JP2003169598A - Freshness-keeping packaging material and method for freshness-keeping packaging - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a freshness-keeping packaging material forming a film having a uniform gas-permeability, keeping freshness of vegetables and fruits irrespective of their respiration rate. <P>SOLUTION: This freshness-keeping packaging material has 6,500-9,500 cm<SP>3</SP>/ m<SP>2</SP>.day.atm oxygen gas-permeability at 23°C and 80%RH, 23,000-38,000 cm<SP>3</SP>/ m<SP>2</SP>.day.atm carbon dioxide gas-permeability at 23°C and 80%RH and 8-35 g/m<SP>2</SP>.day.atm steam-permeability, wherein the ratio of the carbon dioxide gas- permeability to the oxygen gas-permeability (CO<SB>2</SB>/O<SB>2</SB>) is 3.5-4.1. The packaged body of vegetables or fruits, applied the freshness-keeping packaging material, is provided. The method for freshness-keeping for the vegetables and fruits, enclosing a deoxidant with the vegetables and fruits in packaging the vegetables and fruits is also provided. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packaging material suitable for packaging fruits and vegetables, a packaging body, and a method of maintaining freshness using the packaging material. More specifically, the invention relates to the respiration rate of the fruits and vegetables and the gas permeation rate of the packaging material. The present invention relates to a freshness-retaining packaging material, a packaging body, and a freshness-retaining method capable of maintaining freshness for a long time by adjusting the gas concentration in the atmosphere in which fruits and vegetables are present by maintaining the balance of .

[0002]

2. Description of the Related Art Conventionally, various methods for maintaining freshness of fruits and vegetables have been proposed. Japanese Patent Application Laid-Open No. 61-216640 describes a film having a ratio of carbon dioxide gas permeability and oxygen gas permeability of a certain range. However, it has been found that some fruits and vegetables, such as broccoli, which have a high respiratory rate, may cause anaerobic disorder. Japanese Patent Publication No. 8-2241 discloses a synthetic resin film having a ratio of carbon dioxide gas permeation coefficient to oxygen permeation coefficient and a water vapor permeation coefficient within a certain range. Even if the permeation coefficient of this film is within the above range, the gas permeation amount decreases as the film thickness increases, so that it is presumed that anaerobic disorder is likely to occur and the freshness may be accelerated. Furthermore, the above-mentioned conventional technique is a so-called MA (Modified A) that utilizes the respiration of fruits and vegetables.
Since it takes several days to reach the MA state, it is close to the respiratory state in the air until then, and the so-called CA (gas concentration adjusted from the beginning of the preservation). Controlled atmosphere) The preservation effect may be lower than preservation. Special table 2001-5
No. 04875 discloses a specific density and a specific molecular weight distribution Mw.
/ Mn, a single melting peak as measured by a differential scanning calorimeter, at least one homogeneous linear or substantially linear ethylene polymer having a specific melt index, propylene and optionally ethylene. At least one polypropylene polymer that is a homopolymer or copolymer having a flow rate, and optionally one or more selected from the group consisting of slips, antiblocks, polymer processing aids, antifogs, antistats and roll releases. A non-perforated film structure for use in packaging perishable foods comprising at least one film comprising a blend including additives is described.
Further, in WO99 / 51665, the film thickness,
The invention relates to a single-layer or multi-layer film in which the water vapor permeability, the oxygen gas permeability, and the ethylene gas permeability are regulated within a certain range. This gas permeable film, oxygen gas uptake, after sufficiently maintaining the divergence of ethylene gas, as a result of being able to moderately suppress the divergence of water vapor, it can be said that the freshness of fruits and vegetables can be maintained for a long time. Has been done.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and an object thereof is to maintain freshness from fruits and vegetables having a small respiration rate to fruits and vegetables having a large respiration rate, and a gas of a film. An object is to provide a packaging material having a small variation in transmittance. Another object of the present invention is to provide a method for storing fruits and vegetables which can shorten the time required to reach the MA state.

