JP7089351B2 - A resin composition, and a molded body and a multilayer structure using the resin composition. - Google Patents

Description

The present invention relates to a resin composition containing an ethylene-vinyl alcohol copolymer, and a molded product and a multilayer structure using the same.

Ethylene-vinyl alcohol copolymer (hereinafter, may be abbreviated as "EVOH") has high gas shielding properties such as oxygen, transparency, fragrance retention, oil resistance, non-chargeability, mechanical strength, etc. It is a molecular material. Therefore, EVOH is widely used as a material for molded products such as containers. The molded product using EVOH is usually produced by a melt molding method. Therefore, EVOH is required to have an excellent appearance after melt molding.

However, EVOH is a resin that easily absorbs moisture because it has a hydrophilic group, and it is known that voids are likely to be generated due to moisture absorption before molding. For example, Patent Document 1 describes that the water content of the resin composition containing EVOH is preferably 0.5% or less in order to prevent the generation of voids due to foaming or the like during molding. EVOH, which has a low ethylene unit content, is particularly easy to absorb moisture, and even moisture absorption during molding can be a problem. Further, in recent years, in order to improve productivity, there is a demand for a resin composition having excellent melt moldability at high temperature and high speed. However, under such conditions, even when the water content of the resin composition is controlled to be relatively low, defects such as voids are likely to occur, and the moldability may be insufficient.

By the way, as an analysis method for observing the vibration mode of a molecular group due to an intramolecular interaction, a spectroscopic analysis method in the terahertz (hereinafter, may be abbreviated as “THz”) region is known. The terahertz region is a region of electromagnetic waves, which is also called the far-infrared region, and the vibration spectrum peculiar to the substance is observed as in the infrared region. In the infrared spectrum, vibrational modes due to functional groups in the molecule are observed. On the other hand, since the frequency and energy of terahertz light are lower than those in the infrared region, vibration due to weak interaction between relatively large ones, that is, vibration mode of molecular population due to molecular interaction is observed. The vibrational modes observed in the terahertz spectrum of organic solids reflect molecular populations, crystal structures, and higher-order structures of macromolecules. Therefore, terahertz spectroscopy and terahertz imaging can visualize changes in the higher-order structure of macromolecules and the spatial distribution of macromolecules.

In addition, a spectrum obtained by a spectrophotometer when analyzing the characteristics of a sample when an external perturbation is applied (for example, when the external temperature is changed) in the wavelength region from near-infrared light to infrared light. It is known that the above data can be analyzed using two-dimensional correlation spectroscopy (2D-COS). For example, Non-Patent Document 2 describes the result of analyzing the characteristics of the spectral change with heating of the linear low-density polyethylene when the external perturbation is set to the temperature in the wavelength region of infrared light. Further, Non-Patent Document 3 describes the result of analyzing the characteristics of the spectral change with the crystallization time of poly (3-hydroxybutyrate) when the external perturbation is set to the isothermal crystallization time in the terahertz region. There is.

WO2011 / 118648

I. Noda et al., “Generalized Two-Dimensional Correlation Spectroscopy”, Applied Spectroscopy, Vol. 54, Number 7, 2000, p.236A-248A H. Hoshina et al., “Isothermal crystallization of poly (3-hydroxybutyrate) studied by terahertz two-dimensional correlation spectroscopy”, Applied Physics Letters, 2012, 100, 011907

The present invention has been made to solve the above problems, and provides a resin composition that is less likely to cause appearance defects such as voids even when melt molding is performed at a high temperature, and is suitably used for a high temperature and high speed process. The purpose is to do.

As a result of diligent studies, the present inventors have found that a resin composition exhibiting a specific behavior in terahertz spectroscopy is less likely to generate voids even when melt-molded at a high temperature.

The above-mentioned problem is a resin composition containing EVOH (A) as a main component, wherein the ethylene unit content of EVOH (A) is 20 to 55 mol%, the saponification degree is 90 mol% or more, and the following From the absorption curve obtained by irradiating a single-layer film having a thickness of 60 μm made of the resin composition, which was adjusted at each relative humidity, with terahertz light in the range of 1 to 8 THz, the humidity was adjusted at 0% relative humidity. In the time-dependent correlation spectrum obtained by using the two-dimensional correlation spectroscopy, the frequency y ( When the case where the value of the difference spectrum corresponding to the frequency x (X-axis) increases earlier than the value of the difference spectrum corresponding to the Y-axis) is positive, the value of the extraordinary correlation spectrum (Z-axis) becomes It is solved by providing a resin composition in which the value of x having the maximum positive value is 5.2 THz or more and less than 6.0 THz.
Relative humidity (%): 11, 22, 33, 44, 55, 66, 76, 86, 90, 100

At this time, it is preferable that EVOH (A) contains 0.0005 to 1 mol% of an alkoxyl group. It is also preferable that the resin composition contains 0.05 to 90 ppm of unsaturated aliphatic aldehyde (B). It is also preferred that the unsaturated aliphatic aldehyde (B) is at least one selected from the group consisting of crotonaldehyde, 2,4-hexadienal and 2,4,6-octatrienal. It is also preferable that the resin composition contains 10 to 500 ppm of alkali metal ion (C).

A molded product containing the resin composition is a preferred embodiment of the present invention. A multilayer structure having a layer made of the resin composition is also a preferred embodiment of the present invention.

By using the resin composition of the present invention, a molded product having few defects such as voids can be obtained even when melt molding is performed at a high temperature. Therefore, the resin composition is suitably used for high temperature and high speed processes. Further, by using the resin composition, it is possible to provide a molded body or a multilayer structure having an excellent appearance at a low cost.

In Example 1, it is a difference spectrum obtained by terahel spectroscopic measurement of a monolayer film at each relative humidity. In Example 1, it is an extraordinary correlation spectrum obtained from a difference spectrum.

[Resin composition]
The resin composition of the present invention contains EVOH (A) as a main component, and has an ethylene unit content of 20 to 55 mol% and a saponification degree of 90 mol% or more. From the absorption curve obtained by irradiating a single-layer film having a thickness of 60 μm made of the resin composition, which has been adjusted at each of the following relative humidities, with terahertz light in the range of 1 to 8 THz, the relative humidity is adjusted at 0%. In the intertemporal correlation spectrum obtained by using the two-dimensional correlation spectroscopy with respect to the difference spectrum obtained by subtracting the absorption curve obtained by irradiating the moistened single-layer film with terahertz light in the range of 1 to 8 THz. When the case where the value of the difference spectrum corresponding to the frequency x (X-axis) increases earlier than the value of the difference spectrum corresponding to the frequency y (Y-axis) is positive, the value of the extraordinary correlation spectrum (Z). The value of x having the maximum positive value on the axis) is 5.2 THz or more and less than 6.0 THz.
Relative humidity (%): 11, 22, 33, 44, 55, 66, 76, 86, 90, 100

(Terahertz spectroscopy)
The terahertz region is a region of electromagnetic waves, which is also called the far-infrared region, and the vibration spectrum peculiar to the substance is observed as in the infrared region. In the infrared spectrum, vibrational modes due to functional groups in the molecule are observed. On the other hand, since the frequency and energy of terahertz light are lower than those in the infrared region, vibration due to weak interaction between relatively large ones, that is, vibration mode of molecular population due to molecular interaction is observed. The vibrational modes observed in the terahertz spectrum of organic solids reflect molecular populations, crystal structures, and higher-order structures of macromolecules. Therefore, terahertz spectroscopy and terahertz imaging can visualize changes in the higher-order structure of macromolecules and the spatial distribution of macromolecules.

