JPH08165397A - Resin composition and use thereof - Google Patents

Abstract

PURPOSE: To prepare a resin compsn. having excellent resistance to flexural fatigue impact resistance, excellent gas barrier properties and other properties by extruding a saponification product of an ethylene/vinyl acetate copolymer (abbreviated to 'EVOH'), a polyolefin resin, and a polyolefin resin modified with a carboxylic acid under particular conditions. CONSTITUTION: This resin compsn. comprises (A) EVOH having an ethylene content of 20 to 60mol% and a degree of saponification of not less than 90mol%, (B) a polyolefin resin, and (C) a polyolefin resin modified with a carboxylic acid. In melt-mixing of the component (A) with a premixed component (B+C), extrusion is conducted at a specific energy (E1 ) per L/D unit of not more than 0.020kW.hr/kg at the time of extrusion, wherein L represents the length of a screw of an extruder (mm) and D represents the diameter of the screw (mm).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition prepared by blending a saponified ethylene-vinyl acetate copolymer (hereinafter abbreviated as EVOH) with a polymer alloy of a polyolefin resin and its use. is there.

[0002]

2. Description of the Related Art Conventionally, blends of EVOH and polyolefin resins have been used for various films, containers, etc. by taking advantage of EVOH gas barrier properties, polyolefin resin moldability, stretchability, crack resistance and the like. It is used for molded products. However, since the blended product is composed of two components, there are problems at the time of new molding and physical properties. In recent years, in order to solve these problems, it has been attempted to blend EVOH with a modified polyolefin resin, an alkaline earth metal or the like.

For example, in Japanese Unexamined Patent Publication No. 5-255555, conventional characteristics are impaired with respect to characteristics such as flexural fatigue resistance, stretchability, impact resistance, flexibility, gas barrier property, color resistance and gelation prevention performance. For the purpose of obtaining a resin composition with good productivity that does not cause film breakage during high-speed molding of a film, (A) EVOH, (B) polyolefin-based resin, (C) carboxylic acid-modified polyolefin-based resin, and ( D) At least one compound selected from the group consisting of alkali metal or alkaline earth metal salts, oxides and hydroxides is blended. In addition, JP-A-6-1362
In JP 06-06, EVOH and acid-modified polyolefin are melt-mixed for the purpose of obtaining an acid-modified polyolefin resin composition having good adhesion to polyolefin, EVOH and the like,
The specific energy during the melt mixing is 0.3 kW · hr
/ Kg or more is proposed.

On the other hand, the blend of EVOH and polyolefin resin is applied to the inner container for back-in-box by making the best use of the respective characteristics of EVOH and polyolefin resin as described above. For example, JP-A-6-1066
In Japanese Patent Publication No. 86, a layer of a resin composition in which EVOH and a polyolefin resin are melt-mixed is used as an intermediate layer, an adhesive layer is provided on both sides of the intermediate layer, and a surface layer is provided outside the adhesive layer. It is proposed that, by using the configuration, a back-in-box inner container having an excellent gas barrier property can be obtained for a long time without cracks in the laminate punching process at the time of manufacturing the liquid injection port of the inner container. There is.

[0005]

However, according to the detailed study by the present inventors, the above-mentioned Japanese Patent Laid-Open No. 25555/1993.
According to the technique disclosed in Japanese Patent Publication No. 5, the breakage of the film of the blend film of EVOH and the polyolefin-based resin at high speed can be reduced, and a resin composition with good productivity is obtained, but the obtained molded product is obtained. In terms of physical properties such as flexibility, gas barrier property, impact resistance, and bending fatigue resistance, it has the performance to withstand practical use,
Molding stability, for example, there is also a problem that the above-mentioned physical properties vary depending on the location used for the molded film, and further, gel may occur frequently due to the influence of processing conditions. Further improvement of molded products is desired.

Regarding the technique disclosed in JP-A-6-136206, a resin composition having improved adhesiveness is obtained by melt-mixing an acid-modified polyolefin resin and EVOH at a specific energy of 0.3 kW · hr / kg or more. However, no consideration is given to other physical properties such as gelation prevention, impact resistance, and bending fatigue resistance. In addition, JP-A-6
As for the inner container for back-in-box disclosed in Japanese Patent Laid-Open No. 106686, as a result of detailed examination, there are problems such as variations in physical properties such as bending fatigue resistance and crack resistance, as described above. There is still room for improvement.

As described above, with the recent improvement in the required performance, not only the blend shows a high physical property value but also the impact resistance and the flex fatigue resistance are excellent, and the gel is stable and stable. It has been desired to develop a resin composition for obtaining a molded product such as a film or sheet having the above physical properties. In particular,
A resin composition having excellent impact resistance, bending fatigue resistance, and gelation resistance is very useful for applications such as an inner container for a back-in-box or a cushioning material having a hollow chamber, and is highly expected.

[0008]

Therefore, the present inventors
As a result of a detailed study on a resin composition comprising VOH and a polyolefin-based resin, it is possible to obtain a stable film or sheet which is excellent in bending fatigue resistance and impact resistance by adopting a specific mixing and melting method, and which does not cause gelation. The present invention has been completed by finding out the new fact that the above resin molded product can be obtained.

That is, to solve the above problems, (A) an ethylene-vinyl acetate copolymer saponified product having an ethylene content of 20 to 60 mol% and a saponification degree of 90 mol% or more, (B) a polyolefin resin, (C) A carboxylic acid-modified polyolefin resin, which is premixed with (A) [(B)
+ (C)] is melt-mixed in an extruder, the screw length of the extruder is L (mm) and the diameter is D (m).
m), the specific energy (E ₁ ) during extrusion per L / D unit is 0.020 kW · hr / kg or less, preferably 0.018 kW · hr / kg or less. There is the greatest feature of the present invention in this respect.

