JP6710944B2 - Resin composition and multilayer structure - Google Patents

Description

The present invention contains a saponified ethylene-vinyl ester copolymer (hereinafter, sometimes referred to as "EVOH resin"), a hydrate-forming carboxylate as a desiccant, and a basic metal salt. The present invention relates to a resin composition, and more specifically to an EVOH resin composition in which the viscosity increase with time during melt molding is small.

The EVOH resin has a very strong intermolecular force due to the hydrogen bond between the hydroxyl groups existing in the polymer side chain. Therefore, the crystallinity is high and the intermolecular force is high even in the amorphous portion, so that gas molecules such as oxygen hardly permeate the EVOH resin. Since such a film of EVOH resin exhibits an excellent gas barrier property, a multilayer structure containing an EVOH resin layer is widely used as a film for various kinds of packaging such as food and drink, and is used for retort treatment. Many are used for packaging films.

However, when a multilayer structure containing an EVOH resin layer is subjected to hot water treatment for a long time like retort treatment, water enters the EVOH resin layer from the end faces of the multilayer structure and breaks hydrogen bonds between molecules. It is known that the gas barrier performance is deteriorated by this.

In order to solve such a problem, a method of blending a desiccant with an EVOH resin is known (see, for example, Patent Document 1). For example, Patent Document 1 proposes a resin composition containing, as a desiccant, a partially dehydrated product or a completely dehydrated product of a hydrate of a carboxylic acid salt, which is a hydrate-forming salt, in EVOH resin.
Such a hydrate-forming salt means a dehydrated product of a metal salt hydrate having a property of incorporating water molecules as crystal water and containing crystal water in a less than saturated amount.

In this technique, the desiccant absorbs water that has entered the EVOH resin layer after hot water treatment as water of crystallization, prevents breakage of intermolecular hydrogen bonds, and suppresses deterioration of gas barrier performance.

JP, 2010-59418, A

When a multi-layer structure containing an EVOH resin layer is continuously melt-molded, the resin composition pellets are usually melt-kneaded in a melt-molding machine and then extruded and molded to obtain a molded product.

The EVOH resin belongs to a thermoplastic resin, but the viscosity at the time of melt-kneading may be relatively high depending on the kind of the hydrate-forming carboxylic salt added.

This is because the EVOH resin causes dehydration or crosslinking reaction by heat, and the metal component derived from the hydrate-forming carboxylic salt serves as a catalyst, or the strong acid component derived from the hydrate-forming carboxylic salt is It is speculated that the pH of the molten resin composition became acidic due to the presence.

Such an increase in viscosity during kneading causes retention of the resin in the extruder.

Further, if the resin stagnated in the extruder is immediately discharged, it is not a big problem, but in the case of melt-molding a resin showing a tendency of increasing viscosity by heating with time, such stagnant resin causes further increase in viscosity. As a result, it becomes less likely to be discharged, and as a result, a problem that thermal deterioration products are likely to occur is caused.

As a method for solving such a problem, it is possible to further balance the acid and the base in the system by further combining a basic metal salt, but a hydrate-forming carboxylate and a basic metal salt are used in combination. In such a case, if the obtained molded product is stored under high humidity for a long period of time, a white turbid pattern may occur.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a resin composition capable of suppressing an increase in viscosity during melt-kneading, and to store the obtained molded product for a long time under high humidity. Even if it is, it aims at providing the resin composition used as the raw material of the molded object which does not generate cloudiness.

The present inventor has conducted extensive studies in view of the above circumstances, and as a result, a resin composition containing an EVOH resin (A), a hydrate-forming carboxylate (B), and a basic metal salt (C), As the hydrate-forming carboxylic acid salt (B), a hydrate-forming carboxylic acid salt having a median diameter of 0.5 to 25 μm and the basic metal salt (C) are used in combination to perform melt kneading. The present invention has been completed by finding that it is possible to suppress an increase in viscosity at the time and to suppress a cloudy pattern when the obtained molded product is stored for a long time under high humidity.

Since the EVOH resin composition of the present invention can suppress thickening during melt-kneading, it has excellent long-run processability, and can suppress the occurrence of a cloudy pattern when the obtained molded product is stored under high humidity for a long time. Has excellent effect.

Hydrate-forming carboxylic acid salts are often used in fields such as food additives and intermediate raw materials for pharmaceuticals. It is generally sold and used as a coarse-grained powder (generally, a particle size standard of about 100 mesh pass) which is less likely to generate dust and is excellent in low cost due to the production of general-purpose equipment.
The hydrate-forming carboxylic acid salt described in Patent Document 1 is considered to be not a fine-grained hydrate-forming salt for reasons of economic efficiency (low cost) and market availability.

On the other hand, it is known that a resin composition containing an EVOH resin and a fine hydrate-forming salt is used as a raw material for a multilayer structure having a high gas barrier property (for example, JP 2008-75084 A). JP-A-63-113062).

This is to suppress the deterioration of the gas barrier property by forming a fine dispersion state of the desiccant particles in the EVOH resin by using the fine desiccant.

Therefore, when the hydrate-forming carboxylate and the basic metal salt are used in combination, the particle size of the hydrate-forming carboxylate is made fine to eliminate the appearance defect due to the cloudy pattern. Is not commonly done by one of ordinary skill in the art.

Hereinafter, the configuration of the present invention will be described in detail, but these show examples of preferred embodiments and are not limited to the contents thereof.

<EVOH resin composition>
The EVOH resin composition of the present invention is a resin composition containing an EVOH resin (A), a hydrate-forming carboxylate (B) having a median diameter of 0.5 to 25 μm, and a basic metal salt (C). It is a thing. Hereinafter, each component will be described.

First, the EVOH resin (A) used in the present invention will be described.

[EVOH resin (A)]
The EVOH resin used in the present invention is usually a resin obtained by saponifying a copolymer of ethylene and a vinyl ester monomer (ethylene-vinyl ester copolymer), which is a water-insoluble thermoplastic resin. Is. From the economical viewpoint, vinyl acetate is generally used as the vinyl ester-based monomer. The polymerization method can also be carried out by using any known polymerization method, for example, solution polymerization, suspension polymerization or emulsion polymerization, but solution polymerization using methanol as a solvent is generally used. Saponification of the obtained ethylene-vinyl ester copolymer can also be performed by a known method.
The EVOH resin produced in this manner mainly contains structural units derived from ethylene and vinyl alcohol structural units, and contains a small amount of vinyl ester structural units remaining without being saponified.

As the vinyl ester-based monomer, vinyl acetate is typically used from the viewpoint of market availability and efficiency of treating impurities during production. Other vinyl ester monomers include, for example, vinyl formate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl versatate, and other fats. Group vinyl ester, aromatic vinyl ester such as vinyl benzoate, and the like. Usually, an aliphatic vinyl ester having 3 to 20 carbon atoms, preferably 4 to 10 carbon atoms, and particularly preferably 4 to 7 carbon atoms is used. it can. These are usually used alone, but if necessary, a plurality of types may be used simultaneously.

For the ethylene and the vinyl ester-based monomer, petroleum-derived raw materials such as naphtha are usually used, but raw materials derived from natural gas such as shale gas, sugars contained in sugar cane, sugar beet, corn, potatoes, etc., starch. Or a monomer derived from a plant-derived raw material purified from components such as cellulose contained in rice, wheat, millet, grass plants and the like.

The content of the ethylene structural unit in the EVOH resin is a value measured based on ISO14663, and is usually 20 to 60 mol%, preferably 25 to 50 mol%, and particularly preferably 25 to 35 mol%. If the content is too low, the gas barrier property under high humidity and the melt moldability tend to be lowered, and conversely, if it is too high, the gas barrier property tends to be lowered.

The saponification degree of the vinyl ester component in the EVOH resin is a value measured based on JIS K6726 (however, the EVOH resin is a solution uniformly dissolved in a water/methanol solvent), and usually 90 to 100 mol%, preferably 95 to 100 mol %, particularly preferably 99 to 100 mol %. If the degree of saponification is too low, the gas barrier properties, thermal stability, moisture resistance, etc. tend to deteriorate.

The melt flow rate (MFR) (210° C., load 2,160 g) of the EVOH resin is usually 0.5 to 100 g/10 minutes, preferably 1 to 50 g/10 minutes, particularly preferably 3 to 35 g. /10 minutes. If the MFR is too large, the film-forming property tends to be unstable, and if it is too small, the viscosity tends to be too high and melt extrusion tends to be difficult.

The EVOH resin used in the present invention may further contain a structural unit derived from the following comonomer within a range that does not impair the effects of the present invention (for example, 10 mol% or less).
Examples of the comonomer include olefins such as propylene, 1-butene and isobutene, 3-butene-1-ol, 3-butene-1,2-diol, 4-penten-1-ol and 5-hexene-1,2. -Derivatives of hydroxy group-containing α-olefins such as diols and their esterified products, acylated products; acrylic acid, methacrylic acid, crotonic acid, (anhydrous) phthalic acid, (anhydrous) maleic acid, (anhydrous) itaconic acid, etc. Unsaturated acids or salts thereof or mono- or dialkyl esters having 1 to 18 carbon atoms; acrylamide, N-alkyl acrylamide having 1 to 18 carbon atoms, N,N-dimethylacrylamide, 2-acrylamidopropanesulfonic acid or its salt, acrylamide Acrylamides such as propyldimethylamine or acid salts thereof or quaternary salts thereof; methacrylamide, N-alkylmethacrylamides having 1 to 18 carbon atoms, N,N-dimethylmethacrylamide, 2-methacrylamidopropanesulfonic acid or salts thereof , Methacrylamides such as methacrylamidopropyldimethylamine or its acid salts or quaternary salts thereof; N-vinylamides such as N-vinylpyrrolidone, N-vinylformamide and N-vinylacetamide; cyanides such as acrylonitrile and methacrylonitrile. Vinyl chlorides; vinyl ethers such as alkyl vinyl ethers having 1 to 18 carbon atoms, hydroxyalkyl vinyl ethers, alkoxyalkyl vinyl ethers; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, vinyl bromide; Vinylsilanes such as trimethoxyvinylsilane; allyl halides such as allyl acetate and allyl chloride; allyl alcohols such as allyl alcohol and dimethoxyallyl alcohol; trimethyl-(3-acrylamido-3-dimethylpropyl)-ammonium chloride, acrylamide Examples thereof include comonomers such as 2-methylpropanesulfonic acid.

Furthermore, an EVOH-based resin that has been “post-modified” such as urethanized, acetalized, cyanoethylated, or oxyalkylenated can also be used.

In particular, an EVOH resin obtained by copolymerizing a hydroxy group-containing α-olefin is preferable in that the secondary moldability becomes good, and among them, an EVOH resin having 1,2-diol in the side chain is preferable.
The EVOH resin having such a 1,2-diol in its side chain has a 1,2-diol structural unit in its side chain. The 1,2-diol structural unit is specifically a structural unit represented by the following structural unit (1).

