JP7082153B2 - Fruit and vegetable freshness preservation film for automatic packaging and fruit and vegetable freshness preservation packaging bag - Google Patents

Description

The present invention relates to an automatic wrapping film for packaging fruits and vegetables by an automatic wrapping machine, and more particularly to an automatic wrapping fruit and vegetable freshness-preserving film capable of maintaining the freshness of fruits and vegetables as a content.

Fruits and vegetables maintain their vital activity even after harvesting, and oxygenally decompose the sugars and organic acids inside to produce the energy necessary for vital activity. These typical reactions are so-called respiratory reactions that produce carbon dioxide, water, and energy from sugar and oxygen. Since the supply of energy required for the vital activity of fruits and vegetables depends on respiration, the respiratory rate is an important indicator of the physiological activity of fruits and vegetables. When the oxygen concentration in the atmosphere is lowered, breathing is suppressed due to lack of reaction temperament. In addition, when the carbon dioxide concentration is increased, it is considered that respiration is suppressed by the feedback inhibition of the reaction product.

On the other hand, when the oxygen concentration around fruits and vegetables is extremely low, ethanol is produced from pyruvic acid via acetaldehyde by anaerobic respiration, which causes a strong offensive odor and unpleasant taste. Moderate hypoxia and high carbon dioxide conditions are effective in suppressing respiration, while excessive hypoxia or high carbon dioxide conditions can lead to hypoxia and high carbon dioxide disorders.

In this way, fruits and vegetables consume energy by the respiration of the fruits and vegetables themselves during storage and distribution after harvesting, causing a decrease in freshness. If the freshness of fruits and vegetables can be maintained for an extended period of time, it is expected that the amount of waste will be reduced and the consumption area will be expanded by securing distribution time. Demand is rising.

Plastic films are widely used as packaging materials for fruits and vegetables. In particular, the stretched polypropylene film is widely used because it has excellent transparency and gloss, has high mechanical strength, and is excellent in printing processability, bag making processability, and filling workability. In a generally used stretched polypropylene film, the regularity of molecular orientation is increased by stretching, and the density of the film is increased. As the density of the film increases, it becomes difficult for gases such as water vapor and oxygen to permeate. As a result, when the stretched polypropylene film is used for packaging fruits and vegetables, oxygen does not permeate the film and the amount of oxygen required to maintain the freshness of fruits and vegetables is insufficient, and carbon dioxide and ethylene gas emitted by fruits and vegetables are not discharged to the outside. In addition, it may cause a decrease in the freshness of fruits and vegetables.

Therefore, a method has been proposed in which the film is provided with the gas permeability required for the respiration of the fruits and vegetables in order to maintain the freshness of the fruits and vegetables. For example, there is a method of forming fine holes in a film and adjusting the gas permeability of the entire packaging bag according to the size and number of holes (see Patent Document 1). However, this method requires processing to form fine holes in the film in advance, which increases labor and cost and increases the price as a packaging material. In addition, the water generated from the fruits and vegetables in the bag closes the pores of the film, so that the gas permeability becomes unstable and the expected freshness-maintaining effect may not be exhibited.

Further, a method of controlling the gas permeability by laminating a stretched polypropylene film having excellent transparency and a polyethylene film having excellent gas permeability has been proposed (see Patent Document 2). The gas permeability can be adjusted by changing the area and thickness of the polyethylene film. However, there are problems in that it takes time and effort to attach two different types of film base materials, which increases the cost and is not adaptable to an automatic packaging machine.

Further, a gas permeable film for adjusting the gas permeability by blending a copolymer component of ethylene and propylene with a propylene polymer component has been proposed (see Patent Document 3). As the amount of the copolymer component increases, the gas permeability becomes higher, but on the contrary, the rigidity of the film decreases, which may be insufficient for packaging suitability for a pillow packaging machine or the like. Further, if the permeability of the gas is too high, it becomes difficult to maintain a state of low oxygen and high carbon dioxide suitable for maintaining the freshness of fruits and vegetables, and the freshness of fruits and vegetables tends to decrease.

Japanese Patent No. 6358372 Japanese Patent No. 4801104 Japanese Patent No. 3523886

The present invention has been made in view of the above points, and the fruits and vegetables for automatic packaging can be packaged by an automatic packaging machine and have gas permeability suitable for maintaining the freshness of the fruits and vegetables as the contents. It provides a freshness-preserving film.

