JPS60242054A - Flexible gas barrier property laminated packaging material having excellent resistance to fatigue from flexing - 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 A1 Technical Field of the Invention The present invention relates to a flexible laminated packaging material whose gas barrier properties do not deteriorate even under extremely severe bending fatigue. Specifically, a thin film made of a saponified ethylene-vinyl acetate copolymer (hereinafter referred to as EVO I) having gas barrier properties such as oxygen and carbon dioxide gas is used as an intermediate layer, and a surface layer is provided on both sides of the intermediate layer. Each layer is provided via an adhesive resin consisting essentially of modified linear low-density polyethylene obtained by chemically bonding ethylenically unsaturated carboxylic acid or its anhydride to linear low-density polyethylene. As a result, the airtight packaging for items that are easily deteriorated using the packaging material can maintain excellent gas barrier properties even against the extremely severe bending fatigue that the packaging material receives during transportation and handling. The object of the present invention is to provide a laminated flexible packaging material that is effective in preventing deterioration of packaged items.

B. Prior Art The function of flexible laminated packaging materials is basically the preservation of the packaged items, that is, the prevention of deterioration, and for this reason, the packaging materials are particularly required to have transport vibration strength and bending fatigue resistance. In particular, when used as the inner container of a so-called bag-in-box - a container that combines a foldable thin-walled plastic inner container with an outer cardboard box that is stackable, portable, and suitable for printing, a high degree of this property is required. required.

The packaging material is used by laminating various plastic films to take advantage of the characteristics of each material, but the most common combination is, for example, a base film to maintain mechanical strength and a heat-sealable material. The material is selected according to the requirements of the packaged item. In particular, for applications where the oxygen and other gas barrier properties of the base film are unsatisfactory, a barrier layer with even higher gas barrier properties is provided on the base layer.
A method is adopted in which thermopolymer resin is laminated so that this barrier layer is used as an intermediate layer and at least one outer layer is made of a heat-sealable material. For example, the conventional bag in pock,
The heat-sealable parts of the bag-in-box's inner container are always known, so it is mainly made of heat-sealable polyethylene, especially soft polyethylene. Therefore, physical strength, mJ, as mentioned above, transport vibration strength, and bending fatigue resistance are particularly important. Resin is more preferably used. Furthermore, when gas barrier properties such as oxygen are required as performance requirements become more sophisticated, the inner container may be constructed using a combination of nylon film, Saran-coated nylon film, aluminum-deposited nylon film, aluminum-evaporated polyester film/REM, etc. is beginning to be put into practical use. K to provide good gas barrier properties
For example, saponified ethylene-vinyl acetate copolymer, polyvinylidene chloride, aluminum foil, vapor-deposited film of metal, etc. are used. However, although these have excellent gas barrier properties, their mechanical strength is generally low, and in particular they cannot withstand bending fatigue. Therefore, it is used by being laminated between a base material layer with excellent mechanical strength and a heat-sealable material. 1. Barrier properties may deteriorate due to holes or pinholes that may occur in the barrier layer used as an intermediate layer even when no pinholes are formed in the constituent material. No material has been found that is unable to maintain excellent gas barrier properties against extremely severe bending fatigue and is practically satisfactory.

The behavior of laminated packaging materials whose barrier layer is a layer mainly composed of polyvinylidene chloride resin, aluminum foil, a vapor-deposited resin layer of metal, etc. is shown in, for example, Japanese Patent Laid-Open No. 7477/1983. That is, actually using the packaging material,
The reason why the gas barrier property after transportation and handling of the packaged package is not always satisfactory, and the practical shelf life after the primary distribution, which is the most important, is often betrayed is because of the barrier layer located in the middle layer. Due to damage. EV (M resin) is the most excellent material for the intermediate layer provided to improve gas barrier properties, and is preferably used as a barrier material for various multilayer films and containers with multilayer structures.

This resin not only has excellent barrier properties, but also has excellent transparency, oil resistance, printability, moldability, etc., and has extremely advantageous properties such as not impairing the properties of the base resin. This is because it has

However, in fields where bending fatigue resistance is particularly required, there have been no examples of EVOH resin being satisfactorily used as a barrier in laminated packaging materials. In particular, as mentioned above, EVO is used in the bag-in-box inner container, which has gas permeability such as oxygen, which is strongly recommended to withstand bending fatigue due to transportation vibration.
A flexible laminated packaging material that uses H resin and satisfies these requirements has not been found, and has excellent barrier properties with one barrier layer and bending fatigue strength that can withstand transportation vibration. The development of was one of the important issues.

