JP2001047569A - Multilayer container - Google Patents

Abstract

(57) [Problem] To provide a multilayer container excellent in impact delamination resistance, appearance such as transparency and transparency, gas barrier properties, and the like. SOLUTION: A specific saponified ethylene-vinyl acetate copolymer is used as an intermediate layer, and layers of a thermoplastic polyester resin are arranged on both sides thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a multilayer container comprising a saponified ethylene-vinyl acetate copolymer (hereinafter abbreviated as EVOH) and a polyester resin.

[0002]

2. Description of the Related Art In general, EVOH is excellent in transparency, gas barrier property, fragrance retention, solvent resistance, oil resistance and the like.
It is used by being molded into films and sheets of industrial chemical packaging materials, agricultural chemical packaging materials, etc., or containers such as bottles. In particular, the moisture proof properties of the containers, the barrier properties of carbon dioxide and aroma components, the mechanical properties, etc. EVO for the purpose of improving performance
A laminate in which a polyester-based resin (mainly PET) is laminated on both surfaces of H is used. In recent years, it has attracted attention as a pressure-resistant bottle for soft drinks and alcoholic beverages containing carbonic acid. On the other hand, PET has excellent transparency and rigidity, moderate gas barrier properties and aroma retention properties, and is widely used for containers for carbonated drinks and soft drinks, but requires advanced gas barrier properties for beer, wine, etc. The gas barrier property is insufficient for the intended use, and as described above, it can be used as an excellent gas barrier container by lamination with EVOH.

However, in general, a thermoplastic polyester resin such as PET and EVOH have poor adhesiveness, and are typically represented by JP-A-59-188433 in order to increase their delamination strength and delamination resistance. Therefore, it is necessary to interpose a specific adhesive resin between the layers.
However, recently PET has been recycled and reused, and if an adhesive resin exists between layers,
Separation of PET and EVOH becomes difficult, and as a result, there arises a problem that the quality of recycled PET deteriorates, and it is difficult to be accepted in the market.

Therefore, without using such an adhesive resin, E
A multilayer container in which a polyester-based resin (PET) is laminated on both sides of VOH is desired. As a laminate used for such a multilayer container, a laminate of PET / EVOH / PET (Japanese Patent Laid-Open No. 61-173924) is used. ), A laminate of PET / regrind layer / EVOH / regrind layer / PET (JP-A-62-28332), PET / EV
OH (two-type blend) / PET laminate
271831, JP-A-2-139237), PET / EVOH (two types blend) / PET / E
VOH (two types blend) / PET laminated body
204736), PET / EVOH (other resin blend) / PET / EVOH (other resin blend) / PET
(JP-A-11-79156) has been proposed.

[0005]

However, the laminates described in JP-A-61-173924, JP-A-62-28332 and JP-A-2-139237 suffered an impact force. In this case, delamination resistance (impact delamination resistance), particularly its performance at low temperatures is insufficient. Also, JP-A-62-271831 and JP-A-1-20
Also in the laminates described in JP-B-4736 and JP-A-11-79156, although the impact delamination is improved to some extent, the gas barrier property is reduced and the transparency and transparency of the container are deteriorated. Has a point,
There is a need for a multilayer container of EVOH and PET which is excellent in appearance such as impact delamination, transparency and transparency, and gas barrier properties.

[0006]

In view of this situation, the present inventor has conducted intensive studies on a multilayer container made of EVOH and PET. As a result, the EVOH was used as an intermediate layer, and thermoplastic polyester was placed on both sides of the intermediate layer. A multi-layer container comprising a base resin layer, wherein the EVOH satisfies the following formula (1) and at least 10 to 10,000 ppm of at least one selected from alkali metals, alkaline earth metals and boron. The inventors have found that the object can be achieved, and have completed the present invention.

200−1.5 × Et ≦ Tm ≦ 225−1.5 × Et (1) Here, Tm is a differential scanning calorimeter (DSC) of EVOH.
The melting peak temperature (° C.) measured by
Represents the ethylene content (mol%) in the sample. Note that D
In the measurement of SC, it is measured under the condition of a heating rate of 10 ° C./min.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The EVOH used for the intermediate layer of the multilayer container of the present invention needs to satisfy the following formula (1). If not, the effect of the present invention cannot be obtained.

200−1.5 × Et ≦ Tm ≦ 225−1.5 × Et (1) Here, Tm is a melting peak temperature (° C.) measured by DSC of EVOH, and Et is in EVOH. Represents the ethylene content (mol%) of each.

