JPS58102762A - Low-temperature heat-shrinkable multilayer barrier film and its manufacture - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a low-temperature heat-shrinkable multilayer barrier film having four or more layers comprising a polyvinylidene condensate coelectric material as a core layer. For more details, see low-temperature heat shrinkability ↑lE (wrapping rate, shrinkage force),
Low-temperature toughness, high seal strength (oil resistance of the seal part, heat resistance, equilibrium impact resistance at low temperatures), gas barrier properties, optical/P'r properties such as transparency after heat shrinkage, and delamination resistance. This invention relates to a new heat-shrinkable film that has particularly excellent properties such as air-tightness when clipped, and is not limited to its uses. It can be used for deep drawing packaging and other purposes.

Hereinafter, a detailed explanation will be given using shrink wrapping as an example of its use.

Conventionally, the existence of heat-shrinkable films for tightly shrink-wrapping contents has been known for a long time.

Also, these films have a single ts that makes up the film.
+ When characteristics that cannot be achieved with IIN are required, there is a lot of research into combining differently pressed resins to create a laminated film that exhibits the characteristics of each resin in a composite form. .

However, while film patents to meet market demands are too wide-ranging and the required properties are being commercially available, the characteristics of each pine resin that can be exhibited in well-logging conditions There are limits, and there are various restrictions on the selection of the resin itself that can be laminated, and even if one property is improved, the other 10,000 properties may deteriorate, so a compromise must be made somewhere. As a result, the gap between market demands and existing film characteristics is only widening, and we are waiting for the emergence of a film that meets these demands.

For example, in the field of true shrink packaging, such as raw meat, processed meat, other fatty foods such as cheese, or products whose lifespan is extended by packaging with oxygen-blocking skewers, ryu-zai is especially used to improve the packaging finish of the product. Low-temperature shrinkability and gas repellency are required for packaging products that are sensitive to heat. These contents are generally uneven in shape and often have protrusions such as bones or packaging containers, so if you try to obtain a tight package that includes these items, In addition to the low-temperature shrinkability of the parts that are in contact with the material, it is also necessary to wrap the parts that are not in contact with the material at a sufficiently low temperature with minimal shrinkage, pressure, and stress. In the case of a film that has a shrinkage characteristic of 1/2 inch toward the high temperature side, and has a large temperature dependence of the retention rate, that is, it shrinks rapidly at a certain temperature, the contents may change color or change in quality. The phenomenon of uneven shrinkage caused by temperature differences occurs, which often leads to wrinkles, walnuts, etc., which make the surface of the package difficult to see, and which often result in defects such as tearing during transportation.

Therefore, shrinkable films are required to have dimensional stability at the film storage temperature, but during shrink packaging, the expression of shrinkage characteristics is closer to the lower temperature side and temperature dependence is small. On the other hand, the gas barrier property required of the film is a necessary property to enhance the long-term shelf life of the contents, and without this property, shrink packaging, especially for fatty foods, is unthinkable. However, even if the film satisfies the above two characteristics, it may be opaque, lack luster, become opaque (whitening) when heated, or the strength of the sealed portion may decrease.
Nothing will happen if the layers peel off. On the other hand, from the side of laminated film suppliers, it is technically difficult to design the quality of a film that has all of the above characteristics, so some of these characteristics are currently being sacrificed. On the other hand, films made of single vinylidene chloride copolymers (hereinafter referred to as PVD) have a good balance of properties such as shrinkability, gas barrier properties, oil resistance, and ligation properties, and have been widely used until now.

However, films made of ordinary PVD alone are still insufficient to provide sufficient shrinkage, and furthermore, they lack sufficient cold resistance, flexibility, heat sealability, etc. In order to provide stability and good stretchability, a particularly large amount of plasticizer or stabilizer must be added (Ha7)
Regardless, this amount is usually 6 to 10 wt%.

These materials may become undesirable, may deteriorate the properties of the film, may lack cold resistance, or may require an increase in the thickness of the barrier resin, as the barrier properties of the acid layer may deteriorate. There were problems such as:

In addition, in order to solve these problems even a little, it is
A 1-terene-monoacetate vinyl copolymer (hereinafter referred to as EV) with a high vinyl acetate content and excellent contact with the PVD copolymer resin is coated on both sides of the PVD copolymer coated with ~10 wt% of plasticizer.
A), for example, vinyl acetate content is 28, 18wt
There are methods to improve barrier properties by coextruding three layers of PVD copolymer into three layers and transferring a large amount of plasticizer from the PVD copolymer layer after stretching, but with these methods, the barrier properties do not change over time. Although it is stable, it also lacks heat and oil resistance. Also film.

There are problems such as stickiness and a tendency for the elastic modulus to be insufficient. In addition, in order to improve processing stability on one side of these EVA (the side that is sealed on the inside when used as a bag), films obtained by irradiating and crosslinking with electron beams (Japanese Patent Laid-Open No. 47-34F1
65 etc.). The manufacturing method for these products is iridescent and complicated, and crosslinking makes it difficult to seal the sealing part rather than improving oil resistance, resulting in poor high-temperature resistance and high-temperature oil resistance. There is.

Also, as a method that partially improves the above problems.

EVAJfi or low density polyethylene on one side of the PVD copolymer layer, and a 20-50μ ionomer resin alone on the other side via a thin layer of 0.2-3μ high VAC EVAJ- or ionomer resin EVA The mixed layer is placed directly on the vinylidene layer, and the PVD conjugate layer is kept in an amorphous state under narrow temperature conditions that are finely adjusted depending on the resin properties of each layer, for example, at a heating temperature of 84 to 93°C. The method of crystallization after stretching is disclosed in Japanese Patent Application Laid-Open No. Sho F12.
-47079, F+2-148577, 53-
No. 82888, No. 56-8994! 'i issue etc. are known. Although the above method is easier to manufacture than the above-mentioned methods, the stretching must be carried out under severe conditions, and the optical properties before and after use tend to be lower than the above-mentioned methods. Furthermore, there is a problem that the film layers may peel off due to oil infiltration from the cut surface of the film.

All of the above have their own characteristics and are excellent, but they are still lacking in low-temperature shrinkability and heat resistance, and when heated to a high degree of shrinkage, the film becomes opaque (
A phenomenon called whitening) can be seen. Furthermore, there is still a lack of toughness at low temperatures.

In order to overcome this phenomenon, the present inventors have finally completed the present invention as a result of long-term research into various resins, laminated structures, and stretching methods.

That is, the present invention consists of the following: At least one polymer selected from linear low-density polyurethane, tB, Zcarene-alpha olefin copolymer, density: 0.919/'' or less, soft IK, ilas) mer, tCI
(A), j-(B+
Adjacent to the specific PVD barrier 1-, at least one composite (ABC) layer consisting of C+ and C+, and on the surface layer (7 linear low-density polyethylene (LLDPE) selected from AI) Resin (S
) At least one cylinder with a total thickness of 2 to 25μ rAs L with a total ratio of 5 to 40%, 7. : 4
It is a film on mR. The manufacturing method is such that each layer is kept at a sufficiently low temperature, that is, below the crystalline melting point of the resin that is the main component and subcomponent of the above-mentioned mixed composition that becomes a living body, and more preferably below the Vicat softening point (hereinafter referred to as Vsp) of the mixed composition. This is a low-temperature stretching process.

