JP2001164059A - Resin composition comprising ethylene-vinyl alcohol copolymer having excellent long run property and multilayer structure using the composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin composition composed of an ethylene-vinyl alcohol copolymer having excellent appearance and long-run properties in melt molding, slight discoloration in recovery and excellent interlaminar bonding when made into a laminate. SOLUTION: This resin composition is characterized in that the resin composition comprises an ethylene-vinyl alcohol copolymer, MFR (10.9 kg load at 230 deg.C) of the resin composition shows the minimum value within 10 hours from the start of heating when the resin composition is heated in an nitrogen atmosphere at 220 deg.C and shows the maximum within 100 hours after showing the minimum and the resin composition contains 50-500 ppm of a carboxylic acid (A) having <75 molecular weight, 50-500 ppm calculated as metal element of an alkali metal salt (B), 10-120 ppm calculated as metal element of an alkaline earth metal salt (C), 10-200 ppm calculated as phosphate radical of a phosphorus compound (D) and 50-2,000 ppm calculated as boron element of a boron compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a laminate which is particularly excellent in long-run property at the time of melt molding, has low appearance of gels and bumps, has excellent appearance, has good recoverability, has little coloration at the time of recovery, and is used as a laminate. The present invention relates to a resin composition comprising an ethylene-vinyl alcohol copolymer having excellent interlayer adhesion at the time and a laminate using the same.

[0002]

2. Description of the Related Art Ethylene-vinyl alcohol copolymer (hereinafter sometimes abbreviated as EVOH) is a useful polymer material excellent in oxygen shielding property, oil resistance, non-charging property, mechanical strength and the like. Widely used as various packaging materials such as sheets and containers. Such packaging materials are usually manufactured by melt molding, and have a long run property during melt molding (a molded article free of fish eyes and stripes can be obtained even when molding for a long time), and the appearance of the molded article (less colored) And a molded product in which generation of fish eyes is not observed. In recent years, recyclability has also become an important issue. Even when an EVOH molded product is collected, melt-molded again, and the heat history is repeated, the recoverability (recovered E
There is a demand for EVOH that has good VOH moldability) and has little coloration during recovery.

[0003] EVOH is usually formed by melt molding. In order to improve productivity, it is preferable to operate the molding machine continuously for a long period of time. However, depending on the shape of the molding machine, a part of the EVOH may stay for a long time in the resin flow path. When the EVOH in a part is gelled by prolonged heating, adhesion of thermally degraded resin to the molding machine die, occurrence of mixing of gels and lumps in the product, or appearance due to uneven thickness, streaks, etc. Failure may occur.
Further, when the EVOH in the staying portion is violently decomposed by heating for a long time, coloring, foaming, etc. are caused, and the appearance of the molded product is also deteriorated. Also, when a molded product made of EVOH is recovered, the EVO is also required to accumulate heat history.
H was gelled or decomposed, causing a problem in the appearance of the molded product. For this reason, EVOH which has little occurrence of gelation or decomposition even during long-time heating has been desired.

Furthermore, in order to impart mechanical strength, moisture resistance, heat sealing properties, and the like, a laminated body is generally formed by co-extrusion with a base material such as a polyolefin resin via an adhesive layer. Also, the interlayer adhesion of the laminate is important. That is, the appearance of the molded product, the long run property during melt molding,
It is necessary to sufficiently satisfy the recoverability and the interlayer adhesion of the laminate.

Therefore, as a countermeasure, the following proposals have been made to produce an excellent molded product by treating an ethylene-vinyl alcohol copolymer with various acids or metal salts.

For example, (1) in order to improve the long run property and the appearance typified by gel buttes, 0.0005 to 0.05% by weight (in terms of metal) of a metal salt belonging to Group II of the periodic table. Containing 0.002 to 0.2% by weight of an acid having a pKa of 3.5 or more and a boiling point of 180 ° C. or more, and 0.01 to 0.2% by weight of an acid having a pKa of 3.5 or more and a boiling point of 120 ° C. or less; An EVOH composition exhibiting specific flow characteristics has been disclosed (JP-A-64-66262). (2) In order to improve the appearance, long run property, stretching unevenness, and interlayer adhesion, the boron compound is 0.001 to 1% by weight (in terms of boron), acetic acid is 0.05% by weight or less, and acetate is 0.001% or less.
An EVOH composition containing 0.0005 to 0.05% by weight (in terms of metal) and / or 0.0005 to 0.05% by weight (in terms of phosphate group) of a phosphate is disclosed (WO99 / 05).
213). (3) In order to improve the appearance, long-run property and interlayer adhesion, the boron compound is 0 to 1% by weight (in terms of boron), acetic acid is 0 to 0.05% by weight, and sodium acetate is 0 to 0% by weight.
0.1% by weight (in terms of metal), 0.001 to 0.02% by weight of magnesium acetate and / or calcium acetate
An EVOH composition containing (in terms of metal) is disclosed (EP-906924). (4) In order to improve the long-run property at the time of melt molding and the physical properties such as fish eye, transparency, and streaks of a molded product, 0.05 to 0.3% by weight (in terms of boron) of a boron compound and 0 of sodium acetate are used. .001-
0.02% by weight (in terms of metal), magnesium acetate is 0.1%.
EVOH containing 001 to 0.02% by weight (in terms of metal)
A composition is disclosed (JP-A-11-60874). (5) An EVOH composition containing a hydroxycarboxylic acid and / or a salt thereof, an alkali metal salt, an alkaline earth metal salt, a phosphate, and a boron compound in order to improve coloring, appearance, and interlayer adhesion is disclosed. (JP-A-10-67898). Further, the publication discloses, as Comparative Example 7, acetic acid 123 with respect to 100 parts by weight of EVOH.
0 ppm (as acetate), sodium acetate 350 pp
m (in terms of metal), magnesium acetate 50 ppm (in terms of metal), potassium dihydrogen phosphate 30 ppm (in terms of phosphorus),
Although a resin composition containing 40 ppm of boric acid (in terms of boron) is disclosed, a film formed from such a composition is excellent in interlayer adhesion, but has a problem in the appearance of the film such as coloring and lumps. It is described that there is.

[0007]

However, in the above prior arts (1) to (5), the long run property at the time of melt molding, the appearance of the molded product, the recoverability, the color resistance at the time of recovery, and the laminate are described. Nothing has been found that simultaneously satisfies all of the interlayer adhesive properties at the same time, and at the present time when molded products with advanced functions and quality are required, a satisfactory level has been reached. It is not at present.

