JP7312983B2 - Ethylene-vinyl alcohol resin composition, and molded article and multilayer structure using the same - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Law 1. 1. Publication at a meeting (academic conference) Name of academic conference: 2019 46th Annual Meeting of the Japanese Society of Rheology, date of presentation: May 8, 2019 2. 2. Publication by publication in publications (conference proceedings) Society name: 2019 46th Annual Meeting of the Japan Society of Rheology, Publication name: 2019 46th Annual Meeting of the Japan Society of Rheology, pp. 17-18, publication date: May 8, 2019 Disclosure through electric communication lines (publishing of conference proceedings on the website) Name of society: 68th Annual Meeting of the Society of Polymer Science, Posting address (URL): https://member. spsj. or. jp/convention/spsj2019/index. php? id = 2Pd052 & place_num = 1, publication date: May 14, Reiwa 4. 5. Disclosure by presentation at a meeting (academic society) Name of society: 2019 Annual Meeting of the Rubber Society of Japan, date of presentation: May 23, 2019 6. Released by publishing in publications (lecture abstracts) Society name: Japan Rubber Association 2019 Annual Conference, Publication name: Japan Rubber Association 2019 Annual Conference research presentation abstracts, page 87, date of publication: May 23, 2019 6. Disclosure by presentation at a meeting (conference) Name of society: 68th SPSJ Annual Meeting 2019, date of presentation: May 30, 2019

TECHNICAL FIELD The present invention relates to a resin composition that does not bleed out additives and has good fluidity, and a molded article and a multilayer structure using the same.

Ethylene-vinyl alcohol copolymer (hereinafter sometimes abbreviated as "EVOH") is a crystalline polymer having both excellent gas barrier properties and organic solvent resistance derived from vinyl alcohol units, and melt moldability and water resistance derived from ethylene units, and is applied to a wide range of applications.

Patent Document 1 describes that a resin composition having an ethylene-vinyl alcohol copolymer and an additive comprising a specific hydroxyl group-containing compound can provide a resin molded product having high oxygen barrier properties, a low glass transition temperature, and high flexibility without causing bleeding out.

WO2015/163437

However, the additive used in the invention described in Patent Document 1 is 1,1,1-trimethylolpropane or the like, and these additives contribute to improving the fluidity of EVOH (lowering the melting point), but at the same time, there was a problem that the tensile modulus, yield strength, etc. decreased.

An object of the present invention is to provide an EVOH resin composition that does not cause bleeding out, suppresses a decrease in tensile modulus and yield strength, and has improved resin fluidity.

［式中、Ｒ¹は、それぞれ独立してヒドロキシル基、炭素数１～３のヒドロキシアルキル基、及び炭素数１～３のヒドロキシアルコキシ基からなる群より選択される基であり、Ｒ²は、それぞれ独立して水素原子、炭素数１～３のアルキル基、及び炭素数１～３のアルコキシ基からなる群より選択される基である。］

［式中、Ｒ³とＲ⁴は、それぞれ独立してヒドロキシル基を１つ以上有する炭素数１～２０のアルキル基である。］；
［２］添加剤（Ｂ）の融点が１００℃以上２００℃以下である、［１］のＥＶＯＨ樹脂組成物；
［３］添加剤（Ｂ２）がメタキシレンビス－１２－ヒドロキシステアリン酸アミドである、［１］または［２］のＥＶＯＨ樹脂組成物；
［４］ＥＶＯＨ（Ａ）のエチレン単位含有率が２０～６０モル％である、［１］～［３］のいずれかのＥＶＯＨ樹脂組成物；
［５］［１］～［４］のいずれかのＥＶＯＨ樹脂組成物からなる成形体；
［６］［１］～［４］のいずれかのＥＶＯＨ樹脂組成物からなる層を少なくとも１層含む多層構造体；
を提供することで達成される。 That is, the present invention includes [1] an ethylene-vinyl alcohol copolymer (A) (hereinafter sometimes abbreviated as "EVOH (A)") and an additive (B), wherein the additive (B) is an additive (B1) represented by the following general formula (1) (hereinafter sometimes abbreviated as "additive (B1)") or an additive (B2) represented by the following general formula (2) (hereinafter sometimes abbreviated as "additive (B2)"), and an additive ( An EVOH resin composition in which the content of B) is from 0.01 to 20% by mass.