Here, the composition in the mixed composition (ABC) layer (AJ is a relatively low crystalline Togane body that is intermediate between hard and soft,
Vinyl 1-stell monomer, aliphatic unsaturated monocarboxylic acid,
A monomer selected from the monocarboxylic acid/alkyl 1-stell derivatives is selected from the group of copolymers of L-terene, and these include preferably 1-terene monovinyl acetate copolymer (EVA).
), ethylene-acrylic acid ether copolymer (EEA),
Ethylene-, methacrylic acid methyl ester copolymer (
EMMA), ethylene-acrylic acid copolymer (F AA
), ethylene-methacrylic acid co-monomer (EMA) 5, or an electropolymer (Aimatsumer resin) in which at least a portion of a polymer having a carboxy group in which at least a portion of these is saponified is ionomerized. The amount of monomers other than ethylene in these copolymers is preferably 2 to 12 mol%, more preferably 3 to 10 mol%. When this amount is 2 mol % or more, sealability, flexibility, transparency, and various strength properties will be excellent. Also, 12 moles! If it is more than X, extrusion processability, miscibility with other components, etc. may be poor, and when processed into a film to form an outer layer, the surfaces may tend to block together, causing problems in handling. Furthermore, the Nord index of the resin when used as it is as a raw material is usually 0.2 to 1.0, preferably 0.3.
~5. If it is less than 0.2, there will be problems in the mixability and extrudability of the raw materials, and if it is more than that, the strength as a base material may be insufficient, and, for example, bubbles may easily burst during stretching, which is undesirable. Among the above, EVA is most preferable for use in the mixed composition layer, and its vinyl acetate group content is preferably 3 to 8 mol%, more preferably 3 to 7 mol%.
It is. Also, linear low density polyethylene (LLDPE)
) refers to linear low-density polyethylene obtained by medium, low-pressure, or even high-pressure processes, in particular those containing α-olefins such as propylene, phytene, pentene, hexene, heptene, octene, 4-methyl-1- 7 mol% or less, preferably 1 to 5 mol%, of at least one olefin selected from α-olefins having a carbon number of C3 to C12, such as pentene, and preferably has a melt index of 0.2. ~10゜Density 0.910~o
, 935y7ml. Also, DSO method (10℃/
Crystal melting temperature (m
p) refers to the temperature between 110°C and 125°C, and the density of low-density polyethylene branched by ordinary high-pressure method is 0.
915 to 0.927 f/7 cm", which is distinguished from those with a crystal melting temperature of 100 to 108°C.

Next, thermoplastic elastomer made of ethylene and α-olefin copolymer) is a soft copolymer of ethylene and one or more α-olefins selected from α-olefins having 3 to 12 carbon atoms. In some cases, a small amount of a hydrocarbon having a polyene structure, such as synclopentadiene, 1,4-hexadiene, ethylidene norbornene, etc., may be further monopolymerized.

α-olefins include propylene, butene-1, hexene-1, heptene-1ζ4'methyl-1-pentene, octene-1, etc., and propylene and butene-1 are preferred. The content of Etele/ in the copolymer is 20-9
5 moles, preferably in the range of 40 to 93 mole%, more preferably in the range of 65 to 90 mole%. More preferably 7
The content of the 5-9 layer is 1 mol %.

The properties of these copolymers include a density of 0.915115111 or less, preferably a ViCat softening point [: ASTMD/
1525 (value at load 1v4)] is 880°C or less, preferably 70°C or less, and the crystallinity (X-ray method) is 30X if it is generally a rubbery region and is substantially amorphous and can be stretched. It shall also include those with a low degree of partial crystallinity. Ethylene and α used in the present invention
-Olefin copolymers can also be qualitatively analyzed by infrared spectroscopy. Preferred is a copolymer of ethylene and propylene or butene-1, particularly preferably the former, or a copolymer containing a small amount of a compound having a diene structure, such as a vanadicum compound and an organic copolymer. Examples include thermoplastic elastomers that are random copolymers polymerized with an aluminum compound catalyst and have a melt index of 01 to 10, preferably 02 to 6.

These are supplied in the form of pellets, which are not block-shaped like general non-vulcanized rubber and do not cause cold flow, and have sufficient thermoplasticity to the extent that they can be extruded into films even when used alone. It is preferable to have one.

Next, the polymers are crystalline polypropylene and high molecular weight crystalline polybutene-1 (hereinafter abbreviated as IPP and PB-1, respectively), which are composed of components that are relatively hard and have a relatively high degree of crystallinity. vi Oa is preferably made of a relatively hard polymer having a softening point of 100° C. or higher. Polymer (
IPP, which is one of C), refers to crystalline polypropylene with high isotoughness, which is usually commercially available, and is a propylene homopolymer or a propylene and 7 mol%
Those containing the following copolymers with ethylene, butene-1, etc. or other α-olefins are preferred. Or they may be mixed arbitrarily.

The melt flow index is 0.1 to 30, preferably 0.5 to 20, more preferably 0.7 to 15. If the melt flow index is less than the above, there will be problems with mixing properties and optical properties during processing. It began to have
Use in large quantities above the above.

In this case, problems arise in extrusion stability and sealing stability.

In addition, -polybutene-1 is crystalline with a butene-1 content of 93 mol% or more and has a high molecular weight that also includes copolymers with other polybutenes, and is different from liquid and wax-like low molecular weight ones. , the melt index is 0. for the same reason as above.
2 to 10 are preferred.

Of the above, it is preferable to mainly use IPP. A mixture of IPP and PB-1 is also preferably used. In addition to the above, any hard polymers that have appropriate compatibility and dispersibility and meet the purpose of the present invention may also be used.

The layer consisting of the specific mixed composition (A B C) of the film of the present invention is the most important layer for exerting a strong cold stretching force, and is composed of the above-mentioned components, and the combination and mixing amount thereof are as follows: , preferably 0.90≧A/(A+B+c)≧
0.20.0.50≧B/(A10B10)≧0.05.
0.50≧c/(A+Et+c)≧005. More preferably 0.80≧A/(A+B〇)≧0.3
0.0.40≧B/(A+B10)≧0.10.0.4
5≧C (A+B+C)≧0.10.

If the amount of the soft component (B+) mixed is small, it becomes difficult for the mixture to exhibit a synergistic effect, and various physical properties deteriorate.For example, the strength of the film, optical properties, low temperature properties,
It has poor flexibility, sealability, stretchability, etc. Also, if there is too much, the film will become too soft and may cause locking.
0 components (tensile, impact strength, NFF (thermal,
Synergistically improves extrudability, modulus, heat seal range with other components, especially heat resistance, oil resistance, extrudability, modulus, heat seal range, adjacent PVD layer during use, especially at high shrinkage. It is highly effective in preventing the zigzag whitening phenomenon.

If the mixing amount is small, for example, the processability of the film and the unevenness of thickness due to the flow characteristics within the goo will deteriorate, and the heat sealing range and heat resistance will be insufficient, especially at high temperatures. The oil resistance between the parts is insufficient. On the other hand, if the amount is too large, low-temperature shrinkability, extrusion moldability, transparency, flexibility, impact strength, etc. will be deteriorated, so it is preferably within the above range. Here, the component IAJ preferably consists of a specific ethylene copolymer, and the aforementioned three components tA
In some cases, it is preferable for it to be the main component in a mixture of I, (BJ, and (C)).

Mixing only the same three components (AJ and component (C)) usually does not have very good miscibility or compatibility, and it is difficult to expect the synergistic effect mentioned above, but adding component (B) can overcome these drawbacks. 5. These reasons are due to the delicate interactions between the components (characteristics related to the structure of the copolymer with ethylene contained in AJ and other components, the crystal structure of the mixture, and This is thought to be due to complex synergistic effects such as the dispersion state of the mixture and the effects of processing.