Here, the specific energy means the energy given to the resin per unit discharge amount (1 kg) from the kneading equipment for the effect of kneading when the resin is melted and kneaded, and an ammeter is applied to the motor of the extruder. , Attach a voltmeter,
It is defined by obtaining the electric power consumption of the motor from this, multiplying this by the power factor of the motor (usually about 0.85), and calculating the amount of electric power per discharge amount. It is obtained by the difference between the specific energy and the specific energy during idling.

In the present invention, when [(B) + (C)] is melt-mixed in advance with an extruder, the screw length of the extruder is L (mm) and the diameter is D (mm). The specific energy (E ₂ ) at the time of extrusion per L / D unit
Is particularly superior when (A) is larger than the specific energy (E ₁ ) at the time of extrusion per L / D unit when melt-mixing (A) and [(B) + (C)] that have been mixed in advance. The effect of the present invention is shown. Further, the resin composition of the present invention is an inner container for a back-in-box, wherein the resin composition is used as an intermediate layer, an adhesive layer is provided on both sides of the intermediate layer, and a surface layer is provided outside the adhesive layer, or It is suitable for use as a cushioning material having a hollow chamber containing at least one layer of the resin composition. Hereinafter, the present invention will be described in detail.

As EVOH (A) used in the present invention,
The ethylene content is 20 to 60 mol%, preferably 25 to 5
5 mol%, saponification degree of 90 mol% or more, preferably 99
Mol% or more, melt index (210 ° C, load 21
60 g) is 1 to 100 g / 10 minutes, preferably 3 to 50
G / 10 min is used.

When the ethylene content is less than the above range, the molding temperature and the decomposition temperature are close to each other, making molding difficult, and when the ethylene content is more than the above range, the gas barrier property tends to be lowered. . When the saponification degree is smaller than the lower limit value, the gas barrier property is deteriorated. Further, when the melt index is smaller than the above range, the inside of the extruder is in a high torque state during processing, which makes it difficult to perform processing. Becomes unstable.

The EVOH used in the present invention contains a small amount of modifying components such as unsaturated carboxylic acid, its anhydride,
Any modified polymerization component such as salts, esters, α-olefins, vinyl ethers, nitrites and amides may be contained.

Examples of the polyolefin resin (B) used in the present invention include ultra-low density polyethylene, (linear) low density polyethylene, high density polyethylene, polypropylene and other polyolefins, ethylene-vinyl acetate copolymer having a high ethylene content. Examples thereof include copolymers and copolymers mainly composed of olefins such as ethylene-ethyl acrylate copolymer, but the present invention is not limited to these examples.

The carboxylic acid-modified polyolefin resin (C) used in the present invention is a polyolefin resin selected from the above (B) copolymerized or graft modified with a carboxylic acid. Examples thereof include maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride.
Among them, maleic anhydride is preferably used. The content of the carboxyl group is practically 0.002-0.2 equivalent, preferably 0.005-0.1 equivalent per 100 g of the carboxylic acid-modified polyolefin resin (C).

The mixing ratio of each component in the present invention is
The mixing ratio of (A) EVOH and (B) polyolefin resin and (C) carboxylic acid modified polyolefin resin is (A) / [(A) + (B) + (C)] = 0.4 to 0.9.
(Weight ratio), preferably in the range of 0.5 to 0.8 (weight ratio).

If the mixing ratio is smaller than the above range, the effect of improving impact resistance, flex crack resistance, stretchability and thermoformability becomes insufficient, and if it exceeds the above range, EVOH is used. The stable matrix formation of No. 1 becomes unstable, matrix inversion easily occurs, and stable physical properties cannot be obtained.

Further, in the above, the ratio of (B) to (C) is such that the equivalent number of carbonyl groups in [(B) + (C)] is relative to 100 g of the resin [(B) + (C)]. 0.002-
It is necessary to be 0.05, preferably 0.004 to 0.02, and more preferably 0.004 to 0.01. When the number of equivalents of the carbonyl group is smaller than the above range, the compatibility between EVOH and the polyolefin resin becomes insufficient and the formation and maintenance of a stable EVOH matrix becomes unstable. On the other hand, if the amount exceeds the above range, the surface of the film of the obtained composition is notably roughened and causes a poor appearance, and at the same time, the coloring is intensified and the appearance is unfavorably unsuitable. Further, the resin blend of the present invention may be blended with various additives which are commonly used in thermoplastic resins for molded articles.

Examples of additives include antioxidants, ultraviolet absorbers, plasticizers, antistatic agents, lubricants, colorants, fillers, etc., and these are compounded within the range not impairing the action and effect of the present invention. be able to. Specifically, as the antioxidant, 2,5-di-t-butylhydroquinone, 2,6-di-
t-butyl-p-cresol, 4,4'-thiobis- (6
-T-butylphenol, 2,2'methylene-bis (4-
Methyl-6-t-butylphenol, tetrakis- [methylene-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, octadecyl-3- (3', 5-di- t-Butyl-4'-hydroxyphenyl) propionate, 4,4'-thiobis- (6-t
-Butylphenol) and the like.

