JP2002248721A - Laminated film and packaging body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated film of which the strength is hard to reduce even when an air-containing retort treatment is applied, which is excellent in heat-sealing property, of which the sealing strength is high, and which is suitable as a packaging material for food or the like being air-containing retort treatment is applied, and a packaging body comprising the laminated film. SOLUTION: For this laminated film, a polyamide resin (X) layer, an adhesive resin (Y) layer, and a thermoplastic resin (Z) layer are respectively laminated in this order. In such a laminated film, for the (X) layer, the relative viscosity is 3.0 to 6.0, a difference (C) between a terminal amino group amount (B) and a terminal carboxyl group amount (A) is 10 or lower, and the water extracting amount is 2 wt.% or lower. The (Z) layer is one of which the melting point is 100 to 170 deg.C. Then, the ratio in the thickness of the laminated film is 90 to 10% for the (X) layer, 1 to 50% for the (Y) layer, and 10 to 90% for the (Z) layer. Also, this packaging body comprises the laminated film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a laminated film and a package. More specifically, the present invention relates to a laminated film composed of a laminated film having a polyamide resin as a main constituent layer and suitable for producing a retort package, and a package composed of the laminated film.

[0002]

2. Description of the Related Art Polyamide resins are excellent in strength, flexibility, transparency, heat resistance, chemical resistance, gas barrier properties, etc., so that molded products and films are used for food packaging materials, medical packaging materials and the like. Widely used for packaging and containers. In packaging materials used for food applications, for example, such as retort pouch, after storing and packaging the food, for the purpose of sterilizing botulinum and the like, a mixture of steam and air in a temperature range of 110 to 145 ° C. (Hereinafter, this sterilization treatment is referred to as “aerated retort treatment”, and the container used at this time is referred to as a “retort container”). A conventionally known film made of a polyamide resin has problems such as a decrease in strength and impact resistance of the packaging material after the above-described aerated retort treatment, and a leakage of contents due to the formation of pinholes.

[0003] Various attempts have been made to improve the quality of a film made of such a polyamide resin after an aerated retort treatment. For example, Patent No. 300
No. 8445 discloses a method of modifying a terminal carboxyl group of a polyamide resin with an aliphatic monoamine, but the effect of preventing a reduction in strength of a packaging material after an aerated retort treatment was insufficient. Also, JP-A-7-138472, JP-A-7-268209, and Patent No. 29174
No. 01 and the like disclose a method of adding an antioxidant to a polyamide resin in order to prevent a reduction in the strength of the packaging material after the aerated retort treatment. The prevention effect could not be said to be sufficient yet.

[0004]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention has been completed as a result of intensive studies to provide a laminated film suitable for manufacturing a retort container and a package comprising the laminated film. Things. The object of the present invention is that (1) the strength is hardly deteriorated even with an aerated retort treatment,
An object of the present invention is to provide a laminated film having excellent heat sealing properties and high sealing strength, which is suitable as a packaging material for foods to be subjected to an aerated retort treatment, and (2) a package made of the laminated film.

[0005]

According to a first aspect of the present invention, a polyamide resin (X) layer, an adhesive resin (Y) layer, and a thermoplastic resin (Z) layer are laminated in this order. The polyamide resin (X) has a relative viscosity in the range of 3.0 to 6.0, the number of terminal carboxyl groups is (A) (μeq / g of resin), and the number of terminal amino groups is Is (B) (μeq / g of resin), the difference in the amount of terminal groups (C) {(B) − (A)} is 1
A thermoplastic resin (Z) comprising a polyamide resin having a water extraction amount of not less than 0 and an amount of water extraction of not more than 2% by weight.
Is composed of a thermoplastic resin having a melting point in the range of 100 ° C. to 170 ° C., and the ratio of the thickness of the laminated film is
The present invention provides a laminated film comprising (X) layer 90 to 10%, (Y) layer 1 to 50%, and (Z) layer 10 to 90%.

According to a second aspect of the present invention, there is provided a package comprising a laminated film in which a polyamide resin (X) layer, an adhesive resin (Y) layer, and a thermoplastic resin (Z) layer are laminated in this order. X) has a relative viscosity of 3.0 to 3.0.
6.0, and the number of terminal carboxyl groups is (A)
(Μeq / g of resin), and the number of terminal amino groups is (B)
(Μeq / g of resin), the difference in the amount of terminal groups (C)
{(B)-(A)} is 10 or more, and the amount of water extraction is 2% by weight or less. The thermoplastic resin (Z) has a melting point of 100 ° C to 170 ° C. Provided is a package made of a laminated film, wherein the package is made of a thermoplastic resin in a range and has a thermoplastic resin (Z) layer as an innermost layer.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The polyamide resin (X) in the present invention functions to improve the gas barrier properties of the laminated film. The polyamide resin (X) is obtained by a polycondensation or copolymerization reaction of a lactam having three or more rings, a polymerizable ω-amino acid, or a dibasic acid and a diamine. 3
Specific examples of lactams having at least a member ring include ε-caprolactam, enantholactam, caprylactam, lauryl lactam, α-pyrrolidone, α-piperidone, and the like. As ω-amino acids, specifically,
6-aminocaproic acid, 7-aminoheptanoic acid, 9-aminononanoic acid, 11-aminoundecanoic acid and the like.

