JP2018058943A - Resin composition, and multilayered structure and liquid container prepared therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition that makes it possible to obtain an inner container having excellent gas barrier properties and excellent film strength while having a high level of flexibility.SOLUTION: A resin composition contains an ethylene-vinyl ester copolymer saponified product (A), an ethylene-α-olefin copolymer (B) (excluding (C) component), a carboxyl group-containing ethylene-α-olefin copolymer (C) and an ionomer (D).SELECTED DRAWING: None

Description

  The present invention relates to a resin composition containing a saponified ethylene-vinyl ester copolymer (hereinafter sometimes abbreviated as EVOH), a multilayer structure using the same, and a liquid container.

  In recent years, due to the advantages of convenience, light weight, and drop resistance, a flexible plastic inner container with a liquid inlet inside a cardboard box for transporting and storing beverage liquids such as mineral water and wine ( A bag-in-box containing a bag-in-box inner container) is used.

In order to maintain the freshness and quality of the contents as these inner containers, bags having gas barrier properties are required. However, when the bag has a metal laminate layer, the flexibility tends to be insufficient, and when the bag is a metal vapor-deposited bag, pinholes are likely to occur, and the gas barrier property tends to be lowered. Therefore, a multilayer structure having an EVOH layer that exhibits a gas barrier property against oxygen or the like and is excellent in melt moldability is used.
An EVOH film is rigid because it has high crystallinity, and a pinhole is likely to be generated by bending. Therefore, a resin composition containing a soft component and a compatibilizing agent has been proposed.

  For example, Patent Document 1 includes a saponified ethylene-vinyl ester copolymer having an ethylene content of 20 to 60 mol% and an aliphatic hydrocarbon monomer unit containing a carbon-carbon double bond, and a load of 2160 g at 230 ° C. The polymer has an aliphatic hydrocarbon monomer unit containing a carbon-carbon double bond formed by modifying a polymer having a melt flow rate of 0.01 to 200 g / 10 min under conditions and a polar group-containing compound, at 230 ° C. A polymer having a melt flow rate of 0.01 to 200 g / 10 min under a load of 2160 g, and a hydrocarbon resin having a number average molecular weight of 100 to 3000 and a softening point of 60 ° C. or more and less than 170 ° C. A bag for a bag-in-box comprising a multilayer structure using the contained EVOH resin composition is described.

  Patent Document 2 discloses an ethylene-vinyl alcohol copolymer (A), an unmodified ethylene-α-olefin copolymer (B), an acid-modified ethylene-α-olefin copolymer (C), and an alkali metal salt (D An ethylene-vinyl alcohol copolymer (A), an unmodified ethylene-α-olefin copolymer (B), and an acid-modified ethylene-α-olefin copolymer (C). The total mass ratio [(A) / ((B) + (C))] is 80/20 to 65/35, and the unmodified ethylene-α-olefin copolymer (B) and acid-modified ethylene- The mass ratio [(B) / (C)] of the α-olefin copolymer (C) is 92/8 to 70/30, and the melt flow rate (MFR) of the ethylene-vinyl alcohol copolymer (A) ( 210 ° C. under 2160 g load) is 8.0 / 10 minutes or more and 15 g / 10 minutes or less, and the content of alkali metal salt (D) is ethylene-vinyl alcohol copolymer (A), unmodified ethylene-α-olefin copolymer (B), and acid-modified. It is 25 ppm or more and 300 ppm or less in terms of metal based on the total amount of the ethylene-α-olefin copolymer (C), and the MFR (210 ° C., 2160 g under load) of the resin composition is 2.0 g / 10 min or more 4 A container in a bag-in-box composed of a multilayer structure using a resin composition of 0.0 g / 10 min or less is described.

  Also, in recent years, a film-type non-return pouring with a self-sealing non-return function that automatically prevents the outside air from entering the bag body, which is composed of two laminated soft plastic laminated films on the front and back. A flexible, non-self-supporting liquid-filled packaging body in which a flexible packaging bag provided with a nozzle (liquid pouring nozzle) is filled with liquid materials such as beverages, liquid seasonings, cosmetics, and medicines, and the like There is known a liquid-filled packaging structure comprising an outer container made of hard plastic or paper for storing and holding a container (see, for example, Patent Document 3).

  Furthermore, an outer layer and an inner layer, wherein the inner layer is peeled from the outer layer and shrinks as the contents are reduced, the inner layer includes an EVOH layer made of EVOH, and the EVOH is ethylene A laminate peeling container having a content of 32 mol% or less and a flexural modulus of 2350 MPa or less is known (for example, see Patent Document 4).

International Publication No. 2010/137659 International Publication No. 2015/141610 JP 2011-219115 A JP-A-2015-127246

  In recent years, with the diversification of the shape and design of storefront display packages, inner containers having higher flexibility are required as inner containers of the bag-in-box, the liquid-filled packaging structure, and the delamination container. . However, when the amount of the softening component and / or the compatibilizing agent is increased for the purpose of enhancing the flexibility of EVOH, there is a problem that the gas barrier performance and the film strength are lowered. Then, this invention aims at provision of the resin composition which can obtain the inner container excellent in gas barrier property and film intensity | strength, having a high level of softness | flexibility.

  As a result of diligent research to solve the above problems, the present inventors have found EVOH, an ethylene-α-olefin copolymer (excluding a carboxyl group-containing ethylene-α-olefin copolymer), a carboxyl group. It discovered that the said objective was achieved by mix | blending an ionomer with the resin composition which has a containing ethylene-alpha-olefin copolymer.

That is, the gist of the present invention is that the saponified ethylene-vinyl ester copolymer (A), the ethylene-α-olefin copolymer (B) (excluding the component (C)) (hereinafter referred to as such ethylene-α- Olefin copolymer (B) (excluding component (C)) may be simply referred to as “ethylene-α-olefin copolymer (B)”), carboxyl group-containing ethylene-α-. The resin composition is characterized by containing an olefin copolymer (C) and an ionomer (D).
The present invention also provides a multilayer structure including at least one layer composed of the resin composition. Furthermore, the present invention also provides a liquid container comprising the multilayer structure.

