JP2019007004A - Ethylene-vinyl alcohol-based copolymer composition, pellet consisting of the same, and multilayer structure using the same - Google Patents

Abstract

The present invention provides an ethylene-vinyl alcohol copolymer composition and a multilayer structure which have a good ultraviolet absorbing ability without blending a known ultraviolet absorber, have excellent thermal stability, and have suppressed coloring. To do. An ethylene-vinyl alcohol copolymer composition comprising an ethylene-vinyl alcohol copolymer (A), a fatty acid amide (B), and an iron compound (C), wherein the iron compound (C) comprises: An ethylene-vinyl alcohol copolymer composition characterized in that the content is 0.01 to 5 ppm in terms of metal per weight of the resin composition. [Selection figure] None

Description

  The present invention relates to an EVOH resin composition mainly composed of an ethylene-vinyl alcohol copolymer (hereinafter sometimes abbreviated as “EVOH resin”), a pellet comprising the same, and a multilayer structure having a layer comprising the same. More particularly, the present invention relates to an EVOH resin composition having ultraviolet absorbing ability, a pellet made of such an EVOH resin composition, and a multilayer structure having a layer made of the same.

  EVOH resin is excellent in transparency, gas barrier properties such as oxygen, aroma retention, solvent resistance, oil resistance, mechanical strength, etc., molded into films, sheets, bottles, etc., food packaging materials, pharmaceutical packaging materials, Widely used as various packaging materials such as industrial chemical packaging materials and agricultural chemical packaging materials.

  However, many foods and medicines are deteriorated or deteriorated by ultraviolet rays, and the packaging materials are required to have ultraviolet absorbing ability. As a method for imparting ultraviolet absorbing ability to a packaging material, it is common to mix an ultraviolet absorber in a resin used as a packaging material. For example, in a laminated structure in which layers made of polyolefin and EVOH resin are laminated, a laminated structure that reduces the transmittance of ultraviolet rays by kneading an ultraviolet absorber into a part or all of the layers is proposed. (For example, refer to Patent Document 1).

  Patent Document 1: Japanese Patent Application Laid-Open No. 2008-230112

  However, since UV absorbers are generally low molecular weight compounds, they can easily migrate through the resin after forming a molded product, and can move to the layer surface during use and come into contact with the contents or make the surface sticky. It had the problem that. Moreover, in order to obtain sufficient ultraviolet absorbing ability, it is necessary to mix | blend a large amount of ultraviolet absorbers in resin, As a result, there exists a tendency to reduce a resin characteristic.

  In order to solve such a problem and obtain an EVOH resin composition having a good ultraviolet absorbing ability without blending a known ultraviolet absorber, the present inventors recalled using an iron compound. However, when the EVOH resin composition contains an iron compound, although there is an improvement in ultraviolet absorption capacity and thermal stability in proportion to the amount, it tends to be colored during melt molding.

  That is, the present invention provides an EVOH resin composition and a multilayer structure that have an ultraviolet absorbing ability even when a known ultraviolet absorber is not blended, are excellent in thermal stability, and are suppressed from being colored.

In the present invention, as a result of intensive studies in view of the above circumstances, a resin composition obtained by using a specific trace amount of an iron compound and a fatty acid amide in combination with an EVOH resin has an ultraviolet absorbing ability and is excellent in thermal stability. The inventors have found that coloring is suppressed and have completed the present invention.
That is, the present invention is an EVOH resin composition containing an EVOH resin (A), a fatty acid amide (B) and an iron compound (C), wherein the content of the iron compound (C) is per weight of the EVOH resin composition. The first gist is an EVOH resin composition characterized by being 0.01 to 5 ppm in terms of metal. Moreover, this invention makes the 2nd summary the pellet which consists of said EVOH resin composition. Moreover, this invention makes the 3rd summary the multilayer structure which has a layer which consists of said EVOH resin composition.

  The EVOH resin composition of the present invention is an EVOH resin composition containing an EVOH resin (A), a fatty acid amide (B) and an iron compound (C), wherein the content of the iron compound (C) is the EVOH resin composition. Since it is 0.01 to 5 ppm in terms of metal per weight of the object, it has ultraviolet absorbing ability, excellent thermal stability, and coloring without using an ultraviolet absorber that may cause surface migration or resin property inhibition. Excellent suppression of

  The multilayer structure having a layer containing the EVOH resin composition of the present invention is particularly useful as a packaging material for foods because it has ultraviolet absorbing ability, excellent thermal stability, and coloring is suppressed. .

  Hereinafter, although it demonstrates in detail about the structure of this invention, these show an example of a desirable embodiment and are not specified by these content.

The EVOH resin composition of the present invention contains EVOH resin (A) as a main component and contains fatty acid amide (B) and iron compound (C). In the EVOH resin composition of the present invention, the base resin is an EVOH resin. That is, the EVOH resin content in the EVOH resin composition is usually 70% by weight or more, preferably 80% by weight or more, more preferably 90% by weight or more, and particularly preferably 95% by weight or more. .
Each component will be described below.