That is, the first invention is a fruit and vegetable freshness-preserving film for automatic packaging that wraps and manufactures fruits and vegetables by an automatic packaging machine and retains the freshness of the fruits and vegetables as the contents, and heat-seals both surface layers. The polypropylene-based resin composition is composed of three or more co-extruded laminates having a layer having a property, and has a base material layer made of a polypropylene-based resin composition, and is formed by biaxial stretching. Is a polypropylene-based resin composition containing a propylene homopolymer (A) and a copolymer (B) of propylene and at least one α-olefin, and the propylene homopolymer (A) is 3 to 3. The composition is such that the copolymer (B) of 80 parts by weight, the propylene and at least one kind of α-olefin is 20 to 97 parts by weight, and the surface layer on one side of both surface layers of the laminate and others. The temperature difference of the heat seal temperature of each of the surface layers on the side is 5 ° C. or more, the thickness of the fruit and vegetable freshness-preserving film for automatic packaging is 20 to 40 μm, and the oxygen permeability is 2000 to 5500 cm ³ / ( ^m 2.24 hr. -It relates to a fruit and vegetable freshness-preserving film for automatic packaging, which is characterized by being (atm).

The second invention relates to the freshness-preserving film for automatic packaging in which the fruits and vegetables are leaf onions or radishes in the first invention.

The third invention relates to the fruit and vegetable freshness-preserving packaging bag in which the fruit and vegetable freshness-preserving film for automatic packaging is manufactured in the first or second invention.

The fruit and vegetable freshness-preserving film for automatic packaging according to the first invention is a fruit and vegetable freshness-preserving film for automatic packaging that wraps and manufactures fruits and vegetables by an automatic packaging machine and maintains the freshness of the fruits and vegetables as the contents. It is composed of three or more co-extruded laminates having heat-sealable layers on both surface layers, and has a base material layer made of a polypropylene-based resin composition, and is formed by biaxial stretching. The polypropylene-based resin composition is a polypropylene-based resin composition containing a propylene homopolymer (A) and a copolymer (B) of propylene and at least one α-olefin, and the propylene monopoly weight thereof. The composition is such that the coalescence (A) is 3 to 80 parts by weight and the copolymer (B) of the propylene and at least one α-olefin is 20 to 97 parts by weight, and both surface layers of the laminate are formed. The temperature difference between the heat seal temperature of the surface layer on one side and the surface layer on the other side is 5 ° C. or more, the thickness of the fruit and vegetable freshness-preserving film for automatic packaging is 20 to 40 μm, and the oxygen permeability is 2000 to 5500 cm. Since it is ³ / (m ^2.24hr・ atm), it has excellent automatic packaging suitability and antifogging properties, and any gas permeability suitable for maintaining the freshness of fruits and vegetables as its contents, and excellent transparency. It has glossiness, print workability, bag making workability and filling workability.

In the first invention, the fruit and vegetable freshness-preserving film for automatic packaging according to the second invention is intended to maintain freshness by providing gas permeability suitable for leaf onion or radish because the fruit and vegetable are leaf onion or radish. be able to.

In the first or second invention , the third invention is a fruit and vegetable freshness-preserving packaging bag in which a fruit and vegetable freshness-preserving film for automatic packaging is manufactured, so that the freshness of the contents can be maintained.

It is the schematic sectional drawing of the fruit and vegetable freshness preservation film for automatic packaging which concerns on one Embodiment of this invention.

FIG. 1 is a schematic cross-sectional view of a laminate 20 which is a fruit and vegetable freshness-preserving film 10 for automatic packaging according to an embodiment of the present invention. The fruit and vegetable freshness-preserving film 10 for automatic packaging is composed of a laminate 20 obtained by coextrusion of at least three layers of a base material layer 21 and both surface layers 22 and 23. The laminated body 20 is provided with a heat seal layer on the outer surface layer 22 (one side surface layer) and the inner surface layer 23 (the other side surface layer), which are both surface layers of the laminated body 20, and is formed by biaxial stretching. Become. The biaxially stretched film has higher rigidity and is more suitable for packaging by an automatic packaging machine. The fruit and vegetable freshness-preserving film 10 for automatic packaging contains fruits and vegetables as contents inside by an automatic packaging machine, and the inner layers 23 are heat-sealed to form a bag.

The thickness of the fruit and vegetable freshness-preserving film 10 for automatic packaging is 20 to 40 μm. The range is preferable in terms of film moldability, workability at the time of packaging fruits and vegetables, and the like. If the thickness is thinner than 20 μm, it is difficult to make the thickness uniform, the strength of the film decreases and it becomes easy to break the bag when it is put on an automatic packaging machine, or the gas permeability becomes too high, and the effect of keeping the freshness of fruits and vegetables. May not be able to be demonstrated. In addition, the firmness of the film is reduced, and the commercial value of the packaged fruits and vegetables is likely to be reduced. Further, if the thickness of the film is thicker than 40 μm, the permeability of the gas becomes too low, the effect of maintaining freshness is lowered, and the economic efficiency as a packaging material is deteriorated, which is not preferable.