In the formula (1), R ¹ , R ² , and R ³ each independently represent a hydrogen atom or an organic group, X represents a single bond or a bonding chain, and R ⁴ , R ⁵ , and R ⁶ are independent of each other. Represents a hydrogen atom or an organic group.

The organic group in the 1,2-diol structural unit represented by the general formula (1) is not particularly limited, and examples thereof include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group. And saturated hydrocarbon groups such as tert-butyl group, aromatic hydrocarbon groups such as phenyl group and benzyl group, halogen atom, hydroxyl group, acyloxy group, alkoxycarbonyl group, carboxyl group and sulfonic acid group.
R ^{1 to} R ³ are preferably saturated hydrocarbon groups having 1 to 30 carbon atoms, particularly 1 to 15 carbon atoms, and more preferably 1 to 4 carbon atoms, or hydrogen atoms, and most preferably hydrogen atoms. R ^{4 to} R ⁶ are preferably an alkyl group having 1 to 30 carbon atoms, particularly preferably 1 to 15 carbon atoms, more preferably 1 to 4 carbon atoms, or a hydrogen atom, and most preferably a hydrogen atom. In particular, it is most preferable that R ^{1 to} R ⁶ are all hydrogen.

Further, X in the structural unit represented by the general formula (1) is typically a single bond.
The binding chain may be used as long as it does not impair the effects of the present invention. Such a bonding chain is not particularly limited, but alkylene, alkenylene, alkynylene, phenylene, hydrocarbon chains such as naphthylene (these hydrocarbons may be substituted with halogen such as fluorine, chlorine, bromine, etc.), _{-O -, - (CH 2 O} ) m -, - (OCH 2) m -, - (CH 2 O) mCH 2 - structure containing an ether binding site such as; -CO -, - COCO -, - CO ( CH ₂ )mCO-, a structure containing a carbonyl group such as —CO(C ₆ H ₄ )CO—; a structure containing a sulfur atom such as —S—, —CS—, —SO—, —SO ₂ —; -, - CONR -, - NRCO -, - CSNR -, - NRCS -, - structures including NRNR- such as nitrogen atoms; -HPO ₄ -, etc. structure containing a hetero atom such as structures containing phosphorus atoms; -Si _{(OR) 2 -, - OSi} (OR) 2 -, - OSi (OR) structure containing ₂ O- such as silicon _{atoms; -Ti (OR) 2 -,} - OTi (OR) 2 -, - OTi (OR ) A structure containing a titanium atom such as ₂ O-; a structure containing a metal atom such as a structure containing an aluminum atom such as -Al(OR)-, -OAl(OR)-, and -OAl(OR)O-. Be done.
In addition, each R is independently an arbitrary substituent, preferably a hydrogen atom or an alkyl group, and m is a natural number, usually 1 to 30, preferably 1 to 15, and more preferably 1 to 10. Among them, —CH ₂ OCH ₂ — and a hydrocarbon chain having 1 to 10 carbon atoms are preferable from the viewpoint of stability during production or use, and further a hydrocarbon chain having 1 to 6 carbon atoms, particularly 1 carbon atom. Is preferred.

The most preferable structure of the 1,2-diol structural unit represented by the above general formula (1) is that R ^{1 to} R ⁶ are all hydrogen atoms and X is a single bond. That is, the structural unit represented by the following structural formula (1a) is most preferable.

When the 1,2-diol structural unit represented by the general formula (1) is contained, the content is usually 0.1 to 20 mol %, further 0.1 to 15 mol %, and particularly 0.1 to 10. It is preferably 10 mol%.

Further, the EVOH resin used in the present invention may be a mixture with another different EVOH resin, and such another EVOH resin may be a 1,2-diol structural unit represented by the general formula (1). Examples thereof include those having different contents, those having different degrees of saponification, those having different degrees of polymerization, and those having different other copolymerization components.

The EVOH resin used in the present invention generally contains a compounding agent such as a heat stabilizer, an antioxidant, an antistatic agent, a colorant, an ultraviolet absorber, and the like, in a range that does not impair the effects of the present invention. Lubricants, plasticizers, light stabilizers, surfactants, antibacterial agents, drying agents, antiblocking agents, flame retardants, crosslinkers, curing agents, foaming agents, crystal nucleating agents, antifog agents, biodegradable additives, silanes. A coupling agent, an oxygen absorbent, etc. may be contained.

The heat stabilizer, for the purpose of improving various physical properties such as heat stability during melt molding, acetic acid, propionic acid, butyric acid, lauric acid, stearic acid, oleic acid, organic acids such as behenic acid or alkalis thereof. Metal salts (sodium, potassium, etc.), alkaline earth metal salts (calcium, magnesium, etc.), zinc salts, etc.; or inorganic acids, such as sulfuric acid, sulfurous acid, carbonic acid, phosphoric acid, boric acid, etc., or alkali metals thereof. Additives such as salts (sodium, potassium, etc.), alkaline earth metal salts (calcium, magnesium, etc.), zinc salts, etc. may be added. Among these, it is particularly preferable to add a boron compound containing acetic acid, boric acid and a salt thereof, an acetate salt or a phosphate salt.

When acetic acid is added, the addition amount thereof is usually 0.001 to 1 part by weight, preferably 0.005 to 0.2 part by weight, particularly preferably 0.010 to 0.1 part by weight based on 100 parts by weight of the EVOH resin. Parts by weight. If the added amount of acetic acid is too small, the effect of containing acetic acid tends to be insufficient, and if it is too large, it tends to be difficult to obtain a uniform film.

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

The amount of acetate and phosphate (including hydrogen phosphate) added is usually 0.0005 in terms of metal (calculated by ICP emission spectrometry after ashing) with respect to 100 parts by weight of EVOH resin. To 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 amount of addition is too small, the effect of inclusion may not be sufficiently obtained, while if it is too large, it tends to be difficult to obtain a uniform film. When two or more kinds of salts are added to the EVOH resin, it is preferable that the total amount thereof is within the above range of addition amount.

The method for adding acetic acid, a boron compound, an acetate salt, and a phosphate salt to the EVOH resin is not particularly limited. For example, i) a method in which a porous precipitate of an EVOH resin having a water content of 20 to 80% by weight is brought into contact with an aqueous solution of the additive, the additive is added to the porous precipitate, and then dried; ii) A method in which an additive is added to a uniform solution of EVOH resin (water/alcohol solution, etc.), and the mixture is extruded into a coagulating solution in a strand shape, and then the obtained strand is cut into pellets and further dried. iii. ) A method in which the EVOH resin and the additives are collectively mixed and then melt-kneaded with an extruder or the like; iv) The alkali (sodium hydroxide, potassium hydroxide, etc.) used in the saponification step during the production of the EVOH resin is used. Examples thereof include a method of neutralizing with an organic acid such as acetic acid and adjusting the amount of the remaining organic acid such as acetic acid and a by-produced salt by washing with water.
In order to obtain the effects of the present invention more remarkably, the methods i) and ii) which are excellent in dispersibility of the additive, and the method iv) when an organic acid and a salt thereof are contained are preferable.

Next, the hydrate-forming carboxylic acid salt (B) having a median diameter of 0.5 to 25 μm used in the present invention will be described.

[Hydrate-forming carboxylate (B) having a median diameter of 0.5 to 25 μm]
The hydrate-forming carboxylic acid salt (B) used in the present invention means a compound obtained by drying and dehydrating a hydrate of a carboxylic acid salt. That is, any carboxylic acid salt having a property of taking in water molecules as water of crystallization may be used.
The hydrate-forming carboxylate (B) is usually solid at room temperature and pressure.

As described above, the hydrate-forming carboxylic acid salt (B) can take in water of crystallization until it becomes stable as a saturated hydrate of the carboxylic acid salt hydrate. Therefore, the larger the amount of water of crystallization that can be taken into the saturated hydrate, the better the drying ability.
The hydrate-forming carboxylic acid salt (B) used in the present invention is a carboxylic acid salt whose stable hydrate is usually 1 to 20 hydrate, preferably 3 to 18 hydrate. It is an acid salt, and particularly preferably a carboxylic acid salt of 5 to 15 hydrate. When the content of water of crystallization contained in the stable hydrate is small, the ability to trap invading water tends to be small.
The anhydride of the maximum hydrate of such a carboxylate (when the water of crystallization is 0) or the partial hydrate (a metal salt containing less than the hydration number of the stable hydrate) is a desiccant. Anhydrate (when the water of crystallization is 0) is particularly preferable because it can be used as the barrel component B and has the ability to trap invading water. In the case of a partially dehydrated product (or partially hydrate), generally, if the amount of water of crystallization is less than 50% of the maximum hydration amount (preferably 30% or less, more preferably 10% or less), There is a tendency that the above water absorption characteristics can be satisfied.

In the present invention, the most characteristic feature of the hydrate-forming carboxylate (B) is that the median diameter is 0.5 to 25 μm, and the hydrate-forming carboxylate and the basic metal are It is possible to suppress the appearance defect due to the occurrence of a cloudy pattern of the molded product caused by the coexistence of salt.
Although the mechanism of poor appearance related to the occurrence of cloudiness is not known, when a molded product is stored at high humidity for a long time, part of the hydrate-forming carboxylic acid salt deliquesces into an EVOH resin composition. It is presumed that a dissolved hydrate-forming carboxylic acid salt migrates to the interface side of the EVOH resin composition layer and precipitates (bleeds out) to cause a phenomenon of poor appearance in a cloudy pattern. It is considered that the process of generating a cloudy pattern is promoted by using the organic metal salt together. It is speculated that the use of the hydrate-forming carboxylate having a thickness of 0.5 to 25 μm, which is a feature of the present invention, has somehow an effect of preventing the cloudy pattern generation process when the basic metal salt is used in combination. It

The median size is a particle size in which the larger side and the smaller side are equal when the particulate compound is divided into two from a certain particle size, and the cumulative volume is 100% when the total volume of the particulate compound is 100%. It is a numerical value defined by the volume particle diameter (d50) of 50%. That is, the median diameter (d50) is an index representing the average particle diameter of the particulate compound, and a larger value means a coarser and larger particle size, and a smaller value means a smaller particle size.

In the resin composition of the present invention, the range of the median diameter (d50) of the hydrate-forming carboxylate (B) is 0.5 to 25 μm, preferably 1 to 20 μm, and particularly preferably, a volume-based particle diameter. It is 2 to 10 μm.
If the median diameter (d50) is too small, the fluidity of the hydrate-forming carboxylic acid salt will be poor, and feed defects will tend to occur when compounded in an extruder. The appearance of a cloudy pattern tends to occur when stored for a long time under humidity, and the quality of the resin composition tends to be adversely affected.
The median diameter (d50) can be calculated by analyzing the cumulative volume distribution obtained using a commercially available laser scattering/diffraction particle size distribution measuring device.