Next, one of the greatest features of the present invention is that the (
It is important that the resin (S) selected from AJ is mainly composed of the aforementioned linear low density polyethylene (LLDPE). Its preferred range is melt index 0.2-10, density 0.910-o, 935y7ttt
? A more preferable range is melt index =
0.2-8, density: 0.910-0925 Gua cJ
It is. Even more preferably, the melt index is 0.
2 to 6. The lower limit of the melt index is because there is a limit to extrudability into a film, and the upper limit causes instability in the cold stretchability of the main layer (consisting of an ABC mixed composition) when used as a surface layer, and This is because, when made into a film, the sealing portion may have insufficient high-temperature oil resistance, insufficient film strength, etc. The lower limit of the density is determined by the resin manufacturing method, and the upper limit is determined by the instability of stretchability and the optical properties of the cold stretched film, especially after shrinkage, as in the case of the upper limit of the melt index mentioned above. There is a tendency for optical properties to deteriorate significantly (for example, Haze value, glossiness, etc.). Within the above range, there will be no deterioration of the processability and mechanical properties mentioned above, nor will it inhibit the mechanical properties of other layers, especially the ABC layer.On the contrary, due to the synergistic effect with other layers, these factors will be reversed. It became clear that there was a significant improvement. In particular, there are remarkable improvements in various strength properties, sealing properties, and bitemperature oil resistance properties. Also, DSC method (heating speed 10℃/
The peak value of the crystal melting temperature (mp) measured in minutes) is 11
Preferably, the temperature is 0 to 125°C.

Near-low-density polyethylene, which is the main component, may be mixed with other polymers to the extent that the above-mentioned properties are not significantly impaired, and the limit is 50% by weight of other polymers.
The extent is as follows.

Combining the above layer configurations synergistically improves the optical properties. For example, if the (ABC) layer alone lacks optical properties before and after shrinkage, this can be improved without impairing the overall properties. is one of its purposes. One of the other purposes is to improve the heat resistance and oil resistance (especially at high temperatures) of the film or the sealing part, and to improve the cold resistance, strength, and sealing properties (sealing range, sealing strength), etc. It is characterized by improved performance.

Next, the polyvinyl chloride/nylidene-based co-topolymer (P
VD ) is the peak value of the crystal melting temperature (abbreviated as mp) measured using a differential set calorimeter (DSC method), which is 14
It is important to use PVD in the range of 0 to 155° C., and the use of PVD in this range and the above-mentioned adjacent layers and surface layers will synergistically exhibit the various above-mentioned characteristics.

In general, PVD uses other copolymerizable monomers of 5 to 3 Fl wtX, such as vinyl chloride, acrylonitrile, acrylic acid alkyl esters, and other monomers, but are not limited to these and are within the above range. It's fine if it's in.

Furthermore, since these copolymers are easily thermally decomposed when used alone, a small amount of stabilizer or OJ plasticizer may be used according to a known method if necessary. In order to improve the stretchability or extrudability of PVD, a large amount of liquid plasticizer (e.g. 7-12vt
It is not recommended to use X). One reason is that
Normally, in the known method, stretching is possible without using a large amount of plasticizer, but in the method of the present invention, it is necessary to select specific compositions and combinations of layers other than the PVD layer. It doesn't have to be that way because it is.

If a large amount of the plasticizer is used illegally, the stretching may become unstable and punctures may occur easily.Other reasons (1)
One of the points is that when a polyelectronic plasticizer is used, the oxygen barrier performance of the film is greatly reduced and the film lacks the performance of a high barrier. To prevent this, an attempt has been made to improve the barrier properties as much as possible by introducing a layer that easily absorbs the plasticizer into the adjacent layer, such as an EVA layer with a high vinyl acetate group content of 28 wt% VAe, and absorbing it during long-term aging. etc. are publicly known. However, such a method has unstable quality and is different from that of the present invention.

Another problem is that if a large amount of plasticizer is used, the interlayers become extremely easy to peel off, and other properties such as heat resistance deteriorate.

In the present invention, for the above-mentioned reasons, additives commonly used in the art, such as epoxidized soybean oil as a stabilizer, acetate tributelanthrate and dioctyl adipate as plasticizers, are added in very small amounts of 3 wt% or less. It is preferable to use 2 wt% or less. If they are used in a small amount, there will be no problems as described above, and there will be virtually no change in barrier properties due to migration of a large amount of plasticizer, and it will be stable, especially <0 of the present invention. When a composition is used, such a phenomenon is even more difficult to see because of its oil resistance.

In addition, in the method of the present invention, each layer, especially the PVD layer, has a specific resin layer (AB) with a strong stretching force on both sides at a sufficiently low temperature.
Since the PVD layer (C layer) is sufficiently stretched, strong cold stretching is applied to the PVD layer, and it is thought that crystallization of PVD progresses and stabilizes during stretching along with the amount of the PVD layer. Surprisingly, even after 1 month, after the PVD crystallization of the layer has sufficiently progressed, stretching may be surprisingly successful, in which case even better results may be obtained. These are synergistic effects with other layers of the present invention, and give an impression of excellent performance in cold resistance, various strengths, low-temperature shrinkage characteristics, and optical properties before and after shrinkage.

Preferably, other non-migrating polymeric plasticizers include E.
Even when mixed with V8, oligomers, rubbery substances, etc.,
You may use a mixture of those that do not become cloudy and do not cause phase separation. In that case, the amount added is preferably 1 to 15%,
More preferably, it is 2 to 10% by weight.

Furthermore, the PVD used may be a paste with a relatively low degree of polymerization and good flow, in which case the phenomenon of carbonization due to decomposition is reduced and extrusion is possible.

The distance between the axes provides better processing stability during stretching. This type of PVD film, especially without stretching, is generally considered to be undesirable because it becomes brittle and tends to tear even after being rapidly cooled into a film after stabilization. If this temperature is higher than that of the present invention as in the conventional example disclosed in Japanese Patent Application Laid-Open No.
If it is stretched at a temperature of ~105°C, it will be inferior, and the result will be ÷i-, but in the case of the present invention, when it is sufficiently stretched in the cold to develop a synergistic effect with other specific layers. It is of a type suitable for In this way, it becomes possible to obtain an excellent film by processing without plasticizing, which is substantially free of low-molecular-weight migratory plasticizers.

The combination of each layer requires the above-mentioned ABC layer to be placed on both sides of the PVD layer adjacent to each other, and the number of layers is not particularly limited, but when represented on one side, it is at least one layer, if necessary, more.

Furthermore, in the present invention, eight layers are disposed on at least one outer surface layer to more synergistically compensate for the deficiencies in the above layers.

Further, other oil-resistant compositions may be used for other surface layers.

The above combinations can be expressed in abbreviations from the outside of the film to the inside as follows.

S/ABC'/PVD/ABC, ABC/PVD/AB
C/S, S/ABC'/PVD/'ABC/S.

S/ABC/ABC/PVD/ABC, S/ABC! /
AB(:!/PVD/ABC, S/ABC/ABC/P
VD/ABC! /'ABC/S,, EVA/ ABC/
PVD/ABC! /S, ionomer resin /ABC/P
VD/ABC/S etc.

The thickness composition ratio of each layer is preferably 35 to 5% of the total thickness, and the range is 4 to 35μ. The lower limit of the ratio and thickness is the level necessary to maintain excellent barrier properties and quality, and the oxygen barrier performance is 50 cc/m2day atm (23°C) or less,
Preferably 30 cc/m”reay atm (23°C
). However, this does not apply to applications that do not require much barrier property, or conversely, where it would be a problem to have so much barrier property.

The upper limit of the thickness composition ratio is the limit necessary to maintain low-temperature shrinkage properties or cold resistance, sealing properties, and other properties, especially low-temperature shrinkage properties, and if this is exceeded, the properties deteriorate.

Further, the upper limit of the thickness may be as long as the upper limit of the above-mentioned thickness composition ratio is maintained, but a layer that is too thick is not practically required.

The 8 layers forming the surface layer have a total thickness of 5 to 40,
The thickness range is preferably 2 to 25 microns. More preferably it is 3-20μ. The lower limit is the thickness necessary to serve as a surface layer, and the upper limit is because if it is too thick, the function of the ABC layer will deteriorate. Further, in the case of a resin having low stretchability under the conditions of the present invention for the surface layer, it is preferable that the ratio is low. The mixed resin layer, which is mainly composed of ABC, is generally 65-95% excluding the PVD layer.
The thickness ratio is 25 to 90% excluding the surface layer.