[0004]

The present inventors have found that a film made of a mixed resin of ethylene-octene copolymer and polypropylene-ethylene copolymer in a specific ratio can solve such a problem, and have found that The invention was completed.

That is, the present invention has an oxygen gas permeability of 6500 to 9500 cm ³ / m ^{2 at} 23 ° C. and 80% RH.
・ The carbon dioxide gas permeability at 23 ° C. and 80% RH is 23,000 to 38,000 cm ³ / m ² at day · atm.
・ Day · atm, the ratio of carbon dioxide gas permeability to oxygen gas permeability (CO ₂ / O ₂ ) is 3.5 to 4.1, and the water vapor permeability is 8 to 35 g / m ^2. day
A freshness-keeping packaging material having an atm is provided. The freshness-keeping packaging material of the invention has a storage elastic modulus of 110 to 1200 MPa. When the storage elastic modulus is E (MPa) and the film thickness is t (μm), E × t ³ is 50 × 10 ³ to 50.
There is provided the freshness-keeping packaging material according to the above invention having a size of × 10 ⁶ .
There is provided a freshness-keeping packaging material of the above invention, which is made of a polyolefin resin. There is provided a freshness-keeping packaging material of the above invention, wherein the polyolefin resin is a blend of 70 to 95% by weight of an ethylene-octene-1 copolymer and 5 to 30% by weight of a propylene-ethylene copolymer. Further provided is the freshness-keeping packaging material of the above-mentioned invention, which comprises an anti-blocking agent, a slip agent, and an antifogging agent. There is provided a freshness-keeping packaging material according to the invention, which is a film, and a freshness-keeping packaging material according to the invention, which is a bag having a sealable opening. The present invention provides a package in which fruits and vegetables are packaged with the freshness keeping packaging material of the above invention.
Also provided is a freshness-keeping method for fruits and vegetables, in which a deoxidizer is enclosed together with the fruits and vegetables when the fruits and vegetables are packed using the freshness-keeping packaging material of the invention.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below.
The freshness-keeping packaging material of the present invention has an oxygen gas permeability of 23 ° C.,
6500-9500 cm ³ / m ² · d at 80% RH
ay · atm, preferably 7800 to 9400 cm ³ /
m ² · day · atm, more preferably 8000 to 93
00 cm ³ / m ² · day · atm, 23 ° C, 80
Carbon dioxide gas permeability at% RH is 23000-3
8000 cm ³ / m ² · day · atm, preferably 28
000 to 37,000 cm ³ / m ² · day · atm, more preferably 29000 to 38,000 cm ³ / m ² · day
· An atm, the ratio of carbon dioxide gas permeability and oxygen gas permeability (CO ₂ / O ₂₎ is from 3.5 to 4.1, preferably 3.6 to 4.0, more preferably 3.8 to It is 4.0. As the material resin that satisfies these requirements, for example,
It can be selected from the following polyolefin resins.
When CO ₂ / O ₂ exceeds 4.1, the CO ₂ concentration in the system decreases, the activity of enzyme activity or the effect of suppressing ethylene production decreases, and the freshness-retaining effect may decrease. If it is less than 3.5, the CO ₂ concentration in the system becomes high, CO ₂ damage may occur, and the freshness may decrease, so it is necessary to be within the specified range.

The packaging material satisfying the above conditions relating to the gas permeability can be selected from various resins or combinations thereof. Examples of those resins include ethylene-butene-1
Ethylene-α-olefin copolymers such as copolymers, ethylene-4-methylpentene-1 copolymers, ethylene-hexene-1 copolymers, ethylene-octene-1 copolymers; high density polyethylene (HDPE) , Polyethylenes such as low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene; polyethylene-based ionomers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-methyl methacrylate copolymers, ethylene- Propylene copolymer, polypropylene, polystyrene, polystyrene-acrylonitrile copolymer, polyurethane, polybutadiene, polyvinyl chloride, styrene butadiene rubber, silicone rubber, polytetrafluoroethylene, polycarbonate, nylon 12, poly 4-
Methyl pentene-1, polysulfone, cellulose triacetate, ethyl cellulose, butyl acetate cellulose, polydimethylsiloxane, polylactic acid, polybutylene succinate-agitate copolymer, polycaprolactone, polyhydroxybutyrate-valerate copolymer, the main components are Examples thereof include a polyester copolymer composed of butanediol, terephthalic acid, adipic acid, and a sulfonate compound, and a polybutylene succinate-carbonate copolymer. The respiration rate of the object to be packaged from these resins, the appearance when formed into a package, the gas permeability of the packaging material, CO ₂ / O ₂
Select as appropriate in consideration of the above.