Further, in the resin composition of the present invention, the 90% volume particle diameter (d90) of the hydrate-forming carboxylate (B) is also important. d90 is a numerical value defined by the volume particle diameter (d90) at which the cumulative volume becomes 90% when the total cumulative volume is 100%, and relates to the coarse particle component of the hydrate-forming carboxylate (B). It is a particle size index.

The 90% volume particle diameter (d90) of the hydrate-forming carboxylate (B) is in the range of 1 to 100 µm, preferably 2 to 50 µm, and particularly preferably 5 to 25 µm in terms of volume-based particle diameter.
If the 90% volume particle diameter (d90) is too small, the fluidity of the hydrate-forming carboxylic acid salt is poor, and feed defects tend to occur when compounded in an extruder. When a product is stored under high humidity for a long period of time, the appearance of a cloudy pattern becomes poor and foreign substances due to coarse particle components tend to increase, which tends to adversely affect the quality of the resin composition.
Note that the 90% volume particle diameter (d90) can be calculated by analyzing the cumulative volume distribution obtained by using a commercially available laser scattering/diffraction particle size distribution measuring device, similarly to the median diameter (d50). ..

Further, in the resin composition of the present invention, the ratio (d90/d50) of the 90% volume particle diameter (d90) to the median diameter (d50) of the hydrate-forming carboxylate (B) is also important. This numerical value is a particle size index relating to the particle size uniformity of the hydrate-forming carboxylate (B).
The range of d90/d50 of the hydrate-forming carboxylate (B) is 1.0 to 4.0, preferably 1.1 to 3.0, and particularly preferably 1.2 to 2.0. ..
If the d90/d50 is too small, the fluidity of the hydrate-forming carboxylic acid salt is poor, and feed failure tends to occur when compounded in an extruder. Inducing a decrease in feed stability when compounded with an acid salt extruder, a white cloudy pattern when the molded product is stored under high humidity for a long period of time, and foreign matter due to poor appearance and coarse particle components easily increase in resin composition. It tends to adversely affect the quality of goods.

The method for adjusting the hydrate-forming carboxylic acid salt (B) to have a median particle diameter of 0.5 to 25 μm is not particularly limited, but the hydrate-forming carboxylic acid salt may be compressed, impacted, It is obtained by crushing with at least one external force selected from the group consisting of shearing, rubbing and freezing.
More specifically, for example, a flow mill such as a jet mill; a ball mill such as a vibrating ball mill, a continuous rotary ball mill, a batch ball mill; a hammer mill such as an ACM mill; a wet pot mill, a pot mill such as a planet pot mill; a roller. A crusher such as a mill can be used. Among these, a jet mill, a ball mill, a hammer mill and a pot mill are preferable, and as a method for efficiently obtaining a hydrate-forming carboxylate having a median diameter of 0.5 to 25 μm, a pulverization treatment by a jet mill is most preferable.
The jet mill crushes the particulate compound by entraining the resin in the high-speed air stream ejected from the nozzle and crushing the particulate compound by the impact force and frictional force due to the collision between the resins or with the impact plate, and the temperature inside the device is unlikely to rise. Therefore, good crushing can be ensured. As the jet mill, for example, an air flow blowing type, a nosle passing type, a collision type, a fluidized bed jet blowing type, or the like can be used without particular limitation.

Examples of the kind of carboxylic acid salt in the hydrate-forming carboxylic acid salt (B) having a median diameter of 0.5 to 25 μm generally include aromatic carboxylic acid salts, aliphatic carboxylic acid salts, amino acid salts and the like. .. Such an aliphatic carboxylic acid salt or amino acid salt is preferably a saturated aliphatic carboxylic acid salt because it is considered that one that does not cause a graft reaction with the thermoplastic resin is preferable, and a saturated aliphatic polyvalent carboxylic acid is particularly preferable. Salt and saturated aliphatic hydroxycarboxylic acid salt.
The carboxylate is usually a metal salt or an ammonium salt, preferably an alkali metal salt of sodium or potassium and an alkaline earth metal salt of magnesium or calcium, particularly preferably an alkaline earth metal salt, Preferred is a magnesium salt.

The number of carbon atoms of the carboxylate is usually 1 to 12, preferably 2 to 12, and particularly preferably 4 to 12.
The valency of the carboxyl ion of the carboxylate is usually 1 to 4 valent, preferably 1 to 3 valent, and particularly preferably 2 to 3 valent.

In the hydrate-forming carboxylate (B) having a median diameter of 0.5 to 25 μm, the weight average molecular weight of the carboxylate hydrate is usually 50 to 1000, preferably 50 to 600, and particularly preferably. Is 50 to 400.

The above-mentioned carboxylic acid salt hydrates are specifically, for example, acetate salts such as sodium acetate (CH ₃ COONa·3H ₂ O) and calcium acetate ((CH ₃ COO) ₂ Ca·H ₂ O) as monovalent carboxylic acid salts. , Lactate such as calcium lactate ((CH ₃ CH(OH)COO) ₂ Ca·5H ₂ O), zinc gluconate ((CH ₂ (OH)CH(OH)CH(OH)CH(OH)CH(OH )COO) ₂ Zn.3H ₂ O), calcium gluconate ((CH ₂ (OH)CH(OH)CH(OH)CH(OH)CH(OH)COO) ₂ Ca·H ₂ O), etc. Salts, benzoates such as magnesium benzoate ((C ₆ H ₅ COO) ₂ Mg.4H ₂ O), calcium benzoate ((C ₆ H ₅ COO) ₂ Ca, 3H ₂ O), sodium malate (NaOOCCH) Malate such as (OH)CH ₂ COONa)·3H ₂ O) and calcium malate (OOCCH(OH)CH ₂ COO)Ca·H ₂ O); potassium oxalate ((COONa)) as a divalent carboxylate ₂ · H ₂ O), oxalates such as ammonium oxalate _{((COONH 4) 2 · H} 2 O), disodium succinate _{((CH 2 COONa) 2 ·} 6H 2 O), succinic acid dipotassium (( _{CH 2 COOK) 2 · 3H 2} O) succinate etc., L- glutamic acid potassium _{(HOOCCH (NH 2) CH 2} CH 2 COOK · H 2 O), L- sodium glutamate hydrogen (HOOCCH (NH ₂₎ CH ₂ CH ₂ COONa·H ₂ O), L-magnesium glutamate ((OOCCH(NH ₂ )CH ₂ CH ₂ COO)Mg·4H ₂ O), and other glutamate salts, sodium L-aspartate (HOOCCH ₂ CH(COOH)) NH ₂ · H ₂ O) aspartate such as, L- tartrate sodium hydrogen (HOOCCH (OH) CH (OH ) COONa · H 2 O), L- tartrate disodium (NaOCOCH (OH) CH (OH ) COONa · 2H ₂ O) and other tartrate salts; trivalent carboxylic acid salts such as tripotassium citrate (KOCOCH ₂ C(OH)(COOK)CH ₂ COOK·H ₂ O) and trisodium citrate ((C ₃ H ₅ O( COO) ₃ )Na ₃ .2H ₂ O), three dicitric acid Magnesium _{((C 3 H 5 O (} COO) 3) 2 Mg 3 · 14H 2 O), disuccinic tricalcium _{((C 3 H 5 O (} COO) 3) 2 Ca 3 · 4H 2 O) citric acid or the like salt; tetravalent carboxylate as ethylenediaminetetraacetic acid calcium disodium _{(Ca (OOCCH 2) 2 NCH} 2 CH 2 N (CH 2 COONa) 2 · 2H 2 O), disodium ethylenediaminetetraacetate ((HOOCCH _{2) 2} NCH ₂ CH ₂ N(CH ₂ COONa) ₂ ·2H ₂ O) and the like, and EDTA carboxylates such as EDTA tetraacetate.
The chemical formulas shown in parentheses above are chemical formulas of hydrates having the most water of hydration.

Among the above, oxalate, acetate, propionate, lactate, gluconate, malate, malonate, succinate, citrate, tartrate and EDTA carboxylate are aliphatic carboxylates. Glutamate and aspartate are amino acid salts.

From the viewpoint of productivity and safety, saturated aliphatic carboxylic acid salts and amino acid salts having a valency of 1 to 4 and a weight average molecular weight of 50 to 600 are preferable, and acetates, lactates and gluconates are particularly preferable. , Malate, malonate, succinate, citrate, tartrate, glutamate, aspartate. From the viewpoint of gas barrier properties after hot water treatment, saturated aliphatic polycarboxylic acid salts such as disodium succinate and dipotassium succinate, tripotassium citrate, trisodium citrate, trimagnesium dicitrate, disodium tartrate, etc. Aliphatic hydroxycarboxylic acid salts are preferable, and among them, trimagnesium dicitrate is particularly preferable from the viewpoint of shape stability during storage under high temperature and high humidity conditions.

Next, the basic metal salt (C) used in the present invention will be described.

[Basic metal salt (C)]
The basic metal salt (C) in the present invention means a compound which has a property of melting under the temperature condition (usually a temperature of 300° C. or lower) for melting and kneading an EVOH resin and shows basicity, and a base The hydrate-forming carboxylic acid salt (B) having a median diameter of 0.5 to 25 μm is obtained by melting the basic metal salt (C) during the melt molding by blending the basic metal salt (C). A neutralizing action works, and an effect of improving melt molding stability is obtained.

The type of the basic metal salt (C) of the present invention is a compound that acts as a proton acceptor according to the definition of Bronsted-Lowry, specifically, (1) an alkali metal or an alkaline earth metal and 25°C. Of a weak acid (higher carboxylic acid having 12 to 30 carbon atoms, carbonic acid, etc.) having an acid dissociation constant pKa in an aqueous solution of 3 or more, (2) a transition metal and an acid dissociation constant pKa in an aqueous solution of 25° C. are 3 It is a metal salt composed of a larger weak acid (a higher carboxylic acid having 12 to 30 carbon atoms, carbonic acid, etc.), and examples thereof include the following compounds.