In the present invention, the resin composition is used as a single-layer film having a thickness of 60 μm, and then the relative humidity is 0, 11, 22, 33, 44, 55, 66, 76, 86, 90 or 100%, and the temperature is 25 ° C. After monthly humidity control, terahertz spectroscopic measurement is performed by irradiating terahertz light in the range of 1 to 8 THz. Then, from the absorption curve obtained by measuring the single-layer film adjusted at each relative humidity (11, 22, 33, 44, 55, 66, 76, 86, 90 or 100%), the relative humidity is 0%. The difference spectrum is obtained by subtracting the absorption curve obtained by measuring the humidity-controlled monolayer film in. FIG. 1 is a difference spectrum obtained by terahel spectroscopic measurement of a single-layer film at each relative humidity in Example 1 described later.

The data obtained by terahertz spectroscopy is analyzed by the two-dimensional correlation spectroscopy (2D-COS) described in Applied Spectroscopy, Vol. 54, Issue 7, p.236A-248A. In the present invention, 2D-COS is used to obtain an Asynchronous 2D correlation spectrum from the difference spectrum. FIG. 2 is an extra-temporal correlation spectrum obtained from the difference spectrum (FIG. 1) in Example 1 described later. The time-dependent correlation spectrum will be described with reference to FIG. In the present invention, the transient correlation spectral intensity is plotted as a function of frequency, which is a spectral variable. A 2D spectral plane is defined by the orthogonal axes of the X-axis and the Y-axis representing the frequency which is a spectral variable, and the extraordinary correlation spectrum intensity is plotted on the X-axis and the Z-axis perpendicular to the Y-axis.

The spectrum obtained by 2D-COS can be represented by a metachronous correlation spectrum. In the intertemporal correlation spectrum, the intensity represents a sequential or continuous change in the data (difference spectrum) obtained by terahertz spectroscopy with respect to external perturbations (relative humidity). By using the extraordinary correlation spectrum, it is possible to express the correlation of the change between the two peaks in the data (difference spectrum) obtained by the terahertz spectroscopic measurement. That is, the correlation between the change in the value of the difference spectrum corresponding to the frequency x (X-axis) and the change in the value of the difference spectrum corresponding to the frequency y (Y-axis) when the relative humidity is changed is the time-dependent correlation spectrum. Indicated by the value (Z-axis). In the present invention, when the value of the difference spectrum corresponding to the frequency x (X-axis) increases earlier than the value of the difference spectrum corresponding to the frequency y (Y-axis) due to an increase in relative humidity, the time-dependent correlation occurs. Let the value of the spectrum be positive.

In the resin composition of the present invention, the value of the frequency x (X-axis) at which the value (Z-axis) of the time-dependent correlation spectrum thus obtained has the maximum positive value must be 5.2 THz or more and less than 6.0 THz. be. The present inventors have found that a positive maximum value exists in the low frequency region near 4-5 THz (X-axis) in a general EVOH time-correlated spectrum obtained in the same manner as described above. .. It is speculated that the peak in this low frequency region is derived from the change in the intramolecular vibration expansion / contraction mode between EVOH and water molecules. On the other hand, the resin composition of the present invention has a positive maximum value of the extraordinary correlation spectral intensity in the region of 5.2 THz or more and less than 6.0 THz (X-axis). This means that the interaction between EVOH (A) and water molecules is strong. As described above, in the resin composition of the present invention, since the interaction between EVOH (A) and water molecules is strong, it can be considered that water is difficult to be released even when melt-molded at a high temperature. As a result, it is presumed that the generation of voids is suppressed and a molded body having an excellent appearance can be obtained.

As a means for obtaining a resin composition in which the value of the frequency x (X-axis) at which the value of the extraordinary correlation spectrum (Z-axis) has the maximum positive value is 5.2 THz or more and less than 6.0 THz.
(1) Use a polymerization initiator containing an alkoxyl group as a polymerization initiator used when producing an ethylene-vinyl ester copolymer (2) Set the polymerization temperature when producing an ethylene-vinyl ester copolymer. Set relatively high (3) Adjust the content of unsaturated aliphatic aldehyde (B) in the resin composition to an appropriate range (4) Increase the saponification degree of EVOH (A) (5) Adjusting the content of alkali metal salt in the resin composition to an appropriate range (6) Adjusting the content of carboxylic acid and carboxylic acid ion in the resin composition to an appropriate range (7) Resin composition It can be mentioned that the content of the lubricant in the medium is adjusted to an appropriate range. In producing the resin composition of the present invention, one of these means may be adopted, or a plurality of these means may be adopted.

When a polymerization initiator containing an alkoxyl group is used in the manufacturing process of the resin composition, the value of the frequency x (X-axis) at which the value of the time-dependent correlation spectrum (Z-axis) has the maximum positive value tends to increase. There is. Although the reason is not clear, the presence of an alkoxyl group facilitates the formation of hydrogen bonds, and the presence of a bulky structure at the end of EVOH (A) weakens the interaction between the ends of EVOH (A). Therefore, it is presumed that EVOH (A) and water are more likely to interact with each other. Further, by setting the polymerization temperature relatively high, the value of the frequency x (X-axis) at which the value of the time-dependent correlation spectrum (Z-axis) has a positive maximum value tends to increase. Although the reason is not clear, it is presumed that the increase in EVOH (A) having a hydrophilic heterogeneous structure at the terminal facilitates the formation of hydrogen bonds. Further, by containing the unsaturated aliphatic aldehyde (B) in the resin composition, the value of the frequency x (X-axis) at which the value of the time-dependent correlation spectrum (Z-axis) has a positive maximum value becomes large. Tend. Although the reason is not clear, it is presumed that the plasticizing effect of the unsaturated aliphatic aldehyde (B) makes it easier for water molecules to approach EVOH (A) and strengthens the interaction.

(EVOH (A))
EVOH (A) is a copolymer having an ethylene unit and a vinyl alcohol unit.