Specific examples of the dibasic acids include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid,
Suberic acid, azelaic acid, sebacic acid, undecandioic acid, dodecadionic acid, tridecadionic acid, tetradecadionic acid, hexadecadionic acid, hexadecenedionic acid, octadecadionic acid, octadescedionic acid, eicosandioic acid, encocene Examples thereof include aliphatic dicarboxylic acids such as diacid, docosandioic acid, and 2,2,4-trimethyladipic acid, and aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, and xylylenedicarboxylic acid.

Specific examples of the diamines include ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, undecamethylenediamine, and dodecamethylene. Diamine, 2,2,4- (or 2,4,4) -trimethylhexamethylenediamine, cyclohexanediamine, bis- (4,4′-aminocyclohexyl) methane, meta-xylylenediamine and the like can be mentioned.

[0010] Polyamide resin (A) is preferably poly-ε-caprolactam (polyamide 6), ε-caprolactam.
And copolymers of caprolactam, adipic acid and hexamethylenediamine (polyamide 6/66 copolymer), and mixtures thereof.

In Japanese Patent No. 3008445, it is effective to reduce the amount of terminal carboxyl groups in order to minimize the decrease in strength after the pneumatic retort treatment, and it is effective to reduce both the amount of terminal amino groups and the amount of terminal carboxyl groups. It is stated that even a small amount is effective. However, according to experiments performed by the present inventors, it was found that when both the amount of terminal amino groups and the amount of terminal carboxyl groups were small, the strength of the film after the aerated retort treatment was greatly reduced. It was found that only when the amount is larger than the predetermined amount, the strength reduction after retorting was small, and the larger the difference in the terminal group amount, the better.

According to experiments by the present inventors, in order to effectively achieve the object of the present invention, the number of terminal carboxyl groups is (A) (μeq / g of resin) and the number of terminal amino groups is ( B) (μeq / g of resin), it was found that the difference (C) in the amount of terminal groups (C) = (B) − (A)} needs to be 10 or more. If the difference (C) in the amount of terminal groups is less than 10, the decrease in film strength after the pneumatic retort treatment is undesirably large. The difference (C) in the amount of terminal groups is more preferably 15 or more, and most preferably 20 or more.

In order to increase the difference in the amount of terminal groups in this way, when a polyamide resin is modified with diamines in the production thereof, the amount of terminal carboxyl groups can be reduced with a relatively small amount of diamines, and at the same time, the amount of terminal amino acids can be reduced. The amount of base can be increased. When the polyamide resin is modified with monoamines, the amount of terminal carboxyl groups can be reduced, but the amount of terminal amino groups does not increase, so it is necessary to increase the amount of monoamines added. It is not preferable because it lowers. In order to increase the difference in the amount of terminal groups as in the present invention, it is industrially preferable to use a diamine for modification.

The difference in the amount of terminal groups of the polyamide resin (X) is
In order to satisfy the requirements of the present invention, when a lactam or ω-amino acid having three or more rings is used as a raw material, a polycondensation reaction is carried out in the coexistence of diamines to convert the dibasic acid and the diamine. When used as a raw material, a polycondensation reaction may be carried out with an excess amount of diamines. As the diamine for modification, in any of the above cases, the same diamine as in the above-mentioned raw material for producing a polyamide resin can be used, and among them, hexamethylene diamine is preferable.

The polyamide resin (X) can be produced by a conventionally known method employing reduced pressure conditions at the end of the reaction. The modifying diamine can be added at any stage before the polycondensation reaction under reduced pressure is started. The pressure at the end of the polycondensation reaction is usually 70 KPa or less, preferably 50 KPa or less. The time for the reduced pressure reaction is usually about 1 to 4 hours.

The terminal group content of the polyamide resin (X) can be measured by a conventionally known method, for example, as described in “Polymer Analysis Handbook” (edited by the Japan Society for Analytical Chemistry). . That is, the terminal amino group is prepared by dissolving the polyamide resin in
It can be measured by titration with N hydrochloric acid, and the terminal carboxyl group can be measured by dissolving the polyamide resin in benzyl alcohol and titrating with 0.01 N caustic soda. When measuring the terminal group content of the polyamide resin layer in the laminated film, only the polyamide resin layer is eluted using an appropriate solvent, and the eluted sample may be quantified by the above method.

The relative viscosity of the polyamide resin (X) is determined by JI
It means a value measured at 98% sulfuric acid concentration of 1% and temperature of 25 ° C. in accordance with SK6810, and it needs to be 3.0 to 6.0. When the relative viscosity is less than 3.0, the melt viscosity is small, so that it becomes difficult to produce a film (film formation).
On the other hand, when the relative viscosity exceeds 6.0, the melt fluidity is insufficient, which is not preferable. The relative viscosity of the polyamide resin is
More preferably, it is 3.0 to 5.5. In order to measure the relative viscosity of the polyamide resin layer in the laminated film, only the polyamide resin layer is eluted using an appropriate solvent, and the eluted sample may be quantified by the above method.