The oxygen permeability of the fruit and vegetable freshness-retaining film 10 for automatic packaging is 2000 to 5500 cm ³ / ( ^m 2.24 hr · atm). Within this range, the amount of oxygen in the packaging bag can be adjusted to maintain the freshness of fruits and vegetables. If the oxygen permeability is lower than 2000 cm ³ / ( ^m 2.24 hr · atm), the respiration of fruits and vegetables becomes insufficient and the freshness tends to decrease. When the oxygen concentration around fruits and vegetables is extremely low, the breathing of fruits and vegetables changes from aerobic breathing to aerobic breathing, and ethanol is accumulated by alcoholic fermentation, causing hypoxic disorders such as causing an offensive odor. If the oxygen permeability of the film is higher than 5500 cm ³ / ( ^m 2.24 hr · atm), the respiration rate of fruits and vegetables may become too fast, and the stored nutrients of fruits and vegetables may be lost and the freshness may be easily lowered. By appropriately controlling the oxygen permeability, the gas permeability of the film can be adjusted, and when used in a packaging bag for fruits and vegetables, the freshness of the fruits and vegetables as the content can be maintained for a long time.

The base material layer 20 is made of a polypropylene-based resin composition, and the propylene-based resin composition is a copolymer of 3 to 80 parts by weight of the propylene homopolymer (A) and propylene and at least one α-olefin. (B) The composition is 20 to 97 parts by weight. When the content of the component (B) is less than 20% by weight, the oxygen permeability becomes low, and the contained fruits and vegetables tend to have insufficient respiration and the freshness tends to decrease. On the other hand, if the amount of the component (B) is too large, the firmness of the film may be lowered, the suitability for automatic packaging may be lowered, or the commerciality of the packaged fruits and vegetables may be lowered.

The method for producing the propylene homopolymer used for the base material layer and the copolymer of propylene and one or more α-olefins is not particularly limited, and is a conventional slurry polymerization method, bulk polymerization method, or gas phase polymerization method. Etc. may be used. For example, "Novatec PP" (registered trademark), "Wintech" (registered trademark), "Newcon" (registered trademark) manufactured by Japan Polypropylene Corporation, "Vistamax" (registered trademark) manufactured by Exxon Mobile Chemical Co., Ltd., Dow. Chemical's "Versify" (registered trademark), Mitsui Chemicals' "Toughmer" (registered trademark), "Toughmer PN", etc. can be mentioned, and can be appropriately selected from these product groups and used alone or in combination. can.

The copolymer (B) of propylene and one or more kinds of α-olefins is selected from a random copolymer obtained by polymerizing propylene and one or more kinds of α-olefins, a block copolymer and the like, and has excellent transparency. Random copolymers are more preferred. Examples of the α-olefin include ethylene, 1-butene, 3-methyl-1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene and the like having 2 carbon atoms. Examples thereof include about 10 α-olefins. From an economic point of view, ethylene and 1-butene are preferably used.

The random copolymer is not particularly limited as long as it is a random copolymer of propylene and one or more kinds of α-olefins, but specifically, for example, a propylene / ethylene random copolymer or a propylene / butene random copolymer. Examples thereof include polymers, propylene / ethylene / butene random copolymers, and the like. Of these, a propylene / ethylene / butene random copolymer is preferably used in order to reduce crystallinity.

Further, the heat seal layers provided on both surface layers of the laminated body are preferably set to have a temperature difference of 5 ° C. or more between the heat seal temperatures. By raising the heat-sealing temperature of the outer layer, the fusion of the heat-sealing layer to the heat-sealing bar of the automatic packaging machine is suppressed, the packaging speed is increased, and the appearance quality of the sealed part is improved. do. The heat seal layer of the outer surface layer is not used for heat seal, but is mainly provided for imparting anti-fog property.

The heat seal layer is a thermoplastic resin layer that is fused during heat seal. The resin material constituting the heat seal layer is not particularly limited as long as it can be fused well, but it is preferable to use a propylene polymer as a main component in consideration of the adhesive strength with the base material layer. From the viewpoint of having heat-sealing properties, it is more preferable to use a propylene-based random copolymer. The random copolymer is not particularly limited as long as it is a random copolymer of propylene and one or more kinds of α-olefins, as in the base layer, but specifically, for example, a propylene / ethylene random copolymer. , Propylene / butene random copolymer, propylene / ethylene / butene random copolymer and the like can be mentioned.

