JPH0324951A - Multi-layer polymer film - Google Patents

Abstract

PURPOSE: To obtain excellent oxygen barrier properties in a wide extent of humidity conditions by a method wherein the ratio of the incremental water vapor transmission rate between a first layer of an ethylene-vinyl alcohol copolymer and an outer surface of a film through a layer of a vinylidene chloride copolymer interlaid to the water vapor transmission rate between the first layer and the other surface of the film is made specified. CONSTITUTION: A multilayer polymer film 210 has a first layer 212 of an ethylene-vinyl alcohol copolymer, a second layer 214 of a vinylidene chloride copolymer and a third layer 216 of an adhesive interposed between the first and second layers, and the water vapor transmission rate(WVTR) between the first layer of EVOH and a first outer surface of the film through the VDC copolymer interlaid is made lower than the WVTR between the EVOH layer and a second outer surface of the film being off from the VDC copolymer. The ratio between the WVTR from the VDC to the first surface and the WVTR from the VDC to the second surface is made ordinarily about 0.25/1 or below.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a polymer film. In more detail,
The present invention relates to films that provide excellent oxygen barriers. The present invention is particularly directed to films that will be exposed to moisture at some point during their expected service life. (Prior art) Ethylene vinylanoleanolecopolymer (BVO
}l) is known to act as an oxygen barrier in multilayer films. It is also known that vinylidene chloride copolymer (VDC) exhibits oxygen barrier properties. However, the oxygen barrier properties of VDC and HVOH copolymers are affected differently by the humidity of the environment in which these polymers are used.
VOC copolymers have relatively poor oxygen barrier properties compared to BVOH copolymers with low ethylene content (and in some cases higher ethylene content), but are relatively less sensitive to humidity changes.

In other words, the oxygen barrier properties of the V[lC copolymer under high humidity conditions are approximately the same as those under low humidity conditions. Although the oxygen barrier properties change to some extent as the humidity changes, these changes is not very large. EVO}I with low ethylene content is V at low humidity.
It is a much better oxygen barrier than DC. EVO}I, which has a high ethylene content, has a certain V at low humidity.
Provides a better oxygen barrier than DC copolymers. However, EVOH copolymers are quite sensitive to the humidity to which they are exposed; at high humidity, for example above about 75-80%, the oxygen barrier properties of EVOH decrease and become inferior to that of VDC copolymers. ．． In other words, at humidity above about 75-80%, the EV
The oxygen permeability of OH is usually higher than that of VDC copolymers. The oxygen permeability values discussed herein are based on comparing 1 mil EVOH copolymer to 1 mil DC copolymer, unless otherwise specified. Therefore, while EVOtl with lower ethylene content is generally preferred for use in low humidity environments, vOC copolymers are generally considered more suitable for films exposed to high humidity environments.

EVOH copolymers with high ethylene content have somewhat higher oxygen permeability than EVOH copolymers with low ethylene content or some DC copolymers. εVOH copolymers with high ethylene content have intermediate moisture sensitivity. in general[! For conventional use, EVOH copolymers with high ethylene content are preferred in some cases because VOH copolymers are easier to process than VDC copolymers.

However, in order to obtain the barrier properties provided by vDC copolymers while avoiding the high oxygen permeability of EVOH copolymers in high moisture environments, v
The usual method is to use DC copolymers. On the other hand, in cases where low humidity conditions are expected to be maintained on the outside of the packaging, low ethylene content EVOH with low oxygen permeability is generally preferred to increase shelf life.

One disadvantage of this method is that packaging containers that are exposed to high humidity only during their useful life have traditionally used barrier layers of VOC copolymers, and therefore by using an EVOH copolymer rather than a vDC copolymer, the packaging container During the useful life of the EVO}I copolymer, the packaging container benefits from the low ethylene content of EVO II with low oxygen permeability when the relative humidity is low enough to allow the EVO II copolymer to reap the benefits. The reason is that it is not possible. Therefore, it is necessary to produce a film that provides an excellent oxygen barrier for EVOH at low humidity, and whose oxygen barrier properties are not easily affected by changes in humidity, and in particular, are not easily affected by high humidity. is desirable. Indeed, it would be desirable to create a film that has the advantage of the lower oxygen permeation rate of low ethylene content EVO}I at low humidity, yet has the advantage of a more stable oxygen barrier provided by the VDC copolymer at high humidity. .

The present invention therefore provides a multilayer polymer film that combines a low oxygen permeability at low humidity comparable to that provided by EVOH copolymers and an oxygen permeability at high humidity typically comparable to the barrier provided by VDC copolymers. The purpose is The films of the present invention are advantageous in that they can provide the barrier properties of VDC copolymers at all times, yet provide the superior properties of iVOH during periods when humidity is, for example, below about 75%. The present invention provides multilayer polymeric films with good oxygen barrier properties over a wide range of humidity conditions. According to the invention, a multilayer polymeric film comprises a first layer of ethylene vinyl alcohol copolymer, a second layer of vinylidene chloride copolymer, and a third layer of adhesive preferably interposed between the first and second layers. The adhesive layer has an adhesive layer that provides an adhesive force (as measured by peel strength) of at least about 100 grams per inch of width to at least one of the vinylidene chloride copolymer layer and the ethylene vinyl alcohol copolymer layer. Typical compositions for the third layer of adhesive include EVA with a high vinyl acetate (VA) content (particularly with a VA content of 15
% or more of EVA), blends and copolymers of polypropylene, homopolymers or copolymers with EVA (PP), ethylene methyl acrylate (E?IA)
), anhydride-modified polypropylene, homopolymer or copolymer (MPP), and anhydride-modified ethylene vinyl acetate (M[!VA). Additionally, in a preferred embodiment, water vapor permeation between the EVOH first layer and the first outer surface of the film via V[lC cobolylue is provided.
i! Level (WVTR) between EVO II layer and VDC:
7 between the polymer and the second outer surface of the film - lower than the VTR. Typically, one V from vDC to the first surface
The ratio of TR to WVTR from the VOC to the second surface is approximately 0.
．． It is less than 25/1. Preferably, the film of the present invention includes a fourth layer of sealant, wherein the second layer of vinylidene chloride copolymer is EVO.
I+11th t! and the fourth layer of sealant.
Preferred compositions for the sealant layer are selected from the group consisting of olefin-based polymers, copolymers and blends thereof.