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

  As the vinyl ester monomer, vinyl acetate is typically used from the viewpoint of market availability and good impurity treatment efficiency during production. Examples of other vinyl ester monomers include, for example, fats such as vinyl formate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, and vinyl versatate. Aromatic vinyl esters such as aromatic vinyl esters and vinyl benzoates, and the like. Usually, aliphatic vinyl esters having 3 to 20 carbon atoms, preferably 4 to 10 carbon atoms, particularly preferably 4 to 7 carbon atoms are used. it can. These are usually used alone, but a plurality of them may be used simultaneously as necessary.

The content of the ethylene structural unit in the EVOH resin (A) can be controlled by the pressure of ethylene when copolymerizing the vinyl ester monomer and ethylene, and is usually 20 to 60 mol%, preferably 25 to 50 mol. %, Particularly preferably 25 to 48 mol%. When the content is too low, the gas barrier property and melt moldability under high humidity tend to be lowered, and when it is too high, the gas barrier property tends to be lowered.
In addition, content of this ethylene structural unit can be measured based on ISO14663.

The saponification degree of the vinyl ester component in the EVOH resin (A) is determined by the amount of saponification catalyst (usually an alkaline catalyst such as sodium hydroxide is used) and the temperature when saponifying the ethylene-vinyl ester copolymer. The amount is usually 90 to 100 mol%, preferably 95 to 100 mol%, particularly preferably 99 to 100 mol%. When the degree of saponification is too low, gas barrier properties, thermal stability, moisture resistance and the like tend to decrease.
The degree of saponification of the EVOH resin (A) can be measured based on JIS K6726 (however, the EVOH resin is a solution uniformly dissolved in water / methanol solvent).

Further, the melt flow rate (MFR) (210 ° C., load 2,160 g) of the EVOH resin (A) is usually 0.5 to 100 g / 10 minutes, preferably 1 to 50 g / 10 minutes, particularly preferably. 3 to 35 g / 10 min. When the MFR is too large, the film forming property tends to be unstable, and when it is too small, the viscosity becomes too high and melt extrusion tends to be difficult.
Such MFR serves as an index of the degree of polymerization of the EVOH resin (A), and can be adjusted by the amount of polymerization initiator and the amount of solvent when copolymerizing ethylene and a vinyl ester monomer.

The EVOH resin (A) used in the present invention further contains structural units derived from the following comonomer within a range not inhibiting the effects of the present invention (for example, 10 mol% or less of the EVOH resin). Also good.
Examples of the comonomer include olefins such as propylene, 1-butene, and isobutene, 3-buten-1-ol, 3-butene-1,2-diol, 4-penten-1-ol, and 5-hexene-1,2. -Derivatives such as hydroxy group-containing α-olefins such as diols, esterified products and acylated products thereof; hydroxyalkylvinylidenes such as 2-methylenepropane-1,3-diol and 3-methylenepentane-1,5-diol; Hydroxyalkylvinylidene diacetates such as 1,3-diacetoxy-2-methylenepropane, 1,3-dipropionyloxy-2-methylenepropane, 1,3-dibutyryloxy-2-methylenepropane; acrylic acid, methacrylic acid , Crotonic acid, (anhydrous) phthalic acid, (anhydrous) maleic acid, (anhydrous) itaconic acid, etc. Unsaturated acids or salts thereof, 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 salts thereof, acrylamide Acrylamides such as propyldimethylamine or acid salts thereof or quaternary salts thereof; methacrylamide, N-alkyl methacrylamide having 1 to 18 carbon atoms, N, N-dimethylmethacrylamide, 2-methacrylamide propanesulfonic 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; acrylic Vinyl cyanides such as nitrile and methacrylonitrile; vinyl ethers such as alkyl vinyl ether, hydroxyalkyl vinyl ether and alkoxyalkyl vinyl ether having 1 to 18 carbon atoms; vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, vinyl bromide, etc. Vinyl silanes such as trimethoxyvinyl silane; allyl halide compounds such as allyl acetate and allyl chloride; allyl alcohols such as allyl alcohol and dimethoxyallyl alcohol; trimethyl- (3-acrylamido-3-dimethyl) And a comonomer such as propyl) -ammonium chloride and acrylamide-2-methylpropanesulfonic acid. These may be used alone or in combination of two or more.

In particular, an EVOH resin having a primary hydroxyl group in the side chain is preferable in that the secondary moldability is improved while maintaining gas barrier properties, and among them, an EVOH resin obtained by copolymerizing a hydroxy group-containing α-olefin is preferable. In particular, EVOH resins having a 1,2-diol structure in the side chain are preferred.
In particular, when the EVOH resin has a primary hydroxyl group in the side chain, the content of the structural unit derived from the monomer having the primary hydroxyl group is usually from 0.1 to 20 mol%, more preferably from 0.5 to 0.5% of the EVOH resin. 15 mol%, especially 1-10 mol% is preferable.

  Further, the EVOH resin (A) used in the present invention may be “post-modified” such as urethanization, acetalization, cyanoethylation, oxyalkyleneation and the like.

