JPH02253951A - Multilayer film - Google Patents

Abstract

PURPOSE:To obtain a multilayer film excellent in heat resistance, having no polyolefin smell, holding excellent gas barrier properties and adaptable to various uses by laminating a polyalkylene terephthalate layer to both surfaces of a liquid-crystalline polymer layer containing a thermotropic liquid-crystalline polymer through adhesive layer. CONSTITUTION:A multilayer film is formed by laminating a polyalkylene terephthalate layer to both surfaces of a liquid-crystalline polymer layer through an adhesive layer. As polyalkylene terephthalate, polyethylene terephthalate or highly heat-resistant polyalkylene terephthalate, for example, PET-G is especially pref. A plurality of polyalkylene terephthalate layers of the same kind or different kinds may be laminated. By laminating the liquid-crystalline polymer and the polyalkylene terephthalate layer, gas barrier properties such as oxygen barrier properties can be enhanced still more and heat resistance is made excellent. The adhesive pref. contains modified polyolefin or polyester.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a multilayer film that includes a liquid crystalline polymer layer as a component and has excellent heat resistance, gas barrier properties, and the like.

[Prior art and problems to be solved by the invention] Conventionally, as packaging films, polypropylene films have been used on both sides of stretched films such as polypropylene and polyethylene terephthalate, and films made of saponified ethylene-vinyl acetate copolymers. Composite films laminated via adhesive layers containing acid-modified polypropylene and the like are widely used. However, polypropylene films do not have sufficient oxygen gas barrier properties, and polyethylene terephthalate films do not have sufficient moisture resistance, that is, water vapor barrier properties. Further, in the above composite film, the oxygen gas barrier properties of the film made of a saponified ethylene-vinyl acetate copolymer are significantly reduced due to moisture absorption. For example, after retort sterilization, the oxygen gas barrier properties of coal are about 10 to 40 times lower.

Therefore, it is difficult to preserve foods and the like for a long period of time.

Furthermore, the above-mentioned composite film not only does not have sufficient heat resistance due to its constituent polymers, but also produces an undesirable polyolefin odor especially when heated.

A composite film has also been proposed in which a polypropylene film is laminated on both sides of a polyvinylidene chloride film with a layer made of ethylene-vinyl acetate copolymer interposed therebetween. According to this composite film, the polyvinylidene chloride film can ensure oxygen gas barrier properties, and the polypropylene film can ensure water vapor barrier properties. However, in order to impart moldability, plasticizers and stabilizers are usually added to polyvinylidene chloride, resulting in a decrease in gas barrier properties. Furthermore, since polyvinylidene chloride has a low glass transition temperature, it becomes plasticized as the temperature rises, resulting in a decrease in gas barrier properties at high temperatures as described above, and insufficient heat resistance due to the constituent polymers.

On the other hand, polybutylene terephthalate and the like are known as films with excellent heat resistance. Therefore, it is also conceivable to laminate this film and the above polyvinylidene chloride film. However, since the melting point and decomposition temperature of polyvinylidene chloride are close to each other and it decomposes at about 180 to 200°C, it is difficult to form a laminated film by coextrusion with polybutylene lentil, tallate, etc., which have excellent heat resistance. .

Therefore, an object of the present invention is to provide a multilayer film that has excellent heat resistance, has no polyolefin odor even when exposed to high temperature and high humidity, maintains excellent gas barrier properties, and can be used for various purposes.

[Structure of the Invention] The present inventors have discovered that a thermotropic liquid crystalline polymer exhibits high gas barrier properties, and have completed the present invention as a result of intensive research into film formation thereof. That is, the present invention uses a multilayer film in which polyalkylene terephthalate layers are laminated on both sides of a liquid crystalline polymer layer containing a thermotropic liquid crystalline polymer via an adhesive layer.
This solves the above problem. Note that the adhesive layer preferably contains modified polyolefin or polyester.

As used herein, the term "liquid crystalline polymer" refers to a thermotropic liquid crystalline polymer and a composition thereof, which become softened and fluidized by heating, become moldable, and exhibit an anisotropic melt phase having birefringence when melted.

Furthermore, the term "film" is used to include all relatively thin, substantially flat structures that are sometimes referred to as sheets or the like in the technical field.

Examples of the above-mentioned liquid crystalline polymers include polymers consisting of the constituent components listed in F and the like.

