JPH10330573A - Selectively permeable film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a selectively permeable film which has a low oxygen permeability, has a high carbon dioxide permeability in comparison with the oxygen permeability, and exhibits a carbon dioxide permeability in a certain range even in a low-humidity atmosphere. SOLUTION: This film is prepd. from a compsn. which comprises 50-98 wt.% saponified ethylene-vinyl acetate copolymer (A) having an ethylene unit content of 20-50 mol.% and a degree of saponification of vinyl acetate units of 96 mol.% or higher, 0-45 wt.% polyvinyl alcohol (B) having a degree of saponification of 60-95 mol.%, and at least one compd. (C) having an average mol.wt. of 4,000 or lower, selected from among monomers, oligomers, and polymers of alkylene glycols and hydroxy acids, and in an amt. of 0.1 wt.% or higher but not higher than the saturation solubility based on the sum of the contents of ingredients A and B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a selectively permeable film and a laminated film for packaging water-containing foods using the same.

[0002]

2. Description of the Related Art In recent years, with the diversification of food products, the packaging industry has been demanding an optimum packaging film for food products. For example, natural cheese contains live bacteria for fermentation, and these bacteria generate carbon dioxide gas not only in the aging process but also in the distribution process. Therefore, when such cheese is hermetically packaged using a normal plastic bag, the package expands due to the generation of carbon dioxide gas, causing damage and deterioration of the packaging material and contents. Therefore, a food packaging film having high carbon dioxide gas permeability is required.

[0003] On the other hand, not only cheese but also food packaging materials containing moisture are required to have a property of being hardly permeable to oxygen. Oxygen promotes the growth of mold and oxidizes lipids. A packaging material that easily transmits carbon dioxide and hardly transmits oxygen is a characteristic that is similarly required when storing coffee beans in addition to fermented foods such as cheese and miso. But,
A plastic packaging material having a high carbon dioxide gas permeability almost always has a high oxygen permeability. Therefore, there is a demand for the development of a packaging material having a low oxygen permeability and a high ratio of carbon dioxide gas permeability to oxygen permeability.

As a food packaging film having a relatively small oxygen permeability and a large ratio of the carbon dioxide gas permeability to the oxygen permeability, the present inventors have already made a specific polyvinyl alcohol or alkylene glycol polymer. It has been found that a composition composed of a combined product and a specific saponified ethylene / vinyl acetate copolymer and a laminated film using the composition as an intermediate layer are effective (Japanese Patent No. 2517516). In the present invention, polyvinyl alcohol alone has an excellent oxygen barrier property, but has poor melt extrusion processability. Therefore, the addition of an alkylene glycol polymer to the plasticizer causes a decrease in oxygen barrier property. The oxygen barrier property and the melt extrusion processability were improved by adding a saponified ethylene / vinyl acetate copolymer.

The present inventors also disclose in Japanese Patent Application Laid-Open No. 7-179709 a composition comprising a saponified ethylene / vinyl acetate copolymer, polyvinyl alcohol, polyethylene glycol and a thermoplastic resin having a softening temperature of 130 ° C. or lower. Also shows that the gas has selective gas permeability. However, these selectively permeable films have a problem that oxygen permeability is large.

[0006]

SUMMARY OF THE INVENTION The present invention provides a selectively permeable film having a relatively small oxygen permeability and a large ratio of carbon dioxide gas permeability to oxygen permeability, and a food packaging film using the same. Is to do.

[0007]

According to the present invention, when the saponified ethylene / vinyl acetate copolymer is mainly contained in the composition, the oxygen permeability is relatively small and the carbon dioxide permeability relative to the oxygen permeability is relatively low. Is found to be large.

That is, the gist of the present invention is to provide (1) a saponified ethylene / vinyl acetate copolymer having an ethylene content of 20 to 50 mol% and a saponification degree of a vinyl acetate component of 96 mol% or more.
(2) 0 to 45% by weight of polyvinyl alcohol having a saponification degree of 60 to 95% by mole, and (3) at least one selected from the group consisting of monomers, oligomers and polymers of alkylene glycol and hydroxy acid. And average molecular weight
It is a permselective film of a composition having a solubility of not more than 4,000 and not more than 0.1% by weight and not more than the saturated solubility relative to the sum of the contents of the ethylene / vinyl acetate copolymer and the polyvinyl alcohol. Hereinafter, the present invention will be described in detail.

The resin composition of the present invention comprises (1) a saponified product of an ethylene / vinyl acetate copolymer as a matrix, and (2) a polyvinyl alcohol which may or may not be present. (3) at least one selected from the group of monomers, oligomers and polymers of any of alkylene glycol and hydroxy acid is (1) and (2)
Or a structure usually present in (1) saponified ethylene / vinyl acetate copolymer of the matrix. (3) Any monomer, oligomer or polymer of alkylene glycol and hydroxy acid can be dissolved in either (1) saponified ethylene / vinyl acetate copolymer or (2) polyvinyl alcohol,
At the beginning of molding, even if only one of them is included, the other also oozes out over time, so that the composition of each of the sea and the island may change. However, after a certain period of time after the molding, a steady state is reached.

