JP6780922B2 - Resin compositions, films, multilayer structures and packaging materials - Google Patents

Description

The present invention relates to resin compositions, films, multilayer structures and packaging materials.

A resin composition containing an ethylene-vinyl alcohol copolymer (hereinafter, also referred to as “EVOH resin composition”) has excellent gas barrier properties, is molded into a film, a sheet, a container, or the like, and is widely used as various packaging materials. Further, a multilayer structure obtained by laminating an EVOH film and a thermoplastic resin having excellent moisture resistance, mechanical properties and the like, particularly a polyolefin-based resin film, is used as a packaging material in various fields. Such packaging materials are widely used in various fields such as foods, cosmetics, medical chemicals, toiletries, vacuum insulation plates, etc. as containers having excellent oxygen barrier properties, for example, in the form of bags, tubes, cups, pouches, etc. Has been done. The EVOH resin composition used for these containers and the like is required to satisfy various properties such as the following.

The EVOH resin composition is required to have high appearance characteristics even after melt molding, such as no yellow coloring on the end face of the roll after being wound as a roll in the film molding step. Further, the EVOH resin composition has a performance capable of suppressing film breakage due to tension between rolls during a film unwinding process or processing when laminating with another thermoplastic resin or when vapor deposition processing of aluminum, silicon oxide or the like. (Film breakability) is required. Further, when the EVOH resin composition is molded into a film, it is also required to have excellent slipperiness (blocking resistance) between films when stored as a film roll and slipperiness with a production roll during laminating. There is also.

Further, in order to improve the gas barrier property and the moisture-proof property, a thin-film deposition layer made of a metal such as aluminum or an inorganic oxide such as silica or alumina may be laminated on the surface of the EVOH film to form a multilayer structure having the vapor-deposited layer. Will be done. Since the vapor deposition defects such as pinholes that may occur during the vapor deposition process lower the gas barrier performance (see Japanese Patent Application Laid-Open No. 2005-290108), the EVOH film has the vapor deposition defects that occur during the vapor deposition process and the occurrence thereof. Performance that can suppress an increase over time (evaporation defect suppression property) is required. Further, in the multilayer structure having the thin-film vapor deposition layer, it is also required to improve the adhesion strength between the thin-film deposition layer and the EVOH film and suppress delamination or the like which causes poor appearance.

In response to the above various requirements, in order to prevent the occurrence of coloring such as yellowing in melt molding, an acid such as carboxylic acid or phosphoric acid or a metal salt such as an alkali metal salt or an alkaline earth metal salt is appropriately contained. Various methods have been proposed for containing in an amount (see JP-A-2001-146539). Further, in order to improve the slipperiness and blocking resistance of the film, it has been proposed to contain an oxide and a boron compound (see JP-A-2000-265024). Further, in order to suppress the deterioration of gas barrier performance due to pinholes in the vapor deposition process, a surface treatment resin film having a molar ratio of oxygen atoms and carbon atoms on the film surface of 0.24 or more is used to treat metallic aluminum or silicon oxide. It has been proposed to use a multilayer structure containing at least one layer (see JP-A-2005-290108).

However, the method of containing an acid or a metal salt in the above-mentioned Japanese Patent Application Laid-Open No. 2001-146539 in an appropriate content has not sufficiently suppressed the occurrence of coloring such as yellowing in melt molding. Further, although the slipperiness and blocking resistance of the film are improved by adding the oxide and boron compounds of JP-A-2000-265024, the suppression of the occurrence of pinholes in the vapor deposition process and the laminating processability are insufficient. .. Further, in the multilayer structure of JP-A-2005-290108, since the occurrence of pinholes in the layer treated with metallic aluminum or silicon oxide cannot be reduced, there is a concern that the barrier property may be lowered. As described above, the above-mentioned conventional resin composition and the multilayer structure cannot satisfy the above-mentioned requirements.

Japanese Unexamined Patent Publication No. 2005-290108 JP 2001-146539 Japanese Unexamined Patent Publication No. 2000-265024

The present invention has been made based on the above circumstances, and an object of the present invention is the appearance characteristics after melt molding such as the color of the film end (roll end), film breakage resistance, and thin film deposition defect suppressing property. An object of the present invention is to provide a resin composition having excellent adhesion strength of a thin-film deposition layer, and a film, a multilayer structure and a packaging material using this resin composition.

The invention made to solve the above problems is
Ethylene-vinyl alcohol copolymer (hereinafter, also referred to as "EVOH (A)") and inorganic particles (hereinafter, also referred to as "inorganic particles (B)") obtained by saponifying a copolymer of ethylene and vinyl ester. A resin composition containing, and measured after heat treatment at 220 ° C. for 50 hours under the nitrogen atmosphere of EVOH (A) using a gel permeation chromatograph equipped with a differential refractometer detector and an ultraviolet visible absorbance detector. It is characterized in that the molecular weight satisfies the condition represented by the following formula (1).
(Ma-Mb) / Ma <0.45 ... (1)
Ma: Polymolecular weight in terms of polymethylmethacrylate at the maximum value of the peak measured by the differential refractive index detector Mb: Poly at the maximum value of the absorption peak at a wavelength of 220 nm measured by the ultraviolet-visible absorbance detector at the same time as the measurement of Ma. Molecular weight in terms of methyl methacrylate

By containing EVOH (A) that satisfies the above-mentioned specific conditions, the resin composition is excellent in appearance characteristics after melt molding, film breakage resistance, vapor deposition defect suppressing property, and adhesion strength of the vapor deposition layer.

The molecular weight measured after heat treatment at 220 ° C. for 50 hours under the nitrogen atmosphere of EVOH (A) using a gel permeation chromatograph equipped with a differential refractive index detector and an ultraviolet-visible absorbance detector is represented by the following formula (2). It is preferable to further satisfy the conditions to be satisfied.
(Ma-Mc) / Ma <0.45 ... (2)
Mc: Molecular weight in terms of polymethyl methacrylate at the maximum value of the absorption peak at a wavelength of 280 nm measured by an ultraviolet-visible absorbance detector

As described above, when the EVOH (A) contained in the resin composition further satisfies the above-mentioned specific conditions, the appearance characteristics after melt molding, film breakage resistance, vapor deposition defect suppressing property, and adhesion strength of the vapor deposition layer are further improved. it can.

The content of the inorganic particles (B) is preferably 50 ppm or more and 5,000 ppm or less. As described above, it is considered that the inorganic particles (B) can be appropriately dispersed by setting the content of the inorganic particles (B) within the above-mentioned specific range, and the arithmetic average roughness (Ra) and contour of the film surface can be dispersed. The average length (RSm) of the curved elements can be in an appropriate range. As a result, the film breaking resistance of the resin composition and the adhesion strength of the vapor-deposited layer can be further improved.

The average particle size of the inorganic particles (B) is preferably 0.5 μm or more and 10 μm or less. By setting the average particle size of the inorganic particles (B) to the above-mentioned specific range in this way, Ra on the film surface can be adjusted to a more appropriate range, and as a result, film breakage resistance and vapor deposition defect suppression property are suppressed. And the adhesion strength of the thin-film deposition layer can be further improved.

The metal element constituting the inorganic particles is preferably at least one selected from the group consisting of silicon, aluminum, magnesium, zirconium, cerium, tungsten and molybdenum. Further, the inorganic substance constituting the inorganic particles may be an oxide of the metal element. As described above, when the resin composition contains the specific inorganic particles (B), the appearance characteristics after melt molding can be further improved.

The present invention includes a film formed from the resin composition. Since the film is formed from the resin composition, it is excellent in appearance characteristics and film breakage resistance.

The arithmetic mean roughness (Ra) of at least one surface measured in accordance with JIS-B0601: 2001 of the above film is preferably 0.05 μm or more and 1 μm or less. By setting Ra on at least one surface of the film to the above-mentioned specific range, the film breakability can be further improved.

The average length (RSm) of the contour curve element of at least one surface measured in accordance with JIS-B0601: 2001 of the film is preferably 50 μm or more and 1,000 μm or less. By setting the RSm on at least one surface of the film to the above-mentioned specific range, the film breakability can be further improved.

The present invention includes a multilayer structure having a plurality of layers, wherein at least one of the plurality of layers is the film. Since the multilayer structure has a plurality of layers and at least one of the plurality of layers is the film, there are few vapor deposition defects and the adhesion strength between the metal vapor deposition layer and the other resin layer is excellent. ..

In the multilayer structure, at least one of the plurality of layers is preferably a metal vapor deposition layer. In this case, the total average thickness of the metal vapor deposition layers is preferably 30 nm or more and 150 nm or less. As described above, when the multilayer structure has the metal vapor deposition film having the thickness in the specific range, the vapor deposition defects can be suppressed, and the adhesion strength between the metal vapor deposition layer and the other resin layer can be further improved.

In the multilayer structure, the metal vapor deposition layer may be the outermost layer of the plurality of layers. As described above, since the outermost layer of the plurality of layers of the multilayer structure is the metal vapor deposition layer, the appearance characteristics after melt molding, film fracture resistance, vapor deposition defect suppression property, and adhesion of the metal vapor deposition layer are achieved. The strength can be further improved.

The present invention includes a packaging material comprising the multilayer structure. The packaging material is excellent in appearance characteristics and film breakage resistance by providing the above-mentioned multilayer structure.

Here, when the content of each component is represented by "ppm", this "ppm" means the mass ratio of the content of each component, and 1 ppm is 0.0001 mass%.

As described above, the resin composition of the present invention is excellent in appearance characteristics after melt molding such as the color of the film end (roll end), film breakage resistance, vapor deposition defect suppressing property, and adhesion strength of the vapor deposition layer. .. The film of the present invention is excellent in appearance characteristics such as color of the film end (roll end) and film breakage resistance. The multilayer structure of the present invention has few vapor deposition defects and is excellent in adhesion strength between the metal vapor deposition layer and other resin layers. The packaging material of the present invention is excellent in appearance characteristics and film breakability. Therefore, these can be suitably used as various packaging materials.

The relationship between the molecular weight of EVOH (logarithmic value) and the signal value (RI) measured by the differential refractive index detector and the absorbance (UV) measured by the absorbance detectors (measurement wavelengths 220 nm and 280 nm) is schematically shown. It is a graph.

Hereinafter, embodiments of the present invention will be described in the order of the resin composition, the film formed from the resin composition, the multilayer structure provided with the film, and the packaging material provided with the multilayer structure. The present invention is not limited to these. Further, as for the illustrated materials, unless otherwise specified, one kind may be used alone, or two or more kinds may be used in combination.

<Resin composition>
The resin composition of the present invention contains EVOH (A) and inorganic particles (B). The resin composition may further contain an alkali metal salt (C), other optional components, and the like, in addition to EVOH (A) and inorganic particles (B).