The ethylene unit content of EVOH (A) should be 20-55 mol%. This makes it possible to obtain a resin composition having both excellent melt moldability and gas barrier properties. When the ethylene unit content is less than 20 mol%, the long-run property when the resin composition is melt-molded is lowered, and the water resistance, heat resistance and water barrier property of the obtained molded product under high humidity are also improved. descend. The ethylene unit content is preferably 25 mol% or more. On the other hand, when the ethylene content exceeds 55 mol%, the gas barrier property of the obtained molded product is lowered. The ethylene unit content is preferably 50 mol% or less. Further, from the following points, the ethylene unit content is more preferably 45 mol% or less, and further preferably 35 mol% or less. Generally, the smaller the ethylene unit content, the easier it is for EVOH to absorb moisture, so that voids are more likely to occur in the obtained molded product. On the other hand, in the resin composition of the present invention, voids are unlikely to occur even when the ethylene unit content of EVOH (A) contained is low. Therefore, when the ethylene unit content of EVOH (A) is low, the merit of using the resin composition of the present invention is great.

The saponification degree of EVOH (A) needs to be 90 mol% or more. Thereby, a resin composition having excellent gas barrier properties and appearance can be obtained. The degree of saponification is preferably 95 mol% or more, more preferably 99 mol% or more, still more preferably 99.9 mol% or more. The ethylene unit content and saponification degree of EVOH (A) can be determined by ¹ H-NMR measurement using DMSO-d ₆ as a solvent.

EVOH (A) is usually obtained by saponifying an ethylene-vinyl ester copolymer obtained by copolymerizing ethylene and vinyl ester. As a polymerization method of ethylene and vinyl ester, known methods such as solution polymerization, suspension polymerization, emulsion polymerization and bulk polymerization are adopted. Further, the polymerization method may be either a continuous method or a batch method. For example, in the case of solution polymerization, the following conditions can be adopted.

Alcohol is preferable as the solvent used for solution polymerization. For example, methyl alcohol, ethyl alcohol, propyl alcohol, n-butyl alcohol, t-butyl alcohol and the like can be mentioned, and methyl alcohol is particularly preferable. Further, an organic solvent other than alcohol (dimethyl sulfoxide or the like) capable of dissolving the ethylene, vinyl ester and ethylene-vinyl ester copolymer can also be used for solution polymerization.

Various radical initiators are used as the polymerization initiator. Of these, a radical initiator containing an alkoxyl group is preferable. By using a radical initiator containing an alkoxyl group, an alkoxyl group is introduced into EVOH (A), so that the value (Z-axis) of the metachronous correlation spectrum has a positive maximum value at the frequency x (X-axis). It becomes easy to adjust the value within the above range. As radical initiators containing an alkoxyl group, 2,2'-azobis- (4-methoxy-2,4-dimethylvaleronitrile) and 2,2'-azobis- (4-ethoxy-2,4-diethylvaleronitrile) ) And the like, an azonitrile-based initiator containing an alkoxyl group is more preferable.

The polymerization time is usually 2 hours or more and 15 hours or less, preferably 3 hours or more and 11 hours or less. The polymerization rate is usually 10 mol% or more and 90 mol% or less, preferably 20 mol% or more and 80 mol% or less, based on the vinyl ester to be charged. The resin content in the solution after polymerization is usually 5% by mass or more and 85% by mass or less, preferably 20% by mass or more and 70% by mass or less.

The polymerization temperature is usually 20 ° C. or higher, preferably 40 ° C. or higher. The polymerization temperature is preferably 50 ° C. or higher, more preferably 50 ° C. or higher, from the viewpoint that the value of the frequency x (X-axis) at which the value of the extraordinary correlation spectrum (Z-axis) has the maximum positive value can be easily adjusted within the above range. It is 65 ° C. or higher, more preferably 75 ° C. or higher. On the other hand, the polymerization temperature is usually 90 ° C. or lower, preferably 85 ° C. or lower.

Examples of the vinyl ester used for the polymerization include aliphatic vinyl esters such as vinyl acetate, vinyl formate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl versatic acid, and vinyl caproate. Vinyl acetate is preferred.

EVOH (A) may contain units derived from other ethylenically unsaturated monomers that can be copolymerized with ethylene and vinyl esters, as long as the effects of the present invention are not impaired. Examples of such ethylenically unsaturated monomers include α-olefins such as propylene, n-butene, isobutylene, and 1-hexene;
Unsaturated monomers with 1,2-diester groups such as 3,4-diacetoxy-1-butene;
2-Methylene-1,3-propanediol diacetate (1,3-diacetoxy-2-methylenepropane), 2-methylene-1,3-propanediol dipropionate, 2-methylene-1,3-propanediol dibuty Unsaturated monomer having 1,3-diester group such as rate;
Acrylic acid and its salts;
Unsaturated monomer having an acrylic acid ester group;
Methacrylic acid and its salts;
Unsaturated monomer with methacrylic acid ester group;
Acrylamide, N-methylacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide, diacetoneacrylamide, acrylamide propanesulfonic acid and its salts, acrylamide propyldimethylamine and its salts (eg, quaternary salts);
Methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamide propanesulfonic acid and its salts, methacrylamidepropyldimethylamine and its salts (eg, quaternary salts);
Methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, stearyl vinyl ether, 2,3-diacetoxy-1-vinyloxypropane, etc. Vinyl ethers;
Vinyl cyanide such as acrylonitrile and methacrylonitrile; Vinyl halides such as vinyl chloride and vinyl fluoride;
Halogenated vinylidenes such as vinylidene chloride and vinylidene fluoride;
Allyl compounds such as allyl acetate, 2,3-diacetoxy-1-allyloxypropane, allyl chloride;
Unsaturated dicarboxylic acids such as maleic acid, itaconic acid, fumaric acid and salts thereof or esters thereof;
Vinylsilane compounds such as vinyltrimethoxysilane;
Examples include isopropenyl acetate. The content of the monomer unit other than the ethylene unit and the vinyl alcohol unit in EVOH (A) is preferably 10 mol% or less, more preferably 5 mol% or less, still more preferably 1 mol% or less.

When the predetermined polymerization rate is reached, a polymerization inhibitor is added as necessary to evaporate and remove the unreacted ethylene gas, and then the unreacted vinyl ester is removed. As a method for removing the unreacted vinyl ester from the ethylene-vinyl ester copolymer, for example, the copolymer solution is continuously supplied at a constant rate from the upper part of the column filled with Rasichling, and methanol or the like is continuously supplied from the lower part of the column. A method is adopted in which a mixed vapor of an organic solvent such as methanol and an unreacted vinyl ester is distilled from the top of the column, and an ethylene-vinyl ester copolymer solution is taken out from the bottom of the column.

The saponification of the ethylene-vinyl ester copolymer is carried out by a known method such as acid saponification or alkali saponification. For example, when performing alkali saponification, an alkali catalyst is added to the ethylene-vinyl ester copolymer solution obtained above to saponify the vinyl ester moiety. The saponification method can be either continuous or batch. As the alkali catalyst, sodium hydroxide, potassium hydroxide, alkali metal alcoholate and the like are used.

