JP2000246843A - Multilayer film for packaging storage meat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve barrier properties, a mechanical strength, and storage meat charging efficiency by incorporating at least one layer of a resin composition containing a specific ethylene-vinyl alcohol copolymer, a polyamide resin and an ethylene-unsaturated carboxylic acid copolymer or its metal salt in a multilayer film for packaging storage meat. SOLUTION: The multilayer film for packaging storage meat comprises one resin composition layer containing 50 to 95 wt.% of an ethylene-vinyl alcohol copolymer containing 20 to 60 mol% of an ethylene content and a saponification degree of 85% or above of a vinylester component by using an alkali catalyst from the copolymer of the ethylene and the vinylester, 0.2 to 25 wt.% of polyamide resin such as a polycaproamide (nylon-6), a polyundecaneamide (nylon-11), polylauryl lactam (nylon-12) or the like, and 0.5 to 40 wt.% of an ethylene-unsaturated carboxylic acid copolymer or its metal salt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an ethylene-vinyl alcohol copolymer (A) and a polyamide resin which are excellent in barrier properties, mechanical strength, flexibility, stretchability, shrinkage, appearance and work efficiency of filling meat. (B) and a resin composition layer composed of an ethylene-unsaturated carboxylic acid copolymer or a metal salt thereof (C), or an ethylene-vinyl alcohol copolymer (A), a polyamide resin (B), an ethylene-unsaturated Carboxylic acid copolymer or its metal salt (C) and 11
The present invention relates to a multilayer film for meat and meat packaging containing at least one resin composition layer composed of a thermoplastic resin (D) other than the above resin having the following solubility parameter (calculated from the Fedors equation).

[0002]

2. Description of the Related Art Hydrophobic thermoplastic resins such as polyolefins and polystyrenes are used in containers such as films, bottles and cups in the field of food packaging because of their excellent melt moldability, secondary processing properties, mechanical properties and economy. In the non-food field, it is widely used for daily necessities, home electric parts, automobile parts and the like. In addition, multilayer structures of these resins and ethylene-vinyl alcohol copolymer (hereinafter abbreviated as EVOH) are widely used in the field of foods and the like that require a barrier property against oxygen, flavor and the like.

Attempts have been made to use EVOH-based films as a multilayer film for meat and meat packaging by taking advantage of the above-mentioned properties. However, EVOH-based films are less flexible than polyvinylidene chloride (hereinafter abbreviated as PVDC) -based films. In addition, EVOH-based films have the disadvantage that the drop strength at low temperatures, especially for preserving meat, is weak, and they are easily broken.

[0004] In addition, when meat with bone is packaged, particularly in the case of heat shrink wrapping, the piercing strength of the EVOH-based film is low, so that the tip of the bone may pierce the meat packaging film and cause breakage. Therefore, at present, packaging is performed after covering the bone portion with a cloth or the like, but this is not sufficient, and damage may occur during vacuum packaging or heat shrink packaging. Furthermore, EVOH-based films are generally hard, and there is still a problem that the filling efficiency of meat is lower than other films.

[0005] Further, when an EVOH-based film is used as a heat shrinkable meat packaging film, there is a drawback that a melt hole is easily generated in the heat shrinking step. In addition,
Melt hole referred to in the present invention, when packaging meat using a heat shrinkable meat packaging film, in the step of blowing hot air or hot water to thermally shrink the film,
A hole formed in the film because hot air or hot water is sprayed on the portion where the film and the meat surface do not adhere.

The heat-shrinkable meat and meat packaging film is usually stretched. However, since the EVOH-based film generally has poor stretchability, the heat-shrinkable meat and meat packaging film using the EVOH-based film is not stretched. Deterioration of gas barrier properties due to poor thickness distribution due to unevenness and shrinkage unevenness,
Furthermore, poor appearance is a problem.

To solve such a problem, it is conceivable to laminate the EVOH film with another thermoplastic resin, but this is not always sufficient.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a barrier, mechanical strength, flexibility, stretchability, shrinkage,
An object of the present invention is to obtain a multi-layer film for packaging meat, which is excellent in meat filling work efficiency and appearance.

[0009]

The object of the present invention is to provide an ethylene-vinyl alcohol copolymer (A) having an ethylene content of 20 to 60% by mole and a degree of saponification of a vinyl ester component of 85% or more by 50 to 95% by weight; Polyamide resin (B) 0.2
A resin composition layer consisting of 0.5 to 25% by weight and 0.5 to 40% by weight of an ethylene-unsaturated carboxylic acid copolymer or a metal salt thereof (C), or an ethylene content of 20 to 60% by mole, Ethylene-vinyl alcohol copolymer (A) having a degree of saponification of 85% or more (A) 50 to 85% by weight, polyamide resin (B) 0.2 to 25% by weight, ethylene-unsaturated carboxylic acid copolymer or a metal salt thereof (C)
A resin composition layer consisting of 0.5 to 40% by weight and 0.5 to 40% by weight of a thermoplastic resin (D) other than the above resin having a solubility parameter (calculated from the Fedors equation) of 11 or less, This is achieved by using a multi-layer film for animal meat packaging containing layers.

In the present invention, the thermoplastic resin (D) used has an elastic modulus at 20 ° C. of 500 kg.
/ Cm ² or less.

In the present invention, it is preferable to laminate a layer made of a polyamide resin on both sides of the resin composition layer without interposing an adhesive layer.

In the present invention, the content of alkali metal ions in the resin composition is preferably 1 to 35,000 ppm.