[EVOH (A)]
EVOH (A) is the main component of the resin composition. EVOH (A) is a saponified copolymer of ethylene and vinyl ester. Here, the "main component" is a component having the highest content, for example, a component having a content of 50% by mass or more. The lower limit of the content of EVOH (A) in the resin content of the resin composition is preferably 70% by mass, more preferably 90% by mass, and even more preferably 95% by mass.

The copolymerization method of ethylene and vinyl ester is not particularly limited, and known methods such as solution polymerization, suspension polymerization, emulsion polymerization, and bulk polymerization can be used. Further, the above-mentioned copolymerization method may be either a continuous method or a batch method.

The lower limit of the ethylene content of EVOH (A) is preferably 10 mol%, more preferably 20 mol%, still more preferably 25 mol%. On the other hand, the upper limit of the ethylene content of EVOH (A) is preferably 60 mol%, more preferably 55 mol%, further preferably 50 mol%, and particularly preferably 40 mol%. If the ethylene content is less than the above lower limit, the thermal stability during melt extrusion is lowered and gelation is likely to occur, and film forming defects such as streaks and fish eyes may be likely to occur. In particular, if the operation is performed for a long time under the conditions of high temperature or high speed than the conditions at the time of general melt extrusion, the possibility of gelation increases. On the other hand, if the ethylene content exceeds the above upper limit, the gas barrier property and the like may be lowered, and the advantageous characteristics of EVOH may not be sufficiently exhibited.

As the vinyl ester, vinyl acetate is preferably used from the viewpoint of industrial availability and the like. This vinyl acetate usually contains a small amount of acetaldehyde as an unavoidable impurity. The acetaldehyde content of this vinyl acetate is preferably less than 100 ppm. The upper limit of the acetaldehyde content of vinyl acetate is more preferably 60 ppm, further preferably 25 ppm, and particularly preferably 15 ppm. By setting the acetaldehyde content of vinyl acetate in the above range, it becomes easy to prepare EVOH (A) satisfying the formula (1) described later.

EVOH (A) may contain other structural units derived from monomers other than ethylene and vinyl esters. Examples of the monomer giving such another structural unit include vinylsilane compounds and other polymerizable compounds. The content of the other structural units is preferably 0.0002 mol% or more and 0.2 mol% or less with respect to all the structural units of EVOH (A).

(Degree of ken)
The lower limit of the degree of saponification of the structural unit derived from the vinyl ester of EVOH (A) is usually 85 mol%, preferably 90 mol%, more preferably 98 mol%, still more preferably 98.9 mol%. If the degree of saponification is less than the above lower limit, the thermal stability may be insufficient.

(Peak top molecular weight (Ma))
The peak top molecular weight (Ma) is determined by separating EVOH (A) after heat treatment at 220 ° C. for 50 hours under a nitrogen atmosphere by gel permeation chromatography (hereinafter, also referred to as “GPC”), and at this time, from the column. It is a value corresponding to the maximum value of the main peak of the signal (“RI” in FIG. 1) measured by the differential refractive index detector as schematically shown in FIG. 1 of the eluted EVOH (A). The peak top molecular weight (Ma) in the present invention is a value of polymethyl methacrylate conversion (hereinafter, also referred to as “PMMA conversion”) calculated using a calibration curve prepared by the method described later.

As the lower limit of the peak top molecular weight (Ma), 30,000 is preferable, 35,000 is more preferable, 40,000 is further preferable, and 50,000 is particularly preferable. On the other hand, as the upper limit of the peak top molecular weight (Ma), 100,000 is preferable, 80,000 is more preferable, 65,000 is further preferable, and 60,000 is particularly preferable.

(Absorption peak molecular weight (Mb) and (Mc))
As shown schematically in FIG. 1, the absorption peak molecular weights (Mb) and (Mc) are measured by separating EVOH (A) by GPC under the same conditions as the measurement of the peak top molecular weight (Ma) and measuring with an ultraviolet-visible absorbance detector. It is a value corresponding to the maximum value of the absorption peak of the signal (“UV” in FIG. 1) at a specific wavelength. The absorption peak molecular weights (Mb) and (Mc) are molecular weights in terms of polymethyl methacrylate. The molecular weight of the absorption peak at a wavelength of 220 nm is expressed as “Mb”, and the molecular weight of the absorption peak at a wavelength of 280 nm is expressed as “Mc”.

As the lower limit of the absorption peak molecular weight (Mb), 30,000 is preferable, 35,000 is more preferable, 40,000 is further preferable, and 50,000 is particularly preferable. On the other hand, the upper limit of the absorption peak molecular weight (Mb) is preferably 75,000, more preferably 60,000, and even more preferably 55,000.

As the lower limit of the absorption peak molecular weight (Mc), 35,000 is preferable, 40,000 is more preferable, 45,000 is further preferable, and 48,000 is particularly preferable. On the other hand, the upper limit of the absorption peak molecular weight (Mc) is preferably 75,000, more preferably 55,000, and even more preferably 50,000.

(Creation of calibration curve)
The calibration curve is, for example, a monodisperse PMMA (peak top molecular weight: 1,944,000, 790,000,467,400, 271,400, 144,000, 79,250, 35,300) manufactured by Agilent Technologies as a standard. , 13,300,7,100,1,960,1,020,690), and prepare for each of the differential refractive index detector and the absorbance detector. It is preferable to use analysis software to create the calibration curve. In the PMMA measurement of this measurement, for example, a column capable of separating peaks between standard samples having both molecular weights of 1,944,000 and 271,400 is used.

(Molecular weight correlation of EVOH (A))
EVOH (A) satisfies the condition represented by the following formula (1).

(Ma-Mb) / Ma <0.45 ... (1)

The left side (Ma-Mb) / Ma of the formula (1) is preferably less than 0.40, more preferably less than 0.30, and even more preferably less than 0.10. Here, the smaller the difference between the Ma and Mb (Ma-Mb), the main peak (P _RI) and the absorption peak obtained from ultraviolet-visible absorbance detector (P _UV obtained from the differential refractive index detector in FIG. 1 (220 nm)) means that they are in close proximity. On the contrary, when the value of the molecular weight difference (Ma-Mb) becomes large, it means that these two peaks ( _PRI and _PUV (220 nm)) are separated from each other. That is, when the value of the molecular weight difference (Ma-Mb) of both peaks ( _PRI , _PUV (220 nm)) is large, it means that there are many components having a relatively low molecular weight that absorb ultraviolet rays having a wavelength of 220 nm. To do. Therefore, when EVOH (A) does not satisfy the above formula (1), it means that there are many components having a relatively low molecular weight that absorb ultraviolet rays having a wavelength of 220 nm. In this case, EVOH (A) is thermally deteriorated during melt molding using the resin composition containing EVOH (A), and there is a tendency that coloring of the film edge and deterioration of the film deposition defect suppressing property become apparent. As a result, the appearance characteristics of the formed film, the fracture resistance of the film, and the adhesion strength of the vapor-deposited layer are lowered.

The effect of satisfying the above equation (1) is considered to occur for the following reasons. That is, EVOH causes thermal deterioration such as dehydration to generate carbon-carbon double bonds and carbonyl groups in the molecule that absorb ultraviolet rays having a wavelength of 220 nm, and these groups promote gelation of the resin composition. .. The gelation-promoting action depends on the molecular weight of the heat-deteriorated EVOH. When the molecular weight of the heat-deteriorated EVOH is large, the promoting action is weak, and the smaller the molecular weight, the stronger the promoting action. Therefore, when EVOH satisfies the above formula (1), that is, when a relatively high molecular weight can be maintained even after thermal deterioration, the appearance characteristics of the formed film, the film breakage resistance, and the adhesion strength of the vapor-deposited layer can be improved. it is conceivable that.

EVOH (A) preferably satisfies the condition of the following formula (2).

(Ma-Mc) / Ma <0.45 ... (2)

The left side (Ma-Mc) / Ma of the formula (2) is more preferably less than 0.40, further preferably less than 0.30, and particularly preferably less than 0.15. Here, if the value of the left side (Ma-Mc) / Ma of the equation (2) becomes large, the main peak ( _PRI ) obtained from the differential refractive index detector and the absorption peak (P) obtained from the ultraviolet-visible absorbance detector It is separated from _UV (280 nm)), and a large number of components absorb ultraviolet rays having a wavelength of 280 nm in a component having a relatively low molecular weight. In this case, EVOH tends to be thermally deteriorated during melt molding, and the coloring of the film edge and the deterioration of the film deposition defect suppressing property tend to become apparent. As a result, the appearance characteristics of the obtained film, the fracture resistance of the film, and the adhesion strength of the vapor-deposited layer are lowered.

The effect of satisfying the above equation (2) is considered to occur for the following reasons. That is, EVOH has a conjugated double bond in the molecule that absorbs ultraviolet rays having a wavelength of 280 nm as the carbon-carbon double bond or carbonyl group is generated in the molecule due to the above-mentioned thermal deterioration and then the thermal deterioration further progresses. This conjugated double bond promotes yellowing of the resin composition. Similar to the above-mentioned gelation promoting action, the above-mentioned yellowing promoting action depends on the molecular weight of the heat-deteriorated EVOH, and when the heat-deteriorated EVOH has a large molecular weight, the above-mentioned promoting action is weak and the molecular weight is small. Indeed, the above-mentioned promoting action becomes stronger. Therefore, when EVOH satisfies the above formula (2), that is, when a relatively high molecular weight can be maintained even if thermal deterioration progresses, the appearance characteristics of the obtained film, film breakage resistance, and adhesion strength of the vapor-deposited layer are further improved. It is thought that it can be improved.

(Method of preparing EVOH (A) satisfying the condition represented by the formula (1))
As a method for preparing EVOH (A) satisfying the condition represented by the formula (1), in the conventional preparation of EVOH,
(A) A method for removing a radical polymerization inhibitor contained in vinyl ester in advance in preparation of a copolymer of ethylene and vinyl ester as raw materials.
(B) A method for setting a specific amount of impurities contained in vinyl ester used for radical polymerization in the preparation of a copolymer of ethylene and vinyl ester as raw materials.
(C) A method of setting the polymerization temperature within a specific range in the preparation of a copolymer of ethylene and vinyl ester as raw materials.
(D) In the preparation of a copolymer of ethylene and vinyl ester as a raw material, a method of adding an organic acid in a polymerization step or a step of recovering and reusing unreacted vinyl ester after the polymerization step.
(E) A method for setting a specific amount of impurities in the solvent used for polymerization in the preparation of a copolymer of ethylene and vinyl ester as raw materials.
(F) A method for increasing the mass ratio (solvent / vinyl ester) of the solvent used for polymerization and vinyl ester in the preparation of a copolymer of ethylene and vinyl ester as a raw material.
(G) A method using an azonitrile-based initiator or an organic peroxide-based initiator as the radical polymerization initiator used when radically polymerizing ethylene and a vinyl ester monomer.
(H) In the preparation of a copolymer of ethylene and vinyl ester as a raw material, the amount added when a radical polymerization inhibitor is added after radical polymerization is set to a specific amount with respect to the remaining undecomposed radical polymerization initiator. Method,
(I) A method of using an alcohol solution of a copolymer of ethylene and vinyl ester from which residual vinyl ester has been removed as much as possible for a saponification reaction.
(J) A method of adding an antioxidant to the copolymer of ethylene and vinyl ester used for saponification can be mentioned, and (A) to (J) may be appropriately combined. Further, EVOH (A) satisfying the condition represented by the formula (2) can be prepared by (A) to (J). The methods (A) to (J) will be described below.