As the UV absorber, ethyl-2-cyano-3,3-diphenylacrylate, 2- (2'-hydroxy-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'hydroxy-3) is used. '-T-butyl-
5'-methylphenyl) -5-chlorobenzotriazole, 2-hydroxy-4-methoxybenzophenone,
2,2'-dihydroxy-4-methoxybenzophenone,
2-Hydroxy-4-octoxybenzophenone and the like can be mentioned. As the plasticizer, dimethyl phthalate, diethyl phthalate, dioctyl phthalate, wax, liquid paraffin, phosphoric acid ester and the like can be mentioned, and as the antistatic agent, penta Erislit monostearate, sorbitan monopalmitate, sulfated oleic acid, polyethylene oxide, carbowax and the like, lubricants such as ethylenebisstearylamide, butyl stearate, calcium stearate, zinc stearate, etc., as a colorant Include carbon black, phthalocyanine, quinacridone, indoline, azo pigments, titanium oxide, red iron oxide, and the like, and as the filler, glass fiber, mica, ballastonite, and the like are used.

Also, various other thermoplastic resins may be blended in appropriate amounts, and such other thermoplastic resins include
Polyolefins other than (B) or modified polyolefins obtained by graft-modifying these with unsaturated carboxylic acids or their derivatives, polyamides, polyesters, polystyrenes, polyacrylonitriles, polyurethanes, polyacetals, polycarbonates, melt-moldable polyvinyl alcohol resins, and the like. . The addition method and timing of the various additives described above are not particularly limited as long as they do not impair the effects of the present invention. The method for producing the resin composition of the present invention is as follows. As a method for mixing the respective components of the present invention, a generally known mixer such as a twin-screw extruder can be used and is not particularly limited.

As a concrete manufacturing method of the present invention,
A mixed melt or solid of (B) and (C) is prepared in advance, and then melt (A) and melt [(B) + (C)], melt (A) and solid [(( B) + (C)], or a method of mixing and melting the solid matter (A) and the solid matter [(B) + (C)], and the like, but not particularly limited, as a more specific method of the present invention. , A melt side feed method, a solid side feed method, a dry blend method and the like.
The melt side feed method is a method in which one of the resin composition components is placed in a molten state and the other components are melt-mixed in the molten state. For example, (B) and (C) are mixed by a twin-screw extruder. After being heated and melted at a melting temperature of about 180 to 280 ° C., a melting temperature of 15 from the side supply port of the twin screw extruder.
A method of supplying (A) heated and melted at about 0 to 300 ° C. and kneading so as to obtain a uniform composition can be mentioned.

This method is particularly useful when the difference in melt viscosity between (A) and [(B) + (C)] is large. The solid side feed method is a method in which a component (A) having a high melting point in a resin composition component is put in a molten state, and a component [(B) + (C)] having a low melting point is added thereto in a solid state, followed by melt mixing. Method, for example, (A) is heated and melted at a melting temperature of about 180 to 280 ° C. by a twin-screw extruder, and then dry blended from a side supply port of the twin-screw extruder (B).
And (C) are supplied by a quantitative feeder and kneaded so as to form a uniform composition in the extruder.
In addition, the dry blending method uses the solid material of (A) and [(B) +
(C)] and the solid matter are collectively supplied to a twin-screw extruder and kneaded.

In the present invention, in the above method, when the screw length of the extruder is L (mm) and the diameter is D (mm), [(B) + (C) premixed with (A) is used. )]
The specific energy (E ₁ ) at the time of extrusion per L / D unit when melt-mixing and is 0.020 kW · hr / kg or less,
It is necessary to perform extrusion processing at preferably 0.018 kW · hr / kg or less, and more preferably 0.015 kW · hr / kg or less. This specific energy is 0.020k
When W · hr / kg is exceeded, gel is frequently generated during molding and unstable physical properties are not preferable. or,
In the present invention, when [(B) + (C)] is melt-mixed in advance with an extruder, the specific energy (E ₂ ) at the time of extrusion per L / D unit is larger than the above (E ₁ ). The case is preferable, and the effect of the present invention is further exhibited.

Here, the specific energy means the energy given to the resin per unit discharge amount (1 kg) from the kneading equipment for the effect of kneading when the resin is melt-kneaded, and generally has a small numerical value. In this case, the kneading effect is low. That is, an electric current meter, a voltmeter, etc. are attached to the motor of the extruder, the electric power consumption of the motor is obtained from this, and this is multiplied by the power factor of the motor (usually about 0.85) to obtain the electric energy per discharge amount. It is defined by calculation, and the specific energy for the resin is obtained by the difference between the specific energy during resin extrusion and the specific energy during idle operation.

In this way, (A), (B), (C)
To obtain a resin composition by melt-kneading peculiar to the present invention, and by further manufacturing the resin composition into a resin molded product such as pellets, films and sheets, impact resistance, flex fatigue resistance, gelation prevention property, etc. It is possible to obtain an excellent resin molded product. Often, these crushed products (such as when reusing recovered products) or pellets are subjected to melt molding again, and even when the pellets or the like are remelt molded, the effect of the present invention is not impaired and excellent. Shows impact resistance, flex fatigue resistance, gelation resistance, etc.

As the melt molding method, extrusion molding (T-die extrusion, inflation extrusion, blow molding, melt spinning, profile extrusion, etc.) is mainly adopted. The melt molding temperature is often selected from the range of 170 to 270 ° C. It is possible to obtain a molded product having good dimensional accuracy, including the injection blow molding method. It is also possible to use two or more kinds of EVOH having different ethylene contents and saponification degrees in combination during melt molding. In the melt molding, in addition to the above-mentioned various additives, as a stabilizer, a surfactant, a crosslinkable substance (epoxy compound, polyvalent metal salt, inorganic or organic polybasic acid or its salt, etc.), a reinforcing material Fibers (glass fiber, carbon fiber, etc.), hydrotalcite, etc. can be blended in appropriate amounts.