[0008]

An object of the present invention is to provide a resin composition comprising an ethylene-vinyl alcohol copolymer, wherein the resin composition is heated at 220 ° C. under a nitrogen atmosphere. The MFR of the resin composition (230 ° C., 1
0.9 kg load) shows a local minimum value within 10 hours from the start of heating, and shows a local maximum value (MFRmax) within 100 hours after showing the local minimum value. 50 to 500 ppm, the alkali metal salt (B) is 50 to 500 ppm in terms of the metal element, and the alkaline earth metal salt (C) is 10 to 120 in terms of the metal element.
ppm, phosphate compound (D) is 10 to 2 in terms of phosphate group.
00 ppm, boron compound (E) is 5
The problem is solved by a resin composition containing 0 to 2000 ppm and satisfying the following formula (1). 0.5 ≦ MFRmax / MFR0 ≦ 45 (1) where, MFRmax: MFR of the resin composition when the resin composition is heated at 220 ° C. under a nitrogen atmosphere (230 ° C., 1
Maximum value of 0.9 kg load) MFR0: MF of resin composition not subjected to heat treatment
R (230 ° C, 10.9kg load)

That is, the present invention relates to a resin composition comprising an ethylene-vinyl alcohol copolymer, wherein when the resin composition is heated at 220 ° C. under a nitrogen atmosphere, the MFR (230 ° C.) Carboxylic acid (A) having a molecular weight of less than 75 (10.9 kg load) shows a minimum value within 10 hours from the start of heating, and shows a maximum value (MFRmax) within 100 hours after showing the minimum value. 50 to 500 ppm, the alkali metal salt (B) is 50 to 500 ppm in terms of a metal element, and the alkaline earth metal salt (C)
Is contained in an amount of 10 to 120 ppm in terms of a metal element, the phosphoric acid compound (D) in an amount of 10 to 200 ppm in terms of a phosphate group, the boron compound (E) in an amount of 50 to 2000 ppm in terms of a boron element, and satisfies the following formula (1). The present invention relates to a characteristic resin composition. 0.5 ≦ MFRmax / MFR0 ≦ 45 (1) where, MFRmax: MFR of the resin composition when the resin composition is heated at 220 ° C. under a nitrogen atmosphere (230 ° C., 1
Maximum value of 0.9 kg load) MFR0: MF of resin composition not subjected to heat treatment
R (230 ° C, 10.9kg load)

[0010] In a preferred embodiment, the carboxylic acid (A) having a molecular weight of less than 75 is acetic acid.

In a preferred embodiment, the alkaline earth metal salt (C) of the resin composition of the present invention is a magnesium salt and / or a calcium salt, and is 10 to 60 in terms of metal.
20 ppm in terms of magnesium salt and / or metal
カ ル シ ウ ム 120 ppm calcium salt.

In a preferred embodiment, the resin composition of the present invention satisfies the following formula (2). [B (μmol / g) + C (μmol / g)] / [A (μmol / g) + D (μmol / g)] = 1 to 15 (2) where A: molecular weight of 75 per unit weight of resin composition
B: Content of carboxylic acid (A) less than (μmol / g) B: Content of alkali metal salt (B) per unit weight of resin composition (μmol / g) C: Alkali per unit weight of resin composition Content of earth metal salt (C) (μmol / g) D: Phosphoric acid compound (C) per unit weight of resin composition
Content (μmol / g)

Further, in a preferred embodiment, the resin composition of the present invention contains 0.1 part by weight of a lubricant based on 100 parts by weight of EVOH.
005 to 1 part by weight.

In a preferred embodiment, the pellets comprising the resin composition of the present invention are obtained by adhering 0.005 to 0.5 parts by weight of a lubricant to 100 parts by weight of the resin composition on the outer surface of the pellets. .

[0015] The present invention also relates to a multilayer structure obtained by laminating a thermoplastic resin on at least one surface of a layer comprising the above resin composition.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The EVOH used in the present invention is preferably obtained by saponifying an ethylene-vinyl acetate copolymer, and among them, the ethylene content is preferably 3 to 70 mol%. . From the viewpoint of obtaining a molded product having excellent gas barrier properties and melt moldability, the ethylene content is preferably 10 to 65 mol%, more preferably 20 mol%.
Preferably, it is between about 65 mol% and optimally between 25 and 60 mol%. Further, the saponification degree of the vinyl ester component is preferably 80% or more, and more preferably 95% or more, and further preferably 99% or more, from the viewpoint of obtaining a molded article having excellent gas barrier properties. If the ethylene content exceeds 70 mol%, there is a possibility that the barrier properties, printability and the like may be insufficient. If the saponification degree is less than 80%,
There is a possibility that barrier properties, thermal stability, and moisture resistance may deteriorate.

On the other hand, EVOH having an ethylene content of 3 to 20 mol% is suitably used as EVOH having water solubility, and such an EVOH aqueous solution has excellent barrier properties and coating stability, and is an excellent coating material. Used.

When copolymerizing ethylene and vinyl acetate, other fatty acid vinyl esters (such as vinyl propionate and vinyl pivalate) can also be used in combination. EVOH can contain 0.0002 to 0.2 mol% of a vinylsilane compound as a copolymerization component. Here, as the vinylsilane-based compound, for example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri (β-methoxy-ethoxy) silane,
γ-methacryloxypropylmethoxysilane. Among them, vinyltrimethoxysilane and vinyltriethoxysilane are preferably used.

Hereinafter, a method for producing EVOH will be specifically described. The polymerization of ethylene and vinyl acetate is not limited to solution polymerization, but may be any of solution polymerization, suspension polymerization, emulsion polymerization, bulk polymerization, and may be any of a continuous system and a batch system. For example, the polymerization conditions in the case of batch type solution polymerization are as follows.

Solvent: Alcohols are preferred, but other organic solvents (such as dimethyl sulfoxide) that can dissolve ethylene, vinyl acetate and ethylene-vinyl acetate copolymer can also be used. As the alcohols, methyl alcohol, ethyl alcohol, propyl alcohol, n-butyl alcohol, t-butyl alcohol and the like can be used, and methyl alcohol is particularly preferable. Catalyst; 2,2-azobisisobutyronitrile, 2,2-
Azobis- (2,4-dimethylvaleronitrile), 2,
2-azobis- (4-methyl-2,4-dimethylvaleronitrile), 2,2-azobis- (4-methoxy-2,
4-dimethylvaleronitrile), 2,2-azobis-
Azonitrile-based initiators such as (2-cyclopropylpropionitrile) and isobutyryl peroxide, cumyl peroxy neodecanoate, diisopropyl peroxy carbonate, di-n-propyl peroxy dicarbonate, t-butyl peroxy neo Decanoate, lauroyl peroxide, benzoyl peroxide,
Organic peroxide-based initiators such as t-butyl hydroperoxide and the like can be used. Temperature: 20-90 ° C, preferably 40-70 ° C. Time; 2 to 15 hours, preferably 3 to 11 hours. Polymerization rate; 10 to 90% based on the charged vinyl ester;
Preferably 30-80%. Resin content in solution after polymerization; 5 to 85%, preferably 20
~ 70%. Ethylene content in the copolymer; preferably 3 to 70 mol%, more preferably 25 to 60 mol%.

It is to be noted that, in addition to ethylene and vinyl acetate, monomers copolymerizable therewith, for example, α-olefins such as propylene, isobutylene, α-octene, α-dodecene; acrylic acid, methacrylic acid, crotonic acid, maleic acid Acids, unsaturated acids such as itaconic acid or anhydrides, salts or mono- or dialkyl esters; nitriles such as acrylonitrile and methacrylonitrile; amides such as acrylamide and methacrylamide; ethylene sulfonic acid, allyl sulfonic acid; Olefin sulfonic acid such as methallyl sulfonic acid or a salt thereof; alkyl vinyl ethers, vinyl ketone, N-vinyl pyrrolidone, vinyl chloride, vinylidene chloride, and the like can be coexisted in small amounts.

After the polymerization for a predetermined time has reached a predetermined polymerization rate, a polymerization inhibitor is added if necessary, and unreacted ethylene gas is removed by evaporation, and then unreacted vinyl acetate is expelled. As a method of driving out unreacted vinyl acetate from the ethylene-vinyl acetate copolymer from which ethylene has been removed by evaporation,
For example, the copolymer solution is continuously supplied at a constant rate from the top of the tower filled with Raschig rings, and an organic solvent vapor such as methanol is blown from the bottom of the tower and an organic solvent such as methanol and unreacted vinyl acetate are blown from the top of the tower. A method of distilling out the mixed vapor and taking out the copolymer solution from which unreacted vinyl acetate has been removed from the bottom of the column is adopted.