That is, the ethylene content in EVOH and EV
It is necessary to adjust the relationship with the melting peak temperature of OH.
The ethylene content of the EVOH used in the present invention is not particularly limited, but usually one having an ethylene content of 10 to 70 mol% (further 20 to 60 mol%, particularly 25 to 55 mol%) is used. The ethylene content is 10 mol%
If less, the gas barrier property at high humidity and the melt moldability are reduced,
Conversely, if it exceeds 70 mol%, sufficient gas barrier properties cannot be obtained, which is not preferable for the use of the multilayer container of the present invention.

In adjusting the melting peak temperature of EVOH so as to satisfy the above equation (1) in the above range of ethylene content, there is no particular limitation.
A method of adjusting the saponification reaction during the production of EVOH to leave a certain amount of acetyl groups, a method of re-acetylating EVOH with acetic anhydride, a method of oxidatively decomposing EVOH with hydrogen peroxide, etc., A method of modifying with about ~ 18 aliphatic carboxylic acids and their esters, amides, etc., EV
OH to polyhydric alcohol (polyglycerin, trimethylolpropane, sorbitol, pentaerythritol, etc.)
And the like.

The EVOH used in the present invention only has to satisfy the expression (1) as described above, and other conditions are not limited.
The saponification degree is preferably 90 mol% or more (more preferably 95 mol% or more). When the saponification degree is less than 90 mol%, the gas barrier properties, heat stability, moisture resistance, etc. are lowered, which is not preferable.
Also, the melt flow rate (MFR) of EVOH (21
0 ° C., load 2160 g) is 0.1 to 100 g / 10 min (further 0.5 to 50 g / 10 min, especially 1 to 20 g / min).
10 minutes) is preferable, and when the melt flow rate is smaller than the range, the inside of the extruder becomes in a high torque state at the time of molding, so that extrusion processing becomes difficult. It is not preferable because the mechanical strength of the container is reduced.

The EVOH used in the present invention may be obtained by copolymerizing an ethylenically unsaturated monomer copolymerizable as long as the effects of the present invention are not impaired. Olefins such as 1-butene and isobutene, unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, (anhydrous) phthalic acid, (anhydrous) maleic acid, (anhydrous) itaconic acid, or salts thereof, or having 1 to 1 carbon atoms
8, mono- or dialkyl esters, acrylamide, N-alkylacrylamide having 1 to 18 carbon atoms,
N, N-dimethylacrylamide, 2-acrylamidopropanesulfonic acid or a salt thereof, acrylamidopropyldimethylamine or a salt thereof or 4
Acrylamides such as quaternary salts, methacrylamide, N-alkylmethacrylamide having 1 to 18 carbon atoms, N, N-dimethylmethacrylamide, 2-methacrylamidopropanesulfonic acid or a salt thereof, methacrylamidopropyldimethylamine or an acid salt thereof Or methacrylamides such as quaternary salts thereof, N-vinylpyrrolidone, N-
N- such as vinylformamide and N-vinylacetamide
Vinyl amides, acrylonitrile, vinyl cyanide such as methacrylonitrile, C1-C18 alkyl vinyl ether, hydroxyalkyl vinyl ether, vinyl ether such as alkoxyalkyl vinyl ether, vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, Vinyl halides such as vinyl bromide, vinyl silanes such as trimethoxyvinyl silane, allyl acetate, allyl chloride, allyl alcohol, dimethyl allyl alcohol, trimethyl- (3-acrylamido-3-dimethylpropyl) -ammonium chloride, acrylamide-2 -Methylpropanesulfonic acid and the like.

Further, the EVOH used in the present invention contains at least one selected from the group consisting of alkali metals, alkaline earth metals and boron in an amount of 10 to 10000 ppm (more preferably 20 to 10,000 ppm).
5000 ppm, especially 50 to 1000 ppm), and if the content is less than 10 ppm, the impact delamination resistance becomes insufficient, and on the contrary, 10,000 p
If it exceeds pm, the appearance of the obtained multilayer container deteriorates, and the object of the present invention cannot be achieved.

Examples of such alkali metals and alkaline earth metals include sodium, potassium, calcium, magnesium, manganese, copper, cobalt, zinc and the like.
Above all, sodium, potassium, calcium, and magnesium are preferable. When these metals are contained, it is preferable to contain them as metal salts such as fatty acids such as acetic acid and inorganic acids such as boric acid and phosphoric acid.