(1) One or more aromatic dicarboxylic acids and alicyclic dicarboxylic acids (2) One or more aromatic diols, alicyclic diols, and aliphatic diols (3) One or more aromatic hydroxycarboxylic acids or two or more types (4) one or two or more aromatic thiol carboxylic acids (5) one or two or more aromatic dithiols, aromatic thiol phenols (B) one or two aromatic hydroxyamines, aromatic diamines More than a species.

Liquid crystalline polymers consisting of the above-mentioned components include: i) polyester consisting of constituent components (1) and (2); 1) polyester consisting of constituent component (3);
1), (2) and 3), iv) a polythiol ester consisting of component (4),
V) Polythiol ester consisting of constituent components (1) and (5), Vl) Polythiol ester consisting of constituent components (1), (4) and (5), wit) Constituent components (1) and (3) and (5) Polyesteramide consisting of vll, 1) Constituent components (1), (2), (3) and (
5) is selected as a combination of polyesteramide, etc. consisting of.

Although not included in the above combination of components, such liquid crystalline polymers include aromatic polyazomethine,
Specific examples include trilow (2-methyl-1,4-phenylenenitrilomethylidine-1,4-phenylenemethylidine) for poly, and trilow (2-methyl-1,4-phenylenenitrilomethylidine-1,4-phenylene) for poly. methylidine), and poly(trilow-2-chloro-1,4-phenylenenitrilomethylidine-1,4-phenylenemethylidine).

Further, although not included in the scope of the above-mentioned component combinations, such liquid crystalline polymers include polyester carbonate. This polymer essentially contains 4-oxybenzoyl units, dioxyphenyl units, dioxycarbonyl units and terephthaloyl units.

Examples of the aromatic dicarboxylic acids include terephthalic acid, 4.
4'-diphenyldicarboxylic acid, 4°4'-triphenyldicarboxylic acid, 2,6-naphthalene dicarboxylic acid, diphenyl ether-4°4'-dicarboxylic acid, diphenoxyethane-4°4'-dicarboxylic acid1. Diphenoxybutane-4゜4'-dicarboxylic acid, diphenylethane-
4゜4'-dicarboxylic acid, isophthalic acid, diphenylether-3,3'-dicarboxylic acid, diphenoxyethane-3,3'-dicarboxylic acid, diphenylethane-3,3
Aromatic dicarboxylic acids such as '-dicarboxylic acid, naphthalene-1,6-dicarboxylic acid; alkyl, alkoxy or halogen substituted aromatic dicarboxylic acids, such as chloroterephthalic acid, dichloroterephthalic acid, bromoterephthalic acid, methyl terephthalate, acid, dimethyl terephthalic acid, ethyl terephthalic acid, methoxyterephthalic acid, ethoxyterephthalic acid, and the like.

Examples of alicyclic dicarboxylic acids include alicyclic dicarboxylic acids such as trans-1゜4-cyclohexanedicarboxylic acid, cis-1,4-cyclohexanedicarboxylic acid, and 1,3-cyclohexanedicarboxylic acid; alkyl alicyclic dicarboxylic acids; , alkoxy or halogen substituted products, such as trans-1,4-(1-methyl)cyclohexanedicarboxylic acid, trans-1,4-(1-chloro)cyclohexanedicarboxylic acid, and the like.

Aromatic diols include hydroquinone, resorcinol, 4.4'-dihydroxydiphenyl, 4.41-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, 1.1-
Aromatic diols such as bis(4-hydroxyphenyl)methane; alkyl, alkoxy or halogen substituted aromatic diols, such as chlorohydroquinone, methylhydroquinone, 1-butylhydroquinone, phenylhydroquinone, methoxyhydroquinone, phenoxyhydroquinone, 4- Examples include chlororesorcin and 4-methylresorcin.

Examples of alicyclic diols include trans-1,4-cyclohexanediol, cis-1,4-cyclohexanediol, trans-1,4-cyclohexane dimetatool,
trans-1,3-cyclohexanediol, cis-1
, 2-cyclohexanediol, trans-1,3-cyclohexane dimetatool; alkyl, alkoxy or halogen substituted alicyclic diols, such as trans-1,4-(1-methyl)cyclohexane diol, trans-1,4(1-chloro)cyclohexanediol, and the like.

As the aliphatic diol, ethylene glycol, 1.3
- Straight-chain or branched aliphatic diols such as propanediol, 1,4-butanediol, and neopentyl glycol are mentioned.