  Further, the EVOH resin (A) used in the present invention may be a mixture with other different EVOH resins. Examples of such other EVOH resins include those having different contents of ethylene structural units, saponification degree. Can be used, those having different degrees of polymerization, those having different copolymerization components, and the like.

[Fatty acid amide (B)]
The EVOH resin composition of the present invention is a resin composition containing a fatty acid amide (B), and the fatty acid amide (B) is usually contained in an amount of 1 to 500 ppm on a weight basis with respect to the whole EVOH resin composition. The content of the fatty acid amide (B) is preferably 10 to 400 ppm, particularly preferably 30 to 350 ppm. If the amount is too large, the thermal stability may be hindered. If the amount is too small, the moldability of the EVOH resin composition may be impaired.

  The EVOH resin composition serving as a reference for the content ratio of the fatty acid amide (B) contains the fatty acid amide (B) or various additives blended as necessary together with the fatty acid amide (B). EVOH resin composition as a final product.

Examples of the fatty acid amide (B) used in the present invention include saturated higher fatty acid amides such as lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, oleic acid amide; oleic acid amide, Elca And higher fatty acid amides such as unsaturated higher fatty acid amides such as acid amides, bis higher fatty acid amides such as ethylene bis stearic acid amide, ethylene bis oleic acid amide, ethylene bis erucic acid amide and ethylene bis lauric acid amide. These may be used alone or in combination of two or more. In the compound used for the fatty acid amide (B), from the viewpoint of extrusion stability and market availability, the number of carbon atoms in one molecule of the fatty acid amide (B) is usually 12 to 25 carbon atoms, preferably 12 carbon atoms. It is -23, Most preferably, it is C15-20. Moreover, in the said fatty acid amide (B), the valence of the said higher fatty acid is 1-5 valence normally from a viewpoint of extrusion stability and market availability, Preferably it is 1-3 valence, Most preferably, it is 1-2. Value. In this case, the valence means the number of fatty acid-derived structures in one molecule of the fatty acid amide (B). For example, when bis-stearic acid amide is used as the fatty acid amide (B), the fatty acid molecule having 18 carbon atoms. Since the structure derived from is possessed by 2 in one molecule, it is “an amide of a fatty acid having 18 carbon atoms, and the valence of the fatty acid is divalent”.
Among these, preferably a fatty acid amide having 12 to 25 carbon atoms, more preferably a fatty acid amide having 12 to 25 carbon atoms, and a fatty acid amide having a valence of 1 to 5 fatty acids.

  The form of the fatty acid amide (B) is, for example, solid (powder, fine powder, flakes, etc.), semi-solid, liquid, paste, solution, emulsion (water dispersion), etc. Those having the properties of Of these, powder is preferable. The particle size of the powdered fatty acid amide (B) is usually 0.1 to 100 μm, preferably 1 to 75 μm, particularly preferably 5 to 50 μm.

The content of the fatty acid amide (B) in the EVOH resin composition of the present invention can be measured, for example, by the following method.
<Measurement method of content of fatty acid amide (B)>
When the fatty acid amide (B) is attached to the EVOH resin pellet surface, the added amount of the fatty acid amide (B) can be regarded as the content. When fatty acid amide (B) is contained in the EVOH resin composition, the total nitrogen amount in the EVOH resin composition is measured using a trace total nitrogen analyzer and converted to the fatty acid amide (B) content. The content of the fatty acid amide (B) in the EVOH resin composition can be measured.

[Iron compound (C)]
The present invention is characterized in that it contains EVOH resin (A), fatty acid amide (B) and iron compound (C), and the compounding amount of iron compound (C) is a specific trace amount. By adopting such a configuration, the present inventors have found that the resulting resin composition has ultraviolet absorbing ability, is excellent in thermal stability, and coloring is suppressed.

  Such an iron compound (C) is present in the EVOH resin composition, for example, as an oxide, hydroxide, chloride, or iron salt, in an ionized state, or in a resin or other ligand. It may exist in the state of the complex by interaction with. Examples of the oxide include ferric oxide, iron tetroxide, and iron oxide. Examples of the chloride include ferrous chloride and ferric chloride. Examples of the hydroxide include ferrous hydroxide and ferric hydroxide. Examples of the iron salt include inorganic salts such as iron phosphate and iron sulfate, and organic salts such as carboxylic acid (such as acetic acid, butyric acid, and stearic acid) iron.

  From the viewpoint of dispersibility in the EVOH resin composition, the iron compound (C) is preferably water-soluble. Moreover, the molecular weight is 100-10000 normally from a viewpoint of dispersibility and productivity, Preferably it is 100-1000, Most preferably, it is 100-500.

The EVOH resin composition of the present invention is characterized in that the content of the iron compound (C) is 0.01 to 5 ppm in terms of metal per weight of the EVOH resin composition. The content of the iron compound is preferably 0.05 to 3 ppm, particularly preferably 0.08 to 1 ppm.
If the content of the iron compound is too small, the ultraviolet absorption ability tends to decrease, and conversely if it is too large, the molded product tends to be colored.

