linear low density polyethylene (density 0.880 g/cm3).
, melt flow rate at 190°C 3.5g/1
0 min) 98.5% by weight and sorbitan monooleate 1.
5% by weight, and further 98.0% by weight of linear low density polyethylene (density 0.880g/cm3, melt flow rate 3.5g/10 min at 190°C)
, 1.5% by weight of sorbitan monooleate and 0.5% by weight of hinokitiol, each with a caliber of 50
ethylene-vinyl acetate copolymer and polybutene-
The resin temperature was set at 19% so that the composition consisting of 1 was the center layer.
Inflation molding was performed at 0°C with a blow-up ratio of 4.5, and the thickness of each layer was 4 μm/6 μm/4 μm, and the total thickness was 14 μm.
A μm film was obtained. Table 1 shows the evaluation results of this film.

[0015] The physical properties of each item were measured and evaluated in the following manner. 1) Melt flow rate; JIS K72102) Density; JIS K7112; 3) Haze; JIS K6714; 4) Gloss; JIS K7105; It was fixed on a board with tape and then peeled up and down for measurement. 6) Preparation of antibacterial bacterial solution; (Bacillus subtilis) soybean washing solution at 100℃, 10
After heating for 1 minute, the bacteria that grew on a standard agar medium were isolated, and the bacteria presumed to be Bacillus subtilis was cultured on an agar slant (confirmed to be a Gram-positive bacterium). A culture of the bacteria presumed to be Pseudomonas was cultured on an agar slant (confirmed that it is a gram-negative bacterium). Medium: After dispensing 9 ml of standard agar medium into test tubes and sterilizing them,
Store at 5℃. After dispensing 10 ml of potato dextrose agar medium into test tubes and sterilizing them, the tubes are kept at 45°C. Test: (1) Pour 10 ml of medium (standard agar, potato dextrose agar) into a petri dish and solidify. (2) Add 0.1 ml of bacterial solution to (1) and apply with a Conlage stick. (3) Remove the lid of the Petri dish from (2) and package it using the film of Example so that the antibacterial substance-containing layer is on the inside. (4) The Petri dish from (3) was heated to 35°C for Bacillus subtilis and 2°C for psychrotrophic bacteria.
Incubate at 1°C. Evaluation: The presence or absence of growth was compared with the control.

Example 2 Ethylene-vinyl acetate copolymer (vinyl acetate unit content 15% by weight, melt flow rate at 190°C 2.
0g/10min) 60% by weight and polybutene-1 (density 0
．． 908 g/cm3, melt flow rate at 190°C: 1.0 g/10 min) and ethylene-vinyl acetate copolymer (vinyl acetate unit content: 18 wt%, melt flow rate at 190°C: 2.
0g/10 min) and 1.5% by weight of diglycerin monooleate, and further ethylene-
Vinyl acetate copolymer (vinyl acetate unit content 18% by weight)
, melt flow rate at 190°C 2.0g/10
min) 93.5% by weight, diglycerin monooleate 1.5
A composition consisting of % by weight and 5% by weight of hinokitiol,
As in Example 1, each has a diameter of 50 mm and L/D = 26.
Ethylene-
Inflation molding was carried out at a resin temperature of 190°C and a blow-up ratio of 4.5 so that the composition consisting of vinyl acetate copolymer and polybutene-1 formed the center layer, and the thickness of each layer was 4μ.
A film with a total thickness of 14 μm was obtained with m/6 μm/4 μm. Table 1 shows the evaluation results of this film.

Example 3 Ethylene-vinyl acetate copolymer (vinyl acetate unit content 15% by weight, melt flow rate at 190°C 2.
0g/10min) 50% by weight, polybutene-1 (density 0.
908 g/cm
Melt flow rate 1.0g/10min at 30°C)
Composition (a) consisting of 20% by weight and ethylene-vinyl acetate copolymer (vinyl acetate unit content 18% by weight, 190% by weight)
Melt flow rate at °C 2.0 g/10 min) 98
．． 5% by weight and diglycerin monooleate 1.5% by weight
Composition (b) consisting of ethylene-vinyl acetate copolymer (vinyl acetate unit content 18% by weight, melt flow rate 2.0g/10 min at 190°C) 93.5
A composition consisting of 1.5% by weight of diglycerin monooleate and 5% by weight of hinokitiol (c) has a four-layer structure of (b)/(c)/(a)/(b). Extruder 4 each has a diameter of 50 mm and L/D=26.
Inflation molding was performed using a ring-shaped four-layer die using a stand at a resin temperature of 190°C and a blow-up ratio of 4.5, and the thickness of each layer was 2μm/4μm/6μm/6μm/, and the total thickness was 1.
A film of 8 μm was obtained. Table 1 shows the evaluation results of this film.

