JP2001072823A - Resin composition comprising ethylene-vinyl alcohol copolymer and multilayer structure using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject resin composition having greatly high adhesivity, slightly generating gels/granular matters therein, excellent in long-run property, good in recoverability and slight in coloration when recovered, and to obtain a multilayer structure using the composition. SOLUTION: This resin composition comprises an ethylene-vinyl alcohol copolymer and contains (A) 10-500 ppm of acetic acid, (B) 500-2,000 ppm, calculated as metallic element, of an alkali metal salt and (C) 10-500 ppm, calculated as phosphate ion, of a phosphoric acid compound, and also preferably (D) 20-2,000 ppm, calculated as boron element, of a boron compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to an ethylene-vinyl alcohol copolymer having excellent adhesiveness, low appearance of gels and bumps, excellent appearance, good long-run property and good recoverability, and little coloration during recovery. The present invention relates to a resin composition comprising a united product and a multilayer structure 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. It is molded into sheets, containers, etc., and is widely used as various packaging materials. Since such molding is usually carried out by melt molding, EVOH has a long run property at the time of melt molding (a molded article free of fish eyes and streaks is obtained even for a long period of time), and an appearance (the generation of gels and bumps). Which are not seen). In recent years, recyclability has also become an important issue, and even when an EVOH molded product is collected and melt-molded again to repeat the heat history, the recoverability (the moldability of the collected EVOH) is good. EVO with little coloring at the time of recovery
H is required.

[0003] Also, in order to impart mechanical strength, moisture resistance, heat sealability and the like to an EVOH molded product, it is generally co-extruded with a base material such as a polyolefin resin through an adhesive layer to form a multilayer structure. Therefore, EVOH is required to have high interlayer adhesion. To improve the interlayer adhesion, (1) a method of adding a trace component, particularly an alkali metal, to EVOH is known. In order to improve the appearance represented by the above-mentioned long-run properties and gel buttes, (2) a metal salt of Group II of the periodic table is added in an amount of 0.0005 to 0.0005.
0.05% by weight (in terms of metal element), 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 0.1% of an acid having a pKa of 3.5 or more and a boiling point of 120 ° C. or less.
An EVOH composition containing from 0.1 to 0.2% by weight and exhibiting specific flow characteristics has been disclosed (JP-A-64-66).
262). Further, as another prior art, as an EVOH having excellent long-run property, appearance and interlayer adhesion during melt molding, (3) 0.001 to 1 part by weight of a boron compound (D) with respect to 100 parts by weight of EVOH ( Boron element), acetic acid 0.05 parts by weight or less, and acetate 0.
A resin composition containing 001 to 0.05 parts by weight (in terms of metal element) is disclosed (JP-A-11-4357).
No. 1). Further, as the comparative example 5, the publication discloses EV
There is disclosed a resin composition containing 0.03 parts by weight of boric acid (in terms of boron element), 0.009 parts by weight of acetic acid, and 0.08 parts by weight of sodium acetate (in terms of sodium) based on 100 parts by weight of OH. However, although a film formed by molding such a resin composition has excellent interlayer adhesion, there are problems in appearance due to frequent occurrence of streaks and fish eyes,
In addition, it describes that there is much stretching unevenness.

[0004]

However, the disclosed technologies (1) and (2) as described above cannot sufficiently improve the interlayer adhesion of EVOH, and further improvement is required. In addition, adhesive resins for nylon, which have a low ability to adhere to EVOH, are EVOH.
Could not be used for the multilayer structure of the above. for that reason,
In order to laminate EVOH on a base material such as a polyolefin-based resin, it is necessary to use a high-performance and high-price adhesive resin dedicated to EVOH, and the range of adhesive resin options is small.

[0005] Further, in the disclosed technique (3) as described above, EVOH has high interlayer adhesion, but problems remain in appearance, stretching unevenness, and the like. As described above, it is extremely difficult to achieve both high interlayer adhesion and appearance of a molded product, and it has been strongly desired to develop a resin composition composed of EVOH that satisfies such requirements. Further, from the viewpoint of long-term operation of the molding machine and reuse of burrs and the like generated at the time of molding, the resin composition is excellent in interlayer adhesion and appearance, long-running property, excellent in recoverability, and coloring during recovery. Less was desired.