It is preferable that boron is contained as a boron compound.
Boric acid, calcium borate, cobalt borate, zinc borate (zinc tetraborate, zinc metaborate, etc.), potassium aluminum borate, ammonium borate (ammonium metaborate, ammonium tetraborate, ammonium pentaborate, Cadmium borate (cadmium orthoborate, cadmium tetraborate, etc.),
Potassium borate (potassium metaborate, potassium tetraborate, potassium pentaborate, potassium hexaborate, potassium octaborate, etc.), silver borate (silver metaborate, silver tetraborate, etc.), copper borate (borate Cupric acid, copper metaborate, copper tetraborate, etc.), sodium borate (sodium metaborate,
Sodium diborate, sodium tetraborate, sodium pentaborate, sodium hexaborate, sodium octaborate, etc., lead borate (lead metaborate, lead hexaborate, etc.), nickel borate (nickel orthoborate, Nickel diborate, nickel tetraborate, nickel octaborate, etc., barium borate (barium orthoborate, barium metaborate, barium diborate, barium tetraborate, etc.), bismuth borate, magnesium borate (orthoborate) Magnesium borate, magnesium diborate, magnesium metaborate, trimagnesium tetraborate, pentamagnesium tetraborate, etc., manganese borate (manganese borate, manganese metaborate, manganese tetraborate, etc.), lithium borate (Lithium metaborate, lithium tetraborate, lithium pentaborate, etc.) Examples include borate minerals such as carnite, inyoite, dwarf stone, diatomite, zeyberite, and zeyberite, and are preferably boric acid, borax, sodium borate (sodium metaborate, sodium diborate, sodium tetraborate) , Sodium pentaborate, sodium hexaborate, sodium octaborate, etc.).

It is to be noted that the alkali metal (EV) may be contained in EVOH so as to contain an alkali (earth) metal salt of boric acid or an alkali (earth) metal salt such as boric acid and a fatty acid or phosphoric acid. When at least two kinds of alkaline earth metals and boron are contained, the total amount needs to be within the range of the above contents.

The above alkali metals, alkaline earth metals,
When boron is contained in EVOH, EVOH (pellet, powder, or the like) is immersed in an aqueous solution of the above-mentioned metal salt compound or boron compound, and then dried,
This can be achieved by adding the above-mentioned metal salt compound or boron compound (aqueous solution) to a water / alcohol solution of H and then removing the solvent. Of these, alkali metals and / or boron are preferably used because they are particularly excellent in the effects of the present invention.

The resin used in the thermoplastic polyester resin layer disposed on both sides of the EVOH layer is not particularly limited. For example, aromatic dicarboxylic acids or their alkyl esters and glycols are mainly used. Examples include a condensation polymer as a component, and typically, a polymer having ethylene terephthalate as a main repeating unit is preferable. Further, it is possible to contain a copolymer component within a range that does not significantly impair workability, strength, and the like. Examples of such a copolymer component include isophthalic acid and diphenyl-4,4′-dicarboxylic acid as acid components. , Diphenoxyethane dicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7
-Aromatic dicarboxylic acids such as naphthalenedicarboxylic acid and their ester-forming derivatives, aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid and succinic acid and their ester-forming derivatives, cyclohexanedicarboxylic acid, hexahydroterephthalic acid Alicyclic dicarboxylic acids such as acids and their ester-forming derivatives, p-
In addition to oxyacids such as oxybenzoic acid and oxycaproic acid and their ester-forming derivatives, trimellitic acid,
Pyromellitic acid and the like can be mentioned. Examples of the glycol component include aliphatic glycols such as diethylene glycol, trimethylene glycol, tetramethylene glycol, and neopentyl glycol; alicyclic glycols such as 1,4-cyclohexanedimethanol; bisphenol A; and alkylene oxide adducts of bisphenol A. Such as aromatic glycol, polyethylene glycol, polypropylene glycol, polyalkylene glycol such as polytetramethylene glycol, glycerin,
Examples thereof include 1,3-propanediol and pentaerythritol.

The content of the ethylene terephthalate unit is
It is about 75 to 100 mol%, preferably about 85 to 100 mol%. The preferred intrinsic viscosity (measured at a temperature of 30 ° C. in a 50% by weight / 50% by weight mixed solvent of phenol and tetrachloroethane) is 0.5 to 1.3 dl / g.
(Further, 0.65 to 1.2 dl / g).

Next, representatively, there are exemplified those having ethylene terephthalate as a main repeating unit. It is also possible to contain the same copolymer component as above,
The content of ethylene terephthalate is about 75 to 100 mol%, preferably about 85 to 98 mol%. Also,
Preferred intrinsic viscosity is 0.4 to 1.2 dl / g (further 0.55 to 1.0 dl / g).

It is also preferable to use a blend of the above-mentioned ethylene terephthalate-based polyester resin and ethylene terephthalate-based resin in terms of improving gas barrier properties, ultraviolet shielding properties and melt moldability. The content of the ethylene terephthalate-based polyester resin is 5 to 90% by weight, more preferably 15 to 85% by weight.
It is 5 to 10% by weight, further 85 to 15% by weight.