  The resin composition of the present invention has an effect of being excellent in gas barrier properties and film strength while having a high level of flexibility. In general, when the amount of a softening component and / or a compatibilizing agent is increased for the purpose of enhancing the flexibility of EVOH, gas barrier performance and film strength are lowered. When an ionomer is added, EVOH (A) and ethylene-α- It does not inhibit the reaction with the olefin copolymer (B), but rather between EVOH (A), the ethylene-α-olefin copolymer (B) and the carboxyl group-containing ethylene-α-olefin copolymer (C). It is presumed that it acts as an ionic cross-linking part on the interaction. As a result, the gas barrier performance and the film strength are not unexpectedly lowered, and an excellent effect can be obtained.

Hereinafter, although it demonstrates in detail about the structure of this invention, these show an example of a desirable embodiment.
First, each component used in the resin composition of the present invention will be described.

<Description of Saponified Ethylene-Vinyl Ester Copolymer (A)>
EVOH used in the present invention is a water-insoluble resin, and is obtained by saponifying a copolymer of ethylene and a vinyl ester monomer. The ethylene-vinyl ester copolymer is produced by any known polymerization method, for example, solution polymerization, suspension polymerization, emulsion polymerization, etc., and the saponification of the ethylene-vinyl ester copolymer can also be performed by a known method.

  As the vinyl ester monomer, vinyl acetate is typically used from the viewpoint of market availability and good impurity treatment efficiency during production. Other examples include aliphatic vinyl esters such as vinyl formate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl versatate, and benzoic acid. Examples thereof include aromatic vinyl esters such as vinyl acid, and are usually aliphatic vinyl esters having 3 to 20 carbon atoms, preferably 4 to 10 carbon atoms, and particularly preferably 4 to 7 carbon atoms. These are usually used alone, but may be used as a mixture of two or more if necessary.

  The ethylene content of EVOH used in the present invention is that the content of ethylene structural units measured based on ISO 14663 is 20 to 60 mol%. And preferably it is 25-55 mol%, More preferably, it is 35-50 mol%, Most preferably, it is 38-48 mol%. When there is too little content of an ethylene structural unit, it exists in the tendency for the softness | flexibility of a film to fall. On the other hand, when the content of the ethylene structural unit is too high, the gas barrier property tends to be insufficient.

  The saponification degree of the vinyl ester component is a value measured based on JIS K6726 (however, EVOH resin is a solution uniformly dissolved in water / methanol solvent), and is usually 95 mol% or more, more preferably. Is 95 to 100 mol%, more preferably 98 to 100 mol%. This is because as the saponification degree decreases, the gas barrier property tends to decrease.

  Furthermore, in the melt flow rate (MFR) of EVOH, it is usually 0.1 to 100 g / 10 minutes, preferably 0.5 to 50 g / 10 minutes, particularly preferably at 210 ° C. and a load of 2160 g. 1-20 g / 10 min. If the MFR value is too small, the torque tends to be too high during extrusion molding, or vertical streaks tend to occur in the resulting film. On the other hand, if the MFR value is too large, the extrusion moldability becomes unstable. Or the film thickness of the resulting film tends to vary.

As the EVOH used in the present invention, two or more kinds different in ethylene content, saponification degree, and MFR may be mixed and used as long as the EVOH satisfies the above requirements.
Further, as EVOH used in the present invention, a small amount of propylene, isobutene, α-octene, α-dodecene, α-olefins such as α-octadecene, 3-buten-1-ol, 4- 3,4-diacetoxy-1-butene, 2,3-diacetoxy-1-allyl, which are hydroxy group-containing α-olefins such as penten-1-ol and 3-butene-1,2-diol and esterified products thereof Oxypropane, 2-acetoxy-1-allyloxy-3-hydroxypropane, 3-acetoxy-1-allyloxy-2-hydroxypropane, 1,3-diacetoxy-2-methylenepropane, 1,3-dipropionyloxy-2- Hydroxymethylvinylidenediases such as methylenepropane and 1,3-dibutyronyloxy-2-methylenepropane Tate, glycerin monoallyl ether, glycerin monovinyl ether, glycerin monounsaturated alkyl ethers such as glycerin monoisopropenyl ether, unsaturated carboxylic acid or salt / partial alkyl ester / complete alkyl ester / nitrile / amide / anhydride, Copolymers of unsaturated sulfonic acids or salts thereof, vinyl silane compounds, vinyl chloride, styrene and the like may be used. Furthermore, it may be “post-modified” such as urethanization, acetalization, cyanoethylation, oxyalkyleneation, and epoxidation.
In particular, EVOH copolymerized with hydroxy group-containing α-olefins is preferable in terms of good moldability and stretchability.

  In the EVOH used in the present invention, a compounding agent generally blended in advance with EVOH in a range not inhibiting the effect of the present invention, such as a heat stabilizer, an antioxidant, an antistatic agent, a colorant, an ultraviolet absorber, a lubricant. , Plasticizer, light stabilizer, surfactant, antibacterial agent, drying agent, antiblocking agent, flame retardant, crosslinking agent, curing agent, foaming agent, crystal nucleating agent, antifogging agent, biodegradation additive, silane cup A ring agent, an oxygen absorber, etc. may be contained.

  The heat stabilizer is an organic acid such as acetic acid, propionic acid, butyric acid, lauric acid, stearic acid, oleic acid, behenic acid, or an alkali thereof for the purpose of improving various physical properties such as heat stability during melt molding. A salt such as an earth metal salt (sodium, potassium, etc.), an alkaline earth metal salt (calcium, magnesium, etc.), a metal salt (zinc, copper, etc.) belonging to the fourth block d of the periodic table; or sulfuric acid, sulfurous acid Inorganic acids such as carbonic acid, phosphoric acid and boric acid, or alkaline earth metal salts thereof (sodium, potassium, etc.), alkaline earth metal salts (calcium, magnesium, etc.), belonging to the 4th period d block of the periodic table Additives such as salts such as metal salts (zinc, copper, etc.) may be added. Among these, it is particularly preferable to add boron compounds, acetates, and phosphates including acetic acid, phosphoric acid, boric acid and salts thereof.

