resin composition

Abstract

To provide a resin composition that has reduced tendency to rise in viscosity with time while being heated.SOLUTION: A resin composition comprises an ethylene-vinyl alcoholic copolymer (A), and a nitrogen-containing compound (B). The content of the nitrogen-containing compound (B) is less than 9 wt.% relative to the total amount of the ethylene-vinyl alcoholic copolymer (A) and the nitrogen-containing compound (B)SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition, and more particularly to a resin composition that is inhibited from increasing in viscosity over time when heated. [Background technology]

[0002] Ethylene-vinyl alcohol copolymers (hereinafter sometimes referred to as "EVOH") have very strong intermolecular forces due to hydrogen bonds between hydroxyl groups present in the polymer side chains. As a result, they are highly crystalline, and the intermolecular forces are strong even in the amorphous parts, so films made from EVOH are difficult for gas molecules to pass through, exhibiting excellent gas barrier properties.

[0003] However, because EVOH has relatively active hydroxyl groups in its molecules, oxidation and crosslinking reactions occur in the high-temperature molten state even inside an extruder with almost no oxygen, making it prone to thickening over time and making stable processing difficult.

[0004] To solve this problem, for example, Patent Document 1 discloses a resin composition comprising (A) a saponified ethylene-vinyl acetate copolymer having an ethylene content of 20 to 60 mol% and a degree of saponification of 90 mol% or more, acetic acid (B), magnesium acetate, and / or calcium acetate (C), wherein the content of (B) is 0.05 parts by weight or less per 100 parts by weight of (A), and the content of (C) is 0.001 to 0.02 parts by weight, calculated as metal, per 100 parts by weight of (A). Patent Document 1 also discloses that use of this resin composition results in excellent long-run moldability during melt molding, molded products with fewer fisheyes, streaks, and discoloration, and excellent appearance. Furthermore, when the molded products are formed into laminates, odor is reduced, and the laminates also have excellent interlayer adhesion even after secondary processing such as stretching and deep drawing. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-106592 Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, there has been a trend toward more sophisticated molding equipment due to the diversification of feedblock and die shapes in molding equipment, and various demands for higher functionality, such as thinner multilayer structures and an increase in the number of layers in final products.However, in molding equipment that has become more complex due to this higher functionality, there is a tendency for deteriorated resin to get mixed into the final product, resulting in products that do not meet the acceptance standards and a decrease in productivity (long-run moldability). The technology disclosed in Patent Document 1 is excellent in long-run moldability during melt molding. However, in molding equipment that has become more complex due to its high functionality, the long-run moldability is insufficient due to the contamination of the deteriorated resin into the final product, and further improvement in long-run moldability is required.

[0007] The present inventors focused on resin retention, which is unavoidable due to the structure of the molding machine, and speculated that such retention causes resin degradation products. Therefore, the present invention provides a resin composition in which the increase in viscosity over time during heating, which is a cause of retention, is suppressed, in order to prevent the generation of such resin degradation products. [Means for solving the problem]

[0008] However, in view of these circumstances, the present inventors have conducted extensive research and have found that by adding a specific amount of a nitrogen-containing compound to EVOH, a resin composition can be obtained in which the increase in viscosity over time when heated is suppressed, and have thus completed the present invention.

[0009] That is, the present invention provides the following [1] to [6]. [1] A resin composition comprising an EVOH (A) and a nitrogen-containing compound (B), wherein the content of the nitrogen-containing compound (B) is less than 9% by weight based on the total amount of the EVOH (A) and the nitrogen-containing compound (B). [2] The resin composition according to [1], wherein the nitrogen-containing compound (B) contains a primary amino group and / or a secondary amino group. [3] The resin composition according to [1] or [2], wherein the nitrogen-containing compound (B) has a molecular weight of 280 or less. [4] The resin composition according to any one of [1] to [3], wherein the nitrogen-containing compound (B) has an amine equivalent defined by the following formula of less than 225 g / eq. Formula) Amine equivalent (g / eq) = molecular weight of nitrogen-containing compound (B) / number of primary amino groups (-NH2) and secondary amino groups (-NH-) present in nitrogen-containing compound (B) [5] The resin composition according to any one of [1] to [4], wherein the melting point of the nitrogen-containing compound (B) is 70 to 230°C. [6] The resin composition according to [1], wherein the nitrogen-containing compound (B) is 2-imidazolidinone. [Effects of the Invention]

[0010] The resin composition of the present invention is inhibited from increasing in viscosity over time during melt molding and is excellent in long-run moldability. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described in detail below, but these are examples of preferred embodiments. In the present invention, "x and / or y (x and y are any constitutions or components)" means three combinations: x only, y only, and x and y.