The saponified ethylene / vinyl acetate copolymer as the first component of the composition of the present invention is mainly used in the composition of the present invention, and is used in the range of 50 to 98% by weight. Below this, the matrix cannot be formed and the oxygen permeability increases. If it exceeds 98% by weight, the carbon dioxide / oxygen permeability ratio becomes small. Therefore,
Saponified ethylene / vinyl acetate copolymer is preferably 55
9494% by weight, more preferably 57-90% by weight.

The saponified ethylene / vinyl acetate copolymer is
If the ethylene content is high, the saturated solubility in at least one type of saponified ethylene-vinyl acetate copolymer selected from monomers, oligomers and polymers of alkylene glycol and hydroxy acid increases, and carbon dioxide gas relative to oxygen permeability Although a material having a large transmittance ratio can be obtained, it is difficult to keep the oxygen permeability of the saponified ethylene / vinyl acetate copolymer low, and the opposite relationship is obtained when the ethylene content is small. On the other hand, when the saponification degree of the vinyl acetate component is low, the oxygen permeability increases.
Therefore, the saponified ethylene / vinyl acetate copolymer is
Its ethylene content is 20 to 50 mol%, preferably 20 to 45 mol%
Mol% is appropriate, and those having a saponification degree of the vinyl acetate component of 96 mol% or more, preferably 98 mol% or more are good.

The second component, polyvinyl alcohol, is used in an amount not exceeding 45% by weight. However, when the degree of saponification decreases, the oxygen permeability of the obtained film increases,
Conversely, when the degree of saponification increases, the saturation solubility of any one of monomers, oligomers, and polymers of alkylene glycol and hydroxy acid in polyvinyl alcohol becomes extremely small, the oxygen permeability is relatively small, and the permeability of carbon dioxide to oxygen permeability is relatively small. There is a relation that the ratio of the degrees becomes small. Further, when the degree of saponification increases, the difference between the melting point and the thermal decomposition temperature, that is, the temperature range in which thermoforming is possible, decreases, and when it exceeds 95 mol%, thermoforming becomes difficult. Therefore, the degree of saponification of polyvinyl alcohol is 60 to 95 mol%, preferably 60 to 95 mol%.
9090 mol%, more preferably 60-80 mol% is used.

Further, polyvinyl alcohol is JIS-K672
The average degree of polymerization measured based on 6 is 300 from the point of strength.
As mentioned above, from the viewpoint of moldability, 3500 or less is preferable, more preferably 400 to 3000, and particularly preferably 500 to 2000.

The polyvinyl alcohol as the second component in the composition of the present invention is not necessarily required, but if polyvinyl alcohol is present to some extent, the saponified ethylene / vinyl acetate copolymer as the first component is relatively reduced. So
The carbon dioxide / oxygen permeability ratio increases. Conversely, if there is too much polyvinyl alcohol, the matrix becomes polyvinyl alcohol, and the oxygen permeability becomes too low to control. Accordingly, polyvinyl alcohol is used in an amount of 0 to 45% by weight, preferably 5 to 40% by weight in the composition.

The alkylene glycol as one of the third components is, for example, ethylene glycol, propylene glycol, 1,2-butanediol, 1,3-butanediol,
Examples thereof include 1,4-butanediol and 2,3-butanediol. Among these, 1,2-butanediol, 1,4
-Butanediol is preferred. The alkylene glycol may be any of a monomer, an oligomer and a polymer,
Typical examples of the polymer include polyethylene glycol, and those having an average molecular weight of 400 or more are preferable. On the other hand, the upper limit of the average molecular weight of polyalkylene glycol is 40
Although it is 00, it is preferably about 2000 or less, more preferably 500 to 1 000, from the viewpoint of obtaining a high ratio of carbon dioxide gas permeability to oxygen gas permeability.

Further, at least one of the monomer, oligomer and polymer of the hydroxy acid as the other component of the third component has an average molecular weight of 4000 or less, preferably 2000 or less. For example, lactic acid and lactic acid ester monomers, oligomers and polymers can be mentioned, and among these, lactic acid monomers are preferable.

At least one selected from the group consisting of alkylene glycol or hydroxy acid monomers, oligomers and polymers is inferior in carbon dioxide gas permeability when the amount used in the composition is too small, and the carbon dioxide / oxygen permeability ratio is low. Is small. In particular, when the content of polyvinyl alcohol is small, it cannot be extruded due to thermal decomposition during molding. Conversely, if it is too large, the amount of the monomer, oligomer, polymer, etc. of the alkylene glycol and hydroxy acid dissipated during molding is large, and bleed out from the film is large. Therefore, at least one selected from the group consisting of alkylene glycolate and hydroxy acid monomers, oligomers and polymers is 0.1% by weight or more in the composition and is saturated with respect to the sum of the contents of the saponified ethylene / vinyl acetate copolymer and polyvinyl alcohol. The solubility is not more than the solubility, preferably not less than 2% by weight, more preferably not less than 4% by weight. The saturated solubility varies depending on the content of the saponified ethylene / vinyl acetate copolymer and polyvinyl alcohol in the composition, and varies depending on the mixing ratio of the saponified ethylene / vinyl acetate copolymer and polyvinyl alcohol. When the amount of saponified ethylene / vinyl acetate copolymer and polyvinyl alcohol is equal, the saturation solubility is around 15% by weight.