(1) Metal salt/sodium salt (sodium stearate, sodium 12-hydroxystearate, sodium laurate, which is composed of an alkali metal or alkaline earth metal and a weak acid having an acid dissociation constant pKa of greater than 3 in an aqueous solution at 25° C. Sodium behenate, sodium montanate, sodium carbonate, etc.)
・ Potassium salt (potassium stearate, potassium laurate, potassium montanate, potassium carbonate, etc.)
・ Magnesium salt (magnesium stearate, 12-hydroxy magnesium stearate, magnesium laurate, magnesium behenate, magnesium montanate, magnesium carbonate, etc.)
・Calcium salt (calcium stearate, 12-hydroxy calcium stearate, calcium laurate, calcium behenate, calcium montanate, calcium carbonate, etc.)
(2) Metal salts/zinc salts (zinc stearate, 12-hydroxy) consisting of a transition metal and a weak acid having an acid dissociation constant pKa in an aqueous solution of 25° C. of more than 3 (higher carboxylic acid having 12 to 30 carbon atoms, carbonic acid, etc.) Zinc stearate, zinc laurate, zinc behenate, zinc montanate, etc.)
・Barium salts (barium stearate, barium 12-hydroxystearate, barium laurate, etc.)
・Aluminum salt (aluminum stearate, aluminum 12-hydroxystearate, etc.)
・Lithium salt (lithium stearate, 12-hydroxy lithium stearate, lithium laurate, lithium behenate, lithium montanate)

Among them, from the viewpoint of melt molding stability, (1) an alkali metal or an alkaline earth metal and a metal salt composed of a weak acid having an acid dissociation constant pKa of greater than 3 in an aqueous solution at 25° C. are preferable. A metal salt composed of a group metal and a weak acid (higher carboxylic acid having 12 to 30 carbon atoms, carbonic acid) having an acid dissociation constant pKa of 3 to 9 in an aqueous solution at 25°C is preferable, and acid dissociation in an aqueous solution of 25°C and sodium. A metal salt consisting of a weak acid having a constant pKa of 3 to 6 (higher monocarboxylic acid having 12 to 30 carbon atoms), a weak acid having a acid dissociation constant pKa of 3 to 6 in an aqueous solution of magnesium and 25°C (having 12 to 12 carbon atoms). Metal salts consisting of 30 higher monocarboxylic acids) are particularly preferred.

These basic metal salts (C) are usually used alone, but two or more kinds may be mixed and used.

The content of the basic metal salt (C) contained in the EVOH resin composition is, in the case of an alkali metal or an alkaline earth metal, a metal content measured by ICP emission spectrometry after sulfuric acid ashing of the EVOH resin composition. It can be quantified by conversion.

In the present invention, the hydrate-forming carboxylate (B) having a median diameter of 0.5 to 25 μm is preferably dispersed in the EVOH resin (A). Therefore, the blending amount of the hydrate-forming carboxylate (B) having a median diameter of 0.5 to 25 μm is not particularly limited according to the technical idea of the present invention that a specific compound is selected, and A corresponding effect can be expressed.

In the resin composition of the present invention, the content ratio of EVOH resin (A)/hydrate-forming carboxylate (B) having a median diameter of 0.5 to 25 μm is such that hydrate-forming metal salt is completely dehydrated. The weight ratio of the product is usually more than 50/50 and 99/1 or less, more preferably 70/30 to 97/3, particularly 80/20 to 95/5, and particularly 85/15 to 92/. 8 However, in such (B), the weight in the state of complete dehydration is meant.
If this ratio is too large, the effect of removing the water that has entered the EVOH resin (A) will be insufficient, and the gas barrier properties after hot water treatment (retort treatment) will tend to be insufficient. Does not have a layer of EVOH resin (A) formed, and tends to have insufficient gas barrier properties.

In addition, the resin composition of the present invention may be directly subjected to a molding process to obtain various molded products, or once the hydrate-forming carboxylate (B) having a median diameter of 0.5 to 25 μm can be obtained. A high-concentration composition (also referred to as a masterbatch) may be manufactured and diluted with an EVOH resin during molding to obtain various molded products. The content ratio of the EVOH resin (A) and the hydrate-forming carboxylate (B) having a median diameter of 0.5 to 25 μm in such a masterbatch is EVOH resin (A)/median diameter of 0.5 to 25 μm. The weight ratio of a hydrate-forming carboxylic acid salt (B) is usually 10/90 to less than 50/more than 50.

In the resin composition of the present invention, the content of the basic metal salt (C) with respect to the EVOH resin (A) is the amount of metal contained in the basic metal salt (C) with respect to 100 parts by weight of the EVOH resin (A). Converted, it is 0.001 to 1 part by weight, preferably 0.01 to 0.5 part by weight, and particularly preferably 0.02 to 0.1 part by weight.
If the content is too small, the melt viscosity increases when processed for a long time, and the fisheyes of the film tend to increase. On the contrary, if the content is too large, coloring and thermal decomposition easily occur and the quality of the resin composition increases. It tends to have an adverse effect.
When the EVOH resin (A) contains two or more kinds of salts, the total amount thereof is preferably within the above range.

In the resin composition of the present invention, the content ratio (C/B) of the basic metal salt (C)/the hydrate-forming carboxylate (B) having a median diameter of 0.5 to 25 μm is the basic metal. The weight ratio of the amount of metal contained in the salt (C) to the completely dehydrated hydrate-forming metal salt is usually 0.01/99.99 to 10/90, and more preferably 0.1/99.9. ˜5/95, especially 0.2/99.8 to 1/99. However, in such (B), the weight in the state of complete dehydration is meant.
If the ratio is too small, the melt viscosity tends to increase when processed for a long time, and the fish eyes of the film tend to increase.If it is too large, coloring and thermal decomposition easily occur and the resin composition It tends to have an adverse effect on the quality and melt moldability.

In the resin composition of the present invention, the content ratio of EVOH resin (A)/(sum of hydrate-forming carboxylate (B) having a median diameter of 0.5 to 25 μm and basic metal salt (C)) (A/(B+C)) is usually more than 50/less than 50 to 99/1 (more than 50/50 and 99/1 or less), more preferably 70/30 to 97/3, and particularly 75/25 to 95. /5, especially 80/20 to 92/8. However, in such (B), the weight in the state of complete dehydration is meant.
If this ratio is too large, the effect of removing the water that has entered the EVOH resin (A) will be insufficient, and the gas barrier properties after hot water treatment (retort treatment) will tend to be insufficient. Does not have a layer of EVOH resin (A) formed, and tends to have insufficient gas barrier properties.

[Other thermoplastic resin (D)]
The EVOH resin composition of the present invention contains a thermoplastic resin other than the EVOH resin (A) (“other thermoplastic resin (D)”) as a resin component in an amount of usually 30% by weight based on the EVOH resin (A). It may be contained below.

Specific examples of the raw material of the other thermoplastic resin (D) include linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ionomer, and ethylene. -Propylene copolymer, ethylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymer, ethylene-acrylic acid ester copolymer, polypropylene, propylene-α-olefin (α having 4 to 20 carbon atoms) -Olefin) copolymer, polybutene, homopolymers or copolymers of olefins such as polypentene, polycyclic olefins, or a broad definition of those homopolymers or copolymers of these olefins graft-modified with unsaturated carboxylic acids or their esters Polyolefin resin, polystyrene resin, polyester, polyamide, copolyamide, polyvinyl chloride, polyvinylidene chloride, acrylic resin, vinyl ester resin, polyester elastomer, polyurethane elastomer, polystyrene elastomer, chlorinated polyethylene, Examples include thermoplastic resins such as chlorinated polypropylene.

As the other thermoplastic resin (D), a petroleum-derived raw material such as naphtha is usually used, but a natural gas-derived raw material such as shale gas, sugar contained in sugar cane, sugar beet, corn, potato, etc., A plant-derived raw material purified from a component such as starch or a component such as cellulose contained in rice, wheat, millet, grass plants and the like may be used.

In particular, when the resin composition of the present invention is used as a multi-layered structure as a food packaging material, a polyamide resin is used in view of preventing elution of EVOH resin at the edges of the packaging material after hot water treatment of the packaging material. Is preferably blended. In the polyamide resin, the amide bond can form a network structure by the interaction with the OH group and/or the ester group of the EVOH resin, thereby preventing the EVOH resin from being eluted during the hot water treatment. You can Therefore, in the case of a resin composition used as a packaging material for retort foods or boiled foods, it is preferable to add a polyamide resin.

As the polyamide resin, known resins can be used.
For example, specifically, polycapramide (nylon 6), poly-ω-aminoheptanoic acid (nylon 7), poly-ω-aminononanoic acid (nylon 9), polyundecane amide (nylon 11), polylauryllactam (nylon 12). And homopolymers thereof. Examples of the copolyamide resin include polyethylenediamine adipamide (nylon 26), polytetramethylene adipamide (nylon 46), polyhexamethylene adipamide (nylon 66), polyhexamethylene sebacamide (nylon 610). ), polyhexamethylene dodecamide (nylon 612), polyoctamethylene adipamide (nylon 86), polydecamethylene adipamide (nylon 108), caprolactam/lauryllactam copolymer (nylon 6/12), caprolactam/ ω-aminononanoic acid copolymer (nylon 6/9), caprolactam/hexamethylene diammonium adipate copolymer (nylon 6/66), lauryl lactam/hexamethylene diammonium adipate copolymer (nylon 12/66), ethylenediamine Adipamide/hexamethylene diammonium adipate copolymer (nylon 26/66), caprolactam/hexamethylene diammonium adipate/hexamethylene diammonium sebacate copolymer (nylon 66/610), ethylene ammonium adipate/hexamethylene diester Aliphatic polyamides such as ammonium adipate/hexamethylene diammonium sebacate copolymer (nylon 6/66/610), polyhexamethylene isophthalamide, polyhexamethylene terephthalamide, polymethaxylylene adipamide, hexamethylene isophthalamide /Aromatic polyamides such as terephthalamide copolymer, poly-p-phenylene terephthalamide, poly-p-phenylene-3-4'diphenyl ether terephthalamide, amorphous polyamides, methylenebenzylamine of these polyamide resins, Examples thereof include those modified with aromatic amines such as metaxylylenediamine and metaxylylenediammonium adipate. Alternatively, these terminal-modified polyamide-based resins may be used, and the terminal-modified polyamide-based resin is preferable.

The terminal-modified polyamide-based resin is, for example, specifically a terminal-modified polyamide-based resin modified with a hydrocarbon group having 1 to 22 carbon atoms, and a commercially available product may be used. More specifically, for example, the number [a] of the terminal COOH groups of the terminal-modified polyamide-based resin and the terminal CONR ¹⁰ R ²⁰ group (wherein R ¹⁰ is a hydrocarbon group having 1 to 22 carbon atoms, R ²⁰ is a hydrogen atom or The number [b] of hydrocarbon groups having 1 to 22 carbon atoms is
100×b/(a+b)≧5
A terminal-modified polyamide resin satisfying the above conditions is preferably used.

The terminal-modified polyamide-based resin is an ordinary unmodified polyamide-based resin obtained by N-substituted amide modification of a carboxyl group of an ordinary unmodified polyamide-based resin, and is based on the total number of carboxyl groups contained in the polyamide-based resin before modification. A polyamide resin modified by 5% or more. If the amount of modification is too small, a large amount of carboxyl groups will be present in the polyamide-based resin, and such carboxyl groups will react with the EVOH resin during melt molding to generate gel and the like, resulting in a poor appearance of the film. Tends to be easy. Such a terminal-modified polyamide resin can be produced, for example, by the method described in JP-B-8-19302.