In the fruit and vegetable freshness-preserving film for automatic packaging of the present invention, an antifogging agent, an antistatic agent, and an oxidation agent are applied to the base material layer or both surface layers or both the base material layer and both surface layers as long as the effects of the present invention are not impaired. Known additives such as an inhibitor, a light stabilizer, a lubricant, and an antiblocking agent may be appropriately blended. Among these, from the viewpoint of maintaining the freshness of fruits and vegetables and performing automatic packaging, it is preferable to add an anti-fog agent and an anti-blocking agent.

Examples of the anti-fog agent include three systems of alkyldiethanolamine, alkyldiethanolamine fatty acid ester, and glycerin fatty acid ester, which are conventionally used for anti-fog films. It is used in 1 type or a mixture of 2 to 3 types in 3 types, and among them, the use of 3 types mixed system is preferable.

As the anti-blocking agent, inorganic silica, organic crosslinked acrylic beads and the like are generally used. The anti-fog agent and the anti-blocking agent may be used alone or in combination of two or more.

Further, the surface of the film used for packaging is generally subjected to corona treatment. The same applies to the fruit and vegetable freshness-preserving film for automatic packaging of the present invention. The wetting tension of the film surface due to the corona treatment is preferably 36 mN / m to 44 mN / m. If the wetting tension is less than 36 mN / m, the anti-fog property is not sufficiently exhibited, and the adhesion of the printing ink is poor when printing is performed, which is not preferable. When the wetting tension exceeds 44 mN / m, the anti-fog agent bleeds out to the surface remarkably, causing whitening of the film and blocking phenomenon, which is not preferable.

[Making a freshness-preserving film for fruits and vegetables for automatic packaging]
Regarding the fruits and vegetables freshness-preserving film for automatic packaging of Prototype Examples 1 to 5, based on the resin blending ratio (part by weight) described later, pellets of raw material resin corresponding to the base material layer and both surface layers are supplied to the extruder and supplied. The raw materials were melted and kneaded, and a film was formed by a three-layer coextrusion T-die film forming machine and a subsequent biaxial stretching machine. The stretching ratio was 5 times in the vertical direction (winding direction, MD) and 8 times in the horizontal direction (width direction, TD), and the film was formed by sequential biaxial stretching. After the film formation, both surface layers were subjected to corona treatment.

[Ingredients used]
The following raw materials were used as the resin raw materials for forming the base material layer.
<Ingredient (A)>
-Resin (PP1): Homopolypropylene resin (manufactured by Japan Polypropylene Corporation, "FL203D")
<Ingredient (B)>
-Resin (PP2): Random polypropylene (manufactured by Japan Polypropylene Corporation, "NAH4B")

Next, the following raw materials were used as the resin raw materials forming both surface layers. In addition, the heat seal temperature when each resin is used as a layer is described.
-Resin (PP1): Homopolypropylene resin (manufactured by Japan Polypropylene Corporation, "FL203D"), heat seal temperature 196 ° C.
-Resin (PP3): Random polypropylene (manufactured by Japan Polypropylene Corporation, "FX4E"), heat seal temperature 142 ° C.
-Resin (PP4): Random polypropylene (manufactured by Japan Polypropylene Corporation, "FX4G"), heat seal temperature 132 ° C.

[Prototype example 1]
Of the base material layer, 40 parts by weight of the resin (PP1) was mixed as the component (A) and 60 parts by weight of the resin (PP2) was mixed as the component (B), and the mixture was extruded at 230 ° C. The surface layer was extruded at 200 ° C. using a resin (PP3) on the inside (heat-sealed surface) and extruded at 230 ° C. using a resin (PP1) on the outside. Adjust the discharge amount of each raw material so that the ratio of the thickness of the outer surface layer: the base material layer: the inner surface layer is 1:23: 1 to a thickness of 25 μm, and use the fruit and vegetable freshness-preserving film for automatic packaging of Prototype Example 1. Obtained.

[Prototype example 2]
The same as Prototype Example 1 except that the resin (PP1) of the component (A) of the base material layer was 56 parts by weight and the resin (PP2) of the component (B) was 44 parts by weight, and the fruits and vegetables for automatic packaging of Prototype Example 2 were used. A freshness-preserving film was obtained.

[Prototype example 3]
The same as Prototype Example 1 except that the resin (PP1) of the component (A) of the base material layer was 72 parts by weight and the resin (PP2) of the component (B) was 28 parts by weight, and the fruits and vegetables for automatic packaging of Prototype Example 3 were used. A freshness-preserving film was obtained.