In addition, the overall thickness is usually 30 to 100 μm, preferably 3 μm for direct packaging of relatively large raw meat, processed meat, etc.
It is 5 to 80μ. However, when used as a particularly thin barrier packaging material, this is not the case;
It was found that it can be used satisfactorily as a μ film. This is due to the synergistic effect of the strength characteristics due to the characteristic layer structure, and the high strength and high barrier characteristics obtained by highly orienting nearly non-plastic PVD.

The reason for the thickness structure (mJ) and ratio (conversion) of each layer above is that the peak of mp of DSC' of the PVD layer is 140 to 15.
If the temperature is within the range of 5°C, it is necessary to arrange the above-mentioned ABC layer as the adjacent layer.
When VAc: 1'0.2 mol%, M process: 4) is used as an adhesive layer adjacent to both sides, and paying attention to the optical properties after shrinkage, there is no longer a whitening phenomenon at a shrinkage rate of 30% (vertical and horizontal average). occurs. When this film was sliced and a microscopic photograph of the cross section was observed, zigzag-like bending (hereinafter referred to as zigzag whitening) of the PVD layer was observed, and it was found that an abnormal phenomenon had clearly occurred. Such a film not only becomes white and blurred, making it difficult to see the contents, greatly reducing its commercial value, but also causing the gaps to peel off, reducing the strength of the sealed portion. When a specific ABC layer is constructed using a PVD layer within the above mp range, and all layers are stretched at a sufficiently low temperature under the conditions of the present invention, this phenomenon is hardly observed even when shrinking at 85°C. There wasn't. However, if PVD exceeding the upper limit of 155° C. is used, there is a tendency for zigzag whitening to occur even if an ABC layer is provided. Moreover, cold resistance also tended to deteriorate. Also, as mentioned above, PVD
This tendency was also observed when a large amount of plasticizer (6wtX or more) was used in the layer.

Furthermore, a PVD layer having an mp below the above-mentioned lower limit tends to have lower stretching stability, lower barrier properties, lower heat resistance, etc.

As described above, the film of the present invention can exhibit unprecedented excellent properties due to the synergistic effect of the specific layer of the specific PVD copolymer and the layers on both sides thereof.

The film of the present invention has a heat shrinkage rate of at least 15.25% at each temperature of 70°C and 80°C, preferably 2'0. 30X, more preferably 22.35X. This measurement method is based on the vertical position when immersed in specified warm water for 4 seconds
This is the average shrinkage rate in the horizontal direction.

The higher this value, the higher the low-temperature shrinkage performance, and
The smaller the difference between the two, the better the shrink wrapping with less temperature dependence during shrinkage. This value is in the practical range (,20
It is expressed as the value at which the difference in shrinkage rate is maximum at a temperature difference of 10°C in the range of 50X shrinkage), that is, the shrinkage gradient ( When expressed as ΔS/ΔT), the film of the present invention has a ratio of 1.5 or less, preferably 1.4 or less, and more preferably 1.3 or less. In comparison, the commercially available barrier shrink film (a7'+ (bt), which will be described later), had values of 2.8 and 1.9, respectively.
It is in the relatively low temperature range of ℃, and the maximum value is at least 1
009r skin, preferably 1252/ML, more preferably 140 P/j♂, which, in combination with the above-mentioned shrinkage rate, exhibits the characteristics of providing a sufficiently tight and tightly drawn package.

The fact that the shrinkage temperature is low and the stress value is high and the temperature is low is a disadvantage when processing the film, which is a packaging material, at an excessive temperature that exceeds the MP of the main mold combination that it consists of, which deteriorates the film (melting In addition to providing great benefits such as being able to package products without causing any problems (due to deorientation, deorientation), and preventing deterioration of various properties (strength, sealing strength, optical properties, etc.), when the packaged item is raw meat etc., the quality of the meat juice may deteriorate due to boiling. It has the great effect of preventing quality deterioration due to (drip) generation, etc., and its advantage is that it leaves thick marks.

In addition, since both properties are well balanced, excellent packaging products without wrinkles can be produced.

One of its other features is that it is excellent in cold resistance and has an ASTM D 1709-7 rating! The falling weight impact strength at 5℃ measured according to 'T is 150 mm in 60μ conversion
cm or more, preferably 170 Kg-an or more. Commercial product (a) (bJ is 1304-t's,
In the example below, where the value was 145Kt-equipment, it was 2.
There is one with a value of 30Kf/reliance. The reason why the film of the present invention is superior in this value is that all the layers are sufficiently cold-stretched and given a high degree of distribution.
It has also been found that normally the PVD layer has the poorest cold resistance, and the film breaks down from there, but the film of the present invention is at a strong level due to the synergistic effect of all the layers, which allows for unlimited distribution. It seems to be. In addition, the intensity is so high that it is difficult to measure using normal methods, so the following method was devised.

In other words, even when a missile with a film notch effect having a groove with a jagged edge in the falling weight was used to clearly show a significant difference during the same test, the film of the present invention, for example, Example RunNn 1 at -30°C, was used. Compared to the film of 67 Kf-cm, the film of
aJ, (b) is 25.27 at 4 cm.

This film has been found to be particularly strong.

This relationship will become clearer with reference to FIG.

Furthermore, one of the most important features of the film of the present invention is that it has low-temperature shrinkability and, at the same time, excellent high-temperature heat resistance and oil resistance.

The measurement method is to make a sample of 10 lengths by sealing a sealed film, that is, a 15 m wide center part with a thickness of 60 μm, in the shape of palms together, and apply enough lard on both sides of the central sealed part to the specified thickness. Lower the lower sample piece and dip the seal in a water bath at a specified temperature. Record the time it takes for the seal to be eroded by the hot oil (lard) and break, and it will not break for more than 60 seconds. We adopted a method of understanding the load to be maintained in relation to temperature. According to the method, it was found that the film of the present invention has a value of 100F/15m width or more, preferably 150F/15m width or more even at a temperature of 95°C. bJ's film has a poor oil resistance of 3.20Si/15th width, but this value is particularly excellent. When vacuum packaging meat and then shrinking it to improve its appearance, or when sterilizing it at the same time, the seal can be safely sealed without tearing the bag, and the tight shrinkage allows drips (gravy juices) to be removed. This is an important factor that means that it can be packaged while preventing the occurrence of such problems, and this is proof that the film of the present invention is particularly excellent in these properties. It becomes clearer.

Furthermore, one of the greatest features of the film of the present invention is that it has excellent optical properties before and after shrinkage. It not only has excellent optical properties at the initial stage of shrinkage, but also excellent after shrinkage, especially at high shrinkage rates. In other words, the rate of change in, for example, the HaZe value with respect to the shrinkage rate is generally small. This value is, for example, the HaZe value after 10% contraction, which is 15! X or less, preferably IOX or less. What is even more important is the value after high shrinkage in practical terms, and during actual packaging, there are many high shrinkage areas such as edges, free areas, clips, seals, and wrinkled areas. Of course it happens.

Also, if the packaged item is small compared to the size of the packaging film -
Practically speaking, this is often the case - in such cases, ordinary commercially available films have the drawback of causing the aforementioned whitening phenomenon, which significantly impairs the appearance. City 1) i'(a).

(b, 50!X Haze value at 40%, 80%
becomes. Also, at 60X contraction, the limit value is 80
It reaches ~90% and completely turns white. The value for the film of the present invention is expressed as a 50% yield, preferably less than 40, more preferably less than 35%.

As described above, the present invention has been able to reach an unprecedented level of excellent optical properties due to the synergistic effect of all the layers.