Further, within a range that does not significantly impair various characteristics,
Other thermoplastic resins and additives can be blended, and examples of the thermoplastic resin include MXD-6 nylon, polycarbonate, polyarylate, and liquid crystal polymer.

Although the mechanism of action of the present invention is not clear,
Regarding impact delamination resistance, EVOH having a structure that satisfies the formula (1) exhibits physical adhesion to a thermoplastic polyester resin, and is formed from alkali metals, alkaline earth metals, and boron in EVOH. It is presumed that at least one selected from the group acts catalytically on the chemical adhesion between the EVOH and the thermoplastic polyester-based resin, and the synergistic effect thereof improves the impact delamination resistance of the multilayer container.

[0025] The multilayer container of the present invention comprises an EVOH as described above.
, And a layer of thermoplastic polyester resin disposed on both sides of the intermediate layer. A method for producing such a multilayer container will be described.

In producing the multilayer container of the present invention, a) a multilayer structure (sheet, film, or sheet) in which a thermoplastic polyester resin is laminated on both sides of a layer made of EVOH.
Parison, etc.) and then forming into a container, b)
A method in which EVOH and a thermoplastic polyester resin are co-injected into a co-injection molding machine or the like to directly form a multilayer container, and the like.

In the method (a), first, a thermoplastic polyester-based resin is laminated on both sides of a layer made of EVOH to produce a multilayer structure.
For example, a method of melt-extruding a thermoplastic polyester resin on a film or sheet made of EVOH, and a method of melt-extruding EVOH on a layer of a thermoplastic polyester resin,
A method of co-extrusion of EVOH and a thermoplastic polyester resin, or a method of co-injection of both resins,
H and a film or sheet made of a thermoplastic polyester resin and an organic titanium compound,
A dry lamination method using a known adhesive such as an isocyanate compound, a polyester-based compound, or a polyurethane compound may, for example, be mentioned.

Next, the obtained multilayer structure is molded into a container, and it is preferable to perform a heat-stretching treatment in this molding. It is possible to obtain a multilayer container which is free from cracks, uneven thickness and the like, and is excellent in gas barrier properties and transparency.

Here, the heat-stretch molding means that the multilayer structure is uniformly heated by various heaters, and the chuck, plug,
It refers to the operation of uniformly forming into various shapes by vacuum force, pneumatic force or the like.

The heating stretching may be any of uniaxial stretching and biaxial stretching. The heating stretching method includes a roll stretching method, a tenter stretching method, a tubular stretching method, a stretching blow method, a deep drawing method, Vacuum forming method, pressure forming method, vacuum pressure forming method and the like can be adopted. In the case of biaxial stretching, any of a simultaneous biaxial stretching method and a sequential biaxial stretching method can be adopted. The temperature of the multilayer structure during the heat stretching is 80 to 17
The temperature is selected from the range of 0 ° C, preferably about 100 to 160 ° C.

In the present invention, it is particularly effective in the field of hot stretch molding of thick articles such as obtaining hollow containers such as bottles, tanks and tubes by blow molding, and the production method is not particularly limited. Instead, a direct blow molding method, an injection blow molding method, a biaxial stretch blow molding method, and the like can be mentioned. Further, as for the biaxial stretch blow molding method, a cold parison method and a hot parison method can be mentioned. Further, it is preferable to further heat-treat the hollow container obtained by blow molding, since the impact delamination property and the gas barrier property are improved. The heat treatment temperature is 100 to 240 ° C., and the heat treatment time is 1 second or more.

In the method (b), a multilayer container such as a cup or a tray can be directly obtained using a co-injection molding machine or the like without heating and stretching. It is also preferable to further heat-treat the obtained multilayer container in the same manner as in a).

Thus, the multilayer container of the present invention can be obtained.
When the layer made of is a and the layer made of a thermoplastic polyester resin is b, not only the three-layer structure of but also b / a / b
/ A, b / a / b / a / b, b / a / b / a / b / a,
Any combination such as b / a / b / a / b / a / b is possible. Furthermore, it is also possible to provide a regrind layer or a thermoplastic resin layer other than EVOH or thermoplastic polyester resin.

