CA2035572A1 - Resin composition and use thereof - Google Patents

Abstract

PATENT APPLICATION
Country : JAPON
No. : 23018 Filed on : 1st February 1990 File : AM 0470 A B S T R A C T
RESIN COMPOSITION AND USE THEREOF

Company called : ATOCHEM
4 & 8 Cours Michelet La Défense 10 Authorized agent : Pierre POISSON

Inventors : Takamasa MORIYAMA
Hiroyuki HONDA
Hiroshi TAKIDA
The present invention relates to a composition with a gaz bar-rier property comprising :
- a saponified ethylene-vinyl acetate copolymer, - a polyolefin resin, - a compatibilizing agent defined in the description and - a hydrotalcite solid solution representable by the general formula [(M2+)yl(M2+)y2]1-xM3+(OH)2Ax/n.mH2O
wherein M2+ represents at least one metal selected from among Mg, Ca, Sr and Ba, M2+ is a metal selected from among Zn, Cd, Pb and Sn, M3+ is a trivalent metal, An- is an anion having a valence of n, and x, y1, y2 and m are respectively positive numbers satisfying the conditions 0 < x ? 0.5, 0.5 < y1 < 1 < y1 + y2 = 1, and 0 ? m < 2.
This composition can be used for the manufacture of film usable for packaging.

Description

3. Detailed Description of the Invention [Industrial Field of Utilization]
The present invention provides a saponified ethylene-vinyl acetate copolymer composition markedly improved in long run property in melt-molding and in quality.
~Prior Art]
Saponified etnylene-vinyl acetate copolymers are excellént in variols properties such as oxygen barrier property, mechanical strength, etc., and therefore have found application _n various uses such as film, sheet, container material, textile fiber and so on.
However, since such saponified copolymers are highly hygroscopic, shaped articles based on these materials are disadvantageous in that they undergo marked change in p;~ysical properties such as flexibility according to changes in the humidity and temperature of the ambient atmospnere and, in particular, their oxygen barrier property s so highly dependent on humidity that they do not effectively seal off oxygen in a high-humidity env_ron~ent.