Typical sealant layer systems for high temperature applications include polypropylene homopolymers, polypropylene copolymers, and polyethylene having a resin density of at least about 0.940 (preferably at least about 0.950). Typical sealant layer &
[Some materials include EVA, low density polyethylene (L
DPE), medium density polyethylene (?IDPE), ionomers, and linear low density polyethylene (t.
) etc., a fifth layer of adhesive may be disposed between the second layer of VDC copolymer and the fourth layer of sealant. Representative materials useful in the fifth layer composition include EVA copolymers containing greater than about 15% vinyl acetate, blends of PP and EVA, and copolymers EAA, MPP, and EVA. One particular example of a film of the invention includes a first layer comprising EVO}I, a second layer comprising EVA containing greater than about 15% vinyl acetate, a third layer comprising VDC copolymer, and a third layer comprising vinyl acetate. Mention may be made of a polymer film having a fourth layer comprising EVA containing about 15% or more and a fifth layer comprising LLDPE in the above order. Other specific examples of films of the invention include a first layer comprising EVOH, a second layer comprising anhydride-modified polypropylene,
A multilayer film having a third layer comprising a VDC copolymer, a fourth layer comprising an anhydride-modified polypropylene, and a fifth layer based on polypropylene, in the above order. Yet another specific example of a polymer film of the invention is E
A first layer containing VOH, a second layer containing an anhydride-modified EVA copolymer, a third layer containing a V[lG copolymer, a fourth layer containing an anhydride-modified EtlA copolymer, and LLDPI! a fifth layer comprising, in the above order. In some implementations B of films of the invention, a single adhesive layer is disposed between the EVOH layer and the vDC copolymer layer [! Preferably, the adhesive layer is in surface-to-surface contact with the VOH layer and the VDC layer such that the adhesive layer imparts a bond strength to the first and second layers of at least about 100 grams per inch of width. In one series of films of the present invention, the film is:
A coextruded multilayer film having an 11th FJ comprising a vinylidene chloride copolymer and a 2nd FJ coextruded with the vinylidene chloride copolymer and comprising an ethylene vinyl alcohol copolymer. The coextruded film is v
One layer of DC copolymer and EVO}! Preferably, it includes an intermediate adhesive layer as described above disposed between the layers. In one embodiment a of the invention, the VDC copolymer comprises a vinylidene chloride vinyl chloride copolymer. In other embodiments, the preferred copolymer is vinylidene chloride methyl acrylate copolymer. With respect to making the films of the present invention, one manufacturing method for the film is to coextrude the EVOH and vDC copolymer, forming the EVOH into a first layer having an annular shape at a first humidity; forming the VDC copolymer into a second layer having an annular shape at a second humidity that is significantly lower than the first humidity; combining the first layer and the second layer into a multilayer film; and coextruding and cooling the film; forming the EVOH copolymer at a first humidity of about 380°F (19
3°C) to 420°F (216°C) is preferred.
Preferably, the VOH:7 polymer layer and the vDC copolymer layer are coextruded through a single coextrusion die and formed into a ring in substantially the same amount of time. Another preferred method of making the multilayer polymeric films of the present invention includes the steps of: processing a first &[l bottom containing EVOH in a first extruder to produce a first melt stream.
processing a second at-product comprising a VOC copolymer in a second extruder to produce a second melt stream;
And the first one! A polymer material capable of bonding in the molten state to at least one of the I component and the second All component is processed in a third extruder to produce a third melt stream to form a third melt stream in the solid state. At least about 100g per inch
It includes the steps of providing an interfacial peel strength of . The first melt stream, the second melt stream, and the third melt stream are then fed to a coextrusion die (an annular die or a linear die). The melt streams are combined in the die, with a third melt stream interposed between the first and second melt streams. Subsequently, the combined melt streams are processed into a multilayer film in a die, extruded from the die as a coextruded film, and then cooled. The present invention provides a multilayer packaging material that collectively defines a packaging container, wherein said packaging material includes a first layer comprising EVOH and a vOC copolymer disposed between said first layer and the article. 2N), an article within a packaging container, and an environment for the outer surface of the packaging material that has a lower humidity than the humidity at the inner surface of the packaging material. In packaging materials,
The increment 11VTR between the EVOH No. 11J and the first surface of the packaging material via the vDC copolymer is 'EVOH
i and the second surface of the film away from the VDC copolymer is less than the increment WVTR. The packaging material in such a packaging system includes a heat-sealable fourth layer between the article and the DC copolymer second layer, and a heat-sealable fourth layer between the vDC copolymer layer 21'W and the heat-sealable fourth layer. a fifth layer including a second bonding layer;
Preferably, it contains IW. A preferred composition for the fourth layer comprises LLDPE and a preferred composition for the fifth layer comprises an EvA copolymer. However, in some embodiments, the fourth layer comprises a propylene-based polymer composition and the fifth layer comprises a carboxy-modified propylene-based polymer. Furthermore, especially when the heat-sealable fourth FJ includes LLDPE, the third
and the fifth bonding layer may include anhydride-modified EVA.
With respect to certain embodiments of packaging systems of the invention made using coextruded films of the invention, the packaging system comprises a coextruded multilayer thermoplastic film, an article within said film as part of the packaging system. , and an environment for the outer surface of the film that has a lower humidity than the humidity at the inner surface of the packaging material. This film is [!
a first layer comprising a VOR, and a second layer comprising a VDC copolymer disposed between said first layer and the article.
It has layers. For packaging containers that will be exposed to high humidity during the expected service life of the packaging container, the -VTR between the first EVOH layer and the inner surface of the film will be reduced by the second layer of the film away from the EVOH layer and the vDC copolymer. It is important that it be smaller than -VTII between the (outer) surface and the gap. Regarding the preparation of the film of the present invention, the EVOH first layer and the VDC
Preferably there is a third layer of adhesive polymeric material between the second layer. The invention can also be described as a method of manufacturing packaged articles. The first step of the method consists of selecting the appropriate materials and layer structure and fabricating the multilayer polymer film. The film has a first layer comprising an EVOH copolymer, a second layer comprising a vDc copolymer, and a second layer comprising a vDc copolymer.
a WV between the EVOH first layer and at least one outer surface of the film via the VDC copolymer, with a third bonding means interposed between the first layer and the second layer;
The TR is less than the -VTR between the EVOH layer and the second outer surface of the film remote from the vDc copolymer. Following the creation of the polymeric film, the process includes converting the film into a packaging container using a second outer surface of the film (with an E disposed toward the outside of the packaging container).
water vapor can most easily permeate from the V O 11 layer to the second outer surface of the film); and positioning the article in a packaging container, wherein the article is inside the packaging container and outside the packaging container. Ensure that the water concentration is higher than the surrounding water. The prepared packaging container is then hermetically sealed together with the moisture or moisture contents.
In such packaging, the layer of VDC copolymer acts as a moisture barrier to protect the EVO}I from moisture within the packaging, thereby preventing moisture within the EVOH and between the EVOH and the outer surface of the packaging. The moisture in between will permeate to the outer surface faster than it permeates through the VDC copolymer to the EVOHFJ and from there into the surrounding low humidity environment.

Therefore, the moisture content of EvOH copolymers is generally more representative of the ambient moisture conditions outside the packaging than the moisture conditions inside the packaging. The smaller the ratio of -VTR to the inside of the packaging container to one VTR to the outside of the packaging container, the more the EVOH will fit and more closely represent the moisture conditions on the outside.

A low HVTR ratio (e.g., about 0.25/1 or less, preferably about 0.15/I, more preferably about 0.05/1
The packaging containers of the present invention allow EVOH to represent the ambient moisture conditions of the external environment, allowing them to be processed through a high moisture environment (e.g. retort autoclave) and subsequent low moisture environments (e.g. retort autoclave). for example, the surrounding atmosphere). In films made in this way and treated by the process described above, the packaging film absorbs moisture from the high moisture environment and subsequently transfers that moisture, particularly between the EVOH copolymer and the outer surface of the packaging container. of water is released into a low moisture environment against the outer surface of the packaging container. The result of these processes, which also include moisture absorption and moisture release, is that as the packaging film absorbs moisture and recovers to the level of oxygen barrier provided by the EVOII copolymer as the film releases moisture into the low moisture environment. , the oxygen barrier of the packaging film is reduced to the level of oxygen barrier provided by the vDC copolymer layer, which is less sensitive to moisture. 1 to 6 show cross sections of typical films of the present invention. Throughout the drawings, the first number in the number sequence represents the figure number and the second and third numbers represent the identified element. Regarding Figure 1, the 2FJ film is numbered 110
It is identified by In FIG. 2, the film as a whole (here a three-layer film) is identified by the number 210. Similarly, the third. Figures 4, 5, and 6 are identified by numbers 310, 410, 510, and 610, respectively. Each film of the present invention contains an ethylene vinyl alcohol copolymer as an essential constituent; 4. f. : 1st
layer and a second layer of vinylidene chloride copolymer. And in fact, the simplest form of the invention is one that includes only these two layers as seen in FIG. include. Although the 2N film of FIG. 1 is satisfactory as providing the desired properties in the film of the present invention (i.e., oxygen barrier properties that are relatively insensitive to humidity and moisture), preferred films provide additional desirable characteristics. It is a film with additional layers. Especially the first
Regarding the figure, it was found that the interlayer attraction between EVOHi and vocl was very small. Follow, EVOII layer 21
2 and the VDCFJ 214 is preferably provided with an adhesive layer 216. Typical adhesives useful for N16
Ii products have a VA of about 15% or more (usually about 18 to 38
%) contains EVA. Other typical adhesive compositions include blends or copolymers of EVA and polypropylene. Still other adhesives that can be used include EM^, anhydride-modified polypropylene, homopolymers or copolymers, and anhydride-modified ethylene vinyl acetate copolymers. The above-mentioned anhydride-modified material may have a copolymer as a constituent unit, or may be a blend of a modified material and an unmodified polymer material. Other suitable polymeric adhesives will be apparent to those skilled in the art of polymeric films. The film shown in Figure 2 was bonded to EVO II by adhesion JI16.
It is superior to the film of drawing No. 1 in that the adhesion between layer 12 and V[)C layer 14 is strengthened. To enable packaging containers to be made efficiently and economically using only the adhesive strengths inherent in the films of the present invention, the films preferably include a sealant layer 318 as shown in FIG. The film can be processed into packaging containers (e.g., vouchers) by heat sealing, which is applied to the periphery of the container. The composition of the sealant layer 318 is:
They are selected for their moisture tolerance as well as their suitability to integrate into the film structure. Accordingly, a typical sealant layer M for use at high temperatures (such as in retort structures exposed to processing conditions up to about 275 degrees Fahrenheit) is a polypropylene homopolymer or copolymer,
and at least about 0.940 (preferably about 0.9
A typical sealant layer set for low temperature use is a polyethylene-based Sealant N composition having a resin density of 50) EVA. LDP
E, MDPE. 7io / 7+, +hi approx. 0.89
There are LLDPEs, including those with a low density of 0. For high temperature applications, higher density LLDPEs may also be used in some cases.

Naturally, additives for modification can also be used as necessary. In this way, the film in Figure 3 is
EVOH (7) comprising a first layer 312, a second layer of VDC, a third layer of adhesive, and Sealan I [318]. In FIG. 4, the EVOH layer is shown as 412 and the vOC layer is shown as 414. The adhesive layer 416
and corresponds to adhesives N216 and 316 in FIG. layer 4
18 corresponds to sealant N318 shown in FIG. Layer 420 is an adhesive layer between VDC copolymer layer 414 and sealant layer 418 and is provided to improve adhesion between layers 414 and 418. The composition of adhesive layer 420 can be selected from among the materials previously described for the composition of adhesive layer 16. Therefore, typical materials include EVA containing about 15% or more of vinyl acetate, blends and copolymers of EVA and polypropylene, EMA, MPP, and lfEVA.
etc. The &ll materials of the contacts rfi 16 and 20 may be the same, and are preferably the same for structural simplicity, but different materials may be used for [16 & N20. It is particularly desirable that by selecting different adhesive materials for layers 6 and 20, the adhesion between corresponding layers is improved.