The multilayer container of the present invention can provide excellent impact delamination resistance without using an adhesive resin between the EVOH layer and the thermoplastic polyester resin layer. If necessary, it is also possible to use an adhesive resin, is not particularly limited as the adhesive resin,
Although various types can be used, generally, an unsaturated carboxylic acid or its anhydride is chemically bonded to an olefin-based polymer (the above-mentioned polyolefin-based in a broad sense) by an addition reaction, a graft reaction, or the like. Examples include a modified olefin polymer containing a carboxyl group obtained by the method, specifically, maleic anhydride graft-modified polyethylene, maleic anhydride graft-modified polypropylene,
Maleic anhydride graft-modified ethylene-ethyl acrylate copolymer, maleic anhydride graft-modified ethylene
One or a mixture of two or more selected from vinyl acetate copolymers and the like can be mentioned as a preferable example. At this time, the amount of the unsaturated carboxylic acid or its anhydride contained in the olefin polymer is preferably 0.001 to 1% by weight, more preferably 0.01 to 0.5% by weight.
If the amount of modification in the modified product is small, the effect of improving interlayer adhesion is poor, and if it is too large, a crosslinking reaction occurs, and moldability may deteriorate, which is not preferable. Further, in the present invention, it is possible to blend a with b and b with b, or to blend at least one of a and b with a resin that improves the adhesion between the two layers.

Further, the thickness of each layer of the multilayer container cannot be determined unconditionally depending on the layer constitution and the use when the container is used. However, usually, the thickness of the EVOH layer is 1 to 100 μm (more preferably 5 to 100 μm).
50 μm), and 30 to 3000 μm (more preferably 50 to 1000 μm) for the thermoplastic polyester resin layer.
When the thickness of the EVOH layer is less than 1 μm, the gas barrier property becomes insufficient and the thickness control becomes unstable. On the other hand, when the thickness exceeds 100 μm, the impact resistance is poor, and it is not economically preferable. When the thickness of the resin layer is less than 30 μm, the rigidity is insufficient. On the other hand, when the thickness exceeds 3000 μm, the weight increases, which is not economical and is not preferable.

In the present invention, a multilayer container is prepared as described above. Such EVOH or thermoplastic polyester resin may contain a plasticizer, a lubricant, a heat stabilizer and the like within a range not departing from the object of the present invention. , Light stabilizers, ultraviolet absorbers, antioxidants, coloring agents, antistatic agents, surfactants,
Additives such as antibacterial agents and inorganic fillers can be blended, or other resins can be blended. In particular, a hydrotalcite-based compound, a hindered phenol-based, a hindered amine-based heat stabilizer, and a metal salt of a higher aliphatic carboxylic acid can also be added as a gel generation inhibitor.

Further, it is also preferable to add an oxygen absorbent to the EVOH or the thermoplastic polyester-based resin in that the oxygen barrier property from the outside of the multilayer container and the residual oxygen removal property in the inside are improved. Examples of the oxygen absorber include inorganic iron absorbers, reduced iron powders, and those obtained by adding a water-absorbing substance and an electrolyte thereto, aluminum powder, potassium sulfite, and photocatalytic titanium oxide. Ascorbic acid, furthermore, fatty acid esters and metal salts thereof, hydroquinone, gallic acid, polyphenols such as hydroxyl-containing phenol aldehyde resins, bis-salicylaldehyde-imine cobalt, tetraethylene pentamine cobalt, cobalt-Schiff base complex , Porphyrins, macrocyclic polyamine complexes, polyethyleneimine-
Coordination conjugates of nitrogen-containing compounds such as cobalt complexes and transition metals, terpene compounds, reactants of amino acids and hydroxyl group-containing reducing substances, triphenylmethyl compounds, etc.
As a polymer-based oxygen absorbent, a coordination bond between a nitrogen-containing resin and a transition metal (eg, a combination of MXD nylon and cobalt), and a blend of a tertiary hydrogen-containing resin with a transition metal (eg, polypropylene and cobalt) Combinations), blends of carbon-carbon unsaturated bond-containing resins and transition metals (eg:
A combination of polybutadiene and cobalt), a photo-oxidatively degradable resin (eg, polyketone), an anthraquinone polymer (eg, polyvinyl anthraquinone), and the like. Further, it is also preferable to add a photoinitiator (such as benzophenone), a peroxide supplement (such as a commercially available antioxidant) and a deodorant (such as activated carbon) to these compounds.

The multi-layer container of the present invention thus obtained can be used not only for general foods, but also for seasonings such as soy sauce, sauces, ketchup, mayonnaise, and dressings, fermented foods such as miso, vinegar, oil and fat foods such as salad oil, and sake. , Beer, mirin, whiskey, shochu, wine and other alcoholic beverages, carbonated drinks, juices, sports drinks, coffee drinks, oolong tea, tea, mineral water, and other soft drinks, cosmetics, pharmaceuticals, detergents, cosmetics, industrial chemicals, agricultural chemicals The multilayer container of the present invention is particularly useful for beverages such as beer, wine, carbonated beverages and juices, and containers for seasonings such as sauces and dressings, particularly bottles.