  Here, the content of the iron compound (C) is determined by demineralizing 0.5 g of the resin composition in an infrared heating furnace (650 ° C. for 1 hour in an oxygen stream) and then dissolving the remaining ash with acid. It can be determined by measuring the content as a sample solution by ICP-MS (manufactured by Agilent Technologies, 7500ce type; standard addition method).

  The content of the fatty acid amide (B) and the metal equivalent content of the iron compound (C) in the EVOH resin composition of the present invention are the content of the fatty acid amide (B) / the metal equivalent content of the iron compound (C). The weight ratio is usually 100 to 50000, preferably 300 to 10000, particularly preferably 500 to 8000, and particularly preferably 1000 to 5000. When this value is too large, the thermal stability tends to decrease, and when it is too small, the molded product tends to be colored.

[Other thermoplastic resins]
The EVOH resin composition of the present invention contains a thermoplastic resin other than the EVOH resin in a range that does not impair the effects of the present invention (for example, usually 30% by weight or less, preferably 20% by weight or less, particularly preferably 10% by weight of the resin composition). % By weight or less).
As other thermoplastic resins, known thermoplastic resins can be used. For example, specifically, polyamide resin, polyolefin resin, polyester resin, polystyrene resin, polyvinyl chloride resin, polycarbonate resin, polyacrylic resin, ionomer, ethylene-acrylic acid copolymer, ethylene- Acrylic acid ester copolymer, ethylene-methacrylic acid copolymer, ethylene-methacrylic acid ester copolymer, polyvinylidene chloride, vinyl ester resin, polyester elastomer, polyurethane elastomer, chlorinated polyethylene, chlorinated polypropylene, etc. .

[Other ingredients]
In addition, the EVOH resin composition of the present invention may contain a compounding agent that is generally blended with the EVOH resin as long as the effects of the present invention are not impaired. For example, inorganic double salts (such as hydrotalcite), plasticizers (such as aliphatic polyhydric alcohols such as ethylene glycol, glycerin and hexanediol), oxygen absorbers [inorganics such as aluminum powder, potassium sulfite, and photocatalytic titanium oxide Oxygen absorbers; ascorbic acid, further fatty acid esters and metal salts thereof, hydroquinone, gallic acid, polyhydric phenols such as hydroxyl group-containing phenolaldehyde resin, bis-salicylaldehyde-imine cobalt, tetraethylenepentamine cobalt, cobalt- Coordinated conjugates of nitrogen-containing compounds such as Schiff base complexes, porphyrins, macrocyclic polyamine complexes, and polyethyleneimine-cobalt complexes with transition metals other than iron, terpene compounds, reactants of amino acids and hydroxyl group-containing reducing substances , Triphenylmethyl compound Organic compound oxygen absorbers such as: Coordination conjugate of nitrogen-containing resin and transition metal other than iron (for example, combination of MXD nylon and cobalt), blend of tertiary hydrogen-containing resin and transition metal other than iron ( For example, a combination of polypropylene and cobalt), a blend of a carbon-carbon unsaturated bond-containing resin and a transition metal other than iron (for example, a combination of polybutadiene and cobalt), a photo-oxidative decay resin (for example, polyketone), an anthraquinone polymer (for example, (Polyvinylanthraquinone), etc., and polymer compounds such as those obtained by adding a photoinitiator (benzophenone, etc.), a peroxide scavenger (commercial antioxidant, etc.) or a deodorant (activated carbon, etc.) to these compounds. Oxygen absorber], heat stabilizer, light stabilizer, ultraviolet absorber, colorant, antistatic agent, surfactant (except for those used as a lubricant), anti-oxidant Agents, anti-blocking agents, may be blended such as fillers (e.g. inorganic fillers and the like). These compounds can be used alone or in combination of two or more.

[Method for Producing EVOH Resin Composition]
Examples of the method for producing the EVOH resin composition of the present invention include known methods such as a dry blend method, a melt mixing method, a solution mixing method, and an impregnation method, and these can be arbitrarily combined.
Examples of the dry blend method include (i) a method of dry blending EVOH resin (A) pellets, fatty acid amide (B) and iron compound (C) using a tumbler or the like.
Examples of the melt mixing method include (ii) a method of melt-kneading a dry blend product of EVOH resin (A) pellets, fatty acid amide (B) and iron compound (C) to obtain pellets and molded products, etc. (iii) ) A method in which a fatty acid amide (B) or an iron compound (C) is added to a molten EVOH resin (A) and melt-kneaded to obtain pellets or molded products.

As the solution mixing method, for example, (iv) a solution is prepared using commercially available EVOH resin (A) pellets, and the fatty acid amide (B) and / or iron compound (C) is blended therein, and then solidified and molded. In the method of pelletizing, solid-liquid separation and drying, and (v) EVOH resin (A) in the production process, the fatty acid amide (B) and / or the EVOH resin (A) in a uniform solution (water / alcohol solution, etc.) Alternatively, a method of containing an iron compound (C), solidifying and pelletizing, solid-liquid separation, and drying may be used.
As the impregnation method, for example, (vi) EVOH resin (A) pellets are brought into contact with an aqueous solution containing fatty acid amide (B) and / or iron compound (C), and fatty acid amide ( Examples thereof include a method of drying after containing B) and / or the iron compound (C).