[0006]

SUMMARY OF THE INVENTION The above-mentioned object is to provide acetic acid (A) in an amount of 10 to 500 ppm and an alkali metal salt (B).
Is solved by a resin composition comprising an ethylene-vinyl alcohol copolymer containing 500 to 2000 ppm in terms of a metal element and 10 to 500 ppm in terms of a phosphate group of a phosphoric acid compound (C).

That is, according to the present invention, acetic acid (A) is
00 ppm, alkali metal salt (B) is 5
The present invention relates to a resin composition comprising an ethylene-vinyl alcohol copolymer containing 100 to 2000 ppm of a phosphoric acid compound (C) in an amount of 10 to 500 ppm in terms of a phosphate group.

[0008] In a preferred embodiment, the resin composition of the present invention contains the boron compound (D) in an amount of 20 to 2000 ppm.

In a preferred embodiment, the resin composition of the present invention has a content of alkali metal salt (B) (in terms of metal element: p
pm) is 3 to 20 times the content (ppm) of acetic acid (A).

In a preferred embodiment, when the resin composition of the present invention is heated at 220 ° C. in a nitrogen atmosphere,
MFR (2
The maximum value (MFRma measured at 30 ° C-10.9 kg)
x) and the MFR (230
Measured at 10.9 kg. (Definition: MFR0) satisfies the following expression (1). 0.1 <MFRmax / MFR0 <10 (1)

Further, in a preferred embodiment, the resin composition of the present invention is a resin composition for coextrusion molding.

Further, the present invention relates to a multilayer structure including at least one layer made of the above resin composition.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The acetic acid (A) of the present invention is used in an amount of 10 to 50.
0 ppm, an alkali metal salt (B) of 50
A resin composition comprising an ethylene-vinyl alcohol copolymer containing 0 to 2000 ppm and a phosphoric acid compound (C) in an amount of 10 to 500 ppm in terms of a phosphate group has a very high interlayer adhesiveness, so that the adhesive for EVOH is used. Adheres very strongly to conductive resins. For this reason, the resin composition is particularly suitable for coextrusion molding, but is not limited thereto.

The adhesive resin for nylon is EVOH.
It has been considered that there is a problem in the adhesiveness with EVOH, and it has not been possible to use it for a multilayer structure with EVOH. However, the resin composition of the present invention has an excellent interlayer adhesiveness. , Especially a co-extruded multilayer structure. As described above, the present invention is significant from the viewpoint of increasing the choice of usable adhesive resins.

The EVOH used in the present invention is preferably obtained by saponifying an ethylene-vinyl ester copolymer, and among them, the ethylene content is preferably 3 to 70 mol%. From the viewpoint of obtaining a molded article having excellent gas barrier properties and melt moldability, the ethylene content is preferably from 10 to 65 mol%, more preferably from 20 to 6 mol%.
Preferred is 5 mol%, optimally 25-60 mol%. Further, the lower limit of the saponification degree of the vinyl ester component is preferably 80% or more, and from the viewpoint of obtaining a molded article having excellent gas barrier properties, more preferably 95% or more, and further preferably 98% or more. It is particularly preferably at least 99%. 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%, the barrier properties, thermal stability, and moisture resistance may be deteriorated.

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

A typical example of the vinyl ester used in the production of EVOH is vinyl acetate.
Other fatty acid vinyl esters (vinyl propionate,
Vinyl pivalate) can also be used. Also, EVOH
Is a vinyl silane compound as a copolymer component 0.0002 to
0.2 mol% can be contained. Here, as the vinylsilane-based compound, for example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri (β
-Methoxy-ethoxy) silane and 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 ester and ethylene-vinyl ester 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,
Azonitrile initiators such as 2-azobis- (4-methoxy-2,4-dimethylvaleronitrile) and 2,2-azobis- (2-cyclopropylpropionitrile) and isobutyryl peroxide, cumylperoxyneodeca Noate, diisopropyl peroxycarbonate,
Organic peroxide initiators such as di-n-propyl peroxydicarbonate, t-butyl peroxy neodecanoate, lauroyl peroxide, benzoyl peroxide, and t-butyl hydroperoxide 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 10 to 65 mol%, further preferably 20 to 65 mol%, particularly 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 reaches 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 is employed in which mixed vapor is discharged and the copolymer solution from which unreacted vinyl acetate has been removed is taken out from the bottom of the column.