[0039]

The present invention will be specifically described below with reference to examples. In the examples, “parts” and “%” are based on weight unless otherwise specified.

Example 1 EVOH [Ethylene content (Et) 44 mol%, degree of saponification 99.6 mol%, MI 6 g / 10 min, melting point (T
m) A water / methanol mixed solution of 164 ° C.] is extruded into a water tank in the form of a strand, solidified, cut into a pellet by a cutter, washed with water, and further washed with acetic acid water to form a water-containing porous precipitate. I got

Next, the precipitate was washed with potassium acetate 0.1%.
The solution was poured into an aqueous solution containing 0.05% and dipotassium hydrogen phosphate 0.02%, stirred, dried, and dried to a water content of 0.2%.
%, EVOH pellets having a potassium content of 155 ppm.

After adding 6 parts of acetic anhydride to 100 parts of the EVOH and mixing well, the mixture is supplied to a co-rotating twin-screw extruder, re-acetylated at a melting temperature of 280 ° C., extruded into strands, and cooled. And solidified by cooling with a pelletizer. The target EVOH pellet [ethylene content (Et) 44 mol%, saponification degree 96.1 mol%, MI
5.5 g / 10 min, melting point (Tm) 149 ° C].

When the ethylene content (Et) of the EVOH pellets, 44 mol%, was substituted into the expression (1) in the text, 134 ≦ Tm ≦ 159 was satisfied, thereby satisfying the expression (1).

The EVOH pellets obtained above and a thermoplastic polyester resin (polyethylene terephthalate,
Using a uniaxial stretch orientation blow molding machine (“ASB-50T” manufactured by Nissei ASB Machine Co., Ltd.) using Nippon Unipet “Unipet RT553C”), a thermoplastic polyester resin / EVOH / thermoplastic polyester resin Multilayer parison of two types and three layers (thickness configuration: [inside] 1400/150
/ 1450 [outside] μm, height: 9.2 cm) by co-injection molding, followed by preheating the multilayer parison,
Biaxial stretching orientation blow molding was performed to obtain a multi-layer bottle (multi-layer container) having an inner volume of 500 cc (body diameter 7.5 cm, height 18 cm).

In addition, the main molding conditions were as follows. Thermoplastic polyester resin plasticizing temperature: 270 to 275 ° C EVOH plasticizing temperature: 230 to 235 ° C Hot runner block temperature: 270 ° C Mold cooling temperature: 10 ° C Thermoplastic polyester resin injection pressure: 3.43 MPa EVOH injection pressure : 3.43 MPa Multilayer parison heating temperature: 160 ° C Multilayer parison heating time: 18 seconds Blow air pressure: 0.98 MPa The layer thickness of the bottle body of the obtained multilayer bottle is [inside] thermoplastic polyester resin / EVOH. / Thermoplastic polyester resin [outside] = 140/15/155
(Μm).

The following evaluation was performed on the bottle. (Appearance) The obtained multilayer bottle was visually observed and evaluated as follows. However, the transparency was evaluated based on the degree of cloudiness of the multilayer bottle itself, and the transparency was evaluated based on the degree of distortion of characters as viewed from the opposite side by applying printed paper to the body of the multilayer bottle. ○ −−− Both transparency and transparency are good △ −−− Transparency is good but transparency is poor × −−− Both transparency and transparency are poor

(Oxygen permeability) Bottle 1 under the conditions of a temperature of 23 ° C., a humidity of 100% RH inside the bottle, and a humidity of 50% outside the bottle
Oxygen permeability (cc / day) per unit is measured by an oxygen permeability measuring device (“OXTRAN10 / 50” manufactured by MOCON).
It measured using.

(Impact delamination resistance) Water (about 5
00cc), the mouth was sealed with a cap, and at 23 ° C. and 5 ° C., the body was horizontally leveled from a height of 1 m and dropped repeatedly on an iron floor surface 10 times each. The situation was visually observed and evaluated as follows. ◎ −−− No delamination was observed at all ○ −−− Slight delamination was observed △ −−− Slight delamination was observed × −−− Remarkable delamination was observed

Example 2 According to Example 1, a thermoplastic polyester resin / EV
A multilayer parison having two layers and five layers of OH / thermoplastic polyester resin / EVOH / thermoplastic polyester resin was produced by co-injection molding. Subsequently, the multi-layer parison was preheated and biaxially stretched and oriented blow-molded to obtain a multi-layer bottle (multi-layer container) having an inner volume of 500 cc, which was similarly evaluated.