In the present invention, the ion content of at least one metal selected from zinc, magnesium and calcium in the resin composition is 400 to 50,000.
It is preferably ppm.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The ethylene-vinyl alcohol copolymer (A) (hereinafter referred to as EVOH) used in the present invention is obtained by saponifying a copolymer comprising ethylene and vinyl ester using an alkali catalyst or the like. Obtained. A typical example of the vinyl ester is vinyl acetate, but other fatty acid vinyl esters (such as vinyl propionate and vinyl pivalate) can also be used. EVOH can contain 0.0002 to 0.2 mol% of a vinylsilane compound as a copolymerization component.
Here, as the vinylsilane-based compound, for example, vinyltrimethoxysilane, vinyltriethoxysilane,
Vinyl tri (β-methoxy-ethoxy) silane and γ-methacryloxypropylmethoxysilane.
Among them, vinyltrimethoxysilane and vinyltriethoxysilane are preferably used. Further, other comonomer such as propylene, butylene, or unsaturated carboxylic acid such as (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate and the like, as long as the object of the present invention is not hindered. Acids or esters thereof and vinylpyrrolidone such as N-vinylpyrrolidone can also be copolymerized.

The ethylene content of EVOH (A) used in the present invention is 20 to 60 mol%, preferably 25 to 5 mol%.
It is 5 mol%, more preferably 25 to 50 mol%. If the ethylene content is less than 20 mol%, the gas barrier property under high humidity is reduced, and the melt moldability is also deteriorated. If it exceeds 60 mol%, sufficient gas barrier properties cannot be obtained.

The EVOH (A) used in the present invention
The degree of saponification of the vinyl ester component is 85% or more,
It is preferably at least 95%, more preferably at least 98%.
If the degree of saponification is less than 85%, not only does the gas barrier property at high humidity decrease, but also the thermal stability of EVOH deteriorates, and gels are likely to be generated in molded products.

The preferred melt flow rate (MFR) of the EVOH (A) used in the present invention (190 ° C., 2160
g load) is 0.1 to 50 g / 10 min. , Optimally 0.5 to 30 g / 10 min. It is. However, the melting point is 1
2160g if near 90 ° C or above 190 ° C
It is measured at a plurality of temperatures above the melting point under load, and the reciprocal of the absolute temperature is plotted on the abscissa and the logarithm of the MFR is plotted on the ordinate in a semilogarithmic graph. These EVOH
The resins can be used alone or in combination of two or more.

The polyamide resin (B) used in the present invention
Is a polymer having an amide bond, for example, polycaproamide (nylon-6), polyundecaneamide (nylon-11), polylauryl lactam (nylon-12), polyhexamethylene adipamide (nylon-
6,6), polyhexamethylene sebacamide (nylon-
6,12), caprolactam / lauryl lactam copolymer (nylon-6 / 12), caprolactam / aminoundecanoic acid polymer (nylon-6 / 1)
1), a caprolactam / ω-aminononanoic acid polymer (nylon-6, 9), a caprolactam / hexamethylenediammonium adipate copolymer (nylon-6 / 6,
6), caprolactam / hexamethylenediammonium adipate / hexamethylenediammonium sebacate copolymer (nylon-6 / 6,6 / 6,12), polymer of adipic acid and meta-xylylenediamine, or hexamethylenediamine And aromatic nylon which is a polymer of m, p-phthalic acid and the like. Each of these polyamide resins can be used alone,
Two or more kinds may be used as a mixture.

The melting point of the polyamide resin (B) is preferably 175 to 240 ° C., more preferably 178 to 240 ° C.
235 ° C, most preferably 180-230 ° C. When the melting point of the polyamide resin (B) exceeds 240 ° C., the stretchability and the shrinkage deteriorate. Further, since the EVOH and the polyamide resin react and gel during the melting process at a high temperature, the melting point of the polyamide resin (B) is preferably 240 ° C. or less from the viewpoint of suppressing the thermal deterioration of the blend composition.
It is more preferable that the temperature is 0 ° C. or lower.

The polyamide resin (B) used in the present invention
Suitable melt flow rate (MFR) (210 ° C., 2
(Under a load of 160 g) is 0.1 to 50 g / 10 min. , Optimally 0.5 to 30 g / 10 min. It is. However, those having a melting point of around 210 ° C. or exceeding 210 ° C.
Measured at a plurality of temperatures above the melting point under a load of 60 g, the reciprocal of the absolute temperature is plotted on the horizontal axis and the logarithm of MFR is plotted on the vertical axis in a semilogarithmic graph.

The ethylene-unsaturated carboxylic acid copolymer or its metal salt (C) used in the present invention refers to a polymer obtained by copolymerizing ethylene and an unsaturated carboxylic acid, or a carboxylic acid component thereof. It means a metal salt obtained by summing. Here, it is particularly preferable that ethylene and the unsaturated carboxylic acid are randomly copolymerized, and the effect of the present invention is significantly increased as compared with the case where a copolymer obtained by grafting the unsaturated carboxylic acid to polyethylene is used. Can be improved. The reason that the random copolymer or its metal salt is superior to the graft copolymer is that it is difficult to obtain a high acid content necessary for exhibiting compatibility with the graft copolymer. Further, in the case of a graft copolymer of an unsaturated carboxylic acid, for example, maleic anhydride, EV
It may not be preferable because a hydroxyl group in OH reacts with a carboxyl group in the graft copolymer or gel fisheye is generated. In particular, when melt molding is performed for a long time, the generation of gel fish eyes may increase.

The content of the unsaturated carboxylic acid is preferably 2 to 15 mol%, more preferably 3 to 12 mol%. As unsaturated carboxylic acids, for example, acrylic acid,
Examples thereof include methacrylic acid, ethacrylic acid, maleic acid, monomethyl maleate, monoethyl maleate, and maleic anhydride, and acrylic acid or methacrylic acid is particularly preferable. Other monomers that may be included in the copolymer include vinyl acetate, vinyl esters such as vinyl propionate, methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, and n-acrylate. -Butyl, 2-ethylhexyl acrylate, methyl methacrylate, isobutyl methacrylate, unsaturated maleic esters such as diethyl maleate, carbon monoxide and the like.

