JP3162737B2 - Antibacterial stretch film for food packaging - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antibacterial stretch film for food packaging, and more particularly, to transparency, gloss, and the like.
The present invention relates to a stretch film for food packaging having excellent self-adhesiveness and having antibacterial properties.

[0002]

2. Description of the Related Art Stretch wrapping, in which fresh foods such as fruits and vegetables, fresh fish, meat, etc. are placed directly or on a plastic tray and wrapped while stretching a film, has been widely used with the development of supermarkets. Is now widely used as an indispensable packaging method. In recent years, this stretch packaging has taken a step beyond simply improving the product value by the display effect of food, preventing adhesion of various germs, etc. or preventing drying of the packaged item, and maintaining the freshness of the packaged item. It is also required to be done. In such a situation, for example, the viewpoint that freshness of the food can be maintained by sterilizing the packaging film or the container itself and the freshness of the food due to the volatilization of the antibacterial substance from the packaging film or the container itself are reduced. From the viewpoint that it can be maintained,
Suppresses the growth of microorganisms and supplies safe substances to appropriate articles,
For example, a method has been proposed in which various foods are adsorbed on various packaging materials and adhesives and the food is brought into contact with the food surface, or food is coated or packaged with such packaging materials (for example,
JP-A-61-108359, JP-A-2-3024
42, JP-A-2-302451, JP-A-2-302451
JP-A-2747763, JP-A-2-292201, JP-A-3-39363, JP-A-3-4345.
No. 6, JP-A-3-43457, Japanese Patent Application No. 1-3
No. 06734).

On the other hand, in general food packaging, silver, copper,
An antibacterial agent in which metal ions such as zinc, gold, and platinum are supported on an inorganic silicon compound or the like, for example, a film formed by kneading a composition in which an inorganic substance such as an antibacterial zeolite is kneaded with a thermoplastic resin has a large transparency. However, it has been difficult to add an additive amount sufficient to exert a sufficient effect. In particular, in the case of a stretch film for food packaging, properties such as transparency, gloss, and self-adhesiveness are important. However, conventional methods cannot sufficiently satisfy any of the properties and satisfy market requirements. (For example, see JP-A-3-34)
No. 851). As described above, a stretch film for food packaging which has been imparted with antibacterial properties without deteriorating the properties of the conventionally used stretch film for food packaging has not yet been proposed.

[0004]

Means for Solving the Problems Accordingly, the present inventors have:
To solve the above-mentioned problems of the conventional film, research was conducted to develop an antibacterial stretch film for food packaging having excellent transparency, gloss and self-adhesiveness. As a result, they have found that a film having a layer made of a specific resin or a resin composition containing hinokitiol or the like is suitable for the above purpose. The present invention has been completed based on such findings.

That is, the present invention relates to crystalline polypropylene and / or crystalline polybutene-1 or a resin composition containing the same, which contains at least one compound of hinokitiol, a salt thereof, and a cyclodextrin clathrate containing them. Hino comprising at least one of the layers formed as above and comprising a linear low-density polyethylene and / or an ethylene-vinyl acetate copolymer or a resin composition containing these as a main component.
Chithiols, their salts and cyclodextrins containing them
It is intended to provide an antibacterial stretch film for food packaging characterized by laminating at least one layer not containing any of the phosphorus clathrate compounds . The present invention is also directed to a mixture of the above-mentioned crystalline polypropylene and / or crystalline polybutene-1 with an ethylene-vinyl acetate copolymer.