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Furthermore, because of poor stretchability and flexibility, shaped articles based on this type of copolymer readily undergo uneven stretching in the course of deep-drawing or other molding procedures involving stretchinq and/or give pinholes in use after molding, imposing limitatlons on their use as packaging materials. Therefore a polyolefin resin is often admixed with said saponified copolymers.
However, such resin mixtures as mentioned above are inferior in the so-called long run property. ~hen they are used to produce films, sheets and the like shaped articles by melt-molding, for instance, said mixture compositions undergo gelation during molding and/or give, during molding, thermally discolored or carbonized resins (the so-called scorches), which adhere to the extruder inside. Accordingly the melt molding cannot be done continuously for a prolonged period of time. To cope with this probiem, the com-bined use of a hydrotalcite solid solution has been proposed as a measure therefor.
[Problems which the Invention is to solve]
Recent technological innovations and social needs for higher quality snaped articles have emphasized the necessity of developing novel saponified ethylene-~inyl acetate copolymer compositions much more improved than ~3~ 2 the conventional ones.
More specifically, the prior art compositions are often used in the form of laminates with a polyolefin or polyester or the like thermoplastic resin. When exposed to a high-temperature high-humidity atmosphere, . the laminates in the form of packaging materials for retortable foods, or instance, often undergo decrease in interlayer adhesion, which may lead to the occur-rence of the phenomenon of peeling or whitening (blush-ing). Development of improved compositions is strongly demanded.
[Means for Solving ,he Problems]
The inventors of the present invention made intensive investigations in an attempt to develop a saponified ethylene-vinyl acetate copolymer composition having excellent long run property and ensuring higher quality characteristics as compared with the conven-tional compositions, for example markedly improved interlayer adhesion, among others, even in a high-temperature high-h~midity atmosphere, with the oxygen barrier property in~rinsic of the saponified copolymer being retained at a high level. As a result, they found that the objects such as mentioned above can be accomplished by a ~esin composition which comprises (A) a saponified ethylene-vinyl acetate copolymer, ~B) a polyolefin resin, (C) A graft polymer obtained by grafting an ethylenic-ally unsaturated carboxylic acid or a derivative thereof to a polyolefin resin and reacting the adduct with a polyamide oligomer, and (D~ a hydrotalcite solid solution representable by the general formula )yl(M )y2]1-xr~ (oH)2Ax/n~mH2o wherein M2+ represents at least one metal selected from among Mg, Ca, Sr and Ba, M2 is a metal selected from among Zn, Cd, Pb and Sn, M3 is a trivalent metal, An is an anion having a valence of n, and. x, yl, y2 and m are respectively positive numbers satisfying the conditions 0 < x ' 0.5, 0.5 < yl < 1, yl + y2 = 1, and 0 S m < 2. The present invention has been completed based on the above finding.
The present invention will hereinafter be de-scribed in detail, with emphasis placed on such composi-tion and, in particular, on uses for shaped articles based thereon.
The saponified ethylene-vinyl acetate copolymer ~A) to be employed in accordance with the present invention should have an ethylene content of 2Q to 60 mole %, preferably 25 to 55 mole %, with a degree of saponification of its vinyl acetate component being not less than 95 mole %.
With an ethylene content less than 20 moie %, the oxygen barrier property under high-humidity conditions is not as high as desired, while an ethylene content in excess of 60 mole % leads to decreases in o~gen barrier property, printability and other phys-cal properties. When the degree of saponificatiGn or hydrolysis is less than 95 mole %, the oxygen barrier property and moisture resistance are sacrificed.
It should be understood that this sapon~ ied copolymer may contain small proportions of o~;.er comonomer ingredients including a-olefins such as propylene, isobutene, a-octene, a-dodecene, ~-octa-decene, etc., unsatura~ed carboxylic acids o_ salts thereof, partial alkyl esters, complete alkyl esters, nitriles, amides and anhydrides and unsatura__d sulfon-ic acids or salts thereof.
With regard to the above component (A), -ts melt flow rate (hereinafter referred to briefly as ;~FR) M
as determined at 210C and under a load of G ~O g according to JIS K-6760 is suitably in the range of 0.5 to 100 g/lO minutes and preferably 1 to 60 g/:0 minutes.
With regard to the polyolefin resin (~), there may be mentioned linear low-density polyethylene, low-, ~3~

medium- and high-density polyethylenes, ionomers, ethylene-propylene copolymer, crystalline polypropyl-ene, polybutene, ethylene-vinyl acetate copolymer of comparatively low vinyl acetate content, and so on.
Particularly, low-, medium- or high-density polyethyl-ene, and isotactic polypropylene are of practical importance.
With regard to (B~, it is advantageous that its melt flow rate as determined at 210C and under a load of 2160 g according to JIS ~-6760 is in the range of 0.01 to 100 g/10 minutes.
~ or improving the compatibility among the components of the desired resin composition, incorporation of (C) is essential in the practice of the invention.
The component (C) is a graft polymer obtainable by grafting an ethylenically unsaturated carboxylic acid or a derivative thereof to a polyolefin resin and reacting this carboxylic acid or derivative thereof with a polyamide oligomer.
This graft polymer can be produced by dissolving or suspending a polyolefin resin in an appropriate sol-vent or putting it in a molten state, activating the poly-olefin resin chain with a peroxide or diazo initiator, grafting an ethylenically unsaturated carboxylic acid or a 2 ~ ~ 3~