As the terminal adjuster, an amine capable of reacting with a carboxyl group is used in order to reduce the amount of the carboxyl group in the polyamide resin. The amine is a mono-substituted amine represented by HNR ¹⁰ R ²⁰ (R ²⁰ is a hydrogen atom) or a di-substituted amine. When R ¹⁰ and / or R ²⁰ of the HNR ¹⁰ R ²⁰ is an organic group, it may be a hydrocarbon group having no carboxyl group, a hydroxyl group in a range not inhibiting the gist of the present invention, an amino group, a carbonyl group, Although it may have another functional group, it is preferably an aliphatic hydrocarbon group. Specifically, R ¹⁰ and R ²⁰ are hydrocarbon groups having 1 to 22 carbon atoms, and preferably hydrocarbon groups having 5 to 20 carbon atoms. R ¹⁰ and R ²⁰ may be the same or different.

The content of unmodified terminal carboxyl groups of the terminal-modified polyamide resin is preferably low. The polyamide resin is dissolved in benzyl alcohol, and the value calculated by titration with 0.1N aqueous sodium hydroxide solution (molar equivalent to 1 g of polymer) is usually 0 to 50 µeq/g of polymer, preferably 0 to 30 µeq/g of polymer. And particularly preferably 0 to 25 μeq/g of polymer. If this value is too large, gel or the like is likely to occur during film formation, resulting in poor appearance, and the retort property tends to deteriorate. When the value is too small, there is no inconvenience in terms of physical properties, but productivity tends to decrease, so that it may remain to some extent. In this case, it is usually 5 to 50 μeq/g of polymer, more preferably 10 to 30 μeq/g of polymer, and particularly preferably 15 to 25 μeq/g of polymer.

Also, the terminal NH ₂ group of the unmodified polyamide-based resin is preferably modified with a hydrocarbon group having 1 to 22 carbon atoms as in the case of the terminal carboxyl group. Therefore, as the terminal adjuster used at this time, a carboxylic acid capable of reacting with an amino group in order to reduce the amount of the amino group in the polyamide resin, specifically, a monocarboxylic acid represented by RCOOH ( In the formula, R is a hydrocarbon group having 1 to 22 carbon atoms).

The melting point of the terminal-modified polyamide-based resin as described above is usually 200 to 250°C, preferably 200 to 230°C.

When using a polyamide resin as the other thermoplastic resin (D), the content weight ratio of EVOH resin/polyamide resin is usually 99/1 to 70/30, preferably 97/3 to 75/25, and particularly preferably It is preferably 95/5 to 85/15. When the ratio of the polyamide resin is too large, long-run moldability and gas barrier property tend to be insufficient. If the content ratio of the polyamide resin is too small, the effect of suppressing the elution of the EVOH resin after the hot water treatment tends to be insufficient.

The content weight ratio of the hydrate-forming carboxylate (B) having a median diameter of 0.5 to 25 μm to the polyamide resin is such that the hydrate-forming carboxylate having a median diameter of 0.5 to 25 μm. The content weight ratio as an acid salt is usually 95/5 to 5/95, preferably 70/30 to 30/70, and particularly preferably 60/40 to 40/60. If the ratio of the polyamide resin is too large, the gas barrier property after hot water treatment tends to be insufficient. If the ratio of the polyamide resin is too small, the EVOH resin tends to be easily eluted during the hot water treatment.

[Dispersant (E)]
Furthermore, it is preferable that the resin composition of the present invention further contains a dispersant.
The dispersant that can be used in the present invention is a dispersant that has been conventionally used in resin compositions, and examples thereof include higher fatty acids (for example, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, and oleic acid). Etc.), higher fatty acid metal salt (aluminum salt, calcium salt, zinc salt, magnesium salt, barium salt of higher fatty acid such as stearic acid), higher fatty acid ester (glycerin ester, methyl ester, isopropyl ester, butyl ester of higher fatty acid) , Octyl ester, etc., higher fatty acid amides (stearic acid amide, behenic acid amide, etc., saturated aliphatic amides, oleic acid amide, erucic acid amide, etc., unsaturated fatty acid amides, ethylenebisstearic acid amide, ethylenebisoleic acid amide, Ethylene bis erucic acid amide, bis fatty acid amides such as ethylene bislauric acid amide), low molecular weight polyolefins (for example, low molecular weight polyethylene having a molecular weight of about 500 to 10,000, or low molecular weight polypropylene, etc., or acid-modified products thereof), higher alcohols , Ester oligomers, fluorinated ethylene resins, etc., preferably higher fatty acids and/or metal salts thereof, esters, amides, more preferably alkaline earth metal stearates and/or higher fatty acid glycerin esters are used. Be done.

By blending the hydrate-forming carboxylate (B) having a median diameter of 0.5 to 25 μm, the torque value at the time of kneading the resin composition tends to increase. In addition, blending a polyamide resin that is effective in preventing elution of the EVOH resin also tends to increase the torque value during kneading of the EVOH resin. Such a tendency of thickening is not preferable from the viewpoint of requiring long-run property such as pellet production and film extrusion molding. In this respect, by adding a dispersant, the tendency of thickening can be suppressed, which is preferable. It is considered that the metal salt of higher fatty acid, especially the metal salt of stearic acid, may also act as a lubricant against the hydrate-forming metal salt inside the composition, which is an excellent inhibitor for thickening. Can be demonstrated.

The suppression of thickening of the EVOH resin composition (excellent long-run property) by blending the dispersant is exerted without being impaired even in the coexistence of the polyamide resin, which is effective in preventing elution of the EVOH resin. Therefore, when a polyamide resin is blended, by further blending a dispersant, it is possible to improve the productivity of a multilayer structure having an excellent appearance in which no water bubbles are generated even when it is left under high temperature and high humidity.

The blending amount of such a dispersant is not particularly limited, but it is preferably 0.01 to 5% by weight, more preferably 0.1 to 5% by weight, and further preferably in the resin composition. Is 0.5 to 3% by weight.

[Other additives (F)]
(F-1) Plate-like inorganic filler The EVOH resin composition of the present invention may further contain a plate-like inorganic filler for the purpose of improving gas barrier properties.

Examples of the plate-like inorganic filler include, for example, hydrous aluminum silicate as a main component, particles of which are plate-like kaolin, mica or smectite which is a layered silicate mineral, talc composed of magnesium hydroxide and silicate, and the like. Is mentioned. Of these, kaolin is preferably used. The type of kaolin is not particularly limited and may be calcined or not, but calcined kaolin is preferred.

The addition of these plate-like inorganic fillers further improves the gas barrier properties of the resin composition. Since the plate-like inorganic filler has a multi-layered structure, during kneading, the complete dehydration product or partial dehydration product of the hydrate-forming alkaline earth metal salt enters between the fillers, and the fillers collide with each other. To prevent destruction and fragmentation. Further, in the case of film formation, the plate-like surface of the plate-like filler is easily oriented in the plane direction of the film. Thus, it is considered that the plate-like inorganic filler oriented in the plane direction contributed to the oxygen blocking of the resin composition layer.

The compounding amount of such a plate-like inorganic filler is not particularly limited, but is usually 1 to 20% by weight, preferably 3 to 20% by weight, more preferably 5 to 15% by weight, based on the EVOH resin. Is.

(F-2) Oxygen Absorber The EVOH resin composition of the present invention may further contain an oxygen absorber for the purpose of improving gas barrier properties after hot water treatment (retort treatment).
An oxygen absorber is a compound or compound system that captures oxygen more quickly than the packaged contents. Specific examples thereof include an inorganic oxygen absorber, an organic oxygen absorber, and a composite oxygen absorber that uses a combination of an inorganic catalyst and an organic compound.

Inorganic oxygen absorbers include metals and metal compounds, and absorb oxygen by reacting these with oxygen. As the metal, a metal having a larger ionization tendency than hydrogen (Fe, Zn, Mg, Al, K, Ca, Ni, Sn, etc.) is preferable, and iron is representative. These metals are preferably used in powder form. As the iron powder, any conventionally known iron powder, such as reduced iron powder, atomized iron powder, electrolytic iron powder, etc., can be used without any particular limitation. The iron used may be iron that has been once oxidized and then reduced. Further, as the above metal compound, an oxygen-deficient metal compound is preferable. Here, examples of the oxygen-deficient metal compound include cerium oxide (CeO ₂ ), titanium oxide (TiO ₂ ), zinc oxide (ZnO), and the like. It is drawn out to become an oxygen deficient state, and exhibits oxygen absorbing ability by reacting with oxygen in the atmosphere. It is also preferable that the above metal and metal compound contain a metal halide or the like as a reaction accelerator.

Examples of the organic oxygen absorber include a hydroxyl group-containing compound, a quinone compound, a double bond-containing compound, and an oxidizable resin. Oxygen can be absorbed by the reaction of oxygen with the hydroxyl groups and double bonds contained in these. As the organic oxygen absorber, ring-opening polymers of cycloalkenes such as polyoctenylene, conjugated diene polymers such as butadiene, and cyclized products thereof are preferable.

The composite-type oxygen absorbent refers to a combination of a transition metal catalyst and an organic compound, which absorbs oxygen by exciting oxygen by the transition metal catalyst and reacting the organic compound with oxygen. It is a compound system that captures and absorbs oxygen by reacting the organic compound in the complex-type oxygen absorbent with oxygen earlier than the food contained in the package. The transition metal constituting the transition metal-based catalyst, for example, at least one selected from titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, zirconium, ruthenium, palladium, among them the phase with the resin Cobalt is preferable in terms of solubility, functionality as a catalyst, and safety. The organic compound is preferably a ring-opening polymer of cycloalkenes such as polyoctenylene which is an organic oxygen absorber, a conjugated diene polymer such as butadiene and a cyclized product thereof, and other organic compounds such as MXD nylon. The nitrogen-containing resin, the tertiary hydrogen-containing resin such as polypropylene, the polyalkylene ether bond-containing resin such as the block copolymer having a polyalkylene ether unit, and the anthraquinone polymer are preferable.

The content of such an oxygen absorbent is not particularly limited, but is usually 1 to 30% by weight, preferably 3 to 25% by weight, more preferably 5 to 20% by weight, based on the EVOH resin. is there.

The content ratio (mass ratio) of the transition metal-based catalyst and the organic compound is not particularly limited, but is 0.0001 to 5% by weight in terms of metal element based on the mass of the organic compound, and more preferably 0.0005. ˜1% by weight, more preferably 0.001 to 0.5% by weight.

(F-3) Other additives In addition to the above components, the EVOH resin composition of the present invention may optionally contain the effects of the present invention (for example, less than 5% by weight of the total resin composition). Plasticizers such as aliphatic polyhydric alcohols such as ethylene glycol, glycerin and hexanediol; saturated aliphatic amides (eg stearic acid amides), unsaturated fatty acid amides (eg oleic acid amides), bis fatty acid amides (eg ethylene Bisstearic acid amide), low molecular weight polyolefin (for example, low molecular weight polyethylene having a molecular weight of about 500 to 10,000, or low molecular weight polypropylene); antiblocking agent; antioxidant; colorant; antistatic agent; ultraviolet absorber; Antibacterial agent; Insoluble inorganic salt (for example, hydrotalcite); Filler (for example, inorganic filler); Surfactant, wax; Conjugated polyene compound, enediol group-containing substance (for example, phenols such as propyl gallate) ), aliphatic carbonyl compounds (eg, saturated aldehydes such as propanal, unsaturated aldehydes such as crotonaldehyde, saturated ketones such as acetone, etc.) and the like can be appropriately added.