An alkali catalyst is added to the copolymer solution from which unreacted vinyl acetate has been removed to saponify the vinyl acetate component in the copolymer. The saponification method can be either a continuous type or a batch type. As the alkali catalyst, sodium hydroxide, potassium hydroxide, alkali metal alcoholate and the like are used. For example, the saponification conditions in the case of the batch system are as follows. Concentration of the copolymer solution; 10 to 50%. Reaction temperature; Amount of catalyst used: 0.02 to 0.6 equivalent (per vinyl acetate component). Time; 1-6 hours. Although the degree of saponification after the saponification reaction varies depending on the purpose, it is preferably 80% or more of the vinyl acetate component, more preferably 95%.
Above, more preferably 99% or more. The saponification degree can be arbitrarily adjusted depending on the conditions.

Since the ethylene-vinyl alcohol copolymer after the reaction contains an alkali catalyst, by-product salts, and other impurities, it is preferable to remove these by neutralizing and washing as necessary.

The resin composition comprising the EVOH of the present invention comprises:
When heated at 220 ° C. in a nitrogen atmosphere, the MFR (230 ° C., 10.9 kg load) of the resin composition shows a minimum value within 10 hours from the start of heating, and shows a minimum value within 1 hour.
It is characterized by showing a maximum value (MFRmax) within 00 hours, and it is extremely important to satisfy the following expression (1). 0.5 ≦ MFRmax / MFR0 ≦ 45 (1) where MFRmax: the resin composition is 2 in a nitrogen atmosphere.
The MFR of the resin composition when heated at 20 ° C. (230
Maximum temperature MFR0 of 10.9 ° C., 10.9 kg load): MFR of resin composition not subjected to heat treatment (230 ° C., 10.3 kg).
(9 kg load) The resin composition comprising the EVOH of the present invention exhibiting such a melting behavior has a small amount of the resin attached to the die during melt molding. Further, even during extremely long-time melt molding, it is possible to suppress gels and bumps of a molded product (such as a film). That is, the resin composition comprising the EVOH of the present invention is extremely excellent in long-run property. On the other hand, when the resin composition made of EVOH does not have the above-mentioned configuration (Comparative Example 3: see FIG. 1), not only the effect of reducing the amount of die attached is not obtained, but also long-term continuous operation is performed. It is clear that the number of generated gels and butters increases in the case of the above.

Further, as a result of detailed studies by the present inventors, it is clear that the frequency of occurrence of gels and butters in the resin composition composed of EVOH without the above-mentioned structure may increase rapidly during long-term operation. Became. This rapid increase in the frequency of gel spots is not permanent, and usually, after a few minutes to several tens of minutes have passed since the frequency of the gel spots increased rapidly, the normal level of gel spots was resumed. Although the frequency of occurrence reverts to the frequency of occurrence, the appearance of the molded article when the frequency of occurrence of gel / bubbles suddenly increases is poor, and a product which can withstand practical use cannot be usually obtained. However, by using the resin composition of the present invention developed by the present inventors, it has become possible to effectively suppress a rapid increase in the frequency of occurrence of gel and butter even during long-time melt molding. As described above, by using the resin composition of the present invention, long-time molding can be performed without problems even in applications requiring an extremely high appearance, such as a film, and productivity can be improved. From this viewpoint, the present invention is significant.

As described above, the resin composition comprising EVOH of the present invention satisfies the following formula (1). 0.5 ≦ MFRmax / MFR0 ≦ 45 (1) where, MFRmax: MFR of the resin composition when the resin composition is heated at 220 ° C. under a nitrogen atmosphere (230 ° C., 1
Maximum value MFR0 of 0.9 kg load): MFR (230 ° C., 10.9 kg) of the resin composition that has not been subjected to the heat treatment
Load) The lower limit of MFRmax / MFRO is more preferably 0.7.
And more preferably 1. Also, MFRma
The upper limit of x / MFRO is more preferably 35, more preferably 25, even more preferably 20,
Optimally it is 10. When the value of MFRmax / MFR0 is in the above range, the amount of the thermally degraded resin adhered to the molding machine die during the melt molding of the resin composition and the generation of gel / bubbles of the molded product are small, and the generation of gel / bubbles is generated. It is possible to obtain a resin composition composed of EVOH which is excellent in coloring resistance and whose frequency fluctuation is suppressed.

When the value of MFRmax / MFR0 is less than 0.5, the amount of resin adhered to the molding machine die increases, the long-run property deteriorates, and the effect of suppressing the fluctuation of the frequency of occurrence of gels and bumps is insufficient. It becomes something. Also, MFRmax
It is clear from Comparative Example 4 that when the value of / MFR0 exceeds 45, coloring due to decomposition of EVOH becomes remarkable and the appearance becomes poor.

The carboxylic acid (A) having a molecular weight of less than 75 used in the present invention preferably has a pKa at 25 ° C. of 3.5 or more. If the pKa at 25 ° C. is less than 3.5, it may be difficult to control the pH of the resin composition comprising EVOH, and the coloring resistance and interlayer adhesion may be unsatisfactory. Examples of the carboxylic acid (A) having a molecular weight of less than 75 include formic acid, acetic acid, and propionic acid. From the viewpoint of cost advantages, acidity is appropriate, and the pH of the resin composition is easily controlled. Acetic acid is particularly preferred.

The resin composition of the present invention has a molecular weight of 75.
Carboxylic acid (A) content of less than 50-500 pp
m. The lower limit of the content of the carboxylic acid (A) having a molecular weight of less than 75 is more preferably 75 ppm or more, and further preferably 100 ppm or more. In addition, molecular weight 75
The upper limit of the content of the carboxylic acid (A) less than 4 is preferably 4
It is at most 00 ppm, more preferably at most 300 ppm. When the content of the carboxylic acid (A) having a molecular weight of less than 75 is less than 50 ppm, coloring at the time of melting is remarkable.
If it exceeds 500 ppm, the interlayer adhesion deteriorates.

The content of the alkali metal salt (B) in the resin composition of the present invention is 50 to 500 ppm, preferably 100 to 300 ppm in terms of metal. 50pp
If it is less than m, the adhesion to other resins is poor, and there is a problem particularly in the interlayer adhesion during coextrusion molding. Also, 500p
When it exceeds pm, coloring at the time of melting is remarkable. The alkali metal salt (B) is not particularly limited, and examples thereof include a sodium salt and a potassium salt. The type of anion of the alkali metal salt is not particularly limited, but an acetate anion or a phosphate anion is preferable.

The content of the alkaline earth metal salt (C) in the resin composition of the present invention is 10 to 120 ppm, preferably 20 to 100 ppm in terms of metal. That the content of the alkaline earth metal salt (C) is in such a range,
It is extremely important in controlling the variation of the MFR of the ethylene-vinyl alcohol copolymer composition over time. 10p
If it is less than pm, it is inferior in long run property and 120 ppm
If it exceeds, coloring at the time of melting is remarkable.

The alkaline earth metal salt (C) is not particularly restricted but includes magnesium salt, calcium salt, barium salt, beryllium salt and the like, and magnesium salt and calcium salt are particularly preferred. Although the anion species of the alkaline earth metal salt is not particularly limited, acetate anions and phosphate anions are preferred. When the alkaline earth metal salt (C) in the resin composition of the present invention is a magnesium salt, its preferable content is 10 to 60 ppm in terms of metal.
And more preferably 20 to 50 ppm. When the alkaline earth metal salt (C) in the resin composition is a calcium salt, a suitable content is 20 to 12 in terms of metal.
0 ppm, more preferably 40 to 100 ppm.