C0 Objectives, structure, and effects of the present invention The inventors have E
Although VOI (film) has the above-mentioned excellent properties, it not only has the major drawback of being significantly inferior in bending fatigue resistance compared to thermoplastic films such as polyethylene, polypropylene, nylon, and thermoplastic polyester. In multi-layer flexible packaging materials that are laminated with resin layers that are resistant to bending, and that use an EVOH resin layer as an intermediate layer, unexpectedly it seems to be related to physical properties such as the stiffness of EVOH, but the bending resistance of the packaging material It is even more surprising that the fatigue resistance is significantly lower than the bending fatigue resistance exhibited by the thermoplastic Vt resin that is strong against bending fatigue, and that the bending fatigue is caused to occur in the laminated packaging material with less bending fatigue. Until the occurrence of the pinhole, the E VOI (
This seems to be due to the fact that nicks, pinholes, etc. due to bending fatigue do not occur in the EVO layer even after the bending fatigue that the layer alone can withstand is exceeded, but there is almost no decrease in barrier properties. We found that the behavior was significantly different from that of conventional laminated packaging materials that used vinylidene chloride resin as a barrier layer and as an intermediate layer, and from this point of view, we developed EVO.
The present invention has been completed through extensive research into a flexible gas-barrier laminated packaging material with excellent bending fatigue resistance that uses the H layer as a barrier layer.

That is, the present invention provides a flexible laminated packaging material in which a thin film of EVULI is used as an intermediate layer, surface layers are provided on both sides of the intermediate layer, and each layer is disposed via an adhesive resin, in which the adhesive resin is substantially Fugisipuru is a linear low-density polyethylene that is obtained by chemically bonding ethylenically unsaturated carboxylic acid or its anhydride to linear low-density polyethylene, and has excellent resistance to ArJ bending fatigue. It is an object of the present invention to provide a gas-barrier laminated packaging material.

The bending fatigue resistance is determined based on data such as the dependence of the gas barrier reduction on the number of bends and the number of bends until the formation of pinholes in an evaluation test conducted using a so-called gelpo flex tester. It is possible to judge the superiority or inferiority of the bending fatigue resistance of laminated packaging materials made of The present inventors used a Gelpoflex tester to test single films of thermoplastic resins and laminate films with multilayer structures made of various resins, particularly films with different adhesive resins used between each layer of the laminate film. , the relationship between the number of bends and the number of pinholes, the number of bends that lead to the formation of pinholes, and the relationship between the number of bends and barrier properties (for example, oxygen permeation rate) in the process leading to the formation of pinholes for multilayer laminates. As a result of measuring a wide range of relationships, we discovered several facts.

In other words, (1) all EVOH resin films have extremely poor bending fatigue resistance, and are far below the transport vibration strength level that can withstand practical use, and (2) the high-pressure method low density that has been commonly used in the past Films made of various resins such as polyethylene, low-pressure high-density polyethylene, nylon, polypropylene, and thermoplastic polyester have significantly superior bending fatigue resistance compared to the EVO) I resin film, but Although the details of the flexural fatigue resistance of the laminate film laminated as an intermediate layer are not clear, there is a significant decrease that appears to be due to the presence of the EVOH layer, that is, compared to the excellent flexural fatigue resistance of the single resin film. (3) More surprisingly, there was almost no decrease in gas barrier properties until pinholes were observed in the laminate with the EVOI=I layer as an intermediate layer. , (4) In particular, the EVOH layer is provided as an intermediate layer and both surface layers are provided via an adhesive resin, but the laminate is laminated using a specific modified linear low-quality polyethylene as the resin, It was observed that the bending fatigue resistance was significantly improved. The details of this phenomenon are not yet clear, but
The effect of this improvement is the carbon number of α-olefin, which is a copolymerization component of the linear low-density polyethylene before paternity, the heat of fusion, Young's modulus, and Young's modulus determined by thermal analysis using a differential scanning calorimeter. is deeply involved in the paternal component of
This is particularly noticeable when these are present in a selected specific region and a modified polyethylene modified with a specific paternal component is used as the adhesive resin.

01 Detailed Description of the Invention The linear low-density polyethylene used in the present invention is a linear low-density polyethylene having substantially no long chain branches. In general, a quantitative measure of the number of long chain branches 0-4η)b
/[η]l([η)b is the limiting viscosity of branched polyethylene,
[η]e is the intrinsic viscosity of linear polyethylene with the same molecular weight as branched polyethylene) is approximately 1 (generally 0.
(often in the range of 9 to 1) and has a density of 0.910 to 0.945. (The O value of conventional high-pressure low-density polyethylene is o, i~0.
It is 6. ) The method for producing linear low density polyethylene is not particularly limited. Examples of typical manufacturing methods are 7 to 45.
Kg/am' pressure (usually 2000-3oooKq/cm' for high pressure low density polyethylene), 75
α-olefin having 3 or more carbon atoms, preferably 4 or more carbon atoms, and more preferably 5 to 10 carbon atoms, using a chromium-based catalyst or a Ziegler catalyst at a temperature of ~100°C (120 to 250°C in the case of high-pressure low density polyethylene) , such as propylene, phthene-1, methylpentene-1, hexene-1
There is a method of copolymerizing ethylene by copolymerizing α-olefins such as , octene-1, etc. As the polymerization method, a solution washing liquid phase method, a slurry washing liquid phase method, a fluidized bed vapor phase method, an agitation vapor phase method, etc. are used.