The conjugated polyene compound is a so-called conjugated double bond having a structure in which carbon-carbon double bonds and carbon-carbon single bonds are alternately connected, and the number of carbon-carbon double bonds is 2 or more. Is a compound having The conjugated polyene compound is a conjugated diene having a structure in which two carbon-carbon double bonds and one carbon-carbon single bond are alternately connected, three carbon-carbon double bonds and two carbon- It may be a conjugated triene having a structure in which carbon single bonds are alternately connected, or a conjugated polyene compound having a structure in which a larger number of carbon-carbon double bonds and carbon-carbon single bonds are alternately connected. .. However, when the number of conjugated carbon-carbon double bonds is 8 or more, the molded product may be colored by the color of the conjugated polyene compound itself, so that the number of conjugated carbon-carbon double bonds is 7 or less. It is preferably a polyene. In addition, the above conjugated double bonds composed of two or more carbon-carbon double bonds may not be conjugated with each other, and a plurality of sets may be present in one molecule. For example, a compound having three conjugated trienes in the same molecule, such as tung oil, is also included in the conjugated polyene compound.

Specific examples of the conjugated polyene compound include isoprene, myrcene, farnesene, sembrene, sorbic acid, sorbic acid ester, sorbate, abietic acid and the like conjugated diene compound having two carbon-carbon double bonds; Conjugated triene compounds having three carbon-carbon double bonds such as 5-hexatriene, 2,4,6-octatriene-1-carboxylic acid, eleostearic acid, tung oil and cholecalciferol; cyclooctatetraene, Examples thereof include conjugated polyene compounds having 4 or more carbon-carbon double bonds such as 2,4,6,8-decatetraene-1-carboxylic acid, retinol and retinoic acid. These conjugated polyene compounds may be used alone or in combination of two or more.

The content of the conjugated polyene compound is usually 0.000001 to 1 part by weight, preferably 0.00001 to 1 part by weight, particularly preferably 0.0001 to 0.01 part by weight, based on 100 parts by weight of the EVOH resin. More preferably.
The conjugated polyene compound is preferably contained in the EVOH resin in advance.

Specific examples of the aliphatic carbonyl compound include saturated aldehydes, unsaturated aldehydes and saturated ketones. These aliphatic carbonyl compounds may be used alone or in combination of two or more.

As the saturated aldehyde, for example, saturated aliphatic aldehydes such as propanal, butanal, pentanal, hexanal, heptanal, octanal, cyclohexanecarbaldehyde, cyclopentylaldehyde, dimethylcyclohexanecarbaldehyde, methylcyclohexanecarbaldehyde, methylcyclopentylaldehyde are preferable, and At least one selected from the group consisting of Panard, Butanal, and Hexanal is more preferable.

Examples of the unsaturated aldehyde include acrolein, crotonaldehyde, methacrolein, 2-methylbutenal, 2-hexenal, 2,6-nonadienal, 2,4-hexadienal, 2,4,6-octatrienal, and 5 -Methyl-2-hexenal, cyclopentenyl aldehyde, cyclohexenyl aldehyde, and other aldehydes having a carbon-carbon double bond in the molecule; propiolaldehyde, 2-butyn-1-al, 2-pentyn-1-al, etc. An unsaturated aliphatic aldehyde such as an aldehyde having a carbon-carbon triple bond in the molecule is preferable, and at least one selected from the group consisting of crotonaldehyde, 2,4-hexadienal and 2,4,6-octatrienal. Is more preferable.

Examples of the saturated ketone include acetone, methyl ethyl ketone, 2-pentanone, 3-pentanone, 3-methyl-2-butanone, 2-hexanone, 3-hexanone, 4-methyl-2-pentanone, 2-methyl-3-. Pentanone, 3,3-dimethyl-2-butanone, 2-heptanone, 3-heptanone, 4-heptanone, 4-methyl-2-hexanone, 5-methyl-2-hexanone, 2,4-dimethyl-3-pentanone, 2-octanone, 3-methyl-2-heptanone, 5-methyl-3-heptanone, 3-octanone, 6-methyl-2-heptanone, 2,6-dimethyl-4-heptanone, methylcyclopentylketone, methylcyclohexylketone, Ethyl cyclopentyl ketone, saturated aliphatic ketones such as ethyl cyclohexyl ketone, cyclobutanone, cyclopentanone, cyclohexanone, cycloheptanone, cyclooctanone and the like saturated saturated ketones, saturated aliphatic ketones are preferred, acetone, methyl ethyl ketone and At least one selected from the group consisting of 2-hexanone is more preferable.

The lower limit of the content of the aliphatic carbonyl compound in the resin composition is 0.01 ppm, preferably 0.05 ppm, more preferably 0.1 ppm, even more preferably 0.15 ppm, particularly preferably 0.2 ppm. The upper limit of the content of the aliphatic carbonyl compound is 100 ppm, preferably 95 ppm, more preferably 50 ppm, further preferably 30 ppm, particularly preferably 20 ppm.

<Method for preparing EVOH resin composition>
In mixing the EVOH resin (A) with the hydrate-forming carboxylate (B) having a median diameter of 0.5 to 25 μm, a melt kneading method or a mechanical mixing method (pellet dry blending) is usually used. The melt kneading method is preferable. Specifically, a method of dry-blending each component after melt-blending or a method of mixing a hydrate-forming carboxylic acid salt (B) having a median diameter of 0.5 to 25 μm with a molten EVOH resin (A) is used. There is a method.

The mixing order is, for example, a method of simultaneously blending (1) component (A) and component (B); (2) first blending component (A) with an excessive amount of component (B) and blending (B) component After producing a high-concentration composition, an EVOH resin is added to this high-concentration composition to dilute the component (B) to obtain a desired composition.

Usually, the method (1) is used, but from the viewpoint of the cost at the time of distribution, a method in which the high-concentration composition (B) is once produced and diluted at the time of molding as in the method (2). Is also preferably adopted. At this time, the content weight ratio (A/masterbatch) of the EVOH resin (A) to the masterbatch is usually 10/90 to 99/1, and preferably 20/80 to, depending on the composition of the masterbatch. 95/5, particularly preferably 30/70 to 90/10.

As a mixing method, for example, any blending method such as a method of dry blending with a Banbury mixer or a method of melting and kneading with a single-screw or twin-screw extruder and pelletizing can be adopted. The melt-kneading temperature is usually 150 to 300°C, preferably 170 to 250°C.

By immersing the EVOH resin (A) and/or another thermoplastic resin (D) in an aqueous solution of a hydrate-forming carboxylate (B) having a median diameter of 0.5 to 25 μm, these The method (impregnation method) of impregnating the resin (B) with the component (B) and then drying the resin can also be used. However, this impregnation method tends to reduce the hydrate-forming ability of the hydrate-forming carboxylate (B) having a median diameter of 0.5 to 25 μm in a molded article obtained by molding the resin composition. It is difficult to adopt because it exists.
Further, the stable hydrate of the carboxylate as the component (B) is mixed with the EVOH resin (A), melt-kneaded, and then the hydrated water of the hydrate of the carboxylate is evaporated to obtain the resin composition of the present invention. Although a method of obtaining a product can be adopted, it is difficult to use such a method because foaming tends to occur in the resin composition.

The resin composition of the present invention can be directly obtained by melt-kneading the raw materials, but from the viewpoint of industrial handling, the resin composition pellets are obtained after the melt-kneading and melted. It is preferable to use a molding method to obtain a melt-molded product. From the viewpoint of economic efficiency, a method of melt-kneading with an extruder, extruding into a strand shape, cutting this and pelletizing is preferable.

The shape of such pellets includes, for example, a spherical shape, a cylindrical shape, a cubic shape, a rectangular parallelepiped shape, etc., but is usually a spherical shape (rugby ball shape) or a cylindrical shape, and the size thereof is convenient when used as a molding material later. From the viewpoint of, the diameter is usually 1 to 6 mm, preferably 2 to 5 mm in the case of a spherical shape, the height is usually 1 to 6 mm, preferably 2 to 5 mm, and the diameter of the bottom surface is usually 1 in the case of a cylindrical shape. -6 mm, preferably 2-5 mm, and the length is usually 1-6 mm, preferably 2-5 mm.

From the viewpoint of stabilizing the feedability during melt molding, it is also preferable to attach a lubricant to the surface of the obtained resin composition pellets. Types of lubricants include higher fatty acids (for example, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, etc.), higher fatty acid metal salts (aluminum salt, calcium salt, zinc salt, magnesium salt of higher fatty acid, Barium salt, etc., higher fatty acid ester (higher fatty acid methyl ester, isopropyl ester, butyl ester, octyl ester, etc.), higher fatty acid amide (stearic acid amide, behenic acid amide, etc., saturated aliphatic amide, oleic acid amide, erucic acid) Unsaturated fatty acid amides such as amides, ethylene bisstearic acid amides, ethylene bisoleic acid amides, ethylene bis erucic acid amides, bis fatty acid amides such as ethylene bislauric acid amides), low molecular weight polyolefins (for example, molecular weight of about 500 to 10,000) Low molecular weight polyethylene, low molecular weight polypropylene or the like, or acid modified products thereof, higher alcohols, ester oligomers, fluorinated ethylene resins and the like, preferably higher fatty acids and/or their metal salts, esters, amides, More preferably, higher fatty acid metal salts and/or higher fatty acid amides are used.

As the property of the lubricant, any property such as solid form (powder, fine powder, flakes, etc.), semi-solid form, liquid form, paste form, solution form, emulsion form (aqueous dispersion liquid) can be used. However, in order to efficiently obtain the resin composition pellets which are the object of the present invention, an emulsion is preferable.

As a method of adhering the lubricant to the surface of the resin composition pellets, a method of adhering the lubricant and the resin composition pellets by mixing them with a blender or the like, and dipping and adhering the resin composition pellets in a solution or dispersion of the lubricant A method, a method of spraying and attaching a solution or dispersion of a lubricant to the resin composition pellets, and the like can be mentioned.Preferably, the resin composition pellets are charged into a blender or the like and an emulsion-like lubricant is stirred, The solid content of the lubricant relative to 100 parts by weight of the resin composition pellets is 0.001 to 1 part by weight/hr, more preferably 0.01 to 0.1 part by weight/hr. It is preferable for uniform adhesion. Furthermore, in order to obtain a resin composition pellet in which all the lubricant attached to the pellet surface adheres to the pellet and the lubricant is not released in the melt molding machine, the surface temperature of the resin composition pellet is set to the melting point of the lubricant. The most preferable method is a method of bringing the temperature to -50°C or higher and contacting with a lubricant at a temperature lower than the melting point of the EVOH resin.

