JP2001163999A - Freshness-keeping film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film suitable as the packaging material having high transparency, glossiness and mechanical strength, and having antibacterial properties and gas permeability which are required for freshness-keeping of contents. SOLUTION: The film comprises at least one layer obtained by processing a resin composition comprising (A) a crystalline propylene polymer and (B) a propylene/α-olefin random copolymer at a ratio [η]B/[η]A of the intrinsic viscosity [η]B of (B) to that [η]A of (A) of 0.3-1.2, and the film is coated or incorporated with an antibacterial agent and the obtained film is constituted to have (1) a water vapor transmission [TH20] of 9-50 (unit: g/m2.24 h), (2) an oxygen gas transmission [T02] of 600-12,500 (unit: nmol/m2.s.100 kP), and (3) an ethylene gas transmission [Tethylene] of 600-22,500 (unit: nmol/m2.s.100 kP).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a film having excellent freshness retention. More specifically, the present invention relates to a film which is excellent in antibacterial performance and mainly allows water vapor, oxygen and ethylene to pass through at an appropriate ratio, respectively, and is suitable as a packaging material for fruits and vegetables.

[0002]

2. Description of the Related Art In recent years, plastic films have been widely used for food packaging, textile packaging and the like. In particular, among the polyolefin films, at least a uniaxially stretched polypropylene film (hereinafter sometimes abbreviated as a stretched PP film) has good transparency, and further has high mechanical strength, so that the printing processability and the like are high. Because of its excellent bag-making workability and filling workability, it is used in many applications as a packaging material.

In general, in a stretched PP film, the regularity of molecular orientation is increased by stretching, and the permeability of a gas such as water vapor or oxygen is reduced due to an increase in the density of the film.
Therefore, when fruits and vegetables are packaged with such a film, the supply of oxygen to the packaged fruits and vegetables from the outside of the packaging material is insufficient, and the freshness is reduced. Also, in the air,
Due to the proliferation of microorganisms attached to the fruits and vegetables which are the packaging, the fruits and vegetables are often spoiled and lose their value as commodities.

[0004] In addition, it is said that fruits and vegetables lose their commercial value if they lose 5% or more of water. Therefore, in order to maintain the freshness, it is also necessary to suppress the amount of moisture that passes through the packaging material and evaporates to the outside of the packaging material from the packaged fruits and vegetables. However, on the other hand, excessive humidification and condensation inside the packaging material also causes spoilage of the packaged fruits and vegetables.

[0005] In addition, if the film used as a packaging material for fruits and vegetables has a low ethylene gas permeability, the ethylene gas generated by the fruits and vegetables themselves accumulates inside the packaging material, causing the fruits to ripen and rot. Problem of promoting

At present, a stretched PP film which is distributed as a packaging material for fruits and vegetables is formed by mixing an anti-fogging agent into the film without properly adjusting the amount of water vapor evaporating from the inside to the outside of the packaging material. Used to prevent gas leakage, or to compensate for gas permeability by physically piercing the film in the process leading to packaging without properly adjusting the amount of water vapor, oxygen, carbon dioxide, etc. It is the fact that it is offered to.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for controlling the permeability of a gas which affects the freshness of a packaged object when used as a packaging material. It is to provide a film, especially a film suitable as a packaging material for fruits and vegetables.
Another object is to provide a film which, when used as a packaging material, can appropriately control the permeability of gas that affects the freshness of a packaged object and has an antibacterial property. In particular, it is to provide a film suitable as a packaging material for fruits and vegetables. Another object is to improve the permeability of water vapor, oxygen, and ethylene gas when used as a packaging material without performing a perforation process which has been conventionally performed. Can be controlled to a value that appropriately maintains and has antibacterial properties,
Further, it is an object of the present invention to provide a film capable of maintaining the excellent transparency, glossiness, and mechanical strength inherent in a PP film, and in particular, to provide a film suitable as a packaging material for fruits and vegetables.

[0008]

Means for Solving the Problems The present inventors have intensively studied to achieve the above object. As a result, it was found that a film obtained by applying or kneading an antibacterial agent using a specific propylene resin composition had good gas permeability and antibacterial performance, and was particularly suitable as a film for fruit and vegetable packaging. The present invention has been completed based on the findings.

That is, the present invention provides a method for producing a crystalline propylene
Copolymer (A) and copolymer having propylene unit content
Professional having a range of 45 to 85% by weight based on the weight of (B).
Contains a pyrene / α-olefin random copolymer (B)
Fewer layers obtained by processing propylene resin composition
A film with a thickness of 10 to 100 μm, including both as one layer
The film is coated or kneaded with an antimicrobial agent.
The propylene resin composition,
The len / α-olefin random copolymer (B) is polymerized
10 to 60 weights based on the total amount of the polymer (A) and the copolymer (B)
% Of propylene / α-olefin
Intrinsic viscosity of the random copolymer (B) [η] _BAnd crystallinity
Intrinsic viscosity [η] of propylene polymer (A)_ARatio [η]_B/
[η]_AIs 0.3 to 1.2, and the obtained film is
(1) Water vapor permeability [T_H2O] (In JISZ 0208)
), (2) Oxygen gas permeability [T₀₂] (JIS K
 7126-A), and (3) ethylene gas
Transmittance [T_ethylene] (Based on JIS K7126-A)
Wherein each has the following values,
It is a freshness retaining film. (1) [T_H2O] = 9 to 50 (unit: g / m^Two・ 24
h) (2) [T₀₂] = 600 to 12500 (unit: nmo)
l / m^Two・ S ・ 100kPa) (3) [T_ethylene] = 600 to 22500 (unit: nm)
ol / m^Two・ S ・ 100kPa)