[0012] A resin composition according to one embodiment of the present invention (hereinafter referred to as "the resin composition") contains EVOH (A) and a nitrogen-containing compound (B), and the content of the nitrogen-containing compound (B) is less than 9% by weight based on the total amount of the EVOH (A) and the nitrogen-containing compound (B). Each component will be described below.

[0013] [EVOH(A)] The EVOH (A) used in the present resin composition is a water-insoluble thermoplastic resin obtained by saponifying an ethylene-vinyl ester copolymer, which is a copolymer of ethylene and a vinyl ester monomer. For economic reasons, vinyl acetate is generally used as the vinyl ester monomer.

[0014] The copolymerization of ethylene with a vinyl ester monomer can be carried out by any known polymerization method, such as solution polymerization, suspension polymerization, emulsion polymerization, etc., and solution polymerization using methanol as a solvent is generally used. The saponification of the obtained ethylene-vinyl ester copolymer can also be carried out by a known method.

[0015] The EVOH (A) produced in this manner is mainly composed of ethylene structural units and vinyl alcohol structural units, and when the degree of saponification is less than 100 mol %, it contains a small amount of vinyl ester structural units remaining as unsaponified portions.

[0016] As the vinyl ester monomer, vinyl acetate is generally used as described above from the standpoint of economy and the efficiency of treating impurities during production. Examples of vinyl ester monomers other than vinyl acetate include aliphatic vinyl esters such as vinyl formate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, and vinyl versatate, and aromatic vinyl esters such as vinyl benzoate. These may be used alone or in combination of two or more. Of these, aliphatic vinyl esters having 3 to 20 carbon atoms are preferred, more preferably 4 to 10 carbon atoms, and particularly preferably 4 to 7 carbon atoms.

[0017] The content of ethylene structural units in the EVOH (A), measured according to ISO 14663, is usually 20 to 60 mol%, preferably 25 to 50 mol%, and particularly preferably 27 to 35 mol%. If this content is too low, the gas barrier properties and melt moldability under high humidity conditions tend to decrease, while if it is too high, the gas barrier properties tend to decrease. The content of ethylene structural units can be controlled by the ethylene pressure when copolymerizing the vinyl ester monomer with ethylene.

[0018] The saponification degree of the EVOH (A), measured in accordance with JIS K6726 (wherein the EVOH (A) is a solution uniformly dissolved in a water / methanol solvent), is usually 90 to 100 mol%, preferably 95 to 100 mol%, and particularly preferably 99 to 100 mol%. If the saponification degree is too low, the gas barrier properties tend to decrease. The saponification degree can be controlled by the amount, temperature, time, etc. of the saponification catalyst (usually an alkaline catalyst such as sodium hydroxide) used when saponifying the ethylene-vinyl ester copolymer.

[0019] The melt flow rate (MFR) of the EVOH (A) (210°C, load 2160 g) is usually 0.5 to 100 g / 10 min, preferably 1 to 50 g / 10 min, and particularly preferably 3 to 35 g / 10 min. If the MFR is too high, film-forming properties tend to become unstable, whereas if it is too low, the viscosity tends to become too high, making melt extrusion difficult.

[0020] The MFR is an index of the degree of polymerization of EVOH (A), and can be adjusted by the amount of polymerization initiator and the amount of solvent used when copolymerizing ethylene with a vinyl ester monomer.

[0021] Furthermore, EVOH (A) may further contain structural units derived from the comonomers shown below within a range that does not impair the effects of the present invention (for example, 10 mol % or less of EVOH (A)).