In order to effectively achieve the object of the present invention, the amount of the polyamide resin (X) extracted with water must be 2% or less. If the amount of water extraction exceeds 2%, the amount of gas generated at the time of film production becomes large, and a die line or fish eye tends to appear, which is not preferable in film production. The amount of water extraction is more preferably 1.5% or less. The amount of water extraction was determined by measuring 10 g of a sample in 250 ml of demineralized water.
The extract was boiled under reflux for an hour, and the extract was cooled, diluted 4 times with demineralized water, and then subjected to a TOC meter (TOC-50, manufactured by Shimadzu Corporation).
0 type), the carbon concentration C (% by weight) in the diluent is measured. From the carbon concentration C, it can be calculated by the following equation: water extraction amount = C × 4 × (113/72) × 250/10.

By blending the polyamide resin (X) with an antioxidant, the decrease in the strength of the film after the air-containing retort treatment can be reduced. Copper salts, amine-based, hindered phenol-based, phosphorus-based, and sulfur-based antioxidants can be used as the antioxidant, but hindered phenol-based antioxidants are preferred in view of use in food applications. .

The hindered phenolic antioxidants include N, N'-hexamethylenebis (3,5-di-t-
Butyl-4-hydroxy-hydrocinnamamide) or pentaerythrityl-tetrakis- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], and mixtures thereof.

The addition amount of the antioxidant is preferably 0.001 to 1 part by weight based on 100 parts by weight of the polyamide resin (X). If the amount is less than 0.001 part by weight, the effect of reducing the strength of the film after the pneumatic retort treatment is not reduced. If the amount is more than 1 part by weight, the amount of bleed out to the film surface after the film is produced. Increases,
It is not preferable because the printability is lowered and the film is easily peeled when formed into a laminated film. The amount of antioxidant added is 0.01
-0.5 parts by weight is more preferable, and 0.01-0.25 parts by weight is most preferable.

The polyamide resin (X) has an average particle size of 10
When the polyamide resin layer is the outermost layer, the film can have improved slipperiness. If the average particle size of the filler exceeds 10 μm, the light scattering effect of the filler itself becomes large, and the transparency of the film is undesirably reduced. In the case of a stretched film, the average particle size is more preferably 0.5 to 5 μm, and in the case of an unstretched film, the average particle size is more preferably 1 to 10 μm. The average particle size of the filler can be easily measured by a measuring method using a Coulter counter method or a laser diffraction method, or by observation with an electron microscope.

The amount of the filler having an average particle size of 10 μm or less is 0.001 to 100 parts by weight of the polyamide resin.
1.0 parts by weight is preferred. If the amount is less than 0.001 part by weight, the effect of the addition is not obtained. If the amount is more than 1 part by weight, the transparency of the film is lowered, and both are not preferred. The addition amount of the filler is more preferably 0.01 to 0.6 parts by weight.
The refractive index of the filler having an average particle size of 10 μm or less is preferably similar to that of a polyamide resin from the viewpoint of transparency. The refractive index of the filler is preferably 1.3 to 1.
8, more preferably from 1.4 to 1.7.

Examples of the filler having an average particle diameter of 10 μm or less include inorganic compounds, organic compounds and mixtures thereof. As inorganic compounds, zeolite, talc,
Various naturals such as kaolin, bentonite, montmorillonite, calcium carbonate, zinc carbonate, wollastonite, silica, alumina, magnesium oxide, calcium silicate, sodium aluminate, sodium aluminosilicate, magnesium silicate, glass balloon, zinc oxide, hydrotalcite Minerals and synthetics. Preferred are kaolin, talc, zeolite, silica and the like, among which zeolite and silica are most preferred. Examples of the organic compound include various polymer particles, fine powder, and pulverized product, and preferably, cross-linked polymethyl methacrylate (cross-linked PMMA).

When forming a stretched film, the filler having an average particle diameter of 10 μm or less is preferably subjected to a surface treatment with a silane coupling agent. Unless the surface treatment is performed, the boundary surface between the polyamide resin (X) and the filler surface is peeled off when stretch-molded, voids are generated at the boundary surface, and the transparency of the film may be reduced.

Specific examples of the silane coupling agent include trimethylmethoxysilane, vinyltriethoxysilane, γ-chloropropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N- (β-aminoethyl) -γ -Aminopropyltrimethoxysilane and the like, and vinyltriethoxysilane, γ-aminopropyltriethoxysilane and the like. The amount of the silane coupling agent to be added is generally 1 to 99 parts by weight, preferably 5 to 70 parts by weight, more preferably 10 to 40 parts by weight based on 100 parts by weight of the filler.

Bisamide compounds can be added to the composition of the polyamide resin (X) for the purpose of improving the slipperiness of the film surface. Specific examples of the bisamide compounds include N, N'-methylenebisstearylamide and N, N'-ethylenebisstearylamide. The amount of the bisamide compound to be added is preferably 0.01 to 1 with respect to 100 parts by weight of the polyamide resin.
Parts by weight, and particularly preferably 0.01 to 0.3 parts by weight.