Adhesive layer 16 is used to provide adhesion to either EvouN 212 or vDC layer 214, or both. When adhesive layer 16 is bonded to only one of layers l2 and 14, adhesive FI 16 is in surface-to-surface contact with only that layer and then with other intervening layers between layer 16 and the other of layers 12 and 14. (not shown) in surface-to-surface contact. However, in preferred embodiment B, adhesive layer 6 is in surface-to-surface contact with layers 212 and 214;
Therefore, it is connected to layers 212 and 214. Contrary to this, the adhesive [420] may be in surface-to-surface contact with only one of the VDC layer 14 and the sealant layer 18, and thus bond to only one of the VDC layer 14 and the sealant layer 8. You can leave it there. In this case, the adhesive 1420 is
There is surface-to-surface contact with an intervening layer (not shown) between the N420 and the other of layers 14 and 1B. However, in this case as well, adhesive layer 420 is preferably in contact with both layers 14 and 18, and is therefore directly bonded to these two layers. The film of the present invention can be produced by various processes. These processes include steps such as extrusion, coextrusion, lamination, extrusion-lamination, and coextrusion-lamination. A preferred process for making the films of the present invention is a coextrusion process, which is also preferred from an economic standpoint. In a coextrusion process, all layers of the film are preferably extruded simultaneously through a single die.

Tube coextrusion can also be applied. However, a preferred process for efficiently making the films of the present invention is a cast coextrusion process, in which the composition of multiple layers is processed through a corresponding extruder to produce a melt stream, and then the melt stream is is sent to the coextrusion die. At the die, the melt streams are combined into a multilayer film that is preferably exposed from the die opening.
The polymer is then extruded onto chill rolls where it is cooled and solidified. FIG. 7 shows a five-layer film of the present invention (e.g. 41 in FIG. 4).
Equipment 724 used to co-extrude cast 0)
This is a diagram showing a combination of the following in the form of a block diagram. F
J412, 414, 416, 418, and 420
(N416 and 420 are the same set) to process four separate polymer sets,
728,729. and 730 are used. Extruder 72
6 processes EVOH for layer 12. Extruder 728
processes VOC copolymers for N14. Extruder 729 processes adhesive for layers 1G and 20. Extrusion [730 processes the sealant for layer 18. Melt streams 840 and 84 from extruders 728 and 729, respectively
2 (see FIG. 8) passes through connecting tubes 734 and 737 to a coupling adapter (shown dashed in FIG. 8) where adhesive is placed on either side of vDC melt stream 840. Combined with melt stream 842 3
A layered melt stream 848 is formed which is then sent to die 838. Melt streams 844 and 846 from extruders 726 and 730, respectively, pass through connecting tubes 732 and 736 directly to die 838. In the coextrusion die 38,
Melt streams 844 and 846 are combined with three-layer melt stream 848 to form a 5N melt stream, which is extruded from die 38. As the 5-layer melt stream is extruded from the die 38, the 5-layer melt stream is placed on a chill roll 8 where the 5-layer melt stream is held at, e.g., 90 degrees Fahrenheit.
50 and solidified here to form layers 812, 81
A film consisting of five layers, 4, 816, 818, and 820, is prepared. A film is made with a die,
After solidifying on chill roll 850, the film is wound or further processed according to conventional film manufacturing processes. 9 and 10 illustrate packaging containers that can be easily made using the films of the present invention, particularly those containing a sealant layer 18. The pouch 942 shown in FIG. 9 is typically made by placing two films in a surface-to-surface relationship with each other and providing a heat seal 943 around the periphery. Alternatively, it can be made by folding a portion of the sheet material with the corresponding sealant layer portions facing inward and forming a seal around the facing surfaces. Another example of a packaging container that can be made using the film of the invention is shown in FIG. Tray 104
No. 6 is formed by a thermal molding method from a sheet thicker than the film produced in the present invention. The thickness of the films of the present invention is about 1 to 25 mils, preferably about 1.5 to 10 mils. Films of preferred thicknesses have a high degree of flexibility and are therefore useful in a variety of flexible packaging applications. Although thicker films can be made,
This increases costs more than necessary to obtain the benefits of flexible packaging film. For the package shown in FIG. 10 (encircling the space 1045 between lower package members 1046 and 11010), lower package member 1046 has a thickness of 10 to 30 mm at the bottom of the tray. Preformed trays made from thicker material, such as by heat forming a 40 to 80 mil thick sheet to obtain a tray having a . This provides a tray with the degree of rigidity normally required in this type of packaging. 11010 of this packaging container is, for example, the first
This is the film of the present invention as shown in Figures 6 to 6. When making sealed packaging containers using the film of the present invention, one layer of sealant can be used to provide the seal. If a sealant layer is not present as part of the film IO, an additional adhesive material is used between the opposing surfaces to be sealed. Sealant layer 18
When used, portions of the opposing surfaces are brought into surface-to-surface contact when forming a seal between each opposing film portion. The vinylidene chloride copolymer used in the films of the present invention may be any commercially available vinylidene chloride copolymer, particularly those containing vinyl chloride or acrylate comonomers (particularly methyl acrylate). Vinylidene chloride vinyl chloride copolymers typically have an extrusion humidity of about 310-330°F, unlike regular ethylene vinyl alcohol copolymers, which have extrusion humidity in excess of 375'F. Therefore, when producing the films of the invention by coextrusion, a melt stream is formed in a corresponding extruder at the desired humidity and is exposed to the respective humidity only in the die. At least a portion of the die is maintained at a high temperature since high humidity is required for the EVOH to maintain fluidity in the die.
The VDC copolymer is exposed to at least a portion of the high temperatures required by EVOH as it passes through the die, and is processed into a multilayer film and extruded from the die along with other melt streams. EVOH is thus processed into a melt stream and ultimately into film form at elevated temperatures, e.g., 390-410"F. However, vinylidene chloride copolymers are processed at lower humidity (e.g., about 310-330"F). Processed into a melt stream.Of course!!VOH copolymers and V
The melt processing concentration of DC copolymer will vary depending on the type of copolymer being processed. For example, vinylidene chloride vinyl chloride copolymers are preferably processed at temperatures between 320 and 330 degrees Fahrenheit, and vinylidene chloride methyl acrylate copolymers are preferably processed at slightly lower humidity levels between 310 and 320"F. Important features of the present invention are , providing a suitable arrangement of layers when making a film, providing a suitable arrangement of layers when making a packaging container of the invention, and in particular, predicting for the outside of the packaging container. There is provided a packaging container containing an article that creates a humidity inside the packaging container that is higher than the humidity that exists in the ambient conditions at which the product is exposed. It is desirable to prepare a packaging container by arranging the film of the present invention so that vinylidene chloride copolymer N14 is interposed between the article and the ethylene vinyl alcohol copolymer.

In this arrangement, the vDC copolymer acts as a moisture barrier between the EVOH and the moisture inside the packaging container;
The incremental permeation of moisture from inside the packaging through the vDC copolymer layer and into the EVOH layer is controlled. It is further important that the barrier to moisture transmission between the EVOH layer and the outside of the packaging is substantially lower than the moisture barrier between the EVOH layer and the inside of the packaging. Therefore, in the packaging film of the present invention for use in moisture-containing articles, the layers located inside the EVOH layer have higher moisture barrier properties than the layers located outside the EVO II. In the film of the present invention,
Mainly VDC copolymer provides a good moisture barrier in the film. Therefore, when the humidity inside the packaging is higher than the humidity outside the packaging, the VDC copolymer is positioned in the packaging from the EVOH layer 12 towards the inside of the packaging. In Figures 1-4, EVOII is shown as the outer surface of the film for simplicity. And in particular, when producing the film of the present invention using a coextrusion method, the first to fourth
As shown, the EVOH is preferably the outer layer of the coextruded layers. However, when the film is made into a packaging container, it is preferred that a material that is highly resistant to abuse constitutes the outer layer of the film. Thus, a abuse-resistant material N522, such as polyethylene terephcrate (PET), polyamide, polycarbonate, etc., is applied onto the EVOHFJ 12 by means of an adhesive N523, such as a curable urethane adhesive. Naturally, the adhesive for N523 is the combination of layers 512 and 522 fff! It is selected by considering I.

FIG. 5 shows a representative 2.5 mil thick film of the present invention from which moisture barrier properties can be calculated.