In the present invention, it is particularly preferable to use a random copolymer of ethylene and an unsaturated carboxylic acid as the ethylene-unsaturated carboxylic acid copolymer (C) as described above. Is more preferably used. It is considered that the reason why the ionomer is superior is that the ionomer has a higher polarity and therefore has higher compatibility with the polyamide resin (B).

Examples of the metal ion in the metal salt of the ethylene-unsaturated carboxylic acid copolymer include alkali metals such as lithium, sodium and potassium, alkaline earth metals such as magnesium and calcium, and transition metals such as zinc. Particularly, the case where zinc is used is preferable in view of compatibility with the polyamide resin. The degree of neutralization of the metal salt of the olefin-unsaturated carboxylic acid copolymer is preferably 100% or less, particularly preferably 90% or less, and more preferably 70% or less. The lower limit of the degree of neutralization is usually 5% or more, especially 1%.
0% or more, more preferably 30% or more.

The preferred melt flow rate (MFR) of the ethylene-unsaturated carboxylic acid copolymer or its metal salt (C) (at 190 ° C. under a load of 2160 g) used in the present invention is 0.05 to 50 g / 10. Min, more preferably 0.5 to 30 g / 10 min. These ethylene-unsaturated carboxylic acid copolymers or metal salts thereof can be used alone or in combination of two or more.

The thermoplastic resin (D) used in the present invention
Is a thermoplastic resin different from the components (A), (B) and (C), and it is important that the solubility parameter is 11 or less. When the solubility parameter of the thermoplastic resin (D) exceeds 11, the four components (A), (B), (C),
The compatibility between (D) is reduced, and the mechanical strength, flexibility, stretchability, shrinkage, appearance, filling efficiency of meat, etc. of the multilayer film for meat packaging are significantly reduced.

Examples of the thermoplastic resin (D) having a solubility parameter of 11 or less include polyolefin-based resins, styrene-based resins, and polyvinyl chloride-based resins. Among them, polyolefin-based resins are most preferable, and high-density or low-density polyethylene, polypropylene, homopolymers of α-olefins such as polybutene-1, ethylene,
Copolymers of α-olefins selected from propylene, butene-1, hexene-1 and the like are exemplified. Further, those obtained by copolymerizing the following components with an α-olefin: diolefin, vinyl compounds such as vinyl chloride and vinyl acetate, and unsaturated carboxylic esters such as acrylic acid esters and methacrylic acid esters are also included. Examples of the styrene resin include polystyrene, acrylonitrile-butadiene-styrene copolymer resin (ABS), acrylonitrile-styrene copolymer resin (AS), and a copolymer of a vinyl aromatic compound and a conjugated diene compound. These thermoplastic resins can be used alone or in combination of two or more.

In the present invention, the elastic modulus (ASTM) of the thermoplastic resin (D) used at 20 ° C.
D882) is preferably 500 kg / cm ² or less. More preferably, it is 400 kg / cm ² or less, and still more preferably, it is 300 kg / cm ² or less.

In the present invention, beef meat refers to raw meat in addition to raw meat.
Artefacts, such as ham, sausage, baked pork, etc.
Multilayer film for livestock meat packaging such as irregular shaped
Has high flexibility and high resistance to bending.
Is preferred. In addition, in a preferred embodiment of the present invention,
One example is a heat-shrinkable meat packaging multilayer film.
You. In such applications, the desired shrinkage is obtained
In general, the film is used after being stretched.
You. However, in a process with a stretching step,
Barrier property due to poor thickness distribution of thermoformed product
And furthermore, poor appearance is a problem. Therefore, good bending resistance
Stretching with smaller force to develop bendability and stretchability
Multilayer film for meat packaging with low possible Young's modulus is desired
I have. In response to such demands, thermoplastics for EVOH (A)
It is effective to mix the thermoplastic resin (D),
The elastic modulus of the fat (D) at 20 ° C. is 500 kg
/ Cm ²The following is particularly effective.

Examples of the thermoplastic resin (D) having an elastic modulus of 500 kg / cm ² or less include very low density polyethylene (VLDPE), ethylene-vinyl acetate copolymer (EVA), and ethylene-methyl methacrylate copolymer. (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-propylene copolymer (EP
R), styrene-based elastomers (SEBS resin and the like) and the like.

The thermoplastic resin (D) used in the present invention has a melt flow rate (MFR) (190 ° C., 2160 g).
Under load) is preferably 0.05 to 100 g / 10 minutes,
More preferably, it is 0.05 to 50 g / 10 minutes, and most preferably 0.5 to 30 g / 10 minutes. However, the melting point is 190 ° C
Those near or exceeding 190 ° C were measured at a plurality of temperatures above the melting point under a load of 2160 g, and the reciprocal of the absolute temperature was plotted on the abscissa and the logarithm of MFR was plotted on the ordinate in a semilogarithmic graph, and extrapolated to 190 ° C. Expressed by value. Each of these thermoplastic resins (D) can be used alone,
Mixtures of more than one species can be used.

The object of the present invention is to provide an ethylene content of 20 to 6
0 mol%, an ethylene-vinyl alcohol copolymer (A) having a saponification degree of 85% or more (A) 50 to 95% by weight, a polyamide resin (B) 0.2 to 25% by weight, and an ethylene-unsaturated carboxylic acid copolymer or The metal salt (C) 0.5-40
Meat meat which is achieved by using a multilayer film for meat packing containing at least one resin composition layer consisting of wt% and has excellent barrier properties, mechanical strength, flexibility, stretchability, shrinkage, appearance and meat filling work efficiency. A multilayer film for packaging can be obtained. Above all, since the multilayer film for meat and meat packaging employing such a configuration has high transparency, the effect of improving the appearance is extremely large.

The content of EVOH (A) in the resin composition is 50 to 95% by weight, preferably 55 to 90% by weight, more preferably 60 to 85% by weight. If the content of EVOH (A) in the resin composition is less than 50% by weight, the gas barrier properties inherent in EVOH are insufficient, and
When the content of VOH (A) exceeds 95% by weight, the effects of improving the mechanical strength, flexibility and stretchability of the multilayer film for livestock meat are insufficient.