When the linear low density polyethylene is further modified with an ethylenically unsaturated carboxylic acid or its anhydride, the linear low density polyethylene is modified with the carboxylic acid or its anhydride in the presence of a radical initiator, for example. Methods known per se can be employed, such as grafting.

Ethylenically unsaturated carboxylic acids or their anhydrides used in the present invention include monobasic unsaturated fatty acids such as acrylic acid and methacrylic acid, or dibasic unsaturated fatty acids such as maleic acid, fumaric acid, and itaconic acid. , and anhydride of dibasic unsaturated fatty acid, maleic anhydride,
Such as itaconic anhydride.

In particular, both surface layers and intermediate to EVO) of the laminated packaging material
From the viewpoint of adhesion to the J layer, dibasic unsaturated fatty acid anhydrides are preferred, maleic anhydride and itaconic anhydride are more preferred, and maleic anhydride is most preferred.

To obtain the modified linear low-degree polyethylene chemically bonded with ethylenically unsaturated fatty acids or their anhydrides used in the present invention, various methods known per se can be employed. One of them is a solution grafting process in which a grafting monomer, an ethylenically unsaturated fatty acid or its anhydride, and a catalyst, such as a radical initiator such as a peroxide, are added to the polyethylene dissolved or suspended in a suitable solvent. (e.g., JP-A-50-4144, JP-A-50-4189, etc.), and other methods in which, for example, powdered polyethylene and ethylenically unsaturated fat as a graft monomer are used in the absence of a liquid medium. A melt graft polymerization method (e.g., special Publication No. 50-74493, etc.).

The chemical bond amount of ethylenically unsaturated fatty acid or its anhydride to linear low density polyethylene is 0.01 to 15
Weight %, more preferably 0.05 to 10 weight %, still more preferably 0.1 to 5 weight % is suitable. If the amount of bonding is less than 0.01% by weight, the adhesiveness will be poor and the desired effect will not be obtained. If the amount exceeds 15% by weight, the resin may be colored or gelatinized, leading to the generation of foreign matter, which is not preferable. Examples of graft polymerization M include common peroxide catalysts such as dicumyl peroxide, di-1-butyl peroxide, t-butyl peroxybenzoate, and benzoyl peroxide, and azo compounds such as azobisisobutyronitrile. In graft polymerization, there are cases where it is sufficient to simply apply heat without using a graft polymerization catalyst such as peroxide, but this is not preferable because only a product with a high gel fraction can be obtained.

As mentioned above, the effect of the present invention is deeply related to the number of carbon atoms in the α-olefin, the heat of fusion of the linear low-density polyethylene determined by thermal analysis using a differential scanning calorimeter, and Young's modulus. However, to be more specific, it is as follows. Linear low density polyethylene is preferably used in the present invention, but the heat of fusion is 25 Cal! / f or less, preferably 25-5 Qal/f, or Young's modulus at 20°C is 22 Kq/- or less, preferably 22-5
The effect of the present invention is most remarkable for the polyethylene having a ratio of 3 to 9/14, more preferably 22 to 5 to 9/-, particularly when both are in the above range.

The heat of fusion and Young's modulus in the above range vary somewhat depending on the polymerization method and polymerization conditions, but generally speaking, the content of the α-olefin, which is a copolymer component, is about 2 mol% or more, preferably about 2 mol%. It is often obtained in the range of ~7 mol%. For linear low density polyethylene whose copolymerization component is butene-1, the heat of fusion is 15 cat/9 or less,
Alternatively, the effect of the present invention is more remarkable when the Young's modulus at 20° C. is 12 Kq/− or less, and especially when both of them are in the above range, the effect can be most significantly enjoyed.

The low density polyethylene whose heat of fusion and Young's modulus are in the above range generally has a butene-1 content of about 4 mol%.
It is often obtained in the above areas.

If the content is too large, other physical properties of the polyethylene become unsatisfactory, which is not preferable, and the content is desirably at most several mol%, for example 77 mol%. Furthermore, as described above, the effects of the present invention can be enjoyed with linear low-density polyethylene whose heat of fusion and/or Young's modulus are in the specific range, but particularly with α-olefins having 5 or more carbon atoms, for example, 5 to 10 carbon atoms. The effect of w4 can be greatly enjoyed by the polyethylene containing as a copolymerization component. In this case, for the same reasons as mentioned above, the content of the 6-olefin is preferably 2 to 7 mol/L/%, more specifically 2 to 6 mol%, and the heat of fusion is - It is related to the olefin content, etc., but in particular, the heat of fusion is 25 to 5 CBl! /f, and the Young's modulus is 22KQ/- or less, preferably 2
2-3 Kq/mtA, more preferably 22-5 Kg
/ld. Among these olefins, the effect of the present invention is more remarkable, and 4-methy)v is easily obtained industrially.
Linear low density polyethylene containing -1-pentene as a copolymerization component is one of the most preferred. In the case of conventional high-pressure low-density polyethylene, the effects of the present invention cannot be enjoyed even if the heat of fusion and/or Young's modulus as determined by thermal analysis using a differential scanning calorimeter are in the above range.