[Prototype example 4]
The base material layer contains 14 parts by weight of the resin (PP1) of the component (A), 86 parts by weight of the resin (PP2) of the component (B), the resin (PP4) is used for the inner layer, and the resin (PP3) is used for the outer layer. ) Was extruded at 200 ° C., and the discharge amount of each raw material was adjusted so that the ratio of the thickness of the outer surface layer: the base material layer: the inner surface layer was 1:28: 1 to a thickness of 30 μm. The freshness-preserving film for fruits and vegetables for automatic packaging of No. 4 was obtained.

[Prototype Example 5]
The same as Prototype Example 1 except that the resin (PP1) of the component (A) of the base material layer was 20 parts by weight and the resin (PP2) of the component (B) was 80 parts by weight, and the fruits and vegetables for automatic packaging of Prototype Example 5 were used. A freshness-preserving film was obtained.

[Freshness retention test 1 (leaf onion)]
Using the films of the above prototype examples 1 to 5 and the following comparative examples 1 and 2, a packaging bag corresponding to each film having a length of 670 mm and a width of 75 mm was prepared, and a freshness retention test was performed on leaf onions. 1 was done. Approximately 100 g (20 to 40) of harvested green onions are stored in each packaging bag, and the openings of the packaging bags of each trial production example and Comparative Examples 1 and 2 except for the packaging bag of Comparative Example 3 below are heat-sealed. Sealed and packaged.

[Comparative Example 1]
-Biaxially stretched polypropylene film (manufactured by Futamura Chemical Co., Ltd., "AF-642S", thickness 25 μm)

[Comparative Example 2]
-Biaxially stretched polypropylene film with micropores (manufactured by Sumitomo Bakelite Co., Ltd., "P-Plus" (for leaf onions), thickness 25 μm)

[Comparative Example 3]
Further, using the same film as in Comparative Example 1, a non-sealed fruit and vegetable freshness-preserving packaging bag in which the openings were sack-wrapped was produced and used as the packaging bag of Comparative Example 3.

Five packaging bags of each prototype and comparative example in which leaf onions were packaged were prepared, and they were stored at 15 ° C., and the freshness of the leaf onions, which were the contents after 4 days and 7 days, was evaluated. As evaluation items, the degree of rising, the degree of leaf tip withering, and the offensive odor at the time of opening were investigated. Similarly, 5 packaging bags for each of the prototypes and comparative examples were prepared, and the chlorophyll content and total sugar content of the leaf onions, which were the contents after 4 days and 7 days, were measured. Further, the oxygen permeability and elastic modulus of the films of Prototype Examples 1 to 5 and Comparative Examples 1 and 2 were measured.

[Evaluation of the degree of rise]
As a physiological reaction after harvesting vegetables, there is hinterland. The hinterland is that the stem of a plant tries to extend in the direction opposite to the gravity, and when fruits and vegetables such as asparagus, leeks, and chrysanthemums are distributed and stored in a laid state, the stems and leaves will rise. As it bends, it causes a loss of commercial value.

Therefore, the degree of rising of the green onions in the contents was visually observed by four evaluators and scored based on the following criteria. For all the leaf onions in the five packaging bags of the prototype example and the comparative example, the average value was calculated and evaluated for the scores evaluated by each evaluator.
0: None (state in which no rise is observed)
1: Slight (although it is slightly recognized, there is no problem with commerciality)
2: Approximately 1/3 of the number of leaves (state that affects commercial value)
3: Approximately 2/3 to almost all leaves of the number of leaves (state that is strongly observed)

[Evaluation of offensive odor at the time of opening]
Similarly, the offensive odor at the time of opening was evaluated by four evaluators, scored based on the following criteria, and the average value was calculated.
0: A state in which no offensive odor is observed 1: A state in which a slight amount is observed but there is no problem in commerciality 2: A condition in which the commerciality is affected 3: A condition in which it is severely observed

[Evaluation of the degree of leaf tip withering]
The degree of leaf tip withering of the contents of the leaf onion was measured, and the length of the wilted part of the leaf tip was measured and scored based on the following criteria.
0: No range of leaf tip withering 1: Leaf tip withering range is 0.1 to 2.5 cm from the tip 2: Leaf tip withering range is 2.6 to 5.0 cm from the tip 3: Leaf tip withering The range is 5.1 to 7.5 cm from the tip 4: The range of leaf tip withering is 7.6 to 10.0 cm from the tip 5: The range of leaf tip withering is 10.1 cm or more from the tip