Examples of aromatic hydroxycarboxylic acids include 4-hydroxybenzoic acid, 3-hydroxybenzoic acid, and 6-hydroxybenzoic acid.
Aromatic hydroxycarboxylic acids such as 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.

Examples of aromatic mercaptocarboxylic acids include 4-mercaptobenzoic acid, 3-mercaptobenzoic acid, 6-mercapto-2-naphthoic acid, and 7-mercapto-2-naphthoic acid.

Aromatic dithiols include benzene-1,4-dithiol, benzene-1,3-dithiol, naphthalene-2
, 6-dithiol, naphthalene-2,7-dithiol, and the like.

Examples of aromatic mercaptophenol include 4-mercaptophenol, 3-mercaptophenol, 2-mercaptophenol, and the like.

As aromatic hydroxyamine and aromatic diamine, 4
-aminophenol, N-methyl-4-aminophenol, 1,4-phenylenediamine, N-methyl-1,4
-phenylenediamine, N'1N'-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 (thiosif'niline), 4,4'-diaminodiphenylsulfoni /, 2.5-diaminotoluene, 4.4'-ethylene dianiline, 4.4'-diaminodiphenoxyethane, 4.4'-diaminodiphenylmethane (methylene dianiline), 4.4'-diaminodiphenyl ether (oxy) dianiline), etc.

The polymers 1) to vil consisting of the above constituent components
, i), depending on the constituent components, the composition ratio in the polymer, and the sequence distribution, there are some that do not have birefringence when melted, but the polymers used in the present invention are those that have birefringence when melted among the above polymers. limited to.

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

Fully aromatic polymers preferably used in the present invention tend to be substantially insoluble in common solvents and are therefore unsuitable for solution processing. However, these polymers can be processed into containers 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 within a range that does not impair film-forming properties and the like. for example,
Suitable fully aromatic polyesters usually have a weight average molecular weight of about 2,000 to 200. ．． 000, preferably about 1
0,000 to 50,000, particularly preferably about 20.0
00 to 25,000. Suitable fully aromatic polyesteramides also typically have a molecular weight of about 5.000 to 50.
,000, preferably about io,ooo to 30,000,
For example, it is 15,000 to 17,000. Molecular weight measurements can be performed by gel permeation chromatography as well as other standard measurements that do not involve melt formation of polymers, such as quantification of end groups by infrared spectroscopy on compression molded films. The molecular weight can also be measured using a light scattering method using a pentafluorophenol solution.

The fully aromatic polyester amide described above has at least about a OdJ/g, for example about 2.
It generally indicates a logarithmic viscosity (1, V,) of 0 to 10, Od J/g.

Particularly preferred polyesters forming an anisotropic melt phase are:
It contains naphthalene moieties such as 6-hydroxy-2-naphthoyl, 2.6-dihydroxynaphthalene, and 2.6-dicarboxynaphthalene in an amount of about 10 mole percent or more. Preferred polynisderamides are those containing repeating units of the above naphthalene moiety and a moiety consisting of 4-aminophenol or 1,4-phenylenediamine.

Specifically, the details are as follows.

(^) A polyester consisting essentially of the following repeating units I and (2); This polyester contains about 10 to 90 mol% of units I and about 10 to 90 mol% of units (2).

- In embodiments, the unit I is about 65 to 85 mol% (e.g.
up to an amount of about 75 mole %). In other aspects,
The unit ■ is about 15 to 35 mol%, preferably about 20 to 30
Present in amounts as low as mole %. In addition, at least a portion of the hydrogen atoms bonded to the ring are substituted with a substituent selected from the group consisting of an alkoxy group having 1 to 4 carbon atoms, a /Xrogen atom, a phenyl group, a substituted phenyl group, and a combination thereof. may have been done.

(B) This polyester contains about 30 to 70 mole percent of units (B) consisting essentially of the following repeating units (1), (2), and (2). This polyester preferably has about 40 to 60 units of
mol%, unit ■ is about 20 to 30 mol% and unit ■ is about 2
Contains 0 to 30 mol%. In addition, at least a part of the hydrogen atoms bonded to the ring is an alkoxy group having 1 to 4 carbon atoms,
It may be substituted with a substituent selected from the group consisting of a halogen atom, a phenyl group, a substituted phenyl group, and a combination thereof.