derivative thereof thereto to give a polymer and mixing this polymer with a polyamide oliyomer in molten state.
For this reaction, Brabender machine, Buss blender, s-ngle-screw extruder, Werner and ~fleiderer twin-screw extruder or the like is employed.
- The degree of polymerization of the polyolefin resin to be employed is about 350 to 45,000 and prefer-ably about 500 to 10,000. The melt flow rate ~230C, load 2160 g; the same applies hereinafter) is about 0.1 to 50 g/10 minutes for all practical purposes.
~ he reaction ratio of the polyolefin resin to the ethylenically unsaturated carboxylic acid or a derlva-tive thereof is 100/0.05 through 100/10 and preferably 100/0.5 through 100/3 as expressed on the weight basis.
If the ratio is 100/less than 0.05, the improving effect on compatibility will not be sufficient. On the other hand, if the ratio is 100/more than 10, the viscosity will be too high for practical molding.
The degree of polymerization of said polyamide oligomer is 5 to 80, preferably about 15 to 55, for all practical purposes and the reaction ratio is 0.01 to 1 mole and preferably 0.05 to 0.9 mole per mole of the carboxyl group.
As examples of the polyolefin resin, there may be mentioned linear low-density, low-density, medium-density or high-density polyethylene, ionomers, ethyl-ene-propylene copolymer, crystalline polypropylene, polybutene, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer and so on. Important for practical purposes are linear low-density polyethylene, low-density polyethylene, high-density polyethylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer and crystalline polypropylene.
The ethylenically unsaturated carboxylic acid or derivative thereof to be grafted to such a trunk polymer includes, among others, unsaturated carboxylic acids such as acrylic acid, methacrylic acld, crotonic acid, maleic acid, fumaric acid and itaconic acid, and the corresponding anhydrides or half esters.
The polyamide oligomer can be prepared by the known methods such as addition polymerization of a lactam, polycondensation of an aminocarboxylic acid, polycondensation of a diamine with a dicarboxylic acid, and so on.
~ xamples of the starting materials for said polyamide oligomer are various lactams such as ~-capro-lactam, enantholactam, caprylolactam, laurolactam, a-pyrrolidone, a-piperidone, etc., ~-amino acids such as 6-aminocaproic acid, 7-aminoheptanoic acid, 9-amino-nonanoic acid, 11-aminoundecanoic acid, etc., dibasic g acids such as adipic acid, glutaric acid, pimellic acid, suberlc acid, azelaic acid, sebacic acid, un-decadioic acid, dodecadioic acid, hexadecadioic acid, hexadecenedioic acid, eicosadioic acid, eicosadiene-dioic acid, diglycolic acid, 2,2,4-trimethyladipic acid, xylylenedicarboxylic acid, 1,4-cyclohexanedi-carboxylic acid, terephthalic acid, isophthalic acid, etc., and diamines such as hexamethylenediamine, tetramethylenediamine, nonamethylenediamine, undeca-methylenediamine, dodecamethylenediamine, 2,2,4- (or 2,4,4-)trimethylhexamethylenediamine, bis(4,4'-amino-cyclohexyl)methane, metaxylylenediamine and so on. For molecular weight control, a monoamine such as lauryl-amine or oleylamine can also be used in an appropriate amount.
In the composition of the present invention, the proportion of (A) should be 50 to g9.5 weight O and preferably 60 to 95 weight %, that of (B) should be 0.4 to 50 weight % and preferably 4.5 to 35 weight -0, and that of (C) should be 0.1 to 15 weight ~ and preferably 1.5 to 10 weight %.
When the proportion of (A) is less than 50 weight % or that of (B) is over 50 weight %, the oxygen barrier property is adversely affected. Conversely when the proportion of ~A) is over 99.5 weight % or that of (B) is less than 0.4 weight ~, stretchability and flexibility are sacrificed. When the proportion of (C) is less than 0.1 weight %, the compatibility between (A) and (B) is poor, so that the interlayer adhesion of laminates decreases. Conversely when the proportion of (C) exceeds 15 weight %, long-run mold-ability is adversely affected.
The component (D) to be employed in accordance with the present invention is a hydrotalcite solid solution representable by the general formula [( )yl(M )y2]1-xM (OH)2Ax~n.mH2o wherein M2 represents at least one metal selected from among Mg, Ca, Sr and Ba, M2 is a metal selected from among Zn, Cd, Pb and Sn, M3+ is a trivalent metal, An is an anion having a valence of n, and x, yl, y2 and m are respectively positive numbers satisfying the conditions O ~ x ' 0.5, 0.5 < yl < 1, yl + y2 = 1, and O ~ m < 2.
With regard to the above general formula, M2 is preferably Mg or Ca and M2 is desirably Zn or Cd. M3+
includes, as examples thereof, Al, Bi, In, Sb, B, Ga and Ti. Among them, Al is suited for practical use.
Useful as A are C03 , OH , HC03 , salicylate ion, citrate ion, tartrate ion, N03 , I , oxalate ion, [Fe(CN)6]4 , Cl04 , CH3COO , maleate ion and the like.