The hinokitiol, salts thereof and cyclodextrin clathrates containing them used in the present invention are preferably hinokitiol itself, alkali metal salts of hinokitiol such as sodium and potassium salts or hinokitiol-cyclodextrin clathrate. And hinokitiol-β-cyclodextrin clathrate. Hinokitiol, its salts and cyclodextrin clathrates containing them (hereafter, hinokitiols) can be sustained-released by incorporating them into stretch films for food packaging, which maintain antibacterial properties and reduce storage and operation problems. can do. However, it is not preferable to simply coat the film surface with hinokitiols, since the hinokitiols are present on the surface, volatilization proceeds during storage and operation, and sufficient self-adhesiveness cannot be obtained. Further, in the present invention, in order to obtain a proper sustained release effect of hinokitiols without impairing the transparency, gloss and self-adhesiveness required as a stretch film for food packaging, the hinokitiols are made of crystalline polypropylene and And / or crystalline polybutene-1 or a resin composition containing them, or an ethylene-vinyl acetate copolymer and crystalline polypropylene and / or crystalline polybutene-
1 or a resin composition containing them.

[0007] The content of hinokitiol such case this may be suitably selected according to various situations, preferably the film 1 m ² per 0.1～5000Mg (hinokitiol basis), more preferably 10～2000Mg, More preferably, it is 15 to 1000 mg. If this content is too small, the antibacterial effect is not sufficiently exhibited, while
If the amount is too large, the coloring and odor of the film are remarkably deteriorated, which is not practical.

[0008] The layer containing hinokitiols is
Any one of crystalline polypropylene and crystalline polybutene-1, or a resin composition containing these, and preferably any one of crystalline polypropylene and crystalline polybutene-1, or a resin composition containing at least 20% by weight of these And more preferably a resin composition containing 20 to 50% by weight, particularly preferably an ethylene-vinyl acetate copolymer and one of crystalline polypropylene and crystalline polybutene-1, or a resin composition comprising these. is there. The reason for specifying the layer containing hinokitiols as described above is that the basic properties of the stretch film for food packaging are tear strength, rupture strength, heat resistance, heat sealing properties, and the horizontal direction with the cutter blade of an automatic packaging machine or by hand. This is for expressing the cutting property for cutting into pieces.

The crystalline polypropylene used in the present invention is a polypropylene produced by a conventionally known method or a copolymer with other resin units. In order to satisfy the basic characteristics as a stretch film for food packaging, a copolymer with ethylene, 1-butene or the like or another α-olefin is preferable, and an ethylene unit content is more preferably 2 to 15% by weight. More preferably 4 to
It is a 12% by weight propylene-ethylene random copolymer. Although there is no particular limitation on its physical properties,
Those having a melt flow rate at 0.1 ° C of 0.1 to 15 g / 10 minutes are preferred. If the ethylene unit content is too small, the flexibility tends to be impaired, while if it is too large, the effect of improving the heat sealability cannot be sufficiently expected. On the other hand, if the melt flow rate is too small, the elongation properties are lowered, and if it is too large, the strength is lowered, which is not preferable.

Next, crystalline polybutene-1 having various physical properties can be used. However, in order to satisfy the basic characteristics as a stretch film for food packaging, the density is 0.8.
90 to 0.920 g / cm ³ , preferably 0.895 to 0.9
The melt flow rate at 190 ° C. is 0.1 to 10 g / 10 min, preferably 1 to 5 g / cm ^3.
It is a butene-1 homopolymer for 10 minutes or a butene-1-ethylene copolymer having an ethylene unit content of 1.5 to 10% by weight. If the density is too low, the effect of improving the cutting properties in the transverse direction of the film is not sufficient, and if it is too high, the flexibility may be reduced. Further, if the melt flow rate is too low, the mixing properties with other resins and the extrudability are not sufficient, and if the melt flow rate exceeds 10 g / 10 minutes, the strength properties may be reduced.

Further, various ethylene-vinyl acetate copolymers can be used, but in order to satisfy the basic properties as a stretch film for food packaging, the content of the vinyl acetate unit is preferably 5 to 25. % By weight, more preferably 8 to 20% by weight, and the melt flow rate at 190 ° C. is 0.1 to 10 g / 10 min, preferably 1 to 10 g / 10 min.
~ 5 g / 10 min. If the vinyl acetate unit content is too small, the flexibility, transparency and deformation recovery properties are liable to decrease, while if it is too large, the strength properties may decrease. Further, when the melt flow rate is too low, not only elongation properties are lowered but also the moldability is lowered, and when it is too high, the strength properties are lowered.