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, the lower limit of the degree of saponification is preferably 80% or more, more preferably 95% or more, still more preferably 98% or more, and particularly preferably 99% or more. That is all. 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 content of acetic acid (A) in the resin composition comprising EVOH of the present invention is from 10 to 500 ppm. When the content of acetic acid (A) is less than 10 ppm, coloring at the time of melting is remarkable. If it exceeds 500 ppm, the effect of improving the adhesive strength with the adhesive resin in coextrusion molding will be insufficient. The lower limit of the content of acetic acid (A) is preferably 30 ppm
And more preferably 50 ppm or more. The upper limit of the content of acetic acid (A) is preferably 200 ppm.
Or less, more preferably 150 ppm or less.

The content of the alkali metal salt (B) in the resin composition comprising EVOH of the present invention is 50 in terms of a metal element.
0 to 2000 ppm. Here, it is extremely important that the content of the alkali metal salt (B) exceeds 500 ppm (in terms of a metal element), and by adopting such a configuration, it is possible to impart excellent adhesiveness to EVOH.

When the content of the alkali metal salt (B) is 500 ppm or less, the effect of improving the adhesion becomes unsatisfactory. In particular, in co-extrusion molding, the adhesive strength with a low-performance adhesive resin such as an adhesive resin for nylon is insufficient. Also 200
If it exceeds 0 ppm, 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 lower limit of the content of the alkali metal salt (B) in the resin composition of the present invention is preferably 510 ppm or more, and more preferably 520 ppm.
pm or more, particularly preferably 530 ppm or more. Further, the upper limit of the content of the alkali metal salt (B) is preferably 1500 ppm or less, more preferably 1000 ppm.
The content is particularly preferably 750 ppm or less.

The content of the alkali metal salt (B) in the resin composition comprising EVOH of the present invention (in terms of metal element: pp
It is particularly preferable that m) is 3 to 20 times the content (ppm) of acetic acid (A) as an embodiment of the present invention. Since the resin composition comprising the EVOH of the present invention contains more alkali metal salt than ordinary EVOH, there is a possibility that the coloring of the molded product and the generation of gel / bubbles may become severe, but the content of acetic acid (A) is reduced. By appropriately adjusting the pH of the resin to a certain range, it is possible to effectively suppress the occurrence of coloration and gels and bumps. The content of alkali metal salt (B) (in terms of metal element: ppm) is determined by the content of acetic acid (A) (p
pm), more preferably 4 times or more, and even more preferably 5 times or more. Further, the content (in terms of metal element: ppm) of the alkali metal salt (B) is more preferably 10 times or less, and more preferably 7.5 times or less, the content (ppm) of acetic acid (A). More preferred. If it is less than 3 times, the adhesive strength of the resin composition of the present invention, particularly the adhesive strength with the adhesive resin for nylon (adhesive resin having low adhesiveness to EVOH) may be insufficient, and more than 20 times. In such a case, there is a possibility that coloring at the time of resin melting becomes remarkable.

The content of the phosphate compound (C) in the resin composition comprising EVOH of the present invention is 10 to 5 in terms of phosphate group.
00 ppm. Examples of the phosphoric acid compound (C) include various acids such as phosphoric acid and phosphorous acid, and salts thereof.
It is not limited to these. 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 (C) in the form of sodium dihydrogen phosphate, potassium dihydrogen phosphate, disodium hydrogen phosphate, and dipotassium hydrogen phosphate.

The resin composition comprising the EVOH of the present invention comprises:
Since it contains more alkali metal salt than ordinary EVOH, if the phosphoric acid compound (C) is not appropriately added, coloring of the molded product and generation of gel and butter become severe. The above-mentioned improvement effect by the addition of the phosphoric acid compound (C) is particularly remarkable at the time of long run molding and at the time of collecting the molded product. The lower limit of the content of the phosphate compound (C) is 50 in terms of phosphate groups.
ppm or more, more preferably 70 ppm or more.
ppm or more. Further, the upper limit of the content of the phosphoric acid compound (C) is preferably not more than 300 ppm, more preferably not more than 200 ppm in terms of phosphate groups. By containing the phosphoric acid compound (C) in such a range, it is possible to obtain a resin composition comprising an ethylene-vinyl alcohol copolymer, which is less colored and hardly gels. When the content of the phosphoric acid compound (C) is less than 10 ppm, coloring at the time of melt molding is severe and appearance is reduced.
In particular, when the heat history is repeated, the tendency is remarkable, so that the resin composition has poor recoverability. In addition, when the content of the phosphoric acid compound (C) exceeds 500 ppm, the occurrence of gel and butter in the molded product becomes remarkable, and the appearance is reduced.