The content of the phosphate compound (D) in the resin composition of the present invention is 10 to 500 ppm in terms of phosphate group.
It is. The lower limit of the content of the phosphate compound (D) is preferably at least 20 ppm, more preferably at least 30 ppm, and most preferably at least 50 ppm. The upper limit of the content of the phosphoric acid compound (D) is preferably 250 ppm.
Or less, more preferably 150 ppm or less. By containing the phosphoric acid compound in such a range, it is possible to obtain a resin composition which is less colored, has excellent long-run properties and gives a good appearance of a molded article. When the content of the phosphoric acid compound (D) is less than 10 ppm, coloring at the time of melt molding is remarkable and appearance is reduced. In particular, when the heat history is repeated, the tendency is remarkable, so that the resin composition has poor recoverability. If it exceeds 500 ppm, the occurrence of gel and butter in the molded product becomes remarkable, and the appearance is reduced.
Examples of the phosphoric acid compound (D) include, but are not limited to, various acids such as phosphoric acid and phosphorous acid, and salts thereof. The phosphate may be contained in any form of a first phosphate, a second phosphate, and a third phosphate, and the cation species is not particularly limited. Preferred are alkali metal salts and alkaline earth metal salts. Among them, it is preferable to add the phosphate compound (D) in the form of sodium dihydrogen phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate, and dipotassium hydrogen phosphate.

The boron compound (E) used in the present invention includes, but is not limited to, boric acids, borate esters, borates, borohydrides and the like. Specifically, the boric acids include orthoboric acid, metaboric acid, tetraboric acid, and the like, and the borate esters include triethyl borate, trimethyl borate, and the like.
Examples of the borate include alkali metal salts, alkaline earth metal salts, and borax of the above-mentioned various boric acids. Of these compounds, orthoboric acid (hereinafter sometimes simply referred to as boric acid) is preferred. When a boron compound is added to a resin composition composed of EVOH, even when EVOH having a low degree of polymerization is used, it is possible to increase the melt viscosity. It is also possible to suppress the generation of gel and butter and improve the long-run property.

The content of the boron compound (E) in the resin composition of the present invention is 50 to 2000 ppm in terms of boron. The lower limit of the content of the boron compound (E) is more preferably 100 ppm or more, and still more preferably 150 ppm.
ppm or more. The upper limit of the content of the boron compound (E) is preferably 1500 ppm or less, more preferably 1000 ppm or less in terms of boron.
If the amount is less than 50 ppm, the effect of improving the long-run property by adding the boron compound (E) cannot be obtained, and
If it exceeds pm, gelation is likely to occur, resulting in poor moldability, and the appearance of the molded article will deteriorate.

The resin composition comprising the EVOH of the present invention comprises:
All of the carboxylic acid (A), alkali metal salt (B), alkaline earth metal salt (C), phosphoric acid compound (D) and boron compound (E) having a molecular weight of less than 75 are essential components. The effect of the present invention can be obtained for the first time by containing the above-described specific amount. As will be apparent from examples and comparative examples described later in the present specification, in the second resin composition of the present invention, the above components (A), (B), (C), (D) and Even if any one of (E) is missing, sufficient performance cannot be obtained.

In the present invention, when the following expression (2) is satisfied, the effects of the present invention can be more remarkably obtained, which is preferable. [B (μmol / g) + C (μmol / g)] / [A (μmol / g) + D (μmol / g)] = 1 to 15 (2) where A: molecular weight of 75 per unit weight of resin composition
B: Content of carboxylic acid (A) less than (μmol / g) B: Content of alkali metal salt (B) per unit weight of resin composition (μmol / g) C: Alkali per unit weight of resin composition Content of earth metal salt (C) (μmol / g) D: Phosphoric acid compound (C) per unit weight of resin composition
Content (μmol / g)

By increasing the contents of the alkali metal salt (B) and the alkaline earth metal (C) in the resin composition comprising EVOH, the adhesiveness of the resin composition and the effect of reducing the amount of die attached are improved. , MFRmax / MFRO generally increase. However, the addition of excess alkali metal salt (B) and alkaline earth metal salt (C)
In addition to deteriorating the color resistance, the decomposition of the resin composition adversely affects the low odor.

On the other hand, by increasing the content of the carboxylic acid (A) having a molecular weight of less than 75 and the content of the phosphoric acid compound (D) in the resin composition comprising EVOH, the coloring resistance of the molded product can be improved. Yes, MFRmax / MFRO generally decreases. In addition, it is also possible to improve long-run property by adding an appropriate amount of a carboxylic acid (A) having a molecular weight of less than 75 and a phosphoric acid compound (D). However, the addition of an excessive amount of the carboxylic acid (A) and the phosphoric acid compound (D) having a molecular weight of less than 75 causes an increase in gels and bumps, and further reduces the adhesiveness of the resin composition. Thus, the effects of the carboxylic acid (A), alkali metal salt (B), alkaline earth metal salt (C) and phosphoric acid compound (D) having a molecular weight of less than 75 on the properties of the resin composition are mutually reciprocal. There is a relationship, and by blending them in a well-balanced manner, a resin composition composed of EVOH exhibiting high performance in all aspects of long-running properties, appearance properties, recoverability, coloring resistance and interlayer adhesion during melt molding. It is possible to get things.

Here, when the resin composition of the present invention satisfies the above formula (2), it is possible to obtain a resin composition highly balanced particularly in interlayer adhesion strength and appearance of a molded product. Become. [B (μmol / g) + C (μmol
/ G)] / [A (μmol / g) + D (μmol / g)] is less than 1, there is a possibility that the interlayer adhesion strength is reduced, and if it is more than 15, coloring is remarkable and the appearance of the molded product is deteriorated. There is a fear. [B (μmol / g) + C (μmol / g)] / [A
(Μmol / g) + D (μmol / g)] is more preferably 10, more preferably 7, and most preferably 5
It is.

Also, the EVOH resin composition of the present invention includes:
It is also preferable to add 0.005 to 1 part by weight of a lubricant to 100 parts by weight of EVOH. By adding a lubricant, not only the amount of die attached can be reduced, but also a resin composition made of EVOH which is hardly colored at the time of recovery and has a good long-run property can be obtained. Since the resin composition of the present invention contains a boron compound (E), the effect of suppressing fluctuations in the frequency of occurrence of gels and bumps may be slightly reduced when continuous melt molding is performed for an extremely long time. . However, as a result of a detailed study performed by the present inventors, surprisingly, the EVOH resin composition comprising
It has been found that by adding 0.005 to 1 part by weight of a lubricant to 100 parts by weight, the effect of suppressing fluctuations in the frequency of occurrence of gel and butter can be maintained for an extremely long time.

The preferred content of the lubricant is 0.005 to 1 part by weight of the lubricant based on 100 parts by weight of the EVOH. If the content of the lubricant is less than 0.005 parts by weight with respect to 100 parts by weight of EVOH, the effect of adding the lubricant as described above may be insufficient, and if it exceeds 1 part by weight, surging is likely to occur and the extrusion is stable. May deteriorate. The lower limit of the lubricant content is more preferably 0.01 part by weight or more based on 100 parts by weight of EVOH. The upper limit of the lubricant content is more preferably 0.8 to 100 parts by weight of EVOH.
Not more than 0.7 parts by weight, and most preferably not more than 0.5 parts by weight.