The resin composition of the present invention is a laminated structure having at least one molded article such as the film or sheet of the present invention, in addition to the production of a resin molded article having only the resin composition as a single layer as described above. Is often put to practical use. In the production of the laminated structure, a film obtained from the resin composition of the present invention, one or both sides of the layer of a resin molded product such as a sheet is laminated with another substrate,
As a laminating method, for example, a method in which a thermoplastic resin is melt-extruded into the molded product (film, sheet, etc.), or conversely, the composition or molded product (pellet etc.) is melt-extruded in a substrate such as a thermoplastic resin Method, a method of co-extruding the composition or molded product with another thermoplastic resin, further, the resin molded product obtained in the present invention and a film of another substrate, a sheet, an organic titanium compound, an isocyanate compound, Examples include a method of laminating using a known adhesive such as a polyester compound.

In the case of coextrusion, the other resin is linear low density polyethylene, low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, ionomer, ethylene-propylene copolymer, ethylene. -Acrylic ester copolymer, polypropylene, propylene-α-olefin (having 4 to 20 carbon atoms)
.Alpha.-olefin) copolymers, homo- or copolymers of olefins such as polybutene and polypentene, or polyolefins in a broad sense such as those obtained by graft-modifying homo- or copolymers of these olefins with unsaturated carboxylic acids or their esters. Resin, polyester, polyamide, copolyamide, polyvinyl chloride, polyvinylidene chloride, acrylic resin, styrene resin, vinyl ester resin,
Examples thereof include polyester elastomer, polyurethane elastomer, chlorinated polyethylene, chlorinated polypropylene and the like. Saponified ethylene-vinyl acetate copolymers can also be coextruded.

Further, when the resin molded product such as the film or sheet obtained by the present invention is extrusion-coated with another substrate, or when the film or sheet of another substrate is laminated with an adhesive, In addition to the thermoplastic resin of
Metal foil, uniaxially or biaxially stretched plastic film or sheet, woven cloth, non-woven cloth, metallic cotton strip, wood surface, etc.) can be used. As for the layer structure of the laminated structure, a layer of the composition obtained by the present invention is A (A ₁ , A ₂ ...) And another substrate, for example, a thermoplastic resin layer is B (B ₁ , B ₂ . ...),
If it is a film, a sheet, or a bottle, not only a two-layer structure of A / B, but also B / A / B, A / B / A, A ₁ / A ₂ /
Any combination such as B, A / B ₁ / B ₂ , B ₂ / B ₁ / A / B ₁ / B ₂ is possible, and in the filament form, A, B
Any combination such as a bimetal type, a core (A) -sheath (B) type, a core (B) -sheath (A) type, or an eccentric core-sheath type is possible.

In the case of coextrusion, A may be blended with B and B may be blended with A, or at least one of A and B may be blended with a resin for improving the adhesiveness of both layers. The laminated structure may have any shape, and examples thereof include a film, a sheet, a tape, a bottle, a pipe, a filament, and a modified cross-section extrudate. Further, the obtained laminated structure is subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry laminating treatment, solution or melt coating treatment, bag making processing, deep drawing processing, box processing, tube processing, split processing, etc., if necessary. It can be performed. Further, the above-mentioned molded product or laminated structure can be stretched as necessary to improve its physical properties.

That is, the resin composition obtained in the present invention is melt-molded to produce a raw film. The thickness of the film is not particularly limited and can be set to several μ to several 100 μ. The film referred to in the present invention is a sheet,
It means a film in a broad sense including forms such as tapes, tubes, and containers. Since such a film has a uniform film thickness, it has an extremely high product value. Further, such stability of the film thickness is maintained even if the molding process is continued for a long time. The film obtained as described above may be subjected to moisture conditioning treatment such as moisture absorption or drying, if necessary, and then subjected to stretching.

The stretching may be either uniaxial stretching or biaxial stretching, and it is preferable to perform stretching with as high a ratio as possible in terms of physical properties. In the case of uniaxial stretching, it is preferably 1.5 times or more, particularly preferably 2 times or more. In the case of biaxial stretching, the area magnification is preferably 1.5 times or more, particularly preferably 2 times or more, further preferably 4 times or more. As a stretching method, a roll stretching method,
In addition to the tenter stretching method, the tubular stretching method, the stretching blow method and the like, deep drawing, vacuum forming and the like having a high stretching ratio can be adopted. In the case of biaxial stretching, simultaneous biaxial stretching method,
Any of the sequential biaxial stretching methods can be adopted. The stretching temperature is selected from the range of about 40 to 150 ° C. After the stretching is completed in this way, heat setting is then performed. The heat setting can be carried out by a well-known means, and while maintaining the stretched film in a tension state, it is 50 to 160 ° C., preferably 80 to 16 ° C.
Heat treatment is performed at 0 ° C. for about 2 to 600 seconds.

If necessary, the stretched film obtained is
Cooling treatment, rolling treatment, printing treatment, dry laminating treatment, solution or melt coating treatment, bag making processing, deep drawing processing, box processing, tube processing, split processing and the like can be performed. The film, sheet or container obtained as described above is useful as various packaging materials for foods, pharmaceuticals, industrial chemicals, agricultural chemicals and the like.

Particularly, in the present invention, the resin composition of the present invention is used as an intermediate layer, and adhesive layers are provided on both sides of the intermediate layer,
Furthermore, it is preferably used for an inner container for a back-in-box in which a surface layer is provided on the outside of the adhesive layer. The inner container for the back-in box has at least a surface layer / adhesive layer / intermediate layer /
It consists of a five-layer laminate of an adhesive layer / surface layer, and the surface layer is preferably an ethylene-α-olefin copolymer having a density of 0.86 to 0.95 g / cm ³ (20 ° C.). The density referred to here is a value measured by JIS K 6760 at 20 ° C. When the density is lower than the above range, mechanical properties of the laminate are insufficient and blocking occurs. On the contrary, when it is large, the bending fatigue resistance becomes insufficient, which is not preferable. Further, ethylene-α-olefin means ethylene and butene-1, pentene-1,
4-methylpentene-1, hexene-1, octene-1
Is a copolymer having 18 or less carbon atoms. Among these, ethylene-α using an α-olefin having 4 to 8 carbon atoms
-Olefin copolymers are preferably used.

