JP2000094612A - Multilayer film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer film which retains excellent gas barrier properties even when exposed to high temperature and high moisture, and at the same time, has a good heat sealability and is applicable to various uses. SOLUTION: This multilayer film is composed of a polyalkylene terephthalate layer and an olefinic polymer layer which are laminated respectively with an adhesive layer containing an epoxidized diene block copolymer through a liquid crystalline polymer layer containing a thermotropic liquid crystalline polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer film comprising a liquid crystal polymer layer as a constituent element and having excellent heat resistance, gas barrier properties and heat sealing properties.

[0002]

2. Description of the Related Art Conventionally, a polypropylene film is bonded to both sides of a stretched film such as polypropylene or polyethylene terephthalate as a packaging film, or a film made of saponified ethylene-vinyl acetate copolymer, and maleic anhydride-modified polypropylene is bonded. Composite films laminated via layers are widely used. However,
Polypropylene films have insufficient oxygen gas barrier properties, and polyethylene terephthalate films have insufficient moisture barrier properties, that is, insufficient water vapor barrier properties. Further, in the above composite film, the oxygen gas barrier property of the film composed of the saponified ethylene-vinyl acetate copolymer is remarkably reduced due to moisture absorption. For example, after the retort sterilization treatment, the oxygen gas barrier property is reduced by about 10 to 40 times. Therefore, it is difficult to store foods and the like for a long period of time. Further, the composite film has insufficient heat resistance due to its constituent polymer.

A composite film in which a polypropylene film is laminated on both sides of a polyvinylidene chloride film via a layer made of an ethylene-vinyl acetate copolymer has also been proposed. According to this composite film, a polyvinylidene chloride film can secure oxygen gas barrier properties, and a polypropylene film can secure water vapor barrier properties. However, since a plasticizer or a stabilizer is usually added to polyvinylidene chloride to impart moldability, gas barrier properties are reduced. In addition, since the glass transition temperature of polyvinylidene chloride is low, it is plasticized as the temperature increases, and the gas barrier property at high temperatures decreases as described above, and the heat resistance is not sufficient due to the constituent polymer. On the other hand, polybutylene terephthalate and the like are known as films having excellent heat resistance. Therefore, it is conceivable to laminate the film and the polyvinylidene chloride film. However, since the melting point and decomposition temperature of polyvinylidene chloride are close to each other and decompose at about 180 to 200 ° C., it is difficult to form a laminated film by coextrusion with polybutylene terephthalate having excellent heat resistance. In addition, the above film cannot ensure heat sealing properties, and its use is significantly restricted.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to maintain excellent gas barrier properties even when exposed to high temperature and high humidity, and have heat sealing properties, and can be used for various applications. It is to provide a multilayer film.

[0005]

Means for Solving the Problems The present inventors have found that a thermotropic liquid crystalline polymer exhibits a high gas barrier property, and as a result of diligently studying the formation of a film, the present invention has been completed. That is, in the present invention, a polyalkylene terephthalate layer and an olefin-based polymer layer are laminated with an adhesive layer containing an epoxidized diene-based block copolymer via a liquid-crystalline polymer layer containing a thermotropic liquid-crystalline polymer. With a multilayer film
This is to solve the above-mentioned problem.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the present specification, a liquid crystalline polymer means a thermotropic liquid crystal polymer which is softened and flowable by heating, can be molded, and exhibits an anisotropic molten phase having a birefringence when melted, and a composition thereof. means.

[0007] A film is used to include all relatively thin, substantially flat structures, sometimes referred to in the art as sheets or the like.

[0008] Examples of the above-mentioned liquid crystalline polymer include polymers comprising the following components.

(1) One or two or more aromatic dicarboxylic acids and alicyclic dicarboxylic acids (2) One or two or more aromatic diols, alicyclic diols and aliphatic diols (3) Aromatic hydroxycarboxylic acids (4) One or more aromatic thiol carboxylic acids (5) One or more aromatic dithiols and aromatic thiol phenols (6) Aromatic hydroxyamines and aromatic diamines One or more.

The liquid crystalline polymer composed of the above-mentioned constituents includes: a) a polyester composed of the constituents (1) and (2); b) a polyester composed of the constituent (3); c) a polyester composed of the constituents (1) and (2) Polyester comprising 2) and (3), d) polythiol ester comprising component (4), e) polythiol ester comprising components (1) and (5), f) components (1) and (4) ) And (5), g) a polyesteramide comprising components (1), (3) and (5), h) a component (1), (2), (3) and (5) ) Is selected as a combination of polyesteramide and the like.

Although not included in the category of the combination of the above components, such a liquid crystalline polymer includes aromatic polyazomethine, and specific examples thereof include poly (nitrilo-2-methyl-1,4-phenylenenitrile). Ethyridine-1,4-
Phenyleneethylidyne), poly (nitriro-2-methyl-1,4-phenylenenitrylmethylidyne-1,4-phenylenemethylidyne), and poly (nitriro-2-chloro-1,4-phenylenenitrilomethylidyne-1) , 4-
Phenylenemethylidine) and the like.