:

The hydrotalcite solid solution may be surface-treated with a higher fatty acid, anionic surfactant, silane coupline agent, titanate coupling agent, glycerin fatty acid ester or the like.
Typical examples of (D) are as follows:
0-75 0.25]0.67Al0.33(H)2(C3)0 165--45H2 [MgO 79Zno 21]0 7Alo.3( OH)2(co3)o.15 1/7 3/7 3/7]o.7Alo.3(oH)2(cHcoo) o.4lH2o CHCOO o 15 [ g6/7Cdl/7]0.7P~l0.3(0H)2(cH3coo)o 3-0.34H20 [Mg5/7pb2/7]o 7Alo 3(0H)2(C03)o 15-0.52H20 [ gO.74zno.26]o.68Alo 32(H)2(C3)0 16 0-56 0.44]0.68A10.32(0H)2(Co3)0 16-o-2H2o [ go.8lzno.ls]o.74Alo.26(oH)2(co3)o 13 0-75 3-25]0.8AlQ.2(oH)2(co3)0 1o-0.16H20 [MgO 71ZnO 29]0.7Al0.3(H)2( 3)0-30 [Mg0.7lzno.29]o.7 10.3( )2(11 ) CHC 0.15 [ gO .14CaO . 57ZnO . 29 ] 0 - 7A10 3 ~ OH~ 2 3 25H2o The component (D) is used in an amount of 0.005 to 5 parts by weight, prefexably 0.01 to 1 part by weight, per 100 parts by weight of the sum total of (A) plus (B) plus (C).

When the amount of (D) is smaller than O.005 part by weight, the long-run moldability is low while films . - 12 -2~3~7~

will have decreased transparency, stretchability and flexibllity when said amount exceeds 5 parts by weight.
The component ~D) may be present in any form in the mixture of (A), (BJ and (C~. The time of addition of (D) is not critical. It is advantageous, however, to admix (D) with the polyolefin resin (B) in advance and then blend the masterbatch-like mixture with the components (A) and (C).
While the composition according to the present invention is useful for a variety of applications such as shaped articles, adhesives, coatings and so on, it is most useful for molding purposes and can be molded into pellets, film, sheet, containers, fibers, bars, pipe and other shaped articles by the melt-kneading technique. Such products can be crushed (for reclaim-ing) or pelleted for re-melt-molding.
For melt-molding of the composition, extrusion molding ~e.g. T-die extrusion, inflation molding, blow molding, melt spinning or contour extrusion) and injection molding are mostly employed. The melt-molding temperature is selected in many cases from the range of 170 to 270C. In addition to the above techniques, two-color molding and injection-blow molding techniques may also be employed and shaped articles with good dimensional tolerances can be 2 ~ 3 ~