Further, as the adhesive resin used in the adhesive layer, a density of 0.86 to 0.95 g / cm ³ modified with an unsaturated carboxylic acid or an anhydride thereof (measurement conditions are for the above surface layer). The same) as the ethylene-α-olefin copolymer are preferable and can be obtained by copolymerizing or graft-modifying the same resin as described in the above surface layer with an unsaturated carboxylic acid or an anhydride thereof. Of course, the modification also includes a blend of an unmodified ethylene-α-olefin copolymer and an unsaturated carboxylic acid or an anhydride thereof. As the unsaturated carboxylic acid or its anhydride, maleic acid,
Examples thereof include maleic anhydride, fumaric acid, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, citraconic acid, hexahydrophthalic anhydride and the like, among which maleic anhydride is preferably used.

At this time, the amount of the unsaturated carboxylic acid or its anhydride contained in the ethylene-α-olefin copolymer is preferably 0.01 to 10% by weight, more preferably 0.1 to 3% by weight. is there. If the content in the modified products is small, the adhesive strength with the intermediate layer and the surface layer will be reduced, and conversely, if the content is large, a crosslinking reaction will occur and moldability will deteriorate, which is not preferable. or,
The thickness of each layer of the laminate of the surface layer / adhesive layer / intermediate layer / adhesive layer / surface layer of the present invention is 10 to 600 μ / 2.
Is selected from the range of 50 μ / 1 to 50 μ / 2 to 50 μ / 10 to 600 μ, and preferably 30 to 200 μ / 5.
10 μ / 5 to 30 μ / 5 to 10 μ / 30 to 200 μ.

The present invention is characterized in that a specific EVOH / polyolefin resin melt-mixed composition is used for the intermediate layer. The laminate of the present invention using EVOH for the intermediate layer is a surface layer / adhesive layer. / Intermediate layer / Adhesive layer / Surface layer, not only the surface layer / adhesive layer / intermediate layer / intermediate layer / adhesive layer / surface layer / adhesion It is also possible to make a laminate of 6 layers or more such as agent layer / surface layer, surface layer / adhesive layer / surface layer / adhesive layer / intermediate layer / adhesive layer / surface layer / adhesive layer / surface layer, etc. is there. Further, using a nylon layer, surface layer / adhesive layer / nylon layer / intermediate layer / adhesive layer / surface layer, surface layer / adhesive layer / nylon layer / intermediate layer / nylon layer / adhesive layer / surface layer , Surface layer /
Adhesive layer / Nylon layer / Adhesive layer / Intermediate layer / Adhesive layer /
It is also possible to use a laminate such as a surface layer, and the resin for the nylon layer used at this time includes nylon 6, nylon 6-66, nylon 12, amorphous nylon, or a blend thereof.

The inner container for the back-in-box of the present invention is
It can be manufactured mainly by a heat sealing method and a blow molding method. In the heat-sealing method, the film for the intermediate layer and the surface layer formed by the inflation method or the flat film method is dry-laminated through an adhesive layer, or a laminate in which each layer is laminated by a co-extrusion method or the like. Body, as it is, or if necessary, 2 or 3
A hole for attaching the sealing plug of the liquid injection port is punched out by superposing on the seed, and the sealing plug of the liquid injection port which has been previously formed by injection molding is fused to the hole by the heat sealing method. At that time, the laminated body and another laminated body which has not been punched are combined and heat-sealed in four directions to form an inner container for a back-in-box.

In the blow molding method, the cylindrical laminated body extruded from the extruder is clamped with a mold to form it.
The sealing plug of the liquid injection port, which has been molded by injection molding in advance, is set in the mold and is fused with the molding container during blow molding. Then open the liquid inlet. The thus-obtained inner container for a back-in-box of the present invention is excellent in crack resistance and bending fatigue resistance, and also has excellent gas barrier properties and impact resistance.

The present invention is also suitably used for a buffer material (air cap) having a projecting hollow chamber containing at least one layer of the above-mentioned resin composition of the present invention. The buffer material may be produced in various layer configurations without particular limitation, in addition to a single layer, but preferred examples include, for example, a polyolefin resin for both surface layers and a resin composition of the present invention for the intermediate layer. , An adhesive layer is provided between both surface layers and the intermediate layer 5
It is manufactured using a layer film.

Examples of the polyolefin resin include homopolymers or copolymers of olefins such as polyethylene, polypropylene, ethylene-α-olefins and ethylene-vinyl acetate copolymers, as well as acrylic acid and maleic anhydride. Examples thereof include modified polyolefin resins graft-polymerized with polyolefins. Examples of the resin used as the adhesive layer include the adhesive resin used in the above-mentioned inner container for back-in-box. Further, the cushioning material has a projecting hollow chamber, and in order to provide the hollow chamber, for example, an embossed film and a non-embossed film are heat-sealed. The embossing can be performed by a conventionally known method without any particular limitation.

The cushioning material having the protruding hollow chambers thus obtained is excellent in bending fatigue resistance, impact resistance and workability, and
Since the gas barrier property is high even when a load is applied,
It is difficult for air to escape from the independent hollow chamber, retains excellent cushioning properties for a long period of time, and is useful in various fields including the packaging field.