Here, we attempted to analyze the bleaching phenomenon and found that PVD
In addition to the fact that the surface layer other than the layer is rough from the beginning or becomes rough during shrinkage, the main reason for this is that the aforementioned zigzag bending of the PVD layer (zigzag whitening phenomenon) occurs and this is transferred to the surface. It has been clarified that this is a phenomenon in which there is columnar reflection at the interface between layers, and the interface is peeled off.

The reason for this is that the higher the shrinkage temperature of the film is, the steeper the shrinkage gradient, the lower the softening point of the film itself, regardless of the thickness or thinness of the polymer layer constituting the adjacent layer. m
The lower the p is, the lower the intermediate suspension, and the lower the PVD layer (DSC
) The higher the mp, the lower the PVD layer distribution rate (lower stretching degree, higher stretching temperature, resin-related factors, etc.), the more likely the PVD Jfi and adjacent layers will cause peeling phenomenon when left at room temperature. It turns out that this phenomenon is more likely to occur. Needless to say, if this occurs, in addition to the above-mentioned optical properties, the sealing strength, oil resistance strength, interlayer peeling phenomenon, and other strengths will be greatly reduced.

A more detailed investigation revealed that commercially available products (aJ has a shrinkage rate of 43 at 90°C)
It became clear that the zigzag whitening phenomenon suddenly occurred in X1 commercially available product (BL) after the shrinkage rate was 40% at 85°C.

Moreover, as a result of microscopic @ observation, it was seen that it had occurred in some places even before that. Compared to the above, an example of the film of the present invention Run
1, the above phenomenon did not occur. All of the above Haze values are values converted to 60μ, and this does not apply when the thickness is greater than this, or when it is colored, post-processed, enhanced, or laminated if necessary.

Furthermore, the film of the present invention has a high tensile strength (ASTMD88
It usually has a breaking strength of over 5% l m Jd (measured according to 2-67) and preferably has a strength of at least 7/&.

In addition, the film of the present invention can be sealed in a bag-like shape for one purpose, and can be used under severe conditions such as vacuum packaging with oil and fat attached and shrinking at high temperatures. It is often used in Therefore, it must have excellent oil resistance.

The film of the present invention has excellent bundling properties (sealing properties with clips) during vacuum packaging, and is characterized by less vacuum recovery due to pinholes during bundling, and this is the result of the synergistic effect described above.

Next, one example of a method for manufacturing a film made of the combination of polymers of the present invention will be described in detail, but the method is not limited thereto.

In the method of the present invention, the above-mentioned polymer compositions are thermoplasticized and melted using separate extruders, if necessary, and usually extruded through a multilayer gouer to obtain a raw fabric.Although other methods may be used if necessary, liquid refrigerant is used immediately after extrusion. It is preferable to obtain a sufficiently uniform tube-shaped original fabric that is rapidly solidified at 20° C. or lower.

The obtained ABC layer, PVD layer, and at least 4 layers of original fabric including 8 layers are heated to 100°C or lower, preferably 90°C or lower, more preferably 85°C or lower, and even more preferably ABC
Without melting the main crystalline components in the layers and 8 layers, the crystal components are rapidly cooled and heated to a temperature that does not impair the constant properties, and
℃ or less, preferably 35 to 80℃, more preferably 35℃
Sufficient internal pressure at a temperature of ~70°C below the melting point of the original crystalline component that is the main component of each composition of the above layers, more preferably below the Picat softening point of the main original polymer or mixture. For example, a desired film can be successfully obtained for the first time by expanding it into a bubble shape under a pressure of 100 to 3000 m water column. The optimal areal stretching ratio at this time varies depending on each composition and layer composition temperature at that time, but is generally 5 to 20 times, preferably 7 to 15 times. is generally 2 to 6 times, preferably 2 to 4 times. At this time, it is particularly important that the composition and layer combination be within the ranges mentioned above to prevent banks and allow sufficient cold stretching, and at the same time, it is important to form a sufficiently uniform raw fabric.

The degree of stretching is based on the speed ratio of the feed nip roll and the take-up nip roll, and the stretching ratio between the vertical directions is determined by the law.The only thing left to do is to fill the bubbles with soybean gas and draw the bubbles near the end of the process ((/
-, the maximum diameter is defined as the extent to which the chrysalis extends to the white hole of the B 0 layer and stops expanding laterally.

Deflating the film with a roll-type deflator immediately within a few minutes is the most stable method to carry out the stretching. Further, in view of the internal pressure and the diameter, it is convenient for the original fabric bubble to be as large as the diameter of 30 mm or more, preferably 50 mm or more as the device allows. In addition, due to the physical properties of the resulting film, it is preferable to stretch as long as possible with optical cooling as long as the stability of the bubbles allows, but in reality, the composition at that time must be adjusted depending on the balance with stability (to avoid puncturing). The degree of stretching may be determined by

In addition, the overall thickness of the film is increased evenly and stably by the 414th power effect in which each layer is stretched to the upper thighs, in addition to the characteristics of the wooden method, which allows for little heat exchange.
This results in a film having Yf.

Compared to the above, this problem does not occur in the normal stretching method in which the temperature is heated above the melting point. Nara'
/', i < , the self distance becomes more and more dense, and the strong J power also decreases. However, not only will the optical properties not be more favorable, but in addition, in the case of mixed compositions, the raw fabric will be subject to particularly brittle temperature conditions, which may lead to punctures, making it difficult to impart high properties. In particular, when combining different types of resins in multiple layers, the maximum stretching temperature of each resin is different, and in many combinations it is impossible to stretch all the layers. is often sacrificed.

It is not in the name of the present invention that the stretching referred to in the present invention can be successfully achieved in all layers at a cryogenic temperature, for example, 47°C, as in the later-described embodiments of the present invention; This is achieved for the first time by using a tube, a skewer using a uniformly quenched raw material, and a prior 11th power effect that satisfies conditions such as a specific stretching method. In addition, the stretching temperature in the present invention refers to the temperature at which stretching begins at 0,000 minutes, and naturally from there to the temperature at which stretching ends. is cooled and the temperature decreases from 10. In the end region of stretching (the region where the maximum diameter of the twigs is reached), it is preferable to sufficiently cool the film to at least 40° C. or lower, preferably 30° C. or lower, and more preferably 25° C. or lower. Therefore, it is preferable that the temperature difference between the beginning and end of the stretching is at least 5 cWJ, preferably at least 10°C, more preferably at least 15'C. For example, in the case of Run NQ8 in the example, the temperature at the stretching start point was 5.
At 4°C, the temperature was 50°C in the area where the bubble maximum diameter and the original fabric were expanding, and the temperature was 39°C in the % area, and 25°C in the end area. From the above, it can be seen that the method of the present invention is an unprecedented cold stretching method.

The following examples are given to illustrate the invention.

Example 1 Vinyl acetate group content (VAc): 5.5 mol%, melt index (MI): 1.0, crystal melting point (mP)
=88°C, Vicat softening point (Vs p ): 7
20Cz Ethylene acetate bimyl copolymer (EVA)
: a, : 60 parts by weight and a thermoplastic ethylene-α-olefin copolymer distomer (α-olefin is a random copolymerization of 15 mol% propylene and 2 wt% ethylidene-norbornene, MI: 0.45, density 0.88 fi
'/忤3, V sp: 40°C or less):b,:2
0 parts by weight, crystalline polypropylene (melt flow rate = MFR near, 0, density: 0.89P, / 3, ethylene ψ 4 wt 'A copolymerization, Vsp: 143 ° C.): cl: 2
Mixed composition (Vicat softening point 67°C)
) A B C, 1, employment, LLDPI (MI:
2.0, density: 0.915 tlCd, mp:
116. There is a peak at 120°C, Vsp: 98oCα-
Surface layer resin S is made by copolymerizing 3.5 mol% of octene-1 as an olefin, and vinylidene chloride copolymer (copolymerized with vinyl chloride, DSCSC) is used.
Beak mp is 145'C): 100 parts by weight, V
A c40wt% EVA: 2 parts by weight, epoxidized soybean oil: 1 part by weight Acetyltributyl citrate): 0
．． A PVD composition (PVDl) containing 5 parts by weight of P
As the resin for the VD layer, 5 layers of 3 types were individually thermoplasticized using 3 extruders, and these were fused in a gui and extruded at an average resin temperature of 190°C, followed by 5 layers from the tip of the die. At that point, quickly cool with cold water at about 8℃ and fold: 120mm, thickness =
A tube-shaped original fabric of 650 μm each with uniform thickness accuracy was created for each layer, and the layer structure was as follows from the outside of the tube:
S, = 60 μl AB C111 = 130 μ/PVD
,=100μ/ABC,,,=300μ/S,=6
An original fabric having a thickness of 0μ was prepared.