(C) A polyester consisting essentially of the following repeating units ■, ■, ■, and ■; This polyester contains about 20 to 60 mol % of the unit (2), about 5 to 35 mol % of the unit (2), about 5 to 18 mol % of the unit (2), and about 20 to 40 mol % of the unit (2). This polyester preferably contains about 35 to 45 mol % of units (2), about 15 to 25 mol % of units (2), about 10 to 15 mol % of units (V), and about 25 to 35 mol % of units (2). however,
The total molar concentration of units (2) and V is substantially equal to the molar concentration of units (2). Furthermore, at least some of the hydrogen atoms bonded to the ring are a group consisting of an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a balogen atom, a phenyl group, a substituted phenyl group, and a combination thereof. may be substituted with a substituent selected from. This fully aromatic polyester exhibits zero conversion to pentafluorophenol at a temperature of 60°C.
．． When dissolved at a concentration of 3 W/V%, at least 2. O
dJ/g, for example 2.0-10. Logarithmic viscosity in OdJ/g is generally indicated.

(D) Polyester consisting essentially of the following repeating units ■, ■, ■ and ■: General formula +0-Ar-0+ ■ (wherein A' means a divalent group containing at least one aromatic ring) ) (wherein Ar is the same as above) This polyester contains about 20 to 40 mol% of units I, more than 10 mol% of units The polyester preferably contains the unit 1 in an amount of more than 5 mol % but not more than about 30 mol %, and the unit 2 in an amount of more than 5 mol % and not more than about 30 mol %. About 20 to 30 mol%, e.g., about 25 mol%, about 25 to 40 mol%, e.g., about 35 mol%, of the unit ■, about 15 to 25 mol%, e.g., about 20 mol%, of the unit ■ About 15-25
It contains about 20 mol%, for example, about 20 mol%.

In addition, at least some of the hydrogen atoms bonded to the ring are
It may be substituted with a substituent 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.

Units ■ and ■ have a symmetrical arrangement on one or more aromatic rings in which the divalent bonds connecting these units to other units on both sides within the polymer main chain are arranged symmetrically (for example, naphthalene). When they are present on a ring, they are preferably symmetrical in the sense that they are disposed apart from each other or on a diagonal ring. However, asymmetric units such as those derived from resorcinol and isophthalic acid can also be used.

The preferred dioxyaryl unit (2) is and the preferred dicarboxyaryl unit (2) is.

(E) Polyester consisting essentially of the following repeating units 11 (11) and (1); Contains mol% of dioxyaryl units represented by the general formula +0-Ar-0+ (2) (wherein Ar is the same as above). More preferably, the polyester comprises about 60 to 80 mole% units, about 10 to 20 mole%
, and about 10 to 20 mol % of units (■). In addition, at least some of the hydrogen atoms bonded to the ring are
It may be substituted with a substituent 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.

A preferred dioxyaryl unit (2) is a dicarboxyaryl unit represented by (in the formula, A' is the same as above). This polyester contains about 10 to 90 mol% of the unit I, 5 to 45 mol% of the unit (2), and the unit (2). The polyester preferably contains about 20 to 80 mole percent of units I, about 10 to 40 mole percent of units (2), and about 10 to 4 degrees of units (2), preferably The dicarboxyaryl unit ■ is.

(P) Repeating unit consisting essentially of: 1. Polyester amide consisting of IX, X and -Z-3-X (wherein, Ar is the same as above. Y is 0.NI (or NR
SZ means NH or NR, R has 1 carbon number
~4 alkyl group or aryl group)) General formula +0-Ar-0+ ■ Dioxyaryl unit represented by (wherein A is the same as above) This polyesteramide has unit I Approximately 10 to 90 mol%, unit ■ 5 to 45 mol%, unit X 5 to 45 mol%
, and the unit ■ in an amount of about 0 to 40 mol%. In addition, at least some of the hydrogen atoms bonded to the ring are 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 with selected substituents.

Preferred dicarboxyaryl units (2) are, preferred units (X) are, and preferred dioxyaryl units (2) are.

Furthermore, the polymer forming the anisotropic melt phase of the present invention includes:
Also included are polymers in which a portion of one polymer chain is composed of segments of the polymer that forms the above-mentioned anisotropic melt phase, and the remaining part is composed of segments of thermoplastic resin that do not form the anisotropic melt phase.