It is preferable to add a boron compound (D) to the resin composition comprising EVOH of the present invention from the viewpoint of further improving the long-run property and the melt moldability of the resin composition. When a boron compound (D) is added to a resin composition composed of EVOH, the melt viscosity can be increased even when EVOH having a low degree of polymerization is used. EV
It is possible to suppress the generation of gels and butters more than OH and to improve the long-run property. The reason why the addition of the boron compound (D) improves the melt viscosity of the resin composition composed of EVOH is unknown, but it is probably because the hydroxyl group of EVOH forms a pseudo-crosslink with the boron compound (D). It is. However, as a result of detailed studies by the present inventors, an adhesive resin having a low adhesive ability to EVOH (for example,
With respect to adhesive resin for nylon), it was found that the addition of a boron compound (D) to EVOH reduces the adhesive ability between EVOH and the adhesive resin.

However, the acetic acid (A) of the present invention is used in an amount of 10 to 5%.
00 ppm, alkali metal salt (B) is 5
Very high adhesion is maintained even when a boron compound (D) is added by using a resin composition composed of EVOH containing 100 to 2000 ppm and a phosphate compound (C) of 10 to 500 ppm in terms of a phosphate group. In addition, it has become possible to obtain the effect of improving the long run property and the melt moldability by adding the boron compound (D). The improvement of the adhesion ability is particularly effective in the boron-added system,
From this viewpoint, the significance of the present invention is great.

As the boron compound (D), boric acids,
Examples include, but are not limited to, borate esters, borates, borohydrides, and the like. Specifically, the boric acids include orthoboric acid, metaboric acid, tetraboric acid and the like, and the boric acid esters include triethyl borate,
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 simply referred to as boric acid) is preferred. The content of the boron compound (D) is 20 to 200 in terms of boron element.
0 ppm, preferably 50-1000 ppm
Is more preferable. If the amount is less than 10 ppm, the effect of improving the long-run property by adding the boron compound (D) may not be obtained. If the amount exceeds 20,000 ppm, gelation is likely to occur, resulting in poor moldability.

It is not clear why the addition of the boron compound (D) reduces the adhesive ability, but the alkali metal salt (B)
Is less than 300 ppm in terms of metal element (Comparative Example 3 of the present application), the adhesive ability of the resin composition comprising EVOH of the present invention is significantly reduced. It is considered that the effect of improving the adhesive ability by the addition is suppressed. Therefore, particularly in a system to which the boron compound (D) is added, the content of the alkali metal (B) is particularly preferably 510 ppm or more, more preferably 520 ppm or more, more preferably 530 ppm or more in terms of the metal element. Is particularly preferred.

It is preferable to add an alkaline earth metal salt (E) to the resin composition comprising EVOH of the present invention. When the alkaline earth metal salt (E) is added, the effect of improving the color resistance is slightly reduced, but the amount of the thermally deteriorated resin adhered to the die by the molding machine during melt molding using the resin composition is further increased. It is possible to reduce. The alkaline earth metal salt (E) is not particularly limited, and examples thereof include a magnesium salt, a calcium salt, a barium salt, and a beryllium salt, and a magnesium salt and a calcium salt are particularly preferable. The anionic species of the alkaline earth metal salt (E) is not particularly limited, either, but an acetate anion or a phosphate anion is preferred. The content of the alkaline earth metal is preferably 10 to 200 ppm in terms of a metal element, more preferably 1 to 200 ppm.
0 to 100 ppm. If the content of the alkaline earth metal is less than 10 ppm, the effect of improving the long-run property may be insufficient, and if it exceeds 200 ppm, coloring during resin melting becomes severe.

Suitable melt flow rate (MFR) of the ethylene-vinyl alcohol copolymer obtained in the present invention
(Measured under a load of 190 ° C. and 2160 g; however, those having a melting point of around 190 ° C. or exceeding 190 ° C.
Under a load of g, the temperature was measured at a plurality of temperatures equal to or higher than the melting point. 1 to 200 g / 10 min. , Optimally 0.2-1
00g / 10min. It is.