[0022] Examples of the comonomer include olefins such as propylene, 1-butene, and isobutene; hydroxyl group-containing α-olefins such as 3-buten-1-ol, 3-butene-1,2-diol, 4-penten-1-ol, and 5-hexene-1,2-diol, and derivatives thereof such as esters and acylation products; hydroxyalkylvinylidenes such as 2-methylenepropane-1,3-diol and 3-methylenepentane-1,5-diol; 1,3-diacetoxy-2-methylenepropane, 1,3-dipropionyloxy-2-methylenepropane, and 1,3-dibutyryloxy. hydroxyalkylvinylidene diacetates such as 2-methylenepropane; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, (anhydrous) phthalic acid, (anhydrous) maleic acid, (anhydrous) itaconic acid, or their salts or mono- or di-alkyl esters in which the alkyl group has 1 to 18 carbon atoms; acrylamide, N-alkylacrylamide in which the alkyl group has 1 to 18 carbon atoms, N,N-dimethylacrylamide, 2-acrylamidopropanesulfonic acid or its salts, acrylamidopropyldimethylamine or its acid salts or its quaternary salts, etc. Acrylamides; methacrylamide, N-alkylmethacrylamides in which the alkyl group has 1 to 18 carbon atoms, N,N-dimethylmethacrylamide, 2-methacrylamidopropanesulfonic acid or its salt, methacrylamidepropyldimethylamine or its acid salt or its quaternary salt; N-vinylamides such as N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide; vinyl cyanides such as acrylonitrile and methacrylonitrile; alkyl vinyl ethers in which the alkyl group has 1 to 18 carbon atoms, hydrochlorides vinyl ethers such as alkoxyalkyl vinyl ether and alkoxyalkyl vinyl ether; halogenated vinyl compounds such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride and vinyl bromide; vinyl silanes such as trimethoxyvinylsilane; halogenated allyl compounds such as allyl acetate and allyl chloride; allyl alcohols such as allyl alcohol and dimethoxyallyl alcohol; and comonomers such as trimethyl-(3-acrylamido-3-dimethylpropyl)-ammonium chloride and acrylamido-2-methylpropanesulfonic acid.These may be used alone or in combination of two or more.

[0023] In particular, EVOH copolymerized with hydroxy group-containing α-olefins, i.e., EVOH having hydroxy groups in the side chain, is preferred because it has good secondary formability while maintaining gas barrier properties, more preferred is EVOH having primary hydroxy groups in the side chain, and particularly preferred is EVOH having a 1,2-diol structure in the side chain.

[0024] As the EVOH having a primary hydroxyl group in the side chain, the content of structural units derived from a monomer having the primary hydroxyl group is preferably usually 0.1 to 20 mol %, more preferably 0.5 to 15 mol %, and particularly preferably 1 to 10 mol % of the EVOH.

[0025] The EVOH (A) may also be "post-modified" such as urethanized, acetalized, cyanoethylated, or oxyalkylened.

[0026] Furthermore, the EVOH (A) used in the present resin composition may be a mixture of two or more types of EVOH, for example, EVOHs with different degrees of saponification, different degrees of polymerization, or different copolymerization components.

[0027] EVOH (A) is preferably the main component of the resin composition, where the content of the main component is 60% 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 of the resin composition.

[0028] [Nitrogen-containing compound (B)] The nitrogen-containing compound (B) used in the resin composition is not particularly limited as long as it contains a nitrogen atom in its structure, and may be an amino compound containing at least one of a primary amino group (-NH), a secondary amino group (-NH-), a tertiary amino group (see general formula (1) below), and a quaternary amino group (see general formula (2) below). Amino compounds containing a primary amino group (-NH) and / or a secondary amino group (-NH-) are particularly preferred. By including a primary amino group (-NH) and / or a secondary amino group (-NH-), the effect of inhibiting thickening over time provided by the nitrogen-containing compound (B) tends to be further enhanced.

[0029] [ka]

[0030] The molecular weight of the nitrogen-containing compound (B) is not particularly limited, but the molecular weight is preferably 280 or less, more preferably 230 or less, particularly preferably 150 or less, and especially preferably 100 or less. When the molecular weight is 280 or less, thickening over time during heating tends to be suppressed even with a small amount added. The lower limit of the molecular weight is not particularly limited, but the molecular weight is preferably 17 or more, more preferably 30 or more, particularly preferably 40 or more, and especially preferably 50 or more.