[In the formula, each R ¹ is a group independently selected from the group consisting of a hydroxyl group, a hydroxyalkyl group having 1 to 3 carbon atoms, and a hydroxyalkoxy group having 1 to 3 carbon atoms, and each R ² is a group independently selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, and an alkoxy group having 1 to 3 carbon atoms. ]

[In the formula, R ³ and R ⁴ are each independently an alkyl group having 1 to 20 carbon atoms and having one or more hydroxyl groups. ];
[2] The EVOH resin composition of [1], wherein the additive (B) has a melting point of 100°C or higher and 200°C or lower;
[3] The EVOH resin composition of [1] or [2], wherein the additive (B2) is meta-xylene bis-12-hydroxystearic acid amide;
[4] The EVOH resin composition of any one of [1] to [3], wherein the ethylene unit content of EVOH (A) is 20 to 60 mol%;
[5] A molded article made of the EVOH resin composition of any one of [1] to [4];
[6] A multilayer structure comprising at least one layer made of the EVOH resin composition of any one of [1] to [4];
This is achieved by providing

According to the present invention, it is possible to provide an EVOH resin composition that does not cause bleeding out, suppresses a decrease in tensile modulus and yield strength, and has improved resin fluidity, as well as a molded article and a multilayer structure using the same.

2 shows the evaluation results of the rheological properties in the molten state of the melt-blended products obtained in Comparative Example 1, Example 2 and Example 4. FIG. 1 shows the measurement results of dynamic viscoelasticity of sample films obtained in Comparative Example 1, Example 1 and Example 2. FIG. 4 shows the measurement results of dynamic viscoelasticity of the sample films obtained in Comparative Example 1, Example 3 and Example 4. FIG. 4 shows the measurement results of the free volume of the sample films obtained in Comparative Example 1 and Examples 1-4.

The EVOH resin composition of the present invention contains EVOH (A) and additive (B), additive (B) is additive (B1) or additive (B2), and the content of additive (B) is 0.01 to 20% by mass.

(EVOH (A))
Since the resin composition of the present invention contains EVOH (A), it exhibits good gas barrier properties. EVOH (A) can usually be obtained by saponifying an ethylene-vinyl ester copolymer. Production and saponification of the ethylene-vinyl ester copolymer can be carried out by known methods. Vinyl esters are typically vinyl acetate, but may also be other fatty acid vinyl esters such as vinyl formate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl pivalate and vinyl versatate.

The ethylene unit content of EVOH (A) is preferably 20 mol % or more, more preferably 25 mol % or more, and even more preferably 33 mol % or more. The ethylene unit content of EVOH (A) is preferably 60 mol % or less, more preferably 55 mol % or less, and even more preferably 50 mol % or less. When the ethylene unit content is 20 mol % or more, the melt moldability tends to be good. On the other hand, when the ethylene unit content is 60 mol % or less, the barrier properties tend to increase. The ethylene unit content of EVOH (A) can be determined by a nuclear magnetic resonance (NMR) method.

The degree of saponification of the vinyl ester component of EVOH (A) is preferably 80 mol% or more, more preferably 90 mol% or more, even more preferably 99 mol% or more. By setting the degree of saponification to 90 mol % or more, it is possible to improve the gas barrier properties of the molded product. The degree of saponification of EVOH (A) may be 100 mol % or less or 99.99 mol % or less. The degree of saponification of EVOH (A) can be calculated by performing ¹ H-NMR measurement and measuring the peak area of hydrogen atoms contained in the vinyl ester structure and the peak area of hydrogen atoms contained in the vinyl alcohol structure.