The above-mentioned liquid crystalline polymer not only has excellent gas barrier properties at room temperature but also has excellent heat resistance, so that its gas barrier properties do not depend on temperature. That is, gas barrier properties and water vapor barrier properties do not deteriorate even when subjected to high temperature conditions, such as retort sterilization. The heat distortion temperature of the liquid crystalline polymer is usually about 80 to 400°C, preferably about 120 to 350°C.

In particular, a liquid crystalline polymer having a heat deformation temperature of 150 to 250° C. is preferable because it has excellent film-forming properties. Note that the oxygen gas permeability and water vapor permeability of the liquid crystalline polymer are usually 1, Oee
/-・25-・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 that forms an anisotropic melt phase used in the present invention includes: (1) other polymers that form an anisotropic melt phase, (2) thermoplastic resins that do not form an anisotropic melt phase, (2) It may contain at least one of a thermosetting resin, (1) a low-molecular organic compound, and (2) an inorganic substance. Note that the polymer forming the anisotropic melt phase and other components in the composition may be thermodynamically compatible.

Examples of the above thermoplastic resin (■) include polyethylene,
Polypropylene, polybutylene, polybutadiene, polyisoprene, polyvinyl acetate, ethylene-vinyl acetate copolymer, ethylene-acrylic ester copolymer, ethylene-methacrylic ester 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,
Included are polyamide, polyacrylonitrile, polyvinyl alcohol, polyvinyl dimonyl, polyetherimide, polyamideimide, polyetheretherimide, polyetheretherketone, polyethersulfone, polysulfone, polyphenylene sulfide, polyphenylene oxide, and the like.

Examples of the thermosetting resin (2) include phenol resins, epoxy resins, melamine resins, urea resins, unsaturated polyester resins, diallyl phthalate resins, and alkyd resins.

Examples of the low-molecular-weight organic compounds mentioned in (1) above include substances normally added to thermoplastic resins and thermosetting resins, such as plasticizers, weather and light stabilizers such as antioxidants and ultraviolet absorbers, and antistatic agents. , flame retardants, colorants such as dyes and pigments, blowing agents, divinyl compounds, crosslinking agents such as peroxides and vulcanizing agents, and low-carbon compounds used as lubricants to improve fluidity and mold release properties. Includes molecular organic compounds.

Furthermore, the above inorganic substances include, for example, substances normally added to thermoplastic resins and thermosetting resins, such as general inorganic fibers such as glass fibers, carbon fibers, metal fibers, ceramic fibers, boron fibers, and asbestos; Powder substances such as calcium, highly dispersed silicic acid, alumina, aluminum hydroxide, talc powder, mica, glass flakes, glass peas, quartz powder, silica sand, various metal powders, carbon black, barium sulfate, calcined gypsum, and silica carbonate. It includes inorganic compounds such as boron nitride and silicon nitride, whiskers, and metal whiskers.

The thickness of the liquid crystalline polymer layer containing the above-mentioned liquid crystalline polymer is not particularly limited, but is usually about 1 to 500 x/l, preferably 5 to 250 x/l, and more preferably about 10 to 150 x/l.

In the multilayer film of the present invention, polyalkylene terephthalate layers are laminated on both sides of the liquid crystalline polymer layer via an adhesive layer.

The polyalkylene terephthalate has 2 carbon atoms.
6 to 6 alkylene groups, or those having a cycloalkylene group or ether group in a part of the alkylene group, especially polyethylene terephthalate, or polyalkylene terephthalate with high heat resistance, such as a part of ethylene glycol, to 1° So-called PET-G substituted with 4-cyclohexane dimetatool, diethylene glycol, etc.
Polybutylene terephthalate is preferred. Note that polyalkylene terephthalate having high heat resistance can be easily coextruded with the liquid crystalline polymer.

Note that a plurality of polyalkylene terephthalate layers of the same type or different types may be laminated. Furthermore, by laminating the liquid crystal polymer layer and the polyalkylene terephthalate layer, gas barrier properties such as oxygen gas barrier properties can be further improved, and the film has excellent heat resistance.

The thickness of the polyalkylene terephthalate layer is not particularly limited, but is usually about 1 to 50 mm.