[0045]

[Working] The present invention, when a mixture of (A) EVOH, (B) polyolefin resin and (C) carboxylic acid-modified polyolefin resin is melt-kneaded in an extruder, the L / D unit of the extruder is used. Since the specific energy (E ₁ ) during extrusion per hit is lower than before, impact resistance, bending fatigue resistance,
EV showing excellent effect with no variation in gelation prevention property
An OH / polyolefin resin composition can be obtained. Furthermore, the resin composition of the present invention is very useful in various fields including the packing field of an inner container for a back-in-box or a cushioning material having a hollow chamber.

[0046]

EXAMPLES The present invention will be specifically described below with reference to examples. In the examples, "parts" and "%" mean weight basis. Example 1 EVOH (A) [Ethylene content 30 mol%, melt index 8 g / 10 min (210 ° C., load 2160 g),
Degree of saponification 99.5 mol%] was fed to the twin-screw extruder to
It was heated and melted at 0 ° C. 25 parts of ultra-low density polyethylene (C) previously modified with 1.5% of maleic anhydride, and ultra-low density polyethylene (B) [melt index 1 g / 1
0 minutes (190 ℃, load 2160g), density 0.918g
/ Cm ³ ] 75 parts in a twin-screw extruder with a specific energy (E ₂ ) to the resin of 0.1 per L / D unit.
After being melted by heating to 230 ° C. under the condition of 44 kW · hr / kg, EVOH was supplied from the side supply port of the twin-screw extruder so that the ratio of EVOH to the total resin was 70%, The specific energy (E ₁ ) for resin is 0.012kW · h per L / D unit in the twin-screw extruder
Under conditions of r / kg, both were kneaded so as to be uniform and extruded to produce pellets. At this time, the equivalent number of carbonyl groups in 100 g of [(B) + (C)] was 0.004.

Next, the pellets were fed to a single-screw extruder equipped with a T-die and formed into a film having a thickness of 30 μ. The film forming conditions by the single screw extruder were as follows. Screw inside diameter 40mm L / D 28 T-die coat hanger type die width 45mm extrusion temperature _{C 1 -190 ℃, H -220 ℃} C 2 -210 ℃, D 1 -220 ℃ C 3 -220 ℃, D 2 -220 ℃ C ₄ 0.3 m -230 ° C. the resulting film (thickness 30.mu.) in the longitudinal direction
Five samples were sampled at intervals of A4 size, and bending fatigue resistance, impact resistance, film appearance and oxygen permeability of the sampling film were measured. The measuring method is as shown below.

(Bending Fatigue Resistance) A gelbo flex test was performed 500 times under the conditions of 20 ° C. and 0% RH, and then evaluated by the number of pinholes in the sampling film. The evaluation result is an average when the same test is performed on 5 samples. ○: less than 5 △: less than 5 to 10 ×: 10 or more

(Impact resistance) Impact value (kg · c) measured by a film impact test under the conditions of 20 ° C. and 65% RH.
It was evaluated by m). The evaluation results are shown as an average value and a variation (difference between the maximum value and the minimum value) when the same test was performed on five samples. (Film appearance) Sampling film 10 cm x 10
The number of gels (0.1 mm or more) of the film per cm was visually evaluated. The evaluation result is an average when the same test is performed on 5 samples. ○: less than 5 △: less than 5 to 10 ×: 10 or more (oxygen permeability) 20μ under conditions of 20 ° C and 65% RH
oxygen permeability of m (cc ・ 20μ / m ²・ day ・ at
m) was evaluated. The evaluation result is an average value when the same test is performed on 5 samples.

Examples 2 to 10 and Comparative Example 1 As shown in Table 1, the composition of EVOH (A) used, the amount of (A) blended with all resins, [(B) + (C)] 100 g.
Number of equivalents of carbonyl group in the resin, specific energy (E ₂ ) per L / D unit to resin in melt mixing of (B) and (C), melt mixing of (A) and [(B) + (C)] Specific energy (E) per unit L / D for resin in
Pellets were prepared in the same manner as in Example 1 except that ₁ ) was changed, and a film was prepared from the pellets in the same manner as in Example 1. The flexural fatigue resistance, impact resistance, film appearance and oxygen permeability of each of the obtained films were measured in the same manner as in Example 1.

Comparative Example 2 (A) EVOH, (B) polyolefin resin, and (C) carboxylic acid-modified polyolefin resin used in Example 1 were collectively supplied to a twin-screw extruder, and the temperature was set to 210 to 250 ° C.
A film was produced in the same manner as in Example 1 except that the pellets were produced by melt mixing and extruding. At this time, the biaxial extruder was used so that the specific energy with respect to the resin was 0.012 kW · hr / kg per L / D unit. The flexural fatigue resistance, impact resistance, film appearance and oxygen permeability of each of the obtained films were measured in the same manner as in Example 1. Table 2 shows the evaluation results of Examples and Comparative Examples.
Shown in

[0052]

Table 1 EVOH composition EVOH Carbonyl ratio Energy ratio Energy Et Et Sv MI compounding amount Base equivalent number Gee (E ₂ ) Gee (E ₁ ) Example 1 30 99.8 12 70 0.004 0.44 0.012 〃 2 30 99.8 3 60 0.004 0.50 0.011 〃 3 30 99.8 8 55 55 0.005 0.48 0.011 〃 4 40 99.6 8 60 0.003 0.44 0.013 〃 5 45 99.2 12 70 0.003 0.51 0.011 〃 6 45 99.9 12 60 60 0.005 0.51 0.013 〃 7 30 99.8 2 60 0.004 0.45 0.018 〃 8 40 99.6 8 60 0.004 0.012 0.02 012 〃 9 30 99.8 8 60 0.006 0.70 0.012 〃 10 30 99.8 8 60 0.001 0.45 0.0012 Comparative Example 1 30 99.8 3 60 0.004 0.44 0.040 〃 2 30 99.8 10 70 0.004-0.012

Note) Et: ethylene content (mol%) Sv: degree of saponification (mol%) MI: melt index (g / 10 minutes (210 ° C., load 2160 g)) EVOH blending amount: (A) × 100 / [(A) + (B) +
(C)] (wt%) Carbonyl group equivalent number: [(B) + (C)] number of carbonyl group in 100 g E ₂ : per L / D unit to resin in melt mixing of (B) and (C) Specific energy (kW · hr / kg) E ₁ : specific energy per L / D unit (kW · hr) for the resin in the melt mixing of (A) and [(B) + (C)]
hr / kg) In Comparative Example 2, (A) EVOH, (B) polyolefin resin, and (C) carboxylic acid-modified polyolefin resin were collectively charged.