[0031] The amine equivalent of the nitrogen-containing compound (B) is not particularly limited, but is preferably less than 225 g / eq, more preferably 200 g / eq or less, particularly preferably 150 g / eq or less, and especially preferably 100 g / eq or less. An amine equivalent of less than 225 g / eq tends to suppress thickening over time during heating with a small amount of addition. The lower limit of the amine equivalent is not particularly limited, but is preferably 10 g / eq or more, more preferably 20 g / eq or more, particularly preferably 30 g / eq or more, and especially preferably 40 g / eq or more. When the amine equivalent is 10 g / eq or less, the compound is often not solid near room temperature and tends to be difficult to handle. The amine equivalent is the weight of the nitrogen-containing compound (B) containing one equivalent of an amino group, and can be calculated using the following formula: Formula) Amine equivalent (g / eq) = molecular weight of nitrogen-containing compound (B) / number of primary amino groups (-NH2) and secondary amino groups (-NH-) present in nitrogen-containing compound (B)

[0032] The melting point of the nitrogen-containing compound (B) is not particularly limited, but the lower limit of the melting point is preferably 70° C., more preferably 80° C., particularly preferably 90° C., and especially preferably 100° C. The upper limit of the melting point is preferably 230° C., more preferably 210° C., particularly preferably 190° C., and especially preferably 170° C. When the melting point is within the above range, the nitrogen-containing compound (B) is easy to handle and tends to exhibit excellent effects since it melts at the melt-molding temperature of EVOH (A).

[0033] Specific examples of the nitrogen-containing compound (B) include inorganic amino compounds and organic amino compounds, which may be used alone or in combination of two or more.

[0034] Examples of the inorganic amino compounds include hydroxylamine, chloramine, and ammonia.

[0035] Examples of the organic amino compound include aliphatic amines such as methanolamine, ethanolamine, dimethylamine, diethylamine, isopropylamine, butylamine, dicyanodiamide, ethylenediamine, propylenediamine, diethylenetriamine, 1,2-diaminopropane, 1,3-diaminopropane, triethylenetetramine, tetraethylenepentamine, iminobispropylamine, hexamethylenediamine, 3-azahexane-1,6-diamine, 2-acrylamido-2-methylpropanesulfonic acid, and 4,7-diazadecane-1,10-diamine; heterocyclic amines such as proline, hydroxyproline, ethyleneimine, morpholine, α-amino-ε-caprolactam, and acetaldehyde ammonia; heterocyclic aromatic amines such as amine, 2-amino-4,5-dicyanoimidazole, 2-undecylimidazole, acetoguanamine, pyrrolidine, piperidine, and piperazine; compounds having a urea bond such as urea, thiourea, methylurea, ethylurea, dimethylurea, diethylurea, ethyleneurea (2-imidazolidinone), guanylurea, guanylthiourea, azodicarbonamide, glycolyl urea, and acetyl urea; compounds having an amide bond such as formamide, acetamide, benzamide, oxamide, oxamic acid, succinamide, and malonamide; and compounds having an imide bond such as succinimide, phthalimide, maleimide, 1-methylol-5,5-dimethylhydantoin, and isocyanuric acid.

[0036] Among these nitrogen-containing compounds (B), organic amino compounds are preferred from the viewpoint of suppressing thickening over time, more preferably heterocyclic aromatic amines and compounds having a urea bond, particularly preferably 2-undecylimidazole and ethyleneurea (2-imidazolidinone), and particularly preferably ethyleneurea (2-imidazolidinone).

[0037] The content of the nitrogen-containing compound (B) in the resin composition is less than 9% by weight, preferably 7% by weight or less, more preferably 5% by weight or less, particularly preferably 3% by weight or less, and especially preferably 1% by weight or less, based on the total amount of the EVOH (A) and the nitrogen-containing compound (B). If the content of the nitrogen-containing compound (B) exceeds the above-mentioned value, the effect of suppressing thickening during melt molding cannot be obtained. Furthermore, if the content of the nitrogen-containing compound (B) is 9% by weight or more, a noticeable odor occurs during molding, which tends to be undesirable for a melt-molded product.