Further, although not included in the category of the combination of the above components, such a liquid crystalline polymer includes a polyester carbonate. This polymer essentially contains 4-oxybenzoyl, dioxyphenyl, dioxycarbonyl and terephthaloyl units.

The aromatic dicarboxylic acids include terephthalic acid, 4,4'-diphenyldicarboxylic acid, 4,4 "
-Triphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, diphenylether-4,4'-dicarboxylic acid, diphenoxyethane-4,4'-dicarboxylic acid, diphenoxybutane-4,4'-dicarboxylic acid, diphenylethane -4,4'-dicarboxylic acid, isophthalic acid, diphenyl ether-3,3'-dicarboxylic acid, diphenoxyethane-3,3'-dicarboxylic acid, diphenylethane-3,3'-dicarboxylic acid, naphthalene-1,6 Aromatic dicarboxylic acids such as dicarboxylic acids; alkyl, alkoxy or halogen-substituted aromatic dicarboxylic acids such as chloroterephthalic acid, dichloroterephthalic acid, bromoterephthalic acid, methylterephthalic acid, dimethylterephthalic acid, ethylterephthalic acid, methoxy Terephthalic acid, ethoxytereph Le acid.

As the alicyclic dicarboxylic acid, trans-
1,4-cyclohexanedicarboxylic acid, cis-1,4-
Alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid and 1,3-cyclohexanedicarboxylic acid; alkyl-, alkoxy- or halogen-substituted alicyclic dicarboxylic acids such as trans-1,4- (1-methyl) cyclohexanedicarboxylic acid; Trans-1,4- (1-chloro) cyclohexanedicarboxylic acid and the like.

Examples of the aromatic diol include hydroquinone, resorcin, 4,4'-dihydroxydiphenyl,
4,4 "-dihydroxytriphenyl, 2,6-naphthalenediol, 4,4'-dihydroxydiphenyl ether, bis (4-hydroxyphenoxy) ethane, 3,
3'-dihydroxydiphenyl, 3,3'-dihydroxydiphenyl ether, 1,6-naphthalenediol,
2,2-bis (4-hydroxyphenyl) propane,
Aromatic diols such as 1,1-bis (4-hydroxyphenyl) methane; alkyl, alkoxy or halogen-substituted aromatic diols, for example, chlorohydroquinone, methylhydroquinone, 1-butylhydroquinone, phenylhydroquinone, methoxyhydroquinone, phenoxy Hydroquinone, 4-chlororesorcin, 4-methylresorcin and the like can be mentioned.

As the alicyclic diol, trans-1,1,
4-cyclohexanediol, cis-1,4-cyclohexanediol, trans-1,4-cyclohexanedimethanol, trans-1,3-cyclohexanediol, cis-1,2-cyclohexanediol, trans-1,3-cyclohexanedi Alicyclic diols such as methanol; alkyl, alkoxy or halogen-substituted alicyclic diols such as trans-1,4- (1-methyl) cyclohexanediol, trans-1,4-
(1-chloro) cyclohexanediol and the like.

Examples of the aliphatic diol include linear or branched aliphatic diols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, and neopentyl glycol.

As the aromatic hydroxycarboxylic acid, 4
-Hydroxybenzoic acid, 3-hydroxybenzoic acid, 6-
Aromatic hydroxycarboxylic acids such as hydroxy-2-naphthoic acid and 6-hydroxy-1-naphthoic acid; alkyl, alkoxy or halogen-substituted aromatic hydroxycarboxylic acids such as 3-methyl-4-hydroxybenzoic acid, 3 , 5-Dimethyl-4-hydroxybenzoic acid, 2,
6-dimethyl-4-hydroxybenzoic acid, 3-methoxy-4-hydroxybenzoic acid, 3,5-dimethoxy-4-
Hydroxybenzoic acid, 6-hydroxy-5-methyl-2
-Naphthoic acid, 6-hydroxy-5-methoxy-2-naphthoic acid, 3-chloro-4-hydroxybenzoic acid, 2,
3-dichloro-4-hydroxybenzoic acid, 3,5-dichloro-4-hydroxybenzoic acid, 2,5-dichloro-4
-Hydroxybenzoic acid, 3-bromo-4-hydroxybenzoic acid, 6-hydroxy-5-chloro-2-naphthoic acid, 6-hydroxy-7-chloro-2-naphthoic acid, 6
-Hydroxy-5,7-dichloro-2-naphthoic acid and the like.

As the aromatic mercaptocarboxylic acid, 4
-Mercaptobenzoic acid, 3-mercaptobenzoic acid, 6-
And mercapto-2-naphthoic acid and 7-mercapto-2-naphthoic acid.

As the aromatic dithiol, benzene-
1,4-dithiol, benzene-1,3-dithiol,
Naphthalene-2,6-dithiol, naphthalene-2,7
-Dithiol and the like.

As the aromatic mercaptophenol, 4
-Mercaptophenol, 3-mercaptophenol,
2-mercaptophenol and the like.