The laminated packaging material of the present invention must not cause delamination during the bending fatigue test using the Gelpoflex tester, but the adhesive resin of the present invention has adhesive Kl
E Won layer, polyethylene, polypropylene,
The interlayer adhesion between the layer and the layer of polyamide such as nylon-6 or thermoplastic 7g4 resin such as ethylene-vinyl acetate copolymer can withstand severe bending fatigue without causing any delamination.

The thickness of the adhesive resin layer is related to the bending fatigue resistance of the laminated packaging material of the present invention, and generally speaking, as the layer thickness increases, the bending fatigue resistance decreases. In order to bring out the effects of the present invention more markedly, it is preferably 5μ or less, i o I
t or less is more preferable. Furthermore, if the adhesive resin layer is too thin, it will be technically difficult to provide the layer with a uniform thickness without any breaks, so in practical terms, the layer thickness should be 】μ or more, more preferably 2μ or more. suitable.

Furthermore, the fact that the adhesive resin is substantially the modified linear low-density polyethylene means that the present invention also includes embodiments in which the modified linear low-density polyethylene is blended with unmodified or linear low-density polyethylene. includes, and the modified polyethylene contains 0.01 ethylenically unsaturated carboxylic acid or its anhydride.
~15% by weight of the polyethylene chemically bonded;
Moreover, the content of the carboxylic acid or its anhydride component in the blend is 0.01% by weight or more and less than 15% by weight, preferably 0.05 to 10% by weight, more preferably 7o,
This means that the effects of the present invention can be enjoyed if the ratio is x to 5%. In this case, the linear low-density polyethylene blended with the linear low-density polyethylene before modification of the modified polyethylene may be the same or different, and the latter may contain two or more different types of linear low-density polyethylene. It may also be a mixture of linear low density polyethylenes.

The modified linear low-density polyethylene of the present invention is a mixture of two or more modified linear low-density polyethylenes that differ insofar as the content of the modifying component is selected to be within the above range. Even in this case, the effects of the present invention can be enjoyed.

The EVOH resin used in the present invention has an ethylene content of 25
~60 mol % and a saponification degree of 95% or more are preferably used. When the ethylene content is 25 mol% or less, not only the moldability decreases but also the stiffness of the EV014 increases, but the effect of the present invention is diminished, and when the ethylene content is 60 mol% If it exceeds this value, although the rigidity decreases, the gas barrier property against oxygen and the like, which is the most characteristic feature of the resin, decreases and becomes unsatisfactory. The EVOLT resin has an ethylene content in the range of 25 to 60 mol%, and even if it is a blend of two or more resins with different ethylene contents, it is within the range that shows compatibility. It is possible to enjoy the effects of the invention. The degree of saponification of the resin is preferably 95% or more.

If it is less than 95%, the barrier properties will deteriorate, which is not preferable. Furthermore, EVO treated with boron compounds such as boric acid
Modified EVOH obtained by copolymerizing a third component such as H, a silicon-containing olefinic unsaturated monomer with ethylene and vinyl acetate, and saponifying it can also be melt molded and has a degree of modification within a range that does not impair Bayer property. If so, the effects of the present invention can be enjoyed.

As mentioned above (EVOI (in the case of 9 layers, the bending fatigue resistance is.

Although it shows a slight improvement trend as the thickness decreases, this is a phenomenon in the area where the bending fatigue resistance is far below the level required to meet the practically required transport vibration strength. It's nothing more than that. However, in the structure of the laminated packaging material of the present invention, the number of times the gellevoflex tester is bent is
A peculiarity is recognized in that the layer thickness dependence of EVOH present as an intermediate layer is extremely pronounced. If the thickness of the EVOH layer exceeds 20 μm, the bending fatigue resistance decreases and the effects of the present invention are diminished, which is not preferable. In order to fully enjoy the effects of the present invention, the thickness of the Evou layer is preferably 20 μm or less, more preferably 15 μm or less. From the viewpoint of bending fatigue resistance alone, a thickness of 10 μm or less is most suitable. However, when there are higher requirements regarding gas barrier properties such as oxygen, it often happens that the thickness of the intermediate layer of 20/I or less cannot satisfy the requirements. The most preferred embodiment of the present invention, which satisfies higher requirements regarding bending fatigue resistance and barrier properties, is to select the thickness of the J5VOH layer to be 20μ or less, preferably 15μ or less, more preferably 10μ or less. The structure is such that two or more EVOH layers are provided depending on the degree of high barrier properties required. From the viewpoint of bending fatigue resistance, EV
Although it is preferable that the thickness of the OH layer be as small as possible, the difficulty in terms of molding technology increases accordingly. Practically speaking, a value of 2μ or more is preferable, and a value of 5μ or more is relatively less difficult from this point of view and is therefore more suitable. If it is less than 2μ, pinholes often occur in the EVOH layer and the yield of non-defective products decreases. When providing a plurality of such barrier layers, EVOH with the same ethylene content may be used for all of the layers, and if the relative humidity inside the container is greater than the relative humidity outside the container, e.g. When the packaged item is an aqueous mixture such as wine, etc., the positional relationship of each layer of the plurality of barrier layers is such that EVOH [with a lower ethylene content] is placed on the outside in relation to the humidity dependence of the barrier properties of EVOH. , it is preferable to arrange the upper VOR layer with a higher ethylene content on the inside, and when the relative humidity relationship is reversed, it is preferable to arrange the EVOH layer in the opposite positional relationship, etc. The optimal configuration can be selected according to each purpose. In this case, in order to obtain the effect of adopting this structure, it is preferable that at least 2M of the barrier layer be composed of EVOI:1 having a different W content of 5 mol % or more.