The lubricant which can be used in the present invention is not particularly limited. For example, higher fatty acid amides, higher fatty acid metal salts (for example, calcium stearate), low molecular weight polyolefins (for example, low molecular weight polyethylene having a molecular weight of about 500 to 10,000, or Low-molecular-weight polypropylene and the like), but are not limited thereto. Among them, it is preferable to use higher fatty acid amides. Specifically, higher saturated fatty acid amides (eg, stearic acid amide, palmitic acid amide, lauric acid amide, etc.),
Examples include higher unsaturated fatty acid amides (eg, oleic acid amide, erucic acid amide, etc.), higher bis fatty acid amides (eg, ethylene bisstearic acid amide, methylene bisstearic acid amide, etc.). Here, the higher fatty acid means a fatty acid having 6 or more carbon atoms, and more preferably has 10 or more carbon atoms.

The form of the lubricant may be any of powder, solution, dispersion and the like, and is not particularly limited. Also, the content of the lubricant is not particularly limited, and a method of melt-mixing the resin composition and the lubricant, a method of extruding the solution after the saponification reaction to which the lubricant is added into a coagulating liquid in a strand form, a method of combining these methods Etc.

The resin composition pellets of the present invention also comprise pellets comprising the resin composition of the present invention, wherein the outer surface of the resin composition pellets comprises 0.005 to 0.5 parts by weight of a lubricant per 100 parts by weight of the resin composition. Is suitable as an embodiment of the present invention. The lower limit of the amount of the lubricant attached to the pellets is more preferably at least 0.01 part by weight based on 100 parts by weight of EVOH. The upper limit of the amount of the lubricant attached to the pellet is more preferably EVOH10.
0.3 parts by weight or less, more preferably 0.2 parts by weight or less, and most preferably 0.1 part by weight or less with respect to 0 parts by weight. The amount of the lubricant adhering to the outer surface of the pellets made of the resin composition was 0.1 to 100 parts by weight of the resin composition.
If the amount exceeds 5 parts by weight, the feeding of the pellets to the extruder may not be stable. The method for producing such resin composition pellets is not particularly limited, but a method of dry blending the EVOH resin composition pellets with a lubricant is exemplified as a suitable method.

Suitable melt flow rate (MFR) of the resin composition comprising EVOH obtained in the present invention (190)
° C, measured under a load of 2160 g; melting point is 190 ° C
Those near or exceeding 190 ° C are measured at a plurality of temperatures above the melting point under a load of 2160 g, and the reciprocal of the absolute temperature is plotted as abscissa and the melt flow rate is plotted as ordinate (logarithm) on a semilogarithmic graph. The extrapolated value) is preferably 0.1 to 200 g / 10 min. It is. The lower limit of the MFR is more preferably 0.2 g / 10 min. And more preferably 0.5 g / 10 min. This is optimally 1 g / 10 min. That is all. Also, M
The upper limit of FR is more preferably 50 g / 10 min. Or less, more preferably 10 g / 10 min. Is the following,
Optimally, 7 g / 10 min. It is as follows. When the melt flow rate is smaller than the above range, the inside of the extruder is in a high torque state during molding and extrusion processing becomes difficult. Absent.

It is also possible to blend the resin composition of the present invention with an ethylene-vinyl alcohol copolymer having a different degree of polymerization, ethylene content and saponification degree within a range not to impair the object of the present invention, and melt-mold it. It is. In addition, within the range not impairing the object of the present invention, other various plasticizers, stabilizers, surfactants, coloring agents, ultraviolet absorbers, slip agents, antistatic agents, drying agents, crosslinking agents, etc. It is also possible to add appropriate amounts of metal salts, fillers, reinforcing agents such as various fibers, and the like.

It is also possible to mix an appropriate amount of a thermoplastic resin other than the resin composition as long as the object of the present invention is not impaired. As the thermoplastic resin, various polyolefins (polyethylene, polypropylene, poly 1-butene, poly 4-methyl-1-pentene, ethylene-propylene copolymer, copolymer of ethylene and α-olefin having 4 or more carbon atoms, polyolefin Copolymer of ethylene and maleic anhydride, ethylene-vinyl ester copolymer, ethylene-acrylate ester copolymer, or modified polyolefin obtained by graft-modifying these with unsaturated carboxylic acid or a derivative thereof), various nylons (nylons) -6, nylon-6,6, nylon-6 / 6,6 copolymer), polyvinyl chloride, polyvinylidene chloride, polyester, polystyrene, polyacrylonitrile, polyurethane, polyacetal, and modified polyvinyl alcohol resin.

A carboxylic acid (A) having a molecular weight of less than 75, an alkali metal salt (B), an alkaline earth metal salt (C), a phosphoric acid compound (D) and a boron compound (E) having a molecular weight of less than 75 are added to the ethylene-vinyl alcohol copolymer. The method of containing is not particularly limited. For example, there are a method of immersing the EVOH in a solution in which the compound is dissolved, a method of melting the EVOH and mixing the compound, and a method of dissolving the EVOH in an appropriate solvent and mixing the compound. .

Among them, a method of immersing EVOH in a solution of the above compound is desirable in order to exert the effects of the present invention more remarkably. This processing can be performed by either a batch method or a continuous method. At this time, the shape of the EVOH may be any shape such as powder, granule, sphere, and columnar pellet.

EVOH is converted to a carboxylic acid (A) having a molecular weight of less than 75, an alkali metal salt (B), an alkaline earth metal salt (C), a phosphoric acid compound (D) and a boron compound (E).
When immersed in a solution containing a carboxylic acid (A) having a molecular weight of less than 75, an alkali metal salt (B), an alkaline earth metal salt (C), a phosphoric acid compound (D), and a boron compound (E) in the solution, Is not particularly limited. The solvent of the solution is not particularly limited, but is preferably an aqueous solution for reasons such as handling. The preferred range of immersion time varies depending on the form of EVOH,
In the case of pellets of about 1 to 10 mm, the time is preferably 1 hour or more, preferably 2 hours or more.

In the immersion treatment of the above-mentioned various compounds in a solution, the immersion may be performed by dividing into a plurality of solutions, or may be performed at once. Among them, carboxylic acids (A) having a molecular weight of less than 75, alkali metal salts (B), alkaline earth metal salts (C), phosphoric acid compounds (D) and boron compounds (E)
Is preferred from the viewpoint of simplification of the process. When the treatment is performed by immersion in the solution as described above, drying is finally performed to obtain a target EVOH composition.

The obtained resin composition of the present invention is formed into various molded articles such as films, sheets, containers, pipes and fibers by melt molding. These molded products can be crushed and molded again for the purpose of reuse. It is also possible to uniaxially or biaxially stretch films, sheets, fibers and the like. Examples of the melt molding method include extrusion molding, inflation extrusion, blow molding, melt spinning, and injection molding. The melting temperature varies depending on the melting point of the copolymer, etc.
About 50-270 degreeC is preferable.

As described above, the resin composition of the present invention has at least one layer of a molded product such as a film or sheet of the composition of the present invention, in addition to the production of a resin molded product having only the resin composition as a single layer. It is often used practically as a multilayer structure. When the resin composition of the present invention is represented by E, the adhesive resin is represented by Ad, and the thermoplastic resin is represented by T, E / Ad / T, T / Ad / E / Ad / T, etc. But not limited thereto. Each layer may be a single layer or may be a multilayer in some cases.

The method for producing the above-mentioned multilayer structure is not particularly limited. For example, a method of melt-extruding a thermoplastic resin into a molded product (film, sheet, etc.) comprising the resin composition of the present invention, a method of co-extruding the resin composition of the present invention with another thermoplastic resin, a thermoplastic resin And a method of co-injecting a resin composition comprising EVOH and a molded product obtained from the resin composition comprising EVOH of the present invention and a film or sheet of another base material with an organic titanium compound, an isocyanate compound or a polyester-based resin. Examples include a method of laminating using a known adhesive such as a compound, and among others, a method of co-extrusion with another thermoplastic resin is preferably used.