[0054]

[Table 2] Bending and impact resistance film Oxygen permeability Fatigue (kg / cm) Appearance (cc ・ 20μ / m ²・ day ・ atm) Average value Variation Example 1 ○ 18 1 ○ 0.6 〃 2 ○ 20 1 ○ 0.7 〃 3 ○ 22 1 ○ 0.7 〃 4 ○ 18 3 ○ 2.0 〃 5 ○ 23 3 ○ 4.1 〃 6 ○ 21 1 ○ 5.0 〃 7 ○ 16 3 ○ 0.8 〃 8 △ 16 3 ○ 1.6 〃 9 △ 17 2 △ 5.1 〃 10 △ 15 3 ○ 3.3 Comparative Example 1 ○ 17 11 × 0.9 〃 2 × 11 7 × 3.1 Note) Variation Is obtained by the difference between the maximum value and the minimum value.

Example 11 The same composition as in Example 1 (I-1) was used as the intermediate layer, and MI2.5 g / MI was used for both surface layers, using a coextrusion device of 5 layers of 3 types.
10 minutes (190 ° C, load 2160g), density 0.890
g / cm ³ , ethylene content 90 mol% ethylene-1
-Butene random copolymer LLDPE (II-1), the adhesive layer between the intermediate layer and both surface layers is (II-1) grafted with 0.5% maleic anhydride at MI of 3.0 g / 10. Minute (190 ℃, load 2160g) modified LLDPE (II
I-1) and (II-1) / (III-1) / (I-
1) / (III-1) / (II-1) is 35 μ / 10 μ / 1
A 5-layer coextrusion laminated film having a constitution of 0 μ / 10 μ / 35 μ was obtained under the following coextrusion molding conditions.

[0056]

[0057]

[0058]

Obtained laminated film (500 mm × 70
(0 mm) were piled up, and a hole (diameter 43 mm) for liquid injection was opened by a punching machine. Next, a laminated film having no holes (500 mm × 700 mm, two sheets stacked) was laminated with the above laminated film and heat-sealed on four sides to manufacture an inner container for a back-in-box. At that time, a sealing plug made of high-density polyethylene was attached to the hole for injecting the liquid, and the periphery was heat-sealed and fixed tightly. Next, put the inner container in a cardboard box, and fill it with about 18
A running transportation test of about 2500 km with a liter put was performed. After the test, the state of the laminated film around the sealing stopper of the inner container was visually observed with an SEM (electron microscope, 1000 times). The oxygen permeability (cc /
air * bag * day) was examined under the conditions of 20 [deg.] C. and 65% RH using an oxygen permeability measuring device (OX-TRAN10 / 50) manufactured by Modern Control.

Examples 12 to 16 and Comparative Examples 3 and 4 Using the intermediate layer, adhesive layer and surface layer shown in Table 3, an inner container was prepared and evaluated in the same manner as in Example 11.

[0061]

[Table 3] Laminated composition ¹⁾ Evaluation item Intermediate layer Surface layer Adhesive layer SEM observation Oxygen permeability ²⁾ Example 11 I-1 II-1 III-1 No abnormality 0.40 / 0.40 12 I-2 II-2 III- 2 No abnormality 0.55 / 0.57 13 I-3 II-3 III-3 No abnormality 1.5 / 1.8 14 I-4 II-4 III-1 No abnormality 0.50 / 0.50 15 I-5 II-1 III-1 No abnormality 0.90 / 0.94 16 I-6 II-1 III-1 No abnormality 0.55 / 0.70 Comparative example 3 I-7 II-1 III-1 Crack generation 0.52 / 0.80 4 I-8 II-1 III-1 Crack generation 0.65 /> 200

1) Each constituent resin is as follows. I-1: (I-1) above, I-2: resin similar to Example 3, I-3: resin similar to Example 5, I-4: resin similar to Example 7, I-5 : Resin similar to Example 8, I-6: Resin similar to Example 9, I-7: Resin similar to Comparative Example 1, I
-8: Resin similar to Comparative Example 2

II-1: Ethylene-1-butene random copolymer (MI 2.5 g / 10 minutes, density 0.890, ethylene content 90 mol%), II-2: ethylene-1-butene random copolymer (MI 4.0 g / 10 min, density 0.
872, ethylene content 82 mol%), II-3: ethylene-propylene copolymer (MI 0.8 g / 10 min, density 0.864, ethylene content 80 mol%), II-4: ethylene-4-methyl Penten-1 (MI 2.0g / 10
Min, density 0.920, ethylene content 97 mol%)

III-1: 0.5% maleic anhydride grafted onto B-1 above. III-2: 2.5% maleic anhydride grafted on II-2 above, 10 times II-
A blend of 90 parts of 1. III-3: The above II-3 is grafted with 3% of maleic anhydride. 2) The oxygen permeability is represented by the value before and after the test.