The laminated packaging material according to the present invention is intended to be heat-sealed and used as various flexible packaging materials, such as when used as a component of the inner container of a bag-in-box, and at least one of the surface layers Although the surface layer needs to be a heat-sealable thermostatic resin, it may be another resin layer that cannot be heat-sealed. The resin constituting the surface layer includes high-pressure low-density polyethylene, low-pressure high-density polyethylene, linear low-density polyethylene,
Examples include polypropylene, polyamide resins such as nylon, polyester resins, and ethylene-vinyl acetate copolymer resins.

Among the resins constituting the surface layer, linear low-density polyethylene and ethylene-vinyl acetate copolymer are more preferably used. When linear low-density polyethylene is used in at least one of the surface layers, especially when it is used in both surface layers, the bending fatigue resistance of the constituent material is significantly improved. In particular, although the details are not clear, the improvement effects include the number of carbon atoms in the α-olefin, which is a copolymer component of the low-density polyethylene used in the surface layer, and the heat of fusion based on thermal analysis using a differential scanning calorimeter. , Young's modulus at 20° C., etc., and these are even more noticeable when the above-mentioned linear low-density polyethylene in a selected specific region is employed.

Another more suitable resin constituting the surface layer is ethylene-vinyl acetate copolymer. In particular, the copolymer having a vinyl acetate content of at least 7% by weight can enjoy the effects of the present invention more markedly. If the content is too large, the resin surface will become sticky, which is undesirable, and the content is preferably 12% or less. When the filling in a packaging container made of the laminated packaging material of the present invention is an aqueous mixture or a water-containing food, the copolymer is added to the outer surface layer in relation to the moisture permeation rate of both the inner and outer surface layers. The embodiment in which linear low-density polyethylene is used for the inner surface layer is one of the preferable configurations of the laminated packaging material. Furthermore, in the case of the packaging filling, when even better bending fatigue resistance is required, the copolymer having a higher moisture permeability than the polyethylene is added to both the inner and outer surface layers within the limit that satisfies the barrier properties. The thickness of the inner surface layer and the outer surface layer are selected so as to satisfy the above-mentioned conditions regarding the moisture permeation rate, and the constant moisture of the nvou is maintained in a suitable range. can. Although the pinhole resistance of the EVOfi single film was extremely poor, at the time when the pinhole resistance of the laminated film having the structure of the present invention was significantly improved,
Judging from the characteristics of the single film, it is natural that cracks or pinholes will occur in the intermediate EVOH layer, and the barrier properties of the laminated packaging material will deteriorate. Unlike conventional laminated packaging materials using barrier materials such as vinylidene chloride, the present invention is extremely unique in that no deterioration in barrier properties is observed.

In the laminated packaging material of the present invention, if each layer of the surface layer is too thin, for example, 10μ or less, other physical properties such as strength will deteriorate, so the thickness should not be less than 101t. Preferably, it is more preferably 20μ or more. If the thickness increases too much, the effect of the present invention will be diminished, so it is more preferable that each layer of the surface layer has a thickness of 60 μm or less. In particular, for the constituent material of the inner container of a bag-in-box, it can be suitably selected from a thickness range of 25 to 60 μm depending on the inner volume.

The laminated packaging material according to the present invention can be obtained by a known method such as a coextrusion method or an extrusion lamination method, and the present invention does not limit the lamination method. In addition, for example, the inner container of a bag-in-box using the laminated packaging material can be produced using a film sealing method in which a film with the laminated structure is obtained by a known method, then heat-sealed and a mouth part is attached. A multilayer parison made of the combination of the materials of the present invention is formed by a vacuum forming method in which the cap is physically fixed after forming the sheet with the thickness M configuration obtained by film formation, or a multilayer melt extrusion molding method. It can be obtained by a known method such as a blow molding method in which the body is held in a mold and molded with compressed air, and the body and the cap are thermally bonded using the heat of the parison and the air pressure.

The present invention will be further explained below with reference to Examples, but the present invention is not limited thereto.