[0038] The lower limit of the content of the nitrogen-containing compound (B) is not particularly limited, but is preferably 0.000001% by weight or more, more preferably 0.00001% by weight or more, particularly preferably 0.0001% by weight or more, and particularly preferably 0.001% by weight or more, based on the total amount of the EVOH (A) and the nitrogen-containing compound (B). If the content of the nitrogen-containing compound (B) is less than the above-mentioned value, the effect of suppressing thickening during melt molding tends to be insufficient.

[0039] By combining EVOH (A) with a specific amount of nitrogen-containing compound (B), this resin composition can surprisingly suppress the increase in viscosity of EVOH (A) over time during molding processing, thereby improving long-run moldability. This is presumably because the nitrogen-containing compound (B) captures aldehydes that are generated over time from EVOH (A) during molding processing, thereby suppressing the crosslinking reaction of EVOH (A).

[0040] The present resin composition preferably further contains a boron compound, since this can further enhance the effect of suppressing thickening over time during melt molding.

[0041] [Boron compounds] Examples of the boron compound include boric acid or a metal salt thereof, such as boric acid, calcium borate, cobalt borate, zinc borate (e.g., zinc tetraborate, zinc metaborate), aluminum potassium borate, ammonium borate (e.g., ammonium metaborate, ammonium tetraborate, ammonium pentaborate, ammonium octaborate), cadmium borate (e.g., cadmium orthoborate, cadmium tetraborate), potassium borate (e.g., potassium metaborate, potassium tetraborate, potassium pentaborate, potassium hexaborate, potassium octaborate), silver borate (e.g., silver metaborate, silver tetraborate), copper borate (e.g., cupric borate, copper metaborate, copper tetraborate), sodium borate (e.g., sodium metaborate, sodium diborate, sodium tetraborate, sodium pentaborate, sodium hexaborate), sodium octaborate, etc.), lead borate (lead metaborate, lead hexaborate, etc.), nickel borate (nickel orthoborate, nickel diborate, nickel tetraborate, nickel octaborate, etc.), barium borate (barium orthoborate, barium metaborate, barium diborate, barium tetraborate, etc.), bismuth borate, magnesium borate (magnesium orthoborate, magnesium diborate, magnesium metaborate, trimagnesium tetraborate, pentamagnesium tetraborate, etc.), manganese borate (manganese borate, manganese metaborate, manganese tetraborate, etc.), lithium borate (lithium metaborate, lithium tetraborate, lithium pentaborate, etc.), as well as borate minerals such as borax, kernite, inyoite, cottite, suianite, and seiberite. These may be used alone or in combination of two or more. Among these, borax, boric acid, and sodium borate (sodium metaborate, sodium diborate, sodium tetraborate, sodium pentaborate, sodium hexaborate, sodium octaborate, etc.) are preferred.

[0042] The content of the boron compound is not particularly limited, but the lower limit of the content is preferably 1 ppm, more preferably 10 ppm, particularly preferably 20 ppm, and especially preferably 50 ppm, calculated as boron relative to EVOH (A). The upper limit of the content is preferably 1000 ppm, more preferably 500 ppm, particularly preferably 300 ppm, and especially preferably 100 ppm, calculated as boron relative to EVOH (A). When the content is within the above range, a synergistic effect with the nitrogen-containing compound can be achieved, further enhancing the effect of improving long-run moldability. The reason why excellent effects are obtained by using a specific amount of boron compound is not clear, but it is presumed that this is because the dischargeability of the resin composition is improved by adjusting the melt viscosity.

[0043] The content of the boron compound in terms of boron can be measured by a known analytical method. For example, the resin composition can be wet decomposed, the volume of which is measured, and the amount of boron can be quantified by inductively coupled plasma atomic emission spectrometry (ICP-AES).

[0044] Furthermore, the present resin composition may contain a thermoplastic resin other than EVOH (A) (for example, various thermoplastic resins such as polyamide, polyester, polyethylene, polypropylene, polystyrene, etc.) within a range that does not impair the effects of the present invention (for example, typically 30% by weight or less of the present resin composition, preferably 20% by weight or less, particularly preferably 10% by weight or less).