The polyamide resin (B) in the resin composition
Is 0.2 to 25% by weight, preferably 0.5 to 1% by weight.
It is 5% by weight, more preferably 1 to 10% by weight. The weight ratio of the polyamide resin (B) in the resin composition is 25% by weight.
When the ratio exceeds the above, the ratio of the polyamide resin (B) to the EVOH (A) increases, so that a gel is easily generated by the reaction between the two, and the effect of improving stretchability and shrinkage becomes insufficient. When the weight ratio of the polyamide resin (B) in the resin composition is less than 0.2% by weight, EVO
The compatibility between H (A) and the ethylene-unsaturated carboxylic acid copolymer or its metal salt (C) decreases, and the effect of improving the mechanical strength, flexibility, and appearance of the multilayer film for livestock meat is insufficient. Become.

The content of the ethylene-unsaturated carboxylic acid copolymer or its metal salt (C) in the resin composition is from 0.5 to
It is 40% by weight, preferably 1 to 35% by weight, more preferably 2 to 20% by weight. If the content of the ethylene-unsaturated carboxylic acid copolymer or its metal salt (C) in the resin composition is less than 0.5% by weight, the effect of improving the mechanical strength and flexibility of the multilayer film for livestock meat packaging is reduced. If the content becomes insufficient and the content of the ethylene-unsaturated carboxylic acid copolymer or its metal salt (C) exceeds 40% by weight, the gas barrier properties of the multilayer film for meat and meat packaging will be insufficient.

The object of the present invention is to provide an ethylene content of 2
0 to 60 mol%, ethylene-vinyl alcohol copolymer having a saponification degree of 85% or more (A) 50 to 95% by weight, polyamide resin (B) 0.2 to 25% by weight, ethylene-unsaturated carboxylic acid copolymer Combined or its metal salt (C) 0.5-4
0% by weight and a solubility parameter of less than 11 (Fed
(calculated from the ors formula) can be achieved by using a multi-layer film for livestock meat containing at least one resin composition layer composed of 0.5 to 45% by weight of a thermoplastic resin (D) other than the resin having the above-mentioned resin. . When the thermoplastic resin (D) is added to the resin composition, the transparency is slightly reduced, so that the effect of improving the appearance is slightly reduced.
The appearance of the obtained multi-layer film for livestock meat packaging can sufficiently be put to practical use, and by containing the thermoplastic resin (D), the effect of improving the mechanical strength, flexibility and stretchability in the present invention can be further improved. Can be improved.

The content of the thermoplastic resin (D) in the resin composition is 0.5 to 45% by weight, preferably 5 to 40% by weight, more preferably 10 to 30% by weight. When the content of the thermoplastic resin (D) in the resin composition is less than 0.5% by weight, the effect of improving the mechanical strength, flexibility and stretchability of the multilayer film for livestock meat is insufficient. When the content of the resin (D) is more than 45% by weight, the gas barrier property of the multilayer film for livestock meat is insufficient.

The method for adding the alkali metal ion contained in the resin composition used in the present invention is not particularly limited, but lithium chloride, potassium chloride, potassium acetate, sodium chloride and the like are previously added to EVOH.
And a method of dry blending with another resin and then melting. Among them, it is preferable to use sodium acetate by-produced in the saponification step at the time of EVOH production in terms of productivity and cost.

The preferred content of the alkali metal ion contained in the resin composition used in the present invention is from 1 to 35,00
0 ppm, more preferably 2 to 20,000 p
pm, most preferably 3 to 10,000 ppm.
By adding the alkali metal ion, the stretchability and shrinkage of the meat packaging film of the present invention are further improved, but the alkali metal ion content in the resin composition is 35,
If it exceeds 000 ppm, the coloring becomes easy and the appearance is adversely affected.

On the other hand, at least one selected from zinc, magnesium and calcium contained in the resin composition
The species metal ion content is 400-50,000p
pm, preferably from 450 to 30,000 pp
m, more preferably from 500 to 10,000 ppm, most preferably from 1,000 to 7,000 ppm. Selected from zinc, magnesium, calcium,
By containing at least one metal ion,
The effect of improving the mechanical strength, flexibility and appearance of the meat packaging film of the present invention is further improved. However, when the content of the ion of at least one metal selected from zinc, magnesium and calcium exceeds 50,000 ppm, the mechanical strength deteriorates and the stretchability also deteriorates. As a method for adding at least one metal ion selected from zinc, magnesium, and calcium, the composition may contain calcium acetate, calcium stearate, calcium chloride, magnesium acetate, magnesium stearate, magnesium chloride, zinc acetate, stearate. Zinc acid, a method of directly adding a metal salt such as zinc chloride, but zinc, magnesium, ethylene-unsaturated carboxylic acid copolymer,
A calcium metal salt may be prepared in advance and used as a component of the composition.

Each of the resin compositions can be easily obtained by melt-kneading the components with a usual melt-kneading apparatus. The method of blending is not particularly limited, but EVOH (A), polyamide resin (B), ethylene-unsaturated carboxylic acid copolymer or its metal salt (C), if necessary, thermoplastic resin A method in which (D) is simultaneously pelletized and dried with a single-screw or twin-screw extruder or the like, or first, a polyamide resin (B) and an ethylene-unsaturated carboxylic acid copolymer or its metal salt (C) are melt-mixed. -After cooling-pelletizing,
A method of dry blending the EVOH (A) with the thermoplastic resin (D) if necessary, and pelletizing and drying with a single screw or twin screw extruder, etc.