The amount of the lubricant added is preferably 10 to 1000 ppm, more preferably 20 to 500 ppm, and especially 50 to 250 ppm, based on the resin composition pellets, from the viewpoint of stable feedability during melt molding.

<Melted products>
The resin composition of the present invention can be molded into a film, sheet, cup, bottle or the like by a melt molding method. Examples of the melt molding method include an extrusion molding method (T-die extrusion, inflation extrusion, blow molding, melt spinning, profile extrusion, etc.) and an injection molding method. The melt molding temperature is often selected from the range of 150 to 300°C.

The melt-molded product containing the resin composition of the present invention may be used as it is for various purposes. At this time, the thickness of the layer of the resin composition is usually 1 to 5000 μm, preferably 5 to 4000 μm, and particularly preferably 10 to 3000 μm or more.

The resin composition layer is a layer formed from the resin composition of the present invention, and is usually obtained by performing the melt molding as described above. The melt-molded product obtained by molding the resin composition of the present invention is usually in a state where the component (B) is dispersed in the component (A) which is the base resin.

<Multilayer structure>
The multilayer structure of the present invention has at least one layer containing the resin composition of the present invention. A layer containing the resin composition of the present invention (hereinafter, simply referred to as “resin composition layer” means a layer containing the resin composition of the present invention) is laminated with another base material to further increase strength. Or other functions can be added.
As the base material, a thermoplastic resin other than EVOH resin (hereinafter referred to as "base material resin") is preferably used.

When the resin composition layer of the present invention is a (a1, a2,...) And the base resin layer is b (b1, b2,...), the layer structure of the multilayer structure is a/b, b/a/b, a/b/a, a1/a2/b, a/b1/b2, b2/b1/a/b1/b2, b2/b1/a/b1/a/b1/b2, etc. Combinations are possible. Further, when R is a recycled layer containing a mixture of the resin composition of the present invention and a thermoplastic resin, which is obtained by remelt-molding an end portion, a defective product or the like generated in the process of manufacturing the multilayer structure. , B/R/a, b/R/a/b, b/R/a/R/b, b/a/R/a/b, b/R/a/R/a/R/b, etc. It is also possible to do so. The total number of layers of the multilayer structure is usually 2 to 15, preferably 3 to 10.
In the above layer structure, an adhesive resin layer may be interposed between the respective layers, if necessary.

Among the above-mentioned multilayer structures, in particular, a unit (b/a/) of a multilayer structure including the resin composition layer of the present invention as an intermediate layer and providing a base resin layer as both side layers of the intermediate layer. A multilayer structure containing at least b or b/adhesive resin layer/a/adhesive resin layer/b) is preferable. In the sandwich-shaped multilayer structure sandwiching the resin composition layer of the present invention, a hydrophobic resin is provided in at least one layer (base resin layer b or adhesive resin layer) located on both sides of the resin composition layer. By using it, it is possible to prevent moisture absorption from the outside, and it is presumed that the drying effect of the component (B) can be exhibited more effectively. Therefore, in the case of a multilayer structure for a packaging material used for the purpose of being subjected to hot water treatment, a hydrophobic resin is used for at least one layer located on both sides of the resin composition layer in the unit of the multilayer structure. Thus, the oxygen permeability after the hot water treatment becomes good.

Examples of the above-mentioned "base resin" include linear low-density polyethylene, low-density polyethylene, ultra-low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-propylene (block and random) copolymers, ethylene-α. -Polyethylene resin such as olefin (C4-20 α-olefin) copolymer, polypropylene, polypropylene resin such as propylene-α-olefin (C4-20 α-olefin) copolymer, polybutene (Unmodified) polyolefin resins such as polypentene, polycyclic olefin resins (polymers having a cyclic olefin structure in the main chain and/or side chain), and grafts of these polyolefins with unsaturated carboxylic acids or their esters Polyolefin resin in a broad sense including modified olefin resin such as modified unsaturated carboxylic acid modified polyolefin resin, ionomer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic ester copolymer , Polyester resin, polyamide resin (including copolyamide), polyvinyl chloride, polyvinylidene chloride, acrylic resin, polystyrene, vinyl ester resin, polyester elastomer, polyurethane elastomer, polystyrene elastomer, chlorinated polyethylene , Halogenated polyolefins such as chlorinated polypropylene, aromatic or aliphatic polyketones, and the like.

As the above-mentioned "base resin" raw material, as in the above example, a petroleum-derived raw material such as naphtha is usually used, but a natural gas-derived raw material such as shale gas, sugarcane, sugar beet, corn, potato. A plant-derived raw material purified from components such as sugar and starch contained in the above, or components such as cellulose contained in rice, wheat, millet, grass plants and the like may be used.

Of these, hydrophobic resins such as polyamide-based resins, polyolefin-based resins, polyester-based resins, and polystyrene-based resins are preferred, and more preferably polyethylene-based resins, polypropylene-based resins, polycyclic olefin-based resins, and unsaturated resins thereof. It is a polyolefin resin such as a carboxylic acid-modified polyolefin resin, and a polycyclic olefin resin is particularly preferably used as the hydrophobic resin.

As the adhesive resin, a known adhesive resin can be used and may be appropriately selected depending on the type of the thermoplastic resin used for the base resin “b”. Typically, a modified polyolefin polymer containing a carboxyl group obtained by chemically bonding an unsaturated carboxylic acid or an anhydride thereof to a polyolefin resin by an addition reaction or a graft reaction can be mentioned. For example, maleic anhydride graft modified polyethylene, maleic anhydride graft modified polypropylene, maleic anhydride graft modified ethylene-propylene (block and random) copolymer, maleic anhydride graft modified ethylene-ethyl acrylate copolymer, maleic anhydride graft Examples include modified ethylene-vinyl acetate copolymers, maleic anhydride-modified polycyclic olefin-based resins, maleic anhydride graft-modified polyolefin-based resins, and the like, and one or a mixture of two or more selected from these can be used.

When an adhesive resin layer is used between the resin composition layer of the present invention and the base resin layer in a multilayer structure, the adhesive resin layer is at least one layer located on both sides of the resin composition layer. Therefore, it is preferable to use an adhesive resin having excellent hydrophobicity.

As the polycyclic olefin-based resin, a known resin (see, for example, JP-A-2003-103718, JP-A-5-177776, and JP-A-2003-504523) can be used. The polycyclic olefin-based resin has a lower moisture permeability than chain aliphatic polyolefins such as polyethylene and polypropylene. Therefore, in the multilayer structure of the sandwich structure using the resin composition layer of the present invention as an intermediate layer and using other thermoplastic resin layers or adhesive resin layers used on both sides thereof, other thermoplastic resin layers or adhesive properties By using a polycyclic olefin resin for the resin layer, it is possible to reduce the amount of moisture mixed from the outside due to moisture or hot water treatment, and as a result, the drying effect of the component (B) in the resin composition layer is effectively exhibited. The oxygen permeability after hot water treatment is good.

The above-mentioned base resin and adhesive resin include plasticizers, fillers, clays (such as those conventionally known) within a range that does not impair the gist of the present invention (for example, 30% by weight or less, preferably 10% by weight or less). Montmorillonite, etc.), a colorant, an antioxidant, an antistatic agent, a lubricant, a core material, an antiblocking agent, an ultraviolet absorber, a wax and the like.

Lamination of the resin composition of the present invention with the above-mentioned base resin (including the case where an adhesive resin layer is interposed) can be carried out by a known method. For example, a method of melt extrusion laminating a base resin on a film, sheet or the like of the resin composition of the present invention, a method of melt extrusion laminating a resin composition of the present invention on a base resin layer, a resin composition and a base resin. , A method of dry laminating the resin composition (layer) and the base resin (layer) with a known adhesive such as an organic titanium compound, an isocyanate compound, a polyester compound, a polyurethane compound, or a base material. Examples thereof include a method of applying a solution of the resin composition on the resin and then removing the solvent. Among these, the coextrusion method is preferable in consideration of cost and environment.

The above-mentioned multilayer structure is then subjected to a (heating) stretching treatment, if necessary. The stretching treatment may be uniaxial stretching or biaxial stretching, and in the case of biaxial stretching, it may be simultaneous stretching or sequential stretching. As a stretching method, a roll stretching method, a tenter stretching method, a tubular stretching method, a stretching blow method, a vacuum pressure molding or the like having a high stretching ratio can be adopted. The stretching temperature is a temperature in the vicinity of the multilayer structure and is usually selected from the range of 40 to 170°C, preferably about 60 to 160°C. If the stretching temperature is too low, the stretchability will be poor, and if it is too high, it will be difficult to maintain a stable stretched state.

For the purpose of imparting dimensional stability after stretching, heat setting may be performed next. The heat setting can be carried out by a well-known means. For example, the stretched film is usually heat-treated at 80 to 180° C., preferably 100 to 165° C. for usually 2 to 600 seconds while maintaining a tension state.
Further, when using a multilayer stretched film obtained from the resin composition of the present invention as a shrink film, in order to impart heat shrinkability, the above heat setting is not performed, for example, a cold air is applied to the stretched film. It suffices to perform processing such as applying and fixing by cooling.

In some cases, it is also possible to obtain a cup-shaped or tray-shaped multilayer container from the multilayer structure of the present invention. In that case, a draw forming method is usually adopted, and specifically, a vacuum forming method, a pressure forming method, a vacuum pressure forming method, a plug assist type vacuum pressure forming method and the like can be mentioned. Further, when a tube or a bottle-shaped multilayer container is obtained from a multilayer parison (a hollow tubular preform before being blown), a blow molding method is adopted. Specifically, an extrusion blow molding method (double-head type, mold moving 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 cold parison biaxial stretch blow molding method, injection cold Parison biaxial stretch blow molding method, injection molding in-line biaxial stretch blow molding method and the like). If necessary, the resulting laminate may be subjected to heat treatment, cooling treatment, rolling treatment, printing treatment, dry lamination treatment, solution or melt coating treatment, bag making processing, deep drawing processing, box processing, tube processing, split processing, etc. You can

The thickness of the multilayer structure (including stretched ones), and further the thickness of the resin composition layer, the base resin layer and the adhesive resin layer constituting the multilayer structure are the layer structure, the type of base resin, and the adhesiveness. The thickness of the multilayer structure (including stretched ones) is usually 10 to 5000 μm, preferably 30 to 3000 μm, and particularly preferably 50, although it cannot be generally stated depending on the type of resin, application, packaging form, required physical properties and the like. ˜2000 μm. The resin composition layer is usually 1 to 500 μm, preferably 3 to 300 μm, particularly preferably 5 to 200 μm, and the base resin layer is usually 5 to 30000 μm, preferably 10 to 20000 μm, particularly preferably 20 to 10000 μm, The adhesive resin layer has a thickness of usually 0.5 to 250 μm, preferably 1 to 150 μm, and particularly preferably 3 to 100 μm.