//' 1 /' , / 12/' ノ/ / / Example 1 E with 61 mol% ethylene content and 99.4% 7Jj
An intermediate layer made of VOH resin with a thickness of 12μ, and 4-methyl-1-pentene with a thickness of 55μ on each side of the intermediate layer as a copolymerization component, containing 5.2% by mole of the copolymerization component, 190
℃, under a load of 2160 g, the surface layer is made of linear low density polyethylene (LLDPE) with a heat of fusion of 19 CaVg, and the interlayer
The above LL with a thickness of 5μ and a degree of maleic anhydride modification (chemical bonding weight of maleic anhydride to LLDPH) of 07%
After extruding three laminated films arranged through adhesive resin layers made of a modified product of IJPE, coextrusion method Iζ was carried out using a multilayer die head for three types and five layers. A bending fatigue test was performed on the laminated film until the occurrence of pinholes was observed, and the amount of oxygen gas permeation was measured at each stage up to the occurrence of the pinholes.

For the bending fatigue test, a 12in x 8irl) sample piece was made into a cylindrical shape with a diameter of 3yln using a Gerbo Flexo tester (manufactured by iM Gakko f1m), gripped at both ends, and the initial gripping interval was 7in, and the gripping interval at maximum bending was 11n. , the first 5-2-1n of the stroke is a twist of 44,000 degrees, and the subsequent 22+n are linear horizontal motions. Repeated reciprocating motion at a speed of 40 times/min at 20°C relative humidity 65
% conditions.

The amount of oxygen gas permeation can be measured using Modern Control
OX-TI manufactured by 1 company (AN 100 wo ([use, 2
0°C m vs. 1i (denoted as R11) 65% and 20°G8
Measured at 0% IIH. The samples after each stage of the bending fatigue test were made into a 12 inch x 8 inch plane, and measurements were taken at the center of the plane. Also, Young's modulus is A13TM D-882
-67, measured at 20℃ and relative humidity 65%.

The measurement results are shown in Table 1. During the bending fatigue test process leading up to the occurrence of vinyl poles, there was almost no ashing of oxygen permeation. In addition, the occurrence of pinholes was not observed until 5050 cycles of the bending fatigue test had passed, and when the plastic nail was inspected for presence or absence of plastic nails, one pinhole had already occurred. Moreover, delamination between each layer was not improved at all. In addition, the L
A film of LDPH was obtained separately and its Young's modulus was measured at 20°C.The results are as follows.

Table 1 Example 2 P with ethylene content of 45 mol% and saponification degree of 99.2%:
(2) The same procedure as in Example 1 was carried out except that OH resin was used as the intermediate layer, and the thickness of the surface layers (LLDPE) disposed on both sides of the intermediate layer was 40 μm on one side and 30 μm on the other side. No pinholes were observed after 5 cycles of the bending fatigue test, and two pinholes were observed after 5,600 cycles. 111i of oxygen permeation! The I grass values are shown in Table 2. No delamination between layers was observed.

Example 3 A laminated film having the following configurations: D/Ad/E/Ad/F/I, d/G was obtained using coextrusion equipment having a multilayer die head for 5 types and 7 layers. Each layer consists of each resin and layer thickness shown below.

Ad: Adhesive resin layer with a thickness of 5 μm made of modified LLDE with a maleic anhydride modification degree of 2.8% by weight of the LLDPE used in Example 1 DlG: 41 mol% of 4-methyl-1-pentene was heated at 15 caII/ g□) Thickness: 58 μm, I, i)
P E layer E, F: EVO with ethylene content of 58 mol%, saponification degree of 99.4%, thickness of 6 μm) 1 unit A bending fatigue test was conducted in accordance with Example 1. The bending fatigue rest 600
No pinholes were observed even after 0 and no return passes. The measured values of oxygen permeation at each stage up to the 6000 round trip are shown in Table 3. No delamination was observed between each layer.
'Shinaka・tsut:. The LLDPE film was separately obtained and measured at 20° C., and its Young's modulus was 7.5.

Example 4 E is an 8μ thick layer made of the same EVOH resin as in Example 1, and F is a 6μ thick layer made of the same EVOEI resin as in Example 2.
layer, LLDP using adhesive resin layer Ad for D and G
Modified LLDP with maleic anhydride modification degree of E of 5.1% by weight
The same procedure as in Example 6 was carried out except that the E layer was used. Even after 000 cycles of the bending fatigue test, no pinholes were observed. Table 4 shows the measured values of the amount of oxygen permeation at each stage up to the 6,000-year recovery. Note that no delamination between layers was observed.

Table 4 Example 5 In Example 1, a film was prepared in which the adhesive resin layer contained 1-heptene as a copolymer component, the content was 2.9 mol%, and the heat of fusion as measured by a differential scanning calorimeter was 21 cdl/g. LLDPH with a Young's modulus of 154-, which was obtained separately and measured at 20°C.
Modified LLDPE with maleic anhydride modification degree of 2.6% by weight
The same procedure as in Example 1 was carried out except that . Even after 5,500 cycles of the bending fatigue test, the occurrence of pinholes did not subside, and the value of oxygen permeation remained almost unchanged.
, 4 cc/7i, 24hr (20°C180%EH
) and f:,.