manufactured.
In the molding process, it is of course possible to use two or more different saponified ethylene-vinyl acetate copolymers varying in ethylene content and/or in the degree of saponification in combination. In melt-molding, it is also possible to incorporate, besides the above-mentioned saponified ethylene-vinyl acetate copolymer, suitable amounts of additives such as a plasticizer (for example, a polyhydric alcohol), stabilizer, surfactant, crosslinking agent (for example, an epoxy compound, polyvalent metal salt, inorganic or organic polybasic acid or salt thereof), filler, colorant, reinforcing fiber ~for example, glass fiber, carbon fiber, etc.), and so on. Any other thermo-plastic resin may also be incorporated. Such thermo-plastic resin includes, among others, polyolefins other than the component (B) mentioned above (linear low-density, low-density or high-density polyethylene, polypropylene, ethylene-propylene copolymer, ethyl-ene-propylene-diene copolymers, copolymers of ethylene and an alpha-olefin containing 4 or more carbon atoms, ethylene-vinyl acetate copolymer, ethylene-acrylate ester copolymers, ionomers, polybutene, polypentene, etc.), modified polyolefins obtainable by graft-modi-fication of such polyolefins with unsaturated carboxylic ~ ~ ~ 3 acids or derivatives thereof, polyamides, polyvinyl chloride, polyvinylidene chloride, polyesters, poly-styrene, polyacrylonitrile, polyurethanes, polyacetal, polycarbonates, melt-moldable polyvinyl alcohol resin and so on.
As mentioned hereinbefore, the composition of the present invention is not only used for the manufacture of a single-layer article solely composed of the composition but also used often as a laminated article including at least one layer of the composition.
The layer of the composition of the present invention shows a characteristically high bonding affinity for the layer material to be laminated there-with. In particular, said bonding affinity can be retained at a high level even under high-temperature high-humidity conditions in retorts and the like.
In the manufacture of a laminated product accord-ing to the invention, in which a different material is laminated to one side or either side of a layer of the composition of the invention, the following laminating methods, for instance, can be employed. Thus, the method which comprises melt-extruding a thermoplastic resin onto a film or sheet of the composition of the invention, the method which comprises melt-extruding the composition of the invention onto a substrate made 2~3~ 7~

of a thermoplastic resin or some other material, the method which comprises co-extruding the composition of the invention and a different thermoplastic resin, and the method in which a film or sheet of the composition of the invention is laminated to a film or sheet of a different material with a known adhesive such as an organotitanium compound, an isocyanate compound or a polyester compound can be mentioned.
As mating resins for co-extrusion, there may be mentioned linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ionomers, ethylene-a-olefin (C3 20 a-olefin) copolymers, ethylene-acrylic ester copolymers, polypropylene, propylene-a-olefin (C4 20 a-olefin) copolymers, homo- or copolymers of olefins such as polybutene, polypentene, etc., and polyolefin resins in a broad sense as obtainable by modifying such homopolymers or copolymers of olefins by grafting of an unsaturated carboxylic acid or an ester thereof, polyesters, polyamides, copolymerized poly-amides, polyvinyl chloride, polyvinylidene chloride, acrylic resins, styrenic resins, vinyl ester resin, polyester elastomers, polyurethane elastomers, chlo-rinated polyethylene, chlorinated polypropylene and so on. A saponified ethylene-vinyl acetate copolymer can 2 ~ ?~ a~ J