As the thermoplastic resin used, linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, polypropylene, propylene-α -Olefin copolymer (carbon number 4
Α-olefins), polybutene, polypentene and other olefins alone or copolymers thereof, polyesters such as polyethylene terephthalate, polyester elastomers, polyamide resins such as nylon-6, nylon-6,6, polystyrene, polyvinyl chloride , Polyvinylidene chloride, acrylic resin, vinyl ester resin, polyurethane elastomer, polycarbonate, chlorinated polyethylene, chlorinated polypropylene and the like.
Among them, polypropylene, polyethylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, polyamide, polystyrene, and polyester are preferably used.

In laminating the resin composition of the present invention and a thermoplastic resin, an adhesive resin may be used in some cases. In this case, an adhesive resin composed of a carboxylic acid-modified polyolefin is preferable. Here, the carboxylic acid-modified polyolefin is a modified olefin-based polyolefin containing a carboxyl group obtained by chemically (eg, by addition reaction or graft reaction) bonding an ethylenically unsaturated carboxylic acid or its anhydride to an olefin polymer. Refers to merging. The term "olefin polymer" as used herein means polyethylene (low pressure, medium pressure, high pressure), linear low density polyethylene, polyolefin such as polypropylene, boribene, and comonomers (vinyl ester, non-polyester) capable of copolymerizing olefin with the olefin. (E.g., a saturated carboxylic acid ester), such as an ethylene-vinyl acetate copolymer and an ethylene-ethyl acrylate copolymer. Among them, linear low-density polyethylene, ethylene-vinyl acetate copolymer (vinyl acetate content 5 to 5)
55% by weight), ethylene-ethyl acrylate copolymer (content of ethyl acrylate 8 to 35% by weight) is preferred, and linear low-density polyethylene and ethylene-vinyl acetate copolymer are particularly preferred. It is. Ethylenically unsaturated carboxylic acids or anhydrides include ethylenically unsaturated monocarboxylic acids, esters thereof, ethylenically unsaturated dicarboxylic acids, mono or diesters thereof, and anhydrides thereof, and among them, ethylenically unsaturated dicarboxylic acids Anhydrides are preferred. Specific examples include maleic acid, fumaric acid, itaconic acid, maleic anhydride, itaconic anhydride, monomethyl maleate, monoethyl maleate, diethyl maleate, monomethyl fumarate, among others, maleic anhydride Acids are preferred.

The amount of addition or grafting (degree of modification) of the ethylenically unsaturated carboxylic acid or its anhydride to the olefin polymer is from 0.0001 to 0.01% based on the olefin polymer.
It is 15% by weight, preferably 0.001 to 10% by weight. The addition reaction and graft reaction of the ethylenically unsaturated carboxylic acid or its anhydride to the olefin polymer can be obtained by, for example, a radical polymerization method in the presence of a solvent (such as xylene) and a catalyst (such as peroxide). 190 ° C. of the carboxylic acid-modified polyolefin thus obtained
The melt flow rate (MFR) measured at 0.2 to 3
It is preferably 0 g / 10 min, more preferably 0.5 to 10 g / 10 min. These adhesive resins may be used alone or as a mixture of two or more layers.

The method of coextrusion of the resin composition of the present invention with a thermoplastic resin is not particularly limited, and may be any of a multi-manifold merging T-die method, a feedblock merging T-die method, and an inflation method.

By subjecting the co-extruded multilayer structure thus obtained to secondary processing, various molded products (films, sheets, tubes, bottles, etc.) can be obtained. Can be (1) Multi-layer co-stretched sheet or film by uniaxially or biaxially stretching or biaxially stretching or heat-treating a multi-layered structure (sheet or film) (2) Multi-layered structure (sheet or film) (3) Multi-layered structure (sheet or film, etc.) Multi-layer tray cup-shaped container formed by vacuum forming, air-pressure forming, vacuum-pressure forming, etc. (4) Multi-layered structure Bottles and cup-shaped containers obtained by stretch blow molding from pipes (such as pipes). Such secondary processing methods are not particularly limited, and known secondary processing methods (such as blow molding) other than those described above can also be employed.

The multilayer structure thus obtained is excellent in low odor, has few fish eyes, is transparent, and has few streaks. Therefore, the material for food containers, such as deep drawn containers, cup-shaped containers, bottles, etc. It is suitably used as a material.

[0063]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Hereinafter, “%” and “parts” are based on weight unless otherwise specified. In addition, all the water used ion-exchange water.

(1) Carboxylic acid (A) having a molecular weight of less than 75
Determination of 20 g of dry pellets as a sample with 100 m of deionized water
and extracted by heating at 95 ° C. for 6 hours. The extract was prepared by using phenolphthalein as an indicator and using 1/50 N
The content of the carboxylic acid (A) having a molecular weight of less than 75 was determined by neutralization titration with aOH.

(2) Determination of alkali metal salt (B) and alkaline earth metal salt (C) (Na ion, K ion, M
(Quantitative determination of g ion and Ca ion) 10 g of a dry pellet as a sample was put into 50 ml of a 0.01 N hydrochloric acid aqueous solution, and stirred at 95 ° C for 6 hours. The aqueous solution after stirring was quantitatively analyzed using ion chromatography, and the amounts of Na ion, K ion, Mg ion and Ca ion were quantified. The column is made of Yokogawa Electric's I
The eluent was an aqueous solution containing 5.0 mM tartaric acid and 1.0 mM 2,6-pyridinedicarboxylic acid using CS-C25. In the determination, a calibration curve prepared with an aqueous solution of sodium chloride, an aqueous solution of potassium chloride, an aqueous solution of magnesium chloride, and an aqueous solution of calcium chloride was used. From the amounts of the Na ion, K ion, Mg ion and Ca ion thus obtained, the amounts of the alkali metal salt (B) and the alkaline earth metal salt (C) in the dried pellet were obtained in terms of the metal element. .

(3) Quantification of Phosphate Compound (D) (Quantification of Phosphate Ions) 10 g of a dry pellet as a sample was put into 50 ml of a 0.01 N hydrochloric acid aqueous solution, and stirred at 95 ° C. for 6 hours. The aqueous solution after stirring was quantitatively analyzed using ion chromatography to determine the amount of phosphate ions. Column, Inc.
Use ICS-A23 manufactured by Yokogawa Electric Corp.
An aqueous solution containing mM mM sodium carbonate and 1.0 mM sodium hydrogen carbonate was used. In the determination, a calibration curve prepared with an aqueous solution of sodium dihydrogen phosphate was used. From the amount of phosphate ions thus obtained, the content of the phosphate compound (D) was obtained in terms of phosphate groups.

(4) Determination of Content of Boron Compound (E) 100 g of dry pellets as a sample were put in a magnetic crucible,
Ashed in an electric furnace. The obtained ash was dissolved in 200 mL of a 0.01 N aqueous nitric acid solution and quantified by atomic absorption spectrometry, and the content of boron compound (E) was obtained in terms of boron.

(5) Relationship between Heating Time and MFR 3 to 4 g of dried pellets as a sample were placed in a nitrogen atmosphere in a stainless steel pipe (inner diameter 2.2 cm, length 12.5 cm,
Placed in the internal volume 50 cm ^3), after the inside of the stainless steel pipe was thoroughly replaced by nitrogen gas, it was carried out heat treatment at 220 ° C.. After the heat treatment, the MFR of the resin was measured using a melt indexer @ Melt Indexer L manufactured by Takara Kogyo Co., Ltd.
203 (pore diameter of cylinder to put sample: 9.48m
m, piston diameter φ9.48mm, die diameter φ2.09
mm, die length 8.01 mm)
After heating at 6 ° C. for 6 minutes, a load was applied at 10.9 kg and measurement was performed.