In addition, EVOH (A) may have units derived from monomers other than ethylene, vinyl esters, and saponified products thereof, as long as the object of the present invention is not hindered. When EVOH (A) has the other monomer unit, the content of the other monomer unit with respect to all structural units of EVOH (A) is preferably 30 mol% or less, more preferably 20 mol% or less, further preferably 10 mol% or less, and particularly preferably 5 mol% or less. Moreover, when EVOH (A) has units derived from the other monomers, the lower limit thereof may be 0.05 mol % or 0.10 mol %. Examples of the other monomers include alkenes such as propylene, butylene, pentene, and hexene; Alkenes having an ester group such as diacyloxy-2-methyl-1-butene, 4-acyloxy-1-pentene, 5-acyloxy-1-pentene, 4,5-diacyloxy-1-pentene, 4-acyloxy-1-hexene, 5-acyloxy-1-hexene, 6-acyloxy-1-hexene, 5,6-diacyloxy-1-hexene, 1,3-diacyloxy-2-methylenepropane or saponification thereof unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, and itaconic acid, or their anhydrides, salts, or mono- or dialkyl esters; nitriles such as acrylonitrile and methacrylonitrile; amides such as acrylamide and methacrylamide; Vinylsilane compounds such as methoxysilane; alkyl vinyl ethers, vinyl ketones, N-vinylpyrrolidone, vinyl chloride, vinylidene chloride and the like.

EVOH (A) may be post-modified EVOH (A) by techniques such as urethanization, acetalization, cyanoethylation and oxyalkylenation.

The melt flow rate (MFR) of EVOH (A) measured in accordance with JIS K 7210:2014 at 190° C. and a load of 2160 g is preferably 5 g/10 min or more, more preferably 10 g/10 min or more. On the other hand, the MFR of EVOH (A) is preferably 100 g/10 min or less, more preferably 40 g/10 min or less. When the MFR is within the above range, the melt moldability tends to be excellent.

EVOH (A) can be used alone or in combination of two or more.

(Additive (B))
By including the additive (B), the EVOH resin composition of the present invention can improve the fluidity of the resin composition while suppressing a decrease in tensile modulus and yield strength. In addition, by using the additive (B), bleeding out of the additive (B) from the resin composition can be suppressed.

Additive (B) is additive (B1) or additive (B2). Additive (B1) is a compound represented by the following general formula (1).

Each R ¹ in general formula (1) is independently a group selected from the group consisting of a hydroxyl group (-OH), a hydroxyalkyl group having 1 to 3 carbon atoms (-C _n H _2n OH: n = 1 to 3), and a hydroxyalkoxy group having 1 to 3 carbon atoms ( ^-OC _n H _2n OH: n = 1 to 3). +1: n=1 to 3) and an alkoxy group having 1 to 3 carbon atoms (--OC _{n H} 2n _{+1 :} n=1 to 3).

Among them, R ¹ is a group selected from a hydroxyl group (-OH) and a hydroxyalkoxy group having 1 to 3 carbon atoms (-OC _n H _2n OH: n = 1 to 3), and R ² is preferably a hydrogen atom (-H).

Additive (B2) is a compound represented by the following general formula (2).

R ³ and R ⁴ in general formula (2) are each independently an alkyl group having 1 to 20 carbon atoms and having at least one hydroxyl group. The number of hydroxyl groups is preferably 1 to 8, more preferably 1 to 5, still more preferably 1 to 3, and particularly preferably 1.

R ³ and R ⁴ are preferably C 10-20 alkyl groups having one or more hydroxyl groups, more preferably C 12-20 alkyl groups having one or more hydroxyl groups.

Among them, the additive (B2) is preferably meta-xylene bis-12-hydroxystearic acid amide because it can improve fluidity without lowering the yield strength and tensile modulus of the EVOH resin composition of the present invention.

From the viewpoint of suppressing bleeding out of the additive (B), the melting point of the additive (B) is preferably 100°C or higher, more preferably 120°C or higher. Moreover, the melting point of the additive (B) is preferably 200° C. or lower, more preferably 170° C. or lower, from the viewpoint of improving the fluidity of the EVOH resin composition of the present invention. The melting point of additive (B) can be measured according to JIS K0064:1992.