In the composition of the polyamide resin (X), a lubricant, a release agent, a heat deterioration inhibitor, an ultraviolet absorber, an antistatic agent, an antiblocking agent, a dye, and the like may be used as long as they do not impair the object of the present invention. And various resin additives such as pigments, flame retardants, and spreading agents.

As a method of blending an antioxidant, a filler having an average particle diameter of 10 μm or less, a bisamide compound, and other additives into the polyamide resin (X), the polyamide resin (X) may be added in the course of polycondensation of the polyamide resin, or may be added after the polycondensation. Conventionally known methods such as dry blending with a polyamide resin, melt-kneading with a polyamide resin, preparing a high-concentration masterbatch, diluting this at the time of molding and blending it with the polyamide resin, and the like. .

To prepare a package from the laminated film according to the present invention, the innermost layer of the package has a melting point of 100 ° C. to 170 ° C.
The layer made of the thermoplastic resin (Z) in the range (1) is disposed. The thermoplastic resin (Z) layer functions to improve the strength of the laminated film and to improve the heat sealing property when preparing a package from the laminated film. If the melting point of the thermoplastic resin (Z) is less than 100 ° C., it is not preferable because it is melted during the air-containing retort treatment, and if it exceeds 170 ° C., the heat seal strength is insufficient, which is not preferable in the production of a package. The melting point can be measured by a DSC method or the like.

Specific examples of the thermoplastic resin (Z) having a melting point of 170 ° C. or lower preferably include polypropylene, polyethylene, and polypropylene copolymer. Examples of the polypropylene copolymer include a copolymer of propylene with ethylene and / or 1-butene. These thermoplastic resins (Z) may be one kind or a mixture of two or more kinds.

The adhesive resin layer (Y) constituting the laminated film according to the present invention functions so as to firmly bond the boundary between the polyamide resin (X) layer and the thermoplastic resin (Z) layer. As the adhesive resin layer (Y), a modified polyolefin resin is preferable. The modified polyolefin resin is α, β
-Refers to polyolefin resins modified with unsaturated carboxylic acids. Specifically, ethylene, a copolymer of an olefin having propylene as a main component, an α, β-unsaturated carboxylic acid or a derivative thereof (a), and an olefin having ethylene and propylene as a main component. A graft polymer (b) obtained by grafting an α, β-unsaturated carboxylic acid or a derivative thereof to the polymer is exemplified.

As the α, β-unsaturated carboxylic acid or its derivative in the copolymer (a), for example, acrylic acid, methacrylic acid, methyl methacrylic acid, sodium acrylate, zinc acrylate, vinyl acetate, glycidyl methacrylate And the like. Specific examples of the copolymer (a), for example, ethylene-vinyl acetate copolymer,
Examples include ethylene-acrylic acid copolymer, ethylene-ethyl acrylic acid copolymer, ethylene-sodium acrylate copolymer, and the like. Α in the above copolymer (a),
The proportion of β-unsaturated carboxylic acid or its derivative is preferably at most 40 mol%.

Examples of the olefin polymers which are the basis of the graft polymer (b) include, for example, polyethylene, polypropylene, ethylene-propylene copolymer and ethylene-propylene.
Butene-1 copolymer, ethylene-vinyl acetate copolymer,
Examples include an ethylene-acrylic acid copolymer, an ethylene-ethyl acrylic acid copolymer, and an ethylene-sodium acrylate copolymer.

The α, β-unsaturated carboxylic acids or derivatives thereof grafted to the above-mentioned olefin polymers include acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, fumaric acid, acid anhydrides of these, And esters such as tetrahydrofurfuryl alcohol. Preferred among the components to be grafted is maleic anhydride. The graft amount of the olefin polymer to the polymer is preferably 0.05% of the olefin polymer.
~ 1.5% by weight.

The grafting of an α, β-unsaturated carboxylic acid or a derivative thereof to a polymer of olefins is carried out by mixing both components according to a conventional method and melting the mixture at a resin temperature of 150 to 300 ° C. In the graft polymerization, when an organic peroxide such as α, α'-bis-t-butylperoxy-p-diisopropylbenzene is blended in an amount of 0.001 to 0.05% by weight based on the olefin polymer, the efficiency is improved. Good graft polymerization can be achieved.

The above-mentioned modified polyolefin resin may be mixed with an unmodified polyolefin resin in the range of 0 to 90% by weight. 90 unmodified polyolefin resin
If the content is more than 10% by weight, the adhesiveness is undesirably reduced.
To the modified polyolefin resin, various conventionally used resin additives such as pigments, dyes, heat stabilizers, and antistatic agents can be further compounded within a range not to impair the object of the present invention.