When the composition comprising the EVOH of the present invention is heat-treated at 220 ° C. in a nitrogen atmosphere, the MFR (230 ° C.
10.9 kg) (measured at 10.9 kg) (defined as MFRmax) and the MFR (230
Measured at 10.9 kg. It is preferable that the relationship of MFR0 satisfies the following expression (1). 0.1 <MFRmax / MFRO <10 (1) The lower limit of MFRmax / MFRO is more preferably 0.5 or more, and further preferably 1 or more.
Further, the upper limit of MFRmax / MFRO is more preferably 8 or less, and further preferably 5 or less. By employing such a configuration, the effect of improving the long-run property of the resin composition of the present invention is further improved. MFRmax /
If MFR0 is less than 0.1, the effect of suppressing the generation of bumps due to gelation of EVOH may be unsatisfactory. Also, M
EVOH when FRmax / MFR0 exceeds 10
Decomposition and subsequent gelation may be promoted, which may cause a problem in long-run property. The heat treatment was performed by putting ³ parts of resin in a stainless steel pipe (2.2 cm inside diameter, 12.5 cm length, 50 cm ³ internal volume).
４4 g, and the inside of the stainless steel pipe was sufficiently replaced with nitrogen gas, and then the test was performed at 220 ° C. Further, the MFR of the resin was measured by heating the resin at 230 ° C. for 6 minutes in a melt indexer and applying a load of 10.9 kg.

Further, an ethylene-vinyl alcohol copolymer having a different degree of polymerization, ethylene content and saponification degree is blended with the resin composition comprising the EVOH of the present invention within a range not to impair the effects of the present invention, and melt-molded. It is also possible. In addition, the resin composition contains various other plasticizers, stabilizers, surfactants, coloring agents, ultraviolet absorbers, slip agents, antistatic agents, drying agents, cross-linking agents, metal salts, fillers, and various fibers. It is also possible to add an appropriate amount of a reinforcing agent or the like.

In addition, as long as the effects of the present invention are not impaired,
It is also possible to mix a suitable amount of a thermoplastic resin other than the resin composition. 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.

Ethylene-vinyl alcohol copolymer (E
VOH) to acetic acid (A), alkali metal salt (B), phosphoric acid compound (C) and, if necessary, boron compound (D);
The method for containing the alkaline earth metal salt (E) is not particularly limited. For example, E is added to a solution in which the above compound is dissolved.
There are a method of immersing VOH, a method of melting EVOH and mixing the compound, and a method of dissolving EVOH in an appropriate solvent and mixing the compound.

Of these, 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 chip.

When EVOH is immersed in a solution containing acetic acid (A), alkali metal salt (B), phosphoric acid compound (C) and, if necessary, boron compound (D) and alkaline earth metal salt (E). Acetic acid (A), alkali metal salt (B), phosphoric acid compound (C), boron compound (D) in the above solution
And the alkaline earth metal salt (E) are not particularly limited. The solvent of the solution is not particularly limited,
It is preferable to use an aqueous solution for reasons such as handling. E
The weight of the solution when immersing the VOH is the EVOH when dry.
It is desirably at least 3 times, preferably at least 20 times the weight of The preferred range of the immersion time varies depending on the form of the ethylene-vinyl alcohol copolymer,
In the case of a chip having a size of about 10 mm to 10 mm, the time is preferably 1 hour or more, preferably 2 hours or more.

The immersion treatment of the above-mentioned various compounds in a solution may be carried out by dividing into a plurality of solutions and immersion at once. Above all, treatment is performed with a solution containing all of acetic acid (A), alkali metal salt (B), phosphate compound (C) (and, if necessary, boron compound (D) and alkaline earth metal salt (E)). Is preferable from the viewpoint of simplification of the process. When immersed in the solution as described above,
Finally, drying is performed to obtain the desired ethylene-vinyl alcohol copolymer composition.

The obtained resin composition comprising EVOH of the present invention is formed into various molded articles such as films, sheets, containers, pipes, fibers and the like 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 and the like, but is preferably about 150 to 270 ° C.

The resin composition comprising the EVOH of the present invention comprises:
As described above, in addition to the production of a resin molded product having only the resin composition as a single layer, the composition film of the present invention can be put to practical use as a multilayer structure having at least one molded product such as a sheet. Many. As a layer configuration of the multilayer structure,
When the resin composition comprising the EVOH 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,
Examples include, but are not limited to, T / Ad / E / Ad / T. 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. The resin composition comprising the EVOH of the present invention is very excellent in interlayer adhesion, and thus is suitable for a resin composition for coextrusion molding and a coextruded multilayer structure using the same.