The content of additive (B) in the resin composition of the present invention is 0.01 to 20% by mass. If the content of the additive (B) is less than 0.01% by mass, the fluidity is not sufficiently improved. On the other hand, when the content of the additive (B) exceeds 20% by mass, the gas barrier properties of the resin composition tend to deteriorate, and the tensile elongation at break tends to decrease significantly. From the viewpoint of sufficiently improving fluidity, the content of additive (B) is preferably 3% by mass or more, more preferably 7% by mass or more. Moreover, from the viewpoint of maintaining good gas barrier properties and suppressing a decrease in tensile elongation at break, the content of the additive (B) is preferably 17% by mass or less, more preferably 12% by mass or less.

The MFR of the resin composition of the present invention measured in accordance with JIS K 7210:2014 at 190° C. and a load of 2160 g is preferably 5 g/10 min or more, more preferably 10 g/10 min or more. When the MFR at 190° C. and 2160 g load is 10 g/10 min or more, the fluidity becomes good and the external appearance of the obtained molded article tends to be good. In addition, the MFR of the resin composition of the present invention measured in accordance with JIS K 7210:2014 at 190° C. and a load of 2160 g may be 50 g/10 min or less, 40 g/10 min or less, or 30 g/10 min or less. Since the resin composition of the present invention contains the additive (B), the MFR of the resin composition is improved compared to the MFR of EVOH (A), and the fluidity is good.

(other ingredients)
The resin composition of the present invention may contain other components such as carboxylic acid compounds, phosphoric acid compounds, boron compounds, metal salts, stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, lubricants, coloring agents, fillers, desiccants, reinforcing agents such as various fibers, etc., as long as the effects of the present invention are not impaired.

When the resin composition of the present invention contains a carboxylic acid compound, it tends to prevent coloration during melt molding. The carboxylic acid contained in the resin composition of the present invention may be monocarboxylic acid, polyvalent carboxylic acid, or a combination thereof. The carboxylic acid contained in the resin composition of the present invention may be an ion, and such a carboxylic acid ion may form a salt with a metal ion. The content of carboxylic acid and carboxylic acid ion is preferably 1 to 400 ppm.

When the resin composition of the present invention contains a phosphoric acid compound, it tends to prevent coloration during melt molding. The phosphoric acid compound contained in the resin composition of the present invention is not particularly limited, and various acids such as phosphoric acid and phosphorous acid, salts thereof, and the like can be used. The phosphate may be contained in any form of primary phosphate, secondary phosphate, and tertiary phosphate, but primary phosphate is preferred. The cationic species is also not particularly limited, but alkali metal salts are preferred. Among these, sodium dihydrogen phosphate and potassium dihydrogen phosphate are preferred. When the resin composition of the present invention contains a phosphoric acid compound, the content of the phosphoric acid compound is preferably 1 to 500 ppm in terms of phosphate radical. When the content of the phosphoric acid compound is 1 ppm or more, the color resistance during melt molding tends to be good. On the other hand, when the content of the phosphoric acid compound is 500 ppm or less, the melt moldability tends to be good.

When the resin composition of the present invention contains a boron compound, it tends to be possible to suppress torque fluctuations during heating and melting. The boron compound contained in the resin composition of the present invention is not particularly limited, and examples thereof include boric acids, borate esters, borates, and boron hydrides. Specifically, examples of boric acids include orthoboric acid, metaboric acid, and tetraboric acid, examples of boric acid esters include triethyl borate and trimethyl borate, and examples of borate salts include alkali metal salts, alkaline earth metal salts, and borax of the various boric acids described above. Among these compounds, orthoboric acid (hereinafter sometimes simply referred to as boric acid) is preferred. When the resin composition of the present invention contains a boron compound, the content of the boron compound is preferably 20 to 2000 ppm in terms of boron element. When the content of the boron compound is 20 ppm or more, torque fluctuation during heating and melting tends to be suppressed. On the other hand, when the content of the boron compound is 2000 ppm or less, the moldability tends to be maintained well.

When the resin composition of the present invention contains an alkali metal salt, in a multilayer structure having a layer made of the resin composition of the present invention, the interlayer adhesion between the layer made of the resin composition of the present invention and another resin layer tends to be good. The cationic species of the alkali metal salt is not particularly limited, but sodium or potassium salts are preferred. The anion species of the alkali metal salt is also not particularly limited. They can be added as carboxylates, carbonates, hydrogen carbonates, phosphates, hydrogen phosphates, borates, hydroxides, and the like. When the resin composition of the present invention contains an alkali metal salt, the content of the alkali metal salt is preferably 10 to 500 ppm in terms of metal element. When the content of the alkali metal salt is 10 ppm or more, the interlayer adhesion tends to be good. On the other hand, when the content of the alkali metal salt is 500 ppm or less, the melt stability tends to be excellent.