The laminated film according to the present invention includes, for example,
(1) Co-extrusion sheet molding, co-extrusion T-die molding, co-extrusion air-cooled inflation molding, so-called co-extrusion method such as co-extrusion water-cooled inflation molding, (2) After producing a stretched or unstretched single-layer film, by lamination method It can be produced by a method of laminating it with another film, (3) a method of stretching a laminated film and producing a laminated stretched film, or the like. As a stretching method for a single-layer film or a laminated film, a conventionally known stretching method can be used, and specifically, a tubular or tenter simultaneous biaxial stretching method, a tenter type horizontal stretching after a roll type longitudinal stretching, and the like. A sequential biaxial stretching method for stretching is exemplified.

The thickness of the laminated film according to the present invention is 3 to
It is selected in the range of 300 μm. If the thickness of the laminated film is too large, the transparency is reduced, and if it is too small, the pinhole resistance is apt to be reduced, and both are not preferred. The thickness ratio of each layer constituting the laminated film is determined by the polyamide resin (X) layer 9
The ratio is 0 to 10%, the adhesive resin (Y) layer is 1 to 50%, and the (Z) thermoplastic resin (Z) layer is 10 to 90%. If the ratio is out of this range, the strength of the film after the air-containing retort treatment is significantly deteriorated, or the heat sealability is poor, which is not preferable. The laminated film according to the present invention may be subjected to a corona discharge treatment on one or both sides for the purpose of improving printability and laminability.

The laminated film according to the present invention includes three layers of a polyamide resin (X) layer, an adhesive resin (Y) layer, and a thermoplastic resin (Z) layer. Aluminum foil can also be laminated. Other thermoplastic resin films include polyamide resins other than polyamide resin (X), semi-aromatic polyamide resins, ethylene vinyl alcohol copolymer, polyvinylidene chloride, polyethylene, polypropylene, ethylene vinyl acetate copolymer, polyester Resins.
When laminating a film or an aluminum foil made of another thermoplastic resin, the form between the (X) layer and the (Y) layer is
It can be arranged between the (Y) layer and the (Z) layer, or can be arranged on the surface of the (X) layer. At this time, it is preferable that the (Y) layer is interposed between the layers.

The laminated film according to the present invention preferably has a strength retention of 60% or more after the laminated film is subjected to an aerated retort treatment at 130 ° C. for 30 minutes. When the strength retention is 60% or more, it means that the strength is hardly reduced even by the air-containing retort treatment, and the object of the present invention can be achieved. On the other hand, if the strength retention is less than 60%, it means that the strength is likely to be reduced by the air-containing retort treatment, and the object of the present invention cannot be achieved.

The package according to the second aspect of the present invention can be manufactured using the laminated film according to the first aspect. The method for manufacturing the package according to the second invention is not particularly limited, and is excellent in heat sealability (Z).
A layer or another film layer made of a thermoplastic resin may be opposed as the innermost layer and heat-sealed. The form of the heat seal is such that the innermost layer of the laminated film is folded or the two sheets are overlapped, and the outer peripheral edge is further sealed, for example, a side seal type, a two-side seal type, a three-side seal type, Examples of the sealing method include a four-sided seal type, an envelope-attached seal type, a gasket-attached seal type (pillow seal type), a foldable seal type, a flat bottom seal type, and a square bottom seal type. A tube container can be manufactured using the laminated film according to the first invention.

The heat sealing method is not particularly limited, and includes a bar sealing method, a rotating roll sealing method,
Conventionally known methods such as a belt sealing method, an impulse sealing method, a high frequency sealing method, and an ultrasonic sealing method can be used. The package obtained by the sealing method may be provided with a spout of one-piece type or two-piece type, a zipper for opening and closing, and the like.

The laminated film according to the first invention of the present invention comprises:
It can be used for manufacturing the package according to the second invention of the present invention.
The package according to the second aspect of the present invention is preferably used as a container for storing various foods that are subjected to an aerated retort process after storing articles, and as a container for storing medical supplies that are sterilized at a high temperature before storing the articles. used. The shape of the package is not particularly limited.

[0045]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof. In addition, the raw materials used in the following Examples and Comparative Examples are as follows.

(1) PA1 to PA8 (polyamide resin) In a 200-liter autoclave equipped with a stirrer, a thermometer, a reflux condenser, a jacket, etc., 60 kg of caprolactam and a 5% aqueous solution of disodium hydrogen phosphite 0.1% were added. One liter and the amounts of the amines and carboxylic acids shown in Table 1 were charged as shown in Table 1. After these were purged with nitrogen, the mixture was heated through a heating medium in a jacket while stirring at 16 rpm while the autoclave was sealed to carry out a condensation reaction. Internal temperature 270 ° C,
When the gauge pressure reaches 0.8 MPa, the pressure is released to atmospheric pressure,
Next, the pressure was gradually reduced until the final pressure shown in Table 1 was reached.

After reaching the predetermined pressure, the reaction was further performed for 3 hours. Thereafter, the stirring was stopped, nitrogen was introduced, the pressure was returned to normal pressure, and the obtained polyamide was taken out of the autoclave in the form of a strand, cut out with a rotary cutter, and pelletized. The operation of introducing the obtained pellets into 150 liters of boiling pure water to extract unreacted monomers was repeated five times. After completion of the extraction operation,
By drying at kPa until the water content became 0.1% or less, eight types of polyamide resins (PA1 to PA8) were obtained. In addition,
PA4 was dried without performing extraction operation with boiling pure water.