((A) A method of removing a radical polymerization inhibitor contained in vinyl ester in advance in the preparation of a copolymer of ethylene and vinyl ester as raw materials)
Examples of the radical polymerization inhibitor include those similar to those exemplified as the radical polymerization inhibitor added after radical polymerization in (H) described later. Examples of the method for removing the radical polymerization inhibitor include a method using column chromatography, a reprecipitation method, a distillation method and the like, and a usual distillation method is adopted. When the radical polymerization inhibitor is removed by the distillation method, the boiling point of the vinyl ester is lower than the boiling point of the radical polymerization inhibitor, so that the vinyl ester from which the polymerization inhibitor has been removed can be obtained from the top of the distillation column.

((B) In the preparation of a copolymer of ethylene and vinyl ester as a raw material, a method of setting an impurity contained in vinyl ester used for radical polymerization to a specific amount)
As the lower limit of the total content of impurities contained in the vinyl ester used for radical polymerization, 1 ppm is preferable, 3 ppm is more preferable, and 5 ppm is further preferable. The upper limit of the total content of the impurities is preferably 1,200 ppm, more preferably 1,100 ppm, still more preferably 1,000 ppm.

Examples of the impurities include aldehydes such as acetaldehyde, crotonaldehyde and achlorein; acetals such as acetaldehyde dimethyl acetal, crotonaldehyde dimethyl acetal and achlorein dimethyl acetal in which this aldehyde is acetalized by alcohol as a solvent; ketones such as acetone; methyl acetate and acetic acid. Examples thereof include esters such as ethyl.

Of the above impurities, acetaldehyde is likely to be generated in the production of vinyl acetate and the like, and it is easy to prevent EVOH (A) from satisfying the formula (1). Therefore, in this method, it is particularly preferable to reduce the content of acetaldehyde.

((C) A method in which the polymerization temperature is within a specific range in the preparation of a copolymer of ethylene and vinyl ester as raw materials)
The lower limit of the polymerization temperature of the copolymer of ethylene and vinyl ester is preferably 20 ° C, more preferably 40 ° C. On the other hand, the upper limit of the polymerization temperature is preferably 90 ° C., more preferably 70 ° C.

(D) In the preparation of a copolymer of ethylene and vinyl ester as a raw material, an alcohol solvent is used, and an organic acid is added in a polymerization step or a step of recovering and reusing unreacted vinyl ester after the polymerization step. Method)
In this method, the production of aldehydes such as acetaldehyde can be suppressed by suppressing the alcohol-added decomposition of vinyl ester by alcohol and the hydrolysis by a small amount of water by adding an organic acid to the polymerization system. Examples of the organic acid include hydroxycarboxylic acids such as glycolic acid, glyceric acid, malic acid, citric acid, lactic acid, tartaric acid and salicylic acid; and polyvalents such as malonic acid, succinic acid, maleic acid, phthalic acid, oxalic acid and glutaric acid. Examples include carboxylic acid.

As the lower limit of the amount of the organic acid added, 1 ppm is preferable, 3 ppm is more preferable, and 5 ppm is further preferable. The upper limit of the amount of the organic acid added is preferably 500 ppm, more preferably 300 ppm, still more preferably 100 ppm.

((E) In the preparation of a copolymer of ethylene and vinyl ester as raw materials, a method of setting an impurity of a solvent used for polymerization as a specific amount)
The lower limit of the total content of impurities in the solvent used for the polymerization is preferably 1 ppm, more preferably 3 ppm, still more preferably 5 ppm. The upper limit of the total content of the impurities is preferably 1,200 ppm, more preferably 1,100 ppm, still more preferably 1,000 ppm. Examples of the impurities of the solvent used for the polymerization include those exemplified as the impurities contained in the vinyl ester described above.

((F) Method for increasing the mass ratio (solvent / vinyl ester) of the solvent used for polymerization and vinyl ester in the preparation of a copolymer of ethylene and vinyl ester as a raw material)
The lower limit of the mass ratio (solvent / vinyl ester) of the solvent used for the polymerization and the vinyl ester is preferably 0.03. On the other hand, the upper limit of the mass ratio (solvent / vinyl ester) is, for example, 0.4.

((G) A method using an azonitrile-based initiator or an organic peroxide-based initiator as the radical polymerization initiator used when radically polymerizing ethylene and a vinyl ester monomer)
Examples of the azonitrile-based initiator include 2,2-azobisisobutyronitrile, 2,2-azobis- (2,4-dimethylvaleronitrile), and 2,2-azobis- (4-methoxy-2,4-). Dimethylvaleronitrile), 2,2-azobis- (2-cyclopropylpropionitrile) and the like. Examples of the organic peroxide include acetyl peroxide, isobutyl peroxide, diisopropyl peroxy carbonate, diallyl peroxy dicarbonate, di-n-propyl peroxy dicarbonate, dimyristyl peroxy dicarbonate, and di (2-ethoxyethyl). ) Peroxydicarbonate, di (2-ethylhexyl) peroxydicarbonate, di (methoxyisopropyl) peroxydicarbonate, di (4-tert-butylcyclohexyl) peroxydicarbonate and the like.

((H) In the preparation of a copolymer of ethylene and vinyl ester as a raw material, the amount added when a radical polymerization inhibitor is added after radical polymerization is set to a specific amount with respect to the remaining undecomposed radical polymerization initiator. how to)
When a radical polymerization inhibitor is added after radical polymerization, the amount added is preferably 5 molar equivalents or less with respect to the remaining undecomposed radical polymerization initiator. Examples of the radical polymerization inhibitor include compounds having a conjugated double bond and having a molecular weight of 1,000 or less, which stabilize radicals and inhibit the polymerization reaction. Specific examples of the radical polymerization inhibitor include isoprene, 2,3-dimethyl-1,3-butadiene, 2,3-diethyl-1,3-butadiene, 2-t-butyl-1,3-butadiene, 1 , 3-Pentadiene, 2,3-dimethyl-1,3-Pentadiene, 2,4-dimethyl-1,3-Pentadiene, 3,4-dimethyl-1,3-Pentadiene, 3-Ethyl-1,3-Pentadiene , 2-Methyl-1,3-Pentadiene, 3-Methyl-1,3-Pentadiene, 4-Methyl-1,3-Pentadiene, 1,3-Hexadiene, 2,4-Hexadiene, 2,5-dimethyl-2 , 4-Hexadien, 1,3-octadien, 1,3-Cyclopentadiene, 1,3-Cyclohexadiene, 1-methoxy-1,3-butadiene, 2-methoxy-1,3-butadiene, 1-ethoxy-1 , 3-butadiene, 2-ethoxy-1,3-butadiene, 2-nitro-1,3-butadiene, piperylene, 1-chloro-1,3-butadiene, 1-bromo-1,3-butadiene, 2-bromo Conjugated structure of two carbon-carbon double bonds such as -1,3-butadiene, fluben, tropone, osimene, ferlandrene, milsen, farnesene, sembrylene, sorbic acid, sorbic acid ester, sorbate, avietic acid, etc. Conjugated Diene Containing; Containing 3 Carbon-Carbon Double Bonds such as 1,3,5-Hexatriene, 2,4,6-octatorylene-1-carboxylic Acid, Eleostearic Acid, Tung Oil, Cholecalciferol, etc. Conjugated Triene Containing Conjugated Structure; Conjugated Polyene Containing Conjugated Structure of Four or More Carbon-Carbon Double Bonds such as Cyclooctatetraene, 2,4,6,8-Decatetraene-1-carboxylic Acid, Retinol, Retinonic Acid Such as piperylene can be mentioned. Any of these may be used for those having a plurality of stereoisomers such as 1,3-pentadiene, myrcene, farnesene and the like. Examples of the radical polymerization inhibitor include p-benzoquinone, hydroquinone, hydroquinone monomethyl ether, 2-phenyl-1-propene, 2-phenyl-1-butene, 2,4-diphenyl-4-methyl-1-pentene, 3, 5-diphenyl-5-methyl-2-heptene, 2,4,6-triphenyl-4,6-dimethyl-1-heptene, 3,5,7-triphenyl-5-ethyl-7-methyl-2- Nonen, 1,3-diphenyl-1-butene, 2,4-diphenyl-4-methyl-2-pentene, 3,5-diphenyl-5-methyl-3-heptene, 1,3,5-triphenyl-1 -Hexen, 2,4,6-triphenyl-4,6-dimethyl-2-heptene, 3,5,7-triphenyl-5-ethyl-7-methyl-3-nonene, 1-phenyl-1,3 Aromatic compounds such as −butadiene, 1,4-diphenyl-1,3-butadiene are also included.

((I) A method of using an alcohol solution of a copolymer of ethylene and vinyl ester from which residual vinyl ester has been removed as much as possible for a saponification reaction)
The lower limit of the removal rate of the residual monomer is preferably 99 mol%, more preferably 99.5 mol%, still more preferably 99.8 mol%. Examples of the method for removing the residual monomer include a method using column chromatography, a reprecipitation method, a distillation method, and the like, and the distillation method is preferable. When removing residual monomers by the distillation method, a copolymer solution of ethylene and vinyl ester is continuously supplied at a constant rate from the upper part of the distillation column filled with Raschig ring, and organic solvent vapor such as methanol is supplied from the lower part of the distillation column. Blow in. As a result, the mixed vapor of the organic solvent and the unreacted vinyl ester can be distilled off from the top of the distillation column, and a copolymer solution of ethylene and vinyl ester from which the unreacted vinyl ester has been removed from the bottom of the distillation column. Can be taken out. Here, the "remaining monomer removal rate" is a value calculated by the following formula by measuring the monomer content of the alcohol solution of the copolymer of ethylene and vinyl ester before and after the removal treatment.
Removal rate of residual monomer (mol%) = {1- (residual monomer content after removal / residual monomer content before removal)} x 100

((J) Method of adding an antioxidant to the copolymer of ethylene and vinyl ester used for saponification)
The antioxidant is not particularly limited, and examples thereof include a phenol-based antioxidant, a phosphorus-based antioxidant, and a sulfur-based antioxidant. Among these, as the antioxidant, a phenolic antioxidant is preferable, and an alkyl-substituted phenolic antioxidant is more preferable.