also be co-extruded.
When a film or sheet or the like shaped article is prepared from the composition of the invention and, then, extrusion-coated with a different material or laminated to a film or sheet of a different material with an adhesive, said different material is not limited to said thermoplastic resins but may be vir-tually any other material (such as paper, metal foil, uniaxially or biaxially oriented plastic film or sheet, woven fabric, nonwoven fabric, metal filament, wood and so on).
The laminar structure of sald laminated product is optional. Thus, a layer of the composition of the invention being designated as A (A1, A2, ) and a layer of a different material, e.g. a thermoplastic resin, being designated as B (B1, B2, ), not only a two-layer structure of A/B but a variety of other combinations such as B/A/B, A/B/A, A1/A2/B, A/B1/B2, B/A/B, B2/B1/A/B1/B2, etc. can be employed for a film, sheet or bottle, for instance. In the case of a filament, a bimetal-type, core (A) - sheath (B), core (B) - sheath (A), eccentric core-sheath and other combinations of A and B can be adopted.
For co-extrusion, A may be blended with B or vice versa, or for improved interlayer adhesion, a suitable ~$~Jc~s 2 resin may be incorporated in at least one of A and B.
The laminated product may be optionally configured.
Thus, film, sheet, tape, bottle, pipe, filament, or modified cross-section extrudate may be mentioned.
The laminated product may, if necessary, ~e further subjected to a variety of processings, such as heat treatment, cooling, rollinq, printing, dry lamina-tlon, solution- or melt-coating, bag production, deep-drawing, box-making, tubing, splitting and so on.
The aforementioned shaped articles and laminated products, in particular in the form of film or sheet, can be improved in physical properties by stretching or drafting, if required.
In the present invention, the composition is melt-molded into a film material. The thickness of such film is virtually optional and may range from a few microns to several hundred microns. The term 'film' as used in this specification means a film in the broad sense of the term, thus including a sheet, tape, tube, container and so on.
The film obtained in the above manner is condi-tioned for absorption of moisture or drying, if neces-sary, and then stretched.
This stretching may be uniaxial or biaxial. The effects of the invention are better materialized when 2 ~

the stretching ratio or draft is as high as possible.
In the case of uniaxial stretching, the stretching ratio is preferably at least 1.5 times and, for still better results, not less than 2 times. In the case of biaxial stretching, the stretching ratio is preferably not less than 1.5 times, more desirably not less than 2 times and, for still better results, not less than 4 times on the area basis.
As to the stretching technique that can be em-ployed, there may be mentioned roll stretching, tenter stretching, tubular stretching and stretching blow processes, as well as high-draft deep drawing or vacuum molding. In the case of biaxial stretching, whichever of concurrent biaxial stretching and serial biaxial stretching can be adopted.
The stretching temperature is selected from the range OI about 40 to 150C.
After completion of stretching, the product is thermally set. This thermal setting can be effected by the well-known technique. Thus, with the stretched film being held in taut condition, it is heat-treated at a temperature of S0 to 160C, preferably at 80 to 160C for about 2 to 600 seconds.
The resulting oriented film can be subjected to a variety of processings such as cooling, rolling, ~ ~3 C~S ~ 'J i ~

printing, dry lamination, solution- or melt-coating, bag-making, deep-drawing, box-making, tubing, splitting and so on.
The film, sheet or container obtainable from the composition of the present invention is useful for packaging foodstuffs, pharmaceutical products, in-dustrial chemicals, agrochemical products and so on.
[Effects]
The composition according to the invention which comprises (A), (B~, (C) and (D) is excellent in long run property and the shaped articles obtained therefrom are characterized by their markedly improved interlayer adhesion, oxygen barrier property, stretcha~sility and flexibility.
[Examples]
The following examples are further illustrative of the composition of the present invention. In the following description, all parts and % are by weight unless otherwise indicated.