[0048]

[Table 1]

Eight types of polyamide resins (PA1 to PA)
8) The amount of terminal amino groups, the amount of terminal carboxyl groups, the relative viscosity, the amount of water extraction, etc. were quantified by the method described above. The results are shown in Table-2. The melting point of the polyamide resin PA1 was 221 ° C.

[0050]

[Table 2]

(2) AO1: N, N'-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamide) (manufactured by Ciba-Geigy, antioxidant, trade name: Irganox) 1098). (3) AO2: pentaerythrityl-tetrakis- @ 3-
(3,5-di-t-butyl-4-hydroxyphenyl)
Propionate (Ciba Geigy, antioxidant, trade name: Irganox 1010).

(4) F1: Silica having an average particle size of 1.5 μm and a refractive index of 1.46 (trade name: Sylysia 310, manufactured by Fuji Silysia Chemical Ltd.). (5) F2: zeolite having an average particle size of 5.5 μm and a refractive index of 1.5 (manufactured by Mizusawa Chemical Industries, trade name: Shilton AMT5)
0). (6) F3: crosslinked P having an average particle size of 6.0 μm and a refractive index of 1.5
MMA (Nippon Shokubai Co., Ltd., product name: Eposter MA100
6).

(7) AD1: polyolefin adhesive resin (trade name: Modic AP, manufactured by Mitsubishi Chemical Corporation, grade name: P513V). (8) PO1: polypropylene copolymer having a melting point of 170 ° C. or lower (manufactured by Nippon Polychem, grade name: EG7C).

The evaluation test of the laminated film and the package is as follows.
The procedure was as described below. (a) Film-forming property: From a (X) layer (140 μm thickness), a (Y) layer (10 μm thickness) and a (Z) layer (30 μm thickness) by a three-layer inflation film forming machine (Placo). The resulting three-layer film was manufactured into a laminated film having a thickness of 180 μm by a water-cooled inflation method. Those in which these were not recognized were evaluated as ○, and those in which they were recognized were evaluated as ×, and displayed.

(B) Breaking strength: For a laminated film of a sample, at a temperature of 23 ° C. and a humidity of 65% RH, a film not subjected to the aerated retorting was adjusted for 1 day, and a film after the aerated retorting was adjusted for 4 days or more. After the dampening, Tensilelon manufactured by Orientec Co., Ltd. was used to evaluate the tensile strength at break according to JIS K7127. The strength retention (%) is expressed by the following equation:
It was calculated according to (rupture strength of film after air retort treatment) / (rupture strength of film without air retort treatment) × 100. The strength retention rate is preferably 60% or more and the numerical value is larger. If it is lower than this, the packaging bag tends to be damaged after the pneumatic retort treatment.

The air-containing retort treatment method for the laminated film was as follows. The laminated film is
An autoclave for pneumatic retort treatment of retort foods (manufactured by Tommy Seiko Co., Ltd.) was cut into test pieces having a size of 280 mm in the D direction × 160 mm in the TD direction and fixed to a stainless steel jig.
(Model: SR-240 type), first raise the temperature to 100 ° C while discharging the air in the autoclave, then close the exhaust valve, continue to raise and raise the temperature, and when the internal temperature reaches 130 ° C, And maintained for 30 minutes at an internal pressure of 0.31 MPa. Thereafter, the internal pressure was increased to 0.34 MPa, and cooling water was poured into the autoclave to cool the internal temperature to 70 ° C. The film after cooling was removed from the above jig, the moisture was wiped off, the humidity was controlled at a temperature of 23 ° C. and a relative humidity of 65%, and the tensile strength at break was measured.

(C) Heat sealing property: The laminated film is MD
It is cut into a test piece having a size of 400 mm in the direction x 160 mm in the TD direction, and is bent in the MD direction almost at the center of the long side so that the inner layer is on the inner side to have a half length. Heat sealed, 200mm
A package of × 160 mm was manufactured. At this time, those which could be heat-sealed were indicated by ○, and those which could not be heat-sealed were indicated by ×.

(D) Drop test after retort treatment: 200 g of colored water in the package produced in the above heat sealability test
, And the other end was heat-sealed while evacuating the package to prepare a package in which water was sealed. The obtained package containing water is placed in the above-mentioned autoclave for aerated retorting, and subjected to aerated retorting at a temperature of 130 ° C. for 30 minutes in the same procedure as above, and then the package containing water. Was dropped onto the floor from a height of 50 cm, and the contents were visually observed for leakage. The case where no leakage was observed from the package in which the water was sealed was indicated by 、, and the case where leakage was observed or the bag was broken was indicated by ×.