Examples of the phenolic antioxidant include 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenylacrylate and 2,4-di-t-amyl-. An acrylate compound such as 6- (1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl) phenyl acrylate; 2,6-di-t-butyl-4-methylphenol, 2,6- Di-t-butyl-4-ethylphenol, octadecyl-3- (3,5-) di-t-butyl-4-hydroxyphenyl) propionate, 2,2'-methylene-bis (4-methyl-6-t) -Butylphenol), 4,4'-butylidene-bis (4-methyl-6-t-butylphenol), 4,4'-butylidene-bis (6-t-butyl-m-cresol), 4,4'-thiobis (3-Methyl-6-t-butylphenol), bis (3-cyclohexyl-2-hydroxy-5-methylphenyl) methane, 3,9-bis (2- (3- (3-t-butyl-4-hydroxy) -5-Methylphenyl) propionyloxy) -1,1-dimethylethyl) -2,4,8,10-tetraoxaspiro [5.5] undecane, 1,1,3-tris (2-methyl-4-4) Hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis (methylene-3-3) (3', 5'-di-t-butyl-4'-hydroxyphenyl) propionate) Methane, triethylene glycolbis (3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate), etc. Alkyl-substituted phenolic compounds; 6- (4-hydroxy-3,5-di-t-butylanilino) -2,4-bis-octylthio-1,3,5-triazine, 6- (4-hydroxy-3,5) -Dimethylanilino) -2,4-bis-octylthio-1,3,5-triazine, 6- (4-hydroxy-3-methyl-5-t-butylanilino) -2,4-bis-octylthio-1, Examples thereof include triazine group-containing phenolic compounds such as 3,5-triazine and 2-octylthio-4,6-bis- (3,5-di-t-butyl-4-oxyanilino) -1,3,5-triazine. Be done.

Examples of phosphorus-based antioxidants include triphenylphosphite, diphenylisodecylphosphite, phenyldiisodecylphosphite, tris (nonylphenyl) phosphite, tris (dinonylphenyl) phosphite, and tris (2-t-butyl-). 4-Methylphenyl) phosphite, tris (cyclohexylphenyl) phosphite, 2,2-methylenebis (4,6-di-t-butylphenyl) octylphosphite, 9,10-dihydro-9-oxa-10-phos Phenyl10-oxide, 10- (3,5-di-t-butyl-4-hydroxybenzyl) -9,10-dihydro-9-oxa-10-phosphaphenylanthrene-10-oxide, 10-decyloxy- Monophosphite compounds such as 9,10-dihydro-9-oxa-10-phosphaphenantrene; 4,4'-butylidene-bis (3-methyl-6-t-butylphenyl-ditridecylphosphite), 4 , 4'-isopropylidene-bis (phenyl-dialkyl (12 to 15 carbon atoms) phosphite), 4,4'-isopropylidene-bis (diphenylmonoalkyl (12 to 15 carbon atoms) phosphite), 1,1 , 3-Tris (2-methyl-4-ditridecylphosphite-5-t-butylphenyl) butane, tetrakis (2,4-di-t-butylphenyl) -4,4'-biphenylene phosphite and other diphosphite Examples include system compounds. Among these, the phosphorus-based antioxidant is preferably a monophosphite-based compound.

Examples of the sulfur-based antioxidant include dilauryl 3,3'-thiodipropionate, distearyl 3,3'-thiodipropionate, laurylstearyl 3,3'-thiodipropionate, and pentaerythritol-tetrakis- (. β-lauryl-thiopropionate), 3,9-bis (2-dodecylthioethyl) -2,4,8,10-tetraoxaspiro [5.5] undecane and the like.

When an antioxidant is added to the copolymer of ethylene and vinyl ester, the lower limit of the content of the antioxidant is not particularly limited, but is 0.001 part by mass with respect to 100 parts by mass of the copolymer. Is preferable, and 0.01 part by mass is more preferable. On the other hand, the upper limit of the content of the antioxidant is not particularly limited, but is preferably 5 parts by mass and more preferably 1 part by mass with respect to 100 parts by mass of the copolymer. If the content of the antioxidant is less than the above lower limit, it may be difficult to prepare EVOH (A) satisfying the formula (1). On the contrary, if the content of the antioxidant exceeds the above upper limit, the effect corresponding to the cost increase due to the increase in the content may not be obtained.

When EVOH (A) is prepared by the methods (A), (C) to (J) above, the content of acetaldehyde contained in the vinyl ester (vinyl acetate) does not have to be in the above range. The lower limit of the acetaldehyde content in this case is preferably 150 ppm, more preferably 250 ppm, and even more preferably 350 ppm. By setting the content of acetaldehyde in the above range in this way, the step of removing acetaldehyde from vinyl acetate can be omitted, so that the production cost can be reduced. The upper limit of the acetaldehyde content in this case is not particularly limited, but is, for example, 1,000 ppm.

(Melting viscosity of EVOH (A) (melt flow rate))
The lower limit of the melt flow rate of EVOH (A) is preferably 0.5 g / 10 min, more preferably 1.0 g / 10 min, and even more preferably 1.4 g / 10 min. On the other hand, as the upper limit of the melt flow rate of EVOH (A), 30 g / 10 min is preferable, 25 g / 10 min is more preferable, 20 g / 10 min is further preferable, 15 g / 10 min is particularly preferable, and 10 g / 10 min is further particularly preferable. Most preferably 1.6 g / 10 min. If the melt flow rate of EVOH (A) is less than the above lower limit, or if it exceeds the above upper limit, the moldability and appearance characteristics may deteriorate.

The melt flow rate is a value measured at a temperature of 190 ° C. and a load of 2,160 g in accordance with JIS-K7210: 1999.

[Inorganic particles (B)]
The inorganic particles (B) have an appropriate arithmetic mean roughness (Ra) on the surface of the film formed from the resin composition, and improve blocking resistance and slipperiness. Here, the inorganic particles (B) refer to particles containing an inorganic substance as a main component.

As the metal element constituting the inorganic particles (B), at least one selected from the group consisting of silicon, aluminum, magnesium, zirconium, cerium, tungsten and molybdenum is preferable. Among these, at least one selected from the group consisting of silicon, aluminum and magnesium is more preferable as the metal element because it is easily available.

Examples of the inorganic substance that is the main component of the inorganic particles (B) include oxides, nitrides, and oxide nitrides of the metal elements exemplified, and oxides are preferable.

The lower limit of the average particle size of the inorganic particles (B) is preferably 0.5 μm, more preferably 1.5 μm, and even more preferably 2.5 μm. The upper limit of the average particle size of the inorganic particles (B) is preferably 10 μm, more preferably 8 μm, further preferably 5 μm, and particularly preferably 3 μm. By setting the average particle size of the inorganic particles (B) in the above range, the arithmetic average roughness (Ra) of the surface of the film formed from the resin composition becomes appropriate, and the blocking resistance and slipperiness are improved. To do. As a result, the resin composition can improve the film breaking resistance, the film deposition defect suppressing property, and the adhesion strength of the vapor deposition layer, and can further improve the adhesion strength of the film. Here, the "average particle size of the inorganic particles (C)" is a particle size distribution (particle size and relative particles) calculated from light intensity distribution data of diffracted / scattered light measured using a laser diffraction type particle size distribution measuring device. Amount) is used to divide the integrated value of the value obtained by multiplying the particle size and the relative particle amount by the total relative particle amount.

The lower limit of the content of the inorganic particles (B) is preferably 50 ppm, more preferably 100 ppm, and even more preferably 150 ppm. The upper limit of the content of the inorganic particles (B) is preferably 5,000 ppm, more preferably 4,000 ppm, further preferably 3,000 ppm, particularly preferably 1,000 ppm, and even more preferably 200 ppm. By setting the content of the inorganic particles (B) in the above range, the arithmetic average roughness (Ra) of the surface of the film formed from the resin composition becomes appropriate, and the blocking resistance and slipperiness are improved. .. As a result, the film breaking resistance and the film deposition defect suppressing property of the resin composition can be further improved, and the adhesion strength of the obtained film can be improved. In addition, the inorganic particle (B) may have one particle formed of one kind or two or more kinds of inorganic substances.

[Alkali metal salt (C)]
The alkali metal constituting the alkali metal salt (C) may be a single metal species or may be composed of a plurality of metal species. Examples of the alkali metal include lithium, sodium, potassium, rubidium, cesium and the like, but sodium and potassium are more preferable from the viewpoint of industrial availability. When the resin composition contains the alkali metal salt (C), the long-running property and the interlayer adhesive strength when formed into a multilayer structure are improved.

Examples of the anion constituting the alkali metal salt (C) include an anion of an organic acid. Examples of the organic acid include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, heptic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, palmitic acid, stearic acid, succinic acid, linoleic acid and oleic acid. And other aliphatic carboxylic acids; aromatic carboxylic acids such as benzoic acid, salicylic acid and phthalic acid; hydroxycarboxylic acids such as lactic acid, tartaric acid, citric acid and malic acid; carboxylic acids such as ethylenediamine tetraacetic acid and p-toluenesulfonic acid and the like. Sulfonic acid and the like. Among these, as the organic acid, a carboxylic acid is preferable, an aliphatic carboxylic acid is more preferable, and acetic acid is further preferable.

The alkali metal salt (C) is not particularly limited, and examples thereof include aliphatic carboxylic acid salts such as lithium, sodium, and potassium, aromatic carboxylic acid salts, phosphates, and metal complexes. Specific alkali metal salts (C) include, for example, sodium acetate, potassium acetate, sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, lithium dihydrogen phosphate, trilithium phosphate, sodium stearate. , Potassium stearate, sodium salt of ethylenediamine tetraacetic acid and the like. As the alkali metal salt (C), an alkali metal salt of an organic acid is preferable, and sodium acetate and potassium acetate are more preferable.

When the resin composition contains an alkali metal salt, the lower limit of the alkali metal salt content (content in the dry resin composition) is preferably 1 ppm, more preferably 5 ppm, and further 10 ppm in terms of metal. Preferably, 80 ppm is particularly preferable. On the other hand, the upper limit of the content of the alkali metal salt is preferably 1,000 ppm, more preferably 800 ppm, further preferably 550 ppm, particularly preferably 250 ppm, and even more preferably 150 ppm in terms of metal. If the content of the alkali metal salt is less than the above lower limit, the interlayer adhesiveness may decrease. On the contrary, if the content of the alkali metal salt exceeds the above upper limit, it becomes difficult to reduce the coloring of the resin composition, and the appearance characteristics may be deteriorated.