All leaf green onions in the five packaging bags of each prototype and comparative example were scored, and the index (W) of the packaging bag of each prototype and comparative example was calculated by applying the following formula (i) to the leaf tip. The degree of withering was evaluated. When the index exceeds 10, the leaf tip withered portion begins to stand out, and when the index exceeds 20, it is in a state of withering to the extent that commerciality is not recognized. In formula (i), N ₀ is the number of green onions with 0 points (out of 5 bags), N ₁ is the number of green onions with 1 point, N ₂ is the number of green onions with 2 points, and N ₃ is 3 points. The number of leaf onions is N ₄ , the number of leaf green onions at 4 points, N ₅ is the number of leaf green onions at 5 points, and N is the total number of leaf green onions in 5 bags.

[Measurement of reduction rate of chlorophyll content]
The chlorophyll content is determined by extracting the leaf blade portion of the leaf tip 20 cm with 99.5% ethanol, centrifuging it, and then deciding the volume, and using a spectrophotometer (manufactured by JASCO Corporation, "V-550"). , 750 nm, 665 nm and 649 nm were measured for absorbance. Using the chlorophyll content of leaf green onions at the time of harvest as a reference value, the amount of decrease in chlorophyll content after 4 days and 7 days after storage was calculated as a percentage, and the rate of decrease in chlorophyll content (%) was used. In the table, the reduction rate of chlorophyll content is calculated by calculating the reduction rate of chlorophyll content of 2 leaf onions (10 in total) randomly selected from 5 bags, and 8 values excluding the maximum and minimum values. The average value of the values. Chlorophyll is an essential substance for photosynthesis as a plant, and is an important component for the appearance color of fruits and vegetables contained in chloroplasts. The higher the reduction rate, the lower the chlorophyll content.

[Measurement of reduction rate of total sugar content]
The main sugars contained in fruits and vegetables are glucose, fructose, and sucrose. The sugar contained in fruits and vegetables generally decreases with time after harvesting. Therefore, by measuring the rate of decrease in total sugar content, it was used as an index of the freshness of leaf onions. The root-cut leaf onions were heat-treated with 80% hot ethanol to extract sugar. After the volume was adjusted, hydrochloric acid was added to the extract and hydrolyzed to obtain a reducing sugar solution. After neutralization with sodium hydroxide, it was measured by the Somogi-Nelson method. The total sugar content of the green onions at the time of harvest was used as a reference value, and the amount of decrease in the total sugar content after 4 days and 7 days after storage was calculated as a percentage, and the reduction rate (%) of the total sugar content was used. In the table, the reduction rate of the total sugar content was calculated by calculating the reduction rate of the total sugar content of 2 leaf onions (10 in total) randomly selected from each of the 5 bags, and the maximum value and the minimum value were excluded. It is the average value of the two values.

[Measurement of oxygen permeability]
Next, the oxygen permeability (cm ³ / ( ^m 2.24 hr · atm)) of the films of each prototype and comparative example was measured. The oxygen permeability is a numerical value indicating the permeation amount of oxygen gas, and was measured in accordance with JIS K 7126-1 (2006) (differential pressure method). Since the oxygen permeability of the perforated film cannot be measured by the differential pressure method, the notation in the table is "-".

[Measurement of elastic modulus]
At the same time, the elastic modulus (GPa) of the films of each prototype and comparative example in the vertical direction (winding direction, MD) and the horizontal direction (width direction, TD) was measured in accordance with JIS K 7127 (1999). .. The higher the elastic modulus, the higher the rigidity and the stronger the feeling of elasticity. It was used as an index to evaluate the suitability for packaging by an automatic packaging machine.

Degree of rise of leaf onion, which is the content of the packaging bag of each prototype and comparative example, evaluation of offensive odor at the time of opening, degree of leaf tip withering, reduction rate of chlorophyll content, reduction rate of total sugar content and each prototype The oxygen permeability (cm ³ / ( ^m 2.24 hr · atm)) and elastic modulus (GPa) of the film of the comparative example are shown in Tables 1 and 2.

〔Results and discussion〕
As shown in Tables 1 and 2, the packaging bags of Prototype Examples 1 to 5 maintained the freshness of the green onions better than the packaging bags of Comparative Example 1. Further, the packaging bags of Prototype Examples 1 to 5 are leaf onions even when compared with the packaging bag of Comparative Example 2 using the film having micropores formed and the packaging bag of Comparative Example 3 which is unsealed packaging. The freshness of the was well maintained.

Specifically, in the packaging bags of Prototype Examples 1 to 5, no offensive odor was observed at the time of opening even 7 days after the leaf onions were sealed and packaged and stored at 15 ° C. There was almost no decrease in the appearance freshness of leaf onions and the content of components such as chlorophyll content and total sugar content.