[Examples 1 to 6 and Comparative Examples 1 to 5] PA1 to PA8 {Polyamide resin (X)}
, An antioxidant of the type and amount shown in Table 2 was blended with a filler, and AD1 {adhesive resin (Y)},
PO1 {Thermoplastic resin (Z)} is made from three kinds of resins by a three-layer inflation film forming machine (Placo).
(X) layer (thickness 140 μm), (Y) layer (thickness 10 μm)
A three-layer film consisting of layers m) and (Z) (thickness 30 μm) and having a total thickness of 180 μm was produced by a water-cooled inflation method. During the production of the laminated film, the film forming property was evaluated. Thereafter, the laminated film was simultaneously biaxially stretched with a biaxial stretching machine (manufactured by TM Long) at a temperature of 80 ° C. to a stretching ratio of 3 × 3 times, and heat-set at a temperature of 210 ° C. A 20 μm laminated stretch film made of a polyamide resin was produced. The breaking strength of the obtained laminated stretched film was measured. Table 3 shows the measurement results.
It was shown to.

[0060]

[Table 3]

From Tables 1 to 3, the following becomes clear. (1) The laminated film according to the embodiment of the present invention has a difference in the terminal group amount of the polyamide resin (X) (C) ｛the terminal amino group amount (B) −
Since the amount of terminal carboxyl groups (A)｝, the relative viscosity, the amount of water extraction, etc. are in the ranges specified in claim 1, the strength retention after the aerated retort treatment is higher than 60%, and the aerated retort treatment The strength does not decrease significantly even if
To Example 6). (2) In the case where an antioxidant is blended with the polyamide resin (X), the decrease in strength after the air-containing retort treatment is small as compared with the case where this is not blended (Examples 1 and 5,
See Example 3 and Example 5). (3) On the other hand, the laminated film of the comparative example in which the difference (C) in the terminal group amount of the polyamide resin (X) is less than 10 has a strength retention after the aerated retort treatment of lower than 60%, The strength is significantly reduced by the retort treatment (see Comparative Examples 1 to 4). (4) Furthermore, in the case of Comparative Example 5 using PA4 having a water extraction amount of 2% by weight or more, a large amount of gas is generated during film formation, a large number of die lines and fish eyes are generated in the film, and the appearance is poor. No measurement of breaking strength was performed.

[Examples 7 to 13 and Comparative Examples 6 to
Comparative Example 7] In the above PA {polyamide resin (X)},
The type and amount of the antioxidant shown in No. 3 were mixed with fillers, respectively, and AD1 {adhesive resin (Y)}, PO1
(X) layer (thickness: 40 μm), (Y) layer (thickness: 3 μm) and (Z) by using a three-layer inflation film forming machine (manufactured by Placo). ) The total thickness of the layers (7 μm thick) is 50 μm
Was produced by a water-cooled inflation method. About the obtained laminated film, the breaking strength was measured, and the measurement result was shown in Table-4.

[0063]

[Table 4]

From Tables 1, 2, and 4, the following becomes clear. (1) The laminated film according to the embodiment of the present invention has a difference in the terminal group amount of the polyamide resin (X) (C) ｛the terminal amino group amount (B) −
Since the amount of terminal carboxyl groups (A)｝, the relative viscosity, the amount of water extraction, etc. are in the ranges specified in claim 1, the strength retention after the aerated retort treatment is higher than 60%, and the aerated retort treatment Does not significantly reduce the strength (Example 7
To Example 13). (2) When the antioxidant is blended with the polyamide resin (X), the decrease in strength after the air-containing retort treatment is small compared to the case where the antioxidant is not blended (Examples 9 and 1).
0, see Example 7 and Example 11). (3) On the other hand, the laminated film of the comparative example in which the difference (C) in the terminal group amount of the polyamide resin (X) is less than 10 has a strength retention after the aerated retort treatment of lower than 60%, The strength is significantly reduced by the retort treatment (see Comparative Examples 6 to 7).

[Examples 14 to 15 and Comparative Example 8]
Comparative Example 9] The above-mentioned PA {polyamide resin (X)} was mixed with an antioxidant of the type and amount shown in Table 4 and a filler, respectively, and AD1 {adhesive resin (Y)}, thermoplastic resin The three types of resin (Z) were applied to a (X) layer (with a thickness of 40 μm) by a three-layer inflation film forming machine (manufactured by Placo).
m), (Y) layer (thickness 3 μm) and (Z) layer (thickness 7
A three-layer film having a thickness of 50 μm was manufactured from the three-layer film having a thickness of 50 μm by a water-cooled inflation method.
About the obtained laminated film, the breaking strength was measured, and the measurement result was shown in Table-5.

[0066]

[Table 5]

From Tables 1, 2 and 5, the following becomes clear. (1) The laminated film of the example of the present invention, in which the innermost layer is made of a polyolefin-based resin, has excellent heat sealing properties, strong sealing strength, and breaks even after a drop test of the package after retort treatment. (See Examples 14 to 15). (2) On the other hand, even if the innermost layer is made of a polyolefin-based resin, the package of Comparative Example 8 in which the difference (C) in the terminal group amount of the polyamide resin (X) is less than 10 has a heat seal property. Is excellent, but the package is broken in a drop test after retort treatment, and the sealing strength is weak. Comparative Example 9 in which the innermost layer was a polyamide resin was inferior in heat sealability and could not be processed into a package.