When saponification is performed, for example, in the case of a batch type, the concentration of the ethylene-vinyl ester copolymer solution is usually 10% by mass or more and 50% by mass or less. The reaction temperature is usually 30 ° C. or higher and 60 ° C. or lower. The amount of the catalyst used is usually 0.02 to 0.6 mol per 1 mol of the vinyl ester monomer unit. The reaction time is usually 1 hour or more and 6 hours or less. In the case of the continuous type, the method of performing the saponification reaction while efficiently removing the carboxylic acid methyl ester and the like generated by the saponification reaction using a conventionally known tower type reactor is the amount of the alkaline catalyst used. Is preferable in that it can be reduced. At this time, the reaction temperature should be 70 to 150 ° C. and the amount of catalyst used should be 0.001 to 0.2 mol per mol of the vinyl ester monomer unit because the reaction can be carried out in a uniform solution. preferable.

Since the EVOH (A) thus obtained contains the residue of the catalyst used in the saponification reaction, by-products salts, and other impurities, the impurities are removed by neutralization and washing as necessary. Is preferable.

The melt flow rate of EVOH (A) (temperature 210 ° C., load 2160 g, hereinafter, the melt flow rate is abbreviated as MFR) is preferably 0.1 to 200 g / 10 minutes. When the MFR of EVOH (A) is in such a range, the moldability and processability of the resin composition and the appearance of the obtained molded product are good. The MFR of EVOH (A) is more preferably 0.5 g / 10 minutes or more, further preferably 1 g / 10 minutes or more. On the other hand, the MFR of EVOH (A) is more preferably 50 g / 10 minutes or less, further preferably 30 g / 10 minutes or less, particularly preferably 15 g / 10 minutes or less, and most preferably 10 g / 10 minutes or less. In the present invention, the meltle flow rate is measured according to JIS K 7210.

The EVOH (A) may consist of a mixture of two or more types of EVOH. In this case, the ethylene unit content, the degree of saponification and the MFR shall be weighted average values by the compounding mass ratio. From the viewpoint of production cost and uniformity of the obtained product, the resin composition of the present invention preferably contains one kind of EVOH. On the other hand, from the viewpoint of achieving both barrier properties and various mechanical properties, the resin composition of the present invention preferably contains two types of EVOH having different ethylene unit contents. At this time, it is preferable that the ethylene unit contents of the two types of EVOH differ by 5 mol% or more, and more preferably by 10 mol% or more. Further, the mass ratio of these EVOH is preferably 1/99 to 99/1, and more preferably 5/95 to 95/5.

The resin composition of the present invention contains EVOH (A) as a main component. Here, the principal component means the component having the highest content on a mass basis. The content of EVOH (A) in the resin composition of the present invention is preferably 55% by mass or more. If the content is less than 55% by mass, the gas barrier property and moldability of the resin composition may be insufficient. The content is more preferably 80% by mass or more, further preferably 90% by mass or more, particularly preferably 95% by mass or more, and most preferably 99% by mass or more.

(Alkoxy group content)
It is preferable that EVOH (A) contains 0.0005 to 1 mol% of an alkoxyl group. As a result, it becomes easy to adjust the value of the frequency x (X-axis) at which the value of the extraordinary correlation spectrum (Z-axis) has a positive maximum value within the above range. The content of the alkoxyl group is more preferably 0.0007 mol% or more, still more preferably 0.001 mol% or more. On the other hand, when the content of the alkoxyl group exceeds 1 mol%, the drawdown resistance, the interlayer adhesiveness and the gas barrier property tend to deteriorate. The content of the alkoxyl group is more preferably 0.5 mol% or less, still more preferably 0.3 mol% or less. In the present invention, the content of the alkoxyl group of EVOH (A) means the ratio of the unit having an alkoxyl group to all the monomer units.

When an alkoxyl group is contained in EVOH (A) by using a polymerization initiator containing an alkoxyl group, the amount of the alkoxyl group used, the polymerization temperature, the type and amount of the polymerization solvent, etc. are appropriately adjusted to obtain the alkoxyl group. The content can be adjusted. When an alkoxyl group is contained in EVOH (A) by copolymerizing a monomer containing an alkoxyl group, the content of the alkoxyl group can be adjusted by appropriately adjusting the monomer ratio.

(Unsaturated aliphatic aldehyde (B))
It is preferable that the resin composition contains unsaturated aliphatic aldehyde (B) at 0.05 ppm or more and 90 ppm or less. If the content of the unsaturated aliphatic aldehyde (B) is less than 0.05 ppm, defects such as voids may easily occur in the high temperature process. The content of the unsaturated aliphatic aldehyde (B) is more preferably 0.1 ppm or more, further preferably 0.2 ppm or more. On the other hand, if the content of the unsaturated aliphatic aldehyde (B) exceeds 90 ppm, the unsaturated aldehyde (B) may be condensed during melt molding, or the condensate of the EVOH (A) and the unsaturated aliphatic aldehyde (B). May react and cause cross-linking. As a result, the resin composition may become thickened or gelled, which may cause gels or lumps, or defects such as streaks. Here, the content of the unsaturated aliphatic aldehyde (B) in the resin composition is expressed as a ratio to the total solid content mass of the resin composition. Specifically, the value obtained by quantifying the unsaturated aliphatic aldehyde (B) contained in the resin composition excluding water is used.

The unsaturated aliphatic aldehyde (B) is an aldehyde having a carbon-carbon double bond or a triple bond. Examples of aldehydes having a carbon-carbon double bond used as unsaturated aliphatic aldehydes (B) include acrylic aldehyde (acrolein), croton aldehyde, methacrylic aldehyde, 2-methyl-2-butenal, 2-butynal, and 2-hexenal. , 2,6-nonadienal, 2,4-hexadienal, 2,4,6-octatrienal, 2-hexenal, 5-methyl-2-hexenal and the like. Examples of the aldehyde having a carbon-carbon triple bond used as the unsaturated aliphatic aldehyde (B) include propiol aldehyde, 2-butyne-1-ar, 2-pentyne-1-ar and the like. Among them, as the unsaturated aliphatic aldehyde (B), an unsaturated aliphatic aldehyde having a linear or branched carbon-carbon double bond is preferable, and crotonaldehyde, 2,4-hexadienal and 2,4 are preferable. It is more preferably at least one selected from the group consisting of 6-octatrienal, and even more preferably crotonaldehyde. Since crotonaldehyde has high solubility in water and has a boiling point of about 100 ° C., it is easy to remove excess or add deficiency as needed in a washing step or a drying step. The unsaturated aliphatic aldehyde (B) preferably has 3 to 10 carbon atoms, more preferably 4 to 8 carbon atoms.

(Alkali metal ion (C))
It is preferable that the resin composition further contains an alkali metal ion (C). When the resin composition contains alkali metal ions, the adhesiveness to other resins is improved. In particular, the interlayer adhesiveness is improved in a multilayer structure having a layer made of the resin composition and a layer made of a thermoplastic resin other than EVOH (A).

Examples of the alkali metal ion (C) include lithium ion, sodium ion, potassium ion and the like, and sodium ion and potassium ion are preferable. In the present invention, it is preferable that the alkali metal ion (C) is contained in the resin composition as an alkali metal salt. Examples of the alkali metal salt include aliphatic carboxylates such as lithium, sodium and potassium, aromatic carboxylates, carbonates, hydrochlorides, nitrates, sulfates, phosphates, metal complexes and the like. Among these, sodium acetate, potassium acetate, sodium carbonate, potassium carbonate, sodium phosphate and potassium phosphate are preferable because they are easily available.