As the aromatic hydroxyamine and aromatic diamine, 4-aminophenol, N-methyl-4-aminophenol, 1,4-phenylenediamine, N-methyl-1,4-phenylenediamine, N, N ' -Dimethyl-1,4-phenylenediamine, 3-aminophenol, 3-methyl-4-aminophenol, 2-chloro-
4-aminophenol, 4-amino-1-naphthol,
4-amino-4'-hydroxydiphenyl, 4-amino-4'-hydroxydiphenyl ether, 4-amino-
4'-hydroxydiphenylmethane, 4-amino-4 '
-Hydroxydiphenyl sulfide, 4,4'-diaminophenyl sulfide (thiodianiline), 4,4'-
Diaminodiphenylsulfone, 2,5-diaminotoluene, 4,4'-ethylenedianiline, 4,4'-diaminodiphenoxyethane, 4,4'-diaminodiphenylmethane (methylenedianiline), 4,4'-diaminodiphenylether (Oxydianiline) and the like.

The above-mentioned polymers a) to h) composed of the above-mentioned respective constituents may have no birefringence upon melting depending on the constituents and the composition ratio and the sequence distribution in the polymer, but are used in the present invention. Polymers are limited to those having birefringence when melted among the above polymers.

The liquid crystalline polymer used in the present invention can be produced by a conventionally known method.

The wholly aromatic polymer suitably used in the present invention tends to be substantially insoluble in common solvents,
Therefore, it is not suitable for solution processing. However, these polymers can be easily processed by conventional melt processing methods. It should be noted that particularly preferred fully aromatic polymers are somewhat soluble in pentafluorophenol.

The liquid crystalline polymer used in the present invention may have an appropriate molecular weight as long as film formability and the like are not impaired. For example, suitable wholly aromatic polyesters usually have a weight average molecular weight of about 2,000 to 200,000, preferably about 10,000.
00 to 50,000, particularly preferably about 20,000 to 25,000.
Also, suitable wholly aromatic polyesteramides typically have a molecular weight of about 5,000 to 50,000, preferably about 10,000 to 30,000.
0, for example, 15,000 to 17,000. The measurement of molecular weight
It can be carried out by gel permeation chromatography as well as other standard methods without melt formation of the polymer, for example by quantifying end groups by infrared spectroscopy on compression molded films. The molecular weight can also be measured using a pentafluorophenol solution and using a light scattering method.

The above completely aromatic polyesteramide is
0.1% by weight in pentafluorophenol at a temperature of 60 ° C
At least about 2.0 dl / g when dissolved at a concentration
For example, logarithmic viscosity (IV) of about 2.0 to 10.0 dl / g
Is generally indicated.

Particularly preferred polyesters forming the anisotropic molten phase are 6-hydroxy-2-naphthoyl, 2,6
-Containing naphthalene partial units such as dihydroxynaphthalene and 2,6-dicarboxynaphthalene in an amount of about 10 mol% or more. Preferred polyesteramides are those containing repeating units of the naphthalene moiety and a moiety consisting of 4-aminophenol or 1,4-phenylenediamine. Specifically, it is as follows.

(A) a polyester consisting essentially of the following repeating units I and II:

Embedded image I

Embedded image II The polyester contains about 10-90 mol% of unit I and about 10-90 mol% of unit II. In one embodiment, unit I is about 65-85 mol% (eg, about 75 mol%)
Up to the amount. In other embodiments, Unit II has about 15
It is present in low amounts of 35 mol%, preferably about 20-30 mol%. At least a part of the hydrogen atoms bonded to the ring is substituted with a substituent selected from the group consisting of an alkoxy group having 1 to 4 carbon atoms, a halogen atom, a phenyl group, a substituted phenyl group, and combinations thereof. You may.

(B) a polyester consisting essentially of the following repeating units II, III and IV:

Embedded image II

Embedded image III

Embedded image IV The polyester contains about 30-70 mol% of unit II. The polyester preferably has units II of about 40
６０60 mol%, unit 20 is about 20-30 mol% and unit
Contains about 20-30 mol% of IV. At least a part of the hydrogen atoms bonded to the ring is substituted by a substituent selected from the group consisting of an alkoxy group having 1 to 4 carbon atoms, a halogen atom, a phenyl group, a substituted phenyl group, and a combination thereof. You may.

(C) a polyester consisting essentially of the following repeating units II, IV, V and VI:

Embedded image II

Embedded image IV

Embedded image V

Embedded image VI wherein R is methyl, chloro, bromo or a combination thereof and is a substituent for a hydrogen atom on the aromatic ring. It contains about 5 to 35 mol%, about 5 to 18 mol% of unit V and about 20 to 40 mol% of unit VI. The polyester preferably contains about 35-45 mol% of unit II, about 15-25 mol% of unit IV, about 10-15 mol% of unit V and about 25-35 mol% of unit VI. However,
The total molarity of units IV and V is substantially equal to the molarity of unit VI. Further, at least a part of the hydrogen atoms bonded to the ring is a group consisting of an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a halogen atom, a phenyl group, a substituted phenyl group, and a combination thereof. May be substituted by a substituent selected from The wholly aromatic polyester, when dissolved at a temperature of 60 ° C. in pentafluorophenol at a concentration of 0.3 W / V%, has at least 2.
A logarithmic viscosity of 0 dl / g, for example 2.0 to 10.0 dl / g is generally indicated.