The saturation solubility is determined as follows. When the polyvinyl alcohol is in the form of pellets, it is pulverized, and the monomer, oligomer or polymer of the alkylene glycol or the hydroxy acid is added to the mixed powder of the saponified ethylene / vinyl acetate copolymer powder and the polyvinyl alcohol powder in an amount estimated to be the saturation solubility. When the monomer, oligomer or polymer of the alkylene glycol and the hydroxy acid is used alone, it is at room temperature when it is liquid at room temperature, and 30% from its softening point when it is liquid at room temperature.
In the case of mixed use, impregnation is carried out by leaving at a single use temperature for 24 hours at a high temperature. The impregnated material is hot pressed under the conditions of 200 ° C., 100 kgf / cm ² for 2 minutes, and the exuded material is wiped immediately with a paper towel to obtain a pressed sheet. The saturated solubility of the alkylene glycol and the hydroxy acid monomer, oligomer or polymer contained in the press sheet is calculated from the weight of the press sheet.

The composition of the present invention may further comprise at least one selected from the group consisting of a saponified ethylene / vinyl acetate copolymer, polyvinyl alcohol and a monomer, oligomer or polymer of an alkylene glycol and a hydroxy acid. As long as the effects of the present invention are not impaired, general-purpose stabilizers, antiblocking agents, lubricants, coloring agents, fillers, and the like can be contained.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The method of mixing the resin constituting the composition of the present invention is not particularly limited, but at least one selected from the group consisting of monomers, oligomers and polymers of alkylene glycol and hydroxy acid. When the content of one type is less than the saturation solubility of either the ethylene / vinyl acetate copolymer and polyvinyl alcohol, they are mixed to dissolve in the resin, and when the content exceeds the saturation solubility of either resin, both resins are mixed. And a method of mixing them so as to be dissolved in any resin so as to have a saturation solubility or less. Among them, alkylene glycol or hydroxy acid is a polymer, and when the polymer has a high molecular weight, it is a solid, so it is dry-blended at 100 to 120 ° C. together with polyvinyl alcohol powder or pellets of saponified ethylene / vinyl acetate copolymer. A method of supplying from a hopper of an extruder, melt-kneading, and pelletizing is suitably adopted. When at least one selected from the group consisting of monomers, oligomers and polymers of alkylene glycol and hydroxy acid is liquid, powder of polyvinyl alcohol or pellets of saponified ethylene / vinyl acetate copolymer is supplied from the hopper of the extruder. A method is preferably employed in which at least one selected from the group consisting of monomers, oligomers and polymers of alkylene glycol and hydroxy acid is supplied from a position in the middle of the extruder, melt-kneaded, and pelletized. The resulting pellets are formed into films, sheets, etc.
It is used alone or laminated with another film, but the film itself may be unstretched or stretched.

The formation of the film comprising the composition of the present invention is as follows.
It is performed by a laminating method, a co-extrusion laminating method, a co-extrusion inflation method or the like. As the stretching of the film, uniaxial stretching or biaxial stretching by an inflation method, a tenter method or the like can be usually adopted. The stretching heating temperature is 85 to 95 ° C, and the stretching ratio is usually 2 in both the vertical and horizontal directions.
~ 4 times. As a heating method at the time of stretching, a hot water bath method, a dry heat method, or the like can be adopted.

The film comprising the composition of the present invention has a high transmission ratio of carbon dioxide to oxygen gas, and is suitable for packaging foods that generate carbon dioxide, such as fresh foods such as fruits and vegetables, cheese, garlic, kimchi, and yam. If cheese is particularly mentioned, it can be used in each stage of the ripening stage and the distribution stage of cheese.

The film made of the composition of the present invention has a low carbon dioxide gas permeability unless it contains a certain amount of water.
That is, when the equilibrium absorptivity described below is less than 5% by weight, the film made of the composition of the present invention has low carbon dioxide gas permeability, and cannot sufficiently transmit carbon dioxide gas. The above-mentioned equilibrium water absorption indicates the water absorption of the film as a percentage with respect to the weight of the film in a dry state. When the equilibrium water absorption is less than 5% by weight, the relative humidity of the outside air, for example, under 20% humidity Happens when is low.

When the film of the composition of the present invention is used as a film for packaging a product containing water such as a water-containing food, the equilibrium water absorption of the film of the composition of the present invention is inevitable as long as the film contains water. Therefore, the permeability of carbon dioxide to oxygen is high even when the film is used alone. However, the film of the composition of the present invention can be used alone or in a laminated configuration as long as it does not come into contact with water in this way, but it has difficulty in retaining water, so that it is in contact with water-containing materials. Single use is not appropriate. When used in contact with water, water can be retained for a long period of time by laminating a resin film having low water permeability on a layer on the side in contact with moisture.