Further, in the case of packaging fruits and vegetables, in order to prevent the water content of the fruits and vegetables from adhering to the inside of the package in a cloudy state, the water vapor permeability of the packaging material itself is 8 to 35 g / m 2.
² · day · atm, preferably 15 to 28 g / m ² · d
ay · atm, more preferably 18 to 25 g / m ² · d
ay • atm. When these conditions are satisfied, it is possible to obtain a packaging material capable of maintaining freshness from fruits and vegetables having a low respiratory rate to fruits and vegetables having a high respiratory rate. Examples of the packaging material satisfying the water vapor transmission rate include the ethylene-α-olefin copolymer, the polyethylenes, the polyethylene ionomer, the ethylene-vinyl acetate copolymer, the polyvinylidene chloride copolymer, nylon 11 and nylon 12. , Polyethylene terephthalate, polypropylene, poly PE
Nyl sulfide, polyether ether ketone, polytetrafluoroethylene, hydrochloric acid rubber and the like can be mentioned, and it can be selected from those satisfying the conditions of gas permeability and water vapor permeability at the same time. Preferred examples of the resin include a resin mainly containing an ethylene-α-olefin copolymer, and examples of the α-olefin include a copolymer containing 5 to 15% by weight of octene-1, and an ethylene-octene-1 copolymer. (Octene content about 12%)
A blend of 70 to 95% by weight and 5 to 30% by weight of a propylene-ethylene random copolymer (ethylene content of about 3%) can be mentioned. The thickness of the film made of this blend is such that the oxygen gas permeability, the carbon dioxide gas permeability, the ratio of the carbon dioxide gas permeability and the oxygen gas permeability, and the water vapor permeability are within the ranges specified in the present invention. Just set it. The film thickness of the freshness-keeping packaging material of the present invention is not particularly limited, but is practically preferably 20 to 50 μm, more preferably 30 to 45 μm. In addition, a film having a film thickness of 23 μm, which is composed of a resin of 10% by weight of HDPE and 90% by weight of an ethylene-octene-1 copolymer (octene content of about 12% by weight), a propylene-ethylene random copolymer (ethylene content of about 3% by weight). ) A film having a film thickness of 30 μm, which comprises a resin of 20% by weight and 80% by weight of an ethylene-octene-1 copolymer (octene content: about 12% by weight). Since these resins may be processed into a bag after being formed into a film, they preferably have a heat-sealing property capable of ultrasonic sealing and heat sealing. The freshness-keeping packaging material of the present invention may be stretched or unstretched as long as the conditions of the gas permeability and the water vapor permeability are satisfied.

The freshness-keeping packaging material of the present invention has a storage elastic modulus of 11 from the viewpoint of easy handling, appropriate hardness, and hermeticity.
It is preferably 0 to 1200 MPa, more preferably 140 to 250 MPa. When the storage elastic modulus is within this range, it is preferable because it is not too soft and is easy to handle. When the storage elastic modulus is E (MPa) and the film thickness is t (μm), the value of E × t ³ is 5
0 × 10 ³ to 50 × 10 ⁶ , and further 5 × 10 ⁶ to 15 ×
It is preferably 10 ⁶ from the viewpoint of sealing property and handleability. The thickness of the film is not particularly limited, but is usually 20 to 60 μm, preferably 30 to 50 μm. In the present invention, the film thickness can be adjusted in order to adjust the gas permeability to a predetermined level.