(D) essentially the following repeating units I, II, VII
And VIII polyesters;

Embedded image I

Embedded image II

Embedded image A dioxyaryl unit represented by VII (wherein, Ar represents a divalent group containing at least one aromatic ring)

Embedded image A dicarboxyaryl unit of the formula VIII wherein Ar is as defined above, the polyester comprising about 20 to 40 mol% of unit I, more than 10 mol% of unit II and not more than about 50 mol%;
Is contained in an amount of more than 5 mol% and about 30 mol% or less, and unit VIII in an amount of more than 5 mol% and about 30 mol% or less. The polyester preferably has a unit I of about 20-30.
Mol%, for example, about 25 mol%;
Mole%, for example, about 35 mole%, the unit VII is about 15 to 2
5 mol%, for example about 20 mol%, and unit VIII of about 1
It contains 5 to 25 mol%, for example, about 20 mol%. Further, at least a part of the hydrogen atoms bonded to the ring is a group consisting of an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a halogen atom, a phenyl group, a substituted phenyl group, and a combination thereof. And may be substituted with a substituent selected from

The units VII and VIII comprise a divalent bond linking these units to other units on both sides in the polymer backbone.
Symmetric in the sense that they are symmetrically arranged on one or more aromatic rings (eg, when present on a naphthalene ring, they are para to each other or arranged on a diagonal ring) Is preferred. However, asymmetric units such as those derived from resorcinol and isophthalic acid can also be used.

Preferred dioxyaryl units VII are

Embedded image And a preferred dicarboxyaryl unit VIII is

Embedded image It is.

(E) essentially the following repeating units I, VII, VII
Polyester consisting of I;

Embedded image I

Embedded image VII (wherein Ar is as defined above)

Embedded image A dicarboxyaryl unit of the formula VIII (where Ar is as defined above) The polyester comprises about 10 to 90 mol% of unit I, 5 to 45 mol% of unit VII and 5 to 45 mol% of unit VIII.
In the amount of This polyester is preferably a unit
It contains about 20-80 mol% of I, about 10-40 mol% of unit VII and about 10-40 mol% of unit VIII. More preferably, the polyester has about 60-80 mole%
Of unit I, about 10 to 20 mol% of unit VII, and about 10
Contains ２０20 mol% of unit VIII. At least a part of the hydrogen atoms bonded to the ring includes an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a halogen atom,
It may be substituted with a substituent selected from the group consisting of a phenyl group, a substituted phenyl group and a combination thereof.

Preferred dioxyaryl units VII are

Embedded image And a preferred dicarboxyaryl unit VIII is

Embedded image It is.

(F) Polyesteramide consisting essentially of the following repeating units I, IX, X and VII

Embedded image I

Embedded image IX (wherein, A represents a divalent group containing at least one aromatic ring or a divalent trans-cyclohexane group)

Embedded image X (wherein, Ar is the same as above; Y is O, NH or NR,
Z means NH or NR, respectively, and R has 1 to 1 carbon atoms.
4 means an alkyl group or an aryl group)

Embedded image Dioxyaryl unit represented by VII (wherein Ar is as defined above) The polyesteramide comprises about 10 to 90 mol% of unit I, 5 to 45 mol% of unit IX, and 5 to 45 mol% of unit X. , And unit VII in an amount of about 0-40 mol%.
At least a part of the hydrogen atoms bonded to the ring is selected from the group consisting of an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a halogen atom, a phenyl group, a substituted phenyl group, and a combination thereof. It may be substituted by the selected substituent.

Preferred dicarboxyaryl units IX are

Embedded image And the preferred unit X is

Embedded image Or

Embedded image And preferred dioxyaryl units VII are

Embedded image It is.

Further, in the polymer forming the anisotropic molten phase of the present invention, a part of one polymer chain is constituted by a segment of the polymer forming the anisotropic molten phase, and the remaining part is anisotropic. Also included are polymers composed of thermoplastic resin segments that do not form a fusible melt phase.

The above-mentioned liquid crystalline polymer has not only excellent gas barrier properties at room temperature but also excellent heat resistance, and thus has no temperature dependence of gas barrier properties. That is, even when subjected to high temperature, for example, retort sterilization, the gas barrier property and the water vapor barrier property do not decrease. The heat distortion temperature of the liquid crystalline polymer is usually 80 to 400 ° C, preferably 120 to 3 ° C.
It is about 50 ° C. Particularly, a liquid crystalline polymer having a heat distortion temperature of 150 to 250 ° C. is preferable because of excellent film formability. In addition,
The oxygen gas transmission rate and the water vapor transmission rate of the liquid crystalline polymer are usually 1.0 cc / m 2 · 25 μm · 24 hours · atmospheric pressure or less.