Example 6 In Example 1, butene-1 was used as one of the synthetic components, and a film with a content of the component of 51 mol % and a heat of fusion of 12 Ca (1/g) as measured by a differential scanning type thermometer was separately obtained. The same procedure as in Example 1 was carried out except that the adhesive resin layer was composed of modified LLDPE having a Young's modulus of 8-8 and a maleic anhydride susceptibility of 1.8% by weight as measured at 20°C. Fatigue test) After 5,000 round trips, no pinholes were observed, and there was almost no change in the oxygen permeation value.
It was 1.5 CCβ, 24 hr (20°C, 80% Bfi).

Example 7 Ethylene content! E with 11 mol% and saponification degree of 99.3%
An intermediate layer made of VOK resin with a thickness of 12μ, one of the surface layers located on both sides of the intermediate layer used in Example 1 with a thickness of 65μ, a surface layer made of LDPE, and the other side of the surface layer. The modified L used in Example 3 was prepared from an ethylene-vinyl acetate copolymer containing mBNN% vinyl acetate, with a surface layer of 35μ thick and 6μ between each layer.
A laminated film disposed through an adhesive resin layer consisting of E was subjected to a coextrusion method tζ using four extruders and a multilayer head for four types and five layers, and subjected to a bending fatigue test. The results are shown in Table 5. During the bending fatigue test process Cζ up to the occurrence of pinholes, there was almost no change in the m-cumulative permeation amount. However, the occurrence of small holes was not observed after 4,500 cycles of the bending fatigue test, and after 4,600 cycles, an inspection was conducted to check for the occurrence of small holes, and one pinhole had already occurred. I admitted that I was under pressure. Furthermore, no delamination between the layers was observed.

Example 8 In Example 7, the EV+JH layer was made of EVOkI resin with an ethylene content of 46 mol% and a saponification degree of 99.6%, and had a thickness of 14μ, and one of the surface layers was made of an ethylene-vinyl acetate copolymer. Vinyl acetate content or 9 layers
A 40μ thick layer consisting of 1% of the copolymer was prepared in the same manner as in Example 7, except that LLDPH used in Example 1 was modified with maleic anhydride and 2.5% by weight of modified LLDPE was used as the adhesive resin. I went. No pinholes were observed until after 5000 cycles of the bending fatigue test, and the result was 55 DO.
After the round trip, one bin keel was observed to have occurred.

Oxygen permeation was measured at each stage after 5,000 round trips, and all were measured at 20°C, 65% Bki and 80% El (
2 respectively under the conditions of. QCC/d, 24hr, 5.
Almost no change was observed with 5cCβ for 24 hours.

No delamination between the layers was observed at all.

Example 9 In Example 1, the adhesive resin contained 3.5 mol% of octene-1 as a copolymerization component, and the heat of fusion based on a differential scanning calorimeter was 17. The maleic anhydride modification degree of LLDPE with 17 g of Ca was 5. Example 1 was repeated except that .2% by weight of modified LLDPE was used.

No pinholes were observed even after 5000 reciprocations of the bending fatigue test.

The amount of oxygen permeation was measured at each stage up to 5,000 round trips, and the result was 0.7 ct2/74 at 20°C and 65% flu.
．． 241] r, 20℃, 80% B m Te 1.5 c
There was almost no change at each stage up to 5,000 round trips at c/i, 24 hours. In addition? No delamination between the 8 layers was observed.

Example 10 A multi-layered product consisting of two 12 μm thick layers of nvou resin with an ethylene content of 68 mol% and an I'ination degree of 99.4%, arranged with the following adhesive L7 interposed between them. An intermediate layer and a copolymerized butene-1 having a thickness of 35μ on both sides of the intermediate layer,
L with a component content of 5.1 mol%, a heat of fusion of 12 cdl/g based on thermal analysis with a differential scanning calorimeter, and a Young's modulus of 8 kg7- when a film was separately obtained and measured at 20°C.
A laminated film was obtained in which a surface layer consisting of L DrE was provided via a 5 μm adhesive resin layer of the modified LLDPE used in Example 5, and this was subjected to the bending fatigue test. Even after 4,500 cycles of the bending fatigue test, no pinholes were observed, and the oxygen permeation value was almost the same.1.5cc, 4', 24hr (20℃, 80%
BH).