To measure moisture barrier properties, adhesive layer 516,
520 and 523 all have a thickness of less than 0.1 mil,
shall provide a nominal incremental moisture barrier property. Therefore,
In evaluating moisture barrier properties, these contributions are ignored for simplicity; EVOHWI512 becomes the base layer from which incremental moisture barrier properties are calculated. Incremental moisture barrier is the barrier provided by the increment in film thickness. The increments chosen for comparison correspond to the thicknesses between corresponding layer interfaces. In this example, the EVOH layer 5
The thickness of 12 is 0.5 mil. The VDC copolymer is a 0.5 mil thick vinylidene chloride methyl acrylate copolymer (VDC-MA). Sealant F! 5
18 is a 1.0 mil thick LLDPε. The abuse-resistant layer is 0.5 mil thick PET. The moisture permeability outward from the EVOH is determined by the outer layer, the 0.5 mil thick PET layer, and is approximately 40 g/min at 60% relative humidity. The incremental moisture permeability inward from EVOI, which is
LDPE layer 518) speed combination. The combined speed is approximately t. 6 g/m" day. Therefore, the ratio of the incremental moisture permeability of the inner layer to the incremental moisture permeability of the outer layer is about 1.6/40 or about 0.04/1. In the above discussion: The thickness of EVOIIF! and vocl is 0.5 mil, and the total thickness of the two layers is 1.0 mil. When rearranging the thickness of the two layers so that VDC l is as thin as possible. , the thickness of the voc layer is approximately 0.
It is 1 mil. If EVOII is thickened so that the total thickness remains 1.0 mil, its thickness is 0.9 mil. In such a film, the incremental moisture permeability of the inner layer of EVOH is about 6 g/day. Also E
The incremental moisture permeability a4 degree of the outer layer of the VOH holds 40 g/m'' day. Therefore, in this case the ratio of the incremental moisture permeability of the inner layer to the incremental moisture permeability of the outer layer is about 6740 or about 0
．． It is 15/1. The ratio of the incremental moisture transmission rate of the inner layer to the incremental moisture transmission rate of the outer layer is less than or equal to about 0.25/1, preferably less than or equal to about 0.15/1, providing the desired excellent oxygen barrier with low sensitivity to moisture. In the case of preferred films of the present invention exhibiting a Furthermore, the overall WVTR for the entire thickness of the packaging material must be low enough to provide a stable moisture content of the packaged article, and the VDC layer must be 0.
For a 1 mil thick VDC-1'lA, when the outside relative humidity is about 60%, it typically lasts about 6g71 days or less. This is generally achieved by the moisture barrier properties of the VDC copolymer layer 14. Of course, depending on the film structure, the relative thickness of the layers, and the ambient conditions at the film surface,
Other substances also play a role in shaping the moisture barrier. By providing a high moisture barrier increment to the inner layer,
The film will have the ability to drain moisture from the EVOH layer to the low humidity environment outside the package faster than the moisture can permeate from the inside of the package to the EVOH layer. If the outer layer has relatively low moisture barrier properties, the humidity within the EVOH Jil 2 will be quite close to the humidity to which the outside of the packaging is exposed. Therefore, when the outside of the packaging container is exposed to high humidity, the EvOH layer absorbs moisture and the contribution of EVOH as an oxygen barrier is significantly reduced. However, VDC
layers are not affected much. The contribution of the V[lC layer as an oxygen barrier remains almost unchanged. In this way, the oxygen barrier properties of the packaging film are maintained at a level close to that provided by vDC copolymers. When low humidity is restored to the outside of the packaging container, it passes through several outer layers with low moisture barrier properties [! Moisture within the VOH is quickly discharged to the low-moisture outside environment. EVO
When the moisture in layer II is quickly discharged, the oxygen barrier properties of EVO}19 are restored accordingly. Figure 11 shows the oxygen barrier properties of EVOI1 copolymer and vinylidene chloride copolymer. All tests represent the oxygen transmission rate (OTR) of 1 mil thick films. As shown, the conventional vinylidene chloride vinyl chloride copolymer (VD(:-VC) is about 2.25 g/l
w” a (7) OTR, VDC-MA has an OTR of approximately 0.85 g/day. Figure 11 shows that the OTR of the VOC copolymer does not change significantly as the humidity changes. Figure 11 further shows that at low humidity the 0↑R of the εVOH film is lower than the OTR of some VDC films; however, at high humidity the 0↑R of the VDC film
This shows that it is higher than τR. For example, ethylene is 32
% OTI of E V O II? is the relative humidity (
R. I{. ) O% is about 0.15g/m'' day, but VDCMA's OTR is about 0.ll15t', V
[) C-11c no OTR Ha about 2.25 tares. However, about 75% I? ．． ll. In this case, the OH of the old VDC and the OTR of EVO II are almost at the same level. about 7
5%R, 11. Although EVOH's OTII becomes lower when exceeding 92%R. }I. Until v
oc-ve higher than no-org. As can be seen from Figure 11, the OTII of EVOH is affected by the ethylene content. εVOtl containing at least 40% ethylene has a V
OTII equal to or greater than OTR of DC-MA
has. However, still, the maximum is about 85-90%
R. lI. In some applications in which the films of the present invention may be used, the films are temporarily exposed to high humidity and high points (e.g., in a retort in a high temperature autoclave). The packaging film, including the EVOII layer 12, is removed from this treatment during the autoclaving process (usually steam or hot water is used), during which it is returned to a low-humidity and low-temperature environment after the process is completed (processing). Absorbs hot water or steam. Naturally, the absorbed moisture will cause the EVOH to become more susceptible to high temperature and humidity conditions.
The oxygen barrier properties of H decrease. However, VDC
Copolymer N14 is not significantly affected. In fact, the first
As can be seen from Figure 1, the VDC copolymer layer maintains approximately the same level of oxygen barrier properties in both dry and wet environments. Therefore, during autoclaving, the oxygen barrier properties of the film are generally reduced by the VDC copolymer layer 1.
It represents the oxygen barrier property of 4. After the autoclaving process is completed and the packaging container is removed from the high moisture environment,
The film is i:vOHii! 2 outwardly to the outer surface of the packaging container to release the moisture absorbed during the autoclaving process.

That is, the outer layer of the packaging container releases moisture outwardly from the EVOH layer into the low moisture surrounding environment. As moisture is released, and especially as moisture leaves the VOH layer 12, the M. of the EVOH layer l2 increases. The basic barrier properties are restored. Therefore, whenever the packaging container is in a low humidity environment, the oxygen barrier properties of the packaging container generally represent the oxygen barrier properties of EVOH at low humidity. There is a recovery period during the process when the EVOH, whether wet or dry, reaches equilibrium with the outside environment, and the oxygen barrier properties of the packaging are moderate.

Now, with regard to specific examples of films of the present invention, the following structures are representative of films having the desirable properties of films of the present invention. /EVO}l/EVA/VDC/EVA/LLDPE/
/EVOH/? IPP/VDC/MPP/PPE//E
VOII/Ml! VA/VO(:/MEVA/LLOP
E/IPET/urethane adhesive/EVO}I/MEVA
/VDC/? IEVA/LL[lP[! /Boribrobire of gate PP xanhydride modification/! 'lEVA. Anhydride modified ethylene vinyl acetate certain UN
BiL A four-layer film as shown in FIG. 3 was produced.