  As another method, (vii) driving a gear pump by transporting a methanol solution of EVOH resin (A) containing a non-oxidizing acid (for example, hydrochloric acid or acetic acid) at a high concentration with a gear pump or the like. A small amount of iron compound is eluted from a part of stainless steel, and a small amount of iron compound (C) is blended with EVOH resin (A). EVOH resin (A) pellets having EVOH resin (A) and iron compound (C) are obtained from a methanol solution of EVOH resin (A) after such treatment, and such iron compound (C) -containing EVOH resin (A) pellets and boron The compound (B) is dry blended and / or melt-kneaded to obtain pellets, or the iron compound (C) -containing EVOH resin (A) pellets are impregnated with the boron compound (B) and dried. The method of obtaining a pellet by doing is mentioned.

  In the present invention, the above different methods can be combined. Among them, the melt mixing method is preferable, and the methods (ii) and (vii) are particularly preferable in terms of obtaining a resin composition with more remarkable productivity and effects of the present invention.

  In addition, the shape of the EVOH resin composition pellet of this invention obtained by each said method and the EVOH resin (A) pellet used by each method is arbitrary. For example, there are a spherical shape, an oval shape, a cylindrical shape, a cubic shape, a rectangular parallelepiped shape, etc., but it is usually an oval shape or a cylindrical shape, and the size thereof is an oval from the viewpoint of convenience when used as a molding material later. In the case of the shape, the minor axis is usually 1 to 10 mm, preferably 2 to 6 mm, more preferably 2.5 to 5.5 mm, and the major axis is usually 1.5 to 30 mm, preferably 3 to 20, more preferably. Is 3.5 to 10 mm. In the case of a cylindrical shape, the diameter of the bottom surface is usually 1 to 6 mm, preferably 2 to 5 mm, and the length is usually 1 to 6 mm, preferably 2 to 5 mm.

  Further, as described above, the iron compound (C) used in each of the above methods is preferably an oxide such as ferric oxide, ferric tetroxide, iron suboxide, ferrous chloride, ferric chloride. Chlorides such as iron, hydroxides such as ferrous hydroxide and ferric hydroxide, inorganic salts such as iron phosphate and iron sulfate, and organic salts such as carboxylic acid (acetic acid, butyric acid, stearic acid, etc.) iron And iron salts. In addition, as described above, the iron compound is present in the EVOH resin in the ionized state or the complex state due to the interaction with the resin or other ligand, in addition to the case where it exists as the salt. May be.

Moreover, as an aqueous solution containing the iron compound used in the method (vi) above, an aqueous solution of the iron compound or a solution in which iron ions are eluted by immersing the steel material in water containing various chemicals is used. Can do. In this case, the content (in metal equivalent) of the iron compound in the EVOH resin composition can be controlled by the concentration of the iron compound in the aqueous solution in which the EVOH resin (A) pellets are immersed, the immersion temperature, the immersion time, and the like. Is possible. As said immersion temperature and immersion time, it is 0.5 to 48 hours normally, Preferably it is 1-36 hours, and temperature is 10-40 degreeC normally, Preferably it is 20-35 degreeC.
Such EVOH resin composition pellets are solid-liquid separated by a known method and dried by a known drying method. As such a drying method, various drying methods can be adopted, and static drying, fluidized drying, and combinations thereof can be performed.

  The water content of the EVOH resin composition pellets of the present invention is usually 0.01 to 0.5% by weight, preferably 0.05 to 0.35% by weight, particularly preferably 0.1 to 0.3% by weight. %.

In addition, the moisture content of the EVOH resin composition pellet in the present invention is measured and calculated by the following method.
The weight (W1) before drying of the EVOH resin composition pellet is weighed with an electronic balance, dried in a hot air dryer at 150 ° C. for 5 hours, and the weight (W2) after being allowed to cool for 30 minutes in a desiccator is weighed. Calculated from the following formula.
Water content (% by weight) = [(W1-W2) / W1] × 100

The pellets of the EVOH resin composition thus obtained can be used for melt molding as they are, but a known lubricant is attached to the surface of the pellets in terms of stabilizing the feed property during melt molding. Is also preferable. The 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 esters (higher fatty acid methyl esters, isopropyl esters, butyl esters, octyl esters, etc.) And low molecular weight polyolefins (for example, low molecular weight polyethylene having a molecular weight of about 500 to 10,000, low molecular weight polypropylene, etc., or acid-modified products thereof), higher alcohols, ester oligomers, fluorinated ethylene resins, and the like. The content of such a lubricant is usually 5% by weight or less, preferably 1% by weight or less of the EVOH resin composition.
In addition, the fatty acid amide (C) in this invention can be similarly mix | blended by making it adhere to the pellet surface.