  When acetic acid is added, the amount added is usually 0.001 to 1 part by weight, preferably 0.005 to 0.2 part by weight, particularly preferably 0.01 to 0.1 part by weight based on 100 parts by weight of EVOH. It is. If the amount of acetic acid added is too small, the effect of acetic acid content tends not to be sufficiently obtained, and conversely if too large, it tends to be difficult to obtain a film having a uniform thickness and appearance.

  When phosphoric acid is added, the amount added is usually 0.0005 to 0.1 parts by weight with respect to 100 parts by weight of EVOH (analyzed by thermal decomposition with sulfuric acid and nitric acid and analyzing phosphate groups by atomic absorption method), preferably 0.001 to 0.05 part by weight, particularly preferably 0.002 to 0.03 part by weight. If the amount of phosphoric acid added is too small, the phosphoric acid-containing effect tends to be insufficient, and conversely if too large, it tends to be difficult to obtain a film having a uniform thickness and appearance.

  When a boron compound is added, the amount added is usually 0.001 to 1 part by weight in terms of boron (analyzed by ICP emission spectrometry after ashing) with respect to 100 parts by weight of EVOH, preferably 0. 0.002 to 0.2 part by weight, particularly preferably 0.005 to 0.1 part by weight. If the addition amount of the boron compound is too small, the effect of adding the boron compound may not be sufficiently obtained. Conversely, if the addition amount is too large, it tends to be difficult to obtain a film having a uniform thickness and appearance.

  The amount of acetate and phosphate (including hydrogen phosphate) added is usually 0.0005 to 0 in terms of metal (after ashing and analyzed by ICP emission spectrometry) with respect to 100 parts by weight of EVOH. 0.1 part by weight, preferably 0.001 to 0.05 part by weight, particularly preferably 0.002 to 0.03 part by weight. If the added amount is too small, the content effect may not be sufficiently obtained. Conversely, if the added amount is too large, the resulting film tends to be colored or odorous. In addition, when adding 2 or more types of salts to EVOH, it is preferable that the total amount exists in the range of said addition amount.

<Description of ethylene-α-olefin copolymer (B)>
As the ethylene-α-olefin copolymer (B) used in the present invention, a known resin obtained by copolymerizing ethylene and an α-olefin having 4 to 20 carbon atoms such as propylene and butylene is used. It means an ethylene-α-olefin copolymer other than the ethylene-α-olefin copolymer (C) containing a carboxyl group described later. The ethylene-α-olefin copolymer (B) used in the present invention is not particularly limited, and for example, ethylene-propylene copolymer (EP), ethylene-butylene copolymer (EB), butylene-ethylene. A copolymer (BE) etc. can be mentioned. Among these, ethylene-propylene copolymer (EP), ethylene-butylene copolymer (from the viewpoint of excellent flexibility and improved flex resistance of a molded body and a multilayer structure using the obtained resin composition ( EB) is preferred, and ethylene-propylene copolymer (EP) is more preferred.
These may contain a functional group other than a carboxyl group, such as a hydroxyl group or a halogen group, but are preferably unmodified ethylene-α-olefin copolymers from the viewpoint of efficiently obtaining the effects of the present invention.

  The ethylene-α-olefin copolymer (B) used in the present invention usually preferably has a density of 0.80 to 0.96 g / cm 3, more preferably 0.82 to 0.92 g / cm 3, particularly Preferably it is 0.85-0.90 g / cm3.

  Further, the ethylene-α-olefin copolymer (B) used in the present invention has a bending elastic modulus at 23 ° C. and 50% RH of less than 150 MPa, preferably less than 100 MPa, particularly preferably less than 50 MPa. This is desirable from the viewpoint of good flexibility.

  In order to obtain a more excellent accumulated fatigue absorption effect, it is preferable that the density is 0.85 to 0.90 g / cm 3 and the flexural modulus at 23 ° C. and 50% RH is less than 50 MPa.

  Furthermore, the melting point of the ethylene-α-olefin copolymer is 0 ° C to 130 ° C, preferably 30 ° C to 100 ° C, more preferably 50 ° C to 80 ° C.

  The closer the melt viscosity of EVOH (A) and the ethylene-α-olefin copolymer (B) containing no carboxyl group are, the easier the melt kneading becomes, and the ethylene-α-olefin copolymer in the EVOH matrix becomes easier. A resin composition in which the polymer (B) is uniformly dispersed can be easily obtained, and as a result, a resin composition having excellent bending resistance can be easily obtained.

From such a point of view, the melt flow rate (MFR) of the ethylene-α-olefin copolymer (B) is usually 0.01 to 150 g / 10 min at 210 ° C. under a load of 2160 g, preferably It is preferably 0.1 to 50 g / 10 minutes, more preferably 1 to 25 g / 10 minutes, and particularly preferably 1.5 to 10 g / 10 minutes.
Furthermore, as MFR ratio of EVOH (A) and ethylene-α-olefin copolymer (B) not containing a carboxyl group, MFR ratio ((A) / (B) measured at 210 ° C. under a load of 2160 g) In general, it is 0.1 to 10, preferably 0.5 to 4, and more preferably 0.7 to 3.0.

  The above B component can be blended with a highly crystalline EVOH resin based on low crystallinity characteristics to obtain a resin composition with added flexibility.

<Description of carboxyl group-containing ethylene-α-olefin copolymer (C)>
The carboxyl group-containing ethylene-α-olefin copolymer (C) used in the present invention has a carboxyl group in either or both of the main chain and the side chain of the ethylene-α-olefin copolymer (B). It is an ethylene-α-olefin copolymer. The carboxyl group-containing ethylene-α-olefin copolymer (C) is obtained by using a part of the monomer constituting the ethylene-α-olefin copolymer (B) as an α, β-unsaturated carboxylic acid or an anhydride thereof. It can be obtained by copolymerizing instead of the monomer, or by introducing an α, β-unsaturated carboxylic acid or an anhydride thereof into a part of the side chain by a graft reaction such as radical addition.