When the resin composition of the present invention contains an alkaline earth metal salt, it tends to be possible to suppress deterioration and generation of deteriorated products such as gel when the molded article is repeatedly melt-molded. Although the cationic species of the alkaline earth metal salt is not particularly limited, magnesium salts or calcium salts are preferred. The anion species of the alkaline earth metal salt is also not particularly limited. They can be added as carboxylates, carbonates, hydrogen carbonates, phosphates, hydrogen phosphates, borates, hydroxides, and the like. When the resin composition of the present invention contains an alkaline earth metal salt, the content of the alkaline earth metal salt is preferably 10 to 500 ppm.

Stabilizers for improving melt stability and the like include hydrotalcite compounds, hindered phenol compounds, hindered amine heat stabilizers, metal salts of higher aliphatic carboxylic acids (e.g., calcium stearate, magnesium stearate, etc.), etc. When the resin composition of the present invention contains a stabilizer, the content thereof may be 0.001 to 1% by mass.

Antioxidants include 2,5-di-t-butyl-hydroquinone, 2,6-di-t-butyl-p-cresol, 4,4'-thiobis-(6-t-butylphenol), 2,2'-methylene-bis-(4-methyl-6-t-butylphenol), octadecyl-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate, 4,4'-thiobis-(6-t-butylphenol). etc.

Examples of UV absorbers include ethylene-2-cyano-3,3'-diphenyl acrylate, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)5-chlorobenzotriazole, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone and the like.

When the resin composition of the present invention contains the other components, the ratio of EVOH (A) and additive (B) in the resin composition of the present invention is preferably 95% by mass or more, more preferably 97% by mass or more, and even more preferably 99% by mass or more.

Although the method for producing the resin composition of the present invention is not particularly limited, it can be produced, for example, by mixing or kneading EVOH (A) and additive (B) under melting conditions. Mixing or kneading under melt conditions can be carried out using known mixing or kneading equipment such as kneader ruders, extruders, mixing rolls, Banbury mixers and the like. The temperature during mixing or kneading may be appropriately adjusted according to the melting point of the EVOH (A) used, and a temperature within the temperature range of 160°C to 300°C is usually employed.

Further, the melting point of the resin composition of the present invention is preferably 120° C. or higher, more preferably 150° C. or higher, for the reason that melt molding is facilitated. Moreover, the melting point of the resin composition of the present invention is preferably 220° C. or lower, more preferably 190° C. or lower.

<Molded body>
Molded articles made of the resin composition of the present invention can be molded using ordinary molding methods and molding apparatuses that are used for general thermoplastic polymers because the resin composition of the present invention has thermoplasticity. As the molding method, any method such as injection molding, extrusion molding, press molding, blow molding, calender molding, vacuum molding, compression molding, and the like can be employed. The shape of the molded body containing the resin composition produced by such a method includes a wide variety of shapes such as molds, pipes, sheets, films, discs, rings, bags, bottles, cords, fibrous materials, etc. Films are preferred. The molded article may substantially contain only the resin composition.

The molded article of the present invention can be used, for example, as a single-layer film-like structure. Suitable uses of the molded product are packaging materials for food and drink, packing materials for containers, bag materials for medical infusions, gasoline tank materials, tire tube materials, packaging materials for cosmetics, packaging materials for medicines, packaging materials for toothpaste, and cushioning materials for shoes.

<Multilayer structure>
The multilayer structure of the present invention has a layer containing the resin composition. The layer containing the resin composition may be a layer containing substantially only the resin composition. The multilayer structure of the present invention can improve moisture resistance, mechanical properties, etc. by having a layer containing the resin composition. The number of layers constituting the multilayer structure is not particularly limited as long as it is 2 or more layers, but for example, 2 to 10 layers is preferable, and 3 to 5 layers is more preferable.