  The EVOH resin composition of the present invention thus obtained is prepared as an EVOH resin composition in various forms such as pellets, powder or liquid, and is provided as a molding material for various molded products. In particular, in the present invention, when provided as a material for melt molding, the effects of the present invention tend to be obtained more efficiently, which is preferable. In addition, the resin composition obtained by mixing resin other than EVOH resin (A) used for the EVOH resin composition of this invention is also contained in the EVOH resin composition of this invention.

  Such a molded product is practically used as a multilayer structure having a layer molded using the EVOH resin composition of the present invention, including a single layer film molded using the EVOH resin composition of the present invention. Can be provided.

[Multilayer structure]
The multilayer structure of the present invention has a layer made of the EVOH resin composition of the present invention. The layer containing the EVOH resin composition of the present invention (hereinafter simply referred to as “EVOH resin composition layer”) is another substrate (hereinafter referred to as “base”) containing a thermoplastic resin other than the EVOH resin composition of the present invention as a main component. The resin used for the material may be abbreviated as “base resin.”) To provide further strength, protect the EVOH resin composition layer from the influence of moisture, etc. Can be granted.

  Examples of the 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) copolymer, and ethylene-α-olefin. Polyethylene resins such as (C4-C20 α-olefin) copolymers, polypropylene resins such as polypropylene and propylene-α-olefin (C4-C20 α-olefin) copolymers, polybutene, polypentene (Unmodified) polyolefin resins such as polycyclic olefin resins (polymers having a cyclic olefin structure in at least one of the main chain and side chain), and these polyolefins are graft-modified with unsaturated carboxylic acids or esters thereof Unsaturated carboxylic acid modified polyolefin resin, etc. Broadly defined polyolefin resins including modified olefin resins, ionomers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-acrylic acid ester copolymers, polyester resins, polyamide resins (copolymerized polyamides) ), Polyvinyl chloride, polyvinylidene chloride, acrylic resins, polystyrene resins, vinyl ester resins, polyester elastomers, polyurethane elastomers, polystyrene elastomers, chlorinated polyethylene, chlorinated polypropylene and other halogenated polyolefins, Examples include aromatic or aliphatic polyketones.

  Among these, polyamide resins, polyolefin resins, polyester resins, and polystyrene resins, which are hydrophobic resins, are preferable, and polyethylene resins, polypropylene resins, polycyclic olefin resins, and unsaturated thereof are more preferable. Polyolefin resins such as carboxylic acid-modified polyolefin resins, and particularly polycyclic olefin resins are preferably used as hydrophobic resins.

  When the EVOH 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 of these are possible. In addition, the EVOH resin composition of the present invention obtained by remelt molding an edge portion or defective product generated in the process of producing the multilayer structure and a thermoplastic resin other than the EVOH resin composition of the present invention When the recycled layer containing the mixture is R, b / R / a, b / R / a / b, b / R / a / R / b, b / a / R / a / b, b / R / a / R / a / R / b or the like is also possible. The number of layers of the multilayer structure is usually 2 to 15, preferably 3 to 10 in total. In the above layer configuration, an adhesive resin layer containing an adhesive resin may be interposed between the respective layers as necessary.

  As the adhesive resin, known resins can be used, and may be appropriately selected according to the type of the thermoplastic resin used for the base resin “b”. A typical example is a modified polyolefin polymer containing a carboxyl group obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to a polyolefin resin by an addition reaction or a graft reaction. Examples of the modified polyolefin-based polymer containing a carboxyl group include maleic anhydride graft-modified polyethylene, maleic anhydride graft-modified polypropylene, maleic anhydride graft-modified ethylene-propylene (block and random) copolymer, and maleic anhydride. Examples thereof include a graft-modified ethylene-ethyl acrylate copolymer, a maleic anhydride graft-modified ethylene-vinyl acetate copolymer, a maleic anhydride-modified polycyclic olefin resin, and a maleic anhydride graft-modified polyolefin resin. And 1 type, or 2 or more types of mixtures chosen from these can be used.

  In the multilayer structure, when an adhesive resin layer is used between the EVOH resin composition layer of the present invention and the base resin layer, the adhesive resin layer is located on both sides of the EVOH resin composition layer, It is preferable to use an adhesive resin having excellent properties.

  The above-mentioned base resin and adhesive resin are plastics as 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 based on the whole resin). Agents, fillers, clays (montmorillonite, etc.), colorants, antioxidants, antistatic agents, lubricants, core materials, antiblocking agents, waxes and the like may be included.

  Lamination | stacking (including the case where an adhesive resin layer is interposed) of the EVOH resin composition layer of this invention and the said base resin layer can be performed by a well-known method. For example, a method of melt extrusion laminating a base resin on a film or sheet of the EVOH resin composition of the present invention, a method of melt extrusion laminating the EVOH resin composition of the present invention on a base resin layer, an EVOH resin composition and a base A method of co-extrusion with a base resin, and an EVOH resin composition (layer) and a base resin (layer) are dry-laminated using a known adhesive such as an organic titanium compound, an isocyanate compound, a polyester compound, or a polyurethane compound. Examples thereof include a method, a method of removing a solvent after coating a solution of an EVOH resin composition on a base resin, and the like. Among these, the co-extrusion method is preferable from the viewpoint of cost and environment.