[0010]

Embodiments of the present invention will be described below. When the film has a water vapor permeability of less than 9 g / m ² · 24 h, when the film is used as a packaging material for fruits and vegetables, the freshness-retaining film of the present invention may cause deterioration of fruits and vegetables due to excessive moisture. Easy to be promoted. On the other hand, the water vapor permeability is 50 g / m ² · 24
If it is larger than h, fruits and vegetables, especially vegetables and the like are dried and tend to wither. The water vapor permeability of the film is 9 to 5
0 g / m ² · 24 h, preferably 10-45 g / m ² ·
The range is 24 h.

The freshness retaining film of the present invention has an oxygen gas permeability of 600 nmol / m ² ···
If the film is less than 100 kPa, when this film is used as a packaging material for fruits and vegetables, the supply of oxygen to the packaged fruits and vegetables from the outside of the packaging material is not sufficiently performed. And its freshness tends to be lost. On the other hand, the oxygen gas permeability is 12,500 nm.
When the pressure is higher than ol / m ² · s · 100 kPa, the water vapor permeability is undesirably too high.
The oxygen gas permeability of the freshness retaining film of the present invention is 600 to 12500 nmol / m ² · s · 100 k.
Pa, especially 1000 to 9000 nmol / m ² · s · 1
It is preferably 00 kPa.

Further, the freshness retaining film of the present invention comprises:
The transmittance of ethylene gas in the film is 600 nm
When it is smaller than ol / m ² · s · 100 kPa, when this film is used as a packaging material for fruits and vegetables, ripening and spoilage of fruits and vegetables are easily promoted. On the other hand, the permeability of the ethylene gas is 22,500 nmol / m ² · s · 100
If the pressure is higher than kPa, the water vapor permeability is undesirably too high. The transmittance of ethylene gas in the freshness retaining film of the present invention is from 600 to 225.
00 nmol / m ² · s · 100 kPa, preferably 6
00 to 15000 nmol / m ² · s · 100 kPa,
Particularly preferred is 600 to 9000 nmol / m ² · s
・ It is 100 kPa.

The freshness retaining film of the present invention has a thickness of 1
It is preferable that the thickness is 0 to 100 μm in terms of film formability, workability (packing property) and the like. 10 film thickness
When the thickness is smaller than μm, it is difficult to form a film having a uniform thickness, and when the thickness is larger than 100 μm, the gas permeability is reduced.

Further, the freshness retaining film of the present invention is coated or kneaded with an antibacterial agent. When the antibacterial agent is kneaded into the film, it is preferable that the antibacterial agent be present in the surface layer of the film as much as possible in order to efficiently exhibit the antibacterial effect.

The crystalline propylene polymer (A) constituting the propylene resin composition used in the present invention is a propylene homopolymer or a propylene polymer containing 90% by weight or more of propylene units based on the weight of the polymer (A). / Α-olefin random copolymer. In particular, the propylene unit is preferably 99.1 to 1 based on the weight of the polymer (A).
A random copolymer of propylene and an α-olefin other than propylene, which is contained in the range of 99.9% by weight, is suitable for use in secondary processing such as multicolor printing and extrusion lamination. When the content of the propylene unit is small, the heat resistance of the obtained film decreases. When the crystalline propylene polymer (A) is a propylene / α-olefin random copolymer, ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, Examples thereof include 1-dodecene, 4-methyl-1-pentene, 3-methyl-1-pentene, and one or more of these are used. Among them, ethylene, 1-butene, or a mixture thereof is preferred from the viewpoint of production cost.

The propylene / α-olefin random copolymer (B) constituting the propylene resin composition used in the present invention contains propylene units in the range of 45 to 85% by weight based on the weight of the copolymer (B). Is a random copolymer of propylene and an α-olefin other than propylene. When the content of the propylene unit is small, the transparency of the obtained film decreases, while when it is large, the gas permeability becomes insufficient. In particular, the propylene / α-olefin random copolymer (B) preferably contains propylene units in the range of 60 to 83% by weight based on the weight of the copolymer (B). Examples of the α-olefin component constituting the propylene / α-olefin random copolymer (B) include the same as the α-olefin component constituting the copolymer (A). In particular, ethylene,
1-Butene or a mixture thereof is preferably used.

The propylene resin composition used in the present invention is
Constituent propylene / α-olefin random copolymer
(B) is the intrinsic viscosity measured in tetralin at 135 ° C.
[η] _BIs preferably 0.5 to 2.0 dl / g.
And more preferably 1.0 to 2.0 dl / g. Step
The electrode of propylene / α-olefin random copolymer (B)
Intrinsic viscosity [η]_BAffects the stiffness and transparency of the film
You. Propylene / α-olefin random copolymer
Intrinsic viscosity [η] of (B)_BThe greater the transparency of the film
Decreases, while if too small, the rigidity of the film decreases.
I do.