The multilayer structure of the present invention has, for example, at least one layer containing the resin composition (the resin composition layer) and at least one layer composed of another material. Other materials can be appropriately selected depending on the required properties, intended use, etc. Examples include polyolefins such as high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, ethylene-propylene copolymer, and polypropylene; thermoplastic polymers such as ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, polystyrene, vinyl chloride resin, and vinylidene chloride resin;

In the multilayer structure of the present invention, an adhesive layer or an adhesive may be interposed between the resin composition layer and a layer composed of another material. By interposing an adhesive layer or an adhesive, the two layers on both sides can be firmly joined and integrated. Examples of the adhesive layer and adhesive include acid anhydride-modified diene polymers, acid anhydride-modified polyolefins, and mixtures of polymer polyols and polyisocyanate compounds. However, when the layer composed of another material is a polyolefin layer, the interlayer adhesion is excellent even without an adhesive layer or an adhesive, so an adhesive layer or an adhesive may not be interposed. In addition, known methods such as co-extrusion, co-injection, and extrusion coating can also be used for forming the multilayer structure of the multilayer structure.

Since the multilayer structure of the present invention has excellent gas barrier properties and mechanical properties in a well-balanced manner, it can be used as daily necessities, packaging materials, machine parts, etc. that require these properties. Examples of applications in which the features of the multilayer structure are particularly effectively exhibited include food and drink packaging materials, container packing materials, medical infusion bag materials, gasoline tank materials, tire tube materials, cosmetic packaging materials, pharmaceutical packaging materials, toothpaste packaging materials, shoe cushion materials, containers, bag-in-box inner bag materials, organic liquid storage tank materials, organic liquid transport pipe materials, hot water pipe materials for heating (hot water pipe materials for floor heating, etc.), resin wallpaper, and the like.

EXAMPLES The present invention will be further described below with reference to examples, but the present invention is not limited by these examples.

[Example 1]
Ethylene-vinyl alcohol copolymer (A) is ethylene unit content of 44 mol%, degree of saponification is 99.9 mol%, 95 parts by mass of EVOH having MFR of 12 g/10 min at 190°C, and 5 parts of Ogsol MF-11 (B1-1) manufactured by Osaka Gas Chemicals Co., Ltd. are dry-blended as additive (B1). After kneading at rpm for 3 minutes, the mixture was kneaded at 50 rpm for 7 minutes and cut with scissors to obtain a 5 mm square melt-blended product.

[Melt flow rate (MFR)]
Using a melt indexer (L244 manufactured by Takara Kogyo Co., Ltd.), the outflow rate (g/10 min) of the sample was measured in accordance with JIS K 7210:2014 under conditions of a temperature of 190°C and a load of 2160 g for the melt blended product obtained above to obtain the MFR.

[Melting point (Tm) of resin composition]
According to JIS K7121: 2012, the melt blended product obtained above was heated from 30 ° C. to 210 ° C. at a rate of 10 ° C./min, cooled to 50 ° C. at 10 ° C./min, and measured again from 50 ° C. to 210 ° C. at a temperature increase rate of 10 ° C./min (Differential Scanning Calorimeter (DSC) "DSC-60A" manufactured by Shimadzu Corporation). The melting peak temperature (Tpm) was determined from the 2nd run chart according to the JIS, and was taken as the melting point of the resin composition.

[Film production]
3 g of the melt blended product obtained above was placed in an aluminum frame of 10 cm × 10 cm, and was pressed at 200 ° C. with a pressure of 10 MPa using a hot press (manufactured by Imoto Seisakusho Co., Ltd., model: MH-10) to obtain a 300 μm thick film (hereinafter referred to as a sample film).

[Yield strength, breaking elongation, tensile modulus]
A dumbbell shape was cut from the sample film to obtain a test piece. The sample piece had a total length of 60 mm, a central portion length of 10 mm, a central portion width of 4 mm, and a thickness of 300 μm. Using a precision universal testing machine (trade name: Autograph EZ-Test, compatible with JIS B 7721:2009 class 0.5 and ISO 7500-1 (2004) class 0.5, manufactured by Shimadzu Corporation), the test piece was subjected to a constant-speed tensile test under the conditions of a chuck distance of 10 mm and a tensile speed of 20 mm/min, and the yield strength, elongation at break, and tensile elastic modulus were measured.