[0045] Furthermore, the resin composition may contain, as needed, plasticizers, reinforcing agents, fillers, pigments, dyes, lubricants, antioxidants, antistatic agents, ultraviolet absorbers, heat stabilizers, light stabilizers, surfactants, antibacterial agents, antistatic agents, desiccants, antiblocking agents, flame retardants, crosslinking agents, curing agents, foaming agents, crystal nucleating agents, etc., within the range that does not impair the effects of the invention (for example, 5% by weight or less of the resin composition).

[0046] [Preparation of Resin Composition] The present resin composition can be obtained by mixing EVOH (A) and the nitrogen-containing compound (B) with optional components that are blended as needed.

[0047] The mixing method is not particularly limited, and the components can be mixed by dry blending and then used directly as a resin composition. Generally, however, a method is used in which the components are mixed by a melt mixing method, a solution mixing method, or the like, and then molded into an easily handleable shape such as pellets to prepare a resin composition, and the melt mixing method is preferred from the viewpoint of productivity.

[0048] The melt mixing method typically involves dry blending the components, followed by melting and mixing. Known kneading devices such as kneader-ruders, extruders, mixing rolls, Banbury mixers, and plastomills can be used as mixing devices, but it is generally industrially preferable to use single-screw or twin-screw extruders. It is also preferable to equip the extruder with a vent suction device, a gear pump device, a screen device, or the like, as needed.

[0049] The melt-kneading temperature, as set temperatures for the extruder and die, is usually in the range of 160 to 300° C., preferably 170 to 260° C., and particularly preferably 180 to 240° C. If the temperature is too low, the resin will be in an unmelted state, and the processing state will tend to become unstable, whereas if the temperature is too high, the resin composition will tend to be thermally deteriorated, and the quality of the resulting molded product will tend to decrease.

[0050] The method for adjusting the amount of the nitrogen-containing compound (B) or any optional component added to the resin composition is not particularly limited, and may include a method of adjusting by adding the desired amount, a method of preparing a masterbatch and diluting it, etc. When the masterbatch is diluted, any dilution method may be used, but dry blending is preferred from the viewpoint of productivity.

[0051] In addition to the above-mentioned method, the optional components such as the boron compound may be added during the production of EVOH (A), for example.

[0052] The resin composition thus obtained is typically melt-molded into molded articles such as films, sheets, cups, fibers, etc. Examples of such melt-molding methods include extrusion molding (T-die extrusion, inflation extrusion, blow molding, melt spinning, profile extrusion, etc.) and injection molding. The melt-molding temperature can typically be appropriately selected from the range of 150 to 300°C. The resulting molded articles (films, sheets, cups, fibers, etc.) can also be subjected to secondary processing such as uniaxial or biaxial stretching and vacuum molding.

[0053] Furthermore, the molded article obtained by melt molding using the present resin composition may be a molded article consisting of the present resin composition alone, or may be a molded article consisting of a multilayer structure in which the resin composition is laminated with a substrate such as another resin sheet or film, paper, nonwoven fabric, or metal foil.

[0054] The multilayer structure can be produced by melt-extrusion laminating another substrate onto a film, sheet, etc. formed using the resin composition of the present invention, melt-extrusion laminating the resin composition onto another substrate, co-extruding the resin composition with another substrate, or dry-laminating a film, sheet, etc. formed using the resin composition of the present invention with a layer of another substrate using a known adhesive such as an organic titanium compound, an isocyanate compound, a polyester compound, or a polyurethane compound. [Example]

[0055] The present invention will be explained in more detail below by way of examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention.