The propylene / α-olefin random copolymer (B) is preferably at least 80% by weight, more preferably at least 85% by weight, based on the weight of the copolymer (B). Contains ingredients.

The propylene resin composition used in the present invention comprises:
Propylene / alpha-olefin random copolymer (B) and the intrinsic viscosity [eta] _B of the ratio of the intrinsic viscosity [eta] _A crystalline propylene polymer _{(A) ([η] B} / [η] A) Is 0.3-1.
2, preferably in the range of 0.5 to 1.0. The ratio of intrinsic viscosity ([η] _B / [η] _A ) affects the dispersibility of the propylene / α-olefin random copolymer (B) in the crystalline propylene polymer (A). The ratio of the intrinsic viscosity ([η] _B
/ [Η] _A ) is too large, the transparency of the film decreases,
If it is too small, the rigidity of the film decreases, and the desired properties cannot be achieved.

The intrinsic viscosity of the propylene resin composition used in the present invention is preferably from 1.6 to 3.6 dl / g, and more preferably from 1.8 to 2.5 d, from the viewpoint of moldability during film formation.
1 / g is more preferred.

The propylene resin composition of the present invention comprises the propylene / α-olefin random copolymer (B) in an amount of 10 to 10% based on the total amount of the copolymer (B) and the crystalline propylene polymer (A). 60% by weight, preferably in the range of 15 to 50% by weight.

The film of the present invention obtained by using the propylene resin composition satisfying the constitution specified in the present invention,
In particular, even a single layer has excellent film strength, fusing seal strength, and the like. Further, the film of the present invention has a propylene / α-
The gas permeability can be controlled by adjusting the content of the olefin random copolymer (B) and the stretching ratio of the film. From such a point, the film of the present invention is a film having extremely suitable performance for packaging of fruits and vegetables.

In order to impart gas permeability to a polyolefin film, there has been proposed in the past a method of incorporating a chemical species having a polar group or the like as one component of a composition constituting the film. However, when these different components are added to the polyolefin film, it tends to be an obstacle to cutting the film and recycling it as a polyolefin raw material. Further, when the film is used as a layer component of a laminated film, it is necessary to select a film composed of a component having an affinity for the chemical species having the polar group or the like as another laminated component. The design is also restricted by the multilayer film. The industrial significance of the film of the present invention is extremely high in that it does not require the addition of such a heterogeneous component and has excellent suitability as a film for packaging fruits and vegetables even in a single-layer film.

The antibacterial agent to be contained in the freshness retaining film of the present invention is not particularly limited as long as it is a compound having antibacterial properties, but it is not limited to antibacterial zeolite, far-infrared radiation ceramics or ε-polylysine, or chitosan, hinokitiol or catechin. At least one selected from natural components is preferred. Further, the antibacterial agent contained in the freshness retaining film of the present invention has a particle size characteristic such that the passing amount of a 100-mesh sieve (sieve 150 μm) of JIS-Z8801 (test sieve) is 80% by weight or more. Is preferred. Even more preferred are antibacterial agents having a particle size characteristic such that the passing amount through a 100 mesh sieve (150 μm sieve) is 90% by weight or more. Particularly preferred is an antibacterial agent having a particle size characteristic such that the passing amount through a 200-mesh sieve (75 μm sieve) is 80% by weight or more.

The freshness retaining film of the present invention comprises a propylene / α having a crystalline propylene polymer (A) and a propylene unit content of 45 to 85% by weight based on the weight of the copolymer (B). -Olefin random copolymer (B)
And a film obtained by processing a propylene resin composition containing at least one layer. The film is coated or kneaded with an antimicrobial agent. When the freshness retaining film is a single-layer film, an antibacterial agent is applied to the film at a rate of 0.01 to 300 mg / m ² , or 0.05% based on the weight of the film.
It is kneaded at a rate of about 30% by weight. On the other hand, when the freshness retaining film is a multilayer film, the antibacterial agent is applied to at least one surface layer of the film in an amount of 0.01%.
It is applied at a rate of about 300 mg / m ² or kneaded at a rate of 0.05 to 30% by weight based on the weight of the surface layer.

The amount of the antibacterial agent kneaded into the surface layer of the single-layer film or the multilayer film is 0.1 to 10% by weight based on the weight of the surface layer of the single-layer film or the multilayer film, respectively.
Is more preferable. In each case, if the content of the antibacterial agent is less than 0.05% by weight, the effect of maintaining the freshness cannot be sufficiently obtained, and if it exceeds 30% by weight, the antibacterial agent is not uniformly dispersed because the antibacterial agent is not uniformly dispersed. It is easily damaged, and the antibacterial effect reaches a saturated state.

The amount of the antibacterial agent applied to at least one surface layer of the single-layer film or the multilayer film is 0.5 to 100 mg / m ^{2 based} on the single-layer film or the surface layer.
Is preferable.