The adhesive layer is not particularly limited as long as it exhibits adhesiveness to the liquid crystal polymer layer and the polyalkylene terephthalate layer, and may be a general-purpose film adhesive such as polyurethane, butadiene-acrylonitrile copolymer, or urethane resin. Anchor coating agents such as polymers and alkyl titanates may be used, but preferably contain modified polyolefins or polyesters. These modified polyolefins and polyesters exhibit excellent adhesion to the liquid crystal polymer layer and the polyalkylene terephthalate layer.

The modified polyolefin is a polymer into which a functional group is introduced, and examples of the functional group include a hydroxy group, an alkoxy group, an alkoxycarbonyl group, an amino group, and particularly a carboxy group, a glycidyl group, and an alkoxysilane group. A plurality of these functional groups may be combined. Preferred modified polyolefins include, for example, carboxy-modified polyolefins, glycidyl-modified polyolefins,
Alkoxysilane-modified polyolefin, carboxy-modified ethylene-ethyl acrylate copolymer, glycidyl-modified ethylene-ethyl acrylate copolymer, alkoxysilane-modified ethylene-ethyl acrylate copolymer, carboxy-modified ethylene-vinyl acetate copolymer, glycidyl Examples include modified ethylene-vinyl acetate copolymers, alkoxysilane-modified ethylene-vinyl acetate copolymers, and the like.

In addition, carboxy modification, glycidyl modification, and alkoxysilane modification are, for example, unsaturated carboxylic acids such as acrylic acid and maleic anhydride or their acid anhydrides; polymerizable unsaturated compounds having a glycidyl group such as glycidyl acrylate and glycidyl methacrylate; It means modified with a polymerizable unsaturated compound having an alkoxysilane group such as methacryloxypropyltrimethoxysilane.

Moreover, the above-mentioned polyester has a polyhydric carboxylic acid, a polyhydric alcohol, and a hydroxycarboxylic acid as constituent components, and a small amount of a monohydric carboxylic acid or a -hydric alcohol is used as necessary.

Examples of polyvalent carboxylic acids include divalent or higher carboxylic acids, such as aliphatic acids such as oxalic acid, maleic acid, maleic anhydride, succinic acid, adipic acid, pimelic acid, superric acid, azelaic acid, sebacic acid, and dodecanoic acid. Multivalued carboxylic acid;
Alicyclic polycarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; phthalic acid, phthalic anhydride, terephthalic acid, isophthalic acid, trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride, trimesic acid , naphthalene-2,6-dicarboxylic acid, diphenyl-4,4
Examples include aromatic polyhydric carboxylic acids such as '-dicarboxylic acid and 3-sulfoisophthalic acid. These polyhydric carboxylic acids can be used in combination of one or more types. Among the above polycarboxylic acids, terephthalic acid is preferably the main component, for example, 30 to 80 mol% of the polycarboxylic acid component, and other polycarboxylic acid components are preferably adipic acid, sebacic acid, and isophthalic acid. .

Examples of polyhydric alcohols include dihydric or higher alcohols, such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, trimethylene glycol, and 1,4-butanediol. , 1.3-butanediol, 1.5-bentanediol, 1.6-hexanediol, neopentyl glycol, glycerol, trimethylolpropane, aliphatic polyhydric alcohols such as pentaerythritol; resorcinol, 2.2-bis( 4-hydroxyphenyl)propane, 4.4'-bis(2-hydroxyethyl)phenyl-2,2-propane, 4.4'-bis(2-hydroxypropyl)phenyl-2,2-propane, 4.4 Aromatic polyhydric alcohols such as '-bis(2-hydroxyethoxyethyl)phenyl-2,2-propane are exemplified. These polyhydric alcohols can be used in combination of one or more types. Among the above polyhydric alcohols, ethylene glycol, 1,4-butanediol, and especially 1,4-butanediol are preferred.

Examples of the hydroxycarboxylic acids include aliphatic hydroxycarboxylic acids such as glycolic acid and oxypropionic acid; aromatic hydroxycarboxylic acids such as hydroxybenzoic acid; one or more of them can be used as a mixture.

Note that the term "polyester" as used herein also includes other polymers whose segment constituent components are the constituent components of the polyester, such as polyester ether, polyester amide, polyester carbonate, and the like.

These modified polyolefins and polyesters may be used alone or in combination of two or more. Further, the adhesive layer contains at least 50% by weight, preferably 75% by weight or more of the above-mentioned modified polyolefin and/or polyester.

Further, at least one adhesive layer between each layer may be formed, and multiple layers may be formed as necessary.