The freshness-preserving packaging material of the present invention is a lubricant such as phenol-based, organic sulfur-based, organic nitrogen-based, organic phosphorus-based antioxidants and heat stabilizers, fatty acid derivatives such as metal soap and other fatty acid esters. , Anti-blocking agents, slip agents, anti-fog agents, antistatic agents, calcium carbonate, white carbon, titanium white, magnesium carbonate, magnesium silicate, carbon black, various clays, inorganic fillers such as natural or synthetic zeolites or others 0.5 to 100 parts by weight of the packaging resin, such as a coloring agent of
8 parts by weight can be blended.

The freshness-keeping packaging material of the present invention can be formed into a film by the T-die method or the inflation method. Also, as long as the conditions of the present invention are satisfied, coextrusion with other resins,
Alternatively, it may be a laminate with a resin film. The packaging material can be applied to the packaging of fruits and vegetables in various forms, and the usage form thereof is not particularly limited. A sealable bag or the like is preferably used. The wrapping material of the present invention may wrap fruits and vegetables alone, but in some cases, a freshness-keeping method of enclosing an oxygen scavenger together with the fruits and vegetables may be adopted.

[0012]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited thereto. The methods for measuring physical properties are as follows. 1. Gas permeability sample at 23 ° C and 50% relative humidity (RH) 2
After standing for 4 hours, the oxygen gas permeability at 23 ° C. and 80% RH and the carbon dioxide gas permeability were measured using a film double-sided humidified gas permeation measuring device manufactured by GLS Sciences. 2. Water vapor permeability sample 2 at 23 ℃, 50% relative humidity (RH) atmosphere
After standing for 4 hours, the water vapor transmission rate at 40 ° C. and 90% RH was measured using a water vapor transmission rate measuring device L80-4000 manufactured by LYSSY. 3. Oxygen gas concentration The oxygen gas concentration in the bag was measured using an oxygen concentration meter LC-750 manufactured by Toray Engineering Co., Ltd. 4. Carbon dioxide gas concentration The carbon dioxide gas concentration inside the bag was measured using a gas chromatograph G3800 manufactured by Yanaco. 5. Storage elastic modulus sample 2 in an atmosphere of 23 ° C and 50% relative humidity (RH)
After standing for 4 hours, using a dynamic viscoelasticity measuring device RSAII manufactured by Rheometrics Co., Ltd., a temperature of 20 Hz at a frequency of 10 Hz.
The storage elastic modulus (dynamic elastic modulus) at ° C was measured.

Example 1 Ethylene-octene copolymer (Dow Chemical Japan Ltd., octene content about 12)
%, PL1880) pellets 90% by weight, propylene-ethylene copolymer (Nippon Polychem, EG7F)
10% by weight of pellets of T) are blended, and 2 phr of an anti-blocking agent masterbatch (LDZ50-20, manufactured by Mitsui Chemicals, Inc.) and a slip agent masterbatch (RIKEN Vitamin Co., Ltd., ELM) are added to these resin components.
-080) was added in an amount of 2 phr, and an antifogging agent masterbatch (Riken Vitamin, KP-410) was added in an amount of 3 phr to obtain an unstretched film having a thickness of 45 μm by the T-die method. This film (storage elastic modulus 143 MPa, E × t ³ = 13.0 ×
10 ⁶ ), a 25 cm × 25 cm square bag is prepared by sealing three sides of the square with an impulse sealer, and after putting about 300 g (1 pack) of strawberry, the remaining one side is impulse-sealed. And stored at 5 ° C.

Example 2 A film having a thickness of 35 μm was obtained by the T-die method with the same raw material formulation as in Example 1.
This film (storage elastic modulus 143 MPa, E × t ³ =
With 6.1 × 10 ^6), the size is 25 cm × 25c
Make a square bag with m sides sealed with an impulse sealer on three sides, put about 300 g (1 pack) of strawberry, and then seal the remaining one side with an impulse sealer.
Stored at ° C. Also, one bunch (about 250 g) of broccoli was placed in a bag produced in the same manner, and the remaining one side was sealed with an impulse sealer and stored at 7 ° C.