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.

When laminating the resin composition comprising EVOH of the present invention and a thermoplastic resin, an adhesive resin may be used. In this case, an adhesive resin composed of a carboxylic acid-modified polyolefin is used as the adhesive resin. preferable. The carboxylic acid-modified polyolefin is a modified olefin polymer containing a carboxyl group obtained by chemically (eg, by addition reaction or graft reaction) bonding an ethylenically unsaturated carboxylic acid or an anhydride thereof to an olefin polymer. It is suitable. Here, olefin-based polymers include polyethylene (low pressure, medium pressure, high pressure), linear low density polyethylene, polyolefins such as polypropylene and boribene, and comonomers (vinyl ester, unsaturated carboxylic acid) capable of copolymerizing olefins with the olefins. Acid ester), for example, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer and the like. 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 0.0001 to 0.0001 or less 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.

Among these adhesive resins, the adhesiveness for EVOH has been insufficient until now, and the adhesive for nylon which cannot be used for a multilayer structure with EVOH, especially for a co-extruded multilayer structure. It can be said that the present invention is significant from the viewpoint that the conductive resin can be used for a multilayer structure with EVOH. With the development of such a resin composition comprising EVOH, the choice of adhesive resins that can be used for coextrusion molding with EVOH has been expanded. Further, the resin composition comprising the EVOH of the present invention,
Of course, since it shows extremely high adhesive performance with the conventional adhesive resin for EVOH, it is possible to reduce the thickness of the adhesive resin layer more than before, as long as the performance of the molded product is not hindered.
From this viewpoint, the significance of the present invention is great.

The method of coextrusion of the composition of the present invention with a thermoplastic resin may be any of a multi-manifold merging T-die method, a feed block 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 thus obtained co-extruded multilayer structure and co-injected multilayer structure have few fish eyes, are transparent, and have few streaks. Therefore, the materials for food containers, for example, deep drawn containers, cup-shaped containers, bottles, etc. And the like.

[0053]

EXAMPLES Hereinafter, the present invention will be described in more detail by way of 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) Determination of the content of acetic acid (A) 20 g of a dry chip as a sample was placed in 100 ml of ion-exchanged water.
And extracted by heating at 95 ° C. for 6 hours. The extract was subjected to neutralization titration with N / 50 NaOH using phenolphthalein as an indicator to quantify the content of acetic acid (A).

(2) Determination of alkali metal salt (B) and alkaline earth metal salt (E) (quantification of Na, K, Mg ions) 10 g of a dry chip as a sample is put into 50 ml of 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 ions, K ions, and Mg ions were quantified. The column used was ICS-C25 manufactured by Yokogawa Electric Corp., and the eluents were 5.0 mM tartaric acid and 1.0 mM 2,2.
An aqueous solution containing 6-pyridinedicarboxylic acid was used. In addition,
Calibration curves prepared with aqueous sodium chloride solution, aqueous potassium chloride solution and aqueous magnesium chloride solution were used for the determination. From the amounts of Na ion, K ion and Mg ion thus obtained, the amounts of the alkali metal salt (B) and the alkaline earth metal salt (E) in the dried chip were obtained in terms of the amount of metal element.

(3) Determination of Phosphate Compound (C) 10 g of a dry chip 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. The column used was ICS-A23 manufactured by Yokogawa Electric Corporation, and the eluent was 2.5 m
An aqueous solution containing M sodium carbonate and 1.0 mM sodium bicarbonate 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 phosphate compound (C)
Was obtained in terms of phosphate groups.

(4) Determination of Boron Compound (D) 100 g of a dry chip as a sample was put in a magnetic crucible and 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 (D) was obtained in terms of the amount of boron element.