The liquid crystalline polymer is contained in the liquid crystalline polymer layer in an amount of at least 50% by weight, preferably 75% by weight or more.

The melt-processable polymer composition for forming an anisotropic melt phase used in the present invention includes other polymers forming an anisotropic melt phase, thermoplastic resins not forming an anisotropic melt phase, It may contain at least one of a thermosetting resin, a low molecular organic compound, and an inorganic substance. The polymer forming the anisotropic molten phase in the composition and other components may be thermodynamically compatible.

Examples of the above-mentioned thermoplastic resin include polyethylene, polypropylene, polybutylene, polybutadiene, polyisoprene, polyvinyl acetate, ethylene-
Vinyl acetate copolymer, ethylene-acrylate copolymer, ethylene-methacrylate copolymer, ionomer, polyvinyl chloride, polyvinylidene chloride, polystyrene, acrylic resin, ABS resin, AS resin,
BS resin, polyurethane, silicone resin, fluororesin, polyacetal, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, aromatic polyester, polyamide, polyacrylonitrile, polyvinyl alcohol, polyvinyl ether, polyetherimide, polyamideimide, polyetheretherimide, poly Ether ether ketone, polyether sulfone, polysulfone, polyphenylene sulfide,
And polyphenylene oxide.

The above-mentioned thermosetting resins include, for example, phenol resins, epoxy resins, melamine resins, urea resins, unsaturated polyester resins, diallyl phthalate resins, alkyd resins and the like.

Examples of the low-molecular-weight organic compound include substances usually added to thermoplastic resins and thermosetting resins, such as weathering and light-resistant stabilizers such as plasticizers, antioxidants and ultraviolet absorbers, and electrification. Used as an inhibitor, a flame retardant, a coloring agent such as a dye or a pigment, a foaming agent, a divinyl compound, a crosslinking agent such as a peroxide or a vulcanizing agent, and a lubricant for improving fluidity and mold release properties. Low molecular weight organic compounds.

Further, as the above-mentioned inorganic substances, for example,
Substances commonly added to thermoplastics and thermosets,
That is, glass fibers, carbon fibers, metal fibers, ceramic fibers, boron fibers, general inorganic fibers such as asbestos, calcium carbonate, highly dispersible silica, alumina, aluminum hydroxide, talc powder, mica, glass flakes, glass beads, Examples include powdered substances such as quartz powder, silica sand, various metal powders, carbon black, barium sulfate, calcined gypsum and the like, inorganic compounds such as silicon carbonate, boron nitrite and silicon nitride, whiskers and metal whiskers.

The thickness of the liquid crystal polymer layer containing the above liquid crystal polymer is not particularly limited, but is usually from 1 to 500.
μm, preferably 5-250 μm, more preferably 1 μm
It is about 0 to 150 μm.

In the multilayer film of the present invention, a polyalkylene terephthalate layer is laminated on one surface of the liquid crystalline polymer layer via an adhesive layer, and an olefin polymer layer is laminated on the other surface via an adhesive layer. I have.

Examples of the polyalkylene terephthalate include those having an alkylene group having about 2 to 6 carbon atoms,
Those having a cycloalkylene group or an ether group in part of the alkylene group, particularly polyethylene terephthalate,
Polyalkylene terephthalate having high heat resistance, for example, so-called PET-G in which a part of ethylene glycol is substituted by 1,4-cyclohexanedimethanol, diethylene glycol, or the like, or polybutylene terephthalate is preferable.
The polyalkylene terephthalate having high heat resistance can be easily coextruded with the liquid crystalline polymer.

A plurality of the same or different polyalkylene terephthalate layers may be laminated. Further, by laminating the liquid crystalline polymer layer and the polyalkylene terephthalate layer, gas barrier properties such as oxygen gas barrier properties can be further enhanced, and heat resistance is excellent.

Examples of the olefin polymer in the olefin polymer layer include polyethylene, polypropylene, ethylene-propylene copolymer, poly-4-methylpentene-1, ionomer, ethylene-ethyl acrylate copolymer, ethylene-acetic acid. Examples include vinyl copolymers. Among these olefin-based polymers, polyethylene, especially high-density polyethylene, medium-density polyethylene, polypropylene and ethylene-propylene copolymer,
Particularly, an ethylene-propylene copolymer having a melting point of 145 to 160 ° C is preferable. Note that a plurality of the same or different olefin-based polymer layers may be laminated. Further, by laminating the liquid crystal polymer layer and the olefin polymer layer, the water vapor barrier property can be further enhanced, and the heat sealing property can be secured by the olefin polymer layer. Therefore, a bag can be easily formed by pillow packaging, a four-sided sheet, or the like, and its use can be expanded.

The thickness of the polyalkylene terephthalate layer and the olefin polymer layer is not particularly limited, but is usually about 1 to 50 μm.

The adhesive layer is not particularly limited as long as it contains an epoxidized diene-based block copolymer and exhibits adhesiveness to a liquid crystal polymer layer, a polyalkylene terephthalate layer and an olefin-based polymer layer. As an example, containing an epoxidized diene-based block copolymer, polyurethane, butadiene-acrylonitrile copolymer and other general-purpose film adhesives, and urethane prepolymers, even anchor coating agents such as alkyl titanates Good.