(6) Heating Melt Coloring Test 8 g of the dried pellets as samples were sandwiched between hot plates heated at 230 ° C. (Sindoh tabletop test press YS-5), and the gap between the hot plates was maintained at 5 mm. After heating for one minute, the degree of coloring was visually determined and determined as follows. A: No coloring B: Slightly yellowing C: Yellowing D: Intense coloring

(7) Single-Layer Film Forming Test A single-layer film was prepared by the following method, and the appearance, die adhesion amount, and long-run property of the molded product were evaluated. Model Single screw extruder (non-vented type) L / D 20 Caliber 20mmφ Screw Single full flight type, Surface nitrided steel Screw rotation speed 40rpm Dice 300mm width Coat hanger die Lip gap 0.3mm Cylinder, die temperature setting C1 / C2 / C3 / Die = 195/230/230/2
20 (° C)

(7-a) Variation in the number of gel-like spots and the frequency of occurrence of gel-like spots The above-mentioned film formation was carried out continuously for 8 days, and the film was sampled every hour to obtain gel-like spots (confirmed with the naked eye). About 15
(0 μm or more) was counted and converted to around 1.0 m ² , and the average value of the number of gel-like bumps per day was obtained from the obtained data. In addition, during the film forming test, the condition of streaks and gel-like spots is continuously visually observed, and the number of times per day that streaks and gel-like spots increase suddenly (100 pieces / m ² or more) is measured. did. (7-b) Amount of Die Attachment After a single-layer film formation of EVOH was performed for 8 hours using the sample resin composition, the EVOH resin in the extruder was replaced with LDPE (low density polyethylene) with MFR = 1 for 1 hour. Thereafter, the weight of the EVOH thermally degraded resin attached inside the die was measured. It was determined as follows based on the weight. A: less than 1.5 g B: 1.5 to 5 g C: 5 to 10 g
D: 10g or more

(8) Interlaminar Adhesive Strength The T-peel strength between the ethylene-vinyl alcohol copolymer / adhesive resin immediately after the formation of a three-layer five-layer film obtained by the following coextrusion molding was measured at 20 ° C.-65. % RH conditions,
The measurement was performed using an autograph (tensile speed: 250 mm / min). The value was determined as follows based on the peel strength. A: 500 g / 15 mm or more B: 300 to 500 g /
Less than 15 mm C; less than 300 g / 15 mm (co-pressing condition) Layer composition: LLDPE / adhesive resin / EVOH resin composition / adhesive resin / LLDPE (thickness 50/10/10/1)
0/50: unit is μm) LLDPE: ULTOZEX 3523L manufactured by Mitsui Chemicals Adhesive resin: Bondyne TX803 manufactured by Sumitomo Chemical Industries
0 Extrusion temperature of each resin: C1 / C2 / C3 / die = 170 /
170/220/220 ° C Extruder for each resin, T-die specification: LLDPE; 32φ extruder GT-32-A type (manufactured by Plastic Engineering Laboratory) Adhesive resin; 25φ extruder P25-18AC (manufactured by Osaka Seiki) EVOH ; 20φ extruder Laboratory machine ME type CO-EXT
(Made by Toyo Seiki Co., Ltd.) T-die; for 300mm width 3 types 5 layers (made by Plastics Engineering Laboratory) Cooling roll temperature: 50 ° C Picking speed: 4m / min

(9) Recoverability The formed EVOH single-layer film (film-formed product up to 2 hours after the start of film formation) is pulverized, melted, and pelletized again (pelletization temperature: 220 ° C.). Single-layer film formation was performed again using the pellets. (9-a) Coloring resistance The film was wound around a paper tube, and the degree of coloring on the end face of the film was determined with the naked eye and determined as follows. A: No coloring B: Slightly yellowing C: Yellowing D: Intense coloring (9-b) Generation of bumps Gel-like bumps of the film after one hour of monolayer film formation (approximately 150 μm or more that can be visually confirmed) ) And 1.
It was converted to around 0 m ² . Judgment was made as follows based on the number of spots. A: less than 20 B: 20 to 40 C: 40 to 60 D: 60 or more

(10) Intrinsic Viscosity 0.20 g of a sample pellet of a resin composition composed of EVOH
Is weighed accurately, and this is hydrated phenol (water / phenol = 1).
(5/85 wt%), heated and dissolved in 40 ml at 60 ° C. for 3 to 4 hours, and measured at 30 ° C. with an Ostwald viscometer (t0 = 90 seconds). ]. [Η] = (2 × (ηsp−lnηrel)) ^1/2 / C (l /
g) ηsp = t / t0-1 (specific viscosity) ηrel = t / t0 (relative viscosity) C; EVOH concentration (g / l) ・ t0: Time when blank (hydrous phenol) passes through viscometer ・ t: sample Time when the aqueous phenol solution in which is dissolved is passed through the viscometer

Example 1 A saponification reactor was charged with a 45% methanol solution of an ethylene-vinyl acetate copolymer having an ethylene content of 38 mol%.
Caustic soda / methanol solution (80 g / L) was added so as to be 0.4 equivalent to the vinyl acetate component in the copolymer, and methanol was added to adjust the copolymer concentration to 20%. . The temperature was raised to 60 ° C., and the reaction was carried out for about 4 hours while blowing nitrogen gas into the reactor. Four hours later, the reaction was stopped by neutralization with acetic acid, and the mixture was extruded into water from a metal plate having a circular opening to be precipitated, and cut to a diameter of about 3 mm.
A pellet having a length of about 5 mm was obtained. The operation of removing the obtained pellet by a centrifugal separator, adding a large amount of water, and removing the liquid was repeated.

100 parts by weight of water-containing pellets (ethylene content 38 mol%, saponification degree 99.4%, water content 55% by weight) of the ethylene-vinyl alcohol copolymer thus obtained were added to 0.32 g of boric acid. L, sodium acetate 0.4
g / L, 0.24 g / L of magnesium acetate, 0.17 g / L of potassium dihydrogen phosphate, and 370 parts by weight of an aqueous solution containing 0.5 g / L of acetic acid were immersed at 25 ° C. for 6 hours. After immersion, the solution was drained, and then at 80 ° C. for 3 hours, and subsequently at 107 ° C. for 24 hours.
Drying was performed using a hot air dryer for hours to obtain dried pellets. 100 parts by weight of the dried pellets were added to a lubricant Alflow H.
0.02 parts by weight of -50T (manufactured by NOF CORPORATION; ethylene bisstearic acid amide) was dry-blended and mixed well to obtain an EVOH resin composition pellet.

The content of the carboxylic acid (A) having a molecular weight of less than 75 in the obtained dried pellets is 250 ppm, the content of the alkali metal salt (B) is 220 ppm in terms of metal, and the content of the alkaline earth metal salt (C) is The amount is 35pp in metal conversion
m, the content of the phosphoric acid compound (D) is 10
The content of 0 ppm and the boron compound (E) was 240 ppm in terms of boron. Further, the MFR (measured at 190 ° C. under a load of 2160 g) of the obtained EVOH resin composition pellet was 2.0 g / 10 min.

Using the obtained EVOH resin composition pellets, the relationship between the heating time and the MFR was examined according to the method described above (see FIG. 1), and a heat-melting coloring test was performed. MFRma
x / MFRO was 1.6, and the result of the heat-melt coloring test was A. In addition, the above-mentioned resin composition showed a minimum value within 10 hours from the start of heating, and a maximum value (MFRmax) within 100 hours after the minimum value was shown.