Patent applicant Clara Co., Ltd. Representative Patent Attorney Ken Honda

Claims (1)

[Scope of Claims] (1) A thin film of saponified ethylene-vinyl acetate copolymer is used as an intermediate layer, and surface layers are provided on both sides of the intermediate layer, and each surface layer is disposed with an adhesive resin layer in between. In the flexible laminated packaging material, the adhesive resin is obtained by chemically bonding ethylenically unsaturated carboxylic acid or anhydride thereof to linear low-density polyethylene in an amount of o, ol-L1s by weight. A flexible gas-barrier laminated packaging material with excellent bending fatigue resistance, characterized by being made of modified linear low-density polyethylene. (2) Linear low-density polyethylene has an order prime number of 4 or more α-
The laminated packaging material according to claim 1, which contains an olefin as a copolymerization component. (3) The laminated packaging material according to claim 1 or 2, which has a heat of fusion of 25 ca//g or less based on thermal analysis of linear image and density polyethylene using a differential scanning calorimeter. (4) Linear low-density polyethylene has butene-1 as a copolymer component, and the heat of fusion as determined by thermal analysis using a differential scanning calorimeter is 1.
The laminated packaging material according to claim 1, which has a scat/fl or less. The laminated packaging material according to any one of claims 1 to 3, wherein the linear low-density polyethylene has a Young's modulus of 22 kg/- or less at 20°C. (6) The laminated packaging material according to claim 1 or 4, wherein the linear low-stiffness polyethylene contains butene-1 as a copolymerization component and has a Young's modulus of 12 KQ/a- or less at 20°C. t71 linear low density polyethylene has a wide prime number of 5 or more α-
The laminated packaging material according to claim 1, 3, or 5, which contains an olefin as a copolymer component. f8Jiftjl low-density polyethylene is 4-methyl-1
- The laminated packaging material according to claim 1, claim 35, or claim 5, which contains pentene as a copolymerization component.ヰ(91 adhesive resin is a linear low density polyethylene with 0.05 to 1% of ethylenically unsaturated carboxylic acid or its anhydride.
The laminated packaging material according to any one of claims 1 to 8, which is a modified linear low-density polyethylene obtained by chemically bonding 0% by weight. OD The laminated packaging material according to any one of claims 1 to 9, wherein the ethylenically unsaturated carboxylic acid or its anhydride is maleic anhydride. OD The saponified ethylene-vinyl acetate copolymer is The laminated packaging material according to any one of claims 1 to 10, which has an ethylene content of 25 to 6 O-1 = /L'% and a saponification degree of 95% or more. The laminated packaging material according to any one of claims 1 to 11, which is as follows: Claim 1, wherein the intermediate layer is made of at least two saponified ethylene-vinyl acetate copolymers. Laminated packaging material according to any one of Items 1 to 12. 04 A patent in which the intermediate layer made of a saponified ethylene-vinyl acetate copolymer includes at least two layers made of the saponified material having ethylene contents different by 5 mol% or more. A laminated packaging material according to any one of claims 1 to 13. A patent in which the intermediate layer made of a saponified ethylene-vinyl acetate copolymer has at least two layers, each layer having a thickness of 15 μm or less. Claims 1 to 12 and 14
The laminated packaging material described in any of the paragraphs. (g) The surface layer according to any one of claims 1 to 15, wherein the surface layer includes at least one layer selected from a linear low-density polyethylene layer and an ethylene-vinyl acetate copolymer layer. Laminated packaging material. Claims 1 to 16, wherein at least one of the a-force surface layers is a layer made of linear low-density polyethylene containing an α-olefin having 4 or more carbon atoms as a copolymerization component. Laminated packaging material. (1) At least one of the surface layers has a heat of fusion of 25C, al19 or less based on thermal analysis using a differential scanning calorimeter.
The laminated packaging material according to any one of claims 1 to 17, which is a layer made of Km-shaped low-density modified polyethylene. At least one side of the 01 surface layer contains butene-1 as a copolymerized component, and the heat of fusion is 35% based on thermal analysis using a differential scanning calorimeter.
The laminated packaging material according to any one of claims 1 to 16, which is a layer made of linear low-density polyethylene having a calf/9 or less. At least one of the gradient surface layers has a Young's modulus of 2 at 20°C.
The laminated packaging material according to any one of claims 1 to 18, which is a layer made of linear low-density polyethylene having a weight of 2 kg/- or less. 21) At least one of the surface layers is a layer made of linear low-density polyethylene containing butene-1 as a copolymer component and having a Young's modulus of 12 Kq/mA or less at 20° C. Sections 16, 18 and 19
The laminated packaging material described in any of the paragraphs. @At least one of the surface layers is a layer made of linear low-density polyethylene containing an α-olefin having 5 or more carbon atoms as a copolymer component.Claims 1 to 16, 1
The laminated packaging material according to any one of Items 8 and 20. Claims 1 to 16, 18, and 18, wherein at least one of the rut surface layers is a layer made of linear low-density polyethylene containing 4-methyl-]-pentene as a copolymer component. The laminated packaging material according to any of Item 20. (to) The laminated packaging material according to any one of claims 1 to 16, wherein at least one of the surface layers is a layer made of an ethylene-vinyl acetate copolymer containing 7% by weight or more of vinyl acetate. . 25. The laminated packaging material according to any one of claims 1 to 24, wherein the laminated packaging material is a constituent material of a packaging container in which the packaging filler is an aqueous mixture or a water-containing substance. (to) The laminated packaging material according to any one of claims 1 to 25, wherein the packaging material is a constituent material of a bag-in-box inner container.