Regarding the degree of rise, in Comparative Example 2 and Comparative Example 3, the degree of rise after 7 days of storage exceeded 1.0, resulting in impaired commercial value. Regarding the offensive odor at the time of opening, in Comparative Example 1 having a low oxygen permeability, an offensive odor at the time of opening was observed 4 days after storage, and the commercial value was impaired. Regarding the degree of leaf tip withering, in Comparative Example 2 and Comparative Example 3, the degree of leaf tip withering after 7 days of storage exceeded 20.0, indicating that the quality of the green onion was significantly deteriorated.

Regarding the reduction rate of the chlorophyll content, in Comparative Example 2 and Comparative Example 3, the reduction rate of the chlorophyll content after 7 days of storage exceeded 20%, and the result was that the appearance freshness of the leaf onion was significantly impaired. Regarding the reduction rate of the total sugar content, in Comparative Example 3, the reduction rate of the total sugar content after 7 days of storage exceeded 20%, which was a result that the freshness of the leaf onion was significantly impaired.

Furthermore, when automatic packaging was performed using an automatic packaging machine (manufactured by Omori Machinery Co., Ltd., "CS-3600X") using Prototype Example 4, automatic packaging of green onions was possible at a speed condition of 52 pieces / minute. Met. From this, other prototype examples having an elastic modulus equal to or higher than that of the prototype example 4 are also suitable for an automatic packaging machine.

From the above, in Prototype Examples 1 to 5, Comparative Example 1 which is a general stretched polypropylene film and has low oxygen permeability, Comparative Example 2 which is a freshness-preserving film having fine pores formed, and an unsealed packaging bag are used. It was revealed that the freshness of the leaf onion could be maintained until 7 days later, which was longer than that of a certain Comparative Example 3.

[Freshness retention test 2 (radish)]
Using the films of Prototype Example 4 above and Comparative Examples 4 and 5 below, packaging bags corresponding to the films having a length of 300 mm and a width of 145 mm were prepared, and a freshness retention test 2 for radishes was performed. rice field. About 80 g (5 pieces) of harvested radishes were contained in the packaging bags of Prototype Example 4 and Comparative Example 5, and the openings of each packaging bag were hermetically sealed and packaged by heat sealing. In the packaging bag of Comparative Example 4, a total of four holes (6 mm in diameter) were formed on the front surface and the back surface, 2 cm from the bottom of the packaging bag and 2 cm from both the left and right sides, and then the radish. Approximately 80 g (5 bottles) was accommodated, and the opening of the packaging bag was heat-sealed to obtain an unsealed package for maintaining the freshness of fruits and vegetables.

[Comparative Example 4]
-Biaxially stretched polypropylene film (manufactured by Futamura Chemical Co., Ltd., "AF-642", thickness 20 μm)

[Comparative Example 5]
-Biaxially stretched polypropylene film with micropores (manufactured by Sumitomo Bakelite Co., Ltd., "P-Plus" (for radishes), thickness 20 μm)

Three packaging bags of Prototype Example 4 and Comparative Examples 4 and 5 in which radishes were packaged were prepared, and they were stored at 10 ° C., 15 ° C. and 20 ° C. Under the conditions of 10 ° C. and 15 ° C., the freshness of the radishes which were the contents after 2 days, 4 days and 7 days was evaluated, and under the conditions of 20 ° C., the freshness of the radishes after 2 days and 4 days was evaluated. As an evaluation item, the offensive odor at the time of opening was investigated, and the chlorophyll value was measured. The evaluation of the offensive odor at the time of opening is the same as the freshness maintenance test 1 in the above-mentioned leaf onion.

[Measurement of chlorophyll level]
The chlorophyll value was measured using a chlorophyll meter ("SPAD-502" manufactured by Konica Minolta Co., Ltd.). The chlorophyll value in the table is a value when the chlorophyll value at the start of storage is 100, and the chlorophyll values of the upper, middle and lower parts of 10 radishes randomly selected from 3 bags are used. Measured and averaged. The chlorophyll value correlates with the chlorophyll content, and the lower the chlorophyll value, the lower the chlorophyll content. The chlorophyll value of 80% or more at the start of storage was set as the limit of commerciality.

Evaluation of offensive odor and chlorophyll value at the time of opening the radish, which is the contents of the packaging bags of Prototype Examples 4 and Comparative Examples 4 and 5, are shown in Tables 3 and 20 for those with a storage temperature of 10 ° C and Tables 4 and 20 for those with a storage temperature of 10 ° C. Table 5 shows the ones at ° C.