Furthermore, the thickness ratio of the resin composition layer and the base resin layer in the multilayer structure (resin composition layer/base resin layer) is the ratio of the thickest layers when there are a plurality of layers, It is usually 1/99 to 50/50, preferably 5/95 to 45/55, and particularly preferably 10/90 to 40/60. The thickness ratio of the resin composition layer and the adhesive resin layer in the multilayer structure (resin composition layer/adhesive resin layer) is usually 10 in terms of the ratio between the thickest layers when there are a plurality of layers. /90 to 99/1, preferably 20/80 to 95/5, particularly preferably 50/50 to 90/10.

The film and sheet obtained as described above, a bag and a cup made of a stretched film, a tray, a tube, a container made of a bottle or the like, a general food, mayonnaise, seasonings such as dressing, miso, etc. It is useful as a packaging material container for fermented foods, oil and fat foods such as salad oil, beverages, cosmetics, pharmaceuticals, and the like.
In particular, the layer made of the resin composition of the present invention has excellent gas barrier properties after hot water treatment, and thus is particularly useful as a packaging material for foods to be hot water treated.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to the description of the examples as long as the gist thereof is not exceeded.
In addition, "part" in the examples means weight basis unless otherwise specified.

<Example 1>
[EVOH resin (A)]
(A): Saponified ethylene-vinyl acetate copolymer having an ethylene structural unit content of 29 mol%, a saponification degree of 99.6 mol%, and a boric acid content of 500 ppm (calculated from boron analysis values) (MFR 4.3 g). /10 minutes (210° C., load 2160 g), volatile content 0.2%) was used.
[Hydrate-forming carboxylate (B)]
-(B-1): Dr. Trimagnesium dicitrate (anhydrous) micronized powder grade from Paul Lohmann was used.
(B-2): Trimagnesium dicitrate (anhydrous) USP Granular grade manufactured by JOST CHEMICAL was used.
[Basic metal salt (C)]
-(C) Calcium stearate (calcium stearate S made by NOF CORPORATION) was used.
[Other thermoplastic resin (D)]
・(D): Terminal-modified 6 nylon [Terminal COOH group: 22 μeq/g, number of terminal COOH groups is [a], terminal CONR10 R20 group (where R10 is a hydrocarbon group having 1 to 22 carbon atoms, and R20 is hydrogen) When the number of atoms or hydrocarbon groups having 1 to 22 carbon atoms is [b], 100×b/(a+b)=31, melting point 225° C., MFR 5 g/10 min (250° C., load 2160 g)] I was there.

[Evaluation of average particle size of cumulative volume distribution in hydrate-forming carboxylate (B)]
Regarding the median diameter (d50) and d90 of the hydrate-forming carboxylate (B), a hydrate-forming carboxylate was measured using a laser scattering/diffraction particle size distribution measuring device (LA-950V2 manufactured by Horiba Ltd.). The average particle diameters d50 and d90 were calculated from the cumulative volume distribution obtained by analyzing the acid salt (B) in an isopropanol solvent at a concentration of 0.01% with stirring and dispersion.
The results obtained are shown in Table 1.

[Evaluation of multilayer structure]
(1) Oxygen permeability after retort treatment (cc/m2·day·atm)
A sample piece (10 cm×10 cm) of the multilayer structure was subjected to retort treatment at 123° C. for 33 minutes using a hot water immersion type retort device (Hisaka Seisakusho), and then taken out. Three days after this retort treatment, an oxygen permeation rate (23° C., internal relative humidity: 90%, external relative humidity: 50%) was used using an oxygen gas permeation amount measuring device (OX-TRAN 2/20, manufactured by Mocon). ) Was measured.
(2) Occurrence of cloudiness pattern at 40° C. and 90% RH storage After leaving the multilayer structure for 40 days in a constant temperature and humidity chamber set at 40° C. and 90% relative humidity, the appearance of the multilayer structure is visually observed. The state (state of occurrence of cloudy pattern) was observed.
[Evaluation of resin composition]
(3) Kneading characteristics The prepared composition was kneaded using a melt kneading apparatus "Plastograph (manufactured by Brabender)" under the following melt kneading conditions after 5 minutes (T5) and 60 minutes (T60). The torque value (Nm) was measured.
"Melting and kneading conditions"
-Roller mixer: W50E (sample amount 55g)
・Device setting temperature: 250℃
・Kneader speed: 50ppm
(4) Long run property When the ratio (T60/T5) of the torque value (T60) after 60 minutes to the torque value (T5) after 5 minutes from the torque value (Nm) measured in (3) is 1 or more, It shows that the viscosity tends to increase. If the value is 0.001 to 0.7, it can be said that the long-run property is excellent.

[Production of resin composition]
EVOH resin (A), hydrate-forming carboxylate (B), basic metal salt (C), and other thermoplastic resin (D) are blended in the proportions shown in Table 2 and blended to form a resin. A composition was prepared.
Then, each resin composition was charged into a feeder, melt-kneaded under the following conditions with a twin-screw extruder having two mixing zones, extruded in a strand shape and cut with a drum-type pelletizer to form a cylindrical pellet (pellet diameter: 2 mm, pellet length: 3.5 mm, volatile matter: 0.3%) was obtained.
・Twin-screw extruder: diameter 32 mm, L/D=56 (manufactured by Japan Steel Works)
・Extruder set temperature:
C2/C3/C4/C5/C6/C7/C8/C9/C10/C11/C12/C13/C14/C15/C16/D
=90/90/110/150/220/230/230/230/230/230/230/230/230/230/230/230
・Screw speed: 150ppm
・Discharge rate: 12 kg/hour ・Cooling of strands: air cooling ・Pulling speed: 8.8 m/min

[Manufacture of multilayer structure]
The pellets of the prepared composition were fed to an extruder equipped with a T-die, and the die was heated to 230° C. to form a 3-kind 5-layer multilayer film having a thickness of 320 μm. The extrusion molding conditions were set as follows.
A chill roll in which cooling water is circulated by performing coextrusion under the following conditions using a coextrusion multilayer film forming apparatus having three extruders, a five-layer type 3 feed block, a multilayer film forming die, and a take-up machine. And cooled by a multi-layer structure (polypropylene ("Novatech PP EA7AD" manufactured by Japan Polypro Corporation)/adhesive resin ("Admer QF500" by Mitsui Chemicals, Inc.)/resin composition of the present invention/adhesive resin/polypropylene (thickness (Μm): 120/20/40/20/120)) was obtained.
・Middle layer extruder (EVOH): 40 mmφ single screw extruder (barrel temperature: 220° C.)
・Inner and outer layer extruder (PP): 40 mmφ single screw extruder (barrel temperature: 220°C)
・Middle/outer layer extruder (adhesive resin): 32 mmφ single screw extruder (barrel temperature: 220°C)
・Die: 3 types, 5 layers feed block die (die temperature: 220°C)
・Cooling roll temperature: 50℃

Using the resin composition pellets obtained above, the long-run property of this resin composition was evaluated. Further, the multilayer structure obtained above was used to evaluate the oxygen permeability after retort treatment, the state of water bubble generation, and the retort resistance. The results are summarized in Table 3.

(Table 1)

(Table 2)

(Table 3)

From the results of Examples 1 and 2, when the EVOH resin (A) was mixed with the hydrate-forming carboxylate (B) and the basic metal salt (C) having a median diameter of 0.5 to 25 μm. The oxygen permeability after retort treatment is smaller than that in the case where the hydrate-forming carboxylate (B) shown in Reference Example 2 is not added, and the film appearance at 40° C. and 90% RH storage is low. The long-run property index T60/T5 was 0.001 to 0.7, and good long-run processability was ensured.

On the other hand, from the results of Comparative Example 1, when the hydrate-forming carboxylate (B) having a median diameter of more than 25 μm was used under the same conditions as in Example 1, it was 30 at 40° C. and 90% RH storage. As the days passed, the film became cloudy and the appearance of the film deteriorated.

Furthermore, from the results of Comparative Example 2, when the hydrate-forming carboxylate (B) having a median diameter larger than 25 μm was used under the same conditions as in Example 2, 27 days after storage at 40° C. and 90% RH. After the lapse of time, a cloudy pattern was generated on the film and the film appearance was deteriorated. In addition, the long-run property index T60/T5 was 1 or more, and there was a tendency for thickening, resulting in poor long-run processability.

Reference Example 1 shows an experimental example in which the basic metal salt (C) was not blended under the same conditions as in Comparative Example 1, but when the basic metal salt (C) was not blended, 40° C., 90% Although the film appearance was good in RH storage, T60/T5, which is a long-run property index, was 1 or more, showing a tendency to increase in viscosity, and long-run processability deteriorated.

From Comparative Example 1, Comparative Example 2, and Reference Example 1, when the hydrate-forming carboxylate (B) having a median diameter of more than 25 μm and the basic metal salt (C) are used in combination, it is a subject of the present application. It can be seen that the film appearance and long-run processability at 40° C. and 90% RH storage are insufficient.

From Examples 1 and 2, Comparative Examples 1 and 2, and Reference Example 1, the combined use of the hydrate-forming carboxylate having a specific particle size and the basic metal salt resulted in an oxygen permeability after retort treatment. It is excellent and can suppress long-run processability during melt-kneading, and can eliminate the film appearance when stored at 40° C. and 90% RH.

The resin composition of the present invention can suppress thickening during melt-kneading of the EVOH resin composition, and thus is excellent in long-run processability. A multilayer structure including a layer formed by the resin composition of the present invention can suppress the deterioration of gas barrier properties by hot water treatment, and further, the film appearance in high humidity storage is also good, so hot water treatment, especially retort It is suitable as a packaging material for articles to be treated.

Claims (6)

Saponified ethylene-vinyl ester copolymer (A), hydrate-forming carboxylate (B) having a median diameter of 1 to 10 μm, and basic metal salt (C) (however, hydrate formation Sex power
A resin composition containing a rubonate (which is not the same as the rubonate (B)) . Ethylene-vinyl ester copolymer saponified product (A)/hydrate-forming carboxylate (
The content ratio (weight ratio) of B) as a completely dehydrated metal salt is 70/30 to 97/3.
The resin composition according to claim 1, wherein The hydrate-forming carboxylate (B) is an anhydride or partial water of the maximum hydrate of the carboxylate.
The resin composition according to claim 1 or 2, wherein the resin composition is a hydrate and the amount of water of crystallization is less than 50% of the maximum hydration amount.
Stuff. The basic metal salt (C) is mixed with an alkali metal or alkaline earth metal in an aqueous solution at 25°C.
A metal salt comprising a weak acid having an acid dissociation constant pKa of 3 to 9
Item 4. The resin composition according to any one of items 1 to 3. Further, a saponified product of an ethylene-vinyl ester copolymer containing a polyamide resin (A)
/Polyamide-based resin (weight ratio) is 99/1 to 70/30.
The resin composition according to any one of 1 to 4. Multilayer structure, characterized in that it comprises at least one layer containing the resin composition according to any one of claims 1-5.