[Other optional ingredients]
Other optional components include, for example, antioxidants, UV absorbers, plastics, antistatic agents, lubricants, colorants, fillers, polyvalent metal salts of higher aliphatic carboxylic acids, hindered phenolic compounds and hindered amines. Examples thereof include heat stabilizers such as compounds, other resins such as polyamide and polyolefin, and hydrotalcite compounds. The total content of other optional components of the resin composition is usually 1% by mass or less.

Examples of the filler include glass fiber, ballast night, calcium silicate, talc, montmorillonite and the like.

Examples of the polyvalent metal salt of the higher aliphatic carboxylic acid include calcium stearate and magnesium stearate.

As a measure against gelation, for example, a hindered phenol-based compound and a hindered amine-based compound exemplified as the above-mentioned heat stabilizer, a polyvalent metal salt of the above-mentioned higher aliphatic carboxylic acid, a hydrotalcite compound and the like are added to the resin composition. You may. When a compound for preventing gelation is added to the resin composition, the amount of the compound added is usually 0.01% by mass or more and 1% by mass or less.

[Melting viscosity of resin composition (melt flow rate)]
The lower limit of the melt flow rate of the resin composition is preferably 0.5 g / 10 min, more preferably 1.0 g / 10 min, and even more preferably 1.4 g / 10 min. On the other hand, the upper limit of the melt flow rate of the resin composition is preferably 30 g / 10 min, more preferably 25 g / 10 min, further preferably 20 g / 10 min, particularly preferably 15 g / 10 min, still more preferably 10 g / 10 min. Most preferably 1.6 g / 10 min. If the melt flow rate of the resin composition is less than the above lower limit, or if it exceeds the above upper limit, the moldability and appearance may be deteriorated.

<Manufacturing method of resin composition>
The method for producing the resin composition is particularly limited as long as it is a method capable of uniformly blending, for example, EVOH (A) and inorganic particles (B) together with an alkali metal salt (C) and other optional components as needed. Not done.

As a method of uniformly blending the inorganic particles (B) and the like in the resin composition,
In the step of (1) copolymerizing ethylene and vinyl ester in the method for producing an ethylene-vinyl alcohol copolymer, and (2) the step of saponifying the copolymer obtained in step (1), for example, the above. Method of adding inorganic particles (B) or the like in step (1),
A method of adding inorganic particles (B) or the like in the above step (2),
A method of adding inorganic particles (B) or the like to EVOH obtained in the above step (2).
A method of adding inorganic particles (B) or the like when melt-molding the EVOH obtained in the above step (2).
Examples include a method in which these methods are used in combination.

When the method of adding the inorganic particles (B) or the like in the above step (1) or the method of adding the inorganic particles (B) or the like in the above step (2) is adopted, the polymerization reaction in the above step (1) , It is necessary to add these in a range that does not inhibit the saponification reaction in the above step (2).

Among these methods, from the viewpoint of easiness of adjusting the content of the inorganic particles (B) and the like in the resin composition, a method of adding the inorganic particles (B) and the like to the EVOH obtained in the step (2), and A method of adding inorganic particles (B) or the like when melt-molding the EVOH obtained in the step (2) is preferable, and a method of adding the inorganic particles (B) or the like to the EVOH obtained in the step (2) is more preferable. preferable.

Examples of the method of adding the inorganic particles (B) or the like to the resin composition include a method of blending the inorganic particles (B) and the like with EVOH in advance to granulate pellets, and a method of redissolving the chips of the dry resin composition. A method of adding inorganic particles (B) or the like to the mixture, a method of melt-kneading a blend of EVOH (A), inorganic particles (B), etc., and a method of melt-kneading the melt of EVOH (A) from the middle of the extruder. ) Etc., a master batch prepared by blending inorganic particles (B) and the like in a part of EVOH (A) at a high concentration, and dry-blending this master batch and EVOH (A). And the method of melting and kneading.

Of these, from the viewpoint that the inorganic particles (B) and the like can be more uniformly dispersed in the EVOH (A), a method in which the inorganic particles (B) and the like are mixed with EVOH in advance to granulate pellets is preferable. Specifically, inorganic particles (B) are added to a solution in which EVOH (A) is dissolved in a good solvent such as a water / methanol mixed solvent, and the mixed solution is extruded from a nozzle or the like into a poor solvent for precipitation and precipitation. / Or by coagulating, washing and / or drying it, pellets in which the inorganic particles (B) and the like are uniformly mixed with EVOH (A) can be obtained.

Examples of the method of incorporating the other components other than the inorganic particles (B) into the resin composition include a method of mixing the pellets together with each component and melt-kneading them, and when preparing the pellets, the inorganic particles (B). ) Etc., a method of mixing other components, a method of immersing the pellet in a solution containing each component, and the like. A ribbon blender, a high-speed mixer conider, a mixing roll, an extruder, an intensive mixer, or the like can be used for mixing the pellets with other components.

The resin composition is molded into various molded bodies such as films, sheets, containers, pipes, and fibers by melt molding or the like. Here, the film usually means a film having an average thickness of less than about 300 μm, and the sheet usually means a film having an average thickness of about 300 μm or more. Examples of the melt molding method include extrusion molding, cast molding, inflation extrusion molding, blow molding, melt spinning, injection molding, injection blow molding and the like. The melt molding temperature varies depending on the melting point of EVOH (A) and the like, but is preferably about 150 ° C. or higher and 270 ° C. or lower. Since the molded product is formed from the resin composition described above, it has excellent appearance characteristics. These compacts can also be crushed and remolded for reuse. It is also possible to uniaxially or biaxially stretch a film, sheet, fiber or the like. The molded product obtained by the above-mentioned melt molding or the like may be subjected to secondary processing molding such as bending, vacuum forming, blow molding, press molding or the like to obtain a desired molded product, if necessary.

<Film>
The film is formed from the resin composition. Since the film is formed from the resin composition, it is excellent in appearance characteristics and film breakage resistance. The film includes a single-layer film and a multilayer film.

The lower limit of the arithmetic mean roughness (Ra) of at least one surface of the film measured in accordance with JIS-B0601: 2001 is preferably 0.05 μm, more preferably 0.10 μm, and further 0.15 μm. Preferably, 0.20 μm is particularly preferable. The upper limit of the arithmetic mean roughness (Ra) of at least one surface of the film is preferably 1.0 μm, more preferably 0.8 μm, further preferably 0.6 μm, and particularly preferably 0.4 μm. By setting the arithmetic mean roughness (Ra) of at least one surface of the film within the above range, the film breakability can be further improved.

The lower limit of the average length (RSm) of the contour curve element of at least one surface of the film measured in accordance with JIS-B0601: 2001 is preferably 50 μm, more preferably 100 μm, further preferably 150 μm, and even more preferably 200 μm. Is particularly preferable. The upper limit of the average length (RSm) of the contour curve elements on at least one surface of the film is preferably 1,000 μm, more preferably 800 μm, even more preferably 600 μm, and particularly preferably 400 μm. By setting the average length (RSm) of the contour curve elements on at least one surface of the film within the above range, the film breakability can be further improved.

<Film manufacturing method>
Examples of the method for producing the film include a cast molding step of melt-extruding the resin composition onto a casting roll, and a step of stretching an unstretched film obtained from the resin composition in this cast molding step (uniaxial stretching step, sequentially). A method having a biaxial step, a simultaneous biaxial stretching step, an inflation forming step, etc.) can be mentioned. By producing the film by the production method having the above-mentioned steps, the film breakability can be further improved.

<Multi-layer structure>
The multilayer structure has a plurality of layers, and at least one of the plurality of layers is the film (hereinafter, also referred to as “barrier layer”). Examples of such a multilayer structure include a multilayer sheet, a multilayer pipe, a multilayer hose, a multilayer fiber and the like.

Examples of the plurality of layers included in the multilayer structure include a thermoplastic resin layer formed from a thermoplastic resin, a layer obtained from an adhesive resin, a metal vapor deposition layer, and the like.

The method for producing the multilayer structure is not particularly limited, and for example, a method of melt-extruding a thermoplastic resin, an adhesive resin, or the like onto the film, or a method of co-extruding the resin composition with another thermoplastic resin. , A method of co-injecting the resin composition and the thermoplastic resin, and the barrier layer or multilayer structure obtained from the resin composition and a film, sheet or the like of another base material are combined with an organic titanium compound, an isocyanate compound, or a polyester. Examples thereof include a method of laminating using a known adhesive such as a system compound.

Further, in the multilayer structure, it is also preferable that at least one of the plurality of layers is a metal vapor deposition layer. Further, in the multilayer structure, another resin layer may be laminated on the surface on the metal vapor deposition layer side and / or the opposite side. When the multilayer structure is provided with the layer metal vapor deposition layer or another resin layer, gas barrier properties and moisture resistance can be enhanced. Further, since the multilayer structure uses a film formed from the above-mentioned resin composition, there are few vapor deposition defects and the adhesion strength between the metal vapor deposition layer and the EVOH film layer is excellent.

Examples of the thermoplastic resin used for the layer composed of other components in the multilayer structure include linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, and ethylene-propylene. Copolymer, polypropylene, propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymer, olefin alone or copolymer such as polybutene and polypentene, polyester such as polyethylene terephthalate, polyester elastomer, nylon Examples thereof include polyamides such as -6 and nylon-66, polystyrene, polyvinyl chloride, polyvinylidene chloride, acrylic resins, vinyl ester resins, polyurethane elastomers, polycarbonates, chlorinated polyethylenes, and chlorinated polypropylenes. Among these, polypropylene, polyethylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, polyamide, polystyrene and polyester are preferable as the thermoplastic resin.

The adhesive resin is not particularly limited as long as it has adhesiveness to the resin composition and the thermoplastic resin, but an adhesive resin containing a carboxylic acid-modified polyolefin is preferable. The carboxylic acid-modified polyolefin is a modified olefin containing a carboxy group obtained by chemically (for example, addition reaction, graft reaction, etc.) binding an ethylenically unsaturated carboxylic acid, an ester thereof, or an anhydride thereof to an olefin polymer. A system polymer can be preferably used. Here, the olefin polymer includes polyolefins such as polyethylene (low pressure, medium pressure, high pressure, etc.), linear low density polyethylene, polypropylene, boribten, olefins and other monomers (vinyl ester, unsaturated carboxylic acid ester). Etc.) and copolymers (for example, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ethyl ester copolymer, etc.) are also included. Among these, the carboxylic acid-modified polyolefin includes linear low-density polyethylene, ethylene-vinyl acetate copolymer (vinyl acetate content is 5% by mass or more and 55% by mass or less), and ethylene-acrylic acid ethyl ester. A polymer (content of ethyl acrylate ester is 8% by mass or more and 35% by mass or less) is preferable, and a linear low-density polyethylene and an ethylene-vinyl acetate copolymer are more preferable. The ethylenically unsaturated carboxylic acid, its ester and its anhydride include ethylenically unsaturated monocarboxylic acid and its ester, ethylenically unsaturated dicarboxylic acid and its mono or diester, ethylenically unsaturated monocarboxylic acid anhydride, and ethylene. Examples thereof include sex-unsaturated dicarboxylic acid anhydrides, and among these, ethylenically unsaturated dicarboxylic acid anhydrides are preferable. Specific ethylenically unsaturated dicarboxylic acid anhydrides include maleic acid, fumaric acid, itaconic acid, maleic anhydride, itaconic anhydride, maleic acid monomethyl ester, maleic acid monoethyl ester, maleic acid diethyl ester, and monomethyl fumarate. Examples thereof include esters, and maleic anhydride is particularly preferable.