〔Results and discussion〕
As shown in Tables 3 to 5, the packaging bag of Prototype Example 4 maintained the freshness of the radish better than the packaging bag of Comparative Example 4. Further, the packaging bag of Prototype Example 4 showed the same freshness-retaining effect as the packaging bag of Comparative Example 5 in which micropores were formed.

Specifically, in the case of the packaging bag of Prototype Example 4, a strange odor at the time of opening even after 7 days of storage at 10 ° C, 4 days after storage at 15 ° C, or 2 days after storage at 20 ° C after hermetically sealed packaging. Almost no decrease in chlorophyll level was observed.

Regarding the chlorophyll value, in Comparative Example 4, the chlorophyll value was less than 80% after 7 days of storage at 10 ° C, 4 days after storage at 15 ° C, and 2 days after storage at 20 ° C, and the appearance freshness of the radish was significantly impaired. It was a result. In Prototype Example 4 and Comparative Example 5, the same results were obtained at both storage temperatures.

From the above, it was shown that in Prototype Example 4, the freshness of the radish can be maintained longer than in Comparative Example 4, which is an unsealed packaging bag in which holes are formed in the stretched polypropylene film. Further, it was clarified that Prototype Example 4 has the same freshness-preserving effect as Comparative Example 5 used as a freshness-preserving film. Compared with the film of Comparative Example 5, the fruit and vegetable freshness-preserving film for automatic packaging according to Prototype Example 4 can maintain the freshness of the content of the radish without forming fine holes in the film. Therefore, it is excellent in economy.

〔summary〕
The fruit and vegetable freshness-preserving film for automatic packaging shown in Prototype Examples 1 to 5 can maintain the freshness of fruits and vegetables for a long time when the fruits and vegetables are packaged by appropriately controlling the oxygen permeability. .. Further, the film has a certain rigidity and is provided with heat seal layers on both surface layers, so that the film is suitable for automatic packaging by an automatic packaging machine. Further, since it has an effect of maintaining the freshness of fruits and vegetables, which are the contents, without forming fine pores and the like, it is excellent in economy when producing a film.

In this evaluation test, the freshness-retaining performance of the fruit and vegetable freshness-preserving film for automatic packaging of the present invention was evaluated for leaf onions and radishes, but the freshness can be maintained by an appropriate low oxygen and high carbon dioxide state. As long as it is a fruit or vegetable, it can be applied without particular limitation.

Since the fruit and vegetable freshness-preserving film for automatic packaging of the present invention has appropriate oxygen permeability, it is possible to maintain the freshness of fruits and vegetables well when packaging the fruits and vegetables as the content, and the film can be used. It is also excellent in productivity and economy because it can be manufactured without the trouble of forming fine pores and attaching different films. Furthermore, if it becomes possible to maintain the freshness of fruits and vegetables, it can be expected to contribute to food loss. Therefore, it is a promising alternative to existing fruit and vegetable packaging films.

10 Freshness-preserving film for fruits and vegetables for automatic packaging 20 Laminated body 21 Base material layer 22 Outer surface layer 23 Inner surface layer

Claims (3)

A fruit and vegetable freshness-preserving film for automatic packaging that wraps and manufactures fruits and vegetables with an automatic wrapping machine and retains the freshness of the fruits and vegetables as the contents.
It is composed of three or more coextruded laminates having heat-sealing layers on both surface layers, and has a base layer made of a polypropylene-based resin composition, and is formed by biaxial stretching.
The polypropylene-based resin composition is a polypropylene-based resin composition containing a propylene homopolymer (A) and a copolymer (B) of propylene and at least one α-olefin, and the propylene homopolymer. (A) has a composition of 3 to 80 parts by weight, and the polymer (B) of the propylene and at least one kind of α-olefin is 20 to 97 parts by weight.
The temperature difference between the heat seal temperature of each of the surface layer on one side and the surface layer on the other side of both surface layers of the laminate is 5 ° C. or more.
The thickness of the fruit and vegetable freshness-preserving film for automatic packaging is 20 to 40 μm, and the thickness is 20 to 40 μm.
A fruit and vegetable freshness-preserving film for automatic packaging characterized by an oxygen permeability of 2000 to 5500 cm ³ / ( ^m 2.24 hr · atm). The freshness-preserving film for automatic packaging according to claim 1 , wherein the fruits and vegetables are green onions or radishes. A fruit and vegetable freshness-preserving packaging bag formed from the fruit and vegetable freshness-preserving film for automatic packaging according to claim 1 or 2 .

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