The resin composition of the present invention preferably contains an alkali metal ion (C) at 10 to 500 ppm in terms of metal element. The content of the alkali metal ion (C) is more preferably 30 ppm or more, further preferably 100 ppm or more. Further, the content is more preferably 400 ppm or less, further preferably 300 ppm or less. When the content of the alkali metal ion (C) is 10 ppm or more, the effect of the alkali metal ion (C) described above is exhibited. On the other hand, when the content of the metal ion (C) is 500 ppm or less, coloring of the resin composition can be suppressed.

The resin composition may contain a thermoplastic resin other than EVOH (A) as long as the effects of the present invention are not impaired. Examples of the thermoplastic resin other than EVOH (A) include polyolefins [polyethylene, polypropylene, poly (1-butene), poly (4-methyl-1-pentene), ethylene-propylene copolymer, ethylene and 4 or more carbon atoms. Copolymer with α-olefin, copolymer of olefin and maleic anhydride, ethylene-vinyl ester copolymer, ethylene-acrylic acid ester copolymer, or graft modification of these with unsaturated carboxylic acid or a derivative thereof. Modified polyolefin, etc.], nylon (nylon 6, nylon 66, nylon 6/66 copolymer, etc.), polyvinyl chloride, polyvinylidene chloride, polyester, polystyrene, polyacrylonitrile, polyurethane, polyacetal, modified polyvinyl alcohol resin, etc. Be done. When the resin composition contains a thermoplastic resin other than EVOH (A), the content thereof is preferably less than 50% by mass, more preferably less than 30% by mass, still more preferably less than 10% by mass, and less than 1% by mass. Is particularly preferable, and less than 0.1% by mass is most preferable.

(Other additives)
The resin composition contains additives other than the above-mentioned EVOH (A), unsaturated aliphatic aldehyde (B), alkali metal ion (C) and other thermoplastic resins as long as the effects of the present invention are not impaired. You may be doing it. Examples of such other additives include plasticizers, stabilizers, surfactants, coloring agents, ultraviolet absorbers, slip agents, antistatic agents, desiccants, cross-linking agents, fillers, oxygen absorbers, various fibers and the like. Can be mentioned. The content of the other additives in the resin composition is preferably less than 10% by mass, more preferably less than 1% by mass, still more preferably less than 0.1% by mass.

From the viewpoint of thermal stability and viscosity adjustment, the resin composition is a carboxylic acid as an additive other than EVOH (A), unsaturated aliphatic aldehyde (B), alkali metal ion (C) and other thermoplastic resins. , Phosphorus compound or boron compound may be contained. Specific examples include the following. In addition, these compounds may be contained in EVOH (A) in advance.
Carboxylic acid: oxalic acid, succinic acid, benzoic acid, citric acid, acetic acid, lactic acid, etc. Phosphorus compound: various acids such as phosphoric acid, phosphite, and salts thereof Boron compound: boric acid, borate ester, borate , Boron hydride, etc.

The MFR of the resin composition is preferably in the same range as that of EVOH (A). The effect obtained by setting the MFR of the resin composition in such a range is also the same as in the case of EVOH (A).

(Manufacturing method of resin composition)
The method for producing the resin composition of the present invention is not particularly limited. The resin composition can be obtained by mixing EVOH (A) and other components by a known method. Further, the resin composition can also be obtained by immersing EVOH (A) in an aqueous solution in which other components are dissolved and containing the other components in EVOH (A).

The method for incorporating the unsaturated aliphatic aldehyde (B) into the resin composition is not particularly limited, but for example, the unsaturated aliphatic aldehyde (B) is previously mixed with EVOH (A) to granulate pellets. Method, a method of impregnating the strands precipitated in the step of precipitating the paste after the saponification of the ethylene-vinyl ester copolymer with the unsaturated aliphatic aldehyde (B), the method of impregnating the precipitated strands with the unsaturated aliphatic aldehyde ( A method of impregnating B), a method of adding an unsaturated aliphatic aldehyde (B) to a redissolved chip of a resin composition (dried) containing EVOH (A), EVOH (A) and no A method of melt-kneading a blend of two components of a saturated aliphatic aldehyde (B), a method of adding an unsaturated aliphatic aldehyde (B) to a melt of EVOH (A) in an extruder, an EVOH ( A method in which a master batch is granulated by blending a part of A) with an unsaturated aliphatic aldehyde (B) at a high concentration, and then the master batch and EVOH (A) are dry-blended and then melt-kneaded. Can be mentioned.

Of these, from the viewpoint that the unsaturated aliphatic aldehyde (B) can be uniformly dispersed in the EVOH (A), the unsaturated aliphatic aldehyde (B) is previously mixed with the EVOH (A) to prepare pellets. The granulation method is preferred. Specifically, unsaturated aliphatic aldehyde (B) is added to a solution in which EVOH (A) is dissolved in a good solvent to obtain a mixed solution. Pellets in which unsaturated aliphatic aldehyde (B) is uniformly mixed with EVOH (A) by extruding the mixed solution from a nozzle or the like into a poor solvent to precipitate and / or coagulate and then washing and / or drying. Can be obtained.

[Molded product]
A molded product containing the resin composition thus obtained is a preferred embodiment of the present invention. The molded product may be composed of only the resin composition, or may have a portion composed of the resin composition and a portion composed of a portion other than the resin composition.

Molds containing the resin composition include pellets, films, sheets, containers (bags, cups, tubes, trays, bottles, etc.), fuel containers, pipes, fibers, food and beverage packaging materials, container packing materials, and the like. Medical infusion bag material, tire tube material, shoe cushion material, bag-in-box inner bag material, organic liquid storage tank material, organic liquid transport pipe material, hot water pipe material for heating (hot water pipe material for floor heating) Etc.), Cosmetic packaging materials, dental care packaging materials, pharmaceutical packaging materials, packaging material child parts (caps, bag-in-box cock parts, etc.), pesticide bottles, agricultural films (greenhouse films, soil steaming) (Film), a bag for storing grains, a geomembrane, a wallpaper or a decorative board, a gas tank for hydrogen, oxygen, etc. can be mentioned. As the fuel container, a fuel container mounted on an automobile, a motorcycle, a ship, an aircraft, a generator, an industrial device, an agricultural device, etc., a portable container for refueling the fuel container, and a fuel are stored. For example, a container for fuel. A typical example of the fuel is gasoline, in particular, gasoline blended with methanol, ethanol, MTBE, or the like, that is, oxygen-containing gasoline. Further, other heavy oil, light oil, kerosene and the like can be mentioned.