Using the film of the composition of the present invention as an intermediate layer, the water vapor permeability (W ₀ ) of the outer layer (40 ° C., 90% humidity) and the water vapor permeability (W ₁ ) of the inner layer (40 ° C., 90% humidity) ) Is

[0026]

[Equation 1] W ₀ <50 g · m ⁻² · 24hr ⁻¹ W ₀ ≦ W ₁

The multilayer laminated film represented by the following formula (1) is preferably used for packaging food containing water, more preferably

[0028]

[Number 2] is ^{_{W 0 <45g · m -2 ·}} 24hr -1 W 0 ≦ W 1/2, more preferably

[0029]

Equation 3] W ₀ <intended ^{40g · m -2 · 24hr -1 W} 0 ≦ W 1/3 is used. By having such an outer layer and an inner layer, the equilibrium water absorption of the intermediate layer is maintained at a certain level over a long period of time regardless of the relative humidity of the outside air.
The carbon dioxide gas permeability of the intermediate layer is maintained without being significantly affected by changes in the relative humidity of the outside air. In order to suppress oxygen permeability as much as possible, it is effective to increase the thickness of the intermediate layer. Also, as another layer constituting the multilayer film,
It is also a preferred embodiment to provide at least one strength reinforcing layer selected from paper, a porous polyamide layer, a porous polyester layer, and a porous polypropylene layer. In this case, the oxygen gas permeability of the strength reinforcing layer is 10,000 cc / m ² · da.
Those having y · atm or more are preferable.

The thermoplastic resin constituting the outer layer and the inner layer includes, for example, an olefin resin. Specifically, low-density polyethylene (LDPE), high-density polyethylene (HDPE), VLDPE, ethylene / α-olefin copolymer using a single-site catalyst, syndiotactic polypropylene copolymer using a single-site catalyst, ethylene・ Propylene copolymer (EP
C), polypropylene (PP), polystyrene (P
S), ethylene-vinyl acetate copolymer (EVA), poly-4-methylpentene-1 (TPX), ionomer (IO), ethylene-acrylate-based copolymer, ethylene-methacrylate-based copolymer, and their acids Modified products (graft polymers) are exemplified. In use, generally, one or more resin compositions of these resins or a composition comprising these and a processing aid are used.

In the usage of the above-mentioned thermoplastic resin, the outer layer and the inner layer may be the same resin or may be different. When the outer layer and the inner layer are made of the same thermoplastic resin, examples thereof include LDPE, VLDPE, PP, EVA, EPC, an ethylene / α-olefin copolymer using a single-site catalyst, TPX, and PS. In this case, the thickness of the inner layer is usually 1/2 or less, preferably 1 / of the thickness of the outer layer.
It is as follows.

Further, a heat-sealing resin may be used for the inner layer. As a specific combination, for example, LDPE and EVA, PP and EVA, LLDPE
And VLDPE, IO and EVA, PP and LDPE, IO and LDPE, PP and TPX, PP and PS, PP and IO, H
DPE and EVA, IO and TPX, IO and PS, LDPE
And TPX, LDPE and PS, HDPE and TPX, HDP
E and PS, LLDPE and TPX, EVA and PS, EVA
And TPX, TPX and PS, LLDPE and PS, VLDP
E and EVA, VLDPE and TPX, VLDPE and PS, and the like.

Each of the outer layer and the inner layer may be a single layer or a plurality of layers. In any case, the thickness of the outer layer is such that the water vapor permeability (W ₀ ) is 50 g · m ⁻² · 24
hr ^-1 (40 ° C, 90% humidity) or less, preferably 45g ・ m ^-2
· 24 hr or ^-1 (same) may be as to become below, the thickness of the outer layer, it is desirable also functions as a reinforcing layer is 10μm or more in consideration. On the other hand, when the inner and outer layers are thicker, the permeability of carbon dioxide decreases, so the thickness of the outer layer is usually selected from the range of 10 to 60 μm, more preferably 10 to 50 μm, and the thickness of the inner layer is also preferably 5 to 50 μm. Preferably 10-50 μm
Is appropriately selected from the range. In particular, when the outer layer and the inner layer are made of the same thermoplastic resin, the thickness of the inner layer is preferably 1/2 or less, preferably 1 / or less of the thickness of the outer layer.

The bonding between the intermediate layer and the outer layer and the bonding between the intermediate layer and the inner layer may be direct bonding. In some cases, an adhesive resin layer may be interposed. As the adhesive resin, a thermoplastic resin containing a carboxyl group or a derivative thereof, for example, a polyolefin graft-modified with maleic acid, fumaric acid, or the like, and an adipic acid-based polyester having a urethane-bonded carboxyl group are used.

[0035]

EXAMPLES In the following examples, oxygen permeability and carbon dioxide gas permeability were measured as follows.

(1) Oxygen permeability: The oxygen permeability was measured using an oxygen permeability measuring device (OX-TRAN 2/20 manufactured by Modern Control) under the conditions of 23 ° C. and 80% humidity. In the table, the unit is not shown, but all are cm ³ · m ^-2 · 24 hours
^-1 · atm ^-1 .

(2) Carbon dioxide permeability: The carbon dioxide permeability is measured by a carbon dioxide permeability measuring device (PER manufactured by Modern Control).
MATRANC-IV) was used and measured at 23 ° C. and 80% humidity. Units are not shown in the table, but c
m ³ · m ^-2 · 24hr ^-1 · atm ^-1 .