The method of kneading the antibacterial agent into the film is not particularly limited. The freshness retaining film of the present invention, when it is a single-layer film, can be produced by mixing the propylene resin composition and the antibacterial agent defined in the present invention, and processing the mixture into a film. . Further, when the freshness retaining film of the present invention is a multilayer film, the antibacterial efficiency is improved when the antibacterial agent is present at a higher concentration in the surface layer of the film. Therefore, the multilayer film is
A propylene resin composition defined in the present invention as a base layer after using a mixture of a propylene resin composition and an antibacterial agent defined in the present invention as a surface layer, or a propylene resin defined in the present invention. It is preferable to use a mixture of a composition other than the composition and an antibacterial agent as the surface layer and then configure the propylene resin composition defined in the present invention as the base layer. The multilayer film production method includes a co-extrusion method, an extrusion lamination method, a dry lamination method, and the like. Although not particularly limited, the co-extrusion method is preferable in terms of cost and the like. Antibacterial agents are generally expensive, and it is preferable in terms of cost to include the antibacterial agent only in the surface layer of the multilayer film.

The method for applying the antibacterial agent to the film is not particularly limited. The antimicrobial agent can be applied to the film by a known method such as a spray method, a roll coater method or a dipping method.

The freshness retaining film of the present invention is preferably a film stretched in at least one direction, in view of the strength of the film. As a stretching method, a sheet formed by a T-die method is drawn by a sequential biaxial drawing method by a tenter method, or a sheet formed by an inflation method is drawn by a simultaneous biaxial drawing method by a tubular method. And the like. The stretching ratio is preferably 3 to 60 times in order to maintain the transparency, strength, and gas passage of the film. If the stretching ratio is less than 3, the thickness of the film tends to be non-uniform, and if it is greater than 60, the film itself tends to be difficult. Preferably,
It is 10 to 60 times, more preferably 20 to 50 times.

In order to impart film strength and straight-cutting properties required as a packaging material, a polypropylene film is usually used after being stretched. Generally, a polypropylene film has a property that the regularity of molecular orientation is increased by stretching and the density of the film is increased, so that a gas such as water vapor or oxygen does not easily pass through the film. However, the film obtained by using the propylene resin composition suitably used in the present invention has a feature that the gas permeation performance does not decrease much even when stretched. In addition, since it has excellent transparency and transparency, the freshness retaining film of the present invention is advantageous when it is necessary to design a thick packaging film according to the requirements of the use environment, especially. Become.

When the freshness retaining film of the present invention is a multilayer film, the thickness of the layer using the propylene resin composition specified in the present invention is 50% based on the thickness of the multilayer film.
The above is preferable for maintaining an appropriate gas permeation amount. If the thickness is less than 50%, the amount of gas permeation tends to be insufficient. In the multilayer film, in addition to the layer obtained by processing the propylene resin composition used in the present invention, as a layer constituting the multilayer film of the present invention, for example, a layer obtained by processing PP, LLDPE, or EVA may be used. Can be illustrated. The method for producing the multilayer film is not particularly limited, and examples thereof include a multilayer extrusion molding method, a dry lamination method, and an extrusion lamination method.

The propylene resin composition used in the present invention comprises:
Any method may be used as long as the above conditions are satisfied, but the production can be suitably performed by employing a multi-stage continuous polymerization method using a gas phase method. This multi-stage continuous polymerization method is a method in which propylene and an olefin other than propylene are copolymerized in the gas phase in the presence of an olefin polymerization catalyst to form a crystalline propylene polymer (A) having a predetermined amount and a predetermined composition. A first polymerization step to be produced, and then a second polymerization step to produce a propylene / α-olefin random copolymer (B) by copolymerizing propylene and an olefin other than propylene while changing their composition ratio, are successively performed in order. It is to implement it. In such a multistage continuous polymerization method, the content of each of the polymer (A) and the copolymer (B) is based on the total amount of the crystalline propylene polymer (A) and the propylene / α-olefin random copolymer (B). The weight% (W _A , W _B ) can be calculated based on, for example, the following equations (1) to (4) by focusing on the components of the catalyst. A calculation example in the case where the catalyst contains Mg as a constituent element is described below. (1) CY _A (g-powder / g-catalyst) = 10000 ×
Mg content in catalyst (wt%) / Mg content in powder extracted in first polymerization step (wtppm) (2) CY _WHOLE (g-powder / g-catalyst) = 1000
0 × Mg content in the catalyst (wt%) / Mg content of the final steps in the extracted in powder _{(wtppm) (3) W B} = (CY WHOLE -CY A) / CY WHOLE (4) W A = 1 −W _B

The intrinsic viscosity [η] _{B of} the propylene / α-olefin random copolymer (B) is also the intrinsic viscosity [η] _{A of the} crystalline propylene polymer (A) directly measured and the final product. Intrinsic viscosity [η] of propylene resin composition
_WHOLE, and it can be found propylene / alpha-olefin random copolymer occupying the propylene resin composition weight percent (B) from (W _B), the following equation (5). (5) [η] _B = ｛[η] _WHOLE − (1−W _B / 100)
_{[η] A} / (W} B / 100)

Further, the propylene / α-olefin random copolymer (B) has a xylene-soluble component weight% (C
XS _B ) is a 20% xylene-soluble component weight% (CXS _A ) of the crystalline propylene polymer (A) and a 20 ° C. xylene-soluble component weight% (CXS) of the propylene resin composition.
_WHOLE), and the propylene / alpha-olefin random copolymer wt% of (B) from (W _B), the following equation (6)
Can be obtained by _{(6) CXS B = {CXS} WHOLE - (1-W B / 100)
_{CXS A} / (W B /} 100)

The olefin polymerization catalyst used in the above production method is not particularly limited, and a known catalyst such as a titanium catalyst or a metallocene catalyst can be used. Among them, a titanium-based catalyst is preferable in terms of cost.