The molded product is usually produced by melt-molding the resin composition. These molded bodies can be crushed for reuse and then remolded. It is also possible to uniaxially or biaxially stretch a film, sheet, fiber or the like. As a melt molding method, a known method is adopted, and examples thereof include extrusion molding, inflation extrusion, blow molding, melt spinning, and injection molding. The melting temperature at the time of melt molding is preferably 150 to 300 ° C. Above all, 250 ° C. or higher is particularly preferable. The resin composition of the present invention is less likely to cause defects such as voids even in a high temperature process. Therefore, the resin composition is suitably used for high temperature and high speed processes.

As the molded body, a multilayer structure having a layer made of the resin composition and a layer made of a thermoplastic resin other than EVOH (A) is preferable. By melt-molding the resin composition and another thermoplastic resin, a multilayer structure having an excellent appearance can be produced with high productivity.

The thickness structure of the multilayer structure is not particularly limited, but the thickness ratio of the resin composition layer to the total layer thickness is preferably 2 to 20% from the viewpoint of moldability and cost. The layer structure of the multilayer structure is not particularly limited, but if the other thermoplastic resin layer is A, the resin composition layer is B, and the adhesive resin layer is C, A / B, A / B / A, A. Layer configurations such as / C / B, A / C / B / C / A, A / B / A / B / A, A / C / B / C / A / C / B / C / A are exemplified. .. It is not possible to add another layer to these. When a plurality of other thermoplastic resin layers are provided, different ones may be used or the same ones may be used. Further, a layer of a recovered resin made of scrap such as trim generated during molding may be separately provided, or a layer made of a blend of the recovered resin and another thermoplastic resin may be used as another thermoplastic resin layer.

As the adhesive resin, a carboxylic acid-modified polyolefin is preferable. As the carboxylic acid-modified polyolefin, a modified polyolefin containing a carboxyl group obtained by chemically (for example, addition reaction, graft reaction, etc.) a ethylenically unsaturated carboxylic acid, an ester thereof or an anhydride thereof is bonded to the polyolefin is preferable. Can be used for. Examples of the ethylenically unsaturated carboxylic acid used at this time include maleic acid, fumaric acid, and itaconic acid. Examples of the ethylenically unsaturated carboxylic acid anhydride include maleic anhydride and itaconic anhydride. Examples of the ethylenically unsaturated carboxylic acid ester include maleic acid monomethyl ester, maleic acid monoethyl ester, maleic acid diethyl ester, and fumaric acid monomethyl ester. Of these, it is preferable to use maleic anhydride. These adhesive resins may be used alone or in combination of two or more.

Other thermoplastic resins used in the multilayer structure include polyethylene (linear low density polyethylene, low density polyethylene, medium density polyethylene, high density polyethylene), ethylene-vinyl acetate copolymer, and ethylene-propylene co-weight. Combined, polypropylene, propylene-α-olefin copolymer, polyolefin such as polybutene, polypentene; polyester such as polyethylene terephthalate; polyester elastomer; polyamide such as nylon 6, nylon 66; polystyrene; polyvinyl chloride; polyvinylidene chloride; acrylic Resins; vinyl ester-based resins; polyurethane elastomers; polycarbonates; chlorinated polyethylene; chlorinated polypropylene. Among these, polypropylene, polyethylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, polyamide, polystyrene and polyester are preferable.

It is preferable to use a polyolefin layer as another thermoplastic resin layer of the multilayer structure. This is because the provision of the polyolefin layer improves not only the mechanical properties of the multilayer structure but also the moisture resistance. In particular, it is preferable to provide the polyolefin layers on both outer layers of the multilayer structure because the moisture absorption of the resin composition layer is effectively prevented. At this time, the recovered resin can be contained in the polyolefin layer as long as the effect is not impaired.

Examples of the method for manufacturing the multilayer structure include the following methods.
(1) A method of co-extruding the resin composition and another thermoplastic resin (2) A method of melt-extruding another thermoplastic resin onto a molded body made of the resin composition (3) Another thermoplastic resin A method of melt-extruding the resin composition onto a molded body made of the above resin composition (4) A method of co-injecting the resin composition with another thermoplastic resin (5) A molded body made of the resin composition and other thermoplastics A method of laminating a molded body made of resin using an adhesive resin

Among these methods, (1) is preferable. The resin composition of the present invention is unlikely to have defects such as voids even if it is melt-molded under high temperature conditions. Therefore, even if the resin composition is coextruded with another thermoplastic resin having a high melting point, a multilayer structure having an excellent appearance can be obtained. Examples of the coextrusion method include a multi-manifold merging method T-die method, a feed block merging method T-die method, and an inflation method.

By secondary processing the multilayer structure obtained by the above-mentioned coextrusion, for example, the following secondary processed product can be obtained.
(1) Multi-layer stretched sheet or multi-layer stretched film obtained by stretching a multi-layer structure (sheet, film, etc.) in the uniaxial or biaxial direction and heat treatment (2) Rolling the multi-layer structure (sheet, film, etc.) Multi-layer rolled sheet or multi-layer rolled film (3) Multi-layer tray or multi-layer cup shape obtained by thermoforming (vacuum forming, pneumatic molding, vacuum pneumatic molding, etc.) of a multilayer structure (sheet, film, etc.) Container (4) Multi-layer bottle, multi-layer cup-shaped container, etc. obtained by stretch blow molding a multi-layer structure (pipe, etc.)

The molded product obtained by these secondary processes can be preferably used as a food container such as a deep-drawn container, a cup-shaped container, or a bottle.

Hereinafter, the present invention will be described in more detail by way of examples.

Example 1
(1) Synthesis of EVOH 100 kg of vinyl acetate and 3 kg of methanol (hereinafter referred to as MeOH) are charged in a 250 L pressure reaction tank equipped with a jacket, a stirrer, a nitrogen introduction port, an ethylene introduction port and an initiator addition port, and 30 Nitrogen was substituted in the system by nitrogen bubbling for 1 minute. Next, after adjusting the temperature in the reaction vessel to 75 ° C., ethylene was introduced so that the reaction vessel pressure (ethylene pressure) was 5.0 MPa, and 2,2'-azobis (4-methoxy-2, 4-Dimethylvaleronitrile) (“V-70” manufactured by Wako Pure Chemical Industries, Ltd.) was supplied as a 0.5 g / L methanol solution at 0.5 L / Hr for polymerization. The temperature was maintained at 75 ° C. during the polymerization, and the mixture was cooled after 5 hours to terminate the polymerization. After opening the reaction vessel and deethyleneing, the copolymer solution obtained from the upper part of the column filled with Rasichling was continuously supplied, methanol was blown from the lower part of the column, and methanol and unreacted vinyl acetate monomer were blown from the upper part of the column. The mixed vapor was allowed to flow out to obtain a methanol solution of ethylene-vinyl acetate copolymer (EVAc) from which the unreacted vinyl acetate monomer was removed from the bottom of the column. This EVAc methanol solution was charged into a saponification reactor, and caustic soda / methanol solution (80 g / L) was added so that the molar ratio of sodium hydroxide to the vinyl ester component in the copolymer was 0.4. Methanol was added to adjust the copolymer concentration to 20%. The temperature of this solution was raised to 60 ° C., and the reaction was carried out for about 6 hours while blowing nitrogen gas into the reactor, and then acetic acid and water were added to neutralize the reaction solution, and the reaction was stopped. The neutralized reaction solution was transferred from the reactor to a drum can and left at room temperature for 16 hours to be cooled and solidified into a cake. Then, the cake-shaped resin was deflated using a centrifuge (“H-130” rotation speed 1200 rpm manufactured by Japan Centrifuge Co., Ltd.). 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” manufactured by Toa Denpa Kogyo Co., Ltd.).