Using the obtained EVOH resin composition pellets, a single-layer film-forming test was carried out according to the above-mentioned method, and the number of gel-like spots generated, the change in the frequency of gel-like spots, and the amount of die attached were examined. The occurrence of gel-like spots was as small as 4 to 5 pieces / m ^{2 on} average for 8 days, no sudden increase in streaks or gel-like spots was observed, and a molded article having a good appearance was obtained. It showed a long run. Further, the test result of the die adhesion amount was also judged as A.

Using the obtained EVOH resin composition pellets, the interlayer adhesion was measured by the method described above. The T-type peel strength between the resin composition / adhesive resin composed of EVOH immediately after film formation was determined to be A.

Using the film obtained in the single-layer film-forming test (film-formed product up to 2 hours after the start of film-forming), recoverability ((a) coloring resistance and (b) spot generation) by the above method. Was tested. In the test results, the recoverability was determined to be A in any of the evaluation items of (a) the color resistance and (b) the occurrence of spots.

Examples 2 to 6 and Comparative Examples 1 to 8 Using EVOH having an intrinsic viscosity shown in Table 2, an ethylene content of 38 mol% after saponification, washing and dewatering, and a saponification degree of 99.4% A dry pellet was prepared in the same manner as in Example 1 except that the composition of the solution for immersing EVOH was changed as shown in Table 1, and the presence or absence of a lubricant was added.
A film was prepared. Table 2 shows the composition of the pellets used in each Example and Comparative Example, and Table 3 shows the evaluation results of various tests.

The resin compositions of Examples 2 to 6, Comparative Examples 1 and 2, and Comparative Examples 4 to 8 exhibited a minimum value within 10 hours from the start of heating and within 100 hours after the minimum value was exhibited. Shows the maximum value (MFRmax). However, in the resin composition of Comparative Example 4, the MFR did not show a minimum value or a maximum value.

[0084]

[Table 1]

[0085]

[Table 2]

[0086]

[Table 3]

EV of Embodiments 1 to 6 Having Configuration of the Present Invention
The resin composition composed of OH is excellent in appearance with little coloring, fish eyes (gels / buds), streaks, etc., excellent in long-run property in melt molding, less coloring in collection, and in the laminate. When it did, it was excellent in interlayer adhesiveness. In Example 6, which did not contain a lubricant, the effect of improving the color resistance and the effect of reducing the amount of die attached were slightly reduced as compared with Example 1, and the effect of suppressing gel / bubbles and the occurrence of gel-like bumps Although the effect of suppressing the frequency of a rapid increase in the number was somewhat reduced, it was practical.

However, in Comparative Example 1 containing no boron compound (E), the effect of suppressing the generation of gel and butter was insufficient, and in Comparative Example 2 containing no phosphoric acid compound (D), the colorfastness at the time of film recovery was not improved. The properties were unsatisfactory.

Further, the resin composition was heated at 220 ° C. in a nitrogen atmosphere.
Time and MFR at 230 ° C (10.9kg load)
In Comparative Example 3 having no configuration of the present invention in which the MFR shows a local minimum value within 10 hours from the start of heating, and shows a local maximum value (MFRmax) within 100 hours after showing the local minimum value, The effect of reducing the amount of die attached was not obtained, and the frequency of occurrence of gels and butters increased rapidly several times a day, resulting in poor productivity.

In Comparative Example 4 in which MFRmax / MFRO exceeds 45 and in Comparative Example 5 in which the content of the carboxylic acid (A) having a molecular weight of less than 75 is less than 50 ppm, sufficient coloring resistance was not obtained. Further, when the alkali metal salt (B) is 50
In Comparative Example 6 less than ppm, sufficient adhesiveness could not be obtained.

In Comparative Example 7 of the present application having the same configuration as that of Comparative Example 7 of Japanese Patent Application Laid-Open No. H10-67898,
Since MFRmax / MFR0 exceeds 45, the color resistance is poor, and the content of the boron compound (E) is 50 ppm.
Therefore, the number of gel spots increased as the operation was continued for a long time. In Comparative Example 8 in which the content of the carboxylic acid (A) having a molecular weight of less than 75 exceeds 500 ppm,
The adhesiveness was poor, and the effect of suppressing the generation of gel and butter was unsatisfactory.

[0092]

EFFECT OF THE INVENTION Coloring, fish eye (gel / buts),
Resin composition composed of ethylene-vinyl alcohol copolymer with few streaks, etc., excellent appearance, excellent long-run property during melt molding, little coloring during recovery, and excellent interlayer adhesion when formed into a laminate And a multilayer structure using the same.

[Brief description of the drawings]

FIG. 1 shows the heating time of a resin composition composed of EVOH at 220 ° C. in a nitrogen atmosphere and the MFR (230 ° C., 10.9 k
FIG. 4 is a diagram showing a relationship of (g load).

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C08K 3/38 C08K 3/38 5/09 5/09 C08L 29/04 C08L 29/04 A // B29K 29 : 00 B29K 29:00 (72) Inventor Naoyuki Himi 1-2-1, Kaigandori, Okayama City, Okayama Prefecture Kuraray Co., Ltd.

Claims (6)

[Claims] 1. A resin composition comprising an ethylene-vinyl alcohol copolymer, wherein the MFR of the resin composition is increased when the resin composition is heated at 220 ° C. under a nitrogen atmosphere.
(230 ° C., 10.9 kg load) shows a local minimum value within 10 hours from the start of heating, and shows a local maximum value (MFRmax) within 100 hours after showing the local minimum value,
Carboxylic acid (A) having a molecular weight of less than 75 is converted into 50 to 500 pp
m, the alkali metal salt (B) is 50 to 50 in terms of a metal element.
0 ppm, 10 to 120 ppm of an alkaline earth metal salt (C) in terms of a metal element, 10 to 200 ppm of a phosphate compound (D) in terms of a phosphate group, 50 to 2000 ppm of a boron compound (E) in terms of a boron element, and A resin composition satisfying the following formula (1). 0.5 ≦ MFRmax / MFR0 ≦ 45 (1) where, MFRmax: MFR of the resin composition when the resin composition is heated at 220 ° C. under a nitrogen atmosphere (230 ° C., 1
Maximum value of 0.9 kg load) MFR0: MF of resin composition not subjected to heat treatment
R (230 ° C, 10.9kg load) 2. The resin composition according to claim 1, wherein the carboxylic acid (A) having a molecular weight of less than 75 is acetic acid. 3. The resin composition according to claim 1, wherein the following formula (2) is satisfied. 1 ≦ [B (μmol / g) + C (μmol / g)] / [D (μmol / g) + A (μmol / g)] ≦ 15 (2) where A: molecular weight of 75 per unit weight of resin composition B: content of carboxylic acid (a2) less than (μmol / g) B: content of alkali metal salt (B) per unit weight of resin composition (in terms of metal element: μmol / g) 0C: unit of resin composition Content of alkaline earth metal salt (C) per weight (in terms of metal element: μmol / g) D: Phosphoric acid compound (D) per unit weight of resin composition
Content (in terms of phosphate radical: μmol / g) 4. An ethylene-vinyl alcohol copolymer 1.
The resin composition according to any one of claims 1 to 3, comprising 0.005 to 1 part by weight of a lubricant based on 00 parts by weight. 5. A lubricant comprising 0.005 to 0.5 parts by weight of a lubricant, based on 100 parts by weight of the resin composition, on the outer surface of a pellet comprising the resin composition according to claim 1. Resin composition pellets. 6. A multilayer structure comprising a layer made of the resin composition according to claim 1 and a thermoplastic resin laminated on at least one surface of the layer.