(3) Water vapor permeability (hereinafter referred to as “WV
TR "): The water vapor permeability of the inner layer film and the outer layer film was measured using a water vapor permeability measuring device (" L80-4000 "manufactured by LYSSY) at 40 ° C and 90% humidity. . The unit is not shown in the table,
g · m ^-2 · 24hr ^-1 .

(4) Equilibrium Water Absorption: A laminated film to be measured is made into a bag with a seal width of 5 mm and inner dimensions of 150 mm × 100 mm in width, and 50 cc of distilled water is added to the inside to make the relative humidity 100%. Seal. The bags are at 23 ° C and the relative humidity is 20%, 31%, 50%, 65%, 75%, 82%, 90%, respectively.
%, 98%, and then left in a humidified box for 10 days. Drain the distilled water and wipe with a tissue paper so that no water droplets adhere to the bag surface. Measure the weight of the bag (A).
Then, the bag was dried at 105 ° C for 1 hour, and the weight (B) was measured. The weight change before and after drying {(A)-(B)} and the weight after drying were measured.
From (B), the equilibrium water absorption (a) of the laminated film at each relative humidity is calculated.

[0040]

[Equation 4] Equilibrium water absorption of laminated film (a) = {(A) − (B)} × 100 / (B) (Equation 1)

Separately, this laminated film is separated into an outer layer, an inner layer, and an intermediate layer, and the outer layer and the inner layer are cut into 300 mm × 300 mm and placed in a box conditioned at 20% and 90% RH.
After standing for a day, the weight was measured. Next, these films were dried at 105 ° C. for 1 hour and weighed. From the weight change before and after the drying, the equilibrium water absorption of the outer layer and the inner layer at 20% RH and 90% RH was determined according to the above equation (1). calculated, to the outer layer the equilibrium water absorption (b _20, b ₉₀₎ and the inner layer the equilibrium water absorption and (c _20, c _90). The values obtained by averaging the equilibrium water absorption of the outer layer and the inner layer at the two relative humidity values thus obtained are defined as the outer layer equilibrium water absorption (b) and the inner layer equilibrium water absorption (c).

Equilibrium water absorption of the intermediate layer at each relative humidity
(d) was calculated as follows.

(D) = (a) − ｛(b) + (c)｝

[0043]

Example 1 A saponified ethylene / vinyl acetate copolymer (hereinafter, referred to as "EVOH") pellets were obtained from a hopper of a twin-screw extruder using polyethylene glycol having an average molecular weight of 600 (liquid, manufactured by Sanyo Chemical Co., Ltd.). (Hereinafter, “polyethylene glycol” is abbreviated as “PEG”) was supplied from the middle of the extruder and melt-kneaded to obtain a composition to prepare pellets (A). EVOH has an ethylene content of 32 mol% and a saponification degree of
99% (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., Soarnol DC
3212) was used. In the composition, EVOH contained 92% by weight, P
EG was 8% by weight.

On the other hand, polyvinyl alcohol having a saponification degree of 80%
82% by weight (hereinafter referred to as "PVA") and 18% by weight of PEG were blended with a Henschel mixer while the temperature was raised from room temperature to 120 ° C, and then melt-molded with an extruder to prepare a pellet (B). For PVA, "PVA P405" manufactured by Kuraray Co., Ltd. and having an average degree of polymerization of 500 was used, and for PEG, the same as described above was used.

Next, the pellet (A) 60% by weight and the pellet
(B) The mixture was mixed to give 40% by weight, and
It was melt molded with a 40 mm extruder to obtain a film having a thickness of 40 μm. Various physical properties of the obtained film were evaluated, and the results are shown in Table 1 together with the main constitution.

[0046]

Example 2 PVA of pellet (B) in Example 1:
The procedure was performed in the same manner as in Example 1 except that the weight ratio of PEG was changed from 82:18 to 93: 7. The results are shown in Table 1 together with the main constitution.

[0047]

Example 3 EVO of pellet (A) in Example 1
The H: PEG weight ratio of 92: 8 was set to 95: 5, and the pellet (B) P
The procedure was performed in the same manner as in Example 1 except that the weight ratio of VA: PEG was changed to 82:18 to 87.5: 12.5. The results are shown in Table 1 together with the main constitution.

[0048]

Example 4 The composition of Example 3 was used as an intermediate layer, and a low-density polyethylene (“Sumikacene F200” manufactured by Sumitomo Chemical Co., Ltd.) was used.
)) As the outer layer, an ethylene-vinyl acetate copolymer resin (NUC8425, manufactured by Nippon Unicar Co., Ltd.) as the inner layer, and an acid graft modified polyolefin (Mitsui Petrochemical Co., Ltd.)
Admer SF740 ") as the adhesive layer, and the outer layer / adhesive layer /
Melt co-extrusion molding was performed using a circular die co-extrusion apparatus at a resin temperature of 200 ° C. in a configuration of intermediate layer / adhesive layer / inner layer.