  Specific examples of the α, β-unsaturated carboxylic acid or anhydride thereof include α, β-unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid; maleic acid, succinic acid, itaconic acid, and phthalic acid. Α, β-unsaturated dicarboxylic acid such as glycidyl acrylate, glycidyl methacrylate, hydroxyethyl acrylate, hydroxymethyl methacrylate and the like α, β-unsaturated monocarboxylic acid ester; maleic anhydride, succinic anhydride, itaconic anhydride, anhydrous Examples include α, β-unsaturated dicarboxylic acid anhydrides such as phthalic acid.

The carboxyl group-containing ethylene-α-olefin copolymer (C) in the resin composition of the present invention is an ethylene-α-olefin copolymer such as that used in the ethylene-α-olefin copolymer (B). A resin having a carboxyl group in either the main chain or the side chain, or both can be used.
As the carboxyl group-containing ethylene-α-olefin copolymer (C), a carboxyl group-containing ethylene-propylene copolymer (EP) and a carboxyl group-containing ethylene-butene copolymer are obtained in that the effects of the present invention can be obtained efficiently. (EB) is preferable, and a carboxyl group-containing ethylene-propylene copolymer (EP) is more preferable.

  The acid value of the carboxyl group-containing ethylene-α-olefin copolymer (C) is preferably 50 mgKOH / g or less. When the acid value is too high, the reaction point with the hydroxyl group in EVOH (A) is increased, a highly polymerized product is formed in the melt-kneading process, the stability during extrusion is lowered, and a good molded product is obtained. It tends to be difficult. The upper limit of the acid value is more preferably 30 mgKOH / g or less, and further preferably 20 mgKOH / g or less. On the other hand, when the acid value is too low, the compatibility with EVOH (A) decreases, and the amount of the resin attached to the die during extrusion tends to increase. The lower limit of the acid value is preferably 1 mgKOH / g or more, and more preferably 2 mgKOH / g or more.

  The density of the carboxyl group-containing ethylene-α-olefin copolymer (C) is usually 0.85 to 0.96 g / cm 3, preferably 0.85 to 0.92 g / cm 3, more preferably 0.85 to 0.9 g / cm @ 3. By using such a low density acid-modified ethylene-α-olefin copolymer (C), it is possible to obtain a molded article and a multilayer structure particularly excellent in bending resistance.

The closer the melt viscosity of EVOH (A) is to the melt viscosity of the carboxyl group-containing ethylene-α-olefin copolymer (C), the easier the melt kneading and the better the resin composition with excellent bending resistance and transparency. Easy to obtain.
From this point of view, the melt flow rate (MFR) of the carboxyl group-containing ethylene-α-olefin copolymer (C) is usually 0.01 to 150 g / 10 min at 210 ° C. under a load of 2160 g, preferably It is 0.1-50 g / 10min, More preferably, it is 1-25g / 10min, More preferably, it is 1.5-10g / 10min.
Furthermore, the ratio (A / C) of the MFR value of the A component and the MFR value of the C component is an MFR ratio measured under the conditions of 210 ° C. and a load of 2160 g, and is usually 0.1 to 10, preferably 0.5 to 7.5.

  As such a carboxyl group-containing ethylene-α-olefin copolymer (C), a commercially available product may be used. For example, “Admer”, “Toughmer” M series (manufactured by Mitsui Chemicals), “Binell”, “Fusabond” (manufactured by DuPont), “Orevac” (manufactured by Arkema), “Plexer” (manufactured by Equistar), and “Modic AP” (manufactured by Mitsubishi Chemical).

  The carboxyl group of the carboxyl group-containing ethylene-α-olefin copolymer (C) reacts with the hydroxyl group of EVOH (A) to produce a grafted product of the A component and the C component, and the grafted product becomes the A component and the B component. It is presumed that the component (B) can exist as a stable domain in the EVOH (A) matrix. Therefore, when the carboxyl group-containing material of the same kind of ethylene-α-olefin copolymer as the component (B) is used as the component (C), the affinity between the component (B) and the component (C) is further increased. This is preferable because the effects of the invention can be obtained more effectively.

<Description of ionomer (D)>
The ionomer (D) used in the present invention is a known resin, and is a thermoplastic resin having an ionic group in the side chain with respect to the hydrophobic polymer main chain.
Examples of the ionomer (D) include a carboxylic acid ionomer having a structure in which part or all of the carboxyl groups of the ethylene-unsaturated carboxylic acid copolymer are neutralized with metal ions, and the sulfonic acid groups of the sulfonic acid group-containing polymer. And sulfonic acid ionomers having a structure in which a part or all of these are neutralized with metal ions.

In the present invention, by blending such an ionomer (D), a film having a high level of flexibility and excellent gas barrier properties and film strength can be obtained.
Since the ionomer (D) is a polymer, there is little bleed-out to the outside of the resin composition, and it is effectively incorporated in the matrix EVOH (A) and the domain ethylene-α-olefin copolymer (B). Presumed to be captured. Furthermore, since the carboxyl group or the sulfonic acid group has a functional group neutralized with a metal salt, the reaction between the EVOH (A) and the acid-modified thermoplastic resin elastomer (B) is not hindered. A), ethylene-α-olefin copolymer (B) and carboxyl group-containing ethylene-α-olefin copolymer (C) interact with each other as an ionic cross-linking part, and are toughened against bending and impact. Presumed to be.

The metal ion that neutralizes the acid moiety, such as the ionomer carboxyl group or sulfonic acid group, is usually a monovalent metal ion such as lithium, sodium, potassium, rubidium, or cesium, or divalent such as calcium, magnesium, iron, or zinc. Examples thereof include metal ions, trivalent metal ions such as iron and aluminum. The metal cation content in the ionomer is usually in the range of 0.4 to 4 mol, preferably 0.6 to 2 mol, per kg of ionomer. Further, the neutralization degree is suitably used by neutralizing 15 to 80%, preferably 20 to 60% of the acid amount in the copolymer component with the metal cation.
In the ionomer used in the present invention, the metal ion that neutralizes the acid moiety is preferably a monovalent metal ion, particularly preferably a sodium ion, from the viewpoint of elasticity and flexibility.