Further, since hinokitiols have the property of being easily volatilized, the layer containing hinokitiols does not need to be a film surface layer, and is a stretch film for food packaging having transparency, gloss, self-adhesiveness and the like. In order to enhance the basic characteristics as a layer containing hinokitiols, a layer composed of a linear low-density polyethylene or ethylene-vinyl acetate copolymer, or a resin composition containing these as a main component, as a surface layer. It is preferable to laminate.

As the linear low-density polyethylene, which is preferable as the surface layer, various copolymers of ethylene and α-olefin can be used, but the density is usually 0.860.
0.909 g / cm ³ , preferably 0.870 to 0.900
g / cm ³ and the melt flow rate at 190 ° C. is 0.1 to 10 g / 10 min, preferably 1 to 5 g / 1.
0 minutes. Here, as the α-olefin, those having 3 to 12 carbon atoms, such as 1-propene, 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene, are preferable. If the density of the linear low-density polyethylene is too low, the strength properties are degraded, and if it is too high, uneven elongation occurs when the film is stretched at the time of packaging, and the transparency may be significantly reduced.
Further, if the melt flow rate at 190 ° C. is too small, the productivity of the film is reduced, and if it is too large, there is a problem that the strength characteristics and the molding stability are reduced.

Further, a preferable ethylene-vinyl acetate copolymer has a vinyl acetate unit content of 5 to 3%.
0 wt%, more preferably 5 to 25 wt%, even more preferably 8 to 20 wt%, and a melt flow rate at 190 ° C of 0.1 to 10 g / 10 min, more preferably 1 to 5 g / 10 min. There are things. If the vinyl acetate unit content is too small, the flexibility, transparency, and deformation recovery properties are liable to decrease, and if it is too large, the strength properties are reduced. If the melt flow rate at 190 ° C. is too small, not only the elongation properties are reduced, but also the moldability is reduced, and if it is too large, the strength properties are reduced.

In the present invention, various resins and additives can be added to the above-mentioned resin as needed in order to adjust flexibility, self-adhesion, anti-fogging property and the like. . Therefore, in the present invention, the resin composition refers to crystalline polypropylene, crystalline polybutene-1 or ethylene-vinyl acetate copolymer as a main component as described above, and further to linear low-density polyethylene, if necessary. Lever refers to those containing various resins, additives and other auxiliary components. Such optional components include, for example, a rubber made of an ethylene-propylene copolymer or the like to adjust flexibility, and a moderate slip property, which is a characteristic basically required as a food packaging stretch film. The following additives can be used for imparting self-adhesiveness, antifogging property and antistatic property. That is, examples of the additive include sorbitan monooleate, sorbitan monolaurate, sorbitan monobehenate, sorbitan monostearate, glycerin monostearate, glycerin monostearate 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 ,
Examples include, but are not limited to, decaglycerin monolaurate, decaglycerin monostearate, decaglycerin monooleate, and the like. These fatty acid esters may be used alone or as a mixed composition. The amount of the fatty acid ester may be appropriately selected in the range of usually 0.1 to 5.0% by weight, preferably 0.5 to 3.0% by weight. I just need.

The stretch film of the present invention comprises a laminated film in which the above-mentioned layer containing hinokitiol and another layer not containing hinokitiol are laminated. That is, the constitution of the present invention is any one of crystalline polypropylene and crystalline polybutene-1 for imparting or improving various characteristics required as a stretch film for food packaging, for example, tear strength, breaking strength, heat resistance. Or a layer of a resin composition containing these, or an ethylene-vinyl acetate copolymer and crystalline polypropylene, crystalline polybutene-1.
Or a layer of a resin composition comprising the same, a hinokitiol is added to the layer, and transparency, gloss, self-adhesiveness, etc. are imparted or improved. / Or ethylene-
Hinokitiol, a salt thereof, and a resin composition comprising a vinyl acetate copolymer or a resin composition containing these as a main component.
Do not contain any cyclodextrin inclusion compound
And at least one of the other layers.