After discharging from the die, a film was formed by a conventional direct inflation method, and the thickness configuration was composed of an outer layer / adhesive layer /
A laminated film having an intermediate layer / adhesive layer / inner layer = 38/2/4/2/20 μm was obtained. Some of the results are shown in Table 1 together with the main configuration, and Table 2 shows the humidity dependence.

[0050]

Example 5 EVO of pellet (A) in Example 1
The same procedure as in Example 1 was carried out except that the weight ratio of H: PEG was changed to 100: 0, and the weight ratio of PVA: PEG of the pellet (B) was changed to 93: 7. The results are shown in Table 1 together with the main constitution.

[0051]

Example 6 EVOH: PE of the pellet (A) of Example 1
The weight ratio 92: 8 of G is 95: 5, and PVA: P of the pellet (B) is
The EG weight ratio 82:18 was set to 60:10 (weight ratio), and the pellets
(A): The same procedure as in Example 1 was carried out except that the weight ratio of the pellet (B), 60:40, was changed to 75:25. Table 1 shows the results together with the main configuration.
Shown in

[0052]

[Embodiment 7] The pellet (A) in Embodiment 1 was replaced with EVO.
The H: PEG weight ratio of 92: 8 was set to 95: 5, and the pellet (B) P
The procedure was performed in the same manner as in Example 1 except that the weight ratio of VA: PEG was 82:18 to 87.5: 12.5 and the weight ratio of pellet (A): pellet (B) was 60:40 to 75:25. Table 1 shows the results together with the main configuration.
Shown in

[0053]

Example 8 The pellet (A) of Example 1 was replaced with EVOH: PE
The weight ratio 92: 8 of G is 95: 5, and PVA: P of the pellet (B) is
The EG weight ratio 82:18 is set to 80:10 (weight ratio), and the pellets
(A): The same procedure as in Example 1 was carried out except that the weight ratio of the pellet (B), 60:40, was changed to 75:25. Table 1 shows the results together with the main configuration.
Shown in

[0054]

Example 9 The pellet (A) of Example 1 was replaced with EVOH: PE.
The weight ratio 92: 8 of G is 95: 5, and PVA: P of the pellet (B) is
The EG weight ratio 82:18 is 90:10 (weight ratio), and the pellets
(A): The same procedure as in Example 1 was carried out except that the weight ratio of the pellet (B), 60:40, was changed to 75:25. Table 1 shows the results together with the main configuration.
Shown in

[0055]

Example 10 The same procedure as in Example 4 was carried out except that the composition of Example 7 was used as an intermediate layer and an ionomer ("Iotek 3110" manufactured by Exxon) was used as an outer layer. Some of the results are shown in Table 1 together with the main configuration, and Table 3 shows the humidity dependence.

[0056]

Example 11 EVO of pellet (A) in Example 1
The H: PEG weight ratio of 92: 8 was set to 95: 5, and the pellet (B) P
The procedure was performed in the same manner as in Example 1, except that the weight ratio of VA: PEG was 82:18 to 87.5: 12.5, and the weight ratio of pellet (A): pellet (B) was 60:40 to 80:20. The results are shown in Table 1 together with the main constitution.

[0057]

Example 12 EVO of pellet (A) in Example 1
The H: PEG weight ratio of 92: 8 was set to 98: 2, and the pellet (B) P
The procedure was performed in the same manner as in Example 1, except that the weight ratio of VA: PEG was 82:18 to 87.5: 12.5, and the weight ratio of pellet (A): pellet (B) was 60:40 to 80:20. The results are shown in Table 1 together with the main constitution.

[0058]

Example 13 EVO of pellet (A) in Example 1
The H: PEG weight ratio of 92: 8 was set to 100: 0, the pellet (B) PVA: PEG weight ratio of 82:18 was set to 87.5: 12.5, and the pellet (A): pellet (B) weight ratio of 60:40. Was carried out in the same manner as in Example 1 except that the ratio was changed to 80:20. The results are shown in Table 1 together with the main constitution.

[0059]

Example 14 EVO of pellet (A) in Example 1
The H: PEG weight ratio of 92: 8 was set to 95: 5, and the pellet (B) P
The procedure was performed in the same manner as in Example 1 except that the weight ratio of VA: PEG was 82:18 to 87.5: 12.5 and the weight ratio of pellet (A): pellet (B) was 60:10 to 90:10. The results are shown in Table 1 together with the main constitution.

[0060]

Example 15 The pellet (A) of Example 1 was replaced with EVOH: P
The EG weight ratio of 92: 8 was set to 100: 0, and the pellet (A): pellet
The procedure was performed in the same manner as in Example 1 except that the weight ratio (B) of 60:40 was changed to 97: 3. The results are shown in Table 1 together with the main constitution.

[0061]

Example 16 EVOH: P of the pellet (A) of Example 1
The EG weight ratio of 92: 8 is 98: 2, and the pellet (A): pellet
The procedure was performed in the same manner as in Example 1 except that the weight ratio (B) of 60:40 was changed to 100: 0. The results are shown in Table 1 together with the main constitution.

[0062]

Example 17 "Gohsenol KM-11" having an average degree of polymerization of 1100 instead of PVA of Example 11 (Nippon Synthetic Chemical Industry Co., Ltd.)
The same procedures as in Example 11 were carried out except for the use of the same. The results are shown in Table 1 together with the main constitution.