The lower limit of the amount of ethylenically unsaturated carboxylic acid or its anhydride added to the olefin polymer or the amount of graft (modification) is preferably 0.0001% by mass, preferably 0.001% by mass, based on the olefin polymer. Is more preferable. On the other hand, the upper limit of the degree of modification is preferably 15% by mass, more preferably 10% by mass or less. The addition reaction or graft reaction of ethylenically unsaturated carboxylic acid or its anhydride to an olefin-based polymer shall be carried out by, for example, a radical polymerization method in the presence of a solvent (xylene or the like) or a catalyst (peroxide or the like). Can be done.

The lower limit of the melt flow rate (MFR) of the carboxylic acid-modified polyolefin thus obtained measured at 210 ° C. is preferably 0.2 g / 10 minutes, more preferably 0.5 g / 10 minutes. On the other hand, the upper limit of the MFR is preferably 30 g / 10 minutes, more preferably 10 g / 10 minutes.

The coextrusion method of the resin composition and the thermoplastic resin or the like is not particularly limited, and examples thereof include a multi-manifold merging method T-die method, a feed block merging method T-die method, and an inflation method.

[Metal vapor deposition layer]
The metal vapor deposition layer mainly secures gas barrier properties in the multilayer structure.

Examples of the material for forming the metal vapor deposition layer include aluminum, silicon, magnesium, zinc, tin, nickel, titanium, one or more of these oxides, carbides, nitrides, and the like. It is preferable to use aluminum alone or in combination. By using aluminum in this way, it is possible to obtain a thin-film vapor-deposited film that is light and has high flexibility and gloss.

The lower limit of the total average thickness of the metal vapor deposition layers is preferably 30 nm, more preferably 35 nm, and even more preferably 40 nm. The upper limit of the total average thickness of the metal vapor deposition layer is preferably 150 nm, more preferably 140 nm, further preferably 130 nm, and particularly preferably 70 nm. If the total average thickness of the metal vapor deposition layers is less than the above lower limit, the gas barrier property may be insufficient. On the other hand, if the total average thickness of the metal vapor deposition layers exceeds the above upper limit, heat bridging is likely to occur, and the heat insulating effect may be reduced.

Here, the average thickness of the metal-deposited layer is an average value of the thicknesses at any 10 points of the metal-deposited layer cross section measured by an electron microscope.

The lower limit of the average particle size of the vapor-deposited particles such as aluminum particles in the metal vapor-deposited layer is not particularly limited, but is preferably 10 nm, more preferably 15 nm, and even more preferably 20 nm. The upper limit of the average particle size of the vapor-deposited particles is preferably 150 nm, more preferably 125 nm, further preferably 100 nm, particularly preferably 75 nm, and most preferably 50 nm.

Here, the average particle diameter of the vapor-deposited particles is obtained by observing the surface of the metal-deposited layer with a scanning electron microscope and measuring the total value of the maximum diameters (maximum diameters in a fixed direction) of a plurality of vapor-deposited particles existing in the same direction by the number of measured particles. Means the average value divided. Further, the average particle diameter means the particle diameter (primary particle diameter) of the vapor-deposited particles constituting the granules when the vapor-deposited particles are formed of agglomerates.

The layer structure of the multilayer structure is not particularly limited, but the layer composed of the barrier layer is E, the metal vapor deposition layer is M, the layer obtained from the adhesive resin is Ad, and the layer obtained from the thermoplastic resin is T. When represented, structures such as T / E / T, E / Ad / T, T / Ad / E / Ad / T, and M / T / Ad / E / Ad / T can be mentioned. Among these, as the layer structure of the multilayer structure, a layer structure in which the metal vapor deposition layer is the outermost layer is preferable. In addition, each layer of the said layer structure may be a single layer or may be a multi-layer.

<Packaging material>
The packaging material comprises the multilayer structure. By providing the multi-layer structure, the packaging material has excellent gas barrier properties, and the gas barrier properties are maintained even when subjected to physical stress such as deformation or impact.

The packaging material is formed by laminating at least one layer of the film and at least one other layer. Examples of other layers include a polyester layer, a polyamide layer, a polyolefin layer, a paper layer, an inorganic thin-film film layer, an EVOH layer, an adhesive layer and the like. The number of layers and the order of lamination in the packaging material are not particularly limited, but when heat sealing is performed, at least the outermost layer is a layer capable of heat sealing. The polyolefin layer may contain a pigment when the packaging material is configured as a laminated tube container or the like described later.

The packaging material is used for packaging, for example, foods, beverages, chemicals such as pesticides and pharmaceuticals, medical equipment, mechanical parts, industrial materials such as precision materials, and clothing. In particular, the packaging material is preferably used for applications that require a barrier property against oxygen and applications in which the inside of the packaging material is replaced by various functional gases.

The packaging material is formed in various forms depending on the application, for example, a vertical bag filling seal bag, a vacuum packaging bag, a pouch with a spout, a laminated tube container, a lid material for a container, and the like.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples.

[Synthesis of EVOH]
[Synthesis Example 1] (Synthesis of EVOH pellets)
(Polymerization of ethylene-vinyl acetate copolymer)
83 kg of vinyl acetate and 14.9 kg of methanol (hereinafter referred to as MeOH) were charged in a 250 L pressure reaction tank equipped with a jacket, a stirrer, a nitrogen inlet, an ethylene inlet and an initiator addition port, and the temperature was raised to 60 ° C. After that, nitrogen gas was bubbled into the reaction solution for 30 minutes to replace the inside of the reaction vessel with nitrogen. Next, ethylene was introduced so that the reaction vessel pressure (ethylene pressure) was 4.0 MPa. After adjusting the temperature in the reaction vessel to 60 ° C., use 12.3 g of 2,2'-azobis (2,4-dimethylvaleronitrile) ("V-65" from Wako Pure Chemical Industries, Ltd.) as an initiator. It was added as a methanol solution to initiate polymerization. During the polymerization, the ethylene pressure was maintained at 4.0 MPa and the polymerization temperature was maintained at 60 ° C. After 5 hours, when the polymerization rate of vinyl acetate reached 40%, the mixture was cooled to terminate the polymerization. Ethylene was exhausted from the reaction vessel, and nitrogen gas was bubbled into the reaction solution to completely remove ethylene. Then, after removing unreacted vinyl acetate under reduced pressure, an ethylene-vinyl acetate copolymer (hereinafter referred to as EVAc) was obtained. As the vinyl acetate used for the synthesis, acetaldehyde having the content shown in Table 1 was added.

(Ken)
Methanol was added to the obtained EVAc solution to obtain a methanol solution of EVAc having a concentration of 15% by mass. To 253.4 kg of a methanol solution of EVAc (38 kg of EVAc in the solution), 76.6 L of a methanol solution containing 10% by mass of sodium hydroxide (molar ratio 0.4 to vinyl acetate unit in EVAc) was added. EVAc was saponified by stirring at 60 ° C. for 4 hours. Six hours after the start of the reaction, 9.2 kg of acetic acid and 60 L of water were added to neutralize the reaction solution, and the reaction was stopped.

(Washing)
The neutralized reaction solution was transferred from the reactor to a drum can and left at room temperature for 16 hours to cool and solidify into a cake. Then, the cake-shaped resin was deflated using a centrifuge (“H-130” manufactured by Japan Centrifuge Co., Ltd., rotation speed 1200 rpm). Next, the central portion of the centrifuge was washed while continuously supplying ion-exchanged water from above, and the above resin was washed with water for 10 hours. The conductivity of the cleaning liquid 10 hours after the start of cleaning was 30 μS / cm (measured with “CM-30ET” of Toa Denpa Kogyo Co., Ltd.).

(Granulation)
The powdery EVOH thus obtained was dried at 60 ° C. for 48 hours using a dryer. 20 kg of dried powdery EVOH was put into 43 L of a mixed solution of water and methanol (mass ratio: water / methanol = 4/6), and dissolved by stirring at 80 ° C. for 12 hours. Next, the stirring was stopped, the temperature of the dissolution tank was lowered to 65 ° C., and the mixture was left to stand for 5 hours to defoam the above-mentioned EVOH water and methanol solution. Then, it is extruded from a gold plate having a circular opening with a diameter of 3.5 mm into a mixed solution of water and methanol at 5 ° C. (mass ratio: water / methanol = 9/1) to precipitate in a strand shape and cut. A hydrous EVOH pellet having a diameter of about 4 mm and a length of about 5 mm was obtained.

(purification)
The obtained hydrous EVOH pellets were deliquesed with a centrifuge, and the operation of adding a large amount of water to deliquidate was repeated to wash the obtained pellets of EVOH. The degree of saponification of the obtained EVOH was 99 mol%.

[Synthesis Examples 2-4 and Comparative Synthesis Example 1]
EVOH was synthesized in the same manner as in Synthesis Example 1 except that the acetaldehyde content of vinyl acetate, the saponification degree of EVOH (A), and the content of the alkali metal salt were as shown in Table 1.

Using the obtained dried EVOH pellets, the saponification degree, ethylene content, alkali metal content and the like of EVOH shown in Table 1 were measured by the method described below.

[Ethylene content and saponification of EVOH]
The dried EVOH pellets were pulverized by freeze milling. The obtained pulverized EVOH was sieved with a sieve having a nominal size of 1 mm (standard flue standard JIS-Z8801 compliant). 5 g of EVOH powder that had passed through this sieve was immersed in 100 g of ion-exchanged water, stirred at 85 ° C. for 4 hours, and then deliquesed and dried twice. Using the obtained powdered EVOH after washing, ¹ H-NMR measurement was carried out under the following measurement conditions, and the ethylene content and the degree of saponification were determined by the following analysis method.