εv011 is a GL-ET with an ethylene content of 38% commercially available from Nippon Gosho. The tie layer 16 is Plexar 2965 (anhydride modified [!v^), 1114 is vinylidene chloride vinyl chloride copolymer. Layer 18 contains approximately 9% vinyl acetate.
It is a product containing EVA. The film was made by R-extrusion of the polymer in the production of a four-layer film. The humidity of εVOH entering the die was approximately 395@F. The humidity of the Brexer 2965 entering the die was approximately 350@F. The humidity of the VDC copolymer in the die was about 325°F, and the EVA containing II18 (71 humidity was about 360°F).
~400"F (7>). Several polymers were formed into tubular layers and the tubular tape was extruded through an annular die at a thickness of approximately 151". Samples of the tape were then heat formed and A tray of about 2 inches deep x 4 inches square was prepared. The thickness of the hot-formed material obtained was about 1.5 mm. The oxygen barrier properties of the obtained material are shown in Table 1. Table L Oxygen permeability, C gate 100χ 20.4 23.1
The oxygen permeability in Table 1 was determined by exposing the inner surface of the film to 100% humidity using an Oxtran Oxygen Analyzer. Then 50% of the outer surface of the film
The permeability of 1 g of acid was measured after exposure to 75% or IOO% humidity. By measuring the oxygen transmission rate when there is a moisture difference between two surfaces, packaging containers containing wet articles can be sylated and thus the performance of the film can be evaluated. The outside of the packaging container is then exposed to the low humidity (ie 50% or 70% relative humidity) of the outside surrounding environment. Similarly, when dry goods are packaged, placing the EVOH between the VDC and the goods provides an excellent oxygen barrier. In the case of heat-sealable packaging films, EVOHjil2 is interposed between the vDC layer and sealant N18. The film shown in Figure 6 is a typical example of such a film. In FIG. 6, layers 612, 614, and 616 each have an EV
Represents the OH layer, VDC layer, and intervening adhesive layer. Layer 618 is a sealant layer as shown in FIGS. 3 and 4. Layer 624 is layer 216, 31
6, and 416 as described above. Example 2 A fourth 5N film is produced by cast coextrusion. EvOH is Soarol D, commercially available from Nippon Goui. The ethylene content of Soarnol O is 29%. The vDC copolymer of layer 14 is Dow 119 vinylidene chloride methyl acrylate copolymer. Vinylidene chloride copolymers contain conventional heat stabilizers. Sealant layer L8 is Dow 3010 normal fjtm density polyethylene. Both adhesives 7116 and 20 are Brexer 326 (anhydride modified EVA). It's inside the die < [! The humidity of both the VOH and LLDPE melt streams is approximately 400°F. The humidity of the adhesive breaker 326 entering the die is approximately 320°F. The humidity of the Dow 119 vinylidene chloride methyl acrylate copolymer entering the die is approximately 315°F. These materials were combined in a die to create a multilayer film as shown in FIG. The thickness of the film extruded from the die is about 2.6 mm, gvOHI'l
The thickness of the VOC copolymer layer is about 0.3 μl, and the thickness of the VOC copolymer layer is about 0.6 μl. The thickness of the bonding layer of plexer 326 is approximately 0.1 mil, and the thickness of the LLDPH is approximately 1.5 mil. The oxygen permeability of the film thus produced was examined within the relative humidity range described in Example 1. Use EνOH[ on the low humidity side, V
DC copolymer is EVOH and moisture i! If we consider the film as something intervening between the VOC copolymer and the film, we can obtain an oxygen permeability as shown by the actual value V in Figure 12. When the film arrangement is reversed so that EVOl1 is interposed between II (III), the oxygen permeability becomes the first
It will look like “B” in Figure 2. Curve “C” in Figure 12 is
Figure 2 shows the calculated oxygen permeability of a single layer with the same Soarnol D EVOI and the same thickness as the EVQH layer in the film of Example 2 (i.e. 0.3"S). Therefore, Figure 2 shows that the EVOH When directed towards the inside of the packaging container (which is simulated by the 'K humidity side of the oxygen tester), the oxygen permeability will be reduced by any humidity present relative to the other surfaces of the film (i.e. by the outside surface of the packaging container). be relatively constant at (expressed humidity);
And the oxygen permeability is 0.6 mil thick VDC-? IA
This indicates that the oxygen permeability of the copolymer layer approaches the iIA degree. When the EVOH is placed towards the outside of the packaging container, i.e. when the VDC copolymer is placed between the EVOII layer and the article, the EVOII absorbs moisture into a low density ambient environment (i.e. about 75% R. H. that the oxygen permeability of the film will be lower than that of the VDC copolymer and is rather controlled by the excellent oxygen barrier properties of εVO}I. Curve "A" shows. Therefore, packaging H (
When the vOC copolymer is properly placed between the EVOI (and the article) and the EVOH is able to leach moisture into the outer environment adjacent to the packaging container, a low humidity (e.g. as shown in Figure 12) It has the advantage of EVOH's low oxygen permeability (below about 75%!?.H.), yet does not have the high oxygen sensitivity characteristic of films where εv011 is the sole source of oxygen barrier. ．． Rather, its maximum oxygen permeability is controlled by the VDC copolymer so that it never exceeds the level of oxygen permeability associated with the corresponding VDC copolymer at the thickness of use. Example 3 Films were coextruded as in Example 2 with appropriate adjustments to melt processing humidity for different polymers. Layer l2 is EVOH. Layer 14 is vinylidene chloride methyl acrylate copolymer. N16 and layer 2
2 is QF-500 anhydride-modified polypropylene commercially available from Mitsui Petrochemical. N418 is a propylene ethylene copolymer. Example 4 A film was produced in the same manner as in Example 3. Nl
2 is εI/O}I. rr114 is vinylidene chloride methyl acrylate copolymer. Layer 18 is linear low density polyethylene. 116 and layer 20 comprised an ethylene vinyl acetate copolymer containing about 28% vinyl acetate. EXAMPLE 5 [As in Example 4, except that the composition of 14 was a vinylidene chloride vinyl chloride copolymer. A film was created. Example 6 A film was produced in the same manner as in Example 4. Adhesive layers 16 and 20 are both 0.1 mil thick.
EVO}I contains 32% ethylene, the thickness of layer 12 is 0.51 Lt', VDC is VDC-? With IA, the thickness of layer 14 is 0.5 mil. Sealant layer 18 is LL[lPR and has a thickness of approximately 1.0 mil. A 0.5-wall thick PET film was bonded to the HVO}I layer using a curable urethane adhesive to produce a 7-layer film as shown in Figure 5. Example (Comparative) 6 2.5 mil as in Example 6 except using 0.5 mil VDC-MA and 0.5 mil E'fOl{ in place of adhesive layer 16. A film was produced. With EVO II on the low humidity side, the oxygen permeability across the entire film thickness was calculated for the film of Example 6 and the film of Example (comparison) 6, and is shown graphically in FIG. Curve "D" represents the film of Example 6.
Curve "E" represents the film of Example (Comparative) 6. As can be seen from the graph, both films have excellent oxygen barrier properties of about 0.2-0.3 at low humidity.
Although both curves increase with increasing humidity, the degree of increase of curve "D" is smaller than that of curve "E", indicating that the film of Example 6 is less affected by increasing humidity. That is, at 1002 relative humidity, the OTI? of the film of Example 6? is only about 1.6, but the OTR of Example (Comparative) 6 is about 18. The extent to which the objects of the invention are achieved will vary somewhat depending on the choice of V[lC and EvOH copolymers, the thickness of the several layers, and the humidity to which the film is exposed.
Therefore, the OTR of the selected EVOH layer is 0% LL
(preferably at 50% R.l!) than the OAR of the layer of VDC copolymer selected. Typical OT for 1 mil thick film
R is shown in Figure 11 for EVOH (with varying ethylene content) copolymers and different VDC copolymers. I! By selecting a certain combination of VOR and VDC copolymers and by suitably defining the corresponding layer thickness, the OTII of the EVOH layer at low humidity is
(lower than the OTR of the IC layer), improved OTR over the OTII of a similar film using VDC at low humidity and over the OTR of a similar film using EVOH at high humidity. Naturally, the actual layer thickness obtained by extrusion can be varied close to the desired thickness, and its accuracy is limited by the precision of the film manufacturing equipment used. The larger the difference in OTH between the Eν011 layer and the Vale layer, and the wider the humidity range, the higher the EVOH in the same film.
The advantages of combining the i and VDC layers will become even greater. Therefore, 0%! ? ．． H. At least 25% of
R. lI. (preferably in the range from O% 11.1+. to at least 50% R.Il.) [tVO
} Preferably, the combination of EVOH copolymer and vDC copolymer and the layer thickness are selected such that the OTII of one layer is lower than the OTR of the VDC layer. Therefore,
When used in combination with VDC-MA, the ethylene content of EVOH should typically be about 40% or less, with the thickness of the EVOH and VDC layers being equal. However, E containing 40% or even 44% ethylene
VOH (see Figure 11) is connected to VIIC as VDC layer.
-Additional benefits can be imparted to the film when used in combination with VC or in layers with a thickness greater than that of the corresponding VDC layer. Is this OTI? This is because it changes not only depending on the polymer composition but also on the layer thickness.

However, at high humidity, the maximum OTR of the film is almost determined by the νDC copolymer, so <EVOI+ can be selected without considering OTR at high humidity. Rather, it is necessary to consider the OTH of EVOHMi plants at low humidity (in this case,
The OTII of the film is almost determined by the OTII of the VOH). Therefore, preferable EVO}I is, for example, 28 to 3
Low 0τR at low humidity with 2% ethylene
It is an extrudable 1g composition with a low ethylene content, giving . As described above, the excellent oxygen barrier properties of εVOH are usually fully exhibited at low humidity, and the oxygen barrier properties of VDC copolymers, which are not easily affected by humidity, are fully exhibited at high humidity. Since the highest oxygen permeability of the film is generally controlled by the oxygen permeability of the VDC copolymer, it is advantageous to select a VDC copolymer with a relatively low oxygen permeability.
Among commercially available VDC copolymers, those containing methyl acrylate comonomer are generally superior to those containing vinyl chloride comonomer (see Figure 11). Therefore, copolymers made using methyl acrylate as a comonomer are preferred for the films and packaging containers of the present invention, in which case oxygen permeability is a factor in selecting the vDC copolymer.

Accordingly, the present invention provides a new film and a new packaging container that have excellent oxygen barrier properties and whose oxygen barrier properties are less affected by moisture, as well as a method for producing such films. Various modifications may be made to the compositions and structures of the films and packaging containers of the invention, as well as to the methods of making the films and packaging containers of the invention, without departing from the spirit of the invention. should be obvious to those skilled in the art. Although the present invention has been described by citing preferred embodiments,
It is obvious that the present invention is capable of many modifications, and it goes without saying that all such modifications are included within the scope of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of the two-layer film of the present invention. FIG. 2 is a diagram showing a cross section of the 3N film of the present invention. FIG. 3 is a cross-sectional view of the 411 film of the present invention. Figures 4 and 6 are cross-sectional views of the five-layer film of the present invention. FIG. 5 is a cross-sectional view of the seven-layer film of the present invention. FIG. 7 is a diagram showing the general arrangement of extrusion equipment for producing the film of the present invention. FIG. 8 is a cross-section of the die of FIG. 7, a film cooling device used in combination with the extrusion device of FIG. 7, and a cross-section of a five-layer film being produced in the die; FIG. 9 is a diagram showing a pouch produced using the film of the present invention. Figure 10 shows half a liter! FIG. 2 is a cross-sectional view of a packaging container with a lid made using the film of the present invention, with the container being shaped from a tray to packaging. FIG. 11 is a graphical representation of the relative oxygen permeability of representative BVOH and vDC copolymers. FIG. 12 shows the oxygen permeability of the film of the invention and the corresponding l! VO! lF! Figure 13, which is a graph showing a comparison of the oxygen permeability of a single layer film of EVOI'l with L This is a graph showing the advantages of the former when compared with the produced films of the same thickness.