2~33~ 7~

Saponified ethYlene-vinyl acetate co~olYmer Sample E-l E-2 E-3 E-4 Ethylene content 30 33 40 45 (~ole %) Degree of saponification of vinyl acetate component 99.4 99.1 99.6 99.7 (mole ~) Polyolefin resin MFR Melting point Sampie l jlO min.) (C) P-l Polypropyiene 3 166 P-2 Ethylene-propylene ~lock copolymer 5 163 (Ethylene content 12~) P-3 Ethylene-propylene rando~ copolymer 8 165 (Ethylene content 3%) P-4 Polypropylene 8 166 P-5 Linear low-density polyethylene 4 124 _ P-6 High-density polyethylene 1.2 134 ~ Y~1 ~ J ~3 .~ S' E a~ a~
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0 C 0 .R _ ~ E v v h ~c 0 O ~ O ~1 0 -- o u~ h 2~ 3 ~ 2 Hydrotalcite solid solution H-1 [MgO 75ZnO 25]0 67Alo.33(H)2(C03)0.165 2 [ g6/7Cdl~7]0 7Alo 3~H)2(CH3C)O 3~0.34H ~
91/7 a3/7Zn3/7]0.7AlO 3(0H)2~cHcoo) 0.41H O
\CHCOO O 15 H-4: [Mg5/7Pb2/7]o 7Alo 3(0H)2(Co3)o.ls 2 Examples 1 through 10 and Comparative ExamPles 1 and 2 Laminates having the construction shown below were produced using the compositions comprising a combination of (A), (B), (C) and (D) as specified in Table 1.
Outer layer (I): Polyamide 6.
Intermediate layer (II): Composition according to the invention comprising (A), (B), (C) and (D).
Adhesive layer (III): Maleic anhydride-modified ethylene-vinyl acetate copolymer [MFR: 2.1 g/10 minutes (190C, 2160 g)].
Inner layer ~IV): Ethylene-vinyl acetate copolymer with a vinyl acetate content of 10%
- [MFR: 2 g/10 minutes (l90~C, 2160 g)].
Four-layer laminates with layer thicknesses of (I)/(II)/(III)/(IV)=20/10/5/20 microns. For stretchability testing, f~lms with layer thicknesses 80/40/20/80 microns were used.
Extrusion modlinq conditions - ~3~v~

Extruder:
40 mm-dia. extruder (for inner layer) 40 mm-dia. extruder (for intermediate layer) 30 mm-dia. extruder (for adhesive layer) 40 mm-dia. extruder (for outer layer) Screw: For each, L/C = 2.8; compression ratio =

3.2 Speed of screw revolution:
For inner layer : 40 rpm For intermediate layer: 20 rpm For adhesive layer : 20 rpm For outer layer : 40 rpm Die:
T-Die with a 4-layer combining adapter Die width: 450 mm Extrusion temperature:
Extruders for inner, outer and adhesive layers C1 = 190C, C2 = 200C, C3 = 210C, C4 = 220C
Extruder ior intermediate layer C1 = 180C, t2 = 200C, C3 = 220C, C4 = 220C
Combining adapter: 210C
T die : 210C

2 ~

The results obtained are shown in Table 1.
The bond strength was measured after retort treatment (120C x 30 minutes).
The long-run property was evaluated after 96 hours of continuous extrusion molding, followed by disjointing of the extruder, in terms of the state of gel adhesion on the screen mesh as rated on the 5-point scale from 1 (no adhesion) to 5 (adhesion on the whole surface) or the state of adhesion of a scorched or burnt material on the screw surface as rated on the 5-point scale from 1 (no adhesion) to 5 (adhesion on the whole surface).
The oxygen permeability was determined with a MOCON Oxtran 10/50. The stretchability was evaluated in terms of uneven stretching in simultaneous biaxial stretching (3 x 3 times) at 90C.
The film impact strength was determined using a film impact tester (impact head diameter 3/2 inches, 20C x 65% RH).
The resistance to flexural fatigue was evaluated in terms of the number of bendings until formation of one pinhole (until an abrupt increase in oxygen per~
meability) with a Gelboflex tester.