(Measurement condition)
Device name: Superconducting nuclear magnetic resonance device ("Lambda500" from JEOL Ltd.)
Observation frequency: 500MHz
Solvent: DMSO-d ₆
Polymer concentration: 4% by mass
Measurement temperature: 40 ° C and 95 ° C
Number of integrations: 600 Pulse delay time: 3.836 seconds Sample rotation speed: 10Hz to 12Hz
Pulse width (90 ° pulse): 6.75 μsec

(analysis method)
In the measurement at 40 ° C., a hydrogen peak in the water molecule was observed around 3.3 ppm, which overlapped with the 3.1 ppm to 3.7 ppm portion of the peak of methine hydrogen in vinyl alcohol units of EVOH. On the other hand, in the measurement at 95 ° C., although the overlap generated at 40 ° C. is eliminated, the hydrogen peak of the hydroxyl group of the vinyl alcohol unit of EVOH present in the vicinity of 4 ppm to 4.5 ppm is the methine of the vinyl alcohol unit of EVOH. It overlapped with the 3.7 ppm to 4 ppm portion of the hydrogen peak. That is, for the quantification of methine hydrogen (3.1 ppm to 4 ppm) in vinyl alcohol units of EVOH, 95 for the portion of 3.1 ppm to 3.7 ppm in order to avoid duplication with the hydrogen peak of water or hydroxyl group. The measurement data at ° C. was adopted, and the measurement data at 40 ° C. was adopted for the portion of 3.7 ppm to 4 ppm, and the total amount of the methine hydrogen was quantified as the total value of these. It is known that the peak of hydrogen of water or a hydroxyl group shifts to the high magnetic field side by raising the measurement temperature. Therefore, the analysis was performed using the measurement results of both 40 ° C. and 95 ° C. as follows. From the above spectrum measured at 40 ° C., the integrated value (I ₁ ) of the peak of the chemical shift of 3.7 ppm to 4 ppm and the integrated value (I ₂ ) of the peak of the chemical shift of 0.6 ppm to 1.8 ppm were obtained. ..

On the other hand, from the spectrum measured at 95 ° C., the integrated value of the chemical shift peak of 3.1 ppm to 3.7 ppm (I ₃ ), the integrated value of the peak of the chemical shift of 0.6 ppm to 1.8 ppm (I ₄ ), and The integral value (I ₅ ) of the peak of the chemical shift of 1.9 ppm to 2.1 ppm was determined. Here, the peak of the chemical shift of 0.6 ppm to 1.8 ppm is mainly derived from methylene hydrogen, and the peak of the chemical shift of 1.9 ppm to 2.1 ppm is in the unsaken vinyl acetate unit. It is derived from the methyl hydrogen of. From these integrated values, the ethylene content was calculated by the following formula (3), and the degree of saponification was calculated by the following formula (4).

[Alkali metal content]
The alkali metal content was quantified using a spectroscopic analyzer. Specifically, 0.5 g of dried EVOH pellets was added to a pressure-resistant container made of Teflon (registered trademark) manufactured by Actac, and 5 mL of nitric acid (for precision analysis by Wako Pure Chemical Industries, Ltd.) was added. After leaving for 30 minutes, cover the container with a cap lip with a rupture disc, and use a microwave high-speed decomposition system (Actac's "Speedwave MWS-2") at 150 ° C for 10 minutes, then 180 ° C for 10 minutes. Treatment was performed to decompose the dried EVOH pellets. When the decomposition of the dried EVOH pellets was not completed in the above treatment, the treatment conditions were appropriately adjusted. The obtained decomposition product was diluted with 10 mL of ion-exchanged water, the whole solution was transferred to a 50 mL volumetric flask, and the volume was adjusted with ion-exchanged water to obtain a decomposition solution. The alkali metal content was measured by quantitatively analyzing the above-mentioned decomposition solution at a wavelength of 589.592 nm of Na using an ICP emission spectroscopic analyzer (“Optima 4300 DV” manufactured by Perkin Elmer Japan Co., Ltd.).

[Melting viscosity (melt flow rate)]
The melt viscosity (melt flow rate) was measured at a temperature of 190 ° C. and a load of 2,160 g in accordance with JIS-K7210: 1999.

[Measurement of molecular weight of EVOH]
(Preparation of measurement sample)
The measurement sample was prepared by heating EVOH at 220 ° C. for 50 hours in a nitrogen atmosphere.

(GPC measurement)
GPC measurement was performed using "GPCmax" manufactured by VISCOTECH. The molecular weight was calculated based on the signal intensity detected by the differential refractive index detector and the ultraviolet-visible absorbance detector. As the differential refractive index detector and the ultraviolet-visible absorbance detector, "TDA305" and "UV Detector 2600" manufactured by VISCOTECH were used. As the detection cell of this absorbance detector, a cell having an optical path length of 10 mm was used. As the GPC column, "GPC HFIP-806M" manufactured by Showa Denko KK was used. Further, as the analysis software, "OmniSEC (Version 4.7.0.406)" attached to the apparatus was used.

(Measurement condition)
A measurement sample was taken and dissolved in hexafluoroisopropanol (hereinafter, also referred to as “HFIP”) containing 20 mmol / L of sodium trifluoroacetate to prepare a 0.100 wt / vol% solution. For the measurement, a solution filtered through a 0.45 μm polytetrafluoroethylene filter was used. The measurement sample was dissolved by allowing it to stand overnight at room temperature.

As the mobile phase, HFIP containing 20 mmol / L sodium trifluoroacetate was used. The flow rate of the mobile phase was 1.0 mL / min. The sample injection amount was 100 μL, and the measurement was performed at a GPC column temperature of 40 ° C.

(Creation of calibration curve)
As a standard, polymethyl methacrylate (hereinafter abbreviated as "PMMA") manufactured by Agilent Technologies (hereinafter abbreviated as "PMMA") (peak top molecular weight: 1,944,000, 790,000,467,400, 271,400, 144,000, 79, 250, 35, 300, 13, 300, 7,100, 1,960, 1,020 or 690) to measure and convert the elution volume into PMMA molecular weight for each of the differential index detector and absorbance detector. The calibration curve of was created. The above analysis software was used to create each calibration curve. In this measurement, in the measurement of PMMA, a column capable of separating peaks between standard samples having both molecular weights of 1,944,000 and 271,400 was used.

The peak intensity obtained from the differential refractive index detector is represented by "mV", and as a standard sample, American Polymer Standard Corp. When a PMMA sample (PMMA85K: weight average molecular weight 85,450, number average molecular weight 74,300, intrinsic viscosity 0.309) was used as a concentration of 1.000 mg / mL, the peak intensity was 358.31 mV.

The peak intensity obtained from the ultraviolet-visible absorbance detector was represented by the absorbance (absorbance unit), and the absorbance of the ultraviolet-visible absorbance detector was converted to 1 absorption unit = 1,000 mV in the analysis software.

(Quantitative amount of inorganic particles (B))
The content of each inorganic particle (B) was calculated as an oxide-equivalent value by quantifying the metal element by the same method as the above-mentioned method for measuring the alkali metal content. That is, it was calculated as silicon oxide, aluminum oxide, magnesium oxide, zirconium oxide, cerium oxide, tungsten oxide, and / or molybdenum oxide. When a plurality of metals were included, the amount was calculated as a plurality of metal oxide amounts. The amount of the phosphoric acid compound was calculated as a phosphoric acid root conversion value by quantifying the phosphorus element. The content of the boron compound was calculated as a boron element conversion value.

The wavelengths used for the measurement of each metal element are shown below.
Na: 589.592 nm
K: 766.490 nm
Mg: 285.213 nm
Ca: 317.933 nm
P: 214.914 nm
B: 249.667 nm
Si: 251.611 nm
Al: 396.153 nm
Zr: 343.823 nm
Ce: 413.764 nm
W: 207.912 nm
Mo: 202.031 nm

[Preparation of inorganic particles (B)]
As inorganic particles (B) containing silicon atoms, Fuji Silysia Chemical Ltd.'s "Syricia 380" (average particle size 9.0 μm) or "Sylicia 310P" (average particle size 2.7 μm) is crushed and sorted by sieving. , Adjusted to the desired size.

(Measurement of average particle size of inorganic particles (B))
The average particle size of the inorganic particles (B) was measured using a "laser diffraction type particle size distribution measuring device (SALD-2200)" manufactured by Shimadzu Corporation. For the evaluation sample, 50 cc of pure water and 5 g of inorganic particles (B) to be measured were added to a glass beaker, stirred with a spatula, and then dispersed with an ultrasonic cleaner for 10 minutes. Next, a liquid containing the dispersed inorganic particles (B) was added to the sampler part of the apparatus, and the measurement was performed when the absorbance became stable. The distribution (particle size and relative particle amount) was calculated. The average particle size was obtained by dividing the integrated value of the measured particle size multiplied by the relative particle amount by the total relative particle amount. The average particle diameter is the average diameter of the particles.

<Preparation of resin composition>
Inorganic particles (B) were added as shown in Table 1 to obtain dried pellets of the EVOH resin compositions of Examples 1 to 4 and Comparative Example 1.

<Evaluation of resin composition>
A film and a multilayer structure were produced by a method described later, and the EVOH resin compositions of Examples 1 to 4 and Comparative Example 1 were evaluated using the film and the multilayer structure.

[Manufacturing of film]
Using the obtained dried EVOH pellets, the film is melted at 240 ° C., extruded from a die onto a casting roll, and at the same time, air is blown at a wind speed of 30 m / sec using an air knife to create an EVOH unstretched film having an average thickness of 170 μm. Got This EVOH unstretched film is brought into contact with warm water at 80 ° C. for 10 seconds, stretched 3.2 times in the vertical direction and 3.0 times in the horizontal direction in an atmosphere of 90 ° C. using a tenter type simultaneous biaxial stretching machine, and further. The following biaxially stretched film was obtained by performing heat treatment for 5 seconds in a tenter set at 170 ° C. and cutting the end portion of the film.
Average film thickness: 12 μm
Film average width: 50 cm
Average film length: 4,000m
Number: 100

(Measurement of color at the edge of the film)
The obtained biaxially stretched film was wound around a paper tube, and the color of the edge of the film was visually determined as follows.
(Criteria)
A: No coloring B: Light yellow C: Colored

(Measurement of Arithmetic Mean Height (Ra) of Film Surface and Average Length (RSm) of Contour Curve Elements)
For the surface of the obtained biaxially stretched film, the arithmetic average roughness (Ra) and the average of the contour curve elements were used in accordance with JIS-B0610: 2001 using Keyence Co., Ltd. "Shape Measurement Laser Microscope VK-X200". The length (RSm) was measured. The measurement was performed at n = 100, and the average value was taken as each measured value. Each of Ra and RSm was judged as follows.