The thickness of the antibacterial stretch film for food packaging of the present invention is not particularly limited and may be determined as needed, but is preferably 8 to 30 μm, and more preferably 8 to 30 μm.
２０20 μm. If the thickness of the film is too thin, the strength of the film will be low and the film will be broken after packaging. On the other hand, if it is too thick, the tray or the article to be packaged will be undesirably deformed during stretch packaging. Furthermore, the thickness of the layer containing hinokitiols also varies depending on the thickness of the entire stretch film and other conditions and cannot be uniquely determined, but is preferably 1 to 10 μm, more preferably 2 to 6 μm. If this layer is too thin, it may be difficult to develop sufficient antibacterial properties. On the other hand, if it is too thick, the transparency tends to decrease, which is not practical. Furthermore, it is sufficient that at least one layer containing hinokitiols is provided.

In producing the antibacterial stretch film for food packaging of the present invention, it can be produced by various known conventional methods employed in the production of general laminated films, especially stretch films for food packaging. . For example, it can be obtained by laminating and molding a resin composition to constitute each layer by a known method such as a co-extrusion method or an extrusion lamination method by inflation molding or T-die molding using a plurality of extruders. it can. Among them, the coextrusion method by inflation molding is preferred. Furthermore, the hinokitiol-containing layer can be easily contained by adding hinokitiol to the resin at the time of molding. Alternatively, a resin composition containing hinokitiols at a high concentration may be prepared in advance, and used after being diluted to a desired amount during molding.

[0019]

Next, the present invention will be described 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. 2.0)
g / 10 minutes) 79.5% by weight, polybutene-1 (density 0.9
15 g / cm ³ , melt flow rate at 190 ° C
2.0 g / 10 min) 20% by weight and hinokitiol in 0.5
% Of the composition and 98.5% by weight of linear low density polyethylene (density 0.880 g / cm ³ , melt flow rate at 190 ° C. 3.5 g / 10 minutes) and 1.5% by weight of sorbitan monooleate. The composition consisting of ethylene-vinyl acetate copolymer, polybutene-1 and hinokitiol becomes the central layer from two annular extruders using two extruders each having a diameter of 50 mm and L / D = 26. As described above, inflation molding was performed at a resin temperature of 190 ° C. and a blow-up ratio of 4.5, and the thickness of each layer was 4 μm / 6 μm /
A film having a thickness of 4 μm and a total thickness of 14 μm was obtained. Table 1 shows the test results of this film.

The measurement and evaluation of the physical properties of each item were carried out by the following methods. 1) Melt flow rate; JIS K7210 2) Density; JIS K7112 3) Haze; JIS K6714 4) Gloss; JIS K7105 5) Self-adhesive; Was fixed to a plate with a tape and peeled up and down for measurement. 6) Preparation of antibacterial bacterial solution; (Bacillus subtilis)
After heating for a minute, the bacteria that grew on the standard agar medium were isolated and cultured on the agar slope (presumed to be Gram-positive bacteria). Pseudomonas putatively isolated and cultured on an agar slope (confirmed to be Gram-negative bacteria) Medium: 9 ml of standard agar medium is dispensed into test tubes in a test tube and sterilized. Keep in a safe place. Potato dextrose agar medium is dispensed into test tubes in 10 ml portions, sterilized, and kept at 45 ° C. Test; (1) 10 ml of medium (standard agar, potato dextrose agar) is poured into a petri dish and solidified. (2) 0.1 ml of the bacterial solution is added to (1), and the mixture is applied with a conical rod. (3) Take off the lid of the Petri dish of (2) and package it using the film of the example so that the antibacterial substance-containing layer is on the inside. (4) The petri dish of (3) is 35 ° C for Bacillus subtilis and 2 for low temperature bacteria.
Incubate at 1 ° C. Evaluation: The presence or absence of growth was compared with the control.