Example 3 A film having a thickness of 35 μm was obtained by the direct blowing method with the same raw material formulation as in Example 1. This film (storage modulus of 222 MPa, E
Xt ³ = 9.5 × 10 ⁶ ) and the size is 25 cm ×
A 25 cm square bag was prepared in which three sides of the square were sealed with an impulse sealer, about 300 g (1 pack) of strawberry was placed, and the remaining one side was sealed with an impulse sealer and stored at 5 ° C.

COMPARATIVE EXAMPLE 1 Ethylene-octene copolymer (PL1880, Dow Chemical Japan Co., Ltd.) with 2 phr of anti-blocking agent masterbatch (LDZ50-20, manufactured by Mitsui Chemicals, Inc.) and slip agent masterbatch (RIKEN vitamin) Co., Ltd., ELM-080) 2
phr was added, and a film having a thickness of 45 μm was obtained by the T-die method. Using this film, the size is 25 cm x 25 c
Make a square bag with m sides sealed with an impulse sealer on three sides, put about 300 g (1 pack) of strawberry, and then seal the remaining one side with an impulse sealer.
Stored at ° C.

Comparative Example 2 80% by weight of ethylene-octene copolymer (PL1880, Dow Chemical Japan Co., Ltd.), propylene-ethylene random copolymer (Japan Polychem Co., EG7FT, ethylene content about 3%) 2
0 wt% was blended, and 2 phr of an anti-blocking agent masterbatch (LDZ50-20 manufactured by Mitsui Chemicals, Inc.) and 2 of a slip agent masterbatch (RIKEN Vitamin Co., Ltd., ELM-080) were added to these resin components.
phr was added, and an unstretched film having a thickness of 45 μm was obtained by the T-die method. Using this film, the size is 25c
A mx 25 cm square bag was made by sealing the three sides of the square with an impulse sealer, and after putting about 300 g (1 pack) of strawberries, the remaining one side was impulse-sealed to 5
Stored at ° C. A bunch (about 250 g) of broccoli was placed in a bag prepared in the same manner, and the remaining one side was impulse-sealed and stored at 7 ° C.

(Example 4) The same bag as in Example 1 was prepared, and about 300 g (1 pack) of strawberries were added to this bag together with an oxygen scavenger (Ageless SS-100, manufactured by Mitsubishi Gas Chemical Co., Inc.).
Put it in and seal the remaining one side with an impulse sealer, 5
Stored at ° C.

Example 5 The film obtained in Example 1 (storage modulus 143 MPa, E × t ³ = 13.0 × 10 ⁶ ).
Using a square with a size of 25 cm x 25 cm, seal the three sides of the square with an impulse sealer, and
Make a drawstring type that can fit the sides tightly, put a bunch of broccoli (about 250 g), squeeze the opening and stop with a stopper,
As a result of storing at 7 ° C. for 8 days, the oxygen gas concentration inside the bag was at the same level (2.8%) as in Example 2 in which the opening was sealed with an impulse sealer. (Example 6) The film obtained in Example 2 (having a storage elastic modulus of 1
43 MPa, E × t ³ = 6.1 × 10 ⁶ ) was used to prepare a purse bag similar to that used in Example 5, 1 broccoli bag (about 250 g) was placed, the opening was narrowed, and the bag was closed with a stopper. ,
As a result of storage at 7 ° C. for 8 days, the oxygen gas concentration inside the bag was at the same level (3.7%) as in Example 2 in which the opening was sealed with an impulse sealer.