The diene block copolymer in the present invention refers to a block copolymer comprising a polymer block mainly composed of a vinyl aromatic compound and a polymer block mainly composed of a conjugated diene compound. The copolymerization ratio (on a molar basis) of the group III compound and the conjugated diene compound is from
70/30, and particularly preferably a copolymerization ratio of 10/90 to 60/40. The block copolymer used in the present invention has a number average molecular weight of 5,000 to 600,000, preferably 10,000 to 500,000, and has a molecular weight distribution [weight average molecular weight (Mw) and number average molecular weight]. (M
(Mw / Mn)] is 10 or less. The molecular structure of the block polymer may be linear, branched, radial, or any combination thereof.

For example, XYX, YXYX,
It is a vinyl aromatic compound (X) block-conjugated diene compound (Y) block copolymer having a structure such as (XY-) 4Si or XYXYX. Further, the unsaturated bond of the conjugated diene compound of the diene block copolymer may be partially hydrogenated.

Examples of the vinyl aromatic compound constituting the epoxy-modified diene-based block polymer include styrene and
α-methylstyrene, vinyltoluene, p-tertiary butylstyrene, divinylbenzene, p-methylstyrene,
One or two of 1,1-diphenylstyrene and the like
More than one species can be selected, among which styrene is preferred. Also,
Examples of the conjugated diene compound include butadiene, isoprene, 1,3-pentadiene, and 2,3-dimethyl-
1,3-butadiene, piperylene, 3-butyl-1,3
One or more of octadiene, phenyl-1,3-butadiene and the like are selected, and among them, butadiene, isoprene and a combination thereof are preferred.

As the method for producing the block polymer used in the present invention, any production method having the above-mentioned structure can be used. For example, Japanese Patent Publication No. 40-2
3798, JP-B-47-3252, JP-B-48-2
No. 423, Japanese Patent Application No. 49-105970, Japanese Patent Application No. 50-
No. 27094, JP-B-46-32415, JP-A-59-1984
No. 166518, JP-B-49-36957, JP-B-43-17979, JP-B-46-32415, JP-B-56-28925 and the like, using a lithium catalyst or the like. A vinyl aromatic compound-conjugated diene compound block copolymer can be synthesized in a solvent. Further, Japanese Patent Publication No. 42-8704, Japanese Patent Publication No. 43-6636, or
According to the method described in JP-A-133203, the partially hydrogenated block copolymer to be used in the present invention can be synthesized by hydrogenation in an inert solvent in the presence of a hydrogenation catalyst. In the present invention, the epoxidized diene-based block copolymer used in the present invention is obtained by epoxidizing the above-mentioned diene block copolymer.

The epoxidized diene-based block copolymer in the present invention can be obtained by reacting the above-mentioned block copolymer with an epoxidizing agent such as a hydroperoxide or a peracid in an inert solvent. Examples of peracids include formic acid, peracetic acid, and perbenzoic acid. In the case of hydroperoxides, a catalytic effect can be obtained by using a mixture of tungstic acid and caustic soda with hydrogen peroxide, an organic acid with hydrogen peroxide, or molybdenum hexacarbonyl with tertiary butyl hydroperoxide. .

There is no strict limit on the amount of epoxidizing agent,
The optimal amount in each case will depend on variables such as the particular epoxidizing agent used, the degree of epoxidation desired, the particular block copolymer used, and the like.

The obtained epoxidized diene copolymer is isolated by an appropriate method, for example, a method of precipitating with a poor solvent, a method of pouring the polymer into hot water with stirring and distilling off the solvent, or a method of directly removing the solvent. It can be performed by a desolvation method or the like.

At least one adhesive layer between the films may be formed, and a plurality of adhesive layers may be formed as necessary. The thickness of the adhesive layer is not particularly limited as long as the adhesiveness is not impaired, but a sufficient adhesiveness can be generally secured at about 0.1 to 50 μm.

The epoxidized diene block copolymer is contained in the adhesive layer in an amount of 10% by weight or more.

The above-mentioned polyalkylene terephthalate layer, olefin-based polymer layer and adhesive layer containing the above-mentioned epoxidized diene-based block copolymer are made of the thermoplastic resin, low molecular weight organic compound, rosin / rosin derivative, terpene It may contain a tackifier such as a phenol resin or a petroleum resin, an inorganic material such as a polyolefin or paraffin wax, or the like.

The multilayer film of the present invention is not limited to a conventional method such as a dry laminating method and an extrusion laminating method, but also includes a multi-layer molding method coextruded with polyalkylene terephthalate since the liquid crystalline polymer has a high melting point. Can be formed by a method combining. As the co-extrusion multi-layer molding method, any of a multi-manifold method in which the layers are merged in a die and a feed block method can be adopted. At the time of laminating, a corona discharge treatment, a sputtering treatment, a high-frequency treatment, a flame treatment, a chromic acid treatment, a solvent etching treatment, an undercoat treatment, or a combination of these surface treatments may be performed.