[0068]

As described in detail above, the present invention has the following particularly advantageous effects, and its industrial value is extremely large. 1. In the laminated film according to the present invention, the difference in the amount of terminal groups of the polyamide resin (X) (C) ｛the amount of terminal amino groups (B) −
Since the amount of terminal carboxyl groups (A)｝, relative viscosity, water extraction amount, etc. are in specific ranges, the strength retention rate after aerated retorting is higher than 60%, and the strength is maintained even after aerated retorting. Does not drop significantly. Therefore, it is suitable for the production of packages of various foods to be retorted. 2. In the laminated film according to the present invention, since the water extraction amount of the polyamide resin (X) is in a specific range, the amount of gas generated at the time of film production is small, die lines and fish eyes are hardly generated, and the appearance of the film is reduced. Are better. 3. When an antioxidant is added to the polyamide resin (X), the laminated film according to the present invention preferably has an improved strength retention after the aerated retort treatment. 4. The laminated film according to the present invention has a strength retention rate of 60% or more after being subjected to the aerated retort treatment at 130 ° C. for 30 minutes. It is suitable for storing various foods to be retorted. 5. The package prepared from the laminated film according to the present invention is excellent in heat sealability and seal strength because the innermost layer is made of a polyolefin resin.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 77/00 C08L 77/00 (72) Inventor Seiji Morimoto 5-6-1 Higashi-Hachiman, Hiratsuka-shi, Kanagawa Prefecture Inside the Technology Center of Mitsubishi Engineering-Plastics Co., Ltd. (72) Michio Nakata 5-6-2, Higashi-Hachiman, Hiratsuka-shi, Kanagawa Prefecture F-term in the Technology Center of Mitsubishi Engineering-Plastics Co., Ltd. 3E086 AB01 AD01 BA04 BA15 BB41 BB51 BB85 CA01 4F100 AA20 AC04 AH02A AH02H AH03A AH03H AK01B AK03G AK04B AK07B AK07J AK25 AK46A AK48A AK48J AL01A AL01B AL06A BA02 CA06A CA23 CB00 EH20 GB15 GB23 JA04B JA06A JA20A JA20B JB16B JK01 JK10 JL12 YY00 YY00A YY00B 4J002 CL031 EJ036 FD076 GF00 GG02

Claims (8)

[Claims] 1. A laminated film in which a polyamide resin (X) layer, an adhesive resin (Y) layer and a thermoplastic resin (Z) layer are laminated in this order, the polyamide resin (X) having a relative viscosity of 3 When the number of terminal carboxyl groups is (A) (μeq / g of resin) and the number of terminal amino groups is (B) (μeq / g of resin), the amount of terminal groups is in the range of 0.0 to 6.0. (C) {(B)-(A)} is 1
A thermoplastic resin (Z) comprising a polyamide resin having a water extraction amount of not less than 0 and an amount of water extraction of not more than 2% by weight.
Is composed of a thermoplastic resin having a melting point in the range of 100 ° C. to 170 ° C., and the ratio of the thickness of the laminated film is
A laminated film comprising (X) layer 90 to 10%, (Y) layer 1 to 50%, and (Z) layer 10 to 90%. 2. The polyamide resin (X) layer contains 0.00% of an antioxidant per 100 parts by weight of the polyamide resin (X).
The laminated film according to claim 1, wherein the laminated film is blended in an amount of 1 to 1 part by weight. 3. The laminated film according to claim 2, wherein the antioxidant is a hindered phenolic antioxidant. 4. An antioxidant comprising (N, N′-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydroxy)
Hydrocinnamamide)) and / or pentaerythrityl-tetrakis- {3- (3,5-di-t-butyl-
The laminated film according to claim 2, which is (4-hydroxyphenyl) propionate}. 5. The polyamide resin according to claim 1, wherein the polyamide resin is polyamide 6 and / or a polyamide 6/66 copolymer.
The laminated film according to any one of claims 4 to 4. 6. The laminated film according to claim 1, wherein the thermoplastic resin (Z) layer is made of any of polypropylene, polyethylene, a polypropylene copolymer, or a mixture thereof. 7. The laminated film is heated at 130 ° C. for 30 minutes.
The laminated film according to any one of claims 1 to 6, wherein a strength retention rate after an air-containing retort treatment is 60% or more. 8. In a package made of a laminated film in which a polyamide resin (X) layer, an adhesive resin (Y) layer, and a thermoplastic resin (Z) layer are laminated in this order, the polyamide resin (X) When the viscosity is in the range of 3.0 to 6.0 and the number of terminal carboxyl groups is (A) (μeq / g of resin) and the number of terminal amino groups is (B) (μeq / g of resin), The difference in base amount (C) {(B)-(A)} is 1
A thermoplastic resin (Z) comprising a polyamide resin having a water extraction amount of not less than 0 and an amount of water extraction of not more than 2% by weight.
Is a package made of a laminated film, wherein the package is made of a thermoplastic resin having a melting point in the range of 100 ° C. to 170 ° C. and has a thermoplastic resin (Z) layer as an innermost layer.