Claims (1)

[Claims] 1. (a) a first ethylene vinyl alcohol copolymer;
(b) a second layer of vinylidene chloride copolymer; and (c) interposed between said first and second layers, at least 100 grams per inch of width of at least one of said first and second layers. A third layer of adhesive that imparts adhesive strength with peel strength, where the composition of the third layer of adhesive is an ethylene vinyl acetate copolymer containing 15% or more of vinyl acetate, or a blend of polypropylene and ethylene vinyl acetate copolymer. and a copolymer selected from the group consisting of ethylene methyl acrylate copolymer, anhydride-modified polypropylene, and anhydride-modified ethylene vinyl acetate copolymer;
the ratio of the incremental water vapor permeability between the layer and the outer surface of the film through the vinylidene chloride copolymer layer to the water vapor permeability between the first layer and the other surface of the film is about 0.25. /1 or less. 2. The composition of the third layer is selected from the group consisting of ethylene vinyl acetate copolymer containing about 18 to about 35% vinyl acetate copolymer, anhydride modified ethylene vinyl acetate copolymer, and anhydride modified polypropylene. , the multilayer polymeric film of claim 1. 3. The multilayer polymer film of claim 1 or 2, wherein the film includes a fourth layer of sealant, and the second layer of vinylidene chloride copolymer is interposed between the third layer and the fourth layer of sealant. 4. The multilayer polymer film of claim 3, wherein the composition of the sealant layer is selected from the group consisting of linear low density polyethylene, polypropylene polymers, polypropylene copolymers, and polyethylene having a resin density of at least 0.940. 5. A fifth layer of adhesive is included between the second layer of vinylidene chloride copolymer and the fourth layer of sealant, wherein the composition of the fifth layer is ethylene vinyl acetate containing about 15% or more of vinyl acetate. 4. The multilayer polymer film of claim 3 selected from the group consisting of copolymers, blends and copolymers of polypropylene and ethylene vinyl acetate copolymers, ethylene methyl acrylate copolymers, anhydride modified polypropylene, and anhydride modified ethylene vinyl acetate copolymers. 6. A fifth layer of adhesive is included between the second layer of vinylidene chloride copolymer and the fourth layer of sealant, wherein the composition of the fifth layer is ethylene vinyl acetate containing about 15% or more of vinyl acetate. 5. The multilayer polymeric film of claim 4 selected from the group consisting of copolymers, blends and copolymers of polypropylene and ethylene vinyl acetate copolymers, ethylene methyl acrylate copolymers, anhydride modified polypropylene, and anhydride modified ethylene vinyl acetate copolymers. 7. (a) a first layer comprising an ethylene vinyl alcohol copolymer; (b) a second layer comprising an ethylene vinyl acetate copolymer containing at least about 15% vinyl acetate; (c) a third layer comprising a vinylidene chloride copolymer. (d) a fourth layer comprising an ethylene vinyl acetate copolymer containing about 15% or more of vinyl acetate; and (e) a fifth layer comprising a linear low density polyethylene; polymer film. 8. (a) First layer comprising ethylene vinyl alcohol copolymer; (b) Second layer comprising anhydride modified polypropylene; (c) Third layer comprising vinylidene chloride copolymer; (d) Anhydride modified and (e) a fifth layer based on polypropylene; and (e) a fifth layer based on polypropylene; and (e) a fifth layer based on polypropylene. b) a second layer comprising an anhydride modified ethylene vinyl acetate copolymer; (c) a third layer comprising a vinylidene chloride copolymer; (d) a fourth layer comprising an anhydride modified ethylene vinyl acetate copolymer; (e ) a fifth layer comprising linear low density polyethylene; a multilayer polymer film comprising the following layers in the above order. 10. The multilayer polymeric film of claim 1, wherein the third layer of adhesive is in surface-to-surface contact with the first and second layers, thereby interconnecting the first and second layers. . 11. The film includes a fourth layer of sealant;
11. The multilayer polymeric film of claim 10, wherein the second layer of vinylidene chloride copolymer is interposed between the third layer and the fourth layer of sealant. 12. (a) processing a first composition comprising an ethylene vinyl alcohol copolymer in a first extruder to produce a first melt stream; (b) a second composition comprising a vinylidene chloride copolymer. (c) directly bonding in the molten state to the surface of at least one of the first and second compositions to form a width in the solid state; (d) processing a polymer composition capable of providing an interfacial peel strength of at least 100 grams per inch in a third extruder to produce a third melt stream; and feeding said first, second, and third melt streams into a coextrusion die; (f) processing said combined melt stream into a multilayer film in said die and extruding said multilayer film from said die; and (g) said coextruded melt stream. A method for producing a multilayer polymer film, comprising the steps of: cooling the film. 13. The method for producing a film according to claim 12, wherein the vinylidene chloride copolymer is a vinylidene chloride vinyl chloride copolymer. 14. Claims 1 and 7, wherein the vinylidene chloride copolymer is a vinylidene chloride memel acrylate copolymer.
9. The polymer film according to any one of 8 and 9. 15. The polymer film of claim 3, wherein the vinylidene chloride copolymer is a vinylidene chloride methyl acrylate copolymer. 16. The polymer film of claim 4, wherein the vinylidene chloride copolymer is a vinylidene chloride methyl acrylate copolymer. 17. The polymer film of claim 5, wherein the vinylidene chloride copolymer is a vinylidene chloride methyl acrylate copolymer. 18. The polymer film of claim 6, wherein the vinylidene chloride copolymer is a vinylidene chloride methyl acrylate copolymer. 19. The polymer film of claim 10, wherein the vinylidene chloride copolymer is a vinylidene chloride methyl acrylate copolymer. 20. The method for producing a film according to claim 12, wherein the vinylidene chloride copolymer is a vinylidene chloride methyl acrylate copolymer. 21. A packaging system comprising a multilayer packaging material and an article in the packaging system, wherein the packaging material comprises a first layer comprising an ethylene vinyl alcohol copolymer, located between the first layer and the article. a second layer comprising a vinylidene chloride copolymer bonded thereto, and a third bonding layer between the first layer and the second layer, wherein the environment for the outer surface of the packaging material is an incremental water vapor permeability between the first layer of ethylene vinyl alcohol copolymer and the outer surface of the film through the layer of vinylidene chloride copolymer, the first layer having a humidity lower than the humidity at the inner surface of the film; and the other surface of the packaging system, wherein the ratio of water vapor permeability to the other surface of the packaging system is about 0.25/1 or less. 22, comprising a fourth heat-sealable layer between the article and the second layer, a fifth layer between the second layer and the fourth heat-sealable layer comprising a second bonding layer; 22. The packaging system of claim 21, comprising: 23. The packaging system of claim 22, wherein the fourth layer comprises linear low density polyethylene and the fifth layer comprises ethylene vinyl acetate copolymer. 24. The packaging system of claim 22, wherein the fourth layer comprises a propylene-based polymer composition and the fifth layer comprises an anhydride-modified propylene-based polymer composition. 25. The packaging system of claim 22, wherein the third and fifth tie layers include anhydride-modified ethylene vinyl acetate and the fourth heat-sealable layer includes linear low density polyethylene. 26. A packaging system comprising a coextruded multilayer thermoplastic film and an article in the packaging system, wherein the film comprises a first layer comprising an ethylene vinyl alcohol copolymer, and the first layer and the article a second layer comprising a vinylidene chloride copolymer disposed between said ethylene vinyl alcohol copolymer and an environment relative to said outer surface of said film having a lower humidity than said humidity at said inner surface of said packaging material; The ratio of the incremental water vapor permeability between the first layer and the outer surface of the film through the vinylidene chloride copolymer layer and the water vapor permeability between the first layer and the other surface of the film is about 0. .25/1 or less. 27. The packaging system of claim 26, wherein the film includes a third layer of adhesive polymeric material coextruded between the first and second layers. 28. Claim 26 or 2, wherein the vinylidene chloride copolymer comprises a vinylidene chloride vinyl chloride copolymer.
7. The packaging system according to 7. 29. Claim 2, wherein the vinylidene chloride copolymer comprises a vinylidene chloride methyl acrylate copolymer.
6 or 27. The packaging system according to item 6 or 27. 30. (a) a multilayer comprising a first layer comprising an ethylene vinyl alcohol copolymer, a second layer comprising a vinylidene chloride copolymer, and a third tie layer interposed between said first layer and said second layer a process of making a polymer film;
At this time, the first ethylene vinyl alcohol copolymer
the ratio of the incremental water vapor permeability between the layer and the outer surface of the film through the vinylidene chloride copolymer layer to the water vapor permeability between the first layer and the other surface of the film is about 0.25. /1 or less; (b) processing the film into a packaging container with the film arranged so that the incremental water vapor permeability from the first layer is greater toward the outside than the inside of the packaging container; and (c) hermetically sealing the container, whereby the vinylidene chloride copolymer layer acts as a moisture barrier to protect the ethylene vinyl alcohol copolymer from moisture within the container, and prevents moisture within the ethylene vinyl alcohol copolymer layer and between the ethylene vinyl alcohol and the outer surface of the packaging container. , moisture in the ethylene vinyl alcohol copolymer layer permeates to the outer surface of the packaging container faster than it permeates from inside the packaging container to the ethylene vinyl alcohol copolymer layer, such that moisture in the ethylene vinyl alcohol copolymer layer represents ambient moisture on the outside of the packaging container. ; A method for producing packaged articles, including the steps of; 31. The method of claim 30, wherein said film making step includes coextruding said first, second, and third layers. 32. The method of claim 30, comprising the step of selecting vinylidene chloride methyl acrylate copolymer as the vinylidene chloride copolymer. 33. Selecting a vinylidene chloride methyl acrylate copolymer as the vinylidene chloride copolymer, whereby the film making step includes the ethylene vinyl alcohol copolymer layer, the vinylidene chloride methyl acrylate copolymer layer, and the intervening third 32. The method of claim 31, comprising coextruding a tie layer. 34. The third layer of adhesive has at least 100 g of adhesive per inch of width to at least one of the first and second layers.