The layer thickness of the body portion of the obtained multilayer bottle is [inside] [thermoplastic polyester resin / EVOH].
/ Thermoplastic polyester resin / EVOH / Thermoplastic polyester resin [outside] = 65/7/150/8/7
It was 0 μm.

Example 3 A methanol solution containing 50% of an ethylene-vinyl acetate copolymer having an ethylene content (Et) of 42 mol% was fed to the upper part of a saponification tray, and at the same time, a residue in the polymer was left. A methanol solution containing 0.008 equivalent of sodium hydroxide with respect to the acetic acid group was supplied from the top of the column. On the other hand, methanol was supplied from the lower part of the tower,
The saponification degree was 97.5 kg / cm ² G.
A mole% of EVOH was obtained.

The EVOH water / methanol mixed solution is extruded into a water tank in the form of a strand, solidified, cut with a cutter into pellets, washed with water, and further washed with acetic acid water to form a hydrous porous precipitate. I got

Next, the precipitate was put into an aqueous solution containing 0.06% of calcium acetate and stirred.
Dry to 0.12% water content, 65pp calcium content
m of the desired EVOH pellet [ethylene content (E
t) 42 mol%, saponification degree 97.5 mol%, MI 10 g
/ 10 min, melting point (Tm) 156 ° C.].

When the ethylene content (Et) 42 mol% of the EVOH pellets was substituted into the expression (1) in the text, 137 ≦ Tm ≦ 162 was satisfied, thereby satisfying the expression (1). Using the obtained EVOH, a multilayer container was obtained in the same manner as in Example 2, and the same evaluation was performed.

Example 4 EVOH [Ethylene content (Et) 38 mol%, degree of saponification 99.6 mol%, MI 3 g / 10 min, melting point (T
m) 173 ° C.] in a water / isopropyl alcohol mixed solution (water / isopropyl alcohol = 42/58 weight ratio, resin content 17%) in 100 parts of a 30% aqueous solution of hydrogen peroxide.
After adding 3 parts and reacting under stirring at 80 ° C. for about 20 hours, 3000 ppm of catalase was further added to remove residual hydrogen peroxide, to obtain an EVOH solution having a resin content of 15%. The solution is heated until the resin content of the solution becomes 35% to remove the solvent, extruded into a water tank in the form of a strand, solidified, cut with a cutter into pellets, washed with water, and further washed with acetic acid water. This gave a hydrous porous precipitate.

Next, the precipitate was washed with potassium acetate (0.1%).
After throwing into an aqueous solution containing 1% and stirring, it is dried and dried to obtain a target EVOH pellet having a water content of 0.2% and a potassium content of 65 ppm [ethylene content (Et) 38
Mol%, saponification degree 99.6 mol%, melting point (Tm) 150
° C].

Incidentally, when the ethylene content (Et) of 38 mol% of the EVOH pellets was substituted into the expression (1) in the text, 143 ≦ Tm ≦ 168, which satisfied the expression (1). Using the obtained EVOH, a multilayer container was obtained in the same manner as in Example 2, and the same evaluation was performed.

Example 5 In Example 2, PEN (polyethylene naphthalate) having a melt viscosity of 590 Pa · sec at a shear rate of 100 sec ⁻¹ and a melting point of 245 ° C. (measured by the DSC method) at 300 ° C. as a thermoplastic polyester resin. Was performed in the same manner except that was used to obtain a multilayer container of two kinds and five layers,
Evaluation was performed similarly.

Example 6 In Example 2, the water-containing porous precipitate was put into a 0.06% boric acid aqueous solution, stirred, dried, and dried to obtain an EVOH having a water content of 0.2% and a boron content of 320 ppm. A multilayer container was obtained in the same manner except that pellets were obtained, and evaluation was performed in the same manner.

Example 7 In Example 2, the water-containing porous precipitate was put into an aqueous solution containing 0.06% of boric acid and 0.06% of sodium acetate, stirred, dried, and dried. 0.2%, boron content 320ppm, sodium content 70ppm
A laminate was obtained in the same manner except that the EVOH pellet was used, and the evaluation was performed in the same manner.

Example 8 The same procedure as in Example 2 was repeated except that the thickness structure was changed so that the [inside] thermoplastic polyester resin layer (45 μm) / EVOH layer (7 μm) / thermoplastic polyester resin layer (150 μm)
m) / EVOH layer (8 μm) / thermoplastic polyester resin layer (90 μm)
Evaluation was performed similarly.