In particular, as shown in Examples described later, first, the polyamide resin (B) and the olefin-unsaturated carboxylic acid copolymer (C) are melt-mixed,
After granulation and drying, a method is preferable in which EVOH (A) is used alone, or EVOH and a thermoplastic resin (D) are dry-blended, granulated by a single screw or twin screw extruder, and dried. The reason for this is that when components are simultaneously melt-kneaded, components having good compatibility (for example, EV
Since the mixing of the OH (A) and the polyamide resin (B)) may proceed preferentially, it may be difficult to stably control the morphology of the resin composition composed of three or four components. However, polyamide resin (B)
And a olefin-unsaturated carboxylic acid copolymer (C) are prepared in advance so that the morphologically stable three-component or four-component compound is obtained without being greatly affected by the conditions at the time of melt mixing. A resin composition can be obtained. In particular, this effect is remarkable in a resin composition composed of four components in which the thermoplastic resin (D) is blended,
It is possible to obtain a stable compatibilizing effect between the EVOH (A) and the thermoplastic resin (D).

In the melt compounding operation, there is a possibility that the blend becomes non-uniform, and gels and lumps are generated and mixed. Therefore, an extruder having a high degree of kneading is used for the blend pelletizing. It is desirable to seal the hopper port with nitrogen gas and extrude at a low temperature.

From the viewpoint of preventing thermal degradation of EVOH due to reaction between EVOH (A) and polyamide resin (B),
The resin composition used in the present invention preferably contains at least one of a metal salt of a higher aliphatic carboxylic acid and a hydrotalcite compound.

Here, as the hydrotalcite compound, in particular, M _x Al _y (OH) _{2x + 3 y-2z} (A) _z ·
A hydrotalcite compound which is a double salt represented by aH ₂ O (M is Mg, Ca or Zn, A is CO ₃ or HPO ₄ , x, y, z, and a is a positive number) can be mentioned. In particular, the following are exemplified as particularly preferable ones.

[0046] _{Mg 6 Al 2 (OH) 16} CO 3 · 4H 2 O Mg 8 Al 2 (OH) 20 CO 3 · 5H 2 O Mg 5 Al 2 (OH) 14 CO 3 · 4H 2 O Mg 10 Al 2 ( _{OH) 22 (CO 3) 2} · 4H 2 O Mg 6 Al 2 (OH) 16 HPO 4 · 4H 2 O Ca 6 Al 2 (OH) 16 CO 3 · 4H 2 O Zn 6 Al 6 (OH) 16 CO 3 .4H ₂ O Mg _4.5 Al ₂ (OH) ₁₃ CO ₃ .3.5H ₂ O

Further, as the hydrotalcite compound,
JP-A-1-308439 (US Pat. No. 4,954,557)
The hydrotalcite-based solid solution described,
[Mg _0.75Zn_0.25]_0.67Al
_0.33(OH)₂(CO₃)_0.167・ 0.45H
₂Something like O can also be used.

The metal salt of a higher aliphatic carboxylic acid is a metal salt of a higher fatty acid having 8 to 22 carbon atoms.
Examples of higher fatty acids include lauric acid, stearic acid, and myristic acid, and examples of metals include sodium, potassium, magnesium, calcium, zinc, barium, and aluminum. Of these, alkaline earth metals such as magnesium, calcium and barium are preferred.

The content of the metal salt of these higher aliphatic carboxylic acids and the hydrotalcite compound is preferably 0.01 to 3 parts by weight, more preferably 0.05 to 3 parts by weight, based on the total weight of the resin composition. 2.5 parts by weight.

The resin composition used in the present invention may contain, in addition to the above resin components, appropriate additives (for example, heat stabilizer, plasticizer, ultraviolet absorber, antioxidant, coloring agent, filler, It is free to use other resins and the like as long as the object of the present invention is not hindered.

The method for obtaining the multilayer film of the present invention is not particularly limited. Molding methods practiced in the field of general polyolefins, for example, T-die molding, inflation molding, dry laminate molding,
Methods such as extrusion coating and coextrusion molding can be employed. Among them, a method of co-extrusion molding in which each resin is melted by an extruder and discharged and cooled in multiple layers from a round die or a T-die is preferable from the viewpoint that the process can be simplified and the production cost can be suppressed. The molding temperature is often selected in the range of 170 to 270 ° C. Further, a method of obtaining a multilayer film by producing a film having a specific configuration by co-extrusion molding and then performing dry lamination molding by combining these molding methods can also be adopted.

The multi-layer film for livestock meat of the present invention is used as a film having a multi-layer structure composed of at least two kinds of other base materials and two or more types, but the thickness and structure are not particularly limited. As the thermoplastic resin layer adjacent to the resin composition layer of the present invention, high-density, medium-density, or low-density polyethylene, vinyl acetate, acrylate, or copolymerized with α-olefins such as butene and hexene. Polyethylene (linear low density polyethylene (LLDP)
E), including very low density polyethylene (VLDPE)),
Ionomer resins, polypropylene homopolymers, or ethylene, butene, polyolefins such as modified polypropylene blended with rubber-based polymers, such as polypropylene copolymerized with α-olefins such as hexene, or maleic anhydride added to these resins, Or grafted thermoplastic resin, polyamide resin,
Examples include polyester resins, polystyrene resins, polyvinyl chloride resins, acrylic resins, polyurethane resins, polycarbonate resins, polyvinyl acetate resins, and the like. Among them, it is particularly preferable to use a polyamide resin.

Specific examples of the constitution of the multilayer film for meat packaging of the present invention include EVOH (resin composition containing EVOH), P
When expressed as A (polyamide resin), AD (adhesive), TR (thermoplastic resin), TR / AD / EVOH / A
D / TR, TR / AD / EVOH / PA / AD / TR,
TR / AD / PA / EVOH / PA, TR / AD / P
A / EVOH / PA / AD / TR and the like are exemplified as suitable ones. However, the layer configuration of the multilayer film for thermoforming of the present invention is not limited to the above layer configuration examples.
When a thermoplastic resin layer is provided on both outer layers, different resins may be used, or the same resin may be used. Further, scrap generated when performing extrusion molding, blow molding, thermoforming, or the like may be blended with the thermoplastic resin layer or separately provided as a recovery layer. The adhesive resin is not particularly limited, but may be an unsaturated carboxylic acid or its anhydride (such as maleic anhydride), an olefin-based polymer or copolymer (such as LLDPE, VLDPE, etc.), ethylene-
Those grafted to a vinyl acetate copolymer or an ethylene- (meth) acrylate copolymer are typical examples.