an ethylene vinyl acetate copolymer, a blend or copolymer of polypropylene and ethylene vinyl acetate copolymer, which imparts an adhesive force with a peel strength of g, at which the composition of the third adhesive layer contains 15% or more of vinyl acetate; 30 - selected from the group consisting of ethylene methyl acrylate copolymer, anhydride modified ethylene vinyl acetate copolymer, and anhydride modified polypropylene.
33. The manufacturing method according to any one of 33. 35, comprising passing the container through a high moisture environment and subsequently returning the container to a low moisture environment, wherein the film absorbs moisture from the high moisture environment and subsequently treating the container with the The moisture between the ethylene vinyl alcohol copolymer and the outer surface is released into the low moisture environment, thereby reducing the oxygen barrier of the ethylene vinyl alcohol copolymer as the film absorbs the moisture and causing the film to absorb the moisture. 3. Releasing the ethylene vinyl alcohol copolymer into the low moisture environment restores the oxygen barrier of the ethylene vinyl alcohol copolymer.
34. The manufacturing method according to any one of 0 to 33. 36, comprising passing the container through a high moisture environment and subsequently returning the container to a low moisture environment, wherein the film absorbs moisture from the high moisture environment and subsequently treating the container with the The moisture between the ethylene vinyl alcohol copolymer and the outer surface is released into the low moisture environment, thereby reducing the oxygen barrier of the ethylene vinyl alcohol copolymer as the film absorbs the moisture and causing the film to absorb the moisture. 3. Releasing the ethylene vinyl alcohol copolymer into the low moisture environment restores the oxygen barrier of the ethylene vinyl alcohol copolymer.
4. The manufacturing method described in 4. 37. A packaged article produced according to the manufacturing method according to any one of claims 30 to 33. 38. A packaged article produced according to the manufacturing method according to claim 34. 39. A packaged article produced according to the manufacturing method according to claim 35. 40. A packaged article produced according to the manufacturing method according to claim 36. 41. A packaging container produced using the film according to any one of claims 7 to 11. 42. A packaging container produced using the film according to claim 14. 43. A packaging container produced using the film according to claim 15. 44. A packaging container produced using the film according to claim 16. 45. A packaging container produced using the film according to claim 17. 46. A packaging container produced using the film according to claim 18. 47. A packaging container produced using the film according to claim 19. 48. A packaging container produced using a film produced according to the production method according to any one of claims 12, 13, or 20. 49, a multilayer polymeric film comprising a first extruded layer of ethylene vinyl alcohol copolymer and a second layer of vinylidene chloride copolymer coextruded with said first extruded layer of ethylene vinyl alcohol copolymer. 50, a multilayer polymeric film comprising a first extruded layer of ethylene vinyl alcohol copolymer, a second layer of vinylidene chloride copolymer, and a third layer of adhesive polymer, wherein said second layer and third layer are both coextruded with the first layer of ethylene vinyl alcohol copolymer, and the third layer of adhesive is bonded to both the first layer and the second layer with a peel strength of at least about 100 grams per inch width. The multilayer polymer film. 51. The multilayer polymer film of claim 48 or 49, wherein the vinylidene chloride copolymer is a vinylidene chloride methyl acrylate copolymer. 52. The multilayer polymer film of claim 48 or 49, wherein the vinylidene chloride copolymer is a vinylidene chloride vinyl chloride copolymer. 53, a multilayer polymer film comprising a first layer of ethylene vinyl alcohol copolymer and a second layer of vinylidene chloride copolymer, wherein the incremental oxygen permeability of the first layer of ethylene vinyl alcohol copolymer at 0% relative humidity is The multilayer polymer film has a corresponding incremental oxygen permeability of the vinylidene chloride copolymer second layer at 0% humidity. 54. The multilayer of claim 53, wherein the incremental oxygen permeability of the ethylene vinyl alcohol copolymer first layer at 50% relative humidity is less than the corresponding incremental oxygen permeability of the vinylidene chloride copolymer second layer at 50% relative humidity. polymer film. 55. The multilayer polymeric film of claim 53 or 54, wherein the vinylidene chloride copolymer is a vinylidene chloride methyl acrylate copolymer. 56. The multilayer polymeric film of claim 53 or 54, wherein the vinylidene chloride copolymer is a vinylidene chloride vinyl chloride copolymer. 57, a multilayer polymeric film comprising a first layer of ethylene vinyl alcohol copolymer, and second and third layers each comprising a vinylidene chloride copolymer and an adhesive polymer, wherein said second and third layers is coextruded with the first layer, and the third adhesive layer is interposed between the first and second layers and has a peel strength of at least 100 grams per inch width. a second layer, such that the incremental oxygen permeability of the first layer of the ethylene vinyl alcohol copolymer at 0% relative humidity is such that the incremental oxygen permeability of the first layer of the vinylidene chloride copolymer at 0% relative humidity is
Said multilayer polymeric film, wherein the incremental oxygen permeability of the layers is less. 58. The multilayer polymeric film of claim 57, wherein the incremental oxygen permeability of the ethylene vinyl alcohol copolymer first layer at 50% relative humidity is less than the incremental oxygen permeability of the vinylidene chloride copolymer second layer at 50% relative humidity. . 59. The multilayer polymer film of claim 57 or 58, wherein the vinylidene chloride copolymer is a vinylidene chloride vinyl chloride copolymer. 60. The multilayer polymeric film of claim 57 or 58, wherein the vinylidene chloride copolymer is a vinylidene chloride methyl acrylate copolymer. 61. Incremental water vapor permeability between the first layer of ethylene vinyl alcohol copolymer and the outer surface of the film through the layer of vinylidene chloride copolymer, and water vapor permeation between the first layer and the other surface of the film. 50. The multilayer polymeric film of claim 49, wherein the multilayer polymeric film has a ratio of about 0.25/1 or less. 62. Incremental water vapor permeability between the first layer of ethylene vinyl alcohol copolymer and the outer surface of the film through the layer of vinylidene chloride copolymer, and the water vapor permeation between the first layer and the other surface of the film. 51. The multilayer polymeric film of claim 50, wherein the ratio of 0.25 to 1. 63. Incremental water vapor permeability between the first layer of ethylene vinyl alcohol copolymer and the outer surface of the film through the layer of vinylidene chloride copolymer, and water vapor permeation between the first layer and the other surface of the film. 52. The multilayer polymeric film of claim 51, wherein the ratio of 0.25 to 1.5% is about 0.25/1 or less. 64. Incremental water vapor transmission between the first layer of ethylene vinyl alcohol copolymer and the outer surface of the film through the layer of vinylidene chloride copolymer, and water vapor transmission between the first layer and the other surface of the film. 53. The multilayer polymeric film of claim 52, wherein the ratio of 0.25 to 1. 65. Incremental water vapor permeability between the first layer of ethylene vinyl alcohol copolymer and the outer surface of the film through the layer of vinylidene chloride copolymer, and water vapor permeation between the first layer and the other surface of the film. 54. The multilayer polymeric film of claim 53, wherein the ratio of 0.25 to 1. 66. Incremental water vapor transmission between the first layer of ethylene vinyl alcohol copolymer and the outer surface of the film through the layer of vinylidene chloride copolymer, and water vapor transmission between the first layer and the other surface of the film. 55. The multilayer polymeric film of claim 54, wherein the ratio of polyester to polyester is about 0.25/1 or less. 67. Incremental water vapor permeability between the first layer of ethylene vinyl alcohol copolymer and the outer surface of the film through the layer of vinylidene chloride copolymer, and water vapor permeation between the first layer and the other surface of the film. 56. The multilayer polymeric film of claim 55, wherein the ratio of polyester to polyester is about 0.25/1 or less. 68. Incremental water vapor transmission between the first layer of ethylene vinyl alcohol copolymer and the outer surface of the film through the layer of vinylidene chloride copolymer, and water vapor transmission between the first layer and the other surface of the film. 57. The multilayer polymeric film of claim 56, wherein the ratio of 0.25 to 1 is less than or equal to about 0.25/1. 69. Incremental water vapor permeability between the first layer of ethylene vinyl alcohol copolymer and the outer surface of the film through the layer of vinylidene chloride copolymer, and water vapor permeation between the first layer and the other surface of the film. 58. The multilayer polymeric film of claim 57, wherein the ratio of polyester to polyester is about 0.25/1 or less. 70. Incremental water vapor permeability between the first layer of ethylene vinyl alcohol copolymer and the outer surface of the film through the layer of vinylidene chloride copolymer, and the water vapor permeation between the first layer and the other surface of the film. 59. The multilayer polymeric film of claim 58, wherein the multilayer polymeric film has a ratio of about 0.25/1 or less. 71. Incremental water vapor permeability between the first layer of ethylene vinyl alcohol copolymer and the outer surface of the film through the layer of vinylidene chloride copolymer, and water vapor permeation between the first layer and the other surface of the film. 60. The multilayer polymeric film of claim 59, wherein the multilayer polymeric film has a ratio of about 0.25/1 or less. 72. Incremental water vapor transmission between the ethylene vinyl alcohol copolymer first layer and the outer surface of the film through the vinylidene chloride copolymer layer and between the first layer and the other surface of the film. 61. The multilayer polymeric film of claim 60, wherein the ratio of polyester to polyester is about 0.25/1 or less. 73. A packaging container produced using the film according to claim 49. 74. A packaging container produced using the film according to claim 50. 75. A packaging container produced using the film according to claim 51. 76. A packaging container produced using the film according to claim 52. 77. A packaging container produced using the film according to claim 53. 78. A packaging container produced using the film according to claim 54. 79. A packaging container produced using the film according to claim 55. 80. A packaging container produced using the film according to claim 56. 81. A packaging container produced using the film according to claim 57. 82. A packaging container produced using the film according to claim 58. 83. A packaging container produced using the film according to claim 59. 84. A packaging container produced using the film according to claim 60. 85. A packaging container produced using the film according to claim 61. 86. A packaging container produced using the film according to claim 62. 87. A packaging container produced using the film according to claim 63. 88. A packaging container produced using the film according to claim 64. 89. A packaging container produced using the film according to claim 65. 90. A packaging container produced using the film according to claim 66. 91. A packaging container produced using the film according to claim 67. 92. A packaging container produced using the film according to claim 68. 93. A packaging container produced using the film according to claim 69. 94. A packaging container produced using the film according to claim 70. 95. A packaging container produced using the film according to claim 71. 96. A packaging container produced using the film according to claim 72. 97, (a) a first composition of ethylene vinyl alcohol copolymer and a second composition of vinylidene chloride copolymer;