[0063]

Example 18 A saponified ethylene / vinyl acetate copolymer ("Soarnol D2908" manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) having an ethylene content of 29 mol% and a saponification degree of 99 mol% was used in place of the EVOH of Example 11. Others were the same as Example 11. The results are shown in Table 1 together with the main constitution.

[0064]

Example 19 In place of EVOH of Example 11, a saponified ethylene-vinyl acetate copolymer ("Soarnol D3808" manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) having an ethylene content of 38 mol% and a saponification degree of 99 mol% was used. Others were the same as Example 11. The results are shown in Table 1 together with the main constitution.

[0065]

Example 20 The same operation as in Example 19 was carried out except that an ethylene glycol monomer was used instead of PEG used in Example 19. The results are shown in Table 1 together with the main constitution.

[0066]

COMPARATIVE EXAMPLE 1 The same procedure as in Example 1 was carried out except that the film used in Example 1 was made of only EVOH. The results are shown in Table 1 together with the main constitution.

[0067]

Comparative Example 2 PVA: PEG of pellet (B) of Example 1
Weight ratio of 82:18 to 88:12, pellet (A): pellet
The procedure was performed in the same manner as in Example 1 except that the weight ratio (B) of 60:40 was changed to 0: 100. The results are shown in Table 1 together with the main constitution.

[0068]

Comparative Example 3 The pellet (A) in Example 1 was replaced with EVO
The weight ratio of H: PEG 92: 8 was set to 100: 0, the weight ratio of PVA: PEG of the pellet (B) 82:18 was set to 98: 2, and the pellet
(A): Performed in the same manner as in Example 1 except that the weight ratio of the pellet (B), 60:40, was changed to 97: 3. The results are shown in Table 1 together with the main constitution.

[0069]

Example 21 Saponified ethylene / vinyl acetate copolymer 1
00 parts by weight and 5 parts by weight of polyethylene glycol were melt-kneaded with a twin-screw extruder to obtain pellets. Examples of the saponified ethylene / vinyl acetate copolymer include “Soarnol D2908” (trade name, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) (ethylene content 29 mol%, degree of saponification 99.4 mol%, melting point 188 ° C., melt viscosity 1.0
× 10 ⁴ poise (210 ° C., shear rate of 10 ² sec ⁻¹ )), and polyethylene glycol having an average molecular weight of 600 manufactured by Sanyo Chemical Industries, Ltd. was used.

Next, the blend pellets were used as an intermediate layer, an ionomer was used as an outer layer, an ethylene / vinyl acetate copolymer (shown as EVA in the table) was used as an inner layer, a polyolefin grafted acid-modified product was used as an adhesive layer, and a resin temperature of 200. ° C
And melt co-extrusion with a circular die co-extrusion apparatus. As an ionomer, Exxon Corporation's product name "Iotech 3110" (40 ° C, 90% relative humidity, 20μ
The water vapor permeability at m ^{2 was} 28.4 g · m ⁻² · 24 hr ⁻¹ ). Also, as the ethylene-vinyl acetate copolymer,
Product name “NUC8425” (40 ° C,
Water vapor permeability at 20% relative humidity 90%, 72.4 gm
^-2 · 24hr ^-1 ) was used. As the polyolefin grafted acid modified product, "Admer SF740" (trade name, MI at 190 ° C: 5.6) manufactured by Mitsui Petrochemical Co., Ltd. was used.

After the obtained parison was rapidly cooled, it was placed in a hot water bath (94
° C) for 10 seconds, immediately inflation film formation at a vertical × horizontal magnification = 2.5 × 2.5 times, a five-layer stretched laminated film having the thickness configuration shown in Table 4, was formed, and various physical properties were evaluated. Table 4 shows the results.

[0072]

Comparative Example 4 As shown in Table 4, the same as Example 21 except that the ionomer of Example 21 was used as the resin constituting the inner layer, the ethylene / vinyl acetate copolymer was used as the resin constituting the outer layer, and the thickness of the outer layer was 15 μm. I went to. The results are as shown in Table 4.

[0073]

Example 22 Instead of the saponified ethylene / vinyl acetate copolymer of Example 21, the trade name "Soarnol DC3212" (manufactured by Nippon Synthetic Chemical Industry Co., Ltd. (ethylene content 32 mol%, saponification degree 99.4 mol%) , Melting point 183 ℃, melt viscosity,
The procedure was performed in the same manner as in Example 21 except that 1.0 × 10 ⁴ poise (210 ° C., shear rate of 10 ² sec ⁻¹ ) was used. The results are as shown in Table 5.

[0074]

Comparative Example 5 Example 22 was repeated except that the inner layer EVA of Example 22 was used as the resin constituting the outer layer, the thickness was set to 15 μm, and the ionomer of the resin constituting the outer layer of Example 22 was used as the resin constituting the inner layer.
The same was done. The results are as shown in Table 5.