(2) Production of Hydrous EVOH Pellets The EVOH thus obtained was dried at 60 ° C. for 48 hours using a dryer. 20 kg of dried powdery EVOH was dissolved in 43 L of water / methanol solution (mass ratio: water / methanol = 4/6) at 80 ° C. for 12 hours with stirring. At this time, crotonaldehyde was added to the water / methanol solution together with the obtained EVOH. The amount of crotonaldehyde added was adjusted so that the content in the obtained EVOH composition pellets was 1.6 ppm. Next, the stirring was stopped, the temperature of the dissolution tank was lowered to 65 ° C., and the mixture was left for 5 hours to defoam the above-mentioned EVOH water / methanol solution. Then, it is extruded from a gold plate having a circular opening with a diameter of 3.5 mm into a water / methanol mixed solution (mass ratio: water / methanol = 9/1) at 5 ° C. 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. The water content of the obtained modified EVOH water-containing pellets was measured with a halogen moisture meter "HR73" manufactured by Mettler, and found to be 55% by mass.

(3) Production of EVOH Composition Pellet 40 kg of the water-containing EVOH pellet thus obtained and 150 L of ion-exchanged water were placed in a metal drum can having a height of 900 mm and an opening diameter of 600 mm, and washed at 25 ° C. for 2 hours with stirring. And the operation of removing the liquid was repeated twice. Next, 150 L of 1 g / L acetic acid aqueous solution was added to 30 kg of water-containing EVOH pellets, and the operation of washing and deliquessing was repeated twice while stirring at 25 ° C. for 2 hours. Furthermore, by adding 150 L of ion-exchanged water to 30 kg of hydrous EVOH pellets and repeating the operation of washing and deliquessing while stirring at 25 ° C. for 2 hours 6 times, impurities such as by-products generated in the saponification step can be removed. Removed. The water-containing pellet is put into an aqueous solution (bath ratio 20) having a sodium acetate concentration of 0.525 g / L, an acetic acid concentration of 0.8 g / L, and a phosphoric acid concentration of 0.007 g / L, and is immersed for 4 hours with regular stirring. rice field. This was deflated and dried at 80 ° C. for 3 hours and at 105 ° C. for 16 hours to obtain EVOH composition pellets containing acetic acid, sodium salt and phosphorus compound.

(4) Alkenyl group content, ethylene unit content and saponification degree The EVOH composition pellets obtained in (3) above are treated with chloroform for 48 hours in a Soxhlet extractor to extract additives and the like in EVOH. , Removed and purified. The purified EVOH is dissolved in dimethyl sulfoxide (DMSO) _-d6 containing tetramethylsilane as an internal standard substance and tetrafluoroacetic acid (TFA) as an additive, and ¹ H-NMR at 500 MHz (manufactured by Nippon Denshi Co., Ltd .: When measured at 80 ° C. using "GX-500"), a peak based on hydrogen of a methylene group at about 1 to 1.8 ppm, a peak based on hydrogen of a methyl group constituting a vinyl acetate unit near 2 ppm, about 3 A hydrogen-based peak of the methoxy group was observed at ~ 3.15 ppm, and a hydrogen-based peak constituting the methine group of the vinyl alcohol unit was observed at about 3.15 to 4.15 ppm. From the NMR spectrum, the content of ethylene units was 32 mol%, the degree of saponification was 99.98 mol%, and the content of units containing methoxy groups was 0.0049 mol%.

(5) MFR
The MFR (temperature 210 ° C., load 2160 g) of the EVOH composition pellet obtained in (2) above was measured according to JIS K 7210 and found to be 4.0 g / 10 minutes.

(6) Quantification of alkali metal ion (C) 0.5 g of the EVOH composition pellet obtained in (3) above is placed in a pressure vessel made of Teflon (registered trademark), 5 mL of concentrated nitric acid is added thereto, and the temperature is 30 minutes at room temperature. Disassembled. After decomposition, the lid was closed, and the mixture was further decomposed by heating at 150 ° C. for 10 minutes and then at 180 ° C. for 5 minutes using a wet decomposition device (“MWS-2” manufactured by Actac), and then cooled to room temperature. This treatment solution was transferred to a 50 mL volumetric flask (manufactured by TPX) and measured with pure water to prepare a sample solution for measurement. The content of the metal element of this sample solution was determined by an ICP emission spectrophotometer (“OPTIMA4300DV” manufactured by PerkinElmer Co., Ltd.). The content of sodium ions in the EVOH composition pellet was 150 ppm in terms of sodium element.

(7) Quantification of unsaturated aliphatic aldehyde (B) 50 mL of 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) in 200 mg of 2,4-dinitrophenylhydrazine (DNPH) solution of 50% by mass. , Acetic acid (11.5 mL) and ion-exchanged water (8 mL) were added to prepare a DNPH-adjusted solution. Then, 1 g of the EVOH composition pellet obtained in (3) above was added to 20 mL of the DNPH-adjusted solution, and the mixture was stirred and dissolved at 35 ° C. for 1 hour. Acetonitrile was added to this solution to precipitate EVOH, and the solution was filtered and concentrated to obtain an extracted sample. Quantitative analysis of this extracted sample by high performance liquid chromatography revealed that the content of crotonaldehyde in the EVOH composition pellets was 1.6 ppm. For quantification, a calibration curve prepared using a standard obtained by reacting crotonaldehyde with a DNPH preparation solution was used.