and a respective first and second thickness for each first and second layer made from the first and second compositions.
selecting a thickness such that the incremental oxygen permeability of the first layer of ethylene vinyl alcohol copolymer at 0% relative humidity is lower than the incremental oxygen permeability of the second layer of vinylidene chloride copolymer at 0% relative humidity; and (b) producing a film made from the first composition and the second composition, the film having the first layer and the second layer having approximately the first thickness and the second thickness. A method for producing a film, including the steps of; 98. The method of making a film according to claim 97, wherein the step of making the film includes coextruding the first layer of ethylene vinyl alcohol copolymer and the second layer of vinylidene chloride copolymer. 99, from the group consisting of ethylene vinyl acetate copolymers containing 15% or more of vinyl acetate, blends and copolymers of polypropylene and ethylene vinyl acetate copolymers, ethylene methyl acrylate copolymers, anhydride-modified polypropylene, and anhydride-modified ethylene vinyl acetate copolymers selecting an extrudable composition as an adhesive; and coextruding said selected extrudable adhesive with said first layer and said second layer to interpose said extrudable composition between said first layer and said second layer. 99. The film manufacturing method according to claim 98, comprising the following steps: forming a third layer. 100, the ethylene vinyl alcohol copolymer first
The ratio of the incremental water vapor permeability between the layer and the outer surface of the film through the vinylidene chloride copolymer layer to the water vapor permeability between the first layer and the other surface of the film is 0.
．． 98. The film manufacturing method according to claim 97, comprising the step of configuring the film so that the ratio is 25/1 or less. 101, a film produced according to the production method according to claim 97. 102. A film produced according to the production method according to claim 98. 103, a film produced according to the production method according to claim 99. 104. A film produced according to the production method according to claim 100. 105, (a) a first layer of ethylene vinyl alcohol copolymer; (b) a second layer of vinylidene chloride copolymer; and (c) a heat sealable third layer, wherein said first layer of ethylene vinyl alcohol copolymer is the vinylidene chloride copolymer second layer and the heat sealable third layer.
interposed between a first layer of the ethylene vinyl alcohol copolymer;
the ratio of the incremental water vapor permeability between the layer and the outer surface of the film through the vinylidene chloride copolymer layer to the water vapor permeability between the first layer and the other surface of the film is about 0.25. /1 or less. 106. The multilayer polymer film of claim 105, wherein the heat sealable third layer composition is selected from the group consisting of polypropylene, low density polyethylene, medium density polyethylene, ethylene vinyl acetate copolymers, and ionomers. 107. A packaging container produced using the film according to claim 105, with the third layer of sealant disposed toward the inside of the packaging container. 108. A packaging container produced using the film according to claim 106, with the third layer of sealant disposed toward the inside of the packaging container. 109. A packaging container made using a packaging sheet material, wherein the packaging sheet material defines an enclosed space within the packaging container and is isolated from the surrounding environment outside the packaging container; The packaging sheet material includes a first layer of ethylene vinyl alcohol copolymer and a second layer of vinylidene chloride copolymer, and one of the enclosed spaces and the surrounding environment are in contact with the other of the enclosed spaces and the surrounding environment. has a lower humidity than the surrounding environment and constitutes a low humidity side, the other of said enclosed space and said surrounding environment constitute a high humidity side, and said ethylene vinyl alcohol copolymer and said surrounding environment constitute a high humidity side. The packaging container, wherein the barrier to moisture transmission between the low density side is substantially less than the barrier to moisture transmission between the ethylene vinyl alcohol copolymer and the high humidity side. 110, wherein the water vapor permeability ratio of (i) the ethylene vinyl alcohol copolymer and the high humidity side to (ii) the ethylene vinyl alcohol copolymer and the low humidity side is about 0.25/1 or less. Packaging container as described. 111, comprising a heat-sealable third layer disposed on the inner surface of the packaging sheet material, wherein the heat-sealable third layer is polypropylene, low density polyethylene, medium density polyethylene, ethylene vinyl acetate copolymer; Claim 109 selected from the group consisting of ionomers.
Packaging container as described. 112, comprising a heat-sealable third layer disposed on an inner surface of the packaging sheet material, wherein the heat-sealable third layer is polypropylene, low density polyethylene, medium density polyethylene, ethylene vinyl acetate copolymer; Claim 110 selected from the group consisting of ionomers.
Packaging container as described. 113. The packaging container according to any of claims 109 to 112, wherein the low humidity side includes the enclosed space. 114. Claim 1, wherein the low humidity side includes the surrounding environment.
The packaging container according to any one of 09 to 112. 115. The packaging container according to any one of claims 109 to 112, wherein the packaging sheet material comprises a coextrusion of the first and second layers. 116. The packaging container of claim 115, including adhesive means interconnecting said first and second layers with a peel strength of at least about 100 grams per inch width. 117. The packaging container of claim 115, wherein the vinylidene chloride copolymer second layer comprises vinylidene chloride methyl acrylate. 118. The packaging container of claim 115, wherein the incremental oxygen permeability of the ethylene vinyl alcohol copolymer first layer at 50% relative humidity is less than the incremental oxygen permeability of the vinylidene chloride copolymer second layer at 50% relative humidity. 119. A packaging container made using the film according to claim 1, wherein the packaging material comprising the film defines an enclosed space within the packaging container and absorbs the surrounding environment outside the packaging container. one of said enclosed spaces and said surrounding environment have a lower humidity than the other of said enclosed spaces and said surrounding environment to constitute a low humidity side; The other of the spaces and the surrounding environment constitute a high humidity side, and a barrier to moisture permeation between the ethylene vinyl alcohol copolymer and the low density side is formed between the ethylene vinyl alcohol copolymer and the high humidity side. said packaging container having substantially less than a barrier to moisture permeation during said packaging. 120, the composition of the third layer contains vinyl acetate from about 18 to
Claim 119 selected from the group consisting of 35% ethylene vinyl acetate copolymer, anhydride modified ethylene vinyl acetate copolymer, and anhydride modified polypropylene.
Packaging container as described. 121. The packaging container of claim 119 or 120, comprising a fourth layer of sealant in the film, wherein the second layer of vinylidene chloride copolymer is interposed between the third layer and the fourth layer of sealant. . 122. The packaging container of claim 121, wherein the composition of the sealant layer is selected from the group consisting of linear low density polyethylene, homopolymers and copolymers of polypropylene, and polyethylene having a resin density of at least 0.940. 123, comprising a fifth layer of adhesive between the second layer of vinylidene chloride copolymer and the fourth layer of sealant, wherein the composition of the fifth layer is ethylene vinyl acetate containing about 15% or more of vinyl acetate. Claim 121 selected from the group consisting of copolymers, blends and copolymers of polypropylene and ethylene vinyl acetate copolymers, ethylene methyl acrylate copolymers, anhydride modified polypropylene, and anhydride modified ethylene vinyl acetate copolymers.
Packaging container as described. 124. A packaging container made using the film of claim 7, 8 or 9, wherein the packaging material comprising the film defines an enclosed space within the packaging container. isolated from the surrounding environment outside the packaging container, one of the enclosed spaces and the surrounding environment having a lower humidity than the other of the enclosed spaces and the surrounding environment, forming a low humidity side; the other of said enclosed spaces and said surrounding environment constitute a high humidity side, wherein said barrier to moisture permeation between said ethylene vinyl alcohol copolymer and said low density side is formed by said ethylene vinyl alcohol copolymer. The packaging container has substantially less than a barrier to moisture transmission between the copolymer and the high humidity side. 125. Claim 119 or 120, wherein the third layer of adhesive is in surface contact with the first and second layers, thereby bonding the first and second layers to each other.
The packaging container described in . 126, wherein the film includes a fourth layer of sealant, wherein the second layer of vinylidene chloride copolymer is interposed between the third layer and the fourth layer of sealant.
25. The packaging container according to 25. 127, (a) making a packaging container using a multilayer packaging sheet material having a first layer comprising an ethylene vinyl alcohol copolymer and a second layer comprising a vinylidene chloride copolymer, the sheet material comprising: Said first
(b) an article for supplying moisture into the packaging container; (c) hermetically sealing said container; (d) processing said hermetically sealed container through a high moisture environment, wherein said sheet material is absorbing moisture from a high moisture environment, thereby reducing the instantaneous effective oxygen barrier properties of said ethylene vinyl alcohol copolymer; and (e) following step (d), said hermetically sealed container. returning the ethylene vinyl alcohol copolymer to a low moisture environment, wherein the sheet material releases the moisture between the ethylene vinyl alcohol copolymer and the low moisture environment, thus restoring the oxygen barrier of the ethylene vinyl alcohol copolymer; A method of packaging an article, including a process. 128. A packaged article made according to the method of claim 127.