Example 17 A 5-layer coextrusion laminated film having the same constitution as that of Example 11 was obtained under the following coextrusion molding conditions using a coextrusion device of 5 layers of 3 types.

[0066]

[0067]

The obtained laminated film (500 mm × 70
(0 mm) surface is embossed, and the embossed film and the above laminated film (non-embossed film) are laminated and adhered (heat-sealed at 90 ° C.) to obtain a laminated cushioning material having a protruding hollow chamber. Manufactured.
The width of the protrusion (embossed portion) is 10 mm, the height of the protrusion is 4 mm, and the distance between the protrusions is 10 mm. The oxygen permeability of the laminated film and the creep test of the laminated cushioning material were evaluated by the following methods.

(Oxygen permeability) After performing a Gelbo flex test 500 times under the conditions of 20 ° C. and 0% RH, 2
Oxygen permeability (c of 20 μm at 0 ° C. and 65% RH)
c · 20 μ / m ² · day · atm) was evaluated.

(Creep test) After conducting a Gelbo flex test 500 times under the conditions of 20 ° C. and 0% RH,
The laminated cushioning material was cut into 100 mm square pieces, several sheets were superposed, a load of 2 kgf was applied from above, the height was set to 100 mm, and the height reduction rate (%) after 15 days was calculated. The measurement conditions are 20 ° C. and 65% RH.

Examples 18 to 22, Comparative Examples 5 and 6 Using the intermediate layer, adhesive layer and surface layer shown in Table 4, a laminated cushioning material was prepared and evaluated in the same manner as in Example 17.
In Examples 21 and 22, heat sealing was performed at 140 ° C.

[0072]

[Table 4] Laminated structure ¹⁾ Evaluation item Intermediate layer Surface layer Adhesive layer Oxygen permeability Creep test Example 17 I-1 II-1 III-1 0.6 <1 18 I-2 II-2 III-20 .7 <1 19 I-3 II-3 III-3 4.1 2 20 I-4 II-4 III-1 0.8 <1 21 I-5--1.6 1 22 I- 6--5 .1 5 Comparative Example 5 I-7 II-1 III-1 21 15 6 I-8 II-1 III-1 25 23

1) Each constituent resin I-1, I-2, I-3, I-
4, I-5, I-6, I-7, I-8, II-1, II-2, II
-3, II-4, III-1, III-2, III-3 are shown in Table 3 above.
The same as that used in. In addition, Examples 21 and 22 were evaluated as a single layer instead of 3 layers of 5 layers.

[0074]

INDUSTRIAL APPLICABILITY The present invention provides a resin composition capable of producing a molded product having stable physical properties, which is extremely excellent in bending fatigue resistance, impact resistance, gelation resistance, gas barrier property and the like. It can be obtained, and in particular, it can be suitably used for an inner container for a back-in-box, a cushioning material having a protruding hollow chamber, and the like.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] December 25, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

If the mixing ratio is smaller than the above range, the effect of improving impact resistance, flex crack resistance, stretchability and thermoformability becomes insufficient, and if it exceeds the above range, EVOH is used. Stable matri
The formation of the matrix becomes unstable, matrix inversion easily occurs, and stable physical properties cannot be obtained.

Claims (9)

[Claims] 1. A saponified ethylene-vinyl acetate copolymer having an ethylene content of 20 to 60 mol% and a saponification degree of 90 mol% or more, (B) a polyolefin resin,
(C) A carboxylic acid-modified polyolefin resin,
In melt-mixing (A) and premixed [(B) + (C)] with an extruder, the screw length of the extruder is L (mm), and the diameter is D (mm). If you do, L
The specific energy (E ₁ ) at the time of extrusion per D / D unit is 0.
A resin composition obtained by extrusion processing at 020 kW · hr / kg or less. 2. A premixed [(B) + with (A).
(C)] is melt-mixed with an extruder, L / D
Specific energy (E ₁ ) at the time of extrusion per unit is 0.01
The resin composition according to claim 1, wherein the resin composition is extruded at 8 kW · hr / kg or less. 3. When melt-mixing [(B) + (C)] in advance with an extruder, the screw length of the extruder is set to L.
(Mm) and the diameter is D (mm), the specific energy (E ₂ ) at the time of extrusion per L / D unit is (A),
3. The specific energy (E ₁ ) at the time of extrusion per L / D unit when melt-mixing with [(B) + (C)] mixed in advance is larger than that. Resin composition. 4. (A) / [(A) + (B) + (C)] is 0.4 to 0.9 (weight ratio), and [(B) + (C)]
The equivalent number of carbonyl groups in 100 g is 0.002 to 0.
It is 05, The resin composition of Claim 1, 2 or 3 characterized by the above-mentioned. 5. (A) / [(A) + (B) + (C)] is 0.5 to 0.8 (weight ratio), and [(B) + (C)]
The equivalent number of carbonyl groups in 100 g is 0.002 to 0.
It is 05, The resin composition in any one of Claims 1-4 characterized by the above-mentioned. 6. The resin composition according to claim 1 as an intermediate layer, and an adhesive layer provided on both sides of the intermediate layer,
An inner container for a back-in-box, further comprising a surface layer provided outside the adhesive layer. 7. The surface layer has a density of 0.86 to 0.95 g / c.
The inner container for a back-in-box according to claim 6, which is composed of an ethylene-α-olefin copolymer of m ³ (20 ° C.). 8. The density of the adhesive layer modified with an unsaturated carboxylic acid or an anhydride thereof, 0.86 to 0.95 g / cm.sup.2.
^The inner container for a back-in-box according to claim 6, comprising an ethylene-α-olefin copolymer of ³ (20 ° C). 9. A cushioning material having a hollow chamber, comprising at least one layer of the resin composition according to any one of claims 1 to 5.