These raw fabrics are passed between two pairs of feed nip rolls and a faster take-up nip roll, heated between them to 47'C with hot air, and air is continuously introduced inside to expand them vertically. 3.1. After stretching with good stability to a width of 3.5 times, the area at the end of the stretching was cooled with an air ring blowing cold air at 15°C, folded with a roll-type deflator, and pulled with a 7" o-, roll. The sample was taken and wound up as it was to obtain a predetermined film.

At this time, in order to perform cold high-stretching smoothly, a rectifying contact guide is used to substantially isolate the heated part and the stretching start part, and a rectifying contact guide is used to entrain the surface of the original fabric and/or the film being stretched. While discontinuously contacting and removing the fluid and its boundary film in the circumferential direction, if necessary, the same contact guide is applied to the bubble part during stretching to create a substantially independent temperature-controlled air chamber and the stretching is continued. By creating stepwise temperature-controlled air chambers on the film and performing zone control, it was possible to carry out extremely stably.

The obtained film was 5.5 μ/12 μ/
9.2μ/27.8μ15゜A tubular film with a total thickness of 60μ at 5μ Run 1゜Next, the films shown in Table 1 were obtained by changing the thickness of each layer with the same layer structure -Run 2
~ (However, from now on, it will be referred to as the first layer from the outer surface layer).

Table 1 However, Run ratio -1 is a comparative example, and the raw fabric composition ratio is 180μ/30μ/110 when expressed in the same manner as above from the first layer.
μ / 30μ / 300μ I obtained a total of 650μ original fabric and tried to stretch it in the same way, but the result was a puncture at the initial stage of blowing up by introducing air into the tube, and I was unable to stretch it at all and could not obtain a product. Table 2 shows the values of the properties of these obtained films and two commercially available films as comparative examples. The results of examining sexual stability revealed that almost no changes were observed, confirming good stability.

However, here, the commercially available sample of comparative example ■ is 16μ/1
0 fi/ 34 /J Te total 6C1; EVA/P
This is a barrier/shrinkback for raw meat packaging with a VD/crosslinked EVA layer structure. The boil xylene insoluble gel in the crosslinked layer was 50 wt%. Also, VAc of EVA
was 9.5 wt%.

The commercially available sample of Comparative Example (2) is a barrier/shrinkback for raw meat packaging having a layer structure of 15μ/1μ/8μ/1μ/65μ, a total of 6oμ: nomer resin.

All of the films obtained above have excellent optical properties, low-temperature shrinkability, and various strengths, and as a practical packaging test, Run
The films of No. 1, Comparison ■, and Comparison ■ were immersed in hot water for a period of time under the respective conditions and shrink-wrapped. Items wrapped in Run 1 film are 75-8
Warm water at 0°C removes wrinkles and creates a tight finish with a ratio of 93.
It is finished within a narrow range of ~950C, but whitening phenomenon occurs in some areas. The appearance of the packaged products was the best for Ruri 1, followed by ratio ■, and then ratio ■. Also, if these objects are cooled to OoC and dropped from a height of 1 to 7L, Run 1. The bag of the item did not break even after being dropped 10 times, but the bag of the ratio ■ broke once and the case of ratio ■ broke after three times. 0 again
After storing it at ~5oC for a month, I observed that it was Run.
The first one seemed to have less dripping and was of excellent quality.This seems to be due to the fact that it can shrink at low temperatures and does not leave wrinkles on the surface, and the color changes when opened. Modoshi was the best.

Also, cut a commercially available ham in half, make blocks of approximately 1.3 to 9, and vacuum pack them tightly with each piece of film (15 mm due to extra dimensions).
%) When immersed in warm water containing 98'C crude oil, the surface layer of the sample peeled off in about 3 seconds, and the seal immediately peeled off and broke, and the sample sample peeled off in about 3 seconds, and the seal part of the sample peeled off in about 10 seconds. se
In step c, the surface layer melted and peeled off, causing the seal to break, but with the film of Run No. 1 of the present invention, the above phenomenon did not occur even after 5 minutes, and it had excellent oil resistance and shrinkability. I have proven that I am. Also, when each film was cut into 10 x 10 pieces and soaked in lard at 60°C, the lard penetrated through the cut portions of the films marked ■ and ■ after 30 and 40 minutes, respectively. A delamination phenomenon occurred, but no delamination occurred in the films of Run NO.i to B. This is because oil penetrates through a layer with insufficient oil resistance and a layer with insufficient interlayer adhesion at the cut end, causing a peeling phenomenon.

Example 2 In the same manner as in Example 1, predetermined original fabrics were prepared using 94 types of 5-layer dies, as necessary, to obtain films having the layer configurations shown in Table 6. The stretching temperature was 55, 59, 60, 56, 62 °C for Runs 7 to 11, respectively; 58, 61, 60, 67, and 420 °C for Ratio 2 to Ratio 6, respectively.
However, for ratios 2 to 5, the thickness of the original fabric is displayed in () in the table.

Resin type Os2- Linear low density polyethylene (MI:1
．． 0. Density: 0.917 S'1013. mp:
11B'C, Vsp: 102oC) Os3- Linear low density polyethylene (MI: 5
．． 5. Density: 0.920P10s3. mp: 1
Vsp99oC)O with a peak at 18°122°C
84-Linear low density polyethylene (MI: 2.0
．． Density: 0.9245'/cl! 1. mp:121'
CeVsp: 112℃) Os5- Linear low density polyethylene (MI: 2
5. Density: 0.919P/att', mp:12
1'C, Vsp: 95℃) Os6- Linear low density polyethylene (MI: 6
, Density: 0.9354/忤3+mp: 124°C.

v8p: 118℃) OS7-High pressure method/low density polyethylene (conventional LDPE not called linear) (MI: 2.0. Density: 0.919 tloyl
, mP: 105°C]088-Medium, low pressure process/high density polyethylene (normal HDPK) (MI: 1.0.Density '0.95'OS'/Os3.
m p: 132°C) OABC-EVA (VAC: 4.1 mol%, MI1
1: 1.0, mp: 95oC, Vicat:
78°C): O2: 65 wt%, ethylene-α olefin elastomer: b, (described above): 20 wt%.

IPP:C1: 15wt%f mixture + 7) Vsp is 6
4'C oABC, , -1-EVA:a, :55wt'A,
zfv α olefin elastomer: BL: 15wt
%, engineering PP: C1: 30 wt% and Vsp of the mixture is 70
oC Q ABC2:, +S2- above ABC211 near 0w
t% and the following S'30wt'A (7) mixture fVs
P is 70℃2・' ABC112-EVA: a,: 45 wt%
, ethylene-α olefin elastomer: b, :
15wt%.