Comparative Example 1 An EVOH was obtained in the same manner as in Example 1 except that the re-acetylation treatment was not performed, and a multi-layer container was similarly obtained. The obtained EVOH had an ethylene content (Et) of 44 mol%, a degree of saponification of 99.6 mol%,
MI 6g / 10min (210 ° C, load 2160g), Tm
= 164 ° C., potassium content 155 ppm, Et
= 44 into the equation (1), 134 ≦ Tm ≦ 159
Did not satisfy the expression (1).

Comparative Example 2 An EVOH was obtained in the same manner as in Example 4 except that 22 parts of a 30% aqueous solution of hydrogen peroxide was added, and a multilayer container was obtained. In addition, the obtained EV
OH is ethylene content (Et) 38 mol%, saponification degree 99.6 mol%, Tm = 132 ° C., potassium content 65
ppm, and when Et = 38 is substituted into equation (1), 1
43 ≦ Tm ≦ 168, which did not satisfy the expression (1).

Comparative Example 3 EVO was performed in the same manner as in Example 1 except that the treatment was not performed in an aqueous solution of potassium acetate / dipotassium hydrogen phosphate.
H was obtained, a multilayer container was similarly obtained, and the evaluation was performed in the same manner. In addition, the obtained EVOH has an ethylene content (Et).
44 mol%, degree of saponification 96.1 mol%, MI 5.5 g /
10 minutes (210 ° C, load 2160g), Tm = 149 ° C
Substituting Et = 44 into the equation (1) gives 134 ≦
Tm ≦ 159 satisfied the expression (1), but did not include any of alkali metals, alkaline earth metals, and boron.

Comparative Example 4 An EVOH was obtained in the same manner as in Example 1 except that the treatment was carried out in an aqueous solution containing 3% of potassium acetate and 1% of dipotassium hydrogen phosphate. Evaluation was performed similarly. The obtained EVOH had an ethylene content (Et) of 44 mol%, a saponification degree of 96.1 mol%, and a MI of
5.5 g / 10 min (210 ° C., load 2160 g), Tm
= 149 ° C, and when Et = 44 was substituted into the expression (1), the expression (1) was satisfied with 134 ≦ Tm ≦ 159, but 11,000 ppm of potassium was contained.

Table 1 shows the evaluation results of the examples and comparative examples.

[Table 1] Appearance Oxygen permeability * Impact delamination resistance 23 ° C 5 ° C Example 1 ○ 0.03 ◎ ○ 〃 2 ○ 0.03 ◎ ◎ 〃 3 ○ 0.04 ◎ ○ ４ 4 ○ 0.02 ◎ ◎ 〃 5 ○ 0.03 ◎ ◎ 〃 6 ○ 0.03 ◎ ◎ 〃 7 ○ 0.03 ◎ ◎ 〃 8 ○ 0.03 ◎ ◎ Comparative Example 1 △ 0.02 ○ × △ 2 △ 0.15 ◎ ◎ ３ 3 ○ 0.03 ○ × ４ 4 × 0.05 ○ ○ * Unit is cc / day ・ atm (per multilayer bottle)

[0067]

The multilayer container of the present invention uses a specific EVOH as an intermediate layer and a layer of a thermoplastic polyester resin on both sides of the intermediate layer, so that the appearance such as impact resistance delamination, transparency and transparency can be obtained. Excellent in gas barrier properties, etc., very useful for containers for food and alcohol, beverages, cosmetics, pharmaceuticals, detergents, cosmetics, agricultural chemicals, industrial chemicals, especially beverages such as beer, wine, carbonated beverages, juices, Excellent for seasoning containers such as sauces and dressings, especially bottles.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) C08L 31/04 C08L 31/04 S 67/00 67/00 F term (reference) 3E067 AA03 AA11 AB01 AB26 AB81 AB96 BA03A BA07A BA10A BB14A BB18A BB25A CA04 CA05 CA11 GD08 4F100 AB01A AB09A AK41B AK41C AK68A BA02 BA03 BA06 BA10B BA10C GB16 JA04A JB16B JB16C JD02 JK06 JN01 4J002 BB221 CF031 GG01 CF041

Claims (1)

[Claims] An saponified ethylene-vinyl acetate copolymer is used as an intermediate layer, and a layer of a thermoplastic polyester resin is disposed on both sides of the intermediate layer. The saponified ethylene-vinyl acetate copolymer is represented by the following (1): A multilayer container which satisfies the formula and contains 10 to 10000 ppm of at least one selected from alkali metals, alkaline earth metals and boron. 200−1.5 × Et ≦ Tm ≦ 225−1.5 × Et (1) [Tm: melting peak temperature of a saponified ethylene-vinyl acetate copolymer measured by a differential scanning calorimeter (° C.) ), E
t: Ethylene content (mol%) of saponified ethylene-vinyl acetate copolymer]