(5) Adhesion The T-peel strength between the ethylene-vinyl alcohol copolymer / adhesive resin immediately after the formation of the three-layer five-layer film obtained by coextrusion molding was measured at 20 ° C.-65% RH. Below, it measured using the autograph (tension speed 250mm / min). The value was determined as follows based on the peel strength. A: 1000 g / 15 mm or more B: 1000-700 g / 15 mm C: 700-400 g / 15 mm D: less than 400 g / 15 mm

(6) Single-Layer Film Formation Test (6-a) Generation of Bubbles Single-layer film formation of EVOH was carried out using a sample chip.
0 μm or more) were counted and converted to around 1.0 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 (6-b) Long-run property A single-layer film formation of EVOH was performed using a sample chip, and the gel of the film after 8 hours. Shape (about 100 visible to the naked eye)
μm or more) were counted and converted to around 1.0 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 (6-c) Amount attached in die After performing a single-layer film formation of EVOH for 8 hours using a sample chip, MI = The EVOH resin in the extruder is reduced by 1 LDPE to 1
After the replacement over time, the weight of the EVOH thermally degraded resin adhered to the inside of the die was measured. It was determined as follows based on the weight. A; less than 1 g B; 1 to 5 g C; 5 to 10 g D; 1
0g or more

(7) Coloring resistance 8 g of the dried chips to be used as samples were sandwiched between hot plates (Sindoh table-top test press YS-5) heated to 230 ° C., and the gap between the hot plates was maintained at 5 mm for 10 minutes. After heating, the degree of coloration was determined with the naked eye and determined as follows. A: No coloring B: Slightly yellowing C: Yellowing D: Intense coloring

(8) 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. (8-a) Coloring resistance The film was wound around a paper tube, and the degree of coloring of 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 (8-b) Occurrence of bumps Gel-like bumps of a film after one hour of monolayer film formation (approximately 100 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

(9) Intrinsic Viscosity 0.20 g of a sample chip of a resin composition composed of EVOH was precisely weighed, and this was weighed with water-containing phenol (water / phenol = 15).
/ 85 wt%) is dissolved in 40 ml by heating at 60 ° C. for 3 to 4 hours, and measured at 30 ° C. with an Ostwald viscometer (t0 = 90 seconds). I asked. [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 45% methanol solution of an ethylene-vinyl acetate copolymer having an ethylene content of 38 mol% was charged into a saponification reactor.
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 chip having a length of about 5 mm and a length of about 5 mm was obtained. The operation of removing the obtained chip with a centrifuge and further adding a large amount of water to remove the liquid was repeated.

3.5 kg of a water-containing chip of the ethylene-vinyl alcohol copolymer thus obtained was added to 0.20 acetic acid.
g / L, 1.32 g / L of sodium acetate, 0.14 g / L of potassium dihydrogen phosphate, and 13 L of an aqueous solution containing boric acid of 0.35 g / L at 25 ° C. for 6 hours. After immersion, the mixture was drained and dried at 80 ° C. for 3 hours and subsequently at 107 ° C. for 24 hours using a hot-air drier to obtain dried chips.

The content of acetic acid in the obtained dried chips was 9
0 ppm, alkali metal salt content is 5 in metal element conversion
The content of the phosphoric acid compound (C) was 50 ppm in terms of a phosphate group, and the content of the boron compound (D) was 280 ppm in terms of a boron element. The MFR of the obtained chip was 2.1 g / 10 min.

Using the dried chips obtained, LLDPE /
Adhesive resin / ethylene-vinyl alcohol copolymer composition / adhesive resin / LLDPE three-layer, five-layer coextruded film (thickness 50/10/10/10/50; unit: μm) was formed. Here, as LLDPE, "Ultzex 3520L" manufactured by Mitsui Chemicals, Inc. MI = 2.1 g / 10 min (2
10 ° C., 2160 g load) was converted to “Admer NF308”, a maleic anhydride-modified polyethylene manufactured by Mitsui Chemicals, as an adhesive resin, MI = 1.7 g / 10 min (190 ° C.,
2160 g load), and an adhesive resin｝ for nylon was used.
Ethylene-vinyl alcohol copolymer composition, LLDP
E. The extrusion temperature of the adhesive resin is 220 ° C. and 170 ° C., respectively.
C. and 170.degree. C., and the die temperature was set at 220.degree. The extruder and T-die specifications for each resin are as follows. 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
(Toyo Seiki Co., Ltd.) T-die; 300mm width, 3 types, 5 layers (Plastic Engineering Laboratory) Also, the cooling roll temperature is 50 ° C and the take-up speed is 4m.
/ Min. Set to. The adhesion between the ethylene-vinyl alcohol copolymer composition / adhesive resin immediately after film formation was determined to be A.