The propylene resin composition used in the present invention may contain known additives such as an antioxidant, an antiblocking agent, an antifogging agent and a surfactant as long as the effects of the present invention are not impaired. it can. As a method of blending the above-mentioned additives with the propylene resin composition, any method can be used as long as they can be uniformly mixed. However, they are mixed with a ribbon blender, a Henschel mixer (trade name) or the like, and the mixture is extruded. It is preferable to use a method in which the mixture is melt-kneaded.

Conventionally, when a film is used as a packaging material for fruits and vegetables, it is necessary to process a hole for allowing gas to pass through the film because the film has insufficient gas permeability. Was. However, with such a film, although the ethylene gas emitted from the inclusions and the oxygen gas necessary for the respiration of the fruits and vegetables are sufficiently absorbed, the emission of water vapor from the fruits and vegetables proceeds at the same time. However, there is a problem that fruits and vegetables are dried and freshness is lost. In addition, there is a serious problem that bacteria enter the hole and cause decay of fruits and vegetables by the bacteria. Further, there is a problem that the film is easily torn from the hole. On the other hand, the freshness-preserving film of the present invention, even without providing a hole, can take in oxygen gas, sufficiently maintain the emission of ethylene gas, and can appropriately suppress the emission of water vapor. The effect of the agent can exert an effect that the freshness of the fruits and vegetables can be maintained for a long time.

The film of the present invention is a film having gas permeability and antibacterial property suitable for packaging of fruits and vegetables, and mainly comprises a copolymer of propylene and an α-olefin other than propylene in the propylene resin composition used. By controlling the content of the combined propylene / α-olefin random copolymer (B), it is possible to adjust the amount of gas passing through the obtained film and the mechanical properties (rigidity, transparency, etc.) of the film. it can.

Further, the freshness retaining film of the present invention comprises:
The ability to omit the conventional process of physically piercing the packaging process results in high productivity and profitability.

In the present specification, "vegetables" refers to vegetables, root vegetables, fruits, flowers, and mushrooms. The following are examples of fruits and vegetables suitable for packaging using the film of the present invention. For example, artichoke, asagi, red beans, asparagus, avocado, aloe, apricot, strawberry,
Fig fruit, iyokan, udo, plum, shallot, edamame, enoki mushroom, okra, olive, orange, kaiware radish, persimmon, turnip, pumpkin, cauliflower, kiwi, chrysanthemum,
Jellyfish, cabbage, cucumber, kumquat, ginkgo, chestnut, green peas, walnut, grapefruit, watercress, gogo, lingonberry, burdock, komatsuna, koriansa, cherry, pomegranate, sweet potato, taro, pomelo, green bean, snow peas, saladana, shiitake mushroom, shiso , Shimeji, potato, shanzei, spring chrysanthemum, ginger, watermelon, sweetie, suzushiro, suzuna, starfruit, zucchini, plum, seri, celery, spring, broad bean, taro, radish, soy, takanotsume, bamboo shoot, onion, taranome,
Bok choy, horsetail, tecopon, winter melon, corn, tomato, durian, truffle, yam, leek,
Eggplant, Nazuna, summer tangerine, rape, nameko, Nagauri,
Japanese pear, chive, carrot, carrot, pineapple, Chinese cabbage, chickweed, parsley, hassaku, banana, papaya, vampire, peppers, loquat, butterbur, fukinotou, kurotake,
Grapes, plums, blueberries, prunes, broccoli, spinach, photokenosa, ponkan, maitake, muscat, mushroom, matsutake, mango, mangosteen, mandarin orange, honeybee, mioga, melon, peach, bean sprouts, moroheiya, yamatoimo, yuzu, pear, mugwort , Lychee, raspberry, radish, apple, lettuce, lemon, lotus root, scallion, wasabi and the like.

[0042]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto. The methods for measuring physical properties and the evaluation criteria shown in the examples and comparative examples are as follows. (1) Transparency: Haze value (unit:%) Measured according to the method described in ASTM D1003. The smaller the value, the better the transparency. (2) Gloss: Gloss (unit:%) Measured according to the method described in ASTM D523.
Larger values indicate higher gloss. (3) Rigidity: Young's modulus (unit: MPa) Measured according to the method described in ASTM D882.
The larger the value, the higher the rigidity of the film. (4) Water vapor permeability: T _H2O (unit: g / m ² · 24)
h) Measured according to the method described in JIS Z-0208.
The measurement was performed under the measurement conditions of a temperature of 40 ° C. and a humidity of 90% RH. (5) Oxygen permeability: T ₀₂ (unit: nmol / m ² · s)
-100 kPa) It measured based on the method of JISK-7126A. (6) Permeability of ethylene gas: T _ethylene (unit: nmol)
/ M ² s · 100 kPa) It was measured according to the method described in JIS K-7126A. (7) Intrinsic viscosity (unit: dl / g) Using a tetralin (tetrahydronaphthalene) as a solvent, an automatic viscosity measurement device (AVS) under a temperature condition of 135 ° C.
The measurement was performed using Model 2 (manufactured by Mitsui Toatsu Co., Ltd.). (8) Amount of xylene-soluble component at 20 ° C. (unit:% by weight) Measured according to the method described in ISO / DIS1873-1. (9) α-Olefin unit content (unit: wt%) It was measured by an infrared absorption spectrum method.