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

  In addition, you may heat-set next for the purpose of providing dimensional stability after extending | stretching. The heat setting can be carried out by a known means. For example, the stretched film is usually heat-treated at 80 to 180 ° C., preferably 100 to 165 ° C. for about 2 to 600 seconds while keeping the stretched state. In addition, when the multilayer stretched film obtained from the EVOH resin composition of the present invention is used as a shrink film, in order to impart heat shrinkability, the above heat setting is not performed, for example, cold air is applied to the stretched film. It is sufficient to perform a process such as fixing by cooling.

  In some cases, it is also possible to obtain a cup or tray-like multilayer container using the multilayer structure of the present invention. In that case, usually a drawing method is employed, and specific examples include a vacuum forming method, a pressure forming method, a vacuum pressure forming method, a plug assist type vacuum forming method. Further, when a tube or bottle-shaped multilayer container (laminated structure) is obtained from a multilayer parison (a hollow tubular preform before blow), a blow molding method is employed. Specifically, extrusion blow molding methods (double-headed, mold moving, parison shift, rotary, accumulator, horizontal parison, etc.), cold parison blow molding, injection blow molding, biaxial stretching Examples thereof include a blow molding method (extruded cold parison biaxial stretch blow molding method, injection cold parison biaxial stretch blow molding method, injection molding inline biaxial stretch blow molding method, and the like). The obtained laminate is 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. as necessary. Can do.

  The thickness of the multilayer structure (including stretched ones) and the thickness of the EVOH resin composition layer, the base resin layer and the adhesive resin layer constituting the multilayer structure are the layer configuration, the type of base resin, and the adhesion. The thickness of the multilayer structure (including the stretched one) is usually 10 to 5000 μm, preferably 30 to 3000 μm, particularly preferably 50-2000 μm. The EVOH 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 10,000 μm. The adhesive resin layer is usually 0.5 to 250 μm, preferably 1 to 150 μm, particularly preferably 3 to 100 μm.

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

Containers and lids made of bags, cups, trays, tubes, bottles, etc. made of films, sheets, stretched films, and the like obtained as described above are seasonings such as mayonnaise and dressing, miso, etc. It is useful as a container for various packaging materials for fermented foods, fats and oils such as salad oil, beverages, cosmetics, and pharmaceuticals.
In particular, the layer made of the EVOH resin composition of the present invention is particularly useful as a packaging material for foodstuffs, particularly meat such as meat, ham, and winner, where discoloration due to ultraviolet rays is likely to be a problem because of its excellent ultraviolet absorbing ability.

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

[UV absorption capacity]
A water / isopropanol (4/6) solution having a concentration of 5% by weight was prepared using the EVOH resin composition. And the ultraviolet-ray transmittance (wavelength 300nm) of this solution was measured using UV-VIS SPECTROTOPOMETER ("UV-2600" by SHIMAZU). By measuring the UV transmittance of the EVOH resin composition in a uniform solution state, it is possible to evaluate the pure UV transmittance of the resin composition itself. The lower the value, the higher the ultraviolet absorbing ability.

[Coloring]
The EVOH resin composition is thermoformed (210 ° C., melting time 5 minutes, compression time 30 seconds) using a manual hydraulic vacuum heating press (Imoto Seisakusho Co., Ltd., IMC-11FD-A type). A resin plate was obtained. The YI value of the obtained resin plate was measured using a color difference meter (Nippon Denshoku Industries Co., Ltd., SE 6000).

[Thermal stability]
Using a thermogravimetric apparatus (Pyris 1 TGA, manufactured by Perkin Elmer), 5 mg of EVOH resin composition was added in a nitrogen atmosphere: 20 mL / min, temperature rising rate: 10 ° C./min, temperature range: 30 ° C. to 550 ° C. Under these conditions, the temperature when the weight decreased to 95% of the weight before measurement was measured.

<Example 1>
As the EVOH resin (A), an ethylene-vinyl alcohol copolymer having an ethylene structural unit content of 44 mol%, a saponification degree of 99.6 mol%, and an MFR of 12 g / 10 min (210 ° C., load of 2160 g) was used. An acetic acid aqueous solution was blended with the methanol solution of EVOH resin (resin concentration 36% by weight) so that acetic acid was 1.5 parts with respect to 100 parts of EVOH resin. The methanol solution was transported by a gear pump, extruded into water from a circular die, turned into a strand, and cut to produce a cylindrical pellet.

  The obtained pellets were brought into contact with an acetic acid aqueous solution (acetic acid concentration: 2200 ppm) at a bath ratio of 2.5 at 35 ° C. for 3 hours, and then dried at 100 ° C. for 36 hours in a nitrogen stream to contain ethylene structural units. EVOH resin pellets in an amount of 44 mol%, a saponification degree of 99.6 mol%, and an MFR of 12 g / 10 min (210 ° C., load of 2160 g) were obtained.