Comparative Example 3 A film made of polypropylene-ethylene copolymer having a thickness of 35 μm (having a storage elastic modulus of 12).
A drawstring bag similar to that of Example 5 was prepared using 50 MPa and E × t ³ = 54 × 10 ⁶ and one broccoli (about 2) was prepared.
50g), squeeze the opening, close with a stopper, and
As a result of storing at 8 ° C. for 8 days, the oxygen gas concentration inside the bag was 21%, which was the same as in air. Examples 1 to 3 and Comparative Example 1
The gas permeability, the gas permeability ratio, and the water vapor permeability of the films obtained in Examples 1 to 2 are shown in Table 1, Examples 1 to 4 and Comparative Examples 1 to 1.
Table 2 shows the changes in the gas concentration inside the package and the appearance in the strawberry packaging test of No. 2. Table 3 shows changes in gas concentration inside the packaging and appearance in the broccoli packaging tests of Example 6 and Comparative Example 2.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

[Table 3]

(Example 7) Table 4 shows changes in gas concentration and appearance in the package when the same bag as in Example 3 was used, the stored product was changed, and the product was stored at a storage temperature of 7 ° C for 7 days. Indicated.

[0025]

[Table 4]

[0026]

EFFECTS OF THE INVENTION According to the present invention, the effect of maintaining freshness is great, and by using an oxygen scavenger together during the packaging of fruits and vegetables, it is possible to shorten the time for the oxygen concentration in the packaging bag to drop, thus maintaining freshness. It has become possible to provide a packaging material that is even more effective.

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08L 23/08 C08L 23/08 4J002 // (C08L 23/08 23:14 23:14) (72) Inventor Shinichiro Funabashi 18-13 Kamitamasato, Tamazato-mura, Shinji-gun, Ibaraki K-ha Chemical Industry Co., Ltd. Resin Processing Technology Center F-term (reference) EA09 EE25 EE32 FC01 GB01 GB13 GD01 GD07 3E086 AB02 AC22 AD01 BA15 BA35 BB02 BB03 BB05 BB14 BB51 BB55 BB58 BB66 CA17 CA18 4B069 AB03 HA01 HA11 KA02 KA08 KB04 KD01 KD06 KD07 KD08 4F071 AA14 AA15 AA20 AF07 AF08 AH04 BA01 BB06 BC01 4J002 BB051 BB142 FD17 FD20 GG02

Claims (10)

[Claims] 1. The oxygen gas permeability at 23 ° C. and 80% RH is 6500 to 9500 cm ³ / m ² · day · atm.
The carbon dioxide gas permeability at 23 ° C. and 80% RH is 23,000 to 38,000 cm ³ / m ² · day · atm.
And the ratio of carbon dioxide gas permeability to oxygen gas permeability (CO ₂ / O ₂ ) is 3.5 to 4.1, and the water vapor permeability is 8 to 35 g / m ² · day · atm. A packaging for keeping freshness. 2. The freshness-keeping packaging material according to claim 1, which has a storage elastic modulus of 110 to 1200 MPa. 3. When the storage elastic modulus is E (MPa) and the film thickness is t (μm), E × t ³ is 50 × 10 ³ to 50 ×.
The freshness-keeping packaging material according to claim 1 or 2, wherein the packaging material is 10 ⁶ . 4. The method according to claim 1, which is made of a polyolefin resin.
The freshness-keeping packaging material according to any one of 1. 5. The freshness-keeping packaging material according to claim 4, wherein the polyolefin resin comprises a blend of 70 to 95% by weight of an ethylene-octene-1 copolymer and 5 to 30% by weight of a propylene-ethylene copolymer. 6. The freshness-keeping packaging material according to claim 5, further comprising an antiblocking agent, a slip agent, and an antifogging agent. 7. The freshness-keeping packaging material according to claim 1, which is a film. 8. The freshness-keeping packaging material according to claim 1, which is a bag having a sealable opening. 9. A package in which fruits and vegetables are packaged with the freshness-retaining packaging material according to any one of claims 1 to 8. 10. A method for maintaining freshness of fruits and vegetables, which comprises encapsulating an oxygen scavenger together with the fruits and vegetables when packaging the fruits and vegetables using the freshness-keeping packaging material according to any one of claims 1 to 8.