The polymer characteristics of the various propylene resin compositions (PP-1 to PP-3) used in Examples and Comparative Examples are shown below. [PP-1]: A propylene resin composition containing a propylene / α-olefin copolymer (A) and a propylene / α-olefin copolymer (B). Propylene / α-
The olefin copolymer (A) has an α-olefin component of ethylene, contains 99.8% by weight of propylene units based on the weight of the copolymer (A), and has an intrinsic viscosity of 2.2.
3 dl / g. The propylene / α-olefin copolymer (B) has an α-olefin component of ethylene and contains 54% by weight of propylene units based on the weight of the copolymer (B). Further, the copolymer B, the generation amount (W _B) is of 31% by weight, an intrinsic viscosity of 1.49dl
/ G, xylene soluble component at 20 ° C. is 95% by weight. The intrinsic viscosity of the propylene resin composition is 2.00 dl / g. [PP-2]: A propylene homopolymer having an intrinsic viscosity of 2.09 dl / g. [PP-3]: An ethylene / propylene / 1-butene random copolymer having an intrinsic viscosity of 1.83 dl / g and a crystal melting point of 125 ° C.

The PP-1 used in Example 1 was produced as follows. <1> Preparation of Titanium-Containing Solid Catalyst (α) Anhydrous Mg was placed in a nitrogen-purged stainless steel autoclave.
953 g of Cl ₂ and 3.52 liters of dry EtOH were added and the mixture was heated to 105 ° C. with stirring to dissolve. After stirring for 1 hour, pressurized nitrogen heated to 105 ° C. (1.
This solution was sprayed from a two-fluid spray nozzle into the spray tower at 1 MPa). The flow rate of the nitrogen gas was 38 l / min. The inside of the spray tower was maintained at -15 ° C by introducing liquid nitrogen. The composition of the powder (2730 g) collected in the cooled hexane introduced into the bottom of the column was MgC
l was ₂ · 6EtOH.

The resulting powder was sieved to a particle size of 45-2.
2180 g of a 12 μm spherical carrier was obtained. The obtained carrier was washed with nitrogen at a flow rate of 30 L / min at room temperature for 200 hours.
Air drying was performed for a time to obtain a dry carrier having a composition of MgCl ₂ .EtOH. In a stainless steel reactor, purify 1,2-
4.8 liters of dichloroethane, 400 g of a dry carrier, and 3.2 liters of titanium tetrachloride were added, heated to 100 ° C. with stirring, and 0.136 liters of di-i-butyl phthalate was added. After heating, the liquid layer was removed by hot filtration. Purified again to the remaining solid 1,2-
After adding 6.4 liters of dichloroethane and 3.2 liters of titanium tetrachloride and heating at 100 ° C. for 1 hour,
The liquid layer was removed by hot filtration. The obtained solid is washed with purified hexane until no free titanium is detected in the washing liquid, and dried to obtain a titanium-containing solid catalyst (α) containing an average particle diameter of 115 μm and 1.6% by weight of titanium. Obtained.

<2> Preliminary Polymerization of Titanium-Containing Solid Catalyst (α) After replacing the stainless steel reactor (internal volume: 20 liters) with inclined stirring blades with nitrogen gas, the kinematic viscosity at 40 ° C. was 7.
1.7 liters of 3 centistoke saturated hydrocarbon solvent (CRYSTOL-52, manufactured by Esso Oil Co., Ltd.), N-
Hexane 16 liters, triethylaluminum 129
mmol, diisopropyldimethoxysilane 19 mmo
l, and the titanium-containing solid catalyst (α) 1 prepared in the preceding section.
After adding 40 g at room temperature, the mixture was heated to 30 ° C., and 280 g of propylene was supplied over 7 hours to cause a reaction, thereby performing preliminary polymerization. As a result of analysis, 1 g of titanium-containing solid catalyst (α)
1.8 g of polypropylene was produced per unit.

<3> First Polymerization Step A horizontal polymerization vessel having stirring blades (L / D = 6, internal volume 10
0 liter), 0.4 g / hr of the pre-polymerized titanium-containing solid catalyst, triethylaluminum as the organic aluminum compound, and diisopropyldimethoxysilane as the organic silicon compound. 6 was continuously supplied. A mixed gas of ethylene and propylene is reacted at a reaction temperature of 60.
C., a reaction pressure of 2.1 MPa, and a stirring speed of 35 rpm while continuously supplying, and further adjusting the ethylene / propylene molar ratio in the gas phase of the reactor to 0.002 and the hydrogen / propylene molar ratio to 0.008. Then, polymerization was carried out to obtain a propylene / ethylene random copolymer (A).