  Specific examples of the carboxylic acid ionomer include ionomers such as carboxylate ionomers such as ethylene-unsaturated carboxylic acid copolymers, and specific examples of the sulfonic acid ionomer include polystyrene sulfonate (PSS). Examples include ionomers and ethylene sulfonate ionomers.

In the present invention, it is preferable to use a carboxylic acid ionomer from the viewpoint of affinity with EVOH (A), and it is particularly preferable to use an ionomer of an ethylene-unsaturated carboxylic acid copolymer.
Examples of the unsaturated carboxylic acid in the ionomer of the ethylene-unsaturated carboxylic acid copolymer include (meth) acrylic acid, maleic acid, fumaric acid, maleic anhydride, maleic acid monomethyl ester, maleic acid monoethyl ester, and the like. These can be used alone or in combination.

  The ethylene component content of the ethylene-unsaturated carboxylic acid random copolymer ionomer is usually 50 to 99% by weight, preferably 60 to 95% by weight. Moreover, an unsaturated carboxylic acid component is 1 to 50 weight% normally, Preferably it is 15 to 40 weight%.

  Further, the ionomer of the ethylene-unsaturated carboxylic acid copolymer may contain a small amount of other monomer that can be a copolymerization component (for example, less than 20% by weight), such as vinyl acetate. Unsaturated (meth) acrylic such as vinyl ester, methyl (meth) acrylate, ethyl (meth) acrylate, isobutyl (meth) acrylate, n-butyl (meth) acrylate, isooctyl (meth) acrylate Examples include acid esters.

  That is, as the ionomer (D) used in the present invention, a monovalent metal ion neutralized product of an ethylene- (meth) acrylic acid copolymer is preferable, and sodium of an ethylene- (meth) acrylic acid copolymer is particularly preferable. Ion neutralized product.

  The ionomer (D) preferably has a melting point of usually 70 to 120 ° C, preferably 80 to 110 ° C, particularly preferably 85 to 95 ° C. Moreover, MFR is 190 degreeC and a load of 2160g. Usually it is 0.05-100g / 10min, Preferably it is 0.1-50g / 10min, More preferably, it is 0.1-10g / 10min, Most preferably, it is 0.00. 5 to 1.5 g / 10 min.

  Examples of such commercially available ionomers (D) include commercially available products such as “Himiran” (Mitsui / DuPont Polychemical) and “Surlin” (DuPont).

<Resin composition>
The resin composition of the present invention comprises an ethylene-vinyl ester copolymer saponified product (A), an ethylene-α-olefin copolymer (B) (excluding the component (C)), a carboxyl group-containing ethylene-α. -Olefin copolymer (C) and ionomer (D) are contained.

  The matrix of the resin composition of the present invention is the component (A), and the mass ratio of the total amount of the component (A) and the components (B), (C), and (D) [(A) / ( (B) + (C) + (D))] is usually more than 50 / less than 50 to 99/1. Preferably it is 60 / 40-95 / 5, More preferably, it is 70 / 30-90 / 10. When this ratio is too small, gas barrier performance tends to be reduced. Moreover, when this ratio is too large, there exists a tendency for a softness | flexibility to fall.

  The domain of the resin composition of the present invention is mainly the component (B), and the mass ratio of the total amount of the component (A), the component (B) and the component (C) [(A) / ((B) + (C))] is usually 99/1 to 50/50. More preferably, it is 90 / 10-70 / 30. When this ratio is too small, gas barrier performance tends to be reduced. Moreover, when this ratio is too large, there exists a tendency for a softness | flexibility to fall.

  The component (C) in the present invention is a compatibilizer for the component (A) that is a matrix and the component (B) that is a domain. Therefore, the mass ratio [(B) / (C)] of the component (B) and the component (C) is usually 1/99 to 99/1, preferably 50/50 to 95/5, particularly preferably. 70/30 to 90/10. When this ratio is too small, the thermal stability of the resin composition tends to decrease. Moreover, when this ratio is too large, there exists a tendency for a softness | flexibility to fall.

  The content of the component (D) in the resin composition of the present invention is the mass ratio of the total amount of the components (A), (B), (C) and (D) [(D) / ((A ) + (B) + (C))] is usually 10/90 to 1/99. Preferably it is 7/93-2/98, More preferably, it is 5/95-3/97. When this ratio is too small, there exists a tendency for a softness | flexibility to fall. Moreover, when this ratio is too large, there exists a tendency for gas barrier performance to fall.

  The bending elastic modulus of the resin composition of the present invention was determined using an autograph (“AGS-H5kN” manufactured by Shimadzu Corporation) according to ISO 178 at 23 ° C. and 50% RH under a test speed of 2 mm / min. The measured value is usually 1900-2800 MPa, preferably 1900-2600 MPa. When this value is too large, the flexibility tends to decrease, and when it is too small, the resulting molded product tends to be deformed.

  In addition, content of the alkali metal in the resin composition of this invention is 200-2000 ppm normally in metal conversion, Preferably it is 300-1000 ppm, Most preferably, it is 400-800 ppm. When the content of the alkali metal salt is within the above range, the effect of the present invention tends to be obtained more effectively. The alkali metal content is such that when EVOH contains a low molecular alkali metal salt such as acetic acid, boric acid, potassium phosphate, sodium salt, etc., the ionomer (D) and the low molecular alkali metal salt Consider the total amount.