(8) Moisture content of EVOH composition After heating 20 g of EVOH composition pellets at 120 ° C. for 24 hours in a hot air dryer, the water content of the EVOH composition pellets was determined using the following formula and found to be 0.25 mass. %Met.
Moisture content (mass%) = ((sample mass-mass after drying) / sample mass) x 100

(9) Preparation of Single Layer Film The EVOH composition pellets obtained in (3) above were formed into a film to obtain a single layer film. A film was formed using a 20 mm extruder "D2020" (D (mm) = 20, L / D = 20, compression ratio = 2.0, screw: full flight) manufactured by Toyo Seiki Seisakusho Co., Ltd. under the following conditions. The thickness was adjusted to 60 μm by changing the take-up roll speed of the formed single-layer film.
Extrusion temperature: Supply unit / compression unit / measurement unit / die
= 170/210/210/210 ° C
Screw rotation speed: 40 rpm
Pick-up roll temperature: 80 ° C

(10) Terahertz spectroscopic measurement The 60 μm-thick single-layer film obtained in (9) above was heated at 80 ° C. in a hot air dryer for 10 minutes and then dried in a vacuum dryer for 1 month. After removing the single-layer film from the vacuum dryer, it is immediately absorbed by performing terahertz spectroscopic measurement (1 to 8 THz) at 25 ° C. using a far-infrared Fourier transform spectrophotometer (“FARIS” manufactured by JASCO Corporation). I got a curve. The vacuum-dried single-layer film was humidified in a constant temperature and humidity chamber at 25 ° C. and a relative humidity of 11, 22, 33, 44, 55, 66, 76, 86, 90 or 100% for one month. After taking out the monolayer film from the constant temperature and humidity chamber, terahertz spectroscopy (1 to 8 THz) was immediately performed in the same manner as described above to obtain an absorption curve at each relative humidity. The difference between the absorption curve at relative humidity 11, 22, 33, 44, 55, 66, 76, 86, 90 or 100% and the difference between the absorption curve at 0% relative humidity is standardized by the thickness of the film, and the difference at each relative humidity. A spectrum was obtained. FIG. 1 shows a difference spectrum obtained by terahel spectroscopic measurement of a single-layer film at each relative humidity. For these difference spectra (1 to 8 THz), the numerical data of each spectrum is converted into a comma-separated value (CSV) file, and the time-dependent correlation spectrum is obtained using two-dimensional correlation analysis software (2D-size). Obtained. Here, assuming that the increase in the value of the difference spectrum due to the increase in relative humidity is ahead of the frequency y (Y-axis) in the frequency x (X-axis), the value of the time-dependent correlation spectrum (Z-axis). Was plotted. FIG. 2 shows an extraordinary correlation spectrum obtained from the difference spectrum. The value of the frequency x (X-axis) at which the value of the extraordinary correlation spectrum (Z-axis) has the maximum positive value was 5.4 THz.

(11) Appearance Evaluation The EVOH composition pellets obtained in (3) above were formed into a film to obtain a single-layer film. A film was formed using a 20 mm extruder "D2020" (D (mm) = 20, L / D = 20, compression ratio = 2.0, screw: full flight) manufactured by Toyo Seiki Seisakusho Co., Ltd. under the following conditions. .. The thickness was adjusted to 20 μm by changing the take-up roll speed of the formed single-layer film. When the appearance (void) of the obtained single-layer film was visually evaluated according to the following evaluation criteria, it was judged as C.
<Film formation conditions>
Extrusion temperature: Supply unit / compression unit / measurement unit / die
= 180/290/290/290 ° C.
Screw rotation speed: 40 rpm
Pick-up roll temperature: 80 ° C
<Evaluation>
A: No voids B: Slightly confirmed voids C: Multiple voids confirmed D: Many voids confirmed

Example 2
EVOH was synthesized in the same manner as in (1) of Example 1 except that the amount of MeOH was 10 kg, the supply amount of the initiator was 1.0 L / Hr, and the polymerization temperature was 80 ° C. Hydrous EVOH pellets were produced in the same manner as in (2) of Example 1 except that the amount of crotonaldehyde added was adjusted so that the content in the obtained EVOH composition pellets was 1.8 ppm. The EVOH composition pellets and the single-layer film were prepared and evaluated in the same manner as in Example 1 except that the hydrous EVOH pellets thus obtained were used. The results are summarized in Table 1.

Example 3
EVOH was synthesized in the same manner as in (1) of Example 1 except that the amount of MeOH was 5 kg, the ethylene pressure was 3.8 MPa, and the polymerization temperature was 80 ° C. Hydrous EVOH pellets were produced in the same manner as in (2) of Example 1 except that crotonaldehyde was not added. The EVOH composition pellets and the single-layer film were prepared and evaluated in the same manner as in Example 1 except that the hydrous EVOH pellets thus obtained were used. The results are summarized in Table 1.

Comparative Example 1
The amount of MeOH was 23 kg, benzoyl peroxide was used instead of V-70, 13 g of initiator was charged, the ethylene pressure was 4.1 MPa, the polymerization temperature was 67 ° C., and the saponification reaction time was 4 hours. Except for this, EVOH was synthesized in the same manner as in (1) of Example 1. Hydrous EVOH pellets were produced in the same manner as in (2) of Example 1 except that the amount of crotonaldehyde added was adjusted so that the content in the obtained EVOH composition pellets was 2.4 ppm. The EVOH composition pellets and the single-layer film were prepared and evaluated in the same manner as in Example 1 except that the hydrous EVOH pellets thus obtained were used. The results are summarized in Table 1.

Comparative Example 2
Except for the fact that the amount of MeOH was 21 kg, 2,2'-azoisobutyronitrile was used instead of V-70, 5 g of the initiator was charged, the ethylene pressure was 4.3 MPa, and the polymerization temperature was 70 ° C. , EVOH was synthesized in the same manner as in (1) of Example 1. Hydrous EVOH pellets were produced in the same manner as in (2) of Example 1 except that crotonaldehyde was not added. The EVOH composition pellets and the single-layer film were prepared and evaluated in the same manner as in Example 1 except that the hydrous EVOH pellets thus obtained were used. The results are summarized in Table 1.

Claims (6)

A resin composition containing an ethylene-vinyl alcohol copolymer (A) as a main component.
The ethylene-vinyl alcohol copolymer (A) has an ethylene unit content of 20 to 55 mol% and a saponification degree of 90 mol% or more.
The ethylene-vinyl alcohol copolymer (A) contains 0.0005 to 0.0052 mol% of an alkoxyl group.
Humidity is controlled at a relative humidity of 0% from the absorption curve obtained by irradiating a single-layer film having a thickness of 60 μm made of the resin composition, which has been adjusted at each of the following relative humidities, with terahertz light in the range of 1 to 8 THz. In contrast to the difference spectrum obtained by subtracting the absorption curve obtained by irradiating the single-layer film with terahertz light in the range of 1 to 8 THz, the frequency in the time-dependent correlation spectrum obtained by using the two-dimensional correlation spectroscopy. When the case where the value of the difference spectrum corresponding to the frequency x (X axis) increases earlier than the value of the difference spectrum corresponding to y (Y axis) is positive, the value of the time-correlation spectrum (Z axis). ) Is a positive maximum value, and the value of x is 5.2 THz or more and less than 6.0 THz.
Relative humidity (%): 11, 22, 33, 44, 55, 66, 76, 86, 90, 100 The resin composition according to claim 1 , which contains 0.05 to 90 ppm of unsaturated aliphatic aldehyde (B). The resin composition according to claim 2 , wherein the unsaturated aliphatic aldehyde (B) is at least one selected from the group consisting of crotonaldehyde, 2,4-hexadienal and 2,4,6-octatrienal. thing. The resin composition according to any one of claims 1 to 3 , which contains 10 to 500 ppm of an alkali metal ion (C). A molded product containing the resin composition according to any one of claims 1 to 4 . A multilayer structure having a layer made of the resin composition according to any one of claims 1 to 4 .

Images