Example 2 Propylene-ethylene random copolymer (content of ethylene unit: 7% by weight, melt flow rate at 230 ° C.)
2.0 g / 10 min) Composition comprising 95 wt% and hinokitiol 5 wt% and ethylene-vinyl acetate copolymer (vinyl acetate unit content 18 wt%, melt flow rate at 190 ° C. 2.0 g / 10 min) A composition consisting of 98.5% by weight and 1.5% by weight of diglycerin monooleate was obtained from an annular three-layer die using two extruders each having a diameter of 50 mm and an L / D = 26 in the same manner as in Example 1. Inflation molding was performed at a resin temperature of 210 ° C. and a blow-up ratio of 4.5 so that the composition comprising the ethylene-vinyl acetate copolymer and diglycerin monooleate became the central layer, and the thickness of each layer was 5 μm / 3 μm / 5 μm. A film having a total thickness of 13 μm was obtained. Table 1 shows the test results of this film.

Example 3 Ethylene-vinyl acetate copolymer (vinyl acetate unit content: 15% by weight, melt flow rate at 190 ° C .: 2.0)
g / 10 min) 50% by weight, polybutene-1 (density 0.90)
8 g / cm ³ , melt flow rate at 190 ° C. 1.
0 g / 10 min) 25 wt%, propylene-ethylene random copolymer (ethylene content 7 wt%, melt flow rate at 230 ° C. 2.0 g / 10 min) 20 wt% and hinokitiol 5 wt% Ethylene-
Vinyl acetate copolymer (vinyl acetate unit content 18% by weight, melt flow rate at 190 ° C 2.0 g / 10
Min.) A composition consisting of 98.5% by weight and 1.5% by weight of diglycerin monooleate was subjected to a circular three-layer die using two extruders each having a diameter of 50 mm and L / D = 26 in the same manner as in Example 1. Inflation molding at a resin temperature of 190 ° C. and a blow-up ratio of 4.5, the thickness of each layer being 4 μm / 6 μm
A film having a thickness of / 4 μm and a total thickness of 14 μm was obtained. Table 1 shows the test results of this film.

Comparative Example 1 Ethylene-vinyl acetate copolymer (vinyl acetate unit content: 15% by weight, melt flow rate at 190 ° C .: 2.0)
g / 10 min) 80% by weight and polybutene-1 (density 0.9
15 g / cm ³ , melt flow rate at 190 ° C
2.0 g / 10 min) composition comprising 20% by weight and linear low density polyethylene (density 0.880 g / cm ³ , 190 ° C.)
The composition comprising 98.5% by weight and 1.5% by weight of sorbitan monooleate was mixed with two extruders each having a diameter of 50 mm and an L / D = 26 to obtain a ring 3 having a melt flow rate of 3.5 g / 10 min. From the layer die, inflation molding was performed at a resin temperature of 190 ° C. and a blow-up ratio of 4.5 so that the composition comprising the ethylene-vinyl acetate copolymer and polybutene-1 became the central layer, and the thickness of each layer was 4 μm / 6 μm.
A film having a thickness of / 4 μm and a total thickness of 14 μm was obtained. Table 1 shows the test results of this film.

Comparative Example 2 Ethylene-vinyl acetate copolymer (vinyl acetate unit content: 15% by weight, melt flow rate at 190 ° C .: 2.0)
g / 10 min) 80% by weight and polybutene-1 (density 0.9
15 g / cm ³ , melt flow rate at 190 ° C
2.0 g / 10 min) Composition (a) consisting of 20% by weight, linear low-density polyethylene (density 0.880 g / cm ³ , 1
Melt flow rate at 90 ° C 3.5 g / 10 min) 9
A composition (b) consisting of 8.5% by weight and 1.5% by weight of sorbitan monooleate, and a linear low-density polyethylene (density 0.880 g / cm ³ , melt flow rate at 190 ° C. 3.5 g / 10 minutes) ) A composition (c) consisting of 96.5% by weight, 1.5% by weight of sorbitan monooleate and 2% by weight of an antibacterial zeolite was prepared by calcining 50 mm in diameter and L / D,
= (B) / (a) / using three extruders of = 26
(C) The resin temperature is set to 19 from the annular three-layer die.
Inflation molding at 0 ° C, blow-up ratio 4.5,
Each layer has a thickness of 4 μm / 6 μm / 4 μm and a total thickness of 14 μm
m was obtained. Table 1 shows the test results of this film.