The thickness of the adhesive layer is not particularly limited as long as it does not impair adhesiveness, but generally, a thickness of about 0.1 to 50% can ensure sufficient adhesiveness.

Further, the polyalkylene terephthalate layer and the adhesive layer may contain the above-mentioned thermoplastic resin, (2) a low-molecular organic compound, tackifier, wax, etc., and (2) an inorganic substance.

The multilayer film of the present invention can be produced not only by conventional methods such as dry lamination and extrusion lamination, but also by a multilayer molding method in which liquid crystalline polymer is coextruded with polyalkylene terephthalate due to its high melting point, or by a combination of these methods. It can be formed by As the coextrusion multilayer molding method, either a multi-manifold method in which multiple layers are merged in a die or a feed block method can be adopted. Note that during lamination, surface treatment such as corona discharge treatment, sputtering treatment, high frequency treatment, flame treatment, chromic acid treatment, solvent etching treatment, undercoat treatment, etc., or a combination thereof may be performed.

Furthermore, the multilayer film of the present invention may be uniaxially or biaxially stretched to an appropriate ratio by a stretching means such as roll stretching, belt stretching, tenter stretching, or tube stretching.

Note that it is sufficient that at least one of the liquid crystalline polymer layer and the polyalkylene terephthalate layer is 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 packaged items. For example, since it has excellent oxygen gas barrier properties and water vapor barrier properties, it can be used as a packaging material for oil-based cooking materials, in addition to conventional food packaging films, etc.
It can be used as packaging materials for medicines, packaging materials for cosmetics, aroma-retaining packaging materials for aromatic substances, etc. Also under high temperature, e.g.
It is resistant to temperatures as low as 0''C and has no polyolefin odor, so it is particularly suitable for fields that require gas barrier properties at high temperatures, such as packaging materials for foods such as retort foods and microwave foods.

[Effects of the Invention] As described above, according to the multilayer film of the present invention, polyalkylene terephthalate layers are laminated on both sides of the liquid crystalline polymer layer containing a thermotropic liquid crystalline polymer via an adhesive layer. It has excellent heat resistance, no polyolefin odor even when exposed to high temperature and high humidity, and excellent gas barrier properties.

[Examples] The present invention will be described in more detail below based on Examples.

Example 1 Polybutylene terephthalate (PBT) (made of polyplastic ■, in orthochlorophenol, temperature 25°C
Intrinsic viscosity measured at 1. OdJ/g), glycidyl-modified ethylene-vinyl acetate copolymer (a> (manufactured by Sumitomo Chemical Co., Ltd., trade name: Bond First 7B), the repeating unit 1
．． Liquid crystalline polymer (b)'' (manufactured by Polyplastic ■, trade name: Vectra A900) consisting of polyester (^) composed of II was supplied to a feed block type multilayer molding device, and coextruded into five layers. , (P13T
) /(a) /(b)/(a)/(PBT)=25/
A multilayer film of 10/30/10/25- was produced.

Example 2 Polybutylene terephthalate (PBT) of Example 1, maleic anhydride-modified ethylene-ethyl acrylate copolymer (C) of Example 1 (manufactured by Sumitomo Chemical Co., Ltd., trade name Bondine TX8030), glycidyl-modified polyethylene ( d)
(Manufactured by Nippon Oil ■, trade name Rexval J-3,700)
, using the liquid crystalline polymer (b) of Example 1, Example 1
Co-extruded into 7 layers in the same manner as (PBT) / (e)
/ (d) / (b) / (d) / (e)/
(P13T)-20/10/10/30/10/10/
A multilayer film with 20 voices was produced.

Example 3 Polybutylene terephthalate (PBT) of Example 1,
Alkoxysilane-modified ethylene-ethyl acrylate copolymer (e) (manufactured by DuPont Mitsui, trade name HPRAS25
2) Using the liquid crystalline polymer (1)) of Example 1, coextrusion molding was carried out into 5 layers in the same manner as in Example 1, and (PBT>
/ (a) / (b) / (e) / (PBT)
-25/10/30/10/25 multilayer films were produced.

Example 4 In place of polybutylene terephthalate in Example 1, polyethylene terephthalate (PET-G
) (manufactured by Eastman Chemical Products Co., trade name PET-G6763) was coextruded into 5 layers in the same manner as in Example 1 to form (PET-0) / (a) /
(b) /(a))/(PET-G) -25/10/
A multilayer film of 30/10/25- was produced.