[0056] Prior to the examples, the following ingredients were prepared:

[0057] [EVOH(A)] EVOH (A1): Ethylene structural unit content 29 mol%, MFR 8g / 10min (210℃, load 2160g), saponification degree 99.7 mol%, boron compound content (boron equivalent) 0ppm EVOH (A2): Ethylene structural unit content 29 mol%, MFR 3.8 g / 10 min (210°C, load 2160 g), saponification degree 99.6 mol%, boron compound content (boron equivalent) 70 ppm

[0058] <Boron compound content in pellets (boron equivalent)> The content of boron compounds in the EVOH (A) was determined by treating 0.1 g of EVOH (A) pellets with concentrated nitric acid using a microwave decomposition method, diluting the resulting solution with pure water to a fixed volume (0.75 mg / mL), and measuring the content of the boron using an inductively coupled plasma atomic emission spectrometer (ICP-AES) (Agilent Technologies, Model 720-ES). The boron content measured corresponds to the amount of boron derived from boron compounds.

[0059] [Nitrogen-containing compounds (B)] Nitrogen-containing compound (B1): 2-imidazolidinone (Tokyo Chemical Industry Co., Ltd., molecular weight 86, amine equivalent 43 g / eq, melting point 132°C) Nitrogen-containing compound (B2): 2-undecylimidazole (Mitsubishi Chemical Corporation, molecular weight 222, amine equivalent 222 g / eq, melting point 73°C)

[0060] Example 1 A resin composition was prepared by dry blending EVOH (A1) and a nitrogen-containing compound (B1) so that the amount of (B1) was 1.0% by weight based on the total amount of (A1) and (B1).

[0061] <Examples 2 to 9, Comparative Example 1> Resin compositions were prepared in the same manner as in Example 1, except that the types and amounts of the nitrogenated materials were changed as shown in Table 1 below.

[0062] The prepared resin compositions were used to evaluate the viscosity increase suppression rate described below.

[0063] <Evaluation of viscosity increase suppression rate> 55 g of each resin composition was melt-kneaded under the following melt-kneading conditions, and the change in torque value over time was recorded. EVOH (A1) and EVOH (A2) were also melt-kneaded in the same manner as blanks, and the change in torque value over time was recorded. [Melt-mixing conditions] Equipment: Brabender Plastograph Conditions: 240°C, 50 rpm, preheating for 5 minutes, kneading for 180 minutes

[0064] The viscosity increase ratio was calculated from the obtained torque values ​​after 60 minutes and after 180 minutes using the following formula. Thickening ratio = torque value after 180 minutes of measurement / torque value after 60 minutes of measurement Next, the viscosity increase suppression rate was calculated from the calculated viscosity increase ratio of each Example or Comparative Example and the viscosity increase ratio of the blank using the following formula. Thickening suppression rate (%) = [thickening ratio (blank) - thickening ratio (example or comparative example)] / thickening ratio (blank) × 100

[0065] [Table 1]

[0066] The results in Table 1 above show that the resin compositions of Examples 1 to 9, which contain EVOH (A) and a specific amount of nitrogen-containing compound (B), show less increase in viscosity over time and improved long-run moldability compared to blank EVOH (A1) or (A2) which does not contain nitrogen-containing compound (B). Furthermore, it is clear that, among the resin compositions of Examples 1 to 9, the resin compositions of Examples 1 to 6, which used 2-imidazolidinone as the nitrogen-containing compound (B), are particularly excellent in the effect of thickening over time. Furthermore, the resin composition of Comparative Example 1, in which the amount of nitrogen-containing compound (B) added was 9% by weight, was more viscous than blank EVOH (A1) that did not contain nitrogen-containing compound (B), and no thickening suppression effect was obtained. [Industrial Applicability]

[0067] The resin composition of the present invention inhibits thickening over time during melt molding and has excellent long-run moldability, and is therefore particularly useful as a packaging material for various foods as well as seasonings such as mayonnaise and dressings, fermented foods such as miso, oily foods such as salad oil, beverages, cosmetics, pharmaceuticals, etc.

Claims

[Claim 1] A resin composition comprising an ethylene-vinyl alcohol copolymer (A) and a nitrogen-containing compound (B), wherein the content of the ethylene-vinyl alcohol copolymer (A) is 60% by weight or more of the resin composition, the nitrogen-containing compound (B) is 2-undecylimidazole and / or 2-imidazolidinone, and the content of the nitrogen-containing compound (B) is 0.000001% by weight or more and less than 9% by weight based on the total amount of the ethylene-vinyl alcohol copolymer (A) and the nitrogen-containing compound (B).

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