Crystalline polybutene-1: (MI: 2.0. Density 0.9
jOt/Os3. Vsp, : 105oC, modified with 5 mol% ethylene, mpllooC
): C2: 40 wt% mixture, Vsp is 84'
C o ABCl, 2+C, -EVA: a,: 45
wt%, ethylene-α olefin elastomer: b,:
20 wt%, crystalline polybutene-1: C2:15 w
t% and IPP:C1: 20 wt'A (7) mixture f
Vsp is 3oC oS9EVA: O2 (described above) oPvD2 - 91 parts by weight of epoxidized soybean oil per 100 parts by weight of vinyl chloride IJ-density copolymer (copolymerized with vinyl chloride and has a DSC peak temperature of 142°C) Acetyl tributyl citrate = 1 part by weight + V A c
40% by weight of EVA: Composition O8 with addition of 2% by weight. -8,=70 wt% mixed with 30 virt% O2 The properties of the resulting film are shown in Table 4.

Although Run Na 7 to 11 were all able to stably achieve cold stretching, those with Ratio 2 were prone to punctures during bubble-up at the initial stage of stretching, and stable stretching could not be achieved. Even if the stretching temperature was as low as 40°C or as high as 95°C, vertical streaks were likely to occur and sufficient stretching could not be achieved.

The ratio 3 has the same tendency as the ratio 2, but the elongation is <<
, and was prone to punctures.

The one with a ratio of 4 was unstable but seemed to be able to bubble up to the point of stretching, but it still tended to leave streak-like thickness unevenness and puncture. This tendency shows that when the temperature is increased in the same way as above, the whole becomes whiter and more opaque.
It was easy to get punctures and could not be stretched sufficiently.
-Ratio 5. When I tried to put air in the puzzle, it immediately punctured, and the size was 30 to 95.
It was not possible to stretch it at all between .

With a ratio of 6, stretching could be continued continuously at a stable and sufficiently low temperature of 42°C.

Example 3 Using the same table method and layer combination as in Example 1, the copolymer of the vinylidene chloride copolymer layer was made to have an mp value of 14 at the DSC peak.
1.149,154 each temperature °C sequentially Runm12.13.
14, and 135°C1160°C ratio Run
As for No. 7 s 8, stretching was carried out under the same conditions. At that time, the one at 141,149° and 154°C was successfully and stably stretched, but the one at 135'C did not stop elongating and was unstable during stretching. It was prone to punctures. Also, 1
The one at 60oC was difficult to fully stretch and was brittle and prone to punctures, but when a partial sample of Run 8 was evaluated at the same time, Run No.
, 12+13.14 has optical characteristics as Run No.
Although there is not much difference from No. 1, the one with a specific Run m of 8 caused a remarkable zigzag whitening phenomenon even at a low shrinkage rate. Other heat shrinkage properties are good, but the specific Run No.
8 has insufficient shrinkage at 70°C ~ 10%, 80°C ~ 1
5%, the same stress is as low as 6DfP/w 2, and the fracture strength is 4.3 to 9/snow and -30c'C with the above-mentioned edge.
The missile impact strength was as low as 2 in 40.

On the other hand, the others showed excellent values, which may be due to the PVD layer.Also, the oxygen barrier performance was shown in Run12e13,14, and the ratio R
When shown in order as un 8, it is 43.19.12.8CC/Tr
It was L2 day II atm.

Example 4 A film was obtained by stretching in the same manner as in Example 1, using a vinylidene chloride/vinyl chloride copolymer having a peak of mp 150° C., using the same layer structure as in Example 1, and changing the additives of the PVD layer. . However, in the case of ratio Run 11, the 1.3rd layer is VA
C28% EVA 6-layer film, ratio Run
In the case of No. 12, EVA with a VAc of 18 wt% was used in each case, and the thickness ratio was 20.
μ/10μ/30μ.

Run No. 0.15 to 20 is Run 1 of Example 1.
No particularly inferior phenomena were observed, and the characteristic values were at a good level without much difference. Compared to the above, the ratio Run9.10
Ratio 11. was easy to puncture, but stretching was relatively smooth. In the case of the ratio 12, the original fabric was particularly susceptible to blocking and unstable, and good stretching could not be performed.
In No. 10, the layer adjacent to the PVDC layer used a special mixed composition that was oil resistant, so the area between the eyebrows tended to peel off after a while after stretching. The films with Nos. 11 and 12 were sticky and easily blocked, and had no stiffness. When examining the change in barrier properties over time, those with Runs 15 to 20 showed almost no change even after being left at room temperature for 15 days, at approximately 23 eC/77L2・da.
y-atm (23℃), but for ratios 9 and 10, immediately after
5Qec became 120CC, ratio 11.12
Then, the immediately after was 145CC, but it was 90cc, 9sec.
All of them were at a bad level.

When contracted over time, the ratio Run9.10. ．． 11, 12
Zigzag whitening occurred in both cases, and it was particularly severe in the case of 11.12, and the shrinkage ratios of Run 11 and 12 became soft and sticky, making them difficult to put into practical use.

Also, the shrinkage stress of the one with a ratio of 11.12 is: 40°50P/
wm2, and in the oil resistance test of the seal part, it peeled off instantly even under a 5fr load.

Comparative Example 1 A raw film was obtained in the same manner as in Example, and the layer structure of the raw film was adjusted and stretched so as to obtain a film having the composition and layer structure as shown in Table B below.

Table 6 ■ □□□□−□−” However, a5-EVA (VAc: 10.3 mol%
, MI: 4) The film with a ratio of 13 has a zigzag whitening phenomenon during shrinkage, and the film with a ratio of 14 has poor processing stability during stretching, and is easily banked. <Crystallization occurs during stretching because the PVD layer is too thick. It is difficult to remove heat, and when measuring the physical properties of a small sample, it was found that the low-temperature shrinkability was decreased, resulting in a decrease in both sealing performance and cold resistance.

It was difficult to stretch the film with a ratio of 15, and when air was introduced into the bubble to make it bubble up at 40 to 70°C, it was immediately punctured and could not be stretched at all.

In addition, as the stretching temperature is increased, it gradually swells, and at 80°C, the blow-up ratio is about 2, and it is finally possible to continue with the sushi remaining, and at 85°C, the blow-up ratio is 3.5, and it becomes slightly swollen. Although it was unstable and swayed, it was possible to continue stretching, and at 910C, it was finally possible to continue stretching stably. This film is whitish and has poor optical properties (haze value 25%), and low-temperature shrinkage is 70.80.
5.12% at ℃ and 32% at 90℃, 95% respectively.
It is of the type that only shrinks at a high temperature of 41% at °C, and the shrinkage stress is as low as 90S'/tie2. In addition, the zigzag whitening phenomenon of the PVDC layer is 30
There was a tendency for this to occur when shrinkage exceeded %. Oil resistance was 60 JFr at 95°C. Also, the stretching temperature was set to 95
, 100° C., the deterioration of optical properties and the decrease in low-temperature shrinkability tended to become more severe. Furthermore, the stability of the bubble was also on the decline. Further, if the temperature was increased beyond this point, only a thin, white, and non-uniformly thick film could be obtained in some areas.

The one with a ratio of 16 was punctured at each temperature and could not be stretched.