Further, the multilayer film of the present invention may be uniaxially or biaxially stretched to an appropriate magnification by stretching means such as roll stretching, belt stretching, tenter stretching, and tube stretching. Note that at least one of the liquid crystal polymer layer, the polyalkylene terephthalate layer, and the olefin-based polymer layer may be stretched.

The multilayer film of the present invention can be used as a film for individual packaging, interior packaging, exterior packaging, and bag making of various packages. For example, since it is excellent in oxygen gas barrier properties and water vapor barrier properties, in addition to conventional food packaging films, packaging materials for oily cooking materials, packaging materials for medicines, packaging materials for cosmetics, fragrance-retaining packaging materials for aromatic substances, etc. Can be used as Further, since it shows resistance even at high temperatures, it is particularly suitable as a field requiring gas barrier properties at high temperatures, for example, food packaging materials such as retort foods, microwave foods and the like.

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DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to embodiments.

(Preparation of Epoxidized Diene Block Copolymer) Preparation Example 1 A polystyrene-polybutadiene-polystyrene block copolymer a [styrene / butadiene] was placed in a jacketed reactor equipped with a stirrer, a reflux condenser, and a thermometer. (Weight ratio = 40/60) 300 g and ethyl acetate 1500 g were charged and dissolved. Then, 165 g of a 30 wt% solution of peracetic acid in ethyl acetate was continuously dropped, and an epoxidation reaction was carried out at 40 ° C. for 3 hours with stirring. The reaction solution was returned to room temperature, taken out of the reactor, and a large amount of methanol was added to precipitate a polymer. The polymer was separated by filtration, washed with water, and dried to obtain an epoxy-modified polymer. The obtained epoxidized diene-based block copolymer is designated as epoxidized diene-based block copolymer A (epoxy equivalent of the polymer is 490).

Preparation Example 2 A polystyrene-polybutadiene-polystyrene block copolymer [styrene / butadiene weight ratio = 20/80] was placed in a jacketed reactor equipped with a stirrer and a thermometer.
300 g and cyclohexane 3000 g are charged and dissolved,
A temperature of 60 ° C. and di-P-tolylbis (1-
40 ml of a cyclopentadienyl) titanium / cyclohexane solution (concentration 1 mmol / l);
n-butyllithium solution (concentration 5 mmol / l)
8 ml and a mixture obtained by mixing at 0 ° C. under a hydrogen pressure of 2.0 kg / cm 2, and adding a hydrogen partial pressure of 2.5 kg / cm 2
For 60 minutes. The solvent was removed from the obtained partially hydrogenated polymer solution by drying under reduced pressure (the hydrogenation ratio of the entire butadiene portion was 80%). 300 g of this partially hydrogenated polymer and 1500 g of cyclohexane were charged and dissolved. Then, 200 g of a 30% by weight solution of peracetic acid in ethyl acetate was dropped continuously.
The epoxidation reaction was performed at 40 ° C. for 3 hours with stirring. The reaction solution was returned to room temperature, taken out of the reactor, and a large amount of methanol was added to precipitate a polymer. The polymer was separated by filtration, washed with water, and dried to obtain an epoxy-modified polymer. The obtained epoxidized diene-based block copolymer is referred to as polymer B (epoxy equivalent of the polymer is 460).

Preparation Example 3 A block copolymer of polystyrene-polyisoprene-polystyrene [styrene / isoprene weight ratio = 30/70] was placed in a jacketed reactor equipped with a stirrer and a thermometer.
300 g and 2500 g of cyclohexane are charged and dissolved,
Add nickel catalyst as hydrogenation catalyst, hydrogen partial pressure 15kg
The reaction was carried out at 150 ° C./cm 2 for 3 hours. The solvent was removed from the obtained partially hydrogenated polymer solution by drying under reduced pressure (85% hydrogenation ratio of the whole butadiene portion). 300 g of this partially hydrogenated polymer and 1500 g of cyclohexane were charged and dissolved. Then, a 30% by weight solution of peracetic acid in ethyl acetate 1
50 g was continuously dropped, and an epoxidation reaction was performed at 40 ° C. for 3 hours with stirring. The reaction solution was returned to room temperature, taken out of the reactor, and a large amount of methanol was added to precipitate a polymer. The polymer was separated by filtration, washed with water, and dried to obtain an epoxy-modified polymer. The obtained epoxidized diene-based block copolymer is referred to as polymer C (epoxy equivalent of the polymer is 750).

Example 1 Polybutylene terephthalate (Polyplastics Co., Ltd.)
(Intrinsic viscosity 1.0 dl / g, measured in orthochlorophenol at a temperature of 25 ° C.): (PBT), epoxidized diene-based block copolymer A: (a), composed of the above repeating units I and II Liquid crystalline polymer composed of polyester (A) (manufactured by Polyplastics, trade name Vectra A900):
(b), maleic anhydride-modified ethylene-ethyl acrylate copolymer (trade name: Bondyne T, manufactured by Sumitomo Chemical Co., Ltd.)
X8030): (c), polypropylene (trade name: Noblen FS2011D, manufactured by Sumitomo Chemical Co., Ltd.): (PP)
Are supplied to a feed block type multilayer molding apparatus, and are co-extruded into 6 layers to obtain (PBT) / (a) / (b) / (a) /
(c) / (PP) = 20/10/30/10/10/10/20 μm
Was produced.