  0.5 g of the sample obtained by pulverizing the EVOH resin pellets obtained was incinerated in an infrared heating furnace (650 ° C. for 1 hour in an oxygen stream), the ash was dissolved in acid, and the volume was adjusted with pure water to obtain a sample solution. did. This solution was measured by the standard addition method using the following ICP-MS (ICP mass spectrometer 7500ce type manufactured by Agilent Technologies), and the iron compound (C) content (metal conversion) per unit weight of EVOH resin pellets was measured. It was measured. The measurement results are shown in Table 1.

100 parts of the EVOH resin pellets obtained above and 0.03 part of ethylene bis-stearic acid amide (manufactured by NOF Corporation, “Alflow H-50F-P”) as the fatty acid amide (B) Lavender Co.) preheated at 210 ° C. for 5 minutes and then melt-kneaded for 5 minutes. The obtained kneaded product was cooled and then pulverized to obtain an EVOH resin composition.
The EVOH resin composition was evaluated as described above. The results are shown in Table 1.

<Comparative Example 1>
100 parts of EVOH resin pellets used in Example 1, 0.03 part of ethylene bis-stearic acid amide (manufactured by NOF Corporation, "Alflow H-50F-P") as fatty acid amide (B), iron compound (C ) As an iron (III) phosphate n hydrate (manufactured by Wako Pure Chemical Industries, Ltd., 230 ° C., loss on drying 20.9% by weight), 0.0034 parts, 210 on a plastograph (manufactured by Brabender) After preheating at 5 ° C. for 5 minutes, the mixture was melt-kneaded for 5 minutes, and the obtained kneaded product was cooled and then pulverized to obtain an EVOH resin composition. Evaluation was similarly performed about the obtained EVOH resin composition. The results are shown in Table 1.

<Comparative Example 2>
An EVOH resin composition was obtained in the same manner as in Example 1 except that ethylene bis stearamide was not blended. Evaluation was similarly performed about the obtained EVOH resin composition. The results are shown in Table 1.

<Comparative Example 3>
In Comparative Example 1, an EVOH resin composition was obtained in the same manner except that ethylene bis stearamide was not blended. Evaluation was similarly performed about the obtained EVOH resin composition. The results are shown in Table 1.

  It can be seen from the Comparative Example 2 and Comparative Example 3 products that had an iron compound and did not contain a fatty acid amide that the ultraviolet absorbing ability was improved in proportion to the amount of the iron compound, and the thermal stability was improved. In addition, when a fatty acid amide containing 10 ppm of an iron compound is used together as in the case of Comparative Example 1, good ultraviolet absorption ability is obtained and the thermal stability is equally good, but Comparative Example 3 in which no fatty acid amide is used in combination. It can be seen that the YI value is improved compared to the above, and coloring occurs.

On the other hand, in the product of Example 1 using the resin composition of the present invention, although the iron compound is a very small amount of 0.1 ppm, the ultraviolet absorbing ability is equivalent to that of Comparative Example 1, and the coloring is suppressed. , Improved thermal stability.
In Comparative Example 2 products and Comparative Example 3 products not containing fatty acid amide (B), although the thermal stability tends to decrease when the blending amount of the iron compound (C) decreases, the fatty acid amide (B) In the contained Example 1, compared with the comparative example 1 which is not used in combination, even if the blending amount of the iron compound (C) is lowered, the thermal stability is not impaired, but rather an unexpected effect of improving is obtained. It can be seen that such an effect can be obtained only by using the fatty acid amide (B) in combination with a trace amount of iron.

  The EVOH resin composition of the present invention has an ultraviolet absorbing ability without blending a general ultraviolet absorber, has excellent thermal stability, and suppresses coloring, so that in addition to various foods, mayonnaise, dressing Etc., fermented foods such as miso, fat and oil foods such as salad oil, beverages, cosmetics, pharmaceuticals, and various other packaging materials.

Claims (5)

  An ethylene-vinyl alcohol copolymer composition containing an ethylene-vinyl alcohol copolymer (A), a fatty acid amide (B), and an iron compound (C), wherein the content of the iron compound (C) is ethylene -An ethylene-vinyl alcohol copolymer composition, which is 0.01 to 5 ppm in terms of metal per weight of the vinyl alcohol copolymer composition.   2. The ethylene-vinyl alcohol copolymer composition according to claim 1, wherein the content of the fatty acid amide (B) is 1 to 500 ppm per weight of the ethylene-vinyl alcohol copolymer composition.   The content of the fatty acid amide (B) and the metal-converted content of the iron compound (C) are 100 to 100 in a weight ratio represented by the content of the fatty acid amide (B) / the metal-converted content of the iron compound (C). The ethylene-vinyl alcohol copolymer composition according to claim 1 or 2, wherein the composition is 50000.   The pellet which consists of an ethylene-vinyl alcohol-type copolymer composition of any one of the said Claims 1-3.   The multilayer structure containing the layer which consists of an ethylene-vinyl alcohol-type copolymer composition of any one of Claims 1-3.