[Other ingredients]
In the EVOH layer, thermoplastic resins and additives other than EVOH and high ethylene EVOH are used within a range not inhibiting the effects of the present invention (for example, usually 5% by weight or less, preferably 1% by weight or less of the resin composition). It may contain.
Examples of thermoplastic resins other than the high ethylene EVOH include polyolefin resins; ethylene-vinyl acetate copolymer resins; vinyl ester resins; polyester resins; polyamide resins; polystyrene resins; Resin, ethylene-vinyl acetate copolymer resin, carboxyl group-containing resin obtained by addition reaction or graft reaction of unsaturated carboxylic acid such as maleic acid to vinyl ester resin, etc., among others, carboxyl group-containing ethylene-acetic acid A vinyl copolymer resin is preferred.
Examples of the additive include an antioxidant, a lubricant, an antistatic agent, a colorant, an ultraviolet absorber, a plasticizer, a heat stabilizer, a light stabilizer, a surfactant, an antibacterial agent, a desiccant, an antiblocking agent, and a difficult agent. Examples include a flame retardant, a crosslinking agent, a curing agent, a foaming agent, a crystal nucleating agent, an antifogging agent, a biodegradation additive, a silane coupling agent, and an oxygen absorber.

<Method for producing resin composition>
The method for preparing the resin composition of the present invention is not particularly limited.
(1) A method in which all components are dry blended and melt mixed;
(2) Dry blend two types of components (A), (B), (C), and (D) in advance and dry blend them with the remaining two types. Melt mixing method;
(3) A method in which (A) component, (B) component, and (C) component are previously dry-blended and melt-mixed, and then the pellets obtained by dry-blending with (D) component are melt-mixed;
(4) Create a master batch in which (B) component, (C) component, and (D) component are blended with a part of (A) component at high concentration, and dry blend with the remaining (A) component to melt mix how to;
(5) A method in which all components are dissolved and mixed in a solvent, and the solvent is distilled off;
(6) A method in which all components are dissolved and mixed in a good solvent, and the resin composition is precipitated in the poor solvent;
Etc.

Among these, (1) a method in which all components are dry-blended and melt-mixed is preferable in that the industrial productivity is good and uniform mixing is possible. In the melt mixing, a known machine can be employed. For example, it can be carried out using a kneader such as a kneader ruder, a single-screw or twin-screw extruder, a mixing roll, a Banbury mixer, a plast mill, etc., but it is industrially preferable to use a twin-screw extruder.
The resin composition of the present invention may be molded into various molded products when melt-extruded in an extruder and then extruded, or once a resin composition pellet is prepared, and then various molded products are molded by a known processing method. May be. The latter method is preferable from the viewpoint of the distribution and handling properties of the resin composition.
Moreover, when making it into a pellet, the shape usually includes a spherical shape, a cylindrical shape, a cubic shape, a rectangular parallelepiped shape, etc., and a cylindrical pellet is preferable, its diameter is usually 1 to 5 mm, and its length is usually 1 to 5 mm.

  The melt kneading temperature is usually in the range of 170 to 250 ° C., preferably 180 to 240 ° C., particularly preferably 180 to 230 ° C. as the set temperature of the extruder and the die. If the temperature is too low, the resin tends to be in an unmelted state and the processing state tends to become unstable. If the temperature is too high, the resin composition is thermally deteriorated, resulting in the quality of the obtained molded product. Tend to decrease. Further, if the D component is liquefied immediately below the hopper when the raw material is charged, the productivity may be lowered. Therefore, it is preferable to set the temperature just below the hopper to a temperature lower than the softening point of the D component.

<Multilayer structure>
The resin composition of the present invention is useful not only as a molded product formed of a resin composition alone, but also as a component of a multilayer structure, such as a single layer film (or sheet).
That is, the multilayer structure of the present invention is a multilayer structure having at least one layer composed of the resin composition of the present invention (hereinafter simply referred to as “resin composition layer”).

  Although it does not specifically limit as resin which comprises layers other than the resin composition layer which comprises the multilayer structure of this invention, Thermoplastic resins other than a resin composition (Hereinafter, it only describes with a thermoplastic resin) are mentioned. . For example, specifically, linear low density polyethylene, low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, ionomer, ethylene-propylene copolymer, ethylene-acrylic acid ester copolymer , Polypropylene, propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymer, polybutene, polypentene, or other olefin homopolymer or copolymer, cyclic polyolefin, or olefin homopolymer or copolymer. Broadly defined polyolefin resins such as those graft-modified with unsaturated carboxylic acids or esters thereof, polystyrene resins, polyesters, polyamides, copolymerized polyamides, polyvinyl chloride, polyvinylidene chloride, acrylic resins, vinyl ester resins, polyesters Elast A layer composed of a thermoplastic resin such as mer, polyurethane elastomer, chlorinated polyethylene, and chlorinated polypropylene. Among these, polyolefin resins are preferable from the viewpoint of mechanical strength and melt molding processability, and polyethylene and polypropylene are particularly preferable.

  In the multilayer structure of the present invention, the multilayer structure having the thermoplastic resin layer excellent in water barrier properties as an outer surface layer and the resin composition layer of the present invention as an intermediate layer is a packaging film having gas barrier properties, It is preferably used as a packaging container application. The thermoplastic resin having excellent water barrier properties is preferably a polyolefin resin, and particularly preferably polyethylene or polypropylene.

  The method for producing the multilayer structure is roughly divided into a method in which the resin composition is melted (melt molding method), a method in which the resin composition is dissolved in a solvent (for example, solution coating method), and the like. Is done. Among these, the melt molding method is preferable from the viewpoint of productivity.

  Specifically, for example, a method of melt-extruding a thermoplastic resin to a molded article (for example, a film or a sheet) of the resin composition of the present invention, a method of melt-extruding a resin composition layer to a substrate such as a thermoplastic resin, Examples thereof include a method of co-extrusion of the resin composition layer and the thermoplastic resin layer. Specifically, T-die extrusion, tubular extrusion, blow molding, profile extrusion, or the like is employed.

Furthermore, the resin composition film of the present invention and a base material such as a thermoplastic resin film are used with a known adhesive such as an organic titanium compound, an isocyanate compound, a polyethyleneimine compound, a polyester compound, or a polyurethane compound. A dry laminating method, a method of laminating with an adhesive resin layer interposed, and the like are employed.
In some cases, a co-injection method can also be employed.