(Criteria)
Arithmetic Mean Roughness (Ra)
A: 0.20 μm or more and 0.40 μm or less B: 0.15 μm or more and less than 0.20 μm or 0.40 μm or more and 0.60 μm or less C: 0.10 μm or more and less than 0.15 μm or 0.60 μm or more and 0.80 μm or less

Average length of contour curve elements (RSm)
A: 200 μm or more and 400 μm or less B: 150 μm or more and less than 200 μm or more than 400 μm and 600 μm or less C: 100 μm or more and less than 150 μm or more than 600 μm and 800 μm or less

[Evaluation of film breakability]
The biaxially stretched film obtained above was subjected to a slitter, and the number of breaks when the film roll was wound with a tension of 100 N / m was evaluated and determined as follows.

(Criteria)
A: 0 to 1 time / 100 pieces B: 2 to 4 times / 100 pieces C: 5 to 7 times / 100 pieces

[Manufacturing of multilayer structure]
Using the 100 biaxially stretched films obtained above, aluminum was vapor-deposited on one side of the film at a film running speed of 200 m / min using the batch-type vapor deposition equipment EWA-105 manufactured by Nippon Vacuum Technology Co., Ltd. to form a multilayer structure. A body (deposited film) was obtained.

(Measurement of thickness of metal vapor deposition layer)
The obtained multilayer structure was cut with a microtome to expose the cross section. This cross section was observed using a scanning electron microscope (SEM), and the thickness of the metal vapor deposition layer was measured. SEM observation was performed using "ZEISS ULTRA 55" manufactured by SII Nanotechnology Co., Ltd. and using a backscattered electron detector. The evaluation of the ability to suppress vapor deposition defects of the obtained multilayer structure was carried out as follows.

(Measurement of number of thin-film deposition defects (1))
The first roll of the obtained multilayer structure is put on a slitter and unwound while shining a 100 W fluorescent lamp from the bottom of the film, and the number of thin-film deposition defects is counted at n = 10 over a width of 0.5 m and a length of 2 m. The average value was defined as the number of vapor deposition defects per 1 m ^2, and the determination was made as follows.
A: 0 to 20 pieces / m ²
B: 21-40 pieces / m ²
C: 41-60 pieces / m ²

(Measurement of number of thin-film deposition defects (2) (number of thin-film deposition defects over time))
The 100th roll of the obtained multilayer structure was put on a slitter and unwound while shining a 100 W fluorescent lamp from the bottom of the film, and the number of thin-film deposition defects was counted at n = 10 over a width of 0.5 m and a length of 2 m. The average value was defined as the number of vapor deposition defects per 1 m ^2, and the determination was made as follows.
A: 0 to 20 pieces / m ²
B: 21-40 pieces / m ²
C: 41-60 pieces / m ²

(Evaluation of the degree of increase in the number of vapor deposition defects over time)
As an indicator of the long-running property of melt molding of the EVOH resin composition, the degree of increase in the number of vapor deposition defects over time was evaluated and determined as follows.

(Criteria)
A: There was no rank difference in the vapor deposition defects between the first and 100th multilayer structures B: There was one rank difference in the vapor deposition defects between the first and 100th multilayer structures C: Multilayer structure 1 There were two rank differences between the first and 100th vapor deposition defects.

The following measurements were carried out as an evaluation of the adhesion strength between the vapor-deposited layer and the other resin layer in the multilayer structure and film formed from the EVOH resin composition.

(Measurement of adhesion strength between the vapor deposition layer and the EVOH film layer)
An adhesive for dry lamination (Mitsui Chemicals, Inc. "Takelac A-385 / A-50 (mixed at a mass ratio of 6/1) and solid content concentration" was mixed on the surface of the obtained multilayer structure on the metal vapor deposition layer side. 23% by mass ethyl acetate solution) ”was coated with a bar coater, dried with hot air at 50 ° C. for 5 minutes, and then used on a nip roll heated to 80 ° C. for PET film (“E5000” from Toyobo Co., Ltd. The film was laminated with an average thickness of 12 μm). At this time, half of the film was prepared by sandwiching an aluminum foil between them so that the film was not bonded to each other. Then, the film was cured at 40 ° C. for 72 hours to obtain a laminated film. The obtained laminated film was cut into strips of 100 mm × 15 mm centering on the boundary of aluminum vapor deposition, and a T-type peeling test was performed 5 times with a tensile tester at a tensile speed of 10 mm / min. The average value of was taken as the adhesion strength. The adhesion strength was determined as follows.

(Criteria)
A: 500g / 15mm or more B: 450 or more and less than 500g / 15mm C: 400 or more and less than 450g / 15mm

[Manufacturing of film by biaxial stretching]
The resin composition of Example 4 was formed into a film, a film was produced according to a method using a simultaneous biaxial stretching machine, and each physical property was evaluated. As a result, the film surface was measured in accordance with JIS-B0601: 2001. The arithmetic mean roughness (Ra) was 0.28 μm, and the average length (RSm) of the contour curve elements was 298 μm, both of which were judged as A. Further, no yellow coloring was observed on the end face of the roll after being wound as a roll, which was judged as A. Further, the number of breaks during film processing was one, which was judged as A. The average thickness of the aluminum-deposited layer in the manufactured multilayer structure (multilayer structure having an aluminum-deposited layer) was 50 nm. The vapor deposition defect of the first multilayer structure was 9 pieces / m ² , and the vapor deposition defect of the 100th multilayer structure was 12 pieces / m ² , both of which were judged as A. From this, the increase in vapor deposition defects over time was judged as A. The adhesion strength between the aluminum vapor deposition layer and the EVOH film layer of the multilayer structure was 530 g / 15 mm, which was judged as A.

[Manufacturing of film by casting method]
The obtained EVOH resin composition was melted at 240 ° C., extruded from a die onto a casting roll, the edge of the film was cut, and then wound to obtain a film roll. A film roll having excellent appearance characteristics could be obtained.

[Manufacturing of packaging material (pouch)]
The obtained multilayer structure (multilayer structure having an aluminum vapor deposition layer) EVOH film is an intermediate layer, and a PET film (“E5000” of Toyo Boseki Co., Ltd.) is an outer layer (multilayer structure (multilayer structure having an aluminum vapor deposition layer)). (Aluminum vapor-deposited layer side), unstretched polypropylene film (hereinafter abbreviated as CPP; "RXC-18" of Tohcello Corporation, average thickness 60 μm) of the inner layer (multilayer structure (multilayer structure having an aluminum vapor deposition layer)) As the EVOH layer side), a dry laminating adhesive (Mixed by Mitsui Chemicals Co., Ltd. "Takelac A-385 / A-50 (6/1 mass ratio, solid content concentration 23 mass)" on one side of PET and one side of CPP. % Ethyl acetate solution) ”was coated with a bar coater, dried with hot air at 50 ° C. for 5 minutes, and then the PET film and CPP film were sandwiched between the adhesive surfaces of the multilayer structure EVOH film. The film was bonded and aged at 40 ° C. for 5 days to obtain a multilayer structure having a layer structure of PET / adhesive layer / EVOH layer / adhesive layer / CPP. Next, the obtained multilayer structure was heated. It was sealed, molded into a pouch, and filled with 100 g of water.

Table 2 shows the evaluation results of the film and the multilayer structure produced by using each EVOH resin composition.

As is clear from the results in Table 2, the film produced by using the EVOH resin composition of the example is excellent in appearance characteristics and film breakage resistance. Further, among the multilayer structures, the multilayer structure obtained by depositing metal on the film has few vapor deposition defects and is excellent in the adhesion strength between the metal vapor deposition layer and the EVOH film layer. On the other hand, those in which EVOH (A) is outside the specified range of the formula (1) are inferior in these characteristics.

The resin composition of the present invention is excellent in appearance characteristics after melt molding such as the color of the film end (roll end), film breakage resistance, vapor deposition defect suppressing property, and adhesion strength of the vapor deposition layer. The film of the present invention is excellent in appearance characteristics such as color of the film end (roll end) and film breakage resistance. The multilayer structure of the present invention has few vapor deposition defects and is excellent in adhesion strength between the metal vapor deposition layer and other resin layers. The packaging material of the present invention is excellent in appearance characteristics and film breakability. Therefore, these can be suitably used as various packaging materials.

Claims (12)

A resin composition containing an ethylene-vinyl alcohol copolymer and inorganic particles obtained by saponifying a copolymer of ethylene and vinyl ester.
Using a gel permeation chromatograph equipped with a differential refractometer detector and an ultraviolet-visible absorbance detector, the molecular weight measured after heat treatment at 220 ° C. for 50 hours under the nitrogen atmosphere of the ethylene-vinyl alcohol copolymer is the following formula (1). ) meets the condition represented by,
A resin composition characterized in that the content of the inorganic particles is 50 ppm or more and 1,000 ppm or less .
(Ma-Mb) / Ma < 0.10 ... (1)
Ma: Molecular weight converted to polymethylmethacrylate at the maximum value of the peak measured by the differential refractometer Mb: Converted to methylpolymethacrylate at the maximum value of the absorption peak at a wavelength of 220 nm measured by the ultraviolet-visible absorbance detector. Molecular weight Using a gel permeation chromatograph equipped with a differential refractometer detector and an ultraviolet-visible absorbance detector, the molecular weight measured after heat treatment at 220 ° C. for 50 hours under the nitrogen atmosphere of the ethylene-vinyl alcohol copolymer is the following formula (2). The resin composition according to claim 1, further satisfying the condition represented by).
(Ma-Mc) / Ma <0.45 ... (2)
Mc: Molecular weight in terms of polymethyl methacrylate at the maximum value of the absorption peak at a wavelength of 280 nm measured by an ultraviolet-visible absorbance detector The resin composition according to claim 1 or 2 , wherein the average particle size of the inorganic particles is 0.5 μm or more and 10 μm or less. The resin according to any one of claims 1 to 3 , wherein the metal element constituting the inorganic particles is at least one selected from the group consisting of silicon, aluminum, magnesium, zirconium, cerium, tungsten and molybdenum. Composition. The resin composition according to claim 4 , wherein the inorganic substance constituting the inorganic particles is an oxide of the metal element. A film formed from the resin composition according to any one of claims 1 to 5 . The film according to claim 6 , wherein the arithmetic mean roughness (Ra) of at least one surface measured in accordance with JIS-B0601: 2001 is 0.05 μm or more and 1 μm or less. The film according to claim 6 or 7 , wherein the average length (RSm) of the contour curve element of at least one surface measured according to JIS-B0601: 2001 is 50 μm or more and 1,000 μm or less. A multi-layer structure with multiple layers
A multilayer structure in which at least one of the plurality of layers is the film according to claim 6 , claim 7, or claim 8 . At least one of the plurality of layers is a metal vapor deposition layer.
The multilayer structure according to claim 9 , wherein the total average thickness of the metal vapor deposition layers is 30 nm or more and 150 nm or less. The multilayer structure according to claim 10 , wherein the metal vapor deposition layer is the outermost layer of the plurality of layers. A packaging material comprising the multilayer structure according to claim 9 , claim 10 or claim 11 .

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