Using the obtained dried chip, a single layer film of EVOH was formed, and tests were performed on generation of bumps, long run property, and die adhesion amount. The L / D ratio of the screw used for single-layer film formation of EVOH was 20, and the compression ratio was 4.0. The extruder and T-die specifications used in this test are as follows. Extruder: Single screw extruder D20 / 20 (manufactured by Toyo Seiki) T-die: 300 mm width Straight hanger type (manufactured by Toyo Seiki) Extrusion temperature: C1 / C2 / C3 / die = 180/220 /
At 220/220 ° C., the test results for the occurrence of spots and the long-running property were both A, and the test result for the die adhesion amount was B.

Using the obtained dried chips, a test for coloring resistance was carried out by the method described above. The test result of the coloring resistance was 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 5 and Comparative Examples 1 to 7 EVOH having an intrinsic viscosity shown in Table 2 was used as the EVOH after saponification, washing, and liquoring. Table 1 shows the composition of the solution in which the EVOH was immersed. A dried chip was prepared in the same manner as in Example 1 except that the dry chip was changed as shown. Table 2 shows the composition of the dried chips, and Table 3 shows the evaluation results.

[0071]

[Table 1]

[0072]

[Table 2]

[0073]

[Table 3]

The EVOH of the present invention obtained in Examples 1 to 5
The resin composition was excellent in adhesiveness, low in occurrence of gels and bumps, excellent in long-run properties, good in recoverability, and less colored during recovery. In Comparative Examples 1 and 2 in which the content of the phosphoric acid compound (C) was less than 10 ppm in terms of phosphoric acid radical, the coloring resistance and the recoverability were extremely poor. In Comparative Example 3, which contained the boron compound (D) and had a content of the alkali metal (B) of not more than 500 ppm in terms of the metal element, sufficient adhesion could not be obtained.
In Comparative Example 4 in which the boron compound (D) was not contained and the content of the alkali metal (B) was less than 500 ppm in terms of a metal element, the effect of improving the adhesiveness, which was the main subject of the present invention, was slightly inferior, and the occurrence of bumps and long run Both of the evaluation items of the properties and the die adhesion amount were slightly inferior. In Comparative Example 5 in which the content of the alkali metal (B) exceeded 2000 ppm in terms of a metal element, the color resistance and the recoverability were significantly reduced, and the long-run property was also unsatisfactory. Further, in Comparative Example 6 in which the acetic acid content exceeds 500 ppm, the occurrence of bumps,
Significant deterioration was observed in most evaluation items such as long run property and die adhesion amount, and the adhesive property was also sharply reduced. Furthermore, in Comparative Example 7 in which the acetic acid content was less than 10 ppm, the coloring resistance and the recoverability were poor.

[0075]

EFFECTS OF THE INVENTION A resin composition comprising an ethylene-vinyl alcohol copolymer, which is very excellent in adhesiveness, has little occurrence of gels and bumps, has excellent long-run properties, has good recoverability, and has little coloring at the time of recovery. A multilayer structure using the same can be provided. Such a resin composition has extremely excellent interlayer adhesion, and is extremely effective for coextrusion molding with a base material such as polyolefin.

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Claims (6)

[Claims] 1. An acetic acid (A) of 10 to 500 ppm and an alkali metal salt (B) of 500 to 2000 p in terms of a metal element.
pm, the phosphate compound (C) is 10 to 50 in terms of phosphate group.
A resin composition comprising an ethylene-vinyl alcohol copolymer containing 0 ppm. 2. The resin composition according to claim 1, which contains the boron compound (D) in an amount of 20 to 2000 ppm in terms of boron element. 3. The resin composition according to claim 1, wherein the content (ppm) of the alkali metal salt (B) is 3 to 20 times the content (ppm) of the acetic acid (A). object. 4. An MFR for a heat treatment time of 10 hours to 100 hours when heat-treated at 220 ° C. in a nitrogen atmosphere.
(Measured at 230 ° C-10.9kg)
max) and the MFR (2
The resin composition according to any one of claims 1 to 3, which satisfies the following formula (1) in a relationship of (measured at 30 ° C-10.9 kg; MFR0). 0.1 <MFRmax / MFR0 <10 (1) 5. A resin composition for coextrusion molding comprising the resin composition according to claim 1. 6. A multilayer structure comprising at least one layer comprising the resin composition according to claim 1.