The multilayer film for meat packaging of the present invention is constituted by directly laminating a polyamide resin on both sides of a resin composition layer without an adhesive layer (PA / EVOH / P).
A) is particularly preferred. By adopting such a configuration, a great improvement effect can be obtained in terms of mechanical strength represented by stretchability, shrinkage and pinhole resistance of the multilayer film for livestock meat packaging.

Further, a thermoplastic resin layer is provided on at least one side thereof via an adhesive layer (TR / AD / P).
A / EVOH / PA) is preferable, and a thermoplastic resin layer is provided on both sides via an adhesive layer (TR / AD / PA).
/ EVOH / PA / AD / TR) are more preferred.

The multi-layer film for meat packaging of the present invention can be used as a multi-layer film for meat packaging for vacuum packaging by making a bag without stretching. Further, the multilayer sheet containing the resin composition layer of the present invention can be stretched to improve the shrinkability, thereby obtaining a multilayer film for heat shrinkable meat packaging. Although there is no particular limitation on the method for stretching the multilayer sheet, the produced multilayer sheet is reheated in a temperature range equal to or lower than the melting point of EVOH, and is subjected to at least a longitudinal direction and a lateral direction by a pantograph-type biaxial stretching machine or the like. A method of stretching 2.0 times or more is preferable.

The vacuum packaging is a packaging type in which meat is filled in a meat packaging multi-layer film, the inside is evacuated, and the mouth is sealed. In such a packaging format, since the meat is indefinite, the multilayer film is required to have particularly good mechanical strength and flexibility. Further, in order to visually recognize the contents, the film preferably has high transparency and excellent appearance.

The heat shrink wrapping is a packaging method in which meat is filled in a multi-layer film for meat wrapping, the inside is evacuated, the mouth is sealed, and the film is thermally shrunk by blowing hot air or hot water on the film. It is. By using such a technique, it is possible to obtain a package in which the film adheres to the contents and has excellent appearance with less wrinkling of the film. Since the heat shrinkable meat packaging film is required to have particularly shrinkability in addition to the required performance required for the vacuum packaging meat packaging film, it is preferable to use a stretched film.

[0059]

EXAMPLES The present invention will be further described below with reference to examples, but the present invention is not limited to these examples.

The following examples are shown in Tables 1 to 4 below.
Was used as a raw material. Here, Table 1 shows EVO
H (A), Table 2 describes the polyamide resin (B), Table 3 describes the ethylene-unsaturated carboxylic acid copolymer or its metal salt (C), and Table 4 describes the thermoplastic resin (D).

[0061]

[Table 1]

[0062]

[Table 2]

[0063]

[Table 3]

[0064]

[Table 4]

Example 1 Using the resins shown in Tables 1 to 4,
85% by weight of EVOH (A-1), polyamide resin (B
-1) A resin composition for a meat packaging film comprising 5% by weight and 15% by weight of an ethylene-methacrylic acid copolymer zinc salt (C-2) was obtained by the following method. That is, after the polyamide resin (B-1) and the ethylene-methacrylic acid copolymer zinc salt (C-2) are dry-blended, the mixture is put into a twin-screw vent extruder, and extruded at 220 ° C. into pellets. , The resulting blended pellets,
EVOH (A-1) was blended again by the same method to obtain a target resin composition.

The alkali metal ion content and the zinc content of the obtained resin composition were measured by the following methods. 10 g of the dried resin composition as a sample was put into 50 ml of a 0.01 N hydrochloric acid aqueous solution, and stirred at 95 ° C. for 6 hours. The aqueous solution after the stirring was quantitatively analyzed using ion chromatography to obtain an alkali metal ion content and a zinc content. The column is CIS manufactured by Yokogawa Electric Corporation.
-C25 was used, and the eluent was a mixed solution of a 5.0 mM aqueous tartaric acid solution and a 1.0 mM 2,6-pyridinedicarboxylic acid aqueous solution. In the determination, a calibration curve prepared with aqueous solutions of various metal hydrochlorides (for example, NaCl) was used.

The obtained resin composition, linear low-density polyethylene (LLDPE) “Ultzex 2 manufactured by Mitsui Chemicals, Inc.
022L ", MFR = 2.1 g / 10 min (210 ° C., 2
160g load), adhesive resin (carboxylic acid-modified polypropylene), "Admer NF500" manufactured by Mitsui Chemicals, MF
R = 3.5 g / 10 min (210 ° C., 2160 g load)｝, polyamide resin {“Ube Nylon 1 manufactured by Ube Industries”
030B ") in separate extruders, and using four types and seven layers of coextrusion equipment, LLDPE / adhesive resin / polyamide resin / resin composition / polyamide resin / adhesive resin / LL
DPE (30/8/15/15/15/8/30 μm)
To obtain a non-stretched seven-layer film (total layer thickness: 121 μm). Extrusion molding is LLDP
E at 220 ° C. using a single screw (65 mmφ)
At 220 ° C. using a single screw (40 mmφ), the polyamide resin was mixed with a single screw (40 m).
(mφ) at 250 ° C., and the resin composition was extruded at a temperature of 220 ° C. using a single screw (40 mmφ).

The obtained film is cut along a plane perpendicular to the flow direction of the film and a direction perpendicular thereto, the EVOH (A) on the cut surface is stained with iodine, and the vicinity of the center is observed with an optical electron microscope. As a result, it was confirmed that, in the resin composition layer, EVOH was a continuous phase and other resins were a dispersed phase.