[Long period, lamellar thickness, amorphous thickness]
The long period, lamellar thickness, and amorphous thickness of the sample film were measured using a small-angle X-ray scattering apparatus (BL40B2 of large synchrotron radiation facility (Spring-8)) under the following conditions.
Standard sample: Silver behenate Wavelength: 1 Å
Exposure time: 5s

[Bleed out]
The sample film was stored under conditions of 40° C./100% RH for 7 days, and bleed-out was visually confirmed and judged as follows.
A: Bleed-out does not occur.
B: Bleed-out occurred.
Table 1 shows the measurement results obtained.

(Examples 2 to 4, Comparative Example 1)
As shown in Table 1, a melt-blended product (resin composition) and a sample film were produced and evaluated in the same manner as in Example 1, except that the amount and type of additives added were changed. Table 1 shows the results. In the table, additive (B2-1) represents meta-xylene bis-12-hydroxystearic acid amide.

The melt-blended products of Examples 2 and 4 and Comparative Example 1 were measured for viscoelasticity, dynamic viscoelasticity, and free volume according to the following methods, and the evaluation results are shown in FIGS.
[Viscoelasticity]
The melt viscosity in the low shear region of the obtained melt-blended product was measured using a rotary rheometer (MCR302 manufactured by AntonPaar) under the following conditions.
Atmosphere: Nitrogen Measurement temperature: 200°C
Strain: 1.0%
[Dynamic viscoelasticity]
The dynamic viscosity of the obtained sample film was measured using a dynamic viscoelasticity measuring device (RHEOGEL-E4000 manufactured by UBM Co., Ltd.) under the following conditions.
Between chucks: 2 cm
Frequency: 8Hz
Heating rate: 3°C/min
[Free volume]
The free volume of the obtained sample film was measured using a positron annihilation lifetime measurement device under the following conditions.
Temperature: 23°C, vacuum positron source: ²² Na
Analysis software: PALS Fits

From the comparison of the examples and comparative examples, it can be seen that by using specific additives, bleed-out does not occur, the deterioration of physical properties such as tensile modulus and yield strength is suppressed, and fluidity is effectively improved. From viscoelastic measurements in the crystallization speed, long-period, and low-frequency regions, the composition containing the additive (B1) retards the crystallization process, but has the characteristic of maintaining the network structure due to hydrogen bonding. The composition containing additive (B2) promotes crystallization, but is believed to have the characteristic of breaking hydrogen bonds in the molten state.

It is not limited to the use of the present invention, and can be applied to a wide range of fields such as food, medicine, industrial chemicals, and agricultural chemicals.

Claims (6)

An ethylene-vinyl alcohol copolymer resin composition comprising an ethylene-vinyl alcohol copolymer (A) and an additive (B), wherein the additive (B) is an additive (B1) represented by the following general formula (1) or an additive (B2) represented by the following general formula (2), and the content of the additive (B) is 0.01 to 20% by mass.

[In the formula, each R ¹ is independently a hydroxyl group or a hydroxyalkoxy group having 1 to 3 carbon atoms, and R ² is a hydrogen atom . ]

[In the formula, R ³ and R ⁴ are each independently an alkyl group having 12 to 20 carbon atoms and having one hydroxyl group. ] The ethylene-vinyl alcohol copolymer resin composition according to claim 1, wherein the additive (B) has a melting point of 100°C or higher and 200°C or lower. 3. The ethylene-vinyl alcohol copolymer resin composition according to claim 1, wherein the additive (B2) is meta-xylene bis-12-hydroxystearic acid amide. The ethylene-vinyl alcohol copolymer resin composition according to any one of claims 1 to 3, wherein the ethylene-vinyl alcohol copolymer (A) has an ethylene unit content of 20 to 60 mol%. A molded article comprising the ethylene-vinyl alcohol copolymer resin composition according to any one of claims 1 to 4. A multilayer structure comprising at least one layer comprising the ethylene-vinyl alcohol copolymer resin composition according to any one of claims 1 to 4.

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