The obtained propylene / ethylene random copolymer
The polymer (A) has a polymer holding level of 50% of the reaction volume.
Continuously withdrawn from the polymerization vessel in the first polymerization step so that
The solution was fed to the polymerization vessel in the second polymerization step. At this time,
Part of the pyrene / ethylene random copolymer (A) is intermittent
Sampled, ethylene unit content, intrinsic viscosity [η] _A
And the polymer yield per unit weight of catalyst
Was. Polymer yield per unit weight of catalyst
Inductively coupled plasma emission spectroscopy (ICP method)
It was measured.

<4> Second Polymerization Step A horizontal polymerization vessel having stirring blades (L / D = 6, internal volume 10
(0 liter), the propylene / ethylene random copolymer (A) extracted from the first polymerization step and a mixed gas of ethylene and propylene were continuously supplied to copolymerize ethylene and propylene. The reaction conditions are 25r stirring speed.
pm, the temperature was 55 ° C., the pressure was 1.9 MPa, and the gas composition in the gas phase was adjusted to an ethylene / propylene molar ratio of 0.33 and a hydrogen / ethylene molar ratio of 0.54. Carbon monoxide is used as a polymerization activity inhibitor for controlling the polymerization amount of the propylene / ethylene random copolymer (B) thus obtained, and the propylene / ethylene random copolymer (B)
Hydrogen gas for adjusting the molecular weight of was supplied.

The propylene resin composition obtained through the second copolymerization step was continuously withdrawn from the polymerization vessel such that the level of the polymer was 50% by volume of the reaction volume. The production rate of the propylene resin composition was 8 to 15 kg / hr. The extracted propylene resin composition removes unreacted monomers, and partly measures intrinsic viscosity ([η] _WHOLE ),
Of ethylene unit content by infrared and infrared absorption spectrum analysis, and Mg in the composition by ICP method
It was used to determine the propylene / ethylene random copolymer (B) content of the component (W _B) by minute measurement.

Examples 1-4, Comparative Examples 1-2 <Production of Film> Each of PP-1 to PP-3 was
99.4% by weight, based on the weight of the composition obtained by blending, as an antioxidant tetrakis- [methylene-3-
(3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane in a proportion of 0.50% by weight and calcium stearate in a proportion of 0.10% by weight,
Henschel mixer (trade name) uniformly mixed,
The resulting mixture was melt-kneaded with an extruder to obtain pelletized composition-1 to composition-3.

Further, each of PP-1 and PP-3 is
98.4% by weight, based on the weight of the composition obtained by blending, as an antioxidant tetrakis- [methylene-3-
(3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane is added in an amount of 0.50% by weight and calcium stearate in an amount of 0.10% by weight.
1.0% by weight of an antibacterial zeolite whose passing amount through a 100 mesh sieve measured according to IS-Z8801 is 99% by weight and passing amount through a 200 mesh sieve is 98% by weight.
In the mixing ratio of This is called a Henschel mixer
(Trade name), and the resulting mixture was melt-kneaded with an extruder to obtain a pellet composition. The obtained compositions were designated as composition-4 and composition-5, respectively. Further, 98.4% by weight based on the weight of the composition obtained by blending each of PP-1 and PP-3, and tetrakis- [methylene-3- (3 ′, 5 ′) as an antioxidant.
-Di-t-butyl-4'-hydroxyphenyl) propionate] methane in an amount of 0.50% by weight and calcium stearate in an amount of 0.10% by weight.
The amount of passing through a 100 mesh sieve measured according to 01 is 99
Catechin, which was 98% by weight and passed through a 200 mesh sieve, was compounded at a compounding ratio of 1.0% by weight. This was uniformly mixed with a Henschel mixer (trade name), and the obtained mixture was melt-kneaded with an extruder to obtain a pellet-shaped composition. The obtained compositions were designated as composition-6 and composition-7, respectively.

Each of the obtained compositions was used as a raw material for a base layer or a raw material for a surface layer in the combinations shown in Table 1, and the raw materials for the base layer were supplied to an extruder having a diameter of 90 mm, and the raw materials for the surface layer were supplied to an extruder having a diameter of 40 mm. Then, the mixture was co-extruded from a T-die at a melting temperature of 240 ° C., cooled with a cooling roll of 40 ° C.
m, a multilayer sheet consisting of two layers of 70 μm and two types of surface layers was obtained.

Next, the sheet was successively biaxially stretched using a pantograph-type biaxial stretching tester to obtain a biaxially stretched film as shown in Table 1. In Example 1 and Example 2,
After preheating at 156 ° C. for 120 seconds, the film was successively stretched 4.2 times in the machine direction and 8.2 times in the transverse direction at a stretching speed of 10 m / min. In Comparative Examples 1 and 2, 12 ° C. at 160 ° C.
After preheating for 0 seconds, the film was successively stretched by 4.2 times in the machine direction and 8.2 times in the transverse direction at a stretching speed of 10 m / min.

A predetermined test piece was prepared from each of the films thus obtained, and the transparency, rigidity, and gas permeability were measured in accordance with a predetermined test method. Table 1 shows the results.
It was shown to.