  It does not specifically limit as adhesive resin which comprises an adhesive resin layer, A well-known thing can be used. Generally, a modified olefin containing a carboxyl group obtained by chemically bonding an unsaturated carboxylic acid or an anhydride thereof to an olefin polymer (the above-mentioned broadly defined polyolefin resin) by an addition reaction or a graft reaction. Examples thereof include maleic anhydride graft-modified polyethylene, maleic anhydride graft-modified polypropylene, maleic anhydride graft-modified ethylene-ethyl acrylate copolymer, maleic anhydride graft-modified ethylene-vinyl acetate. One type or a mixture of two or more types selected from copolymers and the like are preferred.

  In addition to these resin layers, the multilayer structure of the present invention is paper, metal foil, uniaxial or biaxially stretched plastic film or sheet, woven fabric, non-woven fabric, metal cotton strip, wood surface, aluminum or silica vapor deposition. You may have a layer combined with.

  As described above, the multilayer structure of the present invention is not particularly limited as long as it includes at least one resin composition layer according to the present invention, and the layer structure is not particularly limited. In order to prevent the deterioration, a multilayer structure in which the thermoplastic resin layer is an outer surface layer and the resin composition layer of the present invention is an intermediate layer is preferable.

The number of layers constituting the multilayer structure is not particularly limited, but is usually 3 to 20 layers, preferably 3 to 15 layers, and particularly preferably 3 to 10 layers. Although the layer structure is not particularly limited, when the EVOH composition layer is a (a1, a2,...) And the thermoplastic resin layer other than the EVOH resin is b (b1, b2,. Specifically, b / a / b, a / b / a, a1 / a2 / b, a / b1 / b2, b2 / b1 / a / b1 / b2, b2 / b1 / a / b1 / a / b1 / Arbitrary combinations such as b2 are possible.
Further, it may include a recycle layer containing a mixture of a resin composition and a thermoplastic resin other than EVOH, which is obtained by remelt molding an end portion or defective product generated in the process of producing the multilayer structure, When this recycled layer is R, b / a / R, R / b / a, b / R / a / b, b / R / a / R / b, b / a / R / a / b, b / R / a / R / a / R / b or the like is also possible.
Furthermore, a known adhesive resin layer may be interposed between the layers of the multilayer structure.

  From the viewpoint of preventing deterioration of the gas barrier performance of the resin composition layer, a multilayer structure in which the resin composition layer is an intermediate layer is most preferable so that moisture can be prevented from permeating into the resin composition layer. For example, specifically, a multilayer structure having a thermoplastic resin layer / adhesive resin layer / resin composition layer / adhesive resin layer / thermoplastic resin layer as a structural unit is most preferable.

  The thickness of the multilayer structure of the present invention is generally 1-1000 μm, preferably 5-700 μm, more preferably 10-500 μm. The thickness of the thermoplastic resin layer in the multilayer structure is not particularly limited, but is usually 0.1 to 1000 μm, preferably 1 to 500 μm. Although the thickness of a resin composition layer is not specifically limited, Usually, 0.1-500 micrometers, Preferably it is 1-100 micrometers. Although the thickness of an adhesive resin layer is not specifically limited, Usually, 0.1-250 micrometers, Preferably it is 1-100 micrometers.

  The thickness ratio of the thermoplastic resin layer / resin composition layer is usually more than 1 to 30, preferably 2 to 30, in the ratio of the thickest layers when there are a plurality of layers. The thickness ratio of the conductive resin layer / EVOH composition layer is usually 0.1 to 2, and preferably 0.1 to 1.

As described above, the multilayer structure of the present invention may be laminated with another thermoplastic resin or a substrate, and may be further subjected to a stretching treatment.
For stretching, a known stretching method can be used. Examples thereof include uniaxial stretching and biaxial stretching. In the case of biaxial stretching, both a simultaneous biaxial stretching method and a sequential biaxial stretching method can be employed. The stretching temperature is the temperature of the multilayer structure (the temperature in the vicinity of the multilayer structure) and is usually selected from the range of about 40 to 170 ° C, preferably about 60 to 160 ° C. A draw ratio is 2-50 times normally by an area ratio, Preferably it is 2-20 times. Further, heat setting may be performed after the stretching treatment. Thereby, the dimensional stability of a stretched film can be improved. The heat setting can be carried out by a known means, for example, by heating at 80 to 180 ° C., preferably 100 to 165 ° C., usually for about 2 to 600 seconds while maintaining the stretched film.

  The multilayer structure of the present invention is further 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, splitting as necessary. Processing or the like may be performed.

  The molded product produced using the multilayer structure of the present invention can also be applied to bag-shaped, cup-shaped and tray-shaped multilayer containers. In the case of a cup or tray-like container, usually a drawing method is employed, and specific examples include a vacuum forming method, a pressure forming method, a vacuum pressure forming method, a plug assist type vacuum pressure forming method, and the like. Furthermore, when a tube or bottle-shaped multilayer container is obtained from a multilayer parison (a hollow tubular preform before blow), a blow molding method is adopted. Specifically, an extrusion blow molding method (double-head type, mold transfer type, Parison shift type, rotary type, accumulator type, horizontal parison type, etc.), cold parison type blow molding method, injection blow molding method, biaxial stretch blow molding method (extrusion type cold parison biaxial stretch blow molding method, injection type cold) (Parison biaxial stretch blow molding method, injection molding inline biaxial stretch blow molding method, etc.).

  The multilayer structure of the present invention has an effect of being excellent in gas barrier properties and film strength while having a high level of flexibility. Therefore, it can be suitably applied to a molded product that is repeatedly deformed for a long time. Especially, it is preferable to use it as a bag-like container as a liquid container. In particular, it is preferable to use it as a bag-in-box, an inner container of the above-mentioned liquid-filled packaging structure or a laminate peeling container, that is, a container that comes into contact with the liquid as the contents.

Hereinafter, although the manufacturing method of bag-shaped liquid containers, such as a bag for bag-in-boxes, is demonstrated, the use of the multilayer structure of this invention is not limited to this.
A bag-like liquid container such as a bag for a bag-in-box can be manufactured mainly by a heat seal method and a blow molding method.