[0025]

[Table 1]

[0026]

As described above, the antibacterial stretch film for food packaging of the present invention has excellent antibacterial properties. Also, it has excellent transparency, gloss and self-adhesiveness, which are the basic characteristics of a stretch film. For example, compared to a film in which an inorganic substance such as an antibacterial zeolite is kneaded with a thermoplastic resin, excellent transparency, It has gloss and self-adhesiveness. Furthermore, hinokitiols can exhibit antibacterial properties without necessarily contacting the film because they volatilize appropriately from the film. Therefore,
INDUSTRIAL APPLICABILITY The antibacterial stretch film for food packaging of the present invention can be effectively used for packaging various foods such as fresh foods such as fruits and vegetables, fresh fish, meat, etc., and has a great practical value as a highly practical film.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI C08K 5/05 C08K 5/05 C08L 23/12 C08L 23/12 23/20 23/20 // C08L 23:12 23:20 ( 72) Inventor Ritsutaro Fukasawa 4-19-10 Shozuzawa, Itabashi-ku, Tokyo Seiwa Kasei Co., Ltd. (56) References JP-A-61-108359 (JP, A) JP-A 1-245058 (JP, A) JP-A-1-166954 (JP, A) JP-A-58-101133 (JP, A) JP-A-55-81155 (JP, A) JP-A-56-20042 (JP, A) 51537 (JP, A) JP-A-1-135355 (JP, A) JP-A-1-211446 (JP, A) Patent 2849586 (JP, B2) Patent 3068235 (JP, B2) JP-A-8-3277 (JP) , B2) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08J 5/18 CES A23L 3/00 101 B32B 27/18 B32B 27/3 2 B65D 81/24 C08L 23/12 C08L 23/20 CA (STN) REGISTRY (STN)

Claims (5)

(57) [Claims] 1. A layer in which crystalline polypropylene and / or crystalline polybutene-1 or a resin composition containing them contains at least one compound of hinokitiol, a salt thereof, and a cyclodextrin inclusion compound containing them. At least one layer of a linear low-density polyethylene and / or
Alternatively , hinokitiol or a salt thereof comprising an ethylene-vinyl acetate copolymer or a resin composition containing these as a main component
And cyclodextrin inclusion compounds containing them
An antibacterial stretch film for food packaging, characterized by laminating at least one layer containing no displacement . 2. Crystalline polypropylene and / or crystalline
And characterized in that it is a crystalline polypropylene and vinyl acetate copolymer and / or crystalline polybutene-1 or resin compositions containing these - polybutene-1 or resin compositions containing these ethylene <br/> Ren The antibacterial stretch film for food packaging according to claim 1, wherein 3. A layer containing at least one of hinokitiol, a salt thereof and a cyclodextrin inclusion compound containing them, on each of both sides of a layer containing linear low-density polyethylene and / or ethylene-vinyl acetate. Hinokiti comprising a polymer or a resin composition containing these as a main component
Oars, their salts and cyclodextrins containing them
Food packaging antibacterial stretch film according to claim 1 or 2 both of which characterized by being obtained by laminating at least one layer of the layers that do not contain the inclusion compound. 4. The content of one or more of hinokitiol, salts thereof and cyclodextrin clathrates containing them, is 0.1 to 5000 m ² per m ^{2 of} film.
g (in hinokitiol conversion), The antibacterial stretch film for food packaging according to any one of claims 1 to 3. 5. The method according to claim 1, wherein the thickness of the layer containing at least one compound selected from the group consisting of hinokitiol, salts thereof and cyclodextrin clathrates containing them is 1 to 10 μm. The antibacterial stretch film for food packaging according to any one of the above. "