Example 2 Epoxidized diene block copolymer A as component (a)
A six-layer film was produced in the same manner as in Example 1 except that epoxidized diene-based block copolymer B was used instead of.

Example 3 (a) Epoxidized diene block copolymer A as a component
A six-layer film was produced in the same manner as in Example 1 except that epoxidized diene-based block copolymer C was used instead of.

Comparative Example 1 Polypropylene (manufactured by Sumitomo Chemical Co., Ltd., trade name: Noblen FL6315G): (PP), maleic anhydride-modified polypropylene (manufactured by Mitsubishi Yuka Co., Ltd., Modec P310)
K): (f), saponified ethylene-vinyl acetate copolymer (manufactured by Solvay Co., Ltd., trade name: Clarane L6): Coextruded into 5 layers in the same manner as in Example 1 using (g), and (PP) ) /
(f) / (g) / (f) / (PP) = 25/10/30/10/2
A 5 μm multilayer film was produced.

Comparative Example 2 Polypropylene (PP) and ethylene-vinyl acetate copolymer of Comparative Example 1 (trade name: Evaflex P1905, manufactured by DuPont Mitsui): (EVA), polyvinylidene chloride copolymer (chlorinated) 90 parts by weight or more of vinylidene and 10 parts by weight or less of methyl acrylate) 5 parts by weight of epoxy resin, 5 parts by weight of dibutyl sebacate as a plasticizer, and 0.3 parts by weight of stearic acid as a lubricant based on 100 parts by weight Resin composition consisting of: (PVDC), co-extruded into 5 layers in the same manner as in Example 1, and (PP) / (EVA) / (PVDC) / (EV
A) / (PP) = 25/10/30/10/25 μm multilayer film was prepared.

Comparative Example 3 Polybutylene terephthalate (Polyplastics Co., Ltd.)
Intrinsic viscosity 1.0 dl / g measured in orthochlorophenol at a temperature of 25 ° C.): (PBT), glycidyl-modified ethylene-vinyl acetate copolymer (manufactured by Sumitomo Chemical Co., Ltd.)
Brand name Bond First 7B): (a), the repeating unit I
, A liquid crystalline polymer comprising polyester (A) composed of II (manufactured by Polyplastics Co., Ltd., trade name Vectra A
900): (b), maleic anhydride-modified ethylene-ethyl acrylate copolymer (manufactured by Sumitomo Chemical Co., Ltd., trade name: Bondine TX8030): (c), polypropylene (manufactured by Sumitomo Chemical Co., Ltd., trade name) Noblen FS2011
D): Each of (PP) is supplied to a feed block type multilayer molding apparatus and co-extruded into 6 layers, and (PBT) / (a) /
(b) / (a) / (c) / (PP) = 20/10/30/10/1
A 0/20 μm multilayer film was produced.

Then, the oxygen gas permeability, the water vapor permeability and the oxygen gas permeability after the retort sterilization treatment were examined by the following test methods.

Oxygen gas permeability Under a condition of a temperature of 23 ° C. and a relative humidity of 60%, a nitrogen gas 98
%, Hydrogen gas 2%, and AST
It was measured by the isobaric method according to MD-3985-81.

Water vapor permeability Measured under the conditions of a temperature of 25 ° C. and a relative humidity of 90% using air as a carrier gas and an infrared sensor according to ASTM F-372-73.

Oxygen gas permeability after retort sterilization treatment Immersion in pressurized hot water at a temperature of 120 ° C. for 30 minutes,
The measurement was carried out under the conditions of a temperature of 20 ° C. and a relative humidity of 40% according to the method for measuring the oxygen gas permeability.

Table 1 shows the results.

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[Table 1]

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As described above, according to the multilayer film of the present invention, the polyalkylene terephthalate layer and the olefin-based polymer layer are respectively epoxidized with the epoxidized diene layer via the liquid crystalline polymer layer containing the thermotropic liquid crystalline polymer. Since it is laminated with an adhesive layer containing a system block copolymer, it has excellent oxygen gas barrier properties and moisture proof properties even when exposed to high temperature and high humidity, and also has excellent heat sealing properties.

Claims (2)

[Claims] 1. A polyalkylene terephthalate layer and an olefin-based polymer layer each being laminated with an adhesive layer containing an epoxidized diene-based block copolymer via a liquid-crystalline polymer layer containing a thermotropic liquid-crystalline polymer. A multilayer film. 2. An epoxidized diene-based block copolymer is composed of a polymer block mainly composed of vinyl aromatic in the same molecule and a polymer block mainly composed of a conjugated diene compound partially containing epoxy. 2. The multilayer film according to claim 1, comprising a polymer block mainly composed of a hydrogenated conjugated diene compound containing epoxy.