  In the heat sealing method, the laminated body formed by the co-extrusion method or the like is left as it is, or is overlapped in a double or triple as necessary, and a hole for hermetically attaching the liquid inlet is punched, and the hole is put into the hole. Then, the sealing plug of the liquid inlet formed in advance by injection molding is fused by the heat seal method. At this time, the laminated body in which the holes are punched and the other laminated body not subjected to the punching process are combined and heat-sealed in four directions to obtain a bag-like liquid container.

  In the blow molding method, the cylindrical multilayer structure (parison) extruded from a plurality of extruders by co-extrusion is clamped with a die and molded. The sealing plug of the liquid inlet is previously molded by injection molding and set in a mold, and is fused to the molding container at the time of blow molding. Then, a bag-like liquid container can be obtained by opening the liquid inlet.

  In particular, when the resin composition of the present invention is used as an inner container of a laminate peeling container that includes an outer layer and an inner layer, and the inner layer peels from the outer layer and shrinks as the content decreases, typically, blow molding The method is used. Usually, it is preferable to apply the resin composition of the present invention to a layer in contact with an outer container (that is, the outer layer) in the inner container (that is, the inner layer) of the delamination container. Furthermore, in the outer container (that is, the outer layer) of the delamination container, it is preferable to apply a resin that does not have adhesiveness with the resin composition of the present invention to the layer that is in contact with the inner container (that is, the inner layer). Typically, a polyolefin resin is used.

  The multilayer structure of the present invention includes, for example, foods such as mirin, soy sauce, sauce, noodle soup, and edible oil, wine, juice, milk, mineral water, sake, shochu, coffee, tea and other beverages, pharmaceuticals, cosmetics, hypoxia. It is suitably used as various liquid containers such as industrial chemicals such as sodium chlorate, developer and battery solution, agricultural chemicals such as liquid fertilizer, and detergents.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the description of the examples unless it exceeds the gist.
In the examples, “parts” and “%” mean weight basis unless otherwise specified.

〔Evaluation method〕
<Bending elastic modulus>
Using an autograph (“AGS-H5kN” manufactured by Shimadzu Corporation), the test speed was 2 mm / min under the conditions of 23 ° C. and 50% RH according to ISO178.

<Film strength: Film impact>
A multilayer structure was cut into a circle with a diameter of 80 mm and conditioned for 2 days in an environment of 23 ° C. and 50% RH was used as a sample. This sample was tested using a “film impact tester” (trade name) manufactured by Yasuda Seiki Co., Ltd. with a radius of impact ball R12.7 mm and a radius R6.35 mm. The amount of work required for the evaluation was evaluated.

<Gas barrier property: Oxygen transmission rate (OTR)>
The oxygen permeation rate (20 ° C., relative humidity: 65%) of a single layer film having a thickness of 30 μm of the resin composition was measured using an oxygen gas permeation measuring device (manufactured by Mocon, OX-TRAN 2/20).

Example 1
<Manufacture of EVOH resin pellets>
EVOH (A), ethylene-vinyl acetate copolymer saponified product (a1) (ethylene content 32 mol%, saponification degree 99.7 mol%, MFR 3.8 g / 10 min (210 ° C, load 2160 g)) Using.
As the ethylene-α-olefin copolymer (B), an ethylene-propylene copolymer (product name: “Tafmer P0180” manufactured by Mitsui Chemicals, MFR 4.5 g / 10 min (190 ° C., load 2160 g)) was used.
As the carboxyl group-containing ethylene-α-olefin copolymer (C), a maleic anhydride-modified ethylene-propylene copolymer elastomer (product name: “Tafmer MP0610” manufactured by Mitsui Chemicals) was used.
As an ionomer (D), a sodium neutralized product of ethylene- (meth) acrylic acid copolymer (product name: “HIMILAN 1707” manufactured by Mitsui DuPont Polychemicals, melting point 89 ° C., MFR 0.9 g / 10 min (190 ° C. , Load 2160 g)) was used.
The above components were used in the proportions shown in Table 1.

After dry blending the components shown in Table 1, the mixture was melt-kneaded under the following conditions in a twin-screw extruder, extruded into a strand shape, cut with a pelletizer, and cylindrical pellets of the resin composition were obtained.
Twin screw extruder Diameter (D) 30mm
L / D = 56
Screw rotation speed: 400rpm
Setting temperature: C2 / C3 / C4 / C5 / C6 / C7 / C8 / C9 / C10 / C11 / C12 / C13 / C14 / C15 / C16 / H / D = 50/80/190/220/230/240/230 / 230/230/240/240/240/240/240/240/230/230 ° C
Discharge rate: 30 kg / hr

[Production of molded products]
The obtained pellet was formed into a film with an extruder under the following conditions to produce a single layer film having a thickness of 30 μm, and the above evaluation was performed.
Diameter (D) 40mm
L / D = 28
Screw shape: Full flight Screw rotation speed: 20rpm
Set temperature: C1 / C2 / C3 / C4 / H / D = 200/220/220/220/220/220 ℃
Die: Coat hanger type Roll temperature: 80 ° C

  From the above results, the resin composition containing the ionomer (D) shows a lower flexural modulus than the resin composition containing no ionomer (D), and is good without significantly decreasing the film strength and gas barrier properties. It was found to show a good value.

In addition, Na amount in the resin composition of Example 1 was 715 ppm in metal conversion. Similarly, the amount of Na in Example 2 was 710 ppm in terms of metal, and 700 ppm in Example 3.
In contrast, the amount of Na in the resin composition of Comparative Example 1 was 120 ppm in terms of metal. Furthermore, in Comparative Example 2, it was 115 ppm.

Claims (3)

  Saponified ethylene-vinyl ester copolymer (A), ethylene-α-olefin copolymer (B) (excluding component (C)), carboxyl group-containing ethylene-α-olefin copolymer (C) And an ionomer (D).   A multilayer structure comprising at least one layer comprising the resin composition according to claim 1.   A liquid container comprising the multilayer structure according to claim 2.