[0075]

Example 23 The same operation as in Example 21 was carried out except that low-density polyethylene was used in place of the ionomer as the resin constituting the outer layer of Example 21, the thickness of the layer was 38 μm, and molding was performed without further stretching. Low-density polyethylene is available from Sumitomo Chemical Co., Ltd. under the trade name “Sumikasen F200” (4
Water vapor permeability at 0 ° C, relative humidity 90%, 20μm is 33.
Using ^{8g · m -2 · 24hr -1)} . The results are as shown in Table 6.

[0076]

Comparative Example 6 Example 23 was repeated except that the low-density polyethylene as the outer layer constituting resin of Example 23 was used as the inner layer forming resin, and the EVA as the inner layer forming resin of Example 23 was used as the outer layer forming resin.
The same was done. The results are as shown in Table 6.

[0077]

Example 24 The same procedure as in Example 23 was carried out, except that the composition of the intermediate layer was the same as that of Example 22. The results are as shown in Table 7 below.

[0078]

Comparative Example 7 Example 24 was repeated except that the low-density polyethylene as the outer layer constituting resin of Example 24 was used as the inner layer forming resin, and the EVA as the inner layer forming resin of Example 24 was used as the outer layer forming resin.
The same was done. The results are as shown in Table 7.

[0079]

Comparative Example 8 The intermediate layer and the inner layer were made of the same resin as in Example 21, except that the thickness of the inner layer was 30 μm, the resin of the outer layer was the same EVA as the inner layer, the thickness was 20 μm, and the molding conditions Was performed in the same manner as in Example 23 to obtain an unstretched laminated film. The results are as shown in Table 8.

[0080]

Comparative Example 9 The intermediate layer was made of the same constituent resin as in Example 21.
The resin constituting the inner layer and the outer layer was low-density polyethylene, and the resin constituting the adhesive layer was a modified polyolefin graft acid.
The low-density polyethylene is Sumikasen L708, a product name of Sumitomo Chemical Co., Ltd. (MI is 10, density is 0.918 g / cm ³ )
Was used. As the polyolefin grafted acid modified product, "ADMER SF750" manufactured by Mitsui Petrochemical Co., Ltd.
(MI was 4.7). The constituent resin of each layer is melt-kneaded by a separate extruder, and the resin temperature is adjusted by a T-die strong extruder.
Melt co-extrusion at 00 ° C, outer layer, adhesive layer, intermediate layer, adhesive layer,
The thickness of each inner layer is 20μm, 5μm, 19μm, 5μm
, 17 μm. The results are as shown in Table 8.

[0081]

The selectively permeable film of the present invention has a relatively small oxygen permeability and a large ratio of the carbon dioxide gas permeability to the oxygen permeability. Therefore, it is extremely useful to use it as a single layer or a laminate for packaging water-containing foods, particularly for packaging foods that emit carbon dioxide, for example, fermented foods such as cheese and kimchi.

[0082]

[Table 1]

[0083]

[Table 2]

[0084]

[Table 3]

[0085]

[Table 4]

[0086]

[Table 5]

[0087]

[Table 6]

[0088]

[Table 7]

[0089]

[Table 8]

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Tomonori Hosoda 18-13 Kamitamari, Tamari-mura, Niiji-gun, Ibaraki Pref.

Claims (10)

[Claims] 1. A saponified ethylene / vinyl acetate copolymer having an ethylene content of 20 to 50 mol% and a saponification degree of a vinyl acetate component of 96 mol% or more, 50 to 98 wt%, and a saponification degree of 60 to 95 mol. 0 to 45% by weight of polyvinyl alcohol and monomers of either alkylene glycol or hydroxy acid,
At least one selected from the group consisting of oligomers and polymers, and having an average molecular weight of 4,000 or less 0.1% by weight or more,
A permselective film of a composition having a usage amount equal to or lower than the saturation solubility with respect to the sum of the contents of the saponified ethylene / vinyl acetate copolymer and the polyvinyl alcohol. 2. The selectively permeable film according to claim 1, wherein at least one selected from the group consisting of monomers, oligomers and polymers of either alkylene glycol or hydroxy acid is polyethylene glycol. 3. A selectively permeable film comprising at least three layers of an outer layer, an intermediate layer and an inner layer, wherein the intermediate layer comprises the composition according to claim 1 or 2. 4. The water vapor transmission rate of the outer layer (40 ° C., 90% humidity) and the water vapor transmission rate (W ₁ ) of the inner layer (40 ° C., 90%)
% Humidity) is [1 number] equation W ₀ <permselective film of claim 3, wherein satisfying ^{50g · m -2 · 24hr -1 W} 0 ≦ W I 5. The selectively permeable film according to claim 3, wherein at least one layer selected from paper, a porous polyamide layer, a porous polyester layer, and a porous polypropylene layer is provided as the strength reinforcing layer. 6. The permselective film according to claim 1, which is used for packaging food containing water. 7. The permselective film according to claim 6, wherein the water-containing food is a carbon dioxide-generating food. 8. The selectively permeable film according to claim 6, wherein the water-containing food is a fruit and vegetable. 9. The selectively permeable film according to claim 7, wherein the carbon dioxide-generating food is a fermented food. 10. The permselective film according to claim 9, wherein the fermented food is a cheese product or a whip.