[Brief explanation of the drawing]

FIG. 1 shows the film of the present invention and a commercially available film (a). This diagram shows the temperature dependence of the shrinkage rate with (b).
-1 is the film of the present invention (Run No. 1)
1-2 is the above-mentioned commercially available film (a); 1-3 is the above-mentioned commercially available film (b). FIG. 2 shows the dart impact strength of the film of the present invention, a comparative sample, and commercially available films (a) and (b) (the grooved edge mentioned above was adopted) as a function of the measurement temperature. In the figure, 2-1 is the film of the present invention (RunNn1)
2-2 is the ratio Run Nα6 2-3 is the above-mentioned commercially available film (a) 2-4 is the above-mentioned commercially available film (b). FIG. 3 shows the high temperature oil resistance of the film of the present invention, comparative samples, and commercially available films (a) and (b). In the figure, 3-1 is the film of the present invention (Run No. 1). 3-2 is the ratio RunNα6; 3-3 is the above-mentioned commercially available film (a); 3-4 is the above-mentioned commercially available film, etc.). Applicant Asahi Dow Co., Ltd. Agent Yutaka 1) Yoshio Figure 2 Temperature ('C) Procedural Amendment February 4, 1980 Commissioner of the Japan Patent Office Shima 1) Haruki Tono 1, Case Indication Patent Application 1982- 200861 No. 2, Title of the invention: Low-temperature heat-shrinkable multilayer barrier film and its manufacturing method 6, Person making the amendment Relationship with the case Patent applicant: Asahi Dow, 1-1-2 Yurakucho, Chiyoda-ku, Tokyo (046) Co., Ltd. Representative Kado 1) Yoshi Yu 4, Agent Room 204, Sanshin Building, 1-4-1 Yurakucho, Chiyoda-ku, Tokyo Phone: 501-2138 Toyota Naigai Patent Office 5 Explanation” column 6, contents of amendment 1) “Polyethylene,” on page 16, line 9 of the specification, has been changed to “
Corrected to ``polyethylene layer''. 2) "Mere resin alone" on page 13, line 10.
6) Correct ``a single layer of mer resin'' to ``a single layer of mer resin'', 6) Same as No. 1
In the first line of page 7, "Usually 0.2 to 1.0 and preferably" is corrected to "Usually 0.2 to 10 and preferably." 4) "It is 75 to 95 mol%." in the 18th line of the 19th line of the same page is changed to "75 to 85 mol%." 7,” he corrected. 5) r (VA c : 10.3 mol%, MI: 4) J in the 1st line of page 67 of the same page is r (VA c : 10.3 mol%, MI: 4゜mp
Near 3°C, Vsp: 43°C)” is corrected.

Claims (1)

[Claims] (1) The material is a copolymer of ethylene and a monomer selected from vinyl ester monomers, aliphatic unsaturated monocarboxylic acids, alkyl nistyl monocarboxylic acids, or linear At least one polymer selected from low-density polyterene, (Bl is a soft mono-lastomer with a density of 0.9197 cm or less consisting of a tyrene-alpha niolefin copolymer, (Ct is crystalline polypyrene, crystalline polybutene) -1
or a mixed polymer thereof; and the above (
8) At least 11@ of a mixed composition (ABC) layer consisting of BJ and +CI was measured using the DSC method at a place with a thickness of 35 to 5% in the total layer thickness. A barrier layer made of vinylidene chloride copolymer (PvD) with a crystal melting peak in the range of 140 to 155° C. is coated adjacent to the barrier layer, and a linear low-density polyethylene (1-ethylene chloride) selected from the above is coated on the surface layer. ], L'DPE) at least one resin (S) layer composed of a bundle with a total thickness of 2 to 25μ and a ratio of 5 to 40% of the total layer thickness. and has a heat shrinkage rate of at least 15.25% at 70.80°C, and a maximum value of shrinkage stress of at least 100S'/&I7. Shrinkable multilayer barrier film. (2) Polymer (A+ has vinyl ester group content: 2 to
The multilayer barrier film according to claim (1), which is an ethylene-vinyl acetate ester copolymer having a melt index of 12 mol and a melt index of 0.2 to 6. (3) Polymer (AJ is a copolymer of ethylene and at least one monomer selected from the group consisting of acrylic acid, acrylic acid, methacrylic acid, and ethyl methacrylate; The multilayer barrier film according to claim (1), wherein the car body has a content of 2 to 12 mol %. (4) The car body (A) is made of linear low density polyethylene, and has a melt index of 0. 2~10゜Density: 0
．． 910 to 0.935 P/cl, 1 te multilayer barrier film according to claim (1). (5) Polymer (AI is linear low-density polyethylene, and ethylene has a carbon number of C5 to C such as propylene, butene 7, pentene, hexene, heftene, octene, 4-methyl-1-pentene, etc.) '+2
(6) The multilayer barrier film 0 according to claim 11 or (4) is a copolymer of at least 7 mol % or less of at least one type of onfin selected from α-olefins. , ethylene 93 mol% or less, 40
The multilayer barrier film according to claim 1, wherein at least mol% of α-olefin and yne are copolymers selected from propylene, butene-1,4methyl-1-pentene, and the like. (V
The multilayer barrier film according to claim 1 or 6, which is a soft-ga copolymer having an icat softening point of 80 C or lower. A multilayer barrier film according to claim 1, which is a polymer. (9) The specific mixed components forming the mixed composition layer are 0 in weight ratio.
．． 90≧A/(A+B+'O')≧0.20.0.50
≧B/(A+B+O)≧0.05, Q, Ft O≧C
/ (A+B+a)≧0.0F) The multilayer barrier film 0 according to claim (1)
□0 units) The specific mixed components forming the mixed composition layer have a weight ratio of 0.80≧A / (A + B + Cj)≧
0.25, 0.40≧B/(,A+B+C) conflict o,!
o, 0.4! 'i≧C, / (A + B10)≧
τ11 of the patent claim which is 0.10 (1) or (9)
The multilayer barrier film Oυ as described in Section 1. Mixed set & (ABC) layers are adjacent to both sides of the barrier (PVD) layer, and further, as a surface layer (linear low density polyethylene (LLDPE) selected from AJ) on both sides.
% 1% barrier film according to claim (1), comprising at least five layers of resin (S) mainly composed of: O2 high temperature oil resistance strength is at least 100f/IF at 95℃
The multilayer barrier film according to claim 1, which has a width. (131 (8j is selected from a vinyl ester monomer, an aliphatic unsaturated monocarboxylic acid, a copolymer of a monomer selected from the monocarboxylic acid alkyl ester and ethylene, or a linear/low density polypropylene) at least 1
Kinaka's chassis body, (B+ is a combination of L Karen-α type reflex and a soft elast with a density of 0.919/011 or less (C1 is either crystalline polypropylene, crystalline polybutene-1, or a mixture thereof) The polymer is vinylidene chloride having a mixed composition Pj (ABI) consisting of the above-mentioned (AJ, (BJ and system copolymer (PVD), and the linear low-density poly, x Chile 7 (LLDPE selected from AJ)
) are respectively melted and kneaded, and at least one of the (ABC) layers is coated with (PVD).
4 or more layers of tubular raw fabric with 6 layers adjacent to the ) layer and 1 or less (S) layer on the surface are extruded from a multilayer gouer and rapidly solidified with a liquid refrigerant. As it is or heated to 100℃ or less, and stretching temperature 30~
Cold-stretched at a temperature range of 90°C at an area stretching ratio of 4 times to 30 times, the PVD layer has a thickness of 35 to 5X among the total thicknesses, the (S) layer has a thickness of 2 to 25μ, A method for producing a low-temperature heat-shrinkable multilayer barrier film, which comprises obtaining a stretched film having a thickness of 5 to 40% of the total layer thickness. (141) The method for producing a multilayer Paryani film according to claim 03, wherein the stretching temperature is in the temperature range of 35 to 80°C. (15) The poly-II-G! Manufacturing method. (1b) All layers are cold-stretched at a stretching temperature of 35 to 70°C below the Vicat softening point of the main resin constituting each layer, imparting cold-stretching properties to all layers. Claim No. 031, (141) A method for producing a multilayer barrier film as defined in any one of paragraphs (15) and 17. The original fabric and/or
Alternatively, a substantially independent temperature-controlled air chamber is created by discontinuously contacting and removing the fluid accompanying the film surface during stretching and its boundary film, and then the film is stretched and stretched to reach its maximum diameter, and at the same time, a deflator is applied. A method for producing a multilayer barrier film according to claim 03, which is carried out by deflating.