The film thus obtained was evaluated for low-temperature drop strength, piercing strength, meat filling efficiency, melt hole, appearance, and barrier properties by the following methods.

(1) Low-temperature drop strength The low-temperature drop strength was determined by using the obtained film.
After filling 5 kg of boneless meat in a bag of 0 cm × 50 cm and deaeration of the inside, the meat vacuum package obtained by sealing the mouth was sufficiently humidified at 5 ° C.-65% RH. Place the package from a height of 1m on a concrete floor in a room at 5 ° C.
The bag surface and the floor surface were dropped so as to be parallel to each other, the state of damage was visually observed, and evaluated according to the following criteria 1 to 5. 5: No damage and extremely high commercial value. 4: There is almost no damage and the commercial value is high. 3: There is commercial value, although there is very slight damage. 2: There is damage, and the commercial value is small. 1: Extremely large damage, no commercial value.

(2) Puncture Strength As a substitute for meat, a bundle of 10 round cedar rods having a diameter of 3 cm and a length of 35 cm was prepared using a film obtained in the same manner as in the evaluation of the low-temperature drop strength. After packing in a bag of 30 cm × 50 cm and degassing the inside, the mouth was sealed to obtain a vacuum package. After sufficiently adjusting the humidity to 5 ° C.-65% RH, 10 packages are dropped on a concrete floor from a height of 1 m in a room at 5 ° C. so that the bag surface and the floor surface are parallel to each other. And evaluated according to the following criteria 1 to 5. 5: No damage and extremely high commercial value. 4: There is almost no damage and the commercial value is high. 3: There is commercial value, although there is very slight damage. 2: There is damage, and the commercial value is small. 1: Extremely large damage, no commercial value.

(3) Efficiency of Filling Livestock Meat 30 cm × 50 cm prepared using the obtained film
The evaluation was made by paying attention to the ease of filling 5 kg of meat with bone into the bag. If the bag is too hard, it tends to catch or break during filling, and if it is too soft, it sticks to the meat with bone and the filling efficiency decreases. Good 5>4>3>2> 1 bad

(4) External Appearance The external appearance was evaluated by visual observation of a meat meat vacuum package in which about 5 kg of meat with bone was vacuum-packaged, focusing on streaks, unevenness, wrinkles, and the like. Good 5>4>3>2> 1 bad

(5) Barrier Property The oxygen permeability was measured using the obtained film.
After filling 5 kg of boneless beef in a bag of 5 cm × 50 cm, degassing the inside, and sealing the mouth, 10 pieces of the meat meat vacuum package were obtained and kept at a constant temperature and high humidity of 5 ° C. to 65% RH. And 14 days later, the state of discoloration of the meat was noted, and visually judged. Good 5>4>3>2> 1 bad

(Example 2) Using the resin composition prepared in Example 1 and the resin used in Example 1, LLDPE
/ Adhesive resin / polyamide resin / resin composition / polyamide resin / adhesive resin / multilayer sheet having a structure of LLDPE (270/70/140/140/140/70 /
270 μm), and stretched 3.0 times in both the horizontal and vertical directions at 60 ° C. using a pantograph-type biaxial stretching machine.
LLDPE / adhesive resin / polyamide resin / resin composition / polyamide resin / adhesive resin / LLDPE (30/8
/ 15/15/15/8/30 μm).

The same evaluation as in Example 1 was performed using the obtained film. Table 5 shows the results. However, in Example 2, low-temperature drop strength, drop piercing strength, appearance, and oxygen permeability were evaluated using heat-shrink wrapped meat meat that was heat-shrink-packed by the following method. The meat shrink wrap was obtained by the following method. That is, using the obtained film, the meat is filled in a bag made to a size that does not hinder the filling of the meat, the inside is evacuated, and the mouth is sealed. Then, the package was sprayed with hot water of 90 ° C. for 5 seconds to thermally shrink the packaging film, and then immediately cooled by spraying with cold water to obtain a meat shrink package.

The stretchability of the film is determined by the following method.
And the state of melt hole generation was evaluated. The results are shown in Table 5.

(6) Stretchability The stretchability of the film was evaluated by visual observation, focusing on streaks, unevenness and wrinkles of the stretched film. Good 5>4>3>2> 1 bad

(7) Melt hole generation state A 90 ° C.
Hot air at a wind speed of 20 m / min. Then, the state of melt hole generation was visually evaluated, focusing on the time until melt hole generation and the speed of melt hole expansion. Good 5>4>3>2> 1 bad

(Examples 3 to 22, Comparative Examples 1 to 10) Instead of the resin compositions used in Examples 1 and 2, pellets having the resin compositions shown in Tables 5 to 7 were obtained. A non-stretched film and a stretched film were prepared and evaluated in the same manner as in Examples 1 and 2, except that the resin type and the mixing ratio were changed. The results are shown in Tables 5 to 7. In addition, as for the resin composition having an alkali metal concentration of less than 150 ppm, EVOH (A-1) is used as an EVOH in which the number of washings is increased during production and metal salts such as sodium acetate by-produced in the saponification step are removed. Was blended. For the resin composition having an alkali metal content of more than 150 ppm, sodium acetate was previously dry-blended with EVOH (A-1) so that the alkali metal content shown in Table 5 or Table 6 was obtained, and then pelletized. did. On the other hand, with respect to the resin composition having a zinc content of more than 4,600 ppm, zinc stearate was previously added to the zinc salt of the ethylene-unsaturated carboxylic acid copolymer so that the zinc content shown in Table 5 or Table 6 was obtained. (C-
Pelletized after dry blending in 1).