Comparative Example 1 Ethylene-vinyl acetate copolymer (vinyl acetate unit content 15% by weight, melt flow rate at 190°C 2.
0g/10min) 80% by weight and polybutene-1 (density 0
．． 915 g/cm3, melt flow rate at 190°C 2.0 g/10 minutes) and linear low density polyethylene (density 0.880 g/cm3).
, melt flow rate at 190°C 3.5g/1
0 min) 98.5% by weight and sorbitan monooleate 1.
A composition consisting of 5% by weight was prepared in a tube having a diameter of 50 mm and a L
/D=26 using two extruders and a circular three-layer die,
Inflation molding was carried out at a resin temperature of 190°C and a blow-up ratio of 4.5 so that the composition consisting of ethylene-vinyl acetate copolymer and polybutene-1 formed the center layer, and the thickness of each layer was 4 μm/6 μm/4 μm. A film having a thickness of 14 μm was obtained. Table 1 shows the evaluation results of this film.

Comparative Example 2 Ethylene-vinyl acetate copolymer (vinyl acetate unit content 15% by weight, melt flow rate at 190°C 2.
0g/10min) 80% by weight and polybutene-1 (density 0
．． 915 g/cm3, melt flow rate at 190°C 2.0 g/10 min)
d), linear low density polyethylene (density 0.880g/
cm3, melt flow rate 3.5 at 190℃
Composition (e) consisting of 98.5% by weight of g/10 min) and 1.5% by weight of sorbitan monooleate, and linear low density polyethylene (density 0.880 g/cm
Melt flow rate at °C 3.5 g/10 min) 96
．． A composition (f) consisting of 5% by weight of sorbitan monooleate, 1.5% by weight of sorbitan monooleate and 2% by weight of antibacterial zeolite was prepared using three extruders each having a diameter of 50 mm and L/D=26 to obtain a layer structure of (e )/(d)/(f).
From the layer die, the resin temperature was 190°C and the blow-up ratio was 4.
5, the thickness of each layer is 4μm/6
A film with a total thickness of 14 μm was obtained with μm/4 μm. Table 1 shows the evaluation results of this film.

[0020]

[Table 1]

[0021]

[Effects of the Invention] As described above, the antibacterial stretch film for food packaging of the present invention has excellent antibacterial properties. It also has excellent transparency, gloss, and self-adhesiveness, which are the basic characteristics of a stretch film. It has gloss and self-adhesive properties. Furthermore, since hinokitiol is moderately volatilized from the film, it can exhibit antibacterial properties even if the food does not necessarily come into contact with the film. Therefore, the antibacterial stretch film for food packaging of the present invention can be effectively used for packaging various foods, including fresh foods such as fruits and vegetables, fresh fish, and meat, and has great utility value as a highly practical film.

Claims (5)

[Claims] Claim 1: Linear low-density polyethylene and/or ethylene-vinyl acetate copolymer, or a resin composition containing these as main components, and one of hinokitiol, its salts, and cyclodextrin clathrate compounds containing them. An antibacterial stretch film for food packaging, comprising at least one layer containing the above compound. [Claim 2] The content of one or more compounds selected from hinokitiol, salts thereof, and cyclodextrin clathrate compounds containing them is 0.1 to 500 per m2 of film.
The antibacterial stretch film for food packaging according to claim 1, characterized in that the amount of the antibacterial stretch film is 0 mg (in terms of hinokitiol). 3. The layer containing one or more compounds selected from hinokitiol, salts thereof, and cyclodextrin clathrate compounds containing them has a thickness of 1 to 10 μm. Antibacterial stretch film for food packaging. 4. The linear low density polyethylene according to claim 1, wherein the linear low density polyethylene has a melt fluor rate of 0.1 to 10 g/10 min at 190°C and a density of 0.860 to 0.910 g/cm3. Antibacterial stretch film for food packaging. Claim 5: The ethylene-vinyl acetate copolymer comprises 190
The antibacterial stretch film for food packaging according to claim 1, characterized in that it has a melt fluororate of 0.1 to 10 g/10 min at °C and a vinyl acetate unit content of 5 to 30% by weight.