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E~ C ~ ou O ~ v c~ u ~ ~ ~ ~J

o ~ v C ~

0 ~ vl ~ ~ O r~
L" r~l r o la 5~ r~ ~ rl ~ r~ r ~ ~ , _l ~ ~
ra kl ~ ~ ~ O
. _~ ~ _ E E~ u~ X
~; ~ . ~

Examples 11 through 15 Inner layer (I) and outer layer (V): Linear low-density polyethylene (MFR 1.5 g/10 minutes, density 0.920) Adhesi~e layers (II) and (IV): Maleic anhydride-modified linear low density polyethylene (MFR
2 g/10 minutes) Intermediate layer (III): Composition according to the invention comprising (A), (~), (C) and (D).
Layer Composition and layer thicknesses (microns):
(I)/(II)/(III)/(IV)/(V) = 20/5/10/5/20 For stretchability testing, the layer thicknesses 80/20/40/20/80 were used.
Extruder:
40 mm-dia. ex~ruder (for inner and outer layers) 40 mm-dia. extruder (for intermediate layer) 30 mm-dia. extruder (for adhesive layers) Screw: For each, L/D = 28, compression ratio = 3.2 Speed of screw revolution:
For inner and outer layers: 65 rpm For intermediate layer: 20 rpm For adhesive layers: 30 rpm.
Die:
T-Die with a 5-layer combining adapter 2 ~ 3 ~ e~ ~ ~

Die width: 450 mm Extrusion temperature:
Extruders for inner, outer and adhesive layers C1 = 190C, C2 = 200C, C3 = 210C, C4 = 220C, Extruder for intermediate layer . ' C1 = 180C, C2 = 200C, C3 = 220C, C4 = 220C, Combining adapter 210C
T die 210C
The results obtained are shown in Table 2.

. - 29 -~, ~ o o o o o 2 ~ r3 ~ ~
~ a) ~ ~ o o o o o Q)O~- ~ ~ ~7 ~ ~

v ~ E o o u) In o a~ U r~ _ _ ~ tt~
~ ~,_ 0~ 0~ O Ln 1n ~
.` ~ ~
~ ~' ~ ~ ~ ~ ~

e 1 U ~ _ _ ~ ~`J
~ ~U~

.` ~ S~ ~3 h :~ V L~ U ~ _ t~1 r~l _ 4~ ~'0 ~1 t~ ~q E ~1 _ ~ _ .~ O o . ' v ~ O + 'n ~ ~ o rl 1~ ~ + o o o o o ~ ~ o o u7 ~ ~ m ~n r ~ r r s~ _ _ ~ ~ ~ r) r~l r~ rl ~ ~ r~ ~r ~ ~ _~
)a ~1.7 ~ ~ ~~ ~ ~7 T ~ ~ ~7 'r ~ ) ~ ~ ~L ~7 _ _ r~ _ n ~3~

[Effect~
The composition according to the invention which comprises (A) a saponified ethylene-vinyl acetate copolymer, (B) a polyolefin resin, (C) a specific graft copolymer and (D) a hydrotalcite solid solution is excellent in long-run processability and gives shaped articles having good oxygen barrier property, stretch-ability and flexibility.

Claims (4)

1. A resin composition which comprises (A) a saponified ethylene-vinyl acetate copolymer, (B) a polyolefin resin, (C) a graft polymer obtained by grafting an ethylenic-ally unsaturated carboxylic acid or a derivative thereof to a polyolefin resin and reacting the adduct with a polyamide oligomer, and (D) a hydrotalcite solid solution representable by the general formula [(M2+)y1(M2+)y2]1-XM3+(OH)2Ax/nmH2o wherein M2+ represents at least one metal selected from among Mg, Ca, Sr and Ba, M2+ is a metal selected from among Zn, Cd, Pb and Sn, M3+ is a trivalent metal, An is an anion having a valence of n, and x, y1, y2 and m are respectively positive numbers satisfying the conditions 0 < x ? 0.5, 0.5 < y1 < 1, y1 + y2 = 1, and 0 ? m < 2.

2. A shaped article obtained by melt-molding a composition as claimed in Claim 1.

3. A laminated structure at least one layer of which is comprised of a composition as claimed in Claim

4. A shaped article as claimed in Claim 2 or a laminated structure as claimed in Claim 3 which is at least uniaxially oriented.