[0056]

[Table 1]

<Packaging of Fruits and Vegetables> Using each film, 20 × prepared so that each composition of the surface layer became the inner surface of the bag.
In a 20-cm side fusing seal bag, 50 g of mushrooms are wrapped, and the temperature is 10 ° C and the humidity is 50%.
Table 2 shows an example of observation of the storage state when the storage was performed in the state described above.

[0058]

[Table 2]

Similarly, a 20 × prepared using each film
Table 3 shows observation examples of the storage state when 100 g of beeswax were packaged in a 30 cm side fusing seal bag and stored at a temperature of 10 ° C. and a humidity of 50%.

[0060]

[Table 3]

From the data in Tables 2 and 3, the packaging bag using the film of the present invention (Examples 1 to 4) having good gas permeability is a conventional polypropylene packaging bag (Comparative Examples 1 and 2).
It can be seen that the freshness retention period of the fruits and vegetables has been extended as compared with.

[0062]

The freshness preserving film of the present invention is capable of keeping the intake of oxygen gas and the emission of ethylene gas sufficiently, appropriately suppressing the emission of water vapor, and maintaining the freshness of fruits and vegetables for a long time. It works. Furthermore, it has high transparency, glossiness, and mechanical properties (such as rigidity). Further, the freshness retaining film of the present invention can omit the step of physically forming a hole in the packaging step, and is excellent in productivity and profitability. Therefore, the freshness retaining film of the present invention can be widely used for packaging of fruits and vegetables.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B32B 27/32 103 B32B 27/32 103 B65D 65/40 B65D 65/40 D 81/24 81/24 D 81 / 28 81/28 C 85/50 85/50 C C08J 7/04 C08J 7/04 Z C08K 3/00 C08K 3/00 5/13 5/13 C08L 5/08 C08L 5/08 23/12 23/12 23/14 23/14

Claims (9)

[Claims] 1. A crystalline propylene polymer (A) having a propylene unit content of 45 to 45 based on the weight of the copolymer (B).
A film having a thickness of 10 to 100 μm, comprising at least one layer obtained by processing a propylene resin composition containing the propylene / α-olefin random copolymer (B) in a range of 85% by weight, The film is coated or kneaded with an antibacterial agent, and in the propylene resin composition, the propylene / α-olefin random copolymer (B) comprises the polymer (A) and the copolymer (B).
Respect of the total amount, are contained in a proportion of 10 to 60 wt%, the intrinsic viscosity of the intrinsic viscosity [eta] _B and the crystalline propylene polymer of the propylene / alpha-olefin random copolymer (B) (A) [ η] _A ratio [η] _B / [η] _A is 0.3 ~
1.2, and the obtained film has (1) water vapor permeability [T _H2O ] (based on JIS Z0208) and (2) oxygen gas permeability [T ₀₂ ] (based on JIS K 7126-A) ) And (3) Permeability of ethylene gas [T _ethylene ]
(According to JIS K 7126-A), each having the following value: _{(1) [T H2O] =} 9~50 ( Unit: g / m ² · 24
h) (2) [T ₀₂ ] = 600 to 12500 (unit: nmo)
1 / m ² · s · 100 kPa) (3) [T _ethylene ] = 600 to 22500 (unit: nm)
ol / m ²・ s ・ 100kPa) 2. The crystalline propylene polymer (A) has a propylene unit of 99.1 to 9 based on the weight of the polymer (A).
The freshness retaining film according to claim 1, which is a propylene / α-olefin random copolymer containing 9.9% by weight. 3. The intrinsic viscosity [η] _{B of the} propylene / α-olefin random copolymer (B) is 0.5 to 2.0 dl /.
The freshness retaining film according to claim 1 or 2, which is g. 4. The propylene resin composition, wherein the propylene / α-olefin random copolymer (B) is 15 to 50% by weight based on the total amount of the polymer (A) and the copolymer (B).
The freshness retaining film according to any one of claims 1 to 3, which is contained. 5. The propylene / α-olefin random copolymer (B) contains at least 80% by weight, based on the weight of the copolymer (B), of a xylene-soluble component at 20 ° C.
5. The freshness retaining film according to any one of items 4 to 4. 6. The freshness retaining film according to claim 1, wherein the freshness retaining film is a stretched film stretched in at least a uniaxial direction at a stretching ratio of 3 to 60 times. 7. The freshness preserving film is a single-layer film, and an antibacterial agent is added to the film in an amount of 0.01 to 300.
whether it is applied at a rate of mg / m ^2, or characterized in that it is kneaded in a proportion of 0.05 to 30% by weight, based on the weight of the film, in any one of claims 1 to 6 The freshness retaining film as described in the above. 8. The freshness retaining film is a multilayer film, wherein an antibacterial agent is applied to at least one surface layer of the film at a rate of 0.01 to 300 mg / m ² , or 0.05 to 30 based on the weight of the surface layer
The freshness retaining film according to any one of claims 1 to 6, wherein the film is kneaded at a ratio of weight%. 9. The antimicrobial agent is at least one selected from the group consisting of antimicrobial zeolites, far-infrared radiating ceramics, chitosan, hinokitiol or catechin,
The passing amount of the 100-mesh sieve of the antibacterial agent measured according to JIS Z-8801 is 80% by weight or more based on the weight of the antibacterial agent.
9. The freshness retaining film according to any one of items 8 to 8.