Example 5 Example 1 was prepared by using the maleic anhydride-modified ethylene-ethyl acrylate copolymer (C) of Example 1, the glycidyl-modified polyethylene (d) of Example 2, and the liquid crystalline polymer (b) of Example 1. Co-extrusion molded into 5 layers in the same manner as (e)
/ (d) / (b) / (d) / (c) −
A multilayer film of 10/10/30/10/10/ffi was produced.

Then 1. Expanded polyethylene terephthalate (PET) treated with corona discharge with a film thickness of 12 capes (manufactured by Toyobo ■,
(trade name E5100) was thermally laminated to the adhesive layer (e) on both sides of the multilayer film, and (PET)
/(C) /(D) /(B) /(D> /(C)
/(PET)=12/10/10/30/10/10/
A multilayer film of 12 dust particles was prepared.

Comparative Example 1 Polypropylene (PP) (manufactured by Sumima Kagaku Kogyo ■, trade name Noblen Fl, 6315G), maleic anhydride-modified polypropylene (f') (manufactured by Mitsubishi Yuka ■, Models P)
31OK), saponified ethylene-vinyl acetate copolymer (
g) (manufactured by Solvay, trade name Clarene L6),
Coextrusion molding was carried out to form 5 layers in the same manner as in Example 1, and (PP)/
(f') / (g> / (f) / (pp)-
A multilayer film of 25/1 O/30/1 O/25 μι was produced.

Comparative Example 2 Polypropylene (PP) of Comparative Example 1, ethylene-vinyl acetate copolymer (EVA) (Mitsui DuPont ■, trade name Evaflex P1905), polyvinylidene chloride copolymer (vinylidene chloride content 90% by weight) A resin composition consisting of 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, per 100 parts by weight of methyl acrylate content (10% by weight or less). Example 1
In the same manner as above, 5 layers were coextruded to form (PP)/(EV
A) / (PVDC) / (EVA) / (PP)-25
/10/30/10/25 μm multilayer film was produced.

Then, the following test methods were used to determine odor, fragrance retention,
The oxygen gas permeability, water vapor permeability, and oxygen gas permeability after retort sterilization were investigated.

The four odor-prone sides were impulse-sealed, water was poured into a bag with a vent for steam release, and the bag was heated in a microwave oven for 5 minutes, and the presence or absence of a polyolefin odor was evaluated by a sensory test based on the following criteria.

0: No polyolefin odor ×: Polyolefin odor present In order to prevent leakage from the fragrance-retentive sealing part, impulse seals were used on each of the four sides to seal two places at a predetermined interval with a seal width of 15 mm. A 1100MX100 bag containing 5 ml was prepared, and the temperature was 40°C.
The weight loss rate was measured after being left in an environment with relative humidity of 90% for 30 days.

Under the conditions of oxygen gas permeability temperature of 23℃ and relative humidity of 60%, nitrogen gas 98%
%, using a carrier gas consisting of 2% hydrogen gas, AST
It was measured by the method according to MD-3985-81.

Water vapor transmission rate was measured using an infrared sensor according to ASTM F-37273, using air as a carrier gas, under conditions of a temperature of 25° C. and a relative humidity of 90%.

After retort sterilization treatment, immerse in pressurized hot water with an oxygen gas permeability temperature of 120°C for 30 minutes, and then
The measurement was performed under the conditions of a temperature of 20° C. and a relative humidity of 40% according to the method for measuring oxygen gas permeability described above.

The results are shown in the table.

(Hereinafter, blank space) As is clear from the table, compared to the films of Comparative Examples, the films of each Example had no polyolefin odor even when heated, and the weight of methyl salicylate decreased by 0.1% by weight. It had excellent aroma retention properties, as well as oxygen gas barrier properties and moisture proof properties. It was also found that the gas barrier properties of the film of Comparative Example 1 were significantly reduced by heating and humidification treatment, whereas the gas barrier properties of the films of each Example were hardly reduced.

Claims (1)

[Scope of Claims] 1. A multilayer film characterized in that polyalkylene terephthalate layers are laminated on both sides of a liquid crystalline polymer layer containing a thermotropic liquid crystalline polymer via an adhesive layer. 2. The multilayer film according to claim 1, wherein the adhesive layer contains modified polyolefin or polyester.