[0081]

[Table 5]

[0082]

[Table 6]

[0083]

[Table 7]

The three-component system of Examples 1 to 10 and Example 1
The four-component multilayer films of Nos. 1 to 22 exhibit excellent effects in both non-stretching and stretching. The three-component multilayer film is slightly superior in appearance and barrier properties to the four-component multilayer film, and the four-component multilayer film is slightly superior in strength to the three-component multilayer film. On the other hand, the multilayer films of Comparative Examples lacking the polyamide resin (B) or the ethylene-unsaturated carboxylic acid copolymer or its metal salt (C) were all weak in strength and not very good in appearance.

(Example 23) The resin composition prepared in Example 1, the LLDPE used in Example 1, and the adhesive resin were put into separate extruders, and three types and five layers of coextrusion equipment were used. Regarding a non-stretched five-layer film (total layer thickness 121 μm) obtained by co-extrusion to have a structure of LLDPE / adhesive resin / resin composition / adhesive resin / LLDPE (45/8/15/8/45 μm) The same evaluation as in Example 1 was performed. Table 8 shows the results.

Example 24 Using the resin composition prepared in Example 1 and the LLDPE and adhesive resin used in Example 1, LLDPE / adhesive resin / resin composition / adhesive resin / LLDPE (405/70/135/7
0/405 μm), and stretched 3.0 times in both the horizontal and vertical directions at 60 ° C. using a pantograph-type biaxial stretching machine. LLDPE / adhesive resin /
Resin composition / adhesive resin / LLDPE (45/8/15
/ 8/45 μm) was evaluated in the same manner as in Example 2. Table 8 shows the results.

(Example 25) An unstretched five-layer film was obtained in the same manner as in Example 23 except that the resin composition prepared in Example 11 was used, and the same evaluation as in Example 1 was performed. went. Table 8 shows the results.

Example 26 A stretched five-layer film was obtained in the same manner as in Example 24 except that the resin composition prepared in Example 11 was used, and the same evaluation as in Example 1 was performed. Was. Table 8 shows the results.

[0089]

[Table 8]

The multilayer film having the resin composition used in the present invention had excellent appearance and barrier properties even when the layer structure was changed, and also had excellent drop strength and piercing strength.

[0091]

According to the present invention, an ethylene-vinyl alcohol copolymer (A) having an ethylene content of 20 to 60 mol% and a saponification degree of a vinyl ester component of 85% or more is 50 to 95% by weight, and a polyamide resin (B) 0.2. ~ 25% by weight and ethylene-
Unsaturated carboxylic acid copolymer or its metal salt (C)
5 to 40% by weight of a resin composition layer, or 50 to 85% by weight of an ethylene-vinyl alcohol copolymer (A) having an ethylene content of 20 to 60% by mole and a vinyl ester component having a saponification degree of 85% or more. , Polyamide resin (B)
2 to 25% by weight, 0.5 to 40% by weight of the ethylene-unsaturated carboxylic acid copolymer or its metal salt (C) and 11
Thermoplastic resin (D) 0.5 other than the above resin having the following solubility parameter (calculated from Fedors equation):
The multilayer film containing at least one resin composition layer consisting of up to 40% by weight has excellent barrier properties, mechanical strength, flexibility, stretchability, shrinkage, meat filling work efficiency, and appearance, and is a multilayer for meat packaging. Useful as a film.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 77:00 23:08 101: 12) F-term (Reference) 3E086 AD01 AD16 AD19 BA04 BA15 BB01 BB66 BB67 BB85 BB90 CA04 CA22 4F100 AK01A AK01K AK07 AK46 AK46A AK46B AK46C AK63 AK69A AK69K AK70A AL05A AL05K AL07 AT00B AT00C BA03 BA06 BA44 CB03 EH20 GB23 JB16A JB16K JD01 JK07A JK08 JL01 YY00A 4J002 BB004 BB034 BB054 BB064 BB074 BB082 BB092 BB104 BB124 BB144 BB154 BB164 BB174 BB184 BB221 BB232 BC024 BC034 BC054 BC064 BD034 BE031 BH022 BN154 CL003 CL013 CL033 CL053 DD066 DD076 EG036 EG046 FD070 GF00 GG02

Claims (7)

[Claims] 1. An ethylene-vinyl alcohol copolymer (A) having an ethylene content of 20 to 60 mol% and a degree of saponification of a vinyl ester component of 85% or more, 50 to 95% by weight, and a polyamide resin (B) 0.2. ~ 25% by weight and ethylene-
Unsaturated carboxylic acid copolymer or its metal salt (C)
5 to 40% by weight of a resin composition layer,
Multilayer film for meat packaging including layers. 2. An ethylene-vinyl alcohol copolymer (A) having an ethylene content of 20 to 60 mol% and a saponification degree of a vinyl ester component of 85% or more, 50 to 85% by weight, and a polyamide resin (B) 0.2. -25% by weight, ethylene-unsaturated carboxylic acid copolymer or its metal salt (C) 0.5-
40% by weight and a solubility parameter of less than 11 (Fe
A multi-layer film for livestock meat packaging, comprising at least one resin composition layer composed of 0.5 to 45% by weight of a thermoplastic resin (D) other than the resin having the following formula (calculated from dors formula). 3. The multilayer film for meat packaging according to claim ^{2, wherein the} elastic modulus of the thermoplastic resin (D) at 20 ° C. is 500 kg / cm ² or less. 4. The multi-layered meat packaging according to claim 1, wherein a layer made of a polyamide resin is directly laminated on both sides of the resin composition layer without interposing an adhesive layer. the film. 5. The multilayer film for meat and meat packaging according to claim 1, wherein the content of alkali metal ions in the resin composition is 1 to 35,000 ppm. 6. The animal meat according to claim 1, wherein the ion content of at least one metal selected from zinc, magnesium, and calcium in the resin composition is 400 to 50,000 ppm. Multilayer film for packaging. 7. The multi-layer film for livestock meat packaging according to claim 1, wherein said resin composition contains an ethylene-vinyl alcohol copolymer (A) as a continuous phase component.